Highly flame-retardant and pressure-resistant optical cable, forming die and forming process thereof
By integrating the inner and outer sheaths of the optical cable and filling the hollow layer with inorganic flame retardant, the problem of high fire temperature when optical cables are laid in the same trench is solved, achieving efficient flame retardancy and pressure resistance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HENGTONG OPTIC ELECTRIC CO LTD
- Filing Date
- 2023-09-18
- Publication Date
- 2026-06-09
AI Technical Summary
In existing technologies, when optical cables are laid in the same trench or trough, the fire temperature is high, and a single flame-retardant optical cable cannot effectively retard the fire, leading to serious consequences.
It adopts an integrated design of low-smoke halogen-free outer and inner sheaths, with an S-shaped bridge between the inner and outer sheaths. The hollow layer is filled with inorganic flame retardant, the optical fiber is wrapped by a loose tube and filled with water-blocking material, and the optical cable core is protected by fire-resistant tape.
It improves the flame retardant properties and compressive strength of the optical cable. The perforated layer quickly absorbs heat when damaged by flames, preventing the spread of flames and enhancing the overall fire resistance of the optical cable.
Smart Images
Figure CN117192710B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of optical fiber communication technology, and in particular to a high flame-retardant and pressure-resistant optical fiber cable, a forming mold, and a forming process thereof. Background Technology
[0002] Optical fiber cables are manufactured to meet optical, mechanical, or environmental performance specifications. They are communication optical cable assemblies that use one or more optical fibers encased in a protective sheath as the transmission medium and can be used individually or in groups. Optical fiber cables are mainly composed of optical fibers (glass filaments as thin as a hair), a plastic protective sheath, and a plastic outer jacket. They do not contain metals such as gold, silver, copper, or aluminum and generally have no recycling value. An optical fiber cable is a communication line that uses a certain number of optical fibers arranged in a specific way to form a cable core, encased in a sheath, and sometimes covered with an outer protective layer, to achieve the transmission of optical signals.
[0003] Currently, flame-retardant optical cables are being used more and more widely, especially in indoor or enclosed environments, where the requirements for flame retardancy of optical cables are becoming increasingly stringent.
[0004] However, current conventional flame-retardant optical cables can only meet the requirements for single-strand combustion. When large-scale optical cables are laid in the same trench or trough, if a fire occurs, the peak temperature can reach thousands of degrees. A single flame-retardant optical cable cannot play a flame-retardant role at all, and in severe cases, it can lead to extremely serious consequences. Summary of the Invention
[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the flame retardant effect is poor when laying large-scale optical cables at the same time, and that the flame retardant effect cannot be achieved at high temperatures in the prior art.
[0006] To solve the above-mentioned technical problems, the present invention provides a high flame-retardant and pressure-resistant optical cable, comprising: a low-smoke halogen-free outer sheath having a plurality of outer sheath perforated layers, wherein the outer sheath perforated layers are filled with an inorganic flame retardant; an inner sheath disposed inside the low-smoke halogen-free outer sheath, wherein the inner sheath has a plurality of inner sheath perforated layers, wherein the inner sheath perforated layers are filled with an inorganic flame retardant; and a plurality of inner and outer sheath bridging links, wherein one end of the inner and outer sheath bridging links is connected to the inner wall of the low-smoke halogen-free outer sheath, and the other end of the inner and outer sheath bridging links... The inner and outer sheaths are connected to the outer wall of the inner sheath, and several inner and outer sheaths are bridged at intervals, with a hollow buffer layer between adjacent inner and outer sheaths. The hollow buffer layer is located between the low-smoke halogen-free outer sheath and the inner sheath. A fire-resistant strip is set on the inner wall of the inner sheath, and several loose tube sleeves are provided inside the fire-resistant strip. Optical fibers are installed in the loose tube sleeves. The loose tube sleeves are arranged in a ring array, and a central reinforcing member is provided at the center of the circumference formed by the loose tube sleeves. The loose tube sleeves are filled with a water-blocking material. The high flame-retardant and pressure-resistant optical cable of the present invention achieves pressure resistance through the integrated inner and outer sheaths and the hollow layer. At the same time, the inner and outer sheaths have a hollow layer and are filled with inorganic flame retardant. After the sheath is damaged, the flame retardant can directly extinguish the flame, achieving a high flame-retardant effect.
