Method and apparatus for compression molding plastic articles

An apparatus for compression molding a plastic article comprising

• a first upper tool assembly having a male mold associated therewith,
• a second lower tool assembly having a cavity mold associated therewith, said cavity mold having a peripheral portion and an inner central portion, said peripheral portion of said cavity mold and said inner central portion of said cavity mold having limited relative movement with respect to one another,
• a first fixed cam for moving said first tool assembly relative to said first tool assembly and a second fixed cam associated with said second tool assembly for moving said second tool assembly relative to said first tool assembly,
• a fluid cylinder having a fluid filled chamber at a predetermined pressure and having a piston interposed between said second fixed cam and said second tool assembly to provide a constant limiting molding force during the forming of the plastic article under the actuation of the fixed cams, said central portion of said cavity mold being associated with said piston of said fluid cylinder such that there is limited permissible movement between said fluid cylinder and said second tool assembly,
• means for moving said first and second mold assemblies relative to said cams to move the first and second mold assemblies toward one another to close the mold and compress a charge of extrudate in the cavity mold.

An apparatus for compression molding plastic articles comprising

• a base,
• a turret rotatably mounted on said base,
• means for rotating said turret,
• an upper annular array of segments removably mounted on said turret,
• a plurality of upper actuators removably mounted on each said upper segment,
• a lower annular array of segments removably mounted on said turret,
• a plurality of lower actuators removably mounted on each lower segment,
• an annular upper cam on said base for engaging and moving the upper actuators downwardly,
• a lower cam on said base for engaging and moving the lower actuators upwardly,
• a plurality of first mold assemblies each associated with an upper actuator and having a male mold associated therewith,
• a plurality of second mold assemblies each associated with a lower actuator and having a cavity mold associated therewith,
• said cavity mold having a peripheral portion and an inner central portion having limited relative movement with respect to one another,
• a fluid cylinder having a fluid filled chamber at predetermined pressure and a piston associated with each said second mold assembly said piston engaging said central portion of each said cavity mold, such that as said turret is rotated, the upper and lower actuators and associated mold assemblies are moved along the cams to move the mold assemblies toward one another to close the mold and compress a plastic charge in the cavity mold, the fluid cylinder providing a constant limiting molding force during compression of the charge.