Cutting Insert and Cutting Tool

Abstract

Provided are a cutting insert and a cutting tool, wherein the cutting insert can be retained by a thin retainer and can suppress reduction in the positional accuracy of the cutting edge. The cutting insert includes a first end face, a second end face, and a peripheral side face, wherein the peripheral side face is connected to the first end face and the second end face, and has a rake face, a flank face, and a cutting edge formed in a connecting area between the rake face and the flank face. The cutting insert is formed with a through hole passing through the first end face and the second end face, and includes a first abutting face that is slightly perpendicular to the central axis direction of the through hole and can abut against the retainer, a second abutting face that is slightly parallel to the central axis direction of the through hole and slightly perpendicular to the plane containing the first abutting face and can abut against the retainer, and a third abutting face that is inclined relative to the central axis direction of the through hole and can abut against the retainer. The cutting tool includes such a cutting insert.

Description

Technical Field

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

[0002] Known cutting tools are used for cutting operations such as turning, grooving, parting, and threading. These cutting tools include replaceable cutting inserts and a retainer for retaining the cutting inserts. However, if the cutting inserts are small, the force required to retain the cutting inserts is reduced. Therefore, a technique for increasing the retaining force of the cutting inserts is known.

[0003] Patent Document 1 describes a cutting tool that improves the retention strength between a cutting insert and a retainer. This cutting tool forms grooves in the retainer and cutting insert. Tightening a screw causes the grooves to abut against each other, generating a force perpendicular to the screw's central axis. This forces the cutting insert against the retainer in a direction perpendicular to the screw's central axis, securely holding the cutting insert.

[0004] Patent Document 2 describes a cutting insert having four cutting edges and four abutment surfaces. According to this cutting tool, when cutting with one cutting edge, three of the four abutment surfaces abut against the holder, thereby firmly holding the cutting insert on the holder.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: (International Patent Application Entering Japan) Japanese Patent Publication No. 2003-503218

[0008] Patent Document 2: (International Patent Application Entering Japan) Japanese Patent Application No. 2013-540058

[0009] Technical issues

[0010] However, in the cutting insert described in Patent Document 1, since the groove is formed in the thread tightening direction, it is difficult to improve the position accuracy of the cutting edge in the thread tightening direction. Therefore, in order to maintain the position accuracy of the cutting edge, the shape accuracy of the cutting insert must be improved.

[0011] In addition, among the cutting insert of patent document 1, its cutting edge has the abutment surface of constraint cutting insert around. Therefore, when one of the cutting edges of the cutting insert with multiple cutting edges is damaged, the abutment surface around the cutting edge is also damaged, thereby being difficult to reuse other cutting edges.

[0012] In addition, in the cutting inserts described in Patent Documents 1 and 2, in order to support the peripheral side surfaces of the cutting insert, the cutting insert needs to be held in a retainer having a thickness greater than the width of the cutting insert. Therefore, it is necessary to use a plurality of cutting inserts of different sizes according to the thickness of the retainer.

[0013] Therefore, an object of the present invention is to provide a cutting insert and a cutting tool that can use the cutting edge even if the cutting edge is damaged, can be held in a thin holder, or can suppress reduction in positional accuracy of the cutting edge. Summary of the Invention

[0014] The present application discloses a cutting insert. The cutting insert includes a first end face, a second end face, and a peripheral side face, the peripheral side face being connected to the first end face and the second end face and having a rake face, a flank face, and a cutting edge formed in a connecting region between the rake face and the flank face. The cutting insert is a longitudinal cutting insert having a through hole extending through the first end face and the second end face, the cutting insert including a first abutting face that is slightly perpendicular to the central axis of the through hole and can abut against a retainer, a second abutting face that is slightly parallel to the central axis of the through hole and slightly perpendicular to a plane containing the first abutting face and can abut against the retainer, and a third abutting face that is inclined relative to the central axis of the through hole and can abut against the retainer.

[0015] The cutting blade includes a first end and a second end, the first end corresponds to one end side of the through hole in the direction of the central axis, and the first end face is provided on the first end, the second end corresponds to the other end side of the through hole in the direction of the central axis, and the second end face is provided on the second end, the second end includes a convex portion protruding in a direction away from the first end face, and the third abutting surface can be provided on the inclined surface of the convex portion.

[0016] The second end portion includes at least two protrusions, one of the protrusions has an inclined surface forming one of the third abutting surfaces, and another of the protrusions has an inclined surface forming another third abutting surface opposite to the one third abutting surface.

[0017] The one third abutting surface and the other third abutting surface may be formed symmetrically with respect to a first imaginary plane that passes through the central axis of the through hole and is perpendicular to a first direction corresponding to the longitudinal direction of the cutting insert.

[0018] The one convex portion and the other convex portion may be formed symmetrically with respect to a second imaginary plane that passes through the central axis of the through hole and is perpendicular to a second direction corresponding to a width direction of the cutting insert.

[0019] However, the first direction and the second direction are perpendicular to the central axis of the through hole, and the first direction and the second direction are perpendicular to each other.

