A multi-core fan-shaped conductor compacted power cable and a production process

Abstract

The application discloses a kind of multi-core fan-shaped conductor tight forming power cable and production process, it is related to power cable technical field, to solve the technical problems that cable service process is prone to core misplacement, filling failure, internal air gap.It is optimized from conductor, assembly, filling, sealing, process, solve the defects such as traditional fan-shaped cable core misplacement, interface air gap, partial discharge, adopt multistage circular arc structure and layering tight pressing to conductor, eliminate sharp corner stress and electric field distortion;Through joint strip, cable sleeve combination preloading limit, avoid core overturning deviation, rely on groove structure and reverse spiral engagement, solve interface air gap, improve waterproof capacity, match partition perfusion process and addition type silicone rubber, filling is dense and forms integrated elastic structure, while using low-temperature curing process, protect insulation from damage, overall structure stability, electrical performance and anti-aging ability greatly improve, adapt to a variety of power distribution scenarios, prolong the service life of cable.

Description

Technical Field

[0001] This invention relates to the field of power cable technology, and more specifically, to a multi-core fan-shaped conductor compacted power cable and its manufacturing process. Background Technology

[0002] Multi-core sector-shaped conductor power cables are the mainstream cable products in medium and low voltage power transmission and distribution systems. Compared with traditional round conductor cables, sector-shaped conductors, through irregular compression molding design, can significantly reduce the overall outer diameter of the cable, reduce the amount of filler and sheath materials used, and improve the compactness of the cable core. They have significant advantages such as compact structure, high utilization of laying space, material saving, and good economy. They are widely used in large-scale power transmission and distribution scenarios such as urban power grids, industrial plants, and building power distribution, and represent an important development direction for energy-saving power cables. Currently, traditional multi-core sector-shaped conductor cables have inherent defects in their structural design, resulting in insufficient overall structural stability. Especially for short cables that need to be moved frequently, such as those used to connect electrical cabinets, they are prone to a series of problems such as core misalignment, filler failure, and internal air gaps during processing and long-term service, leading to potential dual degradation of electrical and mechanical properties and seriously affecting the long-term operational reliability of the cable.

[0003] Specifically, traditional fan-shaped conductor core structures suffer from insufficient limiting and adaptability design. During cable stranding and processing, thermal expansion and contraction caused by power grid load fluctuations, and bending and dragging during installation, the fan-shaped cores experience uneven stress in all directions, making them prone to circumferential flipping, misalignment, and other phenomena. This misalignment continuously compresses the internal filling structure of the core, causing the filling material to slip and leak, resulting in gaps and disrupting the original dense bonding structure. Consequently, numerous microscopic air gaps, invisible to the naked eye, form between the conductor and insulation layer, and between the core and filling layer.

[0004] On the one hand, the air gap at the interface disrupts the uniformity of the electric field distribution inside the cable, causing local electric field distortion and continuous partial discharge. Long-term discharge continuously erodes the aging insulation medium, leading to insulation carbonization and performance degradation, significantly increasing the safety risks of cable leakage, breakdown, and short circuits. On the other hand, the misalignment between the air gap and the conductor core disrupts the conductor's stress structure, causing extremely disordered stress distribution within the fan-shaped conductor. This exacerbates the concentration of mechanical stress in the conductor, making it prone to fatigue damage under long-term alternating stress, reducing the cable's resistance to bending and thermal deformation, and further greatly shortening the cable's service life and reducing the operational stability of the power distribution system. Therefore, we propose a multi-core fan-shaped conductor compacted power cable and its manufacturing process. Summary of the Invention

[0005] One of the objectives of this invention is to provide a multi-core fan-shaped conductor compacted power cable to solve the technical problems of wire core misalignment, filling failure, and internal air gaps that are prone to occur during long-term cable service.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a multi-core sector-shaped conductor compacted power cable, comprising:

[0007] Multiple twisted, spirally arranged fan-shaped conductors are used to transmit electricity;

[0008] An insulating outer layer, covering the outer periphery of multiple sector-shaped conductors, is used for insulation protection;

[0009] Multiple cable sleeves are spaced apart along the axial direction of the sector conductors. Each cable sleeve has a conductor cavity that matches the shape and torsion of the corresponding sector conductor. Each sector conductor is inserted into the corresponding conductor cavity for radial and circumferential limiting of the sector conductor.

[0010] Multiple sealant strips are respectively placed in the gap between two adjacent sector conductors and located between adjacent cable sleeves. The shape of the sealant strips is adapted to the gap between adjacent sector conductors and is used to laterally clamp adjacent sector conductors.

[0011] The filler layer, formed by curing the injected addition-type silicone rubber, fills the central gaps of multiple sector conductors, the gaps between the sector conductors and the outer insulating layer, and the gaps in the cable sheath, and is used to bond the sector conductors, cable sheath, sealant strip, and outer insulating layer into an integrated structure.

