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The image below shows an eyelink, plate link and cross rods.
The following materials are used for Twentebelt eyelink conveyor belts:
Other materials are available on demand and/or on advice.
Twentebelt offers a variety of eyelink belts. Click on a belt type to learn more.
Twentebelt offers 4 different side finishes for its eyelink conveyor belts.
1 – Pitch: Centre-to-centre distance of cross rods (ranging from 15,9 to 76,2 mm)
2 – Cross pitch: Centre-to-centre distance of eyelinks (ranging from 2,8 to 50 mm)
3 – Wire diameter (ranging from 1,6 to 3,2 mm)
4 – Number of location wires (ranging from 0 to 8)
Explanation of specification method for eyelink belts. For example: DL-LK 6 – 50 – 2,5 – 5 location wires 1
DL-LK: Welded eyelinks with welded edges
6: Cross-pitch (mm)
50: Pitch (mm)
2,5: Wire diameter (mm)
5: Cross bar wire diameter (mm)
| Pitch (mm) | Wire diameter | Cross rod diameter | Minimal centre-to-centre distance between 2 eyelinks | Minimal centre-to-centre distance between 2 eyelinks in welded version |
|---|---|---|---|---|
| 15,9 | 1,8 | 3,2 | 3,6 | Not applicable |
| 25,4 | 1,6 | 5 | 3,2 | 3,25 |
| 2 | 4 | 3* | ||
| 30 | 1,6 | 4 | 3,2 | 3,25 |
| 2 | 4 | 4,05 | ||
| 38,1 | 2 | 8 | 4 | 4,05 |
| 2,5 | 5 | 5,05 | ||
| 3 | 6 | 6,05 | ||
| 50 | 1,6 | 5 | 3,2 | 3,25 |
| 2 | 5 | 4 | 3* | |
| 2,5 | 5-7 | 5 | 5,05 | |
| 3,2 | 6 | 6,4 | 6,45 | |
| 50,8 | 2 | 5-8 | 4 | 3* |
| 2,5 | 5-8 | 5 | 5,05 | |
| 3 | 8 | 6 | 6,05 | |
| 75 | 2,5 | 5-8 | 5 | 5,05 |
| 3 | 8-10 | 6 | 6,05 | |
| 76,2 | 3 | 10-13 | Not applicable | 6,05 |
Generally two configurations are possible to provide eyelink belts with support: longitudinal support or herringbone support.
Longitudinal support for eyelink belts
The longitudinal support consists of support sections fitted in the longitudinal direction of the installation. These sections are placed at both sides and depending on the width and the load, about every 300 mm right across the width of the belt (see drawing). At the height of those support sections, rows of plate links must be fixed, which will convey the load to the underlying support sections. Depending on the load these rows will consists of one or more plates.
Herringbone support for eyelink belts
In a herringbone support structure the support sections (as the name suggests and the drawing illustrates) are positioned in the form of a fish bone. In this case it will be sufficient to place rows of plate links at the edges only. The bearing function will be taken over by the eyelinks. As all eyelink hit the support strips some time or other, the wearing pattern will be equally spread across the full width of the belt. With this support the product will be equally processed across the full width of the belt. Possible shadow zones, as is the case in longitudinal support structures, will not occur here.
If hygine is even a more important issue than usual, we advise you to provide the belt with plate links at the edges only. Because of their round shape eyelinks are easier to clean than plate links. In such a construction the frame will be constructed with a herringbone support, so that filth falling through the belt will immediately be pushed away from the support strips.
Support return path
The return path only carries the weight of the belt. This is why a lighter support structure is sufficient here. In the longitudinal construction one of two profiles can be left out. The herringbone support can be executed in a less compact form. In the return path, the first 500 mm of the belt slacken. There is no support in order to make the formation of a sag possible. The formation of a sag will prevent the belt from climbing on to the drive. It is also necessary in order to prevent the belt from being pushed instead of pulled through the return path. At both ends the support sections should be slightly bent down, in order to establish a gradually guidance of the belt on to and off the profiles.
Rollers can also serve as a support to restrict the frictional coeffecient. The rollers must be at right angles to the frame, parallel to each other and level. The distance between the rollers is irregular, in order to prevent an irregular run.
Frictional coefficient
Below you will find an indication of the frictional coefficient for the different alternatives:
Side guidance is achieved by vertical profiles at both sides of the installation. These profiles should not get in contact with the belt. They are meant to guide the belt in case it deviates from the carrying path. A clearance of 5 to 10 mm between the profiles and the belt is basically sufficient. The geometry of the frame and the load of the belt are points of attention in the design and the adjustment of the installation, because these factors can influence the run of the belt.
