Cutting insert, cutting tool, and method for manufacturing machined product

Abstract

A first outer region of an outer inclined surface of a cutting insert according to an embodiment has a width in a direction perpendicular to a first part of a first edge that decreases with increasing distance from a first corner. A second outer region of the outer inclined surface has a width in a direction perpendicular to a second part of the first edge that increases with increasing distance from a first corner.

Description

[Technical Field]

[0001] The present disclosure relates to cutting inserts, cutting tools, and methods for manufacturing machined workpieces. [Background technology]

[0002] A cutting insert described in Patent Document 1 is known as a cutting insert used in a cutting tool. The cutting insert described in Patent Document 1 has a major cutting edge and a rake face extending from the major cutting edge. In a cross-sectional view, the rake face has a linear portion (referred to as a land portion (6c) in Patent Document 1) and a convexly curved portion protruding upward (referred to as a major rake face (6a) in Patent Document 1). The linear portion is located along the major cutting edge, and the convexly curved portion is located inside the linear portion. By having the convexly curved portion on the rake face, it is possible to prevent chips from contacting the rake face excessively. This improves chip discharge and also slows the progression of wear on the rake face, thereby improving the wear resistance of the rake face. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-032498 Summary of the Invention

[0004] The cutting insert according to the present disclosure has an upper surface, a lower surface located opposite the upper surface, a side surface connected to the upper surface and the lower surface, and a cutting edge located at the intersection of the upper surface and the side surface. The upper surface has corner portions, side portions connected to the corner portions and approaching the lower surface as they move away from the corner portions, outer inclined surfaces extending along the side portions and approaching the lower surface as they move away from the side portions, central inclined surfaces extending along the outer inclined surfaces and approaching the lower surface as they move away from the outer inclined surfaces, inner inclined surfaces extending along the central inclined surfaces and approaching the lower surface as they move away from the central inclined surfaces, and a flat bottom surface connected to the inner inclined surfaces. In a cross section taken along a direction parallel to the insert central axis passing through the centers of the upper and lower surfaces, the outer inclined surfaces are linear, and the central inclined surfaces are convex curved surfaces that protrude upward. The side portions have a first portion connected to the corner portions and a second portion connected to the first portion. The outer inclined surface has a first outer region that extends along the first portion and whose width in a direction perpendicular to the first portion narrows with increasing distance from the corner, and a second outer region that extends along the second portion and whose width in a direction perpendicular to the second portion widens with increasing distance from the corner. The inner inclined surface has a first inner region that extends along the first outer region and whose width in a direction perpendicular to the first portion widens with increasing distance from the corner, and a second inner region that extends along the second outer region and whose width in a direction perpendicular to the second portion narrows with increasing distance from the corner.

[0005] The cutting tool according to the present disclosure has a cylindrical holder extending from a first end to a second end along a rotation axis and having a pocket located on the side of the first end, and a cutting insert according to the present disclosure located in the pocket.

[0006] A method for manufacturing a machined product according to the present disclosure includes the steps of rotating a cutting tool according to the present disclosure, bringing the rotating cutting tool into contact with a workpiece, and removing the cutting tool from the workpiece. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic perspective view of a cutting insert according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic plan view of the cutting insert shown in FIG. [Figure 3] FIG. 2 is a schematic side view of the cutting insert shown in FIG. 1. [Figure 4] FIG. 3 is an enlarged view of part IV in FIG. 2. [Figure 5] FIG. 5 is an enlarged cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is an enlarged cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is an enlarged cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is an enlarged cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 9 is an enlarged cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 3 is an enlarged cross-sectional view taken along line XX in FIG. 2. [Figure 11] FIG. 1 is a schematic perspective view of a cutting tool according to an embodiment of the present disclosure. [Figure 12] FIG. 12 is a schematic perspective view of the cutting tool shown in FIG. 11, viewed from a different angle. [Figure 13] 1A to 1C are schematic diagrams illustrating a method for manufacturing a machined product according to an embodiment of the present disclosure. [Figure 14] 1A to 1C are schematic diagrams illustrating a method for manufacturing a machined product according to an embodiment of the present disclosure. [Figure 15] 1A to 1C are schematic diagrams illustrating a method for manufacturing a machined product according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] The linear portion of the rake face of the cutting insert described in Patent Document 1 extends monotonically along the entire main cutting edge. Therefore, when performing cutting with a large depth of cut, the linear portion of the rake face may come into excessive contact with chips. Therefore, improvements in chip discharge performance and rake face durability are desired.

[0009] According to the present disclosure, it is possible to improve the chip discharge performance and the wear resistance of the outer inclined surface, which is the rake face.

