GB2176926A

GB2176926A - Electric cable

Info

Publication number: GB2176926A
Application number: GB08615150A
Authority: GB
Inventors: Friedrich Schauer; Jurgen Boll; Werner Saletmaier
Original assignee: Kabelmetal Electro GmbH
Current assignee: Kabelmetal Electro GmbH
Priority date: 1985-06-22
Filing date: 1986-06-20
Publication date: 1987-01-07
Also published as: IT8648165A0; GB8615150D0; DE3522335A1

Abstract

An electric cable has a sheath (3) and insulated wires (5) in the form of a ribbon cable (2). To give sufficient flexibility to the ribbon cable (2) the wires (5) are firmly joined to a ribbon-shaped base (6) only in limited areas (H), whereas there is no adhesion at intermediate disjunctive areas (T). At the areas of adhesion (H), the wires (5) are firmly located with predetermined spacing so that they can be provided with contacts in a simple manner. Adjacent wires may be twisted together except at the areas of adhesion (Figure 11). Optionally a wire mesh shield (4) may be provided. A base (6) may be provided on both sides of the wire (Figures 4 and 8). Apparatus for making the ribbon cable are disclosed wherein rollers (10 Figure 7, 13 Figure 9) of circular or segmented section are applied intermittently to the base (6) and wires (5). A roller having grooves of varying depth may alternatively be used (Figures 10a and b). <IMAGE>

Description

SPECIFICATION Electric cable and method for producing it This invention relates to an electric cable comprising a plurality of insulated electric wires which are combined to form a cable core of generally circular cross-section and are surrounded by a common sheath of insulating material; the wires being combined, at least along sections thereof, at a predetermined distance from each other, into a ribbon cable which is shaped to form a generally round elongated structure; and the combining of the wires being discontinued, over the entire width of the ribbon cable, at disjunctive areas which are distributed along the entire length of the ribbon cable and are distanced axially from each other. The invention also relates to a method for producing this cable. Such a cable and production method are described in EP 0136040.

Such electric cables advantageously combine the advantages of round cables, on the one hand, and flat ones, on the other hand. Where long stretches are to be bridged and where good flexibility is required, the round cable is particularly valued, its good flexibility is not impeded by the fact that a ribbon-cable structure is present, since this is very flexible, even in the form of a round structure, due to the disjunctive areas distributed along its entire length. At the ends of the cable, at which the wires are to be connected to electric contacts, one obtains the advantage of a ribbon cable, in which the wires are combined at a fixed spacing. As a result, connection to the correct contacts can be carried out very simply, and in particular prepared contact strips can be used.Another general advantage of these cables is that the wires can be electrically shielded in a particularly simple manner by applying a round shield.

Although the known cable of EP 0136040 has the advantages specified, it is very expensive to produce. The ribbon cable with disjunctive areas may for example be produced in the form of an array of electric conductors provided with a common extruded insulation, which must be subsequently cut open, in a disjunctive area, between the wires. Another possibility consists of using prefabricated single wires which are combined by means of an adhesive or by heat to form a ribbon cable, leaving the disjunctive areas free, however. In the first case, very great care must be taken to ensure that the cuts are made precisely at the correct location, so that the insulation of the individual wires is not damaged. If the insulation is accidentally damaged, the entire ribbon cable is unusable.In the second case, considerable care must be taken to ensure that the disjunctive areas as such are retained.

Since the adjacent wires are to be joined to each other along lateral surface lines, it will be difficult to produce the desired ribbon cable by bonding or welding unless special measures are taken to mask the workpieces in the disjunctive areas.

It is an object of the present invention to provide an electric cable as first mentioned herein whose disjunctive areas can be simply produced, in a predetermined axial length, without risk of damage to the insulation.

According to the invention, there is provided an electric cable comprising a plurality of insulated electric wires which are combined to form a cable core of generally circular cross-section and are surrounded by a common sheath of insulating material; the wires being combined, at least along sections thereof, at a predetermined distance from each other, into a ribbon cable which is shaped to form a generally round elongated structure; and the combining of the wires being discontinued, over the entire width of the ribbon cable, at disjunctive areas which are distributed along the entire length of the ribbon cable and are distanced axially from each other; wherein the wires of the ribbon cable are firmly joined by adhesion to at least one common ribbon-shaped base extending over the entire length and width of the ribbon cable, and the adhesion between the base and the wires is interrupted at the disjunctive areas.

