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

Abstract

The purpose of the present invention is to achieve both an improvement in the surface precision of a machined surface of a workpiece and an improvement in the durability of a cutting insert. In a cross-section orthogonal to the outer edge of the upper surface, the main rake surface has a linear shape so as to approach the reference surface as the main rake surface moves away from the land surface. The land surface has a first land surface disposed along the corner portion and a second land surface disposed along the edge portion. The first land surface has a first linear portion having a linear shape in a cross-section orthogonal to the corner portion, and the entire second land surface has a convex curve shape in a cross-section orthogonal to the side portion.

Description

Technical Field

[0001] The present disclosure relates to a cutting insert, a cutting tool and a method for manufacturing a cut product used for cutting a workpiece. Background Art

[0002] As a cutting insert used for cutting a workpiece formed of metal or the like, for example, the cutting inserts described in Patent Documents 1 and 2 are known. The cutting inserts described in Patent Documents 1 and 2 include: a land surface (referred to as a first rake surface in Patent Document 1 and a land surface in Patent Document 2), which is arranged along the outer edge of its upper surface; and a rake surface, which is arranged along the land surface. The cutting insert includes a land surface, thereby improving the tip strength of the cutting edge and improving the durability of the cutting insert. Therefore, in the case of cutting processing such as semi-roughing that imposes a large cutting load on the cutting edge, a cutting insert with a land surface is actively used. In the cutting inserts described in Patent Documents 1 and 2, the shape of the land surface in the cross section orthogonal to the outer edge of their upper surface (hereinafter, appropriately referred to as the cross-sectional shape of the land surface) is a straight line shape, but there are also cases where the cross-sectional shape of the land surface is a convex curve shape.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2011 / 037186

[0006] Patent Document 2: International Publication No. 2015 / 141428 Summary of the invention

[0007] The cutting insert disclosed in the present invention comprises: an upper surface; a lower surface, which is located on the opposite side of the upper surface; a side surface, which is located between the upper surface and the lower surface; and a cutting edge, which is located at the intersection of the upper surface and the side surface. An imaginary axis passing through the center of the upper surface and the center of the lower surface is used as the insert center axis, and an imaginary plane located between the upper surface and the lower surface and orthogonal to the insert center axis is used as a reference plane. The upper surface comprises: an outer edge, which has a corner portion in a convex curve shape and a side portion in a straight line shape extending from the corner portion; a land surface, which is arranged along the outer edge; and a straight-line-shaped front cutting edge, which is located along the land surface and becomes a straight line shape in a cross section orthogonal to the outer edge as it moves away from the land surface and approaches the reference plane. The land surface comprises a first land surface arranged along the corner portion and a second land surface arranged along the side portion. The first land surface has a first straight line portion in a straight line shape in a cross section orthogonal to the corner portion. The entire second land surface is in a convex curve shape in a cross section orthogonal to the side portion.

[0008] The cutting tool disclosed in the present invention comprises a tool holder and a cutting insert disclosed in the present invention. The tool holder is in the shape of a rod extending from a first end toward a second end and has a tool groove located on the first end side. The cutting insert is located in the tool groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic perspective view of a cutting insert according to an embodiment of the present disclosure.

[0010] Figure 2 yes Figure 1 A schematic top view of a cutting insert is shown.

[0011] Figure 3 yes Figure 2 An enlarged view of part III in FIG.

[0012] Figure 4 The IVA is along the lines of Figure 3 Schematic cross-sectional view of the IVA-IVA line in FIG. Figure 4 The IVB is Figure 4 Magnified view of the F1 part of IVA.

[0013] Figure 5 The VA is along Figure 3 Schematic cross-sectional view of the VA-VA line in FIG. Figure 5 VB is Figure 5 Magnified view of the F2 section of VA.

[0014] Figure 6 The VIA is along Figure 3 Schematic cross-sectional view of the VIA-VIA line in FIG. Figure 6 The VIB is Figure 6 Magnified view of the F3 portion of VIA.

[0015] Figure 7 The VIIA is along Figure 3 Schematic cross-sectional view of line VIIA-VIIA in FIG. Figure 7 VIIB is Figure 7 Magnified view of the F4 section of VIIA.

[0016] Figure 8 The VIIIA is along the Figure 3 Schematic cross-sectional view of line VIIIA-VIIIA in FIG. Figure 8 VIIIB is Figure 8 Magnified view of the F5 section of VIIIA.

[0017] Fig. 9 is a schematic perspective view of a cutting tool according to an embodiment of the present disclosure.

