Cutting Tools

Abstract

The cutting tool has a top surface, a bottom surface, and a side surface. The bottom surface is located on the opposite side of the top surface. The side surface is continuous with each of the top surface and the bottom surface. The ridgeline between the top surface and the side surface includes: a tip cutting edge portion, which is curved and has a first end and a second end located on the opposite side of the first end; a main cutting edge portion, which is continuous with the first end; and a wiper cutting edge portion, which is continuous with the second end. The top surface includes: a first rake face, which is continuous with the wiper cutting edge portion; a second rake face, which is continuous with the main cutting edge portion; and a third rake face, which is continuous with the tip cutting edge portion and is continuous with each of the first rake face and the second rake face. The boundary line between the second rake face and the third rake face is separated from the first end and is continuous with the main cutting edge portion.

Description

Technical Field

[0001] The present invention relates to a cutting tool. This application claims priority based on Japanese Patent Application No. 2019-060276 filed on March 27, 2019, the entire contents of which are hereby incorporated by reference. Background Art

[0002] Japanese Patent Application Laid-Open No. 2007-44779 (Patent Document 1) discloses a throw-away insert (cutting tool) and a milling cutter using the cutting tool.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-44779 Summary of the invention

[0006] The cutting tool involved in the present invention includes a top surface, a bottom surface and a side surface. The bottom surface is located on the opposite side of the top surface. The side surface is connected to each of the top surface and the bottom surface. The ridge between the top surface and the side surface includes: a tip cutting edge portion, which is curved and has a first end and a second end located on the opposite side of the first end; a main cutting edge portion, which is connected to the first end; and a finishing cutting edge portion, which is connected to the second end. The top surface includes: a first rake face, which is connected to the finishing cutting edge portion; a second rake face, which is connected to the main cutting edge portion; and a third rake face, which is connected to the tip cutting edge portion and is connected to each of the first rake face and the second rake face. The boundary line between the second rake face and the third rake face is separated from the first end and connected to the main cutting edge portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic perspective view showing the structure of the cutting tool according to the present embodiment.

[0008] Figure 2 It is a schematic plan view showing the structure of the cutting tool according to the present embodiment.

[0009] Figure 3 is along Figure 2 Schematic cross-sectional view of line III-III.

[0010] Figure 4 is along Figure 2 Schematic cross-sectional view of line IV-IV.

[0011] Figure 5 yes Figure 2 An enlarged schematic plan view of region V of FIG.

[0012] Figure 6 yes Figure 5 An enlarged schematic plan view of region VI.

[0013] Figure 7 is along Figure 5 A schematic cross-sectional view of line VII-VII.

[0014] Figure 8 yes Figure 7 An enlarged schematic cross-sectional view of region VIII of FIG.

[0015] Fig. 9 It is a schematic plan view showing the structure of a cutting tool according to a comparative example. DETAILED DESCRIPTION

[0016] [Problems to be Solved by the Invention]

[0017] There is a demand for further improvement in chipping resistance in cutting tools.

[0018] An object of the present invention is to provide a cutting tool capable of improving chipping resistance.

[0019] [Effects of the Invention]

[0020] According to the present invention, a cutting tool capable of improving chipping resistance can be provided.

[0021] [Description of Embodiments of the Invention]

[0022] First, embodiments of the present invention will be described by way of examples.

[0023] (1) The cutting tool 100 according to the present invention includes a top surface 50, a bottom surface 60, and a side surface 70. The bottom surface 60 is located on the opposite side of the top surface 50. The side surface 70 is continuous with each of the top surface 50 and the bottom surface 60. The ridgeline 80 between the top surface 50 and the side surface 70 includes: a tip cutting edge portion 83 which is curved and has a first end 86 and a second end 85 located on the opposite side of the first end 86; a main cutting edge portion 82 which is continuous with the first end 86; and a wiper cutting edge portion 81 which is continuous with the second end 85. The top surface 50 includes: a first rake face 51 which is continuous with the wiper cutting edge portion 81; a second rake face 52 which is continuous with the main cutting edge portion 82; and a third rake face 53 which is continuous with the tip cutting edge portion 83 and is continuous with each of the first rake face 51 and the second rake face 52. The boundary line 3 between the second rake face 52 and the third rake face 53 is separated from the first end 86 and continues to the main cutting edge portion 82 .

