DE2045976A1 - Electrical cable with a metallic sheath surrounding the cable core - Google Patents

Description

Ιο.9.197ο

Electrical cable with a metallic sheath surrounding the cable core

The present invention relates to an electrical cable which consists of a cable core and a cable core enclosing the cable core tubular sheath.

The increasing tendency to lay communication cables in the ground has made it necessary to find means to protect the buried cables against the ingress of moisture Λ . Such protection can be achieved by enclosing the cable core in a waterproof covering or by filling the cable core with a water-repellent compound. However, it is also possible to choose a combination of both measures. If, for example, a metallic cover is used as a moisture barrier, it is often required that the necessary electrical conductivity is ensured because it is used at the same time as a protective cover.

It is already known (U.S. Patent 3,233,036) for manufacture a corrosion-resistant protection for communication cables a ^

aluminum or copper tape of small thickness coated on both sides with plastic to form a tube with overlapped edges over the cable core and to apply the outer plastic jacket over it. Likewise, attempts have already been made (US-PS 3 2o6 5kl) to achieve a tight covering of the cable core of a communication cable by shaping a thin walled metal strip, coated on both sides with a copolymer, into a tube with upstanding edges under the action of heat by melting the polymer are glued together.

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Then the edges connected in this way are opened the cable core bent down. However, such an arrangement does not guarantee moisture- or gas-tightness Enclosure, apart from the limited mechanical strength and electrical conductivity and the need for a relatively expensive raw material for a dubious one Use success. Also occur when winding and unwinding the. Cables on or from drums cause compressive and tensile stresses, which lead to leaks in the adhesive seam.

For the production of longitudinally welded aluminum cable sheaths, it is also known (Siemens Zeitschrift 19 "Vol., No. 8, 1939)» ei * deforming ^one aluminum strip above the revolving cable core by correspondingly shaped Profilwalzexi to a closed tube with flared edges. The welding is carried out by so-called resistance welding between the flared edges at a certain distance from the cable core in order to protect the cable core from overheating during the welding process. In order to remove the welding edge formed by the relatively thick-walled strips, subsequent reworking of the cable jacket is necessary, since the protruding welding edge still has to be worked down by milling, hammering or rolling in order to obtain a smooth, cylindrical cable jacket. Since the cable sheath produced in this way must first have a larger inner diameter for manufacturing reasons than corresponds to the cable soul, it is also necessary here that the welded sheath must be worked down to the cable diameter by a separate tool. An ongoing, operational production and use of cable sheaths made of aluminum in this way, however, presents considerable difficulties. This is especially true when the wall thicknesses of the tapes used are too thin

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passes over, as this is necessary for the resistance welding Press against each other and the jjxact guidance of the belt edges within the permissible limits it is difficult to keep within the permissible limits and the oxide layers present on both sides of the tape make the welding process considerably more difficult, especially with thin strips.

It has also been proposed to use a metal cladding by making the overlapping chews of the thin metal band that is folded around the cable core is to be connected by welding. This method can advantageously be applied to copper strips, but it cannot without further ado because of the surface the overlapping strip edges located oxide layers are applied. Such oxide layers make it extraordinary difficult to achieve a perfect, uniform metallic connection between the belt edges.

The object of the invention is to create a sheathing, preferably made of aluminum, for cable cores that is impermeable to vapor, corrosion resistance and has good shielding properties. Here are simultaneously * ensure flexibility and TrommelbaT = · ness of the cable mechanical properties. This object is achieved according to the invention in that the sheath consists of a longitudinally running metal strip formed into a tube with raised edges with a thickness of at most 0.3 mm, the ends facing away from the sheath with one another to form a homogeneous, closed, electrically conductive tube are connected in a gas-tight metallic manner. Such a cable with a thin-walled metal sheath is characterized by an absolute water vapor barrier with a simultaneous excellent shielding effect due to the high electrical conductivity that is uninterrupted in the circumferential direction.

