Rock drill has greater free volume of helical groove relative to axial helical groove length in region of drill remote from drill head

摘要

The device has a drill head (5) with cutting edges (6) of hard material and a shaft (3) with at least one helical path (7) forming a helical groove (2). The free volume of the helical groove relative to the axial helical groove length is greater in the region of the drill remote from the drill head. One helical path has a path height narrowing conically relative to a core diameter along the bore head axis.