Cutting insert and cutting tool including same

Abstract

To alleviate or eliminate angle restrictions during inclined machining while achieving both a design in which the abutment surface of an insert and the ridgeline of a main cutting edge are arranged in a twisted manner while keeping the abutment surface at a clearance angle of zero degree, and a predetermined arrangement relationship between a minor cutting edge and the abutment surface of an insert. [Solution] The abutment surface of the cutting insert 10 is arranged perpendicular to the upper and lower surfaces, and when viewed from the top side perpendicular to the lower surface, the abutment surface 40 has at least a linear first portion 41A, and when viewed from the top, the minor cutting edge 22 has at least a linear second portion 22B, and when viewed from the top, the linear first portion 41A of the abutment surface 40 is arranged at a different angle to the linear second portion 22B of the minor cutting edge 22, and when the first portion 41A is used as a reference, the second portion 22B has an angle that changes in a direction that reduces the internal angle with a virtual straight line 21VL that extends and approximates the major cutting edge.

Description

[Technical Field]

[0001] The present invention relates to a cutting insert and a cutting tool including the same. [Background technology]

[0002] When performing high-feed machining of workpieces such as metals using a cutting tool equipped with cutting inserts, double-sided inserts for high-feed machining, designed from the perspective of securely fixing the insert and being economical, are sometimes used (see, for example, Patent Document 1). In such double-sided inserts, the insert abutment surface (restraint surface) below the minor cutting edge tends to be parallel to the insert center axis, and the insert abutment surface and the minor cutting edge tend to be positioned so as to overlap when viewed from above the insert.

[0003] On the other hand, the maximum depth of cut, length of the main cutting edge, and cutting edge angle of the cutting insert are important factors that determine tool performance. One example of ensuring these is to design the insert's contact surface and the ridgeline of the main cutting edge in a twisted arrangement (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5967330 [Patent Document 2] International Publication No. 2021 / 246321 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if one were to maintain the positional relationship between the minor cutting edge and the insert abutment surface as in Patent Document 2 while adopting such a design, the length of the minor cutting edge would become shorter, which would result in a problem of greater angle restrictions during inclined machining, making it difficult to achieve both this design and positional relationship.On the other hand, with a cutting insert such as that in Patent Document 1, the abutment surface is determined by the shape of the cutting edge and there is no degree of freedom, so if a more versatile and flexible structure could be achieved while setting the abutment surface to a clearance angle of zero degrees (parallel to the insert center axis), ease of use would be improved.

[0006] Therefore, the present invention aims to provide a cutting insert and a cutting tool equipped with the same that can relax or eliminate angle restrictions during inclined machining while maintaining a design in which the abutment surface of the insert and the ridge of the main cutting edge are arranged in a twisted position while keeping the abutment surface with a clearance angle of zero degrees, and while maintaining a predetermined positional relationship between the minor cutting edge and the insert abutment surface. [Means for solving the problem]

[0007] One aspect of the present invention is a cutting insert for use in a cutting tool, comprising: a top surface serving as a first end surface; a lower surface serving as a second end surface, which is the surface opposite to the upper surface; a peripheral side surface formed to connect the upper surface and the lower surface; a major cutting edge and a minor cutting edge formed in at least a part of an intersection region between the upper surface and the peripheral side surface and an intersection region between the lower surface and the peripheral side surface, respectively; a contact surface formed on the peripheral side surface; At least two clearance faces located above and below the contact face; Equipped with The contact surfaces are arranged perpendicular to the upper and lower surfaces, When viewed from above perpendicularly to the lower surface, the contact surface has at least a linear first portion, When viewed from above, the minor cutting edge has at least a linear second portion, When viewed from above, the linear first portion of the contact surface is arranged at a different angle from the linear second portion of the minor cutting edge, When the first portion is taken as a reference, the second portion is a cutting insert in which the angle of the second portion differs in a direction in which the internal angle with respect to an imaginary line that approximates and extends the main cutting edge becomes smaller.

[0008] This cutting insert was conceived to achieve both a design and a positional relationship, taking into consideration the problem that maintaining the positional relationship between the minor cutting edge and the abutment surface shortens the length of the minor cutting edge and increases the angle restriction during inclined machining.The angle between the linear first portion of the abutment surface and the linear second portion of the minor cutting edge in a top view is different in a direction that reduces the internal angle between the second portion and a virtual line that approximates and extends the major cutting edge when the first portion is used as the reference, making it possible to lengthen the minor cutting edge while achieving reliable insert abutment.By making the minor cutting edge of this cutting insert longer, it is possible to alleviate or eliminate the angle restriction during inclined machining even in an arrangement design in which the insert abutment surface and the major cutting edge are twisted.

