WO2015129770A1

WO2015129770A1 - Cutting insert, tool body, and cutting tool

Info

Publication number: WO2015129770A1
Application number: PCT/JP2015/055480
Authority: WO
Inventors: 哲司小宮山
Original assignee: 株式会社タンガロイ
Priority date: 2014-02-26
Filing date: 2015-02-25
Publication date: 2015-09-03
Also published as: JP6052712B2; JPWO2015129770A1

Abstract

　The present invention pertains to a cutting insert (1) provided with: at least one cutting blade (2g) formed at the intersection ridgeline section of a first end face (2) among two end faces, and a circumferential side face (4); and a hole (5) passing through the two end faces. The hole (5) has a first hole section (5a) and a second hole section (5b). The second hole section is positioned closer than the first hole section to a first end face, on which the relevant cutting blade is formed, in the direction of the center line axis (A) of the hole (5), and opens on the first end face. The second hole section has a larger inner dimension than the first hole section. The second hole section has a first inner face section and a second inner face section in the circumferential direction of the hole. The first inner face section is closer to the center axis line than the second inner face section.

Description

Cutting inserts, tool bodies and cutting tools

The present invention relates to a cutting insert that is detachably attached to a tool body of a cutting tool, and a tool body and a cutting tool on which the cutting insert is attached.

There are various types of cutting tools that attach cutting inserts to a tool body using tightening screws. Generally, for a cutting tool in which a cutting insert is mounted on a tool body using a tightening screw, the center axis of the screw hole on the bottom surface of the insert seat corresponding to the tightening screw is set to the center axis of the hole of the cutting insert. A method is known in which the insert seat is formed so as to be shifted to a predetermined side wall surface side. In this way, when the center axis of the screw hole is formed so as to be shifted from the center axis of the hole of the cutting insert, the cutting insert can be pressed against the predetermined side wall surface side of the insert seat and mounted.

Furthermore, Patent Document 1 is in a state where the lower surface of the cutting insert is in contact with the bottom surface of the insert seat, is inclined at a predetermined angle with respect to a line orthogonal to the bottom surface, and the screw is passed through the hole of the cutting insert, It is disclosed to screw into a screw hole on the bottom surface. Thereby, the cutting insert can be pressed and fixed to a specific side wall surface extending so as to intersect the bottom surface. In addition, in the cutting insert of patent document 1, the recessed part dented in the direction away from the center axis line of the hole is provided in the cylindrical inner surface of the hole of the cutting insert. With this recess, the cutting insert of Patent Document 1 prevents the screw portion of the screw from interfering with the hole of the cutting insert when the screw is inclined and screwed into the screw hole.

Special table 2008-520447 gazette

In the conventional method in which the center axis of the screw hole is shifted from the center axis of the hole of the cutting insert, the tightening state of the cutting insert may not be stable. That is, the cutting insert may be mounted in various postures with respect to the side wall surface of the insert seat. In other words, when the cutting insert is mounted, various gaps may be generated between the insert seat and the cutting insert. When the clearance is generated, the cutting insert is easily displaced during the cutting process. As a result, the cutting insert may be easily damaged or the processing accuracy of the workpiece may be reduced.

In addition, even with the conventional method of inclining a screw with respect to the bottom surface of the insert seat, the cutting insert may be mounted in various postures with respect to the side wall surface of the insert seat. ,There is a limit.

The present invention aims to improve the stability of the cutting insert in the insert seat.

According to one aspect of the invention,
Two end surfaces comprising a first end surface and a second end surface facing the first end surface;
A peripheral side surface connecting the two end surfaces;
At least one cutting edge formed at a crossing ridge line portion between the first end surface and the peripheral side surface;
A hole penetrating the two end faces;
The hole has a first hole portion and a second hole portion, and the second hole portion has an associated cutting edge formed in a direction of a center axis of the hole rather than the first hole portion. It is located on the first end face side and opens toward the first end face, and the second hole has a larger inner dimension than the first hole,
The second hole portion has a first inner surface portion and a second inner surface portion in the circumferential direction of the hole,
The first inner surface portion is closer to the central axis than the second inner surface portion.
A cutting insert is provided.

Preferably, in a plane defined to be orthogonal to the central axis with respect to the second hole portion of the hole, the second inner surface portion has a shape along a basic circle centered on the central axis, One inner surface portion extends from the basic circle toward the central axis.

The hole in the first end surface of the hole may have a non-circular shape when viewed from the direction facing the first end surface. The first hole may have a convex portion toward the central axis and toward the first end surface.

Preferably, when the cutting insert is viewed from the side facing the first end surface, the first inner surface portion is located at a position deviated from between the central axis of the hole and the corresponding cutting edge.

Preferably, in a cross section determined to include the center axis of the hole, an angle formed between a tangent line in the first inner surface portion and the center axis of the hole is a first angle θ1, and the angle in the first hole portion is When the angle formed between the tangent line and the center axis of the hole is the second angle θ2, θ1 <θ2.

Preferably, when the cutting insert is viewed from the side facing the first end surface, a region associated with the first inner surface portion is located in a region outside the space between the central axis and the first inner surface portion of the hole. One hole portion extends.

A rake face may be formed on the first end face or the peripheral side face. When the first end surface has three corner portions when the cutting insert is viewed from the side facing the first end surface, the hole is formed around the central axis in a three-fold rotational symmetry. It is good to be.

The present invention also exists in a tool body having at least one insert seat. The insert seat may be configured such that the cutting insert is detachably mounted.

A further aspect of the invention is:
A cutting tool comprising a tool body comprising at least one insert seat and at least one cutting insert detachably attached to the insert seat,
The cutting insert is the cutting insert,
The insert seat includes a bottom surface with which the second end surface can contact, and at least one side wall surface extending so as to intersect the bottom surface,
When the cutting insert is attached to the insert seat using a screw member, the first inner surface portion related to the working cutting edge is located in a first direction with respect to the central axis of the hole, and The second direction in which the central axis of the screw hole is displaced from the central axis of the hole of the cutting insert is in a non-parallel relationship with the first direction.
Provide cutting tools.

