| 摘要 |
The present invention relates to a partially enhanced drill bit (10') for percussive drilling. The bit comprises a bit body, at least one annular row of non-enhanced buttons (11') mounted in the bit body; and at least one annular row of enhanced buttons (12') mounted in the bit body radially outside of the non-enhanced buttons. At least one annular row of non-enhanced buttons (11') and said at least one annular row of enhanced buttons (12') are provided to partly overlap each other. There is an axial shoulder (19') radially outside of the non-enhanced buttons (11'). There are chamfers (20') at least partly surrounding the enhanced buttons (12'). These chamfers (20') interrupt the shoulder (19') in the circumferential direction.
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