CH616018A5 - Process for manufacturing an insulated stranded wire conductor, wire conductor manufactured according to the process and installation for implementing the process - Google Patents

Abstract

The manufacturing line extends from left to right. The two pay-outs (1 and 2) each feed one of the alternate-lay cabling heads (5 and 6). The strands (3 and 4) formed in these cabling heads are pulled by tension-equalising haul-offs (7 and 8). Next, they pass into the multiple-extrusion head (10) fed with insulation material by the extruder (11). The working speed of the extruder is synchronised with that of the alternate-lay cabling. Next, the insulated wire conductor, comprising two flexible strands, passes through the cooling tank (14). It is pulled by the haul-offs (15) and wound up onto the reeler (16). Stranded conductors are thus made having the desired length. The strand arrives at the extrusion head immediately after leaving the head (5, 6). The lay (pitch) of the stranding is then fixed by the plastic, preventing risk of untwisting. <IMAGE>

Description

** ATTENTION ** start of the DESC field may contain end of CLMS **.

CLAIMS 1. A method of manufacturing an insulated flexible electrical conductor, comprising the stranding of a set of fine wires to form at least one strand and the sheathing of this strand in a coating of plastic material by extrusion, characterized in that the or the strands are formed by alternating wiring and then are led into an extruder whose working speed is synchronized with that of the alternating wiring, the production being carried out continuously, 2. Method according to claim 1, characterized in that several strands are formed simultaneously in different alternating wiring machines and are then led into the same extruder where they are coated with a sheath coating each of the strands separately.

3. Method according to claim 1, characterized in that the strand or strands are preheated between the stranding operation and engagement in the extruder.

4. Method according to claim 1, characterized in that the strand (s) are pulled through the alternating wiring machine (s) by one or two withdrawers arranged before entering the extruder.

5. Flexible insulated electrical conductor manufactured according to the method of claim 1, characterized in that it consists of at least one set of fine wires with alternating stranding wrapped in an insulating plastic sheath.

6. Installation for implementing the method according to claim 1, characterized in that it comprises a stranding line (1, 3, 5, 7, 9; 2, 4, 6, 8, 9) and an extruder (11) arranged in tandem, the stranding line comprising a reel (1, 2) and an alternating-wire stranding machine (5, 6) while the extruder comprises an extrusion head (10) traversed by the strand emerging from the stranding line.

7. Installation according to claim (6), characterized by a control device connected to the stranding line and to the extruder so as to adjust the working speed of these machines according to the speed of passage of the strand.

8. Installation according to claim 7, characterized in that it comprises at least one withdrawer (15) disposed at the outlet of a cooling tank (14) which follows the extruder (11), the speed of this withdrawer being adjusted by the control device.

9. Installation according to claim 8, characterized in that it comprises at least one withdrawer (7, 8) disposed at the outlet of the stranding machine to remove the tensions that can be created in the latter.

10. Installation according to claim 6, characterized in that it comprises several stranding lines (5, 6) each producing a strand and a multiple-head extruder (10) which sheaths the strands simultaneously.

The insulated flexible electrical conductors are generally formed of a strand, that is to say of a set of fine wires stranded with a determined pitch, coated with an insulating sheath generally made of plastic. Depending on the intended use for these conductors, they can include, for example, 7, 24 or 36 wires with a cross-section of 0.05 or 0.1 mm2. This produces conductors with an overall cross section of 0.5 to 2.5 mm2 intended for conventional electrical installations. In some cases, double conductors are used formed by two strands arranged parallel to each other and embedded in the same insulating sheath which keeps them separated from each other.

Up to now, it has not been possible to manufacture flexible insulated conductors continuously, because we encountered the following dilemma: a) The various stranding machines of the traditional type all require, either in the supplying part or in the receiving part, the use of coils carrying limited lengths of wire or strands.

b) Machines operating on the principle of alternating wiring allow continuous work, but alternating wiring of a set of bare thin wires, such as the strand of a flexible conductor, is not possible due to the lack of adequate means avoid untwisting under the effect of tensile forces.

However, alternating cabling is a process which is currently undergoing an accelerated development phase and which is applicable to the manufacture of many types of cables. It is used in particular to assemble insulated conductors to form quads or to make cables from rigid conductors. The conductors are linked, either by threads or textile ties, or by bonding insulating sheaths.

The object of the present invention is to allow the manufacture of continuously insulated flexible electrical conductors in order to obtain lengths of conductors in one piece as large as desired.

