WO2024075621A1 - Stacked iron core and manufacturing method of stacked iron core - Google Patents

Stacked iron core and manufacturing method of stacked iron core Download PDF

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Publication number
WO2024075621A1
WO2024075621A1 PCT/JP2023/035358 JP2023035358W WO2024075621A1 WO 2024075621 A1 WO2024075621 A1 WO 2024075621A1 JP 2023035358 W JP2023035358 W JP 2023035358W WO 2024075621 A1 WO2024075621 A1 WO 2024075621A1
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block
end faces
steel plate
steel
surface roughness
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PCT/JP2023/035358
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French (fr)
Japanese (ja)
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崇人 水村
尚 茂木
克 高橋
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日本製鉄株式会社
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Publication of WO2024075621A1 publication Critical patent/WO2024075621A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H01F27/245—Magnetic cores made from sheets, e.g. grain-oriented
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/33—Arrangements for noise damping

Definitions

  • the present invention relates to a stacked core and a method for manufacturing a stacked core.
  • Patent Document 1 discloses partially interposing vibration-damping steel sheets between a plurality of laminated electromagnetic steel sheets.
  • Patent Literature 2 discloses that after forming grooves on the sheet surface of each electromagnetic steel sheet, multiple electromagnetic steel sheets are stacked so that the sheet surfaces not formed with the grooves do not overlap each other.
  • Patent Literature 2 also discloses that an adhesive resin is applied to the end surfaces of the multiple stacked electromagnetic steel sheets.
  • Patent Document 3 discloses providing a stress member that is compressively deformed along the longitudinal direction of a plane that constitutes the outer periphery of an iron core.
  • Patent Document 4 discloses stacking a plurality of electrical steel sheets, each having an insulating coating containing 4.9 to 7.1% Si and having a surface roughness Rmax of 3.5 ⁇ m or more, and also discloses inserting an impregnating agent, which also functions as an adhesive, between the stacked electrical steel sheets.
  • Patent Documents 1 to 4 require a material other than the steel sheet to suppress vibration of the stacked core.
  • the present invention has been made in consideration of the above problems, and has an object to provide a stacked core that can suppress vibration without using a material other than steel sheets.
  • the stacked core of the present invention comprises a plurality of blocks, each having a plurality of stacked steel plates, the plurality of blocks having block opposing end faces, the block opposing end faces being end faces among the end faces of the blocks that are positioned opposite each other of the blocks, and each of at least one pair of the block opposing end faces satisfies the following formula (A), and the pair of block opposing end faces are two of the block opposing end faces that are arranged in positions opposite each other. 1 ⁇ Ra(D)/Ra(S) ⁇ 12 ...
  • Ra(D) is the surface roughness Ra ( ⁇ m) of the block-facing end face in the stacking direction of the steel plate
  • Ra(S) is the surface roughness Ra ( ⁇ m) of the plate surface of the steel plate having an end face that constitutes part of the block-facing end face, in the direction of the main magnetic flux flowing through the steel plate or the rolling direction of the steel plate.
  • the method for manufacturing a stacked core of the present invention is a method for manufacturing a stacked core having a plurality of blocks each having a plurality of stacked steel plates, and includes a cutting process for cutting the steel plate, a first roughness measurement process for measuring the surface roughness Ra(S) ( ⁇ m) of the plate surface of the steel plate cut in the cutting process, a second roughness measurement process for measuring the surface roughness Ra(D) ( ⁇ m) of the block-facing end surface of the block having the steel plate to be measured for the surface roughness Ra(S), and a roughness adjustment process for adjusting the surface roughness of the block-facing end surface when the ratio Ra(D)/Ra(S) of the surface roughness Ra(D) measured in the second roughness measurement process to the Ra(S) measured in the first roughness measurement process does not satisfy 1 ⁇ Ra(D)/Ra(S) ⁇ 12,
  • the roughness Ra(S) is the surface roughness Ra( ⁇ m) in the direction of the main magnetic flux flowing through the steel plate when
  • FIG. 1 is a diagram showing an example of a stacked core.
  • FIG. 2A is a diagram illustrating a first example of measurement positions for the surface roughness in the lamination direction.
  • FIG. 2B is a diagram illustrating a second example of the measurement positions for the surface roughness in the lamination direction.
  • FIG. 2C is a diagram illustrating a third example of the measurement positions of the surface roughness in the lamination direction.
  • FIG. 2D is a diagram illustrating a fourth example of the measurement positions of the surface roughness in the lamination direction.
  • FIG. 2E is a diagram illustrating a fifth example of the measurement positions of the surface roughness in the stacking direction.
  • FIG. 3A is a diagram illustrating a first example of measurement positions for in-plane surface roughness.
  • FIG. 3A is a diagram illustrating a first example of measurement positions for in-plane surface roughness.
  • FIG. 3A is a diagram illustrating a first example of measurement positions for in-plane surface roughness
  • FIG. 3B is a diagram illustrating a second example of the measurement positions for the in-plane surface roughness.
  • FIG. 3C is a diagram illustrating a third example of the measurement positions of the in-plane surface roughness.
  • FIG. 3D is a diagram illustrating a fourth example of the measurement positions for the in-plane surface roughness.
  • FIG. 3E is a diagram illustrating a fifth example of the measurement positions for the in-plane surface roughness.
  • FIG. 4A is a diagram illustrating a first example of the number of crystal grains on the opposing end surface of a steel sheet and the length of the opposing end surface of a steel sheet.
  • FIG. 4B is a diagram illustrating a second example of the number of crystal grains on the opposing end surface of the steel sheet and the length of the opposing end surface of the steel sheet.
  • FIG. 4C is a diagram illustrating a third example of the number of crystal grains on the opposing end surface of the steel sheet and the length of the opposing end surface of the steel sheet.
  • FIG. 4D is a diagram illustrating a fourth example of the number of crystal grains on the opposing end surface of the steel sheet and the length of the opposing end surface of the steel sheet.
  • FIG. 4E is a diagram illustrating a fifth example of the number of crystal grains on the opposing end surface of the steel sheet and the length of the opposing end surface of the steel sheet. 4 is a flowchart showing an example of a method for manufacturing a stacked core.
  • compared objects including length, position, size, spacing, etc., being the same includes not only objects that are strictly the same, but also objects that are different within the scope of the invention (for example, objects that differ within the tolerance range determined at the time of design).
  • FIG. 1 is a diagram showing an example of a stacked core 100. Note that the x-y-z coordinates shown in FIG. 1 are shown for convenience in explaining the orientation of each part.
  • the stacked core 100 shown in FIG. 1 is, for example, a stacked core (a so-called three-phase stacked core) around which a coil through which a three-phase AC current flows is wound. Note that the current flowing through the coil wound around the stacked core 100 is not limited to three-phase AC. For example, the current flowing through the coil wound around the stacked core 100 may be a single-phase AC current.
  • the stacked core 100 is also used as an iron core provided in various devices.
  • the stacked core 100 may be, for example, an iron core provided in a transformer, a current transformer, a rotating electric machine, and a reactor.
  • stacked core 100 comprises multiple blocks 110a to 110e.
  • Each of blocks 110a to 110e has multiple steel plates stacked together with their plate surfaces facing each other.
  • the double-arrowed lines shown within multiple blocks 110a-110e indicate the direction of the main magnetic flux flowing through the steel sheet when the blocks 110a-110e are excited, or the rolling direction.
  • the direction of the main magnetic flux flowing through the steel sheet when the blocks 110a-110e are excited will be referred to as the main magnetic flux direction as necessary.
  • the main magnetic flux direction is determined by excluding the main magnetic flux flowing in each block in areas where the direction changes due to flow in and out of other blocks (i.e., the main magnetic flux direction is the direction in which the main magnetic flux travels straight). If the steel sheet is a grain-oriented electromagnetic steel sheet, it is preferable that the main magnetic flux direction and the rolling direction are as close as possible, and it is more preferable that they coincide. Also, if the steel sheet is a grain-oriented electromagnetic steel sheet, it is preferable that the rolling direction and the easy magnetization direction (direction parallel to the easy magnetization axis) are as close as possible, and it is more preferable that they coincide.
  • the main magnetic flux direction can be either the main magnetic flux direction or the rolling direction.
  • the steel plates are not stacked so that the direction of the double-headed arrows shown in the multiple blocks 110a to 110e is approximately parallel (preferably parallel) to the rolling direction of the steel plates, this means that the main magnetic flux direction (or rolling direction) is the main magnetic flux direction.
  • the rolling direction can be determined by observing the surface of the steel plates, so it is easy to determine the rolling direction.
  • the stacked core 100 is configured to have a two-fold symmetric relationship with its center line CL as the axis of rotational symmetry.
  • the center line CL is an imaginary straight line that passes through the position of the center of gravity of the stacked core 100 and extends in the stacking direction (z-axis direction) of the steel plates that make up the stacked core 100.
  • the stacking direction of the steel plates that make up the stacked core 100 will be abbreviated to the stacking direction as necessary.
  • a case where a plurality of blocks 110a to 110e are configured by stacking a plurality of grain-oriented electromagnetic steel sheets having the same steel type and sheet thickness is illustrated.
  • the steel sheets are not limited to grain-oriented electromagnetic steel sheets.
  • the steel sheets may be, for example, bi-directional electromagnetic steel sheets.
  • the steel sheets may be non-oriented electromagnetic steel sheets. At least one of the steel types and sheet thicknesses of the steel sheets configuring at least two of the plurality of blocks may be different. At least one of the steel types and sheet thicknesses of the plurality of steel sheets configuring one block may be different.
  • the thicknesses (lengths in the stacking direction (z-axis direction)) of the plurality of blocks 110a to 110e are the same is illustrated.
  • a case where the blocks 110a to 110b are configured and arranged to have a two-fold symmetric relationship with the center line CL as the axis of rotational symmetry is illustrated.
  • a case where the blocks 110c to 110d are configured and arranged to have a two-fold symmetric relationship with the center line CL as the axis of rotational symmetry is illustrated.
  • the number, shape, size, and arrangement of the blocks are determined according to the specifications of the device that includes the stacked core, and therefore are not limited to those illustrated in FIG.
  • the end faces of the multiple blocks 110a to 110e include block-facing end faces 111a to 111p.
  • the block-facing end faces 111a to 111p of the blocks 110a to 110e are the end faces of the blocks 110a to 110e that are positioned opposite each other.
  • the end faces of the block 110a include block-facing end faces 111a to 111d.
  • the end faces of the block 110b include block-facing end faces 111e to 111h.
  • the end faces of the block 110c include block-facing end faces 111i to 111j.
  • the end faces of the block 110d include block-facing end faces 111k to 111l.
  • the end faces of the block 110e include block-facing end faces 111o to 111p.
  • block opposing end faces arranged in a mutually opposing position are referred to as a pair of block opposing end faces.
  • block opposing end face 111a of block 110a and block opposing end face 111i of block 110c are arranged in a mutually opposing position. Therefore, these block opposing end faces 111a and 111i are a pair of block opposing end faces 111a and 111i.
  • the stacked core 100 illustrated in FIG. 1 has eight pairs of block opposing end faces: 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
  • a pair of block opposing end faces (for example, block opposing end faces 111a and 111i) is a so-called butt portion. Therefore, some or all of the areas of a pair of opposing end faces of blocks (two opposing end faces of blocks) are in contact with each other.
  • block opposing end faces 111a to 111p are separated by bending points that appear when linear approximations of lines representing block opposing end faces 111a to 111p that can be seen when stacked core 100 is viewed from the stacking direction (z-axis direction) are made (see block opposing end faces 111c and 111d, 111g and 111h, 111m and 111n, and 111o and 111p shown in FIG. 1).
  • the block opposing end faces 111a to 111p that can be seen when viewing the stacked core 100 from the stacking direction (z-axis direction) can be more accurately approximated by curve approximation (for example, approximation with a quadratic function) rather than linear approximation
  • the block opposing end faces may be divided at the positions that show the extreme values of the curve approximation.
  • the stacked core 100 of this embodiment will be described along with the findings of the inventors.
  • the findings of the inventors will be described using the symbols shown in FIG. 1.
  • the findings of the inventors are not limited to the stacked core 100 shown in FIG. 1.
  • Vibrations at the butt joints of blocks 110a to 110e have a large impact on the noise of stacked core 100.
  • the inventors focused on the shape of the steel plates in order to suppress such vibrations at the butt joints of blocks 110a to 110e without using a material other than the steel plates.
  • the inventors then discovered that by optimizing the roughness of block opposing end faces 111a to 111p, it is possible to suppress the noise of stacked core 100 by suppressing vibrations at the butt joints of blocks 110a to 110e (block opposing end faces 111a to 111p).
  • vibration of the block butt joints can be suppressed by satisfying the following formula (1) in at least one pair of block opposing end faces (two block opposing end faces) among multiple pairs of block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
  • Ra(D) is the surface roughness Ra ( ⁇ m) in the lamination direction (z-axis direction) of one of the pair of block opposing end faces (two block opposing end faces) to be calculated using formula (1).
  • the surface roughness determined for each block opposing end face in this manner is referred to as lamination direction surface roughness as necessary.
  • Ra(S) is the surface roughness Ra ( ⁇ m) in the main magnetic flux direction (or the rolling direction of the steel plate) of the plate surface having an end face that constitutes a part of the block opposing end face.
  • the surface roughness determined in this manner is referred to as in-plane direction surface roughness as necessary.
  • the surface roughness Ra (lamination direction surface roughness Ra(D) and in-plane direction surface roughness Ra(S)) is the average height Rc of the roughness curve element defined in JIS B 0601:2013.
  • the block opposing end face is composed of the end faces of multiple stacked steel plates.
  • the end face constituting a part of the block facing end face is the end face of one of the multiple steel plates.
  • the ( ⁇ m) in Ra( ⁇ m) indicates that the unit of surface roughness Ra is micrometers (this method of expressing units is the same for the other variables n, L, and n/L).
  • the in-plane surface roughness Ra(S) is, for example, 0.10 ⁇ m or more and 3.00 ⁇ m or less.
  • the pair of block opposing end faces (two block opposing end faces) for which formula (1) is calculated are the pair of block opposing end faces 111a and 111i.
  • formula (1) is satisfied for each of block opposing end faces 111a and 111i, then formula (1) is satisfied for each of one pair of block opposing end faces 111a and 111i.
  • Whether formula (1) is satisfied is similarly determined for the other pairs of block opposing end faces 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
  • FIGS. 2A to 2E are diagrams for explaining an example of the measurement position of the surface roughness Ra(D) in the lamination direction.
  • the y-z coordinates shown in Fig. 2A and Fig. 2D correspond to the y and z coordinates of the x-y-z coordinate system shown in Fig. 1.
  • the x-z coordinates shown in Fig. 2B, Fig. 2C, and Fig. 2E correspond to the x and z coordinates of the x-y-z coordinate system shown in Fig. 1.
  • block 110a shown in Fig. 2A and block 110b shown in Fig. 2D are configured and arranged to have a two-fold symmetric relationship with the center line CL of stacked core 100 as the axis of rotational symmetry.
  • block 110c shown in Fig. 2B and block 110d shown in Fig. 2D are configured and arranged to have a two-fold symmetric relationship with the center line CL of stacked core 100 as the axis of rotational symmetry
  • FIGS. 2A and 2D are diagrams showing an example of measurement positions for the stacking direction surface roughness Ra(D) of block facing end faces 111a-111d, 111e-111h of blocks 110a, 110b.
  • FIGS. 2B and 2E are diagrams showing an example of measurement positions for the stacking direction surface roughness Ra(D) of block facing end faces 111i-111j, 111k-111l of blocks 110c, 110d.
  • FIG. 2C is a diagram showing an example of measurement positions for the stacking direction surface roughness Ra(D) of block facing end faces 111m-111p of block 110e.
  • the surface roughness in the lamination direction, Ra(D), is measured on an imaginary straight line passing through the center positions of both ends of the opposing block end faces of the pair of opposing block end faces to be calculated using formula (1) when the opposing block end faces are viewed from the lamination direction of the steel plate having an end face that constitutes part of the opposing block end faces.
  • the stacking direction of the steel plates having end faces that form part of the block opposing end faces 111a to 111p is the z-axis direction.
  • the positions of the centers of both ends 113a and 113b, 113c and 113d, 113e and 113f, 113f and 113g, 113h and 113i, 113j and 113k, 113e and 113f, 113f and 113g, 113l and 113m, and 113m and 113n are positions 112a, 112b, 112c, 112d, 112e, 112f, 112g, and 112h, respectively.
  • the center positions of both ends of the opposing block end faces are obtained in the stacking direction (z-axis direction).
  • virtual straight lines 201a to 201p are obtained as shown in Figures 2A to 2E.
  • the stacking direction surface roughness Ra(D) of block opposing end faces 111a and 111i is measured on imaginary straight lines 201a and 201e, respectively, as shown in Figures 2A and 2B.
  • the roughness curves for calculating the stacking direction surface roughness Ra(D) of block opposing end faces 111b and 111l are measured on imaginary straight lines 201b and 201p, respectively, as shown in Figures 2A and 2E.
  • the roughness curves for calculating the stacking direction surface roughness Ra(D) of the block opposing end faces 111c and 111m are measured on the virtual straight lines 201c and 201g, respectively.
  • the roughness curves for calculating the stacking direction surface roughness Ra(D) of the block opposing end faces 111d and 111n are measured on the virtual straight lines 201d and 201h, respectively.
  • lamination direction measurement positions are the positions of the bevel cut surfaces as shown in FIGS. 2A to 2E.
  • the multiple steel plates constituting one of the pair of block opposing end faces to be calculated using formula (1) are extracted one by one, and the stacking direction surface roughness Ra (D) of the extracted steel plate is measured at the stacking direction measurement position.
  • the stacking direction surface roughness Ra (D) of the steel plate before stacking used to construct the block having the one block opposing end face may be measured at the stacking direction measurement position.
  • Such measurements are performed for all steel plates constituting the one block opposing end face. For example, if the number of stacked sheets is 200, 200 stacking direction surface roughnesses Ra (D) are measured for one block opposing end face.
  • the representative value of the multiple stacking direction surface roughnesses Ra (D) measured in this manner is taken as the stacking direction surface roughness Ra (D) of the one block opposing end face.
  • the representative value is, for example, the arithmetic mean value. Instead of the arithmetic mean value, a median value or the like may be used.
  • the stacking direction surface roughness Ra(D) of the other block facing end face of the pair of block facing end faces being calculated using formula (1) is calculated in the same manner as the stacking direction surface roughness Ra(D) of one block facing end face.
  • the lamination direction surface roughness Ra(D) of one and the other of a pair of block opposing end faces is calculated in the above manner for each of block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
  • FIGS. 3A to 3E are diagrams illustrating an example of measurement positions of a roughness curve for calculating the in-plane surface roughness Ra(S).
  • the x-y coordinates shown in FIG. 3A to FIG. 3E correspond to the x-coordinate and y-coordinate of the x-y-z coordinate system shown in FIG. 1.
  • Figures 3A and 3D are diagrams showing an example of measurement positions of roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces constituting part of the block-facing end faces 111a-111d, 111e-111h of blocks 110a and 110b.
  • Figures 3B and 3E are diagrams showing an example of measurement positions of roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces constituting part of the block-facing end faces 111i-111j, 111k-111l of blocks 110c and 110d.
  • Figure 3C is a diagram showing an example of measurement positions of roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces constituting part of the block-facing end faces 111m-111p of block 110e.
  • the direction perpendicular to the main magnetic flux direction (or rolling direction) and lamination direction of the steel plate is referred to as the width direction as necessary.
  • the roughness curve for calculating the in-plane surface roughness Ra(S) is measured on a virtual straight line that passes through the center position in the width direction of the steel plate and extends along the main magnetic flux direction (or rolling direction) of the steel plate on the plate surface having end faces that form part of the opposing end faces of the pair of blocks to be calculated using formula (1).
  • the lamination direction of the steel plates having end faces that constitute part of the block-facing end faces 111a to 111p is the z-axis direction.
  • the main magnetic flux direction (or rolling direction) of the steel plates that constitute part of the block-facing end faces 111a to 111d, 111e to 111h is the y-axis direction (the direction of the double-headed arrow in FIG. 1).
  • the width direction of the steel plates that constitute part of the block-facing end faces 111a to 111d, 111e to 111h is the x-axis direction.
  • the main magnetic flux direction (or rolling direction) of the steel plates that constitute part of the block-facing end faces 111i to 111j, 111k to 111l, 111m to 111p is the x-axis direction (the direction of the double-headed arrow in FIG. 1).
  • the width direction of the steel plates that constitute part of the block-facing end faces 111i to 111j, 111k to 111l, 111m to 111p is the y-axis direction.
  • the imaginary line that passes through the center in the width direction (x-axis direction) of a steel plate having end faces that form part of the block-facing end faces 111a to 111d and extends along the main magnetic flux direction (or rolling direction, y-axis direction) of the steel plate is imaginary line 301a.
  • the imaginary line that passes through the center in the width direction (x-axis direction) of a steel plate having end faces that form part of the block-facing end faces 111e to 111h and extends along the main magnetic flux direction (or rolling direction, y-axis direction) of the steel plate is imaginary line 301d.
  • the imaginary line that passes through the center in the width direction (y-axis direction) of a steel plate having an end face that constitutes part of the block-facing end faces 111i to 111j and extends along the main magnetic flux direction (or rolling direction, x-axis direction) of the steel plate is imaginary line 301b.
  • the imaginary line that passes through the center in the width direction (y-axis direction) of a steel plate having an end face that constitutes part of the block-facing end faces 111k to 111l and extends along the main magnetic flux direction (or rolling direction, x-axis direction) of the steel plate is imaginary line 301e.
  • the imaginary line that passes through the center position in the width direction (y-axis direction) of the steel plate having an end face that constitutes part of the block-facing end faces 111m to 111p and extends along the main magnetic flux direction (or rolling direction, x-axis direction) of the steel plate is imaginary line 301c.
  • the roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces that constitute part of the block-facing end faces 111a-111d and 111e-111h are measured on the imaginary straight lines 301a and 301d, respectively.
  • the roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces that constitute part of the block-facing end faces 111i-111j and 111k-111l are measured on the imaginary straight lines 301b and 301e, respectively.
  • the roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces that constitute part of the block-facing end faces 111m-111p are measured on the imaginary straight line 301c.
  • the virtual line may be separated into multiple lines depending on the shape of the steel plate.
  • the roughness curve is measured on any one of the multiple separated virtual lines.
  • the roughness curve may be measured on the multiple virtual lines as if the multiple virtual lines were not separated (i.e., the distance between the multiple virtual lines is set to 0 (zero)).
  • in-plane measurement positions the positions of the virtual straight lines 301a to 301e where the roughness curve (roughness curve elements) for calculating the in-plane surface roughness Ra(S) are measured will be referred to as in-plane measurement positions as necessary.
  • the multiple steel plates constituting one of the pair of block opposing end faces to be calculated using formula (1) are extracted one by one, and the in-plane surface roughness Ra(S) of the extracted steel plate is measured at the in-plane measurement position.
  • the in-plane surface roughness Ra(S) of the steel plate before lamination used to construct the block having the one of the block opposing end faces may be measured at the in-plane measurement position.
  • Such measurements are performed for each of all steel plates constituting the one of the block opposing end faces. For example, if the number of stacked sheets is 200, 200 in-plane surface roughnesses Ra(S) are measured for one of the block opposing end faces.
