Terence
Anthony
Thomas
Terence
Anthony
Thomas
| 1. | A double twist stranding machine comprising a rotor (4), a cradle (10, 1 1 , 12, 19, 20) means for feeding (3) elongate elements (2) to be twisted to the rotor (4) and means for rotating the rotor (4) about the cradle (10, 1 1 , 12, 19, 20) whereby to impart a first twist to the elements (2) before the elements (2) enter the rotor (4) and a second twist to the elements (2) as they leave the rotor (4) and enter the cradle (10, 1 1 , 12, 19, 20) characterised by means for feeding (13) at least one further elongate element (16) to the cradle so that that further elongate element is wound around the first mentioned elements (2) as the second twist is imparted thereto. |
| 2. | A double twist stranding machine as claimed in claim 1 , in which the rotor (4) is supported at the axial end remote from the feed points of the first mentioned elongate elements (2) on a hollow support (8) through which the further elongate element is in operation fed. |
| 3. | A double twist stranding machine as claimed in claim 1 or 2, in which the means for feeding (3) elongate elements to be twisted to the rotor (4) comprises a lay plate and wire closing die (1 ). |
| 4. | A double twist stranding machine as claimed in claim 1 , 2 or 3, in which the means for feeding (13) at least one further elongate element (16) comprises a rotatabie tape pay off unit. |
| 5. | A double twist stranding machine as claimed in claim 4, in which the means for feeding (13) the at least one further elongate element comprises a rotatabie tape pay off unit having one or more pads of tape (16) mounted in an associated cradle (17), mounted in turn in a support (18). |
| 6. | A double twist stranding machine as claimed in claim 5, in which the rotatabie tape pay off unit is arranged to feed tape from one or more concentrically wound pads of tape. |
| 7. | A double twist stranding machine as claimed in claim 5, in which the rotatabie tape pay off unit is arranged to feed tape from one or more helically wound pads of tape. |
| 8. | A double twist stranding machine as claimed in any preceding claim, in which means are provided for rotating the means for feeding (13), the at least one further elongate element at the same speed and in the same direction as the rotor (4). |
| 9. | A double twist stranding machine as claimed in claim 8, in which the means for rotating comprises a single drive which is also operative to rotate the rotor (4). |
| 10. | A double twist stranding machine as claimed in claim 8, in which the means for rotating the means for feeding (13), and the means for rotating the rotor comprise respective drives synchronised together. |
| 11. | A double twist stranding machine as claimed in any of claims 1 to 7, in which the means for feeding (13) the at least one further elongate element (16) comprises an extension of a support for the rotor and, in operation, rotates with it. |
| 12. | A double twist stranding machine as claimed in any of claims 1 to 3, in which the means for feeding (13) the at least one further elongate element comprises a carriage having a plurality of wire bobbins (30), a lay plate (31 ) through which wires from the bobbins in operation pass and a closing die (32). |
| 13. | A double twist stranding machine as claimed in any of claims 1 to 3, in which the means for feeding (13) the at least one further elongate element comprises a multiple wire flyer pay off (40) comprising a plurality of coaxially aligned bobbins (41 ), respective flyers (42) disposed for rotation about respective bobbins (41 ), the bobbins (41 ) defining centrally disposed bores through which, in operation, respective wires from preceding bobbins to emerge as a rotating group of parallel wires (33) from the last of the bobbins (41 ). |
| 14. | A double twist stranding machine as claimed in any preceding claim, in which the cradle comprises a take up drum (12), capstan wheels (10, 1 1 ) pivotable guide pulley (19) and traversing mechanism (20). |
| 15. | A method of stranding in a double twist stranding machine comprising a rotor (4) operative to rotate about a cradle (10, 1 1 , 12, 19, including the steps of feeding a plurality of elongate elements (2) to the rotor and rotating the rotor (4) to impart a first twist to the elements (2) as they approach the rotor (4) and a second twist to the elements (2) as they leave the rotor (4) and enter the cradle characterised by feeding at least one further elongate element ( 16) to the cradle so that that further element ( 16) is wound around the plurality of elongate elements (2) as the second twist is imparted thereto. |
| 16. | 6 A method of stranding in a double twist stranding machine as claimed in claim 15, in which the means for feeding ( 13) at least one further element are rotated at the same speed and in the same direction as the means for rotating the rotor. |
| 17. | A method of stranding in a double twist stranding machine as claimed in claim 16, in which the means for feeding and the rotor are driven from the same drive means. |
| 18. | A method of stranding in a double twist stranding machine as claimed in claim 17, in which the means for feeding and the rotor are driven from respective drive means synchronised together. |
| 19. | A method of stranding in a double twist stranding machine as claimed in claims 16, 17 or 18, in which the further elongate element is a tape fed from a concentrically wound pad. |
| 20. | A method of stranding in a double twist stranding machine as claimed in claims 16, 17 or 18, in which the further elongate element is a tape fed from an helically wound pad. |
| 21. | A method of stranding in a double twist stranding machine as claimed in claims 16, 17 or 18, in which the further elongate element is a wire. |
AN ELONGATE ELEMENT IN A DOUBLE TWIST
STRANDING MACHINE OR BUNCHER
The present invention relates to apparatus for and a method of
applying an elongate element in a double twist stranding machine or
buncher.
