| 摘要 |
PURPOSE:To compensate welding strength so as to obtain normal nuggets in a resistance welding device by comparing a reference voltage and a differential voltage and regulating the supply of electric current when the welding current is oversupplied and expulsion and surface flash arise. CONSTITUTION:The voltage between electrodes 2a and 2b is detected with a circuit 5, and is subjected to full wave rectification with an A/D converter 6. Said voltage is inputted to a standard voltage storing circuit 7. In a comparator 8, the standard voltage waveform and the digital value of the detected voltage are compared and the difference thereof is applied to an output circuit 9 for phase conversion data, by which the quantity of phase conversion is retrieved and according to the same the supply voltage from an AC power source 4 is regulated by a current control circuit 10 and is supplied via a transformer 3 to the electrodes 2a, 2b. When the welding current is oversupplied and expulsion and surface flash arise, the reference voltage V0 of a reference voltage generating circuit 13 and the differential voltage DELTAv from the comparator 8 are compared in an expulsion and surface flash voltage comparator 14. When the differential voltage exceeds the reference voltage, a control signal is inputted from the circuit 14 to the circuit 9 and the supply voltage is controlled with the circuit 10. |
