Cutting Inserts and Cutting Tools

Abstract

The cutting insert includes a rake face, a flank, and a leading cutting edge. The leading cutting edge is formed by a ridge between the rake face and the flank. The flank includes a first flank portion, a second flank portion, a third flank portion, and a fourth flank portion. The third flank portion is located opposite the first flank portion. The fourth flank portion is located opposite the second flank portion. The leading cutting edge includes a first cutting edge portion. The first cutting edge portion is formed by a ridge between the rake face and the first flank portion. The first cutting edge portion is linear. In the first cutting edge portion, the angle formed by the first flank portion with respect to the rake face is greater than 89° and less than 91°. The angle formed by the second flank portion with respect to the rake face is less than 90°. The angle formed by the third flank portion with respect to the rake face is greater than 90°. The angle formed by the fourth flank portion with respect to the rake face is greater than 89° and less than 91°.

Description

[Technical Field]

[0001] The present disclosure relates to cutting inserts and cutting tools. [Background technology]

[0002] International Publication No. 2019 / 087496 (Patent Document 1) discloses a cutting insert having a rake face, a flank face, and a chamfer disposed between the rake face and the flank face. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 087496 Summary of the Invention

[0004] The cutting insert according to the present disclosure includes a rake face, a flank face, and a leading cutting edge. The leading cutting edge is formed by a ridge between the rake face and the flank face. The flank face includes a first flank portion, a second flank portion, a third flank portion, and a fourth flank portion. The third flank portion is located opposite the first flank portion. The fourth flank portion is located opposite the second flank portion. The leading cutting edge includes a first cutting edge portion. The first cutting edge portion is formed by a ridge between the rake face and the first flank portion. The first cutting edge portion is linear. In the first cutting edge portion, the angle formed by the first flank portion with respect to the rake face is greater than 89° and less than 91°. The angle formed by the second flank portion with respect to the rake face is less than 90°. The angle formed by the third flank portion with respect to the rake face is greater than 90°. The angle formed by the fourth flank portion with respect to the rake face is greater than 89° and less than 91°. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective schematic view showing the configuration of a cutting insert according to a first embodiment. [Figure 2] FIG. 2 is a schematic plan view showing the configuration of the cutting insert according to the first embodiment. [Figure 3] FIG. 3 is a perspective schematic view showing the configuration of the cutting insert according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram showing a cross section perpendicular to a tangent line of the first cutting edge portion. [Figure 5] FIG. 5 is a schematic diagram showing a cross section perpendicular to a tangent line of the second cutting edge portion. [Figure 6] FIG. 6 is a schematic diagram showing a cross section perpendicular to the tangent line of the third ridge portion. [Figure 7] FIG. 7 is a schematic diagram showing a cross section perpendicular to the tangent line of the fourth ridge portion. [Figure 8] FIG. 8 is a schematic perspective view showing the configuration of a cutting tool according to the second embodiment. [Figure 9] FIG. 9 is a partially enlarged schematic plan view showing the configuration of a cutting tool according to the second embodiment. [Figure 10] FIG. 10 is a schematic front view showing the configuration of a cutting tool according to the second embodiment. [Figure 11] FIG. 11 is a partially enlarged schematic side view showing the configuration of a cutting tool according to a second embodiment. [Figure 12] FIG. 12 is a schematic view showing a processing method using the cutting tool according to the second embodiment. [Figure 13] FIG. 13 is a perspective schematic view showing the configuration of a cutting insert according to a third embodiment. [Figure 14] FIG. 14 is a schematic plan view showing the configuration of a cutting insert according to a third embodiment. [Figure 15] FIG. 15 is a perspective schematic view showing the configuration of a cutting tool according to a fourth embodiment. [Figure 16] FIG. 16 is a partially enlarged schematic plan view showing the configuration of a cutting tool according to a fourth embodiment. [Figure 17] FIG. 17 is a schematic front view showing the configuration of a cutting tool according to a fourth embodiment. [Figure 18] FIG. 18 is a partially enlarged schematic side view showing the configuration of a cutting tool according to a fourth embodiment. [Figure 19]FIG. 19 is a schematic view showing a processing method using the cutting tool according to the fourth embodiment. [Figure 20] FIG. 20 is a schematic plan view showing measurement points on each of the holder and the cutting insert. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] When performing drawing, if the cutting resistance is large, there is a risk of chipping of the cutting edge, and the cutting insert may rotate or lift off the holder, causing the cutting insert to become misaligned with respect to the holder.

[0007] An object of the present disclosure is to provide a cutting insert with reduced slippage relative to a holder while reducing chipping. [Effects of this disclosure] According to the present disclosure, it is possible to provide a cutting insert that reduces breakage and also reduces displacement relative to a holder. [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0008] (1) A cutting insert according to the present disclosure includes a rake face, a flank face, and a leading cutting edge. The leading cutting edge is formed by a ridge between the rake face and the flank face. The flank face includes a first flank portion, a second flank portion, a third flank portion, and a fourth flank portion. The third flank portion is located opposite the first flank portion. The fourth flank portion is located opposite the second flank portion. The leading cutting edge includes a first cutting edge portion. The first cutting edge portion is formed by a ridge between the rake face and the first flank portion. The first cutting edge portion is linear. In the first cutting edge portion, the angle formed by the first flank portion with respect to the rake face is greater than 89° and less than 91°. The angle formed by the second flank portion with respect to the rake face is less than 90°. The angle formed by the third flank portion with respect to the rake face is greater than 90°. The angle of the fourth flank portion relative to the rake face is greater than 89° and less than 91°. This improves the strength of the cutting insert, reducing damage to the leading cutting edge when machining a workpiece using a cutting tool equipped with the cutting insert. Furthermore, rotation of the cutting insert and lift-up from the holder are suppressed, reducing misalignment relative to the holder.

[0009] (2) According to the cutting insert of (1) above, the leading cutting edge may include a corner cutting edge portion, a draft edge portion, and a second cutting edge portion. The second cutting edge portion may be continuous with the corner cutting edge portion. The second cutting edge portion may be formed by a ridge between the rake face and the second flank portion. The corner cutting edge portion may be curved. The draft edge portion may be disposed between the first cutting edge portion and the corner cutting edge portion. In this way, the finished surface roughness can be significantly improved during cutting. Therefore, a stable and good surface roughness can be obtained even in high-efficiency cutting.

[0010] (3) The cutting insert according to (1) or (2) above may include a first bottom surface located opposite the rake face. The angle of the fourth flank portion relative to the first bottom surface may be the same as the angle of the first flank portion relative to the rake face. The angle of the third flank portion relative to the first bottom surface may be the same as the angle of the second flank portion relative to the rake face. The angle of the second flank portion relative to the first bottom surface may be the same as the angle of the third flank portion relative to the rake face. The angle of the first flank portion relative to the first bottom surface may be the same as the angle of the fourth flank portion relative to the rake face. In this way, the cutting insert can be used upside down.

[0011] (4) The cutting insert according to (3) above may include a rear cutting edge formed by a ridge line between the first bottom surface and the flank. In this way, the workpiece can be cut using not only the blade member forming the front cutting edge but also the blade member forming the rear cutting edge, thereby providing an economical cutting insert.

[0012] (5) A cutting tool according to the present disclosure may include the cutting insert according to (2) above and a holder. The holder may be provided with a recess for restraining the cutting insert. The cutting insert may include a first bottom surface located opposite the rake face. The recess may have a second bottom surface opposite the first bottom surface.