In a double twist machine, the strand or cable receives two twists
for one revolution of the machine rotor, the first twist at the entry to the
rotor and the second twist where the strand passes from the rotor to the
cradle. Until now tapes have usually been applied from a stationary
supply onto the assembled cable before entering the rotor. The tape is
thus applied at the same lay length as the cable and receives two twists
at the same points as the cable.
The drawbacks to this method are that the tape tends to wrinkle
after the second twist and also the tape is subjected to considerable
pressure in its passage through the rotor. One method that is used to
prevent the wrinkling of the tape at the second twist point is the use of
a pretwister. Although this helps the situation, it can also cause the
tapes to loosen at the entry to the rotor which thus makes them prone to
"pushing back" .
According to one aspect of the invention, there is provided a double
twist stranding machine comprising a rotor, a cradle, means for feeding
elongate elements to be twisted to the rotor, means for rotating the rotor
about the cradle whereby to impart a first twist to the elements before the
elements enter the rotor and a second twist to the elements as they leave
the rotor and enter the cradle and means for feeding at least one further
elongate element to the cradle so that that further elongate element is
wound around the first mentioned elements as the second twist is imparted thereto.
According to another aspect of the present invention, there is
provided a method of stranding in a double twist stranding machine
comprising a rotor operative to rotate about a cradle including the steps
of feeding a plurality of elongate elements to the rotor and rotating the
rotor to impart a first twist to the elements as they approach the rotor and
a second twist to the elements as they leave the rotor and enter the
cradle and feeding at least one further elongate element to the cradle so
that that further element is wound around the plurality of elongate
elements as the second twist is imparted thereto.
In a preferred embodiment of the invention, the rotor is supported
at the axial end remote from the feed point of the first mentioned elongate
elements on a hollow support through which the further elongate element
is fed. Advantageously this hollow support comprises a stub axle. The
first mentioned elongate elements are fed to the rotor through a lay plate
and a wire closing die. The further elongate element is fed from a
rotatable tape pay off unit. This unit comprises one or more pads of tape
itself mounted in an associated cradle which in turn is rotatably mounted
in a support. This tape unit, in operation, is rotated at the same speed and
in the same direction as the rotor. For this purpose a single drive may be
provided or individual respective drives may be provided synchronised
together. Alternatively, the rotatable tape pay off unit may form an
extension of the stub axle and therefore rotate with it automatically in
which case no drive specifically for this unit is necessary. Instead of tape
the further elongate element may be wire or a group of wires. Each wire
is fed from a bobbin supported on a carriage operative to rotate at the
same speed and in the same direction as the axle or support. Where there
are a plurality of wires they are fed through a lay plate and closing die to
form a parallel group. As an alternative, the bobbins may be coaxially
arranged on the centre line of the machine and provided with respective
flyers all rotating at the same speed and in the same direction as the
axle/support. Each bobbin defines a bore through which wires from the
preceding bobbin(s) pass. In both these latter cases, after leaving the
axle/support the wires are fed through lay plates before being applied to
the first mentioned twisted elongate elements. The cradle comprises a
take up drum, capstan wheels, pivotable guide pulley and traversing
mechanism. The rotor comprises a bow including bow guide dies.
In order that the invention may be more clearly understood, several
embodiments thereof will now be described, by way of example, with
reference to the accompanying drawing, in which:-
Figure I shows a diagrammatic side eievational view of one form of
double twist machine according to the invention,
Figure 2 shows a diagrammatic perspective view of another form
of double twist machine according to the invention.
Figure 3 shows a diagrammatic perspective view of a further form
of double twist machine according to the invention,
Figure 4 shows a diagrammatic perspective view of a still further form of double twist machine according to this invention, and
Figure 5 shows a diagrammatic perspective view of a still further form of double twist machine according to the invention.
Referring to Figure I, the double twist machine according to the
invention comprises a wire closing die I, through which individual wire elements to be twisted together are fed. After leaving the die the grouped
wires 2 are directed via a series of guide rollers 3 onto a rotor indicated generally by the reference numeral 4. This rotor 4 comprises a bow 5 on which the wires 2 are supported as they pass through. The bow 5 is mounted for rotation on bearings 6 and 7 at opposite axial ends. The
bearings 7 are associated with a stub axle 8 at that end of the rotor 4 remote from the closing die I. At that axial end of the stub axle remote to the die I are disposed a rotor end guide pulley 9a and tape application guides 9b. Within the volume generated by the rotating bow 5 are disposed a pair of capstan wheels IO and II, a pivotable guide pulley 19, a take-up drum 12 and a traversing mechanism 20 which together form a
cradle.
