AU2016100198A4 - Roller - Google Patents

Abstract

The present invention provides a roller (11) comprising a shaft (13) and an end cap assembly rotatably secured adjacent each end of the shaft. The roller also comprises a roller casing (31) extending between the end cap assemblies wherein the roller casing is a composite material comprising at least an inner layer (35) and an outer layer (37) wherein the outer layer has wear resistant properties. 4It 1733 FIGURE 7 FlGUR E 8

Description

ROLLER TECHNICAL FIELD [0001] The present invention relates to a roller for use in conveyors. In particularly the inventions relates to roller construction. BACKGROUND ART [0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application. [0003] Conveyors are used in many industries to convey material from one location to another for various purposes. By way of example, in the mining industry conveyors are used to carry ore or other material around a site, from site to site, as well as to loading bays and on to ships, trains, trucks and/or other suitable transportation. [0004] Most conveyors employ a conveyor belt that moves over a series of supporting, rotatable rollers (or idlers). The conveyor belt moves over the rollers, with the underside of the conveyor belt contacting the rollers, while the upper side of the conveyor belt carries the material being conveyed. [0005] The rollers are generally supported beneath the conveyor belt in roller frames which are typically mounted beneath the conveyor belt, with each roller frame typically supporting multiple rollers. These rollers support the load of the material conveyed on the conveyor belt and are often under constant heavy load. For example, the belts in the iron ore mining industries carry very large loads, up to 10,000 tonnes per hour, 24 hours per day. [0006] Rollers are generally constructed to have a roller casing mounted onto a shaft. The roller casing is rotatably secured to the shaft by two end caps located adjacent each end of the shaft. These end caps support bearings which allow rotation of the roller casing relative to the shaft. To ensure that the end caps do not restrict the rotation of the shaft relative to the roller casing, a recess is provided between the shaft and the end caps. To prevent contaminant particles from entering the recess and damaging the bearings washers encircle the openings of the recesses at the position of the protruding ends. [0007] The design of rollers has not changed significantly over recent decades. Traditionally rollers are made from steel and are designed to operate in harsh, abrasive conditions where the loads and wear experienced by the rollers is significant. To withstand these conditions rollers need to be very robust, which typically means the steel used to construct the roller is of heavy gauge, leading to a very heavy roller. For instance, the weight of rollers used on mine sites ranges between 25kg and 33kg. This is problematic when maintenance technicians need to repair or replace a roller. [0008] This problem is further exasperated by the lack of space between adjacent roller frames making it difficult for a maintenance technician to access rollers. Due to the proximity of adjacent roller frames to each other, when a roller needs to be replaced the technician will typically be required to manually remove it from the roller frame, and similarly, manually reposition a replacement roller in the roller frame. [0009] Another downside of current rollers is that they are generally designed to be an integrated unit, making the replacement of any components that fail very difficult/impossible without damaging other components. As a result rollers are typically disposed of once they have failed. Thus, once a component of the roller is damaged or worn out, inevitably the whole roller must be replaced. [0010] For instance, replacement of the bearings, when damaged or worn, is not practical in current rollers as the end caps are fixedly attached to the outer casing. As this fixed attachment provides the roller with its integrity and strength , any attempt to replace bearings in rollers would result in the destruction of the integrity of the roller compromising the strength of the roller.. SUMMARY OF INVENTION [0011] The present invention attempts to reduce the prior art problems by providing a roller that is of light weight construction. It is therefore an object of the invention to provide a roller which is of light weight construction.

