EP3325711B1 - Hybrid stranded conductor - Google Patents

Description

The invention relates to a hybrid strand having a core and outer wires arranged around said core, wherein at least a part of the outer wires are compacted, the compressed outer wires have a flattened cross-sectional shape, the outer wires are made of steel and the core is a fiber core.

Furthermore, the subject of the invention is a rope with several such hybrid strands.

Moreover, the invention also relates to a method for producing such Hybdridlitzen.

In the US 5,946,898 A is a wire rope with an independent wire rope core known. Described is also a cable assembly of hybrid strands, which have a fiber core and arranged around this wires; This rope is used as a core rope inside the total provided wire rope. The aim of this known rope is to avoid moving wires or strands within the cable structure, and it is proposed to compress the entire cable and thereby reduce the cross-section of the compacted rope compared to the uncompressed cable.

The DE 1 920 744 relates to an aluminum-steel overhead line with an aluminum jacket of at least one layer of circular segment-shaped individual wires, wherein the aluminum layer surrounds the steel core without significant gap and in particular is pressed to the steel core by a hydraulic press. The document refers to a rope, but not to a hybrid strand. Due to the materials used, the rope also has a relatively high weight.

The US 3, 142, 145 discloses a device for spirally stranding a cable core with reinforcing wires which have a non-circular cross section, in particular a trapezoidal cross section. The reinforcing wires are provided in this predetermined form on a spool to be stranded with the core. This document also does not relate to a hybrid strand but to a cable.

The DE 125643 relates to a carrying cable for cable cars whose core is formed by a wire screw or a plurality of interlocking wire screws with a common longitudinal axis, in which wire screws a hemp rope is inserted. To the core of wire screws and hemp rope individual form wires are stranded, which are formed in cross-section S-shaped. This document is not directed to a hybrid strand.

The EP 1 160 374 A2 discloses a cable for windows in motor vehicles with a core strand and with eight external strands disposed therearound. The core strand has a synthetic fiber core element with six internal steel wires wound around it and twelve external steel wires wound around the internal steel wires. The core strand is compacted with the external strands before twisting. In this case, the cross section of the internal and external steel wires of the core strand is deformed with respect to its original circular cross section, and these steel wires come into surface contact with each other.

In contrast, it is an object of the invention to provide hybrid strands with a comparatively small diameter or with a comparatively high breaking force, in relation to a predetermined diameter, wherein the hybrid strands or a rope made from these hybrid strands should also have a relatively low weight.

The invention accordingly provides a hybrid strand having a core and outer wires arranged around said core, wherein at least part of said outer wires are compacted, said compressed outer wires have a flattened cross-sectional shape, said outer wires are made of steel and said core is a fiber core in that a side flattened portion of a first compressed outer wire is spaced from a side flattened portion of an adjacent compressed outer wire. The present hybrid strand can of course have several layers of outer wires or wires around the core, wherein the importance of the mutual contact of the outer wires, in the outer Position, during production, and their compression is up to a flattening of the cross section. The outer wires are made of steel; the core is a fiber core, ie a core of natural fibers or plastic fibers, with plastic fibers being preferred because of their higher load capacity.

The outer wires may have an approximately trapezoidal or circular segment-shaped cross-sectional shape.

Preferably, the distance between the opposing flattened areas is at least partially substantially constant.

The compaction of the outer wires is performed using a known compaction tool. A special feature is that in the present case not a rope made of a plurality of hybrid strands is compacted by means of such a compaction tool, as in the aforementioned US 5,946,898 A but that components of the rope, namely the hybrid strands, are already densified prior to the production of the final rope.

It should be mentioned that ropes made of uncompressed hybrid strands have a comparatively low breaking strength at the same diameter compared to compacted solid steel ropes. In order to achieve a breaking strength comparable to solid steel ropes, an uncompressed hybrid rope must have a larger diameter, thereby providing a higher weight, apart from the extra cost of such a rope.

Due to the compression of the hybrid strands provided here, the outer wires are cold formed, and the cross section of the outer wires is flattened, starting from a round cross section, in particular an approximately trapezoidal or circular segment-shaped cross section is obtained. It is essential that the voids between the wires are minimized by the compression process, wherein the relative metallic cross-section and thus the breaking strength of the hybrid braid is significantly increased.

Thus, with the present hybrid strands, a comparatively lightweight compacted hybrid cable can be obtained which, given the same nominal rope diameter, can have a lower weight per unit length and a higher specific strength compared with a compacted steel cable.

