Processes of welding wire heating and melting, electrode metal drop formation and transfer in consumable electrode welding largely determine welding efficiency and quality. In its turn, the nature of metal melting and transfer with this welding process is determined by a large number of such physical phenomena as heat and mass transfer, gas(hydro)dynamics, electromagnetic processes, running in arc plasma, on the surface and in the volume of molten electrode metal-drop. This paper gives a review of currently available methods of theoretical investigation and mathematical modelling of the above processes, allowing prediction of such characteristics of electrode metal transfer as drop volume and shape, their thermal and gas-dynamic state, detachment frequency, etc. Advantages and disadvantages of the considered models are analyzed and main directions of their further development are outlined. 37 Ref.,11 Figures.
K e y w o r d s : consumable electrode welding, mathematical modelling, electrode metal drop formationInterest to the problem of metal transfer in consumable electrode welding is due to a number of causes. It is known that formation of electrode metal drop can be accompanied by its overheating, leading to considerable loss of alloying elements contained in welding wire, bulk boiling and spattering of drop metal, closing of arc gap, etc. In addition, metal transfer mode essentially influences the processes running in the weld pool that, in its turn, determines weld formation. Ensuring directed metal transfer in welding in different positions is also important. Therefore, this work sets forth the known theoretical approaches and describes the available mathematical models, allowing prediction of the main characteristics of metal transfer at different technological parameters of consumable electrode welding.Methods of mathematical modelling of drop formation and electrode metal transfer in consumable electrode welding can be conditionally divided into two main groups (Figure 1). The first includes approaches, which enable prediction of just the individual characteristics of metal transfer process, such as drop size and detachment frequency. The main disadvantage of these models consists in that they do not allow determination of drop shape, or describing the phenomena of charge and energy transfer in molten electrode metal, which accompany the considered technological process. The first group includes such procedures as static force balance theory (SFBT) [1][2][3], pinch instability theory (PIT) [4][5][6], as well as dynamic force balance theory (DFBT) [7,8]. The second group includes the model of drop formation in terms of hydrostatic approximation [9-11], as well as models based on equations of motion of viscous incompressible liquid. In its turn, in the subgroup of dynamic models thin jet approximation can be singled out [12][13][14], as well as models based on total system of Navier-Stokes equations [15][16][17][18][19][20]. Let us consider the most widely accepted of the above methods.SFBT. This method is...
