Cutting insert

Abstract

A cutting insert includes a top surface, a bottom surface, and an outer peripheral surface. A ridgeline between the top surface and the outer peripheral surface surface includes a first cutting edge, a corner cutting edge, and a second cutting edge. A protrusion is provided on the top surface. When viewed in a direction perpendicular to the bottom surface, the protrusion extends along a bisector of an angle formed by the first cutting edge and the second cutting edge. When viewed in a first direction, an intersection of the corner cutting edge and the bisector is defined as a reference point. In a first cross-section that is perpendicular to the bisector and in which the distance from the reference point is 0.5 mm, the distance between the first cutting edge and the protrusion in the direction perpendicular to the bottom surface is defined as a first distance. In a second cross-section that is perpendicular to the bisector and in which the distance from the reference point is 1.5 mm, the distance between the first cutting edge and the protrusion in the direction perpendicular to the bottom surface is defined as a third distance. The third distance is greater than the first distance. A ratio of the height of the protrusion to the width of the protrusion in the second cross-section is less than a ratio of the height of the protrusion to the width of the protrusion in the first cross-section.

Description

Technical Field

[0001] This disclosure relates to cutting inserts.

Background Art

[0002] WO 2015 / 046558 (Patent Document 1) describes a cutting insert. A protrusion is provided on the upper surface of the cutting insert.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The cutting insert according to this disclosure comprises a top surface, a bottom surface, and an outer peripheral surface. The bottom surface is opposite the top surface. The outer peripheral surface is connected to both the top surface and the bottom surface. The ridge between the top surface and the outer peripheral surface includes a first cutting edge, a corner cutting edge, and a second cutting edge. The corner cutting edge is connected to the first cutting edge. The second cutting edge is connected to the corner cutting edge. The second cutting edge is opposite the first cutting edge relative to the corner cutting edge. A projection is provided on the top surface. Viewed in a first direction perpendicular to the bottom surface and from the top surface toward the bottom surface, the projection extends along the angle bisector of the angle between the first cutting edge and the second cutting edge. In a cross section perpendicular to the angle bisector, the projection is curved and convex outward. In the first direction, the projection is located closer to the bottom surface than each of the first and second cutting edges. Viewed in the first direction, the intersection of the corner cutting edge and the bisector is defined as the reference point. In a first cross-section perpendicular to the bisector and at a distance of 0.5 mm from the reference point, the distance between the first cutting edge and the projection in the first direction is defined as the first distance, and the distance between the second cutting edge and the projection in the first direction is defined as the second distance. In a second cross-section perpendicular to the bisector and at a distance of 1.5 mm from the reference point, the distance between the first cutting edge and the projection in the first direction is defined as the third distance, and the distance between the second cutting edge and the projection in the first direction is defined as the fourth distance. The third distance is greater than the first distance. The fourth distance is greater than the second distance. The ratio of the height of the projection to the width of the projection in the second cross-section is smaller than the ratio of the height of the projection to the width of the projection in the first cross-section. [Brief explanation of the drawing]

[0005] [Figure 1] Figure 1 is a schematic perspective view showing the configuration of a cutting insert according to the first embodiment. [Figure 2] Figure 2 is a schematic side view showing the configuration of a cutting insert according to the first embodiment. [Figure 3] Figure 3 is a schematic plan view showing the configuration of a cutting insert according to the first embodiment. [Figure 4] Figure 4 is an enlarged schematic diagram showing region IV in Figure 3. [Figure 5] Figure 5 is a schematic longitudinal section along the VV line in Figure 4. [Figure 6] Figure 6 is a schematic longitudinal section along the line VI-VI in Figure 4. [Figure 7] Figure 7 is a schematic longitudinal section along the line VII-VII in Figure 4. [Figure 8] Figure 8 is a schematic longitudinal section along the line VIII-VIII in Figure 4. [Figure 9] Figure 9 is a schematic plan view showing the configuration of a cutting insert according to the second embodiment. [Figure 10] Figure 10 is an enlarged schematic diagram showing region X in Figure 9. [Figure 11] Figure 11 is a schematic longitudinal section along the line XI-XI in Figure 10. [Figure 12] Figure 12 is a schematic longitudinal section along the line XII-XII in Figure 10. [Figure 13] Figure 13 is a schematic longitudinal section along the line XIII-XIII in Figure 10. [Figure 14] Figure 14 is a schematic plan view showing the configuration of a cutting insert according to the third embodiment. [Figure 15] Figure 15 is an enlarged schematic diagram showing region XV in Figure 14. [Figure 16] Figure 16 is a schematic longitudinal section along the line XVI-XVI in Figure 15. [Figure 17] Figure 17 is a schematic longitudinal section along the line XVII-XVII in Figure 15. [Figure 18] Figure 18 is a schematic longitudinal section along the line XVIII-XVIII in Figure 15. [Figure 19] Figure 19 is a schematic diagram showing the process of cutting a workpiece using a cutting insert. [Modes for carrying out the invention]

[0006] [Issues this disclosure aims to address] The purpose of this disclosure is to provide a cutting insert that can improve chip handling when the depth of cut is small and reduce cutting resistance when the depth of cut is large.

[0007] [Effects of this disclosure] According to this disclosure, it is possible to provide a cutting insert that can improve chip handling when the depth of cut is small and reduce cutting resistance when the depth of cut is large.

[0008] [Summary of the Embodiment] First, an overview of the embodiments of this disclosure will be described.

[0009] (1) The cutting insert 100 according to the present disclosure comprises a top surface 1, a bottom surface 2, and an outer peripheral surface 8. The bottom surface 2 is opposite to the top surface 1. The outer peripheral surface 8 is connected to both the top surface 1 and the bottom surface 2. The ridge line 20 between the top surface 1 and the outer peripheral surface 8 includes a first cutting edge 11, a corner cutting edge 13, and a second cutting edge 12. The corner cutting edge 13 is connected to the first cutting edge 11. The second cutting edge 12 is connected to the corner cutting edge 13. The second cutting edge 12 is opposite to the first cutting edge 11 with respect to the corner cutting edge 13. A projection 4 is provided on the top surface 1. Viewed in a first direction 101 from the top surface 1 toward the bottom surface 2 and perpendicular to the bottom surface 2, the projection 4 extends along the angle bisector 99 of the angle between the first cutting edge 11 and the second cutting edge 12. In a cross section perpendicular to the bisector 99, the projection 4 is curved and convex outward. In the first direction 101, the projection 4 is positioned closer to the bottom surface 2 than the first cutting edge 11 and the second cutting edge 12. In the first direction 101, the intersection of the corner cutting edge 13 and the bisector 99 is defined as the reference point 98. In the first cross section CS1, which is 0.5 mm from the reference point 98 and perpendicular to the bisector 99, the distance between the first cutting edge 11 and the projection 4 in the first direction 101 is defined as the first distance D1, and the distance between the second cutting edge 12 and the projection 4 in the first direction 101 is defined as the second distance D2. In a second cross section CS2 that is 1.5 mm from the reference point 98 and perpendicular to the line bisector 99, the distance between the first cutting edge 11 and the projection 4 in the first direction 101 is the third distance D3, and the distance between the second cutting edge 12 and the projection 4 in the first direction 101 is the fourth distance D4. The third distance D3 is greater than the first distance D1. The fourth distance D4 is greater than the second distance D2. The ratio of the height of the projection 4 (fourth height H4) to the width of the projection 4 (fourth width W4) in the second cross section CS2 is smaller than the ratio of the height of the projection 4 (third height H3) to the width of the projection 4 (third width W3) in the first cross section CS1.

