Arc sensor sensitivity in short circuiting metal active gas welding with high speed torch oscillation

Abstract

The present paper describes the characteristics of the arc sensor, focusing on the sensitivity of the change in welding voltage and current to the torch oscillation frequency, in the low current and high speed torch oscillation metal active gas (MAG) process. First, a mathematical model of the short circuiting transfer welding is proposed, based on a previously reported model of spray transfer welding. Then, the relationship between the oscillation frequency and the rate of short circuiting was investigated using the proposed model. Numerical calculation results revealed that short circuiting regularly occurs at both oscillating edges at oscillation frequencies close to half the rate of short circuiting obtained under non-oscillating conditions. This finding agrees satisfactorily with the experimental results. Fast Fourier transformation analyses of the signals of welding voltage and current showed that the sensitivity of the change in the voltage and current is maximised at a frequency equal to about half the short circuiting rate obtained under non-oscillating conditions. It is considered that accurate seam tracking by arc sensors in short circuiting MAG welding can be achieved by setting the torch oscillation frequency to the above value.