[0018] Fig.10This is a schematic diagram for explaining a method for producing a machined product according to an embodiment of the present disclosure.

[0019] Fig.11 This is a schematic diagram for explaining a method for producing a machined product according to an embodiment of the present disclosure.

[0020] Fig.12 This is a schematic diagram for explaining a method for producing a machined product according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] In the case where the cross-sectional shape of the land surface is a straight line shape, the cutting edge is sharpened to improve the sharpness of the cutting edge, thereby improving the surface accuracy of the machined surface of the cut piece. On the other hand, the cutting edge is prone to edge defects, etc., and there is a concern that the durability of the cutting blade will be reduced. In addition, in the case where the cross-sectional shape of the land surface is a convex curve shape, the cutting edge is not prone to edge defects, etc., and the durability of the cutting blade is improved. On the other hand, it is difficult to improve the sharpness of the cutting edge, and there is a concern that the surface accuracy of the machined surface of the cut piece will be reduced. In recent years, there has been a desire to balance the improvement of the surface accuracy of the machined surface of the cut piece with the improvement of the durability of the cutting blade.

[0022] According to the present disclosure, it is possible to achieve both improvement in the surface accuracy of the machined surface of the workpiece and improvement in the durability of the cutting insert.

[0023] Hereinafter, the cutting insert, cutting tool and method for manufacturing a cut product according to the embodiment of the present disclosure will be described in detail using the accompanying drawings. However, for ease of description, the following figures referred to only simplify the components required for describing the embodiment. Therefore, the cutting insert and cutting tool according to the embodiment of the present disclosure may have any components not shown in the figures referred to. In addition, the dimensions of the components in the figures do not accurately represent the dimensions of the actual components and the dimensional ratios of the components.

[0024] In the present disclosure, the term "orthogonal" is not limited to being strictly orthogonal, but means that an error of about ±5 degrees is allowed. The term "parallel" is not limited to being strictly parallel, but means that an error of about ±5 degrees is allowed.

[0025] <Cutting insert>

[0026] Reference Figures 1 to 8 , a cutting insert 10 according to an embodiment of the present disclosure will be described. Figure 1 1 is a schematic perspective view of a cutting insert 10 according to an embodiment of the present disclosure. Figure 2 yes Figure 1 A schematic top view of a cutting insert 10 is shown. Figure 3 yes Figure 2 An enlarged view of part III in FIG. Figure 4The IVA is along the lines of Figure 3 Schematic cross-sectional view of the IVA-IVA line in FIG. Figure 4 The IVB is Figure 4 Magnified view of the F1 part of IVA. Figure 5 The VA is along Figure 3 Schematic cross-sectional view of the VA-VA line in FIG. Figure 5 VB is Figure 5 Magnified view of the F2 section of VA. Figure 6 The VIA is along Figure 3 Schematic cross-sectional view of the VIA-VIA line in FIG. Figure 6 The VIB is Figure 6 Magnified view of the F3 portion of VIA. Figure 7 The VIIA is along Figure 3 Schematic cross-sectional view of line VIIA-VIIA in FIG. Figure 7 VIIB is Figure 7 Magnified view of the F4 section of VIIA. Figure 8 The VIIIA is along the Figure 3 Schematic cross-sectional view of line VIIIA-VIIIA in FIG. Figure 8 VIIIB is Figure 8 Magnified view of the F5 section of VIIIA.

[0027] like Figure 1 and Figure 2 As shown in the example, the cutting insert 10 can be used for a workpiece W (see Fig.10 ) is a replaceable blade for cutting processing. The cutting blade 10 can have an upper surface 12 and a lower surface 14 located on the opposite side of the upper surface 12. The upper surface 12 and the lower surface 14 can be respectively quadrilateral. In other words, the cutting blade 10 can be a quadrangular plate shape. The upper surface 12 and the lower surface 14 can also be respectively polygonal shapes other than quadrilateral shapes such as triangles or pentagons. In other words, the cutting blade 10 can also be a polygonal plate shape other than quadrangular plates such as triangles or pentagons. The so-called polygonal shape is not limited to a polygonal shape in a strict sense.

[0028] like Figure 1 and Figure 2 As shown in the example, upper surface 12 and lower surface 14 can be respectively symmetrical shapes of rotation every constant angle around the blade center axis CS. In other words, cutting insert 10 can be symmetrical shapes of rotation every constant angle around the blade center axis CS. Blade center axis CS refers to the imaginary axis through the center of upper surface 12 and the center of lower surface 14.

