The present disclosure relates to a cutting insert. The present application claims a priority based on Japanese Patent Application No. 2019-060276 filed on Mar. 27, 2019, the entire content of which is incorporated herein by reference.
Japanese Patent Laying-Open No. 2007-44779 (PTL 1) discloses a throwaway tip (cutting insert) and a milling cutter using the cutting insert.
PTL 1: Japanese Patent Laying-Open No. 2007-44779
A cutting insert according to the present disclosure includes a top surface, a bottom surface, and a side surface. The bottom surface is opposite to the top surface. The side surface is contiguous to each of the top surface and the bottom surface. A ridgeline between the top surface and the side surface includes: a nose cutting edge portion having a curved line shape, the nose cutting edge portion having a first end and a second end opposite to the first end; a major cutting edge portion contiguous to the first end; and a wiper cutting edge portion contiguous to the second end. The top surface includes: a first rake face contiguous to the wiper cutting edge portion; a second rake face contiguous to the major cutting edge portion; and a third rake face contiguous to the nose cutting edge portion and contiguous to 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 is contiguous to the major cutting edge portion.
It has been required to further improve breakage resistance in a cutting insert.
It is an object of the present disclosure to provide a cutting insert having improved breakage resistance.
According to the present disclosure, a cutting insert having improved breakage resistance can be provided.
First, embodiments of the present disclosure are listed and described.
(1) A cutting insert 100 according to the present disclosure includes a top surface 50, a bottom surface 60, and a side surface 70. Bottom surface 60 is opposite to top surface 50. Side surface 70 is contiguous to each of top surface 50 and bottom surface 60. A ridgeline 80 between top surface 50 and side surface 70 includes: a nose cutting edge portion 83 having a curved line shape, nose cutting edge portion 83 having a first end 86 and a second end 85 opposite to first end 86; a major cutting edge portion 82 contiguous to first end 86; and a wiper cutting edge portion 81 contiguous to second end 85. Top surface 50 includes: a first rake face 51 contiguous to wiper cutting edge portion 81; a second rake face 52 contiguous to major cutting edge portion 82; and a third rake face 53 contiguous to nose cutting edge portion 83 and contiguous to each of first rake face 51 and second rake face 52. A boundary line 3 between second rake face 52 and third rake face 53 is separated from first end 86 and is contiguous to major cutting edge portion 82.
(2) According to cutting insert 100 according to (1), third rake face 53 may have a first region 1 contiguous to first rake face 51 and a second region 2 contiguous to second rake face 52. In a cross section perpendicular to bottom surface 60 and intersecting each of major cutting edge portion 82 and wiper cutting edge portion 81, first region 1 may have a protruding shape and second region 2 may have a recessed shape.
(3) According to cutting insert 100 according to (1) or (2), a first distance D1 may be 1.2 or more times and 6 or less times as large as a second distance D2, first distance D1 being defined as a distance between second end 85 and a boundary point 4 between boundary line 3 and major cutting edge portion 82 in a direction parallel to bottom surface 60 and parallel to major cutting edge portion 82 when viewed in a direction perpendicular to bottom surface 60, second distance D2 being defined as a distance between second end 85 and first end 86 in the direction parallel to bottom surface 60 and parallel to major cutting edge portion 82 when viewed in the direction perpendicular to bottom surface 60.
(4) According to cutting insert 100 according to (3), in a cross section perpendicular to bottom surface 60 and inclined by 25° with respect to wiper cutting edge portion 81, third rake face 53 may be provided with a recess having an arc shape, and a curvature radius R of the recess may be 0.5 or more times as large as first distance D1.
(5) According to cutting insert 100 according to any one of (1) to (4), a rake angle of second rake face 52 may be larger than a rake angle of first rake face 51.
Next, embodiments of the present disclosure will be described in detail with reference to figures. It should be noted that in the figures described below, the same or corresponding portions are denoted by the same reference characters, and will not be described repeatedly.
