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

Abstract

The cutting insert according to one non-limiting aspect of the present disclosure has an upper surface, a lower surface, a side surface, and an upper cutting edge. The upper surface has a first corner, a second corner, a first side, a second side located opposite the first side, and a first land surface located along the first side. The side surface has a first side surface connected to the first side. The first side is formed in a projecting shape protruding outward as viewed from above, and has an apex part farthest from the second side. The first land surface has a first region that narrows with increasing distance from the first corner, and a second region located on the second corner side relative to the first region, and which widens with increasing distance from the first corner. The boundary between the first region and the second region is located close to the second corner relative to the apex part.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2021-166569, filed on October 11, 2021, the entire disclosure of which is incorporated herein by reference. [Technical Field]

[0002] The present disclosure generally relates to a cutting insert, a cutting tool, and a method for manufacturing a machined product used in cutting a workpiece, and more particularly to a cutting tool used in milling. [Background technology]

[0003] Known cutting inserts used in cutting workpieces such as metals include those described in Japanese Patent Laid-Open No. 2007-125669 (Patent Document 1), Japanese Patent Laid-Open No. 2008-511464 (Patent Document 2), and Japanese Patent Laid-Open No. 2017-056552 (Patent Document 3). The cutting inserts described in Patent Documents 1 to 3 each have an upper surface, a lower surface, a side surface, and an upper cutting edge. When the cutting insert is attached to a holder, a portion of the side surface of the cutting insert abuts against the holder.

[0004] There was a demand for cutting inserts that were durable and had high surface accuracy of the machined surface. Summary of the Invention

[0005] A non-limiting one-sided cutting insert of the present disclosure has a polygonal upper surface, a lower surface located opposite the upper surface, a side surface located between the upper surface and the lower surface, and an upper cutting edge located at the intersection of the upper surface and the side surface. The upper surface has a first corner, a second corner, a first side connected to the first corner and the second corner and inclined so as to approach the lower surface from the end connected to the first corner to the end connected to the second corner, a second side located opposite the first side, and a first land surface located along the first side. The side surface has a first side surface connected to the first side.

[0006] The first side has a convex shape that protrudes outward in a top view and has an apex that is farthest from the second side. The first land surface has a first region that narrows in width with increasing distance from the first corner, and a second region that is located closer to the second corner than the first region and widens in width with increasing distance from the first corner. The boundary between the first region and the second region is located closer to the second corner than the apex. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of a non-limiting single-sided cutting insert of the present disclosure. [Figure 2] FIG. 2 is a top view of the cutting insert shown in FIG. 1 . [Figure 3] FIG. 3 is the same top view as that of the cutting insert shown in FIG. 2. [Figure 4] 2 is a bottom view of the cutting insert shown in FIG. 1 as viewed from below. FIG. [Figure 5] FIG. 3 is a side view of the cutting insert shown in FIG. 2 as viewed from the A1 direction. [Figure 6] FIG. 3 is a side view of the cutting insert shown in FIG. 2 as viewed from the A2 direction. [Figure 7] FIG. 3 is a side view of the cutting insert shown in FIG. 2 as viewed from the A3 direction. [Figure 8] FIG. 1 is a perspective view of a non-limiting one-sided cutting tool of the present disclosure. [Figure 9] FIG. 9 is a side view of the cutting tool shown in FIG. 8. [Figure 10] FIG. 9 is an enlarged view of an area B1 shown in FIG. [Figure 11] 1 is a schematic diagram showing a step in a non-limiting method of manufacturing a one-sided machined product according to the present disclosure. [Figure 12] 1 is a schematic diagram showing a step in a non-limiting method of manufacturing a one-sided machined product according to the present disclosure. [Figure 13] 1 is a schematic diagram showing a step in a non-limiting method of manufacturing a one-sided machined product according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] <Cutting insert> Hereinafter, a non-limiting one-sided cutting insert 1 (hereinafter, sometimes referred to as "insert 1") 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 main components necessary for explaining the embodiment in a simplified form. Therefore, the insert 1 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 component.

