Bend-resistant power cable

Abstract

The utility model discloses a kind of bending-resistant power cable, including conductor, insulating layer, inner shielding layer, buffer layer, tensile layer, outer shielding layer and outer sheath layer by inside to outside in turn coaxially arranged;Shielding effectiveness and bending resistance are considered: outer shielding layer uses the composite structure of "semiconductive carbon fiber cloth (inside) +80-120 mesh copper mesh (outside)", and semiconductive carbon fiber cloth ensures the uniformity and flexibility of shielding, and copper mesh guarantees high shielding effectiveness (shielding attenuation amount is greater than or equal to 40dB), solve the contradiction of traditional single shielding layer "flexible then shielding weak, shielding strong then flexible poor";Meanwhile, 0.1mm-0.2mm hot melt adhesive bonding layer is arranged between outer shielding layer and tensile layer, further enhance interlayer bonding force, avoid shielding layer displacement when bending.

Description

Technical Field

[0001] This utility model relates to the field of power cable technology, and in particular to a bend-resistant power cable. Background Technology

[0002] In the field of power transmission, power cables, as the core carrier of electrical energy transmission, are widely used in various scenarios such as industrial equipment, construction engineering, mobile machinery, and new energy equipment. With the improvement of modern industrial automation and the increasing demand for equipment mobility, cables often need to withstand frequent bending operations in complex environments, such as power supply lines for robotic arms, drag chain cables for rail transit vehicles, temporary wiring in construction sites, and connection wires for portable electrical equipment. However, existing power cables have significant shortcomings in bending resistance, making them unsuitable for the high-frequency bending requirements of these scenarios. Specific problems are as follows: Insufficient conductor bending resistance: Existing cable conductors mostly use single-strand thick-diameter copper wire or low-strand stranded copper wire, which has poor flexibility. During frequent bending, the conductor is prone to breakage and oxidation due to stress concentration, leading to a decrease in cable conductivity and even causing open circuit faults. Especially in scenarios of repeated bending at small angles, the conductor's service life is usually less than 3,000 cycles (bending angle ±90°), which is difficult to meet the requirements for long-term use.

[0003] Weak buffering and tensile strength: When a cable is bent, radial compression and axial tensile stress are generated in the internal layers. Most existing cables do not have a dedicated buffering structure, or only use ordinary rubber filler, which cannot effectively absorb bending stress, making the insulation layer and shielding layer susceptible to compression damage. At the same time, the tensile layer is often made of low-strength fibers such as polyester and polypropylene, with a weaving density of less than 70%. During bending, tensile deformation can easily cause interlayer separation, further aggravating structural damage.

[0004] Insulation and shielding performance are prone to failure: The insulation layer of existing cables mostly uses ordinary polyethylene material, and the elongation at break is generally less than 200%. Cracks are easily formed when bent, which leads to a decrease in insulation performance and causes leakage risk. The inner and outer shielding layers mostly use single semi-conductive rubber or sparse copper mesh structure. The former has insufficient flexibility, and the latter is prone to mesh deformation when bent, which leads to a decrease in shielding effectiveness (the shielding attenuation decreases by 10-15dB). This makes it impossible to effectively suppress electromagnetic interference and affect the normal operation of precision equipment.

[0005] Poor durability of outer sheath: Existing cable outer sheaths are mostly made of PVC, ordinary rubber and other materials, which can withstand less than 30,000 bends (bending angle ±90°, bending rate 10 times / minute). Frequent bending can easily cause cracking and aging, resulting in the exposure of the internal shielding and insulation layers. This not only makes them susceptible to corrosion from external moisture and dust, but may also cause safety accidents due to mechanical damage, increasing equipment maintenance costs and downtime risks.

[0006] In summary, due to limitations in structural design and material selection, existing power cables suffer from problems such as short service life, poor performance stability, high maintenance costs, and significant safety hazards in high-frequency bending scenarios. They cannot meet the modern industrial demand for cables that are resistant to bending and highly reliable. There is an urgent need for a bending-resistant power cable that can balance flexibility, tensile strength, insulation shielding stability, and durability. Utility Model Content

[0007] In order to overcome the shortcomings of the existing technology, one of the objectives of this utility model is to provide a bending-resistant power cable.

