Submarine cable connection method

Abstract

The invention relates to the technical field of cable production, and provides a submarine cable connection method, which comprises the following steps: firstly stripping non-conductor layers at the ends of a first cable and a second cable, stripping a second conductor with a larger diameter layer by layer from outside to inside, and measuring the section diameter of each layer of monofilament; screening out a target layer, wherein the difference value between the target layer and the first conductor with the smaller diameter is within a target value, respectively exposing central wires of the two conductors, and completing connection; and grouping, centering and welding the monofilaments in the target layer of the second conductor and the monofilaments in the corresponding layer of the first conductor layer by layer, rotating and twisting the welded monofilament layer, performing spot welding and reinforcing, and finally coating and welding the target layer of the second conductor and the monofilaments on the outer side to the outer side of the end of the first conductor layer by layer. Through precise hierarchical matching, refined welding and smooth transition coating, the regularity and mechanical strength of the joint structure are improved, stress and electrical hidden dangers caused by sudden change of the outer diameter are eliminated, and the operation stability of the unequal-diameter submarine cable connection joint is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable production, and particularly relates to a submarine cable splicing method. BACKGROUND

[0002] With the rapid development of deep-sea energy projects such as offshore wind power and cross-sea networking, submarine cables with large length and large transmission capacity are increasingly widely used. Due to the limitations of production, transportation and laying conditions, submarine cable splicing has become a necessary link to realize long-distance submarine cable laying, and the quality of conductor splicing directly determines the electrical properties, mechanical strength and operational reliability of the submarine cable.

[0003] Current submarine cable conductor splicing processes are mostly designed for equal-diameter and same-specification conductors. For unequal-section submarine cable conductors with different diameters, the traditional splicing method usually directly butt-welds the end heads of the two types of conductors as a whole. However, the inner structure of the large-diameter conductor cannot be accurately matched with that of the small-diameter conductor, which is prone to cause conductor misalignment and single-wire overlap disorder. At the same time, defects such as virtual welding and stress residue frequently occur, and the tensile and bending resistance of the joint is much lower than that of the submarine cable body, which is difficult to withstand the complex external forces brought by submarine currents and geological subsidence. In addition, the sudden change in the outer diameter of the joint part after the unequal-diameter conductor butt joint will not only damage the laying flatness of the subsequent semi-conductive shielding layer and insulating layer, but also cause stress concentration due to the sudden change in structure, which greatly reduces the service life and operational stability of the submarine cable joint, and cannot meet the stringent requirements of deep-sea projects for high reliability and long-period stable operation of submarine cable splicing joints. SUMMARY

[0004] In view of the above technical problems, the present application provides a submarine cable splicing method.

[0005] The present application provides a submarine cable splicing method, comprising the following steps: stripping the non-conductor layer of the end head of a first cable and a second cable, the conductor of the first cable being a first conductor, the conductor of the second cable being a second conductor, the diameter of the first conductor being smaller than the diameter of the second conductor; opening each layer of conductor filaments of the second conductor from the outside to the inside layer by layer, measuring the cross-sectional diameter of each layer before opening the next layer, marking the layer of conductor filaments whose first cross-sectional diameter and the diameter of the first conductor differ within a target value as a target layer, and after marking, no longer measuring the diameter and continuing to open the remaining conductor filaments layer by layer to expose the center filament of the second conductor; opening each layer of conductor filaments of the first conductor from the outside to the inside layer by layer to expose the center filament of the first conductor; splicing the center filaments of the first conductor and the second conductor; grouping and centering the conductor filaments of each layer within the target layer of the second conductor and the corresponding layer of the first conductor layer by layer and butt-welding; rotating and twisting each layer of the butt-jointed conductor filaments and spot-welding for reinforcement; and wrapping and welding the conductor filaments of the target layer and each layer outside the target layer of the second conductor from the inside to the outside layer by layer to the outside of the end head of the first conductor.

[0006] According to a submarine cable splicing method provided by the present invention, the diameter of the center wire of the first conductor and the diameter of the center wire of the second conductor are equal.

[0007] The steps of connecting the center wires of the first conductor and the second conductor specifically include: grinding the ends of both the center wires of the first conductor and the center wires of the second conductor into a conical shape, and connecting them by cold pressing; grinding the cold-pressed connection position until its cross-sectional diameter is consistent with the diameter of the center wire of the first conductor.

[0008] According to a submarine cable splicing method provided by the present invention, in the step of aligning and welding the conductor monofilaments of each layer within the target layer of the second conductor with the conductor monofilaments of the corresponding layer of the first conductor layer by layer, each layer of conductor monofilaments is grouped according to a preset number, and each group of conductor monofilaments to be spliced ​​is placed in the welding device in sequence to complete straightening, alignment, welding and stress release.

[0009] According to a submarine cable splicing method provided by the present invention, the welding device includes: a first half-base, wherein a plurality of first trapezoidal semi-grooves are formed therein; a second half-base, wherein a plurality of second trapezoidal semi-grooves are formed thereon, each of the second trapezoidal semi-grooves being adapted to each of the first trapezoidal semi-grooves to correspondingly connect and jointly form a plurality of trapezoidal centering grooves, each of the trapezoidal centering grooves being used for straightening and centering the corresponding group of conductor monofilaments; a driving device, wherein the driving device is connected to the first half-base and the second half-base and is used to drive the first half-base and / or the second half-base to move in a direction closer to or further away from each other; and a current module, wherein the current module is arranged in the first trapezoidal semi-grooves and the second trapezoidal semi-grooves to provide multiple current levels for the first trapezoidal semi-grooves and the second trapezoidal semi-grooves, wherein the multiple current levels include at least: a preheating level, a welding level, and a stress relief level.

[0010] According to a submarine cable splicing method provided by the present invention, after the welding operation and before the stress relief operation, the method further includes: grinding the welding position so that the cross-sectional diameter of the welding position is consistent with the diameter of the conductor monofilament to be welded.

[0011] According to a submarine cable splicing method provided by the present invention, the step of rotating and twisting each mating conductor monofilament layer and spot welding for reinforcement specifically includes: twisting each mating conductor monofilament layer in a clockwise direction; and spot welding each conductor monofilament in the same layer using argon arc welding.

[0012] The step of wrapping and welding the conductor wires of the target layer and its outer layers of the second conductor to the outer end of the first conductor layer by layer from the inside out to form a transition step structure on the outer end of the first conductor specifically includes: grinding the ends of the conductor wires in the target layer and its outer layers of the second conductor into a slope shape; wrapping the innermost conductor wire after the slope grinding is completed to the outer end of the first conductor; fixing the whole in an auxiliary shaping device; welding and grinding to form a first-level transition step; if the target layer and its outer layers of the second conductor have multiple conductor wires, then wrapping, fixing, welding and grinding are performed layer by layer from the inside out according to the above steps, and the length of the transition step decreases step by step after each layer of conductor wires is restored from the inside out to form a multi-level continuous transition step.

