Cutting insert, cutting tool, and method for manufacturing machined product
A cutting insert may include an upper surface, a lower surface, a lateral surface and a cutting edge. The upper surface may include a first corner, a first side, a second side and a rake surface. The cutting edge may include a first cutting edge located on the first corner, and a second cutting edge located on the first side. The first cutting edge may include a first part. The first part may be located between a midportion of the first corner and the first side, and may come closer to a reference plane as going away from the first side. The rake surface may include a first region located along the first part. A rake angle in the first region may become smaller as coming closer to the midportion of the first corner.
1. A cutting insert, comprising:
an upper surface comprising
a first corner having a convex curvilinear shape, and
a first side and a second side each connecting to the first corner;
a lower surface located on a side opposite to the upper surface;
a lateral surface located between the upper surface and the lower surface; and
a cutting edge located on an intersection of the upper surface and the lateral surface, wherein
an imaginary straight line passing through a center of the upper surface and a center of the lower surface is a central axis,
an imaginary plane, which is located between the upper surface and the lower surface and is orthogonal to the central axis, is a reference plane,
the cutting edge comprises
a first cutting edge located on the first corner, and
a second cutting edge located on the first side,
the first cutting edge comprises
a first part which is located between a midportion of the first corner and the first side, and which comes closer to the reference plane as going away from the first side, and
a third part located so as to include the midportion of the first corner,
the upper surface further comprises a rake surface located along the cutting edge,
the rake surface comprises
a first region located along the first part, and
a third region located along the third part,
a rake angle in the first region becomes smaller as coming closer to the midportion of the first corner, and
a rake angle in the third region is smaller than the rake angle in the first region.
2. The cutting insert according to claim 1 , wherein
the first cutting edge further comprises a second part which is located between the first part and the first side, and which is located more away from the reference plane as going away from the first side,
the rake surface further comprises a second region located along the second part, and
a rake angle in the second region becomes larger as coming closer to the first part.
3. The cutting insert according to claim 1 , wherein
the third region is flat.
4. The cutting insert according to claim 1 , wherein
the first cutting edge further comprises a fourth part which is located between the midportion of the first corner and the second side, and which comes closer to the reference plane as going away from the second side,
the rake surface further comprises a fourth region located along the fourth part, and
a rake angle in the fourth region becomes smaller as coming closer to the midportion of the first corner.
5. The cutting insert according to claim 4 , wherein
the first cutting edge further comprises a fifth part which is located between the fourth part and the second side, and which is located more away from the reference plane as going away from the second side,
the rake surface further comprises a fifth region located along the fifth part, and
a rake angle in the fifth region becomes larger as coming closer to the fourth part.
6. The cutting insert according to claim 1 , wherein
the first region is flat.
7. The cutting insert according to claim 6 , wherein
the rake surface further comprises a sixth region that is flat and located along the second cutting edge, and
the first region and the sixth region are located on one flat surface.
8. A cutting tool, comprising:
a holder having a bar shape extended from a first end toward a second end, the holder comprising a pocket located at the first end; and
the cutting insert according to claim 1 , the cutting insert being located in the pocket.
9. A method for manufacturing a machined product, comprising:
rotating a workpiece;
bringing the cutting tool according to claim 8 into contact with the workpiece being rotated; and
moving the cutting tool away from the workpiece.
10. A cutting insert, comprising:
an upper surface comprising
a first corner having a convex curvilinear shape, and
a first side and a second side each connecting to the first corner;
a lower surface located on a side opposite to the upper surface;
a lateral surface located between the upper surface and the lower surface; and
a cutting edge located on an intersection of the upper surface and the lateral surface, wherein
an imaginary straight line passing through a center of the upper surface and a center of the lower surface is a central axis,
an imaginary plane, which is located between the upper surface and the lower surface and is orthogonal to the central axis, is a reference plane,
the cutting edge comprises
a first cutting edge located on the first corner, and
a second cutting edge located on the first side,
the first cutting edge comprises
a first part which is located between a midportion of the first corner and the first side, and which comes closer to the reference plane as going away from the first side,
a fourth part which is located between the midportion of the first corner and the second side, and which comes closer to the reference plane as going away from the second side, and
a fifth part which is located between the fourth part and the second side, and which is located more away from the reference plane as going away from the second side,
the upper surface further comprises a rake surface located along the cutting edge,
the rake surface comprises
a first region located along the first part,
a fourth region located along the fourth part, and
a fifth region located along the fifth part,
a rake angle in the first region becomes smaller as coming closer to the midportion of the first corner,
a rake angle in the fourth region becomes smaller as coming closer to the midportion of the first corner, and
a rake angle in the fifth region becomes larger as coming closer to the fourth part.
11. The cutting insert according to claim 10 , wherein
the first cutting edge further comprises a second part which is located between the first part and the first side, and which is located more away from the reference plane as going away from the first side,
the rake surface further comprises a second region located along the second part, and
a rake angle in the second region becomes larger as coming closer to the first part.
12. The cutting insert according to claim 10 , wherein
the first cutting edge further comprises a third part located so as to include the midportion of the first corner,
the rake surface further comprises a third region located along the third part, and
a rake angle in the third region is smaller than the rake angle in the first region.
13. The cutting insert according to claim 10 , wherein
the first region is flat.
14. The cutting insert according to claim 13 , wherein
the rake surface further comprises a sixth region that is flat and located along the second cutting edge, and
the first region and the sixth region are located on one flat surface.
15. A cutting insert, comprising:
an upper surface comprising
a first corner having a convex curvilinear shape, and
a first side and a second side each connecting to the first corner;
a lower surface located on a side opposite to the upper surface;
a lateral surface located between the upper surface and the lower surface; and
a cutting edge located on an intersection of the upper surface and the lateral surface, wherein
an imaginary straight line passing through a center of the upper surface and a center of the lower surface is a central axis,
an imaginary plane, which is located between the upper surface and the lower surface and is orthogonal to the central axis, is a reference plane,
the cutting edge comprises
a first cutting edge located on the first corner, and
a second cutting edge located on the first side,
the first cutting edge comprises a first part which is located between a midportion of the first corner and the first side, and which comes closer to the reference plane as going away from the first side,
the upper surface further comprises a rake surface located along the cutting edge,
the rake surface comprises a first region located along the first part, wherein the first region is flat, and
a rake angle in the first region becomes smaller as coming closer to the midportion of the first corner.
16. The cutting insert according to claim 15 , wherein
the first cutting edge further comprises a second part which is located between the first part and the first side, and which is located more away from the reference plane as going away from the first side,
the rake surface further comprises a second region located along the second part, and
a rake angle in the second region becomes larger as coming closer to the first part.
17. The cutting insert according to claim 15 , wherein
the first cutting edge further comprises a third part located so as to include the midportion of the first corner,
the rake surface further comprises a third region located along the third part, and
a rake angle in the third region is smaller than the rake angle in the first region.
18. The cutting insert according to claim 15 , wherein
the first cutting edge further comprises a fourth part which is located between the midportion of the first corner and the second side, and which comes closer to the reference plane as going away from the second side,
the rake surface further comprises a fourth region located along the fourth part, and
a rake angle in the fourth region becomes smaller as coming closer to the midportion of the first corner.
19. The cutting insert according to claim 18 , wherein
the first cutting edge further comprises a fifth part which is located between the fourth part and the second side, and which is located more away from the reference plane as going away from the second side,
the rake surface further comprises a fifth region located along the fifth part, and
a rake angle in the fifth region becomes larger as coming closer to the fourth part.