WO2020239843A1

WO2020239843A1 - A compressible liner, a method of manufacture thereof, and a sleeve assembly utilising such a liner

Info

Publication number: WO2020239843A1
Application number: PCT/EP2020/064717
Authority: WO
Inventors: Gary Carmichael
Original assignee: Sandon Global Engraving Technology Limited
Priority date: 2019-05-28
Filing date: 2020-05-27
Publication date: 2020-12-03
Also published as: GB201907494D0

Abstract

The present invention relates to a radially compressible and elastically expansible sleeve liner with integral annular seals provided at both ends, and methods of making such a sleeve liner. The sleeve liner is typically cylindrical with annular cross-section, comprises a plurality of layers, and is adapted to be mounted within and to a relatively significantly more rigid outer sleeve, typically of metal, to c reate a sleeve assembly which is then typically used within industrial printing machinery. The liner has at least a first radially innermost a base wrap layer, a second intermediate layer of a compressible material, and a third radially outermost layer which is relatively more dimensionally stable and rigid than the compressible layer inside it but which is still nevertheless capable of expanding elastically. The liner is characterised by the provision of integral annular seals provided in both ends of the liner. The integral annular seals may be created either by providing annular channels in the liner ends, and filling, for example by forcibly injecting, the channels with a fluent adhesive composition, or by impregnating the compressible material layer at each end of the liner with a similar composition. In either case, the adhesive composition cures and sets and in doing so, automatically adheres to the respective adjacent surfaces of the respective adjacent layers surrounding the compressible layer where the adhesive composition is provided, thus automatically creating the annular seals. The adhesive composition may be elastomeric, resinous, or polymeric, but in any event, the annular seals it ultimately creates serve to effectively not only encapsulate the compressible layer within the liner but also to robustly prevent printing or coating working fluid ingress into the vulnerable compressible layer disposed behind the annular seals. In preferred embodiments, tiny air ducts of the order of 0.5mm diameter or less may be drilled through each annular seal to allow air to escape from and be drawn into the compressible layer during construction of the liner without compromising the integrity of the annular seals because relatively viscous nature of printing working fluids and their inherent large resistance to travel along capillary air ducts.

Description

A Compressible Liner. A Method of Manufacture Thereof, and A Sleeve Assembly

Utilising such a Liner

Field of the Invention

The present invention relates to a compressible liner, a method of manufacture thereof, and a sleeve assembly utilising such a liner. More specifically, the invention relates to a cylindrical liner having an annular cross-section and which is of layered construction, one of the intermediate layers within said layered construction being significantly more compressible than the or those layers disposed radially to the exterior of the compressible layer such that when the cylindrical interior surface of the liner is subjected to a radially acting compression force, for example as might be applied by pressurised air emerging from the cylindrical surface of an air mandrel, the inner diameter of the sleeve increases sufficiently to allow the liner to be slid onto and over said mandrel. Yet more specifically, the present invention relates to a compressible liner which is most commonly inserted and physically bonded inside a more substantial outer sleeve, typically of metal, to provide the completed sleeve assembly with a resilient interior which can be compressed to allow the sleeve assembly to be securely mounted on and over an arbor, spindle or other essentially cylindrical mounting component of, for example, printing, coating and metal decorating machinery.

Although the following description is provided with almost exclusive reference to sleeve assemblies (including compressible liners) commonly referred to in the printing and coating industries as Anilox sleeves or more simply Anilox/Aniloxes, persons skilled in the art should understand that the present invention is in no way specifically restricted to this particular application nor to any particular industry - the present invention merely provides a novel compressible liner construction which is ideally adapted for lining significantly more substantial sleeves to create a sleeve assembly which can easily, simply and quickly be mounted, releasably and thus removably, on and over some cylindrical supporting means.

Background to the Invention Anilox sleeve assemblies are already well known and in widespread use throughout the printing industry. Indeed, sleeve assemblies are now used almost universally within sheet- and web-fed printing and coating machinery, because they are considerably lighter than the solid cylindrical components they have largely replaced, and furthermore, sleeve assemblies are generally much quicker, easier and safer to install and remove, whether for replacement or repair. Although a detailed description of the coating and engraving techniques utilised to convert a basic sleeve assembly into an Anilox sleeve is beyond the scope of this application, a brief explanation is nevertheless provided to assist understanding of the present invention.

Anilox sleeve assemblies will generally consist primarily of a drawn or extruded Aluminium or steel outer sleeve having a wall thickness of between about 4-40mm thick depending on application and overall size, such being commonly available from manufacturers such as Blomker MetallgieBerei GmbH. The outer sleeve is by far the most substantial component of any sleeve assembly and provides the sleeve assembly with sufficient structural rigidity and strength to withstand the pressure, loads, and stresses to which the sleeve assembly will be subjected when in use. In the context of Anilox, and for other precision printing and coating sleeve assemblies generally, it is essential that the exterior surface of the outer sleeve be machined extremely precisely against a datum which substantially coincides, as far as is possible, with a central axis of the outer sleeve so that when correctly mounted on a rotating spindle, there is little or no variation in the radial dimension of the exterior surface as the sleeve rotates. In practice, it is difficult to render the exterior surface of the sleeve completely perfectly cylindrical, but dimensional variations of the order of a few (eg. 30 or less) microns are certainly achievable. Once the exterior surface of the outer sleeve has been accurately machined, it is then coated (usually by plasma spraying) with a layer of a ceramic material such as Chromium Oxide, Cr203 which can then be laser-engraved and polished, as is well known in the art.

In order that the outer sleeve can be subjected to such precision processing techniques, as the skilled reader will appreciate, there is a requirement that the outer sleeve be appropriately mounted within processing machinery and in a releasable and removable manner. Most expediently therefore, a suitably sized, annular liner structure is commonly bonded, for example using an epoxy or other thermosetting polymer adhesive composition having high thermal and chemical resistance, to the interior cylindrical surface of the outer sleeve. In order to achieve a robust bond between the liner and the outer sleeve, the liner itself is also a sleeve and is constructed, as is described in greater detail below, such that it is both radially compressible, in that its interior radial dimension can be enlarged relative to its exterior radial dimension when its interior surface is subjected to a radially expanding force, and such that the structure as a whole is capable of some slight radial elastic expansion. A liner having these qualities, and having dimensions in its pre-stressed state such that it can be slid snugly within the outer sleeve leaving only a very small annular gap (typically of the order of 1 mm or less) betwixt liner and sleeve, is mounted, for example, on an air mandrel which supplies the necessary radial expansion force to the interior surface of the liner so that it can be disposed over and slid along the mandrel. Once in position on the mandrel, the pressurised air source is removed, and the liner elastically relaxes against the cylindrical surface of the mandrel, thus being effectively securely interferingly fitted thereto. As will be appreciated by the skilled reader, in order to achieve a secure mounting, the interior radial dimension of the liner, in its pre-stressed state, is marginally less than the exterior radial dimension of the mandrel so that when the liner relaxes, the liner is in a state of radial compression. Importantly, as mentioned above, the liner is radially compressible to some degree, despite its relative thinness (typically 4- 15mm), so the residual radial compression being exerted by the mandrel only marginally enlarges the exterior radial dimension of the liner, as compared to when the liner is in its un-stressed state.