[0013] (6) According to the cutting tool of (5) above, a plane parallel to the longitudinal direction of the holder and passing through the corner cutting edge portion may be used as the reference plane. When viewed from the longitudinal direction, the first cutting edge portion may be disposed between the reference plane and the second bottom surface. When viewed from a direction perpendicular to the longitudinal direction, the second cutting edge portion may be disposed farther from the second bottom surface than the reference plane. In this way, the cutting tool can be used to perform drawing on the outer peripheral surface of a workpiece.

[0014] (7) According to the cutting tool of (5) above, a plane parallel to the longitudinal direction of the holder and passing through the corner cutting edge portion may be used as the reference plane. When viewed from a direction perpendicular to the longitudinal direction, the first cutting edge portion may be disposed between the reference plane and the second bottom surface. When viewed from the longitudinal direction, the second cutting edge portion may be disposed farther from the second bottom surface than the reference plane. In this way, the cutting tool can be used to perform drawing on the end face of the workpiece.

[0015] (8) According to the cutting tool of any one of (5) to (7) above, the recess may have a first constraining surface and a second constraining surface. The first constraining surface may contact the third flank portion. The second constraining surface may contact the fourth flank portion. The first constraining surface may be along the third flank portion. The second constraining surface may be along the fourth flank portion. In this way, rotation of the cutting insert and lifting from the holder are suppressed, and misalignment with respect to the holder is reduced.

[0016] (9) According to the cutting tool of any one of (5) to (8), the cutting insert may include a blade member and a base metal. The blade member may be attached to the base metal by a brazing material. The blade member may be made of a cBN-based sintered body. The base metal may be made of a cemented carbide alloy.

[0017] (10) According to the cutting tool of any one of (5) to (9) above, the holder may be made of steel.

[0018] (11) The cutting tool according to any one of (5) to (10) above may include a shim. The shim may be disposed between the second bottom surface and the cutting insert. The shim may be made of cemented carbide.

[0019] (12) According to the cutting tool of any one of (5) to (11) above, the cutting insert may be for turning. [Details of the embodiments of the present disclosure] A specific example of a cutting insert according to an embodiment of the present disclosure will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

[0020] (First embodiment) <Cutting insert configuration> FIG. 1 is a perspective schematic diagram showing the configuration of a cutting insert 100 according to the first embodiment. As shown in FIG. 1, the cutting insert 100 according to the first embodiment has two blade members 1a, 1b and a base metal 2. The blade members 1a, 1b are attached to the base metal 2. Each of the blade members 1a, 1b is involved in cutting. The shape of the base metal 2 in a plan view is not particularly limited, but may be, for example, a rhombus. The blade members 1a, 1b are joined to acute corners of the base metal 2. The base metal 2 is made of, for example, cemented carbide or cermet. The cutting insert 100 according to the first embodiment is formed by joining the blade members 1a, 1b to acute corners of the base metal 2, but the entire cutting insert 100 may be formed of blade members.

[0021] A counterbore 4a is formed by partially recessing part of the upper surface (second rake face portion 12) at an acute-angle corner of the base metal 2. The blade member 1a is attached to the base metal 2 at the counterbore 4a by a joining means such as brazing material.

[0022] The blade members 1a and 1b may be made of a cBN-based sintered body, or may be made of any of a diamond-based sintered body, ceramics, cermet, or cemented carbide. The cBN-based sintered body is a sintered body containing cBN (cubic boron nitride) in a volume ratio of 10 to 100%. The diamond-based sintered body is a sintered body containing diamond in a volume ratio of 10 to 100%. The ceramic may be, for example, alumina (Al2O3), silicon nitride (Si3N4), or titanium carbide (TiC). The cermet may be, for example, a nitride-based cermet or a carbide-based cermet.

[0023] The cutting insert 100 according to the first embodiment includes a rake face 10, a flank face 20, a first bottom face 30, and a leading cutting edge 40. The first bottom face 30 is located opposite the rake face 10. The flank face 20 connects the rake face 10 and the first bottom face 30. The leading cutting edge 40 is formed by a ridge line 50 between the rake face 10 and the flank face 20. The leading cutting edge 40 is a part of the ridge line 50.

[0024] The ridge 50 includes the front cutting edge 40, a first ridge portion 51, a second ridge portion 52, a third ridge portion 53, and a fourth ridge portion 54. The front cutting edge 40 includes the first cutting edge portion 41, the second cutting edge portion 42, a corner cutting edge portion 43, and a scraping edge portion 44. The front cutting edge 40 is made up of the blade member 1a. The first ridge portion 51, the second ridge portion 52, the third ridge portion 53, and the fourth ridge portion 54 are made up of the base metal 2.

[0025] As shown in FIG. 1 , the first cutting edge portion 41 connects the flattening edge portion 44 and the first ridge portion 51. The second cutting edge portion 42 connects the corner cutting edge portion 43 and the second ridge portion 52. The corner cutting edge portion 43 connects the second cutting edge portion 42 and the flattening edge portion 44. The flattening edge portion 44 connects the first cutting edge portion 41 and the corner cutting edge portion 43. The flattening edge portion 44 is disposed between the first cutting edge portion 41 and the corner cutting edge portion 43.

[0026] The first ridge portion 51 connects the first cutting edge portion 41 and the fourth ridge portion 54. The second ridge portion 52 connects the second cutting edge portion 42 and the third ridge portion 53. The third ridge portion 53 connects the second ridge portion 52 and the fourth ridge portion 54. The fourth ridge portion 54 connects the first ridge portion 51 and the third ridge portion 53.

[0027] The rake face 10 has a first rake face portion 11 and a second rake face portion 12. The first rake face portion 11 is formed of a blade member 1a. The second rake face portion 12 is formed of a base metal 2. A through hole 5 is formed in the second rake face portion 12.

[0028] The flank 20 includes a first flank portion 21, a second flank portion 22, a third flank portion 23, a fourth flank portion 24, a corner flank portion 25, and a scraper flank portion 26. The third flank portion 23 is located opposite the first flank portion 21. The fourth flank portion 24 is located opposite the second flank portion 22.

[0029] The first flank portion 21 includes a first cutting edge flank portion 21a and a first base flank portion 21b. The second flank portion 22 includes a second cutting edge flank portion 22a and a second base flank portion 22b. The first cutting edge flank portion 21a, the second cutting edge flank portion 22a, the corner flank portion 25, and the scraper flank portion 26 are formed from the blade member 1a. The first base flank portion 21b, the second base flank portion 22b, the third flank portion 23, and the fourth flank portion 24 are formed from the base 2.

[0030] The first cutting edge portion 41 is formed by a ridgeline 50 between the first rake face portion 11 of the rake face 10 and the first cutting edge flank portion 21a of the first flank portion 21. The second cutting edge portion 42 is formed by a ridgeline 50 between the first rake face portion 11 of the rake face 10 and the second cutting edge flank portion 22a of the second flank portion 22. The corner cutting edge portion 43 is formed by a ridgeline 50 between the first rake face portion 11 of the rake face 10 and the corner flank portion 25. The scraping edge portion 44 is formed by a ridgeline 50 between the first rake face portion 11 of the rake face 10 and the scraping flank portion 26.

[0031] The first ridge portion 51 is formed by the ridge line 50 between the second rake face portion 12 of the rake face 10 and the first base flank portion 21b of the first flank portion 21. The second ridge portion 52 is formed by the ridge line 50 between the second rake face portion 12 of the rake face 10 and the second base flank portion 22b of the second flank portion 22. The third ridge portion 53 is formed by the ridge line 50 between the second rake face portion 12 of the rake face 10 and the third flank portion 23. The fourth ridge portion 54 is formed by the ridge line 50 between the second rake face portion 12 of the rake face 10 and the fourth flank portion 24.