[0012] Preferably, the outer periphery of the cable sheath is provided with a plurality of spiral twisting grooves, the spiral direction of the twisting grooves being opposite to the twisting direction of the fan-shaped conductor. When the outer insulating layer is melt-coated, it is embedded in the twisting grooves to form an interlocking structure, which is used to suppress the relative slippage between the outer insulating layer and the cable sheath.

[0013] Preferably, multiple positioning slots are provided on both ends of the cable sleeve, and the silicone rubber of the filling layer is filled in the positioning slots to form an axial positioning structure to limit the axial displacement of the cable sleeve.

[0014] Preferably, the side wall of the cable sleeve is provided with multiple through slots, and the inner wall of the cable sleeve is provided with multiple transverse slots that connect to the corresponding through slots on the side facing the fan-shaped conductor. The silicone rubber of the filling layer is filled in the through slots and transverse slots to form a connector for reinforcing the constraint of the fan-shaped conductor.

[0015] Preferably, the outer edge region of the cable sleeve has multiple outer ring liquid inlet chambers, and the central region of the cable sleeve has an inner ring liquid inlet chamber. The injection pressure of the outer ring liquid inlet chambers is greater than that of the inner ring liquid inlet chambers, which is used to apply pressure to the outside of the sealant strip to ensure that the sealant strip is tightly attached to the fan-shaped conductor.

[0016] Preferably, the two wingtips of the fan-shaped conductor have a multi-level circular arc smooth transition structure without right angles or sharp corners. The side of the sealant strip near the fan-shaped conductor has an inner arc surface that is adapted to the circular arc transition structure, and the inner arc surface fits into the wingtips of the fan-shaped conductor.

[0017] Preferably, the sector-shaped conductor is formed by layered progressive compression molding with a compression coefficient of 0.88 to 0.92, which is used to release residual stress in the conductor forming process.

[0018] Preferably, the sealant strip includes a gap portion embedded in the gap between adjacent fan-shaped conductors, the gap portion extending outward to have a convex head that wraps around the side wings of the fan-shaped conductor, the inner arc surface being provided on the side of the convex head facing the fan-shaped conductor, and the side of the convex head away from the fan-shaped conductor being the outer pressure surface, and the sealant strip is made of a soft oxygen-free copper wire braided composite nitrile rubber conductive composite material.

[0019] Preferably, the viscosity of the addition-cured silicone rubber in the filler layer is 100 to 1000 cP during injection, the curing temperature is room temperature to 80 degrees Celsius, and the hardness after curing is Shore A20 to 60. The insulating outer layer is made of XLPE or PVC and is formed by extrusion.

[0020] The second objective of this invention is to provide a manufacturing process for a multi-core fan-shaped conductor compacted power cable, comprising the following steps:

[0021] S1. Processing of sector-shaped conductor: The copper rod is drawn into copper monofilament. The copper monofilament is layered and progressively compressed using a multi-stage combined compression die. The tips of the conductor on both sides are processed into a multi-stage rounded smooth transition structure. The compression coefficient is controlled between 0.88 and 0.92. The conductor is then cut to a preset length for later use.

[0022] S2. Pre-fabrication of sealant strip: The sealant strip is integrally molded using soft oxygen-free copper wire woven composite nitrile rubber conductive composite material to ensure that the inner arc surface of the sealant strip is compatible with the arc tip of the fan-shaped conductor.

[0023] S3. Pre-installation: Arrange multiple sector conductors in a twisted spiral posture, insert sealant strips into the gaps between adjacent sector conductors, and install cable sleeves at intervals along the axial direction of the sector conductors so that each sector conductor is inserted into the corresponding conductor cavity.

[0024] S4. Extrusion of the outer insulating layer: The pre-assembled cable core is fed into the extruder, and the molten insulating material is wrapped around the outer periphery of the cable core to form an outer insulating layer. The insulating material is embedded in the twisted groove on the outer periphery of the cable sheath and is water-cooled for shaping.

[0025] S5. Zoned Injection: Low-pressure injection equipment is used to inject addition-curing liquid silicone rubber into the cable core, and the output pressure of the outer ring liquid inlet cavity is controlled to be greater than that of the inner ring liquid inlet cavity, so that the silicone rubber fills all cavities and gaps.

[0026] S6. Low-temperature curing: Place the injected cable core in an environment of room temperature to 80 degrees Celsius for static curing. The finished product is obtained after the silicone rubber is completely cured.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. The embodiments of the present invention abandon the rough method of random filling in the traditional cabling process. First, high-precision prefabrication strips are made, and then the overall pre-assembly is completed in combination with cable sleeves. The inner arc surface of the sealant strip is precisely fitted with the arc tip of the conductor, forming a lateral clamping of adjacent fan-shaped conductors. The segmented cable sleeves are matched with suitable conductor cavities to limit the contour of a single conductor in the radial and circumferential directions. Multiple mechanical constraints work together to firmly lock the posture of multiple twisted spiral fan-shaped conductors, solving the common problem of the core easily flipping circumferentially and shifting radially when the traditional cable is cabled, dragged, or bent. The core position remains stable, which can suppress the mutual compression of conductors and prevent the filling material from being squeezed and slipped during the assembly process.

