Cutting tool

Abstract

To provide a cutting tool which can stably enhance a cutting chip processing property at the time of low cutting.SOLUTION: A cutting tool includes a rake face 1, a flank, a cutting blade 3 having a V shape in plan view when the rake face 1 is viewed in the front, a chip breaker 4, and projections 5 projecting from the rake face 1, wherein the cutting blade 3 has a corner blade 3a and a pair of straight blades 3b, the rake face 1 has a corner rake face 18 connected to the corner blade 3a, and a pair of straight rake faces 19 connected to the pair of straight blades 3b, the chip breaker 4 extends in a back and forth direction, at least a pair of the projections 5 is provided on a left side and a right side of a bisector B in plan view, each of the projections 5 is arranged in at least one of the corner rake face 18 and a front end of the straight rake face 19, and extends in a direction crossing the cutting blade 3 in plan view, and out of a pair of projection side faces 51 and 52 directed in a direction crossing the extension direction of the projection 5 in plan view, the one projection side face 51 has a convex curved surface 51a, and the other projection side face 52 has a concave curved surface 52a.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, cutting tools such as cutting inserts used in turning a workpiece such as a metal are known (see, for example, Patent Documents 1 and 2). This type of cutting tool has a rake face, a flank, a cutting edge that is arranged on the ridge where the rake face and the flank face are connected and that is V-shaped in a plan view when the rake face is seen from the front, and a chip breaker that is arranged on the inside of the rake face in a plan view. Attempts have been made to improve the breakability and dischargeability of chips (hereinafter referred to as chip disposal performance) by devising the shape of the chip breaker. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 035490 [Patent Document 2] Patent No. 7094501 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional cutting tools, when the depth of cut is small, the chips tend to be irregularly shaped and stretched, and may become entangled in the chuck of the lathe, etc. For this reason, there is room for improvement in terms of more stable chip disposal, especially when the depth of cut is small.

[0005] An object of the present invention is to provide a cutting tool that can stably improve chip disposal performance at a small depth of cut. [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 edge that is arranged on a ridge line portion where the cutting face and the flank are connected and that has a V-shape in a plan view when the cutting face is viewed from the front; a chip breaker that is arranged inside the cutting face in the plan view; and a protrusion that is arranged on the cutting face and protrudes from the cutting face, wherein the cutting edge has a corner blade that has a convex curved shape, and a pair of straight blades that are connected to both ends of the corner blade and each extend linearly, and the direction in which a bisector of the pair of straight blades extends in the plan view is defined as a front-rear direction, a direction perpendicular to the bisector in the plan view is defined as a left-right direction, and a direction perpendicular to the front-rear direction and the left-right direction is defined as a top-bottom direction. a cutting tool comprising: a cutting surface having a corner cutting edge connected to the corner blade and a pair of straight cutting edges connected to the pair of straight blades; the chip breaker is arranged on the bisector in the planar view and extends in the front-to-rear direction; at least a pair of protrusions are provided on the left and right sides of the bisector in the planar view; each protrusion is arranged on at least one of the corner cutting surface and the front end portion of the straight cutting surface, and extends in a direction intersecting with the cutting edge in the planar view; and one protrusion side surface has a convex curved surface and the other protrusion side surface has a concave curved surface.

[0008] The cutting tool of the present invention is, for example, a cutting insert for an indexable cutting tool used in turning (lathe) processing. In this cutting tool, a chip breaker is disposed on the inside of the rake face, and at least a pair of protrusions is disposed on the rake face. Specifically, each protrusion is disposed on at least one of the corner rake face and the front end of the straight rake face, and is located at the tip of the tool including the nose R.

[0009] When this cutting tool is used to turn a workpiece, at high depths of cut, the chips come into contact with the chip breaker and are broken stably. Specifically, in this specification, "large depths of cut" means, for example, that the depth of cut ap is 0.5 mm or more.

[0010] On the other hand, when the cutting depth is small, the chips are unlikely to come into contact with the chip breaker that extends along a bisecting line in a plan view. Therefore, in the present invention, when the cutting depth is small, the chips are made to come into contact with the protrusions near the nose R. The chips are stably broken up by contacting the protrusions, or even if they are not broken up, they are curled into a regular spiral shape or the like, and are well disposed of. Specifically, in this specification, "a small cutting depth" means, for example, that the cutting depth ap is about 0.1 mm.

[0011] In this way, the cutting tool of the present invention can prevent chips from easily stretching into irregular shapes when the cutting depth is low, and can stably prevent problems such as the chips becoming entangled in the chuck of a lathe, etc. In other words, it is possible to stably improve chip disposability not only when the cutting depth is high, but also when the cutting depth is low.

[0012] In addition, for example, when the angle (cutting edge rhombus) formed between the pair of straight blades in a plan view is large, or when the nose R (curvature radius of the corner blade) is large, the distance between the cutting edge and the chip breaker tends to be large. In such a configuration, even if the cutting depth is not reduced, the chips may not easily come into contact with the chip breaker. On the other hand, according to the present invention, even in the above configuration, the chips are stably brought into contact with the protrusions, and chip disposal is stably improved.

[0013] Moreover, of the pair of protrusion side surfaces that each protrusion has, one is provided with a convex curved surface, and the other is provided with a concave curved surface. When the cutting conditions, etc. are set so that the chips come into contact with the convex curved surface of the protrusion, the strength of the protrusion is increased, so that damage to the protrusion, etc. is suppressed. The effect of the protrusion is stable over a long period of time. Furthermore, when the cutting conditions, etc. are set so that the chips come into contact with the concave curved surface of the protrusion, it becomes easier to control the flow direction of the chips, and chip discharge performance is improved.

[0014] [Aspect 2 of the present invention] 2. The cutting tool of claim 1, wherein the one protrusion side faces a front side and the other protrusion side faces a rear side.

[0015] In this case, during turning by pushing the nose R forward against the workpiece, the chips come into contact with the convex curved surface on one side of the protrusion. Generally, turning is mainly performed by pushing, which increases the strength of the protrusion and further prevents damage to the protrusion.

[0016] In addition, during turning by pulling, which retracts the nose R against the workpiece, the chips come into contact with the concave curved surface of the other protrusion side. This makes it possible to more stably improve chip disposal during the pulling process.

[0017] [Embodiment 3 of the present invention] 3. The cutting tool according to claim 1 or 2, wherein the one protrusion side surface further has a connecting concave curved surface that smoothly connects the convex curved surface and the cutting surface.

[0018] In this case, the connecting concave surface smoothly connects the convex surface and the rake face. The connecting concave surface further increases the strength of the protrusion. The connecting concave surface also makes it difficult for chips to get caught on the protrusion, and the chips are guided more stably toward the convex surface.

[0019] [Embodiment 4 of the present invention] 4. The cutting tool of any one of aspects 1 to 3, wherein the cutting face has a land connected to the cutting edge and extending along the cutting edge, the land having a V-shape in the planar view, and an outer end of the protrusion along the extension direction is connected to the land.

[0020] In this case, the outer end of the projection in the extending direction reaches the land adjacent to the cutting edge, so that even if the cutting depth during cutting is small, the chips are more likely to come into contact with the projection, and the above-mentioned action and effect of the projection are more stably achieved.

[0021] [Embodiment 5 of the present invention] A cutting tool according to any one of aspects 1 to 4, wherein an inner end of the protrusion along the extension direction is positioned away from the chip breaker.

[0022] For example, in a configuration in which the inner end of the projection in the extending direction is connected to the chip breaker, chip clogging may occur near the connection between the projection and the chip breaker. On the other hand, according to the above configuration of the present invention, chips can pass between the inner end of the projection in the extending direction and the chip breaker, so that the above-mentioned chip clogging can be suppressed.

[0023] [Aspect 6 of the present invention] 6. The cutting tool according to any one of aspects 1 to 5, wherein the chip breaker has a breaker wall surface facing outward in the left-right direction and a breaker bottom surface located between the breaker wall surface and the cutting face, the breaker wall surface having a first wall surface extending outward in the left-right direction toward the rear side and a second wall surface located rearward of the first wall surface and extending outward in the left-right direction toward the rear side, wherein a second opening angle formed between the second wall surface and the bisector is larger than a first opening angle formed between the first wall surface and the bisector in the plan view, and an extension direction of the protrusion is perpendicular to the first wall surface or the second wall surface in the plan view.

[0024] In this case, the function of the protrusion is stable. If the position of the inner end of the protrusion in the extension direction is the same, it is more preferable that the extension direction of the protrusion is perpendicular to the second wall surface. If the extension direction of the protrusion is perpendicular to the second wall surface, the outer end of the protrusion in the extension direction is located further forward (nose R side), and the protrusion is stably contacted by the chips at a small cutting depth.

