Hybrid rope or hybrid strand

Abstract

A hybrid rope (40) or a hybrid strand (50) comprising a core element (42, 52), a first (44, 54) and a second (46, 56) metallic closed layer surrounding said core element (42, 52). The core element (42, 52) includes a bundle of synthetic yarns. The first metallic closed layer (44, 54) includes a plurality of first strands of wires helically twisted together with the core element (42, 52) in a first direction. The second metallic closed layer (46, 56) includes a plurality of second wires or strands helically twisted together with said core element (42, 52) and said first metallic closed layer (44, 54) in a second direction. The cross-sectional area of the core element (42, 52) is larger than the total cross-sectional area of the first (44, 54) and second (46, 56) metallic closed layers. A corresponding method of producing such a hybrid rope or hybrid strand is also disclosed.

Claims

1. A hybrid rope, comprising a core element, a first and a second metallic closed layer surrounding said core element, wherein the core element includes a bundle or construction of synthetic yarns, the first metallic closed layer includes a plurality of first wirelike members helically twisted together around the core element in a first direction, the second metallic closed layer includes a plurality of second wirelike members helically twisted together around said core element and said first metallic closed layer in a second direction, and wherein the cross-sectional area of the core element is larger than the total cross-sectional area of the first and second metallic closed layers.

2. The hybrid rope as in claim 1, wherein the ratio of the cross-sectional area of the core element to the total cross-sectional area of the first and second metallic closed layers is 60:40.

3. The hybrid rope as in claim 1, wherein said hybrid rope has a diameter in the range of 10 to 400 millimeter.

4. The hybrid rope as in claim 1, further comprising a jacket surrounding the second metallic closed layer, said jacket comprising a plastomer, thermoplastic, a braided cover and/or elastomer.

5. The hybrid rope as in claim 1, wherein the wirelike members are steel wires and/or steel wire strands.

6. The hybrid rope as in claim 5, wherein the steel wires and/or steel wire strands are coated with zinc and/or zinc alloy.

7. The hybrid rope as in claim 5, wherein the steel wires and/or steel wire strands are end galvanized.

8. The hybrid rope as in claim 1, wherein said first wirelike members have a first diameter, said second wirelike members have a second diameter, and the first diameter is different from the second diameter.

9. The hybrid rope as in claim 1, wherein said first wirelike members have a first diameter, said second wirelike members have a second diameter, and the first diameter is equal to the second diameter.

10. The hybrid rope as in claim 1, wherein the spin efficiency of the wirelike members is more than 90%.

11. The hybrid rope as in claim 1, wherein the first twist direction and the second twist direction are different lay directions.

12. The hybrid rope as in claim 1, wherein the core has a laid or a braided construction and the core element is coated with a plastomer, thermoplastic, braided cover and/or elastomer.

13. An assembly of a hybrid rope and a socket, wherein the hybrid rope is as in claim 1 and the rope is terminated at least at one of its ends by a socket having a conically shaped space, and wherein the conically shaped space of the socket has a conical angle of between 2 and 8 and a length A of between 5D and 20D, D being the smallest diameter of the conically shaped space, steel wires having been untwisted at said at least one of the ends, an open space around the untwisted wires and core in the socket being filled with a resin.

14. A method of producing a hybrid rope comprising a core element, a first and a second metallic closed layer, wherein the cross-sectional area of the core element is larger than the total cross-sectional area of the first and second metallic closed layers, comprising the steps of: (a) providing the core element, wherein said core element includes a bundle or construction of synthetic yarns; (b) twisting a plurality of first wirelike members together around the core element in a first direction to form the first metallic closed layer; (c) twisting a plurality of second wirelike members together around said core element and said first metallic closed layer in a second direction to form the second metallic closed layer.

15. A method of producing a hybrid rope as in claim 14, further comprising the step of: (d) coating the rope with a plastomer, thermoplastic, a braided cover and/or elastomer to form a jacket outside the second metallic closed 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 prior art hybrid rope.

(3) FIG. 2 is an intersection of a socket used for the hybrid rope according to the invention.

(4) FIG. 3 is a socket used for the hybrid rope according to the invention in longitudinal direction.

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

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

(7) FIG. 6 is a cross-section of an invention hybrid rope according to the third embodiment of the invention.

