Key Technical Research On High-performance Nc Machining Of Thin-walled Shell Parts

With the broad application of thin-walled shell parts in modern military, the NC machining of high performance of thin-walled parts has become an urgent problem. Because their structure is complex, the removal rate of material is high, thin-walled position is plentiful, and the machining accuracy requirement is high, we should not only ensure surface dimension accuracy and surface roughness, the precision of dimension and position of each hole, and the precision of each hole and surface, but also ensure the flatness of surface, mutual position precision. Thin-walled shell parts often cause bending, distortion or bending-tortuous composition deformation in NC machining process, so that it is difficult to meet design requirements and the efficiency is hard to improve because of insufficient rigid property, which has greatly affected the economic efficiency of enterprises. The key technical research on high-performance NC machining of thin-walled shell parts has positive significance in the development of modern manufacturing.Firstly, the paper presents the research background, introduces the main factors of influence on processing quality and efficiency of thin-walled shell parts, summarizes the development of the clamping plans design and residual stress research. Based on this, the paper illustrates the purpose, significance and main work.The paper designs the positioning and clamping scheme based on the positioning and clamping theory, combining with the structure characteristics of thin-walled shell parts. The decision variables, state variables and objective function in the clamping scheme are designed with the theory of optimum, and the mathematical model of clamping optimization of thin-walled shell parts is established. Using the finite element method, the various clamping schemes of thin-walled shell parts are analyzed and chosen. Finally, the optimum method to control the clamping deformation of thin-walled shell parts is obtained, which lays a foundation for NC machining of high performance of thin-walled shell parts.According to the minimum deformation theory of thin-walled shell parts, the special jig is made for a thin-walled part. The finite element method is applied to analyze the role of controlling deformation of the thin-walled shell part and the deformation discipline of the jig, which provides beneficial theory for further controlling the clamping deformation.The initial residual stress of the plank stuff of the thin-walled part is tested and analyzed with the peeling layer theory in order to obtain the stress distribution of the plank stuff. Combined with the optimized processing route, the processing technology of the thin-walled shell part is sketched. Based on the optimum theory, the mathematical model of the machining parameter optimization variables of the thin-walled shell part is established, GA is used to solve the optimization of the model, and the optimal machining parameter combination are get. Through the improvement of the special jig, the quick positioning of the part is realized. The automatic programming software is applied to realize the efficient program. The NC synergistic method of the thin-walled shell part is studied under the above aspects.