EP0272211A2 - Electrical cable, manufacturing method of this cable and installation to use the method - Google Patents

Abstract

The cable consists of a series of pairs stranded alternately in one direction and in the other. At the locations of the reversal of the direction of stranding, the individual conductors are held in the form of a sheet and welded together side by side. Between two linked segments the neighboring pairs are twisted in opposite directions. The drain wire (FD) is provided with sheath segments (39) which are placed in the linked segments. These are marked by the deposition of a radioactive product or another detectable product during a subsequent manufacturing phase and actuating the marking (38). Once the general stranding and sheathing have been carried out or during these phases, the linked segments are identified by means of the product (38) and marked visibly.

Description

Electric cables are usually formed from a set of insulated wires stranded so as to form a bundle covered with a sheath. The general section of the cable is circular. In some cases, the cable comprises a central core of fibrous material around which the insulated wires are stranded. The set of wires can also be formed of several strands, for example of pairs or of quads, which are subjected before the sheathing to a general stranding operation. In the case where the cable has a non-metallic core, it is more flexible and also has greater resistance to tensile forces than is the case with cables whose section is entirely occupied by wires.

Also known, especially in the field of device and machine control, flat cables in which the insulated wires are arranged in layers and are connected to each other in parallel. In general, bare wires are embedded in a general sheath in the form of a ribbon which keeps the wires parallel to each other. The great advantage of this form of cable is that it is easy to find the two ends of the same wire in a segment of cable whose two ends must be connected, for example between a control device and a machine controlled by the device. In the ribbon which forms the flat cable, the various wires are in fact placed in a predetermined order. However, flat cables have several drawbacks: they are bulky, often it is difficult to install them inside a machine frame, in an angle or along an interior edge between two sections of walls. In addition, the manufacture of shielded flat cables presents great difficulties. Finally, the cost price of currently known flat cables is higher than that of cables of the same characteristics, but whose conductors are grouped in bundles and surrounded by a cylindrical sheath.

The object of the present invention is to create a cable which can be cut into sections having lengths chosen at will, the structure of which is similar to that of a bundle cable, but which has the same advantages as flat cables. The present invention also makes it possible to produce such a cable at an advantageous cost.

A first object of the invention is therefore an electric cable comprising a set of individual conductors each provided with an insulating sheath and a general coating, characterized in that it is formed of successive segments alternately grouped and linked, ie d. in which the conductors respectively have a bundle arrangement and a sheet arrangement of parallel elements, their sheaths then being linked to each other in a predetermined order over the entire length of these segments, so as to allow the IDC connection.

The present invention also relates to a method of manufacturing this cable, characterized in that the individual conductors are unwound into a sheet of parallel elements, these individual conductors are stranded alternately in groups each comprising a small number of conductors, each reversal of the direction of stranding the conductors are replaced in a layered arrangement of parallel elements and the sheaths of the conductors the ply are then linked side by side so as to firstly fix the stranding of the grouped segments and secondly to constitute the linked segments.

Finally, another object of the invention is an installation for implementing the method, characterized in that it comprises in a production line a reel for a sheet of insulated conductors, a group of two stranding blocks provided with '' a series of stranding devices with parallel axes, a tying station provided with several guiding and gripping devices, and a general stranding device located downstream of the tying station.