[0010] (2) According to the cutting insert 100 according to (1) above, the top surface 1 may have a first rake face 31 and a second rake face 32. The first rake face 31 may be continuous with the first cutting edge 11. The first rake face 31 may be between the first cutting edge 11 and the protrusion 4. The second rake face 32 may be continuous with the second cutting edge 12. The second rake face 32 may be between the second cutting edge 12 and the protrusion 4. The ratio of the height of the first rake face 31 to the width of the first rake face 31 in the second cross-section CS2 may be smaller than the ratio of the height (first height H1) of the first rake face 31 to the width (first width W1) of the first rake face 31 in the first cross-section CS1. The ratio of the height of the second rake face 32 to the width of the second rake face 32 in the second cross-section CS2 may be smaller than the ratio of the height (second height H2) of the second rake face 32 to the width (second width W2) of the second rake face 32 in the first cross-section CS1. In the first cross-section CS1, each of the first rake face 31 and the second rake face 32 may be a convex curved shape on the outside. In the first cross-section CS1, the rake angle (first rake angle θ11) of the first rake face 31 may increase as it approaches the protrusion 4 from the first cutting edge 11. In the first cross-section CS1, the rake angle (second rake angle θ12) of the second rake face 32 may increase as it approaches the protrusion 4 from the second cutting edge 12.

[0011] (3) According to the cutting insert 100 according to (2) above, in the second cross-section CS2, each of the first rake face 31 and the second rake face 32 may be linear.

[0012] (4) According to the cutting insert 100 according to (2) or (3) above, the top surface 1 may further have a third rake face 33 and a corner rake face 34. The third rake face 33 may be between the first rake face 31 and the second rake face 32. The third rake face 33 may be constituted by the protrusion 4. The corner rake face 34 may be between the third rake face 33 and the corner cutting edge 13. The third rake face 33 may have a first surface 41 and a second surface 42. The first surface 41 may be opposite to the corner rake face 34 with respect to the corner cutting edge 13. The second surface 42 may be continuous with the first surface 41. The second surface 42 may be opposite to the first surface 41 with respect to the corner rake face 34. In a cross-section (fourth cross-section CS4) parallel to the first direction 101 and including the bisector 99, the first surface 41 may be inclined with respect to the corner rake face 34 in the second direction 102 from the bottom surface 2 toward the top surface 1. In a cross-section (fourth cross-section CS4) parallel to the first direction 101 and including the bisector 99, the second surface 42 may be closer to the bottom surface 2 than the first surface 41.

[0013] [Details of Embodiment] Hereinafter, details of the embodiments of the present disclosure will be described. In the following description, the same or corresponding elements are denoted by the same reference numerals, and the same description thereof will not be repeated.

[0014] (First Embodiment) First, the configuration of the cutting insert 100 according to the first embodiment will be described.

[0015] FIG. 1 is a perspective schematic view showing the configuration of the cutting insert 100 according to the first embodiment. As shown in FIG. 1, the cutting insert 100 mainly has a top surface 1, a bottom surface 2, an inner peripheral surface 7, and an outer peripheral surface 8. The bottom surface 2 is opposite to the top surface 1. The inner peripheral surface 7 is continuous with each of the top surface 1 and the bottom surface 2. The inner peripheral surface 7 forms a through-hole 9. The through-hole 9 penetrates the top surface 1 and the bottom surface 2. The outer peripheral surface 8 is continuous with each of the top surface 1 and the bottom surface 2. The outer peripheral surface 8 is outside the inner peripheral surface 7.

[0016] At least a portion of the ridge line 20 between the top surface 1 and the outer peripheral surface 8 functions as a cutting edge. The ridge line 20 is annular. The ridge line 20 has a pair of cutting edge portions 10, a pair of first straight portions 14, and a pair of second straight portions 15. In the ridge line 20, the cutting edge portions 10, the first straight portions 14, and the second straight portions 15 are alternately located in the circumferential direction. In this specification, the circumferential direction refers to the circumferential direction of the ridge line 20. Each of the pair of cutting edge portions 10 is opposite to the through hole 9. In other words, the through hole 9 is between the pair of cutting edge portions 10. Each of the pair of first straight portions 14 is opposite to the through hole 9. In other words, the through hole 9 is between the pair of first straight portions 14. Each of the pair of second straight portions 15 is opposite to the through hole 9. In other words, the through hole 9 is between the pair of second straight portions 15.

[0017] The cutting edge section 10 has a first cutting edge 11, a corner cutting edge 13, and a second cutting edge 12. The first cutting edge 11 is connected to the first straight section 14. The corner cutting edge 13 is connected to the first cutting edge 11. The corner cutting edge 13 is opposite the first straight section 14 to the first cutting edge 11. From another point of view, in the circumferential direction, the first cutting edge 11 is located between the first straight section 14 and the corner cutting edge 13. The second cutting edge 12 is connected to the corner cutting edge 13. The second cutting edge 12 is opposite the first cutting edge 11 to the corner cutting edge 13. From another point of view, in the circumferential direction, the corner cutting edge 13 is located between the first cutting edge 11 and the second cutting edge 12. The second straight section 15 is connected to the second cutting edge 12. The second straight section 15 is located opposite the corner cutting edge 13 to the second cutting edge 12. From another perspective, in the circumferential direction, the second cutting edge 12 is located between the corner cutting edge 13 and the second straight section 15.

[0018] The top surface 1 has a first rake face 31, a second rake face 32, a third rake face 33, a rising surface 6, and a flat surface 5. The first rake face 31 is connected to the first cutting edge 11. The second rake face 32 is connected to the second cutting edge 12. The third rake face 33 is located between the first rake face 31 and the second rake face 32. From another perspective, the first rake face 31 is located between the first cutting edge 11 and the third rake face 33. The second rake face 32 is located between the second cutting edge 12 and the third rake face 33.

[0019] The rising surface 6 is spaced apart from the ridge line 20. The flat surface 5 is located between the rising surface 6 and the inner circumferential surface 7. The rising surface 6 rises toward the flat surface 5 from each of the first rake face 31, the second rake face 32, and the third rake face 33.

[0020] A projection 4 is provided on the top surface 1. The third rake face 33 is formed by the projection 4. In other words, the projection 4 is located between the first rake face 31 and the second rake face 32. From another perspective, the first rake face 31 is located between the first cutting edge 11 and the projection 4. The second rake face 32 is located between the second cutting edge 12 and the projection 4. The projection 4 is located between the corner cutting edge 13 and the rising surface 6.

[0021] Figure 2 is a schematic side view showing the configuration of a cutting insert 100 according to the first embodiment. As shown in Figure 2, the bottom surface 2 may be planar. In this specification, the direction from the top surface 1 to the bottom surface 2 is referred to as the first direction 101. The first direction 101 is perpendicular to the bottom surface 2. The flat surface 5 of the top surface 1 may be planar. The flat surface 5 is substantially parallel to the bottom surface 2. The first cutting edge 11 is concave in the first direction 101. In other words, the first cutting edge 11 is a curved shape that is convex in the first direction 101. The second cutting edge 12 is concave in the first direction 101. In other words, the second cutting edge 12 is a curved shape that is convex in the first direction 101. The first straight section 14 is substantially parallel to the bottom surface 2. The second straight section 15 is substantially parallel to the bottom surface 2. In the first direction 101, the ridge line 20 is located between the bottom surface 2 and the flat surface 5.

[0022] Figure 3 is a schematic plan view showing the configuration of the cutting insert 100 according to the first embodiment. As shown in Figure 3, when viewed in the first direction 101 (see Figure 2), the center of the inner circumferential surface 7 is defined as center O. When viewed in the first direction 101, the line that bisects the angle between the first cutting edge 11 and the second cutting edge 12 is defined as the bisector 99. When viewed in the first direction 101, the bisector 99 passes through center O.

[0023] As shown in Figure 3, when viewed in the first direction 101, the ridge line 20 is approximately a parallelogram. When viewed in the first direction 101, each of the pair of first straight sections 14 may be substantially parallel to each other. Each of the pair of second straight sections 15 may be substantially parallel to each other.

[0024] As shown in Figure 3, when viewed in the first direction 101, the first cutting edge 11 and the second cutting edge 12 Na The angle is acute. When viewed in the first direction 101, the angle between the first straight section 14 and the second straight section 15 is obtuse. When viewed in the first direction 101, the angle between the first straight section 14 and the second straight section 15 is called the first angle θ1. The first angle θ1 is, for example, 125°. The first angle θ1 may also be, for example, 120° or more and 130° or less.

