Cutting Insert for Rotary Cutting Tool and Rotary Cutting Tool

Abstract

The cutting blade for a rotary cutting tool has a first surface, a second surface, and an outer peripheral surface. The second surface faces the first surface. The outer peripheral surface is connected to each of the first surface and the second surface. The ridge line between the first surface and the outer peripheral surface includes a first cutting edge. The ridge line between the second surface and the outer peripheral surface includes a second cutting edge. The first surface includes a planar first seating surface. The second surface includes a planar second seating surface. The first cutting edge has a first major cutting edge portion and a first minor cutting edge portion. The second cutting edge has a second major cutting edge portion and a second minor cutting edge portion. When viewed in the direction from the first surface toward the second surface, at least a part of the second minor cutting edge portion is located outside the first major cutting edge portion, and at least a part of the first minor cutting edge portion is located outside the second major cutting edge portion. When viewed in the direction from the first surface toward the second surface, each of the first minor cutting edge portion and the second minor cutting edge portion is curved. The outer peripheral surface includes a planar third seating surface.

Description

Technical Field

[0001] The present invention relates to a cutting blade for a rotary cutting tool and a rotary cutting tool. Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2017-124464 (Patent Document 1) discloses a cutting blade having a main cutting edge and a sub-cutting edge. When viewed from above, the shapes of the main cutting edge and the sub-cutting edge are each linear.

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-124464 Summary of the Invention

[0004] The cutting blade for a rotary cutting tool according to the present invention has a first surface, a second surface, and an outer peripheral surface. The second surface faces the first surface. The outer peripheral surface is connected to each of the first surface and the second surface. The ridge line between the first surface and the outer peripheral surface includes a first cutting edge. The ridge line between the second surface and the outer peripheral surface includes a second cutting edge. The first surface includes a planar first seating surface. The second surface includes a planar second seating surface. The first cutting edge has a first main cutting edge portion and a first sub-cutting edge portion. The second cutting edge has a second main cutting edge portion and a second sub-cutting edge portion. When viewed in the direction from the first surface toward the second surface, at least a part of the second sub-cutting edge portion is located outside the first main cutting edge portion, and at least a part of the first sub-cutting edge portion is located outside the second main cutting edge portion. When viewed in the direction from the first surface toward the second surface, each of the first sub-cutting edge portion and the second sub-cutting edge portion is curved. The outer peripheral surface includes a planar third seating surface.

[0005] The cutting blade for a rotary cutting tool according to the present invention has a first surface, a second surface, and an outer peripheral surface. The second surface faces the first surface. The outer peripheral surface is connected to each of the first surface and the second surface. The ridge line between the first surface and the outer peripheral surface includes a first cutting edge. The ridge line between the second surface and the outer peripheral surface includes a second cutting edge. The first surface includes a planar first seating surface. The second surface includes a planar second seating surface. The first cutting edge has a first main cutting edge portion and a first sub-cutting edge portion. The second cutting edge has a second main cutting edge portion and a second sub-cutting edge portion. When viewed in the direction from the first surface toward the second surface, at least a part of the second sub-cutting edge portion is located outside the first main cutting edge portion, and at least a part of the first sub-cutting edge portion is located outside the second main cutting edge portion. When viewed in the direction from the first surface toward the second surface, each of the first sub-cutting edge portion and the second sub-cutting edge portion is curved. The outer peripheral surface includes a planar third seating surface. In a cross-section parallel to the direction from the first surface toward the second surface and intersecting the first main cutting edge portion, the third seating surface, and the second sub-cutting edge portion, the angle formed by the third seating surface and the first seating surface is an obtuse angle, and the angle formed by the third seating surface and the second seating surface is an acute angle. When viewed in the direction from the first surface toward the second surface, the ridge line between the first surface and the outer peripheral surface has a shape rotationally symmetric about the central axis by 120°.

[0006] The cutting blade for a rotary cutting tool according to the present invention has a first surface, a second surface, and an outer peripheral surface. The second surface faces the first surface. The outer peripheral surface is connected to each of the first surface and the second surface. The ridge line between the first surface and the outer peripheral surface includes a first cutting edge. The ridge line between the second surface and the outer peripheral surface includes a second cutting edge. The first surface includes a planar first seating surface. The second surface includes a planar second seating surface. The first cutting edge has a first major cutting edge portion and a first minor cutting edge portion. The second cutting edge has a second major cutting edge portion and a second minor cutting edge portion. When viewed in the direction from the first surface toward the second surface, at least a part of the second minor cutting edge portion is located outside the first major cutting edge portion, and at least a part of the first minor cutting edge portion is located outside the second major cutting edge portion. When viewed in the direction from the first surface toward the second surface, each of the first minor cutting edge portion and the second minor cutting edge portion is curved. The outer peripheral surface includes a planar third seating surface. In a cross-section parallel to the direction from the first surface toward the second surface and intersecting the first major cutting edge portion, the third seating surface, and the second minor cutting edge portion, the angle formed by the third seating surface and the first seating surface is an obtuse angle, and the angle formed by the third seating surface and the second seating surface is an acute angle. When viewed in the direction from the first surface toward the second surface, the ridge line between the first surface and the outer peripheral surface has a shape rotationally symmetric about the central axis by 180°. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a perspective view showing the structure of the cutting blade for a rotary cutting tool according to the first embodiment.

[0008] Figure 2 is a top view showing the structure of the cutting blade for a rotary cutting tool according to the first embodiment.

[0009] Figure 3 is a rear view showing the structure of the cutting blade for a rotary cutting tool according to the first embodiment.

[0010] Figure 4 is a side view showing the structure of the cutting blade for a rotary cutting tool according to the first embodiment.

[0011] Figure 5 is along Figure 2 a schematic cross-sectional view taken along line V-V.

[0012] Figure 6 is along Figure 2 a schematic cross-sectional view taken along line VI-VI.

[0013] Figure 7 is Figure 2 an enlarged view of region VII.

[0014] Figure 8 is Figure 3 an enlarged view of region VIII.

[0015] Figure 9 It is an oblique view showing the structure of the rotary cutting tool according to the second embodiment.

[0016] Figure 10 It is an oblique view showing the structure of the cutting insert for the rotary cutting tool according to the third embodiment.

[0017] Figure 11 It is a plan view showing the structure of the cutting insert for the rotary cutting tool according to the third embodiment.

[0018] Figure 12 It is a rear view showing the structure of the cutting insert for the rotary cutting tool according to the third embodiment.

[0019] Figure 13 It is a side view showing the structure of the cutting insert for the rotary cutting tool according to the third embodiment.

[0020] Figure 14 It is along Figure 11 A sectional view taken along line XIV-XIV.

[0021] Figure 15 It is along Figure 11 A sectional view taken along line XV-XV.

[0022] Figure 16 It is Figure 11 An enlarged view of region XVI.

[0023] Figure 17 It is Figure 12 An enlarged view of region XVII.

[0024] Figure 18 It is an oblique view showing the structure of the rotary cutting tool according to the fourth embodiment.

[0025] Figure 19 It is a sectional view showing the cutting state.

[0026] Figure 20 It is a view showing the state of obliquely machining a work material using the cutting insert for the rotary cutting tool. Detailed embodiments

[0027] [Problems to be solved by the present invention]

[0028] An object of the present invention is to provide a cutting insert for a rotary cutting tool and a rotary cutting tool capable of extending the life.

[0029] [Effects of the present invention]

[0030] According to the present invention, a cutting insert for a rotary cutting tool and a rotary cutting tool capable of extending the service life can be provided.

[0031] [Description of Embodiments of the Present Invention]

[0032] First, embodiments of the present invention will be described by way of example.

[0033] (1) The cutting insert 100 for a rotary cutting tool according to the present invention has a first surface 10, a second surface 20, and an outer peripheral surface 30. The second surface 20 is opposite to the first surface 10. The outer peripheral surface 30 is connected to the first surface 10 and the second surface 20 respectively. The ridge line of the first surface 10 and the outer peripheral surface 30 includes a first cutting edge 1. The ridge line of the second surface 20 and the outer peripheral surface 30 includes a second cutting edge 2. The first surface 10 includes a planar first seating surface 11. The second surface 20 includes a planar second seating surface 21. The first cutting edge 1 has a first main cutting edge portion 51 and a first sub-cutting edge portion 52. The second cutting edge 2 has a second main cutting edge portion 61 and a second sub-cutting edge portion 62. When viewed in the direction from the first surface 10 toward the second surface 20, at least a part of the second sub-cutting edge portion 62 is located outside the first main cutting edge portion 51, and at least a part of the first sub-cutting edge portion 52 is located outside the second main cutting edge portion 61. When viewed in the direction from the first surface 10 toward the second surface 20, the first sub-cutting edge portion 52 and the second sub-cutting edge portion 62 are each curved. The outer peripheral surface 30 includes a planar third seating surface 33.