[0013] According to a submarine cable splicing method provided by the present invention, the auxiliary shaping device includes: a shaping base, wherein a gradient semi-groove is provided on the shaping base along the axial direction, the gradient semi-groove is adapted to each level of the transition step, the gradient semi-groove is used to fix the transition step, and the opening of the gradient semi-groove forms a welding joint.

[0014] The steps of fixing the whole in the auxiliary shaping device, welding and grinding to form a first-level transition step specifically include: embedding the wrapped conductor monofilament and the first conductor end into the gradient half groove; welding the area exposed at the weld joint; rotating the shaping seat to expose the unwelded areas in sequence and complete the full circumference welding; removing the auxiliary shaping device and grinding the weld joint to form a continuous transition step with a slope of less than or equal to 50°.

[0015] According to a submarine cable splicing method provided by the present invention, after the step of wrapping and welding the conductor monofilaments of the target layer and each outer layer of the second conductor to the outer end of the first conductor layer by layer from the inside out, the method further includes: wrapping a semi-conductive shielding tape around the outside of the mating conductor formed by the first cable and the second cable to make the mating conductor form a uniform cross-section; wrapping the semi-conductive shielding tape around the outside of the uniform cross-section; wrapping a high-temperature tightening tape around the outside of the current outermost semi-conductive shielding tape; repeatedly heating and pressing the high-temperature tightening tape with a heating gun to completely melt and bond the semi-conductive shielding tape; cooling and removing the high-temperature tightening tape; and polishing the semi-conductive shielding tape to form a semi-conductive shielding layer.

[0016] According to a submarine cable splicing method provided by the present invention, after the step of polishing the semi-conductive shielding layer, the method further includes: peeling off the shielding layer of a predetermined length segment of the first cable and the second cable connected to the joint; placing the joint and the two sections of cable with peeled shielding layers as a whole into the injection cavity of the covering container; injecting insulating material into the injection cavity through an external extruder and cooling it to cover the outside of the joint and the two sections of cable with peeled shielding layers as a whole with an inner insulating layer; replacing the covering container and continuing to cover the outside of the inner insulating layer with an outer insulating layer using the above steps.

[0017] According to a submarine cable splicing method provided by the present invention, after the step of continuing to wrap an outer insulation layer on the outside of the inner insulation layer, the method further includes: wrapping a semi-conductive shielding tape around the outside of the outer insulation layer; wrapping a high-temperature tightening tape around the outside of the current outermost semi-conductive shielding layer; repeatedly heating and pressing the high-temperature tightening tape with a heating gun to completely melt and bond the current outermost semi-conductive shielding tape; cooling and removing the high-temperature tightening tape; polishing the current outermost semi-conductive shielding tape to form an insulating shielding layer; wrapping multiple layers of semi-conductive resistive water tape around the outside of the insulating shielding layer; and sequentially wrapping a metal sleeve and a plastic sleeve around the outside of the outermost semi-conductive resistive water tape from the inside out.

[0018] The submarine cable splicing method provided by this invention includes the following steps: stripping the non-conductor layers from the ends of the first cable and the second cable, wherein the conductor of the first cable is the first conductor and the conductor of the second cable is the second conductor, and the diameter of the first conductor is smaller than the diameter of the second conductor; opening each layer of conductor filaments of the second conductor layer by layer from the outside in, measuring the cross-sectional diameter of each layer before opening, and marking the first conductor filament layer whose cross-sectional diameter is within the target value as the target layer, and after marking, no further diameter measurement is performed and the remaining conductor filaments are opened layer by layer until the center filament of the second conductor is exposed; opening each layer of conductor filaments of the first conductor layer by layer from the outside in until the center filament of the first conductor is exposed; splicing the center filaments of the first conductor and the center filaments of the second conductor; grouping and aligning each layer of conductor filaments within the target layer of the second conductor with the corresponding layer of conductor filaments of the first conductor layer by layer; rotating and twisting each mating conductor filament layer and spot welding for reinforcement; wrapping the target layer of the second conductor and the conductor filaments of each layer outside it layer by layer from the inside out and welding them to the outside of the end of the first conductor.

[0019] In summary, a complete conductor splicing process for unequal-diameter submarine cables is constructed through a comprehensive approach: hierarchical screening to establish benchmarks, core alignment to determine the foundation, inner layer group welding to ensure accuracy, and outer layer progressive wrapping to eliminate abrupt changes. First, target layers matching the first and second conductors are selected through dimensional measurements. Then, the center wire splicing, inner layer corresponding layer single-wire grouping and centering welding, and butt joint layer twisting and spot welding reinforcement are completed sequentially. Finally, the outer layer of the second conductor is progressively wrapped and welded to achieve integrated, highly adaptable splicing of the two unequal-diameter submarine cable conductors.

[0020] In the specific operation process, the cable end pre-processing is carried out first: the ends of the first cable and the second cable are processed respectively, all non-conductor layers at the end position are stripped to expose the conductor part to be connected, namely the first conductor of the first cable and the second conductor of the second cable.

[0021] Conductor layer stripping and matching layer selection: For the second conductor with a larger diameter, each layer of conductor wires is stripped layer by layer from the outside in. Before stripping each layer, the cross-sectional diameter of that layer is measured using a measuring tool until the first conductor wire layer whose cross-sectional diameter difference from the diameter of the first conductor is within the target range is found. This layer is marked as the target layer for the first conductor. After determining the target layer, there is no need to measure the cross-sectional diameter again. Continue stripping the remaining conductor wires of the second conductor layer by layer from the outside in until the center wire of the second conductor is fully exposed. Simultaneously, the layer stripping operation of the first conductor is carried out, using the same stripping tool as the second conductor, stripping each layer of conductor wires of the first conductor layer by layer from the outside in until the center wire of the first conductor is exposed.

[0022] Perform conductor center wire splicing: Complete the butt joint splicing of the first conductor center wire and the second conductor center wire. The connection of the center wires establishes the coaxial reference of the two conductors, realizes the axial positioning of the splicing part, and provides an axial reference for subsequent single wire welding.

[0023] Layered and grouped welding of inner conductor single wires: Taking the selected target layer as the boundary, for each layer of conductor single wires within the target layer of the second conductor and the corresponding layer of conductor single wires of the first conductor, the center welding is completed layer by layer and grouped according to the principle of one-to-one correspondence between the layers, so as to achieve a precise and orderly connection of the inner layer structure of the two conductors.

