CA1079327A

CA1079327A - Composite connector

Info

Publication number: CA1079327A
Application number: CA265,775A
Authority: CA
Inventors: Robin J. T. Clabburn; Frederick W. L. Hill
Original assignee: Raychem Corp
Current assignee: Raychem Corp
Priority date: 1975-11-17
Filing date: 1976-11-16
Publication date: 1980-06-10
Also published as: DE2652418A1; GB1573096A; FR2331738A1; US4424991A; JPS5287564A; US4309807A

Abstract

ABSTRACT

The substantial change in modulus with temperature of certain materials, especially memory metals, is used to make a novel connector by forcing a band made from such a material in its low modulus state up an external tapered portion of a tubular coupling member so as to deform the band which remains in position about the coupling member. To make a connection one or more substrates is(are) positioned inside the tubular coupling member and the band is brought to its high modulus state whereupon it contracts and deforms the tubular coupling member and forces it into firm connection with the substrate.

Description

BACICGRO~D TO ~ ~ INVENTION
q~i~ inventlon relate~ to connector~, e~pecially coupling member~ for ~ub~trate~ such ~ pipeQ~
The pipe~ u~ed in centxal heating ~ystem~ are generally coupled by traditional methods such a~ brazing. Similar method~ are al,80 employed in, Por example, the coupling o~ larger pipe~ ~uch a~
tho~e used for desert irrigation. Apar~ from obvious di~advantage~, ~uch as the t~me required to make each connectlon, the neea ~or skilled operator~ and the need to provide ~uitable equipment at the area of:~peration, the~e method~ have the further disad~an~age of placing a limitation on the choice o~ material used for the pipes. For example, brazing cannot be sati~actory employe~ with aluminium pipe~. .
It ha~ keen proposed ko maXe coupling memkers from heat-recoverable material3. For example, ~S. Patent ~o. 3,315,9~6 . .
propo~as the use sf heat-~hrinkable pla~tics material~ in the coupling of hose pipe~ and Bri~i~h Paten~ No~ 1,327t441 prOpO~e5 tha u~e o~ haa~-shrinka~le, internally toothed, ma~al cou~ling members for ~e connection of hydraulic pipe~ ~owever, unless ~pecial measures are take~, the connec~on~ obta~ned with heat ~hrinkable plastics mat rials are, in general~ unable to w~thstand ~igh i~texnal pres.ure~ and cannot reliably provide a long term : ~ Aeal against the eyxe~ o~, for exampl~ quid~ :~lowing through the.pipes, and the alloys u~ed in the heat-shr~nkable metal coupling 25 ~ bers are too e~pen~ive to warrant their usa in anytbing bu~
pecialised appli~atic>nsO
~: BRIEF S~ARY OF q~E ~VE~I~
he presen1: invention provlde~ a method of making a connec~or which compri~e~ the ~teps of:

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(a) providing a tubular member at least a portion of which has a tapered outer surface;
(b) providing at least one band made from a material which exhibits a relatively low modulus of elasticity at a first temperature and a relatively high modulus of elasticity at a second temperature; and (c) positioning said band about the narrower end of the tapered surface of the tubular member and forcing said band at said first temperature along and against the taper so as to expand it, the relatively hlgh modulus of elasticity of the material of said band being such that when the band is brought to sald second temperature it will contract and deform the tubular member.
The present invention also provides a connector which comprises a tubular member, at least a portion of which has a tapered outer surface and positioned about said tubular member away from the narrower end of the taper, a band made from a memory material which exhibits a relatively low modulus of elasticity at a first temperature below the transition temperature of the memory material and a relatively high modulus of elasticity at a second temp- ;
erature above the transition temperature of the memory material, said band being capable of contracting and deforming the tubular member on being brought to said second temperature.