[0029] 2. In the embodiments of the present invention, positioning notches, straight grooves, and horizontal grooves are added to the cable sheath. After the injected silicone rubber is cured, it forms a positioning structure and an integrated connector, which further restricts the axial movement of the conductor and makes the internal structure of the cable core more tightly bonded. At the same time, a spiral twisted groove is set on the outer periphery of the cable sheath, which is opposite to the twisting direction of the conductor. When the outer insulation layer is extruded, the molten material is embedded in the groove to form a mechanical interlocking structure, which not only inhibits the relative slippage between the insulation layer and the internal components, but also seals the gaps between the layers. The entire combined structure eliminates the microscopic interface air gaps between the conductor, filler, and insulation. Combined with the hydrophobic properties of the addition-cured silicone rubber itself, it blocks the intrusion of external moisture and effectively inhibits the formation of water trees, solving the hidden dangers of insulation aging and moisture breakdown induced by air gaps in traditional cables.

[0030] 3. The embodiments of the present invention adopt a zoned differential pressure injection process, which utilizes the fluid pressure of the outer ring being greater than that of the inner ring to continuously compress the sealant strip, ensuring that it is always tightly attached to the conductor side wings. Low viscosity addition-type liquid silicone rubber is selected, which can smoothly fill all cavities and gaps of tens of meters of cable without problems such as incomplete filling or local voids. During the curing process, the rubber can chemically graft with metals and insulating materials, bonding the fan-shaped conductor, sealant strip, cable sheath, and outer insulating layer into an integrated whole, no longer the simple physical stacking structure of traditional cables. At the same time, after the silicone rubber is cured, it becomes an elastomer, which can deform synchronously with the bending and twisting of the cable, taking into account both the filling density and the adaptability of the cable core deformation, and greatly improving the overall structural strength.

[0031] 4. The embodiments of the present invention limit the curing temperature of silicone rubber to room temperature to 80°C, which is far lower than the melting point of XLPE insulation layer. Moreover, the curing of the rubber compound produces no by-products and will not damage the original components such as insulation layer and conductor throughout the process. This results in higher production safety and product yield. The entire structure combines the advantages of arc conductor, multiple limiting, dense filling, and waterproof sealing, which comprehensively solves a series of problems such as core misalignment, filling failure, partial discharge, and mechanical fatigue in traditional multi-core fan-shaped cables. The cable can still maintain structural integrity and stable electrical performance under complex working conditions such as thermal cycling, frequent bending, and field dragging. This effectively slows down the insulation aging rate, significantly extends the overall service life of the cable, reduces the probability of later maintenance failures in the power distribution system, and is suitable for use in various low-voltage power distribution scenarios such as buildings and factories.

[0032] 5. In the embodiments of the present invention, a multi-stage combined compression mold is used to progressively form the fan-shaped conductor in layers. The traditional right-angle wing tip is replaced with a smooth transition structure with large and small rounded arcs. At the same time, the compression coefficient is controlled at 0.88~0.92, which effectively releases the residual stress generated during the conductor forming process. Compared with the traditional right-angle fan-shaped conductor, this design eliminates the stress concentration point at the sharp corner, suppresses the cold work hardening phenomenon of the conductor filament, and significantly reduces the risk of single-filament fatigue and breakage under thermal expansion and contraction and mechanical vibration conditions. The rounded shape can also smooth the electric field distribution on the conductor surface, weaken the electric field distortion under low voltage conditions, and reduce the phenomenon of partial discharge. It solves the problem of electrical aging and mechanical damage caused by sharp corner defects in traditional fan-shaped conductors, laying the foundation for the long-term stable operation of the cable. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2 This is a schematic diagram of the half-section structure of the present invention;

[0035] Figure 3 For the present invention Figure 2 A schematic diagram of a half-section;

[0036] Figure 4 This is a schematic diagram of the connection structure between the cable sleeve and the sealant strip in this invention;

[0037] Figure 5 This is a schematic diagram of the separation structure between the cable sheath and the sector conductor in this invention;

[0038] Figure 6 For the present invention Figure 5 Enlarged schematic diagram of the structure at point A;

[0039] Figure 7 This is a schematic diagram of the arrangement structure of the sealant strip in this invention;

[0040] Figure 8This is a schematic diagram of the cable sleeve having a straight through groove and a horizontal through groove in this invention;

[0041] Figure 9 This is a schematic diagram of the connecting component in this invention;

[0042] Figure 10 This is a production process flow diagram of another embodiment of the present invention.