Preferably, the first direction extends in a direction intersecting the first side wall surface, and the second direction is a second side wall surface side extending so as to intersect the first side wall surface with respect to the first direction. It is shifted to.

The screw member has a screw part that can be screwed into the screw hole and a head part thicker than the screw part, and the head part of the screw member is when the cutting insert is attached to the insert seat. The first hole may be reached while contacting the first inner surface of the second hole. Preferably, when the cutting insert is attached to the insert seat, the head portion of the screw member is located on the central axis side and the first end face side of the first hole portion in the hole of the cutting insert. Reach up to the convex part.

FIG. 1 is a partially enlarged perspective view in the vicinity of a cutting insert of a cutting tool according to an embodiment of the present invention. FIG. 2 is a perspective view of the cutting tool of FIG. 3 is a partially enlarged perspective view around one insert seat in the cutting tool of FIG. 1 with the cutting insert and the clamp member removed. FIG. 4 is a perspective view of a cutting insert in the cutting tool of FIG. FIG. 5 is a plan view of the cutting insert of FIG. FIG. 6 is a front view of the cutting insert of FIG. FIG. 7 is a right side view of the cutting insert of FIG. 8 is a cross-sectional view of the cutting insert of FIG. 4 taken along the line VIII-VIII in FIG. 9 is a cross-sectional view of the hole of the cutting insert of FIG. 4 taken along the line IX-IX in FIG. FIG. 10 is a view showing a screw member as a clamp member used in the cutting tool of FIG. FIG. 11 is a partially enlarged view of the vicinity of one cutting insert in the cutting tool of FIG. FIG. 12 is a schematic cross-sectional view of the cutting tool of FIG. 1 taken along the line XII-XII of FIG. FIG. 13 is a schematic diagram for explaining the pressing direction of the cutting insert against the two side wall surfaces of the insert seat.

Embodiments according to the present invention will be described with reference to the drawings. FIG. 1 is a partially enlarged perspective view in the vicinity of a cutting insert of a cutting tool according to an embodiment of the present invention. FIG. 2 is a perspective view of the cutting tool of FIG. FIG. 3 is a partially enlarged perspective view of the periphery of the insert seat from which the cutting insert and the clamp member are removed from the cutting tool of FIG. FIG. 4 is a perspective view of a cutting insert in the cutting tool of FIG. FIG. 5 is a plan view of the cutting insert of FIG. FIG. 6 is a front view of the cutting insert of FIG. FIG. 7 is a right side view of the cutting insert of FIG. 8 is a cross-sectional view of the cutting insert of FIG. 4 taken along the line VIII-VIII in FIG. 9 is a cross-sectional view of the hole of the cutting insert of FIG. 4 taken along the line IX-IX in FIG. FIG. 10 is a view showing a screw member as a clamp member used in the cutting tool of FIG. FIG. 11 is a partially enlarged view of the cutting tool in FIG. 1 near one cutting insert fixed to the tool body. 12 is a schematic cross-sectional view of the cutting tool of FIG. 1 taken along the line XII-XII of FIG. 11, and is a view in a state where the screw member is loosely tightened (a state in the middle of tightening). FIG. 13 is a schematic diagram for explaining the pressing direction of the cutting insert against the two side wall surfaces of the insert seat.

As shown in FIGS. 1 and 2, the cutting tool 20 of this embodiment is a rotary cutting tool that detachably attaches the cutting insert 1 to the tool body 21. The tool body 21 has an axis line 21 a extending from the distal end side to the proximal end side, and this axis line 21 a can be a rotation axis line of the cutting tool 20. The cutting tool 20 can be used for cutting by being rotated relative to the work material. The cutting tool 20 itself may rotate relative to the work material, or the work material may rotate relative to the cutting tool without rotating the cutting tool 20. The cutting tool 20 uses a plurality of cutting inserts 1, a tool body 21, and a plurality of clamp members 30.

4 to 7, each cutting insert 1 has a substantially triangular plate shape. Each cutting insert 1 includes a first end surface 2, a second end surface 3, and a peripheral side surface 4. Here, the first end face 2 is referred to as the upper face 2. Similarly, the second end surface 3 is referred to as a lower surface 3. Note that terms such as the upper surface 2 and the lower surface 3 are used to indicate the orientation in the space, but this is for convenience and is not intended to define the absolute orientation or positional relationship in the space. Absent. Unless otherwise noted, the terms used in this description for the orientation and positional relationship in the space are the same. Each cutting insert 1 has a hole 5 corresponding to each clamp member 30. The hole 5 penetrates between the upper surface 2 and the lower surface 3.

The tool body 21 has a plurality of chip seats, that is, insert seats 22 for mounting the plurality of cutting inserts 1 respectively. More specifically, since three cutting inserts 1 are used in the cutting tool 20 of this embodiment, the tool body 21 includes three insert seats 22. And in the cutting tool 20, all the some cutting insert 1 is made into the same shape. That is, the cutting tool 20 has the number of blades corresponding to the number of cutting inserts 1 used, and specifically has three blades. Therefore, for simplification of description, the following description will be made with respect to one cutting insert 1, but the same applies to all other cutting inserts 1. Also, the plurality of clamp members 30 and the plurality of insert seats 22 have the same shape as the cutting insert. Hereinafter, one clamp member 30 and one insert seat 22 will be described, but the same applies to all other clamp members 30 and insert seats 22.

