Cutting tools

Abstract

To provide a cutting tool which can excellently maintain chip disposal performance regardless of cutting amount or the like and stably enhance machining surface accuracy.SOLUTION: A cutting tool includes: a rake face 1; a flank 2; a cutting blade 3 which is arranged in a ridge line section to which the rake face 1 and the flank 2 are connected and forms into a V-shape in a plan view that the rake face 1 is viewed from a front direction; and a chip breaker 4 which is arranged in the rake face 1. The chip breaker 4 has a first projection section 41 which projects to an upper side from the rake face 1, a second projection section 42 which projects to the upper side from the rake face 1, is arranged on a rear side of the first projection section 41 and extends toward a front side as being separated from a bisector of the cutting blade 3 in a right and left direction, and a third projection section 43 which projects to the upper side from the rake face 1 and is arranged on a front side of the first projection section 41. The first projection section 41 and the second projection section 42 projects to an upper side than the cutting blade 3. The third projection section 43 is lower in a vertical direction than the first projection section 41.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Conventionally, cutting tools such as cutting inserts used when machining a workpiece such as metal are known (for example, Patent Documents 1 and 2). This type of cutting tool is disposed at a rake face, a flank face, and a ridge line portion where the rake face and the flank face are connected, and includes a cutting edge that forms a V shape in a plan view when the rake face is viewed from the front, and a chip breaker disposed on the rake face.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when the distance from the corner edge (nose R) located at the tip of the cutting edge to the chip breaker is long, chips are less likely to hit the chip breaker and are likely to elongate during low cutting with a small cutting amount, resulting in poor chip disposability. On the other hand, if the distance from the corner edge to the chip breaker is simply shortened, the chips are overly curled and hit the machined surface of the workpiece, reducing the machining surface accuracy.

[0005] One object of the present invention is to provide a cutting tool that can maintain good chip disposability regardless of the cutting amount and can stably improve the machining surface accuracy.

Means for Solving the Problems

[0006] [Aspect 1 of the present invention] The device comprises a rake face, a relief face, a cutting edge positioned on the ridge where the rake face and the relief face are connected, forming a V-shape in a plan view with the rake face facing forward, and a chip breaker positioned on the rake face, wherein in the plan view, the direction in which the bisector of the cutting edge extends is defined as the front-to-back direction, the direction perpendicular to the bisector is defined as the left-to-right direction, and the direction perpendicular to the front-to-back direction and the left-to-right direction is defined as the up-to-down direction, and the chip breaker is positioned such that A cutting tool having a first protrusion projecting upward from the rake face, a second protrusion projecting upward from the rake face and positioned behind the first protrusion, extending forward as it moves away from the bisector in the left-right direction, and a third protrusion projecting upward from the rake face and positioned in front of the first protrusion, wherein the first and second protrusions project upward above the cutting edge, and the third protrusion is shorter in the vertical direction than the first protrusion.

[0007] In the cutting tool of the present invention, for example, during high-depth cutting (high-feed) cutting, the chips generated by the cutting edge come into contact with the first and second protrusions of the chip breaker. That is, the chips are supported at two points by the two protrusions aligned in the front-to-back direction, and are compressed and curled by being sandwiched between these protrusions. As a result, thick chips can be stably curled, and good chip handling performance is maintained.

[0008] Specifically, the second protrusion extends forward as it moves away from the bisector in the left-right direction. Since the direction in which the second protrusion extends is approximately the same as the direction in which the chips generated by the cutting edge flow out on the rake face, the chips are guided in the flow direction by the second protrusion and are stably curled by the two protrusions. Therefore, chip handling performance is more stable.

[0009] Furthermore, when the depth of cut is small, such as at low cutting depths, the chips generated by the cutting edge come into contact with the third protrusion located on the front side of the chip breaker. This prevents the thin chips from stretching and ensures stable cutting.

[0010] Specifically, the third protrusion is shorter in the vertical direction than the first protrusion, meaning it protrudes less from the rake face. As a result, excessive curling of chips that come into contact with the third protrusion is suppressed, and chips are prevented from hitting the machined surface of the workpiece. This helps maintain good surface accuracy.

[0011] Based on the above, the present invention makes it possible to maintain good chip evacuation performance regardless of the depth of cut, and to stably improve the accuracy of the machined surface.

[0012] [Aspect 2 of the present invention] The cutting tool according to embodiment 1, wherein the second protrusion protrudes above the first protrusion.

[0013] In this case, the chips flowing out, supported at two points by the first and second protrusions, are spirally rolled and stably curled due to the difference in height between these protrusions. This further improves the stability of chip processing.

[0014] [Aspect 3 of the present invention] The cutting tool according to embodiment 1 or 2, wherein the chip breaker is positioned behind the second protrusion and has a breaker wall that protrudes above the second protrusion.

