JP2021074839A - Cutting insert and processing method - Google Patents

Abstract

To provide a cutting insert and a processing method which can perform cutting processing as well as burnishing processing, and reduce processing time in the burnishing processing.SOLUTION: A cutting insert in a polygonal plate shape that is symmetrical with respect to a center line comprises a first cutting blade and a second cutting blade provided at outer edges on a polygonal surface pointing in directions different from each other, and a first flank face leading to the first cutting blade and a second flank face leading to the second cutting blade. The first cutting blade and the second cutting blade have corner blades respectively positioned at corner parts on the polygonal surface, and the first flank face and the second flank face have curved parts respectively extending along a plate thickness direction from the corner blades. At the curved part on the first flank face and at the curved part on the second flank face are provided a first slide- contact region and a second slide-contact region in which the insert is pressed against a surface to be cut of a material to be cut to perform burnishing processing, where the first slide-contact region and the second slide-contact region incline toward the center line as separating from the cutting blades along the thickness direction.SELECTED DRAWING: Figure 4

Description

The present invention relates to a cutting insert and a machining method.

In recent years, various improvements in mechanical properties have been required in order to realize higher performance of mechanical parts. In response to such demands, roller burnishing processing has been proposed in which the metal surface of the processed surface is pushed by a roller to improve the surface roughness and apply compressive residual stress. Non-Patent Document 1 proposes a method of adjusting the cutting edge position of a tool after turning and performing burnishing with a flank.

Manabu Iwai, Naoki Maeda, Kiyoshi Suzuki, "Vanishing using the flank of the turning tool nose", Proceedings of the 2015 Spring Meeting of the Japan Society for Precision Engineering, (2015), pp. 417-418

By using the insert described in Patent Document 1, it is possible to save time for replacing the cutting tool with the burnishing tool, and it is possible to improve the production efficiency. On the other hand, in such an insert, it is expected that the processing time of the burnishing process is further saved.

The present invention has been made in view of such circumstances, and provides a cutting insert and a processing method capable of performing burnishing in addition to cutting and further shortening the processing time of burnishing. I am aiming.

The cutting insert according to one embodiment of the present invention is a polygonal plate-shaped cutting insert symmetrical with respect to the center line, and has a rake surface provided on each of the pair of polygonal surfaces and an outer edge of one of the polygonal surfaces. A first cutting edge provided in the above, a second cutting edge provided on the outer edge of the other polygonal surface, a first flank surface connected to the first cutting edge, and a second flank surface connected to the second cutting edge. The first cutting edge and the second cutting edge each have a corner blade located at a corner portion of the polygonal surface, and the first flank surface and the second flank surface are from the corner blade. Each of the curved portions extending along the plate thickness direction is provided with a first sliding contact region for burnishing by being pressed against the cutting surface of the work material at the curved portion of the first flank surface. The curved portion of the second flank surface is provided with a second sliding contact region for burnishing by being pressed against the cutting surface of the work material, and the first sliding contact region is in the plate thickness direction. The second sliding contact region is inclined toward the center line as it is separated from the first cutting edge along the plate thickness direction, and is inclined toward the center line as it is separated from the second cutting edge along the plate thickness direction.

According to the above configuration, the cutting insert can burnish the cutting surface in the first and second sliding contact regions after the cutting process is performed. Further, according to the above configuration, the first sliding contact region and the second sliding contact region are inclined toward the center line side toward the center side in the plate thickness direction. Therefore, the first sliding contact region and the second sliding contact region are formed in a V shape when viewed from the side, and the first sliding contact region and the second sliding contact region are simultaneously formed on the outer peripheral surface of the work material. Can be contacted. As a result, it is possible to perform the burnishing process twice at the same time, and the processing time of the burnishing process can be shortened.

In the above-mentioned cutting insert, the radius of curvature of the first sliding contact region is larger than the radius of curvature of the corner blade of the first cutting edge, and the radius of curvature of the second sliding contact region is the said of the second cutting edge. The configuration may be larger than the radius of curvature of the corner blade.