[0024] Reinforcement through twisting and spot welding of the mating layers: The single conductor wires of each layer that have been welded are rotated and twisted to ensure that the single wires in the same layer are tightly attached and neatly arranged. Then, the twisted single wire layer is reinforced by spot welding to further improve the integrity and connection strength of the inner layer mating structure.

[0025] Perform outer monofilament sheathing welding: Starting with the target layer, the target layer and all the conductor monofilaments on the outside of it in the second conductor are sheathed layer by layer on the outside of the end of the first conductor in the order from the inside to the outside, and the welding of the sheathed part is completed to form a transition step structure on the outside of the end of the first conductor. The two conductors of unequal diameter are connected by sheathing layer by layer to complete the splicing operation of the entire unequal diameter submarine cable conductor.

[0026] It should be noted that the axial length of the target layer and all layers outside the target layer needs to be greater than the axial length of all layers inside the target layer, so that the target layer and all layers outside the target layer can cover the outer side of the end of the first conductor and form a transition step structure on the outer side of the end of the first conductor.

[0027] This submarine cable splicing method first establishes a matching benchmark between the second and first conductors by measuring the diameter layer by layer and selecting the target layer. This ensures that the inner monofilaments are strictly connected according to their corresponding levels, completely avoiding problems such as disordered monofilament overlaps and misalignments, and guaranteeing the regularity of the joint's internal structure. Secondly, a refined welding mode of layer-by-layer grouping and centering welding, combined with rotational twisting and spot welding reinforcement, significantly improves the accuracy and strength of the monofilament connection, reduces welding defects, and greatly enhances the joint's tensile and bending mechanical properties. Furthermore, by welding the second conductor target layer and the outer monofilaments layer by layer from the inside out, a smooth transition structure is formed after splicing conductors of unequal diameters. This eliminates abrupt changes in the outer diameter at the joint, avoiding the risk of joint breakage due to structural stress concentration. It also provides a foundation for the smooth laying of subsequent shielding and insulation layers, preventing electrical faults such as electric field concentration and insulation cracking caused by structural abrupt changes, and ensuring the electrical performance and operational stability of the joint. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a simplified schematic diagram of the docking state structure of the first conductor and the second conductor in the spliced ​​submarine cable provided by the present invention.

[0030] Figure 2 This is a simplified schematic diagram of the welding device in this invention; Figure 3 This is a simplified schematic diagram of the structure of the covering container in this invention.

[0031] Figure 4 This is a simplified structural diagram of the auxiliary shaping device in this invention.

[0032] Reference numerals: 110, first half seat; 120, second half seat; 130, driving device; 200, shaping seat; 210, gradient half groove; 300, covering container; 310, glue injection cavity. Detailed Implementation

[0033] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0034] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0036] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0037] In the description of this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The following is combined with Figures 1 to 4 A submarine cable splicing method provided by an embodiment of the present invention will be described below. It should be understood that the following description is merely an illustrative embodiment of the present invention and does not constitute any particular limitation on the present invention.

[0039] An embodiment of the present invention provides a submarine cable splicing method, comprising the following steps: stripping the non-conductor layers of the ends of a first cable and a second cable, wherein the conductor of the first cable is the first conductor and the conductor of the second cable is the second conductor, and the diameter of the first conductor is smaller than the diameter of the second conductor; opening each layer of conductor filaments of the second conductor layer by layer from the outside in, measuring the cross-sectional diameter of each layer before opening, marking the first conductor filament layer whose cross-sectional diameter is within a target value of the first conductor diameter as the target layer, and after marking, no further diameter measurement is performed and the remaining conductor filaments are opened layer by layer until the center filament of the second conductor is exposed; opening each layer of conductor filaments of the first conductor layer by layer from the outside in until the center filament of the first conductor is exposed; splicing the center filaments of the first conductor and the center filaments of the second conductor; grouping and aligning each layer of conductor filaments within the target layer of the second conductor with the corresponding layer of conductor filaments of the first conductor layer by layer; rotating and twisting each mating conductor filament layer and spot welding for reinforcement; wrapping the target layer of the second conductor and the conductor filaments of each layer outside it layer by layer from the inside out and welding them to the outside of the end of the first conductor to form a transition step structure on the outside of the end of the first conductor.

[0040] In summary, a complete conductor splicing process for unequal-diameter submarine cables is constructed through a comprehensive approach: hierarchical screening to establish benchmarks, core alignment to determine the foundation, inner layer group welding to ensure accuracy, and outer layer progressive wrapping to eliminate abrupt changes. First, target layers matching the first and second conductors are selected through dimensional measurements. Then, the center wire splicing, inner layer corresponding layer single-wire grouping and centering welding, and butt joint layer twisting and spot welding reinforcement are completed sequentially. Finally, the outer layer of the second conductor is progressively wrapped and welded to achieve integrated, highly adaptable splicing of the two unequal-diameter submarine cable conductors.

[0041] In the specific operation process, such as Figure 1 As shown, the cable ends are pre-processed first: the ends of the first cable and the second cable are processed respectively, and all non-conductor layers at the end position are stripped to expose the conductor parts to be connected, namely the first conductor of the first cable and the second conductor of the second cable.

[0042] Conductor layer stripping and matching layer selection: For the second conductor with a larger diameter, each layer of conductor wires is stripped layer by layer from the outside in. Before stripping each layer, the cross-sectional diameter of that layer is measured using a measuring tool until the first conductor wire layer whose cross-sectional diameter difference from the diameter of the first conductor is within the target range is found. This layer is marked as the target layer for the first conductor. After determining the target layer, there is no need to measure the cross-sectional diameter again. Continue stripping the remaining conductor wires of the second conductor layer by layer from the outside in until the center wire of the second conductor is fully exposed. Simultaneously, the layer stripping operation of the first conductor is carried out, using the same stripping tool as the second conductor, stripping each layer of conductor wires of the first conductor layer by layer from the outside in until the center wire of the first conductor is exposed.

[0043] Perform conductor center wire splicing: Complete the butt joint splicing of the first conductor center wire and the second conductor center wire. The connection of the center wires establishes the coaxial reference of the two conductors, realizes the axial positioning of the splicing part, and provides an axial reference for subsequent single wire welding.

[0044] Layered and grouped welding of inner conductor single wires: Taking the selected target layer as the boundary, for each layer of conductor single wires within the target layer of the second conductor and the corresponding layer of conductor single wires of the first conductor, the center welding is completed layer by layer and grouped according to the principle of one-to-one correspondence between the layers, so as to achieve a precise and orderly connection of the inner layer structure of the two conductors.

