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Sheet shaping method

  • US 4,191,039 A
  • Filed: 01/18/1978
  • Issued: 03/04/1980
  • Est. Priority Date: 01/18/1978
  • Status: Expired due to Term
First Claim
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1. A method of shaping a sheet of thermoplastic material, comprising providing a sheet at a temperature sufficient to enable it to be shaped by the application of pressure thereto, placing the heated sheet material into an at least partially enclosed mold and disposed in proximity to a shaping member thereof and therafter directing liquid coolant under a pressure sufficient to maintain said coolant in a liquid state and to enable shaping of said sheet into said mold by the direct contact of said coolant with said sheet so as to force said sheet into contact with said member and thereafter depressurizing said mold so as to permit the vaporizing of at least a part of the same said coolant contacting said sheet material, thus quickly removing heat from the surface thereof by means of the heat of vaporization effect so as to form at least a solidified skin of cooled material on said sheet material surface opposite to that surface contacting said mold member and thereafter removing said sheet from said mold.

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