Study On Some Problems Of Basic Theory, Experiments And Integrated Technology Of Thin-walled Components In Numerical Control Peripheral Milling

Thin-walled components are widely used in the field of aeronautic and aerospace industry, mechanical engineering industry and civil engineering industry, etc. Advanced manufacturing technologies of various important components involve key technologies for military use and important civil use, which are locked as national privacy in every country. For this case our country has fallen behind those west manufacturing power countries. Due to the characteristic of poor rigidity and some due to complex non-developed surface shape, it is tremendous difficult to ensure thin-walled components machining accuracy using the traditional machining craft techniques. So, surrounding the demand of high machining quality and high machining efficiency of thin-walled components, it has great academic and engineering values for developing the numerical control fundamental research and application.Based on a survey of domestic and foreign research status, by combining theoretical analysis, FEM and machining experiment study methods, and taking peripheral milling process with a thin-walled rectangular plate and an impeller blade as the subject studied, the integrated research on mechanics and NC basic theory, FEM simulations and cutting experiments for thin-walled components peripheral milling are developed in this dissertation. The research achievements are summarized as the following:1. By means of transformation from a moveable loading problem to a fixed loading problem, the thin-walled cantilever rectangular plate symmetrical and nonsymmetrical bending models, flexibility testing functions have been proposed. Thus proximative theoretical solutions are obtained. The corresponding results are good in agreement with FEM simulation results and experimental results.2. The mechanistic model of spiral end milling has been built. A multinomial model between milling force coefficients and quantities in cutting is set up. The milling experiment by means of regression-orthogonal method with four factors is designed to confirm constants of cutting force model. The work is the perfect basis for deflection prediction and error control and analysis.3. An interpolation algorithm for Non Uniform Rational B-Spline(NURBS) curves to control redundancy errors is proposed. A feedrate factor is introduced to improve errors redundancy by properly raising feedrate when the instantaneous curvature was too small, and the machining efficiency is increased. Experimental results demonstrate the combinative capability of the proposed algorithm for compatibility controling machining quality and efficiency. Testing results show that the proposed algorithm is highly effective and correct.4. Post processing algorithms are deduced for five-axis CNC machines with the titling milling head and with the angle milling head. The correctness and effectiveness of the proposed post processing algorithms is verified by means of a cutting experiment. Tool path optimization algorithms are developed for flank milling undevelopable ruled surfaces. Experimental results show that the proposed algorithms can improve machining accuracy greatly in peripherial milling undevelopable surfaces.5. FEM models for predicting machining deflections are established for single axis side milling a thin-walled rectangle plate and five-axis peripheral milling an impeller blade, respectively. The errors compensation strategies of optimizing tool paths are also proposed to control machining deflections. Testing results show that the models for predicting machining deflections are reliable and the strategies for compensating deflection errors are effective.The related theoretical achievements of this paper provide the theoretical guidance for prediction of machining deflections and optimization of tool paths for thin walled components. And some have been realized practical application.