Cutting tools

Abstract

The present invention provides a cutting tool that offers excellent chip evacuation and suppresses cutting edge chipping during turning operations such as finishing. [Solution] The blade portion 12 is provided with a projection 5 that protrudes from the rake face 1, and the projection 5 has a projection ridge 51 that extends forward as it moves away from the bisector in the left-right direction, a first inclined surface 52 that is positioned between the projection ridge 51 and the bisector and extends downward as it moves away from the projection ridge 51, and a second inclined surface 53 that is positioned on the opposite side of the bisector of the projection ridge 51 and extends downward as it moves away from the projection ridge 51, and the rake face 1 has a first rake face 16 that extends downward as it moves inward from the cutting edge 3 to the inside of the rake face 1, and a second rake face 17 that is positioned inside the first rake face 16 and extends downward as it moves inward from the connection portion with the first rake face 16, and the second rake angle of the second rake face 17 is larger than the first rake angle of the first rake face 16.

Description

Technical Field

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

Background Art

[0002] Conventionally, as a cutting tool used for turning processing, for example, a cutting insert disclosed in Patent Document 1 is known. The cutting insert described in Patent Document 1 has a base portion, and a cutting portion containing a sintered body of cubic boron nitride or diamond and joined to the base portion. In Patent Document 1, representative examples of workpieces to be turned by the cutting insert include hardened steel, carbon steel, alloy steel, stainless steel, cast iron, non-ferrous metals and the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] In conventional cutting tools, during turning processing such as finishing, as in the region indicated by the circled number 3 in the graph of Fig. 12, when the depth of cut (ap) and feed (fr) are small, for example, ap ≤ 0.1 mm and fr ≤ 0.1 mm / rev (hereinafter may be simply referred to as low depth of cut or the like), it is difficult to properly control chip flow, and there is a risk that thin and elongated chips will wind around the workpiece, a part of the machine tool (chuck), the tool or the like. In addition, as in the region indicated by the circled number 1 in the graph of Fig. 12, when the depth of cut (ap) and feed (fr) are large, for example, ap = 0.3 mm and fr = 0.3 mm / rev (hereinafter may be simply referred to as high depth of cut or the like), a strong load is applied to the cutting edge due to chip clogging on the rake face wear or the like, which may cause chipping of the cutting edge.

[0005] The present invention aims to provide a cutting tool that can achieve excellent chip evacuation and suppress cutting edge chipping during turning operations such as finishing. [Means for solving the problem]

[0006] To solve the above problems, the present invention provides the following means.

[0007] [Aspect 1 of the present invention] The cutting edge comprises a blade containing cubic boron nitride or diamond, the blade comprising a rake face, a relief face, a cutting edge positioned on the ridge where the rake face and the relief face are connected and forming a V-shape in a plan view with the rake face facing forward, and a projection positioned on the rake face and protruding from the rake face, the cutting edge comprising a corner blade forming a convex curve, and a pair of straight blades connected to both ends of the corner blade and each extending in a straight line, the direction in which the bisectors of the pair of straight blades extend in the plan view is defined as the front-to-back direction, the direction perpendicular to the bisectors in the 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-to-down direction, the projection is a projection that extends forward as it moves away from the bisectors in the left-to-right direction in the plan view. A cutting tool having a ridge, a first inclined surface positioned in a plan view between the protruding ridge and the bisector, extending downward as it moves away from the protruding ridge, and a second inclined surface positioned in a plan view on the opposite side of the bisector of the protruding ridge, extending downward as it moves away from the protruding ridge, wherein the rake face has a first rake face that extends downward as it moves inward from the cutting edge to the inside of the rake face, and a second rake face positioned inside the first rake face, extending downward as it moves inward from the connection portion with the first rake face, wherein the second rake angle at which the second rake face is inclined with respect to the first virtual plane is greater than the first rake angle at which the first rake face is inclined with respect to the first virtual plane that extends perpendicular to the vertical direction.

[0008] The cutting tool of the present invention is, for example, a cutting insert for an indexable cutting tool used in turning operations such as finishing. In this cutting tool, a projection is provided on the rake face of the cutting edge, and the ridge of this projection extends at an inclination with respect to the bisector when viewed in plan with the rake face facing forward. Specifically, the ridge of the projection extends forward as it moves away from the bisector in the left-right direction in a plan view.

[0009] Furthermore, the projection has a first inclined surface and a second inclined surface located on both sides of the projection's ridge. The first inclined surface is located on the lower side as it moves away from the projection's ridge toward the bisector, and the second inclined surface is located on the lower side as it moves away from the projection's ridge toward the opposite side of the bisector.

[0010] Therefore, in the finishing machining area, when the depth of cut (ap) and feed rate (fr) are large, for example, ap = 0.3 mm and fr = 0.3 mm / rev, the chips generated from the cutting edge by cutting come into contact with the first inclined surface and are discharged toward the side of the bisecting line of the projection (corresponding to the tool feed direction). As a result, the chips are strongly strained and curled under resistance, and are discharged in the direction of machining (tool feed direction). The strongly strained and curled chips are finely divided at approximately constant intervals and processed stably.

[0011] Furthermore, in the finishing machining area, when the depth of cut (ap) and feed rate (fr) are small, for example, ap = 0.1 mm or less and fr = 0.1 mm / rev or less, the chips generated from the cutting edge by cutting come into contact with the second inclined surface and are discharged in the opposite direction to the bisector of the projection (corresponding to the opposite direction to the tool feed direction). As a result, the chips are less susceptible to resistance and load, and a high chip discharge rate is maintained. Because such chips have a high discharge rate, they are less likely to accumulate near the machined surface of the workpiece and are discharged outside the machining area. Therefore, it is possible to suppress problems such as thin, elongated chips getting tangled in the workpiece, parts of the machine tool (chuck), tools, etc.

[0012] As described above, according to the present invention, appropriate chip removal can be achieved by using different inclined surfaces (first inclined surface, second inclined surface) that act on the chips depending on the machining conditions (depending on whether it is high depth of cut or low depth of cut). Therefore, the chip removal performance in the finishing machining area can be stably improved. In addition, it is possible to prevent the shutdown of production equipment due to chip entanglement with the workpiece or tools, thereby improving production efficiency (machining efficiency).

[0013] Furthermore, the rake face extends downwards as it moves inward (away from the cutting edge towards the rake face in a plan view). As a result, the cutting edge is given a positive rake angle, which enhances cutting performance. This reduces the constraint on chips and lowers the load on the cutting edge.

[0014] Furthermore, the rake face has a first rake face adjacent to the cutting edge, and a second rake face positioned inside the first rake face, with a larger rake angle than the first rake face. Therefore, even if rake face wear occurs on the first rake face as machining progresses, the chips that enter the worn rake face can be stably flowed to the second rake face without clogging. This suppresses chip clogging due to rake face wear and enables stable cutting.

[0015] Specifically, unlike the present invention, in conventional products where a stepped rake angle is not provided on the rake face (as shown in Figure 11(a)), when rake face wear occurs, chips that enter the rake face wear can clog, placing a heavy load on the cutting edge and potentially causing chipping. On the other hand, in the present invention, (as shown in Figure 11(b)) chips that enter the rake face wear are directed toward the second rake face, thus suppressing chip clogging and chipping of the cutting edge. In particular, tool life can be extended even under machining conditions with high depth of cut and feed rate, and high cutting load (such as at high depth of cut).

[0016] Based on the above, the present invention provides excellent chip evacuation performance and suppresses cutting edge chipping during turning operations such as finishing.

[0017] [Aspect 2 of the present invention] The cutting tool according to embodiment 1, wherein the protruding ridge extends downward as it moves away from the bisector in the plan view.

[0018] In this case, the projection ridge, which is the top of the projection, extends downward as it approaches the outside of the rake face (in the direction from the rake face towards the cutting edge in a plan view). As a result, the chips generated by the cutting edge and directed toward the inside of the rake face can more easily and stably come into contact with each part of the projection (first inclined surface, second inclined surface, projection ridge). Therefore, the effects of the present invention described above are more stably achieved.

[0019] [Aspect 3 of the present invention] The cutting tool according to embodiment 1 or 2, wherein the aforementioned protruding ridge extends in a straight line.

