WO2013118829A1 - Fraise à embout sphérique à bords multiples - Google Patents

Fraise à embout sphérique à bords multiples Download PDF

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Publication number
WO2013118829A1
WO2013118829A1 PCT/JP2013/052895 JP2013052895W WO2013118829A1 WO 2013118829 A1 WO2013118829 A1 WO 2013118829A1 JP 2013052895 W JP2013052895 W JP 2013052895W WO 2013118829 A1 WO2013118829 A1 WO 2013118829A1
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WIPO (PCT)
Prior art keywords
blade
ball
medium
end mill
low gradient
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PCT/JP2013/052895
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English (en)
Japanese (ja)
Inventor
真二郎 堺
英典 熊谷
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日立ツール株式会社
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Publication of WO2013118829A1 publication Critical patent/WO2013118829A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23C—MILLING
    • B23C5/00—Milling-cutters
    • B23C5/02—Milling-cutters characterised by the shape of the cutter
    • B23C5/10—Shank-type cutters, i.e. with an integral shaft
    • B23C5/1009—Ball nose end mills
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23C—MILLING
    • B23C2210/00—Details of milling cutters
    • B23C2210/08—Side or top views of the cutting edge
    • B23C2210/084—Curved cutting edges

Definitions

  • the present invention relates to a multi-blade ball end mill that has a long service life with little chipping and chipping even when high-feed roughing is performed on hard-to-cut materials such as hardened steel used for various molds.
  • JP 2002-187011 discloses a multi-blade ball end mill with three or more ball blades that eliminates chip pockets near the rotation axis and prevents chip clogging.
  • a ball end mill has been proposed in which the lands of each ball blade are thinned and each ball blade is omitted near the center of rotation.
  • the flank of the ball blade before thinning has a width of zero at the rotation center point O as shown in FIG. .
  • a thinning portion having a flank as shown in FIG. 25 is formed.
  • the width of the flank face of the ball blade is substantially zero at the rotation center point O, and there is substantially no cutting edge.
  • a thin and medium gradient blade having an arcuate portion is not formed on the ball blade adjacent to the rear in the rotational direction by thinning. Therefore, chatter vibration occurs when a large load is applied in the vicinity of the rotation center point O, causing chipping and chipping of the ball blade.
  • Japanese Patent Application Laid-Open No. 2003-225821 is a ball end mill having three or more ball blades, in order to prevent the occurrence of minute chipping and chipping near the rotation center point of the ball blade when performing high-speed feed processing.
  • a multi-blade ball end mill is proposed in which the flank faces of all the ball blades reach the axial center, and a gasche having a V-shaped cross section is formed to the vicinity of the rotation center point.
  • this multi-blade ball end mill does not have a medium or low-gradient blade whose center of rotation is retracted in the axial direction, thus eliminating the chatter vibration problem caused by the cutting load near the center of rotation. Not done.
  • Japanese Patent Application Laid-Open No. 2009-56559 is a ball end mill having two or more ball blades, in which a V-shaped or U-shaped groove section passing through the rotation center point is formed between the ball blades.
  • this ball end mill has no cutting edge in the vicinity of the rotation center point, chatter vibrations are generated by a large load in the vicinity of the rotation center point, and there is a possibility that chipping and chipping occur in the ball blade.
  • Japanese Patent Laid-Open No. 9-267211 proposes a two-blade ball end mill with a V-shaped bottom blade at a tilt angle of 4 ° or more at the nose portion of the ball blade so that it is suitable for high-speed cutting of dies and the like Yes.
  • chatter vibrations are generated by a large load applied near the rotation center point, and there is a possibility that chipping and chipping occur in the ball blade.
  • an object of the present invention is a long-life, multi-blade ball end mill suitable for high-feed roughing of hard-hardened hard materials such as hardened steel, and prevents clogging of chips near the rotation center point. Accordingly, it is an object of the present invention to provide a multi-blade multi-blade ball end mill having three or more blades which has a chip pocket and suppresses the occurrence of chatter vibration, thereby effectively preventing chipping and chipping of the ball blade.
  • the multi-blade ball end mill of the present invention includes a shank portion that rotates about a rotation axis, a cutting blade portion having a ball portion at a tip, and three or more cutting blades formed on the cutting blade portion, each having a ball blade.
  • Middle and low gradient blades extend integrally from the tip of each ball blade to the rotation center point in the vicinity of the rotation center point of the ball portion tip,
  • Each of the medium and low gradient blades has at least an arcuate portion curved backward in the rotational direction,
  • Each of the medium and low gradient blades has an inclination angle ⁇ of 0.5 to 3 ° with respect to the plane perpendicular to the rotation axis so that the rotation center point is located rearward in the rotation axis direction than the connecting portion with the ball blade.
  • each medium and low gradient blade Is inclined at The ratio of the radial length of the arcuate portion in each medium and low gradient blade is 20 to 100%, In each cutting edge, the circumferential width of the flank at the connection point between the medium and low gradient blade and the ball blade is 20 to 80% of the maximum circumferential width of the ball blade, The radial length X (the radial distance between the outer end connected to the ball blade and the rotation center point) of each medium / low gradient blade is 1.25 to 3.75% of the blade diameter D of the cutting blade portion. .
  • Each of the medium and low gradient blades preferably includes an arcuate portion on the rotation center point side and an extension portion of the ball blade extending to the arcuate portion.
  • the ball blade extension may be linear or curved.
  • the arcuate portion and the straight portion are preferably connected smoothly without a bending point, but there may be a bending point between them.
  • the center angle ⁇ of the arcuate portion of each medium and low gradient blade is preferably 20 to 70 °.
