An End Ring for a Sleeve, a Sleeve adapted to receive such an End Ring, and a Sleeve Assembly incorporating such an End Ring

Abstract

A sleeve assembly in which a pair of annular end rings are screwed into respective ends of an annular sleeve which includes around its inner surface a compressible liner. Respective surfaces of both end ring and sleeve are provided with specific complementary groove, chamfer, undercut or channel formations, and prior to screwing insertion of an end ring into a sleeve end, respective surfaces and formations are filled and covered with a viscous but fluent curable gasket forming composition such that amounts of gasket forming composition provided on and continuously around the end ring unite with corresponding amounts of gasket forming composition provided within and completely around corresponding surfaces of the sleeve as and when the end ring is completely screwed into a sleeve end. When the respective amounts of gasket forming composition provided on end ring and sleeve unite together and cure, effective rib or band-like rubberized seals are created.

Claims

1. A sleeve assembly comprising a pair of annular end rings and an annular sleeve in each end of which said end rings are substantially disposed, said sleeve being provided internally with an annular radially compressible liner substantially symmetrically disposed within said sleeve between the end rings and being of a length such that the annular end surfaces of said liner are disposed proximate and adjacent the innermost annular end surfaces of said end rings, said liner being adhered or otherwise affixed to the interior cylindrical surface of the sleeve around its outer cylindrical surface, each of said end rings having both an exterior generally cylindrical surface which extends axially and is, in use, disposed adjacent a corresponding interior generally cylindrical, axially extending surface of said sleeve, and an inner annular end surface which extends radially and is, in use, disposed adjacent a corresponding annular and radially extending end surface of said liner, said outer cylindrical surfaces of said end rings, in first portions thereof, being provided with or functioning as connection means which interact with corresponding portions of the cylindrical surfaces of the sleeve and whereby said end rings are secured to and substantially within said sleeve at either end thereof, second portions of said outer cylindrical surfaces of said end rings being those portions thereof axially outwith the first portions, wherein: At least one of said end rings is provided with at least one continuous excavation formation in at least one of: the second portion of the outer cylindrical surface of said end ring, in which case said continuous excavation formation depends radially inwardly of the end ring, and said inner annular end surface of said end ring, in which case said excavation formation depends axially within said end ring away from said inner annular end surface thereof, And a corresponding continuous channel is provided in at least one of: The corresponding cylindrical surface of the sleeve adjacent which the outer cylindrical surface of the end ring is, in use, disposed, and The corresponding annular end surface of the liner adjacent which, in use, the inner annular end surface of the end ring is disposed, The respective axial and/or radial dispositions of said end ring excavation formation and the corresponding continuous channel provided in one or both of the sleeve or the liner being such that, when the end ring is fully inserted within and secured to the sleeve, said at least one excavation formation of the end ring and said corresponding continuous channel of the sleeve and/or liner axially and/or at least partially radially overlap whereby an amount of an initially fluent curable gasket forming composition deposited substantially within or over said at least one end ring excavation formation can unite with a corresponding gasket or amount of gasket forming composition disposed in said corresponding continuous channel provided in the sleeve or the liner so as to form, once the initially fluent curable gasket forming composition cures, one or both of: A continuous annular barrier seal which extends radially across the interstice defined between adjacent corresponding cylindrical surfaces of end ring and sleeve, and A continuous rib barrier seal which extends axially across the interstice defined between adjacent corresponding annular end surfaces of end ring and liner.

2. An assembly according to claim 1, wherein the excavation formation provided on the end ring is one of: a channel, a groove, depression, notch and a chamfer and the gasket forming composition is applied thereto in such a manner that some amount of the applied gasket forming composition becomes therewithin.

3. (canceled)

4. An assembly according to claim 2, wherein the gasket forming composition is applied at least to the excavation formation in such a manner that it both partially or completely fills the excavation formation with some excess amount of said gasket forming composition overtopping said excavation formation.

5. An assembly according to claim 1, wherein the first portion of the outer cylindrical surface of both end rings is provided with threads, and the corresponding interior cylindrical surfaces of the sleeve, at either end thereof, are correspondingly tapped such that the end rings may be screwed into the sleeve ends and secured therein.

6. An assembly according to claim 1, wherein one or both end rings are provided with an excavation formation in the form of a continuous undercut channel in the second portion of their outer cylindrical surfaces, and the sleeve is provided with corresponding continuous undercut channels at either end, internally thereof, in the corresponding cylindrical surfaces of said sleeve.

