Research On The Technology Of The Integral Impeller Machining With Barrel Milling Cutter

The integral impeller has the characteristics of non tenon connection,high reliability and good aerodynamic performance.It is widely used in the field of high end turbine machinery,such as aero engine,centrifugal compressor and so on.The five axis NC machining is the main method of the whole impeller manufacturing.Because of the geometric characteristics of the impeller and the limitation of the cutting tool technology,the integral impeller of the aero engine and the whole impeller of the cap disc are used in the milling of ball end cutter,which leads to the long processing cycle and high manufacturing cost of the single impeller.The wide application of the integral impeller parts is limited.Aiming at this problem,this paper studies the NC machining technology of integral impeller barrel milling cutter from the aspects of tool design and process planning.The details are as follows:A customization method of barrel milling cutter considering the constraint of machining conditions is proposed.Through the analysis of the whole impeller milling process,the mathematical model of the design of the contour curve of the drum type milling cutter is established,with the cutting angle of the cutter flank milling,the radius of the blade root,the cutting residual height,the cutting row spacing,and the diameter of the cutter bar not less than the ball end milling cutter.The tool customization program is completed based on the Matlab graphical user interface module,and the tool design parameters can be directly output for the CAM software based on the constraint parameters.According to the model of the typical blisk,the integral impeller of the free-form surface and the integral impeller of the cap disc,the barrel milling cutter is designed with the above program.and the processing technology of the blisk,shaft disc impeller and the cap disc impeller by the barrel milling cutter is made respectively.The number of tool paths is about 70% less than that of ball end milling cutter.The process simulation of the blisk is carried out to verify the rationality of the processing program.The results of the simulation and the design model are compared with the cutting residue and overcutting.The results show that the number of residual cutting and the residual cutting volume of the barrel milling cutter is significantly reduced compared with the ball end cutter.The machining performance of customized cutting tools is tested,and the blisk is machined.The cutting tests are carried out on the typical titanium alloy and hardened stainless steel with a custom drum type milling cutter and ball end cutter,the surface roughness and cutting force in the process are measured.It is proved that the barrel milling cutter has better surface quality than ball end cutter under the same cutting parameters,especially under the same cutting row spacing.When the cutting force analysis can be obtained,the same material,the same cutting parameters and the cutting row spacing are the same,the effective value of cutting force in the cutting tool is same,proving that the cutting tool improvement does not affect the cutting force when the workpiece is processed.Therefore,when barrel milling cutter is processed,it can refer to the speed feed of ball end milling cutter,but adopts larger cutting row spacing.The titanium alloy single vane and aluminum alloy bladed disc assemblies were machined with customized tools.The results show that the surface quality of titanium alloy blade is good,and the surface roughness of impeller is satisfied.Compared with the ball end cutter,the barrel milling cutter has obviously improved the machining efficiency,and the machining process is stable without interference.