Cutting tool for milling and cutting tool for turning

Abstract

This cutting tool for milling has a cutting insert and a body. The cutting insert is attached to the body. The body is rotatable around an axis of rotation. The cutting insert includes a base member and a cutting member joined to the base member. The cutting member has a main cutting edge part. The cutting insert has a placement surface attached to the body and an upper surface opposite to the placement surface. When viewed in a direction perpendicular to the upper surface, an angle formed by a reference straight line perpendicular to the axis of rotation and a joint part between the base member and the cutting member is 5° or more and 20° or less. When viewed in a direction perpendicular to the upper surface, an angle formed by the reference straight line and the main cutting edge part is 5° or more and 20° or less.

Description

Milling and turning tools

[0001] The present disclosure relates to milling and turning cutting tools.

[0002] Japanese Patent Laid-Open Publication No. 8-141822 (Patent Document 1) discloses a throw-away insert for a milling cutter having a base metal made of cemented carbide and a cutting edge made of cubic boron nitride sintered body.

[0003] Japanese Patent Application Publication No. 8-141822

[0004] The milling cutting tool according to the present disclosure includes a cutting insert and a body. The cutting insert is attached to the body. The body is rotatable around a rotation axis. The cutting insert includes a base member and a cutting member joined to the base member. The cutting member has a major cutting edge portion. The cutting insert has a mounting surface attached to the body and an upper surface opposite the mounting surface. When viewed in a direction perpendicular to the upper surface, an angle formed between a reference line perpendicular to the rotation axis and a joint between the base member and the cutting member is 5° or more and 20° or less. When viewed in a direction perpendicular to the upper surface, an angle formed between the reference line and the major cutting edge portion is 5° or more and 20° or less.

[0005] FIG. 1 is a perspective schematic view showing the configuration of a cutting insert according to a first embodiment. FIG. 2 is a plan schematic view showing the configuration of a cutting insert according to the first embodiment. FIG. 3 is an enlarged schematic view of region III in FIG. 2. FIG. 4 is a cross-sectional schematic view taken along line IV-IV in FIG. 2. FIG. 5 is a cross-sectional schematic view taken along line V-V in FIG. 2. FIG. 6 is a cross-sectional schematic view taken along line VI-VI in FIG. 2. FIG. 7 is a side schematic view illustrating the configuration of a milling cutting tool according to the present embodiment. FIG. 8 is a side schematic view illustrating the configuration of a turning cutting tool according to the present embodiment. FIG. 9 is a plan schematic view showing the configuration of a first modified example of the cutting insert according to the first embodiment. FIG. 10 is a plan schematic view showing the configuration of a second modified example of the cutting insert according to the first embodiment. FIG. 11 is a side schematic view showing a state in which a workpiece is cut using the milling cutting tool. FIG. 12 is a plan schematic view showing the configuration of a cutting insert according to a second embodiment. FIG. 13 is a schematic view illustrating the direction in which the joint extends. Fig. 14 is a plan view schematic diagram showing the configuration of a cutting insert according to a third embodiment. Fig. 15 is a cross-sectional view schematic diagram taken along line XV-XV in Fig. 14. Fig. 16 is a cross-sectional view schematic diagram taken along line XVI-XVI in Fig. 14. Fig. 17 is a plan view schematic diagram showing the configuration of a cutting insert according to a fourth embodiment.

[0006] [Description of an embodiment of the present disclosure] First, an embodiment of the present disclosure (also referred to as the present embodiment) will be described.

[0007] (1) A milling cutting tool according to the present disclosure includes a cutting insert and a body. The cutting insert is attached to the body. The body is rotatable around a rotation axis. The cutting insert includes a base member and a cutting member joined to the base member. The cutting member has a major cutting edge portion. The cutting insert has a mounting surface attached to the body and an upper surface opposite the mounting surface. When viewed in a direction perpendicular to the upper surface, an angle formed between a reference line perpendicular to the rotation axis and a joint between the base member and the cutting member is 5° or more and 20° or less. When viewed in a direction perpendicular to the upper surface, an angle formed between the reference line and the major cutting edge portion is 5° or more and 20° or less.

[0008] (2) In the milling cutting tool according to (1) above, the cutting member may be made of cubic boron nitride.

[0009] (3) In the milling cutting tool according to (1) or (2) above, the joint may be linear when viewed in a direction perpendicular to the top surface.