[0009] The insert 1 may have an upper surface 3, a lower surface 5, a side surface 7, and an upper cutting edge 9, as shown in a non-limiting example in FIGS. 1 to 7. The upper surface 3 and the lower surface 5 are expressions for convenience and do not indicate an upward or downward direction. For example, the upper surface 3 does not need to face upward when the insert 1 is used. These points also apply to other portions including expressions of upper and lower.

[0010] The upper surface 3 may be polygonal. The lower surface 5 may be located on the opposite side of the upper surface 3. The lower surface 5 may also be polygonal like the upper surface 3. The insert 1 may be polygonal plate-shaped.

[0011] Examples of polygonal shapes include triangles, quadrilaterals, pentagons, hexagons, and octagons. For example, as shown in a non-limiting example in FIG. 1, the upper surface 3 may be rectangular. Note that a polygonal shape does not necessarily have to be a strict polygonal shape. For example, the multiple sides of the upper surface 3 do not have to be strictly straight lines, and may be curved when viewed from the front (top) of the upper surface 3. Furthermore, corners of the upper surface 3 located between adjacent sides do not have to be strictly corners. In other words, the multiple corners of the upper surface 3 do not have to be strictly corners. When viewed from above, the corners may have a convex curved shape, or may have a shape that combines straight lines and curves. The same applies to the lower surface 5.

[0012] An imaginary line passing through the center of the upper surface 3 and the center of the lower surface 5 may be the central axis O1 of the insert 1. If the upper surface 3 is polygonal, diagonal corners of the upper surface 3 may be connected by lines, and the intersection of these lines may be defined as the center of the upper surface 3. The starting point of the diagonal line may be the point where extensions of each side constituting the polygonal shape intersect. Also, the center of the upper surface 3 may be the position of the center of gravity of the upper surface 3 when viewed from above. The center of the lower surface 5 may be defined in the same way as the center of the upper surface 3.

[0013] The upper surface 3 may be rotationally symmetric by 180° about the central axis O1 when viewed from above. The lower surface 5 may be rotationally symmetric by 180° about the central axis O1 when viewed from the front (bottom).

[0014] The lower surface 5 may have a flat area 11 located in the center of the lower surface 5, as shown in a non-limiting example in Fig. 4. The flat area 11 can function as a bearing surface. That is, when a machined product is manufactured using the upper cutting edge 9, the flat area 11 can abut (contact) against the holder when the insert 1 is attached to the holder.

[0015] The flat surface region 11 may be a flat surface region. Flat does not necessarily have to be flat in the strict sense. The flat surface region 11 may be generally flat, and may be slightly curved or have slight irregularities that are not noticeable when the insert 1 is viewed as a whole. For example, the flat surface region 11 may have slight irregularities of about several tens of μm.

[0016] The planar region 11 may be positioned so as to include the central axis O1. The planar region 11 may also be perpendicular to the central axis O1. The term "perpendicular" does not necessarily mean strictly perpendicular, but may mean that the range of about 90°±5° is acceptable.

[0017] The insert 1 is not limited to a specific size. For example, the maximum width of the upper surface 3 when viewed from above may be set to approximately 4 to 25 mm. The height from the upper surface 3 to the lower surface 5 may be set to approximately 5 to 20 mm. The height from the upper surface 3 to the lower surface 5 may refer to the maximum distance between the upper surface 3 and the lower surface 5 in a direction parallel to the central axis O1. The height from the upper surface 3 to the lower surface 5 may also be rephrased as the width of the side surface 7 in the direction along the central axis O1.

[0018] The side surface 7 may be located between the upper surface 3 and the lower surface 5. The side surface 7 may be connected to the upper surface 3 and the lower surface 5, as shown in non-limiting examples in Figures 6 and 7.

[0019] The upper cutting edge 9 may be located at the intersection of the top surface 3 and the side surface 7. The upper cutting edge 9 can be used to cut a workpiece when manufacturing a machined product using the insert 1. The intersection of the top surface 3 and the side surface 7 where the upper cutting edge 9 is located is linear macroscopically, but may have a slight width microscopically. For example, the intersection of the top surface 3 and the side surface 7 may be honed, so that the top surface 3 and the side surface 7 are connected by a convex curved surface. In this case, in a cross section intersecting the top surface 3 and the side surface 7, the upper cutting edge 9 is represented microscopically as a convex curve rather than a point. When the upper cutting edge 9 has a slight width microscopically in this way, the durability of the upper cutting edge 9 is high.

