Research On Maintenance Strategy For Turret System Based On Failure Interaction

The rapid development of CNC machine tools has higher requirements for keyfunction units. Turret system, as a typical repair system, is an important part of CNClathe. It is achieve to reserving cutter, gripping cutting tool and changing tool. Theturret system is complex repairable system integrated with mechanical, electrical andfluid technology. The advanced function and maintain function of CNC machine toolshas direct impact on the whole performance of the machine tool. So there is a greatsignificance to research maintenance strategy of turret system.Maintenance is the entire activities in order to maintain or restore engineeringsystem to the required technology or active conditions. It can improve equipmentutilization, ensure production, and improve enterprise efficiency. The development ofa reasonable maintenance programs and appropriate maintenance interval has animportant impact on the enterprise’s production. Turret system as the research object,failure interaction, randomness and failure cause and effect is considered. The turretsystem maintenance programs and preventive maintenance intervals between failuresand maintenance strategy is studied.Firstly, based on the Bayes theory, the reliability model of turret subsystem isbuilt. Four reliability distribution trend was tested to determine the optimaldistribution by using Minitab; considering the characteristics of a small sample of thesubsystem data, Bayes theory was used to build the subsystem reliability model toensure the accuracy of the parameter estimates; Matlab is used to calculate thereliability model parameters based on Gibbs sampling in full condition which avoidthe intensive numerical integration of calculated amount and the dependence of thedimension and complexity; the goodness of fit test and heteroscedasticity test are usedto verify the correctness of the model assumptions.Secondly, the correlation coefficient of the failure interaction subsystems iscalculated. Failure analysis is used to analysis the historical fault data to confirm thedrive system and sealing systems, Copula function as connection function isintroduced to reliability theory. Different Archimedes family Copula function is selected as a link function to establish the function of correlation coefficient betweenfailure interaction subsystems with the subsystems reliability model. Artificial fishswarm algorithm with the capacity of overcoming local extremum and achieving theglobal extremum is used to calculate the correlation coefficient between the failureinteraction subsystems. With D test, the average cumulative error test and mean squareerror of the test, the most suitable and optimal Copula connection function isdetermined.Again, the preventive maintenance strategy based on the failure interaction isstudied. The change of two components system failure rate and reliability underfailure interaction is analyzed, then the reliability model is bulit. For reliabilitycentered maintenance, reliability threshold is determined and establish the preventivemaintenance strategies. preventive maintenance interval is determined throughsimulation. Then the change of preventive maintenance interval between independentand failure interaction has been contrastive analyzed. The influence of preventivemaintenance interval is analyzed while reliability threshold and correlation coefficientchanging.At last, Optimization of turret system maintenance strategy hybrid multi-attributeprogram is selected. A combination evaluation method is built based on the idealsolution and the gray relational degree. The degree of closeness between candidatesolution and ideal solution is investigated by the close degree of the position and thesimilarity degree of shape to do turret maintainability strategy optimization which ismore objective and comprehensive. Considering the experience of the expert judgmentand fully reflecting the importance of each attribute, subjective weights and objectiveentropy weight was combined to obtain the overall weight, projection pursuit was usedto solving the defects when preference coefficient was selected in traditional way. It ismore scientific and objective.Through failure interaction maintenance strategy research of turret system, Turretsystem is able to carry out timely and effective maintenance, improve turretavailability to ensure continuous production enterprises, and increase the economicefficiency of enterprises has important guiding significance.