Study On The Dynamic Behavior Of Rail Grinding Vehicle

Fatigue is one of main damage types of rail. The rail grinding can directly remove the fatigue layer of rail surface and the profile grinding optimizes the wheel/rail contact. The grinding vehicle of rail grinding train is a core mechanism in grinding operation. Therefore, the study on improving the dynamic performance of grinding vehicle has an important meaning for increasing the stability in the grinding process.The dynamic model of grinding vehicle with the contact between the grinding wheel and rail was established by means of multi-body system dynamic software SIMPACK. The curve negotiation performance of both single vehicle and three-marshalling vehicles under the free running and grinding operation conditions were analyzed in detail. The influence of track irregularity and grinding vehicle’s suspension parameter on the grinding pressure fluctuation were investigated. For the rail asymmetric grinding, the influence of grinding different position of rail on the vehicle’s dynamic performance was explored.Main conclusions are drawn as follows.(1) With curve radius increasing, the derailment coefficient and wheel load reduction rate of grinding vehicle decrease under the free running and grinding conditions. A larger curve radius causes a smaller centrifugal force on vehicle, and then the remaining centripetal force increases. Therefore, the lateral wheelset force increases with an increase in curve radius. The increase of curve superelevation always has a negative effect on the dynamic performance of grinding vehicle, because the vehicle always operates in the surplus superelevation condition.(2) The dynamic behavior of there-marshalling grinding vehicles is complex owing to the joint and constraint force between each grinding vehicle. The greater curve superelevation results in the worse dynamic performance of marshalling vehicles. All dynamic indexes of grinding vehicles under the free running condition are superior to the grinding condition.(3) Setting the vertical positioning stiffness to 50 MN/m and the suspension lateral span to 1.8 m, the dynamic performance of grinding vehicle is best considering the derailment coefficient, wheel/rail lateral force and wheelset yaw angle. The anti-rotation stiffness between each vehicle has a negative and positive influence on dynamic performance. Setting the anti-yaw stiffness to 0.2-0.3 MN/rad and anti-nodding stiffness to 15-16 MN/rad, the dynamic performance of grinding vehicle reaches an optimization.(4) With an increase in the irregularity wavelength of track, the pressure fluctuation amplitude increases by a inverse function. With the irregularity amplitude increasing, the pressure fluctuation amplitude linearly increases. Rail corrugation may cause the resonance of grinding vehicle’s key parts, the rolling vibration, vertical vibration and nodding vibration of cradle frame producing large vertical relative displacement between the grinding wheel and rail, which led to a significant pressure fluctuation.(5) The lightweight of grinding mechanism is benefit to reducing the pressure fluctuation in the grinding process. With the vertical positioning stiffness of primary suspension increasing, the grinding pressure firstly decreases and then increases. Setting the vertical positioning stiffness to 28 MN/m is helpful to reducing the pressure fluctuation.(6) By analyzing the different grinding position on the inside, outside and top of rail, when grinding the inside of upper rail and outside of lower rail, the dynamic performance of grinding vehicle is best. However, grinding the outside of upper rail and inside of lower rail results in the worst dynamic performance of grinding vehicle.