[0008] One of the objectives of this utility model is achieved through the following technical solution: A bend-resistant power cable includes, from the inside out, a conductor, an insulation layer, an inner shielding layer, a buffer layer, a tensile layer, an outer shielding layer, and an outer sheath layer, arranged coaxially. The conductor is made of multiple strands of soft copper wire twisted together, and the gaps between the strands are filled with flexible insulating filler. The buffer layer is made of modified rubber material, and a number of spherical elastic protrusions are evenly distributed inside the buffer layer. The tensile layer is an aramid fiber braided layer with a braiding density of not less than 90%.

[0009] As a further improvement to the above technical solution: The diameter of each soft copper wire in the conductor is 0.1mm-0.3mm, and the stranding pitch of the soft copper wire is 8-12 times the outer diameter of the conductor; the flexible insulating filler is a silicone rubber filler with a Shore hardness of 30-40HA.

[0010] The insulating layer is made of flexurally resistant cross-linked polyethylene material with a thickness of 1.5mm-3mm and an elongation at break of not less than 300%; the inner shielding layer is a semi-conductive butyl rubber layer with a thickness of 0.3mm-0.8mm.

[0011] The diameter of the spherical elastic protrusions in the buffer layer is 0.5mm-1mm, and the distance between adjacent spherical elastic protrusions is 1mm-2mm; the spherical elastic protrusions have a hollow cavity inside, and the hollow cavity is filled with nitrogen gas.

[0012] The outer shielding layer is composed of a semi-conductive carbon fiber cloth and a copper mesh, wherein the semi-conductive carbon fiber cloth is located on the inner side and the copper mesh is located on the outer side, and the mesh count of the copper mesh is 80-120 mesh; an adhesive layer is also provided between the outer shielding layer and the tensile layer, the adhesive layer being a hot melt adhesive layer with a thickness of 0.1mm-0.2mm.

[0013] The outer sheath is made of thermoplastic polyurethane elastomer material with a thickness of 2mm-4mm, and the outer sheath can withstand bending cycles of no less than 100,000 times (bending angle ±90°, bending rate 10 times / minute). The outer surface of the outer sheath is also provided with several anti-slip ridges evenly distributed along the cable axis. The cross-section of the anti-slip ridges is semi-circular, and the height is 0.3mm-0.5mm.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. Significantly Improved Conductor Bending Life: The conductor uses multiple strands of soft copper wire with a diameter of 0.1mm-0.3mm (stretch pitch 8-12 times the conductor's outer diameter), and silicone rubber filler with a Shore hardness of 30-40HA fills the strand gaps, greatly improving the conductor's flexibility and resistance to deformation. Compared to existing single-strand thick-diameter conductors, the conductor of this invention has a breakage risk reduced by more than 80% in frequent bending scenarios of ±90°, and can support long-term bending use without affecting conductivity.

[0015] 2. Highly efficient buffering of bending stress, protecting the internal structure: The buffer layer is made of modified rubber material and contains spherical elastic protrusions with a diameter of 0.5mm-1mm and a spacing of 1mm-2mm (the hollow cavity inside the protrusion is filled with nitrogen). This structure can effectively absorb the radial compressive stress and impact load generated when the cable is bent through the elastic buffering effect of rubber deformation and nitrogen cavity, reducing mechanical damage to the insulation and shielding layers, so that the internal layers still maintain structural integrity after high-frequency bending, reducing the risk of insulation failure and shielding attenuation.

[0016] 3. Enhanced tensile strength and prevention of interlayer delamination: The tensile layer uses aramid fiber braiding with a braiding density of not less than 90%. The tensile strength of aramid fiber can reach 5-6 times that of steel wire, while also possessing good flexibility. This design can effectively resist the axial tensile force generated during cable bending, preventing interlayer delamination caused by tensile deformation, and also preventing the tensile layer itself from breaking during bending, further improving the overall structural stability of the cable.

