Analysis of short circuit transfer behavior using acoustic signal detection

The stability of a short circuiting period is important to obtain the desired weld quality. The objective of this research is to analyze the uniformity of liquid bridge disruption period during short circuit mode affected by various shielding gas compositions. The shielding gas compositions of 100% CO₂ and 84%Ar+2%O₂+14%CO₂ were used in this study. Short circuiting period was detected by using acoustic signals emitting from the arc. Acoustic data were recorded by using multimedia function of XP windows audio card through a high sensitivity microphone. The results of short circuit acoustic data were analyzed by using continuous wavelet transformation for classifying the difference of acoustic emitting mechanism of electrode tip touching with base metal and pinching cut-off. For 84%Ar+2%O₂+14%CO₂ shielding gas, it clearly showed smoother short circuit transfer than that of CO₂ shielding gas. CO₂ shielding gas gave large variation in disruption period comparing with that of 84%Ar+2%O₂+14%CO₂ gas mixture.