GB2374628A

GB2374628A - Cable clamp

Info

Publication number: GB2374628A
Application number: GB0103557A
Authority: GB
Inventors: Paul Macnamara
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-02-14
Filing date: 2001-02-14
Publication date: 2002-10-23
Also published as: GB0103557D0

Abstract

A clamp (10) for retaining at least two cables in a spaced relationship comprises first and second cable-engaging elements (11, 19) linked together by linkage means (15,18). The elements (11,19) are moveable, about a hinge (13), between an open position and a cable-retaining position, a closure means (22) releasably holding the elements (11,19) in the cable retaining position. The linkage means (15,18) subtend an acute angle with respect to each other to hinder or prevent unwanted opening of the clamp (10). Moreover, the linkage means (15,18) can include a slot (26) to receive and retain the closure means (22). In one embodiment, the closure means (22) is an elongate threaded member, releasably held in position by a loading nut or toggle (23). In order to improve the grip on a cable by the cable-engaging elements (11, 19), protrusions (24) are included on the inner surface thereof to engage the cable.

Description

AN IMPROVED CABLE CLAMP Field of the Invention The invention relates to a clamp for use in maintaining a spaced relationship between two cables. In particular, the clamp is suitable for clamping a subsidiary cable to an umbilical cable, for example, in a sub-sea environment.

Background to the Invention Cables are frequently used to transmit power, information, and materials between two locations remote from each other. Technical fields in which these can be used are for example, building sites, overland power cables, gas and oil pipes and sub-sea work. Frequently, particularly in sub-sea situations where a diver is working on the sea bed, two cables are required. The first of these, often termed an umbilical, conveys air, heat etc. from a mother ship to the diver working on the sea-bed. A second cable is provided to enable data or power to be transmitted to and from the diver and the ship.

These cables are typically linked together using a clamping system to maintain them in close spatial relationship to each other and reduce the risk of entanglement or snagging of one or both of the cables either with each other or on other objects in the vicinity.

Conventional clamping systems are difficult to fix initially in position and to remove when no longer required. Furthermore, the clamping systems frequently cannot withstand the stresses imposed on them in the underwater environment, such as derive from sea currents. The stresses result in the clamp shearing or

deforming, which decreases the efficiency and strength of the clamps and makes the clamps difficult to remove. This delays the de-coupling of the cables which when related to sub-sea work can be expensive and increase risk There is also the disadvantage that the clamps cannot be re-used It is an object of the present invention to provide a clamp which seeks to alleviate the disadvantages associated with the clamp known in the prior art.

For the avoidance of doubt it should be noted that the term cable should also include tubes, pipes, wire etc.

Summary of the Invention A clamp for retaining a pair of cables in spaced relationship, the clamp comprising first and second cable-engaging elements arranged to co-operate with each other, each element comprising a primary cable-receiving portion and at least one secondary cable-receiving portion, the or each portions being held in fixed spaced relationship from each other by a linkage means ; and a closure means arranged to releasably lock the cable-engaging elements together so that each cable-receiving portion of the first element co-operates with the corresponding portion of the second element for securing a cable therebetween The first and second cable-engaging elements are advantageously hingeably linked.

The clamp further including a closure means to releasably retain the first and second cable-engaging elements in a cable-engaging position and so retain the cable in the desired position The linkage means of the first element preferably forms an acute angle with the linkage means of the second element, when the clamp is in the cable-receiving

position to hinder the clamp opening should the closure means become loosened during operation.

The closure means is preferably mounted to the second linkage means, the first linkage means having a slot or other opening to receive and retain the closure means and so hold the two cable-engaging elements of the clamp together. The closure means is preferably elongate and is advantageously pivotally mounted at a first end to the second cable-engaging element, the second end of the closure means passing through the slot.

A retention means advantageously retains the closure means in position. The retention means is preferably a loading nut or toggle, mounted threadably about the closure means, which toggle when tightened presses the two cable-engaging elements of the clamp together. The slot is conveniently wider at one end to receive and allow passage of the retention means.

The cable-receiving portions can include protrusions, such as spot welds, on their inner surface, the protrusions gripping the cable when the clamp is in the cableengaging position.

