Emhart Inc.

Jorg Hofmann

Reinhold Opper

Klaus Gisbert Schmitt

Hans Wiessler

Harald Knetsch

Roland Kurz

Kurt Liebich

Alois Bauer

The invention relates to a method of welding weld studs to a workpiece, in particular of aluminum in each case, by the stroke ignition method, in which the stroke height(s) of the weld stud (1) is altered as a function of the measured arc voltage and optionally of the arc firing time. In particular, the stroke height(s) of the stud (1) can be increased during the occurrence of short circuits, i.e. during a sudden drop in the arc voltage, preferably in predetermined steps. The weld stud is immersed into a pool of melt after a predetermined period of time of between 5 and 10 ms after the welding current has been switched off. The polarity of the stud or of the workpiece is changed at least once during the welding process. The welding current is interrupted for a predetermined period of time for this purpose. The method leads to an improved, readily reproducible quality of weld.

Method of welding weld studs to a workpiece

Process for welding a weld-in part in a weld point comprising a metal plate and a metal covering lying thereon with two tools of which one is formed by a welding head and the other by a drill for preparing the weld point by a drilling process. The drill attached to a revolving device initially in one operating position, by means of a lifting motor which can be moved in a controlled manner between a return position and a machining end-position and vice versa, performs the process at least until the metal plate is drilled (machining end-position) in preparation of the weld point. By pivoting of the revolving device, a welding head arranged on the revolving device and equipped with the weld-in part is then brought into an operating position above the prepared weld point to perform welding, meanwhile the drill is coupled to the lifting motor when the welding head is coupled to the lifting motor when the drill is uncoupled to perform welding on completion of the drilling process. Drill and the welding head are each set aside in their return position on a rest shoulder after pivoting of the revolving device, the welding head being equipped with a weld-in part in the rest position and the revolving device pivoting the drill or the welding head into the respective operating position from the rest position.

Process of and machinery for joining two metal sheets by welding

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Giessen, Germany

Jorg Hofmann