Abstract:A process variant of variable polarity plasma arc welding (VPPAW), that is, the pulsed plasma gas VPPAW process, was developed. The pulsed plasma gas was transmitted into the variable polarity plasma arc through a high-frequency solenoid valve to modify the output of the plasma arc. The collection of arc electrical characteristics, arc shapes, and weld formation from VPPAW, double-pulsed VPPAW (DP-VPPAW), and pulsed plasma gas VPPAW (PPG-VPPAW) was carried out to examine if the pulsed plasma gas was able to pl… Show more
“…The stability of the weld pool and keyhole is the prerequisite for obtaining a large penetration and good weld quality [ 2 ]. However, in the PAW process, the dynamic stability of the weld pool and keyhole is poor, and the welding process-parameter window is narrow, which restricts its wider applications in the industry [ 3 , 4 ]. To further improve the weld pool dynamic stability and the keyholing capability in PAW, Wu et al developed a process variant of PAW, i.e., ultrasonic-assisted plasma arc welding (U-PAW) [ 5 ], which exerts ultrasonic vibration on the tungsten electrode, as schematically illustrated in Figure 1 .…”
The acoustic radiation force driving the plasma jet and the ultrasound reflection at the plasma arc-weld pool interface are considered to modify the formulas of gas shear stress and plasma arc pressure on the anode surface in ultrasonic-assisted plasma arc welding (U-PAW). A transient model taking into account the dynamic changes of heat flux, gas shear stress, and arc pressure on the keyhole wall is developed. The keyhole and weld pool behaviors are numerically simulated to predict the heat transfer and fluid flow in the weld pool and dynamic keyhole evolution process. The model is experimentally validated. The simulation results show that the acoustic radiation force increases the plasma arc velocity, and then increases both the plasma arc pressure and the gas shear stress on the keyhole wall, so that the keyholing capability is enhanced in U-PAW.
“…The stability of the weld pool and keyhole is the prerequisite for obtaining a large penetration and good weld quality [ 2 ]. However, in the PAW process, the dynamic stability of the weld pool and keyhole is poor, and the welding process-parameter window is narrow, which restricts its wider applications in the industry [ 3 , 4 ]. To further improve the weld pool dynamic stability and the keyholing capability in PAW, Wu et al developed a process variant of PAW, i.e., ultrasonic-assisted plasma arc welding (U-PAW) [ 5 ], which exerts ultrasonic vibration on the tungsten electrode, as schematically illustrated in Figure 1 .…”
The acoustic radiation force driving the plasma jet and the ultrasound reflection at the plasma arc-weld pool interface are considered to modify the formulas of gas shear stress and plasma arc pressure on the anode surface in ultrasonic-assisted plasma arc welding (U-PAW). A transient model taking into account the dynamic changes of heat flux, gas shear stress, and arc pressure on the keyhole wall is developed. The keyhole and weld pool behaviors are numerically simulated to predict the heat transfer and fluid flow in the weld pool and dynamic keyhole evolution process. The model is experimentally validated. The simulation results show that the acoustic radiation force increases the plasma arc velocity, and then increases both the plasma arc pressure and the gas shear stress on the keyhole wall, so that the keyholing capability is enhanced in U-PAW.
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