A method for preparing polygonal monofilament of submarine cable

Abstract

A method for preparing polygonal monofilaments for submarine cables belongs to the technical field of submarine cables. It includes: determining the approximate area of ​​the monofilament cross section, determining the chamfer radius of the regular polygon; determining the circumscribed circle diameter of the regular polygon where the monofilament cross section is located, selecting a combination of existing circular monofilament drawing dies with a diameter close to the circumscribed circle diameter; replacing the dies in the last few passes of the monofilament drawing process; drawing the monofilament, and adjusting the annealing coefficient of the wire drawing machine and the production line speed according to the structure of the monofilament during the drawing process. The present invention increases the stability of the conductor structure by designing a polygonal special-shaped monofilament to replace the original trapezoidal and Z / S-shaped wires, and avoids the problems of difficult design and manufacturing of traditional shaped wire monofilaments; by chamfering the corners, it is convenient to fill the water-blocking material, meeting the requirements of water-blocking conductors.

Description

Technical Field

[0001] The invention relates to a method for preparing a polygonal monofilament of a submarine cable, belonging to the technical field of submarine cables. Background Art

[0002] In recent years, with the rapid development of offshore wind power projects, demand for medium- and high-voltage submarine cables and fiber-optic composite submarine cables has increased significantly. Submarine cable conductors are typically constructed from multiple round monofilaments twisted together in a compressed circular structure. As the conductor cross-section increases, the compression coefficient decreases, negatively impacting both the cable's production process and economic costs. Consequently, the industry has begun adopting a shaped-wire conductor structure with a higher fill factor. This structure differs primarily from the compressed circular structure in the shape of the twisted monofilaments, effectively increasing the conductor's compression coefficient and reducing its outer diameter.

[0003] However, the design and production of shaped monofilaments are very complicated, especially the need to pay attention to the state of the monofilaments at all times during production; at the same time, traditional shaped monofilaments mostly use trapezoidal and Z / S-shaped wires. Since the sizes of each layer of monofilaments are different, multiple sets of drawing dies are required, and the remaining monofilaments are not easy to store, which brings great difficulties to the production of special-shaped monofilaments. Summary of the Invention

[0004] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and provide a method for preparing polygonal monofilaments for submarine cables. The monofilaments prepared by the present invention have a regular polygonal special-shaped structure, which not only has the advantages of a high compression coefficient of the profiled conductor and a small outer diameter, but also can make use of the existing circular monofilament drawing mold, thereby saving costs.

[0005] The technical solutions of the present invention are as follows:

[0006] A method for preparing a polygonal monofilament of a submarine cable is characterized by comprising the following steps:

[0007] (1) Monofilament design

[0008] ① Determine the approximate cross-sectional area S1 of the single wire according to the performance parameters of the cable (determine the approximate cross-sectional area S1 of the single wire according to the resistance value of the cable, the number of single wires in the cable, and the material of the single wire);

[0009] ② The cross section of the monofilament is a regular polygonal structure, and the chamfer radius r of the regular polygon is determined according to the approximate cross section area S1 of the monofilament;

[0010] ③ Determine the diameter d of the circumscribed circle of the regular polygon where the monofilament cross section is located;

[0011] (2) Monofilament processing

[0012] ① According to the diameter d of the circumscribed circle of the regular polygon where the monofilament cross section is located, select an existing circular monofilament drawing die combination with a diameter close to the circumscribed circle diameter d (select a circular monofilament drawing die close to d to make full use of the existing circular monofilament drawing die);

[0013] ② For the dies used in the last n passes of the monofilament drawing process, replace them with corresponding regular polygonal monofilament drawing dies (reasonably match the dies according to the area reduction ratio, and selectively replace the dies used in the last few passes); where m is a natural number and m ≥ 1;

[0014] ③Draw the single wire. During the drawing process, adjust the annealing coefficient of the wire drawing machine and the production line speed according to the structure of the single wire.