[0020] The upper cutting edge 9 may be located over the entire intersection, or may be located over only a portion of the intersection. The upper cutting edge 9 may have a straight or curved shape when the side surface 7 is viewed from the front (side). Furthermore, the upper cutting edge 9 may have a shape that combines straight and curved lines when viewed from the side.

[0021] When the insert 1 has an upper cutting edge 9, one of the top surface 3 and the side surface 7 may have a rake face region, and the other of the top surface 3 and the side surface 7 may have a flank face region. As a non-limiting example shown in FIG. 1 , the top surface 3 may have a rake face region and the side surface 7 may have a flank face region.

[0022] The insert 1 may have a lower cutting edge 13. The lower cutting edge 13 may be located at the intersection of the lower surface 5 and the side surface 7. Like the upper cutting edge 9, the lower cutting edge 13 can be used to cut a workpiece when the insert 1 is used to manufacture a machined product.

[0023] The lower cutting edge 13 may be located at the entire intersection, or may be located at only a portion of the intersection. The lower cutting edge 13 may have a straight or curved shape when viewed from the side. The lower cutting edge 13 may also have a shape that combines straight and curved lines when viewed from the side. When the insert 1 has an upper cutting edge 9 and a lower cutting edge 13, the insert 1 may be double-sided.

[0024] The multiple corners on the top surface 3 may include a first corner 15 and a second corner 17. Furthermore, the multiple sides on the top surface 3 may include a first side 19 and a second side 21. That is, the top surface 3 may have the first corner 15, the second corner 17, the first side 19, and the second side 21.

[0025] 6, the first side 19 may be connected to the first corner 15 and the second corner 17, and may be inclined so as to approach the lower surface 5 from the end 19a connected to the first corner 15 toward the end 19b connected to the second corner 17. The second side 21 may be located on the opposite side of the first side 19. The second side 21 may be located on the opposite side of the first side 19 with respect to the central axis O1.

[0026] The first side 19 and the second side 21 may have the same length or different lengths. As a non-limiting example shown in Figure 1, the first side 19 and the second side 21 may have the same length. The first side 19 and the second side 21 may each be one of the long sides of the rectangular top surface 3.

[0027] The side surface 7 may have a first side surface 23. The first side surface 23 may be connected to the first edge 19. Furthermore, the side surface 7 may further have a second side surface 25 in addition to the first side surface 23. The second side surface 25 may be connected to the second edge 21.

[0028] The insert 1 may have through holes 27 that open in the first side surface 23 and the second side surface 25. The through holes 27 can be used, for example, to insert screws when fixing the insert 1 to a holder. Note that, instead of screws, for example, clamp members may be used when fixing the insert 1 to a holder. The first side surface 23 and the second side surface 25 may each have flat regions in their central portions. The through holes 27 may be located in these flat regions.

[0029] The through hole 27 may open at the center of the first side surface 23 and the center of the second side surface 25. The centers of the first side surface 23 and the second side surface 25 may be defined in the same way as the center of the top surface 3. An imaginary line passing through the center of the first side surface 23 and the center of the second side surface 25 may be the central axis O2 of the through hole 27. The central axis O2 of the through hole 27 may be perpendicular to the central axis O1 of the insert 1. Note that the through hole 27 is not limited to a configuration in which it opens at the first side surface 23 and the second side surface 25. The through hole 27 may open at the top surface 3 and the bottom surface 5, for example.

