Cutting insert and cutting tool

Abstract

To improve rigidity of a cutting tool having a cutting insert and make a space occupied by the cutting tool narrower.SOLUTION: In a cutting insert 10, which has a first end face 11. a second end face 12 and a circumferential side face 13 connecting the first end face 11 to the second end face 12 and comprising a cutting blade 21, contour shapes of the first end face 11 and the second end face 12 have longitudinal directions and transverse directions respectively, and a rake face 22 facing the respective longitudinal directions of the first end face 11 and the second end face 12 is provided on at least a portion of the circumferential side face 13.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, cutting inserts used for cut-off processing on an automatic lathe are disclosed in Patent Documents 1 to 3.

[0003] The one described in Patent Document 1 has a generally parallelogram shape held by a holder, and has a rake face at its longitudinal tip that faces in a direction perpendicular to the longitudinal direction (laterally). This prior art discloses, as an example, a cutting insert that is held at the tip of the holder in a state where it protrudes outward along the longitudinal direction of the holder.

[0004] The cutting insert described in Patent Document 1 discloses the outer shape of the cutting insert according to the present invention, and the holder described in Patent Document 1 can be used in common with the cutting insert according to the present invention.

[0005] The cutting insert described in Patent Document 2 has a parallelogram shape held by a holder, and has a cutting surface at its longitudinal tip that faces in a direction perpendicular to the longitudinal direction (lateral direction). This cutting insert is held at the tip of the holder in a state where it protrudes outward (lateral direction) perpendicular to the longitudinal direction of the holder.

[0006] The cutting insert described in Patent Document 3 has a holder having a long, thin plate-shaped blade portion, a cutting insert inserted into the longitudinal tip of this plate-shaped blade portion, and the cutting insert has a cutting surface facing in the longitudinal direction. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] WO2016 / 093275A1 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-18605 [Patent Document 3] Special Publication No. 2020-506074 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the cutting insert described in Patent Document 2 is held in the holder in a state where it protrudes laterally outward from the holder, so the cutting tool consisting of the holder and the cutting insert occupies a large space. Therefore, even though the machine is small, it is difficult to avoid interference between the workpiece and the tool, and between adjacent tools, which is particularly required for automatic lathes that are equipped with many cutting tools for machining complex shapes into the workpiece.

[0009] The cutting insert described in Patent Document 3 is short and small, and in order to avoid the limitation on the machining diameter of the workpiece due to this, the cutting insert is inserted into a long, thin plate-shaped blade portion, and this plate-shaped blade portion is used by protruding outward along the longitudinal direction of the holder. Therefore, it is difficult to ensure the rigidity of the cutting tool including the cutting insert.

[0010] An object of the present invention is to improve the rigidity of a cutting tool having a cutting insert and reduce the space occupied by the cutting tool. [Means for solving the problem]

[0011] The invention of claim 1 is a cutting insert having a first end face, a second end face, and a peripheral side face connecting the first end face and the second end face and having a cutting edge, wherein the contour shapes of the first end face and the second end face each have a longitudinal direction and a lateral direction, and at least a portion of the peripheral side face is provided with a cutting surface facing the first end face and the second end face in each longitudinal direction.

[0012] The invention of claim 2 is the invention of claim 1, further comprising the cutting insert according to claim 1, wherein the cutting surface is provided on at least a portion of one side and the other side of the peripheral side surface along each longitudinal direction of the first end face and the second end face.

[0013] The invention according to claim 3 is the invention according to claim 1 or 2, further characterized in that the first end face is rotationally symmetrical by 180 degrees when viewed from the front in a direction perpendicular to the first end face.

[0014] The invention of claim 4 is the invention of claim 3, further characterized in that the contour shapes of the first end face and the second end face are each an approximately parallelogram having a longitudinal direction and a lateral direction.

[0015] The invention according to claim 5 is the invention according to claim 1, further characterized in that the first end face is mirror-symmetrical in a front view seen from a direction perpendicular to the first end face.

[0016] The invention of claim 6 is an invention of any one of claims 1 to 5, further comprising at least one uneven portion provided on the peripheral side surface at a portion that intersects with each of the short directions of the first end face and the second end face, and that has an uneven shape.

[0017] The invention of claim 7 is an invention of any one of claims 1 to 6, further characterized in that the cutting face is set inward and away from a straight line circumscribing the peripheral side surface along each longitudinal direction of the first end face.