[0025] As shown in Figure 3, the shape of the vertex 1 is substantially symmetric with respect to the angle bisector 99 when viewed in the first direction 101. From another point of view, the shape of the ridge 20 is substantially symmetric with respect to the angle bisector 99 when viewed in the first direction 101. The shape of the vertex 1 is substantially twofold symmetric with respect to the center O when viewed in the first direction 101. From another point of view, the shape of the ridge 20 is substantially twofold symmetric with respect to the center O when viewed in the first direction 101.

[0026] Viewed in the first direction 101, the projection 4 extends along the bisector 99. Viewed in the first direction 101, the bisector 99 lies between the first rake face 31 and the second rake face 32. Viewed in the first direction 101, the bisector 99 intersects each of the pair of corner cutting edges 13.

[0027] Figure 4 is an enlarged schematic diagram showing region IV of Figure 3. As shown in Figure 4, one end of the corner cutting edge 13 is the first end 91. The end of the corner cutting edge 13 opposite to the first end 91 is the second end 92. At the first end 91, the corner cutting edge 13 is connected to the first cutting edge 11. At the second end 92, the corner cutting edge 13 is connected to the second cutting edge 12. Viewed in the first direction 101, the intersection point of the corner cutting edge 13 and the bisector 99 is the reference point 98. Viewed in the first direction 101, the first cutting edge 11 and the second cutting edge 12 are each straight lines. Viewed in the first direction 101, the corner cutting edge 13 is arc-shaped.

[0028] As shown in Figure 4, when viewed in the first direction 101, the second cutting edge 12 is inclined with respect to the first cutting edge 11. The angle between the first cutting edge 11 and the second cutting edge 12 when viewed in the first direction 101 is called the second angle θ2. The second angle θ2 is, for example, 55°. The second angle θ2 may also be, for example, between 50° and 60°.

[0029] As shown in Figure 4, the top surface 1 further has a corner rake face 34, a first intermediate rake face 21, and a second intermediate rake face 22. The corner rake face 34 is located between the third rake face 33 and the corner cutting edge 13. The corner rake face 34 is connected to the corner cutting edge 13, the first rake face 31, the second rake face 32, and the third rake face 33, respectively.

[0030] The first intermediate rake face 21 is located between the first rake face 31 and the third rake face 33. The first intermediate rake face 21 is connected to each of the first rake face 31, the third rake face 33, and the corner rake face 34.

[0031] The second intermediate rake face 22 is located between the second rake face 32 and the third rake face 33. The second intermediate rake face 22 is connected to each of the second rake face 32, the third rake face 33, and the corner rake face 34. The second intermediate rake face 22 is opposite the first intermediate rake face 21 to the third rake face 33. From another perspective, the third rake face 33 is located between the first intermediate rake face 21 and the second intermediate rake face 22.

[0032] The corner rake face 34 is composed of a first corner rake section 71 and a second corner rake section 72. The first corner rake section 71 is connected to the corner cutting edge 13, the first rake face 31, and the second rake face 32, respectively.

[0033] The second corner rake section 72 is located opposite the corner cutting edge 13 to the first corner rake section 71. From another perspective, the first corner rake section 71 is located between the corner cutting edge 13 and the second corner rake section 72. The second corner rake section 72 is located between the first corner rake section 71 and the third rake face 33. The second corner rake section 72 is connected to each of the first corner rake section 71, the first intermediate rake face 21, the second intermediate rake face 22, and the third rake face 33.

[0034] The first rake face 31 is composed of a first rake portion 61 and a second rake portion 62. The first rake portion 61 is connected to the first cutting edge 11, the first corner rake portion 71, and the first intermediate rake face 21, respectively.

[0035] The second rake section 62 is located opposite the first corner rake section 71 to the first rake section 61. From another perspective, the first rake section 61 is located between the first corner rake section 71 and the second rake section 62. The second rake section 62 is connected to the first cutting edge 11, the first rake section 61, and the first intermediate rake face 21, respectively.

[0036] The second rake face 32 is composed of a third rake portion 63 and a fourth rake portion 64. The third rake portion 63 is connected to the second cutting edge 12, the first corner rake portion 71, and the second intermediate rake face 22, respectively. The fourth rake portion 64 is opposite the first corner rake portion 71 to the third rake portion 63. From another perspective, the third rake portion 63 is located between the first corner rake portion 71 and the fourth rake portion 64. The fourth rake portion 64 is connected to the second cutting edge 12, the third rake portion 63, and the second intermediate rake face 22, respectively.

[0037] The third rake face 33 has a first face 41 and a second face 42. The first face 41 is opposite the corner cutting edge 13 to the corner rake face 34. From another perspective, the corner rake face 34 is between the corner cutting edge 13 and the first face 41. The first face 41 is continuous with the corner rake face 34, the first intermediate rake face 21 and the second intermediate rake face 22, respectively. Viewed in the first direction 101, the first face 41 extends along the bisector 99. Viewed in the first direction 101, the width of the first face 41 in the direction perpendicular to the bisector 99 may increase as it moves away from the reference point 98.

[0038] The second face 42 is opposite the corner rake face 34 to the first face 41. From another perspective, the first face 41 is between the corner rake face 34 and the second face 42. The second face 42 is connected to the first face 41, the first intermediate rake face 21, and the second intermediate rake face 22, respectively. Viewed in the first direction 101, the second face 42 extends along the bisector 99.

[0039] The second surface 42 is composed of a first part 51, a second part 52, and a third part 53. The first part 51 is opposite the corner rake face 34 to the first surface 41. In other words, the first surface 41 is between the corner rake face 34 and the first part 51. The first part 51 is connected to the first surface 41, the first intermediate rake face 21, and the second intermediate rake face 22, respectively. Viewed in the first direction 101, the first part 51 extends along the bisector 99. Viewed in the first direction 101, the width of the first part 51 in the direction perpendicular to the bisector 99 may be substantially the same across the entire surface of the first part 51.

[0040] The second part 52 is opposite the first face 41 to the first part 51. From another perspective, the first part 51 is between the first face 41 and the second part 52. The second part 52 is connected to the first part 51, the first intermediate rake face 21, and the second intermediate rake face 22, respectively. Viewed in the first direction 101, the second part 52 extends along the bisector 99. Viewed in the first direction 101, the width of the second part 52 in the direction perpendicular to the bisector 99 may increase as it moves away from the reference point 98.

[0041] The third part 53 is opposite the first part 51 to the second part 52. From another perspective, the second part 52 is between the first part 51 and the third part 53. The third part 53 is connected to the second part 52 and to the first intermediate rake face 21 and the second intermediate rake face 22, respectively. Viewed in the first direction 101, the third part 53 extends along the bisector 99. Viewed in the first direction 101, the width of the third part 53 in the direction perpendicular to the bisector 99 may decrease as it moves away from the reference point 98.

[0042] Figure 5 is a schematic longitudinal section along the VV line in Figure 4. The section shown in Figure 5 is 0.5 mm from the reference point 98 and is perpendicular to the line bisector 99. The section shown in Figure 5 is referred to as the first section CS1.

[0043] In a cross section perpendicular to the bisector 99, the line passing through both ends of the first rake face 31 is defined as the first virtual line 111. In a cross section perpendicular to the bisector 99, the line passing through both ends of the second rake face 32 is defined as the second virtual line 112. In a cross section perpendicular to the bisector 99, the line passing through both ends of the projection 4 is defined as the third virtual line 113.

[0044] In this specification, the distance between the ends of a surface in a cross section perpendicular to the bisector 99 is defined as the width of the surface. Specifically, for example, the distance between the ends of the first rake face 31 in a cross section perpendicular to the bisector 99 is defined as the width of the first rake face 31. The distance between the ends of a projection 4 in a cross section perpendicular to the bisector 99 is defined as the width of the projection 4.