  • the representative value of the multiple in-plane surface roughnesses Ra(S) measured in this manner is taken as the in-plane surface roughness Ra(S) of the one of the block opposing end faces.
  • the representative value is, for example, the arithmetic mean value. Instead of the arithmetic mean value, a median value or the like may be used.
  • the in-plane surface roughness Ra(S) of the other of the pair of opposing block end faces that are the subject of calculation of equation (1) is calculated in the same manner as the in-plane surface roughness Ra(S) of one of the opposing block end faces.
  • the in-plane surface roughness Ra(S) of one and the other of a pair of opposing block end faces is calculated in the above manner for each of the pairs of opposing block end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
  • a roughness curve (roughness curve element) is measured.
  • the roughness curve (roughness curve element) is measured, for example, for each of the multiple steel plates that make up the opposing end face of one block.
  • the roughness curve (roughness curve element) is measured at each of the stacking direction measurement position and the in-plane direction measurement position.
  • the number of laminated sheets is 200
  • 200 roughness curves (roughness curve elements) are measured for one block-facing end face as a roughness curve (roughness curve element) for calculating the laminate direction surface roughness Ra (D).
  • the representative value of the multiple roughness curves (200 in the above example) measured in the above manner is used as the roughness curve for calculating the laminate direction surface roughness Ra (D) of the one block-facing end face.
  • the representative value of the multiple roughness curves (200 in the above example) is calculated by calculating the representative value of the values at the same position in the plate thickness direction in each of the multiple roughness curves.
  • the representative value is, for example, the arithmetic mean value.
  • a median value or the like may be used.
  • a roughness curve obtained by joining multiple roughness curves (200 in the above example) may be used as the roughness curve (roughness curve element) for calculating the laminate direction surface roughness Ra (D).
  • the roughness curves for calculating the in-plane surface roughness Ra(S) are measured for all steel plates having end faces that constitute a part of one block facing end face, for example. For example, if the number of laminated sheets is 200, 200 roughness curves are measured for one block facing end face as roughness curves for calculating the in-plane surface roughness Ra(S). The representative value of the multiple roughness curves (200 in the above example) measured in this manner is used as the roughness curve for calculating the in-plane surface roughness Ra(S) of the steel plate having an end face that constitutes a part of the block facing end face.
  • the representative value of the multiple roughness curves can be obtained, for example, by calculating the calculated average value of values at the same position (x coordinate and y coordinate) in the plate surface direction.
  • the representative value is, for example, the arithmetic mean value.
  • the median value or the like may be used instead of the arithmetic mean value.
  • the measurement magnification is set to 200 times so that the width of one field of view is 500 ⁇ m ⁇ 500 ⁇ m.
  • the measurement magnification is preferably 100 times or more, and more preferably 500 times to 700 times.
  • Ra(D)/Ra(S) Using the in-plane surface roughness Ra(S) and the stacking direction surface roughness Ra(D) calculated for the same block facing end face, Ra(D)/Ra(S) is calculated, and it is confirmed whether the calculated Ra(D)/Ra(S) satisfies formula (1).
  • the method for satisfying formula (1) may be any method capable of adjusting the roughness of the end surface of the steel sheet.
  • the roughness of the end surface of the steel sheet is adjusted by, for example, any one of grinding, cutting, and polishing.
  • the roughness of the end faces of each steel plate may be adjusted.
  • the roughness of the end faces of each steel plate cut into the planar shapes of the blocks 110a to 110e may be adjusted.
  • the roughness of the end faces of each steel plate may be adjusted by controlling the clearance between the upper and lower blades of the shearing machine.
  • the roughness of the end faces corresponding to the block-facing end faces 111a to 111p may be adjusted. Also, any two or more of these may be combined.
  • the end faces corresponding to the block-facing end faces 111a to 111p satisfy formula (1). If formula (1) is not satisfied, the roughness of the end faces may be readjusted. Also, after disassembling the stacked multiple steel plates, the roughness of the end face of each steel plate may be readjusted. Also, without adjusting the roughness of the end faces of the steel plates before stacking the multiple steel plates, it may be confirmed whether the end faces corresponding to the block-facing end faces 111a to 111p satisfy formula (1) after stacking the multiple steel plates. If formula (1) is not satisfied, the roughness of the end faces may be adjusted so that formula (1) is satisfied.
  • At least one pair of block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p satisfy formula (1) (preferably also formula (2)).
  • the inventors also focused on the crystal grains of the steel plate in order to suppress vibrations at the butt joints (block-facing end faces) of the blocks 110a to 110e without using a material other than the steel plate.
  • the end faces of the steel plate having end faces constituting part of the block-facing end faces 111a to 111p are referred to as the steel plate-facing end faces as necessary.
  • the number of crystal grains present in the steel plate having the steel plate-facing end face that includes the steel plate-facing end face as a boundary is referred to as the number of crystal grains on the steel plate-facing end face as necessary.
  • the value obtained by dividing the number of crystal grains on the steel plate-facing end face by the length of the steel plate-facing end face is referred to as the number of crystal grains per unit length on the steel plate-facing end face as necessary.
  • the number of crystal grains on the steel plate-facing end face is n (pieces).
  • the length of the steel plate-facing end face is L (mm). Then, the number of crystal grains per unit length on the steel plate-facing end face is n/L (pieces/mm).
  • the inventors investigated the relationship between the number of crystal grains per unit length n/L on the steel plate facing end face and the noise level of the stacked core 100.
  • the number of crystal grains per unit length n/L on the steel plate facing end face was calculated as follows. First, the number of crystal grains per unit length n/L on the steel plate facing end face was calculated for all steel plates having an end face constituting a part of one of the pair of block facing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
  • the arithmetic mean value of the number of crystal grains per unit length n/L on the calculated steel plate facing end face was calculated as the number of crystal grains per unit length n/L on the steel plate facing end face at the one of the block facing end faces.
  • the inventors have found that the noise level of the stacked core 100 changes significantly due to the vibration of the butt joints of the blocks 110a to 110e (block facing end faces 111a to 111p) when the number n/L per unit length on the steel plate facing end face is 0.5 (pieces/mm).
  • vibration of the stacked core 100 can be suppressed by satisfying the following formula (3) in at least one of the pair of block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, or 111h and 111p (preferably both of the block opposing end faces).
  • n / L ⁇ 0.5 ...
  • Figures 4A to 4D are diagrams illustrating an example of the number n of crystal grains on the opposing end faces of the steel plate and the length L of the opposing end faces of the steel plate.
  • FIGS. 4A and 4D are diagrams for explaining the number n of crystal grains on the steel plate facing end faces constituting part of the block facing end faces 111a-111d, 111e-111h of blocks 110a and 110b, and the length L of the steel plate facing end faces.
  • FIGS. 4B and 4E are diagrams for explaining the number n of crystal grains on the steel plate facing end faces constituting part of the block facing end faces 111i-111j, 111k-111l of blocks 110c and 110d, and the length L of the steel plate facing end faces.
  • FIG. 4C is a diagram for explaining the number n of crystal grains on the steel plate facing end faces constituting part of the block facing end faces 111m-111p of block 110e, and the length L of the steel plate facing end faces.
  • a crystal grain group 401a consisting of five crystal grains is shown as an example of crystal grains that include the steel plate facing end face as a boundary among the crystal grains present in one of the steel plates having a steel plate facing end face that constitutes part of the block facing end face 111a.
  • the number n of crystal grains on the steel plate facing end face that constitutes part of the block facing end face 111a is 5.
  • the number n of crystal grains on the steel plate facing end faces that constitute part of the block facing end faces 111b to 111p other than the block facing end face 111a is also counted in the same manner.
  • 4A to 4E show crystal grain groups 401b, 401c, 401d, 401e, 401f, 401g, 401h, 401i, 401j, 111m, 111n, 111o, 111p, 111e, 111f, 111g, 111h, 111k, and 111l, which are crystal grain groups that include the steel plate facing end face as a boundary, and are made up of four, three, five, seven, six, five, four, four, three, five, four, three, five, seven, and six crystal grains, respectively, among the crystal grains present in one steel plate among the steel plates having the steel plate facing end face that constitutes a part of the block facing end faces 111b, 111c, 111d, 111i, 111j, 111m, 111
  • the method for counting the number n of crystal grains on the opposing end surface of the steel plate may be any method capable of measuring the number of crystal grains.
  • the number n of crystal grains on the opposing end surface of the steel plate may be counted by observing with an electron microscope or an optical microscope as follows. First, the opposing end surface (cut surface) of the steel plate is corroded with a 5% nital solution for 100 to 300 seconds, and then the grain boundaries are observed with an optical microscope.
  • an optical microscope for example, an industrial microscope BX53M manufactured by Olympus Corporation may be used.
  • the length L of the steel plate facing end face is the length of the steel plate facing end face as seen when the steel plate having the steel plate facing end face is viewed in a direction perpendicular to the plate surface of the steel plate (perpendicular to the paper surface of Figures 4A to 4E).
  • Figure 4A shows that the length L of the steel plate facing end face constituting part of the block facing end face 111a is length L1.
  • the length L of the steel plate facing end faces constituting part of the block facing end faces 111b to 111p other than the block facing end face 111a is measured in the same manner.
  • L2, L3, L4, L5, L6, L7, L8, L9, L10, L11, L12, L13, L14, L15, and L16 are shown as the length L of the steel plate facing end faces constituting part of the block facing end faces 111b, 111c, 111d, 111i, 111j, 111m, 111n, 111o, 111p, 111e, 111f, 111g, 111h, 111k, and 111l, respectively.
  • the method for measuring the length L of the opposing end faces of the steel plate may be any method capable of measuring the length of the end faces of the steel plate.
  • the length L of the opposing end faces of the steel plate may be measured by direct measurement using a vernier caliper or the like.
  • the length L of the opposing end faces of the steel plate may also be measured by indirect measurement using image analysis or the like.
  • the crystal grain size of the steel sheet may be controlled to satisfy formula (3) by controlling at least one of the amount of nitriding during nitriding annealing for controlling precipitates and texture, and the annealing temperature and holding time (relationship between annealing temperature and time) during finish annealing for causing secondary recrystallization.
  • the crystal grain size of the steel sheet may be controlled to satisfy formula (3) by performing at least one of the following: adjusting the flow rate of ammonia supplied to the atmosphere during nitriding annealing, adjusting (lengthening) the soaking time during finish annealing, and providing a holding time before reaching the soaking temperature during finish annealing and adjusting the holding time.
  • FIG. 5 is a flowchart showing an example of a method for manufacturing the stacked core 100 of this embodiment.
  • a steel plate manufacturing process is performed.
  • steel plates constituting the stacked core 100 are manufactured.
  • a known method may be adopted as a method for manufacturing the steel plates.
  • the crystal grain size of the steel plate is controlled so as to satisfy the formula (3).
  • the annealing conditions may be controlled to control the crystal grain size of the steel plate.
  • step S502 a cutting process is performed.
  • the steel plate manufactured in step S501 is cut.
  • the steel plate manufactured in step S501 is cut so that the shape of the plate surface of the steel plate after cutting becomes the planar shape of blocks 110a to 110e (the shape of the x-y plane shown in FIG. 1).
  • a known method may be adopted as a method for cutting the steel plate.
  • the steel plate may be cut by punching.
  • the steel plate may be cut by laser processing.
  • the number of steel plates cut at one time in the cutting process is not limited.
  • the steel plates may be cut one by one. Multiple steel plates may be cut at once.
  • step S503 a grain measurement process is performed.
  • the number of grains n/L per unit length on the steel plate facing end face is calculated (measured), and it is confirmed whether or not formula (3) is satisfied.
  • the number of grains n on the steel plate facing end face of the steel plate cut in step S502 and the length L of the steel plate facing end face are measured.
  • the number of grains n/L per unit length on the steel plate facing end face is calculated.
  • the determination of whether or not formula (3) is satisfied is performed for each of the block facing end faces 111a to 111p.
  • a representative value e.g., the arithmetic mean value
  • a representative value e.g., the arithmetic mean value
  • At least one of the calculation of the number of crystal grains per unit length on the opposing end face of the steel plate n/L and the determination of whether the number of crystal grains per unit length on the opposing end face of the steel plate n/L satisfies formula (3) may be performed by a computer.
  • information including the number of crystal grains n on the opposing end face of the steel plate and the length L of the opposing end face of the steel plate may be input to a computer.
  • at least one of the calculation of the number of crystal grains per unit length on the opposing end face of the steel plate n/L and the determination of whether the number of crystal grains per unit length on the opposing end face of the steel plate n/L satisfies formula (3) may be performed manually.
  • step S501 If the number of crystal grains per unit length on the opposing end faces of the steel plate, n/L, does not satisfy formula (3), for example, step S501 is performed again. In this case, only steel plates that do not satisfy formula (3) are produced in step S501.
  • a first roughness measurement process is performed in step S504.
  • the in-plane surface roughness Ra(S) of the steel plate cut in step S502 is calculated (measured).
  • the roughness curve of the steel plate cut in step S502 is measured at the in-plane measurement position (the position of the virtual straight lines 301a to 301e). Then, based on the roughness curve at the in-plane measurement position, the in-plane surface roughness Ra(S) is calculated.
  • the calculation of the in-plane surface roughness Ra(S) is performed, for example, for all the steel plates constituting the blocks 110a to 110e.
  • the calculation of the in-plane surface roughness Ra(S) may be performed by a computer.
  • the calculation of the in-plane surface roughness Ra(S) may also be performed by a person.
  • step S505 a second roughness measurement process is performed.
  • the lamination direction surface roughness Ra(D) of the block facing end face of the block having the steel plate to be measured for the in-plane direction surface roughness Ra(S) is calculated (measured).
  • all the steel plates constituting a certain block are taken out from the steel plates cut in step S502.
  • the roughness curve of the steel plate constituting the block is measured at the lamination direction measurement position (position on the virtual straight lines 201a to 201p).
  • the lamination direction surface roughness Ra(D) is calculated based on the roughness curve at the lamination direction measurement position.
  • the lamination direction surface roughness Ra(D) is calculated, for example, for all the block facing end faces 111a to 111p of all the blocks 110a to 110e constituting the stacked core 100.
  • the lamination direction surface roughness Ra(D) may be calculated by a computer. Additionally, the calculation of the layer direction surface roughness Ra(D) may be performed manually.
  • step S506 a roughness adjustment process is performed.
  • the roughness adjustment process it is determined whether or not each of the pair of opposing end faces of the blocks satisfies formula (1) (preferably also formula (2)), and the surface roughness of the opposing end faces of the blocks that do not satisfy formula (1) (preferably also formula (2)) is adjusted.
  • the in-plane surface roughness Ra(S) and the stacking direction surface roughness Ra(D) calculated (measured) for a pair of block opposing end faces are used to determine whether or not each of the pair of block opposing end faces satisfies formula (1) (preferably also formula (2)). This determination is made, for example, for all block opposing end faces 111a to 111p of blocks 110a to 110e. This determination may also be made by a computer. This determination may also be made by a person.
  • the roughness of the steel plate facing end faces that do not satisfy formula (1) (and preferably formula (2)) is adjusted.
  • the adjustment of the roughness of the steel plate end faces is performed, for example, on all of the block facing end faces 111a to 111p of blocks 110a to 110e that do not satisfy formula (1) (and preferably formula (2)).
  • At least one pair of block opposing end faces (for example, a pair of block opposing end faces 111a and 111i) is made to satisfy 1 ⁇ Ra(D)/Ra(S) ⁇ 12. Therefore, it is possible to provide a stacked core that can suppress vibration without using a material other than steel plate. Furthermore, if 1 ⁇ Ra(D)/Ra(S) ⁇ 12 is changed to 6 ⁇ Ra(D)/Ra(S) ⁇ 8, the noise suppression effect of the stacked core 100 can be more reliably improved.
  • the number of crystal grains per unit length on the steel plate facing end surface, n/L is set to 0.5 or less on at least one of at least one pair of block facing end surfaces (e.g., block facing end surfaces 111a and 111i). Therefore, vibration of the stacked core can be further suppressed.
  • the present invention is not limited to this embodiment.
  • the various conditions shown in this embodiment are example conditions adopted to confirm the feasibility and effects of the present invention. Therefore, the present invention is not limited to the example conditions shown in this embodiment.
  • various conditions may be adopted in the present invention as long as they do not deviate from the gist of the present invention and achieve the object of the present invention.
  • Grain-oriented electrical steel sheets were produced using slabs of steel types A to E having the chemical compositions shown in Table 1.
  • the units of values shown in Table 1 are mass %.
  • the balance of each slab (chemical components other than those shown in Table 1) is Fe.
  • Grain-oriented electrical steel sheets were manufactured using slabs of steel types A to E using the manufacturing process and conditions shown in Table 2.
  • the hot rolling process, hot-rolled sheet annealing process, cold rolling process, decarburization annealing process, nitriding treatment (nitriding annealing) process, and finish annealing process were carried out in this order under the manufacturing conditions shown in Table 2.
  • the cold-rolled steel sheet after decarburization annealing was subjected to nitriding treatment (nitriding annealing) in a mixed atmosphere of hydrogen, nitrogen, and ammonia.
  • the amount of nitriding was adjusted by adjusting the flow rate of ammonia using ammonia nitriding.
  • an annealing separator containing magnesia or alumina as its main component was applied to the cold-rolled steel sheet, and finish annealing was performed.
  • the annealing separator multiple types of annealing separators with different mixture ratios of components including the main component were used.
  • the annealing temperature during finish annealing and the holding time at the annealing temperature were adjusted.
  • the crystal grain size of the steel sheet after finish annealing was controlled by the amount of nitriding in the nitriding treatment and the annealing temperature and holding time during finish annealing.
  • An insulating coating solution was applied onto the primary coating formed on the surface of the steel sheet after final annealing.
  • a solution containing chromium and whose main components were phosphate and colloidal silica was used as the insulating coating solution.
  • the steel sheet to which the insulating coating solution was applied was heat treated to form an insulating coating.
  • grain-oriented electrical steel sheets were manufactured from slabs of steel types A to E in the manner described above. In the following explanation, the grain-oriented electrical steel sheets manufactured from slabs of steel types A to E will be referred to as steel sheets of steel types A to E as necessary.
  • FIG. 1 A stacked core 100 having the shape shown in FIG. 1 was manufactured using steel plates of steel type A as a material.
  • the inventors have found that there is a directly proportional relationship between Ra(D)/Ra(S) shown in formula (1) and the clearance.
  • the roughness of the end surface of the steel plate of steel type A was adjusted by controlling the clearance between the upper and lower blades of a shearing machine.
  • the steel plates of steel type A having the planar shapes of the blocks 110a to 110e were stacked to manufacture the blocks 110a to 110e.
  • a plurality of sets of blocks 110a to 110e in which the roughness of the block facing end surfaces 111a to 111p differed from each other were manufactured.
  • a plurality of sets of blocks 110a to 110e were manufactured for the steel plates of steel types B to E.
  • blocks manufactured from steel plates of steel types A to E will be referred to as blocks of steel types A to E, as necessary.
  • blocks 110a, 110b, 110c, 110d, and 110e will be referred to as upper block 110a, lower block 110b, left block 110c, center block 110d, and right block 110e, as necessary.
  • the stacked core 100 was manufactured by combining blocks 110a-110e manufactured from steel plates of the same steel type.
  • the stacked core 100 manufactured in this manner will be referred to as stacked core 100 of steel types A-E as necessary.
  • the left block 110c, center block 110d, and right block 110e, and the upper block 110a and lower block 110b were considered as blocks manufactured from steel plates of different steel types, and the stacked core 100 was manufactured by combining blocks 110a-110e.
  • stacked cores 100 of steel types A and B, stacked cores 100 of steel types A and D, stacked cores 100 of steel types B and C, and stacked cores 100 of steel types B and E were manufactured.
  • the stacked core 100 of steel types A and B is a stacked core in which the left block 110c, the center block 110d, and the right block 110e are made of steel type A, and the upper block 110a and the lower block 110b are made of steel type B.
  • the stacked core 100 of steel types A and D is a stacked core in which the left block 110c, the center block 110d, and the right block 110e are made of steel type A, and the upper block 110a and the lower block 110b are made of steel type D.
  • the stacked core 100 of steel types B and C is a stacked core in which the left block 110c, the center block 110d, and the right block 110e are made of steel type B, and the upper block 110a and the lower block 110b are made of steel type C.
  • the stacked core 100 of steel types B and E is a stacked core in which the left block 110c, the center block 110d, and the right block 110e are made of steel type E, and the upper block 110a and the lower block 110b are made of
  • the width (length in the y-axis direction), height (length in the x-axis direction), and thickness (length in the z-axis direction) of the stacked core 100 were 750 mm, 750 mm, and approximately 41 mm, respectively.
  • the widths (lengths in the x-axis direction) of the upper block 110a and the lower block 110b, and the widths (lengths in the y-axis direction) of the left block 110c, the center block 110d, and the right block 110e were 150 mm.
  • the lengths L (L1 to L15) of the steel plate facing end faces of the steel plates of steel types A to E having the planar shapes of the blocks 110a to 110e were measured with a vernier caliper.
  • the steel plate facing end faces (sheared surfaces) of the steel plates were corroded with a 5% nital solution for 100 to 300 seconds.
  • the steel plate facing end faces were then observed with an industrial microscope BX53M manufactured by Olympus Corporation to count the number of crystal grain boundaries present on the steel plate facing end faces.
  • the number of crystal grains n on the steel plate facing end faces was calculated by adding 1 to the counted number.
  • the number of crystal grains n/L per unit length on the steel plate facing end faces was calculated from the length L of the steel plate facing end faces and the number of crystal grains n on the steel plate facing end faces obtained from the same steel plate.
  • the number of crystal grains n/L per unit length on the steel plate facing end faces was calculated individually for all the steel plates constituting the blocks 110a to 110e. Then, the arithmetic mean value of the number n/L of crystal grains per unit length on the steel plate facing end face was calculated for each of the block facing end faces 111a to 111p.
  • the arithmetic mean value of the number n/L of crystal grains per unit length on the steel plate facing end face calculated for one block facing end face was taken as the number n/L of crystal grains per unit length on the steel plate facing end face for that block facing end face.
  • the lamination direction surface roughness Ra(D) and in-plane direction surface roughness Ra(S) were calculated in accordance with JIS B 0601:2013.
  • each block facing end face 111a-111p of each stacked core 100 the multiple steel plates constituting that block facing end face were extracted one by one, and the stacking direction surface roughness Ra(D) of the extracted steel plate was measured at the stacking direction measurement position (position on the imaginary line 201a-201p) using a one-shot 3D shape measuring instrument (model name: VR-6000) manufactured by Keyence Corporation.
  • the arithmetic average value of the stacking direction surface roughness Ra(D) of that block facing end face calculated from the multiple steel plates constituting the same block facing end face was calculated as the stacking direction surface roughness Ra(D) of that block facing end face.
  • each block facing end face 111a-111p of each stacked core 100 the multiple steel plates constituting that block facing end face were extracted one by one, and the in-plane surface roughness Ra(S) of the extracted steel plate was measured at the in-plane measurement positions (positions on the imaginary lines 301a-301e) using a one-shot 3D shape measuring instrument (model name: VR-6000) manufactured by Keyence Corporation.
  • the arithmetic average value of the in-plane surface roughness Ra(S) of that block facing end face calculated from the multiple steel plates constituting the same block facing end face was calculated as the in-plane surface roughness Ra(S) of that block facing end face.