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qhe ~re,sen~ lnventlon al~o provl~e~ a me~hod o~ m~J~incJ a conn~ct.ion to at l~a~ one ~ubstrate which com~rl~e~ placin~
sa~d ~ub~trate within a connector a~ de~cribed a~ovQ and then brin~ing the band to the second tem$cr~tuxe 60 'chat it contracts an~ foxces the tubular member i~to ~irm connection wlth thc ~u~strateO
. The pxesent ~nvention ut:ilises the ~.iyni.ican~ chan~e in ~he modulus o cexta~n materials as the temperature is v~x7~d and u~es ~he relative change ~n the strength o~ ~ band mad~ ~rom ~uch a material so ~hat, on th~ one h2nd, lt ca~ b~ defo~ned b~
u~in~ the tape~ed outer surace o~ ~he tubular member a~ ~
mandrel when the material is in its 1O~J-rnOdU1US s~ate and yet 80 that it can, on the other hand, force and/or de~orm the ~ubular memb~r 50 as to ~orm a connection wi~h a ~u~trate po~itioned within sald memker when the m~terial is in it~ high-~odulus ~ate.
. In general it will be pxefexred for the material used ~o form ~he band to exhibit a substantial change in mo~ulus on passing ~hxou~h a trans~tlon tem~erature or throu~h a xelatively ~mall temperature ranye as this ena~le~ ~he connections to ~e maae more xapiæly ~nd also ensures that the ~trength of the ~onnection once made, will no~ alter ~igni~icantly so lo~g a~
the tempera~ure does not return to.the relevan~ transition tem~erat~xe (or ran~e~c . Amon~s~ ma ~rials sui~able ~or ma~ing th~ band ~ere may be ment~oned certain plas~ics ~at~x~al~, ~specially so-called ~engine~rlng ~las~ such a~ the polyarylenee ~old under the trade mark #Stilan" by Raych m CorporationO ~hese polyarylenes 4 ~o ... . . .
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are polymers consistlng predomlnantly of aryl, e.g. phenyl or substituted phenyl, groups which may be linked, for example, by direct linkages or by alkylene, carbonyl, sulphonyl or ether linkages or mixtures of the above linkages. Preferred polyarylenes are described in Belgian Patents Nos.
779,457; 779,458 and 779,459. These materials may have a highly crystalline nature and, even without cross-linking, can be deformed at room temperature and yet still have sufficient elastic memory to return to their original con-figuration UpOII heating. Alternatively, they may be deformed at an elevated temperature and then allowed to cool and contract. Other engineering plastlcs such as polyketones, polysulphones and polyphenylene sulphides may also be used. Conventional heat~recoverable plastics materials, e.g. cross-linked polyethylene may also be employed in certain applications.
However, especially suitable materials for use in the present invention are "memory metals". By a "memory metal" there ls herein meant a metallic material from which a heat recoverable article can be made, that is, an article which can be deformed from an original heat-stable configuration to a different heat-unstable configuration in which it will remain until raised above a temperature known as the transition temperature when it will return or attempt to return towards its original configuration. It will be understood that the heat-recoverable article is capable of returning towards its original configuration without the further application of outside force.
~nongst such memory metals there may especially be mentioned various :

' -. ~ ' ,, ., ', ' ' . !: ' :: ' ' ' ' ' ' ' 3~7 alloys oE titanium and nickel which are descr:Lbed, for example in U.S.
Patents Nos. 3,174,851, 3,351,~63, 3,753,700, 3,759,552, British Patents Nos.
1,327,441 and 1,327,4~2 and NASA Publication SP 110, "55-Nitinol-The Alloy with a Memory, etc." (U.S. Government Printing Office, Washington, D.C. 1972).
The property of heat-recoverability has not, however, been solely confined to such titanium-nickel alloys. Thus, for exarnple, various beta-brass alloys have been demonstrated to exhibit this property in, e.g. N. Nakanishi et al, Scripta Metallurgica 5, 433-440 (Pergamon Press 1971) and such materials may be doped to lower their transition temperatures to cryogenic regimes by known techniques. Similarly, 30~ stainless steels have been shown to en~oy such characteristic E. Enami et al, id at pp. 663~68.
In general these metals have a transition temperature within the range of from -196C to ~135C, especially from -196C to ~70C (this being the lowest temperature they are liable to encounter during everyday use), and thus may be brought into their martensitic state by immersion in liquid nitrogen. However more recently, it has been found possible to "precondition"
memory metals so as transiently to raise their transition temperature. This enables the articles made from such alloys to be kept at room temperature prior to use, when they can be recovered by heating. Such preconditioning methods, which eliminate the need for liquid nitrogen during storage and trans-portation, are described, for example, in German Offenlengungsschrift Nos.

