Method for manufacturing cutting insert, cutting tool, and machined product

Abstract

This insert has an upper surface, a lower surface, side surfaces, a cutting edge, and a through hole. The upper surface includes a first corner of a convex curved shape as well as a first side and second side that extend from the first corner. A first region of the first side surface has a recessed shape depressed toward an axis. The upper surface also has a recess that is located between the second side and the axis and is depressed toward the axis. In the direction running along the axis, the entirety of the recess is located further away from the first corner than the entirety of the first region.

Description

[Technical field]

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

[0002] For example, the cutting tools described in Patent Documents 1 to 3 are known as cutting tools used for cutting workpieces such as metals. The cutting tools described in Patent Documents 1 and 2 have a tip portion protruding toward the workpiece that is thinner than the other portions. In the cutting tool described in Patent Document 3, the cutting insert is fixed to the holder by using a plurality of screws. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2000-190107 [Patent Document 2] Japanese Patent Publication No. 2005-040942 [Patent Document 3] Japanese Patent Publication No. 2006-035390 Summary of the Invention

[0004] A non-limiting example of a cutting insert in the present disclosure has an upper surface, a lower surface, a side surface, a cutting edge, and a through hole. The upper surface has a first corner having a convex curved shape, and a first side and a second side extending from the first corner. The lower surface is located opposite the upper surface. The side surface is located between the upper surface and the lower surface. The cutting edge is located at the first corner and the first side. The through hole opens at the upper surface and the lower surface. The side surface has a first side surface extending from the first side to the lower surface, and a second side surface extending from the second side to the lower surface. When the upper surface is viewed from the front, The upper surface has a shape that is point-symmetric with respect to a center point of the through hole,A virtual straight line that passes through the tip of the first corner and extends in the major axis direction of the upper surface is referred to as an axis line. The first side surface has a first region and a second region. The first region extends from the first side to the lower surface and ,before The second region is flat and has a concave shape recessed toward the axis line and is located farther from the first corner than the first region. The first side has a first section and a second section, the first section being concave and located along the first region, and the second section being linear and located along the second region. The upper surface has a recess and breaker wall When the upper surface is viewed from the front, the recess is ,before It is concave toward the axis. The breaker wall surface is located between the first section and the axis, and moves away from the lower surface as it moves away from the first section. The recess has a first recess and a second recess. The first recess is located between the second side and the axis, and has a tip portion. The second recess is located point-symmetrically with respect to the first recess, with the center point of the through hole as a reference. The tip portion is closest to the first corner in a direction along the axis. The breaker wall surface has a rear end portion. The rear end portion is farthest from the first corner in a direction along the axis. In a direction along the axis, No. 1 The entire recess is located farther from the first corner than the entire first region. and the rear end is located farther from the first corner than the front end. . [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view of a cutting tool in accordance with a non-limiting embodiment of the present disclosure. [Diagram 2] FIG. 2 is an enlarged view of an area A1 shown in FIG. [Diagram 3] 2 is a perspective view of the cutting tool shown in FIG. 1, seen from a different angle. [Figure 4] FIG. 4 is an enlarged view of an area A2 shown in FIG. [Diagram 5] 2 is a front view of the upper surface of the cutting tool shown in FIG. 1. [Figure 6] FIG. 6 is an enlarged view of an area A3 shown in FIG. 5. [Figure 7] FIG. 2 is a perspective view of a holder in the cutting tool shown in FIG. [Figure 8] FIG. 2 is a perspective view of a non-limiting example insert. [Figure 9] FIG. 9 is an enlarged view of an area A4 shown in FIG. [Figure 10] FIG. 9 is a perspective view of the insert shown in FIG. 8, seen from a different angle. [Figure 11] FIG. 11 is an enlarged view of an area A5 shown in FIG. [Figure 12] FIG. 9 is a front view of the top surface of the insert shown in FIG. 8. [Figure 13] FIG. 13 is an enlarged view of an area A6 shown in FIG. [Figure 14] FIG. 13 is a front view of the insert shown in FIG. 12 as viewed from a direction B1. [Figure 15] 15 is an enlarged view of an area A7 shown in FIG. 14. [Figure 16] 13 is a side view of the insert shown in FIG. 12 as viewed from a direction B2. [Figure 17] FIG. 17 is an enlarged view of an area A8 shown in FIG. [Figure 18] FIG. 14 is an enlarged view of a cross section XVIII-XVIII of the insert shown in FIG. [Figure 19] FIG. 13 is an enlarged view of a cross section XIX-XIX of the insert shown in FIG. [Figure 20] FIG. 2 is a schematic diagram showing a step of a method for manufacturing a machined product in one non-limiting example. [Figure 21] FIG. 2 is a schematic diagram showing a step of a method for manufacturing a machined product in one non-limiting example. [Figure 22] FIG. 2 is a schematic diagram showing a step of a method for manufacturing a machined product in one non-limiting example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Hereinafter, a cutting insert (hereinafter also simply referred to as an insert), a cutting tool, and a method for manufacturing a machined product according to non-limiting embodiments of the present disclosure will be described in detail with reference to the drawings. However, for the sake of convenience, each of the drawings referred to below shows only the main members necessary for explaining the embodiments in a simplified manner. Therefore, the insert and the cutting tool may include any component member not shown in each of the drawings referred to in this specification. In addition, the dimensions of the components in each of the drawings do not faithfully represent the dimensions of the actual components and the dimensional ratios of each component.