[0045] Reinforcement through twisting and spot welding of the mating layers: The single conductor wires of each layer that have been welded are rotated and twisted to ensure that the single wires in the same layer are tightly attached and neatly arranged. Then, the twisted single wire layer is reinforced by spot welding to further improve the integrity and connection strength of the inner layer mating structure.

[0046] Perform outer monofilament sheathing welding: Starting with the target layer, the target layer and all the conductor monofilaments on the outside of it in the second conductor are sheathed layer by layer on the outside of the end of the first conductor in the order from the inside to the outside, and the welding of the sheathed part is completed to form a transition step structure on the outside of the end of the first conductor. The two conductors of unequal diameter are connected by sheathing layer by layer to complete the splicing operation of the entire unequal diameter submarine cable conductor.

[0047] It should be noted that the axial length of the target layer and all layers outside the target layer needs to be greater than the axial length of all layers inside the target layer, so that the target layer and all layers outside the target layer can cover the outer side of the end of the first conductor and form a transition step structure on the outer side of the end of the first conductor.

[0048] This submarine cable splicing method first establishes a matching benchmark between the second and first conductors by measuring the diameter layer by layer and selecting the target layer. This ensures that the inner monofilaments are strictly connected according to their corresponding levels, completely avoiding problems such as disordered monofilament overlaps and misalignments, and guaranteeing the regularity of the joint's internal structure. Secondly, a refined welding mode of layer-by-layer grouping and centering welding, combined with rotational twisting and spot welding reinforcement, significantly improves the accuracy and strength of the monofilament connection, reduces welding defects, and greatly enhances the joint's tensile and bending mechanical properties. Furthermore, by welding the second conductor target layer and the outer monofilaments layer by layer from the inside out, a smooth transition structure is formed after splicing conductors of unequal diameters. This eliminates abrupt changes in the outer diameter at the joint, avoiding the risk of joint breakage due to structural stress concentration. It also provides a foundation for the smooth laying of subsequent shielding and insulation layers, preventing electrical faults such as electric field concentration and insulation cracking caused by structural abrupt changes, and ensuring the electrical performance and operational stability of the joint.

[0049] For each cable, namely a submarine cable, it consists of, from the inside out, a conductor, a shielding layer, an insulation layer, an insulation shielding layer, a semi-conductive resistive water layer, a metal sheath, a plastic sheath, filler, high-strength wrapping tape, a polypropylene inner padding layer, a metal wire armor layer, a polypropylene outer sheath, and an optical fiber unit.

[0050] In one embodiment of the present invention, the diameter of the center wire of the first conductor and the diameter of the center wire of the second conductor are equal.

[0051] The steps of connecting the center wires of the first conductor and the second conductor specifically include: grinding the ends of both the center wires of the first conductor and the center wires of the second conductor into a conical shape, and connecting them by cold pressing; grinding the cold-pressed connection position until its cross-sectional diameter is consistent with the diameter of the center wire of the first conductor.

[0052] In one embodiment of the present invention, in the step of aligning and welding the conductor wires of each layer within the target layer of the second conductor with the conductor wires of the corresponding layer of the first conductor layer by layer, each layer of conductor wires is grouped according to a preset number, and each group of conductor wires to be joined is placed in the welding device in sequence to complete straightening, alignment, welding and stress release.

[0053] In one embodiment of the present invention, such as Figure 2 As shown, the welding device includes: a first half-base 110, in which a plurality of first trapezoidal half-grooves are formed; a second half-base 120, on which a plurality of second trapezoidal half-grooves are formed, each second trapezoidal half-groove being adapted to each of the first trapezoidal half-grooves to correspondingly connect and jointly form a plurality of trapezoidal centering grooves, each trapezoidal centering groove being used for straightening and centering the corresponding group of conductor wires; a driving device 130, which is connected to the first half-base 110 and the second half-base 120 and is used to drive the first half-base 110 and / or the second half-base 120 to move in a direction closer to or further away from each other; and a current module, which is arranged in the first trapezoidal half-grooves and the second trapezoidal half-grooves to provide multiple current levels for the first trapezoidal half-grooves and the second trapezoidal half-grooves, the multiple current levels including at least: a preheating level, a welding level, and a stress relief level.

[0054] In one embodiment of the invention, after the welding operation and before the stress relief operation, the method further includes: grinding the welding position so that the cross-sectional diameter of the welding position is consistent with the diameter of the conductor monofilament to be welded.

[0055] In one embodiment of the present invention, the step of rotating and twisting each mating conductor monofilament layer and spot welding for reinforcement specifically includes: twisting each mating conductor monofilament layer in a clockwise direction; and spot welding each conductor monofilament in the same layer using argon arc welding.

[0056] The steps of wrapping and welding the conductor wires of the target layer and its outer layers of the second conductor to the outer end of the first conductor layer by layer from the inside out are specifically included: grinding the ends of the conductor wires in the target layer and its outer layers of the second conductor into a slope shape; wrapping the innermost conductor wire with the sloped grinding to the outer end of the first conductor; fixing the whole in an auxiliary shaping device; welding and grinding to form a first-level transition step; if the target layer and its outer layers of the second conductor have multiple conductor wires, then wrapping, fixing, welding and grinding are performed layer by layer from the inside out according to the above steps, and the length of the transition step decreases step by step after each layer of conductor wires is restored from the inside out, so as to form a multi-level continuous transition step.

[0057] In one embodiment of the present invention, such as Figure 4As shown, the auxiliary shaping device includes: a shaping base 200, on which a gradient half-groove 210 is provided along the axial direction. The gradient half-groove 210 is adapted to each level of transition steps. The gradient half-groove 210 is used to fix the transition steps. The opening of the gradient half-groove 210 forms a welding joint.

[0058] The steps of fixing the whole in the auxiliary shaping device, welding and grinding to form a first-level transition step include: embedding the wrapped conductor monofilament and the first conductor end into the gradient half groove 210; welding the area exposed at the weld joint; rotating the shaping seat 200 to expose the unwelded areas in sequence and complete the full circumference welding; removing the auxiliary shaping device and grinding the weld joint to form a continuous transition step with a slope of less than or equal to 50°.

