| 摘要 |
The invention relates to a drill rod having an external thread 11 at one end and a sleeve 13, made of a material that is softer than the material of the thread 11, mounted on the thread 11. The sleeve includes an external thread 15 which engages internal threads 17 of an extension sleeve 16. The thread 11 is made of steel material while sleeve 13 is made of a bearing material such as bronze surfaces 18 and 19 of the rod end and the sleeve respectively frictionally engage with each other to prevent relative axial displacement. Circumferenfially spaced upsettings 21 on the sleeve 13 ensure locking of the sleeve. Locking can alternatively be achieved by brazing or adhesion. The sleeve 13 may vary in thickness with thickened portions being between the shoulders 22, 23 of a thread connection of the rod end. The rod includes a bore 12 for supplying flushing medium. <IMAGE>
|
