Study On Reliability Test Of Power Tool Rest Based Fault Analysis

Power tool post as the key component of CNC lathes, turning centers.etc,whichreliability directly affect the performance, reliability, stability and efficiency of the overallunit. Therefore, the reliability of in-depth study for the power tool rest is of greatsignificance.As the basis of reliability study, Failure analysis and reliability test plays a vital role inthe reliability work. In this paper, as the power tool rest for study object, criticality analysisand fault correlation analysis were adopted, and the first failure time reliability model wasestablished. On the basis of the results of failure analysis and reliability model, thereliability test of power tool rest is designed, and test items, test time and the sample size isdetermined.In this paper, firstly, according to the structure and working principle of tool test andthe modularity theory, the power tool rest was divided into several appropriate parts. On thebasis of the partition, this paper could find out the weak link which can impact power toolrest system reliability by the criticality analysis. Based on the most popular standard calledMIL-STD-1629A from the U.S. Department of Defense, minimal cut set diagnosticimportance was used to judge severity; weighting factors of experts was introduced todeterminate failure effect probability, and then the criticality was determined with thecriticality formula. At last, fuzzy logic-based expert system was adopted to conclude therisk level comprehensively. Secondly, based on the fault hierarchy of power tool rest,failuremechanism and failure relation analysis, the correlation matrix could be established, whichdetermined the interaction relationship and extent between each subsystem. Furtherintroduces DEMATEL, a directed graph was drawn; influence matrix was established.According to calculate the indicators that could indicate relationship among the indexfactors, the analysis of influence relationship between related fault index was proceeding.Then, fault transitive process among related failures was gotten quantitatively, and at last,the cause and degree which impacted fault transitive process could be found out. Thirdly,according to fault information of the previous power tool rest products, the first failure timereliability model was established. Finally, based on the results of failure analysis andreliability model, reliability test project of power tool rest was designed. According to the results of failure analysis and reliability test items was determined; according to the firstfailure time reliability model, the test time and sample size were obtained, wherein it put thefirst time as judgment point, carried on the fault-free hypothesis.