GB2276363A - Conveyor belt - Google Patents

Abstract

A conveyor belt has flexible moulded cleats which retain produce during transport and which can adopt different relative orientations in response to flexing of the belt. <IMAGE>

Description

CONVEYOR BELT This invention relates to a conveyor belt. The belt may be used, for example, for the transport of fruit and vegetables, but the invention is not limited to this application.

Fruit and vegetables (produce) for human consumption, for example apples, potatoes or carrots, are commonly subjected to one or more processing stages before appearing on supermarket shelves. The processing stages may involve, for example, removal of clods of earth, grading by size, and/or washing.

Conveyor belts are commonly used to transport produce from one stage of the food production chain to another. For example, washed potatoes may be transported from a washing vat into a processing line by means of a conveyor belt driven by a rotating roller.

In order for the conveyor belt to retain the produce during transportation it is known to provide the belt with a plurality of elongate rubber cleats, or ribs, the long axes of each of which extend across the whole, or a substantial part, of the width of the belt. A problem with such a conveyor belt is that produce is liable to fall off the sides of the belt and be damaged.

Damaged to produce is also liable to occur if it falls from too great a height off the top of the conveyor belt.

Longitudinal bowing of the belt so that both outer edges are raised relative to the centre of the belt, known as "troughing", is a cheap and effective way of reducing losses of produce over the sides. Troughing, however, cannot be effectively employed with a belt with elongate cleats such as described above, because the elongate cleats act as belt stiffeners and resist bowing deformation.

An alternative which is known to the use of solid ribs is the use of rubber chevron structures which are symmetrical about the centre of the circumference of the belt. Belts with such chevrons permit some troughing, but in order to carry relatively large produce such as potatoes the chevron blocks need to be of substantial height normal to the local belt surface. The resulting increased mass resists being wrapped around a small diameter roller and therefore limits the minimum roller diameter with which it can be used.

Attempts to wrap a chevron belt around too small a diameter roller may cause fracturing of the chevrons. Use of a large diameter roller means that produce coming off the belt after its zenith have further to fall, increasing the likelihood of damage to the produce.

According to the present invention there is provided a conveyor belt, the belt having moulded onto its operational outside surface flexible cleats which are arranged to permit retention of conveyed materials, each cleat extending outwardly from the belt to define a cleat axis and having dimensions measured in a plane parallel with that of the belt, and including the cleat axis, all of which are substantially equal, the cleats being spaced far enough apart to permit the direction of orientation of one cleat axis relative to another to change if the belt is made to flex.

Reference to cleats having substantially equal dimensions in a plane parallel with that of the belt includes cleats which have such dimensions in the ratio of up to 2:1. Thus such cleats may for example be of circular, oval or square cross sectional shape.

It is not necessary that each cleat have a constant cross section along its axis, provided that it is flexible enough.

to resist damaging conveyed materials and sufficiently resilient to help retain the materials during transportation.

The cleats may be moulded individually onto the belt, or they may be connected by a flexible web.

The use of flexible, spaced-apart cleats to retain conveyed materials permits the belt to be troughed, and it also permits the belt to be driven by a relatively small diameter roller, thus helping to reduce the height that conveyed materials have to drop as they exit the conveyor belt, and therefore reducing the chance of their being damaged by the fall.

Preferably the belt and the cleats are made of rubber; it is particularly preferred that the cleats are made of natural rubber.

It is preferred that the cleats have a Shore hardness value in the range 35 to 70 degrees and, particularly, in the range 45 to 50 degrees.

Because the cleats are flexible they are unlikely significantly to damage materials that comes into contact with them. In order to reduce even further the likelihood of damage, it is preferred that the cleats do not present any sharp edges to the produce, and it is particularly preferred that the cleats be substantially circular in cross section parallel to the local plane of the belt.

The invention is particularly suited to the transportation of fruit and vegetables, which are susceptible to damage by dropping from a height or from knocking against hard objects. For use with such produce it is preferred that the cleats are 20 to 75 mm in height, and it is particularly preferred that they be 25 to 50 mm in height.

The spacing between individual cleats in a group may be of any distance which permits sufficient relative movement of the cleats to accommodate to bowing of the belt during troughing, and which is sufficiently small to prevent produce or materials from slipping between adjacent cleats in a group. A preferred spacing range is between 10 and 30 mm, and particularly between 15 and 25 mm.

The cleats may be grouped in any suitable orientation which permits retention of materials during transportation. A preferred arrangement of groups, which facilitates a relatively constant rate of delivery of materials to the exit point after the zenith, is for each group to comprise a linear array which extends perpendicularly from one edge of the belt between a point adjacent to that edge and a point in the region of the centre of the circumference of the belt, and adjacent groups alternately extending between alternate edges and the central region of the belt.

The invention also extends to a conveyor belt system comprising a drive roller and a belt as described above.

