CA1051987A

CA1051987A - Heat recoverable closure assembly and method

Info

Publication number: CA1051987A
Application number: CA236,473A
Authority: CA
Inventors: James E. Jervis
Original assignee: Raychem Corp
Current assignee: Raychem Corp
Priority date: 1974-09-27
Filing date: 1975-09-26
Publication date: 1979-04-03
Also published as: GB1529352A; AU8523375A; GB1529357A; JPS5185544A; IT1042913B; DE2543358A1; FR2286302A1; MY8200226A; HK62881A; AU510534B2; FR2286302B1

Abstract

A B S T R A C T

An elongate, tubular closure assembly for conduits and the like including one or more sheet-like closure members capable of being deformed into tubular configurations with abutting edge regions and retaining members or channels capable of holding the abutting edge regions of the closure members. The closure members are of dimensionally heat-unstable material which, when assembled with the channel members, may be heated to recover to hold an enclosed object tightly. Wedge-shaped ridges may extend along each of the abutting edge regions of the closure members. The edge regions are engaged by converging legs of the retaining members to complete the closure. The edge regions may deform as part of the heat recovery process to form a tight seal within the retaining members.

Description

1o51987 The present invention relates to a heat-recoverable closure a~sembly and to a method for in~talling such a member.
There are many instances where it is desirable to provide a protective and/or insulative closure on a substrate (such as an elongate conduit or pipe) which does not have an accessible end over which conventional tubing can be drawn.
Consequently, it is necessary to provide a split closure which may be po~itioned around a continuous elongate object and then joined at the edges. Two examples of such split closures incorporating heat-recoverable material are disclosed in United States Patent Specifications Nos. 3,379,218 and 3,455,336.
Heat-recoverable closure assemblies which can be positioned around a substrate and then joined at the edges generally require a relatively strong retaining device for holding the abutting or overlapping edges of the closure member during the heat shrinking process. Such retaining devices are also used to insure the integrity of the closure after it has been finally assembled around the object. The use of heat-recoverable material complicates the proper closure of such assemblies because of the inherently flexible nature of the heat-recoverable materials normally used in such applications. This flexible nature allows the closure member to be distorted under the high forces resulting from heat-re~overy of the closure member about an enclosed object.
Such distortion normally results in reduced resi~tance to extraction of the closure member from the retaining device.

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Such materlal is also liable to be cut when ~tres~d over oharp ob~ect~ such as the ~harp edges ~reguently ~ound i~ conventional retainers.
It 18 also important that heat-re¢overable closure assemblies, oi the type discussed in the pre¢eding paragraph, provide a ~eal along the joint or ~oints to prevent the intrusion o~ -moisture and the like. Thus, close tolerances between-clo~ure retainer~ and closure member~ are oiten required as well as relatively complicated shapes ior both the closure members a~d the reta~ng devices. Such close tolerances and complicated shape~ adversely a~ect the cost o~ manu~acturing and assembline ~; o~ the closure assemblie~. Furt~er, i~ close tolerance~ and ca~eiul as~embly procedures are not adhered to, such closure aseemblles mag fail either during heat-recovery o~ t~o clo~ure 15 members or at some later period. Furthermore, the buIk o~ such ~`
` aesemblies can render them impractical ~or use ~ith sm~ll diameter sùbstrates. ~-he prese~t in~ention provides a closure a~se bly~which `
~ comprise~ a closure member comprising dimensionHlly héat-unstablé; ?`~ ` ~ 20 material, the closure member ha~ing two oppo~ite edge regione~
~hat can be brought into abutti~g relationship with aoh other, and fastèning mean~ ior rece?i~ing at least a part o~ the edge~ -`
;` ~ regionsand maint~inlng them in abutting relatio~hip duri~g r~co~erg of the clo~ure member, the edge regions and the ia~tening means being such that, before insta}lation Or the a~sembly and reoo~erg o~ the member the rastening mean~ may be posit1oned o~er the abutting edge regions, the space derined bg the i te~ing ~ 051g~7 means having a ~;ha~e or di~en~ion that doe~ not conform clo~ely to that of the abutting edge reeions and ~uch that, during installation and recovery, the dimensions o~ the fastening me~ns and/or the abuttin~ edge region~ aré cha~geable to cau~e their shapes to conform more closely.
Advantageously each edge region comprises an outwardly extending wedge shaped ridge having one sur~ace mating with the corresponding surface of the other edge region. Preferably the angle of the wedge is about 45 so that each ridge also comprises first and second surfaces dispo~ed at that angle to the`matlng sur~ace.
Preferably the mating surfaces comprise means for reducing sliding between them. Such means may be, for example, interlocking or interengaging means. The surfaces of the recoverable member be t5 or of the fastening means or both may/provided with an adhesive or sealantO
~ he edge regions are advantageously dimensionally heat unstable and are preferably capable of increasing in thickness on the application of heat. Advantageously if they are already wedge shaped they will change to increase the angle of the wedge and if they are not already wedge shaped they will become so on application of heat, at least in those portions which will be ln contact with the free ends of the fastening means.
Advanta~eously the edge regions are capable of for~ing ridges when they are heated ~hile being maintained in abutting relationshipO