[0043] Explanation of the labels in the diagram:

[0044] 1. Sector-shaped conductor; 2. Central inner support bar; 3. Insulation outer layer; 4. Supplementary layer; 5. Cable sheath; 51. Conductor cavity; 52. Stranded groove; 53. Outer ring liquid inlet cavity; 54. Inner ring liquid inlet cavity; 55. Positioning notch; 6. Sealing strip; 601. Gap section; 602. Protruding head; 603. Inner arc surface; 604. Outer pressure surface; 71. Straight through groove; 72. Horizontal through groove; 73. Connecting component. Detailed Implementation

[0045] One of the objectives of the embodiments of the present invention relates to a multi-core sector conductor 1 compacted power cable, such as... Figures 1 to 9 As shown, the device includes multiple sector-shaped conductors 1 arranged in a twisted spiral array. A central inner support bar 2 is provided in the central region of each sector-shaped conductor 1. An insulating outer layer 3 is provided between the outer peripheries of each sector-shaped conductor 1. A supplementary layer 4 is provided in the gap between the insulating outer layer 3 and the sector-shaped conductors 1. The filling layer includes the central inner support bar 2 and the supplementary layer 4, which are made of the same material. The material of the central inner support bar 2 and the supplementary layer 4 is addition-cured liquid silicone rubber. During the curing process, its own active groups will chemically bond with the surfaces of the sector-shaped conductors 1, the cable sheath 5, and the insulating outer layer 3, thereby... The insulation layer forms a strong chemical bond. Multiple fan-shaped conductors 1 are installed with cable sleeves 5 at regular intervals. Multiple conductor cavities 51 adapted to the shape and twist of the fan-shaped conductors 1 are opened on the cable sleeves 5. The number of conductor cavities 51 corresponds to the number of fan-shaped conductors 1. Multiple sealant strips 6 are connected between adjacent cable sleeves 5. The sealant strips 6 are adapted to the gap between two adjacent fan-shaped conductors 1. The directional terms such as 'outer', 'inner', 'center', and 'edge' used in this article are all based on the radial cross section of the cable. The side closer to the cable axis is 'inner' or 'center', and the side farther from the cable axis is 'outer' or 'edge'.

[0046] Addition-cure liquid silicone rubber is injected as a liquid and subsequently cures. It has a low initial viscosity (100-1000 cP), allowing for easy injection into cables tens of meters long. After curing, its density is approximately 1.0-1.1 g / cm³, far lower than polyurethane (1.2-1.4), minimizing its impact on cable weight. It remains soft after curing, does not affect torsion, and has adjustable hardness (Shore A20-60). It retains its elastomer properties after curing, conforming to the cable's shape when bent. The curing process does not damage the insulation layer. The addition-cure curing (platinum catalyzed, no byproducts) allows for curing temperatures as low as room temperature or 60-80°C, far below the melting point of XLPE insulation (200°C), preventing insulation deformation. The curing process involves chemical grafting, resulting in excellent adhesion to PE / XLPE / metals, achieving strong bonding. Its dielectric constant is approximately 3.3-3.5, close to XLPE, and its dielectric strength is >20 kV / mm, making it suitable for power cables. Silicone rubber is inherently hydrophobic, preventing water treeing and extending cable life.

[0047] Working principle: Multiple sector conductors 1 are arranged in a twisted spiral array. A central inner support bar 2 is set at the center of the overall cable core to provide central support for the entire group of sector conductors 1 and initially constrain the relative positions of each conductor. Multiple sets of cable sleeves 5 are installed at intervals along the axial direction of the sector conductors 1. Conductor cavities 51 that match the shape and twist angle of the sector conductors 1 are opened inside the cable sleeves 5. Each sector conductor 1 is respectively inserted into the corresponding conductor cavity 51. Relying on the contour limiting effect of the conductor cavity 51, the circumferential rotation and radial displacement of a single sector conductor 1 are restricted.

[0048] A sealant strip 6 is installed at the gap between two adjacent sector conductors 1. The sealant strip 6 is precisely matched with the gap between the conductor cores, further filling the empty space between the conductor cores and forming a lateral clamping constraint on the adjacent sector conductors 1, suppressing the conductors from squeezing and misaligning with each other. Subsequently, addition-curing liquid silicone rubber is injected into the cable core to form the central inner support strip 2 and the supplementary layer 4 in sequence. After the material is cured, it can be firmly bonded to the surrounding structure, connecting the sector conductors 1, cable sleeve 5, and sealant strip 6 into an integrated structure. The entire structure, through the combination of fixed-point positioning of cable sleeve 5, external constraint of conductor cavity 51, and lateral clamping of sealant strip 6, continuously locks the relative posture and position of all sector conductors 1 during cable laying, dragging, bending deformation, and thermal expansion and contraction during operation, effectively suppressing problems such as circumferential flipping, radial displacement, and axial movement of sector conductors 1, and ensuring the long-term regularity and stability of the internal structure of the cable core.

