GB2498651A

GB2498651A - Protective Sleeve for Wire Rope

Info

Publication number: GB2498651A
Application number: GB1300870.1A
Authority: GB
Inventors: Jagannathan Mohanraj; David Michael Sleightholm
Original assignee: Bridon Ltd
Current assignee: Bridon Ltd
Priority date: 2012-01-23
Filing date: 2013-01-17
Publication date: 2013-07-24
Anticipated expiration: 2033-01-17
Also published as: GB201201194D0; GB201300870D0; GB2498651B

Abstract

A protective sleeve 3b, preferably reaction injection moulded of polyurethane resin, is provided at the location(s) where wear is expected to occur on a wire rope. The level of protection may be enhanced by incorporating reinforcement 3a within the sleeve, on the wire rope before forming the sleeve or as an outer sleeve. The reinforcement may comprise a steel or wire band winding with spaces between the wires into which material of the sleeve may flow when forming the sleeve. The sleeve may comprise an inner and an outer sleeve of different materials or materials with different mechanical properties. The inner sleeve, or reinforcement, may be a different colour to the outer sleeve to provide wear indication. The ends of the sleeve may taper towards the rope (3 , figure 5) or the sleeve may have a thickness which varies along its length such as tapering between its ends. Longer sleeves may be formed by a plurality of successive moulding operations.

Description

Protective Sleeve for Wire Rope

[0001] FIELD OF THE INVENTION

[0002] This invention relates to a system for protecting wire ropes or cables from external mechanical damage in the working environment.

[0003] BACKGROUND OF THE INVENTION

[0004] Wire ropes and cables are used in a wide range of engineering applications.

These applications include, for example, cables that may be used as mooring ropes in shipping, for offshore oil rigs, in bridges and other construction applications, cables for cranes and excavators, and many other applications.

[0005] Generally wire ropes comprise multiple individual strands often wound together helically into a bundle. The size of the ropes, the size of individual strands within a rope, the number of strands to form a rope, the choice of wires for the strands are all design parameters that will be varied depending on the requirements of a particular application. A wire rope may comprise a single bundle of helically wound strands, or multiple bundles of strands may in turn be wound helically together.

[0006] Although such wire ropes are very strong they can be subject to wear. This is particularly the case where the wire rope is subject to repeated motion relative to another pad of the associated machinery. For example, the wire rope may move against a pulley or a guide member which may cause wear and deterioration. In other applications -for example in civil engineering or construction applications -the wire rope may be subject to damage caused by external impact and abrasion from falling rocks, debris and the like. In such cases the damage may be so severe that individual wires or elements within the rope may be deformed, displaced and/or broken [0007] Often such damage is localised to a small section of the wire rope, but nevertheless the entire rope may have to be discarded even though the remainder of the rope may be in good condition and the wire rope is well within its normal working life as would be expected based on calculations of general wear and fatigue criteria. An object of the invention is therefore to provide a means for avoiding such premature discarding of otherwise sound wire ropes.

[0008] SUMMARY OF THE INVENTION

[0009] According to the present invention there is provided a wire rope provided with a wear resistant protective sleeve extending along a discrete section of the wire rope where there is expected to be excessive wear, said sleeve extending circumferentially around the wire rope, and wherein reinforcing means is provided along said discrete section.

[0010] Preferably the reinforcing means comprises a reinforcing element arranged around the wire rope between the wire rope and the protective sleeve. In some embodiments the reinforcing element is helically wound around the wire rope, and spaces are provided between turns of the reinforcing element whereby material forming the protective sleeve may extend into the spaces. For example the reinforcing element may be a steel wire or a steel band.

[0011] In some embodiments of the invention the reinforcing means is provided within the protective sleeve.

[0012] In some embodiments of the invention the sleeve may be a different colour from the reinforcing means.

[0013] In some embodiments of the invention the protective sleeve may comprise two concentric sleeves. The two concentric sleeves may be formed of different materials and/or coloured materials. In some embodiments of the invention one of the sleeves is formed of a steel band or helical wire.

[0014] Preferably the longitudinal ends of the sleeve taper towards the surface of the wire rope.

