Cutting insert for grooving operations

1. A grooving insert comprising:

at least one cutting portion comprising a top surface and a peripheral side surface extending away from the top surface;

the top surface and peripheral side surface meeting at an upper edge, at least a portion of which comprises a cutting edge;

the cutting edge comprising a forward main cutting edge and two opposing side cutting edges extending rearwardly from the forward main cutting edge; wherein

each side cutting edge has a serrated form in a top view of the grooving insert.

2. The grooving insert according to claim 1 , wherein

each side cutting edge comprises a plurality of steps, each step comprising a forward section and a rear section;

the rear section of one step merging with the forward section of an adjacent step; and

no two of said forward sections lie on the same line, in a top view of the grooving insert.

3. The grooving insert according to claim 2 , wherein the peripheral side surface of the at least one cutting portion comprises one end surface and two opposing side surfaces extending rearwardly from the end surface, the end surface meeting the top surface at the forward main cutting edge and the two opposing side surfaces meeting the top surface at the two opposing side cutting edges, and

the shape of the side surface, at least adjacent the upper edge, is similar to the shape of the upper edge in a top view of the grooving insert.

4. The grooving insert according to claim 2 , wherein the steps of one side cutting edge are lined up with the steps of the other side cutting edge so that the upper edge has mirror symmetry about a plane passing through a center line of the grooving insert, with the steps of the two opposing side cutting edges forming pairs of opposing steps relative to the center line.

5. The grooving insert according to claim 4 , wherein a corner section is located between each forward and rear section of a given step, the corner sections of a first of the two opposing side cutting edges lie on a first line and the corner sections of the second of the two opposing side cutting edges lie on a second line.

6. The grooving insert according to claim 5 , wherein the first and second lines converge forwardly.

7. The grooving insert according to claim 4 , wherein the forward section of each step of a given pair of opposing steps, lies on a line of a pair of opposing lines that converge forwardly.

8. The grooving insert according to claim 7 , wherein the rear section of each step of a given pair of opposing steps lies on a line of a pair of opposing lines that converge rearwardly.

9. The grooving insert according to claim 1 , wherein the two opposing side cutting edges are identical.

10. The grooving insert according to claim 2 , wherein for each step the forward section is oriented at an acute angle to a direction of feed of the grooving insert and at obtuse angle to the rear section.

11. A grooving insert comprising:

at least one cutting portion comprising a top surface and a peripheral side surface extending away from the top surface;

the top surface and peripheral side surface meeting at an upper edge, at least a portion of which comprises a cutting edge;

the cutting edge comprising a forward main cutting edge and two opposing side cutting edges extending rearwardly from the forward main cutting edge; wherein

each side cutting edge comprises a plurality of steps, each step comprising a forward section and a rear section;

the forward section is oriented at a first acute angle to a direction of feed of the grooving insert and the rear section is relieved by a second acute angle from the direction of feed; and

the rear section of one step merges with the forward section of an adjacent step.

12. The grooving insert according to claim 11 , wherein the steps of one side cutting edge are lined up with the steps of the other side cutting edge so that the upper edge has mirror symmetry about a plane passing through a center line of the grooving insert, with the steps of the two opposing side cutting edges forming pairs of opposing steps relative to the center line.

13. The grooving insert according to claim 12 , wherein a corner section is located between each forward and rear section of a given step, the corner sections of a first of the two opposing side cutting edges lie on a first line and the corner sections of the second of the two opposing side cutting edges lie on a second line.

14. The grooving insert according to claim 13 , wherein the first and second lines converge forwardly to the forward sections of the first step on either side of the forward main cutting edge.

15. The grooving insert according to claim 14 , wherein each side cutting edge has a serrated form in a top view of the grooving insert.

16. A grooving insert comprising:

at least one cutting portion comprising a top surface and a peripheral side surface extending away from the top surface;

the top surface and peripheral side surface meeting at an upper edge, at least a portion of which comprises a cutting edge;

the cutting edge comprising a forward main cutting edge and two opposing side cutting edges extending rearwardly from the forward main cutting edge; wherein

each side cutting edge comprises a plurality of steps, each step comprising a forward section, a rear section and a corner section therebetween; and

the corner sections of a first of the two opposing side cutting edges lie on a first line and the corner sections of the second of the two opposing side cutting edges lie on a second line, the first and second lines converging forwardly to the forward sections of the first step on either side of the forward main cutting edge.