According to the above configuration, the radius of curvature of the first and second sliding contact regions is larger than the radius of curvature of the corner blade connected to the flank where the sliding contact region is provided. By increasing the radius of curvature of the first and second sliding contact regions, the surface roughness of the machined surface after the burnishing process can be improved. Therefore, according to the present embodiment, the radius of curvature of the sliding contact region can be increased independently of the radius of curvature of the corner blade, and the surface roughness of the machined surface after the burnishing process can be improved. Generally, it is known that when the burnishing process is performed, the surface roughness can be improved by lowering the feed rate. According to the above configuration, by increasing the radius of curvature of the sliding contact region, it is possible to achieve a desired surface roughness even if the feed rate is increased, and the tact time of the burnishing process can be shortened.
The "radius of curvature of the corner blade" in the present specification is the radius of curvature of the corner blade in a virtual plane orthogonal to the plate thickness direction of the cutting insert, and means the so-called cutting edge R (or nose R). To do.
Similarly, the “radius of curvature of the sliding contact region” in the present specification is the radius of curvature of the sliding contact region in the cross section orthogonal to the plate thickness direction. Therefore, the radius of curvature of the sliding contact region may change depending on the position in the plate thickness direction. When the radius of curvature of the sliding contact region changes depending on the position in the plate thickness direction, the radius of curvature of the sliding contact region is larger than the radius of curvature of the corner blade at any position in the plate thickness direction.

In the above-mentioned cutting insert, the radius of curvature of the first sliding contact region continuously increases as the distance from the first cutting blade increases in the plate thickness direction, and the second sliding contact region is formed from the second cutting blade. The radius of curvature may be continuously increased as the distance from the plate thickness direction increases.

According to the above configuration, the radius of curvature of each sliding contact region increases as the distance from the radius of curvature of the corner blade connected to the flank where the sliding contact region is provided increases. Therefore, as compared with the case where a step is provided at the boundary portion of the sliding contact region, the rigidity of the cutting insert can be increased and damage to the cutting insert due to stress applied during machining can be suppressed.

In the above-mentioned cutting insert, the inclination angles of the first sliding contact region and the second sliding contact region with respect to the center line may be different from each other.

According to the above configuration, since the inclination angles of the first sliding contact region and the second inclined region are different from each other, the contact pressure of each sliding contact region with respect to the cutting surface can be made different from each other. Thereby, for example, in one burnishing process, it is possible to realize a process of gradually increasing the contact pressure.

One embodiment of the present invention is a machining method using the above-mentioned cutting insert, in which the first cutting edge is brought into contact with a work material rotating around a rotation axis to perform cutting to form a cutting surface. It has a step and a burnishing step of simultaneously pressing the first sliding contact region and the second sliding contact region against the cutting surface to perform burnishing.

According to the above configuration, the cutting process and the burnishing process can be continuously performed by using the above-mentioned cutting insert. Further, in the burnishing process, the first sliding contact area and the second sliding contact area can be brought into contact with the outer peripheral surface of the work material at the same time, and the processing time of the burnishing process can be shortened. That is, it is not necessary to change the tool attached to the jig of the machine tool from the tool for cutting to the tool for burnishing, and the manufacturing process can be shortened.

In the above-mentioned processing method, in the burnishing step, the cutting of one of the first sliding contact region and the second sliding contact region that first contacts the cutting surface of the rotating work material. The contact pressure with respect to the cutting surface of the other sliding contact region to be contacted later may be higher than the contact pressure with respect to the surface.

According to the above configuration, it is possible to perform the burnishing process in which the contact pressure is gradually increased in one burnishing process, and it is possible to enhance the effect of improving the surface roughness and applying the compressive residual stress.

According to the present invention, it is possible to provide a cutting insert and a processing method capable of performing a cutting process and a burnishing process and shortening the processing time of the burnishing process.