Once the liner is mounted on the air mandrel as described, a coating of a viscous liquid curable adhesive is applied to both the interior surface of the outer sleeve and the exterior surface of the liner, and the outer sleeve is then slid axially over the liner while simultaneously being rotated so that the adhesive is smeared somewhat around respective adjacent surfaces of the outer sleeve and liner, until the sleeve is correctly axially position relative to the liner. Of course, the outer sleeve can be so slid because the relative exterior and interior radial dimensions of the liner and the sleeve respectively still permit the former to fit within the latter, with the adhesive bridging the small gap between the two. Once the outer sleeve is in its desired axial position relative to the liner, the assembly is left alone to allow the adhesive to cure, typically for a period of 12-24 hours, whereafter respective surfaces of both outer sleeve and liner become securely bonded together.

When it is desired to remove the entire sleeve assembly consisting of both outer sleeve and liner can be slid the mandrel, pressurised air is again supplied to the mandrel causing the liner to be radially compressed against the relatively much more rigid outer sleeve and thus also radially displaced away from the mandrel itself. In this condition, the liner is now no longer mounted on the mandrel, and the entire sleeve assembly can be slid off the mandrel. It is the inherent radial compressibility of the liner within the outer sleeve which allows the sleeve assembly to be subsequently releasably and removably mounted within machinery whilst using compressed air.

The entire sleeve assembly is then subjected to various further machining processes. In particular, it is common to cut sleeve assemblies to length, and also to machine the end portions of both the liner within the sleeve, and the interior surfaces of the outer sleeve at either end. For example, it is always necessary to machine the ends of a sleeve assembly, both internally and externally, to provide the liner with relatively smooth annular end surfaces which lie perfectly perpendicular to the sleeve central axis, and to provide screw threads on the interior surfaces of the outer sleeve to allow for correspondingly threaded end rings to be screwed into the outer sleeve, for example as described in detail in Applicant's own prior application WO2017/089221A1. The machining of the ends of both the liner and the outer sleeve will typically involve grinding and/or milling, which will most commonly be carried out in the presence of a cooling and/or lubricating fluid, and both the machining itself and the fluids used therein give rise to several problems.

Firstly, the machining working fluid easily impregnates the liner through the annular and surfaces thereof being machined, leaving them exceedingly grubby if not completely black. Furthermore, such impregnation immediately compromises the radial compressibility characteristics of the liner, because the end regions which have been impregnated in this manner will perform differently, compression-wise, to the remaining length of the liner, particularly when the liner end regions dry out. Secondly, the grinding and milling are aggressive, abrasive processes which can easily structurally and physically damage the liner end regions, and particularly where they are adhesively bonded to the outer sleeve, rendering the assembly as a whole much more prone to working (e.g. printing and coating) fluid ingress when the sleeve assembly is in use. One of the aims of the present invention is to overcome these difficulties by largely obviating the need for directly machining the annular end surfaces of the liner itself.

Turning now to the liner, and construction and assembly thereof, the liners used in sleeve assemblies of the type described above generally comprise at least three distinct layers. The first of these is a essentially a fabric or fibrous layer which is initially, during construction of the liner, wrapped or otherwise disposed around an air mandrel or other cylindrically expandable former component, and soaked, coated, impregnated or otherwise provided with an initially liquid curable resinous composition. As may have already become apparent from the foregoing, it is critical that the liner be both inherently elastically expandable and radially compressible to some degree. Fabric and fibrous materials, in particular woven fabrics, are not only inherently absorbent but they already possess some inherent elasticity in at least one direction (e.g. circumferentially when wrapped around a mandrel). Furthermore, it is also important that the curable resinous composition which is applied to, over and/or through the fabric is one which retains some elasticity once cured, that is it does not cure to a brittle state, as some resins and adhesives do. Typically the first resin-soaked fabric layer is the thinnest of all layers of the liner, and may only be of the order of 50-400 microns, depending on the overall diameter of the liner. Alternative possible materials for this first layer include glass-fibre reinforced polyesters, fibre glass, and other essentially fibrous synthetic polymers or naturally occurring materials, and (where such are to be coated with liquid resin) which possess some inherently absorbency for liquids.

Once the first layer has been created (and where resin used, it has been cured), a compressible membrane layer is applied around the entire surface thereof. The compressible layer may simply be any open- or closed-cell foam or foam-like composition, such as, for example any polymer foam (e.g. polyurethane foam), and which is capable of adhering, or being adhered to the first layer and capable of being applied thereto at a relatively uniform thickness. In some cases, most simply, a thin (e.g. 2-6mm) sheet of foamed polymer of the desired length and width is simply wrapped around the first layer and adhered to it with suitable adhesive. To protect the exterior surface of the compressible layer, typically a masking tape having a contact adhesive on one side and a waxy liquid-repelling finish on the other is wrapped around the compressible layer so as to completely cover it. Naturally, the compressible layer must be of sufficient thickness to accommodate the required radial compression.

The liner construction is completed by the application of a further, relatively much thicker layer of a fibrous and thus absorbent material (e.g. 4-15mm). 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, and then cured. The masking tape or other protective layer provided around the compressible layer prevents the resin from contacting the compressible layer, which would, once the resin cured, seriously compromise the compressibility characteristics thereof. Once the resin has cured, the liner structure is essentially complete, the liner construction can then very easily and simply be cut into desired lengths. In some cases, the exterior cylindrical surface of the liner construction may be machined, e.g. by coarse grinding, to provide a relatively smooth and geometrically cylindrical surface of the desired dimensions, in particular the exterior diameter (ideally 300 pm less than the interior diameter of the outer sleeve within which it is to be slidingly fitted). Again, importantly, the resin used to soak the coir mat layer is one which, when cured, retains some elasticity so that the liner structure as a whole retains some degree of radial elasticity, and can thus radially expand slightly when its interior is subjected to an appropriate force.

The primary disadvantage with sleeve assemblies constructed as described above arises from the inherent absorbency of the compressible layer, and the fact that this layer is clearly exposed in the annular end surfaces of the liner. To explain further, in use, sleeve assemblies, and particularly Anilox sleeve assemblies, naturally come into contact with a variety of often chemically aggressive printing inks or lacquering or other coating fluids which can easily seep into the compressible layer of the liner at the exposed annular ends thereof within the outer sleeve. Once this happens, the compressibility characteristics of the compressible layer are immediately compromised, and in extreme cases, and particularly where the fluid therein solidifies or congeals, the liner and thus the sleeve assembly as a whole can become permanently seized to the mandrel, spindle or arbor on which it is mounted. If this occurs, then it becomes exceedingly difficult to remove the sleeve assembly without damaging or destroying it completely, and without possibly also damaging the mandrel, spindle or arbour on which it is mounted. For Anilox and other printing and coating sleeve assemblies, this is a pervasive and costly problem in the industry.

WO2017/089221A1 mentioned above describes one possible solution to this problem involving the use of screw-threaded end rings of appropriate dimensions such that when the end rings are screwed into the ends of the sleeve assembly, the axially innermost radially extending end surfaces of the end rings effectively cover the annular end surfaces of the interior liner and thus largely prevent fluid ingress into the liner through said surfaces. The solution proposed in this application has been largely successful, but not completely so.

The primary object of the present invention is therefore to provide a yet further improved solution to this problem.

A further object of the present invention is to provide a liner which has significantly improved fluid resistance characteristics, particularly at, in and around the end regions thereof, but which nevertheless retains the requisite characteristics of being both radially internally compressible to some degree and, as a structure, radially elastically expandable.