[0045] In this specification, the maximum distance between a plane and a line passing through both ends of the plane in a cross section perpendicular to the bisector 99 is defined as the height of the plane. Specifically, the distance between the point on the first rake face 31 that is furthest from the first virtual line 111 in a cross section perpendicular to the bisector 99 and the first virtual line 111 is defined as the height of the first rake face 31. In a cross section perpendicular to the bisector 99, the distance between the point on the projection 4 that is furthest from the third virtual line 113 and the third virtual line 113 is defined as the height of the projection 4.

[0046] A line parallel to the base 2 (see Figure 2) and perpendicular to the angle bisector 99 (see Figure 4) is defined as the fourth virtual line 114. In a cross section perpendicular to the angle bisector 99, the angle between the fourth virtual line 114 and the first rake face 31 is defined as the first rake angle θ11. Specifically, the first rake angle θ11 is the angle between the fourth virtual line 114 and the tangent to the first rake face 31. In other words, the first rake angle θ11 is the rake angle of the first rake face 31.

[0047] In a cross section perpendicular to the angle bisector 99, the angle between the fourth virtual line 114 and the second rake plane 32 is defined as the second rake angle θ12. Specifically, the second rake angle θ12 is the angle between the fourth virtual line 114 and the tangent to the second rake plane 32. In other words, the second rake angle θ12 is the rake angle of the second rake plane 32.

[0048] As shown in Figure 5, in the first cross section CS1, the first rake face 31 smoothly connects to the first intermediate rake face 21 at the first connection point 121. From another perspective, in the first cross section CS1, the inclination of the tangent to the first rake face 31 and the inclination of the tangent to the first intermediate rake face 21 change continuously at the first connection point 121. In the first cross section CS1, the first intermediate rake face 21 smoothly connects to the projection 4 at the second connection point 122. From another perspective, in the first cross section CS1, the inclination of the tangent to the first intermediate rake face 21 and the inclination of the tangent to the projection 4 change continuously at the second connection point 122.

[0049] The projection 4 smoothly connects to the second intermediate rake face 22 at the third connection point 123. From another perspective, in the first cross section CS1, the inclination of the tangent to the projection 4 and the inclination of the tangent to the second intermediate rake face 22 change continuously at the third connection point 123. The second intermediate rake face 22 smoothly connects to the second rake face 32 at the fourth connection point 124. From another perspective, in the first cross section CS1, the inclination of the tangent to the second intermediate rake face 22 and the inclination of the tangent to the second rake face 32 change continuously at the fourth connection point 124. The first connection point 121, the second connection point 122, the third connection point 123, and the fourth connection point 124 are each inflection points.

[0050] As shown in Figure 5, in the first cross section CS1, the first virtual line 111 passes through the point of contact between the first rake face 31 and the first cutting edge 11 and the first connection point 121, respectively. In the first cross section CS1, the second virtual line 112 passes through the point of contact between the second rake face 32 and the second cutting edge 12 and the fourth connection point 124, respectively. In the first cross section CS1, the third virtual line 113 passes through the second connection point 122 and the third connection point 123, respectively.

[0051] As shown in Figure 5, in the first cross section CS1, each of the first rake portion 61 and the third rake portion 63 is curved and convex outward. In other words, in the first cross section CS1, each of the first rake face 31 and the second rake face 32 is curved and convex outward. In the first cross section CS1, each of the first rake portion 61 and the third rake portion 63 may be substantially arc-shaped and convex outward. In other words, in the first cross section CS1, each of the first rake face 31 and the second rake face 32 may be substantially arc-shaped and convex outward.

[0052] The radius of curvature of the first rake face 31 in the first cross section CS1 is defined as the first radius of curvature R1. The first radius of curvature R1 is, for example, 0.65 mm. The first radius of curvature R1 may also be, for example, between 0.30 mm and 2.00 mm.

[0053] The radius of curvature of the second rake face 32 in the first cross section CS1 is defined as the second radius of curvature R2. The second radius of curvature R2 may be substantially equal to the first radius of curvature R1. The second radius of curvature R2 is, for example, 0.65 mm. The second radius of curvature R2 may also be, for example, between 0.30 mm and 2.00 mm.

[0054] The width of the first rake face 31 in the first section CS1 is defined as the first width W1. In other words, the first width W1 is the distance between the point of contact between the first rake face 31 and the first cutting edge 11 in the first section CS1 and the first connection point 121. The height of the first rake face 31 in the first section CS1 is defined as the first height H1. The ratio of the first height H1 to the first width W1 is defined as the first ratio. The first ratio is, for example, 0.036. The first ratio may be, for example, 0.005 or more and 0.100 or less. The lower limit of the first ratio is not particularly limited, but may be, for example, 0.010 or more, or 0.020 or more. The upper limit of the first ratio is not particularly limited, but may be, for example, 0.080 or less, or 0.060 or less.

[0055] The width of the second rake face 32 in the first section CS1 is defined as the second width W2. In other words, the second width W2 is the distance between the point of contact between the second rake face 32 and the second cutting edge 12 in the first section CS1 and the fourth connection point 124. The height of the second rake face 32 in the first section CS1 is defined as the second height H2. The ratio of the second height H2 to the second width W2 is defined as the second ratio. The second ratio may be substantially equal to the first ratio. The second ratio is, for example, 0.036. The second ratio may be, for example, between 0.005 and 0.100. The lower limit of the second ratio is not particularly limited, but may be, for example, 0.010 or more, or 0.020 or more. The upper limit of the second ratio is not particularly limited, but may be, for example, 0.080 or less, or 0.060 or less.

[0056] In the first cross section CS1, the first rake angle θ11 increases as it approaches the projection 4 from the first cutting edge 11. In the first cross section CS1, the first rake angle θ11 at the point of contact between the first rake face 31 and the first cutting edge 11 is, for example, 12°. In the first cross section CS1, the first rake angle θ11 at the point of contact between the first rake face 31 and the first cutting edge 11 may be, for example, 10° or more and 20° or less. In the first cross section CS1, the first rake angle θ11 at the first connection point 121 is, for example, 28°. In the first cross section CS1, the first rake angle θ11 at the first connection point 121 may be, for example, 20° or more and 40° or less.

[0057] In the first cross-section CS1, the second rake angle θ12 increases as it approaches the projection 4 from the second cutting edge 12. In the first cross-section CS1, the second rake angle θ12 at the point of contact between the second rake face 32 and the second cutting edge 12 is, for example, 12°. In the first cross-section CS1, the second rake angle θ12 at the point of contact between the second rake face 32 and the second cutting edge 12 may be, for example, 10° or more and 20° or less. In the first cross-section CS1, the second rake angle θ12 at the fourth connection point 124 is, for example, 28°. In the first cross-section CS1, the second rake angle θ12 at the fourth connection point 124 may be, for example, 20° or more and 40° or less.

[0058] As shown in Figure 5, in the first cross-section CS1, the projection 4 is a curved shape that is convex outward. In the first cross-section CS1, the projection 4 may also be a substantially convex arc shape that is convex outward. The radius of curvature of the projection 4 in the first cross-section CS1 is the third radius of curvature R3. The third radius of curvature R3 is, for example, 0.16 mm. The third radius of curvature R3 may also be, for example, 0.10 mm or more and 0.30 mm or less.

[0059] The width of the projection 4 in the first cross-section CS1 is defined as the third width W3. Specifically, the third width W3 is the distance between the second connection point 122 and the third connection point 123. The third width W3 is, for example, 0.1 mm. The third width W3 may also be, for example, 0.05 mm or more and 0.15 mm or less.

[0060] The height of the projection 4 in the first cross-section CS1 is defined as the third height H3. The ratio of the third height H3 to the third width W3 is defined as the third ratio. The third ratio is, for example, 0.084. The third ratio may also be, for example, between 0.030 and 0.140. The lower limit of the third ratio is not particularly limited, but may be, for example, 0.045 or more, or 0.060 or more. The upper limit of the third ratio is not particularly limited, but may be, for example, 0.120 or less, or 0.100 or less.