[0010] Hereinafter, a cutting insert, a cutting tool, and a method for manufacturing a machined product according to embodiments of the present disclosure will be described in detail with reference to the drawings. However, for the sake of convenience, the drawings referred to below show only the components necessary for explaining the embodiments in a simplified form. Therefore, the cutting insert and cutting tool according to embodiments of the present disclosure may include any components not shown in the drawings referred to. Furthermore, the dimensions of the components in the drawings do not faithfully represent the actual dimensions of the components and the dimensional ratios of each member.

[0011] In this disclosure, the insert central axis refers to a virtual axis passing through the center of the upper surface of the cutting insert and the center of the lower surface of the cutting insert. Inward or inner side refers to a direction or side of the cutting insert that approaches the insert central axis. Outward or outer side refers to a direction or side of the cutting insert that moves away from the insert central axis. Orthogonal does not necessarily mean strictly orthogonal, but means that an error of about ±5 degrees is allowed. Parallel does not necessarily mean strictly parallel, but means that an error of about ±5 degrees is allowed.

[0012] A cutting insert 10 according to the present disclosure will be described with reference to Fig. 1 to Fig. 10. Fig. 1 is a schematic perspective view of the cutting insert 10 according to an embodiment of the present disclosure. Fig. 2 is a schematic plan view of the cutting insert 10 shown in Fig. 1. Fig. 3 is a schematic side view of the cutting insert 10 shown in Fig. 1. Fig. 3 is a side view from the front of a first side described below. Fig. 4 is an enlarged view of part IV in Fig. 2.

[0013] Fig. 5 is an enlarged cross-sectional view taken along line VV in Fig. 4. Fig. 6 is an enlarged cross-sectional view taken along line VI-VI in Fig. 4. Fig. 7 is an enlarged cross-sectional view taken along line VII-VII in Fig. 4. Fig. 8 is an enlarged cross-sectional view taken along line VIII-VIII in Fig. 4. Fig. 9 is an enlarged cross-sectional view taken along line IX-IX in Fig. 4. Fig. 10 is an enlarged cross-sectional view taken along line XX in Fig. 4.

[0014] The cutting insert 10 of this embodiment is a component of a cutting tool used for cutting (milling) a workpiece W (see FIG. 13) made of a metal material or the like. Examples of cutting the workpiece W include shoulder milling, groove milling, R milling, and profiling.

[0015] As in the example shown in FIGS. 1 to 3 , the cutting insert 10 may have an upper surface 12 and a lower surface 14 located opposite the upper surface 12. The upper surface 12 and the lower surface 14 may each have a polygonal shape, for example, an octagonal shape. In other words, the cutting insert 10 may have a polygonal plate shape, for example, an octagonal plate shape. The upper surface 12 and the lower surface 14 may each have a polygonal shape other than an octagonal shape, such as a triangular shape or a quadrangular shape. In other words, the cutting insert 10 may have a polygonal plate shape other than an octagonal plate shape, such as a triangular plate shape or a quadrangular plate shape. The polygonal shape is not limited to a polygonal shape in the strict sense.

[0016] 1 and 2, the upper surface 12 and the lower surface 14 may each have a rotationally symmetric shape at a certain angle about the insert central axis CS. The upper surface 12 and the lower surface 14 may also have a front-to-back inversion-symmetric shape. In other words, the cutting insert 10 may have a rotationally symmetric shape at a certain angle about the insert central axis CS, or may have a front-to-back inversion-symmetric shape.

[0017] As in the example shown in FIGS. 1 to 3 , the cutting insert 10 may have a side surface 16 located between the upper surface 12 and the lower surface 14. The side surface 16 may be connected to the upper surface 12 and the lower surface 14. The side surface 16 may function as a flank. The cutting insert 10 may also have a mounting hole 18 penetrating from the upper surface 12 to the lower surface 14. One opening of the mounting hole 18 may be located in the center of the upper surface 12, and the other opening of the mounting hole 18 may be located in the center of the lower surface 14. The central axis of the mounting hole 18 may coincide with the insert central axis CS.

[0018] As shown in the example of FIGS. 1 to 3 , the cutting insert 10 may have an upper cutting edge 20 and a lower cutting edge 22. The upper cutting edge 20 may be located at the intersection of the upper surface 12 and the side surface 16. The lower cutting edge 22 may be located at the intersection of the lower surface 14 and the side surface 16. In other words, the cutting insert 10 may be a double-sided insert having an upper cutting edge 20 and a lower cutting edge 22. The upper cutting edge 20 may be located at the entire intersection of the upper surface 12 and the side surface 16, or may be located at a portion of the intersection. The lower cutting edge 22 may be located at the entire intersection of the lower surface 14 and the side surface 16, or may be located at a portion of the intersection.

