Conductor bonding method and system

Abstract

The application discloses a conductor welding method and system, and the method comprises the following steps: fixing a first conductor and a second conductor on a stress applicator respectively, and applying reverse tension to the first conductor and the second conductor; placing the welding end portions of the first conductor and the second conductor after tensioning in a sealed fusion chamber, heating and welding the welding portions by a heater to form a third conductor, and meanwhile, maintaining a sealed environment by the sealed fusion chamber; and after welding, performing overall heating and tempering treatment on the third conductor by a heating and tempering device. Through the systematic process combination of pre-welding pretreatment, in-welding temperature control forming and post-welding overall stress relieving, the welding efficiency and joint quality of the large-section conductor are significantly improved, the residual stress is effectively reduced, and the long-term operation reliability of the joint under the deep-sea high water pressure and dynamic bending working condition is enhanced.

Description

Technical Field

[0001] This application relates to the technical field of high-end equipment manufacturing, and in particular to a conductor welding method and system. Background Technology

[0002] Currently, submarine cables serve as a crucial node in deep-sea energy transmission, and the reliability of their flexible joints directly impacts the feasibility of deep-sea energy development. Furthermore, with the rapid development of deep-sea exploration and the future energy internet, higher demands are being placed on the transmission capacity and service life of submarine cables.

[0003] However, existing welding methods generally suffer from problems such as low welding efficiency, high residual stress, and poor joint reliability, making it difficult to meet the long-term operation requirements of large cross-section conductors under high water pressure and dynamic bending environments. Summary of the Invention

[0004] This application provides a conductor welding method and system to solve the technical problems of existing welding methods, such as low welding efficiency, high residual stress, poor joint reliability, and difficulty in meeting the long-term operation requirements of large cross-section conductors under high water pressure and dynamic bending environments.

[0005] The first aspect of this application discloses a conductor welding method, the method comprising: The first conductor and the second conductor are fixed to the stress applicator respectively, and reverse tension is applied to the first conductor and the second conductor; The stretched first and second conductors are placed in a sealed welding chamber, and the welding parts are heated and welded by a heater to form a third conductor, while the sealed welding chamber maintains a sealed environment. After welding, the third conductor is subjected to overall heating and tempering treatment using a heating and tempering device.

[0006] In some embodiments, the weld ends of the stretched first and second conductors are placed in a sealed welding chamber, and the weld area is heated and welded by a heater, including: The first conductor is peeled off layer by layer from the outside to the inside to form multiple first monofilaments; The second conductor is peeled off layer by layer from the outside in to form multiple second monofilaments; The welding ends of the first and second monofilaments of the corresponding layer are joined together and placed in a sealed welding chamber. The monofilaments of each layer are welded sequentially from the inside out.

[0007] In some embodiments, when welding the first and second monofilaments of any layer, a sealing welding chamber is fitted over the outside of the welding ends of the first and second monofilaments of the current layer, nitrogen gas is introduced into the sealing welding chamber, and the monofilaments of the current layer are electromagnetically heated by a heater.

[0008] In some embodiments, a heat-absorbing liner is provided inside the sealed welding chamber. During the welding process, the heat-absorbing liner presses the welding ends radially and absorbs the residual heat of welding, so that the welding ends of the first and second monofilaments are formed in one go.

[0009] A second aspect of this application provides a conductor welding system, the system comprising: A stress applicator is used to apply reverse tension to the first and second conductors prior to welding. The sealed welding chamber receives the third conductor after it has been stretched by the stress applicator and provides a sealed and compacted welding environment for the welding ends of the first and second conductors. A heater, located outside the sealed welding chamber, is used to heat and weld the welding parts; and, A heating and tempering device is used to heat and temper the third conductor after welding.

[0010] In some embodiments, the stress applicator includes: Two fixed platforms, each fixed platform including a lower platform and an upper platform that can move horizontally relative to the lower platform; Multiple latches, at least one latch is provided on the upper platform of each fixed platform, for fixing the first conductor and the second conductor; A centering clamping device is located between two fixed platforms and is used to clamp the welding ends of the first conductor and the welding ends of the second conductor. And a traction control device, which is used to drive the upper platform of the two fixed platforms to move in opposite directions to apply a preset tension.

[0011] In some embodiments, the fixed platform includes a fixed lower platform and an upper platform that is horizontally movable via gear meshing.

[0012] In some embodiments, the sealed welding chamber includes: The thermal expansion chamber includes two openable rigid shell halves, with a heat-absorbing liner inside the rigid shell that has an expansion function. A nitrogen circulation device, connected to a thermal expansion chamber, for filling the thermal expansion chamber with nitrogen; and, A temperature sensor, mounted on a rigid housing, is used to monitor the nitrogen temperature inside the thermal expansion chamber in real time.

[0013] In some embodiments, the sealed welding chamber further includes a metal welding powder supply device, which is located inside or around the thermal expansion chamber and is used to spread the metal welding powder on the bonding point of the first monofilament and the second monofilament during welding.

[0014] In some embodiments, the heater is a Haver-type electromagnetic heater, located outside the sealed welding chamber, and employs a multi-layer spiral coil structure for electromagnetic induction heating of the welding area.

[0015] In some embodiments, the heating and tempering device is a through-core transformer assembly, including an iron core and a coil wound on the iron core, the iron core having a window through which the welded conductor passes for tempering the welded conductor.

