A method for welding stranded aluminum conductors of submarine cable flexible joints and submarine cable

Abstract

The present invention discloses a method for welding a stranded aluminum conductor of a submarine cable flexible joint and a submarine cable. The method comprises the following steps: S1, cutting the connection end of the stranded aluminum conductor layer by layer; S2, tempering the connection end of the stranded aluminum conductor layer by layer; S3, interlayer integration treatment of the connection end of the linear aluminum conductor: using a flame spray gun to heat and melt the end face of each layer of the connection end at a set inclination angle, so that the layers of the connection end of the linear aluminum conductor are heated and melted into one. S4, positioning the connection end: the two connection ends of the submarine cable are brought into contact, and a welding groove is formed between the two connection ends; S5, preheating before welding; S6, welding of the stranded aluminum conductor; S7, shaping of the welding section. After the connection end of the stranded aluminum conductor is cut layer by layer, the present invention tempers each layer of the strands by powder spraying and heating, which greatly improves the hardness of the connection section after welding and solves the problem of low mechanical strength of aluminum materials after welding.

Description

Technical Field

[0001] The present invention relates to the technical field of cable flexible joints, in particular to a method for welding a stranded aluminum conductor of a submarine cable flexible joint and a submarine cable. Background Art

[0002] DC cables offer high transmission efficiency, low line losses, easy current regulation and power transmission direction change, independent interference between different grid frequencies, and relatively low costs for long-distance lines. They may be the only solution for long-distance submarine power transmission. However, due to limitations in production length and transportation conditions, the length of DC submarine cables may not fully meet the required line length. Therefore, appropriate submarine cable connections must be employed to meet the required line length.

[0003] The cable includes a submarine section installed on the seabed and a landing section installed on land. Although copper conductors outperform aluminum conductors in both physical and electrical properties, considering that the cost of aluminum is much lower than that of copper in the market, the use of aluminum has obvious cost advantages and is lighter in weight. Due to the low temperature of the ocean environment, the conductivity of aluminum is further improved. Therefore, using aluminum as the conductor material in the submarine cable will be more economical, cost-effective and practical.

[0004] In existing technology, after welding and annealing aluminum conductors, the aluminum material at the joint becomes brittle and less flexible, with a material strength of only 70-80. This significantly reduces mechanical strength and makes the aluminum conductors susceptible to breakage at the joint. Therefore, improving the post-weld mechanical strength of stranded aluminum conductors in submarine cable flexible joints remains a pressing technical challenge.

[0005] In addition, in the prior art, stranded aluminum conductors are welded by welding each strand individually, which takes a long time and is particularly prone to breakage for aluminum strands. Summary of the Invention

[0006] The object of the present invention is to provide a method for welding stranded aluminum conductors of a submarine cable flexible joint and a submarine cable capable of improving the mechanical strength of the joint.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A method for welding a stranded aluminum conductor of a submarine cable flexible joint comprises the following steps:

[0009] S1. Layer-by-layer cutting of the stranded aluminum conductor connection end: The stranded aluminum conductor connection end is cut layer by layer from the outer layer to the inner layer, so that the length of the aluminum conductor strands in each layer is equal. In adjacent layers, the length of the aluminum conductor strands in the inner layer is greater than that of the aluminum conductor strands in the outer layer.

[0010] S2. Layer-by-layer quenching and tempering treatment of the connection ends of stranded aluminum conductors;

[0011] S3. Interlayer integration treatment of the connection end of the linear aluminum conductor: Use a flame spray gun to heat and melt the end surface of each layer of the connection end of the twisted aluminum conductor at a set inclination angle, so that the layers of the connection end of the linear aluminum conductor are heated and melted into one;

[0012] S4. Connecting end positioning: Fix the two connecting ends of the submarine cable so that the two connecting ends of the submarine cable are in contact with each other and a welding groove is formed between the two connecting ends;

[0013] S5. Preheating before welding: Use a preheating flame spray gun to preheat the two connecting ends of the submarine cable before welding;

[0014] S6. Stranded aluminum conductor welding: Use welding equipment to weld at the welding groove until the welding material fills the entire welding groove to form a welding section;

[0015] S7. Welding section shaping: Shape the welding section to make it meet the roundness requirements and make the diameter of the welding section equal to the diameter of the two connecting ends of the submarine cable.