[0024] (2) According to the cutting tool 100 involved in the above (1), the third rake face 53 may have a first region 1 continuous with the first rake face 51, and a second region 2 continuous with the second rake face 52. In a cross section perpendicular to the bottom surface 60 and intersecting each of the main cutting edge portion 82 and the smoothing cutting edge portion 81, the first region 1 may be convex and the second region 2 may be concave.

[0025] (3) According to the cutting tool 100 involved in (1) or (2) above, when observed in a direction perpendicular to the bottom surface 60, in a direction parallel to the bottom surface 60 and parallel to the main cutting edge portion 82, when the distance between the boundary point 4 between the boundary line 3 and the main cutting edge portion 82 and the second end 85 is set to the first distance D1, and the distance between the second end 85 and the first end 86 is set to the second distance D2, the first distance D1 can be greater than 1.2 times and less than 6 times the second distance D2.

[0026] (4) According to the cutting tool 100 involved in the above (3), in a cross section perpendicular to the bottom surface 60 and inclined at 25 degrees relative to the finishing cutting edge portion 81, the third rake face 53 can have an arc-shaped recessed portion, and the curvature radius R of the recessed portion can be greater than 0.5 times the first distance D1.

[0027] (5) According to the cutting tool 100 according to any one of (1) to (4) above, the rake angle of the second rake face 52 may be larger than the rake angle of the first rake face 51 .

[0028] [Details of the embodiments of the present invention]

[0029] Next, the details of the embodiments of the present invention will be described based on the drawings. It should be noted that in the following drawings, the same reference numerals represent the same parts or corresponding parts, and their description will not be repeated.

[0030] First, the structure of the cutting tool 100 according to the present embodiment will be described. Figure 1 It is a schematic perspective view showing the structure of the cutting tool 100 according to the present embodiment.

[0031] like Figure 1 As shown, the cutting tool 100 mainly has a top surface 50, a bottom surface 60 and a side surface 70. The bottom surface 60 is located on the opposite side of the top surface 50. The bottom surface 60 is a flat surface. The side surface 70 is continuous with each of the top surface 50 and the bottom surface 60. The side surface 70 is annular. The cutting tool 100 is provided with a tool mounting hole 9. The tool mounting hole 9 is a through hole opened in each of the top surface 50 and the bottom surface 60.

[0032] The ridgeline 80 between the top surface 50 and the side surface 70 includes a major cutting edge portion 82, a nose cutting edge portion 83, a wiper cutting edge portion 81, and a minor cutting edge portion 84. The side surface 70 includes a first side surface region 74, a second side surface region 76, and a third side surface region 73. The first side surface region 74 is continuous with each of the wiper cutting edge portion 81 and the minor cutting edge portion 84. The second side surface region 76 is continuous with the major cutting edge portion 82. The second side surface region 76 includes a first side surface portion 72 and a second side surface portion 75. The third side surface region 73 is continuous with the nose cutting edge portion 83.

[0033] The first side surface portion 72 is located between the bottom surface 60 and the second side surface portion 75. The first side surface portion 72 is continuous with, for example, each of the second side surface portion 75 and the third side surface region 73. The third side surface region 73 is located between the first side surface region 74 and the second side surface region 76. The third side surface region 73 is continuous with each of the first side surface region 74 and the second side surface region 76. The third side surface region 73 is located between the first side surface region 74 and the first side surface portion 72. The third side surface region 73 is located between the first side surface region 74 and the second side surface portion 75.

[0034] Figure 2 It is a schematic plan view showing the structure of the cutting tool 100 according to the present embodiment. Figure 2 The top surface 50 is viewed from a direction perpendicular to the bottom surface 60. Each of the finishing cutting edge portion 81 and the main cutting edge portion 82 is, for example, curved. The auxiliary cutting edge portion 84 is, for example, straight. The auxiliary cutting edge portion 84 may be curved. Figure 2 As shown in the figure, when viewed in a direction perpendicular to the bottom surface 60, each of the wiper cutting edge portion 81, the main cutting edge portion 82, and the minor cutting edge portion 84 may be in a straight line shape. The tip cutting edge portion 83 is in a curved line shape. The tip cutting edge portion 83 has a first end 86 and a second end 85 located on the opposite side of the first end 86. The main cutting edge portion 82 is connected to one end (the first end 86) of the tip cutting edge portion 83. The wiper cutting edge portion 81 is connected to the other end (the second end 85) of the tip cutting edge portion 83. The tip cutting edge portion 83 is located between the main cutting edge portion 82 and the wiper cutting edge portion 81.

