Reliability Evaluation Of Machining Center Based On Failure Correlation

To improve the reliability of the machining center is of great significance to enhance themarket share, reputation and market competitiveness of domestic machining center.Combined with the national natural fund project, with a series of17sets domestic machiningcenter as research object, this paper systematically analyzes the field failure data andconstructed a comprehensive evaluation system of machining center reliability considering itsfailure correlation.Firstly, using the ANP network analytic Hierarchy Process, with the aid of SuperDecision software that take fault effect as the goal layer, considering the correlation betweenfault occurrence, correlation analysis was carried out to the failure mode of machining centerBased on the influence degree sorting of all failure modes, with the help of the classiccriticality calculations, calculated the hazard values of each failure mode. Then got thecoefficient assignment of fault level according to the hazard values, finally obtained theequivalent failure rate and completed the failure effect evaluation of the whole machine.Secondly, the existence of failure correlation changed the previous normal modelingprocess of the whole machine. Based on the time between failures calculated the reliabilitymodel of the subsystem of machining center. The reliability distribution functions of eachsubsystem was treated as its edge function, with the introduction of the Copula connectionfunction, then estimated parameters by using computer programming operations and test thedistribution fitting effectively. Selected the optimal after testing model and got the jointreliability function of the whole machining center. Then campare with reliability function ofthe whole machine when its failures are independent, and the struction of reliability functionof the whole machining center is very reasonable. We got the point estimates of MTBF andcompleted the use of reliability evaluation of machining center.Finally, based on the first failure time of machining center, reliability modeling of firstfailure time,reasonable parameter estimation and distribution fitting test were implemented,and then obtained the inherent reliability evaluation of machining center. Consolidatingresulting mean time between failure MTBF, equivalent failure rate D, selecting theappropriate comprehensive evaluation model, using the coefficient of variation method toobtain the objective index weight, then got the comprehensive evaluation value Q whichreflect the reliability level of whole machining center.