Rotary-percussion drill apparatus and method

摘要: A down-hole pneumatic rotary-percussion hammer drilling apparatus (100) is disclosed. The includes a drill string (14) for progressively extending into hole (124) in the earth (81); an elongated housing (4) connected to string; impact bit (104), rotationally coupled (4), having engaging surface (122), impacting (128), channel (121), and plurality of conduits (140, 142) from about exit portion (146, 148) conduits; piston (24) within working fluid (82) handler energizing with fluid. (104) rotatable longitudinal axis, (121) providing path flow portions conduits. are displaced axis (134) extend generally downwardly outwardly. (32) emerges effects rotation axis. Associated method also