2,603,278 and 2,603,911 published on August 18, 1976.

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The band made, for example, from the memory metal is preferably a continuous ring, but it should be appreciated that the band may be split and/
or may have a non-circular cross-section.
Similarly it should be appreciated that the terms "tubular member"
and "tube" as used herein are not limited s:imply to continuous tubes of circular cross-section, but are intended to cover tubes of other regular or irregular cross-sectional form as well as tubes which may exhibit discon-tinuities, i.e. which may be longitudinally or otherwise split, and me~bers of, for example, T-, Y- or X-shape. The terms are also used herein to include closed tubes, i.e. those having at least one end which is not open.
In the preferred forms of connector according to the present invention, the ends of the tubular member are externally tapered, preferably so that the narrower portion lies toward the open end of the tube and the wider portion is remote from the open end of the tube. In such embodiments the bands will be initially positioned at the open ends and will be pushed up towards the central portion of the tubular member to deform them. It may be advantageous to provide means at the central portion of the tubular member to ensure proper positioning of the bands after they have been forced up the taper and to prevent the bands from being pushed fur~her than desired.
Such means may, for example, be provided by a shoulder formed , : : i . : : . ,. . - , ; - . -: . : - , . ,: .. . . . , . . . .. : .:: ~ . . . . , : .

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on th~ externa~ ~urface o~ th~ tubular member. ~lte~natively a ~epar~te po~itior~ member may be provided which i~ it.c~elf positioned on th~ tubular member by engaging a groove and/or pxotubera.nce on th~ extern~l surface of t~e tubular melnker.
~n other embodLments of ~le present invention, the or each end of the tubular m~mber i~ tapered so that the narrow~r por~ion lie~ away fxom the open end~ In such emkodir~ent~ the band or bands ~zill initially be ~laced over the centra~ portion o~ th~
kubulax membex and will be ~orced up the kapered portion(s) toward~ th~3 open end~s). Aga~n, the tubular member i~ pxeî:^exa~
pxov~ded with means :~or proporl~ position.ing the band(s) a~ter de~ormation and, ~n ~his ca~et to preven~ the bandts) from beir~g forced o~ tlle end ( ~ ) of ~e mer~er.
q`he inner sur~ac~3 of the band may ~e c:on~oured~ e"y. may have one or more of lt~3 ed~es curved, 80 a~ to ~acîli~at~
movPment up the tal?er. For example t~e band may be :eormed a~ a xing of cir~ular cross; sectic)n thus enabling i~, ln some cases, to b~ rolled up the tape~, e . g . like an elastic l~and. In other embo~liment~ it may also be advanta0eous to provide the inner surface of the band and/or the outer ~u~face of the tubulax ~nem~er with screw th:r~ading lko as~ist mo~7~ment of the band up ~'che taper during expansion. In some cases it may ~l~o ~e ad~antageou~ to provide t~e inner sur~ace o~ ~he band and~or ~h~ outer ta,~ered surface of the ~u~ular membar with a 3ui~able lubricantO
-~he ~refexred angle Q~ the tapered portion(s~ will dep~n~ :
on the ~aterials e~plo~ed and the applica~ion concexned~ In ~ome cases, an~les o~ 30 and higher may ~e appropr~a~e, thus allowi~ ths :Len~tll o~ the connector to be kept ~mall~ IIowever, ~: ' , . . .
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~n g~neral, an~le2~ o~ not ~reatex than 5 will b~3 used, an~
of ~etween 1 and 2 b~inç~ e~3peciall~r ~u~table.
The maximum amount o~ thermally xecovexable dimensional deformation which can cuxxently ~e obtained with mPmoxy metal~
i8 abou~ 8~oO Up to a strain o~ about 8% the mem~ry r,letal de:Eoxms eaaily and the main ~orce~ encountered in moving a band up a tapered porl-ion aro ~rictional. Abo~e ~0 it becomes extremely dlfflcult further t~ de~orm the band of memoxy metal.
