| With the development of society,the complexity of electromechanical products is increasing.It is more difficult to model the reliability of electromechanical systems.Aiming at the problem that system structure information and failure mode information cannot be contained in the traditional reliability modeling,the Meta-Action Chain Methodology(MCM)is presented to model the operating modes and failure modes of the system.Compared with traditional modeling,this method can be directly used in the design,processing,assembly and maintenance.In this paper,electromechanical systems are taken as the research objects.Each state of the electromechanical system can be expressed by the combination of the meta-action structure chain and the Meta-action operating series chain.So that the structural information,faulty mode information,economic characteristic information,operation parameter information and other information of the electromechanical system can be integrated into the calculation chain of system reliability.On the other hand,the reliability evaluation results can be mapped to the fault sensitive parameters in real time,which can provide sufficient basis for the maintenance decision of the system running process and the improvement of product quality.Specific research includes:(1)Definition and modeling method of electromechanical system using meta-action chain methodology(MCM).The definition of the structure chain and the operating series chain are given.System structure information and system operation information are integrated into the system reliability modeling process.The establishment process of the element action chain of the electromechanical system is proposed.The continuous operation space of the electromechanical system is discretized,and the model time solving accuracy ? is introduced to define the state of each meta-action chain and the operating state space of the electromechanical system.On the other hand,with the Markov Transition Probability Matrix,a meta-motion chain state transition directed graph of the electromechanical system is established.According to the theoretical model,the solution algorithm and algorithm flow chart are given and the corresponding program is realized by Matlab.Taking the end gear tooth graduation numerical control turntable of TH63 series machining center as an example,combining with the structure chart of the turntable and the results of Failure Mode and Effects Analysis(FMEA),the reliability of the system under different operation modes is estimated.The dynamic decay curves were plotted.Compared with the curve obtained from the classical Weibull distribution model,the reliability of the method was verified.Taking the worn-out,switched-on and alternating-stress-type action faults as an example,the causes of microscopic failure and macroscopical values are established by using Power Law Process(PLP)and logarithmic normal distribution(LND)Reliability of the coupling between the CNC machine tools for product reliability evaluation.(2)Analysis of NC machine tool operation fault based on meta motion chain.The proposed meta-action chain method is used to analyze the cause of the failure of NC machine tool products.At the same time,the quantitative calculation model can provide support for the fault distribution parameters of each model of the meta-action.Taking the wear of worm gear and the failure of gear shaft alternating stress as an example,the relationship between the microscopic failure cause and the probability of failure occurrence is analyzed.The resulting probability curve for the occurrence of a fault event can be fused and applied in the system reliability curve established in Chapter 2.system structure information,system operation information,microscopic failure reason information and macro reliability model are highly integrated which enhances the scope of reliability modeling.(3)Preventive maintenance strategy modeling and analysis based on reliable operating envelopes.Defines Reliable Operating range and Reliable Operating Envelope.The Coincidence Degree of Reliable Operating Range is defined for one-dimensional cases.The reliable operation space envelope is used to group the parts with different fault sensitivity and different operation time dimensions in the system.The economic characteristic information,structural information and operation mode information of the components are integrated,which makes the preventive maintenance of electromechanical products more pertinent.A maintenance strategy matrix is proposed.The genetic algorithm(Genetic Algorithm)is used to optimize the traversal matrix of maintenance strategy,and the corresponding algorithm and algorithm complexity are given.Taking MKS16 series CNC grinding machine and FMS80 flexible production line for example,the applicability of the established maintenance strategy model in different row mode and different fault sensitivity conditions of CNC machine tools are verified respectively,and compared with the classic maintenance strategy.(4)CNC machine tool reliability improvement modeling and analysis based on the user's expected degree of conformity.The introduction of user expectations distribution describes the specific meaning of product quality.The Mahalanobis distance is used to calculate the difference between the user's expected distribution and the actual quality characteristic of the product,and the corresponding Quality Loss Function is established to define the quality of use of the CNC machine tool.According to the mass loss function,the mass loss of each quality characteristic is calculated respectively,and a corresponding user's expected compliance vector(Coincidence Degree Vectors of Customer Expectations)is obtained.The utility cost ratio of each quality improvement measure is calculated,and the optimized sequence of reliability improvement of the electromechanical system is obtained.Taking MKS16 series numerical control grinder as an example,the quality evaluation index system of the product is established,and the optimal control sequence of the reliability improvement measure is obtained,which verifies the practicability of the model.(5)CNC machine tool reliability economic characteristics modeling and analysis.The concepts of Marginal Utility and Marginal Cost are defined.Based on Revenue Requirements Method and interval analysis method,the relationship between reliability input and reliability benefit is deduced,and the quantitative calculation model is given.The establishment of a specific mechanical and electrical reliability analysis of economic processes.The simulation software was used to simulate various parameters of the reliability economic model of electromechanical system,and the iterative process of dynamic updating of product reliability input and reliability return was calculated,which provided sufficient decision-making basis for the selection of product reliability control points.The process capability of the key processes of product production was calculated.The process capability of the product production process was analyzed by the spindle machining process,and the economic loss factor of the product processing was eliminated... |
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