Advantageously, the rope made from the present hybrid strands may be a non-rotating rope, i. the torques of the hybrid strands can cancel each other out or at least largely compensate each other with a corresponding arrangement within the rope, unlike conventional hybrid cables, in which a fiber core is surrounded by solid steel wire strands, then no freedom of rotation can be achieved because the torques of the fibers and the steel wires are too different.

The method according to the invention for producing the hybrid strands, in which outer wires made of steel are beaten and compacted around a fiber core, wherein the outer wires in the still uncompacted state have at least almost contact, while the compression touch each other in a lateral contact area, preferably flat, and wherein at least a part of the outer wires after compaction has a flattened in the contact area cross-sectional shape, characterized in that the outer wires during compaction vault-like support each other and the outer wires are pressed during compaction before the vault formation against the fiber core and after compaction by a corresponding Spring back dimension so that the deformed outer wires of the compressed hybrid strand are slightly spaced.

In the compacted strands of wire, any inner wires should have the same transverse compressive stiffness as the outer wires, ie the wires of the outer wire ply, and thereby the wires can build up the back pressure needed to deform the outer wires. A fiber core per se, however, could not withstand the external pressure of a compaction tool (eg rollers, die or hammers); the fiber core gives way rather. As a result, the outer wires can not be sufficiently deformed per se. After a "compaction", ie passing a compaction tool, therefore, the hybrid strand can spring back again, ie if the back pressure is built up only by the fiber core, the wires will move radially outward again after compression, leaving no significant deformation of the wires. In the present method, on the other hand, the fiber core yields at most until the wires, in particular wires of an outer layer in the case of multiple layers of wires, completely contact each other. In this case, these outer wires support each other during the compaction in the manner of a vault. By this mutual support of the wires as a result of the vault formation of the entire radial pressure acts during compression on the outer wire layer, and the desired plastic cold deformation of the outer wires can be done. Since the wires were pressed a little against the fiber core during compaction prior to vaulting, they rebound after compression by a corresponding amount, so that the deformed wires of the compacted hybrid strand are slightly spaced.

To achieve this "vaulting" a corresponding number of outer wires, with a corresponding wire diameter and corresponding impact angle of the rope wires, provide, as can be found in practice, depending on the overall dimensions of the rope to be manufactured easily.

For example, the combination of eleven wires with a diameter of 0.85 mm and a throw angle of 17 ° has been found to be favorable to produce a compressed 3.8 mm diameter hybrid strand. However, the number of outer wires may be, for example, from 3 to 20, wherein the range of 8 to 14 has been found to be particularly favorable due to the weight distribution between the fiber core and outer wires. The impact angles can be from 5 ° to 30 °, depending on the number of wires, with the range of 15 ° to 25 ° has proven to be particularly favorable. Depending on the choice of wire diameter, this results in hybrid strands with different diameters. The degree of compaction is determined by appropriate dimensioning of the initial and final diameters. Here, a diameter reduction of the strands is possible by a compression in the range of 2% to 20%, depending on the number of outer wires, with the range of 4% to 10% has proved favorable.

Overall, by the present technique, using steel wires, ropes with hybrid strands can be obtained, which, when they have the same breaking strength as a conventional steel cable, have a weight that is about 30% lower, or a comparatively similar weight have significantly higher breaking strength.

• Fig. 1 schematisch in axonometrischer Darstellung einen Abschnitt einer Hybridlitze noch vor der Verdichtung der äußeren Drähte;
• Fig. 2 eine gleichartige axonometrische Darstellung dieser Hybridlitze während der Verdichtung der Drähte der Außenlage;
• Fig. 3 einen Querschnitt durch ein nicht drehungsfreies Hybridseil mit derartigen Hybridlitzen; und
• Fig. 4 ein drehungsfreies Hybridseil unter Verwendung von derartigen Hybridlitzen.

The invention will be described below with reference to preferred embodiments, to which it should not be limited, with reference to the drawings even further. In the drawing show:

• Fig. 1 schematically in axonometric view of a section of a hybrid strand before the compression of the outer wires;
• Fig. 2 a similar axonometric representation of this hybrid strand during the compression of the wires of the outer layer;
• Fig. 3 a cross section through a non-rotation hybrid rope with such hybrid strands; and
• Fig. 4 a rotation-free hybrid rope using such hybrid strands.

In Fig. 1 schematically a part of a hybrid strand 1 is shown in perspective view. This hybrid strand 1 has a fiber core 2 and around this fiber core 2 around beaten steel wires 3, wherein in Fig. 1 shown only one layer of wires (outer wires) 3 is shown. However, it would be conceivable to provide here (as well as in the following examples) two or more layers of wires, with an outer layer of wires 3, which are cold-worked in the subsequent compression.