  • Ra(D)/Ra(S) of the same block opposing end face was calculated from the lamination direction surface roughness Ra(D) and the in-plane direction surface roughness Ra(S) of that block opposing end face. This calculation of Ra(D)/Ra(S) was performed for all block opposing end faces 111a to 111p of all stacked cores 100 manufactured as described above.
  • Tables 3 and 4 show the n/L, Ra(D)/Ra(S) and noise values of each stacked core 100 obtained in this manner.
  • 111a to 111p indicate the block facing end surfaces 111a to 111p shown in Figures 1, 2A to 2E, 3A to 3E, and 4A to 4E.
  • steel types B to E in which the number of crystal grains per unit length on the opposing end faces of the steel plate, n/L, is 0.5 or less, have lower noise levels than steel type A, in which the number is over 0.5.
  • numbers 25 to 28 have lower noise levels than number 4 (steel type A).
  • numbers 29 to 32 have lower noise levels than number 12 (steel type A).
  • numbers 33 to 36 have lower noise levels than number 13 (steel type A).
  • noise was reduced in numbers 45 and 46 (steel types A and B) compared to number 2 (steel type A). Noise was reduced in number 47 (numbers B and C) compared to numbers 21 (steel type B) and 22 (steel type C). Noise was reduced in number 48 (numbers B and E) compared to numbers 21 (steel type B) and 26 (steel type E).
  • the present invention can be used, for example, in equipment that has an iron core.

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Abstract

1 < Ra(D)/Ra(S) ≦ 12 is satisfied in each of at least one pair of block opposing end faces (for example, a pair of block opposing end faces (111a, 111i)). Here, Ra(D) is the surface roughness of the block opposing end face in the stacking direction. Ra(S) is the surface roughness in the main magnetic flux direction (or rolling direction) of the plate surface of a steel plate having an end face that configures a part of the block opposing end face.

Description

積鉄心および積鉄心の製造方法Stacked core and method of manufacturing stacked core
　本発明は、積鉄心および積鉄心の製造方法に関する。本願は、２０２２年１０月３日に日本に出願された特願２０２２－１５９５３２号に基づき優先権を主張し、その内容を全てここに援用する。 The present invention relates to a stacked core and a method for manufacturing a stacked core. This application claims priority to Japanese Patent Application No. 2022-159532, filed on October 3, 2022, the contents of which are incorporated herein by reference in their entirety.
　複数の鋼板を積層することにより構成される積鉄心は、積層された各鋼板が励磁時に振動する。各鋼板が振動することにより、積鉄心から騒音が発生する虞がある。そこで、このような鋼板の振動を抑制するための技術が求められる。この種の技術として特許文献１～４に記載の技術がある。 In a stacked core made by stacking multiple steel plates, each stacked steel plate vibrates when excited. There is a risk that noise will be generated from the stacked core due to the vibration of each steel plate. Therefore, technology is required to suppress such vibration of steel plates. Examples of this type of technology are described in Patent Documents 1 to 4.
　特許文献１には、積層された複数の電磁鋼板の間に制振鋼板を部分的に介在させることが開示されている。
　特許文献２には、各電磁鋼板の板面に加工溝を施した後、加工溝が施されていない板面同士が重ならないように複数の電磁鋼板を積層することが開示されている。また、特許文献２には、積層された複数の電磁鋼板の端面に接着性樹脂を塗布することが開示されている。 Patent Document 1 discloses partially interposing vibration-damping steel sheets between a plurality of laminated electromagnetic steel sheets.
Patent Literature 2 discloses that after forming grooves on the sheet surface of each electromagnetic steel sheet, multiple electromagnetic steel sheets are stacked so that the sheet surfaces not formed with the grooves do not overlap each other. Patent Literature 2 also discloses that an adhesive resin is applied to the end surfaces of the multiple stacked electromagnetic steel sheets.
　特許文献３には、鉄心の外周を構成する平面に、当該平面の長手方向に沿って圧縮変形された応力部材を設けることが開示されている。
　特許文献４には、Ｓｉを４．９～７．１％含有する絶縁コーティングであって、表面粗度がＲｍａｘで３．５μｍ以上の絶縁コーティングをそれぞれが有する複数の電磁鋼板を積層することが開示されている。また、特許文献４には、積層された複数の電磁鋼板の間に、接着機能を兼ねた含浸剤を挿入することが開示されている。 Patent Document 3 discloses providing a stress member that is compressively deformed along the longitudinal direction of a plane that constitutes the outer periphery of an iron core.
Patent Document 4 discloses stacking a plurality of electrical steel sheets, each having an insulating coating containing 4.9 to 7.1% Si and having a surface roughness Rmax of 3.5 μm or more, and also discloses inserting an impregnating agent, which also functions as an adhesive, between the stacked electrical steel sheets.
特開２００６－１４５５５号公報JP 2006-14555 A 特開２００３－７７７４７号公報JP 2003-77747 A 特開２０００－１１４０６４号公報JP 2000-114064 A 特開平４－３６１５０８号公報Japanese Patent Application Laid-Open No. 4-361508
　しかしながら、特許文献１～４に記載の技術では、積鉄心の振動を抑制するために鋼板とは別の材料が必要になる。
　本発明は、以上のような問題点に鑑みてなされたものであり、鋼板とは別の材料を用いなくても振動を抑制することができる積鉄心を提供することを目的とする。 However, the techniques described in Patent Documents 1 to 4 require a material other than the steel sheet to suppress vibration of the stacked core.
The present invention has been made in consideration of the above problems, and has an object to provide a stacked core that can suppress vibration without using a material other than steel sheets.
　本発明の積鉄心は、積層された複数の鋼板をそれぞれが有する複数のブロックを備え、前記複数のブロックは、ブロック対向端面を有し、前記ブロック対向端面は、前記ブロックの端面のうち、他の前記ブロックと相互に対向する位置にある端面であり、少なくとも一つの一対の前記ブロック対向端面のそれぞれにおいて、以下の（Ａ）式を満たし、前記一対のブロック対向端面は、相互に対向する位置に配置される二つの前記ブロック対向端面であることを特徴とする。
　１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２　・・・（Ａ）
　ここで、Ｒａ（Ｄ）は、前記ブロック対向端面の、前記鋼板の積層方向における表面粗さＲａ（μｍ）であり、Ｒａ（Ｓ）は、当該ブロック対向端面の一部を構成する端面を有する前記鋼板の板面の、当該鋼板に流れる主磁束の方向または当該鋼板の圧延方向における表面粗さＲａ（μｍ）である。 The stacked core of the present invention comprises a plurality of blocks, each having a plurality of stacked steel plates, the plurality of blocks having block opposing end faces, the block opposing end faces being end faces among the end faces of the blocks that are positioned opposite each other of the blocks, and each of at least one pair of the block opposing end faces satisfies the following formula (A), and the pair of block opposing end faces are two of the block opposing end faces that are arranged in positions opposite each other.
1<Ra(D)/Ra(S)≦12 ... (A)
Here, Ra(D) is the surface roughness Ra (μm) of the block-facing end face in the stacking direction of the steel plate, and Ra(S) is the surface roughness Ra (μm) of the plate surface of the steel plate having an end face that constitutes part of the block-facing end face, in the direction of the main magnetic flux flowing through the steel plate or the rolling direction of the steel plate.
　本発明の積鉄心の製造方法は、積層された複数の鋼板をそれぞれが有する複数のブロックを備えた積鉄心の製造方法であって、鋼板を切断する切断工程と、前記切断工程で切断された鋼板の板面の表面粗さＲａ（Ｓ）（μｍ）を測定する第１粗さ測定工程と、前記表面粗さＲａ（Ｓ）の測定対象の前記鋼板を有する前記ブロックのブロック対向端面の表面粗さＲａ（Ｄ）（μｍ）を測定する第２粗さ測定工程と、前記第１粗さ測定工程により測定されたＲａ（Ｓ）に対する前記第２粗さ測定工程により測定された表面粗さＲａ（Ｄ）の比Ｒａ（Ｄ）／Ｒａ（Ｓ）が、１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２を満たさない場合、前記ブロック対向端面の表面粗さを調整する粗さ調整工程と、を備え、前記表面粗さＲａ（Ｓ）は、前記積鉄心が励磁された場合に前記鋼板に流れる主磁束の方向における表面粗さＲａ（μｍ）、または、前記鋼板の圧延方向における表面粗さＲａ（μｍ）であり、前記表面粗さＲａ（Ｄ）は、前記鋼板の積層方向における表面粗さＲａ（μｍ）であり、前記ブロック対向端面は、前記ブロックの端面のうち、前記積鉄心において他の前記ブロックと相互に対向する位置にある端面であり、前記粗さ調整工程では、少なくとも一つの一対の前記ブロック対向端面のそれぞれにおいて、１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２を満たすように、前記ブロック対向端面の表面粗さを調整し、前記一対のブロック対向端面は、相互に対向する位置に配置される二つの前記ブロック対向端面である。 The method for manufacturing a stacked core of the present invention is a method for manufacturing a stacked core having a plurality of blocks each having a plurality of stacked steel plates, and includes a cutting process for cutting the steel plate, a first roughness measurement process for measuring the surface roughness Ra(S) (μm) of the plate surface of the steel plate cut in the cutting process, a second roughness measurement process for measuring the surface roughness Ra(D) (μm) of the block-facing end surface of the block having the steel plate to be measured for the surface roughness Ra(S), and a roughness adjustment process for adjusting the surface roughness of the block-facing end surface when the ratio Ra(D)/Ra(S) of the surface roughness Ra(D) measured in the second roughness measurement process to the Ra(S) measured in the first roughness measurement process does not satisfy 1<Ra(D)/Ra(S)≦12, The roughness Ra(S) is the surface roughness Ra(μm) in the direction of the main magnetic flux flowing through the steel plate when the stacked core is excited, or the surface roughness Ra(μm) in the rolling direction of the steel plate, the surface roughness Ra(D) is the surface roughness Ra(μm) in the lamination direction of the steel plate, the block facing end face is an end face of the block that is located opposite the other block in the stacked core, and in the roughness adjustment process, the surface roughness of at least one pair of the block facing end faces is adjusted so that 1<Ra(D)/Ra(S)≦12 is satisfied, and the pair of block facing end faces are two block facing end faces that are located opposite each other.
図１は、積鉄心の一例を示す図である。FIG. 1 is a diagram showing an example of a stacked core. 図２Ａは、積層方向表面粗さの測定位置の第１の例を説明する図である。FIG. 2A is a diagram illustrating a first example of measurement positions for the surface roughness in the lamination direction. 図２Ｂは、積層方向表面粗さの測定位置の第２の例を説明する図である。FIG. 2B is a diagram illustrating a second example of the measurement positions for the surface roughness in the lamination direction. 図２Ｃは、積層方向表面粗さの測定位置の第３の例を説明する図である。FIG. 2C is a diagram illustrating a third example of the measurement positions of the surface roughness in the lamination direction. 図２Ｄは、積層方向表面粗さの測定位置の第４の例を説明する図である。FIG. 2D is a diagram illustrating a fourth example of the measurement positions of the surface roughness in the lamination direction. 図２Ｅは、積層方向表面粗さの測定位置の第５の例を説明する図である。FIG. 2E is a diagram illustrating a fifth example of the measurement positions of the surface roughness in the stacking direction. 図３Ａは、面内方向表面粗さの測定位置の第１の例を説明する図である。FIG. 3A is a diagram illustrating a first example of measurement positions for in-plane surface roughness. 図３Ｂは、面内方向表面粗さの測定位置の第２の例を説明する図である。FIG. 3B is a diagram illustrating a second example of the measurement positions for the in-plane surface roughness. 図３Ｃは、面内方向表面粗さの測定位置の第３の例を説明する図である。FIG. 3C is a diagram illustrating a third example of the measurement positions of the in-plane surface roughness. 図３Ｄは、面内方向表面粗さの測定位置の第４の例を説明する図である。FIG. 3D is a diagram illustrating a fourth example of the measurement positions for the in-plane surface roughness. 図３Ｅは、面内方向表面粗さの測定位置の第５の例を説明する図である。FIG. 3E is a diagram illustrating a fifth example of the measurement positions for the in-plane surface roughness. 図４Ａは、鋼板対向端面上の結晶粒の数および鋼板対向端面の長さの第１の例を説明する図である。FIG. 4A is a diagram illustrating a first example of the number of crystal grains on the opposing end surface of a steel sheet and the length of the opposing end surface of a steel sheet. 図４Ｂは、鋼板対向端面上の結晶粒の数および鋼板対向端面の長さの第２の例を説明する図である。FIG. 4B is a diagram illustrating a second example of the number of crystal grains on the opposing end surface of the steel sheet and the length of the opposing end surface of the steel sheet. 図４Ｃは、鋼板対向端面上の結晶粒の数および鋼板対向端面の長さの第３の例を説明する図である。FIG. 4C is a diagram illustrating a third example of the number of crystal grains on the opposing end surface of the steel sheet and the length of the opposing end surface of the steel sheet. 図４Ｄは、鋼板対向端面上の結晶粒の数および鋼板対向端面の長さの第４の例を説明する図である。FIG. 4D is a diagram illustrating a fourth example of the number of crystal grains on the opposing end surface of the steel sheet and the length of the opposing end surface of the steel sheet. 図４Ｅは、鋼板対向端面上の結晶粒の数および鋼板対向端面の長さの第５の例を説明する図である。FIG. 4E is a diagram illustrating a fifth example of the number of crystal grains on the opposing end surface of the steel sheet and the length of the opposing end surface of the steel sheet. 積鉄心の製造方法の一例を示すフローチャートである。4 is a flowchart showing an example of a method for manufacturing a stacked core.
　以下、図面を参照しながら、本発明の一実施形態を説明する。
　なお、長さ、位置、大きさ、間隔等、比較対象が同じであることは、厳密に同じである場合の他、発明の主旨を逸脱しない範囲で異なるもの（例えば、設計時に定められる公差の範囲内で異なるもの）も含むものとする。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In addition, the term "compared objects" including length, position, size, spacing, etc., being the same includes not only objects that are strictly the same, but also objects that are different within the scope of the invention (for example, objects that differ within the tolerance range determined at the time of design).
　図１は、積鉄心１００の一例を示す図である。なお、図１に示すｘ－ｙ－ｚ座標は、各部の向きを説明するために便宜的に示すものである。図１に示す積鉄心１００は、例えば、三相交流電流が流れるコイルが巻き回される積鉄心（いわゆる三相積鉄心）である。なお、積鉄心１００に巻き回されるコイルに流れる電流は、三相交流電流に限定されない。例えば、積鉄心１００に巻き回されるコイルに流れる電流は、単相交流電流でも良い。また、積鉄心１００は、各種の機器が備える鉄心として用いれられる。積鉄心１００は、例えば、変圧器、変流器、回転電機、およびリアクトルが備える鉄心でも良い。 FIG. 1 is a diagram showing an example of a stacked core 100. Note that the x-y-z coordinates shown in FIG. 1 are shown for convenience in explaining the orientation of each part. The stacked core 100 shown in FIG. 1 is, for example, a stacked core (a so-called three-phase stacked core) around which a coil through which a three-phase AC current flows is wound. Note that the current flowing through the coil wound around the stacked core 100 is not limited to three-phase AC. For example, the current flowing through the coil wound around the stacked core 100 may be a single-phase AC current. The stacked core 100 is also used as an iron core provided in various devices. The stacked core 100 may be, for example, an iron core provided in a transformer, a current transformer, a rotating electric machine, and a reactor.
　図１において、積鉄心１００は、複数のブロック１１０ａ～１１０ｅを備える。複数のブロック１１０ａ～１００ｅはそれぞれ、板面が相互に対向するように積層された複数の鋼板を有する。 In FIG. 1, stacked core 100 comprises multiple blocks 110a to 110e. Each of blocks 110a to 110e has multiple steel plates stacked together with their plate surfaces facing each other.
　図１において、複数のブロック１１０ａ～１１０ｅ内に示す両矢印線は、当該ブロック１１０ａ～１１０ｅが励磁されたときに鋼板に流れる主磁束の方向または圧延方向を示す。以下の説明では、ブロック１１０ａ～１１０ｅが励磁されたときに鋼板に流れる主磁束の方向を、必要に応じて主磁束方向と称する。 In FIG. 1, the double-arrowed lines shown within multiple blocks 110a-110e indicate the direction of the main magnetic flux flowing through the steel sheet when the blocks 110a-110e are excited, or the rolling direction. In the following explanation, the direction of the main magnetic flux flowing through the steel sheet when the blocks 110a-110e are excited will be referred to as the main magnetic flux direction as necessary.
　なお、主磁束方向は、各ブロックに流れる主磁束のうち、他のブロックとの流出入により方向が変わる領域での主磁束を除いて定められるものとする（すなわち、主磁束方向は主磁束が直進する方向である）。鋼板が一方向性電磁鋼板である場合、主磁束方向と圧延方向とが可及的に近くなるのが好ましく、一致するのがより好ましい。また、鋼板が一方向性電磁鋼板である場合、圧延方向と磁化容易方向（磁化容易軸に平行な方向）とが可及的に近くなるのが好ましく、一致するのがより好ましい。 The main magnetic flux direction is determined by excluding the main magnetic flux flowing in each block in areas where the direction changes due to flow in and out of other blocks (i.e., the main magnetic flux direction is the direction in which the main magnetic flux travels straight). If the steel sheet is a grain-oriented electromagnetic steel sheet, it is preferable that the main magnetic flux direction and the rolling direction are as close as possible, and it is more preferable that they coincide. Also, if the steel sheet is a grain-oriented electromagnetic steel sheet, it is preferable that the rolling direction and the easy magnetization direction (direction parallel to the easy magnetization axis) are as close as possible, and it is more preferable that they coincide.
　以下の説明において、複数のブロック１１０ａ～１１０ｅ内に示す両矢印線の方向が鋼板の圧延方向に略平行（好ましくは平行）となるように鋼板が積層されている場合には、主磁束方向（または圧延方向）は、主磁束方向および圧延方向のいずれの方向であって良いことを意味する。一方、複数のブロック１１０ａ～１１０ｅ内に示す両矢印線の方向が鋼板の圧延方向に略平行（好ましくは平行）となるように鋼板が積層されていない場合には、主磁束方向（または圧延方向）は、主磁束方向であることを意味する。圧延方向は、鋼板の板面を観察すれば特定されるので、圧延方向の特定は容易である。 In the following description, if the steel plates are stacked so that the direction of the double-headed arrows shown in the multiple blocks 110a to 110e is approximately parallel (preferably parallel) to the rolling direction of the steel plates, this means that the main magnetic flux direction (or rolling direction) can be either the main magnetic flux direction or the rolling direction. On the other hand, if the steel plates are not stacked so that the direction of the double-headed arrows shown in the multiple blocks 110a to 110e is approximately parallel (preferably parallel) to the rolling direction of the steel plates, this means that the main magnetic flux direction (or rolling direction) is the main magnetic flux direction. The rolling direction can be determined by observing the surface of the steel plates, so it is easy to determine the rolling direction.
　本実施形態では、積鉄心１００は、その中心線ＣＬを回転対称軸とする二回対称の関係になるように構成される。中心線ＣＬは、積鉄心１００の重心の位置を通り、且つ、積鉄心１００を構成する鋼板の積層方向（ｚ軸方向）に延びる仮想直線である。以下の説明では、積鉄心１００を構成する鋼板の積層方向を、必要に応じて積層方向と略称する。 In this embodiment, the stacked core 100 is configured to have a two-fold symmetric relationship with its center line CL as the axis of rotational symmetry. The center line CL is an imaginary straight line that passes through the position of the center of gravity of the stacked core 100 and extends in the stacking direction (z-axis direction) of the steel plates that make up the stacked core 100. In the following description, the stacking direction of the steel plates that make up the stacked core 100 will be abbreviated to the stacking direction as necessary.
　また、本実施形態では、鋼種および板厚が同一の複数の一方向性電磁鋼板を積層することにより複数のブロック１１０ａ～１１０ｅが構成される場合を例示する。ただし、鋼板は、一方向性電磁鋼板に限定されない。鋼板は、例えば、二方向性電磁鋼板であっても良い。また、鋼板は、無方向性電磁鋼板であっても良い。また、複数のブロックのうちの少なくとも二つのブロックを構成する鋼板の鋼種および板厚のうちの少なくとも一方は異なっていても良い。また、一つのブロックを構成する複数の鋼板の鋼種および板厚のうちの少なくとも一方は異なっていても良い。また、本実施形態では、複数のブロック１１０ａ～１１０ｅの厚み（積層方向（ｚ軸方向）の長さ）が同じである場合を例示する。また、本実施形態では、ブロック１１０ａ～１１０ｂが、中心線ＣＬを回転対称軸とする二回対称の関係になるように構成および配置される場合を例示する。同様に、ブロック１１０ｃ～１１０ｄも、中心線ＣＬを回転対称軸とする二回対称の関係になるように構成および配置される場合を例示する。
　なお、ブロックの数、形状、大きさ、および配置は、積鉄心を備える機器の仕様に応じて定められる。したがって、ブロックの数、形状、大きさ、および配置は、図１に例示するものに限定されない。 In addition, in this embodiment, a case where a plurality of blocks 110a to 110e are configured by stacking a plurality of grain-oriented electromagnetic steel sheets having the same steel type and sheet thickness is illustrated. However, the steel sheets are not limited to grain-oriented electromagnetic steel sheets. The steel sheets may be, for example, bi-directional electromagnetic steel sheets. The steel sheets may be non-oriented electromagnetic steel sheets. At least one of the steel types and sheet thicknesses of the steel sheets configuring at least two of the plurality of blocks may be different. At least one of the steel types and sheet thicknesses of the plurality of steel sheets configuring one block may be different. In addition, in this embodiment, a case where the thicknesses (lengths in the stacking direction (z-axis direction)) of the plurality of blocks 110a to 110e are the same is illustrated. In addition, in this embodiment, a case where the blocks 110a to 110b are configured and arranged to have a two-fold symmetric relationship with the center line CL as the axis of rotational symmetry is illustrated. Similarly, a case where the blocks 110c to 110d are configured and arranged to have a two-fold symmetric relationship with the center line CL as the axis of rotational symmetry is illustrated.
The number, shape, size, and arrangement of the blocks are determined according to the specifications of the device that includes the stacked core, and therefore are not limited to those illustrated in FIG.
　複数のブロック１１０ａ～１１０ｅの端面には、ブロック対向端面１１１ａ～１１１ｐが含まれる。ブロック１１０ａ～１１０ｅのブロック対向端面１１１ａ～１１１ｐは、ブロック１１０ａ～１１０ｅの端面のうち、他のブロックと相互に対向する位置にある端面である。図１に示す例では、ブロック１１０ａの端面にはブロック対向端面１１１ａ～１１１ｄが含まれる。また、ブロック１１０ｂの端面にはブロック対向端面１１１ｅ～１１１ｈが含まれる。また、ブロック１１０ｃの端面にはブロック対向端面１１１ｉ～１１１ｊが含まれる。また、ブロック１１０ｄの端面にはブロック対向端面１１１ｋ～１１１ｌが含まれる。また、ブロック１１０ｅの端面にはブロック対向端面１１１ｏ～１１１ｐが含まれる。 The end faces of the multiple blocks 110a to 110e include block-facing end faces 111a to 111p. The block-facing end faces 111a to 111p of the blocks 110a to 110e are the end faces of the blocks 110a to 110e that are positioned opposite each other. In the example shown in FIG. 1, the end faces of the block 110a include block-facing end faces 111a to 111d. The end faces of the block 110b include block-facing end faces 111e to 111h. The end faces of the block 110c include block-facing end faces 111i to 111j. The end faces of the block 110d include block-facing end faces 111k to 111l. The end faces of the block 110e include block-facing end faces 111o to 111p.