In the cutting insert 1 of this embodiment, a rake face is formed on the upper surface 2. A cutting edge 2g is formed at the intersecting ridge line portion between the rake face of the upper surface 2 and the flank face of the peripheral side surface 4. The cutting insert 1 has a plurality of (here, three) cutting edges 2g over the entire circumference of the intersecting ridge line portion between the upper surface 2 and the peripheral side surface 4, but at least one of the cutting ridge lines only at least a part of the intersecting ridge line portion. A cutting edge may be formed. The upper surface 2 has a substantially triangular shape in plan view and has three corner portions 2c. Since one cutting edge 2g is associated with each corner portion 2c, the cutting insert 1 has three cutting edges 2g. Each cutting edge 2g has a corner cutting edge 2h along the corner portion 2c, a first cutting edge 2i extending from the corner cutting edge 2h, and the corner cutting edge 2h facing the side opposite to the first cutting edge 2i. And a second cutting edge 2j extending. The three cutting edges 2g are arranged symmetrically with respect to the central axis A of the through hole 5 by 120 °. Corresponding to this, the cutting insert 1 is formed to be 120 ° rotationally symmetric (three-fold rotational symmetry) with respect to the central axis A of the through hole 5. In the cutting insert 1, the three cutting edges 2g are continuous with each other, but may be independent from each other.

6 and 7, the first cutting edge 2i is inclined so as to gradually approach the lower surface 3 side in the direction of the central axis A as it is away from the corner cutting edge 2h of the same cutting edge 2g. Similarly, in FIG. 6 and FIG. 7, the second cutting edge 2j is inclined so as to gradually approach the lower surface 3 side in the direction of the central axis A as it is away from the corner cutting edge 2h of the same cutting edge 2g. Therefore, in each cutting edge 2, the corner cutting edge 2 h is located farthest from the lower surface 3 in the direction of the central axis A.

In the cutting insert 1 attached to the tool body 21, a part of the upper surface 2 is configured to function as a rake face of one working cutting edge 2g ', and a part of the peripheral side surface 4 is the same working cutting edge 2g. It is comprised so that it may function as '' flank. Various changes can be made in the cutting insert 1. For example, the cutting edge may be entirely or partially inclined, and the cutting edge portion may be linear or curved.

4 to 7, the cutting insert 1 is a so-called positive type cutting insert 1 in which a cutting edge and a rake face are formed on the upper surface 2 side. In other words, in the cutting insert 1 of this embodiment, the end surface on the side where the rake face is formed is referred to as the upper surface 2 or the first end surface 2. That is, when the cutting insert 1 of this embodiment determines the virtual surface IS parallel to the central axis A of the hole 5 so as to pass through the cutting edge 2g, the peripheral side surface 4 is separated from the cutting edge with respect to the virtual surface IS. It forms so that it may incline to the center axis line A side as it leaves | separates (in FIG. 6, 0 degrees <angle (alpha) <90 degrees). The present invention can also be applied to a cutting insert in which a rake face is formed on the peripheral side surface 4 instead of the upper surface 2. A cutting insert in which a rake face is formed on the peripheral side surface 4 may be referred to as a vertical insert type.

The peripheral side surface 4 is provided with respect to the first side surface portion 4a extending along the first cutting edge 2i, the second side surface portion 4b extending along the second cutting edge 2j, and the corner cutting edge 2h. And a corner side surface portion 4c extending so as to connect the first and second

side surface portions

4a and 4b. As described above, since the cutting insert 1 has the three cutting edges 2g, the number of each of the first side surface portion 4a, the second side surface portion 4b, and the corner side surface portion 4c is three.

3, each insert seat 22 has a bottom surface 23 and a side wall surface 24. The contour shape of the bottom surface 23 of the insert seat 22 corresponds to the contour shape of the lower surface 3 of the cutting insert 1. In this embodiment, since the lower surface 3 of the cutting insert 1 has a substantially triangular shape so as to correspond to the shape of the upper surface 2, the contour shape of the bottom surface 23 is a substantially triangular shape. Further, in order to fix the cutting insert 1 to the insert seat 22, a screw member 30 a is used as the clamp member 30. The screw member 30a is also called a fastening screw 30a. A screw hole 25 corresponding to the fastening screw 30a intersects the bottom surface 23 of the insert seat 22. That is, the screw hole 25 is opened in the bottom surface 23. The fastening screw 30 a can be screwed into the screw hole 25. By moving the screw 30 a forward and backward along the central axis B of the screw hole 25, the cutting insert 1 can be fastened to or removed from the insert seat 22. When the tightening screw 30 a is tightened, the cutting insert 1 is pressed against the bottom surface 23 and the side wall surface 24 of the insert seat 22 and is mounted on the insert seat 22 of the cutting tool 20. When the fastening screw 30 a is loosened and removed, the cutting insert 1 can be removed from the insert seat 22. Since the cutting insert 1 of this embodiment has three sets of cutting edges 2g, the cutting insert 1 can be used three times for one cutting insert 1 by rotating the cutting insert 1 120 [deg.] And reattaching it to the cutting tool 20. It is. However, the outline shape of the cutting insert 1 is not limited to the shape of this embodiment. For example, the present invention can be applied to a substantially rectangular plate-shaped cutting insert or a substantially octagonal plate-shaped cutting insert. The present invention can be applied to any outline-shaped cutting insert as long as it has a hole 5 penetrating the upper surface and the lower surface and the upper surface is substantially polygonal in a plan view. In FIG. 3, an internal thread (thread) is formed on the inner surface of the screw hole 25.