7. An assembly according to claim 1, wherein a radially innermost portion of the annular end surface of the sleeve is rebated radially outwardly towards the exterior cylindrical surface of the sleeve such that an annular shoulder is defined within the annular end surface of the sleeve, said annular shoulder providing a contact surface which supports, and against which abuts, a corresponding peripheral annular surface of an underside of a radially outwardly projecting lip of the end ring upon full and complete insertion of said end ring into an end of the sleeve, said annular shoulder providing a means whereby the axial travel of said end ring into and within an end of the sleeve is restricted.

8. An assembly according to claim 5, wherein the extent of axial travel of the end ring within the sleeve as it is rotated during screwing connection of the former to and within the latter is mechanically limited by respective surfaces of end ring and sleeve coming into abutting contact with one another, whereby the innermost annular end surface of the end ring is automatically disposed proximate and adjacent an annular end surface of the liner adhered within the sleeve, but separated therefrom by an axial distance being one of: less than 3 mm, between 1.5 mm and 3 mm, and between 0.2 mm and 1.5 mm.

9. An assembly according to claim 1, wherein the inner diameter of the end ring is preferably greater than the inner diameter of the liner by an amount in the range of 0.1-1% of the total inner diameter dimension of the end ring.

10. (canceled)

11. An assembly according to claim 1, wherein the gasket forming composition is initially a viscous but fluent liquid which subsequently cures into a rubberised, elastic waterproof and chemically resistant elastomer.

12. An assembly according to claim 1, wherein, prior to insertion and mechanical connection of any end ring within a sleeve end, an amount of gasket forming composition is applied completely over any and all those exterior and interior surfaces, respectively, of one or both of the end ring and the sleeve which ultimately come into contact with one another, or become proximately and adjacently disposed with one another as a result of the insertion into and mechanical connection of the end ring within an and of the sleeve.

13. An assembly according claim 1, wherein one or both of the second portion of the exterior cylindrical surface of the end ring, and the interior annular end surface of the end ring may be provided with a further excavation formation, axially distinct and separated from any other excavation formation provided in such surface, said further excavation formation not having any dispositionally matched further continuous channel provided in the corresponding adjacent surfaces of sleeve or liner.

14. An assembly according to claim 13, wherein the radial position of a first matched excavation formation and the dimension of the opening thereof are selected such that radially, a compressible layer of the liner and the continuous channel provided substantially within it is disposed entirely and completely radially inwardly of the further excavation formation, which is thus more radially distant from a central axis of the sleeve assembly than said compressible layer.

15. (canceled)

16. An assembly according to claim 1, wherein the excavation formation takes the form of a continuous groove which is provided in and around the innermost annular end surface of at least one end ring, and the liner is provided with a corresponding continuous channel excavated from at least one annular end surface thereof.

17. An assembly according to claim 16, wherein the liner component provided within the sleeve is a multi-laminar liner wherein at least one of the lamina is a compressible layer, and the continuous channel provided in the liner is created by substantially excavating said compressible layer to a uniform depth.

18. An assembly according to claim 1, wherein the excavation formation takes the form of a continuous chamfer which is provided around an end ring between, firstly, the axially innermost annular end surface thereof, and secondly, an axially innermost portion of the axially extending cylindrical surface thereof, and the sleeve is provided with a corresponding continuous channel at a suitable axial position inside the sleeve so that when said end right is screwed fully and completely into an end of the sleeve, the chamfer on the end (s) ring and continuous channel within the sleeve are to some extent axially coincident with one another inside the sleeve assembly as a whole.

19. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0070] FIG. 1 shows an exploded perspective view of one end of sleeve forming part of the prior art, and an end ring, also of known configuration, adapted for screwing insertion into said sleeve end,

[0071] FIG. 2 shows a side elevation of an end ring according to one embodiment of the present invention,

[0072] FIG. 3 shows a condensed sectional elevation of a sleeve assembly according to the invention, comprising the end ring of FIG. 2 fully and completely screwed into one end of a sleeve according one embodiment of the present invention,

[0073] FIGS. 4A, 4B, and 4C show various partial sectional elevations the end ring of FIG. 2 and a sleeve according to one embodiment of the present invention at different stages of insertion of the end ring into an end of the sleeve and securing therein, and

[0074] FIGS. 5, 6 shows an enlarged partial sectional elevation of a sleeve assembly according to embodiments of the present invention, both Figures in particular showing one end of a completed sleeve assembly, and different possible configurations of the groove embodiment of the invention.

DETAILED DESCRIPTION

[0075] Referring firstly to FIG. 1, there is shown an exploded perspective view of a sleeve assembly of known configuration, in which a sleeve, generally indicated at 2, and corresponding end ring 4 are illustrated. An open end 6 of the sleeve is illustrated prior to screw-fitting insertion of the end ring 4 therein. The sleeve 2 is tubular and cylindrical. The primary structural component of the sleeve itself is an annular aluminium or steel tube 8 (which in this Figure is not shown with any coating or printing plate layer yet applied or affixed to the exterior surface for clarity, but which is in practice is commonly required).

