Hybrid rope

Abstract

Hybrid rope (20) comprising a core element (22) containing high modulus fibers surrounded by at least one outer layer (24) containing wirelike metallic members (26). The core element (22) is coated (23) with a thermoplastic polyurethane or a copolyester elastomer, preferably the copolyester elastomer containing soft blocks in the range of 10 to 70 wt %. The coated material (23) on the inner core element (22) is inhibited to be pressed out in-between the wirelike members (26) of the hybrid rope (20) and the hybrid rope (20) has decreased elongation and diameter reduction after being in use.

Claims

1. A hybrid rope comprising a core element containing high modulus fibers surrounded by at least one outer layer containing metallic members, wherein the core element is coated with a polymer comprising a copolyester elastomer containing soft blocks in the range of 10 to 70 wt %.

2. The hybrid rope according to claim 1, wherein a hardness Shore D of the copolyester elastomer as measured according to ISO 868 is larger than 50.

3. The hybrid rope according to claim 1, wherein the copolyester elastomer is a copolyester block copolymer with soft blocks consisting of segments of polyester, polycarbonate, polyether or a combination thereof.

4. The hybrid rope according to claim 1, wherein the high modulus fibers contain high molecular weight polyethylene (HMwPE), ultrahigh molecular weight polyethylene (UHMwPE), liquid crystal polymer (LCP), aramid, or PBO (poly(p-phenylene-2,6-benzobisoxazole).

5. The hybrid rope according to claim 1, wherein the polymer is coated on the core element by extrusion.

6. The hybrid rope according to claim 1, wherein a thickness of the polymer is larger than 0.5 mm.

7. The hybrid rope according to claim 1, wherein the hybrid rope has a diameter in a range of 2 to 400 mm.

8. The hybrid rope according to claim 1, further comprising a jacket surrounding the at least one outer layer, the jacket comprising a plastomer, thermoplastic, elastomer or combination thereof.

9. The hybrid rope according to claim 1, wherein the metallic members are steel wires, steel wire strands or combination thereof.

10. The hybrid rope according to claim 9, wherein the steel wires, the steel wire strands or the combination thereof are coated with zinc, zinc alloy or a combination thereof.

11. The hybrid rope according to claim 1, wherein the at least one outer layer comprises two or more outer layers containing metallic members.

12. The hybrid rope according to claim 1, wherein an additional plastomer layer is added in-between the core element and the polymer.

13. A method of manufacturing a hybrid rope, the method comprises the steps: (a) providing a core element, wherein the core element includes high modulus fibers; (b) coating the core element with a polymer comprising copolyester elastomer containing soft blocks in a range of 10 to 70 wt %; and (c) twisting a plurality of metallic members together around the core element to form a metallic outer layer.

14. The hybrid rope according to claim 11, wherein an additional plastomer layer is added in-between the core element and the polymer.

15. The method according to claim 13, wherein the metallic members are steel wires, steel wire strands or combination thereof.

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 prior art hybrid rope.

(3) FIG. 2 is a cross-section of a hybrid rope according to a first embodiment of invention.

(4) FIG. 3 is a cross-section of a hybrid rope according to a second embodiment of invention.

(5) FIG. 4 is a cross-section of a hybrid rope according to a third embodiment of invention.

(6) FIG. 5 is a cross-section of a hybrid rope according to a fourth embodiment of invention.

(7) FIG. 6 is a cross-section of a hybrid rope according to the invention in test comparison.

(8) FIG. 7 shows the elongation of an invention hybrid rope and reference hybrid rope vs. cycles in bending fatigue tests.

MODE(S) FOR CARRYING OUT THE INVENTION

(9) Hybrid Rope 1

(10) FIG. 2 is a cross-section of an invention hybrid rope according to a first embodiment of the invention. The invention hybrid rope 20 comprises a fiber core 22, a coated polymer layer 23, and an outer layer 24 containing metallic wirelike members 26. The hybrid rope 20 as illustrated in FIG. 2 has a 12+FC rope construction. The term 12+FC refers to a rope design with a metallic outer layer having 12 single wires and a fiber core (abbreviated as FC).