[0015] In this case, the chips that have overcome the second protrusion to the rear are stably processed by hitting the breaker wall.

[0016] [Aspect 4 of the present invention] The cutting edge comprises a corner blade having a convex curve shape and a pair of straight blades connected to both ends of the corner blade and each extending in a straight line, and the third convex portion is located below at least the corner blade of the cutting edge, according to any one of embodiments 1 to 3.

[0017] In this case, since the third protrusion is positioned below the corner cutting edge, excessive curling of chips generated by the corner cutting edge and in contact with the third protrusion is reliably suppressed, especially during low cutting depths. This reliably improves the accuracy of the machined surface.

[0018] 〔Aspect 5 of the present invention〕 The cutting tool according to aspect 4, wherein the third convex portion is located in front of the center of the radius of curvature of the corner edge in the plan view.

[0019] In this case, the chips generated by the corner edge during low cutting depth or the like are stably brought into contact with the third convex portion. The chip processing performance by the third convex portion can be more stably achieved.

[0020] 〔Aspect 6 of the present invention〕 The cutting tool according to aspect 4 or 5, wherein the first convex portion overlaps the center of the radius of curvature of the corner edge in the plan view.

[0021] In this case, during cutting, the vicinity of the boundary between the corner edge and the straight edge among the cutting edges, or the chips generated by the corner edge are stably brought into contact with the first convex portion. The chip processing performance by the first convex portion can be more stably achieved.

[0022] 〔Aspect 7 of the present invention〕 The cutting tool according to any one of aspects 1 to 6, wherein the angle formed between the ridge line of the second convex portion and the bisector in the plan view is 30° or more and 60° or less.

[0023] When the above angle is 30° or more and 60° or less, the chip processing performance by the second convex portion can be more stably achieved regardless of the opening angle of the cutting edge (the angle formed between a pair of straight edges) in the plan view or the tool posture during cutting. When the above angle is less than 30° or exceeds 60°, the chip outflow direction and the direction in which the second convex portion extends may greatly differ depending on the opening angle of the cutting edge or the tool posture during cutting, which may affect the chip disposability.

Advantages of the Invention

[0024] According to the cutting tool of the above aspect of the present invention, the chip disposability can be maintained well regardless of the cutting depth or the like, and the machining surface accuracy can be stably improved. [Brief explanation of the drawing]

[0025] [Figure 1] Figure 1 is a perspective view showing the cutting tool of this embodiment. [Figure 2] Figure 2 is a plan view (top view) of the cutting tool of this embodiment. [Figure 3] Figure 3 is a side view showing the cutting tool of this embodiment. [Figure 4] Figure 4 is a perspective view showing an enlarged view of section IV of Figure 1. [Figure 5] Figure 5 is a plan view (top view) showing a part of the cutting tool. [Figure 6] Figure 6 is a cross-sectional view showing the VI-VI section in Figure 5. [Figure 7] Figure 7 is a cross-sectional view showing the VII-VII section of Figure 5. [Figure 8] Figure 8 is a cross-sectional view showing the section VIII-VIII in Figure 5. [Figure 9] Figure 9 is a cross-sectional view showing the IX-IX section of Figure 5. [Figure 10] Figure 10 is a cross-sectional view showing the XX section of Figure 5. [Modes for carrying out the invention]

[0026] A cutting tool 10 according to one embodiment of the present invention will be described with reference to the drawings. The cutting tool 10 of this embodiment is a cutting insert used in an indexable cutting tool for turning (cutting) a workpiece such as metal. In this embodiment, the cutting tool 10 may be simply referred to as a tool or the like.

[0027] Although not specifically shown in the diagram, the indexable cutting tool comprises a holder and a cutting tool (cutting insert) 10. The holder is made of, for example, steel. The holder has a concave insert mounting seat located at the tip of the holder. The cutting tool 10 is made of, for example, cemented carbide. The cutting tool 10 is integrally formed from a single component. The cutting tool 10 is detachably attached to the insert mounting seat.

[0028] As shown in Figures 1 to 3, the cutting tool 10 is plate-shaped. In this embodiment, the cutting tool 10 is polygonal plate-shaped, specifically, a rectangular plate-shaped such as a rhombic plate-shaped one. More specifically, the cutting tool 10 in this embodiment has, for example, the external shape of a rhombic insert (cutting insert) conforming to a general ISO standard. However, it is not limited to this, and the cutting tool 10 may be polygonal plate-shaped such as a triangular plate-shaped, pentagonal plate-shaped, or hexagonal plate-shaped one.