[0020] In the above configuration, since the protruding ridges are straight, the differentiation between the first and second inclined surfaces described above can be made more stable compared to, for example, cases where the protruding ridges are curved or bent. In other words, the effect of improving chip processing is more stable. Also, because inflection points are not formed on the protruding ridges, localized loads are suppressed, thus preventing damage to the protrusions. The effects (functions) of the protrusions are maintained well over a long period of time.

[0021] [Aspect 4 of the present invention] A cutting tool according to any one of embodiments 1 to 3, wherein, in the plan view, the projection angle formed between the bisector and the projection ridge is greater than 10° and less than or equal to 45°.

[0022] When the projection angle exceeds 10°, the chip can be stably brought into contact with the first inclined surface, such as during high cutting depths. Furthermore, when the projection angle is 45° or less, the chip can be stably brought into contact with the second inclined surface, such as during low cutting depths.

[0023] [Aspect 5 of the present invention] The cutting tool according to any one of aspects 1 to 4, wherein a virtual plane including the protruding ridge line in its plane and extending along the vertical direction is defined as a second virtual plane, a virtual plane including the protruding ridge line in its plane and orthogonal to the second virtual plane is defined as a third virtual plane, and in a cross-sectional view perpendicular to the protruding ridge line, a first inclination angle formed between the third virtual plane and the first inclined surface is larger than a second inclination angle formed between the third virtual plane and the second inclined surface.

[0024] In this case, the first inclination angle is set to be larger than the second inclination angle, that is, the first inclined surface has a steep inclination (sharp inclination), so that the first inclined surface acts strongly on chips generated during high depth of cut. Therefore, chips can be more easily divided at the time of high depth of cut.

[0025] Further, the second inclination angle is set to be smaller than the first inclination angle, that is, the second inclined surface has a gentle inclination, so that when chips generated during low depth of cut come into contact with the second inclined surface, the outflow speed of the chips is maintained in a high state. Therefore, chip disposability can be more stably enhanced at the time of low depth of cut.

[0026] [Aspect 6 of the present invention] The cutting tool according to any one of aspects 1 to 5, wherein the second rake angle is 20° or less.

[0027] When the second rake angle is 20° or less, the included angle of the cutting edge is sufficiently secured. The cutting edge strength is favorably maintained, and chipping of the cutting edge can be stably suppressed.

[0028] [Aspect 7 of the present invention] The cutting tool according to any one of aspects 1 to 6, wherein in the plan view, a distance between a connection portion of the first rake face and the second rake face and the cutting edge is 0.3 mm or less.

[0029] Because the above distance is 0.3 mm or less, even if chips enter the rake face wear on the first rake face, these chips do not clog and flow stably to the second rake face. As a result, the function of suppressing cutting edge chipping by the second rake face is obtained more stably.

[0030] [Aspect 8 of the present invention] The cutting tool according to any one of embodiments 1 to 7, wherein the blade portion is provided with a vertical wall positioned on the opposite side of the rake face from the cutting edge and facing forward, the vertical wall having a lower wall surface connected to the rake face and extending upward toward the rear from the connection portion with the rake face, and an upper wall surface connected to the upper end of the lower wall surface and extending upward toward the rear from the connection portion with the lower wall surface, and in a vertical cross-sectional view along the vertical direction including the bisector, the connection portion between the first rake face and the second rake face protrudes upward with respect to a first imaginary straight line passing through the lowest point of the rake face and the highest point of the rake face, and the connection portion between the upper wall surface and the lower wall surface is recessed downward with respect to a second imaginary straight line passing through the upper front end where the upper surface of the cutting tool portion and the vertical wall are connected and the lowest point.

[0031] In the above-mentioned longitudinal cross-sectional view, the connection portion between the first rake face and the second rake face protrudes upward with respect to the first virtual straight line, thereby stably obtaining the above-mentioned effects of the two-stage rake face of the present invention.

[0032] Furthermore, in the above-mentioned vertical cross-sectional view, the connection between the upper and lower wall surfaces is recessed on the lower side relative to the second virtual straight line, allowing chips to come into contact with the vertical wall at multiple points (upper and lower wall surfaces). This distributes the force received from the chips to multiple points, suppressing wear and damage near the vertical wall.

[0033] [Aspect 9 of the present invention] The cutting tool according to any one of embodiments 1 to 8, wherein the blade portion is provided with a vertical wall positioned on the opposite side of the rake face from the cutting edge and facing forward, the vertical wall having a lower wall surface connected to the rake face and extending upward toward the rear from the connection portion with the rake face, and an upper wall surface connected to the upper end of the lower wall surface and extending upward toward the rear from the connection portion with the lower wall surface, and in a vertical cross-sectional view along the vertical direction passing through the vertical wall, the rake face and the cutting edge, the upper inclination angle of the upper wall surface with respect to the first virtual plane is greater than the lower inclination angle of the lower wall surface with respect to the first virtual plane, and the diameter dimension of the inscribed circle tangent to the three sides of the rake face, the lower wall surface and the upper wall surface is less than 1.0 mm.

[0034] In the above configuration, the upper inclination angle is greater than the lower inclination angle (the angle is steeper), allowing the chips to stably contact the upper wall surface. This stably improves chip handling performance, especially at high depths of cut.

[0035] Furthermore, by having an inscribed circle diameter of less than 1.0 mm, the chips can be stably restrained, resulting in chips that are less prone to stretching and have a curling tendency.

[0036] [Aspect 10 of the present invention] The cutting tool according to embodiment 9, wherein the upper inclination angle is 60° or less.

[0037] By keeping the upper inclination angle to 60° or less, chip clogging on the upper wall surface is less likely to occur, and the increase in cutting edge load is suppressed.

[0038] [Aspect 11 of the present invention] A cutting tool according to any one of embodiments 1 to 10, wherein, in the plan view, the first inclined surface extends to the line of the bisector.

[0039] In this case, a large surface area can be formed on the first inclined surface. When cutting at high depths, the wide chips generated from the cutting edge can be stably brought into contact with the first inclined surface. The first inclined surface allows for stable processing of the chips.

[0040] [Aspect 12 of the present invention] The cutting tool according to any one of embodiments 1 to 11, wherein the blade portion has an inclined wall that extends upward as it approaches the bisector in a direction perpendicular to the straight blade in the plan view, the straight blade has chamfered honing, the inclined wall is located below a fourth virtual plane that includes the chamfered honing in its plane, and the inclined wall has a plurality of wall grooves that extend parallel to the straight blade.

[0041] In this case, the chips come into contact with the grooves in the inclined wall, causing the inclined wall to function as a derivative (secondary) cutting edge. This improves chip breaking performance.

[0042] [Aspect 13 of the present invention] A cutting tool according to any one of embodiments 1 to 12, wherein the dimension in the front-rear direction between the front end of the corner blade and the front end of the projection is greater than 0.25 mm and less than 0.5 mm.

[0043] If the front-to-back dimension between the front end of the corner cutting edge and the front end of the projection exceeds 0.25 mm, the obstruction of the chip flow from the first rake face to the second rake face by the projection is suppressed, and chip evacuation performance is stably improved. Also, if the front-to-back dimension between the front end of the corner cutting edge and the front end of the projection is less than 0.5 mm, the chip will stably contact the projection, and chip evacuation performance will be stably improved.

[0044] [Aspect 14 of the present invention] A cutting tool according to any one of embodiments 1 to 13, wherein the blade portion has a left-right symmetrical shape with respect to a virtual plane that includes the aforementioned bisector and is aligned in the vertical direction.

[0045] In the above configuration, the cutting edge is symmetrical with respect to the reference plane (plane of symmetry) (mirror-image symmetry, mirror-surface symmetry). Therefore, the cutting tool can be used in both left-handed and right-handed applications, without any particular restrictions on the tool feed direction during turning. This increases the degree of freedom in the cutting conditions to which the cutting tool can be applied.