[0007] (1. Overview of cutting tools) First, in order to facilitate understanding of the insert of a non-limiting embodiment of the present disclosure, an example of a cutting tool to which the insert is attached will be generally described below with reference to Figs. 1 to 7. Fig. 1 is a perspective view showing a non-limiting example of a cutting tool 1. Fig. 2 is an enlarged view of an area A1 shown in Fig. 1. Fig. 3 is a perspective view of the cutting tool 1 shown in Fig. 1 from another angle. Fig. 4 is an enlarged view of an area A2 shown in Fig. 3. Fig. 5 is a front view of an upper surface 51 of the insert 5 in the cutting tool 1 shown in Fig. 1. Fig. 6 is an enlarged view of an area A3 shown in Fig. 5. Fig. 7 is a perspective view of a holder 3 in the cutting tool 1 shown in Fig. 1.

[0008] The cutting tool 1 illustrated in Fig. 1 to Fig. 6 includes a holder 3, an insert 5, a first screw 7, and a second screw 9. The cutting tool 1 is, for example, a turning tool. Specific examples of the cutting tool 1 include a tool for external diameter machining, a tool for internal diameter machining, a tool for grooving, and a tool for cut-off machining.

[0009] (holder) As shown in Figs. 1 to 7, the holder 3 is, for example, rod-shaped extending along a central axis from a first end 3A to a second end 3B. Hereinafter, the central axis of the holder 3 is referred to as a first central axis O1. In general, the first end 3A is called a front end, and the second end 3B is called a rear end. The part of the holder 3 on the side of the second end 3B (the part shown in a rectangular prism shape in Fig. 1) is also called a shank that can be gripped by a machine tool. The first central axis O1 can be specified by, for example, defining a virtual straight line that passes through the center of the end face of the holder 3 on the side of the second end 3B and is parallel to each side surface of the shank. The holder 3 also has a pocket 11, a first screw hole 13, and a second screw hole 15.

[0010] The pocket 11 is a portion where the insert 5 is attached, and may be located on the side of the first end 3A of the holder 3. In one example, the pocket 11 may be located so as to include the first end 3A, and may be open at the first end 3A. The pocket 11 may have a seating surface 17 and a constraining side surface 19 as surfaces against which the insert 5 abuts. The constraining side surface 19 may be a surface perpendicular to the seating surface 17, or may be an inclined surface. The seating surface 17 may extend parallel to the first central axis O1. Furthermore, the constraining side surface 19 may be inclined with respect to the first central axis O1.

[0011] The constraining side surface 19 may include a first constraining side surface 19A closer to the first central axis O1 and a second constraining side surface 19B farther from the first central axis O1. The pocket 11 may have an accommodation space 11A on the second end 3B side for accommodating the tip portion of the insert 5.

[0012] The first screw hole 13 and the second screw hole 15 are surfaces to which screws for fixing the insert 5 to the holder 3 are attached. Examples of screws for fixing the insert 5 to the holder 3 include a first screw 7 and a second screw 9.

[0013] The first screw hole 13 may open in the pocket 11. For example, the first screw hole 13 may open in the seat surface 17 as shown in FIG. 7. The second screw hole 15 may be located closer to the second end 3B than the first screw hole 13. The second screw hole 15 may open in the pocket 11 like the first screw hole 13, or may be located away from the pocket 11. The second screw hole 15 in the example shown in FIG. 7 may open in the pocket 11, or may be located connected to the first constraining side surface 19A.

[0014] Materials constituting the holder 3 may be, for example, steel, cast iron, or aluminum alloy. The size of the holder 3 may be set appropriately according to the size of the workpiece. The length of the holder 3 in the direction along the first central axis O1 may be set to, for example, about 50 mm or more and 200 mm or less. The width in the direction perpendicular to the first central axis O1 may be set to, for example, about 5 mm or more and 30 mm or less.

[0015] Although details will be described later, the insert 5 has a recess 64, and when the second screw 9 is inserted into the second screw hole 15, a second screw head 9A of the second screw 9 abuts against the recess 64. In the cutting tool 1, the insert 5 is fixed to the holder 3 using both the first screw 7 and the second screw 9, as shown in Figures 1 to 6.

[0016] (Key points of inserts) In recent years, there has been a demand for cutting tools that enable more complex (fine) cutting of workpieces. In addition, cutting tools are also required to be capable of processing with high cutting loads in order to improve the efficiency of cutting. In addition to the above demands, there is also the issue that the accuracy of cutting decreases if the insert vibrates during cutting.

[0017] It is difficult to meet the above-mentioned multiple demands by simply changing the shape of the insert. This is due to the following reasons, for example: (i) In an insert having a tapered tip formed by increasing the length in the longitudinal direction, a large load is generated on the first screw hole 13 and the first screw 7 during cutting.

[0018] (ii) Furthermore, if the overall shape of the insert is made thinner, the diameter of the first screw 7 must be reduced, in which case the binding force of the first screw 7 will decrease and the strength of the insert itself may also decrease. (iii) Usually, the insert has a shape that has some play (clearance) with respect to the pocket 11 of the holder, and in order to ensure the accuracy of the cutting process, the insert needs to be firmly bound when attached to the pocket 11.

[0019] Therefore, the insert 5 in a non-limiting embodiment of the present disclosure is generally shaped to have a tapered tip while maintaining a sufficient thickness in the central portion, and has a recess 64 with which the second screw 9 abuts. The tip and recess 64 of the insert 5 do not overlap with each other in the longitudinal direction.