[0007] In one embodiment of the present invention, both the low-smoke halogen-free outer sheath and the inner sheath are annular, and the low-smoke halogen-free outer sheath and the inner sheath are concentrically arranged, and the circumference of the plurality of loose tube sleeves is concentric with the low-smoke halogen-free outer sheath and the inner sheath.
[0008] In one embodiment of the present invention, the inner and outer bridging connections are arranged along the radial direction of the low-smoke halogen-free outer sheath and the inner sheath, and the radial cross-section of the inner and outer bridging connections is "S" shaped.
[0009] In one embodiment of the present invention, both the outer and inner perforated layers are arc-shaped, the outer perforated layer is arranged along the circumferential direction of the low-smoke halogen-free outer sheath, and the inner perforated layer is arranged along the circumferential direction of the inner sheath.
[0010] In one embodiment of the present invention, the loose sleeve is made of PBT.
[0011] In one embodiment of the present invention, the number of inner and outer protective bridges is 10, and the width of the inner and outer protective bridges is 0.5-0.7mm.
[0012] In one embodiment of the present invention, there are two outer sheath perforated layers and two inner sheath perforated layers, and the outer and inner sheath perforated layers surround the optical cable once.
[0013] In one embodiment of the present invention, the inorganic flame retardant is aluminum hydroxide flame retardant or magnesium hydroxide flame retardant.
[0014] In one embodiment of the present invention, a molding die for a high flame-retardant and pressure-resistant optical cable is provided. The low-smoke halogen-free outer sheath and inner sheath are integrally injection molded. The mold for the low-smoke halogen-free outer sheath and inner sheath includes an inner sheath molding part, an outer sheath molding part, and an intermediate bridging molding part. The inner sheath molding part, the outer sheath molding part, and the intermediate bridging molding part are all arranged in a ring shape, and the intermediate bridging molding part is disposed between the inner sheath molding part and the outer sheath molding part. The inner sheath molding part, the outer sheath molding part, and the intermediate bridging molding part are concentrically arranged. The center of the inner sheath molding part is provided with a circular through hole. The inner and outer diameters of the intermediate bridging molding part are provided with a plurality of S-shaped channels. The inner sheath molding part, the outer sheath molding part, and the S-shaped channels are hollow areas for filling with adhesive. The intermediate bridging molding part is a solid structure.
[0015] In one embodiment of the present invention, a forming process for a high flame-retardant and pressure-resistant optical cable includes the following steps:
[0016] S1. Fiber coloring: The fiber is colored according to a color spectrum to distinguish different fibers.
[0017] S2. Fiber coating: Coating the colored optical fibers with a certain quantity.
[0018] S3. Cable forming: Arrange the sheathed optical fibers in the color sequence, and twist them around the central reinforcing member in an SZ twisting pattern with a certain twisting pitch, and then fix them with binding yarn.
[0019] S4. Use water-blocking tape and fire-resistant tape to longitudinally wrap the cable core, and use a single water-blocking binding yarn to wrap and fix it.
[0020] S5. The low-smoke, halogen-free outer and inner sheaths are integrally molded using injection molding.
[0021] The technical solution of the present invention has the following advantages compared with the prior art:
[0022] This invention discloses a high flame-retardant and pressure-resistant optical cable, a forming mold, and its forming process. The optical cable core adopts a stranded or central tube structure, with water-blocking tape and mica fire-resistant tape sequentially wrapped around the outside of the core to improve the fire resistance of the optical cable. An S-shaped structure is used to bridge the inner and outer sheaths, which are integrally formed. Under high pressure, the S-shaped sheath can be compressed to resist external pressure, and the S-shaped bridge is restored when the external force is removed. Simultaneously, both the inner and outer sheaths contain perforated layers filled with inorganic flame retardants. Once the sheath is damaged by flame, the flame retardant in the perforated layers quickly absorbs heat upon contact with the flame, thereby preventing the flame from spreading further. Attached Figure Description
[0023] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...