[0016] The conductor welding method and system provided in this application include: fixing a first conductor and a second conductor to a stress applicator and applying reverse tension to the first and second conductors; placing the welded ends of the stretched first and second conductors in a sealed welding chamber, and heating and welding the welded parts to form a third conductor using a heater, while maintaining a sealed environment through the sealed welding chamber; after welding, performing overall heating and tempering treatment on the third conductor using a heating and tempering device. This application, through a systematic combination of pre-welding pretreatment, temperature-controlled forming during welding, and overall stress relief after welding, significantly improves the welding efficiency and joint quality of large-section conductors, effectively reduces residual stress, and enhances the long-term operational reliability of the joint under deep-sea high water pressure and dynamic bending conditions. Attached Figure Description

[0017] Figure 1 This is a structural block diagram of the conductor welding system provided in the embodiments of this application.

[0018] Figure 2 This is a schematic diagram of the cross-sectional structure of the welding conductor provided in the embodiment of this application.

[0019] Figure 3 This is a schematic diagram of the stress applicator provided in the embodiments of this application.

[0020] Figure 4 This is a schematic diagram of the sealed welding chamber provided in this embodiment.

[0021] Figure 5 This is a structural block diagram of the sealed welding chamber provided in this embodiment.

[0022] Figure 6 This is a structural block diagram of the thermal expansion chamber provided in this embodiment.

[0023] Figure 7 This is a structural block diagram of the heating and tempering device provided in the embodiments of this application.

[0024] Figure 8 This is a schematic flowchart of the conductor welding method provided in the embodiments of this application.

[0025] Figure 9 yes Figure 8 A schematic diagram of the sub-process of step S20.

[0026] Explanation of main component symbols: Conductor welding system 1000, stress applicator 100, sealed welding chamber 200, heater 300, heating and tempering device 400, iron core 410, coil 420, first conductor 10, first layer monofilament 11, second layer monofilament 12, third layer monofilament 13, second conductor 20, fixed platform 110, locking buckle 120, centering clamping device 130, traction control device 140, traction motor 141, electrical control device 142, lower platform 111, upper platform 112, thermal expansion chamber 210, nitrogen circulation device 220, temperature sensor 230, rigid shell 211, heat-absorbing liner 212. Detailed Implementation

[0027] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0028] Currently, submarine cables, as a crucial node in deep-sea energy transmission, bear the core responsibility of stably transmitting deep-sea energy from offshore wind power, oil and gas platforms, and other sources to land. The reliability of their flexible joints directly impacts the feasibility of deep-sea energy development. If a flexible joint breaks or fails during operation, it will not only cause the entire transmission line to be interrupted but also incur high offshore maintenance costs and prolonged power outages. Furthermore, with the rapid development of deep-sea exploration and the future energy internet, deep-sea energy development is continuously extending to deeper waters and farther distances, placing higher demands on the transmission capacity and service life of submarine cables. Large-section conductors, due to their advantages such as high current carrying capacity and low loss, are gradually becoming the preferred solution for deep-sea cables, but their welding difficulty also increases significantly.

[0029] However, existing welding methods generally suffer from low welding efficiency, high residual stress, and poor joint reliability, making it difficult to meet the long-term operational requirements of large-section conductors under high water pressure and dynamic bending environments. Traditional welding processes easily generate heat accumulation and stress concentration during welding, leading to grain coarsening and decreased mechanical strength in the joint area, and increasing the risk of fatigue fracture during long-term operation. In addition, high-temperature welding may damage adjacent insulation layers, accelerate the aging of insulation materials, and further shorten the overall service life of submarine cables.

[0030] Therefore, this application provides a conductor welding method and system. The method includes: fixing a first conductor and a second conductor to a stress applicator, and applying reverse tension to the first conductor and the second conductor; placing the welded ends of the stretched conductors in a sealed welding chamber, heating and welding the welded parts using a heater, while maintaining a sealed environment through the sealed welding chamber; and performing overall heating and tempering treatment on the welded conductors using a heating and tempering device after welding. This application significantly improves the welding efficiency and joint quality of large-section conductors through a systematic process combination of pre-welding pretreatment, temperature-controlled forming during welding, and overall stress relief after welding, effectively reducing residual stress and enhancing the long-term operational reliability of the joint under deep-sea high water pressure and dynamic bending conditions.

[0031] refer to Figure 1 This embodiment provides a conductor welding system 1000. The conductor welding system 1000 includes a stress applicator 100, a sealed welding chamber 200, a heater 300, and a heating and tempering device 400.

[0032] In some embodiments, the stress applicator 100 is used to apply a reverse tensile prestress F to the first conductor 10 and the second conductor 20 before welding. The reverse tensile prestress refers to the application of a tensile force axially to the first conductor 10 and the second conductor 20 by the stress applicator 100 before the shrinkage tensile stress generated by the welding heating-cooling cycle, thereby causing a predetermined amount of plastic elongation at the opposing welding ends of the first conductor 10 and the second conductor 20. During the cooling and shrinkage of the welded joint, this predetermined amount of plastic elongation can partially offset the residual tensile stress caused by the welding heat shrinkage, thereby reducing the final residual stress level of the joint.

[0033] The following description uses the example of the stress applicator 100 causing the first conductor 10 and the second conductor 20 to have a plastic elongation of 3-5 mm, but it is not limited to this. The plastic elongation of the first conductor 10 and the second conductor 20 can be determined according to the outer diameter of the first conductor 10 and the second conductor 20.

