JPS57149074A - Method and device for controlling output of resistance welding machine - Google Patents

Abstract

PURPOSE:To prevent the production of expulsion and surface flash owing to control delay and to obtain good welding quality in relation to controlling of the output of a resistance welding machine by meausring intertip voltage and executing prescribed controlling. CONSTITUTION:Voltage between electrode tips 3 and 4 is detected and the integrated value during the half cycle of the first or second half is determined with an integrator 8. The above-mentioned integrated value of the predetermined electricity conduction cycle and a reference voltage E0 are compared in a comparator 9, and when the voltage E0 is higher than ssid integrated value, the conduction angle of a controlling rectifier element 1 is so controlled as to be widened (to be narrowed in an oppositw case). This device is so controlled that in the next electricity conduction cycle the above-described fresh integrated value and the reference voltage obtained by subtracting prescribed quantity DELTAE from the voltage E0 are compared and that according to the magnitude thereof the controlling similar to the one mentioned above is repeated successively. When the integrated value and the reference value are equal, the conduction angle is not changed. In this way, the production of expulsion and surface flash, etc. owing to control delay is prevented.