CA1079326A

CA1079326A - Tapered inserts

Info

Publication number: CA1079326A
Application number: CA249,952A
Authority: CA
Inventors: Charles L. Martin
Original assignee: Raychem Corp
Current assignee: Raychem Corp
Priority date: 1975-04-09
Filing date: 1976-04-09
Publication date: 1980-06-10
Also published as: US4951978A; SE434564B; AU1288876A; ES446856A1; NL184975C; BE840620R; GB1553427A; US4874193A; DE2615685A1; ZA762158B; SE7504070L; NL7603809A; AU518185B2; JPH0237485B2; IT1059062B; NL184975B; US4455041A; JPS51123919A; JPS61180087A

Abstract

ABSTRACT

Composite coupling devices, especially useful for joining cylindrical substrates, comprise a perferably tubular heat-recoverable memory metal member, usually a radially heat-shrinkable member called a driver, and at least one sleeve member disposed inside or outside said memory metal member, usually an insert. The insert has at least part of at least one of its principal surfaces tapered so that it can accommodate size variations within the substrate(s). In preferred embodi-ments a least two inserts are provided with complementary tapered principal surfaces whereby they can be brought into tight contact with each other and the substrate(s) prior to recovery of the driver.

Description

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This inv~ntion relates to composite coupling devices, especially those described in Belgian Patent No. 820,880 and corres-ponding Canadian Application Serial No. 211,056 filed 9th October3 1974 in the name of C. L. Martin.
The composite coupling devices described and claimed in the above applications comprise a "driver", or heat-recoverable member, made from a memory metal and a second, sleeve memb~r, usually an insert member, which is so constructed, and/or fabri-cated from such a material, that it enhances the coupling o the composite device to a substrate or substrates. Typically, the "driver" memb0r and the "insert" member are both generally tubular and the insert member is provided with teeth and/or is made from a gall-prone material and/or is provided wi~h portions, such as slots or grooves, of relative weakness, and/or is made from a material with other desirable properties having regard to the particular application of the composite coupling device.
As is explained in the above application, ''memory metals"
are alloys which exhibit changes in s~rength and conEigurational characteristics on passing through a transi~ion temperature, in most cases the transiton ~e~perature between ~he martensitic and austenitic states, and can ba used to make heat~recoverable articles by de~ ng an article made from them whilst the metal is in its martensitic, low temperature, state. The article will retain its de~ormed configuration until it is warmed above the transition temperature to the austenitic state when it will recover towards .
its original configuration. The deforDation used to place the

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material in thc h~at-unstable configuration is commonly ref~rred to as ~hermally recov~rable plastic deformation and can also, in certain cases, be imparted by introducing strains into the article above the transition temperature, whereupon the article assumes the deformed configuration on cooling through the transition temperature.
It should be understood that the transition temperature may be a temperature range and that, as hysteresis usually occurs, the precise temperature a~ which ~ransi~ion occurs may depend on whether the temperature is rising orf~lling. Furthermora, the transition temperature is a function of other para~eters, including the stress applied to ~he material, the temperature rising with increasing stress.
Amongst such memory metals there may especially be mention-ed various alloys of titanium and nickel which are described, ~or example, in United States Patents No.s. 3,174,851, 3,351,463,

3,753,700, 3,759,552, British Patents Nos, 1,327,~441 and 1,327,442 and NASA Publication SP 5000~ "55-Nitinol-The Alloy with a Memory, etc." (United States Govern~en~ Printing Office, Washington, D.C.
1972~. The property of heat reco~erability has not, however, been solely confined to such titanium-nickel alloys. Thus, for example, various copper-based alloys ha~e been demnnstrated to exhibit this property in, e.g. M. Nakanishi e~ al, 433-440 (Pergamon Press 1971) and such materials may be doped to lower their transition temperatures to cryogenic regimes by known techniques. Si~ilarly, type 304 stainless steels have been shown :