[0046] Furthermore, since a pair of protrusions are provided on the rake face, especially when cutting at high depths, chips that come into contact with the first inclined surface of one of the protrusions closest to the machined surface of the workpiece are then brought into contact with the other protrusion. This further improves chip removal efficiency. [Effects of the Invention]

[0047] According to the above-described aspect of the present invention, a cutting tool is provided that can achieve excellent chip evacuation and suppress cutting edge chipping during turning operations such as finishing. [Brief explanation of the drawing]

[0048] [Figure 1] Figure 1 is a perspective view showing the cutting tool of this embodiment. [Figure 2] Figure 2 is a perspective view showing a portion of a cutting tool (near the cutting edge). [Figure 3] Figure 3 is a plan view (top view) showing a part of the cutting tool (near the cutting edge). [Figure 4] Figure 4 is a front view showing a part of the cutting tool (near the cutting edge). [Figure 5] Figure 5 is a side view showing a part of the cutting tool (near the cutting edge). [Figure 6] Figure 6 is a longitudinal cross-sectional view showing the VI-VI section in Figure 3. [Figure 7] Figure 7 is a longitudinal section view (a longitudinal section view along the vertical direction including the bisector) showing the VII-VII section of Figure 3. [Figure 8] Figure 8 is a longitudinal cross-sectional view showing the section VIII-VIII in Figure 3. [Figure 9] Figure 9 shows the IX-IX section of Figure 3, which is more specifically a cross-section perpendicular to the protruding ridge line. [Figure 10] Figure 10 is a diagram illustrating the action (function) of the first and second inclined surfaces of the projection. [Figure 11] Figure 11(a) is a schematic diagram illustrating the problems that occur when rake face wear occurs on the rake face of a conventional cutting tool, and Figure 11(b) is a schematic diagram illustrating the action (function) when rake face wear occurs on the rake face of the cutting tool of this embodiment. [Figure 12] Figure 12 is a graph illustrating the magnitudes of the depth of cut (ap) and feed rate (fr) used in the finishing process. [Modes for carrying out the invention]

[0049] 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, for example, a cutting insert for an indexable cutting tool used in turning operations such as finishing. In particular, as shown in Figure 12, the cutting tool 10 of this embodiment is suitably used in the cutting conditions of depth of cut (ap) and feed rate (fr) used in the finishing region. In this embodiment, the cutting tool 10 may be simply referred to as an insert or a tool.

[0050] Although not specifically shown in the diagram, the replaceable tip cutting tool comprises a holder, a cutting tool (cutting insert) 10, and fastening members. The holder has a concave insert mounting seat located at the tip of the holder. The cutting tool 10 is detachably attached to the insert mounting seat by fastening members such as a clamp piece, clamp lever, or clamp screw.

[0051] As shown in Figure 1, 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 is, for example, a rhombic insert (cutting insert) with a shape conforming to ISO standards. 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.

[0052] 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.

[0053] The cutting tool 10 comprises a blade portion 12 and a base metal portion 11 to which the blade portion 12 is fixed. The base metal portion 11 is made of, for example, cemented carbide. The base metal portion 11 is in the shape of a polygonal plate, and in this embodiment it is in the shape of a rectangular plate such as a rhombic plate. The base metal portion 11 has a blade mounting portion 11a and a mounting hole 11b.

[0054] The blade mounting portion 11a is concave, recessed from the outer surface of the base metal portion 11. The blade mounting portion 11a is formed by recessing from one of the pair of plate surfaces (front and back) of the base metal portion 11 (front surface) and the outer peripheral surface. The blade mounting portion 11a is positioned at a predetermined corner among the multiple corners of the base metal portion 11. In the illustrated example, the blade mounting portion 11a is provided at each of the two acute corners (i.e., a pair) of the four corners of the base metal portion 11. In this embodiment, the blade mounting portion 11a has a triangular concave shape.

[0055] The mounting hole 11b penetrates the base metal portion 11 in the direction of the insert axis and opens into a pair of plate surfaces (front and back surfaces) of the base metal portion 11. The mounting hole 11b is a circular hole centered on the insert central axis C. A fastening member for fixing the cutting tool 10 to the insert mounting seat of the holder is inserted into the mounting hole 11b. Note that the mounting hole 11b is not required. In this case, the cutting tool 10 is fixed to the insert mounting seat by pressing the plate surface or outer surface of the cutting tool 10 with a fastening member such as a wedge member.

[0056] The blade portion 12 is fixed (joined) to the blade portion mounting portion 11a by a joining means such as brazing. The blade portion 12 is positioned at a predetermined corner among the multiple corners of the cutting tool 10. In the illustrated example, the blade portion 12 is provided at two acute corners (i.e., a pair) among the four corners of the cutting tool 10. However, the configuration is not limited to this; the base metal portion 11 may have only one blade portion mounting portion 11a, and only one blade portion 12 may be provided at this blade portion mounting portion 11a.

[0057] The blade portion 12 is composed of a cBN (cubic boron nitride) sintered body or a diamond sintered body (polycrystalline diamond, PCD). The cBN sintered body is a hard sintered body containing cBN and a binder. The diamond sintered body is a hard sintered body containing diamond and a binder. In other words, the blade portion 12 contains cubic boron nitride (cBN) or diamond.

[0058] When the blade portion 12 is made of a cBN sintered body, the cBN content of the blade portion 12 is, for example, 20% by volume or more and 80% by volume or less. Preferably, the cBN content of the blade portion 12 is 40% by volume or more. As a binder, a binder can be used that has a composition consisting of at least one selected from the group consisting of nitrides, carbides, borides, oxides and solid solutions thereof of elements of groups 4, 5, and 6 of the periodic table, and at least one selected from the group consisting of nitrides, borides, oxides and solid solutions thereof of aluminum. If the blade portion 12 is made of a diamond sintered body, the diamond content of the blade portion 12 is, for example, 80 volume percent or more.

[0059] The blade portion 12 is polygonal in shape, and in this embodiment, it is triangular in shape. As shown in Figure 2, the blade portion 12 has 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 chamfer honing 4 extending along the cutting edge 3, a projection 5, a vertical wall 6, and an inclined wall 7. In other words, the blade portion 12 has a rake face 1, a relief face 2, a cutting edge 3, a chamfer honing 4, a projection 5, a vertical wall 6, and an inclined wall 7. The cutting tool 10 is also equipped with the same components as the blade portion 12.

[0060] Figure 3 shows a plan view (top view) of the vicinity of the cutting edge 12 of the cutting tool 10, viewed from the insert axis direction. As shown in Figure 3, in a plan view with the rake face 1 facing forward, the cutting edge 3 has a V-shape. 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. More specifically, the corner edge 3a has a convex arc shape with a constant radius of curvature.

[0061] [Definition of direction] In this embodiment, an XYZ Cartesian coordinate system (3D Cartesian coordinate system) is appropriately set in each figure, and each component will be described. In a plan view of the vicinity of the cutting edge 12 of the cutting tool 10 shown in Figure 3, the direction in which the bisector B of the pair of straight blades 3b extends is called the front-to-back direction. 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 blade 3a is called the front side (-Y side), and the direction from the corner blade 3a toward the insert central axis C is called the rear side (+Y side).

[0062] Furthermore, in the plan view shown in Figure 3, 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 3, 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). Also, within the left-right direction, the direction approaching the bisector B is called the inside of the left-right direction (center side), and the direction moving away from the bisector B is called the outside of the left-right direction.

[0063] 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. That is, the up-down direction is the direction extending along the insert central axis C.

[0064] In this embodiment, the terms front, rear, left, right, top, and bottom are merely names (designations) 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.

[0065] Furthermore, the symbol O shown in Figure 3 represents the center O of the radius of curvature of the corner blade 3a. In the plan view shown in Figure 3, the direction connecting any point on the corner blade 3a to the center O is called the radial direction of the corner blade 3a or simply the radial direction. Of the radial directions of the corner blade 3a, the direction approaching the center O (the direction from the corner blade 3a toward the center O) is called the radially inward direction, and the direction moving away from the center O (the direction from the center O toward the corner blade 3a) is called the radially outward direction.

[0066] Furthermore, the direction in which the cutting edge 3 extends is called the blade length direction. Specifically, the blade length direction in which the corner cutting edge 3a extends is the curved direction along the corner cutting edge 3a (this is the direction in which the arc centered at the center O of the radius of curvature of the corner cutting edge 3a extends, and corresponds to the direction around center O). Also, the blade length direction in which the straight cutting edges 3b extend is the straight direction along each straight cutting edge 3b.

[0067] In this embodiment, the direction from the cutting edge 3 toward the rake face 1 in a plan view (the direction away from the cutting edge 3 toward the rake face 1) may be referred to as the inside of the rake face 1 or simply the inside. Also, the direction from the rake face 1 toward the cutting edge 3 in a plan view (the direction approaching the cutting edge 3 from the rake face 1) may be referred to as the outside of the rake face 1 or simply the outside.

