Cutting insert

Abstract

The present invention provides a cutting insert that, even with a breaker in place, can be stably clamped and fixed from the thickness direction during manufacturing, suppresses damage to the insert, and enhances cutting performance during cutting. [Solution] A polygonal plate-shaped cutting insert 1, the upper surface 11 having a boss surface 24 arranged around a mounting hole 15, a breaker 25 recessed from the upper surface 11, and a land surface 26 extending at least along the long side 11a and the corner portion 11c and located outside the breaker 25, the boss surface 24 and the land surface 26 are located on the same virtual plane parallel to the lower surface, the land surface 26 has a long side land surface 26a and a corner land surface 26c, the land width of the long side land surface 26a is greater than or equal to the land width of the corner land surface 26c, and the corner land surface 26c has a land width reduction portion 26d along the corner portion 11c, where the land width decreases as it moves from the long side 11a towards the short side 11b.

Description

Technical Field

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

Background Art

[0002] Conventionally, as a replaceable rotary cutting tool such as a replaceable end mill, for example, a milling tool described in Patent Document 1 is known. The replaceable rotary cutting tool includes a holder that is rotated around a rotation axis, and a cutting insert that is detachably attached to an insert mounting seat of the holder. In this specification, the cutting insert may be simply referred to as an insert or the like. Also, the replaceable rotary cutting tool may be simply referred to as a cutting tool or a tool or the like.

[0003] The milling insert (cutting insert) disclosed in Patent Document 1 has a rectangular plate shape. This cutting insert includes a rectangular planar upper surface and a lower surface facing the thickness direction of the insert, side surfaces connected to the upper surface and the lower surface, a cutting edge disposed at a ridge line portion where the upper surface and the side surface are connected, and a mounting hole penetrating the insert in the thickness direction. Further, this cutting insert has a breaker recessed from the insert upper surface. By providing the breaker, the cutting performance can be enhanced and the chip disposal property can be improved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] During insert manufacturing, cutting inserts are sometimes fixed by clamping them from the thickness direction using a clamping jig, and a grinding wheel is applied to the outer circumference of the insert to form the cutting edge. In this case, if the cutting insert has a breaker, irregularities will occur on the top surface of the insert, making it difficult to stably fix the insert and ensure the accuracy of the cutting edge formation. In addition, when clamping and fixing the cutting insert, pressure is concentrated near the cutting edge located outside the breaker on the top surface of the insert, which may cause the insert to break. Furthermore, there was room for improvement in enhancing the cutting performance during machining with this type of breaker-equipped insert.

[0006] The present invention aims to provide a cutting insert that can be stably clamped and fixed from the thickness direction during manufacturing even when a breaker is provided, can suppress damage to the insert, and can further improve cutting performance during cutting. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides the following means.

[0008] [Aspect 1 of the present invention] A cutting insert having a polygonal plate shape, comprising: a polygonal upper and lower surface facing the thickness direction of the cutting insert; a side surface connected to the upper and lower surfaces; a cutting edge disposed on the ridge where the upper and side surfaces are connected; and a mounting hole penetrating the cutting insert in the thickness direction, wherein the upper surface has a short side disposed on the outer periphery of the upper surface; a long side disposed on the outer periphery of the upper surface and longer than the short side; and a corner portion disposed on the outer periphery of the upper surface and connected to the short side and the long side; the cutting edge has a main cutting edge disposed on the short side and a corner edge disposed on the corner portion; and the upper surface has a boss surface disposed around the mounting hole. A cutting insert comprising: a breaker positioned between the short side, the long side, and the corner portion and the boss surface, recessed from the upper surface; and a land surface extending at least along the long side and the corner portion and located outside the breaker, wherein the boss surface and the land surface are located on the same virtual plane parallel to the lower surface, and the land surface comprises a long side land surface extending along the long side and a corner land surface extending along the corner portion, the land width of the long side land surface being greater than or equal to the land width of the corner land surface, and the corner land surface having a land width reduction portion along the corner portion where the land width decreases as it moves from the long side towards the short side.

[0009] [Aspect 2 of the present invention] The cutting insert according to embodiment 1, wherein the land surface has a short-side land surface extending along the short side, and the land width of the short-side land surface is less than or equal to the land width of the corner land surface.

[0010] [Aspect 3 of the present invention] The cutting insert according to embodiment 1 or 2, wherein the upper surface extends along the short side and has a top portion located outside the breaker, the width of which the top portion is less than or equal to the land width of the corner land surface.

[0011] [Aspect 4 of the present invention] The cutting insert according to any one of embodiments 1 to 3, wherein the land surface does not have a short-side land surface extending along the short side.

[0012] [Aspect 5 of the present invention] The cutting insert according to any one of embodiments 1 to 4, wherein the upper surface has a honing that is connected to the cutting edge and extends along the cutting edge, and in a cross-sectional view perpendicular to the cutting edge, when the angle between the virtual plane and the honing is θ1 and the angle between the virtual plane and the breaker is θ2, the relationship θ1 > θ2 is satisfied. [Effects of the Invention]

[0013] According to the above-mentioned aspect of the present invention, a cutting insert is provided that can be stably clamped and fixed from the thickness direction during manufacturing even if a breaker is provided, can suppress damage to the insert, and can further improve cutting performance during cutting. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a plan view of the cutting insert according to this embodiment, viewed from the thickness direction. [Figure 2] Figure 2 is a side view of the cutting insert according to this embodiment, viewed from the left and right directions. [Figure 3] Figure 3 is a front view (rear view) of the cutting insert according to this embodiment, viewed from the front-rear direction. [Figure 4] Figure 4 is a cross-sectional view showing the IV-IV section of Figure 1, specifically representing the section perpendicular to the outer cutting edge. [Figure 5] Figure 5 is a cross-sectional view showing the VV section of Figure 1, specifically representing a section perpendicular to the corner cutting edge. [Figure 6] Figure 6 is a cross-sectional view showing the VI-VI section of Figure 1, specifically representing a section perpendicular to the main cutting edge. [Figure 7] Figure 7 is a cross-sectional view showing the VII-VII section of Figure 1, specifically representing a section perpendicular to the wiper blade. [Figure 8] Figure 8 is a perspective view showing the holder according to this embodiment. [Figure 9]FIG. 9 is a perspective view showing a cutting tool with replaceable cutting edges according to the present embodiment. [Figure 10] FIG. 10 is a side view showing a cutting tool with replaceable cutting edges according to the present embodiment. [Figure 11] FIG. 11 is a plan view of a cutting insert according to a modified example of the present embodiment as viewed in the thickness direction. [Figure 12] FIG. 12 is a side view of a cutting insert according to a modified example of the present embodiment as viewed in the left-right direction. [Figure 13] FIG. 13 is a front view (rear view) of a cutting insert according to a modified example of the present embodiment as viewed in the front-rear direction. [Figure 14] FIG. 14 is a cross-sectional view showing the XIV-XIV cross-section of FIG. 11, specifically representing a cross-section perpendicular to the outer peripheral cutting edge. [Figure 15] FIG. 15 is a cross-sectional view showing the XV-XV cross-section of FIG. 11, specifically representing a cross-section perpendicular to the corner cutting edge. [Figure 16] FIG. 16 is a cross-sectional view showing the XVI-XVI cross-section of FIG. 11, specifically representing a cross-section perpendicular to the main cutting edge. [Figure 17] FIG. 17 is a cross-sectional view showing the XVII-XVII cross-section of FIG. 11, specifically representing a cross-section perpendicular to the wiper cutting edge.

