This invention relates in general to alternate reverse ^* or so-called SZ- twisting, more accurately the object of the present invention is alternate reverse twisting method to form a product, as cable or similar, composed of an inner core element and/or of alternate reversely twisted elongated ele¬ ments which can be wires, leads, optical fibers or their groups, or similar or which can be twisted as quads of wires, leads etc., by an alternate reverse twisting apparatus comprising:

- a fixed dividing means at the input end of the elements to be treated,

- to opposite directions periodically rotating twisting means at the output end of the treated elements,

- thereafter arranged pressing means, preferably a niple, for pressing the treated elements tightly against each other, and

- means for defining feedpaths of the elements to be treated, which means are arranged between said dividing and twisting means.

The object of the present invention is also an alternate reverse twisting apparatus to form a product, as cable or similar, composed of an inner core element and/or alternate reversely twisted elongated elements which can be wires, leads, optical fibers or their groups or similar or which can be twisted as quads of wires, leads etc., said apparatus comprising:

- a fixed dividing means at the input end of the elements to be treated, - to opposite directions periodically rotating twisting means at the output end of the treated elements,

- thereafter arranged pressing means, preferably a niple, for pressing said treated elements tightly against each other, and

- means for defining feedpaths of said elements to be treated, which means are arranged between said dividing and twisting means.

Further the object of the present invention is an alternate reversely twisted product, as an electric and/or optical cable, lead or similar.

Elongated elements as leads, wires or similar are conventionally in a SZ- twisting apparatus for example by means of a tracked pulling device from input sides through a first circumferentially perforated holeplate serving as a fixed dividing means and through a periodically to opposite direction rotating second circumfe.rentially perforated oscillating holeplate serving as a twisting means and thereafter into a pressing means, preferably a niple, in which the elements are pressed tightly against each other. Further can be used a"spinning device to bind the pressed elements as an alternate reversely twisted product. After the pulling device spooling takes place or the twisted product can be fed to next work phase. In this kind of a conventional SZ-twisting device it has usually been placed between the dividing and twisting means a tubular intermediate element rotating with the twisting means being centrally fixed to it as well as mounted at its opoosite end in bearings to rotate in relation to the dividing means.

This kind of a conventional arrangement includes, however, the disadvant¬ age, that the rotation speed of the intermediate element is always const¬ ant, so that twisting turns of elongated elements tends to accumulate to the end towards the twisting means, whereby the pitch of the elongated elements becomes denser and their angular deviation into the twisting mean increases. Then between the direction reverse points of the twisting direc tion the number of helics of the twisted elements is very limited being 10 at the highest also the force reguired for pulling the elements increases whereby the helics of the twisted product tends to open.

This main problem, i.e. accumulation of the elements to be twisted, great pulling force and low number of helics has previously been tried to solve by principally three different methods, however, without finding a satis- factory solution.

Firstly, according to patent publications US-3910022 and US-4414802 betwee a fixed dividing holeplate and to opposite directions periodically oscilla ting twisting holeplate has been adapted one torsion-elastic torsion pipe, the inner space of which has been divided by spacers for keeping the ele _¬ ments to be twisted apart from each other, whereby said spacers thus defin feedpats of individual elements to be twisted.

Secondly, according to public Fl-patent application 803958 and publication US-4426838 between a fixed dividing holeplate and to opposite directions periodically oscillating twisting holeplate has been adapted a torsion- elastic torsion cable, rod or wire, to which have been fixed several disk- shaped and circumferentially perforated disks spaced apart in axial direct¬ ion, whereby the opening of the perforated disks serve as guide means for individual elements to be twisted.

Thirdly, according to publications US-4426839 and SU-549943 between the fixed dividing holeplate and to opposite directions periodically oscillat¬ ing twisting holeplate have been circumferentially adapted several separate pipe or spiral means, so that the space inside each individual pipe or spi¬ ral means serves as a guide means for individual elements to be twisted. According to said US-publication the pipe means have been bound together by plates provided with circumferential openings for the pipe means, while according to the SU-publication the spiral means extend freely between dividing and twisting means.

