Rope

Abstract

The instant invention is a rope. This rope includes a blend of filaments including a first filament, and a second filament. The second filament is fluorocarbon polymer filament.

Description

FIELD OF INVENTION

The instant application relates to a rope for various types of applications including, but not limited to, heavy lifting or mooring applications, such as marine, oceanographic, offshore oil and gas, seismic, and industrial applications.

BACKGROUND OF THE INVENTION

The use of ropes in various applications is widely known. Generally, a rope may be a stout cord made of strands of natural or artificial fibers twisted or braided together, or in the alternative, a rope may be a cord having a wire core with fiber strands braided around it.

Different factors must be considered in order to prevent rope failure. These factors include, but are not limited to, rope construction methods, fiber selections, and service conditions. Rope failure may be caused by different damage mechanism, e.g. frictional heat generated within the rope, or self-abrasion. The frictional heat generated within a rope may be caused by the bending mechanism; or in the alternative, it may be cause by the rope rubbing against a drum, a pulley, or a sheave. The frictional heat generated within a rope can be great enough to cause a catastrophic failure of the rope. This problem is particularly evident when the fiber material looses a substantial amount of strength, i.e. becoming susceptible to creep rupture, when heated above ambient temperature.

Different techniques have been employed to improve rope strength. For example, jacketing the subropes(or strands) is employed to reduce self-abrasion since it is widely known that the primary occurrence of self-abrasion is at the intersection between the subropes. Jacketing refers to the placement of a sleeve material (e.g., woven or braided fabric) over the subrope, so that the jacket is sacrificed to save the subrope. These jackets, however, add to the overall diameter, weight, and cost of the rope without any appreciable increase in the rope's strength. The larger size is obviously undesirable because it would require larger drums, pulleys, or sheaves to handle the jacketed rope. In addition, rope jackets make visual inspection of the rope core fibers problematic because the jacket hides the core fibers. Therefore, while this solution may be viable, it is considered unsatisfactory.

U.S. Pat. No. 5,931,076 discloses a method for construction of a large diameter braided rope. The rope is formed of high strength, low elongation synthetic fibers that are twisted together at a twist factor in the range from about 125 to about 145 to form a plurality of comparatively small diameter yarns. The small diameter twisted yarns are then braided together at a pick multiplier in the range from about 1.0 to about 2.0 so as to form a plurality of braided strands, and the strands, in turn, are braided together with a pick multiplier of about 2.0 to about 3.6 so as to form the large diameter braided rope.

U.S. Pat. No. 5,901,632 discloses a method for forming a braided rope. Twisted yarns are first braided together to form braided strands, and the braided strands are then braided together to form a rope.

U.S. Pat. No. 4,534,163 discloses a synthetic rope or cable. In making the synthetic fiber rope or cable, a plurality of filaments are brought in parallel into a core and compacted by a plurality of ribbons or tapes wound about the core under tension in opposite directions to form a uniform jacket that is torsionally stable. An outer sheath which may be urethane or other plastic material is applied to the jacket under sufficient pressure to penetrate the jacket but not the core, and then the urethane is cured. This rope or cable has a core of substantially parallel filaments free to move within the jacket of ribbons wound about the core and penetrated with urethane or other plastic material.

U.S. Patent Application publication No. US 2004/0069132 discloses a large diameter rope having improved fatigue life on a sheave, pulley, or drum. The rope includes a blend of HMPE filaments and liquid crystal polymer filaments selected from the group of lyotropic polymer filaments and thermoplastic polymer filaments. The rope may be constructed as a braided rope, a wire-lay rope, or a parallel core rope.

Despite the extensive levels of activity and research efforts in developing ropes with high strength for different applications, there is a still a need for a new rope with high strength, low risk of failure, and free of jackets on the subropes or completed ropes. Additionally, the new rope should be suitable for a wide range of applications.