[0009] In the cutting insert as described above, an extension line of the major cutting edge and an extension line of the minor cutting edge may intersect at an interior obtuse angle when viewed from above.

[0010] In the cutting insert as described above, the angle difference between the first portion and the second portion may be 0.2° or more and 10° or less.

[0011] In the cutting insert as described above, the angle difference between the first portion and the second portion may be 1° or more and 5° or less.

[0012] In the cutting insert as described above, a step may be formed between the flank face of the minor cutting edge and the abutment face located below the flank face.

[0013] In the cutting insert as described above, the step may become larger from the minor cutting edge toward the major cutting edge.

[0014] In the cutting insert as described above, the step may be uniformly increased from the minor cutting edge toward the major cutting edge.

[0015] In the cutting insert as described above, an inclined surface may be provided between the flank surface and the abutment surface of the minor cutting edge.

[0016] In the cutting insert as described above, the minor cutting edge on the lower surface may be positioned further outward from the center of the cutting insert than the major cutting edge on the upper surface when viewed from above.

[0017] The cutting insert as described above may have a convex R portion between the main cutting edge and the minor cutting edge, which is formed at a position closer to the minor cutting edge than an axis passing through the center of the side on which the main cutting edge and the minor cutting edge are formed.

[0018] Another aspect of the present invention is a cutting tool including the cutting insert as described above.

[0019] The cutting tool may be a rotary cutting tool. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view showing a cutting tool according to an embodiment of the present invention. [Figure 2] FIG. 2 is a view of the cutting tool as viewed from the tip end side along the central axis. [Figure 3] FIG. [Figure 4] 1 is a top view of a cutting insert according to an embodiment of the present invention, viewed from the top surface side perpendicular to the bottom surface thereof. FIG. [Figure 5] FIG. 2 is a perspective view of the cutting insert as seen from the side where the contact surface thereof is visible. [Figure 6] FIG. 2 is a side view of the cutting insert as seen from a side where the abutment surface is located. [Figure 7] 7 is a top view showing the minor cutting edge and its surrounding area as viewed in the direction of the arrow in FIG. 6. [Figure 8]8 is an enlarged view of the cross-sectional shape of a portion indicated by symbol VIII in FIG. 4. FIG. [Figure 9] 9 is an enlarged view of the cross-sectional shape of a portion indicated by symbol IX in FIG. 4. FIG. [Figure 10] 1 is a diagram showing an outline of the shape of a cutting insert attached to a cutting tool. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, preferred embodiments of a cutting insert and a cutting tool including the same according to the present invention will be described in detail with reference to the drawings (see FIG. 1, etc.).

[0022] <Outline of cutting inserts> The cutting insert 10 shown in FIG. 4 and other figures is configured as an insert that can be used on both sides by flipping it over and attaching it to a tool body 150 of a cutting tool 100 (see FIGS. 1 to 3 ) using a male screw 160 or the like. The cutting insert 10 of this embodiment has an upper surface 17, which is a first end surface facing upward in the plane of the paper in FIG. 6 , a lower surface 19, which is a second end surface facing downward in the opposite plane of the paper, and a peripheral side surface 15 formed to connect the upper surface 17 and the lower surface 19. The peripheral side surface 15 has a first peripheral side surface portion 11, a second peripheral side surface portion 12, a third peripheral side surface portion 13, and a fourth peripheral side surface portion 14 connecting the upper surface 17 and the lower surface 19. In a top view from the upper surface 17 side perpendicular to the lower surface 19 (see FIG. 4 ), the shape of the upper surface 17 appears to be either a rectangle or a hexagon. When viewed as a quadrangle, the shape is roughly a parallelogram or an approximate parallelogram in which one set of substantially parallel ridges is longer than the other set of substantially parallel ridges. When viewed as a hexagon, the shape is such that one set of substantially parallel ridges is longer than the other two sets of substantially parallel ridges. A through-hole 10H for fixing to a cutting tool 100 is formed in the center of the cutting insert 10, penetrating the upper surface 17 and the lower surface 19, along the central axis A1 (see Figures 4, 5, etc.).