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] <统一编号 The cutting insert 1 and the cutting tool with replaceable cutting edges 30 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 10. The cutting tool with replaceable cutting edges 30 of the present embodiment is a milling tool such as a replaceable end mill or a replaceable cutter for performing milling on a workpiece such as a metal material. <统一编号 <统一编号

[0016] <统一编号 As shown in Figures 1 to 3, the cutting insert 1 has a polygonal plate shape centered on the central axis C. Specifically, the cutting insert 1 in this embodiment has a rectangular plate shape, or more precisely, a rectangular plate shape or a parallelogram plate shape. Also, as shown in Figures 9 and 10, the replaceable tip rotary cutting tool 30 has a roughly cylindrical shape centered on the rotation axis J.

[0017] The replaceable-tip rotary cutting tool 30 comprises a holder 31 that can be rotated around a rotation axis J, a cutting insert 1 that is detachably attached to an insert mounting seat 33 of the holder 31, and a fastening member 38 that fixes the cutting insert 1 to the insert mounting seat 33. Multiple cutting inserts 1 and fastening members 38 are provided on the replaceable-tip rotary cutting tool 30. In this embodiment, three cutting inserts 1 are provided on the replaceable-tip rotary cutting tool 30. However, the number of cutting inserts 1 is not limited to three; it may be two or fewer, or four or more.

[0018] In this embodiment, an XYZ Cartesian coordinate system (3D Cartesian coordinate system) is appropriately set in each of Figures 1 to 3, and the components of the cutting insert 1 will be described.

[0019] In this embodiment, the direction in which the central axis C of the cutting insert 1 extends is called the thickness direction. In Figures 1 to 3, the thickness direction corresponds to the Z-axis direction. The cutting insert 1 has an upper surface 11 and a lower surface 12 that face opposite each other in the thickness direction. In the thickness direction, the direction in which the upper surface 11 faces is called the upper side (+Z side), and the direction in which the lower surface 12 faces is called the lower side (-Z side). Note that the thickness direction (Z-axis direction) is the direction in which the central axis C of the cutting insert 1 extends, so it can also be referred to as the axis direction. In this case, the upper side corresponds to one side of the axis direction, and the lower side corresponds to the other side of the axis direction. The thickness direction can also be referred to as the up and down direction.

[0020] In each figure, the Y-axis direction is the front-to-back direction, perpendicular to the thickness direction (Z-axis direction). In this embodiment, the -Y side of the front-to-back direction (Y-axis direction) is called the front side, and the +Y side is called the rear side.

[0021] Furthermore, the X-axis direction is the left-right direction, which is perpendicular to the thickness direction (Z-axis direction) and the front-to-back direction (Y-axis direction). In this embodiment, the -X side of the left-right direction (X-axis direction) is called the left side, and the +X side is called the right side. Also, the direction approaching the central axis C along the left-right direction is called the center side of the left-right direction or the inside of the left-right direction. The direction moving away from the central axis C along the left-right direction is called the outside of the left-right direction.

[0022] Furthermore, the direction perpendicular to the central axis C is called the radial direction. Within the radial direction, the direction approaching the central axis C is called the radially inward direction, and the direction moving away from the central axis C is called the radially outward direction. Furthermore, the direction in which something revolves around the central axis C is called the circumferential direction.

[0023] In Figures 8 to 10, the direction in which the rotation axis J, which is the central axis of the replaceable-tip rotary cutting tool 30 and the holder 31, extends is called the tool axis direction. The insert mounting seat 33 is located at one end of the holder 31 in the tool axis direction. Of the two ends of the holder 31 in the tool axis direction, the direction from the end where the insert mounting seat 33 is located to the other end is called the rear end side, and the direction from the other end to the first end is called the front end side. Note that the rotation axis J may also be referred to as the tool central axis J.

[0024] Furthermore, the direction perpendicular to the axis of rotation J is called the tool radial direction. Within the tool radial direction, the direction approaching the axis of rotation J is called the inner side of the tool radial direction, and the direction moving away from the axis of rotation J is called the outer side of the tool radial direction.

[0025] Furthermore, the direction of rotation around the rotation axis J is called the tool circumferential direction. Of the tool circumferential directions, the direction in which the replaceable-tip rotary cutting tool 30 is rotated by the spindle of the machine tool during cutting is called the tool rotation direction TD, and the rotation direction opposite to this is called the opposite side of the tool rotation direction TD or the anti-tool rotation direction.

[0026] Here, the central axis C of the cutting insert 1 may be referred to as the insert central axis C to clearly distinguish it from the tool central axis J. Also, the radial direction of the cutting insert 1 may be referred to as the insert radial direction to clearly distinguish it from the tool radial direction. Furthermore, the circumferential direction of the cutting insert 1 may be referred to as the insert circumferential direction to clearly distinguish it from the tool circumferential direction.

[0027] The cutting insert 1 is formed from a hard sintered body, such as cemented carbide. As shown in Figures 1 to 3, the cutting insert 1 of this embodiment has a shape that is 180° rotationally symmetrical around the central axis C. Furthermore, the cutting insert 1 does not have a front-to-back (up-down) inversion symmetrical shape. The cutting insert 1 of this embodiment is a so-called single-sided type positive insert.

[0028] The cutting insert 1 comprises an upper surface 11 facing upward (+Z side) in the thickness direction of the cutting insert 1, a lower surface 12 facing downward (-Z side) in the thickness direction, a side surface 13 extending circumferentially outward in the radial direction and connected to the upper surface 11 and the lower surface 12, a cutting edge 14 positioned on the ridge where the upper surface 11 and the side surface 13 are connected, and a mounting hole 15 penetrating the cutting insert 1 in the thickness direction.

[0029] The top surface 11 has a polygonal shape. Specifically, the top surface 11 has a quadrilateral shape, or more precisely, a rectangular or parallelogram shape. The top surface 11 can also be referred to as a rake face.

[0030] As shown in Figure 1, the dimension of the top surface 11 in the front-to-back direction (Y-axis direction) is larger than the dimension in the left-to-right direction (X-axis direction). That is, the longitudinal direction of the top surface 11 corresponds to the front-to-back direction, and the transverse direction corresponds to the left-to-right direction.

[0031] The four sides arranged on the outer periphery of the top surface 11 include a pair of long sides 11a extending in the front-to-back direction and a pair of short sides 11b extending in a direction intersecting the long sides 11a. In addition, four corner portions 11c are arranged at the four corners of the outer periphery of the top surface 11, positioned between the long sides 11a and the short sides 11b and connecting the long sides 11a and the short sides 11b. That is, the top surface 11 has short sides 11b arranged on the outer periphery of the top surface 11, long sides 11a arranged on the outer periphery of the top surface 11 that are longer than the short sides 11b, and corner portions 11c arranged on the outer periphery of the top surface 11 that connect the short sides 11b and the long sides 11a. Other components of the upper surface 11 will be described separately.

[0032] The lower surface 12 has a polygonal shape. Specifically, the lower surface 12 has a quadrilateral shape, or more precisely, a rectangular or parallelogram shape. The lower surface 12 can also be referred to as the seating surface.

