The present invention relates to an apparatus for detwisting wires or cables wound in spools.

The sector to which the invention relates is that of industrial plant and equipment for the production of cables and of multipolar insulated wires, where a twist is to be imposed on wires or cables being unwound from a spool, for example in preparation for a subsequent step of stranding, so that the wires or cables are brought together, partially or completely free from twists, in order to form a stranded product to be wound onto a collection spool.

The stranding line comprises a rotating winder, the collection spool of which rotates inside a structure which also rotates about the same axis and is known in the sector as a "rotor" or "flyer". The rotation of the flyer/spool system produces a twist of the stranded cable for each single turn of the flyer (whence the term "single-twist strander"). Each twist of the final product, thus stranded, causes an identical twist on each single element that goes to make it up. The single twists, if not partially attenuated or completely compensated, will induce residual voltages inside the stranded cable, which will compromise the mechanical and electrical qualities of the cable itself.

In order to obtain a stranded end product with particular electrical and mechanical characteristics, it is necessary to detwist every component of it during the step of unwinding from the spool of origin that precedes the stranding. The end result, i.e. at the end of the process that comprises both the detwisting and the single-twist stranding, is devoid of residual internal twists.

Apparatuses like detwisting unwinders impose an axial rotation on wires and cables that make up the final cable, in the same direction with which the strander rotates it during the process for their stranding. Nowadays three types of apparatuses are known for detwisting wires and cables.

In a first type of apparatus, the detwisting occurs through the rotation of a flyer, substantially a rotating cage, inside which a spool is provided, which in turn rotates about an axis perpendicular to the rotation axis of the flyer. Therefore the axis that imposes the rotation of the cable (or wire) is perpendicular to the axis of unwinding of the spool. The tension on the cable is controlled by adjusting the motor that actuates the spool, with suitable control of the torque, or by way of a "take-up" system for tensioning the cable, which is positioned outside the exit point of the cable from the system and is fixed with respect to the rotation of the system itself. The presence of non-rotating elements at the exit point of the system (bushings and guide pulleys) tends to disturb the twists imposed by the apparatus, thus negatively influencing the quality of the final product. Owing to the gyroscopic effect on the axis of the spool, moments are generated that are perpendicular to the rotation axes, i.e. overturning moments, such that the structures and the supporting shafts need to be strong and heavy, to the detriment of the speed of the system. Furthermore, owing to the rotation effect, considerable unbalancing forces are created which further penalize performance with consequent loss of productivity. This solution therefore has low rotation speeds and, as a result, low productivity.

In a second type of apparatus, the axis of the flyer, which imposes the rotation on the cable, and the axis of unwinding the spool coincide. Adjustment of the tension on the cable is controlled passively, using a mechanical or electric brake, or actively, by adjusting the torque of the motor that makes the spool rotate. In the first case, when the rotation speed increases the spool becomes ungovernable, owing to its inertia, and tends to maintain its state of rotation, and the brake cannot decelerate it. In the second case, although the inertia of the spool is partially controlled, the system does not have sufficient sensitivity to control low unwinding tensions of the cable. Owing to the progressive variation of the inertia of the spool, which is due to the weight changing as it is emptied, modulating the torque of the motor is not always effective.

The third type of apparatus overcomes the above drawbacks. In this case the rotation axes of the spool and of the flyer coincide and there is a system for tensioning the cable of the "take-up" type, which is arranged downstream of the flyer and is integral in rotation with it. The "take-up" tensioning system is constituted by two groups of pulleys around which the conductor is made to pass, one group fixed and the other mobile on guides and pushed by a cylinder, and is adapted to impose a twist on the cable which is configurable using a proportional pneumatic valve. Such system, although effective in tensioning the cable at low rotation speeds, loses precision as the speed increases.

In general, for all the types of apparatuses described above, rotation speeds, assuming collection spools 500 mm in diameter, are typically limited to between 250 rpm and 500 rpm. For larger sized spools, owing to the considerable rotating masses and as a result of centrifugal forces, speeds are reduced further.

The aim of the present invention is to provide an apparatus for detwisting wires or cables which is capable of improving the known art in one or more of the above mentioned aspects.

Within this aim, an object of the invention is to provide an apparatus for detwisting wires or cables wound in spools, which is capable of operating at higher rotation speeds than conventional machines, thus increasing productivity.