[0018] An eighth aspect of the present invention is a cutting tool including the cutting insert according to any one of the first to seventh aspects and a holder for holding the cutting insert.

[0019] The invention of claim 9 is the invention of claim 8, further characterized in that the cutting insert is held at the tip of the holder in a state where it protrudes outward along the longitudinal direction of the holder, and its longitudinal tip has a cutting surface facing in the longitudinal direction. [Effects of the Invention]

[0020] (Claim 1) (a) The cutting insert has a rake face on at least a portion of the peripheral side surface that faces the first end face and the second end face in the longitudinal direction. Therefore, the main component of the cutting force acting on the rake face acts in the longitudinal direction of the cutting insert, making it difficult for a cutting tool including such a cutting insert to bend, thereby improving its rigidity. Furthermore, in machine tools in which the tool post is located above the central axis of the workpiece, chips are discharged in the longitudinal direction of the cutting insert (downward), improving chip disposal. Note that many machine tools have the tool post located on the upper side.

[0021] (Claims 2 to 5) (b) The cutting insert has a rake face on at least a portion of one side and the other side of the circumferential side along the longitudinal direction of each of the first end face and the second end face, whereby the two rake faces can be used in turn by reattaching the cutting insert within the cutting tool, which is highly economical.

[0022] (Claim 6) (c) The cutting insert has at least one uneven portion provided on its peripheral side surface at a portion intersecting the short direction of each of the first end face and the second end face, forming an uneven shape. As a result, when the main component of the cutting force acting on the rake face acts in the longitudinal direction of the cutting insert, the cutting insert is securely held without slippage within the cutting tool due to the engagement between the uneven portion and an uneven locking portion provided on the cutting tool so as to correspond to the uneven portion.

[0023] (Claim 7) (d) The cutting insert has a rake face set inward away from a straight line L (FIG. 1) that circumscribes the peripheral side surface along the longitudinal direction of the first end face. As a result, when the cutting insert is attached to a holder so that the longitudinal direction of the cutting insert is along the longitudinal direction of the holder, the rake face of the cutting insert can be accommodated within a width dimension K (FIG. 2) of the holder that intersects with the longitudinal direction. Therefore, a portion of the workpiece can be positioned within the width dimension K of the holder and cut, and even large workpieces can be pulled between adjacent cutting tools, allowing for space-saving parting-off.

[0024] The force that the workpiece exerts on the cutting insert is only a compressive force, and the effect of bending force is significantly reduced, which is advantageous in terms of rigidity.

[0025] (Claim 8) (e) The above (a) to (d) can be realized in cutting tools.

[0026] (Claim 9) (f) In a cutting tool, the cutting insert is held at the tip of the holder in a state in which it protrudes outward along the longitudinal direction of the holder, and its longitudinal tip has a rake face facing in the longitudinal direction. This prevents the cutting insert from protruding sideways from the holder toward adjacent cutting tools, reducing the space occupied by the cutting tool consisting of the holder and cutting insert. Therefore, in an automatic lathe or the like equipped with many cutting tools for machining complex shapes in a workpiece, interference between the workpiece and the tool, and interference between adjacent tools, can be easily avoided.

[0027] (g) In a cutting tool, when multiple cutting tool holders are attached to a tool rest that is movable in two directions perpendicular to the rotation axis of the workpiece, the rake face of the cutting insert of each cutting tool faces downward. Therefore, by feeding the tool rest vertically so that the cutting edge of the cutting insert is at the center height of the workpiece, and then feeding the tool rest horizontally (including diagonally horizontally) in that state to cut, the chips can be discharged in the direction that they naturally fall. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 shows a cutting insert according to one embodiment of the present invention, where (A) is a front view, (B) is a side view, and (C) is an end view. [Figure 2] FIG. 2 shows the cutting insert held in the holder, where (A) is a front view, (B) is a rear view, (C) is a side view, and (D) is an end view. [Figure 3] FIG. 3 is a front view showing the cutting and grooving process using a cutting tool. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the configuration of various rake faces of a cutting insert. [Figure 5] FIG. 5 is a front view showing a plurality of cutting tools attached to a tool rest. [Figure 6] FIG. 6 is a front view showing the positional relationship between the cutting tool attached to the tool rest and the workpiece. [Figure 7] FIG. 7 is a front view showing a cutting insert according to a modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cutting insert 10 according to one embodiment of the present invention, FIG. 2 shows a cutting tool 40 configured by holding the cutting insert 10 in a holder 30, FIG. 3 shows the state of parting and grooving using the cutting tool 40, FIG. 4 shows the shapes of various cutting faces provided on the cutting insert 10, FIG. 5 shows the state of the cutting tool 40 attached to a tool post 50 of a cutting machine together with other adjacent cutting tools 41, and FIG. 6 shows the positional relationship between the cutting tool 40 attached to the tool post 50 and the workpiece W.