[0020] The one third abutting surface is formed so that the further away from the center axis along the second direction, the greater the distance from the first imaginary plane is, and the other third abutting surface is formed so that the further away from the center axis along the second direction, the greater the distance from the first imaginary plane is.

[0021] The cutting blade includes a peripheral side surface portion connected to the first end portion and the second end portion and provided with the peripheral side surface. The peripheral side surface portion may include at least two standing portions protruding in a direction away from the second imaginary plane. The peripheral side surface includes at least two second abutment surfaces. One second abutment surface can be provided on the surface of one standing portion, and another second abutment surface can be provided on the surface of another standing portion.

[0022] The cutting edge is formed at a front end portion in a first direction corresponding to the longitudinal direction of the cutting blade;

[0023] A second abutment surface is formed in an area where the front end side of the cutting edge exists with the central axis as a boundary in the first direction, and in an area where the lower end side of the cutting edge does not exist with the central axis as a boundary in a second direction corresponding to the width direction of the cutting insert;

[0024] There is no area on the base end side of the cutting edge with the central axis as a boundary in the first direction, and another second abutment surface is formed in the area on the lower end side;

[0025] A first third abutment surface is formed in a region on the base end side and in a region on the upper end side of the cutting edge with respect to the central axis in the second direction;

[0026] A second third abutting surface is formed in the area on the base end side and in the area on the lower end side;

[0027] A third abutting surface is formed in the region of the front end side and in the region of the lower end side;

[0028] A fourth third abutting surface is formed in the region on the front end side and in the region on the upper end side.

[0029] The through hole may be formed to be symmetrical about 180 degrees of rotation with respect to the central axis of the through hole.

[0030] The present application discloses a cutting tool comprising any one of the cutting inserts described above and a holder for holding the cutting insert. The holder may include a seat surface abutting the first abutting surface of the cutting insert, and wall surfaces abutting the one second abutting surface, the other second abutting surface, and the first third abutting surface of the cutting insert, respectively.

[0031] The present application discloses a cutting tool comprising any of the cutting inserts described above and a retainer for retaining the cutting insert. The retainer may be a retainer different from the retainer described above. The retainer may include a seat surface abutting the first abutting surface of the cutting insert, and wall surfaces abutting the first, second, and third abutting surfaces of the cutting insert, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a perspective view of a cutting insert according to one embodiment.

[0033] Figure 2 These are a top view, a front view, a rear view, and a right side view of a cutting insert according to one embodiment.

[0034] Figure 3 This is an enlarged perspective view of a clamping portion of a cutting insert according to one embodiment.

[0035] Figure 4 This is an enlarged perspective view of a cutting tool according to one embodiment.

[0036] Figure 5 This is an enlarged perspective view of a cutting tool according to one embodiment.

[0037] Description of main component symbols

[0038] Cutting insert 10

[0039] Through hole 10H

[0040] First cutting portion 20A

[0041] Second cutting portion 20B

[0042] Clamping portion 30

[0043] First end portion 40

[0044] First end surface 40S

[0045] Second end portion 50

[0046] Projection 50A

[0047] Reference surface 50A1

[0048] Inclined surface 50A31

[0049] Inclined surface 50A32

[0050] Projection 50B

[0051] Reference surface 50B1

[0052] Inclined surface 50B31

[0053] Inclined surface 50B32

[0054] Bottom 50G

[0055] Second end surface 50S

[0056] Standing section 70A1

[0057] Standing section 70A2

[0058] Standing section 70B1

[0059] Standing part 70B2

[0060] First retainer 80

[0061] Second retainer 90

[0062] First cutting tool 180

[0063] Second cutting tool 190 DETAILED DESCRIPTION

[0064] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiments are examples for explaining the present invention, and the present invention is not limited to these embodiments.

[0065] Figure 1 It is a perspective view of the cutting insert 10 according to this embodiment. Figure 2 (A), (B), (C) and (D) are respectively a top view, a front view, a rear view and a right side view of the cutting insert 10. Figure 3 It is an enlarged perspective view of a portion of the cutting insert 10 including the second end surface 50S.

[0066] As an example, the cutting insert 10 of the present embodiment is a cutting insert for cutting to separate a workpiece in the following manner, that is, the cutting edge is pressed against the rotating workpiece in the radial direction (a direction perpendicular to the rotation axis of the workpiece) to remove unnecessary parts of the workpiece. However, the present invention is not limited to this, and for example, it can be widely applied to cutting inserts for turning processing, other cutting inserts and cutting tools that cut the outer diameter of the workpiece by pressing the cutting edge in a direction parallel to the rotation axis of the workpiece. For example, the present invention is applicable not only to cutting inserts and cutting tools for turning processing, but also to cutting inserts and cutting tools for milling processing that can perform hole processing, etc.

[0067] As shown in these drawings, the cutting insert 10 has a first end surface 40S, a second end surface 50S, and a peripheral side surface 70S connected to the first end surface 40S and the second end surface 50S. The cutting insert 10 is formed with a through hole 10H penetrating the first end surface 40S and the second end surface 50S.

