GB2373777A

GB2373777A - Mobius conveyor belt

Info

Publication number: GB2373777A
Application number: GB0107713A
Authority: GB
Inventors: Robert Steven Drohan
Original assignee: Ace Conveyor Equipment Ltd
Current assignee: Ace Conveyor Equipment Ltd
Priority date: 2001-03-28
Filing date: 2001-03-28
Publication date: 2002-10-02
Also published as: GB0107713D0

Abstract

The invention provides a conveyor belt 10 in the form of a mobius strip. The conveyor belt comprises a single continuous surface 18 provided by at least one twist in the belt. The belt may comprise a strip of sheet material having a first end 14 and a second end 16 at opposite ends thereof and the strip is twisted and joined at the first and second ends to provide the continuous surface of the belt. In a conveyor system, the twist length to width ratio of the belt may be at least 5:1, where the twist extends substantially over half the length of the loop of the joined belt. The twist length to width ratio of the belt may be in the range 20:1 to 8:1, and preferably in the region of 10:1 The mobius strip geometry of the belt enables the conveying surface of the belt to be reverse on each successive cycle thus reducing the amount of wear due to the items being conveyed by at least half.

Description

CONVEYOR BELT

This invention relates to conveyor belts and in particular concerns conveyor belts of the type comprising a flexible endless strip arranged in a loop for transporting articles or granular like materials.

In many fields of activity, particularly those involving high temperature material handling, minerals processing or mining, conveyor belt systems operate in very aggressive environments which can significantly reduce the life expectancy of the belt.

In high temperature processing and material handling environments, for example, belt degradation can occur due to the heat transferred to the belt from the items being conveyed. The surface of the conveyor carrying the conveyed items is often degraded by local heating of the belt surface. This heating can significantly reduce the useful life of the belt, particularly for applications where the belt comprises vulcanised rubber or other low temperature insulating material. For many applications the belt, and in particular the surface of the belt in contact with the conveyed items, will cool sufficiently on the return run of the conveyor when the belt surface for conveying is not in contact with the high temperature conveyed items. In particularly high temperature environments, cooling of the belt and/or the conveyed items may be necessary in order to increase belt life to an acceptable number of cycles.

In other applications such as materials procc ing or mining, belt degradation can occur as a result of abrasion caused by the action of irregularly shaped items of varying size continually being loaded and unloaded on the conveying surface of the belt.

Wear due to abrasion is also relevant to many other conveyor belt applications regardless of the operating environment. For example, significant wear can occur on the under surface of the belt in contact with the end rollers or drums, and/or guide rollers or drums positioned on the inside of the belt between the conveying and return runs of the conveyor system. Belt wear can cause conveyor malfunction and down time due to belt misalignment, slipping and possibly belt failure.

There is a general requirement to increase the life expectancy of a conveyor belt. In particular there is a requirement to increase the life of a conveyor belt in high temperature operating environments and/or other aggressive operating environments.

There is also a requirement to improve the wear characteristics of conveyor belts constructed using conventional belt materials, for instance vulcanised rubber.

According to an aspect of the invention there is provided a mobius strip conveyor belt. A conveyor belt which is in the form of a mobius strip has many advantages over conventional conveyor belts in that the continuous surface provided by the mobius strip geometry enables both sides of the belt to be used to transport items on the conveyor belt. This can significantly reduce wear of the belt and effectively double the life expectancy of the belt when compared with conveyor belts without a mobius

strip type twist. The mobius strip geometry enables the side of the conveyor belt that is in contact with the items being conveyed to be reversed on each successive cycle.

By using both sides of the belt it is possible to reduce the amount of wear, due to the items being conveyed, by at least a half and also to distribute the wear, due to more evenly over the continuous surface provided by the mobius strip. In this respect any wear marks due to engagement with end rollers or drums or any guide rollers positioned between the conveying side and return run of the conveyor belt will be evenly distributed on both sides of the belt. The mobius strip geometry is particularly important for use in high temperature applications since the proportion of the belt cycle available for surface cooling is increased by a factor of 2 since the time during which the conveyed material is in contact with the belt is reduced to 25% of the total cycle time. This compares with 50% for the standard untwisted conveyor belt. For conveyor belts carrying hot materials, the change to 75% cooling time from 50% more than doubles the belt life as the mean belt temperature is lowered and exposure to heat halved in terms of direct contact with hot items being conveyed. This reduction in wear and improvement in cooling time can significantly improve the operating efficiency of a conveyor system comprising a mobius strip conveyor belt since maintenance and down time can be significantly reduced. It is envisaged that conveyor systems comprising a mobius strip conveyor belt will have significantly reduced operating costs and improve operational efficiency.

According to another aspect of the invention there is provided a conveyor belt comprising a single continuous surface provided by at least one twist in the said belt.

This aspect of the invention contemplates conveyor belts in which a single continuous surface is provided by one or an odd number multiple of twists in the belt. This may be important for certain applications where a continuous surface is required as with a mobius strip conveyor belt but where it is desirable to provide say three twists in the belt at different points along its length.