[0030] The upper surface 3 may have a land surface. The land surface may refer to a narrow, band-shaped surface area located along a side of the upper surface 3. The land surface may be used to increase the durability of the upper cutting edge 9. In a cross section of the upper surface 3 perpendicular to the side, the land surface is an area represented by a straight line close to the side. When the upper cutting edge 9 is represented by a dot in a cross section intersecting the upper surface 3 and the side surface 7, the land surface is a linear area extending from the upper cutting edge 9 represented by the dot toward the center of the upper surface 3. When the upper cutting edge 9 is represented by a convex curve in a cross section intersecting the upper surface 3 and the side surface 7, the land surface is a linear area extending from the upper cutting edge 9 represented by the convex curve toward the center of the upper surface 3.

[0031] As described above, when the top surface 3 has a rake face region, the boundary between the land surface and the rake face region is shown macroscopically as a bent portion. That is, in a cross section intersecting the top surface 3 and the side surface 7, the inner end of the linear region corresponding to the land surface becomes the inner end of the land surface.

[0032] Here, the upper surface 3 may have a first land surface 29, as in a non-limiting example shown in Fig. 1. The first land surface 29 may be located along the first side 19. Furthermore, the first side 19 may have a convex shape that protrudes outward in top view, and may have an apex 31 that is farthest from the second side 21, as in a non-limiting example shown in Figs. 2 and 3.

[0033] The width W1 of the first land surface 29 located along such a first side 19 may not be constant. Specifically, the first land surface 29 may have a first region 33 and a second region 35. In the first region 33, the width W11 of the first land surface 29 may become narrower with increasing distance from the first corner 15. The second region 35 may be located closer to the second corner 17 than the first region 33, and the width W12 of the first land surface 29 in the second region 35 may become wider with increasing distance from the first corner 15.

[0034] The width of the first land surface 29 is narrower at a boundary 37 between the first region 33 and the second region 35. Therefore, the portion of the upper cutting edge 9 along the boundary 37 is relatively sharp and can function as a so-called wiper edge. The boundary 37 between the first region 33 and the second region 35 may be located closer to the second corner 17 than to the apex 31. In other words, the distance L11 between the second corner 17 and the boundary 37 may be smaller than the distance L12 between the second corner 17 and the apex 31.

[0035] When the first side 19 has a convex shape in a top view, cutting loads tend to concentrate on the apex 31 of the first side 19. Furthermore, at the boundary 37 between the first region 33 and the second region 35, the width W1 of the first land surface 29 is smallest, and therefore durability tends to be lowest. When the boundary 37 is located closer to the second corner 17 than the apex 31, the position of the apex 31, where cutting loads tend to concentrate, is shifted from the position of the boundary 37, where durability tends to be lowest, making it easy to avoid excessive reduction in durability.

[0036] Furthermore, since the boundary 37 is located closer to the second corner 17 than the apex 31, it is easy to improve the surface precision of the machined surface even in high-depth cutting where the first side 19 is used as a cutting edge closer to the second corner 17 than the apex 31. Therefore, the insert 1 has durability and provides high surface precision of the machined surface.

[0037] The first side 19 may have a convex curved shape in top view. Similarly, the second side 21 may have a convex curved shape in top view. The apex 31 may be the outermost portion of the first side 19 in top view. The apex 31 may be located at the center of the first side 19. In a non-limiting example shown in FIG. 2 , the second side 21 is located on the opposite side of the first side 19 with respect to the central axis O1, and the top surface 3 is rotationally symmetrical by 180° about the central axis O1 in top view. When the top surface 3 has such a configuration, the apex 31 may be located on an imaginary line passing through the center of the first side surface 23 and the center of the second side surface 25. In other words, the apex 31 may be located on the central axis O2 of the through hole 27 in top view.

[0038] However, when first side 19 has a convex curved shape in top view, it is intended that first side 19 is not a straight line in the strict sense. Furthermore, when multiple corners on top surface 3 have a convex curved shape in top view, it is intended that multiple corners including first corner 15 and second corner 17 are not corners in the strict sense. Therefore, when first side 19 and the multiple corners have a convex curved shape, the radius of curvature of first side 19 is several tens of times or more the radius of curvature of the multiple corners, so that top surface 3 is generally polygonal in the macroscopic sense. The same applies to second side 21.