[0010] (4) In the milling cutting tool according to (1) or (2) above, the joint may be curved when viewed in a direction perpendicular to the top surface.

[0011] (5) A turning cutting tool according to the present disclosure includes a cutting insert and a holder. The cutting insert is attached to the holder. The holder includes a shank extending along a central axis. The cutting insert includes a base member and a cutting member joined to the base member. The cutting member has a major cutting edge portion. The cutting insert has a mounting surface attached to the holder and an upper surface opposite the mounting surface. When viewed in a direction perpendicular to the upper surface, an angle formed between a reference line perpendicular to the central axis and a joint between the base member and the cutting member is 5° or more and 20° or less. When viewed in a direction perpendicular to the upper surface, an angle formed between the reference line and the major cutting edge portion is 5° or more and 20° or less.

[0012] (6) In the turning cutting tool according to (5) above, the cutting member may be made of cubic boron nitride.

[0013] (7) In the turning cutting tool according to (5) or (6) above, the joint may be linear when viewed in a direction perpendicular to the top surface.

[0014] (8) In the turning cutting tool according to (5) or (6), the joint may be curved when viewed in a direction perpendicular to the top surface. [Details of the embodiment of the present disclosure] Specific examples of the embodiment of the present disclosure will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and descriptions thereof will not be repeated.

[0015] First Embodiment Fig. 1 is a schematic perspective view showing the configuration of a cutting insert according to a first embodiment. Fig. 2 is a schematic plan view showing the configuration of the cutting insert according to the first embodiment.

[0016] 1 and 2 , the cutting insert 1 according to the first embodiment has a base member 30 and a cutting member 7. The base member 30 is made of, for example, a cemented carbide alloy. The cutting member 7 is made of, for example, cubic boron nitride. The cutting member 7 is bonded to the base member 30. A bonded portion 4 between the cutting member 7 and the base member 30 is formed of, for example, a brazing material such as silver brazing.

[0017] The cutting member 7 has a rake face 40, a flank 50, and a cutting edge 60. The flank 50 is continuous with the rake face 40. The ridge between the rake face 40 and the flank 50 forms the cutting edge 60. The cutting edge 60 has a major cutting edge portion 61, a minor cutting edge portion 62, and a corner cutting edge portion 63. The major cutting edge portion 61 is continuous with each of the minor cutting edge portion 62 and the corner cutting edge portion 63. The major cutting edge portion 61 is located between the minor cutting edge portion 62 and the corner cutting edge portion 63.

[0018] The rake face 40 has a first rake face portion 41, a second rake face portion 42, and a third rake face portion 43. The flank face 50 has a first flank face portion 51, a second flank face portion 52, and a third flank face portion 53. The ridge line between the first rake face portion 41 and the first flank face portion 51 forms a major cutting edge portion 61. The ridge line between the second rake face portion 42 and the second flank face portion 52 forms a minor cutting edge portion 62. The ridge line between the third rake face portion 43 and the third flank face portion 53 forms a corner cutting edge portion 63.

[0019] As shown in Fig. 2, the first rake face portion 41 has a first region 41a and a second region 41b. The first region 41a is continuous with the second region 41b. The second rake face portion 42 has a third region 42a and a fourth region 42b. The third region 42a is continuous with the fourth region 42b. The third rake face portion 43 has a fifth region 43a and a sixth region 43b. The fifth region 43a is continuous with the sixth region 43b.

[0020] 1 and 2, the base member 30 has an upper surface 35, a mounting surface 36, and an outer peripheral surface 37. The mounting surface 36 is a surface that is attached to a body 90 (see FIG. 7) or a holder 70 (see FIG. 8), which will be described later. The mounting surface 36 is located opposite the upper surface 35. A through hole 2 is formed in the base member 30. The through hole 2 opens to both the upper surface 35 and the mounting surface 36. The outer peripheral surface 37 is continuous with both the upper surface 35 and the mounting surface 36.

[0021] As shown in Fig. 1 , a notch 3 is provided in the base member 30. The notch 3 is provided in a part of the boundary between the outer peripheral surface 37 and the upper surface 35. The cutting member 7 is disposed in the notch 3. The cutting member 7 is joined to the base member 30 at the notch 3.