[0016] Furthermore, in step S1, after the layer-by-layer cutting is completed, the connection ends of the stranded aluminum conductor form a stepped structure.

[0017] Furthermore, in step S2, the tempering treatment method is as follows: a metal powder spray gun and a tempering flame spray gun are started simultaneously, and metal powder is sprayed along the circumferential direction of each layer of the stranded aluminum conductor connection end while heating, so that the metal powder adheres to the surface of each layer of the stranded aluminum conductor connection end, and the aluminum conductor strands in each layer are heated and melted into one.

[0018] Furthermore, the metal powder is copper powder or magnesium powder.

[0019] Furthermore, in step S1, the stranded aluminum conductor connection end is divided into 9 layers, and the number of aluminum conductor strands in each layer is 1, 6, 12, 18, 24, 30, 36, 42, and 48, from the innermost layer to the outermost layer.

[0020] Furthermore, the length difference of the aluminum conductor strands between adjacent layers is 2-3 cm.

[0021] Furthermore, the temperature of the tempering flame spray gun when performing flame heating on the surface of the connecting end of the stranded aluminum conductor of the submarine cable flexible joint is controlled between 620-640°C.

[0022] Furthermore, in step S5, the temperature of the preheating flame spray gun when performing flame heating on the surface of the connecting end of the stranded aluminum conductor of the submarine cable flexible joint is controlled between 580-600°C.

[0023] Furthermore, in step S6, the welding equipment is arc welding equipment, and the welding temperature is controlled between 1200-3000°C.

[0024] A submarine cable comprises a submarine cable flexible joint manufactured by the stranded aluminum conductor welding method of the submarine cable flexible joint of the present application.

[0025] The beneficial effects of the present invention are:

[0026] The invention performs tempering treatment on each layer of stranded wire by powder spraying and heating after the connection end of the stranded wire aluminum conductor is cut layer by layer, thereby greatly improving the hardness of the connection section after welding and solving the problem of low mechanical strength of the aluminum material after welding.

[0027] The invention heats and melts the strands in the stranded aluminum conductor into a whole, thereby greatly improving the airborne strength of the connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of a method for welding a stranded aluminum conductor of a submarine cable flexible joint according to the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the stranded aluminum conductor connection end after layer-by-layer cutting;

[0030] Figure 3 This is a schematic diagram of the structure of the stranded aluminum conductor after the two connection ends are fixed;

[0031] Figure 4 This is a schematic diagram of the structure of the present invention after the two connecting ends are welded;

[0032] Figure 5 This is a schematic diagram of the structure of the welding section after shaping of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features therein can be combined with each other unless there is a conflict.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper surface", "lower surface", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "forward", "reverse", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0035] Example 1

[0036] like Figure 1 As shown, a method for welding a stranded aluminum conductor of a submarine cable flexible joint comprises the following steps:

[0037] S1. Layer-by-layer cutting of the stranded aluminum conductor connection end: The stranded aluminum conductor connection end is cut layer by layer from the outer layer to the inner layer. The length of the aluminum conductor strands in each layer is equal. In adjacent layers, the length of the aluminum conductor strands in the inner layer is longer than that in the outer layer. The length difference of the aluminum conductor strands between adjacent layers is 2-3cm. After the layer-by-layer cutting is completed, the stranded aluminum conductor connection end forms a stepped structure, such as Figure 2 shown.

[0038] The stranded aluminum conductor connection end is divided into 9 layers. The number of aluminum conductor strands in each layer is 1, 6, 12, 18, 24, 30, 36, 42, and 48 from the innermost layer to the outermost layer.

[0039] S2. Layer-by-layer tempering treatment of the connection ends of stranded aluminum conductors.

[0040] The method of tempering treatment is as follows: start the metal powder spray gun and the tempering flame spray gun at the same time, heat and spray metal powder along the circumferential direction of each layer of the stranded aluminum conductor connection end, so that the metal powder adheres to the surface of each layer of the stranded aluminum conductor connection end, and heats and melts the aluminum conductor strands in each layer into one.

[0041] The metal powder is copper powder.

[0042] The temperature of the tempering flame spray gun when performing flame heating on the surface of the connection end of the stranded aluminum conductor of the submarine cable flexible joint is controlled between 620-640°C.