[0059] Specifically, during the splicing of the two cable conductors, a pre-treatment of the cable ends is first performed. A 20cm-30cm length mark is precisely measured at the ends of the first conductor of the first cable and the second conductor of the second cable. Using a specialized wire stripping tool, all non-conductive layers within this marked area are stripped. After stripping, a tapered shape is left at each conductor end, with the tapered angle controlled between 60° and 70°. This tapered shape is used for the subsequent wrapping and transition of the outer conductor filaments, effectively reducing stress concentration at the joint. Simultaneously, the exposed surfaces of the two conductors are lightly sanded with fine sandpaper to remove the oxide layer and stains, ensuring the fit and conductivity of the subsequent conductor splice. The diameter of the first conductor is smaller than the diameter of the second conductor; for example, the first conductor diameter is 20mm and the second conductor diameter is 30mm.

[0060] After preprocessing, the conductor layering and matching layer screening steps begin. For the second conductor with a larger diameter, each conductor filament layer is peeled off layer by layer from the outside in. Before peeling off each conductor filament layer, the cross-sectional diameter of that layer is measured, and a target value for the diameter difference is set at 3mm. This measurement and peeling continues layer by layer until the first conductor filament layer whose cross-sectional diameter difference from the diameter of the first conductor is within 3mm is found. This layer is marked as the target layer for the first conductor. After the target layer is marked, it is no longer necessary to measure the cross-sectional diameter of the remaining conductor filament layers of the second conductor. The remaining conductor filament layers of the second conductor are peeled off layer by layer from the outside in until the center filament of the second conductor is completely exposed. The same layering and peeling operation is performed on the first conductor from the outside in, peeling off each conductor filament layer of the first conductor from the outside in until the center filament of the first conductor is completely exposed.

[0061] Next, the conductor center wire splicing operation is performed. For example, the diameters of the center wires of the first and second conductors are equal. Using an angle grinder with a fine grinding wheel, the ends of both the first and second conductor center wires are ground into conical shapes, with the cone angle controlled between 50° and 60° to ensure smooth, burr-free ends. After grinding, the conical ends of the two center wires are aligned and a cold-press splicing tool is used. During the cold-pressing process, the pressure is kept uniform and stable to ensure a tight, secure, and gap-free connection between the two center wires. After the cold-pressing splice is completed, the joint area is sanded with fine sandpaper, repeatedly sanding until its cross-sectional diameter matches the diameter of the first conductor's center wire, avoiding irregularities such as protrusions or depressions, and ensuring a smooth and regular splice.

[0062] After the center wire is spliced, the inner conductor wires are grouped and welded layer by layer. Using the previously selected target layer as the boundary, each layer of conductor wires within the target layer of the second conductor is welded to the corresponding layer of conductor wires in the first conductor, following a one-to-one correspondence principle. Each layer of conductor wires is grouped into groups of 3-4 wires. After grouping, each group of conductor wires to be welded is placed sequentially in a dedicated welding device to complete the entire process of straightening, centering, welding, and stress release. The welding device includes a first half-seat 110, a second half-seat 120, a drive device 130, and a current module. The first half-base 110 has multiple first trapezoidal semi-grooves, and the second half-base 120 has multiple second trapezoidal semi-grooves that are one-to-one matched with the first trapezoidal semi-grooves. After each first trapezoidal semi-groove and its corresponding second trapezoidal semi-groove are aligned, they together form multiple trapezoidal alignment grooves. These trapezoidal alignment grooves are adapted to the conductor wires, enabling precise straightening and alignment of each group of conductor wires to be aligned, preventing wire offset or misalignment. The driving device 130 is connected to the first half-base 110 and the second half-base 120, and can drive the first half-base 110 and / or the second half-base 120 to move in a direction closer to or further away from each other, realizing the opening and closing of the welding device, facilitating the placement and removal of the wires. For example, the driving device 130 may include a first hydraulic cylinder and a second hydraulic cylinder, with the first hydraulic cylinder connected to the first half-base 110 and the second hydraulic cylinder connected to the second half-base 120. The current modules are installed in the first and second trapezoidal half-slots, providing multiple current levels for the conductor wires within the slots, including at least a preheating level, a welding level, and a stress relief level. For example, the preheating level corresponds to a current output of 300A, the welding level corresponds to a current output of 800~1000A, and the stress relief level corresponds to a current output of 200A, meeting the current requirements of different processes.

[0063] For example, such as Figure 2As shown, the welding device has five trapezoidal alignment slots, allowing for the simultaneous welding of five sets of conductor wires. During the welding operation, the conductor wires to be joined are placed into the first and second trapezoidal half-slots respectively, and the drive device 130 drives the second half-slot 120 closer to the first half-slot 110. Furthermore, a longitudinal drive structure can be provided to adjust the axial height of the first and second trapezoidal half-slots. The trapezoidal alignment slots are used to straighten and center the wires, ensuring that the axes of the two joined wires are completely aligned. Subsequently, the current module power is turned on, and the device is switched to the preheating position for 5 seconds. After preheating, the device is switched to the welding position for 10 seconds to achieve a firm fusion and pressing of the single wire joint, ensuring that the welding strength meets the standard. After welding and pressing, the drive device 130 is controlled to separate the first half-seat 110 and the second half-seat 120, that is, to open the welding device. A file and 300-grit sandpaper are used to polish the welding point until it is smooth and round, ensuring that the outer diameter of the welding part is consistent with the diameter of the single wire of the conductor being connected, and eliminating welding protrusions and burrs. After polishing, the first half-seat 110 and the second half-seat 120 are closed again by the drive device 130, the power is turned on and the device is switched to the stress release position for 2 seconds to effectively release the residual stress generated during the welding process and prevent the single wire from cracking or breaking due to stress concentration. After stress release, the first half-seat 110 and the second half-seat 120 are opened and the connected single wire of the conductor is taken out. Following the above procedure, the alignment and welding of each layer of single wires within the second conductor target layer and the corresponding layer of single wires in the first conductor are completed layer by layer and group by group.

[0064] After all the inner conductor wires are welded in layers and groups, the conductor wire layers are rotated and twisted clockwise to form a whole, improving the compactness of the inner layer connection structure. After twisting, argon arc welding equipment is used to spot weld and reinforce the conductor wires in the same layer. During spot welding, the weld size is controlled to ensure that the welds are firm and free of defects. Spot welding further locks the position of the conductor wires, preventing the inner layer wires from loosening or spreading during the subsequent outer layer wire wrapping operation, thus ensuring the integrity and stability of the inner layer connection structure.

