Abstract: An apparatus for welding a web of material which is being moved in its longitudinal direction is disclosed. The apparatus comprises a movable welding tool which welds along a line of contact against the periphery of a rotatable counter-roller, and a drive means which imparts rotary movement to the counter-roller and moves the welding tool periodically into its welding position. The apparatus further comprises a means for superimposing on the counter-roller rotation an additional rotation such that the point of weld contact on the counter-roller is distributed equally around the periphery of said roller.

Abstract: A displacement device in a thermoplastic web welding apparatus withdraws the leading edge of the web from the welding apparatus during pauses in feeding and/or production to prevent melting and sticking of the leading edge.