Cutting insert and cutting tool comprising the cutting insert

Abstract

To provide a cutting insert that can suppress a corner cutting blade from being damaged more than before to improve a tool service life further, and a cutting tool.SOLUTION: A cutting insert 10 has two end faces 10U and 10L and a side face 10D connected to the end faces, and is formed in a nearly polygonal shape, which comprises a cutting blade 2A and a flank face having a negative flank angle connected to the cutting blade 2A, on the side surface 10S. The cutting blade 2A has a main cutting blade 21 and an inner blade 22, and a corner cutting blade 23 formed in a curve shape between the main cutting blade and the inner blade. The flank face has side face parts S1, S2 and S3 connected to the main cutting blade 21, the inner blade 22 and the corner cutting blade 23, respectively. A length W in a width direction of the side surface part S3 is largest at a boundary A between the side face parts S3 and S1. The side face part is formed so that the part gradually becomes smaller from the boundary A toward at least a middle toward a boundary G between the side face parts S3 and S2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Recently, there has been an increasing demand for rotary cutting tools capable of high-feed machining in order to improve machining efficiency. In response to this demand, for example, Patent Document 1 describes a cutting insert and a cutting tool that are intended to improve chip removal and the wear resistance of the rake face corresponding to the cutting edge. However, with such conventional cutting inserts, the corner cutting edge connected to the main cutting edge may not be able to sufficiently suppress damage during machining depending on the height (width) of the corresponding flank. To address this issue, the present applicant has proposed, for example, in Patent Document 2, a cutting insert and a rotary cutting tool that can suppress damage by focusing on the shape of the corner cutting edge and its surroundings. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2023 / 176619 [Patent Document 2] Patent No. 7011689 Summary of the Invention [Problem to be solved by the invention]

[0004] Cutting inserts are typically designed to optimize the cutting performance of the main cutting edge. Furthermore, cutting inserts, especially negative inserts that can be used on both sides, have relatively low design freedom for the clearance angle, and the clearance angle is often roughly determined. Therefore, unless optimal design is implemented for the main cutting edge and other special measures are taken, the clearance angle of the portion corresponding to the corner cutting edge is usually unavoidably large. This can make it difficult to adequately prevent damage to the corner cutting edge in some cases.

[0005] Therefore, the present disclosure aims to provide a cutting insert that can further suppress damage to corner cutting edges than conventional methods, thereby significantly improving tool life, and a cutting tool equipped with the cutting insert. [Means for solving the problem]

[0006] In order to solve the above problems, the present disclosure employs the following configuration.

[0007] [1] An example of a cutting insert according to the present disclosure has two opposing end faces and side faces connected to the two end faces. The end faces have a generally polygonal shape in a plan view, cutting edges formed on the edges (outer edges) of the end faces, and flanks having a negative clearance angle connected to the cutting edges at the side faces. The cutting edges include a first cutting edge, a second cutting edge, and a third cutting edge formed between the first cutting edge and the second cutting edge and curved in a plan view. The flanks have a first side portion, a second side portion, and a third side portion connected to the first cutting edge, the second cutting edge, and the third cutting edge, respectively. The width direction length of the third side portion is greatest at a first boundary between the third side portion and the first side portion and gradually decreases at least partway from the first boundary to a second boundary between the third side portion and the second side portion. In the present disclosure, a "negative clearance angle" indicates that the clearance angle is formed so as to slope outward as it increases away from the cutting edge. Furthermore, the "widthwise length" refers to the length in a direction perpendicular or approximately perpendicular to the reference plane P1 of the cutting insert described later (i.e., the direction along or approximately along the central axis Az also described later) (in other words, it can also be called the actual "vertical width" or "height").

[0008] In this configuration, unlike conventional cutting edge designs, the clearance angle of the third side portion as the clearance surface corresponding to the third cutting edge (corresponding to the conventional "corner cutting edge"), which is curved in a planar view, is not too large compared to the clearance angle of the first side portion as the clearance surface corresponding to the first cutting edge (corresponding to the conventional "main cutting edge"), and the wedge angle of the third cutting edge is not too small compared to the wedge angle of the first cutting edge.