[0076] The open end 6 of the tube 8 is internally rebated so that: [0077] the internal diameter of the tube in the end region is enlarged as compared to the internal diameter of the tube axially beyond the depth of the rebate, [0078] the wall thickness of the tube in the end region is reduced as compared to the wall thickness elsewhere along the tube, and [0079] an internal shoulder 14 is defined in the tube at some short distance axially inside the tube (typically of the order of 5-25 mm) remote from the open end 6.

[0080] Thus, after internal rebating, an outermost radial annular surface 10 is provided which defines an opening which receives a correspondingly shaped and sized tubular shank portion 12 of the end ring 4, and axially inwardly of the open end 6, there is provided shoulder 14 which an outer portion of the end-most radial planar surface of said end ring shank portion 12 preferably ultimately abuts as the said shank portion is fully received in the sleeve open end 6. The rebating process also further defines an axial inner surface 16 in the sleeve open end, and as is shown in the Figure, screw thread formations 18 are ideally provided in the axially innermost region of said axial inner surface 16, and corresponding screw threads 20 are provided towards the free axial end of the shank portion 12 of the end ring on the outermost axial surface thereof. By such means, not only can the end ring 4 be received within the open end 6 of the tube 8, but it can be exceedingly firmly secured therein.

[0081] Although this specific description is only concerned with end rings which are screwingly secured within the open ends of their corresponding sleeves to create the sleeve assembly, the skilled reader should understand that the present invention need not be limited by the particular form and type of fixing by means of which the end ring is firmly secured to and within the sleeve. Indeed, the only requirement, as far as the present invention is concerned is that both sleeve and end ring have respective fixing surfaces, provided at similar axial depths from the respective annular end surfaces of both sleeve and end ring, and it is these surfaces which either mechanically interact with one another (in the case of screw threads and common interference fit connections), or are otherwise are, or become, secured to one another, for example if a high strength epoxy or other adhesive is to be used as the fixing means. Importantly, as far as the present invention is concerned, it is the interface between the respective cylindrical surfaces of sleeve and ring which is often prone to operative liquid ingress, and indeed the present invention has as one of its primary objects a means of limiting or possibly even precluding the ingress of operative liquid into this interface from externally of the sleeve assembly, as will be further described hereinafter.

[0082] As may also be seen in FIG. 1, the end ring 4 is provided with a peripheral flange 22 which effectively enlarges the outermost diameter of the end ring in its axially outermost region. In the illustrated embodiment, the radial dimension of said flange 22 is exactly the same as the radial dimension of the outermost radial annular surface 10 so that, once the end ring is fully received and screwed into the open end 6, said flange abuts said radial annular surface 10 in planar mating fashion and thus defines a barely visible seam therebetween. As will become apparent from the following description, however, alternate arrangements are possible.

[0083] In terms of the interior of the tube 8, as is common for sleeve assemblies of the type with which the present invention is concerned, multiple further layers are provided around the innermost axial cylindrical surface of the tube, and in the Figure, three such layers are referenced at 30, 32, 34. In order to render the sleeve assembly internally expandable to at least some degree, at least one such layer must be formed from a material which is relatively dimensionally much less stable than the aluminium (or steel) of which the sleeve itself is primarily constructedit is this layer that renders the liner radially compressible to some degree, and is thus often terms the compressible layer.

[0084] Specifically, in most common known arrangements, the liner is constituted of three layers. The first, radially innermost layer 30, known as the base wrap layer, is commonly made from a fibreglass-type material, or in some cases, a glass (or other) fibre reinforced plastics or polymer material. To the cylindrical radially outer surface of layer 30 is then provided a compressible layer 32, which is most often of an open- or closed-cell foam, foam-like or sponge-like composition, such as, for example any polymer foam (e.g. polyurethane foam). To the radially outer surface thereof is provided further layer 34, commonly known as a composite build-up layer which is usually fibrous and absorbent. In the simplest liners, an inexpensive matting material such as coir mat is used, which is firstly dipped, submerged or otherwise impregnated with an epoxy resin which is largely absorbed into the matting layer which can then be wrapped around the exterior surface of the compressible layer, after the adhesive or epoxy with which it is impregnated is then cured. It is the radially exterior-most cylindrical surface of this layer which interfaces with the innermost axial surface of the tube 8. Most commonly, liner is adhesively bonded to the interior cylindrical surface of the tube 8. Liners such as described are prefabricated items with all their respective layers already bonded together, and may have an overall annular thickness of maybe only 8-25 mm, depending on application and the diameter of the tube inside which they are to be bonded. The typical thickness of layer 30, being always the thinnest layer, is no more than 2 mm, and often this layer may be as thin as 0.4-1.5 mm. In some applications, the layer may be only 50-400 microns thick. The compressible layer 32 may be 3-8 mm thick, with the outermost layer 34 being the thickest, at maybe 4-15 mm.

