CA1066469A - Covering method and assembly - Google Patents

Abstract

A B S T R A C T
In a method and assembly for covering a substrate, an insert and, in operation, the substrate are positioned in the direction of recovery of a heat-recoverable member.
The insert comprises a material that is fusible or a material that becomes less viscous on heating, and may be corrugated or may include at least one protuberance, which may comprise a material that can become flowable or an in-fusible material. Corrugations or protuberances are such that they can be detected through the heat-recoverable member before application of an amount of heat which is sufficient to cause the said material to flow, but can in-dicate, for example by fusing so that they are no longer detectable, when sufficient heat has been applied to cause the said material, and/or the corrugations or protuberances, to flow.

Description

It has long been known that recoverable articles are uaeful for covering, protecting and/or encapsulating other articles. For example, elastomer sleeves have often been used to cover cylindrical articles merely by choosing a sleeve which, in its relaxed cDndition, has a diameter less than that of the article to be covered. The tendency of the sleeve to retract when it has been expanded and placed over the article results in a covering for the article which, for some few purposes, is satisfactory. Heat-recoverable articles have been used in a somewhat similar manner and generally found superior to elastomer covers in many applications. However, many of the previously proposed heat-recoverable encapsulating articles have not been com-pletely satisfactory, particularly under circum~tances where a strong and impervious bond between the recoverable article and the workpiece which i8 to be covered is desired. For example, it iB common practice to install insulating coverings over electrical components such as conductors. The insulat-ing material must, of course, be securely bonded to the con-ductor in order to protect the conductor from water or air or other media with which it may come into contact. Furthermore, it is also highly important that there be no air spaces between the covering and the conductor. The occurrence of air spaces is particularly troublesome where the insulating material is applied to a substrate having an irregular surface, for example a plurality of wires which have been twistea together to form a cable or braided structure. Thus, as is well-known to those skilled in the art, there has been a long standing need for heat-recoverable coverings-which are

- 2 -~066~6~1 easy to apply, and yet are capable of forming a secure, intimate, impervious bond with the article which is covered.
U.S. Patents Nos. 3,243,211 and 3,396,460 disclose heat-recoverable articles capable of being applied to sub-strates in such a manner that a secure, intimate and impervious bond was formed. Furthermore, Belgian Patent No. 781,546 describes the use of heat-recoverable sleeves to repair breaks in m`ine cables. These specifications disclose, inter alia, a heat-recoverable, hollow article provided with a fusible insert or liner. If the liner is positîoned in abutting relationship with both the recoverable member and the substrate to which the recoverable member i8 to be applied, a heat-induced change, i.e., recovery, of the recoverable member will urge the fusible member toward the substrate and bring it into compressive abutment therewith.
In order, however,-to obtain a secure, intimate and impervious bond between the recoverable member and the substrate, the interposed fusible mem~er must become "fluid~, that is it must be reduced in viscosity to an extent sufficient for it to flow and "wet" the adjacent surfaces of the substrate and of the recoverable memker and thereby form a bond therebetween. With polymeric substances, the term "flow temperature" may be used to denote the temperature at which the polymer has a sufficiently low viscosity to "wet" surfaces it contacts. With substantially crystalline polymers the flow temperature approximately corresponds to the melting point of the polymer and the melting point is taken herein as the flow temperature of )66 ~6~
both crystalline ~d non-cryst~llir.e polymers. ~hus to achieve a good bond sufficient heat should always be applied to the fusible insert or liner to raise it above its melting point.
Under circumstances where the recoverable member i8 thin and lts heat-recovery temperature substantially greater than the melting point of the fusible liner this iB readily achieved.
When, however, thick recoverable members and/or comparatively high melting fusible inserts are used, an uns~illed worker irequently will not apply su~iicient heat completely to melt the iusible liner. ~his is, of course, highly undesirable since the liner will then not fully wet the suriaces oi both the sub-strate and the heat-recoverable member, and a sufficiently secure, intimate and imprevious bo~d may not be iormed there-between.
The present invention provides a method oi covering a substrate, which method comprises 80 positioning the sub-strate, an insert, and a iirst, heat-recoverable,member that the substrate is i~ the direction of recovery oi the heat-recover-able member and, on recovery oi the heat-recoverable member, at lesst part oi the insert will be urged towards the 3ubstrate, (~
the i~sert eitherlbeing corrugated and comprising a material that i8 fusible or a material that becomes less vi~cous on being heated to a temperature above the storage temperature (~) orLcomprising a second member having at least one protuberance on a sur~ace thereof, the second member comprising a material that i8 fusible or a material that becom~s less viscous on being heated to a temperature abo~e the storage temperatuL~e, the protuberance or corrugation being-of such a size and shape that it can be detected through the heat-recoverable member ; 30 after recovery of the heat-reco~èrable member and be~ore .