[0029] The cutting tool 10 is a polygonal plate shape centered on the insert central axis C, and its pair of plate surfaces (front and back surfaces) face the direction in which the insert central axis C extends (insert axis direction). In this specification, the direction perpendicular to the insert central axis C is sometimes called the insert radial direction, and the direction that circles around the insert central axis C is sometimes called the insert circumferential direction. Of the insert radial directions, the direction approaching the insert central axis C is the inside of the insert radial direction, and the direction away from the insert central axis C is the outside of the insert radial direction.

[0030] In this embodiment, the cutting tool 10 has a shape that is inverted and symmetrical in the direction of the insert axis. That is, the cutting tool 10 is a so-called double-sided cutting insert. Furthermore, the cutting tool 10 has a shape that is 180° rotationally symmetrical with respect to the insert's central axis C.

[0031] The cutting tool 10 comprises a rake face 1, a relief face 2, a cutting edge 3 positioned on the ridge where the rake face 1 and the relief face 2 are connected, a chip breaker 4 positioned on the rake face 1, and a mounting hole 5.

[0032] The rake face 1 and the chip breaker 4 are positioned on at least one of the pair of polygonal plate faces of the cutting tool 10. More specifically, the rake face 1 and the chip breaker 4 are positioned at predetermined corners (acute corners in this embodiment) among a plurality of corners on one of the plate faces. The flank face 2 is positioned on the outer circumferential surface of the cutting tool 10. More specifically, the flank face 2 is positioned at predetermined corners (acute corners in this embodiment) on the outer circumferential surface of the cutting tool 10. The cutting edge 3 is positioned on the ridge where one of the plate faces and the outer circumferential surface of the cutting tool 10 are connected. More specifically, the cutting edge 3 is positioned at predetermined corners (acute corners in this embodiment) on the ridge of the cutting tool 10. The predetermined corners of the cutting tool 10 on which the rake face 1, flank face 2, cutting edge 3, and chip breaker 4 are located may be referred to as the "blade portion."

[0033] In this embodiment, the cutting tool 10 has a symmetrical shape with inverted front and back surfaces, and a 180° rotationally symmetric shape with respect to the insert's central axis C. Therefore, a total of four sets of rake face 1, flank face 2, cutting edge 3, and chip breaker 4 are provided on the two acute-angled corners on one side of the cutting tool 10 (front surface) and the two acute-angled corners on the other side of the cutting tool 10 (back surface). In addition, one mounting hole 5 is provided on the cutting tool 10.

[0034] Figure 2 shows a plan view (top view) of the cutting tool 10 as seen from the insert axis direction. Figure 5 shows a plan view (top view) of the vicinity of the cutting edge 3 (a predetermined corner and cutting edge) of the cutting tool 10 as seen from the insert axis direction. As shown in Figures 2 and 5, the cutting edge 3 has a V-shape when viewed from the front with the rake face 1 facing forward. Specifically, the cutting edge 3 has a convex curved corner edge 3a and a pair of straight edges 3b connected to both ends of the corner edge 3a, each extending in a straight line.

[0035] [Definition of direction] In this embodiment, an XYZ Cartesian coordinate system (3D Cartesian coordinate system) is appropriately set in each figure, and each configuration will be described. In the plan view of the cutting tool 10 shown in Figure 5, the direction in which the bisector B of the V-shaped cutting edge 3 extends is called the front-to-back direction. Specifically, the bisector B corresponds to the angle bisector of the central angle formed between the pair of straight cutting edges 3b in this plan view. The front-to-back direction corresponds to the Y-axis direction in each figure. 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. Of the front-to-back directions, the direction from the insert central axis C toward the corner cutting edge 3a is called the front side (-Y side), and the direction from the corner cutting edge 3a toward the insert central axis C is called the rear side (+Y side).

[0036] Furthermore, in the plan view of the cutting tool 10 shown in Figure 5, the direction perpendicular to the bisector B is called the left-right direction. The left-right direction corresponds to the X-axis direction in each figure. Of the left-right directions, as shown in Figure 5, when viewing the rake face 1 from the front, the direction to the left of the bisector B is called the left side (-X side), and the direction to the right of the bisector B is called the right side (+X side). Note that one of the left and right sides may be referred to as one side of the left-right direction, and the other as the other side of the left-right direction. Furthermore, the direction approaching the bisector B is called the inner (center) direction, and the direction moving away from the bisector B is called the outer direction.

[0037] Furthermore, the direction perpendicular to the front-back and left-right directions is called the up-down direction. In each figure, the up-down direction corresponds to the Z-axis direction. Of the up-down directions, 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 axis direction.

[0038] As shown in Figure 5, in this embodiment, a predetermined corner (blade portion) of the cutting tool 10 is formed in a symmetrical shape with respect to the bisector B as the axis of symmetry. In this embodiment, the terms front, rear, left, right, top, and bottom are merely names used to describe the relative positional relationship of each part, and the actual arrangement when using tools, etc., may be different from the arrangements indicated by these names.

