Note: Descriptions are shown in the official language in which they were submitted.
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1 UNITED STATES PATENT APPLICATION
3 RECOVERA~LE SLEEVE ASSEMB~Y
4 The present invention is directed to a recoverable sleeve
assembly that can be applied without heat or a solvent. ~eat
6 shrinkable sleeves with or without internally coated sealant
7 have found wide utility for insulating conductors in a splice.
8 1 A major disadvantaye is the necessity of a heat source to
9 ¦accomplish th~ ~Gcovery. The heat source may be an open flame
10 ¦ or hot air gun, both of which provide a hazard in an atmosphere
11 ¦ where combustible gas may exist such as in a coal mine or man-
12 1 hole.
13 U. S. Patent 4,035,534, to Nyberg discloses a heat
14 1 shrinkable member formed around and held by adhesive or
15 ¦ coupling agent to an elastomeric material. ~he heat shrinkable
16¦ member is disclosed as a heat recoverable thermoplastic material
~71 having sufficient rigidity at storage temperatures to hold the
18¦ elastomeric material in the desired stretched position. U. S.
~91 Patent 3,243,2ll to Wetmore discloses a sleeve ass~mbly co~- _
201 prising a rigid fusible tubular member surrounding a recoverable
21 tubular member and holding the recoverable member in expanded
221 condition under tension. The fusable me~nber is describcd as
231 ~irtually any material capable of being rendered flowable by
24 the application of heat such as thermoplastic materials as
well as thermosetting materials.
26 ~ number of methods Eor recovering an elastomeric sleeve
27 without the usq of heat have been proposed and some of these
28 are in a~tual use. ArtlcleF3 and methodc; emyloying both .
29 in~ernal support mombers and cxternal support members have be~!n
designed~ Methods with internal support members are discloscd
31 in U. S. ratonts 2,725~62l ~o G~tes alld 3,515~798 to Sievert.
32 Thc Gates patent discloscs the use o a sloove o~ Era~yiblc
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1 ¦material holding an elastic sleeve or tube in stretched
2 ¦ condition so that an impact to the assembly disintergrates
3 ~ the inner sleeve allowing the elastomeric portion to collapse
4 1 and shrink. The Sievert patent discloses an elastic cove~
5 ¦ with an internal support core which can be removed by spirally
6 1 unwinding; such an article is in wide spread use. Internal
7 ~ support techniques have two major aisadvantages. No sealant
8 1 or adhesive can be applied to the inner surface to aid in
91 bonding the shrinkable member to a substrate such as a cable, -
and the internal support is often difficult to remove over
111 an irregular substrate.
12¦ Several shrinkable elastomeric tubes have been designed
13¦ with external support means. U. S. Patents 3,770,876 to '
14¦ Post discloses external means provided to pre-stretch the
15¦ elastomeric tube at the time of installation. U. S. Patent
16 3,824,331 to Mixon et Rl discloses an elastic tubular member
17¦ rolled back on itself in storage condition on an external
; 18 support member and unrolled at the time of use. This con-
19¦ struction restricts the elastic member to a thin wall rubber _20 ¦ sleeve thus reducing the abrasive resistance of the resultant
21¦ cover. U. S. Patent 4,070,746 to Evans et al discloses an
22¦ external rigid restraint bonded to the outer surface of an
23 ¦ elastomeric member with the bond susceptible to attack by
241 solvents to allow the elastomeric sleeve to peel away from
2s1 the outer member upon the application of the solvent. British
26¦ Patent 1,556,677 discloses a recoverable article includinq
271 the ~eature~ o~ the Evans et al patent hut also disclosing
231 provislon ~or an outer restraining member capable o~ beinq .
291 sQgmented or broken by shattering, R typical restrainlng
301 mean~ is disclosed a~ a thqLmoplastic such a~ polyvinyl
3~1 chloride, U. S, Patent 4,l79,320 to Midgley disaloses a re-
32 Govcrabla ar~icle having an elastomeric mamber hqld ln
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s-tretched condi-tion by a flexible ou-ter reS-traininCJ
means provicled with score lines.
The presen-t invention resides in a recoverable
sleeve assembly includingan inner elas-tome,ric tube and an
ou-ter rigid tube surrounding and secured to the inner tube
and ho"Lding -the inner tube in outwardly stretched condition.
The outer tube extends axially beyond and covers at least
one end of the inner tube and is secured to the end of
the inner tube.
