Preheater for differential pressure forming machine

摘要

A preheater and method of preheating a thermoplastic sheet prior to entry of the sheet into a differential pressure forming machine which forms an article in the sheet. The preheater includes mechanism for initially threading a sheet in a generally horizontal plane, mechanism for concurrently displacing upstream and downstream portions of the sheet in vertically opposite directions relative to the horizontal plane to dispose a portion of the sheet in an upstanding plane. A heater is provided for heating the upstanding portion of the sheet in the upstanding plane. After the sheet has been repositioned with a portion in the upstanding plane, the heater is laterally moved from an inoperative position to a sheet heating position receiving the portion of the sheet at the sheet heating station. Mechanism is provided for selectively moving the sheet downstream after the sheet has been vertically displaced.