GB2144516A

GB2144516A - Jointing or terminating electric cables

Info

Publication number: GB2144516A
Application number: GB08411829A
Authority: GB
Inventors: Colin David Hillyard
Original assignee: Prysmian Cables and Systems Ltd
Current assignee: Prysmian Cables and Systems Ltd
Priority date: 1983-08-02
Filing date: 1984-05-09
Publication date: 1985-03-06
Also published as: BR8403934A; IT8422096A0; GB2144516B; FR2550395A1; GB8320822D0; IT1176505B; GB8411829D0

Abstract

A tubular insulating sleeve is prepared ready for fitting to an electric cable (for jointing or terminating that cable) by inserting an elongate member 16 into the sleeve so that the elongate member 16 projects from or terminates adjacent one end of the sleeve (e.g. abutting a mandrel 14), the elongate member 16 being of smaller diameter than the internal diameter of the sleeve: then the sleeve is progressively rolled upon itself, starting from its said one end, the rolled up portion of the sleeve gripping member 16 and the remainder portion of the sleeve being free to slide along member 16. A tubular carrier 12 may be disposed within the sleeve before the rolling process, the carrier 12 sliding on member 16 as the rolling progresses and the roll finally being rolled onto the carrier: successive stages in the rolling process are shown at (a), (b) and (c) in the drawing. <IMAGE>

Description

SPECIFICATION Jointing or terminating electric cables This invention relates to jointing or terminating electric cables.

Our United Kingdom patent application No.

81.17023 (Serial No. 2099638A) discloses a method of jointing electric cables or terminating an electric cable, wherein the joint qr termination insulation comprises one or more insulating layers each consisting of a preformed tubular sleeve of elastic insulating material fitted over the cable joint or cable end respectively. In that method, the preformed tubular sleeve may first be rolled, folded or otherwise layered upon itself, then fitted over one of the cables (or the one cable) and finally unrolled, unfolded or unlayered so as to cover the required zone of the joint or termination: the sleeve may first be rolled, filded or layered onto a tubular carrier to facilitate fitting over the cable.

We have now devised improvements in preparing the tubular insulating sleeve ready for fitting to the cable.

In accordance with this invention, there is provided a method of preparing a tubular insulating sleeve ready for fitting to an electric cable for jointing or terminating that cable, comprising inserting an elongate member into said sleeve so that said elongate member projects from or terminates adjacent one end of the sleeve, said elongate member being of smaller diameter than the internal diameter of said sleeve, and then progressively rolling the sleeve upon itself, starting from said one end of the sleeve, the rolled up portion of the sleeve gripping the elongate member and the remainder portion of the sleeve being free to slide along said elongate member.

In practice during the rolling process, it is found that the unrolled portion of the sleeve slides progressively in the direction of rolling but, because it is free to slide in ths manner, it is relieved of stresses which might otherwise serve to resist its rolling and indeed relatively little force is required to effect the rolling.

The method may be carried out manually or using a machine which we have devised.

Thus, also in accordance with this invention, there is provided a machine for carrying out the method, which machine comprises an elongate member for receiving the sleeve to be rolled, a gripper arrangement for frictionally engaging the sleeve, and means for displacing the gripper arrangement lengthwise relative to the elongate member so as to roll up the sleeve by the frictional engagement of the gripper arrangement therewith. For starting the rolling, particularly when the method is carried out manually, an initial step may be employed wherein the end of the sleeve is engaged over an end portion of a mandrel of greater diameter than the internal diameter of the sleeve: then the elongate member is inserted into the sleeve from its other end until the elongate member abuts the mandrel and the rolling is commenced by rolling the sleeve from its end on the mandrel.

Conveniently, a rigid tubular carrier may be disposed within the insulating sleeve, for example mid-way along the sleeve, prior to the rolling process. In this arrangement, the elongate member is preferably formed with a stop against which the leading end of the carrier will come to rest just as the rolling action reaches its rear end: thus a final roll of the sleeve places the rolled up portion of sleeve around the carrier itself. The sleeve with its carrier can then be removed from the elongate member and turned round and the opposite end of the sleeve can be rolled up (and onto the opposite end of the carrier) in like manner.

