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Shock and Vibration
Volume 2016 (2016), Article ID 4028583, 7 pages
http://dx.doi.org/10.1155/2016/4028583
Research Article

Nonlinear Model of Vibrating Screen to Determine Permissible Spring Deterioration for Proper Separation

Department of Mechanical Engineering, University of Concepcion, Edmundo Larenas 219, 4070409 Concepcion, Chile

Received 4 March 2016; Revised 2 August 2016; Accepted 8 August 2016

Academic Editor: Samuel da Silva

Copyright © 2016 Cristian G. Rodriguez et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Springs of vibrating screens are prone to fatigue induced failure because they operate in a heavy duty environment, with abrasive dust and under heavy cyclic loads. If a spring breaks, the stiffness at supporting positions changes, and therefore the amplitude of motion and the static and dynamic angular inclination of deck motion also change. This change in the amplitude and in the inclination of motion produces a reduction in separation efficiency. Available models are useful to determine motion under nominal operating conditions when angular displacement is not significant. However in practice there is significant angular motion during startup, during shutdown, or under off-design operating conditions. In this article, a two-dimensional three-degree-of-freedom nonlinear model that considers significant angular motion and damping is developed. The proposed model allows the prediction of vibrating screen behavior when there is a reduction in spring stiffness. Making use of this model for an actual vibrating screen in operation in industry has permitted determining a limit for spring’s failure before separation efficiency is affected. This information is of practical value for operation and maintenance staff helping to determine whether or not it is necessary to change springs, and hence optimizing stoppage time.