[0019] 1 and 2, the polygonal upper surface 12 may have a first corner 24 as a corner portion and a second corner 26 as another corner portion. The first corner 24 and the second corner 26 may each have a convex curved shape that protrudes outward when viewed from above.

[0020] 1 and 2, the top surface 12 may have a first side 28 as a side portion connected to the first corner 24, and a second side 30 as another side portion connected to the first corner 24 on the opposite side of the first side 28. The second corner 26 may be connected to the second side 30 on the opposite side of the first corner 24. The first side 28 may have a linear shape in top view, and may approach the bottom surface 14 as it moves away from the first corner 24 in side view. The second side 30 may also have a linear shape in top view.

[0021] In top view, the first side 28 and the second side 30 are not limited to being linear, but may be, for example, a gently convex curved shape that protrudes outward. Here, "a gently convex curved shape" means that the radius of curvature is larger than the radius of curvature of the first corner 24 and the second corner 26, which are convex curved shapes.

[0022] When the upper surface 12 has a shape that is rotationally symmetrical at a certain angle around the insert central axis CS, the upper surface 12 may have a plurality of first corners 24 and a plurality of second corners 26, as in the example shown in Fig. 2. In this case, the plurality of first corners 24 and the plurality of second corners 26 may be positioned alternately along the circumferential direction of the upper surface 12.

[0023] Furthermore, the upper surface 12 may have a plurality of first sides 28 and a plurality of second sides 30. In the case where the upper surface has a plurality of first corners 24, a plurality of second corners 26, a plurality of first sides 28, and a plurality of second sides 30, the following description will focus on one extracted from each of these portions so as to achieve the above-mentioned positional relationship.

[0024] 1 and 2, the upper surface 12 may have a land portion 32 located on its peripheral edge, and the land portion 32 may be connected to the upper cutting edge 20. The land portion 32 may have a function of increasing the cutting edge strength of the upper cutting edge 20. The land portion 32 may be a portion that is adjacent to the upper cutting edge 20 and is indicated by a straight line in a cross section perpendicular to the upper cutting edge 20 when viewed from above.

[0025] As shown in the examples of FIGS. 1 and 4 to 10, the top surface 12 may have an outer inclined surface 34 extending along the first side 28 serving as a side portion, and the outer inclined surface 34 may be connected to the land portion 32 and inclined relative to the land portion 32. The outer inclined surface 34 may approach the bottom surface 14 with increasing distance from the first side 28. The outer inclined surface 34 may have a linear shape in a cross section taken along a direction PD parallel to the insert central axis CS (see FIGS. 5 to 10). The outer inclined surface 34 may function as a rake face. The inclination angle θ of the outer inclined surface 34 with respect to a direction perpendicular to the direction PD parallel to the insert central axis CS may decrease with increasing distance from the first corner 24.

[0026] As shown in the examples of Figures 4 to 10, the upper surface 12 may have an intermediate inclined surface 36 extending along the outer inclined surface 34, and the intermediate inclined surface 36 may be connected to the outer inclined surface 34. The intermediate inclined surface 36 may have a convex curved shape that protrudes upward in a cross section taken along a direction PD parallel to the insert central axis CS. The intermediate inclined surface 36 may have an arc shape, which is one type of convex curved shape, in a cross section taken along a direction PD parallel to the insert central axis CS. The intermediate inclined surface 36 may function as a cutting face.

[0027] As shown in the examples of Figures 1 and 4 to 10, the upper surface 12 may have an inner inclined surface 38 extending along the intermediate inclined surface 36, and the inner inclined surface 38 may be connected to the intermediate inclined surface 36. The inner inclined surface 38 may approach the lower surface 14 as it moves away from the intermediate inclined surface 36. The inner inclined surface 38 may have a concave curved shape recessed downward in a cross section taken along a direction PD parallel to the insert center axis CS. The inner inclined surface 38 may also function as a cutting surface.

[0028] 1 and 2, the upper surface 12 may have a minor inclined surface 40 extending along the second side 30, and the minor inclined surface 40 may be connected to the land portion 32 and inclined relative to the land portion 32. The minor inclined surface 40 may approach the lower surface 14 as it moves away from the second side 30. The minor inclined surface 40 may function as a scooping surface.

[0029] 1 and 2, the upper surface 12 may have a first corner inclined surface 42 located inside the first corner 24. The first corner inclined surface 42 may be connected to the land portion 32, the outer inclined surface 34, the middle inclined surface 36, the inner inclined surface 38, and the minor inclined surface 40. The first corner inclined surface 42 may approach the lower surface 14 as it moves away from the first corner 24. The first corner inclined surface 42 may function as a rake face.

[0030] 1 and 2, the upper surface 12 may have a second corner inclined surface 44 located inside the second corner 26. The second corner inclined surface 44 may be connected to the land portion 32 and the minor inclined surface 40. The second corner inclined surface 44 may approach the lower surface 14 as it moves away from the second corner 26. The second corner inclined surface 44 may also function as a rake face.

