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Dynamic model of a roadheader's cutting system which incorporates transverse cutter heads |
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Dynamic model of a roadheader's cutting system which incorporates transverse cutter heads Authors: M. Dolipski, P. Cheluszka
A dynamie model of a cutting system of the roadheader provided with transverse cutter heads covers its physical model and its mathematical model. For the purpose of physical and mathematical modelling of a roadheader's cutting system eight groups of factor which are likely to influence the dynamic load in the cutting system have been taken into account. The roadheader's cutting system is composed of an asynchronous motor, a flexible coupling, a toothed (reduction) gear and cutter heads. This is a complex system characterized by a continuous distribution of the mass with its concentration being visible in such elements as: a rotor of the driving motor, disks of the flexible coupling, gear wheels and cutter heads. Such a construction of the cutting system is conducive for working out a physical model of discrete type. Thus, it comprises rotating concentrated masses with / moments of inertia connected one with another through weightless viscoelastic elements characterized by specific torsional rigidity k and damping coefficient c. The moment of load forces on a shaft of a cutter head makes forcing of torsional vibration. This is an effect of action of a roadheader on the rock mass when cutting a face of the heading or room being driven. The load of a cutter head is equal to the sum of loads on particular cutting tools engaged in the process of mining the rock at the same time. Recognition of the physical essance of the process of mining the rock in the course of particular movements of a boom and modelling of cuts taken by conical cutting tools of the cutter head are the starting point for determining the run of such forcing. A detailed kinematic analysis of a transverse cutter head was carried out with this objective. Three basic movements of the boom i.e. its swinging in the plane parallel to the floor, its swinging in the plane perpendicular to the floor and displacement of the boom in direction parallel to the longitudinal axis of a heading being driven have been taken into account. As regards cutter heads three basic types of cuts taken by cutting tools have been distinguished and namely: an opening cut, half-opened cut and opened cut. A method of modelling the cuts taken by conical cutting tools loading to determining the course of depth of cuts taken has been presented. This mates the basis for determining the course of loading of cutting tools and finally the course of a moment of load forces on a shaft of the cutter head. A mathematical model is a result of formalization of dynamic phenomena occurring in the physical model. It makes a set of relations of dynamic phenomena occurring In one physical model. Equations relations describing the motion in the physical model. Equations of motion in the physical model of a cutting system have been formulated under application of the Lagrange equation of the second order. A nonlinear system of ordinary differential equations of the second order has been obtained in this "way. Trie developed dyrrarrflt model made W possible to investigate dynamic phenomena occurring in a roadheader's cutting system.
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2011