Summary of the Invention

According to a first aspect of the present invention there is provided a radially compressible and elastically expansible cylindrical liner having an annular cross-section and comprising a plurality of layers and adapted to be mounted within and to a relatively significantly more rigid outer sleeve, said liner having at least a first radially innermost a base wrap layer, a second intermediate layer of a compressible material, and a third radially outermost layer which is relatively more dimensionally stable and rigid than the compressible layer inside it but which is still nevertheless capable of expanding elastically, Characterised in that,

At both ends of the liner, the axial length of the second compressible layer is reduced as compared to the first and third layers surrounding it thereby revealing cylindrical wall portions thereof which, together with the axially inwardly disposed annular end surface of the compressible layer, define annular channels in each end of the liner, said channels having a depth which is substantially less than the overall length of the liner and in which is received an initially fluent adhesive composition which is one or more of: elastomeric, resinous, and polymeric, said adhesive composition, upon curing, becoming securely bonded to at least the said wall portions of the first and third layers thus forming effective annular seals within said channels above the otherwise exposed annular surfaces of the compressible layer behind said seals.

According to a second aspect of the present invention there is provided a radially compressible and elastically expansible cylindrical liner having an annular cross-section and comprising a plurality of layers and adapted to be mounted within and to a relatively significantly more rigid outer sleeve, said liner having at least a first radially innermost a base wrap layer, a second intermediate layer of a compressible material, and a third radially outermost layer which is relatively more dimensionally stable and rigid than the compressible layer inside it but which is still nevertheless capable of expanding elastically, Characterised in that,

At both ends of the liner, at least the second compressible layer is impregnated with an initially fluent adhesive composition which is one or more of: elastomeric, resinous, and polymeric, said impregnation occurring to a depth being substantially less than the overall length of the liner, and wherein said adhesive composition, upon curing, becomes securely bonded to such wall portions of the first and third layers as are disposed to one or other side of those regions of said compressible layer which are impregnated so as to form an effective annular seal both therewith and for the unimpregnated compressible layer behind it said impregnated regions thereof. Applicants have discovered that the requisite radially compressible, elastically expansible characteristics of liners of the present invention are not materially compromised once the initially fluent adhesive composition used to create the annular seals at both ends of the liner, provided that the sealing composition is one which hardens to an elastic, non-brittle state. Furthermore, and importantly, the use of such an initially fluent, for example liquid, composition allows at least some degree of flow or permeation of that composition, either within the annular channel or, in the case of impregnation, within the compressible layer itself, such that circumferentially, the contact achieved between the composition and those surfaces of the first and third layers of the liner lying to either side thereof will be substantially if not totally uninterrupted. Therefore, when the composition cures and hardens, it becomes effectively bonded to those surfaces of the first and third layers and in a manner which creates highly effective circumferential seals with those surfaces. This configuration effectively eliminates any possibility of fluid ingress through the interfaces between the hardened composition and the surfaces of the first and third layers to which it is bonded. Furthermore, the fact that the annular end seals are of essentially unitary construction, in that the seal itself and the manner in which it is secured between the surfaces which surround it are essentially the same, provides a far simpler and much more resilient, robust and most importantly fluid impervious construction, at least as compared to simply gluing a separate annular seal component in place. By creating annular seals in the manner provided for by the present invention, the annular seals effectively become an integral part of the liner construction itself. As the skilled reader will appreciate, such annular seals are far less likely to fail, and they (if provided at both ends of the liner) effectively completely encapsulate the compressible material layer disposed between them and between the first and third layers of the liner.

A yet further advantage of the present invention is that liners with effectively completely sealed ends can be provided having exactly the required axial length relative to the outer sleeves inside which they are be adhesively secured. Thus there is now no longer any requirement for aggressive, abrasive and possibly damaging grinding or milling processes to be carried out, at least directly on the annular ends of the liner. For instance, for an outer sleeve length of 450mm, a standard liner can be easily cut to length of, e.g. 430mm, provided with sealed ends according to the invention, and inserted completely and centrally within the outer sleeve, thus automatically leaving exposed regions of the interior surface of the outer sleeve at either end, each being of a depth of, for example, 5-20mm, without any requirement for further machining. Sleeve assemblies can thus now be manufactured easier, quicker, and more simply.

In most preferred embodiments, at least one, and most preferably both, of the pair of annular seals so created at the ends of a liner is provided with one or more air ducts which extend from the exposed annular end surface of the annular seal completely through its depth such that the compressible layer encapsulated within the liner, axially between said annular seals and radially between the liner layers lying to one or other side thereof, is in fluid communication with the ambient atmosphere and such that during assembly of a sleeve assembly, when the liner is forcibly expanded and subsequently allowed to elastically relax, air within the compressible layer can escape and be drawn through said at least one air duct.

Most preferably, the at least one air duct extends, preferably in a direction substantially parallel with the axis of the sleeve assembly, from an annular end surface of the annular seal and the compressible layer disposed behind it.

Preferably the diameter of the at least one air duct, if circular as is preferred, is less than the the radial thickness of the compressible layer. In other embodiments, the cross- sectional shape of the at least one air duct may be non-circular, for example, square, rectangular, elliptical or polygonal, but in all instances, a relevant maximum lateral dimension is preferably less than the thickness of the compressible layer. Yet further preferably, the diameter (or relevant lateral dimension) of the at least one air duct is in the range 0.2mm-1.5mm, preferably in the range 0.3mm-0.8mm, and most preferably in the range 0.3mm-0.6mm. In some preferred embodiments, a pair of air ducts is provided, most preferably being disposed in substantially diametrically opposed relation as regards the annular compressible layer and thus the annular liner generally. In a yet further preferred embodiment, the compressible layer is provided with two pairs of air ducts, each pair being preferably diametrically opposed relation, and most preferably each of the four air ducts is disposed with an angular separation of 90 degrees from any respectively angularly adjacent air duct such that each air duct is disposed at one of four possible compass-point locations within the compressible layer.

As mentioned above, the although the compressible layer of the liner is effectively completely encapsulated (radially) between the first and third layers of the liner, and (axially, at either end) by the annular seals, there remains a requirement, at least during construction of a sleeve assembly incorporating a liner of the present invention and possibly also thereafter, that air be able to escape from, and be drawn into the compressible layer, because the liner is both radially compressed and elastically expanded during the construction of any sleeve assembly as previously described. The provision of relatively tiny air ducts through the annular seals creates a fluid communication pathway between the interior, otherwise completely encapsulated compressible layer, and therefore during sleeve assembly construction, the liner can elastically react as required, and without any plastic deformation. Importantly, in the most preferred embodiments of the invention, these air ducts are dimensioned, that is their diameters (or relevant maximum lateral dimensions) are intentionally made very small such that the hydrostatic pressures that would be required to force any of the commonly used generally highly viscous liquid printing inks, lacquers, coatings etc. through the air duct opening, completely along the axial length thereof, and thence into the compressible material layer behind the annular seal are far greater than those to which printing and/or coating working fluids would ever be subjected. Thus, in practice, although the exterior opening of the air duct may become plugged with a minuscule amount of working fluid in use, this plug is axially relatively very much shorter than the total length of the air duct itself and is thus formed only in the axially outermost reaches of the duct most proximate the end surfaces of the liner. Therefore, even if the liquid of which said plug is formed subsequently congeals and/or hardens, the plug can nevertheless very easily be burst open again when a source of relatively modestly pressurised air is supplied to the outer surface of an air mandrel or other spindle or arbor assembly on which a liner according to the invention, or more likely a sleeve assembly of which such a liner forms part, is mounted. Indeed, the forces acting on any plug so formed are significantly magnified on account of the small cross-sectional area of the air duct through which air extant within the compressible layer is forced when it is being radially expanded during a dismounting operation.

