Cutting insert

Abstract

To provide a cutting insert which enables suppression of lengthening of a chip, which is therefore improved in treatment of the chip.SOLUTION: The cutting insert comprises a rake face 2 arranged on an upper surface, a seating surface arranged on a lower surface, a flank arranged on an outer peripheral surface, a cutting blade 5 arranged at a ridge line portion at which the rake face 2 is connected to the flank face, and a screw hole. The rake face 2 has: a groove 21 which is arranged inside in a radial direction of the cutting blade 5, dented downward more than the cutting blade 5 and extends in a circumferential direction; a boss surface 22 positioned inside in the radial direction, of the groove 21 and outside in the radial direction, of the screw hole and is arranged at a position upper than the cutting blade 5; a first protrusion portion 23 which is arranged in the groove 21 and protrudes upward more than the cutting blade 5 and whose outer surface is formed into surface 23a curved in convex manner ; a second protrusion portion 24 which protrudes from an outer periphery portion of the boss surface 22 to the outside in the radial direction and is arranged in parallel in the radial direction of the first protrusion portion 23; and joining portion 25 which joins the first 23 and the second protrusion portion 24 arranged adjacently in the radial direction to each other, where a dimension L2 along the circumferential direction, of the first protrusion portion 23 is larger than a dimension L1 along the radial direction, of the first protrusion portion 23.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a cutting insert. [Background technology]

[0002] 2. Description of the Related Art Conventionally, cutting inserts for use in turning tools such as indexable cutting tools are known (for example, see Patent Document 1). The cutting insert of Patent Document 1 has a rake face having a recessed area lower than the cutting edge in the thickness direction, and a plurality of protrusions are formed on the recessed area. All of the plurality of protrusions are connected to each other by intermediate walls. The recessed area has a first region (boss surface) surrounded by the protrusions and the intermediate wall, and a second region located outside the first region. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5110849 Summary of the Invention [Problem to be solved by the invention]

[0004] In the cutting insert of Patent Document 1, the boss surface is lower than the cutting edge, so chips generated by the cutting edge tend to be elongated. The elongated chips may reach the screw hole of the cutting insert, which may cause chip clogging. For this reason, there is room for improvement in terms of improving chip disposal.

[0005] An object of the present invention is to provide a cutting insert capable of suppressing chip elongation and improving chip disposal properties. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides the following means.

[0007] [First aspect of the present invention] A cutting insert having a disk shape centered on a central axis extending in a vertical direction, the cutting insert comprising: a rake face arranged on an upper surface; a seating surface arranged on a lower surface; a relief surface arranged on an outer peripheral surface; a cutting edge arranged on a ridge line portion where the rake face and the relief surface are connected; and a screw hole extending in the vertical direction and opening on the upper surface and the lower surface. The rake face is arranged radially inward of the cutting edge, recessed below the cutting edge, and has a groove extending in the circumferential direction, and a groove extending radially inward of the groove and a diameter of the screw hole. a boss surface located radially outward and positioned above the cutting edge, a first protrusion portion located in the groove, protruding above the cutting edge and having a convex outer surface, a second protrusion portion protruding radially outward from an outer periphery of the boss surface and positioned side by side radially inward of the first protrusion portion, and a connecting portion connecting the first protrusion portion and the second protrusion portion that are adjacent to each other in the radial direction, wherein the dimension of the first protrusion portion along the circumferential direction is greater than the dimension of the first protrusion portion along the radial direction.

[0008] [Aspect 2 of the present invention] The cutting insert of aspect 1, wherein the cutting edge is circular about the central axis, and a plurality of sets of the first protrusion portion, the connecting portion, and the second protrusion portion arranged radially are provided at equal pitch in the circumferential direction.

[0009] [Embodiment 3 of the present invention] 3. The cutting insert according to claim 1 or 2, wherein when a radial dimension of the first protrusion is L1 and a circumferential dimension of the first protrusion is L2, the relationship of [L1<0.8×L2] is satisfied.

