A method of welding a copper-steel hybrid armour for a submarine cable and an armour layer for a submarine cable

Abstract

The application discloses a submarine cable copper-steel mixed armoring welding method and a submarine cable armoring layer, and the method comprises the following steps: a straightening treatment step, a flat mouth treatment step, an opening bevel step, a cleaning step, a first centering step, a first soldering step, a first welding step, a second centering step, a second soldering step, a second welding step and a polishing step. The welding method adopts brass wire as an intermediate medium to weld copper wire and steel wire, avoids direct welding of the copper wire and the steel wire, makes the mechanical performance of the mixed metal wire after welding good, has high tensile strength, and has excellent bending performance. The welding method is simple to operate and fast in welding speed. The application adopts copper-steel mixed armoring as the submarine cable armoring layer, can reduce metal loss, improve local current-carrying capacity, reduce unnecessary high cost, adopts copper wire in a place where the local working condition thermal resistance is high, and can improve the matching of the submarine cable current-carrying capacity.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a method for welding copper-steel hybrid armor of submarine cables and an armor layer for submarine cables. Background Technology

[0002] Submarine cables (submarine cables) are cables laid on the seabed, mainly used for power transmission. They are primarily used in fields such as long-distance connections between islands, between mainland islands, cross-sea military facilities, offshore wind power generation and transmission, and offshore oil platforms.

[0003] Currently, offshore wind power projects are developing rapidly as a new energy project, and long-length high-voltage submarine cables are widely used in these projects, undertaking the task of large-capacity, high-voltage, and long-distance power transmission. Reducing losses, increasing current carrying capacity, and enhancing transmission capacity in long-length high-voltage submarine cables have become key technologies driving the development of long-distance transmission lines. In offshore wind power projects, the laying environment for submarine cables is harsh and varied, leading to a wide variety of laying methods. These methods include air laying, cable trench laying, J-tube laying, submarine laying, landing section tidal flat laying, and landing section seawall laying. Under different laying environments, the thermal resistance of the environmental areas varies, affecting the current carrying capacity of the armored submarine cables.

[0004] In the process of implementing the technical method of the embodiments of this invention, the inventors of this patent have discovered at least the following technical problems in the prior art:

[0005] Existing submarine cables are generally armored with a single metal material, with steel wire armor being the most common. The high metal loss coefficient of steel wire armor has long constrained the ability to increase the transmission capacity of long-length high-voltage submarine cables. Furthermore, the existing steel wire armor layers of submarine cables face challenges due to varying thermal resistance in different laying methods and environments, affecting the current-carrying capacity of the armored cables. This results in insufficient current-carrying capacity matching, and localized insufficient current-carrying capacity limiting the overall current-carrying capacity of the cable.

[0006] Due to limitations in armor materials, long-length high-voltage submarine cables cannot meet the demand for higher transmission capacity, making it particularly important to reduce armor loss. Although using copper wire armor for long-length high-voltage submarine cables can significantly reduce loss and increase current carrying capacity, using copper wire armor for the entire cable would increase unnecessary and high costs.

[0007] The option of using both copper and steel for the armor of submarine cables has been considered. However, the significant differences in melting point, thermal conductivity, and coefficient of linear expansion between copper and steel have made the welding process a persistent technical challenge. Furthermore, the small diameter of the steel and copper wires used in the cable armor layers further complicates achieving superior mechanical properties. Existing copper-steel welding methods, such as current butt welding or oxy-fuel welding, suffer from the poor fluidity of copper and steel, resulting in suboptimal mechanical properties (tensile strength, bending performance) in the welding wires. These methods fail to meet the complex requirements of submarine cable laying and operation.

[0008] In summary, existing copper-steel welding methods cannot meet practical application requirements. Summary of the Invention

[0009] This invention provides a method for welding copper-steel hybrid armor for submarine cables and a submarine cable armor layer, which solves the problem that existing copper-steel welding methods cannot meet practical application requirements.

