Cutting insert, cutting tool, and method of manufacturing a machined workpiece

Abstract

A cutting insert of one aspect has a base portion and a cutting portion. The cutting portion has a rake face, a top surface, a first side surface, a second side surface, a front cutting edge, and a transverse cutting edge. The front cutting edge has a first cutting edge and a second cutting edge, the first cutting edge having a radius of curvature greater than a radius of curvature of the second cutting edge.

Description

TECHNICAL FIELD

[0001] The present application relates to a cutting insert, a cutting tool, and a manufacturing method of a cut work. BACKGROUND

[0002] As a cutting insert used when turning a workpiece such as a metal, for example, there is known a non-regrinding insert described in Patent Literature 1. The insert described in Patent Literature 1 can be used for plunge reverse horizontal machining. The insert has a main body portion and a cutting portion. The cutting portion has a circular-arc-shaped wiper edge at a front end thereof, a first cutting edge extending from the wiper edge, and a second cutting edge extending from the first cutting edge. The wiper edge has an effect of reducing the surface roughness of a machined surface of the workpiece.

[0003] PRIOR ART DOCUMENT

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2012-250296 SUMMARY

[0006] A cutting insert according to one aspect of the present application has a main body portion and a cutting portion provided in a manner projecting from the main body portion, the cutting portion having a front end surface at a front end side in a direction projecting from the main body portion, an upper surface extending from the main body portion to the front end surface, a first side surface extending from the main body portion to the front end surface and adjacent to the upper surface, a second side surface extending from the main body portion to the front end surface and adjacent to the upper surface at a side opposite to the first side surface, a front cutting edge at a position where the upper surface and the front end surface intersect, and a lateral cutting edge at a position where the upper surface and the first side surface intersect. The front cutting edge has a first cutting edge including an end portion of the front end side in the front cutting edge, and a second cutting edge between the first cutting edge and the lateral cutting edge, a radius of curvature of the first cutting edge being larger than a radius of curvature of the second cutting edge. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a perspective view of a cutting insert according to an embodiment of the present application.

[0008] Figure 2 is a perspective view of a cutting insert according to an embodiment of the present application. Figure 1

[0009] Figure 3 is a perspective view of a cutting insert according to an embodiment of the present application. Figure 1 Figure 1 is a plan view of a cutting insert according to an embodiment of the present application.

[0010] ​​Figure 4 is an enlarged view of the region B1 shown in FIG. 1. Figure 1

[0011] Figure 5 is an enlarged view of the region B2 shown in FIG. 1. Figure 2

[0012] Figure 6 is an enlarged view of the region B3 shown in FIG. 1 and an enlarged view of the tip portion of the cutting portion. Figure 3

[0013] Figure 7 is a schematic view showing the shape of a chip at the time of cutting.

[0014] Figure 8 is an A-A line cross-sectional view of the cutting insert shown in FIG. 1. Figure 6

[0015] is an enlarged view of the tip portion of the cutting portion shown in FIG. 1 rotated 90° clockwise. Figure 9 Figure 6

[0016] Figure 10 Figure 8

[0017] Figure 11 is a perspective view showing a cutting tool of an embodiment.

[0018] Figure 12 is an enlarged view of the region B4 shown in FIG. 1. Figure 10

[0019] Figure 13 is a schematic view showing one step of a manufacturing method of a cutting workpiece of an embodiment.

[0020] Figure 14 is a schematic view showing one step of a manufacturing method of a cutting workpiece of an embodiment.

[0021] Figure 15 is a schematic view showing one step of a manufacturing method of a cutting workpiece of an embodiment.

[0022] Figure 16 is a schematic view showing one step of a manufacturing method of a cutting workpiece of an embodiment. DETAILED DESCRIPTION

[0023] ​​​​​​​​Hereinafter, a method for manufacturing a cutting insert (hereinafter also simply referred to as an insert), a cutting tool, and a workpiece, which is an example embodiment of the present invention, will be described in detail using the accompanying drawings. However, for ease of explanation, the figures referred to below only show simplified main components necessary for illustrating the embodiments. Therefore, the insert and cutting tool may have any structural components not shown in the referenced figures. In addition, the dimensions of the components in the figures do not accurately represent the actual dimensions of the structural components or the dimensional ratios of each component.

[0024] The cutting tool of this embodiment can be used, for example, in turning operations. Examples of turning operations include: outer diameter machining, inner diameter machining, grooving, parting, and reverse cross-feed machining.

[0025] (1. Overview of the blade)

[0026] First, use Figures 1-3 A summary of the blade 1 according to one embodiment of the present invention will be described. Figure 1 This is a 3D view of blade 1. Figure 2 This is a three-dimensional view of blade 1 viewed from another direction. Figure 3 From Figure 1 The top view of blade 1 is shown in direction A1.