[0035] One end of the wiper cutting edge portion 81 is the other end (second end 85) of the blade tip cutting edge portion 83. The other end (third end 87) of the wiper cutting edge portion 81 is continuous with the minor cutting edge portion 84. When viewed in a direction perpendicular to the bottom surface 60, the cutting tool 100 extends in the long side direction Y and the short side direction X. The main cutting edge portion 82 extends in the long side direction Y. The wiper cutting edge portion 81 extends in the short side direction X. The extension direction of the main cutting edge portion 82 is inclined at an angle of approximately 90° relative to the extension direction of the wiper cutting edge portion 81. The minor cutting edge portion 84 is inclined toward the tool mounting hole 9 relative to the wiper cutting edge portion 81. The extension direction of the minor cutting edge portion 84 is inclined at an angle greater than 0° and less than 90° relative to the extension direction of the wiper cutting edge portion 81. The minor cutting edge portion 84 is inclined relative to each of the long side direction Y and the short side direction X.

[0036] The top surface 50 has a first rake face 51, a second rake face 52, a third rake face 53, a fourth rake face 54, and a center flat portion 55. The first rake face 51 is continuous with the smoothing cutting edge portion 81. The first rake face 51 has a first land portion 41 and a first rake face portion 31. The first land portion 41 is continuous with the smoothing cutting edge portion 81. The first rake face portion 31 is continuous with the first land portion 41. Figure 2 As shown, when viewed in a direction perpendicular to the bottom surface 60 , the first land portion 41 is located between the first rake face portion 31 and the wiper cutting edge portion 81 .

[0037] The second rake face 52 is continuous with the main cutting edge portion 82. The second rake face 52 has a second land portion 42 and a second rake face portion 32. The second land portion 42 is continuous with the main cutting edge portion 82. The second rake face portion 32 is continuous with the second land portion 42. Figure 2 As shown, when viewed in a direction perpendicular to the bottom surface 60 , the second land portion 42 is located between the second rake face portion 32 and the major cutting edge portion 82 .

[0038] The fourth rake face 54 is continuous with the minor cutting edge portion 84. The fourth rake face 54 has a fourth land portion 44 and a fourth rake face portion 34. The fourth land portion 44 is continuous with the minor cutting edge portion 84. The fourth rake face portion 34 is continuous with the fourth land portion 44. Figure 2 As shown, when viewed in a direction perpendicular to the bottom surface 60 , the fourth land portion 44 is located between the fourth rake face portion 34 and the minor cutting edge portion 84 .

[0039] The central flat portion 55 is continuous with the tool mounting hole 9. When viewed in a direction perpendicular to the bottom surface 60, the central flat portion 55 is located between the tool mounting hole 9 and each of the first rake face 51, the second rake face 52, the third rake face 53, and the fourth rake face 54. The central flat portion 55 is continuous with each of the first rake face 51, the second rake face 52, the third rake face 53, and the fourth rake face 54. The central flat portion 55 is provided with, for example, four recessed portions 61. Figure 2 As shown, when viewed in a direction perpendicular to the bottom surface 60 , the recessed portion 61 is provided between the first rake surface 51 and the tool mounting hole 9 and between the fourth rake surface 54 and the tool mounting hole 9 .

[0040] Figure 3 is along Figure 2 Schematic cross-sectional view of line III-III. Figure 3 It is a cut surface that is perpendicular to the bottom surface 60 , intersects the tool mounting hole 9 , and is perpendicular to the wiper cutting edge portion 81 .

[0041] like Figure 3 As shown, the first rake face portion 31 is inclined toward the bottom surface 60 relative to the first land portion 41. The first rake face 51 has a rake angle (first rake angle θ1). When the first rake face 51 has the first land portion 41, the rake angle of the first rake face 51 is the rake angle of the first rake face portion 31. The first rake angle θ1 is, for example, not less than 5° and not more than 20°.