[0010] One embodiment of the present invention provides a method for welding copper-steel hybrid armor for submarine cables, comprising:

[0011] Straightening process: The steel wire, copper wire and brass wire are straightened separately;

[0012] Flat-end processing steps: Vertically cut the ends of the straightened steel wire, copper wire, and brass wire;

[0013] Beveling steps: Beveling the ends of steel wire, copper wire, and brass wire that have been flattened;

[0014] Cleaning steps: Remove impurities from the bevel of the steel wire, copper wire, and brass wire after beveling;

[0015] First alignment step: Align the cleaned steel wire and brass wire longitudinally, and fit the bevels of the steel wire and brass wire tightly together;

[0016] Initial soldering steps: Insert silver solder pads between the steel wire and the brass wire for soldering;

[0017] Initial welding steps: Perform UN butt welding on the steel wire and brass wire;

[0018] Secondary alignment step: Align the copper wire and brass wire longitudinally, and tightly fit the bevels of the copper wire and brass wire together;

[0019] Secondary fluxing step: Use silver solder to flux the solder;

[0020] Secondary welding step: Argon arc welding is performed on the copper wire and brass wire;

[0021] Grinding steps: Grind the welded area to ensure that the outer diameter of the welded area does not exceed 1.05 times the outer diameter of the steel wire, copper wire, and brass wire.

[0022] Optionally, after the polishing step, the process may further include:

[0023] Assembly steps: The polished mixed metal wires are welded together with steel wires and copper wires on a submarine cable wire armoring machine to form the submarine cable armor layer.

[0024] Optionally, the silver solder sheet in the first fluxing step is specifically 40%~60% silver solder sheet, and the silver solder rod in the second fluxing step is specifically 10%~30% silver solder rod.

[0025] Optionally, the beveling angle on one side in the beveling step is 50°-60°.

[0026] Optionally, the initial welding step specifically includes:

[0027] Set the welding current of the UN-type butt welding machine to 60A~80A;

[0028] Press the start button on the UN-type butt welding machine to perform UN butt welding.

[0029] Optionally, the secondary welding step specifically includes:

[0030] Set the welding current for argon arc welding to 75A~95A;

[0031] Start welding with the argon arc welding torch 4-5 cm from the copper wire section at the connection point, and move the argon arc welding torch at a constant speed of 1 cm / s to perform argon arc welding.

[0032] On the other hand, embodiments of the present invention also provide a submarine cable armor layer prepared using the copper-steel hybrid armor welding method for submarine cables described in the foregoing embodiments, the armor layer comprising:

[0033] steel wire;

[0034] A brass wire, the first end of which is butt-welded to the second end UN of the steel wire;

[0035] A copper wire, the first end of which is argon-arc welded to the second end of the brass wire.

[0036] Optionally, the steel wire is specifically a galvanized steel wire with a diameter of 3mm-9mm.

[0037] Optionally, the brass wire segment is specifically an H65 brass wire with a diameter of 3mm-9mm.

[0038] Optionally, the copper wire segment is specifically a hard copper wire with a diameter of 3mm-9mm.

[0039] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0040] Because copper and steel have significant differences in melting point, thermal conductivity, and coefficient of thermal expansion, direct welding of copper and steel wires would result in a mixed metal wire whose mechanical properties would not meet practical application requirements. Therefore, the welding method of this invention uses brass wire as an intermediate medium to weld the copper and steel wires, avoiding direct welding. This results in a mixed metal wire with good mechanical properties, high tensile strength, and excellent bending performance. This solves the technical problems of small diameter steel and copper wires, easy breakage of copper-steel joints, and inability to meet the complex operating conditions faced by submarine cable laying and operation. Furthermore, the weld surface has good quality, free from defects such as incomplete penetration, fusion, cracks, porosity, and slag inclusions. In addition, the welding method of this invention is simple to operate and fast. Bending performance tests have shown that the welded mixed metal wire, when wound multiple times on a 10mm diameter rod, did not experience breakage or cracking at the weld. Tensile strength testing of the welded mixed metal wire showed that its tensile strength was not less than 95% of the original wire.