[0061] As shown in Figure 5, the projection 4 is provided at a position close to the bottom surface 2 (see Figure 2) with respect to each of the first cutting edge 11 and the second cutting edge 12. In the first cross section CS1, the distance between the first cutting edge 11 and the projection 4 in the first direction 101 is defined as the first distance D1. The first distance D1 is, for example, 0.070 mm. The first distance D1 may be, for example, 0.020 mm or more and 0.140 mm or less. The lower limit of the first distance D1 is not particularly limited, but may be, for example, 0.035 mm or more or 0.050 mm or more. The upper limit of the first distance D1 is not particularly limited, but may be, for example, 0.120 mm or less or 0.100 mm or less.

[0062] In the first cross section CS1, the distance between the second cutting edge 12 and the projection 4 in the first direction 101 is defined as the second distance D2. The first distance D1 and the second distance D2 may be substantially equal. The second distance D2 is, for example, 0.070 mm. The second distance D2 may be, for example, 0.020 mm or more and 0.140 mm or less. The lower limit of the second distance D2 is not particularly limited, but may be, for example, 0.035 mm or more, or 0.050 mm or more. The upper limit of the second distance D2 is not particularly limited, but may be, for example, 0.120 mm or less, or 0.100 mm or less.

[0063] As shown in Figure 5, in the first cross section CS1, the first intermediate rake face 21 is concave. In other words, in the first cross section CS1, the first intermediate rake face 21 is curved and convex inward. In the first cross section CS1, the width of the first intermediate rake face 21 may be greater than the third width W3. In other words, in the first cross section CS1, the distance between the first connection point 121 and the second connection point 122 may be greater than the third width W3.

[0064] As shown in Figure 5, in the first cross section CS1, the second intermediate rake face 22 is concave. In other words, in the first cross section CS1, the second intermediate rake face 22 is curved and convex inward. In the first cross section CS1, the width of the second intermediate rake face 22 may be greater than the third width W3. In other words, in the first cross section CS1, the distance between the third connection point 123 and the fourth connection point 124 may be greater than the third width W3.

[0065] As shown in Figure 5, the corner cutting edge 13 may be straight when viewed in the direction along the bisector 99. The corner cutting edge 13 may also be parallel to the bottom surface 2 (see Figure 2) when viewed in the direction along the bisector 99.

[0066] Figure 6 is a schematic longitudinal section along the line VI-VI in Figure 4. The section shown in Figure 6 is 1.5 mm from the reference point 98 and is perpendicular to the line bisector 99. The section shown in Figure 6 is referred to as the second section CS2.

[0067] As shown in Figure 6, in the second cross section CS2, the second rake portion 62 of the first rake face 31 and the fourth rake portion 64 of the second rake face 32 are both straight. In other words, in the second cross section CS2, the first rake face 31 and the second rake face 32 are both straight. From another point of view, in the second cross section CS2, the radius of curvature of the first rake face 31 and the second rake face 32 is infinite.

[0068] In the second cross section CS2, the ratio of the height of the first rake face 31 to the width of the first rake face 31 is smaller than the first ratio. Specifically, in the second cross section CS2, the height of the first rake face 31 is 0 mm. In the second cross section CS2, the ratio of the height of the first rake face 31 to the width of the first rake face 31 is 0.

[0069] The ratio of the height of the second rake face 32 to the width of the second rake face 32 in the second cross section CS2 is smaller than the second ratio. Specifically, in the second cross section CS2, the height of the second rake face 32 is 0 mm. The ratio of the height of the second rake face 32 to the width of the second rake face 32 in the second cross section CS2 is 0.

[0070] In the second cross-section CS2, the first rake angle θ11 is substantially the same across the entire surface of the first rake face 31. In the second cross-section CS2, the first rake angle θ11 is, for example, 20°. In the second cross-section CS2, the first rake angle θ11 may be, for example, 15° or more and 25° or less.

[0071] In the second cross-section CS2, the second rake angle θ12 is substantially the same across the entire surface of the second rake face 32. In the second cross-section CS2, the second rake angle θ12 is, for example, 20°. In the second cross-section CS2, the second rake angle θ12 may be, for example, 15° or more and 25° or less.

[0072] In the second cross-section CS2, the distance between the first cutting edge 11 and the projection 4 in the first direction 101 is defined as the third distance D3. The third distance D3 is greater than the first distance D1. The third distance D3 is, for example, 0.11 mm. The third distance D3 may also be, for example, 0.04 mm or more and 0.20 mm or less. The lower limit of the third distance D3 is not particularly limited, but may be, for example, 0.06 mm or more, or 0.08 mm or more. The upper limit of the third distance D3 is not particularly limited, but may be, for example, 0.18 mm or less, or 0.15 mm or less.

[0073] In the second cross section CS2, the distance between the second cutting edge 12 and the projection 4 in the first direction 101 is defined as the fourth distance D4. The fourth distance D4 is greater than the second distance D2. The fourth distance D4 may be substantially equal to the third distance D3. The fourth distance D4 is, for example, 0.11 mm. The fourth distance D4 may be, for example, 0.04 mm or more and 0.20 mm or less. The lower limit of the fourth distance D4 is not particularly limited, but may be, for example, 0.06 mm or more, or 0.08 mm or more. The upper limit of the fourth distance D4 is not particularly limited, but may be, for example, 0.18 mm or less, or 0.15 mm or less.

[0074] As shown in Figure 6, in the second cross-section CS2, the projection 4 is a curved shape that is convex outward. In the second cross-section CS2, the projection 4 may also be substantially an arc shape that is convex outward. The radius of curvature of the projection 4 in the second cross-section CS2 is the fourth radius of curvature R4. The fourth radius of curvature R4 is greater than the third radius of curvature R3. The fourth radius of curvature R4 is, for example, 0.9 mm. The fourth radius of curvature R4 may also be, for example, between 0.5 mm and 4.0 mm.

[0075] The width of the projection 4 in the second cross-section CS2 is defined as the fourth width W4. The fourth width W4 is greater than the third width W3. The fourth width W4 is, for example, 0.45 mm. The fourth width W4 may also be, for example, between 0.20 mm and 0.80 mm. The ratio of the third width W3 to the fourth width W4 is, for example, 0.22. The ratio of the third width W3 to the fourth width W4 may also be, for example, between 0.10 and 0.50.

[0076] The height of the projection 4 in the second cross-section CS2 is defined as the fourth height H4. The ratio of the fourth height H4 to the fourth width W4 is defined as the fourth ratio. The fourth ratio is smaller than the third ratio. The fourth ratio is, for example, 0.064. The fourth ratio may also be, for example, between 0.005 and 0.130. The lower limit of the fourth ratio is not particularly limited, but may be, for example, 0.015 or more, or 0.030 or more. The upper limit of the fourth ratio is not particularly limited, but may be, for example, 0.110 or less, or 0.09 or less.

[0077] As shown in Figure 6, in the second section CS2, the width of the first intermediate rake face 21 may be smaller than the fourth width W4. In the second section CS2, the width of the second intermediate rake face 22 may be smaller than the fourth width W4.

[0078] Figure 7 is a schematic longitudinal section along the line VII-VII in Figure 4. The section shown in Figure 7 is 0.25 mm from the reference point 98 and is perpendicular to the line bisector 99. The section shown in Figure 7 is designated as the third section CS3.

[0079] As shown in Figure 7, the third cross section CS3 does not intersect with the projection 4 (see Figure 4). From another point of view, the distance between the projection 4 and the reference point 98 (see Figure 4) is 0.25 mm or more. In the third cross section CS3, the first rake face 31 and the second rake face 32 are connected by an inwardly convex curve. In the third cross section CS3, the second corner rake portion 72 is concave. In other words, in the third cross section CS3, the second corner rake portion 72 is an inwardly convex curve.

