[0001] This invention relates to apparatus for stranding at least two wires together to
form a wire unit.
[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 or units of wires as
used in telephone systems improves electrical characteristics such as reducing cross-talk.
[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 U.S. 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 its downstream end for twisting it. The elongate 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] In another patent application Serial No. in the names of John Nicholas Garner and
Jean Marc Roberge filed concurrently with this present application and entitled "Stranding
Wires", there is described a further alternative to the constructions covered by U.S.
Patent No. 3,910,022 and 4,325,214. In the application entitled "Stranding Wires",
apparatus for stranding wires comprises at least two tubes each defining a passage
for wire, the tubes being rotatably flexible about a common axis to torsionally twist
the tubes together around the axis to enable each of the wires to be given a twist
by the twisting means while the tubes prevent the wires from twisting together. The
tubes are prevented from moving towards or away from each other during the twisting
operation and a resilient means is used at one end of the tubes to place the tubes
continuously in tension and to allow for end movement of the tubes as the tubes change
in effective length during each twisting and untwisting operation. The wires strand
together to form a wire unit immediately they pass downstream from the twisting means.
[0007] A problem arises where it is found to be necessary to strand wires together at a
position not only downstream from the twisting means but also out of alignment with
the twisting means. In this case, it is necessary for each of the wires to be moved
at an angle from the twisting means to the downstream stranding station. There may
be such a requirement for change in direction of the wires in apparatus in which a
plurality of the elongate or tubular members are to be used in an apparatus for imposing
twist into wires to be formed into a plurality of stranded pairs during the manufacture
of a cable core unit. In such an arrangement, it can be seen that it would be necessary
to cause the wires to converge downstream of the twisting means so that immediately
after the stranding of the wires into pairs, the stranded wire pairs are together
to form the core unit.
[0008] The present invention concerns an apparatus and a method of stranding wires which
overcomes the above problem.
[0009] Accordingly, the present invention provides apparatus for stranding at least two
wires together comprising:-
wire guide means extending downstream in a wire pass direction to a twisting station
to define individual feed paths for wires and prevent the wires from twisting together
as they move along the guide means to the twisting station, a twisting means in the
twisting station and connected to the wire guide means, the twisting means having
means to rotate it alternately, in one direction and then the other, for a plurality
of revolutions to rotate the wire guide means at the twisting station and place a
rotational twist in the guide means alternately in one direction and then the other
about a longitudinal axis of the guide means, a stranding station downstream along
the feedpaths from the twisting station with at least a section of the feedpaths the
wires being curved and of fixed orientation between the twisting and the stranding
stations, and means extending between the twisting and stranding stations to prevent
the wires, after passage through the twisting means, from stranding together before
they reach the stranding station, said stranding prevention means comprising a wire
separation tube which is curved to extend along the fixed curved section of path and
defines the individual feed paths for the wires, said separation tube being rotatable
around an axis of rotation which coincides with the fixed curved path section, and
with a rotational speed equal to that and in the same direction as the twisting means,
and the tube having flexibility to enable the tube to be maintained in its curved
configuration along said fixed curved path section and torsional rigidity to avoid
build-up and retention of twist.
[0010] In use of the above apparatus, because the separation tube is maintained in its curved
configuration, then the wires passing through the tube are maintained separate from
each other whereby stranding does not take place along the curved section of the feedpaths.
Hence, the wires are prevented from stranding together between the twisting station
and the stranding station.
[0011] To maintain the separation tube in its fixed position along the curved section of
feedpaths, it is desirable to mount the separation tube in a bearing in a support
frame through which the tube passes. The frame may lie at any angle to the direction
of the tube at the position at which the tube passes through the frame.
[0012] The separation tube may be formed with two separate passages along its length. However,
it may be difficult to rotate the tube about its own axis while maintaining it fixed
along the curved section of path if it has a cross-section which has two passages,
because of the stiffness of the material. It is desirable, therefore, that the separation
tube has a single passage and feedpath separation means spaced apart along it to separate
the passage into the feedpaths at the location of said separation means only. Hence,
the separation tube is a simple tube construction. It is found that with separation
means spaced apart along the tube in this manner, they suffice to maintain the wires
separate from each other, i.e. they prevent stranding of the wires from one end of
the tube to the other. In a preferred arrangement, the feedpath separation means are
disposed solely at each end portion of the tube. Hence it is a simple matter to locate
the separation means within the end portions.