[0041] The submarine cable armor layer of this invention includes copper wire, steel wire, and brass wire. Compared with submarine cables that use only copper wire, it can reduce metal loss, increase local current carrying capacity, and reduce high unnecessary costs. This invention uses a copper-steel hybrid as the submarine cable armor layer. Compared with traditional submarine cables that use a single metal material, it can solve the problem of insufficient transmission capacity in local submarine cable laying. Using copper wire in areas with high local thermal resistance can improve the matching of current carrying capacity of the submarine cable. Attached Figure Description

[0042] Figure 1 This is a flowchart of a copper-steel hybrid armor welding method for submarine cables according to an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of steel wire and brass wire being welded together in one embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of copper wire and brass wire being welded together in one embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of steel wire, copper wire, and brass wire after welding is completed in one embodiment of the present invention. Detailed Implementation

[0046] This invention provides a method for welding copper-steel hybrid armor for submarine cables and a submarine cable armor layer, solving the problems associated with a method for welding copper-steel hybrid armor for submarine cables and a submarine cable armor layer.

[0047] To better understand the above-described method for welding copper-steel hybrid armor for submarine cables and the submarine cable armor layer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described in this invention are only some, not all, of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0048] Because copper and steel have significant differences in melting point, thermal conductivity, and coefficient of thermal expansion—for example, copper has a melting point of 1083℃ while steel has a melting point of 1400℃; copper has a thermal conductivity of 284.7 W / m·K while steel has a thermal conductivity of 54.4 W / m·K—if copper wire and steel wire are directly welded, the mechanical properties of the resulting mixed metal wire cannot meet the requirements for practical use. Therefore, the welding method of this invention uses brass wire as an intermediate medium to weld copper wire and steel wire, avoiding direct welding of copper wire and steel wire.

[0049] Please refer to the following. Figure 1 The present invention describes in detail a method for welding copper-steel hybrid armor for submarine cables, which includes a straightening process, a flat-end process, a beveling process, a cleaning process, a first alignment process, a first welding process, a first welding process, a second alignment process, a second welding process, a second welding process, and a grinding process.

[0050] Straightening process: The steel wire, copper wire and brass wire are straightened separately.

[0051] The straightening process involves, for example, using pliers to straighten the steel wire, copper wire, and brass wire separately. The diameters of the steel wire, copper wire, and brass wire are all between 3mm and 9mm. The steel, copper, and brass wires are of equal diameter, specifically 6mm. The cut lengths of both the copper and steel wires are 30cm. To ensure even alignment during welding, the steel, copper, and brass wires are ground separately using a grinding wheel.

[0052] Flat-end processing steps: Vertically cut the ends of the straightened steel wire, copper wire, and brass wire.

[0053] In practice, the flat-end processing step involves, for example, using a cutting machine to process the ends of straightened steel wires, copper wires, and brass wires to form a flat, smooth surface, thereby improving the connection performance.

[0054] Beveling steps: Beveling the ends of steel wire, copper wire, and brass wire that have been flattened before welding.

[0055] In practice, the beveling process involves, for example, before welding, using mechanical, flame, or electric arc methods to cut or grind the flat-end steel, copper, or brass wire to be welded, creating a V-shaped bevel. The main purpose of beveling is to increase the depth and width of the weld, promote the flow of welding materials, reduce welding stress, and thus improve the strength and durability of the welded joint.

[0056] Preferably, the single-sided angle of the bevel is 50°-60°. Within this angle range, it can achieve good penetration, reduce the depth of non-fusion, enhance weld strength, reduce the amount of filler, shorten welding time, reduce material waste, and improve material utilization.

[0057] Cleaning steps: Remove impurities from the bevel of the steel wire, copper wire, and brass wire after beveling.