[0034] (2) The cutting insert 100 for a rotary cutting tool according to the above (1) may be such that in a cross-section parallel to the direction from the first surface 10 toward the second surface 20 and intersecting the first main cutting edge portion 51, the third seating surface 33, and the second sub-cutting edge portion 62, the angle formed by the third seating surface 33 and the first seating surface 11 is an obtuse angle, and the angle formed by the third seating surface 33 and the second seating surface 21 is an acute angle.

[0035] (3) The cutting insert 100 for a rotary cutting tool according to the above (2) may be such that in a cross-section parallel to the direction from the first surface 10 toward the second surface 20 and intersecting the first main cutting edge portion 51, the third seating surface 33, and the second sub-cutting edge portion 62, the angle formed by the third seating surface 33 and the first seating surface 11 is 91° or more and 95° or less.

[0036] (4) The cutting insert 100 for a rotary cutting tool according to any one of the above (1) to (3) may be such that when viewed in the direction from the first surface 10 toward the second surface 20, the ridge line of the first surface 10 and the outer peripheral surface 30 has a shape rotationally symmetric about the central axis A by 120°.

[0037] (5) The cutting blade 100 for a rotary cutting tool according to (4) above may be such that the outer peripheral surface 30 includes a flank surface 36 located between the first major cutting edge portion 51 and the third seating surface 33. The flank surface 36 may be inclined with respect to the third seating surface 33.

[0038] (6) The cutting blade 100 for a rotary cutting tool according to any one of (1) to (3) above may be such that, when viewed in the direction from the first surface 10 toward the second surface 20, the ridge line between the first surface 10 and the outer peripheral surface 30 has a shape that is rotationally symmetric about the central axis A by 180°.

[0039] (7) The cutting blade 100 for a rotary cutting tool according to any one of (1) to (6) above may be such that the first major cutting edge portion 51 includes a first portion 71, a second portion 72 connected to the first portion 71, and a third portion 73 that is away from the first portion 71 and connected to the second portion 72. The second major cutting edge portion 61 may include a fourth portion 74, a fifth portion 75 connected to the fourth portion 74, and a sixth portion 76 that is away from the fourth portion 74 and connected to the fifth portion 75. Each of the first portion 71, the third portion 73, the fourth portion 74, and the sixth portion 76 may be curved.

[0040] (8) The cutting blade 100 for a rotary cutting tool according to (7) above may be such that each of the second portion 72 and the fifth portion 75 is linear.

[0041] (9) The cutting blade 100 for a rotary cutting tool according to (7) above may be such that each of the second portion 72 and the fifth portion 75 is curved.

[0042] (10) The cutting insert 100 for a rotary cutting tool according to the present invention has a first surface 10, a second surface 20, and an outer peripheral surface 30. The second surface 20 faces the first surface 10. The outer peripheral surface 30 is connected to each of the first surface 10 and the second surface 20. The ridge line between the first surface 10 and the outer peripheral surface 30 includes a first cutting edge 1. The ridge line between the second surface 20 and the outer peripheral surface 30 includes a second cutting edge 2. The first surface 10 includes a planar first seating surface 11. The second surface 20 includes a planar second seating surface 21. The first cutting edge 1 has a first main cutting edge portion 51 and a first sub-cutting edge portion 52. The second cutting edge 2 has a second main cutting edge portion 61 and a second sub-cutting edge portion 62. When observed in the direction from the first surface 10 toward the second surface 20, at least a part of the second sub-cutting edge portion 62 is located outside the first main cutting edge portion 51, and at least a part of the first sub-cutting edge portion 52 is located outside the second main cutting edge portion 61. When observed in the direction from the first surface 10 toward the second surface 20, each of the first sub-cutting edge portion 52 and the second sub-cutting edge portion 62 is curved. The outer peripheral surface 30 includes a planar third seating surface 33. In a cross-section parallel to the direction from the first surface 10 toward the second surface 20 and intersecting the first main cutting edge portion 51, the third seating surface 33, and the second sub-cutting edge portion 62, the angle formed by the third seating surface 33 and the first seating surface 11 is an obtuse angle, and the angle formed by the third seating surface 33 and the second seating surface 21 is an acute angle. When observed in the direction from the first surface 10 toward the second surface 20, the ridge line between the first surface 10 and the outer peripheral surface 30 has a shape rotationally symmetric about the central axis A by 120°.

[0043] (11) The cutting insert 100 for a rotary cutting tool according to the present invention has a first surface 10, a second surface 20, and an outer peripheral surface 30. The second surface 20 faces the first surface 10. The outer peripheral surface 30 is connected to each of the first surface 10 and the second surface 20. The ridge line between the first surface 10 and the outer peripheral surface 30 includes a first cutting edge 1. The ridge line between the second surface 20 and the outer peripheral surface 30 includes a second cutting edge 2. The first surface 10 includes a planar first seating surface 11. The second surface 20 includes a planar second seating surface 21. The first cutting edge 1 has a first major cutting edge portion 51 and a first minor cutting edge portion 52. The second cutting edge 2 has a second major cutting edge portion 61 and a second minor cutting edge portion 62. When viewed in the direction from the first surface 10 toward the second surface 20, at least a part of the second minor cutting edge portion 62 is located outside the first major cutting edge portion 51, and at least a part of the first minor cutting edge portion 52 is located outside the second major cutting edge portion 61. When viewed in the direction from the first surface 10 toward the second surface 20, each of the first minor cutting edge portion 52 and the second minor cutting edge portion 62 is curved. The outer peripheral surface 30 includes a planar third seating surface 33. In a cross-section parallel to the direction from the first surface 10 toward the second surface 20 and intersecting the first major cutting edge portion 51, the third seating surface 33, and the second minor cutting edge portion 62, the angle formed by the third seating surface 33 and the first seating surface 11 is an obtuse angle, and the angle formed by the third seating surface 33 and the second seating surface 21 is an acute angle. When viewed in the direction from the first surface 10 toward the second surface 20, the ridge line between the first surface 10 and the outer peripheral surface 30 has a shape rotationally symmetric about the central axis A by 180°.

[0044] (12) The rotary cutting tool 90 according to the present invention has the cutting insert 100 for a rotary cutting tool according to any one of the above (1) to the above (11) and a main body portion for holding the cutting insert 100 for a rotary cutting tool.

[0045] [Details of the embodiment of the present invention]

[0046] Next, the details of the embodiment of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicate descriptions are not given.

[0047] (First Embodiment)

[0048] First, the structure of the cutting insert 100 for a rotary cutting tool according to the first embodiment of the present invention will be described.

[0049] Figure 1 is a perspective view showing the structure of the cutting insert 100 for a rotary cutting tool according to the first embodiment. As Figure 1As shown, the cutting blade 100 for a rotary cutting tool according to the first embodiment mainly has a first surface 10, a second surface 20, an outer peripheral surface 30, and an inner peripheral surface 3. The second surface 20 faces the first surface 10. The outer peripheral surface 30 is connected to each of the first surface 10 and the second surface 20. Similarly, the inner peripheral surface 3 is connected to each of the first surface 10 and the second surface 20. The outer peripheral surface 30 is located outside the inner peripheral surface 3. The inner peripheral surface 3 forms a through-hole 5.

[0050] Figure 2 is a plan view showing the structure of the cutting blade 100 for a rotary cutting tool according to the first embodiment. As Figure 2 shown, the first surface 10 includes a first seating surface 11, a first bottom surface 12, a first inclined surface 13, and a first land surface 14. The first seating surface 11 is planar. The first seating surface 11 may be connected to the inner peripheral surface 3. As Figure 2 shown, when viewed in the direction from the first surface 10 toward the second surface 20, the first seating surface 11 is annular. The first bottom surface 12 is connected to the first seating surface 11. The first bottom surface 12 is located outside the first seating surface 11. The first bottom surface 12 is, for example, annular. The first bottom surface 12 may surround the first seating surface 11.

[0051] As Figure 2 shown, the first inclined surface 13 is connected to the first bottom surface 12. The first inclined surface 13 is located outside the first bottom surface 12. The first inclined surface 13 is, for example, annular. The first inclined surface 13 may surround the first bottom surface 12. The first land surface 14 is connected to the first inclined surface 13. The first land surface 14 is located outside the first inclined surface 13. The first land surface 14 is, for example, annular. The first land surface 14 may surround the first inclined surface 13. The first land surface 14 is connected to the outer peripheral surface 30. The ridge line between the first land surface 14 and the outer peripheral surface 30 includes a first cutting edge 1.