This process is based on the observation that it was possible to overcome the difficulty presented by the alternating wiring of the sets of wires forming flexible strands provided that the insulating sheath is extruded on the strand immediately after the latter has been formed. It has in fact been noted that if the strand reaches the extrusion head immediately after having left the alternating wiring head, the stranding pitch is fixed by the plastic material so that the risk of untwisting is eliminated.

To achieve the aim specified above, the subject of the present invention is: A method of manufacturing an insulated flexible electrical conductor, comprising the stranding of a set of fine wires to form at least one strand and the sheathing of this strand in a coating of plastic material by extrusion, characterized in that the one or more strands are formed by alternating wiring and then are led into an extruder whose working speed is synchronized with that of the alternating wiring, the production being carried out continuously; An insulated flexible electric conductor thus obtained, is characterized in that it consists of at least one set of fine wires with alternating stranding wrapped in an insulating plastic sheath; An installation for implementing the method, characterized in that it comprises a stranding line and an extrusion installation arranged in tandem, the stranding line comprising a reel and a stranding machine with alternating wiring while the installation d extrusion comprises an extruder, the head of which is crossed by the strand leaving the stranding line.

We will describe below, by way of example, a form of implementation of the method, as well as an example of embodiment of the installation which allows this implementation.

In the attached drawing: fig. 1 is a schematic top plan view showing the installation, object of the invention, and fig. 2 is a sectional view on a greatly enlarged scale showing the flexible electrical conductor with two strands, produced by the installation of FIG. 1.

In fig. 1, the production line extends from left to right from the reels which supply the unitary wires to the winder which collects the completed flexible conductor. We see at the left end of fig. 1, two groups of supply coils 1 and 2 which each have 24 coils distributed on the cob.

Each of the reels I and 2 therefore provides 24 fine wires for the manufacture of a strand. The two strands are represented by the numbers 3 and 4. They are formed, for the strand 3 in an alternating wiring head 5 and, for the strand 4 in a alternating wiring head 6. These wiring heads are of known construction in

oneself. Thus, the German DAS 1 515 730 describes wiring heads of this kind. A mobile assembly is rotatably mounted around an axis which coincides with the path followed by all of the wires coming from the reels. This mobile assembly comprises two groups of pulleys forming an accumulator on which a certain length of cable is wound.

The moving element is rotated so as to rotate around its axis. On either side of its ends are located fixed guide devices. It is known that if the direction of rotation of the moving element is reversed at fixed time intervals corresponding to the time necessary for a point of the wire to run through the entire length of the accumulator, the wires which enter the wiring head in being parallel to each other, undergoes through the entire wiring head a double twist whose direction alternates periodically. The wiring heads 5 and 6 are of this type. The strands 3 and 4 with alternating wiring, leaving the wiring heads 5 and 6, each pass over a withdrawer 7 or 8 which is driven so as to draw the wires from the reels through the wiring head. and 8 ensures a drive of the unitary wires which form each strand with a traction force as reduced as possible. These retractors could be combined in a single device.

As seen in the drawing, the reels 1 and 2 as well as the wiring heads 5 and 6 and the withdrawers 7 and 8 form two stranding lines arranged parallel to each other and which each ensure the formation of a strands 3 and 4. These strands 3 and 4 are guided by fixed pulleys 9 at the outlet of the withdrawers 7 and 8 and led into an extrusion head 10 which is fixed to the end of a screw extruder designated by generally by 11 and driven by a motor 12. The extrusion tool is shaped so as to direct the plastic that the cylinder of the extruder 11 pushes into the inlet of the extrusion head around the two strands 3 and 4 so as to form a double insulating sheath which coats the strands 3 and 4 as seen in FIG. 2.

It thus leaves the extrusion head 10 an insulated flexible electrical conductor 13 which enters a cooling tank 14, which is driven by a withdrawer 15 and which is wound on a winder 16. This winder, as well as the coils 1 and 2 are fixed installations, so that the coils can be as large as desired. It is therefore possible to manufacture with the line described succinctly above insulated flexible electrical conductors having the desired length. Due to the tandem arrangement of the installation described with the stranding lines 5 and 6 located in front of the extruder 11, it is necessary to provide a control device which is not shown in the drawing, but which ensures synchronism of the work of the extruder with that of the wiring heads 5 and 6. This control device will therefore act on the motors for rotating the wiring heads 5 and 6, as well as on the withdrawers 7 and 8 and on the withdrawer 15. The speeds of passage of the various wires and strands in the wiring head and in the extrusion head should be constant in order to avoid any exaggerated tensile force on the wire or on the strands during manufacture. . At the same time, the control device will govern the operating parameters of the extruder 11, in particular the speed of rotation of the screw which is driven by the motor 12 and, if necessary, the temperature at the outlet of the cylinder of the extruder.

