Research And Optimization Of Laser Welding Technology For Aerospace Power Electronics

Aerospace power electronic products generally use thin-walled high-silicon aluminum alloy materials as the shell,and complete the packaging of the shell through the laser welding process.In the process of laser welding of the casing,it is easy to cause the phenomenon of excessively high temperature inside the casing,which may cause the failure of electronic components inside the casing.In the process of laser welding,the local stress of the shell is also prone to occur,which will cause micro cracks in the shell and affect the welding quality.Therefore,it is of great significance to study the laser welding process of high-silicon aluminum alloy thin-walled shells.The thesis establishes a three-dimensional solid model of high-silicon aluminum alloy thin-walled shell,and then generates a finite element model through meshing,and defines the initial conditions and boundary conditions of laser welding.The material performance parameters of the cover plate and the shell under high temperature conditions are calculated by JMatpro software.The pyrogen model for simulating laser welding is studied and determined,and the main parameters of the heat source model are given.With reference to a research institute's actual welding process parameters for such thin-walled shells,the paper gives four different laser welding sequences,and simulates the laser welding process based on these four different welding sequences on the shell model,and obtains The temperature field and stress field under different welding sequences are shown.Through comparative analysis,an optimal welding sequence is selected.Based on the determination of the optimal welding sequence,the influence of laser welding process parameters such as welding speed,welding power,welding interval the,etc.on the shell temperature field and the shape of the molten pool was studied using single factor analysis.A three-factor three-level orthogonal test plan was designed,and these three process parameters were optimized to obtain a set of welding process parameters that can achieve the best molten pool shape.Under the welding process parameters,the maximum temperature of the shell sidewall and the maximum stress on the shell surface also meet the technical requirements.In view of the high temperature at the four corners of the shell model during laser welding,the structure of the four corners of the shell model was optimized based on the original shell model.Given a chamfering radius and different chamfering depths,the new shell model was re-simulated by laser welding simulation.It was found that when the chamfering depth is 3 mm,the temperature at the corner of the shell and the surface stress of the shell can be effectively reduced.According to the optimized laser welding process parameters and the optimized shell model,a real laser welding experiment was carried out,and the welding effect was good after testing.The thesis takes the temperature and stress of the shell as the constraints and the optimal shape of the molten pool as the goal.The best laser welding process plan is obtained by simulation.The actual laser welding experiment proves the correctness of the research content The research content of the thesis provides new ideas for laser welding process optimization.