[0058] In the specific implementation of the cleaning steps, for example, use a scouring pad to wipe the steel wire, copper wire and brass wire separately, and use a special alcohol cleaning cloth soaked in anhydrous ethanol to wipe the steel wire, copper wire and brass wire separately to ensure that the area within 20mm of the end to be welded is smooth, clean, free of oil, visible fibers or metal burrs and other substances, so as to avoid impurities being trapped in the weld, which would cause porosity, weaken the weld strength and lead to welding failure.

[0059] First alignment step: Align the cleaned steel wire and brass wire longitudinally, and fit the bevels of the steel wire and brass wire tightly together.

[0060] The initial alignment step, in practice, involves selecting a suitable fixture and adjusting the jaw distance. The cleaned steel wire and brass wire are then mounted on the welding table fixture, aligned longitudinally, and their bevels are tightly fitted together. The bevels of the steel and brass wires are V-shaped; after alignment, they form an X-shape. This ensures penetration during welding, prevents misalignment, and guarantees weld strength.

[0061] Initial soldering steps: Insert silver solder pads between the steel wire and the brass wire for soldering.

[0062] The initial fluxing step, in specific implementation processes, for example: Figure 2 and Figure 4 As shown, the silver solder sheet is placed between the bevels of the steel wire and the brass wire to facilitate subsequent UN butt welding. Using the silver solder sheet as a flux material ensures good bonding between silver atoms and the steel and brass wires, guaranteeing the strength of the weld.

[0063] Preferably, the silver solder sheet in the initial fluxing step is 40% to 60% silver solder sheet. The 40% to 60% silver solder sheet can maintain the excellent electrical conductivity, thermal conductivity and corrosion resistance of silver, while also having good processing performance and cost-effectiveness, and has a low melting point, good fluidity and filling properties, high strength and corrosion resistance.

[0064] Initial welding procedure: Perform UN butt welding on the steel wire and brass wire. The initial welding procedure specifically includes: setting the welding current of the UN type butt welding machine to 60A~80A; activating the start button of the UN type butt welding machine to perform UN butt welding.

[0065] The initial welding process involves, for example: First, checking that the UN-type butt welding machine is working properly and ensuring it is in good condition. Then, setting the welding current of the UN-type butt welding machine to 60A~80A and starting the machine to complete the welding in one pass. After the UN butt welding is completed, the molten pool gradually cools and solidifies, forming a welded joint. Since the melting point of steel wire is approximately 1400℃ and that of brass wire is approximately 850℃, current butt welding requires utilizing the difference in heating rate caused by resistivity to complete the welding in one pass; otherwise, the brass will react, causing structural damage and pulverization, severely affecting the mechanical properties of the weld. The molten medium of silver brazing helps the flow and displacement of steel and brass, resulting in superior welding effects. Compared to direct welding without silver brazing, welding with silver brazing significantly improves tensile strength and bending performance.

[0066] Secondary alignment step: Align the copper wire and brass wire longitudinally and fit the bevels of the copper wire and brass wire tightly together.

[0067] In the specific implementation of the secondary alignment step, for example: selecting a suitable fixture and adjusting the jaw distance, mounting the cleaned copper and brass wires onto the welding table fixture, aligning the copper and brass wires longitudinally, and ensuring their bevels are tightly fitted together. The bevels of the copper and brass wires are V-shaped; after alignment, the two bevels form an X-shape, ensuring weld penetration during welding, preventing misalignment, and guaranteeing weld strength.

[0068] Secondary fluxing step: Use silver solder to flux the solder.

[0069] In the specific implementation process, the secondary fluxing step is, for example: Figure 3 and Figure 4 As shown, the silver solder is placed near the bevels of the copper and brass wires to facilitate subsequent argon arc welding. Using silver solder as a flux material ensures good bonding between silver atoms and the copper and brass wires, guaranteeing the strength of the weld.