[0027] like Figures 1-3 As shown, the blade 1 includes a base portion 10 and a cutting portion 20 that protrudes from the base portion 10. The base portion 10 can be used to mount the blade 1 onto the tool holder 105 (described later). Figure 11 , Figure 12 The part constrained by the tool holder 105 during cutting. The cutting part 20 is the part that is machined in the cutting process described later, along with the workpiece 201 (see reference 105). Figures 13-16 The contact area is the part that plays a major role in the cutting process. In this example, the insert 1 has two cutting parts 20, but it may also have three or more cutting parts 20, or it may have only one cutting part 20.

[0028] The shape of the base portion 10 is not limited to a specific structure. For example, the shape of the base portion 10 can also be a rod shape, a polygonal plate shape, or a polygonal prism shape. In this example, such as Figures 1-3 As shown, viewed from the direction directly opposite the larger plate surface (first main surface 11), the base portion 10 is a hexagonal plate shape with the two opposite corners of a rectangle removed. The base portion 10 has: a first main surface 11 (refer to...) Figure 1 It is hexagonal; the second principal face 12 (refer to...) Figure 2) is hexagonal; a second main face 12 which is hexagonal and located on the opposite side of the first main face 11; and a through-hole 13 which is opened in the center of the first main face 11 and the center of the second main face 12. The through-hole 13 can also be used to fix the insert 1 to a shank 105 (refer to Figure 11 、 Figure 12 ) to be described later. For example, when the insert 1 is mounted to the shank 105, the insert 1 can be fixed to the shank 105 by inserting a screw 107 into the through-hole 13.

[0029] Further, in the present example, the base portion 10 has an upper side face 14 and a lower side face 15. The upper side face 14 and the lower side face 15 are flat faces which are arranged in parallel with each other along the longitudinal direction of the insert 1. As shown in Figure 1 、 Figure 2 , the upper side face 14 and the lower side face 15 can also constitute a part of the side face portion of the base portion 10 which is located between the first main face 11 and the second main face 12.

[0030] Note that, in the present specification, the description of "flat" or "plane" means that it is not a curved face in which the level can be visually confirmed, or does not have a concave-convex in which the level can be visually confirmed, and does not require strict flatness. Therefore, a concave-convex of an unavoidable degree can also be allowed in the manufacture of the insert 1. Specifically, a concave-convex having a surface roughness of about 50 μm can be present.

[0031] The size of the base portion 10 is not particularly limited. The maximum width of the base portion 10 in the direction from the first main face 11 orthogonal to the longitudinal direction of the insert 1 toward the second main face 12 can be set to about 2.9 to 4.1 mm, for example. Further, the dimension of the base portion 10 in the longitudinal direction can be set to about 8 to 20 mm, for example.

[0032] The shape of the two cutting portions 20 is not limited to a particular structure. The cutting portion 20 can be a structure of a bar shape, a polygonal plate shape, or a polygonal prism shape, for example. The shapes of the two cutting portions 20 in the present example are each a triangular plate shape. The base portion 10 and the cutting portion 20 in the insert 1 can be formed separately, or can be formed integrally.

[0033] The width of the cutting portion 20 in the direction from the first main face 11 orthogonal to the longitudinal direction of the insert 1 toward the second main face 12 can be smaller than the width of the base portion 10 in the direction. In the case where the width of the base portion 10 is relatively large, the wall thickness of the base portion 10 is ensured, and thus the insert 1 can be stably fixed to the shank 105 (refer to Figure 11 、 Figure 12Furthermore, when the width of the cutting portion 20 is relatively small, the degree of freedom in the machining width during the cutting of the workpiece 201 can be increased. It should be noted that when the widths of the base portion 10 and the cutting portion 20 are different as described above, the regions of the base portion 10 and the cutting portion 20 in the insert 1 can also be divided using the portion with the different widths.

[0034] In this example, two cutting portions 20 protrude outward from the base portion 10. One of the two cutting portions 20 protrudes outward from one end of the base portion 10 along its length direction. The other cutting portion 20 protrudes from the other end of the base portion 10 along its length direction. The two cutting portions 20 protrude to opposite sides.

[0035] In the insert 1, the two cutting portions 20 can also be arranged in a rotationally symmetrical manner with the central axis of the through hole 13 as a reference. In this example, the two cutting portions 20 protrude towards opposite sides and are arranged in a rotationally symmetrical manner with the central axis of the through hole 13 as a reference, and have approximately the same structure. Therefore, below, we will discuss the two cutting portions 20, in... Figure 1 The structure of the cutting part 20 protruding to the right when viewed from the first main surface 11 side of the base part 10 will be described in detail, while the description of the other cutting part 20 protruding to the left will be omitted.

[0036] (2. Detailed information about the cutting part)

[0037] Next, use Figures 4-6 The details of the cutting part 20 are explained. Figure 4 yes Figure 1 An enlarged view of region B1 shown. Figure 5 yes Figure 2 An enlarged view of region B2 shown.

[0038] like Figure 4 and Figure 5 As shown, in this example, the cutting portion 20 has an upper surface 21, a front end surface 22, a first side surface 23, a second side surface 24, and a lower surface 25. The front end surface 22 is located in the direction in which the cutting portion 20 protrudes from the base portion 10, i.e., the front end side.