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lOS1987 Advantageously the ~a~tening means comprise~ a central portion and t~o ~ide portions, each sidc port~on be~ng ~uch that it is de~ormable during installation to contact a sur~ce o~ the ridge. In certain circumstance~, the ~hape~ o~ the ~a~ten~ng m~ans and the edge regions may conform closely before installation and recovery, the fastening means being de~ormahle to cause it to enclose the edge regions even more closely.
~ he closure member may comprise a plurality of sheets of dimensionally heat-un~table material, each o~ the sheets having two ed~e reglons each o~ which can be brought into abutting rclationship with an ed~e region of another sheet.
~ he in~ention al~o provides a method of joining two opposite edges of a closure member comprising dimensionally heat-unstable material, which comprises bringing the edge regions into abutting relationship with each other, positioning ~astening mea~s to receive at least portions of the edge regions, and heating the edge regions whereby they change in dimensions to conform more closely to the dimension of the space defined by the ~astening means, the method advantageously employing the advantageous forms o~ the assembly.
Preferably the remainder of the closure member is heated to cause recovery over the substrate to be protected and most pre~erably this is effected after at least partial recovery o*
the ed~e regions. The invention also provides a substrate a cable splice covered by the assembly or the method of the in~entionO

~ 5 lOS1987 The present lnvention al~o provides an elongate, tubular cloæure aæ~embl~ for condult~ and the like ~ncluding one or more ~heet-like clo~ure members capable o~ being de~ormed into tubular configurations with abutting edge regions and retaining members or channel~ capable of holdi~g the abutting edge regions of the closure memberc. The closure members are of dimensionally heat-unstable material which, when assembled with the channel member~, may be heated to advantageou~ly recover to tightly hold an enclosed ob~ect. Wedge-shaped ridges may extend along each of the abutting edge regions of the closure members. The edge regions, sometimes referred to herein as edges, are engaged by converging legs of the retaining members to complete the closure. The edge regions may deform as part of the heat recovery process to form a tight seal within the retaining members.