[0029] The cutting insert 10 may include a plurality of side surfaces 16 located between the upper surface 12 and the lower surface 14. The plurality of side surfaces 16 may be connected to the upper surface 12 and the lower surface 14, respectively. The side surfaces 16 may also function as relief surfaces.

[0030] The cutting insert 10 may include a mounting hole 18 extending from the upper surface 12 to the lower surface 14. One opening of the mounting hole 18 may be located at the center of the upper surface 12, and the other opening of the mounting hole 18 may be located at the center of the lower surface 14. The central axis of the mounting hole 18 may coincide with the insert central axis CS.

[0031] The cutting insert 10 may include a cutting edge E located at the intersection of the upper surface 12 and the side surface 16. The cutting edge E 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.

[0032] like Figure 1 and Figure 2 As shown in the example, the upper surface 12 may have an outer edge 12p as the outline of the upper surface 12. The outer edge 12p of the upper surface 12 may have a first corner 20 as a corner portion and a second corner 22 as another corner portion. The first corner 20 and the second corner 22 may be alternately located at the outer edge 12p of the upper surface 12. The first corner 20 and the second corner 22 may also be convex curve shapes that protrude outward when viewed from above. The so-called top view is synonymous with observing the upper surface 12 from the front. The so-called outward direction is a direction away from the center axis CS of the blade.

[0033] like Figure 1 and Figure 2 As shown in the example, the outer edge 12p of the upper surface 12 may have two side portions 24 extending from each first corner 20. Each side portion 24 may be connected to the second corner 22. Each side portion 24 may be a straight line shape when viewed from above. The so-called straight line shape when viewed from above is not limited to a strict straight line shape when viewed from above, but includes a slightly curved shape.

[0034] like Figures 1 to 3 As shown in the example, the upper surface 12 may also have a land surface 26 arranged along the outer edge 12p. It should be noted that the above-mentioned "arranged along" means that the two target areas extend in the same direction. Therefore, the two target areas may be separated from each other or may be in contact with each other.

[0035] For example, the land surface 26 being provided along the outer edge 12p means that the land surface 26 extends in accordance with the shape of the outer edge 12p. In this case, the land surface 26 may be connected to the outer edge 12p or may be slightly separated from the outer edge 12p.

[0036] Since the cutting edge E is located at the outer edge 12p, the land surface 26 may be provided along the cutting edge E. The land surface 26 may also have the function of increasing the edge strength of the cutting edge E. A part of the land surface 26 may also function as a rake face. The land surface 26 may also be connected to the cutting edge E.

[0037] like Figures 1 to 5 As shown in the example, the upper surface 12 may also have a main rake face 28 provided along the land surface 26 at a position inner than the land surface 26. The main rake face 28 may mainly function as a rake face. The main rake face 28 may be connected to the land surface 26. The main rake face 28 may also be a straight line shape inclined relative to the reference plane BF in a cross section orthogonal to the outer edge 12p of the upper surface 12 in a manner approaching the reference plane BF as it moves away from the land surface 26. The so-called reference plane BF is an imaginary plane located between the upper surface 12 and the lower surface 14 and orthogonal to the center axis CS of the insert. Figure 4 IVB Figure 5 VB, Figure 6 IVB Figure 7 VIIB and Figure 8 In FIG. VIIIB, the main rake face 28 is shown in bold and is a straight line in each cross-sectional view.

[0038] like Figures 1 to 3 As shown in the example, the upper surface 12 may also have a connecting surface 30 provided along the main rake face 28 at a position closer to the inside than the main rake face 28. The connecting surface 30 may function as a rake face. The connecting surface 30 may be connected to the main rake face 28. The connecting surface 30 may also be a shape that is recessed toward the reference plane BF in a cross section orthogonal to the outer edge 12p of the upper surface 12.

[0039] like Figures 1 to 3 As shown in the example, the upper surface 12 may also have a rising surface 32 provided along the connecting surface 30 at a position closer to the inside than the connecting surface 30. The rising surface 32 may have a function of curling the chips and improving the chip discharge performance. The rising surface 32 may be connected to the connecting surface 30. The rising surface 32 may also be inclined relative to the reference plane BF in a cross section orthogonal to the outer edge 12p of the upper surface 12 so as to be away from the reference plane BF as it is away from the connecting surface 30.

[0040] like Figure 1 and Figure 2 As shown in the example, the upper surface 12 may also have an upper end surface (convex surface) 34 surrounding an opening of the mounting hole 18. The upper end surface 34 may also be orthogonal to the blade center axis CS. The upper end surface 34 may be connected to the rising surface 32 at a position closer to the inside than the rising surface 32.