[0052] As Figure 2 shown, the ridge line (first ridge line 101) between the first surface 10 and the outer peripheral surface 30 includes the first cutting edge 1. The first cutting edge 1 is annular. The first cutting edge 1 includes a first main cutting edge portion 51 and a first sub-cutting edge portion 52. In the circumferential direction, the first main cutting edge portion 51 and the first sub-cutting edge portion 52 are alternately provided. In the cutting blade 100 of the first embodiment, the first cutting edge 1 has three first main cutting edge portions 51 and three first sub-cutting edge portions 52. When viewed in the direction from the first surface 10 toward the second surface 20, the first sub-cutting edge portion 52 is curved. The first sub-cutting edge portion 52 is, for example, arc-shaped. The first sub-cutting edge portion 52 has a shape that bulges outward when viewed from the inner peripheral surface 3.

[0053] As Figure 2As shown, the first ridge line 101 is substantially triangular. From another perspective, the first ridge line 101 has three first corner portions 53. The first corner portion 53 is located, for example, between the first main cutting edge portion 51 and the first sub-cutting edge portion 52. The first corner portion 53 can act as a cutting edge. When viewed in the direction from the first surface 10 toward the second surface 20, the first ridge line 101 has a shape that is rotationally symmetric about the central axis A by 120°. From another perspective, the shape of the first ridge line 101 after rotating it by 120° about the central axis A is identical to the shape of the first ridge line 101. Further, the central axis A is a straight line passing through the center of the through-hole 5 and perpendicular to the first seating surface 11.

[0054] Figure 3 is a rear schematic view showing the structure of the cutting blade 100 for a rotary cutting tool according to the first embodiment. As Figure 3 shown, the second surface 20 includes a second seating surface 21, a second bottom surface 22, a second inclined surface 23, and a second land surface 24. The second seating surface 21 is planar. The second seating surface 21 can be connected to the inner peripheral surface 3. As Figure 3 shown, when viewed in the direction from the second surface 20 toward the first surface 10, the second seating surface 21 is annular. The second bottom surface 22 is connected to the second seating surface 21. The second bottom surface 22 is located outside the second seating surface 21. The second bottom surface 22 is, for example, annular. The second bottom surface 22 can surround the second seating surface 21.

[0055] As Figure 3 shown, the second inclined surface 23 is connected to the second bottom surface 22. The second inclined surface 23 is located outside the second bottom surface 22. The second inclined surface 23 is, for example, annular. The second inclined surface 23 can surround the second bottom surface 22. The second land surface 24 is connected to the second inclined surface 23. The second land surface 24 is located outside the second inclined surface 23. The second land surface 24 is, for example, annular. The second land surface 24 can surround the second inclined surface 23. The second land surface 24 is connected to the outer peripheral surface 30. The ridge line between the second land surface 24 and the outer peripheral surface 30 includes the second cutting edge 2.

[0056] As Figure 3 shown, the ridge line (second ridge line 102) between the second surface 20 and the outer peripheral surface 30 includes the second cutting edge 2. The second cutting edge 2 is annular. The second cutting edge 2 includes a second main cutting edge portion 61 and a second sub-cutting edge portion 62. In the circumferential direction, the second main cutting edge portion 61 and the second sub-cutting edge portion 62 are alternately provided. In the cutting blade 100 of the first embodiment, the second cutting edge 2 has three second main cutting edge portions 61 and three second sub-cutting edge portions 62. When viewed in the direction from the first surface 10 toward the second surface 20, the second sub-cutting edge portion 62 is curved. The second sub-cutting edge portion 62 is, for example, arc-shaped. The second sub-cutting edge portion 62 has a shape that protrudes outward when viewed from the central axis A.

[0057] AsFigure 3 As shown, the second ridge line 102 is substantially triangular. From another perspective, the second ridge line 102 has three second corner portions 63. The second corner portion 63 is located, for example, between the second main cutting edge portion 61 and the second sub-cutting edge portion 62. The second corner portion 63 can act as a cutting edge. When viewed in the direction from the second surface 20 toward the first surface 10, the second ridge line 102 has a shape that is rotationally symmetric about the central axis A by 120°. From another perspective, the shape of the second ridge line 102 after rotating it by 120° about the central axis A is identical to the shape of the second ridge line 102. In addition, the central axis A is a straight line passing through the center of the through hole 5 and perpendicular to the second seating surface 21.

[0058] Figure 4 is a side schematic view showing the structure of the cutting insert 100 for a rotary cutting tool according to the first embodiment. As Figure 4 shown, the outer peripheral surface 30 mainly has a third seating surface 33, a fourth seating surface 34, a first flank surface 36, a second flank surface 37, a first outer peripheral surface portion 31, a second outer peripheral surface portion 32, and a third outer peripheral surface portion 35.

[0059] The third seating surface 33 is planar. The third seating surface 33 is located between the first main cutting edge portion 51 and the second sub-cutting edge portion 62. The third seating surface 33 is spaced apart from each of the first main cutting edge portion 51 and the second sub-cutting edge portion 62. The first flank surface 36 is located between the first main cutting edge portion 51 and the third seating surface 33. The first flank surface 36 is connected to each of the first main cutting edge portion 51 and the third seating surface 33. The first flank surface 36 can be planar. The first flank surface 36 can be inclined toward the through hole 5 with respect to the third seating surface 33. The inclination angle of the first flank surface 36 with respect to the third seating surface 33 is, for example, 1° or more and 3° or less.

[0060] The fourth seating surface 34 is planar. The fourth seating surface 34 is located between the second main cutting edge portion 61 and the first sub-cutting edge portion 52. The fourth seating surface 34 is spaced apart from each of the second main cutting edge portion 61 and the first sub-cutting edge portion 52. The second flank surface 37 is located between the second main cutting edge portion 61 and the fourth seating surface 34. The second flank surface 37 is connected to each of the second main cutting edge portion 61 and the fourth seating surface 34. The second flank surface 37 can be planar. The second flank surface 37 can be inclined toward the through hole 5 with respect to the fourth seating surface 34. The inclination angle of the second flank surface 37 with respect to the fourth seating surface 34 is, for example, 1° or more and 3° or less.

[0061] As Figure 4 shown, the first outer peripheral surface portion 31 is connected to the first cutting edge 1. The second outer peripheral surface portion 32 is connected to the second cutting edge 2. The third outer peripheral surface portion 35 is located between the first outer peripheral surface portion 31 and the second outer peripheral surface portion 32. The third outer peripheral surface portion 35 is connected to each of the first outer peripheral surface portion 31 and the second outer peripheral surface portion 32. As Figure 4As shown, the first outer peripheral surface 31 can be connected to the third seating surface 33 and the fourth seating surface 34 respectively. The first outer peripheral surface 31 can be connected to the first rear clearance surface 36. The second outer peripheral surface 32 can be connected to the third seating surface 33 and the fourth seating surface 34 respectively. The second outer peripheral surface 32 can be connected to the second rear clearance surface 37.

[0062] As Figure 4 shown, in the circumferential direction, the third outer peripheral surface 35 can be located between the third seating surface 33 and the fourth seating surface 34. The third outer peripheral surface 35 can be connected to the third seating surface 33 and the fourth seating surface 34 respectively. The first outer peripheral surface 31, the second outer peripheral surface 32, and the third outer peripheral surface 35 are each, for example, curved surfaces. When viewed from the central axis A, the first outer peripheral surface 31, the second outer peripheral surface 32, and the third outer peripheral surface 35 can each be, for example, curved surfaces that bulge outward.

[0063] Figure 5 is a schematic cross-sectional view along Figure 2 the V-V line. Figure 5 The cross-section shown is a cross-section (the first cross-section) that is parallel to the direction from the first surface 10 to the second surface 20 and intersects the first main cutting edge portion 51, the third seating surface 33, and the second sub-cutting edge portion 62. As Figure 5 shown, in the first cross-section, the angle (the first angle θ1) formed by the third seating surface 33 and the first seating surface 11 can be an obtuse angle, and the angle (the second angle θ2) formed by the third seating surface 33 and the second seating surface 21 can be an acute angle. The angle (the first angle θ1) formed by the third seating surface 33 and the first seating surface 11 is the angle formed by the third seating surface 33 and the first straight line D1 parallel to the first seating surface 11. The angle (the second angle θ2) formed by the third seating surface 33 and the second seating surface 21 is the angle formed by the third seating surface 33 and the second straight line D2 parallel to the second seating surface 21.

[0064] The first angle θ1 is, for example, 91° or more and 95° or less. The lower limit of the first angle θ1 is not particularly limited. For example, it can be 91.5° or more, or it can be 92° or more. The upper limit of the first angle θ1 is not particularly limited. For example, it can be 94.5° or less, or it can be 94° or less.

[0065] The second angle θ2 is, for example, 85° or more and 89° or less. The lower limit of the second angle θ2 is not particularly limited. For example, it can be 85.5° or more, or it can be 86° or more. The upper limit of the second angle θ2 is not particularly limited. For example, it can be 88.5° or less, or it can be 88° or less.