[0033] As shown in Figures 2 and 3, the dimension of the lower surface 12 in the front-to-back direction (Y-axis direction) is larger than the dimension in the left-to-right direction (X-axis direction). That is, the longitudinal direction of the lower surface 12 corresponds to the front-to-back direction, and the transverse direction corresponds to the left-to-right direction.

[0034] The lower surface 12 is planar and perpendicular to the central axis C. The lower surface 12 is considered to be a plane extending parallel to the XY plane. The surface area of ​​the lower surface 12 is smaller than the surface area of ​​the upper surface 11. Although not specifically shown in the figures, when the upper surface 11 and the lower surface 12 are projected in the thickness direction (Z-axis direction) onto a virtual plane perpendicular to the central axis C, the lower surface 12 projected onto the virtual plane is contained within the outer periphery of the upper surface 11 projected onto the virtual plane.

[0035] The side surface 13 is an annular shape extending around the central axis C. The upper end of the side surface 13 in the thickness direction is connected to the outer circumference of the upper surface 11. The lower end of the side surface 13 in the thickness direction is connected to the outer circumference of the lower surface 12. The side surface 13 may also be referred to as a relief surface.

[0036] The side surface 13 has a pair of side walls 16 facing in the front-to-back direction and a pair of side walls 17 facing in the left-to-right direction. The pair of side walls 16 have a front side wall 16a facing the front side (-Y side) and a rear side wall 16b facing the rear side (+Y side). The front side wall 16a extends towards the rear as it is directed downward in the thickness direction (-Z side). The rear side wall 16b extends towards the front as it is directed downward in the thickness direction.

[0037] The pair of side walls 17 have a left wall 17a facing left (-X side) and a right wall 17b facing right (+X side). The left wall 17a extends to the right as it is directed downward in the thickness direction. The right wall 17b extends to the left as it is directed downward in the thickness direction.

[0038] In other words, the side surface 13 extends radially inward as it moves downward in the thickness direction. This makes it easy to create a relief angle between the machined surface of the workpiece and the side surface (relief surface) 13 during machining, and increases the design flexibility of the mounting position of the cutting insert 1 to the insert mounting seat 33.

[0039] As shown in Figure 1, the cutting edge 14 is positioned along the long side 11a, corner portion 11c, and short side 11b of the outer circumference of the upper surface 11, forming a roughly L-shape in plan view from the thickness direction. Furthermore, the cutting edge 14 is located on a virtual plane perpendicular to the central axis C. That is, the cutting edge 14 extends on a virtual plane parallel to the XY plane. For this reason, each part (each component) of the cutting edge 14, as described later, is linear when viewed from the radial direction perpendicular to the central axis C.

[0040] Multiple cutting edges 14 are provided on the cutting insert 1. In this embodiment, the cutting insert 1 is a single-sided positive insert having a shape that is 180° rotationally symmetric with respect to the central axis C, and two cutting edges 14 are provided at positions that are 180° rotationally symmetric to each other with respect to the central axis C. The two cutting edges 14 have a common configuration. Below, one of the two cutting edges 14 will be described. Note that when this cutting insert 1 is mounted on the insert mounting seat 33, one of the two cutting edges 14 protrudes toward the tip side of the tip surface of the holder 31 and protrudes outward in the tool radial direction from the outer peripheral surface of the holder 31.

[0041] The cutting edge 14 includes an outer peripheral blade 18, a corner blade 19, a main cutting edge 20, a wiper blade 21, a convex curved blade 22, and an inner peripheral corner blade 23.

[0042] The outer cutting edge 18 is positioned on the long side 11a. As shown in Figure 1, in a plan view of the cutting insert 1 from the thickness direction (insert plan view), the outer cutting edge 18 is in a straight line extending along the front-to-back direction (Y-axis direction).

[0043] The corner blade 19 is positioned at the corner portion 11c. The corner blade 19 is positioned adjacent to the outer peripheral blade 18 on the front side (-Y side) of the outer peripheral blade 18. In the insert plan view of Figure 1, the corner blade 19 has a curved shape that is convex toward the front and outward in the left-right direction (specifically, to the right (+X side)). The rear end of the corner blade 19 is connected so as to be in contact with the front end of the outer peripheral blade 18. That is, the corner blade 19 and the outer peripheral blade 18 are smoothly connected so that they have a common tangent at their connection point. The corner blade 19 curves inward in the left-right direction (specifically, to the left (-X side)) as it extends toward the front from the connection point with the outer peripheral blade 18.

[0044] In this embodiment, the corner blade 19 has a composite convex arc shape consisting of multiple convex arcs with different radii of curvature. Specifically, the corner blade 19 has a first corner blade portion 19a and a second corner blade portion 19b connected to the first corner blade portion 19a, which has a different radius of curvature from the first corner blade portion 19a when viewed from above the insert.

[0045] The first corner cutting edge portion 19a is positioned on the rear portion of the corner cutting edge 19. The rear end of the first corner cutting edge portion 19a is connected to the front end of the outer peripheral cutting edge 18. In a plan view of the insert, the first corner cutting edge portion 19a has a convex arc shape with a predetermined radius of curvature.

[0046] The second corner cutting edge portion 19b is positioned on the front portion of the corner cutting edge 19. In a plan view of the insert, the second corner cutting edge portion 19b has a convex arc shape with a radius of curvature smaller than that of the first corner cutting edge portion 19a. The overall length (blade length) of the second corner cutting edge portion 19b is smaller than that of the first corner cutting edge portion 19a.

[0047] The outer end (right end) and rear end of the second corner blade portion 19b in the left-right direction are connected to the inner end (left end) and front end of the first corner blade portion 19a in the left-right direction. In other words, the first corner blade portion 19a and the second corner blade portion 19b are smoothly connected such that they have a common tangent at their connection point.

[0048] The main cutting edge 20 is positioned on the short side 11b. The main cutting edge 20 is positioned adjacent to the corner cutting edge 19 on the inside in the left-right direction (specifically, on the left side (-X side)). The main cutting edge 20 has the longest blade length among all the components (each cutting edge 18-23) of the cutting edge 14. In a plan view of the insert, the main cutting edge 20 extends linearly toward the front (-Y side) as it moves away from the corner cutting edge 19 in the left-right direction (towards the left). That is, the main cutting edge 20 extends in a direction that is inclined with respect to the left-right direction.

[0049] In this specification, the term "straight" for a cutting edge includes not only perfectly straight edges but also substantially straight edges within a certain margin of error. For example, in the case of a cutting insert 1 with a main cutting edge 20 length of, for example, about 3 mm, a gently curving arc shape with a radius of curvature exceeding 50 mm in a plan view of the insert, or a curved shape that meanders with a meander width of 0.05 mm or less, are also included in the definition of "straight" in this specification.

[0050] The rightmost and rearmost ends of the main cutting edge 20 are connected to the leftmost and frontmost ends of the second corner cutting edge 19b. In other words, the main cutting edge 20 and the second corner cutting edge 19b (corner cutting edge 19) are smoothly connected such that they share a common tangent at their connection point.

[0051] The wiper blade 21 is positioned on the short side 11b. The wiper blade 21 is positioned on the opposite side of the main cutting edge 20 from the corner blade 19 in the left-right direction (specifically, on the left side (-X side) of the main cutting edge 20). In a plan view of the insert, the wiper blade 21 extends approximately along the left-right direction. More specifically, as the wiper blade 21 moves away from the main cutting edge 20 in the left-right direction (towards the left), it extends slightly toward the rear (+Y side) in a straight line.