Such a cold deformation is shown in FIG Fig. 2 can be seen, it being understood that the wires 3 'around the fiber core 2 around, during compaction, lie flat against each other with their sides and have an approximately trapezoidal cross-section. Overall, the hybrid cable or the hybrid 1 now has a compared to Fig. 1 smaller cross section, with a compression of the (outer) wire layer 4 with the wires 3 '.

In Fig. 3 is a cross section through a hybrid cable 5 is shown, which is not rotation-free in this embodiment, and in the compressed hybrid strands 1 according to Fig. 2 were used. In detail, a core hybrid wire 6 is provided, around which six hybrid strands of an inner strand layer 7 are arranged. Finally, an outer layer 8 with eight hybrid strands 1 (according to FIG Fig. 1 ), wherein a plastic liner 9 supports the outer hybrid strands 1 of this outer layer 8, as is known per se.

For comparison purposes is in Fig. 4 a cross section through a rotation-free hybrid cable 10 is shown, wherein comparable hybrid strands 1, s. Fig. 2 , on the one hand for the core 11 of the rope 10 and on the other hand for the construction of a total of three strand layers 12, 13 and 14 are used. The hybrid strands (1 in Fig. 2 ) also have different diameters to achieve a compact design.

The hybrid rope 10 according to Fig. 4 is rotation-free, with no plastic liner or support body, as with the rope 5 according to Fig. 3 shown are used.

The cross sections according to Fig. 3 and Fig. 4 are examples of possible cable structures, which of course also a variety of other cable construction options are given.

As in particular from Fig. 2 can be seen, are obtained by the compression of the hybrid strand 1 or the cold deformation of the outer wires 3 'more compact cross sections, wherein the total cross section of the hybrid strand 1 is reduced, and wherein the cross sections of the wires 3 from a circular cross-sectional shape to an approximately trapezoidal or circular segment-shaped (Wires 3 ') change. The voids between the wires 3 and 3 'are reduced by the compression process, wherein the relative metallic cross-section and thus the breaking strength of the hybrid strand 1 is substantially increased. Overall, ropes 5 and 10 are made possible in this way, the same breaking force how a conventional steel cable can have a weight that is about 30% lower, or vice versa, with the same weight, it can have a much higher breaking load.

In the following Table 1, values are given for a conventional compacted steel cord and a compacted hybrid cord, according to Fig. 3 , facing each other. Table 1: Rope nominal diameter Compacted steel cable Compacted hybrid rope length weight Specific strength length weight Specific strength 24mm 2.75 kg / m 188 kN / kg 1.95 kg / m 265 kN / kg

The compacted hybrid rope has a 40% higher specific strength compared to a compacted solid steel rope.

A comparison of a compacted and an uncompressed hybrid rope (with the same breaking strength) yields - according to Table 2 - the following nominal rope diameters. Table 2: Hybrid rope compacted Hybrid rope uncompressed Rope nominal Ø Rope nominal Ø 24mm 25, 25mm

For the sake of completeness, it should be stated that the term "specific breaking force" is understood to mean the ratio of the general breaking force to the length weight of a rope.

Claims (6)

1. Hybrid strand (1) having a core (2) and outer wires (3') arranged around said core (2), at least some of the outer wires (3') being compacted, the compacted outer wires (3') comprising a flattened cross-sectional shape, the outer wires (3') consisting of steel and the core (2) being a fibre core, characterised in that a lateral flattened region of a first compacted outer wire (3') opposes a lateral flattened region of an adjacent compacted outer wire (3') at a distance.
2. Hybrid strand according to claim 1, characterised in that the compacted outer wires (3') have an approximately trapezoidal or circular-segment-shaped cross section.
3. Hybrid strand according to either claim 1 or claim 2, characterised in that the distance between the opposing flattened regions is substantially constant at least in portions.
4. Cable (5; 10) having a plurality of hybrid strands (1) according to any of claims 1 to 3.
5. Cable (10) according to claim 4 in the form of a non-twisting cable.
6. Method for producing a hybrid strand (1), steel outer wires (3) being wrapped and compacted around a fibre core (2), the outer wires (3) in the still non-compacted state being in at least near-contact, making contact with one another in a lateral contact region, which is preferably flat, during compaction and at least some of the outer wires (3') comprising a flattened cross-sectional shape in the contact region after compaction, characterised in that the outer wires (3) support one another in an arch-like manner while being compacted and the outer wires (3') are pressed against the fibre core (2) during compaction prior to the arch formation, and spring back by a corresponding amount after compaction, so that the deformed outer wires (3') of the compacted hybrid strand (1) are slightly spaced apart.

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