Method for injection molding of plastic materials using gas holding pressure in mold
AssigneeLear Corporation
InventorJames W. Hendry
Life of this patent
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Abstract
A system and process for gas-assisted injection molding of plastic materials using gas holding pressure in the mold cavity. An infinitely controlled gas pressure valve is utilized to provide initial pressure in a sealed mold and the gas is vented to a prespecified pressure when plastic is injected into the mold cavity. Additional gas is injected into the plastic material from a gas pin assembly in order to force the plastic to completely fill the mold cavity and to provide a hollow cavity in the completed part. Once the injection molding process has been completed and the part has cooled and solidified, the mold is opened, and the completed plastic molded component or part is removed or ejected.
Claims11
A method of forming an injection molded plastic part in a mold, comprising:
- sealing the mold to prevent gas leakage from the mold cavity;
- applying an initial gas pressure in the mold cavity;
- injecting plastic material into the mold cavity;
- increasing the gas pressure in the mold cavity up to a preselected value;
- injecting gas into the plastic material after 90%-99% of the preselected amount of plastic material has entered the mold cavity;
- venting the gas from the mold cavity at a controlled rate;
- allowing the plastic material to harden forming a hollow molded article;
- venting the gas from the hollow molded article;
- and
- removing the completed plastic article from the mold.
Dependencies are inferred from the claim text.