Aramid umbilical cable armoring structure and production method thereof

Abstract

The invention discloses an aramid umbilical cable armoring structure and a production method thereof, the aramid umbilical cable armoring structure comprises N aramid armoring layers which are sequentially arranged on the outer side of a cable core from inside to outside, and further comprises paraffin and N non-woven fabric layers, the non-woven fabric layers are in one-to-one correspondence with the aramid armoring layers, and the N non-woven fabric layers are in one-to-one correspondence with the aramid armoring layers. The non-woven fabric layers are respectively wrapped on the outer sides of the corresponding aramid fiber armor layers, the paraffin is coated on each aramid fiber armor layer and infiltrates the corresponding aramid fiber armor layer and the non-woven fabric layer, and the aramid fiber armor layers are wrapped through the non-woven fabric layers, so that the aramid fiber armor layers can be bundled, the consistency of aramid fibers on the same layer is enhanced, the output efficiency is improved, and the service life of the aramid fiber armor layers is prolonged. The aramid fibers between different layers can be isolated, and the paraffin is used for lubrication, so that the friction between the aramid fibers is reduced, and the breaking force value and the bending fatigue performance are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of aramid umbilical cables, and particularly to an aramid umbilical cable armor structure and a production method thereof. Background Art

[0002] As a key component of the underwater control system, the umbilical cable system is the "nerve and lifeline" connecting the offshore platform facilities and the underwater production system. With the continuous advancement of deep-sea exploration, umbilical cables are also developing towards greater water depths, ultra-deep waters, and even full ocean depths. Especially with the development of seabed development and mining, higher requirements for stronger, lighter, and higher reliability are put forward for umbilical cables.

[0003] Due to its large self-weight, when the water depth exceeds 5000m, the increase in the strength of the steel wire is contradictory to the self-weight that increases with the increase in the diving depth, and balance cannot be achieved. Therefore, in order to reduce the self-weight, the steel wire armor of the heavy-duty deep-sea umbilical cable turns to high-strength non-metallic fiber armor. Among them, high-strength non-metallic fiber armored cables such as aramid and LCP are gradually applied in the field of umbilical cables due to their light weight and high strength.

[0004] There are also problems with non-metallic fiber armor. When the amount of non-metallic fiber exceeds several hundred thousand dtex, a large amount of fiber armor is required, and there are significant differences in the output consistency of large-denier fibers, resulting in a reduction in the output efficiency.

[0005] Common methods in the industry to increase the overall consistency of aramid include impregnated aramid, aramid rods, etc. Glue is used in the production process to increase the adhesion between the sheath and the aramid. These methods have a certain effect in the direction of improving the breaking force. However, the adoption of these methods increases the overall stiffness of the aramid reinforcement layer, resulting in a reduction in the relative slip inside the aramid during stress and bending, an increase in the risk of stress concentration, resulting in local bending during use, a decrease in the overall strength, and insufficient bending fatigue resistance.

[0006] During the use of aramid umbilical cables, the friction between aramids also reduces the use strength and needs to be improved. Summary of the Invention

[0007] The main technical problem to be solved by the present invention is to provide an aramid umbilical cable armor structure and a production method thereof, which can improve the output consistency between fibers, take into account the bending fatigue performance, and reduce the friction between aramids.

[0008] To solve the above technical problems, a technical solution adopted by the present invention is: to provide an aramid umbilical cable armor structure, including: N layers of aramid armor layers sequentially arranged outside the cable core from inside to outside, and further including paraffin and N layers of non-woven fabric layers. The non-woven fabric layers correspond to the aramid armor layers one by one, and the non-woven fabric layers are respectively wound around the outside of the corresponding aramid armor layers. The paraffin is coated on each layer of aramid armor layer and infiltrates the corresponding aramid armor layer and non-woven fabric layer.

[0009] In a preferred embodiment of the present invention, the cable core includes an inner sheath and an optical fiber unit and a wire located in the inner sheath.

[0010] In a preferred embodiment of the present invention, the aramid armor layer is armored outside the inner sheath.

[0011] In a preferred embodiment of the present invention, the aramid umbilical cable further includes an outer sheath, and the outer sheath is arranged outside the Nth non-woven fabric layer.