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to enjoy such characteristics, E. enami et al, id at pp. 663-68.
ese disclosures are similarly incorporated herein by refer-ence.
In general, the ~lloys are chosen to have transition temperatures between the boiling point of liquid nitrogen, -196C, and room temperature or the lowest temperature likely ~o be encountered in opeTation, i.e. between -196C and -75C in many aerospace applications. This enables the articles made from the alloys to be deformed to the confi~uration from which recovery is desired, and stored, in liquid nitro~cn and yet ensures that after heat recovery there is no danger of loss of mechanical strength during use by reason of ~he article encountering a temperature at which it reverts to the martensi~ic state.
However, storage of the defor~ed article in liquid nitrogen is sometimes inconvenien~. Recently processes have been developed by which metallic compositions, particularly certain copper-based alloys, can have the transition temperature at which they rever~ to the austeni~ic state transiently elevated ~rom the temperature at which this normally occurs to a higher temperature, typically above room temperature. Subsequent re-covery requires that ths article be heated. Such alloys are re~erred to as being "precondition." Procedures by which they aTe preconditioned are descr;bed in Canadian- Applications Serial Nos. 186,167 and 247,057 and Belgian Patent 838,197.
As indicatcd above, by application of a precondition-

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ing process to an alloy its transition temperatllre can be elevat~
ed. However, once recovery has been brought about by heating the article through its new transition temperature, ~he alloy's response to temperature change rever~s to that it possessed prior to preconditioning. Accordingly, it remains austenitic until cooled to the temperature at which transition to martensite normally occurs, typically chosen to be at 0C or below depending upon the temperature environment likely to be encountered.
A typical application for the composite couplings describ ed in the aforementioned Martin application is to join tubular or cylindrical substrates. Properly dimensioned, these couplings can be employed to join substrate that vary greatly in size. For example7 they might find application in joining tubing sections that could be used for hydraulic systems in aircraft. They can also be used to join sections of pipe of very large dimension.
In many situations the tolerance criteria for the cylin-drical substrates to be joined are such that there can be signi-ficant variation in size between sections, for sxample of the order of 5% or even more, and the substrate may be significantly out of round. Also, it is frequently desired to connect substrates that vary somewhat in size. Accordingly, there is a need or composite couplings capable of accommodating such irregularities or variations in the substrate.
The present invention provides composite couplings capable of meeting this need. These couplings comprise a heat-shrinkable : -.!

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driver made from a memory metal in combination with at least one sleeve member that has a tapered surface, which may be either the interior or exterior surface, in order that i-t can co-operate with the substrate itself, ye-t another insert having an inverse taper, or the driver, in order to accommodate differences in size between sections o~ cylindrical substrate or compensa-te for their being out of round. To improve the retention of the substrate within the coupling, an insert may be provided -~ith serrations or teeth or be made from a gall-prone member so that the occurrence of galling between it and the substrate stren~thens the join-t.
The present invention accordingly provides a composite device comprising at least one hea-t-shrinkable or he~t-expansible hollow memory metal member and at least one sleeve member positioned respectivel~ inside or outside said hollow member, at least part of at least one principal sur~ace of the sleeve member being tapered.
In some cases the hollow memory metal member may be heat-expansible and the or each sleeve member is positioned round it.
However, in most pre~erred embodiments o~ the present invantion the hollow memory metal memher is a heat-shr;nkable tubular member and the or each sleeve member is an insert mem~er co-axially disposed within it and, ~or convenience, the present invention -~
will from hereon be described in terms of heat-shrinkable tubular metal members having one or more insert members positioned within them.
The term "tubular" as used herein is not limited to right : .

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cylindrical members, but includes members of irr~gular and/or of varying cross-section as well as, for examp]e, Y-shaped, T-shaped and X-shaped member, and alæo members having one or more closed ends.
The oompcsite devices of the present invention may comprise only one insert member in which case the insert member may have an inner principal surface which is doubly-tapered towards or away from its centre to ~ac~litate the positioning o~ two cylindrical substrates, e.g. pipes, which are to be connected.
However, in most preferred embodiments of the present invention at least two insert members are provided, the tapered surfaces of these members being complementary and in contact.
The outer member o~ the apir is tapered on its ~nner surface and the inner member o~ the pair i8 tapered on its outer surface with slopes that allow the surfaces to contact each other as one is moved ralative to the oter along their common longitudinal axis. By reason o~ this movement, the coaction of the tapered ~urfaces of the insert members can cause the inner member to be ~-deformed in order to conform and more securely engage the sub~
strate prior to recovery of the driver. In this way~ less of the ~orce exerted ~y the dr~ver is expended in initiall~ deforming the insert to conform to the substrate and a more uniform force is exerted upon recovery o~ t~e dri~er.
In other composite devices accord~ng to the present inven-tion there are provided three insert members one o~ which has a principal sur~ace which ~s doubly-tapered towards or away from its centraI reg~on and the other two of wh~ch each have a singly-tapered princ~pal sur~ace which is complementary to one of the ~7-, .. . .

