Unit to weld thermoplastic material has spring-loaded resistance wire - above pref. toothed surface of carrier, pref. spring-loaded PTFE protector above wire and member to press material on to wire via protector

摘要

The mechanism for welding thermoplastic material comprises a longitudinal heating element connectable to an electrical power source, a (PTFE) protector between element and material, an element carrier, and a pressure member movable to depress the material on to the element via the protector. In the raised position of the member, the element is not in contact with the carrier whilst, in the depressed posn., it is pref. in contact with the carrier at a number of spaced points only, e.g. with the tops of a toothed profile arranged on the carrier surface.