DE2802570A1 - ITEMS THAT CAN BE RECOVERED - Google Patents

Description

Rolls House, 7 Rolls Building, Fetter Lane, London EC4

(England)

The invention relates to heat recoverable articles, in particular Memory metal connectors.

It is well known that certain alloys, usually memory metals called, are used for the production of heat-resilient objects, i.e. objects made from have been deformed to an original configuration and which are capable of moving towards theirs when heated reset the original configuration. Such memory metals include, for example, various alloys of titanium and nickel, for example, in U.S. Patents 3,174,851, 3,351,463, 3,753,700, 3,759,552, GB-PS 1,327,441 and 1,327,442 and in NASA publication SP 110 "55-Nitinol-The Alloy with a Memory, etc." (U.S. Government Printing Office, Washington D.C. 1972) are. However, the properties of heat recovery are not limited to such titanium-nickel alloys alone. For example, exhibit different ß-brass alloys this property, as e.g. by N.Nakanishi et al

in "Scripta

^{> v /}

(Pergamon Press 1971) ge-ORIGINAL INSPECTED

was showing. Such materials can be used to lower their transition temperature to low temperature states by means of known Techniques are endowed. 304 stainless steels also show similar properties (E.Enami et al, id, Pages 663-68).

In general, these metals have a transition temperature ranging from -196 to +135 ⁰ C, in particular -196 to -70 ⁰ C, which is the lowest in everyday use temperature to be expected. They can therefore be converted to their martensitic state by immersion in liquid nitrogen. However, it has recently been found that it is possible to "precondition" memory metals to temporarily increase their transition temperature. This makes it possible to store objects made from such alloys at room temperature before use if they can be restored by heating. Such preconditioned methods, as described for example in DT-OS 2.603.878 and 2.603.911, eliminate the need for liquid nitrogen during storage and transport.

Such memory metals have been used to produce mechanical and, in particular, electrical connections. It is referred to in GB-PS 1,327,441, 1,395,601, 1,420,682, 1,439,848 and British patent applications 10117/76 and 42025/76 referenced. The devices described therein have proven to be very effective in making solid mechanical ones Connections have proven to have excellent electrical properties. However, it is at the transition from martensite the degree of dimensional recovery retained in the austenite state especially with certain memory metals, e.g.

ß-metal alloys, because of their relative cost effectiveness and good electrical properties are desired, quite small. That small amount of dimensional reset can create problems in applications where the to-

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Tolerances are not high or where, for example, a subs ^ i-vl, ir it dsm the connection is to be made, like a '' stranded cable, slightly mechanically squeezed vv ^ rUen : ".. ':, before a permanent connection can be made .

Ji = Srfinjung based on the observation that many

^ egiorur-jcn something e'rJ- ^ is ^ h or resiliently yielding sirr "ünci that it ra · - '" ¹ i is, * .iir.t'.-elastic restitution from ei. deformed"·.'. Condition together with their thermal development a £:.; ■ Mutzen una such a greatly improved Cr icl απ κ * 0 dimensional change to get.

The invention relates to a heat-resilient GegensLan · '. the one made of a heat-resilient component made of memory metal consists, which is held in the elastically deformed state by a holding device made of a material which when heated or a chemical treatment softens or changes its shape, creating both thermal and elastic Provision is made possible.

The invention also relates to a method for producing a heat-recoverable article, which is characterized is that you act on the component made of memory metal in its heat-resilient state, a voltage leaves and so gives it an elastically recoverable deformation, this deformation by a holding device a material that will soften or change shape upon heating or chemical treatment will.

The invention also relates to a method for producing a connection, which is characterized in that a connector, which consists of a heat-resettable object made of memory metal, in an elastic-resilient, in an elastic one Area deformed state is held by a releasable or releasable holder and the object is heated

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and is released from the holding device for the purpose of establishing the connection.