[0031] 1 and 2, the top surface 12 may have a flat bottom surface 46 that surrounds the opening of the mounting hole 18, and the bottom surface 46 may be perpendicular to the insert central axis CS. The bottom surface 46 may be connected to the inner inclined surface 38, the minor inclined surface 40, the first corner inclined surface 42, and the second corner inclined surface 44.

[0032] As in the example shown in FIGS. 1 to 3 , the upper cutting edge 20 may have a major cutting edge 48 located on the first side 28. The major cutting edge 48 is a portion that can function as a main cutting edge in cutting the workpiece W. The major cutting edge 48 may be located on the entire first side 28, or on a part of the first side 28. The major cutting edge 48 may have a linear shape when viewed from above.

[0033] As in the example shown in Figures 1 to 3, the upper cutting edge 20 may have a minor cutting edge 50 located on the second side 30. The minor cutting edge 50 may function as a wiper edge for finishing the machined surface of the workpiece W. The minor cutting edge 50 may be located on the entire second side 30, or on a part of the second side 50. The minor cutting edge 50 may have a linear shape when viewed from above.

[0034] As shown in the example of FIGS. 1 and 2 , the upper cutting edge 20 may have a first corner edge 52 located at the first corner 24, and the first corner edge 52 may be connected to the major cutting edge 48 and the minor cutting edge 50. The first corner edge 52 may have a convex curved shape that protrudes outward in a top view. The upper cutting edge 20 may also have a second corner edge 54 located at the second corner 26, and the second corner edge 54 may be connected to the minor cutting edge 50. The second corner edge 54 may have a convex curved shape that protrudes outward in a top view.

[0035] 4, a first side 28 serving as a side portion may have a first portion 28a connected to a first corner 24 serving as a corner portion, a second portion 28b connected to the first portion 28a, and a third portion 28c connected to the second portion 28b. In the first side 28, a length Lb of the second portion 28b may be longer than a length La of the first portion 28a. In the first side 28, a length Lc of the third portion 28c may be longer than the length La of the first portion 28a and the length Lb of the second portion 28b.

[0036] As shown in the example of FIG. 4 , the outer inclined surface 34 may have a first outer region 34a extending along the first portion 28a of the first side 28. In the first outer region 34a of the outer inclined surface 34, a width Wao in a direction perpendicular to the first portion 28a of the first side 28 may decrease with increasing distance from the first corner 24. The outer inclined surface 34 may also have a second outer region 34b extending along the second portion 28b of the first side 28. In the second outer region 34b of the outer inclined surface 34, a width Wbo in a direction perpendicular to the second portion 28b of the first side 28 may increase with increasing distance from the first corner 24. The outer inclined surface 34 may also have a third outer region 34c extending along the third portion 28c of the first side 28. In the third outer region 34c of the outer inclined surface 34, the width Wco in the direction perpendicular to the third portion 28c of the first side 28 may become narrower with increasing distance from the first corner 24.

[0037] As shown in the example of FIG. 4 , the central inclined surface 36 may have a first central region 36a extending along the first outer region 34a of the outer inclined surface 34. In the first central region 36a of the central inclined surface 36, a width Wam in a direction perpendicular to the first portion 28a of the first side 28 may increase with increasing distance from the first corner 24. The central inclined surface 36 may have a second central region 36b extending along the second outer region 34b of the outer inclined surface 34. In the second central region 36b of the central inclined surface 36, a width Wbm in a direction perpendicular to the second portion 28b of the first side 28 may decrease with increasing distance from the first corner 24. The central inclined surface 36 may have a third central region 36c extending along the third outer region 34c of the outer inclined surface 34. In the third middle region 36c of the middle inclined surface 36, the width Wcm in the direction perpendicular to the third portion 28c of the first side 28 may increase with increasing distance from the first corner 24.

[0038] 5 and 6 , in the first middle region 36a of the middle inclined surface 36, the radius of curvature Ra of the first middle region 36a in a cross section taken along the direction PD parallel to the insert central axis CS may increase with increasing distance from the first corner 24. In other words, in the first middle region 36a of the middle inclined surface 36, the curvature of the first middle region 36a in a cross section taken along the direction PD parallel to the insert central axis CS may decrease with increasing distance from the first corner 24.

[0039] 7 and 8, in the second middle region 36b of the middle inclined surface 36, the radius of curvature Rb of the second middle region 36b in a cross section taken along the direction PD parallel to the insert central axis CS may decrease with increasing distance from the first corner 24. As in the example shown in Figures 9 and 10, in the third middle region 36c of the middle inclined surface 36, the radius of curvature Rc of the third middle region 36c in a cross section taken along the direction PD parallel to the insert central axis CS may increase with increasing distance from the first corner 24.