[0039] As shown in a non-limiting example in FIG. 3 , the width W11 of the first land surface 29 in the first region 33 and the width W12 of the first land surface 29 in the second region 35 may be dimensions in a direction perpendicular to the first side 19. Furthermore, the configuration in which the width W11 narrows with increasing distance from the first corner 15 may mean that the width W11 does not widen with increasing distance from the first corner 15. Therefore, the width W11 may be partially constant. In other words, the first region 33 may include a region where the width W11 is constant. These points may also be defined similarly for the width W12. In other words, the configuration in which the width W12 widens with increasing distance from the first corner 15 may mean that the width W12 does not narrow with increasing distance from the first corner 15. Furthermore, the second region 35 may include a region where the width W12 is constant.

[0040] 2, the second region 35 may have an end 35a on the first corner 15 side connected to the first region 33. In this case, the first land surface 29 is continuous from the first region 33 to the second region 35. That is, the first land surface 29 is also present at a boundary 37 between the first region 33 and the second region 35. Therefore, the boundary 37 is less likely to have a sharp edge and is less likely to be chipped.

[0041] The second region 35 may have an end 35b on the second corner 17 side separated from the second corner 17. The upper cutting edge 9 does not have to be located between the end 35b and the second corner 17. The first region 33 may have an end 33a on the first corner 15 side connected to the first corner 15.

[0042] The second corner 17 may be located closer to the boundary 37 than the first corner 15. In other words, as in a non-limiting example shown in Figure 3, the distance L11 between the second corner 17 and the boundary 37 may be smaller than the distance L2 between the first corner 15 and the boundary 37. In this case, it is easy to improve the surface precision of the machined surface even in high-depth cutting where the first side 19 is used as a cutting edge up to a point closer to the second corner 17 than the midpoint between the first corner 15 and the second corner 17.

[0043] The apex 31 may be located closer to the boundary 37 than the second corner 17. In other words, the distance L3 between the apex 31 and the boundary 37 may be smaller than the distance L11 between the second corner 17 and the boundary 37. When the distance L3 is larger than the distance L11, the range of cutting heights at which the apex 31 contacts the workpiece while the boundary 37 does not contact the workpiece is wider. However, when the distance L3 is smaller than the distance L11, the range of cutting heights at which the apex 31 and the boundary 37 contact the workpiece is wider. In other words, the range of cutting heights at which the portion of the upper cutting edge 9 along the boundary 37 can function as a wiper edge is wider.

[0044] The maximum value of the width W11 of the first land surface 29 in the first region 33 may be the same as or different from the maximum value of the width W12 of the first land surface 29 in the second region 35. For example, as in the non-limiting example shown in Figure 3, when the maximum value of the width W11 is the same as the maximum value of the width W12, variation in the wear of the rake face is likely to be suppressed. Therefore, variation in the chip control performance and the decrease in the strength of the upper cutting edge 9 is likely to be suppressed.

[0045] Note that the maximum value of the width W11 being the same as the maximum value of the width W12 does not necessarily mean that the two values ​​are exactly the same. For example, there may be a difference of about 10% between the two values. Furthermore, the end 33a of the first region 33 on the first corner 15 side may have the maximum value of the width W11 of the first land surface 29 in the first region 33. The end 35b of the second region 35 on the second corner 17 side may have the maximum value of the width W12 of the first land surface 29 in the second region 35.

[0046] The top surface 3 may further include a third side 39 and a second land surface 41, as shown in a non-limiting example in Figure 2. The third side 39 may be connected to the first corner 15 on the side opposite to the first side 19. The second land surface 41 may be located along the third side 39.

[0047] The maximum value of the width W2 of the second land surface 41 may be the same as or different from the maximum value of the width W1 of the first land surface 29. For example, as in a non-limiting example shown in Fig. 3, the maximum value of the width W2 may be greater than the maximum value of the width W1. In this case, it is easy to increase the durability of the third edge 39 in machining such as plunge machining, in which the third edge 39 is used as a cutting edge.

[0048] The width W2 of the second land surface 41 may be constant or may vary. For example, as in the non-limiting example shown in Figure 3, when the width W2 is constant, the degree of freedom in cutting processing is likely to be increased. For example, stable chipping resistance can be ensured even in processing where the lateral cutting depth varies, such as plunge processing.