• la fig. l est une vue schématique en élévation montrant les postes principaux d'une partie d'une installation pour la fabrication du câble,
• la fig. 2 est une vue en perspective simpli­fiée schématique et partielle montrant l'installation,
• la fig. 3 est une vue en élévation frontale du bloc de toronnage amont monté sur le distributeur du dévidoir des conducteurs individuels,
• la fig. 4 est une vue en élévation frontale du bloc de toronnage aval monté sur le chariot,
• la fig. 5 est une vue en élévation latérale du bloc aval partiellement coupée selon la ligne V-V de la fig. 4,
• les fig. 6 A-E est une vue schématique montrant différentes étapes du procédé,
• la fig. 7 est une vue en perspective à échelle agrandie montrant un segment du câble après l'opération de soudage, ,
• la fig. 8 est une vue en plan à échelle agran­die d'un détail de l'installation de la fig. 1 montrant la préparation du conducteur de drain,
• la fig. 9 est une vue schématique en perspec­tive montrant un moyen d'allongement de la longueur du drain,
• la fig. 10 a -c est une vue schématique en coupe illustrant les différentes étapes de fabrication du câble,
• les fig. 11 a - b sont des coupes de segments groupés liés, et
• la fig. 12 est une vue en perspective d'un segment de câble obtenu selon le procédé de l'in­vention.

An example will be shown below of how the invention can be implemented and embodied on the basis of the appended drawings, of which:

• fig. l is a schematic elevational view showing the main stations of part of an installation for manufacturing the cable,
• fig. 2 is a simplified schematic and partial perspective view showing the installation,
• fig. 3 is a front elevation view of the upstream stranding block mounted on the distributor of the reel of the individual conductors,
• fig. 4 is a front elevation view of the downstream stranding block mounted on the carriage,
• fig. 5 is a side elevation view of the downstream block partially cut along the line VV of FIG. 4,
• fig. 6 AE is a schematic view showing different stages of the process,
• fig. 7 is an enlarged perspective view showing a segment of the cable after the welding operation,
• fig. 8 is a plan view on an enlarged scale of a detail of the installation of FIG. 1 showing the preparation of the drain conductor,
• fig. 9 is a schematic perspective view showing a means of lengthening the length of the drain,
• fig. 10 a -c is a schematic sectional view illustrating the various stages of manufacturing the cable,
• fig. 11 a - b are sections of linked grouped segments, and
• fig. 12 is a perspective view of a cable segment obtained according to the method of the invention.

The installation which will be described makes it possible to manufacture a cable according to the invention and more particularly a cable which is formed of a succession of grouped segments and of linked segments, the whole being surrounded by a continuous plastic casing which forms the general sheath of the cable and which is of cylindrical section. Along the grouped segments the individual conductors which form the cable are stranded, while in the linked segments, the sheaths of these conductors are linked to each other in a sheet of parallel conductors placed in a predetermined order, so that it It is easy to locate inside the sheet a predetermined conductor which one seeks to connect to particular devices. Thus, this arrangement meets the requirements of the connection called IDC (Insulation Displacement Connection). These areas where the conductors are linked in layers, can be identified in the cable terminated by the fact that the general sheath of the cable is marked at these locations. So it's easy cut the cable where the conductors are connected. After having stripped the cut end, the linked area which is normally folded back on itself inside the sheath can be developed in a flat sheet as seen in fig. 12.

Before proceeding to the description of the installation, it will also be indicated that along the grouped segments, the stranding of the individual conductors can be carried out in different ways. In the embodiment which will be described, the conductors are first of all stranded in pairs, and this according to the method of alternating stranding, i.e. that the direction of rotation of the conductors is reversed from one grouped segment to the next. In addition, in the sheet of conductors, the successive pairs are stranded in alternating directions. Finally, all of the pairs are themselves stranded before the sheathing is carried out. However, the arrangement in pairs is not compulsory. The individual conductors can also be introduced separately into the general sheath. One can also provide instead of pairs, quads or other groups of conductors. The conductors themselves are for example copper or aluminum wires or strands with a diameter of the order of 1 mm or less, coated with a sheath, preferably made of plastic.

Fig. 1 schematically shows on a small scale all the devices which carry out the main stages of cable manufacturing without the final sheathing or marking. The individual conductors exit from a group of reels 1 which are located at the left end in FIG. l and which include the number of coils desired each carrying an insulated conductor. These are unwound into a tablecloth parallel. The first device that the individual conductors encounter is the upstream multiple pairing machine 2 which is driven by a motor 3 with reversible direction of rotation and in synchronism with the downstream pairing machine. The conductors then meet the downstream multiple pairing machine 4 which is driven by a motor 5 with reversible direction of rotation. By treating the individual conductors in pairs, the pairing machine 4 forms a series of pairs, for example 8 or 10 pairs, or more depending on the applications.

