Cutting insert, cutting tool, and method of manufacturing machined product using the same

1. A cutting insert, comprising:

an upper surface;

a side surface; and

a cutting edge located at an intersection region of the upper surface and the side surface,

wherein

the upper surface comprises

a rake surface continuous with the cutting edge, and

a rising surface inclined and lying at a higher position as going inward from the rake surface, and

the rake surface comprises

a pair of first raised parts respectively extending inward from near both ends of the cutting edge in a top view, and

a second raised part extending from one of the pair of first raised parts to the other.

2. The cutting insert according to claim 1 , wherein a ridge portion of the second raised part is parallel to the cutting edge in a top view.

3. The cutting insert according to claim 1 , wherein the second raised part comprises

a first inclined surface inclined at an inclination angle α 1 and lying at a higher position as going from the cutting edge to the ridge portion of the second raised part, and

a second inclined surface inclined at an inclination angle α 2 and lying at a lower position as going from the ridge portion of the second raised part to the rising surface.

4. The cutting insert according to claim 3 , wherein the inclination angle α 1 of the first inclined surface is larger than the inclination angle α 2 of the second inclined surface.

5. The cutting insert according to claim 4 , wherein a rising angle γ of the rising surface is larger than the inclination angle α 1 of the first inclined surface.

6. The cutting insert according to claim 1 , wherein the ridge portion of the second raised part is located below a virtual straight line connecting respective ridge portions of the pair of first raised parts in a side view.

7. The cutting insert according to claim 1 ,

wherein both W 1 and W 2 in each of the pair of first raised parts are smaller at a side of the second raised part than a side of the cutting edge, where

W 1 is a distance between the ridge portion of one of the first raised parts and the other ridge portion, and

W 2 is a distance between an intersection region of the one first raised part and a bottom part of the rake surface, and an intersection region of the other first raised part and the bottom part of the rake surface.

8. The cutting insert according to claim 7 , wherein both the W 1 and the W 2 decrease as going from the cutting edge to the second raised part.

9. The cutting insert according to claim 7 , wherein both the W 1 and W 2 are larger a side of the rising surface than the side of the second raised part.

10. The cutting insert according to claim 7 , wherein both the W 1 and the W 2 increase as going from the second raised part to the rising surface.

11. The cutting insert according to claim 1 , wherein

the cutting edge comprises a first cutting edge and a second cutting edge intersecting each other, and

at least one of the pair of first raised parts. comprises an approach portion, wherein the approach portion extends along the second cutting edge and approaches the second cutting edge as separating from the first cutting edge.

12. The cutting insert according to claim 11 , wherein the approach portion comprises an end portion of the at least one of the plurality of the first raised parts, the end portion being further away from the first cutting edge.

13. The cutting insert according to claim 11 , wherein the at least one first raised part comprises an inclined portion inclined and lying at a higher position as going from the second cutting edge to the ridge portion of the at least one of the plurality of the first raised parts.

14. The cutting insert according to claim 13 , wherein the approach portion further comprises an end portion of the inclined portion, the end portion being further away from the first cutting edge.

15. The cutting insert according to claim 13 , wherein the approach portion further comprises a lower end of the inclined portion, the lower end being closer to the second cutting edge.

16. The cutting insert according to claim 11 , wherein the approach portion includes the ridge portion of the at least one of the plurality of the first raised parts.

17. The cutting insert according to claim 11 , wherein the at least one of the plurality of the first raised parts is inclined and lying at a lower position as going to the end portion further away from the first cutting edge in a side view.

18. The cutting insert according to claim 11 , wherein a pair of the second cutting edges are respectively disposed on both sides of the first cutting edge.

19. The cutting insert according to claim 18 , wherein the pair of first raised parts are disposed symmetrical to each other along the pair of second cutting edges in a top view.

20. The cutting insert according to claim 1 , wherein the upper surface further comprises a clamp surface positioned inward compared to the rising surface.

21. A cutting tool, comprising:

a cutting insert according to claim 1 ; and

a holder configured to attach the cutting insert to a front end thereof.

22. A method of manufacturing a machined product, comprising:

rotating a workpiece;

bringing the workpiece being rotated and the cutting edge of the cutting tool according to claim 21 into contact with each other; and

separating the workpiece and the cutting tool from each other.