Study On Vibration Behavior And Prevention Measures Of Polygon Wheels Of Emus

With the increasing speed of the train,the interaction force between the wheel and the rail is increasing,and the wheel has various defects such as wear and fatigue,and the wheel polygonization is one of the common wheel defects.The wheel polygonization will aggravate the vibration of vehicle components,reduce the ride comfort,reduce the service life of parts,increase the cost,and even affect the safety of train operation.Therefore,it is necessary to pay attention to the wheel polygonization and control it in the practical application of train.Taking China Railway Chengdu Group as an example,this paper introduces the noise meter,wheel lathe and trackside detection equipment which be used to detect wheel polygonization and the corresponding determination standards,and summarizes the influence of wheel polygonization on the noise of track passenger compartment,failure of parts and maintenance costs.Taking one EMU as the research object,the wheel polygonization was tested by out-ofroundness tester,and it was found that all of the wheel showed obvious 18-19 order wear.The acceleration sensors are arranged on the axle box,frame and motor of the vehicle,and the operation test is carried out in Chengdu-Mianyang-Leshan passenger dedicated line and Chengdu-Chongqing passenger dedicated line.After the wheel is re-profiled,the operation test is carried out again in Chengdu-Chongqing passenger dedicated line.The test results show that the vibration at the corresponding frequency of the 19 order wheel polygonization is obvious before wheel re-profiling,and the acceleration amplitude at the same frequency is significantly reduced after wheel re-profiling.The maximum average vertical vibration acceleration of axle box,frame and car body in the whole process and highspeed section after wheel re-profiling is lower than that before re-profiling,and the reduction of car body acceleration is the most obvious.In order to analyze the influence of wheel polygonization on the dynamic behavior of train,a vehicle dynamic simulation model which consistent with operation test was established based on multi-body dynamic theory.The correctness of the model is verified according to the indexes of operation stability,safety.Taking the measured wheel polygonization as the input,the vehicle dynamic simulation is carried out according to the operation test conditions.The simulation data and the measured data are compared from the time domain and frequency domain,and the influence of vehicle speed,wheel radial runout and wheel polygonization order on vehicle dynamic performance is analyzed under the condition of wheel polygonization.The results show that the dynamic simulation model can accurately reflect the vibration characteristics of wheel polygonization.In the presence of wheel polygonization,there is a sensitive vehicle speed,train should try to avoid long-term operation at this speed;excessive wheel radial runout value will cause safety risks such as wheel load shedding.When the radial runout value exceeds the standard,it is necessary to timely reprofile or replace the wheelset.The influence of wheel polygonization order on vehicle dynamic performance is related to vehicle speed.When the order of wheel polygonization increases to a certain value,the negative impact of polygonization is gradually reduced.In view of the prevention measures of train wheel polygonization used in the field,the relevant test and tracking test results show that wheel re-profiling,installation of wheel tread cleaning device,rail grinding and adjustment of operation road can all have a certain inhibitory effect on the generation of wheel polygonization.The relevant departments of the railway group can take the above measures according to the specific situation to realize the comprehensive prevention and control of train wheel polygonization.