(11) The core 22 is made of a plurality of high modulus polyethylene (HMPE) yarns, e.g. any one or more of 8*1760 dTex Dyneema? SK78 yarn, 4*1760 dTex Dyneema? yarn or 14*1760 dTex Dyneema? 1760 dTex SK78 yarn. The core 22 can be made of a bundle of continuous synthetic yarns or braided strands. As an example, in a first step a 12 strand braided first core part was produced, each strand consisting of 8*1760 dTex Dyneema? SK78 yarn. This first core part is overbraided with 12 strands of 4*1760 dTex Dyneema? yarn.

(12) In a next step the coated layer 23 of copolyester elastomer, such as Arnitel?, is extruded on the core 22 as produced above using a conventional single screw extruder with the processing conditions described in the user extrusion guidelines.

(13) Thereafter, the hybrid rope is obtained by twisting twelve steel wires around the core 22. In this embodiment, the metallic wirelike members 26 as an example illustrated herewith are identical single steel wires.

(14) Alternatively, it should be understood that the metallic wirelike members 26 may be metallic strands comprising several filaments. It should be understood that the metallic outer layer 24 may also comprise a combination of filament strands and single steel wires.

(15) It should be noted that in the coated polymer layer 23 in FIG. 2 (similarly also for the coated polymer layers in the following figures) looks round but in reality it's star shaped and goes in between the strands.

(16) Hybrid Rope 2

(17) FIG. 3 is a cross-section of an invention hybrid rope according to a second embodiment of the invention. The invention hybrid rope 30 comprises a fiber core 32, an extruded copolyester elastomer layer 33 having copolyester elastomer containing soft blocks in the range of 10 to 70 wt %, a first metallic outer layer containing first metallic wirelike members 34 and a second metallic outer layer containing second metallic wirelike members 38. The hybrid rope 30 as illustrated in FIG. 3 has a 32?7c+26?7c+FC SsZs, SzZz or ZzSz rope construction. The term 32?7c+26?7c+FC SsZs refers to a rope design with the second metallic layer (most outside layer) having 32 strands (i.e. second metallic wirelike members 38) with a rotating direction of S, wherein each strand contains 7 compacted filaments with a rotating direction of s, the first metallic layer having 26 strands (i.e. first metallic wirelike members 34) with a rotating direction of Z, wherein each strand contains 7 compacted filaments with a rotating direction of s, and a fiber core (abbreviated as FC). The metallic members 34, 38 of the hybrid rope 30 as shown in FIG. 3 have an identical dimension and filament strand constructions. Alternatively, the metallic members may have different diameter and/or the other filament strand constructions.

(18) Hybrid Rope 3

(19) FIG. 4 is a cross-section of an invention hybrid rope according to a third embodiment of the invention. As an example, the illustrated hybrid rope 40 has a construction of 34+24+FC SZ. The invention hybrid rope 40 comprises a fiber core 42, an extruded copolyester elastomer layer 43 such as Arnitel? around the core 42, a first metallic outer layer containing first metallic wirelike members 44. In addition, an extruded plastomer layer 45, such as EXACT? 0230 is coated in-between the fiber core 42 and the extruded copolyester elastomer layer 43. A second metallic outer layer containing second metallic wirelike members 48 twisted in different direction of the first metallic wirelike members 44 is on top of the first metallic outer layer and a thermoplastic protection layer 49, such as polyethylene (PE) is extruded on the entire rope. Optionally, an additional coating/extruded layer, such as polyethylene (PE), can be added in between the two metallic layers to avoid fretting in between the metallic layers.

(20) Hybrid Rope 4

(21) FIG. 5 is a cross-section of an invention hybrid rope according to a fourth embodiment of the invention. As an example, the illustrated invention hybrid rope 50 comprises a fiber core 52, an extruded copolyester elastomer layer 53 around the core 52, and an outer layer 54 containing hybrid strands. Herein, the hybrid strand contains a fiber core 56, an optional extruded layer 57 and a metallic layer containing metallic wirelike members 58 around the extruded layer 57. The composition of the fiber core 56 in the outer layer may be the same as or different from that of the fiber core 52 in the central of the hybrid rope. The composition of the extruded layer 57 on the individual hybrid strand may also be the same as or different from that of the extruded layer 53 on the fiber core 52 of the hybrid rope. The metallic wirelike members 58 are preferably galvanized steel wires.