. ~hi~ ~act can be u~ed to advantat3e in the co~nectors of the pr~ent invention~ ~u~pose, for exc~mple that the widox ~nd o th~ tal?ered portion coxr~sponds to a deormation of 12% in th~3 band, then u~on forcin0 the barld up the ta~oex ~ w:~.ll easily e~?and up to about 8%, at which ~;taç~e~, it will hav~ roved along about ~3 o~ the taper. ~lhen ~u~ther ~orce is ap~lied to 1~ the band ~n an endeavour to ~oxce it up the tapex ~ the e~fect ta~s~nin~ th~t ~he tubular ~lember is made i:rom a relatively -~ soft material~ will ~e such that force will cause a crus'ning of the tubular me~er an~, possibly~ the substxa~e wi h lit~le o~ no ~urther expansion o~ ~e band. Thi.s crushin~ will ta~;e up any clearance ketween tne bore o~ the tu~ular m~nJDex and th~
~ub~trate and, possibly, will even sligh~ly crush th2 sub3trat2.
hu~, vlx~ually all of the 850 r~c:overy will s~ be avail~ble to produce an armular indentation in the u~s~rate upon heatin~
and the need or acc-ra~e ~lim6n~;ioning o:~ ~h~ connector in relation to the substrate, is, in such a case, conside~al~ly reduced~ ~nu~ it ;nay, in ~ome cases, be ad~anta~eou~3 to forn~
~: the tapered ~?ortion(~) o~ th~ tu:bular rn~nbex in such a way hat the band3 cannot ~e forced coTr~le~ely to ~he end oP the ,~ ~

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taperod port~on~, at lea~t without causlng ~om~ doforma~lon of the tubular m~mber ~t~el~.
It will be appaxent that t~e tubular mem~er must ~e mP.de from a material with suitable ~treng~h characteristic~ haviny xegard to the s~rength of the band o~, for exar~ple, the memory metal. ~us, in most el~bodiments of the present invention, the tu~ular mer,~ber must be made.~rom such a material that, and must be so constructed that, it will he ~ufficiently strong ~ ac~ a~ a mandrel and defo~ the ~and when t~e mater~al o~
the latter i5 in its low-rnodulus state and yet will itself be defo~tted wl~en the material assume~ it~ high-modulus st~te.
In this respec~ .~t may, in som~ cases, ke adv~ntageous to al~er the s~ructure of ~he tubular r,lember after th~ band(s) have been ~oxced u~ the tapered portions and deformed~. ~or exarr~le, an ini~i~lly ~hick-wall~d tubular couplin~ mem~er may ke bored ou~ af~er the b~nd~ ha~e keen ~oxced u~ e ~apered poxtion~ in~o position to produce a rela~ively thin-walled member which ~ill b3 de~ormed upon xeco~ery of th~
band~
~o It will in ~eneral ~e prefexred tha~ ~he connec~or i5 ~orr.l2d in a marmex~ such that i~ can ~ ~tor~d and ~ranspo.rted . prior to use. ~hi8 may be ach1e~ed, ~or example, in th case o~ m~moxy rnetals~ by forming, storing and tran~portin~ the connector ~n a suit~ coolant, e.g. liquid nitroyes~, or m:>re esp~cial~y by 'precondl~ioniny~ ~he memory metal a~ des~ribed ~:
aboveO ~u~, fc)r exain~?le, in one especi~lly pre:Eerred embodiment o~ ~he present. ~nvention~a connec~or i~ prepaxed as :f~ollot,Js: a ~; tubular mem'~r ln the ~o~n of a sirnple tuhe w:L~h t~o end portions which taper towards the open ends of the -tube is prepared having a smaller bore than that which will finally be required.
Two memory meta]. rings are positioned a-t each end of the tube and the assembly is cooled to below the transi~ion tempera-ture ~ the memory metal whereupon the rlngs are forced up the tapered portions towards a central position. The assembly is then allowed to warm above the transi-tion temperature of ~he memory metal ~hereupon the thick-walled tubu~ar member continued to act as a mandrel because its thick walls are too strong to be crushed by the metal rings as the memory metal assumes its austenitic state. This leads to a "preconditioning" of the memory metal rings and the tubular member may now be bored out to produce a thin-walled member of the desired bore (.it may be necessary to use a coolant to prevent heating the memory metal rings -to above their ef~ective transition temperature during boring). The connector ~hus produced can be stored and transported at embient temperature, In use -the ends o~ the substrates, e.g. pipes, to be connected are simply inserted into the open ends of the thin-walled tubular member and the whole assembly is then hea-ted to above the ef~ective transiti~n-temperature of the preconditioned memory m~tal whereupon the two metal bands shrink and deform and force the tubular insert .. . ... ...
member into secure conneotion with the pipes, the pipes them- -selves possibly being deformed in the process. Other modifications can, of course, be employed to enable -the tubular member to act both as a mandrel and, later, as a deformable insert, ~or example the tubular member may comprise at least one relatively rigid part to act as the mandrel and ' ., '.' : :

