GB2036825A

GB2036825A - Synthetic Fibre Rope

Info

Publication number: GB2036825A
Application number: GB7940231A
Authority: GB
Original assignee: Drahtseilwerk Saar GmbH
Current assignee: Drahtseilwerk Saar GmbH
Priority date: 1978-12-13
Filing date: 1979-11-21
Publication date: 1980-07-02
Also published as: AT367112B; ATA731279A; LU81965A1; BE880279A; NO793420L; IT7927910A0; BR7908024A; DE2853661C2; NL7908898A; CH643901A5; GB2036825B; ES246896U; FR2468684B1; DE2853661A1; GR74098B; FR2468684A1; IT1126501B; PT70453A; ES246896Y; SE7910232L

Abstract

To provide a rope made of synthetic fibres which is light and flexible and yet is comparable in strength with a wire rope, and which can be used over pulleys of relatively small diameter, use is made of aromatic polyamide fibres, more particularly poly-p- phenyleneterephthalamide. Instead of being twisted, layers 10 and 20 provided around core 1 are parallel laid and thereby have line or band contact between the components of the layers as compared with the crossing point contacts in prior known proposals. <IMAGE>

Description

SPECIFICATION Synthetic Fibre Rope This invention relates to a synthetic fibre rope made of aromatic polyamide, more especially poly-p-phenyleneterephthalamide, having components which are laid or twisted in layers over a core to form the rope.

Aromatic polyamides, more especially poly-p phenyleneterephthalamide which has become known under the name "Kevlar", in comparison with other plastics materials, have an exceptionally high modulus of elasticity. The elastic elongation thereof amounts to only 1.6 times that of steel, whilst in the case of other polyamides, e.g. Nylon, it can be as much as about 25 times. Thus, this material can not only be used as a supporting insert in steel ropes, for instance in accordance with German Offenlegungsschrift No. 27 08 904, or in combination with other metals, e.g. with electric cables of deep-sea or marine ropes, but it can be used alone or in combination with other plastics materials, for example as a crane rope in accordance with German Auslegeschrift No. 24 55 273.

Synthetic fibre ropes based on aromatic polyamides, like textile ropes produced from natural fibres, are also light and flexible, but are comparable in strength with wire ropes.

Mentioned in German Auslegeschrift No. 24 55 273, in addition to high tear strength and low weight, flexibility and high tensile strength for the rope proposed therein, are, furthermore, high useful life, more especially in the case where the rope runs over small rope pulleys, and, considering the long useful life, high abrasion strength and alternating bending strength; to increase the internal abrasion strength when running over small guide pulleys, the strands of the rope are proposed to be impregnated with a plastics material, for example polyurethane.

The problem underlying the invention is to increase further the useful life of a synthetic fibre rope of the kind designated at the introduction hereof.

In accordance with the invention, for this purpose provision is made for the fact that the synthetic fibre rope has, in accordance with a construction which is known for wire ropes, a plurality of layers (or plies) whose components extend parallel to one another from layer to layer.

This measure is based on the recognition and the idea that synthetic fibre ropes made from aromatic polyamides, irrespective of their fibre structure should not, as previously, be produced in the manner of the textile ropemaking and with crossing-over of the strands, but in the parallel type of manufacture, known as a special type of manufacture of wire ropemaking, in order to subject the material to only the least-possible transverse stressings. The parallel run of the superposed or superjacent strands of the different layers provides, between the layers, only linear contact and, therewith, a considerably lower surface pressure than in the case of the punctiform contact which results upon the the crossing-over of the strands.It has previously not been seen or at any rate it has been overlooked that fibres made from aromatic polyamides, unlike other synthetic fibres as well as natural fibres, are particularly sensitive to transverse stressing or pressing to an extent which reduces useful life, unless it is taken into account: skeins made from aromatic polyamide fibres have in the past not only been crossed-over upon the stranding, but even braided, which additionally leads to greater sensitivity to rupture.

In addition to this, aromatic polyamides represent, for ropes in parallel type of manufacture, a particularly advantageous choice of material insofar as they reduce significant, or practically eliminate the difficulty, always present in the case of steel ropes, of compensating for elongation between parallel-stranded strand layers by virtue of their greater elongation. This makes possible, inter alia, a simpler lay length adaptation of the strands of the different layers in such a way that the fibre skeins of superimposed strand layers do not intersect.

Finally, the invention has the advantageous aspect of being able to split a rope up into a larger number of layers without damage, i.e. without creating weak points by overlappings, and thereby of being able to make the rope elements or components thinner, so that the filaments therein are not subjected to very different tensile loadings upon bending. The said elements or components of the rope will, as a rule, be strands laid from fibre skeins. However, they may also themselves already be ropes or fibre skeins, preferably sheathed, in which the fibres, always present in the form of continuous monofils, are laid.

If the elements or components are multi-layer strands, then the fibre skeins therein forming the layers preferably extend likewise parallel to one another from layer to layer, i.e. they are parallel lay strands.

Once again all that which is said above for the parallel type of manufacture of the rope applies hereto. The advantage of the combination of material and parallel-lay is additionally considerably more significant insofar as in the parallel-lay strands no elongation adaptation at all of the layers to one another is possible, while one can additionally undertake certain adaptations in the rope, by different lay lengths of the strands of the various layers.