The multiple pairing machine 4 is installed on a mobile carriage 6 carried by slides 7 on two pairs of parallel guide bars 8 having a length greater than that which the segments grouped in the completed cable will have. The upstream stranding block 2 cooperates with the block 4. It is fixed at the outlet of the reels 1 of the individual conductors. These are grouped in pairs corresponding to the pairs of the downstream block. The block 2 performs a synchronized stranding and in the opposite direction of the downstream block 4, allowing the latter to move while maintaining a sheet of conductors parallel to the outlet of the reel. At the right end of the path traveled by the device 6, is located a marking device 26 which, as will be seen below, deposits on the linked segments a marking product allowing after the sheathing of the cable to detect the location of the linked segments. The device located downstream of the device 6 is a withdrawer provided with an accumulator 9, for example with a puppet. The sheet of individual conductors is pulled downstream by the mobile device 6 intermittently so that the accumulator 9 acts as a regulator for the continuous supply of the devices located downstream. The installation located downstream of the accumulator 9 is a general stranding machine 10 capable of stranding all of the individual conductors including in the zones where they form linked segments and are therefore welded to each other.

The stranding machine 10 is associated with a die, and two covering devices which surround the cable with a textile wire envelope. These devices are conventional, so there is no need to describe them. They represent here an example among others. The coil 11 on which the cable is wound up will be taken up in a subsequent operation for the general sheathing of the cable, after which the external marking operation will follow, controlled by a detector capable of locating the location of the linked segments, provided with a detection product.

In the event that cable shielding is to be provided, this operation may take place, either after wrapping, or during the recovery operation, before sheathing.

Fig. 1 makes it possible to understand the principle of the process and the general construction of the means provided for the implementation.

The mobile device 6 moves back and forth over a distance which corresponds to the length of the segments on which the individual conductors are stranded in pairs, forming parallel strands separated from each other. These segments will hereinafter be called "grouped segments". Each intermediate segment between two successive grouped segments constitutes what is called a "linked segment", in which the individual conductors are arranged in a flat sheet of parallel conductors, the sheaths of which are linked to each other. The duct connection operation is carried out in a binding station 12 which includes guiding and holding means and welding means. As seen in fig. 1, the mobile device 6 comprises at its front or downstream end a clamp 13 and at its rear or upstream end the downstream stranding block 4. By means of a reversible direction of rotation motor 14 and a drive screw 15 it is moved alternately forwards and backwards. During the advance movement, the clamp 13 is clamped on the ply so that the latter is driven and is introduced into the accumulator 9. At the end of this movement, a fixed clamp 16 is clamped on the ply and the clamp 13 is open. The device 6 then moves back in several stages, as will be seen below so that firstly, the horizontal sheet which forms a linked segment is placed properly in the welding station 12 and that secondly, once the welding has been carried out, the paireuse 4 comes into action and strands the pairs backwards.