[0049] Furthermore, the cable sleeve 5 relies solely on the cured supplementary layer 4 for positioning, resulting in weak stability. To enhance the positional stability of the cable sleeve 5, multiple twisted grooves 52 are provided on the outer periphery of the cable sleeve 5. The twisted grooves 52 are arranged in a spiral trajectory, with the spiral direction of the twisted grooves 52 opposite to the twisting direction of the fan-shaped conductor 1. The insulating outer layer 3 is extruded and coated between the outer peripheries of multiple cable sleeves 5. The molten insulating material of the insulating outer layer 3 will form an "interlocking" with the twisted grooves 52 on the outer periphery of the cable sleeve 5. After curing, the inner wall of the insulating outer layer 3 and the twisted grooves 52 on the outer edge of the cable sleeve 5 are integrated, inhibiting interlayer slippage or water seepage.

[0050] Working principle: The outer circumferential sidewall of the cable sleeve 5 is processed with a spiral-shaped twisted groove 52, and the spiral direction of the groove is opposite to the overall twisting direction of the sector conductor 1. When the outer insulating layer 3 is extruded and wrapped on the outside of the cable sleeve 5, the molten insulating material will fully fill the inside of the twisted groove 52. After the insulating material cools and solidifies, the inner wall of the outer insulating layer 3 and the cable sleeve 5 form a mechanical interlocking structure with the twisted groove 52, and the two are tightly bonded together. Since the spiral direction of the twisted groove 52 is opposite to the twisting direction of the sector conductor 1, when the sector conductor 1 is subjected to vibration, thermal expansion and contraction, bending external force and generates a torsional tendency, the reverse spiral interlocking structure can form a reverse resistance, effectively offsetting the conductor torsional stress and limiting the circumferential and axial relative slippage between the cable sleeve 5 and the outer insulating layer 3. At the same time, the insulating material embedded in the twisted groove 52 can seal the interlayer gaps and prevent external moisture from penetrating, thereby enhancing the overall positioning stability of the cable sleeve 5 and improving the overall sealing performance of the cable core.

[0051] Furthermore, to further enhance stability, multiple positioning slots 55 are provided on both ends of the cable sleeve 5. The cured supplementary layer 4 can fill the positioning slots 55 to achieve axial positioning and suppress axial displacement. At the same time, multiple straight grooves 71 are provided on the side wall of the cable sleeve 5, and multiple transverse grooves 72 are provided on the inner wall of the cable sleeve 5 in the direction of the sector conductor 1. During the injection process, the addition-cured liquid silicone rubber will enter the transverse grooves 72 and then contact and connect with the side wall of the sector conductor 1 to form a whole. After the straight grooves 71 and transverse grooves 72 are injected and cured, they form a connector 73, which further strengthens the constraint of the sector conductor 1.

[0052] Furthermore, the stress concentration and partial discharge problems caused by the right-angled sharp corner of the sector conductor 1 will indirectly induce and aggravate faults such as core flipping and interface air gaps. The residual stress at the conductor sharp corner is large and the single filament is prone to fatigue deformation, which will change the original shape and mating dimensions of the sector core, causing the overall cable core to be unbalanced. During cabling, thermal expansion and contraction, and laying and dragging, circumferential flipping and misalignment are more likely to occur. The misalignment of the core will squeeze the filling material, causing filling slippage, gaps and the formation of interface air gaps.

[0053] The two wingtips of the fan-shaped conductor 1 are designed with a multi-level continuous arc transition structure, which is smoothly connected by large arcs and small arcs. A large rounded corner arc transition structure can also be used without hard edges. The conductor as a whole is formed by graded molding and compaction. The conductor filaments are progressively compacted from the center to the outside to uniformly release residual molding stress and suppress local extrusion overload. The filler strip 6 includes a gap 601, which has the same gap as the two adjacent fan-shaped conductors 1. A protruding head 602 extends from the outside of the gap 601 and wraps around the side wings of the two adjacent fan-shaped conductors 1. The side of the protruding head 602 close to the fan-shaped conductor 1 has an inner arc surface 603, which is designed to fit the arc transition structure. The side of the protruding head 602 away from the fan-shaped conductor 1 has an outer pressure surface 604. The filler strip 6 is made of soft oxygen-free copper wire braided composite nitrile rubber conductive composite material, which has high elasticity.

[0054] The arc transition structure replaces right-angled sharp corners, eliminating stress concentration points geometrically and reducing micro-stress caused by conductor forming and thermal expansion and contraction. Layered compaction ensures uniform stress on the conductor filaments, suppressing work hardening at sharp corners. The sealant strip 6 fills the tiny gaps on the surface of the arc transition structure, smoothing the curvature of the conductor's outer surface, significantly reducing the electric field intensity in the sharp corner area, and suppressing partial discharge under low-voltage conditions. At the same time, the elasticity of the composite rubber absorbs the alternating stress generated by thermal cycling and mechanical vibration, preventing stress transmission to the conductor filaments and suppressing fatigue micro-cracks and filament breakage under long-term operation. The conductive composite material ensures the overall conductivity continuity of the conductor without increasing contact resistance or affecting the cable's current-carrying capacity.

