| The distortion of monolithic component due to CNC machining is one of the most striking problems that aviation manufacturing technologies have to face up to, and seriously hinders the process of the aviation industry. So, it has great value in academic and engineering area to realize the prediction and manipulation of monolithic component machining distortion. The research of monolithic component involves many disciplines, such as mechanical manufacture, solid mechanics, finite element method and etc. In view of the complex nature of problem, a method combining experiment with theoretical modeling and computer analysis is proposed in this dissertation. Then, beginning with the metal cutting principle, two finite element models are constructed, one is a coupled thermo-mechanical finite element model with regard to plain strain orthogonal metal cutting and the other is a three-dimensional finite element model used to simulate milling process. Furthermore, these two models are used to study on the mechanism of milling distortion, the theory of restraining distortion and the process measure.Firstly, the background and significance of this dissertation are elaborated. Then, the current situation of CNC machining of aerospace monolithic component at home and abroad is summarized, and the main factors resulting in machining distortion are analyzed deeply. Furthermore, funded by the subject of national nature science fund and national defense model engineering, the research objective and technical route of this dissertation are advanced, and its research contents and overall structure are listed.In chapter 2, based on metal cutting principle, a coupled thermo-mechanical finite element model is constructed with regard to plain strain orthogonal metal cutting. In addition, several special finite element techniques, such as the chip separation criteria and friction model, have been implemented to improve the accuracy and efficiency of the finite element simulation. A chip separation criterion based on stress failure and geometry is proposed to realize separation of twin nodes. Then, simulating process of metal cutting is discussed. Afterwards, the above finite element model is proved to be right by comparing experiment data with simulation results.In chapter 3, an optimum method of milling parameter based on orthogonal cutting finite element model is proposed. According to mechanics analysis for milling process, a FEM for milling simulation is established. Then, some basic physical parameters, such as stress, strain, temperature and etc, are analyzed and discussed. After that, both residual stress of finished surface caused by milling process and optimization of milling tool rake and milling parameter are researched by simulation.In accordance with M.C.Shaw's idea that chip could be regard as a series of parallel orthogonal slices, a computing model of cutting force and cutting temperature based on orthogonal cutting simulation results is constructed in chapter 4, and a map is established between the three-dimensional cutting process and planar orthogonal cutting process. Thismethod can be used to solve cutting force and cutting temperature of oblique angle cutting process, and provide input parameters for further simulation of 3D cutting process.So as to reveal the reason to bring in distortion due to milling and control it further, an elastic-plastic finite element model is established to simulate the aircraft integrated-components milling process in chapter 5. Some key techniques, including material model, initial residual stress model, dynamic cutting load model and material removal model, are explored and researched deeply. After that, a new flowchart for simulating the milling process is proposed.In chapter 6, the machining distortion law of part caused by release of initial residual stresses and multi-factors coupling are researched. Comparing the result of multi-factors coupling simulation to experiment, the FEA model is proved to be right and can be used to predict distortion of aircraft integrated-part due to milling...
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