,~;

`- lO~;G469 application o~ a qu~ntity of heat which is su~ficient to cause the ~aid material or the second member to ~low and being capable o~ indicating when su~icient heat h~s been applied to cau~e the eaid material or the second member, and/or the protuberance or corrugation, to flow, recovering the heat-recoverable member, and applying heat until the protuberance or corrugation detec-able through the heat-reco~erable member indicates that the said material or the second member has flowed and/or indic2tes that the protuberance or corrugation has flowed.
o~
The insert, or a second member~f the~ protuberance forming part o~ the insert, may comprise a material which is strictly fusible, that is, which shows a sharp drop in vis-008i~y at a particular temperature on heating to a temperature above the storage temperature (that is, a material ~ith a definite melting point in the temperature range in question) or a material which is not strictly fusible, that is, does not ~how a sharp drop in ~iscosity at a particular temperature ~that is, a material without a de~inite melting point in the temperature range in question) but does become less vi~cous (that is more ilo~able) on heating to a temperature above the storage temperature.
In thiS description-the insert is sometime~ referred a to as/"liner". It is to be understood that the terms "insert"
and "liner`' include all members which can be positioned such that they will be interposed between a heat-recoverabie member and a ~ubstrate. Thus, ~or esample, i~ the heat-recoverable member iB a heat-expansible tube, the insert or liner mUBt be such that it can be positioned around the tube.
~he invention also provides an assembly suitable for ~Q use in the method of the invention, which a~sembly comprises ,. ,i ..

1 oti~ 9 a first,heat-recoverable,membsr and ~n insert positioned in abutting relation to, and in the direction o~recovery of, the heat-recoverable member so that, on recovery of the heat-recoverable member, at least par~ of the insert will be urged towards a substrate po3itioned, in use, in the direction of recovery of the heat-recoverable member, the insert either (A) being corrugated and comprising a material that i9 fusible or a material that becomes less viscous on being heated to a tem-perature above the ~torage temperature or(~comprising a second member having at least one protuberance on a surface thereoi, the second member comprising a material that is fusible or a material that becomes less viscous on being heated to a tem-perature above the storage temperature, the protuberance orcorrugation being of such a size and shape that it can be detected through the heat-recoverable member after recovery of . the heat-recoverable member but before application of an amount o~ heat which i~ ~ufficient to csuse the said material or the seoond member to flow, and being capable of indicating when suificient heat has been applied to cause the said material or ~econd member, and/or the protuberance or corrugation, to flow.
~ he invention further provides an assembly which comprises a iirst, heat-reco~erable, member and an insert poQitioned in abutting relation to and in the direction of recovery of, the heat-recoverable member 80 that, on recovery as of the heat-recoverable member, at least part of the insert will be urged toward~ a substrate positioned, in use, in the direction of reco~ery of the heat-reco~erable member, the insert ~ither/being corrugated and comprising a material that i8 fusible or a material that becomes le~s vi~cous on being heated to a temperature above the storage temperature or ~) comprising a second member having at least one protuber~nce on ~ 6 1C~6~69 a surface thereof, the ~econd member comprising a material that is fusible or a material that becomes leæs viscous on being heated to a temperature above the storage tem~erature, the protuberance or corrugation being capable of indicating -when sufficient heat has been applied to cause the saidmaterial or the second member, and/or the protuberance or corrugation, to ilow, and the protuberances or corrugation being detectable through the heat-recoverable member, and al80 provides a method of covering a substrate, which comprises so positioning the substrate, an insert, and a heat-recoverable member that the substrate is in the direction of recovery of the heat-recoverable member and, on recovery oi the recoverable member, at least part o~ the insert will be urged towards the substrate, the insert comprising a ~usible member and a plurality oi protuberances on the suriace of the ~usible member iacing the heat-recoverable member, the pro-tuberances being of such a size and shape that they can be de-tected through the heat-recoverable member aiter recovery o~
the heat-recoverable member and before application of a quantity oi heat which is suf~icient to cause the ~usible member to flow, and applying heat until the protuberances detectable through the heat-recoverable member disappear and indicate that the ~usible member has ~lowed.
~hus, in accordance with the invention, a member having protuberances on at least one sur~ace may be dispo~ed between a heat-recoverable sleeve and a substrate over which the sleeve is to be recovered. When the sleeve has been recovered but insufficient heat applied to make the member ilowable, the protuberances iorm detectable bump~ on the outer surface oi the sleeve indicating that more heat should be added to render the member flowable.
In this s~eci~ication, a material is said to ~low - 6a -.... . .. ~

