CA1158025A

CA1158025A - Sleeve-like fitting

Info

Publication number: CA1158025A
Application number: CA000387916A
Authority: CA
Inventors: Michael Still
Original assignee: Kabelmetal Electro GmbH
Current assignee: Kabelmetal Electro GmbH
Priority date: 1980-10-15
Filing date: 1981-10-14
Publication date: 1983-12-06
Also published as: FR2492180A1; DE3038922C2; DE3038922A1; IT1142834B; BE890711A; GB2085538A; JPS5795124A; IT8149371A0; FR2492180B1; SU1153850A3; GB2085538B

Abstract

ABSTRACT OF THE DISCLOSURE
A sleeve made of heat-shrinkable, cross-linked polyethylene is axially split along a thickened wall portion. The two edges thus formed are each provided with alternating teeth and notches in a configuration which allows mating of the teeth of each edge with the notches of the other. The teeth are provided with one or two bores extending axially along the sleeve.
With the edges interengaged, the bores are aligned and a pin or pins can be inserted to fasten the edges together. The pin or pins are retained in the bores upon heat-shrinking the sleeve onto a cable joint.

Description

l 1580~
The prcsent invcntion rclates to a hose-like, tubular fitting for elec~rical cables, tubes, or the like.
A fltting of thc type to wllic}l the invention pertains :is, for example, constructed as a tubular element made of a heat-shrinkable material.
The wall of the fittillg is ~o be cut axially eor permitting lateral slip-on.
~lso, a fastening structure is provided along the line of cutting. Such fittings are, for example, used as connecting sleeves, as termination elements, as covers for splices or other joints between different parts.
The fitting is particularly but not exclusively useful for covering joints in electrical cables. Such a joint may interconnect two very long cables.
If the sleeve does not have an axial cut or slit, it must be slipped onto one of the cables beforehand, and that procedure is easily forgotten. Moreover, sleeves which cannot be slipped onto the point of splicing or joint can be used only for the initial installation, not during subsequent repairs, reconnections, etc.
German patent 15 25 815 discloses a shrink sleeve whose wall is cut along an axial line. ~ metal bar is provided for closing the split joint. The sleeve is provided with protrusions onto which the bar or rail is placed. The particular sleeve is made by extruding a tube or hose, and the material is ~0 cross-linked after the extrusion. The tube or hose has radially inward-oriented protrusions. Suitable lengths are cut from the hose, expanded, and longitudinal-ly cut in between the protrusions. The resulting sleeves are then turned in-side out and installed.
This procedure is cumbersome because the material is relatively stiff and resists change in curvature. The metal rail or bar, when slid over the now outward extending protrusions, must sit thereon very tightly; even still, the sleeve will open occasionally. Particularly, the metal bar may at 1 ~ ~B025 times cut .illtO the protrusLolls; and llpOIl subscquent sllrinking the cut may tear destroyillg the slcevc. ~lso, tho metal rail is to remain on the sleeve after shrinking and may well be regarded as an undesirable latcral protrusion.
It is an objcct of the present invention to provide a new and improved sleeve-like fitting which permits lateral slip-on without undue lateral-ly outwarcl-projecting extensions.
It is another object of the present invention to provide a new and improved heat-shrink sleeve avoiding or lessening the problems of earlier sleeves.
It is a further object of the present invention to provide a new and improved method for making heat-shrink sleeves in such a way that their installation is greatly facilitated.
In accordance with the present invention there is provided a sleeve made of heat-shrinkable material and having a wall portion which is thicker than the remainder of the sleeve wall, the sleeve being axially split along the thicker wall portion so as to define two mutually mating edges each having alternating teeth and notches; the teeth being provided with at least one bore, the bores of the various teeth being aligned; fastening means for being received in said aligned bores to fasten the two edges together; said fastening O means being retained in said bores upon heat-shrinking said sleeve. The fastening means such as a pin is thus virtually embedded and does not constitute an outwardly projecting fastener. The pin stays in position upon application of heat for shrinking. The sleeve, when in situ, will exhibit a slight bulge on the side which includes the pin, but that will amount to a very minor, local, lateral extension which will not interfere with the mounting~ assembly, etc.
It is significant that the closing and fastening of the split