[0040] As shown in the examples of FIGS. 4 to 10 , the inner inclined surface 38 may have a first inner region 38a extending along the first middle region 36a of the middle inclined surface 36. The first inner region 38a of the inner inclined surface 38 may have a width Wai in a direction perpendicular to the first portion 28a of the first side 28 that narrows with increasing distance from the first corner 24. The inner inclined surface 38 may have a second inner region 38b extending along the second middle region 36b of the middle inclined surface 36. The second inner region 38b of the inner inclined surface 38 may have a width Wbi in a direction perpendicular to the second portion 28b of the first side 28 that widens with increasing distance from the first corner 24. The inner inclined surface 38 may have a third inner region 38c extending along the third middle region 36c of the middle inclined surface 36. The third inner region 38c of the inner inclined surface 38 may have a width Wci in a direction perpendicular to the first portion 28a of the first side 28 that narrows with increasing distance from the first corner 24.

[0041] 1 to 3, when the upper surface 12 and the lower surface 14 have shapes that are inversion symmetrical from front to back, the lower surface 14 may have portions corresponding to the first corner 24, the second corner 26, the first side 28, the second side 30, the land portion 32, the outer inclined surface 34, the middle inclined surface 36, the inner inclined surface 38, the minor inclined surface 40, the first corner inclined surface 42, and the second corner inclined surface 44 on the upper surface 12. The configurations of the portions corresponding to the first corner 24, the second corner 26, the first side 28, the second side 30, etc. on the lower surface 14 may be the same as the configurations of the first corner 24, the second corner 26, the first side 28, the second side 30, etc. on the upper surface 12, except that the positional relationship in the up-down direction is reversed.

[0042] 1 to 3, when the upper surface 12 and the lower surface 14 have inversion-symmetric shapes, the lower cutting edge 22 may have portions corresponding to the major cutting edge 48, the minor cutting edge 50, the first corner edge 52, and the second corner edge 54 of the upper cutting edge 20. The configurations of the portions corresponding to the major cutting edge 48, the minor cutting edge 50, the first corner edge 52, and the second corner edge 54 of the lower cutting edge 22 may be the same as the configurations of the major cutting edge 48, the minor cutting edge 50, the first corner edge 52, and the second corner edge 54 of the upper cutting edge 20, except that the positional relationship in the up-down direction is reversed.

[0043] Examples of the material of the cutting insert 10 include cemented carbide and cermet. Examples of cemented carbide compositions include WC-Co, which is produced by adding cobalt (Co) powder to tungsten carbide (WC) and sintering the resulting mixture; WC-TiC-Co, which is produced by adding titanium carbide (TiC) to WC-Co; and WC-TiC-TaC-Co, which is produced by adding tantalum carbide (TaC) to WC-TiC-Co. Cermet is a sintered composite material in which a ceramic component is combined with a metal, and specific examples include sintered composite materials whose main component is a titanium compound such as titanium carbide (TiC) or titanium nitride (TiN).

[0044] The surface of the cutting insert 10 may be coated with a coating by chemical vapor deposition (CVD) or physical vapor deposition (PVD), and the coating may have a composition such as titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), or alumina (Al2O3).

[0045] 4, the first outer region 34a of the outer inclined surface 34 has a width Wao that narrows in a direction perpendicular to the first portion 28a of the first side 28 with increasing distance from the first corner 24. The second outer region 34b of the outer inclined surface 34 has a width Wbo that widens in a direction perpendicular to the second portion 28b of the first side 28 with increasing distance from the first corner 24. Therefore, the width of the outer inclined surface 34 changes in the following order from the first corner 24 side: wide, narrow, and wide again. In other words, the outer inclined surface 34 has a wide portion, a narrow portion, and a wide portion arranged in this order from the first corner 24 side.

[0046] As a result, when performing cutting with a small depth of cut or a medium depth of cut, the wide portions of the outer inclined surface 34 can control and stabilize the flow of chips. When performing cutting with a large depth of cut, the narrow portions of the outer inclined surface 34 are more likely to separate from the chips, preventing the outer inclined surface 34 from coming into excessive contact with the chips. When performing cutting with a large depth of cut, the two wide portions of the outer inclined surface 34 can support the chips and stabilize the flow of the chips. Therefore, according to the example embodiment of the present disclosure, it is possible to improve chip discharge performance and slow the progression of wear on the outer inclined surface 34, thereby improving the wear resistance of the outer inclined surface 34, which is the rake face.

[0047] The first middle region 36a of the middle inclined surface 36 has a width Wam that increases in a direction perpendicular to the first portion 28a of the first side 28 with increasing distance from the first corner 24. The second middle region 36b of the middle inclined surface 36 has a width Wbm that decreases in a direction perpendicular to the second portion 28b of the first side 28 with increasing distance from the first corner 24.

