JP2020157393A - Cutting tool - Google Patents

Abstract

To provide a cutting tool that can be enhanced in strength of a blade edge of a blade part and further can be improved in chip processability.SOLUTION: A cutting tool 10 comprises a blade part 12 made of a cBN sintered body or a diamond sintered body. A rake face 1 has a groove part 4 extending along a cutting blade 3 and a land part 5 arranged between the cutting blade 3 and the groove part 4. The groove part 4 has a bottom part 6, and a first side wall part 7 and a second side wall part 8 oppositely arranged with an interval from each other in a groove width direction of the groove part 4. The first side wall part 7 is positioned between the bottom part 6 and the land part 5 in the groove width direction, and the first side wall part 7 has a protruding part 13 formed in a convex shape in a cross sectional view crossing the cutting blade 3. The protruding part 13 is pointed from the first side wall part 7 to the second side wall part 8 side in the groove width direction and from the bottom part 6 to an opening part side in a groove depth direction, and the second side wall part 8 extends obliquely from the second side wall part 8 toward the first side wall part 7 side in the groove width direction, as going from the bottom part 6 toward the opening part side in the groove depth direction or extends along the groove depth direction.SELECTED DRAWING: Figure 4

Description

The present invention relates to a cutting tool.

Conventionally, for example, cutting tools such as the throw-away insert described in Patent Document 1 are known. The throw-away insert of Patent Document 1 includes a main body and a blade portion having a cutting edge. The blade portion includes a land surface extending along the cutting edge and a tip breaker having a recess.

International Publication No. 2016/03549

With conventional cutting tools, there is room for improvement in that the strength of the cutting edge of the cutting edge is increased to suppress chipping and chipping, and that chips are easily separated to improve chip dispersibility.

In view of the above circumstances, one of the objects of the present invention is to provide a cutting tool capable of increasing the cutting edge strength of the blade portion and improving the chip controllability.

One aspect of the present invention is a cutting tool including a blade portion made of a cBN sintered body or a diamond sintered body, wherein the blade portion includes a rake face, a flank surface, a rake face, and the flank surface. The rake face has a cutting edge formed on the intersecting ridgeline of the above, and the rake face is arranged between the groove portion extending along the cutting edge and the cutting edge and the groove portion, and is formed on the cutting edge and the groove portion. It has a land portion extending along the groove portion, and the groove portions are arranged so as to face each other with a space between the bottom portion and the groove width direction of the groove portion, and from both ends of the bottom portion in the groove width direction to the groove width direction. It has a first side wall portion and a second side wall portion extending from the bottom portion toward the opening side of the groove portion in the groove depth direction orthogonal to the above, and the first side wall portion is the bottom portion in the groove width direction. The first side wall portion is located between the land portion and the land portion, and the first side wall portion has a convex portion having a convex shape in a cross-sectional view intersecting the cutting edge, and the convex portion is the first portion in the groove width direction. From the side wall portion to the second side wall portion side and from the bottom portion in the groove depth direction to the opening side, the second side wall portion faces from the bottom portion in the groove depth direction to the opening side. Therefore, it extends inclinely from the second side wall portion in the groove width direction toward the first side wall portion side, or extends along the groove depth direction.

According to the present invention, since the first side wall portion of the groove portion has a convex portion, a large wall thickness is secured in the portion of the blade portion between the first side wall portion including the cutting edge and the flank. As a result, the strength of the cutting edge of the cutting edge is increased, and chipping, chipping, and the like are suppressed.
Further, the chips generated during the cutting process are guided from the cutting edge onto the land portion into the groove portion, so that the chips are easily curled. Then, the second side wall portion is inclined from the second side wall portion in the groove width direction toward the first side wall portion side as it goes from the bottom portion in the groove depth direction toward the opening side, or along the groove depth direction. Since it is extended, the chips are likely to hit the second side wall portion and be divided easily, and the chips are prevented from extending for a long time. Therefore, the chip disposal property is improved.

In the cutting tool, the angle at which the second side wall portion is inclined with respect to the groove depth direction is preferably 10 ° or less.

When the angle at which the second side wall is inclined with respect to the groove depth direction is 10 ° or less, the chips are separated by the second side wall, and the chips are stably discharged to the outside of the groove, and the inside of the groove is formed. Clogged chips can be suppressed.

In the cutting tool, the convex portion preferably has a convex curved first convex curved surface portion connected to the land portion.

In this case, the portion where the chips are scraped is easily dispersed in the first convex curved surface portion, and the concentration of the force on the predetermined portion in the convex portion is suppressed. Therefore, the strength of the cutting edge of the cutting edge can be increased more stably.

In the cutting tool, it is preferable that the radius of curvature of the first convex curved surface portion is 0.05 mm or more and 0.2 mm or less in a cross-sectional view intersecting the cutting edge.

When the radius of curvature of the first convex curved surface portion is 0.05 mm or more, it is possible to prevent the connection portion between the first convex curved surface portion and the first side wall portion connected to the first convex curved surface portion from becoming an acute angle. Therefore, the cutting edge defect can be suppressed.
Further, when the radius of curvature of the first convex curved surface portion is 0.2 mm or less, chips can be stably curled by the convex curved surface portion of the first convex curved surface portion while improving the fracture resistance of the cutting edge.