According to a second aspect of the invention there is provided a method of attaching/releasably linking two cables in spaced relationship to one another, the method including the steps of i) locating a first cable in a first cable receiving portion of a first cable- engaging element of a clamp ; ii) locating a second cable in a second cable receiving portion of the first cable-engaging element of the clamp, the second cable receiving portion being operatively linked to the first cable receiving portion ; iii) engaging a second cable-engaging element of the clamp with the first cable-engaging element to retain the cables ;

iv) employing closure means to maintain the two elements of the clamp in a cable retaining position; and v) tightening the closure means.

Brief Description of the Drawings The invention will now be described with reference to the accompanying drawings which show one embodiment of the apparatus. In the drawings : Figure 1 is an end elevation of a closed clamp ; Figure 2 is a plan view of an open clamp ; Figure 3 is a view of part of the clamp along X in Figure 1, Figure 4 is a view of the clamp along Y in Figure 1; and Figure 5 is a detailed view of a swing bolt.

Detailed Description of the Invention Referring initially to Figure 1, a clamp, generally referenced 10 comprises a first cable portion 11 and a second portion 12. The portions 11,12 are hingeably mounted to each other by means of a hinge 13. The portion 11 comprises a main sleeve 14 having a semi-circular cross-section. A clamp-plate 15 is welded at a first end to the main sleeve 14, the plate 15 subtending an angle of 15 with a line drawn from the centre of the hinge 13 and the centre of the circle on which the main sleeve 14 lies. A smaller sleeve 16, also having a semi-circular cross-section is welded to the second end of the sleeve 14.

The second portion 12 also comprises a main sleeve 17 to which a first end of a clamp-plate 18 is welded The orientation of the clamp-plate 18 is parallel to a line drawn from the centre of the hinge 13 and the centre of the circle on which the sleeve 17 lies. A second smaller sleeve 19 is welded to the second end of the clamp-plate 18.

When the clamp 10 is in its closed position, as shown in Figure 1, the two smaller sleeves 16,19 form a closed circle A V-shaped retainer 20 is mounted to the clamp-plate 18. The retainer 20 houses the cross-piece of a T-bar 22 enabling the T-bar 22 to pivot about the axis through the cross-piece. A rod extends perpendicularly from the cross-piece, and has a threaded outer surface. A loading nut or toggle 23 having a hexagonal crosssection and, having a thread corresponding to that on the T-bar 22, is threadably mounted to the T-bar 22. The T-bar 22 passes through slots 25,26.

In Figure 2, the internal structure of the sleeves 14,16, 17,19 is shown A number of beads 24 are welded onto the surface of the sleeves 14,16, 17,19 which beads project away from the sleeves 14,16, 17,19 and provide an extra grip to a cable enclosed therein. The clamp-plates 15,18 each include a slot 25,26 respectively.

The slot 25 in the clamp-plate 15 has a keyhole shape. The slot 26 in the clampplate 18 is sufficiently long to allow the T-bar 22 to pivot freely within the angle allowed by the V-shaped retainer 20.

In use, the clamp 10 is opened out by swinging the portion 11 in the direction indicated by the arrows A in Figure 1 until the portion 11 reaches the position shown by the dotted lines B. The main umbilical cable from a surface ship is located in the main sleeve 14 of one of the two portions of the clamp 10 by an operator. A subsidiary cable is then located in the smaller sleeve 16 of the same portion 11. The other portion 12 is then pivoted about the main hinge 13 to bring the two portions 11,12 together and surround the two cables As the two portions 11,12 are brought together, the T-bar 22 and toggle 23 are passed through the widest section of the keyhole-shaped slot 26 in the opposing portion 12 as shown by the dotted line in the position C in Figure 1.

When the two portions 11,12 have been brought together, the T-bar 22 and the toggle 23 are pivoted about the hinge 21 to bring the toggle 23 adjacent the narrowest section of the key-shaped slot 26, when it is then in the position D. The toggle 23 is then screwed onto the T-bar 22 to tighten the two portions 11,12 together, and ensure that the clamp 10 firmly grips the cables. The grip on the cable is enhanced by the beading 24 on the cable-gripping surfaces of the sleeves 14,16, 17, 19.

Figure 5 shows a T-bar in more detail. The T-bar 50 comprises a cross-piece 51

from which an elongate threaded member 52 subtends perpendicularly A toggle t, 9 53 having a hexagonal cross-section, has a hole along its central axis, the walls of the hole having a thread complementary to that of the threaded member 52. The hexagonal cross-section enables the toggle to be tightened and loosened either by hand or by means of a machine tool.

The profile of the slot can be more rounded between the widest part of the slot and the narrowest This enables the T-bar to be swung more easily between the closed and the opened position.