[0012] In a preferred embodiment of the present invention, N is not less than 2.

[0013] To solve the above technical problems, another technical solution adopted by the present invention is: to provide a production method of an aramid umbilical cable armor structure, including the following steps: A. Pay off the cable core: Pay off the cable core and aramid, adjust the pay-off speed and pay-off tension, and set the pay-off tension of the twisted aramid (about 60000 dtex), so that the aramid can be tightened. The pay-off tension range is 8 - 10 kg, which can keep the synchronous stretching of different strands of aramid after armoring. Through the armoring equipment, the aramid is armored outside the cable core to form an aramid armor layer; B. Coating of paraffin: Use a hot melt adhesive machine to melt the paraffin, pump out the liquid paraffin by a pressure pump, and transfer it to a paraffin mold through a heat-insulating pipeline, and coat the liquid paraffin on the surface of the aramid armor layer passing through the paraffin mold; C. Winding of non-woven fabric: Through a wrapping equipment, wind the non-woven fabric on the surface of the aramid armor layer after coating the paraffin to tie the aramid armor layer tightly to form a non-woven fabric layer. Add a heating device to heat the non-woven fabric layer passing through the heating device, so that the paraffin melts again, better infiltrates the aramid and non-woven fabric, and enhances the interlayer lubrication between the non-woven fabric layer and the aramid armor layer; D. Armoring of the Nth aramid armor layer: Through the above steps, outside the (N - 1)th non-woven fabric layer, armor the Nth aramid armor layer, coat the paraffin, and then wind and heat the Nth non-woven fabric layer to form an armor structure with N layers of aramid armor layers; By adjusting the tension of the armor, the outer aramid armor layer is tightened, and the non-woven fabric layer is used for winding and the lubrication of paraffin wax is utilized to enhance the consistency of the aramid in the same layer. At the same time, the aramid between different layers maintains good lubrication to reduce wear; E. Pay-off: Traction of the cable core is carried out, and the armored cable core is evenly arranged on the spools of the pay-off stand; First, a wheel-type tractor provides the traction force, and then a crawler-type tractor is used for traction to isolate the pay-off stand and the wheel-type tractor.

[0014] In a preferred embodiment of the present invention, the heating device includes a heating sleeve.

[0015] The beneficial effects of the present invention are as follows: An aramid umbilical cable armor structure and its production method pointed out by the present invention, through the winding of the aramid armor layer with a non-woven fabric layer, can not only achieve the bundling of the aramid armor layer, enhance the consistency of the aramid in the same layer, and improve the output efficiency, but also isolate the aramid between different layers. Coupled with the lubrication of paraffin wax, the friction between the aramids is reduced, the breaking force value and the bending fatigue performance are enhanced, and it is applicable to the production of aramid umbilical cables with large water depths and large loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings, where: Figure 1 is a schematic structural diagram of an aramid umbilical cable armor structure of the present invention; Figure 2 is a schematic diagram of the production line adopted by the production method of an aramid umbilical cable armor structure of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0018] Analyze the factors affecting the strength and bending performance of the aramid armored cable: Strength analysis

[0019] The strength formula of the aramid armored cable is:

[0020] i is the number of armor layers; M i is the armor wire linear density of the i-th layer; E is the elastic modulus of the armor fiber; α i is the fiber armor angle of the i-th layer; ρ is the fiber density; ε is the in-line tensile strain; μ is the output coefficient; For aramid armored cables, since the properties of the materials are fixed, E, ρ, and ε are fixed, and α i For umbilical cables, usually the angle is also within a fixed range, so the only factors that can improve the strength are i, M i and μ.

[0021] Increasing i and M i will increase the overall amount of aramid used, increase the outer diameter, increase the cost of the production finished product, require a larger winch and more space during use, greatly increase the cost of the entire system. At the same time, more aramid will reduce the output efficiency, which is often not feasible. Therefore, the industry has focused on the output coefficient μ.

[0022] The output coefficient of large-count aramid is relatively low, usually below 70%, and even below 50%.

