Research On Electrochemical Machining Of Titanium Alloy Blisk And Machine Tool Design

The blisk isone of the important components of new aero-engine.The blisk combines the blades and the disk together.The structure of the engineis simplified.By reducing the number and weight of part,the engine's thrust-weight ratio isincreasingand the friction between groove and the bladesis eliminated.The materials of the blisk are always nickel based super alloys and titanium alloyswhich are hard tomilling.Structure of the bliskis complex and the surface of blade has high precision accuracy,so it has high cost and long cycle.Electrochemical machining(ECM)has obvious advantages to traditional machining technologies,such as without the limitation of metal materials,no electrode wear,high efficiency,no recast layer,no residual stress and micro cracks,etc.So the ECM has becomes an important processing method of aircraft complex parts.This paper studied the precision electrochemical machining(PECM)of new titanium alloy Ti60(Ti–5.6Al–2Zr–4.8Sn–1Mo–0.35Si–0.7Nd)blisk.The characteristics of electrochemical dissolution of titanium alloy Ti60 isstudied.a new type of blisk ECM equipment is developed,and precision electrochemical machiningof Ti60 blisk is realized.The specific contents are as follows:1)The electrochemical dissolution characteristics of high temperature titanium alloy Ti60 were studied.The titanium alloy Ti60 of electrochemical tests were carried out.the main components of the electrolyte were optimized and the main processing parameters were determined by the test results of polarization curves and E-t curves.The ECM characteristics of titanium alloy Ti60 wereanalyzed,and those of titanium alloy Ti40 and TC4 werecompared.According to the influence of different replacement elements and the microstructure on ECM,the characteristics of the titanium alloy Ti60 ECM wasstudied,and the relationship between different surface morphology oftitanium alloy machinedwith current density wasobtained.2)This paper takes the main research of the new system of ECM for blisk,and focuses on the designingof the overall structure of the machine and control system.In order to improvingthe accuracyand stability,twodouble-dimensional motion platform structuresinstalled on hollow columnweredesigned,thenthefreemotionof the cathodes can be achieved.In order to ensure the optimization of feed direction,a tilting rotary tablewas designed.To realize of the coaxial feeding,a dual channel structurewas used for the control system.High precision membrane filtration system and high frequency pulse powerwere used,leading the parameters of the electrolyte and power supplymore precise andimproving the performance of thesystem.Finally,the installation,commissioning and trial operation of the equipment were realized.3)The method of the current control was proposed in the whole process of ECM for blisk profiles.In ECM of blisk profiles,highrepeatedaccuracy is difficult to be obtained.Based on this idea,the current is controlledin the whole processing.With making the current almost consistent in the multiple-processing,the repeatability of the profile precision will be improved.The theory of the current control method was carried out,and the relationship between the tool feeding rate and the current changing was established.Furthermore,the strategy of the current control was attained and the automatic regulating systemof cathode feeding based on the changing current was developed.A series of contrast experiments were carried out for Ti60 titanium alloy blisk.The results showed that the current control method can effectively improve the repeatability accuracy of the surface of the blisk.4)Experiment of the titanium alloyTi60 bliskwas carried out,and the manufacture of blisk was completed.The ECM system for the research was used which is designed in this paper.The temperature,concentration,voltage,frequency,duty cycleand the pressure of the inlet and outlet of the electrolytewere all accurately controlled.Through the test of segment of the blisk and the optimization of cathode,the stability and repeatability of the bliskwere ensured.The titanium alloy Ti60 blisk was machined,and the precision and surface roughness of the blisk were detected.The experimental results show that the above research methods and the equipment can realize the PECM of titanium alloy Ti60 blisk.