(8) FIG. 7 shows a loading scheme for quasi-dynamic measurement.

(9) FIG. 8 shows comparisons of quasi-dynamic stiffness values of hybrid rope (A) and full steel rope (B) at different breaking load levels.

(10) FIG. 9 shows comparisons of quasi-dynamic specific stiffness values of hybrid rope (A) and full steel rope (B) at different breaking load levels.

(11) FIG. 10 shows creep over time at constant loads of hybrid ropes (A,D) and full steel rope (C).

MODE(S) FOR CARRYING OUT THE INVENTION

(12) Hybrid Rope 1

(13) FIG. 4 is a cross-section of an invention hybrid rope according to the first embodiment of the invention. The invention hybrid rope 40 comprises a fiber core 42, first metallic wirelike members 44 and second metallic wirelike members 46. The hybrid rope 40 may have a diameter ranging from 10 mm to 400 mm. The hybrid rope 40 as illustrated in FIG. 4 has a 327c+267c+FC SsZs, SzZz or ZzSz rope construction. The term 327c+267c+FC SsZs refers to a rope design with the second metallic layer (most outside layer) having 32 strands (i.e. second metallic wirelike members 46) 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 44) 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 rope construction as shown in table 1 are denoted in a similar way. The metallic members 44, 46 of the hybrid rope 40 as shown in FIG. 4 have an identical dimension and filament strand constructions. Alternatively, the metallic members may have different diameter and/or the other filament strand constructions. Table 1 gives the details of some example hybrid ropes, but not limits the present invention.

(14) The core 42 is made of a plurality of high modulus polyethylene (HMPE) yarns, e.g. any one or more rope yarns of 8*1760 dTex Dyneema SK78 yarn, 4*1760 dTex Dyneema yarn or 14*1760 dTex Dyneema 1760 dTex SK78 yarn. The core 42 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.

(15) In this embodiment, the diameter of the first metallic wirelike members 44 may be the same or different from the second wirelike members 46 (see table 1). The metallic wirelike members 44,46 as an example illustrated herewith are stands having a plurality of substantially identical metallic filaments. It should be understood that the metallic wirelike members may have different strand configuration. In addition, the metallic layers may include metallic wirelike members with different strand configuration. It should be understood that the metallic layers may also comprise a combination of filament strands and single steel wires.

(16) Hybrid Rope 2

(17) FIG. 5 is a cross-section of an invention hybrid rope according to the second embodiment of the invention. The invention hybrid rope 50 comprises a fiber core 52, first metallic wirelike members 54 and second metallic wirelike members 56. FIG. 5 schematically shows, as an example, a hybrid rope having a construction of 34+24+FC SZ. Being differential from the first embodiment, the metallic wirelike members 44,46 are each replaced by a single steel wire 54,56. The hybrid rope has a construction of 34+24+FC SZ, meaning that the hybrid rope has a fiber core, the first metallic layer with a rotating direction of S having 24 wires and the second metallic layer with a rotating direction of Z having 32 wires. The particulars of some possible hybrid rope constructions are given in table 2. It should be understood that the metallic layers may also comprise a combination of filament strands and single steel wires.

(18) TABLE-US-00001 TABLE 1 First Second metallic metallic Rope Core member member Core Rope diameter Torque diameter diameter diameter section construction (mm) factor (mm) (mm) (mm) (% of area) 32 7c + 26 7c + FC SsZs 22 0.033 14.8 1.8 1.8 57.4 32 7c + 26 7c + FC SzZz 22 0.044 14.8 1.8 1.8 57.4 32 7c + 26 7c + FC ZzSz 22 0.033 14.8 1.8 1.8 57.4 34 7c + 24 7c + FC SsZs 22 0.019 14.6 2.0 1.7 56.8 34 7c + 24 7c + FC SzZz 22 0.031 14.6 2.0 1.7 56.8 34 7c + 24 7c + FC ZzSz 22 0.019 14.6 2.0 1.7 56.8 32 7c + 26 7c + FC SsZs 100 0.033 67.2 8.2 8.2 57.4 32 7c + 26 7c + FC SzZz 100 0.044 67.2 8.2 8.2 57.4 32 7c + 26 7c + FC SzZz 100 0.034 66.0 8.5 8.5 54.9 32 7c + 26 7c + FC ZzSz 100 0.033 67.2 8.2 8.2 57.4 32 7c + 26 7c + FC ZzSz 100 0.022 66.0 8.5 8.5 54.9 34 7c + 24 7c + FC SsZs 100 0.019 66.6 9.0 7.7 56.8 34 7c + 24 7c + FC SzZz 100 0.031 66.6 9.0 7.7 56.8 34 7c + 24 7c + FC ZzSz 100 0.019 66.6 9.0 7.7 56.8