  • the ratio (degree of curvature) of the length of the perpendicular line dropped from the apex of the arcuate part of each medium and low gradient blade to the line segment connecting both ends thereof and the length of the line segment is 5 to 40%.
  • the arrangement of the ball blades around the rotation axis may be either equally divided or unequal divided in the circumferential direction, but unequal division is preferred.
  • the medium and low gradient blades extend integrally between the tip of each ball blade and the rotation center point in the vicinity of the rotation center point of the ball portion tip.
  • the blade is inclined at an inclination angle ⁇ of 0.5 to 3 ° with respect to the plane orthogonal to the rotation axis so that the rotation center point is located rearward in the rotation axis direction than the connecting portion with the ball blade.
  • the length X in the radial direction of each medium / low gradient blade when viewed along the rotation axis is 1.25 to 3.75% of the blade diameter D of the cutting edge portion. For this reason, a recess (chip pocket) having a minute width T is formed in the vicinity of the rotation center point of the cutting edge.
  • the medium and low-gradient blades are also involved in the cutting process, so it is possible not only to reduce the large cutting load near the rotation center point O, but also to reduce chip discharge. Can be done automatically.
  • each of the medium and low gradient blades has an arcuate portion that is curved at least rearward in the rotation direction, and therefore has a low cutting resistance even for difficult-to-cut materials.
  • the ratio of the radial length of the arcuate portion in each medium / low gradient blade is as large as 20 to 100%, and the circumferential width of the flank at the connection point between each medium / low gradient blade and each ball blade is also the ball. 20 to 80% of the maximum circumferential width of the blade is large. Therefore, each of the medium and low gradient blades has sufficient rigidity, can suppress chatter vibration even in high-feed rough machining of difficult-to-cut materials, and can prevent the ball blades from being worn early, chipped and chipped.
  • the multi-blade ball end mill of the present invention having such characteristics is suitable for high-feed rough machining of difficult-to-cut materials, and particularly suitable for rough machining of dies made of difficult-to-cut materials.
  • FIG. 1 is a side view showing a four-blade ball end mill according to a first embodiment of the present invention.
  • FIG. 2 is an enlarged front view showing a cutting edge in a ball portion of the four-blade ball end mill of FIG.
  • FIG. 2 is an enlarged view showing a trajectory of a ball blade of the four-blade ball end mill of FIG.
  • FIG. 2 is an enlarged front view showing a medium-low gradient blade of the four-blade ball end mill of FIG.
  • FIG. 5 is an enlarged front view showing a part of FIG. 4 for obtaining the central angle of the arcuate portion of the medium and low gradient blade.
  • FIG. 5 is an enlarged front view showing a part of FIG.
  • FIG. 5 is an enlarged perspective view showing a middle / low gradient blade in FIG.
  • FIG. 5 is a partially enlarged perspective view showing a part of FIG.
  • FIG. 3 is a sectional view taken along line AA in FIG.
  • FIG. 5 (a) is a cross-sectional view taken along line BB of FIG.
  • It is an enlarged front view which shows the medium and low-gradient blade of the four blade ball end mill by 2nd embodiment of this invention.
  • FIG. 10 is an enlarged front view showing a part of FIG. 9 for obtaining the central angle of the arcuate portion of the medium and low gradient blade.
  • FIG. 12 is an enlarged front view showing a part of FIG. 11 for explaining the configuration of the medium-low gradient blade. It is an enlarged front view which shows the ball
  • FIG. 16 is an enlarged front view showing a part of FIG. 15 in order to obtain the radial length of the gradient blade. It is an enlarged front view which shows the cutting edge in the ball
  • FIG. 18 is an enlarged front view showing a part of FIG. 17 in order to obtain the radial length of the gradient blade.
  • 4 is an optical micrograph showing the front of a ball blade of a four-blade ball end mill A that was cut for 90 minutes in Example 2.
  • FIG. 3 is an optical micrograph showing an oblique view of a ball blade of a four-blade ball end mill A that was cut for 90 minutes in Example 2.
  • FIG. 2 is an optical micrograph showing the front of a ball blade of a four-blade ball end mill B subjected to a cutting process for 90 minutes in Example 2.
  • FIG. FIG. 3 is an optical micrograph showing an oblique view of a ball blade of a four-blade ball end mill B that was cut for 90 minutes in Example 2.
  • FIG. 2 is a front view showing a ball blade before thinning in a multi-blade ball end mill disclosed in Japanese Patent Laid-Open No. 2002-187011.
  • FIG. 2 is an enlarged front view showing details of a ball blade after thinning in a multi-blade ball end mill disclosed in Japanese Patent Laid-Open No. 2002-187011.
  • FIG. 3 is a front view showing a four-blade ball end mill described in JP-A-2003-225821.
  • the multi-blade ball end mill of the present invention suitable for high-feed roughing of difficult-to-cut materials with high hardness will be described in detail below using a solid multi-blade ball end mill made of cemented carbide as an example.
  • the number of cutting edges of the multi-blade ball end mill of the present invention is preferably 3 to 6.
  • the term “high hardness difficult-to-cut material” refers to a metal having a Rockwell hardness HRC of 40 or more, particularly 50 or more, such as hardened alloy tool steel (SKD61, SKD11, powder high speed, etc.). Means.
  • the term “roughing” means processing performed before finishing processing, which has a large cutting depth and feed amount in order to increase cutting efficiency, and thus has a large cutting load.
  • the term “high feed machining” means machining in which any one or more of the feed speed Vf, the axial cutting depth ap, and the radial cutting depth ae is increased in order to perform high-efficiency machining.
  • feed rate Vf is 1250 mm / min or more
  • axial cutting depth ap is 0.3 mm or more
  • radial cutting depth ae is 0.9 mm or more.
