Research On Key Technology Of Vibrating Feed And Pulse Current Electrochemical Machining Of Special-shaped Holes And Grooves

Vibrating feed and pulse current electrochemical machining is a process to remove metal materials,which based on the principle of electrochemical anodic dissolution,combined with the vibrating feed of the tool cathode that controllable vibration superimposed on the numerical control motion,and coupling control of controllable vibration and pulse power supply.In this thesis,the key technology of vibrating feed and pulse current electrochemical machining of special-shaped holes and grooves is studied,aiming at the hole and groove structure in aerospace,chemical fiber machinery and heat exchange equipment.Firstly,the basic technological rules of continuous-feed ECM,vibrating-feed ECM and ECM coupled with pulse and vibration have been expounded,the electrochemical dissolution characteristics of titanium alloy,the forming process of longitudinal section of hole and groove,and the influence of machining accuracy and process stability have been systematically studied.The influence of vibrating feed on the gap distribution,electrolyte conductivity distribution and workpiece material removal is discussed.Moreover,the influence of pulse and vibration coupling control on current density distribution and feed rate of the tool cathode is analyzed,which lays a theoretical foundation for follow-up research.Advanced machining technology is realized by high performance machining system.In order to obtain ideal technical index for fabrication of special-shaped holes and grooves,vibrating feed and pulse cuurent electrochemical machining system has been constructed.An electromagnetic driving vibration system of voice coil motor is developed,and the vibration parameters could be accurately adjusted in the range of technical specifications.A pulse and vibration coupling module is developed to control the turn-on and turn-off of pulse power supply according to the vibration position signal.Moreover,the electrochemical machining control system is developed,which realizes the functions of machining parameters setting,machining process monitoring and multi-system linkage,and the controllability of machining process is improved.Analyses of flow field characteristics and experimental research on vibrating feed and pulse current electrochemical machining of arc-shaped narrow groove array have been carried out.The electrolyte flow pattern,the flow channel geometric structure and the effect of superimposed vibration on the flow field stability in electrochemical machining of arc-shaped narrow groove arrays are discussed.The effects of vibration frequency,amplitude and peak voltage on the average groove width and side-wall slope are analyzed,and the simultaneous fabrication of 135 arc-shaped grooves on the rotating component with good process stability and consistency are realized by using the vibrating-feed ECM mode.Based on the research of electrochemical dissolution characteristics,the slice cathode design and experimental research on vibrating feed and pulse current electrochemical machining for the deep narrow groove of titanium alloy have been carried out.The influences of stiffener distribution on the slice cathode deformation and electrolyte flow velocity are discussed.The influence of different ECM modes on the feed rate and machining accuracy of deep narrow groove machining is analyzed.Moreover,high efficiency machining of deep narrow arc-shaped grooves on TB6 titanium alloy is realized by using the mode of vibrating-feed ECM,and the machining accuracy is close to pulse-vibration coupling ECM mode.Finally,the gas-liquid two-phase flow simulation analysis and technological experiment in the vibrating feed and pulse current electrochemical machining of diamond-shaped holes have been carried out.The distribution of electrolyte velocity and void fraction in the machining gap under the condition of superimposed low-frequency vibration is discussed.The structure optimization design of tool cathode flow channel is carried out based on the simulation analysis of gas-liquid two-phase flow field and the method of interval shrinkage.The effects of different ECM modes on the machining accuracy and the surface quality of diamond-shaped hole are analyzed.Moreover,the high quality machining of diamond-shaped blind holes and through holes is realized by means of pulse and vibration coupled electrochemical machining.The above theoretical analysis and experimental results show that the vibrating feed and pulse current electrochemical machining could obtain better machining effect and better technological adaptability for shaped holes and grooves with different materials,sizes and shapes.It provides a new technical route for machining the film cooling holes in the turbine blade,the grille array in the air inlet of stealth aircraft,and the shaped groove in the fuel nozzle.