[0023] The reasons are as follows: 01. Aramid armor usually uses aramid yarns of several hundred thousand dtex. When used in large quantities, the fiber filaments are equivalent to re-parallelizing a large number, and the lengths between different filaments inside are inconsistent, resulting in a low output coefficient; 02. Different aramid yarns have changes in tightness and looseness after being stressed, and the elongations are inconsistent, resulting in an increase in the frictional force between the wires and the formation of internal stress concentration; 03. The tension is unstable during the armor process, which will also cause the aramid yarns to loosen, but current equipment can usually overcome this.

[0024] Regarding the above problems of large-count aramid armor, the commonly used methods in the industry at present are: 01. Adopt the method of increasing the rigidity of aramid, similar to the form of steel wires. The output coefficient of steel wire armor can reach more than 90%, such as the form of aramid rods and impregnated aramid forms; 02. Improve the bonding force between different aramid armor layers and between aramid and the sheath, and strive for the cable structure and aramid to be synchronized under tension. Usually, the method of glue coating is adopted.

[0025] The above methods can indeed achieve an increase in the output coefficient and an increase in the breaking force, but the increase in rigidity brings a decrease in the bending performance. Analysis of the influence of bending fatigue

[0026] 01. Influence of the bending outer diameter: When bent, there is a height difference between different parts of the cable and the central axis of the cable, causing the outer side of the cable to be stretched and the inner side to be compressed. When not under force, the relative slippage inside the cable releases stress and reduces deformation. However, when under force, the slippage is affected by frictional resistance, and the stress cannot be released in time, resulting in structural elongation. At the same time, the frictional loss between fibers increases. This repeated slippage over a long time causes structural fatigue and ultimately leads to structural failure.

[0027] 02. Influence of tensile force: Tensile force can cause the cable to elongate. At the same time, the load-bearing aramid compresses the cable core, causing internal pressure. When the cable is bent, it generates a squeezing force on the cable by the pulley. This squeezing makes it more difficult for the slippage caused by bending to occur. The structural deformation caused by bending is not released through slippage. Under the combined action of deformation and tensile deformation, the deformation amount of the internal fibers of the aramid armor layer increases, and the risk of local damage caused by stress concentration increases.

[0028] 03. Cable structure: From a structural perspective, the part close to the center of the cable is less affected by bending, while the outer side is more affected. From a material perspective, the armor material with a rigid structure is more likely to slip and not easily bent and deformed. However, once bent, it will cause irreversible damage and reduce the overall performance. While a flexible and well-lubricated structure can release stress through slippage and thus has better bending performance.

[0029] Through the above analysis, we found a contradiction in improving strength and bending performance.

[0030] The method of increasing the rigidity of aramid enhances the output force coefficient, but increases the risk of aramid structure bending. The method of increasing the bonding force between aramid armor layers limits the relative slippage between layers, and at the same time makes the stress unable to be evenly dispersed, increasing the risk of stress concentration.

[0031] Through the above analysis, the advantages and disadvantages of existing methods are summarized, and a design scheme that takes into account both the strength and bending performance of the aramid armor umbilical cable is proposed.

[0032] Please refer to Figure 1 , the embodiments of the present invention include: An aramid umbilical cable armor structure, including: N layers of aramid armor layers 100, paraffin, and N layers of non-woven fabric layers 200 arranged in sequence from the inside to the outside on the outer side of the cable core. In this embodiment, the cable core includes an inner sheath 300 and an optical fiber unit and a wire located in the inner sheath 300. The aramid armor layer 100 is armored on the outer side of the inner sheath 300.

[0033] The non-woven fabric layer 200 corresponds to the aramid armor layer 100 one by one, and the non-woven fabric layer 200 is respectively wrapped around the outside of the corresponding aramid armor layer 100. Paraffin is coated on each aramid armor layer 100 and infiltrates the corresponding aramid armor layer 100 and non-woven fabric layer 200. The bundling of the aramid armor layer 100 is realized through the non-woven fabric layer 200, which enhances the consistency of the aramid in the same-layer aramid armor layer 100, improves the output efficiency, and can also isolate the aramid between different aramid armor layers 100. Coupled with the lubrication of paraffin, the friction between the aramids is reduced, and the breaking force value and bending fatigue performance are enhanced.

