| CNC turret is one of the key functional components of CNC machine tools,which reliability level plays a vital role in its entire service life cycle.Therefore,carry out the reliability research of CNC turret and find the weak links of the key subsystem has important theoretical application and guiding significance for the safe operation and preventive maintenance of CNC turret,and high-efficiency production of CNC machine tools.On the road from China's manufacturing power moving to the stronger one,the overall manufacturing level of the domestic CNC turret is gradually moving closer to the imported products,which structural complexity is getting higher and higher and the failure modes and failure mechanisms of the components are becoming more and more diverse.The traditional fault tree analysis methods are no longer available.To meet the analysis needs of existing products,this paper proposes the fault tree based on Monte Carlo(MC)and T-S fusion to analyze the reliability of CNC turret.The specific research work is as follows:1.Because the influence of each subsystem of the CNC turret is different,the subsystem of the CNC turret is screened to eliminate the subsystems that have less influence on the whole machine first.Based on this,the evaluation model of the key subsystem of the CNC turret was established with the analytic hierarchy process and TOPSIS.In order to eliminate the analysis error caused by the diversity of evaluation indicators,this paper selects three indicators that are consistent with the damage analysis of the CNC turret failure mode as the basis of the expert scoring.And the weight value of the evaluation index was determined by the analytic hierarchy process method,and the importance ranking value of the CNC turret system was calculated by the TOPSIS.The key subsystem of the CNC turret is obtained.2.Considering the complex of the fault tree model of CNC turret,the complicated and cumbersome of the quantitative and qualitative analysis,and the lower accuracy,the two-state fault tree model of the CNC turret is established based on the Monte Carlo simulation method.And the life distribution sampling function of the fault tree bottom event was obtained by the fuzzy fault probability of the component and assuming the exponential distribution.The reliability of the system,the distribution curve of failure probability and the mode importance value of each component are obtained by MATLAB.And the weak links of the system is preliminarily obtained.3.In the traditional fault tree analysis,it is required to clarify the fault mechanism of the system,the failure probability of the components and the degree of fault.To compensate for the above deficiencies,a multi-state fuzzy fault tree model for the key subsystem of the CNC turret was established with the TS fuzzy theory.Based on the T-S fuzzy gate rule and the fuzzy fault probability of each component,the fuzzy fault probability of the system under different fault degrees and the fuzzy importance of each component are analyzed in detail,and the weak links of the system under different fault levels is obtained.4.There is no unified evaluation standard of the result in the above analysis method,that the weak links of the key subsystems of CNC turret in the two-state and multi-state can be obtained respectively.A fusion algorithm which combined the MC simulation and TS fuzzy theory is defined.According to the model importance value of each component of the key subsystem of the CNC turret simulated by MC,the new TS fuzzy door rule is constructed.Under the new fuzzy rules,the fuzzy fault probability of different fault degrees of CNC turret and the fuzzy importance of each component are calculated,and the more accurate weak links of the system with different fault levels are obtained.This paper makes up for the shortcomings of the industry in the theoretical research of the numerical analysis CNC turret fault tree analysis,and has guiding significance for the preventive maintenance and preventive overhaul of the CNC turret. |
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