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~051987 The closure assembly of the pre~ent invention may include one or more closure members and one or more retaining device~. The retaining devices form channels which may be positioned over abutting edges of heat-recoverable closure S members to form tight joint~ that will withstand and, preferably, be enhanced by, heat-recovery of the closure members. Ridges may be created along the edges of the clo~ure member~ to engage the closure members more securely with the retaining device~. These ridges may be formed during fabrication of the elongate closure members or during the heat recovery step. The edges may be such as to present a small cross-section for easy location in the channel-like retaining device, and upon recovery, may expand to become tightly held within the retaining device.
lS This expansion may either increase the width of existing ridges or create ridges to fit more closely into the interior of the retaining device and thus become tightly held. In this way, integrity of the closure may be assured without the need for close tolerances and careful attention to assembly detail.
~he forces which come into effect during heat-recovery of the closure members may also operate to insure integrity of the joint between abutting portions of the closure members. Wedge-shaped ridges, designed to create an ever-increasing width of material being pre~ented to the retaining device as two contiguous edges of the closure member or members are extracted therefrom, have 1051~7 been found to be advantageous. Thus, the flexible nature of the recoverable material can be prevented from resulting in a distortion which would decrease the ability of the member to resist extraction. me ridge S configuration also tends to resist moment forces which would otherwise cause counter-rotation of two retained edges from the retaining device. The edges of the clo~ure members may be fabricated, along with the main body of the recoverable members, such that advantageous dimensional change of the edge~ will occur once these have been positioned in the retaining device and subjected to sufficient heat to initiate recovery. In this way, a ridge may be developed or reconfigured on each edge only upon the heat recovery of the edge within the constraining confines of the retaining device. With this available flexibility in the closure member edge, it becomes possible to use a loose-fitting retaining device which may be more easily slipped over edge regions of the closure member and which does not require crimping.
Accordingly, the present invention makes it possible to provide an improved heat-recoverable closure assembly and method, and a heat-recoverable closure assembly having an improved joint.

10519~7 The invention will now be de~cribed, by way of example only, with reference to the accompanying drawing~, ih which:
Figure 1 i9 a per~pective view of a closure as embly according to the present invention during installation, Figure 2 is an end view of a closure member before installation, Figure 3 i~ an end view of a closure assembly according to the pre~ent invention during in~tallation, Figure 4 is an end view of an assembled closure according to the present invention7 Figure 5 is an end view of a tool which may be used in the installation of the closure assembly of the pre~ent invention7 Figure 6 shows part of a second embodiment of a closure member used according to the present invention7 Figure 7 sh.ows the use of multiple closure sheets and retaining devices for a single closure7 Figure 8 ~8 an end view of a further embodiment of the invention illustrating unrecovered edges of a closure member in a retaining device7 Figure 9 is an end view of the embodiment of ~igure 8 illu~trating the closure member after recovery7 Figure 10 is an end view of yet another embodiment of the invention illustrating unrecovered edges of a closure member in a retaining device7 and lOSlg87 Figure 11 is an end view of the embodiment of Figure 10 ~ strating the closure member after recovery;
Figures 12 and 13 illustrate edges of a further form of closure member in a retaining device before and after recovery respectively.
Referring now to the drawings, Figure l shows a closure member generally designated by the reference numeral l0. The closure member 10 conprises a single elongate sheet of material capable of being deformod into a tubular configuration as illustrated in Eigure 1. The present inven-ln tiOII applies equally to a multiple sheet closure member as seen, for example,in Figure 7. A specific embodiment is illustrated in Canadian Application No. 236,482 of Horsma et al, filed September 26, 1975. The closure member 10 comprises dimensionally heat-unstable material. In general such material has the property of elastic or plastic memory imparted thereto to form a heat-recoverable member. The closure member l0 may be converted to the dimensionally heat-unstable, heat-recoverable, state by heating it to above its crystalline melting temperature and stretching it. Stretching the closure member 10 also causes it to be reduced in thickness. The material is then cooled in this stretched condition; it will then retain this stretched ~ , condition until it is again heated to the crystalline melting temperature.
0nce heated to that temperature, the closure member l0 will attempt to recover to its original shape and will tightly conform to an elongate object placed therein. Examples of materials to which the property of heat-recover-ability msy be applied may be found in United States Patent Specifications Nos. 2,027,962 and 3~086,242. Polymerîc materials which have been cross-linked by chemical means or by irradiation, for _9_ ;`