[0066] As Figure 5As shown, in the first cross-section, the first land face 14 is inclined with respect to the first flank face 36. The first inclined face 13 is inclined with respect to the first land face 14. The first inclined face 13 is inclined with respect to the first seating face 11. The first inclined face 13 is inclined upward with respect to the first seating face 11. Further, the upper side refers to the direction from the second seating face 21 toward the first seating face 11. The first land face 14 is inclined downward with respect to the first inclined face 13. Further, the lower side refers to the direction from the first seating face 11 toward the second seating face 21.

[0067] As Figure 5 shown, in the first cross-section, the second land face 24 is inclined with respect to the second outer peripheral face 32. The second inclined face 23 is inclined with respect to the second land face 24. The second inclined face 23 is inclined with respect to the second seating face 21. The second inclined face 23 is inclined downward with respect to the second seating face 21. The second land face 24 is inclined upward with respect to the second inclined face 23. In the direction from the second seating face 21 toward the first seating face 11, the second seating face 21 is located between the second bottom face 22 and the second land face 24.

[0068] Figure 6 is a schematic cross-sectional view along Figure 2 the VI-VI line. Figure 6 The cross-section shown is a cross-section (second cross-section) parallel to the direction from the first face 10 toward the second face 20 and intersecting the second main cutting edge portion 61, the fourth seating face 34, and the first sub-cutting edge portion 52. As Figure 6 shown, in the second cross-section, the angle (third angle θ3) formed by the fourth seating face 34 and the first seating face 11 may be an acute angle, and the angle (fourth angle θ4) formed by the fourth seating face 34 and the second seating face 21 may be an obtuse angle. The angle (third angle θ3) formed by the fourth seating face 34 and the first seating face 11 is the angle formed by the fourth seating face 34 and the third straight line D3 parallel to the first seating face 11. The angle (fourth angle θ4) formed by the fourth seating face 34 and the second seating face 21 is the angle formed by the fourth seating face 34 and the fourth straight line D4 parallel to the second seating face 21.

[0069] The third angle θ3 is, for example, 85° or more and 89° or less. The lower limit of the third angle θ3 is not particularly limited. For example, it may be 85.5° or more, or may be 86° or more. The upper limit of the third angle θ3 is not particularly limited. For example, it may be 88.5° or less, or may be 88° or less.

[0070] The fourth angle θ4 is, for example, 91° or more and 95° or less. The lower limit of the fourth angle θ4 is not particularly limited. For example, it may be 91.5° or more, or may be 92° or more. The upper limit of the fourth angle θ4 is not particularly limited. For example, it may be 94.5° or less, or may be 94° or less.

[0071] As shown Figure 6 in the second cross-section, the first land face 14 is inclined with respect to the first outer peripheral face 31. The first inclined face 13 is inclined with respect to the first land face 14. The first inclined face 13 is inclined with respect to the first seating face 11. The first inclined face 13 is inclined upward with respect to the first seating face 11. The first land face 14 is inclined downward with respect to the first inclined face 13. In the direction from the second seating face 21 toward the first seating face 11, the first seating face 11 is located between the first bottom face 12 and the first land face 14.

[0072] As shown Figure 6 in the second cross-section, the second land face 24 is inclined with respect to the second flank face 37. The second inclined face 23 is inclined with respect to the second land face 24. The second inclined face 23 is inclined with respect to the second seating face 21. The second inclined face 23 is inclined downward with respect to the second seating face 21. The second land face 24 is inclined upward with respect to the second inclined face 23.

[0073] Figure 7 is Figure 2 an enlarged view of region VII. As shown Figure 7 in the direction of viewing from the first face 10 toward the second face 20, at least a part of the second sub-cutting edge portion 62 is located outside the first main cutting edge portion 51. All of the second sub-cutting edge portion 62 may be located outside the first main cutting edge portion 51. The first main cutting edge portion 51 includes a first portion 71, a second portion 72, and a third portion 73. The second portion 72 is connected to the first portion 71. The third portion 73 is connected to the second portion 72. The third portion 73 is away from the first portion 71. The second portion 72 is located between the first portion 71 and the third portion 73. The second portion 72 is, for example, the ridge line of the first flank face 36 and the first face 10.

[0074] As shown Figure 7 in the direction of viewing from the first face 10 toward the second face 20, the first portion 71 and the third portion 73 are each, for example, curved. The second portion 72 is, for example, linear. The second portion 72 may be, for example, curved. In the direction of viewing from the first face 10 toward the second face 20, at least a part of the second sub-cutting edge portion 62 is located outside the second portion 72 of the first main cutting edge portion 51.

[0075] The first part 71 is smoothly connected to the second part 72. In other words, when viewed in the direction from the first face 10 towards the second face 20, the slopes of the tangents of the first part 71 and the second part 72 change continuously at the boundary between the first part 71 and the second part 72. Similarly, the third part 73 is smoothly connected to the second part 72. In other words, when viewed in the direction from the first face 10 towards the second face 20, the slopes of the tangents of the third part 73 and the second part 72 change continuously at the boundary between the third part 73 and the second part 72.

[0076] Figure 8 is Figure 3 an enlarged view of region VIII. As Figure 8 shown, when viewed in the direction from the second face 20 towards the first face 10, at least a part of the first sub-cutting edge portion 52 is located outside the second main cutting edge portion 61. The entire first sub-cutting edge portion 52 may be located outside the second main cutting edge portion 61. The second main cutting edge portion 61 includes a fourth part 74, a fifth part 75, and a sixth part 76. The fifth part 75 is connected to the fourth part 74. The sixth part 76 is connected to the fifth part 75. The sixth part 76 is away from the fourth part 74. The fifth part 75 is located between the fourth part 74 and the sixth part 76. The fifth part 75 is, for example, the ridge line of the second flank face 37 and the second face 20.

[0077] As Figure 8 shown, when viewed in the direction from the second face 20 towards the first face 10, the fourth part 74 and the sixth part 76 are each, for example, curved. The fifth part 75 is, for example, linear. The fifth part 75 may be, for example, curved. When viewed in the direction from the second face 20 towards the first face 10, at least a part of the first sub-cutting edge portion 52 is located outside the fifth part 75 of the second main cutting edge portion 61.

[0078] The fourth part 74 is smoothly connected to the fifth part 75. In other words, when viewed in the direction from the second face 20 towards the first face 10, the slopes of the tangents of the fourth part 74 and the fifth part 75 change continuously at the boundary between the fourth part 74 and the fifth part 75. Similarly, the sixth part 76 is smoothly connected to the fifth part 75. In other words, when viewed in the direction from the second face 20 towards the first face 10, the slopes of the tangents of the sixth part 76 and the fifth part 75 change continuously at the boundary between the sixth part 76 and the fifth part 75.

[0079] (Second Embodiment)

[0080] Next, the structure of the rotary cutting tool according to the second embodiment of the present invention will be described.

[0081] Figure 9 is a perspective view showing the structure of the rotary cutting tool according to the second embodiment. As Figure 9 shown, the rotary cutting tool 90 according to the second embodiment is, for example, a milling cutter. The rotary cutting tool 90 according to the second embodiment has a main body portion 80, a cutting blade 100, and a mounting screw 91. The rotary cutting tool 90 rotates about a rotation axis B. The main body portion 80 holds the cutting blade 100. The cutting blade 100 is, for example, the cutting blade 100 according to the first embodiment. In the rotary cutting tool 90 according to the second embodiment, four cutting blades 100 are arranged around the rotation axis B.

[0082] The main body portion 80 has a front end face 81, a rear end face 82, and an outer peripheral side face 86. The front end face 81 is a portion facing the material to be cut. The rear end face 82 faces the front end face 81. The rear end face 82 is, for example, mounted on a tool holder. The outer peripheral side face 86 is connected to each of the front end face 81 and the rear end face 82.

[0083] A blade arrangement groove 85 is formed in the main body portion 80. The blade arrangement groove 85 has a first side wall surface 83 and a second side wall surface 84. The first side wall surface 83 is inclined so as to intersect the second side wall surface 84 in a substantially perpendicular direction. The first side wall surface 83 is connected to each of the front end face 81 and the outer peripheral side face 86. The first side wall surface 83 is away from the rear end face 82. Similarly, the second side wall surface 84 is connected to each of the front end face 81 and the outer peripheral side face 86. The second side wall surface 84 is away from the rear end face 82.

[0084] The first side wall surface 83 is in contact with the third seating surface 33 and the fourth seating surface 34 of the cutting blade 100. The first side wall surface 83 can be in contact with two third seating surfaces 33 that are in a position rotationally symmetric about the central axis A of the cutting blade 100 by 120°. The second side wall surface 84 is in contact with the second seating surface 21 of the cutting blade 100. The mounting screw 91 is arranged in the through hole 5 of the cutting blade 100. Using the mounting screw 91, the cutting blade 100 is mounted on the main body portion 80. Thus, the cutting blade 100 is fixed to the main body portion 80.