　相互に対向する位置に配置される二つのブロック対向端面を一対のブロック対向端面と称することとする。例えば、ブロック１１０ａが有するブロック対向端面１１１ａと、ブロック１１０ｃが有するブロック対向端面１１１ｉと、は相互に対向する位置に配置される。したがって、これらのブロック対向端面１１１ａおよび１１１ｉは、一対のブロック対向端面１１１ａおよび１１１ｉである。図１に例示する積鉄心１００には、一対のブロック対向端面１１１ａおよび１１１ｉ、１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐが八つ存在する。ここで、一対のブロック対向端面（例えば、ブロック対向端面１１１ａおよび１１１ｉ）は、いわゆる突合部である。したがって、一対のブロック対向端面（二つのブロック対向端面）の一部または全部の領域は相互に接触している。 Two block opposing end faces arranged in a mutually opposing position are referred to as a pair of block opposing end faces. For example, block opposing end face 111a of block 110a and block opposing end face 111i of block 110c are arranged in a mutually opposing position. Therefore, these block opposing end faces 111a and 111i are a pair of block opposing end faces 111a and 111i. The stacked core 100 illustrated in FIG. 1 has eight pairs of block opposing end faces: 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p. Here, a pair of block opposing end faces (for example, block opposing end faces 111a and 111i) is a so-called butt portion. Therefore, some or all of the areas of a pair of opposing end faces of blocks (two opposing end faces of blocks) are in contact with each other.
　図１において、ブロック対向端面１１１ａ～１１１ｐは、積層方向（ｚ軸方向）から積鉄心１００を見た場合に見えるブロック対向端面１１１ａ～１１１ｐを示す線を直線近似した場合に表われる屈曲点において区切られる（図１に示すブロック対向端面１１１ｃおよび１１１ｄ、１１１ｇおよび１１１ｈ、１１１ｍおよび１１１ｎ、１１１ｏおよび１１１ｐを参照）。 In FIG. 1, block opposing end faces 111a to 111p are separated by bending points that appear when linear approximations of lines representing block opposing end faces 111a to 111p that can be seen when stacked core 100 is viewed from the stacking direction (z-axis direction) are made (see block opposing end faces 111c and 111d, 111g and 111h, 111m and 111n, and 111o and 111p shown in FIG. 1).
　なお、積層方向（ｚ軸方向）から積鉄心１００を見た場合に見えるブロック対向端面１１１ａ～１１１ｐを示す線を直線近似するよりも曲線近似（例えば２次関数で近似）する方が当該線を高精度に近似することができる場合、当該曲線近似した場合の極値を示す位置でブロック対向端面を区切っても良い。 In addition, if the line showing the block opposing end faces 111a to 111p that can be seen when viewing the stacked core 100 from the stacking direction (z-axis direction) can be more accurately approximated by curve approximation (for example, approximation with a quadratic function) rather than linear approximation, the block opposing end faces may be divided at the positions that show the extreme values of the curve approximation.
　以下に、本発明者らが見出した知見とともに本実施形態の積鉄心１００について説明する。ここでは説明を分かりやすくするために、図１に示す符号を付して、本発明者らが見出した知見を説明する。しかしながら、本発明者らが見出した知見は、図１に示す積鉄心１００に限定される知見ではない。 Below, the stacked core 100 of this embodiment will be described along with the findings of the inventors. For ease of understanding, the findings of the inventors will be described using the symbols shown in FIG. 1. However, the findings of the inventors are not limited to the stacked core 100 shown in FIG. 1.
　ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）での振動が積鉄心１００の騒音に大きく影響を与える。本発明者らは、このようなブロック１１０ａ～１１０ｅの突合部での振動を、鋼板とは別の材料を用いずに抑制するために、鋼板の形状に着目した。そして、本発明者らは、ブロック対向端面１１１ａ～１１１ｐの粗さを適正化することにより、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）での振動を抑制することで、積鉄心１００の騒音を抑制することができることを見出した。 Vibrations at the butt joints of blocks 110a to 110e (block opposing end faces 111a to 111p) have a large impact on the noise of stacked core 100. The inventors focused on the shape of the steel plates in order to suppress such vibrations at the butt joints of blocks 110a to 110e without using a material other than the steel plates. The inventors then discovered that by optimizing the roughness of block opposing end faces 111a to 111p, it is possible to suppress the noise of stacked core 100 by suppressing vibrations at the butt joints of blocks 110a to 110e (block opposing end faces 111a to 111p).
　具体的に本発明者らは、複数の一対のブロック対向端面１１１ａおよび１１１ｉ、１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐのうちの少なくとも一つの一対のブロック対向端面（二つのブロック対向端面）のそれぞれにおいて、以下の（１）式を満たすことにより、ブロックの突合部（ブロック対向端面）の振動を抑制することができることを見出した。
　１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２　・・・（１） Specifically, the inventors have discovered that vibration of the block butt joints (block opposing end faces) can be suppressed by satisfying the following formula (1) in at least one pair of block opposing end faces (two block opposing end faces) among multiple pairs of block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
1<Ra(D)/Ra(S)≦12 ... (1)
　ここで、Ｒａ（Ｄ）は、（１）式の算出対象の一対のブロック対向端面（二つのブロック対向端面）のうちの一つのブロック対向端面の積層方向（ｚ軸方向）における表面粗さＲａ（μｍ）である。以下の説明では、このようにしてブロック対向端面ごとに定められる表面粗さを、必要に応じて積層方向表面粗さと称する。また、Ｒａ（Ｓ）は、当該ブロック対向端面の一部を構成する端面を有する鋼板の板面の主磁束方向（または鋼板の圧延方向）における表面粗さＲａ（μｍ）である。以下の説明では、このようにして定められる表面粗さを、必要に応じて面内方向表面粗さと称する。表面粗さＲａ（積層方向表面粗さＲａ（Ｄ）および面内方向表面粗さＲａ（Ｓ））は、ＪＩＳ　Ｂ　０６０１：２０１３で定められている粗さ曲線要素の平均高さＲｃであるものとする。なお、ブロック対向端面は、積層された複数の鋼板の端面から構成される。ブロック対向端面の一部を構成する端面は、当該複数の鋼板のうちの一つの鋼板の端面である。また、Ｒａ（μｍ）の（μｍ）は、表面粗さＲａの単位がマイクロメートルであることを示す（このような単位の表記の方法はその他の変数ｎ、Ｌ、ｎ／Ｌにおいても同じである）。面内方向表面粗さＲａ（Ｓ）は、例えば、０．１０μｍ以上３．００μｍ以下である。 Here, Ra(D) is the surface roughness Ra (μm) in the lamination direction (z-axis direction) of one of the pair of block opposing end faces (two block opposing end faces) to be calculated using formula (1). In the following description, the surface roughness determined for each block opposing end face in this manner is referred to as lamination direction surface roughness as necessary. Also, Ra(S) is the surface roughness Ra (μm) in the main magnetic flux direction (or the rolling direction of the steel plate) of the plate surface having an end face that constitutes a part of the block opposing end face. In the following description, the surface roughness determined in this manner is referred to as in-plane direction surface roughness as necessary. The surface roughness Ra (lamination direction surface roughness Ra(D) and in-plane direction surface roughness Ra(S)) is the average height Rc of the roughness curve element defined in JIS B 0601:2013. The block opposing end face is composed of the end faces of multiple stacked steel plates. The end face constituting a part of the block facing end face is the end face of one of the multiple steel plates. The (μm) in Ra(μm) indicates that the unit of surface roughness Ra is micrometers (this method of expressing units is the same for the other variables n, L, and n/L). The in-plane surface roughness Ra(S) is, for example, 0.10 μm or more and 3.00 μm or less.
　例えば、（１）式の算出対象の一対のブロック対向端面（二つのブロック対向端面）が一対のブロック対向端面１１１ａおよび１１１ｉであるとする。この場合、ブロック対向端面１１１ａ、１１１ｉのそれぞれについて（１）式を満たせば、一つの一対のブロック対向端面１１１ａおよび１１１ｉのそれぞれにおいて（１）式を満たすことになる。その他の一対のブロック対向端面１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐについても同様にして（１）式を満たすか否かが判定される。 For example, assume that the pair of block opposing end faces (two block opposing end faces) for which formula (1) is calculated are the pair of block opposing end faces 111a and 111i. In this case, if formula (1) is satisfied for each of block opposing end faces 111a and 111i, then formula (1) is satisfied for each of one pair of block opposing end faces 111a and 111i. Whether formula (1) is satisfied is similarly determined for the other pairs of block opposing end faces 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
　図２Ａ～図２Ｅは、積層方向表面粗さＲａ（Ｄ）の測定位置の一例を説明する図である。図２Ａおよび図２Ｄに示すｙ－ｚ座標は、図１に示すｘ－ｙ－ｚ座標のｙ座標およびｚ座標に対応する。図２Ｂ、図２Ｃ、および図２Ｅに示すｘ－ｚ座標は、図１に示すｘ－ｙ－ｚ座標のｘ座標およびｚ座標に対応する。前述したように図２Ａに示すブロック１１０ａと図２Ｄに示すブロック１１０ｂとは、積鉄心１００の中心線ＣＬを回転対称軸とする二回対称の関係になるように構成および配置される。同様に、図２Ｂに示すブロック１１０ｃと図２Ｄに示すブロック１１０ｄも、積鉄心１００の中心線ＣＬを回転対称軸とする二回対称の関係になるように構成および配置される。 2A to 2E are diagrams for explaining an example of the measurement position of the surface roughness Ra(D) in the lamination direction. The y-z coordinates shown in Fig. 2A and Fig. 2D correspond to the y and z coordinates of the x-y-z coordinate system shown in Fig. 1. The x-z coordinates shown in Fig. 2B, Fig. 2C, and Fig. 2E correspond to the x and z coordinates of the x-y-z coordinate system shown in Fig. 1. As described above, block 110a shown in Fig. 2A and block 110b shown in Fig. 2D are configured and arranged to have a two-fold symmetric relationship with the center line CL of stacked core 100 as the axis of rotational symmetry. Similarly, block 110c shown in Fig. 2B and block 110d shown in Fig. 2D are configured and arranged to have a two-fold symmetric relationship with the center line CL of stacked core 100 as the axis of rotational symmetry.
　図２Ａおよび図２Ｄは、ブロック１１０ａ、１１０ｂが有するブロック対向端面１１１ａ～１１１ｄ、１１１ｅ～１１１ｈの積層方向表面粗さＲａ（Ｄ）の測定位置の一例を示す図である。図２Ｂおよび図２Ｅは、ブロック１１０ｃ、１１０ｄが有するブロック対向端面１１１ｉ～１１１ｊ、１１１ｋ～１１１ｌの積層方向表面粗さＲａ（Ｄ）の測定位置の一例を示す図である。図２Ｃは、ブロック１１０ｅが有するブロック対向端面１１１ｍ～１１１ｐの積層方向表面粗さＲａ（Ｄ）の測定位置の一例を示す図である。 FIGS. 2A and 2D are diagrams showing an example of measurement positions for the stacking direction surface roughness Ra(D) of block facing end faces 111a-111d, 111e-111h of blocks 110a, 110b. FIGS. 2B and 2E are diagrams showing an example of measurement positions for the stacking direction surface roughness Ra(D) of block facing end faces 111i-111j, 111k-111l of blocks 110c, 110d. FIG. 2C is a diagram showing an example of measurement positions for the stacking direction surface roughness Ra(D) of block facing end faces 111m-111p of block 110e.
　積層方向表面粗さＲａ（Ｄ）は、（１）式の算出対象の一対のブロック対向端面において、当該ブロック対向端面の一部を構成する端面を有する鋼板の積層方向から当該ブロック対向端面を見た場合の当該ブロック対向端面の両端の中心の位置を通る仮想直線上で測定される。 The surface roughness in the lamination direction, Ra(D), is measured on an imaginary straight line passing through the center positions of both ends of the opposing block end faces of the pair of opposing block end faces to be calculated using formula (1) when the opposing block end faces are viewed from the lamination direction of the steel plate having an end face that constitutes part of the opposing block end faces.
　図１に示す例では、ブロック対向端面１１１ａ～１１１ｐの一部を構成する端面を有する鋼板の積層方向はｚ軸方向である。図１において、ブロック対向端面１１１ａおよび１１１ｉ、１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐをｚ軸方向から見た場合の、当該ブロック対向端面の両端１１３ａおよび１１３ｂ、１１３ｃおよび１１３ｄ、１１３ｅおよび１１３ｆ、１１３ｆおよび１１３ｇ、１１３ｈおよび１１３ｉ、１１３ｊおよび１１３ｋ、１１３ｅおよび１１３ｆ、１１３ｆおよび１１３ｇ、１１３ｌおよび１１３ｍ、１１３ｍおよび１１３ｎの中心の位置は、それぞれ位置１１２ａ、１１２ｂ、１１２ｃ、１１２ｄ、１１２ｅ、１１２ｆ、１１２ｇ、１１２ｈである。当該ブロック対向端面の両端の中心の位置は、積層方向（ｚ軸方向）のそれぞれにおいて得られる。このような当該ブロック対向端面の両端の中心の位置を辿ると、図２Ａ～図２Ｅに示すように仮想直線２０１ａ～２０１ｐが得られる。 In the example shown in Figure 1, the stacking direction of the steel plates having end faces that form part of the block opposing end faces 111a to 111p is the z-axis direction. In FIG. 1, when block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p are viewed from the z-axis direction, the positions of the centers of both ends 113a and 113b, 113c and 113d, 113e and 113f, 113f and 113g, 113h and 113i, 113j and 113k, 113e and 113f, 113f and 113g, 113l and 113m, and 113m and 113n are positions 112a, 112b, 112c, 112d, 112e, 112f, 112g, and 112h, respectively. The center positions of both ends of the opposing block end faces are obtained in the stacking direction (z-axis direction). By tracing the center positions of both ends of the opposing block end faces, virtual straight lines 201a to 201p are obtained as shown in Figures 2A to 2E.
　したがって、（１）式の算出対象の一対のブロック対向端面が一対のブロック対向端面１１１ａおよび１１１ｉである場合、図２Ａおよび図２Ｂに示すように、ブロック対向端面１１１ａ、１１１ｉの積層方向表面粗さＲａ（Ｄ）は、それぞれ仮想直線２０１ａ、２０１ｅ上で測定される。また、（１）式の算出対象の一対のブロック対向端面が一対のブロック対向端面１１１ｂおよび１１１ｌである場合、図２Ａおよび図２Ｅに示すように、ブロック対向端面１１１ｂ、１１１ｌの積層方向表面粗さＲａ（Ｄ）を算出するための粗さ曲線は、それぞれ仮想直線２０１ｂ、２０１ｐ上で測定される。また、（１）式の算出対象の一対のブロック対向端面が一対のブロック対向端面１１１ｃおよび１１１ｍである場合、図２Ａおよび図２Ｃに示すように、ブロック対向端面１１１ｃ、１１１ｍの積層方向表面粗さＲａ（Ｄ）を算出するための粗さ曲線は、それぞれ仮想直線２０１ｃ、２０１ｇ上で測定される。また、（１）式の算出対象の一対のブロック対向端面が一対のブロック対向端面１１１ｄおよび１１１ｎである場合、図２Ａおよび図２Ｃに示すように、ブロック対向端面１１１ｄ、１１１ｎの積層方向表面粗さＲａ（Ｄ）を算出するための粗さ曲線は、それぞれ仮想直線２０１ｄ、２０１ｈ上で測定される。 Therefore, when the pair of block opposing end faces to be calculated using formula (1) are the pair of block opposing end faces 111a and 111i, the stacking direction surface roughness Ra(D) of block opposing end faces 111a and 111i is measured on imaginary straight lines 201a and 201e, respectively, as shown in Figures 2A and 2B. When the pair of block opposing end faces to be calculated using formula (1) are the pair of block opposing end faces 111b and 111l, the roughness curves for calculating the stacking direction surface roughness Ra(D) of block opposing end faces 111b and 111l are measured on imaginary straight lines 201b and 201p, respectively, as shown in Figures 2A and 2E. In addition, when the pair of block opposing end faces to be calculated using formula (1) are the pair of block opposing end faces 111c and 111m, as shown in Figures 2A and 2C, the roughness curves for calculating the stacking direction surface roughness Ra(D) of the block opposing end faces 111c and 111m are measured on the virtual straight lines 201c and 201g, respectively. In addition, when the pair of block opposing end faces to be calculated using formula (1) are the pair of block opposing end faces 111d and 111n, as shown in Figures 2A and 2C, the roughness curves for calculating the stacking direction surface roughness Ra(D) of the block opposing end faces 111d and 111n are measured on the virtual straight lines 201d and 201h, respectively.
　その他の一対のブロック対向端面１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐについても同様にして、仮想直線２０１ｋおよび２０１ｏ上、仮想直線２０１ｌおよび２０１ｆ上、仮想直線２０１ｍおよび２０１ｉ上、仮想直線２０１ｎおよび２０１ｊ上でそれぞれ積層方向表面粗さＲａ（Ｄ）を算出するための粗さ曲線が測定される。 　The same procedure is followed for the other pairs of opposing block end faces 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p, and roughness curves are measured to calculate the stacking direction surface roughness Ra(D) on the virtual straight lines 201k and 201o, 201l and 201f, 201m and 201i, and 201n and 201j, respectively.
　以下の説明では、積層方向表面粗さＲａ（Ｄ）を算出するための粗さ曲線（粗さ曲線要素）が測定される仮想直線２０１ａ～２０１ｐ上の位置を、必要に応じて積層方向測定位置と称する。図１に例示する積鉄心１００においては、積層方向測定位置は、図２Ａ～図２Ｅに示すように斜角切断面の位置になる。 In the following explanation, the positions on the imaginary straight lines 201a to 201p where the roughness curve (roughness curve element) for calculating the lamination direction surface roughness Ra(D) is measured will be referred to as lamination direction measurement positions as necessary. In the stacked core 100 illustrated in FIG. 1, the lamination direction measurement positions are the positions of the bevel cut surfaces as shown in FIGS. 2A to 2E.
　（１）式の算出対象の一対のブロック対向端面の一方のブロック対向端面を構成する複数の鋼板を一枚ずつ抜き取り、抜き取った鋼板の積層方向測定位置において積層方向表面粗さＲａ（Ｄ）を測定する。このようにすることに代えて、当該一方のブロック対向端面を有するブロックを構成するために用いる積層前の鋼板の積層方向測定位置において積層方向表面粗さＲａ（Ｄ）を測定しても良い。このような測定を当該一方のブロック対向端面を構成する全ての鋼板のそれぞれについて行う。例えば、積層枚数が２００枚である場合、一つのブロック対向端面について２００個の積層方向表面粗さＲａ（Ｄ）が測定される。以上のようにして測定された複数（前述の例では２００個）の積層方向表面粗さＲａ（Ｄ）の代表値を、当該一方のブロック対向端面の積層方向表面粗さＲａ（Ｄ）とする。代表値は、例えば、算術平均値である。算術平均値に代えて中央値等を用いても良い。（１）式の算出対象の一対のブロック対向端面の他方のブロック対向端面の積層方向表面粗さＲａ（Ｄ）も、一方のブロック対向端面の積層方向表面粗さＲａ（Ｄ）と同様にして算出する。 　The multiple steel plates constituting one of the pair of block opposing end faces to be calculated using formula (1) are extracted one by one, and the stacking direction surface roughness Ra (D) of the extracted steel plate is measured at the stacking direction measurement position. Alternatively, the stacking direction surface roughness Ra (D) of the steel plate before stacking used to construct the block having the one block opposing end face may be measured at the stacking direction measurement position. Such measurements are performed for all steel plates constituting the one block opposing end face. For example, if the number of stacked sheets is 200, 200 stacking direction surface roughnesses Ra (D) are measured for one block opposing end face. The representative value of the multiple stacking direction surface roughnesses Ra (D) measured in this manner (200 in the above example) is taken as the stacking direction surface roughness Ra (D) of the one block opposing end face. The representative value is, for example, the arithmetic mean value. Instead of the arithmetic mean value, a median value or the like may be used. The stacking direction surface roughness Ra(D) of the other block facing end face of the pair of block facing end faces being calculated using formula (1) is calculated in the same manner as the stacking direction surface roughness Ra(D) of one block facing end face.
　以上のようにして一対のブロック対向端面の一方および他方のブロック対向端面の積層方向表面粗さＲａ（Ｄ）を算出することを、ブロック対向端面１１１ａおよび１１１ｉ、１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐのそれぞれについて行う。 The lamination direction surface roughness Ra(D) of one and the other of a pair of block opposing end faces is calculated in the above manner for each of block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
　図３Ａ～図３Ｅは、面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線の測定位置の一例を説明する図である。図３Ａ～図３Ｅに示すｘ－ｙ座標は、図１に示すｘ－ｙ－ｚ座標のｘ座標およびｙ座標に対応する。 FIGS. 3A to 3E are diagrams illustrating an example of measurement positions of a roughness curve for calculating the in-plane surface roughness Ra(S). The x-y coordinates shown in FIG. 3A to FIG. 3E correspond to the x-coordinate and y-coordinate of the x-y-z coordinate system shown in FIG. 1.
　図３Ａ、図３Ｄは、ブロック１１０ａ、１１０ｂが有するブロック対向端面１１１ａ～１１１ｄ、１１１ｅ～１１１ｈの一部を構成する端面を有する鋼板の面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線の測定位置の一例を示す図である。図３Ｂ、図３Ｅは、ブロック１１０ｃ、１１０ｄが有するブロック対向端面１１１ｉ～１１１ｊ、１１１ｋ～１１１ｌの一部を構成する端面を有する鋼板の面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線の測定位置の一例を示す図である。図３Ｃは、ブロック１１０ｅが有するブロック対向端面１１１ｍ～１１１ｐの一部を構成する端面を有する鋼板の面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線の測定位置の一例を示す図である。 Figures 3A and 3D are diagrams showing an example of measurement positions of roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces constituting part of the block-facing end faces 111a-111d, 111e-111h of blocks 110a and 110b. Figures 3B and 3E are diagrams showing an example of measurement positions of roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces constituting part of the block-facing end faces 111i-111j, 111k-111l of blocks 110c and 110d. Figure 3C is a diagram showing an example of measurement positions of roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces constituting part of the block-facing end faces 111m-111p of block 110e.
　ここで、鋼板の主磁束方向（または圧延方向）および積層方向に垂直な方向を、必要に応じて幅方向と称する。面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線は、（１）式の算出対象の一対のブロック対向端面の一部を構成する端面を有する鋼板の板面において、当該鋼板の幅方向の中央の位置を通り、且つ、当該鋼板の主磁束方向（または圧延方向）に沿って延びる仮想直線上で測定される。 Here, the direction perpendicular to the main magnetic flux direction (or rolling direction) and lamination direction of the steel plate is referred to as the width direction as necessary. The roughness curve for calculating the in-plane surface roughness Ra(S) is measured on a virtual straight line that passes through the center position in the width direction of the steel plate and extends along the main magnetic flux direction (or rolling direction) of the steel plate on the plate surface having end faces that form part of the opposing end faces of the pair of blocks to be calculated using formula (1).
