EP2940206B1 - Hybrid cord - Google Patents

Description

The invention relates generally to a rope of circular cross-section, having a core formed by at least one hybrid strand, the strand core of which is formed of plastic fibers and having at least partially metallic wires disposed therearound, and outer strands disposed about the core ,

Due to their longevity and resistance, steel ropes are well suited for lifting heavy loads. In special applications, for example, for lifting loads from great depths, such as from the deep sea, but the weight of the steel cables is so large that the hereby payload is only comparatively low. For example, a steel cable to lift 300,000kg from 3,000m sea depth would weigh 233,000kg. To lift the desired load, a steel cable with a diameter of about 144mm would be required. However, currently used steel ropes with a diameter of 128mm could only carry about 207,000kg from the aforementioned depth.

As an alternative to steel cables, hybrid cables are known which generally have a fiber core surrounded by steel strands. However, the steel strands and the core have different elongation properties under load and therefore bear the load unevenly. This is particularly disadvantageous in a non-rotating rope, since comparatively high loads are essentially borne by the steel strands wound around the core and the resulting torque of the rope is not compensated by the opposite, lower torque of the fiber core.

In the US Pat. No. 3,075,344 a hybrid rope is described which has identically constructed core and outer strands, each with a resilient filament core and surrounding wires.

From the DE 36 31 211 A1 is a low-leno or -lose wire rope known in which the outside around a hybrid rope core around a single layer of flat strands is arranged.

The WO 2012/087315 A1 discloses an elevator rope with a non-load-bearing Core of elastomeric plastic surrounded by outer wires; This core strand is in turn surrounded by outer wire strands.

A method for producing smooth-surfaced wire rope is known in the DE 134 470 C described; this flat or oval outer strands are stranded around a core, which may consist of wires or a hemp soul.

A wire rope with an independent wire rope core is further from the US Pat. No. 5,946,898 known. The core wire rope is formed here of several strands, each with a fiber core and stranded wires on it.

Further, the WO 80/02572 A1 a steel cord for vehicle tires, which consists of a core strand and outer strands, wherein outer steel wires enclose a non-metallic core.

From the EP 2 573 257 A1 or the corresponding WO 2011/145224 A1 is a hybrid rope with a highly durable core of a fiber material and the core surrounding strands emerge, which also contain in its interior a core of plastic fibers.

The US 5,651,245 discloses a cable having a multi-strand core, preferably entirely of metal. The outer strands surrounding the core in turn have a core of plastic, eg thermoplastic, surrounded by steel wires.

The US 6,563,054 B1 relates to a cable having a core of parallel synthetic fibers surrounded by an annular layer of radially compressible thermoplastic material; Around this thermoplastic layer are arranged outer strands which are made entirely of metal or may have a core of synthetic fibers surrounded by metal strands.

The WO 2012/009604 A2 describes a hybrid cable with a core of synthetic fibers around which strands are arranged, which in turn have a core bundle of synthetic fibers surrounded by metal strands.

The DE 600 15 771 T2 relates to a flat tension member, so band, for lifting an elevator car, with a plurality of load bearing elements embedded in a sheath. The load bearing members comprise steel material and organic fibers which are intended to divide the load between these load bearing members. This rope has no circular cross-section and is formed in comparison to the aforementioned rope for other applications.

The known hybrid cables have a fiber core surrounded by metal or metal-plastic strands, whereby the abovementioned disadvantages resulting from the different expansion properties are established or the hybrid cables are too heavy due to a metal core. In addition, hybrid cables having plastic strands disposed about a core often have too low a friction coefficient for winding and generally do not have the required strength.

The object of the invention is to provide a rope in the form of a hybrid rope which avoids or reduces the disadvantages known from the prior art. The rope should in particular compared with steel cables for lifting an equally heavy load have a much lower weight. In addition, it should have a long service life and be easy or inexpensive to produce.

The rope of the invention having a circular cross-section, having a core formed by at least one hybrid strand, the strand core of which is formed of plastic fibers and arranged around at least partially metallic wires, and outer strands disposed around the core, is characterized characterized in that at least one outer strand is formed with a core of plastic fibers, around which core at least partially metallic wires are arranged, wherein the rope over the rope cross section has substantially the same elongation properties having.