[0068] like Figure 2 As shown in FIG. 2B , in the main view (front view), the cutting insert 10 is formed into a parallelogram. Hereinafter, the length direction of the cutting insert 10 in the main view is sometimes referred to as the first direction DR1, and the width direction is sometimes referred to as the second direction DR2. In addition, in the first direction DR1, the direction in which the first cutting edge 20A1 is formed is sometimes referred to as the front of the first direction DR1, and the direction in which the second cutting edge 20B1 is formed is sometimes referred to as the rear of the first direction DR1. In the second direction DR2, the direction in which the first cutting edge 20A1 is formed is sometimes referred to as the top of the second direction DR2, and the direction in which the second cutting edge 20B1 is formed is sometimes referred to as the bottom of the second direction DR2. The first direction DR1 is perpendicular to the second direction DR2 and the central axis AX direction of the through hole 10H, and the second direction DR2 is perpendicular to the first direction DR1 and the central axis AX direction. In addition, in the central axis AX direction of the through hole 10H, the direction in which the first end face 40S is formed is sometimes referred to as the outside of the central axis AX direction, and the direction in which the second end face 50S is formed is sometimes referred to as the inside of the central axis AX direction.

[0069] For example, the cutting insert 10 has a dimension of 30 mm or less in the first direction DR1, 10 mm or less in the second direction DR2, and 5 mm or less in the direction of the central axis AX. As described later, the cutting insert 10 is configured to be retained not only in a holder of a conventional size but also in a compact holder.

[0070] As shown in the same figure, in the front view (front view), the cutting insert 10 is formed symmetrically when rotated 180 degrees with respect to the central axis AX. Hereinafter, in the first direction DR1, the portion corresponding to the center of the cutting insert 10 is referred to as the clamping portion 30, the portion on the front side of the clamping portion 30 in the first direction DR1 is referred to as the first cutting portion 20A, and the portion on the base side of the clamping portion 30 in the first direction DR1 is referred to as the second cutting portion 20B.

[0071] The clamping portion 30 (holding portion) holds the cutting insert 10 in a holder (described later). The first cutting portion 20A is used to cut the workpiece. The first cutting portion 20A is located forward of the clamping portion 30 in the first direction DR1. A first cutting edge 20A1, serving as a front cutting edge, is formed at the forward end portion in the first direction DR1 (near the acute angle vertex of the parallelogram).

[0072] The second cutting portion 20B is a portion for cutting the workpiece. It is located rearward of the clamping portion 30 in the first direction DR1, which is opposite the first cutting portion 20A. A second cutting edge 20B1, serving as a front cutting edge, is formed at the rear end in the first direction DR1 (near the acute angle vertex of the parallelogram).

[0073] Since the cutting insert 10 is formed as a reference rotation 180 degrees symmetry with the central axis AX, after the first cutting edge 20A1 is worn, the second cutting edge 20B1 can be used as long as the cutting insert 10 is rotated 180 degrees. In addition, since the cutting insert 10 is maintained in the retainer by the clamping portion 30, even if the cutting edge of one cutting portion is damaged, the cutting edge of another cutting portion can be used.

[0074] Hereinafter, the configuration of the clamping portion 30 will be described in detail.

[0075] As described above, the clamping portion 30 is used to retain the cutting insert 10 in the retainer and includes a first end face 40S, a second end face 50S, and a portion of the peripheral side face 70S. As will be described later, the cutting insert 10 is retained in the retainer by inserting an external screw through the first end face 40S into the through hole 10H, engaging the external threads of the external screw with the internal threads formed on the retainer. The head of the external screw presses against the first end face 40S, pressing the second end face 50S against the retainer.

[0076] like Figure 2 As shown in A, the clamping portion 30 includes a first end portion 40 corresponding to one end side on the outside of the central axis AX direction, a second end portion 50 corresponding to the other end side on the inside of the central axis AX direction, and a peripheral side portion 70 connecting the first end portion 40 and the second end portion 50.

[0077] The first end surface 40S is provided on the surface of the first end portion 40. The first end surface 40S is a surface substantially perpendicular to the direction of the central axis AX and has a surface to be pressed by the head of the male screw.

[0078] The second end surface 50S is provided on the surface of the second end portion 50. The second end portion 50 includes a groove bottom surface 50G recessed toward the first end surface 40S, and two convex portions 50A and 50B protruding away from the first end surface 40S.

[0079] The bottom surface 50G of the groove portion extends in the second direction DR2 at the center of the clamping portion 30 in the first direction DR1 so as to be sandwiched between the two protrusions 50A and 50B. The bottom surface 50G corresponds to the surface of the second end surface 50S that is located closest to the first end surface 40S. The bottom surface 50G is arranged to be slightly perpendicular to the direction of the central axis AX. A through hole 10H is formed in the center of the bottom surface 50G in the second direction DR2. Figure 2 As shown in FIG. 3 , in this embodiment, the groove width of the bottom surface 50G in the first direction DR1 is widest at both ends in the second direction DR2 connected to the peripheral side surface 70S, and gradually narrows as it moves away from the peripheral side surface 70 and approaches the through hole 10H, and is connected to the through hole 10H.

