All-dry loose tube and manufacturing method, manufacturing equipment, optical cable thereof

Abstract

The application provides a full-dry loose tube and a manufacturing method, a manufacturing device and an optical cable thereof. The manufacturing device of the full-dry loose tube comprises a pay-off device, an optical unit electrostatic polarization device for electrostatically polarizing an optical unit entering the optical unit electrostatic polarization device, a coupling device for receiving the electrostatically polarized optical unit, a water-blocking powder electrostatic polarization device connected to the coupling device and sending the electrostatically polarized water-blocking powder into the coupling device to be coupled with the optical unit to form an optical fiber bundle, the polarity of the optical unit being opposite to that of the water-blocking powder, an extruder for receiving the optical fiber bundle and coating a plastic layer on the optical fiber bundle, a vacuum water tank arranged downstream of the extruder for rounding the optical fiber bundle coated with the plastic layer to form a loose tube, and a cooling water tank for cooling the rounded loose tube. The manufacturing device of the full-dry loose tube can realize active coupling of the optical unit and the water-blocking powder, ensure uniform distribution of the water-blocking powder and improve the rounding degree of the loose tube.

Description

Technical Field

[0001] This invention relates to the field of optical cable technology, and more specifically, to a fully dry loose tube, its manufacturing method, manufacturing equipment, and optical cable. Background Technology

[0002] Compared to traditional grease-filled optical cables, all-dry optical cables have the advantages of being lightweight, easy to splice, and clean and environmentally friendly, and are widely used in overseas markets.

[0003] Currently, in the structural design of all-dry optical cables, the water-blocking materials used in the loose tubes include water-blocking yarn and water-blocking powder. Because water-blocking powder has high requirements for the filling process, it is easy to encounter technical difficulties such as uneven dispersion, mold clogging, and affecting the tube size during production. Therefore, most all-dry optical cables use water-blocking yarn inside the loose tubes for water blocking.

[0004] When filling loose tubes of optical cables with water-blocking yarn, the yarn's material properties make it prone to irregular tangling with the optical fiber. This leads to excessive excess yarn and fiber length due to localized accumulation, which then adheres to the inner wall of the loose tube. Simultaneously, the yarn compresses the fiber, affecting its attenuation. In actual production, to avoid this risk, a larger loose tube size is required to ensure sufficient internal space, which is detrimental to controlling the outer diameter and cost. Using water-blocking powder instead of water-blocking yarn can reduce the negative impact on the optical fiber, increase core density, and allow the cable to operate over a wider range of ambient temperatures. However, during the filling process, current processes cannot achieve effective coupling between the water-blocking powder and the optical unit, resulting in uneven distribution, mold clogging, and even powder shedding, affecting the water-blocking performance and production efficiency of the loose tube. Summary of the Invention

[0005] The main objective of this invention is to provide a fully dry loose tube and its manufacturing method, manufacturing equipment, and optical cable, which can realize the active coupling of optical units and water-blocking powder, ensure the uniform distribution of water-blocking powder, and improve the roundness of the loose tube.

[0006] To achieve the above objectives, according to one aspect of the present invention, an apparatus for manufacturing fully dry loose-sleeve tubing is provided, comprising:

[0007] Paying-out device;

[0008] The optical unit electrostatic polarization device is located downstream of the wire feeding device and electrostatically polarizes the optical units entering the optical unit electrostatic polarization device.

[0009] The coupling device is located downstream of the electrostatic polarization device of the optical unit and receives the optical unit after it has been electrostatically polarized by the electrostatic polarization device of the optical unit.

[0010] The water-blocking powder electrostatic polarization device is connected to the coupling device, and the electrostatically polarized water-blocking powder is fed into the coupling device to couple with the optical unit to form an optical fiber bundle. The polarity of the optical unit is opposite to that of the water-blocking powder.

[0011] An extruder receives a bundle of optical fibers and coats the bundle with a plastic layer.

[0012] A vacuum water tank, located downstream of the extruder, is used to round the fiber bundles coated with plastic to form loose tubes.

[0013] The cooling water tank is used to cool the rounded loose sleeve.

[0014] Furthermore, the manufacturing equipment also includes a gas filling device, which is located upstream of the extruder and injects gas at a preset pressure into the plastic layer when the extruder coats the optical fiber bundle with a plastic layer.

[0015] Furthermore, the coupling device includes a coupling box, which includes an optical unit inlet mold, an optical unit outlet mold, and a water-blocking powder inlet mold. The optical unit inlet mold has multiple inlet mold holes, through which multiple optical units enter the coupling device. The optical unit outlet mold is located on the opposite side of the optical unit inlet mold and has one outlet mold hole. The water-blocking powder inlet mold is located on the upper side of the coupling device and is connected to the spray gun of the water-blocking powder electrostatic polarization device.