　図１に示す例では、ブロック対向端面１１１ａ～１１１ｐの一部を構成する端面を有する鋼板の積層方向はｚ軸方向である。また、ブロック対向端面１１１ａ～１１１ｄ、１１１ｅ～１１１ｈの一部を構成する鋼板の主磁束方向（または圧延方向）はｙ軸方向（図１に示す両矢印線の方向）である。また、ブロック対向端面１１１ａ～１１１ｄ、１１１ｅ～１１１ｈの一部を構成する鋼板の幅方向はｘ軸方向である。ブロック対向端面１１１ｉ～１１１ｊ、１１１ｋ～１１１ｌ、１１１ｍ～１１１ｐの一部を構成する鋼板の主磁束方向（または圧延方向）はｘ軸方向（図１に示す両矢印線の方向）である。また、ブロック対向端面１１１ｉ～１１１ｊ、１１１ｋ～１１１ｌ、１１１ｍ～１１１ｐの一部を構成する鋼板の幅方向はｙ軸方向である。 In the example shown in FIG. 1, the lamination direction of the steel plates having end faces that constitute part of the block-facing end faces 111a to 111p is the z-axis direction. The main magnetic flux direction (or rolling direction) of the steel plates that constitute part of the block-facing end faces 111a to 111d, 111e to 111h is the y-axis direction (the direction of the double-headed arrow in FIG. 1). The width direction of the steel plates that constitute part of the block-facing end faces 111a to 111d, 111e to 111h is the x-axis direction. The main magnetic flux direction (or rolling direction) of the steel plates that constitute part of the block-facing end faces 111i to 111j, 111k to 111l, 111m to 111p is the x-axis direction (the direction of the double-headed arrow in FIG. 1). The width direction of the steel plates that constitute part of the block-facing end faces 111i to 111j, 111k to 111l, 111m to 111p is the y-axis direction.
　この場合、図３Ａにおいて、ブロック対向端面１１１ａ～１１１ｄの一部を構成する端面を有する鋼板の幅方向（ｘ軸方向）の中央の位置を通り、且つ、当該鋼板の主磁束方向（または圧延方向、ｙ軸方向）に沿って延びる仮想直線は、仮想直線３０１ａである。同様に、図３Ｄにおいて、ブロック対向端面１１１ｅ～１１１ｈの一部を構成する端面を有する鋼板の幅方向（ｘ軸方向）の中央の位置を通り、且つ、当該鋼板の主磁束方向（または圧延方向、ｙ軸方向）に沿って延びる仮想直線は、仮想直線３０１ｄである。 In this case, in Figure 3A, the imaginary line that passes through the center in the width direction (x-axis direction) of a steel plate having end faces that form part of the block-facing end faces 111a to 111d and extends along the main magnetic flux direction (or rolling direction, y-axis direction) of the steel plate is imaginary line 301a. Similarly, in Figure 3D, the imaginary line that passes through the center in the width direction (x-axis direction) of a steel plate having end faces that form part of the block-facing end faces 111e to 111h and extends along the main magnetic flux direction (or rolling direction, y-axis direction) of the steel plate is imaginary line 301d.
　また、図３Ｂにおいて、ブロック対向端面１１１ｉ～１１１ｊの一部を構成する端面を有する鋼板の幅方向（ｙ軸方向）の中央の位置を通り、且つ、当該鋼板の主磁束方向（または圧延方向、ｘ軸方向）に沿って延びる仮想直線は、仮想直線３０１ｂである。同様に、図３Ｅにおいて、ブロック対向端面１１１ｋ～１１１ｌの一部を構成する端面を有する鋼板の幅方向（ｙ軸方向）の中央の位置を通り、且つ、当該鋼板の主磁束方向（または圧延方向、ｘ軸方向）に沿って延びる仮想直線は、仮想直線３０１ｅである。 In addition, in Figure 3B, the imaginary line that passes through the center in the width direction (y-axis direction) of a steel plate having an end face that constitutes part of the block-facing end faces 111i to 111j and extends along the main magnetic flux direction (or rolling direction, x-axis direction) of the steel plate is imaginary line 301b. Similarly, in Figure 3E, the imaginary line that passes through the center in the width direction (y-axis direction) of a steel plate having an end face that constitutes part of the block-facing end faces 111k to 111l and extends along the main magnetic flux direction (or rolling direction, x-axis direction) of the steel plate is imaginary line 301e.
　また、図３Ｃにおいて、ブロック対向端面１１１ｍ～１１１ｐの一部を構成する端面を有する鋼板の幅方向（ｙ軸方向）の中央の位置を通り、且つ、当該鋼板の主磁束方向（または圧延方向、ｘ軸方向）に沿って延びる仮想直線は、仮想直線３０１ｃである。 In addition, in FIG. 3C, the imaginary line that passes through the center position in the width direction (y-axis direction) of the steel plate having an end face that constitutes part of the block-facing end faces 111m to 111p and extends along the main magnetic flux direction (or rolling direction, x-axis direction) of the steel plate is imaginary line 301c.
　したがって、図３Ａ、図３Ｄに示すように、ブロック対向端面１１１ａ～１１１ｄ、１１１ｅ～１１１ｈの一部を構成する端面を有する鋼板の面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線は、それぞれ、仮想直線３０１ａ、３０１ｄ上で測定される。また、図３Ｂ、図３Ｅに示すように、ブロック対向端面１１１ｉ～１１１ｊ、１１１ｋ～１１１ｌの一部を構成する端面を有する鋼板の面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線は、それぞれ、仮想直線３０１ｂ、３０１ｅ上で測定される。また、図３Ｃに示すように、ブロック対向端面１１１ｍ～１１１ｐの一部を構成する端面を有する鋼板の面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線は、仮想直線３０１ｃ上で測定される。 Therefore, as shown in Figures 3A and 3D, the roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces that constitute part of the block-facing end faces 111a-111d and 111e-111h are measured on the imaginary straight lines 301a and 301d, respectively. As shown in Figures 3B and 3E, the roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces that constitute part of the block-facing end faces 111i-111j and 111k-111l are measured on the imaginary straight lines 301b and 301e, respectively. As shown in Figure 3C, the roughness curves for calculating the in-plane surface roughness Ra(S) of a steel plate having end faces that constitute part of the block-facing end faces 111m-111p are measured on the imaginary straight line 301c.
　なお、前述したようにして面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線の測定位置（仮想直線）を定める際に、鋼板の形状によって当該仮想直線が複数に分離される場合がある。この場合、当該分離された複数の仮想直線のうちのいずれか一つの仮想直線上で粗さ曲線を測定する。また、当該複数の仮想直線が分離されていないものとして（すなわち、当該複数の仮想直線の間隔を０（零）として）、当該複数の仮想直線で粗さ曲線を測定しても良い。 When determining the measurement position (virtual line) of the roughness curve for calculating the in-plane surface roughness Ra(S) as described above, the virtual line may be separated into multiple lines depending on the shape of the steel plate. In this case, the roughness curve is measured on any one of the multiple separated virtual lines. Alternatively, the roughness curve may be measured on the multiple virtual lines as if the multiple virtual lines were not separated (i.e., the distance between the multiple virtual lines is set to 0 (zero)).
　以下の説明では、面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線（粗さ曲線要素）が測定される仮想直線３０１ａ～３０１ｅの位置を、必要に応じて面内方向測定位置と称する。 In the following description, the positions of the virtual straight lines 301a to 301e where the roughness curve (roughness curve elements) for calculating the in-plane surface roughness Ra(S) are measured will be referred to as in-plane measurement positions as necessary.
　（１）式の算出対象の一対のブロック対向端面の一方のブロック対向端面を構成する複数の鋼板を一枚ずつ抜き取り、抜き取った鋼板の面内方向測定位置において面内方向表面粗さＲａ（Ｓ）を測定する。このようにすることに代えて、当該一方のブロック対向端面を有するブロックを構成するために用いる積層前の鋼板の面内方向測定位置において面内方向表面粗さＲａ（Ｓ）を測定しても良い。このような測定を当該一方のブロック対向端面を構成する全ての鋼板のそれぞれについて行う。例えば、積層枚数が２００枚である場合、一つのブロック対向端面について２００個の面内方向表面粗さＲａ（Ｓ）が測定される。以上のようにして測定された複数（前述の例では２００個）の面内方向表面粗さＲａ（Ｓ）の代表値を、当該一方のブロック対向端面の面内方向表面粗さＲａ（Ｓ）とする。代表値は、例えば、算術平均値である。算術平均値に代えて中央値等を用いても良い。（１）式の算出対象の一対のブロック対向端面の他方のブロック対向端面の面内方向表面粗さＲａ（Ｓ）も、一方のブロック対向端面の面内方向表面粗さＲａ（Ｓ）と同様にして算出する。 　The multiple steel plates constituting one of the pair of block opposing end faces to be calculated using formula (1) are extracted one by one, and the in-plane surface roughness Ra(S) of the extracted steel plate is measured at the in-plane measurement position. Alternatively, the in-plane surface roughness Ra(S) of the steel plate before lamination used to construct the block having the one of the block opposing end faces may be measured at the in-plane measurement position. Such measurements are performed for each of all steel plates constituting the one of the block opposing end faces. For example, if the number of stacked sheets is 200, 200 in-plane surface roughnesses Ra(S) are measured for one of the block opposing end faces. The representative value of the multiple in-plane surface roughnesses Ra(S) measured in this manner (200 in the above example) is taken as the in-plane surface roughness Ra(S) of the one of the block opposing end faces. The representative value is, for example, the arithmetic mean value. Instead of the arithmetic mean value, a median value or the like may be used. The in-plane surface roughness Ra(S) of the other of the pair of opposing block end faces that are the subject of calculation of equation (1) is calculated in the same manner as the in-plane surface roughness Ra(S) of one of the opposing block end faces.
　以上のようにして一対のブロック対向端面の一方および他方のブロック対向端面の面内方向表面粗さＲａ（Ｓ）を算出することを、一対のブロック対向端面１１１ａおよび１１１ｉ、１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐのそれぞれについて行う。 The in-plane surface roughness Ra(S) of one and the other of a pair of opposing block end faces is calculated in the above manner for each of the pairs of opposing block end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.
　前述したように、積層方向表面粗さＲａ（Ｄ）および面内方向表面粗さＲａ（Ｓ）を算出するために、例えば、粗さ曲線（粗さ曲線要素）が測定される。粗さ曲線（粗さ曲線要素）の測定は、例えば、一つのブロック対向端面を構成する複数の鋼板のそれぞれについて行われる。また、粗さ曲線（粗さ曲線要素）の測定は、積層方向測定位置および面内方向測定位置のそれぞれにおいて行われる。 As described above, to calculate the stacking direction surface roughness Ra(D) and the in-plane direction surface roughness Ra(S), for example, a roughness curve (roughness curve element) is measured. The roughness curve (roughness curve element) is measured, for example, for each of the multiple steel plates that make up the opposing end face of one block. In addition, the roughness curve (roughness curve element) is measured at each of the stacking direction measurement position and the in-plane direction measurement position.
　例えば、積層枚数が２００枚である場合、一つのブロック対向端面について、積層方向表面粗さＲａ（Ｄ）を算出するための粗さ曲線（粗さ曲線要素）として、２００個の粗さ曲線（粗さ曲線要素）が測定される。以上のようにして測定された複数（前述の例では２００個）の粗さ曲線の代表値を、当該一つのブロック対向端面の積層方向表面粗さＲａ（Ｄ）を算出するための粗さ曲線とする。なお、複数（前述の例では２００個）の粗さ曲線の代表値は、当該複数の粗さ曲線のそれぞれにおいて、板厚方向の位置が同じ点での値の代表値を算出することにより算出される。代表値は、例えば、算術平均値である。算術平均値に代えて中央値等を用いても良い。また、複数の鋼板の板厚が異なる場合、例えば、複数（前述の例では２００個）の粗さ曲線を繋ぎ合わせた粗さ曲線を積層方向表面粗さＲａ（Ｄ）を算出するための粗さ曲線（粗さ曲線要素）としても良い。 For example, when the number of laminated sheets is 200, 200 roughness curves (roughness curve elements) are measured for one block-facing end face as a roughness curve (roughness curve element) for calculating the laminate direction surface roughness Ra (D). The representative value of the multiple roughness curves (200 in the above example) measured in the above manner is used as the roughness curve for calculating the laminate direction surface roughness Ra (D) of the one block-facing end face. The representative value of the multiple roughness curves (200 in the above example) is calculated by calculating the representative value of the values at the same position in the plate thickness direction in each of the multiple roughness curves. The representative value is, for example, the arithmetic mean value. Instead of the arithmetic mean value, a median value or the like may be used. In addition, when the plate thicknesses of multiple steel plates are different, for example, a roughness curve obtained by joining multiple roughness curves (200 in the above example) may be used as the roughness curve (roughness curve element) for calculating the laminate direction surface roughness Ra (D).
　面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線は、例えば、一つのブロック対向端面の一部を構成する端面を有する全ての鋼板のそれぞれについて測定される。例えば、積層枚数が２００枚である場合、一つのブロック対向端面について、面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線として、２００個の粗さ曲線が測定される。以上のようにして測定された複数（前述の例では２００個）の粗さ曲線の代表値を、当該ブロック対向端面の一部を構成する端面を有する鋼板の面内方向表面粗さＲａ（Ｓ）を算出するための粗さ曲線とする。複数の粗さ曲線の代表値は、例えば、板面方向の位置（ｘ座標およびｙ座標）が同じ位置での値の算出平均値を算出することにより得られる。代表値は、例えば、算術平均値である。算術平均値に代えて中央値等を用いても良い。 The roughness curves for calculating the in-plane surface roughness Ra(S) are measured for all steel plates having end faces that constitute a part of one block facing end face, for example. For example, if the number of laminated sheets is 200, 200 roughness curves are measured for one block facing end face as roughness curves for calculating the in-plane surface roughness Ra(S). The representative value of the multiple roughness curves (200 in the above example) measured in this manner is used as the roughness curve for calculating the in-plane surface roughness Ra(S) of the steel plate having an end face that constitutes a part of the block facing end face. The representative value of the multiple roughness curves can be obtained, for example, by calculating the calculated average value of values at the same position (x coordinate and y coordinate) in the plate surface direction. The representative value is, for example, the arithmetic mean value. The median value or the like may be used instead of the arithmetic mean value.
　粗さ曲線（粗さ曲線要素）の測定には、例えば、株式会社キーエンス製のワンショット3D形状測定機（型式名；VR-6000）を使用しても良い。測定視野については、例えば、１視野の広さが５００μｍ×５００μｍとなるように例えば測定倍率を２００倍に設定する。デジタルマイクロスコープで粗さ曲線要素の平均高さを測定する場合、カットオフ値λｓ＝０μｍおよびカットオフ値λｃ＝０ｍｍとすることにより、測定時の鋼板の振動を補正しても良い。測定倍率は、１００倍以上が好ましく、より好ましくは５００倍～７００倍である。 For measuring the roughness curve (roughness curve element), for example, a one-shot 3D shape measuring instrument (model name: VR-6000) manufactured by Keyence Corporation may be used. For the measurement field of view, for example, the measurement magnification is set to 200 times so that the width of one field of view is 500 μm × 500 μm. When measuring the average height of the roughness curve element with a digital microscope, the vibration of the steel plate during measurement may be corrected by setting the cutoff value λs = 0 μm and the cutoff value λc = 0 mm. The measurement magnification is preferably 100 times or more, and more preferably 500 times to 700 times.
　同一のブロック対向端面について算出した面内方向表面粗さＲａ（Ｓ）および積層方向表面粗さＲａ（Ｄ）を用いて、Ｒａ（Ｄ）／Ｒａ（Ｓ）を算出する。そして、算出したＲａ（Ｄ）／Ｒａ（Ｓ）が（１）式を満たすか否かを確認する。
　（１）式を満たすようにするための手法は、鋼板の端面の粗さを調整することができる手法であれば良い。鋼板の端面の粗さは、例えば、研削、切削、および研磨のうちのいずれか一つにより調整される。 Using the in-plane surface roughness Ra(S) and the stacking direction surface roughness Ra(D) calculated for the same block facing end face, Ra(D)/Ra(S) is calculated, and it is confirmed whether the calculated Ra(D)/Ra(S) satisfies formula (1).
The method for satisfying formula (1) may be any method capable of adjusting the roughness of the end surface of the steel sheet. The roughness of the end surface of the steel sheet is adjusted by, for example, any one of grinding, cutting, and polishing.
　例えば、ブロック１１０ａ～１１０ｅの平面形状（図１に示すｘ－ｙ面の形状）を得るために鋼板を切断する際に、一枚一枚の鋼板の端面の粗さを調整しても良い。また、ブロック１１０ａ～１１０ｅの平面形状に切断された鋼板の一枚一枚の鋼板の端面の粗さを調整しても良い。例えば、一枚一枚の鋼板をせん断する場合、せん断機の上下の刃のクリアランスを制御することにより、一枚一枚の鋼板の端面の粗さを調整しても良い。また、複数の鋼板を積み重ねた後に、ブロック対向端面１１１ａ～１１１ｐに対応する端面の粗さを調整しても良い。また、これらのいずれか二つ以上を組み合わせても良い。 For example, when cutting the steel plates to obtain the planar shapes of the blocks 110a to 110e (the shapes of the x-y planes shown in FIG. 1), the roughness of the end faces of each steel plate may be adjusted. Also, the roughness of the end faces of each steel plate cut into the planar shapes of the blocks 110a to 110e may be adjusted. For example, when shearing each steel plate, the roughness of the end faces of each steel plate may be adjusted by controlling the clearance between the upper and lower blades of the shearing machine. Also, after stacking multiple steel plates, the roughness of the end faces corresponding to the block-facing end faces 111a to 111p may be adjusted. Also, any two or more of these may be combined.
　そして、複数の鋼板を積み重ねた後に、ブロック対向端面１１１ａ～１１１ｐに対応する端面について（１）式を満たすか否かを確認しても良い。そして、（１）式を満たしていない場合には、当該端面の粗さを再調整しても良い。また、積み重ねた複数の鋼板をばらした後、一枚一枚の鋼板の端面の粗さを再調整しても良い。また、複数の鋼板を積み重ねる前に鋼板の端面の粗さの調整を行わずに、複数の鋼板を積み重ねた後に、ブロック対向端面１１１ａ～１１１ｐに対応する端面について（１）式を満たすか否かを確認しても良い。そして、（１）式を満たさない場合には、（１）式を満たすように、当該端面の粗さを調整しても良い。 Then, after stacking the multiple steel plates, it may be confirmed whether the end faces corresponding to the block-facing end faces 111a to 111p satisfy formula (1). If formula (1) is not satisfied, the roughness of the end faces may be readjusted. Also, after disassembling the stacked multiple steel plates, the roughness of the end face of each steel plate may be readjusted. Also, without adjusting the roughness of the end faces of the steel plates before stacking the multiple steel plates, it may be confirmed whether the end faces corresponding to the block-facing end faces 111a to 111p satisfy formula (1) after stacking the multiple steel plates. If formula (1) is not satisfied, the roughness of the end faces may be adjusted so that formula (1) is satisfied.
　（１）式を満たすことにより、積鉄心１００の励磁時に、積層方向（ｚ軸方向）で隣接する鋼板が、ブロック対向端面１１１ａ～１１１ｐにおいて、相互に引き付け合うように作用する結合力を、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）およびその付近の領域に付与することができると考えられる。（１）式において、Ｒａ（Ｄ）／Ｒａ（Ｓ）が１を下回ると（Ｒａ（Ｄ）／Ｒａ（Ｓ）＜１）、ブロック対向端面１１１ａ～１１１ｐの粗さが小さくなりすぎる（平らな状態に近くなる）。したがって、前述した結合力を、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）およびその付近の領域に付与することができないと考えられる。一方、Ｒａ（Ｄ）／Ｒａ（Ｓ）が１２を上回ると（Ｒａ（Ｄ）／Ｒａ（Ｓ）＞１２）、前述した結合力が強くなりすぎるために鋼板に過剰な圧縮応力が導入され、この圧縮応力によって、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）が振動すると考えられる。 By satisfying formula (1), when stacked core 100 is excited, it is believed that a bonding force that acts to attract each other at block opposing end faces 111a to 111p between adjacent steel plates in the stacking direction (z-axis direction) can be applied to the butt portions (block opposing end faces 111a to 111p) of blocks 110a to 110e and the areas nearby. In formula (1), if Ra(D)/Ra(S) is below 1 (Ra(D)/Ra(S)<1), the roughness of block opposing end faces 111a to 111p becomes too small (becoming close to a flat state). Therefore, it is believed that the aforementioned bonding force cannot be applied to the butt portions (block opposing end faces 111a to 111p) of blocks 110a to 110e and the areas nearby. On the other hand, if Ra(D)/Ra(S) exceeds 12 (Ra(D)/Ra(S)>12), the aforementioned bonding force becomes too strong, and excessive compressive stress is introduced into the steel plate, and this compressive stress is thought to cause the butt joints of blocks 110a-110e (block-facing end faces 111a-111p) to vibrate.
　また、本発明者らは、積鉄心１００の騒音の抑制効果をより確実に高める観点から、（１）式に代えて以下の（２）式を用いるのがより好ましいという知見を得た。
　６≦Ｒａ（Ｄ）／Ｒａ（Ｓ）≦８　・・・（２） Furthermore, the inventors have found that, from the viewpoint of more reliably increasing the noise suppression effect of the stacked core 100, it is more preferable to use the following formula (2) instead of formula (1).
6≦Ra(D)/Ra(S)≦8 ... (2)
　前述したように、少なくとも一つの一対のブロック対向端面１１１ａおよび１１１ｉ、１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐのそれぞれにおいて（１）式（好ましくはさらに（２）式）を満たせば良い。しかしながら、これらの一対のブロック対向端面のうちの２以上の一対のブロック対向端面のそれぞれにおいて（１）式（好ましくはさらに（２）式）を満たすのが好ましい。また、これらの一対のブロック対向端面の総数（図１に示す例では８）の１／２倍以上の一対のブロック対向端面のそれぞれにおいて（１）式（好ましくはさらに（２）式）を満たすのがより好ましい。また、全ての一対のブロック対向端面のそれぞれにおいて（１）式（好ましくはさらに（２）式）を満たすのがより一層好ましい。 As described above, it is sufficient that at least one pair of block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p satisfy formula (1) (preferably also formula (2)). However, it is preferable that at least two pairs of block opposing end faces among these pairs of block opposing end faces satisfy formula (1) (preferably also formula (2)). It is more preferable that at least half the total number of pairs of block opposing end faces (8 in the example shown in FIG. 1) satisfy formula (1) (preferably also formula (2)). It is even more preferable that all pairs of block opposing end faces satisfy formula (1) (preferably also formula (2)).
