Bending-resistant optical cable adopting hollow-core optical fiber and production method of bending-resistant optical cable

Abstract

The invention provides an anti-bending optical cable adopting hollow-core optical fibers, the anti-bending optical cable comprises an elastic supporting framework, a flexible sealing layer and a flexible reinforcing sheath which are sequentially wrapped from inside to outside, the outer surface of the elastic supporting framework is provided with a plurality of grooves which are uniformly distributed and spirally arranged, and hollow-core optical fiber units are installed in at least part of the grooves; the hollow-core optical fiber unit comprises a hollow-core optical fiber and a sleeve wrapping the hollow-core optical fiber; the elastic supporting framework is made of a carbon fiber or aramid fiber material. The invention further provides a production method of the anti-bending optical cable adopting the hollow-core optical fiber. According to the anti-bending optical cable adopting the hollow-core optical fiber, through the collaborative design of flexible supporting and stress dispersion, the bending radius is reduced, hollow-core deformation in the bending process is avoided, and the adaptability of the hollow-core optical cable in a narrow space is improved.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and more specifically to a bend-resistant optical cable using hollow optical fiber and its manufacturing method. Background Technology

[0002] Hollow-core optical fiber has an air or vacuum core, and light is confined within the hollow core for transmission through a special cladding microstructure. Compared with traditional optical fibers, hollow-core optical fiber has advantages such as ultra-low latency, ultra-low loss, and greater capacity. Therefore, hollow-core optical fiber has excellent development and application prospects.

[0003] It is important to note that the hollow structure of hollow optical fibers results in relatively weak mechanical strength. Therefore, structures designed to improve mechanical performance are necessary during use. Existing optical cables using hollow fibers often employ rigid reinforcement structures to ensure mechanical performance, leading to a large bending radius (typically ≥30cm), making them unsuitable for the bending deployment requirements of confined spaces such as data center racks and building cabling. Furthermore, the rigid reinforcement structure is prone to localized stress concentration during bending, compressing the hollow fiber and causing it to collapse, resulting in a sharp increase in transmission loss or even transmission interruption. In addition, the internal structure of existing optical cables cannot achieve stress dispersion during bending, further exacerbating the impact of bending on transmission performance and limiting the application of hollow optical cables in confined spaces. Existing optical cables using hollow fibers are mostly stranded structures, which, due to the lack of a sealing structure, have a high probability of water seepage, and the presence of internal metal components can easily generate electromagnetic interference.

[0004] In summary, there is a need in this field to improve existing optical cables using hollow optical fibers in order to reduce the bending radius while ensuring the protection of the hollow optical fibers, and at the same time reduce the risk of water seepage and electromagnetic interference. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a bend-resistant optical cable using hollow optical fiber, which reduces the bending radius and avoids hollow deformation during bending by means of a synergistic design of flexible support and stress dispersion, thereby improving the adaptability of the hollow optical cable in confined spaces.

[0006] Another object of the present invention is to provide a method for producing the bending-resistant optical cable using hollow optical fiber.

[0007] To achieve the above objectives, the present invention provides a bend-resistant optical cable using hollow optical fibers, comprising an elastic support frame, a flexible sealing layer, and a flexible reinforcing sheath wrapped sequentially from the inside out. The outer surface of the elastic support frame has a plurality of uniformly distributed and spirally arranged grooves, and hollow optical fiber units are installed in at least some of the grooves. The hollow optical fiber unit includes a hollow optical fiber and a sleeve wrapped around the hollow optical fiber. The elastic support frame is made of carbon fiber or aramid fiber material.

[0008] Preferably, the hollow optical fiber is an anti-resonant hollow optical fiber.

[0009] Preferably, the hollow optical fiber is composed of a core, a cladding, and a coating layer wrapped sequentially from the inside out; the core has a diameter of 5.0 mm, and the cladding is composed of 6 uniformly distributed anti-resonant units.