[0025] [Seventh aspect of the present invention] the chip breaker has a breaker wall surface facing outward in the left-right direction and a breaker bottom surface located between the breaker wall surface and the cutting face, the breaker wall surface having a first wall surface extending outward in the left-right direction toward the rear side and a second wall surface located rearward of the first wall surface and extending outward in the left-right direction toward the rear side, a second opening angle formed between the second wall surface and the bisector is larger than a first opening angle formed between the first wall surface and the bisector in the plan view, and an angle formed between an extension direction of the protrusion and the bisector is smaller than an angle formed between a virtual straight line perpendicular to the second wall surface and the bisector in the plan view.

[0026] In this case, it becomes easy to dispose the outer end of the projection in the extending direction further forward in the vicinity of the nose R. This makes it possible to more stably improve chip discharge performance when the cutting depth is small.

[0027] [Embodiment 8 of the present invention] A cutting tool according to any one of aspects 1 to 7, wherein a front end of the chip breaker is disposed between a pair of the protrusions provided on the left and right sides of the bisector.

[0028] In this case, by appropriately utilizing the pair of protrusions arranged near the nose R and the front end of the chip breaker, it is possible to accommodate low cutting depth machining under a variety of cutting conditions.

[0029] [Embodiment 9 of the present invention] A cutting tool according to any one of aspects 1 to 8, wherein the protrusions are arranged side by side along a blade length direction in which the cutting edge extends, on the left or right side of the bisector in the plan view.

[0030] In this case, multiple protrusions are arranged in a row along the cutting edge length direction on the left or right side of the bisector near the nose R. This makes it possible to handle low-depth cutting under various cutting conditions. The extension directions of the multiple protrusions may be parallel to each other or may be different from each other.

[0031] [Aspect 10 of the present invention] 10. The cutting tool of any one of aspects 1 to 9, wherein the chip breaker has a breaker wall surface facing outward in the left-right direction and a breaker bottom surface disposed between the breaker wall surface and the cutting face, the breaker bottom surface having a plurality of coolant grooves extending thereon, the plurality of coolant grooves extending in a direction intersecting the left-right direction in the planar view.

[0032] During cutting using the cutting tool of the present invention, chips generated by the cutting blade flow out, for example, in a generally left-right direction. If the multiple coolant grooves provided on the bottom surface of the breaker extend in a direction intersecting the left-right direction as in the above configuration, the coolant flowing through the coolant grooves is less affected by the chips. This makes it easier to spread the coolant over a wide area on the bottom surface of the breaker, and also makes it easier to ensure a large liquid film thickness. The lubricity of the coolant is increased, and cutting resistance is reduced. Furthermore, the occurrence of welding can also be suppressed.

[0033] [Embodiment 11 of the present invention] 11. The cutting tool according to any one of aspects 1 to 10, comprising a cutting portion on which the cutting face, the flank, the cutting edge, the chip breaker and the protrusion are arranged, the cutting portion being made of a cBN sintered body or a diamond sintered body.

[0034] In this case, since the hardness of the blade portion is increased, even when cutting a workpiece such as a hard and brittle material, wear and damage to the cutting edge, protrusions and chip breaker are reduced, making it possible to perform stable cutting. Effect of the Invention

[0035] According to the cutting tool of the above aspect of the present invention, chip disposal performance at a small depth of cut can be stably improved. [Brief description of the drawings]

[0036] [Figure 1] FIG. 1 is a perspective view showing a cutting tool according to the present embodiment. [Diagram 2] FIG. 2 is a perspective view showing a part of the cutting tool (near the cutting edge), and the coolant grooves are not shown. [Diagram 3] FIG. 3 is a top view showing a part of the cutting tool (near the cutting edge), and the coolant grooves are not shown. [Figure 4] FIG. 4 is a cross-sectional view showing a cross section taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is a cross-sectional view showing a VV section of FIG. 3, and the illustration of the coolant grooves is omitted. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 3, and the coolant grooves are omitted. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 3, and the coolant grooves are omitted. [Figure 8] FIG. 8 is a perspective view showing a part of the cutting tool (near the blade portion), with protrusions not shown. [Figure 9] FIG. 9 is a top view showing a part (near the cutting edge) of a cutting tool according to a first modified example of this embodiment, with the coolant grooves omitted. [Figure 10] FIG. 10 is a top view showing a part (near the cutting edge) of a cutting tool according to a second modified example of this embodiment, with the coolant grooves omitted. [Figure 11]FIG. 11 is a top view showing a part (near the cutting edge) of a cutting tool according to a third modified example of this embodiment, with the coolant grooves omitted. [Figure 12] FIG. 12 is a top view showing a part (near the cutting edge) of a cutting tool according to a fourth modified example of this embodiment, with the coolant grooves omitted. [Figure 13] FIG. 13 is a top view showing a part (near the cutting edge) of a cutting tool according to a fifth modified example of this embodiment, with the coolant grooves omitted. [Figure 14] FIG. 14 is a top view showing a part (near the cutting edge) of a cutting tool according to a sixth modified example of this embodiment, with the coolant grooves omitted. [Figure 15] FIG. 15 is a top view showing a part (near the cutting edge) of a cutting tool according to a seventh modified example of this embodiment, with the coolant grooves omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] A cutting tool 10 according to an embodiment of the present invention will be described with reference to Fig. 1 to Fig. 8. The cutting tool 10 according to the present embodiment is a cutting insert used in an indexable cutting tool for turning (cutting) a workpiece made of metal, for example. In the present embodiment, the cutting tool 10 may be simply referred to as a tool.

[0038] Although not specifically shown, the indexable cutting tool includes a holder and a cutting tool (cutting insert) 10. The holder is made of, for example, steel and has a columnar shape. The holder has a concave insert mounting seat that is disposed at the tip of the holder. The cutting tool 10 is removably attached to the insert mounting seat.

[0039] As shown in FIG. 1, the cutting tool 10 is plate-shaped. In this embodiment, the cutting tool 10 is polygonal plate-shaped, specifically, quadrangular plate-shaped such as diamond-shaped plate-shaped. More specifically, the cutting tool 10 of this embodiment is, for example, a diamond-shaped insert (cutting insert) conforming to a general ISO standard. However, the cutting tool 10 is not limited thereto, and may be polygonal plate-shaped such as triangular plate-shaped, pentagonal plate-shaped, hexagonal plate-shaped, or the like.

[0040] The cutting tool 10 is a polygonal plate centered on the insert central axis C, and a pair of plate surfaces (front and back) thereof face in the direction in which the insert central axis C extends (the insert axial direction). In this embodiment, the direction perpendicular to the insert central axis C may be referred to as the insert radial direction, and the direction circumferential around the insert central axis C may be referred to as the insert circumferential direction. Within the insert radial direction, the direction approaching the insert central axis C is the inner side of the insert radial direction, and the direction away from the insert central axis C is the outer side of the insert radial direction.

[0041] The cutting tool 10 includes a base metal portion 11 and a cutting edge portion 12 . The base metal portion 11 is made of, for example, a cemented carbide alloy. The base metal portion 11 has a polygonal plate shape, and in this embodiment, a quadrangular plate shape such as a diamond plate shape. The base metal portion 11 has a blade portion attachment portion 11a and an attachment hole 11b.

[0042] The blade attachment portion 11a is recessed from one of a pair of plate surfaces (front and back surfaces) of the base metal portion 11 and from the outer circumferential surface. In this embodiment, the blade attachment portion 11a is triangular recessed. The blade attachment portion 11a is disposed at a predetermined corner among multiple corners of the base metal portion 11.

[0043] The mounting hole 11b penetrates the base metal portion 11 in the insert axial direction and opens to a pair of plate surfaces (front and back surfaces) of the base metal portion 11. The mounting hole 11b is a circular hole centered on the insert central axis C. A clamp piece, a clamp screw, or the like (not shown) for fixing the cutting tool 10 to an insert mounting seat of a holder is inserted into the mounting hole 11b.

[0044] The blade portion 12 is fixed (joined) to the blade portion attachment portion 11a by a predetermined joining means or the like. That is, the blade portion 12 is disposed at a predetermined corner among a plurality of corners of the cutting tool 10. The blade portion 12 is made of a cBN (cubic boron nitride) sintered body or a diamond sintered body (Polycrystalline diamond, PCD). The cBN sintered body is a sintered body containing cBN and a binder. The diamond sintered body is a sintered body containing diamond and a binder.

[0045] When the blade portion 12 is made of a cBN sintered body, the cBN content of the blade portion 12 is, for example, 40 volume % or more. As the binder, a binder having a composition consisting of at least one selected from the group consisting of nitrides, carbides, borides, oxides, and solid solutions of elements of Groups 4, 5, and 6 of the periodic table, and at least one selected from the group consisting of nitrides, borides, oxides, and solid solutions of aluminum can be used. When the cutting portion 12 is made of a diamond sintered body, the diamond content of the cutting portion 12 is, for example, 80 volume % or more.

