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APPARATUS FOR SINGLE CAVITY INJECTION MOLDING OF OIL SEALS

  • US 3,754,846 A
  • Filed: 01/21/1972
  • Issued: 08/28/1973
  • Est. Priority Date: 01/21/1972
  • Status: Expired due to Term
First Claim
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1. A single cavity injection mold of at least three pieces defining a mold cavity of circular configuration having a common center line, said pieces comprising:

  • i. a mold top defining at least in part a fine orifice into said mold cavity and having an injection conduit connecting said fine orifice with a source of molding composition;

    ii. a mating mold bottom adapted to accomodate and mate with a center piece; and

    iii. a center piece extending through said mold bottom, mating therewith and defining at least in part an interior wall of the object to be molded, said center piece having a frusto-conical lower portion serving as a valve and mating with said mold bottom as a valve seat, a conduit connecting an evacuating means with said valve seat, said center piece being moveable a few thousandths of an inch upward into said mold cavity to open said valve and to free the molded article from said mold bottom, said valve including means for maintaining said valve in an open position as said mold cavity is being closed, evacuating means for placing a vacuum on said mold cavity through said valve means for closing said valve for of injection of a molding composition into said mold cavity.

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