[0049] The width W1 of the first land surface 29 and the width W2 of the second land surface 41 are not limited to a specific size. For example, the maximum value of the width W1 of the first land surface 29 may be set to approximately 0.05 to 0.35 mm. Furthermore, the maximum value of the width W2 of the second land surface 41 may be set to approximately 0.1 to 0.4 mm. When the width W2 of the second land surface 41 varies, the end of the second land surface 41 farther from the first corner 15 may have the maximum value of the width W2 of the second land surface 41.

[0050] 2, the third side 39 may be shorter than the first side 19 and the second side 21. The third side 39 may be one of the short sides of the rectangular top surface 3.

[0051] Examples of materials for the insert 1 include cemented carbide and cermet. Examples of cemented carbide compositions include WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co. Here, WC, TiC, and TaC may be hard particles, and Co may be a binder phase.

[0052] The cermet may also be a sintered composite material in which a ceramic component is combined with a metal. An example of a cermet is a titanium compound mainly composed of titanium carbide (TiC) or titanium nitride (TiN). It goes without saying that the material of the insert 1 is not limited to the above composition.

[0053] The surface of the insert 1 may be coated with a coating using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, and the composition of the coating may include, for example, titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and alumina (Al2O3).

[0054] <Cutting tools> Next, a non-limiting example of a cutting tool 101 according to the present disclosure will be described with reference to Figures 8 to 10. As shown in Figure 8 and other examples, the rotation axis O3 of the cutting tool 101 may be indicated by a two-dot chain line, and the rotation direction of the rotation axis O3 may be indicated by an arrow Y1.

[0055] The cutting tool 101 may have a holder 103 and an insert 1, as in a non-limiting example shown in Figures 8 to 10. When the cutting tool 101 has the insert 1, the insert 1 has durability and high surface precision of the machined surface, and therefore, excellent cutting performance can be exhibited.

[0056] The cutting tool 101 is rotatable around a rotation axis O3. The cutting tool 101 may also be used for milling.

[0057] The holder 103 may have a cylindrical shape extending from the first end 103a to the second end 103b along the rotation axis O3. The cylindrical shape may be roughly cylindrical, and does not necessarily have to be cylindrical in the strict sense.

[0058] The holder 103 may have a pocket 105 located on the side of the first end 103a. The insert 1 can be attached to the pocket 105. The pocket 105 may be open on the outer circumferential surface of the holder 103 and on the end surface on the side of the first end 103a.

[0059] The insert 1 may be located in the pocket 105. There may be only one pocket 105, or there may be multiple pockets 105. When the holder 103 has multiple pockets 105, the cutting tool 101 may have multiple inserts 1, and each pocket 105 may have one insert 1 located therein.

[0060] When the holder 103 has a plurality of pockets 105, these pockets 105 may be positioned at equal intervals around the rotation axis O3, or may be positioned at unequal intervals.

[0061] The insert 1 may be attached to the pocket 105 so that at least a part of the cutting edge protrudes from the holder 103. For example, the insert 1 may be attached to the holder 103 so that the upper cutting edge 9 protrudes from the holder 103 toward the workpiece. In this case, the lower surface 5 and the side surface 7 may abut against the holder 103.

[0062] The insert 1 may also be attached to the holder 103 so that the first corner 15 is closer to the first end 103a than the second corner 17, and the first side 19 is closer to the outer periphery than the second side 21. In this case, the boundary 37 may be closer to the second end 103b than the apex 31.

[0063] The insert 1 may be attached to the pocket 105 by a screw 107. That is, the insert 1 may be attached to the holder 103 by inserting the screw 107 into the through hole 27 of the insert 1, inserting the tip of the screw 107 into a threaded hole formed in the pocket 105, and fixing the screw 107 in the threaded hole.

[0064] Examples of materials for the holder 103 include steel and cast iron. When the material for the holder 103 is steel, the holder 103 has high toughness.