FIG. 1 is an exploded perspective view of the cutting edge replaceable cutting tool of one embodiment. FIG. 2 is a perspective view of the cutting insert of one embodiment. FIG. 3 is a diagram showing a cutting process using the cutting edge replaceable cutting tool of one embodiment. FIG. 4 is a diagram showing a burnishing process using the cutting edge replaceable cutting tool of one embodiment. FIG. 5 is an enlarged view of the vicinity of the cutting insert of FIG. FIG. 6 is a perspective view of a cutting insert of a modified example.

Hereinafter, the cutting insert 1 according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a cutting edge exchangeable cutting tool 30 having the cutting insert 1 of the present embodiment. The cutting edge replaceable cutting tool 30 is a cutting tool that performs a turning process on a work material made of a metal material that is rotated around a spindle.

The cutting edge replaceable cutting tool 30 has a cutting insert 1, a tool body 31 to which the cutting insert 1 is detachably mounted, a clamp mechanism (not shown) for attaching the cutting insert 1 to the tool body, and a seat member 35. ..

The tool body 31 is a rod body extending in a shaft shape. In the present specification, among the directions in which the tool body 31 extends, the direction toward the machined surface of the work material W is referred to as the tool tip side, and the opposite side is referred to as the tool base end side. Further, among the directions orthogonal to the extending direction of the tool body 31, each part will be described with the direction in which the polygonal surface 10 on which the first cutting edge 5A is provided faces as the upper side. It should be noted that the vertical direction in the present specification is merely a direction used for explanation, and does not limit the posture when the cutting edge replaceable cutting tool 30 is used.

The tool body 31 is made of a steel material or the like. The tool body 31 is detachably held by a jig (cutlery base) of a machine tool (not shown) at a base end portion 31b located on the tool base end side. Further, the jig holding the tool body 31 is fixed to a machine tool (lathe) such as a lathe (not shown).

The tip 31a of the tool body 31 is provided with an insert mounting seat 32 on which the cutting insert 1 is mounted. Further, the tip portion 31a of the tool body 31 may be provided with a coolant supply hole for supplying coolant to the cutting blades 5A and 5B of the cutting insert 1 mounted on the insert mounting seat 32.

The insert mounting seat 32 has a concave shape formed so as to correspond to the shape of the cutting insert 1. The cutting insert 1 arranged on the concave insert mounting seat 32 is fixed to the tool body 31 by a clamp mechanism (not shown). In the present embodiment, the insert mounting seat 32 has a triangular hole shape that opens toward the tool tip side and upward, while the cutting insert 1 is formed in a triangular plate shape.

The sheet member 35 is formed of, for example, a cemented carbide. The sheet member 35 has a triangular plate shape, corresponding to the cutting insert 1 being formed in a triangular plate shape. Of the front and back surfaces of the seat member 35, the back surface abuts on the bottom surface 32a of the insert mounting seat 32. Of the front and back surfaces of the seat member 35, the front surface is a mounting surface on which the cutting insert 1 is seated.

FIG. 2 is a perspective view of the cutting insert 1.
The cutting insert 1 has a polygonal plate shape (triangular plate shape in this embodiment) symmetrical with respect to the center line J. In the following description, the direction along the center line J may be simply referred to as the plate thickness direction.

The cutting insert 1 has a pair of polygonal surfaces 10 facing in the plate thickness direction and side surfaces 11 connecting the pair of polygonal surfaces 10. The cutting insert 1 of the present embodiment is a double-sided cutting insert in which cutting blades 5A and 5B are provided on the outer edges of both polygonal surfaces 10.

The cutting insert 1 is provided with a mounting hole 15 having a circular shape in a plan view, which penetrates in the plate thickness direction and opens in each of the pair of polygonal surfaces 10. The cutting insert 1 is fixed to the tool body 31 by a clamp mechanism (not shown) in the mounting hole 15 with one polygonal surface 10 facing the bottom surface 32a of the insert mounting seat 32. The seat member 35 is sandwiched between the cutting insert 1 and the bottom surface 32a of the insert mounting seat 32.