[0016] Furthermore, the centers of the multiple inlet holes of the optical unit inlet module are located on the same circle, which is coaxially arranged with the outlet hole, and the optical unit inlet module can rotate relative to the central axis of the outlet hole.

[0017] Furthermore, the optical unit inlet module has a detachable structure.

[0018] Furthermore, the coupling device also includes a vibrating screen and a water-blocking powder recovery device. The bottom of the coupling box is open, the vibrating screen is located at the bottom of the coupling box, and the water-blocking powder recovery device is located below the vibrating screen.

[0019] Furthermore, the water-blocking powder recovery device includes a heating device, a conduit, and a pneumatic device. The conduit is connected to a storage container for storing electrostatically polarized water-blocking powder, the heating device is used to heat the water-blocking powder recovered in the water-blocking powder recovery device, and the pneumatic device is used to suck the water-blocking powder into the storage container.

[0020] According to another aspect of the present invention, a method for manufacturing a fully dry loose sleeve is provided, using the aforementioned manufacturing equipment, comprising:

[0021] Optical unit line feeding;

[0022] The optical unit after the wire is laid is electrostatically polarized;

[0023] Add water-blocking powder with opposite polarity to the electrostatically polarized optical unit, so that the optical unit and the water-blocking powder are coupled to form an optical fiber bundle.

[0024] The fiber bundle is extruded to form a loose tube.

[0025] The loose tubing is shaped, cooled, and wound up.

[0026] Further, the step of extruding the fiber bundle and forming the extruded fiber bundle into a loose tube includes:

[0027] During the extrusion process, gas is introduced into the plastic layer, making the inside of the plastic layer hollow and forming a loose tube;

[0028] The loose sleeve is inserted into a vacuum water tank, and the roundness of the loose sleeve is adjusted using the vacuum water tank.

[0029] Furthermore, the step of adding electrostatically polarized water-blocking powder with opposite polarity to the electrostatically polarized optical unit, and coupling the optical unit and the water-blocking powder to form an optical fiber bundle, includes:

[0030] Multiple optical units are controlled to twist and twist together, and water-blocking powder is added during the twisting and twisting process. The water-blocking powder is sprayed from above the water-blocking powder inlet mold downwards through the spray gun of the water-blocking powder electrostatic polarization device.

[0031] According to another aspect of the present invention, a loose tube is provided, which applies the above-described manufacturing method. The loose tube includes a plastic layer, a water-blocking powder, and an optical unit. The water-blocking powder is wrapped around the optical unit to form an optical fiber bundle. The plastic layer is covered over the optical fiber bundle. The plastic layer includes an inner surface, which includes a rounded surface and a concave surface.

[0032] Furthermore, the concave surface occupies 10% to 25% of the arc on the inner surface of the plastic layer.

[0033] Furthermore, the radius of curvature of the concave surface is less than or equal to half the thickness of the plastic layer at its location; and / or, the curvature of the concave surface ranges from 0 to π.

[0034] Furthermore, the concave surface is a rough surface.

[0035] Furthermore, the plastic layer is filled with at least one anti-shrinkage membrane that extends continuously along the axial direction of the loose sleeve, and the anti-shrinkage membrane is arc-shaped in the cross-section of the loose sleeve.

[0036] Furthermore, the anti-shrinkage film has a longitudinal shrinkage rate of ≤0.2% at 250℃~300℃, a thickness of 0.5mm~0.2mm, and a width of 0.5mm~5mm.

[0037] Furthermore, the outer diameter of the loose sleeve ranges from 0.8mm to 20mm, and the wall thickness ranges from 0.08mm to 1mm. When the outer diameter of the loose sleeve is less than or equal to 5.0mm, the plastic layer material is one of PBT, PP, TPEE, and PC; when the outer diameter of the loose sleeve is greater than 5.0mm, the plastic layer material is one of TPEE, PE, and PP.

[0038] According to another aspect of the present invention, an optical cable is provided, comprising a cable core made of the aforementioned loose tube and an outer sheath covering the cable core.

