Air-blown optical cable and production process therefor
Patent Information
- Application Number
- PCT/CN2026/098369
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-25
- Filing Date
- 2026-05-21
- Publication Date
- 2026-10-01
Smart Images
Figure CN2026098369_01102026_PF_FP_ABST
Abstract
Description
An air-blown optical cable and its manufacturing process
[0001] This application claims priority to Chinese Patent Application No. 202510356508.3, filed on March 25, 2025, entitled "An air-blown optical cable and its manufacturing process", the entire contents of which are incorporated herein by reference. Technical Field
[0002] This invention relates to optical cable products, and more particularly to an air-blown optical cable and its manufacturing process. Background Technology
[0003] Air-blown fiber optic cable is a technology that uses compressed gas (usually air) to propel optical fibers or electrical cables through a conduit. This technology is primarily used for fiber optic or cable cabling, especially in locations where manual laying is difficult, such as long-distance underground ducts. Air-blown fiber optic cables offer advantages such as efficient cable laying, reduced damage, long-distance cable laying, reduced labor intensity, and high scalability, making them widely used in the telecommunications industry and other fields requiring long-distance cable laying, particularly in the construction of fiber optic networks.
[0004] However, in the existing technology, when the optical cable is blown into the external duct, the contact area between the outer sheath of the optical cable and the access duct is large, which greatly increases the friction and thus increases the difficulty of air-blown optical cable construction and laying.
[0005] However, after the sheath is extruded outside the optical cable core, the optical cable needs to be sized in a sizing mold. Therefore, while reducing the difficulty of air-blown optical cable construction and laying, it is necessary to ensure that the optical cable production process meets the requirements. Summary of the Invention
[0006] This invention overcomes the shortcomings of the prior art and provides an air-blown optical cable and its manufacturing process.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an air-blown optical cable, comprising a cable core and an outer sheath covering the cable core, wherein a protruding strip is provided on the outer wall of the outer sheath, the height direction of the protruding strip extends outward along the radial direction of the optical cable, the length direction of the protruding strip extends along the length direction of the air-blown optical cable, the protruding strip is spirally wrapped around the surface of the outer sheath, and the height of the protruding strip is set to 0.1-0.4mm.
[0008] More specifically, on any radial surface of the air-blown optical cable, the cross-section of the protrusion is arc-shaped or trapezoidal.
[0009] More specifically, the pitch of the spiral ribs is set to be less than or equal to 0.5m.
[0010] More specifically, α = a:b; 2.4 ≤ α ≤ 1;
[0011] Where a is the height of the convex strip; b is the width of the convex strip.
[0012] More specifically, the cable core includes a plurality of optical fibers and an adhesive portion that intermittently bonds the plurality of optical fibers in the axial direction.
[0013] More specifically, any adhesive portion on any optical fiber is a first reference adhesive portion, an adjacent adhesive portion on an optical fiber adjacent to the first reference adhesive portion is a second reference adhesive portion, and an adjacent adhesive portion on an optical fiber adjacent to the second reference adhesive portion is a third reference adhesive portion, and the first reference adhesive portion, the second reference adhesive portion, and the third reference adhesive portion are on the same straight line.
[0014] More specifically, two colored wires are provided outside the plurality of optical fibers, and the two colored wires are twisted in opposite directions to bundle the plurality of optical fibers into an optical fiber bundle.
[0015] More specifically, water-blocking yarn is provided inside the optical fiber bundle.
[0016] A manufacturing process for air-blown optical cables includes the following steps:
[0017] S1, which is provided with an optical fiber ribbon and a water-blocking yarn, and two colored threads are wrapped around the outside of the optical fiber ribbon and the water-blocking yarn to form an optical fiber bundle.
[0018] S2, which is equipped with several fiber bundles twisted together to form a cable core, and then enters the mold after the cable is formed.
[0019] S3, the mold rotates, the cable core is extruded into the mold to form an outer sheath, and the convex strips formed on the outer sheath spirally wrap around the outer sheath;
[0020] S4, after the outer sheath is cured, it enters the sizing mold for vacuum sizing.