~llr at least one other, relatively, deformable, part.

Conventional heat-shrinkable plastics materials, such as cross-linked polyethylene, may be used in a similar way to thak described above for the preconditioned memory metals. In certain applications of the present invention it may be advantageous for one or more of the bands to be partially prestressed and deformed.

In other embodiments of the present inventlon it may be desirable to form the connector in s u, for example the substrate to be connected can be placed within the tubular member wlth the bands positioned at the narrower ends of the tapers and the assembly can then be cooled, for example by immersion in, or by spraying with, liquid nitrogen whereupon the bands can be pushed up the tapers to deform them. When the bands are properly positioned in their deformed stated the assembly is allowed to warm whereupon the bands contract and form the desired connection. -In other embodiments of the present invention the tubular member may be constructed so as to be considerably deformed as a band is pushed up the taper so that it is effectively pushed into contac~ with the substrate during deformation. In such cases it may be appropriate to provide a relatively deformable substrate such as a pipe with a rigid liner to ensure that some deformation of the band occurs (of course the ~;
deformation need not be so high as 8%) and that a proper connection is made. Alternatively the tubular member may be a composite member comprising, for example, a relatively deformable outer part and a relatively rigid inner part.
~ .
~lowever, such deformation of the tubular member by the band whilst the latte~ is pushed up the taper may be used to .

rr) advantage ln certain appllcatlons. One such appllcatlon ls ln the connectlon of deformable substrates such as stranded cables which can be cornpressed bv up to about 20% of their normal volume before the firm connection is made.
The tubular member or the part thereof whlch contacts the substrate should be made from a material which is compatible with the materlal of the substrate. For example, it should be galvanically acceptable to the sub-strate and, preferably, should combine with the material of the substrate to provide galling and thùs increase the pull-out strength of the connection.
In the preferred connectors of the present invention the tubular member is made from so~t aluminium, which, of course, presents no corrosion problems in the coupling of aluminium pipes, and the metal bands are made from an alloy comprising ma~or proportions of titanium and nickel. Other materials from which the tubular member may advantageously be Eormed include, for example, the engineering plastics materials mentioned above, soft copper and polyethylene.

