GB2031042A

GB2031042A - Steel Wire Cable

Info

Publication number: GB2031042A
Application number: GB7925310A
Authority: GB
Original assignee: December 4 Drotmuvek
Current assignee: December 4 Drotmuvek
Priority date: 1978-07-26
Filing date: 1979-07-20
Publication date: 1980-04-16
Also published as: HU176944B; DE2930199A1; BE877897A; DD145118A1; IT1127099B; DE2930199C2; GB2031042B; FR2433608B1; IT7983426A0; FR2433608A1

Abstract

A multi-layer steel wire cable is made up of strands (3, 4, 5) of wire (1, 2) of two thicknesses only and arranged as a core (10) surrounded by several layers (11, 12, 13). One layer (12) contains alternate strands (2, 4) respectively of seven and four wires of equal thickness. The thicker wires (1) are used for the outermost layer (13). <IMAGE>

Description

SPECIFICATION Wire Cable Made Exclusively of Steel Wire The invention relates to wire cables not being provided with hemp insertion and made exclusively of steel wires. The wire cable proposed can be equally used as a runner or as a stationary cable.

In the field of application of wire cables, in connection with the general tendency of technical development a requirement has come into the limelight, in so far as the wire cable should have possible smallest nominal diameter for a given load. The tendencies regarding to the small nominal diameter exerts a far-reaching influence on the equipment and structure, respectively, incorporating the wire cable. Simultaneously with the reduction of the nominal diameter the dimensions of the cable drum and of the auxiliary structures belonging to it can be diminished, too; space requirement becomes less and assembly is also facilitated.By using identical nominal diameters, the problem of the higher tearing or rupture force could not be solved merely by making the wires forming the steel wires of steels of higher tensile strength, since steels of higher tensile strengths have resulted in stiffer cables. In order to increase the tearing (breaking) strength belonging to identical diameters the hemp insertion has been omitted with certain newer cable types. The wire cables built-up of the steel wires have been formed of wires of different thicknesses and in general of braidings formed of said wires.

In case of wire cables one of the requirements lies in-beside the suitable tearing strength-the satisfactory compactness of the wire cable. By the compactness of the wire cable the ratio of the square-sum of the diameters of the wires forming the wire cable and of the nominal diameter of the wire cable is meant. Compactness of the wire cable has been imperative not only because of the advantages resulting from the decreased dimension but also in respect of corrosion resistance. The aggressive media damaging the wires cannot penetrate to the inner strands of a more compact wire cable, respectively to the wires; as a consequence, the extent of destruction caused by corrosion will be also less.

Another requirement to be met has been that the wire cables should be flexible. In order to be able to increase flexibility, wires of smaller diameters but in larger quantities are generally used. On the other hand, wire cables of the said structure are less resistant to abrasion and corrosion. Resistance to abrasion of the wire cables is also a most important requirement. In case of wire cables we differentiate between internal abrasions and external abrasion.

By external abrasion the wear of the wires and strands forming the outer coating of the wire cable is meant resulting in general from the friction between the wire cable and the contacting structural elements, such as the cable drum, the deflecting coils etc., whereas the internal abrasion is a consequence of the mutual displacement of the strands and wires inside of the wire cable. When applying a load to the wire cable, due to the lateral pressure exerted on the wire cable and to the different loads applied to diverse points of the cross-section of the wire cable, the strands and the wires are displaced to different extents. As a result of said displacements frictions are generated on the surface of the strands and wires. We have to point out that resistance to abrasion represents a factor which highly influences the useful life of the wire cable.In order to increase useful life, when preparing wire cables, two solutions are kept in view. According to one of the solutions the height of the thread is kept on a constant value, while in case of the other solution the value of the angle of pitch is kept unaltered within the wire cable.

It is known by experience that in wire cables, where the height of the thread is kept on a constant value and other circumstances are also identical, compared to the useful life of cables, where the angle of the pitch is constant, the multiple of the service life can be achieved. The constancy of the angle of the pitch can be maintained when the diameters of the wires forming the wire cable are identical. Preparation of a wire cable consisting of wires of identical diameters is much easier, but-as already said before-the useful life is considerably shorter.

