【作者】 刘辰；

【导师】 徐家文；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2010， 博士

【摘要】 现代机械产品正朝着集成化、小型化、轻量化、高性能化的方向迅速发展,为达到产品减重、增效、节能、减排、延寿、且更加安全可靠之目的,采用整体构件设计已成为重要技术措施。其中,三元流叶轮、包括三元流闭式叶轮更具上述优点,已开始在航空航天发动机、以及舰艇、核能、采矿、石油化工等领域使用的先进透平机械中得到越来越多的应用。但是,三元流闭式叶轮结构非常复杂、加工可达性差,且有的材料还很难切削,对其整体制造(不是分体制造)又成为当今世界先进制造领域中正在力求解决、但还没有解决好的技术难题。本文针对三元流闭式叶轮上复杂弯扭型腔(叶间流道)的加工难点,提出并实施了组合电加工技术方案,并应用数字化技术,优质、高效、快速响应地解决了三元流闭式叶轮整体加工的工艺难题。首先,论文在已有的典型整体构件组合电加工技术的基础上,提出了适合于复杂三元流道的组合电加工工艺方案;建立了三元流闭式叶轮的数字化模型,分析其结构特点及加工难点,制定了分区域、多电极、多工序的组合电加工工艺路线。其次,论文重点研究了三元流道的数控电解预加工、及随后数控电火花精密加工的组合电加工工艺的若干关键技术,包括三元流道电加工成形规律,加工区域的划分,对应多个近成形工具阴极、电极的设计制造,电解、电火花加工专用工装夹具设计制造,加工工序安排及工序余量分布,工序间数控程序的协调,以及材料电加工特性等,都进行了系统研究并逐一解决。数字化技术是实施组合电加工工艺的技术主线,其核心为数字化建模与加工过程模拟仿真。本文在整个设计和工艺流程中充分利用数字化技术,采用统一的工艺基准和数据传递,在UG软件平台上通过二次开发,建立了统一的数字化仿真模型,实现工具阴极、电极及工装夹具的动态装配,并对电解加工及电火花加工过程进行仿真,从而实现工具阴极、电极以及加工数控轨迹的快速修正,大大提高了工艺设计效率,减少了试验工作量。最后,在以上理论及试验研究的基础上,受工厂委托,试制加工了修理某进口新型压缩机急需的三元流闭式叶轮;通过工艺试验和实际试制加工,对工艺参数选择、夹具安装定位、电极精确对刀、加工结果的数字化检测及数据处理等关键问题进行了分析研究,提出了解决方案;最终试制加工的三元流闭式叶轮经几何测量和工程性能检测,完全符合设计要求,已在工程现场装机使用,至今已正常运转半年多,未出现问题。更多还原

【Abstract】 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.更多还原