[0052] The convex curved blade 22 is positioned on the short side 11b. In the left-right direction, the convex curved blade 22 is positioned between the main cutting blade 20 and the wiper blade 21. The convex curved blade 22 is located inside the wiper blade 21 in the left-right direction (specifically, to the right of the wiper blade 21 (+X side)). In a plan view of the insert, the convex curved blade 22 has a curved shape that is convex toward the front side (-Y side).

[0053] The outer end of the convex curved blade 22 in the left-right direction (specifically, the left end) is smoothly connected to the inner end of the wiper blade 21 in the left-right direction (specifically, the right end). The inner end of the convex curved blade 22 in the left-right direction (specifically, the right end) is smoothly connected to the left end of the main cutting blade 20.

[0054] The inner circumferential corner blade 23 is positioned at the corner portion 11c. The inner circumferential corner blade 23 is positioned adjacent to the wiper blade 21 on its outer side in the left-right direction (specifically, on the left side (-X side)). In a plan view of the insert, the inner circumferential corner blade 23 has a curved shape that is convex toward the front side (-Y side) and outward in the left-right direction (specifically, on the left side). The inner end (right end) of the inner circumferential corner blade 23 in the left-right direction is smoothly connected to the outer end (left end) of the wiper blade 21 in the left-right direction. The inner circumferential corner blade 23 curves toward the rear side (+Y side) as it extends outward in the left-right direction (left side) from the connection point with the wiper blade 21.

[0055] The mounting hole 15 extends in the thickness direction inside the cutting insert 1 and opens on the upper surface 11 and the lower surface 12. The mounting hole 15 has a circular cross-section perpendicular to the central axis C. The central axis of the mounting hole 15 is arranged coaxially with the central axis C. The mounting hole 15 has a multi-stage circular hole shape. The inner diameter of the upper end opening of the mounting hole 15 is larger than the inner diameter of the lower end opening.

[0056] Now, we will explain the other components of the upper surface 11. As shown in Figure 1, the upper surface 11 has a boss surface 24, a breaker 25, a land surface 26, an upper bottom surface 27, and a honing surface 28.

[0057] The boss surface 24 is positioned around the mounting hole 15. The boss surface 24 forms an annular shape that surrounds the mounting hole 15 from the radially outer side to the entire circumference, and specifically, it is a circular ring shape centered on the central axis C. The boss surface 24 has a planar shape that extends in a direction perpendicular to the central axis C (XY plane direction).

[0058] In this embodiment, the width dimension of the boss surface 24 differs from one another in each part in the circumferential direction. Specifically, the width dimension of the boss surface 24 refers to the radial dimension at each position in the circumferential direction of the boss surface 24, and may hereafter be simply referred to as the boss surface width. The minimum value of the boss surface width is, for example, 0.15 mm or more.

[0059] The boss surface 24 has a pair of long-side planar portions 24a positioned closest to the long side 11a and a pair of short-side planar portions 24b positioned closest to the short side 11b. In this embodiment, the boss surface width of the long-side planar portions 24a of the boss surface 24 is larger than the boss surface width of the short-side planar portions 24b. Specifically, the boss surface width of the long-side planar portions 24a is, for example, about 0.19 mm, and the boss surface width of the short-side planar portions 24b is, for example, about 0.16 mm.

[0060] The breaker 25 is positioned between the short side 11b, the long side 11a, the corner portion 11c, and the boss surface 24, and is formed as a recess from the upper surface 11. In the insert plan view shown in Figure 1, the breaker 25 extends along the cutting edge 14. As the breaker 25 moves radially inward from the cutting edge 14, it extends downward in the thickness direction (-Z side). That is, the breaker 25 has an inclined surface shape that is inclined with respect to a virtual plane perpendicular to the central axis C. The angle at which the breaker 25 is inclined with respect to the virtual plane (virtual plane VS described later) (inclination angle θ2 described later) is, for example, about 12 to 14°. The angle (inclination angle θ2) of the breaker 25 differs from one another in each part of the breaker 25.

[0061] The breaker 25 includes an outer circumferential blade breaker portion 25a positioned radially inward of the outer circumferential blade 18, a corner blade breaker portion 25b positioned radially inward of the corner blade 19, a main cutting blade breaker portion 25c positioned radially inward of the main cutting blade 20, a wiper blade breaker portion 25d positioned radially inward of the wiper blade 21, a convex curve blade breaker portion 25e positioned radially inward of the convex curve blade 22, and an inner circumferential corner blade breaker portion 25f positioned radially inward of the inner circumferential corner blade 23.

[0062] The outer periphery breaker portion 25a extends along the outer periphery blade 18. The front-to-back dimension of the outer periphery breaker portion 25a corresponds to the front-to-back dimension (blade length dimension) of the outer periphery blade 18. In other words, the front-to-back dimension of the outer periphery breaker portion 25a and the front-to-back dimension of the outer periphery blade 18 are approximately the same. To put it another way, the portion of the long side 11a that corresponds to the outer periphery breaker portion 25a in the front-to-back direction (the portion that extends along the outer periphery breaker portion 25a) functions as the outer periphery blade 18. Note that the outer periphery blade 18 may be a dummy cutting edge that is not used for cutting.

[0063] The outer periphery blade breaker portion 25a extends downward (towards the -Z side) as it moves inward in the left-right direction (specifically, towards the left side (-X side)). As shown in Figure 4, the outer periphery blade breaker portion 25a has an inclined surface shape that slopes downward as it moves away from the outer periphery blade 18 towards the inside of the upper surface 11. The angle of inclination (angle of inclination) θ2 of the outer periphery blade breaker portion 25a with respect to a virtual plane VS that extends in the direction perpendicular to the central axis C (XY plane direction) is kept constant along the direction in which the outer periphery blade 18 extends (front-back direction). Specifically, the angle of inclination θ2 of the outer periphery blade breaker portion 25a is, for example, about 14°.

[0064] As shown in Figure 1, the outer peripheral blade breaker section 25a has a constant width section 25g in which the breaker width dimension is constant in the front-rear direction, and a width-changing section 25h in which the breaker width dimension changes as it moves toward the front-rear direction. Here, the breaker width dimension refers to the width dimension in the direction perpendicular to the cutting edge 14 at each position (each component) along the cutting edge 14 of the breaker 25 in a plan view of the insert with the top surface 11 facing forward, as shown in Figure 1, and the same applies in the following explanation.

[0065] The constant-width section 25g is located at the front end of the outer peripheral blade breaker section 25a. The width-changing section 25h is located behind (to the +Y side of) the constant-width section 25g and is connected to the constant-width section 25g. The breaker width dimension of the width-changing section 25h decreases as it moves towards the rear.

[0066] The corner blade breaker section 25b extends along the corner blade 19. The corner blade breaker section 25b is located adjacent to the outer peripheral blade breaker section 25a on the front side (-Y side) of the outer peripheral blade breaker section 25a. The breaker width dimension of the corner blade breaker section 25b gradually increases as it moves away from the connection point with the outer peripheral blade breaker section 25a along the direction in which the corner blade 19 extends. That is, the breaker width dimension of the corner blade breaker section 25b increases as it moves from the long side 11a to the short side 11b along the corner section 11c.

