| 摘要 |
PURPOSE:To control accurately a temperature gradient suitable for generation of a nugget and improvement of the quality, by detecting a welding current effective value in every one cycle of power supply and operating and controlling an ignition phase of the next cycle so that this detected value coincides with a target value. CONSTITUTION:An initial value setter 2 sets the first current value when a welding current effective value should be changed. A final value setter 3 sets a current value at the completion time of change, and a cycle number setter 4 sets a time from the start of change to the completion with one cycle of the power source frequency as a unit. A target value operator 5 subtracts the value of the initial value setter 2 from the value of the final value setter 3 and divides the subtraction result by the value of the cycle number setter 4 to calculate the quotient, namely, a current variation per one cycle. This obtained value is added to the initial value in every one cycle of power supply during the time corresponding to the value of the cycle number setter 4. |