SUMMARY OF THE INVENTION

The instant invention is a rope. This rope includes a blend of filaments including a first filament, and a second filament. The second filament is a fluorocarbon polymer filament.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in the drawings a form that is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIG. 1A is an elevational view of a length of a first embodiment of a rope made according to the present invention;

FIG. 1B is an elevational view of a length of a twisted yarn of the rope of FIG. 1A;

FIG. 1C is an elevational view of a length of a braided strand of the rope of FIG. 1A;

FIG. 1D is an exploded view of an end portion of the first embodiment of the rope of FIG. 1A, schematically illustrating the manner in which twisted yarns are braided together to form braided strands which are then braided together to form the rope of FIG. 1A;

FIG. 2A is an elevational view of a length of a second embodiment of a rope made according to the present invention;

FIG. 2B is an elevational view of a length of a twisted strand of the rope of FIG. 2A;

FIG. 2C is an elevational view of a length of a twisted yarn of the rope of FIG. 2A;

FIG. 2D is an exploded view of an end portion of a second embodiment of a rope made according to the present invention, schematically illustrating the manner in which twisted yarns are twisted together to form twisted strands which are then twisted together to form a rope;

FIG. 3A is an elevational view of a length of a third embodiment of a rope made according to the present invention, schematically illustrating the manner in which the rope is made; and

FIG. 3B is a cross sectional view of the rope of FIG. 3A along the lines 3b-3b.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings wherein like numerals indicate like elements, there is shown, in FIGS. 1A -1D, a first exemplary embodiment of a rope 10 according to the instant invention. This rope 10 includes a blend of filaments 12. Blend of filaments 12 includes a first filament 14, and a second filament 16. Blend of filaments 12 may further include a third filament (not shown).

First filament 14 may be any high strength filament. For example, first filaments 14 may be high modulus polyethylene filaments (“HMPE”) that are spun from ultrahigh molecular weight polyethylene (“UHMWPE”) resin. HMPE filaments are commercially available under the tradename of SPECTRA® from Honeywell Performance Fibers of Colonial Heights, Va., and DYNEEMA® from DSM NV of Heerlen, The Netherlands, and Toyobo Company Ltd. of Osaka, Japan. In the alternative, the first filament 14 may be a liquid crystal polymer (LCP) filament selected from the group consisting of lyotropic polymer filament and thermotropic polymer filament. Lyotropic polymers decompose before melting but form liquid crystals in solution under appropriate conditions (these polymers are solution spun). Lyotropic polymer filaments include, for example, aramid and polyphenylene benzobisoxazole (PBO) fibers. Aramid filaments are commercially available under the tradename KEVLAR® from Dupont of Wilmington, Del., TECHNORA® from Teijin Ltd. of Osaka, Japan, and TWARONO from Teijin Twaron BV of Arnhem, The Netherlands. PBO fibers are commercially available under the tradename ZYLON® from Toyobo Company Ltd. of Osaka, Japan. Thermotropic polymers exhibit liquid crystal formation in melt form. Thermotropic filaments are commercially available under the tradename VECTRAN® from Celanese Advanced Materials, Inc. of Charlotte, N.C. The first filaments 14 may constitute between about 1 to 99 percent volume of the blend 12.

The second filament 16 may be any filament. For example, second filament 16 may be a fluorocarbon polymer. An example of fluorocarbon polymer includes, but is not limited to, poly(tetrafluoroethylene) (“PTFE”). PTFE fibers filaments are commercially available from W. L. Gore & Associates, Inc. of Newark, Del. and Elkton, Md. The second filaments 16 may constitute between about 1 to 40 percent volume of the blend 12.

The third filament (not shown) may be any high strength filament. For example, third filaments may be high modulus polyethylene filaments (“HMPE”) that are spun from ultrahigh molecular weight polyethylene (“UHMWPE”) resin. HMPE filaments are commercially available under the tradename of SPECTRA® from Honeywell Performance Fibers of Colonial Heights, Va., and DYNEEMA® from DSM NV of Heerlen, The Netherlands, and Toyobo Company Ltd. of Osaka, Japan. In the alternative, the third filament (not shown) may be a liquid crystal polymer (LCP) filament selected from the group consisting of lyotropic polymer filament and thermotropic polymer filament. Lyotropic polymers decompose before melting but form liquid crystals in solution under appropriate conditions (these polymers are solution spun). Lyotropic polymer filaments include, for example, aramid and polyphenylene benzobisoxazole (PBO) fibers. Aramid filaments are commercially available under the tradename KEVLAR® from Dupont of Wilmington, Del., TECHNORA® from Teijin Ltd. of Osaka, Japan, and TWARON® from Teijin Twaron BV of Arnhem, The Netherlands. PBO fibers are commercially available under the tradename ZYLON® from Toyobo Company Ltd. of Osaka, Japan. Thermotropic polymers exhibit liquid crystal formation in melt form. Thermotropic filaments are commercially available under the tradename VECTRAN® from Celanese Advanced Materials, Inc. of Charlotte, N.C. The third filaments may constitute between about 1 to 99 percent volume of the blend 12.

