High speed cage fly-off strander

A high speed rigid strander is described that has a rotatably mounted cage which includes a plurality of bobbin support members which are parallel to and angularly spaced about the axis of rotation of the cage. Each support member includes a locking mechanism for simultaneously locking or releasing an entire row of bobbins, each of which is spaced from the axis of rotation and has its longitudinal axis oriented generally radially or at an angle normal to the strander axis. Wire guides associated with each bobbin fly the wires off the bobbins under the action of external pulling forces without requiring the bobbins to rotate. Fly-off is generally radially inwardly against the action of centrifugal forces and the wires are guided towards the strander axis and then parallel thereto so that the wires from all of the bobbins can be brought to an end of the rotating cage and wound about a core wire. Also described is a loading and unloading system which can advantageously be used with the stranders of the present invention.

BACKGROUND OF THE INVENTION 
The present invention generally relates to high speed cable or wire 
stranders, and more specifically to a high speed rigid-type cage strander 
in which the axes of the bobbins are oriented at angles substantially 
normal to the axis of rotation of the strander and wire take-off takes 
place without bobbin rotation. 
When manufacturing a cable from a plurality of wires, a core wire formed by 
either a single wire or a plurality of already stranded wires is usually 
passed through the machine and other wires are wrapped around the core 
wire either while the core wires move along its path or at the end of the 
machine. This function is usually carried out by high speed machines 
which, as a rule, include one or more rotatable frames or housings and a 
plurality of wire-carrying bobbins located within the frame or carried by 
supports mounted on the frames. 
The core wire is usually paid-off from a bobbin mounted outside the frame 
and passed through the frame through a path either along the axis of 
rotation of the frame or displaced from the axis of rotation of the frame. 
The way the core wire is handled characterizes the type of wire strander 
and its application. 
If the core wire is passed through the machine along its axis of rotation, 
the wire carrying bobbins rotate around it and the wires paid-off are 
wound on the core wire at several points along the machine. This system 
allows the manufacture of conductors with a high number of wires and a 
change in direction of the various layers since the machine is composed of 
many cage sections independent of each other. Futhermore, since the core 
wire passes substantially along the axis of the machine, a large 
multi-stranded core can be used. 
If the core wire is passed through the machine along a path significantly 
displaced from the axis of rotation of the frame, the wire carrying 
bobbins are positioned inside the frame along its axis of rotation and 
they remain stationary while the frame rotates. The cable wires are 
paid-off from the bobbins and the wires pass through a path displaced from 
the axis of rotation of the machine and are wound around the core wire at 
the end of the machine. This method allows the manufacture of conductors 
with a relatively low number of wires and the various layers of the 
stranded conductors must be wound in the same direction. 
In the past, wire carrying bobbins mounted on the frame of the strander 
have usually been mounted so that the bobbins were required to rotate 
along their longitudinal axis in order to pay-off the wire. This 
arrangement usually requires some control of the rotation of the bobbins, 
such as a brake mechanism for each bobbin to provide the required wire 
tension and to assure that the bobbins will not continue to rotate when 
the frame of the strander has stopped its rotation. 
The braking device causes the tension of the wire paid-off from the bobbins 
to vary during the operation of the strander since the wire pulling 
tension required to make the bobbin rotate is different when the bobbin is 
full or near empty. If the initial braking force is adjusted for a full 
bobbin, the same braking force applied to a bobbin with partially depleted 
wire supply is sometimes sufficient to cause unacceptable stretch, 
especially for wires of the smaller gauge. In such a case, the cable 
produced will be malformed. Also, since the braking force is applied to 
each bobbin before the initial start of the strander, there is a tendency 
to stretch the wire before the strander reaches its normal operational 
speed. Because of frequent malfunction of the brakes, the wires from the 
bobbins within the frame of the strander occasionally continue to pay-out 
after the strander has been stopped, and because different brake forces 
are applied to different bobbins, different tensions are created in the 
wire paid-out from the bobbins. Therefore, many times the cable formed by 
traditional stranders have one or more wires loosely wrapped with the 
remaining wire more tightly wrapped. 