Embodiments of this invention will now be described, by way of examples only, with reference to the accompanying drawings, in which: Figure 1 is a schematic sectional view of an insulating sleeve engaged over a mandrel and an elongate element in preparation for a manual process of rolling up the sleeve.

Figure 2 shows, at a, b, c, successive stages in rolling up the sleeve manually; Figure 3 is a side view of a machine for rolling up the sleeve; and Figure 4 is a plan view of the machine.

Referring to Fig. 1 of the drawings, there is shown a tubular insulating sleeve 10 and a rigid tubular carrier 1 2 disposed within the sleeve 10, mid-way along its length. The carrier 1 2 may be formed of metal or otherwise rendered electrically conductive (for example it may comprise a plastics material loaded with conductive particles) so that it may remain as a permanent part of an eventual cable joint and serve as an electrical screen over the jointing zone (that is to say over the length of the jointed cables from which the original cable insulation has been removed). The carrier 1 2 has an outer diameter greater than the normal inner diameter of the insulating sleeve 10 so that it is resiliently embraced or gripped by the latter.The carrier 1 2 may be inserted into the sleeve 10 in any simple and convenient manner, for example by placing the sleeve 10 within the bore of an appropriate body which is then sealed to the sleeve at its opposite ends and through which suction can be applied to the exterior of the sleeve, causing it to expand in diameter sufficiently to permit insertion of the carrier 12.

Next a portion at one end of the sleeve 10 is engaged as shown over an end portion of a mandrel 14 of greater diameter than the internal diameter of the sleeve 10, so that the sleeve end portion resiliently embraces or grips the mandrel: this operation is easy to effect manually. Then an elongate element 1 6 is inserted into and through the sleeve from its opposite end until (as shown) this elongate element 1 6 abuts the mandrel 14: the elongate element 1 6 has a diameter less than the internal diameter of the sleeve 10, and is longer.Next, for example and as shown with the mandrel and elongate element vertically disposed and the lower end of elongate element 1 6 resting on the ground, the sleeve is by manual action progressively rolled upon itself, starting from its upper end which is engaged on the mandrel: Figs. 2a, 2b, 2c show the successive stages in this operation.

Firstly in rolling up the sleeve from its upper end, it transfers from the mandrel and onto the elongate element 1 6 (see Fig. 2a) where the rolled up portion of sleeve resiliently grips this element 1 6 (the remainder, unrolled portion of sleeve being free to slide along the element 16). As the rolling up proceeds, the "roll" becomes progressively larger (e.g. Fig. 2b), and it is found that the unrolled portion, together with the carrier 12, slides progressively along the element 1 6 in the direction of rolling (i.e. the downwards direction): because it is free to slide in this manner, the sleeve is free from stresses (particularly in the region of the "roll') which might otherwise serve to resist the rolling, and relatively little manual force is required to effect the rolling.

The elongate element 1 6 is formed with a collar 18 providing a stop, of diameter greater than the internal diameter of the carrier 12 but less than the internal diameter of the sleeve 10. The position of this stop is such that the leading (lower) end of the carrier 1 2 comes to rest against this stop just as the "roll" reaches the rear (upper) end of the carrier: the carrier is thus brought to a stop and a final manual roll of the sleeve places the "roll" around the carrier itself (Fig. 2a). In the example shown, where the carrier is midway along the length of the sleeve 10, the sleeve and its carrier can now be removed from the elongate member and the operation can be repeated on the opposite end of the sleeve, to roll it up onto the opposite end of the carrier.

The carrier can be placed within the sleeve in a factory operation: the rolling-up of the sleeve is preferably and conveniently performed in the field immediately prior to applying the sleeve onto the cable joint or termination.

For example in jointing, the carrier with sleeve rolled upon it can be slipped along one cable, then the cable conductors can be jointed. Next the carrier can be slid along until it is centrally disposed over the joint, to form an electrical screen in the completed joint.

Finally, the sleeve can be unrolled from the opposite ends of the carrier and onto the respective cables, the sleeve having a natural internal diameter less than the underlying cable diameter.

