Robust sensing of arc length

During are welding, the are heats and melts the workpiece as heat flux. When the welding current is given, the distribution and the intensity of the heat flux are determined by the length of the are. The measurement and control of the are length are fundamental in robotic and automated welding operations, 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 shield. To this end, effects of welding parameters on spectral distributions were studied. To verify the effects of base metal and are length, the are column was also sampled horizontally as layers for spectral analysis. Results show that spectral lines of argon atoms are determined by are length, independent of welding parameters other than the current, Based on these findings, 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 developed with the proposed sensor.