The toggle can be chamfered to enable the nut to be held in a spanner bit and driven into the T-bar thread This feature is particularly useful in sub-sea work and cold environments. The T-bar and toggle can also comprise means for reducing the chances of the toggle being lost upon loosening For example, the threaded portion of the T-bar can have a section of the thread missing. The thread of the toggle can also comprise an unthreaded section, such that on unscrewing the toggle from the T-bar, at some point the toggle and T-bar are disengaged from one another, and from an axial force is applied to re-engage the toggle and T-bar threads then the toggle will remain and be held in contact with the T-bar The clamps as described above may comprise a number of additional features which do not depart from the scope of the invention. For example, the beading can be in the form of continuous smooth ridges across the inside surface. Alternatively or additionally the beading can comprise discrete protrusions The protrusions or ridges can be smooth, and so simply reduce the effective diameter of the sleeves to cause the clamp to grip. they can also be sharp to bite in, to a limited extent to the cable.

The clamp can also comprise additional sleeves to retain further cables when so required.

The two portions of the clamp can be initially separate and clipped together in order to hold the cable in position A number of complementary lugs can also be provided which can receive nuts, bolts etc and so hold the two portions of the clamp together.

It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention.

Claims

Claims I A clamp for retaining a pair of cables in spaced relationship, the clamp comprising first and second cable-engaging elements arranged to co-operate with each other, each element comprising a cable-receiving portion for a primary cable and at least one auxiliary cable-receiving portion for one or more secondary cables, the portions being held in fixed spaced relationship from each other by a linkage means, and a closure means arranged to releasably lock the cable-engaging elements together so that each cable-receiving portion of the first element co- operates with the corresponding portion of the second element for securing cables therebetween.
2. A clamp as claimed in claim 1, in which the first and second cable- engaging elements are moveable between open and cable-retaining positions about a hinge.
3 A clamp as claimed in claim 1 or claim 2, in which the closure means releasably locks the first and second cable-engaging elements in a cable- retaining position so as to hold cables in a predetermined spaced relationship.
4 A clamp as claimed in any one of the preceding claims, in which the

linkage means of the first element forms an acute angle with the linkage 1 0 means of the second element, when the clamp is in a cable-retaining position operably to hinder or prevent the clamp opening should the closure means become loosened during operation

<Desc/Clms Page number 9>
5 A clamp as claimed in any one of the preceding claims, in which the closure means is mounted to the linkage means associated with the first cable engaging element, the linkage means associated with the second cable engaging means having a slot or other opening to receive and retain the closure means so as to releasably secure two cable-engaging elements of the clamp together
6. A clamp as claimed in any one of the preceding claims, in which the closure means comprises a first externally threaded elongate element which is pivotally mounted at a one end to the second cable-engaging element and at the other end is adapted to pass through the slot or opening

of the second linkage means 0
7. A clamp as claimed in claim 6, in which the closure means further comprises a retention means which is internally threaded and adapted to engage the elongate element to retain the closure means in position.
8. A clamp as claimed in claim 7, in which the retention means comprises a loading nut or toggle, mounted threadably about the closure means, which nut or toggle when tightened urges the two cable-engaging elements of the clamp together.
9. A clamp as claimed in any one of claims 5 to 8, in which the slot is wider at one end to receive and allow passage of the closure means
10 A clamp as claimed in any one of the preceding claims, in which the or each cable-receiving portion includes protrusions, on the inner surface thereof, the protrusions being so shaped as to grip a cable when the clamp is in the cable-retaining position.

<Desc/Clms Page number 10>
11 A method of linking two cables in spaced relationship to each other, the method including the steps of i) locating a primary cable in a first cable-receiving portion of a first cable-engaging element of a clamp, ii) locating a secondary cable in an auxiliary cable-receiving portion of the first cable-engaging element of the clamp, the auxiliary cable-receiving portion being operatively linked to the first cable receiving portion, iii) bringing a second cable-engaging element of the clamp into operable proximity to the first cable-engaging element to retain the cables ; iv) engaging closure means to maintain the two elements of the clamp in a cable-retaining position, and

v) tightening the closure means n
12. A method of linking two cables in spaced relationship, in which step ii) above is repeated for additional secondary cables in further auxiliary cable-receiving portions.
13 A clamp substantially as herein described with reference to and as shown in the accompanying drawings.
14. A method of linking two cables in spaced relationship substantially as

herein described with reference to the accompanying drawings.

I