Hydraulic press mechanism

A hydraulic press mechanism for applying in succession a fast approach stroke to a tool juxtaposed with a workpiece and then a work stroke with substantial stress application to the workpiece, said mechanism comprising:

• a housing formed with a bore axially aligned with said tool;
• a main body centered on the axis of said bore and received in and axially movable along said bore, said body being formed at an end proximal to said tool with a cylindrical chamber centered on said axis and at an end remote from said tool with a compartment centered on said axis receiving a substantially incompressible fluid, said compartment being connected to said chamber through a passage in said body extending along said axis;
• a secondary piston centered on said axis received in said chamber and operatively connected with said tool for displacing said tool axially toward said workpiece upon hydraulic pressurization of said chamber;
• a primary piston centered on said axis and axially shiftable in said housing and extending into said compartment of said body for displacement of fluid from said compartment through said passage to said chamber;
• coupling means for releasably coupling said body to said primary piston whereby displacement of said primary piston and said body towards said workpiece displaces said secondary piston with said fast approach stroke until said tool contacts said workpiece;
• an expansible casing on said body centered on said axis and exposed to said fluid for expansion by fluid pressure upon engagement of said tool with said workpiece for blocking said body against said housing whereby further displacement of said primary piston into said compartment displaces fluid therein to displace said secondary piston with said work stroke;
• control means including a stem extending along said axis and operatively connected with said primary piston for displacing same, and an actuator displaceable in opposite directions for said stem, said secondary piston being biased by a return spring in said body away from said workpiece;
• and
• sealing means for isolating said actuator from said fluid.