  • the feed rate Vf is 1500 mm / min or more
  • the axial cutting depth ap is 0.4 mm or more
  • the radial cutting depth ae is 1.2 mm or more.
  • Solid-type multi-blade ball end mill made of cemented carbide is a mixture of WC powder and Co powder, which is molded and sintered, and then finished with cutting edges, gashes, chip discharge grooves, flank surfaces, rake surfaces, etc. Manufactured by (grinding). If necessary, a known wear-resistant hard coating such as TiSiN, TiAlN, TiAlSiN, CrN, CrSiN, AlCrN, AlCrSiN, AlTiCrN, or AlCrVBN is coated on the cutting edge portion.
  • a known wear-resistant hard coating such as TiSiN, TiAlN, TiAlSiN, CrN, CrSiN, AlCrN, AlCrSiN, AlTiCrN, or AlCrVBN is coated on the cutting edge portion.
  • FIGS. 1 to 5 Four-flute ball end mill (1)
  • First Embodiment A four-blade ball end mill 1 according to a first embodiment of the present invention shown in FIGS. 1 to 5 includes a cylindrical shank portion 2 and a cutting edge portion 3.
  • the cutting edge portion 3 includes a ball portion 3a at the tip, and an outer peripheral blade portion 3b between the ball portion 3a and the shank portion 2.
  • the cutting blade portion 3 is formed with four cutting blades 5a, 5b, 5c, 5d having a predetermined twist angle, and each cutting blade 5a to 5d is an arcuate ball blade 6a formed on the ball portion 3a. , 6b, 6c, 6d and spiral outer peripheral blades 7a, 7b, 7c, 7d formed on the outer peripheral blade portion 3b.
  • Each of the ball blades 6a-6d and each of the outer peripheral blades 7a-7d is smooth (bending point). Without connection). As shown in FIG. 2, four ball blades 6a to 6d are arranged around the rotation center point O through the gashes 17a to 17d in the ball portion 3a.
  • rake surfaces 11a to 11d are formed in front of the ball blades 6a to 6d in the rotational direction, and relief surfaces (lands) 9a, 9b, 9c and 9d are formed in the rear in the rotational direction.
  • relief surfaces (lands) 9a, 9b, 9c and 9d are formed in the rear in the rotational direction.
  • gashes 17a to 17d are formed in front of the rake faces 11a to 11d in the rotation direction, and the gashes 17a to 17d are in contact with the chip discharge grooves 4.
  • Ball blades 6a to 6d (only 6a and 6c are visible in FIG. 3) are points P1, P2, P3, and P4 near the rotation center point O from the outer periphery of the cutting edge 3 (only P1 and P3 are visible in FIG. 3). It extends to.
  • Middle and low gradient blades 8a, 8b, 8c, and 8d extend between the points P1 to P4 and the rotation center point O.
  • the points P1 to P4 can be called the tips of the ball blades 6a to 6d, the outer ends of the medium / low gradient blades 8a to 8d, or the connection points of the ball blades 6a to 6d and the medium / low gradient blades 8a to 8d.
  • Relief surfaces 10a, 10b, 10c, and 10d are formed at the rear in the rotational direction of the medium and low gradient blades 8a to 8d.
  • Each flank 10a to 10d is connected to the corresponding ball blade flank 9a to 9d via boundary lines 15a, 15b, 15c and 15d.
  • the medium and low gradient blades 8a to 8d extend from the rotation center point O to the respective points K1 to K4 and rotate. It consists of an arcuate portion curved backward in the direction and a ball blade extension extending from each point K1 to K4 to each point P1 to P4.
  • the arcuate portion is represented by 8d1
  • the ball blade extension portion is represented by 8d2.
  • R represents the direction of rotation.
  • the arcuate portion 8d1 of the medium / low gradient blade 8d is formed by forming the flank 10a of the medium / low gradient blade 8a adjacent to the front in the rotational direction. The same applies to the other arcuate portions 8a1 to 8c1.
  • the arcuate portions 8a1 to 8c1 may be entirely curved or may be partially curved. In the latter case, since the curved portion and the straight portion are smoothly connected, the boundary between the two is not determined accurately. Therefore, whether the curved portion is entire or partial, it will be referred to as an “arch”.
  • each of the medium and low gradient blades 8a to 8d may be an arcuate portion that is curved backward in the rotation direction.
  • the medium and low gradient blades 8a to 8d since each of the medium and low gradient blades 8a to 8d has the arcuate portions 8a1 to 8d1 curved at least in the rearward direction of rotation, the medium and low gradient blades can be used in the high feed cutting process that also uses the medium and low gradient blades 8a to 8d. 8a-8d can withstand cutting loads.
  • the flank 10a of the medium / low gradient blade 8a is in curved contact with the medium / low gradient blade 8d behind the rotation direction, and the medium / low gradient blade 8d And the trailing edge of the flank 10a in the rotational direction is connected to the gash 17d.
  • each of the medium and low gradient blades 8a to 8d is inclined at a slight inclination angle ⁇ with respect to the plane orthogonal to the rotation axis Ax so that the rotation center point O is the last point in the rotation axis direction. ing.
  • the medium / low gradient blades 8a to 8d located inside the tips P1 to P4 of the ball blades 6a to 6d form a very shallow recess 13 having a minute width T.
  • the recess 13 is represented by a circle C centered on the rotation center point O and passing through the connection points P1 to P4 of the medium and low gradient blades 8a to 8d and the ball blades 6a to 6d.