[0010] [Embodiment 4 of the present invention] The cutting insert according to any one of aspects 1 to 3, wherein the second protrusion portion has a first curved portion that is curved convex radially outward when viewed from above in a vertical direction, and a pair of second curved portions that are concave curved and extend radially inward as they move away from both circumferential ends of the first curved portion when viewed from above.

[0011] [Embodiment 5 of the present invention] 5. The cutting insert according to any one of aspects 1 to 4, wherein a dimension of the second protrusion along a circumferential direction is greater than a dimension of the first protrusion along a circumferential direction.

[0012] [Aspect 6 of the present invention] The cutting insert according to any one of aspects 1 to 5, wherein when a radial dimension from a radial outer end of the second protrusion portion to the cutting edge is D1, a radial dimension from the center of the radius of curvature of the convex curved surface of the first protrusion portion to the cutting edge is D2, and a radial dimension from an intersection of a virtual plane passing through the cutting edge and perpendicular to the central axis with the first protrusion portion to the cutting edge is D3, the relationship satisfies [D1>D2>D3]. Effect of the Invention

[0013] According to the cutting insert of the above aspect of the present invention, chip elongation can be suppressed, and chip disposal properties can be improved. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a top view showing the cutting insert of the present embodiment. [Diagram 2] FIG. 2 is a side view showing the cutting insert of the present embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing a cross section taken along line III-III in FIG. 1, and more specifically, a vertical cross-sectional view along a predetermined radial direction including the central axis of the cutting insert. [Figure 4] FIG. 4 is an enlarged top view of a portion IV in FIG. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of a portion V in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A cutting insert 1 according to an embodiment of the present invention will be described with reference to the drawings. The cutting insert 1 according to this embodiment is used in a turning tool such as an indexable cutting tool. Although not shown in the drawings, the turning tool includes a rod-shaped holder attached to a tool rest of a lathe, the cutting insert 1 detachably attached to an insert mounting seat formed at the tip of the holder, and a fastening member such as a clamp screw for fixing the cutting insert 1 to the insert mounting seat.

[0016] A turning tool is a cutting tool for turning a workpiece such as a metal. Therefore, the cutting insert 1 of this embodiment may be called a turning insert or a lathe insert. In this embodiment, the cutting insert 1 and the turning tool may be simply called a tool.

[0017] 1 to 3, the cutting insert 1 has a disk shape centered on a central axis O. For this reason, the cutting insert 1 may also be referred to as a round insert or the like. In this embodiment, the direction along the central axis O of the cutting insert 1 is referred to as the up-down direction. That is, the central axis O extends in the up-down direction. In the up-down direction, one side is referred to as the upper side, and the other side is referred to as the lower side.

[0018] Moreover, a direction perpendicular to the central axis O is called a radial direction. Of the radial directions, a direction approaching the central axis O is called a radially inner direction, and a direction away from the central axis O is called a radially outer direction. Moreover, the direction rotating around the central axis O is called the circumferential direction.

[0019] In this embodiment, the terms "up-down direction," "upper side," and "lower side" are convenient names for easily explaining the relative positional relationship of each component of the cutting insert 1. Therefore, the actual positional relationship when the tool is used, etc., is not limited by these names.

[0020] The cutting insert 1 is made of, for example, a cemented carbide alloy. The cutting insert 1 is formed in a rotationally symmetric shape with a predetermined angle (central angle) centered on the central axis O. The cutting insert 1 of this embodiment has, for example, a rotationally symmetric shape with a central angle of 30° (12-fold symmetric shape). The cutting insert 1 is not inverted symmetric in the up-down direction. The cutting insert 1 of this embodiment is a so-called one-sided type positive insert with a clearance angle provided on the outer peripheral surface.

[0021] The cutting insert 1 has a pair of plate surfaces (upper and lower surfaces) facing the vertical direction, and an outer peripheral surface facing radially outward and extending in the circumferential direction. The cutting insert 1 also has a rake face 2 arranged on the upper surface, a seating surface 3 arranged on the lower surface, a flank face 4 arranged on the outer peripheral surface, a cutting edge 5 arranged on a ridge portion connecting the rake face 2 and the flank face 4, and a screw hole 6 penetrating the cutting insert 1 in the vertical direction.