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tapered portions of the principal surface of the ~irst sleeve member. Again means are preferably provided for moving the two singly-tapered sleeve members rela-tive to the doubly-tapered sleeve member, preferably -tow~rds each other, 80 as to form a tight connection prior to recovery. Various arrangements of the three members are possible. For example, in one device the single doubly-tapered sleeve member has an outer surface of relatively uniform diameter and an inner surface tha-t tapers from a greater diameter near its ends to a lesser diameter in its central region, and the two singly-tapered sleeve members are positioned in contact with said inner surface on either side of said central region, each of these members having an inner surface of relatively uniform diameter and an outer surface which tapers from a greater diameter near its outer end to a lesser diameter near its inner end, In another device the single doubly-tapered sleeve member has an inner surface of relatively uniform diameter and an outer surface that tapers from a lesser diameter near its ends to a greater diameter in its central region, and the two singly-tapered sleeve members are positioned in contact with said outersurface on either side of said central region, each of these member having an outer sur~ace o~ relatively uni~orm diameter and an inner surface~which tapers from a lesser diameter near its outer end to a greater diameter near its inner end.
In yet another de~ice the single doubly-tapered sleeve member ha~ an inner surface of relatively uniform diameter and an outer surface that tapers ~rom a greater diameter near its ends . .. ~ . . . . : .
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In all of these embodiments and in many other embodiments of the present invention it is preferred that a portion of at least one insert member is threaded and provided wlth tightening nuts to facilitate the movement of the various inser-t members to obtain a tight fit prior to receovery. In some embodiments the tigh-tening nuts themselves may advantageously comprise or form par-t of the hollow heat-shrinkable memory metal member.
Various embodiments according to the present invention will now be described in more details, by way o~ example only, with reference to the accompanying drawings, in which:
Figures la and lb illustrate a composite coupling for joining c~lindrical substrates that differ in diameter;
Figure 2 illustrates another form of composite coupling for joining c~lindrical substrate;
Figure 3 illustrates a composite coupling for flu;d tig~t connections;
Figure illustrates ~et another composite device for ~
coupl~ng cylindrical substrates; ~ -Figure 5 illustrates a ~urther form of coupling device;
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Figure 6 illustrates another form Oe coupling device.
Referring to the drawings:
Figures la and lb illustrate the use ot` a composite device according to the present invention for joining tubular substrates.
As shown in Figure la, heat-recoverable driver 2 is provided with an insert 1 which has a constant outside diameter but which is tapered internally from a maximum intern~l diameter at its ends toaa minimum internal diameter near its centre. As a result of this internal taper, each end of insert 1 is capable of receiving tubular substrates 3 and 4 which may be of the same ~r di~ferent diameter. Also by reason of its taper, insert 1 is capable of accommodating a wider range of substrate diame-ters than would an inser-t of constant internal diameter.
As shown in Figure lb, insert member 1 may be provided with serrations or teeth to enable it better to grip -the substrate when recovery has occurred. Insert me~ber 2 may also be made of a gall-prone metal relative to the substrate.
Another device according to the presant lnvention, after recovery, is shown in Figure 2. The device comprises two insert members 5 and 6, the outer membe~ 5 being tapered internally from a maximum internal diameter at one end to a minimum internal diameter at the other. As shown, mem~er 5 ~s provided with longitudinal slots 7 at the end o~ maximum internal diameter to facilitate its de~ormation upon recover~. Inner member 6 is provided with an outer taper complementar~ to that of member 5 in that it *apers from a maximum outside diameter ~t one end -to a minimum at the other. Member 6 is provided with terminal longi-.
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tudinal slots 8 at either end to facilitate its deformation. Asshown in Figure 2, inner member 6 is provided with teeth to inhibit -the withdrawal of tubular members 9 and 10 after recovery by forming circumferential dents 11 and 12.
Prior to recovery of driver 13, members S and 6 are wedged closely together, member 5 acting upon member 6 to compensate for variations in the substrate' 5 outside diameter o~ substrate ovalness.
Another device according to the present inven-tion -that will accommodate cylindrical substrates havin~ a large variation in outside diameter is shown in Figure 3, As shown, the device comprises three tapered insert members 14 7 15 and 16. Outer member 14 is provided with threaded end portions 17 and 18 and tapers internally between between the threaded portions to a minimum inside diameter ~t its centre. As shown~ member 14 is provided with longitudinal slots between its threaded sections to facilitate its deformation by the driver upon recover~ of the latter. Inner members 15 and 16 are tapered on their outside ~rom a maximum outside diameter at one end to a m~n~mum at the other and prefer-ably are provided with terminal longitudinal slots as shown. Asshown in Figure 3, the inner members can be provided w;*h teeth to engage the substrates, f tubular sec-tions 19 and 20.
Prior to recovery, the tubular substrates~ which can have the same or dif~erent outside diameters, are introduced into the aperture formed by members 15 and 16. Tightening nuts 21 and 22 pr0vide m~ans by which members 15 and 16 can be advanced into member 14 initiall~ to engage substrate sections 19 and 20. It :