(22) Test Comparisons

(23) The advantage of present invention will be illustrated after comparison. The invention hybrid rope 60 having a rope construction as shown in FIG. 6 is produced for comparison. A fiber core 62 is enclosed by an extruded layer 63. An outer metallic layer 64 containing six steel strands 66 are around the extruded core. In each strand 66, there is 26 steel wires. The 6 strands 66 are compacted with the extruded fiber core and thus a 26 mm hybrid rope is formed. The detailed dimension of the hybrid rope is given in table 2. According to the invention, in this specific example, the core element is high modulus fiber, Dyneema?, with a diameter of 11 mm. The core is extruded with a copolyester elastomer containing soft blocks, Arnitel?, with a thickness of 1 mm.

(24) TABLE-US-00002 TABLE 2 Rope dimension of the invention rope in comparison. Hybrid Rope: 6 ? 26WS C + FC Rope diameter after strand compaction (mm) 26 Core diameter (mm) 11 Extruded layer thickness (mm) 1 Outer strand Central (mm) 0.84 diameter (8.54 mm) Interior (mm) 1.17 Warrington 2 (mm) 1.41 Warrington 1 (mm) 1.11 Exterior (mm) 2.00

(25) In order to give an explicit indication, a conventional hybrid rope having the same rope configuration and similar dimension is taken as a reference hybrid rope, wherein a polypropylene (PP) core having a core diameter of 13 mm without extruded layer is compacted directly with steel strands. The invention hybrid rope having Dyneema? core extruded with Arnitel? is compared therewith.

(26) Also for comparison, a hybrid rope having an identical Dyneema? core extruded with PP at a same thickness, i.e. 1 mm, is taken as a comparative example.

(27) Because of the great responsibility involved in ensuring being safely rigged on equipment, any wire rope in use must be clearly under its breaking load. The use of safety factor (SF) is imposed by law or standard to which a structure must conform or exceed. SF is a ratio of breaking load (absolute strength) to actual applied load, i.e.

(28) $\begin{array}{cc}\mathrm{SF}=\frac{\mathrm{Breaking\_load}}{\mathrm{Applied\_load}}& \left(1\right)\end{array}$

(29) The purpose to impose SF is to maintain the rope in the service life and strength within the limits of safety.

(30) The condition of pulley, drum or sheaves and other end fittings should be noted also. The condition of these parts affects rope wear: the smaller the bend radius of pulley, the greater the bending resistance. The hybrid ropes are tested in bending and fatigue tests performed in a severe condition, where pulley size D=514 mm, and the diameter of the rope d=26 mm i.e. D/d?20.

(31) Ropes Loaded at the Same Load:

(32) The properties, such as linear weight, breaking load, applied load and modulus, of the investigated hybrid ropes are illustrated in table 3.

(33) As shown in table 3, the linear weight of all the hybrid ropes is comparable, while the breaking load and modulus of the hybrid ropes with extruded Dyneema? core (D2) are higher than the reference hybrid rope with PP core (P). This could be attributed to the higher modulus of Dyneema? core since the applied load is shared by the steel outer layer and fiber core, and the outer steel layer bears a same load.

(34) Importantly, in bending and fatigue tests, the invention hybrid rope presents super properties.

(35) The invention hybrid rope (D2) is compared with a hybrid rope having a Dyneema? core extruded with PP (table 3 comparative example 1, D1) and reference rope (P in table 3) at a same applied load, i.e. 8.81 tones.

(36) In this case, the SF of hybrid rope having Dyneema? core extruded with Arnitel? (D2) is higher than that of the reference hybrid rope with PP core (P), i.e. 5.9 vs. 5.2. Importantly, the reference hybrid rope with PP core (P) is destructed after about 110.000 cycles, while the hybrid rope having Dyneema? core extruded with Arnitel? (D2) gives about 40% more cycles to destruction, i.e. being broken after about 150.000 cycles.

