| 摘要 |
1. Drill comprising at least two cutting inserts (4, 5), which are removably fixed in housings provided at its end, the cutting edges of said inserts emerging in grooves (2, 3) provided in the body (1) of the drill and each of said cutting edges ensuring, during the revolution of the piece to be machined or of the drill, a part of the whole cutting surface thereof, and one of the inserts presenting a cutting edge with a circular shape (4), at least a point thereof being located on the longitudinal axis of the drill, characterized by the fact that at least one insert (5) presents a shape which is different from that of the other inserts. |