[0039] According to the technical solution of this invention, the manufacturing equipment for a fully dry loose tube includes: a wire feeding device; an optical unit electrostatic polarization device, located downstream of the wire feeding device, for electrostatic polarization of the optical units entering the optical unit electrostatic polarization device; a coupling device, located downstream of the optical unit electrostatic polarization device, for receiving the optical units electrostatically polarized by the optical unit electrostatic polarization device; a water-blocking powder electrostatic polarization device, connected to the coupling device, for feeding the electrostatically polarized water-blocking powder into the coupling device to couple with the optical units to form an optical fiber bundle, wherein the polarity of the optical units is opposite to the polarity of the water-blocking powder; an extruder, for receiving the optical fiber bundle and coating the optical fiber bundle with a plastic layer; a vacuum water tank, located downstream of the extruder, for rounding the plastic-coated optical fiber bundle to form a loose tube; and a cooling water tank for cooling the rounded loose tube. The manufacturing equipment for this fully dry loose tube uses a coupling device and electrostatic adsorption principle to couple the water-blocking powder and the optical unit, realizing the active coupling between the optical unit and the water-blocking powder. This allows the water-blocking powder to be uniformly and stably adsorbed on the surface of the optical unit, improving the uniformity of the water-blocking powder distribution. A vacuum water tank is used to adjust the roundness of the loose tube, which can effectively solve the roundness adjustment requirements of large-sized loose tubes, realize the rapid shaping of the loose tube, and improve the roundness of the loose tube. Attached Figure Description

[0040] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0041] Figure 1 A structural diagram of a manufacturing apparatus for a fully dry loose-sleeve pipe according to an embodiment of the present invention is shown;

[0042] Figure 2 A perspective structural diagram of the coupling device of a fully dry loose-sleeve pipe manufacturing apparatus according to an embodiment of the present invention is shown; and

[0043] Figure 3 A schematic diagram of the structure of a fully dry loose sleeve according to an embodiment of the present invention is shown.

[0044] The above figures include the following reference numerals:

[0045] 1. Wire feeding device; 2. Optical unit; 3. Optical unit electrostatic polarization device; 4. Water-blocking powder electrostatic polarization device; 5. Coupling device; 51. Optical unit inlet mold; 52. Optical unit outlet mold; 53. Water-blocking powder inlet mold; 54. Vibrating screen; 55. Water-blocking powder recovery device; 6. Gas filling device; 7. Extruder; 8. Vacuum water tank; 9. Cooling water tank; 10. Drying device; 11. Diameter gauge; 12. Traction device; 13. Wire take-up device; 14. Outer surface; 15. Inner surface; 16. Anti-shrinkage film; 17. Water-blocking powder; 18. Concave surface. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] See also Figures 1 to 3 As shown, according to an embodiment of the present invention, the manufacturing equipment for a fully dry loose tube includes: a wire feeding device 1; an optical unit electrostatic polarization device 3, located downstream of the wire feeding device 1, for electrostatic polarization of the optical unit 2 entering the optical unit electrostatic polarization device 3; a coupling device 5, located downstream of the optical unit electrostatic polarization device 3, for receiving the optical unit 2 after electrostatic polarization by the optical unit electrostatic polarization device 3; a water-blocking powder electrostatic polarization device 4, connected to the coupling device 5, for feeding the electrostatically polarized water-blocking powder 17 into the coupling device 5 to couple with the optical unit 2 to form an optical fiber bundle, wherein the polarity of the optical unit 2 is opposite to the polarity of the water-blocking powder 17; an extruder 7, for receiving the optical fiber bundle and coating the optical fiber bundle with a plastic layer; a vacuum water tank 8, located downstream of the extruder 7, for rounding the plastic-coated optical fiber bundle to form a loose tube; and a cooling water tank 9 for cooling the rounded loose tube.

[0048] The manufacturing equipment for the fully dry loose tube uses a coupling device 5 and the principle of electrostatic adsorption to couple the water-blocking powder 17 and the optical unit 2, realizing the active coupling between the optical unit 2 and the water-blocking powder 17. This allows the water-blocking powder 17 to be uniformly and stably adsorbed on the surface of the optical unit 2, improving the uniformity of the distribution of the water-blocking powder 17. A vacuum water tank 8 is used to adjust the roundness of the loose tube, which can effectively solve the roundness adjustment requirements of large-sized loose tubes, realize the rapid shaping of the loose tube, and improve the roundness of the loose tube.

[0049] Generally, during the forming process of loose tubes, there are requirements on the diameter of the loose tube to ensure its roundness. When the outer diameter of the loose tube is ≤5.0mm, a high degree of roundness can be achieved by controlling the gas filling pressure and gas flow rate, and the vacuum water tank 8 is not required in this case. When the outer diameter of the loose tube is ≥5.0mm, the extrusion flow rate is large, and the gas flow rate required for forming is also larger. When the loose tube enters the water tank, the air blowing pressure is insufficient to support the entire loose tube, causing the loose tube to sag due to its own plastic weight, resulting in an elliptical shape and adhesion between the optical fiber and the inner wall of the loose tube. Therefore, a vacuum water tank 8 is required. By controlling the vacuum degree within the vacuum water tank 8, a pressure difference is created between the inside and outside of the loose tube, providing support for the plastic layer, thereby accelerating the shaping process and improving the roundness of large-sized loose tubes. With the addition of the vacuum water tank 8, the preparation of fully dry loose tubes with outer diameters ranging from 0.8mm to 20mm can be effectively met.