(19) TABLE-US-00002 TABLE 2 First Second metallic metallic Rope Core member member Core Rope diameter Torque diameter diameter diameter section construction (mm) factor (mm) (mm) (mm) (% of area) 26 + 32 + FC SZ 22 0.026 14.6 1.4 2.3 51.65 32 + 26 + FC SZ 22 0.013 14.6 1.9 1.9 52.06 32 + 32 + FC ZS 22 0.017 15.2 1.5 1.9 55.65 34 + 24 + FC SZ 22 0.01 14.4 2.0 1.8 51.29 26 + 32 + FC SZ 100 0.026 66.2 6.7 10.2 51.65 32 + 26 + FC SZ 100 0.013 66.2 8.5 8.5 52.06 32 + 32 + FC ZS 100 0.017 69.2 7.0 8.4 55.65 34 + 24 + FC SZ 100 0.01 65.6 9.2 8.0 51.29

(20) Hybrid Rope 3

(21) FIG. 6 is a cross-section of an invention hybrid rope according to the third embodiment of the invention. As an example, the illustrated hybrid rope has a construction of 34+24+FC SZ. The invention hybrid rope 60 comprises a fiber core 62, a extruded thermoplastic layer 63 around the core 62, first metallic wirelike members 64, second metallic wirelike members 66 and a thermoplastic protection layer 68.

(22) As an example, a coating of a plastomer EXACT 0230 is extruded on the core of the rope using a Collin 45 mm single screw extruder. Polyethylene (PE) is extruded on the entire rope as a protection layer.

(23) It goes without saying that either only an extruded coating on the core (and no extruded layer on the entire rope) or merely an extruded layer on the entire rope (and no extruded coatings on the core) are also within the scope of the invention. In addition, an additional coating/extruded layer can be added in between the two metallic layers to avoid fretting in between the metallic layers.

(24) Hybrid Rope with Socket

(25) As an example, hybrid rope having a construction of 32+26+FC SZ is connected to a socket as shown in FIGS. 2 and 3. The conically shaped space of the socket has the dimensions: A=8.8D (D is the diameter of the rope) =230.

(26) Both ends of the ropes are terminated with the socket. The end of the rope is put through the small diameter opening of the socket. Then the rope and the strands of the rope are untwisted over a distance of A+D. Thereafter the wires and yarns of the rope are spread into the shape of the hollow conically shaped space of the socket. The untwisted and spread end of the rope is thereafter pulled into the conically shaped space. The socket containing the untwisted and spread end of the rope is placed in a vertical position, with the wide opening of the conically shaped space of the socket pointing in upward direction.

(27) After that an unsaturated polyester two component resin, e.g. Socket Fast Blue, or epoxy two component resin is mixed and poured into the socket, to fill the open spaces between the yarns and wires of the unraveled and spread rope end. The resin is allowed to cure for a period of 24 hours at room temperature (20 C.). The length of the ropes is 4 m.

(28) The ropes are tested according to ISO 2307. The ropes are attached by their sockets to a standard rope break test equipment. The rope are pre-tensioned 5 times to about 50% of their expected strength indicated by breaking load (BL). Thereafter the ropes were tensioned until breaking. The breaking strength of the ropes is reported in table 3. Three hybrid ropes with the same configuration are individually tested and deviation is also given in table 3. As a reference, full steel half/full-lock steel rope and polyester rope are also listed.