[0048] Therefore, the width of the middle inclined surface 36 changes in the order of narrow width, wide width, and narrow width from the first corner 24 side in response to the change in width of the outer inclined surface 34. In other words, the middle inclined surface 36 has a narrow portion, a wide portion, and a narrow portion arranged in that order from the first corner 24 side. This makes it easier to ensure a sufficient thickness in the vicinity of the narrow portion of the outer inclined surface 34. Therefore, according to the example of the embodiment of the present disclosure, damage such as chipping is less likely to occur in the upper cutting edge 20, and the durability of the cutting insert 10 can be improved.

[0049] The radius of curvature Ra of the first middle region 36a may increase as the first middle region 36a of the middle inclined surface 36 moves away from the first corner 24. When performing cutting with a small or medium depth of cut, the first middle region 36a of the middle inclined surface 36 can control and stabilize the flow of chips.

[0050] The radius of curvature Rb of the second middle region 36b of the middle inclined surface 36 may become smaller as the second middle region 36b becomes farther from the first corner 24. When performing cutting with a large depth of cut, it is possible to easily prevent chips from coming into excessive contact with the outer inclined surface 34.

[0051] The inclination angle θ of the outer inclined surface 34 may decrease as the outer inclined surface 34 moves away from the first corner 24. When performing cutting with a large depth of cut, the two wide portions of the outer inclined surface 34 can support the chips, stabilizing the flow of the chips.

[0052] In the first side 28, the length Lb of the second portion 28b may be longer than the length La of the first portion 28a. The boundary between the first portion 28a and the second portion 28b in the first side 28 can be brought closer to the first corner 24. That is, the boundary between the first outer region 34a and the second outer region 34b and the boundary between the first middle region 36a and the second middle region 36b can be brought closer to the first corner 24. Therefore, even in cutting with a relatively small depth of cut, it is possible to improve the chip discharge performance, the wear resistance of the outer inclined surface 34, and the durability of the cutting insert 10.

[0053] The first inner region 38a of the inner inclined surface 38 may have a width Wai in a direction perpendicular to the first portion 28a of the first side 28 that narrows with increasing distance from the first corner 24. The second inner region 38b of the inner inclined surface 38 may have a width Wbi in a direction perpendicular to the second portion 28b of the first side 28 that widens with increasing distance from the first corner 24.

[0054] In this case, the width Wam of the first middle region 36a tends to increase with increasing distance from the first corner 24. That is, there is a high degree of design freedom regarding the change in the width Wam of the first middle region 36a. Also, the width Wbm of the second middle region 36b tends to decrease with increasing distance from the first corner 24. That is, there is a high degree of design freedom regarding the change in the width Wbm of the second middle region 36b. Also, the width of the middle inclined surface 36 in the direction perpendicular to the first portion 28a at the boundary between the first middle region 36a and the second middle region 36b can be increased while preventing the distance from the boundary between the first portion 28a and the second portion 28b of the first side 28 to the bottom surface 46 from becoming excessively large.

[0055] The third outer region 34c of the outer inclined surface 34 may have a width Wco that narrows in a direction perpendicular to the third portion 28c of the first side 28 with increasing distance from the first corner 24. The third middle region 36c of the middle inclined surface 36 may have a width Wcm that widens in a direction perpendicular to the third portion 28c of the first side 28 with increasing distance from the first corner 24.

[0056] When the third outer region 34c has the above-described configuration, the outer inclined surface 34 can be prevented from excessively contacting chips. When the third portion 28c of the first side 28 is used as part of the main cutting edge 48, the depth of cut is very large, and chips tend to come into contact with a wide area of ​​the outer inclined surface 34. However, because the contact area with chips in the third outer region 34c can be reduced, excessive contact with chips can be avoided, as described above. Furthermore, rather than narrowing the width Wco of the entire third outer region 34c, the width Wco narrows with increasing distance from the first corner 24. Therefore, the two wide portions of the outer inclined surface 34 support the chips, easily maintaining their function of stabilizing the flow of chips.

[0057] Furthermore, when the third middle region 36c has the above-described configuration, it becomes easier to ensure the thickness of the main cutting edge 48 in the vicinity of the narrow portion of the width Wco in the third outer region 34c. Therefore, according to the example of the embodiment of the present disclosure, damage such as chipping is less likely to occur in the upper cutting edge 20, and the durability of the cutting insert 10 can be improved.