In the cutting tool, the convex portion preferably has a convex curved second convex curved surface portion arranged between the first convex curved surface portion and the bottom portion.

In this case, the portion where the chips are scraped is easily dispersed in the second convex curved surface portion, and the concentration of the force on the predetermined portion in the convex portion is suppressed. Therefore, the strength of the cutting edge of the cutting edge can be increased more stably.
Further, by variously combining the shapes and sizes of the first convex curved surface portion and the second convex curved surface portion, the degree of freedom in the shape of the convex portion (breaker shape) is increased.

In the cutting tool, the convex portion is preferably arranged between the first convex curved surface portion and the second convex curved surface portion, and has a connecting surface portion that intersects the cutting edge and forms a linear shape in a cross-sectional view. ..

In this case, the degree of freedom in the shape of the convex portion is further increased by variously combining the shapes and sizes of the first convex curved surface portion and the second convex curved surface portion with the inclination angle and size of the connecting surface portion. Be done.

In the cutting tool, the convex portion is formed in a convex shape by combining a plurality of inclined surfaces having different inclinations with respect to a reference surface perpendicular to the groove depth direction, and the plurality of inclined surfaces are formed on the cutting edge. They may be formed in a straight line in the cross-sectional view at which they intersect.

In this case, the degree of freedom in the shape of the convex portion is increased.

In the cutting tool, the land portion is inclined from the opening in the groove depth direction toward the bottom side as it goes from the first side wall portion in the groove width direction toward the second side wall portion side. It is preferable that the angle at which the land portion is inclined with respect to the reference plane that extends and is perpendicular to the groove depth direction is 30 ° or less.

In this case, since the land portion inclines and extends from the opening in the groove depth direction toward the bottom side as the distance from the cutting edge in the groove width direction increases, the rake angle of the cutting edge is regarded as a positive angle, and the sharpness is enhanced. Be done. Therefore, the machined surface of the work material can be finished with good surface roughness with high accuracy.
Since the angle at which the land portion is inclined with respect to the reference plane perpendicular to the groove depth direction is 30 ° or less, it is possible to prevent the cutting edge blade angle from becoming too small and stabilize the cutting edge strength of the cutting edge. Can be enhanced.

In the cutting tool, the length of the land portion in the groove width direction is preferably 0.05 mm or more and 0.2 mm or less.

When the length of the land portion in the groove width direction is 0.05 mm or more, the strength of the cutting edge can be ensured, so that the cutting edge defect can be suppressed.
When the length of the land portion in the groove width direction is 0.2 mm or less, the area (region) where the chips come into contact with the land portion is suppressed to be small, the cutting resistance is reduced, and the machining is stable.

In the cutting tool, the length of the land portion in the groove depth direction between the end portion on the side of the first side wall portion and the second side wall portion in the groove width direction and the bottom portion is 0. It is preferably 1 mm or more and 0.3 mm or less.

If the length in the groove depth direction between the land portion and the bottom portion is 0.1 mm or more, the chips are stably curled when they enter the groove portion, and are stable when they hit the second side wall portion. Divided.
When the length in the groove depth direction between the land portion and the bottom portion is 0.3 mm or less, chips that have entered the groove portion are suppressed from staying in the groove portion, and chip clogging is suppressed. As a result, the cutting edge defect can be suppressed.

In the cutting tool, the length of the bottom portion in the groove width direction is preferably 0.1 mm or more and 0.3 mm or less.

When the length of the bottom portion in the groove width direction is 0.1 mm or more, the chips that have entered the groove portion stably hit the second side wall portion, and the chips are more easily divided.
When the length of the bottom portion in the groove width direction is 0.3 mm or less, chips are suppressed from accumulating in the groove portion, and the tool is suppressed from being chipped.

According to the cutting tool of one aspect of the present invention, the cutting edge strength of the cutting edge portion can be increased and the chip controllability can be improved.

It is a perspective view which shows the cutting tool of 1st Embodiment of this invention. It is a perspective view which shows the blade part of the cutting tool of FIG. 1 enlarged. It is a top view (plan view) which shows the blade part of the cutting tool of 1st Embodiment in an enlarged manner. FIG. 6 is a sectional view taken along line IV-IV of the blade portion of FIG. It is sectional drawing which shows the deformation example of the blade part of the cutting tool of 1st Embodiment. It is a perspective view which shows the cutting tool of the 2nd Embodiment of this invention. FIG. 6 is an enlarged perspective view showing a blade portion of the cutting tool of FIG. It is sectional drawing of the blade part of the cutting tool of 2nd Embodiment. It is a perspective view which shows the modification of the cutting tool of 2nd Embodiment. 9 is an enlarged perspective view showing a blade portion of the cutting tool of FIG. 9.

<First Embodiment>
Hereinafter, the cutting tool 10 of the first embodiment of the present invention will be described with reference to FIGS. 1 to 5.
The cutting tool 10 of the present embodiment is a cutting insert used for a cutting edge replaceable cutting tool for turning a metal work material. The work material is, for example, high hardness steel or the like. Although not particularly shown, the cutting edge replaceable cutting tool includes a holder and a cutting tool (cutting insert) 10. The holder is made of steel, for example. The holder has an insert mounting seat at the tip of the holder. The cutting tool 10 is detachably fixed to the insert mounting seat.