1(~51987 example, with high energy electrons or nuclear radiation, are preferred for use in the present invention.
~ 8 can be seen most clearly from Figure 2, the closure member 10 comprises a ~heet of heat-recoverable material 5 which may have wedge shaped ridges on one side thereof extending lengthwice along two parallel edges 12 and 14 of the sheet.
The width and length of each closure member 10 will depend on its ultimate use. The width of the sheet between the ridges must be ~uch that it will easily wrap about the object to be enclosed when in the expanded state and yet shrink tightly to enclose the object when heated to a temperature above the crystalline melting temperature.
The elongate parallel edges 12 and 14 of the closure member 10 include wedge-shaped ridges 16 and 18 positioned on one side of the closure member 10 and flat mating surfaces 20 and 22 on the opposite side of the ~heet from the wedge shaped ridges 16 and 18, In the embodiment of the invention illustrated in Figures 1 to 5, the flat mating surfaces 20 and 22 extend across the entire inner surface of the closure member 10 to form a single continuous surface.
To enclose an elongate object (substrate) with the closure member 10, parallel edges 12 and 14 are brought together about the object with the wedge shaped ridges 16 and 18 extending outwardly therefrom. In this configuration, the flat mating surfaces 20 and 22 are contiguous and the wedge-shaped ridges 16 and 18 form a bead which may be gra~ped by a retaining device.
Referring now to Figures 1 and 3 to 5, a retaining device generally designated 24 is employed with the closure member 10 lOS1987 to form an elongate tubular closure. The retaining device form~ an elongate channel having walls 26 and 28 (see Figure 3) which extend outwardly from an apex 30. The walls 26 and 28 are preferably at an angle with respect to one S another to accommodate the upper portion of the bead formed by the wedge shaped ridges 16 and 18. Depending from the walls 26 and 28 respectively are leg~ 32 and 34. The legs 32 and 34 terminate respectively in flanges 36 and 38 which extend outwardly from the channel defined by the walls 2~ and 28 and the legs 32 and 34. The distance between the legs 32 and 34 is sufficient to allow the retaining device 24 to be placed over the bead formed by the wedge-shaped ridges 16 and 18.
Once the retaining device is in po~ition, the legs 32 and 34 may be crimped inwardly 80 thàt they are mutually convergent.
lS This condition is best illustrated in Figure 4. When the retaining device 24 has been forced around the bead formed by the wedge-shaped ridges 16 and 18, the legs 32 and 34 act to engage the wedge-shaped ridges to prevent their separation.
The flanges 36 and 38 are employed to prevent the lower edge~
of the legs 32 and 34 from biting into the closure member 10.
In assembling the closure, the closure member 10 is wrapped about the elongate object to be enclosed so that flat mating surfaces 20 and 22 are brought into contiguous relation-~hip. An adhesive or sealant may if desired by employed between the mating surfaces 20 and 22 and between the closure and substrate to insure a leakproof seal. Such an adhesive may be heat-activated in order that it will better form a seal during the heat-~hrinking process. With the mating surfaces 20 and 22 lOS~9~7 positiorled together, the wedge-shaped ridges 16 and 18 form a bead over which the retaining device 24 i8 positisned. Thç
legs 32 and 34 are then forced inwardly to fit tightly about the wedge-shaped ridges 16 and 18 and thereby reta~n the elongated parallel edges 12 and 14 in contiguous relationship.
When the legs 32 and 34 have been brought into the desired poqition, heat is then applied to the closure member 10 to cause it to shrink about the elongate object being enclosed.
The heat-recoverable material within the retaining device 24 may, if desired, be allowed to change dimensionally on heating to fill the wedge-shaped portion of the cavity within the retaining device to form or enhance the bead associated with the edges of the closure member. Once the shrinking is completed, the temperature of the closure member 10 is allowed to drop below ~he crystalline melting temperature of the material.
Normally, tension still remains in the closure member which continues to tightly hold the object enclosed. The tension also tend~ to separate the edges 12 and 14 if these are not properly constrained.
Instead of being ~uch that the legs 32 and 34 must be forced inwardly to contact the wedge-shaped ridge~, the retaining device 24 may be preformed to conform closely to the bead formed by the wedge-shaped ridges 16 and 18. The retaining device may then be slid over the end of the bead into place and further crimped if desired to tightly hold the edges 12 and 14.
Referring in detail to the mechanical relations~ips between the wedge-shaped ridges 16 and 18 and the enclosing 105~987 legs 32 and 34, a closure assembly i~ formed which assures a compressed joining of the flat mating surfaces 20 and 22~ It is believed that thi~ joint is enhanced by the residual tension remaining after the heat-recovery process. The wedge-shaped ridges 16 and 18 extend outwardly defining first thrust surfaces 40 and 42 (~ee Figure 3). Second surfaces 44 and 46 extend upwardly to the edge of the closure member 10. These surfaces 40, 42, 44 and 46 are all, in the embodiment of the invention shown in Figures 1 to 5, disposed at 45 with respect to the mating ~urfaces 20 and 22. However, a broad range of angles is believed to be acceptable.
When the legs 32 and 34 are forced inwardly about the wedge-shaped ridges 16 and 18, the inner surfaces of the legs 32 and 34 engage the thrust surfaces 40 and 42, preventing the extraction of the edges 12 and 14 of the closure member 10 from the retaining device 24. Tension forces, imposed during the heat-recovery of the closure 10 and remaining after recovery has been completed, tend to withdraw and rotate the edges 12 and 14 from the retaining device 24. The converging nature of the assembled retaining device 24 at legs 32 and 34 as well as the wedge-shaped of the bead formed by ridges 16 and 18, however,.
insure proper closure between the mating surfaces 20 and 22.
Thus, the closure member 10 is placed in tension tending to withdraw the edges 12 and 14 from the retaining device 24, the thrust surfaces 40 and 42 are forced against the inner side of legs 32 and 34. This tends to force the mating surfaces 20 and 22 together forming a tight seal. The tendency for the edges 12 .