[0039] The upper surface 21 extends from the base portion 10 (the upper side surface 14 of the base portion 10) to the front end surface 22 and is adjacent to the front end surface 22. It should be noted that if it is another cutting portion 20, the upper surface 21 extends from the lower side surface 15 of the base portion 10 to the front end surface 22.

[0040] The first side surface 23 extends from the base portion 10 to the front end surface 22. More specifically, the first side surface 23 extends from the second major surface 12 of the base portion 10 to the front end surface 22. In another cutting portion 20, the first side surface 23 extends from the second major surface 12 of the base portion 10 to the front end surface 22. The first side surface 23 is adjacent to the upper surface 21, and is also adjacent to the front end surface 22.

[0041] The second side surface 24 extends from the base portion 10 to the front end surface 22. More specifically, the second side surface 24 extends from the step surface 16 adjacent to the first major surface 11 of the base portion 10 to the front end surface 22. The step surface 16 is a flat surface extending in a direction from the first major surface 11 toward the second major surface 12. The step surface 16 is a surface generated when a width of the cutting portion 20 in a direction from the first major surface 11 toward the second major surface 12 is smaller than a width of the base portion 10 in the same direction. In another cutting portion 20, the second side surface 24 is also adjacent to the first major surface 11 of the base portion 10, and extends from a step surface which is a flat surface in a direction from the first major surface 11 toward the second major surface 12 to the front end surface 22. The second side surface 24 is adjacent to the upper surface 21 on an opposite side of the first side surface 23. In addition, the second side surface 24 is also adjacent to the front end surface 22 on the opposite side of the first side surface 23.

[0042] The lower surface 25 extends from the lower side surface 15 of the base portion 10 to the front end surface 22. If it is another cutting portion 20, the lower surface 25 extends from the upper side surface 14 of the base portion 10 to the front end surface 22. The lower surface 25 is adjacent to the upper surface 21 via the first side surface 23, the front end surface 22, and the second side surface 24.

[0043] In addition, as shown in the present example, the first side surface 23 is substantially flat. The front end surface 22 can be a gently curved surface, or can be substantially flat, as will be described in detail later. The front end surface 22 and the first side surface 23 can be directly connected, or can be connected via a curved surface between the front end surface 22 and the first side surface 23. In addition, the second side surface 24 is also substantially flat. The first side surface 23 and the second side surface 24 can also be curved surfaces. Figure 4 Figure 5 The surfaces such as the upper surface 21, the front end surface 22, the first side surface 23, and the second side surface 24 intersect with each other to form edges. Of these, an edge where the upper surface 21 intersects with the front end surface 22 is provided as a first edge E1, an edge where the upper surface 21 intersects with the first side surface 23 is provided as a second edge E2, and an edge where the upper surface 21 intersects with the second side surface 24 is provided as a third edge (edge) E3. That is, the cutting portion 20 has the first edge E1, the second edge E2, and the third edge E3. A cutting edge for cutting processing can be formed at the edges, and is located at the edges.

[0044] The surfaces such as the upper surface 21, the front end surface 22, the first side surface 23, and the second side surface 24 intersect with each other to form edges. Of these, an edge where the upper surface 21 intersects with the front end surface 22 is provided as a first edge E1, an edge where the upper surface 21 intersects with the first side surface 23 is provided as a second edge E2, and an edge where the upper surface 21 intersects with the second side surface 24 is provided as a third edge (edge) E3. That is, the cutting portion 20 has the first edge E1, the second edge E2, and the third edge E3. A cutting edge for cutting processing can be formed at the edges, and is located at the edges.

[0045] ​In the present example, the cutting portion 20 has a front cutting edge F at the first edge line El and a side cutting edge S at the second edge line E2. In contrast, the third edge line E3 does not have a cutting edge. Here, the third edge line E3 is an edge line at which a surface of the chip breaker protrusion 21d formed in the upper surface 21 intersects the second side surface 24.

[0046] The front cutting edge F can be used, for example, as a cutting edge that mainly functions in slotting and parting. The side cutting edge S can also be used as a cutting edge that assists cutting based on the front cutting edge F. The side cutting edge S can be used, for example, as a cutting edge that mainly functions in plunge reverse side milling (side milling). The front cutting edge F can also be used as a cutting edge that assists cutting based on the side cutting edge S, and specifically, can be used as a wiper edge (facing edge).

[0047] In the present example, the cutting portion 20 has a plurality of cutting edges as the front cutting edge F, and a plurality of inclined surfaces are formed in the upper surface 21 corresponding to the plurality of cutting edges. Hereinafter, the plurality of cutting edges and the plurality of inclined surfaces will be described with reference to Figure 6 and Figures 8-10 The plurality of cutting edges and the plurality of inclined surfaces will be described. Figure 6 Figure 3 is an enlarged view of the region B3 shown in Figure 6 In

[0048] As shown in Figure 6 , the cutting portion 20 in the insert 1 of the present example has a first cutting edge Fl and a second cutting edge F2 as the front cutting edge F. The first cutting edge Fl is formed at a position of an end portion of the front cutting edge F that includes a front end side in a direction in which the cutting portion 20 protrudes from the base portion 10. The second cutting edge F2 is located between the first cutting edge Fl and the side cutting edge S.