The above-mentioned disadvantage, i.e. accumulation of elements, great pul- ling force, low number of helics and especially at high rotating speeds oc- curing so-called "skip-rope" phenomenon has also been tried to solve by a solution according to US-patent 3847190, in which the pipes defining feed¬ paths of individual elongated elements to be twisted have been arranged inside a larger cylindrical mantle tube and fixed at their one ends to a fixed dividing holeplate both at their other ends to the end flange of said rotating mantle tube. Disadvantages have also been tried to solve by the apparatus according to DΞ-publication 3404264 being an improved convention¬ al SZ-starnding apparatus which include one rigid central pipe rotating with the twisting means whereby elements to be twisted are wound around the periphery of said central pipe. The jamming effect, caused of accumulation, has been tried to solve by providing the dividing holeplate with an own rotation drive and by mounting an intermediate circumferentially perforated holeplate in bearings onto the periphery of the central pipe and providing it with own rotation drive. Thus the axial distance by which the elongated elements are wound around the central pipe can due to the rotable inter¬ mediate plate somewhat be increased, but the main problem, i.e. growing friction and low number of helics cannot yet be eliminated.

Though it has been possible by the afore-mentioned solutions to slightly reduce the accumulation tendency of the elements to be twisted as well as the adverse effects og this disadvantage the goal has not yet been achieve in a satisfactory manner. The most substantial disadvantages include.

- When a torsion-elastic pipe, inside which the elongated elements to be twisted pass, is used between dividing and twisting means the limited twisting ability of the torsion pipe restricts twisting turns of the pipe and thus also twisting turns of the elements to be twisted, whereby the reverse points in the twisting direction must be placed remarkable close t each other, which is disadvantageous.

- When a torsion cable or similar is used between dividing and twisting means and when said torsion cable is provided with several axially apart spaced perforated disks to guide individual elongated elements, said elongated elements are wound against said torsion cable. Thus it is im¬ possible to eliminate the very remarkable disadvantages, i.e. jamming factor and growing friction when the number of twisting turns to one direction increase over 10. Further can be mentioned that it is impossible to produce by this kind of method or apparatus products demanding the use of central or "core" element.

When parallel and annularly adapted means, i.e. spirals or pipes, for de¬ fining the feedpats for individual elongated elements are used between dividing and twisting means it is not possible to apply high rotational speeds for twisting, but because of sag and centrifugal force said means for defining the feedpats of elements strive to detach and also easily twist unevenly in relation to each other, which significantly impedes easy twisting and increases the probability for producing a cable unfit for it purpose.

The main object of the present invention is to provide an improved alter¬ nate reverse twisting method and apparatus, by which the above mentioned disadvantages related to previously known alternate reverse twisting met- hods and apparatus could essentially be eliminated.

This object has been achieved by the afore-mentioned alternate reverse twisting method according to the present invention so, that the elongated

elements to be twisted are drawn from said dividing means to said pressing means through torsion-elastic peripherical pipes arranged peripherically around a central pipe whereby each individual elongate element to be twisted is adapted to pass inside one of said peripherical pipes, and so that said peripherical pipes are twisted periodically in one direction several turns around and against said central pipe.

The object has also been achieved by the afore-mentioned alternate reverse twisting apparatus according to the present invention so that said means for defining the feedpaths are support and guide means for said elements to be treated and include essentially a centrally disposed central pipe and periodically to opposite directions twistable peripherical pipes (4) adapted between said dividing and twisting means so that said peripherical pipes are during each twisting stage into one direction against the periphery of said central pipe, and so, that said elements to be twisted are arranged to pass through said peripherical pipes.

The second significant object of the present invention is to produce an es¬ sentially new-looking alternate reversely twisted product in which the distance between each reverse point of twisting direction would be essen¬ tially longer than previously has been able even to imagine.

According to the present invention the new-looking alternate reversely twisted product differs from the previously known alternate reversely twisted products, in that the number of twisting turns of the individual peripherical twisted elements of said product between the reverse points o the twisting direction are between 10 to 100, preferably between 30 to 80.