[0043] S3. Interlayer integration treatment of the connection end of the linear aluminum conductor: Use a flame spray gun to heat and melt the end face of each layer of the connection end of the twisted aluminum conductor at a set inclination angle, so that the layers of the connection end of the linear aluminum conductor are heated and melted into one.

[0044] S4. Positioning the connection ends: Fix the two connection ends 1 of the submarine cable so that the two connection ends of the submarine cable are in contact with each other and a welding groove 2 is formed between the two connection ends. Figure 3 shown.

[0045] S5. Preheating before welding: Use a preheating flame spray gun to preheat the two connecting ends of the submarine cable before welding.

[0046] The temperature of the preheating flame spray gun when performing flame heating on the surface of the connection end of the stranded aluminum conductor of the submarine cable flexible joint is controlled between 580-600°C.

[0047] S6. Welding of stranded aluminum conductor: Use welding equipment to weld at the welding groove until the welding material fills the entire welding groove to form welding section 3, such as Figure 4 The welding equipment is arc welding equipment, and the welding temperature is controlled between 1200-3000°C.

[0048] S7. Welding section shaping: Shape the welding section to make it meet the roundness requirements and make the diameter of the welding section equal to the diameter of the two connecting ends of the submarine cable. Figure 5 shown.

[0049] Example 2

[0050] like Figure 1 As shown, a method for welding a stranded aluminum conductor of a submarine cable flexible joint comprises the following steps:

[0051] S1. Layer-by-layer cutting of the stranded aluminum conductor connection end: The stranded aluminum conductor connection end is cut layer by layer from the outer layer to the inner layer. The length of the aluminum conductor strands in each layer is equal. In adjacent layers, the length of the aluminum conductor strands in the inner layer is longer than that of the aluminum conductor strands in the outer layer. The difference in length of the aluminum conductor strands between adjacent layers is 2-3 cm.

[0052] S2. Layer-by-layer tempering treatment of the connection ends of stranded aluminum conductors.

[0053] The method of tempering treatment is as follows: start the metal powder spray gun and the tempering flame spray gun at the same time, heat and spray metal powder along the circumferential direction of each layer of the stranded aluminum conductor connection end, so that the metal powder adheres to the surface of each layer of the stranded aluminum conductor connection end, and heats and melts the aluminum conductor strands in each layer into one.

[0054] The metal powder is magnesium powder.

[0055] The temperature of the tempering flame spray gun when performing flame heating on the surface of the connection end of the stranded aluminum conductor of the submarine cable flexible joint is controlled between 620-640°C.

[0056] S3. Interlayer integration treatment of the connection end of the linear aluminum conductor: Use a flame spray gun to heat and melt the end face of each layer of the connection end of the twisted aluminum conductor at a set inclination angle, so that the layers of the connection end of the linear aluminum conductor are heated and melted into one.

[0057] S4. Connecting end positioning: Fix the two connecting ends of the submarine cable so that the two connecting ends of the submarine cable are in contact with each other, and a welding groove is formed between the two connecting ends.

[0058] S5. Preheating before welding: Use a preheating flame spray gun to preheat the two connecting ends of the submarine cable before welding.

[0059] The temperature of the preheating flame spray gun when performing flame heating on the surface of the connection end of the stranded aluminum conductor of the submarine cable flexible joint is controlled between 580-600°C.

[0060] S6. Welding of stranded aluminum conductors: Use welding equipment to perform welding at the welding groove until the welding material fills the entire welding groove to form a welding section.

[0061] S7. Welding section shaping: Shape the welding section to make it meet the roundness requirements and make the diameter of the welding section equal to the diameter of the two connecting ends of the submarine cable.

[0062] In the above-mentioned embodiment 1, the connection ends of the stranded aluminum conductor are subjected to layer-by-layer quenching and tempering treatment using copper powder; in the above-mentioned embodiment 2, the connection ends of the stranded aluminum conductor are subjected to layer-by-layer quenching and tempering treatment using magnesium powder.

[0063] A submarine cable comprises a submarine cable flexible joint manufactured by the stranded aluminum conductor welding method of the submarine cable flexible joint in embodiment 1 or embodiment 2.