[0034] In some embodiments, the reverse tensile prestress F applied by the stress applicator 100 can range from 30 to 50 N / mm², and the stretching speed of the stress applicator 100 is typically controlled at 1 mm / min, causing the clamping-welding section of the first conductor 10 and the second conductor 20 to extend by 3 to 5 mm, with a total stretching time not exceeding 6 min. After reaching the tensile prestress, the stretching of the first conductor 10 and the second conductor 20 is maintained to complete the pre-stretching treatment of the welding ends; subsequently, the stress applicator 100 can be reset or the pre-stretching load can be released before proceeding with subsequent welding steps. For example, when both the first conductor 10 and the second conductor 20 are compacted copper stranded conductors with a cross-section of 800 mm², the reverse tensile prestress can be set to 40 N / mm², requiring a tensile force of approximately 32,000 N. The conductor ends are stretched by approximately 4 mm from their original length, held for 5 min, and then welded. This pre-stretching amount has been verified by tests to offset about 30% to 40% of the welding shrinkage stress after welding. After tempering at 500 to 600°C, the final welding residual stress elimination rate reaches 80% to 90%.

[0035] refer to Figure 2 In some embodiments, the first conductor 10 and the second conductor 20 may be made of metal. For example, the first conductor 10 and the second conductor 20 may be stranded conductors made of conductive materials such as copper, aluminum, or aluminum alloys, which are commonly used in submarine cables, large-section power cables, and other fields. The first conductor 10 and the second conductor 20 each have a multi-layer stranded monofilament structure extending axially. For example, the first conductor 10 may include a first layer monofilament 11, a second layer monofilament 12, and a third layer monofilament 13, and their welded ends need to be connected as a single unit by welding to form a continuous conductive path.

[0036] refer to Figure 3 The stress applicator 100 includes two fixed platforms 110, multiple latches 120, a centering clamping device 130, and a traction control device 140.

[0037] In some embodiments, the fixed platform 110 includes a lower platform 111 and an upper platform 112 that is horizontally movable relative to the lower platform 111. The lower platform 111 serves as the base of the entire stress applicator 100 and is fixedly mounted on a workbench or support frame, providing a stable support foundation for the movement of the upper platform 112. The upper platform 112 is stacked on top of the lower platform 111 and is connected to a traction control device 140. The traction control device 140 drives the upper platform 112 to reciprocate in the horizontal direction, i.e., the axial direction of the first conductor 10 and the second conductor 20.

[0038] In one embodiment, there are two traction control devices 140, located on either side of the centering clamping device 130. There are also two upper platforms 112. Each upper platform 112 is located between one traction control device 140 and the centering clamping device 130. A first conductor 10 is connected between one upper platform 112 and the centering clamping device 130 via a latch 120, and a second conductor 20 is connected between the other upper platform 112 and the centering clamping device 130 via a latch 120. One of the two traction control devices 140 drives the corresponding upper platform 112 to move, thereby stretching the first conductor 10 relative to the centering clamping device 130.

[0039] In some embodiments, to achieve precise horizontal movement of the upper platform 112, the fixed platform 110 may employ a gear transmission structure. For example, a meshing gear transmission mechanism is provided between the lower platform 111 and the upper platform 112. The traction control device 140 drives the gears to rotate, and through gear meshing transmission, the upper platform 112 moves smoothly relative to the lower platform 111 in a preset direction. The double-layer gear meshing structure has advantages such as high transmission accuracy, strong load-bearing capacity, and smooth movement, ensuring precise control of the tension of the conductors (first conductor 10, second conductor 20) during the application of reverse tensile prestress.

[0040] In some embodiments, at least two latches 120 secure a conductor, each latch 120 being disposed on the upper platform 112. For example, four latches 120 connected to the upper platform 112 are used to secure the first conductor 10 and the second conductor 20, respectively. The upper platform 112 can be structurally divided into a first fixing part and a second fixing part, wherein the first fixing part is equipped with two latches 120 spaced apart along the conductor axial direction for clamping and locking the first conductor 10; the second fixing part is also equipped with two latches 120 spaced apart along the conductor axial direction for clamping and locking the second conductor 20. In one embodiment, the latches 120 may employ a reverse stress engagement structure, with high-strength PE engagement strips padded at the engagement points to prevent damage to the conductor surface during stretching.

[0041] In some embodiments, the centering clamping device 130 may be disposed in the middle of the fixed platform 110 for clamping the welding ends of the first conductor 10 and the second conductor 20 and ensuring that the axes of the two conductors are aligned. The centering clamping device 130 may adopt a Haver-type structure, including two openable clamping blocks. One side of the two clamping blocks is rotatably connected by a pin or hinge to form an openable pivot shaft, and the other side is provided with a detachable locking element, such as a bolt, nut, or quick-release buckle. When it is necessary to insert or remove the conductors, the locking element is released to allow the two clamping blocks to open relative to each other around the pivot shaft, so as to laterally insert and clamp the welding ends of the first conductor 10 and the second conductor 20. After closing, the locking element fixes the two clamping blocks so that the positioning grooves on the inner circumference of the two clamping blocks grip the outer circle of the conductors.

[0042] In some embodiments, the traction control device 140 is connected to the upper platform 112 for driving the upper platform 112 to move in the horizontal direction, thereby applying a preset reverse tensile tension to the first conductor 10 and the second conductor 20 fixed on the latch 120.

[0043] In some embodiments, the traction control device 140 includes a traction motor 141 and an electronic control device 142. The traction motor 141 is drive-connected to the upper platform 112 and provides driving force; the electronic control device 142 is electrically connected to the traction motor 141 and controls the start, stop, forward and reverse rotation, and speed of the traction motor 141, thereby precisely controlling the moving speed and displacement of the upper platform 112 and achieving precise adjustment of the reverse tensile tension. The traction motor 141 may be a servo motor or a stepper motor, used to provide precisely controllable driving torque.

