WO2003011558A1 - Method for molding plastic magnet and magnetizing yoke used for it, and method for manufacturing magnet roller - Google Patents

Method for molding plastic magnet and magnetizing yoke used for it, and method for manufacturing magnet roller Download PDF

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Publication number
WO2003011558A1
WO2003011558A1 PCT/JP2002/007073 JP0207073W WO03011558A1 WO 2003011558 A1 WO2003011558 A1 WO 2003011558A1 JP 0207073 W JP0207073 W JP 0207073W WO 03011558 A1 WO03011558 A1 WO 03011558A1
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WO
WIPO (PCT)
Prior art keywords
magnet
magnetic
magnetic force
magnet roller
magnetic field
Prior art date
Application number
PCT/JP2002/007073
Other languages
French (fr)
Japanese (ja)
Inventor
Yuichi Hamaguchi
Taihei Goto
Original Assignee
Bridgestone Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2001387371A external-priority patent/JP2003188011A/en
Application filed by Bridgestone Corporation filed Critical Bridgestone Corporation
Publication of WO2003011558A1 publication Critical patent/WO2003011558A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0273—Imparting anisotropy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/0013—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor using fillers dispersed in the moulding material, e.g. metal particles
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
    • G03G15/0921—Details concerning the magnetic brush roller structure, e.g. magnet configuration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/1701—Component parts, details or accessories; Auxiliary operations using a particular environment during moulding, e.g. moisture-free or dust-free
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
    • B29K2105/20—Inserts
    • B29K2105/203—Magnetic parts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0003—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular electrical or magnetic properties, e.g. piezoelectric
    • B29K2995/0008—Magnetic or paramagnetic

Definitions

  • the present invention relates to a method of forming a magnet piece or other plastic magnet having a substantially fan-shaped cross section as a component of a magnet roller used as a developing roll of a copying machine or a printer, and a magnetizing method used for the same. And a method of manufacturing a magnet roller.
  • Electrophotographic devices such as copiers and printers ⁇
  • a magnet formed by a resin magnet inside a rotating sleeve is used as a development method to visualize an electrostatic latent image on a latent image holder such as a photosensitive drum.
  • a roller is provided, and the toner carried on the surface of the sleeve flies onto the latent image carrier by the magnetic characteristics of the magnet roller.
  • the toner is supplied to the surface of the latent image carrier by a jamming phenomenon, and an electrostatic latent image is formed.
  • Development methods for visualizing are known.
  • a resin material in which magnetic powder such as ferrite is mixed and dispersed in a binder of thermoplastic resin such as nylon or polypropylene is injected into the magnetic field of the mold cavity to have a fan-shaped cross section.
  • a method of manufacturing the magnet piece by adjoining the magnet pieces to each other in a circumferential direction around a shaft and combining them in a cylindrical shape is widely used.
  • FIG. 12 is a schematic cross-sectional view showing a magnet roller 90 formed in this manner.
  • This magnet roller 90 is composed of magnet pieces 92 and 94 having an N pole and a magnet having an S pole. It is formed by arranging the pieces 91, 93 circumferentially adjacent to each other around the shaft 95. Magnet opening formed in this way Has the following two problems.
  • the first problem is that when a circumferential magnetic force pattern of a magnet roller is given, this magnetic force pattern was conventionally realized by optimizing the cross-sectional shape of each magnet piece. It takes a long time for trial production and a lot of know-how to obtain the final shape, and in some cases, the required magnetic performance may not be sufficiently satisfied no matter how many trials are performed.
  • a magnetized yoke 85 is formed at a position corresponding to, for example, a substantially central portion of an arcuate surface 84 formed on the upper die 81 and defining the molded cavity 83, while defining the sector-shaped molded cavity 83.
  • the magnetic powder was mixed and dispersed in the molding cavity 83 formed with a magnetic field by the magnetizing yoke 85 when the tip end surface of the narrow protrusion was fixedly arranged on the upper die 81 close to the arcuate surface 84.
  • the required magnetic characteristics for the magnet roller 90 are as follows. For example, if the N pole is located on one side from the circumferential center of the outer peripheral surface of the magnet piece 92, the magnetizing yoke 8 By displacing 5 from the center of the arcuate surface 84 to one side, the magnetic pole position of the N pole can be formed accurately, but in this case, the circumferential magnetic force pattern there is Because of the large spacing, the shoulders Sh as shown in Fig. 14 are obtained, and the circumferential magnetic force pattern must be corrected or changed to a smooth pattern as shown in Fig. 15. Is required.
  • the magnet pieces 91 to 94 are formed by injection molding. Although the problem in the case of forming the magnet pieces has been described, there is a similar problem in the case where the magnet pieces 91 to 94 are extruded.
  • a resin material containing magnetic powder is extruded into a die opening where a magnetic field is formed by a magnetized yoke, and then cut into a predetermined length to form a magnet piece.
  • the cross-sectional view of the die and the die opening is similar to the cross-sectional view shown in FIG. 13, and the magnetizing yoke is located at a position corresponding to, for example, substantially the center of the arc-shaped surface that defines the die opening.
  • the magnetic powder By extruding the magnet piece, the magnetic powder can be concentrated and oriented at the portion of the magnet piece close to the magnetized yoke, and the magnetic pole can be formed there. Due to the location and shape, the circumferential magnetic pattern has a shoulder Sh, as in the case where it is formed by injection molding, and there is a problem that this magnetic pattern must be corrected. .
  • the circumferential magnetic force pattern is confirmed by cutting the side face of the sector-shaped magnet piece 92 and changing the sector shape, etc. While the final shape of the magnet piece 92 is specified, a molding die or an extrusion die is manufactured based on the final shape. The same applies to other magnet pieces. Conventionally, the final shapes of the magnet pieces 91 to 94 are specified through such a complicated process, and this leads to the first problem described above.
  • the second problem is that the magnet roller 90 made by combining the magnet pieces 91 to 94 does not have a uniform magnetic force distribution in the roller axis direction.
  • the process of measuring and grinding the magnetic force was required, and this required extra man-hours and capital investment.
  • the magnet roller 90 which is simply a combination of the magnet pieces 91 to 94, can obtain the desired circumferential magnetic force pattern at the axial center portion, but at the axial end portions.
  • the magnetic force is higher than the central part in the axial direction, a so-called shoulder-raising phenomenon occurs. Therefore, when such a magnet roller is used in a copying machine or the like, the expected performance at the axial end is obtained. Therefore, there is a problem that the image corresponding to the axial end portion becomes darker or lighter than the image corresponding to the central portion.
  • Fig. 16 is a graph illustrating the magnetic force distribution in the axial direction of the N pole of the magnet roller 90 of the magnet roller 90, where the horizontal axis represents the axial position and the vertical axis represents the axial position.
  • Pc indicates a point at the center of the magnet roller 90 in the axial direction
  • P1 and P2 indicate the axial ends of an effective portion where the magnetic force of the magnet roller is to function.
  • shoulder-up phenomenon occurs.
  • the axial end of the magnet roller 90 is formed in a predetermined procedure or according to the result of measuring the magnetic force.
  • the magnetic force must be adjusted by grinding a predetermined portion, which is the second problem described above.
  • the object of the present invention is to solve the first problem by forming a required circumferential magnetic force pattern, By changing the shape or structure of the magnetized yoke without changing the shape of the plastic magnet such as the magnet piece, it is possible to modify or change the circumferential magnetic force pattern compared to the conventional technology. It can be done in a short time without the need for know-how In order to provide a method for molding a plastic magnet and a magnetized yoke used for the same, which enable usual injection molding of the magnet,
  • the magnetic force at the axial end of the magnet roller formed by combining the magnet pieces in the circumferential direction can be formed substantially equal to the magnetic force at the axial center. Further, it is an object of the present invention to provide a method of manufacturing a magnet roller which does not require adjusting the magnetic force by forming a cylindrical magnet roller and then grinding the same.
  • the present invention has been made, and its gist configuration and operation will be described below.
  • the method for molding a plastic magnet of the present invention includes the steps of: injecting a resin material containing magnetic powder into a molding cavity in which a magnetic field is formed by a magnetized yoke; When extruding a resin material containing magnetic powder and molding a plastic magnet,
  • a strong magnetic field is formed at the molding cavity or die opening at the portion of the magnetized yoke closest to the molding cavity or die opening, and the magnetic field is formed at a predetermined region on at least one side of the region where the strong magnetic field is formed. It creates a relatively weak magnetic field in the cavity or die opening.
  • This molding method was made in response to the first problem described above.
  • a molten resin mixed with magnetic powder was injected into a molding cavity, or a magnetic field was formed by a magnetized yoke.
  • a magnetic pole can be formed in a plastic magnet formed by extruding a resin material containing magnetic powder into a die opening, by intensively orienting the magnetic powder in a portion having a strong magnetic field.
  • a shoulder Sh may be generated in the circumferential magnetic force pattern as illustrated in FIG. 14, and according to the method of the present invention, at least one side of a region where a strong magnetic field is formed.
  • a relatively weak magnetic field is formed in the molding cavity or in the die opening in the predetermined region of the mold, for example, in the region corresponding to the above-mentioned shoulder Sh, and the magnetic powder is slightly oriented in the weak magnetic field. Is performed, the shoulder Sh ′ in the circumferential magnetic force pattern as shown in FIG. 14 is substantially eliminated, and a smooth circumferential magnetic force pattern as shown in FIG. 15 is obtained. Can be.
  • the expected circumferential magnetic force pattern can be obtained without specifying the final shape of the plastic magnet, which involves a change in shape, etc., and manufacturing a molding die or die based on the final shape. It can be easily realized in a short time.
  • the magnetized yoke according to the present invention which is preferably used for carrying out the above method, is made of a magnetic material, and is disposed in close proximity to a molding cavity of a plastic magnet or a die opening.
  • a magnetic field is formed in the die opening, and at least one side of the molding cavity or the narrow projection located closest to the die opening in the cross section in the width direction of the magnetization yoke.
  • a retreating part is provided which tends to be separated from the molding cavity.
  • the term “prone” refers to the molding cavity or the shape of the die opening, the shape of the receding portion, etc., and the retracted portion partially approaches the molding cavity while moving away from the narrow projection. Such cases are also intended to be included in the above invention.
  • a strong magnetic field can be formed in the molding cavity or the die opening with a narrow protrusion, and a relatively weak magnetic field can be formed by the receding portion. It can be used in the implementation of the method described above to provide the same effects as described above.
  • the recessed portion provided on the narrow projection has a relationship between the required magnetic characteristics and the original magnetic characteristics without the recessed portion, as described in FIG. It can be used to eliminate the shoulder Sh as shown in the figure, or to artificially increase the magnetic force in the part where the shoulder is not originally formed. It can be done only on the side or on both sides.
  • the recessed portion is an inclined surface or one or a plurality of step-shaped recessed portions.
  • the magnetic field formed in the molding cavity or the die opening can be gradually weakened as the distance from the narrow projection increases. Also, when it is made into a step shape, it can be gradually reduced.
  • a plurality of rod-shaped magnet pieces made of a resin material in which a magnetic powder is mixed and dispersed in a resin binder are formed in a columnar shape on the outer periphery of the shaft, adjacent to each other in the circumferential direction.
  • the magnet pieces After magnetizing at least one of the magnet pieces so that the magnetic force at both ends in the axial direction is lower than the magnetic force at the central portion in the axial direction at least in a part in the circumferential direction, the magnet pieces are removed from the remaining magnet pieces. It is formed in combination with a piece.
  • a method of manufacturing a magnet roller according to the present invention has been made in response to the first problem described above.
  • the inventors In order to investigate the cause of the magnetic force rising at the end of the conventional magnet roller, the inventors have determined the axial magnetic force distribution of the magnet piece alone and the magnetic force of this magnet piece after being combined with the magnet roller. The distributions were compared. As a result, in the magnetic force distribution of the magnet piece alone, However, with the magnet roller after the magnet pieces were combined, it was found that the magnetic force at the end of this portion was even greater and the shoulder was raised.
  • the manufacturing method of the magnet roller according to the present invention is based on this newly obtained knowledge, and according to this manufacturing method, the magnetic force generated by ascending the end shoulder when combining the magnet pieces is generated.
  • the magnet piece is formed by lowering the magnetic force at the end in the axial direction compared to the central part in the axial direction by the amount of the increase, so when the magnet pieces are combined with each other,
  • the magnetic force at the axial end of the roll is almost equal to the magnetic force at the center of the roll, and a magnet roller having a uniform magnetic force distribution in the axial direction can be formed.
  • a step of grinding the magnet roller after forming the magnet roller is not required, and the magnet roller can be manufactured simply and at low cost.
  • the method of manufacturing a magnet roller according to the present invention wherein in the invention described in (4), among the plurality of magnetic poles, at least one pair of repulsive poles which are adjacent to each other and have the same polarity is provided.
  • a magnetic roller used in a copying machine or the like at least one set of repulsive poles adjacent to each other is disposed among a plurality of magnetic poles disposed on the periphery of the magnet roller in order to improve a toner recovery rate.