[0085] Referring now to FIG. 2, there is shown a side elevation of a modified end ring, indicated generally at 40 according to one embodiment of the present invention. Although other views are not provided, the skilled reader will immediately understand that this end ring is essentially similar in shape and size to that illustrated in FIG. 1, in that the end ring is essentially an annular component with a uniform inner diameter .sub.1, an outer diameter .sub.2, with the average diameter of the threaded portion being .sub.3, as shown in the Figure, such that the annular end surface 42 is of a thickness (.sub.2-.sub.1)/2, whereas the axially innermost (in use) generally annular end surface 44 is of a thickness (.sub.3-.sub.1)/2.

[0086] In the interests of brevity, all of FIGS. 2, 3, 4A, 4B, 4C, 5 and 6 illustrate an embodiment of the invention which includes all of: the undercut, groove and chamfer embodiments of the invention. It should of course be understood that only one or two of these embodiments need necessarily be provided, or some combination thereof, but it is most preferred that at least the chamfer and groove embodiments be present.

[0087] For the sake of explanation and consistency of terminology, it is useful to notionally axially divide the end ring 40 along dotted lines 46A, 46B, such that the first axial portion 50 of the end ring is that portion which lies between these dotted lines, and the second portion of the end ring is that which lies outside them, indicated in this FIG. at 48A, 48B, with 48A being axially outermost and 48B being axially innermost. This language corresponds to that used herein in the statements of invention above and/or the claims of the application appearing hereinafter.

[0088] Thus the first portion 50, and in particular the exterior cylindrical surface thereof, in this embodiment at least, is provided with threads 52. The second portion 48A is provided with a radially projecting lip 54 which projects radially beyond the radial extent of the second portion 50 of the end ring (that is, .sub.2>.sub.3) and second portion 48B, in contrast is provided with a chamfer 59. As can be seen in the figure, the radially innermost portion (beneath this radially projecting lip) is provided with a continuous undercut channel 56, completely around the end ring behind lip 54. As can be seen in the Figure, the base (not referenced) of the undercut channel has a diameter dimension which is less than .sub.3. Example axial thickness dimensions of 3 mm, 1 mm, and 5-25 mm for each of the axial thickness (or depth) of the radially projecting lip, the axial thickness (or width) of the undercut channel, and the axial thickness (or depth) of the threaded second portion respectively are also provided in the Figure. Example dimensions for (.sub.1, .sub.2 and .sub.3 are provided elsewhere within this specification. All dimensions will of course depend fundamentally the nature of the machine and application in which the sleeve assembly of the present invention is to be used, and in most cases, the determining dimensions is (1) the required exterior diameter of the sleeve assembly as a whole, and (2) the overall axial length of the sleeve assembly, both these often being primarily determined by the length and diameter of the air or bridge mandrel onto and from which the sleeve assembly is to be mounted and dismounted.

[0089] The end ring 40 is, in the particular embodiment illustrated, provided with a continuous circular channel or groove 58, having a typical radius dimension of only a few mm, e.g. 1-5 mm, in the, in use, axially innermost annular end surface 44. The lateral positioning, that is the radial or diametral dimension of said groove or channel is important as will further be described below, but in most embodiments, the said groove or channel will be disposed radially outwardly of the innermost cylindrical surface of the end ring and spaced from said surface by only a few mm, this spacing typically being the same as, or slightly greater than, the thickness of the innermost fibreglass layer of the liner (see additional description below). In particular, the most preferred diametral dimension of the said groove or channel is such that the groove is disposed exactly radially above the compressible layer, or slightly radially outwardly offset therefrom, as can be seen in FIG. 3 and subsequent Figures.

[0090] In this FIG. 3, a sleeve assembly 60 according to the present invention is illustrated and referenced generally at 60, and comprises an annular sleeve 62, typically of Aluminium or Steel, but other metals, alloys or plastics composite materials may be considered, a multi-laminar liner indicated generally at 64 and typically adhesively bonded to the interior cylindrical surface 62-1 of the sleeve, as is well known. As the skilled reader will understand from the Figure, only one end of the entire sleeve assembly is illustrated, but in most embodiments, it can be presumed that the alternate end is of identical configuration. As previously discussed, liner 64 comprises at least three distinct layers, 64A, 64B, 64C, being, respectively, a fibre-glass base wrap layer, a cellular foam compressible layer, and a composite and/or fibrous build-up layer, all of increasing annular thickness. Finally, the sleeve assembly 60 includes an end ring 40, as described above with reference to FIG. 2, fully and completely screwed into the illustrated end of the sleeve 62, and occupying its final axial position therein.

