| Advanced CNC machine tools and basic numerical control equipment is thefoundation of realizing industrialization and modernization, so the development ofequipment manufacturing has global and strategic significance. However, comparedwith the imported machine tools, under the same precision level, the numericalcontrol machine tool made in China is significantly lower in reliability. If we want todevelop the domestic machine tool manufacturing industry, the reliability is thecritical at present.At present, domestic reliability research developed rapidly, but the evaluationresearch is limited to a single index, lacking overall evaluation about it. This topic isderived from the major projects of national science and technology “Comprehensiveand on-site assessment specification research of NC machine toolsâ€, aims to researchthe reliability evaluation and multi-index comprehensive evaluation method of NCtools. Basing on foreign Rambaudi five-axis machining center’s data in enterprise,researched the reliability and comprehensive evaluation method.According to the specification of reliability, screened failure data of processingcenter, and prepared for the following analysis. According to these field data, choosethe initial model and then carries the parameter estimation and fitting inspection usingK-S hypothesis testing, calculating the mean time between failures MTBF and meantime to first failure MTTFF; Establish evaluate criterion of fault equivalent,calculating the average breakdown of the machining center equivalent D; Using theactual value to calculate the mean time to repair MTTR and availability of A.In the comprehensive reliability evaluation, the model is based on fuzzycomprehensive evaluation method. First to set up the evaluation indexes andevaluation levels, and then using subjective and objective method to calculate theindexes’ weight. Choose the subjective method of AHP and objective method ofKantiray to decide the weight of indexes. Finally, using the concept of correlation function in extension method, through standardized and normalized the associatedvalues acquire the membership degree of assessment matrix, and finally get theevaluation results through linear multiplication.Based on above algorithm, developed a comprehensive evaluation software inMyEclipse environment, the overall adopts B/S structure, data analysis and storagemainly through Java access to the Oracle database, and finally using JSP to display. Inorder to convenient to operate this software, and easier to maintain, AJAX, JDBC andStruts have been used in this development. According to the fault informationcollected by the software, get the reasonable evaluation results. This softwareprovides a convenient to get the reliability comprehensive performance. |