[0032] The first cutting edge flank portion 21a is connected to the roughened flank portion 26 and the first base flank portion 21b. The roughened flank portion 26 is connected to the first cutting edge flank portion 21a and the corner flank portion 25. The corner flank portion 25 is connected to the roughened flank portion 26 and the second cutting edge flank portion 22a. The second cutting edge flank portion 22a is connected to the corner flank portion 25 and the second base flank portion 22b. The third flank portion 23 is connected to the second base flank portion 22b and the fourth flank portion 24. The fourth flank portion 24 is connected to the third flank portion 23 and the first base flank portion 21b.

[0033] Fig. 2 is a schematic plan view showing the configuration of the cutting insert 100 according to the first embodiment. The schematic plan view shown in Fig. 2 shows the rake face 10 as viewed along a line perpendicular to the rake face 10.

[0034] As shown in Figure 2, the corner cutting edge portion 43 is curved when viewed along a line perpendicular to the rake face 10. The corner cutting edge portion 43 is curved so as to be convex outward. When viewed along a line perpendicular to the rake face 10, the radius of curvature of the corner cutting edge portion 43 is 0.2 mm or more and 2.4 mm or less. The radius of curvature of the corner cutting edge portion 43 may be 0.3 mm or more and 2.2 mm or less, 0.4 mm or more and 2.0 mm or less, or 0.6 mm or more and 1.8 mm or less.

[0035] As shown in Figure 2, the shape of the scraping edge 44 is linear when viewed along a line perpendicular to the rake face 10. The shape of the scraping edge 44 may be curved when viewed along a line perpendicular to the rake face 10. When the shape of the scraping edge 44 is curved, the radius of curvature of the scraping edge 44 may be 10 mm or more and 100 mm or less, 20 mm or more and 90 mm or less, or 30 mm or more and 80 mm or less when viewed along a line perpendicular to the rake face 10. On the other hand, if the radius of curvature of the scraping edge 44 is less than 5 mm, the finished surface roughness will not be significantly improved.

[0036] 2, the first cutting edge portion 41 and the second cutting edge portion 42 each have a linear shape when viewed along a line perpendicular to the rake face 10. The length of the first cutting edge portion 41 is greater than the length of the second cutting edge portion 42. The length of the first cutting edge portion 41 may be 1.5 times or more, or may be two times or more, the length of the second cutting edge portion 42.

[0037] 2, the first ridgeline portion 51, the second ridgeline portion 52, the third ridgeline portion 53, and the fourth ridgeline portion 54 are each linear. The length of the first ridgeline portion 51 is smaller than the length of the second ridgeline portion 52. The length of the third ridgeline portion 53 is the same as the length of the fourth ridgeline portion 54. The length of the second ridgeline portion 52 is smaller than the length of the third ridgeline portion 53 and the length of the fourth ridgeline portion 54.

[0038] A through hole 5 is formed in the second rake face portion 12. The through hole 5 passes through the base metal 2. The through hole 5 opens to both the rake face 10 and the first bottom surface 30.

[0039] FIG. 3 is a perspective schematic diagram showing the configuration of the cutting insert 100 according to the first embodiment. The perspective schematic diagram shown in FIG. 3 shows the third flank portion 23 and the fourth flank portion 24 as viewed from the opposite side of the blade member 1a as viewed from the base metal 2. As shown in FIG. 3, a counterbore portion 4b, in which part of the lower surface (first bottom surface 30) is partially recessed, may be formed at a position opposite to the counterbore portion 4a (acute-angle corner portion of the base metal 2) where the blade member 1a is disposed. The blade member 1b is disposed in the counterbore portion 4b. The blade member 1b is attached to the base metal 2 at the counterbore portion 4b by a joining means such as brazing material.

[0040] The blade member 1b includes the same configuration as the blade member 1a. Specifically, the cutting insert 100 according to the first embodiment includes a rear cutting edge 60. The rear cutting edge 60 is formed from the blade member 1b. The rear cutting edge 60 includes a first cutting edge portion 61, a second cutting edge portion 62, a corner cutting edge portion 63, and a scraping edge portion 64. The rear cutting edge 60 is formed by the ridge line between the first bottom surface 30 and the flank surface 20. The rear cutting edge 60 is part of the ridge line between the first bottom surface 30 and the flank surface 20.

[0041] The blade member 1b may be attached to the base metal 2 so that the cutting insert 100 is mirror-symmetric. Specifically, when viewed along a straight line perpendicular to the rake face 10, a line that is perpendicular to a line passing through the pair of acute-angle corner portions and that passes through the center of the through hole 5 is defined as line segment A (see FIG. 2). When viewed along the straight line perpendicular to the rake face 10, the blade member 1a disposed in the counterbore portion 4a and the blade member 1b disposed in the counterbore portion 4b are arranged in mirror symmetry with respect to line segment A. In this way, the workpiece 300 can be cut using not only the blade member 1a constituting the front cutting edge 40 but also the blade member 1b constituting the rear cutting edge 60. As a result, an economical cutting insert 100 can be attached to the holder 101.

[0042] The cutting insert 100 according to the first embodiment has two blade members (corners), but the number may be one. In other words, the blade member 1b may not be arranged in the counterbore portion 4b, and the blade member 1a may be arranged only in the counterbore portion 4a.

[0043] Fig. 4 is a schematic diagram showing a cross section perpendicular to a tangent line of the first cutting edge portion 41. As shown in Fig. 4, the first flank portion 21 is aligned along a direction perpendicular to the rake face 10. Specifically, in the first cutting edge portion 41, the angle (first angle θ1) formed by the first flank portion 21 with respect to the rake face 10 is 90°. In the first cutting edge portion 41, the angle formed by the first flank portion 21 with respect to the rake face 10 may be greater than 89° and less than 91°, or may be 89.5° or greater and 90.5° or less.

[0044] In the first flank portion 21, the first cutting edge flank portion 21a and the first base flank portion 21b are arranged on the same plane. Therefore, in the first ridge portion 51, the angle that the first flank portion 21 makes with respect to the rake face 10 is 90°.

[0045] Fig. 5 is a schematic diagram showing a cross section perpendicular to a tangent line of the second cutting edge portion 42. As shown in Fig. 5, the second flank portion 22 is inclined inward with respect to a plane perpendicular to the rake face 10. Specifically, in the second cutting edge portion 42, the angle (second angle θ2) that the second flank portion 22 makes with respect to the rake face 10 is less than 90°. In the second cutting edge portion 42, the angle that the second flank portion 22 makes with respect to the rake face 10 may be 85° or less, or may be 80° or less.

[0046] The second cutting edge flank 22a and the second base flank 22b are arranged on the same plane in the second flank 22. Therefore, at the second ridge 52, the angle (first angle θ1) that the second flank 21 makes with respect to the rake face 10 is less than 90°.

[0047] FIG. 6 is a schematic diagram showing a cross section perpendicular to the tangent line of the third ridge portion 53. As shown in FIG. 6, the third flank portion 23 is inclined outward with respect to a plane perpendicular to the rake face 10. Specifically, the angle (third angle θ3) formed by the third flank portion 23 with respect to the rake face 10 is greater than 90°. The angle formed by the third flank portion 23 with respect to the rake face 10 may be 95° or greater, or may be 100° or greater. The second angle θ2 and the third angle θ3 may be determined so that the value obtained by adding the second angle θ2 to the third angle θ3 is 180°.

[0048] Fig. 7 is a schematic diagram showing a cross section perpendicular to the tangent line of the fourth ridge portion 54. As shown in Fig. 7, the fourth flank portion 24 extends along a direction perpendicular to the rake face 10. Specifically, the angle (fourth angle θ4) formed by the fourth flank portion 24 with respect to the rake face 10 is 90°. The angle formed by the fourth flank portion 24 with respect to the rake face 10 may be greater than 89° and less than 91°, or may be 89.5° or greater and 90.5° or less.