[0091] In the position illustrated, it is important to understand certain dimensional and positional aspects of the end ring, relative to other components of the sleeve assembly. Firstly, as can be seen from the Figure, the diametral dimensions of the layers 64A, 64B, 64C of the liner 64 are referenced at .sub.L1, .sub.L2, .sub.L3 and .sub.L4 respectively, and in order for any radial compression of the liner to occur at all, the interior cylindrical surface of the liner 64, and thus layer 64A, must lie within the adjacent cylindrical surface of the end ring, that is it is essential that .sub.L1<.sub.1, typically by a tiny amount, e.g. 0.2-1 mm, and most commonly about 0.7 mm. Secondly, in this embodiment, it can be seen that the groove or channel lies entirely radially beyond the innermost diametral dimension of the compressible layer 64B of the liner, that is the diametral dimension .sub.G of the groove, less the radius dimension of the groove itself (not illustrated, but herein r.sub.G) are such that the following relation holds:

[00001]${}_{L2}<\left({}_G-2r_G\right)<{}_{L3}$

(or in some embodiments, .sub.L2(.sub.L2-2r.sub.G).sub.L3)
In other words, the groove or channel must radially overlap at least some portion of the compressible layer (and specifically the continuous channel provided therein, as further explained below) of the liner, by at least some extent.

[0092] Indeed, the most preferred arrangement is defined by the following relations:

[00002]$\left({}_G+2r_G\right)={}_{L3}\mathrm{and}\left({}_G-2r_G\right)={}_{L2}$

(i.e. the groove or channel exactly overlies the compressible layer of the liner, or the continuous channel provided therein/excavated therefrom).

[0093] In certain preferred embodiments of the invention, in particular those where a further continuous channel or groove which is unmatched with a corresponding channel in the annular end surface of the liner, then one or more other relationships might apply, for example: [0094] (1) (.sub.G-2r.sub.G)>.sub.L3 (the radially innermost edge of the groove lies radially to the outside of the outermost diametral dimension of the compressible layer 64B of the liner 64) [0095] (2) (.sub.G-2r.sub.G)=.sub.L3 (the radially innermost edge of the groove lies radially coincident with the outermost diametral dimension of the compressible layer 64B of the liner 64) [0096] (3) (.sub.G=2r.sub.G)>.sub.L3 (at least some portion of the groove lies radially beyond the outermost diametral dimension of the compressible layer 64B of the liner 64) [0097] (4) .sub.G=.sub.L3 (the diametral dimension of the groove is the same as that of the radially outermost surface of the compressible layer 64B so that the groove lies symmetrically above the interface between the 64B and composition/fibrous build-up layer 64C) [0098] (5) (.sub.G+2r.sub.G)<=.sub.3 (the radially outermost edge of the groove lies radially to the inside, or adjacent the threaded portion of the end ring), or [0099] (.sub.G+2r.sub.G)>.sub.3>(.sub.G-2r.sub.G) (the radially innermost edge of the groove lies radially to the inside the threaded end portion of the end ring; in this case, the groove would be more akin to a radially inward chamfer between the threaded portion of the end ring, thus reducing the axial length of the threaded portion, and the annular end surface of the end ring; indeed, as shown in FIG. 5, this chamfer be employed together with a groove as above defined and described, to provide additionally sealing robustness).

[0100] In all cases, however, the groove must lie within the annular end surface 44 of the end ring, so [0101] (.sub.G-2r.sub.G)>.sub.1 will generally always apply. A typical dimension for re may be of 2-4 mm, but this will of course depend on the relative annular thicknesses of the layers within the liner, and the radial extent of chamfer 59, which may be order of 1-6 mm.

[0102] The radial position of the groove is important and principally arises from its desired function, namely, when filled with gasket forming composition which subsequently cures to form a sealing gasket, such curing also unites the gasket forming composition present within the groove with the gasket or cured or uncured gasket forming composition already present within a corresponding or matched continuous channel provided in the annular end surface of the liner, referenced in FIG. 3 at 64N, at least to some extent. When provided, said channel 64N is most preferably between about 5-8 mm in depth, and is both completely dry and clean from any debris, dust, or other particulate matter or detritus which remain therein after the milling, routing or boring tool has completed excavating said channel, as clean dry surfaces aid the bonding efficacy of the curable elastomeric compound deposited with said channel to the base and sides thereof. Furthermore, it is particularly preferable that the channel is excavated in the membrane, and optionally also some radially proximate part of the exteriorly disposed outer buildup (coir mat) layer of the liner, to a substantially or precisely uniform depth from the annular end surface of the liner, and that this channel is then completely filled with the curable polymeric and/or elastomeric composition.