[0021] More specifically, the inner diameter of the sizing die is 0.6-0.8 mm larger than the outer diameter of the air-blown optical cable, and the length of the sizing die is set to 200-400 mm.
[0022] More specifically, a plurality of pressure-drawing holes are provided on the sizing die, and the coverage of the pressure-drawing holes is greater than 50% of the sizing die.
[0023] An air-blown optical cable and its manufacturing process address the deficiencies in the prior art. This invention offers the following advantages: A raised strip is provided on the outer side of the outer sheath, reducing friction between the optical cable and the outer duct during installation. This allows for more efficient cable laying, reduced damage, longer cable laying distances, and reduced labor intensity during air-blown installation. Simultaneously, setting the height of the raised strip to 0.1-0.4mm ensures that when the optical cable is laid into the external duct, friction is reduced, ensuring the air-blowing effect and reducing laying difficulty. Furthermore, the cable can pass through the sizing die without rubbing against it. After subsequent vacuuming, the raised strip transforms into a groove, altering its original structure. Attached Figure Description
[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments;
[0025] Figure 1 is a cross-sectional view of the present invention with the protrusion set as an arc along the radial direction of the optical cable;
[0026] Figure 2 is a cross-sectional view of the present invention with the protrusions set as trapezoids, cut along the radial direction of the optical cable;
[0027] Figure 3 is a schematic diagram of the structure of the present invention, in which several optical fibers and adhesive parts are combined to form an optical fiber ribbon;
[0028] Figure 4 is a schematic diagram of the structure of the present invention, in which an optical fiber ribbon and a water-blocking yarn are bound together by colored thread to form an optical fiber bundle.
[0029] Figure 5 is a schematic cross-sectional view of the sizing die of the present invention along the axial direction;
[0030] Figure 6 is a radial cross-sectional view of the sizing die of the present invention;
[0031] Figure 7 is a flowchart of the optical cable manufacturing process of the present invention;
[0032] In the diagram: 1. Cable core; 11. Optical fiber; 12. Adhesive part; 13. Water-blocking yarn; 14. Colored thread; 15. Optical fiber ribbon; 16. Optical fiber bundle; 2. Water-blocking tape; 3. Outer sheath; 4. Reinforcing member; 5. Raised strip; 6. Sizing mold; 61. Pressure hole. Detailed Implementation
[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this invention. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0034] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention. The embodiments of this invention will now be described in detail with reference to the accompanying drawings.
[0035] It should be understood that the accompanying drawings are for illustrative purposes only.
[0036] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention and therefore only show the components relevant to the present invention.
[0037] An air-blown optical cable, as shown in Figures 1-4, includes a cable core 1 and an outer sheath 3 covering the cable core 1.
[0038] As shown in Figure 3, the cable core 1 includes a plurality of optical fibers 11 and adhesive portions 12 that intermittently bond the plurality of optical fibers 11 in the axial direction. Any adhesive portion 12 on any optical fiber 11 is a first reference adhesive portion, an adjacent adhesive portion 12 on an optical fiber 11 adjacent to the first reference adhesive portion is a second reference adhesive portion, and an adjacent adhesive portion 12 on an optical fiber 11 adjacent to the second reference adhesive portion is a third reference adhesive portion. The first reference adhesive portion, the second reference adhesive portion, and the third reference adhesive portion are on the same straight line. For example, three optical fibers 11 are arranged in sequence as the first optical fiber, the second optical fiber, and the third optical fiber. Each optical fiber 11 has three adhesive portions 12 arranged in sequence as the first adhesive portion, the second adhesive portion, and the third adhesive portion. The first adhesive portion on the second optical fiber is defined as the first reference adhesive portion. The optical fibers adjacent to the first reference adhesive portion are the first optical fiber and the third optical fiber. The adhesive portions adjacent to the first reference adhesive portion are the first adhesive portions of the first optical fiber and the first adhesive portions of the third optical fiber. The two first adhesive portions are the second reference adhesive portions. If there is a fourth optical fiber, the optical fiber adjacent to the second reference adhesive portion is the fourth optical fiber. The first adhesive portion adjacent to the second reference adhesive portion is the first adhesive portion of the fourth optical fiber. This first adhesive portion is the third reference adhesive portion. The first reference adhesive portion, the second reference adhesive portion, and the third reference adhesive portion are on the same straight line, that is, the first adhesive portions of the first optical fiber, the second optical fiber, the third optical fiber, and the fourth optical fiber are on the same straight line.