  • a magnet roller having a zero gauss band with almost zero magnetic force and a flat magnetic force distribution in the circumferential direction is used.
  • such a zero Gaussian band has a small strength of its own magnetic field, and is affected by repulsion poles located on both sides in the circumferential direction, and its magnetic force distribution tends to be unstable.
  • the magnetic force at the axial end is affected by the discontinuity at the end As a result, it became more unstable, and it was more difficult to suppress the phenomenon of magnetic force rising at the end than in normal magnetic poles.
  • the magnet pieces including the zero Gauss band are magnetized so that the magnetic force at both ends in the axial direction of the magnet piece combined adjacently between the repulsion poles is lower than the magnetic force at the central portion in the axial direction.
  • the magnetic force in the axial direction can be made uniform by the shoulder magnetic force of the end portion, so that a particularly advantageous effect can be brought about.
  • a magnetizing yoke for magnetizing the inner peripheral surface to the polarity opposite to the repulsion pole is arranged at a position facing the inner peripheral surface side of the magnet piece, and these magnets are placed at opposing positions on both the side surfaces.
  • the method of manufacturing this magnet roller relates to a zero gauss band, in which it is particularly difficult to form a magnetic force.
  • a magnetic pole having a polarity opposite to that of the repulsion pole is formed on the inner peripheral surface of the shaft. After forming a magnetic pole having the same polarity as the repelling pole on the side, the magnet piece is demagnetized, and then the inner circumferential surface of the magnet piece is opposite in polarity to the repelling pole at the opposing position on the inner circumferential surface side of the magnet piece.
  • a magnetizing yoke that magnetizes these magnets is arranged, and magnetizing yokes that magnetize these sides to the same polarity as the repulsion poles are arranged at opposite positions on both sides of the magnet. From both sides to the inner circumference By thus forming a strongly oriented magnet, the number of lines of magnetic force directed outward from the outer peripheral surface of the magnet piece can be suppressed, and the magnetic force in the zero gauss band can be reduced to almost zero.
  • the magnet roller after the magnet piece is demagnetized, in addition to the above-described magnetized yokes arranged on the inner circumferential surface and both side surfaces of the magnet piece, the opposing positions of the axially opposite end portions on the outer circumferential surface side are further reduced.
  • a magnetizing yoke that applies a magnetic force of the opposite polarity to the zero Gaussian band is also arranged at both ends of the magnet piece so that the magnetic force at both ends in the axial direction of this magnet piece is lower than the magnetic force at the central part in the axial direction. Since it is magnetized, as described above, after it is combined with a cylindrical magnet roller, a magnet roller having a uniform magnetic distribution in the axial direction in the zero Gauss band can be formed.
  • the method of manufacturing a magnet roller according to the present invention is characterized in that, in the invention described in (6), the magnetized shock arranged at a position opposite to both axial ends on the outer peripheral surface side of the magnet piece is positioned from a central portion in the axial direction. It is arranged to be inclined so that it gets closer to the peripheral surface of the magnet piece as it goes away.
  • the magnetized yoke which is disposed at a position opposed to both ends in the axial direction on the outer peripheral surface side of the magnet piece, is moved closer to the peripheral surface of the magnet piece as the distance from the axial center increases. Since the magnet pieces are arranged at an inclination, a magnetic force distribution in which the magnetic force decreases smoothly from the center in the axial direction toward the end can be formed in the zero gauss band of the magnet piece. Since it works to cancel the edge rise when it is combined with the magnet roller, it works to cancel the edges, so the zero Gaussian band with uniform magnetic force distribution from the axial center to the end in the state after the magnet piece is combined It is possible to form a magnet roller having the following.
  • FIG. 1 is a longitudinal sectional view showing an application example of a magnetized yoke.
  • FIG. 2 is a cross-sectional view of a main part illustrating a mold apparatus used for injection molding.
  • FIG. 3 is a longitudinal sectional view showing another embodiment of the magnetization yoke.
  • FIG. 4 is a diagram showing a modified example of the retreat portion.
  • FIG. 5 is a schematic sectional view showing a magnet roller.
  • FIG. 6 is a magnetic force pattern diagram of the magnet roller.
  • FIG. 7 is a graph showing the magnetic force distribution of the magnet piece in the zero Gauss band.
  • FIG. 8 is a graph showing the magnetic force distribution of the magnet roller in the zero Gauss band.
  • FIG. 9 is a cross-sectional view showing the magnetization orientation of the magnet piece.
  • FIG. 10 is a side view showing the arrangement of the magnetization yoke.
  • FIG. 11 is a sectional view taken along the line XI-XI of FIG.
  • FIG. 12 is a sectional view of a magnet roller manufactured by a conventional method.
  • FIG. 13 is a longitudinal sectional view of a molding die using a conventional magnetized yoke.
  • FIG. 14 is a diagram illustrating a circumferential magnetic force pattern of a conventional magnet roller.
  • FIG. 15 is a diagram illustrating a circumferential magnetic force pattern after correction.
  • Figure 16 is a graph showing the magnetic force distribution of the N pole of a magnet roller manufactured by a conventional method.
  • Fig. 17 is a graph showing the magnetic force distribution in the zero gauss band of a magnet piece magnetized by a conventional method.
  • FIG. 1 is a longitudinal sectional view of a molding die showing an application example of a magnetized yoke according to the present invention.
  • 1 shows an upper die
  • 2 shows a lower die
  • 3 shows a shape between the upper and lower dies. It shows a molded cavity that has a substantially sectorial cross-section.
  • the magnetized yoke 4 is fixedly arranged on the upper mold 1, and the distal end face of the narrow projection 5 of the magnetized yoke 4 corresponds to the center of the upper mold arc surface 6 that defines the molding cavity 3.
  • the magnetized yoke 4 is provided with an inclined surface-like recessed portion 7 that is gradually separated from the molding cavity 3 as the angle increases.
  • such a magnetized yoke 4 is surrounded by a non-magnetic material 8, and the upper surface thereof is backed up by a magnetic material 9 and attached to the upper mold 1, and the molding cavity 3 is also formed.
  • the recessed portion 10 of the lower mold 2 to be partitioned is formed in the magnetic material 11.
  • the above-described molding die 12 is made into a mold device 13 as a set of four parts, and is subjected to injection molding.
  • the magnetized yoke 4 of each mold 12 forms a magnetic field in the molding cavity 3 based on the energization of the magnetized coil 14 disposed around the device 13, and is not shown.
  • the molten resin material containing the magnetic powder injected from the injection nozzle is pressure-filled into the molding cavity 3 from a sprue 15 through a runner 16 and a gate (not shown).
  • the resin material filled in the molding cavity 3 in this manner has a strong magnetic field in a region corresponding to the high-density magnetized yoke 4 and the narrow projections 5 as indicated by broken lines in FIG. From this, the magnetic powder is concentrated and oriented in that region, and a magnetic pole is provided there. On the other hand, in the region 17 corresponding to the receding portion 7, some orientation of the magnetic powder is performed based on the fact that the resin material is affected by the relatively weak magnetic field. Due to these facts, when a conventional magnetized yoke 85 without the retreat portion 7 is used, a circumferential magnetic force pattern with a shoulder Sh is obtained as shown in FIG. In the magnetized yoke 4 according to the present invention provided with 7, the circumferential magnetic force pattern as shown in FIG. 15 can be easily realized.
  • a recessed portion similar to or different in shape from the previous case may be provided on the right side of the narrow protrusion 5. According to this, the magnetic force on the opposite side of the peak in the circumferential magnetic force pattern is Can be increased.
  • FIG. 3 is a cross-sectional view showing another form of the magnetized yoke.
  • the magnetized yoke is formed so as to be biased to one side of the magnet piece to be formed, that is, to the right side in the figure, and to have a circumferential magnetic force.
  • a recessed portion 7 with an inclined surface that is wider than in the previous case is provided on the left side of the narrow protrusion 5. .
  • the intended purpose can be achieved by forming a weak magnetic field in the corresponding region 17 under the action of the receding portion 7 to bring the orientation of the magnetic powder there.
  • FIG. 4 is a diagram showing a modified example of the retreating portion of the magnetized yoke
  • FIG. 4a is a diagram in which the retreating portion 7 is formed into an inclined surface directly continuing to the distal end surface of the narrow projection 5. 1 and 3, this corresponds to a case where the step-down portion in the direction away from the molding cavity 3 is omitted.
  • FIG. 4B shows the retreating portion 7 in the form of a single horizontal plane stepping down from the distal end surface of the narrow projection 5.
  • the strength of the magnetic field formed in the receding portion 7 can be selected as required.
  • FIG. 5 is a schematic cross-sectional view showing a cross section of the magnet roller 21 according to the present invention.
  • the magnet roller 21 is formed by combining six rod-shaped magnet pieces 31 to 36 adjacent to each other in the circumferential direction around the shaft 22. These magnet pieces 31 to 36 are respectively , Which have N 1 to N 3 poles, S 1 pole, S 2 pole magnetic poles, and zero Gaussian band NO. here,
  • the N1 to N3 poles are magnetic poles having the polarity of N
  • the S1 to S2 poles are magnetic poles having the polarity of S. Of these, N2 and N3 are repulsive poles forming a pair.
  • FIG. 6 is a graph showing a circumferential magnetic force pattern obtained by measuring the magnetic force on the circumferential surface of the magnet roller 21.
  • the horizontal axis represents the circumferential position by an angle, and the vertical axis represents the magnitude of the magnetic force.
  • the magnet roller 21 has a zero Gaussian band between the pair of repulsive poles N 2 and N 3 having a magnetic force distribution of N and a magnetic force distribution which spreads flat in the circumferential direction while the magnetic force is almost zero. .
  • FIG. 7 is a graph showing the magnetic distribution in the axial direction of the zero Gaussian band N 0 in the magnet piece 36 before being combined with the magnetic roller 21.
  • the horizontal axis represents the axial position, and the vertical axis represents the magnetic force. Indicates the size.
  • the range of P1 to P2 is the effective range of the magnetic force when the magnet roller 1 is mounted on the apparatus. In the method of manufacturing the magnet roller, when magnetizing the magnet piece 36, P1 and P2 are used.
  • the magnetic force at the axial position near the end near 2 is formed to be smaller than the magnetic force at the center in the axial direction, and the magnetic force becomes smaller toward the end.
  • FIG 8 is a graph showing the axial magnetic force distribution of the zero Gaussian band NO after forming the magnet roller 21 by combining the magnet piece 36 with the other magnet pieces 31 to 35.
  • the magnetometer shows that it is possible to distribute the magnetic force in the zero Gaussian band NO uniformly in the axial direction and to control the magnetic force to be almost zero. ing.
  • the magnetic force at the end of the magnet piece 36 before being combined with the magnet roller 21 in the zero-gauss band is smaller than that in the center. It is important to keep this in mind, and this can be achieved by the following method.
  • FIG. 6 is a cross-sectional view showing the orientation of the magnetic powder in the cross section of FIG. 6, wherein the orientation of the magnetic powder is such that the inner peripheral surface 41 side of the magnet piece 36 is an S pole, and both side surfaces 42 are N poles.
  • an AC magnetic field is applied to the magnet piece 36 to demagnetize it once, and a magnetizing yoke is arranged around the magnet piece 36 to magnetize the piece 36.
  • FIG. 10 is a side view showing the arrangement of the magnetized yokes
  • FIG. 11 is a cross-sectional view showing a XI-XI cross section of FIG.
  • a magnetized yoke 51 of polarity N is arranged facing the inner peripheral surface 41 of the magnet piece 36, and a magnetized yoke 52 of polarity S is arranged facing both sides 22.
  • the inner peripheral surface 41 is magnetized to the S pole, and both side surfaces 42 are magnetized to the N pole.
  • the magnetizing yokes 53 with N polarity on both ends of the outer peripheral surface 43 of the magnet piece 36, the end of the cellogauss band NO originally oriented slightly toward the N pole Demagnetize the magnetic force. Further, the magnetizing yoke 53 is gradually inclined from the axial center to the end of the magnet piece 36 so as to approach the outer peripheral surface 43 of the magnet piece 36. A nonmagnetic spacer 54 having a triangular cross section is provided between the outer peripheral surface 43 of the magnet piece 36 and the magnetized yoke 53.
  • the magnetic force distribution at the axial end is lower than the magnetic force at the center as shown in Fig. 3.
  • the magnet piece 36 having the zero Gaussian band NO can be formed.
  • the magnet piece 36 will have an axial magnetic force distribution as shown in FIG.
  • the magnetic force at the end in the axial direction is further emphasized and the shoulder rises, which is an improvement over what could not be used for practical use.
  • the magnet piece 36 molded in a magnetic field was temporarily erased. After magnetizing, re-magnetization was performed. Even if re-magnetization is performed without degaussing, the same effect can be obtained depending on the magnetizing conditions. Further, in this embodiment, the magnet piece 36 having a zero Gaussian band has been described. However, apart from the magnitude of the effect, these are incorporated into the magnet roller for other magnet pieces 31 to 35 as well. By reducing the magnetic force at the axial end portion from the magnetic force at the central portion in the previous state, the axial magnetic force distribution after combination with the magnet roller can be made more uniform.
