Research On Performance Optimization Of Draft Gear Device On Railway Freight Car

With the continuous development of railway freight car technology towards the goal of speed and heavy haul,ensuring the efficiency of transportation while ensuring the safety of train operation is a top priority.Draft gear device is the basic equipment of railway freight cars.It is a mechanical device that relieves longitudinal forces between vehicles,absorbs kinetic energy of impact,and reduces vibration between vehicles.Its performance is the key to restrict the further improvement of the speed and load of railway freight cars.During the maintenance of railway freight car draft gear devices,problems such as severe surface wear of parts,seizure and seizure between parts are reflected.These phenomena are reflected in the train operation that both the longitudinal force between the vehicles is not well relieved,and the large coupler force causes the internal parts of the coupler to break or even the cracks of the coupler.The cracks caused a safety accident like a train to derail.Therefore,the design and research of draft gear devices are not only related to railway safety issues,but also related to the future development trend of railway freight car technology.This paper studies the predictable performance of railway freight car draft gear devices from the following four aspects:1 Analyze the structure of the draft gear device by deriving the theoretical characteristic formula of the draft gear,clearing that the friction coefficient is an important factor influencing the performance of the draft gear;analyze the cause of the rigid section of the draft gear,provide direction and focus for the subsequent research on the performance of the draft gear device.2.A dynamic simulation test of draft gear device is carried out based on the Recur Dyn multi-body dynamics simulation platform,the reliability of the draft gear model was verified by the drop weight test.Compared with the field experimental data,the test results of simulation model,the average error of the impedance is 1%;then the shunting operation test and the performance test of the draft gear device in the train operation are setting up,The performance curve of the draft gear displays a strongly relative to its internal friction coefficient.3.Aiming at the problems of serious wear,stress concentration,and insufficient reset occur in the draft gear device,a rigid-flexible multi-body dynamics analysis is carried out.The result of dynamic stress of cloud diagram showed that there was serious uneven distribution of contact force in the friction mechanism,and there was stress concentration inside the wedge and fixed inclined plate.The phenomenon may cause excessive wear between the friction parts;when the spring is subjected to dynamic stress,the inner stress of the coil is greater than the outer side,and the spring end and the effective coil are connected to the larger stress generated at the connection between the end and the support base.The contact force distribution on the contact surface of the cabinet is concentrated.4.Based on the Recur Dyn Auto Design module,the multi-objective design optimization of the friction mechanism of the draft gear device is carried out.The four friction surface parameters of the friction mechanism are used as design variables and the performance curve of the draft gear device is optimized.The design study experiments indicate that the dynamic and static friction coefficients of the friction surface of the wedge and the fixed inclined plate have a greater impact on the performance of the draft gear.The parameter combination of the optimized model is obtained by Discrete Latin Hypercube Design and Simultaneous Kriging Method The simulation experiment results show that the impedance characteristic curve has been significantly improved,the maximum impedance force has decreased by 11.53%,and the stroke has increased.2.5%;this optimization result also improves the problems of stress and contact force concentration between internal parts of the friction mechanism of the Draft gear device.For the first time,the thesis uses multi-body dynamics simulation technology to study the performance prediction of railway freight car draft gears.The simulation model has been tested and verified,which provides a new technology for the optimal design of key complex components of railway vehicle products.