[0046] The blade portion 12 is a polygonal plate-like shape, and in this embodiment, a triangular plate-like shape. As shown in Fig. 2, the blade portion 12 has a rake face 1, a flank face 2, a cutting edge 3 arranged on a ridge portion where the rake face 1 and the flank face 2 are connected, a chip breaker 4, and a protrusion 5. That is, the blade portion 12 has the rake face 1, the flank face 2, the cutting edge 3, the chip breaker 4, and the protrusion 5 arranged thereon. Therefore, the cutting tool 10 includes the rake face 1, the flank face 2, the cutting edge 3, the chip breaker 4, and the protrusion 5.

[0047] Fig. 3 shows a plan view (top view) of the cutting tool 10 near the cutting portion 12 as viewed from the insert axial direction. As shown in Fig. 3, the cutting edge 3 is V-shaped in plan view when the rake face 1 is viewed from the front. Specifically, the cutting edge 3 has a corner edge 3a that is convexly curved, and a pair of straight edges 3b that are connected to both ends of the corner edge 3a and extend straight. The chip breaker 4 is disposed on the inside of the rake face 1 as viewed from the plan.

[0048] [Direction definition] In this embodiment, an XYZ orthogonal coordinate system (three-dimensional orthogonal coordinate system) is appropriately set in each drawing, and each configuration will be described. In a plan view of the blade portion 12 (cutting tool 10) shown in FIG. 3, the direction in which the bisector B of the pair of straight blades 3b extends is referred to as the front-rear direction. The front-rear direction corresponds to the Y-axis direction in each drawing. In this embodiment, the bisector B is perpendicular to the insert central axis C. That is, the bisector B extends along a predetermined insert radial direction. Within the front-rear direction, the direction from the insert central axis C to the corner blade 3a is referred to as the front side (-Y side), and the direction from the corner blade 3a to the insert central axis C is referred to as the rear side (+Y side).

[0049] In addition, in a plan view of the cutting portion 12 (cutting tool 10) shown in Fig. 3, the direction perpendicular to the bisector B is referred to as the left-right direction. The left-right direction corresponds to the X-axis direction in each drawing. Of the left-right directions, when looking at the cutting face 1 from the front as shown in Fig. 3, the direction from the bisector B to the left is referred to as the left side (-X side), and the direction from the bisector B to the right is referred to as the right side (+X side). In addition, in the left-right direction, the direction approaching the bisector B is referred to as the inside (center side), and the direction away from the bisector B is referred to as the outside.

[0050] Moreover, the direction perpendicular to the front-rear direction and the left-right direction is called the up-down direction. The up-down direction corresponds to the Z-axis direction in each drawing. In the up-down direction, the direction in which the rake face 1 faces is called the upper side (+Z side), and the opposite direction is called the lower side (-Z side). In this embodiment, the up-down direction corresponds to the insert axial direction.

[0051] In this embodiment, the terms "front," "rear," "left side," "right side," "upper side," and "lower side" are simply names used to describe the relative positional relationships of each part, and the actual positional relationships, etc. when the tool is in use, etc. may be other than the positional relationships indicated by these names.

[0052] [Scooping surface] 2 and 3, the rake face 1 is disposed on one of a pair of plate faces (front and back faces) of the cutting portion 12 facing upward (front face). The rake face 1 is disposed adjacent to the cutting edge 3 on the inner side in the insert radial direction of the cutting edge 3. The rake face 1 has a land 15, a first rake face 16, and a second rake face 17.

[0053] The land 15 is a portion of the rake face 1 that is directly connected to the cutting edge 3. The land 15 extends along the cutting edge 3 and is generally V-shaped in the plan view shown in FIG. 3. In this embodiment, the land 15 is planar and extends in a direction perpendicular to the vertical direction. More specifically, as shown in FIGS. 4 to 7, the land 15 extends along the surface direction of a virtual plane (hereinafter referred to as a reference plane Pr) that is perpendicular to the vertical direction and passes through the cutting edge 3. For this reason, the rake angle of the land 15 is 0° in this embodiment. In this embodiment, the "rake angle" refers to an angle that represents the inclination of each portion of the rake face 1 with respect to the reference plane Pr.

[0054] As shown in Figs. 2 and 3, the first rake face 16 is a portion of the rake face 1 that is disposed inside the land 15. That is, the first rake face 16 is disposed farther away from the cutting edge 3 than the land 15 is. The first rake face 16 is connected to the land 15. The first rake face 16 extends along the cutting edge 3, and is generally V-shaped in the plan view shown in Fig. 3. In this embodiment, the front end of the first rake face 16 reaches the front end of the chip breaker 4 (specifically, the front end of a breaker wall surface 41 described later).

[0055] In this plan view, the first rake face 16 inclines downward in a direction perpendicular to the cutting edge 3 as it moves away from the cutting edge 3. For this reason, the rake angle of the first rake face 16 is a positive angle (positive angle).

[0056] The second rake face 17 is a portion of the rake face 1 that is disposed inside the first rake face 16. That is, the second rake face 17 is disposed farther from the cutting edge 3 than the first rake face 16. The second rake face 17 is connected to the first rake face 16. The second rake face 17 extends along the cutting edge 3, and is generally V-shaped in plan view as shown in FIG. 3. In this embodiment, the front end of the second rake face 17 is divided in the left-right direction by the front end of the chip breaker 4 (specifically, the front end of a breaker wall face 41, which will be described later).

[0057] In this plan view, the second rake face 17 inclines downward in a direction perpendicular to the cutting edge 3 as it moves away from the cutting edge 3. For this reason, the rake angle of the second rake face 17 is a positive angle (positive angle).

[0058] 5 to 7, the rake angle of the second rake face 17 is smaller than the rake angle of the first rake face 16. The difference (angle difference) between the rake angle of the first rake face 16 and the rake angle of the second rake face 17 is, for example, about 5°.

[0059] As shown in FIGS. 2 and 3, the rake face 1 has a corner rake face 18 and a pair of straight rake faces 19 connected to both ends of the corner rake face 18 .

[0060] The corner rake face 18 is a portion of the rake face 1 that is connected to the corner edge 3a. The corner rake face 18 is disposed at the front end of the rake face 1, and is curved to be convex toward the front side in the plan view shown in Fig. 3. The corner rake face 18 extends along the corner edge 3a.

[0061] The corner rake face 18 includes a convex curved portion located at the front end of the land 15, a convex curved portion located at the front end of the first rake face 16, and a convex curved portion located at the front end of the second rake face 17. In other words, the corner rake face 18 is composed of the convex curved portions located at the front ends of the land 15, the first rake face 16, and the second rake face 17.

[0062] The straight rake face 19 is the portion of the rake face 1 that is connected to the straight edge 3b. Of the pair of linear rake faces 19, one linear rake face 19 is disposed to the left (-X side) of the bisector B. The one linear rake face 19 is connected to one of the pair of linear blades 3b that is disposed to the left of the bisector B. The one linear rake face 19 extends along the one linear blade 3b. Specifically, the one linear rake face 19 extends linearly toward the left as it approaches the rear side in the plan view shown in FIG. 3.

[0063] One straight rake face 19 includes a straight portion of the land 15 located to the left of the bisector B, a straight portion of the first rake face 16 located to the left of the bisector B, and a straight portion of the second rake face 17 located to the left of the bisector B. In other words, one straight rake face 19 is composed of the straight portions of the land 15, the first rake face 16, and the second rake face 17 located to the left of the bisector B.

[0064] Of the pair of linear rake faces 19, the other linear rake face 19 is located to the right (+X side) of the bisector B. The other linear rake face 19 is connected to the other linear blade 3b of the pair of linear blades 3b that is located to the right of the bisector B. The other linear rake face 19 extends along the other linear blade 3b. Specifically, the other linear rake face 19 extends linearly toward the right as it moves toward the rear side in the plan view shown in FIG. 3.

[0065] The other straight rake face 19 includes a straight portion of the land 15 located to the right of the bisector B, a straight portion of the first rake face 16 located to the right of the bisector B, and a straight portion of the second rake face 17 located to the right of the bisector B. In other words, the other straight rake face 19 is composed of the straight portions of the land 15, the first rake face 16, and the second rake face 17 that are to the right of the bisector B.

[0066] [Flap surface] 2 and 4 to 7, the flank 2 is disposed on the outer circumferential surface of the cutting portion 12 at portions facing the front, left and right sides. The flank 2 is disposed below the cutting edge 3 and adjacent to the cutting edge 3. The flank 2 extends in the circumferential direction of the insert. In this embodiment, a clearance angle is imparted to the flank 2 over the entire circumferential direction of the insert.

