CONCERNING THE MELTING OF AN ALUMINIUM ELECTRODE BY THE ARGON ARC OF STRAIGT POLARITY

This paper gives the information analysis on the ratio of the melting rate of electrode wire on welding arcs of direct and reverse polarity in СО₂. At equal currents, the melting rate on direct polarity arc is about two times higher than the melting rate on reverse polarity arc. When welding in shielding gases, the reason to refuse the use of direct polarity arc is the low melting rate stability of the electrode wire. It is caused by the intense moving of arc cathode spot affected by the emissivity change of the electrode surface. Within the scope of this paper, the authors propose a calculation method for arc power transmitted to a consumable aluminum electrode on various polarities. The calculated specific power (per 1 А of the current) is significantly higher for electrode-cathode, and when step-up the current, the power increases more intensively than for anode. The experiment determined the melting rate of aluminum electrode wire of 1.2 mm diameter for direct polarity arc in argon. It is as well about two times higher than for reverse polarity. Within the limits of 80-180 А currents on the arc direct polarity, there was not defined any significant dependence between the melting ratio of aluminum wire and arc current. The calculation method ensures good convergence of designed and experimental data on the ratio of electrode melting rates on different polarities. The formulas obtained allowed evaluating the effective arc power in argon for aluminum products. Further researches are to be aimed at defining the stability conditions of the melting rate of electrode wire on direct polarity arc in shielding gases. It is especially necessary for welding of heavy thickness parts to reach more efficient filling of edge preparation.

welding arc, consumable electrode, aluminum, direct polarity, remelting stability, shielding gas welding