Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to apparatus for stranding
wires.
It is known that the stranding of wires together
offers physical and electrical advantages when the wires are
individully insulated conductors as used in communications or other
electrical systems. For example, the stranding of pairs of wires as
used in telephone systems improves electrical characteristics such
as reducing crosstalk.
Conventionally, to continuously strand wires together
in the same direction requires a heavy rotatable construction as the
wire spools for feeding wire into the appartus must also revolve
about the machine axis. The excessive weight of the construction
limits the operational speed. In order to avoid the rotation of the
spools, a periodically reversing stranding operation is performed
upon the wires and as it is desirable to strand long lengths of
wires in each direction, accumulators become necessary.
In order to overcome problems with known stranding
apparatus, simpler apparatus has been devised to give a periodic
reverse stranding operation. This simpler apparatus as described in
United States Patent No. 3,910,022 granted October 7, 1975 in the
name of Phillip John Reed and entitled "Apparatus For Stranding
Wires" involves the use of a tubular member, one end of which is
held stationary and the other torsionally twisted first in one
direction and then the other around its longitudinal axis. Dividers
positioned along the member divide the tube passage into separate
paths for wires passing down the member. A twisting means at the
downstream end of the tubular member twists the member by rotating
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the downstream end of the member for a predetermined number of
revolutions, first in one direction and then the other, to
torsionally twist the member in reversing manner. A twist is
imposed upon each wire by the twisting means and this twist causes
the wires to strand together along their lengths as the wires emerge
from the twisting means
In United States Patent No. 4,325,214 granted April
20, 1982, in the name of Bretislav Pavel Zuber and entitled
"Apparatus For Stranding Wire", there is described an improvement to
the Reed construction. In this patent, the tubular member is
replaced by an elongate member which is held stationary at an
upstream end and is rotatable at the downstream end for twisting it.
The member has a plurality of wire guiding elements extending
radially outwards from it, each element having wire guiding holes
whereby the wires are threaded through the holes from guiding
element to guiding element while being located outwards from the
elongate member. While the operation of the apparatus described in
the above patents are satisfactory, it has been found that there is
a drag created upon the wires as they pass along their feedpaths and
this drag affects the speed of throughput of the wire. This drag is
created by the contact by the wires with the spaced-apart wire
guiding elements or the dividers, as the case may be.
An object of the present invention is to provide an
apparatus for stranding wires in which the above problem is
minimized.
Accordingly, the present invention provides an
apparatus for stranding wires comprising:-
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a) a single tube defining a single axial passage whichprovides at least two side-by-side feedpaths for wire along the
passage, the passage shaped to prevent wires from moving from
feedpath to feedpath, the tube being rotationally flexible about an
axis to torsionally twist the tube and thus the passage around said
axis from an untwisted position so as to cause the feedpaths to
follow a helical path around the dXis;
b) holding means to hold the tube against rotation about
said axis at an upstream position of the tube;
c) wire twisting means at the downstream position of the
tube to torsionally twist the tube, the twisting means rotatable
with the downstream part of the tube, said feedpaths extending
through the twisting means;
d) rotating means for rotating the twisting means
together with the downstream part of the tube for a predetermined
number of revolutions about the axis alternately in one direction
and then the other;
e) direction changing means to change the direction of
rotation of the twisting means after the twisting means has rotated
0 the predetermined number of revolutions in each direction; and
f) resilient means associated with one of the ends of
the tube to enable movement of said one end in the axial direction
during twisting and untwisting of the tube.
In the above construction, the tube may be a flattened
tube having an elongated passage in a cross-section laterally of the
axis. The elongate passage is of sufficient size at each side of
the passage to allow a wire to pass through it, but merely creates a
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clearance between the wall of the tube and each wire whereby the
width across the flattened portion of the tube is insufficient to
enable the wires to interchange their positions. In another
arrangement, the tube may be formed from two longitudinal sections
each being formed in arcuate shape and in a generally 'U'
configuration with the ends of the 'U' being closer together than a
space defined within the 'U'. Hence, with the free ends of the two
sections being joined together, two spaces are provided by the two
sections with a restriction in between them caused by the narrowing
together of the free ends of the 'U' shapes. With a wire passing
down each tube section of the correct size for the tube, the size of
the restriction is insufficient to enable one wire to pass from one
side of the tube to the other.