[0058] The radius of curvature Rc of the third middle region 36c may increase as the third middle region 36c of the middle inclined surface 36 moves away from the first corner 24. When the third middle region 36c has the above configuration, it becomes easier to ensure the thickness of the main cutting edge 48 near the narrow portion of the width Wco in the third outer region 34c. Therefore, according to the example of the embodiment of the present disclosure, damage such as chipping is less likely to occur in the upper cutting edge 20, and the durability of the cutting insert 10 can be improved.

[0059] The third portion 28c of the first side 28 may be longer than the first portion 28a and the second portion 28b. The two wide portions of the outer inclined surface 34 are unlikely to be located far away from the first corner 24. Therefore, even in cutting with a relatively small depth of cut, the two wide portions of the outer inclined surface 34 are likely to support chips and maintain their function of stabilizing the flow of chips.

[0060] <Cutting tools> A cutting tool 56 according to an embodiment of the present disclosure will be described with reference to Figures 11 and 12. Figure 11 is a schematic perspective view of the cutting tool 56 according to an embodiment of the present disclosure. Figure 12 is a schematic perspective view of the cutting tool 56 shown in Figure 11 as viewed from a different angle.

[0061] As shown in the examples of FIGS. 11 and 12 , a cutting tool 56 according to an embodiment of the present disclosure is a tool used for cutting a workpiece W (see FIG. 13 ) and rotatable about a rotation axis RS. The cutting tool 56 may have a holder 58 attached to a spindle of a processing machine such as a milling machine. The holder 58 may have a cylindrical shape extending from a first end 58 a to a second end 58 b along the rotation axis RS. Examples of materials for the holder 58 include metals such as stainless steel, carbon steel, cast iron, and aluminum alloy. A plurality of pockets 60 may be positioned circumferentially at intervals on the outer circumferential surface of the holder 58. The plurality of pockets 60 may be positioned at equal intervals in the circumferential direction or at unequal intervals in the circumferential direction. The number of pockets 60 may be one.

[0062] 11 and 12 , a cutting tool 56 may have a cutting insert 10 positioned in a pocket 60 of a holder 58. The cutting insert 10 may be positioned only in one or more selected pockets 60 in the holder 58. The cutting insert 10 may also be fixed to the pocket 60 of the holder 58 by a fixing screw 62 inserted through the mounting hole 18. The cutting insert 10 may also be fixed to the pocket 60 of the holder 58 by a clamping member.

[0063] <Method of manufacturing machined products> A method for manufacturing a machined product according to an embodiment of the present disclosure will be described with reference to Fig. 13 to Fig. 15. Fig. 13 to Fig. 15 are schematic views for explaining a method for manufacturing a machined product according to an embodiment of the present disclosure.

[0064] As shown in the examples of FIGS. 13 to 15 , the method for manufacturing a machined product according to an embodiment of the present disclosure is a method for manufacturing a machined product M, which is a workpiece W that has been machined, and includes a first step, a second step, and a third step. The first step is a step of rotating a cutting tool 56. The second step is a step of bringing the rotating cutting tool 56 into contact with the workpiece W. The third step is a step of separating the cutting tool 56 from the workpiece W. Examples of materials for the workpiece W include aluminum alloy, stainless steel, carbon steel, alloy steel, cast iron, and non-ferrous metal. Specific details of the method for manufacturing a machined product according to an embodiment of the present disclosure are as follows.

[0065] 13 and 14, the cutting tool 56 is rotated in the rotation direction T and moved in the direction of the arrow FD to approach the workpiece W. Then, the cutting insert 10 of the rotating cutting tool 56 is moved further in the direction of the arrow FD while being brought into contact with the workpiece W. As a result, the cutting tool 56 cuts the workpiece W, and a machined surface Wf is formed on the workpiece W as in the example shown in FIG.

[0066] 15, the cutting tool 56 is then moved in the direction of arrow FD to separate it from the workpiece W. This completes the cutting of the workpiece W, and a machined product M can be produced, which is the machined workpiece W. Because the cutting tool 56 has excellent cutting ability for the reasons described above, it is possible to produce a machined product M with excellent machining precision.

[0067] To continue the cutting process, the cutting insert 10 of the cutting tool 56 may be repeatedly brought into contact with different locations on the workpiece W while the cutting tool 56 is being rotated. In the embodiment of the present disclosure, the cutting tool 56 is brought close to the workpiece W, but since it is only necessary that the cutting tool 56 and the workpiece W are brought relatively close to each other, for example, the workpiece W may be brought close to the cutting tool 56. In this regard, the cutting tool 56 is also moved away from the workpiece W in the same manner.