[0015] Preferably the protective sleeve is formed of a thermosetting resin. When two concentric sleeves are provided both sleeves may be formed of the same thermosetting resin but with different mechanical properties.

[0016] In some embodiments of the invention the thickness of the sleeve varies along the length of the sleeve. For example, the sleeve may be thicker at one end of the sleeve than the other such that the thickness of the sleeve tapers between said ends.

[0017] Preferably the sleeve has a thickness in a radial direction of between 10% and 20% of the diameter of the wire rope.

[0018] In some embodiments of the invention there may be at least two protective sleeves formed along the length of the wire rope.

[0019] According to another aspect of the present invention there is provided apparatus including a wire rope as defined hereinabove wherein in use the wire rope is anticipated to experience wear at at least one discrete section along the length of the wire rope, and wherein the protective sleeve is provided at said at least one section.

[0020] According to another aspect of the present invention there is provided a method for protecting a wire rope used in an apparatus where the wire rope is is anticipated to experience wear at at least one discrete section along the length of the wire rope, wherein a protective sleeve is provided at said at least one section and wherein said wire rope is provided with reinforcing means along said discrete section.

[0021] Preferably the method may further comprise winding a reinforcing element around the wire rope. Preferably the reinforcing element is wound helically around the wire rope leaving spaces between turns of the reinforcing element, and the protective sleeve is formed so as to extend into the spaces. The reinforcing element may be a steel band or a steel wire. The reinforcing means may be provided as part of said sleeve. The sleeve may a different colour from the reinforcing means.

[0022] In some embodiments of the invention the protective sleeve comprises two concentric sleeves. The invention may comprise forming the two concentric sleeves of different colours, and/or of different materials.

[0023] In some embodiments the method comprises forming one of the sleeves of a steel band or helical wire.

[0024] In some embodiments the method comprises providing the longitudinal ends of the sleeve with a taper towards the surface of the wire rope.

[0025] Preferably the method comprises forming the protective sleeve of a thermosetting resin. When there are two concentric sleeves the method may comprise forming the two sleeves of the same thermosetting resin but providing said sleeves with different properties by varying the proportions of reactants and/or additives.

[0026] The method may comprise forming the sleeve with a varying thickness along its length. The method may in particular comprise forming the sleeve so as to taper from one longitudinal end to the other longitudinal end.

[0027] In embodiments of the invention the sleeve may be formed to have a thickness of from 10% to 20% of the diameter of the wire rope.

[0028] In embodiments of the invention the method may comprise forming at least two protective sleeves along the length of the wire rope.

[0029] In some embodiments the sleeve may be formed by a plurality of successive moulding operations.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Some embodiments of the invention will now be described byway of example and with reference to the accompanying drawings, in which:- [0032] Figure 1 is a perspective view of a length of wire rope according to an embodiment of the invention, [0033] Figure 2 is a sectional view through the wire rope of Figure 1 along the line A-A, [0034] Figure 3 is a perspective view of a length of wire rope according to another embodiment of the invention, [0035] Figure 4 is a sectional view through the wire rope of Figure 3 along the line B-B, [0036] Figure 5 shows a side view of a wire rope with a protective sleeve according to an embodiment of the invention, and [0037] Figure 6 is a perspective view of a wire rope according to an embodiment of the invention when attached to an excavator shovel.

[0038] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0039] Referring firstly to Figures 1 and 2 a first embodiment of the invention is shown. Referring in particular to Figure 1 there is shown therein a length of wire rope 1.

The wire rope 1 may take any known form and in particular may comprise a bundle of individual strands 2 that are helically wound together. The number of individual strands, their strength, the choice of metal and other parameters may all be chosen depending on the desired specification for the wire rope. It will be understood that the wire rope 1 may be of any required length and will normally be much longer than is shown in Figure 1.