[0012] The present invention provides a roller comprising: a shaft; an end cap assembly rotatably secured adjacent each end of the shaft a roller casing extending between the end cap assemblies, wherein the roller casing is a composite material comprising at least an inner layer, and an outer layer wherein the outer layer has wear resistant properties. [0013] In contrast to the prior art the composite construction of the roller casing can use different materials which, once combined, provide the requisite wear and strength characteristics, while being significantly lighter than if the roller casing was made from steel. [0014] The shaft may be of hollow construction. The shaft may be made from carbon fibre and/or carbon steel. This further reduces the weight of the roller while still providing the requisite strength. The replacement of a solid steel shaft, as is the case with prior art rollers, with a hollow shaft saves approximately 4kg in weight of a standard roller used on mine sites. [0015] Each end of the shaft may receive end plugs. Each end plug may be configured to engage with a roller frame of the conveyor system to support the roller therein. Each end plug may receive a bearing thereon. With this arrangement the end plugs carry the load applied to the roller, and transfer it to the roller frames. [0016] In one aspect of the invention each end plug is made from carbon steel. [0017] In another aspect of the invention each end plug is made from carbon fibre. [0018] Each end cap assembly may comprise an end cap, at least one bearing, and at least one seal. [0019] In one aspect of the invention each end cap is formed from carbon fibre. [0020] In another aspect of the invention each end cap is formed from a lightweight alloy.

[0021] Each end cap may incorporate a plurality of blind holes therein to further reduce the weight of the end caps. Other measures, as known to the person skilled in the art, may also be employed to reduce the weight of the roller. [0022] Preferably the roller casing is mechanically fixed to each end cap assembly. Preferably one end cap assembly is fixed to one end of the roller casing, while the other end cap assembly is fixed to the other end of the roller casing. [0023] The roller casing may be releasably secured to each end cap. [0024] In one aspect of the invention the roller casing is mechanically fixed to each end cap assembly by at least one pin pinning the roller casing to each end cap. The at least one pin may be in the form of a carbon fibre dowel. The at least one pin may be removable. The at least one pin may extend through the inner layer into an aperture in the side of the end cap. The at least one pin may be covered by the outer layer to prevent the at least one pin from being removed from the end cap. The at least one pin may be glued in position. There may be four pins at each end of the roller casing, placed equidistant apart to ensure the roller is balanced. [0025] In another aspect of the invention the mechanical fixing is by way of crimping the roller casing to each end cap. Preferably each end cap has a groove or a plurality of dimples machined therein in a symmetrical manner. During assembly an end portion of the roller casing may be crimped such that the roller casing protrudes into each groove or dimple to fix the roller casing to the respective end cap assembly. [0026] Alternatively each end cap may comprise a plurality of indentations such that upon crimping of the roller casing, the roller casing is caused to be received in the indentations to fix the roller casing to the end cap assembly. [0027] Each end cap may have a tapering edge along its outer periphery such that upon crimping of the roller casing an outer edge of the roller casing assumes the profile of the tapered edge. [0028] Preferably the roller may be disassembled. [0029] Preferably the shaft, bearings and/or the at least one seal may be removable from the roller. This will allow the at least one bearing, or other worn or damaged components to be replaced and the roller re-assembled for continued use.

[0030] The inner layer of the roller casing may comprise a plurality of layers. [0031] The outer layer may comprise a plurality of layers. [0032] All layers may have an epoxy or other form of adhesive therebetween. [0033] One or more layers may be of different colour to provide a visual wear indicator, allowing an operator to visually identify the degree of wear of the roller. [0034] One of the layers may be a carbon ceramic layer. The carbon ceramic layer may be an outer layer. [0035] In one aspect of the invention the roller casing is a carbon fibre composite construction. The casing's inner layer may be carbon fibre, and the outer layer may be made from an abrasive resilient material. The thickness of the inner layer may be in the order of 4mm. The thickness of the outer layer may be in the order of 3mm. [0036] The inner layer may be formed by combining carbon fibre and resin at high temperature to form a carbon fibre tube. The tube may be manufactured such that it comprises multiple layers. The layers may be formed from different coloured carbon fibre so as to provide a visual indicator of the degree of roller wear. [0037] The outer layer may be formed by applying an abrasion resistant layer to the inner layer. The outer layer may be a high molecular weight polyethylene sleeve, a chopped strand mat (CSM) laminate, or may be formed from polyurethane. The outer layer may be sprayed on or brushed on. [0038] In another aspect of the invention the roller casing is an aluminium, steel composite construction. The casing's inner layer may be made from aluminium, and the outer layer made from carbon steel. The carbon steel may be sprayed on to the inner layer. The inner layer may be in the order of 7mm thick. The outer layer may be in the order of 20 microns thick. [0039] The roller may have a cavity defined between the end cap assemblies, the shaft and the roller casing. The cavity may be filled with a material which does not expand or contract when exposed to changes in temperature. Preferably the material does not absorb heat.

