PURPOSE: To maintain the specified penetration depth of a stud to be welded and prevent the generation of variance in welding strength by detecting momentarily welding current and controlling automatically the conduction time of welding current so that an integrated value attains a specified value.
CONSTITUTION: The integrated value of the welding current to be supplied to a weld zone is set. The output voltage of a current/voltage converting circuit 2 and the output frequency of a current/frequency converting circuit 3 are different from prescribed values if the welding current fails to attain a set current value when welding is started by feeding a welding start signal to a switching device 5. A digital counter 4 outputs a count-up signal and interrupts the welding current to be supplied to the weld zone. The integrated value of the welding current to be supplied to the weld zone attains the same value as the set value. The welding current meeting the preset integrated value is thus supplied as the preset value by the preset switch and therefore the stud is penetrated to the uniform depth and is welded to the base metal with the uniform strength.
UCHIUMI AKIHIRO
NAKANE YUTAKA
YUBA TSUTOMU
OSAKA DENKI CO LTD