Study On Machining Deformation And Parameters Optimization For Semi-open Impeller

The impeller is a kind of complicated parts which are widely used in the industrial fields such as petrochemical,aerospace,metallurgy and nuclear power etc.The design and machining accuracy of the impeller will affect the performance of the industrial products.Therefore,it is necessary to study the design and machining accuracy of impeller.This paper focused on semi-open impeller.Use Surface Modeling Methods,Orthogonal Test Method,Finite Element Method,Milling Experiment and Genetic Algorithm Theories were used to research the impeller geometry model,the milling force model,the impeller blade milling elastic deformation prediction and impeller cutting parameters optimization.The concretely works were listed as follow:(1)The matrix form of NURBS curve was derived,which laid the foundation for the control of NURBS curve,simplified the complexity of calculation,and provided convenie-nce for application of the Matlab.(2)The interpolation calculation of the data points which in the shaft disc and cover plate curve were carried out.According to the curve curvature comb the smooth of the shaft disc and cover plate curve were detected.And then bias the shaft disc and cover plate curve along the normal vector direction according to the thickness of the blade.(3)On the basis of the researches,the milling force formula of A1 alloy 7050-T7451 in the milling center of DMU50 was determined combined with the special conditions of this experiment.Based on the four factors and four horizontal orthogonal methods,the influence of milling factor on Fx,Fy and Fz were analyzed.Then the formula of the milling was derived by the least square method.In the end,the milling force formula has been proven to be reliable by the milling test.And the model laid the foundation for the research on the deformation of the milling blade.(4)Based on the milling force formula what was established on the third chapter,using the finite element analysis software ANSYS was used to analysis the deformation of the blades.Therefore it provided some reference data for the compensation of the elastic deformation error of the blade milling.(5)Aiming at the problems of low machining efficiency and high machining cost,the paper constructed the target function of production efficiency and production cost.Finally,Genetic Algorithm was applied to solve the mathematical model to obtain the optimal milling parameters.