Numerical Simulation Study on Correlation Between Characteristics of Slice Tungsten Electrode Pulsed Arc with Insulating Wall Constrain and Transverse Shrinkage Deformation of Groove in Ultra Narrow Gap

On the basis of Maxwell equations and fluid mechanics equations, a three-dimensional mathematical model of slice tungsten pulsed arc with insulating wall constrain in ultra-narrow gap welding process has been established. By comparing and analyzing the electromagnetic force distribution, temperature field, current density field and flow field of constrain pulsed arc under different groove transverse shrinkage deformation, the change law of characteristics of slice tungsten constrain pulsed arc and mechanism of the influence of groove transverse shrinkage deformation on the arc characteristics be cleared. The results show that the guiding effect of the fore-end of the slice tungsten and the hysteresis of modality of pulse arc to the change of pulse current are the major causes influencing the characteristics of the constrain pulsed arc. The guiding effect makes current of constrain pulsed arc flow to the position with small discharge gap, the peak value of the physical field is generated near the position. The hysteresis of modality of pulse arc to the change of the pulse current will lead to a large difference in the current density distribution at different times, which will change the transmission characteristics of constrain pulsed arc. On the one hand, the transverse shrinkage deformation of the groove will enhance the compression effect of the groove sidewall on the wall of the constrain pulsed arc, resulting in the increase of the current density, cathode jet flow rate, electromagnetic force and arc temperature. On the other hand, it will prompt the arc current density to flow to the sidewall.