[0042] The first side region 74 is continuous with the smoothing cutting edge portion 81. The first side region 74 is continuous with the minor cutting edge portion 84. The first side region 74 is inclined toward the tool mounting hole 9 relative to a plane perpendicular to the bottom surface 60. The inclination angle (third inclination angle θ3) of the first side region 74 relative to the plane perpendicular to the bottom surface 60 is, for example, 10° to 30°. The first side region 74 is continuous with the bottom surface 60. The first side region 74 is used as a flank surface.

[0043] Figure 4 is along Figure 2 Schematic cross-sectional view of line IV-IV. Figure 4 It is a cut surface that is perpendicular to the bottom surface 60 , intersects with the tool mounting hole 9 , and is perpendicular to the main cutting edge portion 82 .

[0044] like Figure 4 As shown, the second rake face portion 32 is inclined toward the bottom surface 60 relative to the second land portion 42. The second rake face 52 has a rake angle (second rake angle θ2). In the case where the second rake face 52 has the second land portion 42, the rake angle of the second rake face 52 is the rake angle of the second rake face portion 32. The second rake angle θ2 is, for example, not less than 10° and not more than 35°. The rake angle (second rake angle θ2) of the second rake face 52 may be greater than the rake angle (first rake angle) of the first rake face 51.

[0045] The second side region 76 has a first side portion 72 and a second side portion 75. The second side portion 75 is continuous with the main cutting edge portion 82. The second side portion 75 is inclined toward the tool mounting hole 9 side relative to a plane perpendicular to the bottom surface 60. The first side portion 72 is continuous with the second side portion 75. In a direction perpendicular to the bottom surface 60, the first side portion 72 is located between the second side portion 75 and the bottom surface 60. The first side portion 72 is inclined relative to a plane perpendicular to the bottom surface 60. The inclination angle (5th angle θ5) of the first side portion 72 relative to the plane perpendicular to the bottom surface 60 is greater than the inclination angle (4th angle θ4) of the second side portion 75 relative to the plane perpendicular to the bottom surface 60. The second side region 76 is used as a back cutting surface.

[0046] Figure 5 yes Figure 2 An enlarged schematic plan view of region V of FIG. Figure 5 As shown, the boundary line (first boundary line 5) between the first rake face 51 and the third rake face 53 is continuous with the second end 85 of the nose cutting edge portion 83. On the other hand, the boundary line (second boundary line 3) between the second rake face 52 and the third rake face 53 is separated from the first end 86 of the nose cutting edge portion 83. The second boundary line 3 is continuous with the main cutting edge portion 82.

[0047] like Figure 5 As shown, the third rake face 53 is connected to the cutting edge portion 83. The third rake face 53 has a first region 1 and a second region 2. The first region 1 is connected to the first rake face 51. The second region 2 is connected to the second rake face 52. The first region 1 is located between the first rake face 51 and the second region 2. The second region 2 is located between the second rake face 52 and the first region 1. The second region 2 is connected to the first region 1. The first region 1 is connected to the cutting edge portion 83. The second region 2 is connected to the main cutting edge portion 82. The boundary line (third boundary line 6) between the first region 1 and the second region 2 can be connected to the first end 86.

[0048] Figure 6 yes Figure 5 An enlarged schematic plan view of region VI of FIG. Figure 6 As shown, the boundary line (second boundary line 3) between the second rake face 52 and the third rake face 53 may have a first straight portion 7 and a second straight portion 8. The first straight portion 7 is inclined relative to each of the main cutting edge portion 82 and the wiper cutting edge portion 81. The second straight portion 8 is parallel to the wiper cutting edge portion 81. The second straight portion 8 is continuous with the first straight portion 7. The second straight portion 8 is inclined relative to the first straight portion 7. The second straight portion 8 is continuous with the main cutting edge portion 82. The first straight portion 7 is continuous with the center flat portion 55 (see Figure 5 ).

[0049] like Figure 6 As shown, the first region 1 has a first region land portion 21 and a first region rake face portion 11. The first region land portion 21 is continuous with the cutting edge portion 83. The first region rake face portion 11 is continuous with the first region land portion 21. The first region rake face portion 11 is inclined toward the bottom surface 60 relative to the first region land portion 21. Figure 6 As shown, when viewed in a direction perpendicular to the bottom surface 60 , the first-region land portion 21 is located between the first-region rake face portion 11 and the nose cutting edge portion 83 .

