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Method for heating plastics materials

  • US 4,076,071 A
  • Filed: 10/22/1974
  • Issued: 02/28/1978
  • Est. Priority Date: 10/22/1973
  • Status: Expired due to Term
First Claim
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1. A method of heating an essentially tubular thermoplastic parison, comprising the steps of placing the parison at a first temperature in a thermal conditioning zone in simultaneous heat exchange relation to both an elongated array of infra-red heating elements and a source of a gaseous coolant, displacing the parison transversely along the array of heating elements (a) while simultaneously subjecting the parison to both heat from the infra-red heating elements and a stream of gaseous coolant issuing from said source, and (b) while rotating the parison about its longitudinal axis so that the exterior surface of said parison is both heated and cooled to avoid localized overheating and consequent heat degradation of the parison surface, and then displacing the parison from the thermal conditioning zone at a second temperature greater than the first temperature, wherein the parison at the second temperature is deformable and workable.

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