Most known stranders being used in the manufacture of stranded cable from a 
plurality of wires have additional disadvantages. Unloading of empty 
bobbins and loading of full bobbins is normally a time consuming process 
and can result in a substantial down time of the machine. In some 
instances, bobbins must be handled individually during loading and 
unloading. At best, the prior art teaches the simultaneous loading and 
unloading of a single row of bobbins. For example, for a twenty-four 
bobbin rotor, it may take almost one half an hour to load and unload even 
with the most advanced machines. 
Safety has always been a concern with respect to stranding machines since 
they normally rotate at high speeds and carry very heavy bobbins. Failure 
of a machine which causes accidental release of a bobbin during operation 
can result in substantial personal injury and property damage. While 
numerous approaches have been proposed to minimize such accidents, many 
machines are still not sufficiently safe. 
SUMMARY OF THE INVENTION 
Accordingly, in order to overcome the above-described disadvantages 
inherent in the prior art stranding machines, as well as achieve other 
objects which will become evident from the descriptions that follow, a 
strander in accordance with the present invention comprises a longitudinal 
shaft defining the machine axis of the strander and adapted to advance a 
core wire along the length thereof. A support portion is spaced from and 
generally parallel to said shaft and mounted for rotation about said axis. 
Securing means are provided on said support portion for securing at least 
one wire-carrying bobbin to said support portion in a position displaced 
from said shaft and with the longitudinal axis of said at least one bobbin 
oriented generally radially at an angle substantially normal with respect 
to said shaft. Wire payoff means are provided for guiding the wire paid 
off from said at least one bobbin in a generally radially inward direction 
around the radially innermost end of the bobbin. The wire is then guided 
to a point proximate to said shaft which is substantially coincident with 
the longitudinal axis of said at least one bobbin and, subsequently, the 
wire is guided in a direction generally parallel to said shaft. Fly-off 
takes place under the action of external pulling forces acting on the 
wires, thus enabling the wires which are paid off the bobbins to be 
brought to an end of said shaft and wound about the core wire. 
The high speed cage fly-off strander of the present invention is extremely 
safe in operation because the bobbins, during rotation of the cage, are 
urged by centrifugal forces into pressure abutment against the support 
portion which can be a reinforced beam or support member. There are no 
locking elements which can be inadvertently released during operation of 
the strander. In fact, the higher the rotational speed of the rotating 
cage, the more secure the bobbins are against the support portion because 
of the increased frictional forces developed therebetween. 
In addition to providing a better quality strand with greater safety, the 
fly-off strander of the present invention substantially facilitates 
loading and unloading of the strander and substantially reduces the times 
required therefor. The strander includes means for simultaneously locking 
or releasing one or two rows of bobbins simultaneously so that said rows 
can be lifted out of the strander and a new set of bobbins inserted 
thereinto. For example, in a presently preferred embodiment wherein four 
rows of bobbins are angularly displaced by 90.degree. about the axis of 
rotation of the strander, diametrically opposite rows of bobbins can be 
simultaneously removed or inserted to thereby permit loading or unloading 
of the entire strander in two steps. An additional advantage obtained by 
removing diametrically opposite sets or rows of bobbins simultaneously is 
that the rotating frame of the strander is always balanced before and 
after the removal or insertion of two rows of bobbins. Being balanced, the 
rotating frame or cage of the strander can be rotated to the desired 
loading and unloading positions with a low-torque indexing device. This 
further reduces the complexity and the cost of the stranding machine. 
Other advantageous features of the invention include the fact that the 
disclosed cage strander can be designed for higher speeds than 
conventional rigid-type stranders and can accept bigger packages. These 
factors significantly increase the productivity of the subject strander. 
Also, the ability of the present strander to take off wire from stationary 
bobbins with much lower and more uniform tensions also enables the 
strander to reliably work with fine gage or low tensile wires with minimum 
breakage.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now specifically to the drawings, in which identical or similar 
parts are designated by the same reference numerals throughout, and first 
referring to FIGS. 1 and 2, a high speed cage fly-off strander in 
accordance with the present invention is generally designated by the 
reference numeral 10. 