[0022] The outer peripheral surface 37 has a first outer peripheral region 31, a second outer peripheral region 32, a third outer peripheral region 33, and a fourth outer peripheral region 34. The first outer peripheral region 31 is disposed between the first clearance surface 51 and the mounting surface 36. The second outer peripheral region 32 is disposed between the second clearance surface 52 and the mounting surface 36. The third outer peripheral region 33 is disposed between the third clearance surface 53 and the mounting surface 36. The fourth outer peripheral region 34 is continuous with both the upper surface 35 and the mounting surface 36. The first outer peripheral region 31 is disposed between the second outer peripheral region 32 and the third outer peripheral region 33.

[0023] Fig. 3 is an enlarged schematic view of region III in Fig. 2. In Fig. 3, the outer peripheral surface 37 of the base member 30 is omitted.

[0024] As shown in FIG. 3 , the major cutting edge portion 61 is linear when viewed in a direction perpendicular to the upper surface 35. Similarly, the minor cutting edge portion 62 is linear when viewed in a direction perpendicular to the upper surface 35. When viewed in a direction perpendicular to the upper surface 35, the angle between the reference line E and the major cutting edge portion 61 is defined as a first angle θ1. The first angle θ1 is measured at the intersection (first intersection P1) between the tangent to the major cutting edge portion 61 and the tangent to the minor cutting edge portion 62. In measuring the first angle θ1, the reference line E is set to pass through the first intersection P1. The first angle θ1 is equal to or greater than 5° and equal to or less than 20°. The first angle θ1 may be equal to or greater than 7°, or may be equal to or greater than 9°. The first angle θ1 may be equal to or less than 18°, or may be equal to or less than 16°.

[0025] The reference line E is a line parallel to the feed direction C of the cutting tool. Specifically, in the case of the turning cutting tool 101, the reference line E is a line perpendicular to the rotation axis B of the body 90 when viewed in a direction perpendicular to the top surface 35 (see FIG. 7). In the case of the turning cutting tool 102, the reference line E is a line perpendicular to the central axis D of the shank 71 when viewed in a direction perpendicular to the top surface 35 (see FIG. 8).

[0026] 3 , the joint 4 between the base member 30 and the cutting member 7 is linear when viewed in a direction perpendicular to the upper surface 35. The angle between the reference line E and the joint 4 is defined as a second angle θ2. The second angle θ2 is measured at the intersection (second intersection P2) of a tangent to the corner cutting edge portion 63 at the end of the corner cutting edge portion 63 opposite the main cutting edge portion 61 and a tangent to the joint 4. In the case of the milling cutting tool 101, when measuring the second angle θ2, the reference line E is set by translating the reference line E set in measuring the first angle θ1 along the rotation axis B so that the reference line E and the second intersection P2 overlap when viewed in a direction perpendicular to the upper surface 35. Similarly, in the case of the turning cutting tool 102, in measuring the second angle θ2, the reference line E set in measuring the first angle θ1 is translated along the central axis D, and the reference line E is set so that the reference line E and the second intersection point P2 overlap when viewed in a direction perpendicular to the upper surface 35. The second angle θ2 is equal to or greater than 5° and equal to or less than 20°. The second angle θ2 may be equal to or greater than 7°, or may be equal to or greater than 9°. The second angle θ2 may be equal to or less than 18°, or may be equal to or less than 16°.

[0027] 3, when viewed in a direction perpendicular to the upper surface 35, the minor cutting edge portion 62 may be parallel to the reference line E. In this embodiment, the first angle θ1 is the same as the second angle θ2. When viewed in a direction perpendicular to the upper surface 35, the corner cutting edge portion 63 may be curved.

[0028] Fig. 4 is a schematic cross-sectional view taken along line IV-IV in Fig. 2. The cross section shown in Fig. 4 is perpendicular to the main cutting edge portion 61 and also perpendicular to the upper surface 35.

[0029] 4 , the upper surface 35 is parallel to the mounting surface 36. The second region 41b of the first scooping surface portion 41 extends along the upper surface 35. The first region 41a of the first scooping surface portion 41 is inclined with respect to both the second region 41b and the first flank surface portion 51. The first flank surface portion 51 is disposed along the first outer peripheral region 31. The first outer peripheral region 31 is continuous with the mounting surface 36.

