Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR TWISTING
TOGETHER LEN&THS OF FILAMENTARY MATERIAL
This invention relates to methods and apparatus for
twisting together lengths of filamentary material.
Problems are associated with the twisting together
of lengths of filamentary material in different usages. Many
of these problems are associated with the degree of tension
and methods of applying tension to the lengths of filamentary
material as they are pulled along paths during a twisting
procedure. Such problems appertain in particular in the
manufacture of telecommunications cable, i.e. in the twisting
together of two or more lengths of filamentary material in
the form of individually insulated conductors.
In a conventional method of twisting two lengths of
individually insulated conductor into a twisted pair for use
in the telecommunications industry, each individually
insulated conductor is drawn from its own individual supply
reel, the two reels being mounted upon a supply carriage. A
take-up reel provides the pulling tension and each of the
supply reels is provided with a brake mechanism to ensure
that the conductors are not drawn too rapidly from the reels
whereby control is maintained over the twisting process. The
brake mechanisms are operated by a tension arm provided for
each reel. Each insulated conductor is passed tangentially
from its supply reel and around a tensioning pulley mounted
on a pivoted tension arm. Should a conductor issue from a
supply reel too quickly, then the tension arm is allowed to
pivot under a spring force so as to apply the brake mechanism
to the supply reel whereby resistance is increased to
rotation of the reel, thereby restraining unreeling of the
conductor. The resistance offered by the brake is immediate
and this applies a sudden increase in tension to the con-
ductor.
These brake applications are spasmodic and sudden
changing tensions in the conductor limit the speed of
operation of the twisting machine and also place a limit on
the smallest diameter wire which can be twisted in this type
of operation. It has been calculated that the tension
3 30~
applied to the conductor when the brake is applied may be
caused by a tensile load of about 6 lbs. Also, without
operations of the brake, tension is applied because the pull
of the conductor is required to produce reel rotation. As a
result, it is considered that this type of twisting apparatus
may not be safely used on a commercial basis for copper
conductors below 26 AWG, if breakages are to be avoided at a
running speed not in excess of 1200 rpm. Thus the speed of
operation and the minimum size of the conductor to be twisted
is dependent upon the wire strength and therefore upon the
machine capability.
In addition, with the above type of conventional
apparatus, a flyer is used to produce a double twisting
operation. This flyer is rotatably mounted about an axis
passing through the supply carriage so that the flyer rotates
to sweep a volumetric space which includes both the supply
carriage and the two supply reels. Because of the size of
the various components including the supply reels, the sweep
diameter of the flyer during rotation is of the order of
about 3 ft for normal size reels and would be larger for
larger reels.
In an alternative method which has been proposed
for twisting wires together, British Patent Specification
1303106 discloses the positioning of three bobbins in axial
alignment, each bobbin being wound with wire. The wires are
fed from the bobbins through a collecting die and thence to a
flybar which rotates around the bobbins. Because of the
geometry of the apparatus, the flybar extends a substantial
distance beyond the bobbins themselves. Part of the problem
would appear to be that the wires after leaving the bobbins
and approaching the die, balloon outwardly as they are
rotated at high speed by their removal from the bobbins.
In a further disclosure, namely U.S. Patent
3,715,877, granted February 13, 1973, two stationary bobbins
are mounted in apparatus and wires are drawn axially over the
ends of the bobbins to twist them together. The drawing off
of the wires for the bobbins is controlled by a flybar which
rotates around the end of each bobbin and is frictionally
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held in position at its pivotal center so as to resist
rotation and induce tension in the wire. With this ap-
paratus, undoubtedly, tension is applied in each wire as it
is being drawn off the bobbin by the need for the wire to
rotationally drive its flybar. This apparatus is thus
extremely restrictive upon the minimum diameter of wire which
can be twisted and/or upon the running speed of the ap-
paratus. Further to this, the latter document discloses
complex machinery for the simple purpose of twisting wires
together.
The present invention provides a method and
apparatus for twisting together at least two lengths of
filamentary material with a double twist and which also seeks
to lessen or avoid the above disadvantages.
