Flexible cable with improved service life and method for making flexible cable

Abstract

The flexible cable (1) is produced by annularly winding at least one wire (6) around two sleeves (2, 4). The threads 6 comprise nylon fibers or similar fibers. Each sleeve 2, 4 holds a stack 9 of a plurality of layers 10 of looped wire 6. The cable 1 comprises a resin 12 disposed at at least one of the first sleeve and the second sleeve and cured to interconnect the layers of the looped wires to maintain a tangential orientation of the respective wire layers 10 relative to each other when the annularly wound flexible cable is subjected to a load. Between the sleeves, the wire is substantially free of cured resin 12 such that the cable remains flexible between the sleeves. At the sleeve, the cable has optional carbon fiber flakes 18, 20 between preselected wire layers.

Description

[0001] The present invention relates to a flexible cable according to the preamble of claim 1, and a method for manufacturing a flexible cable according to the preamble of claim 14.

[0002] This type of cable can be used in various industries, including but not limited to the offshore industry, mining and heavy lifting industry, and construction industry. In the offshore industry, this type of cable can be used as a mooring line for floating oil exploration or production facilities or floating wind turbines. In particular, this type of cable can be used as a so-called tendon or mooring line to anchor (semi-submersible) floating objects to the sea or ocean floor under tension, thereby forming a tension leg platform (TLP), which serves as a base for wind turbines or other facilities. In the mining and heavy lifting industry, this cable can be used as a suspension device for cranes. In the construction industry, this cable can be used as a tension member in bridges or a suspension cable for roofs.

[0003] The English Wikipedia page on "Rope" explains the concept of a looped cable or looped rope as follows: "A looped rope is made by winding multiple single strands of high-performance wire around two ends until the desired breaking strength or stiffness is achieved. The advantage of this type of rope (often designated as a cable to distinguish it from braided or twisted constructions) is that there is no structural tension as in the aforementioned structures."

[0004] A circularly wound cable is known from WO-2017 / 086778 (WO'778). This document discloses a cable manufactured by winding a mainline around two sleeves, which form two end fittings in the final cable. To reduce cable abrasion, WO'778 proposes a stack of layers of second-type fibers on the bearing surface of the sleeves. This stacking of second-type fibers avoids direct contact between the mainline and the bearing surface. Therefore, the mainline does not abrade due to movement of the mainline relative to the bearing surface. The properties of the second-type fibers are chosen such that their abrasion is lower than that of the mainline. The mainline in WO'778 is made of high-modulus fibers.

[0005] While the solution offered an improvement over existing technologies known at the time, further improvements to cable performance were still needed.

[0006] The present invention aims to provide a cable with improved performance, or at least an alternative.

[0007] This objective is achieved by the cable according to claim 1.

[0008] A flexible cable is made by looping at least one wire around two sleeves. The flexible cable includes a first sleeve and a second sleeve, and at least one wire. The wire comprises a synthetic or natural fiber with a Young's modulus of 0.1 GPa to 54 GPa, particularly 0.1 GPa to 30 GPa, more preferably 0.1 GPa to 10 GPa, as determined according to ASTM D2256. The first and second sleeves are located at opposite ends of the cable. At least one wire extends from the first sleeve to the second sleeve, turns around the second sleeve, extends from the second sleeve to the first sleeve, and turns around the first sleeve, such that the wire forms a loop around the first and second sleeves, and each sleeve maintains a stack of multiple layers of looped wire. A first adhesive is applied at at least one of the first and second sleeves, and the first adhesive is cured to connect at least two layers of looped wire in the stack of the respective first or second sleeves to maintain the tangential orientation of the respective wire layers relative to each other when the looped flexible cable is under load, while the wire is substantially uncured between the first and second sleeves, so that the cable remains flexible between the first and second sleeves.

[0009] This invention is based on the discovery that a failure mechanism arises when a looped flexible cable is wound up for transport. In the wound state, the cable bears a load because the fibers on the radially outer side of the wound are stressed, while the fibers on the radially inner side are compressed. This localized load difference causes slight displacement of the cable layers relative to each other within the stack of one or both sleeves. After the cable is unwound, this displacement may remain at least partially, resulting in unequal lengths and therefore uneven loads on the fibers when the cable is under load in use. These length differences cause some sections of the cable to bear a smaller load relative to the design load, while others bear a larger load, leading to premature failure of the fibers in the higher-loaded sections.

[0010] Using a first adhesive to bond at least two layers together maintains the tangential orientation of the respective wire layers relative to each other. This prevents relative movement of these layers when the cable is wound up or placed in an arc orientation, and thus prevents the load on one side of the cable from being different from the load on the other side. The first adhesive only needs to be applied to a section of the circumferential portion of the sleeve's support wire, preventing displacement caused by winding the cable.

