[0001] This invention relates to apparatus for stranding wires.
[0002] It is known that the stranding of wires together offers physical and electrical advantages
when the wires are individually 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.
[0003] Conventionally, to continuously strand wires together in the same direction requires
a heavy rotatable construction as the wire spools for feeding wire into the apparatus
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.
[0004] 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 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.
[0005] 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", 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.
[0006] With both of the above structures which are extremely flexible, they have a degree
of uncontrollable lateral movement during use as a result of the twisting forces involved,
and this makes them unsuitable for use in a machine where insufficient lateral clearances
can be provided to allow for such movement.
[0007] In a further construction disclosed in United States Patent No. 3,847,190, there
is disclosed an apparatus for stranding wires comprising two tubes which are mounted
in end housing, the two tubes being twisted together around a common longitudinal
axis to provide twist in wires passed along the tubes. While this construction presents
less lateral movement than in the constructions of Zuber and Reed, it does, however,
suffer from a disadvantage in that the two tubes tighten together during twisting
and untighten during the untwisting operation so as to slacken and move further apart.
This tightening and slackening action changes the degree of drag upon the wires. Apart
from this, because of the method of twisting these two tubes, the tubes do not twist
uniformly from end to end and this results, together with the change in drag, to twisting
of the wires in a non-uniform and smooth fashion.
[0008] The present invention provides an apparatus for stranding wires in which tubular
means is provided having passage means defining feedpaths for at least two wires and
wherein the feedpaths are held in fixed relative positions in at least some locations.
With such a structure, during twisting of the tubular means, relative lateral movement
of the feedpaths is either impossible or is restricted. The only way in which the
twist can be accomodated therefore, is by a change in length of the tubular means
during twisting. This is ensured by the use of a resilient means for placing axial
tension upon the tubular means.
[0009] Accordingly, the present invention provides an apparatus for stranding wires comprising
a tubular means, defining passage means forming at least two feedpaths for wires with
the feedpaths held in fixed positions apart in at least some locations along the tubular
means, the tubular means being rotatably flexible about a common axis to torsionally
twist the tubular means and thus the passage means around said axis from an untwisted
position;
holding means to hold the tubular means against rotation about said axis at an upstream
position of the tubular means, wire twisting means at a downstream position of the
tubular means to torsionally twist the tubular means, the twisting means rotatable
with a downstream part of the tubular means, said feedpaths extending through the
twisting means;
rotating means for rotating the twisting means together with the downstream part of
the tubular means for a predetermined number of revolutions about the axis alternately
in one direction and then the other, direction changing means to change the direction
of rotation of the twisting means after the twisting means has rotated the predetermined
number of revolutions in each direction, and
resilient means associated with one of the ends of the tubular means to enable movement
of said one end in the axial direction during twisting and untwisting of the tubular
means.
[0010] In the above apparatus according to the invention, the tubular means preferably comprises
at least two tubes each defining a passage forming one of the feedpaths. The untwisted
position of the tubular means is one in which the tubes extend axially and lie substantially
parallel. In this two tube arrangement, means is provided to prevent movement towards
each other or apart of the tubes in spaced locations between the tube ends.
[0011] In another structure according to the invention, the tubular means comprises a single
tube formed with two passages which lie side-by-side.
[0012] With the above structure, because the feedpaths are held in fixed positions, in at
least some locations, then there is a more controlled degree of drag movement along
the feedpaths than would be the case if no restraint were used. Also, in the inventive
structure, the degree of drag is less erratic. Because of the prevention of relative
movement of the feedpaths, it is found that twist takes place uniformly from end to
end of the tubular means thus reducing drag.
[0013] Embodiments of the invention will now be described, by way of example, with reference
to the accompanying drawings in which:-
Figure 1 is a diagrammatic side elevational view, partly in section, of apparatus
according to the first embodiment with tubes of the apparatus shown untwisted;
Figure 2 is a view similar to Figure 1 with the tubes twisted and with another part
of the apparatus in section;
Figure 3 is a cross-section through Figure 1 taken along line 'III-III' in Figure
1 and on a larger scale; and
Figure 4 is a cross-sectional view taken along line 'IV-IV' in Figure 2; and
Figure 5 is a cross-section similar to Figure 3 and of a second embodiment.
