大型铝构件高速高效加工中心设计与轻量化研究

发布时间：2019-05-30 00:37

【摘要】：在轨道交通、公路客车、厢式货车等领域,采用全铝结构制造车体成为实现轻量化的一种必然趋势。随着大型整体空心复杂薄壁型材挤压技术及焊接技术的成熟,大型铝构件得到了广泛的推广与应用。近年来,我国高速列车技术得到了飞速发展,但在车体加工制造领域却存在着短板,机加工所用的大型装备仍然主要依赖于进口。针对于大型铝构件特点和加工工艺特点的国产加工中心研究相对落后,加工效率低下、高速驱动及动态稳定性等问题解决不彻底,在高速列车加工制造领域国产设备往往只用于辅助工序,这大大增加了车体加工的成本,降低国产高速列车在世界上的竞争力。因此研究开发具有自主知识产权的、适用于铝合金车体及其大型铝构件的加工机床具有重要意义。本课题研究的加工中心是根据动车车体及大型铝构件结构特点、工艺特点,在继承传统金属切削龙门加工中心基本特点的基础上创新设计而成。对关键部件进行了轻量化设计,提高快移速度,同时通过拓扑优化设计提高了横梁的静动态特性,解决高速运行带来的动态稳定性问题。根据加工中心的设计要求,采用模块化设计基本原理和功能分析法实现机床的总体方案设计,一次装夹可实现铣、钻、镗、扩、铰及锯切等加工。基于模块化设计的分离式立柱可快速更换,便于调整加工中心的Z向行程,同时降低了装配难度。对X/Y/Z向的直线驱动系统进行了设计,介绍了双电机伺服消隙系统的基本工作原理。对原始的横梁方案进行了静动态特性分析,并对关键结合面进行了建模。立柱的螺栓结合面采用虚拟材料模型,通过计算获取了虚拟材料层的弹性模量、泊松比和密度；导轨结合面采用弹簧阻尼单元模型,获取了弹簧单元的刚度系数。在有限元建模过程引入了结合面的参数,分别研究了受重力和切削力的工况下,刀头沿Z向的位移变形情况,并分析了横梁的前6阶固有频率。基于拓扑优化方法对横梁结构进行轻量化设计,提高横梁的动态性能,降低高速运行产生的振动。在Hypermesh中建立横梁及其组件的有限元模型并设置优化目标函数、约束函数以及边界条件。基于最大刚度设计的拓扑优化模型和特征值问题的结构动力学拓扑优化模型,对初始的横梁结构进行了改进,提高了整体刚性和固有频率,同时实现了横梁的轻量化设计。本课题得到2012年山东省科技发展计划(项目编号：2012GGE27113)资助。
[Abstract]:In the fields of rail transit, highway passenger cars, van trucks and so on, the manufacture of car bodies with all-aluminum structure has become an inevitable trend to achieve lightweight. With the maturity of extrusion technology and welding technology of large integral hollow and complex thin-wall profiles, large aluminum components have been widely popularized and applied. In recent years, high-speed train technology in China has been developed rapidly, but there are shortcomings in the field of car body processing and manufacturing, and the large-scale equipment used in machining still mainly depends on imports. In view of the characteristics of large aluminum components and processing technology, the research of domestic machining center is relatively backward, the machining efficiency is low, and the problems of high speed drive and dynamic stability are not solved completely. In the field of high-speed train processing, domestic equipment is often only used in auxiliary processes, which greatly increases the cost of car body processing and reduces the competitiveness of domestic high-speed trains in the world. Therefore, it is of great significance to research and develop machine tools with independent intellectual property rights, which are suitable for aluminum alloy car body and its large aluminum components. According to the structural and technological characteristics of the car body and large aluminum components, the machining center studied in this paper is designed on the basis of inheriting the basic characteristics of the traditional metal cutting gantry machining center. The lightweight design of the key components is carried out to improve the fast moving speed. At the same time, the static and dynamic characteristics of the beam are improved by topology optimization design, and the dynamic stability problem caused by high speed operation is solved. According to the design requirements of the machining center, the basic principle of modular design and functional analysis method are used to realize the overall scheme design of the machine tool. The milling, drilling, boring, expansion, hinge and sawing can be realized by one clamping. The separated column based on modular design can be replaced quickly, which is convenient to adjust the Z-direction stroke of the machining center and reduce the assembly difficulty at the same time. The linear drive system in X/Y/Z direction is designed, and the basic working principle of double motor servo gap elimination system is introduced. The static and dynamic characteristics of the original beam scheme are analyzed, and the key joint is modeled. The elastic modulus, Poisson's ratio and density of the virtual material layer are obtained by calculating the bolt joint surface of the column, and the stiffness coefficient of the spring element is obtained by using the spring damping element model on the guide rail joint surface. In the finite element modeling process, the parameters of the joint surface are introduced, and the displacement and deformation of the cutter head along the Z direction under the conditions of gravity and cutting force are studied respectively, and the natural frequencies of the first six orders of the crossbeam are analyzed. Based on the topology optimization method, the light weight design of the beam structure is carried out to improve the dynamic performance of the beam and reduce the vibration caused by high speed operation. The finite element model of beam and its components is established in Hypermesh, and the optimization objective function, constraint function and boundary condition are set up. Based on the topological optimization model of maximum stiffness design and the structural dynamic topological optimization model of eigenvalue problem, the initial beam structure is improved, the overall rigidity and natural frequency are improved, and the lightweight design of crossbeam is realized at the same time. This project is supported by Shandong Science and Technology Development Plan 2012 (Project No.: 2012GGE27113).
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TG659

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