Description

Technical Field [0001 ] The invention relates in general to a synthetic fiber rope and in particular to a synthetic fiber rope with a spliced termination and a production method thereof.

Background Art [0002] Synthetic fiber ropes may for example be used in hoisting and pulling operations, for example as crane cables, in deep see installation, marine and off-shore mooring, commercial fishing, for example as warp lines for nets, and in mining operations. Existing synthetic fiber rope solutions for the applications in hoisting and pulling have generally utilised braided rope constructions partially or entirely made from high modulus polyethylene

(HMPE). Due to strand crossovers, followed by lower packing factors and lower radial stability, such constructions may have intrinsically inferior performance properties, e.g., lower strength and inferior fatigue life. The use of braided constructions has also tended to limit material choices to HMPE, liquid crystal polymer (LCP) or HMPE/LCP blends since the internal abrasion generated by the strand cross-over in braided constructions may not be optimal for aramid materials and lead to premature failure compared with a braided HMPE rope. To overcome radial stiffness issue, some braided rope designs have utilised non-load bearing central cores (e.g. continuous filament polyester bundles or extruded polyurethane) to the otherwise hollow braided constructions to improve radial stability. However, this addition is at the expense of global material fill factor.

[0003] A specialized construction of synthetic fiber ropes is described in the international patent application WO2019/185487 for high fiber strength conversion efficiency and fatigue resistance. The synthetic fiber rope has a laid construction with a polymer-coated synthetic fiber core and two layers of synthetic fiber strands laid around the synthetic fiber core. [0004] For rope applications, it is necessary to properly terminate the synthetic fiber rope, because via the rope termination tension in the rope is transferred to for example a hook on a crane block or an anchoring point of the rope or a shackle. In the prior art, spliced eyes or sockets are applied as terminations for synthetic fiber rope with braided construction. There is no guidance in state of the art with respect to the terminations of synthetic fiber rope with laid construction. If a termination applied to a synthetic fiber rope with a laid construction is not strong enough, and especially after a long period of being used under load, the termination can fail.

Disclosure of Invention

[0005] The object of the present invention is to provide a synthetic fiber rope having a laid construction and a strong and stable splice-type termination.

[0006] Another object of the present invention is to provide a method of making a strong and stable splice termination for a synthetic fiber rope with laid construction.

[0007] In order to achieve the aforementioned objects, the present invention provides a synthetic fiber rope comprising a fiber core and at least a layer of synthetic fiber strands twisted around said fiber core. The synthetic fiber rope has a splice-type termination and said splice-type termination comprises

-a cloth or tape covered rope section bent into an “eye” shape,

-a spliced rope section next to the “eye” shaped rope section, the spliced rope section being made by tucking a number of bundled tails of the synthetic fiber rope respectively through between the synthetic fiber strands of the outer layer of the synthetic fiber rope.

[0008] The synthetic fiber rope of the invention comprises all types of synthetic fibers material. Examples of fibers are nylon or polyamide fibers, polyester fibers, polyolefin fibers such as polypropylene and polyethylene fibers, and particularly high strength synthetic fibers such as high strength polypropylene (HSSP), high modulus polyethylene (HMPE), ultra high molecular weight polyethylene (UHMwPE), para-aramid fibers such as poly(P-phenylene terephthalamide) (PPTA) fibers, liquid crystal polyester (LCP/LCAP), poly(P-phenylene-2,6-benzobisoxazole) (PBO), meta-aramid fibers such as poly (m-phenylene isophthalamide fibers, copolyamide fibers of (terephthaloyl chloride, P-phenylenediamine, 3,4'-diaminodiphenyl ether), normally referred to as "copolymer aramid"). The polymer materials may be present not only in fiber format but also in other longitudinal format such as a tape, filament and rods. Various different fibers may also be combined in one strand and / or in one rope.