[0039] [Scooping surface] As shown in Figures 4 and 5, the rake face 1 is positioned inside the cutting edge 3 on the plate surface of the cutting tool 10 facing the insert axis direction. Specifically, the rake face 1 is positioned adjacent to the cutting edge 3, on the inside in the insert radial direction of the cutting edge 3. The rake face 1 has a land 15 and an inclined surface 16.

[0040] The land 15 is the 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, in the plan view shown in Figure 5, forms a V-shape overall. As shown in the cross-sectional views (longitudinal cross-sectional views) of Figures 6 and 7, in this embodiment, the land 15 extends inclined downwards as it moves away from the cutting edge 3 along a virtual plane (hereinafter referred to as the reference plane Pr) that passes through the cutting edge 3 and is perpendicular to the vertical direction. That is, the land 15 has a positive angle (conformal angle) rake angle. In this embodiment, "rake angle" refers to the inclination angle of each part (each component) of the rake face 1 with respect to the reference plane Pr.

[0041] As shown in Figures 4 and 5, the inclined surface 16 is the portion of the rake face 1 located inside the land 15. That is, the inclined surface 16 is located further away from the cutting edge 3 than the land 15. The inclined surface 16 is connected to the land 15. The inclined surface 16 extends along the cutting edge 3 and, in the plan view shown in Figure 5, forms a roughly V-shape overall. In this plan view, the inclined surface 16 slopes downward as it moves away from the cutting edge 3 in a direction perpendicular to the cutting edge 3. For this reason, the rake angle of the inclined surface 16 is a positive angle (conformal angle). As shown in Figures 6 to 10, the rake angle of the inclined surface 16 is made larger on the conformal side than the rake angle of the land 15.

[0042] [Fleeing face] As shown in Figure 4, the flank surface 2 is positioned on the outer circumferential surface of the cutting tool 10, facing outward in the radial direction of the insert. Specifically, the flank surface 2 is positioned on the outer circumferential surface of the cutting tool 10, extending across the front, left, and right-facing portions at predetermined corners. The flank surface 2 extends in the circumferential direction of the insert. The flank surface 2 is positioned below the cutting edge 3, adjacent to the cutting edge 3.

[0043] In this embodiment, the cutting tool 10 is a double-sided type so-called negative insert, and the flank surface 2 is formed parallel to the insert's central axis C. That is, the flank angle of the flank surface 2 is set to 0°. In this embodiment, the "relief angle" refers to the angle of inclination of the relief surface 2 with respect to a virtual straight line (not shown) that passes through the cutting edge 3 and is perpendicular to the reference plane Pr, in a cross-sectional view perpendicular to the cutting edge 3, as shown in Figure 6.

[0044] As shown in Figures 4 and 5, the relief surface 2 has a corner relief surface 21 and a pair of straight relief surfaces 22 connected to both ends of the corner relief surface 21 in the insert circumferential direction.

[0045] The corner relief surface 21 is the portion of the relief surface 2 that is connected to the corner blade 3a. The corner relief surface 21 is located on the front side (-Y side) of the relief surface 2. Specifically, the corner relief surface 21 is located at the front end of the relief surface 2 and has a convex curved shape that protrudes forward.

[0046] The straight relief surface 22 is the portion of the relief surface 2 that is connected to the straight blade 3b. The straight relief surface 22 is planar in shape. Of the pair of straight relief surfaces 22, one straight relief surface 22 is positioned on the left side (-X side) of the relief surface 2. The one straight relief surface 22 is connected to one of the pair of straight blades 3b that is located to the left of the bisector B. The one straight relief surface 22 extends along the one straight blade 3b.

[0047] Of the pair of straight relief surfaces 22, the other straight relief surface 22 is positioned on the right side (+X side) of the relief surface 2. The other straight relief surface 22 is connected to the other straight blade 3b of the pair of straight blades 3b, which is located to the right of the bisector B. The other straight relief surface 22 extends along the other straight blade 3b.

[0048] [Cutting edge] As described above, the cutting edge 3 has a corner blade 3a and a pair of straight blades 3b. Of the cutting edges 3, the corner blade 3a has a curved shape that is convex toward the front side (-Y side), and specifically, it has a convex arc shape. In this embodiment, the corner blade 3a extends along the plane direction of the reference plane Pr which is perpendicular to the vertical direction. The entire corner blade 3a is contained within the plane of the reference plane Pr. However, it is not limited to this, and the corner blade 3a may be formed at an inclination with respect to the reference plane Pr.

[0049] A pair of straight blades 3b are connected to both ends of the corner blade 3a in the direction of its blade length. In the plan view shown in Figure 5, each straight blade 3b extends along the tangents that are in contact with both ends of the corner blade 3a.