[0030] In this specification, when viewed from the front (FIGS. 3 and 6) of the tool rest 50 to which the cutting tool 40 is attached, the vertical direction perpendicular to the rotation axis (Z axis) of the workpiece W is defined as the X direction, and the horizontal direction is defined as the Y direction. The X and Z directions are aligned with the X and Z axis directions of a lathe or the like.

[0031] Moreover, the cutting insert 10 according to this embodiment is, as an example, a cutting insert for parting off, which removes unnecessary portions of a workpiece W and divides the workpiece by pressing the cutting edge radially (in a direction perpendicular to the rotation axis of the workpiece W) against the rotating workpiece W. However, the present invention is not limited to this, and can be widely applied to cutting inserts for cutting the outer diameter of a workpiece W by pressing the cutting edge in a direction parallel to the rotation axis of the workpiece, as well as other cutting inserts and cutting tools.

[0032] 1, the cutting insert 10 has a first end face 11, a second end face 12, and a peripheral side face 13 connecting the first end face 11 and the second end face 12. The peripheral side face 13 is parallel to the direction along the hole axis of a clamping hole 14H described later.

[0033] The cutting insert 10 has a main body 14 with a clamping hole 14H penetrating a first end face 11 and a second end face 12, and has a cutting edge 20 adjacent to the main body 14. The cutting edge 20 has a cutting edge 21 formed at an acute angle of the peripheral side surface 13.

[0034] The cutting edge 21 comprises a leading cutting edge formed at the intersecting ridge between the rake face 22 and the clearance face 23 described later, and a side cutting edge formed at the intersecting ridge between the rake face 22 and the first end face 11 (and the second end face 12).

[0035] The cutting insert 10 is fixed and held in place on the mounting seat 31 of the holder 30 by screwing a tightening screw 15, which is inserted into the clamp hole 14H of the main body 14, into a threaded portion provided on the holder 30.

[0036] When the main body 14 of the cutting insert 10 is fixed and held to the mounting seat 31 of the holder 30 using the clamping screw 15, the main body 14 has a fastening surface 14A at the center of the first end face 11, through which the insertion port of the clamping screw 15 opens, and a seating surface 14B at the center of the second end face 12, which seats on the mounting seat 31 of the holder 30. In this embodiment, the fastening surface 14A is terraced and higher than the peripheral portion of the first end face 11, and the seating surface 14B is terraced and higher than the peripheral portion of the second end face 12.

[0037] The main body 14 of the cutting insert 10 is a part of the peripheral side surface 13 that intersects and faces the fastening surface 14A and the seating surface 14B, and has concave-convex portions 14R at two opposing portions that are perpendicular to the short direction of the first end face 11 and the second end face 12. The concave-convex portions 14R are engaged with concave-convex engaging portions 32, 33 that are provided in the form of upright walls on the mounting seat 31 of the holder 30 that holds the cutting insert 10.

[0038] The cutting insert 10 has a first end face 11 and a second end face 12 each having a contour shape that is a substantially parallelogram having a longitudinal direction and a lateral direction. That is, the cutting insert 10 has 180-degree rotational symmetry with respect to the axis of the clamping hole 14H of the main body portion 14. The cutting insert 10 has a main body portion 14 as a portion corresponding to the center in the longitudinal and lateral directions, a first cutting portion 20A as a portion on one side continuing from the main body portion 14 along the longitudinal direction of the cutting insert 10, and a second cutting portion 20B as a portion on the other side continuing from the main body portion 14 along the longitudinal direction of the cutting insert 10. That is, the cutting insert 10 has two acute-angled portions at opposing ends of the peripheral side surface 13, and the first cutting portion 20A and the second cutting portion 20B constitute the cutting portion 20 and have cutting edges 21 for cutting the workpiece W at the acute angles.