1066~69 or to be flowable if it has substantially no stability of form under the pressure exerted on it by the recoverable member.
The invention makes it possible to provide a composite structure comprising a hollow heat-recoverable sleeve and a liner and a method of using same whereby even the most unskilled workman will be certain that sufficient heat has been applied to render the liner completely flow-able and thereby bond said recoverable sleeve to any work-p~ece t~1~scope within same. The invention also makes itpossible to provide a means whereby simple visual and/or tactile examination of the workpiece after heating of the aforementioned composite structure to encapsulate said workplece will be sufficient to determine if sufficient heat has been applied to render the liner flowable.
Although the following discussion will be directed primarily towards heat-recoverable members of tubular form (sometimes for convenience referred to as "sleeves" or "jackets"), it should be understooa that the present invention is equally applicable to and therefore encompasses structures wherein the heat-recoverable member is in the form of an end cap (for example, a cup), a T, X or Y, a ring or any other hollow configuration having at least one open end which can receive a substrate workpiece. Furthermore, the heat-recoverable member may be either heat-shrinkable or heat-expansible.
According to the present invention, the surface of a second member or liner is provided with a protuberance, or a plurality ~ separate upstanding protuberances, which may be formed fram either the same material as the second member 1066~69 or other compatible material (as hereinafter defined).
These protuberances may be present on either the surface of the second member aisposed towards the substrate or the surface disposed towards the heat-recoverable member, or both. If the heat applied to effect recovery of the heat-recoverable member is sufficient to also render the second member flowable, then the protuberances will melt and the recovered composite structure will have a smooth outer surface (for example, the outer surface of an encapsulating sleeve will be smooth). eonversely, if the amount of heat supplied is sufficient to effect reeovery of the heat-recoverable member, but insufficient to render the second member completely flowable, then the protuberances on the member will not melt and will form corresponding bulges showing on the surface of the recovered member. Even under conditions of poor visibility, such bulges can readily be felt by running the hand over the recovered member. The heating referred to in this specification as being required to effect recovery of the heat-recoverable member and flowing of the second member may be by any positive application of heat, for example, radiation heating, in-duction heating, electric resistance heating or heat generated by an exothermic reaction.
~he number, form and manner of disposition of the protuberances on the second member according to the in-vention is not critical provided the basic objective of the invention is adhered to. With respect to number, obviously if only a very limited number of protuberances are present, the operator a~ter recovery will be less certain that all the $usible liner, including the areas thereof which are ~66~69 furthest from any protuberance, has been sufficiently heated. It i8 therefore apparent that sufficient protu-berances should preferably be present so that their disappearance on heating i8 a clear indication that all of the second member has been rendered flowable. Likewise, to achieve this objective the protuberances are preferably distributed over substantially the entire surface of the second member. Such distribution can be random or in any conceivable geometric pattern. With respect to the form of the protuberances, they can be, for example, discrete (for example bumps or pimples) or in the form of continuous or discontinuous lines (for example, ridges). Preferably such bump~ or ridges will be sharp sided and relatively high in proportion to their cross-sectional area so that if they ?5 are not fully melted they will form readily apparent corresponding bumps or ridges on the surface of the recover-able memker. Thus it is preferable that the height of the protuberances be equal to at least about the diameter or-.
width, as the case may be, of the base of the protuberance.
It is further preferred that the height of the protuberances be at least about equal to the thickness of the-recovered member with which they are associated. Obviously, the most appropriate nu~ber and form of the protuberances will vary with the thickness and shape of the recoverable member and the contemplated heating means and for any given type of heat-recoverable member can readily be determined by simple routine experiment.
The inserts can be functionally combined with the heat-recoverable member in any suitable manner. For example, the insert material may be applied to either the _ g _ 1066~69 heat-recoverable member or to the substrate as a coating thereon with the protuberances being disposed on either or both surfaces of the insert. For example, the insert can be coated on the inner surface of the heat-recoverable member, i.e., the surface which is disposed towards a substrate telescoped therewithin, the outer surface or both. Normally, the protuberances will be present on the surface of the fusible insert which i8 not bonded to the heat-recoverable member and will therefore be disposed towards the substrate. Conversely, if the insert is applied to the outer surface of the substrate the protuberances will typically be on the other surface of the insert, being thereby disposed towards the inner surface of the enveloping heat-recoverable member. However, if desired, the side containing the protuberance(s) may readily be bonded to the substrate or sleeve, for example, by bonding the liner at points between the protuberances. Alternatively, the - insert in sheet form can first be wrapped around the substrate followed by telescoping the encased substrate within the sleeve. Or, a separate integral tube of insert can be interposed between the substrate and the heat-recoverable member. Under these circumstanees the insert can have protuberances present on either or on both of its surfaces, that is, the surface disposed towards the substrate and/or on the surface disposed towards the heat-recoverable member.
If the insert is to be positioned on the inner surface of the heat-recoverable member this would, of course, be done subsequent to the deformation of said member to its heat-recoverable condition. -If desired, although this is 1066~69 not preferred, the insert need not coat or envelop the entire surface of the substrate or coat the entire surface of the heat-recoverable member but can be deposited on either the substrate or heat-recoverable member in the form of rings, strips or other discontinuous areas of material on the substrate outer surface or jacket inner surface, respectively.
In general, the protuberances will be of the same material as the second member and will have the same melting point as the second member. However, in some cases, it may be desirable for the protuberances to melt or flow at a temperature different from that of the rest of the liner.
For example, the protuberances may melt or flow at a temperature higher than the temperature at which the rest of the liner melts or flows. In such a case, there would be a heat margin, thus insuring that the rest of the liner had melted or flowed when the protuberances di~appeared.
Further, if the protuberances melt at a temperature higher than the melting temperature of the rest of the liner, they may dig into either the substrate or the sleeve thus providing for maintenance of good gripping between the liner and substrate, liner and sleeve or all three prior to fusing of the liner. Indeed, the protuberances may be infusible at the heating temperatures so that they remain in contact with the substrate and/or sleeve after the rest of the liner has melted. For this purpose, pieces of, for example, metal, ceramic or a thermosetting plastics material, which may be applied, for example, by sprinkling them onto the insert, m~y be used as protuberances, protuberances which mechanically engage the sleeve and/or 106G~6~
the substrate may increase the mechanical strength of the joint. In particular, when the substrate comprises two articles having a joint or splice therein, such protuber-ances may provide mechanical reinforcement of the joint or splice against stress in use and may assist in preventing, for example, ~ngitudinal or torsional slippage.
Alternatively, the protuberances may melt or flow at a temperature lower than the melting or flowing temperature of the second member. Use of such lower melting or flowing protuberances may be desirable where timed heating is to occur. For example, when applying sleeves with fusible liners to cold pipelines, it is desirable to heat the sleeve covering the pipeline for a set period of time after a predetermined temperature has been reached. Thus, if the protuberances are set to melt at the predetermined temperature, timing can be started from that point.
The protuberances may be used for purposes other than indicating whether fusing of the second member has occurred. ~hus, it is sometimes desirable to have a layer of foamed material as a liner for imparting desir~ dielectric properties. The protuberance~ may be fusible or hollow and fusible so that they allow sufficient volume for controlled foaming of the balance of the liner. Thus, foaming agents placed in the liner could result in the production of a foam which would occupy, in part, the space originally occupied by the hollow protuberances.
The protuberances on the second member can be formed in a wide variety of ways, the choice being primarily dependent upon whether the insert is to be used as a separate sheet or tube or on the recovèrable member 6~

