Composite shaft for an idler

Abstract

The invention relates to an idler (10), particularly for use in a conveyor belt system, and more specifically to a composite conveyor idler shaft. The idler includes a hollow cylindrical shell (20) and a shaft assembly (30) extending through the shell, wherein the shell (20) is rotatably connected to the shaft assembly (30). At least part of the shaft assembly (30) is formed from a composite material.

Description

[0001] COMPOSITE SHAFT FOR AN IDLER

[0002] BACKGROUND TO THE INVENTION

[0003] THIS invention relates to an idler shaft, and more particularly but not exclusively to a composite conveyor idler shaft for use in a conveyor belt system. The invention also extends to an idler including the new composite shaft.

[0004] A conveyor idler is a component of a conveyor belt system that assists in supporting and guiding the belt of the conveyor belt system. The support typically takes the form of a roller or a series of rollers that are mounted on a frame, or alternately in the form of rollers that are connected in a series by chains, hooks or connecting plates to form a load carrying structure similar to a frame with rollers. The idlers are positioned at regular intervals along the length of the conveyor belt to provide support to the belt and to facilitate its movement. Conveyor idlers come in various types, such as flat idlers, trough idlers, impact idlers, garland idlers and return idlers, each serving a specific purpose in a conveyor belt system. The selection of the appropriate idler type depends on factors such as the type of material being conveyed, conveyor belt specifications, and the operational requirements of the conveyor system.

[0005] A conveyor idler consists of a roller or shell mounted on a steel shaft, with the steel shaft in turn housed within, or supported by, a sturdy frame or in a garland configuration. The roller or shell, often made of a combination of steel and / or coatings including rubber, polyurethane or other polymers, comes in direct contact with the conveyor belt. The shaft supports the roller or shell and allows the roller or shell to rotate smoothly. Bearings at each end of the shaft facilitate rotation of the roller or shell, and are often sealed to prevent contamination. Some idlers include seals or dust covers to protect bearings from environmental elements, extending their lifespan and reducing maintenance requirements.

[0006] The materials and design of an idler can vary significantly depending on the type of idler and the operating conditions of the conveyor system. Conveyor idlers are available with steel shafts and composite (non-metallic) shells or a combination of steel and composite shells. The use of composite materials in the shell offers several advantages, including reduced weight, corrosion resistance, and improved durability against abrasive materials.

[0007] Composite idler rollers are engineered to provide an optimal balance between strength and weight, making them suitable for a range of conveyor applications. The steel shaft ensures the necessary structural support and strength, while the composite shell forms the roller surface that comes into contact with the conveyor belt. This combination leverages the durability and strength of steel for load-bearing functions while benefiting from the lightweight and resistant properties of composites in the roller shell.

[0008] Recently, there has been growing demand to reduce the weight and cost of idlers, particularly in markets with strict weight and handling requirements. However, these reductions must not compromise the performance of the idlers. Despite this demand, existing idlers continue to rely on steel shafts due to essential mechanical and structural requirements, and no clear solutions currently exist for further reducing the weight of composite idlers. It is accordingly an object of the invention to provide an idler that will, at least partially, alleviate the above shortcoming.

[0009] It is also an object of the invention to provide an idler which will be a useful alternative to existing idlers.

[0010] SUMMARY OF THE INVENTION

[0011] According to the invention there is provided an idler, suitable for use in a conveyer belt system, the idler including: a hollow cylindrical shell; a shaft assembly extending through the hollow cylindrical shell; the hollow shell being rotabably connected to the shaft assembly; characterized in that at least part of the shaft assembly is made from a composite material.

[0012] There is provided for the cylindrical shell to be made from a composite material.

[0013] The shaft assembly may include two end sections, and a shaft extending between the two end sections, with the shaft being securable to the two end sections.

[0014] In a preferred embodiment the shaft is hollow. Preferably, the shaft is made from a reinforced polymer composite material, for example a glass- filled polymer.

[0015] In one embodiment there is provided for the tube to be round. In another embodiment the tube may be configured to have a moment of inertia (also known as second moment of area) which is larger about a centroidal x-axis of the tube than about a centroidal y-axis of the tube.

