Abstract: A welding machine has a press-on and advancing movement device with two press-on rollers which are arranged one after the other and are driven jointly, a press-on belt being looped around the press-on rollers. The front roller, as seen in the traveling direction, is supported in such a way that it can be lifted when traveling over uneven surfaces so that straight running is maintained. To improve this further, the two traveling rollers which run in advance and are arranged so as to be laterally offset are supported at a swivel plate so that the traveling track can be adjusted. Further, the shaft of the two traveling rollers is not directly driven, but rather a slip clutch in the form of two rubber blocks is arranged between it and a separate drive shaft. The latter as well as the two press-on rollers are synchronously driven by a motor by way of a toothed belt.

Abstract: For the purpose of providing satisfactory, tight welding of overlapping sheet edges and also when passing over uneven surfaces, a press-on roller and two travel rollers are synchronously driven by a drive motor and toothed belt at a traveling, L-shaped machine frame. The travel rollers are laterally offset to the track of the press-on roller, whereby an oblique position of the press-on roller does not occur even in the case of relatively great sheet thicknesses. A heating nozzle running along in front of the press-on roller engages between the sheet edges and forms a pocket, for the lateral closure of which a hold-down is used. The hold-down has a press-on belt rotating in the travel direction and rolling off on the sheet edges, is mounted with vertical play on the frame, and is driven from the press-on roller.