| The diffuser is one of the core components of the compressor.As a typical integral component,it greatly simplifies the structure of the compressor and reduces the weight of the engine,as well as significantly improves the overall performance of the engine.However,they are difficult to be manufactured because of complicated structures,thin blades,large degree of distortion,high distribution density of the blades,difficult-to-cut materials and so on.Electrochemical machining(ECM)has become one of the key technologies for manufacturing diffusers as a result of no tool wear,low-processing costs in mass production,and ignorance of the mechanical properties of materials.In this paper,the blade diffuser is taken as the research object,and the electrochemical machining technology with bidirectional cathodic feeding for the diffuser blade is studied.The specific contents are as follows:(1)A optimization method of cathode feed direction for the diffuser blade electrochemical machining was established.Two factors are considered: one is the angle ? between the cathode feed direction and the normal direction of the blade profile,and the other is the distance between the cathode side and the diffuser hub in the feed direction.By comprehensively considering two factors,the sum of the weighted values of the respective evaluation targets is used as the objective function of the comprehensive optimization.And then,the genetic algorithm is used to optimize the optimal solution to minimize the objective function.The optimal solution can ensure a small angle ? between the cathode feed direction and the normal direction of the blade profile,and at the same time,the distance between the cathode side and the hub is uniform.The hub is prevented from being overcut.Subsequent test results demonstrate the rationality of the optimization method of cathode feed direction.(2)A partially-blocking anti-"W" flow field was designed.The flow field simulation was used to compare the advantages and disadvantages of the lateral flow field and the anti-"W" flow field.There is leakage near the blade leading/trail because the diffuser blade is abnormally long and narrow,the surface of the hub is curved and the blade is twisted to a large degree.A partially-blocking anti-"W" flow field was finally designed to solve the leakage problem and ensure the high-speed flow of the electrolyte in the processing zone.The test results show that the flow field is stable and reliable,and meets the needs of electrolytic processing of the diffuser blades.(3)Cathode profiles were designed based on the method of (8? assisted with computer programming techniques.The current efficiency curve of the diffuser material in the electrochemical machining is measured by experiments at first.The initial profile of the cathode is designed from the three-dimensional shape by replacing ?? with the measured curve in the method of (8?.Then,the machined blade profiles which used the initial cathode was detected and the modification method of cathode profile was introduced.(4)According to the flow field situation,the fixtures were designed to carry out the experimental research on the electrochemical machining of the diffuser blades.With the optimized optimal cathode feed direction and the partially-blocking anti-"W" type flow field,the electrochemical machining test of diffuser blade was carried out in the profile electrochemical machining system.The process parameters,such as electrolyte parameters,voltage,the cathode feed rate are controlled during the processing.The diffuser blades were processed,and the test results proved the rationality of the research. |
PDF Full Text Request