Structural Parameters Analysis Of Wedge Tpye Variable Friction Snubbing Device

Due to the increasing speed of railway freight and the improvement of heavy load technology,the load of heavy haul trucks in China has been gradually increased to the level of 80t,the new freight train to reach the 70t level,its walking department is equipped with variable friction wedge type snubbing device three piece bogies.Because of its simple structure,easy maintenance and low cost,wedge snubbing device is widely used in railway freight cars,which is one of the important parts of freight car bogies,but the research on the dynamics of wedge type snubbing device is still rare.In practical application,the friction angle ? of the main friction surface of the current variable friction wedge snubbing device is mainly zero.This has a certain gap with the existing research results of variable friction wedge snubbing device.We need to study clearly the variation of the shock absorber characteristics caused by variable friction wedge type snubbing device,and the change of the vehicle performance.To achieve the targeted system analysis of friction snubbing device performance.Based on the existing research,this paper makes a lot of theoretical analysis and simulation analysis of wedge type snubbing device,which provides a theoretical basis for developing wedge snubbing device of large axle heavy bogie.In order to solve this problem,the author makes a detailed theoretical analysis from three angles of displacement relation,mechanical relation and work relationship.The correlation expression is deduced,and it is pointed out that the main frictional angle ? of the variable friction wedge snubbing device is greater than zero,equal to zero and less than zero,respectively corresponding to three different mechanical relations,and points out the corresponding locking interval in three cases.At the same time,the relationship between the friction angle of the principal and the vice and the friction force is investigated by analyzing the proportional relation between the friction and the upward and the downward frictional forces in each relationship.Based on the Simpack Dynamics software,a vehicle dynamics model of a freight car is established.The analysis results of the relationship between the main and the friction angle and the friction force are simulated,and the simulation results are consistent with the theoretical analysis results.The model is used to consider both full load and unload condition,the influence of the parameters of wedge snubbing device(including:main friction angle ?,vice friction angle a,friction coefficient ? and wedge damping spring stiffness k)on the vertical and transverse stability of the vehicle under the action of track irregularity is analyzed.The research shows that when ? equals 0°,? take 0.25,a value is greater than 75.96°,friction locking interval in the downward working condition,the current wedge angle ? equals 0°,? equals 58° in safe operation interval.For the angle of improving the vehicle running stability,it is suggested that a should be taken in the interval of 48?58°,? should be taken in the interval of 0?1°,the smaller the value of ? in 0.15?0.45 interval,the better the smooth running of the vehicle,and the value of K in 250?350 N/mm interval.