Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering
Transport Technology

W.J. Naaijkens Belt displacement in horizontal curves.
Computer program, Report 2003.TT.6779, Transport Technology.

This report provides the reader with an overview of currently used calculation methods for belt conveyor track with horizontal curves. Next it provides the description of a computer program formed to visualize belt displacement in the idler set, in these curves. This program can also show the forces acting on a side guide roll, should maximum belt displacement be exceeded.

The fundamental concept of a belt moving through a horizontal curve is very simple. As an element of the belt passes through the curve it is motivated to drift towards the center of the curve radius by unbalanced tension forces in the belt. These unbalanced tension forces form what is called the motivating force vector.
As the belt drifts laterally on the idlers, opposing forces induced by gravity and friction create increasing resistance to drift. These resisting forces form what has been termed the resisting force vector.
Since the motivating and resisting force vectors act in opposite directions, when their magnitudes become equal the belt will cease to drift. The belt has reached a condition of force equilibrium.
These calculations can be used to determine the belt drift, without physically constraining the edges of the belt. These equations are based on steady state conditions, so no dynamic behavior is involved.
If it were decided to constrain the belt at some limit of drift, the constraining force required is the difference between the motivating force and the resisting force at that limit.

The equations prescribing the equilibrium condition are used to form the algorithms for the computer program. With Maple 7.0, they have been reshaped to enable the program written in Visual Basic to calculate the displacement concerning different input conditions. The main input is loaded via a data file containing information on belt dynamics, and several parameters are to be defined by the user. The program consists of several interfaces; the main output is a graph showing the belt displacement in time.

A short look at the influence of the input parameters is given, followed by a main recommendation that in order to validate the output data, tests should be performed.

Reports on Transport Engineering (in Dutch)
Modified: 2003.07.14; , TU Delft / 3mE / TT / LT.