[0049] The cutting insert 100 according to the first embodiment is configured with mirror symmetry. From a different perspective, the fourth flank portion 24 as viewed from the first bottom surface 30 corresponds to the first flank portion 21 as viewed from the rake face 10. That is, the angle of the fourth flank 24 relative to the first bottom surface 30 is the same as the first angle θ1 (the angle of the first flank portion 21 relative to the rake face 10). The third flank portion 23 as viewed from the first bottom surface 30 corresponds to the second flank portion 22 as viewed from the rake face 10. That is, the angle of the third flank 23 relative to the first bottom surface 30 is the same as the second angle θ2 (the angle of the second flank portion 22 relative to the rake face 10). The second flank portion 22 as viewed from the first bottom surface 30 corresponds to the third flank portion 23 as viewed from the rake face 10. That is, the angle that the second flank 22 makes with respect to the first bottom surface 30 is the same as the third angle θ3 (the angle that the third flank portion 23 makes with respect to the rake face 10). The first flank portion 21 as viewed from the first bottom surface 30 corresponds to the fourth flank portion 24 as viewed from the rake face 10. That is, the angle that the first flank 21 makes with respect to the first bottom surface 30 is the same as the fourth angle θ4 (the angle that the fourth flank portion 24 makes with respect to the rake face 10).

[0050] (Second embodiment) <Cutting tool configuration> Next, a cutting tool 200 according to a second embodiment will be described.

[0051] FIG. 8 is a perspective schematic view showing the configuration of a cutting tool 200 according to the second embodiment. The cutting tool 200 according to the second embodiment includes the cutting insert 100 according to the first embodiment, a holder 101, a base plate 102, a pressing member 110, and a fastening screw 120. The holder 101 may be cylindrical or rectangular. The holder 101 is attached to a turret of a machine tool. The holder 101 may be made of a steel material such as chromium-molybdenum steel or die steel. The base plate 102 may be made of cemented carbide.

[0052] As shown in Figure 8, when the holder 101 is rectangular, the holder 101 has a first side surface 101a, a second side surface 101b, a third side surface 101c, a fourth side surface 101d, a first end surface 101e, and a second end surface 101f. The direction perpendicular to the first end surface 101e is the X direction. The direction perpendicular to the first side surface 101a is the Y direction. The direction perpendicular to the X direction and the Y direction is the Z direction. The longitudinal direction of the holder 101 is the X direction. The second end surface 101f is located opposite the first end surface 101e in the longitudinal direction (X direction) of the holder 101.

[0053] The first side surface 101a has a first upper surface region 101a1 and a second upper surface region 101a2. When viewed from the third side surface 101c, the second upper surface region 101a2 is disposed at a position farther in the Y direction than the first upper surface region 101a1. The second upper surface region 101a2 is continuous with the second end surface 101f.

[0054] The second side surface 101b has a first side surface region 101b1 and a second side surface region 101b2. When viewed from the fourth side surface 101d, the second side surface region 101b2 is located farther in the Z direction than the first side surface region 101b1. The second side surface region 101b2 is continuous with the second end surface 101f.

[0055] A recess 103 that restrains the cutting insert 100 is provided at the boundary between the second end surface 101f, the second upper surface region 101a2, and the second side surface region 101b2. The cutting insert 100 and the base plate 102 are arranged in the recess 103. The cutting insert 100 is arranged in a stack on the base plate 102.

[0056] FIG. 9 is a partially enlarged schematic plan view showing the configuration of a cutting tool 200 according to the second embodiment. The partially enlarged schematic plan view shown in FIG. 9 shows the cutting insert 100 viewed along a line (Y direction) perpendicular to the first side surface 101a. The cutting insert 100 is attached to the holder 101 using a pressing member 110. The pressing member 110 has a main body portion 112 and an insertion portion 111. The insertion portion 111 is inserted into the through hole 5 of the cutting insert 100. A mounting hole 113 is formed in the main body portion 112. A fastening screw 120 is inserted into the mounting hole 113. In this way, the pressing member 110 is fixed to the holder 101.

[0057] The first flank portion 21 is disposed along the second end face 101f. That is, the first cutting edge portion 41 is disposed along the second end face 101f. The second flank portion 22 is disposed along the second side surface region 101b2. That is, the second cutting edge portion 42 is disposed along the second side surface region 101b2.

[0058] Fig. 10 is a schematic front view showing the configuration of a cutting tool 200 according to a second embodiment. The schematic front view shown in Fig. 10 shows the cutting insert 100 viewed along the longitudinal direction (X direction) of the holder 101. Fig. 11 is a partially enlarged schematic side view showing the configuration of the cutting tool 200 according to the second embodiment. The partially enlarged schematic side view shown in Fig. 11 shows the cutting insert 100 viewed along the Z direction.

[0059] The recess 103 has a second bottom surface 103a, a first constraining surface 103b (see FIG. 11), and a second constraining surface 103c (see FIG. 10). The recess 103 is composed of the second bottom surface 103a, the first constraining surface 103b, and the second constraining surface 103c. The second bottom surface 103a is a surface facing the first bottom surface 30. The first constraining surface 103b is a surface that contacts the third relief surface portion 23. The first constraining surface 103b is continuous with the second upper surface region 101a2, the second side surface region 101b2, the second bottom surface 103a, and the second constraining surface 103c. The second constraining surface 103c is a surface that contacts the fourth relief surface portion 24. The second constraining surface 103c is continuous with the second upper surface region 101a2, the second end surface 101f, the second bottom surface 103a, and the second constraining surface 103c.

[0060] 10 and 11, the cutting insert 100 is disposed in the recess 103 so that the first bottom surface 30 faces the second bottom surface 103a. A base plate 102 may be disposed between the second bottom surface 103a and the first bottom surface 30.

[0061] 11, the cutting insert 100 is disposed in the recess 103 so that the third flank portion 23 faces the first constraining surface 103b. That is, when the cutting insert 100 is disposed in the recess 103, the first constraining surface 103b is along the third flank portion 23. The angle (third angle θ3) formed by the third flank portion 23 with respect to the rake face 10 exceeds 90°. Therefore, the angle formed by the first constraining surface 103b with respect to the second upper surface region 101a2 may be less than 90°.

[0062] As shown in FIG. 10 , the cutting insert 100 is disposed in the recess 103 so that the fourth flank portion 24 faces the second constraining surface 103c. That is, when the cutting insert 100 is disposed in the recess 103, the second constraining surface 103c is aligned with the fourth flank portion 24. The angle (fourth angle θ4) formed by the third flank portion 23 with respect to the rake face 10 is greater than 89° and less than 91°. Therefore, the angle formed by the second constraining surface 103c with respect to the second upper surface region 101a2 may be greater than 89° and less than 91°. When the fourth angle θ4 is 90°, the angle formed by the second constraining surface 103c with respect to the second upper surface region 101a2 may be 90°.

[0063] As shown in FIGS. 10 and 11 , a plane parallel to the longitudinal direction (X direction) of the holder 101 and passing through the corner cutting edge portion 43 is defined as a reference plane A1. The reference plane A1 may be a plane perpendicular to the first end face 101e. As shown in FIG. 10 , the first cutting edge portion 41 is inclined inward when viewed from the X direction. From a different perspective, when the cutting insert 100 is viewed from the longitudinal direction (X direction), the first cutting edge portion 41 is disposed between the reference plane A1 and the second bottom surface 103a in the Y direction. When viewed from the X direction, the angle (fifth angle θ5) formed by the first cutting edge portion 41 with respect to the reference plane A1 may be 5° or more, 7° or more, or 10° or more.

