Optimisation of welding parameters in pulsed MIG/MAG welding with width-controlled sine-wave current pulses. Part 2: Determination of an optimum material transfer through the arc and a control method

Abstract

The paper treats synergic pulsed MIG/MAG welding with width-controlled sine-wave current pulses. Such a pulse-current waveform will be obtained if a power source is controlled by thyristors integrated in a power circuit with a constant pulse frequency. A momentary pulse current power, which is a product of a momentary value of current and voltage, can be controlled by the delay time of thyristor ignition. The paper focuses on an analysis and optimisation of the material transfer through the arc using a limiting criterion determined by an isoparametric equation. By means of the results obtained in the investigation, a parametric diagram with the optimum welding region for a chosen droplet volume transferred through the arc can be determined. The material transfer established will satisfy the criteria set to ensure a stable droplet transfer with no spatter and production of a sound weld. It turned out that the type of synergic welding device suggested for pulsed MIG7/MAG welding was suitable for the most exacting applications.