Thin Plate Laser Weld Profile for Stronger Back-Side Nuggets

The patent applies periodic action by dividing the laser welding process into multiple stages with different power levels. The laser beam is emitted in a controlled sequence: initially at low power to form a stable nugget, then power is increased in subsequent stages to expand the nugget diameter without causing hole formation. This staged approach allows the weld to progress through different thermal states safely, achieving both strength and reliability.

The patent applies preliminary action by first establishing a stable nugget formation phase at low power before transitioning to higher power stages. The initial low-power emission creates a controlled molten pool that serves as a foundation for subsequent welding stages. This preliminary stabilization of the laser oscillator operation prevents control difficulties that would arise from immediately operating at minimum stable parameters.

The patent applies local quality by creating different nugget characteristics at different locations through staged laser power application. The front-side nugget is formed with controlled diameter through initial low-power emission, while subsequent higher-power stages selectively expand the back-side nugget portion. This localized differential heating achieves small front-side nugget diameter while maintaining adequate back-side nugget diameter for weld strength.