[0015] The special-shaped monofilament structure adopted in the present invention has a cross-section of a (quasi-) regular polygonal structure, which is convenient for drawing and can also avoid quality problems such as flipping during the production process; chamfering is performed on the corners of the regular polygon, which is convenient for production and filling of water-blocking materials, and can also avoid the occurrence of tip discharge when applied to high-voltage lines; during processing, one or two special-shaped monofilament drawing dies can be selectively added to the existing circular monofilament drawing die, so that monofilaments of different specifications can be quickly drawn.

[0016] Furthermore, since the size of the chamfer directly affects the actual production difficulty and the final compression coefficient of the special-shaped monofilament, the smaller the difference between the approximate area of ​​the monofilament cross section and the actual area, the smaller the chamfer radius should be. Therefore, in the preliminary design process, the chamfer radius is first determined according to the required approximate area of ​​the monofilament cross section according to Table 1 below:

[0017]

[0018] Table 1 Relationship between the approximate cross-sectional area of ​​regular polygonal monofilament and chamfer

[0019] Furthermore, in step (1), determining the diameter d of the circumscribed circle of the regular polygon in which the monofilament cross section is located comprises the following steps:

[0020] A. Given the approximate cross-sectional area S1 of a single wire and the number of sides of a regular polygon n, calculate the approximate diameter d1 of the circumscribed circle using the following regular polygon area formula:

[0021]

[0022] B. Given the approximate diameter d1 of the circumscribed circle, the chamfer radius r, and the number of sides of the regular polygon, use the "BO" command in CAD software to calculate the approximate cross-sectional area S'1 of the single wire;

[0023] C. Since the approximate cross-sectional area of ​​the single wire S′1 is smaller than the approximate cross-sectional area of ​​the single wire S1, in order to maximize the approximate area close to S1, and considering that the dimensional processing accuracy of the drawing die in the diameter direction is controlled within 0.01 mm, the approximate diameter of the circumscribed circle is set to d2 = d1 + 0.01;

[0024] Given the approximate diameter d2 of the circumscribed circle, the chamfer radius r, and the number of sides of the regular polygon, use the "BO" command in the CAD drawing software to calculate the approximate cross-sectional area S2 of the single wire;

[0025] D. Select the value closest to the approximate area S1 from S′1 and S2 as the final monofilament cross-sectional area S, and the corresponding circumscribed circle diameter as the final circumscribed circle diameter d, and register and name it.

[0026] Furthermore, in step (2), the annealing coefficient is adjusted according to Q=k1·Q0, wherein Q is the annealing coefficient of the polygonal monofilament, Q0 is the annealing coefficient of an existing circular monofilament close to the circumscribed circle diameter d, and k1 is the ratio of the cross-sectional perimeter of the existing circular monofilament to the cross-sectional perimeter of the polygonal monofilament. The production line speed is adjusted according to V=K2·V0, wherein V is the production line speed of the polygonal monofilament, V0 is the production line speed of an existing circular monofilament close to the circumscribed circle diameter d, and K2 is the ratio of the cross-sectional area of ​​the polygonal monofilament to the cross-sectional area of ​​the existing circular monofilament.

[0027] After monofilament drawing, cold deformation of the metal creates internal stresses in the conductor, potentially degrading its electrical performance. To reduce these stresses, the monofilaments are typically annealed. In traditional shaped monofilament drawing, existing annealing protocols for round monofilaments are inappropriate for these applications, and can easily lead to incomplete or even over-annealing, impacting product quality. Operators often rely on prior experience to adjust the process, resulting in inconsistent results.

[0028] The annealing temperature of traditional shaped monofilaments is generally higher than that of ordinary round monofilaments. This is because the cross-sectional shape of the shaped monofilaments is irregular and the internal stresses are relatively complex, so higher temperatures are required to eliminate these stresses. In the present invention, the structure of the regular polygonal monofilaments is symmetrical and similar to a circle. Its internal structure and stress are simpler than those of traditional shaped monofilaments. Therefore, an existing circular monofilament annealing scheme with a similar circumscribed circle can be selected, and adaptive production improvements based on this scheme can be made, which can greatly reduce the difficulty of monofilament drawing. By adjusting the annealing coefficient, production line speed, etc., the present invention can avoid the quality problems caused by relying on experience to debug equipment parameters during the processing of existing shaped monofilaments.