- 2 -I ~ 5 ~ 5 sleeve joint will result predominantly from azimuthally (arcuately~ inter-digitated teeth, and the radial extension of the teeth is selected merely to accommodate tlle inserted pin. The sleeve, though cut axially, is not turned inside out. Particular supplemental features of the sleeve permit its use ~through deformation) to accommodate more than one cable ~at each end).
The sleeve is preferably cut from an extruded tube; the extrusion needs to provide merely a locally thicker wall traversed by one or more bores.
For reasons given below, ridges traversed by bores may also be provided pursuant to the extrusion. Following cross-linking and cutting of the hose into suitable lengths, the resulting sleeves are heated, expanded, and cooled in the expanded state. The thus widened sleeve is then processed by cutting in order to obtain the teeth.
The invention will IIOW be described in greater detail with reference to the accompanying drawings, in which;
Figure 1 is a somewhat schematic side view of a fitting used in a connection between two cables and constructed in accordance with a preferred embodiment of the invention.
Pigures 2 and 3 are respectively front views of two different, sleeve-like fittings shown prior to cutting.
Pigure 2a shows a modified detail on an enlarged scale;
Figure 4 is an azimuthal section view taken through the sleeve of Figure 2, following a teeth-establishing cutting and (temporary) azimuthal separation;
Figure 5 is a front view of an alternatively contoured sleeve prior to cutting;
Figure 6 is a similar view of the sleeve shown in Figure 5 following cutting and fastening of the cut edge;

~ 3 -~ 15~)25 ~ igure 7 is a perspcctive view of a portion of the slecve shown in Figure 5 followine CUtti~lg; and Pigure 8 illustrates the sleevc of Pigure 6, but deformed for an alternative use.
Proceedillg no~Y to the cletailed description of the drawings, ~igure 1 sho~Ys two electrical cables 1 ancl 2 whose ends have been electrically and, to some e~tent at least, mechaniccllly interconnected. Ihe joint is covered by a fitting or sleeve 3 made of a heat-shrinkable and electrically insulating mnterial and having been shrunk onto the insulation of both cables 1 and 2 at 1~ the interco~mected ends thercof.
The sleeve 3 does not have an integrally cylindrical configuration, but its wall has been traversed along a meandering line 4 so that adjacent wall portions can ~e azimuthally separated, and the sleeve can be laterally slipped onto a cable, a cable joint or splice, etc.
The sleeve 3 is made as follows. To begin with, a tube of a suit-able synthetic material such as polyethylene is extruded and the tube is subse-quently cured for cross-linking. The tube may be wound onto a drum for temporary storage and subsequent processing. ~lternatively, the tube is cut immediately into suitable length, i.e., short sleeves having the requisite axial length.
This cutting may be deferred and carried out on the tube as it is reeled from the drum onto which it had been placed for temporary storage.
Nex-t, each sleeve is heated, radially expanded, and cooled again while in the expanded state so that the sleeve now retains its larger diameter.
However, the sleeve retains a "memory" of the initial, smaller d-~mensions while the expanded state is "fro~en" upon cooling. Upon reheating, the sleeve will shrink back to the initial dimensions.
The tube that ls extruded is not of uniform circum~erence. Rather . ~ _ it t~ill h.lve a tl~ick side ~IS can be secll ~roln ~igurcs 2 and 3. In othcr words, the e.~trudcd tub-ll.lr device does not have a uniform wall thickness but a thicker portion. It can be seen, however, that the inncr and outer wall surfaces of the thickened portion 5 of the tube have a smaller curvature than respective "regular" wall surface port:ions. ~ccordingly, the thickened portion 5 does not radially project bcyond tlle outer (geometric) cylinder surface ~efined by the regular outer surface of the sleeve.
Duri.ng extrusion, one or more longitudinal ducts are provided in that thicker portion, such as cluct or bore 6 in Pigure 2 or duct or bores 7 and S in Figure 3. In the case of two ducts, they will run parallel to the central axis of the tube. Instead of just a bore or bores, one may extrude a small tube (6' in Figure 2a) of a mechanically stronger material into the thick wall portion 5 as it is being extruded.
After cutting, the sleeves are heated and expanded radially, e.g., by means of a suitable mandrel, and cooled to freeze the expanded state. This procedure is conventional and does not require elaboration. Next, the fitting sleeve is placed onto - into a punching tool which cuts the sleeve along a meandering line ~4) forming two mating crenated edges. The tool is oriented so that, e.g., in the case of a sleeve as per Figure 2, the resulting teeth 11 ~0 are approximately centrally traversed by the bore 6. This means that the punch-ing is carried out in symmetric relation to an axial line M which coincides with the axis of bore 6. As far as the bore pattern per Figure 3 is concerned, punching along the meandering pattern line is carried out symmetrically to a line (M) that is located half-way in between bores 7 and 8.
After punching, the crenated or toothed edges can be separated azimuthally as far as the sleeve is concerned, i.e., generally along an arc of ~ 5 ~

