| 摘要 |
A throw away insert (1) having straight cutting edges (2), arcuately curved corner portions (3) formed between the adjacent cutting edges, and a rake facing having a center land. In the rake face, chip breaker grooves (4) are formed near the corner portions. Each breaker groove adjoins the center land (5) along line inclined with respect to one of the adjacent cutting edges and is inclined with respect to the direction of thickness of the insert. An ellipsoidal recess (6) is formed in the bottom surface of each breaker groove at the boundary between the center land and the breaker groove. The ellipsoidal recesses have a major axis extending parallel to borderline between the center land and the breaker groove. |