[0013] The above apparatus is particularly useful when combined with a plurality of other
similar apparatus to form other apparatus for stranding together a plurality of units
of wires, each unit comprising at least two wires twisted together. In this other
apparatus, a plurality of twisting means for the different units are spaced apart.
Wire separation tubes for the different units curve along their own fixed curved sections
of paths and converge to have downstream ends adjacent to one another to present all
of the twisted wires in adjacent positions at the stranding station to enable the
wire units to be stranded together to form a core unit. Such combined apparatus is
described in 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".
[0014] One embodiment 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 in cross-section of apparatus for forming
insulated conductors into stranded pairs and for forming a cable core unit from the
stranded pairs;
Figure 2 is a cross-sectional view through part of the apparatus of Figure 1 and shown
in larger scale;
Figure 3 is a view similar to Figure 2 of another part of the apparatus;
Figure 4 is a diagrammatic end view of a wire separation tube used in the apparatus.
[0015] The apparatus shown in the drawings is an apparatus for the manufacture of a cable
core unit from 25 pairs of insulated electrical conductors (or wires as referred to
in this description). The wires in each pair are stranded together before pairs are
themselves combined and bound with binding tape to form the core unit. The core unit
may be intended to form a complete cable core, or a core may be made from a plurality
of such units.
[0016] This apparatus is constructed in the manner 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".
[0017] As described in the aforementioned application, the apparatus comprises a plurality
of wire guide means, one for each pair of conductors. Each guide means is in the form
of two guide tubes 10, extending one alongside the other, from a tube support plate
12 at their upstream ends to a twisting station at their downstream ends. Each tube
is individually rotatably mounted about its own axis by its upstream end within the
plate support which is, in turn, spring urged upon parallel guides 14 towards a fixed
frame member 16. As will be described, the tubes are rotationally flexible for the
purpose of withstanding rotational forces involved when downstream ends of the tubes
are rotated relative to upstream ends and each at its twisting station, around a longitudinal
axis located substantially symmetrically between the tubes. This rotation is alternately
in one direction and then the other from an equilibrium position in which the tubes
are untwisted and lie parallel as shown in Figure 1. The tubes are formed from a material
which provides this rotational flexibility and may be made, for instance, from stainless
steel or an acetal homopolymer, as sold under the trademark "DELRIN".
[0018] The construction of each guide means, and its method of mounting to the frame member
16 are described in detail in Patent application Serial No. , filed concurrently with
this present application in the names of John Nicholas Garner and Jean Marc Roberge
and entitled "Stranding Wires". A direction changing means 18 is provided for each
twisting means (to be described) guide means as shown by Figure 1. This changing means
comprises a magnetic switch means which is triggered by an interrupter arm as described
in copending 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 Wire". As also described in that specification,
each changing means 18 is located a short distance from its associated plate support
12.
[0019] As described in patent application Serial No. , filed concurrently with this present
application and entitled "Forming Cable Core Units" referred to above, the twenty-five
guide means thus included in the apparatus are arranged in specific manner and there
are three twisting stations for three groups of the guide means. In fact, all of the
guide means are located by the frame member 16 and other frame members around three
pitch circles which are concentric around a common axis 20 as shown by Figure 1. As
described in the application "Forming Cable Core Units", three guide means are located
upon an innermost pitch circle by the positions of their plate supports 12 which are
equally spaced around the common axis 20. The tubes of these three guide means extend
for approximately 65 feet to the first twisting station 22 at which a twisting means
24 for each of the three guide means is held by a pair of spaced parallel frame members
26, the twisting means being in corresponding positions to the associated plate supports
14 whereby the guide means extend substantially parallel with the axis 20. One of
the three innermost guide means is superposed by another guide means in Figure 1 so
that only two, together with their twisting means, are shown.
[0020] Around an intermediate pitch circle, nine guide means are disposed, in the same manner
discussed in the last paragraph, these nine guide means being equally spaced apart
around the axis 20 and terminating, each at a twisting means 28, in a twisting station
30 at a pair of spaced parallel frame members 32. The remaining thirteen guide means
are disposed around an outermost pitch circle and these guide means terminate at a
twisting station 34, in twisting means 36, held between spaced parallel frame members
38. Only two of the guide means and their respective twisting means are shown, for
reasons of clarity, at each of the stations 30 and 34. Each guide means terminating
at twisting stations 30 and 34, passes through either a clearance hole in each upstream
frame 26 or in each frame 26 and 32, or alternatively, the guide means passes through
a bearing 40 in each frame as shown by Figure 1.