[0010] Preferably, the flexible sealing layer is made of EFTE or PTFE material.

[0011] Preferably, the thickness of the flexible sealing layer is 1 mm.

[0012] Preferably, the gap between the inner wall of the flexible sealing layer and the groove forms an axial gas flow channel.

[0013] Preferably, the flexible reinforced sheath is made of flame-retardant PE material.

[0014] Preferably, the thickness of the flexible reinforced sheath is 1.5 mm.

[0015] This invention also provides a method for producing a bend-resistant optical cable using hollow optical fibers, wherein the elastic support skeleton is made of carbon fiber material and the flexible sealing layer is made of EFTE material, comprising the following steps:

[0016] (A) Sleeve preparation; Modified polyolefin particles are selected for the sleeve and dried to remove moisture from the material; The dried modified polyolefin particles are added to the extruder using an extrusion molding process, and the material is extruded through the extrusion die to form the sleeve. During the extrusion process, online detection equipment is used to monitor the outer diameter and wall thickness of the sleeve in real time to ensure that the dimensional accuracy meets the requirements. After the preparation is completed, the sleeve is tested for flexibility and wear resistance.

[0017] (B) Preparation of elastic support skeleton; High-strength carbon fiber filaments are selected for the elastic support skeleton and surface activation treatment is performed; The surface-activated carbon fiber filaments are woven into a spiral structure by a braiding machine. After preparation, the tensile strength of the support skeleton is tested to ensure that its tensile strength is ≥1500N. At the same time, the elastic recovery performance of the skeleton is tested, and the recovery rate after bending is required to be ≥98%; Simultaneously, the tensile strength of the carbon fiber filaments is tested, and carbon fiber filaments with tensile strength ≥2000MPa are selected for skeleton preparation.

[0018] (C) Preparation of flexible sealing layer: Using extrusion process, preheated EFTE resin particles are added to the extruder and the EFTE material is extruded on the outside of the support frame to form a flexible sealing layer. After preparation, the sealing layer is tested for sealing performance by immersion in water to ensure that there is no water leakage.

[0019] (D) Preparation of flexible reinforced sheath: Using extrusion process, flame-retardant PE granules with adjusted formula are added to the extruder, and flame-retardant PE material is extruded on the outside of the flexible sealing layer to form a flexible reinforced sheath. The roundness of the sheath is controlled during the extrusion process.

[0020] Preferably, in step (A), the extruder temperature is set to 160-180℃, the screw speed is 30-50 r / min, and the sleeve thickness is controlled at 0.8±0.05 mm; in step (B), the limiting die controls the screw pitch at 10-15 mm; in step (C), the extruder temperature is set to 200-220℃, the extrusion speed is 5-10 m / min, and a flexible sealing layer with a thickness of 1 mm±0.05 mm is formed; in step (D), the extruder temperature is set to 150-180℃, the extrusion speed is 3-8 m / min, and a flexible reinforcing sleeve with a thickness of 1.5±0.05 mm is formed.

[0021] Compared with existing technologies, the advantages of the hollow-core fiber-based anti-bending optical cable and its manufacturing method disclosed in this invention are as follows: The hollow-core fiber-based anti-bending optical cable, through the coordinated design of the sheath and support frame, can reduce the bending radius of the optical cable, thus adapting to the bending deployment requirements in confined spaces; the support frame of the hollow-core fiber-based anti-bending optical cable can disperse stress during bending, and the sheath can act as a buffer, avoiding direct pressure on the hollow-core optical cable, thereby effectively preventing hollow core collapse and ensuring the stability of optical cable transmission; the overall structure of the hollow-core fiber-based anti-bending optical cable has excellent flexibility and elastic recovery performance, while its tensile strength is ≥1500N, balancing deployment flexibility and mechanical reliability; the hollow-core fiber-based anti-bending optical cable ensures sealing performance through the EFET layer, effectively preventing moisture ingress; the overall structure of the hollow-core fiber-based anti-bending optical cable uses metal-free materials, enhancing anti-static interference capabilities and reducing electromagnetic interference and electrostatic conduction risks in densely wired areas such as computer rooms. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The figure shown is a cross-sectional view of a bend-resistant optical cable using hollow optical fiber according to this application.