As shown in FIG. 1, the cutting tool 10 has a plate shape. In the present embodiment, the cutting tool 10 has a polygonal plate shape, specifically, a triangular plate shape. That is, the cutting tool 10 has a triangular shape in a plan view. However, the cutting tool 10 may be, for example, a quadrangular plate such as a rhombus in a plan view.

The cutting tool 10 includes a base metal portion 11 and a blade portion 12.
The base metal portion 11 is made of, for example, a cemented carbide. The base metal portion 11 has a concave blade portion mounting portion 11a. The blade portion 12 is fixed to the blade portion mounting portion 11a by joining or the like. The blade portion 12 is arranged at the corner portion of the cutting tool 10. The blade portion 12 is made of a cBN sintered body or a diamond sintered body. The cBN sintered body is a sintered body containing cBN and a binder. The diamond sintered body is a sintered body containing diamond and a binder.

When the blade portion 12 is made of a cBN sintered body, the cBN content of the blade portion 12 is, for example, 20% by volume or more and 80% by volume or less. Preferably, the cBN content of the blade portion 12 is 40% by volume or more. As the binder, at least one selected from the group consisting of nitrides, carbides, borides, oxides and solid solutions of these elements of Group 4a, 5a and 6a of the Periodic Table, and aluminum nitrides, borides and oxidations. A binder having a composition consisting of at least one selected from the group consisting of a substance and a solid solution thereof can be used.
When the blade portion 12 is made of a diamond sintered body, the diamond content of the blade portion 12 is, for example, 80% by volume or more.

As shown in FIGS. 1 to 4, the blade portion 12 has a rake face 1, a flank surface 2, and a cutting edge 3 formed on an intersecting ridge line between the rake face 1 and the flank surface 2.
The rake face 1 is arranged between the groove portion 4 extending along the cutting edge 3 and the cutting edge 3 and the groove portion 4, and has a land portion 5 extending along the cutting edge 3 and the groove portion 4 and a flat surface 9. Have.
The groove portion 4 has a bottom portion 6 and a first side wall portion 7 and a second side wall portion 8 which are arranged so as to face each other at intervals in the groove width direction of the groove portion 4.
The shape of the rake face 1 of the blade portion 12 is formed by laser processing. Specifically, in the present embodiment, the groove portion 4 forming the breaker shape of the blade portion 12 is formed by engraving a part of the flat surface 9 by laser processing. The land portion 5 and other portions of the blade portion 12 may be formed by laser processing.

[Definition of direction]
In this embodiment, the XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system in each figure. In the cross-sectional view intersecting the cutting edge 3 shown in FIG. 4, the groove width direction of the groove portion 4 corresponds to the Y-axis direction. Of the groove width directions of the groove portion 4, the direction from the second side wall portion 8 to the first side wall portion 7 is the direction from the second side wall portion 8 in the groove width direction to the first side wall portion 7 side, or the outside of the insert in the groove width direction. Call. Of the groove width directions of the groove portion 4, the direction from the first side wall portion 7 to the second side wall portion 8 is the direction from the first side wall portion 7 to the second side wall portion 8 side in the groove width direction, or the inside of the insert in the groove width direction. Call.

In FIG. 4, the groove depth direction of the groove portion 4 corresponds to the Z-axis direction. The groove depth direction is a direction orthogonal to the groove width direction. Of the groove depth directions of the groove portion 4, the direction from the bottom portion 6 to the opening portion of the groove portion 4 is referred to as the opening side from the bottom portion 6 in the groove depth direction or the upper side in the groove depth direction. Of the groove depth directions of the groove portion 4, the direction from the opening of the groove portion 4 to the bottom portion 6 is referred to as the side from the opening in the groove depth direction to the bottom portion 6 side or the lower side in the groove depth direction.

[Cutting edge]
As shown in FIGS. 2 and 3, the cutting edge 3 has a corner edge portion 3a and a straight edge portion 3b. The corner blade portion 3a has a convex curved shape. In the present embodiment, the corner blade portion 3a has a convex curved shape protruding outward of the insert in the groove width direction, and in FIG. 3, it protrudes in the X-axis direction. The straight blade portion 3b is connected to the corner blade portion 3a and extends linearly. In the present embodiment, a pair of straight blade portions 3b are connected to both ends of the corner blade portion 3a in the blade length direction. The set of the corner blade portion 3a and the pair of straight blade portions 3b (that is, the cutting edge 3) is substantially V-shaped as a whole.

[Scooping surface]
The rake face 1 faces upward in the groove depth direction.
As shown in FIG. 3, the land portion 5 has a substantially V shape as a whole in a plan view. Of the land portion 5, a portion adjacent to the corner blade portion 3a, that is, a portion adjacent to the inside of the insert in the groove width direction with respect to the corner blade portion 3a extends in a curved shape. Of the land portion 5, a portion adjacent to the straight blade portion 3b, that is, a portion adjacent to the inside of the insert in the groove width direction with respect to the straight blade portion 3b extends linearly.

In the present embodiment, the length (land width) L of the land portion 5 in the groove width direction is substantially constant along the direction in which the land portion 5 extends. In FIG. 4, the length L of the land portion 5 in the groove width direction is, for example, 0.05 mm or more and 0.2 mm or less.
As shown in FIG. 4, in the present embodiment, the land portion 5 has a planar shape extending in a direction perpendicular to the groove depth direction. That is, the land portion 5 is parallel to the reference plane RP perpendicular to the groove depth direction.