[0021] Each twisting means 24, 28, and 36 comprises a cylinder 42 formed with two holes
(not shown) within which the downstream ends of the two tubes are secured. Two annular
electric clutches 44 and 46 have their driven sides secured to the cylinder 42 for
driving it alternately in opposite directions. All clutches 44 and 46 are radially
aligned into two groups between the frames of each pair 26, 32 and 38 and the clutches
in each group are driven by a common drive belt 48 or 50. The drive belts 48 and 50
at each twisting station are driven continuously, each in one direction, around pulley
wheels 52, 54 secured to two drive shafts 56 (which are in line in Figure 1). The
drive shafts are driven by a single electric motor 58.
[0022] Downstream of each twisting means 24, 28, a single tube 60 extends, the tube being
secured to its cylinder 42 and extending to a downstream end held by a bearing 62
in a frame 64 lying immediately downstream from the twisting station 34. These tubes
60 are torsionally rigid, i.e. as they rotate with their twisting means, they do not
torsionally twist as does each guide means. Each tube 60 is formed from metal or rigid
plastic. The tubes 60 pass through central apertures 66 of frames 32 and 38 through
which they pass towards frame 64.
[0023] Each of the guide means and tubes 60 leading to the frame 64, or in the case of the
guide means terminating in the twisting means 36, is to be used to enable each of
its wires 68 to be given a degree of twist by the twisting means while the tubes prevent
the wires from twisting together. The pitch circle for the twisting means 36 is at
a diameter only sufficient to allow all of the guide means and twisting means to be
passed between and held by the various frames while being suitably drivably connected
to the motor 58 without any interference between one twisting means and its guide
means and another. Nevertheless, for stranding together twenty-five pairs of wires,
the diameter of the outermost pitch circle is approximately 20 inches. However, it
is required that the apparatus should provide a cable core unit 72 from these wires.
This involves the bringing together of all of the stranded wire units. To prevent
the stranded wire units time to develop a significant unstranding action before being
formed into the core unit 72, it is essential that a stranding station 74 is immediately
at a position upstream of a core unit forming station 76. Hence, some means is required
to more closely group the unstranded wires together at the stranding station where
stranding into the wire units is then accomplished.
[0024] According to this invention, for this purpose, and as shown by this embodiment, the
apparatus comprises strand prevention means which follow and maintain converging curved
paths although they are caused to rotate in alternating directions together with the
twisting means. These curved paths direct the twenty-five parallel paths for the wires
of the pairs onto a single path which is coincident with the axis 20 at the station
76.
[0025] As shown by Figure 1, each strand prevention means comprises a wire separation tube
78. In the case of the each tube 60 terminating at frame 64, the paths for the wires
of each pair to be stranded are continued by a separation tube 78 which passes through
bearings 80 in a support frame 82 and terminates at a support frame 84 which is disposed
immediately upstream of the stranding station 74. These tubes 78 are secured to the
tubes 60 so as to rotate with them. Wire separation tubes 78 are also secured to and
extend from the cylinders 42 of twisting means 36, and these tubes 78 pass through
clearance holes (not shown) in the frame 64, which lies close to the cylinders 42,
and then proceed through bearings 80 to terminate at frame 84. The tubes converge
as they pass through frame 82 to frame 84 and each tube is held upon its curved path
by the frames.
[0026] Clearly, each tube is required to rotate around its axis which coincides with its
fixed curved path section and must have sufficient flexibility to be maintained in
this curved configuration while enduring alternating compressive and tensile stresses
to give a satisfactory working life. Each tube 78 also has torsional rigidity to prevent
it from twisting thereby avoiding build-up and retention of twist. The tubes 78 of
this embodiment are formed from an acetal homopolymer, as sold under the trademark
"DELRIN", and have an outside diameter of 0.22 inches and an inside diameter of 0.075
inches. These tubes pass through the frame 82 to frame 84 at pitch circle diameters
which, while decreasing, still maintain the relative positions of the tubes at frame
84. Although the outermost pitch circle diameter is reduced from around 20 inches
at frame 64 to approximately 8 inches over a distance of approximately 20 inches along
the axis 20, these tubes satisfactorily withstand the stresses involved. Another suitable
material is stainless steel.