The minimal facility at the input side consists of profiles both on top and on the underside, at the discharge side, however, only on top. The maximal facility consists of profiles over the full length of the carrying path and the return path with the exception of the sagging part. The compromise is the placement of profiles of 300 to 500 mm length every 2000 mm. The appropriate configuration is also determined by the speed, the length, the width and the load of the belt. In case of doubt, please do not hesitate to contact us. We will be pleased to think along with you.
Sprockets
Generally, eyelink conveyor belts are driven directly on the eyelinks by means of specially developed drive sprockets. For DO belts these sprockets are provided with block teeth. In the case of DL belts the sprockets are constructed such that they exactly match the profiles at the underside of the belt. In case of belts with a large cross pitch (centre-to-centre distance of eyelinks) one could consider to place sprockets that are directly driven on the cross rod instead of on the eyelinks. Generally the sprockets are placed at both sides and under each row of plate links. The width, the number of teeth and the material of the sprockets are determined on the basis of the conditions of use.
When a construction of drive sprockets is applied in a freezer, sprockets with special toothing are used. In order to prevent the accumulation of ice, the so-called ‘ice-crusher’ sprockets are used. The special toothing limits the accumulation of ice to the minimum.
Sprockets are available in steel, AISI 304 (WS 1.4301), AISI 316 (WS 1.4401), PA6G and POM, or in other materials on request or on advice. An example of a stainless steel sprocket is featured below.
Cage rollers
Broad and heavily loaded eyelink conveyor belts are preferably driven by rollers right across the width of the belt, cage rollers in most of the cases. The straps of the roller regularly drive all the eyelinks of the pitch, which is conducive to a longer life span of the belt and also leads to a regular wear pattern.
Disc rollers
If there is a risk of accumulation of filth or ice, disc rollers should preferably be used. On a multiple of the cross pitch these rollers are provided with discs. These discs can be produced in different ways, so that different properties can be created:
Chain sprockets
Eyelink belts can also be produced with chains, whereby the chain fulfils a driving function. Especially when the belt has to perform a negative bend, as is the case with many applications for freezing or blanching, and for ascending belts. In those applications the side-sprockets are replaced by chain sprockets belonging to the chain applied.
In this case, too, the rule applies that for bigger constructions chain sprockets will be placed in combination with a roller.
In all applications with chains a negative bend of the belt can easily be achieved by means of chain sprockets or wear strips of the hollow pin roller chain. Twentebelt prefers the use of sprockets with at least 12 teeth. This is based on the fact that with this number of teeth the so-called polygon effect will exert hardly any influence on the belt run. If the length and the load of the belt are moderate drive sprockets with a minimum of 8 teeth might be used. The ultimate determination of the necessary number of teeth depends on factors like width, length, load and running speed of the belt.
As for the return shaft there is a choice between toothed or smooth wheels or rollers. In principle, toothing only has a function in case of accumulation of ice or filth. Toothing on the return shaft consequently has no drive function. Generally, in small installations one prefers to provide the return shaft with toothed wheels. When, however, a cage roller was chosen to drive the belt, a smooth roller will be chosen for the return shaft. An exception to this is a drive with cage rollers and chain wheels, whereby the same construction is used as a return roller.
If provided with one tooth per pitch the rollers are one-directional and thus only to be used for drive or for return. Rollers with double strips can be used for both drive and return, if the installation is designed for this purpose.
Of course, this depends on the length and the load. In general, the return shaft is the one for tensioning and adjustment. In case of short belts and insufficient geometry of the frame this can lead to a bad drive (see drawing below).
In most cases a screw tensioning device will suffice. An example of a screw tensioning device can be seen below.
In the case of a continuous tensioning device, hydraulic, pneumatic or with springs, there is always the risk of a certain amount of uncontrolled stretching that tends to elongate the belt. The table below provides the tensioning length per pitch. It has to be taken into account when the shaft has to be adjusted. The tensioning force = (the weight of the belt in the return part x the friction coefficient) x 9,8.
| Pitch | Tensioning length |
|---|---|
| 15,9 | 45 |
| 25,4 | 75 |
| 30 | 90 |
| 38,1 | 110 |
| 50/50,8 | 150 |
| 75/76,2 | 250 |
Please click on a subject below to learn more.
In case of negative bends of DL-type eyelink belts, a point concentrated load can occur in the zone of the location wire. As a result of repeated minimal bends the eyelinks can break. The use of special guidance strips with a wide radius offers a solution.
Below you will find downloads related to eyelink conveyor belts.
Twentebelt Eyelink conveyor belts – Technical brochure – English
Twentebelt Eyelink conveyor belts – Request quotation form – Dutch
Twentebelt Eyelink conveyor belts – Request quotation form – English
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