Percussion rock drill

摘要

Hammer drill tool (1) for rock (11) comprises a bit shaft (2) having a prismatic cross-section with an axial cylinder bore (3) and at least one radial opening (4), a rotating twist drill (6) protruding into the cylinder bore axially to the bit head (7) and having a drill head (10) with a bit (9), an opposite-lying insertion end (12), and an axial stop (13) arranged in between. The twist drill, forming a stop shoulder on the axial stop, tapers in a stepped manner toward the drill head. Preferred Features: The bit head has axial cutting edges (8) made of hard material which are optionally chamfered inward.