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Of course, lt will be understood, that in certain applications, the tubular member may itse~f be made from a material which exhibits a relatively high strength at one temperature and a relatively low strength at a second temperature, i.e. the tubular member may itself be made from a heat-recover-able material.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 represents an assembly for use in the present invention;
Figure 2 represents a connector made in accordance with the present invention from the assembly of Figure l;
Figure 3 shows the connector of F:Lgure 2 in position about two pipes to be connected;
Figure 4 shows the resulting connection made;
Figure 5 shows a metal band used in the connector of Figures 1 to

4;
Figure 6 shows a second assembly for use in the present invention;
Figure 7 shows the connector made in accordanca with the present invention from the assembly of Figure 6; and Figure 8 shows the connector of Figure 7 after the bands have shrun~.

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DE~IL~D D~SCRIPTION OF r~ DR~WING5 Referring now to the drawings, in F~guxe 1 there i8 shown a tubular mernber 1 madQ ~rom ~oft alwminium having two tapered portion~ 2 and 3 a~d a central poxtion 4 provided with an

5 annular groove 5 in which there is positioned a split ring 6, al~o made fxom soft aluminium. Two ring~ 7 and 8 are loo~ely po~itioned about the end~ of the tubular mem~er 1~ the~e bands are mad~ from a nickel-titanium alloy.
Figure 2 show~ the po~ition after the r~ng~ 7 and 8 have been forced up the tapered portions ~ and 3, re~pectively, 80 as to expand them, the op~ration having ~een carried ou~ in liquld nitrogen 80 a~ to bring the nickel-titanium alloy into lts weaker, martensitic state. The rings 7 and 8 may ke forced up the tapex u~ing, for example, a ~all hydraulic pres~ or a 15 pair of suitably de~igned tong~. A~ ~how~, ~he rings 7 and 8 _ abut the central split ring 6 which acts a a lo~ating means ~or the xin~
As shown in Figure 3, ~wo aluminium pipe~ 9 an~ 9a are then positioned within the connectorO ~eans may be providad on the inner sur~ac~ of the connector to as~is~ proper location of the pipe~ ~he as embly ~hown in Figure 3 i8 then allowed to warm whereupon tha nickel-titanium alloy a~ume3 it~
a~æ~Qnitic æ~ate and ring~ 7 and 8 s~rink radially to defonm ~he ~oft aluminium member 1 ~o that~ a~ ~hown i~ Figure 4, it ~irmly grip3 pipe~ 9 and 9a.
Figure 5 ~how~, ~n more detail, metal ring 80 As ~hown, the xing i~ provided with a rounded ~dge 10 tc ~acili~ate ~t3 mov0ment up the tapered portion 3.
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~7~3~'7 In a ~pical connector a~ shown in Figure3 1 to 4, the angle o~ taper 1~ 1 S0, corresponding to an outer diameter of about 0.54 inches at the end portion~ and about 0.58 inche~
at the central portion. A coupling made with ~uch a connector S about ~oft aluminium pipe~ haYing an outer diameter o~ 0.5 inche3 lead to a connection which could w.ith~tand an internal pre~ure o up to 2/500 p.s.i. and w~ich had a pulloout ~trength of abou~
500 lb~. ~he connection ~howed no leakage after being ~ubjected to 500 p.~.i. at 50C ~or one hourO ~hu~ the connection ea~ily met the ~tanda~ds required for irrigation piping~
Figures 6 to 8 show a similar ~orm o~ conn~ction in which the tapered portions 12 and 13 o* the tubular member 11 are raversed so that rings 14 and 15 are expanded by pu~hing ~hem ~r~m an ~nitial central position toward~ the end3 of the tubular member ~1 which are provided with annular flange~ 16 and 17 to __ a~siat proper location of the expanded rings ~4 and 1S, respectively.
~ he present inven~ion provide~ a cheap and effectlve way o~ ~ormlng connection~ ~n low co~t, ~igh volume~ applicat~.on~
such as domestlc central heating by employiny the recovery characteristic~ of two mall ring~ in conjunction with a tubular me~ber which act~ both a~ a mandrel to deform the rings in situ :~ an~ al~o a~ an i~ert ~hich e~fectively transmit3 the recovery ~orces of the xings to the pipe~ bein~ coupled. By p~e~onditioning the ring~, a~ de~cribed above, it i~ po~sible to ~tore and transport the connector~ of ~he present invention to customers without resorting to the u~e of cryogenic coola~t~
u~h a~ liquid nitrogen.

