| Modern mechanical products are developing rapidly along the direction of integration, miniaturization, light-weighting and high performance. One major trend is to use integrated component design which generally reduces the weight, emission and energy consumption of products, while increases their working efficiencies, working lifes, securities and reliabilities. With all the above mentioned advantages, 3D-Flow impellers, especially 3D-Flow closed impellers, are being used more frequently in the design of advanced turbomachines, which are widely used in engines of aircraft and rocket, ships, nuclear power industry, mining and petrochemical. However, due to the complexity, poor machining reachability, and the extensive use of hard-to-cut materials, integral production of 3D-Flow closed impellers has become a common technical problem in the design of advanced machines.Here, we developed a novel technique aiming to find a solution for the difficulty of machining complex curved cavities on difficult-to-cut material in the production of 3D-flow closed impellers. By combining electrical machining and digitized manufacturing technology, the technique that we developed has been proved to be a good solution with high quality, high efficiency and quick response for the technical obstacles in the machining of integral 3D-flow closed impellers. Based on existing typical combining electrical machining technology(CEMT) of integrated component, we first proposed a method for the CEMT of complex curved 3D-cavities and developed a digital model of 3D-flow closed impeller. After discussing its structural characteristics, we proposed a multi-part, multi-electrode, multi-step electrical machining technique.This study also focused on several key technologies for the precision work in numerically controlled electrochemical machining (NC-ECM) of the pre-processing and the following numerically controlled electron discharge machining (NC-EDM). The topics in this thesis include but not limited to: the shaping rule of electrical machining, division of the 3D-flow cavity, design and production of cathodes and electrodes for near-profiled tools, design and production of the special fixture for NC-ECM and NC-EDM, arrangement of processing procedures, machining allowance distribution among the processing procedures, NC programs coordination, and material characteristics in electrical machining.Digital technology, focusing on digital modeling and simulation during the process of production, is the main component of CEMT. Digital technology was used throughout the whole design and machining process of this study. By redevelopment on UG software platform using uniform production standards and data transformation, we built up an uniform model for digital simulation, where we have achieved (1) dynamic assembly of cathodes and electrodes and the special fixture; (2) simulation for the process of ECM and EDM; (3) quick correction of cathodes and electrodes and their NC-tracks; (4) greatly improved the efficiency of product design; (5) reduced the amount of testing work.Based on the above theory and experiments, the novel method that we developed was tested on commission as requested by a factory in a task to manufacture the 3D-Flow closed impeller that is urgently needed for repairing an imported new compressor. By conducting preliminary experiments and testing productions, we thoroughly studied the problems related to several key steps during this process, such as parameter determination, fixtures installation and location, the tool-electrode setting accurately, digital tests on the products, and data analysis, and proposed solution for each problem. The testing results from geometric measurement and engineering testing showed that the final 3D-Flow closed impeller product produced in our test trial perfectly meets all the designed requirements. The above mentioned 3D-Flow closed impeller was loaded into a machine in the project site since then and has continuously worked for more than six months without any problem.
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