[0065] <Method of manufacturing machined products> Next, a non-limiting method for manufacturing the one-surface machined product 201 according to the present disclosure will be described with reference to FIGS.

[0066] The machined product 201 may be produced by cutting a workpiece 203. A method for producing the machined product 201 may include the following steps: (1) rotating a cutting tool 101, such as the non-limiting embodiments described above; (2) contacting the rotating cutting tool 101 with the workpiece 203; (3) separating the cutting tool 101 from the workpiece 203; may also be provided.

[0067] Specifically, first, as shown in a non-limiting example in Fig. 11, the cutting tool 101 may be brought relatively closer to the workpiece 203 while being rotated in the Y1 direction around the rotation axis O3. Next, as shown in a non-limiting example in Fig. 12, the upper cutting edge 9 of the cutting tool 101 may be brought into contact with the workpiece 203 to cut the workpiece 203. Then, as shown in a non-limiting example in Fig. 13, the cutting tool 101 may be moved relatively away from the workpiece 203.

[0068] When the above steps are performed, it is possible to obtain a machined product 201 having a high surface accuracy of the machined surface.

[0069] In the non-limiting example shown in FIGS. 11 to 13, the workpiece 203 is fixed and the cutting tool 101 is moved in each step, but the present invention is not limited to this configuration.

[0070] For example, in step (1), the workpiece 203 may be brought closer to the cutting tool 101. Similarly, in step (3), the workpiece 203 may be moved away from the cutting tool 101. When continuing the cutting process, the cutting tool 101 may be kept rotating, and the step of bringing the upper cutting edge 9 of the insert 1 into contact with different locations on the workpiece 203 may be repeated.

[0071] Examples of the material of the workpiece 203 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals. [Explanation of symbols]

[0072] 1. Cutting insert (insert) 3...Top surface 5...Bottom surface 7. Side 9. Upper cutting edge 11...plane area 13...Lower cutting edge 15...1st corner 17...Second corner 19...First side 19a...end 19b...end 21...Second side 23...1st side 25...Second side 27. Through hole 29. First land surface 31...Top 33...1st area 33a...end 35...Second area 35a...end 35b...end 37...boundary 39... Third side 41...Second land surface 101...Cutting tools 103 Holder 103a...1st end 103b...2nd end 105···Pocket 107···Screw 201...Cutting workpiece 203...Work material O1: Center axis of cutting insert O2: Center axis of the through hole O3 Rotation axis

Claims

1. A polygonal top surface; a lower surface located opposite the upper surface; a side surface located between the upper surface and the lower surface; an upper cutting edge located at an intersection of the upper surface and the side surface, The upper surface is The first corner, The second angle, a first side connected to the first corner and the second corner and inclined so as to approach the bottom surface from an end connected to the first corner to an end connected to the second corner; a second side located opposite the first side; a first land surface located along the first side, the side surface has a first side surface connected to the first edge, the first side has a convex shape that protrudes outward in a top view and has an apex that is farthest from the second side, The first land surface is a first region whose width narrows with increasing distance from the first corner; a second region located closer to the second corner than the first region and having a width that increases with increasing distance from the first corner; the boundary between the first region and the second region is located closer to the second corner than to the apex, the second corner is located closer to the boundary than the first corner; The boundary is located closer to the lower surface than to the top portion of the cutting insert.

2. The cutting insert according to claim 1 , wherein the apex is located closer to the boundary than the second corner.

3. The cutting insert according to claim 1 or 2, wherein a maximum value of a width of the first land surface in the first region is the same as a maximum value of a width of the first land surface in the second region.

4. The upper surface is a third side connected to the first corner on the opposite side to the first side; a second land surface located along the third side, The cutting insert according to claim 1 or 2, wherein a maximum value of a width of the second land surface is greater than a maximum value of a width of the first land surface.

5. The cutting insert according to claim 4 , wherein the second land surface has a constant width.

6. 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 the cutting insert according to claim 1 or 2 located in the pocket.

7. rotating the cutting tool of claim 6; bringing the rotating cutting tool into contact with a workpiece; and a step of separating the cutting tool from the workpiece.

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