  • the inclination angle ⁇ of each of the medium and low gradient blades 8a to 8d is 0.5 to 3 °. If the inclination angle ⁇ exceeds 3 °, the cutting edges near the points P1 to P4 (ball blades 6a to 6d and medium to low gradient blades 8a 8d end) is likely to be prematurely worn and chipped. When the inclination angle ⁇ is smaller than 0.5 °, the medium and low gradient blades 8a to 8d near the rotation center point O are likely to come into contact with the work material, and the effect of the medium and low gradient blades 8a to 8d to reduce cutting resistance is achieved. Disappear.
  • a preferable inclination angle ⁇ is 1 to 2 °. As described above, since each of the medium and low gradient blades 8a to 8d is inclined rearward in the rotation axis direction with a minute inclination angle, chatter vibration can be suppressed in high feed cutting.
  • the radial length X of the medium and low gradient blades 8a to 8d is 1.25 to 3.75% of the blade diameter D of the cutting edge portion 3.
  • the radial length X of the medium and low gradient blades 8a to 8d is the radial distance between the outer ends P1 to P4 connected to the ball blades 6a to 6d and the rotation center point O, as seen from the front view of the cutting blade portion 3. Is equal to the distance between the outer ends P1 to P4 and the rotation center point O.
  • the radial length X of each of the medium and low gradient blades 8a to 8d (the radial distance between the outer ends P1 to P4 connected to the ball blades 6a to 6d and the rotation center point O) is Half the width T.
  • the width T of the recess 13 is set in the range of 0.2 to 0.6 mm.
  • the inclination angle ⁇ of the medium and low-gradient blades at the point O and the vicinity thereof can be secured in the range of 0.5 to 3 °, thereby enabling highly efficient roughing. If the radial length X of the medium / low gradient blades 8a to 8d is less than 1.25% of the blade diameter D of the cutting edge part 3, the inclination angle ⁇ of the medium / low gradient blades 8a to 8d becomes too large, and the medium / low gradient blade Processing of 8a to 8d is difficult.
  • the radial length X of the medium and low gradient blades 8a to 8d is more than 3.75% of the blade diameter D of the cutting edge, the ball blades 6a to 6d will be too short compared to the medium bottom gradient blades 8a to 8d. High-efficiency, high-feed cutting cannot be realized.
  • the radial length X of the medium / low gradient blades 8a to 8d is preferably 1.5 to 3.5% of the blade diameter D of the cutting edge portion 3.
  • the blade diameter D is preferably 0.1 to 30 mm, more preferably 0.5 to 20 mm from the viewpoint of practicality.
  • the medium / low gradient blade 8d has an arcuate portion 8d1 extending from the rotation center point O to the point K4.
  • the ball blade extension 8d2 extending from the point K4 to the outer end P4, the radial length X of the medium / low gradient blade 8d is equal to the radial length X1 of the arcuate portion 8d1 and the ball blade extension. This is the sum of the radial length X2 of 8d2.
  • the ball blade extension 8d2 is linear, but may be curved. The same applies to the other medium and low gradient blades 8a to 8c.
  • the radial length X1 of the arcuate portion is 20 to 100%, preferably 30 to 100%, more preferably 60 to 100% of the radial length X of the medium and low gradient blades 8a to 8d.
  • X1 is less than 20% of X, the cutting resistance of the medium and low gradient blades 8a to 8d is large.
  • the line segment Q1- Position point Q1 so that the length of Q2 is maximized.
  • the ratio of the length of the line segment Q1-Q2 and the length of the line segment L3 at that time is defined as the curvature of the arcuate portion 8d1 of the medium / low gradient blade 8d.
  • the ratio (curvature) between the length of the line segment Q1-Q2 and the length of the line segment L3 is preferably 5 to 40%, more preferably 8 to 35%. If the degree of curvature is less than 5%, the tip pocket is too small, and if it exceeds 40%, the rigidity of the medium / low gradient blade is insufficient.
  • the hollow portion 13 having a small width T formed near the rotation center point O of the ball portion 3a is connected to the gashes 17a to 17d and functions as a tip pocket at the tip of the cutting edge portion 3.
  • the extremely thin chips generated by the medium and low-gradient blades 8a to 8d are discharged from the recess 13 to the chip discharge groove 4 via the gashes 17a to 17d, preventing chip clogging near the rotation center point O even in high-feed cutting. it can.
  • the width of the flank faces 10a to 10d of each medium and low gradient blade varies between the boundary lines 15a to 15d and the rotation center point O. Therefore, the widths of the flank surfaces 10a to 10d are evaluated by the following method. As illustrated in FIG. 7, the circumferential width W1 at the point P1 of the flank 10a of the medium / low gradient blade 8a is 20 to 80% of the maximum circumferential width W2 of the ball blade 6a, preferably 30 to 70%. By satisfying this requirement, the medium / low gradient blade can ensure high rigidity.
  • the circumferential width W1 of the flank 10a of the medium / low-gradient blade 8a at the point P1 connects the points P1 and P1 ′ at which the circle C passing through the point P1 with the rotation center point O as the center intersects the flank 10a. It is the length of the straight line.
  • the maximum circumferential width W2 of the ball blade 6a is the length of a straight line connecting the points B and B ′ where the circle C ′ centering on the rotation center point O intersects the flank 9a of the ball blade 6a (straight line Set the radius of the circle C 'so that the length of B-B' is maximized.).
  • the central angle ⁇ of the arcuate portions 8a1 to 8d1 of the medium and low gradient blades 8a to 8d is used.
  • the central angle ⁇ of the arcuate portions 8a1 to 8d1 is equal to both ends of the arcuate portion 8c1 of the medium / low gradient blade 8c formed by forming the flank 10d of the medium / low gradient blade 8d, as illustrated in FIG. 5 (a).
