EP3172742B1 - Method for producing an electrical line, electrical line, and vehicle on-board power supply system having a corresponding electrical line - Google Patents

Description

The invention relates to a method for producing an electrical line with at least one wire, which has a wire bundle made up of a number of individual wires and an insulating sheathing surrounding the wire bundle. The invention also relates to such an electrical line and a vehicle electrical system with a corresponding electrical line.

Such a method and such an electrical line are for example from U.S. 4,471,161 refer to. It describes a stranded wire and its manufacture, in which a plurality of individual wires are twisted together to form a strand with the aid of a stranding machine. The stranded wire produced in this way is also surrounded by an extruded sheathing to form the core. Such cores with stranded conductors are used in particular for applications in which a high degree of flexibility of the line is desired. Due to the large number of individual wires in the stranded conductor, there is such flexibility compared, for example, to cores with a solid wire as the conductor.

Furthermore, for example, from the US4426837 B shows a stranding machine for the production of stranded individual wires with opposing lay (SZ stranding). Here, the individual wires are twisted together with an elongated tube within which they are routed. Due to the rotation of the tube, the individual wires are stranded together as they exit the tube and are then fed to an extruder for the application of a sheath.

In the production of stranded conductors, for example, it is from the DE 689 15 881 T2 , from the EP 1 191 545 A1 , from the JPS5622008 A , from the U.S. 2002/0050395 A1 or also from the US5449861B known in principle to compact the stranded conductors, i.e. to press the individual wires against one another. The individual wires are regularly twisted during the stranding or stranding process or else bundles of individual wires are first fed to a stranding element, for example a stranding nipple or a stranding disk. If compacting is desired, the stranding nipple is designed accordingly, for example, so that compacting takes place as a result. From the DE 689 15 881 T2 the use of a drawing die is known. In all cases, the wire bundle brought together in this way is fed to a stranding machine, at the end of which the stranded wire bundle is wound onto a take-up spool. The insulating covering is usually applied around the stranded wire bundle afterwards in a separate process step.

However, such a stranding or stranding process is very complex overall, which leads to higher costs compared to cores with a solid wire instead of a stranded conductor, for example. The production of a cable with compressed, untwisted individual wires is over US2002050395 A1 known.

If the stranded conductors are to be used in the automotive sector, for example as part of a motor vehicle on-board network, then the design of the stranded conductors is also typically adapted to specific standards, such as can be found in JIS C 3406-1987 or JASO D 611-94 . The stranded conductors in the automotive sector are typically designed for low voltages. As a rule, they should be as compact as possible and also light. With regard to the most compact configuration possible, it is known, for example from JASO D 611-94, to compact the stranded conductors in order to press the stranded assembly in particular into a circular shape. To reduce weight, lines with reduced, thin-walled insulation, so-called FLRY lines, are known. Stranded conductors for the automotive sector for low voltages and low currents typically have a stranding element made up of a large number of individual wires, usually 7-70, in particular 7-37, each of which has an individual wire diameter in the range from 0.18 to 0.32 mm, see above that the stranded conductor has a diameter in the range of about 0.8mm to 2mm.

Proceeding from this, the invention is based on the object of enabling a cost-effective production of a flexible line.

This object is achieved according to the invention by a method having the features of claim 1 and by a line having the features of claim 9. Preferred developments are contained in the dependent claims. The advantages and preferred configurations listed with regard to the method can also be transferred to the line and vice versa.

The method is used here to produce a cable with a wire bundle made up of a number of individual wires and with an insulating sheath. The sheathing is produced by means of an extruder, for which purpose the wire bundle made up of long individual wires is fed continuously to the extruder in a feed area. To specify the cross-sectional shape of the wire bundle, the wire bundle is guided through a shaping element in the feed area directly in front of the extruder along a central longitudinal axis, with the shaping element rotating about its central longitudinal axis and the wire bundle. Immediately following the shaping element, the insulating sheathing is applied to the wire bundle by means of the extruder. There is therefore a relative rotational movement of the shaping element around the bundle of wires. The desired cross-sectional shape of the wire bundle in the finished strand is set by the shaping element. For this purpose, the individual wires of the wire bundle, which are in particular loose, are brought together in the radial direction.

