Note: Descriptions are shown in the official language in which they were submitted.
- 1179~
This invention relates to the forming of cable core
units.
It is known that the stranding of wires together to form
a wire unit 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.
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.
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 ~lires"
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
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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 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.
In copending Canadian patent application No. 410,002 in the
names of John Nicholas Garner, Jean Marc Roberge and filed concurrently
with this present application and entitled "Stranding Wires", there is
described a further alternative to the construction covered by U.S.
Patent No, 3,910,022 and 4,325,214. In the application entitled
"Stranding ~lires," 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
-
~174911
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.
While the stranding apparatus as described in each of the
patents referred to above successfully overcome the problems associated
with the use of heavy rotatable machinery, no apparatus has yet been
devised for simultaneously forming a plurality of wire units each
formed in a manner disclosed in the above patents and application, and
then for subsequently combining these wire units in the form of a cable
core unit.
Accordingly, the present invention provides apparatus for
forming a cable core unit from a plurality of wire units, each of at
least two stranded together wires, comprising a plurality of wire guide
means, each for the wires of one of the units, each guide means having
a longitudinal axis extending in a wire pass direction, being
rotationally flexible, and defining individual feedpaths for the two
wires of its unit to maintain the wires separate as they proceed to one
of at least a first and second twisting stations disposed downstream of
the guide means with the second twisting station downstream of the
first station; each guide means terminating at its respective station
in a twisting means which is rotatable at its station around the
feedpaths of the guide means to effect a rotational twist to the guide
means and thus of the feedpaths around the axis, rotating means to
rotate the twisting means in each station and effect rotational
twisting of each guide means and its feedpaths for a plurality of
revolutions about its axis alternately in one direction and then in the
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other to introduce and impose an alternating twist in the wires and
hold the wires separate as they move towards the twisting means; a
stranding station downstream of the twisting stations with at least a
section of the feedpaths for wires for some wire units being curved and
of fixed orientation between each twisting station and the stranding
station to cause convergence of the feedpaths of the wires of each unit
with the wires of other units as they approach the stranding station
and to enable the wire units to combine together to form the cable core
units, and separation tube means to prevent the wires for each wire
unit from stranding together before they reach the stranding station,
said separation tube means being rotatable with the twisting means and
extending in curved configuration along the curved feedpath sections,
with flexibility to enable the tube means to be maintained in its
curved configuration along said fixed path section during rotation of
the tube means in said alternating directions and with torsional
rigidity to avoid build-up and retention of twist.
With the above apparatus and with the guide means
terminating at different twisting stations, it has been found that the
width across the apparatus, i.e. transversely to the feedpaths, is
reduced to a minimum and this is dictated primarily by the permissible
closeness of the guide means. In a preferred arrangement, the guide
means is of the construction described in the patent application
referred to above entitled "Stranding Wires" in the names of John
Nicholas Garner and Jean Marc Roberge. In that construction, a guide
means comprises at least two tubes which define a passage for the wires
for each wire unit. Lateral vibration of the tubes during twisting is
minimal so as not to be a factor in determining the closeness together
~17~911
of the guide means in apparatus according to the present invention.
Twisting means is necessarily of larger dimensions in a lateral
direction to the feedpaths than the guide means. The disposition of
the twisting means in the different twisting stations results in a need
for less width across the apparatus than if the twisting means were all
located at one station. Also, in grouping the twisting means in this
way, it simplifies the driving of all the twisting means at each
station by common driving means and this is an important consideration.
In a practical construction, it is shown that where a cable core unit
is to be made having twenty-five wire units each of a stranded pair of
wires, then if three twisting stations are employed, spaced downstream
of the feedpaths one after another, then the twisting means may be
placed at each of these stations to provide an overall width across the
apparatus, i.e. transversely to the feedpaths, of around 20 inches. In
such an arrangement, the preferred construction has frames for holding
the twisting means in position and the wire guide means extend to the
twisting means along paths which are disposed around a common axis of
the apparatus. Some of the guide means and thus the twisting means are
disposed outwardly of the common axis from others. In a preferred
arrdngement~ the outwardly disposed twisting means are located around
one pitch circle and inwardly disposed twisting means are disposed
around another pitch circle or pitch circles.
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 incross-section, of apparatus for forming insulated conductors into
stranded pairs or wire units and for forming a cable core unit from the
stranded pairs;
1174$1~
Figure 2 is a cross-sectional view taken along line II-II
in Figure 1 showing diagramatically the relative positions of guide
means for the pairs around a common axis of the apparatus, details of
structure of the apparatus being omitted;
Figures 3, 4 and 5 are cross-sectional views taken along
lines III-III, IV-IV, and V-V respectively in Figure 1; and
Figure 6 is a scrap cross-sectional view of the apparatus
taken along line VI-VI in Figure 1 and on a larger scale.
The apparatus shown in the drawings is an apparatus for
the manufacture of a cable core unit from twenty-five wire units, i.e.
stranded pairs of insulated electrical conductors (referred to as
"wires" in this specification). The core unit may be intended to form
a complete cable core, or the core may be made from a plurality of such
units.
