Study On Vibration Characteristics And Vibration Mechanism Of Coke Pushing Rod

Coke oven production is an important basis for the comprehensive utilization of coal,plays an important role within the metallurgical industry,occupying an extremely important position in economic operation.However,the vibration problem of the coke pushing rod during the coke pushing process not only affects the normal production of coke oven,the working life of coke pushing equipment,but even causes the coke cake collapsed.Therefore,it is necessary to find out the vibration cause of the coke pushing rod.In view of the fact that the vibration cause of the coke pushing rod has not been systematically studied,this paper studies the vibration characteristics and vibration mechanism of the coke pushing rod via theoretical research,simulation analysis and test verification,thus finding out the fundamental cause of the vibration of the coke pushing rod,providing a theoretical basis for the vibration reduction measures.The main contents of this paper are as follows:(1)The working characteristics and force condition of the coke pushing rod during the coke pushing process are analyzed.The coke pushing resistance of different displacement sections is deduced via the variation of the coke pushing current,and the vibration mechanics model of the coke pushing rod during the cok pushing process are established.Via theoretical study,the critical velocity of the vibration of the coke pushing rod is deduced.Combining with the working characteristics of the coke pushing rod,it is concluded that the vibration of the coke pushing rod mainly occurs after the slipper enters the carbonization chamber and the contact friction between the bottom of the slipper and the ground of the carbonization chamber occurs,the higher difference between static and dynamic friction coefficients between the contact surfaces is the fundamental cause for the vibration of the coke pushing rod.(2)The influence of the difference between the static and dynamic friction coefficients,stiffness and damping on the stability of the coke pushing rod is analyzed by structural dynamic simulation.It is found that the difference of the static and dynamic friction coefficients has the greatest influence on the vibration of the coke pushing rod,and when the coke pushing rod is not affected by friction,it runs stably without obvious vibration.After the action of friction,the coke pushing rod vibrates violently.It is indicated that the difference between the static and dynamic friction coefficients is the fundamental cause of for the vibration of the coke pushing rod,validating the conclusion of the theoretical analysis.In order to analyze the vibration characteristics of the coke pushing rod,the modal analysis for the structure of the coke pushing rod is carried out,and the low-frequency vibration frequencies.(3)By means of Fourier transform,short-time Fourier transform,Heirbert-Huang transform based on empirical mode decomposition(EMD)and complex Morlet continuous wavelet transform,time frequency analysis of the vibration signals of the coke pushing rod respectively,it is found that the signals have better time-frequency resolution after the short-time Fourier transform,and the vibration frequency-time-amplitude information of the signals can be extracted more accurately.The results of time-domain and time-frequency analysis show that the vibration of the coke pushing rod mainly occurs after the slipper enters the carbonization chamber,and the self-excited vibration of the coke pushing rod occurs due to the drastic variation of friction,which verifies the conclusion of the theoretical analysis.(4)During the coke pushing process,there is a 4.5cm gap between the coke pushing head and the ground of the carbonization chamber,so a very small amount of coke has not been pushed out of the carbonization chamber,and the powder is formed under the action of pressure,thereby,a three-body friction contact surface is formed between the bottom of the slipper,the coke powder and the ground of the carbonization chamber(refractory brick).In order to further clarify the relationship between contact friction and vibration,the friction characteristics of three-body contact surface formed by steel,coke powder and refractory bricks are studied by the friction tests,and the micro-mechanism of the contact surface and the influence of coke particles on the contact surface were revealed.The necessary relationship among the lubrication state of friction surface,friction coefficient and vibration is further revealed.Thus,the conclusion of theoretical analysis is verified that the higher difference between static and dynamic friction coefficients is the fundamental cause for the vibration of the coke pushing rod.