[0023] The second peripheral side surface portion 12 is a surface that is perpendicular to the central axis AX1 and faces a second direction D2 corresponding to the downward direction on the paper in the figure, and is connected to the long ridges of the upper surface 17 and the lower surface 19. The fourth peripheral side surface portion 14 is a surface that is perpendicular to the central axis AX1 and faces a fourth direction D4 corresponding to the upward direction on the paper in the figure, and is connected to the long ridges of the upper surface 17 and the lower surface 19. The first peripheral side surface portion 11 is a surface that faces a first direction D1 corresponding to the left direction on the paper in Figure 4, and is connected to the short ridges of the upper surface 17 and the lower surface 19. The third peripheral side surface portion 13 is a surface that faces a third direction D3 corresponding to the right direction on the paper in the figure, and is connected to the short ridges of the upper surface 17 and the lower surface 19. The first direction D1 and the third direction D3 are parallel to and opposite each other, and are perpendicular to the second direction D2 and the fourth direction D4, which are parallel to and opposite each other. The second circumferential side portion 12 and the fourth circumferential side portion 14 are formed to be flat or generally flat and parallel to each other, except for the connection portions with the first circumferential side portion 11 or the third circumferential side portion 13 at both ends (see Figure 4, etc.).

[0024] The upper surface 17 has a flat surface 17A formed to surround the through hole 10H (see FIGS. 4 and 5). The flat surface 17A is a surface that comes into contact with the bottom surface of the insert seat 154 of the tool body 150 of the cutting tool 100 when machining is performed using the cutting edge formed on the lower surface 19 (see FIG. 10).

[0025] A cutting edge 20 is formed in at least a portion of a connection region 17P between the upper surface 17 and the first peripheral side surface portion 11 (see FIG. 5, etc.). Similarly, a cutting edge 20 is formed in at least a portion of a connection region 17S between the upper surface 17 and the third peripheral side surface portion 13, a connection region 19P between the lower surface 19 and the first peripheral side surface portion 11, and a connection region 19S between the lower surface 19 and the third peripheral side surface portion 13. These four sets of cutting edges 20 are composed of cutting edge portions 20a to 20d that are arranged in positions that are rotationally symmetric with respect to the central axis AX1, the axis B, and the axis C. The cutting edge portions 20a and 20b are formed in the intersection region between the upper surface 17 and the peripheral side surface 15 so as to have a 180° rotationally symmetric shape (point symmetric shape) around the central axis AX1. The other pair of cutting edges 20c, 20d are formed in the intersection region of the lower surface 19 and the peripheral side surface 15 so as to have a 180° rotational symmetry shape with respect to the pair of cutting edges 20a, 20b about axis B or axis C (see FIGS. 4 and 5). The other pair of cutting edges 20c, 20d are also formed so as to have a 180° rotational symmetry shape with respect to the central axis AX1. Note that axis B is an axis that perpendicularly intersects the center point of central axis AX1 (a point equidistant from the upper surface 17 and the lower surface 19) and extends in the second direction D2 and the fourth direction D2. Axis C is an axis that passes through the center point of central axis AX1 (a point equidistant from the upper surface 17 and the lower surface 19) and is perpendicular to central axis AX1 and axis B (see FIG. 4, etc.).

[0026] For example, if the cutting edge portion 20a in at least a part of the intersection region between the upper surface 17 and the first peripheral side surface portion 11 is damaged during cutting, rotating the cutting insert 10 180° around the central axis AX1 allows cutting to be performed using the unused cutting edge portion 20b on the opposite side of the upper surface 17. Furthermore, if both of the two cutting edge portions 20a and 20b on the upper surface 17 are damaged, rotating the cutting insert 10 around the axis B or the axis C to flip it over allows cutting to be performed using either of the unused cutting edge portions 20c and 20d on the lower surface 19. Furthermore, even after flipping it over, rotating it 180° in the same plane allows a total of four cutting edge portions to be used (four times). Since each of the cutting edge portions 20a to 20d has the same configuration, the following description will focus on the cutting edge portion 20a in the intersection region between the upper surface 17 and the first peripheral side surface portion 11.

[0027] <Cutting edge structure> The cutting edge portion 20a is formed with a major cutting edge 21 and a minor cutting edge (inner cutting edge) 22, which become the cutting edge 20 during cutting, as well as a curved R portion 23 provided between the major cutting edge 21 and the minor cutting edge 22 (see FIG. 6, etc.). The minor cutting edge 22 is located closer to the fourth peripheral side surface portion 14 than the major cutting edge 21. Although not specifically numbered, the R portions (corners) at the four corners of the outer periphery can be considered to be included as part of the major cutting edge 21.

