| Ti40（Ti-25V-15Cr-0.2Si） is a new type titanium alloy. It will be applied to the key parts of aeroengine such as case. The main characteristics of titanium alloy are low density, high strength and goodburn resistance. The material Ti40is difficult to mechanically machining characterized as serious toolwear, low cutting efficiency and high cost. Electrochemical machining （ECM） becomes the mainmethod of manufacturing hard-to-machine and complex structured aero parts because of mechanicalproperties independence, high material removal rate, no tool wear, and no work piece deformation.However, in the process of electrochemical machining titanium alloy, passivation film is easilyproduced on titanium alloys surface which has low conductivity and results in low surface quality andunstability of electrochemical machining of titanium alloys.In this paper, the effects of electrolyte, process parameters, and electrolyte flow field onelectrochemical machining cavity were mainly investigated. The flow field of electrochemicalmachining cavity was designed. The optimized flow field structure was obtained. The fixtures andtools for electrochemical machining were designed. The experiments of electrochemical machiningburn resistant titanium alloy Ti40for optimization of basic process parameters were carried out andexperiments of electrochemical machining cavity structure were also done. Optimized processparameters were obtained by the orthogonal experiments. Ti40cavity work piece was machined byelectrochemical machining. The details are as follows:（1） The experimental research on basic process parameters of electrochemical machiningtitanium alloy Ti40was carried out. The effect of different electrolytes and process parameters onmachining quality was investigated to get dissolving rule of titanium alloy Ti40. The experimentaldevices for electrochemical machining of plane were designed, such as fixtures and tools. Ti40’smachining characteristics in five types of electrolytes were studied to determine the best electrolytebased on surface quality and removal rate. The contrast of direct and pulse current effect on ECMTi40was made. Surface quality of Ti40work piece was improved using pulse current. Using theoptimized electrolyte, effect of frequency and duty cycle and electrolyte concentration on surfacequality and removal rate of ECM Ti40was studied, and reasonable process parameters were obtained.（2） The research on electrolyte flow field design for electrochemical machining of cavity wasmade. The flow direction was optimized. Four kinds of slot layout structure were designed. The flowfield computational simulation was done. The ‘l’ slot layout is selected by comparing and analyzingflow velocity and flow field uniformity. Moreover, the flow field experiment research on different cathode slot layouts was made. The ‘l’ and ‘Y’ slot layout cathodes were manufactured to do the ECMexperiments of cavity. The results show that the ‘l’ slot layout cathode derives better surface qualityand has better flow field which matches with computational simulation.（3） The experimental research on ECM Ti40cavity was carried out. The experimental devicesfor electrochemical machining of cavity were designed. The four factors orthogonal experiments ofvoltage, inlet pressure, cathode feed rate, electrolyte concentration of ECM cavity were carried out toget optimized parameters. These parameters were used for electrochemical machining Ti40cavity.The work piece was measured. Better cavity quality and faster feed rate were achieved by using theseparameters. Roughness is Ra0.371μm and material removal rate is690mm3/min. |
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