The wire bundle is thus quasi prepared immediately before the extruder in the feed area for treatment in the extruder, which, among other things, facilitates the application of the insulating sheathing to the wire bundle. This configuration is based on the basic idea of dispensing with the expensive stranding using a stranding machine and feeding the wire bundle to the extruder without being stranded, or at least without a targeted stranding. The shaping element thus only serves to bring the wire bundle into a desired, for example, circular shape. The wire bundle does not rotate with the rotating shaping element, nor does the individual wires twist relative to one another with the aid of the rotating shaping element. The wire bundle becomes in this shape impressed on the wire bundle by the shaping element then fed directly to the extruder, so that the insulation applied by the extrusion process keeps the wire bundle in the specified desired geometry. “Immediately following” is therefore understood to mean that the geometry predetermined by the shaping element is still retained and is fixed directly in an extrusion step that immediately follows both in terms of time and space.

It is of particular importance for the rotating shaping element that it rotates about its central longitudinal axis, ie usually about a direction in which the individual wires are fed. As a result, forces that act on the individual wires when the individual wires are passed through the shaping element are better distributed, since the shaping element rotates relative to the wire bundle. As a result, the stress on the individual wire is reduced and the risk of the wire tearing off while the individual wires are being guided through the shaping element is reduced.

As a result of this measure, no stranding is required overall. In this context, stranding is generally understood to mean any targeted twisting or twisting of the individual wires relative to one another about a central longitudinal axis after they have been unwound from a drum. This includes classic stranding, in which the individual wires are stranded in layers around a central core and thus have a symmetrical, concentric structure. In the present case, however, stranding is also understood in a broader sense as so-called twisting, in which the individual wires in the bundle are twisted about a central longitudinal axis, with this twisting not achieving a defined position of the individual wires, as is the case in the classic stranding process.

The line produced in this way is manufactured in a continuous process as a quasi endless product with a length of typically several hundred meters. After the sheathing has been applied, the cable is therefore typically also rolled up on a drum.

In a preferred development, such a targeted twisting or stranding and in particular a stranding machine is therefore complete omitted and the individual wires are in the wire bundle untwisted or at least largely untwisted. The individual wires therefore run parallel to one another to a good approximation. They are fed to the shaping element at least essentially and preferably exactly in parallel and are also carried on in parallel therein and leave the shaping element untwisted.

As an alternative to an exactly parallel alignment, a comparatively large lay length of more than 0.5 m and in particular of more than 2 m up to an infinite lay length of the individual wires running parallel is provided in an expedient embodiment. Here, the lay length describes the length in which the wire bundle rotates once through 360° around its own central longitudinal axis. A feed that is not exactly parallel of this kind results at most from the wire bundle being unwound from a, in particular, stationary drum. Here, too, there is no active (rotating) stranding or bunching element and therefore no conventional bunching machine.

In principle, the arrangement of the shaping unit directly in front of the extruder can also be used with stranded conductors. Of particular importance here is that the shaping element rotates around the bundle of wires, as a result of which the stress on the individual wires is kept low. In this case, therefore, an already stranded wire bundle is fed to the shaping element. This is in turn carried out by the rotating shaping element without it rotating with it. Here, too, a desired shape takes place, so that the finished line has good roundness and the subsequently applied sheathing has a high degree of concentricity with the wire bundle. The wire bundle is brought into the desired shape, in particular rounded, by the shaping element after the stranding process and, for example, after several deflections.

In terms of manufacturing technology, the individual wires in the non-stranded embodiment variant are usually unwound as a more or less loose bundle from a supply, in particular a drum, and fed to the shaping element. If necessary, several individual wires or bundles of individual wires are first brought together before the shaping element from several stocks and are combined in the shaping element to form a wire bundle.

If the bundle is not unwound from a rotating drum but from a stationary drum, this typically leads to a twisting, more precisely twisting, of the individual wires in the wire bundle that is caused by the unwinding process and is not deliberately caused, so that the individual wires - as stated above - are not exactly be fed in parallel. However, this results in a comparatively long lay length of at least more than 0.5 m and in particular at least more than 2 m. In contrast, in the case of twists created specifically for specific applications in the automotive sector, the lay length is in the range from a few millimeters to 0.1 m.

