Apparatus for processing polyethylene terephthalate preforms
AssigneeThe Continental Group, Inc.
InventorsSuppayan M. Krishnakumar, John F. E. Pocock, Gautam K. Mahajan, John F. Trembly
Life of this patent
Estimating the term…
Abstract
This relates to the heating of polyethylene terephthalate by way of RF energy. It has been found that if polyethylene terephthalate articles are passed through a radio frequency energy field, the molecules thereof will become excited and rapid heating will result. This heating is particularly useful in the heating of preforms prior to the blow molding thereof and by varying the configuration and relationship of electrodes, controlled heating of the preforms may be effected with it being possible to have a controlled temperature differential along the length of the preform or other article so heated.
Claims9
Apparatus for heating a molded thermoplastic hollow preform having a closed bottom, said apparatus comprising an electrical supply of the radio frequency type and having a voltage not in excess of the dielectric breakdown of the thermoplastic material, a pair of electrodes disposed in side-by-side transversely spaced relation and defining a preform path therebetween, conveyor means for conveying preforms along said path in spaced parallel relation to one another and in spaced relation to said electrodes, while rotating the preforms about their axes, means connecting said radio frequency electrical supply to said electrodes for forming therebetween along said path a radio frequency energy field, said electrodes having a relationship other than being identical and in parallel aligned relation for effecting controlled heating of selected portions of preforms.
Apparatus for heating a molded thermoplastic hollow preform having a closed bottom, said apparatus comprising an electrical supply of the radio frequency type and having a voltage not in excess of the dielectric breakdown of the thermoplastic material, a pair of electrodes disposed in side-by-side transversely spaced relation and defining a preform path therebetween, conveyor means for conveying preforms along said path in spaced parallel relation to one another and in spaced relation to said electrodes while rotating the preforms about their axes, means connecting said radio frequency electrical supply to said electrodes for forming therebetween along said path a radio frequency energy field, said radio frequency electrical supply being of the variable power type, detector means for detecting the individual temperature of heated preforms, and control means for said power of said radio frequency electrical supply coupled to said detector means for varying said power in accordance with detected preform temperature to provide uniform heating of adjacent moving preforms.
Dependencies are inferred from the claim text.