Adjusting press platen clearance

Abstract

In a press having a lower stationary platen, an upper movable platen, a hydraulic ram that travels with the upper platen, light-duty cylinders that position the upper platen, and a gate mechanism that closes above the ram to permit the ram to drive the upper platen during compression phases of operation, method and apparatus for adjusting the clearance between the upper and lower platens. A number of cylindrical spacers can be distributed, as desired, between an upper end of the ram and a spacer retaining mechanism located above the gate mechanism. The spacers are shaped to vertically interlock to form a stable stack atop the ram. The retaining mechanism extends downwardly from an upper cross-head of the press and is received in the interior of the stack of spacers. The retaining mechanism has spring-biased locking members that can locate below an internal lip of any spacer. To remove spacers, the ram is raised until all spacers seated on the ram interlock with any spacers supported by the retaining mechanism. All spacers are then raised until the locking members engage a lowermost one of the spacers to be removed. The ram is then simply lowered, retaining the a desired number of spacers. A similar procedure is followed to add one or more spacers, but a hydraulic cylinder is actuated to retract the locking members to release the spacers.