Drilling tool for rotary percussion drilling

摘要

A drilling tool for rotary percussion drilling including: a drilling body defining: a longitudinal centerline axis extending in a drilling direction; a bore extending in a direction of the centerline axis and having a bore bottom; and a recess extending in a direction transverse to the centerline axis and eccentrically with respect thereto. A centering drill is adapted to move in the drilling direction and has a centering drill end, a centering drill shank and a chucking portion having a flattened clearance on one side thereof, the centering drill shank having an end side cylinder section for limiting an axial path of the centering drill during its movement in the drilling direction, the centering drill extending in the bore of the drilling body and the bore bottom being effective as an exclusive stop for the centering drill end when the centering drill is being subjected to percussion stress. A pin-shaped holding device secures and positions the centering drill in the bore of the drilling body and further extends in the recess and penetrates into the bore at a region of the chucking portion of the centering drill for receiving the centering drill, the end side cylinder section being configured for preventing an insertion of the centering drill into the bore when the holding means extends in the recess.