[0011] Compared to WO'778 cables, the fiber's Young's modulus of 0.1 GPa–54 GPa gives the cables increased elasticity. This increased elasticity allows the cables to absorb energy applied to them by loads such as cyclic loads caused by the effects of waves and / or wind on floating structures.

[0012] In this embodiment, the cured first adhesive extends only on a section of the circumferential portion, specifically centered on the longitudinal axis of the cable. This embodiment reduces costs not only in terms of materials but also in terms of labor, compared to applying the first adhesive to the entire circumferential portion.

[0013] For example, the first adhesive extends across less than 50% of the circumferential portion, such as less than 25% of the circumferential portion, and particularly less than 10% of the circumferential portion. Alternatively, the first adhesive extends across more than 1% of the circumferential portion, particularly more than 2% of the circumferential portion, and even more particularly more than 5% of the circumferential portion. Preferably, the first adhesive extends across one-third to one-quarter of the circumferential portion.

[0014] In another embodiment, the first adhesive extends over the entire circumferential portion of the support wire of the sleeve. The invention according to this embodiment is based on the finding that prior art cables fail prematurely due to minor wear between the wire layers in the end fitting. This is caused by one or more of the following mechanisms: The length of the wire in the outer layer of the coiled wire in the sleeve is greater than the length of the wire in the inner layer of the coiled wire in the sleeve. Although the length difference from one layer to the next is small in absolute terms, this does result in different elongations of the wire under load, since the amount of elongation corresponds to the length of the wire for a given Young's modulus and cross-section, as well as the tension in the wire. When the cable is subjected to load cycles by repeatedly increasing and decreasing tensile loads on the sleeve, the difference in elongation causes each layer of the coiled wire to move back and forth relative to the adjacent layer. This movement causes minor wear on the wire. Another failure mechanism, also caused by load cycles, is that the stack of wire layers is slightly compressed because the longitudinal stress in each of the wire layers is transmitted to the sleeve in a radially inward direction via the intermediate wire layer as pressure. This inwardly directed pressure causes slight compression of the intermediate layer. In its uncompressed state, a stack of looped wires can contain up to 50% air, and it can be compressed to contain at least 35% air. Compression causes the outer wire layer to move back and forth relative to the inner wire layer, and thus produces minute wear.

[0015] According to the invention, at least two layers of looped wires in a stack of wires in at least one of the sleeves are interconnected by a cured first adhesive, such that when the looped flexible cable is subjected to its maximum design load, the respective layers maintain a tangential orientation relative to each other. This prevents relative movement of these layers and, therefore, prevents wear of the wires in the stacked layers.

[0016] This invention provides a solution for reducing minor wear on toroidal cables made of thread comprising synthetic or natural fibers with a Young's modulus of 0.1 GPa to 54 GPa. At the time of filing this application, the applicant has used and / or tested thread for such toroidal cables comprising nylon fibers. The Young's modulus of nylon fibers is typically 1 GPa to 4 GPa. All toroidal cables having this tested thread showed improved service life, or a service life 10 to 20 times greater than that of similar cables not using this invention. This application aims to further protect toroidal cables having threads made of fibers that have similar properties to the aforementioned fibers in terms of strength, Young's modulus, and fiber surface roughness, and therefore have the same or similar failure mechanisms, at least by an equivalent means.

[0017] The additional layers of the wire may also include a first adhesive to bond the wires of these layers together within the respective stack. In particular, substantially all layers of at least one of the sleeves are bonded by the first adhesive.

[0018] A first adhesive is applied and cured in the respective line layer of one or all of the sleeves, while between the two sleeves, the line has essentially no cured first adhesive. Applying and curing the first adhesive also between the sleeves—for example, along the entire length of the cable—results in a rigid rod rather than a flexible cable. Applying and curing the first adhesive only on a small portion of the cable between the two sleeves does not impede the flexibility of the cable. For example, at least 80%, preferably at least 90%, more preferably at least 95%, and for example at least 99%, of the portion of the cable extending between the two sleeves remains without cured first adhesive.

[0019] In some embodiments, the cured first adhesive is applied only at at least one of the first sleeve and the second sleeve, i.e., there is no cured first adhesive between the two sleeves.

[0020] If desired, a second adhesive can be provided in the flexible portion of the cable between the two sleeves, the second adhesive having a lower stiffness than the first adhesive, so that the cable remains flexible between the first and second sleeves.

[0021] The dependent claims define the preferred embodiments.

[0022] In an embodiment, the first adhesive includes a resin, particularly an epoxy resin.