(29) TABLE-US-00003 TABLE 3 Linear Rope Rope Diameter weight BL E-modulus type construction (mm) (kg/m) (tons) (GPa) Hybrid 32 + 26 + FC 22.5 0.5 1.48 0.5 47.8 90-100 SZ 1.0 Full steel Half/full-lock 22 ~2.75 ~41.8 140-150 Strand 22 ~2.38 40.9 Polyester parallel strand 40-45 ~1.20 40-45 20-30 or parallel yarn

(30) The tested hybrid ropes present consistent results. The E-modulus of the hybrid rope is in between the range of full steel and polyester ropes. It should be noted that the given E-modulus values for ropes listed under Table 3 are typically expected values other than hybrid rope. Compared with a full steel wire having a similar diameter, the hybrid rope lower the weigh by 37-46% while enhance the breaking load by 4-17%. In contrast to the polyester rope, although the hybrid rope has 25% higher linear weight, the diameter of the polyester rope is about two times of that of the hybrid rope in order to achieve a similar break strength.

(31) The quasi-dynamic stiffness is also evaluated on 22 mm hybrid rope (A) and 22 mm full steel rope (strand, 35K7) (B). The stiffness values measured correspond to those required to dimension mooring lines for station-keeping, and are based on the work performed to certify synthetic fibre ropes for these applications (Del Vecchio C J M, 1992, Light-weight materials for deep water moorings, PhD thesis University of Reading; Francois M, Davies P, 2008, Characterization of polyester mooring lines, OMAE 2008-57136). Tests to determine quasi-dynamic stiffness are carried out as defined in both international standards (ISO 18692, 2007, Fibre ropes for offshore station keeping Polyester) and classification society rules (Bureau Veritas, 2007, Certification of fibre ropes for deep water offshore services, NI432R01).

(32) The loading scheme for quasi-dynamic measurement is shown in FIG. 7. The abscissa is time in the unit of second (s) and the ordinate is the applied load in the unit of kN. The mean load applied is 10%, 20%, 30% and 40% of the breaking load (BL) of the wire rope. The quasi-dynamic stiffness values of hybrid rope (A) and full steel rope (B) are shown and compared in FIG. 8. The quasi-dynamic stiffness of both ropes increases significantly with increasing mean load over the applied range of loads (10-40% of BL). The quasi-dynamic stiffness of hybrid rope (A) is 17-26% lower than the full steel rope (B). However, the advantage of hybrid rope over full steel rope appears when taking the weight into account. Specific stiffness is defined as the ratio of stiffness to linear weight. As shown in FIG. 9, the specific stiffness of hybrid rope (A) is 22-37% higher than that of full steel rope (B) over the tested load range.

(33) In addition, creep over time at constant loads are evaluated in FIG. 10. Creep is defined as wire rope deformation (elongation) under a constant, static loading situation. A 22 mm multi-strand hybrid rope (A) is compared with 13 mm 8-strand full steel rope (C) and 13 mm 8-strand hybrid rope (D). The applied load on 22 mm multi-strand hybrid rope (A) is 50% BL while on 13 mm 8-strand full steel rope (C) and 13 mm 8-strand hybrid rope (D) is 40% BL. The temperatures of wire rope were kept at about 50 during 10 days measurement. The creep was measured as a change of strain (%) over time (h). As shown in FIG. 10, hybrid rope (A) presents a bigger strain than full steel rope (C) at the moment of applying load which is as expected from a fiber core rope. However, over time at constant load, hybrid rope (A) shows a similar strain change compared to full steel wire rope (C). Compared with 8-strand hybrid rope (D), more load is applied on the invention multi-strand hybrid rope (A) (50% BL vs. 40% BL). In addition, the relative cross-section area of core is bigger in multi-strand hybrid rope (A). Even with these facts, the creep rate of multi-strand rope (A) is significantly low. Therefore, creep does not become problematic over time for the invention hybrid rope.

LIST OF REFERENCES

(34) 10 composite cable 12 synthetic core 14 metal jacket 16 wire 20 conically shaped space of the socket 30 hybrid rope terminated at its end by a socket 40 hybrid rope 1 42 fiber core 44 first metallic wirelike member 46 second metallic wirelike member 50 hybrid rope 2 52 fiber core 54 first metallic wirelike member 56 second metallic wirelike member 60 hybrid rope 3 62 fiber core 63 thermoplastic layer 64 first metallic wirelike member 66 second metallic wirelike member 68 thermoplastic protection layer