[0080] As shown in the same figure, the protrusion 50A has a reference surface 50A1 (an example of a "first contact surface"), two inclined surfaces 50A31 (an example of a "third contact surface") and 50A32 (an example of a "third contact surface"). The protrusion 50A is provided forward of the groove in the first direction DR1.

[0081] The reference surface 50A1 is a surface corresponding to the top surface of the protrusion 50A, and is a surface located in the second end face 50S and in the surface of the cutting insert 10 at a position farthest from the first end face 40S in the direction of the center axis AX. Since the reference surface 50A1 is arranged to be slightly perpendicular to the direction of the center axis AX, the reference surface 50A1 is brought into contact with the retaining frame, and the cutting insert 10 can be positioned with high precision in the direction of the center axis AX. In addition, since the reference surface 50A1 of this embodiment is formed to be larger than the diameter of the through hole 10H in the second direction DR2, it can be stably retained on the retaining frame. In addition, the reference surface 50A1 is symmetrically arranged with respect to a second imaginary plane IP2 passing through the center axis AX, parallel to the first direction DR1, and perpendicular to the second direction DR2. This structure also helps to stably retain the cutting insert on the retaining frame.

[0082] The inclined surface 50A31 and the inclined surface 50A32 are side surfaces of the convex portion 50A, and are provided between the reference surface 50A1 and the bottom surface 50G of the groove portion.

[0083] In the end view (rear view, Figure 2 In FIG. 3 , the inclined surface 50A31 is positioned forward in the first direction DR1 and upward in the second direction DR2 relative to the central axis AX. The inclined surface 50A31 is positioned so that its normal faces rearward in the first direction DR1 and upward in the second direction DR2, and faces inward in the direction of the central axis AX when viewed from the side perpendicular to the central axis AX. In other words, the inclined surface 50A31 is positioned so that its normal is inclined relative to the central axis AX, whether viewed from the rear side parallel to the central axis AX or from the side perpendicular to the central axis AX.

[0084] In order to maintain such normals, in the end view (back view, Figure 2 In C), the inclined surface 50A31 is formed so that the distance from the first imaginary plane IP1 increases as it moves away from the central axis AX1 in the upper direction of the second direction DR2. However, the inclined surface 50A31 may be a flat surface or a curved surface.

[0085] The convex portion 50A is formed symmetrically with respect to the second imaginary plane IP2, so the end view (rear view, Figure 2 In FIG. 3 , inclined surface 50A32 is positioned forward in the first direction DR1 and downward in the second direction DR2 relative to central axis AX. Inclined surface 50A31 is positioned so that its normal faces rearward in the first direction DR1 and downward in the second direction DR2, and faces inward in the direction of central axis AX when viewed from the side facing peripheral side surface 70S. In other words, inclined surface 50A32 is positioned so that its normal faces incline relative to central axis AX, whether viewed from the rear as viewed parallel to central axis AX or from the side as viewed perpendicular to central axis AX.

[0086] The convex portion 50B has a reference surface 50B1 (an example of a "first abutting surface"), two inclined surfaces 50B31 (an example of a "third abutting surface") and 50B32 (an example of a "third abutting surface"). The convex portion 50B is arranged behind the bottom surface 50G of the groove portion in the first direction DR1. The first imaginary plane IP1 passes through the central axis AX, is perpendicular to the first direction DR1, and is parallel to the second direction DR2. The convex portion 50B and the convex portion 50A are formed symmetrically with respect to the first imaginary plane IP1. Therefore, by appropriately replacing the relevant description of the above-mentioned convex portion 50A with the relevant description of the reference surface 50B1, the inclined surface 50B31 and the inclined surface 50B32, the detailed description is omitted. That is, the inclined surface 50B31 is formed with its normal facing the front of the first direction DR1, the top of the second direction DR2, and the inside of the central axis AX direction, and the inclined surface 50B32 is formed with its normal facing the front of the first direction DR1, the bottom of the second direction DR2, and the inside of the central axis AX direction. This In addition, inclined surfaces 50B31 and 50B32 are formed symmetrically with respect to first imaginary plane IP1, respectively, relative to inclined surfaces 50A31 and 50A32. Therefore, inclined surfaces 50A31 (50A32) and 50B31 (50B32) are opposed to each other and symmetrically formed relative to first imaginary plane IP1. In the end view, they are formed such that, as shown below, their distance from first imaginary plane IP1 increases as they move away from central axis AX in the upper (lower) direction of the second direction. Therefore, in the upper (lower) direction of the second direction, the distance between inclined surfaces 50A31 (50A32) and 50B31 (50B32) increases as they move away from central axis AX. Furthermore, the distance between inclined surfaces 50A31 (50A32) and 50B31 (50B32) increases as they move away from the bottom surface 50G of the groove portion and toward the outside of the central axis AX.