[0022] The rake face 2 is provided on an upward-facing plate surface, i.e., an upper surface, of the cutting insert 1. As shown in Figs. 1 to 5, the rake face 2 has a groove 21, a boss surface 22, a first protrusion 23, a second protrusion 24, a connecting portion 25, and a corner mark 26.

[0023] The groove 21 is disposed radially inward of the cutting edge 5. The groove 21 is recessed downward from the cutting edge 5 and extends circumferentially along the cutting edge 5. The groove 21 is annular about the central axis O, and specifically, has a circular ring shape in the top view shown in Fig. 1. The groove 21 may also be referred to as a breaker groove or the like.

[0024] The boss surface 22 is located radially inward of the groove 21 and radially outward of the screw hole 6. The boss surface 22 is annular about the central axis O, and more specifically, has a circular ring shape in the top view shown in FIG. 1. As shown in FIG. 5, the boss surface 22 is disposed above the cutting edge 5. The boss surface 22 has a planar shape that extends in a direction perpendicular to the central axis O.

[0025] 1, 4, and 5, the first protrusion 23 is disposed in the groove 21. The first protrusion 23 protrudes from the bottom surface of the groove 21 and protrudes upward beyond the cutting edge 5. The first protrusion 23 has an elliptical or oval shape that is longer in the circumferential direction than in the radial direction when viewed from above in the vertical direction as shown in FIGS. 1 and 4. That is, the dimension (L2) of the first protrusion 23 in the circumferential direction is greater than the dimension (L1) of the first protrusion 23 in the radial direction.

[0026] When the radial dimension of the first protrusion 23 is L1 and the circumferential dimension of the first protrusion 23 is L2, the first protrusion 23 satisfies the relationship [L1<0.8×L2]. In this embodiment, for example, [L1=0.6×L2].

[0027] In addition, in this embodiment, when viewed from above, the radially outer end of the first protrusion portion 23 is curved and convex radially outward, and the radially inner end of the first protrusion portion 23 is approximately straight and extends in the circumferential direction.

[0028] As shown in Fig. 5, the outer surface (front surface) of the first protrusion 23 is a convex curved surface 23a. The convex curved surface 23a has a convex curved shape in both a vertical cross section along the radial direction shown in Fig. 5 and a vertical cross section along the circumferential direction (not shown). In the vertical cross section shown in Fig. 5, the radius of curvature R of the convex curved surface 23a is, for example, 0.9 mm or more and 1.2 mm or less.

[0029] The center C of the curvature radius R of the convex curved surface 23a is located below the cutting edge 5. In this embodiment, the center C of the curvature radius R of the convex curved surface 23a is located radially outward from the second protrusion 24.

[0030] 4, the second protrusion 24 protrudes radially outward from the outer periphery of the boss surface 22. The second protrusion 24 has a convex shape that protrudes radially outward from the outer periphery of the boss surface 22. For this reason, the second protrusion 24 may be referred to as a protruding portion or the like. The second protrusion 24 is disposed radially inward of the first protrusion 23 and aligned with the first protrusion 23.

[0031] The circumferential dimension of the second protrusion 24 decreases radially outward. The circumferential dimension L3 (maximum value) of the second protrusion 24 is greater than the circumferential dimension L2 of the first protrusion 23.

[0032] 4 represents a center line CL that extends along the radial direction and passes through the circumferential centers of the first protrusion 23 and the second protrusion 24. The first protrusion 23 and the second protrusion 24 are closest in the radial direction on the center line CL, and the distance between them (radial distance) increases as they move away from the center line CL in the circumferential direction.

[0033] The second protrusion 24 has a first curved portion 24a disposed at a radially outer end of the second protrusion 24, and a pair of second curved portions 24b connected to both ends of the first curved portion 24a. The first curved portion 24a has a curved shape that is convex radially outward in a top view seen from the up-down direction as shown in Fig. 4. The pair of second curved portions 24b have a concave curved shape that extends radially inward as it moves away from both circumferential ends of the first curved portion 24a in the circumferential direction in this top view.

