The Real-time Decoupling Control For Pulsed MIG Welding Process Of Aluminum Alloy

In recent years, with the wide application of aluminum alloy in automobiles, trains and other means of vehicle, requirements of automation, intelligence and welding quality in aluminum alloy welding become higher. Due to the strong heat accumulation, the weld width will become wider, even collapse at constant welding parameters in pulsed MIG welding process of aluminum alloy. In this paper, how to obtain a perfect weld with uniform pool width and good formation on the basis of ensuring the welding process stable was studied.In this paper, a rapid prototyping control system for pulsed MIG welding of aluminum alloy was bulit using rapid control prototyping technology based on xPC Target. The built control system had fast response and rapid controller development, and control scheme could be adjusted quickly. On this basis, a seamless link between exisiting rapid prototyping control system and vision sensing system designed by LabVIEW was realized through COM technology, which laid a good foundation for control test of pulsed MIG welding.The real-time control for wire extension was carried out based on the rapid prototyping control platform in pulsed MIG welding of aluminum alloy. The control process respectively using arc voltage, ratio of weldig voltage and current(U/I) and vision sensing as feekback signals while using wire feed speed as controlled signal was studied, and different controllers were adopted in the wire extension control test, and stable welding process was obtained.A variable double-pulse control scheme was proposed for pool width control in this paper, and feasibility of the program was proved through process test of variable double-pulse MIG welding. On this basis, pool width control test using the variable double-pulse control scheme was carried out, and weld beads with uniform pool width and good formation were obtained. However, due to single variable control, wire extension had large fluctuation, which showed that multi-variable decoupling control for pulsed MIG welding of aluminum alloy was necessary.Finally, on the basis of pool width control, double-variable decoupling control test with different sensing modes and different controllers was carried out aiming at the strong coupling phenomenon in pulsed MIG welding of aluminum alloy, and good weld formation and stable welding process were both obtained. Therefore, good weld formation could be obtained while the welding process also could be kept stable at the same time through double-variable decoupling control in pulsed MIG welding process of aluminum alloy.