Tool unit for the automotive industry, to punch holes or ram fasteners, has a pressure limit valve at one piston to open on an overpressure and allow hydraulic fluid to flow out of the pressure zone

摘要

The tool unit (2), to punch holes in sheets or ram fasteners, has a hydraulic power cylinders (4) for an hollow piston rod (14) with an axial movement within it, with two telescopic piston rods (16,18) each connected to a piston (22,24). A pressure limit valve is in one piston (24) so that, on an overpressure in the pressure zone (28), it opens for hydraulic fluid to flow out of it and the coupling is disengaged between the two piston rods.