The apparatus comprises a plurality of wire guide means
for each wire pair. As is shown by Figure 1, each guide means 10 has a
longitudinal axis which extends in the wire pass direction, i.e. from
the left to the right in Figure 1. The twenty-five guide means 10 are
disposed in substantially parallel relationship and also extend
parallel to a common axis 12 of the appdrdtus. As is clear from
Figures 1 and 2, all the guide means are disposed around the common
axis 12 and are located upon three pitch circles centered upon the axis
12. In Figure 2, the guide means 10 are represented, for simplicity,
as circles. Three inwardly disposed guide means 10 are equally spaced
around an inner pitch circle 14, nine guide means 10 are equally spaced
around intermediate pitch circle 16 and the remaining thirteen guide
means are equally spaced around an outer pitch circle 18.
~1749~i
As shown by Figure 1, each guide means is in the form of
two guide tubes 20 extending one alongside the other, from a tube
support plate 22 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 20, which is, in turn,
spring urged upon parallel guides 24 towards a fixed frame member 26.
The tubes are rotatably flexible for the purpose of withstanding the
rotational forces involved when downstream ends of the tubes are
rotated relative to upstream ends and each at its twisting station,
around another longitudinal axis located substantially symmetrically
between the tubes. This rotation is alternately in one direction and
then in 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 for this rotational flexibility and may
be made, for instance, from stainless steel or from an acetal
homopolymer, e.g. as sold under the Trademark "DELRIN".
The construction and operation of each guide means and its
method of mounting to the frame member 26 are described in copending
Canadian patent application No. 410,002, 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 is
provided for each twisting means (to be described) as shown by Figure
1. This changing means 28 comprises a magnetic switch means which is
triggered by an interrupter arm as described in copending Canadian patent
application Serial No. 409,974, 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
~1~4~1~
described in that specification, each changing means 28 is located a
short distance from its associated plate support 22.
Three twisting stations 30, 32 and 34 are provided in the
apparatus. All of the guide means 10 have twistinq means disposed in
one of the three twisting stations. It is convenient for design
considerations particularly, that all the guide means disposed on a
particular pitch circle 14, 16 or 18 terminate in twisting means
disposed at one only of the stations 30, 32 and 34. In this particular
apparatus, the three guide means 10 on the pitch circle 14 terminate at
a twisting means 36 disposed at twisting station 30. Also, the guide
means 10 disposed upon pitch circles 16 and 18, respectively, terminate
at twisting means 38 and 40 at the twisting stations 32 and 34.
At each twisting station, a frame means is provided for
holding the twisting means. As is clear from Figure 1, each frame
means comprises two frames which are spaced apart along the common axis
12 and each twisting means is carried by both of the frames at its
respective twisting station. While Figure 1 shows only certain of the
guide means and twisting means of the apparatus, the illustrations in
Figures 2 to 5 clearly show the positions of all of the twisting means
and guide means of the apparatus.
The tubes of the guide means on the inner pitch circle 14
extend for approximately 65 feet from their tube support plate 22 to
the twisting station 30. This distance may of course be greater or
smaller, dependent upon design requirements. The other twisting
stations 32 and 34 are disposed slightly downstream along the axis 12
from station 30.
117~91~
Each twisting means 36, 38 and 40 comprises a cylinder 42
formed with two holes (not shown) within which the downstream ends of
its two tubes 20 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 within the frames 48, 50 and 52 at the
stations 30, 32 and 34. The clutches in each group are driven by a
common drive belt 54 or 56 and the drive belts at each twisting station
are driven continuously, each in one direction around pulley wheels 58
and 60 secured to drive shafts 62 (which are in line in Figure 1). The
drive shafts are driven by a single electric motor 64 (Figures 1 and 3).
Each twisting means, therefore, comprises a twisting assembly of the
two clutches and the associated cylinder 42. This assembly is
rotatable within two annular plates 65 which are held to the two frames
48, 5n or 52 by bolts as indicated by positions 70 in Figure fi. The
cylinder 42 of each assembly lies within aligned apertures 66 of its
two frames (see Figure 6), each of the apertures opening into a central
hole 68 formed in the frames, whereby the assembly is removable in its
assembled state by moving it radially from its apertures 66, into the
central hole and then axially away from the frames. Figures 3, 4 and 5
show clearly the relative sizes of the central apertures 68 and of the
positions of the twisting means around the apertures in each case.
Downstream of each twisting means 36, 38, a separation
tube means extends, said means being to prevent the wires of each wire
unit from stranding together until they reach a stranding station (to
be described). Immediately downstream of each twisting means 36, 38,
this separation tube means comprises a single tube 72 which is secured
1174911
at its upstream end to its cylinder 42 and at its downstream end is
rotatably held by a bearing 74, in a frame 76, lying immediately
downstream from the twisting station 34. These tubes 72 are
torsionally rigid, i.e. as they rotate with their twisting means, they
do not torsionally twist as does each guide means. Each tube 72 is
formed from metal or rigid plastic. The tubes 72 pdSS through the
central apertures 68 of frames 50 and 52 as they move towards the frame
76 as shown by Figures 1, 4 and 5. As is also clear from Figures 1, 3
and 4, each guide means 10 terminating at twisting stations 32 and 34,
passes through either a clearance ho1e in each upstream frame 48 or 50
or alternatively, the guide means passes through a bearing 78 in each
frame as shown by these figures.
