Flexible elongate members

DESCRIPTION Technical Field

The present invention relates to flexible elongate members such as ropes, cables, hawsers, lines, cords, strings and the like, and in particular to flexible elongate members that are highly visible.

Background Art

JP 03267408 describes a rope in which a retro-reflective strand is twisted together with two other strands to form a conventional rope of three-ply twisted construction. The retro-reflective strand is therefore an integral part of the rope and its physical properties must be taken into account when determining the strength, rigidity and durability of the rope as a whole. The fact that the retro-reflective strand is twisted together with the other two strands during the manufacturing process also places strict limitations on its size because the actual process of forming a twisted rope can only be carried out if all the individual strands have substantially the same diameter. For this reason, the retro-reflective strand of JP 03267408 is initially formed from a base strand having the same diameter as the other two strands. The base strand is then covered with a thin tape to which light-reflecting beads are subsequently added.

Summary of the Invention

The present invention provides a flexible elongate member (which may be commonly referred to as a rope, cable, hawser, line, cord, string or the like) comprising an inner flexible elongate member of twisted construction having two or more strands, and at least one outer strand that is retro-reflective and/or fluorescent and which is twisted around the outside of the inner flexible elongate member such that it lies in a helical channel between two adjacent strands of the inner flexible elongate member but does not form an integral part of the inner flexible elongate member.

It will be readily appreciated that the inner flexible elongate member is formed by twisting the two or more separate strands together in the same direction.

Although the term "strand" is used to describe the individual flexible elongate elements (or ply) from which the inner flexible elongate member is constructed, and the individual flexible elongate element that is twisted around the outside of the inner flexible elongate member, it will be readily appreciated that these individual flexible elongate elements may also be commonly referred to as yarns, tapes, threads, fibres, wires and the like. The strands of the inner flexible elongate member can be formed of any suitable natural or synthetic material such as cotton, acrylic, nylon, polyester, polypropylene, manila, sisal or metal, for example. The choice of material for the strands of the inner flexible elongate member will depend on the intended use of the final product. One or more of the strands can be dyed or otherwise coloured a bright or distinctive colour to make the flexible elongate member more visible during the day when the at least one retro-reflective and/or fluorescent outer strand may not be as effective because of the reduction in contrast between the light that is retro-reflected or emitted and the background environment. The individual strands of the inner flexible elongate member can be dyed or otherwise coloured different, optionally contrasting, colours to give the flexible elongate member a distinctive multi-coloured appearance.

In the case where the outer strand is retro-reflective it means that any light that is incident on the flexible elongate member will be principally returned in the direction from which it came. This means that the flexible elongate member is particularly useful for roadside applications during the night or in periods of low visibility because any light from the headlights of a passing vehicle will be directed back towards the driver making the flexible elongate member highly visible from a distance. A suitable retro-reflective material for the outer strand is a flat elongate tape supplied by 3 M Company under the registered trade mark "Scotchlite" (high visibility product number 8910). The outer strand can also be covered in a retro-reflective coating. For example, if the strands of the inner flexible elongate member are made of metal then the outer strand can also be made of metal that is covered with a suitable retro-

reflective paint or other retro-reflective coating. The retro-reflective coating may optionally include tiny glass beads or micro-prisms in a suitable adhesive or binder.

In another case the outer strand is fluorescent and can be made of a fluorescent material, covered in a fluorescent coating or dyed with a fluorescent paint or dye such that it absorbs and emits light or radiation. A fluorescent outer strand can provide a flexible elongate member having improved visibility during the day when the fluorescent material, coating, paint or dye is activated by ultraviolet radiation from the sun.

The outer strand can be both retro-reflective and fluorescent.

The flexible elongate member is particularly useful for a variety of applications where its high visibility arising from its retro-reflective and/or fluorescent properties would improve safety. For example, the flexible elongate member can be strung between roadside cones to provide a highly visible boundary around or alongside areas of road construction, a crash site or a vehicle awaiting breakdown assistance. It can also be used as a dog lead or horse harness, a mooring rope or tow rope for marine vessels, or for lifting or hauling in the construction industry. In addition to safety applications, the flexible elongate member can be used for purely decorative purposes. For example, the flexible elongate member can be used as a guy rope for illuminated tents and marquees or placed around the edge of a roadside display board.

Unlike planar materials such as retro-reflective or fluorescent panels which can only reflect or absorb and emit radiation coming from a narrow range of angles, the fact that the outer strand is twisted around the outside of the inner flexible elongate member with a helical construction means that it has high visibility from all directions.

Further outer strands can be twisted around the outside of the inner flexible elongate member. In this case, the outer strands are preferably arranged so that they do not cross over each other but run parallel with each other around the outside of the inner

flexible elongate member. This can be achieved by twisting the outer strands around the outside of the inner flexible elongate member such that they all lie in different helical channels between two different adjacent strands of the inner flexible elongate member. For example, if the inner flexible elongate member has three strands then it will be readily appreciated that up to three different outer strands can be twisted around it to run in parallel. One of the outer strands will lie in the helical channel between the first and second strands of the inner flexible elongate member, another of the outer strands will lie in the helical channel between the second and third strands of the inner flexible elongate member, and yet another of the outer strands will lie in the helical channel between the third and first strands of the inner flexible elongate member. Increasing the number of strands twisted together to form the inner flexible elongate member will increase the number of outer strands that can be twisted around the inner flexible elongate member in a parallel manner.

The outer strands can be made of different materials and have different properties. For example, one of the outer strands can be retro-reflective and one of the outer strands can be made of a fluorescent material. Another of the outer strands can be made of a material that is neither retro-reflective nor fluorescent but simply dyed or otherwise coloured to have a contrasting colour to the colour of the strands of the inner flexible elongate member.

