| Aluminum alloy welding technology and the application of arc welding in additive manufacturing are current research hotspots in the field of efficiency manufacturing.To manufacture a component with excellent mechanical properties,a reliable control technology of welding current waveform and more mature welding process are required.Based on designnig the welding power software and hardware system of aluminum alloy,this paper introduced the intelligent control algorithm of ant colony optimization to achieve fast and accurate control of the welding current waveform.Moreover,the aluminum alloy welding current waveform parameters were optimized by the quantitative evaluation and analysis of the welding arc dynamic performances,and the quality control of aluminum alloy additive manufacturing was studied.The thesis mainly completed the following work:(1)The digital arc welding power supply suited for aluminum alloy welding characteristics was studied.And the overall structural scheme of the aluminum alloy power supply system was designed.The main circuit,DSP control circuit,IGBT drive circuit,wire feed circuit,protection circuit and full-bridge inverter circuit were analyzed respectively,and the phase-shift soft switch control technology was used to effectively reduce the switching loss of the inverter.Moreover,the MATLAB/Simulink model was established to analyze the welding power supply system,which verified the reliability of the hardware circuit.(2)The PID optimization control of aluminum alloy double-pulse MIG welding current waveform based on the ant colony algorithm was studied.Then,the problems of conventional PID control of welding current were analyzed,and the ant colony optimization control algorithm was introduced to realize the optimal control of PID parameters.The MATLAB / Simulink model of aluminum alloy double-pulse MIG welding current waveform was established.The simulation and process test results showed that compared with the conventional PID control,the ant colony optimization PID control not only reduced the adjustment time of welding current waveform by half,but also increased the tensile strength of the resulting weld by 16.4%.(3)The welding power source monitoring system and the welding electrical signal wavelet analysis and evaluation system were studied.The human-machine interaction system was designed with the embedded control chip STM32F103C4 as the core.The monitoring terminal platform of the welding power source was designed using Zig Bee communication technology.Then,the welding arc dynamic electric signal analysis system was studied based on wavelet transform.On the basis of wavelet filtering of the electrical signal in welding,the arc dynamic performance was quantitatively analyzed and evaluated according to the welding current probability density,arc welding voltage probability density and welding heat input.(4)The aluminum alloy double-pulse welding process and its application in additive manufacturing were studied by rectangular wave and trapezoidal wave modulation methods,the influence of base current and low-frequency modulation frequency on aluminum alloy welding was studied that the seam tensile performance would be best when the difference of the base value between the strong and weak pulse was 38 A and the low-frequency modulation frequency was 5 Hz.The current waveform parameters optimized for welding were used in the aluminum alloy additive manufacturing,and three sets of tests with the interlayer cooling times of 10 s,50 s,and 90 s were performed.Moreover the forming quality of the specimens by the two waveform modulation were compared.It was shown that increasing the interlayer cooling time was beneficial to the improvement of the mechanical properties of the specimens,and the mechanical properties of the specimens obtained by the trapezoidal wave modulation were better. |
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