[0041] like Figure 2As shown in the example, the land surface 26 and the upper end surface 34 can be respectively symmetrical with respect to the blade center line CL. The main rake face 28, the connecting surface 30 and the rising surface 32 can be respectively arranged symmetrically with respect to the blade center line CL. The blade center line CL refers to an imaginary line passing through the vertices of the two first corners 20 and the blade axis CS when viewed from above.

[0042] like Figure 1 and Figure 2 As shown in the example, the cutting edge E may include a first cutting edge Ea located at the first corner 20 and a second cutting edge Eb located at the side portion 24. The first cutting edge Ea may be located at the entire first corner 20, or may be located at a portion of the first corner 20. The second cutting edge Eb may be located at the entire side portion 24, or may be located at a portion of the side portion 24.

[0043] like Figure 3 , Figure 4 VIA Figure 5 VA Figure 6 VIA Figure 7 VIIA and Figure 8 As shown in the example of FIG. VIIIA, the land surface 26 may include a first land surface 36 disposed along the first corner 20 and a second land surface 38 disposed along the edge 24. The land surface 26 may also include a third land surface 40 disposed between the first land surface 36 and the second land surface 38 and along the edge 24. Figure 5 VA and VB illustrate the boundary between the first land surface 36 and the third land surface 40 .

[0044] like Figure 3 , Figure 4 IVA Figure 4 IVB Figure 5 VA and Figure 5 As in the example shown in VB, the first land surface 36 may have a first straight portion 36s in a straight line shape in a cross section orthogonal to the first corner 20 (a cross section orthogonal to the outer edge 12p of the upper surface 12). In the cross section orthogonal to the first corner 20, the first straight portion 36s of the first land surface 36 may be inclined relative to the reference plane BF in a manner approaching the reference plane BF as it moves away from the first corner 20. In addition, the first land surface 36 may also have a first arc portion 36c, which is in an arc shape in the cross section orthogonal to the first corner 20. The first arc portion 36c of the first land surface 36 may be connected to the side surface 16. Figure 4 IVB and Figure 5 At VB, the first straight line portion 36s of the first land surface 36 is emphasized in the drawing using a thick line.

[0045] In the cross section orthogonal to the first corner 20, the inclination angle θ1 of the first straight portion 36s of the first land surface 36 relative to the imaginary plane VF orthogonal to the insert center axis CS can be smaller than the inclination angle α1 of the main rake face 28. In addition, the width T1 of the first land surface 36 in the direction orthogonal to the first corner 20 can increase as it approaches the edge 24 when viewed from above. The length M1 of the first straight portion 36s of the first land surface 36 in the cross section orthogonal to the first corner 20 can also increase as it approaches the edge 24. It should be noted that the reference plane BF is orthogonal to the insert center axis CS, so the imaginary plane VF is parallel to the reference plane BF. Therefore, for example, the inclination angle θ1 can be replaced by the inclination angle of the first straight portion 36s relative to the reference plane BF.

[0046] like Figure 3 , Figure 7 VIIA Figure 7 VIIB, Figure 8 VIIIA and Figure 8 As shown in the example of FIG. VIIIB, the entire second land surface 38 may be a convex curve shape protruding upward in a cross section orthogonal to the side portion 24 (a cross section orthogonal to the outer edge 12p of the upper surface 12). The second land surface 38 may have a second arc portion 38c, which is an arc shape in a cross section orthogonal to the side portion 24. The second arc portion 38c of the second land surface 38 may be connected to the side surface 16.

[0047] The width T2 of the second land surface 38 in the direction orthogonal to the edge 24 may increase as it moves away from the first corner 20 in a plan view. The second arc portion 38c of the second land surface 38 may be connected to the side surface 16. The curvature radius R1 of the first arc portion 36c of the first land surface 36 and the curvature radius R2 of the second arc portion 38c of the second land surface 38 may be the same. The two curvature radii R1 and R2 are the same in consideration of manufacturing errors, etc., and the difference between the two curvature radii R1 and R2 is within the range of ±5% of the average value of the two curvature radii R1 and R2.

[0048] like Figure 3 , Figure 5 VA Figure 5 VB, Figure 6 VIA and Figure 6As in the example shown in VIB of FIG, the third land surface 40 may have a second straight portion 40s in a straight line shape in a cross section orthogonal to the edge 24 (a cross section orthogonal to the outer edge 12p of the upper surface 12). The second straight portion 40s of the third land surface 40 may be inclined relative to the reference plane BF in a cross section orthogonal to the edge 24 so as to approach the reference plane BF as it moves away from the edge 24. In addition, the third land surface 40 may have a third arc portion 40c, which is in an arc shape in the cross section orthogonal to the edge 24. The third arc portion 40c of the third land surface 40 may be connected to the side surface 16. Figure 5 VB and Figure 6 At VIB of FIG. 1 , the second straight line portion 40s of the third land surface 40 is shown in bold.