Therefore, Applicants have devised a compressible liner which performs equally as well as conventional liners as regards the requisite compressibility and expansible characteristics, and yet is essentially completely sealed such that fluid ingress into the compressible layer within the liner is practically impossible.

Most preferably, the compressible layer of the liner is one of: a foam, a sponge, cellular construction, and further preferably, the compressible layer is made from one of: a naturally occurring and a chemically synthesised material. Preferably, the compressible layer consists essentially of one or more of the following common polymeric foams: Ethylene-vinyl acetate (EVA) or polyethylene-vinyl acetate (PEVA) foam, Low-density polyethylene (LDPE) foam, Nitrile rubber (NBR) foam (being any copolymers of acrylonitrile (ACN) and butadiene), Polychloroprene foam or Neoprene, Polyimide foam, Polypropylene (PP) foam, including expanded polypropylene (EPP) and polypropylene paper (PPP), Polystyrene (PS) foam, including expanded polystyrene (EPS), extruded polystyrene foam (XPS) and polystyrene paper (PSP), Styrofoam, including extruded polystyrene foam (XPS) and expanded polystyrene (EPS), Polyurethane (PU) foam, LRPu low-resilience polyurethane, Polyethylene foam, Polyvinyl chloride (PVC) foam. Preferably the material of the compressible layer possesses some inherent sorbency, in particular absorbency, or has some inherent affinity, for liquids, in particular the types of liquids (e.g. epoxy resins and the like) typically employed to bond one liner layer to another.

Preferably, the composition used to create the annular seal in or beyond the compressible layer at one or both ends of the liner is one of: a reactive or non-reactive adhesive composition. Further preferably, the adhesive composition is one of: a drying, contact or hot melt adhesive, and is one of: a one-part composition, and a two-part composition. In most preferred embodiments, the adhesive composition comprises two parts which ultimately cure into a hardened state possessing at least some residual elasticity. Most preferably, the adhesive composition is selected from the following group of two-part adhesive mixtures: a polyester resin & a polyurethane resin, a polyol & and a polyurethane resin, and an acrylic polymer and a polyurethane resin. In some preferred embodiments, the adhesive composition may be forcibly cured or set, for example by the application of one or more of: heat, light, pressure, ultrasound.

Preferably, the axial depth of the annular seal, howsoever provided, measured from the annular end surface in which said annular seal is provided, is most preferably at least one order of magnitude less than the length of the liner, more preferably between 1 and 4 orders of magnitude less than the length of the liner. In most practical applications, for example convention Anilox and metal decorating sleeve assemblies, the overall axial lengths of the sleeve assemblies may range from 150mm to 1500mm, and the depth of the annular seals created in the liners within such sleeve assemblies may range from 0.8-20mm. For the traditionally relatively short metal decorating sleeves (often no more than 450mm long), a most common range of the depth of the annular seals in the interior liners may be in the range 1 -5mm.

In additionally preferred embodiments of the invention, the innermost layer of liner is additionally rebated at both ends of the liner, said rebate having a radial dimension which is less than the thickness of said layer and having an axial dimension which is substantially equal to, and more preferably marginally (e.g. 0.1 -2mm) greater than the axial length (i.e. the depth) of the annular seal adjacent and to the inside of which said rebate is provided.

The abovementioned rebate may be provided in different ways but may most commonly be created by grinding or otherwise machining out the interior end regions of the liner with high precision after the liner construction is otherwise complete. In its completed state, as the skilled person will readily understand, the liner is not only a rigid, manageable body, but also the adhesive or epoxy resin with which the base wrap layer is impregnated has fully cured and set to a state in which it can be readily ground or machined. Furthermore, as previously mentioned, the base wrap layer of the liner constructions is already a relatively thin layer, and although still fabric and/or fibrous in nature, once the epoxy or other resin has cured and set within the base wrap layer, this layer as a whole acts much more like a machinable solid than do the other, relatively much thicker layers of the liner.

In a third aspect of the present invention there is provided a method of manufacturing a liner which is both radially compressible and elastically expansible comprising the steps of:

Disposing a first layer of a base wrap material having around a cylindrical former component, said base wrap material being essentially fibrous and comprising, either separately or inherently, a curable composition,

Curing said curable composition in place around the cylindrical former so as to provide a hardened but radially elastically expansible base wrap layer,

Adhering a second layer of a compressible material of substantially uniform thickness around the exterior of the cylindrical surface of the cured base wrap layer, Applying a coating or layer of a fluid-impregnable composition or material to the exterior cylindrical surface of the compressible layer to render it substantially impervious to ingress of liquid through said exterior cylindrical surface,

Applying a third coating or layer of an absorbent material to the exterior cylindrical surface of the fluid-impregnable coating or layer,

Substantially completely impregnating said third coating or layer with a resinous curable composition, and curing said composition so as to provide the liner with an essentially hard exterior shell which is nevertheless capable of being radially elastically expanded,

The method being characterised in that

At both ends of the liner, the annular end surface of the compressible layer is rebated by a predetermined distance from the annular end surfaces of at least the first and third layers such that annular channels are defined in those ends by said compressible layer annular end surface and respective exposed side wall portions of said first and third layers,

And the method includes the further steps of

Filling said annular channels with an initially fluent curable adhesive composition which is one or more of: elastomeric, resinous, polymeric, such that it the annular end surface of the compressible layer is completely covered thereby and the respective exposed wall portions of the adjacent first and third layers are substantially covered thereby,

Curing said adhesive composition thereby creating annular seals at both ends of said liner.

In preferred embodiments, the method includes the further step of:

Creating at least one air duct through at least one of: said cured adhesive composition, and an annular end surface of said third layer, said air duct having an axial length at least equal to the axial depth of the annular seal and opening into said compressible layer disposed behind said annular seal so as to create a fluid communication pathway between the compressible material and the ambient atmosphere.

In one preferred embodiment, the at least one rebated annular channel is formed by providing a second layer of compressible material of reduced axial length relative to the first and third layers lying to the inside and outside thereof such that the annular end surface of said compressible layer is set back from the respective annular end surfaces of the first and third layers. In an alternatively preferred embodiment, the at least one rebated annular channel is formed by arranging the second layer of compressible material such that, at at least one end of the liner, the annular end surface thereof lies flush with respective annular end surfaces of the first and third layers, and then removing an annular section of the compressible layer, for example by routing, drilling, milling, or reaming, to a predetermined depth such that the resulting annular end surface of the compressible layer is set back from the respective adjacent annular end surfaces of the first and third layers lying on one or other side thereof.

In a fourth aspect of the present invention there is provided a method of manufacturing a liner which is both radially compressible and elastically expansible comprising the steps of:

Disposing a first layer of a base wrap material having around a cylindrical former component, said base wrap material being essentially fibrous and comprising, either separately or inherently, a curable composition, Curing said curable composition in place around the cylindrical former so as to provide a hardened but radially elastically expansible base wrap layer,

And the method being characterised by the further steps of

At both ends of the liner, impregnating annular regions substantially coincident with the annular end surfaces of the compressible layer with an initially fluent curable adhesive composition such that said said composition is absorbed into said compressible layer to a predetermined depth and substantially throughout its thickness whereby said adhesive sealing composition comes into contact with both respective wall portions of the first layer lying to the inside of the compressible layer, and with respective wall portions of the fluid impregnable layer or coating disposed to the outside thereof,

Curing said adhesive sealing composition thereby creating annular seals in both ends of the liner.

