Method and apparatus for enlarging a bore hole

摘要

A method and apparatus for enlarging a straight or arcuate pilot bore hole and the insertion of tubing in the enlarged bore is disclosed, in which the pilot bore hole 10 is enlarged by advancing a larger diameter housing with a conical enlarging head by impacting of a striking body mounted within a housing against the inside of the enlarging head at the forward end of the housing. Fluid jet cutting action is also employed and the pilot hole boring device may be coupled to exert a steady pull on the housing as it is advanced through the pilot bore. The housing may thus be connected to the pilot bore drilling device, with an interposed cushioning device. The fluid jets may be created by nozzle openings in the enlarging head or in a separate device mounted forward of the enlarging head.