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5a3~j will be apparent that the furthes-t advance of members 15 and 16 is dictated by -the diameter of the substrate sections. If the substrate is to carry fluid, O~ring type ga6kets 23 and 24 can be provided for sealing purposes. To protect member 14 from a corrosive fluid, a toothed ring 25 can be inserted between members 15 and 16 to make the joint 1uid tight. Of course ring 25 must be of a material resistant to the fluid. Between the tightening nuts and members 15 and 16 can be disposed washers 26 and 27.

When ring 25 is employed, gaskets 23 and 24 may be omitted.
In Figure 4, there is shown a variant of the device of Figure 3. As shown in Figure 4, the device again comprises -three insert parts. However, in this embodiment, the inner member 28 has threaded ends 29 and 30 to receive tightening nuts 31 and 32 which are employed to advance tapered ~uter members 33 and 34.
By their advancement, insert members 33 and 34 force member 28 into close contact w~th substrate sections 35 and 35a prior to recovery o~ dri~er member 36~ Preferably, the inser-t members are slotted to facilitate de~ormation.
In the device o~ both Figures 3 and 4, the provision for oppositely tapered members provide means by which th~ inner member can be deformed prior to rec~very of the dr~ver to conform to the substrate. Thus ~hen recovery is cau~ed to occur, a larger portion of the recovery force can be asserted to brin~ the insert(s) and substrate into more intimate engagement rather than being partially disslpated by`hAving first to de~orm the insert(s).
Ano~her device according to the present ~vention is depicted in Figure S. In t~at dev~ce, outer surface of inner ::
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member 37 is tapered from a maximum diameter clt its ends to a minimum diameter at its centre. As shown, it is provided with teeth and has longitudinal slots. Outer members 38 and 39 are internally tapered to co-operate with member 37. Outer members 38 and 39 are threaded at their ends to receive tightening nuts 40 and 41. The action of these nuts is to withdraw elements 38 and 39 which has the effect of ~eforming inner member 37 to cause it to engage substrates 42 and 43. When this has been accomplished, recoverable driver 44 is warmed above its transition temperature to provide the final pressure required by the coupling.
Figure 6 illustrates another varian-t o~ the present inven-tion which comrpises a single insert member 45, preferably slotted, which is ~enerally cylindrical and externally tapered from a m~ni-mum outside diameter at its ends to a maximum at its centre. The insert 45 is threaded from its ends to receive nuts 47 and 48 which also function as heat recoverable drivers, i.e. they are -capable of recovering to a smaller dimension. Centre section 46 of insert 45 is provided w~th lugs to allow it to be held without rotation when the nuts are installed. Insert 45 is preferably provided with internal teeth as shown.
Each nut is rendered heat-recoverable by mandrel expansion while the nut is at a temperature at which it exists in -the mar-tensitic state. The threads can be protected during expansion by providing the nut with a threaded liner of the aame alloy that can be screwed into and out of the nut. The nut is preferably pre-conditioned a~ter exp~nsion to elevate the temperature at which it reverts to martensitic to ensure that the transi-tion does not . "''' '. ' ' 32~;

prema-turely occur during the installation of -the coupling.
Once the substrates 49 and 50 have been inserted in the aperture de~ined by insert 45, the nuts are tightened inltially to deform the insert and adap-t its conformation to the irregu-larities of the substrates. The nu~s are then heated to occasion their recovery and thereby tightly engage the insert and substrate~.
The couplings previously described are but illustrative of the many forms the present in~ention may take. It will be apparent that the composite couplings of this invention are suited to many applications where the joining of cylindrlcal substrates is desired. For example, they might be employed to join solid or tubular structur~l members or cable. However, the preferred application for these couplings is in the union of hollow members adapted to convey fluids, for example fluids in h~draulic systems or pipelines.