[0029] In addition, due to the complex structure of the profile, there are too many influencing factors when matching the mold, and the actual production will increase the number of drawing passes, which cannot fully exert the ductility of the material. Since the present invention uses regular polygonal monofilaments, the structure is symmetrical and simple, and the ductility of the material can be fully exerted when matching the mold, just like drawing circular monofilaments, so the present invention can directly use the front circular mold and only replace the following passes with regular polygonal molds.

[0030] Compared with the existing technology, the present invention increases the stability of the conductor structure by designing a polygonal special-shaped monofilament to replace the original trapezoidal and Z / S-shaped wires, while avoiding the problems of difficult design and manufacturing of traditional monofilament wires; by chamfering the corners, it is convenient to fill the water-blocking material, meeting the requirements of water-blocking conductors. The processing method of the present invention can, firstly, be quickly improved on the basis of existing equipment, so that the equipment has the ability to quickly draw this type of monofilament; secondly, the present invention can systematically adjust the equipment parameters, avoiding the quality problems caused by the original processing method, and at the same time can fully improve the equipment production capacity; thirdly, it can make use of the existing circular monofilament drawing mold, greatly saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the cross-sectional structure of a regular hexagonal monofilament in an embodiment of the present invention;

[0032] In the figure: 1. Special-shaped monofilament; 2. Chamfer of special-shaped monofilament; 3. Circumscribed circle of special-shaped monofilament. DETAILED DESCRIPTION

[0033] Example 1

[0034] A method for preparing a polygonal monofilament for a submarine cable includes two parts: designing and processing a regular polygonal monofilament, wherein:

[0035] 1. Design of regular polygonal monofilament

[0036] S1: Determine the approximate cross-sectional area S1 of the single-filament according to the resistance value of the cable, the number of single-filaments in the cable, the material of the single-filaments and other parameters;

[0037] S2: The cross section of the monofilament is a regular polygon. The chamfer radius r of the regular polygon is determined based on the approximate cross section area S1 of the monofilament:

[0038]

[0039] Table 1 Relationship between the approximate cross-sectional area of ​​regular polygonal monofilament and chamfer

[0040] S3: Given the approximate cross-sectional area S1 of the monofilament and the number of sides of the regular polygon n, calculate the approximate diameter d1 of the circumscribed circle using the following regular polygon area formula:

[0041]

[0042] S4: Given the approximate diameter d1 of the circumscribed circle, the chamfer radius r, and the number of sides of the regular polygon, use CAD software to calculate the approximate cross-sectional area S′1 of the single wire;

[0043] S5: Since the approximate cross-sectional area of ​​the single wire S′1 is smaller than the approximate cross-sectional area of ​​the single wire S1, in order to maximize the approximate area of ​​S1 and considering that the dimensional processing accuracy of the drawing die in the diameter direction is controlled within 0.01 mm, the approximate diameter of the circumscribed circle is set to d2 = d1 + 0.01;

[0044] Given the approximate diameter d2 of the circumscribed circle, the chamfer radius r, and the number of sides of the regular polygon, use CAD software to calculate the approximate cross-sectional area S2 of the single wire;

[0045] S6: Select the value closest to the approximate area S1 from S′1 and S2 as the final monofilament cross-sectional area S, and the corresponding circumscribed circle diameter as the final circumscribed circle diameter d;

[0046] S7: Nomenclature: (L-circumscribed circle diameter-chamfer radius) (Ldr);

[0047] 2. Processing of regular polygonal monofilament

[0048] S1: According to the diameter d of the circumscribed circle of the regular polygon where the monofilament cross section is located, select an existing circular monofilament drawing die combination with a diameter close to d;