[0068] In this embodiment, as shown in Figure 3, a virtual plane containing the bisector B and extending along the vertical direction is defined as the reference plane (symmetry plane) RP, and the blade portion 12 and the cutting tool 10 are left-right symmetrical (mirror symmetrical shape, mirror surface symmetrical shape). The reference plane RP is a vertical plane (YZ plane) that contains the bisector B and is perpendicular to the left-right direction (X-axis direction).

[0069] [Scooping surface] As shown in Figures 2, 3, 6, and 7, the rake face 1 is positioned on one of the pair of plate surfaces (front and back) of the blade portion 12, the one facing upward (front surface). The rake face 1 is positioned adjacent to the cutting edge 3, on the rear side and inward in the left-right direction. In this embodiment, the rake face 1 is positioned adjacent to the cutting edge 3, on the inward side in the insert diameter direction of the cutting edge 3. The rake face 1 has a first rake face 16 and a second rake face 17.

[0070] The first rake face 16 is the portion of the rake face 1 that is positioned closest to the cutting edge 3. In this embodiment, chamfer honing 4 is formed along the cutting edge 3, and the first rake face 16 is adjacent to the cutting edge 3 via the chamfer honing 4. In other words, the chamfer honing 4 is interposed between the first rake face 16 and the cutting edge 3. The first rake face 16 extends along the cutting edge 3 and, in the plan view shown in Figure 3, has a generally V-shape or a curved shape that is convex towards the front.

[0071] The first rake face 16 extends downward as it moves away from the cutting edge 3 in a direction perpendicular to the cutting edge 3 in the plan view of Figure 3. As shown in Figures 6 and 7, the first rake face 16 extends downward as it moves inward from the cutting edge 3 towards the inside of the rake face 1. Here, the symbol VS1 shown in Figure 7 represents a first virtual plane VS1 that extends in the vertical direction (Z-axis direction) and the direction perpendicular to it (XY plane direction). As shown in Figure 7, in a vertical cross-sectional view perpendicular to the cutting edge 3, the first rake face 16 is inclined at an angle θ1 with respect to the first virtual plane VS1, and in this embodiment, this angle θ1 is called the first rake angle θ1. The first rake face 16 is given a positive angle (conformal angle) first rake angle θ1.

[0072] The second rake face 17 is the portion of the rake face 1 located inside the first rake face 16. The second rake face 17 is located further away from the cutting edge 3 than the first rake face 16. The second rake face 17 is connected to the inner end of the first rake face 16. The second rake face 17 extends along the cutting edge 3 and, in the plan view shown in Figure 3, has an overall curved shape that is roughly V-shaped or convex towards the front.

[0073] The second rake face 17 extends downward as it moves away from the cutting edge 3 in a direction perpendicular to the cutting edge 3 in the plan view of Figure 3. As shown in Figures 6 and 7, the second rake face 17 extends downward as it moves inward from the connection portion 18 with the first rake face 16. As shown in Figure 7, in a vertical cross-sectional view perpendicular to the cutting edge 3, the second rake face 17 is inclined at an angle θ2 with respect to the first virtual plane VS1, and in this embodiment, this angle θ2 is called the second rake angle θ2. The second rake face 17 is given a positive angle (conformal angle) second rake angle θ2.

[0074] The second rake angle θ2, at which the second rake face 17 is inclined with respect to the first virtual plane VS1, is greater than the first rake angle θ1, at which the first rake face 16 is inclined with respect to the first virtual plane VS1. In this embodiment, the second rake angle θ2 is, for example, 20° or less.

[0075] In Figure 7, reference numeral 1a represents the lowest point 1a, which is located at the bottom of the rake face 1. The lowest point 1a is located at the inner end of the second rake face 17. Also, reference numeral 1b in Figure 7 represents the highest point 1b, which is located at the top of the rake face 1. The highest point 1b is located at the outer end of the first rake face 16.

[0076] As shown in Figure 7, in a vertical cross-sectional view along the vertical direction including the bisector B, the imaginary line passing through the lowest point 1a, which is the lowest point of the rake face 1, and the highest point 1b, which is the highest point of the rake face 1, is called the first imaginary line VL1. With respect to this first imaginary line VL1, the connection portion 18 between the first rake face 16 and the second rake face 17 protrudes upward. The connection portion 18 also extends along the cutting edge 3, and in the plan view shown in Figure 3, it has a roughly V-shape or a curved shape that is convex to the front. That is, the connection portion 18 has a ridge shape that extends along the cutting edge 3.

[0077] In the plan view of Figure 3, the distance D1 between the connection portion 18 between the first rake face 16 and the second rake face 17 and the cutting edge 3 is 0.3 mm or less. In other words, as shown in Figure 7, in a vertical cross-sectional view perpendicular to the cutting edge 3, the distance D1 corresponds to the distance between the cutting edge 3 and the connection portion 18 along the vertical and perpendicular directions (XY plane directions).

[0078] [Fleeing face] As shown in Figures 2, 4, and 5, the relief surface 2 is positioned on the outer circumferential surface of the blade portion 12, on the front and left-right outward-facing portions. The relief surface 2 is positioned below the cutting edge 3, adjacent to the cutting edge 3. The relief surface 2 extends in the circumferential direction of the insert. Specifically, the relief surface 2 extends across the corner blade 3a and the pair of straight blades 3b, that is, across the entire length of the cutting edge 3. In this embodiment, the relief surface 2 is a negative relief surface parallel to the insert's central axis C. However, it is not limited to this, and although not specifically shown, the relief surface 2 may extend inward in the radial direction of the insert as it moves downward from the cutting edge 3.

[0079] [Cutting edge] As shown in Figures 4 and 5, in this embodiment, the cutting edge 3 extends along the vertical direction and a direction perpendicular to it (XY plane direction). More specifically, the entire cutting edge 3 is contained within the XY plane (corresponding to the plane of the first virtual plane VS1). The cutting edge 3 has a corner blade 3a and a pair of straight blades 3b.

[0080] As shown in Figures 2 and 3, the corner blade 3a has a curved shape that is convex toward the front (-Y side), and in this embodiment, it has a circular arc shape that is convex toward the front. In the plan view shown in Figure 3, the radius of curvature of the corner blade 3a is, for example, 1.2 mm or less, and in this embodiment, it is about 0.8 mm.

[0081] A pair of straight blades 3b are connected to both ends of the corner blade 3a in the direction of its blade length, so as to be in smooth contact with each other. Specifically, each straight blade 3b extends linearly along each tangent line passing through both ends of the corner blade 3a. Each straight blade 3b extends outward in the left-right direction as it moves towards the rear (+Y side) from the connection point with the corner blade 3a.

[0082] The cutting tool 10 in this embodiment has an external shape that conforms to ISO standards, being a rhomboid insert with a vertex angle of 80°. Therefore, in the plan view of Figure 3, the opening angle (rhomboid cutting edge angle) α formed between the pair of straight blades 3b is set to 80°.

[0083] [Chamfer honing] The chamfer honing 4 is positioned adjacent to the cutting edge 3 on the rake face 1 side of the cutting edge 3. In the longitudinal section view of Figure 7, the chamfer honing 4 extends upward as it moves from the cutting edge 3 towards the inside of the rake face 1, along the direction in which the first virtual plane VS1 expands. In this longitudinal section view, the chamfer honing 4 is linear.

[0084] As shown in Figures 2 and 3, the portion of the chamfer honing 4 adjacent to the corner cutting edge 3a has a curved shape that is convex toward the front. Specifically, the portion of the chamfer honing 4 adjacent to the corner cutting edge 3a has a curved shape that is convex toward the front. In addition, the portions of the chamfer honing 4 adjacent to the pair of straight cutting edges 3b are each straight. The portions of the chamfer honing 4 adjacent to each straight cutting edge 3b extend toward the rear as they are directed outward in the left-right direction.

[0085] The honing width of the chamfer honing 4 (the width dimension of the chamfer honing 4 along the direction perpendicular to the cutting edge 3 in the plan view of Figure 3) is made small, for example, less than 0.05 mm. For this reason, the chamfer honing 4 can be said to substantially constitute a part of the cutting edge 3. In other words, the chamfer honing 4 is formed on the cutting edge 3, and more specifically, the chamfer honing 4 is formed on the corner cutting edge 3a and the pair of straight cutting edges 3b, respectively.

