Punching, stamping and rivetting apparatus

Abstract

A hydraulic punch press having a base adapted to receive a workpiece and a cylinder axially disposed opposite to the base. The cylinder includes a first and second piston slidable defining within its interior, a first chamber formed between the surface of said first piston and one end of said cylinder and a second chamber formed between the first and second pistons. The pistons have coaxial rods extending outwardly of the other end of the cylinder in opposition to said base. The rod of the first piston extends axially through the rod of said second piston and carries at its end a tool while the rod of the second piston is tubular and is adapted to carry at its end holding means for the workpiece blank. Conduit means lead to each of the first and second chambers, from means for alternately delivering, simultaneously to said first and second chamber, hydraulic fluid of high pressure and lower pressure, respectively, to thereby reciprocate the rods of both pistons outwardly in a work phase, and the rod of the first piston inwardly in a retraction phase while maintaining the rod of said second piston in holding engagement with the workpiece blank and the workpiece holder is released and retracted when the second chamber is freed of hydraulic pressure fluid.

Dependencies are inferred from the claim text.