[0067] As shown in Figure 5, the corner blade breaker portion 25b has an inclined surface that slopes downward as it moves away from the corner blade 19 towards the inside of the upper surface 11. The angle θ2 at which the corner blade breaker portion 25b is inclined with respect to the virtual plane VS decreases as it moves along the corner portion 11c from the long side 11a towards the short side 11b. Specifically, the inclination angle θ2 of the corner blade breaker portion 25b is, for example, about 12 to 14°.

[0068] As shown in Figure 1, the main cutting edge breaker section 25c extends along the main cutting edge 20. The main cutting edge breaker section 25c is located adjacent to the corner cutting edge breaker section 25b on the inside in the left-right direction (specifically, on the left side (-X side)). The breaker width dimension of the main cutting edge breaker section 25c is constant along the direction in which the main cutting edge 20 extends.

[0069] The main cutting edge breaker section 25c extends downward (-Z side) as it moves toward the rear (+Y side). As shown in Figure 6, the main cutting edge breaker section 25c has an inclined surface shape that slopes downward as it moves away from the main cutting edge 20 toward the inside of the upper surface 11. The angle θ2 at which the main cutting edge breaker section 25c is inclined with respect to the virtual plane VS is kept constant along the direction in which the main cutting edge 20 extends. Specifically, the inclination angle θ2 of the main cutting edge breaker section 25c is, for example, about 12°.

[0070] As shown in Figure 1, the wiper blade breaker section 25d extends along the wiper blade 21. The wiper blade breaker section 25d is located on the opposite side of the main cutting blade breaker section 25c from the corner blade breaker section 25b in the left-right direction (specifically, on the left side (-X side) of the main cutting blade breaker section 25c). The breaker width dimension of the wiper blade breaker section 25d is constant along the direction in which the wiper blade 21 extends.

[0071] The wiper blade breaker portion 25d extends downward (-Z side) as it moves toward the rear (+Y side). As shown in Figure 7, the wiper blade breaker portion 25d has an inclined surface that slopes downward as it moves away from the wiper blade 21 toward the inside of the upper surface 11. The angle θ2 at which the wiper blade breaker portion 25d is inclined with respect to the virtual plane VS is kept constant along the direction in which the wiper blade 21 extends. Specifically, the inclination angle θ2 of the wiper blade breaker portion 25d is, for example, about 12°.

[0072] As shown in Figure 1, the convex curved blade breaker section 25e is positioned between the main cutting blade breaker section 25c and the wiper blade breaker section 25d in the left-right direction. Both ends of the convex curved blade breaker section 25e in the left-right direction are connected to the main cutting blade breaker section 25c and the wiper blade breaker section 25d. The convex curved blade breaker section 25e is located inside the wiper blade breaker section 25d in the left-right direction (specifically, to the right (+X side) of the wiper blade breaker section 25d).

[0073] The convex curved blade breaker section 25e extends downward (-Z side) as it moves toward the rear (+Y side). Although not specifically shown in the figures, the convex curved blade breaker section 25e has an inclined surface shape that slopes downward as it moves away from the convex curved blade 22 toward the inside of the upper surface 11. The angle θ2 at which the convex curved blade breaker section 25e is inclined with respect to the virtual plane VS is kept constant along the direction in which the convex curved blade 22 extends. Specifically, the inclination angle θ2 of the convex curved blade breaker section 25e is, for example, about 12°.

[0074] The inner circumferential corner blade breaker section 25f extends along the inner circumferential corner blade 23. The inner circumferential corner blade breaker section 25f is located adjacent to the wiper blade breaker section 25d on its left-right outer side (specifically, on the left side (-X side)). The breaker width dimension of the inner circumferential corner blade breaker section 25f decreases as it moves away from the connection point with the wiper blade breaker section 25d along the direction in which the inner circumferential corner blade 23 extends.

[0075] Although not specifically shown in the diagram, the inner circumferential corner blade breaker portion 25f has an inclined surface shape that slopes downward as it moves away from the inner circumferential corner blade 23 towards the inside of the upper surface 11. The angle θ2 at which the inner circumferential corner blade breaker portion 25f is inclined with respect to the virtual plane VS increases as it moves away from the connection portion with the wiper blade breaker portion 25d along the direction in which the inner circumferential corner blade 23 extends.

[0076] The land surface 26 extends along at least the long side 11a and the corner portion 11c, and is located outside the breaker 25. In this embodiment, the land surface 26 extends along the long side 11a, the corner portion 11c, and the short side 11b. The land surface 26 is planar in shape perpendicular to the central axis C. The boss surface 24 and the land surface 26 are located on the same virtual plane VS parallel to the lower surface 12. That is, the boss surface 24 and the land surface 26 are located at the same position (height) in the thickness direction.

[0077] The land surface 26 includes a long side land surface 26a extending along the long side 11a, a corner land surface 26c extending along the corner portion 11c, and a short side land surface 26b extending along the short side 11b.

[0078] The long side land surface 26a is positioned on the inside of the long side 11a on the upper surface 11, with a predetermined distance (the honing width of the honing 28 described later) between it and the long side 11a. The long side land surface 26a extends along the entire length of the long side 11a, parallel to the long side 11a. The long side land surface 26a extends in a straight line along the front-to-back direction.

[0079] The land width of the long side land surface 26a is constant along its entire length in the direction in which the long side land surface 26a extends (front-to-back direction). Here, the land width refers to the width dimension in the direction perpendicular to the outer edge (long side 11a, corner portion 11c, or short side 11b) of the upper surface 11 at each position (each component) of the land surface 26 in the insert plan view shown in Figure 1, and the same applies in the following explanation. Note that land width may also be referred to as land width dimension.

[0080] The corner land surface 26c is positioned inside the corner portion 11c on the upper surface 11, with a predetermined distance (the honing width of the honing 28 described later) between it and the corner portion 11c. The corner land surface 26c extends alongside the corner portion 11c along the entire length of the corner portion 11c (corner blade 19). The rear end of the corner land surface 26c is connected to the front end of the long side land surface 26a. The corner land surface 26c extends in a curved shape (convex curve shape) toward the front (-Y side) from the connection point with the long side land surface 26a, toward the left side (-X side).

[0081] The corner land surface 26c has a land width reduction section 26d along the corner portion 11c, where the land width decreases as it moves from the long side 11a towards the short side 11b. In this embodiment, the land width reduction section 26d is arranged along the entire length of the corner land surface 26c that extends along the corner portion 11c. That is, the land width reduction section 26d is provided from the end on the long side 11a side of the corner land surface 26c to the end on the short side 11b side. Therefore, as the corner land surface 26c moves away from the connection point with the long side land surface 26a in the direction in which the corner land surface 26c extends, the land width of the corner land surface 26c gradually decreases along its entire length.

[0082] As shown in Figures 4 and 5, the land width W of the corner land surface 26c is set to be less than or equal to the land width W of the long side land surface 26a. In other words, the land width W of the long side land surface 26a is set to be greater than or equal to the land width W of the corner land surface 26c. In this embodiment, the maximum value of the land width W of the corner land surface 26c (land width W at the rear end of the corner land surface 26c) and the land width W of the long side land surface 26a are the same.