[0086] 〔protrusion〕 The projection 5 is positioned on the rake face 1 and protrudes from the rake face 1. Specifically, the projection 5 is rib-shaped and protrudes upward from the rake face 1, extending forward as it moves outward in the left-right direction. In this embodiment, the front end of the projection 5 is located on the second rake face 17. The front-rear dimension D2 between the front end of the corner blade 3a and the front end of the projection 5 is, for example, greater than 0.25 mm and less than 0.5 mm.

[0087] As shown in Figures 4 and 5, the inner and rear ends of the projection 5 in the left-right direction are positioned above the cutting edge 3. Also, as shown in Figure 7, the outer and front ends of the projection 5 in the left-right direction are positioned below the cutting edge 3. As shown in Figure 3, the projections 5 are provided in pairs in a mirror-image symmetry, with the reference plane RP, which is aligned vertically and contains the bisector B within the plane, as the plane of symmetry.

[0088] In the plan view shown in Figure 3, the projection 5 has a projection ridge 51 that extends forward as it moves away from the bisector B in the left-right direction, a first inclined surface 52 that is positioned between the projection ridge 51 and the bisector B in this plan view and extends downward as it moves away from the projection ridge 51, and a second inclined surface 53 that is positioned on the opposite side of the projection ridge 51 from the bisector B (i.e., outward in the left-right direction) in this plan view and extends downward as it moves away from the projection ridge 51.

[0089] The protruding ridge line 51 extends downward as it moves away from the bisector B in the plan view of Figure 3 (see Figure 2). The protruding ridge line 51 also extends in a straight line. In this embodiment, the angle at which the protruding ridge line 51 is inclined with respect to the first virtual plane VS1 perpendicular to the vertical direction is, for example, about 12°. In the plan view of Figure 3, the projection angle β formed between the bisector B and the protruding ridge line 51 is, for example, greater than 10° and less than or equal to 45°.

[0090] In the plan view of Figure 3, the extension of the projection ridge 51 extending outward and forward in the left-right direction intersects with the corner blade 3a. Also, the inner and rear end of the projection ridge 51 in the left-right direction is located on the bisector B (reference plane RP). In this embodiment, the inner and rear end of the projection ridge 51 in the left-right direction (i.e., the intersection of the projection ridge 51 and the bisector B) is located behind the center O of the radius of curvature of the corner blade 3a.

[0091] The first inclined surface 52 is connected to the projection ridge 51. In the plan view of Figure 3, the first inclined surface 52 extends downward as it moves away from the projection ridge 51 in a direction perpendicular to the direction in which the projection ridge 51 extends. In this embodiment, the first inclined surface 52 is triangular in shape. The first inclined surface 52 is also planar in shape.

[0092] In the plan view shown in Figure 3, the inner ends of the first inclined surface 52 in the left-right direction are located on the bisector B (reference plane RP). That is, in this plan view, the first inclined surface 52 extends to the bisector B. More specifically, one of the three sides of the triangular first inclined surface 52 extends along the bisector B (coinciding with the bisector B). Also, the center O is located on the aforementioned side of the first inclined surface 52. For this reason, the pair of projections 5 are connected to each other via the aforementioned side of each first inclined surface 52.

[0093] The second inclined surface 53 is connected to the protruding ridge line 51. In the plan view of Figure 3, the second inclined surface 53 extends downward as it moves away from the protruding ridge line 51 in a direction perpendicular to the direction in which the protruding ridge line 51 extends. In this embodiment, the second inclined surface 53 has a substantially triangular shape. The second inclined surface 53 also has a planar shape.

[0094] In the plan view shown in Figure 3, the width dimension (maximum width dimension) of the first inclined surface 52 along the direction perpendicular to the protruding ridge line 51 is larger than the width dimension (maximum width dimension) of the second inclined surface 53 along the direction perpendicular to the protruding ridge line 51.

[0095] Here, in Figures 3 and 9, the virtual plane (vertical section) that includes the protruding ridge line 51 within the plane and runs along the vertical direction is called the second virtual plane VS2. The virtual plane that includes the protruding ridge line 51 within the plane and is perpendicular to the second virtual plane VS2 is called the third virtual plane VS3. Figure 9 shows a cross-sectional view perpendicular to the protruding ridge line 51. In the cross-sectional view shown in Figure 9, the first inclination angle θ11 formed between the third virtual plane VS3 and the first inclined surface 52 is larger than the second inclination angle θ12 formed between the third virtual plane VS3 and the second inclined surface 53.

[0096] [Vertical wall] As shown in Figures 2 and 3, the vertical wall 6 is positioned on the opposite side of the rake face 1 from the cutting edge 3 (i.e., on the inside of the rake face 1). The vertical wall 6 is a wall surface facing forward. The vertical wall 6 is located behind the cutting edge 3, the rake face 1, and the projection 5. Also, as shown in Figures 4 to 7, the vertical wall 6 protrudes above the cutting edge 3, the rake face 1, and the projection 5. The upper end of the vertical wall 6 is connected to the upper surface 12a of the blade portion 12. As shown in Figure 3, the vertical walls 6 are provided in pairs in a mirror-image symmetry, with the reference plane RP, which is aligned vertically and contains the bisector B within the plane, as the plane of symmetry.

[0097] As shown in Figures 2 and 3, the vertical wall 6 has a lower wall surface 61 connected to the rake face 1 and extending upward from the connection point with the rake face 1 toward the rear, and an upper wall surface 62 connected to the upper end of the lower wall surface 61 and extending upward from the connection point with the lower wall surface 61 toward the rear. In other words, the upper wall surface 62 is located above the lower wall surface 61. As shown in Figure 7, the upper wall surface 62 is located above the cutting edge 3.

[0098] As shown in Figures 2 and 3, the lower wall surface 61 has a lower inner wall surface 61a located in the inner portion in the left-right direction of the lower wall surface 61, and a lower outer wall surface 61b located in the outer portion in the left-right direction of the lower wall surface 61. The lower inner wall surface 61a and the lower outer wall surface 61b are both planar.

[0099] The lower inner wall surface 61a extends towards the rear as it moves inward in the left-right direction. The inner end of the lower inner wall surface 61a in the left-right direction is connected to the second inclined surface 53 of the projection 5. The outer end of the lower inner wall surface 61a in the left-right direction is connected to the inner end of the lower outer wall surface 61b in the left-right direction. The lower outer wall surface 61b extends towards the rear as it moves outward in the left-right direction.

[0100] The connection between the lower inner wall surface 61a and the lower outer wall surface 61b forms a ridge that is convex toward the front. The connection between the lower inner wall surface 61a and the lower outer wall surface 61b (ridge) extends upward and inward in the left-right direction as it approaches the rear.

[0101] The upper wall surface 62 has an upper inner wall surface 62a located in the inner portion in the left-right direction of the upper wall surface 62, and an upper outer wall surface 62b located in the outer portion in the left-right direction of the upper wall surface 62. The upper inner wall surface 62a and the upper outer wall surface 62b are each planar. The lower end of the upper inner wall surface 62a is connected to the upper end of the lower inner wall surface 61a. The lower end of the upper outer wall surface 62b is connected to the upper end of the lower outer wall surface 61b.

[0102] The upper inner wall surface 62a extends towards the rear as it moves inward in the left-right direction. The inner ends of the upper inner wall surface 62a in the left-right direction are located on the reference plane RP (bisector B). Therefore, the upper inner wall surfaces 62a of the pair of vertical walls 6 are connected to each other on the reference plane RP. The connection portion between the upper inner wall surfaces 62a of the pair of vertical walls 6 forms a valley shape (a valley shape with a concave V-shaped cross-section) that is concave towards the rear. The aforementioned connection portion (valley line) extends upward as it moves towards the rear.

[0103] The left-right outer end of the upper inner wall surface 62a is connected to the left-right inner end of the upper outer wall surface 62b. The upper outer wall surface 62b extends towards the rear as it moves outward in the left-right direction.

[0104] The connection between the upper inner wall surface 62a and the upper outer wall surface 62b forms a ridge that is convex toward the front. The connection between the upper inner wall surface 62a and the upper outer wall surface 62b (ridge) extends toward the rear, both upward and inward in the left-right direction.