[0050] like Figure 6 As shown, the second region 2 has a second region land portion 22 and a second region rake face portion 12. The second region land portion 22 is continuous with the main cutting edge portion 82. The second region rake face portion 12 is continuous with the second region land portion 22. The second region rake face portion 12 is inclined toward the bottom surface 60 relative to the second region land portion 22. Figure 6 As shown, when viewed in a direction perpendicular to the bottom surface 60 , the second region land portion 22 is located between the second region rake face portion 12 and the major cutting edge portion 82 .

[0051] The first region land portion 21 is continuous with each of the first region land portion 41 and the second region land portion 22. The first region land portion 21 is located between the first region land portion 41 and the second region land portion 22. The second region land portion 22 is continuous with each of the second region land portion 42 and the first region land portion 21. The second region land portion 22 is located between the second region land portion 42 and the first region land portion 21. The first straight portion 7 is a boundary between the second region rake face portion 12 and the second rake face portion 32. The second straight portion 8 is a boundary between the second region land portion 42 and the second region land portion 22.

[0052] like Figure 6 As shown, when viewed in a direction perpendicular to the bottom surface 60, in a direction parallel to the bottom surface 60 and parallel to the main cutting edge portion 82, the distance between the boundary point 4 between the second boundary line 3 and the main cutting edge portion 82 and the second end 85 of the cutting edge portion 83 is set as the first distance D1, and the distance between the second end 85 and the first end 86 is set as the second distance D2. In this case, the first distance D1 is, for example, more than 1.2 times and less than 6 times the second distance D2. The first distance D1 may be more than 1.3 times the second distance D2, or may be more than 1.4 times the second distance D2. The first distance D1 may be less than 6 times the second distance D2, or may be less than 5.5 times the second distance D2. It should be noted that, when viewed in a direction perpendicular to the bottom surface 60, the direction parallel to the bottom surface 60 and parallel to the main cutting edge portion 82 is a direction parallel to a straight line obtained by projecting a straight line including the main cutting edge portion 82 onto a plane including the bottom surface 60.

[0053] Figure 7 is along Figure 5 Schematic cross-sectional view of line VII-VII. Figure 7 The cut surface is perpendicular to the bottom surface 60 and inclined at 25° with respect to the smoothing cutting edge portion 81. Figure 7 In the embodiment, the inclination angle (the sixth angle θ6) of the cut surface 10 relative to the smoothing cutting edge portion 81 is 25°. The cut surface 10 may extend through the boundary (the third end 87) between the smoothing cutting edge portion 81 and the minor cutting edge portion, or may intersect the smoothing cutting edge portion 81. The cut surface 10 intersects the major cutting edge portion 82.

[0054] Figure 8 yes Figure 7 An enlarged schematic cross-sectional view of region VIII of FIG. Figure 8 In the example, the ratio of the vertical dimension to the horizontal dimension is increased. Figure 8 As shown, in the cut surface 10 perpendicular to the bottom surface 60 and intersecting each of the main cutting edge portion 82 and the smoothing cutting edge portion 81, the first region 1 is convex and the second region 2 is concave. The convex shape is a shape that protrudes from the bottom surface 60 toward the top surface 50. From another point of view, the convex shape is a shape that is bent outward. The concave shape is a shape that is concave in the direction from the top surface 50 toward the bottom surface 60. From another point of view, the concave shape is a shape that is bent inward. The boundary line (third boundary line 6) between the first region 1 and the second region 2 is the inflection point of the third rake face 53.

[0055] In the cut surface 10, the first region 1 is an arc-shaped convex portion, and the second region 2 is an arc-shaped concave portion. The curvature radius R of the arc-shaped concave portion may be 0.5 times or more of the first distance D1. The curvature radius R of the arc-shaped concave portion may be 0.6 times or more of the first distance D1, or may be 0.7 times or more of the first distance D1.

[0056] In the direction perpendicular to the bottom surface 60, the second rake surface 52 is arranged at a position higher than the second region 2. From another point of view, the distance between the bottom surface 60 and the second rake surface 52 is greater than the distance between the bottom surface 60 and the second region 2. In the direction perpendicular to the bottom surface 60, the first region 1 is arranged at a position lower than the first rake surface 51. From another point of view, the distance between the bottom surface 60 and the first rake surface 51 is greater than the distance between the bottom surface 60 and the first region 1.