and 14 to rotate out of the retaining device 24 also further tightens the seal. The wedge-shaped ridges 16 and 18 extend upward between the second urfaces 44 and 4~, these extensions of the wedge-shaped ridge~ 16 and 18 between the second surface~
44 and 46 and the flat mating surfaces 20 and 22 re~ist such rotation. Thus, the mating surfaces 20 and 22 are forced together. In this way, the seal is tightened and the edges 16 and 18 are held within the retaining device 24.
The upward extension of the edges 12 and 14 to surfaces 44 and 46 also create~ a geometrical 3tructure which cannot be easily pulled from the retaining device. The cross-sectional width of the wedge-shaped ridge continues to increase with increasing distance from the open end of the crimped retaining device as meaqured along perpendiculars to a line bisecting the angle between surfaces 20 and 40 or surfaces 22 and 42. This cross-sectional dimension roughly indicates the amount of material wh~ h must be compressed for the closure member to be pulled through the opening in the retaining device 24. As the cross-section continues to increase, the resistance to extraction increases in spite of the ductility or flexibility of the heat-recoverable closure material.
In assembling the retaining device 24 about the edges 12 and 14 of the closure member 10, a tool having guide rollers may be employed. A suitable tool is illustrated by way of 2S example in Figures 1 and 5 and includes a support member 48 and guide rollers 50and52rotatably mounted on the support member. The guide rollers 50 and 52 define a passageway therebetween which :: - 14 -.. ... :