Further, the cutting insert 1 is provided on the tolerance ridge line between the rake face 7 provided on the pair of polygonal surfaces 10, the pair of flanks 8A and 8B provided on the side surface 11, and the rake face 7 and the flank 8A and 8B, respectively. It has cutting blades 5A and 5B, which are provided respectively. The pair of cutting edges 5A and 5B are classified into a first cutting edge 5A located on the outer edge of one polygonal surface 10 and a second cutting edge 5B located on the outer edge of the other polygonal surface 10. Similarly, the pair of flanks 8A and 8B are the first flank 8A located in the region on one polygonal surface 10 side and the second flank 8A located in the region on the other polygonal surface 10 side of the side surface 11. It is classified as a flank 8B.

The cutting insert 1 is made of a hard material such as cemented carbide. Of the outer surface of the cutting insert 1, at least the vicinity of the cutting edges 5A and 5B (cutting edges 5A and 5B, rake surface 7 and flank surfaces 8A and 8B) is covered with a hard film. The cutting insert 1 is fixed to the tool body 31 with a part of either one of the first cutting edge 5A and the second cutting edge 5B protruding from the tip portion 31a of the tool body 31. The cutting blades 5A and 5B perform cutting on the surface of the work material W that faces the radial direction of the rotation axis O or the end face that faces the axial direction.

The first cutting edge 5A and the second cutting edge 5B are provided on the outer edges of polygonal surfaces 10 that are different from each other. The first cutting edge 5A and the second cutting edge 5B of the present embodiment are provided over the entire length of the outer edge of the polygonal surface 10. However, the first cutting edge 5A and the second cutting edge 5B need only be provided at least in the corner portion of the outer edge of the polygonal surface 10.

The first cutting blade 5A and the second cutting blade 5B each have a corner blade 5a located at a corner portion of the polygonal surface 10 and a pair of straight blades 5b connected to both ends of the corner blade 5a and extending linearly. Have. The first cutting blade 5A and the second cutting blade 5B of the present embodiment have three corner blades 5a and three straight blades 5b connecting the pair of corner blades 5a to each other.

The rake face 7 is provided in a region near the cutting edges 5A and 5B in the entire area of the polygonal face 10. The rake face 7 extends in a band shape along the edge in the vicinity of the edge of the polygonal face 10. Further, the rake face 7 is a region where chips discharged when cutting is performed by the cutting blades 5A and 5B come into contact (scratch). The rake face 7 of the present embodiment is a flat surface orthogonal to the center line J. However, the rake face 7 may be a surface that inclines downward as it approaches the center line J side from the cutting blades 5A and 5B. The rake face 7 may be part of the breaker groove.

The first flank 8A is connected to the first cutting edge 5A. Further, the second flank 8B is connected to the second cutting edge 5B. The first flank surface 8A is arranged to face the work material W when the work material W is cut by the first cutting edge 5A. Similarly, the second flank surface 8B is arranged to face the work material W when the work material W is cut by the second cutting edge 5B.

The first flank surface 8A and the second flank surface 8B each divide the total length of the side surface 11 in the plate thickness direction into two. That is, the first flank surface 8A is located in the upper region of the total length of the side surface in the plate thickness direction, and the second flank surface 8B is located in the lower region.

The first flank surface 8A and the second flank surface 8B each have a curved portion 8a extending from the corner blade 5a along the plate thickness direction and a flat portion 8b extending from the straight blade 5b along the plate thickness direction. The curved portion 8a is a convex curved surface that is convex in the radial direction of the center line J. Further, the flat portion 8b is a flat surface parallel to the center line J.

A first sliding contact region 2A is provided on the curved portion 8a of the first flank surface 8A. The first sliding contact region 2A is a region that is a part of the curved portion 8a of the first flank surface 8A and is separated downward from the corner blade 5a of the first cutting blade 5A in the plate thickness direction. In the present embodiment, the first sliding contact region 2A is provided over the entire length of the curved portion 8a in the plate thickness direction.