[0030] In the cross section shown in FIG. 4 , the angle formed between the upper surface 35 and the first outer peripheral region 31 is a third angle θ3. The third angle θ3 is greater than 90°. The angle formed between the first region 41a of the first rake face portion 41 and the first flank face portion 51 is greater than 90°. From another perspective, the clearance angle of the first flank face portion 51 may be negative. In the cross section shown in FIG. 4 , the angle formed between the mounting surface 36 and the first outer peripheral region 31 is a fourth angle θ4. The fourth angle θ4 is less than 90°.

[0031] Fig. 5 is a schematic cross-sectional view taken along line VV in Fig. 2. The cross section shown in Fig. 5 is perpendicular to the minor cutting edge portion 62 and also perpendicular to the upper surface 35.

[0032] 5 , the fourth region 42b of the second rake face portion 42 extends along the upper surface 35. The third region 42a of the second rake face portion 42 is inclined with respect to both the fourth region 42b and the second flank face portion 52. The second flank face portion 52 is disposed along the second outer peripheral region 32. The second outer peripheral region 32 is continuous with the mounting surface 36.

[0033] In the cross section shown in FIG. 5 , the angle formed between the upper surface 35 and the second outer peripheral region 32 is a fifth angle θ5. The fifth angle θ5 may be smaller than the third angle θ3. The fifth angle θ5 is, for example, 90°. The angle formed between the third region 42a of the second rake face portion 42 and the second flank face portion 52 may be, for example, 90°. From another perspective, the clearance angle of the second flank face portion 52 may be 0°. In the cross section shown in FIG. 5 , the angle formed between the mounting surface 36 and the second outer peripheral region 32 is a sixth angle θ6. The sixth angle θ6 may be larger than the fourth angle θ4. The sixth angle θ6 is, for example, 90°.

[0034] Fig. 6 is a schematic cross-sectional view taken along line VI-VI in Fig. 2. The cross section shown in Fig. 6 is parallel to the minor cutting edge portion 62, intersects with the fourth outer peripheral region 34, and is perpendicular to the upper surface 35.

[0035] 6 , the fourth outer peripheral region 34 has a fifth outer peripheral region 5 and a sixth outer peripheral region 6. The sixth outer peripheral region 6 is opposite the fifth outer peripheral region 5. The through-hole 2 is located between the fifth outer peripheral region 5 and the sixth outer peripheral region 6. The fifth outer peripheral region 5 is continuous with both the upper surface 35 and the mounting surface 36. Similarly, the sixth outer peripheral region 6 is continuous with both the upper surface 35 and the mounting surface 36.

[0036] In the cross section shown in FIG. 6 , the fifth outer peripheral region 5 is inclined with respect to each of the upper surface 35 and the mounting surface 36. The angle formed between the upper surface 35 and the fifth outer peripheral region 5 is a seventh angle θ7. The seventh angle θ7 is smaller than 90°. In the cross section shown in FIG. 6 , the angle formed between the mounting surface 36 and the fifth outer peripheral region 5 is an eighth angle θ8. The eighth angle θ8 is larger than the seventh angle θ7. The eighth angle θ8 is larger than 90°.

[0037] In the cross section shown in FIG. 6 , the sixth outer peripheral region 6 is inclined with respect to each of the upper surface 35 and the mounting surface 36. The angle formed between the upper surface 35 and the sixth outer peripheral region 6 is a ninth angle θ9. The ninth angle θ9 is greater than 90°. In the cross section shown in FIG. 6 , the angle formed between the mounting surface 36 and the sixth outer peripheral region 6 is a tenth angle θ10. The tenth angle θ10 is smaller than the ninth angle θ9. The tenth angle θ10 is smaller than 90°.

[0038] Next, the configuration of the milling cutting tool 101 according to this embodiment will be described. FIG. 7 is a side view schematically illustrating the configuration of the milling cutting tool 101 according to this embodiment. As shown in FIG. 7 , the milling cutting tool 101 has a body 90, a cutting insert 1, and a fastening screw 93. The body 90 is rotatable around a rotation axis B. The body 90 is attached to a machine tool (not shown) via an arbor (not shown). An insert mounting groove 92 is provided on an outer periphery 91 of the body 90. The cutting insert 1 is disposed in the insert mounting groove 92. The cutting insert 1 is attached to the body 90 using the fastening screw 93. The fastening screw 93 is inserted into the through hole 2 of the cutting insert 1. The milling cutting tool 101 is, for example, a milling tool.