A specific embodiment of the invention provides
a recoverable sleeve assembly wherein an inner elastomeric
tube is held in expanded condition by a rigid thermose-tting
polyuret'hane outer tube which is secured to a pre-stretched
elastomeric inner tube. The recoverable sleeve assembly
combines the two essen-tial features of rigidity and optimum
peel strength in a single unit. The outer supporting tube
can be removed at the time of recovery without the use of
any solvent to break the adhesive bond. The outer tube is
a rigid thermose-ttiny polyure-thane adhesive made from a polyol
reacted with an isocyanate in a formula-tion to provide a
decJree of adhesion which has suEEicient adhesive strenyth
in tension to hold -the inner tube stre-kched but is weak enouyh
in peel to allow the riyid sleeve to be r~moved after
breakiny by impact or application of hea-t without the use of
a solven-t.
The preEerred thermose-tting adhesive is a po:lyes-ter
po:lyo:l Eormed Erom a m1xture oE tr:imethy:Lol propane brancilecl
glycol, ad:ip~-te polyo:L or polycaprolac-tone polyol mocliEied
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with 1,4 butanediol reacted with the isocyana-te.
In a specific embodimen-t -the outer -tube has a
thickness equal to the to-tal thickness of the inner tube
plus the -thickness of that portion of -the outer tube which
surrounds the inner tube and preferably the outer tube
extends axially beyond and covers and is secured to both
ends of the inner tube.
Other features and advantages of the present
invention will become more apparent upon perusal of the
following specification taken in conjunction with the
accompanying drawings wherein similar characters o~
reference refer to similar elements in each oE the several
views.
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1 DESCRIPTION OF THE DRAWINGS
3 Figure 1 is a perspective view partially broken away of
4 one recoverable sleeve in accordance with the present inventio~O
Figure 2 is a elevational view, partially in section,
6 of a portion of the structure shown in Figure 1 taken along
7 line 2-~ in the direction of the arrows.
8 Figure 3 is a elevational sectional view of a recoverable
sleeve asser~ly in accordance with the present invention for
insertion over a substrate.
11 Figure 4 is an enlarged sectional view of that portion of
12 the structure shown in Figure 3 deiineated by the line 4-4,
13 Figures 5, 6 and 7 illustrate one manner in which the
1 xecoverable sleeve is utilized in practice.
1 Figures 8 and 9, 10 and 11, and 12 and 13 illustrate other
16 manners of use of the present invention.
17 Figure 14 is a side elevational view, partially in section,
18 schematically illustrating certain of the steps in forming
19 a recoverable sleeve in accordance with the present invention. _
Figure lS is an elevational sectional view of a molding
21 step utilized in forming the recoverable sleeve assembly in
22 accordance with the present invention.
23 Figure 16 illustrates a recoverable sleeve assembly formed
24 in accordance with the molding step illustrated in Figure 15.
Fiyures 17 and 18 are flgures similar to Figures 15 and
26 16 illustrated in another embodiment of the present invention.
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DESCRIPTION OF PRFFERR~D EMBODIMENT
2 Referring now to the drawing with pa~ticular reference to
3 Pigures 1 - 3, there is illustrated a preferred embodiment of
4 the recoverable sleeve assembly in accordance with the present
invention. The sleeve assembly 10 includes an inner elastomeri~
6 tube 11 in outwardly stretched condition and an outer rigid
7 tube member 12 surrounding and secured to the inner tube 11 and
8 holding the inner tube in its out~ardly stretched condition.
9 The outer tube 12 includes a central portion 1~ surrounding and
secured to the outer surface of the inner tube 10 and two end
11 portions 14 and 15 extending axially beyond the ends lla and llb
12 o~ the inner tube and secured to the ends lla and llb of the
13 inner tube. The end portion~ 14 and 15 have a thickness equal
14 to the total thic~ness of the inner tube plus the thickness of
the central portion 13 of the outer tube which surrounds the
16 inner tube 11.
17 The end portions 14 and 15 serve several different purposes.
18 They provide a strong support ring at the end of the assembly
19 which is thicker and stronger in the radial direction than the _
20 central portion 13 of the outer tube. They cover and are secured
21 to the end of the inner tube 11 preventing access to the inter-
22 face between the outside surface of the tubular member 11 and the
23 central portion 13 of the outer me~ber where peeling ,apart
24 of the inner and outer tubular members 11 and 12 begins.
