NUMERICAL MODEL OF METAL TRANSFER USING AN ELECTRICALLY CONDUCTIVE LIQUID

In order to understand the mechanism of the metal transfer process, the numerical model, which enables to calculate the time-change of liquid transfer process, was constructed. By using the model, we numerically investigated the influence of liquid properties and electro-magnetic force on the modes of liquid transfer. It is shown that liquid transfer modes depend on the pressure balance at the tip of drop. When the dynamic pressure induced by liquid flow is lower than capillary pressure due to surface tension at the tip of liquid drop, globular transfer occurs. In contrast, when the dynamic pressure of liquid flow is higher, spray transfer occurs. In the case that the electrical current flows in the liquid, electro-magnetic force significantly influences on the transfer mode and the drop detachment Calculated results using physical properties of molten mild steel show that electro-magnetic pinch force induced by higher current than 250 A changes the transfer mode from globular to spray, for liquid flow-out from the nozzle of 1.2 mm in diameter. Whereas in real GMAW with pure argon gas shielding the transfer mode changes at around 230 A. The behaviour of drop detachment is varied by both spatial distribution and time-change of the electro-magnetic force.