[0039] 7, the milling cutting tool 101 is disposed opposite to the workpiece 80. The milling cutting tool 101 is movable along a feed direction C while rotating around a rotation axis B. The milling cutting tool 101 may have the cutting insert 1 according to the first embodiment, or may have the cutting insert 1 according to another embodiment described later.

[0040] Fig. 8 is a schematic side view illustrating the configuration of a turning cutting tool 102 according to this embodiment. As shown in Fig. 8, the turning cutting tool 102 according to this embodiment has a holder 70, a cutting insert 1, and a fastening screw 93. The cutting insert 1 is attached to the holder 70. The holder 70 has a shank 71 and an insert holding member 72.

[0041] The shank 71 is attached to a machine tool (not shown). The shank 71 extends along a central axis D. The insert holding member 72 is connected to the shank 71. The insert holding member 72 is provided with an insert mounting groove 73. The insert mounting groove 73 is provided at a position spaced apart from the central axis D in the feed direction C. The cutting insert 1 is disposed in the insert mounting groove 73. The cutting insert 1 is attached to the insert holding member 72 using a fastening screw 93. The fastening screw 93 is inserted into the through hole 2 of the cutting insert 1.

[0042] The workpiece 80 rotates around the axis F. As shown in Fig. 8 , the turning cutting tool 102 is disposed so that the central axis D of the shank 71 is perpendicular to the axis F. The turning cutting tool 102 is movable along the feed direction C. The turning cutting tool 102 may have the cutting insert 1 according to the first embodiment, or may have the cutting insert 1 according to other embodiments described later.

[0043] 9 is a schematic plan view showing the configuration of a first modified example of the cutting insert 1 according to the first embodiment. The region shown in FIG. 9 corresponds to the region shown in FIG.

[0044] As shown in FIG. 9 , when viewed in a direction perpendicular to the upper surface 35, the angle between the reference line E and the main cutting edge portion 61 is defined as a first angle θ1. The first angle θ1 is equal to or greater than 5° and equal to or less than 20°. When viewed in a direction perpendicular to the upper surface 35, the angle between the reference line E and the joint portion 4 is defined as a second angle θ2. The second angle θ2 may be greater than the first angle θ1. In this case, the corner cutting edge portion 63 can be extended upward. Therefore, the cutting insert of the first modified example is suitable for corner cutting.

[0045] The value obtained by subtracting the first angle θ1 from the second angle θ2 may be equal to or greater than 1°, or may be equal to or greater than 2°. The value obtained by subtracting the first angle θ1 from the second angle θ2 may be equal to or less than 5°, or may be equal to or less than 4°.

[0046] 10 is a schematic plan view showing the configuration of a second modified example of the cutting insert 1 according to the first embodiment. The region shown in FIG. 10 corresponds to the region shown in FIG.

[0047] As shown in Fig. 10, the second angle θ2 may be smaller than the first angle θ1. In this case, the volume of the relatively expensive cutting member 7 can be reduced. The first angle θ1 is equal to or greater than 5° and equal to or less than 20°. The value obtained by subtracting the second angle θ2 from the first angle θ1 may be equal to or greater than 1°, or may be equal to or greater than 2°. The value obtained by subtracting the second angle θ2 from the first angle θ1 may be equal to or less than 5°, or may be equal to or less than 4°.

[0048] Next, a method for cutting a workpiece 80 using the milling cutting tool 101 will be described. Fig. 11 is a side schematic view showing a state in which the workpiece 80 is cut using the milling cutting tool 101. The workpiece 80 is, for example, high-hardness steel. The Rockwell hardness of the workpiece 80 is, for example, 50 HRC or more and 70 HRC or less.

[0049] As shown in Figures 7 and 11, the milling cutting tool 101 moves along the feed direction C while rotating around the rotation axis B. The distance from the minor cutting edge 60 to the surface of the workpiece 80 in the direction along the rotation axis B corresponds to the axial depth of cut H. The milling cutting tool 101 moves along the feed direction C while rotating around the rotation axis B. As a result, the major cutting edge portion 61 and the minor cutting edge portion 62 of the cutting insert 1 cut the workpiece 80. The major cutting edge portion 61 is a blade that is mainly responsible for cutting the workpiece 80. The minor cutting edge portion 62 is, for example, a wiper edge that performs finish machining. Note that the workpiece 80 may be cut using the corner cutting edge portion 63 in addition to the major cutting edge portion 61 and the minor cutting edge portion 62.

