Study on stability of laser double arc hybrid welding process based on LLE

In order to obtain a stable laser double arc hybrid welding process, the space reconstruction technique was used to calculate the largest Lyapunov exponent(LLE) of the characteristic current in the welding process with different wire spacing. The theoretical analysis and experimental verification experiments were carried out. LLE and its standard deviation data of the welding current with different wire spacing were obtained, When the laser was located in the center of two arcs, LLE was less than 0.61 and the distance was 3mm~9mm, the heat source coupling was good and the welding process was stable. When the welding wire spacing was 7mm, the weld surface was smooth and the penetration was the largest. LLE can be used as the criterion of welding stability, and it was in good agreement with the observation results of electric signal, arc shape and droplet transfer. This result was helpful to ensure the stability and safety of welding process.