【作者】 王晓峰；

【导师】 申桂香；

【作者基本信息】 吉林大学 ， 工业工程， 2012， 博士

【摘要】 数控装备是装备制造业的“工作母机”，是先进制造技术的核心载体，它一方面保障了现代化工业和国防工业的发展，另一方面也成为战略性新兴产业的切入点。是否拥有高性能和高质量的数控装备，已经成为体现一个国家工业化程度和综合实力的标志。近年来随着中国数控装备市场不断扩大，外资企业不断抢滩中国市场，在日趋激烈的市场竞争面前国产数控机床的发展面临巨大压力和严峻挑战。在严酷的市场竞争中如何保证数控机床长时间在高性能、高精度和高效率下正常运行，即提高数控机床本身的可信性水平，已经成为国内外市场竞争的焦点。可信性既是产品质量的核心又是产品质量的重要体现，目前在国内市场上众多机床生产厂商争夺的焦点仍然是可信性水平，可以说机床市场竞争的根本是可信性的竞争。因此本文在国家自然基金课题“基于全寿命周期的数控机床可用性影响度耦合模型及分析技术”的基础上，以国产加工中心为研究对象，根据可信性现场实验数据建立了加工中心整机可靠性模型、维修性模型、可用性模型；建立了加工中心各子系统可靠性模型、维修性模型、可用性模型；对加工中心子系统的可信性影响度进行分析；最后进行了加工中心可靠性增长研究。本文主要研究内容如下：加工中心整机可信性建模。可信性研究需要以大量的现场数据为基础，本文结合课题，通过对15台某系列加工中心进行现场试验，采用定时截尾试验方案获得大量现场实验数据，对所得到的故障数据应用Johnson法进行处理。在进行整机可靠性建模过程中，对以最小二乘法为核心的一元线性回归分析的拟合方向问题首次进行分析，对于x拟合方向和y拟合方向分别经过统计特性分析和蒙特卡洛模拟分析之后，根据所得结论选择合适的拟合方向后对整机可靠性模型进行参数估计，在此基础上应用差分进化算法，以相关系数为目标函数，通过在Matlab中编程对三参数威布尔分布的位置参数进行优化，最后对整机可靠性进行评价。在进行整机维修性建模过程中，在对维修性模型分布类型进行判断之后采用极大似然估计进行参数估计，在建立起两参数的对数正态分布模型后进行维修性评价。在进行整机可用性建模过程中，采用序贯仿真与蒙特卡洛模拟相结合的算法进行可用性的耦合仿真分析，这种方法既体现了序贯仿真的系统状态随时间变化的思想又体现了蒙特卡洛模拟中随机抽样的思想，有效的将可靠性和维修性耦合在可用性之中。根据仿真结果得到整机的瞬时可用度曲线和数学模型。通过整机可信性建模与评价研究，为加工中心整机可靠性、维修性、可用性建模技术提出了更为准确有效的新方法，对该型号加工中心整机可信性模型参数有了准确的估计。加工中心子系统可信性建模。在子系统建模过程中，由于各子系统的现场试验故障数据较少，针对大样本的普通建模方法很难得到正确的评估结果。因此，对于子系统可靠性模型，本文采用基于Bayes理论的小样本威布尔分布建模方法，并应用差分进化算法对相关系数优化，从而得到威布尔分布的参数估计值。对于子系统维修性模型，不但分布于每个子系统的维修数据较少而且关于子系统的维修性先验信息也较少，针对这种情况本文采用一种无需先验信息的对数正态分布小样本建模方法建立了各子系统维修性模型。对于子系统可用性模型，将各子系统视为串联系统前提下，采用基于序贯仿真思想的蒙特卡洛模拟方法进行仿真，根据仿真结果建立各子系统可用性模型。子系统可信性模型的建立，为识别整机中的关键子系统、进一步分析子系统影响度奠定基础。加工中心子系统可信性影响度分析。以往的影响度研究都是在假设系统为不可修系统的前提下进行的可靠性影响度研究，但实际上加工中心是一个典型的可修系统，针对这种可修系统本文首次采用Natvig影响度对加工中心子系统分别进行了可靠性影响度、维修性影响度、可用性影响度分析，根据影响度分析结果找到对整机可信性影响最为严重的几个子系统。为研究所得各子系统影响度值的精确程度以及影响度值的误差范围，在基于序贯仿真思想的蒙特卡洛模拟方法下，对各个子系统的可靠性影响度、维修性影响度、可用性影响度值分别进行了区间估计并且得到了相应影响度的双侧置信区间和单侧置信下限，区间估计结果验证了所得影响度值的合理性。子系统可信性影响度的研究为有针对性提出加工中心可信性增长措施奠定了基础。进一步的为促进加工中心新产品可信性提高提供了依据。加工中心可靠性增长研究。对主轴箱、刀库、电气系统这三个影响度最大的关键子系统进行了故障模式分析和故障原因分析。在对这三个关键子系统进行危害度模糊分析时，由于加工中心是典型的机电一体化产品，其故障模式复杂多样，故障原因、故障现象与故障机理间不但存在着随机性而且存在模糊性等十分复杂的不确定性关系，也就是说在危害度分析时存在很大的模糊性。因此本文在进行危害度模糊分析时，将三角-区间型Type-2模糊隶属函数引入危害度模糊分析当中，很好的体现了隶属度函数本身的不确定性使隶属度函数更加准确。在此基础上以区间数的形式表示各因素的隶属度，这样保证了隶属度函数的所有信息不会丢失，而后进行区间数模糊综合评判。对于危害度模糊分析所得区间数结果采用基于TOPSIS思想的区间数排序方法进行排序，最后找到高危害度的故障模式。根据故障分析与危害度分析结果，侧重于主轴箱、刀库、电气系统这三个关键子系统提出了加工中心可靠性设计改进措施，制造装配过程的可靠性保证措施，关键配套件、外购件的可靠性保证措施。本文在对加工中心整机可靠性模型和维修性模型进行研究之后，采用模拟仿真的方法将可靠性与维修性耦合在可用性当中从而建立起整机可用性模型。针对加工中心子系统故障数据较少的情况，采用小样本方法对各子系统可靠性模型、维修性模型、可用性模型进行研究使所得子系统模型更加真实合理。根据所得子系统模型采用Natvig影响度对子系统可靠性、维修性、可用性影响度计算并进行区间估计，结果表明对整机影响程度较大的子系统为：主轴箱、刀库、电气系统。对这三个关键子系统进行了故障分析与危害度模糊分析，分析结果表明：刀库失调、主轴失调、电气系统元器件损坏等故障模式危害度等级较高。最后侧重于主轴箱、刀库、电气系统对该型号加工中心提出了可靠性设计改进措施，制造装配过程的可靠性保证措施，关键配套件、外购件的可靠性保证措施。更多还原

【Abstract】 CNC equipments are the “machine tools” of equipment manufacture, important carriersof advanced manufacturing technology. On the one hand, CNC equipments preserve thedevelopment of modern industrial and defense industrys; On the other hand, CNCequipments have also become the entry point of strategic emerging industries. Whether acountry has high performance and high quality CNC equipments, it has become the sign ofdegree of industrialization and comprehensive strength for a country. In recent years, withthe expansion of CNC equipment market, foreign invested enterprises keep grabing the shareof the market. The development of domestic CNC machine tools facing enormous pressureand stern challenges, because the increasingly fierce competition in marketplace.In the harsh market competition, how can we keep the high performance, high precisionand high efficiency of CNC machine tools in a long time, in other words raise thecreditability level of CNC machine tools, this has become the focus of competition ofdomestic and international market. Creditability is both the core for the quality of productand an important manifestation of the quality of product. The focus of competition for thedomestic market is also the creditability level for numerous machine tool manufacturers.Fundamental of the competition for machine tool market is the competition of