[0020] According to one aspect of the present disclosure, a cutting insert capable of complex cutting processing while ensuring durability can be realized.

[0021] (2. Insert Details) The insert 5 in one embodiment will be described in detail below with reference to the drawings. FIG. 8 is a perspective view showing an example of the insert 5, which is not limited to the above. FIG. 9 is an enlarged view of an area A4 shown in FIG. 8. FIG. 10 is a perspective view of the insert 5 shown in FIG. 8 from another angle. FIG. 11 is an enlarged view of an area A5 shown in FIG. 10. FIG. 12 is a plan view showing the upper surface 51 of the insert 5 shown in FIG. 8 as viewed from the front (top). FIG. 13 is an enlarged view of an area A6 shown in FIG. 12.

[0022] Fig. 14 is a front view of the insert 5 shown in Fig. 12, seen from the B1 direction. Fig. 15 is an enlarged view of an area A7 shown in Fig. 14. Fig. 16 is a side view of the insert 5 shown in Fig. 12, seen from the B2 direction. Fig. 17 is an enlarged view of an area A8 shown in Fig. 16. Fig. 18 is an enlarged view of a cross section taken along the line XVIII-XVIII of the insert 5 shown in Fig. 13. Fig. 19 is an enlarged view of a cross section taken along the line XIX-XIX of the insert 5 shown in Fig. 12.

[0023] 8 to 19, the insert 5 has an upper surface 51, a lower surface 52 located opposite the upper surface 51, a side surface 53 located between the upper surface 51 and the lower surface 52, a cutting edge 54, and a through hole 55 opening in the upper surface 51 and the lower surface 52. The insert 5 is not limited to a particular shape, but as an example, as shown in FIG. 12, when the insert 5 is viewed from above, the insert 5 may have a shape that is partially recessed in a substantially rectangular shape (substantially diamond shape) so that two tip ends in the longitudinal direction are thinner than the other parts.

[0024] As a non-limiting example, the insert 5 may have an upper surface 51 that is point-symmetric with respect to the center point Q of the through hole 55 when viewed from above, and may be a so-called two-cornered insert.

[0025] 12, etc., upper surface 51 may have four corners and four sides. Of the four corners, one of two corners in the longitudinal direction is defined as a first corner 56, and the other is defined as a second corner 59.

[0026] The upper surface 51 may have a first corner 56 having a convex curved shape, a first side 57 extending from the first corner 56, and a second side 58 extending from the first corner 56. The first side 57 is a side on the side in contact with the first corner 56 on which at least a portion of the cutting edge 54 that can function as a main blade is located. The second side 58 is a side on the opposite side to the first side 57 among the sides in contact with the first corner 56. The cutting edge 54 may not be located on the second side 58. The upper surface 51 may have a second corner 59 having the same or substantially the same shape as the first corner 56 on the opposite side across the through hole 55, and may have a third side 60 extending from the second corner 59 and a fourth side 61 extending from the second corner 59. The cutting edge 54 on the second corner 59 side is located on the third side 60.

[0027] Here, the part of upper surface 51 located at the end farthest in the long axis direction is defined as the tip. When upper surface 51 is viewed from the front (top), an imaginary straight line passing through the tip of first corner 56 and extending in the long axis direction of upper surface 51 is referred to as axis L1. Since upper surface 51 of insert 5 has a shape that is rotationally symmetrical by 180°, axis L1 may be an imaginary straight line passing through the tip of first corner 56 and the tip of second corner 59 when viewed from above. When through hole 55 is provided in the center of upper surface 51, axis L1 may pass through center point Q of through hole 55.

[0028] The axis L1 may be a line that bisects or approximately bisects an angle at an intersection formed by virtually extending the linear first side 57 and second side 58 near the center of the insert 5. Since the upper surface 51 of the insert 5 has a shape that is rotationally symmetrical by 180°, the above-mentioned relationship is also the same for the relationship between the axis L1 and the third side 60 and the fourth side 61 on the second angle 59 side.

[0029] The lower surface 52 is a surface located opposite to the upper surface 51, and may abut against the seat surface 17 when the insert 5 is attached to the holder 3. The lower surface 52 may have the same shape as the upper surface 51, or may have a different shape from the upper surface 51. In one example of the insert 5, the lower surface 52 has a polygonal shape like the upper surface 51.

[0030] The side surface 53 has a first side surface 531 extending from the first edge 57 to the lower surface 52, a second side surface 532 extending from the second edge 58 to the lower surface 52, a third side surface 533 extending from the third edge 60 to the lower surface 52, and a fourth side surface 534 extending from the fourth edge 61 to the lower surface 52.

[0031] The first side surface 531 may have a first region 62 having a concave shape recessed toward the axis L1, and a flat second region 63 located farther from the first corner 56 than the first region 62. The second side surface 532 may be a flat surface overall (see FIG. 10, etc.). The third side surface 533 may have the same or approximately the same shape as the first side surface 531, that is, may have an area corresponding to the first region 62 and the second region 63. The fourth side surface 534 may have the same or approximately the same shape as the second side surface 532.

[0032] In this specification, the term "flat" or "plane" is intended to mean a surface that is not curved at a visibly noticeable level or does not have a visibly noticeable unevenness, and does not require a surface to be strictly flat. Therefore, a surface described as "flat" or "plane" may be allowed to have an unavoidable degree of unevenness in the manufacture of the insert 5. Specifically, the surface may have unevenness with a surface roughness of, for example, about 50 μm.

