Research On Optimization Of Rail Grinding Pattern In Curve Section Of Metro

Metro is an important component of urban rail transit system,which plays an increasingly important role in solving urban traffic congestion and improving passenger transportation structure.The sharp curve of the metro line brings great challenge to the upgrading and maintenance of the line technology.As a means of active line maintenance,rail grinding can be used for preventive grinding to prevent the occurrence of disease,and also for repairing grinding to control the spread of disease,thus becoming an effective measure to obtain good wheel-rail matching characteristics and train dynamic performance.As a key factor in carrying out grinding operations,the grinding pattern determines the final grinding effect and then affects the curve passing performance of the metro,which is a key and difficult point in grinding technology.Based on the characteristics of the metro operation,the optimization research on the rail grinding pattern in metro curve section is carried out.The main contents and results are as follows:(1)Based on the structure and nonlinear characteristics of metro vehicles,the multi-body dynamics software SIMPACK is used to establish the dynamic modelling of metro train system in the form of “one-action-one-towing”,which is used for the subsequent simulation calculation in the optimization design process of the rail grinding pattern of the curved section of the metro,and check the train dynamic performance and wheel-rail contact characteristics before and after the grinding pattern design.(2)On the basis of analyzing the principle of sequential and asymmetrical grinding wheel,the rail profile is constructed by using B-spline curve combined with the features of multi-segment straight line envelope.Based on the contact state between grinding wheel and rail,the two-dimensional geometric relationship between grinding wheel and rail is analyzed.In the meantime,the mathematical relationship between grinding pattern parameters and rail grinding profile parameters is clarified,which laid a foundation for the optimization design of rail grinding pattern.(3)Based on the mathematical relationship between grinding pattern parameters and geometric parameters of rail grinding profile,a rail grinding pattern optimization method is proposed.In this method,design variables and constraint are reasonably selected,multi-objective optimization considering the wheel-rail contact stress,wheel-rail lateral force and grinding amount are given.The optimization model is solved based on chaotic micro-variation adaptive genetic algorithm.The method is applied to the repairable grinding of worn rail in metro curve section.The optimization results show that the proposed algorithm has high feasibility,could obtain ideal grinding pattern and meet the expected grinding effect.The wheel-rail contact characteristics and train dynamics performance are significantly improved after grinding.