| 摘要 |
PCT No. PCT/SE96/01039 Sec. 371 Date May 6, 1998 Sec. 102(e) Date May 6, 1998 PCT Filed Aug. 22, 1996 PCT Pub. No. WO97/08421 PCT Pub. Date Mar. 6, 1997The present invention relates to a drilling tool for percussive drilling by means of a top hammer unit, which unit gives compressive pulses. The tool comprises at least one drill tube (12) and a drill bit (11), which cooperates via a connection. The drill bit comprises a bit head (13) provided with crushing means (15) and a shank (17). A shoulder (20) is provided in connection with the bit head, said bit portion having a first abutment surface (21) facing towards a free end of the tube. The free end of the tube facing towards the drill bit is povided with a second abutment surface (23), said top hammer unit being provided to tannsfer compressive pulses to the tube. Each compressive pulse is transferred to the drill bit via the impact surfaces (21, 23). The tube and the drill bit comprise cooperating device (19, 24, 25) for driving and retaining. The tool is defined by that it has a relation between the length of the shank and the length of the bit head that is 5 or more. The present invention futher relates to a method, an intermediate portion as well as a drill bit for percussive drilling. |
