Note: Descriptions are shown in the official language in which they were submitted.
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
or 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,
to the preformed tubular sleeve may first be rolled, folded
or otherwise 1.ayered 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~ folded 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
m~,;ber projects from or terminates a~jacent one end of
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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 this 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
3o its other end until the elongate member a~uts 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
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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.
~ eferring to Figure 1 of the drawings, there
is shown a tubular insulating sleeve 10 and a rigid
tubular carrier 12 disposed within the sleeve 10, mid-way
along its length. The carrier 12 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 12 has an outer diameter
greater than the nominal inner diameter of the insulating
sleeve 10 so that it is resiliently embraced or gripped
by the latter. The carrier 12 may be inserted int;o the
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sleeve ~0 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 oE the sleeve
10, so that the sleeve end portion resilien-tly embraces
or grips the mandrel: this operation is easy to eff'ect
manually. Then an elongate element 16 is inserted into
and through the sleeve from its opposite end until (as
shown) this elongate element 16 abuts the mandrel 14:
the elongate element l6 has a diameter less than the
internal diameter o:E 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 elon 7
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element 16 resting on the ground, the sleeve is by manual
action progressively rolled upon itself, startinK from
its upper end which is engaged on the mandrel: Figures
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 16 (see Figure 2a) where the rolled up
portion of sleeve resiliently grips this element 16 (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. Figure 2b),
and it is found that the unrolled portion, together with
the carrier 12, slides progressively along the element
16 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 ~6 is formed with a collar
18 pro~iding 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 12 comes to rest against this stop iust as
the "roll" reaches the rear (upper) end of the carrier:
the carr-ier is thus brought to a stop and a final manual
roll of the sleeve places the "roll" around the carrier
itself (Figure 2a). In the example shown, where the
carrier is mid-way 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
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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 a:Long 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 ha~ing 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 16,
; 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 16
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
vr 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
aIon~ that cable until its leading end reaches the
required point: once the cable is then jointed or
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termina-ted, the sleeve can simply be unrolled into
position over the jointing or terminat:ing ~one.
:tf the carrier is required for assistance in
applying the sleeve but is not required in the eventual
S 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 12 (into the insulating sleeve 10) on site
rather that 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 Figure 2. Then the carrier 12 is
slipped over the element 16 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 16 to limit the travel
f 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 eler,~ent 16 and abuts the
ground .
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Figures 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 26,26 are mounted between these end plates.
A sliding block 2~ 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 ~econd pneumatic actuator 38, the cylinder of which is
ixed 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 3~a,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-clisposed carrier 12. 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
withir, soc~et member 42.
In operation of the machine shown in Figures
3 and 4, the sleeve 10 (with or without its carrier, as
required) is slipped freely onto the rod 40, which is of
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a smaller diameter than the internal d:iameter of the
sleeve 10 (and of the carrier). In order to facilitate
this step, the rod 40 ma~ 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 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 lnterconnected 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 the 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 len~th of travel of the arms, they
are disengaged from the partly-rolled sleeve (b~
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 descrihed with
reference to ~igures 1 and 2 of the drawings. The spring
~4 provides for a degree of resilient displacement of
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the rod 40 (and hence of the partly-rolled portion of
sleeve~ because this embraces the rod 40), counter-
balancing the force applied by the rolling ar~ls 34,34.
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