Research On Unsteady Process Of Belt Conveyor Based On Wave Analysis Method

Belt conveyor has become the most important bulk materials continuous conveying equipment and been widely used in metallurgy, mining, port and food industries. The dynamic characters become much more important for large loading capacity, long distance and high velocity belt conveyors. It’s difficult to resolve the dynamic characters of the belt conveyors in the complex working condition by analytical method. The FEM method becomes complicated when resolving the dynamic characters and it can’t be used to control the conveyor in real-time. In fact, the velocity and tension wave propagation in the belt. And it’s close to the nature of the belt’s dynamics to use wave analysis method. The wave analysis method just concludes wave superposition and the computation complexity is lower. It’s easy to realize the real-time control of the belt conveyor.The paper built the viscoelastic wave equation of the belt. The attenuation coefficient and wave velocity were derived by analyzing the harmonic solution of the wave equation and it studied the relations between the frequency and them. The effect of dispersion can be neglected but the absorption can’t be neglected.The paper studied the impendence relation between the velocity waves and tension waves. It studied the excitation model of the driving pulley. The relations between the reflection waves, refraction waves and incident waves of the changing direction pulley were studied. It built the waves propagation model in the conveying lines by analyzing the boundary conditions.The paper studied the propagation of the waves in the circle conveying lines. The belt was flexible body and its flexural torque was neglected. And the principles of the waving propagation in the straight lines and circle lines were same. It got the viscous time constant and dummy acceleration of the circle lines of the belt. The paper built the waves model of the take-up pulley. It studied the reflection waves and refraction waves of the incident waves at the take-up pulley. The waves would totally reflect at the pulley when the conveyor was in steady state. The control strategy of the conveyor was studied. To increase a motor or to increase head pulley mass or decrease tail pulley mass can reduce the tension of the belt. The paper studied the stop process of the belt. The initial parameters of the stop process can be deduced by the conclusion of the wave reflection totally at the take-up pulley. It built the second dynamic model of the stop process of the belt conveyor and analyzed the stop process after the pattern of the start-up process.It studied the arithmetic of the wave method and got the programs by Matlab. The paper simulated the belt conveyor with a head driving pulley and a tail changing direction pulley in simple working condition to validate the rationality of wave analysis method. And the simulation results validate that the method is rational. A complex long belt conveyor was simulated and the results were same with the theory calculation. And it got the tensions and velocities distribution of the belt in unsteady process. The wave analysis method can be used to control the complex belt conveyor in real-time.