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. ; ., . , - , , ~7 Whil~t the present invention ha~ beerl de~cribed wit~i particular reference to the coupling of tubular 3ubstrate~ ~uch a~ pipe~, it will be appreciated that it could equally well be u~ed to connect, ~or example, rod~ and flat strip~, for example to make electrical connection~. Equally, it will be appreciated that, whil~t the tubular member o~ the connector ha~ been de~cribed and illustrated herein a~ being a ~imple one-part ~ember, it could be formed a~ a co~posite member compri~ing, for example, a hollow generally cylindrical part and at lea~t one co-operaiting tapered part (in which ca~e the tapered part(~) could be removed and, i~ desired, be reu~ed)~ Other vaxiation~
and modification~ falling within the ~cope of the pre~ent invention will be apparent to tho~e ~killed in the art.

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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 method of making a connector, which comprises the steps of:
(a) providing a tubular member at least a portion of which has a tapered outer surface;
(b) providing at least one band made from a material which exhibits a relatively low modulus of elasticity at a first temperature and a relatively high modulus of elasticity at a second temperature; and (c) positioning said band about the narrower end of the tapered surface of the tubular member and forcing said band at said first temperature along and against the taper so as to expand it, the relatively high modulus of elasticity of the material of said band being such that when the band is brought to said second temperature it will contract and deform the tubular member.

2. A method as claimed in claim 1, wherein both ends of the tubular member are externally tapered and a band is provided at each of said ends.

3. A method as claimed in claim 2, wherein the ends of said tubular member taper from a central region of greater external diameter to a terminal region of lesser external diameter.

4. A method as claimed in claim 2, wherein the ends of said tubular member taper from a central region of lesser external diameter to a terminal region of greater external diameter.

5. A method as claimed in claim 1, wherein the tubular member is provided with means for facilitating proper positioning of the band after it has been forced up the taper.

6. A method as claimed in claim 5, wherein said means comprises a shoulder formed on the external surface of the tubular member.

7. A method as claimed in claim 5, wherein a separate positioning member is provided on the external surface of the tubular member.

8. A method as claimed in claim 7, wherein the separate positioning member engages a groove and/or protuberance on the external surface of the tubular member.

9. A method as claimed in claim 1, wherein the band is a continuous ring.

10. A method as claimed in claim 1, wherein the inner surface of the band is contoured to facilitate its movement up the taper.

11. A method as claimed in claim 1, wherein the angle of the tapered portion is not greater than 5°.

12. A method as claimed in claim 11, wherein the angle of the tapered portion is from 1° to 2°.

13. A method as claimed in claim 1, wherein the band is made from a memory metal.

14. A method as claimed in claim 13, wherein the memory metal is an alloy of nickel and titanium.

15. A method as claimed in claim 13, wherein the memory metal is a brass.

16. A method as claimed in claim 13, wherein the memory metal has been preconditioned.

17. A method as claimed in claim 1, wherein the band is made from a plastics material.

18. A method as claimed in claim 17, wherein the plastics material is a polyarylene, a polyketone, a polysulphone or a polyphenylene sulphide.

19. A method as claimed in claim 17, wherein the plastics material is cross-linked polyethylene.

20. A method as claimed in claim 1, wherein the length and/or angle of the tapered portion is such that the band cannot be completely pushed up the tapered portion without deforming the tubular member, the tubular member be-ing constructed so that such deformation can take place.

21. A method as claimed in claim 1, wherein a relatively thick-walled tubular member is bored out after deformation of the band(s) to produce a relatively thin-walled coupling member.