25 Additionally they serve to shield the intarace between the
26 inner and outer tubular member~ 11 and 12 at the end of the
27 tubular member 11 from engagement by the end of a substrate 16
2a such as a c~ble onto which the recoverablc sleeve i~ tele~copi- .
2 cally moved SUCII as for coverincJ a splJca or the like, Contao~
3 between the ~ubstrate 16 and either the interPace or tho end ~f
3 tha innor t:ube 11 can causo the tubes 11 and 12 to becJirl to
3 pcel apart~ --
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1 ¦ The inner tubular member is preferably a rubber elastomerie
2 ¦sleeve. The major property requirement of the elastomerie
3 ¦sleeve or tube 11 is that it must have low permanent set when
4 ¦stretched such as approximately 100 to 150% radially. This i3
¦required since in the end produet the elastomeric tube 11 will
6 ¦be held in expanded condition for extended period of time during
7 Istorage. A preferred material for the inner tube 11 is a
8 ¦neoprene rubber formulation which has necessary recovery - _ .
9 ¦properties with flame retardance, particularly suitable for
10¦ splicing coal mining cable. Typical mechanical properties ~or
11 ¦this formulation are tensile strength of 1800 psi, elongation
12 ¦of 400~ and 100% modulus of 430 p~i.
13 ¦ The preferred outer tube 12 is a rigid thermosetting
14¦ adhesive comprising a polyurethane formed of a mixture of a polyol
15 ¦preferably polyester polyol such as TMP (trimethylol propane)
16 ¦bra~ched glycol adipate or polycaprolactone polyol modified with 1
17 ¦4 butanedi~l reacted with an isocyanate. The trimethylol propane
18 ¦branched glycol adipate preferred is a hydroxyl terrninated
19 ¦polyester in the lecular weight range of 1000-2000 which _
20 can be prepared from dibasic acids such as adipic and se~aeie
21 reacted with an excess glycol (ethyleneglycol or diethylene
22¦ glycol) or polyhydric alcohol such as glycerol or trimethylol
23 ¦ propane. Reaction with a slight excess of glycol insures that
24 ¦ the polyester will be hydroxyl terminated. These hydroxyl
25 ¦ groups are available to participate in the urethane reaction.
26 ¦ A pxeferr~d formulation is as ~ollows:
27 ¦ FO~ULATION I
28 Parts
I ~r---P branch~d,~lycol adipate~FORMREZ 102, .
29 I Wi~co Che~nieal)
15 1~ 4 b~tanediol ~BASF)
30 ¦ 3 Phenylrnercurie propionate aatalyst
I ~ T~SOI. 57, ~erck)
81 1 antio~idant ~ c~ol ll Monsanto)
32 ¦ 1 releas~ ~In~ -20~ Axel Pl~5tlcs)
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1 101 parts of the above ~olyester polyol were reacted with
2 ¦115 parts of a polymeric ~socyanate such as Rubinate-M by
3 ¦Rubicon Cl-emicals to produce a composition having a tensile
4 ¦modulus of 363,000 psi. Other isocyanates such as PAPI 135 by
5 ¦ ~pjohn and MONDVR MR by Mobay Chemicals can be used.
6 ¦ The polymeric isocyanatPs or diisocyanates when reacted
7¦ with the polyol in the presence of a catalyst react rapidly to
8¦ form a polyurethane. The ratio of the isocyanat:e to the polyol
9¦ mixture should be in the range of 1.05 to 1.10 equivants of
10¦ isocyanate per eguivalent ~eight of polyol. A unique feature
111 f the polyurethanes used in this invention is that they can be
12¦ mixed in a high intensity mixing head and injected into a mold
13¦ while still liquid and within a few minutes cure to a solid
14¦ thermoset resin.
15 ¦ Other formulations can be based on polycaprolactone polyols
16 ¦ modified with l, 4 butanediol and reacted with an isocyanate.
17 The exact modulus of the outer shell is difficult to define since
18 ~he ability to hold the rubber sleeve expanded without collapsing
19 is a function both of the modulus and the thickness of the outer _
shell. For example, both of the following polyol formulations
21 reacted with isocyanate (PAPI 135 by Vpjohn), will function in
22 this invention.
23 . FO~UI.ATION II
Parts
24 65 polycaprolactone polyol (NIAX polyol PCP 0300,
Vnion Carbide)
20 polycaprolactone polyol ~NIAX polyol PCP 0200,
Union Carbide)
26 15 l/ 4 butanediol (BASF)
27 100 parts of the above polyol were reacted with 100 parts
23 of PAPI 135 to produce a composition having a tcnsile modulus
o~ 210,000 p~i.
