糊底机关键部件的优化设计及模态分析

发布时间：2018-07-29 12:32

【摘要】：自主研发的纸纱复合袋糊底机作为一种用于生产水泥袋、食品袋等粉(颗粒)状物品纸纱包装袋的包装机械具有很好的市场前景。依靠经验设计的各个部件的性能是未知的,并且设计方案也无法确保是最优的。随着机械行业和虚拟样机技术的迅猛发展,采用CAD/CAE等现代设计方法来验证和改进设计产品的力学性能已成为机械产品研发设计的主流。本研究为预测和提升自主研发的纸纱复合袋糊底机的力学特性,利用有限元静动态分析技术和现代结构优化技术对糊底机关键部件中的机架和托辊部件进行了静力分析和模态分析,对托辊部件还进行了疲劳分析和优化设计。主要研究内容如下:根据设计图纸和要求建立机架和托辊部件的三维模型,并在有限元软件中完成静力特性研究,验证了机架和托辊部件的结构性能。由分析结果知机架设计合理,满足现场要求。同时托辊部件最薄弱部位摇臂,虽满足强度要求,但应力富裕,有进一步优化空间。以拟合得到结构材料的S-N曲线和疲劳分析理论为基础,采用名义应力法对托辊部件进行疲劳分析。根据分析结果知托辊部件疲劳寿命最薄弱部位位于摇臂上,该结果为托辊部件摇臂的改进优化提供指导和依据。在静力和疲劳分析的基础上,引入灵敏度分析方法确定托辊部件摇臂的优化设计变量,以等效应力小于117.5MPa为约束条件,摇臂质量、疲劳安全系数和等效应力为优化目标建立摇臂优化设计的数学模型。基于DOE(Design of Experiment)试验设计方法建立设计变量与优化目标之间关系的响应面模型,采用多目标优化算法完成了摇臂的优化设计,优化效果显著。并根据优化结果完成试制试验。结果表明优化后的托辊部件力学性能提升显著,满足现场要求。对机架、优化后的托辊部件及摇臂进行有限元模态分析,分别得到机架、托辊部件及摇臂的固有频率和模态振型。由分析结果得,部件的低阶模态频率避开了外界激励源工作频率,不会发生共振现象。但机架的低阶频率较低,易受其他外界影响,为进一步提高其性能,完善设计,根据机架振型结果,为二代糊底机设计提出了参考意见。对摇臂进行了试验模态,得到其固有频率及模态振型,并与有限元模态分析结果作比,验证的了有限元分析方法,进一步为有限元仿真结果的可靠性提供了支撑。
[Abstract]:The paper yarn compound bag paste bottom machine developed by ourselves has a good market prospect as a kind of packing machine used for producing cement bag, food bag and other powder (grain) article paper yarn packing bag. The performance of each component based on empirical design is unknown and the design scheme is not guaranteed to be optimal. With the rapid development of mechanical industry and virtual prototyping technology, using modern design methods such as CAD/CAE to verify and improve the mechanical properties of design products has become the mainstream of mechanical product research and design. The purpose of this study is to predict and improve the mechanical properties of the paper yarn composite bag paste machine. The static analysis and modal analysis of the frame and roller parts in the key parts of the bottom paste machine were carried out by using the finite element static and dynamic analysis technology and the modern structure optimization technology. The fatigue analysis and optimization design of the roller parts were also carried out. The main research contents are as follows: according to the design drawings and requirements, the three-dimensional model of the frame and roller parts is established, and the static characteristics of the frame and the roller parts are studied in the finite element software, which verifies the structural performance of the rack and the roller parts. The results show that the design of the rack is reasonable and meets the requirements of the site. At the same time, the rocker arm of the weakest part of the roller parts meets the strength requirements, but the stress is rich, and there is room for further optimization. On the basis of fitting S-N curve and fatigue analysis theory of structural materials, the nominal stress method is used to analyze the fatigue of roller parts. According to the analysis results, the weakest part of the fatigue life of the roller component is located on the rocker arm, which provides guidance and basis for the improvement and optimization of the rocker arm of the roller component. On the basis of static and fatigue analysis, the sensitivity analysis method is introduced to determine the optimum design variables of rocker arm of roller parts. With the constraint condition of equivalent stress less than 117.5MPa, the rocker arm mass is determined. The optimum design model of rocker arm is established by fatigue safety factor and equivalent stress. Based on the DOE (Design of Experiment) experimental design method, the response surface model of the relationship between the design variables and the optimization objectives is established, and the optimization design of the rocker arm is completed by using the multi-objective optimization algorithm, and the optimization effect is remarkable. According to the optimization results, the trial production test was completed. The results show that the mechanical properties of the optimized roller parts are improved significantly and meet the requirements of the field. The finite element modal analysis of the frame, the optimized roller parts and the rocker arm is carried out, and the natural frequencies and modal modes of the frame, the roller parts and the rocker arm are obtained respectively. The analysis results show that the low-order mode frequency of the component avoids the external excitation source working frequency and does not occur resonance phenomenon. However, the lower frequency of the frame is lower, and it is easy to be affected by other external factors. In order to further improve its performance and perfect the design, according to the results of the vibration model of the frame, the paper puts forward some reference suggestions for the design of the second generation base paste machine. The experimental mode of rocker arm is carried out, and the natural frequency and modal mode are obtained, and compared with the results of finite element modal analysis, the finite element analysis method is verified, which provides further support for the reliability of finite element simulation results.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB486

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