【作者】 蒋平；

【导师】 郭波；

【作者基本信息】 国防科学技术大学 ， 管理科学与工程， 2010， 博士

【摘要】 产品的可靠性是设计出来、制造出来、管理出来的。产品在设计阶段确定的可靠性要求需要通过制造过程予以实现和保障,如果在制造过程中不充分考虑各种因素对产品可靠性的影响并加以控制,加工完成后产品的可靠性指标往往达不到设计的要求。因此,在制造过程中保障产品的可靠性是一个必须解决的问题。论文针对制造过程中最常见的机械制造过程开展产品可靠性的保障研究。在当前快速响应制造的需求背景下,制造企业面临研制时间短,技术上的不确定因素,技术改造的滞后,产品可靠性缺乏实践考验,管理缺乏经验等问题。深入研究和解决这些问题,必须要贯彻以可靠性工程为重点,积极开展工艺可靠性研究,强化技术基础、加强管理,实施技术与管理的有机结合,使工艺可靠性工作最终达到保障产品可靠性的目的。因此,论文以此需求为牵引,在总结相关研究的基础上提出了机械制造工艺可靠性的基本概念和分析方法,并建立相应的模型来指导对机械制造过程的有效控制,为机械制造过程保障产品可靠性的最终目标提供技术支持。论文主要在以下几个方面开展了研究:1)机械制造工艺可靠性的概念和评价指标根据分析和控制机械制造过程保障产品可靠性能力的研究需求,论文在系统总结已有研究的基础上,提出了机械制造工艺可靠性的基本概念。为全面评价机械制造的工艺可靠性,提出了实用的评价指标体系,如工艺可靠度、工艺故障发生率、工艺故障平均维修时间、工艺稳定性、工艺自修正性能、工艺遗传性等,并给出了相应的计算方法和选择原则。2)工艺可靠性建模由于产品的可靠性指标是在孔位特征的加工过程中逐渐形成的,所以为了保障产品的可靠性,需要首先确定那些决定产品可靠性指标的关键孔位特征。论文通过Bayes方法整合多个专家的判断,来确定那些影响产品可靠性指标的关键孔位特征。在确定关键孔位特征之后,论文根据关键孔位特征加工过程之间的相互关系以及它们对工艺可靠性的作用,建立了工艺可靠性的各类模型。3)工艺可靠性影响因素的分析和控制由于关键孔位特征的加工过程往往决定了产品固有可靠性水平,因此论文将孔位特征的加工过程作为工艺可靠性的主要影响因素。只有对这些影响因素加强分析和控制才能使机械制造的工艺可靠性达到保障产品可靠性的要求。因此,论文首先提出了关键孔位特征加工过程影响因素的模糊评价方法,然后从产品孔位特征的测量数据分析入手,分别针对多个孔位特征的控制和多工序加工过程的单个孔位特征的控制需求,运用多元统计分析方法来实现分析和控制。为减少加工过程中工艺故障的发生,从而保证工艺可靠性的指标符合要求,论文在充分考虑工艺故障的损失和预防性维修费用的前提下,基于比例故障模型提出了预防性维修的决策方法,能够有效降低机械制造过程的运行费用并保证工艺故障发生率不超过要求的水平。4)工艺可靠性的评定论文将机械制造工艺可靠性的评定分为系统级和指标级。在系统级的工艺可靠性评定中,从保障产品可靠性的效果评价出发,通过试生产的产品可靠性指标与目标值之比来评定工艺可靠性,这就要求准确估计产品的可靠性。但是在产品制造完成交付用户之前,因为受时间或经费的限制,不允许投入大量产品进行可靠性试验或者试验时间很短没有失效数据,难以直接预计产品的可靠性。因此,论文以比较常见的寿命服从威布尔分布的产品为研究对象,提出了在产品可靠性小样本试验零失效的情况下,根据类似产品的可靠性数据和关键孔位特征数据的比较来评定产品可靠性,从而能够较准确地通过其可靠性指标与目标值之比来评定机械制造的工艺可靠性;在指标级的工艺可靠性指标评定中,论文提出结合试生产的数据来评定工艺可靠性指标的方法:基于Bayes融合的工艺故障发生率评定方法和验证工艺故障平均维修时间的序贯验后加权检验方法。论文所提方法与试生产相结合,在小样本条件下能够较准确地验证工艺可靠性指标,从而为及时改进相关工艺和设备提供理论与技术支持。论文从实践需求出发,初步探讨了机械制造工艺可靠性的理论和方法,能够为设计和改进工艺路线、缩短开发周期、生产符合可靠性要求的产品提供有效参考。更多还原