[0040] Preferably the material is polyurethane. The material may be injected into the cavity such that there is substantially no air in the roller cavity. As there is no air in the cavity there will be no build up of temperature. Also, as the cavity is full of the injected material no dirt can pass into the cavity and into the bearings. The material also reduces the noise generated by the roller. [0041] Preferably, once the material has been injected into the roller casing, the roller casing and end cap assemblies are rotatable about the shaft whereby the shaft does not damage the injected material. [0042] In another aspect of the invention the roller casing is of a polyurethane composite construction. The casing's inner layer may be made from polyurethane having light weight characteristics, and the outer layer may be made from polyurethane having wear resistant characteristics. The inner layer may extend from the outer layer to a shaft cavity which receives the shaft. The inner layer may have higher wear characteristics nearer the outer layer. Each end cap may be integral with the roller casing. The end cap may be integrally formed with the outer layer and inner layer. With an end cap as part of the whole roller, the roller is stronger and less expensive to manufacture when compared to current rollers. [0043] In contrast to the prior art, the construction of the roller of the present invention is significantly lighter and quieter while still meeting the required load and \Near conditions. [0044] The present invention provides a roller for use on a conveyor, the roller having a roller casing formed from a composite material comprising at least an inner layer, and an outer layer wherein the outer layer has wear resistant properties. [0045] The present invention provides a roller for use on a conveyor, the roller having a roller casing formed from a composite material comprising at least an inner layer, and an outer layer wherein the outer layer has wear resistant properties, wherein one of the layer incorporates a visual indicator so that an operator may visually identify the degree of wear experienced by the roller. [0046] The inner layer may extend from the outer layer inwardly to define a cavity in which a roller shaft may be received.

[0047] The present invention provides a conveyor having one or more of the rollers as herein before described fitted thereto. [0048] The present invention provides a roller comprising: a shaft an end cap assembly rotatably secured adjacent each end of the shaft; a roller casing extending between the end cap assemblies, wherein end caps of the end cap assembly are removably secured to the roller casing. [0049] Preferably the roller casing is made from polyurethane. [0050] Each end cap assembly comprises an end cap which may be integrally formed with the roller casing. In this arrangement each end cap and roller casing are formed as a unitary member. [0051] The present invention further provides a roller comprising: a shaft; a first end cap assembly and a second end cap assembly each being rotatably secured adjacent opposing ends of the shaft; a roller casing extending from the first end cap assembly to the second end cap assembly, wherein an end cap of each end cap assembly is removably secured to each end of the roller casing. [0052] The present invention further provides a roller comprising: a shaft; a first end cap assembly and a second end cap assembly each being rotatably secured adjacent opposing ends of the shaft, each end cap assembly comprising an end cap, a seal and a bearing; a composite roller casing extending from the first end cap assembly to the second end cap assembly, wherein the roller casing is crimped to each end cap such that each end cap assembly is removably secured to each end of the roller casing. [0053] The present invention further provides a roller comprising: a shaft; an end cap assembly rotatably secured adjacent each end of the shaft; a roller casing extending between the end cap assemblies, wherein the roller casing is a composite material comprising at least a non-metallic inner layer and an outer layer wherein the outer layer has wear resistant properties. [0054] The present invention further provides a roller comprising: a shaft an end cap assembly rotatably secured adjacent each end of the shaft; a roller casing extending between the end cap assemblies, wherein end caps of the end cap assembly are removably secured to the roller casing, the roller casing being a composite material comprising at least an inner layer and an outer layer wherein the outer layer has wear resistant properties, whereby the casing's inner layer is aluminium, and the outer layer is carbon steel, wherein the carbon steel is sprayed on to the inner layer. [0055] The present invention further provides a roller comprising: a shaft; a first end cap assembly and a second end cap assembly each being rotatably secured adjacent opposing ends of the shaft, each end cap assembly comprising an end cap, a seal and a bearing; a composite roller casing extending from the first end cap assembly to the second end cap assembly, wherein the roller casing is mechanically fixed to each end cap assembly by at least one pin pinning the roller casing to each end cap such that each end cap assembly is removably secured to each end of the roller casing.