or substrate, as described above. Where the insert is used in the form of a separate sheet or tube, such a sheet or tube may be prepared by extrusion. Thus, the sheet or tube may be extruded using a die shaped to extrude a sheet or tube profile with ridges integrally formed thereon. Alternatively, a transfer coating apparatus can be used to embo~s any desired pattern of protuberances on either or both of the sheet surfaces. A tube, sheet or a coating of material can be provided with protuberances by sprinkling pellets, preferably of the insert material, onto the surface of the tube, sheet or coating which will preferably be warmed sufficiently to ensure adherence of the pellets. A tube interiorly coated, that is, lined, with a suitable material can be provided with internal ridges, either longitudinal or helical, by passing the lined tube over a vertical spray head which i8 received within the tube and sprays molten material onto the interior surface of the second member.
If the lined tube is simultaneously rotated as it traverses the spray, helical ridges are formed. Alternatively, an internal rotating spray head can be used to provide a series of ridges on the inside surface of the second member where the tube is stationary and the head rotates and then either the tube or the head is displaced in stages longitudinally. Another method is to partly heat-recover a heat-recoverable tube with a liner onto an engraved mandrel which will thereby emboss any desired pattern of ridges or bumps on the liner inner surface.
Under some circumstances, it may be desirable to _ bring the insert to a temperature somewhat higher than its flowing or melting point or range. In these cases, the 1066~69 protuberances may be made by sprinkling or otherwise app~ying, as described above, onto the surface of the second member protuberances of a material with a melt or flow temperature higher than that of the second member,the material being compatible with the second member. In some cases, the desired temperature corresponds to the softenlng temperature of a cable upon which the heat-shrinkable jacket is being applied. The term "compatible", as used herein, merely in-dicates that at the melting or flow temperature of the higher melting protuberance material, said material will become dissolved or otherwise dispersed into the material of the second member when the latter is flowable. In many instances the melting point or flow temperature of the protuberances is substantially the same as that of the second member so that flowing and elimination of the protuberances indicates flowing of the second member. In other instances (see above) the melting point or flow temperature of protuberances may advantageously be sub-stantially above or below that of the second member.
The heat-recoverable member used according to the invention may be extruded or moulded in the desired shape.
Where a simple tubular shape is desired, it may also be fabricated from a flat sheet of material simply by rolling it into a tube and suitably sealing the seam. Preferably, the heat-recoverable member comprises a material having the property of elastic memory, for example those materials disclosed in United States Specification No. 3,086,242.
As is well-known to those skilled in the art, materials having the property of elastic memory are dimen~ionally heat-unstable and may be caused to change shape and/or 1~66~69 dimension simply by the application of heat. Elastic memory may be imparted to polymeric materials by first extruding or otherwise moulding the polymer into a desired shape. The polymer is then crosslinked by exposure to high energy radiation, for example, a high energy electron beam, exposure to ultra-violet irradiation, or by chemical means, for example, incorporation of peroxides when polyolefins are used. The crosslinked polymeric material is then heated and deformed and then locked in that deformed condition by quenching or other suitable cooling or, alternatively, the same process can be carried out at room temperature by using greater force to deform the polymer. The deformed material will retain its shape almost indefinitely until exposed to an elevated temperature sufficient to cause recovery, for example, approximately 250F in the case of polyethylene. Among the polymers which can be processed in this way are polyolefins (for example, polyethylene and polypropylene), polyamides, polyurethanes, polyvinylchloride, polytetrafluoroethylene and polyvinyl-idene fluoride. The property of elastic memory can also be imparted without actual crosslinking to materials having the properties of crosslinked polymers (for example poly-tetrafluoroethylene, polyolefins, or vinyl polymers) which have a sufficiently high molecular weight to give the polymer appreciable strength at temperatures above the crystalline melting point.
Suitable materials for the insert include inorganic fusible materials, for example, solder, and conventional thermoplastics materials, for example polyolefins (for example, polyethylene and polypropylene), polyamides (for 106~i~69 example, Nylon 6 and Nylon 66), polyesters (for example polyethylene terephthalate), and polyether sulphones (for example, 4,4'-phenylene ether sulphone). Particularly preferred are hot melt adhesives, for example those disclosed in German Offenlegungsschrift No. 2,347,799 filed in the name of Raychem Corporation and published 25th April, 1974. It is to be understood, however, that the present invention is not limited to the use of conventional thermoplastics as the fusible material and initially flowable thermosetting materials are also suitable. Materials such as epoxy resins, polyurethane resins, phenolformaldehyde resins and the like may, therefore, also be used either alone or in combination with a thermo-plastic material to form the insert.
The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure~ 1 and 2 are enlarged, fragmentary v~iews of two different liners according to the invention, Figure 3 is a view of a heat-recoverable sleeve, liner and substrate, Figure 4 is a view of a substrate having positioned around it a liner and a heat-recoverable sleeve;
Figure 5 is a view illustrating bumps visible through the sleeve when the liner has not been heated sufficiently to flow:
Figure 6 is a view illustrating a method of making a liner, 106~;~69 Figure 7 is a cross-section through a sleeve and liner illustrating embossing of the liner; and Fîgure 8 is a view, partly in cross-section, illustrating the formation of a liner having helical rid.g s.
Referring now to the drawings, Figure 1 shows a liner 1 which includes protuberances 2 in the form of bumps or pimples. m e liner is in the form of a sheet which could be wrapped around a substrate, but it should be understood that the liner could be in the form of a tube or could have any other desired shape. It can be seen that the pimples 2 are sharp and relatively high in relation to their cross-sectional area. Normally, when the lincr is placed in the direction of.recovery of a heat-recover-able member, the pimples are disposed away from the . member. If desired, however, the liner could be positioned with the pimples 2 disposed toward the.recoverable member Also, although only one side of the liner 1 is provided with protuberances, it could have protuberances on both sides.
Figure 2 shows a liner 1 which includes ridges~
These ridges may be discontinuous ridges 3 or continuous ridges 4. The ridges may also be placed on both sides of ~5 the liner and should be relatively high in relation to their cross-sectional area.
The use of the liner which includes protuber~nces is illustrated in Figure 3. A substrate 5 is inserted into a heat-rccoverable slceve 6 having an inner liner which comprises a fusiblc mcmber 7 with protuberanccs 8 illustrat~d 1066~6~