[0065] Subsequently, the ends of each conductor wire in the target layer and its outermost layers in the second conductor are finely polished, shaping the wire ends into a bevel with an angle controlled within the range of 60°-70°. After polishing, following an inward-outward sequence, the conductor wire of the innermost layer, i.e., the target layer, is uniformly wrapped around the outer side of the first conductor end. The wrapped overall structure is then placed into an auxiliary shaping device for fixation. Specifically, the auxiliary shaping device includes a shaping base 200, on which a gradient half-groove 210 is axially formed. The gradient half-groove 210 is adapted to each level of transition steps, used to fix the transition steps formed between each layer of wrapped conductor wire and the first conductor end. The open portion of the gradient half-groove 210 forms a welding joint, providing space for welding operations. After the conductor monofilament and the first conductor end are fully encased, they are embedded into the gradient half-groove 210. The exposed areas are welded through the welding joint of the gradient half-groove 210. After one side of the area is welded, the shaping seat 200 is slowly rotated so that the unwelded areas are exposed to the welding joint in turn, and the full circumference welding is completed step by step. After the full circumference welding is completed, the welded part is cooled to room temperature, the auxiliary shaping device is removed, and the welded part is polished with fine sandpaper to make the part a first-level transition step with a slope of ≤50°.

[0066] If the second conductor target layer and its outer side have multiple conductor single-wire layers, then the above process is repeated layer by layer from the inside out, and the length of the transition step after the single-wire is formed in each layer from the inside out is controlled to decrease step by step, such as... Figure 1 As shown, this ultimately forms a multi-level, continuous, smooth transition step.

[0067] In one embodiment of the present invention, after the step of wrapping and welding the conductor monofilaments of the target layer and each outer layer of the second conductor to the outer end of the first conductor layer by layer from the inside out, the method further includes: wrapping a semiconductive shielding tape around the outside of the mating conductor formed by the first cable and the second cable to make the mating conductor form a uniform cross-section; wrapping the semiconductive shielding tape around the outside of the uniform cross-section; wrapping a high-temperature tightening tape around the outside of the current outermost semiconductive shielding tape; repeatedly heating and pressing the high-temperature tightening tape with a heating gun to completely melt and bond the semiconductive shielding tape; cooling and removing the high-temperature tightening tape; and polishing the semiconductive shielding tape to form a semiconductive shielding layer.

[0068] In another embodiment of the present invention, after the step of polishing the semiconductive shielding layer, the method further includes: peeling off the shielding layer of the first cable and the second cable of a predetermined length connected to the connector; placing the connector and the two sections of cable with peeled shielding layers inside the injection cavity 310 of the covering container 300; injecting insulating material into the injection cavity 310 through an external extruder and cooling it to cover the connector and the two sections of cable with peeled shielding layers with an inner insulating layer on the outside of the connector; replacing the covering container 300 and continuing to cover the outer side of the inner insulating layer with an outer insulating layer using the above steps.

[0069] In one embodiment of the present invention, after the step of continuing to cover the outer side of the inner insulating layer with an outer insulating layer, the method further includes: wrapping a semiconductive shielding tape around the outer side of the outer insulating layer; wrapping a high-temperature tightening tape around the outer side of the current outermost semiconductive shielding layer; repeatedly heating and pressing the high-temperature tightening tape with a heating gun to completely melt and bond the current outermost semiconductive shielding tape; cooling and removing the high-temperature tightening tape; polishing the current outermost semiconductive shielding tape to form an insulating shielding layer; wrapping multiple layers of semiconductive resistive water tape around the outer side of the insulating shielding layer; and sequentially wrapping a metal sleeve and a plastic sleeve around the outer side of the outermost semiconductive resistive water tape from the inside out.

[0070] In other words, after the second conductor target layer and the outer monofilament coating welding are completed, the multi-level transition steps are formed, and the joint area has completely cooled to room temperature, the semiconductive shielding layer restoration process is carried out. Specifically, the first layer of semiconductive shielding is first applied. For example, the semiconductive shielding layer is formed by wrapping a semiconductive polyolefin shielding tape. The semiconductive shielding tape is formed by extrusion using a high-purity special semiconductive shielding material, with the tape thickness controlled at 1.0mm ± 0.2mm. The overall material properties must meet the following requirements: density not greater than 1.10g / cm³. 3The tensile strength is not less than 25 MPa, the volume resistivity at 90℃ is not greater than 80 Ω·cm, and the deformation rate after heat deformation treatment at 120℃ for 1 hour is not greater than 10%. A semi-conductive polyolefin shielding tape is tightly and uniformly wound around the outer side of the conductor formed by the first and second cables, filling the transition steps through multiple layers of winding to form a regular, uniform cross-section around the entire conductor. After the uniform cross-section is formed, the same semi-conductive polyolefin shielding tape is used again to uniformly wrap multiple layers around its outer periphery according to the same winding requirements. After this layer of shielding tape is completed, a semi-conductive shielding base layer to be bonded is formed. Subsequently, a high-temperature tightening tape, for example, polytetrafluoroethylene high-temperature tape, is tightly wound around the outer periphery of the semi-conductive shielding base layer using an overlapping winding method. The tightening tape's binding effect provides uniform radial pressure for subsequent heat bonding, ensuring that the semi-conductive polyolefin shielding tape can fit tightly without gaps during heating, guaranteeing the bonding effect. The high-temperature tightening tape is repeatedly heated using a heating gun. Specifically, the heating temperature is controlled at 100-120℃. For every 1 minute of heating, the material is pressed by hand for 10 seconds. This action is repeated for 20 minutes until the material is completely melted and bonded. Heating is then stopped, and the material is allowed to cool for 10 minutes. The high-temperature PTFE strip is then removed, and the surface is polished to a smooth finish. This forms the final semi-conductive shielding layer.

[0071] Subsequently, an insulating layer is wrapped around the outside of the semi-conductive shielding layer. The specific operation is as follows: Using the connector as the center, measure a predetermined length segment connected to the connector on both the first and second cables, for example, a predetermined length of 0.5m. Peel off the original outer shielding layer along this predetermined length segment. After peeling, refine the interface at the starting point of the shielding layer peeling, polishing it to be rounded and smooth, ensuring there are no protrusions, burrs, or sharp edges. For example... Figure 3 As shown, a pre-defined packaging container 300 is selected. The length of the injection cavity 310 of this packaging container 300 is at least sufficient to cover the sum of the stripped length of the first cable shielding layer, the length of the mating conductor, and the stripped length of the second cable shielding layer. For example, the length of the injection cavity 310 of the container is 3-5 mm larger than the sum of the stripped lengths of the first cable shielding layer, the mating conductor, and the second cable shielding layer. The diameter of the injection cavity 310 is 20 cm to 30 cm larger than the larger outer diameter of the first and second submarine cables after the shielding layers have been stripped.

