Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1992-07-13
1994-06-07
Rosenbaum, Mark
Metal working
Method of mechanical manufacture
Assembling or joining
264DIG71, 174DIG8, 156 86, B23P 1102
Patent
active
053177975
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of enclosing a substrate, particularly to provide environmental protection, especially by employing a heat-shrinkable sleeve, and preferably where the substrate comprises a cable or a pipe, particularly a telecommunications cable.
Environmental protection is required around cable splices generally to make good a cable Jacket that has been removed from the cable ends to expose the internal conductors for electrical (or optical) splicing. A cable splice case is built up around the cable splice such that it bridges intact cable Jacket at each side of the splice. In this way contaminants such as moisture can be kept away from the otherwise exposed conductor splices. Splice cases are now commonly made by installing around the splice a dimensionally-recoverable, usually heat-shrinkable, sleeve. A heat-shrinkable sleeve may be supplied over-size, and then heated to cause close, environmentally-sealing, fitting to the underlying cable splice. A wrap-around heat-shrinkable sleeve is disclosed in GB 1155470 (Raychem).
A sleeve may be installed directly over the cable splice or other substrate to be protected, or a liner or other article may first be installed and the sleeve then shrunk around the liner. Such a liner may give mechanical strength to the resulting splice case, may protect the substrate from the heat applied during heat-shrinkage of the sleeve, or may add to the water-vapour barrier properties of the sleeve. Where the substrate is of non-uniform cross-sectional size (as in the case of a cable splice that is of larger diameter at its centre, and tapers down to the diameter of the spliced cables at its ends) the liner may serve to render the changes in size smooth thereby facilitating installation of the sleeve. In order to do this the liner may have frusto-conical ends, which may be produced by providing tapering fingers at the ends of a cylinder (giving the appearance of crowns) which are then bent inwards towards the axis of the cylinder. The cylinders may, for example, comprise two half-shells or may result from rolling up an initially substantially flat sheet. Such liners are described in GB 1431167 (Raychem).
The ability to communicate with the inside of a splice case may be useful, for example to monitor or to change conditions therein. For example, some telecommunications cables are pressurized with dry air to protect them, and pressure access points are needed for supply of air or for testing. In order to do this some line such as a pressure-access tube must pass through the sleeve, or between the sleeve and the substrate enclosed thereby. This has been suggested in, for example, EP 0244209 (Raychem) which discloses provision of a valve in the sleeve. Electrical or other communication may be required for other purposes, and GB 2112224 (Raychem) may be cited as a further example.
A different approach is taken in U.S. Pat. No. 4400579 (the disclosure of which is incorporated herein by reference) which relates principally to sealing a branch-off between two cables using a heat-shrinkable sleeve and a clip between them that forms two conduits in an end of the sleeve. That patent discloses an assembly comprising a heat-shrinkable sleeve capable of being positioned around at least first and second elongate substrates, and a clip having at least two elongate legs capable of being positioned over the outer surface of the sleeve at an end thereof so as to form, and maintain during subsequent heat-shrinkage of the sleeve, at least two terminal conduits respectively capable of receiving the first and second substrates, the clip optionally being formed as a trident with the central leg of the trident inside the sleeve. The central leg of the trident may be hollow to provide an inlet for pressurized air within a cable splice. That is illustrated in FIG. 14, and FIG. 15 shows an alternative where a two-legged clip is used together with a separate inlet that acts as a second separate branching substrate.
The combined clip and valve of FIG. 14 of U.S. Pat. No. 4400579 mi
REFERENCES:
patent: 4648924 (1987-03-01), Nolf
Nolf Jean-Marie E.
Wambeke Alain
Bryant David P.
Burkard Herbert G.
Raychem Corporation
Rosenbaum Mark
Zahrt II William D.
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