[0009] [2] Furthermore, from a different viewpoint from the above configuration, the cutting insert may be formed so that the clearance angle of the third side surface portion gradually increases in the negative direction from either the first boundary between the third side surface portion and the first side surface portion or the second boundary between the third side surface portion and the second side surface portion to the other, and then gradually decreases in the negative direction from that point to the other.

[0010] [3] More specifically, the position at which the clearance angle of the third side portion is maximum may be configured to be closer to the first boundary than half (50%) of the distance from the first boundary to the second boundary.

[0011] [4] In such a configuration, the cutting insert has a through hole provided so as to penetrate two end faces, and a plurality of cutting edges are formed on at least one of the two end faces, and the plurality of cutting edges may be rotationally symmetrical with respect to each other with respect to the central axis of the through hole. This allows the cutting insert according to the present disclosure to be replaced and reused multiple times with one end face, which can contribute to improving economy.

[0012] [5] In this case, more specifically, an example can be a configuration in which the multiple cutting edges are rotationally symmetrical with respect to each other by 120° with respect to the central axis of the through hole, and the cutting insert has an approximately hexagonal shape when viewed in a plane of the end face.

[0013] [6] Furthermore, cutting edges may be formed on both of the two end faces, and the cutting insert may have a virtual rotation axis along which the cutting edges on the two end faces are arranged with 180° rotational symmetry with respect to each other. In other words, the cutting edges on both end faces may be arranged with 180° rotational symmetry in the direction of turning over the two faces. This allows the cutting insert according to the present disclosure to be used interchangeably with double-sided specifications, which can contribute to further improving economy.

[0014] [7] An example of a cutting tool according to the present disclosure can be effectively configured with a rotating body and a cutting insert according to the present disclosure attached to the body. That is, the cutting insert has two opposing end faces and side faces connected to the two end faces, and the end faces have a generally polygonal shape in a plan view, cutting edges formed on the sides (outer edges) of the end faces, and flank faces having a negative clearance angle connected to the cutting edges at the side faces. The cutting edges also include a first cutting edge, a second cutting edge, and a third cutting edge formed between the first cutting edge and the second cutting edge and curved in a plan view. Furthermore, the flank faces have first side portions, second side portions, and third side portions connected to the first cutting edge, the second cutting edge, and the third cutting edge, respectively.

[0015] The width direction length of the third side surface portion is greatest at the first boundary between the third side surface portion and the first side surface portion and gradually decreases from the first boundary at least partway toward the second boundary between the third side surface portion and the second side surface portion. Alternatively, the clearance angle of the third side surface portion may be gradually increased from either the first boundary between the third side surface portion and the first side surface portion or the second boundary between the third side surface portion and the second side surface portion toward the other, and then gradually decrease from that partway toward the other.

[0016] [8] [9] More specifically, at the third side portion of the cutting insert when attached to the body, the change in the true clearance angle of the third cutting edge relative to the rotation trajectory may be preferably within 3°, more preferably within 1.5°. This makes it possible to realize a cutting edge shape in which the fracture resistance of the third cutting edge is not significantly impaired compared to the first and second cutting edges. [Effects of the Invention]

[0017] According to the present disclosure, damage to the corner cutting edge can be more effectively prevented, thereby making it possible to further improve the tool life. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view schematically showing the overall configuration of a cutting insert provided in a cutting tool according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view (top view) of the cutting insert shown in FIG. [Figure 3] 3 is a side view of the cutting insert shown in FIG. 1, viewed from the direction along the line III-III shown in FIGS. 1 and 2.

[0023] FIG. [Figure 4] FIG. 2 is an enlarged perspective view showing the vicinity of the tip of the cutting tool according to the embodiment. [Figure 5] FIG. 2 is an enlarged side view showing the vicinity of the tip of the cutting tool according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, this embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in each drawing will be assigned the same reference numerals as much as possible, and redundant description will be omitted. Fig. 1 is a perspective view schematically showing the overall configuration of a cutting insert provided in a cutting tool according to this embodiment, Fig. 2 is a plan view (top view) of the cutting insert shown in Fig. 1, and Fig. 3 is a side view of the cutting insert shown in Fig. 1, viewed from the direction along line III-III shown in Figs. 1 and 2.