The core of the present rope is thus formed by one or more hybrid strands. This hybrid strand (s) in turn has or possess a core of plastic fibers around which metallic wires, optionally also additional non-metallic wires are arranged. If the core contains a plurality of hybrid strands, these may have mutually different proportions of wires made of non-metallic material, for example plastic, up to versions with exclusively metallic wires. The core of the rope can thus be made particularly stable compared to cores, which consist only of plastic fibers. On the other hand, the core of the rope has a low weight compared to cores of steel strands, since the core of the at least one hybrid strand is made of plastic. Although the core of the rope is formed by several of the described hybrid strands, minor modifications, for example, by incorporating fewer plastic or metal strands, if these do not appreciably affect the advantageous properties of the rope with a core of hybrid strands, are possible. The cable according to the invention has essentially the same elongation properties over the rope cross-section.

According to the invention, moreover, each of the outer strands is formed with a core of plastic fibers around which core at least partially metallic wires are arranged. In addition to the metallic wires, non-metallic wires, for example plastic wires, may be arranged around the core, wherein different outer strands may have different proportions of non-metallic wires. By a suitable choice of the number of wires can be advantageously influenced on the weight of the outer strands. Thus, by a higher number of thinner metal wires, the proportion of metal compared to that of plastic in the core of the outer strand and thus the weight of the strand is reduced while still having a high strength. Also, the optional provided plastic wires around the core of the outer strand reduce the weight of the outer strand.

If an intermediate layer of plastic is arranged between the wires and the core of at least one hybrid strand, the wires can rest stably on the intermediate layer. This plastic liner protects the fibers in the core of the hybrid strand (s) from mechanical stress from the outer wires, thus increasing the life of the hybrid cord. The intermediate layer preferably comprises threads made of plastic, in particular polyester, aramid, liquid-crystalline polyester, polyoxadiazobenzimidazole or highly modular polyethylene; Such threads have a high strength and high dimensional stability. Their low extensibility also contributes to the maintenance of the cross-sectional shape of the threads.

It is particularly advantageous if the intermediate layer comprises an inner layer of untwisted threads and a surrounding outer layer of twisted threads or at least one plastic film having. Here, the inner layer reduces the abrasion between the wires and the core, while the outer layer provides a stable support for the wires.

In order to use the largest possible proportion of the cross section of the cable core for the hybrid strands, the core is advantageously formed by a plurality of hybrid strands with mutually different diameters. For example, smaller diameter hybrid strands may be provided in the spaces between larger diameter hybrid strands. In this way, particularly heavy-duty ropes can be formed with overall large diameters of, for example greater than 100mm, in particular of 128mm.

In order for the respective core to have the highest possible strength with low weight and low elongation at break, it is provided that the synthetic fibers of the core of the at least one hybrid strand and / or optionally of the core of the outer strands comprise aramid, liquid-crystalline polyester, polyoxadiazobenzimidazole, highly modular polyethylene or carbon. Of course, different cores may also have different materials.

It is particularly advantageous if, in order to obtain a rotation-free cable, the outer strands are stranded with a different direction of rotation relative to the at least one hybrid strand. Since strands wound around a core of a rope can cause rope rotation under stress of the rope, when the outer strands are wound in a direction around the core of the rope and the wires of the hybrid strand of the core are wound in the opposite direction that compensates for the tendency for rotation caused by the outer strands and the wires of the hybrid strand. When the core of the cable is formed by a plurality of hybrid strands, the wires of all or at least a portion of the hybrid strands may be oppositely stranded to the outer strands. Likewise, the hybrid strands can be stranded or twisted together even in the opposite direction to the outer strands.

According to another embodiment of the invention is between the outer strands and the at least one hybrid strand arranged an intermediate layer of plastic. As a result, the transverse pressure stability of the hybrid strands is increased, whereby they maintain their round cross-section in the rope. Without this interlayer, the hybrid strands could be ovally pressed due to the transverse pressures in the rope, and the wires from adjacent strands could come into contact. As a result of the permanent relative movement, this contact can lead to internal wear and thus to a shorter service life of the cable. These disadvantages are avoided by the intermediate layer of plastic.

Advantageously, the plastic of the intermediate layer is a thermoplastic, in particular polyethylene or polypropylene. In contrast to polyamide, these plastics are hydrophobic and do not absorb moisture when using the rope in the water.

It is particularly favorable if at least between two adjacent outer strands a support element is arranged, against which the outer strands rest. Preferably, such a support element is arranged between all pairs of adjacent outer strands.