[0057] Next, the effects of the cutting tool 100 according to the present embodiment will be described.

[0058] According to the cutting tool 100 involved in the present embodiment, the top surface 50 includes: a first rake face 51, which is continuous with the smoothing cutting edge portion 81; a second rake face 52, which is continuous with the main cutting edge portion 82; and a third rake face 53, which is continuous with the tip cutting edge portion 83 and is continuous with each of the first rake face 51 and the second rake face 52. The boundary line 3 between the second rake face 52 and the third rake face 53 is separated from the first end 86 and is continuous with the main cutting edge portion 82. As a result, the thickness near the tip cutting edge portion 83 can be increased compared with the cutting tool 100 in which the boundary line 3 between the second rake face 52 and the third rake face 53 is continuous with the first end 86. In addition, when viewed in cross section, the second rake face 52 and the third rake face 53 are smoothly connected to each other. Therefore, on the rake face, the magnitude of the gradient of the maximum principal stress can be reduced. As a result, the chipping resistance is improved.

[0059] Furthermore, according to the cutting tool 100 involved in the present embodiment, the third rake face 53 may have a first region 1 continuous with the first rake face 51, and a second region 2 continuous with the second rake face 52. In a cross section perpendicular to the bottom surface 60 and intersecting each of the main cutting edge portion 82 and the smoothing cutting edge portion 81, the first region 1 may be convex and the second region 2 may be concave. Thus, the curling diameter of the chips generated during the cutting process can be reduced, thereby improving the chip discharge performance.

[0060] Furthermore, according to the cutting tool 100 involved in the present embodiment, when viewed in a direction perpendicular to the bottom surface 60, in a direction parallel to the bottom surface 60 and parallel to the main cutting edge portion 82, when the distance between the boundary point 4 between the boundary line 3 and the main cutting edge portion 82 and the second end 85 is set as the first distance D1, and the distance between the second end 85 and the first end 86 is set as the second distance D2, the first distance D1 can be 1.2 times or more and 6 times or less of the second distance D2. By setting the first distance D1 to 1.2 times or more of the second distance D2, the chipping resistance can be improved. By setting the first distance D1 to 6 times or less of the second distance D2, the chip discharge performance can be improved.

[0061] Furthermore, according to the cutting tool 100 involved in this embodiment, in a cross section perpendicular to the bottom surface 60 and inclined at 25° with respect to the smoothing cutting edge portion 81, the third rake face 53 may have an arc-shaped concave portion, and the curvature radius R of the concave portion may be 0.5 times or more of the first distance D1. Thus, the chipping resistance can be improved.

[0062] Furthermore, according to the cutting tool 100 according to the present embodiment, the rake angle of the second rake face 52 can be larger than the rake angle of the first rake face 51. Thus, the chip discharge performance can be improved.

[0063] Example

[0064] Next, the simulation results of the gradient of the maximum principal stress on the rake face will be described.

[0065] First, simulation models of the cutting tool 100 involved in Sample 1 and Sample 2 were prepared. The cutting tool 100 involved in Sample 1 is an embodiment and has Figure 6 The cutting tool 100 involved in Sample 2 is a comparative example and has Fig. 9 The shape shown. Fig. 9 As shown, in the cutting tool 100 according to Sample 2, the boundary line 3 between the second rake face 52 and the third rake face 53 continues to the first end 86 .

[0066] The simulation model of the cutting tool 100 involved in Samples 1 and 2 is used to calculate the gradient of the maximum principal stress on the front cutting face. NX8.0 provided by SIEMENS is used as the simulation software. A load is applied in a range of 0.2 mm in width and 3 mm in height along the main cutting edge portion 82 and the first end 86. The direction of the load is set to a direction perpendicular to the bottom surface 60. The load is set to 1000 N. The feed amount (fz) of each cutting edge is assumed to be 0.2 mm / tooth. The grid size is set to 0.05 mm.

