The Research On Digital Pulsed MIG Welder

Pulsed MIG welding (Pulsed Metal Inert Gas Welding) is concerned by many welding workers at home and abroad for it's pulsed-spray transfer in large current range, good axial, welding in all positions, the heat input is adjustable and the better weld quality. The appearance of the pulsed MIG welding has promoted welding technology's development largely. Traditional pulsed MIG welder can not meet with the requirements of the market for the increasing of the welding productivity, product quality, welding automation and intelligence, and is replacing by the digital pulsed MIG welder step by step. This article designed the digital pulsed MIG welder based on the MCU controlling.First, this article introduced the main circuit structure and working principle of the digital pulsed MIG welder. The main circuit uses a soft switch and full-bridge inverter structure, selectes IGBT as the inverter device, the inverter frequency is 20 KHz. The main circuit is composed of rectified filter circuit, inverter circuit, high-frequency transformer, output rectifier and output filter.Second, this article introduced the control system of the digital pulsed MIG welder, which includes hardware design and software programming. According to the characteristics of MIG welding, the control board is composed of main control board, wire feed board and driver board. The main control board is the heart of the whole control system. The main mission of the MCU 80C196KC is: preset parameters and display, the welding process timing control, give out wire feed signal and drive signal,sample current and voltage signal, A/D conversion, PI control, trouble treatment and so on. This article mainly introduced the software design based on compilation language, program structure, the design of the main program and interrupt program and given out the corresponding program flow chart. The program uses many of the commonly anti-interference measures, such as: watchdog, redundant instruction, digital filter and so on.Finally, debug the designed hardware circuits and software programs, measure the waveforms of the wire feed and driver, and measure the welding pulse waveform with resistance box, all of them achieved the desired goals. Then weld with the different diameter wires (Φ1.0,Φ1.2,Φ1.6) and wire materials (carbon steel, stainless steel, aluminum and aluminum alloy). Given out the weld parameters with the different wire diameters and materials in welding, and analyzed the differences and similarities among them. The main problems were described when the pulsed MIG welder is debugging and welding in this article, and provided reference to improve unified welding in the future.