KR20020096904A - Cable for transmitting electrical signals - Google Patents

Abstract

PURPOSE: A transmission cable for electrical signals is provided to remove easily an mantle and to reduce manufacturing costs. CONSTITUTION: A transmission cable for electrical signals comprises a cable core of at least two adjacent and insulated strands(1,2), an inner mantle(4) which can be removed easily from the strands, a screen and an outer mantle(8). The barrier material comprises a cladding(3) on the outer surface of each strand of insulation(1a,2a). The screen is composed of a metal foil(5) against the inner mantle, stranding layer formed of a plurality of metal wires, and a metal foil layer(7) disposed on the stranding layer.

Description

Electrical signal transmission cable {CABLE FOR TRANSMITTING ELECTRICAL SIGNALS}

The present invention relates to an electrical signal transmission cable according to a higher concept of claim 1 and a method of manufacturing said cable according to claim 14.

In order to mount a plug-type connector to the core of the electric cable, it is necessary to uncover the core. Here, it is common to fail to prevent damage to the cores lying inside when removing the cable sheath.

In order to remove the cable sheath it is known to use a radial cutting tool which cuts the cable sheath and, if necessary, the shield of the provided cable. The difficulty arises in that the inner covering existing under the protective layer is not easily removed because it is attached to the core wire.

An electrical signal transmission cable is known from German Patent No. 298 08 657, in which core wires placed next to each other are surrounded by a polyester foil. On the polyester foil is provided an inner coating of polyvinyl chloride which is easily extrudable. An interweaving protective layer is arranged in a ring shape around the inner coating, which is in turn surrounded by the outer coating.

Such known cables have some serious drawbacks. Polyester foils prevent the inner coating from forming gussets between the core wires.

This may in some cases lead to a change in the position of the core wires with respect to each other and consequently a change in transmission characteristics. In addition, the separating foil must be removed over time after removal of the inner coating.

Another disadvantage is that as the material for the inner coating, polyvinylchloride is used, which causes problems depending on the environment, as is well known.

However, a very important disadvantage is that the protective layer is formed through the network, and providing the network with cable technology is a time-consuming process, which increases the cost of producing the cable.

With respect to this prior art, the object of the present invention is to provide a cable which can be easily stripped and can be manufactured inexpensively and a method of manufacturing such a cable.

The problem is solved through the content of the features of claims 1 and 14.

In addition to the direct advantages of the above subject matter, the cable according to the teachings of the present invention exhibits very good transmission characteristics.

The invention is explained in more detail by the embodiment schematically shown in Figs.

1 is a cross-sectional view of a cable according to the present invention.

2 is a diagram showing a method of manufacturing a cable or conductor.

<Explanation of symbols for the main parts of the drawings>

1, 2: core wire

1a, 2a: conductor

1b, 2b: Insulation part

3: Separation layer

4: inner cloth

5, 7: metal foil

6: stranding layer

8: outer cloth

1 shows a cross-sectional view of a cable according to the invention. The cable comprises two cores 1, 2 stranded with each other. Each of the core wires 1 and 2 has conductors 1a and 2a such as, for example, a copper cord and insulating layers 1b and 2b.

Advantageously, the core insulations 1a, 2a comprise two layers, including an internal soft foamed layer and an external hard massive layer. Suitable materials for the layer are expandable solid polypropylene and expandable solid polyethylene.

The core surface is provided with a separation layer 3 comprising, for example, wax, paraffin or the like. The separating layer 3 serves to simplify the removal of the inner sheath 4. The inner sheath 4 comprises an extruded expandable, ductile expanded polyolefin, so that the inner sheath 4 can be easily removed through edge tearing. The inner sheath 4 forms a gusset between the core wires 1, 2.

An electrical protective layer is disposed on the inner sheath 4, the electrical protective layer comprising a metal foil 5 placed therein, a peripheral stranding portion 6 overlying the metal foil 5 and another metal foil placed outside. It includes (7). Both the metal foil 5 and the metal foil 7 are foils made of copper or aluminum at least one of the surfaces of which is covered with a synthetic resin. The inner metal foil 5 has a synthetic resin layer on the surface of the inner sheath 4, while the outer metal foil 7 comprises a synthetic resin layer on the outer sheath side. Advantageously the resin layer of the metal foils 5, 7 is a copolymer of polyethylene. This achieves that the metal foil 5 is attached with the inner sheath 4 and the metal foil 7 with the outer sheath 8. The attachment achieves a bond that prevents edge tearing of the metal foils.

The metal foils 5, 7 are provided longitudinally while slightly overlapping the band edges.

The peripheral stranding portion 6 comprises a plurality of tinned copper wires or copper cords which are stranded in an alternating arrangement direction on the metal foil layer 5. Stranding or peripheral stranding the wire in an alternating arrangement direction has the advantage that the wire can be withdrawn from a fixed outlet. This has long been known under the name SZ-stranding.

Advantageously the outer sheath 8 comprises polyethylene or a flame resistant polymer, for example polyurethane, preferably free of halogenated elements. The coating material may or may not be crosslinked chemically or physically.