In fig. 2, we see represented schematically, various elements which are part of the stationary devices of the line. At the left end of this figure we see a certain number of insulated metal conductors, in particular copper wires or strands with a diameter of the order of 1 mm for example. This sheet N of copper wires or strands can include any number of conductors, but in the example described (see FIG. 3) a sheet formed of 11 pairs or in other words of 22 wires will be considered, to which the drain is added. Downstream we see a first pair of guide rails 8 which are interrupted to make room for the binding device designated as a whole by 12, then downstream of this device we again see a pair of guide rails 8 which support the downstream end of the mobile device 6. We also see in FIG. 2 the screw 15 for driving the mobile device, the drive reduction motor for this screw designated by 14, the stationary clamp 16, the two plates of which are vertically movable and controlled by jacks. The binding device 12 comprises downstream two opposing plates 17. Each of these plates is supported by a jack rod 18 and controlled by a cylinder 19. The plates 17 move vertically upwards and downwards. The lower plate 17 is provided with a series of parallel grooves 20 having a diameter which corresponds to the diameter of the insulation of the wires of the sheet N, so that, during the welding operation, each of these wires is engaged in one of the grooves 20. As will be indicated below, the upper plate of the binding station comprises a series of heating rods which are engaged in its thickness so that, when the two plates are pressed against each other other, the insulating sheaths of the wire segments pressed between the plates, are heated and bond by welding. (Fig. 10) The lower plate 17 may include a cooling circuit in order to accelerate the cooling of the weld after the connection has been made. In front and behind the lower welding plate 17 are arranged two parallel combs 21, the teeth of which are formed by narrow metal strips. These two combs are also mounted on cylinder rods and can be controlled vertically so as to raise or lower during the operation of the device, as will be seen below. Downstream and upstream of the combs are arranged two clamps 22 each comprising a lower crossbar and a crossbar upper, these two bars also being controlled by means of a linkage not shown, so as to raise and lower and pinch the web between them. On the downstream side, the clamp 22 is also associated with an intermediate device 23 which comprises a transverse blade 24 mounted on the rod of a jack 25. The role of this intermediate blade will appear below.

The two elements of the clamp 22 upstream each carry a knife 27 intended to cut the insulation of the upstream drain. These knives act during the welding operation and cut the insulation to the length provided for the insulated drain segment associated with the linked segments.

In fig. 2 we finally finally see the internal marking device. This device designated by 26 is placed immediately downstream of the clamp 16. It comprises a fixed base placed immediately under the sheet N and above this base a conduit supplied from a reservoir with a control valve, so that, in due time, a drop of the liquid contained in the reservoir can be poured onto the sheet at the location of this device 26. It is a liquid in which a short-lived radioactive product is dissolved. A device 28 with hot air jet makes it possible to accelerate the deposition of the radioactive compound. As a variant, it is also possible to choose a dye or any other product capable of causing an emission which, after the formation of the cable, crosses its sheath so as to allow detection of the place which has thus been marked internally during manufacture. of the cable.

Figs. 4 and 5 show in more detail the parts of the mobile device 6 which constitute the multiple pairing machine. These figures show the rails 8, the slides 7, the downstream stranding block 4 and the drive motor 5. The stranding block 4 is cantilevered downstream over a relatively large distance from the base 29 to which the slides 7 are fixed, the reduction gear 30 and the motor frame 5. The longitudinal bars 31 connect on either side of the base device 29 carrying the block 4 to the support base of the clamp 13. This ci is located downstream of the device 12. The block 4 is placed at the downstream end of a plate 32 which extends in overhang from the base 29 so as to be able to engage in the tying device 12 when the carriage is moved to its downstream position as will be seen later. The construction of the pairer block 4 is visible in FIGS. 4 and 5. This block is a rigid frame which contains the desired number, here 11, of rotating heads 33 each comprising an axis segment with two parallel longitudinal holes 34 and in the central part of the head, a drive toothing . The rotating heads 33 are supported in the frame 4 so as to rotate around parallel axes arranged in two rows at different levels. The toothed discs of the rotating heads are mutually engaged two of them and engaged with the elements of a gear train 35 of which one of the elements is connected by the shaft 36 to the output shaft of the reduction gear 30 driven by the motor 5. The construction is such that two adjacent rotating heads have different directions of rotation. The center distance of the axes projected on the horizontal plane corresponds to that of the grooves 20 of the binding plate 17. The motor 5 is connected to a device for control so as to be switched on and off alternately according to the different stages of the process, each stranding operation being carried out with an inversion of the direction of rotation of the motor.

