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US 4,903,397 AGranted
Process for producing a heating element
AssigneeFriedrichsfeld GmbH Keramik- und Kunststoffwerke
InventorNorbert Freidel
Life of this patent
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AssigneeFriedrichsfeld GmbH Keramik- und Kunststoffwerke
InventorNorbert Freidel
Estimating the term…
A process for producing a heating element comprising a heating wire wound as a bifilar spiral and arranged in a plastic part that can be welded to a plastic pipe by supplying electric current to radially outwardly extending wire ends of the heating wire. The process can be implemented with little effort, and the apparatus for carrying out the process enables functionally reliable production of the heating element. The heating wire is arranged in a bifilar spiral groove in a surface of an injection mold with the windings of the heating wire spaced a distance corresponding to the radial spacing of the individual windings of the spiral groove. After closing the injection mold, plastic is introduced into preferably radial connecting grooves between the windings of the spiral groove so that the plastic at least partially surrounds the heating wire in the vicinity of the connecting grooves.
A process for producing a heating element which is to be arranged in a plastic part and used to weld the plastic part to a plastic pipe, said heating element comprising a heating wire wound as bifilar spiral with radially outwardly extending wire ends through which current can be supplied to the heating element, said process comprising arranging said heating wire in a bifilar spiral groove in a surface of an injection mold with the windings of the heating wire spaced a distance corresponding to the radial spacing of the windings of the spiral groove, closing said injection mold, and introducing plastic into connecting grooves between the windings of said spiral groove so that the plastic at least partially surrounds the heating wire in the vicinity of said connecting grooves.
Dependencies are inferred from the claim text.