| 摘要 |
The present invention relates to a downhole-hammer drill-bit assembly for removable attachment to a substantially tubular casing of a downhole hammer. The drill-bit assembly has a substantially tubular chuck, a drill-bit, and a substantially tubular retainer. The chuck has a step. The drill-bit has a bit shank, a bit shoulder extending from the shank and a bit head. A 6first portion of the bit shank is in a bore of the chuck. The retainer has a split retainer sidewall, a first end and a second end. The first end has a split retainer collar. The second end has a split retainer ring. The split retainer sidewall is around a portion of the chuck and the bit shoulder. The split retainer collar is around a first surface of the step. The split retainer ring is around a portion of the bit shank between the bit shoulder and the bit head.
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