[0024] Figure 2 The diagram shows a schematic of the limiting mold used in the production method of a bend-resistant optical cable using hollow optical fiber according to this application. Detailed Implementation

[0025] 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, and 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.

[0026] like Figure 1As shown, this application discloses a bend-resistant optical cable using hollow optical fibers, comprising, from the inside out, an elastic support frame 1, a flexible sealing layer 3, and a flexible reinforcing sheath 4. The outer surface of the elastic support frame 1 has several uniformly distributed and spirally arranged grooves 10, with hollow optical fiber units 2 installed in at least some of the grooves 10. Each hollow optical fiber unit 2 includes a hollow optical fiber 21 and a sleeve 22 wrapped around the hollow optical fiber 21. By employing the elastic support frame 1, the bending radius of the optical cable can be reduced, making it more suitable for deployment in confined spaces. During bending, the elastic support frame can distribute stress, preventing the hollow optical fiber from collapsing and ensuring stable transmission performance. The overall structure of the bend-resistant optical cable using hollow optical fibers exhibits excellent flexibility and elastic recovery performance, balancing deployment flexibility with reliable mechanical properties.

[0027] In addition to installing hollow fiber unit 2, the groove 10 can also be fitted with stranded sleeve or filler rope to form a composite cable to adapt to different application scenarios.

[0028] The outer surface of the elastic support frame 1 preferably has 6 evenly distributed and spirally arranged grooves 10, and the number of grooves can be changed to adapt to different application scenarios.

[0029] The elastic support frame 1 is preferably made of carbon fiber. Carbon fiber has excellent elastic recovery properties, enabling it to adapt to bending when the optical cable is bent, dispersing bending stress and avoiding localized stress concentration. It also improves the tensile strength of the optical cable, achieving a tensile strength ≥1500N. Alternatively, the elastic support frame 1 can be made of aramid fiber. Aramid fiber also possesses excellent strength and elastic recovery properties, with a tensile strength ≥1400N. It similarly achieves stress dispersion and improves the tensile strength of the optical cable, while also exhibiting good flexibility to meet the bending resistance requirements of the optical cable. Furthermore, because aramid fiber is less expensive than carbon fiber, it is more suitable for applications where material costs are a concern.

[0030] The hollow optical fiber 21 is preferably an anti-resonant hollow optical fiber, which consists of a core, a cladding, and a coating layer wrapped sequentially from the inside out. The core diameter is preferably 5.0 mm, and the cladding is preferably composed of 6 uniformly distributed anti-resonant units. The anti-resonant units are preferably made of low-modulus silicon material to improve the flexibility of the optical fiber body.

[0031] The flexible sealing layer 3 is preferably made of EFTE material and is extruded onto the outside of the elastic support frame 1. The thickness of the flexible sealing layer is preferably 1 mm. EFTE material has excellent flexibility and sealing properties, which can adapt to the elastic deformation of the elastic support frame 1 and prevent moisture intrusion. The gap between the inner wall of the flexible sealing layer 3 and the groove 10 can form an axial gas flow channel, ensuring the stability of the high-purity gas inside the hollow optical fiber 21.

[0032] The flexible sealing layer 3 can also be made of PTFE material. PTFE material has good sealing properties and flexibility, which can adapt to the elastic deformation of the supporting skeleton and prevent moisture intrusion. At the same time, it has the characteristics of high and low temperature resistance and corrosion resistance, and can be used in some special environments (such as high temperature and corrosive environments), thus expanding the applicable environment range of optical cables.

[0033] The flexible reinforced sheath 4 is made of flame-retardant PE material, with a preferred thickness of 1.5mm.