[0020] <Cutting insert 10> 1 to 3, the cutting insert 10 has an end face 10U (first end face) and an end face 10L (second end face) that face each other, and a side face 10S that connects the end faces 10U and 10L. For convenience, if the direction in which the end face 10U faces is defined as upward, the end face 10L faces downward, which is the opposite direction to the direction in which the end face 10U faces. In other words, the end faces 10U and 10L face vertically, while the side face 10S faces laterally, i.e., horizontally.

[0021] 1 and 2, the end faces 10U and 10L are formed with through holes H penetrating therethrough. In other words, FIG. 2 corresponds to a top view of the end face 10U viewed from above along the central axis Az of the through hole H, and FIG. 3 corresponds to a side view of the side face 10S viewed laterally from a direction perpendicular to the central axis Az of the through hole H. Furthermore, as shown in FIGS. 1 and 2, the cutting insert 10 has a substantially polygonal (substantially hexagonal) shape in a plan view, and the side face 10S has corners CA, CB, and CC formed with 120-degree rotational symmetry with respect to each other. That is, in FIG. 2, the side face 10S has corners CA, CB, and CC having the same shape, in that order, spaced 120 degrees apart counterclockwise. In this embodiment, these corners CA, CB, and CC are formed in a curved shape, such as a substantially arc-shaped shape, with a vertex angle of, for example, 80° to 100°.

[0022] Furthermore, cutting edges 2A, 2B, and 2C having the same structure are provided in this order at the edge of the end face 10U, i.e., at the intersection ridge between the end face 10U and the side face 10S, at intervals of 120° counterclockwise in Figures 1 and 2. In other words, these multiple cutting edges 2A, 2B, and 2C are formed to be 120° rotationally symmetrical with respect to each other (i.e., three-fold rotationally symmetrical) with respect to the central axis Az of the through hole H.

[0023] Each of the cutting edges 2A, 2B, and 2C includes a bottom cutting edge 20, a major cutting edge 21 (first cutting edge), a corner cutting edge 23 (third cutting edge), and an inner cutting edge 22 (second cutting edge), which are connected in this order counterclockwise in FIGS. 1 and 2 . The bottom cutting edge 20 is located at the leading edge of the rotary cutting tool 100 when the cutting insert 10 is attached to a body 50 (described later) and serves as a partition between the cutting edges 2A, 2B, and 2C. The bottom cutting edge 20 is formed, for example, in a substantially linear shape and functions to improve the finished surface of the cut portion. The major cutting edge 21 and the inner cutting edge 22 are, for example, linear in plan view, while the corner cutting edge 23 formed therebetween is curved (for example, substantially arc-shaped) in plan view. The corner cutting edge 23, like the corners CA, CB, and CC, is formed to have an apex angle of, for example, 80° to 100°. The main cutting edge 21 and the inner cutting edge 22 are not limited to being linear in plan view, but may be curved, such as an arc having a larger radius of curvature than the corner cutting edge 23, in plan view.

[0024] 3, the main cutting edge 21 is formed at an angle relative to the reference plane P1 (the horizontal plane in the figure) so as to move away from the bottom cutting edge 20. Meanwhile, the corner cutting edge 23 is formed as an arc-shaped convex portion relative to the reference plane P1 so as to move away from the main cutting edge 21 and then approach the reference plane P1 again. Meanwhile, the inner cutting edge 22 is formed as an arc-shaped concave portion relative to the reference plane P1 so as to move away from the corner cutting edge 23 and then approach the reference plane P1 again. The reference plane P1 is an imaginary plane that is perpendicular to the central axis Az of the through hole H and passes through the middle of the end faces 10U and 10L.

[0025] 1 and 2 show imaginary axes Ax and Ay as an example of two-dimensional coordinate axes existing on the reference plane P1. The cutting insert 10 is formed with 180-degree rotational symmetry (i.e., two-fold rotational symmetry) with respect to the imaginary axis Ay (a predetermined axis virtually penetrating the cutting insert along the end face) that intersects the bottom cutting edge 20 and the corner cutting edge 23 in a plan view, among the imaginary axes Ax and Ay. As such, the end face 10L provided on the opposite side of the cutting insert 10 opposite to the end face 10U has the same structure as the end face 10U. In other words, cutting edges 2A, 2B, and 2C with the same structure are formed on the side of the end face 10L, i.e., on the intersection ridge between the end face 10L and the side face 10S.