The strander 10 includes a main frame base 12 which is secured to the floor 
or surface on which the machine is mounted by any conventional means, such 
as bolts 14. 
The strander also includes front and rear bearing stands 16, 18 
respectively which support the main or primary bearings 20, 22 which 
rotatably carry a cage or frame, generally identified by the reference 
numeral 24, for rotation about the machine or strander axis defined by the 
bearings 20 and 22. 
The cage or frame 24 includes a frame front wall 26 and a front plate 27 
mounted thereon, and a frame rear wall 28 and a rear plate 29 as shown. 
The end frame walls and plates are mounted for rotation about the bearings 
20, 22 by means of any conventional drive, which is not shown. 
Extending between the frame front and rear walls 26, 28 are four support 
portions or frame support members 30 which are spaced from and generally 
parallel to the axis of rotation of the strander, the support portions 30 
being mounted on the frame end walls for rotation about the axis of 
rotation. The frame support members 30 may be fabricated in any suitable 
manner, for example, from steel plate and may be internally reinforced by 
use of I-beams or other reinforcing members as suggested, for example, in 
FIG. 2. The frame support members 30 are advantageously welded to the 
frame and walls 26, 28 so as to form an integral rigid assembly. For 
reasons which will become more apparent hereafter, the frame support 
members 30 must be sufficiently strong to withstand the maximum 
anticipated centrifugal forces, which can be substantial, during rotation 
of the frame 24. The dimensions of the frame support members 30 as well as 
any additional reinforcements thereof such as partitions or tying members 
30' are, therefore, a function of the total weight of all the bobbins 
mounted on the support members as well as the maximum design speed of the 
cage or frame 24. 
As viewed in FIG. 2, it would be evident that by angularly displacing the 
frame support members 30 about the axis of rotation of the strander, there 
are provided a plurality of access openings 31 between adjacent support 
members 30 which can be used to load and unload the bobbins from the 
machine as will be more fully described hereafter. 
Again referring to FIG. 1, there is shown mounted on each frame support 
member 30 a plurality of bobbins 32 which are arranged in rows along the 
individual or respective support members generally in a direction parallel 
to the axis of the strander. Each bobbin is shown to have a flange 32a 
which abuts against a respective frame support member 30 and an opposing 
flange 32b which is radially inwardly spaced towards the axis of the 
machine. For reasons which will become evident, the present invention can 
also be used in conjunction with other wire-carrying devices which use 
inner flanges 32b which are smaller in diameter than the outer flanges 
32a, or which totally eliminate the inner flanges. 
The bobbins 32 are selectively releasably secured to the frame support 
members as will be more fully described below and do not rotate about 
their individual axes as with conventional stranders. 
The bobbins 32 are fixed or secured to the frame support members 30 in a 
position displaced from the axis of rotation of the machine and with the 
longitudinal axes of the bobbins oriented generally radially at an angle 
substantially normal with respect to the axis, and preferably at 
90.degree. to the axis. 
The bobbins 32 are secured to the frame support members 30 by means of 
fixed support members and movable pawls as will be more fully described in 
connection with FIG. 4. 
Referring to FIGS. 1 and 2, the strander 10 has a central shaft 38 which is 
advantageously hollow and has a central opening along the axis of rotation 
of the cage or frame 24 and is aligned with similar through openings in 
the bearings 20 and 22 to permit passage along the axis of the strander of 
a core wire 40 onto which the wires or leads which are taken off the 
bobbins 32 may be wound. 
Mounted for rotation about the axis of the strander is a low inertia 
balanced fly-off or take-off arm or guide 42 associated with each bobbin 
32. For example, the guides 42 may be mounted on an annular plate 43 or 
secured to the shaft 38 directly for rotation therewith with rotation of 
the cage or frame 24. The guides or wire payout means 42 guide the wires 
32c on the bobbins in a generally radially inward direction around the 
radially innermost end or flange 32b of the bobbin, as shown, and then to 
a point proximate to the shaft 38 at a point which is substantially 
coincident with the longitudinal axes of the respective bobbins 32. 
