Research On Short Circuiting Transfer Arc Characteristics Under The Action Of Magnetic Fields

Carbon dioxide welding is a welding method with low cost and high efficiency, and it widely used in the actual production. But it also has the disadvantages of big spatters and bad formation of weld in carbon dioxide welding. Additional magnetic field is a kind of effective way to control spatters and improve bead formation. It can not only control arc shape and the movement process, but also affect the morphology, size and transition frequency of droplet. It has characteristics of simple additional device, low cost, high efficiency and less energy consumption and so on. Because of the particularity of short circuiting arc, magnetic field parameters and welding process parameters optimization study is very rough at present. The effect of magnetic field on welding process has not formed a complete theoretical system, so it has important practical application value that the research of short circuiting arc characteristics in the magnetic field.In this paper, we take the change of morphology of the short circuiting transfer arc under longitudinal magnetic field by high speed camera. We test arc radial pressure distribution under the different magnetic field parameters condition by pressure transmitter and arc current density radial distribution under the different magnetic field parameters condition by tungsten electrode probe. The test results show: With the increase of the magnetic induction, arc morphology gradually transforms from cone shape (or fan) to the bell shape. Without magnetic field and arc pressure performs that center pressure gradually decreases. When the magnetic induction reaches 50mT, arc central pressure appears negative value, which is -40 Pa. It forms bimodal distribution on the whole image. In addition, when the magnetic induction reaches 30mT, the arc central pressure gradually reduces with the increase of excitation frequency. Arc center pressure under the exchange pulse magnetic fields is smaller than it is under the DC magnetic field but the increased peak of radius of gyration improves. Arc current density also performs that the center current density gradually decreased. It forms bimodal distribution when magnetic induction strength reaches 30mT.The change of arc shape under magnetic field was taken by high speed camera. The effect of characteristics of short circuiting transfer arc and droplet transition in the magnetic field was analyzed by the distribution of arc characteristic test. The results show that electric arc was rotated and the shape of arc was changed from cone to bell. It obviously improved arc stability and droplet transition frequency contrast to the non-magnetic field.