GB1585154A

GB1585154A - Heat recoverable article

Info

Publication number: GB1585154A
Application number: GB1779776A
Authority: GB
Original assignee: Raychem NV SA
Current assignee: Commscope Connectivity Belgium BVBA
Priority date: 1976-04-30
Filing date: 1976-04-30
Publication date: 1981-02-25
Also published as: JPS52169089U; CA1091881A; DE7713578U1; JPS589490Y2; FR2349936A1; FR2349936B3

Description

(72) Inventor FRANK KAREL AMEDEUS SELLESLAGS (54) HEAT RECOVERABLE ARTICLE (71) We, N.V. RAYCHEM S.A., a Belgian Company, of Diestsesteenweg 692, 3200 Kessel-lo, Belgium, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement : - This invention relates to a heat-recoverable article, more especially to a heat recoverable sleeve and to a process for the manufacture thereof.

The use of heat-recoverable articles for covering junctions or splices in electric cables is known. The article is usually a heat-shrinkable sleeve, which may either be tubular or in sheet form so that the sleeve may be wrapped around the cable splice after it has been made. The sleeve usually has a layer of sealant or adhesive, e.g., a mastic or hot melt adhesive, applied to its inner surface. Such sleeves are described in U.S. Patent No. 3,297,819 granted on 10th January, 1967 to J. D.

Wetmore and suitable means for joining opposite edges of a wrap-around sleeve are described in U.S. Patent No. 3, 455, 336 granted 15th July, 1969 to R. H. Ellis.

Such articles may be rendered heat-recoverable by heating to or above a certain temperature, expansion, and cooling while retaining an expanded form; one method for achieving this is described in U.S.

Patent No. 3,086,242 to P. M. Cook et al, issued 29th March, 1966. The disclosures of these three patents are incorporated by reference herein.

Many electrical cables are nowadays maintained under internal pressure, to reduce the possibility of moisture penetrating the cable jacket, especially at splices, and damaging the materials or causing shortcircuits. The excess pressure inside the cable may be achieved and maintained by pumps, which are connected to the cables through a valve. It would be convenient to position the valve in the wall of a heatrecoverable sleeve which may be installed e.g., over an aperture in the jacket of the sleeve, so that the site of the sleeve could be used to pressurize the cable. Further, such a valved sleeve may be used as a site for testing the pressure inside a cable. It has been found, however, that despite the use of many different valve mountings, inadequate sealing between the valve and the sleeve has caused leakage, and this problem has inhibited the use of valved sleeves in pressurized cable splicing.

It is also possible to instal a valve in a sleeve over a splice; as an example of a splice in electrical conduits which it would be desirable to pressurize, there may be mentioned that described in N. V. Raychem S.A.'s British Patent No. 1, 431,167, the disclosure of which is incorporated by reference herein.

The present invention provides a heatrecoverable, preferably a heat-shrinkable, sleeve having an appendage, preferably a valve, mounted therein in a portion of the circumferential wall of the sleeve that is dimensionally heat stable, or is subject to significantly less dimensional change than elsewhere in the circumferential wall on recovery thereof.

The sleeve may have one or two open ends, and is preferably tubular. If the sleeve has one closed end, it is to be understood that the valve is not mounted in the end wall, but is mounted in the circumferential wall, i.e., in the case of a tubular sleeve closed at one end, in the tubular wall.

The invention also provides a process for the manufacture of the heat-recoverable sleeve of the invention, which comprises forming the sleeve and rendering it heatrecoverable by heating, deforming and cooling while maintaining it in the deformed configuration, characterized in that deformation of a portion of the circumferential wall of the sleeve is avoided or reduced to a significantly smaller extent than elsewhere on the wall.

The invention also provides a heat recoverable sleeve having an aperture therein in a portion of the circumferential wall that is dimensionally heat stable or is subject to significantly less dimensional change than elsewhere in the circumferential wall on recovery thereof.

In a preferred sleeve constructed according to the invention, there is provided a heat recoverable sleeve having both ends open, and comprising a dimensionally heat stable portion and a heat shrinkable portion, a valve being mounted in an aperture in the heat stable portion.

Although the description will refer more especially to a valve installation, examples of appendages, other than valve installation there may be mentioned an applicator for injection of foamable material into the space enclosed by the sleeve, a pressure indicating or sensing device or an electrical conductor or conductors leading to, for example, a piezo electric device, for sensing pressure or other changes, or leading to means for measuring temperature at points within the space enclosed by the sleeve, e.g. the interface between the internal wall of the sleeve and a substrate enclosed thereby.

