Press for hard foam plates

A process for the production of a rigid polyurethane foam panel with a press for the production of a rigid foam sheet comprising:

• a) a frame,
• b) a stationary press plate arranged on the frame,
• c) a movable press plate arranged on the frame,
• d) at least one threaded spindle arranged between the movable press plate and the frame,
• e) at least one hydraulically movable lifting cylinder arranged between the movable press plate and the frame,
• f) at least one hydraulically movable short-stroke cylinder the movement of which is limited by stops that is arranged between the movable press plate and the threaded spindle comprising:
• 1) hydraulically extending the short-stroke cylinder to its limit stop,
• 2) extending the threaded spindle and lifting cylinder in the direction of the stationary press plate in a manner such that the movable press plate moves toward the stationary press plate to establish a predetermined space,
• 3) introducing a liquid polyurethane reaction mixture into a mold,
• 4) arranging the mold in the space between the stationary press plate and the movable press plate,
• 5) allowing the polyurethane reaction mixture to foam and cure,
• 6) retracting the short-stroke cylinder, and
• 7) returning the threaded spindle and lifting cylinder to an unextended position.