Overall, a cost-effective production method is achieved as a result of the omission of the complex stranding process. At the same time, the desired high flexibility of the line is maintained through the use of individual wires.

A particular advantage of the large to infinite lay length can also be seen in the material and weight savings due to the large or infinite lay length, which is of particular importance for the intended field of application in the automotive sector. Compared to conventional stranded conductors, savings of around 1% can be achieved through this alone.

It is particularly important here that the wire bundle is prepared with the aid of the shaping element directly in front of the extruder. Correspondingly, the shaping element in which the wire bundle is prepared is positioned preferably less than 2 m and in particular less than 0.5 m away from the extruder, ie quasi the extruder inlet.

According to an expedient variant of the method, the shaping element is also used to form the individual wires transversely to the longitudinal direction of the individual wires to apply to each other, thereby typically forming a wire bundle with approximately cylinder jacket-shaped surface. In this way, a wire bundle is created which has the smallest possible thickness or the smallest possible diameter. According to a first embodiment variant, the individual wires are not deformed here. The individual wires placed against one another in this way are immediately subsequently covered in the extruder with the insulating sheath, typically a plastic, so that the wire bundle is held by the sheath in its shape specified by the shaping element.

For this purpose, the shaping element is advantageously designed as a shaping sleeve, i.e. as a body that is at least partially in the shape of a hollow cylinder and/or a truncated cone, through which the wire bundle is guided in the feed area immediately in front of the extruder. According to the first embodiment variant, the dimensions of the shaping sleeve are selected in such a way that the individual wires in the wire bundle are deformed in their relative position to the longitudinal axis of the wire bundle, but are not deformed geometrically.

In a preferred second alternative, the shaping element not only results in a type of alignment or repositioning of the individual wires in the wire bundle, but also a compression of the wire bundle, in which the individual wires in the wire bundle are pressed together as they are pulled through the shaping element, in order to increase the thickness of the wire bundle or to further reduce the diameter of the wire bundle. The shaping element has a conical inlet area and tapers to a final diameter which is dimensioned in such a way that the desired compression takes place. Compression is understood here to mean a reduction in the diameter of the wire bundle of, for example, 1% to 3%, based on a diameter in the most compact possible arrangement of the individual wires without deformation of the individual wires themselves. The particular advantage of compression is that of better rounding , so that the surface of the wire bundle is further approximated to a cylinder surface. This creates the cladding material required for extrusion and for cladding kept low. Furthermore, the wire bundle is held together at least somewhat by the compression, so that the individual wires do not diverge on the way to the extruder.

As explained above, it is also provided that the shaping element rotates about the central longitudinal axis. In particular during the compression process, the individual wires lying on the outside are highly stressed in the longitudinal direction. Under certain circumstances, this can lead to the individual wires being torn off. Due to the rotation of the shaping element, the longitudinal forces that occur are now diverted laterally, as a result of which the stress on the individual wire is reduced. In order to achieve this, the rotation speed is preferably several 100 rpm and more preferably greater than 500 rpm. The shaping element is usually actively driven.

The risk of such a wire tearing off is also present in particular as a result of the usually very small cross sections of the individual wires. The individual wires, which usually consist of copper or a copper alloy, typically have a diameter of <1 mm, in particular also <0.5 mm.

For the application of interest here, i.e. in particular for an application in the automotive sector, comparatively small cables are produced, for example according to the standards mentioned at the beginning, in which the diameter of the entire wire bundle within the core is a maximum in the range of 2 mm to 4 mm lies. Correspondingly, therefore, only a limited number of individual wires, usually less than 60, preferably less than 20, individual wires is provided. The individual wires typically have a diameter in the range from 0.11 to 0.40 mm or even up to 0.60 mm.

