【作者】 吴锐；

【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， 2009， 博士

【摘要】 在新型航空、航天发动机及其它机械产品中,整体结构件的应用越来越多,但是因为结构复杂,且多采用难切削材料,加工难度大、效率低,有的甚至现有技术还不能加工。因此,整体构件的高效、快捷加工技术一直是国际上先进制造技术领域研究的热点之一,也是各个工业大国的核心技术之一。数控电解加工是一项将数控技术与电解加工技术集成的新工艺技术,在整体构件的加工中发挥了独特的作用,越来越多应用于具有复杂型面、异形型腔的整体构件加工。但是,相对于数控切削加工,数控电解加工的工艺准备过程繁琐、周期较长,制约了其快速响应能力的发挥;而相对于拷贝式电解加工,数控电解加工有多种不同的阴极结构和对应的数控运动方案可供选择,而方案的选择又可能对加工效率产生很大的影响。为提高数控电解加工的加工效率和快速响应能力,基于课题组前期相关研究成果,结合整体构件加工的特点,本文对工具阴极和数控运动设计方法,以及不同数控运动方式对加工效率的影响等问题进行了研究,力求缩短工艺准备时间、提高加工效率,实现整体构件的高效、快捷数控电解加工。首先,为缩短工艺准备工作时间,实现快捷加工,针对数控电解加工中阴极设计工作的重点——阴极流场结构设计,研究利用计算流体动力学(Computational Fluid Dynamics,CFD)软件进行加工间隙流场三维仿真分析,实现了计算机辅助阴极流场结构设计。该阴极设计方法应用于某型整体承力环和开式整体叶轮精加工的阴极设计,相对于传统方法,阴极设计和试验修正的总时间缩短约60%。为提高数控电解加工的加工效率,研究了平面阴极和斜面阴极的加工间隙变化规律和加工效率及影响因素,以此为基础提出采用离散化方法分析曲面阴极的加工间隙和加工效率问题,从而有助于在工艺设计阶段优化设计工具阴极及其数控运动方式,实现整体构件的高效数控电解加工。作为上述研究工作的工程应用之一,在开式整体叶轮高效、快捷数控电解精加工研究中,利用CFD软件辅助进行阴极流场设计;以叶片型面等距面的拟合直纹面为依据设计阴极运动轨迹;运用离散法研究叶片扭角对加工间隙变化规律的影响,建立相应的数学模型,进行数控运动设计,并结合工艺试验对设计进行修正。试验加工表明,这是一种高效、快捷的整体叶轮数控电解精加工工艺设计方法。作为上述研究工作的工程应用之二,对结构更复杂、加工难度更大的三元流闭式叶轮数控电解预加工进行了研究。首先,为简化阴极和数控运动设计,缩短工艺准备时间,把叶间流道分为若干区域,使用多个工具阴极分别加工;其次,在用离散法对初始工艺方案加工效率分析的基础上,提出在叶轮毛坯上加工工艺预孔、并进一步改进阴极设计,则相对于不设置工艺孔的加工方案,三元流闭式叶轮数控电解预加工的加工效率可提高约320%,实现了三元流闭式叶轮的高效、快捷数控电解预加工。更多还原

【Abstract】 In new engine of aircraft and rocket, and some key equipment in other industrial fields, integral components have been widely used. Because of the complex structures and hard to cut material features, how to produce those integral components quickly and inexpensively becomes a key problem in the field of advanced machining technology which worldwide researchers are trying to solve, and those high-tech technology becomes a secret in many countries, the know-how about it can not be published. As a new kind of technology, Numerical Controlled Electrochemical Machining (NC-ECM) has some outstanding advantages in machining integral components, especially used for producing some complex integral components. But compared with traditional Electrochemical Machining (ECM), the machining efficiency of NC-ECM is low; on the other hand, compared with NC milling, the preparing time for NC-ECM is long. Both of them restricted the advantages of NC-ECM in produce integral components. In order to shorten the preparing time and raise the machining efficiency, a new designing method of cathode, a new planning method of cathode movement and machining efficiency of NC-ECM have been studied in this dissertation.In order to shorten the designing time for cathode, and reduce the times of trial-and-error, the method of apply Computational Fluid Dynamics (CFD) software to aid designing flow structure of cathode has been studied. The cathode designing method has been successful used for producing integral aircraft shell and opened integral impeller, compared to the existing methods, the time of cathode designing have been reduced by 60%.For the purpose of improving efficiency of NC-ECM, the shaping rule of inter-electrode gap and processs efficiency have been researched. Based on these researches, the shape of inter-electrode gap and the machining efficiency could be analyzed after scatter complex work face into some little planes. In this way, the process of NC-ECM could be optimized, and improve the surface quality and machining efficiency of NC-ECM.As an applied object of above researches, in order to improve the production efficiency of NC precision electrochemical machining opened integral impeller, the methods of cathode designing and NC movement designing have been researched. These incloud the CFD software aided design cathode, design movement trajectory according to the rule surface of offset surface of vane,and developed a mathematical model to design velocities of NC movement. Finally, a test piece of opened integral impeller were produced, the results show that the time of technological designing have been shortened.As another applied object, the high efficiency and rapid respone technologies of NC-ECM in combined electrical machining 3D-flow closed integral impeller have been researched. Because the complex vane surface, narrow and twist channel, 3D-flow closed integral impeller are difficult for machining, we dispart the channel into many parts, than machining those parts with many cathodes, in this way, the designing about profile and movement of cathodes could be simplified. In order to raising the machining efficiency, some craft hole have been drilled in work piece before NC-ECM, and correct the profile of cathode based on analysis of machining efficiency, both of these increased the machining efficiency more than about 320%. In the end, a formal 3D-flow closed integral impeller has been produced, the results show that these technologies could improve the machining efficiency and reduce the prepare time of NC-ECM in combined electrical machining 3D-flow closed integral impeller.更多还原