[0044] refer to Figure 4 and Figure 5 The sealed welding chamber 200 provides a sealed and tight-fitting welding environment. The sealed welding chamber 200 includes a thermally expandable chamber 210, a nitrogen circulation device 220, and a temperature sensor 230. The sealed welding chamber 200 is located above the stress applicator 100 and is movable to the welding butt joint position of the first conductor 10 and the second conductor 20 to provide a sealed welding environment during the welding process.

[0045] refer to Figure 6 In some embodiments, the thermally expandable chamber 210 includes two openable rigid shell halves 211, with an expansion-functional heat-absorbing liner 212 on the inner side of the rigid shell 211. The inner wall of the rigid shell 211 is tightly fitted to the heat-absorbing liner 212, providing rigid support for the heat-absorbing liner 212. During the welding process, when the heat-absorbing liner 212 expands due to heat, it can apply force evenly inward along the radial direction.

[0046] It is understood that the rigid shell 211 can be made of high-temperature resistant metal material, such as stainless steel, nickel-based high-temperature alloy or titanium alloy, which has good high-temperature resistance and structural strength; the heat-absorbing liner 212 is attached to the inner side of the rigid shell 211 and can be made of high-temperature soft tungsten metal body and high-temperature resistant rubber body. When heated, it can undergo thermal expansion, apply radial clamping force to the welded parts, and rebound and release after cooling.

[0047] It is understandable that the high-temperature soft tungsten metal body possesses characteristics such as rapid thermal conductivity, high temperature resistance, and slight deformation, enabling it to quickly absorb heat and undergo thermal expansion during welding heating. The high-temperature resistant rubber body provides elastic rebound capability, allowing the heat-absorbing liner 212 to spring back to its original position after cooling. During the welding process, the heat-absorbing liner 212 expands due to heat, applying a uniform compressive force radially inward to the welding area, causing the weld point to be formed into a rounded transition shape in one go. Simultaneously, the heat-absorbing liner 212 rapidly absorbs excess heat generated during welding and conducts it outward through the rigid shell 211, achieving rapid heat dissipation in conjunction with the forced convection of the nitrogen circulation device 220. After welding is completed, the heat-absorbing liner 212 springs back and releases as the temperature drops, releasing the compression on the welding area and facilitating the opening and removal of the welded conductor.

[0048] In some embodiments, the nitrogen circulation device 220 is internally connected to the thermal expansion chamber 210, and is used to fill the thermal expansion chamber 210 with constant-temperature nitrogen gas to maintain stable internal pressure and remove excess heat. The temperature range of the constant-temperature nitrogen gas is controlled between 0 and 2°C, for example, 1°C. This temperature is lower than the ambient temperature, allowing it to quickly absorb and remove excess heat conducted by the heat-absorbing liner 212 during the short welding process, such as 3-5 seconds, preventing heat diffusion to the conductor insulation side and avoiding pressure fluctuations caused by excessive gas expansion due to heat. The internal pressure range can be maintained between 0.05 and 0.15 MPa, such as 0.1 MPa. This range not only isolates oxygen through an inert atmosphere to reduce the risk of oxidation, but also allows the heat-absorbing liner 212 to obtain uniform back pressure support from the rigid shell 211 during thermal expansion, achieving radial constant pressure clamping of the weld.

[0049] In some embodiments, the nitrogen circulation device 220 may include a nitrogen storage tank, a pressure regulating valve, a flow meter, a refrigeration / heating temperature control unit, and a circulation pump. The nitrogen storage tank can provide high-purity nitrogen (purity ≥99.99%). After the pressure is reduced by the pressure regulating valve, the refrigeration / heating temperature control unit controls the nitrogen temperature within a set constant temperature range, and then sends it into the thermal expansion chamber 210 through a hose. The nitrogen discharged from the chamber returns to the circulation pump through the return pipe to form a closed or semi-open circulation, so as to maintain a slight positive pressure inside the chamber and continuously remove heat from the welding area.

[0050] In some embodiments, the outer wall of the rigid housing 211 is further provided with a temperature sensor 230 for real-time monitoring of the nitrogen temperature inside the thermal expansion chamber 210 and feeding the temperature signal back to the control system to adjust the nitrogen circulation volume. The temperature sensor 230 includes, but is not limited to, at least one of a thermocouple, a thermistor, a platinum resistance temperature sensor, an infrared temperature sensor, a semiconductor temperature sensor, a fiber optic temperature sensor, or an integrated circuit temperature sensor. Furthermore, the rigid housing 211 is also provided with a vent interface for connection to the nitrogen circulation device 220 to achieve constant-temperature nitrogen filling and circulation.

[0051] Understandably, during operation, the temperature sensor 230 monitors the nitrogen temperature in real time and feeds the signal back to the control unit of the nitrogen circulation device 220. When the temperature deviates from the set range, the flow rate of nitrogen input into the chamber through the air port of the nitrogen circulation device 220 is automatically adjusted to achieve constant temperature and pressure control. For example, when the temperature sensor 230 detects that the nitrogen temperature in the chamber is higher than the upper limit of the set temperature, such as 2°C, it determines that too much heat has accumulated in the chamber and automatically increases the nitrogen input flow rate of the nitrogen circulation device 220 and / or reduces the set temperature of the refrigeration temperature control unit to accelerate the replacement rate of the low-temperature nitrogen in the chamber, thereby quickly removing excess heat and causing the temperature in the chamber to drop back to the set range. Conversely, when the temperature sensor 230 detects that the nitrogen temperature in the chamber is lower than the lower limit of the set temperature, such as 0°C, it determines that the chamber is too cold and automatically reduces the nitrogen input flow rate or starts the heating temperature control unit to moderately heat the circulating nitrogen, causing the temperature in the chamber to rise back to the set range. Through this closed-loop feedback regulation mechanism, the nitrogen temperature inside the thermal expansion chamber 210 can always be maintained within the set constant temperature range, such as 0~2℃, ensuring that the thermal expansion behavior of the heat-absorbing lining 212 is stable and controllable during the welding process, while avoiding the adverse effects of drastic temperature fluctuations on welding quality and conductor insulation layer.

