Injection molding operation, using internal gas pressure technology, directs displaced plastic into adjacent cavity, where it is kept fluid for use in later moldings

摘要

Plastic displaced by gas pressure is conducted to an adjacent cavity where it is maintained liquid. This plastic is not supplied to a cavity to form a molding, until the next cycle, at the earliest. An Independent claim is included for equipment carrying out the operations described. Components are listed: platens (one moving), molds, molding cavity, hot channel nozzle, melt source, gas injector and the novel adjacent cavity. The adjacent cavity (7) is connected (17, 18) to the molding cavity (4) and has a heater (19) keeping the plastic molten. Means of plastic supply from the adjacent cavity, operating no earlier than the next cycle, are included. Preferred features: The adjacent cavity wall is heated. The plastic from this adjacent cavity, is injected before and/or during filling of the mold cavity. It is injected shortly before and/or after completing filling. It is re-supplied to the same location of the mold cavity. Re-supply is achieved using a piston. Supply is to a different part of the molding cavity. Stored material is supplied to the molding cavity during the next cycle. It may be supplied to another molding cavity. In the equipment, the adjacent cavity is contained in an insert. The insert, located on the side away from the cavity, is bordered by a moving slide (9). Actuation is electrical or hydraulic. The adjacent cavity is a channel (14). It is located between the molding cavity and the hot channel nozzle (5) or between two molding cavities. It can be shut off by one or more slide valves (9, 15, 16). Heating (19) is by resistance wires or channels carrying a thermal medium, e.g. a gas or liquid.