Subsequently, the wire 32c is advanced in a direction generally parallel 
to the shaft 38. With this arrangement, fly-off takes place under the 
action of external pulling forces acting on the wires, for example, by 
using a conventional capstan drive which pulls the stranded wire 40' 
through the stranding machine. 
The fly-off or take-off arm 42 can best be described with reference to 
FIGS. 1 and 3. Connected to the annular plate 43 is a hollow shaft 44 on 
which there is mounted a pulley wheel 46 which is fixed with relation to 
the plate 43 and rotates about the axis of the shaft 38 with rotation of 
the cage or frame 24. Mounted for rotation on the shaft 44 about an axis 
substantially normal to the axis of rotation of the strander and 
substantially coincident with the longitudinal axis of a respective bobbin 
32 is a fly-off assembly 48. 
Mounted on the fly-off assembly 48, as best shown in FIGS. 1-3, is a 
fly-off arm 52 and a plurality of balancing arms 54 which, in the 
presently preferred embodiment are arranged at right angles to each other 
as shown. While more than four cooperating arms can be used, it has been 
found that at least four arms are required to provide balancing. Weights 
55 may be provided at the ends of the balancing arms 54 which are selected 
to optimize balancing and assure smooth rotation and operation of the 
guide 42. The balancing arms 54 should be approximately the same length as 
the fly-off arm 52 to compensate for any preferential movements of the 
guide 42 during rotation. 
If there is any possible interference of the arms on adjacent fly-off 
guides 42, the weights 55 may be suitably shaped as triangular wedges as 
shown in FIGS. 1 and 2 to assure clearance between the balancing arms in 
the worst condition when the balancing arms are in a common plane and 
adjacent to each other. Of course, during the actual operation of the 
machine, the fly-off and balancing arms 52, 54 will be randomly disposed 
about the respective individual axes of the bobbins so that interference 
would normally be avoided in most instances. 
The length of the fly-off arm 52 is selected to be greater than the maximum 
radius of bobbin contemplated to be used with the strander. In this 
manner, a supporting bracket 56 projects radially outwardly from the 
fly-off arm 52 to an intermediate point along the bobbin and carries two 
radially spaced pulley wheels 58, 60 which simultaneously, together with 
the pulley 50, rotate about the axis of a respective bobbin 32 and shaft 
44 as a wire 32c is caused to fly off a bobbin. 
Referring to FIG. 3, there is shown in dashed outline the barrel 62 of the 
bobbin, the diameter of the barrel also corresponding to the diameter of 
the wire being drawn off at the time when the bobbin is substantially 
empty. The dashed circular line 64 corresponds to the diameter of the wire 
roll when the bobbin is full. The pulley wheel 60 is positioned 
approximately midway between the flanges 32a and 32b and is oriented as 
best shown in FIG. 3 to accept wire from the bobbin when the same is 
either full or almost empty. To minimize the possibility of wire escaping 
or leaving the groove of the pulley wheel 60, the same is advantageously 
oriented along a line coinciding with the median position 66 of the wire 
which is a position midway between the bobbin being full and empty. If 
desired, the pulley 60 can be slightly moved to one side or the other side 
of the median 66 to still further minimize escape of the wire from the 
pulley wheel 60 when the wire is taken from one side of the median 66. In 
that case, however, the likelihood of separation becomes greater when wire 
is drawn from the opposite side of the median 66. To prevent such 
separation, however, a suitable guard plate or stop member adjacent to the 
pulley wheel 60 may be provided to avoid escape of the wire. 
Since the fly-off assembly 48 is rotatably mounted on the shaft 44 by 
means, for example, of a bearing, there is a minimum or inherent amount of 
friction during rotation of the take-off arm or guide 42. This minimum 
friction can, of course, be increased by a suitable brake, to be 
described, to assure proper tensioning and controlled fly-off of the wire 
from the bobbins 32. 
