Apparatus for heating portions of container preforms

Abstract

Apparatus for heating longitudinally extending portions of a blow molding preform in order to provide a non-symmetrical temperature distribution about a longitudinal axis of the preform. The non-symmetrical temperature distribution permits the preform to be blown to form a non-symmetrical article that has an essentially uniform wall thickness distribution. An auxiliary heating and transfer station is provided between a reheating station and a blowing station, the auxiliary heating and transfer station including two side-by-side pairs of heating elements that are adapted to heat sequentially, corresponding sides of each of a pair of side-by-side blow molding preforms carried by a pallet. The two zone auxiliary heating arrangement permits the desired temperature rise to be achieved consistently while retaining some process flexibility. One or more of the heating elements in the second zone of the auxiliary heating and transfer station is mounted in a manner which allows it to be temporarily repositioned out of the preform movement path. In the preferred embodiment a pivotable turntable is used to shift the associated heating element by 90.degree., thereby permitting transverse movement of the pallet and associated preforms in a direction toward the blow molding station.