[0023] The resin provides another positive effect by maintaining the layers of coiled wire in the stacked structure at their radial position relative to the center of the sleeve. Each layer transfers a portion of the load on the cable to the corresponding sleeve. In the cable according to WO'778, this load is transferred in the form of pressure to the underlying wire layer, i.e., the layer between the relevant layer and the load-bearing surface of the sleeve. This pressure can cause a decrease in the load-bearing capacity of the wire fibers, because high-performance fibers such as nylon fibers lose some of their load-bearing capacity if a lateral load is applied to the fibers. By applying the resin, at least a portion of the load is transferred via the resin rather than the underlying wire and compression, and thus wear is reduced or even eliminated entirely. In particular, the resin serves as the matrix. Another positive effect of the resin is the reduction of localized load transfer on the wire, because the surface of the wire is rough at a microscopic level, and the load is transferred to adjacent wires via the resin rather than primarily via protrusions on the rough wire surface.

[0024] It should be noted that US2013 / 0000087 (US'087) discloses a cable end connector for a cable constructed of multiple interwoven threads. The cable end connector includes an end portion for mounting or supporting the cable. The end portion is fastened to one end of the cable and is made of a castable, curable material—such as synthetic resin—connected to the threads in a form-fit manner solely by casting or molding, without the need for additional mechanical connecting elements. The threads are released from the original twisted assembly in the region of the end portion and are substantially uniformly distributed. The end portion is manufactured in a casting mold by injection molding of synthetic resin, and the threads are embedded under prestress and cast into the material of the end portion in a form-fit manner. Thus, the synthetic resin in US'087 forms the cable end assembly. If the synthetic resin breaks, or if the embedded threads detach from the resin, the entire end assembly will fail. In contrast, the end fitting of the present invention is made of a sleeve with an uninterrupted coil, wherein the resin or any other adhesive is used only to prevent mutual movement between the wire layers. If the adhesive fails, the end fitting of the present invention still functions as an end fitting similar to that in WO'778, and thus withstands long-term wear without immediate failure, like the cable end fitting in US'087.

[0025] In one embodiment, the wire layers within both sleeves are provided with a first adhesive. In embodiments with two or more sleeves, all sleeves are provided with a first adhesive.

[0026] In another embodiment, all the line layers in at least one of the sleeves are connected to each other by a cured first adhesive.

[0027] In embodiments, as disclosed in more detail in WO-2017 / 086778, prior to winding the wire, a stack of fibers of a different type than the fibers of the wire, particularly sheet-like pieces of such fibers, is disposed on the bearing surface of at least one sleeve.

[0028] In this embodiment, the synthetic fiber is a polyamide fiber, particularly nylon fiber, or polyester fiber. This gives the flexible cable increased elasticity.

[0029] In one embodiment, the cable includes at least a first sheet disposed in a stack of multiple layers of coiled wire, between two layers of a stack of one of a first sleeve and a second sleeve. Adding the first sheet between adjacent coil layers in the sleeve increases the stiffness of the stacked layers and thus minimizes relative movement between coil layers at the sleeve.

[0030] In one embodiment, the at least first sheet is one of a plurality of sheets, wherein each sheet is disposed in a stack of multiple layers of looped wire, between two layers of a stack of one of a first sleeve and a second sleeve. This structure with multiple sheets distributes the stress required to form the stack of wire layers across the multiple sheets, wherein the inserted sheets have sufficient stiffness.

[0031] In one embodiment, the two sleeves are stacked with at least one sheet-like element between the two layers of the line.

[0032] In this embodiment, at least the first sheet comprises a unidirectional fabric. This fabric provides maximum strength and stiffness in the direction of its fibers. Specifically, the fibers in the unidirectional fabric are oriented substantially parallel to the direction of the lines.

[0033] In this embodiment, at least the tensile stiffness of the first sheet is greater than the tensile stiffness of the wire. This increases the stopping effect of the sheet on the wire.

[0034] In an embodiment, at least the first sheet comprises sheet fibers, and the Young's modulus of the sheet fibers is higher than that of the thread fibers, specifically, at least twice the Young's modulus of the thread fibers. For example, the Young's modulus of the sheet fibers can be at least five times, or even at least ten times, the Young's modulus of the thread fibers.

[0035] In an embodiment, at least the first sheet comprises fibers selected from a list including carbon fibers, PBO (polybenzoxazole) fibers, and high-modulus aramid fibers.

[0036] In an embodiment, at least the first sheet comprises more than one fiber type, wherein at least one of these fiber types is selected from a list including carbon fiber, PBO fiber and high modulus aramid fiber.

[0037] In another aspect, the present invention relates to a method for producing a loop-wound flexible cable according to claim 14, and in particular to a method for producing a loop-wound flexible cable according to any one of claims 1 to 13 or the loop-wound flexible cable of the present invention as defined in the foregoing paragraphs.

[0038] By applying a first adhesive at least once at at least one location within the sleeve, at least two layers of the coil in the respective sleeve are interconnected. Therefore, the method according to the invention provides a loop-wound cable having the positive characteristics discussed above. The portion of the loop-wound cable extending between the first and second sleeves has substantially no cured first adhesive, thus maintaining the flexibility of the loop-wound flexible cable between the first and second sleeves. For example, at the portion of the cable extending between the sleeves, the first adhesive is not applied and / or cured. If desired, a second adhesive can be applied to the portion of the cable extending between the first and second sleeves, the second adhesive having a lower stiffness than the first adhesive, thus maintaining the flexibility of this portion.