In wire cables, in which with a view to increase useful life the height of the thread of the wire is kept at a constant value, the wire is to be built-up of wires having different diameters. In wire cables consisting of wires of different diameters, the strands and wires, respectively, perform a considerable mutual displacement, come into contact with each other along a line and not in single points; said circumstances considerably reduce the internal wear. Cables having a Sealetype, or respectively Warrington structure represent a characteristic type of the wire cables consisting of wires with different diameters; in these cables of known structures hemp insertions are also used, thus these kinds of cables, although having a longer useful life due to the reduced internal abrasion, have a larger nominal diameter in proportion of the tearing strength to be obtained with them.A further disadvantage of said type of cables lies in that corrosion resistance cannot be considered as satisfactory.

A further requirement lies in the defOrmation resistance, dimensional stability and inconsiderable rotation of the cable. Deformation resistance and dimensional stability may be increased by means of the compactness of the wire cable. Rotation of the wire cable can be preferably reduced by twisting the wires and strands, respectively in different directions.

Cables consisting exclusively of steel wires are mostly used as stationary cables (stationary cables are carrying cables and the supporting cables). The carrying cables with helical structures represent the most characteristic cables of this kind. The helical cable is twisted of relatively thick wires. These cables neither meet the requirement in respect of corrosion resistance, nor are they sufficiently flexible; as a consequence, they are unsuitable for runners.

In the known wire cables with closed or semiclosed structures there is an external layer formed of profiled wires, arranged on the internal part having an essentially helical structure, the task of said layer is to prevent the penetration of corroding agents into the inside of the cable structure. In spite of their numerous advantages, said cable types are not very much used, since the production thereof has been complicated and expensive.

Wire cables are known, in which the wire cables are built-up exclusively of steel wires in such a manner that the strands are formed of wires with different diameters; such a solution has been specified in Hungarian Patent No. 1 66 184; in this cable structure neither resistance to corrosion nor compactness of the cable can be achieved and taking the nominal diameter into consideration, the wire cable described can be considered as disadvantageous in respect to tearing strength. A further disadvantage lies in that the external strands comprise nineteen wires resulting in a rather complicated production.

Not often are found wire cables built-up exclusively of steel wires, in which an increased compactness has been strived for; these wire cables are composed of wires having various diameters (more than four different diameters), whereby this circumstance renders the production complicated and expensive.

In general, it can be demonstrated that if a known wire cable structure a certain requirement is met to a larger extent, it happens at the expense of one of more other requirements.

By using the wire cable according to the invention the disadvantages described can be eliminated or reduced, whether they appear in course of the production or present themselves during application.

The aim of the invention has been to ensure a compactness for the wire cable-in spite of the fact that it is built-up exclusively of steel wires which, compared to known solutions yields improved corrosion resistance and compactness, besides flexibility and resistance to abrasion are also increased, having furthermore a most simple construction which does not demand special technology and additional costs.

The aim set can be achieved by means of the wire cable according to the invention, which is built up of wires in two thicknesses; the strands each contain at least one layer incorporating mixed strands with different numbers of wires.

The proposed wire cable contains the most simple strand structure, i.e. strands comprising four, respectively seven, wires. Preferably, the strands formed of wires of smaller diameters are arranged in the inner layers of the wire cable, while the strands incorporating the wires with larger diameters form the external layer(s) of the wire cable. In the solution according to the invention the contact of the strands and wires, respectively along a line, already described in the foregoing, can be well ensured. Therefore the essence of the wire cable according to the invention lies in that in the single layers there are either strands comprising seven wires, or strands incorporating seven and four wires, furthermore, that the wires contained in one strand are of identical diameters.

In a preferable embodiment of the wire cable proposed, the strand forming the core of the wire cable, as well as the first layer encircling the same and the strands of the second layer lying outside of the first one are formed of thinner wires.

In a further preferable embodiment of the invention, on the two layers enclosing the core there are two external layers arranged and the latter ones are twisted in an opposite direction.

The wire cable according'to the invention will be described in detail by means of the drawings enclosed showing the preferable embodiments of the invention, where Figure 1 is a cross-section of the embodiment of the wire cable according to the invention, in which the core is enclosed by three layers, Figure 2 illustrates the section of the embodiment of the invention having one more external layer than shown in Figure 1.

In the wire cable according to the invention illustrated in Figure 1, wires 1 having a larger cross-section and wires 2 having a smaller crosssection have been used. The structure of the wire cable consists of seven-wired strand 3, four-wire strands 4 and seven-wire strands 5.

the only difference between the seven-wire strands 5 and the seven-wire strands 3 lies in that the wires forming the strands 5 have larger diameters. In the embodiment described here, the seven-wire strand formed of the wires 2 of smaller diameter constitute the core 10. The first layer 11 following the core is formed of six strands, which is enclosed by the second layer 12.