[0049] In the cross section orthogonal to the edge 24, the inclination angle θ2 of the second straight portion 40s of the third cutting edge 40 relative to the imaginary plane VF orthogonal to the insert center axis CS can be smaller than the inclination angle α2 of the main rake face 28. The width T3 of the third cutting edge 40 in the direction orthogonal to the edge 24 can be constant when viewed from above. The length M2 of the second straight portion 40s of the third cutting edge 40 in the cross section orthogonal to the edge 24 can also be constant. It should be noted that, as described above, the imaginary plane VF is parallel to the reference plane BF. Therefore, for example, the inclination angle θ2 can be replaced by the inclination angle of the second straight portion 40s relative to the reference plane BF.

[0050] The curvature radius R1 of the first arc portion 36c of the first land surface 36, the curvature radius R2 of the second arc portion 38c of the second land surface 38, and the curvature radius R3 of the third arc portion 40c of the third land surface 40 may be the same. The three curvature radii R1, R2, and R3 are the same because the maximum difference between the three curvature radii R1, R2, and R3 is within the range of ±5% of the average value of the three curvature radii R1, R2, and R3 in consideration of manufacturing errors.

[0051] like Figure 1 and Figure 2 As shown in the example, as the material of the cutting insert 10, for example, cemented carbide and cermet can be cited. As the composition of cemented carbide, for example, there are WC-Co generated by adding cobalt (Co) powder to tungsten carbide (WC) and sintering, WC-TiC-Co generated by adding titanium carbide (TiC) to WC-Co, and WC-TiC-TaC-Co generated by adding tantalum carbide (TaC) to WC-TiC-Co. In addition, cermet is a sintered composite material composed of a metal and a ceramic component, and specifically, a sintered composite material having titanium compounds such as titanium carbide (TiC) and titanium nitride (TiN) as the main component can be cited.

[0052] The surface of the cutting insert 10 may be coated with a film by chemical vapor deposition (CVD) or physical vapor deposition (PVD). Examples of the composition of the film include titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and aluminum oxide (Al2O3).

[0053] According to the example of the embodiment of the present disclosure, the first land surface 36 is provided along the first corner 20 located near the machined surface of the workpiece W. Furthermore, the first land surface 36 has a first straight line portion 36s in a straight line shape in a cross section orthogonal to the first corner 20. Therefore, according to the example of the embodiment of the present disclosure, the first cutting edge Ea of the cutting edge E can be sharpened, the sharpness of the cutting edge E can be improved, and the surface accuracy of the workpiece W can be improved.

[0054] According to the example of the embodiment of the present disclosure, the second land surface 38 is provided along the edge 24 which is away from the processing surface of the workpiece W and plays a major role in the cutting process of the workpiece W. Furthermore, the entire second land surface 38 is a convex curve shape in a cross section orthogonal to the edge 24. Therefore, according to the example of the embodiment of the present disclosure, the cutting edge E is less likely to be damaged, and the durability of the cutting insert 10 can be improved.

[0055] That is, according to the example of the embodiment of the present disclosure, it is possible to achieve both improvement in the surface accuracy of the workpiece W and improvement in the durability of the cutting insert 10 .

[0056] When the first straight portion 36s of the first land surface 36 approaches the reference plane BF as it moves away from the first corner 20 in a cross section perpendicular to the first corner 20, the first cutting edge Ea can be made sharper, the sharpness of the cutting edge E can be further improved, and the surface accuracy of the workpiece W can be further improved.

[0057] In the cross section orthogonal to the first corner 20, when the inclination angle θ1 of the first straight portion 36s of the first blade surface 36 is smaller than the inclination angle α1 of the main front cutting edge 28, the tip strength of the cutting edge E, especially the tip strength of the first cutting edge Ea, can be fully improved, and space for chip flow can be ensured, thereby controlling the flow of chips.

[0058] When the curvature radius R1 of the first arc portion 36c of the first land surface 36 and the curvature radius R2 of the second arc portion 38c of the second land surface 38 are the same, the deviation of the sharpness of the cutting edge E is reduced, and the surface accuracy of the workpiece W is further improved. In particular, when the curvature radius R1 of the first arc portion 36c of the first land surface 36, the curvature radius R2 of the second arc portion 38c of the second land surface 38, and the curvature radius R3 of the third arc portion 40c of the third land surface 40 are the same, the deviation of the sharpness of the cutting edge E can be sufficiently reduced, and the surface accuracy of the workpiece W can be further improved.