A "releasable or releasable holder" is understood below to mean a holding device which is immediately in front of or at the beginning of the resetting can be removed or replaced in order to keep the memory metal object from the deforming Stress relieved without the need for lowering the temperature of the assembly Memory metal object / holder at below conversion temperature exists for the purpose of converting the memory metal into the martensite state. The holding device is preferred arranged between two parts of the memory metal part and separates them in order to maintain the elastic deformation. The parts can have two edges of the component or, for example, two grooves or protrusions specially provided for this purpose be.

For example, the heat recoverable article can be used for manufacture a connection according to the method of the invention in its elastically recoverable state by a holding device are held, which is simply removed for the purpose of elastic recovery, the thermal recovery caused by heating during or after this operation.

However, in preferred embodiments of the invention the detachable holder made of a material which changes its shape when heated or when chemically treated or softened so that it can no longer prevent recovery.

In general, the application of heat is beneficial no separate step is then required for thermal recovery. Therefore, for example, the holding device made of a fusible, heat-softenable or pyrolytic

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be made manageable material. Particularly suitable meltable and heat-softenable materials are thermoplastic Polymers, e.g. homopolymers and copolymers derived from, for example, olefinic monomers such as ethylene, propylene, butene and styrene, unsaturated esters such as vinyl acetate, ethyl acrylate and methyl methacrylate, and other unsaturated monomers, such as acrylonitrile. Other suitable polymer materials are Delryn, the various nylons and polysulfones. Certain low-melting metal alloys, such as lead-tin alloys, can also be used.

Suitable pyrolyzable materials are certain thermosetting ones Polymers such as Bakelite and urea-formaldehyde resins.

There are special things about materials that change their shape when heated the heat recoverable polymer materials such as the in U.S. Patents 2,027,962 and 3,086,242. Heat-restorable metals of the type described above can can also be used for specific purposes.

In some cases, the use of a chemically degradable retainer is appropriate. For example, a volatile organic solvent, such as acetone, on the holding device for the purpose of softening or changing its shape, for example Dissolution or dissolution of a soluble component from the material of the holding device can be used. In other applications, the holding device can advantageously be made from a material such as a polycarbonate which is subject to stress cracking upon treatment with a solvent.

The holding device can be brought into its position during or after the thermally resettable deformation of the object will. In the case of certain alloys, for example, it can be useful, both thermal and elastic

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Make deformation simultaneously while the alloy is in its martensitic state. For example can a tubular sleeve or coupling made of a nickel-titanium alloy deformed either way using a mandrel for radial expansion while in fluid Nitrogen is immersed. The mandrel, in particular a hollow mandrel, can itself serve as a holding device, which finally is removed at the time the connection is established, or preferably a retainer of the type described above is brought into position and the mandrel is removed will.

In the case of preconditioned alloys in particular, the elastic Deformation imparted to the alloy when it is already is in its heat-recoverable form. For example, can one made from a pre-conditioned brass alloy The cut ring is elastically opened and a holding device is installed to prevent it from jumping back will.

In most connector applications of the invention, it is preferred that the retainer not get in the way of the return so that it doesn't disrupt the connection. Another reason for this is to avoid losing it effective dimensional change relative to the substrate because of the Thickness one between the heat recoverable article and holding device enclosed in the substrate.

In certain cases, however, it can be advantageous to use a holding device to use to establish the connection. For example, a holder made of solder can die improve electrical and mechanical properties of the connection, while a holder is made of a thermoplastic Polymers can be used to make a seal or electrical To achieve isolation.

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The object made of heat-recoverable memory metal advantageously has a discontinuity in its cross-section in the Provision level on. For example, particularly useful articles are hollow, such as tubular connectors and rings, and are arranged around the substrates to which the connections are to be made. These items are therefore preferably slit to have a discontinuity in its radial plane. Typical objects are, for example C-shaped rings and tubes cut lengthways.

Such a discontinuity has three advantages. First is the amount of dimensional change that occurs with thermal recovery is obtained, larger than for an otherwise similar object of continuous cross-section, since a bending deformation, which includes both tension and compression components can be applied. Second, it's a lot easier to impart elastic deformation to an object with a discontinuous cross-section. Third, the Holding device to be stored in the discontinuity.

