| Aluminum is one of the most common light metals,aluminum products are much lighter than stainless steel products with the same volume.Compared with black metal material,aluminum alloy materials have the characteristics of high strength,light weight,small proportion,good corrosion resistance and easy recycling.Recently,Aluminum alloys have widespread application in the automotive industry,machinery manufacturing,aerospace,chemical and shipbuilding industry.However,compared with the ferrous metal material,the aluminum alloy welding process is more difficult,the weld is easier to form pores,slag,welding collapse and welding defects,especially,the weld hole is the most difficult defect to avoid.It is difficulte to weld has been the biggest obstacle to its widespread use.In this paper,to solve the problems,the evaluation method of aluminum alloy welding process,the adaptive fuzzy PID control and the control method of droplet transfer are studied.Based on the precise control of welding current waveform,pulsed MIG welding current modulation mathematical models of aluminum alloy are studied deeply.The simulation model of aluminum alloy pulsed MIG welding power based on Simulink is established,including the main circuit,the control circuit,the pulse current waveform and the PID control modeling,which is proved to be a perfect model.The realtime current and voltage waveforms are filtered by the wavelet packet to solve the interference problem of the electrical signal in the welding process,which can smooth waveform and provides the basis for the subsequent analysis of the stability of the welding process.The adaptive fuzzy PID controller is designed to realize the on-line tuning of PID parameters.The experimental results show that the adaptive fuzzy PID controller is more stable.New methods are designed to solve arc starting and arc ending;the experiment proves that it has certain improvement effect.In order to study the droplet transfer of aluminum alloy pulsed MIG welding,the experimental platform was build to draw the droplet transfer curve of ER4043 aluminum alloy wire with diameter of 1.2mm,which provided reference data for precise control of current waveform.The results show that the backward median phase of the pulsed current waveform is better than that of the non-median phase,a stable welding process and smooth weld can be obtained when the backward median time is 6-10 ms and backward median current is the average value of input current.To improve the stability of the double-pulsed MIG welding of aluminum alloy and enhance the controllability of the input energy of the welding,the fluctuation of the sine wave is analyzed in detail,and a simplified pulsed MIG welding model modulated by sine wave is proposed,which can be applied to the actual welding production.The MIG welding experiment modulated by sine wave with the same positive and negative is engaged on the 3mm aluminum alloy sheet.The experimental results show that the mathematical model can be worked.The welding process is stable with regular droplet transfer,no obvious splash,welding energy can be adjusted by the parameters,weld seams have beautiful ripple appearance.A novel mathematical model of aluminum alloy pulsed MIG welding Gaussian wave modulation is proposed,which make current input be more controllability,a wider applicability,and steady transition.It can be called GAUSS-MIG welding.The waveform characteristics and energy input of GAUSS-MIG welding current are analyzed in detail in the paper.The new welding model is proved to be suitable for the welding of aluminum alloy.Welding experiment using the 2 mm-8 mm aluminum alloy sheet,GAUSS-MIG model welding process is stable,less splash,beautiful weld appearance,the surface of the ripple scale regular and light,arc sound is soft.Backward median current waveform modulated by GAUSS-MIG can easily weld 2mm aluminum alloy.Under the same energy input,compared with the double-pulsed aluminum alloy welding method,welding process of GAUSS-MIG welding model is more stable,the collection of current and voltage signals more neat,weld mechanical properties and microstructure are improved obviously.GAUSS-MIG mathematic model is a novel aluminum alloy pulsed MIG welding method. |
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