[0052] In some embodiments, the sealed welding chamber 200 further includes a metal welding powder supply device for distributing metal welding powder to the bonding points of the conductor monofilaments during welding. The metal welding powder may be composed of aluminum powder, magnesium powder, copper oxide, nickel oxide, nitrocellulose, and hydroxyl-terminated polybutadiene.

[0053] It can be understood that, by weight, the composition of the metal welding powder can be: 2 parts aluminum metal powder, 2 parts magnesium metal powder, 3 parts copper oxide, 3 parts nickel oxide, 0.5 parts nitrocellulose, and 0.5 parts hydroxyl-terminated polybutadiene. Among these, the aluminum and magnesium metal powders act as fuel components, releasing a large amount of heat through a redox reaction upon heating; copper oxide and nickel oxide act as oxidants, providing the oxygen element required for the reaction; and nitrocellulose and hydroxyl-terminated polybutadiene act as binders and combustion rate regulators, ensuring uniform combustion and heat release during welding heating. During the welding process, the aforementioned metal welding powder is sprinkled onto the bonding points of the conductor monofilaments. When the Haver-type electromagnetic heater 300 induction heats the welding area, the metal welding powder undergoes an exothermic reaction, releasing heat that assists in melting the end faces of the conductor monofilaments, promoting metallurgical bonding between the monofilaments, and further improving welding quality and efficiency.

[0054] In some embodiments, the heater 300 may be a Haver-type electromagnetic heater with a ring-shaped structure, fitted over the outside of the sealed welding chamber 200, for heating the welding area. The heater 300 may employ a multi-layer spiral coil structure, with the coil wound on an insulating frame or cooling jacket, and the two halves of the coil closed by a locking mechanism to form a complete ring. During operation, the heater 300 is connected to a high-frequency power supply. After being energized, an alternating magnetic field is generated inside the coil. This alternating magnetic field penetrates the rigid shell 211 and the heat-absorbing liner 212 of the sealed welding chamber 200, inducing eddy currents at the conductor welding area located at the center of the chamber. This induces Joule heating using the conductor's own resistance, achieving rapid localized heating. Due to the extremely short heating time, for example, 3-5 seconds, the heat-affected zone is small, effectively preventing heat damage to adjacent insulation layers.

[0055] In some embodiments, the inner diameter of the heater 300 is larger than the outer diameter of the sealed welding chamber 200, with a gap between them, for example, 5 to 10 mm, to avoid direct heat transfer and ensure convenient disassembly and assembly; this gap also allows the sealed welding chamber 200 to undergo slight radial displacement during welding due to the micro-expansion of the inner lining.

[0056] refer to Figure 7 In some embodiments, the heating and tempering device 400 may be a through-core transformer assembly, located on one side of the stress applicator 100, for performing overall heating and tempering treatment on the welded conductor after welding is completed.

[0057] In some embodiments, the heating and tempering device 400 includes an iron core 410 and a coil 420 wound on the iron core 410. The iron core 410 has a ring-shaped or rectangular frame structure with a window formed in the center for the welded conductor to pass through. The coil 420 is wound on one or more sides of the iron core 410 and connected to an AC power source. When the welded conductor passes through the window, AC power is applied through the coil 420, generating an alternating magnetic flux in the iron core 410, which in turn induces a large current in the conductor passing through the window. Due to the conductor's inherent resistance, the induced current generates Joule heat as it flows through the conductor, resulting in uniform heating of the entire conductor. By adjusting the magnitude and duration of the input current, the entire conductor can be heated to 500-600°C and held at that temperature for a certain time, such as 10 minutes, to achieve overall tempering and effectively eliminate residual stress generated during the welding process. Compared with traditional local heating methods, the feedthrough transformer assembly can heat the entire conductor uniformly, avoiding problems such as large temperature gradients and incomplete stress relief caused by local heating, and can achieve a residual stress relief rate of 80% to 90% for welded joints.

[0058] refer to Figure 8 , Figure 8 This is a schematic flowchart of the conductor welding method provided in an embodiment of this application. In some embodiments, such as Figure 8 As shown, the conductor welding method includes the following steps: Step S10: Fix the first conductor 10 and the second conductor 20 to the stress applicator 100 respectively, and apply reverse tension to the first conductor 10 and the second conductor 20.

[0059] It is understood that the ends of the first conductor 10 and the second conductor 20 are first placed on the upper platform 112 of the stress applicator 100, and the first conductor 10 and the second conductor 20 are pressed and fixed by the latches at both ends of the upper platform 112. The latch 120 adopts a reverse stress engagement structure and a high-strength PE engagement strip is padded at the engagement point to prevent damage to the conductor surface during the stretching process. At the same time, the centering clamping device 130 is clamped at the welding ends of the first conductor 10 and the second conductor 20 to ensure that the axes of the two conductors are aligned and at the same horizontal height. After the fixing and centering are completed, the traction control device 140 is activated to drive the upper platform 112 to move away from the centering clamping device 130, and apply reverse tensile prestress to the first conductor 10 and the second conductor 20. The value of the reverse tensile prestress can be 30~50 N / mm², and the tensile speed is controlled at 1 mm / min, so that the clamping-welding section of the first conductor 10 and the second conductor 20, originally 20~40 cm long, elongates by 3~5 mm, and the total tensile time does not exceed 6 min.