[0028] When the cutting insert 10 is attached to the cutting tool 100, the major cutting edge 21 faces the outer periphery of one end face of the cutting tool 100 and is suitable for flat surface machining. When the cutting insert 10 is attached to the cutting tool 100, the minor cutting edge 22 faces the inside of the cutting tool 100 and functions as a blade (sometimes referred to as an inner blade) suitable for ramping and the like. When the cutting insert 10 is attached to the cutting tool 100, the R portion 23 faces the one end face of the cutting tool 100 and functions as a wiper edge.

[0029] The first peripheral side surface portion 11 (and the third peripheral side surface portion 13) has portions that become the flanks 21f, 22g of the cutting edge portion 20a and a portion that functions as a contact surface (constraint surface) 40 (see FIGS. 4, 10, etc.). At least a portion of the contact surface 40 abuts against at least two non-linear locations on the side wall 1156 of the insert seat 154 of the tool body 150 of the cutting tool 100, and constrains the cutting insert 10 so that it does not rotate about the central axis AX1 even when a moment acts on the cutting insert 10 due to a reaction force (cutting force) from the workpiece during cutting (see FIG. 10).

[0030] The major cutting edge 21 is formed in at least a part of the intersection region between the top surface 17 and the peripheral side surface 15 (in other words, in the connection region 17P between the top surface 17 and the first peripheral side surface 11 for the cutting edge portion 20a), and the minor cutting edge 22 is also formed in at least a part of the intersection region between the top surface 17 and the peripheral side surface 15 (in other words, in the connection region 17P between the top surface 17 and the first peripheral side surface 11 for the cutting edge portion 20a). The major cutting edge 21 is an inclined blade that is generally linear or includes a part of an upwardly convex curve in a side view viewed facing the first peripheral side surface 11 (see FIG. 4, etc.). The inclination angle of the major cutting edge 21 with respect to the flat surface 17A in FIG. 6 (however, this is the angle of the linear portion that approximates part of the major cutting edge 21) can be set appropriately depending on specifications, etc. The major cutting edge 21 is formed so as to gradually rise in the thickness direction (direction along the central axis AX1) of the cutting insert 10 as it moves away from the minor cutting edge 22 and approaches the second peripheral side surface portion 12 (see FIG. 6, etc.).

[0031] <Contact surface and minor cutting edge structure> In the cutting insert 10 of this embodiment, the abutment surface 40 is disposed perpendicular to the flat surface 19A of the lower surface 19. The abutment surface 40 has at least a linear first portion 41A in a top view (see FIGS. 6 and 7). The minor cutting edge 22 has at least a linear second portion 22B in a top view. Furthermore, the angle at which the linear first portion 41A of the abutment surface 40 is disposed is different from the angle at which the linear second portion 22B of the minor cutting edge 22 is disposed in a top view. More specifically, when the first portion 41A is used as a reference, the angle of the second portion 22B is changed in a direction in which the interior angle with a virtual straight line 21VL that approximately extends the major cutting edge 21 becomes smaller (see FIG. 7). In other words, if the interior angle formed by the virtual straight line 21VL that approximates and extends the main cutting edge 21 and the linear first portion 41A is θ1, and the interior angle formed by the virtual straight line 21VL that approximates and extends the main cutting edge 21 and the linear second portion 22B is θ2, then the relationship θ1 > θ2 holds.

[0032] In this case, the angle difference between the angle at which the linear first portion 41A of the abutment surface 40 is disposed and the angle at which the linear second portion 22B of the minor cutting edge 22 is disposed (this angle difference is equal to the value of θ1-θ2) should be in the range of 0.2° to 10°, and preferably in the range of 1° to 5°. A suitable example of this angle difference is 1.2°.

[0033] Furthermore, a step 60 is formed between the flank 22f of the minor cutting edge 22 and the abutment surface 40 located below the flank 22f (see Figs. 8 and 9). This step 60 is formed so that the minor cutting edge 22 or its flank 22f protrudes outward from the abutment surface 40, so that the minor cutting edge 22 or its flank 22f is in a so-called overhanging shape. Such a step 60 may be formed, for example, in a step shape (crank shape), but in the cutting insert 10 of this embodiment, the step 60 is formed by an inclined surface 61 provided between them (see Figs. 8 and 9). Furthermore, in the cutting insert 10 of this embodiment, the step 60 (size H) is formed so as to increase from the minor cutting edge 22 toward the major cutting edge 21. In this case, The rate of change of the step 60 (size H) may be uniform (the rate of change is constant when moving from the minor cutting edge 22 to the major cutting edge 21), or it may not be constant but may change along the way.

