GROUND DISPLACEMENT DRILL, THEREBY USED DISPLACEMENT HEAD, METHOD OF MANUFACTURE OF A POST, AND THUS MANUFACTURED POLE.

摘要

To the drill pipe connects a head comprising a cylinder-shaped portion and a cone-shaped point. Three spiral ribs are regularly distributed over the head. Each rib has a downwardly-extending rib portion standing on the point and having an outer side making an angle between 0 DEG and 5 DEG with the drill axis and an inner side making with the outer side of the point an angle which is smaller than 90 DEG increased by half the apex of the point, and has a outwardly-extending rib portion standing on the cylinder-shaped head portion and having a top side making an angle between 85 DEG and 95 DEG with the outer side of this head portion. The lowermost edge of the rib portion standing on the point merges into the outermost edge of the other rib portion. The apex of the point lies between 85 DEG and 95 DEG .