[0056] The present invention further provides a roller comprising: a shaft; a first end cap assembly and a second end cap assembly each being rotatably secured adjacent opposing ends of the shaft, each end cap assembly comprising an end cap formed from carbon fibre, a seal and a bearing; a composite roller casing extending from the first end cap assembly to the second end cap assembly, wherein the roller casing is crimped to each end cap such that each end cap assembly is removably secured to each end of the roller casing. [0057] The present invention further provides a roller comprising: a shaft; a first end cap assembly and a second end cap assembly each being rotatably secured adjacent opposing ends of the shaft, each end cap assembly comprising an end cap, a seal and a bearing; a composite roller casing extending from the first end cap assembly to the second end cap assembly, wherein the roller casing is crimped to each end cap such that each end cap assembly is removably secured to each end of the roller casing, wherien each end cap has a tapering edge along its outer periphery such that upon crimping of the roller casing an outer edge of the roller casing assumes the profile of the tapered edge. [0058] The present invention further provides a roller comprising: a shaft; an end cap assembly rotatably secured adjacent each end of the shaft; a roller casing extending between the end cap assemblies, wherein the roller casing is a composite material comprising at least a non-metallic inner layer and an outer layer wherein the outer layer has wear resistant properties; the non-metallic inner layer comprising carbon fibre wherein the carbon fibre is uni-directional. [0059] The present invention further provides a roller for use on a conveyor, the roller having a composite roller casing rotatably secured to a shaft, the roller casing formed from non-metallic materials, the roller casing comprising at least an inner layer, and an outer layer wherein the outer layer has wear resistant properties, wherein one or more layers are of different colour to the other layers to provide a visual wear indicator so that an operator is able to visually identify the degree of wear experienced by the roller. [0060] The present invention further provides a roller comprising: a shaft; an end cap assembly rotatably secured adjacent each end of the shaft; a roller casing extending between the end cap assemblies, wherein end caps of the end cap assembly are removably secured to the roller casing, the roller casing being a composite material comprising at least an inner layer and an outer layer wherein the outer layer has wear resistant properties, whereby the casing's inner layer is aluminium, and the outer layer is carbon steel wherein the carbon steel is sprayed on to the inner layer in the order of 20 microns thick. BRIEF DESCRIPTION OF THE DRAWINGS [0061] Further features of the present invention are more fully described in the following description of non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which: Figure 1 is a cross sectional view of a roller according to a first embodiment of the invention without a shaft and bearings depicted; I t Figure 2 is a cross sectional view of the roller in figure 1 without an outer layer depicted; Figure 3 is a front perspective view of an end cap of the roller shown in figure 1; Figure 4 is a cross sectional side view of the end cap shown in figure 3; Figure 5 is a side view of a shaft for use with the roller shown in figure 1; Figure 6 is a cross sectional view of the shaft in figure 5 taken along AA; Figure 7 is a perspective view of a roller according to a second embodiment of the invention showing an alternative method of securing the end caps and roller casing of a roller; and Figure 8 is a cross sectional view of one end of the roller of figure 7. [0062] In the drawings like structures are referred to by like numerals throughout the several views. The drawings shown are not necessarily to scale, with emphasis instead generally being placed upon illustrating the principles of the present invention. DESCRIPTION OF EMBODIMENTS [0063] The invention according to a first embodiment is in the form of a roller 11. These rollers are used in conveyors where a plurality of rollers 11 are supported in roller frames mounted beneath a conveyor belt. These rollers support and transfer the load of the material conveyed on the conveyor belt. [0064] Referring to figures 1 to 6, the roller 11 comprises a shaft 13. The shaft 13 comprises a hollow pipe 14 and an end plug 15 inserted into each end of the hollow pipe 14. Each end plug 15 is adapted to be received in a roller cradle of the roller frame (not shown). [0065] Each end of the roller 11 also comprises an end cap assembly which is rotatably secured adjacent each end plug 15 of the shaft 13. [0066] Each end cap assembly comprise an end cap 21, a bearing (not shown), and a series of seals (not shown). [0067] To reduce weight each end cap 21 comprises a series of blind holes 23. As shown in figure 4, each end cap 21 provides a shoulder 25 which extends radially outward adjacent an outer face 27 of the end cap 21. Each end cap 21 also has two apertures 29 extending radially inward for reasons which will be described below. [0068] The two end cap assemblies are fixed relative to each other by a roller casing 31 such that they rotate simultaneously. The roller casing 31 extends between the end cap assemblies and is held in position relative to the end caps 21. [0069] The roller casing 31 comprises an inner layer 35 and an outer layer 37 such that the roller casing 31 is a composite construction. [0070] In the present embodiment the inner layer 35 is formed from high strength carbon fibre. By roll wrapping, or filament winding, the carbon fibre is mixed with resin to form a tube 39 of carbon fibre having unidirectional piles. The thickness of the tube 39 is in the order of approximately 4mm. [0071] Once the tube 39 is formed to the required length the end caps 21 may be positioned in either end. The end caps 21 are inserted into respective ends of the tube 39 until the edge of the tube 39 abuts the shoulder 25 of each end cap 21. Pins in the form of dowels 41 are then inserted through the tube 39 and glued into the apertures 29 of the end caps. This will secure the end caps 21 to the roller casing 31. [0072] The outer layer 37 may then be formed over the inner layer 35. When forming the outer layer, the outer layer encapsulates the inner layer 35 and extends over the shoulder 25 to terminate substantially adjacent the outer face 27 of each end cap 21, concealing the dowels 41, as best shown in figure 1. [0073] The outer layer 37 is formed by spraying polyurethane directly onto the inner layer 35 to a thickness of 3mm. The polyurethane may also be cast thereon, or otherwise formed as would be known to the person skilled in the art. [0074] In an alternative construction the outer layer may be in the form of a polyethylene sleeve.