[0027] As shown by Figure 2, the frame 82 necessarily lies at an angle to the direction
of each tube 78 passing through it. This angle depends upon which pitch circle the
tube is disposed. To avoid the need to provide holes in the frame 82 drilled at the
different angles required, each hole 86 is formed normal to the frame and an adjustable
fitting 88 is located within the hole to provide the desired angle. All the fittings
88 are of similar construction and comprise a substantially cylindrical member 90
having a smooth surface portion 92 for sliding reception within its frame hole 86.
One end of the portion 92 terminates in a larger diameter shoulder 94 to engage one
side of the frame. The other end of portion 92 extends as a screw thread 96 to accommodate
a holding nut 98 to assemble it to the frame. The member 90 has a stepped bore 100
which, as shown, is inclined to the axis of the member and this angle is dependent
upon whichever pitch circle position the fitting is used. A bearing 102 held against
a shoulder within the bore by a resilient clip 104, grips a steel sleeve 106 which
is glued to or is a press fit with the surface of the tube 78 passing through the
bearing. As may be seen, the fitting 88 is rotatable in each case, within the frame
82 to adjust the inclination of the bore 100 to the desired smoothly curved path of
its tube 78, the fitting then being secured in position.
[0028] As shown by Figure 3, the downstream end of each tube 78 is secured by a locking
screw 108 within an end 110 of a cylindrical fitting 112. This fitting has a reduced
diameter portion 114 having a passage sufficient for two wires 68 issuing from the
end of tube 78. This portion 114 is rotatably received within a short metal cylinder
116 extending through a hole 118 formed in frame 84 at the required angle.
[0029] Each of the separation tubes 78 has two feedpath separation means spaced apart along
it to separate the feedpaths for the two wires which are to pass through it. Each
of the separation means comprises a pin 120, as shown in Figure 4, which is a diagrammatic
view of the whole length of one of the tubes and indicates the positions of the two
pins which are disposed at its ends.
[0030] .In use of the apparatus described above, each of the twisting means is rotated continuously
in alternating directions for a preset number of revolutions (e.g. 35 revolutions
to each side of an untwisted position of the guide tubes as shown by Figure 1). The
downstream end of the associated guide tubes 20 rotate with the twisting means to
place torsional twist on the tubes first in one direction and then the other about
a longitudinal axis. The alternate rotation of the twisting means is effected by the
direction changing means 28 which alternately operates the clutches 44 and 46. The
wires 80 are passed through the tubes 20 which prevent the wires from twisting together
as the wires move towards the twisting means. The wires pass through the twisting
means 36, 38 or 40.
[0031] Upon the wires for each pair passing through its twisting means 24 and 28, the wires
immediately pass from the two tubes 10 into a respective tube 60. These wires then
proceed into their separation tubes 78. In each tube 78, the two wires 68 for each
pair are fed one either side of each of the pins 120 which thus prevent the wires
from stranding together under the action of the twisting means while in the tube 78.
The pins 120 also prevent the wires from stranding together during their movement
along the tubes 60. The pins 120 in tubes 78 leading from the twisting means 36, also
prevent stranding of the wires in these tubes. Further, the tubes 78 rotate around
the curved paths of their axes while leading the wires along converging paths whereby
when the wires issue from the tubes 78, the wires immediately strand together to form
the pairs, the pairs then being adjacent one another and moving Into the cable core
unit forming station 76. This station is sufficiently close to the stranding station
74 to preclude any substantial untwisting of the wires of each pair before the pairs
come together as the core unit whereupon any unwinding action is resisted by virtue
of their frictional contact.
[0032] The core unit forming station does, in practice, include a device for holding the
wire pairs in the form of the core unit. For this purpose, a conventional binding
head 122 may be used - having a spool 124 of tape which wraps tape 126 around the
core unit as it emerges from the head.
[0033] The above apparatus and according to the invention thus enables a core unit to be
formed from pairs of wires which have been stranded together with a rotatable twisting
means and a torsionally twistable wire guide means with negligible unwinding of the
wires in each pair. Because of the physical need to twist the wires of all the pairs
in spaced positions, the twisting means are also necessarily spaced and if stranding
of the pairs were allowed to take place immediately upon exiting from the twisting
means, then uncontrollable unwinding would occur before convergence of the stranded
pairs at the core unit forming station. By the use of the flexible but torsionally
rigid wire separation tubes according to the invention, this problem is overcome by
delaying of the stranding of wires into their pairs until they lie closely adjacent
to one another and are positioned for movement directly into the core unit forming
station.
