The Study Of Heavy CNC Machine Tools Reliability Assesment Method Based On Bayes Theory

The Bayes method that makes gradient reliability results as priori information ispresented to solve the problem that priori information is difficult to collect for heavy CNCmachine tools. A certain model of heavy CNC Boring and Milling machine is regarded asthe research object. The machine’s reliability model was established on the basis of itsfunction and structural characteristics and working principle. Based on the stress intensityinterference theory and the reliability model theory, the gradient reliability of the machinetool and its key parts were obtained. The results of the gradient reliability were made aspriori information to obtain the probabilistic reliability of the machine tool and its keycomponents according to the Bayes method. The two results are compared with each otherin order to demonstrate the applicability and superiority of the Bayes method that makesgradient reliability results as priori information in the heavy CNC machine tools’reliability assessment. The main content of the paper is as follows:Firstly, the present research situation of the CNC machine tools’ reliability and theapplication of traditional method and the Bayes method in heavy CNC machine tools’reliability assessment was briefly described.Secondly, the criterion of the reliability evaluation which was commonly used in thefield of mechanical products reliability was summarized. Based on the reliability modeltheory, the reliability models of the machine tool and its key components were established,in which the function and structure characteristics and working principle of the machinetool were combined.Thirdly, based on the stress strength interference theory, the gradient reliability of themachine tool and its key parts were estimated. The gradient reliability of parts were madeas priori information. The probabilistic reliability of the machine tool’s key componentswere estimated according to the Bayes method.Finally, the pyramid estimate process was used. The reliability information of themachine tool’s key components was made as priori information. The probabilisticreliability of the whole machine and its Mean Time Between Failure were estimated bymeans of the Bayes method. The results of the gradient reliability and the probabilistic reliability were analyzed and compared. To begin with, the credibility of the estimatedresults is demonstrated. In addition, it can be proved that the Bayes method which makesthe gradient reliability results as priori information has its applicability and superiority inthe field of heavy CNC machine tools’ reliability assessment.