Thin-Gauge Steel Spot Welding with Pulsating Current

The patent applies periodic action by using a pulsating welding current with multiple stages (conditioning stage with lower amperage pulses followed by weld pool sizing stage with higher amperage pulses) instead of constant amperage. This periodic variation in current allows controlled heat buildup and prevents rapid melting that causes expulsion, thereby achieving consistent weld nuggets in thin-gauge steel while managing the complexity through programmable current control.

The patent implements parameter changes by dynamically adjusting welding current amperage throughout the welding cycle. The conditioning stage uses lower amperage (e.g., 3-6 kA) to gradually heat the workpiece, then transitions to higher amperage (e.g., 6-12 kA) in the sizing stage. This parameter variation prevents thermal runaway in thin-gauge steel while maintaining weld quality, resolving the contradiction between precision and control complexity.

The patent applies preliminary action through the conditioning stage, which uses lower amperage pulsating current before the main weld pool sizing stage. This preliminary heating phase gradually raises the temperature of thin-gauge steel workpieces, preparing the material for subsequent higher current without causing immediate expulsion. The preliminary action ensures adequate penetration and weld strength while preventing harmful metal expulsion.

The pulsating current with periodic variation in amperage allows the material to respond progressively to heating. The conditioning stage pulses at lower amperage followed by sizing stage pulses at higher amperage create a controlled thermal progression. This periodic action achieves necessary penetration for weld strength while avoiding the sudden thermal shock that causes surface metal expulsion in thin-gauge steel.

The patent implements dynamics by transitioning from static constant amperage welding to dynamic pulsating current with multiple stages. The welding current amplitude, duration, and timing are dynamically adjusted through conditioning and sizing stages. This dynamic control adapts to the thermal response of thin-gauge steel, ensuring consistent weld quality and high reliability for weight-reduced vehicle bodies using steel as thin as 0.3 mm.

The patent applies parameter changes by varying current amperage, pulse duration, and timing throughout the welding cycle. The conditioning stage uses specific amperage parameters to prepare the workpiece, then the sizing stage adjusts parameters to achieve proper nugget formation. These parameter changes ensure reliable, consistent welds in thin-gauge steel, enabling weight reduction in vehicle bodies without sacrificing weld quality.