[0085] (Third Embodiment)

[0086] Next, the structure of the cutting blade 100 for a rotary cutting tool according to the third embodiment of the present invention will be described.

[0087] Figure 10 is a perspective view showing the structure of the cutting blade 100 for a rotary cutting tool according to the third embodiment. As Figure 10As shown, the cutting blade 100 for a rotary cutting tool according to the third embodiment mainly has a first surface 10, a second surface 20, an outer peripheral surface 30, and an inner peripheral surface 3. The second surface 20 faces the first surface 10. The outer peripheral surface 30 is connected to each of the first surface 10 and the second surface 20. Similarly, the inner peripheral surface 3 is connected to each of the first surface 10 and the second surface 20. The outer peripheral surface 30 is on the outside of the inner peripheral surface 3. The inner peripheral surface 3 forms a through-hole 5.

[0088] Figure 11 is a plan view showing the structure of the cutting blade 100 for a rotary cutting tool according to the third embodiment. As Figure 11 shown, the first surface 10 includes a first seating surface 11, a third inclined surface 15, a first inclined surface 13, and a first land surface 14. The first seating surface 11 is planar. The first seating surface 11 can be connected to the inner peripheral surface 3. As Figure 11 shown, when viewed in the direction from the first surface 10 toward the second surface 20, the first seating surface 11 is annular. The third inclined surface 15 is connected to the first seating surface 11. The third inclined surface 15 is located outside the first seating surface 11.

[0089] As Figure 11 shown, the first inclined surface 13 is connected to the third inclined surface 15. The first inclined surface 13 is located outside the third inclined surface 15. The first land surface 14 is connected to the first inclined surface 13. The first land surface 14 is located outside the first inclined surface 13. The first land surface 14 is connected to the outer peripheral surface 30. The ridge line between the first land surface 14 and the outer peripheral surface 30 forms a first cutting edge 1. The first seating surface 11 can be connected to the outer peripheral surface 30. The ridge line between the first seating surface 11 and the outer peripheral surface 30 forms a first straight portion 54.

[0090] As Figure 11 shown, the ridge line (first ridge line 101) between the first surface 10 and the outer peripheral surface 30 includes the first cutting edge 1 and the first straight portion 54. The first cutting edge 1 includes a first major cutting edge portion 51 and a first minor cutting edge portion 52. In the circumferential direction, the first major cutting edge portion 51, the first minor cutting edge portion 52, and the first straight portion 54 are alternately arranged. In the cutting blade 100 of the third embodiment, the first cutting edge 1 has two first major cutting edge portions 51 and two first minor cutting edge portions 52. When viewed in the direction from the first surface 10 toward the second surface 20, the first minor cutting edge portion 52 is curved. The first minor cutting edge portion 52 is, for example, arc-shaped. The first minor cutting edge portion 52 has a shape that protrudes outward when viewed from the inner peripheral surface 3.

[0091] As Figure 11As shown, the ridge line (the first ridge line 101) of the first surface 10 and the outer peripheral surface 30 is substantially rectangular. From another perspective, the first ridge line 101 has four first corner portions 53. The first corner portion 53 is located, for example, between the first main cutting edge portion 51 and the first straight portion 54. When observed in the direction from the first surface 10 toward the second surface 20, the first ridge line 101 has a shape that is rotationally symmetric about the central axis A by 180°. From another perspective, the shape of the first ridge line 101 after rotating it by 180° about the central axis A coincides with the shape of the first ridge line 101. In addition, the central axis A is a straight line passing through the center of the through-hole 5 and perpendicular to the first seating surface 11.

[0092] Figure 12 is a rear schematic view showing the structure of the cutting blade 100 for a rotary cutting tool according to the third embodiment. As Figure 12 shown, the second surface 20 includes a second seating surface 21, a fourth inclined surface 25, a second inclined surface 23, and a second land surface 24. The second seating surface 21 is planar. The second seating surface 21 can be connected to the inner peripheral surface 3. As Figure 12 shown, when observed in the direction from the second surface 20 toward the first surface 10, the second seating surface 21 is annular. The fourth inclined surface 25 is connected to the second seating surface 21. The fourth inclined surface 25 is located outside the second seating surface 21.

[0093] As Figure 12 shown, the second inclined surface 23 is connected to the fourth inclined surface 25. The second inclined surface 23 is located outside the fourth inclined surface 25. The second land surface 24 is connected to the second inclined surface 23. The second land surface 24 is located outside the second inclined surface 23. The second land surface 24 is connected to the outer peripheral surface 30. The ridge line between the second land surface 24 and the outer peripheral surface 30 forms the second cutting edge 2. The second seating surface 21 can be connected to the outer peripheral surface 30. The ridge line between the second seating surface 21 and the outer peripheral surface 30 forms the second straight portion 64.

[0094] As Figure 12 shown, the ridge line (the second ridge line 102) of the second surface 20 and the outer peripheral surface 30 includes the second cutting edge 2 and the second straight portion 64. The second cutting edge 2 includes a second main cutting edge portion 61 and a second sub-cutting edge portion 62. In the circumferential direction, the second main cutting edge portion 61, the second sub-cutting edge portion 62, and the second straight portion 64 are alternately arranged. In the cutting blade 100 of the third embodiment, the second cutting edge 2 has two second main cutting edge portions 61 and two second sub-cutting edge portions 62. When observed in the direction from the second surface 20 toward the first surface 10, the second sub-cutting edge portion 62 is curved. The second sub-cutting edge portion 62 is, for example, arc-shaped. The second sub-cutting edge portion 62 has a shape that bulges outward when observed from the inner peripheral surface 3.

[0095] As Figure 12As shown, the ridge line (the second ridge line 102) of the second surface 20 and the outer peripheral surface 30 is substantially rectangular. From another perspective, the second ridge line 102 has four second corner portions 63. The second corner portion 63 is located, for example, between the second main cutting edge portion 61 and the second straight portion 64. When viewed in the direction from the second surface 20 toward the first surface 10, the second ridge line 102 has a shape that is rotationally symmetric about the central axis A by 180°. From another perspective, the shape of the second ridge line 102 after rotating it by 180° about the central axis A is identical to the shape of the second ridge line 102. Further, the central axis A is a straight line passing through the center of the through-hole 5 and perpendicular to the second seating surface 21.

[0096] Figure 13 It is a side schematic view showing the structure of the cutting blade 100 for a rotary cutting tool according to the third embodiment. As Figure 13 shown, the outer peripheral surface 30 mainly has a third seating surface 33, a fourth seating surface 34, a first outer peripheral surface portion 31, a second outer peripheral surface portion 32, and a fifth seating surface 38. The third seating surface 33 is planar. The third seating surface 33 is located between the first main cutting edge portion 51 and the second sub-cutting edge portion 62. The third seating surface 33 is connected to the first main cutting edge portion 51. The third seating surface 33 is away from the second sub-cutting edge portion 62. The fourth seating surface 34 is planar. The fourth seating surface 34 is located between the second main cutting edge portion 61 and the first sub-cutting edge portion 52. The fourth seating surface 34 is connected to the second main cutting edge portion 61. The fourth seating surface 34 is away from the first sub-cutting edge portion 52. The fifth seating surface 38 is planar. The fifth seating surface 38 is located between the first straight portion 54 and the second straight portion 64. The fifth seating surface 38 is connected to the first straight portion 54 and the second straight portion 64.

[0097] As Figure 13 shown, the first outer peripheral surface portion 31 is connected to the first cutting edge 1. The second outer peripheral surface portion 32 is connected to the second cutting edge 2. The first outer peripheral surface portion 31 may be connected to each of the fifth seating surface 38, the third seating surface 33, and the fourth seating surface 34. The first outer peripheral surface portion 31 may be located between the fourth seating surface 34 and the first sub-cutting edge portion 52. The second outer peripheral surface portion 32 may be connected to each of the fifth seating surface 38, the third seating surface 33, and the fourth seating surface 34. The second outer peripheral surface portion 32 may be located between the third seating surface 33 and the second sub-cutting edge portion 62. Each of the first outer peripheral surface portion 31 and the second outer peripheral surface portion 32 is, for example, curved. When viewed from the central axis A, each of the first outer peripheral surface portion 31 and the second outer peripheral surface portion 32 may be, for example, a curved surface that bulges outward.