[0024] Figure 1 This is a cross-sectional view of a first embodiment of a high flame-retardant and pressure-resistant optical cable according to the present invention;
[0025] Figure 2 This is a cross-sectional view of a second embodiment of a high flame-retardant and pressure-resistant optical cable according to the present invention;
[0026] Figure 3 This is a cross-sectional view of a molding die for a high flame-retardant and pressure-resistant optical cable according to the present invention.
[0027] Explanation of the reference numerals in the accompanying drawings: 1. Low-smoke halogen-free outer sheath; 2. Outer sheath perforated layer; 3. Inner sheath; 4. Inner and outer sheath bridging; 5. Hollow buffer layer; 6. Fire-resistant strip; 7. Loose tube sleeve; 8. Optical fiber; 9. Central reinforcement; 10. Water-blocking material for the sleeve; 11. Inner sheath forming part; 12. Outer sheath forming part; 13. Intermediate bridging forming part; 14. Circular through hole; 15. S-shaped channel; 16. Detailed Implementation
[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.
[0029] Reference Figure 1 , 2 As shown, a high flame-retardant and pressure-resistant optical cable of the present invention includes: a low-smoke halogen-free outer sheath 1, which has a plurality of outer sheath perforated layers 2, the perforated layers 2 being filled with an inorganic flame retardant; an inner sheath 3, which is disposed inside the low-smoke halogen-free outer sheath 1, and the inner sheath 3 has a plurality of inner sheath perforated layers 4, the perforated layers 4 being filled with an inorganic flame retardant; and inner and outer sheath bridging joints 5, which are configured in a plurality, one end of the inner and outer sheath bridging joints 5 being connected to the inner wall of the low-smoke halogen-free outer sheath 1, and the other end of the inner and outer sheath bridging joints 5 being connected to the outer wall of the inner sheath 3. The inner and outer protective bridges 5 are spaced apart, and a hollow buffer layer 6 is between adjacent inner and outer protective bridges 5. The hollow buffer layer 6 is located between the low-smoke halogen-free outer sheath 1 and the inner sheath 3. A fire-resistant strip 7 is set on the inner wall of the inner sheath 3. The fire-resistant strip 7 is provided with a number of loose tube sleeves 8. The loose tube sleeves 8 are provided with optical fibers 9. The number of loose tube sleeves 8 are arranged in a ring array, and a central reinforcing member 10 is provided at the center of the circumference formed by the number of loose tube sleeves 8. The loose tube sleeves 8 are filled with a sleeve water-blocking material 11.
[0030] This high flame-retardant and pressure-resistant optical cable features an integrated low-smoke halogen-free outer sheath 1 and inner sheath 3, with an S-shaped bridging structure between them to enhance the cable's pressure resistance. According to the above scheme, both the low-smoke halogen-free outer sheath 1 and inner sheath 3 have annular perforations filled with inorganic flame retardants to improve the cable's flame-retardant and fire-resistant properties.
[0031] Reference Figure 1 The diagram shows a loose fiber structure, where the optical fibers are isolated and have no physical connection; refer to... Figure 2 The image shows a cable structure, which refers to a ribbon-like structure formed by fixing a certain number of optical fibers together with resin.
[0032] In the above structure, both the low-smoke halogen-free outer sheath 1 and the inner sheath 3 are annular, and the low-smoke halogen-free outer sheath 1 and the inner sheath 3 are concentrically arranged. The circumference of the plurality of loose tube sleeves 8 is concentric with the low-smoke halogen-free outer sheath 1 and the inner sheath 3.
[0033] In the above structure, the inner and outer protective bridging joints 5 are arranged along the radial direction of the low-smoke halogen-free outer sheath 1 and the inner sheath 3, and the radial cross section of the inner and outer protective bridging joints 5 is "S" shaped.
[0034] In the above structure, both the outer perforated layer 2 and the inner perforated layer 4 are arc-shaped. The outer perforated layer 2 is arranged along the circumferential direction of the low-smoke halogen-free outer sheath 1, and the inner perforated layer 4 is arranged along the circumferential direction of the inner sheath 3.