With regard to the spacing of adjacent strands or their concerns on the support element, it is also advantageous if the support element has a circular, elliptical or substantially trapezoidal cross-sectional profile. Circular or elliptical support elements can be arranged in a simple manner as the strands themselves between the strands, while trapezoidal support elements also have the advantage that the strands can rest on the oblique side walls of the trapezium particularly stable.

In order to increase the load capacity of the rope further, it can also be provided that the outer strands are arranged in several concentric layers around the core. The strands may in this case have the same or different diameters.

• Fig. 1 eine Querschnittsansicht eines Seils gemäß der Erfindung, mit einem Kern aus Hybridlitzen, um welchen äußere Litzen angeordnet sind;
• Fig. 2 eine Querschnittsansicht einer Litze des Seils aus Fig. 1; und
• Fig. 3 eine Querschnittsansicht eines Seils gemäß der Erfindung, mit in mehreren konzentrischen Lagen um den Kern angeordneten äußeren Litzen.

The invention will be described below with reference to preferred, not restricting embodiments with reference to the drawings even further explained. Show it:

• Fig. 1 a cross-sectional view of a rope according to the invention, with a core of hybrid strands, around which outer strands are arranged;
• Fig. 2 a cross-sectional view of a strand of the rope Fig. 1 ; and
• Fig. 3 a cross-sectional view of a rope according to the invention, arranged in several concentric layers around the core outer strands.

Fig. 1 shows a rope 1 with a core 2, around which outer strands 3 are arranged. The core 2 is in this case formed by at least one hybrid strand 4, in the illustrated example by 19 hybrid strands 4, the core 5 (each) is formed of plastic fibers. Around this core 5 around wires 6 are arranged. At least a portion of the wires 6 is made of metal, so that wires 6 made of other materials, which have a sufficient strength for the application of the rope 1, can run around the core 5.

The outer strands 3 are also formed with a core 7 made of plastic fibers around which wires 8 are arranged. At least a portion of the wires 8 is made of metal, so that wires 8 made of other materials, which have a sufficient strength for the application of the rope 1, around the core 7 of the outer strands 3 can run.

According to the example in Fig. 1 in which the hybrid strands 4 are arranged in a Warrington construction, the diameters of the hybrid strands 4 may be different, so that the space available for the core 2 is filled as efficiently as possible with hybrid strands 4. Together with the 16 outer strands 3 results in a rope 1 of 35 hybrid strands 3, 4, wherein, without this being apparent from the illustration, advantageously the outer strands 3 are stranded with a different direction of rotation to the hybrid strands 4. Between the outer strands 3 and The hybrid strands 4 of the core 2 also has an intermediate layer 13 made of plastic. Advantageously, a substantially trapezoidal support element 14 is arranged between adjacent outer strands 3, against which the outer strands 3 abut. Although for clarity in Fig. 1 only one support element 14 is shown, it is favorable, although not absolutely necessary, to provide support elements 14 between all adjacent outer strands 3.

In Fig. 2 a strand is shown in cross-section, which likewise represents a hybrid strand 4 of the rope core 2 or an outer strand 3 of the rope 1. Around the core 5 of the hybrid strand 4 or around the core 7 of the outer strand 3, the wires 6 and 8 are arranged, wherein between the wires 6 and the core 5 and between the wires 8 and the core 7, an intermediate layer 9 or 10 is arranged from plastic. The intermediate layer 9 or 10 preferably has an inner layer 11 of untwisted threads and a surrounding outer layer 12 of twisted threads or at least one plastic film on.

In Fig. 3 Another exemplary embodiment of a rope 1 is shown which, in order to withstand higher tensile stresses, has two concentric layers of outer strands 3 around the core 2. In an embodiment of the rope 1, not shown, more than two concentric layers of outer strands 3 may be arranged around the core 2.

As is apparent from the following Table 1, the rope 1 of the invention allows due to its design lifting heavy loads as a steel rope of the same diameter or, in order to lift the same heavy loads, the diameter of the rope 1 according to the invention be smaller than that of a steel cable. <u> Table 1 </ u> steel cable Rope according to the invention Seawater depth (m) 3000 3000 Object weight (kg) 300000 300000 Rope weight in seawater (kg) 233000 82,000 Lifting total weight (kg) 533000 382000 Rope breaking force (kg) 1559000 1261000 safety factor 3 3.3 Rope diameter (mm) 144 128

In order to lift a 300,000 kg object out of a depth of 3000 m, a rope 1 according to the invention with a diameter of 128 mm can thus be used instead of a steel cable with a diameter of 144 mm. This is a decisive advantage, in particular, if a steel cable suitable for lifting the object from a certain depth can not be produced technically or only with great difficulty, or if the use of such a steel cable causes particularly high costs.

