CA1054465A - Wire rope with load-carrying fiber elements - Google Patents

Abstract

WIRE ROPE WITH LOAD-CARRYING FIBER ELEMENTS

Abstract of the Disclosure Wire ropes with load-carrying fiber elements are disclosed. The fiber elements are composed high modulus organic materials whereby the fibers can perform the usual function of fibers with respect to lubri-cation, weight reduction and the like while also acting as load-bearing elements. The preferred material is an aromatic polyamide.

Description

~05~65 The present invention relates to steel wire ropes having load-carrying fiber elements therein.
Steel wire ropes are very well-known in the art. They consist of a number of major strands helically wound about ,Q core. Each of the major strands and the core are made up of a number of steel wires, which are also helically wound in each ..:
~- major strand.
,; 10 There have in the past been used fibers or fiber yarns in such steel wire ropes, frequently - in the core and to a lesser degree as a component of the major strands. Typical of these fibers are ~atural fibers such as sisal, manila, jute, hemp, - ~ 1 cotton and the Iike. Synthetic fibers have also been used and typical of these are propylene, nylon (usually --; nylon 6 or nylon 6,6), polyesters, polyvinyl chloride and other thermoplastic or thermoset materials. The primary function of these fibers has been to carry materials such as lubricants to prevent excessive abrasion between adjacent wire strands or chemicals .~. . .
to reduce the moisture which would otherwise cause ~ . .
corrosion of the wire strands. The use of fiber materials also increases the flexibility of the wire :.
rope. Where the core is made of fiber, it also must - ser~e the function of supporting the cross-sectional cr~sh resis~ance of the rope.
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- 1~5~465 The disadvantage to the known fiber materials used in wire ropes is that they are not strong enough compared to the steel wire to be load-bearing. As a result of this, the ; inclusion of known fibers has resulted in an overall weakening of the wire rope and there has had to be a trade of the lubricating, water resistance and flexibility of the rope as : compared to the strength required.
In accordance with the present invention, it has been discovered that certain fiber materials can be used in steel wires which will give all of the advantages of conventionally used fibers but will additionally add load-bearing strength to the complete structure. The fibers are composed of a high ~-;; modulus organic material.
- More specifically, the fibers which have been found '.! ,_ useful in the present invention are fibers made of HMO materials.
The acronym HMO stands for High Modulus Organic and refers to filaments or fibers of synthetic polymers having a high load . at a specified elongation. These fibers and their manufacture are described in Journal of Macromolecular Science A 7 (1973) at pages 1 - 348.
Fibers made of homo- or copolymers of aramids, aromatic polyamide hydrazides and fully aromatic pOlyestersr have been found suitable, with the aramids being preferred.
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~ ' ' . ; " . ' ' ' ' .' ' ~ .,. ' ' ~ '' `. ' ,, ' li 544~5 ; -Typical of the aromatic polyamide hydrazides useful in the present invention are polymers of p-amino-:- benzhydrazide, and terephthaloyl dichloride and copolymers .,, . :
of p-phenylene diamine, terephthaloyl dihydrazide and/or p-aminobenzhydrazide. Typical of the fully aromatic polyesters are homo- or copolyesters made up of tere-- phtalic acid groups and 1,4-dihydroxybenzene groups, which may be substituted with one or more halogen atoms .-: and/or alkyl groups, as desired.
10In accordance with the present invention, aromatic polyamide fibers are preferred and such fibers - are entirely or substantially composed of repeating ::
units haYing the following structural formula:
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- C - Al C
O O ' j:
. and/or . - N - A2- N -; H H
and/or ;
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; ~0 - C - A3- N -O H
wherein Al, A2 and A3 are the same or different divalent rigid groups which contain one or more aromatic rings, ..in which there may occur a heterocyclic ring, and of ~which rigid groups the chain-extending bonds are disposed . ., ._~in the para-position or are arranged parallel and op-~positely directed. Examples of such groups are 1,4-'.~:` :'- .. -'.-. . ~ . .
~ _4-.~ ..

. ~5~;5 phenylene, 4,4'biphenylene, 1,5-naphthylene and 2,6-naphthylene. The groups may contain substituents, as ; for exa~ple, halogens, alkyl groups or the like.
The aramid COmpositions may, if desired, contain up to about 35 mole percent of other groups such as m-phenylene groups, non-rigid groups such as . . .
~ alkyl groups or ether urea or ester groups.

- Typical examples of aramids, suitable for ~ .
- use in the present invention are poly-p-benzamide, 10 poly-p-phenylene terephthalamide and their copolymers.

