WELDING CURRENT CONTROL METHOD AND DEVICE FOR DC RESISTANCE WELDING EQUIPMENT

摘要

PURPOSE:To provide the welding current control method and device of the DC resistance welding equipment capable of detecting a magnetism deviation phenomenon and controlling a welding current based on this detected result even when the welding current such as having the different pulse width of an A phase pulse and a B phase pulse is controlled. CONSTITUTION:The DC resistance welding equipment 10 is provided with a search coil SC wound round a welding transformer circuit 18, a differentiation circuit 28 which differentiates the output voltage of this search coil SC and outputs the differential voltage VD, a first comparator 32 and a second comparator 36 which compare the differential voltage VD with a threshold set by a voltage setting device 30 and output the compared result. The DC resistance welding equipment 10 is further provided with AND gates 34 and 38 which perform logical product operation of the compared result outputted from the respective comparators 32 and 36 wit the A phase pulse and B phase pulse energizing an inverter circuit 16 and output magnetism deviation phenomenon detection signals VA and VB.