Tests have shown that the flexible conductor produced in an installation of the kind which has just been described, meets the requirements for use and in particular that the extrusion of a molten plastic material on a flexible strand formed by wiring. alternating, caused sufficient adhesion between the plastic sheath and the strands of the strands for the alternating stranding of the strand to be fixed by this sheath. The flexible conductor therefore does not undergo untwisting and can be used to make permanent or transient connections without risk of disintegration. There is therefore no need to provide a bonding of the fine wires which constitute the strand, nor a attachment of these threads by means of a place such as a textile thread or a strip as has been provided in some cases, and in particular ment in the publication mentioned above (DAS 1,515,730).

Flexible conductors made of any number of wires can be manufactured by the method described, the strands of 7, 19, 24 or 36 wires being however the most frequent. These wires will have a section of 0.05 to 0.1 mm2 for example, the overall section of the conductor preferably being between 0.5 and 2.5 mm2. Of course, instead of providing a double stranding line, it is also possible to provide only one in the case of the manufacture of flexible electrical conductors with a single strand. As regards the insulation material produced by the extruder 11 and discharged by the head 10 onto the strand or strands, the materials usually used for insulating the conductors can be used without restriction.

In the case where the stranding line has only one single wiring head, and where, therefore, the extrusion head is crossed only by a strand, we could, if necessary, remove the withdrawer provided in the embodiment of fig. 1 between the stranding line and the extruder. The removal of this device simplifies the construction of the line and also simplifies the order problem since it's then the withdrawer 15 which determines the speed of passage of the wires and the strand throughout the installation. However, in this case, the strand is then subjected to a greater tensile force than in the case where an intermediate withdrawer has been provided, so that, in certain cases, it will remain essential to provide these intermediate withdrawers.

As a variant, one could also provide a preheating station for the strand (s) which would be arranged immediately before entering the extrusion head 10. Tests have shown that preheating of the metal before it passes through the head extrusion improved the adhesion of the insulating sheath on the metal of the conductors. This preheating also allows dyeing speeds of passage of the wire and the strands which are higher than what is obtained without preheating.

Of course, instead of the alternating wiring heads 5 and 6, we could also provide wiring devices alternated different. We know, in particular that it is possible to produce linear accumulators in alternating wiring heads comprising a tube driven in rotation in the same direction as the cable or the strand, that is to say periodically changing its direction of rotation and at the two ends of this tube cranks which transmit the rotational movement to the strand that we print on the wiring head.

The means provided for abruptly stopping the rotation of the wiring head and accelerating it to drive it in the other direction are not shown in the drawing and are not described here either. These are means known per se and which, advantageously, will bring the mobile assembly to its preferential speed of rotation in as little time as possible, therefore will be able to subject the wiring head to as large a rotary acceleration as possible. .

The tests for manufacturing insulated electrical conductors by the process described above have shown that this process allowed to obtain results superior to those to which one could expect. Until now, alternating wiring had only been practiced with elements already insulated beforehand, so that it was enough to slightly heat the sheaths to achieve their bonding during stranding which avoided the risk of untwisting. Other machines included elements which made it possible to tie the cables by means of a textile thread. However, neither of these two means would have been possible to allow the production of strands formed from a multitude of fine wires. On the other hand, it has been found that with an alternating wiring head of the kind described above, it was possible to achieve wire passage speeds of up to about 150 m / min. The length between the reversal points could reach 25 to 30 and even 35 meters, the pitch of the twisting being of the order of 20 to 30 mm.

Claims (10)