[0040] Surrounding a section of the wire rope 1 is a protective sleeve 3 which may be formed (as will be discussed in more detail below) from a thermosetting resin. A polyurethane resin with a Shore D hardness in the region of 50-90 is particularly suitable as it is found to offer a good combination of strength, stiffness and impact toughness and wear resistance. As will be discussed in more detail below the protective sleeve 3 is provided at a location along the length of the wire rope 1 where in use localised wear and damage is anticipated to occur. The protective sleeve is not provided along the full length of the wire rope 1 but only at localised areas where such wear and damage may occur.

[0041] The thickness of the sleeve 3 can be selected as any required thickness but, just as one example, a sleeve with an external diameter d of 90mm may be provided on a wire rope with a 76mm external diameter d (Figure 2).

S

[0042] Figures 3 and 4 show an alternative embodiment of the invention in which the protective sleeve 3 is formed of two different concentric sleeves 3a,3b. An advantage of this embodiment is that the two sleeves 3a,3b may be formed of different colours to provide a wear indication. For example, if the inner sleeve 3a is formed of a red S thermoset resin and the outer sleeve 3b is formed of a yellow thermoset resin, then if on a visual inspection of the wire rope 1 red can be seen this is an indication that the outer sleeve 3b is being worn away and the red inner sleeve 3a is becoming visible. This can be an indication that excessive wear is occurring and remedial action can be taken before the wire rope is damaged.

[0043] The protective sleeves may be made of any desired length depending on the intended application but may, for example, be up to several meters long. It is important to note, however, that the protective sleeve(s) is/are provided only at location(s) along the wire rope where excessive wear is expected to occur, and the protective sleeve is not provided along the full length of the wire rope which would needlessly add to the cost and weight of the wire rope. There is no absolute limit to the radial thickness of the sleeve, though in practice it is likely to be between 10% and 20% of the rope diameter.

Sleeves that are too thick may be too stiff, while sleeves that are too thin may not achieve the desired performance. The thickness of the sleeve could also taper from -for example -20% of the rope diameter at one end point of the sleeve to 10% at the other to provide a graduated stiffness.

[0044] In an embodiment of the invention the protective sleeve is formed by casting a sleeve of thermosetting resin, for example by the process of reaction or reinforced reaction injection moulding. The size and shape of a sleeve can be controlled by having one or more split moulds that may be heated and are clamped temporarily around the wire rope in the predetermined location(s) while the metered liquid reactants are injected into the mould and allowed to cure. As indicated above a polyurethane resin with a Shore D hardness in the region of 50-90 is particularly suitable. Other possible materials include, silicone, epoxy, phenolic, polyester, or neoprene.

[0045] In embodiments of the invention where there are two protective sleeves they may be formed of different materials with different properties. For example one of the sleeves such as the inner sleeve may be formed of a material that is harder than the outer sleeve which may be made of a more flexible material. Alternatively the outer sleeve may be formed of harder material. As an alternative to forming the two sleeves of completely different materials, they may be formed from the same thermoset resin but are provided with different mechanical properties by the use of additives and/or by controlling parameters of the moulding process. It will thus be understood that by providing two concentric sleeves either of different materials or of the same basic material but with properties altered, the mechanical properties of the two sleeves can be adjusted to provide a wide range of design options.

[0046] In simple embodiments the moulds will be concentric to the wire rope and parallel to the surface of the wire rope to give a smooth cylindrical sleeve. However, this will result in a step at the end of the sleeve which may be disadvantageous and so the sleeve could be contoured to provide tapering or rounded ends of the sleeve. This is illustrated in Figure 5 which shows a side view of a wire rope 1 provided with a protective sleeve 3 where the sleeve 3 has tapering end portions 3'. The mould sections will preferably be vented to avoid porosity in the casting and may be heated to accelerate the curing (cross-linking) process. This will also enable differences in ambient temperature to be compensated for. The moulds may also be provided with alignment studs (for example these may be in the form of pins, pegs, or packing pieces) to ensure that the rope is properly centred within the mould. These may be retractable to assist in the removal of the rope and sleeving from the moulds. The internal faces of the mould may also be lubricated with a mould release agent to facilitate their removal from the rope after casting. Suitable mould release agents include molybdenum disulphide, PTFE and silicone release agents [0047] In further embodiments of the invention the sections of the wire rope to be protected by a sleeve may be provided with additional reinforcing means either to enhance the stiffness of the wire rope or to improve the damage resistance of the sleeve.