First, a configuration of a cutting insert 100 according to the present embodiment will be described.
As shown in
A ridgeline 80 between top surface 50 and side surface 70 includes a major cutting edge portion 82, a nose cutting edge portion 83, a wiper cutting edge portion 81, and a sub cutting edge portion 84. Side surface 70 has a first side surface region 74, a second side surface region 76, and a third side surface region 73. First side surface region 74 is contiguous to each of wiper cutting edge portion 81 and sub cutting edge portion 84. Second side surface region 76 is contiguous to major cutting edge portion 82. Second side surface region 76 has a first side surface portion 72 and a second side surface portion 75. Third side surface region 73 is contiguous to nose cutting edge portion 83.
First side surface portion 72 is located between bottom surface 60 and second side surface portion 75. First side surface portion 72 is contiguous to, for example, each of second side surface portion 75 and third side surface region 73. Third side surface region 73 is located between first side surface region 74 and second side surface region 76. Third side surface region 73 is contiguous to each of first side surface region 74 and second side surface region 76. Third side surface region 73 is located between first side surface region 74 and first side surface portion 72. Third side surface region 73 is located between first side surface region 74 and second side surface portion 75.
One end of wiper cutting edge portion 81 is the other end (second end 85) of nose cutting edge portion 83. The other end (third end 87) of wiper cutting edge portion 81 is contiguous to sub cutting edge portion 84. When viewed in the direction perpendicular to bottom surface 60, cutting insert 100 extends along a long side direction V and a short side direction X. Major cutting edge portion 82 extends along long side direction Y. Wiper cutting edge portion 81 extends along short side direction X. The extending direction of major cutting edge portion 82 is inclined by an angle of substantially 90° with respect to the extending direction of wiper cutting edge portion 81. Sub cutting edge portion 84 is inclined to the insert mounting hole 9 side with respect to wiper cutting edge portion 81. The extending direction of sub cutting edge portion 84 is inclined by an angle of more than 0° and less than 90° with respect to the extending direction of wiper cutting edge portion 81. Sub cutting edge portion 84 is inclined with respect to each of long side direction Y and short side direction X.
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 central flat portion 55. First rake face 51 is contiguous to wiper cutting edge portion 81. First rake face 51 has a first land portion 41 and a first rake face portion 31. First land portion 41 is contiguous to wiper cutting edge portion 81. First rake face portion 31 is contiguous to first land portion 41. As shown in
Second rake face 52 is contiguous to major cutting edge portion 82. Second rake face 52 has a second land portion 42 and a second rake face portion 32. Second land portion 42 is contiguous to major cutting edge portion 82. Second rake face portion 32 is contiguous to second land portion 42. As shown in
Fourth rake face 54 is contiguous to sub cutting edge portion 84. Fourth rake face 54 has a fourth land portion 44 and a fourth rake face portion 34. Fourth land portion 44 is contiguous to sub cutting edge portion 84. Fourth rake face portion 34 is contiguous to fourth land portion 44. As shown in
Central flat portion 55 is contiguous to insert mounting hole 9. When viewed in the direction perpendicular to bottom surface 60, central flat portion 55 is located between insert mounting hole 9 and each of first rake face 51, second rake face 52, third rake face 53, and fourth rake face 54. Central flat portion 55 is contiguous to each of first rake face 51, second rake face 52, third rake face 53, and fourth rake face 54. Central flat portion 55 is provided with, for example, four recesses 61. As shown in
As shown in
First side surface region 74 is contiguous to wiper cutting edge portion 81. First side surface region 74 may be contiguous to sub cutting edge portion 84. First side surface region 74 is inclined to the insert mounting hole 9 side with respect to the plane perpendicular to bottom surface 60. The inclination angle (third inclination angle θ3) of first side surface region 74 with respect to the plane perpendicular to bottom surface 60 is, for example, more than or equal to 10° and less than or equal to 30°. First side surface region 74 is contiguous to bottom surface 60. First side surface region 74 functions as a flank face.