[0070] Preferably, the silver solder used in the secondary fluxing step is a 10% to 30% silver solder. A 10% to 30% silver solder possesses excellent electrical conductivity, excellent weld strength and ductility, good wettability and filling ability, a moderate melting point, lower production costs, and good environmental friendliness.

[0071] Secondary welding step: Argon arc welding is performed on the copper wire and brass wire. The secondary welding step specifically includes: setting the welding current of argon arc welding to 75A~95A; starting welding with the argon arc welding torch 4cm-5cm away from the joint of the copper wire segment, and moving the argon arc welding torch at a uniform speed of 1cm / s to perform argon arc welding.

[0072] In the specific implementation of the secondary welding step, for example: First, confirm the welding parameters, including welding current, nozzle diameter, and gas flow rate, and set the welding current to 75A~95A. Next, perform steps such as arc ignition, wire feeding, welding torch movement, molten pool control, welding speed control, and weld joint treatment to complete the argon arc welding. Specifically, the argon arc welding torch begins welding 4cm-5cm from the joint on the copper wire section, moving at a uniform speed of 1cm / s to the welding point and adding silver solder. Since the melting point of copper wire is approximately 1000℃ and that of brass wire is approximately 850℃, their melting rates differ during argon arc welding. Heating begins on the copper wire side, and as the torch slowly moves to the welding point, the brass wire begins to melt. At this point, the silver solder is added, and heating ends. The molten medium of the silver solder facilitates the flow and displacement of copper and brass, resulting in superior welding performance. Compared to welding with other electrodes, welding with silver solder significantly improves tensile strength and bending performance.

[0073] Grinding steps: Grind the welded area to ensure that the outer diameter of the welded area does not exceed 1.05 times the outer diameter of the steel wire, copper wire, and brass wire.

[0074] In the specific implementation process, the grinding step involves, for example, using a grinding wheel to smooth the raised weld seam, ensuring that the outer diameter of the weld does not exceed 1.05 times the outer diameter of the steel wire, copper wire, and brass wire. This helps maintain the overall dimensional accuracy and consistency of the mixed metal wires after welding, resulting in uniform stress on the formed armor layer. Grinding the weld seam also removes impurities, improves weld accuracy, and reduces stress concentration. Care must be taken to avoid damaging the steel and copper wires during grinding to ensure the tensile strength of each wire after welding. The tensile strength of the welded mixed metal wire, tested with a tensile testing machine, should not be less than 95% of the original metal wire, and the fracture point should be located in the heat-affected zone on the copper wire side.

[0075] Following the grinding step, there is also an assembly step: the ground mixed metal wires are welded together with steel wires and copper wires on a submarine cable wire armoring machine to form the submarine cable armor layer.

[0076] In the assembly process, for example, after grinding, the mixed metal wires are welded together with steel and copper wires on a submarine cable wire armoring machine to form the submarine cable armor layer, ensuring production continuity, guaranteeing armor layer strength, and protecting the submarine cable from damage. The mixed metal wires are tightly wound or braided around the outside of the submarine cable core at a specific twist angle and spacing. This process requires precise control of the tension, twist angle, and spacing of the mixed metal wires to ensure the uniformity and stability of the armor layer. Furthermore, after the mixed metal wires are wound or braided, materials such as polyethylene pipes may be used to further reinforce and protect the armor layer, increasing its mechanical strength and corrosion resistance.

[0077] This invention also provides a submarine cable armor layer prepared using the copper-steel hybrid armor welding method described in the foregoing embodiments, the armor layer comprising:

[0078] steel wire;

[0079] The first end of the brass wire is welded to the second end of the steel wire.

[0080] The first end of the copper wire is welded to the second end of the brass wire.

[0081] Preferably, the steel wire is a galvanized steel wire with a diameter between 3mm and 9mm. Galvanized steel wire has advantages such as strong corrosion resistance, excellent physical properties, good processing performance, and low cost. Specifically, this invention selects a steel wire with a diameter of 6mm. In practical applications, steel wires of different diameters can be selected according to specific needs, such as 3mm, 5mm, 9mm, etc., and this invention is not limited thereto.