Rope 10 may further include a coating. It is believed, but the invention should not be so limited, that the coating improves upon the abrasion resistance of the blend 12. The coating may be any coating. The coating may, for example, be a synthetic polymer based product. For example, the coating may be a polyurethane coating. Rope 10 may have any amount of coating. Coating may be applied to rope 10 via known conventional methods, which includes but is not limited to, impregnating rope 10 with coating by soaking rope 10 in the coating.

Rope 10 may have different rope constructions. For example, rope 10 may have a rope construction selected from the group consisting of a braided rope construction, wire-lay rope construction, and parallel core rope construction.

In the manufacture of the rope 10, well-known techniques for making ropes are used. Such methods are further disclosed in U.S. Pat. Nos. 4,534,163, 5,931,076, and 5,901,632 incorporated herein by reference.

In construction of the first embodiment of rope 10, referring to FIG. 1A-1D, the blend of filaments 12, which includes the first, and second filaments 14, and 16, respectively, is twisted together in a conventional manner to form a twisted yarn 20. The number of the first, and second filaments, 14, and 16 twisted together to form the twisted yarn 20 is not limited. Referring to FIG. 1c, a plurality of twisted yarns 20 is, then in turn, braided together in a conventional manner to from a braided strand 22. The number of twisted yarns 20 braided together to form the strand 22 is not limited. A plurality of braided strands is, subsequently, braided together in a conventional manner to form the rope 10. The number of braided strands 22 to form the rope 10 is not limited.

In an alternative construction of the first embodiment of rope 10, the blend of filaments 12, which includes first filament 14, second filament 16, and third filament (not shown) is twisted together in a conventional manner to form a twisted yarn 20. The number of the first filament 14, second filament 16, and third filament twisted together to form the twisted yarn 20 is not limited. Referring to FIG. 1c, a plurality of twisted yarns 20 is, then in turn, braided together in a conventional manner to from a braided strand 22. The number of twisted yarns 20 braided together to form the strand 22 is not limited. A plurality of braided strands is, subsequently, braided together in a conventional manner to form the rope 10. The number of braided strands 22 to form the rope 10 is not limited.

In construction of the second embodiment of rope 10, referring to FIG. 2A-2D, the blend of filaments 12, which includes the first, and second filaments 14, and 16, respectively, is twisted together in a conventional manner to form a twisted yarn 20a. The number of the first, and second filaments, 14, and 16 twisted together to form the twisted yarn 20 is not limited. A plurality of the twisted yarns 20a is, then in turn, twisted together in a conventional manner to from a twisted strand 22a. The number of twisted yarns 20 twisted together to form the strand 22a is not limited. A plurality of twisted strands 22a is, subsequently, twisted together in a conventional manner to form the rope 10a. The number of twisted strands 22a to form the rope 10a is not limited.

In an alternative construction of the second embodiment of rope 10, the blend of filaments 12, which includes the first filament 14, second filament 16, and third filament (not shown) is twisted together in a conventional manner to form a twisted yarn 20a. The number of the first filament 14, second filament 16, and third filament twisted together to form the twisted yarn 20 is not limited. A plurality of the twisted yarns 20a is, then in turn, twisted together in a conventional manner to from a twisted strand 22a. The number of twisted yarns 20 twisted together to form the strand 22a is not limited. A plurality of twisted strands 22a is, subsequently, twisted together in a conventional manner to form the rope 10a. The number of twisted strands 22a to form the rope 10a is not limited.

In construction of the third embodiment of rope 10, referring to FIG. 3A-3B, the blend of filaments 12, which includes the first, and second filaments 14, and 16, respectively, is aligned in a substantially parallel relation to each other, and then compacted under tension to form a core 24. The number of the first, and second filaments, 14, and 16 aligned and compacted together to form the core 24 is not limited. The Core 24 is, subsequently, covered by a covering 26. The covering 26 may include, but is not limited to, a synthetic polymer based product.

