Research On Milling And Process Parameters Optimization Of Aviation Al7050 Alloy

Aviation Al7050 alloy has been widely used in aviation manufacturing industry because of its excellent comprehensive properties.It has become the main load-bearing material for fuselage frame,rocket fuel tank,panel,framework of manned aircraft and landing gear support components.Compared with other aviation materials,aluminum alloy structure has the characteristics of thin wall,complex structure,large size and weak rigidity,which make it easy to produce transformation in milling,and then has a great impact on the machining accuracy of parts.Based on the deformation of aluminum alloy structure parts in cutting process,in this article,the mechanical features,milling processing performance,milling transformation mechanism and process parameter optimization of aviation Al7050 alloy were studied by means of experimental study,mechanical modeling and simulation analysis.The main researches are listed as follows:1.To investigate the static and dynamic mechanical features of the aviation Al7050 alloy and construct the Johnson-Cook(JC)constitutive equation.Firstly,based on the static and dynamic compression experiments of the aviation Al7050 alloy,the mechanical features under static and dynamic compression were investigated,and the JC constitutive equation under experimental conditions was constructed by using the least square method.Then,according to Oxley cutting theory,the optimization model of the arguments of the JC constitutive equation was developed.Taking the JC constitutive equation arguments under experimental conditions as initial values,the arguments of JC constitutive equation were prioritized by using GA and orthogonal cutting test data,and the JC constitutive equation suitable for actual cutting was constructed.Finally,the precision and applicability of the model were validated by taking the cutting force as the assessment indicators,which can provide theoretical instruction for the subsequent machining transformation mechanism analysis and machining simulation research.2.In order to study the milling performance of the aviation Al7050 alloy.Firstly,the milling force,machined surface topography,milling temperature and surface roughness were taken as the milling performance studied indicators.Based on the single factor milling test results,the variation trend of each studied indicators with milling parameters were explored,and the optimized JC constitutive equation was validated to be applicable to the milling process.According to the data of orthogonal experiment,the empirical prediction models of milling force,milling temperature and surface roughness were constructed,and the significance of different empirical prediction models was tested and analyzed.3.Research on milling deformation mechanism of aviation Al7050 alloy.Firstly,based on the JC constitutive equation,the three-dimensional milling FEM simulation of aviation Al7050 alloy was carried out.According to the results,the temperature pattern,strain,strain rate and stress field distribution of aviation Al7050 alloy at different speeds were analyzed.Then the orthogonal milling transformation test was set up to investigate the trend of transformation along different measurement directions when milling Al7050 alloy,and the effect of each milling processing parameter and different cooling methods on the transformation.4.In order to meet the requirements of high efficiency and high-quality machining,the machining efficiency and surface quality were taken as the optimization objectives.Then the constraint conditions were set according to the processing requirements,and the milling parameters were optimized to obtain the optimal combination of milling parameters to meet the requirements of rough machining and finish machining.Finally,taking the surface roughness as the evaluation index,the applicability of the optimum parameter combination was validated by milling experiments.