Note: Descriptions are shown in the official language in which they were submitted.
1037241 -
Damage to the sheathing of an electric cable presents the danger of
moisture entering the cable and spreading in an axial direction so that a large
cable section may become filled. The danger of axial spreading of moisture,
which penetrates due to damage of the cable sheathing, is particularly pre-
dominant in communication cables having plastic-insulated wires, because these
offer little resistance to the axial advance of moisture. It therefore forms
:
part of the art to provide plastic-insulated communication cables, either cont-
inuously or at intervals, with a moisture barrier which will prevent a further
axial spreading of water penetrated. To this end, a mass resembling petrol '~
jelly, which constitutes a mixture of microcrystalline petrol waxes and oils, '
is inserted into the cable core.
It has become apparent that communication cables which are filled with
a stuffing mass of this kind'may become leaky, in that the space between cable
core and a wrapping applied thereto and/or the space between the wrapping and
the cable sheathing is insufficiently filled with the stuffing material. In
an attempt at overcoming these difficulties, the stuffed cable core may be ~`'
directly enclosed in a thin metallic casing and the cable core be compressed
by means of impressions imparted to the metallic casing at brief intervals
across its entire circumference, thus increasing the proportion of the total
volume of the substance and thereby guaranteeing the longitudinal sealing of
the cable core. This compression of the cable core may, for example, be applied '
to the thin metallic layer by means of stamping wheels, or by means of wave-
shaped stamping, being applied either concentrically, or helically with respect
to the axis of the cable ~German 'Auslegeschrift' 2,028,286). Other devices
which are specifically constructed for the compression process may provide,
for example, at least two rotating moulding tools which are in engagement with
a metallic coating sheathing the cable core. These tools are provided on their '
circumference with a semi-circular groove and with cams therein ~German Utility
Patent 7,044,563), or with two pneumatic cylinders which at their respective
outer ends are provided with a divided ring and which are adapted to effect a
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:- 103 ~
mutual impact at predetermined intervals so that an annular waving of the
` metallic layer is produced (German Utility Patent 7,145,576). Other devices
of the known kind are constructed in such a fashion that they permit the pro-
duction of one or more helically extending grooves which may be applied in
opposite directions. To this end, a rotating tool is provided in a holder
with either one or a plurality of members adapted to press into the metallic
layer, preferably forming part of a so-called stratified sheathing, thereby
forming the grooves. Members for impressing grooves of this kind may have the
configuration of ball-point pins which are radially pressed against the cable
core, or the configuration of balls running off the metallic layer and being
pressed thereagainst by means of a carrier sleeve. The members for impressing
n,
- the grooves are individually adJustable in radial direction so as to adapt the
rotating compressing tool to cable cores of different diameter (German
; ~
'Offenlegungsschrift' 2,152,264 and German 'Offenlegungsschrift' 2,153,622).
According to the invention, there is provided a device for longitud-
inally sealing multi-core plastic-insulated electric cables having a so-called
stratified sheathing by impressing grooves, extending helically about the
cable axis, into a metallic layer of the stratified sheathing which layer is
. ;
directly applied to a substance filling the cable core for affording a longi-
tudinal sealing thereof, said grooves being impressed by means of a tool and
.f means for rotating said tool about the cable core, said tool comprising in a
holder either one or a plurality of members adapted to impress the grooves by
pressing against the metallic layer of the stratified sheathing, and character-
ized in that the members for impressing the grooves are pins which lie tan-
~; gential to the cable and contact the cable at a point intermediate the ends
of the pins.
... . .
In a device of this kind the tangential abutment of the pins results
in a relatively soft or gradual application of force by the members provided
for impressing the grooves in the thin metallic layer which, as a rule, has a
. 3o wall thickness of between 0.1 and 0.3 mm. This soft application of force used
for impressing the thin metallic layer, or sleeve, prevents any damage thereto
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1037Z4~
by the members used~ This applies in particular to uneven surface spots of
the sheathing.
In a further development of the present invention it is advisable to
dispose the pins at an incline to the axis of rotation of the tool. This per-
mits an adaptation of the application of force to the longitudinal movement of
the cable core to be worked. -
In further improving the soft application of force of the pins, it
; is advisable to make them resilient, i.e. to either manufacture them from a
correspondingly resilient material, or to provide them with springs. This
permits a better adaptation of the pins to any unevenness in the thin metallic
layer A resilient positioning of the pins may be ensured, for example, by
holding the pins stationarily at one end, while, at the other end, holding them
; in a manner which permits longitudinal movement. To this end, it is recommend-
ed to provide as holders for each pin, pegs each of which has a bore for guid-
; ing the pin. The pin is firmly inserted in a first peg, whereas the pin is
merely guided by the second peg by means of a bore therein.