The radius of curvature R of the first sliding contact region 2A continuously increases as it is separated from the first cutting edge 5A in the plate thickness direction. That is, the first sliding contact region 2A is a conical surface that tapers toward the upper side. The radius of curvature of the upper end of the first sliding contact region 2A coincides with the radius of curvature r of the corner blade 5a. Therefore, the first sliding contact region 2A is inclined toward the center line J as it is separated from the first cutting edge 5A along the plate thickness direction.

As described above, the radius of curvature R of the first sliding contact region 2A increases as it is separated from the first cutting edge 5A in the plate thickness direction, and the radius of curvature of the upper end of the first sliding contact region 2A is the corner blade 5a. It coincides with the radius of curvature r. Therefore, the radius of curvature R of the first sliding contact region 2A is larger than the radius of curvature r of the corner blade 5a. That is, in the present embodiment, the radius of curvature R of the first sliding contact region 2A changes depending on the position in the plate thickness direction, but is larger than the radius of curvature r of the corner blade 5a at any position in the plate thickness direction.
Here, the radius of curvature R of the first sliding contact region 2A means the radius of curvature of the first sliding contact region 2A in a cross section orthogonal to the plate thickness direction.

The second flank 8B has a shape symmetrical with respect to the first flank 8A. Therefore, the second flank 8B has the same configuration as the first flank 8A. That is, the curved portion 8a of the second flank surface 8B is provided with the second sliding contact region 2B. The radius of curvature R of the second sliding contact region 2B continuously increases as it is separated from the second cutting edge 5B in the plate thickness direction. The second sliding contact region 2B is inclined toward the center line J as it is separated from the second cutting edge 5B along the plate thickness direction. The radius of curvature R of the second sliding contact region 2B is larger than the radius of curvature r of the corner blade 5a.

The first sliding contact region 2A and the second sliding contact region 2B are burnished by being pressed against the cutting surface Wa of the work material W. The surfaces of the first sliding contact region 2A and the second sliding contact region 2B are coated with a coating film suitable for burnishing. This film is formed by means such as a CVD coating film.

Next, a machining method using the cutting insert 1 of the present embodiment will be described with reference to FIGS. 3 to 5.
In the processing method of the present embodiment, cutting processing and burnishing processing are sequentially performed on the outer peripheral surface of the columnar work material W. Both the cutting step and the burnishing step of the present embodiment are performed using a lathe. The cutting step and the burnishing step of the present embodiment are performed while rotating the work material W around the rotation axis O.

FIG. 3 is a diagram showing a cutting process using the cutting edge replaceable cutting tool 30.
In the cutting process of the present embodiment, the outer peripheral surface of the work material W facing the radial outer side of the rotation axis O is cut. Here, a case where cutting is performed using the first cutting edge 5A among the pair of cutting edges 5A and 5B will be described.

In the cutting process, the operator puts the cutting insert 1 in a state where the rake face 7 on which the first cutting blade 5A is provided faces the rotation direction of the work material W, and uses the cutting edge replaceable tool 30 on the lathe tool post ( Attach to the jig).

Further, the operator operates the tool post to move the blade edge exchange type cutting tool 30 and brings the corner blade 5a of the first cutting edge 5A into contact with the outer peripheral surface of the work material W rotating around the rotation axis O. Next, the operator moves the first cutting edge 5A in the axial direction of the rotating axis O without changing the position and posture of the first cutting edge 5A in the radial direction of the rotating axis O. As a result, the outer peripheral surface of the work material W is cut by the first cutting edge 5A to form the cutting surface Wa. The operator moves the cutting edge exchangeable cutting tool 30 to the outside in the radial direction of the rotary axis O after the cutting surface Wa having a sufficient length in the axial direction of the rotary axis O is formed. As a result, the first cutting edge 5A is separated from the work material W, and the cutting process is completed.

FIG. 4 is a diagram showing a burnishing process using the cutting edge replaceable cutting tool 30. Further, FIG. 5 is an enlarged view of the vicinity of the cutting insert 1 of FIG.
The burnishing step is performed immediately after the cutting step. More specifically, the burnishing step can be continuously performed after the cutting step without stopping the rotation of the work material W.