[0105] In the vertical cross-sectional view shown in Figure 7 (a vertical cross-sectional view along the vertical direction including the bisector B), the imaginary straight line passing through the upper front end 13 where the upper surface 12a of the blade portion 12 and the vertical wall 6 are connected, and the lowest point 1a of the rake face 1, is called the second imaginary straight line VL2. With respect to this second imaginary straight line VL2, the connection portion between the upper wall surface 62 and the lower wall surface 61 is recessed on the lower side. The reference numeral 62c shown in Figure 7 represents the lower end portion 62c of the upper wall surface 62 (the connection portion with the projection 5), and the "connection portion between the upper wall surface 62 and the lower wall surface 61" corresponds to the vicinity of this lower end portion 62c.

[0106] Figure 8 is a longitudinal cross-sectional view showing the section VIII-VIII in Figure 3. Figure 8 shows a longitudinal cross-sectional view along the vertical direction passing through the vertical wall 6, the rake face 1, and the cutting edge 3. More specifically, Figure 8 is a longitudinal cross-sectional view passing through the vicinity of the connection point (ridge) between the upper inner wall surface 62a and the upper outer wall surface 62b, the vicinity of the connection point (ridge) between the lower inner wall surface 61a and the lower outer wall surface 61b, and the vicinity of the connection point between the corner edge 3a and the straight edge 3b.

[0107] As shown in Figure 8, in a vertical cross-sectional view along the vertical direction passing through the vertical wall 6, the rake face 1, and the cutting edge 3, the upper inclination angle θ22 of the upper wall surface 62 with respect to the first virtual plane VS1 is greater than the lower inclination angle θ21 of the lower wall surface 61 with respect to the first virtual plane VS1 which is perpendicular to the vertical direction. In the illustrated example, the upper inclination angle θ22 is set to more than twice the lower inclination angle θ21. In this embodiment, the upper inclination angle θ22 is set to, for example, 60° or less.

[0108] In Figure 8, the virtual circle indicated by the symbol IC represents an inscribed circle IC that is tangent to the three sides of the rake face 1, the lower wall surface 61, and the upper wall surface 62. In this embodiment, the diameter dimension d of the inscribed circle IC is, for example, greater than 0.5 mm and less than 1.0 mm.

[0109] [Slanted wall] As shown in Figures 2 to 6, the inclined wall 7 is positioned on the outer and rear sides of the vertical wall 6 in the left-right direction. In the plan view shown in Figure 3, the inclined wall 7 extends upward as it approaches the bisector B in a direction perpendicular to the straight blade 3b. As shown in Figure 3, the inclined walls 7 are provided in pairs in a mirror-image symmetry, with the reference plane RP, which is aligned vertically and contains the bisector B within the plane, as the plane of symmetry.

[0110] In Figures 2 to 6, the symbol VS4 represents a fourth virtual plane VS4 that contains the chamfer honing 4 adjacent to the straight blade 3b within its plane. The inclined wall 7 is formed approximately parallel to the fourth virtual plane VS4 and is located below the fourth virtual plane VS4. In this embodiment, the inclined wall 7 is positioned below the fourth virtual plane VS4 by, for example, about 0.1 mm.

[0111] The inclined wall 7 has a plurality of wall grooves 71 that extend parallel to the straight blade 3b. In the plan view shown in Figure 3, the plurality of wall grooves 71 are spaced apart from each other in a direction perpendicular to the straight blade 3b. As shown in Figures 4 and 6, in this embodiment, the plurality of wall grooves 71 are arranged at equal pitches along the inclination direction of the inclined wall 7.

[0112] [Effects of this embodiment] In the cutting tool 10 of this embodiment described above, a projection 5 is provided on the rake face 1 of the blade portion 12, and the projection ridge line 51 of this projection 5 extends at an inclination with respect to the bisector B in a plan view when the rake face 1 is viewed from the front. Specifically, the projection ridge line 51 extends forward as it moves away from the bisector B in the left-right direction in a plan view.

[0113] Furthermore, the projection 5 has a first inclined surface 52 and a second inclined surface 53 positioned on both sides of the projection ridge line 51. The first inclined surface 52 is an inclined surface located on the lower side as it moves away from the projection ridge line 51 toward the bisector B, and the second inclined surface 53 is an inclined surface located on the lower side as it moves away from the projection ridge line 51 toward the opposite side of the bisector B.

[0114] Here, Figure 10 is a diagram illustrating the function of the first inclined surface 52 and the second inclined surface 53 of the projection 5, schematically representing the vicinity of the cutting edge 12 during turning. In Figure 10, the symbol WP represents the workpiece WP, the symbol F represents the tool feed direction F, and the symbols CF1 and CF2 represent the directions in which the chips generated at the cutting edge 3 flow.

[0115] In this embodiment, in the finishing machining area shown in Figure 12, when the depth of cut (ap) and feed rate (fr) are large, for example, ap = 0.3 mm and fr = 0.3 mm / rev, as shown by arrow CF1 in Figure 10, the chips generated from the cutting edge 3 by cutting come into contact with the first inclined surface 52 and are discharged toward the side of the bisecting line B of the projection 5 (corresponding to the tool feed direction F). As a result, the chips are strongly strained and curled under resistance, and are discharged in the direction of machining (tool feed direction F). The strongly strained and curled chips are finely divided at approximately constant intervals and processed stably.

[0116] Furthermore, in the finishing machining area shown in Figure 12, when the depth of cut (ap) and feed rate (fr) are small, for example, ap = 0.1 mm or less and fr = 0.1 mm / rev or less, the chips generated from the cutting edge 3 by cutting come into contact with the second inclined surface 53 and are discharged in the opposite direction to the bisector B of the projection 5 (corresponding to the opposite direction to the tool feed direction F), as shown by arrow CF2 in Figure 10. As a result, the chips are less susceptible to resistance and load, and the chip discharge rate is maintained at a high level. Because such chips have a high discharge rate, they are less likely to accumulate near the machined surface of the workpiece WP and are discharged outside the machining area. Therefore, it is possible to suppress problems such as thin, elongated chips getting tangled in the workpiece WP, parts of the machine tool (chuck), tools, etc.

[0117] As described above, according to this embodiment, appropriate chip removal can be achieved by using different inclined surfaces (first inclined surface 52, second inclined surface 53) that act on the chips depending on the machining conditions (depending on whether it is high depth of cut or low depth of cut). Therefore, the chip removal performance in the finishing machining area can be stably improved. In addition, it is possible to prevent the shutdown of production equipment due to chip entanglement with the workpiece or tools, thereby improving production efficiency (machining efficiency). In this embodiment, in the finishing area shown in Figure 12, as indicated by the circled number 2, when the depth of cut (ap) and feed rate (fr) are, for example, ap = 0.15 mm and fr = 0.15 mm / rev, the chips flow out toward the protruding ridge line 51. In this case, the chips may come into contact with either the first inclined surface 52 or the second inclined surface 53.

[0118] Furthermore, the rake face 1 extends downwards as it moves inward (away from the cutting edge 3 towards the rake face 1 in a plan view). As a result, the cutting edge 3 is given a positive rake angle, which enhances cutting performance. This reduces the constraint on chips and lowers the load on the cutting edge.

[0119] Furthermore, the rake face 1 has a first rake face 16 adjacent to the cutting edge 3, and a second rake face 17 positioned inside the first rake face 16, with a larger rake angle than the first rake face 16. Therefore, even if rake face wear occurs on the first rake face 16 as machining progresses, chips that enter the worn rake face can be stably flowed towards the second rake face 17 without clogging. This suppresses chip clogging due to rake face wear and enables stable cutting.

[0120] Specifically, unlike this embodiment, in the case of conventional products where the rake face 1 does not have a stepped rake angle as shown in Figure 11(a), if rake face wear FW occurs, the chips CH that enter the rake face wear FW can clog, causing the cutting edge to be subjected to a strong load and potentially leading to cutting edge chipping. On the other hand, in this embodiment, as shown in Figure 11(b), the chips CH that enter the rake face wear FW are directed toward the second rake face 17, thus suppressing cutting edge chipping due to chip clogging. In particular, tool life can be extended even under machining conditions with high depth of cut and feed rate, and high cutting load (such as at high depth of cut).

[0121] Based on the above, according to this embodiment, excellent chip evacuation performance can be obtained and cutting edge chipping can be suppressed during turning operations such as finishing.