Before inserting the carrier into the sleeve, the sleeve may itself be disposed within an outer sleeve. Then, in rolling up the sleeves onto the carrier, still using the mandrel and elongate element 1 6, firstly one end of the outer sleeve is rolled along the inner sleeve and onto the carrier and next the corresponding end of the inner sleeve is rolled along the element 1 6 and onto the carrier, and next the assembly is removed and turned round for the opposite end of the outer and inner sleeves to be similarly rolled up in turn. In any event, the or the outer sleeve may be formed with an outer skin portion of semiconducting plastics to act as a screen.

If the carrier is not required at all, the sleeve can simply be rolled up by the same technique, either from the opposite ends in turn as described above or more simply from one end to the other, Particularly in the latter case, the roll thus formed can be pushed over the end of a cable to be jointed or terminated, then by a progressive rolling action it can be displaced along that cable until its leading end reaches the required point: once the cable is then jointed or terminated, the sleeve can simply be unrolled into position over the jointing or terminating zone.

If the carrier is required for assistance in applying the sleeve but is not required in the eventual joint or termination but is to be removed instead, then it is disposed at one end of the sleeve and the sleeve is rolled from its other end and onto the carrier: the carrier can then be slipped over a cable to a required point, and the roll of sleeve rolled off it and onto the cable, so that the carrier can be slipped off the cable and the latter then jointed or terminated. Finally the sleeve is unrolled into position over the jointing or terminating zone.

In some cases it may be desirable to insert the carrier 1 2 (into the insulating sleeve 10) on site rather than at the factory. The sequence of steps may then be as follows.

Firstly, the sleeve 10 (with no inserted carrier) is rolled up from one end as described in connection with Fig. 2. Then the carrier 1 2 is slipped over the element 1 6 to abut the roll, and next the sleeve is partly unrolled, being unrolled over the carrier and finishing with the remaining roll disposed at the remote end of the carrier: a stop pin may be inserted through an aperture in the element 1 6 to limit the travel of the carrier during this phase.

Next the pin is removed and the sleeve is rolled up from its other end, finishing with a second roll disposed on the respective end of the carrier. During this final phase the carrier 12 is free to travel along the element 16, but its travel may be limited either by the pin duly re-positioned or by abutting the appropriate end of the element 16 on the ground, the final rolling step ending as the carrier reaches the bottom end of the element 1 6 and abuts the ground.

Figs. 3 and 4 show a machine for rolling up the sleeve, whether or not the carrier is used, and facilitating this process particularly if it is performed in the factory. An elongate base plate 20 mounts upright plates 22, 24 at its opposite ends and a pair of guide rods 26, 25 are mounted between these end plates. A sliding block 28 is mounted for sliding along the guide rods, this movement being powered by a pneumatic actuator 30 which is connected between sliding block 28 and a bracket 32 mounted to the base plate 20.

A pair of elongate arms 34,34 are pivoted by first ends thereof to the sliding block 28 adjacent its opposite ends, the other (or forward) ends of these arms being directed towards the fixed end of the actuator 30 and connected by pivoted links 36,36 to the piston of a second pneumatic actuator 38, the cylinder of which is fixed to the sliding block 28. It will be noted that the actuator 38 and links 36, 36 lie in a plane spaced above the plane of the arms 34, 34. The arms 34, 34 are faced with a strip of friction material along their facing side surfaces 34a, 34a and around their curved forward end surfaces 34b, 34b.

A cylindrical rod 40 is provided for receiving the sleeve 10 to be rolled, which sleeve is shown with a centrally-disposed carrier 1 2.

Adjacent one end the rod 40 is formed with a collar 41 and this end of the rod is inserted into a socket member 42 (mounted to the inner face of the end plate 24) and through an aligned aperture 24a in end plate 24: a coil spring 44 encircles this end portion of the rod 40 and, in use of the machine, acts between the collar 41 on the rod and a shoulder 43 within socket member 42.

In operation of the machine shown in Figs.

