Synthetic fiber rope

Abstract

A synthetic fiber rope comprising:—a core, said core being a laid or braided synthetic fiber strand,—a polymer layer, said polymer layer covering said core,—a first layer, said first layer having at least six first synthetic fiber strands laid in a first direction surround said polymer layer, and—a second layer, said second layer having at least twelve second synthetic fiber strands laid in a second direction surround said first layer.

Claims

1. A synthetic fiber rope comprising a core, said core being a laid or braided synthetic fiber strand, a polymer layer, said polymer layer covering said core, a first layer, said first layer having at least six first synthetic fiber strands laid in a first direction surround said polymer layer, and a second layer, said second layer having at least twelve second synthetic fiber strands laid in a second direction surround said first layer, wherein said core has cross-sectional area in a range of 5 to 10% relative to a combined cross-sectional area of the polymer layer, the first layer, and the second layer, or said first layer or said second layer has an area in a range of 40 to 60% of the total cross-section area of the synthetic fiber rope.

2. The synthetic fiber rope according to claim 1, wherein each of said core, said first layer and said second layer has a lay factor in a range from 3 to 15.

3. The synthetic fiber rope according to claim 1, wherein said core has a lowest lay factor, and said first layer has a lower lay factor than said second layer.

4. The synthetic fiber rope according to claim 1, wherein said first direction is “S” direction and said second direction is “Z” direction, or said first direction is “Z” direction and said second direction is “S” direction.

5. The synthetic fiber rope according to claim 1, wherein said first layer and/or said second layer are covered with a protective layer.

6. The synthetic fiber rope according to claim 5, wherein said protective layer is braided and/or extruded.

7. The synthetic fiber rope according to claim 1, wherein said first synthetic fiber strands and said second synthetic fiber strands are individually covered with a further layer.

8. The synthetic fiber rope according to claim 1, wherein said first synthetic fiber strands and said second synthetic fiber strands are not individually covered with a further layer.

9. The synthetic fiber rope according to claim 1, wherein at least one of said first synthetic fiber strands and said second synthetic fiber strands is a laid strand and comprises two or three or more layers of rope yarns.

10. The synthetic fiber rope according to claim 9, wherein said two or three layers of the laid yarn are laid in different directions.

11. The synthetic fiber rope according to claim 1, wherein said synthetic fiber rope comprise high modulus synthetic fibers or blended high modulus synthetic fibers selected from the group consisting of ultra-high molecular weight polyethylene (UHMwPE or UHMPE), high molecular weight polyethylene (HMwPE or HMPE), aramid, liquid crystal polymer (LCP), and poly(p-phenylene-2,6-benzobisoxazole (PBO).

12. The synthetic fiber rope according to claim 1, wherein at least one of said core, said first layer or said second layer comprises two different high modulus synthetic fibers.

13. The synthetic fiber rope according to claim 1, wherein said core, is made by different high modulus synthetic fibers from said first layer and said second layer.

Description

BRIEF DESCRIPTION OF FIGURES IN THE DRAWINGS

(1) The invention will be better understood with reference to the detailed description when considered in conjunction with the non-limiting examples and the accompanying drawings, in which:

(2) FIG. 1 is a cross-section of a synthetic fiber rope according to a first embodiment of invention.

(3) FIG. 2 shows the stress vs. strain relationship of the entire synthetic fiber rope compared with the stress vs. strain relationship of the core and the first layer at the same elongation levels.

(4) FIG. 3 is a strand construction with three levels/layers.

(5) FIG. 4 shows an invention synthetic fiber rope according to a second embodiment of invention.

MODE(S) FOR CARRYING OUT THE INVENTION

(6) FIG. 1 is a cross-section of an invention synthetic fiber rope according to a first embodiment. The invention synthetic fiber rope 10 comprises a fiber core 12, an extruded polymer layer 14, a first layer 17 and a second layer 19. The core is a “six-strand”, i.e. six strands (core outer) that are closed around a center strand (core inner). The first layer 17 has six first synthetic fiber strands laid in a first direction (closing direction of the first layer) surround said extruded polymer layer 14. The second layer 19 has twenty second synthetic fiber strands laid in a second direction (closing direction of the second layer) surround said first layer 17. The “valleys” 16 between the first synthetic fiber strands and the “valleys” 18 between the second synthetic fiber strands are minimized and are much smaller compared with braided rope constructions.

