Interrelation Analysis of Droplets Moving Morphology of Rotating Spray Transfer in MAG Welding

MAG welding with the droplet rotating spray transfer is a high efficiency welding method used in steel structures. It can also avoid some defects,such as the lack of fusion,when used in narrow gap welds and fillet welds. In this paper, the transfer morphology of the droplets was obtained by means of the high speed camera during MAG welding with Ar+O₂ shielding gas when rotating spray transfer was formed. An interrelation analysis model of the molten metal tip and the liquid metal stream was proposed, and the droplet movement and the corresponding rotating parameters were analyzed with the proposed model. It is shown that the interrelation analysis method suggested in this paper can be used to determine the initiative-passive relation between the molten metal tip and the liquid metal stream. During the pulsed rotating spray transfer, the tip and the stream moved around the wire's axis, but their rotating speeds were not exactly the same. The rotating radius of the stream was related with the deflection angle of the tip. Besides, it is observed that the movement of the tip played a leading role in the moving system composed of the tip, the stream and the cathode spot, and the cathode spot played a dragging role for the tip and the stream. The unequilibrium forces that acted on the anode spot were the main causes to affect the droplets' rotating spray transfer.