approximately conforms to the desired final configuration of the retaining device 24. Mechànical leverage may be conventionally applied where high force~ are required for closure of the legs 32 and 34. The closure of the legs 32 and 34 around the wedge~shaped ridges accommodates variation in the edges 12 and 14 when the retaining member 24 is deformed.
Thu9, close tolerances on the closure member 10 and the retaining device 24 are not required. The ability of the assembly to tolexate dimensional anomalies in the component parts may also be enhanced by heat-recovery of the edges held within the retaining device 24. On ~uch heat-recovery, the edges tend to shorten and thicken to fill the wedge-shaped cavity formed.
Referring now to Figure 6, a construction is illustrated for the elongate parallel ridges 16 and 18: Figure 6 illustrates the use of interlocking means for preventing sliding movement between edges 12 and 14. In the embodiment shown in Figure 6, longitudinal channels 54 and 56 are provided respectively in the flat mating surfaces 20 and 22. These channelc 54 and 56 form an elongate cavity in which a rod may be positioned to further insure the integrity of the clo~ure. The mating surfaces 20 and 22 may also, or alternatively, be serrated to prevent longitudinal movement of one edge relative to the other.
Two further embodiments of the present invention are illustrated in Figures 8 to 11. In these embodiments, greater reliance is placed on the use of the heat-recovery properties of the closure material in obtaining a ~trong seal. In Figures 105~7 8 and ~, an embodiment is shown which inc]udes ridq~3 58 and 50 which do not closely c~nform to the inner ~hape ~f the retaining device 62. Mating surfaces are provided between rid~es 58 and 60 to create a proper seal once the closure i~
fully assembled. A retaining device 62 may be positioned o~er ridges 58 and 60 and then crimped in order tightly to hold the closure member or may be preformed to approximately the width of the closure member just below the adjacent ridges 58 and 60 in which case the retaining device 62 would be slid from one end around the ridges 58 and 60. In any event the legs of the retaining device 62 converge to create a modified channel allowing some opening for receiving the connecting portions between the edges and the main body of the closure member 10.
The positioning of the retaining device 6~ is facilitated by the non-conformity of the ridges 58 and 60 wit~ the inner shape of the retaining device 62.
Once the retaining device 62 is positioned over ridges 58 and 60 heat is applied either specifically to the ridges 58 and 60 or to the entire closure member 10 in order that the dimensionally unstable heat-recoverable material may be recovered. The closure member 10 is preferably such that its width will diminish upon recovery so that the closure member fits tightly around an enclosed article. With the contraction of the closure member the thickness of the material expands.
This is equally true at the edges where ridges 58 and 60 tend to become thicker as can be seen in Figure 9.
Thus the ridges 58 and 60 will tend to achieve a wedge-shape upon recoYery due to the wedge-shape of the 10519~7 inner ~urface of the formed retaining device 62. When the temperature of the recovered material is again lowered below the range in which it is dime~ionally unstable, relatively hard wedge-shaped ridges are formed which cannot be easily withdrawn from the retaining device.
Another embodiment of the pre~ent invention is illustrated in Figure~ 10 and 11 In this embodiment, no ridges are provided whatsoever along edges 64 and 66 on closure member 10 before heat-recovery of that member. When no ridges are provided, placement and retraction of the edges 64 and 66 before heat-recovery of the closure member 10 are relatively easy The retaining device 68 used in this embodiment of the invention is preferably shaped such that some retaining force is provided to hold edges 64 and 66 when the closure member 10 lS is inserted therein. Thuq, edges 64 and 66 may be brought together around an article to be enclosed and then forced into the retaining device 68 where they are lightly held until heat it applied.
Again, the char~cteristic expansion in thickness with a contraction in width obtained on heating will cause ridges~
to form on the edges 64 and 66. These ridges will be no gre~ter in width than the main body of the closure 10 provided that the closure 10 is allowed to recover substantially completely. The retaining device 68 will prevent recovery at the point where the converging legq of the retaining device terminate such that the ridges formed will be separated from the equally thick main body of the closure member 10.
In order to prevent the closure member 10 being extracted .,, 10519~7 from the retaining device 68 during recovery and before the ridges have been formed on the edges, the edges 64 and 66 are preferably heated prior to the heating of the main closure member 10 (although such prior heating may be avoided if the retaining device 68 grips the edge~ 64 and 66 80 firmly that no extraction iq possible). This prior heating may be accomplished, for example, by heating the retaining device which in turn raises the temperature of the edges to a heat-recovery level.
Consequently, no tension through heat recovery is established in the closure member until after the edges 64 and 66 have had an opportunity to expand and become locked within the retaining device 68. Again, a rigid, tightly fitting structure is formed by edges 64 and 66 which provides a tight seal not easily extracted from the retaining device 68.
It is not nece-qsary that a wedge-qhaped cavity be provided by the retaining device. Any one of a wide variety of cavitie~
may be employed. A cylindrical cavity 70 is illustrated in Figures 12 and 13. However, as with the wedge-shaped cavity and the cylindrical cavity, it i9 greatly advantageous to employ a configuration which includes legs that converge to a relatively narrow opening through which the closure member may extend. The combination of such a retaining device having converging legs and a closure member with heat-recoverable edges results in the various advantages mentioned above in connection with the present invention.
The cylindrical shape of the retaining device 72 sh~wn in Figures 12 and 13 has been proposed for earlier closure assemblies. However, such closures required that the fi~
between the retaining device and the 10519~7 bead formed by the contiguous ridges be as ti~ht as po~sible to form a proper ~eal. The tightness of such assemblie~ wa~
compromised by the difficulty encountered in assembling such clo-~ures. ~he fit selected for such assemblies was necessarily too tight for easy assembly and too loose for an ideal seal.
Furthermore, clo~e tolerance were required in the fabrication of parts if this less-than-ideal fit was to result in an acceptable product.
In the present invention, the bead formed by the closure member ridges 74 and 76 illustrated in Fi~ure 12 i~ substantially smaller than the space enclosed by the cylindrical retaining device 72. Consequently, the cylindrical retaining device 72 may be easily slipped over the undersized bead. Once assembled, the bead may be heated to the heat-recovery temperature which lS allows ridges 74 and 76 to expand and become securely held within the retaining device 72. Thus, the closure is easily assembled and may still form an excellent seal.
In the embodiment of the invention shown in Figure~ 12 and 13, it is possible to distort the edges of the closure member such that the bead formed on recovery will more than fill the cylindrical cavity. Thus, on recovery, the closure member will completely fill the space available to it and conform to the whole interior surface of the retaining device, achieving optimum integrity for the closure.
2S Thus the invention makes it possible to provide a heat-recoverable closure assembly which incorporatea a joint assembly that can be t~ghtened by the shrinking of the closure member.