The insert seat 22 of the tool body 21 of this embodiment has two side wall surfaces 24 for fixing the cutting insert 1. Each of the two side wall surfaces 24 extends so as to intersect the bottom surface 23 in which the screw hole 25 is formed. One of the two side wall surfaces is a first side wall surface 24a serving as a main restraint surface. The other is a second side wall surface 24b that serves as a secondary restraint surface. The main constraining surface is a wall surface acting mainly among a plurality of wall surfaces in contact with the cutting insert 1. Acting proactively means being most strongly involved in the restraint of the cutting insert 1 (among the primary and secondary restraint surfaces). Therefore, it is preferable that the main restraint surface is formed larger than the sub restraint surface. In other words, among the plurality of side wall surfaces in contact with the cutting insert 1, the side wall surface having the largest area in contact with the cutting insert 1 may be referred to as a main constraining surface. The sub-constraint surface is a side wall surface other than the main constraining surface among the plurality of side wall surfaces in contact with the cutting insert 1. In this embodiment, since the contour shape of the cutting insert 1 is substantially triangular when viewed from the upper surface 2 side, the first side wall surface 24a is disposed on the base end side of the tool body, and the second side wall surface 24b is It is arranged on the tip side of the tool body. The first side wall surface 24a is wider than the second side wall surface 24b, and acts mainly when the cutting insert 1 is fixed. The second side wall surface 24 b assists the first side wall surface 24 a to fix the cutting insert 1. That is, the first side wall surface 24a is a main restraint surface, and the second side wall surface 24b is a sub restraint surface. The cutting insert 1 abuts on the first side wall surface 24a, which is the main constraining surface, so that the rotational direction around the central axis is constrained first, and then comes into contact with the first side wall surface 24a. It is preferable that the fixed position is determined by abutting on the second side wall surface 24b which is a restraining surface. When the cutting insert 1 is thus mounted on the tool body 21 of the cutting tool 20, the orientation and fixing position of the cutting insert 1 are stabilized. When the orientation and the fixed position of the cutting insert 1 are stabilized, the machined surface quality of the machined surface of the work material is improved. Or it suppresses that the cutting insert 1 shifts | deviates during cutting, and abnormal damages, such as a chip | tip of a cutting blade, are prevented. In the tool body 21 of this embodiment, the first side wall surface 24a is divided by a recess and consists of two surface portions. If the 1st side wall surface 24a is parted in such a shape, the cutting insert 1 will contact reliably the both ends vicinity of the 1st side wall surface 24a, and the fixability of the cutting insert 1 will further improve. Conversely, if the cutting insert 1 comes into contact near the center of the first side wall surface 24a, there is a gap between the cutting insert and the first side wall surface 24a near both ends of the first side wall surface 24a. , Cutting insert fixing becomes unstable. Therefore, like the insert seat 22 of this embodiment, a recess is positively formed near the center of the first side wall surface 24a to form a gap, and the cutting insert is securely inserted near both ends of the first side wall surface 24a. It is preferable to make it contact, ie contact. However, it is not limited to this. The first side wall surface 24a may be a single plane that is not divided by the recess. Moreover, it is not limited to a plane, The 1st side wall surface 24a may be made into a curved surface.

The center axis B of the screw hole 25 formed in the bottom surface 23 of the insert seat 22 is such that the hole 5 of the cutting insert 1 is placed when the cutting insert is placed on the insert seat 22 in a state of being firmly in contact with the two side wall surfaces. It is formed so as to deviate from the central axis A. The positional relationship between these axes A and B is conceptually shown in FIG. 13, but in reality, they are not displaced as much as shown in FIG. This deviation amount may be referred to as a centering amount. In this embodiment, the centering amount of the central axis B of the screw hole 25 is about 0.2 mm. However, it is not limited to this. The centering amount may be about 0.1 mm. Conversely, the centering amount may be about 0.3 mm. When the insert seat 22 is viewed from the direction facing the bottom surface 23 of the insert seat 22, the direction in which the center axis B of the screw hole 25 is shifted from the center axis A of the hole 5 is the centering direction (arrow a <b> 2 in FIGS. 11 and 13). See). The centering direction is basically a direction toward the main restraint surface 24a, and is preferably a direction toward both side wall surfaces 24 of the main restraint surface 24a and the sub restraint surface 24b. In this embodiment, when the insert seat 22 is viewed from the direction facing the bottom surface 23 of the insert seat 22 (that is, the cutting insert from the side facing the top surface 2 of the cutting insert 1 placed on the insert seat 22). ), The centering direction is determined so that the first side wall surface 24a (extension surface thereof) and the second side wall surface 24b (extension surface thereof) generally face each other. That is, from such a viewpoint, the screw hole 25 and the through hole 5 of the cutting insert 1 are respectively designed.

Now, in order to make the cutting insert 1 firmly contact with the side wall surface 24 (24a, 24b) of the insert seat 22, the cutting tool 20 adopts a further configuration in addition to the above-described configuration of the centering. This configuration is mainly applied to the hole 5 of the cutting insert 1. Specifically, the hole 5 of the cutting insert 1 includes a fixing portion 8 that comes into contact with the clamp member 30 and firmly attaches the cutting insert 1 to the tool body 21 of the cutting tool 20 by the above-mentioned centering, In the direction of the central axis A of the hole 5, a guide surface portion 9 is provided that is located on the upper surface 2 side of the fixed portion 8.

Here, the screw member 30a as the clamp member 30 will be described with reference to FIG. The screw member 30a includes a screw portion 30b having a thread and a head portion 30c provided at one end of the screw portion 30b. The screw portion 30b and the head portion 30c are coaxial with each other in the direction of the axis C of the screw 30a. Has been placed. The screw portion 30b is configured as a male screw so as to be able to be screwed into the screw hole 25 of the insert seat 22. The head portion 30c is thicker than the screw portion 30b. As shown in FIG. 1, the head portion 30 c has an engagement portion 30 d with which a fastener can engage with an end portion in the axis C direction of the screw. As shown in FIG. 10, the head portion 30 c faces the connecting portion with the screw portion 30 b, and the outer peripheral surface thereof has a cylindrical portion 30 e, a peripheral convex portion 30 f connected to the cylindrical portion 30 e, an inclined surface portion 30 g connected to the peripheral convex portion 30 f, It has the circumferential recessed part 30h connected to each of the inclined surface part 30g and the thread part 30b. The cylindrical portion 30e is configured so that the diameter around the axis C does not substantially change. The inclined surface portion 30g has a substantially truncated conical shape, and is configured such that its diameter tapers from the head portion 30c side toward the screw portion 30b side. The circumferential convex portion 30f smoothly connects the cylindrical portion 30e and the inclined surface portion 30g.