[0049] The first cutting edge Fl and the second cutting edge F2 are both curved, and a radius of curvature Rl of the first cutting edge Fl is larger than a radius of curvature R2 of the second cutting edge F2.

[0050] By being configured as described above, it is possible to easily avoid the thickness of the chip becoming too thin. Therefore, it is possible to make it less likely that the machined surface of the workpiece will be crushed. As a result, it is possible to further reduce the surface roughness of the machined surface. Hereinafter, the reason for this will be described with reference to Figure 7

[0051] Figure 7 is a schematic view showing the shape of a chip generated at the front cutting edge F at the time of cutting. In Figure 7 , the chip 301 is indicated by hatching. Note that Figure 7 the drawing indicated by reference numeral 7001 and reference numeral 7002 shows the shape of a chip when the insert of the reference example is used. In addition,​​Figure 7 The figure shown by reference numeral 7003 illustrates the shape of the chips when using the blade 1 according to an embodiment of the present invention. Figure 7 The diagram shows the use of the front cutting edge F on the workpiece 201 (see reference). Figures 13-16 In the case of cutting the surface of the blade, as shown in the figures 7001-7003, the feed rate and depth of cut of the blade are set to be the same.

[0052] When the radii of curvature R1 and R2 are the same value and are relatively small, such as Figure 7 As shown by reference numeral 7001 in the attached drawing, the thickness of the chip 301 increases, making it less prone to cracking on the machined surface during cutting. However, since the radii of curvature R1 and R2 are relatively small, the unevenness caused by the curve shapes of the first cutting edge F1 and the second cutting edge F2 is relatively large, and the surface roughness of the machined surface is prone to increase.

[0053] Furthermore, when the radii of curvature R1 and R2 are the same value and are relatively large, such as Figure 7 As shown by reference numeral 7002 in the attached drawing, the first cutting edge F1 and the second cutting edge F2 have gentle curved shapes, so the unevenness caused by the curved shapes of the first cutting edge F1 and the second cutting edge F2 is small. However, since the thickness of the chip 301 is reduced, it is easy for cracks to occur on the machined surface during cutting.

[0054] On the other hand, when the radius of curvature R1 is greater than the radius of curvature R2, such as Figure 7 As shown by reference numeral 7003 in the accompanying drawings, the surface roughness of the machined surface can be reduced. Specifically, since the radius of curvature R1 is relatively large, the unevenness caused by the curve shapes of the first cutting edge F1 and the second cutting edge F2 is smaller. Furthermore, since the radius of curvature R2 is relatively small, the thickness of the chip 301 is thicker, making it less likely to crack on the machined surface during cutting. As a result, the surface roughness of the machined surface can be reduced.

[0055] The second cutting edge F2 can also be longer than the first cutting edge F1. In other words, the length of the line segment of the second cutting edge F2 from one end to the other can also be greater than the length of the line segment of the first cutting edge F1 from one end to the other.

[0056] By adopting the above structure, the portion where the chip thickness becomes too thin can be reduced. Therefore, the machined surface of the workpiece is less prone to cracking. As a result, the surface roughness of the machined surface can be further reduced.

[0057] Further, the cutting portion 20 in this example has a third cutting edge F3 between the second cutting edge F2 and the cross cutting edge S as the front cutting edge F. Thereby, the strength of the cutting edge near the boundary of the second cutting edge F2 and the cross cutting edge S can be improved compared to the case where the second cutting edge F2 and the cross cutting edge S intersect. Further, the radius of curvature R3 of the third cutting edge F3 can be smaller than the radius of curvature R2 of the second cutting edge F2. Thereby, the strength of the cutting edge can be improved as described above while ensuring the length of the second cutting edge F2 and the cross cutting edge S.

[0058] Further, the cutting portion 20 in this example has a fourth cutting edge F4 extending from the first cutting edge F1 toward the third edge line E3 as the front cutting edge F. The radius of curvature R1 of the first cutting edge F1 can be larger than the radius of curvature R4 of the fourth cutting edge F4. Thereby, the strength of the cutting edge at the portion where the first cutting edge F1 and the third edge line E3 intersect can be improved, and the possibility of the cutting edge being damaged can be reduced. Further, in groove machining, the surface roughness of the groove wall surface can be reduced.

[0059] Further, the radius of curvature R2 of the second cutting edge F2 can be larger than the radius of curvature R4 of the fourth cutting edge F4. Thereby, the front cutting edge F can be enlarged. Thus, the strength of the front cutting edge F is high. Further, in groove machining, the cutting residue between the groove wall surface and the groove bottom surface can be reduced, and the machining accuracy in groove machining can be improved.

[0060] Figure 8 is Figure 6 A-A line sectional view. As Figures 4-6 and Figure 8 shown in FIG. 1, the upper surface 21 has a concave-convex shape rather than a flat shape. Specifically, in this example, the upper surface 21 has a front inclined surface 21a, a cross inclined surface 21b, a flat bottom surface 21c, and a chip breaker protrusion 21d.