The fly-off or take-off arm or guide 42, then, serves to initially receive 
the wire 32c on the pulley wheel 60, the pulley wheels 58 and 60 being 
arranged relative to each other to cause the wire to advance in a 
direction generally radially inwardly to a point on the other side of the 
fly-off and balancing arm arrangement so that the wire can be brought to a 
point, by means of pulley wheel 50, which is substantially coincident with 
the longitudinal axis of the bobbin 32 and the shaft 44. The wire 32c 
advances along the axis of the shaft 44 and its direction of movement is 
changed by 90.degree. by the pulley wheel 46 mounted on the shaft 44 so as 
to bring the advancing wire to a point proximate to the shaft 38 in a 
direction parallel to the axis of the strander. The wires from all the 
bobbins 32 are caused to fly-off in the same manner and all the wires are 
brought to points proximate to and parallel to the shaft 38. All the wires 
about the shaft 38 are pulled out of the end of the strander and wound 
about the core wire 40'. 
While the friction of the bearing in the fly-off assembly 48 may be 
sufficient for some purposes, it may be desirable in some cases to 
increase the tension on the wire during fly-off. This can be accomplished 
by simply providing a suitable braking mechanism which applies an 
adjustable braking force on the housing of the fly-off assembly 48. For 
example, as shown in FIG. 2, there is shown a clamping arrangement which 
is fixedly mounted on the support plate 43 and is provided with a screw 
adjustment for applying a variable pressure on a pair of clamping bars 71 
which may include suitable pads. In this manner, a continuously adjustable 
braking force can be applied to the housing of the fly-off assembly 48 and 
thus the tension applied to the wire during fly-off can be controlled. 
An important feature of the present invention is that the bobbins 32 are 
fixedly mounted to the frame support members 30 to that they do not rotate 
about their axes during the operation of the strander. In this connection, 
any suitable securing means may be provided on the support members or 
support portions 30 for securing the bobbins 32 thereto. Referring 
particularly to FIG. 4, the securing means is shown to include a plurality 
of support members 72, 74, 76 and 78 which are configurated and arranged 
to selectively engage the flange 32a of the bobbin which is in abutment 
against the respective support member 30 to release that flange in a 
direction substantially transversely to both the support member 30 itself 
as well as to a direction radial with respect to the axis of the strander. 
With the support member 30 positioned as shown in FIG. 4, two of the 
support members 74 and 76 are advantageously positioned along a 
substantially horizontally directed line. An additional support member 72 
is provided which is disposed below and generally more proximate to the 
fixed support member 76. The support members 72, 74 and 76 may be fixed 
permamently or by bolts to the support member 30 and movable along slots 
to accommodate the periphery of the flange 32a, as shown in FIG. 4A, as 
well as bobbins having different flange diameters. 
The support members 72, 74, 76 generally define a circle having a diameter 
which is somewhat greater than the diameter of the flange 32a, so that 
when the bobbin is held as shown in FIG. 4, there is some clearance to 
permit some play of the bobbin between the supports. The fixed support 
members 74 and 76, in essence, initially guide the flange 32a to 
facilitate mounting of the flange 32a and removal of the flange from the 
support member 30. When the bobbin is fully lowered to the position shown 
in FIG. 4, it rests on the lower fixed support 72 and on the lateral 
support 74, the other lateral support 76 functioning primarily as a guide 
during insertion. 
At least one of the support members is in the nature of a pawl 78 which is 
movable between locking and releasing positions so as to lock and release 
the bobbin during the loading and unloading operation. The mounting or 
securing means shown in FIG. 4 for one bobbin is repeated for each bobbin 
along the length of the support member. One advantageous feature of the 
invention is that it is possible to use a locking or actuating mechanism 
for simultaneously moving the movable pawls 78 for all the bobbins mounted 
on a common support portion or support member 30 to thereby simultaneously 
release or lock the bobbins supported thereon and permit the simultaneous 
insertion or removal of an entire row of bobbins on a support portion 30. 