As shown in FIG. 3, the groove portion 4 has a substantially V shape as a whole in a plan view. Of the groove portion 4, the portion of the corner blade portion 3a located inside the insert in the groove width direction extends in a curved shape. Of the groove portion 4, the portion of the straight blade portion 3b located inside the insert in the groove width direction extends linearly.

In FIG. 4, the length W of the bottom portion 6 in the groove width direction is, for example, 0.1 mm or more and 0.3 mm or less. Groove depth between the end of the land portion 5 on the side from the first side wall portion 7 to the second side wall portion 8 in the groove width direction (the end inside the insert in the groove width direction of the land portion 5) and the bottom portion 6. The length D in the direction (first groove depth of the groove portion 4) is, for example, 0.1 mm or more and 0.3 mm or less. The end of the land portion 5 inside the insert in the groove width direction is connected to the upper end of the first side wall portion 7 in the groove depth direction. Therefore, the first groove depth D may be rephrased as the length in the groove depth direction between the upper end portion of the first side wall portion 7 in the groove depth direction and the bottom portion 6.

The length H in the groove depth direction (second groove depth of the groove portion 4) between the bottom portion 6 of the groove portion 4 and the flat surface 9 is, for example, 0.15 mm or more and 0.2 mm or less. The second groove depth H may be rephrased as the total length of the second side wall portion 8 in the groove depth direction.

The bottom portion 6 is a wall portion located on the lower side in the groove depth direction in the groove portion 4. The bottom portion 6 has a planar shape extending in a direction perpendicular to the groove depth direction. That is, the bottom portion 6 is parallel to the reference plane RP. The first side wall portion 7 and the second side wall portion 8 extend from both ends of the bottom portion 6 in the groove width direction from the bottom portion 6 in the groove depth direction to the opening side of the groove portion 4 (that is, the upper side in the groove depth direction).

The first side wall portion 7 is located between the bottom portion 6 and the land portion 5 in the groove width direction. The first side wall portion 7 is located between the bottom portion 6 and the land portion 5 also in the groove depth direction. The first side wall portion 7 is connected to an end portion inside the insert in the groove width direction of the land portion 5 and an end portion outside the insert in the groove width direction of the bottom portion 6.
The first side wall portion 7 has a convex portion 13 and an inclined surface portion 14.

As shown in FIG. 4, the convex portion 13 has a convex shape in a cross-sectional view intersecting the cutting edge 3. The convex portion 13 faces from the first side wall portion 7 in the groove width direction to the second side wall portion 8 side and from the bottom portion 6 in the groove depth direction to the opening side. That is, the convex portion 13 faces the inside of the insert in the groove width direction and the upper side in the groove depth direction.
In the present embodiment, the convex portion 13 has a convex curved first convex curved surface portion 13a connected to the land portion 5. The outer end of the insert in the groove width direction of the first convex curved surface portion 13a (the upper end in the groove depth direction) is connected to the inner end of the insert in the groove width direction of the land portion 5. The end inside the insert in the groove width direction of the first convex curved surface portion 13a (lower end in the groove depth direction) is the upper end in the groove depth direction of the inclined surface portion 14 (outside the insert in the groove width direction). Connect with the end). In the cross-sectional view shown in FIG. 4, the first convex curved surface portion 13a has a convex curved shape. As shown in FIG. 4, the radius of curvature of the first convex curved surface portion 13a is, for example, 0.05 mm or more and 0.2 mm or less in a cross-sectional view intersecting the cutting edge 3.

The inclined surface portion 14 is connected to the end portion of the convex portion 13 inside the insert in the groove width direction. The inclined surface portion 14 is connected to the lower end portion of the convex portion 13 in the groove depth direction. The inclined surface portion 14 inclines and extends toward the inside of the insert in the groove width direction toward the lower side in the groove depth direction. As shown in FIG. 3, the portion 14a of the inclined surface portion 14 located inside the insert in the groove width direction of the corner blade portion 3a has a concave curved surface shape (concave tapered surface shape). Of the inclined surface portion 14, the portion 14b of the straight blade portion 3b located inside the insert in the groove width direction is flat. The lower end of the inclined surface portion 14 in the groove depth direction is connected to the outer end of the insert in the groove width direction of the bottom portion 6.

As shown in FIG. 4, the second side wall portion 8 is inclined from the second side wall portion 8 in the groove width direction toward the first side wall portion 7 side from the bottom portion 6 in the groove depth direction toward the opening side. Extend or extend along the groove depth direction. The angle α at which the second side wall portion 8 is inclined with respect to the groove depth direction is 10 ° or less.