[0061] Further, the front inclined surface 21a formed in the upper surface 21 is disposed so as to extend along the front cutting edge F (first edge line E1), and inclines downward as it moves away from the front cutting edge F. The front inclined surface 21a has a first inclined surface 211 disposed along the first cutting edge F1, and a second inclined surface 212 disposed along the second cutting edge F2. Further, the front inclined surface 21a of the cutting portion 20 in this example has a third inclined surface 213 disposed along the third cutting edge F3, and a fourth inclined surface 214 disposed along the fourth cutting edge F4.

[0062] The cross inclined surface 21b extends along the cross cutting edge S (second edge line E2), and has an inclination that descends toward the bottom surface 21c.

[0063] The chip-breaking protrusion 21d extends along the second side surface 24, rising from the bottom surface 21c toward the second side surface 24. The intersection of the second side surface 24 and the surface of the chip-breaking protrusion 21d is the third ridge line E3. The chip-breaking protrusion 21d is a component that guides the direction of travel of chips generated by cutting the workpiece through the front cutting edge F or the cross cutting edge S toward the discharge direction, and also cuts off the chips. By contacting the chip-breaking protrusion 21d, the chips are curled, resulting in good chip discharge.

[0064] exist Figure 8 In the diagram, the lines connecting points A1, A2, and A3 are based on the chip-breaking protrusion 21d, and the lines connecting points A3 and A4 are based on the bottom surface 21c. Additionally, the lines connecting points A4 and A5 are based on the transverse inclined surface 21b. A curved surface can be interposed between the upright surface of the chip-breaking protrusion 21d and the bottom surface 21c, or they can be directly connected. Similarly, a curved surface can be interposed between the bottom surface 21c and the transverse inclined surface 21b, or they can be directly connected.

[0065] (3. Regarding the shape of the forward inclined surface 21a)

[0066] The following uses Figure 9 and Figure 10 The multiple inclined surfaces (first inclined surface 211 to fourth inclined surface 214) corresponding to the multiple cutting edges (first cutting edge F1 to fourth cutting edge F4) formed on the front end portion of the cutting part 20 will be described. Figure 9 Is to make Figure 6 The diagram shows an enlarged view of the front end portion of the cutting section 20 rotated 90° clockwise. Figure 10 yes Figure 9 BB-FF sectional view.

[0067] like Figure 9 As shown, the explanation is based on the cross sections (BB section to FF section) of five parts when the front end portion of the cutting part 20 is cut by a plane that is parallel to the height direction of the cutting part 20 and orthogonal to the front end (first ridge line E1) of the cutting part 20.

[0068] like Figure 10 As shown by reference numeral 9001 in the accompanying drawings, when viewed in cross-section including the first inclined surface 211, the angle formed by the first inclined surface 211 relative to the front end surface 22 is defined as the first inclined angle θ1.

[0069] In addition, such as Figure 10The second inclination angle of the second inclined surface 212 (the second inclination angle θ21 or the second inclination angle θ22) of the cutting portion 20 in this example can also be greater than the first inclination angle θ1 of the first inclined surface 211. In other words, the first inclination angle θ1 can also be smaller than the second inclination angle. Figure 10 The second inclination angle of the second inclined surface 212 (the second inclination angle θ21 or the second inclination angle θ22) of the cutting portion 20 in this example can also be greater than the first inclination angle θ1 of the first inclined surface 211. In other words, the first inclination angle θ1 can also be smaller than the second inclination angle. Figure 10 The second inclination angle of the second inclined surface 212 (the second inclination angle θ21 or the second inclination angle θ22) of the cutting portion 20 in this example can also be greater than the first inclination angle θ1 of the first inclined surface 211. In other words, the first inclination angle θ1 can also be smaller than the second inclination angle.

[0070] The second inclination angle of the second inclined surface 212 (the second inclination angle θ21 or the second inclination angle θ22) of the cutting portion 20 in this example can also be greater than the first inclination angle θ1 of the first inclined surface 211. In other words, the first inclination angle θ1 can also be smaller than the second inclination angle. Figure 10 The second inclination angle of the second inclined surface 212 (the second inclination angle θ21 or the second inclination angle θ22) of the cutting portion 20 in this example can also be greater than the first inclination angle θ1 of the first inclined surface 211. In other words, the first inclination angle θ1 can also be smaller than the second inclination angle. Figure 11 The second inclination angle of the second inclined surface 212 (the second inclination angle θ21 or the second inclination angle θ22) of the cutting portion 20 in this example can also be greater than the first inclination angle θ1 of the first inclined surface 211. In other words, the first inclination angle θ1 can also be smaller than the second inclination angle.

[0071] The second inclination angle of the second inclined surface 212 (the second inclination angle θ21 or the second inclination angle θ22) of the cutting portion 20 in this example can also be greater than the first inclination angle θ1 of the first inclined surface 211. In other words, the first inclination angle θ1 can also be smaller than the second inclination angle.

