WO1995004185A1

WO1995004185A1 - Apparatus for and a method of applying an elongate element in a double twist stranding machine or buncher

Info

Publication number: WO1995004185A1
Application number: PCT/GB1994/001653
Authority: WO
Inventors: Terence Anthony Thomas Pettitt
Original assignee: Northampton Machinery Co Ltd
Current assignee: Northampton Machinery Co Ltd
Priority date: 1993-07-31
Filing date: 1994-07-29
Publication date: 1995-02-09
Anticipated expiration: 1996-01-31
Also published as: AU7235994A; GB9315907D0

Abstract

In apparatus for and a method of applying an elongate element in a double twist stranding machine, tape (14) is fed from a tape pad (16) axially through a stub axle (8) to be applied to a twisted plurality of wires (2) at the point at which a second of two twists is applied by means of a rotor (4) rotating about a cradle. As the tape is applied at the second and final twist point it is not subjected to further twisting which could cause it to wrinkle. Nor is it subjected to high centrifugal forces as it passes through the rotor (4). The tape may be fed from a concentrically wound or helically wound pad. Alternatively, the tape may be replaced by wires supplied from bobbins.

Description

APPARATUS FOR AND A METHOD OF APPLYING

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

Claims

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,

20) 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.

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.