国外高档加工中心自动换刀系统的可靠性研究

发布时间：2019-03-13 14:39

【摘要】：伴随着机械设备的功能水平及自动化程度提高,机床发生故障的可能性越来越大,可靠性问题已严重制约了数控机床的发展。加工中心关键功能部件作为机床的重要组成部分,其可靠性水平的高低直接影响着整机的可靠性水平,如换刀系统、电气系统以及主轴等,这些关键功能部件一旦发生故障,将直接影响着整个加工中心的加工效率以及用户的经济效益。自动换刀系统是高档加工中心的一个重要组成部分,是体现高档加工中心性能的重要部分。尽管国产自动换刀系统能够基本满足功能要求,然而其可靠性水平无法与国外先进产品相比,这严重制约了国产数控机床产业的发展。因此,如果自动换刀系统的可靠性得到提升,将有助于国产高档数控加工中心的可靠性水平的提升。国内学者在整机的可靠性研究方面,已经有了一定的理论基础。由于国内机床企业出于短期投资回报率的目的,国内学者无法做到对自动换刀系统进行多年的跟踪实验,无法获得可靠充足的故障数据,这就限制了它的可靠性相关研究。并且专门针对自动换刀系统可靠性建模研究的文献相对较少。另外,对它的研究并不全面,存在很多不足之处。所以,对自动换刀系统的可靠性研究是有必要的。这样可以有助于缩短自动换刀系统的可靠性增长周期,为产品可靠性改进设计及故障诊断维修提供了理论参考。同时在工程中,对于类似产品的相关研究也有很大的参考价值。本文基于现场跟踪试验下采集得到的故障数据,应用故障总时间法对多组不同类型的数据进行了预处理,这样可以为后续可靠性分析提供一个比较准确的数据依据；应用经验建模理论,并选用三参数威布尔分布模型,引入最小二乘法、右逼近法、K-S检验,分别建立基于整机故障间隔时间的可靠性模型、基于自动换刀系统故障间隔时间的可靠性模型、基于自动换刀系统首次故障时间的可靠性模型,这样可以得到更精确的可靠性模型；并结合以上三种模型,应用点估计法,分别得到整机的平均故障间隔时间,自动换刀系统的平均故障间隔时间和平均首次故障时间；应用改进的危害度法分别分析整机和自动换刀系统的故障模式,这样可以得到更合理的实验结果；应用Bayes后验概率模型,建立自动换刀系统与整机的后验概率模型；应用灰色关联分析,建立自动换刀系统与其他系统间的内在联系。
[Abstract]:With the improvement of the function level and automation degree of mechanical equipment, the possibility of machine tool failure is increasing, and the reliability problem has seriously restricted the development of CNC machine tool. As an important part of the machine tool, the reliability level of the key functional parts of machining center directly affects the reliability level of the whole machine, such as the tool changing system, the electrical system and the spindle, etc. Once these key functional components fail, It will directly affect the machining efficiency of the whole machining center as well as the economic benefits of the users. Automatic tool-changing system is an important part of high-grade machining center, and it is an important part of the performance of high-grade machining center. Although the automatic tool-changing system made in China can basically meet the functional requirements, its reliability level can not be compared with the advanced products abroad, which seriously restricts the development of the domestic CNC machine tool industry. Therefore, if the reliability of automatic tool-changing system is improved, it will be helpful to improve the reliability level of domestic high-grade NC machining center. Domestic scholars in the reliability of the whole machine, has a certain theoretical basis. For the purpose of short-term return on investment in domestic machine tool enterprises, domestic scholars can not carry out tracking experiments on automatic tool-changing system for many years, and can not obtain reliable and sufficient fault data, which limits its reliability-related research. And there are relatively few literatures on reliability modeling of automatic tool-changing system. In addition, the research on it is not comprehensive, there are many shortcomings. Therefore, it is necessary to study the reliability of automatic tool changing system. This can help to shorten the reliability growth period of automatic tool changing system and provide theoretical reference for product reliability improvement design and fault diagnosis and maintenance. At the same time, in engineering, there is great reference value for the related research of similar products. Based on the fault data collected under the field tracking test, this paper uses the fault total time method to pre-process many groups of different types of data, so as to provide a more accurate data basis for the subsequent reliability analysis. Based on the empirical modeling theory and the three-parameter Weibull distribution model, the reliability models based on the fault interval time of the whole machine are established by introducing the least square method, the right approximation method and the KS test, respectively. Based on the reliability model of the fault interval time of the automatic tool changing system and the first failure time of the automatic tool changing system, a more accurate reliability model can be obtained. Combined with the above three models, the mean fault interval time, the average fault interval time and the average first fault time of the automatic tool changing system are obtained by using the point estimation method. The improved hazard method is used to analyze the fault modes of the whole machine and the automatic tool-changing system respectively, so that more reasonable experimental results can be obtained, and the posterior probability model of the automatic tool-changing system and the whole machine is established by using the Bayes posterior probability model. The relationship between automatic tool changing system and other systems is established by grey relational analysis.
【学位授予单位】：延边大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG659

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