Injection molding method

  • US 5,246,646 A
  • Filed: 04/15/1991
  • Issued: 09/21/1993
  • Est. Priority Date: 11/02/1988
  • Status: Expired due to Term
First Claim
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1. A method of gas assisted injection molding of a plastic part comprising the steps of:

  • (1) injecting molten plastic into a mold;

    (2) introducing gas into the plastic from a source of gas at a preselected pressure;

    (3) monitoring the gas pressure during step (2) upstream of said mold; and

    (4) using the monitored gas pressure as feedback to control the gas pressure injected into the mold during step (2) to ensure that said monitored gas pressure remains substantially constant and at the preselected gas pressure during step (2).

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