| As the key equipment of "three machine matching" in fully mechanized mining face,the performance of scraper conveyor has a direct impact on the efficiency and cost of underground coal mining.Due to the bad underground production environment,the abnormal load conditions of scraper conveyor can not be predicted and avoided,such as the sudden increase of materials on scraper chain,the conveyor chain is stuck,the excess residual materials on the no-load side are piled and squeezed to form a material bolt,and so on.When the scraper chain passes through the shearer,there are large pieces of materials jammed and unavoidable polygon effect.The abnormal load condition is easy to cause the tension and speed impact of scraper chain,resulting in the unstable operation of scraper conveyor,and serious will cause chain breakage,drive system failure and other disasters.Therefore,it is necessary to study the dynamic characteristics of scraper conveyor chain drive system under abnormal load.This paper mainly carried out the following research workFirstly,referring to the modeling method of multi-body dynamics and using the idea of finite element analysis,the finite element dynamic model of scraper conveyor based on Kelvin Vogit model is established,and the dynamic differential equation of scraper conveyor is derived;The static simulation software ANSYS Workbench is used to simulate the chain link of sprocket,and the stiffness coefficient of discrete element is obtained;The resistance of scraper conveyor is analyzed and calculated in detail.Then,the causes of scraper conveyor chain stuck and broken are analyzed,and the corresponding abnormal load excitation model is established;This paper analyzes the kinematic characteristics of the scraper conveyor,expounds the transmission law and stress characteristics of the chain drive system,and analyzes the polygon effect caused by the limited number of sprocket teeth in the chain drive process.It is concluded that the number of sprocket teeth and the chain pitch will have an impact on the stability of the scraper conveyor;Starting from the coal loading mechanism of shearer,this paper analyzes the influence of different coal loading methods on the offset load of scraper conveyor.Secondly,based on the finite element dynamic equation of the scraper conveyor,the dynamic characteristics of the scraper conveyor under abnormal load conditions are analyzed by using the numerical analysis software MATLAB to simulate the scraper conveyor's direct start-up,chain clamping and chain breaking at different positions,as well as the change of sprocket tooth number and chain pitch.Finally,in order to study the dynamic response of the specific meshing parts of the chain drive system under abnormal load conditions,a three-dimensional model of the chain drive system of the scraper conveyor is established.Based on the Adama simulation software,the influence of the sprocket polygon effect on the running stability of the scraper conveyor under different chain speeds and the change of the contact force of the sprocket chain link meshing under different chain speeds are analyzed in detail.The simulation results provide guidance for structural design and chain speed selection of scraper conveyor;In addition,the influence of different points of the chain on the indirect contact force and the speed of the chain link is simulated and analyzed.There are 82 figures,2 tables and 97 references in this thesis. |
PDF Full Text Request