` In a particularly advantageous embodiment of this novel device, the
; pegs at the stationary ends of all pins are attached on the segment of a ring
that is concentrically disposed to the axis of rotation of the tool, while the
pegs at the ends that are permitted longitudinal movement are attached on the
segment of a further ring that is concentrically disposed to the first ring.
By means of such an embodiment, the tool may be adapted to allow for both
rotation of the rings relative to each other and free rotation of the peg hold-
~` ers about their axes, thus permitting variation in the depth of the groove and
the accommodation of different cable diameters. When rotating the rings in
,
opposite directions, the groove-forming pins move in the fashion of an iris
diaphragm, either away from the axis of rotation by uniform amounts, or toward
;- the axis of rotation by uniform amounts. The rotation of the rings in opposite
directions may be carried out, for example, by means of a self-locking gear
unit.
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103724~
- The invention will now be described, by way of example only, with
` reference to the accompanying drawing, in which:
Figure 1 illustrates an embodiment of the novel device in schematic
view and Figure 2 illustrates the device in elevation. With the aid of this
embodiment, the invention will be described hereunder in detail.
A device 1J being schematically illustrated in Figure 1, effects
the impressing of helically extending grooves in a thin metallic layer which
is applied as part of a so-called stratified sheathing to a cable core 2
being filled with a substance of the petrol jelly type. The device 1 effects
a compressing of the cable core, in particular in its outer region and thus
a proportional increase of the petrol jelly-type substance in the total volume
of the cable core. The cable core is guided by nipples 3 and 4 while being
worked at by the device 1. The nipples are disposed at either end of the
device. The device comprises substantially two rotating tools 10 and 20,
.. . .
~ adapted to rotate in opposite directions, and impressing in a thin metallic
:; layer of the cable core 2 two oppositely directed helical grooves. The rotary
tools are provided with holders 11 and 21, respectively, which are each providet
with a toothed rim 12 and 22, respectively. Through this toothed rim the tools
are driven at the desired speed by the main drive 18 via an adjustable gear 19.
With the aid of peg-like clamping means 13 and 14, 23 and 24, respect-
ively, there are affixed to holder 11 and 21 resilient steel wires 15 and 25,
. . ~
respectively. In the shorter clamping means 13 and 23, respectively the steel
wires forming the members utilized for imprinting the grooves are clamped in
~ightly, whereas in the longer clamping means 14 and 24, respectively, the
wires are merely guided. This longitudinal guidance in clamping means 14 and
24, respectively, ensures the resilient characteristics of the steel wires 15
and 25, respectively, in radial direction. The different lengths of the clamp-
ing means 13 and 14 or 23 and 24 afford an oblique positioning of the resilient
steel wires 15 and 25 with respect to the rotational axis of the tool.
Figure 2 illustrates details of the rotary tool, being illustrated
-.
.. y,
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`` 10;~7241 .
in Figure 1 in principle. The rotary tool is shown in elevation.
The rotary tool substantially comprises frame 30, inside which are
disposed a rotatable outer ring 31 and an inner ring 33 which is adapted to
rotate together with the outer ring. The outer ring bears peg-shaped clamp-
ing means 32 for pins 35 which are formed by resilient steel wires provided
for impressing the grooves, whereas the inner ring 33 bears peg-shaped clamp-
ing means 34 which permit a movement in longitudinal direction. Both rings
are adapted to be rotated in opposite directions to each other with the aid of
a self-locking gear, comprising a toothed rim 36 being mounted on inner ring
33 and a worm 37 being mounted on the outer ring 31. According to the position
of the outer and inner rings to each other the provided four pins 35 form a
polygon, the sides of which tangentially abut the cable core being guided
through this polygon. By an axial movement of the cable core the rotation of
the tool, comprising the outer ring 31, the inner ring 33 and the pins 35,
impresses helical grooves into the thin metallic layer on the cable core. A
movement of the outer ring 31 against the inner ring 33 with the aid of the
self-locking gear 36/37 permits the rotary tool to be adapted to different ~-
diameters of the cable core and to set different depths of groove in a con-
tinuously variable manner. The four pins 35 of the rotary tool permit the
simultaneous impression of four helical grooves in the thin metallic sheathing
of the cable core. The oppositely adjustable rings are calibrated 38 so that
the setting of the rotary tool on a specific diameter of a cable core can be
read and reproduced.
The outer ring 31 is driven by a studded belt 39 through a drive not
shown in Figure 2.
