Research On Prediction And Control Method Of Machining Deformation Of Aviation Aluminum Alloy Frame Beam Structure

In the field of modern aerospace,integral structural parts are widely used as supporting components.The emergence of integral structural parts effectively reduces the overall quality of the aircraft,increases the stability of the overall structure,saves assembly time and reduces manufacturing costs.However,in the actual processing process,due to the high material removal rate,the complex geometric structure of the workpiece,the large change of the overall structural stiffness and the influence of the multi-feature structure,the overall structural parts are prone to large deformation after forming,which has a negative impact on the assembly performance and service performance of the components.Therefore,it is an important problem to fully understand the deformation causes of the overall structural parts,accurately predict the machining deformation and propose effective deformation control methods.Effective shape control technology is of great significance to improve product quality,improve finished product manufacturing efficiency and save manufacturing economic costs.In this paper,the structural characteristics and processing characteristics of the integral frame beam structural parts are analyzed,and the residual stress redistribution and deformation control methods in the processing process are studied.The specific contents are as follows:1.The machining characteristics of key structure of frame and beam workpiece(corner and thin-wall)are analyzed.By analyzing the cutting contact relationship of different paths,the instantaneous undeformed chip thickness model of cutting process is established,and the instantaneous cutting force prediction model of milling process is established.By analyzing the cutting path and contact relationship of different corner machining types,the prediction model of milling force of corner structure can predict the sudden change of milling force well.Based on the geometric parameters of the tool,the boundary of cutting contact area and the calculation method of instantaneous chip thickness with deformation,to analyze the deflection pattern of thin-wall structure in the milling path.2.A prediction model of cutting residual stress was established based on the stress state of the workpiece surface under thermal mechanical load during cutting.At the same time,the tool wear is brought into the calculation process of residual stress,and the prediction model considering the effect of tool wear on the residual stress of machined surface is established.The accuracy of the model is verified by relevant experiments.Based on the analysis of the machining process of the cavity,the prediction model of the surface residual stress for multiple cutting and the prediction model of the cutting residual stress for thin-walled parts is established.The theoretical and experimental results show that the distribution of residual stress on the machined surface can be effectively improved by multiple cutting processes under the same cutting removal quantity.3.The initial residual stress inside the blank is one of the main factors that induce the machining deformation of the structural parts.Therefore,based on the basic assumptions and experiments of the initial residual stress of the blank,the distribution law of the initial residual stress of the blank is obtained.Then the relationship between the internal stress redistribution of the workpiece and the balance during the material removal process is established.Through the plate bending theory,the relationship between bending resistance and stress change induced by workpiece deformation is analyzed.The delamination method is used to calculate the deformation of the workpiece caused by stress redistribution and rebalancing in the remaining workpiece during material removal.Based on the single cavity machining deformation prediction model,the machining deformation prediction model of stress redistribution of H-section frame beam workpiece is established.Based on the geometric structure characteristics of the workpiece,the time-varying section moment of inertia equation is established to simulate the deformation generated during the material removal process.Finally,the deformation of the workpiece caused by the internal stress rebalancing and the residual stress on the cutting surface is verified by experiments.4.By analyzing the causes of machining deformation of integral structural parts,a method of controlling machining deformation considering comprehensive factors is proposed.Based on the analysis of the machining characteristics of the feature structure,an improved corner machining method is proposed to reduce the sudden change of the corner milling force and reduce the effect of additional load on the workpiece.Aiming at the processing sequence of structural cavity,the influence of multi-processing technology on the machining deformation of workpiece is analyzed.According to the structural characteristics of frame beam workpiece,different clamping methods are designed,and the variation law of stress distribution is analyzed by finite element method.Considering the influence of multiple factors on deformation,a deformation control processing method is proposed.Based on theoretical calculation and experimental analysis,through the processing experiment of typical frame beam workpiece,the processing deformation of the sample is significantly reduced,which proves that the shape control technology proposed in this paper can effectively reduce the deformation of frame beam structural parts.