[0050] 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 one straight blade 3b extends linearly to the left (-X side) as it moves from the connection point with the corner blade 3a toward the rear (+Y side). In this embodiment, the one straight blade 3b extends inclined downwards as it moves away from the connection point with the corner blade 3a along the blade length direction in which the one straight blade 3b extends.

[0051] 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 to the right (+X side) as it moves toward the rear (+Y side) from the connection point with the corner blade 3a. In this embodiment, the other straight blade 3b extends inclined downwards as it moves away from the connection point with the corner blade 3a along the blade length direction in which the other straight blade 3b extends.

[0052] [Chip breaker] As shown in Figures 4 and 5, the chip breaker 4 is positioned inside the cutting edge 3 on the plate surface of the cutting tool 10 facing the insert axis direction. At least a portion of the chip breaker 4 is positioned on the rake face 1. The chip breaker 4 has a first protrusion 41, a second protrusion 42, a third protrusion 43, and a breaker wall 44.

[0053] The first protrusion 41 projects upward from the scoop face 1. More specifically, the first protrusion 41 includes a portion of the scoop face 1 that is positioned on the inclined surface 16. The first protrusion 41 is formed in a projection shape so as to form part of a sphere. The surface (projection surface) of the first protrusion 41 is a convex curved surface, and more specifically, it is formed in a convex spherical shape so as to form part of a sphere.

[0054] In the plan view shown in Figure 5, the first protrusion 41 is located on the bisector B. In this plan view, the first protrusion 41 is positioned to coincide with the center O of the radius of curvature of the corner blade 3a. More specifically, in this embodiment, in this plan view, the apex 41a located at the upper end of the first protrusion 41 coincides with the center O of the radius of curvature of the corner blade 3a.

[0055] As shown in Figure 6, the top 41a of the first protrusion 41 is positioned above the reference plane Pr that extends in the vertical and perpendicular directions, passing through the uppermost corner blade 3a of the cutting edge 3. In other words, the first protrusion 41 protrudes above the cutting edge 3.

[0056] Furthermore, as shown in Figure 6, the front end of the first protrusion 41 is located below the corner blade 3a. Also, as shown in Figure 5 and Figure 7, which represents the VII-VII section of Figure 5, both ends of the first protrusion 41 in the left-right direction (the left end of the first protrusion 41 in Figure 7) are located below the corner blade 3a.

[0057] As shown in Figures 4 and 5, the second protrusion 42 projects upward from the rake face 1 and is positioned behind the first protrusion 41. More specifically, the second protrusion 42 includes a portion of the rake face 1 that is positioned on the inclined surface 16. The second protrusion 42 extends forward as it moves away from the bisector B in the left-right direction. The second protrusion 42 is formed in a rib shape. The surface of the second protrusion 42 has a convex curved shape.

[0058] The second protrusions 42 are provided in pairs, one on the left side (-X side) and the other on the right side (+X side) of the bisector B. The pair of second protrusions 42 are formed to be symmetrical with respect to the bisector B as the axis of symmetry. Therefore, the following description will mainly focus on one of the pair of second protrusions 42.

[0059] The inner (center) end of the second protrusion 42 in the left-right direction is located on the bisector B. In the plan view shown in Figure 5, the width of the inner portion of the second protrusion 42 in the left-right direction increases as it moves outward from the bisector B. Also in this plan view, the width of the outer portion of the second protrusion 42 in the left-right direction decreases as it moves outward.

[0060] Furthermore, in the plan view shown in Figure 5, the second protrusion 42 includes a portion located outside the center O of the radius of curvature of the corner blade 3a in the left-right direction (outer end in the left-right direction) and a portion located behind the center O (inner end in the left-right direction). The second protrusion 42 is positioned to surround the center O of the radius of curvature of the corner blade 3a and the first protrusion 41 from the left-right outer and rear sides.

[0061] In Figure 5, the sign L, indicated by a dashed line, represents the direction in which the ridge 42a of the second protrusion 42 extends. That is, the ridge 42a of the second protrusion 42 extends in a straight line. In the plan view shown in Figure 5, the angle α formed between the ridge 42a of the second protrusion 42 and the bisector B is, for example, between 30° and 60°.

[0062] As shown in Figure 4, the ridge line 42a of the second protrusion 42 extends upward as it moves from the outer end to the inner end in the left-right direction along the direction in which the ridge line 42a extends. In other words, as the second protrusion 42 approaches the bisector B along the direction in which its ridge line 42a extends, the amount of upward projection increases.

[0063] As shown in Figure 6, the second protrusion 42 has a portion located above the reference plane Pr that extends in the vertical and perpendicular directions, passing through the uppermost corner blade 3a of the cutting edge 3. In other words, the second protrusion 42 protrudes above the cutting edge 3.

[0064] As shown in Figures 6 and 7, the second protrusion 42 has a portion that is positioned above the uppermost apex 41a of the first protrusion 41. In other words, the second protrusion 42 protrudes above the first protrusion 41.