[0026] The area connecting to the cutting edges 2A, 2B, and 2C on the outer edge side of the end face 10U functions as a rake face. Furthermore, around the through hole H of the end faces 10U and 10L, when the end faces 10U and 10L are used as cutting edges, abutment surfaces (flat portions) are formed to fix the cutting insert 10 to the body 50 by being pressed against the tip seat of the body 50.

[0027] Furthermore, as shown in FIG. 3 , which mainly illustrates the cutting edge 2A and its surrounding area, the side surface 10S connected to the end surfaces 10U and 10L has a clearance surface including side portions S0, S1, S2, and S3 connected to the bottom cutting edge 20, the main cutting edge 21 (first cutting edge), the inner cutting edge 22 (second cutting edge), and the corner cutting edge 23 (third cutting edge). Each of these side portions S0, S1, S2, and S3 has a negative clearance angle, so-called a reverse positive surface. More specifically, the side portion S1 (first side portion) extends from one end of the main cutting edge 21 connected to the bottom cutting edge 20 to the other end of the main cutting edge 21 connected to the corner cutting edge 23. The side portion S2 (second side portion) extends from one end of the corner cutting edge 23 connected to the main cutting edge 21 to the other end of the corner cutting edge 23 connected to the inner cutting edge 22. Furthermore, the side surface portion S3 (third side surface portion) is formed from one end of the inner cutting edge 22 connected to the corner cutting edge 23 to the other end of the inner cutting edge 22 connected to another bottom cutting edge 20.

[0028] 3, the horizontal range of the side surface portion S3 connected to the corner cutting edge 23 is divided into six sections at approximately equal intervals, and the positions of each boundary A to G and the widthwise lengths of these boundaries are indicated by dashed double-headed arrows. If the widthwise lengths of the boundaries A to G are represented by W1 to W7, the cutting insert 10 of this embodiment is preferably configured so that the widthwise lengths of the side surface portion S3 satisfy the relationship represented by the following formula (1), for example.

[0029] W1>W2>W3≒W4≒W5≒W6≒W7 …(1) As described above, in the cutting insert 10, the widthwise length W of the side surface portion S3 is greatest at W1 at the boundary A (first boundary) between the side surface portions S3 and S1. That is, the cutting insert 10 is formed so that the widthwise length W gradually decreases to approximately W3 at least partway (near the boundary C) from the boundary A (first boundary) toward the boundary G (second boundary) between the side surface portions S3 and S2 (formula (1)).

[0030] Here, if the clearance angles at the boundaries A to G within the side portion S3 are represented by C1 to C7, the cutting insert 10 of this embodiment is preferably configured so that these clearance angles satisfy the relationships represented by the following equations (2) and (3), for example.

[0031] C1 <C2<C3 …(2) C3> C4>C5>C6>C7 …(3) As described above, the cutting insert 10 is formed so that the clearance angle of the side portion S3 gradually increases in the negative direction from the boundary A (first boundary) between the side portions S3 and S1 toward the boundary G (second boundary) between the side portions S3 and S2 (near boundary C) (formula (2)), and then gradually decreases in the negative direction from that midpoint (near boundary C) toward boundary G (formula (3)).

[0032] As shown by this tendency of the clearance angle, and as shown in Figure 3, the cutting insert 10 is configured so that the position (near boundary C) where the clearance angle of the side portion S3 is maximum is closer to boundary A (first boundary) than half the distance (near boundary D) from boundary A (first boundary) to boundary G (second boundary).

[0033] <Rotary cutting tool 100> Fig. 4 is an enlarged perspective view showing the vicinity of the tip of the cutting tool according to this embodiment, and is a view of a rotary cutting tool 100 (cutting tool) in which four cutting inserts 10 are attached to a body 50 that rotates around a rotation axis J, as viewed from the oblique tip side of the rotation axis J. Fig. 5 is an enlarged side view of the vicinity of the tip of the cutting tool according to this embodiment, and is a view of the rotary cutting tool 100 in the state shown in Fig. 4 as viewed from a direction parallel to the rotation axis J.