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Often it can _t particular economic reasons beneficial no, to dig a sheath of aluminum tape, whose oxide-free edges for example, are joined together by welding "

The one from the raised metal connected to one another The web formed by the edges can be bent over onto the surface of the covering and the covering can be covered with a layer of one the metallic surface firmly adhering thermoplastic Be surrounded by polymer. This can provide strength the thin-walled envelope can be further increased. DaxüLei a jacket made of a conventional thermoplastic material can then be applied in a known manner.

Due to the extremely thin metal strips below 0.3 nmi _f, preferably a few! ' than ο, 2 ωιιι, the need for metal is significantly reduced · The small thickness of the bundle also allows the cable to be made easily bendable after bending over the webs formed from the raised edges, and also to be reeled up and down.

For the production of branch or connection points can in continuation it can often be advantageous that the in itself bent web at the connection or splice point i, u a correspondingly constructed cable in the radial direction is bent back. The raised edges are then by means of a suitable square tool to form a longitudinal joint Cavity into which e.g. the Exdungsseül is inserted and through known clamps is held, expanded.

The invention can also advantageously be used where the cable core consists of two adjacent individual cores, each of which is used for mutual shielding by an envelope made of a longitudinal inlet to the pipe ♦ the invention

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The cable can also be designed as a coaxial cable seiii, with an inner conductor and a concentric outer conductor separated from this by a dielectric, from the metal strip of thin wall thickness is constructed according to the invention.

Hos to a cable distribution according to the invention, it is advantageously followed in which around the cable core, a 4-üngseinlaufendes metal strip ^mu with a wall thickness of at most 0.3 and Λ

a width greater than the circumference of the cable core formed into a tube with radially raised, parallel edges will. The ends of the longitudinal web formed in this way facing away from the hollow surface are then joined together gastight, e.g. by welding, soldering or the like. metallically connected to each other. Used as a metal band that Made of copper, steel and the like. Can be made of a band If aluminum is used, the raised edges are trimmed to a defined height with oxide-free Brought cut surfaces and the tape prepared in this way immediately then fed to a welding device, by means of which the edges in the area of the oxide-free cut surfaces be welded. ™

The invention is based on that shown in FIGS Auführungsbeispiele explained in more detail.

Figure 1 shows a cross section through an electrical cable with a jacket or a sheath according to the invention.

Figures 2 and 3 show a cross section similar to that according to of Figure 1 for further embodiments of the invention

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BATH

FIG. K shows a cross section through an electrical cable with a coaxial arrangement of inner and outer conductors.

JTigur 5 is a side view schematically showing the device for making a cable according to the present invention.

FIG. 6 is a cross section taken along line 6-6 of FIG.

Figure 7 depicts a cross-section along line 7-7 of Figure 5.

Figure 8 is a cross-section along line 8-8 of Figure 5

FIG. 9 shows a connection arrangement in a perspective view for cables according to the invention.

Figure Io shows a cross section through a cable with divided dr Soul according to the invention.

FIG. 11 illustrates the structure of a video cable in cross section.

FIG. 12 shows a diagram of the referee characteristics of Cables of the known sheaths with longitudinal Gaps in the jacket and those with a closed envelope according to the present invention.

In a diagram, FIG. 13 also shows comparable properties of cables with a longitudinal gap and such with a closed envelope.

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The present invention is concerned with electrical cables. tubular sheaths made of thin metal strips for the cable core or cores to prevent the ingress of aggressive liquids, vapors or gases *. \ x . The jacket oJüi the cladding is able to withstand mechanical stress. MG cn and shows excellent shielding characteristics. Thin metal bands with a band thickness not exceeding ο.3 mm are used. Aluminum is advantageously chosen as the metal, but copper, steel or other metals and alloys thereof can also be advantageously used.

As shown in FIG. 1, Io means an elek- ™

trischoss cable with a conventional cable core 11, which consists of insulated conductors. The cable core 11 is enclosed in a casing 12 made of a metal strip 13ι which is folded around the cable core 11. The baud 13, for example made of aluminum, has a greater width than the circumference of the core 11 in order to produce a longitudinally extending web lk from the baud edges 15 of the band 13. The edges 15 are bent over from the corners 1G and 17.