As shown in FIG. 2, in the present embodiment, the portion 8a of the second side wall portion 8 located inside the insert in the groove width direction of the corner blade portion 3a is oriented in the groove width direction toward the upper side in the groove depth direction. It slopes and extends toward the outside of the insert.
Further, of the second side wall portion 8, the portion 8b of the straight blade portion 3b located inside the insert in the groove width direction is a portion that inclines and extends toward the outside of the insert in the groove width direction toward the upper side in the groove depth direction. It has 8b1 and a portion 8b2 extending along the groove depth direction. In the illustrated example, of the portion 8b of the second side wall portion 8 located inside the insert in the groove width direction of the straight blade portion 3b, the portion 8b is located closer to the corner blade portion 3a than the recess 15 described later along the direction in which the groove portion 4 extends. In the portion 8b1, the second side wall portion 8 is inclined and extends toward the outside of the insert in the groove width direction toward the upper side in the groove depth direction. Further, of the portion 8b of the second side wall portion 8 located inside the insert of the straight blade portion 3b in the groove width direction, the portion 8b2 located on the side opposite to the corner blade portion 3a from the recess 15 along the direction in which the groove portion 4 extends. Then, the second side wall portion 8 extends along the groove depth direction.

In the present embodiment, the second side wall portion 8 is configured by connecting a plurality of planes arranged along the direction in which the groove portion 4 extends.
As shown in FIGS. 2 and 3, in the present embodiment, the second side wall portion 8 has the recess 15. The recess 15 has a concave shape that is recessed from the second side wall portion 8 to the inside of the insert in the groove width direction. In the illustrated example, the recess 15 is arranged in each of the second side wall portions 8 b located inside the insert in the groove width direction of the pair of straight blade portions 3b. That is, a plurality of recesses 15 (two in this embodiment) are provided in the second side wall portion 8. The recess 15 is formed by connecting two planes having different inclinations in a direction in which the groove 4 extends.

The flat surface 9 is located on the rake surface 1 inside the insert in the groove width direction with respect to the groove portion 4. As shown in FIG. 4, the flat surface 9 is a flat surface extending in a direction perpendicular to the groove depth direction. That is, the flat surface 9 is parallel to the reference surface RP.

[Escape surface]
The flank 2 is arranged on the outer peripheral surface of the blade portion 12. The flank 2 faces the outside of the insert in the groove width direction. In the present embodiment, the flank 2 extends inclinely toward the inside of the insert in the groove width direction from the cutting edge 3 toward the lower side in the groove depth direction.
As shown in FIG. 2, the flank 2 has a first flank portion 2a and a second flank portion 2b.

The first flank surface portion 2a is connected to the corner blade portion 3a in the groove depth direction. The first flank surface portion 2a is arranged on the lower side of the corner blade portion 3a in the groove depth direction. The first flank surface portion 2a has a convex curved surface shape that protrudes toward the outside of the insert in the groove width direction. Although not particularly shown, the first flank surface portion 2a has a convex curved shape in a cross-sectional view perpendicular to the groove depth direction.

The second flank surface portion 2b is connected to the straight blade portion 3b in the groove depth direction. The second flank surface portion 2b is arranged below each of the pair of straight blade portions 3b in the groove depth direction. That is, a pair of second flanks 2b are provided. The second flank surface portion 2b is flat.

[Action and effect according to this embodiment]
According to the cutting tool 10 of the present embodiment described above, since the first side wall portion 7 of the groove portion 4 has the convex portion 13, the first side wall portion 7 including the cutting edge 3 and the flank 2 of the blade portions 12 A large wall thickness is secured between the two. As a result, the strength of the cutting edge of the blade portion 12 is increased, and chipping, chipping, and the like are suppressed.
Further, the chips generated during the cutting process are guided from the cutting edge 3 over the land portion 5 into the groove portion 4, so that the chips are easily curled. Then, the second side wall portion 8 is inclined from the second side wall portion 8 in the groove width direction toward the first side wall portion 7 side as it goes from the bottom portion 6 in the groove depth direction toward the opening side, or the groove depth. Since the chips extend in the direction, the chips easily hit the second side wall portion 8 and are easily divided, and the chips are prevented from extending for a long time. Therefore, the chip disposal property is improved.

Further, in the present embodiment, since the angle α at which the second side wall portion 8 is inclined with respect to the groove depth direction is 10 ° or less, the chips are divided by the second side wall portion 8 and move to the outside of the groove portion 4. Chips can be stably discharged, and clogging of chips in the groove 4 can be suppressed.

Further, in the present embodiment, since the convex portion 13 has the convex curved surface-shaped first convex curved surface portion 13a connected to the land portion 5, the portion of the first convex curved surface portion 13a where the chips are scraped is easily dispersed, and the convex portion In 13, the concentration of force on a predetermined place is suppressed. Therefore, the strength of the cutting edge of the cutting edge 12 can be increased more stably.

Further, in the present embodiment, the radius of curvature of the first convex curved surface portion 13a is 0.05 mm or more and 0.2 mm or less in a cross-sectional view intersecting the cutting edge 3.
When the radius of curvature of the first convex curved surface portion 13a is 0.05 mm or more, the portion of the first convex curved surface portion 13a and the portion of the first side wall portion 7 connected to the first convex curved surface portion 13a (in the present embodiment, the inclined surface portion 14). ) Can be prevented from becoming too sharp, and chipping of the cutting edge can be suppressed.
Further, when the radius of curvature of the first convex curved surface portion 13a is 0.2 mm or less, chips can be stably curled by the convex curved surface of the first convex curved surface portion 13a while improving the fracture resistance of the cutting edge.

