Monitoring of laser-arc interaction process based on selective observation of line-spectrum optical signals

Laser-arc interaction is the key to producing the “1 + 1 > 2” synergistic enhancement effect in laser-arc hybrid welding. This study explores the interaction process between the laser and arc in hybrid welding by collecting the characteristic line-spectrum optical signals from plasma radiation during laser-TIG hybrid welding of 5083 aluminum alloy, combined with signal analysis methods such as empirical mode decomposition (EMD). EMD can decompose the original optical signal into 10 intrinsic mode function (IMF) components, where the high-frequency component IMF2 corresponds to the ionization effect of the arc and the medium-low frequency components IMF6 and IMF7 characterize the influence of laser on plasma characteristic behavior. Increasing laser power, decreasing welding speed, and reducing heat source spacing, all of which enhance the proportion of laser energy in the hybrid heat source, significantly improve the correlation between IMF6 and IMF7 components and the original signal. Increasing arc current significantly raises the correlation of IMF2, suggesting that the arc ionization effect strengthens with the increase in arc energy proportion. The method proposed herein overcomes the generalized analysis mode of traditional broad-spectrum signals, enabling high-sensitivity capture of the interaction intensity and fluctuations between arc plasma and metallic plasma in the keyhole opening region. This approach is expected to advance the development of process signal acquisition in intelligent hybrid welding processes.