In most preferred embodiments, the method includes the further step of

Creating at least one air duct through at least one of: said cured adhesive composition, and an annular end surface of said third coating or layer, said air duct having an axial length at least equal to the axial depth of the annular seal and opening into said compressible layer disposed immediately behind said annular seal so as to create a fluid communication pathway between the compressible material and the ambient atmosphere.

Preferably the compressible layer is impregnated to a depth in the range 1 -20mm, and more preferably 1 -5mm.

Preferably, the at least one air duct is created by drilling, and most preferably the diameter of the drill hole is in the range 0.2mm-1.5mm, preferably in the range 0.3mm-0.8mm, and most preferably in the range 0.3mm-0.6mm. In most preferred embodiments, the air duct or ducts are provided exclusively within and through the annular seals and the lateral dimension of the drill hole is less than the radial thickness of said annular seals, howsoever provided.

Preferably, at least two air ducts are created in each end of the liner, in and through the cured adhesive sealing composition through to the compressible material layer therebehind, and preferably said at least two air ducts are arranged in diametrically opposed relation. Further preferably, at least two pairs of air ducts are created in and through the cured adhesive sealing composition through to the compressible material layer therebehind, each air duct in any pair being arranged in diametrically opposed relation, and most preferably each air duct is angularly disposed relative to any adjacent air duct by 90 degrees so that each air duct is disposed at one of four possible compass- point locations.

Preferably, the thickness of the third layer is a multiple of the combined thicknesses of the first and second (compressible) layers, said multiple being in the range 1 -10.

In particularly preferred embodiments, the method(s) include the further step, either prior to or after the creation of the one or more air ducts through the annular seals, of physically disrupting one or both of the annular end surfaces of the liner, for example by annealing, swaging, grinding, or cutting (e.g. using a band saw), to such an extent or at such a location that all of the annular end surfaces of the first and third, and optionally the fluid impregnable, layers and the intervening annular seal are subjected simultaneously to the physically disruptive treatment. This particular step is advantageous because it has the effect of somewhat melding the annular seal with the third layer and/or the fluid impregnable lying to the exterior thereof to the extent that the two become largely or completely indistinct, visibly, physically and structurally. This is especially true if the curable composition with which the exterior third layer is impregnated or soaked prior to being cured is the same as that employed to create the annular seal (as is the case in most preferred embodiments). In this case, not only is the boundary between any respective adjacent layer completely obscured, but it can be understood that the respective layers may actually become, at least to some extent, integrated with one another, that is one forms part of the other and vice versa. It is believed that this physical disruption, at least at and immediately adjacent the exposed interface between the composition of which the annular seal is comprised and that present in the third layer, yet further improves the seal in that region because any imperfections there might have otherwise been in the seal are effectively filled in or otherwise cured by virtue of the physical disruption treatment.

In one particularly preferred embodiment, a liner according to the present invention and adapted for use as the interior of an Anilox or metal decorating sleeve assembly, has an overall exterior diameter in the range 50-700mm, an interior diameter in the range 40-650, a first base wrap layer having a thickness in the range 0.8-2mm, a second compressible material layer having a thickness in the range 2-4mm, (where applicable) a fluid impregnable coating or layer having a thickness in the range of 0.5-2mm, and a third layer (known commonly as a composite or build-up or bulking layer) having a thickness in the range 4-15mm, these ranges being of course dependent on one another and preferably substantially in proportion with one another.

In other aspects, the present invention also provides a liner made according to the method described above, and a sleeve assembly incorporating a liner, either manufactured according to the method above or as prescribed in earlier aspects of the present invention.

For the avoidance of doubt, preferred features of the first and second aspects of the present invention may be applicable to, and thus be preferred features of, other subsequent aspects of the invention, and vice versa, as will be immediately apparent from the foregoing and the following specific description, and as will be understood by the skilled reader. It is merely for brevity that such features are not repeated.

A specific embodiment of the invention is now described by way of example and with reference to the accompanying drawings wherein.

Brief Description of the Drawings

Figure 1 shows an exploded perspective view of one end of a sleeve assembly of prior art construction, together with an end ring adapted for screw fit into said end,

Figure 2 shows a partial schematic perspective view of one end of a liner according to one embodiment of the present invention in an initial stage of construction,

Figure 3 shows a partial sectional view of the liner of Figure 2 through Il l-Ill, and at a further stage of construction,

Figure 4 shows a partial sectional view of the liner of Figure 2 after its construction is largely complete,

Figure 4A shows an enlarged schematic view of one side of one end of the liner of Figure 4 when distended as a result of an outwardly acting compressive force applied to the interior cylindrical surface of the innermost layer of the liner,

Figures 4B, 4C, 4D show respectively partial sectional, and first and second enlarged sectional views of a modified embodiment of the liner of Figures 1 -4 and 4A, and

Figure 5 shows a partial schematic sectional view of one end of a liner constructed according to an alternative aspect of the invention. Detailed Description

Referring firstly to FIG. 1 , there is shown a perspective view of a sleeve assembly 2 and corresponding end ring 4 of prior art construction, in particular as described in Applicant's own prior application abovementioned. In the context of the present invention, only the sleeve assembly 2 is relevant, and in particular the liner fixedly bonded to the interior thereof. In the Figure, an open end 6 of the sleeve assembly is illustrated prior to screw fitting insertion of the end ring 4 therein. Sleeve 2 is of generally tubular construction, and in practically all circumstances, the sleeve will be geometrically cylindrical. The primary structural component of the sleeve assembly itself is an annular aluminium or steel tube 8 (which in FIG. 1 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, at least for Anilox and general printing sleeve assemblies). The open end 6 of the tube 8 is internally rebated which: enlarges the internal diameter of the tube in the end region,

reduces the wall thickness of the tube in the end region, and

defines an internal shoulder 14 at some short (typically of the order of 5-25 mm) distance axially inside the tube remote from the open end 6.

After internal rebating, an axial inner surface 16 is defined inside the tube 8 and screw thread formations 18 are ideally provided in the axially innermost region of said axial inner surface 16 to allow the end ring, provided with corresponding screw threads, to be screwed into the open end of the sleeve assembly and exceedingly firmly secured therein.

In terms of the interior of the tube 8, as is common for sleeve assemblies with which the present invention is concerned, a liner assembly 30, 32, 34 is inserted into and ultimately securely bonded as previously described to the innermost axial cylindrical surface of the tube. This liner allows the sleeve assembly to be internally expandable to at least some degree as required if the sleeve assembly is to be capable of being mounted on and over, for example, an air mandrel, in a repeatable and removable fashion. In the embodiment illustrated, the liner consists of a first, radially innermost layer 30, being a base wrap layer, and is commonly of a fibreglass-type material, or in some cases, a glass (or other) fibre reinforced plastics or polymer material. In some instances, the base wrap layer may be comprised, or consists essentially, of a fabric material which is coated, soaked, or otherwise impregnated with an initially liquid but curable resinous substance, such as an epoxy resin which can be cured hard, for example by baking in an oven. In any event, base wrap layer is essentially relatively much thinner than the other layers of the liner, as can be seen in the figure, and typically the base wrap layer may only be of the order of 0.5-2.5mm thick. To the radially cylindrical exterior surface of layer 30 is provided a second layer 32 of a compressible material such as a polyurethane foam, and to the radially exterior surface thereof is provided a third layer 34, commonly known as a composite build-up layer which is typically formed of a coir mat or similarly highly absorbent bulking material which can be soaked with an epoxy resin which is again cured hard to provide the liner with a hard, but nevertheless elastically deformable outer shell. As can be seen in the Figure, the radially exterior-most cylindrical surface of third layer 34 interfaces with the innermost axial surface of the tube 8, and will in most cases be securely bonded thereto using a high strength industrial adhesive. As can be seen in the Figure, each of layers 30, 32, 34 have annular end surfaces which lie flush with one another and together constitute the annular end surface of the liner as a whole. Finally, as previously mentioned, in order to render the exterior surface of the compressible layer 32 impervious to, or at least protected from, the resinous curable substance in which layer 34 is soaked during liner manufacture, it is common to apply a very thin layer or coating (not shown) of a masking tape or similar material to the exterior cylindrical surface of layer 32 prior to application of layer 34.