[0050] In one embodiment, the manufacturing equipment further includes a gas filling device 6, which is located upstream of the extruder 7 and injects gas at a preset pressure into the plastic layer when the extruder 7 coats the optical fiber bundle with a plastic layer.

[0051] In this embodiment, by providing a gas filling device 6, the plastic layer can be inflated when the fiber bundle is coated with a plastic layer in the extruder, so that the plastic layer is shaped into a loose tube with a hollow interior and a high degree of roundness on the outside.

[0052] The gas filling device 6 and the vacuum water tank 8 can work together and be used simultaneously to reduce the fluctuation of the outer diameter of the loose tube and improve the roundness of the shaped appearance of the loose tube. The vacuum water tank 8 includes components such as a vacuum pump, a vacuum sizing box, a vacuum gauge, an exhaust valve, a water adjusting valve, and a sizing copper tube.

[0053] In one embodiment, the cooling water tank 9 has multiple temperature gradients. The temperature gradients gradually decrease along the direction of the fiber bundle. The cooling water in different temperature gradients circulates and flows, which can select the appropriate temperature of cooling water for cooling according to the temperature change of the loose tube at different positions, thereby improving the cooling effect on the loose tube and reducing the back shrinkage of the loose tube during the cooling process, especially for large-sized loose tubes.

[0054] In one embodiment, the cooling water tank 9 has three temperature gradients: 35°C, 25°C, and 15°C. Each temperature gradient includes a double-layered water tank, within which cooling water circulates. The circulation of cooling water at each temperature gradient through the upper and lower double-layered water tanks improves the flow efficiency of the cooling water at each temperature gradient, enhances the heat exchange efficiency between the cooling water and the loose-sleeve pipe, and improves the cooling effect of the cooling water on the loose-sleeve pipe.

[0055] In one embodiment, the coupling device 5 includes a coupling box, which comprises an optical unit inlet mold 51, an optical unit outlet mold 52, and a water-blocking powder inlet mold 53. The optical unit inlet mold 51 has multiple inlet mold holes through which multiple optical units 2 enter the coupling device 5. The optical unit outlet mold 52 is located on the opposite side of the optical unit inlet mold 51 and has one outlet mold hole. The water-blocking powder inlet mold 53 is located on the upper side of the coupling device 5 and is connected to the spray gun of the water-blocking powder electrostatic polarization device 4. A cavity is formed inside the coupling box for the optical units 2 to pass through and couple with the water-blocking powder 17.

[0056] The optical unit inlet module 51 has multiple inlet holes, which facilitates the optical unit 2 entering the coupling device 5 to form an optical fiber bundle; each inlet hole has a smooth ceramic eye, and the ceramic eye can be matched with a suitable inner diameter according to the size of the optical unit; the inner diameter of the ceramic eye = the equivalent diameter of the optical unit + (0.5~1.5) mm; the multiple inlet holes are arranged circumferentially and evenly.

[0057] In one embodiment, the centers of the multiple inlet mold holes of the optical unit inlet mold 51 are located on the same circle, which is coaxially arranged with the outlet mold hole, and the optical unit inlet mold 51 is rotatable relative to the central axis of the outlet mold hole.

[0058] In one embodiment, the optical unit inlet module 51 is a detachable structure.

[0059] The optical unit inlet module 51 is detachably assembled on the coupling box of the coupling device 5. The number of holes on the optical unit inlet module 51 is not fixed, ranging from 1 to 48. Multiple optical unit inlet modules 51 can be manufactured to facilitate the installation of appropriate optical unit inlet modules 51 during each production run, ensuring that the number of holes matches the number of optical units 2. Simultaneously, the optical unit inlet module 51 can be horizontally twisted (0° to ±180°) via a power device. This horizontal twisting action serves two purposes: first, it enables excess length control; second, it ensures that each optical unit 2 is dispersed into the coupling device 5, increasing the contact area with the water-blocking powder 17 during stranding. In particular, the internal space of the fiber bundle can be twisted to allow the optical unit 2 to contact the water-blocking powder 17, which is more conducive to coupling with the water-blocking powder 17.

[0060] In one embodiment, the optical unit exit module 52 and the optical unit inlet module 51 are symmetrically placed on the other side of the coupling device 5; the optical unit exit module 52 has only one exit module hole, and the central axis of the exit module hole and the multiple inlet module holes of the optical unit inlet module 51 are on the same horizontal plane; a smooth ceramic eye is installed on the exit module hole, and the inner diameter of the ceramic eye is equal to the equivalent diameter of the multiple optical units of the fiber bundle + (0.5~1.5) mm.