Now, the description returns to the hole 5 of the cutting insert 1. The fixing portion 8 of the hole 5 is configured so that the head portion 30c of the screw 30a cannot pass through. The guide surface portion 9 of the hole 5 is configured so that the head portion 30c of the screw 30a can pass with a margin. The fixing portion 8 is a portion that comes into contact with the head 30c of the tightening screw 30a when the cutting insert 1 is finally fixed to the tool body 21 of the cutting tool 20. The hole 5 is configured such that the hole diameter or the inner dimension is gradually enlarged from the fixing portion 8 toward the upper surface 2 side including the portion of the fixing portion 8. That is, a part of the inclined surface 6 where the hole diameter is gradually enlarged serves as the fixing portion 8. When the cutting insert 1 is attached to the insert seat 22, the fixing portion 8 is arranged so that the head 30 c of the tightening screw 30 a is centered in the hole 5 as if the fixing portion 8 is generally in contact with the head 30 c by point contact or line contact. To be received in the direction of the axis A, the head 30c is contacted. Here, the surface portion including the fixing portion 8 is referred to as a fixing surface portion 10. The fixed surface portion 10 is a curved surface portion that curves in a convex shape. Therefore, when the cutting insert 1 is fixed to the insert seat 22, at least a part of the inclined surface portion 30 g and the circumferential convex portion 30 f of the screw head 30 c, preferably the inclined surface portion 30 g, is applied to the fixed surface portion 10 including the fixing portion 8. You can touch. This abutment can bring about a fixing effect due to the centering.

The hole 5 includes a guide surface portion 9 on a side closer to the upper surface 2 than the fixed portion 8. When the cutting insert 1 is mounted on the tool body 21 of the cutting tool 20, the guide surface portion 9 can contact the screw 30 a before the fixing portion 8. The guide surface portion 9 is formed as an inclined surface so as to be away from the central axis of the hole 5 as it approaches the upper surface 2. When the head portion 30c of the screw 30a presses the guide surface portion 9, the side surface portion (along the predetermined side portion 12 between the adjacent corner portions of the upper surface 2) of the cutting insert 1 is changed to the insert seat 22 of the cutting tool 20. It is pushed toward a predetermined side wall surface 24 and comes into contact therewith. As described above, the predetermined side wall surface 24 is preferably the first side wall surface 24a serving as the main constraining surface. That is, when the cutting insert 1 is mounted, the side surface portion along the predetermined side portion 12 of the cutting insert 1 comes into contact with the first side wall surface 24a by the action of the guide surface portion 9, and the cutting insert 1 is restrained. . Thereby, the cutting insert 1 can be mounted on the insert seat 22 of the tool body 21 of the cutting tool 20 in a stable orientation and a fixed position each time. Here, the predetermined side 12 of the cutting insert 1 is referred to as a first side. As described above, the cutting insert 1 can be used three times by rotating 120 ° and remounting the cutting insert 1. Therefore, the first side portion 12 is a term used for convenience, and substantially three sides of the substantially triangular shape of the upper surface 2 have the same shape and function and can be the first side portion. . In particular, here, the first side portion 12 is a portion along the edge of the first side surface portion 4a, but may extend over the first and second

side surface portions

4a and 4b adjacent to each other.

Thus, the hole 5 includes the fixed portion 8 and the guide surface portion 9. The hole 5 includes a first hole 5a in which the fixing portion 8 is formed, a second hole 5b located on the upper surface 2 side of the first hole 5a in the direction of the center axis A of the hole 5, and a center axis of the hole 5 A third hole portion 5c located on the lower surface 3 side of the first hole portion 5a in the A direction. The first hole 5a has a smaller inner diameter or inner dimension than the second hole 5b. The first hole 5a has a larger inner diameter or inner dimension than the third hole 5c, but may have substantially the same inner dimension as the third hole 5c. In the cutting insert 1, the fourth hole portion 5 d is provided on the lower surface 3 side of the third hole portion 5 c in the direction of the central axis A of the hole 5. The fourth hole portion 5d has an inner dimension larger than that of the third hole portion 5c. The 4th hole 5d is provided as a diameter expansion part in order to avoid interference of the screw 30a with respect to the cutting insert. The 4th hole 5d is good to be designed based on the function as a seating surface of the lower surface 3 when the cutting insert 1 is attached to the insert seat 22.

The first hole portion 5a is a portion where the fixing portion 8 is formed, as can be understood from the above description. In the cutting insert 1, the first hole 5 a is inclined with respect to the central axis A so that the hole diameter or the inner dimension gradually increases toward the upper surface 2 generally over the entire circumference of the hole 5. Yes. The first hole 5a is generally convex toward the central axis A side and the upper surface 2 side.

The second hole portion 5b is a portion where the guide surface portion 9 is formed, as can be understood from the above description. The second hole portion 5 b has a first inner surface portion 5 e and a second inner surface portion 5 f in the circumferential direction of the hole 5. The first inner surface portion 5 e corresponds to the guide surface portion 9. Here, the cross-sectional view of FIG. 9 taken along the line IX-IX of FIG. 8 orthogonal to the central axis A at the position of the second hole 5b is referred to. The cross-sectional view of FIG. 9 shows the shape of the hole 5 along a plane defined to be orthogonal to the central axis A with respect to the second hole portion 5 b of the through hole 5. In FIG. 9, the first inner surface portion 5e is a substantially linear portion, and the second inner surface portion 5f is an arc-shaped portion. The second inner surface portion 5 f has a shape along a basic circle BC centered on the central axis A of the hole 5. In FIG. 9, the first inner surface portion 5 e is inside the basic circle BC and protrudes from the basic circle BC toward the center axis A side of the hole 5. Therefore, the first inner surface portion 5e is closer to the central axis A than the second inner surface portion 5f (L1 <L2 in FIG. 9).