[0064] 11, the second cutting edge portion 42 is inclined outward when viewed from the Z direction. From a different perspective, when the cutting insert 100 is viewed from a direction (Z direction) perpendicular to the longitudinal direction (X direction), the second cutting edge portion 42 is disposed at a position farther in the Y direction than the reference plane A1 when viewed from the second bottom surface 103a. When viewed from the Z direction, the angle (sixth angle θ6) formed by the second cutting edge portion 42 with respect to the reference plane A1 may be 5° or more, 7° or more, or 10° or more.

[0065] Next, a description will be given of a machining method using the cutting tool 200 according to the second embodiment. Fig. 12 is a schematic diagram showing the machining method using the cutting tool 200 according to the second embodiment.

[0066] The cutting tool 200 equipped with the cutting insert 100 according to the first embodiment is capable of drawing the outer peripheral surface 301 of a workpiece 300. The workpiece 300 has an outer peripheral surface 301. The drawing according to the second embodiment is performed while moving the cutting insert 100 in a first feed direction D1. The first feed direction D1 is a direction toward the -Z direction. In the drawing, the workpiece 300 is machined using the first cutting edge portion 41. The outer peripheral surface 301 is parallel to the rotation axis X1 of the workpiece 300. In other words, the first feed direction D1 is parallel to the rotation axis X1 of the workpiece 300. The workpiece 300 rotates in a rotation direction R1 around the rotation axis X1. In this manner, the cutting insert 100 may be used for turning.

[0067] The first angle θ1 is 90°. Therefore, the strength of the cutting insert 100 during drawing is sufficiently ensured. In other words, even when a workpiece 300 is machined using a cutting tool 200 equipped with the cutting insert 100, damage to the leading cutting edge 40 as a cutting edge is reduced. The third angle θ3 is greater than 90°. Therefore, even if the cutting resistance in the Y direction increases during drawing, the cutting insert 100 does not lift off the holder 101. The fourth angle θ4 is 90°. In other words, the fourth flank portion 24 is aligned perpendicular to the rotation direction of the cutting insert 100 as viewed from the Y direction. Therefore, even if the cutting resistance increases during drawing, the cutting insert 100 does not rotate within the reference plane A1. In this way, deviation of the cutting insert 100 from the holder 101 is reduced. The second angle θ2 is less than 90°. Therefore, the second flank portion 22 is inclined inward with respect to a plane perpendicular to the rake face 10. As a result, the second flank portion 22 does not interfere with the end face 302 (see FIG. 19 ) of the workpiece 300 when machining the end face 302. Also, when viewed from the X direction, the first cutting edge portion 41 is inclined inward. Therefore, the first cutting edge portion 41 can be brought into contact with the workpiece 300 to perform efficient drawing machining.

[0068] The cutting insert 100 may be used to perform press machining on the outer peripheral surface 301 of the workpiece 300. The press machining is performed by moving the cutting insert 100 in the direction opposite to the first feed direction D1 (toward the Z direction). In the press machining, the workpiece 300 is machined using the second cutting edge portion 42. When viewed from the Z direction, the second cutting edge portion 42 is inclined outward. Therefore, the second cutting edge portion 42 can be brought into contact with the workpiece 300 to perform the press machining efficiently.

[0069] (Third embodiment) <Cutting tool configuration> Next, a cutting insert 100 according to a third embodiment will be described. The cutting insert 100 according to the third embodiment differs from the cutting insert 100 according to the first embodiment mainly in that the cutting insert 100 according to the third embodiment is configured to be mirror symmetrical with respect to the cutting insert 100 according to the first embodiment, and is similar to the cutting insert 100 according to the first embodiment in other respects. The following description will focus on the configuration that differs from the cutting insert 100 according to the first embodiment.

[0070] Fig. 13 is a schematic perspective view showing the configuration of a cutting insert 100 according to a third embodiment. The schematic perspective view shown in Fig. 13 shows a state in which it is mirror symmetrical with respect to the schematic perspective view of the cutting insert 100 shown in Fig. 1. Fig. 14 is a schematic plan view showing the configuration of the cutting insert 100 according to the third embodiment. The schematic plan view shown in Fig. 14 shows a state in which it is mirror symmetrical with respect to the schematic plan view of the cutting insert 100 shown in Fig. 2.

[0071] Specifically, the cutting insert 100 of the third embodiment is configured to be a plane passing through a pair of acute-angle corner portions when viewed along a straight line perpendicular to the cutting face 10 in the cutting insert 100 of the first embodiment, and is mirror-symmetrical with respect to a plane passing through the center of the through hole 5.

[0072] The magnitude relationship between the first angle θ1, the second angle θ2, the third angle θ3, and the fourth angle θ4 in the third embodiment is the same as the magnitude relationship between the first angle θ1, the second angle θ2, the third angle θ3, and the fourth angle θ4 in the first embodiment.

[0073] (Fourth embodiment) <Cutting tool configuration> Next, a cutting tool 200 according to a fourth embodiment will be described. The cutting tool 200 according to the fourth embodiment differs from the cutting tool 200 according to the second embodiment mainly in that the cutting insert 100 according to the third embodiment is attached to the holder 101, but is otherwise similar to the cutting tool 200 according to the second embodiment. The following description will focus on the configurations that differ from the cutting tool 200 according to the fourth embodiment.

[0074] 15 is a perspective schematic view showing the configuration of a cutting tool 200 according to the fourth embodiment. The cutting tool 200 according to the fourth embodiment has the cutting insert 100 according to the second embodiment, a holder 101, a base plate 102, a pressing member 110, and a fastening screw 120.

[0075] Fig. 16 is a partially enlarged schematic plan view showing the configuration of a cutting tool 200 according to the fourth embodiment. The partially enlarged schematic plan view shown in Fig. 16 shows the cutting insert 100 viewed along a straight line (Y direction) perpendicular to the first side surface 101a.

[0076] 16, the first flank portion 21 is disposed along the second side surface region 101b2. That is, the first cutting edge portion 41 is disposed along the second side surface region 101b2. The second flank portion 22 is disposed along the second end surface 101f. That is, the second cutting edge portion 42 is disposed along the second end surface 101f.

[0077] Fig. 17 is a schematic front view showing the configuration of a cutting tool 200 according to a fourth embodiment. The schematic front view shown in Fig. 17 shows the cutting insert 100 viewed along the longitudinal direction (X direction) of the holder 101. Fig. 18 is a partially enlarged schematic side view showing the configuration of the cutting tool 200 according to the fourth embodiment. The partially enlarged schematic side view shown in Fig. 18 shows the cutting insert 100 viewed along the Z direction.

[0078] 18, in the cutting tool 200 according to the fourth embodiment, the first constraining surface 103b is a surface that contacts the fourth flank portion 24. As shown in Fig. 17, in the cutting tool 200 according to the fourth embodiment, the second constraining surface 103c is a surface that contacts the third flank portion 23.

[0079] That is, as shown in FIG. 18 , the cutting insert 100 is disposed in the recess 103 so that the fourth flank portion 24 faces the first constraining surface 103b. When the cutting insert 100 is disposed in the recess 103, the first constraining surface 103b is aligned with the fourth flank portion 24. The angle (fourth angle θ4) formed by the fourth flank portion 24 with respect to the rake face 10 is greater than 89° and less than 91°. Therefore, the angle formed by the first constraining surface 103b with respect to the second upper surface region 101a2 may be greater than 89° and less than 91°. When the fourth angle θ4 is 90°, the angle formed by the first constraining surface 103b with respect to the second upper surface region 101a2 may be 90°.

[0080] 17, the cutting insert 100 is disposed in the recess 103 so that the third flank portion 23 faces the second constraining surface 103c. That is, when the cutting insert 100 is disposed in the recess 103, the second constraining surface 103c is along the third flank portion 23. The angle (third angle θ3) formed by the third flank portion 23 with respect to the rake face 10 exceeds 90°. Therefore, the angle formed by the second constraining surface 103c with respect to the second upper surface region 101a2 may be less than 90°.