[0033] In addition, in this specification, the term "straight line shape" with respect to an edge is intended to mean a substantially straight line shape, and does not require the edge to be strictly straight (a straight line with a curvature of 0). Therefore, an edge described as a "straight line shape" may be substantially straight, may have a shape with an unavoidable degree of undulation in the manufacture of the insert 5, and may have irregularities or the like to the extent that the function of the insert 5 in one example of the present disclosure is not impaired. Specifically, in the case of a curve with a radius of curvature that is much larger than the first to third radii of curvature described below, for example, an extremely gentle curve with a radius of curvature exceeding 100 mm, may be regarded as a straight line.

[0034] The cutting edge 54 is located at the first corner 56 and the first side 57, and cuts the workpiece 101 by contacting the rotating workpiece 101 (see Figs. 20 to 22), for example. The cutting edge 54 may be located over the entire first corner 56, or may be located over only a portion of the first corner 56. The cutting edge 54 may be located over the entire first side 57, or may be located over only a portion of the first side 57. The portion of the cutting edge 54 located on the first side 57 can function as a main edge in cutting. Therefore, the portion of the cutting edge 54 located on the first side 57 can generally be called a main cutting edge.

[0035] The cutting edge 54 may be located, for example, at a part of the second side 58. The part of the cutting edge 54 located at the second side 58 may also be used, for example, as a sweeping edge or a cutting edge for oblique sinking. Therefore, the part of the cutting edge 54 located at the second side 58 may generally be called an auxiliary cutting edge or a secondary cutting edge. The insert 5 may be configured such that the cutting edges 54 are also provided at the second corner 59, the third side 60, and the fourth side 61.

[0036] The through hole 55 is a portion where a fixing member for fixing the insert 5 to the holder 3 is attached. In the example shown in FIG. 1 etc., a first screw 7 is inserted as the fixing member. The through hole 55 may have a tapered portion near the opening in the upper surface 51. In other words, the through hole 55 may have a portion on the upper surface 51 side where the inner diameter becomes larger as it moves away from the lower surface 52 and approaches the upper surface 51. The insert 5 may be fixed to the holder 3 by abutting this portion with a first screw head 7A (see FIG. 4), which is the head of the first screw 7.

[0037] The through hole 55 may open at the center of the upper surface 51 and the center of the lower surface 52. In this case, the central axis of the insert 5 indicated by a virtual line passing through the center of the upper surface 51 and the center of the lower surface 52 (hereinafter referred to as the central axis O2) may coincide with the central axis of the through hole 55 (see FIG. 10). The central axis O2 may be the axis of rotational symmetry of the insert 5.

[0038] 12, the upper surface 51 may have a recess 64 located between the second side 58 and the axis line L1 and recessed toward the axis line L1 in top view. In addition, the upper surface 51 may have a recess 64 located between the fourth side 61 and the axis line L1 and recessed toward the axis line L1.

[0039] The head of the second screw 9 can come into contact with the recess 64, and the insert 5 is screwed to the holder 3 by the head of the second screw 9 coming into contact with the recess 64. The insert 5 may have a plurality of recesses 64. In the example shown in FIG. 8 etc., the recesses 64 may be located on each of the four sides of the upper surface 51.

[0040] In the cutting tool 1 of the above-mentioned example, the insert 5 is attached and fixed to the holder 3 so as to use the cutting edge 54 on the first corner 56 side, and the second screw 9 abuts against the recess 64 located on the fourth side 61.

[0041] However, the cutting tool 1 is not limited to this example, and the insert 5 may be attached to the holder 3 such that the second screw 9 abuts against the recess 64 located on the third side 60. Either the recess 64 located on the third side 60 or the recess 64 located on the fourth side 61 may be used depending on the usage mode of the cutting tool 1 (the shape of the holder 3, the direction in which the first corner 56 of the insert 5 protrudes from the holder 3, the direction in which chips flow, etc.).

[0042] In addition, when the insert 5 is attached and fixed to the holder 3 so as to use the cutting edge 54 on the second corner 59 side, either the recess 64 located on the first side 57 or the recess 64 located on the second side 58 may be used.

[0043] In this embodiment, a description will be given of the recess 64 located on the first side 57 and the recess 64 located on the second side 58. The recess 64 located on the third side 60 may have a similar configuration to the recess 64 located on the first side 57, and the recess 64 located on the fourth side 61 may have a similar configuration to the recess 64 located on the second side 58.

[0044] In the insert 5, the entire recess 64 is located farther from the first angle 56 than the entire first region 62 in the direction along the axis L1. In the insert 5, the entire recess 64 is located farther from the second angle 59 than the entire first region 62 in the direction along the axis L1.

[0045] The insert 5 has a tapered tip due to the first concave region 62. This facilitates complex cutting. The insert 5 is fixed to the holder 3 by abutting the second screw 9 against the recess 64, and is therefore more firmly fixed than when the insert 5 is fixed to the holder 3 only by the first screw 7 inserted into the through hole 55.

[0046] 1 etc., the lower surface 52 is pressed against the seat surface 17, the third side surface 533 comes into contact with the second constraining side surface 19B, and at least a part of the fourth side surface 534 comes into contact with the first constraining side surface 19A. This makes it possible to more firmly constrain the insert 5, thereby reducing the possibility that the insert 5 will wobble within the pocket 11 during cutting.