[0039] In one embodiment, the step of applying the first adhesive results in connecting two or more layers of the coil. Due to the tension in the wire during winding, excess adhesive is squeezed from the initially adhesive-coated layer of the coil into other layers. Therefore, adding more first adhesive than is required for connecting two layers of the coil results in connecting more layers of the coil.

[0040] The dependent claims define the preferred method steps.

[0041] In an embodiment, the method includes the following steps: after at least one layer of the coil has been laid and before subsequent layers of the coil have been laid, placing at least a first sheet on one of the multiple layers of the coil in one of a first sleeve and a second sleeve.

[0042] In one embodiment, the method includes the step of placing an additional sheet on the other of a plurality of layers of a coil in one of a first sleeve and a second sleeve.

[0043] In one embodiment, during the fabrication of the loop-wound flexible cable, the following step is repeated at least a second time: a first adhesive is added to the layer of the coil in at least one of the sleeves.

[0044] In an embodiment, after n layers of coils are disposed in at least one of the sleeves, the following steps are repeated: a first adhesive is applied to the layers of coils in the at least one of the sleeves, wherein n is an integer, less than 15, particularly less than 10, particularly less than 5, and more particularly less than 2. This achieves precise addition of the desired amount of the first adhesive. In an embodiment, n is greater than 2. Preferably, n is selected from the range of 5 to 10.

[0045] The invention, its effects and advantages will be explained in more detail based on the illustrative accompanying drawings, in which: Figure 1 The end of the cable according to the invention is shown; Figure 2 It shows along Figure 4 The section decomposed from part II-II in the middle; Figure 3 It shows Figure 2 Enlarged details in the image; Figure 4 It shows Figure 1 A top view of the cable in the middle; Figure 5 It shows along Figure 4 The cross section cut by VV in the middle; and Figure 6 It shows along Figure 4 The section cut from VI-VI in the diagram.

[0046] Figures 1 to 6 A flexible cable according to the invention is shown, the flexible cable being generally indicated by reference numeral 1. The cable 1 has a first end fitting 3, a second end fitting 5, and a plurality of wires 6. The first end fitting 3 includes a first sleeve 2, and the second end fitting 5 includes a second sleeve 4. The first sleeve 2 and the second sleeve 4 are made of stainless steel, are disposed at opposite ends of the cable 1, and each has a center 7. In this embodiment, the plurality of wires 6 consists of ten (10) wires 6, all of which extend from the first sleeve to the second sleeve, turn around the second sleeve 4, extend from the second sleeve 4 to the first sleeve 2, and turn around the first sleeve 2. In this way, each of the plurality of wires 6 forms a semi-continuous loop around the first sleeve and the second sleeve. This loop is repeated multiple times, in this embodiment 950 times. Thus, each wire 6 is made into 950 loops, resulting in a total of 9500 loops of wire 6. Cables made in this manner are generally referred to as loop-wound cables. It should be noted that the attached diagram is for illustrative purposes only, and the actual (relative) dimensions of the cable differ from those shown in practice. In particular, the cable length is much greater than that shown in the diagram. Figure 4 The length shown is because the cable according to the invention can be hundreds of meters long, or even more than 1,000 meters.

[0047] In this embodiment, the thread 6 comprises nylon fiber, and the Young's modulus of the nylon fiber in this embodiment is 2.9 GPa.

[0048] Figure 2 The sleeve 2 is shown in cross-section, having a bearing surface 8. The sleeve 2 is held in a stack 9, which has multiple layers 10 of looped lines 6. This is in... Figure 3 It is shown in more detail in the middle. Figure 3 This is a significantly enlarged schematic diagram of the five (5) layers 10 of the circled line 6. Figure 2 The upper part, for clarity, shows stack 9 in an exploded diagram. In fact, as... Figure 2 As shown in the lower part, the entire stack 9 is held within the first sleeve 2. The second sleeve 4 holds the same layers of coil 6 in the same manner and is therefore not shown in detail.

[0049] Multiple layers 10 of wires 10 at one or both of the end fittings 3 and 5 of the cable 1 are connected to each other by a first adhesive, which in this embodiment is epoxy resin 12. In this embodiment, the epoxy resin 12 is disposed at each end fitting 3 and 5 and is cured to connect all layers 10 of the looped wires 6 in the stack of each sleeve 2 and 4 to each other. When the looped flexible cable is subjected to a load, the cured epoxy resin 12 maintains the tangential orientation of the respective layers 10 relative to each other.