  • the center angle ⁇ of the arcuate part of the medium / low gradient blade is preferably 20 to 70 °. If the central angle ⁇ is less than 20 °, the width of the flank faces 10a to 10d of the medium and low gradient blades 8a to 8d is too small, and sufficient rigidity against the load resistance during cutting cannot be obtained. On the other hand, the medium and low gradient blades having a central angle ⁇ of 70 ° while satisfying the condition that the radial length X of each of the medium and low gradient blades 8a to 8d is 1.25 to 3.75% of the blade diameter D of the cutting edge portion 3. It is difficult to form 8a to 8d.
  • the central angle ⁇ is more preferably 30 to 60 °, and most preferably 40 to 48 °.
  • each of the medium and low gradient blades 8a to 8d not only has an arcuate portion curved at the rear in the rotation direction, but also has sufficient rigidity because the flank surfaces 10a to 10d have a sufficient width. For this reason, even when the roughing of the work material is performed at a high feed rate, chipping and chipping of the medium / low gradient blades 8a to 8d can be effectively prevented.
  • each of the ball blades 6a to 6d has a negative rake angle ⁇ 1
  • each of the medium and low gradient blades 8a to 8d has a negative rake angle ⁇ 2.
  • ⁇ 1 and ⁇ 2 may have a positive rake angle.
  • ⁇ 1 and ⁇ 2 are defined as rake angles in the direction orthogonal to the rotation axis Ax.
  • the rake angle ⁇ 1 of the ball blade 6d is preferably ⁇ 30 ° to 0 °.
  • the rake angle ⁇ 2 of the medium / low gradient blade 8d is preferably ⁇ 30 ° to 0 °.
  • both ⁇ 1 and ⁇ 2 are less than ⁇ 30 °, the cutting resistance becomes excessive, and if it exceeds 0 °, the design conditions become severe.
  • the ball blades 6a to 6d and the medium / low gradient blades 8a to 8d have sufficient rigidity, and in particular, the medium and low gradient blades 8a to 8d thinner than the ball blades 6a to 6d also have sufficient rigidity. Secured. As a result, chipping and chipping can be prevented in the case of high-efficiency roughing.
  • the clearance angles of the clearance surfaces 9a to 9d of the ball blades 6a to 6d and the clearance angles of the clearance surfaces 10a to 10d of the medium and low gradient blades 8a to 8d are preferably within 7 to 21 °.
  • both clearance angles are less than 7 °, the cutting resistance is high, and chatter vibration is likely to occur in highly efficient cutting.
  • both clearance angles exceed 21 ° the cutting resistance is reduced, but the rigidity of the ball blade and the medium / low gradient blade is reduced, so that chipping and chipping are likely to occur in highly efficient cutting.
  • the clearance angle of the flank faces 9a to 9d of the ball blade and the clearance angle of the flank faces 10a to 10d of the medium / low gradient blade are both preferably 9 to 19 °, and most preferably 10 to 15 °. Note that these clearance angles are preferably substantially the same. Accordingly, even when high-efficiency roughing is performed on a hard material having high hardness, chipping and chipping of the ball blade and the medium / low gradient blade are effectively prevented, and stable cutting can be performed.
  • the four-blade ball end mill 20 according to the second embodiment of the present invention is substantially the same except that each of the medium and low-gradient blades 8a to 8d consists of only an arcuate portion. Specifically, this is the same as the four-blade ball end mill 1 according to the first embodiment.
  • the same reference numerals are assigned to the same parts as those in the first embodiment. Therefore, only the shapes of the medium and low gradient blades 8a to 8d will be described in detail below.
  • the arcuate portion is entirely curved, but of course, the arcuate portion may partially include a linear portion.
  • the outer end P4 of the medium / low gradient blade 8d and the outer end K4 of the arcuate portion 8d1 coincide.
  • the circumferential width W1 at the point P4 of the flank 10d of the medium / low gradient blade 8d is 20 to 80% of the maximum circumferential width W2 of the ball blade 6d, as in the first embodiment. .
  • a straight line L2 is drawn between the two to obtain the central angle ⁇ of the arcuate portion.
  • the central angle ⁇ of the arcuate portion is preferably 20 to 70 ° as in the first embodiment.
  • the four-blade ball end mill 30 according to the third embodiment of the present invention includes (a) an arcuate portion and a curved portion connected via a bending point. This is substantially the same as the four-blade ball end mill 1 according to the first embodiment except that (b) the ball blade is non-uniformly divided.
  • the same reference numerals are assigned to the same parts as those in the first embodiment. Therefore, only the differences will be described in detail below.
  • Fig. 12 shows a part of Fig. 11 on an enlarged scale.
  • the arcuate portion 8c1 formed when forming the flank 10d extends between the rotation center point O and the point K3, and the curved extension portion 8c2 extending radially inward from the ball blade 6c is arcuate.
  • the part 8c1 is connected to the point K3.
  • the point K3 becomes a bending point between the arcuate portion 8c1 and the curved portion 8c2.
  • the circumferential width W1 at the point P4 of the flank 10d of the medium / low gradient blade 8d is 20 to 80 of the maximum circumferential width W2 of the ball blade 6d, as in the first embodiment. %.
  • the central angle ⁇ of the arcuate portion 8c1 of the medium / low gradient blade 8c formed by the formation of the flank 10d of the medium / low gradient blade 8d is a straight line L1 connecting both ends O and K3 of the arcuate portion 8c1 and the point P4. , The angle formed by L2.
  • the central angle ⁇ of the arcuate portion is preferably 20 to 70 ° as in the first embodiment.
  • the ball blades are unevenly divided, the positions and widths of the ball blades 6a to 6d are different, and the medium and low gradient blades 8a to 8d and the flank surfaces 10a to 10d are also different.