[0059] When the width T1 of the first land surface 36 in the direction perpendicular to the first corner 20 increases as it approaches the edge 24, the portion of the first cutting edge Ea away from the second cutting edge Eb can be made sharper, and the sharpness of the cutting edge E can be further improved, thereby further improving the surface accuracy of the workpiece W. In particular, when the length M1 of the first straight portion 36s of the first land surface 36 in the cross section perpendicular to the first corner 20 increases as it approaches the edge 24, the portion of the first cutting edge Ea away from the second cutting edge Eb can be made sharper, and the surface accuracy of the workpiece W can be further improved.

[0060] When the width T2 of the second land surface 38 in the direction perpendicular to the edge 24 changes as it moves away from the first corner 20, the further away from the first land surface 36 in the second land surface 38, the more it is possible to improve the edge strength of the cutting edge E. As a result, even in cutting with a large cutting height (cutting with a large amount of cutting), it is difficult to generate edge defects on the cutting edge E, and the durability of the cutting insert 10 can be further improved.

[0061] When the third land surface 40 has a second straight line portion 40s in a straight line shape in a cross section perpendicular to the side portion 24, it is possible to avoid a significant decrease in the sharpness of the cutting edge E even under the first machining condition using the first cutting edge Ea and the second cutting edge Eb, as compared to a case where the portion of the land surface 26 along the side portion 24 is entirely the second land surface 38. Thus, even under the first machining condition, the surface accuracy of the workpiece W can be improved.

[0062] When the width T3 of the third land surface 40 in the direction perpendicular to the edge 24 is constant, under the second machining condition in which the first land surface 36 and the third land surface 40 contribute to the flow control of the chips and the second land surface 38 does not contribute to the flow control of the chips, the flow direction of the chips is consistent on the third land surface 40. Thus, under the second machining condition, the flow of the chips on the third land surface 40 becomes dominant, the chips are less likely to be clogged on the land surface 26, and the discharge of the chips can be improved.

[0063] <Cutting tools>

[0064] Reference Fig. 9 The cutting tool 42 according to the embodiment of the present disclosure will be described. Fig. 9 1 is a schematic perspective view of a cutting tool 42 according to an embodiment of the present disclosure.

[0065] like Fig. 9As shown, the cutting tool 42 of the embodiment of the present disclosure can be a tool for turning processing in cutting processing. As turning processing, for example, outer diameter processing, grooving processing and cutting processing can be cited. The cutting tool 42 of the embodiment of the present disclosure can have a rod-shaped shank 44. The shank 44 can extend from its first end (front end) 44a toward the second end (rear end) 44b. The shank 44 is made of a metal material such as steel. The shank 44 can have a knife groove 46 located on the side of the first end 44a. The shank 44 can have a threaded hole opening in the knife groove 46.

[0066] The cutting tool 42 may include a cutting insert 10 located in a groove 46 of a shank 44. The cutting insert 10 is attached to the groove 46 of the shank 44 by screwing a clamp screw 48 passing through the mounting hole 18 of the cutting insert 10 into a threaded hole of the shank 44 for fastening.

[0067] In the present disclosure, the cutting tool 42 used for turning among cutting processes is exemplified, but a cutting tool used for milling among cutting processes may include the cutting insert 10 as a constituent element.

[0068] <Method for manufacturing machined product>

[0069] Reference Figures 10 to 12 A method for producing a machined product according to an embodiment of the present disclosure will be described. Figures 10 to 12 This is a schematic diagram for explaining a method for producing a machined product according to an embodiment of the present disclosure.

[0070] like Figures 10 to 12 As shown in the example, the method for manufacturing a cut workpiece of the embodiment of the present disclosure is a method for manufacturing a cut workpiece M as a cut workpiece W that has been cut, and includes a first step, a second step, and a third step. The so-called first step is a step of rotating the cut workpiece W around its axis S. The so-called second step is a step of making the cutting blade 10 of the cutting tool 42 contact the rotating cut workpiece W to cut the cut workpiece W. The so-called third step is a step of moving the cutting tool 42 away from the cut workpiece W. As the material of the cut workpiece W, for example, stainless steel, carbon steel, alloy steel, cast iron, and non-ferrous metals can be cited. In addition, the specific content of the method for manufacturing a cut workpiece of the embodiment is as follows.