[0067] The flank 2 has a corner flank 21 and a pair of linear flanks 22 connected to both ends of the corner flank 21 in the circumferential direction of the insert.

[0068] The corner flank 21 is a portion of the flank 2 that is connected to the corner edge 3a. The corner flank 21 is disposed at the front end of the flank 2 and has a curved shape that is convex toward the front side. The corner flank 21 inclines toward the inside in the insert radial direction as it moves downward from the corner edge 3a. In other words, a clearance angle is provided to the corner flank 21.

[0069] The straight flank 22 is a portion of the flank 2 that is connected to the straight edge 3b. Of the pair of linear flanks 22, one linear flank 22 is disposed on a portion of the flank 2 facing the left side (-X side). The one linear flank 22 is connected to one linear blade 3b of the pair of linear blades 3b that is located on the left side of the bisector B. The one linear flank 22 extends along the one linear blade 3b. The one linear flank 22 inclines toward the inside in the insert radial direction as it moves downward from the one linear blade 3b. The one linear flank 22 is an inclined flat surface. That is, a clearance angle is provided to the one linear flank 22.

[0070] Of the pair of linear flanks 22, the other linear flank 22 is disposed on a portion of the flank 2 facing the right side (+X side). The other linear flank 22 is connected to the other linear blade 3b of the pair of linear blades 3b that is located on the right side of the bisector B. The other linear flank 22 extends along the other linear blade 3b. The other linear flank 22 inclines toward the inside in the insert radial direction as it moves downward from the other linear blade 3b. The other linear flank 22 is an inclined flat surface. That is, a clearance angle is provided to the other linear flank 22.

[0071] [Cutting blade] 2 to 7, in this embodiment, the cutting edge 3 extends along a reference plane Pr perpendicular to the up-down direction. More specifically, the entire cutting edge 3 is included within the reference plane Pr. The cutting edge 3 has a corner edge 3a and a pair of straight edges 3b.

[0072] 2 and 3, the corner edge 3a has a curved shape that is convex toward the front side (-Y side), specifically, a convex arc shape. In this embodiment, the radius of curvature (nose R) of the corner edge 3a is, for example, about 0.4 mm. In this embodiment, the tool tip portion near the corner edge 3a may be referred to as the nose R or the vicinity of the nose R, etc.

[0073] The pair of straight blades 3b are smoothly connected without any steps to both ends of the corner blade 3a in the blade length direction. Specifically, each straight blade 3b extends along a tangent line that contacts both ends of the corner blade 3a.

[0074] Of the pair of straight blades 3b, one straight blade 3b is connected to one end (left end) of the corner blade 3a in the blade length direction. The straight blade 3b extends linearly from the connection with the corner blade 3a toward the rear side (+Y side) and then toward the left side (-X side).

[0075] Of the pair of straight blades 3b, the other straight blade 3b is connected to the other end (right end) of the corner blade 3a in the blade length direction. The other straight blade 3b extends linearly from the connection with the corner blade 3a toward the rear side (+Y side) and then toward the right side (+X side).

[0076] [Chip breaker] The chip breaker 4 is disposed inside the cutting edge 3 in the plan view shown in FIG. 3. The chip breaker 4 is disposed on the bisector B in this plan view and extends in the front-rear direction. The left-right dimension of the chip breaker 4 decreases toward the front side. The chip breaker 4 has a pointed shape that tapers toward the front side. In this embodiment, the chip breaker 4 has a substantially V-shape that extends following the shape of the V-shaped cutting edge 3.

[0077] The chip breaker 4 has a breaker wall surface 41 and a breaker bottom surface 42. The breaker wall surface 41 faces outward (toward the cutting edge 3) in the left-right direction. The breaker bottom surface 42 is disposed between the breaker wall surface 41 and the rake face 1.

[0078] In this embodiment, the blade portion 12 is formed symmetrically with respect to the bisector B. Therefore, a pair of breaker wall surfaces 41 are provided symmetrically with respect to the bisector B in a plan view. Also, a pair of breaker bottom surfaces 42 are provided symmetrically with respect to the bisector B in a plan view.

[0079] 2, in this embodiment, the vertical position of the upper end of the breaker wall surface 41 is the same as the vertical position of one plate surface (front surface) facing upward of the blade portion 12, and is also the same as the vertical position of the cutting edge 3. Therefore, the portion of the breaker wall surface 41 other than the upper end is located below the cutting edge 3.

[0080] As shown in FIGS. 2 and 3, the breaker wall surface 41 has a first wall surface 43, a second wall surface 44, a connecting wall surface 45, a first auxiliary wall surface 46, and a first step portion 47.

[0081] The first wall surface 43 is disposed at the front end of the breaker wall surface 41. The first wall surface 43 extends outward in the left-right direction toward the rear side. Specifically, of the pair of breaker wall surfaces 41, the first wall surface 43 of one of the pair of breaker wall surfaces 41 located on the left side of the bisector B extends toward the left toward the rear side. Also, of the pair of breaker wall surfaces 41, the first wall surface 43 of the other of the pair of breaker wall surfaces 41 located on the right side of the bisector B extends toward the right toward the rear side. Each first wall surface 43 is flat. The angle indicated by the symbol α1 in FIG. 3 represents a first opening angle α1 formed between the first wall surface 43 and the bisector B in this plan view.

[0082] 4 and 5, the first wall surface 43 is inclined outward in the left-right direction as it approaches the bottom. Specifically, the first wall surface 43 of one (left) breaker wall surface 41 is inclined toward the left as it approaches the bottom. Also, the first wall surface 43 of the other (right) breaker wall surface 41 is inclined toward the right as it approaches the bottom. The angle indicated by the symbol β1 in FIG. 5 represents a first inclination angle β1 at which the first wall surface 43 is inclined with respect to the up-down direction (Z-axis direction).

[0083] 2 and 3, the front end of each first wall surface 43 is connected to the corner rake face 18. In this embodiment, the front end of the first wall surface 43 is connected to the front end of the first rake face 16 located on the corner rake face 18 and the front end of the second rake face 17. That is, the front end of the first wall surface 43 is disposed on the corner rake face 18.

[0084] The chip breaker 4 further has a breaker ridge 48. The breaker ridge 48 is formed by connecting the upper edges of the first wall surfaces 43 of the pair of breaker wall surfaces 41. The breaker ridge 48 is located on the bisector B in the plan view shown in FIG. 3, that is, it extends in the front-rear direction along the bisector B.

[0085] More specifically, the breaker ridge 48 extends upward toward the rear side. The breaker ridge 48 is located below the cutting edge 3. By forming such a breaker ridge 48, as shown in Fig. 4, the cross-sectional shape of the front end portion of the chip breaker 4 (the shape of a cross section perpendicular to the bisector B) forms a V-shape (triangular shape) that is convex toward the upper side.

[0086] As shown in Figs. 2 and 3, the second wall surface 44 is disposed rearward of the first wall surface 43. The second wall surface 44 extends outward in the left-right direction toward the rear side. Specifically, of the pair of breaker wall surfaces 41, the second wall surface 44 of one of the pair of breaker wall surfaces 41 located on the left side of the bisector B extends toward the left toward the rear side. Also, of the pair of breaker wall surfaces 41, the second wall surface 44 of the other of the pair of breaker wall surfaces 41 located on the right side of the bisector B extends toward the right toward the rear side. Each second wall surface 44 is flat.

[0087] The angle indicated by the symbol α2 in FIG. 3 represents the second opening angle α2 formed between the second wall surface 44 and the bisector B in the plan view. The second opening angle α2 of the second wall surface 44 is larger than the first opening angle α1 of the first wall surface 43. Specifically, in this embodiment, the second opening angle α2 corresponds to 1 / 2 of the cutting edge rhombus angle (55° in plan view in this embodiment) of the cutting portion 12 of the rhombus insert (cutting tool 10) conforming to the ISO standard. Therefore, the second wall surface 44 extends parallel to the straight edge 3b. In this embodiment, the first opening angle α1 is set to be half or less of the second opening angle α2.

[0088] 7, the second wall surface 44 is inclined outward in the left-right direction as it approaches the bottom. Specifically, the second wall surface 44 of one (left) breaker wall surface 41 is inclined leftward as it approaches the bottom. Also, the second wall surface 44 of the other (right) breaker wall surface 41 is inclined rightward as it approaches the bottom.

[0089] 7 represents a second inclination angle β2 at which the second wall surface 44 is inclined with respect to the vertical direction (Z-axis direction). As shown in FIGS. 5 and 7, the first inclination angle β1 of the first wall surface 43 is greater than the second inclination angle β2 of the second wall surface 44.