For example the section of the wire rope to be protected may be provided with steel reinforcement in the form of preformed helical steel band(s) or wires that are arranged helically around the wire rope prior to casting of the plastics sleeve. When steel bands are used they may be wrapped around the rope in situ, while when helical wires are provided they may be preformed and then placed in position around the wire rope. Such steel bands or steel wires may be considered to be a second protective sleeve 3a as in Figures 3 and 4. The steel bands may be coated for corrosion prevention and in a colour that contrasts with that of the protective sleeve. The wires or bands may be gapped to allow the plastics sleeve material to flow between them and to key to the underlying rope surface though the gaps should not be so large that the protective properties of the steel band are significantly diminished. A suitable steel band may be 0.5mm thick low carbon steel strapping. While in the abovedescribed embodiments the steel bands or steel wires are provided as the inner sleeve adjacent the wire rope, it may also be possible to provide the steel bands or steel wires as the outer sleeve.

[0048] Additionally the rope surface may be wrapped with a fibre reinforced tape to assist sealing at the ends of the moulds and to inhibit the exudation of lubricant from the rope that might otherwise contaminate the sleeve. The plastics of the tape (but not the fibres) may melt during moulding under the influence of the exotherm of the curing (cross-linking) process. The width of the bands or tape may be selected so that a single wrap can be used but with helical wire reinforcing it is likely that a plurality of members (at least 20) will be required. The surface of the wires or tape and that of the rope may be treated with a primer to enhance adhesion of the cast to the substrate if required.

[0049] In other embodiments of the invention the protective sleeve itself may be provided with reinforcing means such as reinforcing wires or other fibers. Where reinforcing means are provided, whether as part of the protective sleeve or otherwise, the reinforcing means and the protective sleeve may be formed of different coloured materials whereby wear of the protective sleeve may be more easily observed.

[0050] Figure 6 illustrates an embodiment of the invention applied in the context of a wire rope that is used to control an excavator shovel 10. In use two wire ropes 11,12 are connected to the shovel 10 and in particular each wire rope 11,12 is fed around a block 14 and between a number of guide rollers 15 (the block and guide rollers for the rope 12 cannot be seen in the figure as they are on the other side of the shovel 10 but are of the same form). It should be noted that Figure 6 shows the shovel in an unloaded configuration, in use the ropes would extend upwardly and in particular the wire ropes 11,12 tend to contact the radiused surface 16 of the bail of the excavator bucket and in use will move relative to the surface 18 and will be subject to wear and degradation. To prevent this from happening each wire rope 11,12 is provided with two protective sleeves 16,16,17,17' that extend up to the point where the rope enters the block 14 and are at least long enough to protect the ropes 11,12 from wear as they move against the surface 18.

[0051] In another embodiment of the invention a protective sleeve may be used to reinforce an anchor line (rope or strand) at the point of touch down with the sea-bed, where it may be subjected to heavy abrasion. In such an embodiment it may be desirable to protect a greater length of the rope (or strand) than is practical with a single moulding and therefore a number of sleeve sections may be moulded successively along the length of the rope (or strand) in such a way that they abut and seal to one another.