[0009] At the splice-type termination of the synthetic fiber rope according to the invention, the number of tails of the synthetic fiber rope preferably equals the number of synthetic fiber strands at the outer layer of the synthetic fiber rope. As an example, the synthetic fiber rope has two layers, and the tails of synthetic fiber rope is made by dividing and bundling up the core and two layers yarns equally amongst the number of strands of the outer layer of the synthetic fiber rope. As another example, the synthetic fiber rope has three layers, and the tails of synthetic fiber rope is made by dividing and bundling up the core, the layer one, layer two and layer three yarns equally amongst the number of strands of the outer layer of the synthetic fiber rope. Herein, layer three is the outer layer of the synthetic fiber rope. Also, the synthetic fiber rope can have four layers, and the tails of synthetic fiber rope is made by dividing and bundling the core, the layer one, layer two and layer three yarns equally amongst the number of layer four strands.

With respect to the synthetic fiber rope, its fiber core may be covered by a polymer coating. As an example, the fiber core of the synthetic fiber rope is a laid or braided synthetic fiber strand, and the at least a layer of synthetic fiber strands comprise a first layer and a second layer, wherein, said first layer preferably has at least six first synthetic fiber strands laid in a first direction surround said polymer layer, and said second layer preferably has at least twelve second synthetic fiber strands laid in a second direction surround said first layer. [0010] According to a second aspect of the invention, it is provided a method of making a splice termination for a synthetic fiber rope having a laid construction, wherein the synthetic fiber rope comprises a fiber core and at least a layer of synthetic fiber strands twisted around said fiber core. The method comprises the following steps:

(a) Providing a synthetic fiber rope having a laid construction and an unrestrained end,

(b) Measuring tails having a length of L1 from the end of the rope, applying cloth or tape on the synthetic fiber rope for a length L2 from the unrestrained end of tails to form a taped section,

(c) Bending the synthetic fiber rope at the point having a length of about L1 +L2/2 from the unrestrained end of the rope to form an “eye”,

(d) Untwisting the core and the strands of the tails, dividing and bundling up the yarns equally amongst the number strands of the outer layer of the synthetic fiber rope has so that forming a plurality of bundled tails,

(e)Tucking and pulling the plurality of bundled tail(s) respectively through between respective strand(s) of the outer layer of the synthetic fiber rope next to the taped section to form a tucked section,

(f) Repeating step of tucking and pulling the plurality of bundled tail(s) respectively through between respective strand(s) of the outer layer of the synthetic fiber rope next to the previously tucked section to form a spliced termination.

[0011] According to the invention, said fiber core can be coated with a polymer coating and then said step (d) includes a step of removing said polymer coating, e.g., via knife or hot melting.

[0012] As an example, the synthetic fiber rope has two layers, and step (d) comprises of dividing and bundling up the core and two layers yarns equally amongst the number of strands of the outer layer of the synthetic fiber rope. As another example, the synthetic fiber rope has three layers, and step (d) comprises of dividing and bundling up the core, the layer one, layer two and layer three yarns equally amongst the number of strands of the outer layer of the synthetic fiber rope. Herein, layer three is the outer layer of the synthetic fiber rope. Also, the synthetic fiber rope can have four layers and step (d) comprises of dividing and bundling up the core, the layer one, layer two and layer three yarns equally amongst the number of layer four strands.

[0013] The method of the invention can further comprise step (g) removing a part of the yarn content on each step of the tucks for a plurality of tapers. [0014] The synthetic fiber rope with a spliced termination of the invention has made by a short length of a synthetic fiber rope. This is one of the advantages of the splice according to the invention over others, especially over splice of braided synthetic fiber ropes. The spliced termination and in particular the tucking section has a compact diameter. More importantly, the spliced termination according to the present invention has a high strength or breaking load. The splicing process can be done even manually by skilled person offshore or on site.

Brief Description of Figures in the Drawings [0015] The following detailed description makes reference to the accompanying drawings, in which:

[0016] FIG. 1-5 illustrate step-by-step schematic of a splicing method according to the present invention.

[0017] FIG. 5 illustrates a final schematic view of a splice of a synthetic fiber rope in accordance with the present invention;

Mode(s) for Carrying Out the Invention

[0018] The following description will be based on a preferred embodiment of the invention. As will be evident to the skilled person, however, the invention is not restricted to this particular embodiment.

