| 摘要 |
A drill bit for percussive rock drilling of the type that comprises a front head and a tubular skirt, which extends rearward from the head to a rear, ring-shaped end and includes an internal thread for the transfer of combined impact and rotary motions to the drill bit is disclosed. The rear end of the skirt is, via an unelastic joint, e.g., a friction weld, united to a front end of a sleeve having an envelope surface, from which a plurality of projections are peripherically spaced-apart from each other project, e.g., ridges, having the purpose of guiding the drill bit in the drill hole. By assembling the drill bit of two parts, the internal thread can be turned with high accuracy and smoothness, at the same time as the drill bit is given an inherent good controllability. In an additional aspect, a method for the manufacture of such a drill bit is also disclosed. |