Another object of the invention is to provide an apparatus that is capable of containing the induced moments to the rotating part, limiting and compensating for the deformations of the structure, while still allowing relatively high rotation speeds. A further object of the invention is to provide an apparatus that operates independently of the weight and consequently of the inertias of the spools, so as to obtain a more precise tensioning of the cable with respect to the known art.

Another object of the invention is to limit the wear and tear of the mechanical elements.

Another object of the invention is to provide an apparatus that offers reduced space occupation.

Another object of the invention is to provide an apparatus that is adapted to different sizes of spools.

Another object of the invention is to provide an apparatus with which to carry out a detwisting with instant and effective control of the pull tension of the wire or of the cable, such apparatus being at the same time relieved of the force of unwinding, thus being suitable also for unwinding wires and cables that are delicate and have low characteristics of mechanical strength.

Furthermore, the present invention sets out to overcome the drawbacks of the background art in a manner that is alternative to any existing solutions.

Another object of the invention is to provide an apparatus that is highly reliable, easy to implement and of low cost.

This aim and these and other objects which will become better apparent hereinafter are achieved by an apparatus for detwisting wires or cables wound in spools, which is characterized in that it comprises:

- two coaxial shafts, inserted one inside the other and kinematically independent, a first shaft thereof is connected to first motor means and is adapted to support, by rotating it about a rotation axis, one of said spools, and a second shaft is connected to second motor means and supports, by rotating it about said rotation axis, a detwisting cage, which is adapted to rotate about said spool with at least one guide for said wire or cable that is being unwound from said spool,

- at least one take-up guide for said wire or cable, which is connected to third motor means in order to rotate about said rotation axis of said cage, oscillating toward said at least one guide and/or away therefrom,

- means for coordination of the rotation speed of said first shaft with the rotation speed of said take-up guide.

Further characteristics and advantages of the invention will become better apparent from the description of a preferred, but not exclusive, embodiment of the apparatus according to the invention, which is illustrated by way of non-limiting example in the accompanying drawings wherein:

- Figure 1 is a perspective view of an apparatus according to the invention;

- Figure 2 is a side view of an apparatus according to the invention;

- Figure 3 is a longitudinal cross-sectional view of an apparatus according to the invention;

- Figure 4 is a perspective view, like Figure 1, of another embodiment of the apparatus according to the invention.

With reference to the figures, the apparatus according to the invention, generally designated by the reference numeral 10 in a first embodiment and with 110 in a second embodiment, is designed for detwisting wires or cables 14 wound on spools 13 and comprises two coaxial shafts 11 and 12, inserted one inside the other and kinematically independent. The shafts can be seen in the cross-sectional view of Figure 3. From this point onward in the description reference will be made to a cable 14, but the apparatus 10, 110 is also adapted for detwisting a wire.

A first shaft 11 of these is connected to first motor means, not shown in the illustrations and substantially comprising a motor to which the shaft 11 is connected via a belt transmission, of which the pulley 1 la is indicated. The first shaft 11 is adapted to support, by rotating it about a rotation axis X, a spool 13. The spool 13, although not part of the apparatus 10, 110 according to the invention, is shown in Figure 1, in Figure 2 and in Figure 4 in order to facilitate comprehension of the operation of the apparatus.

The second shaft 12 is connected to second motor means, also not shown for the sake of simplicity and comprising a motor to which the shaft 12 is connected via a belt transmission, of which the pulleys 12a are shown. The second shaft 12 supports, by rotating it about the X axis, a detwisting cage 15, which is adapted to rotate about the spool 13 with at least one guide 16, 116 for the cable 14 that is being unwound from spool 13.

The apparatus 10, 110 also comprises a take-up guide 17, 117 for the wire/cable 14, which is connected to third motor means in order to rotate about the rotation axis X of the cage 15, oscillating toward the guide 16, 116 and/or away from it, and comprises means for coordination of the rotation speed of the first shaft 11 with the rotation speed of the take-up guide 17, 117.

The take-up guide 17, 117 is mounted so as to rotate substantially on the same circumference of rotation of the guides 16, 116.

In a possible embodiment, not shown, the take-up guide is constituted by a pulley and the other guides by rollers.

In the example shown for the first embodiment of the apparatus 10, the take-up guide 17 and the guide 16 are constituted by rollers. There are two take-up guides 17 and there can be up to four guides 16. Each take-up guide 17 is mounted between two simple guides 16, in the manner that will become clearer below.

