Flexible cable with extended lifespan, and method for manufacturing flexible cable

Abstract

The flexible cable 1 is manufactured by endlessly winding at least one thread 6 around two thimbles 2,4. The thread 6 comprises aramid or similar fiber. Each thimble 2,4 holds a stack 9 of multiple layers 10 of turns of thread 6. The cable 1 comprises a resin 12 provided on at least one of the first and second thimbles only to interconnect the layers of turns of thread and to maintain the tangential orientation of the respective thread layers 10 relative to each other when the flexible endlessly wound cable is subjected to a load. The cable has optional carbon fiber sheets 18,20 between preselected layers of thread in the thimbles.

Description

Detailed Description of the Invention

[0001] The present invention relates to a flexible cable as described in the preamble of claim 1 and a method for manufacturing a flexible cable as described in the preamble of claim 13. This type of cable can be used in various types of industries including, but not limited to, offshore mining and the hoisting of heavy objects, as well as construction. Offshore, this type of cable can be used as a mooring cable for floating oil exploration or production facilities, or for floating wind turbines. Specifically, this type of cable can be used as a so-called tendon or tether to fix a (semi-submersible) floating object under tension to the seabed or ocean floor to form a tension leg platform (TLP) as a foundation for a wind turbine or other facilities. In mining and the hoisting of heavy objects, such a cable can be used to suspend a crane. In construction, such a cable can be used as a tension member in a bridge or a roof suspension cable.

[0002] The concept of an endless winding cable or rope is described in the English version of Wikipedia's page on ropes as follows: "An endless winding rope is manufactured by winding a single strand of high-performance yarn around two extreme ends until the desired breaking strength or stiffness is reached. (Often specified as a cable to distinguish it from a braided or twisted structure.) This type of rope has advantages such as no structural elongation, similar to the case of the above-described structure."

[0003] Endless wound cables are known from WO2017 / 086778 (WO'778). This document discloses a cable manufactured by winding a main thread around two thimbles that form two end fittings in the final cable. To reduce cable wear, WO'778 proposes providing a stack of layers of a second type of fiber on the support surface of the thimbles. The stack of the second type of fiber avoids direct contact between the main thread and the support surface. As a result, the main thread is not worn down by the movement of the main thread relative to the support surface. The properties of the second type of fiber are selected such that their wear is less than that of the main thread.

[0004] While the solution in WO2017 / 086778 (WO'778) offered an improvement over the then-currently known conventional technology, there continued to be a need for further improvements in cable strength and lifespan.

[0005] The present invention aims to provide a cable with higher strength and / or a longer lifespan than WO'778 cables, or at least an alternative. This objective is achieved by the cable described in claim 1.

[0006] The flexible cable is manufactured by endlessly winding at least one thread around two thimbles and comprises a first thimble, a second thimble, and at least one thread. The thread is a highly elastic synthetic or natural fiber selected from a list including aramid fibers, polyarylate fibers, PBO fibers, and basalt fibers, having a Young's modulus of at least 55 GPa, specifically at least 100 GPa, preferably at least 110 GPa, and more preferably at least 120 GPa, as specified by ASTM D7269. The first and second thimbles are provided at both ends of the cable. At least one thread extends from the first thimble to the second thimble, around the second thimble, extends from the second thimble to the first thimble, and around the first thimble, so that the thread forms a winding around the first and second thimbles, with each thimble holding a stack of multiple layers of the thread winding. The adhesive is provided on at least one of the first and second thimbles and connects at least two of the multiple layers of yarn windings within each stack of the first or second thimble to each other in order to maintain the tangential orientation of each yarn layer relative to one another when the flexible endless winding cable is subjected to load.

[0007] This invention is based on the discovery that a breakage mechanism occurs when a flexible, endlessly wound cable is wound for transport. In its wound state, the cable is subjected to a load such that the fibers on the radially inner side of the roll are compressed, while the fibers on the radially outer side of the roll are stressed. This localized difference in load results in a slight misalignment of the layers of yarn within one or both thimble stacks relative to each other. This misalignment may remain, at least partially, after the cable is unwound, resulting in uneven length and, consequently, uneven load on the fibers when the cable is subjected to load during use. Since the claimed fiber type has a relatively high Young's modulus, the difference in length results in portions of yarn receiving less load than designed and other portions receiving more load than designed, leading to premature breakage in the portions receiving higher loads.

[0008] Connecting at least two layers together with adhesive prevents relative movement of these layers when the cable is wound or otherwise placed in a curved configuration, thereby preventing uneven loading of the threads on one side of the cable onto the threads on the other side. It is sufficient to apply adhesive only to a portion of the circumference of the thimble that supports the threads, which prevents slippage caused by winding the cable.

