| CPC B23K 11/115 (2013.01) [B23K 11/257 (2013.01); B23K 2101/18 (2018.08)] | 4 Claims |

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1. A spot welding method for joining a workpiece by a supply of welding current, comprising:
a) increasing the welding current toward a set peak current range;
b) decreasing the welding current from the peak current range toward a bottom current, and then switching to the step a); and
c) supplying the welding current having a pulse-shaped waveform in which a peak state are alternately achieved by repeatedly performing the steps a) and b), wherein
in the step b) calculating an effective value of the welding current over a predetermined period while the welding current is in the non-peak state, waiting for the switch to the step a) until the effective value reaches within a set target range, and then switching to the step a) when the effective value reaches within the set target range.
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