[0065] As shown in Figures 4 and 5, the third protrusion 43 protrudes upward from the scoop face 1 and is positioned in front of the first protrusion 41. More specifically, the third protrusion 43 is positioned on the inclined surface 16 of the scoop face 1. The third protrusion 43 is formed as a projection so as to form part of a sphere. The surface (projection surface) of the third protrusion 43 is a convex curved surface, and more specifically, it is formed as a convex spherical surface so as to form part of a sphere. In this embodiment, the radius of curvature of the projection surface (convex curved surface) of the third protrusion 43 is smaller than the radius of curvature of the projection surface (convex curved surface) of the first protrusion 41.

[0066] In the plan view shown in Figure 5, the third protrusion 43 is located on the bisector B. Also in this plan view, the third protrusion 43 is positioned in front of the center O of the radius of curvature of the corner blade 3a.

[0067] As shown in Figure 6, the entire third protrusion 43 is positioned below the reference plane Pr that extends vertically and perpendicularly through the corner blade 3a. In other words, the third protrusion 43 is located below at least the corner blade 3a of the cutting edge 3.

[0068] Furthermore, the uppermost apex 43a of the third protrusion 43 is located lower than the uppermost apex 41a of the first protrusion 41. In other words, the third protrusion 43 is shorter in height in the vertical direction than the first protrusion 41.

[0069] As shown in Figures 4 to 6, the breaker wall 44 is positioned behind the second protrusion 42 and protrudes above the second protrusion 42. The breaker wall 44 has a wall surface that is located above the second protrusion 42 and faces forward and to the left and right. In this embodiment, the breaker wall 44 has a conical surface portion 44a positioned adjacent to the rear of the second protrusion 42 and a wavy surface portion 44b positioned behind the conical surface portion 44a.

[0070] The conical surface portion 44a has a convex shape that is convex toward the front. The conical surface portion 44a has a convex curved shape that faces forward, to the left, and to the right, and extends in the circumferential direction of the insert. The conical surface portion 44a is formed so that its diameter decreases toward the upper side.

[0071] As shown in Figure 5, the corrugated surface portion 44b is connected to the left-right outer ends of the conical surface portion 44a and extends outward in the left-right direction as it approaches the rear. A pair of corrugated surface portions 44b are provided on the left side (-X side) and the right side (+X side) of the bisector B. The pair of corrugated surface portions 44b are formed in a symmetrical shape with respect to the bisector B as the axis of symmetry. Therefore, the following description will mainly focus on one of the pair of corrugated surface portions 44b.

[0072] The wavy surface portion 44b is formed in a wave-like shape, alternating between the inward (towards the center) and outward directions (like a meander) as it moves away from the connection point with the conical surface portion 44a along the direction in which the wavy surface portion 44b extends. Furthermore, the wavy surface portion 44b is inclined to approach the bisector B as it moves upward.

[0073] As shown in Figures 4 and 5, the chip breaker 4 further has a valley 45 located between the first protrusion 41 and the second protrusion 42. The valley 45 is located at the boundary between the first protrusion 41 and the second protrusion 42 and has a groove-like shape that is recessed on the lower side. As shown in Figure 5, the valley 45 extends forward as it moves away from the bisector B in the left-right direction. The direction in which the valley 45 extends is approximately the same as the direction in which the ridge 42a of the second protrusion 42 extends.

[0074] A pair of valleys 45 are provided, one on the left side (-X side) and the other on the right side (+X side) of the bisector B. The pair of valleys 45 are formed symmetrically with respect to the bisector B as the axis of symmetry. Therefore, the following description will mainly focus on one of the pair of valleys 45.

[0075] The inner (center) end of the valley 45 in the left-right direction is located on the bisector B. The outer end of the valley 45 in the left-right direction is connected to the inclined surface 16 of the rake face 1. As shown in Figures 6 to 8, the vertical position of the valley bottom (groove bottom) decreases as you move from the inner end to the outer end in the left-right direction along the direction in which the valley 45 extends.

[0076] More specifically, as shown in Figures 6 and 7, in the inner portion of the valley 45 in the left-right direction, the valley bottom of the valley 45 is located above the reference plane Pr that extends vertically and perpendicularly through the cutting edge 3. Also, as shown in Figure 8, in the outer portion of the valley 45 in the left-right direction (especially the outer end), the valley bottom of the valley 45 is located below the reference plane Pr (not shown) (i.e., below the cutting edge 3).

[0077] [Mounting holes] As shown in Figures 1 and 2, the mounting hole 5 penetrates the cutting tool 10 in the insert axial direction and opens into a pair of plate surfaces (front and back) of the cutting tool 10. The mounting hole 5 is a circular hole centered on the insert's central axis C. Although not specifically shown, clamp pieces, clamp screws, etc., for fixing the cutting tool 10 to the insert mounting seat of the holder are inserted into the mounting hole 5.