[0039] The high-precision dispensing technology used in fiber optic cable 11 ensures that the connecting lines of adjacent adhesive portions 12 of any adjacent fiber optic cable 11 are on the same straight line. In this design, the adhesive portions 12 are set as adhesive dots, with a deviation of less than 0.1mm between them. This high precision helps ensure that the cross-sectional differences between several fibers 11 after cutting are minimal during the overall fusion splicing process of fiber optic cable 11, maximizing the stability of fusion splicing performance and reducing fusion loss.
[0040] In this scheme, the bare optical fiber size is set between 230μm and 240μm. After the optical fiber 11 is colored, the size of the optical fiber 11 is between 235μm and 245μm. Then, a layer of resin is coated on the surface of the optical fiber 11, and the size of the optical fiber 11 after coating with resin is between 240μm and 250μm.
[0041] The adhesive length of fiber 11, D2, is 20±5mm, and the adhesive distance of fiber 11, D3, is 40±5mm. The tilted dimension, D4, is exactly D4 = D2 * (number of fibers 11 - 1). The overall width of the fiber bundle 16, D1, is equal to the resin-coated dimension of fiber 11 * N + (40~60μm), where 40~60μm is a correction factor, representing the tiny gaps directly existing in fiber 11, providing higher mobility and resistance to external forces. Compared to fiber ribbons 15 bonded with traditional adhesive dots, this method achieves the same strength with smaller adhesive dots; if the same dot size is used, even greater strength can be obtained.
[0042] The fiber optic ribbon 15, employing a dispensing structure, ensures a tight bond between the optical fibers 11 with minimal adhesive usage. Traditional fiber optic ribbons 15, using full resin coating, suffer from overall structural curing, leading to breakage during winding and thus occupying space within the optical cable. The fiber optic ribbon 15 disclosed in this solution can be wound into a single strand of optical fibers 11 or twisted in less than one revolution, significantly enhancing its flexibility, drastically reducing the space required, and providing a smaller bending radius.
[0043] As shown in Figure 4, two colored wires 14 are arranged around several optical fibers 11. The two colored wires 14 are twisted in opposite directions to bundle the optical fibers 11 into a bundle. The optical fibers 11 are then bonded to form an optical fiber ribbon 15. The two colored wires 14 can bundle only one optical fiber ribbon 15 or multiple optical fiber ribbons 15. One or more optical fiber ribbons 15 and a water-blocking yarn are combined and twisted by the two colored wires to form an optical fiber bundle 16. A water-blocking yarn 13 is placed inside the optical fiber bundle 16. The water-blocking yarn 13 is made of high-expansion water-blocking yarn. The colored wires 14 bundle one or more optical fiber ribbons 15 and a water-blocking yarn 13 to form an optical fiber bundle 16. Several optical fiber bundles 16 are twisted into a cable core 1. Prepare one or more optical fiber ribbons 15 and a high-expansion water-blocking yarn, and then prepare two colored wires 14. Wrap one or more optical fiber ribbons 15 and a water-blocking yarn 13 by twisting in opposite directions. The color thread 14 uses 111D polyester yarn, which can be designed in different colors according to requirements to facilitate the differentiation of different fiber bundles 16. Fiber ribbons 15 within any bundle can be distinguished by inkjet markings. Setting the pitch of the color thread 14 winding to less than 7cm allows for better direct differentiation of fiber bundles 16. Traditionally, fiber bundles 16 often only have surface markings on the fiber ribbons 15. However, when using markings as the primary identification method, it becomes difficult to quickly distinguish individual fiber bundles 16 as the core count increases. The different colored yarns in this solution allow construction personnel to quickly separate different fibers based on the color thread 14, significantly improving the splicing efficiency of ultra-high core count fiber bundles 16.