[0039] In the cutting insert 10, the longitudinal and lateral directions of the first end face 11 and the second end face 12, which form a substantial parallelogram, coincide with the longitudinal and lateral directions of the cutting insert 10.

[0040] In the cutting insert 10, the first cutting portion 20A and the second cutting portion 20B are rotationally symmetrical with respect to the axis of the clamp hole 14H, and therefore, the first cutting portion 20A will be described below as a representative thereof.

[0041] The first cutting portion 20A (same for the second cutting portion 20B) is the tip portion of the peripheral side surface 13 that connects the longitudinal tip portions of the first end face 11 and the second end face 12, and the aforementioned ridge line located near the acute vertex of the parallelogram of the first end face 11 and the second end face 12 serves as a cutting edge 21 (the second cutting portion 20B also has a cutting edge 21).

[0042] Furthermore, the first cutting portion 20A (the same applies to the second cutting portion 20B) is a part of the peripheral side surface 13 connecting the longitudinal tip ends of the first end face 11 and the second end face 12, and two surfaces intersecting the cutting edge 21 (ridge line) serve as a rake face 22 and a flank 23 (the second cutting portion 20B also has a rake face 22 and a flank 23). In this case, the cutting insert 10 has the rake face 22 as the surface of the first end face 11 and the second end face 12 facing in the longitudinal direction (for example, a surface perpendicular to the longitudinal direction), and the flank 23 as the surface of the first end face 11 and the second end face 12 facing in a direction perpendicular to the longitudinal direction (for example, a surface parallel to the longitudinal direction). Note that the flank 23 is also formed on the first end face 11 and the second end face 12, as described above.

[0043] The rake face 22 can have various three-dimensional shapes, such as an R-shaped (curved surface) as shown in the cross section of Fig. 4, a negative shape with an intersecting angle with the flank 23 of more than 90 degrees, a positive shape with an intersecting angle with the flank 23 of less than 90 degrees, a shape with a flat portion on one side, a stepped shape with a protrusion on one side, etc.

[0044] As shown in Figures 2 and 3, when the cutting insert 10 is held at the tip of the holder 30 using the clamping screw 15, the cutting insert 10 is held at the tip of the holder 30 with the longitudinal directions of the first end face 11 and the second end face 12 protruding outward along the longitudinal direction of the holder 30.

[0045] Here, the holder 30 is, for example, in the shape of a square bar with a rectangular cross section, and is provided with a mounting seat 31 for the cutting insert 10 at its longitudinal tip. The holder 30 has a recess formed by cutting out its tip, which serves as the mounting seat 31. The mounting seat 31 can accommodate one of the first cutting portion 20A and the second cutting portion 20B of the cutting insert 10, a part of the peripheral side surface 13, and the main body portion 14, and is provided with a flat seating surface on which the seating surface 14B of the cutting insert 10 seats. The holder 30 is provided with an internal thread portion for the clamping screw 15 to be inserted into the clamp hole 14H of the main body portion 14, which is threaded in a direction perpendicular to the seating surface of the mounting seat 31.

[0046] The holder 30 corresponds to the sides of the clamp hole 14H along the short-side direction of the cutting insert 10 seated and held on the mounting seat 31, and is provided with uneven locking portions 32, 33 each having a standing wall shape at two opposing portions sandwiching the mounting seat 31. The uneven locking portions 32, 33 of the holder 30 lock with two uneven portions 14R provided on the cutting insert 10 seated on the mounting seat 31, and stabilize the mounting position of the cutting insert 10 relative to the holder 30 so that it does not move in the longitudinal direction and short-side direction of the holder 30 which are perpendicular to the screw axis of the threaded portion provided on the holder 30.

[0047] When the cutting insert 10 is attached to the holder 30 in this manner, the cutting insert 10 and the holder 30 constitute a cutting tool 40. Then, as shown in Fig. 5, the holder 30 of the cutting tool 40 is attached to a tool post 50 of a cutting machine, and the cutting tool 40 is used to cut a workpiece W.

[0048] In the cutting tool 40, the cutting portion 20 (first cutting portion 20A and second cutting portion 20B) of the cutting insert 10 and the cutting face 22 of the cutting portion 20 are set inward and away from the straight line L circumscribing the peripheral side surface 13 along the respective short directions of the first end face 11 and the second end face 12, as shown in FIG.