[0090] As shown in Figs. 2 and 3, the connecting wall surface 45 is disposed between the first wall surface 43 and the second wall surface 44 in the front-rear direction. The connecting wall surface 45 is connected to the rear end of the first wall surface 43 and the front end of the second wall surface 44. The connecting wall surface 45 extends outward in the left-right direction toward the rear side. Specifically, the connecting wall surface 45 of one of the pair of breaker wall surfaces 41 located on the left side of the bisector B extends toward the left toward the rear side. In addition, the connecting wall surface 45 of the other of the pair of breaker wall surfaces 41 located on the right side of the bisector B extends toward the right toward the rear side.

[0091] The angle indicated by the symbol α3 in Fig. 3 represents the third opening angle α3 formed between the connecting wall surface 45 and the bisector B in the plan view. The third opening angle α3 is approximately equal to the first opening angle α1 at the front end of the connecting wall surface 45 connected to the first wall surface 43. The third opening angle α3 gradually increases from the front end of the connecting wall surface 45 toward the rear side. The third opening angle α3 is approximately equal to the second opening angle α2 at the rear end of the connecting wall surface 45 connected to the second wall surface 44.

[0092] 6, the connecting wall surface 45 is inclined outward in the left-right direction as it approaches the bottom. Specifically, the connecting wall surface 45 of one (left) breaker wall surface 41 is inclined leftward as it approaches the bottom. Also, the connecting wall surface 45 of the other (right) breaker wall surface 41 is inclined rightward as it approaches the bottom.

[0093] 6 indicates a third inclination angle β3 at which the connecting wall surface 45 is inclined with respect to the up-down direction (Z-axis direction). The third inclination angle β3 is approximately equal to the first inclination angle β1 at the front end of the connecting wall surface 45 connected to the first wall surface 43. The third inclination angle β3 gradually decreases from the front end of the connecting wall surface 45 toward the rear side. The third inclination angle β3 is approximately equal to the second inclination angle β2 at the rear end of the connecting wall surface 45 connected to the second wall surface 44. With the above-mentioned configuration, each connecting wall surface 45 has a twisted concave curved shape.

[0094] As shown in FIG. 2 and FIG. 3, the first auxiliary wall surface 46 is disposed rearward of the second wall surface 44. In this embodiment, the first auxiliary wall surface 46 is disposed at the rear end of the breaker wall surface 41. The first auxiliary wall surface 46 extends outward in the left-right direction toward the rear side. Specifically, the first auxiliary wall surface 46 of one of the pair of breaker wall surfaces 41 located on the left side of the bisector B extends toward the left toward the rear side. Also, the first auxiliary wall surface 46 of the other of the pair of breaker wall surfaces 41 located on the right side of the bisector B extends toward the right toward the rear side. Each of the first auxiliary wall surfaces 46 is flat.

[0095] The first auxiliary wall surface 46 extends parallel to the straight blade 3b. The distance between the first auxiliary wall surface 46 and the straight blade 3b is smaller than the distance between the second wall surface 44 and the straight blade 3b.

[0096] The first auxiliary wall surface 46 is inclined outward in the left-right direction as it approaches the bottom. Specifically, the first auxiliary wall surface 46 of one (left) breaker wall surface 41 is inclined toward the left as it approaches the bottom. Also, the first auxiliary wall surface 46 of the other (right) breaker wall surface 41 is inclined toward the right as it approaches the bottom.

[0097] The first step 47 is a wall surface facing the front side, and is connected to the rear end of the second wall surface 44 and the front end of the first auxiliary wall surface 46. Specifically, the first step 47 of one (left) breaker wall surface 41 is connected to the rear end of the one (left) second wall surface 44 and the front end of the one (left) first auxiliary wall surface 46. In addition, the first step 47 of the other (right) breaker wall surface 41 is connected to the rear end of the other (right) second wall surface 44 and the front end of the other (right) first auxiliary wall surface 46. Each of the first step portions 47 is inclined toward the front as it extends downward.

[0098] As shown in Figs. 2 to 7, the breaker bottom surface 42 is flat and extends in a direction perpendicular to the up-down direction. The breaker bottom surface 42 is disposed below the cutting edge 3 and the reference surface Pr, and more specifically, is located at the lowest position in the chip breaker 4. The breaker bottom surface 42 is disposed between the breaker wall surface 41 and the second rake face 17. A pair of breaker bottom surfaces 42 are provided on the left and right sides of the bisector B. Each breaker bottom surface 42 extends along the cutting edge 3, and more specifically, extends along each straight edge 3b.

[0099] As shown in Fig. 8, the breaker bottom surface 42 has a plurality of coolant grooves 42a extending on the breaker bottom surface 42. The plurality of coolant grooves 42a extend parallel to one another. Coolant is supplied to the coolant grooves 42a, for example, by external oil supply. Note that the coolant grooves 42a are not shown in the figures other than Fig. 8.

[0100] The multiple coolant grooves 42a extend in a direction intersecting the left-right direction (X-axis direction) in a plan view. In this embodiment, the multiple coolant grooves 42a extend along a part of the breaker wall surface 41 in a plan view, specifically, along the first wall surface 43. However, this is not limited thereto, and the multiple coolant grooves 42a may extend at an angle relative to the first wall surface 43 in a plan view. The extension direction of the coolant grooves 42a may be appropriately set according to, for example, the cutting angle during cutting. Preferably, the extension direction of the coolant grooves 42a is set to a direction intersecting the direction in which chips flow over the breaker bottom surface 42 during cutting.

[0101] The coolant grooves 42a are disposed in a portion of the breaker bottom surface 42 that is located at least in front of the first step portion 47. The coolant grooves 42a are formed, for example, by laser processing. The pitch (center-to-center distance) between adjacent coolant grooves 42a is, for example, about 30 μm. The groove depth of the coolant grooves 42a is, for example, about 10 μm. The cross-sectional shape of the coolant grooves 42a is, for example, V-shaped. The groove width of the coolant grooves 42a decreases toward the lower side.

[0102] 〔protrusion〕 2 and 3, the protrusions 5 are disposed on the rake face 1 and protrude from the rake face 1. At least a pair of the protrusions 5 are provided on the left and right sides of the bisector B in the plan view shown in FIG. 3. In this embodiment, one protrusion 5 is provided on the left and one on the right side of the bisector B. The front end of the chip breaker 4 is disposed between the pair of protrusions 5 provided on the left and right sides of the bisector B. Note that the protrusions 5 are not shown in FIG. 8.

[0103] Each protrusion 5 protrudes upward from the rake face 1 and has a rib shape extending in a predetermined direction. Each protrusion 5 is disposed on at least one of the corner rake face 18 and the front end of the straight rake face 19. In the plan view shown in Fig. 3, the protrusion 5 extends in a direction intersecting with the portion of the cutting edge 3 adjacent to the rake face 1 on which the protrusion 5 is disposed. That is, each protrusion 5 extends in a direction intersecting with the cutting edge 3 in the plan view.

[0104] Specifically, the protrusion 5 extends inward (toward the center) in the left-right direction as it approaches the rear side (+Y side). The direction in which the protrusion 5 extends (hereinafter may be referred to as the extending direction of the protrusion 5) is a direction that intersects with the bisector B in the plan view of Fig. 3. More specifically, the extending direction of the protrusion 5 in this plan view is perpendicular to the first wall surface 43 or the second wall surface 44, and in this embodiment, is perpendicular to the second wall surface 44.

[0105] In the following description, the direction approaching the bisector B along the extension direction of the protrusion 5 is referred to as the inside (center side) of the extension direction of the protrusion 5, and the direction away from the bisector B along the extension direction of the protrusion 5 is referred to as the outside of the extension direction of the protrusion 5.

[0106] The outer end of the projection 5 in the extension direction is connected to the land 15. The outer end of the projection 5 in the extension direction is formed flush with the land 15. The inner end of the projection 5 in the extension direction is disposed away from the chip breaker 4. Specifically, the inner end of the projection 5 in the extension direction is disposed away from at least the breaker wall surface 41 of the chip breaker 4. In this embodiment, the inner end of the projection 5 in the extension direction is located on the first rake face 16.

[0107] The protrusion 5 has a pair of protrusion side surfaces 51, 52 facing in a direction intersecting the extension direction of the protrusion 5 in the plan view shown in Fig. 3. The pair of protrusion side surfaces 51, 52 includes one protrusion side surface 51 and the other protrusion side surface 52. In this embodiment, the one protrusion side surface 51 faces the front side (-Y side), and the other protrusion side surface 52 faces the rear side (+Y side). The pair of protrusion side surfaces 51, 52 may face in a direction perpendicular to the extension direction of the protrusion 5.