[0044] As shown in Figures 1 and 2, to reduce friction during air-blowing installation of the optical cable into the external duct, a raised strip 5 is provided on the outer wall of the outer sheath 3. The height of the raised strip 5 extends radially outward along the optical cable, and its length extends along the length of the air-blown optical cable. The height of the raised strip 5 is set to 0.1-0.4 mm, which is the distance from the outer sheath 3 to the highest point of the raised strip 5. To ensure air-blowing installation of the optical cable when entering the external duct, the raised strip 5 is spirally wrapped around the surface of the outer sheath 3. The pitch of the spiral raised strip 5 is set to be less than or equal to 0.5 m. When the pitch is greater than 0.5 m, the efficiency of air-blowing installation is poor. Furthermore, when the pitch of the spiral raised strip 5 is set to 0.01-0.5 m, there is only one raised strip 5 on any radial surface of the optical cable, resulting in better air-blowing effect.
[0045] Because the surface of the optical cable is relatively flat, there will be significant friction when laying the cable into external ducts, affecting the laying efficiency. Adding raised strips 5 to the surface of the outer sheath 3 can reduce friction with the external duct during laying. Different heights of the raised strips 5 can affect the air-blowing construction efficiency. Considering only the air-blowing effect, the height of the raised strips 5 needs to be set to 0.1-0.5mm to achieve a better air-blowing laying efficiency.
[0046] After the outer sheath 3 and the protruding strip 5 are extruded, they need to be sized by the sizing die 6. The sizing die 6 must have an inner diameter 0.6-0.8 mm larger than the outer diameter of the air-blown optical cable to ensure proper sizing. If the height of the protruding strip 5 is less than 0.05 mm, the vacuum pressure during passage through the sizing die 6 will flatten the protruding strip 5, resulting in the absence of the protruding strip 5 and thus failing to reduce friction. If the height of the protruding strip 5 exceeds 0.4 mm, the sizing die 6 will scrape against the protruding strip 5 during passage, causing the protruding strip 5 to become a groove after vacuuming, altering its original structure and failing to reduce friction. Therefore, to reduce friction, a protruding strip 5 can be provided on the outer sheath 3. However, to meet the requirements of the subsequent sizing process, the height of the protruding strip 5 needs to be maintained between 0.05-0.4 mm.
[0047] Therefore, considering both process requirements and air blowing effect, the height of the protrusion is set to 0.1-0.4mm in this solution.
[0048] On any radial surface of the air-blown optical cable, the shape of the protrusion 5 is arc-shaped or trapezoidal. When the cross-sectional shape of the protrusion 5 is set to trapezoidal, the size of the protrusion 5 is larger closer to the outer sheath 3 to ensure the air-blowing effect. The shape of the protrusion 5 is often arc-shaped or trapezoidal, but it can also be set to other shapes, as long as it can pass through the sizing die 6. However, setting it to other shapes may cause deformation and other problems. For example, a triangle, due to its pointed head, will cause scraping and indentation after entering the sizing die 6. If it is a square or rectangle, the angles on both sides are 90°, which is very easy to cause scraping, eventually causing the protrusion 5 to be flattened. At the same time, when the optical cable is laid to the external duct, the air-blowing effect is best when the shape of the protrusion 5 is arc-shaped or trapezoidal.
[0049] The height of the convex rib is the length of the line segment connecting the highest point of the convex rib to the surface of the outer sheath 3 and perpendicular to the tangent of the surface of the outer sheath 3; the width of the convex rib is the length of the line segment connecting the two ends of the widest part of the bottom edge of the convex rib. α = a:b; 2.4 ≤ α ≤ 1;
[0050] Where a is the height of the convex strip; b is the width of the convex strip; and α is the ratio of the convex strip height to the convex strip width.