[0075] In a further alternative construction the outer layer may be in the form of a SiC/ CSM laminate. A sleeve is manufactured from the CSM/SiC filled resin. During the manufacture of the sleeve it is important that there are minimal voids, that any butt joints do not coincide and that there are no gaps between the edges of the material. The sleeve is allowed to cure before placing the completed sleeve on a machine capable of grinding the external surface parallel to the centreline of the tube. Minimal material shall be removed, so that the remaining wall thickness shall be a minimum of 3mm over the entire sleeve. A final layer of resin is applied before it is placed over the inner layer 35. [0076] The roller 11 also incorporates a cavity 33 which is defined between the end cap assemblies, the shaft 13 and the roller casing 31. In the present embodiment the cavity 33 is injected with a temperature compensating means (not shown), in the form of polyurethane. The polyurethane is injected into the cavity 33 such that the air is expelled from the cavity 33 and there are no pockets of air left therein. [0077] Once the polyurethane is injected and set the shaft 13 is placed in the roller and the bearings fitted thereto to complete the assembly of the roller. Alternatively the shaft may be formed such that it can remain in place while the polyurethane is injected. [0078] Figures 7 and 8 illustrate a second embodiment of a roller 111 according to the present invention. For convenience features that are similar or correspond to features of the roller 11 of the first embodiment have been referenced with the same reference numerals. The significant difference between the first embodiment and the second embodiment is the manner in which the roller casing is secured to the end caps. [0079] In this embodiment an alternative method of fixing a roller casing 131 of the roller 111 to end caps 121 is used whereby the roller casing 131 is crimped to the end caps 121. In such a method each end cap 121 has three indentations 133 incorporated in an annular tapering edge 135 of each end cap 121. During construction, the roller casing 131 is crimped to take the shape of the tapering edge 135. In so doing a portion of the roller casing 131 is received in each indentation 133 to hold the roller casing and end caps in an assembled condition. [0080] To further enhance the roller of the present invention the end cap may be made from a light weight alloy capable of withstanding significant loading. This can be achieved by forging the material at 20000C. This process makes the end cap very light I-T weight and at least four times stronger than carbon steel. With such an end cap the roller may be easily refurbished when the roller bearings/seals are damaged, without affecting the fine tolerance or the balance of the roller. [0081] The configuration of the roller provides a lightweight alternative to present day rollers without compromising strength or wear characteristics. This itself has cost benefits to the conveyor operator but also allows the maintenance technicians to complete any roller maintenance/replacement in a safer manner. [0082] As may be noted by the construction of the roller 11, any damaged or worn seal, bearing or end cap may be replaced or repaired. It is therefore not necessary to dispose of the whole roller when a component fails. [0083] While the above discussion considers conveyors in the mining environment the present invention has application to any roller used in any conveying or similar system. [0084] Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention. [0085] Reference to positional descriptions, such as lower and upper, are to be taken in context of the embodiments depicted in the figures, and are not to be taken as limiting the invention to the literal interpretation of the term but rather as would be understood by the skilled addressee. [0086] Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims (34)