[0055] Furthermore, to facilitate the integral molding of the supplementary layer 4 and the central inner support strip 2, the cable sleeve 5 has multiple outer ring liquid inlet chambers 53 at the edge of the supplementary layer 4 area, and an inner ring liquid inlet chamber 54 in the central area of ​​the cable sleeve 5. The injection pressure of the multiple outer ring liquid inlet chambers 53 is greater than that of the inner ring liquid inlet chambers 54, which is used to apply pressure to the outside of the sealant strip 6 to ensure that the sealant strip 6 is tightly attached to the sector conductor 1. When the supplementary layer 4 and the central inner support strip 2 are integrally molded, a closed end needs to be fitted onto one end of the outer insulating layer 3, and then the liquid addition-forming liquid silicon in the liquid state is... Rubber is conveyed, and the injection pressure in the area of ​​supplementary layer 4 is greater than that in the area of ​​central inner support strip 2 through pressure control. This will give pressure to the outer pressure surface 604. Combined with the fitting of the inner arc surface 603 with the side wing of the fan-shaped conductor 1, the positional stability of the filler strip 6 can be enhanced and the fit can be guaranteed during the molding process of central inner support strip 2 and supplementary layer 4. After the area is filled, the cured addition-cured liquid silicone rubber forms supplementary layer 4 and central inner support strip 2. The processing is simple. In order to avoid the outer insulating layer 3 from bulging during injection, a sizing tool can be added to the outer periphery of the outer insulating layer 3.

[0056] The second objective of this invention relates to a manufacturing process for a multi-core sector-shaped conductor 1 compacted power cable, such as... Figure 10 As shown, it includes the following steps:

[0057] S1, Processing of sector-shaped conductor 1;

[0058] The copper rod is drawn into uniform copper monofilaments using a wire drawing machine, and surface burrs and oxide scale are removed. A multi-stage combined compression mold is used to strand the copper monofilaments in layers and progressively compress them, processing the tips of the conductors into a multi-stage arc transition structure with large and small arcs smoothly connected, removing hard edges. The compression coefficient is controlled between 0.88 and 0.92, releasing residual stress from conductor forming in layers. The straightness of the formed fan-shaped conductor 1 is corrected, and it is cut into corresponding material segments according to the production length, and stored separately for later use.

[0059] S2. Prefabrication and inspection of sealant strip 6;

[0060] The soft oxygen-free copper wire is used to braid a composite nitrile rubber conductive material. The filler strip 6 is formed by extrusion and molding to ensure the dimensional accuracy of the gap 601, the protruding head 602, the inner arc surface 603, and the outer pressure surface 604. The curvature of the inner arc surface 603 is perfectly matched with the arc tip of the fan-shaped conductor 1.

[0061] S3, sector conductor 1 and sealant strip 6 are pre-installed;

[0062] Multiple formed sector conductors 1 are arranged in a twisted spiral posture to restore the cable form; a sealant strip 6 is embedded in the gap between every two groups of adjacent sector conductors 1, so that the gap 601 is inserted into the core gap and the inner arc surface 603 is tightly attached to the arc tip of the sector conductor 1, completing the lateral clamping pre-assembly and ensuring that the sealant strip 6 does not shift or loosen.

[0063] S4, cable sleeve 5-section assembly;

[0064] Along the axial direction of the sector conductor 1, cable sleeves 5 are sequentially installed at set intervals, so that each sector conductor 1 is inserted into an independent conductor cavity 51; ensuring that the conductor twist angle is adapted to the conductor cavity 51, and the end face of the cable sleeve 5 fits naturally without compression or skewing.

[0065] S5, 3 sets of insulating outer layer;

[0066] The entire multi-core conductor structure, serving as the "cable core," is directly fed into the extruder head. Molten XLPE or PVC insulation material is uniformly coated around the cable core through a combination of die core and die sleeve within the die head, forming a continuous insulation layer. The molten insulation material will "engage" with the twisted grooves 52 around the cable sleeve 5, and after solidification, the insulation layer and cable sleeve 5 are fused together. After extrusion, uniform water cooling and shaping are performed to ensure that the outer insulation layer 3 has a uniform thickness, a smooth surface, and no delamination or bubbles between layers.