[0047] As described above, the entire recess 64 of the insert 5 is located farther from the first corner 56 or the second corner 59 than the entire first region 62. This ensures a sufficient thickness at the tip of the insert 5. As a result, the possibility of the tip of the insert 5 being insufficient in strength is reduced. When using the cutting edge 54 on the first corner 56 side, the insert 5 is fixed to the holder 3 by the second screw 9 using the recess 64 on the second corner 59 side. This means that the second screw 9 does not get in the way when machining the workpiece 101.

[0048] As described above, the insert 5 has a thin tip angle while providing sufficient strength, so that by using a cutting tool 1 incorporating the insert 5, it is possible to achieve both complex cutting processing and high processing efficiency.

[0049] Moreover, the first side 57 may have a concave first section 65 located along the first region 62, and a linear second section 66 located along the second region 63. The upper surface 51 may further have a breaker wall surface 67 located between the first section 65 and the axis L1, and moving away from the lower surface 52 as it moves away from the first section 65.

[0050] The recess 64 may have a leading end 68 that is closest to the first angle 56 in the direction along the axis L1. The breaker wall 67 may have a trailing end 69 that is farthest from the first angle 56 in the direction along the axis L1. The trailing end 69 may be located farther from the first angle 56 than the leading end 68 in the direction along the axis L1.

[0051] Chips generated at the portion of the cutting edge 54 located at the first side 57 tend to advance in a direction perpendicular to the first side 57. That is, chips generated at the first side 57 tend to advance toward the second side 58, and may advance toward the recess 64 located between the second side 58 and the axis L1. If the chips advance to the recess 64 located between the second side 58 and the axis L1, the second screw 9 may be damaged, or the chips may be jammed between the recess 64 and the second screw 9. Specifically, when the insert 5 is attached to the holder 3 in such a manner that the second screw 9 abuts against the recess 64 of the second side 58, the second screw 9 may be damaged. In addition, in a manner in which the second screw 9 does not abut against the recess 64 of the second side 58, the chips may remain in the recess 64. When the chips remain, for example, when the corner to be used is changed, the chips may be sandwiched between the recess 64 and the second screw 9.

[0052] On the other hand, the above configuration reduces the possibility that chips will flow into the recess 64. This is because the direction of chip flow is easily changed by the breaker wall surface 67 when the chips generated at the first side 57 proceed to the recess 64 located between the second side 58 and the axis L1. Since the breaker wall surface 67 prevents the chips from flowing into the recess 64, the above-mentioned risk is reduced.

[0053] 8 and 12, the first side 57 may have a concave first section 65 located along the first region 62, and a straight second section 66 located along the second region 63. As shown in Fig. 13, the first section 65 may have, in a top view, a straight first portion 70 connected to the first corner 56, a convex curved second portion 71 connected to the second section 66, and a concave curved third portion 72 located between the first portion 70 and the second portion 71.

[0054] When the first side 57 has the first portion 70 having a linear shape connected to the first corner 56, the direction in which the chips flow generated by the first portion 70 tends to be stable. Therefore, the flow of the chips as a whole tends to be stable. From the viewpoint of further stabilizing the direction in which the chips flow, the length of the first portion 70 may be longer than the other portions constituting the first section 65.

[0055] Furthermore, when the first side 57 has the third portion 72 having a concave curved shape located between the first portion 70 and the second portion 71, the durability of the cutting edge 54 is high. When the cutting edge 54 has a concave shape, the cutting load tends to concentrate near the bottom of the concave shape. However, when the third portion 72 corresponding to the bottom has a concave curved shape, it is easy to avoid the load from concentrating locally on the bottom of the concave shape. Therefore, the durability of the cutting edge 54 as a whole is high.

[0056] The cutting edge 54 has high durability even when the first side 57 has the second portion 71 in a convex curve shape connected to the second section 66. When the first side 57 has the first section 65 in a concave shape and the second section 66 in a straight line shape, there is a risk of cutting loads concentrating on the boundary between these sections. However, when the second portion 71, which is the portion of the first section 65 connected to the second section 66, has a convex curve shape, the first section 65 and the second section 66 are likely to be smoothly connected. Therefore, cutting loads are unlikely to concentrate on the boundary between the first section 65 and the second section 66, and the cutting edge 54 as a whole has high durability.

[0057] As described above, when the first side 57 has the first portion 70, the second portion 71, and the third portion 72, it is possible to improve both the durability of the cutting edge 54 and the chip removal performance.

[0058] When viewed from above, the radius of curvature of the first corner 56, which is a convex curved shape, is defined as the first radius of curvature, the radius of curvature of the second portion 71, which is a convex curved shape, is defined as the second radius of curvature, and the radius of curvature of the third portion 72, which is a concave curved shape, is defined as the third radius of curvature. The insert 5 may have a first radius of curvature larger than the second radius of curvature and a third radius of curvature larger than the first radius of curvature. The first radius of curvature may be set to, for example, about 0.2 to 0.8 mm. The second radius of curvature may be set to, for example, about 0.1 to 0.4 mm. The third radius of curvature may be set to, for example, about 0.5 to 2 mm.

