| 摘要 |
<p>PCT No. PCT/SE95/01381 Sec. 371 Date May 20, 1997 Sec. 102(e) Date May 20, 1997 PCT Filed Nov. 21, 1995 PCT Pub. No. WO96/16246 PCT Pub. Date May 30, 1996A thread coupling for percussive drilling has a first drill string element (2) with an internal thread (3) and a second drill string element (6) with a spigot (7) which is provided with an external thread (8) for cooperation with the internal thread (3). A contact surface (10) on the second drill string element (6) is lined with a wear resistant additional material which covers 50-100%, preferably, 50-90%, of the contact surface. The wear resistant material is preferably a stellite which has been applied by means of plasma welding, or is a ring which has been soldered to the contact surface.</p> |
