Study On Mechanism And Prediction Analysis Of Machining Distortion For Aero-Multi-Frame Monolithic Structure Parts

It is very difficult to predict the CNC machining distortion of monolithic multi-frame components in aero-industry by either theoretical analysis or experimental research, because of their complicated structure. The machining distortion becomes one of the neck problems in the rapid development and the effecient productin of our national defense weapons. By using finite element simulation and experiments, a deep study is carried out on the mechanism, the prediction method and the variation tendency of the milling distortion. The work in this dissertation can provide a basis for the distortion control of the monolithic multi-frame components.Seven chapters are included in this dissertation, and the main work is as follows.In chapter 1, the background and significance of this research is introduced firstly. Then, the state of the art in the research of machining distortion of the monolithic component is summarized. Finally, the main contents and frame structure of this dissertation are shown.In chapter 2, based on the status analysis on the research of milling force, its characteristic is studied for the aero-material of aluminum alloy 7075-T7351, and the empirical model is established by using the regression-orthogonal experimental method where the factor number is five and the standard number is four. Therefore, a base is provided for studying the effect of milling force on the machining distortion.In chapter 3, according to the milling characteristics of the monolithic multi-frame components, the mechanics basis is discussed. After that, mechanical description and the 3-D modeling rules are given, and the finite element model of the milling distortion of the multi-frame components is established. Finally, the technic route for the research of milling distortion is proposed.In chapter 4, the effect of tool path and clamping schemes on residual stresses as well as machining distortion are analyzed by using three-dimensional elastic-plastic FEM (Finite Element Method). The distortion variation tendency under four typical tool paths, the pressing-plate clamping and stretched fixation is obtained respectively.