[0072] Since the first cutting edge F1 includes the end portion of the front end side of the front cutting edge F, a greater cutting load is easily applied to the first cutting edge F1, for example, during groove machining and the like. In the case where the first inclination angle θ1 is relatively small, the wall thickness of the blade 1 in the vicinity of the first cutting edge F1 is easily ensured. That is, chipping is less likely to occur in the vicinity of the first cutting edge F1. Thus, stable cutting machining can be performed even during groove machining and the like, and the versatility of the blade 1 is high.

[0073] Furthermore, in the case where the upper surface 21 has the chip breaker protrusion 21d extending along the second side surface 24 and protruding toward the second side surface 24 from the bottom surface 21c, the second inclination angle is relatively large, and thus the chip generated by the second cutting edge F2 easily advances toward the chip breaker protrusion 21d. Thus, the handling property of the chip is improved.

[0074] Further, the first inclined surface 211 can also have a region in which the inclination angle becomes larger as it approaches the second inclined surface 212. Thus, the first cutting edge Fl can have a portion in which the sharpness becomes good as it approaches the second cutting edge F2. Therefore, while the durability of the first cutting edge Fl is ensured at the time of ensuring the groove processing and the like, the possibility of the occurrence of a burr on the machined surface in the reverse cross-cut processing and the like becomes small.

[0075] Further, the second inclined surface 212 can also have a region (front side second inclined surface 212a) in which the inclination angle becomes smaller as it approaches the first inclined surface 211. Since the first cutting edge Fl includes the end portion of the front end side of the front cutting edge F, the second cutting edge F2 approaches the end portion of the front end side of the front cutting edge F as it approaches the first cutting edge Fl. At this time, in the case where the second inclined surface 212 has the above-mentioned region, it is easy to ensure that the wall thickness of the insert 1 at the portion where the second inclined surface 212 is disposed becomes thicker as it approaches the first inclined surface. Therefore, chipping is less likely to occur in the second cutting edge F2. In the case where the above-mentioned region is connected to the first inclined surface 211, chipping is even less likely to occur in the second cutting edge F2.

[0076] The second inclined surface 212 can also have a region (lateral side second inclined surface 212b) in which the inclination angle becomes larger as it approaches the third inclined surface 213. That is, the second inclination angle Θ22 of the lateral side second inclined surface 212b can also be larger than the second inclination angle Θ21 of the front side second inclined surface 212a. The radius of curvature R3 of the third cutting edge F3 is smaller than the radius of curvature R2 of the second cutting edge F2. In this case, it is difficult to ensure the area of the third inclined surface 213 with respect to the length of the third cutting edge F3 being large, and thus the chips generated by the third cutting edge F3 can possibly clog in the third inclined surface 213.

[0077] However, in the case where the second inclined surface 212 has the above-mentioned region (lateral side second inclined surface 212b), since the second inclination angle Θ22 is relatively large, the chips easily flow in the lateral side second inclined surface 212b. Therefore, the chips generated by the third cutting edge F3 easily flow into the lateral side second inclined surface 212b. As a result, clogging of the chips in the third inclined surface 213 is less likely to occur. Note that, in the case where the above-mentioned region (lateral side second inclined surface 212b) is connected to the third inclined surface 213, clogging of the chips in the third inclined surface 213 is even less likely to occur.

[0078] (4. Material of the insert, etc.)

[0079] As the material of the insert 1, for example, inorganic materials such as superhard alloy, cermet, and ceramic can be mentioned. As the composition of the superhard alloy, for example, WC (tungsten carbide)-Co, WC-TiC (titanium carbide)-Co, and WC-TiC-TaC (tantalum carbide)-Co can be mentioned.

[0080] Here, WC, TiC, and TaC are hard particles, and Co is a binding phase. In addition, the cermet is a sintered composite material in which a metal is compounded in a ceramic component. Specifically, as the cermet, a compound in which TiC or TiN (titanium nitride) is a main component can be cited. Of course, the material of the blade 1 is not limited to these.

[0081] In addition, although not particularly illustrated, the blade 1 can also have a structure in which a main body containing the above-described material and a cover layer covering the main body are provided. As the material of the cover layer, for example, titanium carbide, titanium nitride, titanium oxide, titanium oxycarbide, titanium oxynitride, titanium carbonitride, and titanium carbonoxynitride, and the like can be cited. The cover layer can contain only one of the above-described materials, or can contain a plurality of them. In addition, the cover layer can be composed of one layer, or can have a structure in which a plurality of layers are laminated. Note that the material of the cover layer is not limited to these.

[0082] The cover layer can be located on the base body by using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method. For example, in a case where the cover layer is formed by the above-described vapor deposition method in a state where the base body is held by the inner peripheral surface of the through hole 13, the cover layer can be disposed in a manner of covering the entire surface of the base body except for the inner peripheral surface of the through hole 13.

[0083] (5. Cutting tool)

[0084] Next, the cutting tool 101 of the embodiment will be described using Figure 12 , Figure 11 the drawings. Figure 12 is a perspective view illustrating the cutting tool 101 of the embodiment. Figure 11 is an enlarged view of the region B4 illustrated in Figure 11 .