A wire manufactured in this way has a comparable level of resistance to breakage as a classic stranded conductor in which the individual wires are twisted together. However, the manufacturing effort is lower than with a classic stranded conductor, which means that the production costs are also lower. Such a cable thus represents a kind of intermediate solution between a solid wire conductor and a classic stranded conductor, which is advantageous for various areas of application. Accordingly, by means of the method presented here, lines are preferably produced with at least one such core with a wire bundle made up of a number of individual wires that are not twisted. Such a core is used in particular for single-core lines but also for multi-core lines. In the case of multi-core cables, the individual cores are preferably combined by a common cable sheath. Alternatively, the individual cores are connected to one another, for example in the manner of a (raster) ribbon cable. Such single-core or multi-core cables are used in particular in the motor vehicle sector. The method described here with the direct arrangement of the shaping element immediately before the extrusion process is used in particular for non-stranded, ie untwisted, wire bundles. In principle, however, this method can also be used in the case of stranded wire bundles, ie stranded wire bundles and, in particular, also in the case of twisted wire bundles. In particular in the embodiment variant in which the wire bundle is compacted with the aid of the compacting unit, ie in particular the shaping sleeve.

Fig. 1

in einer Querschnittsdarstellung einer einadrigen Leitung,

Fig. 2

eine Längsschnittdarstellung A-A gemäß Fig.1,

Fig. 3

in einer Aufsicht eine Fertigungsanlage für die Leitung sowie

Fig. 4

in einer Längsschnittdarstellung eine alternative Ausführung einer einadrigen Leitung.

Exemplary embodiments of the invention are explained in more detail below using a schematic drawing. Show in it:

1

in a cross-sectional representation of a single-core cable,

2

a longitudinal section view AA according to Fig.1 ,

3

in a supervision a manufacturing plant for the line as well

4

in a longitudinal sectional view, an alternative embodiment of a single-core line.

Corresponding parts are provided with the same reference symbols in all figures.

An example described below and in 1 The single-core line 2 shown in a cross-sectional representation that is not true to scale is formed by a core 4.

This includes a wire bundle 6, which is covered by an insulating sheath 8 made of plastic. In the exemplary embodiment, each wire bundle 6 consists of seven individual wires 10 with a diameter d1<1 mm, with six individual wires 10 bearing against a central individual wire 10 on the peripheral side.

As in 1 the wire bundle 6 is indicated as a compressed wire bundle 6 and the individual wires 10 are pressed together accordingly. As a result, the thickness of each wire bundle 6 or the diameter of each wire bundle 6 is reduced and the cross-sectional shape of each individual wire 10 deviates from a round shape due to the deformation that each individual wire 10 undergoes in the course of compression of the wire bundles 6. The overall diameter d2 of the wire bundle 6 is in the range of 2 to 3 mm, for example.

As a result of this compression, the two wire bundles 6 are each held in their shape in part even without the insulating sheathing 8 . Because of the compression, the cohesion between the individual wires 10 is typically not as pronounced as in the case of a classic stranded conductor, in which the shape of the stranded wire is mainly due to the targeted twisting of the individual wires 10 . Such a targeted twisting is not given in the wire bundles 6, as this from 2 emerges schematically. The individual wires 10 therefore run at least essentially parallel to one another and to a central longitudinal axis. So they are untwisted.

A corresponding cable 2 is manufactured in a production plant 12, as shown in 3 is not drawn to scale. In this case, the prefabricated individual wires 10 are unwound from a wire drum 14, for example as a loose wire bundle 6, and fed continuously to an extruder 16, in which they are provided with the insulating sheathing 8. Directly in front of the extruder 16, ie in a feed area seen in the processing direction A in front of the extruder inlet, the individual wires 10 are connected by a Compression unit, namely a shaping sleeve 18, with the help of which the individual wires 10 are bundled and deformed into a compressed wire bundle 6. An outlet of the shaping sleeve 18 is spaced from an inlet of the extruder by a distance a. The distance a is preferably a maximum of a few meters, in particular less than 2 m, preferably around 0.5 m.

The processing speed, ie the speed at which the wire bundle 6 is drawn through the shaping sleeve 18, is typically 1000-2000 m/min.

In order to laterally dissipate the forces that occur during compression and thus reduce the risk of the wire tearing off, the shaping sleeve 18 rotates around the central longitudinal axis 20 of the wire bundle 6. It preferably rotates at a speed of more than 500 rpm, in particular around 1000 rpm. at least

The sheath 8 is then extruded onto the wire bundle in the extruder 16 .

Instead of the shaping sleeve 18 described here, in principle other compression units can also be used, such as those used for rotary swaging of bundles. In this case, several movable shaping jaws are distributed around the circumference of the wire bundle 6 and press the wire bundle 6 by means of coordinated movement sequences. However, this rotary swaging is usually used for significantly larger cross sections.