Three first inner surface portions 5 e are formed in the hole 5. The number of first inner surface portions 5e matches the number of cutting edges 2g. That is, when the cutting insert 1 is attached to the insert seat 22 so that one cutting edge 2g becomes the working cutting edge 2g ', one of the three first inner surface portions 5e acts effectively. Specifically, when the lower right cutting edge 2g in FIG. 5 is the working cutting edge 2g ′, the first inner surface portion 5e, that is, the guide surface portion 9 at a position substantially sandwiching the working cutting edge 2g ′ and the central axis A is provided. It can work as the action guide surface portion 9 '. The through-hole 5 has a shape that is rotationally symmetrical three times around the central axis A in FIGS. Thus, the cutting insert according to the present invention has the number n of the cutting edges 2g (where n is a natural number of 1 or more) and the rotational symmetry (n-fold rotational symmetry) around the central axis A of the through hole 5. Can be related.

When attaching the cutting insert 1 to the insert seat 22, it is preferable that the direction of the action guide surface portion 9 ′ from the center axis A of the hole 5 is a direction (non-parallel direction) different from the centering direction. The centering direction is related to the fixed portion 8. The centering direction is determined in a direction in which the force pressing the cutting insert 1 is properly distributed not only to the first side wall surface 24a serving as the main constraining surface but also to the second side wall surface 24b serving as the sub constraining surface. The fixing portion 8 is formed so as to realize this centering direction. That is, the fixing portion 8 is arranged and formed so that the fixing force in the centering direction can be exerted on the cutting insert 1. On the other hand, the guide surface portion 9 is formed in the radial direction centering on the central axis A of the hole 5 in a direction in which a force that strongly presses the cutting insert 1 mainly against only the first side wall surface 24a is applied. More specifically, the guide surface portion 9 passes through the central axis A of the hole 5 and is formed in a direction intersecting the first side portion 12 of the cutting insert 1 corresponding to the first side wall surface 24a. In the cutting insert 1, as can be understood from FIGS. 5 and 11, a straight line LA (corresponding to the line segment L <b> 1 in FIG. 9) connecting the portion closest to the central axis A of the guide surface portion 9 and the central axis A is the first. Intersects with the side 12. And when the cutting insert 1 is mounted in the insert seat 22, this straight line LA cross | intersects the 1st side wall surface 24a in FIG. The VIII-VIII cross-sectional line in FIG. 5 corresponds to the XII-XII cross-sectional line in FIG. FIG. 11 is a view as seen from the side facing the upper surface 2 of the fixed cutting insert 1. In FIG. 11, the central axis A of the hole 5 can be represented by a point.

Here, a cross-sectional schematic diagram (FIG. 12) of the cutting tool 20 at a position along the XII-XII cross-sectional line of FIG. FIG. 12 is a view in the middle of attachment of the cutting insert 1. In FIG. 12, the first side surface portion 4a of the peripheral side surface 4 of the cutting insert 1 is in contact with the first side wall surface 24a, and the head portion 30c of the screw member 30a starts to contact the action guide surface portion 9 ′. However, it is shown. It will be understood by those skilled in the art that FIG. 12 exaggerates the arrangement and configuration of the screw member 30a, the cutting insert 1 and the screw hole 25.

When the screw member 30a is started to be screwed in a state where the cutting insert 1 is placed on the insert seat 22, as shown in FIG. 12, the head portion 30c of the screw member has an action guide surface portion 9 corresponding to the action cutting edge 2g ′. It starts to contact ´. As shown in FIG. 13, the action guide surface portion 9 ′ corresponding to the action cutting edge 2g ′ is at a position deviated from between the action cutting edge 2g ′ and the center axis A, and particularly here, the center axis A Is generally on the opposite side of the working cutting edge 2g ′. Then, the screw member 30a omitted in FIG. 13 is further screwed into the screw hole 25, and the head 30c moves while being in contact with the action guide surface portion 9 ′, so that the screw member 30a is elastically deformed. The insert 1 is further pressed toward the first side wall surface 24a. Then, the screw member 30 a is further screwed in, and the head portion 30 c starts to contact the fixed portion 8. The cutting insert 1 is pressed in the centering direction a2 in the insert seat 22 by the contact of the screw 30a with the fixing portion 8. As shown in FIGS. 11 and 13, the pressing direction of the cutting insert 1 against the side wall surface 24 is changed from the direction a <b> 1 facing only the first side wall surface 24 a to the first side wall surface 24 a and the second side wall surface. As shown by the arrow a3, the direction is changed to the direction a2 in both directions with respect to 24b. That is, the cutting insert 1 is in the centering direction (second direction) a2 with the first direction a1 directed to the first side wall surface 24a as a reference from the state where it is pressed only on the first side wall surface 24a. While being pressed against the first side wall surface 24a, it is gradually pressed. Therefore, by firmly screwing the screw 30a into the screw hole 25, the cutting insert 1 can abut against the second side wall surface 24b while abutting against the first side wall surface 24a. It can be firmly fixed to the insert seat 22. In the schematic diagram of FIG. 13, the axis A of the cutting insert and the axis B of the screw hole are exaggerated to show the centering direction.

In the cutting insert 1, the fixing portion 8 is formed over the entire circumference of the hole 5. However, the direction in which the fixing portion 8 is formed is limited to such an extent that the cutting insert 1 can be pressed in the centering direction a2. The formation region can be narrowed. The direction in which the fixing portion 8 is formed can be determined in a direction in which the center axis B of the screw hole 25 of the insert seat 22 is shifted from the center axis A of the hole 5. That is, in this case, the direction in which the fixing portion 8 is formed is the centering direction. For example, in the case shown in FIG. 13, the fixing portion 8 can be limited to the region 8z so as to push the cutting insert 1 in the centering direction a2 with respect to the working cutting edge 2g ′. As already described with respect to the cutting insert 1, the guide surface portion 9 is preferably formed in a direction different from the direction of centering. The guide surface portion 9 is formed so as to come into contact with the clamp member 30 before the fixed portion 8. That is, the guide surface portion 9 is preferably formed on the inner surface of the hole 5 at the protruding portion 11 that protrudes inward from the basic circle BC. Protruding inward of the hole 5 projects inward from the basic circular shape of the hole 5 in the shape of the cut surface that cuts the hole 5 parallel to the upper surface 2 as described above (see FIG. 9). Refers to that. In order to form such a protrusion 11, the opening on the upper surface 2 side of the hole 5 is preferably not circular. That is, the opening on the upper surface 2 side of the hole 5 is formed in a graphic shape in which the distance from the central axis A of the hole 5 is not constant so that the portion corresponding to the protrusion 11 is close to the central axis A of the hole 5. It is preferable.