[0071] First, the cutting tool 42 is mounted on the tool post of the lathe, and the workpiece W is mounted on the chuck of the lathe. Fig.10 As shown in the example, the chuck is rotated to rotate the workpiece W around its axis S (first step). Fig.11As shown in the example, the cutting tool 42 is moved in the direction of arrow D1 to approach the workpiece W, and the cutting tip 10 of the cutting tool 42 is brought into contact with the rotating workpiece W to cut the workpiece W (second step). Thus, a machined surface Wf can be formed on the workpiece W.

[0072] Then, if Fig.12 As shown in the example, by moving the cutting tool 42 in the direction of the arrow D2, the cutting tool 42 is moved away from the workpiece W (third step). As a result, the cutting process of the workpiece W is completed, and a machined product M can be manufactured as the workpiece W after the cutting process is completed. The cutting insert 10 of the cutting tool 42 has excellent cutting ability for the reasons described above, so it is possible to manufacture a machined product M with excellent processing accuracy.

[0073] When the cutting process is continued, the cutting blade 10 of the cutting tool 42 may be repeatedly brought into contact with different portions of the cutting tool W while the cutting material W is rotated. In the embodiment of the present disclosure, the cutting tool 42 is brought close to the cutting material W, but as long as the cutting tool 42 and the cutting material W are relatively close, the cutting material W may be brought close to the cutting tool 42. In this regard, the same is true when the cutting tool 42 is moved away from the cutting material W.

[0074] In one embodiment, (1) the cutting unit comprises: an upper surface; a lower surface located on the opposite side of the upper surface; a side surface located between the upper surface and the lower surface; and a cutting edge located at the intersection of the upper surface and the side surface. When an imaginary axis passing through the center of the upper surface and the center of the lower surface is taken as the insert center axis and an imaginary plane located between the upper surface and the lower surface and orthogonal to the insert center axis is taken as the reference plane, the upper surface comprises: an outer edge having a corner portion in a convex curve shape and a side portion in a straight line shape extending from the corner portion; a land surface arranged along the outer edge; and a main rake face arranged along the land surface, and in a cross section orthogonal to the outer edge, it becomes a straight line shape in a manner that it approaches the reference plane as it moves away from the land surface. The land surface comprises a first land surface arranged along the corner portion and a second land surface arranged along the side portion. The first land surface has a first straight line portion in a straight line shape in a cross section orthogonal to the corner portion. The entire second land surface has a convex curved line shape in a cross section perpendicular to the side portion.

[0075] (2) In the cutting insert according to (1), in a cross section perpendicular to the corner portion, a width of the first straight portion in a direction perpendicular to the corner portion may approach the reference plane as it moves away from the corner portion.

[0076] (3) In the cutting insert according to (2), in a cross section perpendicular to the corner portion, an inclination angle of the first straight portion with respect to a virtual plane perpendicular to the insert center axis may be smaller than an inclination angle of the main rake face.

[0077] (4) In any one of the cutting inserts described in (1) to (3), the first edge surface may further include a first arc portion, the first arc portion being connected to the side surface and being in an arc shape in a cross section orthogonal to the corner portion. The second edge surface may include a second arc portion, the second arc portion being connected to the side surface and being in an arc shape in a cross section orthogonal to the edge portion. The first arc portion may have the same radius of curvature as the second arc portion.

[0078] (5) In any one of the cutting inserts described in (1) to (4), the width of the first land surface in a direction perpendicular to the corner portion may increase as it approaches the side portion.

[0079] (6) In the cutting insert according to (5), a length of a first straight line portion in a cross section perpendicular to the corner portion may increase as it approaches the side portion.

[0080] (7) In any one of the cutting inserts described in (1) to (6), the width of the second land surface in a direction perpendicular to the side portion may increase as the width increases away from the corner portion.

[0081] (8) In any one of the cutting inserts described in (1) to (7), the land surface may further include a third land surface, the third land surface being disposed along the edge portion between the first land surface and the second land surface. The third land surface may include a second straight line portion having a straight line shape in a cross section orthogonal to the edge portion.

[0082] (9) In the cutting insert according to (8) above, the third land surface may have a constant width in a direction perpendicular to the side portion.

[0083] (10) A cutting tool comprising: a shank in a rod shape extending from a first end toward a second end and having a groove located on the first end side; and a cutting insert according to any one of (1) to (9) located in the groove.

[0084] (11) A method for producing a machined product comprising: a step of rotating a workpiece; a step of bringing the cutting tool of (10) into contact with the rotating workpiece; and a step of moving the cutting tool away from the workpiece.

