High-feed cutting insert and cutting tool equipped with same

1. A high feed cutting insert comprising:

a main surface and a sub-surface facing each other in opposite directions; two short side surfaces connecting the main surface and the sub-surface and facing each other in opposite directions; two long side surfaces connecting the main surface and the sub-surface, connecting the two short side surfaces, facing each other in opposite directions, and having a greater width than that of the short side surfaces; and a fastening hole extending through the two long side surfaces, through which a cutting tool fastening bolt is inserted, wherein the high feed cutting insert comprises:

short cutting edges provided on boundary portions between the main surface and the short side surfaces;

long cutting edges provided on boundary portions between the main surface and the long side surfaces;

first two corner cutting edges connecting the short cutting edges and the long cutting edges, and each thereof placed diagonally to each other; and

second two corner cutting edges, each thereof placed diagonally to each other and having a lower height than the first two corner cutting edges,

wherein the short cutting edges and the long cutting edges,

when viewed towards the main surface,

form an obtuse angle while the first corner cutting edges are interposed therebetween and,

form an acute angle while the second corner cutting edges are interposed therebetween,

wherein, when viewed towards the long side surfaces, the long cutting edges include

concave sections that are inwardly concave; and

straight line section connecting the concave sections.

2. The high feed cutting insert according to claim 1 , wherein the short cutting edges have a curved, outwardly convex shape when viewed towards the main surface.

3. The high feed cutting insert according to claim 1 , wherein the short cutting edges have a downwardly-inclined shape from the first corner cutting edges to the second corner cutting edges, when viewed towards the short side surfaces.

4. The high feed cutting insert according to claim 3 , wherein the short cutting edges have a curved, outwardly convex shape when viewed towards the short side surfaces.

5. The high feed cutting insert according to claim 1 , wherein, when viewed towards the long side surfaces,

the concave sections start at the first corner cutting edges and end at the straight line sections, and

the straight sections start at the concave sections and end at the second corner cutting edges and have a downwardly-inclined shape towards the second corner cutting edges.

6. The high feed cutting insert according to claim 5 , wherein, when viewed towards the long side surfaces,

the first corner cutting edges have an outwardly convex shape, and

the second corner cutting edges have an inwardly concave shape.

7. The high feed cutting insert according to claim 1 , wherein the short side surfaces include

first clearance surfaces adjacent to the short cutting edges; and

second clearance surfaces connecting the first clearance surfaces and the sub-surface,

wherein the first clearance surfaces form a right angle with respect to the main surface, and

the second clearance surfaces form an obtuse angle with respect to the sub-surface and has a generally planar shape.

8. The high feed cutting insert according to claim 7 , wherein, when viewed from the short lateral surfaces,

a portion of the first clearance surfaces adjacent to the first corner cutting edges is connected to the sub-surface.

9. The high feed cutting insert according to claim 1 , wherein the sub-surface has a straight line shape when viewed towards each of the short side surfaces and the long side surfaces.

10. The high feed cutting insert according to claim 1 , wherein the main surface is rotationally symmetrical by 180 degrees with respect to a center thereof.

11. The high feed cutting insert according to claim 1 , wherein the main surface and the sub-surface have the same shape as each other,

each of the main surface and the sub-surface is rotationally symmetrical by 180 degrees with respect to a center thereof,

each of the short side surfaces is rotationally symmetrical by 180 degrees with respect to a center thereof, and

each of the long side surfaces is rotationally symmetrical by 180 degrees with respect to a center thereof.

12. The high feed cutting insert according to claim 1 , wherein

each of the main surface and the sub-surface is rotationally symmetrical by 180 degrees with respect to a center thereof,

each of the short side surfaces is laterally symmetrical with respect to a center line that runs across the long side surfaces, and

each of the long side surfaces is laterally symmetrical with respect to a center line that runs across the short side surfaces.

13. A cutting tool equipped with the high feed cutting insert according to claim 1 , comprising:

a first seat surface on which the sub-surface is placed;

a second seat surface on which the short side surfaces are placed; and

a third seat surface on which the long side surfaces are placed,

wherein the third seat surface is inclined in a direction further away from a center of the cutting tool towards a bottom of the cutting tool.