Figure 4 shows the second embodiment 110, where there is one takeup guide 117 (described below) and one guide 116 (also described below). There is also a similar take-up guide 117 in a position diametrically opposite to the first.

The first shaft 11 and the second shaft 12 are tubular and are inserted one inside the other and are rendered kinetically independent by means of the interposition of first bearings 18 and of second bearings 19. The first shaft 11 is more internal with respect to the second shaft 12.

At one of the ends, the first shaft 11 ends with a respective first flange 22 at which a supporting disk 23 for the spool 13 is mounted. The supporting disk 23 is conveniently perforated for the axial mounting of a tubular element 24 on which the spool 13, through its through hole, can be inserted.

The first shaft 11, extended by the tubular element 24, is mounted so as to contain a retention shaft 20 for the spool 13, which protrudes from both ends of the first shaft 11. On the protruding portion on the opposite side from the side on which the spool 13 is mounted, a helical spring 21 is mounted which is adapted for the axial traction of the retention shaft 20.

A disk-like element 25 can be associated with the end of the shaft 20 protruding on the spool side, in order to retain, through the axial thrust of the spring 21, the spool 13 resting against the disk 23.

To control the axial thrust of the spring 21, the first shaft 11 has a closure element 26 which is perforated for the passage of the shaft 20. On the same side, at the end of the shaft 20, a screw 27 is screwed, and on it a ring 28 is screwed, locked by nuts 29. The helical spring 21, mounted on the end of the shaft 20, between the closure element 26 and the ring 28, determines with its thrust the compression force of the spool toward the disk 23.

The first pulley 11 a is mounted proximate to the end of the first shaft 11, at the opposite end to that of the first flange 22. The first pulley I la is toothed, as can also be seen from the perspective view of Figure 1, for meshing with a toothed belt which takes the rotary motion from a driving pulley at a first motor of the first motor means.

Proximate to the first pulley I la there are two pulleys 12a mounted on the second shaft 12, to be associated with respective belts which take the rotary motion from the driving pulleys at a second motor of the above mentioned second motor means. Multiple apparatuses 10, 110 can be used for detwisting multiple cables to be brought to a strander. If detwisting of a single cable is required, then with a single apparatus 10, 110 there is a single pulley 12a.

At the opposite end to the end where the second pulley 12a is provided, the second shaft 12 also ends with a flange, which from this point onward is indicated as a second flange 30, with which the cage 15 is integrally associated.

The third motor means comprise a third pulley 31 , toothed, mounted on the second shaft 12, which is more external than the first shaft 11, and rendered kinematically independent of this by the interposition of third bearings 32 and rendered integral with a frame that supports the take-up guides 17, 117 as will become clearer below.

The toothed third pulley 31 can be associated with a respective toothed belt which takes the rotary motion from a driving pulley at a third motor of the third motor means.

The apparatus 10, 110 also conveniently comprises a mounting element 33 which is associated with the rest of the apparatus and is fitted on the second shaft 12 with the interposition of fourth bearings 34. This mounting element 33 has a flange with which a supporting structure, on which the apparatus 10, 110 can be installed, is rendered integral with, by bolting. The presence of the fourth bearings 34 makes possible the rotation of the rest of the apparatus 10, 110 with respect to the mounting element 33.

The cage 15 comprises a first frame 35 with a pair of first sides 36 which are perpendicular to the rotation axis X and are connected by first tension members 37. Each guide 16, 116, as well as the tension members 37, is interposed between the pair of first sides 36. Each take-up guide 17, 117 is mounted on a second frame 38, in the first embodiment of the apparatus 10 is mounted between a pair of second sides 39 on planes that are parallel to the first sides 36 and which are connected by second tension members 40. In the second embodiment of the apparatus 110, it is instead, preferably, fitted cantilevered from a second side 39 of the second frame 38. The second frame 38 has a single side 39. The second frame 38 is adapted to rotate in a kinematically independent manner with respect to the cage 15 and therefore kinematically independent of the first frame 35.

In an alternative form, not shown, the first embodiment can also have the second frame having a single second side and the take-up guides mounted cantilevered.

The first sides 36 and the second sides 39 are constituted by ring elements.

The apparatus 10, 110 comprises means for arresting the oscillation 41 of the take-up guide 17.

In the first embodiment 10, the take-up guide 17 is mounted, with the interposition of bearings 42, on a longitudinal support 43 (indicated in the cross-sectional view) which is installed between the second sides 39, in particular coupled with an association element 44 to a second side 39 of the second frame 38. The association element 44 can be seen in the view of Figure 1.

