Robust sensing of arc length

During are welding, the are heats and melts the workpiece as heat flux. Whe n the welding current is given, the distribution and the intensity of the h eat flux are determined by the length of the are. The measurement and contr ol of the are length are fundamental in robotic and automated welding opera tions, Length of welding are determines the distribution of the are energy and thus the heat input and width of the weld. This work aims at improving the measurement accuracy of are length using the spectrum of are light at a particular wavelength during gas tungsten are welding (GTAW) with argon sh ield. To this end, effects of welding parameters on spectral distributions were studied. To verify the effects of base metal and are length, the are c olumn was also sampled horizontally as layers for spectral analysis. Result s show that spectral lines of argon atoms are determined by are length, ind ependent of welding parameters other than the current, Based on these findi ngs, a compact are light sensor has been designed to measure the are length with adequate accuracy. A closed-loop are length control system has been d eveloped with the proposed sensor.