[0103] Thus, firstly, as the end ring is screwed into the end of the sleeve, the gasket forming composition present in the groove comes into contact with, and indeed is smeared all over and around the gasket or gasket forming composition present within the matched continuous channel of the liner so as to create a quasi-unitary axially extending seal structure, albeit one which has not yet solidified. Once the end ring is fully screwed in place, and the sleeve assembly left undisturbed, the gasket forming composition cures and in doing so become essentially united with the gasket or gasket forming composition present in the matched continuous channel of the liner, and thus a band or ribbon of gasket is created which extends axially towards the end surface of the sleeve assembly from the base of channel 62N and into the roof of groove 58, and in substantially cylindrically continuous fashion. This axially disposed barrier seal thus completely prevents fluid from travelling radially past it, from either direction, as is better illustrated in FIGS. 4A, B, C.

[0104] Of course, and as will be described further below with reference to said FIGS. 4A, B, C, the corresponding threaded portions of both end ring and sleeve will normally have some sealant or gasket forming composition applied thereto so that when the former is screwed into the latter, the sealant is smeared substantially around, into and within the threads and upon curing, creates a substantially complete seal. However, the perfection of this seal can not be guaranteed, and in any event the amount of sealing composition which exists between the screw threads is so miniscule that it can easily disintegrate, either physically as a result of the high speed rotation and vibrations to which the sleeve is subjected during use, or chemically as a result of the chemical reaction with or dissolution in any operative liquid which manages to make its way through to the screw thread interface region between end ring and sleeve.

[0105] As can also be seen in FIG. 3, a further feature of sleeve 62 is a continuous undercut channel 62A which, in similar fashion to the undercut channel 56 of the end ring (to which it is, in the language of this specification axially matched), is routed out from the interior cylindrical surface of the sleeve at an axial depth beneath an annular end surface 62B of the sleeve which is similar to the axial depth of undercut channel 56 beneath the annular end surface 42 of the end ring 40. The effect of this undercut channel 62A is to define, axially above it, a radially inwardly projecting lip 62C on the sleeve. By this arrangement, and as illustrated in FIG. 3, when the end ring is completely and fully screwed into an open end of the sleeve, the undercut channels 56, 62A of both end ring and sleeve are substantially axially aligned, or at least axially overlap to at least some degree, such that a sealing gasket or gasket forming composition (not illustrated in FIG. 3 but shown and described in greater detail below with reference to FIGS. 4A, B, C) provided in one or both undercut channel can effectively sealingly bridge across the circular opening 68 to the interface between screw threaded portions of end ring and sleeve axially below said opening. As such, this radially extending sealing bridge or barrier provides a very effective means of preventing or at least substantially limiting, operative liquid ingress axially beyond said bridging or barrier seal.

[0106] Finally in FIG. 3, a further feature of sleeve 62 is a continuous channel 62X which is broadly similar to continuous undercut channel 62A above, except of course that it is disposed axially more deeply within the sleeve so as to be substantially if not exactly axially matched with chamfer 59. Thus as illustrated in FIG. 3, when the end ring is completely and fully screwed into an open end of the sleeve, the undercut chamfer 59, and continuous channel 62X of end ring and sleeve respectively are substantially axially aligned, or at least axially overlap to at least some degree, such that a sealing gasket or gasket forming composition (not illustrated in FIG. 3 but shown and described in greater detail below with reference to FIGS. 4A, B, C) provided both over the chamfer 59 of the end ring and in continuous channel 62X can effectively sealingly bridge across the seam between the most exterior cylindrical surface of the liner and the adjacent cylindrical surface 62 of the sleeve. As such, this radially extending sealing bridge or barrier provides a very effective means of preventing or at least substantially limiting, operative liquid ingress axially beyond said bridging or barrier seal into said seam.