Embodiments of the invention will now be described by
way of example, with reference to the accompanying drawings in
which:-
Figure 1 is a side elevational view partly incross-section of apparatus according to a first embodiment;
Figure 2 is a cross-sectional view taken along line
'II-II' in Figure 1 and on a larger scale;
Figure 3 is a cross-sectional view similar to Figure 2
and of a second embodiment.
The apparatus as shown in Figures 1 and 2 comprises a
tube 10 formed from stainless steel or from an acetal homopolymer as
sold under the Trademark "DELRIN". The tube is of generally figure
eight shape in that it has a passage which in cross-section, is
wider at each side than along the centre where there is a
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restriction 14 in the width of the passage. Each side 15 of the
passage provides a feedpath for an insulated electrical conductor or
wire 12. The tube is formed from two partly circular, arcuately
formed, longitudinally extending strips 16 of the material of the
tube and these strips have been joined along their center line in
any suitable manner, such as by metal joining or plastic joining
methods. As may be seen from Figure 2, the restriction 14 to the
passage is formed because each strip 18 extends for an angle greater
than 180 around a center of its arc so that each arcuate shape is
generally U-shaped with the free ends converging.
The tube is disposed within apparatus to extend along
a feedpath for two wires 12 which are to be fed from spools 22. The
tube is held at its upstream end by a holding means to hold the tube
against rotation. This holding means comprises a tube support plate
24 which carries the upstream end of the tube 10 in a complementary
ho1e formed within the plate. The plate 24 is slidably received in
the axtal direction of the tube upon two parallel guides 26 which
are mounted in an upstream position to a fixed frame member 28. By
this means the plate 24 is movable in the axial direction of the
tubes. The plate is resiliently urged towards the frame 28 by means
of two tension springs 30 extending between the plate and the frame
as shown by Figure 1. The springs 30 are superposed one upon the
other in Figure 1, whereby only one spring is shown.
At the downstream end of the tube 10, a twisting means
is provided for twisting the tube alternately in one direction and
then in the other about a longitudinal axis which lies substantially
centrally of the cross-sectional tube shape in Figure 2. This
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twisting means co~prises a cylinder 32 with a hole formed to
securely receive the downstream end of the tube. Two annular
electric clutches 34 and 36 have their driven sides secured to the
cylinder for driving the cylinder alternately in opposite
directions. Each clutch is drivable by a drive belt 38 continuously
driven by an electric motor 40 which forms a rotating means for
rotating the cylinder 32. Upon rotation of one clutch or the other,
the cylinder is rotated in one direction thereby carrying the
downstream end of the tube with it around the axis of the tube. As
the upstream end of the tube is non-rotatable, then any rotation of
the downstream end imposes a twist upon the tube. Alternately, if
the other clutch is operated, then the rotation of the downstream
end of the tube and thus the twist, is in the opposite direction.
The operation of the clutches and motors is such that the downstream
end of the tube is rotated first in one direction about its
equi1ibrium untwisted position and then in the opposite direction.
The design and material of the tube are such that the tube is at
least capable of completing thirty-five revolutions in each
direction from its equilibrium position for a satisfactory working
period without tube failure.
A direction changing means 42 is provided and this is
1ocated at a short distance downstream from the upstream end of the
tube as shown in Figure 1, i.e. at a position in which the tube
rotates less than 360 around its axis for the maximum amount of
turns, i.e. seventy turns at the downstream end of the tube. This
direction changing means is, in fact, located at a position in which
the tube turns only 90 in each direction for the thirty-five
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rotations at its downstream ends at each side of the equilibrium
position shown in Figure 1. This direction changing means is of
similar construction to that described in copending Canadian patent
application No. 409,974, titled "Apparatus For Stranding Wires" in
the names of John Nicholas Garner, Jean Marc Roberge and Norbert
Meilenner, filed concurrently with this present application.