Also, the fibre skeins laid into strands are preferably themselves laid, but may also be sheathed bunches of parallel fibres. Depending on practical circumstances, especially with relatively thin diameters, braided fibre skeins or fibre skeins consisting of fibre bunches bonded in themselves may be employed. However, braided fibre bunches have undesirable overlappings, and parallel fibre bunches are disadvantageous insofar as the monofils therein are subject to significantly different tensile loadings when subjected to bending. In laid fibre bunches, the monofils can compensate for such different tensile loadings by longitudinal displacement relative to one another; they should to that extent not be bonded, at any rate not in such a way that the mobility relative to one another is impaired.

If the said elements are themselves already laid from strands, then in the strands thereof, if they are multi-layer, the fibre skeins preferably also extend parallel to one another from layer to layer.

If the strands in the component are arranged in several layers, then accordingly the same holds good for this.

In order to reduce still further the surface pressure at the lines of contact, in an advantageous development of the invention the elements or components of the ropes have a smoother surface than would result with a circular cross-section of the fibre skeins or strands forming the elements. In this way, the said line contact becomes continuous, whilst in the case of the normal surface, which is fluted or corrugated as a result of the rounding of the fibre skeins or strands, of the strands or ropes the contact between the elements is afforded only on a point line.

The desired smooth surface can, for example, be provided in that the elements are given a, preferably extruded-on, sheathing having a smooth surface.

However, the fibre structure of the material also allows other arrangements. The fibre skeins need only to be laid somewhat loosely and the strands produced from these fibre skeins somewhat more securely; then the fibre skeins in the strands adapt to one another along with deformation and formation of an extremely tight or compact strand structure in the interior, and on the outside there is formed a rather smooth surface. If the fibre skeins are sheathed bunches of parallel fibres, this all occurs anyway extensively of its own accord.

One can design fibre skeins also, like profile wires, e.g. by nonding as profiles which can be laid into a tight strand and/or a strand having a smooth surface.

If the elements of the rope are themselves already ropes, then the same holds good for the strands of which these ropes consist.

If also the components or elements of the rope are laid loosely in themselves, then the said line contact is broadened into surface contact.

Finally, construction in accordance with the invention, preferably those of less complicated construction, with all their advantages, can in themselves serve as an element of a rope.

Possibly as an element or component of a rope is basically the simple version whose components are fibre skeins and which one can also consider as a strand in which one equates the fibre skein to a wire.

The accompanying drawing illustrates an exemplified embodiment of the rope of the invention.

The figure shows a wire rope, of parallel-type manufacture, made from parallel-lay strands.

The rope comprises a core strand 1, an inner strand layer 10 of five strands 2 and fine smaller monofil strands 3, and an outer strand layer 20, twisted parallel with the inner strand layer 10, of ten identical strands 4.

The core strands 1 are single-layer 1+6 strands. The strands 2 are two-layer 1+6+12 parallellay strands. The monofil strands 3 are lightly-laid parallel monofil bunches. The strands 4 are two-layer parallel-lay strands (Seale strands) +9+9.

The strands 1, 2 and 4 are composed of monofil skeins of poly-pphenyleneterephthalamine, which are twisted loosely in themselves. Upon the stranding, the previously-round monofil skeins have adapted to one another by their cross-sections. In the interiors of the strands, the monofil skeins are largely joined or conjoined (i.e. are in close abutment) without intermediate gaps. The outsides of the outer monofil skeins are flattened.

The strand circumference is accordingly comparatively smooth and displays only small furrows 5 between the individual monofil skeins.

The monofils consist of poly-pphenyleneterephthalamide of "Kevlar 49" quality.

The density of the strands and the parallel type of manufacture of the rope increase the material cross-section and thus reduce the space requirement of the rope on winches, and so forth.

In the rope of the invention, dissimilar monofil skeins and strands can, of course, be combined with one another.

Claims

1. A synthetic fibre rope made of aromatic polyamide, more especially poly-pphenyleneterephthalamide, comprising components laid or twisted in layers over a core to form the rope, characterised in that the synthetic fibre rope has, in accordance with a construction known for wire ropes, a plurality of layers whose components extend parallel to one another from layer to layer.

2. A synthetic fibre rope as claimed in claim 1, characterised in that the said components are strands laid or twisted from fibre skeins.

3. A synthetic fibre rope as claimed in claim 2, characterised in that the fibre skeins in the strands are arranged in a plurality of layers and likewise extend parallel to one another from layer to layer.

4. A synthetic fibre rope as claimed in claim 2 or 3, characterised in that the fibre skeins laid into strands are plaited or laid or are fibre bunches which are sheathed or bonded in themselves.

5. A synthetic fibre rope as claimed in claim 1, characterised in that the said components are ropes laid from strands, in which the fibre skeins are arranged in a plurality of layers and likewise extend parallel to one another from layer to layer.

6. A synthetic fibre rope as claimed in claim 1, characterised in that the said components are laid and/or sheathed fibre skeins.

7. A synthetic fibre rope as claimed in any preceding claim characterised in that the components have a smoother surface than would result with a circular cross-section of the fibre skeins or strands forming the elements.

8. A synthetic fibre rope as claimed in claim 7, characterised in that the fibre skeins or strands are laid loosely in themselves or the fibre skeins are designed as profiles or the elements have smooth-surfaced sheathing.

9. A synthetic fibre rope as claimed in claim 8, wherein the elements have smooth-surfaced sheathing, characterised in that the sheathing is an extruded sheathing.

10. A synthetic fibre rope as claimed in any preceding claim characterised in that the elements are laid loosely in themselves.

11. A synthetic fibre rope as claimed in any preceding claim more especially as claimed in claim 8, characterised in that it is itself an element of a rope.

12. A synthetic fibre rope substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.