[0009] In one embodiment, the adhesive is spread only to a portion of the circumference, specifically, the portion centered on the longitudinal axis of the cable. This embodiment reduces the cost of applying the adhesive to a portion, specifically the center, compared to applying the adhesive to the entire circumference, not only from a material standpoint but also from a work standpoint.

[0010] For example, the adhesive spreads over less than 50% of the circumference, for example, less than 25% of the circumference, specifically less than 10% of the circumference. The adhesive spreads over more than 1% of the circumference, specifically more than 2% of the circumference, and more specifically more than 5% of the circumference. Preferably, the adhesive spreads over one-third to one-quarter of the circumference.

[0011] In another embodiment, the adhesive is spread over the entire circumference of the thimble supporting the thread. The present invention according to this embodiment is based on the finding that conventional cables break prematurely due to micro-abrasion between the layers of thread at the end fitting. This is caused by one or more of the following mechanisms: The length of the thread in the thimble is longer in the outer layers of thread windings than in the inner layers of windings. While this difference in length is small in absolute terms from one layer to the next, the amount of elongation corresponds to the length of the thread due to the predetermined Young's modulus and cross-sectional area of ​​the thread, as well as the tension in the thread, so the difference in length results in different thread elongation under load. When the cable is subjected to load cycles by repeatedly increasing and decreasing tensile loads applied to the thimble, the difference in elongation results in reciprocal movement of each layer of thread windings relative to adjacent layers. This movement causes micro-abrasion of the thread. A further failure mechanism, further triggered by the load cycle, is that the longitudinal stress in each layer of yarn is transmitted thimblely as radially inward pressure through the intermediate layer of yarn, resulting in slight compression of the yarn stack. This inward pressure leads to slight compression of the intermediate layer. An uncompressed yarn stack may contain 50% air, which may be compressed to a minimum of 35% air. This compression results in reciprocal motion of the outer yarn layer against the inner yarn layer, leading to micro-wear.

[0012] According to the present invention, at least two of the multiple layers of yarn windings within a stack of at least one yarn of the thimble are connected to each other by adhesive such that each layer maintains a tangential orientation to each other when the flexible endless winding cable is subjected to the maximum design load of the flexible endless winding cable. This prevents relative movement of these layers and, consequently, wear of the yarn in the layers within the stack.

[0013] The present invention provides a solution for reducing minute wear in endlessly wound cables made of yarns comprising highly elastic synthetic or natural fibers having a Young's modulus of at least 55 GPa. In filing this application, the applicant has used and / or tested yarns comprising aramid fibers, polyarylate fibers, PBO fibers, or basalt fibers for such endlessly wound cables. All endless cables using such tested yarns exhibit extended lifespan, or more than 10 to 20 times that of similar cables, without the application of the present invention. This application is intended to provide further protection, by at least equivalent means, to endlessly wound cables made of yarns made of fibers having properties equivalent to the aforementioned fibers in terms of strength, Young's modulus, and fiber surface roughness, and thus subject to the same or similar failure mechanisms.

[0014] Additional layers of yarn may also be provided with adhesive to connect the yarns of such layers together within each stack. Specifically, almost all layers in at least one of the thimbles are connected by adhesive.

[0015] The adhesive is applied to and cured in each layer of thread in only one or all of the thimbles, and not between the threads along the entire length of the cable. Applying and curing adhesive between the threads along the entire length of the cable would result in a rigid rod instead of a flexible cable. The expression that the adhesive is applied to only at least one of the first and second thimbles is to be interpreted appropriately within the context of this specification.

[0016] Preferred embodiments are defined in the dependent claims. In one embodiment, the adhesive comprises a resin, specifically an epoxy resin. The resin provides another beneficial effect by maintaining the layers of yarn windings within the laminated structure in their radial positions relative to the center of the thimble. Each layer transmits a portion of the load on the cable to the associated thimble. In the cable described in WO'778, this load is transmitted as pressure to the layers of yarn below, the layers between the associated layer and the supporting surface of the thimble. High-performance fibers, such as aramid fibers, release a portion of their load-bearing capacity when subjected to lateral loads, so this pressure can lead to a reduction in the load-bearing capacity of the yarn fibers. By applying the resin, at least a portion of the load is transmitted through the resin instead of the yarn below, resulting in less pressure, and consequently, less or even complete elimination of abrasion. Specifically, the resin acts as a matrix. Another beneficial effect of the resin is the reduction of localized transmitted loads on the yarns, since the yarn surfaces are rough at a micro-level, and the transmitted load is transmitted to adjacent yarns via the resin rather than primarily through protrusions on the rough yarn surface.