[0083] As shown in Figure 1, the short side land surface 26b is positioned inside the short side 11b on the upper surface 11, with a predetermined gap (the honing width of the honing 28 described later) between it and the short side 11b. The short side land surface 26b extends alongside the short side 11b for at least a portion of its total length. In this embodiment, the right end of the short side land surface 26b is connected to the left end of the corner land surface 26c.

[0084] The land width of the short-side land surface 26b may be constant along the direction in which the short-side land surface 26b extends, or it may differ from one another at each position along the direction in which the short-side land surface 26b extends. Furthermore, the land width of the short-side land surface 26b may gradually change along the direction in which the short-side land surface 26b extends. As shown in Figures 5 to 7, the land width W of the short-side land surface 26b is set to be less than or equal to the land width W of the corner land surface 26c.

[0085] In this embodiment, the land width W of the long side land surface 26a shown in Figure 4 is, for example, about 0.167 mm, and the land width W of the short side land surface 26b shown in Figures 6 and 7 is, for example, about 0.03 mm. Furthermore, the land width W of the corner land surface 26c shown in Figure 5 is set between the land width W of the long side land surface 26a and the land width W of the short side land surface 26b, and changes along the direction in which the corner portion 11c extends (the direction in which the corner land surface 26c extends).

[0086] As shown in Figure 1, the short side land surface 26b has a main cutting blade land surface 26e that extends linearly along the main cutting blade 20, a wiper blade land surface 26f that extends linearly along the wiper blade 21, and a convex curved blade land surface 26g that extends in a curved shape (convex curve) along the convex curved blade 22. In Figures 6 and 7, in this embodiment, the land width W of the main cutting blade land surface 26e is set to be greater than or equal to the land width W of the wiper blade land surface 26f.

[0087] As shown in Figure 1, the top bottom portion 27 is positioned around the boss surface 24 and has a concave shape that is recessed from the top surface 11. The top bottom portion 27 forms an annular shape that surrounds the boss surface 24 from the radially outer side to the entire circumference. The top bottom portion 27 is located at the lower end in the thickness direction of the top surface 11. In a plan view of the insert, the top bottom portion 27 has a portion located between the breaker 25 and the boss surface 24, and a portion located between the long side land surface 26a and the boss surface 24.

[0088] The honing 28 extends along the outer periphery of the upper surface 11, i.e., along the long side 11a, the corner portion 11c, and the short side 11b. In this embodiment, the honing 28 is formed around the entire circumference of the outer periphery of the upper surface 11. The honing 28 is connected to the cutting edge 14 and extends along the cutting edge 14.

[0089] The honing width of the honing 28 is constant along its entire length (around its circumference). Here, the honing width refers to the width dimension in the direction perpendicular to the outer edge (long side 11a, corner portion 11c, or short side 11b) of the upper surface 11 at each position of the honing 28 in the insert plan view shown in Figure 1, and the same applies in the following explanation. The honing width may also be referred to as the honing width dimension.

[0090] Specifically, in this embodiment, the honing width of the honing 28 is set to approximately 0.12 ± 0.03 mm. That is, the honing width is approximately 0.12 mm, and its allowable tolerance dimension is approximately ± 0.03 mm. Therefore, when the honing width is at the maximum allowable tolerance, at least a portion of the short side land surface 26b may disappear.

[0091] Furthermore, the honing 28 is chamfer honing. As shown in Figures 4 to 7, the honing 28 has an inclined surface shape that slopes upward as it moves from the cutting edge 14 towards the inside of the upper surface 11. The angle θ1 at which the honing 28 is inclined with respect to the virtual plane VS is constant over the entire length (around the circumference) of the honing 28. Specifically, the inclination angle θ1 of the honing 28 is, for example, about 20°.

[0092] In this embodiment, as shown in Figures 4 to 7, when viewed in a cross-sectional view perpendicular to the cutting edge 14, the angle between the virtual plane VS and the honing 28 (honing angle) is θ1, and the angle between the virtual plane VS and the breaker 25 (breaker angle) is θ2, the relationship θ1 > θ2 is satisfied.

[0093] The holder 31 is made of metal, such as steel. As shown in Figure 8, the holder 31 is columnar in shape with the rotation axis J as its center and extends in the direction of the tool axis. Specifically, the holder 31 is roughly multi-stage cylindrical. The rear end of the holder 31 in the direction of the tool axis is detachably attached to the spindle of a machine tool (not shown).

[0094] The holder 31 has a plurality of insert mounting seats 33 arranged at intervals from each other in the circumferential direction of the tool on the outer circumference of the tip of the holder 31, to which each cutting insert 1 is detachably attached, and a plurality of chip pockets 39 that are recessed from the tip surface and outer circumference of the holder 31 and are formed on the rear end side of each insert mounting seat 33 in the tool rotation direction TD and in the tool axis direction.

[0095] The insert mounting seat 33 is positioned at the tip of the holder 31 in the tool axis direction and opens to the tip surface and outer circumference of the holder 31. The insert mounting seat 33 is concave, recessed from the tip surface and outer circumference of the holder 31. The insert mounting seat 33 is formed to cut out the tip outer circumference of the wall portion of the tip pocket 39 facing the tool rotation direction TD.

[0096] The shape of the insert mounting seat 33 corresponds to the shape of the cutting insert 1, and in this embodiment, it is a rectangular hole. Specifically, the shape of the insert mounting seat 33 is a rectangular hole or a parallelogram hole.

[0097] In this embodiment, three insert mounting seats 33 are provided on the outer circumference of the tip of the holder 31 at equal pitches in the circumferential direction of the tool. The number of insert mounting seats 33 is the same as the number of cutting inserts 1. Multiple cutting inserts 1 of the same shape are mounted on the multiple insert mounting seats 33. Each cutting insert 1 is detachably attached to each insert mounting seat 33. Note that the number of insert mounting seats 33 is not limited to three; it may be two or fewer, or four or more. Furthermore, the multiple insert mounting seats 33 may be provided at unequal pitches in the circumferential direction of the tool.

[0098] The insert mounting seat 33 has a mounting surface 34 located at the end of the insert mounting seat 33 opposite to the tool rotation direction and facing the tool rotation direction TD, an inner wall surface 36 located at the inner end of the insert mounting seat 33 in the tool radial direction and facing outward in the tool radial direction, a rear end side wall surface 35 located at the rear end of the insert mounting seat 33 in the tool axial direction and facing towards the tip side in the tool axial direction, and a female screw hole 37.

[0099] When the cutting insert 1 is mounted on the insert mounting seat 33, the mounting surface 34 contacts the lower surface (seat surface) 12 of the cutting insert 1. The mounting surface 34 supports the cutting insert 1 from the direction opposite to the tool rotation (see Figures 9 and 10).

[0100] Furthermore, when the cutting insert 1 is mounted on the insert mounting seat 33, the inner wall surface 36 contacts the side surface 13 of the cutting insert 1. Specifically, the inner wall surface 36 contacts the left side wall 17a of the side surface 13 of the cutting insert 1, which faces inward in the tool radial direction. The inner wall surface 36 supports the cutting insert 1 from the inside in the tool radial direction.