[0108] As shown in FIGS. 2 and 3, one of the projection side surfaces 51 has a convex curved surface 51a and a connecting concave curved surface 51b that smoothly connects the convex curved surface 51a and the rake face 1. The convex curved surface 51a is disposed at the upper portion (top) of one of the projection side surfaces 51, and extends along the extension direction of the projection 5. The cross section of the convex curved surface 51a perpendicular to the extension direction forms a convex curved shape.

[0109] The connecting concave surface 51b is disposed on the lower portion of one of the protrusion side surfaces 51 and extends along the extension direction of the protrusion 5. The shape of a cross section perpendicular to the extension direction of the connecting concave surface 51b is a concave curve. The upper end of the connecting concave surface 51b is smoothly connected to the lower end of the convex surface 51a without any steps. The lower end of the connecting concave surface 51b is smoothly connected to the scooping face 1 without any steps, and specifically, in this embodiment, it is connected to the first scooping face 16.

[0110] The other protrusion side surface 52 has a concave curved surface 52a. The concave curved surface 52a extends along the extension direction of the protrusion 5. The cross section perpendicular to the extension direction of the concave curved surface 52a has a concave curved shape. The upper end of the concave curved surface 52a and the upper end of the convex curved surface 51a are connected to each other via the ridge of the protrusion 5. The lower end of the concave curved surface 52a is smoothly connected to the scooping face 1 without any step, and specifically, in this embodiment, it is connected to the first scooping face 16.

[0111] [Effects of this embodiment] In the cutting tool 10 of the present embodiment described above, the chip breaker 4 is disposed on the inside of the cutting face 1, and at least a pair of protrusions 5 is disposed on the cutting face 1. Specifically, each protrusion 5 is disposed on at least one of the corner rake face 18 and the front end portion of the straight rake face 19 of the rake face 1, and is located at the tip of the tool including the nose R.

[0112] When turning a workpiece using this cutting tool 10, at a large depth of cut, the chips are stably broken by contacting the chip breaker 4. Specifically, in this embodiment, "large depth of cut" means, for example, that the depth of cut ap is 0.5 mm or more.

[0113] On the other hand, when the depth of cut is small, the chips are unlikely to come into contact with the chip breaker 4 that extends on the bisector B in a plan view. Therefore, in this embodiment, when the depth of cut is small, the chips are made to come into contact with the protrusion 5 near the nose R. The chips are stably broken up by contacting the protrusion 5, or even if they are not broken up, they are curled into a regular spiral shape or the like, and are well disposed of. Specifically, in this embodiment, "a small depth of cut" means, for example, that the depth of cut ap is about 0.1 mm.

[0114] In this way, the cutting tool 10 of the present embodiment can prevent chips from easily stretching into irregular shapes at low depths of cut, and can stably prevent problems such as the chips becoming entangled in the chuck of a lathe (not shown). In other words, it is possible to stably improve chip disposability not only at high depths of cut, but also at low depths of cut.

[0115] As described later, for example, when the angle (cutting edge rhombus) formed between the pair of straight edges 3b in a plan view is large, or when the nose R (the radius of curvature of the corner edge 3a) is large, the distance between the cutting edge 3 and the chip breaker 4 tends to be large. In such a configuration, even if the cutting depth is not reduced, the chips may not easily come into contact with the chip breaker 4. On the other hand, according to this embodiment, even in the above configuration, the chips are brought into stable contact with the protrusions 5, and chip disposal is stably improved.

[0116] Moreover, of the pair of protrusion side surfaces 51, 52 provided on each protrusion 5, one is provided with a convex curved surface 51a, and the other is provided with a concave curved surface 52a. When the cutting conditions, etc. are set so that the chips come into contact with the convex curved surface 51a of the protrusion 5, the strength of the protrusion 5 is increased, so that damage to the protrusion 5 is suppressed. The effect of the protrusion 5 is stable over a long period of time. Furthermore, when the cutting conditions, etc. are set so that the chips come into contact with the concave curved surface 52a of the protrusion 5, it becomes easier to control the flow direction of the chips, and the chip discharge performance is improved.

[0117] In this embodiment, one protrusion side surface 51 faces the front side, and the other protrusion side surface 52 faces the rear side. In this case, during turning by pushing, which advances the nose R against the workpiece, chips are brought into contact with the convex curved surface 51a of one of the protrusion side surfaces 51. Generally, in turning, pushing is the main process, so that the strength of the protrusion 5 is increased and damage to the protrusion 5 is further suppressed.

[0118] In addition, during turning by drawing, in which the nose R is retracted relative to the workpiece, the chips are brought into contact with the concave curved surface 52a of the other protrusion side surface 52. This makes it possible to more stably improve chip disposal during drawing.

[0119] In this embodiment, one of the projection side surfaces 51 has a connecting concave curved surface 51b that smoothly connects the convex curved surface 51a and the rake face 1. In this case, the connecting concave curved surface 51b smoothly connects the convex curved surface 51a and the rake face 1. The connecting concave curved surface 51b further increases the strength of the protrusion 5. In addition, the connecting concave curved surface 51b makes it difficult for chips to get caught on the protrusion 5, and the chips are more stably guided toward the convex curved surface 51a.

[0120] In this embodiment, the outer end of the projection 5 along the extending direction is connected to the land 15 . In this case, the outer end of the projection 5 in the extending direction reaches the land 15 adjacent to the cutting edge 3. Therefore, even if the cutting depth during cutting is small, the chips are more likely to come into contact with the projection 5. The above-mentioned action and effect of the projection 5 are more stably achieved.

[0121] In this embodiment, the inner end of the projection 5 along the extending direction is disposed away from the chip breaker 4 . For example, in a configuration in which the inner end of the projection 5 in the extending direction is connected to the chip breaker 4, chip clogging may occur near the connecting portion between the projection 5 and the chip breaker 4. On the other hand, according to the above configuration of this embodiment, chips can pass between the inner end of the projection 5 in the extending direction and the chip breaker 4, so that the above-mentioned chip clogging can be suppressed.

[0122] In addition, in the plan view shown in FIG. 3, the extending direction of the projection 5 is perpendicular to the first wall surface 43 or the second wall surface 44 of the breaker wall surface 41 . In this case, the function of the protrusion 5 is stable and effective. If the position of the inner end of the protrusion 5 in the extension direction is the same, it is more preferable that the extension direction of the protrusion 5 is perpendicular to the second wall surface 44, as in this embodiment. If the extension direction of the protrusion 5 is perpendicular to the second wall surface 44, the outer end of the protrusion 5 in the extension direction is located further forward (nose R side), and the protrusion 5 is stably brought into contact with the chips at a small cutting depth.

[0123] In this embodiment, the front end of the chip breaker 4 is disposed between a pair of protrusions 5 provided on the left and right sides of the bisector B. In this case, by appropriately utilizing the pair of projections 5 arranged near the nose R and the front end of the chip breaker 4, it is possible to accommodate low cutting depth machining under various cutting conditions.

[0124] In this embodiment, the chip breaker 4 has a breaker wall surface 41 and a breaker bottom surface 42. Chips generated by the cutting edge 3 during cutting flow over the rake face 1 and are curled or cut by contacting the breaker bottom surface 42 and the breaker wall surface 41, and are suitably discharged from the tool.

[0125] Specifically, for example, when the cutting depth during cutting is relatively small, the chips are brought into contact with the first wall surface 43 located at the front side of the breaker wall surface 41. The first wall surface 43 has a small first opening angle α1 formed with the bisector B in a plan view, and a large space for receiving the chips is secured between the first wall surface 43 and the cutting edge 3. This prevents the chips from becoming clogged between the first wall surface 43 and the cutting edge 3.

[0126] Also, the first wall surface 43 has a large first inclination angle β1 with respect to the vertical direction. In other words, the first wall surface 43 has a small inclination angle (flat inclination) with respect to a virtual plane (e.g., reference plane Pr) perpendicular to the vertical direction. Therefore, thin chips that come into contact with the first wall surface 43 are broken up by the first wall surface 43 and stably flow out to the upper side of the first wall surface 43, and are discharged from above the tool.

[0127] Furthermore, for example, when the cutting depth during cutting is relatively large, the chips are brought into contact with the second wall surface 44 of the breaker wall surface 41, which is located rearward of the first wall surface 43. The second wall surface 44 has a large second opening angle α2 formed with the bisector B in a plan view. This makes it possible to dispose the second wall surface 44 approximately parallel to the cutting edge 3 (e.g., the straight edge 3b), and the chips generated by the cutting edge 3 during cutting are brought into contact with the second wall surface 44 approximately perpendicularly. This stably improves the chip disposal of thick chips.

