Studies On U-I Mode Pulse MAG Welding (Fundamental Studies On Two-Wire MAG)

With the development of the world's economy, how to improve the productivity of weld was one of the most important problems of the relevant enterprises. Two-wire MIG/MAG is a new welding technology to improve welding efficiency, its characteristics including high travel speed, high deposition rates and low line energy, etc. Many countries have done some research work on it, but in our country study about it is very few. The equipment of this technology is very expensive in foreign counties.,and it isn't beneficial to its spreading in our country. The paper is to make fundamental study of two-wire MIG/MAG welding system, inquire into the theory of two-wire MIG/MAG, study the stability of U-I pulse used in two-wire welding and build the two-wire MIG/MAG welding system.First of all, the related theories were analyzed and on these bases the two-wire MIG/MAG welding scheme was designed. From the point of arc and droplet transfer , the characteristics of pulse GMAW used in two-wire was analyzed. From the point of weld pool, two-wire welding can resolve the questions resulted from improving the welding speed of traditional welding. If the parameter was unproper, the welding process was unstable because of the arc's disturb each other. So we could take shift phase pulse to reduce the degree of arc's disturbance. The power source was the main part in total design scheme, and traditional I-I pulse welding mode was unfit for two-wire welding because of its output characteristics. So U-I pulse mode was adopted, and pulse control scheme was designed.Secondly, based on total designed scheme, we designed main circuit whose core is inverter, and control circuit whose core is testing and controlling of MCU and PWM. In control circuit, it includs driving circuit, protection circuit, board circuit, timing circuit of feeder and Two-MCU correspond circuit. And the function of reference signal of output current and voltage, time order control, etc was realized through software of MCU.Finally, waveform of current and voltage was tested, output characterise ofpower source we needed was got by adjusting parameters and good dynamic respondence characteristic was got. We found out by single wire welding test. Two-wire welding system was built and shift phase pulse current was realized. And some advices was given to the two-wire welding.In brief, this paper developed U-I pulse welding power source used for two-wire MIG/MAG welding, and found out relationship between droplet transfer and power source parameters in U-I pulse welding process, then built two-wire welding system.