[0050] In this embodiment, the cable 1 includes multiple sheet-like components 14, 16, 18, and 20 at the end fittings 3 and 5. The first sheet-like component 14 and the second sheet-like component 16 are disposed within a stack 9 of layers 10 of looped wire 6 at the first sleeve 2. The third sheet-like component 18 and the fourth sheet-like component 20 are disposed within a stack 9 of layers 10 of looped wire 6 at the second sleeve 4. Each of the multiple sheet-like components 14, 16, 18, and 20 is disposed between two layers of the respective stack 9. In this embodiment, the sheet-like components 14, 16, 18, and 20 are made of unidirectional carbon fiber fabric.

[0051] Epoxy resin 12 interconnects the layers 10 of the coiled wires 6 with the sheet elements 14, 16, 18, 20. The sheet elements increase the stiffness of the stack 9 of each sleeve 2, 4, thereby reducing the movement of the stack as a whole and the relative movement of the layers 10 of the coiled wires 9.

[0052] The cable cover 28 extends around the cable 1 from the first sleeve 2 to the second sleeve 4, and bundles all the coils 6 extending between the first sleeve 2 and the second sleeve 4 into a compact bundle 30 at the middle section 32 of the cable 1. In this embodiment, the middle section 32 is shown as relatively short compared to the total length of the cable 1. In most embodiments, the middle section is the longest section of the cable. In this embodiment, the cable cover 28 also covers the coils 6 at the end fittings 3, 5. The cable cover 28 creates converging sections 33, 34 of the looped wires 6 that extend from the respective sleeves 2, 4 to the middle section 32.

[0053] Figure 5 As shown, the cable 1 in the middle section 32—that is, the cable 1 between the end fittings 3 and 5—is formed by looped wires 6, wherein there is no epoxy resin 12 or any other adhesive between the wires 6, so that the cable maintains its flexibility.

[0054] Figure 6 This is a schematic diagram of a longitudinal section passing through end fitting 5. In this embodiment, the longitudinal section passing through end fitting 3 is similar and therefore not shown in detail. Figure 6 The inner contour 40 and outer contour 42 of the converging section 34 of the bundled coil 6 are shown, while the coil 6 engages with and oriented around the sleeve 4. Since the coil 6 is bundled in the intermediate section 32, it is divided into two halves and diverges towards the sleeve 4. In this embodiment, the coil 6 engages with the bearing surface 8 of the sleeve 4 corresponding to an angle α, which is approximately 220°. Sheets 18 and 20 extend around the sleeve 4 at least by the same angle α and across the entire width of the bearing surface 8. In this embodiment, sheets 18 and 20 extend from the sleeves 2 and 4 through the converging sections 33 and 34 toward the intermediate section 32 to increase the surface area for bonding sheets 18 and 20 to the layer 10 of the coiled wire 6 using epoxy resin 12. Sheets 18 and 20 do not extend into the intermediate section 32, thus not affecting the elasticity of the intermediate section 32.

[0055] The area supported by the bearing surface 8 and the support line 6 is called the support area 44. For example... Figure 6 The dotted line indicates that the support region 44 covers an angle α. Typically, the first adhesive is applied to a segment 46 of the support region 44. In a preferred embodiment, the segment 46 is substantially the entire support region 44. This allows the wires 6 to interconnect throughout the support region 44, thereby preventing movement of the wires 6 relative to each other and thus preventing fiber abrasion, which can lead to premature failure of the corresponding cable 1.

[0056] In an alternative embodiment, the first adhesive is present in other parts of the respective end assembly, particularly within the entire end assembly.

[0057] In an alternative embodiment, the first adhesive covers less than half of the support region 44, such as 1 / 3 or 1 / 4 of the support region 44 as shown in FIG. 14. The segment 46 with the first adhesive is centered on the longitudinal axis 48 of the cable 1.

[0058] The cured first adhesive bonds at least two of the plurality of layers 10 of the wire 6. In a preferred embodiment, substantially all layers of the wire are bonded by the cured first adhesive. Bonding substantially all layers of the coil results in a significantly longer service life compared to bonding only two layers. In the context of this specification, substantially all layers of the coil are interpreted as at least 80% of the plurality of layers, particularly at least 90% of the plurality of layers, and more particularly at least 95% of the plurality of layers.

[0059] In the embodiment, at the portion of the unsupported looping line 6 on the bearing surface 8, that is, at the unsupported area spanning the remaining (360°-α) degrees, for example, across... Figure 6 In the example, the remaining 140° unsupported area was not coated with the first adhesive.

[0060] The flexible cable according to the invention has been tested and has not broken after more than nine million load cycles. Multiple tests have shown that, measured by the number of load cycles, the invention increases service life by 30 to 50 times.