According to a preferred embodiment of the invention is therefore a hollow heat-recoverable article made of memory metal is provided which has a discontinuity in its cross-section has in the restoring plane and in the elastically deformed state by a releasable or releasable Holder stored within the discontinuity is held.

A simple way of making such an article is as follows: A cut tube is expanded on a mandrel and a block or wedge of heat softenable material is inserted into the slot. After removal of the mandrel, the resilient snap back that would normally occur is prevented by the retainer. The expansion through the mandrel can, for example, in the case of

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Nickel-titanium alloys can be used at the same time to impart a thermally recoverable deformation or can, for example, only be used to impart elastic deformation in the case of preconditioned brass alloys will. Such an object can be used at a temperature below the transformation temperature of the alloy in the clamped position State to be stored.

If the holding device is mounted within a discontinuity in the memory metal part, it and / or the memory metal part can preferably have profilings which cooperate to keep the holding device within the discontinuity to keep.

A simple shape is opposite edges of the Memory metal part in the vicinity of the discontinuity worked so that it is exactly parallel in the expanded state Arrangement. In this way there is no risk of the holding device being pushed out by a wedge effect will.

In preferred embodiments, however, are holding devices and / or profiled memory metal part in order to hold the bracket positively in its position.

For example, the edges of the memory metal part can be provided with concave grooves, while the holding device is a rod or a tube. Alternatively, the holding device can be provided with concave grooves, while the edges the have corresponding convex curvature. In another construction of this type, the grooves can be U- or V-shaped, while the edges of the memory metal part or the retainer are shaped to fit in here.

In a particularly preferred embodiment, the Edges of the memory metal part on inclined surfaces, while

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rend the holding device a dovetail-shaped Has cross-section with the inclined sides of the dovetail abutting the inclined surfaces of the edges. At the narrower end of the dovetail, flanges are provided that either fit around the edges of the memory metal part fit its inner or outer surface.

In this and other embodiments it is not essential that the entire holding device can be relieved, in many cases it is sufficient if only part of it is removable or interchangeable to enable resetting. In other applications, especially where a connector to be used to achieve or maintain a seal, the heat-resilient article advantageously a continuous cross-section. In such cases, the holding device is preferably outside (a heat-shrinkable part) or inside (a heat-expandable Part) arranged and shaped in such a way that they are provided with grooves or projections on the surface of the heat-recoverable Object cooperates to keep the latter in the deformed state.

In use, the heat recoverable connector is wrapped around the substrate to which the connection is to be made Positioned, whereupon for the purpose of softening the holding device and increasing the alloy temperature to above transformation temperature is heated. Here, elastic and thermal recovery is obtained at the same time. (Of course it is possible with a low-melting or a chemically-removable or adjustable holder that restore elastic deformation at a temperature below the transition temperature and then the to reset thermal memory deformation by heating to above this temperature.)

A particularly preferred application for such a connection

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as

this consists in the formation of terminations and splices in mineral-insulated electrical cables. Such cables bc ^ - ■ are composed of one or more ladders that are supported by a jacket, usually copper or aluminum / surrounded and powdered contain mineral insulating material, e.g. magnesium oxide. The terminations and splices are common through a sleeve made of heat-restoring material for the purpose of Exclusion of moisture from the insulating material, as beisxjiels-. wisely described in GB-PS 1.098.304, covered. It is desired and increasingly to meet the official Requirement to provide a sheath of such a cable with an earth conductor. In GB-PS 1.428.134 a device was proposed for the simultaneous sealing of a cut rear end of a mineral-insulated cable, in which the earth conductor is in contact with the copper jacket the cable of a heat-resilient plastic sleeve is pressed. However, the connection obtained is mechanical weak.

