Research On Early Failure Active Elimination Technology Of Electromechanical Product

Aiming at the problems of frequent early failure,low inherent reliability and operational reliability of domestic electromechanical product,a set of early failure active elimination method based on meta-action unit was proposed in order to improve the reliability of electromechanical product in this paper.The meta-action theory and FMA decomposition method were systematically extended.The concept of key meta-action was proposed,and the specific extraction method was also given.The standardized modeling technology of meta-action unit was studied.The collected meta-action failure data were analyzed,and Bounded Bathtub Intensity Process(BBIP)model were used to describe the early failure occurrence mechanism of electromechanical product meta-action.The early failure period of electromechanical product meta-action was obtained,and the relationship between the previous and the subsequent failures of meta-action unit was explored.The definition of early failure mode,early failure cause and early failure mechanism of meta-action was given,and the relationship between them was studied.Based on meta-action,the quantitative criterion of failure mode was established,and the failure generation mechanism of key meta-action unit was also analyzed quantitatively.Based on failure report analysis and corrective action system(FRACAS)and meta-action unit,an early failure elimination method of electromechanical product was explored,and a corresponding failure correction implementation guarantee system was also formulated.Based on meta-action rather than static parts,the reliability allocation of electromechanical product was carried out,and the allocation results were rationally optimized,which fundamentally improves the inherent reliability of manufactured product and reduces the probability of early failure.The specific study contents include the following aspects:(1)Research on meta-action and meta-action unit modeling technology.The latest and standard definitions of meta-action and meta-action unit were given.According to the idea of"whole machine function-component motion-meta-action",the decomposition method of electromechanical product from the whole machine function to meta-action was introduced in detail.The detailed FMA decomposition criteria and corresponding meta-action unit separation rules were formulated.The concept of key meta-actions was proposed,and a key meta-action unit extraction method based on probability,detectivity,maintainability and maintenance cost(PDMC)was presented.The definition and analysis method of standardized structure modeling of meta-action unit were given,and the establishment method about it was studied.A numerical control(NC)rotary table was taken as an example,and all meta-actions and corresponding meta-action units about it were obtained by FMA decomposition method.Key meta-action and key meta-action unit of the NC rotary table were obtained by the extraction criterion.The key meta-action unit was analyzed,and its standardized structure model was obtained.The results laid a foundation for the subsequent early failure analysis based on meta-action and meta-action unit.(2)Early failure modeling and analysis of electromechanical product meta-action.The early failure of electromechanical product meta-action was defined.The sources and collection methods of the meta-action failure data were given,the failure occurrence time instead of failure time interval was preprocessed by total test time(TTT)method,and the failure trend was predicted by TTT diagram.On the basis of comparative analysis of various alternative models,BBIP method was selected to describe the failure process of electromechanical product meta-action.The mathematical properties of BBIP model were discussed,and the methods of model parameter estimation,goodness of fit test and early failure inflection point calculation were given.The instantaneous indexes and cumulative indexes of meta-action early failure impact analysis are given,and the correlation analysis model between the former early failure and latter early failure of electromechanical product meta-action unit is established.An example was given to verify the applicability and correctness of the proposed method,and the early failure periods of different meta-action units are obtained.The influence of the early failure on the overall reliability of meta-action chain was analyzed,and the relationship between the former and latter failure of meta-action unit was explored.(3)Research on early failure mechanism of electromechanical product meta-action.The definition of early failure mode,early failure cause and early failure mechanism of meta-action was given,and the relationship between them was analyzed.The meta-action failure mode is only related to its action,and the failure reason is only related to the structure of meta-action unit.The early failure mechanism analysis of electromechanical product,which takes meta-action and meta-action unit as the analysis object,solves the problems that confusing definition and difficult analysis of failure mode and failure cause in traditional failure analysis method.Based on kinetic energy theorem,the quantitative judgment criterion of meta-action failure mode was given,which improved the rationality and accuracy of failure mode classification.The types of meta-action failure mode are are less than those of traditional analysis methods,and the difficulty and workload of failure analysis are reduced.Based on finite element method(FEM),kinematics and dynamics,an early failure mechanism analysis method for electromechanical product meta-action was proposed.The key meta-action unit obtained in the second chapter of this paper was taken as the object to analyze its failure mechanism.Based on reasonable simplification,a failure mechanism analysis model was established.The failure model was solved by Newmark method,and the failure mode occurrence mechanism of this meta-action was quantitatively analyzed.(4)Research on meta-action reliability allocation and optimization technology for early failure active elimination.The meta-action achin MAC₃₄₂obtained in the second chapter were taken as the object of reliability allocation.On the basis of a large number of enterprise investigations and expert reviews,the important degree,hazard degree,occurrence degree,complexity degree,maintenance degree,maintenance cost and maturity degree of meta-action were considered as the factors influencing reliability allocation,and the time,cost and benefit cared by manufacturing enterprises were taken as the optimization objectives of reliability allocation.The weight coefficients of reliability allocation influence factors and optimization objective factors were introduced,and a new expert weight coefficient calculation method was also introduced to establish the fuzzy judgment matrix and the fuzzy decision matrix,which made the calculation results more objective.Based on the above research,a new multi-objective reliability optimization allocation method for electromechanical product based on meta-action was proposed.The advantages and disadvantages of common reliability allocation methods and the proposed method in this paper were compared and analyzed,and the results verified the rationality and accuracy of the proposed method.(5)Research on the early failure active elimination system of electromechanical product meta-action unit.According to the FRACAS idea of“closed-loop,failure zero”,a meta-action early failure active elimination system based on meta-action unit covering all stages of electromechanical product design,processing,assembly,and testing was proposed.In order to ensure the implementation of the system in enterprises,a set of early failure active elimination protection mechanisms has been established,and the tasks and responsibilities of each department of manufacturers were defined,which provided an operable method for shortening the early failure period and reducing early failure of electromechanical product.The method put forward herein was used to the relevant machine tool manufacturers,and the results verified its correctness and feasibility.