Research On The Mechanism Of Friction Self-Excited Vibration Of Coke Pushing Device

Complete set of equipment for 6.25 m tamping coke oven is an advanced mechanical equipment widely used in coking production.The use of the equipment has obvious economic and social benefits for improving the yield of the coke,reducing the energy consumption and the emission of the pollutants.The coke pushing device is the core component of the complete set of equipment,and there is obvious vibration phenomenon in the process of using it.The vibration will not only affect the normal operation and use of the coke pushing equipment,but also lead to the collapse of coke cake,and even result in equipment shutdown and unable to work.Therefore,it is of great theoretical and engineering application value to deeply study the vibration mechanism of coke pushing device in order to reduce the vibration of the device.There will be strong friction between the coke pushing device and the ground of the carbonation chamber during the working process,which has an important influence on the vibration of the device.Through the analysis of the vibration characteristics of the coke pushing device over the years,it is found that there are obvious sliding vibration and flutter phenomena in the working process of the coke pushing device,which accords with the typical characteristics of the friction self-excited vibration.It can be seen that the main vibration type of the coke pushing device is the self-excited vibration caused by friction.However,no scholars have specially studied the vibration characteristics of the coke pushing device by establishing a friction model.In this paper,the dynamic model of the coke pushing system is established.The self-excited vibration mechanism of coke pushing device is studied by theoretical calculation,simulation analysis and field test.The main research contents are as follows:The mechanical model of the coke pushing self-excited vibration system based on Stribeck friction effect is established through deeply studying the friction model based on Stribeck effect,and combining with the actual structural characteristics of the coke pushing system,which lays a theoretical foundation for the further study of the self-excited vibration mechanism of the coke pushing device and the stability and stick-slip motion characteristics of the coke pushing system.In this paper,Lyapunov stability theory is introduced into the stability analysis of the coke pushing system,the critical instability velocity of coke pushing system is solved,and the stability of the coke pushing system is analyzed.The phase-plane plots and Poincare sectional views of the coke pushing device with different system parameters are obtained through the simulation and analysis of the dynamic equations of the coke pushing system.The results show that,the system gradually reaches the asymptotic stability state from the unstable state with the increase of the driving speed and the damping of the system.When the mass of the coke pushing device and the equivalent rigidity along the x-axis are increased,the system gradually reaches the stable state from the unstable state.The stability of the system is enhanced by increasing the equivalent stiffness along the y-axis and decreasing the difference between dynamic and static friction coefficients.The effects of driving speed,stiffness,damping and friction coefficient on the stick-slip motion of the coke pushing device are studied by means of multi-body dynamic simulation analysis.The results of the velocity and acceleration response curves of coke pushing device with different system parameters show that increasing driving speed is an effective way to reduce stick-slip motion,increasing stiffness k₃and system damping can reduce the occurrence of stick-slip motion,increasing stiffness k₁ and k₂ will increase the possibility of stick-slip motion,and reducing the difference of dynamic and static friction coefficients is not conducive to reducing the phenomenon of stick-slip motion of the coke pushing device.The stick-slip vibration characteristics of the coke pushing device are studied by the method of finite element simulation.Through the modal analysis of the coke pushing device,it is found that the large parts of the deformation are mainly concentrated in three areas,namely the pushing rod,the pushing head and the slipper.The low-frequency vibration with the frequency of 51 Hz is found in all the traveling direction,the vertical direction and the transverse direction by the harmonic response analysis of the coke pushing device.The vibration frequency is the same as the 14th order mode in the modal analysis.The main vibration form of the coke pushing device is the bending vibration in the vertical direction,and the large deformation area is mainly concentrated in the tail of the coke pushing rod.In order to extract the self-excited vibration frequency of the coke pushing device under actual working conditions and verify the finite element simulation results,a new improved algorithm in this paper is proposed on the basis of emd algorithm,and the vibration signal in the operation process of coke pushing device is analyzed by using this algorithm.The frequency of self-excited vibration of coke pushing device is extracted and compared with the simulation analysis.It is found that the results of experimental analysis and simulation analysis are basically consistent,which proves the effectiveness of the simulation analysis method.