Avaliação do controle da corrente de curto-circuito na soldagem com eletrodos revestidos

Abstract

Power supplies for Manual Metal Arc (MMA) Welding with short-circuiting current electronic control are already available in market. However, no data was found in the current literature, which can be used to compare the efficiency of this new technology with the techonology applied in the conventional power supplies. Therefore, the aim of this present work was to evaluate the influence of the short-circuiting current and the reference voltage (short-circuit control) on the arc stability and on the economics characteristics of the electrodes. To do so, a series of single-V groove joint welds was carried-out with a welder simulator, on flat and overhead positions, using the statistical technique Taguchi’s Method for the experimental design. A secondary-chopped power supply with the capability to set the short-circuit control parameters was used along with a Computer based electrical signal data logger and analyser. The control factors were the reference voltage, the short-circuiting current, the mean current, the welding position and the type of electrode (commercial rutilic, basic and celulosic of 3,25 mm of diameter). In each experiment, the added area of the weld bead was kept constant, by the variation of travei speed. The results indicated that, for the conditions used in this work, there is no detrimental effect in the use of the short-circuit control on the economics characteristics of the electrodes. But it was found some influence of this control on the frequency and the time of the shorts-circuits. Still, it was concluded that the economics characteristics of the electrodes were affected mostly by the welding position, the mean current and the type of electrode.