here as bumps. In this Figure, the liner is attached to the recoverable sleeve 6 and the protuberances are disposed toward the substrate 5 as illustrated, they could, however, be on the sleeve 3ide of the liner if desired.
In Figure 4, a substrate 9 is covered with a liner which includes a second member in the form of a tube 10. This liner includes protuberances 11 again illustrated as bumps. A recoverable sleeve 12 is then placed over the liner and heat-recovered. In this case, the protuberances are preferably disposed toward sleeve 12.
When either sleeve 6 or sleeve 12 is heat-recovered, the sleeve may recover before enough heat has been applied to cause the 3econd member to flow. In that case, the protuberances will be visible on the outer surface of the sleeve. This condition is illustrated in Figure 5. As can be seen, a substrate 13 is covered by a heat-recoverable sleeve 14. A second member 15 has not yet become flowable and, as a result, the protuberances are visible at 16 on the outer surface of heat-recoverable sleeve 14. When this condition exists, it can be seen and the workman applying the sleeve can thus readily determine, either visually or by feel, that insufficient heat has been applied and that more heat should be applied. When the outer surface of sleeve 14 becomes smooth, this indicates that the second member has reached a flowable condition, and that sufficient heat has been applied.
Figure 6 illustrates a method of manufacturing a liner. A sheet of fusible material 17 is warmed and then pellets of fusible material 18 are sprinkled onto the surface to form protuberances 19. The pellets should be i9 compatible with the material 17 so that they adhere thereto when material 17 is warmed.
A~ illustrated in Figure 7, protuberances can also be formed while using an engraved mandrel. A tube of heat-recoverable material 20 is provided with an inner sleeve 21 of insert material. The tube is then placed over a mandrel 22 having grooves or indentations 23 therein. The heat-recoverable sleeve is then partially heat-recovered over the mandrel. q~he heat causes the inner sleeve 21 to flow into the indentation 23 thus forming protuberances on the inner surface of the sleeve 21. The sleeves 20 and 21 are then removed from the mandrel, and a heat-recoverable tube 20 having an inner liner with protuberances on the inner surface is obtained.
A method for forming protuberance~3 in the form of ridges on the second member is illustrated in Figure 8. A
heat-recoverable tube is indicated generally at 24. It comprises an outer heat-recoverable sleeve 25 and an inner member 26. The member 26 has protuberances in the form of ridges 27. These ridges are applied by spraying fusible material through a spray head 28. The ridges 27 are formed helically by rotating tube 24 and at the same time moving it laterally. Alternatively, the spray head 28 ~uld-be rotated as tube 24 moves laterally.
In addition to the embodiments specifically disclosed in the Figures above, it should be understood that this invention is applicable to any type of pro-tuberance on the liner and any method of forming such a protuberance. Thus, protuberances in any form may be employed, the only restriction being that the protuberances 1~66~
be discernible by sight or feel when the heat-recoverable sleeve is re-covered without causing the second member to become flowable. Further, any method of forming the protuberances which is desired may be employed.
It should be understood that in the method and assembly of the invention the insert may be a fusible corrugated article which may have one or more corrugations.
It will also be appreciated that the invention is applicable to recovery over any type of substrate which may be in the form of one or more articles.

