Reliability Analysis of Electrical System of CNC Machine Tool Based on Dynamic Fault Tree Analysis Method

The electrical system of CNC machine tool is very complex which involves many uncertain factors and dynamic stochastic characteristics when failure occurs.Therefore,the traditional system reliability analysis method,fault tree analysis(FTA)method,based on static logic and static failure mechanism is no longer applicable for dynamic systems reliability analysis.Dynamic fault tree(DFT)analysis method can solve this problem effectively.In this method,DFT first should be pretreated to get a simplified fault tree(FT);then the FT was modularized to get the independent static subtrees and dynamic subtrees.Binary decision diagram(BDD)analysis method was used to analyze static subtrees,while an approximation algorithm was used to deal with dynamic subtrees.When the scale of each subtree is smaller than the system scale,the analysis efficiency can be improved significantly.At last,the usefulness of this DFT analysis method was proved by applying it to analyzing the reliability of electrical system.     

Fault Tree Analysis of CNC Machine Tool Based on BDD Technology

CNC machine tool is a large complex system which contains both mechanical and electrical components.As one of these components,the spindle is crucial for the performance of CNC machine tool.To improve the quality of CNC machine,the reliability of spindle was evaluated in this paper using a fault tree analysis(FTA)method.The FTA method is a set of calculation methods based on Boolean algebra.However,it is difficult to analyze a large and complex fault tree with inaccurate results and low efficiency as well as the complexity of time and space.Both of them will result in the so-called "combinatorial explosion".To overcome this problem,the analysis method based on binary decision diagram(BDD)was introduced in our works,and a sorting method about bottom events was also recommended which can reduce the size of the BDD effectively.     

基于数控机床故障信息的可靠性模糊分配

提出一种基于用户反馈的数控机床故障信息的可靠性模糊分配方法.通过对某机床厂的某系列数控机床故障记录数据进行统计整理,分类得到10个子系统,对故障信息进行分布模型优选、参数估计和皮尔逊χ2法假设检验,建立整机和各子系统的故障间隔时间的可靠度函数.在分析影响机床故障间隔时间的4种因素基础上,用熵权法求解权重进行加权,引入模糊数学理论,建立机床整机故障率的分配模型,指导机床可靠性指标的再分配过程.基于故障信息的这个方法更具实际应用性,能较好地解决机床可靠性的再分配问题,提高整机系统的可靠性水平.     

数据挖掘技术在数控机床可靠性分析中的应用

数控装备的可靠性研究的故障模式及影响分析方法通常采用频率法,该分析方法效果良好但过于繁琐。为此,采用数据挖掘技术中的关联规则方法,找出零(元)部件或系统可能发生故障原因和故障模式,为故障模式分析提供有效的方法。并给出关联规则算法的具体步骤。实例证明,该方法实用,有效。     

基于GO法的电动静液作动器可靠性分析

采用与故障树分析(FTA)对比法,研究了电动静液作动器(EHA)系统基于GO法的可靠性分析与安全评估方法．阐述了GO法的具体分析步骤,构建了EHA系统的GO图模型,分别利用GO法和FTA法对EHA系统进行了可靠性定量分析,并将结果对比,验证了GO法在EHA系统可靠性分析和安全评价中的可用性与正确性．     

数控车床的可靠性分析

应用数理统计的方法分析了CAK3275V型数控车床的故障现象、故障部位、故障原因,指出了该型车床最薄弱的环节,为机床的制造商提高该型数控车床固有可靠性提供了有价值的参考数据,同时提出了一种提高数控车床工作可靠性的方法。     

Machine Tool Fault Information Management System Softw are Development

In order to collect failure data conveniently and reserve reliability research data,the data collection software,the machine tool fault information management system, was developed. The method to computer numerical control（ CNC） machine tool reliability data collection was introduced. Through designing the form and applying SQL Server 2008 as the database and Visual Studio 2005 as the development platform,establish the database,develop the software based on the early stage work,and realize the comprehensive statistical information, laying the foundation for further data analysis.     

