| 摘要 |
A rotary or rotary/percussion drill bit 10 has a taper socket 14 in one end. A wall 18 bounds the socket 14. A plurality of recesses 20 is provided in the wall. In one embodiment, each recess 20 extends longitudially and resembles a flute. It has a valley 22 flanked by peaks 24. In another embodiment, the recesses may be circumferential, e.g. helical.
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