| 摘要 |
<p>Stabilising fins, lightly spirally shaped in the direction of rotation, and with an angularly contoured fin end, are fitted at intervals on the periphery of a tube section, to stabilise a drill rod assembly used for horizontal drilling. The end parts (3) of the fins (2) are bent into a moderate scoop shape on the side facing away from the direction of rotation, and in the foremost part (e) they converge in an acute angle. The size of their setting angle (alpha) is selectable in accordance with the number of revolutions of drill rods, dia., and the slurry weight. This is simple and inexpensive, and facilitates evenly distributed removal of drilled material.</p> |