Importantly, in the context of the present invention, the compressible second layer 32 is shown as being completely exposed and although the end ring 4, once fully and completely screwed into the open end of the sleeve assembly, may come into abutting contact with the annular end surface of the liner and thus compressible layer 32 thereof, said compressible layer is nevertheless otherwise completely exposed and thus exceedingly vulnerable to fluid ingress. This problem is further exacerbated as the compressible layer is, by its compressible nature, absorbent and therefore and printing or coating fluid that does come into contact therewith will be quickly absorbed thereby, with detrimental consequences. The most common path for such fluid ingress will be through the seam (or, if poorly manufactured, the gap) formed between the end surface of the end ring and the annular end surface of the liner adjacent thereto, and this is known to occur frequently, even although the liner is interferingly secured to an air mandrel, spindle, or arbor, because the interior diameter of the end ring must always by marginally larger than the exterior radial dimension of the mandrel, spindle or arbor if the sleeve assembly as a whole is to be capable of being slid on to and thereover. A yet further problem not previously described is that when a supply of pressurised air is connected to, for example, the air mandrel, on which the sleeve assembly of figure 1 is mounted, the annular end surface of (at least) compressible layer 32 will inevitably move relative to the stationary adjacent end surface of the end ring. This can have the effect of not only wiping extant fluid onto and over the end surface of the end ring thus increasing the possibility that such fluid will come into contact with the otherwise exposed annular end surface of the compressible layer 34, particularly as it is allowed to elastically relax once the pressurised air source is removed or when the sleeve assembly is removed, but also, if this is performed repeatedly (as will often be the case because sleeve assemblies are often removed, replaced, and re-installed), then the annular end surface of the liner could experience wear issues, thus further increasing the likelihood of fluid ingress through the seam betwixt end ring and liner annular end surface.

The present invention provides a solution to the problems discussed immediately above, and those earlier mentioned, and referring now to Figure 2, there is shown a liner indicated generally at 40 at a relatively preliminary stage of construction in which respective first base wrap, second compressible, and third composite build-up layers 42, 44, 46 respectively have been formed, and bonded to one another, for example as might be achieved using prior art techniques already discussed. Indeed, liner 40 is largely identical to liner 30, 32, 34 of Figure 1 except for the fact that layer 44 has been drilled routed, reamed or milled out to a predetermined depth, for example of the order of 1 -20mm such that the otherwise annular end surface of the liner is provided with a continuous annular channel therein as can be more clearly seen in Figure 3. In this latter Figure, various layers 42, 44, 46 are shown, and the annular channel 48 is clearly visible and defined between respective exposed wall portions 42A, 46A of layers 42, 46, and the base of said annular channel 48 is provided by the rebated annular end surface 44A of compressible layer 44. Also in Figure 3, said annular channel 48 is shown part-filled with an initially fluent or liquid curable adhesive sealing composition 50 which may be simply poured into the annular channel 48 (as shown), forcibly injected thereinto, or otherwise deposited therein. Also visible in Figure 3 (but not visible or referenced in Figure 2) is a fluid impervious and/or protective coating or layer 49 applied to the entirety of exterior cylindrical surface of layer 44 during assembly of the liner and which prevents any epoxy or other resinous substance with which layer 46 is ultimately soaked or impregnated with as part of the liner construction from seeping into layer 44.

In accordance with this particular embodiment of the invention, fluent sealing adhesive composition 50 is progressively poured or otherwise deposited into annular channel 48 until the latter becomes filled therewith, as illustrated in Figure 4, and the upper surface of the composition lies generally flush with the upper annular end surfaces of adjacent layers 42, 46. Importantly, it is to be noted that the composition 50 is in complete wetting contact with not only respective wall portions 42A, 46A of layers 42, 46, but also in similarly complete wetting contact with rebated annular end surface of compressible layer 44. In most cases, the base wrap layer 42 is so thin that it is partially translucent so, as illustrated at 51 , the composition 50 within the annular channel can be seen through the said layer 42. Thus, once the adhesive sealing composition sets, hardens or cures, by whatever physical or chemical process may be required to achieve this, the composition is firmly and completely bonded to all these surfaces in a manner which creates a highly effective seal not only (most importantly) for the rebated annular end surface 44A, but also against and with surfaces 42A, 46A. The existence of these latter seals effectively completely preclude ingress of liquid along the sealingly bonded interfaces between composition 50 and surfaces 42A, 46A. Furthermore, the adhesive sealing composition hardens to a solid which is at once completely bonded to all respective surfaces 42A, 44A, 46A and which is nevertheless still capable of elastic deformation, for example when the interior cylindrical surface of base wrap layer 42 is subjected to a source of pressurised air. When base wrap layer is being radially outwardly elastically deformed in this manner, importantly not only does the hardened composition 50 react sufficiently elastically, for example by slightly bulging outwardly over its free surface, but the bonds between the composition and the respective surfaces 42A, 44A, 46A also react elastically such that their integrity is not compromised, and the seals formed at these surfaces remain fundamentally intact. An example of such a distended configuration described is depicted in Figure 4A.

As required by the present invention, and as is schematically illustrated in Figure 4, in order that air otherwise trapped within compressible layer 46 can escape when the interior cylindrical surface of the base wrap layer 42 is subjected to a force tending to outwardly expand it, one or more small diameter (e.g. 0.3-1.5mm) air ducts 52 are provided, for example by drilling as indicated generally at 54, both entirely within and completely axially through hardened composition 50. Air ducts 50 may optionally extend further directly into the compressible layer 46 itself, as indicated in the figure, but this is optional. The primary requirement is that the air ducts 50 extend, most preferably but not mandatorily axially through the hardened adhesive sealing composition 50 such that fluid, i.e. air, otherwise completely trapped (if both ends of the liner are treated as described above) within the compressible layer 54 has some means of escaping, and likewise when the compressible layer is elastically expanding back from a radially compressed state to a relatively uncompressed state, ambient air can be drawn through the air ducts and the compressible layer is thus not maintained in a state of relative compression as would be the case if the air duct functioned only as a one-way valve.

As previously mentioned, the present invention is particularly advantaged in that the diameter of the preferably drilled air duct(s) is such that they are essentially completely impenetrable by the typically viscous printing inks, coatings and lacquers commonly used in modern printing and coating machinery. In particular, providing that the air duct(s) have a diameter of, for example less than 1.5mm, preferably less than 1 mm, viscous fluid and surface tension effects present an entirely sufficient barrier to entry of such fluids into the air duct, let alone along any part of the axial length thereof. Thus, in practice, what tends to occur is that such viscous fluids simply form a shallow plug over the the uppermost otherwise open end of the air duct, which in itself provides a sealing and protective function as regards the compressible layer at the other end of the air duct. Even if the viscous liquid which forms said plug subsequently congeals and/or hardens, the hydrostatic pressure exerted thereon by air being forced through the air duct as air is forced from the compressible layer as it becomes increasingly compressed is so great that the plug is si m [ply either burst open or blown away from the end of the air duct, and the fluid communication between compressible layer and ambient atmosphere is restored. Naturally, once this has occurred, the compressible layer can of course again elastically relax, because any plug seal which had formed has already been destroyed as the compressible layer is forcibly compressed.