[0080] Figure 8 is a schematic longitudinal section along the line VIII-VIII in Figure 4. The section shown in Figure 8 is parallel to the first direction 101 and includes the line bisector 99. The section shown in Figure 8 is designated as the fourth section CS4. As shown in Figure 8, the first corner bevel 71 smoothly connects to the second corner bevel 72 at the fifth connection point 125. From another perspective, in the fourth section CS4, the inclination of the tangent to the first corner bevel 71 and the inclination of the tangent to the second corner bevel 72 change continuously at the fifth connection point 125. The second corner bevel 72 smoothly connects to the first surface 41 of the third bevel surface 33 at the sixth connection point 126. From another perspective, in the fourth section CS4, the inclination of the tangent to the second corner scuff 72 and the inclination of the tangent to the first surface 41 change continuously at the sixth connection point 126.

[0081] The first surface 41 smoothly connects to the first part 51 of the second surface 42 at the seventh connection point 127. From another perspective, in the fourth section CS4, the inclination of the tangent to the first surface 41 and the inclination of the tangent to the first part 51 change continuously at the seventh connection point 127. The first part 51 smoothly connects to the second part 52 at the eighth connection point 128. From another perspective, in the fourth section CS4, the inclination of the tangent to the first part 51 and the inclination of the tangent to the second part 52 change continuously at the eighth connection point 128. The fifth connection point 125, the sixth connection point 126, the seventh connection point 127, and the eighth connection point 128 may each be inflection points.

[0082] As shown in Figure 8, in the fourth section CS4, the first corner bevel 71 is curved and convex outward. In the fourth section CS4, the second corner bevel 72 is concave. In other words, in the fourth section CS4, the second corner bevel 72 is curved and convex inward. In the fourth section CS4, the first surface 41 may be straight. In the fourth section CS4, the first surface 41 may be substantially parallel to the bottom surface 2 (see Figure 2).

[0083] As shown in Figure 8, in the fourth cross-section CS4, the first portion 51 may be curved. In the fourth cross-section CS4, the first portion 51 may have an outwardly convex curved portion and an inwardly convex curved portion. In other words, in the fourth cross-section CS4, the first portion 51 may have an inflection point. In the fourth cross-section CS4, the second portion 52 may be an outwardly convex curved portion.

[0084] As shown in Figure 8, in the fourth section CS4, the first surface 41 is inclined in the second direction 102 with respect to the corner rake face 34. In other words, the first surface 41 is inclined with respect to the fifth virtual line 115 in the direction from the base 2 to the top surface 1. The second direction 102 is the direction from the base 2 to the top surface 1. The second direction 102 is, for example, perpendicular to the base 2. The fifth virtual line 115 passes through both ends of the corner rake face 34 in the fourth section CS4. From another point of view, in the fourth section CS4, the fifth virtual line 115 passes through the point of contact between the corner cutting edge 13 and the corner rake face 34 and the sixth connection point 126. In other words, the fifth virtual line 115 passes through the reference point 98 and the sixth connection point 126. The inclination angle of the first surface 41 with respect to the fifth virtual line 115 is set to the third angle θ3. The third angle θ3 is, for example, 15°. The third angle θ3 may also be, for example, between 8° and 20°.

[0085] As shown in Figure 8, in the fourth section CS4, the second surface 42 is closer to the base surface 2 than the first surface 41. In the fourth section CS4, the second surface 42 is inclined in the first direction 101 with respect to the first surface 41. In other words, in the fourth section CS4, the second surface 42 approaches the base surface 2 as it moves away from the reference point 98. The corner rake face 34 and the third rake face 33 are each closer to the base surface 2 than the ridge line 20. In the fourth section CS4, the boundary line between the first rake face 31 and the first intermediate rake face 21 may intersect with the second surface 42.

[0086] In the first cross section CS1 (see Figure 5), the second cross section CS2 (see Figure 6), and the third cross section CS3 (see Figure 7), the first scoop portion 61 and the third scoop portion 63 are each curved and convex outwards. However, in other cross sections perpendicular to the bisector 99, the first scoop portion 61 and the third scoop portion 63 may also be curved and convex outwards. In other words, in a cross section perpendicular to the bisector 99, regardless of the distance between the reference point 98 and the cross section, the first scoop portion 61 and the third scoop portion 63 may each be curved and convex outwards. In a cross section perpendicular to the bisector 99, regardless of the distance between the reference point 98 and the cross section, the first scoop portion 61 and the third scoop portion 63 may each be substantially curved and convex outwards. In a cross-section perpendicular to the bisector 99 and located between the reference point 98 and the boundary between the projection 4 and the rising surface 6, the second scoop portion 62 and the fourth scoop portion 64 may each be straight.

[0087] In a cross-section perpendicular to the bisector 99 and located between the reference point 98 and the boundary between the projection 4 and the rising surface 6, the radii of curvature of the first rake face 31 and the second rake face 32 may increase as the distance from the reference point 98 increases. In a cross-section perpendicular to the bisector 99 and located between the reference point 98 and the boundary between the projection 4 and the rising surface 6, the ratio of the height of the first rake face 31 to the width of the first rake face 31 may decrease as the distance from the reference point 98 increases. In a cross-section perpendicular to the bisector 99 and located between the reference point 98 and the boundary between the projection 4 and the rising surface 6, the ratio of the height of the second rake face 32 to the width of the second rake face 32 may decrease as the distance from the reference point 98 increases.

[0088] In a cross-section perpendicular to the bisector 99, the projection 4 may be a curved shape that is convex outward, regardless of the distance between the reference point 98 and the cross-section. 。

[0089] As the distance from the reference point 98 increases, the radius of curvature of the projection 4 in the cross section perpendicular to the bisector 99 may increase. As the distance from the reference point 98 increases, the ratio of the height of the projection 4 to the width of the projection 4 in the cross section perpendicular to the bisector 99 may decrease.

[0090] In a cross section perpendicular to the bisector 99, the distance between the first cutting edge 11 and the projection 4 in the first direction 101 may increase as the distance from the reference point 98 increases. In a cross section perpendicular to the bisector 99, the distance between the second cutting edge 12 and the projection 4 in the first direction 101 may increase as the distance from the reference point 98 increases.

[0091] In a cross-section perpendicular to the bisector 99 and located between the reference point 98 and the boundary between the projection 4 and the rising surface 6, the first intermediate rake face 21 may be concave. In other words, in a cross-section perpendicular to the bisector 99 and located between the reference point 98 and the boundary between the projection 4 and the rising surface 6, the first intermediate rake face 21 may be a curved shape that is convex inward.

[0092] In a cross-section perpendicular to the bisector 99 and located between the reference point 98 and the boundary between the projection 4 and the rising surface 6, the second intermediate rake face 22 may be concave. In other words, in a cross-section perpendicular to the bisector 99 and located between the reference point 98 and the boundary between the projection 4 and the rising surface 6, the second intermediate rake face 22 may be a curved shape that is convex inward.

[0093] (Second Embodiment) Next, the configuration of the cutting insert 100 according to the second embodiment will be described. The cutting insert 100 according to the second embodiment mainly consists of the first cutting edge 11 and the second cutting edge 12 when viewed in the first direction. Na The configuration of the cutting insert 100 differs from that of the cutting insert 100 according to the first embodiment in the corners, but otherwise it is substantially the same as that of the cutting insert 100 according to the first embodiment. The following description will focus on the differences from the configuration of the cutting insert 100 according to the first embodiment.

[0094] Figure 9 is a schematic plan view showing the configuration of the cutting insert 100 according to the second embodiment. When viewed in the first direction 101, the angle between the first straight section 14 and the second straight section 15 (first angle θ1) is, for example, 100°. The first angle θ1 may be, for example, 95° or more and 105° or less.

[0095] Figure 10 is an enlarged schematic diagram showing region X in Figure 9. As shown in Figure 10, the second surface 42 may be composed of a first portion 51 and a second portion 52. When viewed in the first direction 101, the angle between the first cutting edge 11 and the second cutting edge 12 (second angle θ2) is, for example, 80°. The second angle θ2 may be, for example, 75° or more and 85° or less.

[0096] Figure 11 is a schematic longitudinal section along the line XI-XI in Figure 10. The third width W3 of the projection 4 is, for example, 0.16 mm. The third width W3 may be, for example, 0.10 mm or more and 0.20 mm or less. The third ratio of the projection 4 is, for example, 0.14. The third ratio may be, for example, 0.10 or more and 0.20 or less.