The ends l3 of the band edges 15 are close to close over the entire length, since they are prepared for a certain victory height by cutting under them. The resulting lesul- \ ti he end en tXitliYeien ends lö are veibunderi together, for example tiurcli a continuous longitudinal weld 19 * bridging the ends "

The upstanding web lh can be folded over all corners l6 and 17 in order to bring it to rest against the outer surface of the sheath 12, as indicated in the dashed lines. In this way, the cable Io is light Flexible and therefore ideally suited for winding and unwinding and for laying.

1 O Ö 8 1 6 / U 6 5 _ c

BATH ORIGINAL

In contrast to the exemplary embodiment according to FIG. 1, the cable loo according to FIG. 2 has an additional coating made of plastic, which is applied to the outer surface of the sheath 12 and is firmly connected to the metal. This application can take place, for example, by extrusion, coating, electraphoretic deposition and the like. A copolymer of polyethylene, which is enriched with monomers, can be used as the plastic, as described in US Patents 2,987,5ol and 3,027,316 is. The coating 2o has the effect that the casing 12 is resistant to corrosion and contributes to increasing the rigidity of the thin metal strip of the casing. An outer jacket 21 is applied over the coating 2o by extrusion or the like! The jacket 21 can be made of polyethylene, Polyvinjic / jLorid or the like. Consist. The jacket 21 adheres firmly to the coating 2o and contributes in the same way to the protection of the cable loa *

FIG. 3 shows a cable in which the metal strip 13wrher is covered with a plastic layer 2oa which is firmly adhered to the metal and which has a similar structure to the coating 2o. The coating 2oa is applied to the metal strip 13 in such a way that an inner lining results.

The edges 22 of the coating are held away from the ends 18 of the tape and can be set so that they are close together or butted together. The coating 20a can also be applied to the outer surface of the belt 13 or such a coating or coatings are used on both sides to make the casing 12 resistant to corrosion.

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"!" ■ "■ ιί :: '■■« ■■ ■ :: "..' ■■■» ■ - ■

Xn of Figure 4 is "animal placed in coaxial 3o, with the usual internal conductor 31 'which may be tubular, and the outer conductor 32, the ^AUA in a concentric position relative to the Xnnenleiter by an intermediate annular body 33 of a foamed plastic or other suitable dielectric spacers is separated. The outer conductor 32 is formed from a metal band 3 ¹ * which is bent into a tubular shape with a web 35 which is formed by the band edges $ 6 * The band edges at 37 are metallic with one another, as before Λ

described, connected. The web 35 is on the outer Surface of outer conductor 32 bent over · Over the outer conductor Plastic wrappings that adhere firmly to the metal and form the jacket can be applied in a known manner to " to be brought*

Figures 5 to 8 show a device and illustrate a method for dividing a cable Io. The device consists of a forming table T along which the cable core 11, pulled from a supply drum (not shown), is moved along with a metal band M, which is also withdrawn from a supply drum (not shown) and fed to a pipe-forming device ko . This shaping device, known per se, brings the tape into the tubular shape 13 over the cable core to form the sheath 12.

Band M has a greater width than the circumference of the Kal'üLsötälc 11, so that the protruding parts U '· aul'i tchtat ohonduti radially raised? .O & entiM ildn-.lliuntuii I .J Li. * ■ :.' -Α .. · Ί. is l .- ^ ί τΐ '.' Ι, οΜ · inan.loi, tu 1 ι «>» * ί; ηκυΐϋ <ΐίί-α. DLi- An . iriul) : _f , Ιί iv _ä ·.!, '.: 1 JC: ■ 1 i; 'Ulli f J: lli'i 1 i lill £ vLf'i;: rl ί 1>fl;.; ί ·,:

BAD OPHQINAU

ι η -ι ■ '■ ί ■■. μ -,

Io

Form table T to a schematically indicated trimming device 4l out, where the upstanding edges are separated to a predetermined edge height, so that the freshly cut ends 18 are aligned with each other

While the casing prepared in this way is passed through the trimming device kl , the cut-off parts 42 of the webs are removed in a suitable manner. The freshly cut ends 18 are then brought accurately and to scale with appropriate welding devices A3 into alignment "which preferably operate under a protective gas atmosphere of argon or the like, ·, the welding and the metallic bond of the ends of ISS d ·· way" in "r continuous c * ißung rfolgt, "di" which are bridged · di · welding speed can be about 5 m to 24 amount per minute, at a welding current of about 12 to 7o a.