According to the invention, a mechanically strong earth connection is obtained, by making the hollow heat-recoverable memory metal object arranged inside a heat-resilient polymer sleeve, preferably with a meltable Insert or lining is provided. Such a device can have both an earthing and the provide the necessary sealing for the insulated cable. The temperature at which the holding device softens is preferred lower than the reset temperature of the resilient Plastic sleeve and the melting temperature of the fusible Feed. The heat-recoverable items and that However, methods according to the invention have numerous other uses. Although, therefore, the invention is particularly applicable in connection was described with hollow connectors, '.st them on many forms of resilient objects including, for example, heat-resilient switching elements, forming part of composite devices, applicable,

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The essential concept of the invention therefore consists in the use of a releasable or releasable holding device / to obtain both elastic and thermal recovery. The invention is therefore particularly suitable for alloys at which a significant elastic deformation can be achieved, usually this deformation is greater than 1%, preferably greater than 2%, and the thermally recoverable deformation is typically 2 to 10%.

Obviously, the invention is especially for those Alloys are suitable that have a relatively low degree of thermally recoverable deformation, however have desirable properties for other purposes such as good electrical conductivity. Most brass alloys therefore show, for example, a maximum thermally recoverable deformation of about 4% (compared to, for example, 8% for certain nickel-titanium alloys). However, it is possible according to the invention, a further elastic deformability of 4%, which together results in a resettable deformation of 8%. With nickel-titanium alloys an elastic deformation of up to 2% can be obtained.

While the invention can generally be advantageously applied to all alloys which have both elastic deformation and thermally recoverable deformation, preferably at least 1% of each type of deformation, the invention is particularly useful for alloys which have _N at least 3% of at least one type of deformation , and is particularly suitable for alloys in which the total deformation available exceeds 6%. Within the latter category, for example, nickel-titanium alloys (typical deformations: 2% elastic, 8% thermal), ß-brass alloys (typical deformations: 4% elastic, 4% thermal) and stainless steels (typical deformations:

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6% "elastic / 2% thermal) of those in the preceding To name the types described in the literature.

Various embodiments of the invention are given below by way of example only with reference to the drawings described.

Figure 1 is a perspective view of one embodiment of a connector according to the invention in its heat-recoverable state.

Figure 2 shows, partially in section, a side view of the connector of Figure 1 in position within a heat recoverable Sleeve fitted with a fusible insert.

FIG. 3 shows a side view of the sleeve, partially in section and the connector, "reset around a termination. of a mineral insulated cable.

FIG. 4 shows the arrangement in cross section before resetting a retainer 2 and the edges of the tube 1 of the connector of Figures 1-3.

Figure 5 shows, in cross section, a second form of a suitable one Construction.

Figure 6 is a cross-section of a third suitable arrangement.

Figure 7 is a cross-section through a fourth form of suitable one Arrangement.

FIG. 8 shows a tubular coupling made from a memory metal for use in the invention.

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FIG. 9 shows a heat-recoverable article according to of the invention with the tubular. Coupling of Figure 8

Figure 10 is a second form of heat recoverable article according to the invention with the tubular

Coupling of Figure 8.

Figure 11 shows another form of tubular coupling made of memory metal and

Figure 12 illustrates a heat recoverable article according to the invention including the tubular dome

development of Figure 11.

In Figure 1 there is the connector according to the invention from a slit cylindrical hollow tube 1, which was formed from a preconditioned ß-brass alloy and which is held in the radially expanded state by a main body comprising a wedge of fusible material 2 has, which is embedded between the interruption in the scope. The fusible material can, for example, be polystyrene be. A ground conductor 3 is connected to the slotted tube 1 by suitable means such as solder. Since no fusible material 2 is stored within the slotted tube 1, the entire recovery of the slotted tube for establishing a firm mechanical connection with an electrical one carried out Head available.