In an alternative construction of the third embodiment of rope 10, the blend of filaments 12, which includes the first filament 14, second filament 16, and third filament (not shown) is aligned in a substantially parallel relation to each other, and then compacted under tension to form a core 24. The number of the first filament 14, second filament 16, and third filament aligned and compacted together to form the core 24 is not limited. The Core 24 is, subsequently, covered by a covering 26. The covering 26 may include, but is not limited to, a synthetic polymer based product.

Rope sample numbers 1-12 were prepared, and evaluated for their bend-over-sheave cycle fatigue (fatigue life). Rope sample 1-12 had the following compositions as shown in Table I. The testing conditions are shown in Table II, and the fatigue life of rope samples 1-12 is shown in Table III.

TABLE I
		Composition
Rope	Rope	Of
Sample No.	Diameter	Rope
1	9 mm	100% Technora T200W
2	9 mm	100% Technora T200W, Polyurethane Coated
3	9 mm	80% Technora T200W/20% poly(tetrafluoroethylene)
		(“PTFE”) composite
4	9 mm	80% Technora T200W/20% poly(tetrafluoroethylene)
		(“PTFE”) Composite, Polyurethane Coated
5	9 mm	100% Vectran T117 - Waxed, Polyurethane Coated
6	9 mm	80% Vectran T117/20% PTFE Composite - Waxed,
		Polyurethane Coated
7	18 mm	50% Ultrahigh Molecular Weight Polyethylene (“UHMWPE”)/
		50% Vectran T97 Composite
8	18 mm	50% UHMWPE/50% Vectran T97 Composite, Polyurethane
		Coated
9	18 mm	45% UHMWPE/45% Vectran T97/10% PTFE Composite
10	18 mm	45% UHMWPE/45% Vectran T97/10% PTFE Composite,
		Polyurethane Coated
11	40 mm	50% UHMWPE/50% Vectran T97 Composite, Polyurethane
		Coated
12	40 mm	45% UHMWPE/45% Vectran T97/10% PTFE Composite,
		Polyurethane Coated

TABLE II
Rope Sample				Cycling
No.	Tension Sheave	Tension	Nominal Stroke	Frequency
1-6	7.2 Inch	3,560 Pounds	24 Inches	600 Cycles Per Hour
	Aluminum
	Sheave
7-10	9 Inch Steel	7,500 Pounds	30 Inches	360 Cycles Per Hour
	Sheave
11-12	46 Inch Steel	60,000 Pounds	120 Inches	360 Cycles Per Hour
	Sheave

TABLE III
Rope Sample No. Bend-Over-Sheave Cycle Fatigue
1               15,951 Cycles
2               18,255 Cycles
3               25,661 Cycles
4               13,214 Cycles
5               3,650 Cycles
6               20,148 Cycles
7               26,852 Cycles
8               12,809 Cycles
9               96,844 Cycles
10              36,486 Cycles
11              8,596 Cycles
12              18,450 Cycles

The present invention may be embodied in other forms without departing from the spirit and the essential attributes thereof, and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicated the scope of the invention.

Claims

1. A rope comprising:

a blend of filaments comprising; a first filament, and a second filament, said second filament being a fluorocarbon polymer filament.

2. The rope according to claim 1, where in said first filament being a high molecular weight polyethylene filament.

3. The rope according to claim 2, wherein said rope further comprising a coating.

4. The rope according to claim 3, wherein said coating being polyurethane.

5. The rope according to claim 2, wherein said blend of filament further comprising a third filament, said third filament being a high strength filament selected from the group consisting of lyotropic polymer filaments and thermotropic polymer filaments.

6. The rope according to claim 1, where in said first filament being a high strength filament selected from the group consisting of lyotropic polymer filaments and thermotropic polymer filaments.

7. The rope according to claim 6, wherein said blend of filament further comprising a third filament, said third filament being a high molecular weight polyethylene filament.

8. The rope according to claims 1, wherein said rope having a rope construction selected from the group consisting of a braided rope construction, wire-lay rope construction, and parallel core rope construction.

9. The rope according to claims 1, wherein said fluorocarbon polymer filament being a poly(tetrafluoroethylene) filament.

10. The rope according to claim 1, wherein said first, and second filaments being twisted together to form a plurality of twisted yarns, said plurality of twisted yarns being braided together to form a plurality of braided strands, and said plurality of strands being braided together to form said rope.