[0067] S6, Addition-cured liquid silicone rubber zoned injection;

[0068] Addition-curing liquid silicone rubber with a viscosity of 100~1000cP is selected and equipped with a low-pressure injection device, which is connected to the outer ring liquid inlet cavity 53 and the inner ring liquid inlet cavity 54 of the cable sleeve 5 respectively. The output pressure of the outer ring liquid inlet cavity 53 is greater than that of the inner ring liquid inlet cavity 54. The pressure difference is used to form a uniform external pressure on the outer pressure surface 604 of the sealant strip 6, so that the inner arc surface 603 always presses the side of the fan-shaped conductor 1, improving the adhesion stability of the sealant strip 6. The liquid silicone rubber flows through the outer ring liquid inlet cavity 53 and the inner ring liquid inlet cavity 54 in sequence. Some of the rubber flows into the horizontal through groove 72 along the straight groove 71, fully wetting the inner wall of the cable sleeve 5 and the side wall of the fan-shaped conductor 1. After the entire cavity and gap are completely filled with rubber, the injection is stopped and the tooling is fixed during injection.

[0069] S7. Low-temperature static curing;

[0070] The entire infused cable core is placed in a room temperature or 60-80°C environment for static curing, with the curing temperature strictly below the melting point of XLPE insulation. During the curing process, the addition-type liquid silicone rubber undergoes a chemical grafting reaction, firmly bonding with the conductor, cable sheath 5, sealant strip 6, and outer insulation layer 3. Simultaneously, the central inner support strip 2 and supplementary layer 4 are formed, and the connecting parts 73 are cured inside the straight groove 71 and the horizontal groove 72. After the silicone rubber is completely cured and the hardness reaches Shore A 20-60, the sealing ends and the outer circumferential sizing fixtures are removed.

[0071] After passing inspection, the products are neatly rolled up, labeled, and classified for storage; non-conforming products are individually marked and reworked.

[0072] This process employs a multi-stage combined compression die to progressively compress copper monofilaments in layers, processing the conductor tips into a multi-stage rounded transition structure, thus eliminating the traditional right-angled sharp corners. At the same time, the compression coefficient is controlled between 0.88 and 0.92, releasing residual stress from conductor forming in layers. Compared with the traditional one-time extrusion forming of fan-shaped conductors, this process solves the problems of stress concentration at sharp corners and work hardening of monofilaments, reduces fatigue and wire breakage in the later stages, and also weakens electric field distortion at sharp corners, reducing the risk of partial discharge.

[0073] Separate prefabricated sealant strips are made, and their shape and curvature accuracy are strictly controlled to ensure that their inner arc surface is completely fitted with the arc surface of the fan-shaped conductor. Then, the conductor and sealant strip are pre-assembled according to the actual twisting posture of the cable, and the cable sleeve is assembled in sections. Unlike the rough operation of randomly filling ropes and simple sealant strips during traditional cabling, this process achieves precise fitting and pre-positioning of components, and suppresses core misalignment and filling offset from the assembly stage.

[0074] During the extrusion of the outer insulating layer, the molten insulating material is embedded in the reverse spiral twisted grooves on the outer circumference of the cable sheath. After cooling, a strong mechanical interlocking structure is formed. Utilizing the characteristic that the grooves twist in the opposite direction to the conductor, reverse torsional resistance is generated. Compared with the traditional smooth sheath / insulation structure, this significantly suppresses the circumferential and axial slippage between the insulation layer and internal components, while sealing the gaps between layers and improving the overall waterproof sealing capability. When the silicone rubber is cured, it can chemically bond with metals and insulating materials, and the overall structural integrity is far superior to the traditional physical stacking filling.

[0075] The embodiments disclosed in this invention are preferred embodiments, but are not limited thereto. Those skilled in the art can easily understand the spirit of this invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of this invention, they are all within the protection scope of this invention.

Claims

1. A multi-core sector-shaped conductor compacted power cable, characterized in that, include: Multiple twisted spiral fan-shaped conductors (1) are used to transmit electricity; An insulating outer layer (3) is wrapped around the outer periphery of multiple sector conductors (1) for insulation protection; Multiple cable sleeves (5) are spaced apart along the axial direction of the sector conductor (1). Each cable sleeve (5) has a conductor cavity (51) adapted to the shape and twist of the corresponding sector conductor (1). Each sector conductor (1) is inserted into the corresponding conductor cavity (51) to limit the sector conductor (1) radially and circumferentially. Multiple sealant strips (6) are respectively placed in the gap between two adjacent sector conductors (1) and located between adjacent cable sleeves (5). The shape of the sealant strips (6) is adapted to the gap between the adjacent sector conductors (1) and is used to laterally clamp the adjacent sector conductors (1). The filling layer, formed by curing the injected addition-cured silicone rubber, fills the central gap of multiple sector conductors (1), the gap between the sector conductors (1) and the outer insulating layer (3), and the gap of the cable sheath (5), and is used to bond the sector conductors (1), cable sheath (5), sealant strip (6), and outer insulating layer (3) into an integrated structure.

2. The multi-core sector-shaped conductor compacted power cable according to claim 1, characterized in that, The cable sleeve (5) has multiple spiral twisted grooves (52) on its outer periphery. The spiral direction of the twisted grooves (52) is opposite to the twisting direction of the fan-shaped conductor (1). When the insulating outer layer (3) is melted and covered, it is embedded in the twisted grooves (52) to form an interlocking structure, which is used to suppress the relative slippage between the insulating outer layer (3) and the cable sleeve (5).