the credibility.This article relies on the National Natural Science Foundation of China "The coupling modelof availability influence and analysis techniques for CNC machine tools based on life cycle ",taking domestic machining center as the research object, bases on a large number ofcredibility field data, studies on: the reliability model, maintenance model and availabilitymodel of whole machining center were established; the reliability model, maintainabilitymodel and availability model of subsystem were established; influences of subsystems ofmachining center were analyzed. At last the reliability growth measures for machining centerwere studied.The studies of this paper are as follows:The credibility modeling and evaluation for whole machining center. The research ofcredibility need base on a large number of field data, this article combined with subject,15machining centers of a series were field tested. A large number of field test data were got,adopting censored time test program. The failure data was processed using Johnson method.In the whole machine reliability modeling process, the problem of fitting the direction for thelinear regression analysis to least squares method as the core was analyzed for the first time. x fitting direction and y fitting direction were analyzed for statistical properties and MonteCarlo simulation. The parameters of whole machine reliability model were estimated afterselecting the appropriate fitting direction according to the conclusions. Location parameterof three-parameter weibull distribution was optimized, using differential evolution algorithm,taking related coefficient as objective function, programming in Matlab. Finally, reliabilityevaluation of whole machine was given. In the whole machine maintainability modelingprocess, parameters were estimated, using maximum likelihood estimates after deciding thedistribution type of maintainability model. Maintainability evaluation of whole machine wasgiven after establishing the two-parameter lognormal distribution model. In the wholemachine availability modeling process, coupling simulation analysis of the availability wasdone, using the method of combining sequential simulation and Monte Carlo simulation.This method not only reflect the idea that system state changes over time in sequentialsimulation, but also reflect the idea of random sampling in Monte Carlo simulation. Thismethod could combine reliability and maintainability into availability effectively. A moreaccurate and effective new method of reliability, maintainability and availability modelingtechnique for whole machining center, the accurate evaluation of credibility level of wholemachine was given, by credibility modeling and evaluation for whole machining center.The credibility modeling for subsystem of machining center. In the subsystem modelingprocess, there is less field test failure data, it is difficult to get the accurate results by generalmodeling approach of large sample. Therefore for the reliability models of subsystems, smallsample weibull distribution modeling method based on Bayes theory was adopted. Objectivefunction was optimized by differential evolution algorithm, thus estimation of weibulldistribution parameters were gotten. For the maintainability models of subsystems, not onlydid each subsystem has less maintenance data, but the priori information in maintainabilityof subsystem was less. In view of this situation, maintainability models of each subsystemwere established by lognormal distribution modeling approach of the small sample withoutpriori information. The availability models of subsystems were simulated, using the methodof combining sequential simulation and Monte Carlo simulation, regarding subsystems asseries system. According to the simulation results, the availability model of each subsystemwas established. The credibility model for subsystem was foundations of identifying keysubsystem in whole machine and further analysis