The Research Of Arc Length Control Technology For Gas Metal Arc Welding

Gas Metal Arc Welding(GMAW) is an advanced welding method with many advantages, such as high efficiency, low cost, saving energy, environmental protection, realizing automation easily and so on. So it shows a powerful advantage in the fierce market competition. In the GMAW process, the arc length's variability will lead to change the welding parameters, even break the stability of the welding process. The short arc will frequently produce short circuits and cause bad fusion or welding spatter. On the contrary, it will create weld porosity and poor formation. Therefore, the control of the stability of the arc length is meaningful for the welding quality and productivity.An investigation was made to the GMAW system process, and further for the control purpose a dynamic system and a control mode were designed according to the characteristics of the GMAW systems. By means of the feedback linearization procedure of differential geometry, an equivalent, fully controllable and linear mathematical mode was derived via a homeomorphisms transformation, which makes the complicated nonlinear control problem transformed into a simple linear control problem. And then a Simple Adaptive Control(SAC) algorithm was applied in the GMAW system. So the arc can quickly be adjusted with the outside interference.A digital control system based on DSP was developed and the hardware and software configurations of the GMAW control system were completed. The simulation results in the platform Matlab showed the effectiveness of the proposed controller. The algorithm is satisfied with exact control of welding arc length and the strong robustness for the system variations and disturbances.