[0014] The apparatus as shown in Figure 1 comprises two side-by-side tubes 10 formed from
stainless steel or from an acetal homopolymer as sold under the Trademark "DELRIN".
The tubes may be of any length consistent with providing the twist required in wires
to be passed along the tubes. The length of each tube is approximately 70 feet with
an external diameter of 0.22 inches and an internal diameter of 0.075 inches. The
two tubes are rotationally flexible about a common median axis 12 with which they
lie parallel. The tubes also lie parallel to each other in a tube untwisted position
(as shown by Figure 1). The design of the tubes is such that each tube may be rotated
around the axis 12 for a minimum of thirty-five turns each side from the equilibrium
position as shown. Hence, upon alternating the direction of twist of the tubes, the
tubes rotate for seventy turns in each opposite direction before a succeeding change
in direction.
[0015] Each tube defines a feedpath for a wire 14 which is to be passed down the tube for
the purpose of providing a twist in the wire whereby upon issuing from the downstream
end of the tubes, the twist in the wires enables them to automatically strand together.
[0016] The tubes have a means for preventing movement towards each other or apart during
their rotational movement around the axis 12. This movement prevention means comprises
a series of discs 16 which are positioned at spaced intervals along the tubes as shown
in Figure 1. Each tube has two holes 18 as shown in Figure 3 through which the tubes
are passed in close fitting relationship and which hold the tubes in their spaced
apart positions.
[0017] At an upstream end of the tubes there is provided a holding means to hold the tubes
against rotation about the axis 12 at the upstream ends. This holding means comprises
a tube support plate 20 having two holes adjacent its outer periphery upon which the
plate is slidably received in the axial direction upon two parallel guides 22 which
are mounted in an upstream position to a fixed frame member 24. By this means the
plate 20 is movable in the axial direction of the tubes. Each tube is received at
its upper end in bearings 26 in the support plate 20 whereby the upstream end of each
tube is rotatable about its own axis while the tube is being rotated about the axis
12.
[0018] The upstream ends of the two tubes are movable together in the axial direction to
enable a shortening and lengthening of the tubes which is necessary as the tubes twist
together and untwist about the axis 12 while maintaining their distances apart. To
accommodate the movement of the upstream tube ends, a resilient means is incorporated
in the apparatus to ensure that the tube ends move in a controlled fashion. The resilient
means places tension upon the tubes so as to assist in preventing any lateral movement
of the tubes due to the forces created during twisting. This resilient means comprises
two tension springs 28, both of which are secured at one end to the frame member 24
and at the other end to the plate 20. The two springs 28 are superimposed one upon
another in Figure 1, whereby only one is seen.
[0019] At the downstream end of the tubes, a twisting means is provided for twisting the
two tubes together in alternating directions about the common axis 12. This twisting
means comprises a cylinder 30 formed with two holes within which the downstream ends
of the two tubes are secured. Two annular electric clutches 32 and 34 have their driven
sides secured to the cylinder for driving it, alternately in opposite directions.
Each clutch is drivable by a drive belt 36 continuously driven in opposite directions
by electric motors 38 which form a rotating means for rotating the cylinder 30.
[0020] A direction changing means 40 is provided and this is located at a short distance
downstream from the upstream ends of the tubes as shown by Figure 1, i.e. at a position
in which the tubes rotate less than 360° around the axis 12 for the maximum amount
of turns, i.e. seventy at the downstream ends of the tubes. This direction changing
means is, in fact, located at a position in which each tube turns only 45° in each
direction for the thirty-five rotations at their downstream ends at each side of the
untwisted position shown in Figure 1. The changing means comprises an annular base
plate 42 through which the tubes pass and two magnetic switch means comprising two
U-shaped heads 44 and 46 located at 90° apart around the plate 42 (Figures 1 and 4).
Each head carries 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 of the U. The changing means
also comprises a trigger device for interrupting the magnetic field around each magnet
for the purpose of changing the signal received by the coil in a particular head.