  • the resin material mixed with the magnetic powder is injected into a mold to which a magnetic field is applied to form a magnet piece 36, which is then demagnetized, and then magnetized as shown in Figs. 10 and 11.
  • the magnet pieces 36 are re-magnetized by placing the magnets 51 to 53, and the pieces 36 are incorporated into the magnet roller 21 manufactured to have a cross section shown in FIG.
  • the magnetic force distribution in the axial direction of the zero Gaussian band NO of the magnet roller 21 of this embodiment was measured, and the magnet piece 36 was mounted without the magnetized yoke 53 of the magnetized yokes shown in FIG. It was compared with the magnetic force distribution of a conventional magnet roller formed by magnetizing.
  • the method of manufacturing the magnet roller of the conventional example is exactly the same as the method of manufacturing the magnet roller of the embodiment except that the magnetizing yoke 53 is not provided.
  • the outer diameter of the magnet roller used in this comparison is 14.5 mm.
  • the outer diameter of the sleeve arranged on the outer periphery of the magnet roller is 16 mm. Therefore, when measuring the magnetic force of the magnet roller, the tip of the measurement probe is separated from the axis of the magnet roller by 8 mm. It was placed at the position.
  • Table 1 shows the measurement results of the magnetic force distribution in the axial direction of the zero-us band of the magnet roller of the embodiment and the conventional example, and the minimum value from the maximum value of the end magnetic force and the maximum magnetic force in the effective range of the axial magnetic force, respectively. It is shown by magnetic force variation from which magnetic force is subtracted.
  • the maximum value of the magnetic force at the end of the magnet roller and the variation in magnetic force are 4 mT, It is 3 mT, and Table 1 shows that the magnetic force distribution in the zero gauss band, which is not allowed by the conventional magnet roller, has been improved to an acceptable level by the magnet roller manufactured by the manufacturing method of the embodiment.
  • a strong magnetic field is formed in the molding cavity, particularly at the portion of the magnetization yoke closest to the molding cavity.
  • the circumferential magnetic force pattern of the plastic magnet can be adjusted as required. Modifications or changes can be easily achieved in a short time without requiring much know-how as in the prior art, and also enable constant injection molding of plastic magnets. Can be.
  • the magnet piece is magnetized so that the magnetic force at both ends in the axial direction is lower than the magnetic force at the central portion in the axial direction at least in a part in the circumferential direction. Since the magnet roller is manufactured by combining this magnet piece with the remaining magnet pieces, it is possible to manufacture the entire magnet roller having a uniform magnetic force distribution in the axial direction without adjusting the magnetic force.

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Abstract

For molding a plastic magnet by injecting a resin material mixed with a compounded magnetic powder into a molding cavity (3) wherein a magnetic field is produced by a magnetizing yoke (4), a strong magnetic field is produced in the molding cavity (3) by a narrow-width projection (5) of the magnetizing yoke (4), and a relatively weak magnetic field is produced by a recessed part (7) in a predetermined region on one side of this strong magnetic field region. Thus, a required circumferential magnetic force pattern for the plastic magnet is realized in a short time without needing many know-hows. Especially, when manufacturing a magnet roller by combining magnet pieces, the magnetic force produced at an axial end of the magnet roller is almost equal to that at the center part. Thus, a method for manufacturing a magnet roller which dispenses with the adjustment of a magnetic force by grinding a formed magnet roller.

Description

明 細 書 プラスチックマグネッ卜の成形方法およびそれに用いる着磁ヨーク、 ならびにマ グネットローラの製造方法  Description Molding method of plastic magnet, magnetized yoke used therefor, and method of manufacturing magnet roller
技術分野 Technical field
この発明は、 たとえば、 複写機、 プリンタの現像用ロール等として用いられる マグネットローラの構成部品としての、 断面形状がほぼ扇形等をなすマグネット ピースその他のプラスチックマグネットの成形方法およびそれに用いる着磁ョ一 クならびにマグネットローラの製造方法に関する。  The present invention relates to a method of forming a magnet piece or other plastic magnet having a substantially fan-shaped cross section as a component of a magnet roller used as a developing roll of a copying machine or a printer, and a magnetizing method used for the same. And a method of manufacturing a magnet roller.
背景技術 Background art
複写機、 プリンタ等の電子写真装置ゃ静電記録装置などにおいて、 感光ドラム 等の潜像保持体上の静電潜像を可視化する現像方式として、 回転するスリーブ内 に樹脂磁石により形成されたマグネットローラを配設し、 スリーブ表面に担持し たトナーをマグネットローラの磁力特性により潜像保持体上に飛翔させる、 ジャ ンビング現象によって、 潜像保持体表面にトナーを供給し、 静電潜像を可視化す る現像方法が知られている。  Electrophotographic devices such as copiers and printers ゃ In electrostatic recording devices, etc., a magnet formed by a resin magnet inside a rotating sleeve is used as a development method to visualize an electrostatic latent image on a latent image holder such as a photosensitive drum. A roller is provided, and the toner carried on the surface of the sleeve flies onto the latent image carrier by the magnetic characteristics of the magnet roller.The toner is supplied to the surface of the latent image carrier by a jamming phenomenon, and an electrostatic latent image is formed. Development methods for visualizing are known.
そのマグネットローラを製造するに際しては、 ナイロンやポリプロピレン等の 熱可塑性樹脂のバインダにフェライト等の磁性粉体を混合分散した樹脂材料を金 型のキヤビティの磁場内に射出して、 扇形の断面を持つ棒状のマグネットピース を形成した後、 これらのマグネットピースを、 シャフトの周りに周方向に互いに 隣接させ、 円柱状に組み合わせて製造する方法が、 広く行われている。  When manufacturing the magnet roller, a resin material in which magnetic powder such as ferrite is mixed and dispersed in a binder of thermoplastic resin such as nylon or polypropylene is injected into the magnetic field of the mold cavity to have a fan-shaped cross section. After a rod-shaped magnet piece is formed, a method of manufacturing the magnet piece by adjoining the magnet pieces to each other in a circumferential direction around a shaft and combining them in a cylindrical shape is widely used.
図 1 2は、 このようにしてできるマグネッ卜ローラ 9 0を示す略線断面図であ り、 このマグネットローラ 9 0は、 N極を有するマグネットピース 9 2、 9 4お よび S極を有するマグネットピース 9 1、 9 3をシャフト 9 5の回りに周方向に 互いに隣接させて配置して形成される。 このようにして形成されるマグネット口 ーラは、 以下のような二つの問題点をかかえている。 FIG. 12 is a schematic cross-sectional view showing a magnet roller 90 formed in this manner. This magnet roller 90 is composed of magnet pieces 92 and 94 having an N pole and a magnet having an S pole. It is formed by arranging the pieces 91, 93 circumferentially adjacent to each other around the shaft 95. Magnet opening formed in this way Has the following two problems.
第一の問題点は、 マグネットローラの周方向磁力パターンが与えられたとき、 従来はそれぞれのマグネットピースの断面形状を最適化することによりこの磁力 パターンを実現していたので、 最適なマグネットピースの最終形状を得るまでに 長時間の試作と多くのノウハウを要し、 場合によっては、 試作を何度行っても所 要の磁力性能を十分満足させられないことがあるという点である。  The first problem is that when a circumferential magnetic force pattern of a magnet roller is given, this magnetic force pattern was conventionally realized by optimizing the cross-sectional shape of each magnet piece. It takes a long time for trial production and a lot of know-how to obtain the final shape, and in some cases, the required magnetic performance may not be sufficiently satisfied no matter how many trials are performed.
従来、 マグネットピースを成形する際、 たとえば図 1 3に成形金型の要部縦断 面図を磁束線とともに例示するように、 上型 8 1と下型 8 2との間に、 断面形状 がほぼ扇形をなす成形キヤビティ 8 3を区画するとともに、 上型 8 1に形成され て成形キヤビティ 8 3を区画する弧状面 8 4のたとえばほぼ中央部と対応する位 置で、 着磁ヨーク 8 5を、 その狭幅突部先端面を弧状面 8 4に近接させて上型 8 1に固定配置したところにおいて、 着磁ヨーク 8 5によって磁場を形成した成形 キヤビティ 8 3内へ、 磁性粉を混合分散した樹脂材料を射出するものがあり、 こ れによれば、 マグネットピースの、 着磁ヨーク 8 5に近接した部分で磁性粉を集 中配向させてそこに磁極を形成することができる。  Conventionally, when forming a magnet piece, the cross-sectional shape between the upper die 81 and the lower die 82 is almost the same, for example, as shown in FIG. A magnetized yoke 85 is formed at a position corresponding to, for example, a substantially central portion of an arcuate surface 84 formed on the upper die 81 and defining the molded cavity 83, while defining the sector-shaped molded cavity 83. The magnetic powder was mixed and dispersed in the molding cavity 83 formed with a magnetic field by the magnetizing yoke 85 when the tip end surface of the narrow protrusion was fixedly arranged on the upper die 81 close to the arcuate surface 84. There is a type that injects a resin material. According to this, the magnetic powder can be centrally oriented at a portion of the magnet piece close to the magnetizing yoke 85, and a magnetic pole can be formed there.
ところで、 このようにして成形した複数のマグネットピース 9 1〜9 4を貼り 合わせて、 図 1 2に示すようなマグネッ卜ローラ 9 0を構成したところにおいて、 マグネットローラ 9 0に対する要求磁気特性が、 たとえば、 N極がマグネットピ ース 9 2の外周面の周方向中央部から一方側へ偏って位置するものである場合に は、 N極の周方向の偏りに対応させて、 着磁ヨーク 8 5を弧状面 8 4の中央部か ら一方側に偏らせて配置することにより、 N極の磁極位置を正確に形成すること ができるが、 この場合、 そこでの周方向磁力パターンは、 磁極間の間隔が広いた め、 図 1 4に例示するような肩部 S hを有するものとなってしまい、 その周方向 磁力パターンを、 図 1 5に示すような滑らかなパターンに修正ないしは変更する ことが必要になる。  By the way, when a plurality of magnet pieces 91 to 94 molded in this manner are bonded together to form a magnet roller 90 as shown in FIG. 12, the required magnetic characteristics for the magnet roller 90 are as follows. For example, if the N pole is located on one side from the circumferential center of the outer peripheral surface of the magnet piece 92, the magnetizing yoke 8 By displacing 5 from the center of the arcuate surface 84 to one side, the magnetic pole position of the N pole can be formed accurately, but in this case, the circumferential magnetic force pattern there is Because of the large spacing, the shoulders Sh as shown in Fig. 14 are obtained, and the circumferential magnetic force pattern must be corrected or changed to a smooth pattern as shown in Fig. 15. Is required.
なお、 以上の説明において、 マグネットピース 9 1〜9 4を射出成形により形 成する場合についての問題点を説明したが、 マグネットピース 9 1〜 9 4を押出 成形する場合にも同様の問題点がある。 In the above description, the magnet pieces 91 to 94 are formed by injection molding. Although the problem in the case of forming the magnet pieces has been described, there is a similar problem in the case where the magnet pieces 91 to 94 are extruded.
すなわち、 押出成形の場合、 着磁ヨークによって磁場を形成したダイ開口部に、 磁性粉を配合した樹脂材料を押出したあと、 これを所定の長さに切断してマグネ ットピースを形成するが、 このダイおよびダイ開口部の断面図は、 図 1 3に示す 断面図と類似のものとなっていて、 ダイ開口部を区画する弧状面のたとえばほぼ 中央部と対応する位置で、 着磁ヨークを、 その狭幅突部先端面をこの弧状面に近 接させてダイに固定配置したところにおいて、 着磁ヨークによって磁場を形成し たダイ開口部内に、 磁性粉を混合分散した樹脂材料を通過させてマグネットピ一 スを押出成形することにより、 マグネットピースの、 着磁ヨークに近接した部分 で磁性粉を集中配向させてそこに磁極を形成することができるが、 その着磁ョー クの配置と形状ゆえに、 これを射出成形にて形成した場合と同様、 その周方向磁 力パターンは肩部 S hを有するものとなってしまい、 この磁力パターンを修正し なければならないという問題点がある。  That is, in the case of extrusion molding, a resin material containing magnetic powder is extruded into a die opening where a magnetic field is formed by a magnetized yoke, and then cut into a predetermined length to form a magnet piece. The cross-sectional view of the die and the die opening is similar to the cross-sectional view shown in FIG. 13, and the magnetizing yoke is located at a position corresponding to, for example, substantially the center of the arc-shaped surface that defines the die opening. When the tip surface of the narrow projection is fixed to the die so as to be close to this arcuate surface, the resin material mixed and dispersed with magnetic powder is passed through the die opening where the magnetic field is formed by the magnetization yoke. By extruding the magnet piece, the magnetic powder can be concentrated and oriented at the portion of the magnet piece close to the magnetized yoke, and the magnetic pole can be formed there. Due to the location and shape, the circumferential magnetic pattern has a shoulder Sh, as in the case where it is formed by injection molding, and there is a problem that this magnetic pattern must be corrected. .