[0017] It should be noted that US2013 / 0000087 (US'087) discloses a cable end connector for a cable constructed from multiple twisted filaments. The cable end connector comprises an end component for mounting or supporting the cable. The end component is fastened to one end of the cable and is manufactured from a castable, curable material, such as synthetic resin, and connects to the filaments only in a morphologically fitted form by being cast around or molded on, without any additional mechanical connection elements. The filaments are unraveled from the original twisted assembly in the area of ​​the end component and distributed essentially uniformly. The end component is manufactured by injection molding of synthetic fibers in a mold, and the filaments are embedded and cast in a morphologically fitted form around the material of the end component under prestress. The synthetic resin in US'087 thus forms the cable end fitting. If the synthetic resin were to break, or if the embedded filaments were to detach from the resin, the entire end fitting would be damaged. In contrast, the end fitting of the present invention is manufactured with a thimble having an uninterrupted winding of thread, and the resin or any other adhesive only serves to prevent movement between the layers of thread. If the adhesive fails, the end fitting of the present invention will still function like the end fitting in WO'778, and although it will suffer from long-term wear, it will not fail immediately like the cable end fitting in US'087.

[0018] In one embodiment, adhesive is provided in the thread layers within both thimbles. In an embodiment having more than two thimbles, adhesive is provided in all thimbles. In another embodiment, adhesive is provided on all the thread layers in at least one of the thimbles.

[0019] In one embodiment, stacks of different types of fibers, specifically sheets of such fibers, are placed on the support surface of at least one thimble before the yarn is wound, as disclosed in more detail in WO2017 / 086778.

[0020] In one embodiment, the aramid fiber is a para-aramid fiber. This type of fiber is very strong compared to metals and most other types of synthetic fibers. In one embodiment, the cable comprises at least a first sheet provided between two layers of one of the stacks of yarn windings in a stack of yarn windings, which is located between two layers of one of the first and second thimbles. Adding the first sheet between adjacent yarn winding layers of the thimble improves the rigidity of the stack of layers, thereby minimizing relative movement between the yarn winding layers in the thimble.

[0021] In one embodiment, at least the first sheet is one of a plurality of sheets, each sheet being separately located between two layers of one of the first and second thimble stacks in a stack of yarn windings. This configuration with multiple sheets distributes the stress required to give sufficient rigidity across the multiple sheets to the stack of yarn layers with the sheets sandwiched in between.

[0022] In one embodiment, each of the thread stacks of both thimbles is provided with at least one sheet between the two layers of thread. In one embodiment, at least the first sheet comprises a unidirectional fabric. Such a fabric provides maximum strength and rigidity in the direction of the fibers. Specifically, the direction of the fibers in the unidirectional fabric is set substantially parallel to the direction of the yarn.

[0023] In one embodiment, the stiffness of at least the first sheet is greater than the stiffness of the thread. This improves the effect of restraining the sheet on the thread. In one embodiment, at least the first sheet comprises sheet fibers, the Young's modulus of which is higher than that of the high-elasticity synthetic fibers of the yarn, specifically at least twice as high.

[0024] In one embodiment, at least the first sheet comprises fibers selected from a list consisting of carbon fibers, PBO (polybenzobisoxazole) fibers, and high-elasticity aramid fibers. In one embodiment, at least the first sheet comprises more than one type of fiber, and at least one of these fiber types is selected from the list consisting of carbon fiber, PBO fiber, and high modulus aramid fiber.

[0025] In another aspect, the present invention relates to a method for manufacturing a flexible endless winding cable according to claim 13, specifically, to a method for manufacturing a flexible endless winding cable according to any one of claims 1 to 12, or an inventive flexible endless winding cable as defined in the preceding paragraph.

[0026] By applying an adhesive at least once to at least one of the singles, at least two layers of yarn windings in each single are connected to each other. As a result, the method according to the present invention provides the endless winding cable with the beneficial properties as described above. The adhesive is not applied and / or not cured at the endless winding cable extending between the first single and the second single so that the flexible endless winding cable remains flexible between the first single and the second single.

[0027] Specifically, one step of applying the adhesive results in connecting more than two layers of yarn windings. Due to the tension of the yarn during winding, excess adhesive is pressed out from the layer of yarn windings initially applied to the further layer. Adding more adhesive than required to connect two layers of yarn windings results in connecting more layers of yarn windings than the step of adding the adhesive.

[0028] Preferred method steps are defined in the dependent claims. In one embodiment, the method comprises the step of placing at least the first sheet on one of the layers of yarn windings in one of the first and second singles after providing at least one layer of yarn windings and before providing the next layer of yarn windings.