[0097] Figure 12 is a schematic longitudinal section along the line XII-XII in Figure 10. The fourth width W4 of the projection 4 is, for example, 0.71 mm. The fourth width W4 may be, for example, 0.30 mm or more and 2.00 mm or less. The ratio of the third width W3 to the fourth width W4 is, for example, 0.23. The ratio of the third width W3 to the fourth width W4 may be, for example, 0.05 or more and 0.5 or less. The fourth ratio of the projection 4 is, for example, 0.10. The fourth ratio may be, for example, 0.01 or more and 0.18 or less.

[0098] Figure 13 is a schematic longitudinal section along the line XIII-XIII in Figure 10. In the fourth section CS4, the boundary line between the first rake face 31 and the first intermediate rake face 21 may intersect with the first surface 41.

[0099] (Third embodiment) Next, the configuration of the cutting insert 100 according to the third embodiment will be described. The cutting insert 100 according to the third embodiment mainly consists of the first cutting edge 11 and the second cutting edge 12 when viewed in the first direction Na The configuration of the cutting insert 100 differs from that of the cutting insert 100 according to the first embodiment in the corners, but otherwise it is substantially the same as that of the cutting insert 100 according to the first embodiment. The following description will focus on the differences from the configuration of the cutting insert 100 according to the first embodiment.

[0100] Figure 14 is a schematic plan view showing the configuration of the cutting insert 100 according to the third embodiment. When viewed in the first direction 101, the angle between the first straight section 14 and the second straight section 15 (first angle θ1) is, for example, 145°. The first angle θ1 may be, for example, 140° or more and 150° or less.

[0101] Figure 15 is an enlarged schematic diagram showing region XV in Figure 14. When viewed in the first direction 101, the angle between the first cutting edge 11 and the second cutting edge 12 (second angle θ2) is, for example, 35°. The second angle θ2 may be, for example, 30° or more and 40° or less.

[0102] Figure 16 is a schematic longitudinal section along the line XVI-XVI in Figure 15. The third width W3 of the projection 4 is, for example, 0.05 mm. The third width W3 may be, for example, 0.02 mm or more and 0.08 mm or less. The third ratio of the projection 4 is, for example, 0.04. The third ratio may be, for example, 0.02 or more and 0.06 or less.

[0103] Figure 17 is a schematic longitudinal section along the line XVII-XVII in Figure 15. The fourth width W4 of the projection 4 is, for example, 0.17 mm. The fourth width W4 may be, for example, 0.10 mm or more and 0.30 mm or less. The ratio of the third width W3 to the fourth width W4 is, for example, 0.29. The ratio of the third width W3 to the fourth width W4 may be, for example, 0.1 or more and 0.6 or less. The fourth ratio of the projection 4 is, for example, 0.02. The fourth ratio may be, for example, 0.01 or more and 0.04 or less.

[0104] Figure 18 is a schematic longitudinal section along the line XVIII-XVIII in Figure 15. In the fourth section CS4, the seventh connection point 127 and the eighth connection point 128 may be located closer to the bottom surface 2 than the boundary line between the first rake face 31 and the first intermediate rake face 21.

[0105] Next, the effects and benefits of the cutting insert 100 according to this disclosure will be explained. Figure 19 is a schematic diagram showing the state of cutting a workpiece 200 using a cutting insert 100. As shown in Figure 19, when cutting a workpiece 200 using a cutting insert 100, the workpiece 200 is rotated around a rotation axis 130. The cutting insert 100 is attached to a tool body (not shown). The workpiece 200 is cut by feeding the cutting insert 100 in the direction of arrow A relative to the rotating workpiece 200.

[0106] When machining a workpiece 200, the depth of cut ap is set according to the target dimension of the workpiece 200. If the diameter of the workpiece 200 is to be reduced, the depth of cut ap is increased. If the diameter of the workpiece 200 is to be increased, the depth of cut ap is decreased. Therefore, if the diameter of the workpiece 200 is to be changed depending on the part of the workpiece 200 being cut, the depth of cut ap is changed during machining. As the depth of cut ap decreases, the width of the chips generated during cutting decreases. Conversely, as the depth of cut ap increases, the width of the chips generated during cutting increases.

[0107] When the chip width is small, a cutting insert 100 without the projection 4 may result in a larger chip curl diameter and poor chip handling performance. Specifically, for example, when the depth of cut ap is 0.5 mm or less, the chip curl diameter may increase, and chip handling performance may deteriorate. On the other hand, when the chip width is large, a cutting insert 100 with the projection 4 may experience increased force on the projection 4 from the chip, increasing cutting resistance. Specifically, for example, when the depth of cut ap is 1 mm or more, cutting resistance increases.

[0108] According to the cutting insert 100 of this disclosure, a projection 4 is provided on the top surface 1. In a cross section perpendicular to the bisector 99, the projection 4 is curved and convex outward. The ratio of the height (fourth height H4) of the projection 4 to the width (fourth width W4) of the projection 4 in the second cross section CS2 (fourth ratio) is smaller than the ratio of the height (third height H3) of the projection 4 to the width (third width W3) of the projection 4 in the first cross section CS1 (third ratio). The third distance D3 is greater than the first distance D1. The fourth distance D4 is greater than the second distance D2. As a result, when the depth of cut ap is small, the distance between the cutting edge and the projection 4 in the first direction 101 is small, and the projection 4 protrudes significantly outward, so the projection 4 can be used to effectively push back the chips. Conversely, when the depth of cut ap is large, the distance between the cutting edge and the projection 4 in the first direction 101 is large, and the projection 4 does not protrude significantly, so the projection 4 can flow the chips without pushing them back. As a result, it is possible to improve chip handling when the depth of cut ap is small, while reducing cutting resistance when the depth of cut ap is large.

[0109] According to the cutting insert 100 of this disclosure, the ratio of the height of the first rake face 31 to the width of the first rake face 31 in the second cross section CS2 is smaller than the ratio of the height (first height H1) of the first rake face 31 to the width (first width W1) in the first cross section CS1 (first ratio). The ratio of the height of the second rake face 32 to the width of the second rake face 32 in the second cross section CS2 is smaller than the ratio of the height (second height H2) of the second rake face 32 to the width (second width W2) in the first cross section CS1 (second ratio). As a result, when the depth of cut ap is small, the amount of chips drawn in in the direction from the top surface 1 to the bottom surface 2 is large because each of the first rake face 31 and the second rake face 32 protrudes significantly outward. Therefore, after drawing in a large amount of chips, the projection 4 can be used to push the chips back, thereby reducing the curl diameter of the chips. Conversely, when the depth of cut ap is large, the wedge angle of the cutting edge in the cross section perpendicular to the line bisector 99 can be increased. As a result, it is possible to improve the chip handling efficiency when the depth of cut ap is small, while improving the strength of the cutting edge when the depth of cut ap is large.

[0110] According to the cutting insert 100 of this disclosure, in the first cross section CS1, the first rake face 31 and the second rake face 32 are each curved and convex outward. In the first cross section CS1, the rake angle of the first rake face 31 (first rake angle θ11) increases as it approaches the projection 4 from the first cutting edge 11. In the first cross section CS1, the rake angle of the second rake face 32 (second rake angle θ12) increases as it approaches the projection 4 from the second cutting edge 12. Therefore, when the depth of cut ap is small, the amount of chip drawn in in the direction from the top surface 1 to the bottom surface 2 can be further increased. This makes it possible to more effectively improve the chip handling performance when the depth of cut ap is small.

[0111] According to the cutting insert 100 of this disclosure, in the second cross section CS2, the first rake face 31 and the second rake face 32 are each straight. Therefore, compared to the case where the first rake face 31 and the second rake face 32 are each curved, the strength of the cutting edge can be more effectively improved when the depth of cut ap is large.