3 and 4, the sleeve 10 (with or without its carrier, as required) is slipped freely onto the rod 40, which is of a smaller diameter than the internal diameter of the sleeve 10 (and of the carrier). In order to facilitate this step, the rod 40 may be removed from the machine and then returned to the machine after it has received the sleeve to be rolled. Then actuator 38 is powered such as as to retract its piston into its cylinder and thus acting, via the links 36, 36, to urge the arms 34, 34 towards each other at their forward ends: these ends may be interconnected by a coil tension spring to supplement the force urging them towards each other.Next the actuator 30 is powered to move the sliding block 28 along the machine from the end position which is shown: as a result, the forward end of the arms 34, 34 firstly meet the end of rod 40 and slide along its opposite sides, and secondly they meet the end of sleeve 10. The sleeve 10 is now restrained, by hand, against sliding along the rod 40 under the action of arms 34, 34: as a result, the arms 34, 34 act on the end of sleeve 10 to start rolling up the sleeve from this end. At the end of a certain length of travel of the arms, they are disengaged from partly-rolled sleeve (by extending the piston from the actuator 38) and the sliding block 28 is returned to its end position by extending the piston of actuator 30: then the exercise is repeated to roll the sleeve a further amount. Several repeats of this exercise may be required before the sleeve has been rolled from the one end and onto the corresponding end of the carrier: then the sleeve may be removed from the rod, turned round and re-applied to the rod, so that the other end of the sleeve can be rolled up and onto the other end of the carrier. During each rolling step, the unrolled length of the sleeve is free to displace along the rod, as described with reference to Figs. 1 and 2 of the drawings. The spring 44 provides for a degree of resilient displacement of the rod 40 (and hence of the partly-rolled portion of sleeve, because this embraces the rod 40), counterbalancing the force applied by the rolling arms 34, 34.

Claims

1. A method of preparing a tubular elastomeric sleeve ready for fitting to an electric cable for jointing or terminating that cable, comprising inserting an elongate member into said sleeve so that said elongate member projects from or terminates adjacent one end of the sleeve, said elongate member being of smaller diameter than the internal diameter of said sleeve, and then progressively rolling the sleeve upon itself, starting from said one end of the sleeve, the rolled up portion of the sleeve gripping the elongate member and the remainder portion of the sleeve being free to slide along said elongate member.

2. A method as claimed in claim 1, in which said one end of the sleeve is engaged over an end portion of a mandrel of greater diameter than the internal diameter of the sleeve, and said elongate member is brought to abut said mandrel end-to-end before rolling of said sleeve is commenced from its said one end.

3. A method as claimed in claim 1 or 2, in which a rigid tubular carrier is disposed within the elastomeric sleeve prior to the rolling step, the carrier being a sliding fit on the elongate member, and the rolling step serves to place the rolled up portion of the sleeve around the carrier.

4. A method as claimed in claim 3, in which the elongate member is formed with a stop against which a leading end of the carrier comes to rest just as the rolled up portion of the sleeve reaches the opposite, or trailing, end of the sleeve, a final roll of the sleeve placing its rolled up portion around the car river.

5. A method as claimed in any preceding claim, in which the elastomeric sleeve is rolled up for part of its length from its said one end, and is then turned round on the elongate member and rolled up from its other end.

6. A method as claimed in any preceding claim, in which the elastomeric sleeve is disposed within an outer sleeve before the rolling step, then the outer sleeve is rolled up from said one end before the inner sleeve is rolled up from its said one end to provide separate rolls of the inner and outer sleeves adjacent each other.

7. A machine for carrying out the method of claim 1, which machine comprises an elongate member for receiving the elastomeric sleeve to be rolled, a gripper arrangement for frictionally engaging the sleeve, and means for displacing the gripper arrangement lengthwise relative to the elongate member so as to roll up the sleeve by the frictional engagement of the gripper arrangement therewith.

8. A machine as claimed in claim 7, in which the gripper arrangement comprises a pair of arms and an actuator for pivoting the arms to urge them against opposite sides of the elongate member and elastomeric sleeve.

9. A machine as claimed in claim 7 or 8, comprising a liner actuator for displacing the gripper arrangement lengthwise of the elongate member.

10. A machine as claimed in claim 7, 8 or 9, in which the gripper arrangement, in use, is reciprocated a plurality of times to roll up the elastomeric sleeve from its said one end.

11. A method of preparing a tubular elastomeric sleeve ready for fitting to an electric cable for jointing or terminating that cable, which method is substantially as herein described with reference to the accompanying drawings.

1 2. A machine for carrying out the method of claim 1, which machine is substantially as herein described with reference to Figs. 3 and 4 of the accompanying drawings.