[0034] As Figure 1 shown, the aramid umbilical cable further includes an outer sheath 400. The outer sheath 400 is arranged on the outside of the Nth non-woven fabric layer, where N is not less than 2. In this embodiment, N is taken as 3. A structure of 3 aramid armor layers 100 and 3 non-woven fabric layers 200 is adopted, and the third non-woven fabric layer is protected by the outer sheath 400. With the lubrication of paraffin, the adverse effects on the non-woven fabric layer and the aramid armor layer during the bending of the outer sheath 400 are reduced.

[0035] Please refer to Figure 2 , a production method of an aramid umbilical cable armor structure, which adopts the Figure 2 shown production line. The production line includes a cable core pay-off reel 1, a first pay-off and take-up balancer 2, multiple armor wrapping and winding combination devices 16, a wheel-type traction wheel 10, a caterpillar traction machine 11, a second pay-off and take-up balancer 12, and a take-up reel 13 arranged in sequence according to the process order. The armor wrapping and winding combination devices 16 respectively include a first guide wheel 3, an aramid pay-off reel 4, an armor device 5, a straightening wheel group 15, a paraffin mold 6, a second guide wheel 7, a wrapping machine 8, and a heating device 9 arranged in sequence according to the process order. A hot melt adhesive machine 14 is arranged on one side of the paraffin mold 6 to provide liquid paraffin for the paraffin mold 6. The method includes the following steps: A. Pay off the cable core: The cable core is payed off through the cable core pay-off reel 1, and the pay-off speed and pay-off tension are adjusted through the first pay-off and take-up balancer 2; The aramid is payed off through the aramid pay-off reel 4. The pay-off tension of the twisted aramid (about 60000 dtex) is set, and the aramid can be tightened. The aramid pay-off tension range is 8 - 10 kg, which can keep the synchronous stretching of different strands of aramid after armor. The cable core is sent into the armor device by using the first guide wheel 3, and the aramid is armored on the outside of the cable core through the armor device to form the aramid armor layer 100. The straightening wheel group 15 is used to straighten the cable core after the aramid armor layer 100 is armored; In this embodiment, the aramid adopts a multi-strand twisting method. Twisting can improve the overall strength of the aramid yarn, and the appearance is more regular, reducing burrs; B. Coating with paraffin wax: Using a hot melt adhesive machine 14, melt the paraffin wax, pump out the liquid paraffin by means of a pressure pump, transfer it through a heat-insulating pipeline to a paraffin wax mold 6, and coat the liquid paraffin on the surface of the aramid armor layer 100 passing through the paraffin wax mold 6. The liquid paraffin is pre-cooled and solidified on the aramid armor layer 100; C. Winding non-woven fabric: Feed the cable core into a wrapping device 8 by means of a second guide wheel 7. Through the wrapping device 8, wind non-woven fabric on the surface of the aramid armor layer 100 after paraffin wax coating to tie up the aramid armor layer 100 and form a non-woven fabric layer 200. Through a heating device 9, heat the non-woven fabric layer 200 passing through the heating device 9. In this embodiment, the heating device includes a heating sleeve, and the non-woven fabric layer 200 passes through the heating sleeve for 360° heating, so that the paraffin wax on the aramid armor layer 100 melts again, better infiltrates the aramid and the non-woven fabric, and enhances the interlayer lubrication between the non-woven fabric layer 200 and the aramid armor layer 100; The non-woven fabric can be used as a bundling material to bundle each layer of the aramid armor layer 100 into a round shape, enhancing the structural stability. The gaps between the fibers in the non-woven fabric can also soak in paraffin wax. Paraffin wax is used as a lubricant. When paraffin wax is coated on the surface of an object, a lubricating film is formed on the surface of the object, reducing the friction force on the surface of the object. Moreover, paraffin wax is a solid structure after cooling and has stable performance; In this embodiment, the non-woven fabric uses nylon fiber non-woven fabric, the thickness of the non-woven fabric is 0.2 - 0.4 mm, and the wrapping overlap rate is 25% - 35%, ensuring 100% coverage of the aramid armor layer 100. The nylon material has excellent mechanical properties, is oil-resistant, heat-resistant, wear-resistant, and has a low friction coefficient. The gaps between the fibers are conducive to the infiltration of paraffin wax, thereby further reducing friction; D. Armor of the Nth layer of aramid armor layer: Through the above steps, on the outer side of the (N - 1)th layer of non-woven fabric layer, armor the Nth layer of aramid armor layer. After coating with paraffin wax, wind and heat the Nth layer of non-woven fabric layer to form an armored structure with N layers of aramid armor layer; By adjusting the tension of the armor, tighten the outer aramid armor layer 100, and use the non-woven fabric layer 200 for wrapping and the lubrication of paraffin wax to enhance the consistency of the aramid in the same layer of the aramid armor layer 100. At the same time, the aramid between different aramid armor layers 100 maintains good lubrication, reducing wear problems; Using large-count twisted aramid as the armored reinforcement material, winding non-woven fabric between layers, and adhering paraffin wax on the surface can enhance the output consistency and strength between the aramid in the same layer, reduce the interlayer friction between different layers, make the structure round, and is conducive to the uniform extrusion of the take-up and pay-off and the outer sheath, so as to achieve the purpose of improving the strength and bending performance of the umbilical cable; E. Wire winding: Traction of the cable core is carried out, and the armored cable core is evenly arranged on the spool of the wire winding frame 13. Specifically, first, the traction force is provided by the wheeled tractor 10, then the tracked tractor 11 is used for traction to isolate the wire winding frame 13 and the wheeled tractor 10. Finally, after passing through the second wire winding and unwinding balancer 12, the wire is wound through the wire winding frame 13.