The movable pawl 78, in the locking position thereof, advances in the 
direction of the flange 32a and urges the flange against the fixed support 
members 72 and 74, forming a three point contact system, wherein the 
flange 32a is fixedly secured at three points uniformly about the 
periphery thereof. With this arrangement, wherein the support members are 
distributed about the periphery of the flange 32a, only the movable pawl 
78 can be positioned in the path of removal or insertion of the bobbin 
into the strander. Referring to FIGS. 4 and 4B, the pawl 78 may be 
retracted into a slot 78' of the frame support member 30 during loading 
and unloading so as not to interfere with the free movements of the 
bobbin. 
The specific locking mechanism 80 used is not critical for purposes of the 
present invention. However, it is desirable that single actuation thereof 
automatically moves all the pawls 78 on a single support member 30 to the 
locking or releasing position. Referring to FIG. 5, there is shown one 
approach to obtain such simultaneous actuation. Formed in the front plate 
27 is a pair of rectangular slots or openings 82, 84 each associated and 
in registry with another frame support member 30. The cage or frame 24 is 
rotated to a loading position as shown in FIG. 5, where two diametrically 
opposing support members 30 are disposed in a generally horizontal plane 
and two other support member 30 in a vertical plane to position the 
openings 82 and 84 in alignment with a plurality of pistons 86, 88 mounted 
on the front bearing stand 16. The pistons 86, 88 may be actuated and 
moved through the openings 82 and 84 in the front plate 27 by suitable 
actuation of a reel locking cylinder actuator 90. With this arrangement, 
for example, insertion of the pistons 86 through the openings 82 and 84 
actuates the locking mechanism 80 to move the pawls 78 from one position 
to another while insertion of the pistons 88 returns the pawls to their 
original position. The pistons 86 can, for example, be used to lock the 
pawls and the pistons 88 can be used to unlock the same. As noted, the 
specific arrangement of the locking mechanism 80 is not critical so long 
as it can positively lock the pawls 78 when moved by one of the pistons 86 
or 88. Advantageously, however, the pawls are spring biased in their 
locking positions so as to prevent chattering during low speed operation 
of the strander. As a practical matter, however, the securing means 
including the support members 72, 74, 76 and 78 primarily come into play 
during loading and unloading and at very low rotational speeds of the 
strander. Once the angular velocity of the cage or frame 24 reaches its 
operational speed, the bobbins 32 are urged outwardly against the support 
members by reason of the centrifugal forces so that the frictional forces 
which develop between the flanges 32a and the support members 30 are more 
than sufficient to prevent relative movement therebetween. In this sense, 
unlike prior art stranders, the higher the speed of the strander, the more 
secure the bobbins and the less danger of accidental release of the 
bobbins. 
Still referring to FIG. 5, once the bobbins have been inserted or mounted 
on two support members arranged in a horizontal plane and the 
corresponding pawls have been moved to the locking positions, the cage or 
frame 24 can be rotated 90.degree. to position the openings 92 and 94 
associated with the other two support members in alignment with the 
pistons 86 and 88. Again, the actuator 90 may be suitably energized to 
release or lock the bobbins in place as may be required. It will be 
evident from this discussion that the loading and unloading operation 
requires only two angular positions of the frame or cage 24 to lock and 
release all of the bobbins in the machine. 
As will be more fully discussed below, an important feature of the present 
invention, when the bobbins are mounted in pairs which are arranged on 
diametrically opposite sides of the axis of rotation, is that the cage is 
always balanced. No preferential movements are exhibited as long as 
bobbins are mounted on all of the frame support members 30 or when 
diametrically opposite rows of bobbins are simultaneously removed. This, 
therefore, includes stranders which support two diametrically opposite 
pairs of rows, or which carry two, three or more pairs of diametrically 
opposite rows. Because the cage 28 is normally balanced, positioning the 
openings in the front plate 27 into alignment with the pistons 86, 88 can 
be achieved with a low torque indexing means of any conventional type. 
Such indexing means can utilize electronic sensing means which 
automatically stops the cage or frame 24 precisely at the required 
alignment positions for loading and unloading of the bobbins and locking 
and releasing the pawls 78. 
