Numerical Simulation Of Electromagnetic Assisted Arc Direct Forming

Arc direct forming technique is an advanced rapid prototyping technology of highenergy beam based on sedimentary forming principle.However, because PDM is thecomplicated physical process of fast melting and rapid solidification, it is likely to appearthe problems such as incomplete powder melting, droplet collapsing and beading and soon, which have bad effects on material utilization, shape precision, surface quality andperformance of the final parts. In this paper, the electromagnetic assistive technology wasemployed in arc direct forming technique. Alternating current was applied on theelectromagnetic coil, at the same time of the arcing of the welding gun. The generatedalternating magnetic field produced eddy nearby the furnace hearth which was oppositewith the direction of the current in the coil, the electromagnetic repulsion between themcan produce a suspending force for the furnace hearth mental to hold the droplet, avoidingflowing to the two sides, thus enhance the surface quality of the ancillary.We conducted two-dimensional modeling analysis for each structure parameters ofthe coil through the Maxwell12.0software. According to the suspending power suppliedby the coil, the influence of coil diameter, coil taper, field frequency, exciting current andother parameters on the suspending power was analyzed to obtain the optimum parametersof the coil. Three-dimensional modeling was established based on the optimizedparameters to attain the three-dimensional distribution rule of suspending power aroud thefurnace hearth. Rely on this, regression analysis in matlab software can obtain ruleequation. The program constituted by C++software was unloaded in FLUENT fluidsimulation software to proceed three-dimensional fluid simulation. Multiphase transientfield unified mathematical model of electromagnetic assisted arc direct forming wasestablished in fluid simulation. In order to solving the the flow field, temperature field andthe solute diffusion field, an enthalpy-porosity method was proposed to deal with thephysical properties in solid-liquid co-existence region. The control equations werediscretized by using the finite volume method (FVM) method and the SIMPLECalgorithm based on the adaptive non-uniform staggered computational meshes. Theadditional source term method (ASTM) was used to simplified boundary conditions. Finally, the ancillary added magnetic auxiliary showed a great improvement in topography,temperature and internal flow filed of furnace hearth than that without magnetic auxiliary.Several significant parameters in processing were optimized: coil position located at coilcenter lagging welding torch center7mm, inclined Angle up30°, wire feed rate was3.6m/min, walking speed of welding torch was480mm/min and so on.In conclusion, the correctness of numerical simulation result in this paper wasverified through experiment. The research provided scientific grounds and effective toolsfor electromagnetic assisted arc direct forming technology to chose reasonable technologycondition. Further study was required for numerical simulation of the interaction betweenthe electromagnetic field and furnace hearth.