[0049] S2: For the dies in the monofilament drawing process, the last m dies are selectively replaced with corresponding special-shaped dies as needed, where m is a natural number and m≥1;

[0050] S3: passing the polygonal monofilaments through the die in sequence;

[0051] S4: Adjust the annealing coefficient according to Q=k1·Q0, where Q is the annealing coefficient of the polygonal monofilament, Q0 is the annealing coefficient of an existing circular monofilament with a diameter close to the circumscribed circle d, and k1 is the ratio of the cross-sectional perimeter of the circular monofilament to the cross-sectional perimeter of the polygonal monofilament to ensure product quality;

[0052] S5: Adjusting the production line speed according to V=K2·V0, where V is the polygonal monofilament production line speed, V0 is the existing circular monofilament production line speed close to the circumscribed circle diameter d, and K2 is the ratio of the polygonal monofilament cross-sectional area to the circular monofilament cross-sectional area;

[0053] S6: Adjust the wire width and set the wire length;

[0054] S7: draw the monofilament to check tensile strength, electrical resistance and outer diameter;

[0055] S8: make fine adjustments;

[0056] S9: Normal production.

[0057] Example 2

[0058] 1. Monofilament design

[0059] S1: Regular hexagonal monofilament cross section Figure 1 As shown, the approximate area S1 = 9.22 mm 2 ;

[0060] S2: According to Table 1, the chamfer radius r = 0.3 mm;

[0061] S3: Using the polygon formula (regular hexagon), we can get the circumscribed circle diameter d1 = 3.77 mm:

[0062]

[0063] S4: Given the approximate diameter d1 of the circumscribed circle, the chamfer radius r, and the number of sides of the regular polygon, use CAD software to calculate the approximate cross-sectional area of ​​the single wire S′1 = 9.20 mm 2 ;

[0064] S5: Since the approximate cross-sectional area of ​​the single wire S′1 is smaller than the approximate cross-sectional area of ​​the single wire S1, in order to maximize the approximate cross-sectional area of ​​S1, the dimensional processing accuracy of the drawing die in the diameter direction is controlled within 0.01 mm, and the approximate diameter of the circumscribed circle is set to d2 = d1 + 0.01 = 3.78 mm;

[0065] Given the approximate diameter d2 of the circumscribed circle, the chamfer radius r, and the number of sides of the regular polygon, use CAD software to calculate the approximate cross-sectional area of ​​the single wire S2 = 9.25 mm 2 ;

[0066] S6: Select the value closest to the approximate area S1 among S′1 and S2 as the final single-filament cross-sectional area S = 9.20 mm 2 , the corresponding circumscribed circle diameter is taken as the final circumscribed circle diameter d = 3.77 mm;

[0067] S7: Nomenclature: L-3.77-0.3.

[0068] 2. Monofilament processing

[0069] S1: Select a circular monofilament drawing die assembly with a diameter of 3.80 mm;

[0070] S2: Replace the last mold (exit mold) with a special-shaped mold;

[0071] S3: passing the polygonal monofilaments through the die in sequence;

[0072] S4: Select the annealing scheme for round monofilament with a diameter of 3.80 mm;

[0073] Adjust the annealing coefficient according to Q = k1·Q0, where Q is the annealing coefficient of the polygonal monofilament, Q0 is the annealing coefficient of the circular monofilament with similar diameter, and k1 is the ratio of the cross-sectional perimeter of the circular monofilament to the cross-sectional perimeter of the polygonal monofilament;

[0074] That is: k1 = circular monofilament cross-section perimeter / regular polygonal monofilament cross-section perimeter = 23.876 / 22.426 = 1.0647;

[0075] S5: Adjust the production line speed according to V=K2·V0, where V is the production line speed of the polygonal monofilament, V0 is the production line speed of the circular monofilament with similar diameter, and K2 is the ratio of the cross-sectional area of ​​the polygonal monofilament to the cross-sectional area of ​​the circular monofilament;

[0076] That is: K2 = regular polygonal monofilament cross-section / circular monofilament cross-section area = 9.22 / 11.16 = 0.83, adjust the production line speed V = K*V0 to ensure product quality;

[0077] S6: Adjust the wire width and set the wire length;

[0078] S7: draw the monofilament to check tensile strength, electrical resistance and outer diameter;

[0079] S8: make fine adjustments;

[0080] S9: Normal production.