3. A multi-core sector-shaped conductor compacted power cable according to claim 2, characterized in that, Multiple positioning slots (55) are provided on both ends of the cable sleeve (5). The silicone rubber of the filling layer is filled in the positioning slots (55) to form an axial positioning structure, which is used to limit the axial displacement of the cable sleeve (5).

4. A multi-core sector-shaped conductor compacted power cable according to claim 3, characterized in that, The cable sleeve (5) has multiple through grooves (71) through the side wall. The inner wall of the cable sleeve (5) has multiple horizontal grooves (72) that connect the corresponding through grooves (71) on the side facing the fan-shaped conductor (1). The silicone rubber of the filling layer is filled in the through grooves (71) and the horizontal grooves (72) to form a connector (73) to strengthen the constraint of the fan-shaped conductor (1).

5. A multi-core sector-shaped conductor compacted power cable according to claim 4, characterized in that, The outer edge of the cable sleeve (5) is provided with multiple outer ring liquid inlet chambers (53), and the center area of ​​the cable sleeve (5) is provided with an inner ring liquid inlet chamber (54). The injection pressure of the outer ring liquid inlet chamber (53) is greater than that of the inner ring liquid inlet chamber (54), which is used to apply pressure to the outside of the sealant strip (6) to ensure that the sealant strip (6) is tightly attached to the fan-shaped conductor (1).

6. A multi-core sector-shaped conductor compacted power cable according to claim 1, characterized in that, The two wingtips of the fan-shaped conductor (1) have a multi-level circular arc smooth transition structure without right angles or sharp corners. The sealant strip (6) has an inner arc surface (603) on the side near the fan-shaped conductor (1) that is adapted to the circular arc transition structure. The inner arc surface (603) is in contact with the wingtips of the fan-shaped conductor (1).

7. A multi-core sector-shaped conductor compacted power cable according to claim 6, characterized in that, The sector conductor (1) is formed by layered progressive compaction with a compaction coefficient of 0.88 to 0.92 to release residual stress from conductor forming.

8. A multi-core sector-shaped conductor compacted power cable according to claim 6, characterized in that, The sealant strip (6) includes a gap portion (601) embedded in the gap between adjacent fan-shaped conductors (1). The gap portion (601) extends outward to a convex head (602) that wraps around the side wings of the fan-shaped conductor (1). The inner arc surface (603) is located on the side of the convex head (602) facing the fan-shaped conductor (1). The side of the convex head (602) away from the fan-shaped conductor (1) is the outer pressure surface (604). The sealant strip (6) is made of soft oxygen-free copper wire braided composite nitrile rubber conductive composite material.

9. A multi-core sector-shaped conductor compacted power cable according to claim 1, characterized in that, The viscosity of the addition-curing silicone rubber of the filling layer is 100 to 1000 cP, the curing temperature is room temperature to 80 degrees Celsius, and the hardness after curing is Shore A20 to 60. The insulating outer layer (3) is made of XLPE or PVC and is formed by extrusion process.

10. A manufacturing process for a multi-core sector-shaped conductor compacted power cable, characterized in that, Includes the following steps: S1, Fan-shaped conductor (1) processing: The copper rod is drawn into copper single wire, and the copper single wire is layered and progressively compressed using a multi-level combined compression mold. The tips of the conductor on both sides are processed into a multi-level arc smooth transition structure. The compression coefficient is controlled between 0.88 and 0.

92. It is then cut to the preset length for later use. S2, Prefabrication of sealant strip (6): The sealant strip (6) is integrally molded using soft oxygen-free copper wire braided composite nitrile rubber conductive composite material to ensure that the inner arc surface (603) of the sealant strip (6) is compatible with the arc tip of the fan-shaped conductor (1). S3, Pre-installation: Arrange multiple sector conductors (1) in a twisted spiral posture, insert sealant strips (6) into the gaps between adjacent sector conductors (1), and install cable sleeves (5) at intervals along the axial direction of the sector conductors (1) so that each sector conductor (1) is inserted into the corresponding conductor cavity (51); S4, Insulation outer layer (3) extrusion: The pre-assembled cable core is fed into the extruder, and the molten insulation material covers the outer periphery of the cable core to form the insulation outer layer (3). The insulation material is embedded in the twisted groove (52) on the outer periphery of the cable sleeve (5) and water-cooled for shaping. S5. Zoned injection: Low-pressure injection equipment is used to inject addition-curing liquid silicone rubber into the cable core. The output pressure of the outer ring liquid inlet cavity (53) is controlled to be greater than that of the inner ring liquid inlet cavity (54), so that the silicone rubber fills all cavities and gaps. S6. Low-temperature curing: Place the injected cable core in an environment of room temperature to 80 degrees Celsius for static curing. The finished product is obtained after the silicone rubber is completely cured.

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