[0049] 1 and 2, the thickness t1 of the portion where the first end face 11 and the second end face 12 of the cutting insert 10 form the main body portion 14 is set to be thinner than the thickness T of the holder 30 along the axis of the clamp hole 14H. In the cutting insert 10, the thickness of the portion where the cutting portion 20 is formed is tapered so that the thickness gradually decreases in the direction from the side of the cutting portion 20 (the first cutting portion 20A and the second cutting portion 20B) toward the main body portion 14, and the thickness t2 of the cutting edge 21 satisfies t1>t2.

[0050] Hereinafter, a procedure for attaching the cutting tool 40, which is made up of the cutting insert 10 and the holder 30 of this embodiment, to the tool rest 50 and cutting the workpiece W will be described (FIGS. 3, 5, and 6).

[0051] (1) The cutting tool 40 is attached to a tool rest 50 of a machine tool that is movable in the vertical direction (X direction) and horizontal direction (Y direction) perpendicular to the rotation axis (Z axis) of the workpiece W. The machine tool (lathe, etc.) must be movable in the Y direction in addition to the usual X and Z axes.

[0052] In this embodiment, the cutting insert 10 held by the holder 30 is used such that, when the cutting tool 40 is attached to the tool post 50, the cutting insert 10 is held by the holder 30 so that the rake face 22 faces downward and the relief face 23 faces sideways.

[0053] (2) The tool post 50 to which the cutting tool 40 described in (1) above is attached is moved in the X-axis direction to put the cutting edge 21 of the cutting tool 40 into a standby state, aligned with the center height of the workpiece W. Then, the tool post 50 is fed in the Y-axis direction so as to approach the rotation axis (Z-axis) of the workpiece W rotating in the N direction, and the cutting edge 21 is moved closer to the side of the workpiece W to cut into it.

[0054] At this time, the principal component F of the cutting force accompanying cutting of the workpiece W acts upward along the longitudinal direction of the holder 30, which is disposed approximately vertically. Furthermore, because the rake face 22 faces downward, chips C discharged from the workpiece W are subjected to the action of gravity beside the workpiece W and naturally fall downward or diagonally downward. In terms of chip disposal, it is more advantageous to position the holder 30 as close to vertical as in this embodiment rather than horizontally.

[0055] Therefore, according to this embodiment, the following advantageous effects are achieved. (a) The cutting insert 10 has a rake face 22 on at least a portion of the peripheral side surface 13, the rake face 22 facing the first end face 11 and the second end face 12 in the longitudinal direction. Therefore, the principal component force F of the cutting force acting on the rake face 22 acts in the longitudinal direction of the cutting insert 10, and the cutting tool 40 including such a cutting insert 10 is less likely to bend, thereby improving its rigidity. Furthermore, in a machine tool in which the tool post 50 is arranged above the central axis of the workpiece W, chips are discharged in a direction along the longitudinal direction of the cutting insert 10 (downward), improving chip disposal. Note that many machine tools have the tool post 50 arranged on the upper side.

[0056] (b) The cutting insert 10 has rake faces 22 at both ends along the longitudinal direction of the approximately parallelogram shape. This allows the two rake faces 22 to be used in turn by reattaching the cutting insert 10 to the holder 30, which is highly economical.

[0057] When the cutting insert 10 is remounted as described above in (b), it is rotated 180 degrees relative to the mounting seat 31 of the holder 30 before being mounted.

[0058] (c) The cutting insert 10 has the uneven portion 14R provided on the peripheral side surface 13 at a portion that intersects with the short direction of the first end face 11 and the second end face 12. As a result, when the principal component force F of the cutting force acting on the rake face 22 acts in the axial direction of the holder 30, the cutting insert 10 is securely held without slippage relative to the holder 30 due to the locking action between the uneven portion 14R and the corresponding uneven locking portions 32, 33 of the holder 30.

[0059] (d) The cutting insert 10 has a rake face 22 that is set inward and away from a straight line L (FIG. 1) that circumscribes the peripheral side surface 13 along the longitudinal direction of the first end face 11. As a result, when the cutting insert 10 is attached to the holder 30 so that the longitudinal direction of the cutting insert 10 is along the longitudinal direction of the holder 30, the rake face 22 of the cutting insert 10 can be accommodated within a width dimension K (FIG. 2) of the holder 30 that intersects with the longitudinal direction. Therefore, a portion of the workpiece W can be positioned within the width dimension K of the holder 30 and cut, and even a large workpiece W can be pulled between adjacent cutting tools 40, allowing for space-saving parting-off (FIG. 3).

