Ground drilling via pilot holes, comprises rotating cylindrical head with endface angled one side for steering, and with fluid jet fed via annulus between inner and outer drill-rod once plugged together as pilot tube

摘要

The head of the drill is cylindrical and set on a rod (100) composed of fixed outer pipe (1) and a rotating inner pipe (2) which is of smaller diameter and drives the head. The annular space (3) between the rod pipes is connected to the jet emitting pressurized drilling fluid at an angle onto the head steering face. The rod (100) consists of a number of pilot tubes (50) and has slide bearings (5,8) at start and end of the tube. The bearings in the rod space (3) are drilled out (6,9) complete with flexible non-return diaphragm seals (7). The pilot tubes plug together as the pipes (2,3) are smaller in outside diameter at one end (19) than the other (20), with cross grooves (12) at the larger diameter end of the outside pipe as against a ring groove (16) at the other smaller one (19).