Referring particularly to FIG. 9, the front bearing stand 16 includes a 
conventional lay plate 96 for properly positioning the individual strands 
which have been removed from the bobbins for entry into a die which is 
mounted on a die-positioning mechanism 98. Upstream of the die positioning 
mechanism 98 there is typically provided a capstan drive which applies 
pulling forces on the stranded wire 40' and, therefore, on the individual 
strands to cause the same to fly off the bobbins 32 with attendant 
rotation of the fly-off arms or guides 42. 
Referring to FIG. 1, a brake disc 102 is rigidly secured to the cage 24 by 
means of spacer mounts 104 as shown. A conventional brake disc assembly 
106 receives a portion of the periphery of the brake disc 102 for 
selectively braking the disc and, therefore, the cage 24 in a conventional 
manner. 
While the grame support member 30 in the embodiment shown in FIGS. 1 and 2 
are arranged in pairs, with each pair or frame members being disposed on 
diametrically opposite sides of the strander axis, with the longitudinal 
axes of the corresponding bobbins passing through the strander axis, 
another embodiment 108 of the strander is shown in FIG. 6. Here, the 
support members 110 and 112 are each offset on opposite sides of the 
strander axis, as viewed in FIG. 6, to cause the axis of each of the 
respective bobbins mounted on the support members to be offset from the 
axis of rotation of the strander. With the embodiment of FIGS. 1 and 2, 
the fly-off devices or guides 42 are mounted radially outwardly of the 
shaft 38, while the guides 42 and bobbins are moved radially inwardly to 
the sides of the shaft in FIG. 6. Besides resulting in a more compact 
strander, the embodiment 108 of FIG. 6 lowers the centrifugal forces 
acting on the bobbins, the wire and the take-off guides 42 with attendant 
decreases in frictional forces between the fixed shafts 44 and the fly-off 
assemblies 48. The reduction of centrifugal forces in this manner results 
in reduced tensions being applied to the wires being flown off. 
Accordingly, the embodiment shown in FIG. 6 can be used in connection with 
finer wires or, for the same gauge wire, higher rotational speeds can be 
used. However, the arrangement shown in FIG. 6 is limited to only one pair 
of opposing bobbins in a plane, as opposed to the four bobbins in a plane 
possible with the originally disclosed embodiment. 
Referring to FIG. 7, still another embodiment 114 of the invention is 
shown, wherein three frame support members are provided and angularly 
spaced from each other about the axis of the shaft by 120.degree.. With 
this embodiment, only three bobbins are mounted in a common plane 
transverse to the axis of the strander. Otherwise, the operation of the 
stranders shown in FIGS. 6 and 7 is identical to that of the strander 10 
shown in FIGS. 1 and 2. While the stranders 10 and 108 have the above 
described advantage that they are always balanced in any normal condition 
of loading and unloading, this is not the case for the strander 114 shown 
in FIG. 7. Here, only one row of bobbins can be removed from one of the 
frame support members 30, this instantaneously unbalancing the entire cage 
until such time that the other two rows of bobbins have also been removed. 
The strander 114, therefore, is only balanced when it is fully loaded or 
unloaded. Positioning the strander 114 into the loading and unloading 
positions for each support member 30 requires a higher torque drive than 
that required for the other described stranders which remain balanced. 
In FIG. 8, there is shown a bobbin having a slightly modified winding cross 
section. Instead of having a uniform winding diameter along the 
longitudinal axis thereof the winding diameter is maximum at the flange 
32a and minimum at the flange 32b, having a generally uniformly changing 
diameter therebetween. While the taper on the winding is shown somewhat 
exaggerated to facilitate illustration, the difference in diameters can, 
for example, be typically one inch on a fourteen to fifteen inch height 
bobbin. The purpose of such taper is to prevent shifting of the turns in 
response to centrifugal forces acting on the wire during rotation of the 
cage about its axis. With the uniformly wound bobbins, there is sometimes 
a tendency, particularly with low gauge wire, for individual turns to be 
thrown outwardly at high rotational speeds, especially when the bobbins 
are loosely wound. Such riding or shifting of the turns may tangle the 
wires and cause breakage during take-off or fly-off by the guide 42. By 
providing a slight taper as shown in FIG. 8, with the larger diameter 
positioned at the flange 32a which is mounted on the frame support member 
30, or at the radially outermost position, it has been observed that such 
undesired shifting of turns is avoided. 