[0060] The force that the workpiece W exerts on the cutting insert 10 and the holder 30 is also only a compressive force, and the action of a bending force is eliminated, which is advantageous in terms of rigidity.

[0061] (e) The above (a) to (d) can be realized in the cutting tool 40.

[0062] (f) In the cutting tool 40, the cutting insert 10 is held at the tip of the holder 30 in a state in which it protrudes outward along the longitudinal direction of the holder 30, and the tip of the cutting insert 10 in the longitudinal direction has a rake face 22 facing in the longitudinal direction. Therefore, the cutting insert 10 does not protrude sideways from the holder 30 so as to approach the adjacent cutting tool 40, and the space occupied by the cutting tool 40 consisting of the holder 30 and the cutting insert 10 is reduced. Therefore, in an automatic lathe or the like equipped with many cutting tools 40 for machining complex shapes in the workpiece W, interference between the workpiece W and the tools and interference between adjacent tools can be easily avoided.

[0063] (g) In the cutting tool 40, when the holders 30 of the multiple cutting tools 40, 41 are attached to a tool rest that is provided so as to be movable in two directions perpendicular to the rotation axis (Z-axis) of the workpiece W, the rake faces 22 of the cutting inserts 10 of each cutting tool 40, 41 face downward. Therefore, by feeding the tool rest 50 vertically so that the cutting edges 21 of the cutting inserts 10 are at the center height of the workpiece W, and then feeding the tool rest horizontally (including diagonally horizontally) in this state to cut, the chips can be discharged in the direction in which they naturally fall.

[0064] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention. For example, as shown in Figure 7, the cutting insert 10 according to the present invention may be mirror-symmetric in a plan view viewed from a direction perpendicular to the first end face 11 and the second end face 12. [Industrial Applicability]

[0065] According to the present invention, the rigidity of a cutting tool having a cutting insert can be improved, and the space occupied by the cutting tool can be reduced. [Explanation of symbols]

[0066] 10 Cutting insert 11 First end surface 12 Second end face 13 Circumferential side 14 Main body 14R Uneven part 21 cutting edge 22 Rake face 23 Flank 30 Holder 31 Mounting seat 32, 33 Concave and convex locking part 40 cutting tools 50 Tool rest W Work material

Claims

1. A cutting insert having a first end surface, a second end surface, and a peripheral side surface connecting the first end surface and the second end surface and having a cutting edge, The contour shapes of the first end surface and the second end surface have a longitudinal direction and a lateral direction, The cutting insert has a rake face on at least a part of the peripheral side surface, the rake face facing each of the first end face and the second end face in the longitudinal direction.

2. The cutting insert according to claim 1 , wherein the rake face is provided on at least a part of one side and the other side of the peripheral side surface along the longitudinal direction of each of the first end face and the second end face.

3. The cutting insert according to claim 1 or 2, which has 180-degree rotational symmetry in a front view seen from a direction perpendicular to the first end face.

4. The cutting insert according to claim 3 , wherein the contour shapes of the first end surface and the second end surface are each a substantially parallelogram having a longitudinal direction and a lateral direction.

5. The cutting insert according to claim 1 , which is mirror-symmetrical in a front view seen from a direction perpendicular to the first end face.

6. The cutting insert according to any one of claims 1 to 5, further comprising at least one uneven portion provided on the peripheral side surface at a portion that intersects with each of the short directions of the first end face and the second end face and that has an uneven shape.

7. The cutting insert according to claim 1 , wherein the rake face is set inwardly and away from a straight line circumscribing the peripheral side surface along each longitudinal direction of the first end face.

8. A cutting tool comprising: the cutting insert according to claim 1; and a holder for holding the cutting insert.

9. 9. The cutting tool according to claim 8, wherein the cutting insert is held at a tip portion of the holder in a state in which the cutting insert protrudes outward along the longitudinal direction of the holder, and has a cutting surface facing in the longitudinal direction at the tip portion of the cutting insert in the longitudinal direction.

Images