[0034] As shown in FIGS. 4 and 5 , the rotary cutting tool 100 includes a plurality of cutting inserts 10 and a body 50 to which the cutting inserts 10 are attached. The cutting inserts 10 are attached to the body 50 by threading a male thread inserted into the through hole H with a female thread formed in a tip seat of the body 50 and pressing the cutting insert 10 against the body 50 using the male thread. At this time, the end face 10U faces the direction in which the body 50 rotates, and the abutting surface of the end face 10L, facing the opposite direction, is pressed against the tip seat of the body 50. Furthermore, the side surface portion S0 of the side surface 10S faces downward relative to the rotation axis J in FIG. 5 . The corner cutting edge 23 of the cutting edge 2A at the corner portion CA is located at the outer periphery farthest from the rotation axis J and slightly protrudes radially outward from the body 50. Additionally, the end cutting edge 20 and the main cutting edge 21 protrude slightly downward relative to the body 50 relative to the rotation axis J.

[0035] The cutting insert 10 configured as described above and the rotary cutting tool 100 to which it is attached function as a double-sided, replaceable multi-function machining component. That is, the cutting insert 10 can be rotated at each of the end faces 10U and 10L and can be flipped over at the end faces 10U and 10L, allowing for multiple uses. This improves the economic efficiency of the tool.

[0036] Furthermore, in the cutting insert 10, unlike conventional cutting edge designs, the clearance angle of the side portion S3 serving as the clearance face corresponding to the corner cutting edge 23 is largest at boundary C, which is midway toward boundary G rather than boundary A (first boundary) between the side portions S3 and S1, as described above. As described above, according to the cutting insert 10, the clearance angle of the side portion S3 connecting to the corner cutting edge 23 is not excessively large compared to the clearance angle of the side portion S1 connecting to the main cutting edge 21, and the wedge angle of the corner cutting edge 23 is not excessively small compared to the wedge angle of the main cutting edge 21. This makes it possible to further suppress damage to the corner cutting edge 23 during machining when the cutting insert 10 is attached to the rotary cutting tool 100, compared to conventional cases, and as a result, it becomes possible to significantly improve the tool life.

[0037] More specifically, the present applicant measured the change in true clearance angle of the corner cutting edge 23 relative to the rotational trajectory at the side surface S3 of the cutting insert 10 for the rotary cutting tool 100 described above and confirmed that the change was kept very small, within 1.5°. Furthermore, several rotary cutting tools with true clearance angle changes ranging from 1.5° to 10° were actually prepared and a test was conducted to compare the tool lives of these rotary cutting tools. As a result, rotary cutting tools with a true clearance angle of 10° suffered earlier damage to the corner cutting edge and became unusable than rotary cutting tools with smaller true clearance angles. Furthermore, judging from the results of this comparative test as a whole, rotary cutting tools with a true clearance angle change of 3° or less were found to have significantly longer tool lives than rotary cutting tools with a true clearance angle change of 10°. These points also demonstrate the advantageous effect of the cutting insert 10 and rotary cutting tool 100 disclosed herein in suppressing damage to the corner cutting edge.

[0038] The present embodiment has been described above with reference to specific examples. However, this is for the purpose of facilitating understanding of the present disclosure and is not intended to limit the present disclosure. In other words, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art are also encompassed within the technical scope of the present disclosure as long as they comprise the features of the present disclosure. Furthermore, unless otherwise specified, the elements, arrangements, materials, conditions, shapes, dimensions, sizes, scales, etc. of the above-described specific examples are not limited to those exemplified and can be modified as appropriate. Furthermore, the elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise.

[0039] For example, the cutting insert according to the present disclosure may have four or more cutting edges equivalent to the cutting edges 2A, 2B, and 2C on each of the end faces 10U and 10L. In some cases, the cutting edges formed on the end faces 10U and 10L may be arranged with 180° rotational symmetry about virtual axes Ax and Ay, which are predetermined axes virtually penetrating the cutting insert. The end cutting edge 20 may be formed not linearly but with an appropriate curvature to enhance sharpness. In this case, the end cutting edge 20 may also be considered a type of corner cutting edge. Furthermore, the end faces 10U and 10L may be appropriately provided with grooves or chip breakers connecting to the regions (rake faces) connecting to the cutting edges 2A, 2B, and 2C. Furthermore, the widthwise lengths W1 to W7 of the boundaries A to G of the side surface portion S3 may be gradually reduced overall from W1 to W7, i.e., may satisfy the relationship expressed by the following formula (4), for example. Alternatively, the widths W1 to W7 may be configured to increase partway and then decrease, that is, to satisfy the relationships expressed by the following formulas (5) and (6), for example.