[0087] In other words, the normal lines of the four inclined surfaces provided on the second end surface 50S, namely, the inclined surface 50A31, the inclined surface 50A32, the inclined surface 50B31, and the inclined surface 50B32, are all close to the first imaginary plane IP1 and away from the second imaginary plane IP2, and are oriented in a direction away from the first end surface 40S. In addition, the end view (rear view, Figure 2 C), it is provided inside the peripheral side surface 70S.

[0088] Rear view as viewed from the direction facing the second end surface 50S ( Figure 2In FIG. C), a straight line approximating the extending direction of the inclined surface 50A31 does not pass through the central axis AX and has an angle of, for example, 40 to 60 degrees relative to the first imaginary plane IP1. Furthermore, when cut along a cross section perpendicular to the straight line, the inclined surface 50A31 has an oblique angle of, for example, 40 to 60 degrees relative to the bottom surface 50G of the groove portion. The other three inclined surfaces have the same structure.

[0089] The structure of the peripheral side surface 70S will be described in detail later. The peripheral side surface 70S is a surface connected to the first end surface 40S and the second end surface 50S, and has a surface facing a direction perpendicular to the central axis AX direction. The surface of the peripheral side surface 70S facing upward in the second direction DR2 of the first cutting portion 20A has a rake face 20A2 ( Figure 2 A), the surface facing forward in the first direction DR1 has a flank surface 20A3 relative to the first cutting edge 20A1. In addition to the front cutting edge, the first cutting portion 20A is further provided with two transverse cutting edges, namely, a transverse cutting edge 20A4 and a transverse cutting edge 20A5.

[0090] The second cutting portion 20B is formed symmetrically with the first cutting portion 20A, rotated 180 degrees about the central axis AX. Therefore, on the peripheral side surface 70S, the surface of the second cutting portion 20B facing downward in the second direction DR2 has a rake face 20B2 relative to the second cutting edge 20B1, and the surface facing rearward in the first direction DR1 has a flank face 20B3 relative to the second cutting edge 20B1. Furthermore, in addition to the front cutting edge, the second cutting portion 20B is also provided with two transverse cutting edges: a transverse cutting edge 20B4 and a transverse cutting edge 20B5.

[0091] like Figure 2As shown in FIG. 2B , the surface of the peripheral side surface 70S above the second direction DR2 protrudes slightly upward in the second direction DR2 at the front end and rear end of the clamping portion 30 in the first direction DR1, respectively. Similarly, the surface of the peripheral side surface 70S below the second direction DR2 protrudes slightly downward in the second direction DR2 at the front end and rear end of the clamping portion 30 in the first direction DR1, respectively. These four protruding portions are referred to as the standing portion 70A1, standing portion 70B1, standing portion 70A2, and standing portion 70B2. The top surface 70A1S (an example of a "second abutting surface"), top surface 70B1S (an example of a "second abutting surface"), top surface 70A2S (an example of a "second abutting surface"), and top surface 70B2S (an example of a "second abutting surface") of each standing portion are slightly parallel to the central axis AX. In this embodiment, these top surfaces extend along the central axis AX so as to connect to the first end surface 40S and the second end surface 50S. Furthermore, recesses are provided in the gaps between the standing portions 70A1 (standing portion 70A2) and 70B1 (standing portion 70B2). These top surfaces of the clamping portion 30 are located at the positions furthest from the second imaginary plane IP2 in the second direction DR2. Therefore, these top surfaces can serve as contact surfaces against the retainer.

[0092] like Figure 2 As shown in FIG. 3 , the cutting insert 10 is divided into four regions by the first imaginary plane IP1 and the second imaginary plane IP2. The region where the front end of the first cutting edge 20A1 is located in the first direction DR1 and the region where the upper end of the first cutting edge 20A1 is located in the second direction DR2 are the first region ( Figure 2 C), an area on the front end side of the first cutting edge 20A1 in the first direction DR1 and an area on the lower end side of the first cutting edge 20A1 in the second direction DR2 is not provided as the second area ( Figure 2 C), an area on the base end side of the first cutting edge 20A1 in the first direction DR1 and an area on the lower end side of the first cutting edge 20A1 in the second direction DR2 is provided as a third area ( Figure 2 C), an area on the base end side of the first cutting edge 20A1 does not exist in the first direction DR1 and an area on the upper end side of the first cutting edge 20A1 exists in the second direction DR2 as a fourth area ( Figure 2 C), the top surface 70A1S and the inclined surface 50A31 exist in the first area, the top surface 70A2S and the inclined surface 50A32 exist in the second area, the top surface 70B2S and the inclined surface 50B32 exist in the third area, the top surface 70B1S and the inclined surface 50B31 exist in the fourth area, and each inclined surface is arranged at a position close to the central axis AX relative to each top surface.

[0093] As described above, the cutting insert 10 comprises two first abutment surfaces (reference surface 50A1 and reference surface 50B1), four second abutment surfaces (top surfaces 70A1S to 70B2S), and four third abutment surfaces (inclined surfaces 50A31 to 50B32). As described later, by using different combinations of these abutment surfaces, the cutting insert 10 can be maintained on various types of retainers.