influence of subsystem.The creditability influence analysis of subsystem machining center. In the past, thereliability influence research was on the condition that the system was non-repairable system,but actually machining center is a typical repairable system. For the first time this paper studied reliability influence, maintainability influence and availability influence forsubsystem, using Natvig influence that apply to repairable system. Based on influenceanalysis result, the subsystems which affect credibility of machining center most seriouslywere found out. In order to research on the accuracy of influence and give error range.one-sided confidence limits and two-sided confidence intervals for reliability influence,maintainability influence and availability influence were obtained, using the method ofcombining sequential simulation and Monte Carlo simulation. The result of intervalestimation verified that influence degrees are rational. Influence of subsystem research laythe foundation for targeted failure analysis and further proposing credibility growthmeasures, provide basis that improve the credibility of new product of machining center.Reliability growth of machining center. The three key subsystem of spindle box, toolmagazine and electrical system failure analysis included failure mode analysis and failurecause analysis. When do the criticality fuzzy analysis of the three key subsystems,machining center is a typical electromechanical integration product, failure modes arediverse, the relationship between failure cause, failure phenomenon and failure mechanism isnot only random but fuzzy and some complex uncertain, in other words there is manyfuzziness in criticality analysis. When fuzzy critical analysis is done in this paper, weintroduce triangle-interval type-2fuzzy membership function into fuzzy critical analysis.The triangle-interval type-2fuzzy membership function reflect the uncertainty of themembership function and make the membership more accurate. On this basis the eachfactor’s degree of membership was expressed in the form of interval numbers, so that all theinformation of membership function was preserved. The result was gotten using fuzzycomprehensive evaluation of interval numbers at last. The interval numbers result of fuzzycritical analysis were prioritized, using interval number sorting method that base on TOPSISidea. Finally, found out the failure modes of high criticality. According to failure analysisresult and criticality analysis result, for spindle box, tool magazine and electrical system,propose reliability design improvement, reliability assurance measures in manufacturingassembly process, reliability assurance measures of key corollary parts and purchased parts.In this paper, after studying the reliability model and maintainability model ofmachining center, the simulation method is used of reliability and maintainability ofcoupling in availability,in order to establish the whole machine availability model. For theless failure data of machining center subsystem, the subsystem model could be more realisticand reasonable, using a small sample to research the reliability model, maintainability modeland availability model of each subsystem. According to subsystem model, calculate and interval estimate the reliability influence, maintainability influence and usability influenceby Natvig influence, and the results show that the larger influence subsystem for machine:the spindle box, tool magazine, electrical system. After the three key subsystems failureanalysis and criticality fuzzy analysis, the results show that: tool magazine disorder, spindledisorder, components damage have the higher influence for the whole machine. Finally,focus on the spindle box, tool magazine, electrical system, we put forward reliability designimprovement, reliability assurance measures in manufacturing assembly process, reliabilityassurance measures of key corollary parts and purchased parts.更多还原