【Abstract】 Product reliability is produced by design, by manufacture and management. The target value of product reliability that was determined in product design stage must be implemented and ensured by manufacturing process, for if the impacts of various factors in manufacturing are underestimated and are out of control, reliability indices of finished products will more likely fall short of requirement. Therefore, ensuring product reliability in manufacturing process becomes an essential problem to be solved. This dissertation focuses its research on ensuring product reliability in mechanical manufacturing process which is most familiar in manufacuting domain.In the context of fast response manufacturing, manufacturing enterprises have to deal with problems such as short developing time, uncertain technical factors, delay of technical reform, short of validation for product reliability, and insufficient management experiences. In order to solve these problems, we should emphasize on the application of reliability engineering, research on process reliability, enhance technical foundation and management, and combine techniques with management. Ensuring product reliability is the research target of process reliability. Therefore, motivated by the requirement, this dissertation summarizes related research, based on which, the concept of mechanical manufacturing process reliability and its analysis methods are proposed. Corresponding models are constructed to instruct effective control of mechanical manufacturing process. The purpose of this dissertation is to provide technical support for ensuring product reliability in mechanical manufacturing process.This dissertation researches on following issues:1) Concept of mechanical manufacturing process reliability and evaluating indicesAccording to the requirement of analysis and control of the capability to ensure product reliability for mechanical manufacturing process, this dissertation summarizes related researches and proposes the concept of mechanical manufacturing process reliability. To completely evaluate mechanical manufacturing process reliability, the dissertation also presents applicable evaluating indices, such as process reliability, frequency of process faults, mean time to repair process fault, process stability, process capability of self-correction, process transmissibility, etc. Corresponding calculating methods for these indices and their selecting principles are also proposed.2) Modeling of mechanical manufacturing process reliabilityAs product reliability indices are gradually shaped during the manufacturing of holes and positions, to ensure product reliability, the key holes and positions, whose manufacturing determine the product reliability indices should be confirmed first. This dissertation synthesizes judgments of experts by means of Bayes theory, to identify the key holes and positions. After the key holes and positions are identified, this dissertation constructs models of process reliability, according to the relations between the machining processes of the key holes and positions and their impacts on process reliability.3) Analysis and control of impacting factors for process reliabilityAs machining processes of key holes and positions usually determine the inherent reliability of product, this dissertation regards the machining processes as main impacting factors for process reliability. Hence, process reliability can ensure product reliability only by enhancing analysis and control of these impacting factors. Therefore, this dissertation first presents a fuzzy method to evaluat factors that affect key holes and positions. Then, based on measure data of product’s holes and positions, it applies multivariate analysis methods to implement analysis and control, according to the control requirements of multiple holes and positions and single hole or position in multiple processes, respectively. In order to reduce the chance of process fault occurrence and hence ensure that indices of process reliability meet requirement, the dissertation takes the loss of process faults and cost of preventive maintenance into accounts, presents a decision approach for preventive maintenance, based on proportional hazards model. The proposed approach can effectively reduce the cost of operation for mechanical manufacturing process and guarantee the frequency of process faults will not exceed requirement.4) Process reliability evaluationThis dissertation classifies evaluation of mechanical manufacturing process reliability as system level and index level. In the system level of process reliability evaluation, from the poitview of evaluating process reliability’s performs on ensuring product reliability, it is implemented by compare the reliability index of manufactured products with target value, which requires precise estimating of product reliability. However, before the products are handed over to customers, the number of products that can be put into reliability test is small or zero failure is obtained when test time is short, due to limts of time or cost. It is hard to estimate product reliability in such situation. Therefore, this dissertation researches on product whose lifetime follows Weibull distribution, which is popular in practice. It presents the method to estimate product reliability by use of reliability data of similar product and comparison of key holes and positions data between the two kinds of products, in the case of zero failure result obtained in product reliability test with small sample size. It can precisely evaluate mechanical manufacturing process reliability by comparing product reliability index with target value. In the index level of process reliability evaluation, this dissertation proposes that process reliability index evaluation should be combined with data from trial manufacturing. It presents an evaluation approach for frequency of process faults based on Bayes fusion method and a sequential posterior odd test method to evaluate mean time to repair process faults. The proposed methods are incorporated with trial manufacturing and hence are capable to precisely evaluate process reliability indices and offer effective support for improving processes and equipments.This dissertation, motivated by manufacturing requirements, explores theory and methods for mechanical manufacturing process reliability and obtains initial research results. It is grateful to provide references for designing and improving process route, shortening developing period and producing products that match the reliability requirements.更多还原