[0061] Depending on the type of optical unit, the ceramic eye can be round or square; the ceramic eye should not be too large to prevent powder from overflowing; nor should it be too small to avoid scratching or clogging the optical unit.

[0062] In one embodiment, the water-blocking powder inlet mold 53 is located above the coupling device 5 and connected to the spray gun of the water-blocking powder electrostatic polarization device 4, so that the water-blocking powder 17 is sprayed from top to bottom; the size and shape of the water-blocking powder inlet mold 53 are matched with the spray gun.

[0063] To ensure the effectiveness of the water-blocking powder spraying, the shape of the water-blocking powder inlet mold 53 can be circular, linear, or a dot array, depending on the number and type of optical units.

[0064] In one embodiment, the coupling device 5 further includes a vibrating screen 54 and a water-blocking powder recovery device 55. The bottom of the coupling box is open, the vibrating screen 54 is located at the bottom of the coupling box, and the water-blocking powder recovery device 55 is located below the vibrating screen 54.

[0065] The vibrating screen 54 is located below the coupling space to prevent excess, non-adhesive water-blocking powder from accumulating at the bottom of the coupling space. Through mechanical vibration, excess water-blocking powder is directed into the water-blocking powder recovery device 55. The vibrating screen 54 has sensors that can detect the weight of the accumulated water-blocking powder, thereby automatically starting the vibrating screen and controlling the vibration frequency.

[0066] In one embodiment, the water-blocking powder recovery device 55 includes a heating device, a conduit, and a pneumatic device. The conduit is connected to a storage container for storing electrostatically polarized water-blocking powder 17. The heating device is used to heat the water-blocking powder 17 recovered in the water-blocking powder recovery device 55. The pneumatic device is used to suck the water-blocking powder 17 into the storage container.

[0067] The water-blocking powder recovery device 55 is used to store the recovered water-blocking powder 17. The device includes an infrared heating device for drying the water-blocking powder 17. The device is connected to the storage container of the electrostatically polarized water-blocking powder 17 via a conduit and is equipped with a pneumatic device to enable the recycling and reuse of the water-blocking powder. The device also contains a sensor; when the water-blocking powder accumulates to a certain amount, the pneumatic device automatically draws the powder into the electrostatically polarized water-blocking powder storage container.

[0068] According to an embodiment of the present invention, a method for manufacturing a fully dry loose tube utilizes the aforementioned manufacturing equipment and includes: laying out optical unit 2; electrostatically polarizing the laid-out optical unit 2; adding electrostatically polarized water-blocking powder 17 with opposite polarity to the electrostatically polarized optical unit 2, thereby coupling the optical unit 2 and the water-blocking powder 17 to form an optical fiber bundle; extruding the optical fiber bundle to form a loose tube; and shaping, cooling, and winding the loose tube.

[0069] In one embodiment, the step of extruding the fiber bundle and forming the extruded fiber bundle into a loose tube includes:

[0070] During the extrusion process, gas is introduced into the plastic layer, making the inside of the plastic layer hollow and forming a loose tube;

[0071] The loose sleeve is inserted into the vacuum water tank 8, and the roundness of the loose sleeve is adjusted using the vacuum water tank 8.

[0072] In one embodiment, the step of adding electrostatically polarized water-blocking powder 17 with opposite polarity to the electrostatically polarized optical unit 2, and coupling the optical unit 2 and the water-blocking powder 17 to form an optical fiber bundle includes:

[0073] Multiple optical units 2 are controlled to twist and twist together, and water-blocking powder 17 is added during the twisting and twisting process. The water-blocking powder 17 is sprayed from top to bottom through the spray gun of the water-blocking powder electrostatic polarization device 4 and the water-blocking powder inlet mold 53.

[0074] In the optical unit delivery step, at least one optical unit is installed on the delivery device, and active delivery is used. Among them, optical unit 2 is bare fiber, or an optical fiber combination with resin or plastic coating, and the number of optical fibers is not less than 1 core; the fiber delivery tension is adjusted to 0.5N to 3N according to the number of optical fibers and the optical fiber coating; typical optical fiber combinations include flat or round or coilable optical fiber ribbons and plastic tight-buffered optical fibers.

[0075] The optical unit is fed into the electrostatic polarization device. The current and frequency are set by the electronic controller to make the optical unit electrostatically polarized and the surface carry a positive charge.

