| 摘要 |
A twist drill having a longitudinal axis, a shank portion sized and shaped to be grasped by a twisting tool, and a barrel portion for cutting a workpiece. The barrel portion has a number of flutes formed therein spiraling about the axis and terminating at a point end of the barrel portion. The point end has a number of point surfaces including an inner flank surface, an outer flank surface, a groove surface positioned between the inner and outer flank surfaces and a split surface. The inner flank surface extends from the center of the point end to the inner extent of the groove surface and the outer flank surface extends from the outer diameter of the point end to the outer extent of the groove surface. |