　また、本発明者らは、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面）での振動を、鋼板とは別の材料を用いずに抑制するために、鋼板の結晶粒に着目した。ここで、ブロック対向端面１１１ａ～１１１ｐの一部を構成する端面を有する鋼板の当該端面を、必要に応じて鋼板対向端面と称する。また、鋼板対向端面を有する鋼板に存在する結晶粒のうち、当該鋼板対向端面を境界として含む結晶粒の数を、必要に応じて、鋼板対向端面上の結晶粒の数と称する。また、鋼板対向端面上の結晶粒の数を、当該鋼板対向端面の長さで除した値を、必要に応じて、鋼板対向端面上の単位長さ当たりの結晶粒の数と称する。ここで、鋼板対向端面上の結晶粒の数をｎ（個）とする。また、当該鋼板対向端面の長さをＬ（ｍｍ）とする。そうすると、鋼板対向端面上の単位長さ当たりの結晶粒の数はｎ／Ｌ（個／ｍｍ）となる。 The inventors also focused on the crystal grains of the steel plate in order to suppress vibrations at the butt joints (block-facing end faces) of the blocks 110a to 110e without using a material other than the steel plate. Here, the end faces of the steel plate having end faces constituting part of the block-facing end faces 111a to 111p are referred to as the steel plate-facing end faces as necessary. Furthermore, the number of crystal grains present in the steel plate having the steel plate-facing end face that includes the steel plate-facing end face as a boundary is referred to as the number of crystal grains on the steel plate-facing end face as necessary. Furthermore, the value obtained by dividing the number of crystal grains on the steel plate-facing end face by the length of the steel plate-facing end face is referred to as the number of crystal grains per unit length on the steel plate-facing end face as necessary. Here, the number of crystal grains on the steel plate-facing end face is n (pieces). Furthermore, the length of the steel plate-facing end face is L (mm). Then, the number of crystal grains per unit length on the steel plate-facing end face is n/L (pieces/mm).
　本発明者らは、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌと、積鉄心１００の騒音レベルと、の関係を調査した。その際、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌを、以下のようにして算出した。まず、一対のブロック対向端面１１１ａおよび１１１ｉ、１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐのうち、一方のブロック対向端面の一部を構成する端面を有する全ての鋼板のそれぞれについて、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌを算出した。そして、算出した鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌの算術平均値を、当該一方のブロック対向端面における鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌとして算出した。このようにして鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌを算出した結果、本発明者らは、鋼板対向端面上の単位長さ当たりの数ｎ／Ｌが０．５（個／ｍｍ）であるときを境にして、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）の振動によって積鉄心１００の騒音レベルが顕著に変化するという知見を得た。鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌが０．５（個／ｍｍ）を上回ると、鋼板対向端面において、多くの結晶粒がそれぞれ振動するために、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）の振動を十分に低減することができないと考えられる。 The inventors investigated the relationship between the number of crystal grains per unit length n/L on the steel plate facing end face and the noise level of the stacked core 100. In this case, the number of crystal grains per unit length n/L on the steel plate facing end face was calculated as follows. First, the number of crystal grains per unit length n/L on the steel plate facing end face was calculated for all steel plates having an end face constituting a part of one of the pair of block facing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p. Then, the arithmetic mean value of the number of crystal grains per unit length n/L on the calculated steel plate facing end face was calculated as the number of crystal grains per unit length n/L on the steel plate facing end face at the one of the block facing end faces. As a result of calculating the number n/L of crystal grains per unit length on the steel plate facing end face in this manner, the inventors have found that the noise level of the stacked core 100 changes significantly due to the vibration of the butt joints of the blocks 110a to 110e (block facing end faces 111a to 111p) when the number n/L per unit length on the steel plate facing end face is 0.5 (pieces/mm). When the number n/L of crystal grains per unit length on the steel plate facing end face exceeds 0.5 (pieces/mm), many crystal grains vibrate on the steel plate facing end face, so it is thought that the vibration of the butt joints of the blocks 110a to 110e (block facing end faces 111a to 111p) cannot be sufficiently reduced.
　このことから、本発明者らは、一対のブロック対向端面１１１ａおよび１１１ｉ、１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐのうち少なくとも一方のブロック対向端面（好ましくは両方のブロック対向端面）において、以下の（３）式を満たすことにより、積鉄心１００の振動を抑制することができるという知見を得た。
　ｎ／Ｌ≦０．５　・・・（３） From this, the inventors have discovered that vibration of the stacked core 100 can be suppressed by satisfying the following formula (3) in at least one of the pair of block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, or 111h and 111p (preferably both of the block opposing end faces).
n / L ≦ 0.5 ... (3)
　図４Ａ～図４Ｄは、鋼板対向端面上の結晶粒の数ｎおよび鋼板対向端面の長さＬの一例を説明する図である。 Figures 4A to 4D are diagrams illustrating an example of the number n of crystal grains on the opposing end faces of the steel plate and the length L of the opposing end faces of the steel plate.
　図４Ａ、図４Ｄは、ブロック１１０ａ、１１０ｂが有するブロック対向端面１１１ａ～１１１ｄ、１１１ｅ～１１１ｈの一部を構成する鋼板対向端面上の結晶粒の数ｎおよび鋼板対向端面の長さＬを説明する図である。図４Ｂ、図４Ｅは、ブロック１１０ｃ、１１０ｄが有するブロック対向端面１１１ｉ～１１１ｊ、１１１ｋ～１１１ｌの一部を構成する鋼板対向端面上の結晶粒の数ｎおよび鋼板対向端面の長さＬを説明する図である。図４Ｃは、ブロック１１０ｅが有するブロック対向端面１１１ｍ～１１１ｐの一部を構成する鋼板対向端面上の結晶粒の数ｎおよび鋼板対向端面の長さＬを説明する図である。 FIGS. 4A and 4D are diagrams for explaining the number n of crystal grains on the steel plate facing end faces constituting part of the block facing end faces 111a-111d, 111e-111h of blocks 110a and 110b, and the length L of the steel plate facing end faces. FIGS. 4B and 4E are diagrams for explaining the number n of crystal grains on the steel plate facing end faces constituting part of the block facing end faces 111i-111j, 111k-111l of blocks 110c and 110d, and the length L of the steel plate facing end faces. FIG. 4C is a diagram for explaining the number n of crystal grains on the steel plate facing end faces constituting part of the block facing end faces 111m-111p of block 110e, and the length L of the steel plate facing end faces.
　図４Ａでは、ブロック対向端面１１１ａの一部を構成する鋼板対向端面を有する鋼板のうちの一枚の鋼板に存在する結晶粒のうち、当該鋼板対向端面を境界として含む結晶粒として、五つの結晶粒からなる結晶粒群４０１ａを例示する。この場合、ブロック対向端面１１１ａの一部を構成する鋼板対向端面上の結晶粒の数ｎは５になる。図１および図２Ａに示すように、ブロック対向端面１１１ａの一部を構成する鋼板対向端面を有する鋼板は、積層方向（ｚ軸方向）において複数ある。したがって、これら複数の鋼板のそれぞれについて、ブロック対向端面１１１ａの一部を構成する鋼板対向端面上の結晶粒の数ｎを計数する。例えば、ブロック１１０ａが１００枚の鋼板を有する場合であって、ブロック対向端面１１１ａの一部を構成する当該１００枚の鋼板の鋼板対向端面上の結晶粒の数ｎが全て５である場合、ブロック対向端面１１１ａの一部を構成する鋼板対向端面上の結晶粒の数ｎの合計値は５００（＝１００×５）になる。 In Figure 4A, a crystal grain group 401a consisting of five crystal grains is shown as an example of crystal grains that include the steel plate facing end face as a boundary among the crystal grains present in one of the steel plates having a steel plate facing end face that constitutes part of the block facing end face 111a. In this case, the number n of crystal grains on the steel plate facing end face that constitutes part of the block facing end face 111a is 5. As shown in Figures 1 and 2A, there are multiple steel plates in the stacking direction (z-axis direction) that have a steel plate facing end face that constitutes part of the block facing end face 111a. Therefore, for each of these multiple steel plates, the number n of crystal grains on the steel plate facing end face that constitutes part of the block facing end face 111a is counted. For example, if block 110a has 100 steel plates, and the number n of crystal grains on the steel plate facing end faces of the 100 steel plates that make up part of block facing end face 111a is all 5, the total number n of crystal grains on the steel plate facing end faces that make up part of block facing end face 111a is 500 (= 100 x 5).
　ブロック対向端面１１１ａ以外のブロック対向端面１１１ｂ～１１１ｐの一部を構成する鋼板対向端面上の結晶粒の数ｎも同様にして計数される。図４Ａ～図４Ｅでは、ブロック対向端面１１１ｂ、１１１ｃ、１１１ｄ、１１１ｉ、１１１ｊ、１１１ｍ、１１１ｎ、１１１ｏ、１１１ｐ、１１１ｅ、１１１ｆ、１１１ｇ、１１１ｈ、１１１ｋ、１１１ｌの一部を構成する鋼板対向端面を有する鋼板のうちの一枚の鋼板に存在する結晶粒のうち、当該鋼板対向端面を境界として含む結晶粒群として、それぞれ、四つ、三つ、五つ、七つ、六つ、五つ、四つ、四つ、三つ、五つ、四つ、三つ、五つ、七つ、六つの結晶粒からなる結晶粒群４０１ｂ、４０１ｃ、４０１ｄ、４０１ｅ、４０１ｆ、４０１ｇ、４０１ｈ、４０１ｉ、４０１ｊ、４０１ｋ、４０１ｌ、４０１ｍ、４０１ｎ、４０１ｏ、４０１ｐを示す。 The number n of crystal grains on the steel plate facing end faces that constitute part of the block facing end faces 111b to 111p other than the block facing end face 111a is also counted in the same manner. 4A to 4E show crystal grain groups 401b, 401c, 401d, 401e, 401f, 401g, 401h, 401i, 401j, 111m, 111n, 111o, 111p, 111e, 111f, 111g, 111h, 111k, and 111l, which are crystal grain groups that include the steel plate facing end face as a boundary, and are made up of four, three, five, seven, six, five, four, four, three, five, four, three, five, seven, and six crystal grains, respectively, among the crystal grains present in one steel plate among the steel plates having the steel plate facing end face that constitutes a part of the block facing end faces 111b, 111c, 111d, 111i, 111j, 111m, 111n, 111o, 111p, 111e, 111f, 111g, 111h, 111k, and 111l.
　鋼板対向端面上の結晶粒の数ｎを計数する手法は、結晶粒の数を測定することができる手法であれば良い。例えば、以下のようにして電子顕微鏡または光学顕微鏡による観察を行うことで鋼板対向端面上の結晶粒の数ｎを計数しても良い。まず、鋼板対向端面（切断面）を５％ナイタール溶液で１００秒間～３００秒間、腐食した後、光学顕微鏡で結晶粒界を観察する。光学顕微鏡として、例えば、オリンパス株式会社製の工業用顕微鏡 BX53Mを使用しても良い。鋼板対向端面（切断面）を、当該鋼板対向端面の長手方向の全長にわたって観察した際に、一方の板面から他方の板面（例えば板厚方向）に延びる曲線や直線を一律に結晶粒界として定義する。一つの鋼板対向端面（切断面）において、このようにして定義される結晶粒界の数がｑ個ある場合、ｑ＋１が当該鋼板対向端面上の結晶粒の数ｎ（ｎ＝ｑ＋１）になる（ｑは非負整数である）。例えば、一つの鋼板対向端面（切断面）において、このようにして定義される結晶粒界の数が３である場合、当該鋼板対向端面上の結晶粒の数ｎは４である。仮に一つの鋼板対向端面における結晶粒界の数が０（零）である場合、当該鋼板対向端面上の結晶粒の数ｎは１（＝０＋１）となる。 The method for counting the number n of crystal grains on the opposing end surface of the steel plate may be any method capable of measuring the number of crystal grains. For example, the number n of crystal grains on the opposing end surface of the steel plate may be counted by observing with an electron microscope or an optical microscope as follows. First, the opposing end surface (cut surface) of the steel plate is corroded with a 5% nital solution for 100 to 300 seconds, and then the grain boundaries are observed with an optical microscope. As the optical microscope, for example, an industrial microscope BX53M manufactured by Olympus Corporation may be used. When the opposing end surface (cut surface) of the steel plate is observed over the entire longitudinal length of the opposing end surface of the steel plate, curves and straight lines extending from one plate surface to the other plate surface (for example, in the plate thickness direction) are uniformly defined as grain boundaries. When the number of grain boundaries defined in this way is q on one opposing end surface (cut surface) of the steel plate, q+1 is the number n of crystal grains on the opposing end surface of the steel plate (n=q+1) (q is a non-negative integer). For example, if the number of grain boundaries defined in this way on one steel plate facing end surface (cut surface) is 3, the number of grains n on that steel plate facing end surface is 4. If the number of grain boundaries on one steel plate facing end surface is 0 (zero), the number of grains n on that steel plate facing end surface is 1 (= 0 + 1).
　また、図４Ａ～図４Ｅにおいて、鋼板対向端面の長さＬは、当該鋼板対向端面を有する鋼板を、当該鋼板の板面に垂直な方向（図４Ａ～図４Ｅの紙面に垂直な方向）から見た場合に見える当該鋼板対向端面の長さである。図４Ａには、ブロック対向端面１１１ａの一部を構成する鋼板対向端面の長さＬが長さＬ１であることを示す。図１および図２Ａに示すように、ブロック対向端面１１１ａの一部を構成する鋼板対向端面を有する鋼板は、積層方向（ｚ軸方向）において複数ある。したがって、これら複数の鋼板のそれぞれについて、ブロック対向端面１１１ａの一部を構成する鋼板対向端面の長さＬを測定する。 In addition, in Figures 4A to 4E, the length L of the steel plate facing end face is the length of the steel plate facing end face as seen when the steel plate having the steel plate facing end face is viewed in a direction perpendicular to the plate surface of the steel plate (perpendicular to the paper surface of Figures 4A to 4E). Figure 4A shows that the length L of the steel plate facing end face constituting part of the block facing end face 111a is length L1. As shown in Figures 1 and 2A, there are multiple steel plates in the stacking direction (z-axis direction) that have steel plate facing end faces constituting part of the block facing end face 111a. Therefore, for each of these multiple steel plates, the length L of the steel plate facing end face constituting part of the block facing end face 111a is measured.
　ブロック対向端面１１１ａ以外のブロック対向端面１１１ｂ～１１１ｐの一部を構成する鋼板対向端面の長さＬも同様にして測定される。図４Ａ～図４Ｅでは、ブロック対向端面１１１ｂ、１１１ｃ、１１１ｄ、１１１ｉ、１１１ｊ、１１１ｍ、１１１ｎ、１１１ｏ、１１１ｐ、１１１ｅ、１１１ｆ、１１１ｇ、１１１ｈ、１１１ｋ、１１１ｌの一部を構成する鋼板対向端面の長さＬとして、それぞれ、Ｌ２、Ｌ３、Ｌ４、Ｌ５、Ｌ６、Ｌ７、Ｌ８、Ｌ９、Ｌ１０、Ｌ１１、Ｌ１２、Ｌ１３、Ｌ１４、Ｌ１５、Ｌ１６を示す。 The length L of the steel plate facing end faces constituting part of the block facing end faces 111b to 111p other than the block facing end face 111a is measured in the same manner. In Figures 4A to 4E, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11, L12, L13, L14, L15, and L16 are shown as the length L of the steel plate facing end faces constituting part of the block facing end faces 111b, 111c, 111d, 111i, 111j, 111m, 111n, 111o, 111p, 111e, 111f, 111g, 111h, 111k, and 111l, respectively.
　鋼板対向端面の長さＬを測定する手法は、鋼板の端面の長さを測定することができる手法であれば良い。例えば、ノギス等を用いた直接測定により鋼板対向端面の長さＬを測定しても良い。また、画像解析等を用いた間接測定により鋼板対向端面の長さＬを測定しても良い。 The method for measuring the length L of the opposing end faces of the steel plate may be any method capable of measuring the length of the end faces of the steel plate. For example, the length L of the opposing end faces of the steel plate may be measured by direct measurement using a vernier caliper or the like. The length L of the opposing end faces of the steel plate may also be measured by indirect measurement using image analysis or the like.
　なお、例えば、一つのブロック対向端面の一部を構成する鋼板対向端面上の結晶粒の数ｎの代表値（例えば、算術平均値）、当該ブロック対向端面の一部を構成する鋼板対向端面の長さＬの代表値（例えば、算術平均値）を、それぞれ（３）式のｎ、Ｌとして用いることにより、（３）式を満たすか否かを確認してもよい。また、（３）式を満たすか否かの確認は、一つの鋼板対向端面ごとに行われても良い。 It is also possible to confirm whether formula (3) is satisfied by using, for example, a representative value (e.g., the arithmetic mean value) of the number n of crystal grains on a steel plate facing end face that constitutes part of one block facing end face, and a representative value (e.g., the arithmetic mean value) of the length L of the steel plate facing end face that constitutes part of the block facing end face, as n and L in formula (3), respectively. Also, confirmation of whether formula (3) is satisfied may be performed for each steel plate facing end face.
　（３）式を満たすようにするために鋼板の製造時に鋼板の結晶粒の大きさを制御する必要がある。例えば、析出物制御および集合組織制御を行うための窒化焼鈍時の窒化量と、二次再結晶を生じさせる仕上げ焼鈍時の焼鈍温度および保持時間（焼鈍温度と時間との関係）と、のうち少なくとも一方を制御することにより、（３）式を満たすように鋼板の結晶粒の大きさを制御しても良い。具体的に、窒化焼鈍時の雰囲気に供給されるアンモニアの流量を調整することと、仕上げ焼鈍時の均熱時間を調整する（長くする）ことと、仕上げ焼鈍時の均熱温度に達する前に保定の時間を設け当該保定の時間を調整することと、の少なくとも一つを行うことにより、（３）式を満たすように鋼板の結晶粒の大きさを制御しても良い。 In order to satisfy formula (3), it is necessary to control the crystal grain size of the steel sheet during its manufacture. For example, the crystal grain size of the steel sheet may be controlled to satisfy formula (3) by controlling at least one of the amount of nitriding during nitriding annealing for controlling precipitates and texture, and the annealing temperature and holding time (relationship between annealing temperature and time) during finish annealing for causing secondary recrystallization. Specifically, the crystal grain size of the steel sheet may be controlled to satisfy formula (3) by performing at least one of the following: adjusting the flow rate of ammonia supplied to the atmosphere during nitriding annealing, adjusting (lengthening) the soaking time during finish annealing, and providing a holding time before reaching the soaking temperature during finish annealing and adjusting the holding time.
　（１）式（または（２）式）と（３）式とを満たすことにより、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）での振動を抑制することができる。このように、（１）式（または（２）式）と（３）式との双方を満たすようにすることが好ましい。しかしながら、（３）式を満たすためには、鋼板の材質を選択しなければならない。また、（３）式を満たしているか否かの確認作業の負担は、（１）式（または（２）式）を満たしているか否かの確認作業の負担よりも大きい。また、（３）式を満たしていない場合、鋼板の再製造が必要になる。したがって、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）の振動を簡便に抑制する観点から、（１）式（または（２）式）のみを満たすようにしても良い。 By satisfying formula (1) (or formula (2)) and formula (3), vibrations at the butt joints of blocks 110a to 110e (block-facing end faces 111a to 111p) can be suppressed. In this way, it is preferable to satisfy both formula (1) (or formula (2)) and formula (3). However, in order to satisfy formula (3), the material of the steel plate must be selected. Furthermore, the burden of the work of checking whether formula (3) is satisfied is greater than the burden of the work of checking whether formula (1) (or formula (2)) is satisfied. Furthermore, if formula (3) is not satisfied, the steel plate must be remanufactured. Therefore, from the viewpoint of simply suppressing vibrations at the butt joints of blocks 110a to 110e (block-facing end faces 111a to 111p), it is also possible to satisfy only formula (1) (or formula (2)).
　図５は、本実施形態の積鉄心１００の製造方法の一例を示すフローチャートである。
　まず、ステップＳ５０１において、鋼板製造工程が行われる。鋼板製造工程では、積鉄心１００を構成する鋼板を製造する。鋼板の製造方法として、公知の方法を採用しても良い。ただし、本実施形態では、（３）式を満たすように鋼板の結晶粒の大きさを制御する。前述したように、焼鈍条件を制御することにより、鋼板の結晶粒の大きさを制御しても良い。また、ブロック１１０ａ～１１０ｅの突合部（ブロック対向端面１１１ａ～１１１ｐ）の振動を簡便に抑制する観点から、（３）式を満たすか否かを判定しない場合には、（３）式を満たすように鋼板の結晶粒の大きさを制御しなくても良い。 FIG. 5 is a flowchart showing an example of a method for manufacturing the stacked core 100 of this embodiment.
First, in step S501, a steel plate manufacturing process is performed. In the steel plate manufacturing process, steel plates constituting the stacked core 100 are manufactured. A known method may be adopted as a method for manufacturing the steel plates. However, in this embodiment, the crystal grain size of the steel plate is controlled so as to satisfy the formula (3). As described above, the annealing conditions may be controlled to control the crystal grain size of the steel plate. In addition, from the viewpoint of simply suppressing vibrations of the butt portions (block opposing end faces 111a to 111p) of the blocks 110a to 110e, if it is not determined whether or not the formula (3) is satisfied, it is not necessary to control the crystal grain size of the steel plate so as to satisfy the formula (3).
　次に、ステップＳ５０２において、切断工程が行われる。切断工程では、ステップＳ５０１で製造された鋼板を切断する。本実施形態では、ステップＳ５０１で製造された鋼板を、切断後の鋼板の板面の形状が、ブロック１１０ａ～１１０ｅの平面形状（図１に示すｘ－ｙ面の形状）になるように切断する。鋼板の切断方法として、公知の方法を採用しても良い。例えば、鋼板の切断は、打ち抜き加工により行われても良い。また、鋼板の切断は、レーザ加工により行われても良い。また、切断工程で一度に切断される鋼板の数は限定されない。鋼板を一枚ずつ切断しても良い。複数の鋼板を一度に切断しても良い。 Next, in step S502, a cutting process is performed. In the cutting process, the steel plate manufactured in step S501 is cut. In this embodiment, the steel plate manufactured in step S501 is cut so that the shape of the plate surface of the steel plate after cutting becomes the planar shape of blocks 110a to 110e (the shape of the x-y plane shown in FIG. 1). A known method may be adopted as a method for cutting the steel plate. For example, the steel plate may be cut by punching. Also, the steel plate may be cut by laser processing. Also, the number of steel plates cut at one time in the cutting process is not limited. The steel plates may be cut one by one. Multiple steel plates may be cut at once.
　次に、ステップＳ５０３において、結晶粒測定工程が行われる。結晶粒測定工程では、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌを算出（測定）することと、（３）式を満たすか否かの確認と、を行う。本実施形態では、まず、ステップＳ５０２で切断された鋼板の鋼板対向端面上の結晶粒の数ｎと、当該鋼板対向端面の長さＬと、を測定する。そして、当該鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌを算出する。そして、当該鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌが（３）式を満たすか否かを判定する。例えば、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌを、ブロック対向端面１１１ａ～１１１ｐごとに算出する場合、（３）式を満たすか否かの判定は、ブロック対向端面１１１ａ～１１１ｐごとに行われる。この場合、一つのブロック対向端面の一部を構成する鋼板対向端面上の結晶粒の数ｎの代表値（例えば、算術平均値）、当該ブロック対向端面の一部を構成する鋼板対向端面の長さＬの代表値（例えば、算術平均値）が、それぞれ（３）式のｎ、Ｌとして用いられる。 Next, in step S503, a grain measurement process is performed. In the grain measurement process, the number of grains n/L per unit length on the steel plate facing end face is calculated (measured), and it is confirmed whether or not formula (3) is satisfied. In this embodiment, first, the number of grains n on the steel plate facing end face of the steel plate cut in step S502 and the length L of the steel plate facing end face are measured. Then, the number of grains n/L per unit length on the steel plate facing end face is calculated. Then, it is determined whether the number of grains n/L per unit length on the steel plate facing end face satisfies formula (3). For example, when the number of grains n/L per unit length on the steel plate facing end face is calculated for each of the block facing end faces 111a to 111p, the determination of whether or not formula (3) is satisfied is performed for each of the block facing end faces 111a to 111p. In this case, a representative value (e.g., the arithmetic mean value) of the number n of crystal grains on a steel plate facing end face that constitutes part of one block facing end face, and a representative value (e.g., the arithmetic mean value) of the length L of the steel plate facing end face that constitutes part of the block facing end face are used as n and L in formula (3), respectively.
　鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌの算出と、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌが（３）式を満たすか否かの判定と、のうちの少なくとも一方は、コンピュータで行われても良い。この場合、例えば、鋼板の鋼板対向端面上の結晶粒の数ｎと、該鋼板対向端面の長さＬと、を含む情報をコンピュータに入力しても良い。また、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌの算出と、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌが（３）式を満たすか否かの判定と、のうちの少なくとも一方は、人によって行われても良い。 At least one of the calculation of the number of crystal grains per unit length on the opposing end face of the steel plate n/L and the determination of whether the number of crystal grains per unit length on the opposing end face of the steel plate n/L satisfies formula (3) may be performed by a computer. In this case, for example, information including the number of crystal grains n on the opposing end face of the steel plate and the length L of the opposing end face of the steel plate may be input to a computer. Also, at least one of the calculation of the number of crystal grains per unit length on the opposing end face of the steel plate n/L and the determination of whether the number of crystal grains per unit length on the opposing end face of the steel plate n/L satisfies formula (3) may be performed manually.
　鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌが（３）式を満たさない場合、例えば、ステップＳ５０１が再び行われる。なお、この場合、（３）式を満たさない鋼板のみがステップＳ５０１で製造される。 If the number of crystal grains per unit length on the opposing end faces of the steel plate, n/L, does not satisfy formula (3), for example, step S501 is performed again. In this case, only steel plates that do not satisfy formula (3) are produced in step S501.
　全てのブロック対向端面１１１ａ～１１１ｐにおいて、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌが（３）式を満たす場合、ステップＳ５０４において、第１粗さ測定工程が行われる。第１粗さ測定工程では、ステップＳ５０２で切断された鋼板の面内方向表面粗さＲａ（Ｓ）を算出（測定）する。本実施形態では、まず、ステップＳ５０２で切断された鋼板の粗さ曲線を面内方向測定位置（仮想直線３０１ａ～３０１ｅの位置）において測定する。そして、面内方向測定位置での粗さ曲線に基づいて、面内方向表面粗さＲａ（Ｓ）を算出する。面内方向表面粗さＲａ（Ｓ）の算出は、例えば、ブロック１１０ａ～１１０ｅを構成する全ての鋼板において行われる。面内方向表面粗さＲａ（Ｓ）の算出は、コンピュータで行われても良い。また、面内方向表面粗さＲａ（Ｓ）の算出は、人によって行われても良い。 If the number of crystal grains per unit length n/L on the steel plate facing end faces of all the block facing end faces 111a to 111p satisfies formula (3), a first roughness measurement process is performed in step S504. In the first roughness measurement process, the in-plane surface roughness Ra(S) of the steel plate cut in step S502 is calculated (measured). In this embodiment, first, the roughness curve of the steel plate cut in step S502 is measured at the in-plane measurement position (the position of the virtual straight lines 301a to 301e). Then, based on the roughness curve at the in-plane measurement position, the in-plane surface roughness Ra(S) is calculated. The calculation of the in-plane surface roughness Ra(S) is performed, for example, for all the steel plates constituting the blocks 110a to 110e. The calculation of the in-plane surface roughness Ra(S) may be performed by a computer. The calculation of the in-plane surface roughness Ra(S) may also be performed by a person.
　次に、ステップＳ５０５において、第２粗さ測定工程が行われる。第２粗さ測定工程では、面内方向表面粗さＲａ（Ｓ）の測定対象の鋼板を有するブロックのブロック対向端面の積層方向表面粗さＲａ（Ｄ）を算出（測定）する。本実施形態では、まず、ステップＳ５０２で切断された鋼板から、或る一つのブロックを構成する全ての鋼板を取り出す。そして、当該ブロックを構成する鋼板の粗さ曲線を積層方向測定位置（仮想直線２０１ａ～２０１ｐ上の位置）において測定する。そして、積層方向測定位置での粗さ曲線に基づいて、積層方向表面粗さＲａ（Ｄ）を算出する。積層方向表面粗さＲａ（Ｄ）の算出は、例えば、積鉄心１００を構成する全てのブロック１１０ａ～１１０ｅの全てのブロック対向端面１１１ａ～１１１ｐにおいて行われる。積層方向表面粗さＲａ（Ｄ）の算出は、コンピュータで行われても良い。また、積層方向表面粗さＲａ（Ｄ）の算出は、人によって行われても良い。 Next, in step S505, a second roughness measurement process is performed. In the second roughness measurement process, the lamination direction surface roughness Ra(D) of the block facing end face of the block having the steel plate to be measured for the in-plane direction surface roughness Ra(S) is calculated (measured). In this embodiment, first, all the steel plates constituting a certain block are taken out from the steel plates cut in step S502. Then, the roughness curve of the steel plate constituting the block is measured at the lamination direction measurement position (position on the virtual straight lines 201a to 201p). Then, the lamination direction surface roughness Ra(D) is calculated based on the roughness curve at the lamination direction measurement position. The lamination direction surface roughness Ra(D) is calculated, for example, for all the block facing end faces 111a to 111p of all the blocks 110a to 110e constituting the stacked core 100. The lamination direction surface roughness Ra(D) may be calculated by a computer. Additionally, the calculation of the layer direction surface roughness Ra(D) may be performed manually.
　次に、ステップＳ５０６において、粗さ調整工程が行われる。粗さ調整工程では、一対のブロック対向端面のそれぞれにおいて（１）式（好ましくはさらに（２）式）を満たすか否かの判定と、（１）式（好ましくはさらに（２）式）を満たさないブロック対向端面の表面の粗さの調整と、が行われる。 Next, in step S506, a roughness adjustment process is performed. In the roughness adjustment process, it is determined whether or not each of the pair of opposing end faces of the blocks satisfies formula (1) (preferably also formula (2)), and the surface roughness of the opposing end faces of the blocks that do not satisfy formula (1) (preferably also formula (2)) is adjusted.
　本実施形態では、まず、一対のブロック対向端面（例えば、一対のブロック対向端面１１１ａおよび１１１ｉ）に対して算出（測定）した面内方向表面粗さＲａ（Ｓ）および積層方向表面粗さＲａ（Ｄ）を用いて、当該一対のブロック対向端面のそれぞれにおいて（１）式（好ましくはさらに（２）式）を満たすか否かを判定する。この判定は、例えば、ブロック１１０ａ～１１０ｅの全てのブロック対向端面１１１ａ～１１１ｐにおいて行われる。また、この判定は、コンピュータで行われても良い。また、この判定は、人によって行われても良い。 In this embodiment, first, the in-plane surface roughness Ra(S) and the stacking direction surface roughness Ra(D) calculated (measured) for a pair of block opposing end faces (e.g., a pair of block opposing end faces 111a and 111i) are used to determine whether or not each of the pair of block opposing end faces satisfies formula (1) (preferably also formula (2)). This determination is made, for example, for all block opposing end faces 111a to 111p of blocks 110a to 110e. This determination may also be made by a computer. This determination may also be made by a person.
　そして、（１）式（好ましくはさらに（２）式）を満たさない鋼板対向端面の粗さを調整する。鋼板の端面の粗さの調整は、例えば、ブロック１１０ａ～１１０ｅの全てのブロック対向端面１１１ａ～１１１ｐのうち、（１）式（好ましくはさらに（２）式）を満たさないブロック対向端面の全てにおいて行われる。 Then, the roughness of the steel plate facing end faces that do not satisfy formula (1) (and preferably formula (2)) is adjusted. The adjustment of the roughness of the steel plate end faces is performed, for example, on all of the block facing end faces 111a to 111p of blocks 110a to 110e that do not satisfy formula (1) (and preferably formula (2)).
　そして、以上のようにして粗さが調整されたブロック対向端面において（１）式（好ましくはさらに（２）式）を満たすか否かを再び判定する。（１）式（好ましくはさらに（２）式）を満たすか否の判定と、鋼板の端面の粗さの調整と、は（１）式（好ましくはさらに（２）式）を満たさないブロック対向端面がなくなるまで繰り返される。 Then, it is determined again whether the block-facing end faces whose roughness has been adjusted in the above manner satisfy formula (1) (and preferably formula (2)). The determination of whether formula (1) (and preferably formula (2)) is satisfied and the adjustment of the roughness of the steel plate end faces are repeated until there are no block-facing end faces that do not satisfy formula (1) (and preferably formula (2)).
　以上のように本実施形態では、少なくとも一つの一対のブロック対向端面（例えば、一対のブロック対向端面１１１ａおよび１１１ｉ）のそれぞれにおいて、１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２を満たすようにする。したがって、鋼板とは別の材料を用いなくても振動を抑制することができる積鉄心を提供することができる。また、１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２を、６≦Ｒａ（Ｄ）／Ｒａ（Ｓ）≦８とすれば、積鉄心１００の騒音の抑制効果をより確実に高めることができる。 As described above, in this embodiment, at least one pair of block opposing end faces (for example, a pair of block opposing end faces 111a and 111i) is made to satisfy 1<Ra(D)/Ra(S)≦12. Therefore, it is possible to provide a stacked core that can suppress vibration without using a material other than steel plate. Furthermore, if 1<Ra(D)/Ra(S)≦12 is changed to 6≦Ra(D)/Ra(S)≦8, the noise suppression effect of the stacked core 100 can be more reliably improved.
　また、本実施形態では、少なくとも一つの一対のブロック対向端面（例えば、ブロック対向端面１１１ａおよび１１１ｉ）のうち少なくとも一方において、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌを０．５以下とする。したがって、積鉄心の振動をより抑制することができる。 In addition, in this embodiment, the number of crystal grains per unit length on the steel plate facing end surface, n/L, is set to 0.5 or less on at least one of at least one pair of block facing end surfaces (e.g., block facing end surfaces 111a and 111i). Therefore, vibration of the stacked core can be further suppressed.
　なお、以上説明した本発明の実施形態は、何れも本発明を実施するにあたっての具体化の例を示したものに過ぎず、これらによって本発明の技術的範囲が限定的に解釈されてはならないものである。すなわち、本発明はその技術思想、またはその主要な特徴から逸脱することなく、様々な形で実施することができる。 The above-described embodiments of the present invention are merely examples of how the present invention can be implemented, and the technical scope of the present invention should not be interpreted in a limiting manner. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features.
　以下に、本発明の実施例を説明する。なお、本発明は、本実施例に限定されない。すなわち、本実施例に示す各種の条件は、本発明の実施可能性および効果等を確認するために採用した条件例である。したがって、本発明は、本実施例で示す条件例に限定されない。また、本発明は、本発明の要旨を逸脱せず、本発明の目的を達成する限りにおいて、種々の条件を採用し得る。 Below, an embodiment of the present invention will be described. Note that the present invention is not limited to this embodiment. In other words, the various conditions shown in this embodiment are example conditions adopted to confirm the feasibility and effects of the present invention. Therefore, the present invention is not limited to the example conditions shown in this embodiment. Furthermore, various conditions may be adopted in the present invention as long as they do not deviate from the gist of the present invention and achieve the object of the present invention.
（方向性電磁鋼板）
　表１に示す化学組成を有する鋼種Ａ～Ｅのスラブを用いて一方向性電磁鋼板をそれぞれ製造した。表１に示す値の単位は、質量％である。また、各スラブの残部（表１に示している化学成分以外の化学成分）はＦｅである。 (Grain-oriented electrical steel sheet)
Grain-oriented electrical steel sheets were produced using slabs of steel types A to E having the chemical compositions shown in Table 1. The units of values shown in Table 1 are mass %. The balance of each slab (chemical components other than those shown in Table 1) is Fe.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　鋼種Ａ～Ｅのスラブを用いて、表２に示す製造工程および製造条件で方向性電磁鋼板を製造した。 Grain-oriented electrical steel sheets were manufactured using slabs of steel types A to E using the manufacturing process and conditions shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２に示すように、熱間圧延工程、熱延板焼鈍工程、冷間圧延工程、脱炭焼鈍工程、窒化処理（窒化焼鈍）工程、仕上焼鈍工程を、この順で表２に示す製造条件で実施した。 As shown in Table 2, the hot rolling process, hot-rolled sheet annealing process, cold rolling process, decarburization annealing process, nitriding treatment (nitriding annealing) process, and finish annealing process were carried out in this order under the manufacturing conditions shown in Table 2.
　本実施例では、脱炭焼鈍後の冷延鋼板に対して、水素－窒素－アンモニアの混合雰囲気下で窒化処理（窒化焼鈍）を施した。アンモニア窒化によりアンモニアの流量を調整することにより窒化量を調整した。さらに、主成分をマグネシアまたはアルミナとする焼鈍分離剤を冷延鋼板に塗布し、仕上げ焼鈍を実行した。焼鈍分離剤として、主成分を含む成分の混合割合が異なる複数種類の焼鈍分離剤を用いた。また、仕上げ焼鈍時の焼鈍温度と、焼鈍温度における保持時間と、を調整した。本実施例では、窒化処理における窒化量と、仕上げ焼鈍時の焼鈍温度および保持時間と、により、仕上焼鈍後の鋼板の結晶粒径を制御した。 In this example, the cold-rolled steel sheet after decarburization annealing was subjected to nitriding treatment (nitriding annealing) in a mixed atmosphere of hydrogen, nitrogen, and ammonia. The amount of nitriding was adjusted by adjusting the flow rate of ammonia using ammonia nitriding. In addition, an annealing separator containing magnesia or alumina as its main component was applied to the cold-rolled steel sheet, and finish annealing was performed. As the annealing separator, multiple types of annealing separators with different mixture ratios of components including the main component were used. In addition, the annealing temperature during finish annealing and the holding time at the annealing temperature were adjusted. In this example, the crystal grain size of the steel sheet after finish annealing was controlled by the amount of nitriding in the nitriding treatment and the annealing temperature and holding time during finish annealing.
　仕上げ焼鈍後の鋼板の表面に形成された一次被膜の上に、絶縁被膜コーティング溶液を塗布した。絶縁被膜コーティング溶液として、燐酸塩とコロイド状シリカとを主成分とする溶液であって、クロムを含有する溶液を用いた。絶縁被膜コーティング溶液が塗布された鋼板を熱処理することにより、絶縁被膜を形成した。本実施例では、以上のようにして鋼種Ａ～Ｅのスラブから一方向性電磁鋼板をそれぞれ製造した。以下の説明では、鋼種Ａ～Ｅのスラブから製造された一方向性電磁鋼板を、必要に応じて、鋼種Ａ～Ｅの鋼板と称する。 An insulating coating solution was applied onto the primary coating formed on the surface of the steel sheet after final annealing. A solution containing chromium and whose main components were phosphate and colloidal silica was used as the insulating coating solution. The steel sheet to which the insulating coating solution was applied was heat treated to form an insulating coating. In this example, grain-oriented electrical steel sheets were manufactured from slabs of steel types A to E in the manner described above. In the following explanation, the grain-oriented electrical steel sheets manufactured from slabs of steel types A to E will be referred to as steel sheets of steel types A to E as necessary.
（積鉄心）
　鋼種Ａの鋼板を素材として、図１に示す形状を有する積鉄心１００を製造した。本発明者らは、（１）式に示すＲａ（Ｄ）／Ｒａ（Ｓ）と、クリアランスと、には正比例の関係があるという知見を得た。本実施例では、この知見に基づき、ブロック１１０ａ～１１０ｅの平面形状を得るために鋼種Ａの鋼板を切断する際に、せん断機の上下の刃のクリアランスを制御することにより、鋼種Ａの鋼板の端面の粗さを調整した。ブロック１１０ａ～１１０ｅの平面形状を有する鋼種Ａの鋼板を積層して各ブロック１１０ａ～１１０ｅを製造した。その際、ブロック１１０ａ～１１０ｅの組として、ブロック対向端面１１１ａ～１１１ｐの粗さが相互に異なる複数組のブロック１１０ａ～１１０ｅを製造した。鋼種Ｂ～Ｅの鋼板についても同様にして複数組のブロック１１０ａ～１１０ｅをそれぞれ複数製造した。 (Stacked core)
A stacked core 100 having the shape shown in FIG. 1 was manufactured using steel plates of steel type A as a material. The inventors have found that there is a directly proportional relationship between Ra(D)/Ra(S) shown in formula (1) and the clearance. In this embodiment, based on this finding, when cutting the steel plate of steel type A to obtain the planar shapes of the blocks 110a to 110e, the roughness of the end surface of the steel plate of steel type A was adjusted by controlling the clearance between the upper and lower blades of a shearing machine. The steel plates of steel type A having the planar shapes of the blocks 110a to 110e were stacked to manufacture the blocks 110a to 110e. At that time, as a set of the blocks 110a to 110e, a plurality of sets of blocks 110a to 110e in which the roughness of the block facing end surfaces 111a to 111p differed from each other were manufactured. Similarly, a plurality of sets of blocks 110a to 110e were manufactured for the steel plates of steel types B to E.
　以下の説明では、鋼種Ａ～Ｅの鋼板から製造されたブロックを、必要に応じて、鋼種Ａ～Ｅのブロックと称する。また、以下の説明では、ブロック１１０ａ、ブロック１１０ｂ、ブロック１１０ｃ、ブロック１１０ｄ、ブロック１１０ｅを、必要に応じて、上ブロック１１０ａ、下ブロック１１０ｂ、左ブロック１１０ｃ、中央ブロック１１０ｄ、右ブロック１１０ｅと称する。 In the following explanation, blocks manufactured from steel plates of steel types A to E will be referred to as blocks of steel types A to E, as necessary. Also, in the following explanation, blocks 110a, 110b, 110c, 110d, and 110e will be referred to as upper block 110a, lower block 110b, left block 110c, center block 110d, and right block 110e, as necessary.
　同じ鋼種の鋼板から製造されたブロック１１０ａ～１１０ｅを組み合わせて積鉄心１００を製造した。以下の説明では、このようにして製造された積鉄心１００を、必要に応じて、鋼種Ａ～Ｅの積鉄心１００と称する。また、左ブロック１１０ｃ、中央ブロック１１０ｄ、および右ブロック１１０ｅと、上ブロック１１０ａおよび下ブロック１１０ｂと、を異なる鋼種の鋼板から製造されたブロックとして、ブロック１１０ａ～１１０ｅを組み合わせて積鉄心１００を製造した。具体的に、鋼種Ａ、Ｂの積鉄心１００と、鋼種Ａ、Ｄの積鉄心１００と、鋼種Ｂ、Ｃの積鉄心１００と、鋼種Ｂ、Ｅの積鉄心１００と、を製造した。鋼種Ａ、Ｂの積鉄心１００は、左ブロック１１０ｃ、中央ブロック１１０ｄ、および右ブロック１１０ｅが鋼種Ａであり、且つ、上ブロック１１０ａおよび下ブロック１１０ｂが鋼種Ｂである積鉄心である。鋼種Ａ、Ｄの積鉄心１００は、左ブロック１１０ｃ、中央ブロック１１０ｄ、および右ブロック１１０ｅが鋼種Ａであり、且つ、上ブロック１１０ａおよび下ブロック１１０ｂが鋼種Ｄである積鉄心である。鋼種Ｂ、Ｃの積鉄心１００は、左ブロック１１０ｃ、中央ブロック１１０ｄ、および右ブロック１１０ｅが鋼種Ｂであり、且つ、上ブロック１１０ａおよび下ブロック１１０ｂが鋼種Ｃである積鉄心である。鋼種Ｂ、Ｅの積鉄心１００は、左ブロック１１０ｃ、中央ブロック１１０ｄ、および右ブロック１１０ｅが鋼種Ｅであり、且つ、上ブロック１１０ａおよび下ブロック１１０ｂが鋼種Ｂである積鉄心である。 The stacked core 100 was manufactured by combining blocks 110a-110e manufactured from steel plates of the same steel type. In the following explanation, the stacked core 100 manufactured in this manner will be referred to as stacked core 100 of steel types A-E as necessary. Furthermore, the left block 110c, center block 110d, and right block 110e, and the upper block 110a and lower block 110b were considered as blocks manufactured from steel plates of different steel types, and the stacked core 100 was manufactured by combining blocks 110a-110e. Specifically, stacked cores 100 of steel types A and B, stacked cores 100 of steel types A and D, stacked cores 100 of steel types B and C, and stacked cores 100 of steel types B and E were manufactured. The stacked core 100 of steel types A and B is a stacked core in which the left block 110c, the center block 110d, and the right block 110e are made of steel type A, and the upper block 110a and the lower block 110b are made of steel type B. The stacked core 100 of steel types A and D is a stacked core in which the left block 110c, the center block 110d, and the right block 110e are made of steel type A, and the upper block 110a and the lower block 110b are made of steel type D. The stacked core 100 of steel types B and C is a stacked core in which the left block 110c, the center block 110d, and the right block 110e are made of steel type B, and the upper block 110a and the lower block 110b are made of steel type C. The stacked core 100 of steel types B and E is a stacked core in which the left block 110c, the center block 110d, and the right block 110e are made of steel type E, and the upper block 110a and the lower block 110b are made of steel type B.
　積鉄心１００の幅（ｙ軸方向の長さ）、高さ（ｘ軸方向の長さ）、厚み（ｚ軸方向の長さ）は、それぞれ、７５０ｍｍ、７５０ｍｍ、約４１ｍｍであった。また、上ブロック１１０ａおよび下ブロック１１０ｂの幅（ｘ軸方向の長さ）と、左ブロック１１０ｃ、中央ブロック１１０ｄ、および右ブロック１１０ｅの幅（ｙ軸方向の長さ）は、１５０ｍｍであった。 The width (length in the y-axis direction), height (length in the x-axis direction), and thickness (length in the z-axis direction) of the stacked core 100 were 750 mm, 750 mm, and approximately 41 mm, respectively. In addition, the widths (lengths in the x-axis direction) of the upper block 110a and the lower block 110b, and the widths (lengths in the y-axis direction) of the left block 110c, the center block 110d, and the right block 110e were 150 mm.