[0076] The water-blocking powder 17 is dried in a storage container and then transported to the water-blocking powder electrostatic polarization device 4 under a certain air pressure. The electrostatic frequency, electric field density and power are set by an electronic controller to make the water-blocking powder carry a negative charge. The electrostatically polarized water-blocking powder is then sprayed out at a certain pressure through a water-blocking powder spray gun. The water-blocking powder transportation and water-blocking powder spraying are both controlled by adjustable air pressure and are linked together. That is, the larger the spraying volume, the larger the water-blocking powder transportation volume.

[0077] After electrostatic polarization, the positively charged optical unit 2 and the negatively charged water-blocking powder 17 are combined in the coupling device 5. According to the principle of electrostatic adsorption, the water-blocking powder will be uniformly and stably adsorbed on the surface of the optical unit.

[0078] By adjusting the charge of the optical unit and controlling the powder ejection flow rate, the amount of water-blocking powder adsorbed can be controlled, thereby enabling control of the water-blocking powder filling amount under different sleeve sizes and different fiber core numbers, ensuring stable water-blocking performance.

[0079] In the extrusion step of the optical fiber bundle, the optical unit 2 is coupled with the water-blocking powder 17 to form a water-blocking optical fiber bundle. After passing through the gas filling device 6 and the extruder 7, a plastic layer is coated on the outside of the optical fiber bundle to form a loose tube. The gas filling device can shape the plastic layer into a loose tube with a hollow interior and a high degree of roundness on the outside.

[0080] In the steps of shaping, cooling and winding the loose tube, the loose tube after coming out of the extruder passes through the vacuum water tank 8, cooling water tank 9, drying device 10, diameter measuring instrument 11 and traction device 12 in sequence. After the size and appearance of the loose tube are determined, it is wound up by winding device 13 to realize the preparation of the fully dry loose tube.

[0081] According to an embodiment of the present invention, the loose tube is manufactured using the above-described manufacturing method. The loose tube includes a plastic layer, a water-blocking powder 17, and an optical unit 2. The water-blocking powder 17 is wrapped around the optical unit 2 to form an optical fiber bundle. The plastic layer is covered over the optical fiber bundle. The plastic layer includes an inner surface 15 and an outer surface 14. The inner surface 15 includes a rounded surface and a concave surface 18.

[0082] In one embodiment, the performance indicators of the water-blocking powder used are as follows: particle size ≤100μm, water absorption ≥300ml / g, moisture content ≤3%, expansion rate ≥15mm / min, and expansion height ≥18mm in 3min.

[0083] To reduce the frictional resistance of the multiple optical units 2 during the filling process, a certain proportion of lubricant powder can be mixed into the water-blocking powder 17. Common lubricant powders include polyethylene wax, calcium stearate, talc, molybdenum disulfide, and silica powder, etc., and their addition amount is 0.2% to 0.8% of the water-blocking powder by weight.

[0084] In one embodiment, the concave surface 18 occupies 10% to 25% of the arc of the inner surface 15 of the plastic layer.

[0085] In one embodiment, the radius of curvature of the concave surface 18 is less than or equal to half the thickness of the plastic layer at its location; and / or, the curvature of the concave surface 18 ranges from 0 to π.

[0086] By limiting the curvature and radius of curvature of the concave surface 18, it is possible to prevent the minimum thickness at the concave surface from being too small due to the excessively large radius of curvature, which would affect the compressive strength of the loose sleeve.

[0087] In one embodiment, the concave surface 18 is a rough surface.

[0088] Through the special design of the extrusion die, the concave surface is not smooth, and the rough surface has linear patterns; common patterns include waves, lines, etc.

[0089] The above-mentioned design on the inner surface of the plastic layer has the following functions: a) It reduces the shedding of water-blocking powder 17 from the loose tube. During long-term storage and installation, the coupling force between the water-blocking powder 17 and the optical unit 2 will gradually decrease due to external vibrations, meaning that the water-blocking powder 17 may detach and overflow from the loose tube, thus affecting the water-blocking performance. The concave design of the inner layer surface allows the water-blocking powder 17 to adhere to the concave surface 18, reducing the overflow of water-blocking powder 17 from the loose tube, which is particularly suitable for scenarios where optical cables need to be installed vertically. b) The concave surface 18 can also store and collect water-blocking powder 17 that has detached from the optical unit 2, so that the detached water-blocking powder 17 does not affect the transmission performance of the optical fiber, and the water-blocking powder 17 can still be preserved in the loose tube without affecting the water-blocking performance.

[0090] In one embodiment, the plastic layer is filled with at least one anti-shrinkage film 16 that extends continuously along the axial direction of the loose tube. The anti-shrinkage film 16 is arc-shaped in the cross-section of the loose tube, and its purpose is to prevent the loose tube from shrinking axially, especially for large-sized loose tubes, and to solve the problem of post-shrinkage that occurs during the molding process.