[0034] The aforementioned hollow-core fiber optic cable, devoid of any metal components, avoids electromagnetic interference and electrostatic conduction issues associated with metal parts, enhancing its anti-static interference capabilities and ensuring stable transmission in complex electromagnetic environments. Through the coordinated design of hollow-core fiber, sheathing, spiral elastic support frame, flexible sealing layer, and flexible reinforcing sheath, the cable's components work together to ensure flexibility and elastic recovery while also considering mechanical reliability, sealing performance, and flame retardancy, achieving optimization of multiple performance aspects.

[0035] This application also discloses a method for producing a bend-resistant optical cable using hollow-core optical fiber, wherein the elastic support skeleton is made of carbon fiber material and the flexible sealing layer is made of EFTE material, and the method includes the following steps:

[0036] (A) Sleeve preparation; Modified polyolefin granules are selected for the sleeve and dried in a drying oven at 80-100℃ for 4-6 hours to remove moisture from the material and prevent air bubbles from being generated during extrusion molding, which would affect the quality and performance of the sleeve; The dried modified polyolefin granules are added to the extruder using an extrusion molding process. The extruder temperature is set to 160-180℃ and the screw speed is set to 30-50 r / min. The material is extruded through the extrusion die to form the sleeve. The sleeve thickness is controlled at 0.8±0.05mm. During the extrusion process, online detection equipment is used to monitor the outer diameter and wall thickness of the sleeve in real time to ensure that the dimensional accuracy meets the requirements. After preparation, the sleeve is tested for flexibility and wear resistance.

[0037] (B) Preparation of the elastic support skeleton; the elastic support skeleton is made of high-strength carbon fiber filaments, which undergo surface activation treatment. The surface activity of the carbon fiber filaments is improved through plasma treatment, enhancing their bonding strength with other materials. The surface-activated carbon fiber filaments are then woven into a spiral structure using a braiding machine. Figure 2 The limiting mold shown controls the pitch at 10-15mm, maintaining uniform tension of the carbon fiber filaments during weaving to prevent loose strands and broken filaments. After preparation, the tensile strength of the support skeleton is tested to ensure that its tensile strength is ≥1500N. At the same time, the elastic recovery performance of the skeleton is tested, requiring a recovery rate of ≥98% after bending. Simultaneously, the tensile strength of the carbon fiber filaments is tested, and carbon fiber filaments with a tensile strength of ≥2000MPa are selected for skeleton preparation.

[0038] (C) Preparation of the flexible sealing layer: Using an extrusion process, preheated EFTE resin granules are added to an extruder. The extruder temperature is set to 200-220℃, and the extrusion speed is 5-10 m / min. The EFTE material is extruded onto the outside of the support frame to form a flexible sealing layer with a thickness of 1 mm ± 0.05 mm. During the extrusion process, it is ensured that the sealing layer is tightly fitted to the support frame without gaps, bubbles, or other defects. After preparation, the sealing layer is tested for airtightness using a water immersion method to ensure that there is no water leakage.

[0039] (D) Preparation of flexible reinforced sheath: Using extrusion process, flame-retardant PE granules with adjusted formula are added to the extruder. The extruder temperature is set to 150-180℃ and the extrusion speed is 3-8m / min. The flame-retardant PE material is extruded on the outside of the flexible sealing layer to form a flexible reinforced sheath with a thickness of 1.5±0.05mm. During the extrusion process, the roundness of the sheath is controlled to ensure that its outer diameter is uniform.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bend-resistant optical cable using hollow-core optical fiber, characterized in that, The device comprises an elastic support frame, a flexible sealing layer, and a flexible reinforcing sheath, which are wrapped sequentially from the inside out. The outer surface of the elastic support frame has several uniformly distributed and spirally arranged grooves, and hollow fiber units are installed in at least some of the grooves. The hollow fiber unit includes a hollow fiber and a sleeve wrapped around the hollow fiber. The elastic support frame is made of carbon fiber or aramid fiber material.