[0059] A large cutting load is likely to be applied to the first corner 56 and the third portion 72 compared to the second portion 71. Furthermore, when the first to third radii of curvature are all large values, the insert 5 becomes large and is difficult to miniaturize. When the first and third radii of curvature are large compared to the second radius of curvature, the insert 5 can be miniaturized while achieving high durability. Therefore, the insert 5 enables complex cutting while ensuring durability.

[0060] In addition, because the third portion 72 has a concave shape, the chips generated in the third portion 72 are more likely to be torn apart along the chip travel direction as they move away from the third portion 72. If the chips are torn apart, the flow of the chips may become unstable. However, when the third radius of curvature is larger than the first radius of curvature, the curve of the third portion 72 becomes gentler. Therefore, the chips are less likely to be torn apart. Therefore, in addition to the durability of the cutting edge 54 and the degree of freedom in cutting processing, the chip discharge performance can also be improved.

[0061] 12, the first section 65 may further include a linear fourth portion 73 located between the second portion 71 and the third portion 72. When viewed from above, the inclination angle of the first portion 70 with respect to the axis L1 may be smaller than the inclination angle of the second side 58 with respect to the axis L1. When the top surface 51 is viewed from the front, the inclination angle of the fourth portion 73 with respect to the axis L1 may be larger than the inclination angle of the second side 58 with respect to the axis L1. When the top surface 51 is viewed from the front, the inclination angle of the second section 66 with respect to the axis L1 may be the same as the inclination angle of the second side 58 with respect to the axis L1.

[0062] According to the above configuration, for example, compared with a case where the first section 65 does not have the fourth portion 73, it is easy to ensure a large area at the tapered tip portion of the insert 5. Therefore, it becomes easier to perform complex cutting processing, and processing efficiency is improved.

[0063] As described above, from the viewpoint of further stabilizing the direction of chip flow, the length of the first portion 70 may be longer than the other portions constituting the first section 65. Therefore, the first portion 70 may be longer than the fourth portion 73.

[0064] (3. Insert material, etc.) The material of the insert 5 may be, for example, a cemented carbide or a cermet. The composition of the cemented carbide may be, for example, WC-Co, WC-TiC-Co, or WC-TiC-TaC-Co. WC-Co is produced by adding cobalt (Co) powder to tungsten carbide (WC) and sintering the mixture. WC-TiC-Co is produced by adding titanium carbide (TiC) to WC-Co. WC-TiC-TaC-Co is produced by adding tantalum carbide (TaC) to WC-TiC-Co.

[0065] A cermet is a sintered composite material in which a ceramic component is combined with a metal. Specifically, the cermet includes a cermet whose main component is a titanium compound such as titanium carbide (TiC) or titanium nitride (TiN).

[0066] The surfaces of the above members constituting the insert 5 may be coated with a film by using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method. The composition of the film may be titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), or alumina (Al 2 O 3 ) etc.

[0067] The size of the insert 5 is not particularly limited. For example, the length of one side of the polygonal upper surface 51 can be set to about 10 to 25 mm. Moreover, the height from the upper surface 51 to the lower surface 52, in other words, the height in the direction along the second central axis O2, can be set to about 2 to 5 mm.

[0068] The size of the recess 64 is not particularly limited. For example, the width in the direction along the first side 57 or the second side 58 when the top surface 51 is viewed from the front can be set to about 3 to 8 mm. Furthermore, the width in the direction perpendicular to the first side 57 or the second side 58 when the top surface 51 is viewed from the front (the depth of the recess 64) can be set to about 1 to 3 mm. Furthermore, the width in the direction perpendicular to the first side 57 or the second side 58 when the side surface 53 is viewed from the front (the depth of the recess 64) can be set to about 0.5 to 1 mm.

[0069] (1st screw, 2nd screw) The first screw 7 is inserted into the through hole 55 and screwed into the first screw hole 13. The second screw 9 abuts against the recess 64 and screwed into the second screw hole 15. As described above, the first screw 7 and the second screw 9 are each a member for fixing the insert 5 to the holder 3.

[0070] Here, the first screw 7 may function as a main member for fixing the insert 5 to the holder 3. The second screw 9 may function as a member for preventing the insert 5 from rotating with the first screw 7 as a reference.

[0071] Since the recess 64 opens on the side surface 53 and the second screw 9 abuts against this recess 64, the second screw 9 can easily prevent the insert 5 from rotating around the first screw 7. In addition, since the recess 64 also opens on the top surface 51, the second screw 9 can be easily attached and can be easily brought into stably abutment against the recess 64.

[0072] In addition, the recess 64 in the embodiment may be located away from the lower surface 52. That is, compared to a case where the recess 64 reaches the lower surface 52, the amount (spatial volume) of the recess 64 in the insert 5 can be reduced. This prevents a decrease in durability due to the provision of the notch in the insert 5. This allows the strength of the insert 5 to be secured while preventing the insert 5 from rotating.

[0073] The first screw 7 and the second screw 9 may be made of, for example, steel, cast iron, aluminum alloy, or the like.

[0074] Since the through hole 55 opens on the upper surface 51 and the lower surface 52, the first screw 7 may be inclined with respect to the cutting edge 54. For example, the first screw 7 may be generally perpendicular to the cutting edge 54. On the other hand, the principal component force, which is the largest force applied to the cutting edge 54 during cutting, tends to be applied mainly in a direction perpendicular to the cutting edge 54. Therefore, the principal component force, which is the largest force applied to the cutting edge 54 during cutting, is unlikely to be directly transmitted to the first screw 7, and the durability of the first screw 7 is high.