[0019] The present embodiment of the invention is directed to a synthetic fiber rope having a polymer extruded core and multi-strand. The synthetic rope in the example has a rope construction of 5-8-8-24, i.e. , the outer layer of the synthetic rope having 24 strands, layer two having 8 strands, layer one having 8 strands and the core having 5 strands. Flerein, the synthetic fiber rope has three layers outside the core. The synthetic rope has a diameter of 88 mm. [0020] As illustrated in Fig.1 , measure tails having a length of L1 from the end of the synthetic rope 10, tying a clove hitch 12 at this point if needed. Measure eye size L2, from the first clove hitch 12, tying a second clove hitch 14 at this point if needed. L2, which denote the eye, is preferably to be calculated so that each side of the eye does not exceed an angle of 30° and preferably not exceed an angle of 15°. Mark the tucking pitch 16 of splice. Apply cloth or tape, e.g. HMPE, on the synthetic fiber rope between the two clove hitches 12,14, which denote the eye to form a taped section.

[0021] Form eye 22 by passing tails to the right-hand side as illustrated in Fig. 2. Preferably, tie both legs together with a third clove hitch so that the previous two clove hitches line up, forming the eye (not shown in Fig. 2). Such third clove hitch can also increase the cohesive force of the tucking section since it exerts a normal compression force in the tucking section.

[0022] Then, secure the rope at e.g., a working station. Remove the tape from the end of the tails. Tape up the end of each of the outer strands individually. Flalve the outer strands into top and bottom. In case of layer 4, this would equate to 12 top and 12 bottom; for layer 3, this would equate to 4 top and 4 bottom. Flalve layer 2 yarns into top and bottom -this equates to 4 top and 4 bottom. Flalve the layer 1 yarns into top and bottom - this equates to 2 top and 3 bottom.

[0023] In case, there is an extruded polymer on the individual layer, the extruded layer can be removed, e.g., using a hot knife. As shown in Fig. 3, the of the synthetic rope 30 is extruded by a polymer layer 34. The extrusion shall be cut out as close to the eye as possible.

[0024] Then, untwisting the core and the strands of the tails, dividing and bundling up the yarns equally amongst the number strands of the outer layer of the synthetic fiber rope has so that forming a plurality of bundled taped tails. As an example, the strands of layer three are broken down into yarns across the core, layer one and layer two and generate, e.g., 54 yarns.

[0025] Divide and tape up the yarns of the core, layer one, and layer two equally amongst the number of layer three strands the synthetic rope has. For the example rope, this equals 54 inner yarns divide 24 (layer three strands), giving 2.25 inner yarns per layer three strand. And then separate into top and bottoms once again.

[0026] As shown in Fig. 4, tucking and pulling the plurality of tapped tail(s) 42 respectively through respective strand(s) of the outer layer of the synthetic fiber rope next to the taped section 44. For instance, take a strand on the standing part at about “10 o’clock” on the rope and insert e.g. a Swedish fid. On the tails, choose a grouping of yarns/strand that is at about “9 o’clock” of the respective part of the rope. Loosely pull this strand underneath the strand on the standing part of the rope. Take the strand above on the standing part of the rope, insert fid, and pull through the next tail, ensuring that it exits at the pitch mark. Repeat this for all top grouped tails.

[0027] Rotate the rope, take the bottom tails and continue to tuck them under the correct strands on the standing part of the rope. Pull all the tails tight and ensure that they are exiting at the defined tuck mark 46. [0028] Repeat the splicing procedure to form a spliced termination. In each tuck starting with the final tail from the previous tuck, until reaching the desired tuck mark. Caution shall be taken to ensure that all strands exit at the correct tuck markers at each point.

[0029] The finished product is illustrated in Fig. 5. Preferably, the amount of yarns are reduced at the last few tucks to form a taper region 52. At the starting point the tapering, remove e.g. a sixth of the yarn content on each step of the tucks for five tapers. Product may require a braiding over the top of the outboard end of the rope, depending on design.