[0060] It should also be noted that after the reverse tensile prestress applied to the first conductor 10 and the second conductor 20 reaches the preset tension, the centering clamping device 130 is kept locked to complete the pre-stretching treatment of the welding ends, thus obtaining the pre-stretched first conductor 10 and the pre-stretched second conductor 20. The preset tension refers to the axial tensile force calculated based on the selected reverse tensile prestress, such as 30~50 N / mm², and the cross-sectional area of ​​the first conductor 10 and the second conductor 20. When the actual tensile force detected by the stress applicator 100 reaches this calculated value, it is determined that the preset tension has been reached.

[0061] Step S20: Place the welded ends of the stretched first conductor 10 and second conductor 20 into the sealed welding chamber 200, and heat and weld the welded parts to form a third conductor through the heater 300, while maintaining a sealed environment through the sealed welding chamber 200. It is understood that, firstly, the welding ends of the first conductor 10 and the second conductor 20, after pre-stretching treatment in step S10, are aligned and fitted together, ensuring that the center lines of the first conductor 10 and the second conductor 20 are on the same horizontal line and that the welding ends are in close contact; then, the thermal expansion chamber 210 of the sealed welding chamber 200 is opened and fitted laterally onto the outside of the welding end joint of the first conductor 10 and the second conductor 20, so that the welding joint is located at the center of the thermal expansion chamber 210; the thermal expansion chamber 210 is closed and locked with the latch 120 to form a sealed cavity, and the nitrogen circulation device 220 is activated, filling the thermal expansion chamber 210 with constant-temperature nitrogen through the hose, maintaining the pressure inside the chamber at 0.1MPa and the nitrogen temperature at 0~2℃. Nitrogen, as an inert gas, can effectively isolate oxygen and prevent oxidation of the welding area at high temperatures. Simultaneously, the low-temperature nitrogen can quickly remove excess heat during the welding process, protecting the adjacent insulation layer from heat damage. Finally, the heater 300, such as a Haver-type electromagnetic heater, is fitted onto the outside of the sealed welding chamber, and then the heater 300 is activated to electromagnetically induction heat the welding area.

[0062] It should be noted that the inner diameter of heater 300 is larger than the outer diameter of the sealed welding chamber 200, with a gap between them to avoid direct contact. Heater 300 employs a multi-layer spiral coil structure and is connected to a high-frequency power supply. When energized, it generates an alternating magnetic field, inducing eddy currents at the conductor welding area. This, in turn, utilizes the conductor's own resistance to generate Joule heating, achieving rapid localized heating. The welding time is typically controlled within 3-5 seconds, and the heating current can be set to 4000A.

[0063] It should also be noted that during the welding process, the heat-absorbing lining 212 inside the thermal expansion chamber 210 expands due to heat, applying a uniform clamping force radially inward to the welding area, thus shaping the weld point into a rounded transition shape in one go. Simultaneously, the heat-absorbing lining 212 rapidly absorbs excess heat generated during welding and conducts it outward through the rigid shell 211, achieving rapid heat dissipation in conjunction with the forced convection of the nitrogen circulation device 220. After completing the welding of the current layer, the heater 300 and the sealed welding chamber 200 are removed sequentially to prepare for welding the next layer of monofilaments.

[0064] refer to Figure 9 , Figure 9 yes Figure 8 A schematic diagram of the sub-process of step S20. In some embodiments, the welding area may be heated and welded based on steps S21 to S23.

[0065] Step S21: The first conductor 10 is peeled off layer by layer from the outside to the inside to form a plurality of first monofilaments.

[0066] In some embodiments, the ends of the first conductor 10 and the second conductor 20 are peeled off layer by layer to expose multiple layers of monofilaments. The process of peeling the first conductor 10 layer by layer from the outside to the inside to form multiple first monofilaments includes, but is not limited to, measuring a length of 10-15 cm as a pre-welding section at the end of the first conductor 10 during the layer peeling process, and securing it with copper wire near the locking side of the stress applicator 100 to prevent the conductor from loosening; then, peeling off the monofilaments starting from the outermost layer: during the peeling process, the monofilaments are strictly controlled to naturally spread out along their original stranding pitch direction, rather than being forcibly bent at right angles, to avoid damaging the metal lattice structure on the surface of the monofilaments or causing dead bends. After removing the outermost layer of monofilaments, the remaining stranded layer monofilaments are peeled off layer by layer inward in the same way until the required welding layer is exposed. This "opening from the outside in, along the pitch" operation method can maintain the original mechanical properties and stranding tension of the monofilament to the maximum extent, ensuring that the shrinkage deformation of each layer of monofilament is coordinated and consistent during subsequent welding and overall tempering, and avoiding the introduction of additional stress due to improper pretreatment.

[0067] Step S22: The second conductor 20 is peeled off layer by layer from the outside to the inside to form multiple second monofilaments.

[0068] In some embodiments, the process of peeling the second conductor 20 layer by layer from the outside in to form multiple second monofilaments includes, but is not limited to, leaving a 10-15 cm pre-treated section at the end of the second conductor 20 and securing it with copper wire near the locking side of the stress applicator 100 to prevent the outer monofilaments from loosening. Subsequently, the outer monofilaments of the second conductor 20 are peeled off layer by layer from the outside in until the desired welding layer is exposed. When peeling off each layer of monofilaments, the peeling direction is strictly controlled to follow the original twisting pitch of the monofilaments, allowing the monofilaments to naturally disperse in a spiral shape. Forced right-angle bending is strictly prohibited to avoid damaging the metal lattice on the surface of the monofilaments or causing dead bends. After peeling, the end of the second conductor 20 forms a stepped exposed structure composed of multiple second monofilaments. This structure allows the ends of each layer of second monofilaments to be precisely connected with the first monofilament of the corresponding layer, and the stepped transition helps to reduce the abrupt change in cross-section at the welding joint, reducing electric field concentration and stress concentration.