As shown in
Second side surface region 76 has a first side surface portion 72 and a second side surface portion 75. Second side surface portion 75 is contiguous to major cutting edge portion 82. Second side surface portion 75 is inclined to the insert mounting hole 9 side with respect to the plane perpendicular to bottom surface 60. First side surface portion 72 is contiguous to second side surface portion 75. First side surface portion 72 is located between second side surface portion 75 and bottom surface 60 in the direction perpendicular to bottom surface 60. First side surface portion 72 is inclined with respect to the plane perpendicular to bottom surface 60. The inclination angle (fifth angle θ5) of first side surface portion 72 with respect to the plane perpendicular to bottom surface 60 is larger than the inclination angle (fourth angle θ4) of second side surface portion 75 with respect to the plane perpendicular to bottom surface 60. Second side surface region 76 functions as a flank face.
As shown in
As shown in
As shown in
First region land portion 21 is contiguous to each of first land portion 41 and second region land portion 22. First region land portion 21 is located between first land portion 41 and second region land portion 22. Second region land portion 22 is contiguous to each of second land portion 42 and first region land portion 21. Second region land portion 22 is located between second land portion 42 and first region land portion 21. First straight line portion 7 is a boundary between second region rake face portion 12 and second rake face portion 32. Second straight line portion 8 is a boundary between second land portion 42 and second region land portion 22.
As shown in
In cut surface 10, first region 1 is a protrusion having an arc shape, and second region 2 is a recess having an arc shape. Curvature radius R of the recess having the arc shape may be 0.5 or more times as large as first distance D1. Curvature radius R of the recess having the arc shape may be 0.6 or more times as large as first distance D1, or may be 0.7 or more times as large as first distance D1.
Second rake face 52 is disposed at a position higher than second region 2 in the direction perpendicular to bottom surface 60. From another point of view, it can be said that the distance between bottom surface 60 and second rake face 52 is larger than the distance between bottom surface 60 and second region 2. First region 1 is disposed at a position lower than first rake face 51 in the direction perpendicular to bottom surface 60. From another point of view, it can be said that the distance between bottom surface 60 and first rake face 51 is larger than the distance between bottom surface 60 and first region 1.
Next, the following describes functions and effects of cutting insert 100 according to the present embodiment.
According to cutting insert 100 of the present embodiment, top surface 50 includes: first rake face 51 contiguous to wiper cutting edge portion 81; second rake face 52 contiguous to major cutting edge portion 82; and third rake face 53 contiguous to nose cutting edge portion 83 and contiguous to each of first rake face 51 and second rake face 52. Boundary line 3 between second rake face 52 and third rake face 53 is separated from first end 86 and is contiguous to major cutting edge portion 82. Thus, the thickness in the vicinity of nose cutting edge portion 83 can be made larger than that in cutting insert 100 in which boundary line 3 between second rake face 52 and third rake face 53 is contiguous to first end 86. Further, when viewed in a cross sectional view, second rake face 52 and third rake face 53 are smoothly connected to each other. Therefore, the magnitude of the gradient of the maximum principal stress can be reduced in a rake face. As a result, breakage resistance is improved.
Further, according to cutting insert 100 according to the present embodiment, third rake face 53 may have first region 1 contiguous to first rake face 51 and second region 2 contiguous to second rake face 52. In the cross section perpendicular to bottom surface 60 and intersecting each of major cutting edge portion 82 and wiper cutting edge portion 81, first region 1 may have a protruding shape and second region 2 may have a recessed shape. Thus, the curl diameter of swarf generated during cutting can be made small, thereby improving a swarf discharging characteristic.