Further, in the present embodiment, the length (land width) L of the land portion 5 in the groove width direction is 0.05 mm or more and 0.2 mm or less.
When the length L of the land portion 5 in the groove width direction is 0.05 mm or more, the strength of the cutting edge can be ensured, so that the cutting edge defect can be suppressed.
When the length L of the land portion 5 in the groove width direction is 0.2 mm or less, the area (region) where the chips come into contact with the land portion 5 is suppressed to a small size, the cutting resistance is reduced, and the machining is stabilized.

Further, in the present embodiment, the length D in the groove depth direction between the end portion on the side of the first side wall portion 7 to the second side wall portion 8 in the groove width direction and the bottom portion 6 of the land portion 5 is 0. It is 1 mm or more and 0.3 mm or less.
When the length D in the groove depth direction between the land portion 5 and the bottom portion 6 is 0.1 mm or more, the chips are stably curled when entering the groove portion 4 and hit the second side wall portion 8. It is stable and divided.
When the length D in the groove depth direction between the land portion 5 and the bottom portion 6 is 0.3 mm or less, the chips that have entered the groove portion 4 are suppressed from staying in the groove portion 4, and the chips are clogged. It is suppressed. As a result, the cutting edge defect can be suppressed.

Further, in the present embodiment, the length W of the bottom portion 6 in the groove width direction is 0.1 mm or more and 0.3 mm or less.
When the length W of the bottom portion 6 in the groove width direction is 0.1 mm or more, the chips that have entered the groove portion 4 stably hit the second side wall portion 8, and the chips are more easily divided.
When the length W of the bottom portion 6 in the groove width direction is 0.3 mm or less, the accumulation of chips in the groove portion 4 is suppressed, and the tool is suppressed from being chipped.

Here, FIG. 5 shows a modified example of the blade portion 12 of the cutting tool 10 of the present embodiment, and shows a cross-sectional view intersecting the cutting edge 3.
In this modification, the land portion 5 is directed from the first side wall portion 7 in the groove width direction to the second side wall portion 8 side (inside the insert in the groove width direction), and from the opening in the groove depth direction to the bottom portion 6 side ( It extends incline toward the lower side in the groove depth direction). Further, the angle β at which the land portion 5 is inclined with respect to the reference plane RP perpendicular to the groove depth direction is 30 ° or less.

According to this modification, the land portion 5 extends inclined from the opening in the groove depth direction toward the bottom 6 side as the distance from the cutting edge 3 in the groove width direction increases, so that the rake angle of the cutting edge 3 is positive. It is made into a horn and the sharpness is enhanced. Therefore, the machined surface of the work material can be finished with good surface roughness with high accuracy.
Since the angle β at which the land portion 5 is tilted with respect to the reference plane RP perpendicular to the groove depth direction is 30 ° or less, the blade portion 12 is prevented from becoming too small in the blade angle of the cutting edge 3. The strength of the cutting edge of the blade can be stably increased.

<Second Embodiment>
Next, the cutting tool 20 according to the second embodiment of the present invention will be described with reference to FIGS. 6 to 8. In the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.
As shown in FIGS. 6 to 8, the cutting tool 20 of the present embodiment has a different structure of the convex portion 13 of the first side wall portion 7 from the cutting tool 10 described in the above-described embodiment.

In FIGS. 7 and 8, the convex portion 13 has a first convex curved surface portion 13a, a second convex curved surface portion 13b, and a connecting surface portion 13c.
The first convex curved surface portion 13a is located at the end portion on the outer side of the insert in the groove width direction (the upper end portion in the groove depth direction) in the convex portion 13. In the present embodiment, the end inside the insert in the groove width direction of the first convex curved surface portion 13a (lower end in the groove depth direction) is the end outside the insert in the groove width direction of the connecting surface portion 13c (groove). Connect with the upper end in the depth direction).

The second convex curved surface portion 13b is arranged between the first convex curved surface portion 13a and the bottom portion 6 to form a convex curved surface shape. In the present embodiment, the second convex curved surface portion 13b is arranged between the connecting surface portion 13c and the inclined surface portion 14. The second convex curved surface portion 13b is located at the end inside the insert in the groove width direction (lower end in the groove depth direction) in the convex portion 13. The outer end of the insert in the groove width direction of the second convex curved surface portion 13b (upper end in the groove depth direction) is the inner end of the insert in the groove width direction of the connection surface portion 13c (lower side in the groove depth direction). Connect with). The end inside the insert in the groove width direction of the second convex curved surface portion 13b (lower end in the groove depth direction) is the upper end in the groove depth direction of the inclined surface portion 14 (outside the insert in the groove width direction). Connect with).

As shown in FIG. 8, in the cross-sectional view intersecting the cutting edge 3, the second convex curved surface portion 13b has a convex curve shape. In the cross-sectional view shown in FIG. 8, the radius of curvature of the second convex curved surface portion 13b is, for example, 0.05 mm or more and 0.2 mm or less. In the present embodiment, in the cross-sectional view shown in FIG. 8, the width dimension of the second convex curved surface portion 13b is larger than the width dimension of the first convex curved surface portion 13a.