Claims (54)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of covering a substrate, which method comprises positioning the substrate, an insert, and a first, heat-recoverable,member that the substrate is in the direction of recovery of the heat-recoverable member and, on recovery of the heat-recoverable member, at least part of the insert will be urged towards the substrate, the insert either (A) being corrugated and comprising a material that is fusible or a material that becomes less viscous on being heated to a temperature above the storage temperature or (B) comprising a second member having at least one protuberance on a surface thereof, the second member comprising a material that is fusible or a material that becomes less viscous on being heated to a temperature above the storage temperature, the protuberance or corrugation being of such a size and shape that it can be detected through the heat-recoverable member after recovery of the heat-recoverable member and before application of a quantity of heat which is sufficient to cause the said material or the second member to flow and being capable of indicating when sufficient heat has been applied to cause the said material or the second member, and/or the protuberance or corrugation, to flow, recovering the heat-recoverable member, and applying heat until the protuberance or corrugation detectable through the heat-recoverable member indicates that the said material or the second member has flowed and/or indicates that the protuberance or corrugation has flowed.

2. A method as claimed in claim 1, wherein the second member is in the form of a coating on the heat-recoverable member.

3. A method as claimed in claim 1 or claim 2, wherein the protuberance flows on flowing of the second member.

4. A method as claimed in claim 1, wherein the protuberance is infusible at the temperature to which the assembly is heated to cause the second member to flow and the heat-recoverable member to recover.