Further, the advantageous forming of the retaining device insures closure of the joint and accommodates wide anomalies in either the closure ~tructure of the retaining device.
While embodiments and applications of this invention have been S shown and de~cribed, it should be apparent t~ those skilled in the art that many more modifications are possible without departing from the inventive concepts herein described.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A closure assembly which comprises a closure member comprising dimensionally heat-unstable material, the closure member having two opposite edge regions that can be brought into abutting relationship with each other, and fastening means for receiving at least a part of the edge region and maintaining them in abutting relationship during recovery of the closure member, the edge regions and the fastening means being such that, before installation of the assembly and recovery of the member the fastening means may be positioned over the abutting edge regions, the space defined by the fastening means having a shape or dimension differing from that of the abutting edge regions and such that, during installation and recovery, the dimensions of the fastening means, of the abutting edge regions, or of both the fastening means and the abutting regions, are changeable to cause their shapes to conform more closely to each other.

2. A closure assembly as claimed in claim 1, wherein each edge region comprises an outwardly extending wedge-shaped ridge having one surface for mating with a surface of the other edge region.

3. A closure assembly as claimed in claim 1 wherein each wedge-shaped ridge comprises first and second surfaces disposed at about 45° to the mating surface of the edge region which includes that ridge.

4. A closure assembly as claimed in claim 3, wherein the fastening means comprises a central portion for contacting the first surface of each of the ridges and two side portions, each of the side portions being such that it can be deformed during installation to contact the second surface of a ridge.

5. A modification of a closure assembly as claimed in claim 1, wherein before installation of the assembly the fastening means is such that the space defined by it conforms closely to the shape of the abutting edge regions.

6. A closure assembly as claimed in claim 1, wherein the mating surfaces comprise means for reducing sliding of one mating surface relative to the other.