In accordance with the most preferred embodiment of - the present invention, the aramid fiber is poly-p-pheny-leneterephthalamide.
When fibers according to the present invention are used in steel wire ropes, it has been found that the t following advantages can be achieved:
a) The same breaking load as a conventionaL
wire rope can be achieved with substantially less weight. Alternativelyl a considerably higher breaking load can ~e achieved without an appreciable increase ~ in welght. For example, the breaking load can be ::.; . .
-. increased by 40-100% with an overall weight increase ` of only 3-5%.
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b) Wire ropes with good breaking strength can ~- be made considerably more flexible thereby per~itting ; .
- - the use of smaller winch drums with a corresponding saving of space.
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-: 1~54465 ; c) The production of steel wire ropes can be considerably ~implified since a lower number of wires can be used to achieve the same load carrying capa-bility as higher number steel wire ropes having con-ventional fiber materials therein.
d) Particular advantage is achieved in anchor lines for off-shore drilling rigs, ships or the like, since the breaking strength of the rope can be sub-stantially improved without the need for an increase in weight.
` In the accompanying drawing, there is shown a cross-section of a standard steel wire rope 10 comprising ~' major strands 12 helically wound about a core 14. Each of the major strands 12 comprises a number of wire strands ~~ 16 of varying diameter, said wire strands being helically wound in each major strand. Similarly, the core 14 com-; prises a number of major strands 18, each made up of steel ~ . .
wires, with the major strands bein8 helically wound about their own core 20.
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~ 20 In the wire rope as shown, each major strand :~ consists of 36 steel wires and the overall dimension of ,_ , .
each major strand is about 4.5 mm. The steel wire core - had an approximate weight of 0.7946 kg/m and the breaking .~ - 2 . . strength of the wire rope according to the 160 kp/m - . .
`- classification was 11,200 kp.
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1t35~465 . .
~ For comparison purposes, a polypropylene core ~ .~
`~; was substituted for the teel wire core. The polypro-pylene core had a weight of only 0.7032 kg/m which re-sulted in an overall weight reduction. Ho~ever, there :: .
was also a significant decrease in strength in the ` breaking strength by the 160 kp/m classificatlon, which was only 10,300 kp.

- In accordance with the present invention, - the wire core was substituted by an aramid fiber core, specifically poly-p-phenyleneterephthalamide. This - core had a weight of only 0.6991 kg/m, ~even less than - that of the polypropylene core. However, the breaking . .
.` s~rength according to the 160 kp/m2 classification was increased to 12,500 kp, a breaking strength even higher :~.
I than that achieved with the steel core. In addition, the wire rope made with the aramid core accord~ng to ~- the present invention ~as found to be considerably more flexible than the wire rope with the steel wire core ... .
and furthermore, it could include materials such as ~` 20 lubricants and impregnated water-resisting agents whereas ~ the same in not true of the rope with the standard s~eel '.r':.: wire core.

-: It will be understood that the claims are intended to cover all changes and modifications of the preferred ~mbodiments of the invention, herein chosen for the purpose of illustration which do not constitute `~ departures from the spirlt and scope of the invention.
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Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINE AS FOLLOWS:

1. In a wire rope comprising a plurality of major strands helically wound about a core, each said major strand comprising a plurality of steel wires and said wire rope including fibers therein, the improvement comprising said fibers being composed of a high modulus organic material.

2. The wire rope of claim 1 wherein the high modulus organic material is selected from the group consisting of aromatic polyaramids, aromatic polyamide hydrazides and fully aromatic polyesters.

3. The wire rope of claim 2 wherein the high modulus organic fiber is composed of a material selected from the group consisting of p-aminobenzhydrazide, and terephthaloyl dichloride and copolymers of p-phenylene diamine, terephthaloyl dichloride and terephthaloyl dihydrazide and/or p-aminobenz-hydrazide and homo- or copolyesters made up of terephthalic acid groups and 1,4-dihydroxybenzene groups.

4. The wire rope of claim 1 wherein the high modulus organic fibers are composed of units having the structural formula:
and/or and/or wherein A1, A2 and A3 are the same or different divalent rigid groups which contain one or more aromatic rings, in which there may occur a heterocyclic ring, and of which rigid groups the chain-extending bonds are disposed in the para-position or are arranged parallel and oppositely directed.

5. The wire rope of claim 1 wherein the high modulus organic fibers are composed of poly-p-phenylene-terephthalamide.

6. The wire rope of claim 1 wherein the core is of the high modulus organic fibers.