5. A method as claimed in claim 4, wherein, after recovery of the heat-recoverable member and flowing of the second member, the protuberance mechanically engages the sub-strate and/or the heat-recoverable member to increase the strength of the joint between the substrate and the heat-recoverable member.

6. A method as claimed in claim 1, wherein the protuberance is infusible.

7. A method as claimed in claim 1, wherein, before heating takes place, the insert is positioned in contact with the substrate.

8. A method as claimed in claim 7, wherein the surface of the second member which is in contact with the sub-strate is free of protuberances.

9. A method as claimed in claim 1, wherein, before heating takes place, at least a substantial part of the insert is in contact neither with the heat-recoverable member nor with the substrate.

10. A method as claimed in claim 9, wherein both the surface of the second member which is presented to the heat-recoverable member and the surface of the second member which is presented to the substrate have at least one protu-berance thereon.

11. An assembly which comprises a first heat-recoverable,member and an insert positioned in abutting relation to, and in the direction of recovery of, the heat-recoverable member so that, on recovery of the heat-recoverable member, at least part of the insert will be urged towards a substrate positioned, in use, in the direction of recovery of the heat-recoverable member, the insert either (A) being corrugated and comprising a material that is fusible or a material that becomes less viscous on being heated to a temperature above the storage temperature or (B) comprising a second member having at least one protuberance on a surface thereof, the second member comprising a material that is fusible or a material that becomes less viscous on being heated to a temperature above the storage temperature, the protuberance or corrugation being of such a size and shape that it can be detected through the heat-recoverable member after recovery of the heat-recoverable member but before application of an amount of heat which is sufficient to cause the said material or the second member to flow, and being capable of indicating when sufficient heat has been applied to cause the said material or second member, and/or the protuberance or corrugation, to flow.

12. An assembly as claimed in claim 11, wherein the second member is in the form of a coating on the heat-recoverable member.

13. An assembly as claimed in claim 11, wherein the heat-recoverable member has the property of elastic memory.

14. An assembly as claimed in claim 11, wherein the heat-recoverable member comprises a crosslinked polymer.

15. An assembly as claimed in claim 11, wherein the heat-recoverable member is in the form of a tube.

16. An assembly as claimed in claim 11, wherein the surface of the fusible member which abuts the heat-recover-able member is free of protuberances.

17. An assembly as claimed in claim 11, wherein the protuberance has a height which is at least equal to the thickness of the heat-recoverable member,

18. An assembly as claimed in claim 11, wherein the insert comprises a thermoplastic polymeric material.

19. An assembly as claimed in claim 18, wherein the thermoplastic polymeric material is a polyolefin, a poly-amide, a polyester, or a polyether sulphone.

20. An assembly as claimed in claim 11, wherein the insert comprises a hot melt adhesive.

21. An assembly as claimed in claim 11, wherein the insert comprises an initially flowable thermosetting material.

22. An assembly as claimed in claim 11, wherein the insert comprises a foamable material.

23. An assembly as claimed in claim 11, wherein the insert comprises solder.

24. An assembly as claimed in claim 11, wherein the protuberance is infusible at the recovery temperature of the heat-recoverable member or at the temperature of fusion of the second member.

25. An assembly as claimed in claim 24, wherein the protuberance comprises a metallic, ceramic, or thermosetting plastics material.

26. An assembly as claimed in claim 11, wherein the insert comprises a plurality of protuberances, which may be the same as or different from one another.

27. An assembly as claimed in claim 26, wherein the protuberances are distributed over substantially the whole of the said surface.

28. An assembly as claimed in claim 11, wherein the insert is in sheet form.

29. An assembly as claimed in claim 11, wherein the insert is in the form of a tube.

30. An assembly as claimed in claim 11, wherein the protuberance is in the form of a bump.

31. An assembly as claimed in claim 11, wherein the protuberance is in the form of a ridge.

32. An assembly as claimed in claim 11, wherein the height of the protuberance is equal to or greater than the diameter or width, as appropriate, of the base of that protuberance.

33. An assembly as claimed in claim 11, wherein the protuberance is formed integrally with the second member.

34. An assembly as claimed in claim 11, wherein the protuberance has been formed by extrusion.

35. An assembly as claimed in claim 11, wherein the protuberance has been formed by embossing.

36. An assembly as claimed in claim 11, wherein the protuberance has been formed by warming a pellet of fusible material to cause it to adhere to said surface.

37. An assembly as claimed in claim 11, wherein the protuberance has been formed by a spray nozzle.

38. An assembly as claimed in claim 11, wherein the protuberance comprises a material that is fusible or a material that becomes less viscous on heating to a temperature above the storage temperature.

39. An assembly as claimed in claim 38, wherein the protuberance comprises the same material as the second member.

40. An assembly as claimed in claim 38, wherein the protuberance comprises a material which is different from the material of the second member.

