Study On Metal Transfer Using Median Waveform Control In Double-wire Pulsed GMAW

Double-wire pulsed gas metal arc welding(GMAW)is one of the main ways to improve welding efficiency.It combines the advantages of high welding efficiency of double wire and stable welding process of pulsed welding.When the metal transfer form of double-wire pulsed GMAW is one drop per pulse(ODPP),metal transfer process is stable,the offset of arc is minor,the surface of the weld is uniform and regular,and there are fish scales.However,it is difficult to quantitatively control the metal transfer,the idea of median waveform control is applied to double-wire pulsed GMAW to enhance the controllability of metal transferDouble-wire pulsed median waveform GMAW combines the advantages of high efficiency of double-wire GMAW and precise control of metal transfer by median pulse,it includes three median waveforms:forward median waveform,middle median waveform and backward median waveform.In this paper,the control strategy of forward median synchronous phase waveform is tested,to achieve ODPP and obtain new process methods and matching process parameters,the influences of the median current and the median time of the double-wire median waveform on metal transfer were studiedFirstly,the overall scheme of this project was put forward on the basis of analyzing the principle of double-wire pulsed GMAW median waveform control.The type of welding power supply system is determined and tandem type welding system is adopted.The topology of the main circuit is determined,and the phase-shifted full bridge soft-switching circuit is adopted.The hardware and software control systems based on STM32 were designed to realize constant current control in welding processIn order to test the stability of welding system,relevant simulation tests were carried out The output of current and voltage under simulated load is analyzed,and the test results show that the stability of the welding system is perfect,the system meets the requirements of welding test.Welding experiments with different median currents were carried out at a fixed median time,and welding experiments with different time of median current were carried out under the condition of fixed median time.High-speed photography platform was built,and the metal transfer in the whole welding process was photographed.Current and voltage waveforms and data of welding process were collected during the test.Combined with metal transfer and the weld,the suitable wire feeding speed and welding speed under different median current and median time were obtained,ODPP mode was finally realized.At the same time,the influence of the median current on the welding process is analyzed when the median time is fixed,and the appropriate range of the median current is determined.The influence of the median time on the welding process is analyzed when the median current is fixed,and the appropriate range of the median time is also determined.