[0036] In summary, a kevlar umbilical cable armor structure and its production method proposed by the present invention can effectively improve the overall output coefficient of the armored kevlar of the kevlar umbilical cable, increase the breaking force, reduce the friction damage between kevlar layers during bending, and enhance the bending performance.

[0037] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. An aramid umbilical cable armor structure, armored outside the cable core of the aramid umbilical cable, comprising: N layers of aramid armor layers are successively arranged outside the cable core from the inside to the outside, and it is characterized in that it further includes paraffin and N layers of non-woven fabric layers. The non-woven fabric layers correspond to the aramid armor layers one by one, and the non-woven fabric layers are respectively wound around the outside of the corresponding aramid armor layers. The paraffin is coated on each layer of aramid armor layer and infiltrates the corresponding aramid armor layer and non-woven fabric layer.

2. The aramid umbilical cable armor structure according to claim 1, wherein The cable core includes an inner sheath and an optical fiber unit and a wire located in the inner sheath.

3. The aramid umbilical cable armor structure according to claim 2, characterized in that, The aramid armor layer is armored outside the inner sheath.

4. The aramid umbilical cable armor structure according to claim 1, wherein, The aramid umbilical cable further includes an outer sheath, and the outer sheath is arranged outside the Nth non-woven fabric layer.

5. The aramid umbilical cable armor structure according to claim 1, characterized in that, The N is not less than 2.

6. A production method of an aramid umbilical cable armor structure, characterized in that, It includes the following steps: A. Pay off the cable core: Pay off the cable core and the aramid, and armor the aramid outside the cable core through an armoring device to form an aramid armor layer. B. Coating of paraffin: Melt the paraffin, transfer it through a heat-insulating pipeline to a paraffin mold, and coat the surface of the aramid armor layer passing through the paraffin mold with liquid paraffin. C. Winding of non-woven fabric: Through a wrapping device, wind the non-woven fabric around the surface of the aramid armor layer after coating with paraffin to tie the aramid armor layer tightly to form a non-woven fabric layer. Add a heating device to heat the non-woven fabric layer passing through the heating device, so that the paraffin melts again, better infiltrates the aramid and the non-woven fabric, and enhances the interlayer lubrication between the non-woven fabric layer and the aramid armor layer. D. Armoring of the Nth aramid armor layer: Through the above steps, outside the (N - 1)th non-woven fabric layer, armor the Nth aramid armor layer, coat with paraffin, and then wind and heat the Nth non-woven fabric layer to form an armored structure with N layers of aramid armor layers. E. Take-up: Pull the cable core and evenly arrange the armored cable core on the spools of the take-up frame.

7. The production method of the aramid umbilical cable armor structure according to claim 6, characterized in that, The heating device includes a heating sleeve.

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