2. The bend-resistant optical cable using hollow optical fiber as described in claim 1, characterized in that, The hollow optical fiber is an anti-resonant hollow optical fiber.

3. The bend-resistant optical cable using hollow optical fiber as described in claim 2, characterized in that, The hollow optical fiber consists of a core, a cladding, and a coating layer, which are wrapped sequentially from the inside out. The core has a diameter of 5.0 mm, and the cladding consists of 6 uniformly distributed anti-resonant units.

4. The bend-resistant optical cable using hollow optical fiber as described in claim 1, characterized in that, The flexible sealing layer is made of EFTE or PTFE material.

5. The bend-resistant optical cable using hollow optical fiber as described in claim 4, characterized in that, The thickness of the flexible sealing layer is 1 mm.

6. The bend-resistant optical cable using hollow optical fiber as described in claim 4, characterized in that, The gap between the inner wall of the flexible sealing layer and the groove forms an axial gas flow channel.

7. The bend-resistant optical cable using hollow optical fiber as described in claim 1, characterized in that, The flexible reinforced sheath is made of flame-retardant PE material.

8. The bend-resistant optical cable using hollow optical fiber as described in claim 7, characterized in that, The thickness of the flexible reinforced sheath is 1.5 mm.

9. A method for producing a bend-resistant optical cable using hollow-core optical fiber, for producing the bend-resistant optical cable using hollow-core optical fiber as described in claim 1, wherein the elastic support skeleton is made of carbon fiber material and the flexible sealing layer is made of EFTE material, characterized in that... Including the following steps: (A) Sleeve preparation; Modified polyolefin particles are selected for the sleeve and dried to remove moisture from the material; The dried modified polyolefin particles are added to the extruder using an extrusion molding process, and the material is extruded through the extrusion die to form the sleeve. During the extrusion process, online detection equipment is used to monitor the outer diameter and wall thickness of the sleeve in real time to ensure that the dimensional accuracy meets the requirements. After the preparation is completed, the sleeve is tested for flexibility and wear resistance. (B) Preparation of elastic support skeleton; High-strength carbon fiber filaments are selected for the elastic support skeleton and surface activation treatment is performed; The surface-activated carbon fiber filaments are woven into a spiral structure by a braiding machine. After preparation, the tensile strength of the support skeleton is tested to ensure that its tensile strength is ≥1500N. At the same time, the elastic recovery performance of the skeleton is tested, and the recovery rate after bending is required to be ≥98%; Simultaneously, the tensile strength of the carbon fiber filaments is tested, and carbon fiber filaments with tensile strength ≥2000MPa are selected for skeleton preparation. (C) Preparation of flexible sealing layer: Using extrusion process, preheated EFTE resin particles are added to the extruder and the EFTE material is extruded on the outside of the support frame to form a flexible sealing layer. After preparation, the sealing layer is tested for sealing performance by immersion in water to ensure that there is no water leakage. (D) Preparation of flexible reinforced sheath: Using extrusion process, flame-retardant PE granules with adjusted formula are added to the extruder, and flame-retardant PE material is extruded on the outside of the flexible sealing layer to form a flexible reinforced sheath. The roundness of the sheath is controlled during the extrusion process.

10. The method for producing a bend-resistant optical cable using hollow optical fiber as described in claim 9, characterized in that, In step (A), the extruder temperature is set to 160-180℃, the screw speed is 30-50 r / min, and the sleeve thickness is controlled at 0.8±0.05mm; in step (B), the limiting die controls the screw pitch at 10-15mm; in step (C), the extruder temperature is set to 200-220℃, the extrusion speed is 5-10m / min, forming a flexible sealing layer with a thickness of 1mm±0.05mm; in step (D), the extruder temperature is set to 150-180℃, the extrusion speed is 3-8m / min, forming a flexible reinforcing sheath with a thickness of 1.5±0.05mm.

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