(37) TABLE-US-00003 TABLE 3 Hybrid ropes in comparison. Core of Break- the Linear ing Applied Safety Hybrid Weight Load Load Factor Modulus Ropes (kg/m) (tons) (tons) (SF) (GPa) Invention Dyneema? 2.69 52.37 8.81 5.9 89.81 Example core (D2) extruded with Arnitel? Comparative Dyneema? 2.75 52.17 8.81 5.9 87.98 Example 1 core (D1) extruded with PP Reference PP core 2.75 46.07 8.81 5.2 76.00 (P) without extruded layer

(38) Moreover, the SF of the comparative hybrid rope (D1) (SF=5.9) is also higher than the reference rope (SF=5.2). The elongation and diameter reduction due to bending and fatigue of the comparative hybrid rope (D1) after being in use is less than that of the reference rope, i.e. a hybrid rope without coating on the core (P).

(39) In addition, the invention hybrid rope (D2) shows significantly less elongation and less diameter reduction compared with both the comparative hybrid rope (D1) and reference hybrid rope (P). The diameter reduction is down to 1% for D2, while 2% for D1 and 3% for P. Also, less wire breaks are found in the invention hybrid rope (D2) after being in use for certain cycles.

(40) Ropes Loaded at the same Safety Factor:

(41) In the bending and fatigue tests, the SF of 5 takes account of the cyclic load that the invention and reference hybrid ropes are subjected to, i.e. the actual applied load is ? of the breaking load of the hybrid rope.

(42) TABLE-US-00004 TABLE 4 Hybrid ropes in comparison. Break- Applied Linear ing Load Mod- Core of the Weight Load (tons) @ ulus Hybrid Ropes (kg/m) (tons) SF = 5 (GPa) Invention Dyneema? core 2.69 52.37 9.9 89.81 Example (D3)* extruded with Arnitel? Reference PP core without 2.75 46.07 8.81 76.00 (P)* extruded layer *Elongations of the hybrid ropes during bending and fatigue test are shown in FIG. 7.

(43) As shown in table 4, at the same safety factor, i.e. SF=5, the applied load on the invention hybrid rope of Dyneema? core extruded with Arnitel? (D3) is 9.9 tons vs. 8.81 tones of the applied load on the reference hybrid rope with PP core (P). Even if about 13% more load is applied on the invention hybrid rope (D3), the invention hybrid rope (D3) shows significantly less elongation after same number of cycles compared with reference rope (P) as shown in FIG. 7. This result is consistent with the measurement of diameter reduction after same number of cycles: Less diameter reduction, which is around 1.3% with the invention hybrid rope (D3), compared with diameter reduction of reference rope (P) which is around 2.9%. The development of elongation and diameter reduction will close the gaps between the metallic or steel wires and enhance their friction/fretting and eventually result in the break of wires. Indeed, the wire breaks earlier and more for the reference hybrid rope than the invention hybrid rope after being in use for certain cycles.

(44) The invention hybrid rope indicates a guaranteed reliability and long life time and thus is suitable for critical applications.

(45) 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.

LIST OF REFERENCES

(46) 10 composite cable 12 synthetic core 14 metal jacket 16 wire 20 hybrid rope 1 22 fiber core 23 coated polymer layer 24 outer layer 26 metallic wirelike member 30 hybrid rope 2 32 fiber core 33 extruded copolyester elastomer layer 34 first metallic wirelike member 38 second metallic wirelike member 40 hybrid rope 3 42 fiber core 43 extruded copolyester elastomer layer 44 first metallic wirelike member 45 coated plastomer layer 48 second metallic wirelike member 49 thermoplastic protection layer 50 hybrid rope 4 52 fiber core 53 extruded copolyester elastomer layer 54 outer layer 56 fiber core 57 extruded layer 58 metallic wirelike member 60 hybrid rope 62 fiber core 63 extruded layer 64 outer metallic layer 66 steel strand