The resultant change in signal causes a disconnection of one of the clutches to the
cylinder 30 and a connection of the other clutch to the cylinder. The trigger device
comprises an interrupter arm 48 which is secured and extends outwardly from a cylinder
50 (Figure 2) which is mounted in bearings 52 in a frame 54. The cylinder 50 is formed
with two axial holes 56 (Figure 4) through which the tubes 10 pass. The arm moves
around the axis 12, from the position in which it lies within a gap in the U of one
of the heads as shown in Figure 2, to a position in which it lies in the gap of the
other head. With the tubes untwisted as in Figure 1, the arm 48 lies midway between
the heads. Upon the arm reaching the position of Figure 2, it interrupts the magnetic
field created by the magnet in head 44 and this changes the signal to the respective
coil whereby the drive through the clutches is changed and the rotational direction
of the tubes is immediately alternated. This change occurs for a 90° operation of
the interrupter arm which corresponds to 70 revolutions at the downstream end of the
tubes between one alternating position and the other.
[0021] A damping device is provided, to prevent the tubes, at the position of interrupter
arm 48, from twisting uncontrollably because of any stored twist throughout the lengths
of the tubes and which may not be dispersed in desired manner upon change in the rotational
direction. This damping device which comprises the cylinder 50, also includes a torsion
spring 58 which closely surrounds the cylinder, on the upstream side of frame 54,
and a cylindrical surround 60. Surround 60 is secured at flange 62 to frame 54. The
spring is securely attached (as by brazing or otherwise bonding) to the cylinder 50
at the downstream end of the spring. The upstream end of the spring is securely attached
to an upper end flange 64 of the surround 60. The twisting of the tubes 10 needs to
overcome torsional resistance of the spring to enable the arm 48 to move from one
head 44, 46 to the other and this creates a damping effect to ensure the arm position
always corresponds to the number of twists in the downstream ends of tubes 10. Two
safety heads 66 are provided upon the base plate 42. These heads 66 are of the same
construction as head 44 or 46 and are disposed spaced around the plate 42, each from
head 44 and 46, i.e. in the 270° arc not normally travelled by the interrupter arm.
In the unlikely event that the arm 48 travels through a head 44 or 46 without the
rotational direction of the tubes being alternated, then the arm will enter the gap
in one of the heads 66 after travelling a short distance further. Interruption of
the magnetic field in either head 66 results in stopping of the electrical motors
38 whereby further twisting of the tubes, which could have resulted in damage to them,
is prevented. Alternatively, a single head 66 (not shown) is provided, equally spaced
from the heads 44 and 46.
[0022] The direction changing means is described more completely in patent application Serial
No. , filed concurrently with this present application in the names of John Nicholas
Garner, Jean Marc Roberge and Norbert Meilenner and entitled "Apparatus For Stranding
Mire".
[0023] In use of the apparatus described in the first embodiment, wire is passed through
each of the tubes 10 from spools 50 mounted in fixed positions relative to the frame
member 24. To cause the wires to become stranded together, the tubes containing the
wires are rotated together at their downstream ends by the twisting means, around
the common axis 12 and also relative to their upstream ends which are prevented from
rotating around this axis. Hence upon the cylinder 30 being rotated for thirty-five
revolutions in the first direction, then the tubes are twisted along their length
for these thirty-five revolutions. The direction changing means 40 then operates as
described in the application in the names of Garner, Roberge and Meilenner as referred
to above, to change the direction of rotation of the cylinder 30. When the cylinder
has completed seventy revolutions in the opposite direction, i.e. thirty-five revolutions
on the other side of the untwisted position shown in Figure 1, then the changing means
operates once more to alternate the direction of rotation again. Thus the two tubes
are twisted together first in one direction and then the other to prevent the wires
from stranding together upstream of the twisting means.