[0069] Furthermore, when welding the first and second monofilaments of any layer, the sealing welding chamber 200 is fitted outside the welding ends of the first and second monofilaments of the current layer, nitrogen gas is filled into the sealing welding chamber 200, and the monofilaments of the current layer are electromagnetically heated by the heater 300.

[0070] In some embodiments, when welding any layer of monofilaments, the sealing welding chamber 200 is first fitted outside the joint of the current layer of monofilaments, ensuring that the joint is located in the central area of ​​the sealing welding chamber 200. Then, constant-temperature nitrogen gas, pre-cooled to 0-2°C, is introduced into the chamber through the gas circulation port, and the pressure inside the chamber is stably maintained at 0.1 MPa. This low-temperature, low-pressure inert environment prevents oxidation and burning of the monofilament surface at high welding temperatures, ensuring excellent metallurgical bonding quality. Furthermore, utilizing the excellent thermal conductivity of nitrogen gas, combined with the heat-absorbing lining 212 on the inner wall of the sealing welding chamber 200, it can rapidly absorb and remove the large amount of residual heat generated during welding, achieving millisecond-level rapid cooling. Simultaneously, a heater 300 is fitted outside the sealing welding chamber 200, and a high current of 4000A is applied for electromagnetic induction heating. A safe gap of 5-10 mm is maintained between the inner wall of the heater 300 and the outer wall of the welding chamber 200.

[0071] Step S23: Connect the welding ends of the first and second monofilaments of the corresponding layer and place them in the sealed welding chamber 200. Weld the monofilaments of each layer from the inside out.

[0072] It is understood that after the end-to-end peeling of the first conductor 10 and the second conductor 20 is completed, the welding ends of the first and second monofilaments of the corresponding layers are first coaxially butted together to ensure that they are tightly abutted in the axial direction and the contact surfaces are flat. After the butt joint is completed, the butt joint is placed in the central area of ​​the breathing constant temperature sealed welding chamber 200 for welding. The welding process follows the principle of progressing from the inside out and layer by layer, which includes, but is not limited to, first welding the central monofilament of the innermost layer to establish the reference axis of the joint; then, the sealed welding chamber 200 is successively fitted onto the outside of the butt joint of the next layer of monofilaments, and the processes of filling with constant temperature nitrogen, electromagnetic heating and radial compression are repeated until the outermost monofilament is welded. This layer-by-layer welding sequence from the inside out can effectively avoid the restraining effect of the welded layer on the unwelded layer. Combined with the real-time heat absorption and radial compression of the sealed welding chamber 200 during each layer welding, it ensures that the monofilaments of each layer complete the metallurgical bonding in a free state, thereby ensuring the radial uniformity and geometric roundness of the entire welded joint and preventing interlayer misalignment or eccentricity caused by welding thermal stress. Furthermore, the sealed welding chamber 200 is provided with a heat-absorbing liner 212. During the welding process, the heat-absorbing liner 212 presses the welding ends radially and absorbs the residual heat of welding, so that the welding ends of the first and second monofilaments are formed in one go.

[0073] Understandably, under the action of an electromagnetic field, the single-wire joint instantaneously generates a skin effect and rapidly heats up and melts. Meanwhile, the heat-absorbing lining 212 of the sealed welding chamber 200, under the action of constant temperature nitrogen pressure, can apply a continuous radial clamping force to the molten welding point, forcing the molten metal to be rounded and formed in a confined space in one go, effectively avoiding the generation of defects such as weld beads and porosity, and ensuring the smoothness and density of the weld surface.

[0074] Step S30: After welding is completed, the third conductor is subjected to overall heating and tempering treatment by the heating and tempering device 400.

[0075] It is understood that after all layers of monofilament welding of the first conductor 10 and the second conductor 20 are completed and the locking buckles 120 of the sealing welding chamber 200 and the stress applicator 100 are removed, the welded integrated conductor must first be horizontally passed through the core window of the heating and tempering device 400, such as a through-core transformer assembly, so that the weld and the conductor of sufficient length on both sides are placed within the magnetic circuit range of the core; then the heating and tempering device 400 is started, and alternating current is passed through the coil 420 to generate alternating magnetic flux in the core, thereby inducing a large current in the conductor, and then using the resistance of the conductor itself to generate Joule heat, uniformly heating the entire conductor, including the weld area and the heat-affected zone of the entire conductor, to 500~600℃, and holding at this temperature for 10 minutes, so that the residual stress of the weld joint and the adjacent area can be eliminated through stress relaxation and recrystallization process; after the holding is completed, the power supply of the heating and tempering device is cut off, and the conductor is allowed to cool naturally to room temperature with the environment. After overall tempering, the residual stress relief rate of the welded joint can reach 80%~90%, and the mechanical strength, bending performance and long-term operational reliability of the joint are close to the level of the conductor body, meeting the requirements for use of submarine cable flexible joints under deep water and dynamic bending conditions.

[0076] Furthermore, the heating and tempering device 400 is a through-core transformer. After welding is completed, the welded conductor is subjected to overall heating and tempering treatment by the heating and tempering device 400, including: after all layers of single wires are welded, the welded conductor is placed in the center of the magnetic circuit of the through-core transformer, and the welded conductor is heated to 500~600℃ by the through-core transformer and then kept warm and cooled.