[0029] In one embodiment, the method comprises the step of placing a further sheet on another of the layers of yarn windings in one of the first and second thimbles. In one embodiment, the step of adding adhesive to the yarn winding layer in at least one of the thimbles is repeated at least twice during the manufacture of the flexible endless winding cable.

[0030] In one embodiment, the step of applying adhesive to the layers of yarn windings in at least one of the thimbles is repeated after at least one of the thimbles has been provided with n layers of yarn windings, where n is an integer less than 15, specifically less than 10, specifically less than 5, and more specifically less than 2. This allows for precise administration of the required amount of adhesive. In one embodiment, n is greater than 2. Preferably, n is selected from the range of 5 to 10.

[0031] The present invention, its effects, and advantages will be described in more detail based on the schematic diagram. [Brief explanation of the drawing]

[0032] [Figure 1] This shows the end of the cable according to the present invention. [Figure 2] Figure 4 shows a partially disassembled section II-II. [Figure 3] Figure 2 shows a magnified view of the details. [Figure 4] Figure 1 shows a top view of the cable. [Figure 5] Figure 4 shows the cross-section VV. [Figure 6] Figure 4 shows the cross-section VI-VI. [Modes for carrying out the invention]

[0033] Figures 1-6 show a flexible cable according to the present invention, which is shown in its entirety by reference numeral 1. The cable 1 has a first end fitting 3 with a first thimble 2, a second end fitting 5 with a second thimble 4, and a plurality of threads 6. The first thimble 2 and the second thimble 4 are made of stainless steel and are provided at both ends of the cable 1, each having a center 7. The plurality of threads 6, in this embodiment, are ten (10) threads 6, all of which extend from the first thimble to the second thimble and around the second thimble 4, and extend from the second thimble 4 to the first thimble 2 and around the first thimble 2. In this way, each of the plurality of threads 6 forms a semi-continuous loop around the first and second thimbles. This loop is repeated multiple times, 950 times in this embodiment. Thus, each of the threads 6 forms 950 turns, resulting in a total of 9500 turns of thread 6. Cables manufactured in this manner are generally referred to as endless winding cables. It should be noted that the diagram is only schematic, and the actual (relative) dimensions of the cable may differ from those shown. Specifically, the cable according to the present invention can be several hundred meters long, or even exceed 1,000 meters, so the length of the cable is much longer than that proposed in Figure 4.

[0034] The yarn 6 in this embodiment is made of aramid fiber, and in this embodiment, it is made of para-aramid fiber having a density of 3220 dtex and a Young's modulus of 112 GPa. These yarns are sold by Teijin Aramid Co., Ltd. under the name Twaron® D2200.

[0035] Figure 2 shows a cross-sectional view of the thimble 2 having a support surface 8. The thimble 2 holds a stack 9 having multiple layers 10 of windings 6 of yarn 6. This is shown in more detail in Figure 3, which is a considerably enlarged schematic of five (5) layers 10 of windings 6 of yarn 6. In the upper part of Figure 2, for clarity, the stack 9 is shown in an exploded view. In reality, the entire stack 9 is held within the first thimble 2, as shown in the lower part of Figure 2. The second thimble 4 is not shown in detail as it holds the same number of layers of windings 6 of yarn in a similar manner.

[0036] Multiple layers of yarn 10 in one or both of the end fittings 3, 5 of cable 1 are connected to each other by an adhesive, in this embodiment, epoxy resin 12. In this embodiment, epoxy resin 12 is provided in each end fitting 3, 5 to connect all layers 10 of the yarn 6 windings in the stack of each thimble 2, 4 to each other, and to maintain the tangential direction of each layer of yarn 10 relative to each other when the flexible endless winding cable is subjected to load.

[0037] The cable 1 of this embodiment includes a plurality of sheets 14, 16, 18, and 20 on the end fittings 3 and 5. The first sheet 14 and the second sheet 16 are provided within the stack 9 of the layers 10 of the yarn 6 windings in the first thimble 2. The third sheet 18 and the fourth sheet 20 are provided within the stack 9 of the layers 10 of the yarn 6 windings in the second thimble 4. Each of the plurality of sheets 14, 16, 18, and 20 is provided separately between two layers of the associated stack 9. The sheets 14, 16, 18, and 20 of this embodiment are made of unidirectional carbon fiber fabric.

[0038] The epoxy resin 12 interconnects the layers 10 of the yarn 6 with the sheets 14, 16, 18, and 20. The sheets improve the rigidity of the stack 9 of each thimble 2, 4, reducing the movement of the stack as a whole, and also reducing the relative movement of the layers 10 of the yarn 9.