そこで、 マグネットローラの試作段階でこのような周方向磁力パターンが生じ た場合には、 扇形をなすマグネットピース 9 2の側面を削って扇形形状に変更を 加える等して、 周方向磁力パターンを確認しながらマグネットピース 9 2の最終 形状を特定し、 この最終形状をもとに成形金型もしくは押出ダイを製作すること となる。 他のマグネットピースについても同様であり、 従来はこのような複雑な 過程を経てマグネットピース 9 1〜 9 4の最終形状が特定され、 これが前述の第 一の問題点をもたらすこととなる。  Therefore, if such a circumferential magnetic force pattern occurs during the prototype stage of the magnet roller, the circumferential magnetic force pattern is confirmed by cutting the side face of the sector-shaped magnet piece 92 and changing the sector shape, etc. While the final shape of the magnet piece 92 is specified, a molding die or an extrusion die is manufactured based on the final shape. The same applies to other magnet pieces. Conventionally, the final shapes of the magnet pieces 91 to 94 are specified through such a complicated process, and this leads to the first problem described above.
第二の問題点は、 マグネットピース 9 1〜 9 4を組み合わせてできたマグネッ トロ一ラ 9 0はローラ軸方向の磁力分布が均一ではなく、 この磁力分布を均一に するためマグネットローラ 9 0の磁力を測定したりこれを研削したりする作業等 の工程が必要となり、 このための余計な工数と設備投資が発生していたという点 である。 すなわち、 従来、 単にマグネットピース 9 1〜9 4を組み合わせたできたマグ ネットローラ 9 0は、 その軸方向中央部分では、 所期した周方向の磁力パターン を得ることができるものの、 軸方向両端部においては、 磁力が、 軸方向中央部分 より高くなる、 いわゆる肩上がり現象が起こり、 このため、 このようなマグネッ トローラを複写機等に用いた場合には、 軸方向端部で所期したその性能を発揮す ることができず、 軸方向端部に対応する部分の画像が、 中央部に対応する画像よ り濃くなつたり薄くなつたりするという問題があった。 The second problem is that the magnet roller 90 made by combining the magnet pieces 91 to 94 does not have a uniform magnetic force distribution in the roller axis direction. The process of measuring and grinding the magnetic force was required, and this required extra man-hours and capital investment. In other words, conventionally, the magnet roller 90, which is simply a combination of the magnet pieces 91 to 94, can obtain the desired circumferential magnetic force pattern at the axial center portion, but at the axial end portions. In this case, the magnetic force is higher than the central part in the axial direction, a so-called shoulder-raising phenomenon occurs. Therefore, when such a magnet roller is used in a copying machine or the like, the expected performance at the axial end is obtained. Therefore, there is a problem that the image corresponding to the axial end portion becomes darker or lighter than the image corresponding to the central portion.
図 1 6は、 マグネットローラ 9 0の、 マグネットピース 9 2にある N極の軸方 向の磁力分布を例示するグラフであり、 横軸はその軸方向の位置を、 縦軸は各軸 方向位置での磁力を示し、 P cはこのマグネットローラ 9 0の軸方向の中心の点 を示し、 マグネットローラの磁力を機能させるべき有効部分の軸方向両端部を、 それぞれ、 P 1および P 2で示す。 P 1および P 2の間に位置し、 これらの点の 近傍の端部付近では、 その磁力が中央部に比して高くなる、 いわゆる肩上がり現 象が生じる。 そして、 この肩上がり現象を有するマグネットローラ 9 0を複写機 等の装置に搭載して用いた場合、 マグネットローラ 9 0のこの肩上がり部分に対 応する画像の端が画像不良を引起す可能性を持つことになるわけである。  Fig. 16 is a graph illustrating the magnetic force distribution in the axial direction of the N pole of the magnet roller 90 of the magnet roller 90, where the horizontal axis represents the axial position and the vertical axis represents the axial position. , Pc indicates a point at the center of the magnet roller 90 in the axial direction, and P1 and P2 indicate the axial ends of an effective portion where the magnetic force of the magnet roller is to function. . Located between P1 and P2, near the ends near these points, the magnetic force is higher than at the center, a so-called shoulder-up phenomenon occurs. When the magnet roller 90 having the rising phenomenon is mounted on a copying machine or the like and used, the edge of the image corresponding to the rising portion of the magnet roller 90 may cause an image defect. That is to have.
この問題に対処するため、 従来は、 マグネットローラ 9 0を円柱状に形成した 後、 予め定められた手順で、 もしくは、 磁力を測定した結果に合わせて、 マグネ ットローラ 9 0の軸方向端部の所定部分を研削加工することにより磁力調整を行 わざるを得ず、 これが前述の第二の問題点である。  To cope with this problem, conventionally, after forming the magnet roller 90 in a cylindrical shape, the axial end of the magnet roller 90 is formed in a predetermined procedure or according to the result of measuring the magnetic force. The magnetic force must be adjusted by grinding a predetermined portion, which is the second problem described above.
この発明は、 従来技術が抱えるこれらの問題点を解決することを課題とするも のであり、 それの目的とするところは、 第一の問題点に対応して、 所要の周方向 磁力パターンを、 マグネットピース等のプラスチックマグネットの形状等はその ままに、 とくには、 着磁ヨークの形状ないしは構造の変更によって実現すること で、 従来技術に比し、 周方向磁力パターンの修正ないしは変更を、 多くのノウハ ゥを必要とすることなく短時間のうちに行うことができ、 しかも、 プラスチック マグネッ卜の常なる射出成形を可能としたプラスチックマグネッ卜の成形方法お よびそれに用いる着磁ヨークを提供することにあり、 It is an object of the present invention to solve these problems of the prior art. The object of the present invention is to solve the first problem by forming a required circumferential magnetic force pattern, By changing the shape or structure of the magnetized yoke without changing the shape of the plastic magnet such as the magnet piece, it is possible to modify or change the circumferential magnetic force pattern compared to the conventional technology. It can be done in a short time without the need for know-how In order to provide a method for molding a plastic magnet and a magnetized yoke used for the same, which enable usual injection molding of the magnet,
また、 第二の問題点に対応して、 マグネットピースを周方向に組み合わせて形 成されるマグネットローラの軸方向端部の磁力を、 軸方向中央部の磁力とほぼ等 しく形成することができ、 しかも、 円柱状のマグネットローラを形成したあとこ れを研削等して磁力調整する必要のないマグネットローラの製造方法を提供する ことにある。  Also, in response to the second problem, the magnetic force at the axial end of the magnet roller formed by combining the magnet pieces in the circumferential direction can be formed substantially equal to the magnetic force at the axial center. Further, it is an object of the present invention to provide a method of manufacturing a magnet roller which does not require adjusting the magnetic force by forming a cylindrical magnet roller and then grinding the same.
発明の開示 Disclosure of the invention
上記目的を達成するため、 この発明はなされたものであり、 その要旨構成なら びに作用を以下に示す。  To achieve the above object, the present invention has been made, and its gist configuration and operation will be described below.
( 1 )  (1)
本発明のプラスチックマグネットの成形方法は、 着磁ヨークによって磁場を形 成した成形キヤビティ内へ、 磁性粉を配合した樹脂材料を射出して、 もしくは、 着磁ヨークによって磁場を形成したダイ開口部に磁性粉を配合した樹脂材料を押 出して、 プラスチックマグネットを成形するに当り、  The method for molding a plastic magnet of the present invention includes the steps of: injecting a resin material containing magnetic powder into a molding cavity in which a magnetic field is formed by a magnetized yoke; When extruding a resin material containing magnetic powder and molding a plastic magnet,
着磁ヨークの、 成形キヤビティもしくはダイ開口部に最も近接する部分で、 そ の成形キヤビティもしくはダイ開口部に強い磁場を形成するとともに、 この強い 磁場の形成域の少なくとも一方側の所定領域で、 成形キヤビティ内もしくはダイ 開口部内に、 相対的に弱い磁場を形成するものである。  A strong magnetic field is formed at the molding cavity or die opening at the portion of the magnetized yoke closest to the molding cavity or die opening, and the magnetic field is formed at a predetermined region on at least one side of the region where the strong magnetic field is formed. It creates a relatively weak magnetic field in the cavity or die opening.
この成形方法は、 前述の第一の問題点に対応してなされたものであり、 磁性粉 を配合した溶融榭脂材料を成形キヤビティ内へ射出して、 もしくは、 着磁ヨーク によって磁場を形成したダイ開口部に磁性粉を配合した樹脂材料を押出して形成 されるプラスチックマグネッ卜に、 磁場の強い部分で磁性粉を集中配向させてそ こに磁極を形成することができる。  This molding method was made in response to the first problem described above. A molten resin mixed with magnetic powder was injected into a molding cavity, or a magnetic field was formed by a magnetized yoke. A magnetic pole can be formed in a plastic magnet formed by extruding a resin material containing magnetic powder into a die opening, by intensively orienting the magnetic powder in a portion having a strong magnetic field.
しかも、 この成形方法によれば、 次のようなきわだった作用効果をもたらすこ とができる。 すなわち、 キヤビティ内もしくはダイ開口部内への強い磁場だけで マグネットピースを形成する場合には、 周方向磁力パターンに、 図 1 4に例示す るような肩部 S hが発生することがあり、 この発明の方法に従って、 強い磁場の 形成域の少なくとも一方側の所定領域、 たとえば、 上記肩部 S hと対応する領域 で、 成形キヤビティ内もしくはダイ開口部内に、 相対的に弱い磁場を形成し、 こ の磁場の弱い部分にて磁性粉に幾分の配向を行わせることにより、 周方向磁力パ ターンにおける、 図 1 4に示すような肩部 S h'を実質的に消去して、 図 1 5に示 すような滑らかな周方向磁力パターンをもたらすことができる。 Moreover, according to this molding method, the following distinctive effects can be obtained. That is, only the strong magnetic field in the cavity or die opening When a magnet piece is formed, a shoulder Sh may be generated in the circumferential magnetic force pattern as illustrated in FIG. 14, and according to the method of the present invention, at least one side of a region where a strong magnetic field is formed. A relatively weak magnetic field is formed in the molding cavity or in the die opening in the predetermined region of the mold, for example, in the region corresponding to the above-mentioned shoulder Sh, and the magnetic powder is slightly oriented in the weak magnetic field. Is performed, the shoulder Sh ′ in the circumferential magnetic force pattern as shown in FIG. 14 is substantially eliminated, and a smooth circumferential magnetic force pattern as shown in FIG. 15 is obtained. Can be.
従ってこの成形方法では、 プラスチックマグネッ卜の形状の変更等を伴うそれ の最終形状の特定、 その最終形状に基づく成形金型もしくはダイの製作等なしに、 所期した通りの周方向磁力パターンを、 短時間のうちに容易に実現することがで さる。  Therefore, in this molding method, the expected circumferential magnetic force pattern can be obtained without specifying the final shape of the plastic magnet, which involves a change in shape, etc., and manufacturing a molding die or die based on the final shape. It can be easily realized in a short time.
( 2 )  (2)
以上のような方法の実施に用いて好適な、 本発明に係る着磁ヨークは、 磁性材 料からなり、 プラスチックマグネッ卜の成形キヤビティもしくはダイ開口部に近 接させて配置されて、 成形キヤビティもしくはダイ開口部に磁場を形成するもの であり、 着磁ヨークの幅方向断面内で、 成形キヤビティもしくはダイ開口部に最 も近接して位置する狭幅突部の少なくとも一方側に、 その狭幅突部から遠ざかる につれて、 傾向的に成形キヤビティから離隔する後退部分を設けたものである。 ここで、 「傾向的」 とするのは、 成形キヤビティもしくはダイ開口部の形状、 後退部分の形状等との関連において、 後退部分が狭幅突部から遠ざかる途中で、 成形キヤビティに部分的に接近する場合をも、 上記発明中に含ませることを意図 したものである。  The magnetized yoke according to the present invention, which is preferably used for carrying out the above method, is made of a magnetic material, and is disposed in close proximity to a molding cavity of a plastic magnet or a die opening. A magnetic field is formed in the die opening, and at least one side of the molding cavity or the narrow projection located closest to the die opening in the cross section in the width direction of the magnetization yoke. As the distance from the part increases, a retreating part is provided which tends to be separated from the molding cavity. Here, the term “prone” refers to the molding cavity or the shape of the die opening, the shape of the receding portion, etc., and the retracted portion partially approaches the molding cavity while moving away from the narrow projection. Such cases are also intended to be included in the above invention.
