| 摘要 |
<p>A drill bit (11) comprising a body (13) adapted to be supported from a hammer assembly and having an outer portion (15) which provides the cutting face (17) of the drill bit said outer portion having an integral central portion (19) having an outer axial end face (23) and a cylindrical side face, the outer portion further comprising an annular portion (21) which is removably receivable over a central portion, a locking means (37) adapted to retain the annular portion in position on the central portion at which position the end face of the central portion and the outer face of the annular portion co-operate to provide the cutting face.</p> |