Further, the distance between the lower surface 3 side end of the guide surface portion 9 formed in the protruding portion 11 and the center axis A of the hole 5, and the distance between the upper surface 2 side end of the fixing portion 8 and the center axis A of the hole 5, The difference is preferably in the range of 0.01 mm or more and 1.00 mm or less. In the hole 5 of the cutting insert 1, a concave transition portion 5e is formed between the first surface portion 5a and the second surface portion 5b for smoothly connecting them. The difference in distance to the central axis A between the upper surface 2 side end portion and the lower surface 3 side end portion of the transition portion corresponds to the difference in distance between the guide surface portion 9 and the fixed portion 8 with respect to the central axis A. When the distance between the guide surface portion 9 and the fixed portion 8 and the central axis A is within such a difference range, first, the direction of the cutting insert 1 is constrained by the contact between the screw 30a and the guide surface portion 9, and thereafter The effect of determining the fixing position of the cutting insert 1 by the contact between the screw 30a and the fixing portion 8 is high.

Here, the portion of the guide surface portion 9 that substantially contacts the clamp member 30 first is called the contact start portion 7 in particular. The contact start portion 7 is a portion that starts to contact the clamp member 30 generally by point contact or line contact. Consider the shape of the cut surface of the hole 5 of the cutting insert 1 cut along a plane that includes the center axis A of the hole and intersects the guide surface 9 at a right angle in a cross section orthogonal to the center axis A. That is, consider a sectional view taken along the line VIII-VIII in FIG. 5 as shown in FIG. In addition, in order to make explanation easy to understand, the case of the cutting insert 1 in which both the contact start portion 7 and the fixing portion 8 appear in the cut surface view will be described. As already described, in practice, the fixing portion 8 may be formed partially or entirely at a position shifted from this cross section. Rather, it is preferable that the fixing portion 8 is formed at a shifted position so as not to appear in the cut surface view. Therefore, FIG. 8 is also a diagram for conceptually explaining the fixing portion 8 and the contact start portion 7 in an easy-to-understand manner. As shown in FIG. 8, the angle formed between the tangent line at the contact start portion 7 and the central axis A of the hole 5 is defined as a first angle θ1. The angle formed between the tangent line at the fixing portion 8 and the central axis A of the hole 5 is defined as a second angle θ2. At this time, it is preferable that θ1 <θ2. That is, it is preferable that the inclination angle θ2 of the fixed portion 8 is larger than the inclination angle θ1 of the contact start portion 7. In the case where the fixing portion 8 does not appear in the sectional view taken along the line VIII-VIII, the corresponding angle in the sectional view including the fixing portion 8 may be the second angle θ2. By making the angle θ2 larger than the angle θ1, when the cutting insert 1 is mounted on the cutting tool 20, the clamp member 30 first contacts the contact start point 7 and finally contacts the fixing portion 8. Fixed. That is, the contact start point 7 can be provided in the cross section of the section view along the VIII-VIII cross section line, not in the other cross section. In other words, by making the angle θ2 larger than the angle θ1, the contact start point 7 can be brought close to the fixed portion 8 in the plan view of FIG.

The hole 5 of the cutting insert 1 of this embodiment has an irregular shape that is not substantially circular up to the lower surface 3 side in plan view. However, it is not limited to this. On the lower surface 3 side away from the upper surface 2, the hole 5 may have, for example, at least one of the first hole portion and the third hole portion having a substantially circular cross section. The hole 5 may have any shape as long as it has the fixing portion 8 and the guide surface portion 9 and does not interfere with the screw portion of the fastening screw 30a. The hole 5 is preferably substantially circular in the vicinity of the lower surface 3. If the hole 5 is substantially circular, the mold for manufacturing the cutting insert 1 can also be substantially circular, and therefore it is easy to manufacture and the manufacturing cost can be suppressed.

As described above, the cutting tool 20 of the present embodiment uses the tightening screw 30 a as the clamp member 30. The fastening screw 30a has a head portion and a screw portion. The head has a recess corresponding to the wrench. In this embodiment, the wrench and recess are in the shape of a Torx. However, it is not limited to this. For example, the recess may be a hexagon or the like, and may correspond to a hexagon wrench. Furthermore, it is preferable that the head of the fastening screw 30a has two contact portions. One is a contact portion corresponding to the fixed portion 8 of the cutting insert 1. The other is a contact portion corresponding to the guide surface portion 9 of the cutting insert 1. The contact portion corresponding to the fixing portion 8 is formed on the screw side of the head, that is, the lower surface (for example, the inclined surface portion 30g) in FIG. The contact portion corresponding to the guide surface portion 9 is formed on the peripheral surface side of the head as compared with the contact portion corresponding to the fixed portion 8 (for example, the circumferential convex portion 30f). However, it is not limited to this. Moreover, the shape of the clamp member 30 is not limited to the shape of this embodiment. Various known prior art clamping members can be applied as the clamping member 30.