The present ribbon cable can be obtained by a procedure including the following steps; (a) a plurality of insulated electric wires extending parallel to each other is passed jointly with at least one ribbon-shaped base through the gap between two rollers; (b) the wires and the base are firmly joined to each other by the pressure of the rotating rollers, heat simultaneously being supplied; and (c) the pressure of the rollers is discontinued at intervals.

The discontinuation of the pressure can be achieved in a particularly simple manner by increasing the gap between the two rollers. No covering measures are required, and the heat supply does not need to be interrupted. Wires and base remain unjoined at the disjunctive areas if the pressure is not applied.

This technique has the particular advantage that, in the disjunctive areas, pairs of wires may be formed by the twisting together of two adjacent wires in each case. This is especially desirable, for example, when the ribbon cable is to be used for telecommunications purposes, in which decoupling of different transmission circuits is desired.

The invention will be more fully explained with reference to the accompanying diagrammatic drawings, in which; Figure 1 shows a cable according to the invention with partially removed sheath; Figure 2 is a top view of a possible form of ribbon cable; Figures 3 and 4 are cross-sections through ribbon cables of different constructions; Figures 5 and 6 are cross-sections through cables of different constructions; Figures 7 and 8 show two forms of production device; Figure 9 shows a modified form of production device.

Figure 10 shows profiles of rollers which can be used in the production devices.

Figure ii is a top view of a modified ribbon cable.

Figure 1 shows an electric cable 1 in whose core a plurality of insulated electric wires is present, which are combined in the form of a ribbon cable 2. A sheath 3 (Figures 5 and 6) preferably consisting of plastic is applied over the core. A shield 4 (Figure 6) which is preferably of wire mesh and which is enclosed by the sheath 3 can also be provided around the core. Copper wires, which can also be tinned, can be used for the shield. It is also possible to construct the shield from an aluminium foil with a wire mesh provided around it.

The ribbon cable 2 consists of a plurality of wires 5 which are arranged adjacent to each other and extending parallel to each other. In Figures 2 to 4, only six wires 5 are shown, for the sake of simplicity. The actual number of wires is considerably higher. The wires 5 are applied to a common base 6 consisting of insulating material, and are firmly joined to the base, section by section. The areas in which wires 5 and base 6 are firmly joined to each other are designed by H in Figure 2, whereas there is no adhesion between the wires 5 and the base in the intermediate disjunctive areas T. Such a ribbon cable 2 is relatively very flexible, because of the disjunctive areas T, even if it has been shaped to form a round structure. Preferably the lengths of the areas T and areas H have an approximate ratio of 20:1.

In the adhesive areas H, the wires are firmly located at a spacing which can be accurately adjusted. When the ribbon cable 2, after removal of the sheath 3, is separated in one of the adhesive areas H, and is spread out as in Figure 1, the wires 5 become accessible at the end, in accordance with the spacing pattern adopted. A prepared plug-in component 7, which is shown only diagrammatically in Figure 1, can then be applied to the end of the ribbon cable 2. The plug-in component 7 contains a number of contact members, these being sufficient for the number of wires 5, and having the same spacing as the wires 5; the component 7 can be equipped, for example, with self-cutting contacts.

As shown in Figures 2 and 3, the wires 5 can be connected to a base 6 on only one side. However, as shown in Figure 4, it is also possible to apply a base 8 to the other side of the wires 5, which base 8 is firmly connected to the wires 5 in the same areas H as the base 6, whereas there is no adhesion in the disjunctive areas T.

To bring the ribbon cable 2 into the form of a core of a cable as shown at 1 in Figure 1, it can be squeezed together to form a round structure. However, it is particularly appropriate to shape the ribbon cable 2 to form an approximately round structure by bending it in the longitudinal direction as indicated in Figures 5 and 6.