Preferably, the said at least one twist comprises a single 180 degree twist. This provides a conveyor belt in which the continuous surface is provided with a single 180 degree twist in the same way as the mobius strip conveyor belt mentioned above.

In preferred embodiments, the said belt comprises a strip of sheet material having a first end and a second end at opposite ends thereof and the said strip is twisted and joined at the said first and second ends to provide the said continuous surface. This readily enables a mobius strip conveyor belt to be formed from a single strip of sheet material.

Preferably, the twist length to width ratio of the said belt is at least 5: 1, where the said twist extends substantially over half the length of the loop of the joined belt. In order to prevent overstressing of the side edges of the conveyor belt along the twist it is necessary to limit the twist length to width ratio of the belt. The present inventor has found that a twist length to width ratio of at least 5: 1 can prevent excessive tensile stresses being developed along the edges of the twisted part of the conveyor belt when installed in a conveyor system. By maintaining the tensile stresses along the edges within acceptable limits the belt can be tensioned in the usual way without the edges

distorting due to excessive stress. This is significant as it readily enables a mobius strip type conveyor belt to be used in applications where a wide but short belt is required.

In preferred embodiments, the twist length to width ratio of the said belt is in the range 20: 1 to 8: 1. The inventor has found that the above properties are significantly improved when the twist length to width ratio of the conveyor belt is in the range 20: 1 to 8: 1.

In a preferred embodiment, the twist length to width ratio of the said belt is in the region of 10 : 1. The inventor has found in particular that when the twist length to width ratio of the conveyor belt is 10 : 1, or in the region thereof, the tensile stresses developed along the edges of the twisted part of the conveyor belt are easily accommodated by the belt without distorting the belt to any significant extent.

Preferably, the said belt has a first side and a second side on opposite sides thereof, and the said belt comprises a central core reinforcement section positioned between the said first and second sides. The central core reinforcement readily enables relatively heavy loads to be supported by the belt when in use.

In preferred embodiments, the said core section is positioned substantially midway between the said first and second sides of the said belt. This provides a symmetrical belt cross-section in the plane orthogonal to the longitudinal direction of the belt so that the belt is balanced during operation and provides equal strength and stiffness

characteristics on both sides thereof.

According to a further aspect of the invention there is provided a conveyor system comprising a mobius strip conveyor belt.

According to a further aspect of the invention there is a conveyor system comprising a conveyor belt having a continuous surface provided by least one twist in the said belt.

Preferably, the said belt provides a conveying run for conveying material or articles in a direction of movement of the said belt from an upstream end of the said conveyor system to a downstream end thereof, and a return run, and wherein the said conveying and return runs are spaced apart so that the said twist does not cause interference between the said runs. Interference between the twist and one of the conveying or return runs can be prevented by separating the respective runs by at least half the width distance of the belt, but preferably more than this so that the edge of the twist at a mid-point in the twist does not contact the inner facing surface of the opposing run of the belt in the conveyor system.

In preferred embodiments, the said at least one twist is in the said return part. In this way the conveying side or run can provide a substantially flat continuous surface for the items being conveyed from an upstream end to a downstream end of the conveyor belt.

Preferably, the said at least one twist extends substantially over the length of the said return part. This enables the width to length ratio of the conveyor belt to be maximised and thereby the tensile stresses in the edges of the twist to be minimised within the belt.

In preferred embodiments, the said return part has a central longitudinal axis which is spaced from the said conveying part by a distance greater than half the width of the said belt. In this way it is possible to avoid interference of one of the edges of the twist with a internal facing surface of the conveying side or run.

Preferably, the conveyor system further comprises a scraping means for cleaning the said continuous surface of the said belt. This can be important in embodiments where the conveyor belt is used to convey products which tend to form accumulations of small particles of moist dust coagulating on the surface of the conveyor belt which, in the absence of a scraper device, would tend to accumulate on the belt itself. In such an embodiment it is necessary to clean the continuous surface before it contacts a next one of the end rollers.

In preferred embodiments the conveyor system further comprises a conveyor belt roller positioned at the said upstream end of the system, and wherein the said scraping means is positioned to scrap the said continuous surface before the said surface contacts the said roller. In this way the scraping means can be positioned on the return run and preferably in the region of the twist at a position on the twist where the twist is disposed in a plane substantially orthogonal to that of the conveying side of

the belt. In this respect material deposited on the continuous surface may be released by the scraper so that it falls in a direction away from the conveying run of the belt, preferably by gravity.

Various embodiments of the invention will now be more particularly described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic perspective view of a mobius strip conveyor belt; and, Figure 2 is a schematic perspective view of a mobius strip conveyor belt installed in a conveyor system.

Referring to Figure 1, a conveyor belt 10 in the form of a mobius strip is formed from a flexible sheet material 12 such as vulcanised rubber or polypropylene around a reinforced fabric, cord or steel core (not shown). The mobius strip is formed from a single strip of material 12 which is twisted and joined at respective first and second ends 14,16 to provide a continuous surface 18 on the strip.