[0034] 4, the radius of curvature of the second curved portion 24b is larger than the radius of curvature of the first curved portion 24a. Specifically, in this top view, the radius of curvature of the first curved portion 24a is, for example, 0.4 mm or more and 0.6 mm or less, and the radius of curvature of the second curved portion 24b is, for example, 1.5 mm or more and 2.5 mm or less.

[0035] 5, the upper end surface of the second protrusion 24 is flat and extends in a direction perpendicular to the central axis O. The upper end surface of the second protrusion 24 and the boss surface 22 are formed on the same plane. That is, the upper end surface of the second protrusion 24 and the boss surface 22 are formed flush with each other.

[0036] In this embodiment, the amount of protrusion h2 by which the second protrusion 24 protrudes upward from the cutting edge 5 is set to be larger than the amount of protrusion h1 by which the first protrusion 23 protrudes upward from the cutting edge 5. In other words, the upper end surface of the second protrusion 24 is disposed above the upper end (top) of the first protrusion 23.

[0037] Also, in Figure 5, when the radial dimension from the radial outer end of the second protrusion 24 to the cutting edge 5 is D1, the radial dimension from the center C of the radius of curvature R of the convex curved surface 23a of the first protrusion 23 to the cutting edge 5 is D2, and the radial dimension from the intersection P of a virtual plane VS that passes through the cutting edge 5 and is perpendicular to the central axis O with the first protrusion 23 to the cutting edge 5 is D3, the cutting insert 1 of this embodiment satisfies the relationship [D1>D2>D3].

[0038] As shown in FIG. 4, the connecting portion 25 is disposed in the groove 21. The connecting portion 25 protrudes from the bottom surface of the groove 21 and is disposed between the first protrusion 23 and the second protrusion 24 which are arranged in the radial direction. The connecting portion 25 extends in the circumferential direction between the first protrusion 23 and the second protrusion 24. The connecting portion 25 connects the first protrusion 23 and the second protrusion 24 which are adjacent in the radial direction. A radially inner end of the connecting portion 25 is connected to a radially outer end of the second protrusion 24, and a radially outer end of the connecting portion 25 is connected to a radially inner end of the first protrusion 23.

[0039] The circumferential dimension of the connecting portion 25 becomes smaller from the connection portion with the second protrusion 24 to the connection portion with the first protrusion 23 (that is, toward the radially outer side). In addition, the upper end of the connecting portion 25 is located lower than the upper ends of the first protrusion 23 and the second protrusion 24. In other words, the height of the connecting portion 25 in the up-down direction is lower than the height of the first protrusion 23 and the second protrusion 24 in the up-down direction.

[0040] The connecting portion 25 extends downward as it moves away in the circumferential direction from the circumferential position (i.e., on the center line CL) where the first protrusion 23 and the second protrusion 24 are closest to each other. In addition, in a portion of the connecting portion 25 that overlaps with the first protrusion 23 when viewed from the radial direction (the central portion of the connecting portion 25 in the circumferential direction), the radial dimension of the connecting portion 25 increases as it moves away in the circumferential direction from the center line CL. In addition, in a portion of the connecting portion 25 that does not overlap with the first protrusion 23 when viewed from the radial direction (both ends of the connecting portion 25 in the circumferential direction), the radial dimension of the connecting portion 25 decreases as it moves away in the circumferential direction from the center line CL.

[0041] As shown in Fig. 1, a plurality of sets S of the first protrusions 23, the connecting portions 25, and the second protrusions 24 arranged in the radial direction are provided at equal pitches in the circumferential direction. That is, a plurality of the first protrusions 23, the connecting portions 25, and the second protrusions 24 are each provided at equal pitches around the central axis O. In this embodiment, 12 sets S of the first protrusions 23, the connecting portions 25, and the second protrusions 24 arranged in the radial direction are provided at equal pitches of a central angle of 30° about the central axis O in a top view seen from the vertical direction as shown in Fig. 1.

[0042] The corner marks 26 are disposed on the boss surface 22. A plurality of (e.g., three or more) corner marks 26 are provided at intervals from one another in the circumferential direction. The number of corner marks 26 is, for example, a divisor of the number of sets S. In this embodiment, three corner marks 26 are provided at a pitch of 120° at a central angle about the central axis O.