[0017] 4. Balancing shielding effectiveness and bending resistance: The outer shielding layer adopts a composite structure of "semi-conductive carbon fiber cloth (inner side) + 80-120 mesh copper mesh (outer side)". The semi-conductive carbon fiber cloth ensures the uniformity and flexibility of the shielding, while the copper mesh ensures high shielding effectiveness (shielding attenuation ≥40dB), which solves the contradiction of "flexibility leads to weak shielding, and strong shielding leads to poor flexibility" in traditional single shielding layers. At the same time, a 0.1mm-0.2mm hot melt adhesive bonding layer is set between the outer shielding layer and the tensile layer to further enhance the interlayer bonding force and prevent the shielding layer from shifting when bent.

[0018] Extending the service life of the outer sheath and improving practicality: The outer sheath layer is made of thermoplastic polyurethane elastomer material (thickness 2mm-4mm), which can withstand bending cycles of no less than 100,000 times (±90°, 10 times / minute), which is 3-5 times that of the existing PVC sheath. It can effectively resist cracking and aging caused by long-term bending. In addition, the semi-circular anti-slip ridges (height 0.3mm-0.5mm) on the surface of the outer sheath not only facilitate the gripping and fixing of the cable during laying, but also reduce friction damage, further enhancing the practical value of the cable.

[0019] Adapting to diverse application scenarios and reducing overall costs: Through the aforementioned structural optimization, this invention enables the cable to possess excellent bending resistance, tensile strength, insulation, and shielding properties, making it widely applicable to high-frequency bending scenarios such as robotic arms, rail transportation, temporary construction, and portable equipment. Compared to existing cables, its service life is extended by 2-3 times, maintenance and replacement frequency is reduced, significantly decreasing equipment downtime and maintenance costs. It also reduces safety hazards caused by cable failures, demonstrating extremely high economic and practical value.

[0020] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this embodiment.

[0022] In the diagram: 1. Conductor; 2. Insulation layer; 3. Inner shielding layer; 4. Buffer layer; 5. Tensile layer; 6. Outer shielding layer; 7. Outer sheath layer; 8. Adhesive layer. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0024] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] The bend-resistant power cable provided in this embodiment is suitable for high-frequency bending power supply scenarios of industrial robotic arms (single bending angle of the robotic arm ±90°, with an average bending frequency of approximately 500 times per day). The overall outer diameter of the cable is 18mm, and the structure of each layer from the inside out is as follows: conductor 1, insulation layer 2, inner shielding layer 3, buffer layer 4, tensile layer 5, adhesive layer 8, outer shielding layer 6, and outer sheath layer 7. The parameters and manufacturing process of each component strictly follow the technical solution of the utility model, as detailed below: II. Specific parameters and manufacturing process of each component (a) Conductor 1 Materials and Structure: 99.99% pure soft copper wire is selected, with a single wire diameter set at 0.2mm (within the range of 0.1mm-0.3mm). 120 strands of soft copper wire are twisted together to form conductor 1 using a stranding process. The stranding pitch is controlled to be 10 times the outer diameter of conductor 1 (the outer diameter of conductor 1 is 6mm, so the stranding pitch is 60mm) to ensure the flexibility of the conductor.

[0027] Filling treatment: The gaps formed by the stranding of soft copper wires are filled with silicone rubber filler 11 with a Shore hardness of 35HA (meeting the requirements of 30-40HA). The filling process is extrusion filling process to ensure that the filler 11 is tightly attached to the soft copper wires without gaps, thereby improving the bending stress resistance of conductor 1.

[0028] (ii) Insulation layer 2 Material selection: Bend-resistant cross-linked polyethylene material (modified with 2% antioxidant and 1.5% toughening agent) is used, with an elongation at break of 320% (not less than 300%) and a volume resistivity ≥1×10¹. 6 Ω・cm.

[0029] Preparation process: Using an extruder, an insulation layer 2 is coated on the outer surface of conductor 1 at a melting temperature of 200℃ and a pressure of 1.2MPa. The coating thickness is set to 2mm (within the range of 1.5mm-3mm). After coating, it is subjected to a steam crosslinking treatment at 150℃ for 4 hours to enhance the bending resistance and mechanical strength of the insulation layer 2, ensuring that it does not crack when bent.

[0030] (iii) Inner shielding layer 3 Materials and parameters: Semi-conductive butyl rubber material (30% semi-conductive carbon black content) is selected, with a thickness of 0.5 mm (within the range of 0.3 mm to 0.8 mm), and the volume resistivity is controlled at 1 × 10⁻⁶. 4 -1×10 6 Ω・cm, meeting the shielding effectiveness requirements.

