| 摘要 |
The invention relates to a drill bit intended for percussive rock drillingof the type that comprises a front head (5) and a tubular skirt (6), whichextends rearward from the head to a rear, ring-shaped end and includesan internalthread(17) for the transfer ofcombined impact and rotary motions to the drill bit. Therear endof the skirt(6) is, viaan unelastic joint (24), e.g., a friction weld, united to a front end of a sleeve(4) havingan envelope surface, from which a plurality of projections (29) being peripherically spaced-apartfrom each other project, e.g., ridges, having the purpose of guiding the drill bit inthe drill hole. By assemblingthe drill bit oftwo parts, the internal thread(17) can be turned with high accuracy and smoothness, at the same time as the drill bit is givenan inherent good controllability. In anadditional aspect,the invention also relates to a method for the manufacture of such a drill bit. |
