Experimental Research On Five Axis Micro Milling Of Micro Integral Impeller

Micro turbine engine has many advantages,such as light weight and high power density,therefore,it is widely used in aviation,aerospace,weapons,biological medicine et.al.Micro integral impeller is the key component of the micro engine,and its surface quality and machining accuracy will have an important influence on the life and performance of micro engine.At present,five axis micro milling is an effective method to realize high efficiency,high quality and high precision machining of micro impeller.But the micro impeller is a typical micro complicated component,which has characteristics of thin walled blade,large blade distortion,large long thick ratio of blade and narrow flow channel.These characteristics will easily lead to the problems of flutter,tool wear,machining deformation,over cutting and collision interference in the process of impeller machining.Therefore,considering the structure features and machining difficulties of micro integral impeller,the method of combining theoretical analysis with experimental research is adopted to study the five axis micro milling method of micro integral impeller.The main research contents are listed as follows:(1)Geometric modeling of micro integral impeller and tool path planning for flow rough machining are studied.The micro integral impeller with a diameter of 10 mm is taken as the object of study,and the geometric modeling is builed by SolidWorks.The tool path planning of machining micro integral impeller is theoretically studied.A mathematical model of tool path generation based on slice method for flow rough machining of impeller is established.And the calculation method of the free-interference tool orientation for flow rough machining of impeller is studied.(2)Experiment of optimization finishing process parameters for micro integral impeller hub and impeller is carried out.Based on the geometric characteristics of micro integral impeller,the influence of process parameters(feed per tooth,path interval and spindle speed)on the surface roughness of impeller hub and blade is investigated by single factor milling experiments.The topography of impeller hub and blade under different process parameters is observed and analyzed.The blade surface is reconstructed by reverse engineering,and the influence of process parameters on the machining error of blade is studied.Finally,the optimum combination of finishing parameters of micro impeller hub and blade is obtained.(3)The micro ball end milling cutter suitability and tool path experiment of blade finish machining of micro integral impeller are researched.A four part cantilever beam model of micro ball end milling cutter is established.The deformation law of micro ball end milling cutter under static force is analyzed,and the influence of the cylinder length and the half cone angle on the deformation of the cutter is studied.According to the geometric characteristics of the micro integral impeller,the length of the shank,the length of the cylinder and the half cone angle of the tool are selected.Based on the optimization of process parameters,the influence of three different finishing tool path on blade surface roughness machining error and topography is investigated by single factor experiment.(4)The micro integral impeller milling experiment is carried out.The machining process of micro integral impeller is planned,including tool diameter choice and determination of the processing route of the micro integral impeller.Based on the CAM software PowerMill,the toolpath of each stage of the micro impeller is generated.The post processing algorithm of five axis NC machine tool with B-C structure is solved,and the toolpath milling simulation of micro impeller is carried out.Through the DMG five axis machining center,a high quality and high precision micro integral impeller with diameter 10 mm is obtained.On this basis,the smaller micro integral impeller machining is explored,and finally a micro integral impeller with diameter 5mm is obtained.