Briefly, the direction changing means comprises two U-shaped heads
44 and 46, each head carrying a magnet in one leg of the U for
creating an electric field and inducing an electric current into a
coil in the other leg. Each coil sends signals into an electric
circuit (not shown), the strength of the signals dependent upon the
strength of the magnetic field. The changing means also comprises a
trigger device for interrupting the magnetic field around each
magnet and this trigger device comprises an interrupter arm 48 shown
in Figur~ 1. This interrupter arm is securely attached to the tube
10 as shown by Figure 2 so as to be rotated by it. The arm is in
radial alignment with the gap within the U of each head 44 and 46 so
as to move into the gap as rotation proceeds, Upon one of the
clutches 34 or 36 rotating the downstream end of the tube in one
direction, the interrupter arm rotates with the tube until it moves
1nto a gap in one of the heads (e.g. head 46). Upon the arm
reaching this position, it interrupts the magnetic field at that
head and causes a change in the induced electric current into the
coil. This causes a change in signal produced in the electric
circuit. This change in signal effects de-energization of one of
the clutches and immediate energization of the other whereby the
rotational direction of the tube is simultaneously changed. Upon
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the tube rotating in the opposite direction, the interrupter arm
moves around and eventually within the gap of the other head 44.
The direction of rotation of the tube is again changed in the manner
described for head 46. Hence, the downstream end of the tube is
rotated for a predetermined number of revolutions alternately in one
direction and the other as controlled by the direction changing
means. The direction changing means 42 differs from that of the
application entitled "Apparatus For Stranding Wire" in that the arm
42 rotates through a different angle, i.e. 90, between the heads 44
and 46. Also, no damping means is provided as in the referred to
application. Such damping means is found to be unnecessary with a
tube of the construction of tube 10.
In use of the apparatus described in the first
embodiment, the insulated conductors are passed one into each side
of the tube, as shown in Figures 1 and 2, and pass along the tube
and out through the cylinder 32. Upon rotation of the downstream
end of the tube alternately in one direction and then the other for
the predetermined number of revolutions, the conductors are twisted
so as to strand together after leving cylinder 32. Twist applied to
the tube effects a twist in the passage and prevents the conductors
from twisting together upstream of cylinder 32. ~lowever, a
separation tube may extend downstream from the cylinder 32 to
prevent the wires from stranding together until they reach a
downstream position from the cylinder.
As can be seen from the above description, the use of
individual dividers or wire guiding elements is avoided in that the
tube provides a continuous guide for each wire as it passes along
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it. It may be seen that the wires do not contact occasional guiding
e1ements, therefore, with their attendant small and intermittent
surface areas of contact. Instead, the continuous contact with the
tube provides less pressure against the surface of the wire whereby
any drag effect is minimized from that obtained with apparatus
according to the prior application and patent as discussed.
In addition, because the two feedpaths within the tube
are provided by a single passage with a restriction along its
center, then each feedpath or part of the passage is open towards
one side, i.e. towards the center of the tube, and at this position
the wire is not contacted by the tube surface. In effect, this
means that there is less area of contact by the tube at this
position and thus the drag is further reduced. The wires may, in
fact, touch across the restriction 14 if the design of the tube is
such as to allow this to happen.
Because of the reduction in drag, the tube 10 with a
length of 80 feet is capable of passing and twisting wires at a
speed in excess of 500 feet/minute to result in stranded wires
having approximately 2.9 inch pitch for thirty-five to forty
rotations of the downstream end of the tube to each side of its
equilibrium position.
In a second embodiment as shown in Figure 3, in
apparatus which is otherwise as described in the first embodiment,
the tube 10 is replaced by another tube 50 which, as shown, is a
single tube which has been passed through a flattening apparatus to
provide two substantially flat and parallel portions 52. In other
words, the tube 50 has a widened elongate passage 54 in
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cross-section and this passage is of sufficient width to accomodate
a predetermined outside diameter of insulated conductor while
providing sufficient clearance to enable it to pass through the
tube. This passage 54 will not allow two insulated corlductors to
interchange their positions so long as the conductors are of a
suitable size to pass through the passage as has just been
discussed. In a preferred arrangement with a construction of this
type and to prevent the wires from becoming jammed within the
passage, it would be sufficient for the passage to provide a
su~ficient clearance around each wire for free running along its
feedpath.
The construction described in the second embodiment
has the same advantages as discussed for the first embodiment.
