PERFECT PROCESS FOR THE USE OF GAS ASSISTANCE IN THE MOLDING OF A PLASTIC ARTICLE IN AN INJECTION MOLDING SYSTEM AND PROCESS FOR INJECTION MOLDING OF A PLASTIC ARTICLE

摘要

A method of gas-assisted injection molding in which a first charge of pressurized gas is injected into the mold, but not into the article-defining cavity. The gas charge is of a predetermined pressure sufficient to assist in filling out the article-defining cavity with resin and promoting surface quality. A second charge of pressurized gas may be introduced into the mold at a location remote from a first resin flow path by which the resin entered the article-defining cavity. The second charge of gas is of a pressure and quantity sufficient to enter the article-defining cavity but not into the first resin flow path. In the embodiment of FIGS. 9 and 10, the second charge of gas is directly introduced into the article-defining cavity. In the embodiment of FIGS. 4 through 8, the second charge of gas is introduced into a resin reservoir in communication with the article-defining cavity by a second resin flow path. Alternatively, when introduced to the resin reservoir, the second charge of gas is of a pressure and quantity sufficient to enter the resin reservoir and the second resin flow path but not into the article-defining cavity.