（評価方法）
　ブロック１１０ａ～１１０ｅの平面形状を有する鋼種Ａ～Ｅの鋼板の鋼板対向端面の長さＬ（Ｌ１～Ｌ１５）をノギスで測定した。また、当該鋼板の鋼板対向端面（せん断面）を５％ナイタール溶液で１００秒間～３００秒間、腐食させた。その後、当該鋼板対向端面を、オリンパス株式会社製の工業用顕微鏡 BX53Mで観察することにより、当該鋼板対向端面に存在する結晶粒界の数を計数した。そして、計数した数に１を加算して、当該鋼板対向端面上の結晶粒の数ｎを算出した。同一の鋼板から得られた、鋼板対向端面の長さＬと、鋼板対向端面上の結晶粒の数ｎと、から、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌを算出した。ブロック１１０ａ～ブロック１１０ｅを構成する全ての鋼板について、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌを個別に算出した。そして、ブロック対向端面１１１ａ～１１１ｐごとに、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌの算術平均値を算出した。一つのブロック対向端面において算出した鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌの算術平均値を、当該ブロック対向端面における鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌとした。 (Evaluation method)
The lengths L (L1 to L15) of the steel plate facing end faces of the steel plates of steel types A to E having the planar shapes of the blocks 110a to 110e were measured with a vernier caliper. In addition, the steel plate facing end faces (sheared surfaces) of the steel plates were corroded with a 5% nital solution for 100 to 300 seconds. The steel plate facing end faces were then observed with an industrial microscope BX53M manufactured by Olympus Corporation to count the number of crystal grain boundaries present on the steel plate facing end faces. The number of crystal grains n on the steel plate facing end faces was calculated by adding 1 to the counted number. The number of crystal grains n/L per unit length on the steel plate facing end faces was calculated from the length L of the steel plate facing end faces and the number of crystal grains n on the steel plate facing end faces obtained from the same steel plate. The number of crystal grains n/L per unit length on the steel plate facing end faces was calculated individually for all the steel plates constituting the blocks 110a to 110e. Then, the arithmetic mean value of the number n/L of crystal grains per unit length on the steel plate facing end face was calculated for each of the block facing end faces 111a to 111p. The arithmetic mean value of the number n/L of crystal grains per unit length on the steel plate facing end face calculated for one block facing end face was taken as the number n/L of crystal grains per unit length on the steel plate facing end face for that block facing end face.
　また、前述したようにして製造された各積鉄心１００（鋼種Ａ～Ｅの積鉄心１００、鋼種Ａ、Ｂの積鉄心、鋼種Ａ、Ｄの積鉄心１００、鋼種Ｂ、Ｃの積鉄心１００、鋼種Ｂ、Ｅの積鉄心）のそれぞれについて、ＪＩＳ　Ｂ　０６０１：２０１３に準拠して、積層方向表面粗さＲａ（Ｄ）および面内方向表面粗さＲａ（Ｓ）を算出した。 Furthermore, for each of the stacked cores 100 manufactured as described above (stacked cores 100 of steel types A to E, stacked cores 100 of steel types A and B, stacked cores 100 of steel types A and D, stacked cores 100 of steel types B and C, stacked cores of steel types B and E), the lamination direction surface roughness Ra(D) and in-plane direction surface roughness Ra(S) were calculated in accordance with JIS B 0601:2013.
　各積鉄心１００の各ブロック対向端面１１１ａ～１１１ｐについて、当該ブロック対向端面を構成する複数の鋼板を一枚ずつ抜き取り、抜き取った鋼板の積層方向測定位置（仮想直線２０１ａ～２０１ｐ上の位置）において、積層方向表面粗さＲａ（Ｄ）を、株式会社キーエンス製のワンショット3D形状測定機（型式名；VR-6000）を用いて測定した。そして、同一のブロック対向端面を構成する複数の鋼板から算出された、当該ブロック対向端面の積層方向表面粗さＲａ（Ｄ）の算術平均値を当該ブロック対向端面の積層方向表面粗さＲａ（Ｄ）として算出した。 For each block facing end face 111a-111p of each stacked core 100, the multiple steel plates constituting that block facing end face were extracted one by one, and the stacking direction surface roughness Ra(D) of the extracted steel plate was measured at the stacking direction measurement position (position on the imaginary line 201a-201p) using a one-shot 3D shape measuring instrument (model name: VR-6000) manufactured by Keyence Corporation. The arithmetic average value of the stacking direction surface roughness Ra(D) of that block facing end face calculated from the multiple steel plates constituting the same block facing end face was calculated as the stacking direction surface roughness Ra(D) of that block facing end face.
　また、各積鉄心１００の各ブロック対向端面１１１ａ～１１１ｐについて、当該ブロック対向端面を構成する複数の鋼板を一枚ずつ抜き取り、抜き取った鋼板の面内方向測定位置（仮想直線３０１ａ～３０１ｅ上の位置）において、面内方向表面粗さＲａ（Ｓ）を、株式会社キーエンス製のワンショット3D形状測定機（型式名；VR-6000）を用いて測定した。そして、同一のブロック対向端面を構成する複数の鋼板から算出された、当該ブロック対向端面の面内方向表面粗さＲａ（Ｓ）の算術平均値を当該ブロック対向端面の面内方向表面粗さＲａ（Ｓ）として算出した。 Furthermore, for each block facing end face 111a-111p of each stacked core 100, the multiple steel plates constituting that block facing end face were extracted one by one, and the in-plane surface roughness Ra(S) of the extracted steel plate was measured at the in-plane measurement positions (positions on the imaginary lines 301a-301e) using a one-shot 3D shape measuring instrument (model name: VR-6000) manufactured by Keyence Corporation. The arithmetic average value of the in-plane surface roughness Ra(S) of that block facing end face calculated from the multiple steel plates constituting the same block facing end face was calculated as the in-plane surface roughness Ra(S) of that block facing end face.
　そして、同一のブロック対向端面における積層方向表面粗さＲａ（Ｄ）および面内方向表面粗さＲａ（Ｓ）から、当該ブロック対向端面のＲａ（Ｄ）／Ｒａ（Ｓ）を算出した。このようなＲａ（Ｄ）／Ｒａ（Ｓ）の算出を、前述したようにして製造した全ての積鉄心１００の全てのブロック対向端面１１１ａ～１１１ｐに対して行った。 Then, Ra(D)/Ra(S) of the same block opposing end face was calculated from the lamination direction surface roughness Ra(D) and the in-plane direction surface roughness Ra(S) of that block opposing end face. This calculation of Ra(D)/Ra(S) was performed for all block opposing end faces 111a to 111p of all stacked cores 100 manufactured as described above.
　各積鉄心１００（鋼種Ａ～Ｅの積鉄心１００、鋼種Ａ、Ｂの積鉄心、鋼種Ａ、Ｄの積鉄心１００、鋼種Ｂ、Ｃの積鉄心１００、鋼種Ｂ、Ｅの積鉄心）の騒音を測定した。具体的に、暗騒音が１６ｄＢＡの無響室内で、騒音計を積鉄心１００の表面から０．３ｍ離れた位置に設置した。聴感補正としてＡ特性を使用して、当該騒音計により積鉄心１００の騒音を測定した。その際、励磁周波数＝５０Ｈｚ、積鉄心１００内の磁束密度＝１．７Ｔの励磁条件で積鉄心１００を励磁した。表３および表４に、このようにして得られた各積鉄心１００のｎ／Ｌ、Ｒａ（Ｄ）／Ｒａ（Ｓ）、騒音の値を示す。表１において、１１１ａ～１１１ｐは、図１、図２Ａ～図２Ｅ、図３Ａ～図３Ｅ、および図４Ａ～図４Ｅに示したブロック対向端面１１１ａ～１１１ｐであることを示す。 The noise of each stacked core 100 (stacked cores 100 of steel types A to E, stacked cores of steel types A and B, stacked cores 100 of steel types A and D, stacked cores 100 of steel types B and C, stacked cores of steel types B and E) was measured. Specifically, a sound level meter was placed 0.3 m away from the surface of the stacked core 100 in an anechoic chamber with a background noise level of 16 dBA. The noise of the stacked core 100 was measured with the sound level meter using A-weighting as a hearing correction. At that time, the stacked core 100 was excited under the excitation conditions of excitation frequency = 50 Hz, magnetic flux density inside the stacked core 100 = 1.7 T. Tables 3 and 4 show the n/L, Ra(D)/Ra(S) and noise values of each stacked core 100 obtained in this manner. In Table 1, 111a to 111p indicate the block facing end surfaces 111a to 111p shown in Figures 1, 2A to 2E, 3A to 3E, and 4A to 4E.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表３および表４に示すように、同種の鋼種の積鉄心１００において、１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２を満たす一対のブロック対向端面１１１ａおよび１１１ｉ、１１１ｂおよび１１１ｌ、１１１ｃおよび１１１ｍ、１１１ｄおよび１１１ｎ、１１１ｅおよび１１１ｋ、１１１ｆおよび１１１ｊ、１１１ｇおよび１１１ｏ、１１１ｈおよび１１１ｐの数が１以上である場合の方が０（零）である場合よりも騒音は低下した。すなわち、鋼種Ａについて、番号１、１４～１５に比べて、番号２～１３、１６～２０の方が、騒音が低下した。鋼種Ｂについて、番号２１に比べて、番号２５、２９、３３、３７、４１の方が、騒音が低下した。鋼種Ｃについて、番号２２に比べて、番号２６、３０、３４、３８、４２の方が、騒音が低下した。鋼種Ｄについて、番号２３に比べて、番号２７、３１、３５、３９、４３の方が、騒音が低下した。鋼種Ｅについて、番号２４に比べて、番号２８、３２、３６、４０、４４の方が、騒音が低下した。 As shown in Tables 3 and 4, in stacked cores 100 of the same steel type, when the number of pairs of block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p, which satisfy 1 < Ra(D)/Ra(S) ≦ 12, is 1 or more, noise is lower than when the number is 0 (zero). In other words, for steel type A, noise was lower for numbers 2 to 13 and 16 to 20 compared to numbers 1 and 14 to 15. For steel type B, noise was lower for numbers 25, 29, 33, 37, and 41 compared to number 21. For steel type C, noise was lower for numbers 26, 30, 34, 38, and 42 compared to number 22. For steel type D, numbers 27, 31, 35, 39, and 43 had lower noise levels than number 23. For steel type E, numbers 28, 32, 36, 40, and 44 had lower noise levels than number 24.
　また、同種の鋼種の積鉄心１００において、１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２を満たす一対のブロック対向端面の数が、一対のブロック対向端面の総数（本実施例では８（表３および表４の「Ｒａ（Ｄ）／Ｒａ（Ｓ）」の欄の数では１６））の１／２倍以上になると、騒音の低減効果が大きなった。すなわち、鋼種Ａについて、番号２、３、５、７、１６、１７、１９に比べて、番号４、６、８～１３、１８、１９～２０の方が、騒音が低下した。鋼種Ｂについて、番号３７、４１に比べて、番号２５、２９、３３の方が、騒音が低下した。鋼種Ｃについて、番号３８、４２に比べて、番号２６、３０、３４の方が、騒音が低下した。鋼種Ｄについて、番号３９、４３に比べて、番号２７、３１、３５の方が、騒音が低下した。鋼種Ｅについて、番号４０、４４に比べて、番号２８、３２、３６の方が、騒音が低下した。 Furthermore, in stacked cores 100 of the same steel type, when the number of pairs of opposing block end faces that satisfy 1 < Ra(D)/Ra(S) ≦ 12 was more than half the total number of pairs of opposing block end faces (8 in this embodiment (16 in the number in the "Ra(D)/Ra(S)" column in Tables 3 and 4)), the noise reduction effect was large. That is, for steel type A, numbers 4, 6, 8-13, 18, and 19-20 had lower noise than numbers 2, 3, 5, 7, 16, 17, and 19. For steel type B, numbers 25, 29, and 33 had lower noise than numbers 37 and 41. For steel type C, numbers 26, 30, and 34 had lower noise than numbers 38 and 42. For steel type D, numbers 27, 31, and 35 had lower noise than numbers 39 and 43. For steel type E, numbers 28, 32, and 36 produced less noise than numbers 40 and 44.
　また、同種の鋼種の積鉄心１００において、６≦Ｒａ（Ｄ）／Ｒａ（Ｓ）≦８を満たす一対のブロック対向端面の箇所があると、より騒音が低下し、その数が一対のブロック対向端面の総数（本実施例では８（表３および表４の「Ｒａ（Ｄ）／Ｒａ（Ｓ）」の欄の数では１６））の１／２倍以上になると、騒音の低減効果が大きくなった。すなわち、鋼種Ａについて、番号２～７、１０、１３、１６～１８に比べて番号８、９、１１、１２、１９、２０の方が、騒音が低下し、番号１９、２０に比べて、番号８、９、１１、１２の方が、騒音が低下した。鋼種Ｂについて、番号２５、３３、３７、４１に比べて、番号２９の方が、騒音が低下した。鋼種Ｃについて、番号２６、３４、３８、４２に比べて、番号３０の方が、騒音が低下した。鋼種Ｄについて、番号２７、３５、３９、４３に比べて、番号３１の方が、騒音が低下した。鋼種Ｅについて、番号２８、３６、４０、４４に比べて、番号３２の方が、騒音が低下した。 Furthermore, in stacked cores 100 of the same steel type, when there are locations of a pair of opposing block end faces where 6≦Ra(D)/Ra(S)≦8, noise is further reduced, and when the number of such locations is equal to or more than half the total number of pairs of opposing block end faces (8 in this embodiment (16 in the number in the "Ra(D)/Ra(S)" column in Tables 3 and 4)), the noise reduction effect is greater. That is, for steel type A, numbers 8, 9, 11, 12, 19, and 20 showed lower noise levels than numbers 2 to 7, 10, 13, and 16 to 18, and numbers 8, 9, 11, and 12 showed lower noise levels than numbers 19 and 20. For steel type B, number 29 showed lower noise levels than numbers 25, 33, 37, and 41. For steel type C, number 30 showed lower noise levels than numbers 26, 34, 38, and 42. For steel type D, number 31 produced less noise than numbers 27, 35, 39, and 43. For steel type E, number 32 produced less noise than numbers 28, 36, 40, and 44.
　また、Ｒａ（Ｄ）／Ｒａ（Ｓ）の条件が同じであれば、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌが、０．５以下の鋼種Ｂ～Ｅの方が、０．５超の鋼種Ａよりも、騒音が低下した。すなわち、番号４（鋼種Ａ）に比べて番号２５～２８（鋼種Ｂ～Ｅ）の方が、騒音が低下した。また、番号１２（鋼種Ａ）に比べて番号２９～３２（鋼種Ｂ～Ｅ）の方が、騒音が低下した。また、番号１３（鋼種Ａ）に比べて番号３３～３６（鋼種Ｂ～Ｅ）の方が、騒音が低下した。 Also, if the Ra(D)/Ra(S) condition is the same, steel types B to E, in which the number of crystal grains per unit length on the opposing end faces of the steel plate, n/L, is 0.5 or less, have lower noise levels than steel type A, in which the number is over 0.5. In other words, numbers 25 to 28 (steel types B to E) have lower noise levels than number 4 (steel type A). Also, numbers 29 to 32 (steel types B to E) have lower noise levels than number 12 (steel type A). Also, numbers 33 to 36 (steel types B to E) have lower noise levels than number 13 (steel type A).
　また、異種の鋼種の組み合わせを選択することにより、１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２を満たすブロック対向端面の数を増やすことと、鋼板対向端面上の単位長さ当たりの結晶粒の数ｎ／Ｌが、０．５以下のブロック対向端面の数を増やすこととを実現することができ、これにより、騒音の低下効果を得ることができた。すなわち、番号２（鋼種Ａ）に比べて番号４５、４６（鋼種Ａ、Ｂ）の方が、騒音が低下した。番号２１（鋼種Ｂ）、２２（鋼種Ｃ）に比べて番号４７（番号Ｂ、Ｃ）の方が、騒音が低下した。番号２１（鋼種Ｂ）、２６（鋼種Ｅ）に比べて番号４８（番号Ｂ、Ｅ）の方が、騒音が低下した。 Also, by selecting a combination of different steel types, it was possible to increase the number of block facing end faces that satisfy 1<Ra(D)/Ra(S)≦12, and to increase the number of block facing end faces where the number of crystal grains per unit length on the steel plate facing end face, n/L, is 0.5 or less, thereby achieving a noise reduction effect. That is, noise was reduced in numbers 45 and 46 (steel types A and B) compared to number 2 (steel type A). Noise was reduced in number 47 (numbers B and C) compared to numbers 21 (steel type B) and 22 (steel type C). Noise was reduced in number 48 (numbers B and E) compared to numbers 21 (steel type B) and 26 (steel type E).
　本発明は、例えば、鉄心を備える機器に利用することができる。 The present invention can be used, for example, in equipment that has an iron core.

Claims (4)

  1. 　積層された複数の鋼板をそれぞれが有する複数のブロックを備え、
    　前記複数のブロックは、ブロック対向端面を有し、
    　前記ブロック対向端面は、前記ブロックの端面のうち、他の前記ブロックと相互に対向する位置にある端面であり、
    　少なくとも一つの一対の前記ブロック対向端面のそれぞれにおいて、以下の（Ａ）式を満たし、
    　前記一対のブロック対向端面は、相互に対向する位置に配置される二つの前記ブロック対向端面であることを特徴とする積鉄心。
    　１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２　・・・（Ａ）
    　ここで、Ｒａ（Ｄ）は、前記ブロック対向端面の、前記鋼板の積層方向における表面粗さＲａ（μｍ）であり、Ｒａ（Ｓ）は、当該ブロック対向端面の一部を構成する端面を有する前記鋼板の板面の、当該鋼板に流れる主磁束の方向または当該鋼板の圧延方向における表面粗さＲａ（μｍ）である。     A plurality of blocks each having a plurality of stacked steel plates are provided,
    The plurality of blocks have block opposing end surfaces,
    The block facing end surface is an end surface of the block that faces another block,
    At least one pair of the block opposing end faces each satisfy the following formula (A):
    A stacked core, wherein the pair of opposed end faces of the blocks are two opposed end faces of the blocks arranged in positions opposite to each other.
    1<Ra(D)/Ra(S)≦12 ... (A)
    Here, Ra(D) is the surface roughness Ra (μm) of the block-facing end face in the stacking direction of the steel plate, and Ra(S) is the surface roughness Ra (μm) of the plate surface of the steel plate having an end face that constitutes part of the block-facing end face, in the direction of the main magnetic flux flowing through the steel plate or the rolling direction of the steel plate.
  2. 　前記少なくとも一つの一対のブロック対向端面のそれぞれにおいて、以下の（Ｂ）式を満たすことを特徴とする請求項１に記載の積鉄心。
    　６≦Ｒａ（Ｄ）／Ｒａ（Ｓ）≦８　・・・（Ｂ）     2. The stacked core according to claim 1, wherein the following formula (B) is satisfied in each of the at least one pair of opposing end faces of the blocks:
    6≦Ra(D)/Ra(S)≦8 ... (B)
  3. 　前記少なくとも一つの一対のブロック対向端面のうちの少なくとも一つの前記ブロック対向端面において、以下の（Ｃ）式を満たすことを特徴とする請求項１または２に記載の積鉄心。
    　ｎ／Ｌ≦０．５　・・・（Ｃ）
    　ここで、ｎは、前記ブロック対向端面の一部を構成する前記鋼板に存在する結晶粒のうち、当該端面を境界として含む結晶粒の数（個）であり、Ｌは、当該端面の長さ（ｍｍ）である。     3. The stacked core according to claim 1, wherein the following formula (C) is satisfied in at least one of the at least one pair of block opposing end faces:
    n / L ≦ 0.5 ... (C)
    Here, n is the number (pieces) of crystal grains present in the steel plate constituting a part of the block-opposing end face that include the end face as a boundary, and L is the length (mm) of the end face.
  4. 　積層された複数の鋼板をそれぞれが有する複数のブロックを備えた積鉄心の製造方法であって、
    　鋼板を切断する切断工程と、
    　前記切断工程で切断された鋼板の板面の表面粗さＲａ（Ｓ）（μｍ）を測定する第１粗さ測定工程と、
    　前記表面粗さＲａ（Ｓ）の測定対象の前記鋼板を有する前記ブロックのブロック対向端面の表面粗さＲａ（Ｄ）（μｍ）を測定する第２粗さ測定工程と、
    　前記第１粗さ測定工程により測定されたＲａ（Ｓ）に対する前記第２粗さ測定工程により測定された表面粗さＲａ（Ｄ）の比Ｒａ（Ｄ）／Ｒａ（Ｓ）が、１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２を満たさない場合、前記ブロック対向端面の表面粗さを調整する粗さ調整工程と、
    を備え、
    　前記表面粗さＲａ（Ｓ）は、前記積鉄心が励磁された場合に前記鋼板に流れる主磁束の方向における表面粗さＲａ（μｍ）、または、前記鋼板の圧延方向における表面粗さＲａ（μｍ）であり、
    　前記表面粗さＲａ（Ｄ）は、前記鋼板の積層方向における表面粗さＲａ（μｍ）であり、
    　前記ブロック対向端面は、前記ブロックの端面のうち、前記積鉄心において他の前記ブロックと相互に対向する位置にある端面であり、
    　前記粗さ調整工程では、少なくとも一つの一対の前記ブロック対向端面のそれぞれにおいて、１＜Ｒａ（Ｄ）／Ｒａ（Ｓ）≦１２を満たすように、前記ブロック対向端面の表面粗さを調整し、
    　前記一対のブロック対向端面は、相互に対向する位置に配置される二つの前記ブロック対向端面である、積鉄心の製造方法。     A method for manufacturing a stacked core including a plurality of blocks each having a plurality of stacked steel plates, comprising the steps of:
    a cutting step of cutting the steel plate;
    A first roughness measuring step of measuring a surface roughness Ra (S) (μm) of the sheet surface of the steel sheet cut in the cutting step;
    a second roughness measuring step of measuring a surface roughness Ra(D) (μm) of a block-facing end surface of the block having the steel plate whose surface roughness Ra(S) is to be measured;
    a roughness adjusting step of adjusting the surface roughness of the block facing end face when a ratio Ra(D)/Ra(S) of the surface roughness Ra(D) measured in the second roughness measuring step to the surface roughness Ra(S) measured in the first roughness measuring step does not satisfy 1<Ra(D)/Ra(S)≦12;
    Equipped with
    The surface roughness Ra (S) is the surface roughness Ra (μm) in the direction of a main magnetic flux flowing through the steel plate when the stacked core is excited, or the surface roughness Ra (μm) in the rolling direction of the steel plate,
    The surface roughness Ra (D) is the surface roughness Ra (μm) in the lamination direction of the steel plate,
    the block opposing end surface is an end surface of the block that is located opposite to another block in the stacked core,
    In the roughness adjusting step, the surface roughness of each of at least one pair of the block opposing end faces is adjusted so as to satisfy 1<Ra(D)/Ra(S)≦12;
    A method for manufacturing a stacked core, wherein the pair of opposing end faces of the blocks are two opposing end faces of the blocks arranged in positions opposite to each other.
PCT/JP2023/035358 2022-10-03 2023-09-28 Stacked iron core and manufacturing method of stacked iron core WO2024075621A1 (en)

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JPH11124629A (en) * 1997-10-16 1999-05-11 Kawasaki Steel Corp Grain oriented silicon steel sheet reduced in iron loss and noise
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JPS6378509A (en) * 1986-09-20 1988-04-08 Mitsubishi Electric Corp Core for stationary induction apparatus
JPH11124629A (en) * 1997-10-16 1999-05-11 Kawasaki Steel Corp Grain oriented silicon steel sheet reduced in iron loss and noise
JP2002164225A (en) * 2000-11-28 2002-06-07 Nippon Steel Corp Low-noise electromagnetic steel sheet and laminated iron core
JP2007002334A (en) * 2005-05-09 2007-01-11 Nippon Steel Corp Low core loss grain-oriented electrical steel sheet and method for producing the same
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