このような着磁ヨークでは、 狭幅突部をもつて成形キャビティ内もしくはダイ 開口部内に強い磁場を形成することができ、 また後退部分によって、 相対的に弱 い磁場を形成することができるので、 それを、 前述した方法の実施に用いて、 先 に述べた通りの作用効果をもたらすことができる。 かかる着磁ヨークで、 狭幅突部に設けた後退部分は、 要求される磁気特性と、 後退部分を設けない元の磁気特性との関連において、 図 1 5で述べたように、 図 1 4に示す肩部 S hの消去のために、 または、 元来肩部の発生していない部分の 磁力を作為的に高めるために機能させることができ、 これらのことは、 狭幅突部 の一方側でだけ行わせることも、 両側でも行わせることもできる。 In such a magnetized yoke, a strong magnetic field can be formed in the molding cavity or the die opening with a narrow protrusion, and a relatively weak magnetic field can be formed by the receding portion. It can be used in the implementation of the method described above to provide the same effects as described above. In such a magnetized yoke, the recessed portion provided on the narrow projection has a relationship between the required magnetic characteristics and the original magnetic characteristics without the recessed portion, as described in FIG. It can be used to eliminate the shoulder Sh as shown in the figure, or to artificially increase the magnetic force in the part where the shoulder is not originally formed. It can be done only on the side or on both sides.
( 3 )  (3)
本発明の着磁ヨークは、 この後退部分を、 傾斜面状の、 または、 一もしくは複 数のステップ状の後退部分とするものである。  In the magnetized yoke according to the present invention, the recessed portion is an inclined surface or one or a plurality of step-shaped recessed portions.
この着磁ヨークによれば、 この後退部分を傾斜面状のものとしたときは、 成形 キヤビティもしくはダイ開口部に形成される磁場を、 狭幅突部から遠ざかるにつ れて漸次弱めることができ、 また、 ステップ状のものとしたときは段階的に弱め ることができる。  According to this magnetized yoke, when the receding portion is formed as an inclined surface, the magnetic field formed in the molding cavity or the die opening can be gradually weakened as the distance from the narrow projection increases. Also, when it is made into a step shape, it can be gradually reduced.
( 4 )  ( Four )
本発明のマグネットローラの製造方法は、 シャフトの外周に、 樹脂バインダに 磁性粉体を混合分散した樹脂材料よりなる複数の棒状のマグネットピースを、 周 方向に隣接させて、 円柱状に形成され、 円柱の周面上に、 軸方向に延在する磁極 を複数極有するシャフト付マグネットローラの製造方法において、  In the method of manufacturing a magnet roller according to the present invention, a plurality of rod-shaped magnet pieces made of a resin material in which a magnetic powder is mixed and dispersed in a resin binder are formed in a columnar shape on the outer periphery of the shaft, adjacent to each other in the circumferential direction. A method of manufacturing a shaft-mounted magnet roller having a plurality of magnetic poles extending in an axial direction on a circumferential surface of a cylinder,
少なくとも一つの上記マグネットピースを、 少なくともその周方向一部分にお いて、 軸方向の両端部の磁力が、 軸方向中央部の磁力よりも低くなるよう着磁し た後、 このマグネットピースを残余のマグネットピースと組み合わせて形成する ものである。  After magnetizing at least one of the magnet pieces so that the magnetic force at both ends in the axial direction is lower than the magnetic force at the central portion in the axial direction at least in a part in the circumferential direction, the magnet pieces are removed from the remaining magnet pieces. It is formed in combination with a piece.
本発明のマグネットローラの製造方法は、 前述の第一の問題点に対応してなさ れたものである。 発明者らは、 従来のマグネットローラにおいて、 磁力が端部で 肩上がりする原因を調査するため、 マグネットピース単体の軸方向磁力分布と、 マグネットローラに組み合わせた後の、 このマグネットピースの部分の磁力分布 を比較した。 その結果、 マグネットピース単体の磁力分布では端部肩上がりがあ るものの、 マグネットピースが組み合わさった後のマグネットローラでは、 この 部分の端部の磁力はさらに大きく肩上がりが生じていることが分かった。 A method of manufacturing a magnet roller according to the present invention has been made in response to the first problem described above. In order to investigate the cause of the magnetic force rising at the end of the conventional magnet roller, the inventors have determined the axial magnetic force distribution of the magnet piece alone and the magnetic force of this magnet piece after being combined with the magnet roller. The distributions were compared. As a result, in the magnetic force distribution of the magnet piece alone, However, with the magnet roller after the magnet pieces were combined, it was found that the magnetic force at the end of this portion was even greater and the shoulder was raised.
本発明に係るマグネットローラの製造方法は、 新たに得られたこの知見に基づ いてなされたものであり、 この製造方法によれば、 マグネットピース同士を組み 合わせる際発生する端部肩上がりの磁力増加の分だけ、 軸方向端部磁力を軸方向 中央部分に比して低くしてマグネットピースを形成するので、 マグネットピース 同士を組み合わせたとき、 この組み合わせで発生する端部肩上がり現象により、 マグネットロ一ルの軸方向端部の磁力はちようど中央部分の磁力とほぼ等しくな り、 軸方向に均一な磁力分布をもつマグネットローラを形成することができる。 そしてこのことにより、 マグネットローラを形成後にこれを研削する等の工程を 必要とせず、 簡易にそして安価にマグネットロ一ラを製造することができる。  The manufacturing method of the magnet roller according to the present invention is based on this newly obtained knowledge, and according to this manufacturing method, the magnetic force generated by ascending the end shoulder when combining the magnet pieces is generated. The magnet piece is formed by lowering the magnetic force at the end in the axial direction compared to the central part in the axial direction by the amount of the increase, so when the magnet pieces are combined with each other, The magnetic force at the axial end of the roll is almost equal to the magnetic force at the center of the roll, and a magnet roller having a uniform magnetic force distribution in the axial direction can be formed. As a result, a step of grinding the magnet roller after forming the magnet roller is not required, and the magnet roller can be manufactured simply and at low cost.
( 5 )  ( Five )
本発明のマグネットローラの製造方法は、 （4 ) に記載された発明において、 前記複数極の磁極のうち、 互いに隣接し同じ極性を有する少なくとも一対の反発 極を有し、 これらの反発極同士の間の周面に、 磁力がほぼゼロで、 周方向の磁力 分布が平坦なゼロガウス帯を設けたマグネットローラの製造方法であって、 このゼロガウス帯を含み、 この両側の反発極に隣接する部分を、 軸方向の両端 部の磁力が、 軸方向中央部の磁力よりも低くなるよう着磁する前記マグネットピ ースとするものである。  The method of manufacturing a magnet roller according to the present invention, wherein in the invention described in (4), among the plurality of magnetic poles, at least one pair of repulsive poles which are adjacent to each other and have the same polarity is provided. A method of manufacturing a magnet roller having a zero Gaussian band in which a magnetic force is substantially zero and a circumferential magnetic force distribution is flat on a peripheral surface between the magnetic rollers. The magnet pieces are magnetized so that the magnetic force at both ends in the axial direction is lower than the magnetic force at the central part in the axial direction.
複写機等に用いられるマグネットローラにおいて、 トナーの回収率を向上させ るため、 マグネットローラの周上に配置した複数の磁極もうち、 少なくとも一組 の互いに隣接する反発極を配置し、 これらの反発極同士の間の周面に、 磁力がほ ぼゼロで、 周方向の磁力分布が平坦なゼロガウス帯をもつマグネットローラが用 いられている。 このようなゼロガウス帯は、 一般的に、 それ自体の磁ィ匕の強さが 小さいため、 その周方向両側に位置する反発極の影響を受け、 その磁力分布は不 安定になりやすく、 特に、 その軸方向端部の磁力は、 端部の不連続さによる影響 を受けて、 さらに不安定となり、 通常の磁極よりも端部の磁力の肩上がり現象を 抑制するのがむつかしいという問題があつた。 In a magnetic roller used in a copying machine or the like, at least one set of repulsive poles adjacent to each other is disposed among a plurality of magnetic poles disposed on the periphery of the magnet roller in order to improve a toner recovery rate. On the peripheral surface between the poles, a magnet roller having a zero gauss band with almost zero magnetic force and a flat magnetic force distribution in the circumferential direction is used. Generally, such a zero Gaussian band has a small strength of its own magnetic field, and is affected by repulsion poles located on both sides in the circumferential direction, and its magnetic force distribution tends to be unstable. The magnetic force at the axial end is affected by the discontinuity at the end As a result, it became more unstable, and it was more difficult to suppress the phenomenon of magnetic force rising at the end than in normal magnetic poles.
このマグネットローラの製造方法においては、 ゼロガウス帯を含み、 反発極間 に隣接して組み合わされるマグネットピースの軸方向の両端部の磁力が、 軸方向 中央部の磁力よりも低くなるよう着磁するので、 これをマグネットローラに組み 合わせた後、 端部磁力の肩上がり作用により、 軸方向の磁力を均一とすることが できるので、 特に有利な効果をもたらすことができる。  In this method of manufacturing the magnet roller, the magnet pieces including the zero Gauss band are magnetized so that the magnetic force at both ends in the axial direction of the magnet piece combined adjacently between the repulsion poles is lower than the magnetic force at the central portion in the axial direction. After combining this with the magnet roller, the magnetic force in the axial direction can be made uniform by the shoulder magnetic force of the end portion, so that a particularly advantageous effect can be brought about.
( 6 )  (6)
本発明のマグネットローラの製造方法は、 （5 ) に記載された発明において、 前記ゼロガウス帯を具えたマグネットピースを、 シャフ卜の外周面に対応する、 断面湾曲形状に形成され軸方向に延在する内周面の側に前記反発極と逆の極性を 有する磁極を形成し、 内周面に隣接する両側の側面の側に、 それぞれ、 反発極と 同じ極性を有する磁極を形成した後、 このマグネットピースを消磁し、  The method of manufacturing a magnet roller of the present invention according to the invention described in (5), wherein the magnet piece having the zero Gaussian band is formed in a curved sectional shape corresponding to the outer peripheral surface of the shaft and extends in the axial direction. After forming a magnetic pole having a polarity opposite to that of the repulsion pole on the side of the inner peripheral surface to be formed, and forming a magnetic pole having the same polarity as the repulsion pole on each of the side surfaces on both sides adjacent to the inner peripheral surface, Demagnetize the magnet piece,
その後、 マグネットピースの内周面側の対向位置に、 内周面を反発極と逆の極 性に着磁する着磁ヨークを配置し、 両方の前記側面の側の対向位置に、 これら側 面を反発極と同じ極性に着磁する着磁ヨークを配置するとともに、 外周面側の軸 方向両端部分の対向位置に、 これら両端部分にゼロガウス帯と逆の極性の磁力を 加える着磁ヨークを配置して、 軸方向の両端部の磁力が、 軸方向中央部の磁力よ りも低くなるよう着磁するものである。  Then, a magnetizing yoke for magnetizing the inner peripheral surface to the polarity opposite to the repulsion pole is arranged at a position facing the inner peripheral surface side of the magnet piece, and these magnets are placed at opposing positions on both the side surfaces. And a magnetizing yoke that applies a magnetic force with a polarity opposite to that of the zero gauss band to both ends in the axial direction on the outer peripheral surface opposite to the opposite ends in the axial direction. Then, the magnets are magnetized so that the magnetic force at both ends in the axial direction is lower than the magnetic force at the central portion in the axial direction.
このマグネットローラの製造方法は、 前述の通り、 特にその磁力形成が難しい ゼロガウス帯に関したもので、 シャフトの内周面の側に前記反発極と逆の極性の 磁極を形成し、 両側の側面の側に、 それぞれ、 前記反発極と同じ極性の磁極を形 成した後、 このマグネットピースを消磁し、 その後、 マグネットピースの内周面 側の対向位置に、 内周面を反発極と逆の極性に着磁する着磁ヨークを配置し、 両 方の前記側面の側の対向位置に、 これら側面を反発極と同じ極性に着磁する着磁 ヨークを配置するので、 このマグネットピース内に、 その両側面から内周面に向 かって強く配向した磁石を形成することにより、 このマグネットピースの外周面 から外部に向かう磁力線の数を抑制して、 ゼロガウス帯の磁力をほぼゼロとする ことができる。 As described above, the method of manufacturing this magnet roller relates to a zero gauss band, in which it is particularly difficult to form a magnetic force.A magnetic pole having a polarity opposite to that of the repulsion pole is formed on the inner peripheral surface of the shaft. After forming a magnetic pole having the same polarity as the repelling pole on the side, the magnet piece is demagnetized, and then the inner circumferential surface of the magnet piece is opposite in polarity to the repelling pole at the opposing position on the inner circumferential surface side of the magnet piece. A magnetizing yoke that magnetizes these magnets is arranged, and magnetizing yokes that magnetize these sides to the same polarity as the repulsion poles are arranged at opposite positions on both sides of the magnet. From both sides to the inner circumference By thus forming a strongly oriented magnet, the number of lines of magnetic force directed outward from the outer peripheral surface of the magnet piece can be suppressed, and the magnetic force in the zero gauss band can be reduced to almost zero.