[0075] At this time, the second screw 9 may also be perpendicular to the cutting edge 54. In this case, the principal force is less likely to be directly transmitted to the second screw 9, and the durability of the second screw 9 is high.

[0076] The second screw 9 may be inclined with respect to the first screw 7, or may be parallel to the first screw 7. When the second screw 9 is parallel to the first screw 7, rotation of the insert 5 is more easily prevented. The insert 5 is likely to rotate based on the first screw 7, but since the second screw 9 is perpendicular to the direction of rotation, the rotational movement of the insert 5 can be stably received by the second screw 9.

[0077] The second screw 9 may abut against the recess 64 of the insert 5, but may be spaced from the side surface 53. In this case, the side surface 53, which can be used as a clearance surface, is less likely to be damaged. Also, while the second screw head 9A (see FIG. 4) abuts against the recess 64, the thread groove of the second screw 9 is less likely to come into contact with the insert 5. Therefore, the thread groove of the second screw 9 is less likely to be damaged.

[0078] As described above, the pocket 11 of the holder 3 may have the constraining side surface 19. Also, the side surface 53 of the insert 5 may abut against the constraining side surface 19. At this time, the insert 5 may be positioned between the constraining side surface 19 and the second screw 9. When the insert 5 is positioned between the constraining side surface 19 and the second screw 9 in this manner, the insert 5 is less likely to become misaligned.

[0079] Furthermore, when the constraint side surface 19 is inclined with respect to the first central axis O, the thrust force, which is one of the forces applied to the cutting edge 54 during cutting, is easily received by the constraint side surface 19. Therefore, the load on the first screw 7 and the second screw 9 due to the thrust force is easily reduced. Therefore, the durability of the first screw 7 and the second screw 9 is high. For example, as shown in FIG. 7, when the constraint side surface 19 is inclined so as to move away from the first central axis O toward the first end 3A, the thrust force is easily received by the constraint side surface 19.

[0080] The first screw 7 and the second screw 9 may be different sizes or the same size. When the first screw 7 and the second screw 9 are the same size, for example, there is no problem even if the first screw 7 and the second screw 9 are attached in reverse. This makes it easier to manufacture the cutting tool 1 or to replace the insert 5. In addition, since the first screw 7 and the second screw 9 can be made common, it is also possible to reduce manufacturing costs.

[0081] (4. Insert configuration example) 12, in this embodiment, a configuration in which the first side 57 and the cutting edge 54 are located on the left side when the insert 5 is viewed from above will be described as an example, but the present invention is not limited to this configuration. For example, the insert 5 may be configured such that the first side 57 and the cutting edge 54 are located on the right side when viewed from above. In other words, the insert 5 may have a shape obtained by flipping the shape shown in FIG. 12 etc.

[0082] (5. Manufacturing method of machined products) Next, the manufacturing method of the machined product of the embodiment will be described with reference to the drawings. Fig. 20 is a schematic diagram showing one step of the manufacturing method of the machined product 103 in one non-limiting example. Fig. 21 is a schematic diagram showing one step of the manufacturing method of the machined product 103 in one non-limiting example. Fig. 22 is a schematic diagram showing one step of the manufacturing method of the machined product 103 in one non-limiting example.

[0083] The machined product 103 is produced by cutting the workpiece 101. In the embodiment, an outer diameter machining is exemplified as the cutting. The manufacturing method of the machined product 103 in the embodiment includes the following steps. That is, (1) rotating a workpiece 101; (2) contacting a rotating workpiece 101 with a cutting tool 1 such as the one typified by the above-described embodiment; (3) removing the cutting tool 1 from the workpiece 101; Includes.

[0084] More specifically, first, as shown in Fig. 20, the workpiece 101 is rotated around the axis D in the direction D1. Moreover, the cutting tool 1 is moved in the direction D2 to bring the cutting tool 1 relatively closer to the workpiece 101. Next, as shown in Fig. 21, the cutting edge 54 of the cutting tool 1 is brought into contact with the workpiece 101 to cut the workpiece 101.

[0085] At this time, outer diameter machining can be performed by cutting the workpiece 101 while moving the cutting tool 1 in the D3 direction. Then, as shown in Fig. 22, the cutting tool 1 is moved relatively far away from the workpiece 101 by moving the cutting tool 1 in the D4 direction.

[0086] In Fig. 20, the axis D is fixed and the cutting tool 1 is brought closer while the workpiece 101 is being rotated. In Fig. 21, the cutting edge 54 of the insert 5 is brought into contact with the rotating workpiece 101 to cut the workpiece 101. In Fig. 22, the cutting tool 1 is moved away while the workpiece 101 is being rotated.

[0087] In the cutting process in the manufacturing method of the embodiment, the cutting tool 1 is moved to bring the cutting tool 1 into contact with the workpiece 101. Furthermore, the cutting tool 1 is moved to separate the cutting tool 1 from the workpiece 101. However, the manufacturing method of the embodiment is not limited to this form.

[0088] For example, in step (1), the workpiece 101 may be brought closer to the cutting tool 1. In step (3), the workpiece 101 may be moved away from the cutting tool 1. When continuing the cutting process, the cutting tool 1 may be kept rotating and the step of bringing the insert into contact with different locations of the workpiece 101 may be repeated.