[0101] Furthermore, when the cutting insert 1 is mounted on the insert mounting seat 33, the rear end side wall surface 35 contacts the side surface 13 of the cutting insert 1. Specifically, the rear end side wall surface 35 contacts the rear side wall 16b of the side surface 13 of the cutting insert 1, which faces the rear end side in the tool axis direction. The rear end side wall surface 35 supports the cutting insert 1 from the rear end side in the tool axis direction.

[0102] The female screw hole 37 opens into the mounting surface 34 and extends in a direction substantially perpendicular to the direction in which the mounting surface 34 expands. In this embodiment, the female screw hole 37 is a through hole. However, it is not limited to this, and the female screw hole 37 may be a bottomed hole that opens only into the mounting surface 34. The female screw hole 37 has a female screw portion on its inner circumferential surface.

[0103] As shown in Figures 9 and 10, the fastening member 38 is, for example, a clamp screw. The fastening member 38 detachably secures the cutting insert 1 to the insert mounting seat 33 of the holder 31. Specifically, the fastening member 38 is inserted into the mounting hole 15 of the cutting insert 1 and screwed into the female screw hole 37 of the insert mounting seat 33.

[0104] When the cutting insert 1 is attached to the holder 31, the upper surface 11 and lower surface 12 of the cutting insert 1 face the circumferential direction of the tool. Specifically, the upper surface (rake face) 11 faces the tool rotation direction TD, and the lower surface (seat surface) 12 faces the opposite direction of tool rotation. In other words, the cutting insert 1 in this embodiment is a so-called horizontal-blade type insert.

[0105] As shown in Figure 10, with the cutting insert 1 mounted on the insert mounting seat 33, the cutting edge 14 protrudes outward in the tool radial direction from the outer peripheral surface of the holder 31, and also protrudes towards the tip in the tool axial direction from the tip surface of the holder 31. The lowest point L of the tool, which is located furthest towards the tip in the tool axial direction on the cutting edge 14, is located on a virtual surface P (corresponding to the machined surface (finished surface) of the workpiece) that extends in a direction perpendicular to the rotation axis J.

[0106] In this embodiment, the lowest point L of the tool is located on the wiper blade 21. Also, as shown in Figure 10, when viewing the replaceable tip rotary cutting tool 30 from the radial direction with the top surface 11 facing forward, the cutting angle K formed between the main cutting edge 20 and the virtual surface P is between 5° and 25°. In this way, by positioning the lowest point L of the tool on the wiper blade 21, the width of the chip is increased, which suppresses the rise in cutting temperature during machining. This improves the life of the cutting edge. In addition, setting the cutting angle K to 5° or more improves the ability to bite into the workpiece. Setting the cutting angle K to 25° or less prevents the chip from becoming excessively thick, resulting in good chip evacuation.

[0107] In the cutting insert 1 of this embodiment described above, the boss surface 24 and land surface 26 provided on the upper surface 11 are on the same virtual plane VS parallel to the lower surface 12. Therefore, even if a breaker 25 is provided on the upper surface 11, the boss surface 24 and land surface 26 of the upper surface 11 and the lower surface 12 can secure an area (clamping area) to clamp the cutting insert 1 from the thickness direction. The cutting insert 1 can be stably clamped and fixed from the thickness direction by a clamping jig or the like (not shown), ensuring clamping stability during insert manufacturing, and allowing the cutting edge 14 to be formed accurately by applying a grinding wheel to the outer circumference of the insert.

[0108] Furthermore, the upper surface 11 has a large clamping area provided by the boss surface 24 and the land surface 26. Therefore, when the cutting insert 1 is clamped from the thickness direction during insert manufacturing, the concentration of pressure near the cutting edge 14 on the upper surface 11 is suppressed. This suppresses damage to the cutting insert 1.

[0109] Furthermore, the land surface 26 has at least a long side land surface 26a and a corner land surface 26c. The long side land surface 26a extends along the long side 11a, and therefore has a long length (overall dimension). Furthermore, the land width W of the long side land surface 26a is greater than or equal to the land width W of the corner land surface 26c. As a result, the long side land surface 26a has a large surface area. This allows for a larger clamping area on the upper surface 11 during insert manufacturing, improving clamping stability and enhancing the forming accuracy of the cutting edge 14. In addition, the pressure acting on the upper surface 11 is distributed over a wider area, thus further suppressing damage to the cutting insert 1.

[0110] Furthermore, the corner land surface 26c has a land width reduction portion 26d. In the land width reduction portion 26d, the land width W decreases as it moves along the corner portion 11c from the long side 11a to the short side 11b. As a result, the land width W of the corner land surface 26c is smaller in the short side portion than in the long side portion. Consequently, the land width W of the short side land surface 26b adjacent to the short side portion of the corner land surface 26c and extending along the short side 11b (or the width of the top portion, etc., corresponding to the short side land surface 26b that disappeared due to the formation of honing 28) is also kept small. Therefore, the cutting resistance of the main cutting edge 20, the convex curved blade 22, and the wiper blade 21 (hereinafter sometimes referred to as the main cutting edge 20, etc.) arranged on the short side 11b is reduced, and the cutting performance of the main cutting edge 20, etc. can be improved.

[0111] As described above, according to this embodiment, even if the breaker 25 is provided, the cutting insert 1 can be stably clamped and fixed from the thickness direction during manufacturing, damage to the cutting insert 1 can be suppressed, and the cutting performance during cutting can be further improved.

[0112] In this embodiment, the land surface 26 has a short-side land surface 26b that extends along the short side 11b, and the land width W of the short-side land surface 26b is less than or equal to the land width W of the corner land surface 26c.

[0113] In this case, since the land surface 26 also has a shorter side land surface 26b, a larger overall surface area can be secured for the land surface 26. As a result, a larger clamping area can be secured for the upper surface 11 during insert manufacturing, improving clamping stability and further enhancing the forming accuracy of the cutting edge 14. In addition, the pressure acting on the upper surface 11 is distributed over a wider area, further suppressing damage to the cutting insert 1.

[0114] Furthermore, the provision of the short-side land surface 26b improves the cutting edge strength of the main cutting edge 20 and other blades located on the short side 11b. This suppresses chipping of the cutting edge of the main cutting edge 20 and other blades. On the other hand, the land width W of the short-side land surface 26b is set to be less than or equal to the land width W of the corner land surface 26c. This allows the cutting resistance of the main cutting edge 20 and other blades to be kept low, thereby improving the cutting performance of the main cutting edge 20 and other blades.

[0115] In this embodiment, the upper surface 11 is connected to the cutting edge 14 and has a honing 28 that extends along the cutting edge 14. In a cross-sectional view perpendicular to the cutting edge 14, when the angle between the virtual plane VS parallel to the lower surface 12 and the honing 28 is θ1, and the angle between the virtual plane VS and the breaker 25 is θ2, the relationship θ1 > θ2 is satisfied.

[0116] In this case, angle θ1 is larger than angle θ2, meaning the inclination angle θ2 of the breaker 25 is smaller, which allows for a larger wall thickness of the cutting insert 1. This provides the cutting insert 1 with high cutting edge strength.

[0117] In this embodiment, the land width W of the main cutting blade land surface 26e is set to be greater than or equal to the land width W of the wiper blade land surface 26f. In this case, the land width W of the main cutting edge land surface 26e is increased, which ensures the cutting edge strength of the main cutting edge 20. Also, the land width W of the wiper blade land surface 26f is reduced, which improves the grip of the wiper blade 21 on the workpiece and enhances the cutting performance of the wiper blade 21.

