Flash butt welding of workpieces - where electronic comparator circuit keeps electric power at desired working point

摘要

The process is stabilised while the workpieces are moving together at variable speed along a fixed path/time curve, by measuring an actual value (Ia) representing the electric power or the effective electric current. Value (Ia) is compared with at least two preadjustable reference values (I1, I2) and, if a critical value is reached, the current is automatically altered. The pref. welding machiens include meter feeding signal (Ia) into an electronic comparator using a trigger circuit fed with values (I1, I2); and the comparator actuates an ignitron supplying the machine with two power stages. The occurrence of short circuits is eliminated; and there is virtually no delay in controlling the process even when using a low idling voltage.