It will also be noted in FIG. 4 the passage 37 which is used to guide a drain wire.

The operation of the line, and in particular of the devices 6 and 12 is illustrated in FIG. 6 which schematically shows the situation of the device at 5 stages of operation. Fig. 6 A shows the initial situation after the whole of the water table N has advanced one step. A linked segment of the cable is located opposite the internal marking device 26 and the upstream end of the preceding grouped segment is located between the jaws of the clamp 16. The mobile device 6 with in particular the frame of the pairing machine 4 is located in its extreme downstream position where it can be seen that the downstream face of the pairer 4 is located adjacent to the downstream gripper 22. The ply has been pulled into the position it occupies in this figure 6 I by the movement of the carriage 6 , the clamp 13 being clamped on the sheet. The ply of wires stranded in pairs is divided into two partial plies, the wires of one of these partial plies passing through the passages 34 of the stranding heads of the upper row, while the other conductors pass through the passages 34 of the heads. stranding the lower row. Thus between these two partial plies extends a space which corresponds to the difference in height between the axes of the two rows of stranding heads and this space is exactly at the level of the intermediate blade 24 which in the position shown is still retracted inside the cylinder of the cylinder 25. The first operation which takes place at this time consists in the closure of the clamp 16 as seen in FIG. 6 B and at the opening of the clamp 13. At the same time, the jack 23 of the intermediate blade 24 is controlled and the latter penetrates between the two partial plies of stranded wires. The motor 14 is started so that the screw 15 brings the carriage 6 upstream for a short distance, so that two partial plies of straight wires parallel to each other begin to form upstream of the clamp 22 which was closed immediately before the movement of the carriage 6 on the two partial plies of stranded son. As seen in fig. 6 B, the comb 21 located downstream is then released and can be moved so that the various insulated conductors leaving the passages 34 of the block 4 are separated from each other by the strips of the comb.

Fig. 6 C shows the subsequent step: the motor 14 is again started so that the carriage 6 moves upstream and this until the frame 29 is immediately upstream of the second clamp 22 which is located as mentioned above upstream of the binding device 12. Thus this binding device is completely free. The upstream clamp 22 is then closed so that there is between the two upstream and downstream clamps a single sheet segment in which all the conductors are rectilinear, parallel to each other, and equally spaced from each other. After closing the upstream clamp 22 the upstream comb 21 can also be moved upwards so as to regularize the spacing between the different conductors. At this time, the conductors are each located above one of the grooves 20 in the lower plate 17 of the welding device and also facing a shallower parallel groove formed in the underside of the upper welding plate.

It is at this time that the welding operation intended to form a linked segment can take place. As seen in fig. 6 D, the two plates of the binding device 12 are brought together on the sheet which is held between the two clamps 22 and this welding operation takes place so as to give the linked segment the appearance which will be seen later (v Fig. 7 and 10).

It is during the welding operation on the linked segment (n) that the device 26 deposits on the linked segment (n + 1) a drop of the internal marking product.

Once the welding operation has been carried out or even during this operation and while the welding is cooling, the motor 14 is again started so as to move the carriage 6 upstream, the clamp 16 always remaining closed. However, during this operation, the motor 5 is started, so that the stranding heads 33 rotate in the block 4 and form in the layer of conductors N eleven pairs distributed in two partial layers, the directions of twist of the different adjacent pairs being alternated. The displacement of the mobile device 6 thus continues until the desired length, this being determined by the fact that at the end of this displacement, the clamp 13 mounted on the downstream part of the carriage 6, which is open, is in the immediate vicinity of the downstream clamp 22.