Also shown in FIG. 8 is a smooth ring 116 mounted on the innermost flange 
32b. The smooth ring 116 may be optionally used in place of the fly-off 
arms or guides 42, particularly when the wires on the bobbins are to be 
flown off at low tension. In such cases, even the relatively small tension 
resulting from the inherent friction in the fly-off arms or guides may be 
too large. The wire 32c, rides along the outer smooth periphery of the 
ring 116 and can then be received, for example, directly in an axial 
opening of the shaft 44 and removed along the shaft 38 by means of the 
pulleys 46 proximate to that shaft. 
In some instances, the stranders of the present invention can be used in 
conjunction with bobbins which do not have an innermost flange 32b, but 
only an outermost flange 32a which is used to secure the bobbin as above 
described. In such cases, however, special handling of the bobbins is 
required. 
As suggested, an important feature of the present invention is that it 
permits greatly simplified and more efficient loading and unloading of 
bobbins. Referring to FIG. 9, the strander 10 is illustrated in 
conjunction with a loading-unloading system generally designated by the 
reference numeral 120. The system includes horizontal I-beams 124 which 
are mounted on vertical support columns (not shown). Mounted for movement 
along the beams 124 are trolley assemblies 126 which may be controlled by 
a transverse drive 128 to move along the beams between positions over the 
strander 10 and a bobbin station 122. 
Fixed to the trolley assemblies 126 is a horizontal support beam 130 and 
two vertical lifting racks 132. A gripper support frame 134 is movably 
mounted along the vertical direction by means of lifting rack and pinion 
assemblies 136 which are controlled by a lifting drive 138. Actuating of 
the lifting drive is effective to raise or lower the support frame 134 
along the lifting racks 132. 
Mounted on the support frame 134 are a plurality of reel grippers 140. The 
grippers 140 are provided on the frame 134 on each side of the support 
beam 130 as shown, the spacing between the grippers 140 corresponding to 
the spacing of the bobbins when mounted in the strander 10. 
As should be clear, appropriate actuation of the transverse drive 128 and 
lifting drive 138 can lower the reel grippers 140 at the bobbin station 
122 or at the strander 10. The construction of the reel grippers is not 
critical and may, for example, be pneumatically or hydraulically actuated 
to grip a pair of flanges of the bobbin as suggested in FIG. 2. For this 
reason, the peripheral edges of the bobbins extend beyond the frame 
supporting members so that they may be engaged by the grippers 140 and 
removed from the strander once the movable pawls have been moved to their 
unlocking or retracted positions. With this arrangement, replacing four 
rows of empty bobbins with full ones can take as little as ten minutes or 
less. In addition to such reduced loading and unloading times, however, 
the overall production and efficiency of the machine in accordance with 
the present invention is enhanced as a result of its ability to accept 
larger bobbins which, therefore, permits continuous running of the machine 
with little interruption. 
The further advantage of the present invention is the ability of the 
strander to handle wire at lower tension than conventional machines. The 
strander of the present invention allows the user to operate the machine 
at a higher speed with the same size wire or at the same speed with much 
larger packages and therefore higher productivity. This is achieved 
because contrary to the present state of the art the braking system on the 
fly-off arm is independent from the bobbin on which the wire is wound. The 
tension on the wire is constant throughout the entire production run and 
can be set at lower values because the fly-off arm is positioned very 
close to the axis of the strander and therefore is subject to a lower 
amount of centrifugal force. The strander of the present invention allows 
productivity gains of the order of four to ten times the production rates 
achieved with state of the art machines. 
It is to be understood that the foregoing description of the various 
embodiments illustrated herein is exemplary and various modifications to 
the embodiments shown herein may be made without departing from the spirit 
and scope of the invention.