In Figure 2, the mobius strip conveyor belt 10 is installed in a conveyor system 20 which comprises a pair of end rollers 21 and 22 positioned at respective upstream and downstream ends of the conveyor system as indicated by the forward direction of movement of the conveyor by arrow 23. The conveyor belt 10 is shown transporting single item products 24 on a conveying side or run of the conveyor system from the upstream and to the downstream and thereof. The twist indicated at 25 is provided on the opposite side of the conveyor belt 10 to that of the conveying run 24. The conveyor belt is moderately tensioned between the rollers 21 and 22 such that the

twist 25 extends substantially along the entire length of the return run between the rollers 21 and 22. In this respect the twist length is approximately half that of the overall loop length of the conveyor belt. The width of the conveyor belt 10 as indicated at 26 is determined by the length of the twist 25 between the rollers 21 and 22 and a preferred twist length to width ratio. In order to prevent significant tensile stresses developing along the edges 27 of the belt in the twist section 25 the conveyor belt 10 has a twist length to width ratio of at least 5: 1; and, preferably this ratio is in the range 20: 1 to 8: 1; and, more preferably it is in the region of about 10: 1.

The rollers 21 and 22 separate the conveying and return runs of the conveyor belt system so that the twist 25 does not interfere with the internal surface indicated 28 on the opposite side of the conveying run facing the twist 25. In this respect the diameters of the rollers 21 and 22 is preferably at least 60% of the belt width 26.

In preferred embodiments a belt scraper 29 of a generally conventional contstruction is provided to scrape the continuous surface 18 of the conveyor belt so that deposits of material that have accumulated on the continuous surface in the conveying run are removed prior to the continuous surface contacting the roller 21 at the upstream end of the conveyor belt system.

Although aspects of the invention have been described with reference to the embodiments shown in the accompanying drawings it is to be understood that the invention is not limited to those precise embodiments and various changes and modifications may be affected without exercise of further inventive skill and effort.

Claims

CLAIMS 1. A mobius strip conveyor belt.
2. A conveyor belt comprising a single continuous surface provided by at least one twist in the said belt.
3. A conveyor belt as claimed in Claim 2 wherein the said at least one twist comprises a single 180 degree twist.
4. A conveyor belt as claimed in Claim 3 wherein the said belt comprises a strip of sheet material having a first end and a second end at opposite ends thereof and the said strip is twisted and joined at the said first and second ends to provide the said continuous surface.
5. A conveyor belt as claimed in any one of Claims 2 to 4 wherein the twist length to width ratio of the said belt is at least 5 : 1, where the said twist extends substantially over half the length of the loop of the joined belt.
6. A conveyor belt as claimed in Claim 5 wherein the twist length to width ratio of the said belt is in the range 20: 1 to 8: 1.
7. A conveyor belt as claimed in Claim 6 wherein the twist length to width ratio

of the said belt is in the region of 10 : 1
8. A conveyor belt as claimed in any one of Claims 2 to 7 wherein the said belt has a first side and a second side on opposite sides, and the said belt comprises a central core reinforcement section positioned between the said first and second sides.
9. A conveyor belt as claimed in Claim 8 wherein the said core section is positioned substantially midway between the said first and second sides of the said belt.
10. A conveyor system comprising a mobius strip conveyor belt.
11. A conveyor system comprising a conveyor belt having a continuous surface provided by least one twist in the said belt.
12. A conveyor system as claimed in Claim 11 wherein the said at least one twist comprises a single 180 degree twist.
13. A conveyor belt as claimed in Claim 11 or Claim 12 wherein the twist length to width ratio of the said belt is at least 5: 1.
14. A conveyor belt as claimed in Claim 13 wherein the twist length to width ratio of the said belt is in the range 20: 1 to 8: 1.
15. A conveyor belt as claimed in Claim 14 wherein the twist length to width ratio of the said belt is in the region of 10 : 1
16. A conveyor system as claimed in any one of Claims 11 to 15 wherein the said belt provides a conveying run for conveying material or articles in a direction of movement of the said belt from an upstream end of the said conveyor system to a downstream end thereof, and a return run, and wherein the said conveying and return runs are spaced apart so that the said twist does not cause interference between the said runs.
17. A conveyor system as claimed in Claim 16 wherein the said at least one twist is in the said return part.
18. A conveyor system as claimed in Claim 17 wherein the said at least one twist extends substantially over the length of the said return part.
19. A conveyor system as claimed in any one of Claims 16 to 18 wherein the said return part has a central longitudinal axis which is spaced from the said conveying part by a distance greater than half the width of the said belt.
20. A conveyor system as claimed in any one of Claims 11 to 19 further comprising a scraping means for scraping the said continuous surface of the said belt.
21. A conveyor system as claimed in Claim 20 further comprising a conveyor belt roller positioned at the said upstream end of the system, and wherein the said scraping means is positioned to scrap the said continuous surface before the said surface contacts the said roller.