[0112] According to the cutting insert 100 of this disclosure, in a cross section (fourth cross section CS4) that is parallel to the first direction 101 and includes the bisector 99, the first surface 41 is inclined with respect to the corner rake face 34 in the direction from the bottom surface 2 to the top surface 1. When the depth of cut ap is less than or equal to the radius of curvature of the corner cutting edge 13, the chip may flow along the bisector 99. In this case, according to the cutting insert 100 of this disclosure, the chip drawn in by the corner rake face 34 can be pushed back using the first surface 41. This improves the chip handling efficiency.

[0113] According to the cutting insert 100 of this disclosure, in a cross section (fourth cross section CS4) that is parallel to the first direction 101 and includes the bisector 99, the second surface 42 is located closer to the bottom surface 2 than the first surface 41. Therefore, when the depth of cut ap is large, the force with which the second surface 42 pushes back the chip can be reduced. This makes it possible to more effectively reduce cutting resistance when the depth of cut ap is large.

[0114] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described above, and all modifications within the meaning and scope of the claims are intended to be included. [Explanation of Symbols]

[0115] 1 Top surface, 2 Bottom surface, 4 Projection, 5 Flat surface, 6 Rising surface, 7 Inner circumferential surface, 8 Outer circumferential surface, 9 Through hole, 10 Cutting edge, 11 First cutting edge, 12 Second cutting edge, 13 Corner cutting edge, 14 First straight section, 15 Second straight section, 20 Ridge, 21 First intermediate rake face, 22 Second intermediate rake face, 31 First rake face, 32 Second rake face, 33 Third rake face, 34 Corner rake face, 41 First surface, 42 Second surface, 51 First section, 52 Second section, 53 Third section, 61 First rake section, 62 Second rake section, 63 Third rake section, 64 Fourth rake section, 71 First corner rake section, 72 Second corner rake section, 91 First end, 92 98 Reference point, 99 Bisector, 100 Cutting insert, 101 First direction, 102 Second direction, 111 First virtual line, 112 Second virtual line, 113 Third virtual line, 114 Fourth virtual line, 115 Fifth virtual line, 121 First connection point, 122 Second connection point, 123 Third connection point, 124 Fourth connection point, 125 Fifth connection point, 126 Sixth connection point, 127 Seventh connection point, 128 Eighth connection point, 130 Rotation axis, 200 Workpiece, A Arrow, CS1 First section, CS2 Second section, CS3 Third section, CS4 Fourth section, D1 First distance, D2 Second distance, D3 Third distance, D4 ​​Fourth distance, H1 First height, H2 Second height, H3 Third height, H4 Fourth height, O Center, R1 1st radius of curvature, R2 2nd radius of curvature, R3 3rd radius of curvature, R4 4th radius of curvature, W1 1st width, W2 2nd width, W3 3rd width, W4 4th width, ap depth of cut, θ1 1st angle, θ2 2nd angle, θ3 3rd angle, θ11 1st rake angle, θ12 2nd rake angle.

Claims

1. Top surface and, The bottom surface opposite the aforementioned top surface, It comprises an outer peripheral surface connected to each of the aforementioned top surface and bottom surface, The ridge line between the top surface and the outer surface is, The first cutting edge and A corner cutting edge connected to the first cutting edge, It includes a second cutting edge that is connected to the corner cutting edge and is opposite to the first cutting edge relative to the corner cutting edge, A projection is provided on the top surface, Viewed in a first direction from the top surface toward the bottom surface and perpendicular to the bottom surface, the projection extends along the line bisector of the angle between the first cutting edge and the second cutting edge. In a cross-section perpendicular to the aforementioned bisector, the projection is curved and convex outwards. In the first direction, the projection is provided in a position closer to the bottom surface than each of the first cutting edge and the second cutting edge. Viewed in the first direction, the intersection of the corner cutting edge and the bisector is used as the reference point. In a first cross-section perpendicular to the line bisector and at a distance of 0.5 mm from the reference point, the shortest distance between the first cutting edge and the projection in the first direction is defined as the first distance, and the shortest distance between the second cutting edge and the projection in the first direction is defined as the second distance. In a second cross-section perpendicular to the line bisector and with a distance of 1.5 mm from the reference point, if the shortest distance between the first cutting edge and the projection in the first direction is defined as the third distance, and the shortest distance between the second cutting edge and the projection in the first direction is defined as the fourth distance, The third distance is greater than the first distance. The aforementioned fourth distance is greater than the aforementioned second distance. The top surface further comprises a first intermediate rake face and a second intermediate rake face. Each of the first intermediate rake face and the second intermediate rake face is connected to the projection, In each of the first and second cross-sections, the first intermediate rake face and the second intermediate rake face are curved inwardly, In a cross-section perpendicular to the aforementioned bisector, the distance between the connection point between the projection and the first intermediate rake face and the connection point between the projection and the second intermediate rake face is defined as the width of the projection. In a cross-section perpendicular to the aforementioned bisector, a virtual line passing through the connection point between the projection and the first intermediate rake face and the connection point between the projection and the second intermediate rake face is defined as the third virtual line. In a cross-section perpendicular to the line bisector, if the distance between the point on the projection furthest from the third virtual line and the third virtual line is defined as the height of the projection, A cutting insert in which the ratio of the height of the projection to the width of the projection in the second cross-section is smaller than the ratio of the height of the projection to the width of the projection in the first cross-section.

2. The aforementioned top surface is, A first rake face connected to each of the first cutting edge and the first intermediate rake face, and located between the first cutting edge and the projection, It includes a second rake face connected to each of the second cutting edge and the second intermediate rake face, and a second rake face located between the second cutting edge and the projection, The width of the first rake face is defined as the distance between the point of contact between the first rake face and the first cutting edge in a cross section perpendicular to the line bisector and the connection point between the first rake face and the first intermediate rake face. The width of the second rake face is defined as the distance between the point of contact between the second rake face and the second cutting edge in a cross section perpendicular to the bisector and the connection point between the second rake face and the second intermediate rake face. In a cross-section perpendicular to the aforementioned line bisector, Let the first virtual line be the virtual line passing through the point of contact between the first rake face and the first cutting edge and the connection point between the first rake face and the first intermediate rake face. The height of the first rake face is defined as the distance between the point on the first rake face that is furthest from the first virtual line and the first virtual line. Let the second virtual line be the virtual line passing through the point of contact between the second rake face and the second cutting edge and the connection point between the second rake face and the second intermediate rake face. If the height of the second rake face is defined as the distance between the point on the second rake face that is furthest from the second virtual line and the second virtual line, The ratio of the height of the first rake face to the width of the first rake face in the second cross section is smaller than the ratio of the height of the first rake face to the width of the first rake face in the first cross section. The ratio of the height of the second rake face to the width of the second rake face in the second cross section is smaller than the ratio of the height of the second rake face to the width of the second rake face in the first cross section. Let the line parallel to the base and perpendicular to the line bisector be the fourth imaginary line. In a cross section perpendicular to the line bisector, the angle between the fourth virtual line and the tangent to the first rake face is defined as the rake angle of the first rake face. In a cross section perpendicular to the aforementioned bisector, if the angle between the fourth virtual line and the tangent to the second rake face is defined as the rake angle of the second rake face, The cutting insert according to claim 1, wherein in the first cross-section, each of the first rake face and the second rake face is curved and convex outward, and the rake angle of the first rake face increases as it approaches the projection from the first cutting edge, and the rake angle of the second rake face increases as it approaches the projection from the second cutting edge.

3. The cutting insert according to claim 2, wherein in the second cross-section, each of the first rake face and the second rake face is linear.

4. The aforementioned top surface is, A third rake face is located between the first rake face and the second rake face and is formed by the projection, The invention further includes a corner rake face located between the third rake face and the corner cutting edge, The third scoop face is, With respect to the corner rake face, the first surface is opposite to the corner cutting edge, It has a second surface that is connected to the first surface and is opposite to the corner scuff surface relative to the first surface, The cutting insert according to claim 2 or 3, wherein, in a cross section parallel to the first direction and including the bisector, the first surface is inclined in a second direction toward the top surface with respect to the corner rake face, and the second surface is located closer to the bottom surface than the first surface.

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