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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 device for coupling together tubes or other substrates, which de-vice comprises a heat-shrinkable or heat-expansible member which is made from a memory metal and is shaped to fit around or within said substrates, said heat-shrinkable or heat-expansible member having been made by applying stress to it in an original configuration to cause it to adopt a deformed configura-tion at a temperature below the transition temperature and being capable of shrinking or expanding, respectively, towards said original configuration on being warmed to or above said transition temperature, the device also compris-ing a sleeve member having one or more parts positioned respectively inside or outside said heat-shrinkable or heat-expansible member and in close proximity thereto, the size, shape and surface characteristics of said sleeve member combining to ensure an improved coupling of the substrates following shrinkage or expansion respectively of said heat-shrinkable or heat-expansible member, characterised in that at least part of at least one principal surface of the second member or one of the parts thereof is tapered so that the device can accomodate size and/or shape variations in a substrate to be coupled.

2. A composite device as claimed in claim 1, wherein the hollow memory metal member is a radially heat-shrinkable tubular member.

3. A composite device as claimed in claim 2, wherein the sleeve member is co-axially disposed within said heat-shrinkable tubular member.

4. A composite device as claimed in claim 1, wherein the contacting sur-faces of the hollow memory metal member and the sleeve member are non-tapered.

5. A composite device as claimed in claim 1, wherein the principal sur-face of the sleeve member remote from the hollow memory metal member is provided with a plurality of teeth.

6. A composite device as claimed in claim 1, wherein the sleeve member is structurally weakened to facilitate its deformation.

7. A composite device as claimed in claim 1, wherein the sleeve member is made from a gall-prone material.

8. A composite device as claimed in claim 1, wherein a single sleeve member is provided which has at least one principal surface which is doubly tapered towards or away from its centre.

9. A composite device as claimed in claim 8, wherein the inner surface of said sleeve member has a generally uniform diameter and the outer surface tapers from a lesser diameter near each end to a greater diameter in its central region, said outer surface being threaded, and two heat-shrinkable hollow members are provided in the form of internally screw-threaded members which can be advanced up the threaded tapered surfaces of the sleeve member prior to their recovery.

10. A composite device as claimed in claim 8, wherein the outer surface of the sleeve member has a generally uniform diameter and the inner surface tapers from a greater diameter near each end to a lesser diameter in its central region.

11. A composite device as claimed in claim 9, wherein the inner surface of the sleeve member is provided with a plurality of teeth.

12. A composite device as claimed in claim 1, characterized in that the sleeve member comprises at least two generally co-axially disposed components haying contacting surfaces which taper in opposite directions.

13. A composite device as claimed in claim 12, wherein means are provided for moving said components relative to each other in the direction of their common longitudinal axis.

14. A composite device as claimed in claim 13, wherein said means comprise at least one threaded nut.

15. A composite device as claimed in claim 14, wherein the threaded nut comprise or forms part of the heat-shrinkable hollow member.

16. A composite device as claimed in claim 12, characterised in that the second member comprises one component, one surface of which is doubly tapered towards or away from its centre and two-co-operating tapered end components.

17. A composite device as claimed in claim 16, wherein means are provided for moving the two singly-tapered components towards or away from each other.

18. A composite device as claimed in claim 17, wherein said means comprise a pair of nuts which co-operate with threaded ends on the doubly-tapered component.

19. A composite device as claimed in claim 16, wherein the single doubly-tapered component has an outer surface of relatively uniform diameter and an inner surface that tapers from a greater diameter near its end to a lesser diameter in its central region, and the two singly-tapered components are positioned in contact with said inner surface on either side of said central region, each of these component having an inner surface of relatively uniform diameter and an outer surface which tapers from a greater diameter near its outer end to a lesser diameter near its inner end.

20. A composite device as claimed in claim 16, wherein the single doubly-tapered component has an inner surface of relatively uniform diameter and an outer surface that tapers from a less diameter near its ends to a greater diameter in its central region, and the two singly-tapered components are positioned in contact with said outer surface on either side of said central region, each of these components having an outer surface of relative-ly uniform diameter and an inner surface which tapers from a lesser diameter near its outer end to a greater diameter near its inner end.

21. A composite device as claimed in claim 16, wherein the single doubly-tapered component has an inner surface of relatively uniform diameter and an outer surface that tapers from a greater diameter near its ends to a lesser diameter in its central region, and the two singly-tapered components are positioned in contact with said outer surface on either side of said central region, each of these components having an inner surface of relative-ly uniform diameter and an outer surface which tapers from a greater diameter near its outer end to a lesser diameter near its inner end.

22. A composite device as claimed in claim 1, wherein the memory metal is a preconditioned alloy.