At this time, the operations for forming a linked segment and the adjacent grouped segment are completed. The next step consists, as seen in fig. 6 E, to open the clamp 16 as well as the clamps 22 and to separate the two plates 17 from the device welding 12, lower the two combs 21 and close the clamp 13 on the ply N. The motor 5 is stopped, while the motor 14 after a stop to allow the opening of the devices mentioned above, is restarted in the direction which causes the carriage 6 to advance downstream. The entire sheet is then moved since it is driven by the clamp 13. Thus the linked segment which has just been formed in the binding device 12 moves over a distance corresponding to the sum of the lengths of a segment linked and a grouped segment. During these intermittent feed movements, the successive segments of the sheet are accumulated in the accumulator 9 which makes it possible to regulate the feed speed of the device 10 located downstream of the line.

As shown in fig. 1, this device 10 is a conventional stranding machine with a spool 11 which is mounted in a cage rotating around its longitudinal axis and driven by a motor M. A die is located upstream of the device and in this die, the pairs of stranded conductors as well as the layers of linked threads are stranded in a cylindrical bundle due to the rotation of the cage carrying the coil 11. Downstream of the die, two wrapping devices have been mounted which each unwind a textile thread intended to bind the beam and thus to keep its cylindrical section.

As mentioned above, the coils 11 once full are taken up in an extrusion line in which the cable receives its final sheathing, if necessary after having been provided with a metallic shield. After the extrusion operation, another station will be provided to detect the location of the linked segments thanks to the emission produced by the internal marking product. With regard to the marking operation which takes place on the segments linked to the downstream end of the travel of the carriage 6, it has been found that it was extremely simple to carry out this operation by running it through a nozzle (fig. 1) a drop of a solution containing a radioactive product. The solvent, which can be relatively volatile, evaporates quickly so that the drop of radioactive product forms on the linked segment a localization deposit 38. (fig. 7). After the sheathing operation, a current radioactive detector such as a Geiger or scintillation counter makes it easy to locate the locations of the linked segments and mark them. Other methods can be used to deposit a location detector on the linked segments. The use of a radioactive product, however, has the advantage that one can choose a product having a shelf life of the order of a few hours, so that any subsequent influence of this product is avoided.

It will also be noted that during the stranding operation carried out in the machine 10, the linked segments of the wire ply N fold back on themselves and take a configuration which is practically similar to that forming the grouped segments of the pairs. stranded.

Figs. 8 and 9 illustrate an alternative embodiment in which the cable is provided with a drain conductor designated by FD. In some cases, in fact, it is advantageous to have in the sheet of individual conductors, a drain conductor which is bare and which is in contact with the cable shield. This shielding can be achieved by a thin strip, for example of copper, which is wound on the strand in the manner of a covering or by a longitudinal envelope or by a wire mesh. In the case where it is wished to incorporate a drain conductor into the cable, the latter is provided with sheath segments 39 whose lengths correspond to the lengths of the linked segments or are possibly longer and which are placed in these segments as is see in fig. 7. In this case, this conductor is unwound as bare wire from a coil which is placed on the carriage 6. It is placed in the sheet of conductors passing through the pairing machine 4 after passing through an auxiliary device 40 (fig. 8). This figure shows the coil 41 from which the FD wire is unwound and an auxiliary coil 42 from which an empty sheath 43 takes place. The core of this sheath has a diameter such that the FD wire can slide with the inside of this sheath. The device 40 comprises as essential element a metal ring 44 which supports an entry guide element oriented radially and which ends in a conical piece 45 capable of guiding the wire FD in a radial direction relative to the ring 44. In an oblique direction relative to that of the guide piece 45 is disposed a also radial slide 47 which is open on its side facing the guide device 45 and which is adapted so as to guide the sheath 43. In addition the conical piece 45 carries on its side facing the slide 47 a blade 46 which we realize that it will split radially in its length the sheath 43 during the course of operations. The part 48 arranged radially but at right angles to the guide part 45, extends opposite the end of the slide 47 and it has the function of forcing the FD wire to penetrate through the slot of the sheath 43 which is kept open by the blade 46. The conductor thus sheathed passes through a guide tube 49 then in the passage 37 of the pairing machine 4. The control of the sequence of operations is carried out in such a way that sheath segments 39 are deposited on the wire FD at distances corresponding to the length of the grouped segments of the cable. Each time the knife 27 (fig. 2) has cut a sheath, the segment 39 located downstream of the knife is closed by the welding station 12. As can be seen in fig. 7, each segment 39 is placed along a linked segment of the cable and it is welded to the sheath of the neighboring conductor during the welding operation carried out by the device 12.