[0098] Figure 14 is a cross-sectional schematic view along Figure 11 [[ID=1"]]the XIV-XIV line. Figure 14The cross-section shown is a cross-section (first cross-section) parallel to the direction from the first surface 10 towards the second surface 20 and intersecting the first major cutting edge portion 51, the third seating surface 33, and the second minor cutting edge portion 62. As Figure 14 shown, in the first cross-section, the angle (first angle θ1) formed by the third seating surface 33 and the first seating surface 11 may be an obtuse angle, and the angle (second angle θ2) formed by the third seating surface 33 and the second seating surface 21 may be an acute angle. The angle (first angle θ1) formed by the third seating surface 33 and the first seating surface 11 is the angle formed by the third seating surface 33 and the first straight line D1 along the first seating surface 11. The angle (second angle θ2) formed by the third seating surface 33 and the second seating surface 21 is the angle formed by the third seating surface 33 and the second straight line D2 parallel to the second seating surface 21.

[0099] The first angle θ1 is, for example, 91° or more and 95° or less. The lower limit of the first angle θ1 is not particularly limited. For example, it may be 91.5° or more, or it may be 92° or more. The upper limit of the first angle θ1 is not particularly limited. For example, it may be 94.5° or less, or it may be 94° or less.

[0100] The second angle θ2 is, for example, 85° or more and 89° or less. The lower limit of the second angle θ2 is not particularly limited. For example, it may be 85.5° or more, or it may be 86° or more. The upper limit of the second angle θ2 is not particularly limited. For example, it may be 88.5° or less, or it may be 88° or less.

[0101] As Figure 14 shown, the first inclined surface 13 is inclined with respect to the first land surface 14. The first inclined surface 13 is inclined with respect to the third inclined surface 15. The third inclined surface 15 is inclined with respect to the first seating surface 11. The third inclined surface 15 is inclined upward with respect to the first seating surface 11. The first inclined surface 13 is inclined upward with respect to the first seating surface 11. In addition, the upper side refers to the direction from the second seating surface 21 towards the first seating surface 11. The first land surface 14 is inclined downward with respect to the first inclined surface 13. In the first cross-section, the fourth inclined surface 25 is inclined downward with respect to the second seating surface 21. In addition, the lower side refers to the direction from the first seating surface 11 towards the second seating surface 21.

[0102] Figure 15 is a schematic cross-sectional view along the Figure 11 XV - XV line. Figure 15 The cross-section shown is a cross-section (second cross-section) parallel to the direction from the first surface 10 towards the second surface 20 and intersecting the second major cutting edge portion 61, the fourth seating surface 34, and the first minor cutting edge portion 52. As Figure 15As shown, in the second cross-section, the angle formed by the fourth seating surface 34 and the first seating surface 11 (the third angle θ3) can be an acute angle, and the angle formed by the fourth seating surface 34 and the second seating surface 21 (the fourth angle θ4) can be an obtuse angle. The angle formed by the fourth seating surface 34 and the first seating surface 11 (the third angle θ3) is the angle formed by the fourth seating surface 34 and the third straight line D3 parallel to the first seating surface 11. The angle formed by the fourth seating surface 34 and the second seating surface 21 (the fourth angle θ4) is the angle formed by the fourth seating surface 34 and the fourth straight line D4 along the second seating surface 21.

[0103] The third angle θ3 is, for example, 85° or more and 89° or less. The lower limit of the third angle θ3 is not particularly limited. For example, it can be 85.5° or more, or it can be 86° or more. The upper limit of the third angle θ3 is not particularly limited. For example, it can be 88.5° or less, or it can be 88° or less.

[0104] The fourth angle θ4 is, for example, 91° or more and 95° or less. The lower limit of the fourth angle θ4 is not particularly limited. For example, it can be 91.5° or more, or it can be 92° or more. The upper limit of the fourth angle θ4 is not particularly limited. For example, it can be 94.5° or less, or it can be 94° or less.

[0105] As Figure 15 shown, in the second cross-section, the first land face 14 is inclined with respect to the first outer peripheral face 31. The first inclined face 13 is inclined with respect to the first land face 14. The first inclined face 13 is inclined with respect to the first seating face 11. The first inclined face 13 is inclined upward with respect to the first seating face 11. In the second cross-section, the fourth inclined face 25 is inclined with respect to the second seating face 21. The second inclined face 23 is inclined with respect to the fourth inclined face 25. The fourth inclined face 25 is inclined downward with respect to the second seating face 21. The second inclined face 23 is inclined downward with respect to the second seating face 21.

[0106] Figure 16 is Figure 11 an enlarged view of region XVI. As Figure 16 shown, when viewed in the direction from the first face 10 toward the second face 20, at least a part of the second sub-cutting edge portion 62 is located outside the first main cutting edge portion 51. The entire second sub-cutting edge portion 62 can be located outside the first main cutting edge portion 51. The first main cutting edge portion 51 includes a first portion 71 and a second portion 72. The second portion 72 is connected to the first portion 71. When viewed in the direction from the first face 10 toward the second face 20, the first portion 71 is, for example, curved. The second portion 72 is, for example, linear. The second portion 72 can, for example, be curved.

[0107] When viewed in the direction from the first face 10 toward the second face 20, at least a part of the second sub-cutting edge portion 62 is located outside the second part 72 of the first main cutting edge portion 51. The first part 71 and the second part 72 are smoothly connected. From another viewpoint, when viewed in the direction from the first face 10 toward the second face 20, the slope of the tangent line of the first part 71 and the slope of the tangent line of the second part 72 change continuously at the boundary between the first part 71 and the second part 72.

[0108] Figure 17 is Figure 12 an enlarged view of region XVII. As Figure 17 shown, when viewed in the direction from the second face 20 toward the first face 10, at least a part of the first sub-cutting edge portion 52 is located outside the second main cutting edge portion 61. The entire first sub-cutting edge portion 52 may be located outside the second main cutting edge portion 61. The second main cutting edge portion 61 includes a fourth part 74 and a fifth part 75. The fifth part 75 is connected to the fourth part 74. When viewed in the direction from the second face 20 toward the first face 10, the fourth part 74 is, for example, curved. The fifth part 75 is, for example, linear. The fifth part 75 may be, for example, curved.

[0109] When viewed in the direction from the second face 20 toward the first face 10, at least a part of the first sub-cutting edge portion 52 is located outside the fifth part 75 of the second main cutting edge portion 61. The fourth part 74 and the fifth part 75 are smoothly connected. From another viewpoint, when viewed in the direction from the second face 20 toward the first face 10, the slope of the tangent line of the fourth part 74 and the slope of the tangent line of the fifth part 75 change continuously at the boundary between the fourth part 74 and the fifth part 75.

[0110] (Fourth Embodiment)

[0111] Next, the structure of the rotary cutting tool according to the fourth embodiment of the present invention will be described.

[0112] Figure 18 is a perspective view showing the structure of the rotary cutting tool according to the fourth embodiment. As Figure 18 shown, the rotary cutting tool 90 according to the fourth embodiment is, for example, a milling cutter. The rotary cutting tool 90 according to the fourth embodiment has a main body portion 80, a cutting insert 100, and a mounting screw 91. The rotary cutting tool 90 rotates about a rotation axis B. The main body portion 80 holds the cutting insert 100. The cutting insert 100 is, for example, the cutting insert 100 according to the third embodiment. In the rotary cutting tool 90 according to the fourth embodiment, three cutting inserts 100 are arranged at equal intervals about the rotation axis B.

[0113] The main body portion 80 has a front end face 81, a rear end face 82, and an outer peripheral side face 86. The front end face 81 is the portion facing the material to be cut. The rear end face 82 faces the front end face 81. The rear end face 82 is mounted on a machine tool, for example. The outer peripheral side face 86 is connected to each of the front end face 81 and the rear end face 82.

[0114] A blade mounting groove 85 is formed in the main body portion 80. The blade mounting groove 85 has a first side wall face 83 and a second side wall face 84. The first side wall face 83 is inclined to intersect the second side wall face 84 in a substantially perpendicular direction. The first side wall face 83 is connected to each of the front end face 81 and the outer peripheral side face 86. The first side wall face 83 is away from the rear end face 82. Similarly, the second side wall face 84 is connected to each of the front end face 81 and the outer peripheral side face 86. The second side wall face 84 is away from the rear end face 82.

[0115] The first side wall face 83 abuts against the fourth seating face 34 and the fifth seating face 38 of the cutting blade 100. The first side wall face 83 may abut against the third seating face 33 of the cutting blade 100. The second side wall face 84 abuts against the second seating face 21 of the cutting blade 100. A mounting screw 91 is disposed in the through hole 5 of the cutting blade 100. Using the mounting screw 91, the cutting blade 100 is mounted on the main body portion 80. Thus, the cutting blade 100 is fixed to the main body portion 80.

[0116] Next, the effects of the cutting blade 100 for a rotary cutting tool and the rotary cutting tool 90 according to the above-described embodiment will be described.