[0068] The invention according to the present disclosure has been described above based on the drawings and embodiments. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and embodiments obtained by appropriately combining the disclosed technical means are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art can easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure. [Explanation of symbols]

[0069] 10 Cutting insert 12 Top side 14 Bottom side 16 Side 18 Mounting holes 20 Upper cutting edge 22 Lower cutting edge 24 First corner (corner part) 26 Second corner (other corners) 28 First side (side) 28a Part 1 28b 2nd part 28c 3rd part 30 Second side (other side) 32 Land Department 34 External slope 34a 1st outer area 34b Second outer area 34c Third outer area 36 Medium slope 36a 1st middle area 36b 2nd middle area 36c 3rd middle area 38 Inner slope 38a 1st inner area 38b Second inner area 38c 3rd inner area 40 Secondary slope 42 First corner inclined surface 44 Second corner inclined surface 46 bottom 48 Main cutting edge 50 Minor cutting edge 52 1st corner blade 54 2nd corner blade 56 Cutting tools 58 Holder 60 pockets 62 Fixing screw CS Insert center axis PD: Parallel to the insert axis RS Rotating Axis

Claims

1. The top surface and a lower surface located opposite the upper surface; a side surface connected to the upper surface and the lower surface; a cutting edge located at an intersection of the top surface and the side surface, The upper surface is Corner portion, a side portion connected to the corner portion and approaching the lower surface as it moves away from the corner portion; an outer inclined surface that extends along the side portion and approaches the lower surface as it moves away from the side portion; an intermediate inclined surface that extends along the outer inclined surface and approaches the lower surface as it moves away from the outer inclined surface; an inner inclined surface that extends along the central inclined surface and approaches the lower surface as it moves away from the central inclined surface; a flat bottom surface connected to the inner inclined surface; In a cross section taken along a direction parallel to an insert central axis passing through a center of the upper surface and a center of the lower surface and perpendicular to the side portion, the outer inclined surface has a linear shape, and the middle inclined surface has a convex curved shape protruding upward, The side portion is a first portion connected to the corner portion; a second portion connected to the first portion, The outer inclined surface is a first outer region extending along the first portion; a second outer region extending along the second portion; The intermediate inclined surface is a first middle region extending along the first outer region; a second middle region extending along the second outer region, When viewed from the front of the bottom surface, a width of the first outer region in a direction perpendicular to the first portion narrows with increasing distance from the corner portion, a width of the second outer region in a direction perpendicular to the second portion increases with increasing distance from the corner portion, a width of the first middle region in a direction perpendicular to the first portion increases with increasing distance from the corner portion; The cutting insert, wherein the width of the second intermediate region in a direction perpendicular to the second portion becomes narrower with increasing distance from the corner portion.

2. In a cross section taken along a direction parallel to the insert central axis and perpendicular to the side portion, the middle inclined surface has an arc shape, 2. The cutting insert according to claim 1, wherein a radius of curvature of the first intermediate region in a cross section taken along a direction parallel to the insert center axis and perpendicular to the side portion increases with increasing distance from the corner portion.

3. 3. The cutting insert according to claim 2, wherein a radius of curvature of the second middle region in a cross section taken along a direction parallel to the insert center axis and perpendicular to the side portion decreases with increasing distance from the corner portion.

4. The cutting insert according to claim 1 , wherein an inclination angle of the outer inclined surface with respect to a direction perpendicular to the parallel direction decreases with increasing distance from the corner portion.

5. The cutting insert according to claim 1 , wherein the second portion has a length longer than the first portion.

6. The inner inclined surface is a first inner region extending along the first middle region; a second inner region extending along the second middle region, When viewed from the front of the bottom surface, a width of the first internal region in a direction perpendicular to the first portion narrows with increasing distance from the corner portion; The cutting insert according to claim 1 , wherein a width of the second interior region in a direction perpendicular to the second portion increases with increasing distance from the corner portion.

7. The side portion further includes a third portion connected to the second portion, the outer inclined surface further includes a third outer region extending along the third portion, the middle inclined surface further includes a third middle region extending along the third outer region, When viewed from the front of the bottom surface, a width of the third outer region in a direction perpendicular to the third portion narrows with increasing distance from the corner portion, The cutting insert according to claim 1 , wherein a width of the third middle region in a direction perpendicular to the third portion increases with increasing distance from the corner portion.

8. In a cross section taken along a direction parallel to the insert central axis and perpendicular to the side portion, the middle inclined surface has an arc shape, 8. The cutting insert according to claim 7, wherein a radius of curvature of the third middle region in a cross section taken along a direction parallel to the insert center axis and perpendicular to the side portion increases with increasing distance from the corner portion.

9. The cutting insert according to claim 7 , wherein a length of the third portion is longer than a length of the first portion and a length of the second portion.

10. a cylindrical holder extending from a first end to a second end along a rotation axis and having a pocket located on the first end side; and a cutting insert according to any one of claims 1 to 9 located in the pocket.

11. rotating the cutting tool of claim 10; bringing the rotating cutting tool into contact with a workpiece; and removing the cutting tool from the workpiece.

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