Determination of critical inclination angle for the conveyer with pressure belt

Abstract

Today , steeply inclined belt conveyors with pressure belt are widely used in the world for transporting bulks. According to the literature, critical angle of these conveyors inclination varies from 35º to 90º. However, there is no sufficiently justified value of critical conveyor inclination angle. In this work, critical inclination angle of conveyor with pressure belt was determined for different states of the bulk on the conveyor depending on linear load of the bulk on the conveyor belt and the bulk properties. It was assumed that tangential stresses at each point of the bulk were balanced by the bulk gravity force projected towards the direction of conveyor belt movement and did not exceed critical tangential stresses in the bulk medium. In addition, the Coulomb's law of friction was applied for the forces of the bulk friction against the conveyor carrying and pressure belts. In this article, the authors consider cases when coefficient of the bulk internal friction is greater than coefficients of the bulk friction against conveyor carrying and pressure belts, and when coefficient of the bulk internal friction is less than coefficient of the bulk friction against the conveyor carrying belt. As a result of solving the obtained systems of the equilibrium equations for each of the above cases, the dependences of critical inclination angle of conveyor with pressure belt on the linear load of the bulk and linear weight of the pressure belt, as well as on coefficients of the bulk friction against the carrying and pressure conveyor belts and coefficient of the bulk internal friction load were determined. Analysis of the obtained dependencies showed that critical inclination angle of conveyor with pressure belt decreases with increase of linear load of the transported bulk. With an increase of coefficients of bulk friction against the conveyor carrying and pressure belts and coefficient of the bulk internal friction, critical inclination angle of conveyor with pressure belt increases. Besides, with increase of ratio between the pressure belt linear load and the bulk linear load, critical inclination angle of conveyor with pressure belt increases and tends to 90° when increase of this ratio is unlimited.