The present invention is based on that genious idea that the means adapted between dividing ant twisting means are intended both to support every in¬ dividual element to be twisted and to define frigtion-free feedpath for every single element to be passed through the apparatus according the pre¬ sent invention. Due to the present invention it is now possible essentiall to increase both the number of twisting turns to both directions and the distance between the reverse points of twisting direction as well as the effective lateral distance by which the peripherical torsion-elastic pipes of the apparatus are wound around the periphery of the central pipe. Thus'

can essentially be decreased both the accumulation tendency- of the elon¬ gated elements towards the twisting means and high friction effect both high pulling force applied to the elongated elements to be twisted.

Preferred embodiments of the present invention will now be descriped by manner of example with reference to accompanying drawing in which; FIG. 1 is a side elevational view partly in cross-section of alternate reverse twisting apparatus according to the first advantageous embodiment of the present invention, FIG. 2 is a cross-sectional view of means according to one advantageous em¬ bodiment for defining the feedpats of elongated elements to be passed through the SZ-twisting apparatus, whereby said means are adapted between the dividing and twisting means, FIG. 3 is a longitudinal cross-section of means according to another advan- tageous embodiment for defining the feedpats of elongated elements to be passed through the SZ-twisting apparatus, whereby said means are adapted between the diving and twisting means,

FIG. 4 is a simplified and partly cross-sectional side view of the alter¬ nate reverse twisting apparatus according to the second advantageous embo- diment of the present invention, and

FIG. 5 is a cross-section of an advantageous fastening arrangement of a peripherical pipe adapted into one opening of the dividing and/or twisting means.

As may be seen from FIG. 1 or 4 the alternate reverse twisting apparatus, which hereafter is called as "SZ-twisting apparatus", according to the invention include;

- fixed dividing means 3 adapted to the input end of the elements 2 to be twisted, as electric and/or optical wires, leads and fibers, both partial wires or leads and quads as well groups thereof, which hereafter is called as "wires". drawn from starting spools and twisted by SZ-twisting appara¬ tus,

- periodically to opposite directions rotable twisting means 6 adapted to the output end of the wires to be twisted, as well as - support and guide means 4 and 5 arranged between the dividing and twisting means 3 and 6, which define the feedpaths for the wires 2 to be twisted.

When a SZ-twisted product is being manufactured by the SZ-twisting appa¬ ratus according to the invention the wires 2 to be twisted and a possible core element 9, which can be for instance a cable, electric or optical lead, polypropene, polystyrene or paper core wire or similar, is drawn, as already mentioned before, throuhg the dividing means 3 into the support and guide means 4 and 5 and therefrom through the twisting means 6 into press¬ ing means 7, preferably a niple having in the feeding direction of wires 2 a conically tapering opening in which the SZ-twisted wires 2 and the possible core element ^' 9 are pressed tightly against each other to form a alternate reversely twisted product 8 which can further be bound by a suitable spinning device (not shown in the accompanying drawing) to elimi¬ nate the danger og untwisting.

Both the dividing means 3 and the twisting means 6 are composed preferably of a perforated holeplate, or the like both including;

- a central opening for the central pipe 7 and the possible core element 9 to be drawn through it, and

- several circumferentially with equal distance from each other arranged, and radially from said central opening separated openings for the peri- pherical pipes 4 and wires 2 to be drawn therethrough.

In the SZ-twisting apparatus according to the first and second advantageous embodiment of the present invention shown in FIGS. 1 and 4 the fixed hole¬ plate 3 for dividing wires 2 and the possible core element 9 is stationary fastened to a first support structure of the SZ-twisting apparatus. The perforated twisting holeplate at the output end of the wires 2 and the possible core element 9 is mounted in bearings to a second support struc¬ ture of the SZ-twisting apparatus and is provided with its own rotation drive, preferably composed of an electric motor with chain, gear or belt transmission, whereby the oscillating rotation speed regulation and reversing automatics can be realized in a simple manner.