[0078] [Effects of this embodiment] In the cutting tool 10 of this embodiment described above, for example, when the depth of cut is large (high feed rate), the chips generated by the cutting edge 3 come into contact with the first protrusion 41 and the second protrusion 42 of the chip breaker 4. That is, the chips are supported at two points by the two protrusions 41 and 42 which are aligned in the front-to-back direction, and are compressed and curled by being sandwiched between these protrusions 41 and 42. As a result, thick chips can be stably curled, and good chip handling performance is maintained.

[0079] Specifically, the second protrusion 42 extends forward as it moves away from the bisector B in the left-right direction. Since the direction in which the second protrusion 42 extends is approximately the same as the direction in which the chips generated by the cutting edge 3 flow out on the rake face 1, the chips are guided in the flow direction by the second protrusion 42 and are stably curled by the two protrusions 41 and 42. Therefore, the chip processing performance is more stable.

[0080] Furthermore, when the depth of cut is small, such as at low cutting depths, the chips generated by the cutting edge 3 come into contact with the third protrusion 43 located on the front side of the chip breaker 4. This prevents the thin chips from stretching and ensures stable cutting.

[0081] Specifically, the third protrusion 43 is shorter in the vertical direction than the first protrusion 41, meaning that it protrudes less from the rake face 1. As a result, excessive curling of chips that come into contact with the third protrusion 43 is suppressed, and chips are prevented from hitting the machined surface of the workpiece. This helps to maintain good machined surface accuracy.

[0082] Based on the above, according to this embodiment, good chip evacuation performance can be maintained regardless of the depth of cut, and the accuracy of the machined surface can be stably improved.

[0083] In this embodiment, the second protrusion 42 protrudes above the first protrusion 41. In this case, the chips flowing out, supported at two points by the first protrusion 41 and the second protrusion 42, are spirally rolled and stably curled by the difference in height between these protrusions 41 and 42. This further improves the stability of chip processing.

[0084] In this embodiment, the chip breaker 4 is positioned behind the second protrusion 42 and has a breaker wall 44 that protrudes above the second protrusion 42. In this case, the chips that have overcome the second protrusion 42 to the rear are stably processed by contacting the breaker wall 44. In this embodiment, the chips that have overcome the second protrusion 42 are effectively processed by contacting the conical surface portion 44a.

[0085] In this embodiment, the third protrusion 43 is located below at least the corner blade 3a of the cutting edge 3. In this case, since the third protrusion 43 is positioned below the corner cutting edge 3a, excessive curling of the chips generated by the corner cutting edge 3a and in contact with the third protrusion 43 is reliably suppressed, especially during low cutting depths. This reliably improves the accuracy of the machined surface.

[0086] In this embodiment, the third protrusion 43 is located in front of the center O of the radius of curvature of the corner blade 3a in a plan view. In this case, chips generated by the corner cutting edge 3a, such as at low cutting depths, can be stably brought into contact with the third protrusion 43. The chip processing performance of the third protrusion 43 is more consistently effective.

[0087] In this embodiment, the first protrusion 41 coincides with the center O of the radius of curvature of the corner blade 3a in a plan view. In this case, during cutting, the chips near the boundary between the corner edge 3a and the straight edge 3b of the cutting edge 3, and the chips generated by the corner edge 3a, are stably brought into contact with the first protrusion 41. The chip processing performance of the first protrusion 41 is more stably achieved.

[0088] Furthermore, in this embodiment, in the plan view shown in Figure 5, the angle α formed between the ridge line 42a of the second protrusion 42 and the bisector B is 30° or more and 60° or less. When the angle α is between 30° and 60°, the chip removal performance of the second protrusion 42 is more stable and effective, regardless of the opening angle of the cutting edge 3 in a plan view (the angle formed between the pair of straight blades 3b) or the tool position during cutting. If the angle α is less than 30° or more than 60°, the direction of chip outflow and the direction in which the second protrusion 42 extends may differ significantly depending on the opening angle of the cutting edge 3 and the tool position during cutting, which may affect chip handling performance.

[0089] In this embodiment, in the outer portion of the valley 45 in the left-right direction (especially the outer end), the bottom of the valley 45 is located below the cutting edge 3. In this case, the depth of the valley 45 between the first and second protrusions 41 and 42 is significantly increased in the outer left-right portions of the protrusions 41 and 42 where the chip begins to make contact. As a result, the chip curling function with two-point support by the two protrusions 41 and 42 becomes more stable. Furthermore, even if wear progresses on the protrusions 41 and 42, the two-point support curling function is more easily maintained.