Claims

<claim-text>SCLAIMS: 1. A wire rope provided with a wear resistant protective sleeve extending along a discrete section of the wire rope where there is expected to be excessive wear, said sleeve extending circumferontially around the wire rope, and wherein reinforcing means is provided along said discrete section.</claim-text> <claim-text>2. A wire rope as claimed in claim 1 wherein said reinforcing means comprises a reinforcing element arranged around said wire rope between said wire rope and said protective sleeve.</claim-text> <claim-text>3. A wire rope as claimed in claim 2 wherein said reinforcing element is helically wound around said wire rope, and wherein spaces are provided between turns of said reinforcing element whereby material forming said protective sleeve may extend into said spaces.</claim-text> <claim-text>4. A wire rope as claimed in claim 2 or 3 wherein said reinforcing element is a steel wire or a steel band 5. A wire rope as claimed in claim 1 wherein the reinforcing means is provided within the protective sleeve.6. A wire rope as claimed in any preceding claim wherein the sleeve is a different colour from the reinforcing means.7. A wire rope as claimed in any preceding claim wherein the protective sleeve comprises two concentric sleeves 8. A wire rope as claimed in claim 7 wherein the two concentric sleeves are formed of different coloured materials.9. A wire rope as claimed in claim 7 or claim 8 wherein the two concentric sleeves are formed of different materials.10. A wire rope as claimed in claim 7 wherein one of the sleeves is formed of a steel band or helical wire.11. A wire rope as claimed in any preceding claim wherein the longitudinal ends of the sleeve taper towards the surface of the wire rope.12. A wire rope as claimed in any preceding claim wherein the protective sleeve is formed of a thermosetting resin.13. A wire rope as claimed in claim 12 when dependent on claim 7 wherein both sleeves are formed of the same thermosetting resin but with different mechanical properties 14. A wire rope as claimed in any preceding claim wherein the thickness of the sleeve varies along the length of the sleeve.15. A wire rope as claimed in claim 14 wherein the sleeve is thicker at one end of the sleeve than the other and wherein the thickness of the sleeve tapers between said ends.16. A wire rope as claimed in any preceding claim wherein the sleeve has a thickness in a radial direction of between 10% and 20% of the diameter of the wire rope.17. A wire rope as claimed in any preceding claim comprising at least two protective sleeves formed along the length of the wire rope.18. A wire rope substantially as hereinbefore described with reference to the accompanying drawings.19. Apparatus including a wire rope as claimed in any preceding claim wherein in use the wire rope is anticipated to experience wear at at least one discrete section along the length of the wire rope, and wherein the protective sleeve is provided at said at least one section.20. A method for protecting a wire rope used in an apparatus where the wire rope is is anticipated to experience wear at at least one discrete section along the length of the wire rope, wherein a protective sleeve is provided at said at least one section and wherein said wire rope is provided with reinforcing means along said discrete section.21. A method as claimed in claim 20 comprising winding a reinforcing element around said wire rope.22. A method as claimed in claim 21 wherein said reinforcing element is wound helically around said wire rope leaving spaces between turns of said reinforcing element, and wherein said protective sleeve is formed so as to extend into said spaces.23. A method as claimed in claim 21 01 22 wherein said reinforcing element is a steel band or a steel wire.24. A method as claimed in claim 20 wherein said reinforcing means is provided as part of said sleeve.25. A method as claimed in any of claims 20 to 24 wherein the sleeve is a different colour from the reinforcing means.26. A method as claimed in claim 20 wherein the protective sleeve comprises two concentric sleeves.27. A method as claimed in claim 26 comprising forming the two concentric sleeves of different colours.28. A method as claimed in claim 26 or claim 27 comprising forming the two concentric sleeves of different materials.29. A method as claimed in claim 26 comprising forming one of the sleeves of a steel band or helical wire.30. A method as claimed in any of claims 20 to 29 comprising providing the longitudinal ends of the sleeve with a taper towards the surface of the wire rope.31. A method as claimed in any of claims 20 to 30 comprising forming the protective sleeve of a thermosetting resin.32. A method as claimed in claim 31 when dependent on claim 26 comprising forming the two sleeves of the same thermosetting resin but providing said sleeves with different properties by varying the proportions of reactants and/or additives.33. A method as claimed in any of claims 20 to 32 comprising forming the sleeve with a varying thickness along its length.34. A method as claimed in claim 33 wherein the sleeve is formed so as to taper from one longitudinal end to the other longitudinal end.35. A method as claimed in any of claims 20 to 34 wherein the sleeve is formed to have a thickness of from 10% to 20% of the diameter of the wire rope.36. A method as claimed in any of claims 20 to 35 comprising forming at least two protective sleeves along the length of the wire rope.37. A method as claimed in any of claims 20 to 36 comprising forming said sleeve by a plurality of successive moulding operations.38. A method for protecting a wire rope substantially as hereinbefore described with reference to the accompanying drawings.</claim-text>