To achieve the goal of the invention the support and guide means 4 and 5, which define the feedpaths for wires 2 and for the possible core element 9, are composed of a pipe group shown in FIG, 2, whereby the pipe group in¬ clude a central pipe 5, through which is drawn the possible core element 9 of the product to be manufactured, and several peripherically the central pipe 5 surrounding both aroun it twistable peripherical pipes 4, through

which are drawn the wires 2 to be twisted.

In the SZ-twisting apparatus according to the invention said peripherical pipes 4 are thin, diameter between 5 to 20 mm preferably about 10 mm, and resilient being made of torsion-elastic material, preferably of polyamide or polytetrafluorethylene and fixed into the circumferentially arranged openings of both the dividing holeplate or holedisk and the twisting hole¬ plate or holedisk, whereby the peripherical pipes 4 form a pipe mantle around the central pipe 5. According to one preferred embodiment of the invention shown in FIG. 2 the peripherical pipes 4 are arranged side by side close to each other, so that the pipe mantle formed by individual peripherical pipes 4 extends essentially uniform around the central pipe 5. When the peripherical pipes 4 are made of e.g. polytetrafluorethylene is obtained also the advantage that sliding friction between the peripherical pipe 4 and wire 2 is extremely low which tends to facilitate the easy passing of wires 2 inside the peripherical pipe 4,

During the twisting phase of the wires 2 the peripherical pipes 4 are woun around the periphery of the central pipe 5 as a result of the rotational movement of the twisting holeplate 6. Compensate the growing tensile tress caused of this twisting the ends of the peripherical pipes 4 have been in the advantageous embodiment of the present invention fixed in their axial direction resiliently into the circumferentially existing openings in the dividing holeplate 3. Corresponding resilient connection can also be used in the end of twisting holeplate 6 adapted in circumferential openings of the same. If the SZ-twisting apparatus is used for rapid twisting of ^' thin wires, like e.g. electric leads or optical fibers, it is preferable to bin the peripherical pipes 4 elastically to each other, whereby the harmful effect caused of centrifucal forces can be totally eliminated. This can most simply be made e.g. by adapting an elastic conneting ring (not shown) around the peripherical pipes or by connecting the peripherical pipes already in their manufacturing phase together e.g. by elastic strip portions.

Because the wires 2 to be twisted pass inside the peripherical pipes 4 the are not in contact with the central pipe 5, whereby the rotating central pipe does not either cause friction impeding the drawing of wires or generate any jamming danger.

To obtain atleast 10 or even 100, preferably between 30 to 80 as used with good results in test carried out, twisting turns of the peripherical pipes 4 into one direction around the central pipe 5 each torsion-elastic peri¬ pherical pipe 4 is fastened according to the preferred embodiment of the

5 present invention shown in FIG. 5 into the circumferentially existing ope¬ nings or borings of the perforated dividing holeplate 3 and/or into the circumferentially existing openings or borings of the perforated twisting holeplate 6 (which, however is not shown in FIGS. 1 or 3), resiliently in the axial direction of its longitudinal axis both rotably around its longi-

10 tudinal axis. Due to the rotable attachment twisting of each peripherica. pipe 4 around the central pipe 5 does not cause a torsional load to the peripherical pipe 4 and due to the resilient attachment also the generating tensile load can be kept as small as possible. This kind of attachment can be obtained e.g. in such a way, that each peripherical pipe 4 is compress-

15 edly locked between conical countersurfaces of two compression locking pieces 13 and 14, whereby the outer locking piece 14 is mounted with bear¬ ings into the opening of the perforated dividing holeplate 3 (or twisting holeplate 6) to rotate around and to move axially in relation to the long¬ itudinal axis of the peripherical pipe 4. The locking can be made e.g. by a

20 wedge means 17 locking the outer piece 14 and the bearing 18. To achieve resiliency one of the locking pieces 13 or 14 (in FIG. 5 that is the inner locking piece 13) is provided with flange 16, whereby between said flange 16 and the perforated disk 3 (or 6) has been arranged resilient means 15, for example a coil spring as shown in FIG. 5, rotating with the peripheri-

25 cal pipes and collapsing when the peripherical pipes 4 are wounding around the central pipe 5, whereby too high tension of the peropherical pipes 4 can be prevented.

