Research On Dynamic Information In Micro-plasma Arc Image With High Frequency Pulsed Current

Two-dimensional image of arc which records abundant information of arc, not onlyincludes the morphological characteristics of arc, but also contains light intensitydistribution of thermal radiation. The arc images recorded by high speed photographytechnology can record the shape of arc and the dynamic process of light intensitydistribution and other aspects while welding current is variational. Shape of micro-plasmaarc and light distribution of thermal radiation is influenced by arc welding processingparameters, nozzle size and surrounding environment, is closely related to welding stability,welding heat circulation, weld pool and so on.The photos of pulsed micro-plasma arc are recorded by high-speed photographytechnology with different parameters of pulse. Basing on the image processing technology,the software platform was developed by LabVIEW software programming with G langue,the extraction of parameters on dynamic behavior of pulse micro-plasma arc is realized,dynamic behavior of arc mainly includs micro-plasma arc radius along the axis of eachposition, arc images equal-gray line and sum of gray of arc image and other data.The dynamic process in research is mainly refers to the shape of micro-plasma arc,the energy of thermal radiation, light distribution of thermal radiation when the weldingcurrent increases or reduces rapidly. The morphological characteristics of arc ischaracterized by the radius of the arc along the axis of the arc two-dimensional image ineach position, the influence and the change rule of the dynamic process of arc shape withdifferent and pulse duty are studied.The gray level distribution of arc two-dimensional image reflects indirectly the lightintensity distribution of thermal radiation. The equal-gray line of the arc reflectsequal-light-intensity line of thermal radiation, the influence that pulse frequency andwelding current on thermal radiation with different pulse duty can be got. The risingprocess and failling process of the welding current with that of the sum of the gray level of the arc zone are analyzed by contrast. Research shows that the change of arc energy ofthermal radiation lags behind the change of welding current.In pulsed micro-plasma arc welding, arc shape, temperature distribution and arcenergy are different with the different parameters of the pulse current, and formation ofwelding seam is different. Base on analysis of the relationship between arc characteristicsand shape of welding seam, influence of arc characteristics on welding seam forming canbe discussed, the theory support for improving the welding process is provided.