The web 14 produced in this way, which can have a height of approximately 4 to 8 mm, is then bent over in a suitable folding device 44. The coating of the plastic adhering to the metal is ".B. applied by an extruder 45, while the jacket 21 over the coating 2o and in connection with
this is done by an extruder 46 or other suitable means.

The trimming device consists, as indicated in FIG. 6, of a pair of horizontally arranged cutting edges 5o and 5li which are arranged vertically an ^ eurduo t uii '/ -' LLen 52 and 53 for liatation, diüsi- vertically an- ^ aordu: ; do WoLleu -iiiul 111 the camps' rl urrJ. 5 ¹ ? ! i>'■' ■ ■ ^a ö ^et "* · and I 'i. ■ ii £' · :; Lgne t ο means nj.". Ul miller! »Ö / .hi ohm; t

■ ".i; i. ·,. ' M _v f: L 1 i <· 1 / · ΜΧ. :, ',. TU-- i'v!. Ι ί. Ii 1 »C Π -' ■! ·. 'W It ΪΊ <t ■ .; :.;: .- ■ C Ί ι (. Ι i - · · ) '<

BATH ORIGINAL

is arranged on the shaft 52 below the cutting knife 5o outer Ilante of the guide disc 56 is around a little of the horizontally arranged cutting knife 51 removed .. It prevents * the raised edges of the around the cable core bent tape during the cutting process will.

Special guide elements 57 made of plastic or the like lead the arrangement of the cable soles 1 and sheath 12 to the cutting knives 5o and 5l · In this way, the upstanding edges are aligned sufficiently for the application of the welding device ^ 3. In the complete cable arrangement, as shown in FIG. 8, the bent parts 15 T of the web lk lend themselves to further manipulations for the connections of electrical cables or connections ^ of the sheaths 12 to cable ends that are to be spliced or connected to manufacture.

For example, the cables 6o and 6l, as in FIG Figure 9 shown with a thin metallic envelope 12 in a suitable manner both with respect to the

both cable cores, as well as in relation to the sheaths ύ

spliced. The connection ends 62 of the webs 1k are bent back into their original position and connected by a grounding cable 63, whereby they are held in their position by connection terminals 6Λ. The cable cores of cables 60 and 61 are then connected to one another in a suitable manner, as indicated at 66.

This way it is an excellent electrical connection between the »data grounding cable 63 and the sheath 12 h «r («, for example by introducing a suitable

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BAO OWGtNAL

Tool between the bent up band edges of the connecting parts 62 in order to get cavities 65. The ends of the grounding cable 63 are inserted into these cavities 65 and the clamping blocks 6k are then clamped and press the inner surface of the opposing upstanding portions against the wire ends 63 'to ensure the electrical connection of the cables 60 and 6l.

The casing of the cables constructed according to the invention are particularly suited to mutual influencing Eliminate or at least minimize to a minimum that is in some form due to the neighboring Can disfigure the location between pairs in communication cables. Sq is e.g. a cable 7o after the Figure Io, made up of the two juxtaposed Cable units 71 and 72 exist, v the transmission Suitable for both transmission directions of PCM (pulse code modulation) signals. Each unit 71 or 72 is in a casing 12 according to the embodiment described above locked in. An insulating layer 73 ', for example, made of plastic in extruded form or in The form of a tape ^ is applied to the units 71 and 72, üex-covers from an outer jacket construction, which consists of a metal casing 12a, as described above, consists and a jacket layer 21 made of polyethylene, Polyvinj & ÜLoi id or the like. That over the actual envelope Is applied by extrusion or the like.

