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Method and apparatus for preventing thermal damage to a preformed plug during molding of a housing therearound

  • US 4,430,285 A
  • Filed: 10/23/1981
  • Issued: 02/07/1984
  • Est. Priority Date: 10/23/1981
  • Status: Expired due to Fees
First Claim
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1. A method of forming a rotary plug valve of the type comprising a housing formed of a polymer and a rotary plug disposed in a through-passage of said housing;

  • providing a rotary plug having a bore extending diametrically therethrough and formed of a polymer;

    forming a shell-like shield of a resilient polymeric material of a shape to closedly seat against and cover a portion of the peripheral surface of the plug, attaching the shield by snap-fitting said shield onto said plug with its inner surface conforming to the peripheral surface of said plug;

    positioning said plug and shield assembly within a cavity of a mold on a mold core means for supporting said assembly and forming the through-passage, said cavity corresponding to the shape of said housing, and introducing a molten polymer into said cavity at a point whereat the shield is interposed between the polymer and the plug to shield the plug from the thermal energy of the molten polymer as the polymer is initially introduced into the cavity and to form said housing around said plug and bond said shield to the housing formed by the polymer.

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