Accordingly, the present invention provides a
method of twisting together at least two lengths of filamen-
tary material with a double twist comprising~ causing the
lengths of material to follow paths from reels of material
located in axial alignment within a surrounding concentric
cylindrical means, the paths extending in one axial direction
from the reel surfaces and between the surrounding
cylindrical means and ends of the reels to a first twist
position axially beyond the reels and substantially on the
common axis of cylindrical means and reels, radially outwards
from the cylindrical means to extend in the other axial
direction through guide means radially outside the
cylindrical means, and then axially away from the cylindrical
means substantially on the axis thereof to a second twist
position; and drawing the lengths of material along their
paths while rotating the guide means around said axis, the
lengths of material being unwound from the reels and forced,
by the speed of rotation, against the inner surface of the
cylindrical means, and sliding against said inner surface as
they pass towards said first twist position.
According to the invention also there is provided
apparatus for twisting together at least two lengths of
filamentary material with a double twist comprising: a
cylindrical means with a smooth inner surface; mounting means
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within and at a first end of the cylindrical means for at
least two axially aligned reels of filamentary material with
the reels substantially concentric with the cylindrical
means; a die concentrically disposed at the second end of the
cylindrical means for causing convergence of~the lengths and
for leading them to a first twist position; ~ ~ means for the
lengths of filamentary material, the fly means located
radially outside the cylindrical means for directing the
lengths axially from the second end towards th~eLfirst end of
the cylindrical means; means for rotating the ~ means
concentrically around the axis of the cylindrical means; and
a second twist position axially beyond the first end of the
cylindrical means.
Preferably, in the apparatus of the invention, the
~ means i5 located axially along the outside surface of the
cylindrical means and the rotating means rotates the
cylindrical means around its axis and around the mounting
means.
In the use of the method and the apparatus accord-
ing to the invention, the reels are not rotated by the
lengths of filamentary material being drawn off them. In
addition, the apparatus does not employ braking mechanisms
for the reels nor does it employ conventional flybars for
controlling the unwinding of the filamentary material. Thus,
these particular items of conventional apparatus which add to
the tension in the material are avoided. In the case of the
method and the apparatus of the invention, resistance to
movement of each length of filamentary material along its
path and which causes tension in the material, need only be
offered by frictional contact of the materhal with the
surfaces of the cylindrical means and the f ~ means. The
frictional coefficient may be reduced to a minimum by
providing smooth finishes to inner and possibly outer
surfaces of the cylindrical means and advantageously to the
contacting surfaces of the guide means. Thus, substantially
uniform and minimal tension results and this tension varies
in a negligible fashion for any increase in pulling load upon
the material such as to increase its throughput speed. In
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addition, the lengths of material are not subjected to sudden
tension increases such as are found when relying upon the
pull of the filamentary material to rotate the reels to
enable the unwinding process as in conventional apparatus.
As a result, because of the lessening of tension,
and the avoidance of sudden increases in tension, such as for
instance as provided by braking of reels, then the method and
the apparatus of the invention may be used for double
twisting together lengths of filamentary material of much
smaller diameters than has heretofore been possible. In
particular, with regard to the telecommunications industry,
it has been found that the process and apparatus of the
invention may provide a double twist to insulated copper
wires with diameters as small as 36 AWG without resultant
breakage. Also, because of the extremely small tensions
involved, speeds of at least 2400 rpm of the flyer (i.e. 4800
twists per minute) are possible without breakage problems.
The actual twist lay (i.e. the pitch) depends upon the
throughput speed of the material, assuming that the flyer
speed stays constant.
With the use and the method of the invention, the
inner surface of the cylindrical means restricts the balloon-
ing out of the filamentary material as it is being unwound
from the reels. Thus, if the diameter of the cylindrical
means is merely sufficient to allow the material to pass
comfortably between the reel ends and the inner surface of
the cylindrical means, then the radial dimensions of the
apparatus are minimized. With regard to this, with use of
conventional apparatus in the telecommunications industry for
double twisting individually insulated conductor wires, the
flyer bar has a diameter around 36 inches when using what are
referred to as "half telephone reels". In the apparatus of
the present invention, the flyer, when attached to the
outside of the cylindrical means, need only have a diameter
of approximately 24 inches when using larger reels known as
"Hearl Heaton" reels. This smaller sweep diameter is
sufficient for the cylindrical means to be positioned around
Hearl Heaton reels which carry approximately up to four times
~3~S908
the length of conductor wire that may possibly be carried by
half telephone reels used in the conventional equipment.
In the apparatus of the invention, reels within the
cylindrical means may be either stationary or rotatably
driven, driving of the reels affecting the twist lay. If the
reels are driven, they should be driven at rotational speeds
less than that of the guide means. Driving of the reels does
not assist in drawing off the filamentary material which, as
has been stated, is merely unwound from each reel as it is
pulled axially over the reel end.