[0050] Although the base member 30 has been described above as being made of cemented carbide, the material of the base member 30 is not limited to cemented carbide. The base member 30 may be made of high-speed tool steel, ceramic, or the like. Similarly, the material of the cutting member 7 is not limited to cubic boron nitride. The cutting member 7 may be made of polycrystalline diamond, single crystal diamond, or the like.

[0051] Second Embodiment Next, the configuration of the cutting insert 1 according to the second embodiment will be described. The cutting insert 1 according to the second embodiment differs from the cutting insert 1 according to the first embodiment mainly in that the shape of the joint portion 4 is curved, but other configurations are substantially the same as those of the cutting insert 1 according to the first embodiment. The following description will focus on the configurations that differ from the cutting insert 1 according to the first embodiment.

[0052] Fig. 12 is a schematic plan view showing the configuration of the cutting insert 1 according to the second embodiment. As shown in Fig. 12, the joint 4 may have a curved shape when viewed in a direction perpendicular to the upper surface 35. Specifically, the joint 4 has a wave shape.

[0053] 13 is a schematic diagram illustrating the extension direction of the joint 4. When viewed in a direction perpendicular to the upper surface 35, the X axis is parallel to the extension direction of the minor cutting edge portion 62, and the Y axis is perpendicular to the extension direction of the minor cutting edge portion 62.

[0054] As shown in FIG. 13 , when viewed in a direction perpendicular to the top surface 35, the joint 4 has a first end A1 and a second end A2. The second end A2 is located opposite the first end A1. The joint 4 is approximated by a regression line G. The regression line G is determined using the least squares method. Specifically, the regression line G is determined so that the sum of the squares of the distances between the position of the joint 4 in the Y direction and the regression line G is minimized. In a direction parallel to the X direction, the distance between the second end A2 and the first end A1 is divided into 100 parts. The regression line G is determined using data for the 101 divided parts. When the joint 4 is curved when viewed in a direction perpendicular to the top surface 35, the angle between the joint 4 and the reference line E (second angle θ2) is the angle between the regression line G and the reference line E.

[0055] (Third embodiment) Next, the configuration of the cutting insert 1 according to the third embodiment will be described. The cutting insert 1 according to the third embodiment differs from the cutting insert 1 according to the first embodiment mainly in that the clearance angle of the first clearance surface portion 51 is positive, but other configurations are substantially the same as those of the cutting insert 1 according to the first embodiment. The following description will focus on the configurations that differ from the cutting insert 1 according to the first embodiment.

[0056] Fig. 14 is a schematic plan view showing the configuration of the cutting insert 1 according to the third embodiment. As shown in Fig. 14, the cutting edge 60 of the cutting insert 1 according to the third embodiment has a major cutting edge portion 61, a minor cutting edge portion 62, and a corner cutting edge portion 63. The major cutting edge portion 61 is continuous with each of the minor cutting edge portion 62 and the corner cutting edge portion 63. The major cutting edge portion 61 is located between the minor cutting edge portion 62 and the corner cutting edge portion 63.

[0057] Fig. 15 is a schematic cross-sectional view taken along line XV-XV in Fig. 14. The cross section shown in Fig. 15 is perpendicular to the main cutting edge portion 61 and also perpendicular to the upper surface 35.

[0058] 15 , the upper surface 35 is parallel to the mounting surface 36. The second region 41b of the first scooping surface portion 41 extends along the upper surface 35. The first region 41a of the first scooping surface portion 41 is inclined with respect to both the second region 41b and the first flank surface portion 51. The first flank surface portion 51 is disposed along the first outer peripheral region 31. The first outer peripheral region 31 is continuous with the mounting surface 36.

[0059] In the cross section shown in FIG. 15 , the angle formed between the upper surface 35 and the first outer peripheral region 31 is a third angle θ3. The third angle θ3 is smaller than 90°. The angle formed between the first region 41a of the first rake face portion 41 and the first flank face portion 51 is smaller than 90°. From another perspective, the clearance angle of the first flank face portion 51 is positive. In the cross section shown in FIG. 15 , the angle formed between the mounting surface 36 and the first outer peripheral region 31 is a fourth angle θ4. The fourth angle θ4 is larger than 90°.