The cable according to the invention is particularly suitable for reliable transmission in industrial automation devices as so-called process-field bus-line conductors.

The method of manufacturing the cable or the lead is explained in more detail by FIG.

The conductors 1a and 2a are drawn out from the outlets 9a and 9b and the core insulation is provided by the extrusion machines 10a and 10b. The core wires 1 and 2 then reach the cooling sections 11a and 11b which also function as reservoirs.

In front of or behind the cooling sections 11a and 11b, the core wires 1 and 2 through spray nozzles 12a and 12b which spray a thin layer of wax or paraffin onto the surface of the core wires 1 and 2. On the surface of the separation layer 3 is provided. Alternatively, the separating layer 3 may be provided, for example, by dipping or by mechanically distributing the fibers soaked by, for example, the separating means.

The cores 1, 2 then reach the SZ-stranding device 13, in which the cores 1, 2 are stranded together in an alternating arrangement direction.

The SZ-stranded cores 1, 2 are then provided with an inner sheath 4 in the extrusion machine 14. In the cooling section 15 likewise formed as a reservoir, the inner sheath is cooled.

The first metal foil 5 covered with the synthetic resin is disposed on the inner coating. The metal foil 5 is drawn by the supply reel 16 and is longitudinally advanced by the forming device 17 while the band edges are formed around the inner sheath with a slight overlap.

A stranding layer 6 is disposed on the first metal foil 5. For this purpose, the wires 19 forming the stranding layer 6 are drawn out of the plurality of supply reels 18 shown, and only two of them are foiled in an alternating arrangement direction by the SZ-stranding device 20. 5) is disposed on.

The other metal foil 7 covered with the synthetic resin is drawn out from the supply reel 21 and is formed in a circle around the stranding layer 6 with the band edge slightly overlapped by the forming apparatus 22.

An outer sheath 8 is provided by a sheath extrusion molding machine 23 which is likewise cooled and cured in a cooling section 24 formed as a reservoir. The metal foil 5 adheres to the inner sheath 4 and the metal foil 7 to the outer sheath 8 through the remaining heat of extrusion molding.

Finally, the finished cable is wound on a supply reel or cable drum by means of a winding up device 25.

The method allows for the production of larger cable lengths at speeds up to 100 m / min. The reservoir combined with the cooling section has a volume capacity of 200 m.

The core SZ-stranding device has a performance of at least 3000 strandings / min.

As mentioned above, the present invention has the effect of providing a cable which can be easily stripped and can be manufactured at low cost and a method of manufacturing such a cable.

Claims (14)

a) a cable core comprising at least two cores placed next to each other and provided with core insulation, b) an inner sheath easily removable from the cable core, c) a protective layer, d) an electrical signal transmission cable having an outer cable sheath, 1) The surface of each core wire insulation part 1a, 2a includes the coating part 3 by a separating means, 2) The protective layer comprises a first metal foil 5 provided on the inner sheath 4, a stranding layer 6 made of a plurality of metal wires surrounding the metal foil 5, and on the stranding layer 6. A cable comprising a metal foil (7) laid. 2. Cable according to claim 1, characterized in that the separation layer present on the core insulation (1a, 2a) is a wax layer. 2. Cable according to claim 1, characterized in that the separating layer (3) present on the core insulation (1a, 2a) is a thin layer of nonwoven fabric. Cable according to one of the preceding claims, characterized in that the core insulation (1a, 2a) is a two-layered structure in which the inner layer is soft and the outer layer is rigid. The cable of claim 4 wherein the inner layer comprises an expandable polyolefin. Cable according to one of the preceding claims, characterized in that the inner sheath (4) comprises expandable polyolefin, preferably expandable polypropylene. Cable according to one of the preceding claims, characterized in that the metal foil (5) placed therein is copper or aluminum foil with at least one side coated with synthetic resin. 8. The cable according to claim 1, wherein the inner metal foil is provided on the inner sheath in a longitudinal progression. 9. Cable according to one of the preceding claims, characterized in that the wire is provided on the metal foil (5) in which the stranding layer (6) in alternating arrangement direction is placed. Cable according to one of the preceding claims, characterized in that the wire of the stranding layer (6) is a tinned copper wire. Cable according to one of the preceding claims, characterized in that the metal foil (7) present on the stranding layer (6) is a foil of copper or aluminum, with at least one side coated with synthetic resin. . Cable according to one of the preceding claims, characterized in that the metal foil (7) present on the stranding layer (6) is attached with an outer sheath (8). Cable according to one of the preceding claims, characterized in that the metal foil (7) present on the stranding layer (6) is provided longitudinally. The method of manufacturing a cable according to any one of claims 1 to 14, a) manufacturing a core wire by coating a metal conductor with a synthetic resin, b) providing a separation layer on the core insulation, c) stranding the core into the cable core; d) surrounding the cable core with the inner sheath by extruding the inner sheath; e) placing the longitudinally progressing first metal foil on the inner coating, f) peripheral stranding the first metal foil with a plurality of metal wires; g) placing the longitudinally progressing second metal foil on the peripheral stranding portion; h) extruding the outer coating, wherein steps (a to h) are performed in tandem.