[0091] In one embodiment, the anti-shrinkage film 16 has a longitudinal shrinkage rate of ≤0.2% at 250℃~300℃, a thickness of 0.5mm~0.2mm, and a width of 0.5mm~5mm.

[0092] The anti-shrinkage film has excellent thermal stability, with a longitudinal shrinkage rate of ≤0.2% at 250℃~300℃; the thickness is 0.05mm~0.2mm and the width is 0.5mm~5mm; the anti-shrinkage film is curved at a certain arc in the plastic layer; the common tensile films are one of polyimide film, liquid crystal polymer film, polybenzimidazole film, and polytetrafluoroethylene film.

[0093] In one embodiment, the anti-shrinkage membrane 16 is spirally arranged in the plastic layer at a certain pitch; the shrinkage rate after loosening the sleeve is ≤0.2%.

[0094] In one embodiment, the outer diameter of the loose sleeve ranges from 0.8 mm to 20 mm, and the wall thickness ranges from 0.08 mm to 1 mm. When the outer diameter of the loose sleeve is less than or equal to 5.0 mm, the plastic layer material is one of PBT, PP, TPEE, and PC; when the outer diameter of the loose sleeve is greater than 5.0 mm, the plastic layer material is one of TPEE, PE, and PP.

[0095] According to an embodiment of the present invention, the optical cable includes a cable core made of the loose tube described above and an outer sheath covering the cable core.

[0096] The main advantages of this invention are:

[0097] 1. By adopting electrostatic polarization technology and setting the electrostatic frequency, electric field density and power through an electronic controller, the optical unit and water-blocking powder are respectively equipped with positive and negative charges, and the amount of charge is controllable.

[0098] 2. A coupling device for the optical unit and the water-blocking powder was designed to realize the active coupling of the water-blocking powder on the surface of the optical unit. The amount of water-blocking powder adsorbed can be controlled by adjusting the powder spray flow rate. At the same time, the excess water-blocking powder can be automatically recycled and reused.

[0099] 3. The fully dry loose tube production system enables the fabrication of tubes with outer diameters ranging from 0.8mm to 20mm, wall thicknesses from 0.08mm to 1mm, and out-of-roundness ≤5%. A single tube can accommodate up to 864 optical fiber cores, meeting the application requirements for different core counts in optical cables. The loose tube's plastic layer is filled with an anti-shrinkage film, effectively improving its longitudinal shrinkage. A special inner surface design reduces the risk of water-blocking powder overflowing from the tube, enhancing its water-blocking stability during long-term use.

[0100] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0101] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0102] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An apparatus for manufacturing a full dry loose tube, characterized by comprising: The application relates to a manufacturing device for manufacturing an optical fiber bundle, comprising: a wire feeding device (1); a light unit electrostatic polarization device (3) arranged downstream of the wire feeding device (1) and used for electrostatically polarizing light units (2) entering the light unit electrostatic polarization device (3); a coupling device (5) arranged downstream of the light unit electrostatic polarization device (3) and used for receiving the light units (2) electrostatically polarized by the light unit electrostatic polarization device (3); a water-blocking powder electrostatic polarization device (4) connected to the coupling device (5) and used for sending the electrostatically polarized water-blocking powder (17) into the coupling device (5) to be coupled with the light units (2) to form the optical fiber bundle, wherein the polarity of the light units (2) is opposite to that of the water-blocking powder (17); an extruder (7) used for receiving the optical fiber bundle and coating a plastic layer on the optical fiber bundle, wherein the plastic layer is coated on the optical fiber bundle, the plastic layer comprises an inner surface (15), the inner surface (15) comprises a rounded surface and a concave surface (18), and the concave surface (18) is a rough surface; a vacuum water tank (8) arranged downstream of the extruder (7) and used for rounding the optical fiber bundle coated with the plastic layer to form a loose tube; and a cooling water tank (9) used for cooling the rounded loose tube.

2. The manufacturing apparatus according to claim 1, characterized by The manufacturing device further comprises a gas filling device (6) arranged upstream of the extruder (7) and used for injecting a gas with a preset pressure into the plastic layer when the extruder (7) coats the plastic layer on the optical fiber bundle.

3. The manufacturing apparatus according to claim 1, wherein The coupling device (5) comprises a coupling box, the coupling box comprises a light unit inlet die (51), a light unit outlet die (52) and a water-blocking powder inlet die (53), the light unit inlet die (51) has a plurality of inlet die holes, a plurality of the light units (2) enter the coupling device (5) through the inlet die holes, the light unit outlet die (52) is arranged on the opposite side of the light unit inlet die (51) and has one outlet die hole, and the water-blocking powder inlet die (53) is arranged on the upper side of the coupling device (5) and connected with a spray gun of the water-blocking powder electrostatic polarization device (4).

