| 摘要 |
<p>A rotary drill bit comprising a cutter bit (10) having a plurality of mutually displaced rows (12-17) of cutting means (11) extending in the circumferential direction of the cutter bit (10). The included cone angle (?) of the cutter bit (10) is larger than 90.degree. and adapted to the mutual positioning of the cutting means (11) on the cutter bit (10) in such a way that it is ensured that repetition of the pattern of the cutting means is avoided.</p> |
