Abstract: Provided is a spot welding method by which welding can be performed successfully while inhibiting occurrence of expulsion. First to third metal plates W1 to W3 were welded in which a ratio of a total thickness to a thickness of the first metal plate W1 is 7. In Example 1, a peak current value A1 is 14.6 kA, an effective current value A2 is 7.8 kA, a peak duration T1 is 0.1 ms, and a no-peak duration T2 is 5.9 ms. As a result, a lower limit current value A3 is 6.9 kA, an upper limit current value A4 is 8.42 kA, a difference A5 between A4 and A3 is 1.52 kA, T2/T1 is 59.0, A2/A1 is 0.53, and rising time T3/falling time T4 is 0.53, furthermore, no expulsion occurs, and a welding result was determined to be OK.

Abstract: A spatter detection method is a method for detecting an occurrence of spatter at the time of joining a workpiece using a spot welding apparatus including a pair of electrode chips, a welding power circuit connected to the pair of electrode chips, and a current sensor configured to detect a current flowing through the pair of electrode chips. A spot welding method using the spot welding apparatus includes supplying a pulse-shaped welding current to the workpiece, the pulse-shaped welding current being generated when the welding power circuit alternately repeats power distribution control and a power distribution pause over a plurality of cycles while the workpiece is sandwiched and pressurized by the pair of electrode chips. The spatter detection method includes determining, based on a current detection value detected by the current sensor in a power distribution pause section for each cycle, whether or not the spatter occurs.

Abstract: A spot welding method includes supplying a welding current having a pulse-shaped waveform to a workpiece by alternately executing a step of maintaining the welding current within a set peak current range and a step of decreasing the welding current from the peak current range toward a bottom current and then increasing the welding current toward the peak current range when an effective value of the welding current reaches a set target range for a plurality of cycles. The spatter detection method includes measuring a pulse width IW(1), IW(2), . . . in each cycle of the pulse-shaped waveform and detecting the occurrence of spatter when a pulse width difference D(M)=IW(M)?IW(M?1) between a pulse width IW(M) in a target cycle (M-th cycle) and a pulse width IW(M?1) in a cycle immediately before the target cycle exceeds a width threshold value Dth.

Abstract: A spot welding method using a welding apparatus includes supplying a pulse-shaped welding current to a workpiece, the pulse-shaped welding current being generated when a welding power circuit alternately repeats power distribution control and a power distribution pause over a plurality of cycles, and maintaining, under the power distribution control, the welding current within a set peak current range in a peak holding section. A spatter detection method includes: a step of acquiring an average value of voltage detection values Vpv detected by a voltage sensor in the peak holding section for each of the cycles; and a step of determining whether or not the spatter occurs, based on a difference value between an average value of the voltage detection values Vpv in the peak holding section for an N-th cycle and an average value of the voltage detection values Vpv in the peak holding section for an (N?1)-th cycle.

Abstract: Provided is a spot welding method capable of reliably welding a metal sheet laminate while suppressing occurrence of expulsion. In the spot welding method, a pulse current is applied in a first current application step and a second current application step by a DC chopping control method. In the DC chopping control method, a pulse waveform of the pulse current is generated by switching between current application and current application stop to a pair of electrodes 12 and 22 by a current switch 28, a peak current value of the pulse current in the first current application step is set to a value A1 equal to that of the pulse current in the second current application step, and a power of the pulse current in the first current application step is set to a value larger than that of the pulse current in the second current application step.

Abstract: Provided is a spot welding method by which welding can be successfully performed while inhibiting occurrence of expulsion. First to third metal plates W1 to W3 were welded in which ratio of total thickness to thickness of the first metal plate W1 is 7. In Example 1, peak current value A1 is 14.6 kA, effective current value A2 is 7.8 kA, peak duration T1 is 0 ms, and no-peak duration T2 is 5.9 ms. As a result, in Example 1, lower limit current value A3 is 6.9 kA, upper limit current value A4 is 8.42 kA, difference A5 between upper limit current value A4 and lower limit current value A3 is 1.52 kA, peak duration T1/no-peak duration T2 is 0, effective current value A2/peak current value A1 is 0.53, and rising time T3/falling time T4 is 0.79, furthermore, no expulsion occurs, and welding result was determined to be OK.

Abstract: This spot welding method is a method for joining workpieces being a layered body of three or more metal sheets by supplying welding current. The welding current has a pulse-like waveform wherein a peak state in which the current reaches or is maintained to be within a set peak current range and a non-peak state in which the current is lowered from the peak current range to a set bottom current, and is then increased toward the peak current range again are alternately achieved. In the non-peak state, in the case where an effective value Irms of the welding current is lowered, and reaches a predetermined effective value target range, a current control process for increasing the welding current toward the peak current range is started.

Abstract: Provided is a spot welding method by which welding can be performed successfully while inhibiting occurrence of expulsion. First to third metal plates W1 to W3 were welded in which a ratio of a total thickness to a thickness of the first metal plate W1 is 7. In Example 1, a peak current value A1 is 14.6 kA, an effective current value A2 is 7.8 kA, a peak duration T1 is 0.1 ms, and a no-peak duration T2 is 5.9 ms. As a result, a lower limit current value A3 is 6.9 kA, an upper limit current value A4 is 8.42 kA, a difference A5 between A4 and A3 is 1.52 kA, T2/T1 is 59.0, A2/A1 is 0.53, and rising time T3/falling time T4 is 0.53, furthermore, no expulsion occurs, and a welding result was determined to be OK.

Abstract: A resistance welding method according to the present invention includes a current control step of sequentially performing a first control for maintaining a welding current being a direct current at a current value I1 (first target value) or in the vicinity of the current value I1, a second control for raising the welding current from the current value I1 to a current value I2 (second target value, I2>I1) and for subsequently maintaining the welding current at the current value I2 or in the vicinity of the current value I2, and a third control for lowering the welding current from the current value I2 to a value smaller than the current value I1, and the resistance welding method further comprises an energization step of applying the welding current while repeating the current control step plural times until a predetermined energization period of time elapses.