[0107] Referring now to FIGS. 4A, 4B, 4C, in which the reference numerals used in FIG. 3 are also used to reference similar components, features and parts thereof, prior to screwing (or other, e.g. interference fit) insertion of end ring 40 into and within an open end of sleeve 62, in this particular embodiment, amounts of initially fluent but ultimately curable gasket forming composition 80, 82, 84 are applied, manually or mechanically, to the exposed cylindrical surfaces of both end ring and sleeve, such being disposed to the exterior of the end ring and to the interior for the sleeve. In FIG. 4A, amounts 80, 82 are shown separate, but of course they may be applied such that they form a single axially and circumferentially continuous amount of composition. Furthermore, although undercut channel 56 is shown, in this embodiment at least, without any significant amount of composition present therein, this may not be the case, and the undercut channel 56 may of course be completely or partially filled with composition. Indeed, in most preferred embodiments, both undercut channel 56 and groove 58 are specifically and substantially filled with curable gasket forming composition. In some embodiments, the fluent gasket forming composition is applied to only one or other of the end ring and the sleeve, but whatever the application methodology, the aim of such is to ensure robust seals as follows: [0108] (1) within annular space defined by respectively aligned or matched undercut channels 56, 62A of end ring and sleeve respectively when the former is fully and completely screwed into the latter, such seal bridging across the opening 68 (see FIG. 3) [0109] (2) within annular space defined by respectively aligned or matched chamfer 59 and continuous channel 62X of end ring and sleeve respectively when the former is fully and completely screwed into the latter, such seal bridging across the circular join seam between the exterior cylindrical surface of the liner and the corresponding adjacent inner cylindrical surface of the sleeve to which it is adhered (see FIG. 3) [0110] (3) within the continuous groove or channel 58 and within corresponding substantially radially aligned matched continuous channel 64N provided in the liner, such that both are essentially filled, [0111] (4) against the adjacent and proximate annular end surface of the liner, including at least some annular end surface portion of the composite and/or fibrous build-up material layer of the liner, [0112] (5) Between the axially innermost annular end surface of the end ring and whatever portion of the annular end surface of the proximate and adjacent liner is radially covered by that end ring annular end surface (as described above, not all the liner annular end surface is completely radially covered) [0113] (6) Between and within the respective threaded portions of end ring and sleeve, [0114] (7) Between all other circumferentially proximately, and adjacently disposed cylindrical surfaces of end ring and sleeve, and [0115] (8) Between any and all other radially extending surfaces of end ring and sleeve which are disposed proximate one another or abut one another when the end ring is fully and completely screwingly completely inserted within the end ring.

[0116] Thus, in the embodiment illustrated in FIG. 4A, sufficient gasket composition is shown as having been applied to achieve all the above aims, though for the purposes of the present invention, only one or more of aims (1), (2), (3) above are considered as being essential.

[0117] It is worth mentioning here also that in some preferred embodiments, only initially fluent curable composition is used from the outset, and the end ring(s) are screwed into the ends of the sleeve when all of the gasket forming composition used has not yet cured, and is still in an essentially fluent or fluid state.

[0118] Referring now to FIG. 4B, end ring 40 is shown in a stage of partial insertion into the open end of the sleeve 62. As can be seen, and as the skilled reader will understand, the insertion procedure causes deformation and coalescence of the various amounts 80, 82, 84 of fluent curable gasket forming composition, such effectively uniting and becoming one continuous mass. Naturally, some of the gasket forming composition will flow and be squeezed into, between and from the various respective surfaces, channels and grooves of one or both of the end ring and the sleeve. For instance, amounts 80, 84 will coalesce to some degree, and any surfeit of composition will be squeezed from between the radially outwardly projecting lip 54 of the end ring 40, and the proximally and adjacently disposed radially inwardly projecting lip 62C of the sleeve, ultimately forming a circular bead of composition immediately the interstice formed betwixt the two. Similarly, amounts of fluent gasket forming composition 82, 84 will ultimately coalesce between the axially innermost annular end surface of the end ring and the annular end surface of the liner, with any surfeit of composition being squeezed radially inwardly from the interstice ultimately defined between these two surfaces, thus creating a similar circular bead of composition around the inside of the sleeve assembly in the region of said interstice.

[0119] The result in the completed sleeve assembly is shown in FIG. 4C, in which the now coalesced amounts of fluent gasket forming composition referenced at 80/84 and 82/84 can clearly be seen. Naturally, where a fluent gasket forming composition is used, it is normal practice to wipe away any beads of excess composition which form as a result of the connection of the end ring within the sleeve immediately thereafter, and before the gasket forming composition is allowed to cure.

[0120] Certain additional aspects of the present invention are illustrated in FIGS. 4A, B, C. Firstly, it is to be noted that the radially inwardly projecting lip 62C of sleeve 62 is dimensioned so that its innermost cylindrical or axial surface has a minimum inner diameter which is greater than that of the minimum inner diameter of the threaded portion of the sleeve, such that some portion, e.g. 0.5-2 mm, of the axially innermost sidewall which defines the undercut channel 62A projections radially inwardly beyond the radially inwardly projecting lip. This allows or at least promotes any amount 84 of fluent gasket forming composition applied into and within undercut channel 62A to be axially visible to the approaching end ring, and thus firstly permits or promotes coalescence with any amount 80, 82 applied to the end ring, whereafter further axial travel of the end ring causes the coalesced amount of fluent composition to be plastically deformed or otherwise forced further into said undercut channel by the relative axial movement between end ring and sleeve as the former is inserted into and secured within the latter. Similarly, amounts of fluent composition on the end ring, and in particular in or within the undercut channel 56 thereof, would be similarly deformed or otherwise forced deeper into that undercut channel. The result of these interactions is to ensure that a coalesced mass of fluent composition is created within both undercut channels of end ring and sleeve respectively, said coalesced mass extending from the undercut channel of the end ring across and into the undercut channel of the sleeve, and thus across and over the circular opening to the threaded interface region axially beneath said undercut channels, and so providing an effectively seal therefor and thereover.