[0072] The shielded portions of the first and second submarine cables, along with their joints, are placed entirely within the injection cavity 310 of the covering container 300. An external extruder is then tested, and cross-linkable polyethylene material is selected. This material requires a density ≤0.93 g / cm³, tensile strength ≥20 MPa, relative permittivity at 90℃ ≤2.30, dielectric loss factor at 90℃ ≤5×10⁻⁴, volume resistivity at 90℃ ≥1.5×10¹⁴ Ω·m, and dielectric strength 50 kV / mm. The cross-linkable polyethylene material is heated to a molten state using the extruder's heating extrusion function. The molten cross-linkable polyethylene material is then injected uniformly and smoothly into the injection cavity 310 and cooled to form the inner insulation layer.

[0073] Replace the inner insulation layer with a different type of encapsulation container 300. The diameter of the injection cavity 310 of this container 300 is 20cm to 30cm larger than the overall diameter of the inner insulation layer. Then, encapsulate the outer insulation layer on the outside of the inner insulation layer in the same manner. This achieves double-layer insulation encapsulation. Furthermore, through the above-described multiple injection molding encapsulation process, a stress-relieved insulation layer can be formed. After completing the outer insulation layer encapsulation, open the encapsulation container 300 and finely polish the outer surface of the outer insulation layer to ensure that the surface is smooth, round, and free of protrusions, depressions, and burrs.

[0074] After completing the insulation coating, the insulation shielding layer and external protective structure must be constructed sequentially. Specifically, firstly, a semi-conductive polyolefin shielding tape is evenly and tightly wrapped in multiple layers around the outer periphery of the outer insulation layer. Then, a polytetrafluoroethylene (PTFE) high-temperature tape is wrapped around the outside of this semi-conductive polyolefin shielding tape. A heating gun is used to circulate heat and press, allowing the semi-conductive polyolefin shielding tape to fully melt and bond together into a dense whole. After natural cooling and solidification, the PTFE high-temperature tape is removed, and the surface is then sanded with fine sandpaper until smooth and rounded, forming a continuous and dense insulation shielding layer. For example, the heating temperature is controlled at 100-120℃. For every 1 minute of heating, the surface is pressed by hand for 10 seconds, repeated for 60 minutes until completely melted and bonded. Heating is then stopped, and the surface is cooled for 20 minutes before removing the high-temperature tape and sanding it smooth.

[0075] After the insulation shielding layer is completed, it is wrapped with a 50% overlap on the outside, and two layers of semi-conductive resistive water tape are wrapped around it. The semiconducting water-resistant layer is composed of nonwoven fabric, semiconducting material, and water-blocking powder. The melt index of the nonwoven fabric is (8~10) g / 10min, the absorbance value of the conductive carbon black DBP of the semiconducting material is ≥200ml / 100g, and the expansion ratio of the water-blocking powder is required to be ≥500% (72h). The composite semiconducting water-resistant tape has a peel strength ≥5N / mm, a breaking strength of not less than 40N / cm, a breaking elongation of not less than 10%, a surface resistivity (23±2℃) ≤1500Ω, a volume resistivity at 23℃ ≤1×105Ω·cm, and a moisture content ≤5%. The water-blocking powder is a water-absorbing resin, mainly composed of specially treated water-absorbing resin particles and some performance-improving additives such as phosphonic acid chelating agents and benzimidazole compounds added to the base resin polypropylene. Among them, polypropylene accounts for 50%, phosphonic acid chelating agents account for 10%, and benzimidazole compounds account for 15%. By utilizing the water absorption and expansion characteristics of semiconducting resistive water tape, a multi-layer water-blocking barrier is constructed in the joint section to effectively prevent external seawater and moisture from penetrating into the internal insulation and shielding structure, prevent the insulation material from aging due to moisture and the shielding performance from failing, and ensure the long-term waterproof reliability of the joint.

[0076] After the semiconducting resistive water tape is applied, a metal sleeve and a plastic sleeve are wrapped around it from the inside out. For example, the metal sleeve is welded, and the plastic sheath is restored by heat bonding.

[0077] Then, the core wires are twisted together using a large-scale vertical cabling and metal wire armor production line, achieving one-time molding production of filler, high-strength wrapping tape, polypropylene inner padding layer, metal wire armor layer and polypropylene outer sheath layer, with each layer having the opposite direction.

[0078] The filler consists of polyethylene filler strips or recycled filler strips, used to support the stranded cores and ensure the cable's roundness. The high-strength wrapping tape is environmentally friendly, with a breaking strength of not less than 200 N / cm, used to tighten the stranded cores. The polypropylene inner padding layer and polypropylene outer sheath are twisted ropes made of polypropylene with a diameter ≥3.0 mm. The metal wire armor layer is made of galvanized steel wire, non-magnetic steel wire, or copper wire.

[0079] The above-mentioned submarine cable splicing method achieves several advantages. First, it enables precise alignment and welding of irregularly shaped monofilaments, ensuring a misaligned weld and a strong connection. The welding strength of the monofilament reaches 70% of the body strength, effectively improving the reliability of factory joint welding and guaranteeing the mechanical stability and electrical transmission safety of welded conductors with different cross-sections. Second, it allows for complete fusion of the inner layers of conductors with different materials and cross-sections, ensuring the joint's tensile strength meets standards. Simultaneously, it achieves a smooth transition at the splicing points of conductors with unequal cross-sections, enhancing the overall welding strength of the conductors. Third, it effectively reduces electric field concentration caused by excessively large inner layer steps during conductor shielding layer fabrication. This reduces potential hazards, minimizes conductor shielding material loss, ensures uniform connector outer diameter, and prevents conductor shielding layer cracking and delamination during cable bending, further enhancing electrical safety. Furthermore, it effectively addresses issues such as insufficient cross-linking and residual internal stress in the connector insulation layer, extending the lifespan of factory-made connectors while improving connector manufacturing efficiency and reducing insulation material usage. Finally, it enables reliable connection of conductors of various cross-sections, unrestricted by conductor cross-section size, improving process operability, expanding the overall application range, and ensuring that connector performance remains consistent with the submarine cable body, adapting to complex operating conditions in deep-sea environments.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of submarine cable jointing, characterised in that, The method comprises the following steps: stripping the non-conductor layer of the end of the first cable and the second cable, the conductor of the first cable being a first conductor, and the conductor of the second cable being a second conductor, the diameter of the first conductor being smaller than the diameter of the second conductor; opening each layer of the conductor filaments of the second conductor from the outside to the inside, layer by layer, and measuring the cross-sectional diameter of each layer before opening the next layer, and marking the layer of the conductor filaments whose cross-sectional diameter is within a target value of the diameter of the first conductor as a target layer, and after marking, no longer measuring the diameter and continuing to open the remaining conductor filaments layer by layer until the center filament of the second conductor is exposed; opening each layer of the conductor filaments of the first conductor from the outside to the inside until the center filament of the first conductor is exposed; connecting the center filament of the first conductor and the center filament of the second conductor; grouping and centering the conductor filaments of each layer within the target layer of the second conductor and the conductor filaments of the corresponding layer of the first conductor, layer by layer, and welding them; rotating and twisting each layer of the connected conductor filaments and spot welding for reinforcement; covering and welding the conductor filaments of the target layer and each layer outside the target layer of the second conductor to the outside of the end of the first conductor from the inside to the outside, layer by layer, to form a transition step structure on the outside of the end of the first conductor.