22. A method as claimed in claim 1, carried out in situ with one or more substrates positioned within the tubular member.

23. A connector, whenever made by a method as claimed in claim 1.

24. A connector which comprises a tubular member, at least a portion of which has a tapered outer surface, and positioned about said tubular member away from the narrower end of the taper, a band made from a memory material which exhibits a relatively low modulus of elasticity at a first temperature below the transition temperature of the memory material and a relatively high modulus of elasticity at a second temperature above the transition temperature of the memory material, said band being capable of contracting and deforming the tubular member on being brought to said second temperature.

25. A connector as claimed in claim 24, wherein both ends of the tubular member are externally tapered and a band is provided at each of said ends.

26. A connector as claimed in claim 25, wherein the ends of said tubular member taper from a central region of greater external diameter to a terminal region of lesser external diameter.

27. A connector as claimed in claim 25, wherein the ends of said tubular member taper from a central region of lesser external diameter to a terminal region of greater external diameter.

28. A connector as claimed in claim 24, wherein the tubular member is provided with means for facilitating proper positioning of the band.

29. A connector as claimed in claim 28, wherein said means comprises a shoulder formed on the external surface of the tubular member.

30. A connector as claimed in claim 28, wherein a separate positioning member is provided on the external surface of the tubular member.

31. A connector as claimed in claim 30, Warren the separate positioning member engages a groove and/or protuberance on the external surface of the tubular member.

32. A connector as claimed in claim 24, wherein the band is a continuous ring.

33. A connector as claimed in claim 24, wherein the inner surface of the band is contoured to facilitate its movement up the taper.

34. A connector as claimed in claim 24, wherein the angle of the tapered portion is not greater than 5°.

35. A connector as claimed in claim 34, wherein the angle of the taper-ed portion is from 1° to 2°.

36. A connector as claimed in claim 24, wherein the band is made from a memory metal.

37. A connector as claimed in claim 36, wherein the memory metal is an alloy of nickel and titanium.

38. A connector as claimed in claim 36, wherein the memory metal is a brass.

39. A connector as claimed in claim 36, wherein the memory metal has been preconditioned.

40. A connector as claimed in claim 24, wherein the band is made from a plastics material.

41. A connector as claimed in claim 40, wherein the plastics material is a polyarylene, a polyketone, a polysulphone or a polyphenylene sulphide.

42. A connector as claimed in claim 40, wherein the plastics material is cross-linked polyethylene.

43. A method of making a connection to at least one substrate which comprises the steps of:
(a) positioning said substrate within a connector comprising a tubular member, at least a portion of which has a tapered outer surface, and a band positioned about said tubular member away from the narrower end of the taper, the band being made from a material which exhibits a relatively low modulus of elasticity at a first temperature and a relatively high modulus of elasticity at a second temperature and being capable of contracting on being brought to said second temperature, and (b) bringing said band to said second temperature so that it contracts and deforms the tubular member and forces it into firm connection with the substrate.

44. A method as claimed in claim 43, wherein the substrate is a pipe.

45. A method as claimed in claim 43, wherein the substrate is compress-able.

46. A method as claimed in claim 45, wherein the substrate is a stranded cable.

47. A method of making a connection to at least one substrate which com-prises the steps of:
(a) providing a tubular member at least a portion of which has a tapered outer surface;
(b) providing at least one band made from a material which exhibits a relatively low modulus of elasticity at a first temperature and a relatively high modulus of elasticity at a second temperature;
(c) positioning said band about the narrower end of the tapered surface of the tubular member and forcing said band at said first temperature along and against the taper so as to expand it, the relatively high modulus of elasticity of the material of said band being such that when the band is brought to said second temperature it will contract and deform the tubular member;

(d) positioning said substrate within said tubular substrate before, during or after any of said steps (a), (b) and (c), and then (e) bringing said band to said second temperature so that it contracts and deforms the tubular member and forces it into firm connection with the substrate.