The device 50 of FIG. 8 allows by a brake action synchronized with the other functions to fix exactly the sheathed length of the drain wire. It is a pneumatically actuated device acting as a brake on the coil 42. It ensures the sliding of the bare drain inside the sheath 43 during the return movement of the carriage carrying the downstream stranding block 4 therefore during the phase where the downstream pairer is in operation. This device has two elements and acts simultaneously on the sheath 43 and on the coil 42 carrying the sheath.

Immediately downstream of the welding device 12, the device 51 of FIG. 9 gives the drain wire the necessary extra length and places it on the ply of the corresponding grouped segment in order to ensure, after the stranding, the contact with the shielding laid subsequently.

The different stages of the operations described above are summarized schematically in FIG. 10. In fig. 10a, the wires F are grouped in pairs and stranded along the length of the grouped segments, while on the length of the linked segments, they are held side by side in the form of a flat sheet (fig. 10b). The bare wire FD is provided with sheath segments 39 split, then welded. After the welding of the linked segments, the sheaths of the individual conductors are linked and form a coating mass having a section which corresponds to the shape of the grooves 20 in the plates 17.

After the stranding and the sheathing of the cable (fig. 10c), the pairs are brought together inside the sheath 52 (fig. 11). In fig. 11a, where the pairs are separated, the drain conductor FD is located at the periphery of the strand in contact with the shielding layer 53. On the other hand, as seen in FIG. 11b, on the linked segments, the ply of the individual conductors is folded back on itself so as to occupy a section similar to that of the different pairs and the conductor FD is here separated from the shield 53 by the thickness of the sheath 39. A Fig.11 shows sections of a grouped segment (a) and a linked segment (b) of a cable containing 36 conductors plus the drain conductor. Finally we see in fig. 12 the location of another linked segment which is marked by the markings 54. As can be seen, the location of a linked segment being marked on the sheath 52, it is easy to cut the cable in the middle of the marked segment and strip it over a segment of length slightly exceeding the length of the linked segment. This segment can then be spread out as seen in the lower part of FIG. 12 and all the conductors are in the form of a flat sheet and in the same order in each of these segments.

The method and the apparatus described above make it possible to produce a type of cable different from known cables and which has decisive advantages over them. Because individual drivers are stranded in pairs, the cable can be used in fields and for particular applications where it is necessary to avoid the risks of crosstalk and we know that in this case, the usual flat cables in which the conductors are parallel to each other others are not suitable. However, along the grouped segments, the stranding has the consequence that in many cases it is possible to do without a central core, the cable having, despite this absence, a circular cross section and sufficient support to be able to be put in place easily. From the manufacturing point of view, the alternating stranding of the different pairs in any case involves maintaining the individual conductors from distance to distance to allow the reversal of the stranding direction and this maintenance is combined with the formation of the linked segments in which the conductors are arranged in a sheet of conductors in a predetermined order. Finally, the manufacturing can be carried out continuously in a simple and rapid manner.