さらに、 このマグネットローラの製造方法では、 マグネットピースを消磁した 後、 このマグネットピースの内周面および両側面に配置した前述の着磁ヨークに 加えて、 外周面側の軸方向両端部分の対向位置の両端部分にも、 ゼロガウス帯と 逆の極性の磁力を加える着磁ヨークを配置することにより、 このマグネットピー スの軸方向の両端部の磁力が、 軸方向中央部の磁力よりも低くなるよう着磁する ので、 前述の通り、 これを円柱状のマグネットローラに組み合わせた後、 ゼロガ ウス帯での軸方向の磁力分布が均一なマグネットロ一ラを形成することができる。  Further, in the method of manufacturing the magnet roller, after the magnet piece is demagnetized, in addition to the above-described magnetized yokes arranged on the inner circumferential surface and both side surfaces of the magnet piece, the opposing positions of the axially opposite end portions on the outer circumferential surface side are further reduced. A magnetizing yoke that applies a magnetic force of the opposite polarity to the zero Gaussian band is also arranged at both ends of the magnet piece so that the magnetic force at both ends in the axial direction of this magnet piece is lower than the magnetic force at the central part in the axial direction. Since it is magnetized, as described above, after it is combined with a cylindrical magnet roller, a magnet roller having a uniform magnetic distribution in the axial direction in the zero Gauss band can be formed.
( 7 )  (7)
本発明のマグネットローラの製造方法は、 （6 ) に記載された発明において、 マグネットピースの外周面側の軸方向両端部分の対向位置に配置する前記着磁ョ ークを、 軸方向中央部から遠ざかるにつれてマグネットピースの周面に近接する よう傾斜させて配置するものである。  The method of manufacturing a magnet roller according to the present invention is characterized in that, in the invention described in (6), the magnetized shock arranged at a position opposite to both axial ends on the outer peripheral surface side of the magnet piece is positioned from a central portion in the axial direction. It is arranged to be inclined so that it gets closer to the peripheral surface of the magnet piece as it goes away.
このマグネットローラの製造方法によれば、 マグネットピースの外周面側の軸 方向両端部分の対向位置に配置する前記着磁ヨークを、 軸方向中央部から遠ざか るにつれてマグネットピースの周面に近接するよう傾斜させて配置したので、 マ グネットピースのゼロガウス帯に、 軸方向の中央部から端部に向かって滑らかに 磁力が低下する磁力分布を形成することができ、 この磁力分布は、 このマグネッ トピースをマグネットローラに組み合わせたときに現れる端部肩上がり作用とち ようど打ち消すように作用するので、 マグネットピースを組み合わせた後の状態 において、 軸方向の中央部分から端部まで均一な磁力分布のゼロガウス帯を有す るマグネットローラを形成することができる。  According to this method of manufacturing a magnet roller, the magnetized yoke, which is disposed at a position opposed to both ends in the axial direction on the outer peripheral surface side of the magnet piece, is moved closer to the peripheral surface of the magnet piece as the distance from the axial center increases. Since the magnet pieces are arranged at an inclination, a magnetic force distribution in which the magnetic force decreases smoothly from the center in the axial direction toward the end can be formed in the zero gauss band of the magnet piece. Since it works to cancel the edge rise when it is combined with the magnet roller, it works to cancel the edges, so the zero Gaussian band with uniform magnetic force distribution from the axial center to the end in the state after the magnet piece is combined It is possible to form a magnet roller having the following.
図面の簡単な説明 BRIEF DESCRIPTION OF THE FIGURES
図 1は、 着磁ヨークの適用例を示す縦断面図である。 図 2は、 射出成形に供される金型装置を例示する要部断面図である。 FIG. 1 is a longitudinal sectional view showing an application example of a magnetized yoke. FIG. 2 is a cross-sectional view of a main part illustrating a mold apparatus used for injection molding.
図 3は、 着磁ヨークの他の形態を示す縦断面図である。  FIG. 3 is a longitudinal sectional view showing another embodiment of the magnetization yoke.
図 4は、 後退部分の変更例を示す図である。  FIG. 4 is a diagram showing a modified example of the retreat portion.
図 5は、 マグネットローラを示す略線断面図である。  FIG. 5 is a schematic sectional view showing a magnet roller.
図 6は、 マグネットローラの磁力パターン図である。  FIG. 6 is a magnetic force pattern diagram of the magnet roller.
図 7は、 マグネットピースのゼロガウス帯の磁力分布を示すグラフである。 図 8は、 マグネットローラのゼロガウス帯の磁力分布を示すグラフである。 図 9は、 マグネットピースの磁化の配向を示す断面図である。  FIG. 7 is a graph showing the magnetic force distribution of the magnet piece in the zero Gauss band. FIG. 8 is a graph showing the magnetic force distribution of the magnet roller in the zero Gauss band. FIG. 9 is a cross-sectional view showing the magnetization orientation of the magnet piece.
図 1 0は、 着磁ヨークの配置を示す側面図である。  FIG. 10 is a side view showing the arrangement of the magnetization yoke.
図 1 1は、 図 1 0の XI— XI断面図である。  FIG. 11 is a sectional view taken along the line XI-XI of FIG.
図 1 2は、 従来の方法で製造したマグネットローラの断面図である。  FIG. 12 is a sectional view of a magnet roller manufactured by a conventional method.
図 1 3は、 従来の着磁ヨークを用いた成形金型の縦断面図である。  FIG. 13 is a longitudinal sectional view of a molding die using a conventional magnetized yoke.
図 1 4は、 従来のマグネットローラの周方向磁力パターンを例示する図である。 図 1 5は、 修正後の周方向磁力パターンを例示する図である。  FIG. 14 is a diagram illustrating a circumferential magnetic force pattern of a conventional magnet roller. FIG. 15 is a diagram illustrating a circumferential magnetic force pattern after correction.
図 1 6は、 従来の方法で製造したマグネットローラの N極の磁力分布を示すグ ラフである。  Figure 16 is a graph showing the magnetic force distribution of the N pole of a magnet roller manufactured by a conventional method.
図 1 7は、 従来の方法で着磁したマグネットピースのゼロガウス帯の磁力分布 を示すグラフである。  Fig. 17 is a graph showing the magnetic force distribution in the zero gauss band of a magnet piece magnetized by a conventional method.
発明を実施するための最良の形態 BEST MODE FOR CARRYING OUT THE INVENTION
以下にこの発明の実施の形態を図面に示すところに基づいて説明する。  Hereinafter, embodiments of the present invention will be described with reference to the drawings.
まず、 第一の問題点に対応する発明の実施形態、 すなわち第一の実施形態につ いて説明する。 図 1は、 この発明に係る着磁ヨークの適用例を示す成形金型の縦 断面図であり、 図中 1は上型を、 2は下型をそれぞれ示し、 3は、 上下型間に形 成されて、 断面形状がほぼ扇形をなす成形キヤビティを示す。  First, an embodiment of the invention corresponding to the first problem, that is, a first embodiment will be described. FIG. 1 is a longitudinal sectional view of a molding die showing an application example of a magnetized yoke according to the present invention. In the drawing, 1 shows an upper die, 2 shows a lower die, and 3 shows a shape between the upper and lower dies. It shows a molded cavity that has a substantially sectorial cross-section.
ここでは、 上型 1に着磁ヨーク 4を固定配置して、 この着磁ヨーク 4の狭幅突 部 5の先端面を、 成形キヤビティ 3を区画する上型円弧面 6の中央部と対応する 位置で、 その円弧面 6に近接させて位置させるとともに、 着磁ヨーク 4の幅方向 断面内の、 その狭幅突部 5の一方側、 図では左方側に、 狭幅突部 5から遠ざかる につれて成形キヤビティ 3から次第に離隔する、 傾斜面状の後退部分 7をその着 磁ヨーク 4に設ける。 Here, the magnetized yoke 4 is fixedly arranged on the upper mold 1, and the distal end face of the narrow projection 5 of the magnetized yoke 4 corresponds to the center of the upper mold arc surface 6 that defines the molding cavity 3. At the position, close to the arc surface 6, and away from the narrow protrusion 5 to one side of the narrow protrusion 5 in the width direction cross section of the magnetized yoke 4, that is, the left side in the figure. The magnetized yoke 4 is provided with an inclined surface-like recessed portion 7 that is gradually separated from the molding cavity 3 as the angle increases.
この成形金型では、 このような着磁ヨーク 4を、 非磁性材 8によって囲繞する とともに、 その上面を磁性材 9によってバックアツプして上型 1に取付けており、 そしてまた、 成形キヤビティ 3を区画する下型 2の窪み部 1 0を磁性材 1 1に形 成している。  In this molding die, such a magnetized yoke 4 is surrounded by a non-magnetic material 8, and the upper surface thereof is backed up by a magnetic material 9 and attached to the upper mold 1, and the molding cavity 3 is also formed. The recessed portion 10 of the lower mold 2 to be partitioned is formed in the magnetic material 11.
以上のような成形金型 1 2は、 たとえば、 図 2に部分断面図で示すように、 そ の四個を一組みとして金型装置 1 3とされて射出成形に供される。 この場合、 各 金型 1 2の着磁ヨーク 4は、 装置 1 3の周りに配設した着磁コイル 1 4への通電 に基づいて、 成形キヤビティ 3内に磁場を形成し、 また、 図示しない射出ノズル から射出された、 磁性粉を含む溶融樹脂材料は、 スプルー 1 5からランナ 1 6お よび、 図外のゲートを経て成形キヤビティ 3内に加圧充填される。  For example, as shown in a partial cross-sectional view of FIG. 2, the above-described molding die 12 is made into a mold device 13 as a set of four parts, and is subjected to injection molding. In this case, the magnetized yoke 4 of each mold 12 forms a magnetic field in the molding cavity 3 based on the energization of the magnetized coil 14 disposed around the device 13, and is not shown. The molten resin material containing the magnetic powder injected from the injection nozzle is pressure-filled into the molding cavity 3 from a sprue 15 through a runner 16 and a gate (not shown).
このようにして成形キヤビティ 3内へ充填された樹脂材料は、 図 1に磁束線を 破線で示すように、 その密度の高い、 着磁ヨーク 4の狭幅突部 5と対応する領域 で強い磁場の影響を受け、 これより、 その領域では磁性粉が集中配向され、 そこ に磁極が付与される。 一方、 後退部分 7と対応する領域 1 7では、 樹脂材料が相 対的に弱い磁場の影響を受けることに基づいて、 磁性粉の幾分の配向が行われる。 そしてこれらのことにより、 後退部分 7を設けない従来の着磁ヨーク 8 5を用 いた場合には、 図 1 4に示すような、 肩部 S h付きの周方向磁力パターンとなる ところ、 後退部分 7を設けた、 この発明に係る着磁ヨーク 4では、 図 1 5に示す ような周方向磁力パターンを容易に実現することができる。  The resin material filled in the molding cavity 3 in this manner has a strong magnetic field in a region corresponding to the high-density magnetized yoke 4 and the narrow projections 5 as indicated by broken lines in FIG. From this, the magnetic powder is concentrated and oriented in that region, and a magnetic pole is provided there. On the other hand, in the region 17 corresponding to the receding portion 7, some orientation of the magnetic powder is performed based on the fact that the resin material is affected by the relatively weak magnetic field. Due to these facts, when a conventional magnetized yoke 85 without the retreat portion 7 is used, a circumferential magnetic force pattern with a shoulder Sh is obtained as shown in FIG. In the magnetized yoke 4 according to the present invention provided with 7, the circumferential magnetic force pattern as shown in FIG. 15 can be easily realized.
なおこの場合において、 図 1に示す後退部分 7に代えてもしくは加えて、 狭幅 突部 5の右方側に、 先の場合と同様の、 または形状を変えた後退部分を設けるこ ともでき、 これによれば、 前記周方向磁力パターンの、 ピークの反対側の磁力を 増加させることができる。 In this case, instead of or in addition to the recessed portion 7 shown in FIG. 1, a recessed portion similar to or different in shape from the previous case may be provided on the right side of the narrow protrusion 5. According to this, the magnetic force on the opposite side of the peak in the circumferential magnetic force pattern is Can be increased.
図 3は、 着磁ヨークの他の形態を示す断面図であり、 これは、 成形されるマグ ネットピースの一方の側部、 図では右側部に偏せて磁極を形成するとともに、 周 方向磁力パターンの、 磁極近傍への肩部の発生を防止することを目的とし、 狭幅 突部 5の左方側に、 先の場合より広幅になる傾斜面状の後退部分 7を設けたもの である。  FIG. 3 is a cross-sectional view showing another form of the magnetized yoke. The magnetized yoke is formed so as to be biased to one side of the magnet piece to be formed, that is, to the right side in the figure, and to have a circumferential magnetic force. In order to prevent the occurrence of a shoulder near the magnetic pole of the pattern, a recessed portion 7 with an inclined surface that is wider than in the previous case is provided on the left side of the narrow protrusion 5. .
この場合にもまた、 後退部分 7の作用下で、 それと対応する領域 1 7に弱い磁 場を形成して、 そこでの磁性粉の配向をもたらすことによって所期の目的を達成 することができる。  Also in this case, the intended purpose can be achieved by forming a weak magnetic field in the corresponding region 17 under the action of the receding portion 7 to bring the orientation of the magnetic powder there.