The present invention is particularly effective when the side wall surface 24 of the insert seat 22 has two surface portions, a main restraint surface and a sub restraint surface. That is, the present invention is particularly effective when the first side wall surface 24a serving as the main constraining surface is to function mainly. When the substantially triangular plate-shaped cutting insert 1 is used as in this embodiment, the insert seat 22 has two side wall surfaces 24 and the lengths of the two side wall surfaces are easily different. It will have the side wall surface 24a and the 2nd side wall surface 24b. In addition, the substantially triangular plate-shaped cutting insert 1 has an advantage that the length of the cutting edge can be increased, so that heavy cutting with a large cut can be performed. In heavy cutting with a large depth of cut, the cutting insert 1 tends to shift during cutting. Therefore, the present invention is particularly effective in the cutting tool 20 using the substantially triangular plate-shaped cutting insert 1.

The material of the cutting insert 1 is cemented carbide, cermet, ceramics and cubic boron nitride, or a material coated with a hard material surface, or a sintered body such as diamond, at least in the vicinity of the cutting edge. Made of material. In addition, it is preferable that the material of parts other than the cutting edge vicinity is also used as the same hard material.

These cutting tools can be used for cutting steel materials by being mounted on machine tools. The present invention can be applied to lathe tools, rotary cutting tools, and the like, and there are almost no restrictions on the applicable cutting tools. Although only the rotary cutting tool is described in the embodiment, the present invention is also applicable to a lathe tool.

The present invention is not limited to the embodiment described above, and various modifications and additions are possible without departing from the scope of the present invention. For example, the present invention is applicable to a cutting tool using a negative type cutting insert that can be used on both sides. The present invention includes all modifications, applications, and equivalents included in the spirit of the present invention defined by the claims.

Claims

Two end surfaces consisting of a first end surface (2) and a second end surface (3) facing the first end surface (2);
A peripheral side surface (4) connecting between the two end surfaces (2, 3);
At least one cutting edge formed at a crossing ridge line portion between the first end surface and the peripheral side surface;
A hole (5) passing through the two end faces (2, 3),
The hole (5) has a first hole part (5a) and a second hole part (5b), and the second hole part has a central axis of the hole (5) rather than the first hole part. In the direction (A), it is located on the first end surface (2) side where the associated cutting edge is formed and opens toward the first end surface (2), and the second hole portion is Has an inner dimension larger than one hole,
The second hole has a first inner surface (5e) and a second inner surface (5f) in the circumferential direction of the hole (5),
The first inner surface portion is closer to the central axis (A) than the second inner surface portion,
Cutting insert (1).
The second inner surface portion (5f) is centered on the central axis (A) in a plane defined to be orthogonal to the central axis (A) with respect to the second hole (5b) of the hole (5). The cutting according to claim 1, which has a shape along a basic circle (BC), and wherein the first inner surface portion (5e) extends from the basic circle (BC) to the central axis side (A). insert.
The opening in the first end surface (2) of the hole (5) has a non-circular shape when the hole (5) is viewed from a direction facing the first end surface (2). Cutting insert as described in.
The said 1st hole (5a) has a convex part toward the said center axis line (A) side and the said 1st end surface (2) side, It is any one of Claim 1 to 3 characterized by the above-mentioned. Cutting insert.
When the cutting insert (1) is viewed from the side facing the first end surface (2), the first inner surface portion (5e) has the cut corresponding to the central axis (A) of the hole (5). In a position outside the gap between the blades,
The cutting insert according to any one of claims 1 to 4.
In a cross section defined to include the central axis (A) of the hole (5), an angle formed between a tangent line in the first inner surface portion (5e) and the central axis (A) is defined as a first angle θ1. Cutting as described in any one of Claim 1 to 5 which is (theta) 1 <(theta) 2 when the angle which the tangent in the said 1st hole (5a) and the said central axis (A) make is 2nd angle (theta) 2. insert.
When the cutting insert (1) is viewed from the side facing the first end surface (2),
A portion (8z) of the first hole (5a) related to the first inner surface portion in a region deviated from between the central axis (A) of the hole (5) and the first inner surface portion (5e). The cutting insert according to claim 1, which extends.
The cutting insert according to any one of claims 1 to 7, wherein a rake face is formed on the first end face (2) or the peripheral side face (4).
The first end surface (2) has three corner portions (2c) when the cutting insert (1) is viewed from the side facing the first end surface,
The hole (5) is formed around the central axis (A) in a three-fold rotational symmetry,
The cutting insert according to any one of claims 1 to 8.
A tool body (21) comprising at least one insert seat (22),
The insert seat is a tool body (21) configured to be detachably mounted with the cutting insert (1) according to any one of claims 1 to 9.
A cutting tool (20) comprising a tool body (21) comprising at least one insert seat (22) and at least one cutting insert (1) detachably attached to the insert seat,
The cutting insert is a cutting insert according to any one of claims 1 to 9,
The insert seat includes a bottom surface (23) with which the second end surface (3) can abut, and at least one side wall surface (24) extending so as to intersect the bottom surface,
When the cutting insert is attached to the insert seat using a screw member (30a), the first inner surface portion (5e) associated with the working cutting edge is in relation to the central axis (A) of the hole (5). The second direction is located in the first direction (a1) and the center axis (B) of the screw hole (25) on the bottom surface is deviated from the center axis (A) of the hole (5) of the cutting insert. (A2) is in a non-parallel relationship with the first direction.
Cutting tools.
The first direction (a1) extends in a direction intersecting the first side wall surface (24a),
The second direction (a2) is shifted to the second side wall surface (24b) extending so as to intersect the first side wall surface with respect to the first direction.
The cutting tool according to claim 11.
The screw member (30a) has a screw part (30b) that can be screwed into the screw hole, and a head part (30c) that is thicker than the screw part,
The head of the screw member (30a) abuts on the first inner surface (5e) of the second hole (5b) when the cutting insert (1) is attached to the insert seat (22). While reaching the first hole (5a),
The cutting tool according to claim 11 or 12.
When the cutting insert (1) is attached to the insert seat (22), the head portion (30c) of the screw member (30a) is connected to the first hole portion (5) in the hole (5) of the cutting insert. 5a) reaches the convex portion toward the central axis (A) and the first end face (2).
The cutting tool according to claim 13.