The portion of the sleeve may be of a small area, e.g., a disk in the sleeve, it may extend the whole length of the sleeve as a longitudinal band, or it may be, although less desirably, a circumferential band, the shape and size of the portion depending on the intended use of the sleeve and on the processes used in its manufacture.

The portion may result from expansion of the whole sleeve and controlled reshrinkage in the desired area, but advantageously results from expansion of the remainder of the sleeve only, and prevention or control of expansion of the portion during manufacture.

For example, if a tube is expanded by passing through a heating means while it is subjected to excess internal pressure heat may be prevented from reaching a portion of the circumference of the tube by an insulating or blocking device, resulting in a longitudinal band of non-shrinkable or less shrinkable material extending the length of the tube, the band appearing as a portion of greater wall thickness. The tube may then be cut into sleeves of appropriate length, an aperture made in the band, and a valve mounted in the aperture. Another possible method comprises positioning a suitably shaped member, e.g., a disk or rectangle of suitable material, e.g., aluminium, at intervals on a tube to be expanded, whereby heat may be prevented from reaching the tube at the regions under the member, and expansion restricted, for example because the member acts as a heat sink. As a further method, the tube may be subjected to uniform heating superimposed on which is a selective cooling of one position to prevent or reduce expansion.

It will be apparent as indicated above that the invention may be employed where other appendages, e.g., devices other than valves, are to be incorporated into heatrecoverabale articles and is useful in all instances where proper functioning is dependent to some extent on proper attachment of the device to the sleeve.

Two forms of article constructed in accordance with the invention will now be described in greater detail by way of example with reference to the accompanying drawings, in which FIG. 1 is a perspective view of a valved heat-shrinkable sleeve having a longitudinal band of non-shrinkable material; and FIG. 2 is a cross-section through a valved heat-shrinkable sleeve having a valve mounted in a non-shrinkable zone.

Referring to Fig. 1, a sleeve indicated generally by the reference numeral 1 is generally heat-shrinkable with a longitudinal band 2 being less shrinkable or dimensionally heat stable. Mounted in the band 2 is a valve 3. On recovery of the sleeve, the wall thickness of the band 2 will remain substantially constant, while the remainder of the sleeve will contract radially with resulting wall thickness increase.

Figure 2 illustrates a cross-section of sleeve 1 having a disk 4 of unexpanded material, the valve 3 being centered in the disk.

WHAT WE CLAIM IS : 1. A heat recoverable sleeve having an appendage mounted therein in a portion of the circumferential wall of the sleeve that is dimensionally heat stable or is subject to significantly less dimensional change than elsewhere in the circumferential wall on recovery thereof.

2. A sleeve as claimed in claim 1, wherein the portion of the sleeve extends along the sleeve in a longitudinal band.

3. A sleeve as claimed in claim 1, wherein the portion of the sleeve is circular.

4. A sleeve as claimed in claim 1, wherein the appendage is a valve.

5. A sleeve as claimed in claim 2 or claim 3, wherein the appendage is a valve.

6. A sleeve as claimed in any one of claims 1 to 5, which is tubular.

7. A sleeve as claimed in any one of claims 1 to 6, which is open at both ends.

8. A sleeve as claimed in any one of claims 1 to 7, which is heat-shrinkable.

9. A sleeve as claimed in claim 1, substantially as described with reference to and as illustrated by Fig. 1 or Fig. 2 of the accompanying drawings.

10. A process for the manufacture of a heat-recoverable sleeve as claimed in claim 1, which comprises forming the sleeve and rendering it heat-recoverable by heating, deforming and cooling while