[0117] Figure 19 It is a cross-sectional schematic view showing a cutting state. Figure 19 The left side of shows the cutting state when the cutting angle θ5 is about 45°. Figure 19 The right side of shows the cutting state when the cutting angle θ5 is about 25°. In Figure 19 shows the thickness of the chip 94 when the material 95 to be cut is cut using the cutting blade 100. The cutting blade 100 rotates about the rotation axis B of the rotary cutting tool 90 and cuts the material 95 to be cut in the direction perpendicular to the paper surface. At the same time, the cutting blade 100 feeds from the left side to the right side of the paper surface. The distance f z is the feed per edge. The thickness of the chip 94 is obtained as sin(θ5) × f z When the cutting angle θ5 is 45°, the thickness h1 of the chip 94 is about 0.71 × f z . When the cutting angle θ5 is 25°, the thickness h2 of the chip 94 is about 0.42 × f z . As Figure 19As shown, if the cutting-in angle θ5 becomes smaller, the thickness of the chip 94 becomes thinner. As a result, the cutting resistance per unit length borne by the first cutting edge 1 can be reduced. Further, since the chip 94 is obtained by plastic deformation of the work material 95, heat is generated from the chip 94. The heat generated accompanying the plastic deformation diffuses from the interface near the first cutting edge 1 of the cutting insert 100 in contact with the chip 94 and from the interface between the chip 94 and the work material 95. If the cutting-in angle θ5 becomes smaller, the area of these interfaces increases, and thus the temperature rise near the first cutting edge 1 can be suppressed.

[0118] Figure 20 is a schematic view showing a state in which the work material 95 is inclinedly machined using the cutting insert 100 for a rotary cutting tool. In Figure 20 , the line segment L indicated by a dashed line shows a case where the first secondary cutting edge portion 52 is linear. As Figure 20 shown, compared with the case where the first secondary cutting edge portion 52 is linear, in the case where the first secondary cutting edge portion 52 is curved, the cutting-in angle θ5 of the first secondary cutting edge portion 52 can be reduced. In this case, the thickness of the chip 94 can be made thinner. As a result, the cutting resistance can be reduced. Therefore, the temperature rise of the first secondary cutting edge portion 52 can be suppressed.

[0119] According to the cutting insert 100 for a rotary cutting tool according to the above-described embodiment, the ridge line between the first surface 10 and the outer peripheral surface 30 includes the first cutting edge 1. The ridge line between the second surface 20 and the outer peripheral surface 30 includes the second cutting edge 2. The first surface 10 includes the planar first seating surface 11. The second surface 20 includes the planar second seating surface 21. The first cutting edge 1 has a first main cutting edge portion 51 and a first secondary cutting edge portion 52. The second cutting edge 2 has a second main cutting edge portion 61 and a second secondary cutting edge portion 62. When viewed in the direction from the first surface 10 toward the second surface 20, the first secondary cutting edge portion 52 and the second secondary cutting edge portion 62 are each curved. Therefore, compared with the case where the first secondary cutting edge portion 52 and the second secondary cutting edge portion 62 are each linear, the cutting-in angle θ5 can be reduced. In this case, the thickness of the chip 94 can be made thinner. As a result, the cutting resistance can be reduced. Therefore, the temperature rise of each of the first secondary cutting edge portion 52 and the second secondary cutting edge portion 62 can be suppressed. Therefore, the life of the cutting insert 100 can be extended.

[0120] Further, according to the cutting insert 100 for a rotary cutting tool according to the above-described embodiment, the outer peripheral surface 30 includes the planar third seating surface 33. The cutting insert 100 is constrained by the main body portion 80 by bringing the third seating surface 33 into contact with the main body portion 80. Compared with the case where the third seating surface 33 is curved, in the case where the third seating surface 33 is planar, the cutting insert 100 can be stably fixed to the main body portion 80 even when a large cutting load is applied to the cutting insert 100.

[0121] Moreover, in the cutting blade 100 for a rotary cutting tool according to the above-described embodiment, when viewed in the direction from the first surface 10 toward the second surface 20, at least a part of the second secondary cutting edge portion 62 is located outside the first main cutting edge portion 51, and at least a part of the first secondary cutting edge portion 52 is located outside the second main cutting edge portion 61.

[0122] As Figure 20 shown, when the cutting blade 100 is mounted on the main body portion 80, the first main cutting edge portion 51 is arranged closer to the outer peripheral side than the first secondary cutting edge portion 52. Therefore, the cutting load on the first main cutting edge portion 51 is larger than that on the first secondary cutting edge portion 52. Similarly, the second main cutting edge portion 61 is arranged closer to the outer peripheral side than the second secondary cutting edge portion 62. Therefore, the cutting load on the second main cutting edge portion 61 is larger than that on the second secondary cutting edge portion 62. When viewed in the direction from the first surface 10 toward the second surface 20, when at least a part of the second secondary cutting edge portion 62 is located outside the first main cutting edge portion 51 and at least a part of the first secondary cutting edge portion 52 is located outside the second main cutting edge portion 61, compared with the case where at least a part of the second secondary cutting edge portion 62 is located inside the first main cutting edge portion 51 and at least a part of the first secondary cutting edge portion 52 is located inside the second main cutting edge portion 61, the strength of each of the first main cutting edge portion 51 and the second main cutting edge portion 61 can be improved. Therefore, breakage of each of the first main cutting edge portion 51 and the second main cutting edge portion 61 can be suppressed.

[0123] As Figure 20 shown, when the cutting blade 100 is used to cut the workpiece 95, a force is applied to the first cutting edge 1 in contact with the workpiece 95 in the direction of arrow C. The cutting blade 100 is mounted on the main body portion 80 using a mounting screw 91. Therefore, a force in the direction of arrow D acts on a portion on the side opposite to the first cutting edge 1 with respect to the mounting screw 91. As a result, the cutting blade 100 may float in the direction of arrow D.

[0124] In the cutting blade 100 for a rotary cutting tool according to the above-described embodiment, in a cross section parallel to the direction from the first surface 10 toward the second surface 20 and intersecting the first main cutting edge portion 51, the third seating surface 33, and the second secondary cutting edge portion 62, the angle formed by the third seating surface 33 and the first seating surface 11 may be an obtuse angle, and the angle formed by the third seating surface 33 and the second seating surface 21 may be an acute angle. Thus, when viewed in the direction of arrow D, the cutting blade 100 can be arranged in the blade mounting groove 85 such that the first side wall surface 83 of the main body portion 80 covers the third seating surface 33. Therefore, movement of the third seating surface 33 in the direction of arrow D can be suppressed by the first side wall surface 83. As a result, floating of the cutting blade 100 from the blade mounting groove 85 can be suppressed.

[0125] If the angle formed by the third seating surface 33 and the first seating surface 11 is excessively reduced, the first side wall surface 83 of the main body portion 80 cannot cover the third seating surface 33. According to the cutting blade 100 for a rotary cutting tool according to the above-described embodiment, in a cross section parallel to the direction from the first surface 10 toward the second surface 20 and intersecting the first main cutting edge portion 51, the third seating surface 33, and the second sub-cutting edge portion 62, the angle formed by the third seating surface 33 and the first seating surface 11 may be 91° or more. Thereby, it is possible to effectively suppress the floating of the cutting blade 100.

[0126] If the angle formed by the third seating surface 33 and the first seating surface 11 is excessively increased, the third seating surface 33 is likely to interfere with the workpiece 95. According to the cutting blade 100 for a rotary cutting tool according to the above-described embodiment, in a cross section parallel to the direction from the first surface 10 toward the second surface 20 and intersecting the first main cutting edge portion 51, the third seating surface 33, and the second sub-cutting edge portion 62, the angle formed by the third seating surface 33 and the first seating surface 11 may be 95° or less. Thereby, it is possible to suppress the interference between the third seating surface 33 and the workpiece 95.

[0127] According to the cutting blade 100 for a rotary cutting tool according to the above-described embodiment, the outer peripheral surface 30 may include a relief surface 36 located between the first main cutting edge portion 51 and the third seating surface 33. The relief surface 36 may be inclined with respect to the third seating surface 33. Thereby, when the third seating surface 33 is mounted on the main body portion 80, it is possible to suppress the interference between the relief surface 36 and the main body portion 80.

[0128] According to the cutting blade 100 for a rotary cutting tool according to the above-described embodiment, the first main cutting edge portion 51 may include a first portion 71, a second portion 72 connected to the first portion 71, and a third portion 73 remote from the first portion 71 and connected to the second portion 72. The second main cutting edge portion 61 may include a fourth portion 74, a fifth portion 75 connected to the fourth portion 74, and a sixth portion 76 remote from the fourth portion 74 and connected to the fifth portion 75. Each of the first portion 71, the third portion 73, the fourth portion 74, and the sixth portion 76 may be curved. Thereby, compared with the case where each of the first portion 71, the third portion 73, the fourth portion 74, and the sixth portion 76 is linear, it is possible to reduce the cutting-in angle θ5 of each of the first portion 71, the third portion 73, the fourth portion 74, and the sixth portion 76. As a result, it is possible to suppress the temperature rise of each of the first portion 71, the third portion 73, the fourth portion 74, and the sixth portion 76. Therefore, it is possible to extend the life of the cutting blade 100.

