The Numerical Simulation Of The Influence Of Magnetic Field On Short Circuiting Arc And Droplet Transfer

To control CO2short circuit transition welding spatter at present, research to improveformation of weld, which mainly concentrate on thin plate welding with low current. But thewire diameter will be larger with medium welding current, and the bad phenomenon such asarc blow will be generated. So the external longitudinal magnetic field will be introduced toarc area, and the influence of magnetic acting on the welding arc shape, drop transfer andformation of weld were researched. Then the magnetic field control the CO2welding inmedium welding current has been solved.Combining with numerical simulation, numerical calculation and experimental data wereadopted in this topic. The change of welding arc shape, drop transfer and formation of weldunder the action of magnetic field were simulated by numerical simulation. The influence oflongitudinal magnetic field on CO2welding can be observed visually. Secondly the parameterssuch as the angle of arc, the radius of arc, the droplet shape were computed by high speedcamera. The weld parameters under the action of magnetic field were acquired by flat welding,and the change rule of welding arc shape, drop transfer and formation of weld were explainedby experimental data. At last, be quantizing the influence of magnetic field on CO2weldingwith numerical modeling and calculation formula method. To analysis the stress form ofmolten drop during arc burning phase, the initial stage and final stage of short circuit phase.The reasons for changes of these parameters were explained fundamentally.Through the experiment and numerical analysis results show that, under the effect of lowfrequency magnetic field, at the optimum parameters of the magnetic field2A60Hz, the arcshape is expansion of the bell jar type, the drop transition frequency increases than thatwithout magnetic field. The weld pool width increase and penetration decrease. Under theeffect of high frequency magnetic field, at the optimum parameters of the magnetic field2A2000Hz, the arc is compressed and the drop transition frequency increase, but the weld poolwidth decrease and penetration increase. During arc burning phase and the initial stage of shortcircuit phase, the electromagnetic contraction force on molten drop under action of lowfrequency magnetic field decrease, that promote the drop spreading to molten pool and reduceshort circuit instantaneous splash. During the final stage of short circuit phase, the high frequency magnetic field compressed short circuit liquid bridge, the snap of metal bridge waspromoted, and the short circuit time was decreased, the drop transition frequency wasimproved. Then it reduced the electrical explosion splash and improved the formation of weld.