[0085] As illustrated in Figure 12 , the cutting tool 101 of the embodiment is a tool in which a blade 1 is provided to a rod-shaped body on the front end side. The cutting tool 101 has a tool shank 105 in which a blade pocket 103 is provided on the front end side, and the above-described blade 1 located in the blade pocket 103.

[0086] As illustrated in Figures 13-16 , the blade pocket 103 is a portion in which the blade 1 is fitted, and has a seating surface and a constraint side surface inclined with respect to the seating surface. In addition, the blade pocket 103 is open on the front end side of the tool shank 105.

[0087] The insert 1 is assembled so that at least a portion of the cutting edge used in the cutting portion 20, i.e., the aforementioned front cutting edge F and at least a portion of the side cutting edge S, protrudes outward from the shank 105. In this example, when the insert 1 is mounted to the shank 105, the upper side surface 14 of the base portion 10 becomes the upper end of the insert 1, and the lower side surface 15 of the base portion 10 becomes the lower end of the insert 1. In this example, the insert 1 is assembled to the shank 105 by the screw 107.

[0088] In addition, in a state where the insert 1 is assembled to the pocket 103, the base portion 10 of the insert 1 can be in direct contact with the pocket 103, or a sheet or the like can be interposed between the insert 1 and the pocket 103.

[0089] As the material of the shank 105, steel, cast iron, or the like is used. In particular, in the case where steel is used among these materials, the toughness of the shank 105 can be improved.

[0090] Such a cutting tool 101 is used for so-called turning processing, and can be used in plunge reverse horizontal processing. However, the cutting tool 101 can be used for internal diameter processing, external diameter processing, and grooving processing, for example, but is not limited to plunge reverse horizontal processing.

[0091] (6. Method for manufacturing cutting processed product)

[0092] Next, a method for manufacturing a cutting processed product according to the embodiment will be described. Figures 13-16 A method for manufacturing a cutting processed product according to the embodiment will be described. Figures 13-16 is a schematic view showing one step of a method for manufacturing a cutting processed product according to the embodiment. Figure 13 is a state where the cutting tool 101 to which the insert 1 is assembled is viewed from the upper surface 21 side of the cutting portion 20.

[0093] A cutting processed product is produced by cutting processing a workpiece 201. A method for manufacturing a cutting processed product according to the embodiment includes the following steps. That is,

[0094] (1) a step of rotating the workpiece 201;

[0095] (2) a step of bringing the cutting tool 101 into contact with the rotating workpiece 201; and

[0096] (3) a step of separating the cutting tool 101 from the workpiece 201.

[0097] More specifically, first, as shown in Figure 14 the workpiece 201 is rotated around the axis O1, and the cutting tool 101 is relatively approached to the workpiece 201. Next, as shown in Figure 15As shown, the front cutting edge F and the side cutting edge S in the cutting tool 101, which are cutting edges, are brought into contact with the workpiece 201, and the workpiece 201 is cut. Also, as shown in Figure 16 As shown, the cutting edges in the cutting tool 101 are brought into contact with the workpiece 201 in a state in which the cutting tool 101 is relatively moved in the axial direction of the axis O1 with respect to the rotating workpiece 201, and the workpiece 201 is cut. At this time, the side cutting edge S is directed toward the front of the moving direction. Then, as shown in Figure 13 As shown, the cutting tool 101 is relatively moved away from the workpiece 201.

[0098] In the example of Figure 14 and Figure 14 , the cutting tool 101 is moved in a state in which the axis O1 is fixed and the workpiece 201 is rotated around the axis O1, and thereby the workpiece 201 is approached. Also, in the example of Figure 15 and Figure 16 , the workpiece 201 is cut by bringing the cutting edges in the blade 1 into contact with the rotating workpiece 201. Also, in ​ , the cutting tool 101 is moved away by moving the cutting tool 101 in a state in which the workpiece 201 is rotated.

[0099] Note that, in the cutting process in the manufacturing method of the embodiment, in each process, the cutting tool 101 is brought into contact with the workpiece 201 or is moved away from the workpiece 201 by moving the cutting tool 101. However, of course, it is not limited to this manner.

[0100] For example, in the process of (1), the workpiece 201 can be moved toward the cutting tool 101. In the process of (3), the workpiece 201 can be moved away from the cutting tool 101. In the case of continuing the cutting process, a state in which the workpiece 201 is rotated is maintained, and the process of bringing the cutting edges in the blade 1 into contact with different portions of the workpiece 201 is repeated.

[0101] Note that, as a representative example of the material of the workpiece 201, carbon steel, alloy steel, stainless steel, cast iron, or a non-ferrous metal, and the like can be given.

[0102] As described above, the cutting insert of one aspect of the present application has a base portion and a cutting portion provided in a manner projecting from the base portion, the cutting portion having a front end surface located on a front end side in a direction of projection from the base portion, an upper surface extending from the base portion to the front end surface, a first side surface extending from the base portion to the front end surface and adjacent to the upper surface, a second side surface extending from the base portion to the front end surface and adjacent to the upper surface on an opposite side of the first side surface, a front cutting edge located at a position where the upper surface and the front end surface intersect, and a transverse cutting edge located at a position where the upper surface and the first side surface intersect. The front cutting edge has a first cutting edge including an end portion of the front end side in the front cutting edge, and a second cutting edge located between the first cutting edge and the transverse cutting edge, the first cutting edge having a radius of curvature greater than a radius of curvature of the second cutting edge.