[0067] [Table 1]

[0068] Sample No. The maximum value of the gradient of the maximum principal stress Sample 1 732MPa / mm Sample 2 1478MPa / mm

[0069] Table 1 shows the maximum value of the gradient of the maximum principal stress on the front face of the cutting tool 100 involved in Sample 1 and Sample 2. As shown in Table 1, the maximum value of the gradient of the maximum principal stress on the front face of the cutting tool 100 involved in Sample 1 is 732 MPa / mm. On the other hand, the maximum value of the gradient of the maximum principal stress on the front face of the cutting tool 100 involved in Sample 2 is 1478 MPa / mm. From the above results, it can be confirmed that the cutting tool 100 involved in Sample 1 can reduce the gradient of the maximum principal stress on the front face compared with the cutting tool 100 involved in Sample 2.

[0070] The embodiments and examples disclosed herein are to be considered in all respects as illustrative rather than restrictive. The scope of the present invention is not indicated by the above description but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

[0071] Description of the label

[0072] 1: 1st area; 2: 2nd area; 3: 2nd boundary line (boundary line); 4: boundary point; 5: 1st boundary line; 6: 3rd boundary line; 7: 1st straight line; 8: 2nd straight line; 9: tool mounting hole; 10: cutting surface; 11: 1st area rake face; 12: 2nd area rake face; 21: 1st area margin; 22: 2nd area margin; 31: 1st rake face; 32: 2nd rake face; 33: 3rd rake face; 34: 4th rake face; 41: 1st margin; 42: 2nd margin; 43: 3rd margin; 44: 4th margin; 50: top surface; 51: 1st rake face; 52: 2nd rake face; 53: 3rd rake face; 54: 4th rake face Blade face; 55: center flat portion; 60: bottom surface; 61: concave portion; 70: side surface; 72: 1st side surface portion; 73: 3rd side surface area; 74: 1st side surface area; 75: 2nd side surface portion; 76: 2nd side surface area; 80: ridgeline; 81: finishing cutting edge portion; 82: main cutting edge portion; 83: tip cutting edge portion; 84: secondary cutting edge portion; 85: 2nd end; 86: 1st end; 87: 3rd end; 100: cutting tool; D1: 1st distance; D2: 2nd distance; R: radius of curvature; X: short side direction; Y: long side direction; θ1: 1st rake angle; θ2: 2nd rake angle; θ3: 3rd inclination angle; θ4: 4th inclination angle; θ5: 5th inclination angle; θ6: 6th inclination angle.

Claims

1. A cutting tool comprising: Top surface; a bottom surface located on an opposite side of the top surface; as well as a side surface which is continuous with each of the top surface and the bottom surface, Wherein, the ridge line between the top surface and the side surface includes: The cutting edge portion of the blade tip is curved and has a first end and a second end located on the opposite side of the first end. a main cutting edge portion, which is continuous with the first end, a wiping cutting edge portion, which is continuous with the second end, and one end of the wiping cutting edge portion is the second end, and A secondary cutting edge portion, the other end of the polishing cutting edge portion is connected to the secondary cutting edge portion, The top surface comprises: a first rake face, which is continuous with the polishing cutting edge portion, a second rake face, which is continuous with the main cutting edge portion, and a third rake face that is continuous with the tip cutting edge portion and is continuous with each of the first rake face and the second rake face, A boundary line between the second rake face and the third rake face is separated from the first end and continues with the main cutting edge portion. The third rake face has a first region connected to the first rake face and a second region connected to the second rake face, and In a cross section perpendicular to the bottom surface and intersecting each of the main cutting edge portion and the wiper cutting edge portion, the first region is convex and the second region is concave, The third rake face has an arc-shaped recessed portion in a cross section perpendicular to the bottom surface and inclined at 25° with respect to the smoothing cutting edge portion, and the cross section extends through a boundary between the smoothing cutting edge portion and the minor cutting edge portion.

2. The cutting tool according to claim 1, wherein: When observed in a direction perpendicular to the bottom surface, in a direction parallel to the bottom surface and parallel to the main cutting edge portion, when the distance between the boundary point between the boundary line and the main cutting edge portion and the second end is set as the first distance, and the distance between the second end and the first end is set as the second distance, the first distance is not less than 1.2 times and not more than 6 times the second distance.

3. The cutting tool according to claim 2, wherein: The curvature radius of the concave portion is greater than or equal to 0.5 times the first distance.

4. The cutting tool according to any one of claims 1 to 3, wherein: The rake angle of the second rake face is greater than the rake angle of the first rake face.

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