[0090] [Other components included in the present invention] It should be noted that the present invention is not limited to the embodiments described above, and modifications to the configuration, etc., are possible without departing from the spirit of the invention, as described below, for example.

[0091] In the embodiments described above, an example was given in which the rake angle of the land 15 on the rake face 1 is a positive angle (conformal angle), but this is not limited to this. The rake angle of the land 15 may be 0° or a negative angle (negative angle). Furthermore, the land 15 may not be provided on the rake face 1.

[0092] In the embodiment described above, an example was given in which the relief angle of the relief surface 2 is 0°, but this is not the only example. Although not specifically shown in the figures, the relief surface 2 may be inclined inward in the radial direction of the insert as it moves away from the cutting edge 3 in the insert axial direction. In this case, a predetermined relief angle is given to the relief surface 2.

[0093] In the embodiments described above, an example was given in which the cutting tool 10 is a double-sided type with a symmetrical shape that can be reversed front and back, but it is not limited to this. The cutting tool 10 may also be a single-sided type that does not have a symmetrical shape that can be reversed front and back.

[0094] In the embodiments described above, an example was given in which the cutting tool 10 is formed from a single component made of cemented carbide, but it is not limited to this. Although not specifically shown, the cutting tool 10 may include, for example, a base plate portion that is polygonal in shape and a cutting edge portion that is fixed in a recess located at the corner of the base plate portion. In this case, the base plate portion is made of, for example, cemented carbide, and the cutting edge portion is made of, for example, a cBN (cubic boron nitride) sintered body or a diamond sintered body (polycrystalline diamond, PCD). The cutting edge portion has a rake face 1, a relief face 2, a cutting edge 3, and a chip breaker 4. The base plate portion has a mounting hole 5.

[0095] In the embodiments described above, an example was given in which the cutting tool 10 is a cutting insert, but the invention is not limited to this. The cutting tool of the present invention only needs to have a rake face 1, a flank face 2, a cutting edge 3, and a chip breaker 4, and may be, for example, a replaceable head member of an indexable cutting tool. Alternatively, the cutting tool may be a solid type (integrated) cutting tool.

[0096] The present invention may be combined in any way that does not depart from the spirit of the invention, as described in the above embodiments and modifications, and the configurations may be added, omitted, substituted, or otherwise modified. Furthermore, the present invention is not limited by the above embodiments, but is limited only by the claims. [Industrial applicability]

[0097] The cutting tool of the present invention maintains good chip evacuation performance regardless of the depth of cut, and can stably improve the accuracy of the machined surface. Therefore, it has industrial applicability. [Explanation of Symbols]

[0098] 1... Scoop surface 2…Escape 3…Cutting edge 3a...Corner blade 3b…Straight blade 4…Chip breaker 10…Cutting tools 41...First protrusion 42...Second protrusion 42a(L)…Ridge line 43...Third protrusion 44... Breaker wall B…Bisector O...Center of the radius of curvature of the corner blade α…Angle

Claims

1. The scooping surface, The escape face, A cutting edge is positioned on the ridge where the rake face and the relief face are connected, and has a V-shape when viewed from above with the rake face facing forward. The rake face is provided with a chip breaker, In the aforementioned plan view, the direction in which the bisector of the cutting edge extends is defined as the front-to-back direction, the direction perpendicular to the bisector in the aforementioned plan view is defined as the left-to-right direction, and the direction perpendicular to the front-to-back direction and the left-to-right direction is defined as the up-and-down direction. The aforementioned chip breaker is A first protrusion projecting upward from the scooping surface, A second protrusion extends upward from the scoop surface, is positioned behind the first protrusion, and extends forward as it moves away from the bisector in the left-right direction, It has a third protrusion that protrudes upward from the scooping surface and is positioned in front of the first protrusion, The first and second protrusions protrude above the cutting edge, The third protrusion has a lower vertical height than the first protrusion. cutting tools.

2. The second protrusion protrudes upward from the first protrusion. The cutting tool according to claim 1.

3. The chip breaker is positioned behind the second protrusion and has a breaker wall that protrudes above the second protrusion. A cutting tool according to claim 1 or 2.

4. The aforementioned cutting edge is A corner blade with a convex curve shape, The corner blade is connected to both ends of the corner blade and has a pair of straight blades that extend in a straight line, The third protrusion is located at least below the corner cutting edge of the cutting edge. A cutting tool according to claim 1 or 2.

5. The third protrusion is located in front of the center of the radius of curvature of the corner blade in the plan view. The cutting tool according to claim 4.

6. The first protrusion coincides with the center of the radius of curvature of the corner blade in the plan view. The cutting tool according to claim 4.

7. In the aforementioned plan view, the angle formed between the ridge of the second protrusion and the bisector is 30° or more and 60° or less. A cutting tool according to claim 1 or 2.

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