図 4は、 着磁ヨークの後退部分の変更例を示す図であり、 図 4 aは、 その後退 部分 7を狭幅突部 5の先端面に直接連続する傾斜面状に形成したものであり、 図 1、 図 3に示すところから、 成形キヤビティ 3から離隔する方向のステップダウ ン部分を省いたものに相当する。  FIG. 4 is a diagram showing a modified example of the retreating portion of the magnetized yoke, and FIG. 4a is a diagram in which the retreating portion 7 is formed into an inclined surface directly continuing to the distal end surface of the narrow projection 5. 1 and 3, this corresponds to a case where the step-down portion in the direction away from the molding cavity 3 is omitted.
また、 図 4 bは、 後退部分 7を、 狭幅突部 5の先端面からステップダウンする 一段の水平面状としたものである。  FIG. 4B shows the retreating portion 7 in the form of a single horizontal plane stepping down from the distal end surface of the narrow projection 5.
これらによれば、 後退部分 7の形状に基づいて、 その後退部分 7にて形成され る磁場の強さを所要に応じて選択することができる。  According to these, based on the shape of the receding portion 7, the strength of the magnetic field formed in the receding portion 7 can be selected as required.
従って、 図 4 aに示すところにおいて、 後退部分 7の傾斜角度を適宜変更する こと、 図 4 bに示すところにおいて、 後退部分 7を二段以上のステップ状とする ことも可能である。  Therefore, it is possible to appropriately change the inclination angle of the retreating portion 7 in the place shown in FIG. 4A, and to make the retreating portion 7 into a step shape of two or more steps in the place shown in FIG. 4B.
次に、 第二の問題点に対応する発明の実施形態、 すなわち第二の実施形態につ いて、 図 5〜図 1 1に基づいて説明する。 図 5は、 本発明に係るマグネットロー ラ 2 1の断面を示す略線断面図である。 マグネットローラ 2 1はシャフト 2 2の 周りに、 周方向に互いに隣接する六個の棒状のマグネットピース 3 1〜3 6を組 み合わせて形成され、 これらのマグネットピース 3 1〜3 6は、 それぞれ、 順に N 1〜N 3極、 S 1極、 S 2極の磁極およびゼロガウス帯 N Oを有する。 ここで、 N 1〜N 3極はN、 S 1〜S 2極は Sの極性をもつ磁極であり、 このうち、 N 2 と N 3とが対をなす反発極である。 Next, an embodiment of the invention corresponding to the second problem, that is, a second embodiment will be described with reference to FIGS. FIG. 5 is a schematic cross-sectional view showing a cross section of the magnet roller 21 according to the present invention. The magnet roller 21 is formed by combining six rod-shaped magnet pieces 31 to 36 adjacent to each other in the circumferential direction around the shaft 22. These magnet pieces 31 to 36 are respectively , Which have N 1 to N 3 poles, S 1 pole, S 2 pole magnetic poles, and zero Gaussian band NO. here, The N1 to N3 poles are magnetic poles having the polarity of N, and the S1 to S2 poles are magnetic poles having the polarity of S. Of these, N2 and N3 are repulsive poles forming a pair.
図 6は、 このマグネットローラ 2 1の周面上の磁力を測定した、 周方向の磁力 パターンを示すグラフであり、 横軸は周方向の位置を角度で表し、 縦軸は磁力の 大きさを表す。 マグネットローラ 2 1は、 対をなす反発極 N 2と N 3との間に、 磁力の極性が Nで、 磁力がほぼゼロのまま周方向に平坦に広がる磁力分布をもつ ゼロガウス帯を設けている。  FIG. 6 is a graph showing a circumferential magnetic force pattern obtained by measuring the magnetic force on the circumferential surface of the magnet roller 21. The horizontal axis represents the circumferential position by an angle, and the vertical axis represents the magnitude of the magnetic force. Represent. The magnet roller 21 has a zero Gaussian band between the pair of repulsive poles N 2 and N 3 having a magnetic force distribution of N and a magnetic force distribution which spreads flat in the circumferential direction while the magnetic force is almost zero. .
図 7は、 マグネットローラ 2 1に組み合わせる前のマグネットピース 3 6にお けるゼロガウス帯 N 0の軸方向の磁力分布を表すグラフであり、 横軸は軸方向の 位置を表し、 縦軸は磁力の大きさを表す。 P 1〜P 2の範囲が、 このマグネット ローラ 1を装置に装着したときの磁力の有効範囲であり、 このマグネットローラ の製造方法においては、 マグネットピース 3 6を着磁するに際して、 P 1および P 2の近傍の端部付近の軸方向位置における磁力を、 軸方向中央部の磁力より小 さく形成し、 しかも、 この磁力を端部に向かうほど小さくなるよう形成する。 図 8は、 マグネットピース 3 6を他のマグネットピース 3 1〜 3 5と組み合わ せてマグネットローラ 2 1を形成した後の、 ゼロガウス帯 N Oの軸方向磁力分布 を示すグラフであり、 マグネットピース 3 1〜 3 6を組み合わせた後のマグネッ トロ一ラでは、 ゼロガウス帯 N Oの磁力を、 軸方向に均一に分布させ、 しかもそ の磁力をほぼゼロになるように制御することが可能であることを示している。 このように、 マグネットロ一ラ 2 1に軸方向に均一な磁力分布を付与するため には、 マグネットローラ 2 1に組み合わせ前のマグネットピース 3 6のゼロガウ ス帯における端部磁力を中央部より小さくしておくことが肝要であり、 これは次 に例示する方法で達成することができる。  FIG. 7 is a graph showing the magnetic distribution in the axial direction of the zero Gaussian band N 0 in the magnet piece 36 before being combined with the magnetic roller 21.The horizontal axis represents the axial position, and the vertical axis represents the magnetic force. Indicates the size. The range of P1 to P2 is the effective range of the magnetic force when the magnet roller 1 is mounted on the apparatus. In the method of manufacturing the magnet roller, when magnetizing the magnet piece 36, P1 and P2 are used. The magnetic force at the axial position near the end near 2 is formed to be smaller than the magnetic force at the center in the axial direction, and the magnetic force becomes smaller toward the end. FIG. 8 is a graph showing the axial magnetic force distribution of the zero Gaussian band NO after forming the magnet roller 21 by combining the magnet piece 36 with the other magnet pieces 31 to 35. After the combination of ~ 36, the magnetometer shows that it is possible to distribute the magnetic force in the zero Gaussian band NO uniformly in the axial direction and to control the magnetic force to be almost zero. ing. As described above, in order to impart a uniform magnetic force distribution in the axial direction to the magnet roller 21, the magnetic force at the end of the magnet piece 36 before being combined with the magnet roller 21 in the zero-gauss band is smaller than that in the center. It is important to keep this in mind, and this can be achieved by the following method.
まず、 磁性紛を混合した樹脂材料を、 磁場をかけた金型のキヤビティ内に射出 するか、 あるいは、 この材料を、 磁場をかけた押出ヘッド内を押出して、 マグネ ットピース 3 6を成型する。 図 9は、 この段階で成型されたマグネットピース 3 6の断面における磁性紛の配向を示す断面図であり、 磁性紛の配向が、 このマグ ネットピース 3 6の内周面 4 1側を S極とし、 両側面 4 2の側を N極となるよう、 金型もしくは押出しヘッドに磁場をかけて成型する。 次いで、 このマグネットピ ース 3 6に、 交流磁場をかけて、 一旦これを消磁したあと、 このマグネットピー ス 3 6の周囲に着磁ヨークを配置して、 このピース 3 6を着磁する。 First, a resin material mixed with magnetic powder is injected into a mold cavity to which a magnetic field is applied, or the material is extruded through an extrusion head to which a magnetic field is applied to form a magnet piece 36. Figure 9 shows the magnet piece 3 molded at this stage. FIG. 6 is a cross-sectional view showing the orientation of the magnetic powder in the cross section of FIG. 6, wherein the orientation of the magnetic powder is such that the inner peripheral surface 41 side of the magnet piece 36 is an S pole, and both side surfaces 42 are N poles. Apply a magnetic field to the mold or extrusion head. Next, an AC magnetic field is applied to the magnet piece 36 to demagnetize it once, and a magnetizing yoke is arranged around the magnet piece 36 to magnetize the piece 36.
図 1 0は、 着磁ヨークの配置を示す側面図であり、 図 1 1は、 図 1 0の XI— XI 断面を示す断面図である。 マグネットピース 3 6の内周面 4 1に対向させて 極性が Nの着磁ヨーク 5 1を配置し、 そして、 両方の側面 2 2に対向させて極性 が Sの着磁ヨーク 5 2を配置し、 内周面 4 1を S極に、 両側面 4 2を N極に着磁 する。  FIG. 10 is a side view showing the arrangement of the magnetized yokes, and FIG. 11 is a cross-sectional view showing a XI-XI cross section of FIG. A magnetized yoke 51 of polarity N is arranged facing the inner peripheral surface 41 of the magnet piece 36, and a magnetized yoke 52 of polarity S is arranged facing both sides 22. The inner peripheral surface 41 is magnetized to the S pole, and both side surfaces 42 are magnetized to the N pole.
このとき同時に、 マグネットピース 3 6の外周面 4 3の両端部に、 極性が Nの 着磁ヨーク 5 3を配置することにより、 もともと、 わずか N極側に配向したセロ ガウス帯 N Oの端部の磁力を減磁する。 さらに、 着磁ヨーク 5 3を、 マグネット ピース 3 6の軸方向中央部から端部に向かうにしたがって、 徐々に、 マグネット ピース 3 6の外周面 4 3に近接するよう傾斜して配設し、 そのため、 マグネット ピース 3 6の外周面 4 3と着磁ヨーク 5 3との間に、 断面三角形状の非磁性のス ぺーサ 5 4を設けている。  At the same time, by arranging the magnetizing yokes 53 with N polarity on both ends of the outer peripheral surface 43 of the magnet piece 36, the end of the cellogauss band NO originally oriented slightly toward the N pole Demagnetize the magnetic force. Further, the magnetizing yoke 53 is gradually inclined from the axial center to the end of the magnet piece 36 so as to approach the outer peripheral surface 43 of the magnet piece 36. A nonmagnetic spacer 54 having a triangular cross section is provided between the outer peripheral surface 43 of the magnet piece 36 and the magnetized yoke 53.
以上のように着磁ヨーク 5 1〜5 3を配設して、 マグネットピース 3 6を着磁 することにより、 図 3に示す、 軸方向端部の磁力が、 中央部の磁力より低い磁力 分布のゼロガウス帯 N Oを有するマグネットピース 3 6を形成することができる。 ここにおいて、 着磁ヨーク 5 3の作用は、 もしこれがなければ、 このマグネッ トピース 3 6は、 端部磁力が肩上がりした、 図 1 7に示すような軸方向磁力分布 を示すこととなり、 このようなマグネットピース 3 6をマグネットローラに組み 合わせると、 軸方向の端部の磁力がさらに強調されて肩上がりしてしまい、 実用 に供することができなかつたものを改善したことにある。  By arranging the magnetizing yokes 51 to 53 and magnetizing the magnet pieces 36 as described above, the magnetic force distribution at the axial end is lower than the magnetic force at the center as shown in Fig. 3. The magnet piece 36 having the zero Gaussian band NO can be formed. Here, if the magnetizing yoke 53 does not have this effect, the magnet piece 36 will have an axial magnetic force distribution as shown in FIG. When a simple magnet piece 36 is combined with a magnet roller, the magnetic force at the end in the axial direction is further emphasized and the shoulder rises, which is an improvement over what could not be used for practical use.
なお、 上述の製造方法において、 磁場中成型したマグネットピース 3 6を一旦消 磁した後、 再着磁を行ったが、 消磁をせずに、 再着磁を行っても、 着磁条件次第 では同様の効果を得ることができる。 また、 この実施形態では、 ゼロガウス帯を もつマグネットピース 3 6について説明したが、 その効果の大小は別として、 他 のマグネットピース 3 1〜3 5に対しても、 これらを、 マグネットローラに組み 込む前の状態で、 軸方向端部の磁力を中央部の磁力より減じておくことによって、 マグネットローラに組み合わせた後の軸方向の磁力分布をより均一なものとする ことができる。 In the above-described manufacturing method, the magnet piece 36 molded in a magnetic field was temporarily erased. After magnetizing, re-magnetization was performed. Even if re-magnetization is performed without degaussing, the same effect can be obtained depending on the magnetizing conditions. Further, in this embodiment, the magnet piece 36 having a zero Gaussian band has been described. However, apart from the magnitude of the effect, these are incorporated into the magnet roller for other magnet pieces 31 to 35 as well. By reducing the magnetic force at the axial end portion from the magnetic force at the central portion in the previous state, the axial magnetic force distribution after combination with the magnet roller can be made more uniform.