The outer strand does not form an integral part of the inner flexible elongate member and the physical properties of the inner flexible elongate member such as strength, flexibility and durability remain unchanged. This means that there is greater freedom of the choice of the size and material for the outer strand. However, the twisted construction of the inner flexible elongate member means that the outer strand is effectively constrained between the adjacent strands of the inner flexible elongate member which prevents the outer strand from moving freely along the outside surface and becoming loose. This is important because it means that the outer strand is an integral part of the flexible elongate member as a whole. The flexible elongate member can therefore be used for certain applications where strength or durability is important and where it would not be acceptable for the outer strand to come loose and

snag or catch. For the best results, the diameter of the outer strand (or its width in the case where it is a flat elongate tape) is less than the diameter of the individual strands that are twisted together to form the inner flexible elongate member. This way, the outer strand will sit securely within the helical channel or groove between the larger adjacent strands of the inner flexible elongate member. For example, for an inner flexible elongate member of 25 mm diameter, the diameter or width of the outer strand can be about 5 mm.

The flexible elongate member can be used to form, or be incorporated into, a fabric material by any suitable process such as weaving or knitting, for example.

The outer strand can be twisted around a completed length of inner flexible elongate member or can be applied as part of the manufacturing process of the inner flexible elongate member.

The present invention further provides a method of making a flexible elongate member comprising the steps of: forming an inner flexible elongate member of twisted construction by twisting together two or more strands; and twisting at least one outer strand around the outside of the inner flexible elongate member such that it lies in a helical channel between two adjacent strands of the inner flexible elongate member but does not form an integral part of the inner flexible elongate member.

The outer strand is preferably retro-reflective and/or fluorescent for the reasons described above.

The flexible elongate member can be made using a traditional method where a ropewalk is used to twist together the strands of the inner flexible member. One end of the ropewalk includes a number of rotating driven anchors, one for each of the strands, mounted to a fixed support and the other end includes a common anchor that can rotate freely. Each strand is formed from a number of individual yarns or threads and is attached or secured between its associated rotating anchor and the common anchor. A dolly is located between the support and the common anchor and includes

a number of spaced (preferably equally spaced) grooves on its outer surface for receiving the strands. The dolly also includes a mechanism for feeding the outer strand (that is preferably retro-reflective and/or fluorescent for the reasons described above) around the outside of the inner flexible elongate member. If the inner flexible elongate member has three strands then the support will include three rotating driven anchors and the dolly will have three spaced grooves, for example. If two or more outer strands are to be twisted around the outside of the inner flexible elongate member then the dolly will have a separate mechanism for feeding each outer strand.

The dolly is initially located near the common anchor. The dolly is preferably of cone-shaped construction with its narrow end facing away from the support so that the strands of the inner flexible elongate member are separated by the grooves along the axial length of the dolly but come together at the narrow end. The mechanism for feeding and guiding the outer strand can take the form of an eyelet through which the outer strand can be fed or drawn from a rotatable drum that is mounted to the dolly. The free end of the outer strand is secured to one of the strands of the inner flexible elongate member or to the common anchor. The free end of the outer strand can be secured to the strand by tucking it between the individual yarns or threads that together make up the strand, for example. The free end of the outer strand can be secured to the strand either before the individual yarns or threads are twisted together, or after they have been twisted together but before the dolly is moved towards the driven anchors to twist the strands together to form the inner flexible elongate member.

The individual yarns or threads forming each of the strands of the inner flexible elongate member are twisted together by rotating the driven anchors in the same direction. The driven anchors can be rotated by one or more electric motors or actuations, for example.

As the tension in the strands increases they come together at the narrow end of the dolly and start to twist together. The action of twisting the strands together causes the

common anchor to rotate in the opposite direction and the shortening of the length of the strands causes the common anchor to move towards the support.

At the same time, the dolly is moved manually in a direction towards the driven anchors and as it moves the strands twist together behind it at the narrow end to form the finished inner flexible elongate member. The movement of the dolly automatically causes the outer strand to be fed from the rotatable drum through the eyelet and twisted around the outside of the inner flexible elongate member at the narrow end of the dolly such that it lies in a helical channel between two adjacent strands of the inner flexible elongate member. When the dolly reaches the driven anchors the process is complete and the flexible elongate member can be "hardened" to release any remaining tension in the strands of the inner flexible elongate member. The ends of the flexible elongate member can be tied off or fixed to prevent the strands from coming apart.

The flexible elongate member can also be made on larger scale using a continuous rope making machine that is adapted to provide a feeding mechanism for twisting the outer strand around the outside of the inner flexible elongate member such that is lies in a helical channel between two adjacent strands of the inner flexible elongate member.

Drawings

Figure 1 is a side view of a rope according to a first embodiment of the present invention; Figure 2 is a side view of a rope according to a second embodiment of the present invention; and

Figure 3 is a side view of a rope according to a third embodiment of the present invention.

Figure 1 shows a rope 1 of three-ply twisted construction where three acrylic strands 2a, 2b and 2c are twisted together in the same direction. A flat elongate tape 4 made

of retro-reflective material is twisted around the outside of the rope 1 and lies in the helical channel 6 between two adjacent strands 2a and 2b of the rope.

In Figure 2, a second flat elongate tape 8 made of retro-reflective material is twisted around the outside of the rope 1 and lies in the helical channel between the two adjacent strands 2c and 2a of the rope. The tapes 4 and 8 therefore run parallel around the outside of the rope 1.

In Figure 3, a thin acrylic strand 10 is twisted around the outside of the rope 1 and lies in the helical channel between the two adjacent strands 2b and 2c. The strand 10 has a different contrasting colour to the strands 2a, 2b and 2c of the rope 1. The tapes 4 and 8, and the strand 10, run parallel around the outside of the rope 1.