[0082] Preferably, the brass wire is H65 brass wire with a diameter between 3mm and 9mm. H65 brass wire has advantages such as excellent mechanical properties, excellent processing performance, and good corrosion resistance. Specifically, this invention selects brass wire with a diameter of 6mm. In practical applications, brass wires of different diameters can be selected according to specific needs, such as 4mm, 5mm, 7mm, etc. Other types of brass wire can be used, and this invention is not limited thereto.

[0083] Preferably, the copper wire is a hard copper wire with a diameter between 3mm and 9mm. Hard copper wire has advantages such as good conductivity, high durability, good flame retardancy, easy installation, relatively low price, and high current stability. Specifically, this invention uses a copper wire with a diameter of 6mm. In practical applications, copper wires of different diameters can be selected according to specific needs, such as 3mm, 5mm, 8mm, etc., and this invention is not limited thereto.

[0084] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method of welding a copper-steel hybrid armour for a submarine cable, characterized in that, The method comprises the following steps: a straightening step of straightening the steel wire, the copper wire and the brass wire respectively; a flat end processing step of vertically cutting the end of the straightened steel wire, copper wire and brass wire; a beveling step of beveling the end to be welded of the flat end processed steel wire, copper wire and brass wire; a cleaning step of removing impurities at the bevel of the beveled steel wire, copper wire and brass wire; a first centering step of longitudinally centering the cleaned steel wire and brass wire, and tightly fitting the bevels of the steel wire and brass wire; a first soldering step of clamping a silver soldering sheet between the steel wire and the brass wire for soldering; a first welding step of UN butt welding the steel wire and the brass wire; a second centering step of longitudinally centering the copper wire and the brass wire, and tightly fitting the bevels of the copper wire and the brass wire; a second soldering step of soldering by using a silver soldering rod; a second welding step of argon arc welding the copper wire and the brass wire; a polishing step of polishing the welded part, so that the outer diameter of the welded part is not more than 1.05 times the outer diameter of the steel wire, copper wire and brass wire.

2. The method of claim 1, wherein, After the polishing step, the method further comprises: an assembling step of welding the polished mixed metal wire with the steel wire and the copper wire on a submarine cable steel wire armoring machine to form a submarine cable armoring layer.

3. The method of claim 1, wherein, The silver soldering sheet in the first soldering step is specifically a 40%-60% silver soldering sheet, and the silver soldering rod in the second soldering step is specifically a 10%-30% silver soldering rod.

4. The method of claim 1, wherein, The single-side angle of the bevel in the beveling step is 50°-60°.

5. The method of claim 1, wherein, The first welding step specifically comprises: setting the welding current of the UN butt welding machine to 60A-80A; starting the start button of the UN butt welding machine to perform UN butt welding.

6. The method of claim 1, wherein, The second welding step specifically comprises: setting the welding current of the argon arc welding to 75A-95A; starting welding at a position 4cm-5cm away from the connection of the copper wire section, and moving the argon arc welding gun at a speed of 1cm / s to perform argon arc welding.

7. A submarine cable armouring layer prepared by the method of welding a copper-steel hybrid armouring of a submarine cable according to any one of claims 1 to 6, characterized in that, The armoring layer comprises: a steel wire; a brass wire, a first end of which is UN butt welded with a second end of the steel wire; a copper wire, a first end of which is argon arc welded with a second end of the brass wire.

8. An armoured layer according to claim 7, wherein, The steel wire is specifically a galvanized steel wire with a diameter of 3mm-9mm.

9. The armored layer of claim 7, wherein, The brass wire section is specifically an H65 brass wire with a diameter of 3mm-9mm.

10. The armored layer of claim 7, wherein, The copper wire section is specifically a hard copper wire with a diameter of 3mm-9mm.

Images