[0081] As shown in FIGS. 17 and 18, a plane parallel to the longitudinal direction (X direction) of the holder 101 and passing through the corner cutting edge portion 43 is defined as a reference plane A2. The reference plane A2 may be perpendicular to the first end face 101e. As shown in FIG. 18, the first cutting edge portion 41 is inclined inward when viewed from the Z direction. From a different perspective, when the cutting insert 100 is viewed along a direction (Z direction) perpendicular to the longitudinal direction (X direction), the first cutting edge portion 41 is disposed between the reference plane A2 and the second bottom surface 103a in the Y direction. When viewed from the Z direction, the angle (seventh angle θ7) formed by the first cutting edge portion 41 with respect to the reference plane A2 may be 5° or more, 7° or more, or 10° or more.

[0082] 17, the second cutting edge portion 42 is inclined outward when viewed from the X direction. From a different perspective, when the cutting insert 100 is viewed along the longitudinal direction (X direction), the second cutting edge portion 42 is disposed at a position farther in the Y direction than the reference plane A2 when viewed from the second bottom surface 103a. When viewed from the X direction, the angle (eighth angle θ8) formed by the second cutting edge portion 42 with respect to the reference plane A2 may be 5° or more, 7° or more, or 10° or more.

[0083] Next, a description will be given of a machining method using the cutting tool 200 according to the fourth embodiment. Figure 19 is a schematic diagram showing the machining method using the cutting tool 200 according to the fourth embodiment.

[0084] The cutting tool 200 equipped with the cutting insert 100 according to the fourth embodiment is capable of drawing the end surface 302 of the workpiece 300. The workpiece 300 has an end surface 302. The drawing according to the fourth embodiment is performed while moving the cutting insert 100 in a second feed direction D2. The second feed direction D2 is a direction toward the −X direction. In the drawing, the workpiece 300 is machined using the first cutting edge portion 41. The end surface 302 is perpendicular to the rotation axis X2 of the workpiece 300. Therefore, the second feed direction D2 is perpendicular to the rotation axis X2 of the workpiece 300. The workpiece 300 rotates around the rotation axis X2 in a rotation direction R2. In this manner, the cutting insert 100 may be configured to be capable of drawing the end surface 302 of the workpiece 300.

[0085] Next, the effects of the cutting insert 100 and the cutting tool 200 according to this embodiment will be described.

[0086] The cutting insert 100 according to this embodiment includes a rake face 10, a flank 20, and a leading cutting edge 40. The leading cutting edge 40 is defined by a ridge line 50 between the rake face 10 and the flank 20. The flank 20 includes a first flank portion 21, a second flank portion 22, a third flank portion 23, and a fourth flank portion 24. The third flank portion 23 is located opposite the first flank portion 21. The fourth flank portion 24 is located opposite the second flank portion 22. The leading cutting edge 40 includes a first cutting edge portion 41. The first cutting edge portion 41 is defined by the ridge line 50 between the rake face 10 and the first flank portion 21. The first cutting edge portion 41 is linear. In the first cutting edge portion 41, the angle (first angle θ1) of the first flank portion 21 relative to the rake face 10 is greater than 89° and less than 91°. The angle (second angle θ2) of the second flank portion 22 relative to the rake face 10 is less than 90°. The angle (third angle θ3) of the third flank portion 23 relative to the rake face 10 is greater than 90°. The angle (fourth angle θ4) of the fourth flank portion 24 relative to the rake face 10 is greater than 89° and less than 91°. This improves the strength of the cutting insert 100, thereby reducing damage to the leading cutting edge 40 as a cutting edge even when a cutting tool 200 equipped with the cutting insert 100 is used to machine a workpiece 300. Furthermore, rotation of the cutting insert 100 and lift-up from the holder 101 are suppressed, reducing misalignment relative to the holder 101.

[0087] According to the cutting insert 100 of this embodiment, the leading cutting edge 40 includes a corner cutting edge portion 43, a draft edge portion 44, and a second cutting edge portion 42. The second cutting edge portion 42 is continuous with the corner cutting edge portion 43. The second cutting edge portion 42 is formed by a ridge line 50 between the rake face 10 and the second flank portion 22. The corner cutting edge portion 43 is curved. The draft edge portion 44 is disposed between the first cutting edge portion 41 and the corner cutting edge portion 43. In this way, the finished surface roughness can be significantly improved during cutting.

[0088] The cutting insert 100 according to this embodiment includes a first bottom surface 30 located opposite the rake face 10. The angle of the fourth flank portion 24 relative to the first bottom surface 30 is the same as the angle (first angle θ1) of the first flank portion 21 relative to the rake face 10. The angle of the third flank portion 23 relative to the first bottom surface 30 is the same as the angle (second angle θ2) of the second flank portion 22 relative to the rake face 10. The angle of the second flank portion 22 relative to the first bottom surface 30 is the same as the angle (third angle θ3) of the third flank portion 23 relative to the rake face 10. The angle of the first flank portion 21 relative to the first bottom surface 30 is the same as the angle (fourth angle θ4) of the fourth flank portion 24 relative to the rake face 10. In this manner, the cutting insert 100 can be used upside down.

[0089] The cutting insert 100 according to this embodiment includes a rear cutting edge 60 formed by the ridgeline between the first bottom surface 30 and the flank surface 20. In this way, the workpiece 300 can be cut using not only the blade member 1a forming the front cutting edge 40 but also the blade member 1b forming the rear cutting edge 60, so that an economical cutting insert 100 can be obtained.

[0090] According to the cutting tool 200 of this embodiment, a plane that is parallel to the longitudinal direction (X direction) of the holder 101 and that passes through the corner cutting edge portion 43 is defined as a reference plane A1. When viewed from the longitudinal direction (X direction), the first cutting edge portion 41 is disposed between the reference plane A1 and the second bottom surface 103a. When viewed from a direction perpendicular to the longitudinal direction (Z direction), the second cutting edge portion 42 is disposed farther from the second bottom surface 103a than the reference plane A1. In this manner, the cutting tool 200 can be used to perform drawing on the outer peripheral surface 301 of the workpiece 300.

[0091] According to the cutting tool 200 of this embodiment, a plane that is parallel to the longitudinal direction (X direction) of the holder 101 and that passes through the corner cutting edge portion 43 is defined as a reference plane A2. When viewed from a direction perpendicular to the longitudinal direction (Z direction), the first cutting edge portion 41 is disposed between the reference plane A2 and the second bottom surface 103a. When viewed from the longitudinal direction (X direction), the second cutting edge portion 42 is disposed at a position farther from the second bottom surface 103a than the reference plane A2. In this manner, the cutting tool 200 can be used to perform drawing on the end face 302 of the workpiece 300.

[0092] According to the cutting tool 200 of this embodiment, the recess 103 has a first constraining surface 103b and a second constraining surface 103c. The first constraining surface 103b contacts the third flank portion 23. The second constraining surface 103c contacts the fourth flank portion 24. The first constraining surface 103b is along the third flank portion 23. The second constraining surface 103c is along the fourth flank portion 24. In this way, rotation of the cutting insert 100 and lifting from the holder 101 are suppressed, and misalignment with respect to the holder 101 is reduced.

[0093] <Example> (Sample preparation) Cutting inserts 100 (Samples 1 to 43) having the shapes shown in Tables 1 to 4 were manufactured and evaluated for cutting performance under the following conditions. Tables 1 and 2 show, from the left, the first angle θ1, the second angle θ2, the third angle θ3, and the fourth angle θ4.

