基于动态故障树的加工中心转台可靠性研究

发布时间：2018-03-23 05:14

本文选题：加工中心转台　切入点：动态故障树　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：加工中心转台是加工中心必不可少的功能部件,其可靠性水平的高低对整个加工中心的性能有很大的影响。对加工中心转台可靠性的研究是保障加工中心安全运行和生产的基础,具有重要的理论与应用价值。从第一台加工中心的出现至今,近六十年的发展,加工中心转台的复杂程度变得越来越高,零部件的故障模式也变得多种多样,具有关联关系和动态特性。对具有动态特性的系统进行可靠性分析时,传统方法如可靠性框图、故障树、马尔科夫过程等因无法描述动态失效逻辑因而无法准确建立模型,具有一定的局限性。因此本文提出采用动态故障树方法来分析加工中心转台的可靠性。本文建立了加工中心转台的动态故障树,并根据求解动态故障树的基本方法,模块化后得到静、动态子树。对于静态子树选用二元决策图法对其进行分析;对于动态子树,将其转化为马尔可夫模型再进行定性定量分析。最后,将得到的动态子树与静态子树用合成算法得到整个动态故障树的可靠性指标。并且,以加工中心转台为实例,对其进行基于马尔可夫链的可靠性分析并进行安全评估。然而,对复杂系统而言,用上述提到的马尔可夫模型求解并不方便,因为计算量太大会产生组合爆炸问题,并且马尔科夫方法的使用是有条件的,它要求故障树所有底事件的失效率均服从指数分布。然而,在实际生活中,绝大部分零件的失效率与威布尔分布更相似。基于梯形公式的动态故障树分析方法不限制故障树底事件的失效概率分布,采用近似法的思想,大大减少了计算量,有效地解决了组合爆炸问题。本文就采用这种方法对加工中心转台进行可靠性分析,接着又用蒙特卡洛法对加工中心转台的动态故障树进行了仿真,结果表明,蒙特卡洛法仿真时对底事件的失效概率分布情况没有限制。最后,用FMEA法对加工中心转台进行了故障模式影响分析,根据每个底事件发生的概率、严重度和探测度三者之间的关系计算出风险优先数,并对风险优先数较高的故障模式提出了解决方案与预防措施,提高了加工中心转台的可靠性与安全性。
[Abstract]:The machining center turntable is an essential functional part of the machining center. The reliability level has a great influence on the performance of the whole machining center. The research on the reliability of the turntable of the machining center is the basis to ensure the safe operation and production of the machining center. It has important theoretical and practical value. With the development of the first machining center and the development of nearly sixty years, the complexity of the turntable of machining center has become more and more high, and the fault modes of parts and components have become various. The traditional methods, such as reliability block diagram, fault tree, Markov process and so on, can not describe the dynamic failure logic, so the model can not be built accurately when analyzing the reliability of the system with dynamic characteristics. Therefore, the dynamic fault tree method is proposed to analyze the reliability of machining center turntable. In this paper, the dynamic fault tree of machining center turntable is established, and based on the basic method of solving dynamic fault tree, After modularization, static and dynamic subtrees are obtained. For static subtrees, binary decision graph method is used to analyze them; for dynamic subtrees, it is transformed into Markov model and then qualitative and quantitative analysis is carried out. Finally, The reliability index of the whole dynamic fault tree is obtained by the combination algorithm of the dynamic subtree and the static subtree, and the reliability analysis based on Markov chain is carried out and the safety evaluation is carried out by taking the turntable of machining center as an example. For complex systems, it is not convenient to solve the Markov model mentioned above because the computational complexity is too great to produce the combinatorial explosion problem, and the use of Markov method is conditional. It requires the failure rate of all bottom events in the fault tree to be distributed exponentially. However, in real life, The failure rate of most parts is more similar to that of Weibull distribution. The dynamic fault tree analysis method based on trapezoid formula does not limit the failure probability distribution of the event at the bottom of the fault tree. This method is used to analyze the reliability of machining center turntable, and then the dynamic fault tree of machining center turntable is simulated by Monte Carlo method. The results show that, The Monte Carlo method is used to simulate the failure probability distribution of the bottom event. Finally, the fault mode influence analysis of the turntable of machining center is carried out by using FMEA method. According to the probability of each bottom event, The relationship between severity and detectivity calculates the number of risk priorities, and puts forward solutions and preventive measures for fault modes with higher risk priority, which improves the reliability and safety of the turntable of machining center.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG659

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