基于动态特性分析的机床结合部建模及结构的改进设计

发布时间：2018-04-25 00:18

本文选题：结合部建模 + 动刚度　；参考：《北京交通大学》2017年硕士论文

【摘要】：机床的发展水平和技术标准直接反映了一个国家制造业的发展趋势,也是国家工业化方面综合国力的评价标准之一。建立机床准确的动力学模型是研究机床动态加工特性和结构优化设计的前提和基础。机床整机的动力学特性在很大程度上都要受到机床内各个部位螺栓结合部的影响,而螺栓结合部的建模又是难点问题,研究者大多将精力放在了机床的整机建模方面,忽略了对结合部处建模方法的研究,对相关问题的研究也不够深入。因此探究机床螺栓结合部处的建模方法和结合部处参数识别方法具有重要的工程意义和理论价值。本文主要研究了含有螺栓结合部的机床动力学模型的建模,主要包括螺栓结合部的建模过程和结合部处参数求解的过程,并对已建立好的动力学模型进行了结构的优化设计与分析。具体内容如下:首先,设计了简单的螺栓结合部试验试件,并得到实物模型以此来研究建模方法和参数识别方法。确定采用弹簧单元来建立结合部模型的方法,以弹簧单元均匀分布为基础探究了弹簧单元圆周分布的建模方法,经对比分析最终确定了圆周分布建模方法的弹簧单元个数和等效直径的大小。采用有限元仿真分析与模态试验相结合的方法对试验试件的螺栓结合部模型中弹簧单元的刚度进行了参数识别,并通过改变预紧力矩的方式验证了该识别方法的正确性。其次,根据吉村允孝思想,将结合部的建模方法和刚度识别方法应用到结合部平均接触面压相等的机床床身地脚结合部的动力学模型中,识别出了地脚结合部处的动刚度值。然后对含有地脚结合部的机床进行试验模态分析,对比仿真结果和实验结果证明了误差在允许范围内,即证明该方法的建模和刚度识别是有效的。最终确立了含有地脚结合部的机床动力学建模方案。最后,运用有限元分析仿真方法,对机床的床身进行了动力学性能的分析,确定其薄弱环节为内部肋板,然后运用ANSYS Workbench中的结构优化设计模块,通过对床身中肋板尺寸和位置的分析,完成了床身结构的设计优化,提高了整体的动力学特性,减轻了床身的质量,节约了生产成本。该方法可以推广到机床其他部件的结构优化设计中,从而为机床结构的改进和优化设计提供了重要方法和依据。
[Abstract]:The development level and technical standard of machine tools directly reflect the development trend of a country's manufacturing industry, and are also one of the evaluation standards of national comprehensive national strength in industrialization. Establishing accurate dynamic model of machine tool is the premise and foundation of studying dynamic machining characteristics and structural optimization design of machine tool. To a great extent, the dynamic characteristics of the machine tool are affected by the bolt joint in each part of the machine tool, and the modeling of the bolt joint part is a difficult problem. Researchers mostly focus on the modeling of the machine tool. The research on the modeling method of the junction is neglected, and the research on the related problems is not deep enough. Therefore, it is of great engineering significance and theoretical value to explore the modeling method and parameter identification method of machine tool bolt joint. In this paper, the modeling of machine tool dynamic model with bolt joint is studied, which includes the modeling process of bolt joint and the process of solving the parameters of the joint. The structural optimization design and analysis of the established dynamic model are also carried out. The main contents are as follows: firstly, a simple bolted joint test specimen is designed, and the physical model is obtained to study the modeling method and parameter identification method. The method of establishing the joint model by spring element is determined. Based on the uniform distribution of spring element, the modeling method of circular distribution of spring element is explored. Finally, the number of spring elements and the size of equivalent diameter of the circular distribution modeling method are determined by comparison and analysis. The stiffness of the spring element in the bolt joint model of the test specimen is identified by the method of finite element simulation and modal test, and the correctness of the identification method is verified by changing the preload moment. Secondly, according to the thought of Yoshimura Yunxiao, the modeling method and stiffness identification method of the joint part are applied to the dynamic model of the joint of the machine bed with equal average contact surface pressure, and the dynamic stiffness value of the joint part of the ground foot is identified. Then the experimental modal analysis of the machine tool with the joint of the ground foot is carried out. The simulation results and the experimental results show that the error is within the allowable range, that is to say, the modeling and stiffness identification of the method is effective. Finally, the dynamic modeling scheme of machine tool with the joint of ground foot is established. Finally, the finite element analysis and simulation method is used to analyze the dynamic performance of the machine bed, and the weak link is determined to be the internal rib plate, and then the structural optimization design module of ANSYS Workbench is used. Through the analysis of the size and position of the rib plate in the middle of the bed, the design and optimization of the bed structure is completed, the dynamic characteristics of the whole body are improved, the quality of the bed is reduced and the production cost is saved. This method can be extended to the structural optimization design of other parts of machine tools, thus providing an important method and basis for structural improvement and optimization design of machine tools.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG502.3

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