Each of the guide means and tubes 72 leading to the frame
76, or in the case of the guide means terminating in the twisting means
40, is to be used to enable each of its wires 80 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 40 is at a
diameter only sufficient to allow all guide means and twisting means to
be passed between and held by the various frames while being suitably
20 drivably connected to the motor 64 without any interference between one
tw1sting 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 appartus should provide a cable core unit 82 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
1174911
core unit 82, it is essential that a stranding station 84 is
immediately at a position upstream of a core unit forming station 86.
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.
For the above purpose, separation tube means extend
downstream beyond frame 52 and 76 and have the properties which will
now be discussed to enable them to 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 into a single
path which is coincident with the axis 12 at the station 86.
As shown by Figure 1, each separation tube means
comprises a wire separation tube 88. In the case of each tube 72
terminating at the frame 76, the paths for the wires of each pair to be
stranded are continued by a separation tube 88 which passes through
bearings 90 in a support frame 92 and terminates at a support frame 94
which is disposed immediately upstream of the stranding station 84.
These tubes 88 are secured to the tubes 72 so as to rotate with them.
Wire separation tubes 88 also are secured to and extend from the
cylinders 42 of twisting means 40, and these tuhes 88 pass through
clearance holes (not shown) in the frame 76, which lies close to the
cylinders 42, and then proceed through bearings 90 to terminate at
frame 94. The tubes converge as they pass through frame 92 to frame 94
and each tube is held upon its curved path by the frames.
Clearly, each tube is required to rotate around its axis
which coincides with the fixed curved feedpath section for the wires to
1~749~1
be fed through it. Each tube must have sufficient flexibility to be
maintained in this curved configuration while enduring alternating
compressive and tensile stresses to give a satis,factorily long working
life. Each tube 88 also has torsional rigidity to prevent it from
twisting thereby avoiding build-up and retention of twist. The tubes
88 of this embodirnent are formed from an acetal homopolymer as sold
under the trademark "DELRIN" and have an outside diameter of 0.22" and
an inside diameter of 0.075". These tubes pass through the frame 92 to
frame 94 at pitch circle diameters, which while decreasing, still
maintain the relative positions of the tubes at frame 94, Although the
outermost pitch circle diameter is reduced from around 20" at frames 76
to approximately 8" over a distance of approximately 20" along the axis
12, the tubes 88 satisfactorily withstand the stresses involved.
Another suitable material is stainless steel. The structure of the
tubes 88 and the manner in which they are held to the frames 92 and 94
is described in complete detail in copending Canadian patent application
No. 409,994, in the names of John Nicholas Garner and Jean Marc Roberge,
filed concurrently with this present application and entitled
"Apparatus For Stranding At Least Two Wires Together".
In use of the apparatus as 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 f,rst 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
12
117~911
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. Upon the wires for
each pair passing through its twisting means 36 and 38, the wires
immediately pass from the two tubes 20 into a respective tube 72.
These wires then proceed into their separation tubes 88. In each tube
88 the two wires 80 for each pair are fed one on either side of each of
two pins in the manner described in copending Canadian application No.
409,994 referred to above under the title "Apparatus For Stranding AT
Least Two Wires Together". These pins prevent the wires from stranding
together under the action of the twisting means while in the tubes 88.
The pins also prevent the wires from stranding together during their
movement along the tubes 72 and before reaching the tubes 88. The pins
in tubes 88 leading from the twisting means 40 also prevent stranding
of the wires in these tubes.
The alternately rotating tubes 88 maintain the converging
curved paths of their axes to cause the unstranded wires to issue from
the tubes at stranding station 84 and in closely adjacent positions.
Pairs of wires then strand together from the action of the twisting
means. The stranded wire units then move into a conventional binding
head 96 at station 86 to bring them together as core unit 82. Because
of the closeness of the stations 84 and 86, there is negligible
untwisting of wires of the wire units before the wire units come
together in the station 86. Frictional contact between the pairs and
the use of a binding tape, resists any unwinding tendency. For this
purpose, a conventional spool 98 of tape is provided which wraps tape
100 around the core unit 82 as it emerges from the head.
117491i
The above apparatus shows that twenty-five pairs of
stranded wires (or wire units) may be formed into a cable core unit
after having twist imposed in the wires by the use of alternately
rotating twisting means. The particular size of apparatus constructed
according to the basic concept described in the embodiment depends upon
the numbers of pairs of wires required in the final cable core unit.
As can be seen, the apparatus is compact transversely of the feedpath
for the wires, i.e. transversely to the axis 12. In this particular
case, the diameter of the outermost pitch circle is approximately 20".
This renders the apparatus attractive for commercial application.
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 Canadian patent application Serial No. 409,964, filed
concurrently with this patent application in the names of John Nicholas
Garner, Jean Marc Roberge and Douglas Baxter entitled "Apparatus For
Stranding Wire".
s~ 14