In the burnishing step, the operator first moves the cutting edge exchangeable cutting tool 30 so that the first sliding contact area 2A and the second sliding contact area 2B face each other in the radial direction of the cutting surface Wa and the rotation axis O. More specifically, the cutting edge exchangeable cutting tool 30 is moved so that the rotation axis O is located on the center line of the angle formed by the first sliding contact region 2A and the second sliding contact region 2B. Further, the operator moves the cutting edge replaceable cutting tool 30 inward in the radial direction of the rotation axis O, and simultaneously presses the first sliding contact region 2A and the second sliding contact region 2B against the cutting surface Wa to perform burnishing. ..

The degree of contact (pressing amount) of the first sliding contact area 2A and the second sliding contact area 2B may be different from each other. More specifically, the center line of the angle formed by the first sliding contact region 2A and the second sliding contact region 2B is positioned slightly above the line extending in the radial direction from the center line of the work material W. .. As a result, the contact pressure on the cutting surface Wa in the second sliding contact region 2B located on the lower side is higher than the contact pressure on the cutting surface Wa in the first sliding contact region 2A located on the upper side. That is, of the first sliding contact region 2A and the second sliding contact region 2B, one of the sliding contact regions that first contacts the cutting surface Wa of the rotating work material W comes into contact after the contact pressure with respect to the cutting surface Wa. The contact pressure of the other sliding contact region with respect to the cutting surface Wa is increased. As a result, the cutting surface Wa of the work material W is burnished at a low contact pressure and then burnished again at a high contact pressure. As a result, it is possible to perform the burnishing process in which the contact pressure is gradually increased in one burnishing process, and it is possible to enhance the effect of improving the surface roughness and applying the compressive residual stress.
Further, the inclination angle between the first sliding contact region 102A and the second sliding contact region 102B may be changed as in the cutting insert 101 of the modified example shown in FIG. That is, the inclination angles of the first sliding contact region 102A and the second sliding contact region 102B with respect to the center line J are different from each other. In this case, in the burnishing step, the contact pressure in the first sliding contact region 102A and the second sliding contact region 102B can be adjusted without finely adjusting the position of the cutting insert 101.

In the burnishing step, the first sliding contact region 2A and the second sliding contact region 2B are pressed against the cutting surface Wa, so that the unevenness formed on the cutting surface Wa is plastically deformed. Thereby, the surface roughness of the processed surface of the work material W after the burnishing process can be improved. In addition, compressive residual stress can be applied to the surface of the work material W to increase the hardness of the machined surface of the work material W after the burnishing process.

According to the present embodiment, after cutting with the first cutting edge 5A, the cutting surface Wa can be burnished in the first sliding contact region 2A and the second sliding contact region 2B. Therefore, in the machining procedure, it is not necessary to replace the tool for performing the cutting process with the tool for performing burnishing, and the tact time at the time of manufacturing can be shortened to reduce the manufacturing cost.

According to the present embodiment, the first sliding contact region 2A and the second sliding contact region 2B are inclined toward the center line J side toward the center side in the plate thickness direction. Therefore, the first sliding contact region 2A and the second sliding contact region 2B are formed in a V shape when viewed from the side. Therefore, the first sliding contact region 2A and the second sliding contact region 2B can be brought into contact with the outer peripheral surface of the work material W at the same time. As a result, it is possible to perform the two burnishing processes at the same time, and the processing time of the burnishing process can be shortened.

According to the present embodiment, the radius of curvature of the first sliding contact region 2A and the second sliding contact region 2B is larger than the radius of curvature of the corner blade 5a connected to the flanks 8A and 8B where the sliding contact region is provided. By increasing the radius of curvature of the first sliding contact region 2A and the second sliding contact region 2B, the surface roughness of the machined surface after the burnishing process can be improved. Therefore, according to the present embodiment, the radius of curvature of the first sliding contact region 2A and the second sliding contact region 2B can be increased without depending on the radius of curvature of the corner blade 5a, and the machined surface after burnishing can be increased. The surface roughness can be improved. Generally, it is known that when the burnishing process is performed, the surface roughness can be improved by lowering the feed rate. According to the above configuration, by increasing the radius of curvature of the first sliding contact region 2A and the second sliding contact region 2B, it is possible to achieve the desired surface roughness even if the feed rate is increased, and the burnishing process is performed. Tact time can be shortened.

