Modelling the Dynamics of Coal and Mineral Cutting

Abstract

A dynamic model is developed for coal and mineral cutting machines which exhibits all their important behavioural characteristics. In particular, the model produces the characteristic hopping motion observed in practice to take place at frequencies closely related to the speed of rotation of the cutting head. The low-frequency instability of simple, integral load-control systems is also verified by simulation.

Frequency-response analysis is shown to predict the practically observed and simulated system behaviour. the analysis necessitating a describing-function approach to the modelling of stick/slip effects in the machine haulage system, which are shown to exercise an important control on the limit-cycling of the regenerative cutting dynamics. The analysis is shown to be applicable to systems using both conventional haulage (feed) systems of low stiffness, and also to stiff transmission systems.

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