[0024] Upon the wires issuing from the cylinder 30 they may be allowed to strand together
immediately as shown by Figure 1 to form a twisted pair of wires. Alternatively, the
construction described in the first embodiment may form a part of a larger stranding
apparatus for stranding together multiple pairs of wires. In this case a separation
tube means, not shown, may be incorporated downstream of the cylinder 30 to prevent
the wires from stranding together downstream of the twisting means and until they
reach a stranding station at a further downstream position. Such an apparatus for
stranding together multiple wire pairs is described in copending patent application
Serial No. , in the names of John Nicholas Garner, Jean Marc Roberge and Oleg Axiuk,
filed concurrently with this present application and entitled "Forming Cable Core
Units". The apparatus described in this present embodiment is particularly suitable
for apparatus for stranding together multiple wire pairs in that a negligible amount
of lateral movement takes place in the tubes during their twisting and untwisting
operations whereby a plurality of such pairs of tubes may be located side-by-side
in closely spaced positions without danger of the tubes contacting and damaging one
another in use of the multiple apparatus.
[0025] Also during use with the two tubes twisting and untwisting together, the discs 16
hold them in their spaced positions apart at intervales along the tubes and because
of this, the only manner in which the twist and untwist can be accommodated in the
tubes is by lengthening and shortening their apparent lengths axially. This is accomplished
by the movable support plate under the urgency of the springs 28 so that the support
plate is continuously moving in alternate directions along the guides 22 during the
twisting and untwisting movement. The control of the discs and the springs 28 provide
a uniformity of twist along the tubes. As the distance apart of the tubes is maintained
at spaced intervals and the tube twist is controlled, then there is a control on the
degree of drag upon the wires as they pass through the tubes.
[0026] The movable support plate and springs 28 are also of importance for maintaining axial
tension when temperature effects are applied to the tubes, either atmospheric or work
induced. Temperature caused length changes on tubes 70 feet or more in length may
be substantial and without the spring controlled axial tension, tube lateral movement
and drag on the wires would be unpredictable.
[0027] In addition, the use of tubes enables the wires to be threaded with ease through
them before twisting commences. When twisting commences, as the tubes apply pressure
against the side of each wire continuously along the tube length then the pressure
per unit length of tube is low compared to that which results when spaced dividers
and guiding elements are used as with the prior art. Hence, lower forces need to be
overcome to enable movement of the wires through the tubes. Indeed, wire throughput
speeds of 450 feet/minute can be obtained through each tube of this apparatus without
operating at full capacity of the apparatus. With thirty-five turns of the tubes in
each direction from the equilibrium untwisted position, this has provided a 2.9 inch
pitch for the stranded together wires.
[0028] A further advantage which stems from the construction described in the first embodiment
is with regard to the use of the bearings 26. These bearings enable each tube to rotate
about its own axis at the upstream end and this reduces the torsional twist upon each
individual tube because the upstream end of each tube is allowed to freely rotate
under the twisting effect imposed upon the tube. Hence, the use of freely rotatable
upstream ends of the tubes in the way described ensures that the useful life of the
tubes is increased by a reduction in the torsional stresses.
[0029] In a modification of the first embodiment (not shown), the spring 58 has an adjustable
clamp means attachable to any point on the spring. This has the effect of changing
the stiffness in the spring and the number of twists in the tubes before the arm 48
moves from one head 44 or 46 to the other to effect direction change in cylinder 30.
[0030] In a second embodiment (Figure 5), the two tubular construction held by the discs
16 is replaced by two side-by-side tubes 52 which are held together by a surrounding
holding tube 54 which engages the outer peripheral surfaces of the tubes 52 as shown.
The tube 54 is bonded to the tubes 52 at the positions of contact. At its downstream
end the tube 54 is provided with a twisting means as described in the first embodiment.
At the upstream end, the tube 54 is mounted to a tube support plate also as described
above except that the tube is non-rotatably fixed to the support plate whereby the
upstream ends of the tubes 52 are also fixed.
[0031] In use, with the outer tube 54 being rotated by the twisting means, the two tubes
52 are also twisted one about the other about a central axis indicated by arrow 56
in Figure 4 to apply twist to the wires being fed individually down the two tubes
52. The construction of the second embodiment has similar advantages to those described
in the first embodiment.