Said second layer alternately contains seven-wire strands 3 composed of the wires 2 with the smaller diameter and four-wire strands 4. The outer layer 13, consisting of the seven-wire strands 5 formed of the thicker wires 1 form, as it were, the coating of the wire cable.

The difference between the embodiment illustrated in Figure 2 and the solution according to Figure 1 lies in that in this case a further outer layer 14 has been applied. From the Figure it emerges that the core 10 is formed of a sevenwire strand made of the wires 2 with the smaller diameter, followed by the first layer 11 composed exclusively of the seven-wire strands 3, the following one being the second layer 12, containing alternately four-wire strands 4 and the seven-wire strands 3. Said layer is encircled by the external layer 13 formed by seven-wire strands 5 built-up exclusively of the thicker wires 1; outside of said layer a further external layer 14 has been arranged. The external layers 13 and 14 are twisted in opposite directions.

In the wire cables described here for sake of an example, in the critical place, in the second layer 12, the four-wire strands 4 and the seven-wire strands are alternately arranged; as a consequence, the constancy of the height of the thread within the structure of the wire cable can be ensured, i.e. the contact of the wires along a line should be a prevailing feature of the cable.

By means of results obtained in practice it was demonstrated that the compactness and tearing strength of the wire cable according to the invention-compared to the traditional wire cables built-up of wires having identical nominal diameters and indentical values of tensile strength-could be increased by 1 5 to 35%. It could be proved by tests that the wire cable according to the invention displays an improved flexibility, a better resistance to abrasion and deformation, when compared to known cables.

The rotation of the embodiment shown in Figure 2 is far more advantageous than wire cables of traditional structure.

Taking into consideration that the wire according to the invention is built-up of wires of not more than two different diameters, as well as that it incorporates strands with the most simple possible structure, production does not require complicated equipments, simultaneously costs of production are also low.

The reference numbers appearing in the appended claims are solely for the purpose of illustration and not of limitation.

Claims

1. Wire cable consisting exclusively of steel wires, containing layers constituted by strands formed of steel wires characterized in that in each individual layer there are either seven-wire strands (3, 5), or four-wire strands (4) and seven wire strands (3, 5), and the individual strands contain wires (1, 2) of identical thicknesses.

2. Wire cable as claimed in claim 1, characterized in that it consists of wires (1, 2) of different thicknesses.

3. Wire cable as claimed in claim 2, characterised in that the strand forming the core (10), as well as the first layer 1) encircling the core and the strands of the second layer (12) are formed of thinner wires (2).

4. Wire cable as claimed in any of claims 1 to 3, characterized in that at least in one of the layers the four-wire strands (4) and the seven wire strands (3j are alternately arranged.

5. Wire cable as claimed in any of claims 1 to 4, characterized in that on the two external layers enclosing the core (10) there are further external layers (13, 14) which are twisted in opposite directions.

6. A multi-layer wire cable comprising strands of wires which are of two different thicknesses (diameters) only and which are exclusively of steel, at least one layer incorporating strands containing different numbers of wires.

7. A cable according to any preceding claim, wherein the cable has a core and at least four layers around the core, the two outermost layers being formed of strands twisted in mutually opposite directions.

7. A wire cable substantially as herein described with reference to and as shown in Figure 1 or Figure 2 of the accompanying drawings.

New Claims filed on 4 December 1979.

Superseded Claims 1 to 6 inclusive.

New Claims:

1. A multi-layer wire cable comprising strands of wires which are of two different thicknesses (diameters) only and which are exclusively of steel, at least one layer incorporating strands containing different numbers of wires, the wires in each strand of said at least one layer being of the same thickness (diameter).

2. A cable according to claim 1 wherein in each individual layer there are either seven-wire strands or four-wire strands and seven-wire strands.

3. A cable according to claim 1 or claim 2 wherein the individual strands of each layer contain wires of identical thickness (diameter).

4. A cable according to any preceding claim, wherein there are at least three of said layers present and the said at least one layer is an intermediate layer.

5. A cable according to claim 4, wherein the strand forming a core and two layers next to the core are formed of thinner wires than the layers disposed outwardly from the said two layers.

6. A cable according to any preceding claim, wherein said at least one layer consists of alternating four-wire strands and seven-wire strands.