Referring now to Figures 4B, 4C, in which reference numerals are used to reference identical parts of the liner illustrated in Figures 2, 3, 4, 4A, it can be seen that the innermost base wrap layer 42 may be rebated, for example by being ground or machined from the inside of the liner by a small amount, typically only of the order of 0.1 -0.6mm radially, such that (as can be more readily seen in Figure 4C) a small shoulder 42A of that radial dimension is created inside the liner, strictly only in the base wrap layer, at an axial depth which is at least as deep as the annular channels 48 (see Figure 3) which receive the adhesive sealing composition 50 which ultimately forms the annular seal. In preferred arrangements, the said shoulder may even be disposed slightly deeper than this, e.g. 0.1 -0.5mm deeper. Such grinding or machining is made possible by the fact that the base wrap layer is both relatively thin and constituted predominantly of a cured epoxy resin which is impregnated entirely throughout a relatively thin supporting fabric substrate. As such therefore, it can be machined with relative ease as compared to the much radially thick other layers, which would be prone to bursting and disintegrating if they were subjected to any quickly rotating machine tool.

It is to be mentioned here that this rebating, if provided, is performed at both ands of the liner. Furthermore, said rebating may be performed on the base wrap layer in any and all embodiments of the present invention, and in particular where annular channels described above are not provided and instead the compressible layer is impregnated with adhesive composition to a predetermined depth as later described, then, as the skilled reader should immediately understand, the rebating should be conducting at at least the depth of impregnation, or preferably slightly deeper than the depth of impregnation.

In certain instances, for example where the adhesive composition 50 sets or is cured into a hard solid mass which is relatively less elastically resilient than the surrounding build up layer 46 (and, of course, the compressible layer 44 itself, as will inevitably be the case), it can be necessary to provide rebates as described to allow for a slightly different mechanism of radial expansion of the liner, in particular in the region of its ends. For example, if the adhesive composition when set is less inclined to expand and flex than other component parts of the liner, then when a radially expanding force, such as indicated by arrows 43 in Figure 4C, is applied to the interior surface of the base wrap layer in the completed liner, the end regions thereof will be more resistant to radially outward expansion on account of the solidity of the adhesive composition behind them, and thus operators could experience difficulties in removing the sleeve on account of it being more difficult to expand the end regions of the innermost base wrap layer of the liner away from whatever mandrel, arbor, or other component (not specifically illustrated) the sleeve assembly may be mounted on at the time. Thus to overcome these specific end-effect problems, radially small rebates as described may be provided at both ends of the liner so that the end regions of the base wrap layer are actually spaced apart from and lie clear of the exterior most surface of the component on which the sleeve assembly is mounted, leaving a radially tiny annular air gap between the base wrap layer end region and said component. Then, when the time comes to remove the sleeve assembly, and pressurised air is supplied to the interior of the liner as indicated by arrows 43, such force acts only that portion of the base wrap which is adjacent the compressible layer, and not the annular seals. In this case not only is the compressible layer still successfully radially compressed and thus the component-contacting base wrap layer, which is relatively elastic and capable of elastic deformation, is radially displaced away from the component on which it is mounted. Furthermore, as can be seen yet more clearly in Fig.4D, the elastic nature of the base wrap layer allows for some slight inward elastic bending and elastic extension of that portion thereof which remains above the shoulder 42A, as shown at 43A. Such bending is so slight that the rebated tip of the base wrap layer never interferes with the component over which it is mounted, but nevertheless allows for the remaining majority of the base wrap layer to be radially displaced away from the cylindrical component to a sufficient degree (often only of the order of a few hundreds of micrometers, pm) to allow the sleeve assembly as a whole to be removed therefrom. Referring finally to Figure 5, there is shown a schematic sectional elevation of one end of a liner 60 constructed according to a different aspect of the present invention. In particular, a conventional liner, such as described with reference to Figure 1 above, and having first base wrap, second compressible, and third composite build up layers 62, 64, 66 respectively, and having a further protective fluid impregnable coating or layer 69 applied to the exterior cylindrical surface of compressible layer 64 so as to completely cover that surface of that layer, is treated with an adhesive sealing curable composition. Specifically, the exposed end annular end surface of layer 64, which in this instance lies flush with annular end surfaces of adjacent layers 62, 69, 66, is impregnated with the adhesive sealing curable composition to a predetermined depth, for example 1 -20mm. Again, the extent and depth to which said composition has impregnated the compressible layer 64 may be seen through the relatively much thinner and partially translucent innermost base wrap layer 62, as indicated at 71. Such impregnation is possible of course because of the inherent absorbency of the compressible layer, which will typically be a polymer foam comprising multiple cell-like voids in its structure which are capable of being occupied by and retaining liquids. Although not specifically referenced in Figure 5, the initially liquid composition is allowed to set, harden or cure in place within the end region of the compressible layer 64 having been impregnated therewith, and in doing so, said composition becomes sealingly bonded to respective wall portions of the adjacent layers of the liner, in this case protective and fluid-impregnable layer 69 disposed around the exterior cylindrical surface of compressible layer 64, and the base wrap layer 62 lying to the inside of said compressible layer. Once again, after the composition has set, cured or hardened, not only is an effective seal is created between the layers lying to the inside and outside of the impregnated end region of the compressible layer, but the hardening, curing or setting of the composition within that end region of the compressible layer causes a fundamental change to the physical and chemical characteristics of the compressible layer in that end region to the extent that an effective seal is created at that end region above the un-impregnated material of the compressible layer lying beneath the seal so created. Once the composition has cured, set or hardened in this manner, one or more air ducts (not shown in Figure 5, but of broadly identical configuration and formed in broadly identical manner to those illustrated in Figure 4) is again drilled completely axially though the end region of the compressible layer having been impregnated and into the material of the compressible layer which has not been so impregnated. In this manner, the unimpregnated material of the compressible material lying beneath and behind the seal so formed therein can be allowed, in effect, to breathe when being compressed and when elastically relaxing from a compressed state.

In abstract form, therefore, the invention may be summarised thus: The present invention relates to a radially compressible and elastically expansible sleeve liner with integral annular seals provided at both ends, and methods of making such a sleeve liner. The sleeve liner is typically cylindrical with annular cross-section, comprises a plurality of layers, and is adapted to be mounted within and to a relatively significantly more rigid outer sleeve, typically of metal, to create a sleeve assembly which is then typically used within industrial printing machinery. The liner has at least a first radially innermost a base wrap layer, a second intermediate layer of a compressible material, and a third radially outermost layer which is relatively more dimensionally stable and rigid than the compressible layer inside it but which is still nevertheless capable of expanding elastically. The liner is characterised by the provision of integral annular seals provided in both ends of the liner. The integral annular seals may be created either by providing annular channels in the liner ends, and filling, for example by forcibly injecting, the channels with a fluent adhesive composition, or by impregnating the compressible material layer at each end of the liner with a similar composition. In either case, the adhesive composition cures and sets and in doing so, automatically adheres to the respective adjacent surfaces of the respective adjacent layers surrounding the compressible layer where the adhesive composition is provided, thus automatically creating the annular seals. The adhesive composition may be elastomeric, resinous, or polymeric, but in any event, the annular seals it ultimately creates serve to effectively not only encapsulate the compressible layer within the liner but also to robustly prevent printing or coating working fluid ingress into the vulnerable compressible layer disposed behind the annular seals. In preferred embodiments, tiny air ducts of the order of 0.5mm diameter or less may be drilled through each annular seal to allow air to escape from and be drawn into the compressible layer during construction of the liner without compromising the integrity of the annular seals because relatively viscous nature of printing working fluids and their inherent large resistance to travel along capillary air ducts.