[0118] In this embodiment, the width of the boss surface 24a on the longer side is made larger than the width of the boss surface 24b on the shorter side. In this case, the boss surface width of the long-side flat portion 24a is larger than the boss surface width of the short-side flat portion 24b, thereby ensuring a larger overall surface area of ​​the boss surface 24. This allows for a larger clamping area on the upper surface 11 during insert manufacturing, improving clamping stability and enhancing the forming accuracy of the cutting edge 14.

[0119] 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 will be explained below. In the illustration of modified examples, the same reference numerals are used for components that are the same as those in the embodiments described above, and the differences will be mainly described below.

[0120] In the embodiments described above, an example was given in which the land surface 26 has a short-side land surface 26b, but the invention is not limited to this. Although not specifically shown in the figures, the upper surface 11 of the cutting insert 1 has a top that extends along the short side 11b and is located outside the breaker 25, and the width of the top may be less than or equal to the land width W of the corner land surface 26c.

[0121] In this case, the top portion extending along the short side 11b may have a narrow, planar portion in part, or it may have a ridge-like portion. The width of this top portion is set to be less than or equal to the land width W of the corner land surface 26c. Therefore, the cutting resistance of the main cutting edge 20 etc., which is positioned on the short side 11b, can be kept low, and the cutting performance of the main cutting edge 20 etc. can be improved.

[0122] Furthermore, the land surface 26 does not necessarily have to have a short side land surface 26b that extends along the short side 11b. In this case, since a planar short-side land surface 26b extending along the short side 11b is not provided, the cutting resistance of the main cutting edge 20 can be kept low, and the cutting performance of the main cutting edge 20 can be further improved.

[0123] Furthermore, in the above-described embodiment, an example was given in which the land width reduction portion 26d is arranged along the entire length of the corner land surface 26c extending along the corner portion 11c, but the invention is not limited to this. Although not specifically shown, the land width reduction portion 26d does not have to be provided along the entire length of the corner land surface 26c. That is, the land width reduction portion 26d may be provided only in a part of the corner land surface 26c. In this case, the land width W may be constant along the corner portion 11c in the portion of the corner land surface 26c other than the land width reduction portion 26d. However, it is preferable that the land width reduction portion 26d is arranged over more than half of the entire length of the corner land surface 26c.

[0124] Here, Figures 11 to 17 show a modified cutting insert 10 according to the embodiment described above. In the modified version shown in Figures 11 to 17, the upper surface 11 of the cutting insert 10 does not have honing 28. In this modified version, the land surface 26 is (directly) connected to the cutting edge 14 and extends along the cutting edge 14.

[0125] In this modified example, the land width W of the long side land surface 26a is, for example, about 0.287 mm, and the land width W of the short side land surface 26b is, for example, about 0.15 mm. Furthermore, the land width W of the corner land surface 26c is set between the land width W of the long side land surface 26a and the land width W of the short side land surface 26b, and changes along the direction in which the corner portion 11c extends (the direction in which the corner land surface 26c extends).

[0126] According to the above modification, a larger surface area can be secured for the entire land surface 26. As a result, a larger clamping area can be secured for the upper surface 11 during insert manufacturing, improving clamping stability and further enhancing the forming accuracy of the cutting edge 14. In addition, the pressure acting on the upper surface 11 is distributed over a wider area, further suppressing damage to the cutting insert 1.

[0127] Furthermore, although the above-described embodiment shows the cutting insert 1 as being rectangular or parallelogram-shaped, it is not limited to these. The cutting insert 1 may be square or rhombic, or the like, with the central axis C as the center. In addition, the cutting insert 1 may be polygonal in shape other than a rectangular plate.

[0128] Although not specifically shown in the figures, the holder 31 may also have coolant holes that extend inside the holder 31 and open toward the vicinity of the cutting edge 14 of each cutting insert 1 that is positioned in the plurality of insert mounting seats 33.

[0129] Furthermore, in the above-described embodiment, the tool rotation direction TD, in which the tool is rotated, is set to a counterclockwise direction when viewed from the tip side in the tool axis direction (see Figure 9). However, the tool rotation direction TD is not limited to this configuration; it may also be a clockwise direction when viewed from the tip side in the tool axis direction. In other words, the present invention is applicable to cutting inserts and replaceable-tip rotary cutting tools that differ in operation from the above-described embodiment.

[0130] 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]

[0131] According to the cutting insert of the present invention, even if a breaker is provided, the cutting insert can be stably clamped and fixed from the thickness direction during manufacturing, and damage to the insert can be suppressed, while the cutting performance can be further improved during cutting. Therefore, it has industrial applicability. [Explanation of Symbols]

[0132] 1, 10…Cutting insert, 11…Top surface, 11a…Long side, 11b…Short side, 11c…Corner section, 12…Bottom surface, 13…Side surface, 14…Cutting edge, 15…Mounting hole, 19…Corner edge, 20…Main cutting edge, 24…Boss surface, 25…Breaker, 26…Land surface, 26a…Long side land surface, 26b…Short side land surface, 26c…Corner land surface, 26d…Land width reduction section, 28…Honing, VS…Virtual plane, W…Land width, θ1, θ2…Angle

Claims

1. A cutting insert having a polygonal plate shape, The cutting insert has polygonal upper and lower surfaces facing the thickness direction, The side surface connected to the upper surface and the lower surface, A cutting blade is positioned on the ridge where the upper surface and the side surface are connected, The cutting insert comprises a mounting hole that penetrates in the thickness direction, The aforementioned upper surface is, The short side is arranged on the outer periphery of the upper surface, The upper surface is positioned on its outer periphery, and has a longer side that is longer than the shorter side, It has corner portions arranged on the outer periphery of the upper surface and connected to the short side and the long side, The aforementioned cutting edge is The main cutting edge is positioned on the short side, It has a corner blade positioned at the corner portion, The aforementioned upper surface is, A boss surface positioned around the aforementioned mounting hole, A breaker is positioned between the short side, the long side, and the corner portion and the boss surface, and is recessed from the upper surface. It has at least a land surface that extends along the long side and the corner portion and is located outside the breaker, The boss surface and the land surface are located on the same virtual plane parallel to the lower surface. The aforementioned land surface is A long side land surface extending along the aforementioned long side, It has a corner land surface that extends along the corner portion, The land width of the aforementioned long side land surface is greater than or equal to the land width of the aforementioned corner land surface. The corner land surface has a land width reduction section along the corner portion, where the land width decreases as you move from the longer side towards the shorter side. Cutting insert.

2. The land surface has a short-side land surface that extends along the short side, The land width of the short side land surface is less than or equal to the land width of the corner land surface. The cutting insert according to claim 1.

3. The upper surface extends along the short side and has a top portion located on the outside of the breaker. The width of the top portion is less than or equal to the land width of the corner land surface. The cutting insert according to claim 1.

4. The aforementioned land surface does not have a short-side land surface extending along the short side. The cutting insert according to claim 1.

5. The upper surface has honing that is connected to the cutting edge and extends along the cutting edge. In a cross-sectional view perpendicular to the cutting edge, when the angle between the virtual plane and the honing is θ1 and the angle between the virtual plane and the breaker is θ2, the relationship θ1 > θ2 is satisfied. A cutting insert according to any one of claims 1 to 4.

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