【作者】 王立涛；

【导师】 程耀东； 柯映林；

【作者基本信息】 浙江大学 ， 机械制造及其自动化， 2003， 博士

【摘要】 由金属切削加工引起的被加工零件整体或局部变形是机械加工中一个普遍性问题，而对于航空航天产品尤为突出。航空航天结构件尺寸大，加工周期长，完成加工后，零件就会发生弯曲、扭曲或弯扭组合的结构变形，使零件难以达到设计要求，甚至成为废品，严重影响着航空航天产品的生产进度与成本。因此，进行切削加工变形机理及相应工艺措施的理论和应用研究具有重大的理论意义和工程应用价值。 本文，首先对引起切削加工变形的主要原因进行了分析，结合生产现场反馈的技术信息，确定以控制零件残余应力作为解决变形问题的突破口。从切削加工产生残余应力规律研究到零件内部原有残余应力因切削加工而重新分布规律的研究，详细分析了航空结构件因铣削加工而引起变形的规律和特点，提出了控制该类零件加工变形的思路和方法。 第二，考虑到本文研究的具体对象是航空结构件，材料多为铝合金，且以铣削加工为主，因此，通过实验研究了给定刀具前提下该种材料的铣削力学特性，建立了铣削力公式。该模型的建立既解决了本论文研究所遇到的实际问题又为相关领域的实验研究工作提供了工具。 第三，从分析铣削加工残余应力分布规律的角度，应用现代弹塑性有限元技术，以模拟实验的方式研究了铣削参数与已加工表面残余应力之间的关系，建立了数学模型，为该种材料铣削加工中表面功能形为和加工变形等研究提供了相应的依据。 第四，在上述研究的基础上，利用三维弹塑性有限元技术系统地分析了铣削力要素下铣削加工中走刀路径对已加工表面残余应力分布状态的影响规律以及铣削加工工序间残余应力的相互影响规律，为优选出较为合理的走刀路径和加工过程中安排去应力工序提供指导。 在有限元模拟中，为了贴切实际加工过程，引进生死单元算法来模拟材料去除过程，通过动态施加载荷步来模拟刀具的运动。模拟过程中，每一载荷步都作用于一个单元，先进行加载运算，再进行卸载运算，然后利用生死单元技术将该单元杀死，随之载荷步作用下一个单元，直至“切除”所有拟去除的材料。通过采用这种技术，模拟结果更符合生产实际，为制定合理的工艺路线提供可靠的技术支持。 最后，通过实例分析并与现场实际零件的变形趋势相比较，对本论文研究结论进浙江大学博士学位论文行了验证，从而说明本论文研究的思路、方法是可行的，研究结果也是可靠的。更多还原

【Abstract】 The whole or local part machining distortion caused by cutting is a common problem in the machining filed, and it is more serious to aeronautic and astronautic products. For the large structure and a long period of time in machining, geometry distortion may be caused, which makes them not satisfy the design aim, sometimes, they maybe turn into waster, so the problem of machining distortion affects the throughput and operating costs of aeronautic and astronautic products seriously. That is, this thesis’s work of the distortion theory as well as the theoretic and applied study for right technics step has greatly academic and engineer’s value.Firstly, the main factor of the machining distortion was analyzed. According to the above results and the technique information appraising from the work place, the key method of solving machining distortion problem was determined by dominating the residual stress in part. By studying the machining residual stress and inherent residual stress in part, the thesis analyzed the law of machining distortion in detail for aeronautic and astronautic field, and advanced some new research methods for improving on machining technology.Secondly, the milling force model was founded for the material of aluminum alloy used in aeronautics, and the mathematics model was deduced for the regression-orthogonal experimental method of four factors and four standards. The models can not only be used in this thesis, but also can be used in similar experimental study for interrelated fields.Thirdly, the mathematics model showing the relationship between machining residual stress and milling parameters was founded by the modern elasto-plastic technique. This model can be applied to studying the quality of machining surface and controlling the part machining distortion.Fourthly, the law of machining route, i.e. tool paths, and working procedure effecting machining residual stress as well as the law of its releasing were analyzed systemically by using three-dimensional Elasto-plastic FEM, which can optimize the tool paths and make the working procedure more rational.In the course of FEM simulation, the birth-death element arithmetic was introduced into simulating material remove, and the kinetic Load-step was used to simulated tools work. While simulating, one load step acted on an element, first, loaded the element and solved, then unloaded the element and solved and killed the element using kill-element technology. And then, the same steps were used for the next element until all elements were "removed". By using this technology, the result of simulation was more precise and accorded with practicality engineering, and so can apply credible sustain in technique to designing reasonable technology route.Finally, the study conclusion in this thesis was validated by compared analysis example’s distortion with the real part distortion. The results from the test examples havedemonstrated the feasibility and veracity of the proposed methods.更多还原