Research On Prediction, Compensation And Experiment For NC Peripheral Milling Deflections Of Thin-Walled Parts

NC milling is a typical machining technics for thin-walled structure workpiece in aeronautic and aerospace industries, especially the high-speed milling being widely used. Due to the low rigidity of the workpiece, deflection errors induced by the cutter and workpiece deflections constitute a common problem that influences significantly the accuracy and the surface quality of the workpiece, even leads to useless products. Consequently, investigation on the prediction and control of the deflection during the milling process of thin-walled workpiece is of great significance to optimize and select appropriate values for the process parameters at the process planning stage. Based on the combination of the finite element numerical simulation technology, cutting mechanics and NC machining technology, the following efforts are focused on the prediction and controlling approaches of the cutting deflection in NC peripheral milling process of thin-walled workpiece. The main works in this thesis can be concluded as the followings:1) The mechanistic model of spiral end milling has been built. A multinomial model of machining parameter is set up based on analyzing the characteristic of milling. Then, milling experiment by means of regression-orthogonal method with four factors is designed to confirm parameters of cutting force model. After this, some experiments have been introduced to validate the model above.2) A thin-walled rectangle plate is simulated to predict and control deflection errors. The deflection errors of the disperse points are used to replace the real form during analysis the deflection errors. Then, a strategy combining cutting location offset with tool axis swing is proposed to plan cutting paths while machining the thin-walled components. Finally, experiments are implemented to verify the reliability of the prediction results and compensation strategies.3) The deflection of five-axis NC milling impeller blade has been analysis using numerical simulation technology, and errors compensation strategy is also proposed. Milling force is calculated by coordinate transformation, and applied to the finite element model. The deflection errors of machined surface have been predicted by finite element analysis. Then, a strategy of modifying the tool axis is illustrated to compensate the deflection errors.In conclusion, the researches in this paper provide an effective error compensation strategy to control the machining deflections in NC peripheral milling process, and provide an effect way to improve the machining quality, reduce the production cost; furthermore, lays a foundation for the further studies on the deflection of thin-walled structure workpieces.