A rotatable tape pay off unit 13 is disposed at that end of the stub axle remote from the rotor 4. The stub axle 8 defines a through bore through which tape 14 from the unit 13 passes to a point 15 at which it is
helically wound onto the twisted wires as they approach capstan wheel
II. The unit 13 comprises a pad of tape 16 mounted in a further cradle 17
which is in turn rotatably mounted in a support 18. During operation the
cradle 17 rotates at the same speed and in the same direction as the rotor
4. If desired the unit 13 can support a number of pads, the number and
material thereof being chosen having regard to the cable being produced.
Cradle 17 and rotor 4 may be driven individually by respective drive motors
(not shown) synchronised in speed and direction of rotation or by a single
drive motor through appropriate gearing (not shown). Advantageously the
drive motors are electric drive motors. The wire traversing mechanism for
traversing the wire fed to the take up reel reciprocates across the axial
width of the take-up reel 12 during the winding operation. Rotor bow
guide dies (not shown) are spaced along the bow 5.
The advantages of this machine and the proposed method of
operating it are:-
1) The tape is applied at the final twist point and thus is not
subjected to further twisting which would cause the tape to
wrinkle.
2) The tape is not subjected to the high loads due to centrifugal
force and wire tension as it passes through the rotor end,
thus damage is avoided.
3) Because the tapes are not passed through the bow, higher
speeds are possible. Tape is more susceptible to damage
than cable. Eyelets on the bow may effect tape leading
edges.
An alternative embodiment is shown in Figure 2. In this embodiment parts equivalent to the parts of the embodiment of Figure I bear the same reference numerals. The main difference between this embodiment and that of Figure I is that the rotating pay off unit 13 is
formed as an extension of the stub axle 8 and thus separate drive means for this unit are unnecessary. Rotor bow guide dies referred to but not
shown in Figure I are shown at 22 and the closing die la and lay plate lb of the die I are shown in more detail. The twin rollers 23 and traversing mechanism 20 are also more clearly shown. Rotor end bearings 6 and 7 are not shown. The same advantages are achieved as with the embodiment of Figure I.
A further embodiment is shown in Figure 3. Again equivalent parts to the embodiments of Figure I and 2 bear the same reference numerals.
In this embodiment the rotating tape supply unit 13 is replaced by a
rotating carriage (not shown) which support a plurality (in this case four) of bobbins 30 of wire. Wires from the bobbins 30 pass through a lay
plate 31 and closing die 32 before entering the bore of the stub axle 8 as a group of parallel wires 33 which rotate with the stub axle. On exit from the stub axle the wires pass through lay plates 34 and 35 before being applied to the twisted core and then pass through a closing die 36. This method of operation, produces an outer layer of wires having a lay length equal to twice the core lay length but in the same direction.
A still further embodiment is shown in Figure 4. This embodiment
is similar to that of Figure 3 in that a plurality of wires are supplied rather
than a tape to produce the outer covering of the cable. Equivalent parts
again bear the same reference numerals. A multiple wire flyer pay off
indicated generally by the reference numeral 40 is provided. This pay off
comprises a plurality of bobbins 41 (in this case three bobbins 41) arranged
with their axes coaxial with the centre line of the machine. Respective
flyers 42 are disposed for rotation about bobbins 41 and in operation
rotate at the same rotational speed and in the same direction as the rotor
of the double twist machine. The bobbins 41 define centrally disposed
bores through which wires from the preceding bobbin(s) pass until they
all emerge from the final flyer 42 as a rotating group of parallel wires 33
each separated from the next wire. The wires would then pass through
the stub axle 8 and be applied to the core strand or cable in the manner
described in relation to the embodiment of Figure 3.
The advantage of the rotating flyer supply is that the bobbins 41
not being subjected to centrifugal force could be larger and due to the
lightweight of the flyers 42 higher speeds could be achieved.
Figure 5 illustrates a still further embodiment of the invention. This
embodiment is a modification of that shown in Figure 2, in which the tape
supply unit 13 is replaced by a tape supply unit 53 arranged to supply
tape from a helically wound tape pad. Guide rollers 54 are provided to
guide the tape from the pad to the entry to the stub axle 8. In other
respects the arranged is the same as the arrangement of Figure 2
equivalent parts bearing the same reference numerals.
It will be appreciated that the above embodiments have been
described by way of example only and that many variations are possible
without departing from the scope of the invention
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