Claims (20)

1. Electric cable comprising a set of individual conductors each provided with an insulating sheath and a general coating, characterized in that it is formed of successive segments alternately grouped and linked, ie in which the conductors respectively have a bundle arrangement and a sheet arrangement of parallel elements, their sheaths then being linked to each other in a predetermined order over the entire length of these segments, so as to allow the IDC connection. 2. Cable according to claim 1, characterized in that it comprises a general coating of cylindrical shape and in that this coating comprises a marking making it possible to identify the linked segments. 3. Cable according to claim 1, characterized in that along the grouped segments the bundle is formed of strands each comprising a small number of individual conductors. 4. Cable according to claim 3, characterized in that the strands are pairs or fourths. 5. Cable according to claim 1, characterized in that it comprises a metal shielding casing and a drain conductor, the latter being bare along the grouped segments and embedded in a sheath along the linked segments, and this sheath being linked to the sheet of sheaths along one of the edges of the latter in each linked segment. 6. A method of manufacturing a cable according to claim l or according to one of claims 2 to 5, characterized in that the individual conductors are unwound in a sheet of parallel elements, these individual conductors are twisted alternately by groups each comprising a small number of conductors, at each reversal of the direction of stranding the conductors are replaced in a layered arrangement of parallel elements and the sheaths of the conductors of the lap are then linked side by side so as to fix the stranding of the grouped segments and on the other hand to constitute the linked segments. 7. Method according to claim 6, characterized in that a stranding of the conductors is then carried out and the general coating is deposited on the beam thus obtained. 8. Method according to claim 6, characterized in that the sheaths of the individual conductors are linked to one another in the segments linked by a welding operation without the addition of additional materials. 9. Method according to claim 6, characterized in that sections of sheaths spaced from each other by the length of the grouped segments are placed on a bare conductor and in that, during the binding operation, this conductor in a position located at the edge of the sheet, each sheath section being linked to the sheath of the neighboring element. 10. Method according to claims 7 and 9, characterized in that the overall stranding is carried out in such a way that along the grouped segments the bare conductor is located outside the bundle and in that the bundle is then coated a metal shielding envelope in contact with the bare conductor along the grouped segments. 11. Method according to claim 6, characterized in that, during each operation of forming a linked segment, a localization signal transmitter is placed on each linked segment and in that, after the deposition of the general coating the locations of the linked segments are detected by means of the signal emitted by the transmitter and these locations are marked in a visible manner. 12. The method of claim 11, characterized in that a short-lived radioactive product is used as the transmitter of a location signal. 13. Installation for the implementation of the method according to claim 6, characterized in that it comprises in a production line a reel for a sheet of insulated conductors, a group of two stranding blocks provided with a series of devices stranding with parallel axes, a binding station provided with several guiding and gripping devices, and an overall stranding device located downstream of the binding station. 14. Installation according to claim 13, characterized in that the binding station is located at a fixed location, and in that the downstream stranding block is mounted on a carriage moving alternately forward and backward relative at the tying station, the forward movement having the effect of advancing the ply of the individual conductors while the rearward displacement has the effect of forming strands of a group of cable segment, the ply then being fixed and the tying station in action. 15. Installation according to claim 13, characterized in that the guiding and clamping devices are arranged so as to clamp the individual conductors in two locations spaced at a distance at least equal to the length of the linked segments and to keep them under form of a sheet of parallel elements, located in the same plane. 16. Installation according to any one of claims 13 to 15, characterized in that it comprises an intermittent sheathing station which is associated with the downstream stranding block and which is capable of preparing and installing a bare conductor provided with segments of sheath and constituting a drain. 17. Installation according to claim 16, characterized in that the intermittent sheathing station comprises a fixed blade associated with means for guiding an empty sheath so that said sheath split in its length opens when it is moves axially, and means for continuously introducing a bare conductor into the empty sheath and kept in the open position. 18. Installation according to claim 17, characterized in that means for cutting the sheath along a plane perpendicular to its axis are associated with the welding station. 19. Installation according to claims 9 to 18, characterized by means for giving the length of drain associated with a grouped segment a value greater than the distance between two connected segments so as to maintain the drain at the periphery of the grouped segments. 20. Means according to claim 19, characterized in that it is attached to the welding device and that it comprises a part gripping the drain downstream of a segment and a part which fixes an excess length of bare drain to through the sheathing device of this drain and places it above the corresponding grouped conductor ply.

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