[0128] In addition, the second wall surface 44 has a small second inclination angle β2 with respect to the vertical direction. In other words, the second wall surface 44 has a large inclination angle (is steeply inclined) with respect to a virtual plane (e.g., a reference plane Pr) perpendicular to the vertical direction. Therefore, thick chips that come into contact with the second wall surface 44 are stably curled and broken by the second wall surface 44.

[0129] As described above, according to this embodiment, even if the cutting depth is changed, the chip disposal performance is maintained good. In other words, the chip disposal performance can be stably improved under various cutting conditions.

[0130] In this embodiment, the second opening angle α2 corresponds to ½ of the cutting edge rhombus angle of the cutting portion 12 of the rhombus insert (cutting tool 10) conforming to the ISO standard in plan view. The second wall surface 44 extends parallel to the straight edge 3b in plan view. In this case, the chips flowing from the straight blade 3b toward the second wall surface 44 are brought into contact with the second wall surface 44 approximately perpendicularly, so that chip disposal is more stably improved, especially when the chips are thick.

[0131] In this embodiment, in plan view seen from the top-bottom direction as in Fig. 3, the third opening angle α3 formed between the connecting wall surface 45 and the bisector B gradually increases toward the rear side. Also, the connecting wall surface 45 is inclined outward in the left-right direction toward the bottom side, and the third inclination angle β3 at which the connecting wall surface 45 is inclined with respect to the top-bottom direction gradually decreases toward the rear side.

[0132] In this case, since the connecting wall surface 45 has a twisted concave curved shape, it is possible to smoothly connect the first wall surface 43 and the second wall surface 44 without any steps by this connecting wall surface 45. Since the first wall surface 43 and the second wall surface 44, which have different opening angles α1, α2 and inclination angles β1, β2, can be smoothly connected by the connecting wall surface 45, it is possible to suppress problems such as chips getting caught at the connecting parts between the wall surfaces 43-45 and the like, or the outflow direction becoming unstable.

[0133] In this embodiment, the front end of the first wall surface 43 of the chip breaker 4 is connected to the corner rake face 18, which increases the strength of the cutting edge near the corner edge 3a. The chipping resistance of the cutting edge 3 is improved. In addition, because the front end of the first wall surface 43 is located on the corner rake face 18, even during cutting with a relatively small cutting depth, the chips generated by the corner edge 3a are brought into stable contact with the first wall surface 43, which allows for good chip disposal.

[0134] In this embodiment, the first opening angle α1 is set to be half or less of the second opening angle α2. In this case, the first wall surface 43 extends significantly toward the front side, and the front end portion of the first wall surface 43 can be stably connected to the corner rake face 18. In addition, since the first wall surface 43 can be disposed at an appropriate distance from the cutting edge 3, a space is secured between the first wall surface 43 and the cutting edge 3, and chip disposal performance is stably improved.

[0135] In this embodiment, the breaker bottom surface 42 has a plurality of coolant grooves 42a, and the plurality of coolant grooves 42a extend in a direction intersecting the left-right direction in a plan view. During cutting using the cutting tool 10 of this embodiment, chips generated by the cutting blade 3 flow out, for example, toward the inside in the approximately left-right direction. If the multiple coolant grooves 42a provided on the breaker bottom surface 42 extend in a direction intersecting the left-right direction as in the above configuration, the coolant flowing through the coolant grooves 42a is less affected by the chips. This makes it easier to spread the coolant over a wide area (especially up to the front end) on the breaker bottom surface 42, and also makes it easier to ensure a large liquid film thickness. The lubricity of the coolant is increased, and cutting resistance is reduced. In addition, the occurrence of welding can also be suppressed.

[0136] In this embodiment, the plurality of coolant grooves 42a extend along the first wall surface 43 in a plan view. In this case, it is possible to effectively prevent the coolant flowing through the coolant groove 42a from being affected by chips flowing from the cutting edge 3 toward the first wall surface 43. In addition, in this case, the coolant groove 42a can be easily machined on the breaker bottom surface 42, making it easy to manufacture the tool.

[0137] In this embodiment, the coolant groove 42a is disposed at least in a portion of the breaker bottom surface 42 that is located forward of the first step portion 47. In this case, the coolant grooves 42a are arranged on the portion of the breaker bottom surface 42 that the chips will surely scrape against during cutting, so the coolant function can be obtained stably. Also, it is possible to prevent the strength of the tool from decreasing and the manufacturing process from becoming complicated, which would otherwise occur if the coolant grooves 42a were formed over an excessively wide area.

[0138] In this embodiment, the pitch (center-to-center distance) between adjacent coolant grooves 42a is, for example, about 30 μm. The groove depth of the coolant grooves 42a is, for example, about 10 μm. The cross-sectional shape of the coolant grooves 42a is, for example, V-shaped. That is, the groove width of the coolant grooves 42a becomes smaller toward the lower side. In this case, the desired shape of the coolant groove 42a can be stably given by laser processing, etc. In this embodiment, the spot diameter on the work surface (breaker bottom surface 42) during laser processing is, for example, about φ25 μm.

[0139] In this embodiment, the rake face 1 has a first rake face 16 and a second rake face 17, and the rake angle of the first rake face 16 is set larger than the rake angle of the second rake face 17. In this case, since the rake angle of the first rake face 16 close to the cutting edge 3 is made large, the chips generated from the cutting edge 3 can be stably guided toward the breaker bottom surface 42 and the breaker wall surface 41, thereby further improving chip disposal performance.

[0140] In this embodiment, a pair of breaker wall surfaces 41 are provided symmetrically with respect to the bisector B in a plan view, and the chip breaker 4 has a breaker ridge 48 formed by connecting the upper edges of the first wall surfaces 43 of the pair of breaker wall surfaces 41, and the breaker ridge 48 extends upward as it moves toward the rear side.

[0141] In this case, the height (vertical position) of the breaker ridge 48 increases toward the rear, and accordingly the height of the first wall surface 43 also increases toward the rear. As the cutting depth during cutting increases, the height of the first wall surface 43 with which the chips come into contact also increases, so chip disposal is stably improved.

[0142] As the height of the breaker ridge 48 decreases toward the front, the height of the first wall surface 43 also decreases toward the front. When the cutting depth is small, for example, it is possible to prevent chips from hitting the first wall surface 43 excessively, and to maintain good chip discharge performance.

[0143] In this embodiment, the cutting edge 12 on which the rake face 1, the flank 2, the cutting edge 3, the chip breaker 4 and the protrusions 5 are arranged is made of a cBN sintered body or a diamond sintered body. In this case, since the hardness of the blade portion 12 is increased, even when cutting a workpiece such as a hard and brittle material, wear and damage to the cutting edge 3, protrusion 5 and chip breaker 4 are suppressed, making it possible to perform stable cutting.

[0144] [Other configurations included in the present invention] The present invention is not limited to the above-described embodiment, and the configuration may be modified within the scope of the present invention, as described below. In the illustrations of the various modifications, the same components as those in the above-described embodiment are given the same reference numerals, and the following mainly describes the differences.

[0145] Fig. 9 is a top view showing a part (near the blade portion 12) of a cutting tool 20 according to a first modified example of the embodiment, with the coolant grooves 42a omitted. Fig. 10 is a top view showing a part (near the blade portion 12) of a cutting tool 30 according to a second modified example of the embodiment, with the coolant grooves 42a omitted.

[0146] 9 and 10 are diamond-shaped inserts having an outer shape conforming to the ISO standard, with the cutting edge rhombus angle (the angle between a pair of straight edges 3b) of the cutting portion 12 being 80° in plan view (top view). When the cutting edge rhombus angle is large like this, the distance between the cutting edge 3 and the chip breaker 4 tends to become large, but in the present invention, the protrusion 5 is provided near the nose R, so that good chip disposal is maintained even at a small depth of cut.

[0147] In the cutting tool 20 of the first modification, the extension direction of the protrusion 5 is perpendicular to the second wall surface 44 in the plan view shown in Fig. 9. In the cutting tool 30 of the second modification, the extension direction of the protrusion 5 is perpendicular to the first wall surface 43 in the plan view shown in Fig. 10.

[0148] FIG. 11 is a top view showing a part (near the blade portion 12) of a cutting tool 40 according to a third modified example of the above-described embodiment, and the coolant grooves 42a are not shown.

[0149] 11 is a diamond-shaped insert having an outer shape conforming to the ISO standard, with the cutting edge 12 having a diamond angle of 55° in plan view (top view). In this cutting tool 40, the curvature radius (nose R) of the corner edge 3a is, for example, about 0.2 mm.

[0150] 11, an angle γ2 formed between the extending direction of the projection 5, indicated by the symbol E, and the bisector B is smaller than an angle γ1 formed between a virtual straight line VL perpendicular to the second wall surface 44 and the bisector B. The difference between the angle γ1 and the angle γ2 (γ1-γ2) is, for example, about 33°.

