Note: Descriptions are shown in the official language in which they were submitted.
106Z896
This invention relates to the production of multi-
stranded electrical cables and more par-ticularly to filling
the interstices of such cables with powder.
Multi-stranded electrical cables are filled with powder
for water blockage. A powder filling for this purpose is des-
cribed in United States Patent No. 4,002,819 issued January
11, 1977 to NorthernTelecom Limited assignee of Leo V. Woytiuk.
One methlod of filling the interstices of the cable is by passing
the cable core through an electros-tatic powder chamber as des-
cribed in United States Patent No. 4,100,002 issued July 11,
1978 in the name of Leo V. Woytiuk assignor to Northern Telecom
Limited. Such a method is relatively difficult to operate to
obtain fine adjustments in the amount of powder filling placed
within the interstices of the cable, i.e. the percentage of
voids filled by the powder.
It is an object of the present invention to provide an
improved method and apparatus for powder filling a multi-
stranded cable.
Essentially the invention consists of a device for filling
the interstices of multi-stranded cable with powder, comprising:
a cylindrical housing;
a tube within the housing for receiving the multi-~t~anded
cable, the tube being concentric with the housing and spaced
inwardly therefrom to form an annular chamber between said
housing and tube, the tube further being flaired outwardly on
the inlet end thereof and having openings annularly disposed
therein adjacent said inlet end, the chamber being closed at
each end thereof and opening annularly into the tube via said
openings;
powder feeding means opening into the housing; and
means intermediate the housing and tube to move powder
from the powder feeding means from the chamber and into the tube
through said openings to the interstices of the multi-stranded
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cable.
Example embodiments of the invention are shown in
the accompanying drawings in which:
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Figure 1 is a side view i.n cross-section of a device
for powder filling a cable;
Figure 2 is a view similar to Figure 1 showing one
alternate embodiment of the device;
Figure 3 is a view similar to Figure 1, with the cable
omitted, showing another alternate embodiment of the device; and
Figure 4 is a cross-sectional view taken along line 4-4
of Figure 3.
The example embodiment shown in Figure 1 of the drawings
consists of a cable filling device 10 having a cylindrical
housing 12 and a coaxial tube 14 spaced inwardly from the housing
to provide an annular chamber 16. Tube 14 flares outwardly
adjacent its inlet end 18 to meet the end of housing 12 and to
close one end of chamber 16. A circumferential row of parallel,
spaced slots 20 is located in tube 14 adjacent inlet end 18.
A helical screw member 22 is located in chamber 16 with
one end terminating adjacent slots 20. The end of screw 22
remote from slots 20 is fixed to an annular hub 24 of a gear 26
which is coaxial with housing 12 and tube 14. Gear 26 meshes with
a drive gear 28. Hub 24 closes chamber 16 at the outlet end
30 of tube 14 and the hub is freely rotatable axially on the
tube. Powder feeding means in the form of a hopper 32 is
mounted on housing 12 and opens laterally into chamber 16
adjacent hub 24 through an aperture 34 in the housing.
In the operation of the example embodiment shown in
Figure 1 a core 40 is continuously fed axially through tube 14
from inlet end 18 to outlet end 30 of the tube. At the same
time a number of conductors 42 are fed into inlet end 18 of
tube 14, for example from a multi-cage strander, and spirally
J wound on core 40. A powder mixture 43 of predetermined blend
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is passed in a continuous flow, or as needed, into hopper 32
from an inlet conduit 44. The powder Erom hopper 32 passes
through aperture 34 in housing 12 into chamber 16 and is carried
forward in the cham~er by the axial rotation of helical screw
22 which is driven by gear 28 through gear 26. As the powder
mixture reaches the end portion of chamber 16 adjacent inlet
end 18 of tube 14 it passes through slots 20 in the tube and
onto core 40. The lateral m.ovement of conductors 42 as they
are wound about core 40 assists in the movement of the powder
10 against the core.
The amount of powder applied to core 40 is governed
by the speed of travel of the core, the size of slots 20, the
speed of axial rotation of helical screw 22 and the pitch of
the screw. The application of the powder to core 40 is aided
by sloping slots ~ with respect to the axial plane of tube 14
and in the direction of the slope of conductors 42 as seen in
Figure 1.
In the alternate example embodiment of the device
shown in Figure 2 of the drawings slots 20 in tube 14 of the
20 previous example embodiment are replaced by an annular opening
50 which allows greater access of powder from chamber 16 onto
core 40 (tube 14 would be suitably supported by bars not
shown). Also, hopper 32 of the previous embodiment is mod-
ified to provide a fluidized bed of powder. In the embodiment
of Figure 2 a hopper 60, opening onto housing 12 through
an aperture 61, has a porous side wall 62 circumscribed by an
annular housing 64 forming a plenum chamber 66 with an air
inlet 68. Side wall 62 is connected with a vibrator lndicated
schematically by numeral 70.
~0 In the operation of the embodiment of Figure 2
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powder flows into hopper 60 from a conduit 72, either contin-
uously or intermittently,as required to keep the hopper filled.
Air is introduced under pressure through inlet 68 and passes
from plenum chamber 66 through porous wall 62 into hopper 60.
At the same time hopper 60 is oscillated by vibrator 70 and
powder within the hopper forms a fluidized bed 74. This
activated state of the powder mixture facilitates its movement
through chamber 16 and onto core 40.
In Figures 3 and 4 the further alternate embodiment
consists of a tube 80 flaring outwardly at its inlet end 82
with a circumferential row of parallel, spaced slots 84 located
in the wall of the tube adjacent its inlet end. A circulax
housing 86 circumscribing tube 80 adjacent inlet end 82 defines
a chamber 88 which contains a spiral feeder 90 fixed on an
end plate 92 having a collar 94 projecting outside the housing
and carrying an annular gear 96 engagable with a drive gear
98. A hopper 100 opens through an aperture 102 in housing 86
into ~hamber 88. As in the previous embodiment, hopper 100
has,a porous side wall 104 circumscribed by an annular housing
106 forming a plenum chamber 108 with an inlet 110. Side wall
104 is connected with a vibratsr 112.
In the operation of the embodiment shown in Figures 3
and 4 powder is introduced into hopper 100 through a conduit
114 as required to keep the hopper filled. Vibrator 112
oscillates hopper 100 and air under pressure enters through
porous wall 104 to form a fluidized bed 116 of powder in the
hopper. As a core passes into tube 80 through inlet 82 together
with a plurality of s~rands to wrap the core, spiral feeder 90
is rota~ed by drive gear 98. To clarify the structure of
Figures 3 and 4 the core and strands have been omitted but
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they pass through tube 80 in the same manner as in the
previously described embodiments. Powder from hopper 100
passing though aperture 102 of housing 86 into chamber 88 is
picked up by feeder 90 and moved towards slots 84 as the spiral
feeder rotates, finally being forced through slots 84 onto
the core within tube 80.
It will be appreciated that the core and strands
shown in Figures 1 and 2 of the drawings are only illustrative
and other types of multi-stranded cable may be powder filled
by the device of the invention.
It will also be appreciated that types of mechanisms
for driving helical screw 22 may be employed other than meshing
gears 26 and 28; for example a worm gear and screw, a belt and
pulley, or a chain and sprocket may be used.
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