数控机床故障分析与可靠性评价技术的研究

针对传统数控机床可靠性建模时只考虑故障间隔时间而忽略故障性质的现象，提出兼顾机械故障和电气故障的混合威布尔分布模型，进而提高模型准确度.利用最大似然法来确定混合威布尔分布模型参数，用皮尔逊相关系数来确定数控机床各故障时间之间的关系.并通过K-S方法对模型进行检验， 最后确定其符合混合威布尔分布，并运用可靠性评定方法得出数控机床的平均无故障时间.     

基于模糊GO法的闭环民航运输机防滞刹车系统可靠性分析

对于结构复杂的闭环系统,使用传统FTA方法分析其可靠性较为繁琐。模糊GO法是一种基于GO法并得到改进的系统可靠性计算方法,相比较于FTA方法,模糊GO法更具有逻辑观念,能更精确的表示闭环系统可靠性的不确定性。以模糊GO法为分析基础,结合状态枚举法(以下简称枚举法),对某型闭环民航运输机防滞刹车系统进行可靠性计算,计算结果与FTA计算结果相比较,表明模糊GO法更适用于闭环系统的可靠性分析,为闭环系统可靠性分析提供一种新的思路。     

基于故障树的数控机床故障诊断系统

数控机床的故障诊断不及时不准确,会给制造企业带来巨大的经济损失,因此,数控机床的故障诊断与维护一直是制造业研究的热点之一。本文在分析数控机床特点的基础上,运用故障树分析法建立数控机床主要部位的故障树模型,依据此模型开发了一套基于故障树的故障诊断系统,该系统具有诊断速度快、诊断结果准确率高的特点,有效实现了数控机床故障的智能分析诊断。     

Reliability Analysis on Repairable System with Dual Input Closed-Loop Feedback Link Considering Shutdown Correlation Based on Goal Oriented Methodology

Goal oriented( GO) methodology is a kind of success oriented system reliability analysis method and has been used widely.The repairable system with dual input closed-loop feedback link( DICLFL) considering shutdown correlation didn't make reliability analysis accurately based on existing GO methodology. So, a reliability analysis method used to deal with DICLFL considering shutdown correlation is provided based on GO methodology.Firstly, a new operator, which is used to describe DICLFL considering shutdown correlation,whose number is 1,is created and named as Type 9C operator. And then,the formulas of type 9C operator are derived based on Markov process theory. Finally,the new method presented in this paper is adopted to conduct the reliability analysis of an electro-hydraulic servo speed control system. The analysis result is compared with those of Monte Carlo simulation and fault tree analysis( FTA). The comparison results show that this new reliability analysis method based on GO methodology is feasible and meaningful for reliability analysis of repairable systems with DICLFL considering shutdown correlation.Meantime,it will be useful for more other applications.     

基于Sugeno模糊模型的数控机床故障诊断法

在数控机床的故障诊断中,许多对数控机床故障征兆描述的诊断规则都是诊断专家的诊断经验,具有很大的随意性．文中将Sugeno模糊模型用于数控机床故障诊断系统的方式,实现了对各个诊断专家诊断结果的模糊综合,补充了诊断专家诊断知识的不足,消除了诊断专家诊断结论的随意性,保证诊断结论的准确,利用该方法基于诊断专家系统技术可以实现对数控机床的自动诊断,而且诊断结果准确、可靠．     

矿井防尘供水管网系统的GO法可靠性分析

为保障煤矿生产的安全运行,采用GO法分析矿井防尘供水管网的可靠性.以双鸭山某矿防尘系统为例,根据其工作原理和结构建立GO图,利用概率公式算法对防尘供水管网系统进行定量和定性的GO运算,获得了系统的状态概率和最小割集.结果表明,比故障树法对同一系统的分析结果更精确.GO方法能够反映系统原貌,非常适合模拟有序列过程的状态系统.对于较复杂的系统,GO法则显得比较简单,优势更加明显.     

Application of MBAM Neural Network in CNC Machine Fault Diagnosis

In ruder to improve the bidirectional associative memory (BAM) performance, a modified BAM medei(MBAM) is used to enhance neural netwcrk(NN)‘s memory capacity and error correction capability, theoretical analysis and experment results illuminate that MBAM performs much better than the original BAM. The MBAM is used in computer numeric control(CNC) machine fault diagnosis, it not only can complete fault diagnosis correctly but also have fairly high error correction capability for disturbed Input Information sequence. Moreover MBAM model is a more convenient and effective method of solving the problem of CNC electric system fault diagnosis.     