[0060] Fig. 16 is a schematic cross-sectional view taken along line XVI-XVI in Fig. 14. The cross section shown in Fig. 16 is perpendicular to the minor cutting edge portion 62 and also perpendicular to the upper surface 35.

[0061] 16 , the fourth region 42b of the second rake face portion 42 extends along the upper surface 35. The third region 42a of the second rake face portion 42 is inclined with respect to both the fourth region 42b and the second flank face portion 52. The second flank face portion 52 is disposed along the second outer peripheral region 32. The second outer peripheral region 32 is continuous with the mounting surface 36.

[0062] In the cross section shown in FIG. 16 , the angle formed between the upper surface 35 and the second outer peripheral region 32 is a fifth angle θ5. The fifth angle θ5 is smaller than 90°. The angle formed between the third region 42a of the second rake face portion 42 and the second flank face portion 52 is smaller than 90°. From another perspective, the clearance angle of the second flank face portion 52 may be positive. In the cross section shown in FIG. 16 , the angle formed between the mounting surface 36 and the second outer peripheral region 32 is a sixth angle θ6. The sixth angle θ6 is larger than 90°.

[0063] (Fourth embodiment) Next, the configuration of the cutting insert 1 according to the fourth embodiment will be described. The cutting insert 1 according to the fourth embodiment differs from the cutting insert 1 according to the first embodiment mainly in that it has three cutting members 7, but other configurations are substantially the same as those of the cutting insert 1 according to the first embodiment. The following description will focus on the configurations that differ from the cutting insert 1 according to the first embodiment.

[0064] Fig. 17 is a schematic plan view showing the configuration of a cutting insert 1 according to a fourth embodiment. As shown in Fig. 17, the cutting insert 1 according to the fourth embodiment has one base member 30 and three cutting members 7. Each of the three cutting members 7 is joined to the base member 30. Each of the three cutting members 7 is made of, for example, cubic boron nitride. Joint portions 4 between each of the three cutting members 7 and the base member 30 are made of, for example, a brazing material such as silver brazing.

[0065] Each of the three cutting members 7 has a cutting edge 60. The cutting edge 60 has a major cutting edge portion 61, a minor cutting edge portion 62, and a corner cutting edge portion 63. The major cutting edge portion 61 is continuous with each of the minor cutting edge portion 62 and the corner cutting edge portion 63. The major cutting edge portion 61 is located between the minor cutting edge portion 62 and the corner cutting edge portion 63. As shown in FIG. 17 , the shape of the cutting insert 1 according to the fourth embodiment may be three-fold symmetric with respect to the extension direction of the through hole 2. In other words, the shape of the cutting insert 1 after rotating 120° around the axis of the extension direction of the through hole 2 is the same as the shape of the cutting insert 1 before rotation.

[0066] Next, the effects of the milling cutting tool 101 and the turning cutting tool 102 according to this embodiment will be described.

[0067] According to the milling cutting tool 101 of this embodiment, when viewed in a direction perpendicular to the upper surface 35, the angle between the reference line E perpendicular to the rotation axis B and the joint 4 between the base member 30 and the cutting member 7 is 5° or more and 20° or less. This increases the length of the joint 4, which is formed using, for example, a brazing material. This therefore allows the cutting member 7 to be firmly joined to the base member 30. This reduces the possibility of the cutting member 7 falling off the base member 30 during high-efficiency milling with a large feed rate per cutting edge 60.

[0068] When viewed in a direction perpendicular to the upper surface 35, the angle between the reference line E and the major cutting edge portion 61 is 5° or more and 20° or less. This increases the length of contact of the major cutting edge 60 with the workpiece 80 compared to when the angle between the reference line E and the major cutting edge portion 61 is greater than 20°. This reduces the load per unit length on the major cutting edge 60. As a result, the feed rate per cutting edge 60 can be increased. This allows for highly efficient milling of high-hardness steel.

[0069] According to the milling cutting tool 101 of this embodiment, the joint 4 may be curved when viewed in a direction perpendicular to the upper surface 35. This allows the length of the joint 4 to be longer than when the joint 4 is linear. Therefore, the cutting member 7 can be firmly joined to the base member 30.

[0070] According to the turning cutting tool 102 of this embodiment, when viewed in a direction perpendicular to the top surface 35, the angle between the reference line E perpendicular to the central axis D of the shank 71 and the joint 4 between the base member 30 and the cutting member 7 is 5° or more and 20° or less. This increases the length of the joint 4, which is formed using, for example, brazing material. This allows the cutting member 7 to be firmly joined to the base member 30. This reduces the possibility of the cutting member 7 falling off the base member 30 during high-efficiency turning with a large feed rate per cutting edge 60.