[0103] Sometimes, high-precision cutting machining is required to further reduce the surface roughness of a machined surface. An object of one aspect of the present application is to provide a cutting insert capable of further reducing the surface roughness of a machined surface.

[0104] According to one aspect of the present application, it is possible to easily avoid the thickness of a chip becoming too thin. Therefore, it is difficult for a machined surface of a workpiece to be crushed. As a result, it is possible to further reduce the surface roughness of a machined surface.

[0105] 〔Additional Matters〕

[0106] The above describes the present application of the present disclosure based on the drawings and examples. However, the present application of the present disclosure is not limited to the above-described embodiments. That is, the present application of the present disclosure can be variously changed within the scope of the present application, and embodiments obtained by appropriately combining the technical means disclosed in the respective embodiments are also included in the technical scope of the present application of the present disclosure. That is, it should be noted that various modifications or corrections can be easily made by those skilled in the art based on the present application. In addition, it should be noted that these modifications or corrections are included in the scope of the present disclosure.

[0107] Explanation of Reference Signs:

[0108] 1 Insert (cutting insert)

[0109] 10 Base portion

[0110] 11 First main surface

[0111] 12 Second main surface

[0112] 13 Through-hole

[0113] 14 Upper side surface

[0114] 15 lower side surface

[0115] 16 stepped surface

[0116] 20 cutting portion

[0117] 21 upper surface

[0118] 21a front inclined surface

[0119] 21b lateral inclined surface

[0120] 21c bottom surface

[0121] 21d chip breaker

[0122] 22 front end surface

[0123] 23 first side surface

[0124] 24 second side surface

[0125] 25 lower surface

[0126] 101 cutting tool

[0127] 103 pocket

[0128] 105 shank

[0129] 107 screw

[0130] 201 workpiece

[0131] 211 first inclined surface

[0132] 212 second inclined surface

[0133] 212a front-side second inclined surface

[0134] 212b lateral-side second inclined surface

[0135] 213 third inclined surface

[0136] 214 fourth inclined surface

[0137] E1 first edge line

[0138] E2 second edge line

[0139] E3 third edge line

Claims

1. A cutting insert comprising a base portion and a cutting portion disposed in a manner protruding from said base portion. The cutting part has: The front end face is located on the front end side in the direction of protrusion from the base portion; The upper surface extends from the base portion to the front end face; The first side surface extends from the base portion to the front end surface and is adjacent to the upper surface; The second side extends from the base portion to the front end face and is adjacent to the upper surface on the opposite side of the first side. The front cutting edge is located at the intersection of the upper surface and the front end face; and The cross-cutting edge is located at the intersection of the upper surface and the first side surface. Its features are, The front cutting edge has: A first cutting edge, comprising an end portion of the front cutting edge on the front end side; and The second cutting edge is located between the first cutting edge and the transverse cutting edge. The radius of curvature of the first cutting edge is greater than that of the second cutting edge. The upper surface has a forward inclined surface that is positioned along the front cutting edge and slopes downwards as it moves away from the front cutting edge. The forward inclined surface has: A first inclined surface is arranged along the first cutting edge; as well as A second inclined surface, which is configured along the second cutting edge. The second tilt angle of the second tilted surface is greater than the first tilt angle of the first tilted surface.

2. The cutting blade according to claim 1, characterized in that, The second inclined surface has a region where the inclination angle decreases as it approaches the first inclined surface.

3. The cutting blade according to claim 1, characterized in that, The front cutting edge also has a third cutting edge located between the second cutting edge and the transverse cutting edge. The radius of curvature of the third cutting edge is smaller than that of the second cutting edge.

4. The cutting insert according to claim 3, characterized in that, The forward inclined surface also has a third inclined surface arranged along the third cutting edge. The second inclined surface has a region where the inclination angle increases as it approaches the third inclined surface.

5. The cutting blade according to claim 1, characterized in that, The front cutting edge also has a fourth cutting edge extending from the first cutting edge toward the second side. The radius of curvature of the first cutting edge is greater than that of the fourth cutting edge.

6. The cutting blade according to claim 5, characterized in that, The radius of curvature of the second cutting edge is greater than that of the fourth cutting edge.

7. The cutting blade according to claim 1, characterized in that, The second cutting edge is longer than the first cutting edge.

8. A cutting tool, characterized in that, The cutting tool has: A knife handle having a cutting groove located on the front end side; and The cutting insert according to any one of claims 1 to 7, wherein it is located within the cutting groove.

9. A method for manufacturing a workpiece by cutting, characterized in that, The method for manufacturing the workpiece includes the following steps: Rotate the workpiece; The cutting tool of claim 8 is brought into contact with the rotating workpiece; and This separates the cutting tool from the workpiece.

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