I ~ ~ B0 25 the circ~unference of the sleeve and as is shown in Pigure 4. T~is, in turn, will permit the sleeve to be laterally slipped over a cable, a splice ~oint, etc., and the teeth 11 can bc ~nade to re-inate or interdigitate. ThIs is depict-ed in ligure 1.
The meandering cut runs through the thickened portion 5 of the slecve, and a first edge portion 9 o the thickened sleeve wall is situated to one side of CUttillg line 4, a second edge portion 10 is on the other side.
~ach one of these edges is, thus, provided ~ith a pattern of alternating teeth (11) and gaps ~12), and the arrangement of the teeth and gaps in the two edges is staggered so that the teeth can interdigitate. Since the sleeve wall was ~minterrupted prior to cutting, it is certain that the respective teeth 11 will fit into the opposite gaps 12. Also, upon establishing this matching fit, all bore increments should be aligned corresponding to the original long bore 6.
A rod or pin 25 is placed into this reestablished bore and fastens the separated portions together. The pin 25 may be a wire or a profiled bar; it is shown with a rectangular cross-section. The profile enhances friction fit of the pin in the synthetic material of the sleeve.
After the rod or pin 25 has been so placed, heat is applied in order to shrink the sleeve onto the cable joint. There is no danger that the material adjacent to the cutting line 4 will rupture. The interior surface of the sleeve may have been coated with an adhesive which becomes active during heating.
This adhesive will not only enhance the fit of the sleeve, but will also seal the axial ends of the sleeve as well as the crenated edges against the cable joint so that moisture cannot penetrate into the splice-affected area under-neath.
In critical cases, it may be advisable to cover the cable joint and and splice underneath the crenated edges, by means of a sealing tape or the 0 2 ~
like, onto wllich the cut portions of the sleeve will shrink while the tape seals the cable joint against ingress of moisture through the cut. The sealing tape may have been covered with such a heat-sealing adhesive in order to bond against the sleeve's teeth from the inside.
It will be appreciated that the fastening procedure compares favor-ably with old methods of inside - out folding of a sleeve, and/or slipping-on of rails. It is important that the fastening pin is embedded in the ridges and these project very little laterally. In the case of a sleeve with two bores (7 and 8), they ma~ be traversed by legs of a U-shaped p-in or hair pin, or by separate pins, for purposes of fastening.
Figure 5 illustrates the front end view of another sleeve. This sleeve has been cut from a tube that had been extruded and has a particular pro-file. Two extensions~ edges or ridges 13 and 14 are separated by a portion 15 of regular wall thickness, and these edges or ridges are traversed by bores 27 and 28. The tube is of relatively wide dimensions. Prior to establishing a meandering joint line, the tube is cut asy~netrically along the line 16 so that the portion 15 now becomes an azimuthally or arcuately extrudedJ flat tongue e~tending from ridge or edge 140 Next, pieces are punched out from ridge por-tion 13 to establish the respective teeth; also~ pieces are cut from ridge portion 14, but not all the way through ~see Figure 7~; rather, the gaps 12' in this case do not penetrate the wall material. In fact, the outer surface of tongue 15 is now extended, and these extensions become lateral boundaries for the gaps 121. Gaps 12' are, of course, situated in complementary locations as far as the newly cut teeth of edge or ridge 13 are concerned so that the edges or ridges 13 and 14 can be made to interengage and interdigitate as shown in Figure 6.
The dimensions are chosen so that the portions of bores 27 in the - 7 ~