[0122] In this embodiment, the protruding ridge line 51 extends downward as it moves away from the bisector B in a plan view.

[0123] In this case, the projection ridge 51, which is the top of the projection 5, extends downward as it approaches the outside of the rake face 1 (in the direction from the rake face 1 towards the cutting edge 3 in a plan view). As a result, the chips generated by the cutting edge 3 and directed toward the inside of the rake face 1 can more easily and stably come into contact with each part of the projection 5 (first inclined surface 52, second inclined surface 53, projection ridge 51). Therefore, the effects of this embodiment described above are more stably achieved.

[0124] In this embodiment, the protruding ridge line 51 extends in a straight line. In the above configuration, since the projection ridge 51 is straight, the differentiation between the first inclined surface 52 and the second inclined surface 53 can be made more stable compared to the case of projection ridges that are curved or bent, for example. In other words, the effect of improving chip processing performance is more stable. In addition, since inflection points are not formed on the projection ridge 51, localized loads are suppressed, and damage to the projection 5 can be prevented. The effect (function) of the projection 5 is maintained well over a long period of time.

[0125] In this embodiment, in a plan view, the projection angle β formed between the bisector B and the projection ridge 51 is greater than 10° and less than or equal to 45°.

[0126] When the projection angle β exceeds 10°, the chip can be stably brought into contact with the first inclined surface 52, such as during high cutting depths. Also, when the projection angle β is 45° or less, the chip can be stably brought into contact with the second inclined surface 53, such as during low cutting depths.

[0127] Furthermore, in this embodiment, as shown in Figure 9, in a cross-sectional view perpendicular to the protruding ridge line 51, the first inclination angle θ11 formed between the third virtual plane VS3 and the first inclined surface 52 is greater than the second inclination angle θ12 formed between the third virtual plane VS3 and the second inclined surface 53.

[0128] In this case, the first inclination angle θ11 is greater than the second inclination angle θ12, meaning the inclination of the first inclined surface 52 is steep. Therefore, the first inclined surface 52 acts strongly on the chips generated during high-depth cutting. As a result, the chips can be more easily broken up during high-depth cutting.

[0129] Furthermore, since the second inclination angle θ12 is smaller than the first inclination angle θ11, meaning the inclination of the second inclined surface 53 is gentle, when chips generated during low depth of cut contact the second inclined surface 53, the chip outflow velocity is maintained at a high level. As a result, chip handling performance is more stably improved during low depth of cut.

[0130] In this embodiment, the second rake angle θ2 in Figure 7 is 20° or less. By keeping the second rake angle θ2 below 20°, the cutting edge angle of the cutting edge 3 is sufficiently secured. The strength of the cutting edge is well maintained, and chipping of the cutting edge can be reliably suppressed.

[0131] Furthermore, in this embodiment, in the plan view of Figure 3, the distance D1 between the connection portion 18 between the first rake face 16 and the second rake face 17 and the cutting edge 3 is 0.3 mm or less.

[0132] Because the above-mentioned distance D1 is 0.3 mm or less, even if chips enter the rake face wear on the first rake face 16, these chips do not clog and flow stably to the second rake face 17. Therefore, the function of suppressing cutting edge chipping by the second rake face 17 is obtained more stably.

[0133] Furthermore, in this embodiment, as shown in Figure 7, in a vertical cross-sectional view along the vertical direction including the bisector B, the connection portion 18 between the first rake face 16 and the second rake face 17 protrudes upward with respect to the first virtual straight line VL1 passing through the lowest point 1a, which is the lowest point of the rake face 1, and the highest point 1b, which is the highest point of the rake face 1. The connection portion between the upper wall surface 62 and the lower wall surface 61 (corresponding to the vicinity of the lower end portion 62c in Figure 7) is recessed downward with respect to the second virtual straight line VL2 passing through the upper front end 13, where the upper surface 12a of the blade portion 12 is connected to the vertical wall 6, and the lowest point 1a of the rake face 1.

[0134] In the above-mentioned vertical cross-sectional view, the connection portion 18 between the first rake face 16 and the second rake face 17 protrudes upward with respect to the first virtual straight line VL1, thereby stably obtaining the above-mentioned effects of the two-stage rake face of this embodiment.

[0135] Furthermore, in the above-mentioned vertical cross-sectional view, the connection between the upper wall surface 62 and the lower wall surface 61 is recessed on the lower side with respect to the second virtual straight line VL2, allowing chips to come into contact with the vertical wall 6 at multiple points (upper wall surface 62, lower wall surface 61). This allows the force received from the chips to be distributed to multiple points, suppressing wear and damage near the vertical wall 6.

[0136] Furthermore, in this embodiment, as shown in Figure 8, in a vertical cross-sectional view along the vertical direction passing through the vertical wall 6, the rake face 1, and the cutting edge 3, the upper inclination angle θ22 of the upper wall 62 with respect to the first virtual plane VS1 is larger than the lower inclination angle θ21 of the lower wall 61 with respect to the first virtual plane VS1. The diameter dimension d of the inscribed circle IC tangent to the three sides of the rake face 1, the lower wall 61, and the upper wall 62 is less than 1.0 mm.

[0137] In the above configuration, the upper inclination angle θ22 is larger than the lower inclination angle θ21 (the angle is steeper), so that the chips can stably come into contact with the upper wall surface 62. This stably improves chip handling performance, especially at high depths of cut.

[0138] Furthermore, by having a diameter dimension d of the inscribed circle IC less than 1.0 mm, the chips can be stably restrained, resulting in chips that are less prone to stretching and have a curling tendency.

[0139] In this embodiment, the upward tilt angle θ22 is 60° or less. By keeping the upper inclination angle θ22 to 60° or less, chip clogging on the upper wall surface 62 is less likely to occur, and the increase in cutting edge load is suppressed.

[0140] Furthermore, in this embodiment, in the plan view of Figure 3, the first inclined surface 52 extends to the bisector B.

[0141] In this case, the surface area of ​​the first inclined surface 52 can be made large. When cutting at a high depth of cut, the wide chips generated from the cutting edge 3 can be stably brought into contact with the first inclined surface 52. The first inclined surface 52 allows for stable processing of the chips.

[0142] In this embodiment, the blade portion 12, in plan view, has an inclined wall 7 that extends upward as it approaches the bisector B in a direction perpendicular to the straight blade 3b, the straight blade 3b has chamfered honing 4 formed on it, the inclined wall 7 is located below the fourth virtual plane VS4 that contains the chamfered honing 4 in its plane, and the inclined wall 7 has a plurality of wall grooves 71 that extend parallel to the straight blade 3b.

[0143] In this case, the chip comes into contact with the groove 71 in the inclined wall 7, causing the inclined wall 7 to function as a derivative (secondary) cutting edge. This improves chip breaking performance.

[0144] In this embodiment, the dimension D2 in the front-rear direction between the front end of the corner blade 3a and the front end of the projection 5 is greater than 0.25 mm and less than 0.5 mm.

[0145] If the dimension D2 in the front-rear direction between the front end of the corner blade 3a and the front end of the projection 5 exceeds 0.25 mm, the obstruction of the flow of chips from the first rake face 16 to the second rake face 17 by the projection 5 is suppressed, and chip processing performance is stably improved. Also, if the dimension D2 in the front-rear direction between the front end of the corner blade 3a and the front end of the projection 5 is less than 0.5 mm, the chips will stably contact the projection 5, and chip processing performance will be stably improved.

[0146] In this embodiment, the blade portion 12 is symmetrical, with a virtual plane RP that includes the bisector B and lies along the vertical direction serving as the reference plane.

[0147] In the above configuration, the cutting edge 12 has a left-right symmetrical shape (mirror symmetrical shape, mirror surface symmetrical shape) with respect to the reference plane (symmetrical plane) RP. Therefore, the cutting tool 10 can be used as a bi-handed tool (left-handed and right-handed) without any particular restrictions on the tool feed direction during turning. This increases the degree of freedom in the cutting conditions to which the cutting tool 10 can be applied.

[0148] Furthermore, since a pair of protrusions 5 are provided on the rake face 1, especially when cutting at high depths, chips that come into contact with the first inclined surface 52 of one of the protrusions 5 closest to the machined surface of the workpiece are then brought into contact with the other protrusion 5. This further improves chip removal efficiency. In addition, especially when cutting at high depths, chips are brought into stable contact with the pair of vertical walls 6, which also improves chip removal efficiency.