  • Such unevenly divided ball blades further suppress chatter vibration in the case of high-feed roughing of difficult-to-cut materials with high hardness.
  • the thin disc-shaped diamond grindstone that reciprocates in the direction E with respect to the flank 9d of one ball blade (for example, 6d) is gradually lowered to the direction of the arrow F from the point P4. Move to. As a result, a flank 10d that inclines backward from the point P4 in the rotation axis direction is formed.
  • the direction E In order to avoid interference with the ball blade 6c of another flank 9c against which the flank 9d abuts, the direction E must be inclined with respect to the ball blade 6c.
  • the inclination angle in the direction E with respect to the ball blade 6c may be 20 to 50 °.
  • the inclination angle is less than 20 °, the accuracy of the grinding process decreases, and if it exceeds 50 °, the grinding wheel interferes.
  • the medium and low gradient blades 8a to 8d shown in FIG. 11 are formed.
  • FIGS. 15 and 16 show the arrangement of medium and low gradient blades in the three-blade ball end mill 40 of the present invention.
  • the three-blade ball end mill 40 is composed of three ball blades 6a, 6b, 6c and medium-low extending integrally from the end portions P1, P2, P3 of the ball blades 6a, 6b, 6c to the rotation center point O.
  • Gradient blades 8a, 8b, and 8c are provided.
  • Gash 17a, 17b and 17c are formed in front of the ball blades 6a, 6b and 6c in the rotational direction.
  • the medium / low-gradient blade 8a includes an arcuate portion 8a1 that is curved backward in the rotation direction, and a ball blade extension portion 8a2.
  • the ball blade extension portion 8a2 may not be provided, and the arcuate portion 8a1 does not have to be entirely curved, and may be composed of a curved portion and a straight portion. This also applies to the other medium and low gradient blades 8b, 8c.
  • each of the medium and low-gradient blades 8a, 8b, 8c is arranged such that the rotation center point O is located rearward in the rotation axis direction than the connecting portions P1, P2, P3 with the ball blades 6a, 6b, 6c. Further, it is inclined at an inclination angle ⁇ of 0.5 to 3 ° with respect to a plane orthogonal to the rotation axis.
  • the ratio of the radial length X1 of the arcuate portion 8a1 to the radial length X of the medium and low gradient blade 8a is 20 to 100%, as in the first embodiment.
  • the circumferential width W1 of the flank 10a at the connection point P1 between the medium / low-gradient blade 8a and the ball blade 6a is 20 to 80% of the maximum circumferential width of the ball blade and is seen along the rotation axis.
  • the length X in the radial direction of the medium and low gradient blade 8a (the radial distance between the outer end P1 connected to the ball blade 6a and the rotation center point O) is 1.25 to 3.75% of the blade diameter D of the cutting edge portion 3.
  • the central angle ⁇ of the arcuate portion of the medium / low gradient blade 8a is preferably 20 to 70 °, as in the first embodiment.
  • FIGS. 17 and 18 show the arrangement of medium and low gradient blades in the six-blade ball end mill 50 of the present invention.
  • the six-blade ball end mill 50 is integrally formed from six ball blades 6a, 6b, 6c, 6d, 6e, 6f and ends P1, P2, P3, P4, P5, P6 of each ball blade 6a to 6f. It has medium and low gradient blades 8a, 8b, 8c, 8d, 8e, 8f extending to the rotation center point O. Gashes 17a, 17b, 17c, 17d, 17e, and 17f are formed in front of the ball blades 6a to 6f in the rotation direction.
  • the medium / low-gradient blade 8a includes an arcuate portion 8a1 that is curved backward in the rotation direction and a ball blade extension portion 8a2.
  • the ball blade extension portion 8a2 may not be provided, and the arcuate portion 8a1 does not have to be entirely curved, and may be composed of a curved portion and a straight portion. This also applies to the other medium and low gradient blades 8b-8f.
  • each of the medium and low-gradient blades 8a to 8f is orthogonal to the rotation axis so that the rotation center point O is positioned rearward in the rotation axis direction from the connecting portions P1 to P6 with the ball blades 6a to 6f. It is inclined at an inclination angle ⁇ of 0.5 to 3 ° with respect to the surface.
  • the ratio of the radial length X1 of the arcuate portion 8a1 to the radial length X of the medium / low gradient blade 8a is 20 to 100%, as in the first embodiment.
  • the circumferential width W1 of the flank 10a at the connection point P1 between the medium / low-gradient blade 8a and the ball blade 6a is 20 to 80% of the maximum circumferential width of the ball blade, as in the first embodiment.
  • the radial length X of the medium / low gradient blade 8a when viewed along the rotation axis (radial distance between the outer end P1 connected to the ball blade 6a and the rotation center point O) is also the same as that of the first embodiment.
  • the central angle ⁇ of the arcuate portion of the medium / low gradient blade 8a is preferably 20 to 70 ° as in the first embodiment.
  • Example 1 The four-blade ball end mill A according to the present invention having the shape shown in FIGS. 1 to 4 and the four-blade ball end mill B described in JP-A-2009-56559 (ball portion near the rotation center point) The tip region has two grooves crossing the cross). All have equally divided cutting edges. Table 1 shows the size of each 4-flute ball end mill.
  • Ratio of radial length X1 of arcuate part to radial length X of medium and low gradient blades (%).
  • Each four-flute ball end mill was mounted on an NC-controlled three-axis machining center, and a workpiece made of SKD61 (alloy tool steel) having a Rockwell hardness of HRC 50 was cut into a plane under the following cutting condition 1.
  • the medium and low gradient blades were also observed for defects and chipping, and VBmax was measured.
  • the wear width is an average value of VBmax of the flank faces of the four ball blades.
