Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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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1051987
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
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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.
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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
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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
.
1051987
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
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1051987
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
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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
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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
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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.
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1051987
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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