One embodiment of the invention will now be
described by way of example, with reference to the accompany-
ing drawings, in which:
Figure 1 is an isometric view of apparatus for
providing a double twist to individually insulated conductors
for a telecommunications cable, the apparatus being in closed
condition;
Figure 2 is a cross-sectional view, to a larger
scale, through the apparatus taken along line II-II in Figure
1 and showing rotational parts of the apparatus in one
angular position;
Figure 3 is a view similar to Figure 2 showing the
rotational parts in another position and with reels of
insulated conductor mounted in the apparatus;
Figure 4 is a view similar to Figure 1 showing the
apparatus in an open condition;
Figure 5 is a cross-sectional view along line V-V
in Figure 4;
Figure 6 is an isometric view of part of the
apparatus taken in the direction of arrow V in Figure 3; and
Figures 7 and 8 are diagrammatic plan views,
respectively, of the positions of parts of the apparatus as
shown in Figures l and 4.
As shown in Figure 1, apparatus for providing a
double twist to two lengths of individually insulated
conductor generally comprises a cylindrical means which is a
cylinder 12 rotatably mounted in a frame 14.
130S91~8
As shown more particularly in Figure 2, the
cylinder 12 comprises a truly cylindrical section 16 and two
domed end sections, an upper domed end section 18 and a lower
domed end section 20. The lower domed end section is secured
to a downwardly extending drive shaft 22 which is mounted in
bearings 24 within a cylindrical mounting 26 which is, in
turn, secured to and extends upwardly from a lower plate 28
of the frame structure 14.
The cylindrical section 16 is secured to the lower
domed end section 20 and the upper domed end section 18 is
pivotally connected to the cylindrical section 16 at a
pivotal position outwardly from the cylinder 12. As shown in
Figure 3, this pivotal position is provided by a hinge member
30. The hinge member 30 comprises part of a flyer means
which also includes at least one ring 32 which is axially
spaced from and is in axial alignment with the hinge member
30. As can be seen from Figure 3, the ring 32 is secured to
the cylindrical section 16.
Means is provided for rotating the flyer means
around the axis of the cylinder 12. As can be seen from
Figures 2 and 3 this rotating means comprises an electric
motor 34 attached to the underside of the lower frame plate
28, the electric motor being drivably connected to the
driving shaft 22 by means of a drive pulley belt 36.
In use of the apparatus as will be described,
individually insulated conductors being passed through the
apparatus will move in sliding engagement with the surfaces
of the cylinder. So as to reduce frictional resistance to
this movement to a minimum, all surfaces with which the
conductors may engage are made as smooth and as friction
resistant as possible. In addition, so as to reduce the
moment of inertia of the rotating mass of the cylinder 12
when in use, it is convenient to use lightweight and strong
materials. While metal may be used, the cylinder may be
formed from a fiberglass polyester structure. The friction
resistant surface upon the inside of the cylindrical section
16 and particularly around the outside of the domed end
sections may be provided by an alloy of cobalt and nickel
591:~8
which provides high resistance to wear and low friction
characteristics. Such a material is known under the trade
~e of Triballoy.
~a~ As shown in Figures 2 and 3, a die 38 is provided
concentrically within the domed end section 18, the die
provided for convergence of the lengths of insulated con-
ductor as they pass out of the cylinder. At the other end of
the cylinder, an inclined guide passage 40 is formed axially
along the drive shaft 22 to guide the lengths of filamentary
material from the flyer, the guide passage 40 terminating in
an extension passage 42 which is coaxial with the axis of
rotation of the cylinder 16. The extension passage 42 guides
the filaments to a pulley 44 around which they pass at a
second twist position before continuing away from the
apparatus to a take-up reel (not shown).
The apparatus further comprises a mounting means
for mounting two axially aligned reels of individually
insulated copper conductor within the cylinder. The mounting
means comprises a support shaft 46 which is held within the
upper end of the drive shaft 22 within bearings 48. A
suitable gear train 50 drivably connects the support shaft 46
with the drive shaft 22 for the purpose of ensuring that the
support shaft 46 is held stationary relative to the frame 14
when the drive shaft 22 i6 rotated by the pulley belt 36.
This type of gearing arrangement is well known in engineering
fields, particularly in twisting machines for the tele-
communications industry. Hence, no further description of
this gearing arrangement is necessary.