[0039] The cable cover 28 extends around the cable 1 from the first thimble 2 to the second thimble 4, and bundles all the windings 6 of yarn extending between the first thimble 2 and the second thimble 4 into a single compact bundle 30 at the middle section 32 of the cable 1. The middle section 32 in this embodiment is shown to be relatively short compared to the total length of the cable 1. In most embodiments, the middle section will be the longest part of the cable. In this embodiment, the cable cover 28 also covers the windings 6 of yarn at the end fittings 3,5. The cable cover 28 creates bundles 33,34 of yarn 6 windings extending from each thimble 2,4 to the middle section 32.

[0040] Figure 5 shows that the cable 1 in the intermediate section 32, that is, the cable 1 between the end fittings 3 and 5, remains flexible because it is formed by winding the threads 6 without the presence of epoxy resin 12 or any other adhesive between the threads 6.

[0041] Figure 6 is a schematic longitudinal section through the end fitting 5. A longitudinal section through the end fitting 3 is similar in this embodiment and is therefore not shown in detail. The inner and outer contours 40 and 42 of the converging portion 34 of the bundle of yarn windings 6 engage with the thimble 4, and the inner and outer contours 40 and 42 are shown to wrap around the thimble 4. Since the yarn windings 6 are bundled at the middle portion 32, they are divided into two and branch toward the thimble 4, so in this embodiment, the yarn windings 6 engage with the support surface 8 of the thimble 4 at an angle α of approximately 220°. The sheets 18,20 extend around the thimble 4 over at least the same angle α and further across the entire width of the support surface 8. In this embodiment, the sheets 18,20 extend from the thimbles 2,4 through the converging portions 33,34 toward the middle portion 32 so as to increase the surface area for bonding the sheets 18,20 to the layer 10 of yarn windings 6 with epoxy resin 12. Since sheets 18 and 20 do not extend within the intermediate portion 32, the elasticity of the intermediate portion 32 is not affected.

[0042] The region of the support surface 8 that supports the thread 6 is referred to as the support region 44. The support region 44 extends to an angle α, as shown by the dashed line in Figure 6. Generally, adhesive is applied to a portion 46 of the support region 44. In a preferred embodiment, the portion 46 is substantially the entire support region 44. This interconnects the threads 6 throughout the entire support region 44, eliminating movement of the threads 6 relative to each other and thus preventing fiber wear that would lead to premature failure of each cable 1.

[0043] In an alternative embodiment, the adhesive is present in further portions of each end fitting, specifically, within the entire end fitting. In an alternative embodiment, the adhesive covers less than half of the support area 44, for example, one-third or one-quarter of the support area 44, as shown in Figure 14. The portion 46 to which the adhesive is applied is centered on the longitudinal axis 48 of the cable 1.

[0044] The adhesive connects at least two of the multiple layers 10 of the yarn 6, and in a preferred embodiment, substantially all of the layers of the yarn are connected by the adhesive. Connecting substantially all of the layers of the yarn winding results in a better extension of life than connecting only two layers. In the context of this specification, substantially all of the layers of the yarn winding is interpreted as at least 80% of the layers, more specifically at least 90% of the layers, and more specifically at least 95% of the layers.

[0045] In this embodiment, adhesive is not applied to the portion of the support surface 8 that does not support the winding of the thread 6, i.e., the remaining angle (360°-α), for example, the remaining 140° in the example of Figure 6, which is the unsupported region.

[0046] The flexible cable according to the present invention has been tested and did not break even after more than 9 million load cycles. Several tests have shown that the present invention increases the lifespan, measured by the number of load cycles, by 30 to 50 times.

[0047] An embodiment of a method for manufacturing a flexible endless winding cable according to the present invention, for example, one of the cables disclosed above, is: A step of arranging a first thimble and a second thimble at a predetermined distance from each other, wherein this distance corresponds to the required cable length. The process of providing 10 para-aramid threads, The process involves passing 10 threads from the first thimble to the second thimble, wrapping them halfway around the second thimble, returning them to the first thimble, and then wrapping them halfway around the first thimble again. The process of applying adhesive to the layers of thread winding in the thimble, The process involves repeating the step of winding 10 threads around the first and second thimbles until a predetermined number of thread winding layers are provided on both the first and second thimbles, A step of placing a first unidirectional carbon fiber sheet on one of the layers of yarn windings in the first thimble, A step of placing a second unidirectional carbon fiber sheet on one of the layers of yarn winding in the second thimble, The process involves applying additional adhesive to the layers of thread winding in the thimble, The process of winding 10 threads around the first and second thimbles on the first and second sheets is repeated until a second predetermined number of layers of thread windings are provided on both the first and second thimbles, The process involves placing an additional sheet on one of the layers of yarn winding in the first thimble, A step of placing a second additional sheet on one of the layers of yarn windings in the second thimble, The process involves applying additional adhesive to the layers of thread winding in the thimble, A process of winding 10 threads around the first and second thimbles until a third predetermined number of thread winding layers are provided on both the first and second thimbles, wherein the first, second and third predetermined numbers of thread winding layers together correspond to the required cable thickness. The process involves curing an adhesive so that when a flexible endless-winding cable is subjected to a load, the layers of the winding maintain a tangential orientation relative to each other. It is equipped with.