[0085] The invention of the present disclosure has been described above based on the accompanying drawings and embodiments. However, the invention of the present disclosure is not limited to the aforementioned embodiments. That is, the invention of the present disclosure can be variously modified within the scope shown in the present disclosure, and the embodiments obtained by appropriately combining the technical solutions respectively disclosed in different embodiments are also included in the technical scope of the invention of the present disclosure. That is, it is hoped that it will be noted that as long as it is a person skilled in the art, it is easy to make various deformations or corrections based on the present disclosure. In addition, it is hoped that these deformations or corrections are included in the scope of the present disclosure.

[0086] Description of reference numerals:

[0087] 10 Cutting blades

[0088] 12 Upper surface

[0089] 12p outer edge

[0090] 14 Lower surface

[0091] 16 Side

[0092] 18 Mounting holes

[0093] 20 First corner (corner)

[0094] 22 Second corner (other corners)

[0095] 24 Edge

[0096] 26 Land surface

[0097] 28 Main rake face

[0098] 30 Connection surface

[0099] 32 Stand up surface

[0100] 34 Upper end surface

[0101] 36 First land surface

[0102] 36s First straight line

[0103] 36c First arc portion

[0104] 38 Second land surface

[0105] 38c Second arc portion

[0106] 40 Third land surface

[0107] 40s Second straight line

[0108] 40c Third arc part

[0109] 42 Cutting tools

[0110] 44 Handle

[0111] 46 Slots

[0112] 48 Clamping screw

[0113] E Cutting Edge

[0114] Ea First cutting edge

[0115] Eb Second cutting edge.

Claims

1. A cutting insert, wherein: The cutting insert comprises: upper surface; a lower surface located on an opposite side of the upper surface; a side surface located between the upper surface and the lower surface; and a cutting edge located at the intersection of the upper surface and the side surface, When an imaginary axis passing through the center of the upper surface and the center of the lower surface is taken as the insert center axis, and an imaginary plane located between the upper surface and the lower surface and orthogonal to the insert center axis is taken as the reference plane, The upper surface has: an outer edge having a convex curved corner portion and a straight line side portion extending from the corner portion; a land surface disposed along the outer edge; and a main rake face provided along the land surface and having a straight line shape in a cross section perpendicular to the outer edge so as to approach the reference surface as it moves away from the land surface, The land surface has a first land surface arranged along the corner portion and a second land surface arranged along the edge portion, The first land surface has a first straight line portion in a straight line shape in a cross section perpendicular to the corner portion, The entire second land surface has a convex curved line shape in a cross section perpendicular to the side portion.

2. The cutting insert according to claim 1, wherein The first straight line portion approaches the reference plane as it moves away from the corner portion in a cross section perpendicular to the corner portion.

3. The cutting insert according to claim 2, wherein: In a cross section perpendicular to the corner portion, an inclination angle of the first straight portion with respect to an imaginary plane perpendicular to the insert center axis is smaller than an inclination angle of the main rake face.

4. The cutting insert according to any one of claims 1 to 3, wherein The first land surface further has a first arc portion, which is connected to the side surface and has an arc shape in a cross section orthogonal to the corner portion. The second land surface has a second arc portion, which is connected to the side surface and has an arc shape in a cross section perpendicular to the side portion. The curvature radius of the first arc portion is the same as the curvature radius of the second arc portion.

5. The cutting insert according to any one of claims 1 to 4, wherein The width of the first land surface in a direction perpendicular to the corner portion increases as it approaches the side portion.

6. The cutting insert according to claim 5, wherein: The length of the first straight line portion in the cross section perpendicular to the corner portion increases as it approaches the side portion.

7. The cutting insert according to any one of claims 1 to 6, wherein The width of the second land surface in the direction perpendicular to the side portion increases as it becomes farther away from the corner portion.

8. The cutting insert according to any one of claims 1 to 7, wherein The land surface further comprises a third land surface, the third land surface being arranged along the edge between the first land surface and the second land surface, The third land surface has a second straight line portion having a straight line shape in a cross section perpendicular to the side portion.

9. The cutting insert according to claim 8, wherein: The third land surface has a constant width in a direction perpendicular to the side portion.

10. A cutting tool, wherein: The cutting tool has: a knife handle in the shape of a rod extending from a first end toward a second end and having a knife groove located on the side of the first end; and The cutting insert according to any one of claims 1 to 9, which is located in the groove.

11. A method for manufacturing a machined product, wherein: The method for manufacturing the machined product comprises: The process of rotating the workpiece; a step of bringing the cutting tool according to claim 10 into contact with the rotating workpiece; and The step of moving the cutting tool away from the workpiece.

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