[0061] An embodiment of the method for producing a loop-wound flexible cable—such as one of the embodiments disclosed above—according to the present invention includes the following steps: The first and second sleeves are positioned relative to each other at a predetermined distance, corresponding to the required cable length. Ten nylon threads are provided. Wind the ten threads from the first sleeve to the second sleeve, around the second sleeve half a turn, back to the first sleeve, and around the first sleeve half a turn again. The first adhesive is applied to the coil layer inside the sleeve. Repeat the process of winding ten wires around the first and second sleeves until a first predetermined number of layers of coils are formed in both the first and second sleeves. The first unidirectional carbon fiber sheet is placed on one of the layers of the coil in the first sleeve. The second unidirectional carbon fiber sheet is placed on one of the layers of the coil in the second sleeve. Apply more of the first adhesive to the coil layer inside the bushing. Repeat the step of winding ten wires around the first and second sleeves on the first and second sheet pieces until a second predetermined number of layers of coils are formed in both the first and second sleeves. Place another sheet-like component on one of the coil layers in the first sleeve. Place a second, additional sheet-like component on one of the coil layers in the second sleeve. Apply more of the first adhesive to the coil layer inside the bushing. Repeat the step of winding ten wires around the first and second sleeves until a third predetermined number of coil layers are formed in both the first and second sleeves, wherein the first, second, and third predetermined number of coil layers together correspond to the required cable thickness, and The first adhesive is cured so that when the looped flexible cable is subjected to a load, the layers of the coil maintain a tangential orientation relative to each other.

[0062] In this embodiment, the first adhesive is not applied to every layer, but rather a sufficient amount is applied each time to diffuse through adjacent layers and sheets, such that in the final product, the first adhesive is present between all layers and between layers and sheets before the first adhesive cures.

[0063] In this embodiment, the first adhesive is epoxy resin.

[0064] In this embodiment, the epoxy resin is a thermosetting polymer that is cured by heating the first sleeve and the second sleeve.

[0065] In this embodiment, the first sleeve and the second sleeve are made of stainless steel.

[0066] In an alternative embodiment, after all layers of the coil have been applied to the bushings, i.e., after a complete stack of layers has been formed in each bushing, a first adhesive is applied. The first adhesive penetrates between the layers of the coil, also penetrates through the sheet, and diffuses throughout the entire stack.

[0067] The same applicant described equipment suitable for methods of making looped winding cables in WO-2017 / 099589 and WO-2017 / 086778.

[0068] Several variations are possible within the scope of the appended claims. One or more features of the above preferred embodiments may be replaced by any other feature within the scope of the appended claims, such as those described in other embodiments and in the following paragraphs. The disclosed method-related product features are preferred features of the flexible cable, and the disclosed product-related method features are preferred features of the method for producing the flexible cable.

[0069] The cable according to the invention can be made of ten or fewer wires, such as one wire, two wires, or at least five wires. In particular, the cable is made of at least 12 wires or 24 wires. The total number of coils, i.e., the number of coils in each layer and the number of layers, depends on the required cable strength and the strength of the individual wires, as well as the required safety margin. The number of layers depends on the required number of coils and the available width in the sheath, which produces the maximum number of coils in the width direction. In particular, each wire is made with at least one thousand turns, more particularly, more than five thousand turns.

[0070] In this embodiment, the first adhesive is applied to the yarn layer in only one of the sleeves. In particular, in this embodiment, one sleeve differs from the other, such that the effect of the first adhesive is less, for example, if the load on the fibers is less due to the larger radius and / or wider width of the respective sleeve.

[0071] In one embodiment, a second adhesive is applied to the annularly wound flexible cable between the sleeves. The stiffness of the second adhesive is lower than that of the first adhesive, thus maintaining the flexibility of the annularly wound flexible cable between the sleeves. An annularly wound cable is considered flexible if it can be wound up, for example, for transport. This flexibility also exists if the different layers of looped wire in the annularly wound cable between the sleeves can shift relative to each other in its longitudinal direction.

[0072] In one embodiment, a first adhesive is applied to the annular wound cable extending between the sleeves but is not cured, and / or, the first adhesive is applied to and cured only on a small portion of the annular wound cable in the length and / or width directions, such that the annular wound cable as a whole maintains flexibility.

[0073] In one embodiment, the flexible cable includes two or more sleeves. In this embodiment, at least two sleeves are present at one end of the flexible cable. Two sleeves in an end fitting form a concave end fitting, allowing connection to another flexible cable to be established by placing a convex end fitting between the sleeves of the concave end fitting.

[0074] In the embodiments, another type of resin, such as polyester resin, vinyl ester resin, or polyamide, may be used. In particular, the resin is a thermosetting polymer.

[0075] In one embodiment, the first adhesive is applied only to one part of the sleeve.

[0076] In one embodiment, the first adhesive is applied only to the sleeve of one or both of the end fittings, and not to the converging section of the looped wires in the end fitting.

[0077] In this embodiment, the adhesive was not applied to the portion of the bearing surface that did not support the looped line, i.e., it was not applied to the unsupported area spanning the remaining (360°-α) degrees.

