초록 ▼

Apparatus for injection compression molding of thermoplastic parts. A preferred apparatus (100) includes a platen assembly 106, a toggle clamp assembly 102, a screw injection assembly 101, a hydraulic system suitable for providing power to the toggle clamp assembly 102 and the screw injection assemb

Apparatus for injection compression molding of thermoplastic parts. A preferred apparatus (100) includes a platen assembly 106, a toggle clamp assembly 102, a screw injection assembly 101, a hydraulic system suitable for providing power to the toggle clamp assembly 102 and the screw injection assembly 101, and a control system 88 for operatively controlling the various hydraulic devices associated with the molding apparatus. The platen assembly 106 provides for a plurality of variable-volume mold cavities 7. In one embodiment, enlarged mold cavities 7 receive plasticized resin from the screw injection assembly 101, and compression of the injected resin is provided by the toggle clamp assembly 102. In another embodiment, the platen assembly 106 includes a floating die assembly wherein pressure created by injected resin causes die inserts 5 and support pillars 15 to slide relative to a molding plate 74. Compression in this embodiment is also preferably provided by the main toggle clamp assembly 102. Preferably, the toggle clamp assembly 102 provides multiple-stage compression of the resin to first redistribute the resin and vent the cavities and, second, compress the resin to compensate for cooling-induced shrinkage thereof. In the multiple cavity embodiment, because all cavities 7 are equally compressed simultaneously, control of the molding process and balancing of the mold are readily accomplished. The apparatus is particularly well suited for molding optical lenses and disks. Printed circuit substrates can also be molded thereby.

대표청구항 ▼

An Apparatus for forming an article from a molten plasticized thermoplastic resin comprising: a. an injection molding machine system comprising: a plasticating and injecting unit, a clamp system including a fixed platen and a movable platen capable of producing a main clamp force exerted between sai

An Apparatus for forming an article from a molten plasticized thermoplastic resin comprising: a. an injection molding machine system comprising: a plasticating and injecting unit, a clamp system including a fixed platen and a movable platen capable of producing a main clamp force exerted between said fixed platen and said movable platen whereby said main clamp force is driven by a hydraulic cylinder supplied by a hydraulic fluid system, said hydraulic fluid system including at least one control valve in fluid communication with said hydraulic cylinder, a cavity enlargement system, and a molding machine control system for programmably coordinating sequence and motions of the clamp system; b. the cavity enlargement system comprising a moldset disposed between said movable and fixed platens with clamp plates of said moldset fixedly mounted onto said platens, an opposing pair of parting line mold plates between said clamp plates within said moldset, and within at least one parting line mold palte is at least one slidably mounted insert upon which a molded plastic article will be formed, and on one side of the moldset at least one resilient member is mounted between one of said parting line mold plates and said clamp plate, whereby said at least one insert is slidably mounted within said one of said parting line mold plates, wherein a pre-enlarged mold cavity can be formed by changing relative positions of said one of said parting line mold plates and said at least one insert mounted therein, with a pressing stroke thereby being defined as zero when said resilient member is in a retracted position and a pressing stroke of at least 0.060 inch and not greater than 0.350 inch being defined when said resilient member is in an extended position, and before injection has started said at least one insert being initially separated within the pre-enlarged mold cavity to form a cavity volume greater than a maximum volume occupied at atmospheric pressure by the molten plastic resin to be injected into the cavity wherein the volume of said pre-enlarged cavity is determined by a distance between said fixed and movalbe platens; c. clamp system hydraulic isolation means for moving said at least one insert slidably within one of said parting line mold plates, wherein such relative insert motion is driven by corresponding motion of the movable platen, said movable platen being driven by the hydraulic cylinder supplied by a hydraulic fluid passing through at least one control valve dependent only upon programmable control sequences of the molding machine controller whereby compressive clamping force and motions commence before rapid injection fill is completed; d. means for injecting into said pre-enlarged mold cavity a volume of the plasticized resin slightly larger than the volume of the article to be formed but insufficient to fill said pre-elarged mold cavity, said injected resin volume being of at least equal mass as a final molded article of desired dimensions; e. molding machine control system means for controllably pre-enlarging said mold cavity before starting injection, for plasticizing and injecting molten plastic resin, for controllably applying the main clamp force of the injection molding machine before completion of said injection so as to reduce the volume of the mold cavity and driving out gases through vents provided, for controllably maintaining the appied main clamp force until final clamp lock-up position is reached thereby compressing the resin until any slight excess resin is forced into pressure relief means provided and the resin within the further reduced volume mold cavity solidifies and for controllably opening said moldset.