In particular, the longitudinal support 43 is adapted to slide in a guide provided on one of the first sides 36, the other one of these first sides 36 having an opening 46, substantially a recess on its annular structure, in which the take-up guide 17 can oscillate. The means for arresting the oscillation 41 are defined by the flanks of the opening 46, beyond which the take-up guide 17 cannot move when oscillating. In particular, on the flanks there are respective rubber pads 47 on which the association element 44 of the take-up guide 17 can come into abutment during oscillation.

In the second embodiment, the take-up guide 117 is also mounted on a support, installed cantilevered from the second side 39, and the first side 36, on the same flank of the second side 39 and close thereto, has an opening 46 in which the take-up guide 117 can oscillate. Also in the second embodiment the same means for arresting the oscillation 41, described above, are provided.

The oscillation is defined by the relative rotation of the second frame 38, which supports the take-up guide 17, 117 with respect to the first frame 35, and its amplitude is given by the variation in length of the portion of cable from the point of unwinding of the spool 13 up until the entry point thereof into an external pulley 51a.

The longitudinal support 43, and therefore the take-up guide 17, slides in a guide that centers the system, via a bearing 48.

The two take-up guides 17 in the example shown are installed in diametrically opposite positions and in the same way.

Each guide 16 is also installed on a longitudinal support, here indicated with 49, which is installed between the first sides 36 and with the interposition of respective bearings 50.

In the second embodiment of the apparatus 110, as shown in Figure 4, the take-up guide 117 is constituted by two elements mounted in succession on the support installed cantilevered from the second side 39, i.e. by a guide element 152 with its axis parallel to the rotation axis X and by a disk-shaped guide element 153, in series with said guide element, with its axis C perpendicular to the rotation axis X.

The guide element 152 substantially consists of a roller of short length and progressively narrows in transverse cross-section toward its central region so as toward define a circular groove guide for the wire or cable 14.

The disk-shaped guide element 153 also has guides for the wire or cable 14, in this case defined by lateral slits.

The roller 116 has, proximate to an end thereof, the end toward the pulleys, a pair of close circular grooves 154, which also act as a guide for the passage of the wire or cable 14. Here the groove closer to the first side 36 is defined as the "first groove", and the further groove is the "second groove".

The means for coordination comprise a system for detecting the displacement of the angular position of the first frame 35 with respect to the second frame 38 (by way of angular transduction with encoders/resolvers of the corresponding motors), thus determining the angular position of the take-up 17, 117 with respect to the cage 15. Such means are adapted to communicate with a system for controlling the rotation speed and the angular position of the first shaft 11.

The apparatus 10, 110 according to the invention also comprises a series of disk-like guides 51a and 51b which are integral with the cage 15, of which at least one first disk-like guide 51a is mounted on one of the first tension members 37 with a first axis A which is inclined with respect to a direction perpendicular to the rotation axis X and at least one second disklike guide 51b with a second axis B which is perpendicular with respect to the direction of the rotation axis X.

In particular, there are two first disk-like guides 51a in the first embodiment, mounted in diametrically opposite positions on respective tension members 37 of the first frame 35, and one in the second embodiment, and there are three second disk-like guides 51b, with parallel axes B, on the outer flank of the first side 36, at the opposite end from the end where the pulleys are. The disk-like guides 51a and 51b make it possible to guide the cable 14 being unwound from the spool 13 to outside the apparatus 10, 110 toward a cable strander.

In the apparatus 10 a first disk-like guide 51a, two guides 16 and, between these, a take-up guide 17 are provided. This configuration is repeated with these elements in diametrically opposite positions on the frames, to be used as a function of the point of extraction of the cable 14 from the spool 13.

The operation of the apparatus according to the invention is the following.

A spool 13 is installed inside the apparatus 10 and the cable 14 is made to pass from the spool 13, in succession, around a take-up guide 17, on a nearby guide 16 (the one on one side of the take-up or the one on the other side, depending on the unwinding direction of the cable) and on a first disk-like guide 51a (the one nearest to the guide 16 on which the cable is passing). From there it is brought to two consecutive guides of the second disk-like guides 51b (the ones located on the same radius that is perpendicular to the axis X), as shown in Figure 1, thus exiting from the apparatus 10 in the direction of the rotation axis X. The remaining guide 51b acts as a counterweight. In this case the spool 13 has a clockwise direction of unwinding, looking at the apparatus 10 from the side of the second guides 51b.

