Resistive Spot Welding High Stack Ratio Metal Sheets

The patent applies parameter changes by modifying the current waveform from traditional single-pulse to multi-pulse sequences with varying amplitudes and durations. Specifically, it uses a first current pulse at a first amplitude followed by a second current pulse at a second amplitude, where the ratio of amplitudes and durations is optimized to achieve reliable welds in high stack ratio configurations. This parameter optimization enables structural-grade welds without requiring complex specialized equipment.

The patent makes standard servo-gun style spot welders universal by equipping them with programmable power sources that can execute multi-pulse current sequences. This allows a single standardized device to handle both traditional low stack ratio welds and high stack ratio welds by simply changing the current waveform parameters. The system achieves multi-functionality without requiring multiple specialized devices, thereby reducing overall device complexity and cost while maintaining weld reliability.

The patent applies periodic action through the use of multi-pulse current sequences where current is applied in discrete pulses rather than continuously. The first current pulse creates initial heating and metallurgical conditions, followed by a second current pulse that completes the welding process. This periodic application of current enables effective welding of thick stacks by delivering energy in controlled stages, achieving the productivity of multiple tips while maintaining single-tip device simplicity.