SCHWEISSGERAET, INSBESONDERE ZUM VERSIEGELN VON MINDESTENS ZWEI UEBEREINANDERLIEGENDEN FOLIEN AUS THERMOPLASTISCHEM KUNSTSTOFF

摘要

A welding device for welding together at least two superimposed foils of thermoplastic synthetic material includes an electrically heated temperature-controlled sealing roller and a counterpressure organ cooperating with roller to form a heated zone in which the foils are tightly welded while pressure is applied thereto. The sealing roller comprises a circular disk-like PTC (positive temperature coefficient) resistor which serves as the heating element and the temperature control, with the PTC resistor having a resistance characteristic which rises steeply in the range of the operating temperature of the sealing roller. The PTC resistor serving as the heating element comprises the effective part of the sealing roller which acts directly on the foils to be welded and has axially opposite electrically conductive end faces each provide with a disk-like metallic contact surface rotatable with the resistor and in electrical contact with the axial end faces. The welding device includes means for supplying electric heating current to the disk-like resistor through the axial end faces thereof via the contact surfaces.