  • Cutting condition 1 Cutting method: Dry surface cutting using air blow Cutting speed Vc: 94 m / min Number of revolutions n: 3750 min -1 Feed rate Vf: 1500 mm / min Feed per tooth fz: 0.1 mm / tooth axial depth of cut ap: 0.7 mm Radial cutting depth ae: 1.75 mm Tool overhang OH: 32 mm
  • the four blade ball end mill A of the present invention since the medium and low gradient blades connected to the ball blade with a small inclination angle are also involved in the cutting process, the cutting process can proceed in a stable state, An excessive cutting load is not applied to the end of the ball blade, and chatter vibration is suppressed. Further, the four-blade ball end mill A of the present invention has a wear width of the ball blade by cutting for 90 minutes is about 1/2 of that of the four-blade ball end mill B, and can be determined to have a long life.
  • Example 2 Four-blade ball end mill C shown in FIG. 9 and four-blade ball end mill described in JP-A-2009-56559 under the same conditions as in Example 1 except that OH / D was changed to 6 and cutting condition 2 was used Using B, a pocket on a standing wall of a workpiece made of YXR3 (registered trademark) with a Rockwell hardness HRC of 58 (length: 25 mm, width: 25 mm, height: 14.7 mm) is cut for 90 minutes. did.
  • YXR3 is a steel type used for cold forging dies.
  • Cutting condition 2 Cutting method: Dry cutting of standing wall pocket using air blow Cutting speed Vc: 38 m / min Number of revolutions n: 1500 min -1 Feed rate Vf: 225 mm / min Feed per tooth fz: 0.075 mm / tooth axial depth of cut ap: 0.35 mm Radial depth of cut ae: 1.23 mm Tool overhang OH: 48 mm
  • FIGS. 19 (a) and 19 (b) The results of cutting using the four-blade ball end mill C of the present invention are shown in FIGS. 19 (a) and 19 (b), and the results of cutting using the four-blade ball end mill B are shown in FIG. 20 (a). And it is shown in FIG. 20 (b).
  • FIG. 19 and FIG. (a) As shown in FIGS. 19 (a) and 19 (b), in the four-blade ball end mill C of the present invention, the wear width of the flank face of the ball blade is as small as 0.07 mm even after 90 minutes, and normal wear. It was in the range.
  • FIGS. 19 (a) and 19 (b) As shown in FIGS.
  • Example 3 Using the above-described four-fluid ball end mills A and B, an inclined surface (an inclination angle of 30 °) of the workpiece made of YXR3 (registered trademark) was cut under the same cutting condition 2 as in Example 2. In the cutting of the inclined surface, the ball blade near the rotation center point O was also involved in the cutting. As a result of cutting for 90 minutes, in the four-blade ball end mill A of the present invention, the wear, chipping, and chipping to the extent that the processing accuracy is affected to the ball blade and the medium / low gradient blade were not recognized. On the other hand, chipping similar to that shown in FIG. 20 (b) was observed on the ball blade of the four-blade ball end mill B. Since the four-flute ball end mill B does not have a medium or low-gradient blade, it can be assumed that chatter vibration was generated by a large cutting load applied near the rotation center point O, which caused chipping of the ball blade.
  • chatter vibration was generated by a large cutting load applied near
  • Example 4 Four-blade ball end mill A of the present invention and Japanese Patent Application Laid-Open No. 2003-225821 shown in FIG. 26 under the same conditions as in Example 1 except that OH / D is 7 and the work material is SKD11 with an HRC of 60. Using the four-blade ball end mill D (equal division) described in 1 above, the workpiece was subjected to plane cutting under the following cutting condition 3.
  • Cutting condition 3 Cutting method: Dry surface cutting using air blow Cutting speed Vc: 94 m / min Number of revolutions n: 3750 min -1 Feed rate Vf: 1500 mm / min Feed per tooth fz: 0.1 mm / tooth axial depth of cut ap: 0.7 mm Radial cutting depth ae: 1.75 mm Tool overhang OH: 56 mm
  • the chipping and chipping of the ball blade and the medium / low gradient blade were observed by cutting for 40 seconds (cutting distance: 1 mm). As a result, no chipping or chipping was observed on the ball blade and the medium / low gradient blade of the four-blade ball end mill A, but chipping was observed on the ball blade of the four-blade ball end mill D.
  • the reason why chipping occurred in the 4-flute ball end mill D at the beginning of cutting is that the ball blade extends to the rotation center point O. It can be inferred that the vibration is generated and the cutting load acting on the ball blade is uneven due to chatter vibration. On the other hand, in the four-blade ball end mill A, it is considered that the occurrence of chatter vibration was suppressed by the medium-low gradient blade.
  • Example 5 YXR3 (registered trademark) with an HRC of 58 using a four-flute ball end mill A ′ shown in FIG. 11 (the cutting edges are arranged in an irregular division of 4 ° in the circumferential direction around the rotation center point O) ) After cutting the workpiece in a straight line under the following cutting condition 5, cut the corner that bends 90 ° on the plane, and then repeat the cutting in a straight line again. went. In the case of 4 ° unequal division, the arrangement angles of the four ball blades are 86 °, 94 °, 86 °, and 94 ° in this order. Table 3 shows the main specifications of the ball end mill A '. FIG.
  • FIG. 21 shows the results of evaluating chatter vibration using a three-component waveform of cutting resistance.
  • the vertical axis in FIG. 21 is component force [N], and the horizontal axis is Time [S].
  • Cutting condition 5 Cutting method: Dry surface cutting using air blow Cutting speed Vc: 100 m / min Rotational speed n: 4000 min -1 Feed rate Vf: 1920 mm / min Feed per tooth fz: 0.12 mm / tooth axial depth of cut ap: 0.3 mm Radial cutting depth ae: 0.1 mm Tool overhang OH: 32 mm
  • Ratio of radial length X1 of arcuate part to radial length X of medium and low gradient blades (%).