To achieve the goal of the invention the central pipe 5 may comprise of a 30 rigid, preferably prestressed and rotating metal pipe arranged onto support structures or of a torsion-elastic torsion pipe made e.g. of plastic-based material, preferably of polyamide, and arranged ontσ support structures.

In the embodiment shown in FIG. 1 the central pipe 5 is made of polyamide. 35 It must be emphasized that the central pipe 5 can in this embodiment also be made of metal, e.g. steel. In this embodiment the central pipe 5 is prestressed between a first and a second support structure, whereby the disadvantages due to the sag and centrifugal forces can be eliminated.

As shown in FIG. 1 the end of the central pipe 5 towards the input side of wires to be twisted is adapted into the central opening or boring of the perforated dividing holeplate 3 and is provided with a bearing arrangement 11 resisting axial load, e.g. thrust or ball bearing. To ensure the axial immobility of the central pipe 5 the outer surface of the central pipe 5 i provided with a radially extending support flange supported against the above mentioned bearing 11. As further shown in FIG. 1 the end of the cent ral pipe 5 towards the output side of wires 2 to twisted has been rigidly fastened into the central opening or boring of the perforated twisting holeplate 6. This opening is preferably conical, in which case the central pipe 5 is co pressedly locked at its outer surface by a locking piece corresponding the inner surface of said conical opening or boring. In this embodiment the rotating movements of the central pipe 5 as well as the oscillating twisting movements of the peripherical pipes 4 to opposite directions thus are achieved by means of the alternate reversely rotating twisting holeplate 6.

When the central pipe 4 is made torsion-elastic it is preferable to provid that end of the cental pipe towards the dividing holeplate 3 with own rotation drive to adjust the twisting rate of the central pipe 4, whereby it is possible to increase the effective lenght on which the wires 2 will wound inside the peripherical pipes 5 around the central pipe further it i possible by this kind of an arrangement to decrease both the accumulation tendency and the angular deviation at the end of the central pipe towards the twisting holeplate 6.

In the embodiment shown in FIG. 4 the central pipe 4 is made of metal, e.g. steel, and prestressed between a first and a second support structures (no shown). Whereby the disadvantages caused by sag and centrifugal forces can be minimized. Naturally the central pipe 4 can in this second embodiment b also made of plastic based material, e.g. polyamide.

According to this second embodiment shown in FIG. 4 the central pipe 5 is adapted centrally both to stationary dividing holeplate 3 and to alternate reversely rotating twisting holeplate 6 and mounted to rotate essentially freely and untwistingly in relation to both dividing and twisting hole- plates. In this embodiment the central pipe 5 is supported at its both ends with bearings 11 and 12, preferably thrust- or ball-type bearings resistin

axial load. The axial immobility of the central pipe 5 can in this embodi¬ ment be ensured for example by providing the outer surface of the central pipe 5 with radially extending flanges, one of which is support to the bearing 11 at the side of the dividing holeplate 3, and the other of which is supported to the bearing 12 at the side of the twisting holeplate 6. As further can be sen in FIG. 4 that end of the central pipe 5 towards the dividing holeplate 3 is provided with a rotating drive, which can be e.g. ^* an electric motor with chain, belt, gear or similar force transmission. Due to the freely, in relation to the rotational movements of the twisting holeplate 6, adjustable oscillating rotational speed as well as direction of the central pipe 5 is achieved the advantage, that the central pipe 5 can be oscillatingly rotated with different speed or even direction com¬ pared with the oscillating rotation movements of the twisting holeplate 6 and peripherical pipes 4, whereby it is possible to reduce friction between central pipe 5 and peripherical pipes 4 and spread the wounding of peri¬ pherical pipes 4 onto a longer portion of the surface of the central pipe 5. Arrangement according to this second preferred embodiment evens out the pitch of the peripherical pipes 5 wound around the central pipe 5 parti¬ cularly at that end of the central pipe towards the twisting holeplate 6 or reduces the so-called pitch error.