[0077] It is understandable that after all layers of single-wire welding are completed, the clamping mechanism of the stress applicator 100 and the external sealed welding chamber 200 are removed, and the welded conductor is placed at the center of the magnetic circuit of the through-core transformer. The through-core transformer is started, and the Joule heat generated by the large current passing through the conductor body and the induction heating effect of the alternating magnetic field are used to uniformly heat the entire conductor to the target temperature range of 500~600℃. This temperature is maintained for 10 minutes, utilizing the high-temperature recovery and recrystallization mechanism of metals to repair the lattice distortion caused by localized heating and mechanical deformation during welding, and to fully release the residual tensile stress inside the weld joint. Compared to the limitation of traditional localized flame heating or induction heating, which can only eliminate 60%~80% of residual stress, the overall heating and tempering process using the through-core transformer can achieve a stress elimination rate of 80%~90%. After the insulation is completed, the current is cut off, allowing the conductor to cool naturally and slowly to room temperature, thereby obtaining a high-quality flexible joint with uniform structure and extremely low internal stress, ensuring that it can meet the long-term reliable operation requirements of submarine cables in harsh environments such as deep-sea high water pressure and dynamic bending.

[0078] It should be understood that the above are merely illustrative examples and do not constitute any limitation on the technical solution of this application. In specific applications, those skilled in the art can make settings as needed, and this application does not impose any restrictions on this.

[0079] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of this application. In practical applications, those skilled in the art can select some or all of it to achieve the purpose of this embodiment according to actual needs, and no restrictions are imposed here.

[0080] In addition, for technical details not described in detail in this embodiment, please refer to the conductor welding method and system provided in any embodiment of this application, which will not be repeated here.

[0081] Furthermore, it should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0082] The sequence numbers of the embodiments in this application are for description only and do not represent the superiority or inferiority of the embodiments.

[0083] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A conductor welding method, characterized in that, include: The first conductor and the second conductor are respectively fixed to the stress applicator, and reverse tension is applied to the first conductor and the second conductor; The stretched first conductor and the welding ends of the second conductor are placed in a sealed welding chamber. The welding parts are heated and welded by a heater to form a third conductor. At the same time, the sealed welding chamber maintains a sealed environment. After welding, the third conductor is subjected to overall heating and tempering treatment using a heating and tempering device.

2. The conductor welding method according to claim 1, characterized in that, The step of placing the stretched ends of the first and second conductors into a sealed welding chamber and heating the welding area with a heater includes: The first conductor is peeled off layer by layer from the outside to the inside to form multiple first monofilaments; The second conductor is peeled off layer by layer from the outside to the inside to form multiple second monofilaments; The welding ends of the first and second monofilaments of the corresponding layers are joined together and placed in the sealed welding chamber. The monofilaments of each layer are welded sequentially from the inside out.

3. The conductor welding method according to claim 2, characterized in that, When welding the first and second monofilaments of any layer, the sealing welding chamber is fitted outside the welding ends of the first and second monofilaments of the current layer, nitrogen gas is filled into the sealing welding chamber, and the monofilaments of the current layer are electromagnetically heated by the heater.

4. The conductor welding method according to claim 2, characterized in that, The sealed welding chamber is equipped with a heat-absorbing liner. During the welding process, the heat-absorbing liner presses the welding ends radially and absorbs the residual heat of welding, so that the welding ends of the first monofilament and the second monofilament are formed in one go.

5. A conductor welding system, applicable to the conductor welding method according to any one of claims 1 to 4, characterized in that, The system includes: A stress applicator is used to apply reverse tension to the first conductor and the second conductor prior to welding; The sealed welding chamber receives the third conductor after it has been stretched by the stress applicator and provides a sealed welding environment for the welding ends of the first and second conductors; A heater, located outside the sealed welding chamber, is used for heating and welding the welded parts; and, A heating and tempering device is used to heat and temper the welded third conductor after welding is completed.

6. The conductor welding system according to claim 5, characterized in that, The stress applicator includes: Two fixed platforms, each of the fixed platforms including a lower platform and an upper platform that can move horizontally relative to the lower platform; Multiple latches, at least one of the latches being disposed on the upper platform of each of the fixed platforms, for securing the first conductor and the second conductor; A centering clamping device is disposed between the two fixed platforms and is used to clamp the welding ends of the first conductor and the welding ends of the second conductor. And a traction control device for driving the upper platform of the two fixed platforms to move in opposite directions to apply a preset tension.

7. The conductor welding system according to claim 5, characterized in that, The sealed welding chamber includes: The thermal expansion chamber includes two openable rigid shell halves, and the inner side of the rigid shell is provided with a heat-absorbing liner with expansion function. A nitrogen circulation device, connected to the thermal expansion chamber, for filling the thermal expansion chamber with nitrogen; and, A temperature sensor, which is mounted on the rigid housing, is used to monitor the nitrogen temperature inside the thermal expansion chamber in real time.

8. The conductor welding system according to claim 7, characterized in that, The sealed welding chamber also includes a metal welding powder supply device, which is located inside or around the thermal expansion chamber and is used to spread the metal welding powder on the bonding point of the first monofilament and the second monofilament during welding.

9. The conductor welding system according to claim 5, characterized in that, The heater is a Haver-type electromagnetic heater, located outside the sealed welding chamber, and employs a multi-layer spiral coil structure for electromagnetic induction heating of the welding area.

10. The conductor welding system according to claim 5, characterized in that, The heating and tempering device is a through-core transformer assembly, including an iron core and a coil wound on the iron core. The iron core has a window through which the welded conductor passes for tempering the welded conductor.

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