[0031] Coating process: A cold-feed extruder is used to extrude semi-conductive butyl rubber onto the outer surface of the insulation layer 2. The extrusion temperature is 120℃ and the linear speed is 10m / min to ensure that the inner shielding layer 3 is tightly bonded to the insulation layer 2 without delamination.

[0032] (iv) Buffer layer 4 Matrix material: EPDM rubber modified material (with 5% elastomer toughening agent added) is used to ensure that the matrix has good elasticity and aging resistance.

[0033] Spherical elastic protrusion design: During the preparation of buffer layer 4, uniformly distributed spherical elastic protrusions are formed inside it through mold injection molding. The diameter of the protrusion is set to 0.8mm (within the range of 0.5mm-1mm), and the distance between adjacent protrusions is 1.5mm (within the range of 1mm-2mm). A hollow cavity is reserved inside each spherical elastic protrusion. High-purity nitrogen (purity ≥99.9%) is filled into the hollow cavity through vacuum injection process at a filling pressure of 0.2MPa, so that the protrusion has excellent buffering and energy absorption effect.

[0034] Encapsulation method: The buffer layer 4 is encapsulated on the outer surface of the inner shielding layer 3 by extrusion process. The encapsulation thickness (including the height of the protrusion) is 3mm, ensuring that the protrusion and the buffer layer substrate are integrally formed without the risk of falling off.

[0035] (v) Tensile layer 5 Materials and weaving parameters: Aramid fiber (tensile strength ≥2800MPa) is selected, and a two-way weaving process (weaving angles of 45° in both the warp and weft directions) is used to form a tensile layer 5 on the outer surface of the buffer layer 4. The weaving density is set to 95% (not less than 90%) to ensure that the tensile layer 5 evenly covers the buffer layer 4 without any missing areas.

[0036] Process control: The linear speed during weaving is controlled at 8m / min, and the fiber tension is kept constant (50N) to avoid fiber stretching and deformation during weaving, and to ensure that the tensile strength of the tensile layer 5 is ≥1500N / 100mm.

[0037] (vi) Adhesive layer 8 Materials and parameters: Ethylene-vinyl acetate (EVA) hot melt adhesive is selected, with a thickness of 0.15mm (within the range of 0.1mm-0.2mm), a melting temperature of 110℃, and an adhesion strength ≥5N / 25mm.

[0038] Coating process: Hot melt adhesive is evenly coated on the outer surface of the tensile layer 5 using a hot melt adhesive coating machine. After coating, it is naturally cooled to room temperature to form an adhesive layer 8, ensuring that it is tightly bonded to the tensile layer 5 without bubbles or missing adhesive.

[0039] (vii) Outer shielding layer 6 Composite structure: The inner side uses semi-conductive carbon fiber cloth (surface resistance ≤100Ω / sq), and the outer side uses 100-mesh copper mesh (copper wire diameter 0.12mm, within the range of 80-120 mesh). The two are combined through a hot-pressing composite process. The hot-pressing temperature is 130℃ and the pressure is 0.8MPa, ensuring that the semi-conductive carbon fiber cloth and copper mesh are tightly bonded without delamination.

[0040] Wrapping process: The composite outer shielding layer 6 is wrapped around the outer surface of the adhesive layer 8 through a wrapping process with a wrapping overlap rate of 15%, ensuring that the outer shielding layer 6 completely covers the cable surface and the shielding attenuation is ≥40dB (in the 100MHz-1GHz frequency band).

[0041] (viii) Outer sheath layer 7 Material selection: Thermoplastic polyurethane elastomer (TPU, Shore hardness 85A) is used, and its bending resistance is tested to be 120,000 times (bending angle ±90°, bending rate 10 times / minute, not less than 100,000 times), and it has oil resistance and weather resistance (stable performance in environments from -40℃ to 80℃).