[0035] In the above structure, the loose tube sleeve 8 is made of PBT and contains optical fiber (or optical fiber ribbon) and fiber grease to ensure the transmission and water-blocking performance of the optical fiber.
[0036] The cable core is covered by a dry water-blocking structure, using a combination of water-blocking tape and water-blocking yarn to protect the water-blocking performance of the optical cable core. Fire-resistant mica tape is used on the outside of the cable core to further protect the optical cable and improve its flame-retardant and fire-resistant properties.
[0037] In the above structure, there are 10 inner and outer protective bridges 5, and the width of the inner and outer protective bridges 5 is 0.5-0.7mm.
[0038] In the above structure, there are two outer sheath hollow layers 2 and two inner sheath hollow layers 4. The outer sheath hollow layers 2 and the inner sheath hollow layers 4 surround the optical cable once.
[0039] In the above structure, the inorganic flame retardant is aluminum hydroxide flame retardant or magnesium hydroxide flame retardant.
[0040] Reference Figure 3As shown, a molding die for a high flame-retardant and pressure-resistant optical cable is disclosed. The low-smoke halogen-free outer sheath 1 and inner sheath 3 are integrally injection molded. The mold for the low-smoke halogen-free outer sheath 1 and inner sheath 3 includes an inner sheath molding part 12, an outer sheath molding part 13, and an intermediate bridging molding part 14. The inner sheath molding part 12, the outer sheath molding part 13, and the intermediate bridging molding part 14 are all arranged in a ring shape, and the intermediate bridging molding part 14 is located between the inner sheath molding part 12 and the outer sheath molding part 13. The inner sheath molding part 12, the outer sheath molding part 13, and the intermediate bridging molding part 14 are concentrically arranged. The center of the inner sheath molding part 12 is provided with a circular through hole 15. Several S-shaped channels 16 are provided between the inner and outer diameters of the intermediate bridging molding part 14. The inner sheath molding part 12, the outer sheath molding part 13, and the S-shaped channels 16 are hollow areas used to fill adhesive. The intermediate bridging molding part 14 is a solid structure.
[0041] A forming process for a high flame-retardant and pressure-resistant optical cable includes the following steps:
[0042] S1. Fiber coloring: The fiber is colored according to a color spectrum to distinguish different fibers.
[0043] S2. Fiber coating: Coating the colored optical fibers with a certain quantity.
[0044] S3. Cable forming: Arrange the sheathed optical fibers in the color sequence, and twist them around the central reinforcing member in an SZ twisting pattern with a certain twisting pitch, and then fix them with binding yarn.
[0045] S4. Use water-blocking tape and fire-resistant tape to longitudinally wrap the cable core, and use a single water-blocking binding yarn to wrap and fix it.
[0046] S5. The low-smoke halogen-free outer sheath 1 and inner sheath 3 are integrally molded using injection molding.
[0047] The specific molding process mentioned above includes:
[0048] Step 1: Fiber coloring. The optical fibers are colored in the order of the color spectrum (blue, orange, green, brown, gray, white, red, black, yellow, purple, pink, cyan) to distinguish different optical fibers.
[0049] Step 2: Fiber Coating. Coat the colored optical fibers in a certain quantity. PBT material is recommended as the raw material for coating. When there are more than 12 optical fibers in the tube, color rings should be used to distinguish optical fibers of the same color. The colors of the tubes should also be arranged in the order of the color spectrum.
[0050] Step 3: Cable Assembly. The coated optical fibers are arranged according to their color sequence and twisted together in an SZ pattern around the central reinforcing member at a specific pitch, then secured with binding yarn. Next, water-blocking tape and fire-resistant tape are used to longitudinally wrap the cable core, and then secured with a single strand of water-blocking binding yarn.
[0051] Step 4: Integrated sheath molding. The single-layer extrusion mold needs to be changed to a double-layer integrated mold. The outer sheath is a low-smoke halogen-free sheath. The integrated sheath after extrusion has a hollow layer. During the extrusion process, an air blowing device is used to blow flame retardant into the hollow layer.