[0071] When viewed in a direction perpendicular to the upper surface 35, the angle between the reference line E and the major cutting edge portion 61 is 5° or more and 20° or less. This increases the length of contact of the major cutting edge 60 with the workpiece 80 compared to when the angle between the reference line E and the major cutting edge portion 61 is greater than 20°. This reduces the load per unit length on the major cutting edge 60. As a result, the feed rate per cutting edge 60 can be increased. This allows for highly efficient turning of high-hardness steel.

[0072] According to the turning cutting tool 102 of this embodiment, the joint 4 may be curved when viewed in a direction perpendicular to the upper surface 35. This allows the length of the joint 4 to be longer than when the joint 4 is linear. Therefore, the cutting member 7 can be firmly joined to the base member 30.

[0073] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0074] 1 Cutting insert, 2 Through hole, 3 Notch, 4 Joint portion, 5 Fifth outer peripheral region, 6 Sixth outer peripheral region, 7 Cutting member, 30 Base member, 31 First outer peripheral region, 32 Second outer peripheral region, 33 Third outer peripheral region, 34 Fourth outer peripheral region, 35 Upper surface, 36 Mounting surface, 37 Outer peripheral surface, 40 Rake face, 41 First rake face portion, 41a First region, 41b Second region, 42 Second rake face portion, 42a Third region, 42b Fourth region, 43 Third rake face portion, 43a Fifth region, 43b Sixth region, 50 Rake face, 51 First rake face portion, 52 Second rake face portion, 53 Third rake face portion, 60 Cutting edge, 61 Major cutting edge portion, 62 Minor cutting edge portion, 63 Corner cutting edge portion, 70 Holder, 71 Shank, 72 Insert holding member, 73, 92 Insert mounting groove, 80 Workpiece material, 90 Body, 91 Outer periphery, 93 Fastening screw, 101 Turning cutting tool, 102 Turning cutting tool, A1 First end, A2 Second end, B Rotation axis, C Feed direction, D Central axis, E Reference line, F Axis line, G Regression line, H Axial cutting amount, P1 First intersection, P2 Second intersection.

Claims

1. A milling cutting tool comprising: a cutting insert; and a body to which the cutting insert is attached and which is rotatable around a rotation axis, wherein the cutting insert includes a base member and a cutting member joined to the base member, wherein the cutting member has a major cutting edge portion, wherein the cutting insert has a mounting surface attached to the body and an upper surface opposite to the mounting surface, wherein, when viewed in a direction perpendicular to the upper surface, an angle formed by a reference line perpendicular to the rotation axis and a joint between the base member and the cutting member is between 5° and 20°, and when viewed in a direction perpendicular to the upper surface, an angle formed by the reference line and the major cutting edge portion is between 5° and 20°.

2. The milling cutting tool according to claim 1, wherein the cutting member is made of cubic boron nitride.

3. A milling cutting tool according to claim 1 or 2, wherein the joint is linear when viewed in a direction perpendicular to the upper surface.

4. A milling cutting tool according to claim 1 or 2, wherein the joint is curved when viewed in a direction perpendicular to the upper surface.

5. A turning cutting tool comprising: a cutting insert; and a holder to which the cutting insert is attached, wherein the holder includes a shank extending along a central axis, the cutting insert includes a base member and a cutting member joined to the base member, the cutting member having a major cutting edge portion, the cutting insert having a mounting surface attached to the holder and an upper surface opposite to the mounting surface, wherein, when viewed in a direction perpendicular to the upper surface, an angle formed by a reference line perpendicular to the central axis and a joint between the base member and the cutting member is between 5° and 20°, and when viewed in a direction perpendicular to the upper surface, an angle formed by the reference line and the major cutting edge portion is between 5° and 20°.

6. The turning cutting tool according to claim 5, wherein said cutting member is made of cubic boron nitride.

7. A turning cutting tool according to claim 5 or 6, wherein the joint is linear when viewed in a direction perpendicular to the upper surface.

8. A turning cutting tool according to claim 5 or 6, wherein the joint is curved when viewed in a direction perpendicular to the upper surface.

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