1. A roller comprising: a shaft; a first end cap assembly and a second end cap assembly each being rotatably secured adjacent opposing ends of the shaft, each end cap assembly comprising an end cap, a seal and a bearing; a composite roller casing extending from the first end cap assembly to the second end cap assembly, wherein the roller casing is crimped to each end cap such that each end cap assembly is removably secured to each end of the roller casing, wherien each end cap has a tapering edge along its outer periphery such that upon crimping of the roller casing an outer edge of the roller casing assumes the profile of the tapered edge.

2. A roller comprising: a shaft; an end cap assembly rotatably secured adjacent each end of the shaft; a roller casing extending between the end cap assemblies, wherein the roller casing is a composite material comprising at least a non-metallic inner layer and an outer layer wherein the outer layer has wear resistant properties; the non-metallic inner layer comprising carbon fibre wherein the carbon fibre is uni-directional.

3. The roller according to claim 1 or 2 wherein the shaft is of hollow construction, wherein each end of the shaft receives an end plug, each end plug being configured to engage with a roller frame of a conveyor system to support the roller therein, each end plug housing a bearing.

4. The roller according to claim 1, 2 or 3 wherein the shaft is made from carbon fibre and/or carbon steel.

5. The roller according to claim 3 or 4 wherein each end plug is made from carbon steel and/or carbon fibre.

6. The roller according to any one of claims 2 to 5 wherein each end cap assembly comprises an end cap, at least one bearing, and at least one seal.

7. The roller according to claim 6 wherein each end cap is formed from carbon fibre and/or a lightweight alloy, wherien the alloy has been forged at or above 20000C.

8. The roller according to claim 6 or 7 wherein each end cap incorporates a plurality of blind holes therein.

9. The roller according to any one of the preceding claims wherein the roller casing is mechanically fixed to each end cap assembly.

10. The roller according to any one of claims 6 to 9 wherein the roller casing is releasably secured to each end cap.

11. The roller according to any one of the preceding claims wherein the roller casing is mechanically fixed to each end cap assembly by at least one pin pinning the roller casing to each end cap.

12. The roller according to claim 11 wherein the at least one pin is in the form of a carbon fibre dowel which extends through the inner layer of the roller casing into an aperture in the side of the end cap.