[0149] In this embodiment, the blade portion 12 contains cubic boron nitride (cBN) or diamond. That is, the blade portion 12 is composed of a cBN sintered body or a diamond sintered body. In this case, the hardness of the blade portion 12 is sufficiently increased, which suppresses wear and damage to the components of the blade portion 12, such as the cutting edge 3, projection 5, and vertical wall 6, allowing the desired turning process to be performed stably over a long period of time.

[0150] [Other components included in the present invention] 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.

[0151] In the embodiments described above, an example was given in which the inclined wall 7 has a plurality of wall grooves 71 extending parallel to the straight blade 3b, but it is not limited to this. As shown in Figure 10, the inclined wall 7 may have a configuration without wall grooves 71. In this case, the inclined wall 7 may be formed integrally with the chamfer honing 4 adjacent to the straight blade 3b by a single plane, for example.

[0152] In the above-described embodiment, an example was given in which the corner edge 3a of the cutting edge 3 is in the shape of a convex arc with a constant radius of curvature, but it is not limited to this. Although not specifically shown, the corner edge 3a may be formed in the shape of a convex curve by combining, for example, multiple arcs having different radii of curvature.

[0153] Furthermore, in the above-described embodiment, the cutting tool 10 is a rhombic insert with a vertex angle of 80° conforming to ISO standards, and in the plan view of Figure 3, the opening angle (rhombic angle at the cutting edge) α formed between the pair of straight blades 3b is set to 80°. However, the invention is not limited to this. The cutting tool may be a rhombic insert conforming to ISO standards, for example, with an opening angle α of 35° or 55°.

[0154] Furthermore, in the embodiments described above, examples were given in which the blade portion 12 and the cutting tool 10 are symmetrical (mirror-image symmetrical, mirror-surface symmetrical) with respect to a reference plane (symmetrical plane) RP that includes the bisector B and is aligned in the vertical direction, but the invention is not limited to this. That is, the cutting tool 10 is not limited to a tool for both left-handed and right-handed use, but may be, for example, a tool for left-handed use only or a tool for right-handed use only. Specifically, the blade portion 12 and the cutting tool 10 may be asymmetrical with respect to the reference plane RP.

[0155] 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]

[0156] The cutting tool of the present invention provides excellent chip evacuation and suppresses cutting edge chipping during turning operations such as finishing. Therefore, it has industrial applicability. [Explanation of Symbols]

[0157] 1... Scoop surface 1a...Lowest point 1b...Highest point 2…Escape 3…Cutting edge 3a...Corner blade 3b…Straight blade 4. Chamfering 5…Protrusion 6…Vertical wall 7…Slanted wall 10…Cutting tools 12...Blade part 12a…Top surface 13…Top front edge 16...First scoop face 17...Second scoop face 18...Connection part 51…Protruding ridge 52...First slope 53…Second slope 61…Lower wall surface 62… Upper wall surface 71…Wall groove B…Bisector d... Diameter of the inscribed circle D1... Distance D2... Dimensions IC...Inscribed circle RP…Reference plane VL1…First virtual line VL2…Second virtual line VS1…First virtual plane VS2…Second virtual plane VS3…Third virtual plane VS4…Fourth virtual plane β…Protrusion angle θ1…First rake angle θ2…Second rake angle θ11…first inclination angle θ12…Second inclination angle θ21…Lower inclination angle θ22…Upper inclination angle

Claims

1. Equipped with a blade containing cubic boron nitride or diamond, The aforementioned blade portion is 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 scoop surface is provided with a projection that is positioned on the scoop surface and protrudes from the scoop surface, 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, In the aforementioned plan view, the direction in which the bisectors of the pair of straight blades extend is defined as the front-to-back direction, the direction perpendicular to the bisectors 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 protrusion is In the aforementioned plan view, the protruding ridges extend forward as they move away from the bisector in the left-right direction, In the plan view, a first inclined surface is positioned between the protruding ridge and the bisector, and extends downward as it moves away from the protruding ridge, In the plan view, the second inclined surface is located on the opposite side of the bisector of the protruding ridge and extends downward as it moves away from the protruding ridge, The aforementioned scoop surface is, A first rake face extending downward from the cutting edge toward the inside of the rake face, It has a second rake face positioned inside the first rake face and extending downward inward from the connection portion with the first rake face, The second rake angle at which the second rake face is inclined with respect to the first virtual plane is greater than the first rake angle at which the first rake face is inclined with respect to the first virtual plane that extends vertically and perpendicularly. cutting tools.

2. The aforementioned protruding ridge extends downward as it moves away from the bisector in the plan view. The cutting tool according to claim 1.

3. The aforementioned protruding ridge extends in a straight line. A cutting tool according to claim 1 or 2.

4. In the aforementioned plan view, the angle of the projection formed between the bisector and the projection ridge is greater than 10° and less than or equal to 45°. A cutting tool according to claim 1 or 2.

5. The virtual plane that includes the aforementioned protruding ridge line within the plane and lies along the vertical direction is defined as the second virtual plane. A third virtual plane is defined as a virtual plane that includes the aforementioned protruding ridge line within the plane and is perpendicular to the second virtual plane. In a cross-sectional view perpendicular to the aforementioned protruding ridge, the first inclination angle formed between the third virtual plane and the first inclined surface is greater than the second inclination angle formed between the third virtual plane and the second inclined surface. A cutting tool according to claim 1 or 2.

6. The second rake angle is 20° or less. A cutting tool according to claim 1 or 2.

7. In the plan view, the distance between the connection portion between the first rake face and the second rake face and the cutting edge is 0.3 mm or less. A cutting tool according to claim 1 or 2.

8. The blade portion is provided with a vertical wall that is positioned on the opposite side of the cutting edge of the rake surface and faces forward, The aforementioned vertical wall is, A lower wall surface connected to the scoop surface, extending upward from the connection point with the scoop surface toward the rear, It has an upper wall surface connected to the upper end of the lower wall surface and extending upward from the connection portion with the lower wall surface toward the rear, In a vertical cross-sectional view along the vertical direction including the aforementioned bisector, With respect to a first imaginary straight line passing through the lowest point of the rake face and the highest point of the rake face, the connection portion between the first rake face and the second rake face protrudes upward. With respect to a second imaginary straight line passing through the upper front end where the upper surface of the blade portion and the vertical wall are connected, and the lowest point, the connection portion between the upper wall surface and the lower wall surface is recessed downwards. A cutting tool according to claim 1 or 2.

9. The blade portion is provided with a vertical wall that is positioned on the opposite side of the cutting edge of the rake surface and faces forward, The aforementioned vertical wall is, A lower wall surface connected to the scoop surface, extending upward from the connection point with the scoop surface toward the rear, It has an upper wall surface connected to the upper end of the lower wall surface and extending upward from the connection portion with the lower wall surface toward the rear, In a vertical cross-sectional view along the vertical direction passing through the vertical wall, the rake face, and the cutting edge, The upward inclination angle of the upper wall surface relative to the first virtual plane is greater than the downward inclination angle of the lower wall surface relative to the first virtual plane. The diameter of the inscribed circle tangent to the three sides of the scoop face, the lower wall surface, and the upper wall surface is less than 1.0 mm. A cutting tool according to claim 1 or 2.

10. The aforementioned upward tilt angle is 60° or less. The cutting tool according to claim 9.

11. In the aforementioned plan view, the first inclined surface extends to the line of the bisector. A cutting tool according to claim 1 or 2.

12. The blade portion, in plan view, has an inclined wall that extends upward as it approaches the bisector in a direction perpendicular to the straight blade, The aforementioned straight blade has chamfer honing formed on it. The inclined wall is located below the fourth virtual plane that includes the chamfer honing in its plane, The inclined wall has a plurality of wall grooves extending parallel to the straight blade. A cutting tool according to claim 1 or 2.

13. The dimension in the front-rear direction between the front end of the corner blade and the front end of the projection is greater than 0.25 mm and less than 0.5 mm. A cutting tool according to claim 1 or 2.

14. With a virtual plane that includes the aforementioned bisector and extends along the vertical direction as the reference plane, the blade portion is symmetrical. A cutting tool according to claim 1 or 2.

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