17. A grooving insert comprising:

at least one cutting portion comprising a top surface and a peripheral side surface extending away from the top surface;

the top surface and peripheral side surface meeting at an upper edge, at least a portion of which comprises a cutting edge;

the cutting edge comprising a forward main cutting edge and two opposing side cutting edges extending rearwardly from the forward main cutting edge;

each side cutting edge comprising a plurality of steps, each step comprising a forward section, a rear section and a corner section therebetween;

the steps of one side cutting edge are lined up with the steps of the other side cutting edge, with the steps of the two opposing side cutting edges forming pairs of opposing steps, wherein:

the forward section of each step of a given pair of opposing steps lies on a line of a pair of opposing lines that converge forwardly, and

the rear section of each step of a given pair of opposing steps lies on a line of a pair of opposing lines that converge rearwardly.

18. A grooving insert comprising:

at least one cutting portion comprising a top surface provided with a cutting edge, the cutting edge comprising a forward main cutting edge and two opposing side cutting edges extending rearwardly from the forward main cutting edge; wherein

each side cutting edge has a serrated form in a top view of the top surface.

19. The grooving insert according to claim 18 , wherein the cutting portion further comprises:

a peripheral side surface comprising one end surface and two opposing side surfaces extending rearwardly from the end surface, the end surface meeting the top surface at the forward main cutting edge and the two opposing side surfaces meeting the top surface at the two opposing side cutting edges, and

the shape of each side surface, at least adjacent the top surface, is similar to the shape of each associated side cutting edge in a top view of the top surface.

20. The grooving insert according to claim 18 , wherein:

each side cutting edge comprises a plurality of steps; and

the steps of one side cutting edge are lined up with the steps of the other side cutting edge so that the cutting edge has mirror symmetry about a plane passing through a center line of the grooving insert, with the steps of the two opposing side cutting edges forming pairs of opposing steps relative to the center line.

21. The grooving insert according to claim 18 , wherein:

each side cutting edge comprises a plurality of steps, each step comprising a forward section and a rear section;

the rear section of one step merges with the forward section of an adjacent step; and

the forward section is oriented at a first acute angle to a direction of feed of the grooving insert and the rear section is relieved by a second acute angle from the direction of feed.

22. The grooving insert according to claim 18 , wherein:

each side cutting edge comprises a plurality of steps, each step comprising a forward section and a rear section;

the rear section of one step merges with the forward section of an adjacent step; and

a corner section is located between each forward and rear section of a given step, the corner sections of a first of the two opposing side cutting edges lie on a first line and the corner sections of the second of the two opposing side cutting edges lie on a second line.

23. The grooving insert according to claim 22 , wherein the first and second lines converge forwardly.

24. The grooving insert according to claim 18 , wherein:

each side cutting edge comprises a plurality of steps, each step comprising a forward section and a rear section;

the rear section of one step merges with the forward section of an adjacent step; and

no two of said forward sections lie on the same line, in a top view of the top surface.

25. The grooving insert according to claim 24 , wherein the steps of one side cutting edge are lined up with the steps of the other side cutting edge so that the upper edge has mirror symmetry about a plane passing through a center line of the grooving insert, with the steps of the two opposing side cutting edges forming pairs of opposing steps relative to the center line.

26. The grooving insert according to claim 25 , wherein the forward section of each step of a given pair of opposing steps, lies on a line of a pair of opposing lines that converge forwardly.

27. The grooving insert according to claim 25 , wherein the rear section of each step of a given pair of opposing steps lies on a line of a pair of opposing lines that converge rearwardly.

28. The grooving insert according to claim 18 , wherein:

each side cutting edge comprises a plurality of steps, each step comprising a forward section and a rear section;

the rear section of one step merges with the forward section of an adjacent step; and

for each step, the forward section is oriented at an acute angle to a direction of feed of the grooving insert and at obtuse angle to the rear section.

29. A method of machining a piston to form a ring groove, the method comprising:

providing a cutting insert having a cutting edge comprising a forward main cutting edge and two opposing side cutting edges extending rearwardly from the forward main cutting edge, each side cutting edge having a serrated form in a top view of the top surface;

roughing a groove in the piston with said cutting insert; and

finishing the groove.