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. on recovery thereof. In a preferred sleeve constructed according to the invention, there is provided a heat recoverable sleeve having both ends open, and comprising a dimensionally heat stable portion and a heat shrinkable portion, a valve being mounted in an aperture in the heat stable portion. Although the description will refer more especially to a valve installation, examples of appendages, other than valve installation there may be mentioned an applicator for injection of foamable material into the space enclosed by the sleeve, a pressure indicating or sensing device or an electrical conductor or conductors leading to, for example, a piezo electric device, for sensing pressure or other changes, or leading to means for measuring temperature at points within the space enclosed by the sleeve, e.g. the interface between the internal wall of the sleeve and a substrate enclosed thereby. The portion of the sleeve may be of a small area, e.g., a disk in the sleeve, it may extend the whole length of the sleeve as a longitudinal band, or it may be, although less desirably, a circumferential band, the shape and size of the portion depending on the intended use of the sleeve and on the processes used in its manufacture. The portion may result from expansion of the whole sleeve and controlled reshrinkage in the desired area, but advantageously results from expansion of the remainder of the sleeve only, and prevention or control of expansion of the portion during manufacture. For example, if a tube is expanded by passing through a heating means while it is subjected to excess internal pressure heat may be prevented from reaching a portion of the circumference of the tube by an insulating or blocking device, resulting in a longitudinal band of non-shrinkable or less shrinkable material extending the length of the tube, the band appearing as a portion of greater wall thickness. The tube may then be cut into sleeves of appropriate length, an aperture made in the band, and a valve mounted in the aperture. Another possible method comprises positioning a suitably shaped member, e.g., a disk or rectangle of suitable material, e.g., aluminium, at intervals on a tube to be expanded, whereby heat may be prevented from reaching the tube at the regions under the member, and expansion restricted, for example because the member acts as a heat sink. As a further method, the tube may be subjected to uniform heating superimposed on which is a selective cooling of one position to prevent or reduce expansion. It will be apparent as indicated above that the invention may be employed where other appendages, e.g., devices other than valves, are to be incorporated into heatrecoverabale articles and is useful in all instances where proper functioning is dependent to some extent on proper attachment of the device to the sleeve. Two forms of article constructed in accordance with the invention will now be described in greater detail by way of example with reference to the accompanying drawings, in which FIG. 1 is a perspective view of a valved heat-shrinkable sleeve having a longitudinal band of non-shrinkable material; and FIG. 2 is a cross-section through a valved heat-shrinkable sleeve having a valve mounted in a non-shrinkable zone. Referring to Fig. 1, a sleeve indicated generally by the reference numeral 1 is generally heat-shrinkable with a longitudinal band 2 being less shrinkable or dimensionally heat stable. Mounted in the band 2 is a valve 3. On recovery of the sleeve, the wall thickness of the band 2 will remain substantially constant, while the remainder of the sleeve will contract radially with resulting wall thickness increase. Figure 2 illustrates a cross-section of sleeve 1 having a disk 4 of unexpanded material, the valve 3 being centered in the disk. WHAT WE CLAIM IS :

1. A heat recoverable sleeve having an appendage mounted therein in a portion of the circumferential wall of the sleeve that is dimensionally heat stable or is subject to significantly less dimensional change than elsewhere in the circumferential wall on recovery thereof.

4. A sleeve as claimed in claim 1, wherein the appendage is a valve.

5. A sleeve as claimed in claim 2 or claim 3, wherein the appendage is a valve.

6. A sleeve as claimed in any one of claims 1 to 5, which is tubular.

7. A sleeve as claimed in any one of claims 1 to 6, which is open at both ends.

8. A sleeve as claimed in any one of claims 1 to 7, which is heat-shrinkable.

maintaining it in the deformed configuration characterized in that deformation of a portion of the circumferential wall of the sleeve is avoided or reduced to a significantly smaller extent than elsewhere on the wall.

11. A process as claimed in claim 10, wherein the sleeve is rendered heat-shrinkable.

12. A process as claimed in claim 10 or claim 11, wherein the portion is a longitudinal band extending along the length of the sleeve or is a disk.

13. A process as claimed in any one of claims 10 to 12, wherein avoidance or reduction of deformation is achieved by preventing heat from reaching the portion.

14. A sleeve as claimed in claim 1, whenever made by a process as claimed in any one of claims 10 to 13.

15. A heat recoverable sleeve having an aperture therein in a portion of the circumferential wall that is dimensionally heat stable or is subject to significantly less dimensional change than elsewhere in the circumferential wall on recovery thereof.

16. A sleeve as claimed in claim 15, wherein the portion extends along the sleeve in a longitudinal band.

17. A sleeve as claimed in claim 15, wherein the portion is circular.

18. A sleeve as claimed in any one of claims 15 to 17, which is heat-shrinkable.

19. A heat recoverable sleeve having both ends open, and comprising a dimensionally heat stable portion and a heatshrinkable portion, a valve being mounted in an aperture in the heat stable portion.