実施例 Example
磁性紛を混合した樹脂材料を、 磁場をかけた金型内に射出してマグネットピー ス 3 6を成型した後これを消磁し、 その後、 図 1 0、 図 1 1に示すように着磁ョ —ク 5 1〜5 3を配置して、 マグネットピース 3 6を再着磁し、 このピース 3 6 を組み込んで、 図 5に示す断面のものに製造したマグネットローラ 2 1を実施例 とし、 これを、 この実施例のマグネットローラ 2 1のゼロガウス帯 N Oの軸方向 の磁力分布を測定し、 図 1 0に示す着磁ヨークのうち着磁ヨーク 5 3を配置しな いでマグネットピース 3 6を着磁して形成した従来のマグネットロ一ラの磁力分 布と比較した。 従来例のマグネットローラの製造方法は、 着磁ヨーク 5 3を配置 していない以外は、 実施例のマグネットローラの製造方法と全く同じである。 また、 この比較に供したマグネットローラの外径は 1 4. 5 mmである。 そし て、 このマグネットローラの外周に配置して用いるスリーブの外径は 1 6 mmで あり、 したがって、 このマグネットローラの磁力の測定に際し、 測定プローブの 先端を、 マグネットローラの軸心から 8 mm離した位置に配置した。  The resin material mixed with the magnetic powder is injected into a mold to which a magnetic field is applied to form a magnet piece 36, which is then demagnetized, and then magnetized as shown in Figs. 10 and 11. The magnet pieces 36 are re-magnetized by placing the magnets 51 to 53, and the pieces 36 are incorporated into the magnet roller 21 manufactured to have a cross section shown in FIG. The magnetic force distribution in the axial direction of the zero Gaussian band NO of the magnet roller 21 of this embodiment was measured, and the magnet piece 36 was mounted without the magnetized yoke 53 of the magnetized yokes shown in FIG. It was compared with the magnetic force distribution of a conventional magnet roller formed by magnetizing. The method of manufacturing the magnet roller of the conventional example is exactly the same as the method of manufacturing the magnet roller of the embodiment except that the magnetizing yoke 53 is not provided. The outer diameter of the magnet roller used in this comparison is 14.5 mm. The outer diameter of the sleeve arranged on the outer periphery of the magnet roller is 16 mm. Therefore, when measuring the magnetic force of the magnet roller, the tip of the measurement probe is separated from the axis of the magnet roller by 8 mm. It was placed at the position.
表 1は、 実施例と従来例とのマグネットローラのゼロがウス帯の軸方向の磁力 分布の測定結果を、 それぞれ、 端部磁力の最大値、 および、 軸方向磁力有効範囲 における最大磁力から最小磁力を差し引いた磁力バラツキで示したものである。 このマグネットローラを装置に装着して、 画像を印刷するのに際し、 問題のない マグネットローラの端部磁力の最大値および磁力バラツキは、 それぞれ、 4 mT、 3 mTであり、 表 1は、 従来例のマグネットローラでは許容されないゼロガウス 帯の磁力分布が、 実施例の製造方法により製造したマグネットローラでは、 許容 されるレベルに改善されたことを示している。 表 1
Figure imgf000019_0001
産業上の利用可能性 Table 1 shows the measurement results of the magnetic force distribution in the axial direction of the zero-us band of the magnet roller of the embodiment and the conventional example, and the minimum value from the maximum value of the end magnetic force and the maximum magnetic force in the effective range of the axial magnetic force, respectively. It is shown by magnetic force variation from which magnetic force is subtracted. When printing the image with this magnet roller attached to the machine, the maximum value of the magnetic force at the end of the magnet roller and the variation in magnetic force are 4 mT, It is 3 mT, and Table 1 shows that the magnetic force distribution in the zero gauss band, which is not allowed by the conventional magnet roller, has been improved to an acceptable level by the magnet roller manufactured by the manufacturing method of the embodiment. table 1
Figure imgf000019_0001
Industrial applicability
以上に述べたところから明らかなように、 第一の問題点に対応する発明によれ ば、 とくに、 着磁ヨークの、 成形キヤビティに最も近接する部分で、 成形キヤビ ティ内に強い磁場を形成することに加え、 その強い磁場の形成域の少なくとも一 方側の所定領域で、 成形キヤビティ内に、 相対的に弱い磁場を形成することによ り、 プラスチックマグネットの周方向磁力パターンの所要に応じた修正ないしは 変更を、 従来技術のように多くのノウハウを必要とすることなく、 また短時間の うちに容易に実現することができ、 併せて、 プラスチックマグネットの、 常なる 射出成形を可能とすることができる。  As is clear from the above description, according to the invention corresponding to the first problem, a strong magnetic field is formed in the molding cavity, particularly at the portion of the magnetization yoke closest to the molding cavity. In addition, by forming a relatively weak magnetic field in the molding cavity in at least one side of the strong magnetic field forming area, the circumferential magnetic force pattern of the plastic magnet can be adjusted as required. Modifications or changes can be easily achieved in a short time without requiring much know-how as in the prior art, and also enable constant injection molding of plastic magnets. Can be.
また、 第二の問題点に対応する発明によれば、 マグネットピースを、 少なくとも その周方向一部分において、 軸方向の両端部の磁力が、 軸方向中央部の磁力より も低くなるよう着磁した後、 このマグネットピースを残余のマグネットピースと 組み合わせてマグネットローラを製造するので、 軸方向に均一な磁力分布を有す るマグネットローラ全体を磁力調整することなしに製造することができる。 According to the invention corresponding to the second problem, the magnet piece is magnetized so that the magnetic force at both ends in the axial direction is lower than the magnetic force at the central portion in the axial direction at least in a part in the circumferential direction. Since the magnet roller is manufactured by combining this magnet piece with the remaining magnet pieces, it is possible to manufacture the entire magnet roller having a uniform magnetic force distribution in the axial direction without adjusting the magnetic force.

Claims

請 求 の 範 囲 The scope of the claims
1 . 着磁ヨークによって磁場を形成した成形キヤビティ内へ、 磁性粉を配合した 樹脂材料を射出して、 もしくは、 着磁ヨークによって磁場を形成したダイ開口部 に磁性粉を配合した樹脂材料を押出して、 プラスチックマグネットを成形するに 当り、 1. Inject the resin material containing the magnetic powder into the molding cavity where the magnetic field is formed by the magnetized yoke, or extrude the resin material containing the magnetic powder into the die opening where the magnetic field is formed by the magnetized yoke. When molding plastic magnets,
着磁ヨークの、 成形キヤビティもしくはダイ開口部に最も近接する部分で、 そ の成形キヤビティもしくはダイ開口部に強い磁場を形成するとともに、 この強い 磁場の形成域の少なくとも一方側の所定領域で、 成形キヤビティ内もしくはダイ 開口部内に、 相対的に弱い磁場を形成するプラスチックマグネッ卜の成形方法。 A strong magnetic field is formed at the molding cavity or die opening at the portion of the magnetized yoke closest to the molding cavity or die opening, and the magnetic field is formed at a predetermined region on at least one side of the region where the strong magnetic field is formed. A method for molding plastic magnets that creates a relatively weak magnetic field in the cavity or die opening.
2 . プラスチックマグネットの成形キヤビティもしくはダイ開口部に近接させて 配置されて、 成形キヤビティもしくはダイ開口部に磁場を形成する、 磁性材料か らなる着磁ヨークであって、 2. A magnetized yoke made of a magnetic material which is arranged close to a molding cavity or die opening of a plastic magnet to form a magnetic field in the molding cavity or die opening,
着磁ヨークの幅方向断面内で、 成形キヤビティもしくはダイ開口部に最も近接 して位置する狭幅突部の少なくとも一方側に、 狭幅突部から遠ざかるにつれて、 傾向的に成形キヤビティもしくはダイ開口部から離隔する後退部分を設けてなる 着磁ヨーク。  Within the cross section in the width direction of the magnetized yoke, at least on one side of the molding cavity or the narrow protrusion located closest to the die opening, the molding cavity or the die opening tends to increase as the distance from the narrow projection increases. A magnetized yoke with a receding portion separated from the magnet.
3 . 前記後退部分を、 傾斜面状の後退部分またはステップ状の後退部分としてな る請求の範囲第 2項に記載の着磁ョーク。  3. The magnetized shock according to claim 2, wherein the retreating portion is an inclined surface-like retreating portion or a step-like retreating portion.
4 . シャフトの外周に、 樹脂バインダに磁性粉体を混合分散した樹脂材料よりな る複数の棒状のマグネットピースを、 周方向に隣接させて、 円柱状に形成され、 円柱の周面上に、 軸方向に延在する磁極を複数極有するシャフト付マグネット口 ーラの製造方法において、  4. On the outer periphery of the shaft, a plurality of rod-shaped magnet pieces made of a resin material obtained by mixing and dispersing magnetic powder in a resin binder are formed adjacent to each other in the circumferential direction, and formed into a cylindrical shape. In a method for manufacturing a shaft-mounted magnet roller having a plurality of axially extending magnetic poles,
少なくとも一つの上記マグネットピースを、 少なくともその周方向一部分にお いて、 軸方向の両端部の磁力が、 軸方向中央部の磁力よりも低くなるよう着磁し た後、 このマグネットピースを残余のマグネットピースと組み合わせて形成する マグネットロ一ラの製造方法。 After magnetizing at least one of the magnet pieces so that the magnetic force at both ends in the axial direction is lower than the magnetic force at the central portion in the axial direction at least in a part in the circumferential direction, the magnet pieces are removed from the remaining magnet pieces. Forming in combination with pieces Manufacturing method of magnet roller.
5 . 前記複数極の磁極のうち、 互いに隣接し同じ極性を有する少なくとも一対の 反発極を有し、 これらの反発極同士の間の周面に、 磁力がほぼゼロで、 周方向の 磁力分布が平坦なゼロガウス帯を設けたマグネットローラの製造方法であつて、 このゼロガウス帯を含み、 この両側の反発極に隣接する部分を、 軸方向の両端 部の磁力が、 軸方向中央部の磁力よりも低くなるよう着磁する前記マグネットピ ースとする請求の範囲第 4項に記載のマグネットローラの製造方法。  5. Among the plurality of magnetic poles, the magnetic poles have at least a pair of repulsive poles which are adjacent to each other and have the same polarity, and a magnetic force is substantially zero on a peripheral surface between these repulsive poles, and a circumferential magnetic force distribution is provided. A method of manufacturing a magnet roller provided with a flat zero Gaussian band, wherein the magnetic force at both ends in the axial direction is smaller than the magnetic force at the central portion in the axial direction, including the zero Gaussian band, and the portions adjacent to the repulsion poles on both sides. 5. The method for manufacturing a magnet roller according to claim 4, wherein the magnet piece is magnetized so as to be lowered.
6 . 前記ゼロガウス帯を具えたマグネットピースを、 シャフトの外周面に対応す る、 断面湾曲形状に形成され軸方向に延在する内周面の側に前記反発極と逆の極 性を有する磁極を形成し、 内周面に隣接する両側の側面の側に、 それぞれ、 反発 極と同じ極性を有する磁極を形成した後、 このマグネットピースを消磁し、 その後、 マグネットピースの内周面側の対向位置に、 内周面を反発極と逆の極 性に着磁する着磁ヨークを配置し、 両方の前記側面の側の対向位置に、 これら側 面を反発極と同じ極性に着磁する着磁ヨークを配置するとともに、 外周面側の軸 方向両端部分の対向位置に、 これら両端部分にゼロガウス帯と逆の極性の磁力を 加える着磁ヨークを配置して、 軸方向の両端部の磁力が、 軸方向中央部の磁力よ りも低くなるよう着磁する請求の範囲第 5項に記載のマグネットローラの製造方 法。  6. The magnet piece provided with the zero Gaussian band is provided with a magnetic pole having a polarity opposite to that of the repulsion pole on the side of the inner peripheral surface formed in a curved cross section and extending in the axial direction corresponding to the outer peripheral surface of the shaft. After forming magnetic poles having the same polarity as the repulsion poles on the side surfaces on both sides adjacent to the inner peripheral surface, demagnetize this magnet piece, and then opposing the inner peripheral surface side of the magnet piece A magnetizing yoke for magnetizing the inner peripheral surface with the polarity opposite to the repelling pole is arranged at the position, and magnetizing the side surfaces to the same polarity as the repelling pole at opposite positions on both side surfaces. A magnetic yoke is arranged, and a magnetizing yoke for applying a magnetic force having a polarity opposite to that of the zero Gaussian band is arranged at opposite ends of the outer peripheral surface at positions opposed to both ends in the axial direction. Lower than the magnetic force at the axial center. Yo manufacturing how the magnet roller according to claim 5 to be magnetized.
7 . マグネットピースの外周面側の軸方向両端部分の対向位置に配置する前記着 磁ヨークを、 軸方向中央部から遠ざかるにつれてマグネットピースの周面に近接 するよう傾斜させて配置する請求の範囲第 6項に記載のマグネットローラの製造 方法。  7. The magnetized yoke, which is disposed at a position opposite to both ends in the axial direction on the outer peripheral surface side of the magnet piece, is inclined so as to be closer to the peripheral surface of the magnet piece as the distance from the central portion in the axial direction increases. 7. The method for manufacturing a magnet roller according to item 6.
PCT/JP2002/007073 2001-07-26 2002-07-11 Method for molding plastic magnet and magnetizing yoke used for it, and method for manufacturing magnet roller WO2003011558A1 (en)

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