[0042] Preparation and Structure: The outer sheath layer 7 is covered on the outer surface of the outer shielding layer 6 by an extruder at a temperature of 180°C. The covering thickness is set to 3mm (within the range of 2mm-4mm). At the same time, during the extrusion process, anti-slip ridges are formed on the outer surface of the outer sheath layer 7 by a mold, which are evenly distributed along the cable axis. The cross-section of the ridges is semi-circular, the height is set to 0.4mm (within the range of 0.3mm-0.5mm), and the spacing between the ridges is 5mm. This improves the anti-slip performance during cable laying and avoids surface wear caused by dragging.

[0043] III. Assembly and Performance Testing of Examples Assembly process: Following the sequence of “Conductor 1 → Insulation layer 2 → Inner shielding layer 3 → Buffer layer 4 → Tensile layer 5 → Adhesive layer 8 → Outer shielding layer 6 → Outer sheath layer 7”, each layer is sequentially coated and laminated through a continuous production line. The production line speed is controlled at 6m / min to ensure that the coaxiality deviation of each layer is ≤0.1mm.

[0044] Performance testing: Specialized testing was conducted on the completed bend-resistant power cables, and the results are as follows: Bending resistance: After 120,000 consecutive bends at a bending angle of ±90° and a bending rate of 10 times / minute, the cable conductor 1 shows no breakage, the insulation layer 2 shows no cracks, and the outer sheath layer 7 shows no cracks. Electrical performance: AC withstand voltage (3kV, 1min) without breakdown, insulation resistance ≥500MΩ, outer shielding layer 6 shielding attenuation ≥40dB; Mechanical properties: tensile strength ≥1500N / 100mm, bending radius ≤15 times the outer diameter of the cable (meeting the requirements for laying in confined spaces for robotic arms).

[0045] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.

Claims

1. A bend-resistant power cable, characterized in that, It includes a conductor (1), an insulation layer (2), an inner shielding layer (3), a buffer layer (4), a tensile layer (5), an outer shielding layer (6), and an outer sheath layer (7) arranged coaxially from the inside to the outside; the conductor (1) is made of multiple strands of soft copper wire twisted together, and the gaps between the strands are filled with flexible insulating filler; the buffer layer (4) is made of modified rubber material, and several spherical elastic protrusions are evenly distributed inside the buffer layer (4); the tensile layer (5) is an aramid fiber braided layer with a braiding density of not less than 90%.

2. The bend-resistant power cable according to claim 1, characterized in that, The diameter of each soft copper wire in the conductor (1) is 0.1mm-0.3mm, and the twisting pitch of the soft copper wire is 8-12 times the outer diameter of the conductor (1); the flexible insulating filler is a silicone rubber filler with a Shore hardness of 30-40HA.

3. The bend-resistant power cable according to claim 1, characterized in that, The insulating layer (2) is made of flexurally resistant cross-linked polyethylene material with a thickness of 1.5mm-3mm and an elongation at break of not less than 300%; the inner shielding layer (3) is a semi-conductive butyl rubber layer with a thickness of 0.3mm-0.8mm.

4. The bend-resistant power cable according to claim 1, characterized in that, The diameter of the spherical elastic protrusion in the buffer layer (4) is 0.5mm-1mm, and the distance between adjacent spherical elastic protrusions is 1mm-2mm; the spherical elastic protrusion has a hollow cavity inside, and the hollow cavity is filled with nitrogen.

5. The bend-resistant power cable according to claim 1, characterized in that, The outer shielding layer (6) is composed of a semi-conductive carbon fiber cloth and a copper mesh, wherein the semi-conductive carbon fiber cloth is located on the inner side and the copper mesh is located on the outer side, and the mesh size of the copper mesh is 80-120 mesh; an adhesive layer (8) is also provided between the outer shielding layer (6) and the tensile layer (5), the adhesive layer (8) is a hot melt adhesive layer with a thickness of 0.1mm-0.2mm.

6. The bend-resistant power cable according to claim 1, characterized in that, The outer sheath layer (7) is made of thermoplastic polyurethane elastomer material with a thickness of 2mm-4mm. The outer sheath layer (7) has a bending resistance of not less than 100,000 times, a bending angle of ±90°, and a bending rate of 10 times / minute. The outer surface of the outer sheath layer (7) is also provided with several anti-slip ridges evenly distributed along the cable axis. The cross section of the anti-slip ridges is semi-circular, and the height is 0.3mm-0.5mm.

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