[0151] According to the third modified example, it becomes easy to dispose the outer end of the projection 5 in the extending direction E further forward in the vicinity of the nose R. It is possible to more stably improve the chip discharge performance at a small cutting depth.

[0152] FIG. 12 is a top view showing a part (near the blade portion 12) of a cutting tool 50 according to a fourth modified example of the above-described embodiment, and the coolant grooves 42a are not shown.

[0153] The cutting tool 50 shown in Fig. 12 is a diamond-shaped insert having an outer shape conforming to the ISO standard, in which the cutting edge 12 has a diamond angle of 55° in plan view (top view). This cutting tool 50 has a corner edge 3a with a radius of curvature (nose R) of, for example, about 0.8 mm. When the nose R increases in this way, the distance between the cutting edge 3 and the chip breaker 4 tends to increase, but in the present invention, a protrusion 5 is provided near the nose R, so that good chip disposal is maintained even at a small depth of cut.

[0154] FIG. 13 is a top view showing a part (near the blade portion 12) of a cutting tool 60 according to a fifth modified example of the above-described embodiment, and the coolant grooves 42a are omitted.

[0155] 13 is a diamond-shaped insert having an outer shape conforming to the ISO standard, with the cutting edge 12 having a diamond angle of 55° in plan view (top view). In this cutting tool 60, the curvature radius (nose R) of the corner blade 3a is, for example, about 0.8 mm.

[0156] In the fifth modified example, the projection 5 is disposed across the first rake face 16 and the second rake face 17. The inner end of the projection 5 in the extending direction is connected to the breaker bottom surface 42. With this fifth modified example, the same effects as those of the above-mentioned embodiment can be obtained.

[0157] FIG. 14 is a top view showing a part (near the blade portion 12) of a cutting tool 70 according to a sixth modified example of the above-described embodiment, and the coolant grooves 42a are omitted.

[0158] In the sixth modified example, a plurality of protrusions 5 are provided side by side along the blade length direction in which the cutting edge 3 extends on the left or right side of the bisector B in the plan view shown in Fig. 14. In the illustrated example, two protrusions 5 (5A, 5B) are arranged side by side on the left side of the bisector B. In addition, two protrusions 5 (5A, 5B) are arranged side by side on the right side of the bisector B.

[0159] 14, the angle γ3 formed between the extension direction E of the projection 5A located on the front side and the bisector B is smaller than the angle γ1 formed between the virtual straight line VL perpendicular to the second wall surface 44 and the bisector B. Also, the angle γ4 formed between the extension direction E of the projection 5B located on the rear side and the bisector B is smaller than the angle γ1. Also, the angle γ3 is smaller than the angle γ4.

[0160] According to the sixth modification, it is possible to cope with low-depth cutting under various cutting conditions. The extension directions E of the multiple protrusions 5A, 5B may extend in different directions as shown in the figure, or may extend parallel to each other.

[0161] FIG. 15 is a top view showing a part (near the blade portion 12) of a cutting tool 80 according to a seventh modified example of the present embodiment, and the coolant grooves 42a are omitted.

[0162] In the seventh modification, one of the protrusion side surfaces 51 having the convex curved surface 51a and the connecting concave curved surface 51b faces the rear side (+Y side), and the other of the protrusion side surfaces 52 having the concave curved surface 52a faces the front side (-Y side). This seventh modification also provides the same effects as the above-described embodiment.

[0163] Although not specifically shown, in the above-described embodiment and each modified example, the inner end portion along the extending direction of the projection 5 may be connected to the breaker wall surface 41 of the chip breaker 4 .

[0164] In the above embodiment, the rake angle of the land 15 on the rake face 1 is 0°, but this is not limiting. The rake angle of the land 15 may be a negative angle or a positive angle. Furthermore, the land 15 does not have to be provided on the rake face 1.

[0165] 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]

[0166] INDUSTRIAL APPLICABILITY The cutting tool of the present invention can stably improve chip disposal performance at a small depth of cut, and therefore has industrial applicability. [Explanation of symbols]

[0167] 1…Scooping surface 2…Flank 3…Cutting edge 3a…Corner blade 3b…Straight blade 4…Chip breaker 5,5A,5B…Protrusion 10,20,30,40,50,60,70,80…Cutting tools 12...Blade part 15…Rand 18…Corner scooping face 19...Straight rake face 41…Breaker wall 42…Breaker bottom 42a…Coolant groove 43…First wall 44…Second wall 51...One side of the protrusion 52...other protrusion side 51a...Convex curved surface 51b…Connecting concave surface 52a…Concave surface B…Bisector E…Protrusion extension direction VL: Virtual line α1…First opening angle α2…Second opening angle γ1, γ2, γ3, γ4...Angle

Claims

1. The scooping surface and The relief surface and A cutting edge is disposed on a ridge portion where the rake face and the flank face are connected, and has a V-shape in a plan view of the rake face; a chip breaker disposed on an inner side of the rake face in the plan view; A protrusion is disposed on the rake face and protrudes from the rake face, The cutting blade is A corner blade having a convex curved shape; a pair of straight blades connected to both ends of the corner blade and each extending straight, A direction in which a bisector of the pair of straight blades extends in the plan view is defined as a front-rear direction, a direction perpendicular to the bisector in the plan view is defined as a left-right direction, and a direction perpendicular to the front-rear direction and the left-right direction is defined as a top-bottom direction. The rake face is a corner rake face connected to the corner edge; a pair of straight cutting faces connected to the pair of straight cutting edges; The chip breaker is disposed on the bisector in the plan view and extends in the front-rear direction, At least one pair of the projections is provided on the left and right sides of the bisector in the plan view, Each of the protrusions is disposed on at least one of the corner rake face and the front end of the straight rake face, and extends in a direction intersecting the cutting edge in the plan view; Of a pair of protrusion side surfaces facing a direction intersecting an extension direction of the protrusion in the plan view, one protrusion side surface has a convex curved surface, and the other protrusion side surface has a concave curved surface. cutting tools.

2. The one protrusion side surface faces the front side, The other protrusion side surface faces the rear side. The cutting tool according to claim 1.

3. The one protrusion side surface further has a connecting concave curved surface that smoothly connects the convex curved surface and the rake surface.

3. A cutting tool according to claim 1 or 2.

4. The rake face has a land that is connected to the cutting edge, extends along the cutting edge, and is V-shaped in the plan view, an outer end of the projection along the extending direction is connected to the land; 3. A cutting tool according to claim 1 or 2.

5. An inner end of the projection along the extension direction is disposed away from the chip breaker.

3. A cutting tool according to claim 1 or 2.

6. The chip breaker is A breaker wall surface facing outward in the left-right direction; a breaker bottom surface disposed between the breaker wall surface and the rake face; The breaker wall surface is a first wall surface extending outward in the left-right direction toward the rear; a second wall surface that is disposed rearward of the first wall surface and extends outward in the left-right direction toward the rear, In the plan view, a second opening angle formed between the second wall surface and the bisector is larger than a first opening angle formed between the first wall surface and the bisector, In the plan view, an extension direction of the protrusion is perpendicular to the first wall surface or the second wall surface.

3. A cutting tool according to claim 1 or 2.

7. The chip breaker is A breaker wall surface facing outward in the left-right direction; a breaker bottom surface disposed between the breaker wall surface and the rake face; The breaker wall surface is a first wall surface extending outward in the left-right direction toward the rear; a second wall surface that is disposed rearward of the first wall surface and extends outward in the left-right direction toward the rear, In the plan view, a second opening angle formed between the second wall surface and the bisector is larger than a first opening angle formed between the first wall surface and the bisector, In the plan view, an angle formed between an extension direction of the protrusion and the bisector is smaller than an angle formed between a virtual straight line perpendicular to the second wall surface and the bisector.

3. A cutting tool according to claim 1 or 2.

8. a front end of the chip breaker is disposed between a pair of the projections provided on the left and right sides of the bisector; 3. A cutting tool according to claim 1 or 2.

9. The protrusions are provided in a plurality of rows along the blade length direction in which the cutting edge extends, on the left or right side of the bisector in the plan view.

3. A cutting tool according to claim 1 or 2.

10. The chip breaker is A breaker wall surface facing outward in the left-right direction; a breaker bottom surface disposed between the breaker wall surface and the rake face; the breaker bottom surface has a plurality of coolant grooves extending thereon; The plurality of coolant grooves extend in a direction intersecting the left-right direction in the plan view.

3. A cutting tool according to claim 1 or 2.

11. a cutting edge portion on which the rake face, the flank face, the cutting edge, the chip breaker and the protrusion are disposed, The blade portion is made of a cBN sintered body or a diamond sintered body.

3. A cutting tool according to claim 1 or 2.

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