[0094] Figure 4 A is a perspective view of a first retainer 80 capable of retaining a cutting insert 10. Figure 4 B is an enlarged perspective view of the first cutting tool 180 including the cutting insert 10 and the first holder 80 that holds the cutting insert 10 .

[0095] As shown in the same figure, the thickness of the first holder 80 is equal to or slightly larger than the length of the cutting insert 10 in the second direction DR2 .

[0096] The first holder 80 includes a seat surface 80A that contacts the reference surfaces 50A1 and 50B1, an internal thread 80A1 formed on the seat surface 80A, and two walls 80B1 and 80B2 that protrude perpendicularly to the seat surface 80A. The wall 80B1 and the wall 80B2 are spaced apart with the internal thread 80A1 interposed therebetween.

[0097] The wall portion 80B1 and the wall portion 80B2 are arranged to protrude from the seat surface 80A in a direction corresponding to the outer side in the direction of the central axis AX when the cutting insert 10 is held. The wall portion 80B1 (wall portion 80B2) has a wall surface that abuts or approaches and is opposite to the inclined surface 50A31 (inclined surface 50A32) when entering the groove portion to hold the cutting insert 10, and a wall surface that abuts or approaches and is opposite to the inclined surface 50B31 (inclined surface 50B32). In order to abut or approach and be opposite to the desired position, when the wall portion 80B1 (wall portion 80B2) is arranged, the surfaces of the corners provided on the wall portion 80B1 (wall portion 80B2) abut or approach and are opposite to the inclined surface 50A31 (inclined surface 50A32) and the inclined surface 50B31 (inclined surface 50B32), respectively.

[0098] Through such a structure, when the first retaining frame 80 holds the cutting blade 10 and performs processing, at least three of the four third abutment surfaces (inclined surfaces 50A31~50B32) can be supported by the first retaining frame 80, for example, the inclined surface 50B31, the inclined surface 50A32 and the inclined surface 50B32.

[0099] When cutting using the first cutting edge 20A1 of this cutting insert 10, an external screw S is inserted from the first end face 40S into the through hole 10H and screwed into the internal thread 80A1 of the first retainer 80 to tighten the external screw S. As a result, the head of the external screw S presses against the enlarged diameter portion (the annular portion) provided on the inner wall of the through hole 10H, and the reference surfaces 50A1 and 50B1 of the second end face 50S press against the seat surface 80A. The force applied inward toward the center axis AX by the external screw S and the force applied outward toward the center axis AX as a reaction force to the reference surfaces 50A1 and 50B1 are the primary securing elements for retaining the cutting insert 10. The cutting insert 10 of this embodiment further utilizes at least three inclined surfaces, namely, the inclined surface 50A32, the inclined surface 50B32, and the inclined surface 50B31, as restraining surfaces, thereby preventing the cutting insert 10 from rotating about the center axis AX.

[0100] In order to appropriately contact the inclined surface 50A32 and the inclined surface 50B32 with the wall portion 80B2 , the threaded hole axis of the internal thread 80A1 and the screw axis of the external screw S may be displaced (by thread amount).

[0101] Furthermore, to ensure that the inclined surface 50B31 and the wall portion 80B1 are in proper contact, the external screw S (and the internal thread 80A1 screwed therewith) may be a left-hand screw. By using a left-hand screw, the frictional force generated between the external screw S and the internal thread 80A1 acts in a direction that causes the inclined surface 50B31 to contact the wall portion 80B1, thereby ensuring that the wall portion 80B1 is in proper contact with the inclined surface 50B31.

[0102] As a result, at least three inclined surfaces, namely the inclined surface 50A32, the inclined surface 50B32 and the inclined surface 50B31, are used as constraint surfaces to prevent the cutting blade 10 from rotating around the central axis AX. That is, forces in the opposite direction to the normal lines act on these inclined surfaces. Therefore, the force on the second end surface 50S of the cutting blade 10 is not only a force in the direction toward the first end surface 40S (outward in the direction of the central axis AX), but also a force in the direction perpendicular to the direction of the central axis AX (for example, in the length direction, a force in the direction away from the first imaginary plane IP1 is generated on at least three inclined surfaces, namely the inclined surface 50B32, the inclined surface 50A32 and the inclined surface 50B31 (stress pulling the cutting blade 10 in the length direction), and in the width direction, a force in the direction close to the second imaginary plane IP2 is generated on at least three inclined surfaces, namely the inclined surface 50B32, the inclined surface 50A32 and the inclined surface 50B31 (stress compressing the cutting blade 10 in the width direction). Therefore, the cutting insert 10 can be firmly held in a direction perpendicular to the center axis AX direction. Since the inclined surface 50B31 and the inclined surface 50A32 are provided, the rotation of the cutting insert 10 around the center axis AX due to the rotational torque generated during turning can be suppressed. In addition, since the first retaining frame 80 holds the cutting insert 10 without contacting the peripheral side surface 70S of the cutting insert 10, the thickness of the first retaining frame 80 can be reduced, thereby providing a first cutting tool 180 with a thin thickness. In addition, by making the reference surface 50A1 and the reference surface 50B1 contact the seat surface 80A, the cutting edge position accuracy in the thickness direction (center axis AX direction) of the cutting insert 10 can be improved.