The cable 7o can furthermore have a plastic coating which is applied directly to the outer surface of the casing 12a. On this is then the Sheath 21 arranged and firmly connected to this. Doing this is an excellent way of transmission and return with excellent mutual Shielding achieved.

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- t 13 -

In the figure, 11 is a video cable is shown, which consists of the two pairs of video 8o and 8L, which are disposed ^l t within the envelope 12, together with a suitable dielectric filler material. 8 The two pairs are provided with a core wrapping 85 », for example made of insulating material. An outer shield 12a, which is made as described above, encloses the pair members 80 and 81 together with a jacket sheath. Other insulated pairs or conductors 86 can be included in this common cable construction. Λ

Such a cable construction avoids the mutual Influence between the video pairs 80 and 81 as well as between the video pairs and other pairs or Ladders 86 included in the cable. The shielding characteristics of the covers 12a, 12 and 3 ^ are particularly noticeable, especially if you compare the known shielding structures that one have longitudinal electrical gap, the one Means interruption of the screen in the circumferential direction.

Thus, the diagram, which is shown in the figure lü, contains the relationship between the ratio of coupling resistance R ^ to direct current resistance R ₀ in ™

Relation to the shielding effect and frequency of the transmitted Signals in MHZ. The curves shown relate to electrical cables with a shield, which is constructed according to the present invention, and on the other hand to shields with a gap, i.e. seen over the circumference, with an interruption of the screen. Such known shielding structures include plastic coated tapes. Metal that overlaps or with the cable core are formed slowly running web, with between

-Ik-

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lh

the metal edges of the plastic bands are attached, which forms the gap and thereby the indicated electrical irregularities seen over the circumference causes.

The diagram shown in Figure Iu relates on cables that now have a diameter of uo an aluminum coating with a wall thickness of ο, <s now. One cable has seen / closed over the circumference Shielding according to the present invention, the other cables have shields that run lengthways Have a gap in the shield. The voltage drop on the outer surface of the screen was shown in units of coupling resistance. As can be seen from the figure, the ratio of coupling falls resistance to DC resistance in shields according to the present invention steeply and exponentially with increasing frequency of the transmitted signals accordingly the solid line. With shields with a gap, however, where a closed envelope is missing over the circumference, it returns beyond a certain frequency the relationship of resistance to sink his endeavor cleanly and, as indicated in the dashed lines, increases with increasing frequency. But that means a pronounced one Decline in the shielding effect. Such a drop sets up with increasing tendency with increasing frequency past the critical point.

This is particularly evident at the point 100 MHz, where the shielding effect according to the invention is accordingly of curve 1 at point A by a factor of at least

3
Io ^{J is} more effective than a shield with a gap of 0.1 mm, which corresponds to point B on curve u.

- / 15 -

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BATH ORIGINAL

The shielding performance for shields with a gap, where the gap has a width of 0.2 mm and 0.05 »m, is illustrated in curves 3 vuaA k in FIG.

FIG. 13 shows another possibility of shielding services of screens provided with a gap and without a gap. Here is the ratio of coupling resistance to a gapped one. Shielding R. and one without

Gap formed shield Rj. Over the frequency ^

mutually influencing signals plotted. So are the values of the ratio RJk. expressed in db,

^R kh
Plotted against the frequency for screens with a diameter of 2o and 8o mm, each with a gap width of o _t 1 mm. At 100 MHz, the shielding effect of a shield with a diameter of 20 mm and a gap of 0.1 mm is reduced by the factor $> o, compared to a shield of the same diameter and the same wall thickness, which has no gap and accordingly over the entire circumference of the present invention electrically forms a closed envelope. λ

The shielding effect of a metallic, closed casing or a pipe can be determined according to known formulas be calculated. At higher frequencies, the protective effect depends on the wall thickness of the envelope and the The depth of penetration of the stream into the material, on the other hand the protective effect depends on a cover and a gap is of:

Cable diameter D Wall thickness of the screen s Gap width b Penetration depth J

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i6

which in turn depends on the specific resistance of the metal and the frequency. The relationship of the coupling resistance of a shield with a gap Rk compared to that of a shield without a gap can be expressed by the following formula:

2s / b \ ² * b 6 ~ l + o, 53 · ./

* kh

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Claims (1)

ίο.9ο 197ο Patontan test 1. Electrical cable consisting of a cable core and a tubular sheathing surrounding the cable core, characterized in that the sheathing consists of a longitudinal metal band formed into a tube with raised edges with a wall thickness of no more than ο , mm, which is attached to the sheathing turned away ends to form a homogeneous, closed, electrically conductive pipe % are metallically connected to one another in a gas-tight manner. ü. Cable according to Claim 1, characterized in that there is a the envelope consists of a metal strip made of aluminum with oxide-free edges, which are metallic with each other Are connected. 3 · Cable according to claim z, characterized in that, last a weld seam bridges the outer ends of the raised edges and connects them to one another. 4. Cable according to claim 1 or one of the following, data etc. characterized in that on the outer surface the ear-shaped envelope a layer of one due to its molecular structure on the metallic Wrapping firmly adhering thermoplastic polymer is upset. 5 · Cable according to claim 4, characterized in that over the layer of adherent polymer a further, with this connected layer made of a thermoplastic material is applied. 109816 / U6S 6. Cable according to claim 1, characterized in that the daii web formed from the raised metal edges connected to one another on the surface of the envelope is bent. 7 · Cable according to claim 6 with a "connecting or splicing point, characterized in that the bent web is attached to connecting or splicing parts for production
an electrical connection with one preferably
appropriately constructed cable is bent back into the radial position. 8. Cable according to claim 71, characterized in that the raised, metallically interconnected canton to form a hollow space ζτ-im imports e.g. an earthing cable are widened. 9. Cable according to claim 1, characterized in that the cable core consists of two adjacent individual cores, each of which is surrounded by a long metal strip formed into a tube with raised edges with a wall thickness of at most
0.3 mm, and at their ends facing the envelope
Ends are connected to each other in a gas-tight manner. Io. Cable according to Claim 1, having an inner conductor and a
concentric to this outer conductor separated by a dielectric νυη the inner conductor, characterized in that the outer conductor consists of a long metal strip formed into a tube with raised edges with a wall thickness of at most 0.3 mm, which ends away from the dielectric are gas-tight and metallic with one another are connected. 1 0 9 8 T 6 / U 6 5 BAD ORtQrNAt 11. Method for the division of an electrical to a or secure the claims 1 to Io, characterized in that that around the cable core a long running one Metal band with a wall thickness of at most o, J now and a width greater than the circumference of the cable core to the Ilohr with radially pulled up, ends running parallel Canton shaped and those turned away from the pipe surface Ends of the thus formed longitudinal The web is smoothed together by welding, I / o th odex- dexgl. be metallically connected to each other. la · The method according to claim 11 with a metal strip Aluminum, characterized in that the raised Edges by trimming on a defined Brought height with oxide-free cut surfaces and the band prepared in this way immediately afterwards one Welding device is supplied, by means of which the Edges welded in the area of the oxide-free cut surfaces will. Ij. A method according to Anspi-uch H, characterized in that "are bent the welded edges on the pipe surface, and that subsequently the so prepared tube a layer of a molecular weight due to its thermoplastic polymer and also a jacket made of a thermoplastic material, for example based Polyvinyl chloride, is applied, both layers are bonded together. 1 * 1. Method of manufacturing an electrical cable according to one or more of claims 1 to Io, characterized in that initially the cable core 9816/1465 is overmolded with a thermoplastic polymer, after which the metal strip is around the overmolded cable core Shaped into a tube with radially raised, parallel edges, the edges metal together be connected and bent and that finally an outer layer made of a thermoplastic Plastic is applied, the extrusion temperature of which, with the appropriate pressure, the bonding of the lower Layer with the metal band causes. 109816 / U65