[0034] As described above, in the cutting insert 10 of this embodiment, in which the step 60 is formed between the flank 22f of the minor cutting edge 22 and the abutment surface 40 located below the flank 22f and the minor cutting edge 22 or the flank 22f is, so to speak, overhanging, the minor cutting edge 22 on the lower surface 19 is located more outward from the center (central axis AX1) of the cutting insert 10 than the major cutting edge 21 on the upper surface 17, and is in a state of protruding outward, as seen from above (see FIG. 4). Incidentally, in this embodiment, the minor cutting edge 22 is visible on the lower surface 17 in a top view because it overhangs outward from the abutment surface 40 (see FIG. 4). However, if the minor cutting edge 22 were not overhanging and located more inward from the abutment surface 40, the minor cutting edge 22 would not be visible in a top view as described above. In this case, the positional relationship may be considered, for example, in a perspective view (a view showing a perspective state).

[0035] In addition, in such a cutting insert 10, the R portion 23 is formed to have a convex shape between the major cutting edge 21 and the minor cutting edge 22, at a position closer to the minor cutting edge than an axis passing through the center of the side on which the major cutting edge 21 and the minor cutting edge 22 are formed (see FIGS. 4 and 7). Note that the shape of the R portion 23 is not limited to being formed in an arc shape, and for example, a linear wiper edge may also be formed. Alternatively, the R portion 23 may not be round, and only a linear wiper edge may be formed as a corner portion.

[0036] As explained so far, the cutting insert 10 of this embodiment is arranged so that the abutment surface 40 on the underside of the minor cutting edge 22 is parallel to the central axis AX1 of the insert, and when viewed from above, the angle of the minor cutting edge 22 is larger than the angle of the abutment surface 40 on the underside of the minor cutting edge 22, thereby enabling the minor cutting edge 22 to be made longer while ensuring secure restraint of the cutting insert 10 in the insert seat 154. Generally, in the cutting insert 10, maintaining the relative positional relationship between the minor cutting edge 22 and the abutment surface 40 shortens the length of the minor cutting edge 22, which poses a problem of increasing the angle restriction during inclined machining. However, as described above, by differentiating the angle between the linear first portion 41A of the abutment surface 40 and the linear second portion 22B of the minor cutting edge 22, and by configuring the interior angle θ2 between the virtual line 21VL, which approximates the major cutting edge 21, and the linear second portion 22B to be smaller than the interior angle θ1 between the virtual line 21VL, which approximates the major cutting edge 21, and the linear first portion 41A (θ2<θ1), it is possible to lengthen the minor cutting edge 22. With this cutting insert 10, the angle restriction during inclined machining (ramping) can be alleviated or eliminated even when the abutment surface 40 and the major cutting edge 21 are designed to be twisted. That is, in inclined machining (ramping machining), three cutting processes are performed simultaneously, namely a) peripheral cutting by the major cutting edge 21, b) bottom cutting by the R portion 23, and c) ramping machining by the minor cutting edge 22. The above-described cutting insert 10 improves the performance of c) ramping machining by the minor cutting edge 22. To give a specific example, it is expected that the inclination angle during ramping machining, which was about less than 1°, can be increased to about 1.5° by using the above-described cutting insert 10.

[0037] <Cutting tool overview> The cutting insert 10 described so far is attached to an insert seat 154 of a cutting tool 100 and used for cutting (see FIGS. 1, 10, etc.). The insert seat 154 has a bottom surface, and a female thread is formed so as to open to the bottom surface. A male screw 160 passing through a through hole 10H of the cutting insert 10 is screwed into the female thread, and the head of the male screw 160 presses the enlarged portion in the through hole 10H, and the cutting insert 10 is fixed to the tool body 150 by bringing the flat surface 19A formed on the lower surface 19 into contact with the bottom surface of the insert seat 154 while moving the side wall 156 to at least two positions that are not on a straight line. The cutting tool 1 is used, for example, as a rotary cutting tool such as a drill, or a milling cutter (turning tool), and further used as a high-feed cutter, etc.

