| 摘要 |
A cutting insert includes an insert body 1 having a polygonal plate shape. Rake faces 3 are formed on polygonal surfaces of the insert body 1, and flank faces 4 are formed on lateral faces of the insert body 1 arranged around the polygonal surfaces. Main cutting edges 5 are formed on side ridges of the polygonal surfaces at intersecting ridgelines between the rake faces 3 and the flank faces 4. Each main cutting edge 5 extends between two corners adjacent to each other in a circumferential direction of the polygonal surface among corners of the polygonal surface. When seen from a direction opposing the rake face 3, one end portion 5a of the main cutting edge 5 that stretches to one corner of the two corners has a convexly curved shape, and the other end portion 5b of the main cutting edge 5 that stretches to the other corner of the two corners has a concavely curved shape. |