13. The roller according to claim 12 wherein the at least one pin is covered by the outer layer of the roller casing to prevent the at least one pin from being removed from the end cap.

14. The roller according to claim 11, 12 or 13 wherein there are four pins at each end of the roller casing, placed equidistant apart.

15. The roller according to any one of claims 2 to 11 wherein the roller casing is mechanically fixed by way of crimping the roller casing to each end cap. I I

16. The roller according to claim 1 or 15 wherein each end cap has a groove or a plurality of dimples machined therein in a symmetrical manner, whereby during assembly an end portion of the roller casing is crimped such that the roller casing protrudes into each groove or dimple to fix the roller casing to the respective end cap assembly.

17.The roller according to claim 15 wherein each end cap comprises a plurality of indentations such that upon crimping the roller casing, the roller casing is caused to be received in the indentations to fix the roller casing to the end cap assembly.

18. The roller according to claim 15, 16 or 17 when dependent on claim 2 wherein each end cap has a tapering edge along its outer periphery such that upon crimping of the roller casing an outer edge of the roller casing assumes the profile of the tapered edge.

19.The roller according to any one of the preceding claims wherein the inner layer of the roller casing comprises a plurality of layers.

20. The roller according to any one of the preceding claims wherein the outer layer comprises a plurality of layers.

21.The roller according to claim 19 or 20 wherein all layers have an adhesive therebetween.

22.The roller according to claim 19, 20 or 21 wherein one or more layers are of different colour to the other layers to provide a visual wear indicator.

23. The roller according to any one of the preceding claims wherein one of the layers is in the form of a carbon ceramic layer.

24. The roller according to any one of claims 1, or 3 to 23 when dependent on claim 1 wherein the roller casing is a carbon fibre composite construction, whereby the casing's inner layer is carbon fibre and the outer layer is made from an abrasive resilient material.

25. The roller according to claim 24 wherein the outer layer is formed by applying an abrasion resistant layer to the inner layer.

26. The roller according to any one of the preceding claims wherein the roller has a cavity defined between the end cap assemblies, the shaft and the roller casing, the cavity being filled with a material, where upon exposure to changes in temperature the material does not expand or contract, nor absorb heat.

27. The roller according to claim 26 wherein once the material has been injected into the roller casing, the roller casing and end cap assemblies are rotatable about the shaft whereby the shaft does not damage the injected material.

28. The roller according to any one of claims 1, and 3 to 22 when dependent on claim 1 wherein the roller casing is of a polyurethane composite construction, whereby the casing's inner layer is made from polyurethane having light weight characteristics, and the outer layer is made from polyurethane having wear resistant characteristics.

29. The roller according to claim 28 wherein the inner layer extends from the outer layer to a shaft cavity which receives the shaft.

30. The roller according to claim 28 or 29 wherein each end cap is integral with the roller casing, the end cap being integrally formed with the outer layer and inner layer such that each end cap and roller casing are a unitary member..

31.A roller for use on a conveyor, the roller having a composite roller casing rotatably secured to a shaft, the roller casing formed from non-metallic materials, the roller casing comprising at least an inner layer, and an outer layer wherein the outer layer has wear resistant properties, wherein one or more layers are of different colour to the other layers to provide a visual wear indicator so that an operator is able to visually identify the degree of wear experienced by the roller.

32.The roller according to claim 31 wherein the inner layer extends from the outer layer radially inward to define a cavity in which a roller shaft is received.

33.A roller comprising: a shaft; an end cap assembly rotatably secured adjacent each end of the shaft; a roller casing extending between the end cap assemblies, wherein end caps of the end cap assembly are removably secured to the roller casing, the roller casing being a composite material comprising at least an inner layer and an outer layer wherein the outer layer has wear resistant properties, whereby the casing's inner layer is aluminium, and the outer layer is carbon steel wherein the carbon steel is sprayed on to the inner layer in the order of 20 microns thick.

34.A conveyor incorporating one or more rollers according to any one of the preceding claims.