[0016] The tube may be oval, rectangular, or shaped in another form that maximizes stiffness, for example an I-beam.

[0017] In a preferred embodiment each end section has an operatively inner end, configured and dimensioned to engage an open end of the shaft, and an operatively outer end protruding beyond an end of the shell.

[0018] The outer end of the end section may include a bearing seating surface.

[0019] There is provided for the operatively inner end of the end section to engage the hollow shaft by way of a sliding fit.

[0020] The end section is preferably made from a reinforced or unreinforced composite, more preferably from a glass filled polymer.

[0021] There is provided for the end section to be injection moulded or to be machined from a billet.

[0022] In one embodiment, there is provided for the material used to manufacture the end section to include a heat conducting additive in order to increase the heat / thermal conductivity of the end section. Heat is generated by the rotation, load and deflection of the shaft and bearings within the roller and should be dispersed to prevent heat buildup.

[0023] An elongate hole, co-axial with a longitudinal axis of the end section, extends from the operatively inner end of the end section longitudinally into the end section. There is provided for the elongate hole to be a blind hole. The shaft assembly may include an insert configured to fit inside the elongate hole in the end section. The insert may be made from a metal (e.g. a steel rod), or may be made from a suitable high strength polymer (different to the shaft material) having a thermal conductivity which is higher than the material from which the end sections is made.

[0024] A further feature of the invention provides for a reinforcement collar to be located on the shaft in the area where the shaft engages the end section.

[0025] There is provided for the collar to be made from a high strength composite material and / or to be incorporated into the shaft end moulding.

[0026] There is also provided for the idler to include bearings, outer seals and dust covers, as is known in the art.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] A preferred embodiment of the invention is described by way of a nonlimiting example, and with reference to the accompanying drawings in which:

[0029] Figure 1 is a cross-sectional perspective view of an assembled idler in accordance with one embodiment of the invention;

[0030] Figure 2 is a perspective view of the idler of Figure 1 , with one half shown in an exploded configuration;

[0031] Figure 3 is a cross-sectional perspective view of an end section used in the idler of Figure 1 ; Figure 4 is a cross-sectional side view of the end section of Figure 3, as well as a steel insert, an end of a shaft, and a collar, all forming part of the conveyor idler;

[0032] Figure 5 is a cross-sectional view of Figure 2;

[0033] Figure 6 is a perspective view of part of the shaft assembly in accordance with a further embodiment of the invention;

[0034] Figure 7 is a perspective view of part of the shaft assembly in accordance with a further embodiment of the invention;

[0035] Figure 8 is a cross-sectional end view through the shaft of the shaft assembly of Figure 7;

[0036] Figure 9 is a perspective view of an end section in accordance with another embodiment of the invention;

[0037] Figure 10 is a cross-sectional view of the end section of Figure 9; and

[0038] Figure 11 is a cross-sectional view of a shaft assembly incorporating the end sections of Figure 9.

[0039] DETAILED DESCRIPTION OF INVENTION

[0040] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings and are thus intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

[0041] Referring to the drawings, in which like numerals indicate like features, a non-limiting example of an idler in accordance with the invention is generally indicated by reference numeral 10. The idler 10 includes a cylindrical shell 20, and a shaft assembly 30 extending through the shell, and to which the shell 20 is rotatably connected. The idler is suitable for use as a conveyor idler in a conveyor belt system.

[0042] The cylindrical shell 20 is in the form of an elongate, hollow cylindrical sleeve. The shell 20 is made from a composite material for example extruded, molded or pultruded composite ethylenes, polyamides or derivatives of these composites. The cylindrical shell terminates in two opposing open ends 22. The shaft assembly 30 includes a shaft 31 , and two end sections 33 securable to opposing ends 31.1 of the shaft 31. One aspect of the invention provides for the shaft 31 and the end sections 33 to be separate components made from different materials, because the components have to meet different structural different requirements. For example, the end sections 33 support the bearings 60 and are accordingly exposed to different loads compared to the loads exerted on the shaft 31. The end sections 33 are also exposed to more heat emanating from the bearings 60 compared to the heat exposure of the shaft 31. The shaft 31 is in turn exposed to bending moments that the end sections do not have to absorb. The design requirements for the two parts of the shaft assembly 30 are accordingly very different, in particular when manufactured from composite materials, and it accordingly beneficial for the end sections and the shaft to be designed so that they can be made from different materials - something not evident from existing designs. It follows that it is beneficial for the shaft 31 and the end sections 33 to be separate components.