1. Apparatus for stranding wire characterized in that it comprises:-
a tubular means (10, 52, 54) defining passage means forming
at least two feedpaths for wires along the tubular means with the feedpaths held in
fixed positions apart in at least some locations along the tubular means, the tubular
means being rotatably flexible about a common axis to torsionally twist the tubular
means and thus the passage means around said axis from an untwisted position;
holding means (20, 22) to hold the tubular means against rotation about said axis
at an upstream position of the tubular means;
wire twisting means (30) at a downstream position of the tubular means to torsionally
twist the tubular means, said feedpaths extending through the twisting means;
rotating means (32, 34, 36, 38) for rotating the twisting means together with the
downstream part of the tubular means for a predetermined number of revolutions about
the common axis alternately in one direction and then the other;
direction changing means (40) to change direction of rotation of the twisting means
after the twisting means has rotated the predetermined number of revolutions in each
direction; and
resilient means (28) associated with one of the ends of the tubular means to enable
movement of said one end in the axial direction during twisting and untwisting of
the tubular means.
2. Apparatus for stranding wire characterized in comprising at least two tubes (10,
52, 54), each defining a passage forming a feedpath for a wire along the tube, the
tubes being rotatably flexible about a common axis to torsionally twist the tubes
and thus the passages around said axis from an untwisted position in which the tubes
extend axially and lie substantially parallel, holding means (20, 22) to hold the
tubes against rotation about said axis at an upstream position of the tubes, wire
twisting means (30) at a downstream position of the tubes to torsionally twist the
tubes, said feedpaths extending through the twisting means, rotating means (32, 34,
36, 38) for rotating the twisting means together with the downstream part of the-
tubes for a predetermined number of revolutions about the common axis alternately
in one direction and then the other, direction changing means (40) to change direction
of rotation of the twisting means after the twisting means has rotated the predetermined
number of revolutions in each direction, means (16) to prevent movement towards each
other or apart of the tubes in spaced locations between the ends of the tubes, and
resilient means (28) associated with one of the ends of each tube to enable movement
of said one end in the axial direction during twisting and untwisting of the tubes.
3. Apparatus according to claim 2, characterized in that the means to prevent movement
towards each other or apart of the tubes comprises a plurality of tube holding means
(16) which are spaced apart in the axial direction and hold the tubes in fixed positions
apart.
4. Apparatus according to claim 3, characterized in that the tube holding members
comprise discs (16) having a hole or holes through which the tubes extend.
5. Apparatus according to claim 2, characterized in that the means to prevent movement
towards each other or apart of the passages comprises a holding tube (54) which surrounds
the two tubes (52) and holds them in fixed relative positions.
6. Apparatus according to claim 2, characterized in that the holding means comprises
an end plate (20) mounted upon the upstream ends of the two tubes (10), the end plate
being slidably carried by a fixed frame (24) and the resilient means comprises at
least one spring (28) associated with the end plate to urge it towards the frame and
place the tubes in axial tension.
7. Apparatus according to claim 6, characterized in that the end plate is slidable
upon two guide shafts (22) mounted upon the frame, and two tension springs (28) located
between the frame and the end plate and one at each side of the longitudinal axis
urge the plate along the guide shafts towards the frame.
8. Apparatus according to claim 6, characterized in that the two tubes (10) are individually
rotatably mounted in the end plate.
9. Apparatus according to claim 2, characterized in that the two tubes (10) are individually
rotatably mounted each by one end.
10. Apparatus according to claim 1, characterized in that the tubular means comprises
a single tube formed with two parallel passages forming the passage means.
11. Apparatus according to claim 1; characterized in that the tubular means comprises
a single tube formed with a single passage forming the passage means, the single passage
having two spaced regions to define the feedpaths and a narrower region interconnecting
the spaced region.
12. A method of stranding wires together characterized in that feeding the wires along
individual feedpaths formed by passage means within tubular means, torsionally twisting
the tubular means about a longitudinal axis alternately for a predetermined number
of twists in one direction and then in the other, from an untwisted position, to twist
the individual wires as they are being fed through the passage means alternately in
said directions, said alternate twisting being performed while preventing the feedpaths
from moving laterally towards each other or apart and while a resilient load is applied
upon one end of the tubular means to place it in axial tension, issuing the wires
from the tubular means in an individually twisted condition and enabling the twisted
wires to strand together by virtue of their twist in a position downstream from the
tubular means.