【作者】 葛红玉；

【导师】 张根保；

【作者基本信息】 重庆大学 ， 机械工程， 2011， 博士

【摘要】 论文针对数控机床可靠性控制中存在的问题,分析了可靠性与装配过程之间的关系,明确了整机可靠性主要由部件本身的可靠性和部件间的连接可靠性来保证的概念;提出了数控机床基于可靠性的功能分解思路,分解围绕三条主线展开:对机床功能进行了“整机功能——部件间连接功能、部件基本功能”的分解;将各部件间的连接功能进行“部件——连接部位——连接方式”的分解;将各主要部件进行“功能——运动——元动作”的分解,并建立了三条主线的分解模型。针对分解过程,定义了分解中各事件的专有符号,建立了各分解模型相应的成功树,并对成功树中各事件及事件间的关系进行了数学表达。针对数控机床装配可靠性难以量化的问题,通过分析数控机床装配过程与机床功能形成过程之间的关系,确定了在保证设计与加工可靠性的基础上,数控机床装配可靠性直接影响机床功能形成过程可靠性,直接分析装配可靠性需要分析各装配阶段的工艺过程,这样就使得装配可靠性更加难以量化。基于上述分析,本文针对装配可靠性与功能形成过程可靠性间的关系,将装配可靠性的定量分析转化为对功能形成过程可靠性的定量分析,使得问题得以解决。本章根据功能成功树中各事件间的逻辑关系,将成功树转化为以“成功”为导向的GO图模型,从而利用GO法运算,进行了数控机床功能形成过程可靠度(装配可靠度)的运算。为了实施装配可靠性的控制,分析了部件间连接方式及部件元动作可能的故障表现即装配缺陷。针对数控机床装配缺陷源较多、不易控制的问题,利用熵值法,提出了装配缺陷熵权的概念,计算了数控机床装配过程中缺陷的熵值及熵权,结合专家权重,确定了装配过程可能产生的主要缺陷模式,并分析了主要缺陷源。在确定了主要缺陷模式及主要缺陷源的基础上,制定了主要缺陷源的控制措施。利用多色集合理论建立了主要缺陷模式与主要缺陷源、主要缺陷源与控制措施之间的关联矩阵,并分别建立了布尔控制表,将装配可靠性控制的相关信息进行了集成,对装配可靠性的直观化控制具有一定意义。为了对本文研究的数控机床装配可靠性建模及控制技术的有效性进行评估,利用灰色系统理论建立了整机装配可靠性历史数据、各功能部件装配可靠性历史数据、部件间连接的可靠性历史数据之间的关系模型,求解了整机装配可靠性历史数据的模拟值,在模拟精度有意义的前提下,对实施了可靠性控制技术的历史数据进行了未实施还原模拟。利用GO法对相应可靠性历史数据进行了实际值计算,并与未实施控制技术的模拟值进行了对比分析,表明本文研究的装配可靠性控制技术对于控制数控机床可靠性是有效的。上述研究结果均应用于加工中心装配可靠性的建模及控制方法的研究中。更多还原

【Abstract】 Aiming at the problems of reliability control for CNC machine tools, this paper analyzed the relation between the machine reliability and the assembly process, confirmed that the machine reliability is formed by the connection function reliability and basic function reliability of components. Besides, decomposition methods of CNC machine tools functions including decomposition of the whole equipment function, joint function and unit function. The whole equipment function is decomposed for joint function and unit function; joint function are decomposed for connection parts and connection mode; unit function is decomposed for movement and meta-action. Then, decomposition model is established. On account of the decomposition process, exclusive signs are defined for the events in the decomposition model and the success trees of different decomposition models are built respectively. The mathematical expressions of relations among different events and in events themselves are given out.Facing with the unquantifiablility of reliability of CNC machine during assembly, after analyzing the connection relation between assembly process and function formed process, it is confirmed that on the basis of guaranteeing design and machining reliability. CNC machine assembly reliability impacts directly on machine function formed process reliability. Analyzing assembly reliability directly needs to analyze the assembly process, which makes it difficult to quantify the assembly reliability. Above all, the paper aims at the relation between assembly reliability and function formed process reliability, turns quantification analysis of assembly reliability into quantification analysis of function formed process reliability which leads to the solutions. The GO-diagram model guided by Success is built by success tree according to the logical relation among events. The reliability of CNC machine assembly process is calculated by GO method.To put the control technology of assembly process reliability into effect, the failure performances of connection mode and the meta-action which are called reliability defects are analyzed. Aiming at some problems, such as the large amount of sources of reliability defects and uneasily-control, Entropy Method is utilized to give the conception of Entropy Weight of reliability defects during assembly. The Entropy Weight and the value of Entropy are calculated combining with the Experts Weight, the main defects patterns which may occur during the assembly process are confirmed and the main defects sources are analyzed.On the basis of confirming main defects and sources, the assembly reliability control measures are established. Moreover, utilizing the polychromatic sets theory, matrixes between main defects and main defects sources, main defects sources and control measures are related. Boolean Control forms are built respectively and the relevant information of control technology of assembly process reliability is integrated, which contributes to the clearness of assembly reliability.To evaluate a set of reliability modeling during assembly process of CNC ma-chine and the effectiveness of control technology studied in this paper, Grey System Theory is utilized to build a model of the relation of historical data of whole machine assembly process reliability, assembly process reliability of joint function and reliability of unit function. In addition, the analogue value of historical data of assembly process reliability is worked out. On condition that the simulation precision is effective, the historical data controlled by reliability control technology is simulated uncontrolled. Using GO-method, the corresponding historical data is actual-valued calculated and the analogue values which are not controlled by control technology are compared and analyzed. It proves that it is effective for control technology of assembly process reliability to guarantee the reliability of CNC machine tool.The study results above are all able to use in the reliability study of assembly process of machining centre which has been proved by instance.更多还原