| Thin-walled parts are widely used in production and life due to their outstanding advantages such as light weight,high specific strength and compact structure.However,during the production and processing of such parts,the amount of material removal is large,the overall rigidity is poor,it is easy to deform,and the manufacturing is very difficult.In this paper,TC4 titanium alloy integral impeller,which is a typical difficult to machine material with complex thin-walled curved surface,is taken as the research object.The influence of cutting parameters on milling force and surface quality is deeply analyzed by combining experimental research with finite element simulation analysis.The processing deformation law of impeller blade is studied,and the optimal selection of cutting parameters is discussed,so as to provide reference for the production and processing of this kind of parts.The main contents and conclusions of this paper are as follows:Firstly,the orthogonal experiment of TC4 titanium alloy NC milling was designed,and the range analysis and variance analysis of the experimental data were carried out to obtain the influence and significance of different milling parameters on milling force and surface roughness.The empirical prediction model of milling force and surface roughness was established by using the least square method,and the rationality of the regression model was verified.The results show that: in the aspect of milling force,the influence of milling depth and feed rate per tooth is highly significant,milling width has a certain influence,but the influence of milling speed is not obvious;in the aspect of surface roughness,the influence of feed rate per tooth and milling speed is significant,but milling depth and milling width have a certain influence;the established regression equation has a good significance.Then,the structural characteristics and technological difficulties of TC4 titanium alloy integral impeller are deeply analyzed,and the parametric modeling of semi open integral impeller is realized in SolidWorks environment.Through the research on the establishment of blade local coordinate system,load calculation and loading,tool path setting and selection,the finite element analysis model of impeller blade milling is established,and the machining process of blade is studied The law of shape.The results show that the deformation of the blade mainly occurs at the analysis point 5-15,the maximum deformation is located at the edge of the inlet edge,the minimum deformation is located at the middle of the blade near the outlet edge,and the total deformation of the blade from the suction surface to the pressure surface is small.Finally,according to the Pareto optimal solution set theory,the multi-objective optimization model of TC4 titanium alloy milling is established with machining efficiency and surface roughness as the objective function,and the optimal milling parameters selection scheme is solved based on NSGA-Ⅱalgorithm.The results show that the principle of"high milling speed,low feed per tooth,large radial depth"should be followed in the milling process of TC4 titanium alloy,and the axial depth can be selected according to the processing requirements. |