[0034] In a modification of the above embodiment (not shown), each guide means in the form
of two tubes 10 is replaced by a guide means comprising a single tube defining a single
axial passage which provides at least two side-by-side feedpaths for wire. The passage
is shaped to prevent wires from moving across the passage to interchange positions
by having a narrow passage region in between wider regions which provide the feed
paths. Such guide means is disclosed in copending patent application Serial No. ,
filed concurrently with this patent application in the names of John Nicholas Garner,
Jean Marc Roberge and Douglas Baxter and entitled "Apparatus For Stranding Wire".
1. Apparatus for stranding a unit of at least two wires together comprising wire guide
means (10) extending in a wire pass direction, downstream to a twisting station (22,
30, 34) to define individual feed paths for wires and prevent the wires from twisting
together as they move along the guide means to the twisting station, the guide means
being rotatably flexible about a longitudinal axis to provide torsional twist in the
guide means and a twisting means (24, 28 and 36) in the twisting station and connected
to the wire guide means, characterized in that the twisting means has means (44, 46,
48, 50, 52, 54, 56, 58) to rotate it alternately, in one direction and then the other
and for a plurality of revolutions, to rotate the guide means at the twisting station
and place torsional twist in the guide means alternately in one direction and then
the other about said longitudinal axis; the apparatus also having a stranding means
in a stranding station (74) downstream along the feedpaths from the twisting station
with at least a section of the feedpaths for wires being curved and of fixed orientation
between the twisting and stranding stations; and means (60, 78) extending between
the twisting and stranding stations to prevent the wires, after passage through the
twisting means, from stranding together before they reach the stranding station, said
strand prevention means comprising a wire separation tube (78) which is curved to
extend along the fixed curved section of path and defines the individual feed paths
for the wires, said separation tube being rotatable around an axis of rotation which
coincides with the fixed curved path section and with a speed and direction of rotation
the same as the twisting means, and the tube having flexibility to enable the tube
to be maintained in its curved configuration along said fixed curved path section
and torsional rigidity to avoid build-up and retention of twist.
2. Apparatus according to claim 1, characterized in having at least one wire separation
tube support frame (82, 84) and wherein the wire separation tube passes through and
is mounted by a bearing (102, 114, 116) within the frame to ensure that the tube follows
the curved section of path with fixed orientation.
3. Apparatus according to claim 2, characterized in that the frame lies at an angle
to the direction of the tube at the position at which the tube passes through the
frame and the bearing is inclined to the angle of the frame.
4. Apparatus according to either of claims 1 and 2, characterized in that the separation
tube has feedpath separation means (120) spaced apart along the tube to separate the
feedpaths at the locations of said means.
5. Apparatus according to either claims 1 and 2, characterized in that the separation
tube has two feedpath separation means (120) disposed one within each end portion
of the tube.
6. Apparatus for stranding together a plurality of units of wires, each unit comprising
at least two wires twisted together, characterized in comprising a plurality of apparatus
according to claim 1, with the twisting means for the different units being spaced
apart, the wire separation tubes each curving along its own fixed curved section of
path with the paths converging towards each other and having downstream ends adjacent
to one another to locate all of the twisted wires in adjacent positions as the units
are formed at the stranding station to enable the wire units to be stranded together;
and a core unit forming station (76) immediately downstream of the stranding station
to combine the wire units into a core unit.
7. Apparatus according to claim 6, characterized in that the twisting means are positioned
around a main axis and the stranding means is located upon said main axis.
8. Apparatus according to claim 6, characterized in having at least one separation
tube support frame (82, 84) disposed between the twisting and the stranding stations
and the wire separation tubes pass through and are mounted individually within the
frame in bearings (102, 114, 116) to ensure that the tubes follow the curved section
of path with fixed orientation.
9. Apparatus according to claim 6, characterized in having at least one separation
tube support frame (82, 84) disposed between the twisting and stranding stations in
a position substantially normal to said main axis and the wire separation tubes pass
through and are mounted individually within the frame in bearings (102, 114, 116)
to ensure that the tubes follows the curved section of path with fixed orientation.