Research On Physical Characteristics And Welding Process Of Twin-Electrode TIG Welding Method

Twin-electrode TIG welding (T-TIG) is a new kind of welding method characterized by two tungsten electrodes insulated from each other in the torch. Between the two electrodes a coupled electric arc is formed and its pressure is much lower than the original TIG arc. T-TIG can increase the welding speed and deposition rates while keeping high quality welds.The study of this article includes two parts: one is to measure the current density of the T-TIG coupled arc and study the mechanism of the coupled arc; the other is to explore the application of the T-TIG in high speed welding of thin plate and high deposition welding of thick plate.The coupled arc shape is obtained by arc photo collecting system. It can be seen that the coupled arc is not simply the superimposition of two TIG arcs. In the same weld current, the varying gradient of arc cross-sectional area, whose figure is less than that of the traditional TIG, decreases as the distance of the two electrodes increases.The current density of the coupled arc is measured by the WNK808b pressure difference sensor. The result of the measurement of the arc static characteristic shows that the peak of current density is lower than the traditional TIG in the same current of single electrode. The current density is elliptical distribution, and the direction of elliptical long axis is same with the welding direction when the distance of the two electrodes, which is propitious to the concentration of energy and the decreasing of weld width.The experiments of high speed welding of thin plate are carried and the T-TIG welding parameters of different thickness plates are confirmed. The welding speed of 1mm low carbon steel can reach 1500mm/min, much higher than the trandition TIG, and the appearance of the weld is also good.It is indicated in the welding with filler metal experiments of 6mm low carbon steel that the T-TIG welding deposition can be as high as 47.87g/min, which improve the efficiency of TIG dramatically. It is also proved that the low pressure of T-TIG coupled arc and the ellipse shape of the arc thermal resource is the reason of high deposition in T-TIG. The experiments above prove that T-TIG has a bright prospect in high efficiency welding.