Experimental Investigation Of Electrochemical Machining For Large Size Twisted Blisk Cascade Passage

As a new type of structural component,blisk gradually replaces the traditional structure.The blisk plays a more and more important role in aero engine.Blisk,which combines a rotor disk and blades constructed as a single substance,eliminates the mortise and tenon groove,reduces the number of parts.So the structure is simplified,the weight is reduced,and the reliability is enhanced.Because of high strength,high hardness material,manufacturing process of blisk is facing more and more difficulties.Traditional machining has been difficult to meet the modern requirements of aero engine blisk.Due to its advantages,including high material removal rate,no tool wear,and good surface quality,electrochemical machining(ECM)has become one of the main blisk machining methods.In general,blisk machining with ECM method has two steps in sequence,namely,blisk cascade passage machining and profile shape machining.As the first step,the main purpose is to remove most of material and to process the blade with a certain margin and precision.In this paper,a new method was developed to study the electrochemical machining of large size cascade channels.A series of studies were carried out on the large size twisted blisk cascade passage.The main contents are as follows:(1)Based on the analysis of the complex characteristics of the deep feed and large twist angle,the machining method of rotary feeding electrochemical machining was applied.According to the basic law of ECM,the optimal feed direction was determined.An optimization design method of cathode machining edge curve was presented based on the uniformity of residual.According to the machining feed law,the cathode profile and tool cathode were optimized by optimization design method.(2)Based on the simulation of the special machining position in the whole machining process,the particularity of the flow field of the rotary feeding electrochemical machining was analyzed.The sealing cover and sealing device were designed,which solved the electrolyte sealing problem in the process of tool cathode rotary feeding.The model of special machining position in the whole machining process was established,and the simulation was simulated by software.By analyzing the pressure and flow rate,the inlet pressure of 0.9MPa was determined,which satisfied the need of the flow field of the rotary feeding processing.(3)The experiment was carried out by using the special rotary fixture,the results showed that optimal design of the tool cathode can meet the processing requirements,and guarantee the residual equilibrium.By the experiments of different feed rates,the feeding speed could be increased to 0.6mm/min stably,and then the machining efficiency was improved.The channel margin distribution law was analyzed.The machining edge of the tool cathode was further optimized based on residual uniformity.The complete blade section was processed.The results showed that margin difference of the other parts were uniform in addition to the root of blade.At the root of the blade,margin difference was 2.58 mm and 2.75 mm,and the other place of the blade was 1.92 mm and 2.07 mm.The minimum allowance of the basin and back of blade increased to 2.67 mm and 2.68 mm.The results of the experiment are helpful to realize the subsequent precision ECM of the large size twisted channel.