Insert for drill, drill and method of cutting work material
An insert for a drill, a drill using the insert for a drill, and a method of cutting a work material are provided. The insert has an insert main body provided with a top surface and a side surface, a first cutting edge being formed on one side of an intersection part between the top surface and the side surface, a second cutting edge being formed on the other side of the intersection part between the top surface and the side surface, and being intersected with a virtual extension of the first cutting edge or the first cutting edge so as to have an outward convexity when viewed from above, a first breaking groove being formed in a concave shape along the first cutting edge in the top surface and having a maximum groove width at an end portion of the first cutting edge adjacent to the second cutting edge, and a second breaking groove being formed in a concave shape along the second cutting edge in the top surface and having a maximum groove width at an end portion of the second cutting edge adjacent to the first cutting edge.
1. An insert for a drill, comprising:
an insert main body with a top surface and a side surface;
wherein the insert main body comprises
a cutting edge on an intersection part of the top surface and the side surface which comprises a bent portion projected outward when viewed from the top surface, and
a breaking groove on the top surface which comprises a concave shape along the cutting edge,
wherein a width of the breaking groove is a maximum at a position corresponding to the bent portion,
wherein the breaking groove comprises a rise face part inclined higher as a distance from the cutting edge increases, and
wherein the rise face part comprises a minimum rise angle at the position corresponding to the bent portion.
2. The insert for a drill according to claim 1 , wherein the width of the breaking groove becomes larger from a position corresponding to an one end of the cutting edge to the position corresponding to the bent portion.
3. The insert for a drill according to claim 2 , wherein the width of the breaking groove becomes larger from a position corresponding to the other end of the cutting edge to the position corresponding to the bent portion.
4. The insert for a drill according to claim 1 , wherein the insert main body further comprises a land along the cutting edge at a position between the breaking groove and the cutting edge, and
wherein a width of the land is maximum at the position corresponding to the bent portion.
5. The insert for a drill according to claim 4 , wherein the width of the land becomes larger from a position corresponding to an one end of the cutting edge to the position corresponding to the bent portion.
6. The insert for a drill according to claim 5 , wherein the width of the land becomes larger from a position corresponding to the other end of the cutting edge to the position corresponding to the bent portion.
7. The insert for a drill according to claim 1 , wherein the insert main body further comprises
another cutting edge on at least a part of an intersection part of the top surface and other side surface different from the side surface; and
another breaking groove which comprises a concave shape along the other cutting edge,
wherein a width of the other breaking groove becomes larger from a position corresponding to an one end of the cutting edge to a position corresponding to the other end of the cutting edge.
8. An insert for a drill, comprising:
an insert main body with a top surface and a side surface;
wherein the insert main body comprises
a cutting edge on an intersection part of the top surface and the side surface which comprises a bent portion projected outward when viewed from the top surface, and
a breaking groove on the top surface which comprises a concave shape along the cutting edge,
wherein a width of the breaking groove is a maximum at a position corresponding to the bent portion,
wherein the breaking groove comprises a rake face part inclined higher as a distance from the cutting edge decreases, and
wherein the rake face part comprises a minimum rake angle at the position corresponding to the bent portion.
9. The insert for a drill according to claim 8 , wherein the width of the breaking groove becomes larger from a position corresponding to an one end of the cutting edge to the position corresponding to the bent portion.
10. The insert for a drill according to claim 9 , wherein the width of the breaking groove becomes larger from a position corresponding to the other end of the cutting edge to the position corresponding to the bent portion.
11. The insert for a drill according to claim 8 , wherein the insert main body further comprises a land along the cutting edge at a position between the breaking groove and the cutting edge, and
wherein a width of the land is maximum at the position corresponding to the bent portion.
12. The insert for a drill according to claim 11 , wherein the width of the land becomes larger from a position corresponding to an one end of the cutting edge to the position corresponding to the bent portion.
13. The insert for a drill according to claim 12 , wherein the width of the land becomes larger from a position corresponding to the other end of the cutting edge to the position corresponding to the bent portion.
14. The insert for a drill according to claim 8 , wherein the insert main body further comprises
another cutting edge on at least a part of an intersection part of the top surface and other side surface different from the side surface; and
another breaking groove which comprises a concave shape along the other cutting edge,
wherein a width of the other breaking groove becomes larger from a position corresponding to an one end of the cutting edge to a position corresponding to the other end of the cutting edge.