Analysis of instantaneous values of current and voltage parameters in the evaluation of process stability of shielded electrode welding

Abstract

The actual signals of voltage and welding current are the source of valuable information about the quality and stability of the welding process. Digitized voltage and current signals were analysed using a variety of statistical tools, such as mean value of current and voltage (I_sr, U_sr), standard deviation (σ_I, σ_U), voltage and current variation coefficient (K_vI, K_vU), short-circuit time (T_z), glow time (T_j), Carrera coefficient (n), number of short-circuits and the current–voltage histograms. The experimental studies were aimed to examine the possibility of using waveforms of voltage and current welding to describe and evaluate the stability of shielded electrode welding. On the basis of the obtained test results, the voltage indicators calculated on the basis of instantaneous voltage readings appear to be most relevant from the point of view of process description and evaluation of arc voltage stability.