[0043] In the first embodiment of the invention, the shaft 31 is hollow. This means that the same structural strength can be achieved at a reduced weight due to the higher moment of inertia associated with a hollow shaft of larger diameter, but smaller material volume compared to a solid shaft. In this example, the hollow shaft 31 is in the form of a reinforced polymer composite material, and may be in the form of a pultruded resin, glass-filed polymer tube. Pultrusion is a method used to produce continuous lengths of reinforced polymer composite materials with a constant cross-section. This process is commonly used for creating profiles, rods, tubes, and other structural shapes made from reinforced fibers, such as fiberglass or carbon fiber, embedded in a polymer matrix, typically epoxy or polyester resin.

[0044] In the embodiment shown in Figures 1 to 5, the shaft 31 is in the form of a hollow, circular tube. However, other embodiments are foreseen where the shaft may be configured to have a moment of inertia (also known as second moment of area) which is larger about a centroidal x-axis of the tube than about a centroidal y-axis of the tube. For example, as shown in Figure 6, the shaft may have an I-beam profile, or as shown in Figures 7 and 8, may be oval. This is possible because the shaft 31 does not rotate and therefore requires more strength along the y-axis than the x-axis.

[0045] The shaft assembly 30 furthermore includes two end sections 33. In this example, the end sections are made from a suitable composite material (reinforced or unreinforced), for example a glass filled composite material (reinforced or unreinforced). In one embodiment, the end sections are made from 60% glass-filled Nylon. There is provided for the composite material used to manufacture the end section to include a heat transfer additive, for example carbon fiber, in order to improve the heat conductivity of the end sections. This is required in order to assist with the dissipation of heat generated by the bearings 60. The end sections are typically injection moulded.

[0046] Each end section 33 includes an operatively inner end 34 taking the form of an elongate spigot, and an operatively outer end 35 also taking the form of an elongate spigot but extending in an opposite direction. A bearing seating surface 35.1 is provided on the operatively outer end 35 of each end section 33, as this is the end carrying the bearing 60. A shoulder formation 36 is provided between the outer 35 and inner 36 ends.

[0047] An elongate, blind hole 37 extends from the inner end 35 of each end section 33 into the end section and is co-axial with a longitudinal axis of the end section 33, and hence the shaft assembly 30. In use, an insert 40 fits snugly inside the blind hole 37. The insert 40 is typically made from a different material to the rest of the end section, and provides structural reinforcement, but importantly also acts as an additional heat sink for heat conducted from the bearing 50 to the end section 33, and then to the insert 40. The insert may be made from a metal, or may be made from a suitable high strength polymer which has higher thermal conductivity compared to the thermal conductivity of the end section itself.

[0048] A free end 38 of the end section 33 is in use supported by a frame (not shown).

[0049] Reinforcement collars 90 are located on the shaft assembly 30 in the zones where the shaft 31 and the end sections 33 engage, and more particularly where the operatively inner ends 34 of the end sections engage the free ends of the shaft 31 . These collars 90 are in the form of annular sleeves or bushes that fit snugly about the shaft 31 , and which are typically made from a high strength composite material such as Nylon, even though the collars can also be made from various metals, including an alloy such as steel. The purpose of the collar 90 is to protect the shaft assembly 30 against hoop stresses that are generated by the bending moment of the shaft assembly 30 when the idler 10 is loaded. The collar 90 therefore increases the load carrying capacity of the of the idler 10.

[0050] Bearings 60 are used to facilitate the smooth rotation of the roller or sleeve around the shaft assembly 30. They are positioned at each end of the shaft assembly 30, and in particular on the operative outer ends 35 of the end sections 33 of the shaft assembly 30. The bearings are typically in the form of roller or ball bearings, as is known in the art.