According to the present embodiment, the radius of curvature of the first sliding contact region 2A and the second sliding contact region 2B increases as the distance from the radius of curvature of the corner blade 5a connected to the flanks 8A and 8B where the sliding contact region is provided increases. .. Therefore, as compared with the case where a step is provided at the boundary between the first sliding contact region 2A and the second sliding contact region 2B, the rigidity of the cutting insert 1 is increased and the cutting insert 1 is damaged due to the stress applied during machining. Can be suppressed.

Although the embodiments of the present invention have been described above, the configurations and combinations thereof in the above-described embodiments are examples, and the configurations are added, omitted, replaced, and the like without departing from the spirit of the present invention. Can be changed. Further, the present invention is not limited to the embodiments.

For example, in the above-described embodiment, the cutting insert 1 is formed in the shape of a triangular plate, but the present invention is not limited to this. That is, the cutting insert 1 of the present invention may have another shape such as a rectangular plate as long as it has a polygonal plate shape.

1 ... Cutting insert 2A ... 1st sliding contact area 2B ... 2nd sliding contact area 5a ... Corner blade 5A ... 1st cutting blade 5B ... 2nd cutting blade 7 ... Scooping surface 8a ... Curved part 8A ... 1st flank surface 8B ... 2nd flank surface 10 ... Polygonal surface J ... Center line O ... Rotation axis r, R ... Radius of curvature W ... Work material Wa ... Cutting surface

Claims (6)

A polygonal plate-shaped cutting insert that is symmetrical with respect to the center line.
A rake face provided on each of the pair of polygonal faces,
A first cutting edge provided on the outer edge of one of the polygonal surfaces and a second cutting edge provided on the outer edge of the other polygonal surface.
A first flank surface connected to the first cutting edge and a second flank surface connected to the second cutting edge are provided.
The first cutting edge and the second cutting edge each have a corner blade located at a corner portion of the polygonal surface.
The first flank surface and the second flank surface each have a curved portion extending from the corner blade in the plate thickness direction.
The curved portion of the first flank surface is provided with a first sliding contact region for burnishing by being pressed against the cutting surface of the work material.
The curved portion of the second flank surface is provided with a second sliding contact region for burnishing by being pressed against the cutting surface of the work material.
The first sliding contact region is inclined toward the center line as it is separated from the first cutting edge along the plate thickness direction.
The second sliding contact region is inclined toward the center line as it is separated from the second cutting edge along the plate thickness direction.
Cutting insert. The radius of curvature of the first sliding contact region is larger than the radius of curvature of the corner blade of the first cutting edge.
The radius of curvature of the second sliding contact region is larger than the radius of curvature of the corner blade of the second cutting edge.
The cutting insert according to claim 1. The radius of curvature of the first sliding contact region continuously increases as the distance from the first cutting edge increases in the plate thickness direction.
The radius of curvature of the second sliding contact region continuously increases as the distance from the second cutting edge increases in the plate thickness direction.
The cutting insert according to claim 1. The inclination angles of the first sliding contact region and the second sliding contact region with respect to the center line are different from each other.
The cutting insert according to any one of claims 1 to 3. A processing method using the cutting insert according to any one of claims 1 to 4.
A cutting process in which the first cutting edge is brought into contact with a work material rotating around a rotation axis to perform cutting to form a cutting surface.
It has a burnishing step of simultaneously pressing the first sliding contact region and the second sliding contact region against the cutting surface to perform burnishing.
Processing method. In the burnishing step, the contact pressure of one of the first sliding contact region and the second sliding contact region that first contacts the cutting surface of the rotating work material with respect to the cutting surface is determined. Increasing the contact pressure of the other sliding contact area that comes into contact later with respect to the cutting surface.
The processing method according to claim 5.

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