[0040] W1>W2>W3>W4>W5>W6>W7 …(4) W1>W2>W3>W4 …(5) W4 <W5<W6<W7 …(6) [Explanation of symbols]

[0041] 2A, 2B, 2C...Cutting edge, 10...Cutting insert, 10L...End face (second end face), 10U...End face (first end face), 10S...Side face, 20...End cutting edge, 21...Main cutting edge (first cutting edge), 22...Inner cutting edge (second cutting edge), 23...Corner cutting edge (third cutting edge), 50...Body, 100...Rotary cutting tool (cutting tool), A-G...Boundary, Ax, Ay...Virtual axis, Az...Central axis, CA, CB, CC...Corner portion, H...Through hole, J...Rotary axis, P1...Reference surface, S0, S1, S2, S3...Side portion

Claims

1. A cutting insert having two end faces facing each other and side faces connected to the two end faces, the end faces forming a substantially polygonal shape in a plan view, a cutting edge formed on a side portion of the end surface; and a flank having a negative relief angle connected to the cutting edge at the side surface, The cutting edge includes a first cutting edge, a second cutting edge, and a third cutting edge formed between the first cutting edge and the second cutting edge and having a curved shape in the plan view, The flank surface has a first side portion, a second side portion, and a third side portion connected to the first cutting edge, the second cutting edge, and the third cutting edge, respectively; the width direction length of the third side surface portion is greatest at a first boundary between the third side surface portion and the first side surface portion, and gradually decreases from the first boundary at least partway toward a second boundary between the third side surface portion and the second side surface portion; Cutting insert.

2. A cutting insert having two end faces facing each other and side faces connected to the two end faces, the end faces forming a substantially polygonal shape in a plan view, a cutting edge formed on a side portion of the end surface; and a flank having a negative relief angle connected to the cutting edge at the side surface, The cutting edges include a first cutting edge and a second cutting edge each having a linear shape in the plan view, and a third cutting edge formed between the first cutting edge and the second cutting edge and having a curved shape in the plan view, The flank surface has a first side portion, a second side portion, and a third side portion connected to the first cutting edge, the second cutting edge, and the third cutting edge, respectively; the clearance angle of the third side surface portion gradually increases in a negative direction from one of a first boundary between the third side surface portion and the first side surface portion and a second boundary between the third side surface portion and the second side surface portion to the other, and then gradually decreases in the negative direction from the other boundary to the other. Cutting insert.

3. a position where the clearance angle of the third side surface portion is maximum is located closer to the first boundary than half the distance from the first boundary toward the second boundary; The cutting insert according to claim 1 or 2.

4. the cutting insert has a through hole provided so as to penetrate the two end surfaces, A plurality of cutting edges are formed on at least one of the two end surfaces, and the plurality of cutting edges are rotationally symmetrical with respect to each other with respect to the central axis of the through hole. The cutting insert according to claim 1 or 2.

5. The plurality of cutting edges are rotationally symmetrical to one another by 120° with respect to the central axis of the through hole, The cutting insert has a substantially hexagonal shape in a plan view of the end surface, The cutting insert according to claim 4.

6. The cutting edges are formed on both of the two end surfaces, The cutting insert has a virtual rotation axis on which the cutting edges of the two end surfaces are arranged rotationally symmetrically by 180° to each other. The cutting insert according to claim 1 or 2.

7. A rotating body and The cutting insert according to claim 1 or 2, which is attached to the body; A cutting tool comprising:

8. In the third side surface portion of the cutting insert in a state where the cutting insert is attached to the body, a change in a true clearance angle with respect to a rotation trajectory of the third cutting edge is within 3°. The cutting tool according to claim 7.

9. In the third side surface portion of the cutting insert in a state where the cutting insert is attached to the body, a change in a true clearance angle with respect to a rotation trajectory of the third cutting edge is within 1.5°. The cutting tool according to claim 7.

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