[0043] Each corner mark 26 is displayed so as to be identifiable, for example, by a symbol or a number. In this embodiment, each corner mark 26 is identifiable by the number of "●" marks (1 to 3). By providing such corner marks 26, the user can easily distinguish between used and unused portions of the cutting blade 5.

[0044] 2 and 3, the seating surface 3 is provided on a plate surface facing downward, i.e., the lower surface, of the cutting insert 1. The seating surface 3 is flat and extends in a direction perpendicular to the central axis O. The seating surface 3 is a surface that is seated on an insert mounting seat of a holder (not shown). In this embodiment, the seating surface 3 and the boss surface 22 are parallel to each other.

[0045] The flank 4 is disposed on an annular outer peripheral surface extending around the central axis O. The flank 4 is disposed at least at the upper end of the outer peripheral surface. The flank 4 is disposed below the cutting edge 5 and adjacent to the cutting edge 5. The flank 4 extends in the circumferential direction along the cutting edge 5. The flank 4 also extends radially inward as it moves downward from the cutting edge 5. In other words, the flank 4 has a tapered surface shape that reduces in diameter as it moves downward from the cutting edge 5. This makes it easy to provide a clearance angle between the processing surface of the workpiece and the flank 4 during cutting, and increases the degree of freedom in the mounting posture of the cutting insert 1 to the holder.

[0046] As shown in Figs. 1 and 5, the cutting edge 5 is disposed on a ridge line where the outer periphery of the groove 21 on the rake face 2 and the upper end of the flank 4 are connected. The cutting edge 5 is annular about the central axis O, and specifically, has a circular shape. In this embodiment, the cutting edge 5 is disposed over its entire circumference on a virtual plane VS that extends in a direction perpendicular to the central axis O (see Fig. 5). In other words, the vertical position of the cutting edge 5 is constant over the entire circumference around the central axis O.

[0047] 1 and 3, the screw hole 6 extends in the vertical direction inside the cutting insert 1 and opens to the upper and lower surfaces of the cutting insert 1. The screw hole 6 has a circular cross section perpendicular to the central axis O. The central axis of the screw hole 6 is arranged coaxially with the central axis O. In this embodiment, the inner diameter of the upper end of the screw hole 6 is larger than the inner diameter of the portion of the screw hole 6 other than the upper end.

[0048] In the cutting insert 1 of this embodiment described above, the boss surface 22 protrudes above the cutting edge 5 (i.e., is disposed at a higher position), so that chips generated by the cutting edge 5 are easily folded and broken stably before flowing over the rake face 2 and reaching the boss surface 22. Since the chips are prevented from extending, the chips are prevented from reaching the screw hole 6 beyond the boss surface 22. This prevents chip clogging. In addition, wear caused by the chips rubbing against fastening members such as clamp screws is also prevented.

[0049] In addition, the chips generated by the cutting edge 5 flow within the groove 21 on the cutting face 2, and as they come into contact with the first protrusion 23, the connecting portion 25 or the second protrusion 24, they are curled or broken, and the flow direction (chip flow) is controlled.

[0050] Specifically, when chips move radially inward from the cutting edge 5, the chips come into stable contact with the first protrusion 23, which has a circumferential dimension L2 larger than the radial dimension L1 (is wider in the circumferential direction), thereby controlling the chip flow. Furthermore, when chips flow in the circumferential direction from the cutting blade 5, the chips are stably contacted with at least one of the first protrusions 23, the connecting portions 25, and the second protrusions 24 arranged in the radial direction, thereby controlling the chip flow. Furthermore, by providing the connecting portions 25, the present embodiment suppresses problems such as chip clogging between the first protrusions 23 and the second protrusions 24, as compared to a configuration in which the connecting portions 25 are not provided between the first protrusions 23 and the second protrusions 24, for example.

[0051] As described above, according to the cutting insert 1 of the present embodiment, chip elongation can be suppressed, and chip disposal performance can be stably improved.

