METHOD AND DEVICE FOR HEATING PREFORM FOR BIAXIALLY ORIENTING BLOW MOLDING, AND PRODUCTION OF BOTTLE

摘要

PURPOSE: To uniformly heat a thick-wall preform made of a plastic material having a large change in dynamic viscoelastic properties to a temperature change at a blow molding temperature and thereabouts. CONSTITUTION: A preform (having a wall thickness of 6 mm in a body part) made of a PEN resin is heated for 30sec by a near infrared radiation heater until the outer surface temperature of the body part is increased to 120 deg.C and the inner surface temperature thereof is increased to 90 deg.C Next, the preform is heated for 90sec by a dielectric heater, whereby the inner surface temperature approximates to the outer surface temperature. When the inner and outer temperatures both increase to 150±deg.C suitable for molding and have a temperature difference of 3 deg.C or lower, heating is completed, and a blow molding stage is started. A mandrel is provided so as to run in a gap between the near infrared radiation heater and a radiation heat-reflecting plate opposed to each other and a gap between the dielectric heater and the radiation heat-reflecting plate opposed to each other. The preform is fitted into the mandrel in a vertically inverted state to be heated while being rotated on its axis and moved.