[0103] Figure 5 A is a perspective view of the second retainer 90 capable of holding the cutting insert 10. Figure 5 B is an enlarged perspective view of the second cutting tool 190 including the cutting insert 10 and the second holder 90 that holds the cutting insert 10 .

[0104] As shown in the same figure, the thickness of the second holder 90 is greater than the length of the cutting insert 10 in the second direction DR2.

[0105] The second holder 90 includes a seat surface 90A for contacting the reference surfaces 50A1 and 50B1, an internal thread 90A1 formed on the seat surface 90A, and two walls 90B1 and 90B2 protruding perpendicularly to the seat surface 90A. The wall 90B1 and the wall 90B2 are spaced apart with the internal thread 90A1 interposed therebetween.

[0106] The wall portion 90B1 and the wall portion 90B2 are provided so as to protrude from the seat surface 90A in a direction corresponding to the outer side in the direction of the central axis AX when the cutting insert 10 is held. The wall portion 90B1 includes a wall surface that abuts, approaches, and faces the inclined surface 50A31 when the cutting insert 10 is held, and a wall surface that abuts, approaches, and faces the inclined surface 50B31. To achieve abutment, approach, and facing the desired position, the corner surfaces of the wall portion 90B1 are arranged so as to abut, approach, and face the inclined surface 50A31 and the inclined surface 50B31, respectively.

[0107] On the other hand, the wall portion 90B2 has a flush wall surface that abuts against the top surface 70A2S of the standing portion 70A2 and the top surface 70B2S of the standing portion 70B2 without intruding into the groove portion of the cutting insert 10 when holding the cutting insert 10. In addition, since a recess is provided in the gap between the standing portions 70A2 and 70B2, the gap portion does not abut against the wall surface of the wall portion 90B2.

[0108] When cutting using the first cutting edge 20A1 of this cutting insert 10, an external screw S is inserted into the through-hole 10H from the first end face 40S and screwed into the internal thread 90A1 of the second retainer 90 to tighten the external screw S. As a result, the head of the external screw S presses against the enlarged diameter portion (the annular portion) provided on the inner wall of the through-hole 10H, and the reference surface 50A1 and the reference surface 50B1 of the second end face 50S are pressed against the seat surface 90A. At this time, the wall surface of the wall portion 90B1 at least abuts the inclined surface 50B31. A force in the direction opposite to the normal acts on the inclined surface 50B31. Therefore, a force in the direction toward the first end face 40S (outward in the direction of the central axis AX) acts on the second end face 50S of the cutting insert 10, generating a large stress between the head of the external screw S and the external screw S. In addition, in the longitudinal direction, a force is generated in a direction away from the first imaginary plane IP1 (stress that pulls the cutting blade 10 in the longitudinal direction), and in the width direction, a force is generated in a direction close to the second imaginary plane IP2 (stress that compresses the cutting blade 10 in the width direction). Due to the force generated in the width direction, the top surface 70A2S of the standing portion 70A2 and the top surface 70B2S of the standing portion 70B2 are pressed against the wall surface of the wall portion 90B2. Therefore, the cutting blade 10 can be firmly held on the second retaining frame 90. In particular, since the inclined surface 50B31 is provided, it is possible to suppress the cutting blade 10 from rotating around the center axis AX due to the rotational torque generated during turning. In addition, by making the reference surface 50A1 and the reference surface 50B1 abut against the seat surface 90A, the cutting edge position accuracy of the cutting blade 10 in the thickness direction (center axis AX direction) can be improved.

[0109] As described above, the cutting insert 10 can be held by both the first and second retainers 80, 90. Therefore, when there is sufficient space for the cutting insert 10 in the second direction DR2, the cutting insert 10 can be held in the second retainer 90 during machining. In this case, since the retainer thickness is ensured, the cutting insert 10 can be securely clamped in the second retainer 90. On the other hand, when there is insufficient space for the cutting insert 10 in the second direction DR2, the cutting insert 10 can be held in the first retainer 80 during machining.

[0110] Here, by integrally molding in a compacted state, the four inclined surfaces 50A31 to 50B32 of the cutting insert 10 and the top surfaces 70A1S to 70B2S of the standing portions 70A1 to 70B2 are formed simultaneously. Manufacturing the cutting insert 10 in this manner can improve the accuracy of the relative positional relationship between the inclined surfaces and the standing portions. Therefore, for example, compared to the case where the top surfaces 70A1S to 70B2S are formed by cutting, the correlation between the variation in the height of the cutting edge position relative to the top surfaces 70A1S to 70B2S and the variation in the height of the cutting edge position relative to the inclined surfaces 50A31 to 50B32 can be improved. Therefore, when the cutting insert 10 is held by the first retaining frame 80 and the second retaining frame 90, the cutting edge position accuracy in the second direction DR2 can be maintained at a certain level. In particular, by providing a recess between the top surfaces, the positional accuracy can be further improved.