[0052] In this embodiment, the set S of the first protrusion 23, the connecting portion 25, and the second protrusion 24 is arranged to extend in the radial direction, thereby ensuring the strength of the set S against external forces of chips acting on the set S from the radial outside. Also, the first protrusion 23, the connecting portion 25, and the second protrusion 24 are each formed to extend in the circumferential direction, thereby ensuring the strength of each component of the set S (the first protrusion 23, the connecting portion 25, or the second protrusion 24) against external forces of chips acting on the set S from the circumferential direction. Therefore, damage to the first protrusions 23, the connecting portions 25 and the second protrusions 24 is suppressed, and the above-mentioned excellent chip disposal properties are well maintained for a long period of time.

[0053] In this embodiment, the cutting edge 5 has a circular shape centered on the central axis O, and a plurality of sets S of the first protrusions 23, the connecting portions 25, and the second protrusions 24 arranged radially are provided at equal pitches in the circumferential direction. The sets S are preferably formed at equal pitch intervals such that the central angle about the central axis O is 25° or more and 40° or less when viewed from above in the vertical direction. In this case, the cutting blade 5 can be used for turning over its entire circumference, and the tool life is extended. Furthermore, the above-mentioned first protrusion 23, the connecting portion 25, and the second protrusion 24 provide stable effects at each circumferential position of the cutting blade 5 used for cutting.

[0054] In this embodiment, the radial dimension L1 and the circumferential dimension L2 of the first protrusion 23 satisfy the relationship [L1<0.8×L2]. As described above, when the radial dimension L1 of the first protrusion 23 is less than 0.8 times the circumferential dimension L2 of the first protrusion 23, it is possible to ensure a sufficiently large circumferential dimension L2 of the first protrusion 23. This makes it possible for chips to stably contact the first protrusion 23 from the radial outside, and allows for good control of the chip flow.

[0055] In addition, in this embodiment, the second protrusion portion 24 has a first curved portion 24a that is curved in a convex manner radially outward when viewed from above in the vertical direction, and a pair of second curved portions 24b that are concave curved and extend radially inward as they move away from both circumferential ends of the first curved portion 24a when viewed from above. In this case, the first curved portion 24a, which is a convex curved portion in a top view, and the pair of second curved portions 24b, which are concave curved portions, can be smoothly connected without any steps. This makes it difficult for bends or sharp corners to be formed in the second protrusions 24, and prevents a large force from acting locally on the second protrusions 24 from the cutting chips, thereby suppressing damage to the second protrusions 24.

[0056] In this embodiment, the dimension L3 of the second protrusion 24 along the circumferential direction is greater than the dimension L2 of the first protrusion 23 along the circumferential direction. In this case, the second protrusion 24 can stably support the first protrusion 23 from the radially inner side over the entire circumferential area via the connecting portion 25. This stably suppresses damage to the first protrusion 23, etc.

[0057] In addition, in this embodiment, the radial dimension D1 from the radial outer end of the second protrusion 24 to the cutting edge 5, the radial dimension D2 from the center C of the radius of curvature R of the convex curved surface 23a of the first protrusion 23 to the cutting edge 5, and the radial dimension D3 from the intersection P of a virtual plane VS that passes through the cutting edge 5 and is perpendicular to the central axis O and the first protrusion 23 to the cutting edge 5 satisfy the relationship [D1>D2>D3]. In this case, since the radial dimension D1 is ensured to be sufficiently large, the occurrence of chip clogging between the cutting edge 5 and the second protrusion 24 is reliably prevented.

[0058] In this embodiment, the amount of projection h2 by which the second projection 24 projects upward from the cutting edge 5 is set to be larger than the amount of projection h1 by which the first projection 23 projects upward from the cutting edge 5. According to the above configuration, even if the chips go over the first protrusion 23 radially inward, the chip flow can be controlled by making the chips contact the second protrusion 24 that protrudes upward from the first protrusion 23. Therefore, the chip disposal performance can be improved more stably.

[0059] The present invention is not limited to the above-described embodiment, and the configuration may be modified within the scope of the present invention, for example as described below.