[0089] Representative examples of the material of the workpiece 101 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0090] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-mentioned embodiments. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art can easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure. [Explanation of symbols]

[0091] 1 cutting tools 3 Holder 5 Insert (Cutting Insert) 7 First screw 9 Second screw 51 Top side 52 Bottom surface 53 Side 531 1st aspect 532 Second side 54 Cutting edge 55 Through hole 56 1st corner 57 Side 1 58 Side 2 59 Second corner 60 Third Side 61 Side 4 62 1st area 63 Second area 64 Recess 65 1st Section 66 Second Section 67 Breaker wall 68 Tip 69 Rear end 70 Part 1 71 Part 2 72 Part 3 73 Part 4 101 Work material 103 Cutting workpiece L1 axis

Claims

1. a top surface having a first corner having a convex curved shape and a first side and a second side extending from the first corner; a lower surface located opposite the upper surface; and A side surface located between the upper surface and the lower surface; A cutting edge located at the first corner and the first side; a through hole opening at the upper surface and the lower surface, The aspect is a first side surface extending from the first edge to the bottom surface; a second side surface extending from the second edge to the bottom surface, When the upper surface is viewed from the front, the upper surface has a shape that is point-symmetric with respect to a center point of the through hole, and a virtual straight line that passes through a tip of the first corner and extends in a long axis direction of the upper surface is referred to as an axis line; The first aspect is A first region having a concave shape recessed toward the axis; a second flat region located farther from the first corner than the first region; The first side is a first section having a concave shape located along the first region; a second section having a linear shape located along the second region, The upper surface is A recess that is recessed toward the axis when the upper surface is viewed from the front; a breaker wall surface located between the first section and the axis, the breaker wall surface moving away from the lower surface as the breaker wall moves away from the first section; The recessed portion is a first recess located between the second side and the axis; a second recess portion located point-symmetrically with respect to the first recess portion with respect to a center point of the through hole; the first recess has a tip end portion that is closest to the first corner in a direction along the axis, the breaker wall has a rear end farthest from the first corner in a direction along the axis, a cutting insert, wherein, in a direction along the axis, the entire first recess is located farther from the first corner than the entire first region, and the rear end portion is located farther from the first corner than the front end portion.

2. an upper surface having first and second corners of a convex curved shape, first and second sides extending from the first corners, and third and fourth sides extending from the second corners; a lower surface located opposite the upper surface; and A side surface located between the upper surface and the lower surface; A first cutting edge located at the first corner and the first side; A second cutting edge located at the second corner and the third side; a through hole opening at the upper surface and the lower surface, The aspect is a first side surface extending from the first edge to the bottom surface; A second side surface extending from the second edge to the bottom surface; a third side surface extending from the third edge to the bottom surface; a fourth side surface extending from the fourth edge to the bottom surface, When the upper surface is viewed from the front, a virtual straight line passing through the tip of the first corner and extending in the major axis direction of the upper surface is referred to as an axis line, The first aspect is A first region having a concave shape recessed toward the axis; a second flat region located farther from the first corner than the first region; The first side is a first section having a concave shape located along the first region; a second section having a linear shape located along the second region, The third aspect is A third region having a concave shape recessed toward the axis; a flat fourth region located farther from the second corner than the third region; The upper surface is A recess that is recessed toward the axis when the upper surface is viewed from the front; a breaker wall surface located between the first section and the axis, the breaker wall surface moving away from the lower surface as the breaker wall moves away from the first section; The recessed portion is a first recess located between the second side and the axis; a second recess located between the fourth side and the axis, the second recess is located on an opposite side of the axis from the first recess, the first recess has a tip end portion that is closest to the first corner in a direction along the axis, the breaker wall has a rear end farthest from the first corner in a direction along the axis, a cutting insert, wherein, in a direction along the axis, the entire first recess is located farther from the first corner than the entire first region, and the rear end portion is located farther from the first corner than the front end portion.

3. When the top surface is viewed from the front, the first section has A linear first portion connected to the first corner; a second portion having a convex curve shape connected to the second section; The cutting insert according to claim 1 or 2, further comprising a third portion having a concave curved shape and located between the first portion and the second portion.

4. When the upper surface is viewed from the front, a radius of curvature of the first corner, which is a convex curved shape, is defined as a first radius of curvature, a radius of curvature of the second portion, which is a convex curved shape, is defined as a second radius of curvature, and a radius of curvature of the third portion, which is a concave curved shape, is defined as a third radius of curvature, The cutting insert according to claim 3 , wherein the first radius of curvature is greater than the second radius of curvature and the third radius of curvature is greater than the first radius of curvature.

5. The first section further includes a fourth portion having a linear shape and located between the second portion and the third portion, When the upper surface is viewed from the front, an inclination angle of the first portion with respect to the axis line is smaller than an inclination angle of the second side with respect to the axis line; an inclination angle of the fourth portion with respect to the axis line is larger than an inclination angle of the second side with respect to the axis line; The cutting insert according to claim 3 or 4, wherein an inclination angle of the second section with respect to the axis is the same as an inclination angle of the second side with respect to the axis.

6. The cutting insert according to claim 5 , wherein the first portion is longer than the fourth portion.

7. a holder having a rod shape extending from a first end to a second end and having a pocket located at the first end; A cutting insert according to any one of claims 1 to 6 located in the pocket; a first screw inserted into the through hole and fixed to the holder; a second screw abutting the second recess and fixed to the holder.

8. Rotating the workpiece; contacting the rotating workpiece with the cutting tool according to claim 7; and removing the cutting tool from the workpiece.

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