[0121] A further feature of the present invention, provided in some embodiments, and illustrated in FIGS. 3, 4A, 4B, 4C, is the radially outward rebating of radially inwardly projecting lip 62C of the sleeve 62 to a depth less than the axial depth of the lip itself so as to define an abutment annular shoulder 62D against which a radially outermost portion of the underside of the radially outwardly projecting lip 54 of the end ring comes into contact with and abuts against when the end ring is being screwed into the sleeve. As the skilled reader will immediately understand, this shoulder 62D effectively limits the extent of axial travel of the end ring relative to the sleeve, and determines the final relative axial position of the former relative to the latter. As can also be seen in FIGS. 3, 4C, when the end ring is fully and completely inserted and secured within the sleeve, the annular end surface 42 of the end ring 40 stands slightly axially proud and above the adjacent annular end surface 62B of the sleeve 62. In practically all circumstances, this proud-standing amount is subsequently machined off, for example by grinding, so that the resulting annular end surface of the end ring lies precisely flush with the annular end surface 62B of the sleeve, and the overall length of the sleeve assembly as whole can be exceedingly precisely defined.

[0122] Referring finally to FIGS. 5, 6, an enlarged portion of a sleeve assembly 60 is shown in which the various salient features of the invention already described above can be more clearly seen. In particular, the relative dimensions and axial dispositions of chamfer surface 59 provided on the end ring and the corresponding continuous channel 62X provided in the sleeve can be seen, at least in the specific one embodiment illustrated (other dimensional and relative axial dispositions may of course be possible). Thus, the chamfer 59, together with corresponding continuous channel 62X, have the combined effect of creating an additional radially extending region 59A which may be occupied by a gasket or gasket forming composition, which may thus provide additional sealing benefits, particularly as regards any operative liquid which has managed to penetrate seals disposed axially above and earlier in the potential axial fluid ingress pathway. In particular, once the initially fluent gasket composition provided over the chamfer 59 and within the corresponding continuous channel 62X cures, this creates, in effect, an annular, radially extending barrier seal which directly resists fluid ingress into the circular join seam between the liner and the sleeve which lies immediately beneath it. Furthermore, applicant believes that the existence of this particular annular barrier seal further inhibits fluid ingress, beyond said annular barrier seal, radially inwardly and towards the compressible layer of the liner. In FIG. 5, 6, it is to be noted that the axial depth and position of the channel 62X is such that (a) it's axially deepest edge lies flush with the annular end surface of the liner, and (b) the axial overall depth of the channel is such that its axially shallower upper edge lies substantially axially coincident with the axially shallowest edge of chamfer 59. Of course, other arrangements are possible: for example, the channel 62X may be have an axial disposition and depth such that (a) it's axially deepest edge lies flush with the axially deepest edge of the chamfer 59 of the end ring, and (b) the axial overall depth of the channel is such that its axially shallower upper edge lies substantially axially coincident with the axially shallowest edge of chamfer 59. The skilled person will of course realise many other possible configurations all of which lie within the scope of the present invention, provided that, axially, the said chamfer 59 and said channel 62X overlap at least to some degree.

[0123] Additionally, FIGS. 5, 6, different possible configurations and arrangements of the groove 58 and matched continuous channel 64N are illustrated. Specifically, in FIG. 5, both groove 58 and channel 64N or relatively smaller, with the groove being disposed marginally radially outwardly of the channel 64N, but largely overlapping it. In FIG. 6, both groove 58 and channel 64N are relatively larger, and although the relative radial disposition of both is similar, it is to be noted that the channel 64N provided in the end surface of the liner 64 is formed by excavating both the compressible layer and a portion of the coir mat build-up layer. In some embodiments, this is a preferred configuration as it effectively radially outwardly displaces the radially outermost surface of the barrier seal as a whole, which effectively renders it even more difficult for an fluid migrating radially inwardly along the interstice between the end ring and the liner in the direction of the compressible layer because such fluid now encounters the barrier seal earlier in its travel, and at a position which is effectively more remote from the compressible layer.

[0124] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.