Research On Key Technology And Processing Optimization Of High Speed Noncircular Piston Turning Control System

Noncircular surface parts are the general term of various mechanical parts with noncircular cross section.As a special and basic part in machinery industry,the demand of noncircular parts has been increasing rapidly in recent years,among which the noncircular mid-convex elliptical piston is the most typical.However,with the increasingly demanding requirements of environmental energy consumption in industry and the increasing complexity of noncircular parts,the production flexibility,accuracy,efficiency and surface processing quality of the parts are also raised to a new height,the traditional processing method has become a bottleneck restricting its development.Therefore,the high speed noncircular turning is an important means of high efficiency machining for noncircular parts,it has important theoretical significance and engineering application value for the research on the key technology and optimization of its control system.Aiming at the related technical problems in practical production,such as the low machining precision and efficiency and low quality of machining surface,the motion state and force model of non-circular turning process are established in this paper,the contour fitting technology and intelligent error optimization of noncircular surface parts,the fast tool servo control strategy for noncircular high-speed turning and the multi-objective optimization of machining parameters for surface roughness and texture feature are studied,the noncircular high-speed turning NC system has been developed.Based on studying the machining principle of noncircular high-speed turning,the mathematical model of track,velocity,acceleration and cutting force of noncircular high-speed turning is established,and the change trend of displacement,velocity,acceleration and force is analyzed according to the model and graphic simulation,which provides the basis for further research on the key technology of noncircular high-speed turning control system.In order to solve the problem of contour fitting technology for noncircular surface parts,this paper describes the contour of the outer circle effectively using grid data points set,puts forward bidirectional interpolation and discrete interpolation of noncircular contours formed by standard and nonstandard curves,and establishes a model based on BP neural network and GA algorithm to optimize fitting resolution.These solve the difficult problems of noncircular contour fitting and error control,and promote the development of noncircular high-speed turning technology towards outline programming and intelligent error control.Aiming at the problem of fast tool servo control in non-circular high-speed turning,the mathematical model of fast tool servo is established and the dynamic characteristics of current loop,velocity loop and position loop in the model are simulated and analyzed.By considering the diversity and complexity of machining conditions such as intermittent cutting of pin holes in actual machining of products,a compound feedforward PID control strategy based on input feedforward and dynamic forward compensation is proposed.After the analysis of the model and experimental processing test,the tracking error is less than 2 ?m,this control strategy can effectively improve the tracking performance and improve the machining accuracy and stability of noncircular surface parts.In view of the fact that the surface quality of noncircular turning is rare but the surface quality is an important evaluation index of turning,the multi-objective optimization research of noncircular high-speed turning for surface roughness and texture features is studied in this paper.By analyzing the influence of key processing parameters on surface quality and taking the variance of grain width as the evaluation index of texture features,an integrated regression model is proposed which includes the improved Beta distributed Cuckoo search algorithm(IBCS)and the multi-objective optimization system of expected function.The experimental results show that the average error of the IBCS prediction results is not more than 15%,which can effectively improve the surface processing quality of the noncircular surface parts.Finally,the integrated noncircular high-speed turning numerical control system is developed and the production application and industrialization popularization are carried out.The product ellipticity of the noncircular high-speed turning CNC system is less than ±7?m,which reaches the advanced level of noncircular turning.