基于系统因素分析法和优劣解距离法的全寿命周期故障排序

根据数控机床的故障数据特征,从全寿命周期角度,提出了一种基于系统因素分析法和优劣解距离法(DEMATEL权重-TOPSIS法)的评价方法。该方法是将设计故障模式、影响度及危害性分析(FMECA)的风险优先数法(RPN)计算值与过程FMECA的RPN计算值的关系值作为系统因素分析法(DEMATEL)的输入数据得到优劣解距离法(TOPSIS)所需的权重值,再应用改进的TOPSIS距离公式对故障模式进行排序。利用这种方法对伺服驱动系统故障进行分析,并与传统的RPN法相比,克服了传统RPN的数学缺陷,确定了伺服驱动系统的薄弱部件。通过计算分析表明,该方法的评价结果符合伺服驱动系统的实际情况,具有一定的实用性和可行性。     

GO法与故障树可靠性建模的比较研究

ＧＯ法与故障树（ＦＴＡ）是两种不同的系统可靠性分析方法,二者在建模的方法上存在明显差异⒀通过实例对ＧＯ法和ＦＴＡ的建模进行了比较,分析了二者之间的异同点,并进一步说明了两种方法各自的使用范围和优缺点⒀ＧＯ法是以成功状态为导向, 从系统能够正常运行或信号流能正常通过的状态中得到系统的模型; 而ＦＴＡ正相反, 它是以故障状态为导向, 在系统故障状态下逐级查找造成系统故障的原因,从而得到系统的模型⒀与ＦＴＡ相比,ＧＯ法具有模型结构紧凑,易于修改、核实等优点, 同时对于分析多状态、有时序和流程性系统的可靠性具有独特的优势     

数控机床可用性研究综述

数控机床可用性是可靠性、维修性和维修保障性的综合反映,是用户最为关心的一个特性。它不仅受数控机床功能故障的影响,也受诸如精度退化、性能波动、漏油等性能故障的影响,因此,孤立地研究国产数控机床的可靠性（功能故障）不足以维持产品的“可用好用状态”。分析了国产数控机床可用性的现状及研究意义,对数控机床可用性建模方法和数控机床维修决策方法的国内外研究现状进行了阐述,总结了数控机床可用性研究存在的问题和发展动态,对基于元动作单元的数控机床可用性系统化建模和以可用性为中心的数控机床主动维修决策两个亟需解决的关键科学问题提出了见解,以期为数控机床可用性研究提供思路。     

YAG激光器系统可靠性分析中GO法的应用

GO法是一种以成功为导向的系统概率分析技术,已应用于可修系统的可靠性分析。YAG激光器振荡阈值较低、能量转换效率较高,在室温下能以连续或脉冲方式工作,具有广泛的应用领域。该文应用GO法分析YAG激光器系统的可靠性,得到系统平均无故障工作时间等重要可靠性指标。对各部件的故障率和维修率的重要度进行了分析,指出闪光灯是影响YAG激光器系统可靠性的最重要部件,讨论了改善YAG激光器系统可靠性的措施。说明GO法适用于YAG激光器系统的可靠性分析,可进一步推广并应用于其他激光器系统。     

CNC系统软件与通信接口设计的解决方案

为快速设计多任务实时的计算机数控（CNC）系统软件原型，采用模型驱动的方法对其进行需求、结构和行为的建模分析、从需求分析捕获到软件的功能需求，由结构分析把功能需求映射到具体的类或对象，通过行为分析建立这些类或对象的行为操作，解决了主从系统之间的通信接口问题，以确保主从系统可靠地进行信息交互，从而满足了多任务CNC系统软件设计时的需要．文中还通过对通信管理状态机的分析，给出了基于主机通信接口的方案，利用这些方法和方案设计CNC系统的原型并进行测试，所得结果验证了这些方案的可行性．     

监测与诊断系统中传感器信号可靠性的确认

根据设备监测与诊断系统诊断对象的复杂特点,提出了一种基于发生率的方法对传感器信号可靠性进行确认.通过在线采集一定时间内的数据,在规定的假设空间内,从证据中推导证据.对传感器信号的可靠性确认通过失效和设计检测处理,在事件发生率计算基础上,给出了规定假设空间内传感器信号可靠性的确认概率分配计算方法.