In the case of the rope according to the invention, load-bearing synthetic fibers, which have a lower weight compared to steel, thus replace part of the steel wires. These are high-strength synthetic fibers that can take over significant load fractions.

Examples of plastic fibers known per se or their (known) high strength values with regard to use in the present rope are given in Table 2 below: <u> Table 2 </ u> material Designation - Type titres cN / dtex gpa aramid technora T200W 23,95 aramid technora T200 24 aramid technora T221 1670 24.01 aramid Twaron 2200 850 20.35 aramid Twaron 1111 420 21.4 Liquid crystalline polyester Vectran HAT830 14.2 Liquid crystalline polyester Vectran HS1500 2.8 Highly modular polyethylene Dyneema SK38 6600 16.5 1.6 Highly modular polyethylene Dyneema SK62 2640 28.6 2.8 Highly modular polyethylene Dyneema SK65 880 30.8 3 Highly modular polyethylene Dyneema SK75 2640 33.5 3.3 Highly modular polyethylene Dyneema SK75 1760 35.1 3.4 Highly modular polyethylene Dyneema SK78 1760 35.1 3.4 Highly modular polyethylene Spectra 900 6222 25.5 2.18 Highly modular polyethylene Spectra 1000 2888 2.91 Highly modular polyethylene Spectra 2000 200 3.25 Karbon carbon fiber HAS 3.53 Karbon carbon fiber UMS 4.56 Polyoxadiazobenzimidazol Zylon all types 35

Claims (12)

1. Cable (1) having a circular cross section, comprising a core (2) formed by at least one hybrid strand (4), the strand core (5) of which hybrid strand is made of plastics fibres and around which at least partially metal wires (6) are arranged, and comprising outer strands (3) arranged around the core (2), characterised in that all the outer strands (3) are formed having a core (7) made of plastics fibres, around which core (7) at least partially metal wires (8) are arranged, the cable (1) having substantially the same expansion properties over the cable cross section.
2. Cable (1) according to claim 1, characterised in that an intermediate layer (9) made of plastics material is arranged between the wires (6) and the core (5) of at least one hybrid strand (4).
3. Cable (1) according to claim 2, characterised in that the intermediate layer (9) comprises threads made of plastics material, in particular polyester, aramid, liquid-crystalline polyester, polyoxadiazobenzimidazole or high-modulus polyethylene.
4. Cable (1) according to claim 2 or claim 3, characterised in that the intermediate layer (9) comprises an inner layer (11) made of untwisted threads and an outer layer (12) made of twisted threads or at least one plastics film, which outer layer surrounds said inner layer.
5. Cable (1) according to any of claims 1 to 4, characterised in that the core (2) is formed by a plurality of hybrid strands (4) having mutually different diameters.
6. Cable (1) according to any of claims 1 to 5, characterised in that the plastics fibres of the core (5) of the at least one hybrid strand (4) and/or optionally of the core (7) of the outer strands (3) comprise aramid, liquid-crystalline polyester, polyoxadiazobenzimidazole, high-modulus polyethylene, or carbon.
7. Cable (1) according to any of claims 1 to 6, characterised in that the outer strands (3) are stranded with a direction of rotation that is different to that of the at least one hybrid strand (4).
8. Cable (1) according to any of claims 1 to 7, characterised in that an intermediate layer (13) made of plastics material is arranged between the outer strands (3) and the at least one hybrid strand (4).
9. Cable (1) according to claim 8, characterised in that the plastics material of the intermediate layer (13) is a thermoplastic material, in particular polyethylene or polypropylene.
10. Cable (1) according to any of claims 1 to 9, characterised in that a support element (14) is arranged at least between two adjacent outer strands (3), against which support element the outer strands (3) rest.
11. Cable (1) according to claim 10, characterised in that the support element (14) comprises a circular, elliptical or substantially trapezoidal cross-sectional profile.
12. Cable (1) according to any of claims 1 to 11, characterised in that the outer strands (3) are arranged in a plurality of concentric layers around the core (2).

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