It is preferred that the ratio of drive roller diameter to cleat width is less than 10:1, and it is particularly preferred that the ratio is in the range 3:1 to 7:1.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a conveyor belt; Figure 2 is a plan view of a part of a conveyor belt according to the present invention; Figure 3 is a section on the line I - I of the conveyor belt shown in Figure 2; Figure 4 is a section of the conveyor belt shown in Figure 3 during troughing; Figure 5 is a plan view of a part of a conveyor belt in accordance with an alternative embodiment of the present invention; Figure 6 is a plan view of a part of a conveyor belt in accordance with a further alternative embodiment of the present invention.

Figure 1 shows a conveyor belt 2 for transporting produce into a receptacle 8. The belt 2 is driven by a roller 6 in the direction of the arrow 4. Produce drops off the belt 2 into the receptacle 8, and the height of this drop is determined by the diameter of the drive roller 6.

Figure 2 shows part of a conveyor belt 2 onto which is moulded groups of flexible rubber cleats 10, via a thin web 12. Two adjacent groups 14, 16 of cleats 10 present an effective restriction on the linear movement of produce in a direction parallel or antiparallel to the direction of travel 4 of the belt 2, provided that the gap (a) between cleats 10 is smaller than the smallest width of the produce.

Figure 3 shows the overlap between successive groups 14 and 16 of cleats lo, looking along the direction of travel of the belt 2.

Figure 4 shows how the cleats 10 can accommodate troughing of the belt 2 by adopting different relative orientations to relieve the stress induced by the troughing. When the conveyor belt 2 is troughed as shown in Figure 4 produce (not shown) tends to lie towards the centre of the belt 2 and, consequently, the risk of produce falling over the side of the belt 2 is reduced.

We have found that a belt as depicted in Figures 1 to 4, with natural rubber cleats 22 mm diameter and circular cross section, can readily be troughed to an included angle of 30*. The belt can be driven by a roller 6 of 100 mm diameter without cracking or splitting of the cleats. In contrast, a typical chevron belt requires roller diameters in excess of 200 mm.

Figure 5 shows an alternative embodiment of the invention in which two additional rows of cleats 10 have been moulded onto the belt 2 along each edge. The extra rows provide additional protection to troughing against loss of produce over the sides of the belt. The belt may be used with a small diameter drive roller.

Figure 6 shows an alternative embodiment of the invention in which two rows of cleats 10 have been moulded along each edge, and the remaining cleats 10 are rhomboidially grouped. Although the above examples use linear arrays of cleats in a group, it will be understood that the invention is not limited to such arrangements. Any grouping of cleats will be effective which allows troughing of the belt and driving of the belt with a small diameter roller while retaining produce during its transport. For example groups of cleats arranged in an arc of a circle would be effective.

Also, although it is preferred to have each group extend only between one edge and the middle of the belt, because this arrangement facilitates constant delivery of produce to the exit point, it is possible to have the cleats grouped so as to form a chain which extends from one edge of the belt to the other without departing from the scope of the invention.

Claims (17)

1 A conveyor belt, the belt having moulded onto its operational outside surface flexible cleats which are arranged to permit retention of conveyed materials, each cleat extending outwardly from the belt to define a cleat axis and having dimensions measured in a plane parallel with that of the belt, and including the cleat axis, all of which are substantially equal, the cleats being spaced far enough apart to permit the direction of orientation of one cleat axis relative to another to change if the belt is made to flex.

2 A belt according to claim 1 wherein the cleats are made of rubber.

3 A belt according to claim 1 wherein the cleats are made of natural rubber.

4 A belt according to any of the preceding claims, wherein the cleats have a Shore hardness value in the range 35 - 70'.

5 A belt according to any of claims 1 - 3, wherein the cleats have a Shore hardness value in the range 45' - 50'.

6 A belt according to any of the preceding claims, wherein the cleats are substantially circular in cross section parallel to the local plane of the belt.

7 A belt according to any of the preceding claims, wherein the cleats are in the range 20 - 75 mm in height.

8 A belt according to any of claims 1 - 6, wherein the cleats are in the range 25 - 50 mm in height.

9 A belt according to any of the preceding claims, wherein the distance between adjacent cleats in a group is in the range 10 -20 mm.

10 A belt according to any of claims 1 - 8, wherein the distance between adjacent cleats in a group is in the range 15 - 25 mm.

11 A belt according to any of the preceding claims, wherein the cleats are arranged in groups, each of which comprises a linear array of cleats which extends substantially perpendicularly from one edge of the belt between a point adjacent to that edge and a point in the the centre of the circumference of the belt, and adjacent groups alternately extending between alternate edges and the centre of the circumference of the belt.

12 A belt according to any of claims 1 -10, wherein the cleats are rhomboidally grouped.

13 A belt substantially as herein described with reference to the accompanying drawings.

14 A conveyor belt installation comprising a conveyor belt according to any of the preceding claims, and a drive roller.

15 A conveyor belt installation according to claim 14, wherein the ratio of drive roller diameter to cleat width is less than 10:1.

16 A conveyor belt installation according to claim 14, wherein the ratio of drive roller diameter to cleat width is in the range 3:1 to 7:1.

17 A conveyor belt installation substantially as herein described with reference to the accompanying drawings.