Mechanics of rubber covered conveyor rollers

Conveyors consist of rubber coated, fiber reinforced belts which are supported and driven by rollers. The rollers are generally rubber coated. This coating (or lagging) is deformed by the pressure of the belt onto it. The pressure onto the lagging is constant over the contact area. The deformations resulting from this mode of loading have been modeled, taking also into account slippage between the rubber and the plates and compressibility of the rubber. The constant external pressure is counter-balanced by a compressive force and an internal hydrostatic pressure in the rubber. Since the internal pressure has a maximum in the center of the block, the compressive deformation is highest at the edges where the rubber can bulge the most. Closed form solutions of differential equations are presented. Slip between the belt and the rubber is proportional to the pressure. Predictions are in good agreement with experimental data. Additional slip arises from troughing transitions, uneven belts and rollers and from driving forces. Abrasion due to slip is proportional to the pressure of the belt to the power 1.5 to 3. Equations to predict abrasion are presented. To reduce abrasion rate, conveyors should have higher diameter rollers, low belt tension and a wider belt. Also, cylindrically machined pulleys, high quality belts and long troughing transitions should be employed.