[0111] Furthermore, the present invention is susceptible to various modifications without departing from its main purpose. For example, the present invention can be applied to other types of cutting inserts having a clamping portion at the center in the first direction DR1 and cutting edges at two locations diagonally opposite the central axis AX. Furthermore, within the ordinary creative capabilities of those skilled in the art, some components of one embodiment may be replaced or removed with other known components.

Claims

1. A cutting insert comprising a first end face, a second end face, and a peripheral side face, wherein the peripheral side face is connected to the first end face and the second end face and has a rake face, a flank face, and a cutting edge, wherein the cutting edge is formed in a connecting region between the rake face and the flank face, and wherein the cutting insert has a through hole extending through the first end face and the second end face. The cutting insert includes a first abutment surface that is slightly perpendicular to the central axis of the through hole and can abut against a retainer, a second abutment surface that is slightly parallel to the central axis of the through hole and slightly perpendicular to a plane containing the first abutment surface and can abut against the retainer, and a third abutment surface that is inclined relative to the central axis of the through hole and can abut against the retainer; The cutting insert includes a first end portion and a second end portion, the first end portion corresponds to one end side of the through hole in the direction of the central axis, and the first end portion is provided with the first end surface, the second end portion corresponds to the other end side of the through hole in the direction of the central axis, and the second end portion is provided with the second end surface, the second end portion includes a convex portion protruding in a direction away from the first end surface, the convex portion has a reference surface, the reference surface is the first abutting surface, and the third abutting surface is provided on an inclined surface of the convex portion; The second end portion includes at least two protrusions, one of the protrusions has an inclined surface forming a third abutting surface, and another protrusion has an inclined surface forming another third abutting surface opposite to the one third abutting surface; The one convex portion and the other convex portion are respectively formed symmetrically with respect to a second imaginary plane, the second imaginary plane passing through the central axis of the through hole and being perpendicular to a second direction corresponding to the width direction of the cutting insert; The cutting insert includes a peripheral side surface portion connected to the first end portion and the second end portion and provided with the peripheral side surface, The peripheral side surface includes at least two standing portions protruding in a direction away from the second imaginary plane, The peripheral side surface includes at least two second abutting surfaces, One of the second abutting surfaces is provided on a surface of one of the standing portions, Another second abutting surface is provided on the surface of another standing portion.

2. The cutting insert according to claim 1, wherein The one third abutting surface and the other third abutting surface are formed symmetrically with respect to a first imaginary plane that passes through the central axis of the through hole and is perpendicular to a first direction corresponding to the longitudinal direction of the cutting insert.

3. The cutting insert according to claim 2, wherein At least two of the protrusions include two protrusions; the two protrusions are arranged opposite to each other, and two third abutting surfaces are formed on the inclined surface of one of the protrusions; another two third abutting surfaces are formed on the inclined surface of the other protrusion, and the two third abutting surfaces and the other two third abutting surfaces are respectively arranged opposite to each other; the first curved surface is connected between the two third abutting surfaces, and the second curved surface is connected between the other two third abutting surfaces; the open end of the first curved surface is arranged facing the open end of the second curved surface.

4. The cutting insert according to claim 2, wherein The one third abutting surface is formed so that the further away from the central axis in the second direction, the greater the distance from the first imaginary plane. The other third abutting surface is formed so that the further away from the central axis along the second direction, the greater the distance from the first imaginary plane.

5. The cutting insert according to claim 1, wherein The cutting edge is formed at a front end portion in a first direction corresponding to the longitudinal direction of the cutting blade; A second abutment surface is formed in an area where the front end side of the cutting edge exists with the central axis as a boundary in the first direction, and in an area where the lower end side of the cutting edge does not exist with the central axis as a boundary in a second direction corresponding to the width direction of the cutting insert; There is no area on the base end side of the cutting edge with the central axis as a boundary in the first direction, and another second abutment surface is formed in the area on the lower end side; A first third abutment surface is formed in a region on the base end side and in a region on the upper end side of the cutting edge with respect to the central axis in the second direction; A second third abutting surface is formed in the area on the base end side and in the area on the lower end side; A third abutting surface is formed in the region of the front end side and in the region of the lower end side; A fourth third abutting surface is formed in the region on the front end side and in the region on the upper end side.

6. The cutting insert according to any one of claims 1 to 5, wherein The through hole is symmetrical with respect to a rotation of 180 degrees with respect to the central axis of the through hole.

7. A cutting tool comprising the cutting insert according to claim 5 and a holder for holding the cutting insert, The holder includes a seat surface that contacts the first contact surface of the cutting insert, and wall surfaces that contact the one second contact surface, the other second contact surface, and the first third contact surface of the cutting insert, respectively.

8. A cutting tool comprising the cutting insert according to claim 5 and a holder for holding the cutting insert, The retainer includes a seat surface that contacts the first contact surface of the cutting insert, and wall surfaces that contact the first, second, and third third contact surfaces of the cutting insert, respectively.

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