respcctive teeth o~ cdge or ridge 13 and portions of borcs 28 remaining in edge or ridge 14 become aligned; and agairl, a pin will traverse the aligned bores in the teeth to lock and ~asten the rid~es 13 and 14 together. The tongue lS clearly covers the cable port;ons under the intergaged teeth. The top (and, possibly, the bottom) of that tongue as extendcd into the region be-tween the teeth 11 of ridge 14 is preferably covered with an adhesive that becomes effective upon application o~ heat to, -thereby, seal t~e teeth against the interior of the sleeve.
The sleeve may, oE course, be used to cover just a portion of a cable or a joint between two cables. The sleeve, however, is flexible and can be used to cover two cables on each end. ~or this, extensions 17 are provided in diagonally opposite locations, rotated ~0 with respect to the completed alignment axis of bores 27 and 28 when the teeth interengage.
The ridges or extensions 17 are provided with axial bores 18 res-pectively. As shol~n in Figure 8, the sleeve is now deformed so that the inside surface portions of the ridges 17 abut and are secured together by means of a suitable hair pin whose legs traverse the bores 18. This deformation is, in effect, retained, and the sleave is now deformed into a figure "8'l pattern.
Consequently, one generates two integral sleeves 20 and 21 in this fashion.
Upon shrinking these two subsleeves each grip tightly about one of two cables on each end.
It can readily be seen that this concept can be extended to have a single sleeve cover from each end more than two cables. The sleeve just has to be sufficiently large ~diameter~, and there must be appropriately located extension ridges 17, to be fastened together in pairs in analogous fashion.
The thickened wall portions of the sleeve are shown in the Figures 5 and 6 to extend radially inward as well as outward. In other words, the outer 1 ~5~25 ~s ~ell as the inner surface contour o~ ~he sleeve deviates a little from the circular. This, howevcr, is not essential; the wall thickness may extend radially inward or outw.lrd only, the respect:ive other surface thcn bcing a cir-cular cylinder. Thc sleeves as per Pigure 2 and 3 show a flat radial inward indentation of the sleeve as a whole so that, ultimately, hardly any portion of the sleeve extends radially outward.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED AS FOLLOWS:

1. A sleeve made of heat-shrinkable material and having a wall portion which is thicker than the remainder of the sleeve wall, the sleeve being axial-ly split along the thicker wall portion so as to define two mutually mating edges each having alternating teeth and notches; the teeth being provided with at least one bore, the bores of the various teeth being aligned; fastening means for being received in said aligned bores to fasten the two edges together;
said fastening means being retained in said bores upon heat-shrinking said sleeve.

2. A sleeve as in Claim 1 in which the teeth extend predominantly arcuately.

3. A sleeve as in Claim 1 in which each tooth has two bores so that two sets of aligned bores result.

4. A sleeve as in Claim 3 in which the fastening means is common to said two sets of bores.

5. A sleeve as in Claim 4 in which the fastening means is a hair pin.

6. A sleeve as in Claim 1 in which the fastening means is a single pin.

7. A sleeve as in Claim 1 in which each bore is lined with a material different from the material of the sleeve and having greater strength than the material of the sleeve.

8. A sleeve as in Claim 1, including additional axial ridges respec-tively having axial bores.

9. A method of making a heat-shrinkable fitting, comprising: extruding a tube having a portion of its wall thicker than the remainder of the tube wall the thicker wall portion having at least one axial bore; causing the tube to cross-link; cutting sleeves off the tube; heating and expanding the sleeves radially and causing an expanding sleeve to cool into an expanded state; axially cutting the sleeve in order to obtain two mutually mating edges each having teeth and notches whereby bore portions in the teeth of one edge align with bore portions in the teeth of the other edge when the edges are mutually mated.