2. A method of submarine cable jointing according to claim 1, characterised in that, The diameter of the center filament of the first conductor is equal to the diameter of the center filament of the second conductor. The step of connecting the center filament of the first conductor and the center filament of the second conductor specifically comprises: polishing the end of the center filament of the first conductor and the end of the center filament of the second conductor into a conical shape, and cold-pressing and centering the two; polishing the cold-pressing connection position to a state where the cross-sectional diameter is consistent with the diameter of the center filament of the first conductor.

3. A method of submarine cable jointing according to claim 1, characterised in that, In the step of grouping and centering the conductor filaments of each layer within the target layer of the second conductor and the conductor filaments of the corresponding layer of the first conductor, layer by layer, and welding them, each layer of conductor filaments is grouped in a predetermined number, and each group of conductor filaments to be connected is sequentially placed in a welding device to complete straightening, centering positioning, welding, and stress relief.

4. A method of submarine cable jointing according to claim 3, characterised in that, The welding device comprises: a first half seat, a plurality of first trapezoidal half grooves are formed in the first half seat; a second half seat, a plurality of second trapezoidal half grooves are formed on the second half seat, each second trapezoidal half groove is matched with each first trapezoidal half groove one by one to correspondingly connect and jointly form a plurality of trapezoidal centering grooves, and each trapezoidal centering groove is used for straightening and centering positioning of the corresponding group of conductor filaments; a driving device connected with the first half seat and the second half seat, and used for driving the first half seat and / or the second half seat to move in a direction of approaching or moving away from each other; a current module arranged to the first trapezoidal half grooves and the second trapezoidal half grooves to provide a plurality of current positions for the first trapezoidal half grooves and the second trapezoidal half grooves, and the plurality of current positions at least include a preheating position, a welding position, and a stress relief position.

5. A method of submarine cable jointing according to claim 3, characterised in that, After the welding operation and before the stress relief operation, it further comprises: polishing the welding position to make the cross-sectional diameter of the welding position consistent with the diameter of the connected conductor filaments.

6. A method of submarine cable jointing according to claim 1 characterised in that, The step of rotating and twisting each layer of the connected conductor filaments and spot welding for reinforcement specifically comprises: twisting each layer of the connected conductor filaments in a clockwise direction; using argon arc welding to spot weld each conductor filament in the same layer; The step of covering and welding the conductor filaments in the target layer and each layer outside the target layer of the second conductor to the outside of the end of the first conductor layer by layer from inside to outside to form a transition step structure outside the end of the first conductor specifically comprises: Polishing the end of the conductor filaments in the target layer and each layer outside the target layer of the second conductor into a slope shape respectively; Covering the conductor filaments in the innermost layer after the slope polishing to the outside of the end of the first conductor, fixing the whole in the auxiliary shaping device, welding and polishing to form a first-level transition step; If the target layer of the second conductor and each layer outside the target layer have multiple layers of conductor filaments, the above steps are performed layer by layer from inside to outside, and the length of the transition step after the recovery of each layer of conductor filaments from inside to outside is gradually reduced to form a multi-level continuous transition step.

7. A method of submarine cable jointing according to claim 6, characterised in that, The auxiliary shaping device comprises: A shaping seat, wherein a gradient half-slot is arranged on the shaping seat in the axial direction, the gradient half-slot is matched with each level of the transition step, the gradient half-slot is used for fixing the transition step, and an opening of the gradient half-slot forms a welding interface; The step of fixing the whole in the auxiliary shaping device, welding and polishing to form a first-level transition step specifically comprises: Embedding the covered conductor filaments and the end of the first conductor into the gradient half-slot; Welding the area exposed to the welding interface; Rotating the shaping seat to expose the unwelded area in turn and complete the full-circle welding; Removing the auxiliary shaping device and polishing the welded area to form a continuous transition step with a slope less than or equal to 50°.

8. A method of joining marine cables according to any one of claims 1 to 7, characterised in that, After the step of covering and welding the conductor filaments in the target layer and each layer outside the target layer of the second conductor to the outside of the end of the first conductor layer by layer from inside to outside, the step further comprises: Winding and covering the semiconductive shielding tape to the outside of the butt joint conductor formed by the first cable and the second cable to make the butt joint conductor form an equal cross-section body; Winding and covering the semiconductive shielding tape to the outside of the equal cross-section body; Winding and covering the high-temperature tightening tape to the outside of the current outermost semiconductive shielding tape; Using a heating gun to heat and press the high-temperature tightening tape multiple times to make the semiconductive shielding tape completely melt and bond; Cooling and removing the high-temperature tightening tape; Polishing the semiconductive shielding tape to form a semiconductive shielding layer.

9. A method of joining marine cables as claimed in claim 8, characterised in that, After the step of polishing the semiconductive shielding layer, the step further comprises: Stripping the shielding layer of a preset length of the first cable and the second cable connected to the butt joint; Placing the butt joint and the two sections of the cable with the stripped shielding layer into the injection cavity of the covering container; Injecting an insulating material into the injection cavity through an external extruding machine and cooling to cover an inner insulating layer outside the butt joint and the two sections of the cable with the stripped shielding layer; Replacing the covering container and continuing to cover an outer insulating layer outside the inner insulating layer by using the above steps.

10. A method of joining marine cables as claimed in claim 9, characterised in that, After the step of continuing to cover an outer insulating layer outside the inner insulating layer, the step further comprises: Winding and covering the semiconductive shielding tape to the outside of the outer insulating layer; Winding and covering the high-temperature tightening tape to the outside of the current outermost semiconductive shielding layer; Using a heating gun to heat and press the high-temperature tightening tape multiple times to make the current outermost semiconductive shielding tape completely melt and bond; Cooling and removing the high-temperature tightening tape; Polishing the current outermost semiconductive shielding tape to form an insulating shielding layer; The insulating shielding layer is wrapped by the outer covering multilayer semiconductive water-blocking belt; The metal sleeve and the plastic sleeve are wrapped in turn from inside to outside outside the outermost semiconductive water-blocking belt.

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