4. The manufacturing apparatus according to claim 3, wherein The centers of the plurality of inlet die holes of the light unit inlet die (51) are located on the same circle coaxial with the outlet die hole, and the light unit inlet die (51) is rotatable relative to the central axis of the outlet die hole.

5. The manufacturing apparatus according to claim 3, wherein The light unit inlet die (51) is of a detachable structure.

6. The manufacturing apparatus according to claim 3, wherein The coupling device (5) further comprises a vibrating screen (54) and a water-blocking powder recovery device (55), the bottom of the coupling box is open, the vibrating screen (54) is arranged on the bottom of the coupling box, and the water-blocking powder recovery device (55) is arranged below the vibrating screen (54).

7. The manufacturing apparatus according to claim 6, wherein The water-blocking powder recovery device (55) comprises a heating device, a pipeline and a pneumatic device, the pipeline is connected with a storage container used for storing the electrostatically polarized water-blocking powder (17), the heating device is used for heating the water-blocking powder (17) recovered in the water-blocking powder recovery device (55), and the pneumatic device is used for sucking the water-blocking powder (17) into the storage container.

8. A manufacturing method of a full dry type loose tube, which applies the manufacturing apparatus according to any one of claims 1 to 7, characterized by, The application further relates to a manufacturing method for manufacturing an optical fiber bundle, comprising the following steps: feeding light units (2); Electrostatically polarizing the light unit (2) after being released; Adding water-blocking powder (17) with opposite polarity to the electrostatically polarized light unit (2) to couple the light unit (2) and the water-blocking powder (17) to form a fiber bundle; Extruding the fiber bundle and forming a loose tube after extrusion; Shaping, cooling and winding the loose tube.

9. The production method according to claim 8, wherein The step of extruding the fiber bundle and forming a loose tube after extrusion includes: During the extrusion process, gas is introduced into the plastic layer to make the inside of the plastic layer hollow, forming a loose tube; The loose tube is sent into the vacuum water tank (8), and the roundness of the loose tube is adjusted by the vacuum water tank (8).

10. The manufacturing method according to claim 8, wherein The step of adding water-blocking powder (17) with opposite polarity to the electrostatically polarized light unit (2) to couple the light unit (2) and the water-blocking powder (17) to form a fiber bundle includes: Controlling the twisted and twisted light unit (2) and adding water-blocking powder (17) during the process, the water-blocking powder (17) is sprayed from the water-blocking powder inlet mode (53) above to below by the water-blocking powder electrostatic polarization device (4) spray gun.

11. A loose tube, which is manufactured by the manufacturing method according to claim 8, characterized in that, The loose tube includes a plastic layer, water-blocking powder (17) and a light unit (2), the water-blocking powder (17) is wrapped outside the light unit (2) to form a fiber bundle, the plastic layer is coated outside the fiber bundle, the plastic layer includes an inner surface (15), the inner surface (15) includes a round surface and a concave surface (18).

12. The loose tube according to claim 11, characterized in that, The concave surface (18) occupies an arc proportion of 10% to 25% of the inner surface (15) of the plastic layer.

13. The loose tube as claimed in claim 11, characterized in that, The curvature radius of the concave surface (18) is less than or equal to half of the thickness of the plastic layer at the location; and / or, the concave surface (18) has an arc range of 0 to π.

14. The loose tube according to claim 11, characterized in that, The concave surface (18) is a rough surface.

15. The loose tube as claimed in claim 11, wherein, The plastic layer is filled with at least one anti-shrinkage film (16) continuously extending along the axial direction of the loose tube, and the anti-shrinkage film (16) is arc-shaped in the cross section of the loose tube.

16. The loose tube as claimed in claim 15, characterized in that, The longitudinal shrinkage rate of the anti-shrinkage film (16) is ≤0.2% at 250-300°C, the thickness is 0.5-0.2mm, and the width is 0.5-5mm.

17. The loose tube according to claim 11, wherein, The outer diameter of the loose tube is 0.8-20mm, and the wall thickness is 0.08-1mm, when the outer diameter of the loose tube is less than or equal to 5.0mm, the plastic layer material is one of PBT, PP, TPEE and PC; when the outer diameter of the loose tube is greater than 5.0mm, the plastic layer material is one of TPEE, PE and PP.

18. An optical cable, characterized by A cable core prepared from the loose tube of any one of claims 11 to 17 and an outer sheath coated outside the cable core.

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