On one hand to prevent flattening of the peripherical pipes 4 wound around the central pipe 5, which may impede movements of the wires 2 through the peripherical pipes 4, and on the other to eliminate sliding of the peri- pherical pipes 4 axially on the surface of the central pipe 5, which may increase jamming probability, pitch eror and the accumulation of the peri¬ pherical pipes 4 especially at the side of twisting holeplate 6, the outer perimeter of the central pipe 5 is provided as shown in FIG. 3 with a resi¬ lient material layer 10, which according to one preferred embodiment of the invention is made of polyurethane and to which the peripherical pipes 4 are pressed during wounding around the central pipe 5.

When SZ-twisted product is manufactured by the SZ-twisting apparatus accor¬ ding to the present invention, which product should include a central core element 9 and SZ-twisted peripherical wires 2 surrounding peripherically the core element 9. The core element 9 which will extend to the whole lenght of the product to be manufactured is drawn through the central pipe 5 into the niple 7 simultaneously when the wires 2 to be twisted are drawn

through the peripherical pipes 4 to be wound around the central pipe 5 int the niple 7.

When the inner diameter of the central pipe 5 is selected essentially greater than the diameter of the core element 9 to be drawn therethrough, the core element 9 can be coated before the twisting holeplate 6, prefe¬ rably before the dividing holeplate 3, with an intermediate, e.g. insulat¬ ion or binding agent, layer. When said binding agent layer is used, the above mentioned binding after the niple 7 by means of thread or band for ensuring the twisting maintenance can be eliminated and the twisted wires are fastened keeping their pitch in the niple to said binding agent layer 10.

The invention has been above described only by means of some preferred em- bodiments. This is not, however, ment to limit the present invention, but several modificatons as well as variations are possible within the spirit and scope of the accompanying claims.

Thus the afore-described bearing and rotating solutions for the central pipe 5 are not naturally the only ones to achieve the goal of the present invention.

When the central pipe 5 is composed of a torsion-elastic torsion pipe it must be observed, that the bearing arrangement of the central pipe 5 at th end of the dividing holeplate 3 described in connection with the FIG. 1 is not necessary. The central pipe 5 can be adapted between the first and second support structures so that it is stationary and centrally fastened at its one end to the dividing holeplate 3 and at its other end also stationary and centrally to the twisting holeplate 6, whereby the central pipe 5 is twisted periodically to opposite directions corresponding to the oscillating rotational movement of the twisting holeplate 6.

When the central pipe has been made as torsion pipe its end towards the dividing holeplate 3 has been adapted in bearing arrangement, preferably resisting axial load, and provided with rotation drive, as an electric motor with suitable power transmission. The other end of the central pipe can then be fastened centrally and stationary to the twisting holeplate, ' whereby by changing the rotation speed or direction of that end of the

central pipe towards dividing holeplate 3 the twisting of the central pipe around its longitudinal axis can be accelerated, retarded or hold up.

In connection with the supporting of the central pipe 5 it must still be stated that in accordance with the present invention instead of the bearing arrangement resisting axial load it is possible to use a bearing arrang ent enabling an axial movement of the central pipe in relation to dividing means or twisting means. Such a bearing arrangement, by which the central pipe 5 can be adapted floatingly between dividing and twisting means, can be realized by e.g. a sliding or closed bearing mounted at that end of the central pipe which has not been stationary fastened to the twisting means rotating the central pipe or at that end of the central pipe which is not connected with the rotating drive. Such a floating central pipe is not, of course, prestressed and it can therefore be used most advantageously in solutions where large span between support structures are not required.

Furter must be stated thet the guide and support means, which define the feedpats for the wires to twisted, are not necessarily composed of separate torsion-elastic pipes as described before, but they can also be constructed of a torsion-elastic and hollow multichannel profile element, which is manufactured e.g. be extrusion, and which includes one central channel for the possible core element and several hollow peripherical channels for the wires to be twisted surrounding the central channel.

The central pipe or central channel can also be equipped with spacers de¬ fining into the inner space of the central pipe or central channel desired number of parallel feedpaths for core elements. In this case also an elon¬ gated core unit can be assembled by mutually twisted wire elements by twisting the central pipe simultaneously with the twisting of the peri- pherical pipes.