[0094] The cutting inserts 100 of Samples 1 to 22 are examples. As shown in Table 1, in the cutting inserts 100 of Samples 1 to 22, the first angle θ1 is 90°, the second angle θ2 is less than 90°, the third angle θ3 is more than 90°, and the fourth angle θ4 is 90°.

[0095] The cutting inserts 100 of Samples 23 to 43 are comparative examples. As shown in Table 2, in the cutting inserts 100 of Samples 23 to 25, Samples 27 to 29, and Samples 38 to 42, the first angle θ1 is 89° or less. In the cutting inserts 100 of Samples 26, 31, and 43, the first angle θ1 is greater than 90°. In the cutting inserts 100 of Samples 30 and Samples 32 to 37, the second angle θ2 is 90°.

[0096] [Table 1]

[0097] [Table 2]

[0098] In Tables 3 and 4, the shape of the draft edge portion and the number of corners are shown from the left. In the cutting inserts 100 of Samples 1 to 43, the fifth angle θ5 is 6°. In the cutting inserts 100 of Samples 1 to 43, the sixth angle θ6 is -6°.

[0099] The cutting inserts 100 of Samples 1 to 43 are attached to a holder 101 as shown in FIGS. 10 and 11. As shown in FIG. 10, when the first cutting edge portion 41 is inclined inward as viewed from the X direction, the fifth angle θ5 is positive. On the other hand, when the first cutting edge portion 41 is inclined outward as viewed from the X direction, the fifth angle θ5 is negative. As shown in FIG. 11, when the second cutting edge portion 42 is inclined outward as viewed from the Z direction, the sixth angle θ6 is negative. On the other hand, when the second cutting edge portion 42 is inclined inward as viewed from the Z direction, the sixth angle θ6 is positive.

[0100] In the cutting inserts 100 of Samples 1 to 7 and Samples 17 to 43, the shape of the drafting edge 44 is linear. In the cutting inserts 100 of Samples 14 to 16, the drafting edge 44 is not provided. In the cutting inserts 100 of Samples 8 to 13, the shape of the drafting edge 44 is curved. In the cutting inserts 100 of Samples 8 to 10, the radius of curvature of the drafting edge 44 is 5 mm. In the cutting inserts 100 of Samples 11 to 13, the radius of curvature of the drafting edge 44 is 40 mm.

[0101] In the cutting inserts 100 of Samples 1 to 18, Samples 27 to 29, Samples 31 to 13, and Samples 38 to 43, two blade members 1a and 1b are attached to the base metal 2, and the number of corners is two (see FIG. 1). In the cutting inserts 100 of Samples 17 to 26, and Samples 34 to 37, one blade member 1a is attached to the base metal 2, and the number of corners is one. In the cutting insert 100 of Sample 30, four blade members are attached to the base metal 2, and the number of corners is four. In the cutting inserts 100 of Samples 1 to 43, the material of the blade members was a cBN-based sintered body.

[0102] [Table 3]

[0103] [Table 4]

[0104] (Processing condition 1) With the cutting insert 100 attached to the holder 101, the outer peripheral surface 301 of the workpiece 300 was subjected to drawing. The outer peripheral surface 301 was machined using the first cutting edge portion 41. The outer peripheral surface 301 was machined under high-efficiency conditions. (work material) Chrome molybdenum steel SCM415H (HRC58-60), diameter = 100 mm, length = 300 mm (Cutting conditions) Cutting speed: Vc = 200 m / min, Feed rate: f = 0.6 mm / revolution, Depth of cut: ap = 0.2 mm, Wet (Processing conditions 2) With the cutting insert 100 attached to the holder 101, an end face 302 of a workpiece 300 was subjected to drawing. The end face 302 was machined using the second cutting edge portion 42. The end face 302 was machined under normal efficiency conditions. (work material) Chrome molybdenum steel SCM415H (HRC58-60), diameter = 100 mm, length = 50 mm (Cutting conditions) Cutting speed: Vc = 200 m / min, Feed rate: f = 0.15 mm / revolution, Depth of cut: ap = 0.2 mm, Wet (Processing condition 3) With the cutting insert 100 attached to the holder 101, the outer peripheral surface 301 of the workpiece 300 was subjected to drawing. The outer peripheral surface 301 was machined using the first cutting edge portion 41. The outer peripheral surface 301 was machined under high-efficiency conditions. (work material) Chrome molybdenum steel SCM415H (HRC58-60), diameter = 100 mm, length = 300 mm (Cutting conditions) Cutting speed: Vc=150m / min, feed rate: f=1.4mm / rotation, depth of cut: ap=0.4mm, wet type (Test results) The results of drawing on the outer peripheral surface 301 and the results of drawing on the end face 302 are shown in Tables 5 and 6. When drawing on the outer peripheral surface 301, the deviation of the cutting insert 100, the fracture resistance of the first cutting edge portion 41, and the finished surface roughness were evaluated.

[0105] The fracture resistance of the first cutting edge portion 41 was evaluated by the amount of shedding of the cutting edge of the first cutting edge portion 41 after the outer periphery of the workpiece 300 had moved 10 km. If the amount of shedding of the cutting edge of the first cutting edge portion 41 was within 0.2 mm, the fracture resistance was rated A. If the amount of shedding of the cutting edge of the first cutting edge portion 41 was more than 0.2 mm, the fracture resistance was rated B.

[0106] The deviation of the cutting insert 100 was evaluated after the outer periphery of the workpiece 300 moved 1 km. FIG. 20 is a plan view schematic diagram showing measurement points P1 and P2 on the holder 101 and the cutting insert 100, respectively. The amount of deviation can be measured by measuring the difference in the X direction between measurement points P1 and P2 shown in FIG. 20. The deviation of the cutting insert 100 was evaluated under the above-mentioned machining condition 3.

[0107] The measurement point P1 is a point on the rake face 10 of the cutting insert 100. Specifically, the width W1 between the measurement point P1 and the corner cutting edge portion 43 in the Z direction is 2 mm. The distance L1 between the measurement point P1 and the corner cutting edge portion 43 in the X direction is 10 mm.

[0108] Measurement point P2 is a point on the first side surface 101a of the holder 101. Specifically, the width between measurement point P2 and the corner cutting edge portion 43 in the Z direction is 2 mm, which is the same as the width W1 between measurement point P1 and the corner cutting edge portion 43. The distance L2 between measurement point P2 and the corner cutting edge portion 43 in the X direction is 20 mm.

[0109] Before machining workpiece 300, the difference d1 in height in the X direction between measurement point P1 and measurement point P2 is calculated. Next, after workpiece 300 is machined (after the outer periphery of workpiece 300 has moved 1 km), the difference d2 in height in the X direction between measurement point P1 and measurement point P2 is calculated. Measurements at measurement points P1 and P2 can be made using a standard dial gauge (2109A-10) made by Mitutoyo.

[0110] The deviation of the cutting insert 100 can be evaluated by the difference d3 in height between the difference d1 and the difference d2. When the difference d3 is less than 2 μm, the deviation of the cutting insert 100 is evaluated as A. When the difference d3 is 2 μm or more, the deviation of the cutting insert 100 is evaluated as B.

[0111] Regarding the finished surface roughness, the surface roughness of the outer peripheral surface 301 of the workpiece 300 was evaluated after the periphery of the workpiece 300 had moved 0.1 km. The surface roughness was evaluated by the maximum height Rz. When the maximum height Rz was 10 μm or less, the finished surface roughness was evaluated as A. When the maximum height Rz was more than 10 μm, the finished surface roughness was evaluated as B.