[0048] In this embodiment, the adhesive is not applied to all layers, but rather applied in sufficient quantities each time to spread through adjacent layers and sheets. As a result, in the final product, the adhesive is present between all layers and between layers and sheets before the adhesive hardens.

[0049] In this embodiment, the adhesive is an epoxy resin. In this embodiment, the epoxy resin is a thermosetting polymer that is cured by firing the first and second thimbles.

[0050] In this embodiment, the first and second thimbles are made of stainless steel. In an alternative embodiment, the adhesive is applied after all layers of the yarn windings have been fitted into the thimbles, that is, after a complete stack of layers has been formed in each thimble. The adhesive penetrates between the yarn windings of the layers and through the sheet, spreading throughout the complete stack.

[0051] Apparatus suitable for a method of manufacturing endlessly wound cables is described in WO2017 / 099589 and WO2017 / 086778 by the same applicant. Several modifications are possible within the scope of the appended claims. Features of the preferred embodiments described above may be replaced by any other features within the scope of the appended claims, e.g., other embodiments and features described in the following paragraphs. Features of the product disclosed in connection with the method are preferred features of the flexible cable, and vice versa.

[0052] The cable according to the present invention may be manufactured with more than 10 or fewer than 10 threads, for example, one thread, two threads, or at least five threads. Specifically, the cable is manufactured with at least 12 or 24 threads. The total number of thread turns, i.e., the number of thread turns per layer and the number of layers, depends on the required strength of the cable, the strength of the individual threads, and the required safety margin. The number of layers depends on the required number of thread turns and the available width in the thimble that yields the maximum number of thread turns in the width direction. Specifically, each thread forms at least 1000 turns, more specifically, more than 5000 turns.

[0053] Various types of yarns, such as PBO (polybenzobisoxazole sold by Toyobo Co., Ltd. under the name Zylon), polyarylate fibers (sold by Kuraray Co., Ltd. under the name Vectran), paraaramid yarns sold under the names Twaron (registered trademark of Teijin Aramid BV) and Kevlar (registered trademark of Eldu Pont de Nemours and Company), with densities of 1610 dtex, 4830 dtex, 6440 dtex, 16100 dtex, or 17000 dtex, as well as higher, lower, and intermediate densities, with or without coating, paracopolyamide yarns sold under the name Technora (registered trademark of Teijin Aramid BV), and yarns made from fibers having similar properties may also be used within the scope of the present invention. Examples of paraaramid yarns include Twaron 2100 with a Young's modulus of 65 GPa and Twaron 3200 with a Young's modulus of 138 GPa. The type of fiber for which the present invention provides a solution is relatively abrasion-prone compared to other fiber types such as UHMWPE or nylon fibers, due to its relatively high surface roughness. Specifically, basalt fiber yarn is suitable for the endless winding cable according to the present invention. An example is basalt yarn with 24,000 dtex. While the breaking load, and specifically its high Young's modulus, makes such yarn suitable for endless winding cables, the present invention solves the problem of abrasion in end fittings caused by the relatively high roughness of the fiber.

[0054] In one embodiment, adhesive is provided on the yarn layer in only one of the thimbles. Specifically, in such an embodiment, one thimble differs from the other thimble, for example, in which the adhesive is less useful when the load on the fibers is smaller due to the larger radius and / or width of each thimble.

[0055] In one embodiment, an adhesive is applied to the flexible endless winding cable between thimbles so that the flexible endless winding cable between thimbles remains flexible. The endless winding cable is considered flexible if it can be wound, for example, for transport. Such flexibility exists when different layers of yarn winding in the endless winding cable between thimbles can displace relative to each other in their longitudinal direction. Specifically, the adhesive is applied to the endless winding cable extending between thimbles but not cured, and / or the adhesive is applied to and cured only on a small portion of the endless winding cable in the length and / or width direction, so that the endless winding cable as a whole remains flexible.

[0056] In one embodiment, the flexible cable comprises more than two thimbles. In such an embodiment, at least two thimbles are present at one end of the flexible cable. Two thimbles in one end fitting form a female end fitting, thereby allowing connection to further flexible cables to be constructed by inserting a male end fitting between the thimbles of the female end fitting.

