变极性等离子弧焊接熔透信息的检测与分析

通过对铝合金3003变极性等离子弧穿孔立焊熔池振荡行为的研究，发现熔池振荡频率与焊接熔透之间的内在规律。在变极性电流的作用下，焊接熔池产生振荡，可以通过对电弧电压频谱分析获得熔池固有振荡频率。分别建立变极性等离子弧穿孔立焊未熔透及完全熔透熔池模型，并分析焊接电流的变化对熔池固有振荡频率的影响，发现焊接电流大小对其影响很小，可以忽略。为了验证该模型的准确性，进行理论与实测分析，结果表明，理论值与实测值相吻合。熔池固有振荡频率主要取决于熔池宽度、深度及材料密度等参数，而其他焊接参数对其没有直接影响。因此，熔池振荡频率可间接反映焊接熔透信息，为焊接质量自动控制提供了理论支持。

Detection and Analysis of Weld Pool Oscillation Information for Variable Polarity Plasma Arc Welding

It is discovered the inherent rules between weld pool oscillation frequency and weld penetration though study of weld pool oscillation behavior in the case of variable polarity plasma arc perforated vertical welding of aluminum alloy 3003. During welding, the weld pool is brought into oscillation by variable polarity current, and the oscillation frequency is measured by spectral analysis of arc voltage. The weld pool models of partial penetration and full penetration are established. It is found that variation of welding current has only a small effect on the weld pool oscillation frequency, so its impact can be neglected. In order to test accuracy of the models, it is performed the analysis of theory and measurement, and the results show that two values coincide. The weld pool natural oscillation frequency is dominated by weld pool depth, width and material density and not associated with welding parameters directly. Thus, weld pool oscillation frequency indirectly reflects weld pool penetration, which provides a theoretical support for automatic control of welding quality.