Chisel and/or hammer drill tool, for working rock materials, has a beating converter which registers a tool caught in the rock, to switch to a free beating mode to give a series of light impacts to release the tool

摘要

The chisel and/or hammer drill has a beating piston with an axial reciprocating movement. In the main striking mode, the piston moves the hammer tool (18) directly over a given path. In a free striking mode, the piston acts on the tool indirectly through a beating converter unit (54). The beating surfaces of a tool shaft (16) and a free beating ram (38) are positioned opposite the beating piston for a return spring (74) to withdraw the ram from the piston working zone. The beating converter unit incorporates a force measurement and switch system. The force is measured to establish the draw forces at the worked material when the caught tool is withdrawn, to switch from a main to a free beating mode if the draw force breaches a given threshold value.