41. An assembly as claimed in claim 40, wherein the material of the protuberance will, when flowable, dissolve or become dispersed in flowable material of the second member.

42. An assembly as claimed in claim 38, wherein the protuberance becomes flowable at a temperature which is not less than that at which the second member becomes flowable.

43. An assembly as claimed in claim 38, wherein the protuberance becomes flowable at a temperature which is substantially the same as that at which the second member becomes flowable.

44. An assembly as claimed in claim 38, wherein the protuberance becomes flowable at a temperature which is less than that at which the second member becomes flowable.

45. An assembly as claimed In claim 38, wherein the protuberance becomes flowable at a temperature which is higher than that at which the second member becomes flowable.

46. A method as claimed in claim 1, wherein the recoverable member and the insert are in the form of an assembly as claimed in claim 11.

47. A method as claimed in claim 1, wherein the recoverable member is a hollow body which is closed in cross-section.

48. A method as claimed in claim 1, wherein the insert is as specified in claim 20.

49. In combination, a heat-recoverable sleeve, a substrate, the sleeve being positioned over the substrate for heat-recovery into contact with the substrate, the sleeve having disposed adjacent to the inner surface of the sleeve a fusible liner comprising a fusible polymeric adhesive material having protuberances on at least one surface of the liner, the protuberances comprising a fusible material, the protuberances being of such size and shape that they form readily obvious bumps or ridges on the outer surface of the heat-recoverable sleeve after it has recovered into contact with the substrate but before application of a quantity of heat which is sufficient to cause the liner to flow, and upon application of sufficient heat, the protuberances and fusible liner flow to form a complete bond between the sleeve and the substrate.

50. In combination, a heat-recoverable sleeve, a substrate, the sleeve being positioned over the substrate for heat-recovery into contact with the substrate, the sleeve having disposed adjacent to the inner surface of the sleeve a fusible liner comprising a fusible polymeric adhesive material having protuberances on at least one surface of the liner, the protuberances comprising a fusible material having substantially the same flow temperature as that of the liner, the protuberances being of such size and shape that they form readily obvious bumps or ridges on the outer surface of the heat-recoverable sleeve after it has recovered into contact with the substrate but before application of a quantity of heat which is sufficient to cause the liner to flow, and upon the application of sufficient heat the liner flows to bond the sleeve to the substrate.

51. A method of recovering a heat-recoverable sleeve over a substrate comprising positioning the sleeve over a substrate, the inner diameter of the sleeve being larger than the outer diameter of the substrate, interposing a fusible insert of fusible polymeric material between the sleeve and the substrate, the insert having protuberances on at least one surface, the protuberances comprising a fusible material having substantially the same flow temperature as that of the liner and being of such size and shape that they form readily obvious bumps or ridges on the outer surface of the heat-recoverable sleeve as it is being recovered, applying heat to shrink the heat recoverable sleeve until bumps on the surface of the re-coverable sleeve are observed and continuing application of heat to the heat-recoverable sleeve until bumps are no longer observed whereby the insert flows to form a complete bond between the sleeve and the substrate.

52. An assembly as claimed in claim 11, wherein the heat-recoverable member comprises a hollow body which is closed in cross-section.

53. An assembly which comprises a first, heat-recoverable, member and an insert positioned in abutting relation to and in the direction of recovery of, the heat-recoverable member so that, on recovery of the heat-recoverable member, at least part of the insert will be urged towards a substrate positioned, in use, in the direction of recovery of the heat-recoverable member, the insert either (A) being corrugated and comprising a material that is fusible or a material that becomes less viscous on being heated to a temperature above the storage temperature (B) or comprising a second member having at least one protuberance on a surface thereof, the second member comprising a material that is fusible or a material that becomes less viscous on being heated to a temperature above the storage temperature, the protuberance or corrugation being capable of indicating when sufficient heat has been applied to cause the said material or the second member, and/or the protuberance or corrugation, to flow, and the protuberances or corrugation being detectable through the heat-recoverable member.

54. A method of covering a substrate, which comprises so positioning the substrate, an insert, and a heat-recoverable member that the substrate is in the direction of recovery of the heat-recoverable member and, on recovery of the recoverable member, at least part of the insert will be urged towards the substrate, the insert comprising a fusible member and a plurality of protuberances on the surface of the fusible member facing the heat-recoverable member, the protuberances being of such a size and shape that they can be detected through the heat-recoverable member after recovery of the heat-recoverable member and before application of a quantity of heat which is sufficient to cause the fusible member to flow, and applying heat until the protuberances detectable through the heat-recoverable member disappear and indicate that the fusible member has flowed.