1. A method of manufacturing an insulated flexible electrical conductor, comprising the stranding of a set of fine wires to form at least one strand and the sheathing of this strand in a coating of plastic material by extrusion, characterized in that the or the strands are formed by alternating wiring and then are led into an extruder whose working speed is synchronized with that of the alternating wiring, the production being carried out continuously, 2. Method according to claim 1, characterized in that several strands are formed simultaneously in different alternating wiring machines and are then led into the same extruder where they are coated with a sheath coating each of the strands separately. 3. Method according to claim 1, characterized in that the strand or strands are preheated between the stranding operation and engagement in the extruder. 4. Method according to claim 1, characterized in that the strand (s) are pulled through the alternating wiring machine (s) by one or two withdrawers arranged before entering the extruder. 5. Flexible insulated electrical conductor manufactured according to the method of claim 1, characterized in that it consists of at least one set of fine wires with alternating stranding wrapped in an insulating plastic sheath. 6. Installation for implementing the method according to claim 1, characterized in that it comprises a stranding line (1, 3, 5, 7, 9; 2, 4, 6, 8, 9) and an extruder (11) arranged in tandem, the stranding line comprising a reel (1, 2) and an alternating-wire stranding machine (5, 6) while the extruder comprises an extrusion head (10) traversed by the strand emerging from the stranding line. 7. Installation according to claim (6), characterized by a control device connected to the stranding line and to the extruder so as to adjust the working speed of these machines according to the speed of passage of the strand. 8. Installation according to claim 7, characterized in that it comprises at least one withdrawer (15) disposed at the outlet of a cooling tank (14) which follows the extruder (11), the speed of this withdrawer being adjusted by the control device. 9. Installation according to claim 8, characterized in that it comprises at least one withdrawer (7, 8) disposed at the outlet of the stranding machine to remove the tensions that can be created in the latter. 10. Installation according to claim 6, characterized in that it comprises several stranding lines (5, 6) each producing a strand and a multiple-head extruder (10) which sheaths the strands simultaneously. The insulated flexible electrical conductors are generally formed of a strand, that is to say of a set of fine wires stranded with a determined pitch, coated with an insulating sheath generally made of plastic. Depending on the intended use for these conductors, they can include, for example, 7, 24 or 36 wires with a cross-section of 0.05 or 0.1 mm2. This produces conductors with an overall cross section of 0.5 to 2.5 mm2 intended for conventional electrical installations. In some cases, double conductors are used formed by two strands arranged parallel to each other and embedded in the same insulating sheath which keeps them separated from each other. Up to now, it has not been possible to manufacture flexible insulated conductors continuously, because we encountered the following dilemma: a) The various stranding machines of the traditional type all require, either in the supplying part or in the receiving part, the use of coils carrying limited lengths of wire or strands. b) Machines operating on the principle of alternating wiring allow continuous work, but alternating wiring of a set of bare thin wires, such as the strand of a flexible conductor, is not possible due to the lack of adequate means avoid untwisting under the effect of tensile forces. However, alternating cabling is a process which is currently undergoing an accelerated development phase and which is applicable to the manufacture of many types of cables. It is used in particular to assemble insulated conductors to form quads or to make cables from rigid conductors. The conductors are linked, either by threads or textile ties, or by bonding insulating sheaths. The object of the present invention is to allow the manufacture of continuously insulated flexible electrical conductors in order to obtain lengths of conductors in one piece as large as desired. This process is based on the observation that it was possible to overcome the difficulty presented by the alternating wiring of the sets of wires forming flexible strands provided that the insulating sheath is extruded on the strand immediately after the latter has been formed. It has in fact been noted that if the strand reaches the extrusion head immediately after having left the alternating wiring head, the stranding pitch is fixed by the plastic material so that the risk of untwisting is eliminated. To achieve the aim specified above, the subject of the present invention is: A method of manufacturing an insulated flexible electrical conductor, comprising the stranding of a set of fine wires to form at least one strand and the sheathing of this strand in a coating of plastic material by extrusion, characterized in that the one or more strands are formed by alternating wiring and then are led into an extruder whose working speed is synchronized with that of the alternating wiring, the production being carried out continuously; An insulated flexible electric conductor thus obtained, is characterized in that it consists of at least one set of fine wires with alternating stranding wrapped in an insulating plastic sheath; An installation for implementing the method, characterized in that it comprises a stranding line and an extrusion installation arranged in tandem, the stranding line comprising a reel and a stranding machine with alternating wiring while the installation d extrusion comprises an extruder, the head of which is crossed by the strand leaving the stranding line. We will describe below, by way of example, a form of implementation of the method, as well as an example of embodiment of the installation which allows this implementation. In the attached drawing: fig. 1 is a schematic top plan view showing the installation, object of the invention, and fig. 2 is a sectional view on a greatly enlarged scale showing the flexible electrical conductor with two strands, produced by the installation of FIG. 1. In fig. 1, the production line extends from left to right from the reels which supply the unitary wires to the winder which collects the completed flexible conductor. We see at the left end of fig. 1, two groups of supply coils 1 and 2 which each have 24 coils distributed on the cob. Each of the reels I and 2 therefore provides 24 fine wires for the manufacture of a strand. The two strands are represented by the numbers 3 and 4. They are formed, for the strand 3 in an alternating wiring head 5 and, for the strand 4 in a alternating wiring head 6. These wiring heads are of known construction in ** ATTENTION ** end of the CLMS field may contain start of DESC **.