[0064] Working Principle: After the stranded aluminum conductor connection end is cut layer by layer, the present invention performs a tempering treatment on each layer of stranded wire by powder spraying and heating. Metal powder is sprayed while heating, so that the metal powder adheres to the surface of each layer of the stranded aluminum conductor connection end. The metal powder is copper powder or magnesium powder, so that the aluminum conductor connection section is changed from pure aluminum to copper-containing aluminum alloy, which greatly improves the hardness of the connection section after welding and solves the problem of low mechanical strength of aluminum material after welding.

[0065] In the prior art, stranded aluminum conductors are welded one strand at a time, which takes a long time and makes the aluminum strands more prone to breakage. The present invention heats and melts the individual strands in the stranded aluminum conductor into a single unit, greatly improving the airborne strength of the joint.

[0066] In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent. Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for welding stranded aluminum conductors of submarine cable flexible joints, characterized in that: The following steps are involved: S1. Layer-by-layer cutting of the stranded aluminum conductor connection end: The stranded aluminum conductor connection end is cut layer by layer from the outer layer to the inner layer, so that the length of the aluminum conductor strands in each layer is equal. In adjacent layers, the length of the aluminum conductor strands in the inner layer is greater than that of the aluminum conductor strands in the outer layer. S2. Tempering the stranded aluminum conductor connection end layer by layer: The tempering treatment method is as follows: Simultaneously activate the metal powder spray gun and the tempering flame spray gun, spraying metal powder along the circumference of each layer of the stranded aluminum conductor connection end while heating, so that the metal powder adheres to the surface of each layer of the stranded aluminum conductor connection end, and heats and fuses the aluminum conductor strands in each layer into one. S3. Interlayer integration treatment of the connection end of the linear aluminum conductor: Use a flame spray gun to heat and melt the end surface of each layer of the connection end of the twisted aluminum conductor at a set inclination angle, so that the layers of the connection end of the linear aluminum conductor are heated and melted into one; S4. Connecting end positioning: Fix the two connecting ends of the submarine cable so that the two connecting ends of the submarine cable are in contact with each other and a welding groove is formed between the two connecting ends; S5. Preheating before welding: Use a preheating flame spray gun to preheat the two connecting ends of the submarine cable before welding; S6. Stranded aluminum conductor welding: Use welding equipment to weld at the welding groove until the welding material fills the entire welding groove to form a welding section; S7. Welding section shaping: Shape the welding section to make it meet the roundness requirements and make the diameter of the welding section equal to the diameter of the two connecting ends of the submarine cable.

2. The method for welding stranded aluminum conductors of submarine cable flexible joints according to claim 1, characterized in that: In step S1, after the layer-by-layer cutting is completed, the connection ends of the stranded aluminum conductor form a stepped structure.

3. The method for welding stranded aluminum conductors of submarine cable flexible joints according to claim 2, characterized in that: The metal powder is copper powder or magnesium powder.

4. The method for welding stranded aluminum conductors of submarine cable flexible joints according to claim 1, characterized in that: In step S1, the stranded aluminum conductor connection end is divided into 9 layers, and the number of aluminum conductor strands in each layer is 1, 6, 12, 18, 24, 30, 36, 42, and 48, from the innermost layer to the outermost layer.

5. The method for welding stranded aluminum conductors of submarine cable flexible joints according to claim 1, characterized in that: The difference in length of the aluminum conductor strands between adjacent layers is 2-3 cm.

6. The method for welding stranded aluminum conductors of submarine cable flexible joints according to claim 1, characterized in that: The temperature of the tempering flame spray gun when performing flame heating on the surface of the connection end of the stranded aluminum conductor of the submarine cable flexible joint is controlled between 620-640°C.

7. The method for welding stranded aluminum conductors of submarine cable flexible joints according to claim 1, characterized in that: In step S5, the temperature of the preheating flame spray gun when performing flame heating on the surface of the connecting end of the stranded aluminum conductor of the submarine cable flexible joint is controlled between 580-600°C.

8. The method for welding stranded aluminum conductors of submarine cable flexible joints according to claim 1, characterized in that: In step S6, the welding equipment is arc welding equipment, and the welding temperature is controlled between 1200-3000°C.

9. A submarine cable, characterized in that: The flexible cable joint comprises a flexible cable joint made by utilizing any one of claims 1 to 8.

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