[0052] This invention relates to a high flame-retardant and pressure-resistant optical cable, comprising a loose tube 8 containing a water-blocking sheath; the loose tube 8 and filler rope (possibly included) are twisted together to form a layered or central tube type cable core, and the cable core is filled with a water-blocking sheath 11, with the cable core protected by a non-metallic fire-resistant tape; the low-smoke halogen-free outer sheath 1 and inner sheath 3 are integrally molded, and the low-smoke halogen-free outer sheath 1 and inner sheath 3 adopt an S-shaped structure for inner and outer sheath bridging 5, and the low-smoke halogen-free outer sheath 1 and inner sheath 3 also adopt a hollow design and are filled with flame retardant. This cable design meets the mechanical and environmental performance requirements of optical cables, while improving the flame-retardant and pressure-resistant performance of optical cables, providing design ideas for other types of optical cables. This cable has advantages such as ease of construction and maintenance, including its suitability for pipe racks, trenches, tunnels, fire resistance, self-extinguishing fire protection, and flame retardancy.
[0053] The innovation of this invention lies in:
[0054] First, structural innovation. Traditional flame-retardant optical cables typically rely on flame-retardant sheaths for flame retardancy. However, the upper limit of flame-retardant performance is currently limited by the base material of the optical cable sheath, making it difficult to meet the demands of increasingly stringent flame-retardant requirements in the future. In the optical cable structure of this invention, the inner and outer sheaths are integrally molded. The sheath contains a ring-shaped hollow structure filled with an inorganic flame retardant. Once the sheath is burned, the inorganic flame retardant can instantly absorb a large amount of heat, slowing down or even extinguishing the spread of flames along the optical cable. The S-shaped inner and outer sheath bridging structure further protects the optical cable and improves its overall compressive strength.
[0055] Secondly, technological innovation. The optical cable sheath adopts an integrated inner and outer sheath design with S-shaped bridging and annular perforation. This requires improvements to the optical cable mold, redesigning it from a traditional single-layer mold to a double-layer extrusion process. The S-shaped bridging should ideally consist of 10 segments, each approximately 0.5-0.7mm wide. The optical cable's compressive strength has been increased from 600N to 3000N. The central angle of the annular perforation is 90°, with a total of 4 annular perforations on both the inner and outer sheaths, ensuring the perforations completely encircle the optical cable. Because the inner and outer sheaths are integrally molded, production speed and cooling stages must be controlled. The production speed should be maintained at 15-25 m / min, and the cooling water should be set in three stages: the first stage cooling length should be no less than 3m with a water temperature between 60-70℃; the second stage cooling length should be no less than 5m with a water temperature between 40-50℃; and the third stage cooling length should be no less than 3m with a water temperature no lower than 25℃.
[0056] Third, material innovation. The flame retardancy of optical cables mainly relies on low-smoke halogen-free sheaths and inorganic flame retardants filled in the perforated layers. Aluminum hydroxide flame retardant is preferred; it is non-toxic and non-volatile. Under high flame temperatures, it generates aluminum oxide, absorbing a large amount of heat and simultaneously producing water vapor and absorbing surrounding oxygen, further reducing the flammability of the optical cable. Aluminum hydroxide flame retardants undergo a dehydration reaction between 245℃ and 320℃; therefore, the sheath extrusion temperature must be strictly controlled during production. If the sheath extrusion temperature exceeds 200℃, the flame retardant should be replaced with magnesium hydroxide flame retardant. The flame retardant principle of magnesium hydroxide is the same as that of aluminum hydroxide, but its reaction temperature is above 300℃, making it suitable for sheaths in higher temperature ranges.
[0057] Fourth, application innovation: the optical cable of this invention breaks through the single function of optical cables that only have communication, and is a new type of flame-retardant optical cable that integrates flame retardancy and pressure resistance.