[0129] According to the cutting insert 100 for a rotary cutting tool according to the above-described embodiment, each of the second portion 72 and the fifth portion 75 can be curved. Thus, compared with the case where each of the second portion 72 and the fifth portion 75 is linear, the cutting-in angle θ5 of each of the second portion 72 and the fifth portion 75 can be reduced. As a result, the temperature rise of each of the second portion 72 and the fifth portion 75 can be suppressed. Therefore, the life of the cutting insert 100 can be extended.

[0130] The embodiments disclosed herein are illustrative in all respects and should be considered non-restrictive. The scope of the present invention is not the above-described embodiments, but is shown by the claims, and includes all modifications within the meaning and scope equivalent to the claims.

[0131] Explanation of reference numerals

[0132] 1 First cutting edge, 2 Second cutting edge, 3 Inner circumferential surface, 5 Through hole, 10 First surface, 11 First seating surface, 12 First bottom surface, 13 First inclined surface, 14 First land surface, 15 Third inclined surface, 20 Second surface, 21 Second seating surface, 22 Second bottom surface, 23 Second inclined surface, 24 Second land surface, 25 Fourth inclined surface, 30 Outer circumferential surface, 31 First outer circumferential portion, 32 Second outer circumferential portion, 33 Third seating surface, 34 Fourth seating surface, 35 Third outer circumferential portion, 36 Relief surface (first relief surface), 37 Second relief surface, 38 Fifth seating surface, 51 First major cutting edge portion, 52 First minor cutting edge portion, 53 First corner portion, 54 First straight portion, 61 Second major cutting edge portion, 62 Second minor cutting edge portion, 63 Second corner portion, 64 Second straight portion, 71 First portion, 72 Second portion, 73 Third portion, 74 Fourth portion, 75 Fifth portion, 76 Sixth portion, 80 Main body portion, 81 Front end surface, 82 Rear end surface, 83 First side wall surface, 84 Second side wall surface, 85 Insert mounting groove, 86 Outer peripheral side surface, 90 Rotary cutting tool, 91 Mounting screw, 94 Chip, 95 Workpiece material, 100 Cutting insert for rotary cutting tool (cutting insert), 101 First ridge line, 102 Second ridge line, A Central axis, B Rotation axis, C, D Arrows, D1 First straight line, D2 Second straight line, D3 Third straight line, D4 Fourth straight line, L Line segment, f z Distance, h1, h2 Thickness, θ1 First angle, θ2 Second angle, θ3 Third angle, θ4 Fourth angle, θ5 Cutting-in angle.

Claims

1. A cutting blade for a rotary cutting tool, having: a first surface; a second surface opposite to the first surface; an outer peripheral surface connected to each of the first surface and the second surface; and an inner peripheral surface located inside the outer peripheral surface and forming a through-hole, a ridge line of the first surface and the outer peripheral surface includes a first cutting edge, a ridge line of the second surface and the outer peripheral surface includes a second cutting edge, the first surface includes a planar first seating surface, the second surface includes a planar second seating surface, the first cutting edge has a first main cutting edge portion and a first sub-cutting edge portion, the second cutting edge has a second main cutting edge portion and a second sub-cutting edge portion, when viewed in a direction from the first surface toward the second surface, at least a part of the second sub-cutting edge portion is located outside the first main cutting edge portion, and at least a part of the first sub-cutting edge portion is located outside the second main cutting edge portion, when viewed in a direction from the first surface toward the second surface, each of the first sub-cutting edge portion and the second sub-cutting edge portion is curved, the outer peripheral surface includes a planar third seating surface, in a cross-section parallel to the direction from the first surface toward the second surface and intersecting the first main cutting edge portion, the third seating surface, and the second sub-cutting edge portion, an angle formed by the third seating surface and the first seating surface is an obtuse angle, and an angle formed by the third seating surface and the second seating surface is an acute angle, the outer peripheral surface includes a clearance surface located between the first main cutting edge portion and the third seating surface, the clearance surface is inclined toward the through-hole side with respect to the third seating surface.

2. The cutting blade for a rotary cutting tool according to claim 1, wherein in a cross-section parallel to the direction from the first surface toward the second surface and intersecting the first main cutting edge portion, the third seating surface, and the second sub-cutting edge portion, an angle formed by the third seating surface and the first seating surface is 91° or more and 95° or less.

3. The cutting blade for a rotary cutting tool according to claim 1 or 2, wherein when viewed in a direction from the first surface toward the second surface, a ridge line of the first surface and the outer peripheral surface has a shape rotationally symmetric about a central axis by 120°.

4. The cutting blade for a rotary cutting tool according to claim 1 or 2, wherein the first main cutting edge portion includes a first portion, a second portion connected to the first portion, and a third portion remote from the first portion and connected to the second portion, the second main cutting edge portion includes a fourth portion, a fifth portion connected to the fourth portion, and a sixth portion remote from the fourth portion and connected to the fifth portion, each of the first portion, the third portion, the fourth portion, and the sixth portion is curved.

5. The cutting blade for a rotary cutting tool according to claim 4, wherein each of the second portion and the fifth portion is linear.

6. The cutting blade for a rotary cutting tool according to claim 4, wherein each of the second portion and the fifth portion is curved.

7. A cutting blade for a rotary cutting tool, having: a first surface; The second surface, which is opposite to the first surface; and The outer peripheral surface, which is connected to each of the first surface and the second surface, The ridge line of the first surface and the outer peripheral surface includes a first cutting edge and a first straight portion, The ridge line of the second surface and the outer peripheral surface includes a second cutting edge and a second straight portion, The first surface includes a planar first seating surface, The second surface includes a planar second seating surface, The first cutting edge includes a first main cutting edge portion and a first sub-cutting edge portion, The second cutting edge includes a second main cutting edge portion and a second sub-cutting edge portion, When viewed in the direction from the first surface toward the second surface, at least a part of the second sub-cutting edge portion is located outside the first main cutting edge portion, and at least a part of the first sub-cutting edge portion is located outside the second main cutting edge portion, When viewed in the direction from the first surface toward the second surface, the first sub-cutting edge portion and the second sub-cutting edge portion are each curved, The outer peripheral surface includes: A third seating surface, which is planar, located between the first main cutting edge portion and the second sub-cutting edge portion, and connected to the first main cutting edge portion; A fourth seating surface, which is planar, located between the second main cutting edge portion and the first sub-cutting edge portion, and connected to the second main cutting edge portion; and A fifth seating surface, which is planar, located between the first straight portion and the second straight portion, and connected to the first straight portion and the second straight portion, In a cross-section parallel to the direction from the first surface toward the second surface and intersecting the first main cutting edge portion, the third seating surface, and the second sub-cutting edge portion, the angle formed by the third seating surface and the first seating surface is an obtuse angle, and the angle formed by the third seating surface and the second seating surface is an acute angle, When viewed in the direction from the first surface toward the second surface, in the circumferential direction, the first main cutting edge portion, the first sub-cutting edge portion, and the first straight portion are alternately arranged, When viewed in the direction from the second surface toward the first surface, in the circumferential direction, the second main cutting edge portion, the second sub-cutting edge portion, and the second straight portion are alternately arranged, When viewed in the direction from the first surface toward the second surface, the ridge line of the first surface and the outer peripheral surface has a shape rotationally symmetric about the central axis by 180°.

8. The cutting insert for a rotary cutting tool according to claim 7, wherein, In a cross-section parallel to the direction from the first surface toward the second surface and intersecting the first main cutting edge portion, the third seating surface, and the second sub-cutting edge portion, the angle formed by the third seating surface and the first seating surface is 91° or more and 95° or less.

9. The cutting insert for a rotary cutting tool according to claim 7 or 8, wherein, The first main cutting edge portion includes a first portion and a second portion connected to the first portion, The second main cutting edge portion includes a fourth portion and a fifth portion connected to the fourth portion, The first portion and the fourth portion are each curved.

10. The cutting insert for a rotary cutting tool according to claim 9, wherein, The second portion and the fifth portion are each straight.

11. The cutting blade for a rotary cutting tool according to claim 9, wherein the second part and the fifth part are each curved.

12. A rotary cutting tool, comprising: a cutting blade for a rotary cutting tool according to any one of claims 1 to 11; and a main body portion that holds the cutting blade for a rotary cutting tool.

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