Research On Detecting Method Of The Wheel Tread Flat And Out-Of-Roundness

Wheels are the eventually stressed members of rolling stock, which pass the load to the rail and make the train in operation by rolling on the rail. Therefore, the quality of the wheels will directly influence safety. As one of the key parameters of the train wheels safety testing, it is very important whether the flat and out-of-roundness can be detected in high speed. When the wheels are running, the impact from comprehensive factors coupling also plays an important role on the track and influence the dynamic performance at the same time. It can not be ignored to evaluate the function on the track on time and correctly. There are many methods to detect the flat and out-of-roundness in the world,but most of them just suitable for low-speed or cannot be used for the quantitative detection in high speed. So the vehicle -rail function model is studied in high speed,the testing platform is designed in order to get the quantitive result.In this dissertation, the definition and formation of flat and out-of-roundness is introduced, after the model and detection method is analysed, the vehicle -rail couple dynamic model and the laser-PSD sensor which act as the core devices are given as the derection to sovle the problem. Taking the characteristics of detection object into consideration, based on WanMing ZHAI et ’vehicle-rail coupling model’, a simplified model of vertical wheel-rail forces is used.The result can be calculated by solving the differential equation with modified E-ruler method.Lots of simulation results show the performances of wheel and rail with different excitation source, the speed range of 80-140km/h is selected as the best choice to build the testing platform and detect the defects.The high speed experimental platform is built based on’Laser-PSD sensor’and the detailed inplemetation plan, the principle and the detection flow chart is introduced. All the key parts are described in detail and the error is simply analysed.After further extension, the platform and can easily get the horizontal force. So many parameters related to the dynamic performance and safety can be calculated through both vertical force and horizontal force which proves the feasibility of the platform.The arithmetic of the pratical model is anylysed and how to use the experimental platform and vertical wheel-rail forces method to calculate the flat and out-of roundness is presented. The results is proved to be correct after recheck.It shows that the detection data is good and reliable,the error is aound ±0.3mm.All of the above proves the accuary of the simplified ’vehicle-rail coupling model’, the correctness of the arithmetic and the feasibility of the platform.With further discussion about safety evaluation and control, the dissertation introduces the calculation method related to the safety, all the parameters, like derailment coefficient and overload. Combined with the vertical force, horizontal force, flat and out of roundness, it can get the final suggestion of the control factors.This dissertation reveals the research work in the’Vehicle and Track’field from another aspect, and enriches the existing theoretical research’vehicle-orbit coupling model’, especially build the bridge between the theory research and practical engineering application. The engineering measurement solution is also verified through site application.This research work provides a reference for wheel defect detection methods in the train safety testing field of high speed and the reliable data to control the safety level.