[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A high flame-retardant and pressure-resistant optical cable, characterized in that, include: A low-smoke, halogen-free outer sheath has several perforated outer sheath layers, the perforated outer sheath layers being filled with an inorganic flame retardant. The inner sheath is located inside the low-smoke halogen-free outer sheath, and the inner sheath has several inner sheath perforated layers, the perforated layers of which are filled with inorganic flame retardant. The inner and outer protective bridges are configured in several ways. One end of the inner and outer protective bridges is connected to the inner wall of the low-smoke halogen-free outer sheath, and the other end of the inner and outer protective bridges is connected to the outer wall of the inner sheath. The inner and outer protective bridges are spaced apart, and a hollow buffer layer is between adjacent inner and outer protective bridges. The hollow buffer layer is located between the low-smoke halogen-free outer sheath and the inner sheath. A fire-resistant strip is installed on the inner wall of the inner sheath. The fire-resistant strip has several loose tube sleeves inside, and optical fibers are installed inside the loose tube sleeves. The loose tube sleeves are arranged in a ring array, and a central reinforcing member is provided at the center of the circumference formed by the loose tube sleeves. The loose tube sleeves are filled with a water-blocking material.
2. The high flame-retardant and pressure-resistant optical cable according to claim 1, characterized in that: Both the low-smoke halogen-free outer sheath and the inner sheath are circular, and the low-smoke halogen-free outer sheath and the inner sheath are concentrically arranged. The circumference of the plurality of loose tube sleeves is concentric with the low-smoke halogen-free outer sheath and the inner sheath.
3. The high flame-retardant and pressure-resistant optical cable according to claim 2, characterized in that: The inner and outer protective bridging is arranged along the radial direction of the low-smoke halogen-free outer sheath and the inner sheath, and the radial cross section of the inner and outer protective bridging is "S" shaped.
4. The high flame-retardant and pressure-resistant optical cable according to claim 2, characterized in that: Both the outer and inner perforated layers are arc-shaped. The outer perforated layer is arranged along the circumference of the low-smoke halogen-free outer sheath, and the inner perforated layer is arranged along the circumference of the inner sheath.
5. The high flame-retardant and pressure-resistant optical cable according to claim 1, characterized in that: The loose sleeve is made of PBT.
6. The high flame-retardant and pressure-resistant optical cable according to claim 1, characterized in that: The number of inner and outer protective bridges is 10, and the width of the inner and outer protective bridges is 0.5-0.7mm.
7. The high flame-retardant and pressure-resistant optical cable according to claim 1, characterized in that: The number of outer sheath perforated layers is 2, the number of inner sheath perforated layers is 2, and the outer sheath perforated layers and inner sheath perforated layers surround the optical cable once.
8. The high flame-retardant and pressure-resistant optical cable according to claim 1, characterized in that: The inorganic flame retardant is either aluminum hydroxide or magnesium hydroxide.
9. The molding die for a high flame-retardant and pressure-resistant optical cable according to claim 1, characterized in that: The low-smoke halogen-free outer sheath and inner sheath are integrally injection molded. The mold for the low-smoke halogen-free outer sheath and inner sheath includes an inner sheath molding part, an outer sheath molding part, and an intermediate bridging molding part. The inner sheath molding part, outer sheath molding part, and intermediate bridging molding part are all arranged in a ring shape, and the intermediate bridging molding part is located between the inner sheath molding part and the outer sheath molding part. The inner sheath molding part, outer sheath molding part, and intermediate bridging molding part are concentrically arranged. The center of the inner sheath molding part has a circular through hole. The inner and outer diameters of the intermediate bridging molding part have several S-shaped channels. The inner sheath molding part, outer sheath molding part, and S-shaped channels are hollow areas used to fill the adhesive. The intermediate bridging molding part is a solid structure.
10. The forming process of a high flame-retardant and pressure-resistant optical cable according to claim 1, characterized in that: Includes the following steps: S1. Fiber coloring: The fiber is colored according to a color spectrum to distinguish different fibers. S2. Fiber coating: Coating the colored optical fibers with a certain quantity. S3. Cable forming: Arrange the sheathed optical fibers in the color sequence, and twist them around the central reinforcing member in an SZ twisting pattern with a certain twisting pitch, and then fix them with binding yarn. S4. Use water-blocking tape and fire-resistant tape to longitudinally wrap the cable core, and use a single water-blocking binding yarn to wrap and fix it. S5. The low-smoke, halogen-free outer and inner sheaths are integrally molded using injection molding.