As can be seen from Figure 3, the die 38 is held
within an axially extending collar 51 of the domed upper end
section 18. The collar is provided with an outlet orifice 52
for passage of the conductors from the die to the hinge
member 30 of the flyer means. The die 38 has an upwards
extension 54 which is supported by bearings 56 within a
surrounding cylindrical mount 58. The mount 58 is in turn
secured to a radially extending planar flange 60 which is
itself carried upon an upper plate 62 of the framework 30.
The edges of the plate 62 are supported by linear bearings
i3~59~8
upon two parallel shafts 64 carried upon the frame 30 so as
to allow the plate 62 to be moved horizontally. This
movement is easily controlled manually. Extension 54 to the
die 38 is provided with an axially extending passage 68 to
assist in threading the insulated conductors through the die
and out of the orifice 52 as will be described.
Two reels 70 and 72 which are to be mounted inside
the cylinder 12 upon the support shaft 46 are reels commonly
referred to as "Hearl Heaton" reels. These reels are capable
of carrying a quantity of individually insulated conductor
which is four times that which may be carried by half
telephone reels normally mounted within a conventional double
twisting machine as used in the telecommunications industry.
Even though the Hearl Heaton reels are capable of carrying
such a quantity of conductor, they are of such a diameter
across their ends 74 that the cylinder 12 which is made
sufficiently small in diameter to enable the conductor to
pass comfortably between the ends 74 and the cylinder, locate
the flyer means 30 and 32 at a small diameter of approxi-
mately 24 inches. This is far below the diameter normallypossible with a flyer for providing double twist for con-
ductor of a telecommunications cable. As shown in Figure 3,
the reels 70 and 72 are mounted one above the other upon the
support shaft 46, the support shaft having an appropriately
contoured upper surface to carry the reels under their own
weight without any other support while ensuring that they are
balanced vertically.
The upper end flange 74 of the upper reel 72 is
provided with means to prevent the conductors from dropping
down into the cylinder under their own weight and thus
prevent automatic unwinding of conductor upon stoppage in
operation of the apparatus. This holding means must operate
so as to hold the conductors upwardly while ensuring that
there is a negligible increase in the frictional resistance
to upward movement of the conductors in the cylinder 12.
This requirement is provided by a brush 76 which is arranged
around the end flange 74 by being mounted upon a support disk
78 connected to the flange as shown in Figures 3 and 6. The
13~i911~
brush 76 has bristles 80 which extend outwardly while being
inclined upwardly from the support 78 with the bristles 80
being sufficiently long so as to contact the inner surface of
the cylindrical section 16 of the cylinder 12. If required,
a similar brush may be arranged on the upper flange 74 of the
lower reel 70.
In use of the apparatus, the platform 62 is movable
horizontally from the closed position of the apparatus shown
in Figure 1 to the open position shown in Figures 4 and 5.
This action may only be made with the hinge member 30 in the
position shown diagrammatically in Figure 7, i.e. with the
hinge member 30 disposed on a diametral line which is
substantially at right angles to the direction of movement of
the platform 62. As the platform 62 moves toward the
position of Figure 4 it causes the upper domed end section 18
to rotate in one direction about the hinge member 30 while
the cylindrical section 16 rotates in the opposite direction
relative to the hinge member as shown in Figure 8. This
movement is accompanied by positional change of the hinge
member itself, from the position shown in Figure 7 to the
position shown in Figure 8, so that the upper domed end
section 18 moves away from its superimposed position upon the
cylindrical section 16. This movement of the domed end
section is permitted by relative rotation of the domed end
section through its die extension 54 within the die holder 58
by means of the bearings 56. Figure 8 illustrates an
intermediate position for the domed end section 18 (in chain-
dotted outline) with the hinge member 30 disposed at an
intermediate position between its two limiting positions of
Figures 7 and 8.
With the cylinder opened, as shown in Figures 4 and
5, the inside of the cylindrical section 16 is accessible for
mounting the reels 70 and 72 in position. The reels 70 and
72 are supported upon the top of the shaft 46 which is
suitably shaped to retain the reels balanced in position.