In FIG. 2, a fusible insert 5 is arranged in a heat-resilient sleeve 4, the sleeve and the insert are provided with passages 6 and 7 for receiving the ladder from the conclusion. For the sake of simplicity, there are only two Head drawn, although in practice there may be up to five conductors. Inside the fusible insert 5 is arranged the slotted tube 1, which is expanded in radially

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State is held by the fusible part 2. The earth conductor 3 leaves the socket through passage 6.

Figure 3 shows the assembly of Figure 2 reset to a termination of a mineral-insulated cable 8. The cable has a Head 9 exiting through passage 7 from the termination. The slotted tube 1 has sealing engagement around the The copper sheath of the mineral-insulated cable is reset. The fusible insert 5 is completely enclosed by the Completion and formation of a moisture-proof seal flowed. The use of an arrangement according to Figure 2 to create a ground connection and a moisture-proof seal for the completion of a mineral insulated Cable is effected in a very simple way. The arrangement is simply brought into position over the closure, whereby it is ensured that the conductor or conductors of the mineral-insulated cable through the corresponding openings are passed in the arrangement, whereupon is heated for example with hot air or in another suitable manner. The wedge of fusible material then softens and melts, whereupon the slotted tube 1 and the socket 4 contract radially and the fusible insert 5 melts, so that the desired sealed termination is achieved.

Figure 4 shows how the holding device 2 and the opposite Edges of the slotted tube 1 may be shaped to hold the retainer in place prior to resetting keep. In this preferred embodiment, the holding device 2 has a dovetail-shaped part 10, the one with the machined edges and a flange area 11, which is above these edges on the outer surface of the tube, cooperates. Only the dovetail-shaped one Part 10 needs to be fusible.

Figures 5 to 7 show further suitable holding device / edge profiles.

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Figure 8 shows a tubular coupling 21 with four outer flange-like projections 22 are provided. Such Coupling can be deformed by mandrel expansion and then irr. elastically and thermally deformed state by arrangement suitable relieving or releasable holding devices 23 held between adjacent paddles 22, as FIG. 9 shows will. Only two holding devices 23 are shown, but up to four can be used.

Figure 10 shows a similar tubular coupling 31 with four external flange-like projections 32, which in the elastically and thermally deformed state by a single relieved holding device 33 is held, which is arranged over the coupling 31 by sliding in the longitudinal direction will.

Figure 11 shows a tubular device 41, which is attached to her End is provided with inner flange-like projections 42. As shown in Figure 12, the device can longitudinally stretched to a configuration of smaller outer diameter and in elastically deformed! State by one or more unlockable holding devices between the flange-like Projections 42 are held. When resetting, the device 41 contracts in the longitudinal direction with enlargement their outer diameter and can be used, for example, to produce an internal seal for hydraulic pipes or used as a switch.

In the objects of Figures 8 to 12, heat-resilient Parts of continuous cross-section are used and can therefore be used to form connections, for example with or used between pipes in which a seal must be maintained. However, the items can have a discontinuous cross-section, e.g. be slotted.

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The holding device can be designed such that they both softens and changes shape upon heating and / or chemical treatment. Also can be two or several holding devices can be used.

In some embodiments, the holding device
mechanically weakened or deformed for the purpose of resetting ..:

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Claims (38)

