Conveyor Belt - Stressed Condition Before Operation

A feature of conveyor belts is that from the very "beginning of birth" their elements are in a stressed state before they are put into operation.

The source of the stressed state of the elements of the conveyor belt are technological operations in the manufacture of tapes.

When assembling the core, the tension of the fabric pads is different, and the more their number, the greater the difference in the tension of the gaskets. When testing for rupture, the destruction of more "strung" gaskets takes place first, and then the rest.

At the same time, the conveyor belt loses its safety margin.

The non-simultaneous rupture of the gaskets leads to a reduction in the overall strength of the belts, while non-simultaneity increases even more in operation, ultimately reducing the margin of strength of the belts.

Therefore, it is not advisable to install "too" multi-layer tapes on responsible conveyors, it is more rational to choose ribbons of a smaller ply with more robust carcass fabrics.

When the squeegee (layer) is applied to the carcass fabric of the working and non-working (raw calender mixes) of the plates and sides during the manufacturing of the belts, there are also (and mostly remain) stresses in the tape elements.

At the final stage - vulcanization, these stresses are partially reduced, and partially "fixed", especially when drawing and pressing workpieces in the press.

The presence of residual stresses can easily be determined visually. So, for example, if you peel the sample of the working pad "especially thick" from the frame and then apply it again to the cutout site, you can see its noticeable shortening (ie, before the detachment the cover is in the "stretched" state).

The rubber board, cut off from the core, acquires a pronounced crescent, indicating the presence of residual stresses.

This phenomenon should be taken into account when repairing and operating tapes.

So, for example, when repairing the "bubbles" of the working lining after vulcanization, it is necessary to peel it off with a much larger area than the "bubble" itself and then impose a patch. Otherwise, in operation, "peeling" the places of factory repair of "bubbles" and the gradual destruction of this zone.

When abrasion of a portion of one of the sides of the belts in use and the impossibility of its rapid repair, it is recommended to gently cut the opposite side of the bead in order to exclude the appearance of sickle-shaped and de-centered tapes.

In practice, there is often a need for emergency replacement of a destroyed section of belts. At the same time, due to the lack of sufficient stock, they sometimes have to cut their wider ribbons into narrower billets. In such cases, pruning is recommended to be carried out from both sides (along the width) of the sides of the belts in order to exclude the possible sickness of the resulting blank.

In operation, longitudinal and transverse cut-through cuts of the belts often occur when foreign objects enter the cargo stream and become jammed in the loading device. If the cut through location is not quickly repaired, it is "trying" to fold into the pipe due to the presence of residual stresses. Repair of such damages is complicated, and sometimes ineffective.

Thus, the phenomena of residual stresses must be taken into account when repairing and operating tapes. The conveyor belt is the main element of the conveyor, therefore its durability determines the reliability of the conveyor.