[0051] Furthermore, the ratio of the height of the convex strip to the width of the convex strip is 2.4:1 to 1:1.
[0052] When the ratio of the height to the width of the convex strip is less than 1:1, that is, when the height of the convex strip is less than or greater than the width of the convex strip, the gas friction environment is poor when the optical cable is laid to the external pipeline. When the ratio of the height to the width of the convex strip is greater than 2.4:1, it will lead to a decrease in the strength of the tip of the convex strip, which will not only reduce the yield rate, but also directly affect the gain effect that the convex strip can bring to the optical cable. Therefore, when the ratio of the height to the width of the convex strip is controlled between 1 and 2.4, it can be ensured that the height and width of the convex strip are within the same arc length, so as to obtain a better gas friction environment as much as possible. That is, when the central angle is the same, the higher the surface convexity, the larger the specific surface area, while ensuring the structural strength.
[0053] A manufacturing process for an air-blown optical cable, as shown in Figures 5-7, includes the following steps:
[0054] S1, fiber 11 is laid out, several fiber 11 are arranged along the axial direction, and the adhesive part 12 connects several fiber 11 to form fiber optic ribbon 15. Two colored threads 14 are wrapped around the outside of one or several fiber optic ribbons 15 and a water-blocking yarn 13 to form fiber optic bundle 16.
[0055] S2, several bundles of optical fibers 16 are twisted together to form a cable core 1. After the cable is formed, it enters the mold. A water-blocking strip 2 is set on the outside of the cable core 1. The water-blocking strip 2 is set as an ultra-thin water-blocking strip 2.
[0056] S3, the motor drives the spiral head to rotate, which in turn drives the mold core to rotate. The cable core 1 is extruded into the outer sheath 3 in the mold. The outer sheath 3 is set on the water-blocking strip layer. The convex strips 5 formed on the outer sheath 3 are spirally wound on the outer sheath 3. The height of the convex strips 5 is set to 0.1-0.4mm. A reinforcing member 4 is set inside the outer sheath 3. The reinforcing member 4 is evenly distributed around the circumference of the outer sheath 3.
[0057] S4. After the outer sheath 3 is cured, it enters the sizing mold 6 for vacuum sizing. The optical cable is sizing in the sizing mold 6 to ensure the roundness of the optical cable.
[0058] As shown in Figures 5 and 6, the sizing die 6 is a device for sizing the optical cable after its fabrication. It is placed in water, and the cylinder of the sizing die 6 is made of a vacuum copper tube. The extruded optical cable passes through this tube to achieve sizing, ensuring its roundness. The overall length of the sizing die 6 is set to 200-400mm. If the length is less than 200mm, the sizing effect cannot be achieved; if the length is greater than 400mm, the sizing will be too long, causing the optical cable to constantly scrape against the surface of the sizing die 6, resulting in an unsatisfactory surface finish. The inner diameter of the sizing die 6 is 0.6-0.8mm larger than the outer diameter of the air-blown optical cable to ensure accurate sizing.
[0059] After the cable core 1 is extruded with the outer sheath 3 and the convex strip 5, the temperature will be relatively high. Therefore, the optical cable needs to be cooled after entering the sizing mold 6. In the usual setup, the sizing mold 6 is placed in water, and the water exchanges heat with the sizing mold 6 to cool the optical cable. However, the cooling effect of the sizing mold 6 on the optical cable is limited because only the sizing mold 6 is in contact with the external water. Therefore, several pressure-drawing holes 61 are opened on the sizing mold 6. The water placed outside the sizing mold 6 enters the interior of the sizing mold 6 through the pressure-drawing holes 61 and comes into contact with the high-temperature optical cable to better cool the optical cable. At the same time, vacuum pressure can be drawn inside the sizing mold 6. The size of the pressure-drawing holes 61 is set to 1.5mm, and the coverage of the pressure-drawing holes 61 is greater than 50% of the sizing mold 6.