Claims ) j Heat-restoring object, characterized by a component made of heat-restoring memory metal, which is held in the elastically deformed state by a holding device made of a material,
which softens or changes its shape when heated or chemically treated, thereby enabling both thermal and elastic recovery. 2) Object according to claim 1, characterized in that the holding device is made of a fusible or heat-softenable material. 3) Article according to claim 2, characterized in that the holding device consists of a thermoplastic polymer is made. 4} object according to claim 2, characterized in that the holding device is made of a low-melting alloy. 5) Object according to claim 1, characterized in that the holding device made of a pyrolysable material is made. 6) Object according to claim 5, characterized in that the holding device is made of Bakelite or a urea-formaldehyde resin. 7) Object according to claim 1, characterized in that the holding device is made of a heat-restoring material. 809830/0897 ORIGINAL INSPECTED 8) Object according to claim 1, characterized in that the holding device is made of a chemically degradable material is made. 9) Object according to claim 8, characterized in that the holding device consists of a polycarbonate. 10) Object according to one of claims 1 to 9, characterized in that that the holding device is outside the return path of the object. 11) Object according to one of claims 1 to 10, characterized in that that the memory metal part is a hollow body. 12) Object according to claim 11, characterized in that the memory metal part has a discontinuity in its cross section has in the Ruckste11ebene. 13) Object according to claim 12, characterized in that the memory metal part is cut open in the longitudinal direction Pipe is. 14) Object according to claim 12, characterized in that the holding device is arranged within the discontinuity. 15) Hollow heat-recoverable object, characterized by a component made of heat-recoverable memory metal, which has a discontinuity in the reset plane and by means of one located within the discontinuity releasable holding device is held in the elastically deformed state. 16) Object according to claim 14 or 15, characterized in that that the memory metal part and / or the retaining material are profiled. 809830/0007 17) Object according to claim 16, characterized in that the opposite edges of the memory metal part in the vicinity of the discontinuity have grooves and the holding device is in the form of a rod or a tube Has. 18) Object according to claim 17, characterized in that the grooves have a partially circular cross-section. 19) Object according to claim 17, characterized in that the grooves are U- or V-shaped. 20) Object according to claim 16, characterized in that the holding device is provided with grooves and the opposite Edges of the memory metal part are shaped so that they cooperate with the grooves. 21) heat-restoring article according to claim 20, characterized characterized in that the grooves have a partially circular cross-section. 22) Object according to claim 20, characterized in that the grooves are U- or V-shaped. 23) Object according to claim 16, characterized in that the opposite edges of the memory metal part in the neighborhood of the discontinuity so profiled are that they have inclined surfaces, while the Holding device has a dovetail-shaped cross-section, with the inclined sides of the dovetail adjoin the sloping edge surfaces. 24) Object according to claim 23, characterized in that at the narrower end of the dovetail flanges are provided around the edges on either the inner or the fit on the outer surface. 809830/0897 - 20 - 25) Heat-restoring object according to claim 11 / characterized in that the hollow memory metal part in the Restoring plane has a continuous cross section. 26) Object according to claim 25, characterized in that the holding device is arranged between grooves in or projections on the surface of the memory metal part. 27) Object according to claim 26, characterized in that the holding device and / or the projections have profiles. 28) Object according to one of claims 1 to 27, characterized in that that the memory metal is brass. 29) Object according to one of claims 1 to 27, characterized in that that the memory metal is a nickel-titanium alloy. 30) Object according to one of claims 1 to 27, characterized in that that the memory metal is a stainless steel. 31) Process for the production of a heat-recoverable object, characterized in that a memory metal part in its heat-resilient state with a Stress is applied, whereby it is given an elastically recoverable elastic deformation and that this deformation is maintained by a holding device made of a material which softens or changes shape when heated or chemically treated. 32) Method according to claim 31, characterized in that the elastic deformation after the thermally recoverable deformation is recorded. 809830/0897 - 2Ί - 33) Method according to claim 31, characterized in that the elastic deformation is carried out simultaneously with the thermally resilient deformation. 34) method for producing a connection, characterized in that that a connector consisting of a heat-resilient memory metal part, which is elastic in the resettable, elastically deformed state is held by a relieving holding device, heated and is freed from the holding device. 35) Method according to claim 34, characterized in that the memory metal part of the holding device for the purpose of elastic recovery before heating for the purpose of thermal Provision is released. 36) Method according to claim 34 or 35, characterized in that that a connection with the M portion of a mineral insulated Cable is established for the purpose of earthing. ' 37) Method according to one of claims 34 to 36, characterized in that that the connection formed is isolated by a heat-recoverable polymer sleeve. 38) Heat-resilient object, characterized by a resilient memory metal part that is elastically deformed in the State is held by a holding device that is set up thereon, then for the purpose both thermal and elastic recovery to be softened or deformed. 809830/0897