Punch presses

A punching head assembly for a punch press, said punching head assembly comprising a cylinder portion having a first piston member adapted for reciprocating movement therein, said first piston member having a pair of radial work surfaces each defining part of a respective one of a first extend chamber and a retract chamber;

• control means, said first extend chamber and said retract chamber being in respective fluid communication with said control means adapted to alternate a flow of pressurized fluid to said chamber to obtain reciprocating movement of the piston member, said control means comprising valve means controlled by a microprocessor;
• a second piston member juxtaposed axially with said first piston member and having a radial work surface defining part of a second extend chamber which is in controlled fluid communication with said control means, whereby the flow of pressurized fluid to said second extend chamber is selectively opened to drive said first and second piston members together and closed to disable said second piston member, said first piston member being connected to a ram having a punching tool at an operative end thereof;
• and a stripper assembly having a stripper plate at least partially surrounding said punching tool, a hydraulic piston adapted for reciprocating movement axially relative to said ram and being connected to said stripper plate, and valve means operated by said microprocessor for controlling axial movement of said hydraulic piston and said stripper plate independently of said punching tool.