Claims

1. A method for preparing polygonal monofilaments of submarine cables, characterized by: The following steps are involved: (1) Monofilament design ① Determine the approximate area S1 of the single-filament cross section based on the performance parameters of the cable; ② The cross section of the monofilament is a regular polygonal structure, and the chamfer radius r of the regular polygon is determined according to the approximate cross section area S1 of the monofilament; ③ Determine the diameter d of the circumscribed circle of the regular polygon where the monofilament cross section is located; (2) Monofilament processing ① According to the diameter d of the circumscribed circle of the regular polygon where the monofilament cross section is located, select a circular monofilament drawing die combination with a diameter close to the circumscribed circle d; ② For the dies in the last m passes of the monofilament drawing process, replace them with corresponding regular polygonal monofilament drawing dies; where m is a natural number and m ≥ 1; ③Draw the single wire. During the drawing process, adjust the annealing coefficient of the wire drawing machine and the production line speed according to the structure of the single wire.

2. The method for preparing a polygonal monofilament of a submarine cable according to claim 1, characterized in that: In step (1), the approximate area S1 of the cross section of the single wire is determined according to the resistance value of the cable, the number of single wires in the cable, and the material of the single wire.

3. The method for preparing a polygonal monofilament of a submarine cable according to claim 2, characterized in that: In step (1), the chamfer radius r of the regular polygon is determined according to Table 1: Table 1 Relationship between the approximate cross-sectional area of ​​regular polygonal monofilament and chamfer 4. The method for preparing a polygonal monofilament of a submarine cable according to claim 3, wherein: In step (1), determining the circumscribed circle diameter d of the regular polygon in which the monofilament cross section is located comprises the following steps: A. Given the approximate cross-sectional area S1 of a single wire and the number of sides of a regular polygon n, calculate the approximate diameter d1 of the circumscribed circle using the following regular polygon area formula: B. Given the approximate diameter d1 of the circumscribed circle, the chamfer radius r, and the number of sides of the regular polygon, use CAD software to calculate the approximate cross-sectional area S′1 of the single wire; C. Since the approximate cross-sectional area of ​​the single wire S′1 is smaller than the approximate cross-sectional area of ​​the single wire S1, in order to maximize the approximate area close to S1, and considering that the dimensional processing accuracy of the drawing die in the diameter direction is controlled within 0.01 mm, the approximate diameter of the circumscribed circle is set to d2 = d1 + 0.01; Given the approximate diameter d2 of the circumscribed circle, the chamfer radius r, and the number of sides of the regular polygon, use CAD software to calculate the approximate cross-sectional area S2 of the single wire; D. Select the value closest to the approximate area S1 from S′1 and S2 as the final single-filament cross-sectional area S, and the corresponding circumscribed circle diameter as the final circumscribed circle diameter d.

5. The method for preparing a polygonal monofilament of a submarine cable according to claim 1 or 4, characterized in that: In step (2), the annealing coefficient is adjusted according to Q=k1·Q0, where Q is the annealing coefficient of the polygonal monofilament, Q0 is the annealing coefficient of the circular monofilament close to the diameter d of the circumscribed circle, and k1 is the ratio of the circumference of the circular monofilament section to the circumference of the polygonal monofilament section.

6. The method for preparing a polygonal monofilament of a submarine cable according to claim 5, characterized in that: In step (2), the production line speed is adjusted according to V=K2·V0, where V is the polygonal monofilament production line speed, V0 is the circular monofilament production line speed close to the circumscribed circle diameter d, and K2 is the ratio of the polygonal monofilament cross-sectional area to the circular monofilament cross-sectional area.

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