Drill for percussion drilling machines

摘要

The chucked length (6) of the drill (1) is reduced by the axial travel of the hammerdrill (12) and a seal (14) is interposed at spacing from the drill shank rear end (11) so as to seal the drill shank (2) off from the chuck (7). The length reduction amounts to10-20 mm and the effect is to cushion the striker impact so as to preserve hole integrity without spalling or break-out.