[0057] In one embodiment, a different type of resin may be used, such as a polyester resin, a vinyl ester resin, or a polyamide. Specifically, the resin is a thermosetting polymer.

[0058] In one embodiment, the adhesive is applied to only one of the thimbles. In one embodiment, the adhesive is applied only to one or both thimbles of the end fitting, and not to the converging portion of the yarn winding in the end fitting.

[0059] In this embodiment, the adhesive is not applied to a portion of the support surface that does not support the winding of the thread, i.e., to the non-supported area that extends over the remaining angle (360°-α). In one embodiment, the adhesive is applied during the process of winding the yarn, that is, the adhesive is applied to the top surface of each layer of yarn winding, or to the top surface of every nth layer of yarn winding, where n is an integer greater than or equal to 1 and less than the total number of yarn windings in the stack.

[0060] In one embodiment, the adhesive is cured by adding a curing agent, such as a polyamine curing agent for resins. In another embodiment, the adhesive is cured by irradiation, such as infrared irradiation, ultraviolet irradiation, or microwave irradiation.

[0061] Unidirectional fabrics are generally considered nonwoven fabrics. In practice, the parallel fibers that make up a unidirectional fabric need to be stabilized, for example, by applying warp threads that form a small portion of the fabric. In the context of this specification, a fabric is considered unidirectional if at least 95%, specifically at least 99%, of the weight of the fabric is the weight of the parallel fibers. While unidirectional fabrics are preferred as sheets, in other embodiments the sheet may be a woven sheet, a braided sheet, or a knitted sheet. In alternative embodiments, the sheet may be made of PBO or high-elasticity aramid fibers.

[0062] The present invention achieves advantageous effects by connecting at least two layers of the yarn winding. However, the lifespan is further extended by connecting almost all of the layers of the yarn winding. In the context of this specification, almost all of the layers of the yarn winding are interpreted as at least 80% of the layers, more specifically, at least 90% of the layers, and more specifically, at least 95% of the layers.

[0063] Generally, the winding of the thread engages with a circumferential angle α of the thimble's support surface, where α is greater than 180° and less than 360° of the circumference of the thimble's support surface. In one embodiment, α is greater than 200° of the thimble's support surface, specifically greater than 220°, and more specifically greater than 240°. In one embodiment, α is less than 340° of the thimble's support surface, specifically less than 320°, and more specifically less than 300°.

[0064] The sheet within each end fitting extends at least over the same angle α as the winding of the thread that engages with the support surface. Specifically, the sheet extends from the thimble to the convergence section. Specifically, the sheet extends over at least 20% and up to 100% of the length of the relevant convergence section. Specifically, the sheet extends over at least 50% and more specifically, at least 75% of the length of the relevant convergence section. Specifically, the sheet extends over up to 90% and more specifically, up to 80% of the length of the relevant convergence section.

[0065] In one embodiment, the sheet is not provided on one or both of the thimbles. In one embodiment, one sheet is provided on one or both of the thimbles. In one embodiment, the sheet is provided between every nth and (n+1)th layer of the yarn winding, where n is an integer less than 1 and the number of layers. In one embodiment, n is equal to 10. In another embodiment, n is equal to 6. In yet another embodiment, n is equal to 3.

[0066] In one embodiment, the thimble is made of a plastic material instead of metal, or it is made of a metal other than stainless steel, including, but not limited to, various alloy steels, aluminum alloys, magnesium alloys, and titanium.

[0067] It should be noted that in the above specification, the British spelling is applied to terms such as “fiber,” “mould,” and “centre.” These terms may be replaced with their corresponding American spellings, “fiber,” “mold,” and “center,” without changing the context of this specification.

Claims

1. A flexible endless winding cable, It comprises a first thimble, a second thimble, and at least one thread, The yarn comprises a highly elastic synthetic or natural fiber having a Young's modulus of at least 55 GPa as specified by ASTM D7269. The first thimble and the second thimble are provided at both ends of the cable. The at least one thread extends from the first thimble to the second thimble, around the second thimble, extends from the second thimble to the first thimble, around the first thimble, such that the thread forms windings around the first and second thimbles, and each thimble holds a stack of multiple layers of the thread windings. A flexible endless winding cable wherein an adhesive is provided on at least one of the first and second thimbles, and connects at least two of the plurality of yarn winding layers in each stack of the first or second thimble to each other in order to maintain the tangential direction of each yarn layer relative to one another when the flexible endless winding cable is subjected to a load.

2. A flexible endless winding cable according to claim 1, The aforementioned highly elastic synthetic fiber is a para-aramid fiber, in a flexible, endlessly wound cable.

3. A flexible endless winding cable according to claim 1, A flexible endless winding cable comprising, in the stack of the winding layers of the thread, at least a first sheet provided between two layers of the stack of one of the first and second thimbles.

