Study On Numerical Simulation And Experiment Of Milling Process For Aerospace Monolithic Components

The machining distortion of monolithic components is one of the most striking problems in aviation manufacturing industry. It has important value to investigate the effect factors of machining distortion and methods for reducing or avoiding distortion. Based on the domestic and foreign investigated status, from the three dimensional cutting principles, the distortion of thin-walled part, and the key modeling techniques of monolithic components for the simulation, a method combining theoretical analysis with finite element calculation and experiment is adopted in this dissertation to study the distortion prediction.The cutting mechanism has been deeply investigated. Using the three dimensional oblique cutting model, the machined surface residual stress of aluminium alloy 7050T7451 has been simulated. The tool finite element model with helical edge has been used to simulate the milling process of aluminium alloy 7050T7451, and the physical value including cutting force and cutting temperature has been analyzed.Based on the theory of cutting deformation of thin-walled parts, the key techniques of cutting simulation of thin-walled has been studied. The three dimensional finite element model of milling process for thinned-wall part has been established. The part deflection of thinned wall part has been simulated using the established model. The cutting stress, strain, and part deflection have been investigated further. Which provided the conditions for the investigation and control of local deformation.The key modeling techniques of the machining distortion simulation for the milling process of monolithic components have been investigated, which include the simplification of geometrical model, simplification of technics, the original residual stress of raw material, simplification of cutting layer and the application and acquirement of cutting loads. The restart analysis method has been adopted to simulate the milling process of monolithic components. These provide the conditions for the machining distortion simulation of monolithic components.Aiming at the structure and cutting characters of frame parts, the finite element model used to simulate the machining distortion has been established. The key modeling techniques of the machining distortion simulation for the milling process of monolithic components have been investigated, which include the simplification of geometrical model, simplification of technics, the original residual stress of raw material, simplification of cutting layer, the application and acquirement of cutting loads and the restart analysis method . The symmetrical milling method has been adopted in the milling simulation and experiment process of monolithic components with the common milling method.Four technics have been used to investigate the milling distortion of small dimension frame parts in the simulation and experiment. Through the analysis and comparison of results of simulation and experiment, the finite element model has been verified. The results proved that the symmetrical milling method can decrease the milling distortion effectively. The symmetrical milling method has been used to predict and control the milling distortion of practical dimensional aviation frame part.