This is performed with the leading ends of the insulated
conductors 82 passed upwardly from the reels and located upon
the top surface of the upper reel. The platform 62 is then
13~591~8
11
moved back to its position as shown in Figure 1 to close the
apparatus. A suitable tool (not shown) is then passed down
the passage 68 and through the die 38 to draw both of the
conductors 82 up through the passage 68. It is then possible
to pass another tool through the orifice 52 to draw both
conductors from the passage 68 through the orifice 52. The
conductors are then threaded through the hinge member 30 and
through the ring or rings 32 and downwardly through the guide
passage 40, passage extension 42, and around the pulley wheel
44 to the take-up reel (not shown). Alternatively, and to
assist in drawing the conductors from the reels 70 and 72,
two diametrically opposed circular holes 84 are provided in
the domed end section 18 for passage of a human arm to grasp
the conductors (Figure 3).
The twisting operation commences by drawing the
conductors together onto the take-up reel and by rotating the
cylinder 12 with the rotating means described, the reels 70
and 72 remaining stationary by means of the gearing arrange-
ment 50. The conductors 82 are drawn axially over the ends
of the reels 70 and 72 and are unwound as they are pulled
through the die 38. With the cylinder 12 rotating, then the
conductors being lead from the reels within the cylinder tend
to balloon outwards away from the center of rotation of the
cylinder. However, the degree of ballooning is limited by
the inner surface of the cylinder against which the
conductors engage as they move upwardly, the conductors
sliding over the substantially frictionless surface towards
the die 38. As the cylinder 12 is only of sufficient
diameter to enable the conductors to pass comfortably between
the end flanges 74 and the cylinder, then the ballooning
diameter of the conductors 82 is substantially no greater
than the diameter of the flanges themselves. With ballooning
restricted in this fashion, this means that the flyer means
in the form of hinge member 30 and ring or rings 32 may be
disposed inwardly to a minimal diameter position as described
above. Upon the conductors passing through the die 38 and
proceeding through the orifice 52, they are given a single
twist around each other. The singly twisted conductors then
130~
12
proceed through the flyer means, at which some ballooning may
appear dependent upon the number and distance apart of the
rings 32, and then through the guide passage 40 and around
the pulley wheel 44 at which a second twist is provided.
At the end of the twisting operation and upon the
take-up reel becoming stationary, the conductors 82 do not
tend to drop in the cylinder 12 so that unwinding of the
conductors upon the reels and unwanted loosening of the
conductors does not result. This is because of the use of
the brush or brushes 76. As can be seen from Figure 6, when
the conductors are being drawn through the die 38, they also
move circumferentially around the inside of the cylinder 12
during unwinding. This i5 shown by the arrow in Figure 6.
This movement causes the conductors to pass across the ends
of the bristles 76 which are flexed out of the path of the
conductor. However, upon stopping operation of the machine,
the weight of the conductors immediately acts upon the
bristles to push them downwardly so that the conductors are
gripped by the inclined bristles against the inner surface of
the cylinder so as to prevent their dropping.
As can be seen, in use of the apparatus, substan-
tially all of the tension which is applied, is caused by the
frictional engagement of the conductors with the surfaces of
the cylinder and with the flyer means. The reels 70 and 72
are not rotated by the conductors as they are being unwound
so that tension is not caused by resistance to rotation of
the reels. Furthermore, no braking mechanisms are provided
with the reels nor are there any tensioning pulleys used
around which the conductors need to pass so that sudden and
jerky applications of tensile load cannot occur with the use
of this apparatus. In addition, no flybars are required for
leading the conductors over the ends of the reels and which
require the conductors themselves to rotate the flybars under
frictional resistance. It follows that the resistance to
movement of the conductors through the apparatus to the take-
up reel is exceedingly small and is substantially constant.
Hence the speed of the take-up reel may be increased or
decreased at will without increasing the load upon the
13~S~08
conductors. It has been found that conductors with extremely
small diameters, e.g. down to at least 36 AWG may be provided
with a double twist in the apparatus described in the
embodiment. In addition, in this apparatus, the cylinder 12
may be rotated at a speed of at least up to 2400 r.p.m.
without breakage of the conductors. Such a rotational speed
provides 4800 twists per minute, the pitch of which is
dependent upon the speed of take-up of the conductors.
In a modification of the embodiment, (not shown),
the gear arrangement 50 is designed so as to provide rota-
tional movement of the reels in the opposite direction to
that of the cylinder 12. This rotational movement, which of
course is not controlled by the conductors 82 themselves,
will affect the number of twists per minute.
In another modification (not shown), the cylinder
12 is located with its axis of rotation disposed horizontally
instead of vertically as described above. The design and
operation of the horizontally disposed cylinder is as
described above except that a mounting spindle is required
for locating and holding the reels inside the cylinder. This
spindle is secured to the support shaft 46.
' ',