[0078] In an embodiment, a first adhesive is applied during the winding of one or more wires, i.e., the first adhesive is applied on the top of each layer of the coil, or on the top of each nth layer of the coil, where n is an integer equal to or greater than one (1) and less than the total number of coils in the stack.

[0079] In one embodiment, the first adhesive is cured by adding a curing agent—such as a polyamine curing agent for resins. In another embodiment, the first adhesive is cured by means of radiation—such as IR radiation, UV radiation, or microwave radiation. In yet another embodiment, the first adhesive is cured by evaporating the solvent of the first adhesive.

[0080] Unidirectional fabrics have parallel fibers that provide the required strength and / or stiffness. These parallel fibers need to be stabilized, for example, by applying warp threads or an adhesive, such as a polyester adhesive. The weight of these warp threads or adhesives constitutes a small portion of the fabric, for example, less than 5% of the total fabric weight, and particularly less than 1% of the total fabric weight. Unidirectional fabrics with applied warp threads could theoretically be considered woven fabrics. However, because the warp threads constitute a small portion of the overall fabric and have no structural function other than stabilizing the fibers, such fabrics are generally considered nonwoven. Unidirectional fabrics using adhesives are also referred to in practice as true nonwoven unidirectional fabrics.

[0081] While unidirectional fabric is preferably used as a sheet, in other embodiments, the sheet is a textile sheet, a woven sheet, or a knitted sheet. In alternative embodiments, the sheet is made of PBO fibers or high-modulus aramid fibers.

[0082] The present invention achieves advantageous effects by connecting at least two layers of the coil. However, connecting substantially all layers of the coil results in an even better increase in service life. In the context of this specification, substantially all layers of the coil are interpreted as at least 80% of the plurality of layers, particularly at least 90% of the plurality of layers, and more particularly at least 95% of the plurality of layers.

[0083] Typically, the looped lines join the bearing surface of the sleeve in the circumferential direction, corresponding to angle α, where α is greater than 180° and less than 360° of the perimeter of the bearing surface of the sleeve. In an embodiment, α is greater than 200° of the bearing surface of the sleeve, particularly greater than 220°, and even more particularly greater than 240°. In an embodiment, α is less than 340° of the bearing surface of the sleeve, particularly less than 320°, and even more particularly less than 300°.

[0084] In each end fitting, the plate extends at least at the same angle α as the angle corresponding to the bearing surface of the coiled wire engagement. Specifically, the plate extends from the sleeve into the converging section. Specifically, the plate extends at least 20% and at most 100% of the length of the associated converging section. Specifically, the plate extends at least 50% of the length of the associated converging section, more particularly at least 75%. Specifically, the plate extends a maximum of 90% and particularly 80% of the length of the associated converging section.

[0085] In one embodiment, one or both of the bushings do not have a sheet-like element. In another embodiment, one or both of the bushings have a sheet-like element. In yet another embodiment, the sheet-like element is disposed between every nth and (n+1th)th layers of the coil, where n is an integer, at least 1, and less than the number of layers. In one embodiment, n equals ten. In another embodiment, n equals six. In yet another embodiment, n equals three.

[0086] In this embodiment, the sleeve is made of a plastic material instead of a metal, or of a metal other than stainless steel, including but not limited to various steel alloys, aluminum alloys, magnesium alloys, and titanium.

[0087] It should be noted that in the above instructions, terms such as “fiber,” “mold,” and “center” are spelled in British English. These terms can be replaced with the corresponding American English spellings “fiber,” “mold,” and “center” without altering the content of this instruction manual.

Claims

1. A flexible cable (1) made by annularly winding at least one wire around two sleeves, the flexible cable (1) comprising a first sleeve (2) and a second sleeve (4) and at least one wire (6), wherein, The first sleeve (2) and the second sleeve (4) are located at opposite ends of the cable (1). The at least one wire (6) extends from the first sleeve (2) to the second sleeve (4), turns around the second sleeve (4), extends from the second sleeve (4) to the first sleeve (2), and turns around the first sleeve (2), such that the wire (6) forms a loop around the first sleeve (2) and the second sleeve (4), and each sleeve (2, 4) maintains a stack (9) of multiple layers (10) of the looped wire (6), characterized in that, The thread (6) comprises synthetic or natural fibers with a Young's modulus of 0.1 GPa to 54 GPa, wherein the Young's modulus is determined according to ASTM D2256 standard, and A first adhesive (12) is applied at at least one of the first sleeve and the second sleeve, and the first adhesive (12) is cured to connect at least two layers of the plurality of looped wires (10) in the stack (9) of the respective first sleeve (2) or second sleeve (4) to maintain the tangential orientation of the respective wire layers (10) relative to each other when the looped flexible cable is under load, while the wires are substantially uncured between the first sleeve and the second sleeve, so that the cable remains flexible between the first sleeve and the second sleeve.

