Effect of dry hyperbaric GMAW arc characteristic on welding power control algorithm

Experimental research is carried out by using hyperbaric chamber and welding power source with opening control system. The power source is based on incremental digital PID, which coefficients are set at normal pressure. The electric field intensity of welding arc column is obtained by experiments at ambient pressure of 0.4 MPa, 0.8 MPa and 2 MPa, respectively. The effect of arc charactarasics change on welding power control quality is derived. Based on these results, the ambient pressure, as a variable, is added to the welding power control algorithm. The verification test is conducted at 0.8 MPa ambient pressure using the previous controller coefficients. The results show that the welding current fluctuation is reduced with the improved control algorithm, the stability of welding process is improved with better spatter.