| 摘要 |
A rotary drill comprises a shank, two axially extending chip removal recesses, and at least two radially oriented cutting inserts. One insert is peripherally located and is arranged adjacent one of the chip removal recesses. The edge of the peripheral insert extends radially so as to form the wall of the hole to be drilled. Another insert is located radially inwardly of the peripheral insert and is arranged adjacent the other chip removal recess. The inserts extend axially to generally the same extent. The inner insert is offset from a 180 degree relationship with the peripheral insert by an angle, which angle is of such magnitude that the drill is radially balanced. |