2. The flexible cable according to claim 1, wherein, The synthetic fiber is a polyamide fiber, particularly a nylon fiber, or a polyester fiber.

3. The flexible cable according to claim 1 or 2, the flexible cable comprising at least a first sheet (14) disposed in the stack (9) of a plurality of layers (10) of the looped wire (6), between two layers of the stack of the first sleeve and the second sleeve.

4. The flexible cable according to claim 3, wherein, The at least first sheet is one of a plurality of sheets (14, 16, 18, 20), wherein each sheet is disposed in the stack (9) of a plurality of layers (10) of the looped line (6), between two layers of the stack of the first sleeve and the second sleeve.

5. The flexible cable according to any one or more of claims 3-4, wherein, The at least first sheet-like component comprises unidirectional fabric.

6. The flexible cable according to any one or more of claims 3-5, wherein, The tensile stiffness of at least the first sheet is greater than the tensile stiffness of the wire.

7. The flexible cable according to any one or more of claims 3-6, wherein, The at least first sheet comprises sheet fibers, and the Young's modulus of the sheet fibers is higher than that of the Young's modulus of the fibers of the thread, in particular, at least twice that of the Young's modulus of the fibers of the thread.

8. The flexible cable according to any one or more of claims 3-6, wherein, The at least first sheet-like member comprises fibers selected from a list including carbon fibers, PBO fibers, and high-modulus aramid fibers.

9. The flexible cable according to any one or more of the preceding claims, wherein, The stack (9) of the plurality of looped lines (6) of each sleeve engages with the respective sleeve along a portion (44) of the periphery of the respective sleeve, wherein the cured first adhesive (12) disposed at at least one of the first sleeve (2) and the second sleeve (4) extends at least on a section (46) of the circumferential portion (44) of the respective first sleeve (2) or second sleeve (4).

10. The flexible cable according to claim 9, wherein, The cured first adhesive (12) extends over the entire circumferential portion (44).

11. The flexible cable according to claim 9, wherein, The cured first adhesive (12) extends only on the section (46) of the circumferential portion (44), and in particular, the section (46) is centered on the longitudinal axis (48) of the cable (1).

12. The flexible cable according to any one or more of the preceding claims, wherein, The first adhesive comprises a resin (12), particularly an epoxy resin.

13. The flexible cable according to any one or more of the preceding claims, wherein, A second adhesive is applied to the cable between the first sleeve and the second sleeve. The second adhesive has a lower Young's modulus than the cured first adhesive, so that the cable remains flexible between the first sleeve and the second sleeve.

14. A method for producing a loop-wound flexible cable, particularly a method for producing a loop-wound flexible cable according to any one or more of the preceding claims, the method comprising the steps of: The first and second sleeves are positioned relative to each other at a predetermined distance, which corresponds to the required cable length. Provide at least one thread comprising synthetic or natural fibers with a Young's modulus of 0.1 GPa to 54 GPa, wherein the Young's modulus is determined according to ASTM D2256 standard. The at least one wire is wound from the first sleeve to the second sleeve, around the second sleeve half a turn, returned to the first sleeve, and around the first sleeve half a turn again. Repeat the previous step until a predetermined number of coil layers are formed in both the first and second sleeves, the predetermined number of coil layers corresponding to the desired cable thickness. The steps of applying a first adhesive to at least one of the coil layers in the sleeve, and The step of curing the first adhesive at at least one of the sleeves connects at least two of the plurality of layers of the coil to each other to maintain the tangential orientation of the respective layers relative to each other when the annularly wound flexible cable is under load. At the same time, the first adhesive is substantially uncured from the line between the first sleeve and the second sleeve, so that the cable remains flexible between the first sleeve and the second sleeve.

15. The method according to claim 14, wherein the method comprises the following steps: After at least one layer of the coil has been laid and before subsequent layers of the coil have been laid, at least a first sheet is placed on one of the plurality of layers of the coil in one of the first sleeve and the second sleeve.

16. The method according to claim 15, wherein the method comprises the following steps: An additional sheet is placed on the other of the plurality of layers of the coil in one of the first and second sleeves.

17. The method according to any one or more of claims 14-16, wherein, After n layers of coils are disposed in at least one of the sleeves, the following steps are repeated: the first adhesive is applied to the layers of coils in the at least one of the sleeves, and wherein n is an integer less than 10, particularly less than 5, and more particularly less than 2.

18. The method according to any one or more of claims 14-17, wherein, The first adhesive is applied such that it substantially penetrates all layers of the coil and optional sheet elements and additional sheet elements, and wherein the step of curing the first adhesive is performed such that all layers of the coil and optional sheet elements and additional sheet elements are connected, so that substantially all layers of the coil maintain a tangential orientation relative to each other when the annularly wound flexible cable is subjected to a load.

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