7. An assembly as claimed in claim 6, wherein the means for reducing sliding comprise interlocking or inter-engaging means.

8. An assembly as claimed in claim 1, wherein the surface of the member, the surface of the fastening means, or of both the member and the fastening means are provided with an adhesive or a sealant.

9. A closure assembly as claimed in claim 1, wherein the edge regions are dimensionally heat-unstable.

10. A closure assembly as claimed in claim 1, wherein the edge regions are capable of increasing in thickness on the application of heat.

11. A closure assembly as claimed in claim 1, in which the edge regions recover to become wedge-shaped, or to increase the angle of the wedge, on application of heat.

12. A closure assembly as claimed in any one of claims 9, 10, or 11, wherein the edge regions are capable of forming ridges when they are retained in abutting relationship and heated to cause recovery thereof.

13. A closure assembly as claimed in claim 1, wherein, before installation, the thickness of the edge regions is substantially equal to the thickness of the remainder of the closure member.

14. A closure assembly as claimed in claim 1, wherein the closure member comprises a plurality of sheets of dimensionally heat-unstable material, each of the sheets having two edge regions each of which can be brought into abutting relationship with an edge region of another sheet.

15. A heat-recoverable closure assembly comprising an elongate closure member of dimensionally heat-unstable material, the closure member extending to edge regions capable of being brought into mutually contiguous relation-ship, at least the extremities of the edge regions having the property of dimensional heat-instability resulting in an increase in thickness upon heat-recovery, and fastening means for co-operating with the edge regions to retain the edge regions in contiguous relationship during heat-recovery of the closure member, the fastening means defining a channel including converging legs capable of engaging the closure member to contain the contiguously arranged edge regions.

16. A heat-recoverable closure assembly comprising an elongate closure member of dimensionally heat-unstable material, the closure member extending to two edge regions capable of being brought into contiguous relationship, the closure member including a mating surface and an outwardly extending wedge-shaped ridge extending along each of the edge regions, each ridge being defined by two surfaces disposed at about 45° relative to the respective mating surface, and a retaining device for cooperating with the outwardly extending wedge-shaped ridges to retain the mating surfaces in contiguous relationship during heat-recovery of the closure member, the retaining device being capable of being positioned over the wedge shaped ridges such that the converging legs engage the wedge shaped ridges preventing extraction of the closure member from the retaining device.

17. retaining device for joining two elongate mutually contiguous edges in a heat-recoverable closure assembly, comprising an elongate channel member having a pair of interconnected webs having straight portions which are parallel or convergent, the ends of the portions remote from the interconnection between the webs having short outwardly extending terminal flanges, the channel member being deformable by force to bring the said ends into pinching relationship and being such that on release of the force the ends remain in pinching relationship.

18. A method of joining two opposite edges of a closure member comprising dimensionally heat-unstable material, which comprises bringing the edge regions into abutting relationship with each other, positioning fastening means to receive at least portions of the edge regions, and heating the edge regions whereby they change in dimensions to conform more closely to the dimension of the space defined by the fastening means.

19. A method as claimed in claim 18, wherein the edges of the closure member expand in width on heating.

20. A method as claimed in claim 18, wherein the fastening means comprises converging legs and the legs are crimped, before or after the fastening means is positioned to receive the edges, to engage the edges and to form a wedge-shaped cavity between the legs.

21. A method as claimed in claim 18, wherein the closure member is heated to cause recovery thereof.

22. A method as claimed in claim 21, wherein recovery of the closure member is effected after at least partial recovery of the edge regions thereof.

23. A method for joining elongate mutually contiguous edge regions for a heat-recoverable closure assembly including the steps of placing two edge regions of a closure assembly in mutually contiguous orientations, placing a channel member over the mutually contiguous edges, the channel member having converging legs, and heating the edge regions of the heat-recoverable closure assembly to bring about their recovery such that the mutually contiguous edges expand in width to conform to the inner shape of the channel between the converging legs.