[0060] A blown optical cable and its manufacturing process are disclosed. A raised strip 5 is provided on the outer side of the outer sheath 3 to reduce friction between the optical cable and the outer duct during installation, enabling more efficient cable laying, reducing damage, facilitating long-distance cable laying, and lowering labor intensity during blown installation. The height of the raised strip 5 is set to 0.1-0.4mm to ensure it can pass through the sizing die without rubbing against it. After subsequent vacuum evacuation, the raised strip 5 becomes a groove, altering its original structure. The raised strip 5 is also designed in a spiral shape for better blown installation. Vacuum sizing is performed within the sizing die 6 to ensure the roundness of the optical cable.
[0061] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
[0062] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0063] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
[0064] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.
Claims
1. A blown optical cable characterized by: It includes a cable core (1) and an outer sheath (3) covering the cable core (1). A protrusion (5) is provided on the outer wall of the outer sheath (3). The height direction of the protrusion (5) extends outward along the radial direction of the optical cable, and the length direction of the protrusion (5) extends along the length direction of the air-blown optical cable. The protrusion (5) is spirally wrapped around the surface of the outer sheath (3). The height of the protrusion (5) is set to 0.1-0.4mm.
2. The blown optical cable according to claim 1, characterized in that: On any radial surface of the air-blown optical cable, the cross-section of the protrusion (5) is arc-shaped or trapezoidal; when the cross-section of the protrusion (5) is set to trapezoidal, the closer it is to the outer sheath (3), the larger the cross-sectional size of the protrusion (5).
3. The blown optical cable according to claim 2, characterized by the fact that α = a : b; 2.4 ≤ α ≤ 1; Where a is the height of the convex strip; b is the width of the convex strip.
4. The blown optical cable of claim 1, wherein: The pitch of the spiral rib (5) is set to be less than or equal to 0.5m.
5. The blown optical cable of claim 1, wherein: The cable core (1) includes a plurality of optical fibers (11) and an adhesive portion (12) that intermittently bonds the plurality of optical fibers (11) in the axial direction.
6. The blown optical cable according to claim 5, characterized in that: Any adhesive portion on any optical fiber is a first reference adhesive portion, an adjacent adhesive portion on an optical fiber adjacent to the first reference adhesive portion is a second reference adhesive portion, and an adjacent adhesive portion on an optical fiber adjacent to the second reference adhesive portion is a third reference adhesive portion. The first reference adhesive portion, the second reference adhesive portion, and the third reference adhesive portion are on the same straight line.
7. The blown optical cable according to claim 5, characterized in that: Two colored wires (14) are provided outside the plurality of optical fibers (11), and the two colored wires (14) are wrapped in opposite directions to bundle the plurality of optical fibers (11) into an optical fiber bundle (16).
8. A process for the production of a blown optical cable, characterized in that: Including steps, S1, is provided with an optical fiber ribbon (15) and a water-blocking yarn (13), and two colored threads (14) are wrapped around the outside of the optical fiber ribbon (15) and the water-blocking yarn (13) to form an optical fiber bundle (16). S2, which is provided with several fiber bundles (16) twisted together to form a cable core (1), and then enters the mold after being cabled; S3, the mold rotates, and the cable core (1) is extruded into the outer sheath (3) in the mold. The protrusion (5) formed on the outer sheath (3) is spirally wound around the outer sheath (3). S4, after the outer sheath (3) is cured, it enters the sizing mold (6) for vacuum sizing.
9. The process for producing a blown optical cable according to claim 8, characterized in that: The inner diameter of the sizing die (6) is 0.6-0.8 mm larger than the outer diameter of the air-blown optical cable, and the length of the sizing die (6) is set to 200-400 mm.
10. The process for producing a blown optical cable according to claim 8, characterized in that: A plurality of pressure-drawing holes (61) are provided on the sizing die (6), and the coverage of the pressure-drawing holes (61) is greater than 50% of the sizing die (6).