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Large-scale belt-conveyor systems are extensively used in open mines to continuously transport bulk material. Conveyor pulleys are critical components and failures have significant financial consequences due to extended downtime. Aiming at increasing their durability, two critical spots are identified: the drum and the welds between end-plates and drum. Alternative designs have been evaluated. The paper aims to discuss these issues.

Loads on the driving drum are determined from measurements of the bearing force and the motor power. The friction interaction between belt and drum is described by the creep model and its impact is evaluated by comparing the results obtained for low and typical values of friction coefficient. Alternative designs are analysed using finite element method with optimised variable density mesh. The stress field and the deformations are calculated and evaluated.

Friction affects the torque transmission capacity and force distribution, but it is shown that in this case it has almost no impact on the maximum von Mises stress which occurs on the inside surface of the drum; therefore fatigue cracks initiated there, cannot be visually detected. A reinforcing diaphragm is added at the mid-plane to reduce the stress. A new, improved design is proposed to eliminate welds between the end-plates and the drum.

The new proposed design has to be tested in the field to ultimately validate its higher durability.

The impact of the friction of the belt on the drum is demonstrated. The reinforcement resulting from a mid-plane diaphragm is quantitatively evaluated and assessed. A new improved pulley design is proposed aiming at significantly increased operational life compared to the one of the current design.

The purpose of this paper is to introduce an alternative approach to the FE modelling and simulation of complex gear trains, such as the Wolfrom planetary system, in order to study their overload capacity. This is a challenging task because of the following: first, multiple contacts occur between complex geometric parts. Second, the model has to be solved for many instances in order to determine the relative position of the planetary system members at which the maximum bending stress and surface pressure occur. Third, the maximum allowable overloading torque has to be determined iteratively.

A Wolfrom planetary system with transmission ratio 19.2 is modelled and simulated using the finite element method. The optimum element size is selected by modelling and solving key areas of the system. Then, a complete model is built using balanced element length at the flanks and roots, with respect to low solution time and result accuracy. A single loading torque is applied at the input shaft and the load distribution results from the solution when equilibrium is achieved. The input torque is increased until the maximum allowable stress or pressure is reached.

Combining the load distribution derived from a mixed density mesh with Hertzian pressure calculations, improves the accuracy of the results and decreases the total evaluation time of overload conditions. Furthermore, meshing disturbances due to the elastic deformation of the matting tooth pairs can be identified. It is shown that in the Wolfrom reducer analysed, the limiting mode of failure is the tooth breakage, which occurs when the input torque is increased by a factor of 3.8.

The balanced element length meshing requires individually meshed key areas and additional workflow steps. In this way, the complexity is increased but the solution time minimised. Automation tools can improve the simulation process.

The balanced element length model and the result evaluation provides an improved approach of the overload capacity estimation where analytical methodologies cannot be applied.