Abstract:

In order to reveal the mechanism of the twin-wire co-pool gas-shielded metal arc welding (TCGMA W) and to optimize the corresponding welding parameters , the mathematical model describing the fluid flow in the molten pool is investigated. After analyzing the surface deformation of the molten pool , a body-fitted coordinates transform is introduced to change the complex physical boundaries resulting from the surface deformation into the regular ones in non-orthogonal body-fitted coordinates , which makes the coordinates accord well with the calculated region.Then ，a discrete goveming equation in body-fitted coordinates is established and the energy and momentum boundary conditions are thus dispersed. Moreover , a 3D quasi-steady model is proposed to numerically simulate the fluid flow in the molten pool during the TCGMA W process. Finally , the SIMPLEC algorithm is adopted to simulate the welding process. The results indicate that the proposed method effectively solves the coupling problems among the surface deformation , the fluid flow and the heat transfer with good accuracy.

Key words: twin-wire co-pool gas-shielded metal arc welding, body-fitted coordinates, molten pool, fluid flow, mathematical model, numerical simulation