29 FORMU~CO~ III
Part~
~~~~lycaprvlactone polyol ~ X pol,yol PCP 0300,
Vnion Carbidc)
31 15 1~ 4 butanediol ~ASF)
32 100 parts o~ thls ~ormul.ltion reactod with llS part:s o~ PAPI
~ 135 p~oduc ~ ~ompo:~tlon h~vlng a tonsll~ mo~l~luo of 317~00d P~
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1 Obviously For~nulation III can be used in a thinner cross- ~:
2 section to resist the collapsing force of an expanded rubber
3 tube. Howe~er, all forrnulations are effective.
4 In the present invention a thickness of 0.040-0.130 inch
is preferred for the ou~er mernber for an unexpanded neoprene
6 rubber inner tube .140 inches thick and ID of .85 inches which
7 is then stretched to an ID of 1.85 inches.
8 Other polyols which may be substituted for the polyols in
9 the above forrnulations to produce the rigid outec tube of the
sleeve assernbly are-polyester polyols such as ~ y~1
11 p~v~e-g~yeo-~ a~*e~-and poly neopentyl adipate and polyether ~,
12 polyols such as polyethylene glycol, polypropylene glycol,
13 alithatic hydroxy terrninated polyester and polypropylene
14 derivitives of propylene glycol, trimethylolpropane ~r sucrose.
A typical application of the recoverable sleeve assembly
lb 10 is illustrated in Figures 5, 6 and 7. ~he recoverable
17 sleeve assernbly 10 is placed on the substrate 16 and rested on
18 a flat surface. By stamping on the recoverable sleeve assembly
19 10 and allowing the assernbly to set for 30 second the inner
20 tube 11 will break free of the fragrnents of the outer tube 12 _
21 and shrink around the substrate 16. The outer shell fragments
22 are peeled away. Flexing of the splice as illustrated in
23 E'igure 1~ will help to remove the fragrnents of the outer tube
24 in any area where the inner tube has not been cornpletely
released~
26 Other techniques of utili2ation are illustrate~ in Figures
27 8 - 13. In Figures 8 and 9 utilization of the recoverable
23 sleevq assarnbly 10 is illustratcd by fir-;t fractur;ng such as .
29 ~7ith ha~MneL Il at only one erl~l of the assemhly 10 whereby the
~ inner tube 11 begins to peel aw~ly from the o-lter tmbe 12 and
3l then peels away successively longitudina]ly of the two members.
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1 ¦The remainder of the outer tube 12' can then be removed by
2 ¦frac~uring at the location or elsewhere after movement
3 ¦longitudinally o$ the substrate 16.
4¦ The present invention can be utilized without heat, but
¦ Figures 10 and 11 illustrate that heat can be applied to the
6 ¦ assembly 10 adjacent the joinder of the end of the inner tube
7 ¦ 11 to the end portions of the outer tube 12. The bond between
8 1 the inner tube 11 and outer tube 12 will be weakened and the :
9¦ end of the inner tube 11 will release and shrink peeling away
10¦ successively longitudinally from the outer tube 12. The outer
; 11¦ tube 12 can then be r~moved such as in the manner described
12¦ with reference to Figures 8 and 9
13¦ Figures 12 and 13 illustrate an alternative embodiment of
14 the present invention wherein the outer tube 12 " extends .
15 ¦ axially beyond and covers only one end of the inner tube 11.
16 ¦ In this embodiment when the substrate 16 is inserted into the
- 17 ¦ assembly through the end.where the outer tube projects beyond
18 ¦ the inner tube, the extending end portion of the outer ~ube 12''
; 19¦ protects engagement of the substrate with the end of the inner _
20 ¦ tube that could cause the inner tube to begin to peel away from
21 ¦ the outer tube.
.~ 22 ¦ The polyurethane shell can be molded in a relatively short
23¦ cycle. Referring now to Figures 14 - 16 t`here is illustrated
2~1 ~ preferred molding operation. In Figure 14 the .inner tube
25 ¦ 21 in unexpanded condition is providad over the outside of a
26 ¦ first, hollow cylinclrical, small diameter mandrel 22 one end of
27¦ which is connected to an air supply and the other end of which
28¦ is fittad into the small diameter end of a tapered mandrel 23.
29 ¦~'apered m~ndrel.23 is pr~vided with a aentral bore 24 which .