Further, according to cutting insert 100 according to the present embodiment, first distance D1 may be 1.2 or more times and 6 or less times as large as second distance D2, first distance D1 being defined as the distance between second end 85 and boundary point 4 between boundary line 3 and major cutting edge portion 82 in the direction parallel to bottom surface 60 and parallel to major cutting edge portion 82 when viewed in the direction perpendicular to bottom surface 60, second distance D2 being defined as the distance between second end 85 and first end 86 in the direction parallel to bottom surface 60 and parallel to major cutting edge portion 82 when viewed in the direction perpendicular to bottom surface 60. With first distance D1 being 1.2 or more times as large as second distance D2, the breakage resistance can be improved. With first distance D1 being 6 or less times as large as second distance D2, the swarf discharging characteristic can be improved.
Further, according to cutting insert 100 according to the present embodiment, in the cross section perpendicular to bottom surface 60 and inclined by 25° with respect to wiper cutting edge portion 81, third rake face 53 may be provided with the recess having the arc shape, and curvature radius R of the recess may be 0.5 or more times as large as first distance D1. Thus, the breakage resistance can be improved.
Further, according to cutting insert 100 according to the present embodiment, the rake angle of second rake face 52 may be larger than the rake angle of first rake face 51. Thus, the swarf discharging characteristic can be improved.
Next, the following describes a simulation result of gradient of maximum principal stress in a rake face.
First, simulation models of cutting inserts 100 according to samples 1 and 2 were produced. Cutting insert 100 according to sample 1 is an example of the present disclosure and has the shape shown in
Each of the simulation models of cutting inserts 100 according to samples 1 and 2 was used to calculate the gradient of the maximum principal stress in the rake face. As simulation software, NX8.0 provided by SIEMENS was used. A load was applied to a range with a width of 0.2 mm and a height of 3 mm along major cutting edge portion 82 and first end 86. The direction of the load was perpendicular to bottom surface 60. The load was 1000 N. A feed amount per cutting edge (fz) was assumed to be 0.2 mm/tooth. A mesh size was 0.05 mm.
Table 1 shows the maximum value of the gradient of the maximum principal stress in the rake face of each of cutting inserts 100 according to samples 1 and 2. As shown in Table 1, the maximum value of the gradient of the maximum principal stress in the rake face of cutting insert 100 according to sample 1 was 732 MPa/mm. On the other hand, the maximum value of the gradient of the maximum principal stress in the rake face of cutting insert 100 according to sample 2 was 1478 MPa/mm. From the above results, it was confirmed that the gradient of the maximum principal stress in the rake face can be reduced in cutting insert 100 according to sample 1 as compared with cutting insert 100 according to sample 2.
The embodiments and examples disclosed herein are illustrative and non-restrictive in any respect. The scope of the present invention is defined by the terms of the claims, rather than the embodiments described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
1 first region; 2: second region; 3: second boundary line (boundary line); 4: boundary point; 5: first boundary line; 6: third boundary line; 7: first straight line portion; 8: second straight line portion; 9: insert mounting hole; 10: cut surface; 11: first region rake face portion; 12: second region rake face portion; 21: first region land portion; 22: second region land portion; 31: first rake face portion; 32: second rake face portion; 33: third rake face portion; 34: fourth rake face portion; 41: first land portion. 42: second land portion; 43: third land portion; 44: fourth land portion; 50: upper surface; 51: first rake face; 52: second rake face; 53: third rake face; 54: fourth rake face; 55: central flat portion; 60: bottom surface; 61: recess; 70: side surface; 72: first side surface portion; 73: third side surface region; 74: first side surface region; 75: second side surface portion; 76: second side surface region; 80: ridgeline; 81: wiper cutting edge portion; 82: major cutting edge portion; 83 nose cutting edge portion; 84: sub cutting edge portion; 85: second end; 86: first end; 87: third end; 100: cutting insert; D1: first distance; D2: second distance; R: curvature radius; X: short side direction; Y: long side direction; θ1: first rake angle; θ2: second rake angle; θ3: third inclination angle; θ4: fourth inclination angle; θ5: fifth inclination angle; θ6: sixth inclination angle.
Number | Date | Country | Kind |
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2019-060276 | Mar 2019 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2020/012971 | 3/24/2020 | WO | 00 |