Claims

CLAI MS

1. A radially compressible and elastically expansible cylindrical liner having an annular cross-section and comprising a plurality of layers and adapted to be mounted within and to a relatively significantly more rigid outer sleeve, said liner having at least a first radially innermost a base wrap layer, a second intermediate layer of a compressible material, and a third radially outermost layer which is relatively more dimensionally stable and rigid than the compressible layer inside it but which is still nevertheless capable of expanding elastically,

Characterised in that,

2. A radially compressible and elastically expansible cylindrical liner having an annular cross-section and comprising a plurality of layers and adapted to be mounted within and to a relatively significantly more rigid outer sleeve, said liner having at least a first radially innermost a base wrap layer, a second intermediate layer of a compressible material, and a third radially outermost layer which is relatively more dimensionally stable and rigid than the compressible layer inside it but which is still nevertheless capable of expanding elastically,

Characterised in that,

At both ends of the liner, at least the second compressible layer is impregnated with an initially fluent adhesive composition which is one or more of: elastomeric, resinous, and polymeric, said impregnation occurring to a depth being substantially less than the overall length of the liner, and wherein said adhesive composition, upon curing, becomes securely bonded to such wall portions of the first and third layers as are disposed to one or other side of those regions of said compressible layer which are impregnated so as to form an effective annular seal both therewith and for the unimpregnated compressible layer behind it said impregnated regions thereof.

3. A liner according to either of claims 1 or 2 wherein at least one of the pair of annular seals created at the ends of a liner is provided with at least one air duct having an axial length being at least equal to the axial depth of the adjacently disposed annular seal, said air duct extending from the exposed annular end surface of the liner and opening into the compressible layer of the liner disposed immediately behind said annular seal, such that the compressible layer encapsulated within the liner, axially between said annular seals and radially between the liner layers lying to one or other side thereof, is in fluid communication with the ambient atmosphere.

4. A liner according to claim 3 wherein the at least one air duct extends in a direction substantially parallel with the axis of the sleeve assembly and is disposed within and extends exclusively through an annular seal.

5. A liner according to claim 4 wherein the at least one air duct is circular in cross- section and has a diameter which is less than the radial thickness of the compressible layer.

6. A liner according to claim 5 wherein the diameter of the at least one air duct is in the range 0.3mm-0.6mm.

7. A liner according to any of claims 3-7 wherein a pair of air ducts is provided at each end of the liner, each of said air ducts being disposed in substantially diametrically opposed relation as regards the annular seals provided in said liner.

8. A liner according to any of claims 3-7 wherein two pairs of air ducts is provided at each end of the liner, each pair being preferably diametrically opposed relation and each of the four air ducts is disposed with an angular separation of 90 degrees from any respectively angularly adjacent air duct such that each air duct is disposed at one of four possible compass-point locations around the end of the liner.

9. A liner according to any preceding claim wherein the compressible layer consists essentially of one or some combination of more of the following synthetic polymeric foams: Ethylene-vinyl acetate (EVA) or polyethylene-vinyl acetate (PEVA) foam, Low- density polyethylene (LDPE) foam, Nitrile rubber (NBR) foam, Polychloroprene foam, Neoprene, Polyimide foam, Polypropylene (PP) foam, including expanded polypropylene (EPP) and polypropylene paper (PPP), Polystyrene (PS) foam, expanded polystyrene (EPS) foam, extruded polystyrene foam (XPS), polystyrene paper (PSP) foam, Styrofoam, Polyurethane (PU) foam, low-resilience polyurethane (LRPu), Polyethylene foam, Polyvinyl chloride (PVC) foam.

10. A liner according to any preceding claim wherein the adhesive composition used to create the annular seal in or beyond the compressible layer at both ends of the liner is one of:

Reactive, non-reactive, drying, contact, hot melt, one-part, two-part.

1 1. A liner according to claim 10 wherein the adhesive composition comprises two parts which ultimately cure into a hardened state possessing at least some residual elasticity, the two parts of said adhesive composition being selected from the group consisting of: a polyester resin & a polyurethane resin,

a polyol & and a polyurethane resin,

an acrylic polymer and a polyurethane resin.

12. A liner according to any preceding claim wherein the axial depth of the annular seals, measured from the annular end surface in which an annular seal is provided, is between 1 and 4 orders of magnitude less than the overall length of the liner.

13. A liner according to any preceding claim wherein the axial depth of the annular seals provided therein lies in one of the following ranges: 0.8-20mm, 1 -5mm.

14. A liner according to any preceding claim wherein the innermost layer of liner is rebated at both ends, said rebates having a radial dimension which is less than the thickness of said layer and having an axial dimension which is one of:

substantially equal to, and marginally greater than,

the axial length of the annular seals adjacent and to the inside of which said rebates are provided and disposed.

15. A sleeve assembly incorporated the liner of any of claims 1 -14.

16. A method of manufacturing a liner which is both radially compressible and elastically expansible comprising the steps of:

The method being characterised in that

At both ends of the liner, the uppermost annular end surface of the compressible layer is rebated by a predetermined distance from the annular end surfaces of at least the first and third layers such that annular channels are defined in those ends by said compressible layer annular end surface and respective exposed side wall portions of said first and third layers,

The method including the further steps of

Filling said annular channels with an initially fluent adhesive composition which is one or more of: elastomeric, resinous, polymeric, such that it the annular end surface of the compressible layer is completely covered thereby and the respective exposed wall portions of the adjacent first and third layers are substantially covered thereby,

17. A method of manufacturing a liner which is both radially compressible and elastically expansible comprising the steps of:

the method being characterised by the further steps of

At both ends of the liner, impregnating annular regions substantially coincident with the annular end surfaces of the compressible layer with an initially fluent curable adhesive composition such that said composition is absorbed into said compressible layer to a predetermined depth and substantially throughout its radial thickness whereby said adhesive sealing composition comes into contact with both respective wall portions of the first layer lying to the inside of the compressible layer, and with respective wall portions of the fluid impregnable layer or coating disposed to the outside thereof,

18. A method according to either claim 16 or 17 including the further step of:

Creating at least one air duct through at least one of: said cured adhesive composition, and an annular end surface of said third layer, said air duct having an axial length at least equal to the axial depth of the annular seal created by said cured adhesive composition and opening into said compressible layer of the liner disposed behind said annular seal so as to create a fluid communication pathway between the compressible material of said compressible layer and the ambient atmosphere.

19. A method according to claim 16 and any claim dependent thereon wherein the rebated annular channels are formed by providing a second layer of compressible material of reduced axial length relative to the first and third layers lying to the inside and outside thereof such that the annular end surfaces of said compressible layer are set back from the respective annular end surfaces of the first and third layers.

20. A method according to any of claims 16-19 including the further subsequent step of physically disrupting one or both of the annular end surfaces of the liner to such an extent or at such a location that all of the annular end surfaces of the first and third, and optionally the fluid impregnable, layers and the intervening annular seal are subjected simultaneously to the physically disruptive treatment.