| 摘要 |
PURPOSE:To perform flash welding that minimizes delay of control and allows quick and exact control, by converting current that flows between welded materials into voltage, rectifying it to rectified voltage, and comparing hold voltage obtained from detected maximum voltage with reference DC voltage. CONSTITUTION:A current transformer 7 for detecting the change of AC flash current generated between a pair of members 1, 2 to be welded is attached to the primary winding of a transformer 6. Output of the current transformer 7 is inputted to a rectifier circuit 9 through a resistor 8, and rectified. The output is inputted to a peak detecting circuit 11, and peak voltage of rectified voltage at every half cycle of AC flash current is detected 11. Then, output of the detecting circuit 11 is inputtd to a peak hold circuit 12. Peak voltage of output voltage of the circuit 11 is held continuously at a specified value at every half cycle of AC flash current, and hold voltage that delayed by half cycle is obtained as output voltage. Output voltage of the circuit 12 is inputted to a comparator circuit 13, and compared with reference DC voltage set beforehand by a reference DC voltage setting device 14. Relative moving speed between members 1, 2 is changed to eliminate the deviation. |