The connecting surface portion 13c is arranged between the first convex curved surface portion 13a and the second convex curved surface portion 13b. The connection surface portion 13c is located between both ends in the groove width direction (between both ends in the groove depth direction) in the convex portion 13. The connecting surface portion 13c has a linear shape in a cross-sectional view intersecting the cutting edge 3 shown in FIG. The connection surface portion 13c is inclined and extends downward in the groove depth direction toward the inside of the insert in the groove width direction. As shown in FIG. 7, of the connecting surface portion 13c, the portion 13c1 located inside the insert in the groove width direction of the corner blade portion 3a has a concave curved surface shape (concave tapered surface shape). Of the connection surface portion 13c, the portion 13c2 located inside the insert of the straight blade portion 3b in the groove width direction is flat.

[Action and effect according to this embodiment]
According to the cutting tool 20 of the present embodiment described above, the same action and effect as those of the above-described embodiment can be obtained.

Further, in the present embodiment, the convex portion 13 has a second convex curved surface portion 13b.
In this case, the portion where the chips are scraped is easily dispersed in the second convex curved surface portion 13b, and the concentration of the force in the predetermined portion in the convex portion 13 is suppressed. Therefore, the strength of the cutting edge of the cutting edge 12 can be increased more stably.
Further, by variously combining the shapes and sizes (for example, curvature and width dimension) of the first convex curved surface portion 13a and the second convex curved surface portion 13b, the degree of freedom of the shape (breaker shape) of the convex portion 13 can be increased. Increase.

Further, in the present embodiment, the convex portion 13 has a connecting surface portion 13c arranged between the first convex curved surface portion 13a and the second convex curved surface portion 13b.
In this case, the shape of the convex portion 13 can be freely combined by variously combining the shapes and sizes of the first convex curved surface portion 13a and the second convex curved surface portion 13b with the inclination angle and size of the connecting surface portion 13c. The degree is higher.

The groove portion 4 may have a side wall portion other than the first side wall portion 7 and the second side wall portion 8.
9 and 10 show a modified example of the second embodiment. In this modification, the groove portion 4 has a third side wall portion 16 in addition to the first side wall portion 7 and the second side wall portion 8. The third side wall portion 16 is arranged adjacent to the second side wall portion 8 in the direction in which the cutting edge 3 extends. The third side wall portion 16 is arranged so as to face the portion of the first side wall portion 7 that does not face the second side wall portion 8 in the groove width direction at a distance in the groove width direction. The third side wall portion 16 is arranged inside the insert in the groove width direction, for example, in a portion of the cutting edge 3 other than the portion used for cutting.

In the illustrated example, the third side wall portion 16 is arranged inside the insert in the groove width direction of the portion of the straight blade portion 3b located on the side opposite to the corner blade portion 3a along the blade length direction of the straight blade portion 3b. Will be done. The third side wall portion 16 extends inclinely toward the inside of the insert in the groove width direction from the bottom portion 6 in the groove depth direction toward the opening side of the groove portion 4. The distance between the third side wall portion 16 and the first side wall portion 7 in the groove width direction becomes smaller toward the direction opposite to the corner blade portion 3a along the blade length direction of the straight blade portion 3b.

[Other configurations included in the present invention]
The present invention is not limited to the above-described embodiment, and the configuration can be changed without departing from the spirit of the present invention, for example, as described below.

Although not particularly shown, the convex portion 13 may be formed in a convex shape by combining a plurality of inclined surfaces having different inclinations with respect to the reference surface RP. The plurality of inclined surfaces form a straight line in a cross-sectional view intersecting (orthogonal) with the cutting edge 3. In this case, the degree of freedom in the shape of the convex portion 13 is increased.

In the above-described embodiment, an example in which the cutting tools 10 and 20 are cutting inserts has been given, but the present invention is not limited to this. The cutting tool of the present invention may be, for example, a cutting tool (turning tool) in which the blade portion 12 is fixed to the tip portion.

In addition, each configuration (component) described in the above-described embodiments, modifications, and notes may be combined as long as it does not deviate from the gist of the present invention, and addition, omission, replacement, and other configurations may be added. It can be changed. Further, the present invention is not limited by the above-described embodiments, but is limited only by the scope of claims.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to this embodiment.

[Tool life confirmation test]
As Examples 1 to 9 and 12 to 17 of the present invention, the cutting tool 10 of the first embodiment was used. Further, as Examples 10 and 11 of the present invention, the cutting tool 20 of the second embodiment was used. Further, as a comparative example, a cutting tool in which a concave portion having a concave curved shape in a cross-sectional view intersecting the cutting edge 3 was prepared between the land portion 5 and the bottom portion 6. As an example of this recess, the shape shown in FIG. 4 of International Publication No. 2016/035490 was used. Then, the work material was machined under the following cutting conditions, and a tool life confirmation test was conducted.