4. A flexible endless winding cable according to claim 3, A flexible endless winding cable in which at least the first sheet is one of a plurality of sheets, each sheet separately provided in the stack of the yarn winding layers between two layers of one of the first and second thimbles in the stack.

5. A flexible endless winding cable according to claim 3, The above-mentioned flexible endless-winding cable comprises at least the first sheet, which is a unidirectional woven fabric.

6. A flexible endless winding cable according to claim 3, A flexible endless-winding cable in which the rigidity of at least the first sheet is greater than the rigidity of the thread.

7. A flexible endless winding cable according to claim 3, A flexible endless-wound cable comprising at least a first sheet, wherein the Young's modulus of the sheet fibers is higher than that of the high-elasticity synthetic fibers of the yarn.

8. A flexible endless winding cable according to claim 3, A flexible endless-winding cable, wherein at least the first sheet comprises fibers selected from a list consisting of carbon fibers, PBO fibers, and high-elasticity aramid fibers.

9. A flexible endless winding cable according to Claim 1, A flexible endless winding cable, wherein the stacks of the plurality of windings of the thread on each thimble engage with each thimble along a portion of the circumference of each thimble, and the adhesive provided on at least one of the first and second thimbles spreads over at least a portion of the circumference of each first or second thimble.

10. A flexible endless winding cable according to claim 9, The adhesive is spread over the entire circumference of the flexible, endlessly wound cable.

11. A flexible endless winding cable according to claim 9, The adhesive is spread only on the aforementioned portion of the circumference of the flexible, endlessly wound cable.

12. The flexible endless winding cable according to claim 11, The portion of the circumferential part of the flexible endless cable is centered on the longitudinal axis of the flexible endless cable.

13. A flexible endless winding cable according to Claim 1, The adhesive is a flexible, endlessly wound cable containing a resin or epoxy resin.

14. A flexible endless winding cable according to Claim 1, The aforementioned highly elastic synthetic or natural fiber is selected from the group consisting of aramid fibers, polyarylate fibers, PBO fibers, and basalt fibers, in a flexible endless-wound cable.

15. A method for manufacturing a flexible endless winding cable, A step of arranging a first thimble and a second thimble at a predetermined distance from each other, wherein the distance corresponds to the required cable length, and A step of supplying at least one yarn, wherein the yarn comprises a highly elastic synthetic or natural fiber having a Young's modulus of at least 55 GPa as specified by ASTM D7269, The process of passing the at least one thread from the first thimble to the second thimble, turning it half a turn around the second thimble, returning it to the first thimble, and turning it half a turn around the first thimble to wrap it around, The process described above is repeated until a predetermined number of layers of thread winding corresponding to the required cable thickness are provided on both the first thimble and the second thimble. The steps include applying the adhesive to the layer of the yarn winding in at least one of the first and second thimbles, The process involves curing the adhesive to connect at least two of the layers of the yarn windings so that when the flexible endless winding cable is subjected to a load, the layers of the yarn windings in at least one of the first and second thimbles maintain a tangential orientation to each other, and the flexible endless winding cable remains flexible between the first and second thimbles. A method that includes [the following features].

16. The method according to claim 15, A method comprising the step of placing at least a first sheet on one of the layers of yarn winding in one of the first and second thimbles, after providing at least one layer of yarn winding and before providing the next layer of yarn winding.

17. The method according to claim 16, A method comprising the step of placing a further sheet on another of the layers of the yarn winding in one of the first and second thimbles.

18. The method according to claim 16, A method comprising the steps of applying the adhesive so that it penetrates substantially all layers of the yarn winding and the sheet, and curing the adhesive, which results in the connection of all layers of the yarn winding and the sheet such that substantially all layers of the yarn winding maintain a tangential orientation to each other when the flexible endless winding cable is subjected to load.

19. The method according to claim 15, The method comprising the step of applying the adhesive to the layer of the yarn winding in at least one of the first and second thimbles, wherein the step is repeated after n layers of yarn winding have been provided in at least one of the first and second thimbles, and n is an integer less than 10.

20. The method according to claim 15, A method comprising the steps of applying the adhesive such that it penetrates into almost all layers of the yarn winding, and curing the adhesive, which results in the connection of all layers of the yarn winding such that, when the flexible endless winding cable is subjected to a load, almost all layers of the yarn winding maintain a tangential orientation to one another.

21. The method according to claim 15, The method comprising the step of applying the adhesive to the layer of the yarn winding in at least one of the first and second thimbles, wherein the step is repeated after n layers of yarn winding have been provided in at least one of the first and second thimbles, where n is an integer less than 5.

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