| 摘要 |
<p>A twist drill (10, 110) having a longitudinal axis (18, 118), a shank portion sized and shaped to be grasped by a twisting tool, and a barrel portion (12, 112) for cutting a workpiece. The barrel portion (12, 112) has a number of flutes (14, 114) formed therein spiraling about the axis (18, 118) and terminating at a point end (16, 116) of the barrel portion (12, 112). The point end (16, 116) has a number of point surfaces (20, 120) including an inner flank surface (22, 122), an outer flank surface (26, 126), a groove surface (24, 124) positioned between the inner (22, 122) and outer (26, 126) flank surfaces and a split surface (28, 128). The inner flank surface (22, 122) extends from the center (40, 140) of the point end (16, 116) to the inner extent (23, 123) of the groove surface (24, 124) and the outer flank surface (26, 126) extends from the outer diameter (17, 117) of the point end (16, 116) to the outer extent (25, 125) of the groove surface (24, 124).</p> |