Furthermore, it should be pointed out that the individual wires 10 of the bundle 6 are hard as drawn and should not be soft-annealed. Studies have shown that only hard-drawn wires can be compressed to the desired extent. Namely, annealed wire material preferably flows only in the axial direction, without that the desired compression, ie deformation in the radial direction of the individual wires 10 takes place.

If the bundle 6 is not unwound from a rotating wire drum 14 during the manufacture of the cable 2, but rather from a stationary wire drum 14, this typically leads to a twisting of the individual wires 10 in the wire bundle 6, which is not intentionally caused, with a lay length s of, for example, 2 m, like this in 4 is sketched. Here, the lay length s denotes the length in which the wire bundle rotates once through 360° around its own central longitudinal axis. The length of lay s of the twisting or twisting caused by the unwinding process essentially depends on the diameter of the wire drum 14 and is significantly greater than a length of lay that is produced in a targeted manner according to the prior art.

The invention is not limited to the embodiment described above. On the contrary, other variants of the invention can also be derived from this by a person skilled in the art without departing from the subject matter of the invention. In particular, all of the individual features described in connection with the exemplary embodiment can also be combined with one another in other ways without departing from the subject matter of the invention.

Reference List

2

line/cable

4

Vein

6

wire bundles/bundles

8th

sheathing

10

single wire

12

production plant

14

wire drum

16

extruder

18

shaping sleeve

20

central longitudinal axis

A

processing direction

a

Distance

d1

Single wire diameter

d2

Wire bundle diameter

s

stroke length

Claims (12)

1. Method for producing an electrical line (2) having at least one conductor (4), which has a wire bundle (6) made of a number of individual wires (10) and an insulating sheath (8) surrounding the latter, wherein the wire bundle (6) is guided through a shaping element (18) along a central longitudinal axis (20) in a feed area immediately upstream of an extruder (16) in order to guide and to predefine its cross-sectional shape, wherein the shaping element (18) rotates about the central longitudinal axis (20), and in that the insulating sheath (8) is then applied to the wire bundle (6) by means of the extruder (16), characterized in that the shaping element (18) rotates relative to the wire bundle (6), and in that the individual wires (10) in the wire bundle (6) are untwisted or the wire bundle (6) has a lay length of a minimum of 0.5 m.
2. Method according to the preceding claim,
   characterized in that
   the wire bundle (6) has a lay length of a minimum of 2 m.
3. Method according to one of the preceding claims,
   characterized in that
   the shaping element (18) is positioned at a distance (a) of less than 2 m from the extruder (16).
4. Method according to one of the preceding claims,
   characterized in that
   the shaping element (18) is positioned at a distance (a) of less than 0.5 m from the extruder (16).
5. Method according to one of the preceding claims,
   characterized in that
   the shaping element (18) is formed as a shaping sleeve (18) .
6. Method according to one of the preceding claims,
   characterized in that
   the shaping element (18) is formed as a shaping sleeve (18), and in that the wire bundle (6) is compressed by means of the shaping sleeve (18).
7. Method according to the preceding claim,
   characterized in that
   the diameter of the wire bundle (6) is reduced by at least 3%.
8. Method according to one of the preceding claims,
   characterized in that
   the shaping element (18) rotates at a speed of at least 500 rev/min.
9. Electrical line (2) produced by means of a method according to Claim 6, having at least one conductor (4), which has a compressed wire bundle (6) made of a number of individual wires (10) and an insulating sheath (8) enveloping the wire bundle (6), wherein the individual wires (10) in the wire bundle (6) are untwisted or in that the wire bundle (6) has a lay length of a minimum of 0.5 m and preferably of a minimum of 2 m, and wherein the individual wires (10) are pressed with one another.
10. Line (2) according to Claim 9,
    characterized in that
    the individual wires (10) have a diameter (d1) of less than 1 mm.
11. Line (2) according to either of Claims 9 and 10,
    characterized in that
    the wire bundle (6) has an overall diameter (d2) of a maximum of 4 mm.
12. Line (2) according to one of Claims 9 to 11, which is used in a motor vehicle on-board power supply system.

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