| 摘要 |
A drill for drilling in metal with improved performance in the smaller diameter range. The drill comprises a drill shaft, the front end of which is provided with radially outer and radially inner inserts, each insert having elongated rhomboidic shape, in which each of the short sides is broken at its middle to form a V-shape having an internal obtuse angle. The inserts are arranged such that the longitudinal axis of the radially outer insert is inclined at an angle from the longitudinal axis that is different from the angle of inclination between the longitudinal axis of the radially inner insert and the longitudinal axis of the drill. |