30 ¦communicatcs with ~.ha cen~ral hore 25 o~ mandrel 22. Passageways . ..
31 ¦2G axtend from tha taperad mandrel central bore 2~ to th~ 1.
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1 outside surface thereof terminating in ports 270 The large
2 ¦diameter end of the mandrel 23 fits on a small diameter
3 ¦cylindical end extension 31 of a matching larg~ diameter
4 ¦mandrel 32. The other end of the large diameter mandrel 32
is provided with a similar cylindrical end extension 33 which
6 ¦isconnected to an airsource for passing air through a central
7I axial bore 34 and radial passages 35 to ports 36 in the
8 ¦exterior surface of the mandrel 32. The elastomeric tube 21 . . . .
9¦ is slid longitudinally from the small mandrel 22 over the _-
10 ¦ tapered mandrel 23 onto the outside surface of large diameter
11¦ mandrel 32 whose diameter is equal to the desired expanded
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12¦ diameter o the inner tube 11 of the recoverable sleeve assembly.
13 ¦ Mandrel 32 is disconnected from the air supply and from
14 tapered mandrel 23 and with the stretched rubber sleeve 21' .
15 ¦ acts as the central core in a mold.i}lustrated in Figure 15.
16 ¦ The mold consists of lower and upper halves 41 and 42 each of
17 ¦ which have semi-cylindrical cavities which when the parts are
13 ¦ assembled provide a hollo~ cylindrical cavity having a diameter
19 ¦ equal to the desired out side diameter of the outer tube 12 of
20 ¦ the assembly. The mold halves 41 and 42 contain semi-cylindrical _
21 recesses ~or receiving the small diamater cylindrical and
22 ¦ extensions 31 and 33 of the mandre.l 32. The mandrel ~2 with
23 ¦ the attached elastomeric tube 21' is placed in the lower hal~
24 41 of the mold and the mold closed and the above mentioned
25 ¦ polyol~isocyanate mixture injected .into the mold around the
26 ¦ central core. The clearance between the outside surface of
27 ¦ the elastomeric tube ,21' of the central core and ths mold
23 ~avi~y is the wall ~:hickness o~ the outer tube 12 that surrounds .
29 ¦ thq inn~r tubq 11. It ls noted that the cavity ~3 Oe tllq
30 ¦ mold 1~ th~ full length o~ the mandr~l 32 ~hereas thq expandqd
31 elastomeric s].eevs is of lesser length and spaced :erom the ends
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1 ¦of the cavity 43. The material forming the outer tube will fill
2 ¦the space between the e~ds of the expanded tube 21 and the
3 ¦qnds of the mold cavity 43. The mold is heated to accelerata
4¦ the cure of the urethane. After about 10 to 15 minutes the
5¦ mold i5 opened and the core removed. After post-cure, the
6¦ composite rubber sleeve and polyurethane outer shell are blown
7 ~ off the rnandrel 32 by prsssuring the inside of the mandrel.
8 ¦ Prior ~o insertion of the mandrel 23 and expanded tube
9 21' into the mold, the outer surface of the sleeve 21' is
10¦ cleaned with a suitable solvent and treated with a release
11¦ agent to control the degree of adhesion of the outer urethane
12¦ jacket. Release agent~ such as zinc sterate, fluorocarbon basPd ~*~
13 releases or silicones such as RAM 225 by Ram Chemicals are
14 ¦suitable.
While the preferred recoverable sleeve asse~bly in
16 ¦ accordance with the present invention includes end portions of
17 ¦the outer member extending beyond both ends of the inner member,
18 an end extension of the outer ~ember can be provided on only
19 ¦one end of the inner member or on neither of the ends. _
20 ¦ Figs. 17 and 18 illustrate the molding method for providing
21 ¦ an assembly with an outer member extension on only one end.
22 ¦ As illustrated there the expanded tubular member 21'' is
23 ¦ positioned on thq mandr~l 23 with one end of the tubular member
24 all the way at the end of the larger diameter portion of the
25 mandrel 32 leavlng space between the opposite end of the tubular
26 member 21~' and the end of the hollow cavity 43 of the mold.
27 When the urethane mi~ture is injected into the mold cavity an
28 end yortion oP the outer rnember will project beyond only one
29 Qnd oP ~he inno~r mqmbcr. ~1hen the 40re m~mber ls removed from
3~ thq rnold~ ~he r~40ver~ble sleevq as~Qmbly r~moved Prom the
31 mandr~l will app~ar as in ~iCJure 18.
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