[0060] In the above embodiment, an example was given in which 12 sets S of the first protrusions 23, the connecting portions 25, and the second protrusions 24 arranged in the radial direction are provided at equal pitches of a central angle of 30° about the central axis O in a top view seen from the vertical direction, but this is not limited to this. The arrangement and number of the sets S can be appropriately changed depending on, for example, the type, shape, cutting conditions, etc. of the workpiece.

[0061] In the above embodiment, three corner marks 26 are provided at a pitch of 120° about the central axis O, but the present invention is not limited to this. The arrangement and number of corner marks 26 can be changed as appropriate depending on, for example, the type, shape, and cutting conditions of the workpiece. The number of corner marks 26 is not limited to a divisor of the number of sets S.

[0062] The present invention may be combined with the various configurations described in the above-mentioned embodiments and modifications, and may include additions, omissions, substitutions, and other modifications, without departing from the spirit of the present invention. The present invention is not limited to the above-mentioned embodiments, but is limited only by the claims. [Industrial Applicability]

[0063] INDUSTRIAL APPLICABILITY The cutting insert of the present invention can suppress chip elongation and improve chip disposal properties, and therefore has industrial applicability. [Explanation of symbols]

[0064] 1...cutting insert, 2...rake face, 3...seating surface, 4...flank face, 5...cutting edge, 6...screw hole, 21...groove, 22...boss surface, 23...first protrusion, 23a...convex surface, 24...second protrusion, 24a...first curved portion, 24b...second curved portion, 25...connecting portion, C...center of radius of curvature of convex surface, D1, D2, D3...radial dimension, L1...radial dimension of first protrusion, L2...circumferential dimension of first protrusion, L3...circumferential dimension of second protrusion, O...center axis, P...intersection, R...radius of curvature of convex surface, S...set, VS...imaginary plane

Claims

1. A cutting insert having a disk shape centered on a central axis extending in the vertical direction, A scooping surface disposed on the upper surface; A seating surface disposed on the lower surface; A flank surface disposed on the outer peripheral surface; A cutting edge is disposed on a ridge portion where the rake face and the flank face are connected; a screw hole extending in a vertical direction and opening to the upper surface and the lower surface; The rake face is A groove is disposed radially inside the cutting edge, recessed below the cutting edge, and extending in a circumferential direction; A boss surface is located radially inward of the groove and radially outward of the screw hole, and is disposed above the cutting edge; A first protrusion portion is disposed in the groove, protrudes above the cutting edge, and has an outer surface that is a convex curved surface; A second protrusion protruding radially outward from an outer periphery of the boss surface and arranged side by side radially inward of the first protrusion; a connecting portion connecting the first protrusion and the second protrusion adjacent to each other in the radial direction, A dimension of the first protrusion along a circumferential direction is larger than a dimension of the first protrusion along a radial direction. Cutting insert.

2. The cutting edge has a circular shape centered on the central axis, A plurality of sets of the first protrusion, the connecting portion, and the second protrusion arranged in a radial direction are provided at equal pitches in a circumferential direction. The cutting insert according to claim 1 .

3. A radial dimension of the first protrusion is L1, When the circumferential dimension of the first protrusion is L2, The relationship of [L1 < 0.8 × L2] is satisfied. The cutting insert according to claim 1 or 2.

4. The second protrusion portion is A first curved portion having a curved shape that is convex toward a radially outward direction when viewed from a top view in the vertical direction; A pair of second curved portions having a concave curved shape extending radially inward as they move away from both circumferential ends of the first curved portion in the top view. The cutting insert according to claim 1 or 2.

5. The dimension of the second protrusion along the circumferential direction is larger than the dimension of the first protrusion along the circumferential direction. The cutting insert according to claim 1 or 2.

6. A radial dimension from a radial outer end of the second protrusion to the cutting edge is defined as D1, A radial dimension from the center of the curvature radius of the convex curved surface of the first protrusion to the cutting edge is D2, When a radial dimension from an intersection point of a virtual plane passing through the cutting edge and perpendicular to the central axis with the first protrusion to the cutting edge is D3, The relationship of [D1>D2>D3] is satisfied. The cutting insert according to claim 1 or 2.

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