[0051] Each bearing 60 fits inside a bearing housing 50, with the bearing housing connecting an operatively outer race of a bearing to the cylindrical shell 20. The bearing housing 50 has an inner end 51 which engages the bearing 60 and an outer end 52 that engages the shell 20. The bearing 60 is enclosed inside the bearing housing 50 by way of a dust seal 70 and a dust cover 80.

[0052] Another embodiment of the invention is shown in Figures 9, 10 and 11. In this embodiment, the collars 90 are integrally formed with the rest of the end sections 33. The function of the collars 90 remain the same as for the previous embodiment, but the injection moulding of the collar with the end section removes a time-consuming step in the shaft production process where the previous separate reinforcing collars would have had to be glued after the end sections are secured.

[0053] The idler described above will be lighter than conventional idlers due to the use of a composite shaft, while still meeting the required structural and heat transfer requirements due to the specific design of the shaft assembly.

[0054] It will be appreciated that the above is only one embodiment of the invention and that there may be many variations without departing from the spirit and / or the scope of the invention. It is easily understood from the present application that the particular features of the present invention, as generally described and illustrated in the figures, can be arranged and designed according to a wide variety of different configurations. In this way, the description of the present invention and the related figures are not provided to limit the scope of the invention but simply represent selected embodiments.

[0055] The skilled person will understand that the technical characteristics of a given embodiment can in fact be combined with characteristics of another embodiment, unless otherwise expressed or it is evident that these characteristics are incompatible. Also, the technical characteristics described in a given embodiment can be isolated from the other characteristics of this embodiment unless otherwise expressed.

Claims

CLAIMS:1 . An idler, suitable for use in a conveyer belt system, the idler including: a hollow cylindrical shell; a shaft assembly extending through the hollow cylindrical shell, the hollow shell being rotabably connected to the shaft assembly; characterized in that at least part of the shaft assembly is made from a composite material.

2. The idler according to claim 1 wherein the cylindrical shell is made from a composite material.

3. The idler according to claim 1 or claim 2 wherein the shaft assembly includes two end sections and a shaft extending between the two end sections, and wherein the shaft is securable to the two end sections.

4. The idler according to claim 3 wherein the shaft is hollow.

5. The idler according to claim 3 or 4 wherein the shaft is made from a reinforced polymer composite material, for example a glass-filed polymer.

6. The idler according to claim 3, 4 or 5 wherein the shaft is round.

7. The idler according to claim 3, 4 or 5 wherein the shaft is oval, rectangular, or shape in the form of an I-beam.

8. The idler according to any one of claims 3, 4, 5 or 7 wherein the shaft is configured to have a moment of inertia which is larger about a centroidal x-axis of the shaft than about a centroidal y-axis of the shaft.

9. The idler according to any one of claims 3 to 8 wherein each end section has an operatively inner end, configured and dimensioned toengage an end of the shaft, and an operatively outer end protruding beyond an end of the shell.

10. The idler according to claim 9 in which the outer end of the end section includes a bearing seating surface.1 1 . The idler according to claim 9 or 10 in which the operatively inner end of the end section is configured to engage the shaft by way of a sliding fit.

12. The idler according to any one of claims 3 to 1 1 wherein the end section is made from a reinforced or unreinforced composite material, preferably from a glass filled polymer.

13. The idler according to any one of claims 3 to 12 wherein the material used to manufacture the end section includes a heat conducting additive in order to increase the thermal conductivity of the end section.

14. The idler according to any one of claims 3 to 13 in which an elongate hole, co-axial with a longitudinal axis of the end section, extends from the operatively inner end of the end section longitudinally into the end section.

15. The idler according to claim 14 wherein an insert is located inside the elongate hole in the end section.

16. The idler according to claim 15 wherein the insert is made from a metal.

17. The idler according to claim 15 wherein the insert is made from a high strength polymer that has a thermal conductivity higher than the thermal conductivity of the end section.

18. The idler according to any one of claims 3 to 17 including a reinforcement collar located on the shaft in the area where the shaft engages the end section.

19. The idler according to claim 18 wherein the collar is made from a high strength composite material.

20. The idler according to claim 18 wherein the collar is integrally formed with the shaft end.

Images