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    Abstract   Cone crushers are used in the aggregates and mining industries to crush rock material. A model to predict the worn geometry of cone crushers was previously developed. In that model there was some disagreements between predicted and measured geometry and several effects were suggested to explain the discrepancy in the model. In this study the effect of shear forces along the crushing surfaces was implemented in the model. Simulations were compared to measurements on two different crushing chambers. The results show a significant improvement with respect to the discrepancy between measured and simulated geometry. Measurements were made on a coarse crushing chamber where the operating parameters hydroset pressure, power draw and capacity were tracked during the lifetime of the set of liners. The simulated operating parameters show some agreement with measured data, but the crusher was not run under ideal conditions at all times. 43856

    1.Introduction                                                                    

          Cone crushers are widely used in the mining and aggregates industry to crush blasted rock material. The two main crushing parts are the mantle and the concave.  The main shaft of the mantle is suspended on a spherical radial bearing at the top and in an eccentric at the bottom. A hydraulic cylinder supports the thrust bearing that carries the thrust force of the main shaft. The hydraulic system can raise the main shaft in order to compensate for the wear of the mantle and concave. 

    The hydraulic pressure in the cylinder that supports the thrust force from the main shaft is called the hydroset pressure. As the eccentric is turned the rock material will be squeezed and crushed between the liners  (see Figs. 1–4).  

     Along its path through the crushing chamber, a rock particle will be subjected to several crushing events. The shortest distance across the crushing chamber is called the closed side setting, CSS, and is an important variable for the performance of the crusher. The control system is calibrated regularly to maintain a constant CSS. Previous research has made it possible to model the behaviour of a given cone crusher. Evertsson developed a flow model, a size reduction model and a pressure response model.

         The geometry of the crushing chamber is crucial for the performance. Due to wear the geometry of the liners will change,and hence the crusher performance will also change and sometimes suffer. Therefore it is desirable to simulate the change of geometry and performance as the liners wear. A model for this purpose was previously developed . That model was based on the results of Evertsson . In the model for wear prediction there was some discrepancy between the simulated geometry and measured geometry in the upper part of the crushing chamber. Several explanations of this discrepancy were suggested.It was first assumed that the work hardening behaviour of the liner material might depend on the applied pressure. In a study  by the author  it was concluded that it was not a variation in work hardening in the chamber that caused the discrepancy in the wear model.

     Among the other explanations for the discrepancy, that were proposed  by  Lindqvist and Evertsson,the prediction of pressure on the liners  was  assumed  to  be an important factor.  To address this, an improved flow and  pressure  model was  presented by Lindqvist and Evertsson. That model showed a significant improvement  in prediction of the operating parameters CSS,power draw and capacity, but only a  slight improvement of wear prediction for a fine crushing chamber.

     Other suggested explanations are  non-linear dependency  between pressure and wear, shear stress at the interface between  rock and liner, dependency between particle size and wear rate.  Chenje and Radziszewski showed that there was a non-linear  relationship between applied force and wear rate in a sliding  wear experiment. If Chenje’s   results were also applicable  for the case of non-sliding wear in cone crushers, they would, at  least in part, explain the discrepancy. The technique used in the present study, to measure the geometry of the liners, is similar to the technique used by Rosario . He has made measurements of liner wear on gyratory crushers.

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