<Cutting conditions>
-Machine tool: Lathe-Work material: Chrome steel (SCr420) Round bar-Work material dimensions: Diameter 50 mm, axial length 200 mm
・ Cutting speed: vc = 200m / min
・ Feed: fr = 0.2mm / rev
・ Cut: ap = 0.8mm
・ By dry cutting

The results of this test are shown in Table 1.
The items shown in Table 1 are as follows.
Land width L: Length L of the land portion 5 in the groove width direction
1st convex curved surface portion R ... Radius of curvature of the first convex curved surface portion 13a in the cross-sectional view intersecting the cutting edge 3 (for a comparative example, the radius of curvature of the concave portion in the cross-sectional view intersecting the cutting edge 3)
-Connecting surface width ... Length of the connecting surface 13c in the groove width direction-Second convex curved surface R ... Radius of curvature of the second convex curved surface 13b in a cross-sectional view intersecting the cutting edge 3-Groove depth D ... Land portion 5 The length D in the groove depth direction between the end portion on the side of the first side wall portion 7 to the second side wall portion 8 and the bottom portion 6 in the groove width direction.
・ Bottom width W: Length W of the bottom 6 in the groove width direction
-Angle α: An angle α at which the second side wall portion 8 is inclined with respect to the groove depth direction.
(When the angle α is “−”, the second side wall portion 8 is from the first side wall portion 7 to the second side wall portion in the groove width direction from the bottom portion 6 in the groove depth direction toward the opening side of the groove portion 4. (Indicates that it extends incline toward the 8 side)
・ Tool life: Cutting distance from the start of cutting to the loss of the cutting edge

As shown in Table 1, it was confirmed that in Examples 1 to 17 of the present invention, the tool life was all 3 km or more, and the fracture resistance of the cutting edge was higher than that of the comparative example. Among them, it was found that the tool life of Examples 1 to 11 was 4.7 km or more, and the fracture resistance was particularly excellent.

According to the cutting tool of the present invention, the strength of the cutting edge of the cutting edge can be increased and the chip controllability can be improved. Therefore, it has industrial applicability.

1 ... Scoop surface 2 ... Escape surface 3 ... Cutting edge 4 ... Groove 5 ... Land part 6 ... Bottom 7 ... 1st side wall part 8 ... 2nd side wall part 10, 20 ... Cutting tool 12 ... Blade part 13 ... Convex part 13a ... 1st convex curved surface portion 13b ... 2nd convex curved surface portion 13c ... Connection surface portion D ... Groove depth direction between the end portion on the groove width direction from the first side wall portion to the second side wall portion side and the bottom portion of the land portion. Length (groove depth)
L ... Length of the land portion in the groove width direction (land width)
RP: Reference surface W: Length of the bottom in the groove width direction (bottom width)
α: Angle at which the second side wall is inclined with respect to the groove depth direction β: Angle at which the land portion is inclined with respect to a reference plane perpendicular to the groove depth direction

Claims (11)

A cutting tool having a blade made of a cBN sintered body or a diamond sintered body.
The blade is
The rake face and
The escape surface and
It has a cutting edge formed at the intersecting ridgeline of the rake face and the flank surface.
The rake face is
A groove extending along the cutting edge and
It has a cutting edge and a land portion extending along the groove portion, which is arranged between the cutting edge and the groove portion.
The groove is
At the bottom
The openings of the groove from the bottom of the groove depth direction orthogonal to the groove width direction from both ends of the bottom in the groove width direction are arranged so as to face each other in the groove width direction of the groove. It has a first side wall portion and a second side wall portion extending to the side, and has.
The first side wall portion is located between the bottom portion and the land portion in the groove width direction.
The first side wall portion has a convex portion that intersects the cutting edge and has a convex shape in a cross-sectional view.
The convex portion faces from the first side wall portion in the groove width direction to the second side wall portion side and from the bottom portion in the groove depth direction to the opening side.
The second side wall portion is inclined and extends from the second side wall portion in the groove width direction toward the first side wall portion side as it is directed from the bottom portion in the groove depth direction toward the opening side. Extending along the groove depth direction,
Cutting tools. The angle at which the second side wall portion is inclined with respect to the groove depth direction is 10 ° or less.
The cutting tool according to claim 1. The convex portion has a convex curved first convex curved surface portion connected to the land portion.
The cutting tool according to claim 1 or 2. The radius of curvature of the first convex curved surface portion is 0.05 mm or more and 0.2 mm or less in a cross-sectional view intersecting the cutting edge.
The cutting tool according to claim 3. The convex portion has a convex curved second convex curved surface portion arranged between the first convex curved surface portion and the bottom portion.
The cutting tool according to claim 3 or 4. The convex portion is arranged between the first convex curved surface portion and the second convex curved surface portion, and has a connecting surface portion that intersects the cutting edge and forms a linear shape in a cross-sectional view.
The cutting tool according to claim 5. The convex portion is formed in a convex shape by combining a plurality of inclined surfaces having different inclinations with respect to a reference surface perpendicular to the groove depth direction.
The plurality of inclined surfaces form a straight line in a cross-sectional view intersecting the cutting edge.
The cutting tool according to claim 1 or 2. The land portion extends from the opening in the groove depth direction toward the bottom side inward from the first side wall portion in the groove width direction toward the second side wall portion side.
The angle at which the land portion is inclined with respect to the reference plane perpendicular to the groove depth direction is 30 ° or less.
The cutting tool according to any one of claims 1 to 7. The length of the land portion in the groove width direction is 0.05 mm or more and 0.2 mm or less.
The cutting tool according to any one of claims 1 to 8. The length in the groove depth direction between the end portion on the side of the second side wall portion from the first side wall portion in the groove width direction and the bottom portion of the land portion is 0.1 mm or more and 0.3 mm. Is below,
The cutting tool according to any one of claims 1 to 9. The length of the bottom portion in the groove width direction is 0.1 mm or more and 0.3 mm or less.
The cutting tool according to any one of claims 1 to 10.

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