Research On Vibration Characteristics Of Rail Grinding Unit And Improvement Of Rail Grinding Quality

The interaction between the wheel and rail causes various damages and defects on the rail surface.Rail grinding using grinding trains can effectively eliminate the damages and defects on the rail surface,reshape the rail profile,improve the wheel rail contact,prolong rail service life and reduce the frequency and cost of rail replacement,ensuring the safety and stability of the train operation.Rail grinding unit is the core part of the grinding train to carry out grinding operation.Its vibration behavior has significant impact on the performance of the grinding train and the grinding quality of the rail.Therefore,the study on the structural vibration characteristics of rail grinding unit and the influence of grinding conditions on the grinding quality is important to the performance optimization of the grinding unit,the grinding quality improvement,and the research on rail grinding equipment.This thesis aims to do research on a certain type of rail grinding train produced in China,the grinding experiment is carried out under different grinding conditions by combining the field experiment and theoretical simulation research,and the field test is also carried out simultaneously.The analysis of vibration characteristics of the grinding unit under different working conditions and the impact on the grinding quality is based on the experimental results.By building the finite element model and multi-rigid body dynamics model,this thesis studies on the optimization design of the grinding unit’s structure,and verifies the effect of the grinding quality improvement by the means of simulation and experiment.The main work and conclusions are as follows:(1)This thesis summarizes the development of domestic and international rail grinding equipment and the research on the structure,stress,control and dynamics of rail grinding unit,putting forward the technical route to study the vibration characteristics and grinding quality of rail grinding unit.(2)The structure and composition of rail grinding unit are introduced.Based on the experimental result of vibration test and hammering test,it is found that the main structure of the grinding unit will be affected by a variety of excitations in the working state.The vibration generated by the interaction between the wheel and the rail is identified as the main source of vibration excitation.The main structure of the grinding unit is in forced vibration state when it is excited,and its vibration frequency shows the excitation frequency and the excited natural frequency.In order to avoid the structural resonance caused by the coincidence of the natural vibration frequency of the grinding unit structure and the main vibration frequency of the grinding unit,the structure of the grinding unit needs to be further optimized.(3)Through the comparative analysis of the field test data,the vibration characteristics and grinding quality differences of the structure of the grinding unit under different grinding conditions are studied.It is found that the grinding speed and the rail wave grinding conditions will affect the vibration and grinding quality of the grinding unit structure.Properly increasing the grinding speed can reduce the vibration amplitude of the grinding unit structure and improve the grinding quality.The increased severity of the rail corrugation or the coincidence of the corrugation passing frequency with the main vibration frequency of the grinding unit structure will lead to more severe vibration of the grinding unit structure and thus affect the quality of the rail irregularity after grinding.The measures to improve the grinding quality are put forward from the point of view of grinding process.(4)The finite element model of the grinding unit frame is established,the elastic modal analysis of the frame is carried out,and the optimization design scheme of the frame middle structure is proposed.Through the model simulation and the grinding experiment,it is proved that the grinding unit with frame optimization design can reduce the intensity of structural vibration,reduce the protrusion of the significant peak value of the rail surface irregularities by28%,and the roughness of the rail after grinding is lower than that of the prototype vehicle,the grinding quality is indeed improved.(5)The dynamic model of the grinding train considering hydraulic system is established.Through the analysis of the suspension mode of the grinding unit structure,it is found that the vertical vibration frequency of the motor and the coupling vibration frequency of the motor frame are close to the main frequency(60 Hz)of the grinding train’s vibration,which is easy to resonate.The improved scheme is proposed for the parameters of the motor feed hydraulic cylinder.The model simulation and experiment of the modified vehicle prove that the grinding unit with improved parameters of the motor feed hydraulic cylinder can lower the intensity of the structural vibration,and reduce the protrusion of the significant peak value of the rail surface irregularities by 22%,the roughness of the rail after grinding is lower than that of the prototype vehicle,therefore the grinding quality has been effectively improved.