| 摘要 |
The invention concerns a drill bit, intended to be used with a down-the-hole drill and comprising a drill head (2) with a front surface provided with drill pins (3) and a shaft (4), whereby the shaft is narrower than the drill head and intended to be inserted in a manner that allows axial sliding into the end of a drill chuck that is a component of a down-the- hole drill and which shaft has a rear end part (6) that is somewhat thickened with a plane striking surface (7) against which a hammer piston (8) that is a component of the down- the-hole hammer drill is arranged to impact, that the drill head when viewed along its axial direction has a cylinder-shaped forward part (20) provided with cuttings channels (22), a rear cylinder-shaped part (21) that is located for the reception of drill cuttings at the same level or somewhat below the bottom (25) of the cuttings channels, whereby the diameter (D1) of the forward part is greater than the diameter (D2) of the rear part. In a drill bit that has high performance and a long useful life, and that is furthermore well-suited to be used for directed drilling, the cylinder-shaped forward part (20) of the drill head (2) has an axial length (L3) from the main plane of the front surface to a shoulder plane (26) located between the drill head (2) and the shaft (4) that is greater than the axial length (L4) of the cylinder-shaped rear part (21) of the drill head. |