[0038] The above-described embodiment is a preferred example of the present invention, but is not limited thereto, and various modifications are possible within the scope of the present invention. For example, in the above-described embodiment, the cutting insert 10 provided with the through hole 10H is described as an example, but this is merely a preferred example, and it goes without saying that the present invention can also be applied to a cutting insert 10 not provided with the through hole 10H, although this is not particularly shown. [Industrial Applicability]

[0039] The present invention is suitable for application to a cutting insert and a cutting tool including the same. [Explanation of symbols]

[0040] 10...Cutting insert 10H...Through hole 11…First peripheral side part 12…Second peripheral side part 13...Third peripheral side part 14…Fourth peripheral side part 15…Circumferential side 17…Top surface 17A…Flat surface 17P: Connection area with the first periphery side 17S: Connection area with the third periphery side 19…Bottom surface 19A…Flat surface 19P: Connection area with the first periphery side part 19S…Connection area with the third periphery side 20...Cutting edge 20a, 20b, 20c, 20d...Cutting edge 21...Main cutting edge 21f...Flank face of main cutting edge 21VL...An imaginary straight line that approximates and extends the main cutting edge 22...minor cutting edge 22f...Flank face of minor cutting edge 22B...Straight second section 23…R section 40…Contact surface 41A...Straight first section 50...Through hole 60...Step 100…Cutting tools 100A…Center axis 101...Tip 150...Tool body 154...insert seat 156...Side wall 160...Male thread θ1...The internal angle between the virtual line that approximates the main cutting edge and the first linear portion θ2...The internal angle between the virtual line that approximates the main cutting edge and the second straight line AX1…center axis B…Axis line C...Axis (Axis passing through the center of the edge where the main cutting edge and the minor cutting edge are formed) D1…first direction D2…Second direction D3…Third direction D4...4th direction, H: Size of step

Claims

1. A cutting insert for use in a cutting tool, an upper surface serving as a first end surface; a lower surface serving as a second end surface opposite to the upper surface; a peripheral side surface formed to connect the upper surface and the lower surface; a major cutting edge and a minor cutting edge formed in at least a part of an intersection region between the upper surface and the peripheral side surface and an intersection region between the lower surface and the peripheral side surface, respectively; a contact surface formed on one of the peripheral side surfaces; At least two flanks arranged above and below the contact surface; Equipped with the abutment surface is disposed perpendicular to the lower surface, When viewed from the upper surface side perpendicular to the lower surface, the contact surface has at least a linear first portion, When viewed from above, the minor cutting edge has at least a linear second portion on the one peripheral side surface portion where the first portion is located, of the peripheral side surface, When viewed from above, the linear first portion of the abutment surface is disposed at an angle different from that of the linear second portion of the minor cutting edge, A cutting insert, wherein, when the first portion is used as a reference, the angle of the second portion differs in a direction in which the interior angle between the second portion and a virtual line that approximately extends the main cutting edge becomes smaller.

2. The cutting insert according to claim 1 , wherein an extension line of the major cutting edge and an extension line of the minor cutting edge intersect at an interior obtuse angle in a top view.

3. The cutting insert according to claim 1 , wherein the angle difference between the first portion and the second portion is equal to or greater than 0.2° and equal to or less than 10°.

4. The cutting insert according to claim 3 , wherein the angle difference between the first portion and the second portion is equal to or greater than 1° and equal to or less than 5°.

5. The cutting insert according to claim 1 , wherein a step is formed between a flank surface of the minor cutting edge and the abutment surface located below the flank surface.

6. The cutting insert according to claim 5 , wherein the step increases from the minor cutting edge toward the major cutting edge.

7. The cutting insert according to claim 6 , wherein the step increases uniformly from the minor cutting edge toward the major cutting edge.

8. The cutting insert according to claim 5 , wherein an inclined surface is provided between the flank surface of the minor cutting edge and the abutment surface.

9. The cutting insert according to claim 1 , wherein, in a top view, the minor cutting edge on the lower surface is positioned more outward from the center of the cutting insert than the major cutting edge on the upper surface.

10. 2. The cutting insert according to claim 1, further comprising a convex R portion formed between the major cutting edge and the minor cutting edge at a position closer to the minor cutting edge than an axis passing through the center of the side on which the major cutting edge and the minor cutting edge are formed.

11. A cutting tool comprising the cutting insert according to any one of claims 1 to 9.

12. The cutting tool of claim 11 which is a rotary cutting tool.

Images