(7) The extruded polymer layer 14 can be in a tubular formation and can be manufactured from a variety of materials including polypropylene (PP), polyethylene (PE), PP/PE blends, nylon, Hytrel® and Arnitel®.

(8) The lay factors and the closing directions of each layer are shown in table 1 below. In this content, closing direction “A” or “B” refers to either left or right twist directions (“S” or “Z”), and “A” and “B” refer to different twist directions.

(9) TABLE-US-00001 TABLE 1 Rope lay factors and closing directions Rope lay factors and closing direction Layer Lay factor Closing direction Core inner 5.5 Core outer 6 A First layer 6.25 B Second layer 6.5 A

(10) FIG. 2 shows the stress of the entire synthetic fiber rope compared with the stress of the core and the first layer at the same elongation levels. The stress σ (% stress a at the Break Load) of the entire synthetic fiber rope as a function of strain ε (%) is indicated by curve A whilst the stress a of the core and the first layer as a function of strain ε (%) is indicated by curve B. As shown in FIG. 2, curve A and curve B present similar stress at the same strain level. It illustrates that the entire rope, the core, the first layer and thus each layer of the rope have similar load-elongation properties. Thanks to the lay factors, all fibres are loaded almost equally whilst also minimising torque and rotation.

(11) Here, the first synthetic fiber strands 17 and the second synthetic fiber strands 19 have two or three layers or levels. As shown in FIG. 3, an example strand 30 has three levels: king yarn 32, inner level 34 and outer level 36. Rope yarns 35, 37 in each level 34, 36 are of a single size but need not be the same size in each level 34, 36. The inner level 34 of the strand contains between 20% and 40% of total strand material and the remaining material is distributed around the other part of the strand. Stranding lay factors of each level of a strand and each layer of the synthetic fiber rope are shown in Table 2. Twist directions in each level of the first layer of synthetic fiber rope are shown in Table 3. Twist directions in each level of the second layer of synthetic fiber rope are shown in Table 4.

(12) Each strand can be applied without cover or coating. Alternatively, each strand can also have a protective cover of braided layer or coating/extrusion applied.

(13) TABLE-US-00002 TABLE 2 Stranding lay factors of each level of a stran and each layer of the synthetic fiber rope Stranding lay factors (LF) Layer Core inner Core outer First layer Second layer King yarn  6-10  8-12  8-12  8-12 Inner level NA NA 5-9 5-9 Outer level 5-7 7-9 7-9 7-9

(14) Rope yarn may have a lay factor of 15-25 in all layers, except for king yarns which use a lay factor of between 6-10 for the core inner and 8-12 for the core outer, the first layer and second layer.

(15) TABLE-US-00003 TABLE 3 Twist directions in each level of the first layer of synthetic fiber rope First layer (Closing direction B) Strand Strand levels opposite direction Strand levels same direction position King yarn Rope yarn Strand King yarn Rope yarn Strand Inner A B A B A B Outer A B A B

(16) TABLE-US-00004 TABLE 4 Twist directions in each level of the second layer of synthetic fiber rope Second Layer (Closing direction A) Strand layers Strand layers Strand opposite direction same direction posi- King Rope King Rope tion yarn yarn Strand yarn yarn Strand Inner B A B A B A Outer B A B A

(17) A series of twist directions as shown in table 3 and 4 reduce internal contact angles (increased resistance to internal wear), maximise external wear resistance, reduce torque and rotation characteristics and give optimised strength conversion.

(18) FIG. 4 shows an invention synthetic fiber rope according to a second embodiment of the invention. The invention synthetic fiber rope 40 comprises a fiber core 42, an extruded polymer layer 44, a first layer 46 and a second layer 48. Different from the above first embodiment, in this embodiment, the fiber core 42 has a braided construction and the extruded polymer layer 44 has a fluted shape. The first layer 46 and the second layer 48 are the same as the above first embodiment.

(19) The invention synthetic fiber rope has a number of features to give the advances in performance with a combination of low and predictable rotation properties, high bending fatigue resistance, high strength and high radial stability and stiffness.

(20) It should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the inventions embodied herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention.

REFERENCE NUMBERS

(21) 10, 40 synthetic fiber rope

(22) 12, 42 fiber core

(23) 14, 44 extruded polymer layer

(24) 17, 46 first layer

(25) 16 valley between first synthetic fiber strands

(26) 19, 48 second layer

(27) 18 valley between second synthetic fiber strands

(28) 30 strand

(29) 32 king yarn

(30) 34 inner level

(31) 35, 37 rope yarn

(32) 36 outer level