[0112] The fracture resistance of the second cutting edge portion 42 was evaluated when the end face 302 was subjected to a drawing process. The fracture resistance of the second cutting edge portion 42 was evaluated by the amount of shedding of the cutting edge of the second cutting edge portion 42 after the end face of the workpiece 300 had traveled 10 km. If the amount of shedding of the cutting edge of the second cutting edge portion 42 was within 0.2 mm, the fracture resistance was rated A. If the amount of shedding of the cutting edge of the second cutting edge portion 42 was more than 0.2 mm, the fracture resistance was rated B.

[0113] [Table 5]

[0114] [Table 6]

[0115] As shown in Tables 5 and 6, when the cutting inserts 100 of Samples 1 to 22 were used to perform drawing on the outer peripheral surface 301, the deviation of the cutting inserts 100 and the fracture resistance of the first cutting edge portion 41 were evaluated as A. On the other hand, when the cutting inserts 100 of Samples 23 to 43 were used to perform drawing on the outer peripheral surface 301, at least one of the deviation of the cutting inserts 100 and the fracture resistance of the first cutting edge portion 41 was evaluated as B.

[0116] In particular, in the cutting inserts 100 of Samples 23 to 25, in which the first angle θ1 was 89° or less, the fracture resistance of the first cutting edge portion 41 was evaluated as B. In addition, in the cutting inserts 100 of Samples 26 and 31, in which the first angle θ1 was 95°, the cutting resistance increased, and the deviation of the cutting inserts 100 was evaluated as B. In addition, in the cutting inserts 100 of Samples 27 to 30, Samples 32, and Sample 33, in which the third angle θ3 was 90° or less, the deviation of the cutting inserts 100 was evaluated as B. In the cutting inserts 100 of Samples 34 to 36, in which the fourth angle θ4 was less than 89°, the deviation of the cutting inserts 100 was evaluated as B. In the cutting inserts 100 of Samples 38 to 42, in which the first angle θ1 was less than 89°, the fracture resistance of the first cutting edge portion 41 was evaluated as B, and the deviation of the cutting inserts 100 was evaluated as B. This is believed to be due to an increase in cutting resistance acting on the cutting insert 100.

[0117] When the cutting inserts 100 of Samples 14 to 16, which do not have the cutting edge portion 43, were used to perform drawing on the outer peripheral surface 301, the finished surface roughness of the outer peripheral surface 301 was evaluated as B.

[0118] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present disclosure is defined by the claims, not by the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof. [Explanation of symbols]

[0119] DESCRIPTION OF SYMBOLS 1a, 1b Blade member, 2 Base metal, 4a, 4b Counterbore portion, 5 Through hole, 10 Rake face, 11 First rake face portion, 12 Second rake face portion, 20 Flank face, 21 First flank face portion, 21a First cutting edge portion flank face portion, 21b First base metal flank face portion, 22 Second flank face portion, 22a Second cutting edge portion flank face portion, 22b Second base metal flank face portion, 23 Third flank face portion, 24 Fourth flank face portion, 25 Corner flank face portion, 26 Sweep flank face portion, 30 First bottom surface, 40 Front cutting edge, 41 First cutting edge portion, 42 Second cutting edge portion, 43 Corner cutting edge portion, 44 Sweep flank face portion, 50 Ridge line, 51 First ridge line portion, 52 Second ridge line portion, 53 Third ridge line portion, 54 Fourth ridge line portion, 60 Rear cutting edge, 100 cutting insert, 101 holder, 101a first side surface, 101a1 first top surface region, 101a2 second top surface region, 101b second side surface, 101b1 first side surface region, 101b2 second side surface region, 101c third side surface, 101d fourth side surface, 101e first end surface, 101f second end surface, 102 base plate, 103 recess, 103a second bottom surface, 103b first constraint surface, 103c second constraint surface, 110 holding member, 111 insertion portion, 112 main body portion, 113 mounting hole, 120 fastening screw, 200 cutting tool, 300 workpiece material, 301 outer peripheral surface, 302 end surface, A1, A2 reference surface, D1 first feed direction, D2 second feed direction, R1, R2 Rotation direction, X1, X2 rotation axis, θ1 first angle, θ2 second angle, θ3 third angle, θ4 fourth angle, θ5 fifth angle, θ6 sixth angle, θ7 seventh angle, θ8 eighth angle.

Claims

1. A cutting insert including a rake face, a first flank portion, a second flank portion, a third flank portion, a fourth flank portion, and a front cutting edge formed by a ridge line between the rake face and the first flank portion and the second flank portion, the third flank portion is located opposite the first flank portion with respect to the rake face, the fourth flank portion is located opposite the second flank portion with respect to the rake face, the front cutting edge is formed by a ridgeline between the rake face and the first flank portion, and includes a linear first cutting edge portion; In the first cutting edge portion, an angle formed by the first flank surface portion with respect to the rake face is greater than 89° and less than 91°, an angle formed by the second flank portion with respect to the rake face is less than 90°; an angle formed by the third flank portion with respect to the rake face is greater than 90°; an angle formed by the fourth flank portion with respect to the rake face is greater than 89° and less than 91°; The cutting insert is for turning.

2. The front cutting edge is A corner cutting edge portion, The cutting edge and a second cutting edge portion connected to the corner cutting edge portion, The second cutting edge portion is formed by a ridge line between the rake face and the second flank face portion, The corner cutting edge portion is curved, The cutting insert according to claim 1 , wherein the flattening edge portion is disposed between the first cutting edge portion and the corner cutting edge portion.

3. the cutting insert includes a first bottom surface opposite the rake face; an angle formed by the fourth flank portion with respect to the first bottom surface is the same as an angle formed by the first flank portion with respect to the rake face; an angle formed by the third flank portion with respect to the first bottom surface is the same as an angle formed by the second flank portion with respect to the rake face; an angle formed by the second flank portion with respect to the first bottom surface is the same as an angle formed by the third flank portion with respect to the rake face; The cutting insert according to claim 1 or 2, wherein an angle formed by the first flank portion with respect to the first bottom surface is the same as an angle formed by the fourth flank portion with respect to the rake face.

4. The cutting insert according to claim 3 , further comprising a rear cutting edge defined by a ridge line between the first bottom surface and the third and fourth flank portions.

5. The cutting insert according to claim 2; a holder provided with a recess for restraining the cutting insert; the cutting insert includes a first bottom surface opposite the rake face; The recess has a second bottom surface opposite the first bottom surface.

6. When a plane that is parallel to the longitudinal direction of the holder and passes through the corner cutting edge portion is defined as a reference plane, When viewed from the longitudinal direction, the first cutting edge portion is disposed between the reference surface and the second bottom surface, The cutting tool according to claim 5 , wherein, when viewed from a direction perpendicular to the longitudinal direction, the second cutting edge portion is disposed at a position farther from the second bottom surface than the reference surface.

7. When a plane that is parallel to the longitudinal direction of the holder and passes through the corner cutting edge portion is defined as a reference plane, When viewed from a direction perpendicular to the longitudinal direction, the first cutting edge portion is disposed between the reference surface and the second bottom surface, The cutting tool according to claim 5 , wherein, when viewed from the longitudinal direction, the second cutting edge portion is disposed at a position farther from the second bottom surface than the reference surface.

8. the recess has a first constraining surface in contact with the third flank portion and a second constraining surface in contact with the fourth flank portion, the first constraint surface is along the third relief surface portion, The cutting tool according to claim 5 , wherein the second constraint surface is along the fourth flank portion.

9. the cutting insert includes a blade member and a base metal to which the blade member is attached by a brazing material; the blade member is made of a cBN-based sintered body, The cutting tool according to claim 5 , wherein the base metal is made of cemented carbide.

10. The cutting tool of claim 5 , wherein the holder is made of steel.

11. The cutting tool of claim 5 , further comprising a shim disposed between the second bottom surface and the cutting insert and constructed from a cemented carbide material.

Images