11. The rope according to claim 1, wherein said first, and second filaments being twisted together to form a plurality of twisted yarns, said plurality of twisted yarns being twisted together to form a plurality of twisted strands, and said plurality of strands being twisted together to form said rope.

12. The rope according to claim 1, wherein said first, and second filaments forming a core, and said core being covered by a cover.

13. A method for improving fatigue life of a rope on a sheave, a pulley, or a drum comprising the steps of:

providing a first filament;

providing a second filament, said second filament being poly(tetrafluoroethylene) filament;

twisting said first, and second filaments together thereby forming a plurality of twisted yarns;

braiding said plurality of twisted yarns together thereby forming a plurality of braided strands;

braiding said plurality of twisted strands together thereby forming a rope having an improved fatigue life on a sheave, a pulley, or a drum.

14. The method according to claim 13, wherein said first filament being a high molecular weight polyethylene filament.

15. The method according to claim 14, wherein said method further including the step of providing a third filament subsequent to the step of providing a second filament, and twisting said first, second, and third filaments together thereby forming a plurality of twisted yarns.

16. The method according to claim 15, wherein said third filament being a high strength filament selected from the group consisting of lyotropic polymer filaments and thermotropic polymer filaments.

17. The method according to claim 13, wherein said first filament being a high strength filament selected from the group consisting of lyotropic polymer filaments and thermotropic polymer filaments.

18. The method according to claim 17, wherein said method further including the step of providing a third filament subsequent to the step of providing a second filament, and twisting said first, second, and third filaments together thereby forming a plurality of twisted yarns.

19. The method according to claim 18, wherein said third filament being a high molecular weight polyethylene filament.

20. A method for improving fatigue life of a rope on a sheave, a pulley, or a drum comprising the steps of:

providing a first filament;

providing a second filament, said second filament being a poly(tetrafluoroethylene) filament;

twisting said first, and second filaments together thereby forming a plurality of twisted yarns;

twisting said plurality of twisted yarns together thereby forming a plurality of twisted strands;

twisting said plurality of twisted strands together thereby forming a rope having an improved fatigue life on a sheave, a pulley, or a drum.

21. The method according to claim 20, wherein said first filament being a high molecular weight polyethylene filament.

22. The method according to claim 21, wherein said method further including the step of providing a third filament subsequent to the step of providing a second filament, and twisting said first, second, and third filaments together thereby forming a plurality of twisted yarns.

23. The method according to claim 22, wherein said third filament being a high strength filament selected from the group consisting of lyotropic polymer filaments and thermotropic polymer filaments.

24. The method according to claim 20, wherein said first filament being a high strength filament selected from the group consisting of lyotropic polymer filaments and thermotropic polymer filaments.

25. The method according to claim 24, wherein said method further including the step of providing a third filament subsequent to the step of providing a second filament, and twisting said first, second, and third filaments together thereby forming a plurality of twisted yarns.

26. The method according to claim 25, wherein said third filament being a high molecular weight polyethylene filament.

27. A method for improving fatigue life of a rope on a sheave, a pulley, or a drum comprising the steps of:

providing a first filament;

providing a second filament, said second filament being a poly(tetrafluoroethylene) filament;

aligning said first, and second filaments in a substantially parallel relation to each other;

compacting said aligned first, and second filaments under tension;

thereby forming a core;

providing a cover;

covering said core with said cover;

thereby forming said rope.

28. The method according to claim 27, wherein said first filament being a high molecular weight polyethylene filament.

29. The method according to claim 28, wherein said method further including the step of providing a third filament subsequent to the step of providing a second filament, aligning said first, second, and third filaments in a substantially parallel relation to each other, and compacting said aligned first, second, and third filaments under tension.

30. The method according to claim 29, wherein said third filament being a high strength filament selected from the group consisting of lyotropic polymer filaments and thermotropic polymer filaments.

31. The method according to claim 27, wherein said first filament being a high strength filament selected from the group consisting of lyotropic polymer filaments and thermotropic polymer filaments.

32. The method according to claim 31, wherein said method further including the step of providing a third filament subsequent to the step of providing a second filament, aligning said first, second, and third filaments in a substantially parallel relation to each other, and compacting said aligned first, second, and third filaments under tension.

33. The method according to claim 32, wherein said third filament being a high molecular weight polyethylene filament.