  • Example 6 The cutting performance of the ball end mills E to M in which the specifications of the ball end mill A ′ used in Example 5 were changed as shown in Table 4 were evaluated.
  • Ball end mills E to L are within the scope of the present invention, and ball end mill M is outside the scope of the present invention.
  • the specifications not described in Table 4 were the same as the ball end mill A ′ used in Example 5.
  • Cutting conditions were set to cutting conditions 5 as in Example 5, and chatter vibration was evaluated using a three-component force waveform of cutting resistance as in the ball end mill A ′.
  • Table 4 shows the evaluation results (presence / absence of chatter vibration). Note: (1) Ratio of radial length X1 of arcuate part to radial length X of medium and low gradient blades (%). (2) The ratio between the circumferential width W1 and the maximum circumferential width W2 of the ball blade at the connection point P between the flank of the medium and low gradient blade and the ball blade.

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Abstract

La fraise à embout sphérique à bords multiples selon l'invention est équipée d'une partie de queue, d'une partie de bord de coupe comprenant une partie sphérique et d'au moins trois bords de coupe comprenant chacun un bord sphérique. La fraise selon l'invention comprend : des bords inclinés concaves s'étendant d'un seul bloc depuis les pointes de chaque bord sphérique à proximité du centre de rotation de la pointe de la partie sphérique aussi loin que le centre de rotation ; chaque bord incliné concave comprenant une section en forme d'arc qui est au moins incurvée vers l'arrière dans la direction de rotation ; chaque partie inclinée concave étant inclinée selon un angle d'inclinaison (α) de 0,5-3° par rapport au plan perpendiculaire à l'axe de rotation, de sorte que le centre de rotation soit situé vers l'arrière dans la direction de l'axe de rotation ; le pourcentage, dans la direction radiale, de la longueur de la section en forme d'arc dans chacune des parties inclinées concaves étant de 20-100 % ; dans chacun des bords de coupe, la largeur, dans la direction circonférentielle, de la surface de la face de dépouille au niveau du point de raccordement entre le bord incliné concave et le bord sphérique représentant 20-80 % de la largeur maximale, dans la direction circonférentielle, du bord sphérique ; et la longueur (X), dans la direction radiale, de chacun des bords inclinés concaves représentant 1,25-3,75 % du diamètre de coupe (D) de la partie de bord de coupe.
PCT/JP2013/052895 2012-02-07 2013-02-07 Fraise à embout sphérique à bords multiples WO2013118829A1 (fr)

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US20140003873A1 (en) * 2011-02-16 2014-01-02 Hitachi Tool Engineering, Ltd. End mill for cutting of high-hardness materials
CN105473264A (zh) * 2013-10-23 2016-04-06 三菱综合材料株式会社 球头立铣刀
WO2016067985A1 (fr) * 2014-10-28 2016-05-06 三菱日立ツール株式会社 Fraise cylindrique deux tailles en céramique et procédé de coupe de matériau difficile à couper à l'aide de celle-ci
GB2542124A (en) * 2015-09-08 2017-03-15 Technicut Ltd Method and tools for manufacturing a blisk
JP2019202378A (ja) * 2018-05-23 2019-11-28 三菱日立ツール株式会社 エンドミル

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JP2021115684A (ja) * 2020-01-28 2021-08-10 日進工具株式会社 多刃ボールエンドミル及び多刃ボールエンドミルの加工方法
JP7417707B2 (ja) 2020-02-28 2024-01-18 京セラ株式会社 エンドミル及び切削加工物の製造方法

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US20140003873A1 (en) * 2011-02-16 2014-01-02 Hitachi Tool Engineering, Ltd. End mill for cutting of high-hardness materials
US9421624B2 (en) * 2011-02-16 2016-08-23 Hitachi Tool Engineering, Ltd. End mill for cutting of high-hardness materials
CN105473264A (zh) * 2013-10-23 2016-04-06 三菱综合材料株式会社 球头立铣刀
US10449611B2 (en) 2013-10-23 2019-10-22 Mitsubishi Materials Corporation Ball end mill
CN107073602A (zh) * 2014-10-28 2017-08-18 三菱日立工具技术株式会社 陶瓷立铣刀以及使用该陶瓷立铣刀的难切削材料的切削方法
JPWO2016067985A1 (ja) * 2014-10-28 2017-09-07 三菱日立ツール株式会社 セラミックスエンドミル及びそれを用いた難削材の切削方法
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CN107073602B (zh) * 2014-10-28 2019-03-15 三菱日立工具技术株式会社 陶瓷立铣刀以及使用该陶瓷立铣刀的难切削材料的切削方法
WO2016067985A1 (fr) * 2014-10-28 2016-05-06 三菱日立ツール株式会社 Fraise cylindrique deux tailles en céramique et procédé de coupe de matériau difficile à couper à l'aide de celle-ci
WO2017042158A1 (fr) * 2015-09-08 2017-03-16 Technicut Limited Procédé et outil pour l'usinage d'un disque monobloc
GB2542124A (en) * 2015-09-08 2017-03-15 Technicut Ltd Method and tools for manufacturing a blisk
GB2542124B (en) * 2015-09-08 2019-06-05 Technicut Ltd Method and tools for manufacturing a bladed disk
JP2019202378A (ja) * 2018-05-23 2019-11-28 三菱日立ツール株式会社 エンドミル
JP7089171B2 (ja) 2018-05-23 2022-06-22 株式会社Moldino エンドミル

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