For anticlockwise unwinding (the unwinding direction depends on the direction of installation of the spool), the support carrying the guides is inverted 180°, with the cable passing on the guides mirror-symmetrically with respect to what is shown in Figure 1 and obtaining the opposite direction of detwisting with respect to the previous situation.

With the apparatus 110 the cable 14 is made to pass from the spool 13, in succession, on the guide 116, around the disk-shaped guide element 153 of the take-up guide 117, around the second circular groove 154, in order to return to the take-up guide 117 where it turns around the guide element 152 in order to return to the guide 116, on the first circular groove 154, and finally to the first disk-like guide 51a, from which it proceeds toward the second disk-like guides 51b, as described for the apparatus 10. The illustration shows the passage of the cable in the case of clockwise rotation of the spool. In this case too, the apparatus can be made to rotate in the other direction of rotation, therefore using the take-up guide 117 in the diametrically opposite position to the previous position, the roller 116 on the other side of this second take-up guide, and the first disk-like guide 51a mounted with the same inclination of the axis A as the previous inclination with respect to the axis C of the disk-shaped guide element 153 of this takeup guide 117. When the apparatus 10, 110 is activated, the motors activate the rotation of the spool 13, of the first frame 35 which supports the guides 16, 116, and of the second frame 38 which supports the take-up guide 17, 117.

The rotation speed of the second frame 38 which supports the take-up is set at a slightly greater level than the rotation speed of the first frame 35. The torque of the third motors applied to the third pulley 31 is modulated/limited in order to ensure, with the take-up guide 17, 117, a push to counteract the sag formed by the cable 14 between the exit point of the spool 13 and the entry point of the first guide 51a, so as to keep it under tension during its unwinding from the spool 13 in contrast with the direction of pull of the cable 14.

During the rotation and the unwinding of the cable 14, the angular position error of the take-up 17, 117 (the difference between its "zero position" and the position of the cage 15) is detected by the means for coordination and is communicated to the control system which as a consequence modifies the rotation speed of the spool 13 in order to cancel out the position error of the take-up 17, 117.

The zero position of the take-up 17, 117 is a configurable, preferably intermediate, position in the opening 46.

Every disturbance of the speed of the cable released by the spool 13 (owing to various phenomena such as: momentary variations of the diameter, tugging of the stranded cable, transients of acceleration and deceleration of the line, etc.) induces a positive or negative position error of the take-up 17, 117 which makes the control system react in order to decrease that error.

For example, a sudden decrease in the speed of the stranding line will result in a relaxing of the cable exiting from the spool 13 being unwound. The effect of the slowing of the cable 14 is substantially a displacement of the take-up guide 17, 117 which moves away from the guide 16, 116 on which the cable 14 is provided, in the direction of increase of the sag. The displacement is read by the angular position transducer, and the control system acts on the first motor to slow the rotation of the spool, so as to make the position of the take-up guide 17, 117 recover toward the "zero position" and return the sag to the original length.

Obviously the opposite occurs when the cable 13 undergoes an increase in the speed of unwinding from the spool 13.

The take-up guide 17, 117, although varying its position in such transients, still keeps the push toward the sag of the cable constant, and therefore keeps the tension of the cable constant.

Substantially the apparatus 10, 110 according to the invention is capable of detwisting the cable being unwound and adjusting its tension autonomously and moment by moment.

The apparatus 10, 110 according to the invention enables a precise control of the tension of the cable, with spools of small dimensions, of medium dimensions (above 400 mm in diameter) and of large dimensions (up to diameters of 800 mm), thus overcoming the speed limitations and therefore the productive limitations imposed by conventional apparatuses.

In practice it has been found that the invention fully achieves the intended aim and objects, by providing an apparatus that operates at a greater rotation speed than conventional machines, because it is able to contain, with constant and continuous control of the tension and of the rotation speed of the spool, the induced moments, and to limit and compensate for the deformations of the structure, independently of the weight and, as a consequence, of the inertias of the spools. A precise control and the containment of the induced moments makes it possible to limit the wear and tear of the mechanical elements.

It should also be noted that the concentricity of the shafts in rotation and of the frames supporting the guides makes it possible to obtain an apparatus that offers reduced space occupation.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements.

In practice the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.

The disclosures in Italian Patent Application No. 102021000002411 from which this application claims priority are incorporated herein by reference. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.