The ribbon cable 2 can be produced, for example, in the following manner. A ribbon-shaped base 6 (Figure 7) is pulled off a coil 9, and is passed, together with the wires 5, through the gap between two rollers 10 and 11. By heating the wires 5 and/ or the base 6, or also by heating the rollers 10 and 11, the wires 5 and base 6 are firmly joined to each other between the rollers. So that no adhesion occurs at the disjunctive areas T, the roller 10, for example, can be moved upwards at certain intervals, as indicated by the double arrow 12, and subsequently lowered again. The widening of the gap between the two rollers 10 and 11 can also be achieved by moving both rollers, at the same time, in opposite directions.

To produce the disjunctive areas T, a roller can also be used which is reduced to a circular segment 13, as shown in Figure 9. Naturally, both rollers can be constructed in this manner. Again, for better guidance of the wires 5 and base 6, the circum-ferential area of the roller or rollers can be reduced, by enlarging the guide grooves as shown in Figure 10. Thus Figure 10a shows the profile of the rollers 10 and 11 for the area in which the wires 5 are to be joined to the base 6 by pressure, the depth of the grooves 14 here being such that the wires 5 are pressed against the base 6, whereas, for the disjunctive areas, the grooves 14 are so enlarged (Figures 10b) that no pressure is exerted on the wires 5. Thus, the latter are not joined to the base 6.

If the ribbon cable 2 is to be provided with a base on both sides of the wires 5, a device as shown in Figure 8 can be used for its production, in which device a second base 8 is wound off a coil 15, and is introduced into the gap between the two rollers 10 and 11.

The ribbon cable 2 having at least one base 6, in which adhesive and disjunctive areas alternate, offers the further advantage that, in the disjunctive areas, pairs of wires can be formed by the twisting together of two adjacent wires 5 in each case, as shown in Figure 11. This possibility is of significance more particularly where the cable 1 is to be used for telecommunications purposes, since wires 5 used for difference voice circuits are decoupled by the crossing or twisting. Since no pressure is exerted on the wires in the twisted areas, there is no risk of damage to these wires in the production of the ribbon cable 2. The wires 5 are preferably twisted together with the twist direction reversing from each twisted stretch to the next, since in this case no operations entailing continually rotating in only one direction are needed.

It will be understood that the invention has been described above purely by way of example, and that various modifications of detail can be made within the ambit of the invention.

Claims

1. An electric cable comprising a plurality of insulated electric wires which are combined to form a cable core of generally circular cross-section and are surrounded by a common sheath of insulating material; the wires being combined, at least along sections thereof, at a predetermined distance from each other, into a ribbon cable which is shaped to form a generally round elongated structure; and the combining of the wires being discontinued, over the entire width of the ribbon cable, at disjunctive areas which are distributed along the entire length of the ribbon cable and are distanced axially from each other; wherein the wires of the ribbon cable are firmly joined by adhesion to at least one common ribbon-shaped base extending over the entire length and width of the ribbon cable, and the adhesion between the base and the wires is interrupted at the disjunctive areas.

2. A cable according to claim 1, wherein a ribbon-shaped base is applied to both sides of the wires.

3. A cable according to claim 1 or 2, wherein, in the disjunctive areas, pairs of wires are formed by the twisting together of two adjacent wires in each case.

4. A cable according to claim 1, 2 or 3, wherein a metallic shield is applied around the ribbon cable which is shaped to form a round structure, and the sheath is disposed around this shield.

5. A method for producing a cable according to claim 1, wherein a ribbon cable is obtained by a procedure including the following steps: (a) a plurality of insulated electric wires extending parallel to each other is passed jointly with at least one ribbon-shaped base through the gap between two rollers; (b) the wires and the base are firmly joined to each other by the pressure of the rotating rollers, heat simultaneously being supplied; and (c) the pressure of the rollers is discontinued at intervals.

6. A method according to claim 5, wherein the gap between the two rollers is increased at intervals of time.

7. A method according to claim 5 or 6, wherein, in the disjunctive areas, pairs of wires are formed by the twisting together of two adjacent wires in each case.

8. A method according to claim 7, wherein the wires are twisted together with the twist direction reversing from each twisted stretch to the next.

9. A cable according to claim 1, substantially as described with reference to any Figure or Figures of the accompanying drawings.

10. A method according to claim 5, substantially as described with reference to any Figure or Figures of the accompanying drawings.

11. A cable produced by a method as claimed in claim 5, 6,7, 8 or 10.