KR100288740B1 - Cooler for manufacturing of metal coated optical fiber - Google Patents

Abstract

PURPOSE: A cooling apparatus is provided to improve a mechanical strength of an optical fiber by increasing a cooling efficiency when cooling a metal-coated optical fiber, and to suppress oxidation phenomenon caused when an optical fiber of a quartz glass is cooled. CONSTITUTION: A cooling apparatus(114) has a dual structure of an outer tube(36) and an inner tube(34). A cooling gas(52) for cooling a metal-coated optical fiber flows through the inner tube. An upper and lower support tables(26, 42) are installed at upper and lower parts of the inner tube(34) and the outer tube(36). An adjustment part(44) is installed at the center of the lower support table so as to adjust the size of a lower hole(46). A guide bracket(20) is installed at the center of the upper support table(26) and guides a coated optical fiber so as to be inserted in the inner tube(34). A lower part of the upper hole(24) is inclined by a predetermined angle so that the cooling gas(52) flows toward a side outlet(28). A cooling water supplying port(38) is installed at one side of the outer tube(36) so as to supply cooling water(50) toward the outer tube(36). A gas supply port(40) is installed at one side of the inner tube(34) so as to supply the cooling gas toward the inner tube.

Description

COOLER FOR MANUFACTURING OF METAL COATED OPTICAL FIBER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber drawing device, and more particularly, to a cooling device for manufacturing a metal coated optical fiber which can increase the cooling efficiency when cooling a metal coated optical fiber.

Usually, the optical fiber of the silica component for optical communication is a thin glass fiber whose outer diameter is about 100 micrometers-150 micrometers, and it is very weak unless it is coated, and it breaks easily. Glass is a material that exhibits different fractures from metals, so micro-defects on the surface of the fiber grow and local stress concentrations in the area are the cause of failure. In addition, the silica-based optical fiber has a characteristic of high strength or very vulnerable to moisture in theory of about 20 GPa or more, and when the water contacts the surface of the optical fiber, the strength of the optical fiber decreases drastically.

Therefore, a metal-coated optical fiber is used to protect the surface of the optical fiber, to improve tensile strength, bending strength, and to prevent moisture penetration, thereby making it easy to handle. There are many ways to do this. The most widely used method is a freezing method in which an optical fiber passes through molten metal and is coated. The conventional freezing method as described above is described in detail in the application No. 96-12918 filed by the present inventor (name: extraction apparatus and manufacturing method of a metal-coated optical fiber). It is also described in great detail in US Pat. No. 4,894,078 (name: optical fiber manufacturing method and apparatus) and US Pat. No. 4,437,870 (name: cooling apparatus of optical fiber).

However, the optical fiber subjected to the metal coating by the above method is coated with the surface of the optical fiber with a metal material such as copper and aluminum having a high melting temperature, so that the surface of the quartz glass is crystallized when the optical fiber is coated with the hot metal immediately after cooling. The surface of the quartz glass optical fiber becomes brittle. As a result, not only the strength of the optical fiber is weak, but also the high temperature metal is exposed to the atmosphere, which reacts with the surrounding oxygen, causing oxidation reaction on the metal surface, resulting in a significant decrease in optical properties.

Accordingly, an object of the present invention is to provide a cooling device for manufacturing a metal coated optical fiber which can improve the mechanical strength of the optical fiber by increasing the cooling efficiency when cooling the metal coated optical fiber.

Another object of the present invention is to provide a cooling device for producing a metal coated optical fiber which can suppress oxidation phenomenon occurring while the metal coated quartz glass optical fiber is cooled.

Still another object of the present invention is to provide a cooling device for manufacturing a metal-coated optical fiber which can prevent metal solidification from occurring in the metal coating device according to an increase in the flow rate of the refrigerant gas.

Still another object of the present invention is to provide a cooling device for manufacturing a metal coated optical fiber which can continuously pull out a metal coated optical fiber.

In order to achieve the above object, the optical fiber withdrawal comprising a melting furnace for melting the preform according to the present invention to a high temperature to the uncovered optical fiber, and a metal coating device for coating the surface of the uncoated optical fiber with a metal material The device,

A cooling tube having a dual structure consisting of an outer tube and an inner tube inserted into the outer tube;

An upper supporter and a lower supporter installed at both ends of the cooling tube;

A guide bracket installed at the center of the upper supporter and having an upper hole for guiding the coated optical fiber into the inner tube;

A plurality of side outlets formed along an outer circumference of the guide bracket and configured to discharge the cooling gas flowing into the inner tube to the outside;

A gas supply port connected to a lower side of the inner tube to supply the cooling gas;

A cooling water supply port connected to a lower side of the outer tube to supply cooling water to a space between the outer tube and the inner tube;

It is connected to the upper side of the outer tube characterized in that it comprises a cooling water discharge port for discharging the cooling water.

1 is a schematic view showing the configuration of a manufacturing apparatus for withdrawing a metal-coated optical fiber according to an embodiment of the present invention.

Figure 2 is a side cross-sectional view showing the configuration of a cooling device for cooling the metal-coated optical fiber according to an embodiment of the present invention.

3 is a plan view of the cooling apparatus in FIG.

<Explanation of symbols for main parts of drawing>

20: guide bracket 24: upper hole

28: side outlet port 30: cooling water discharge port

32: slope 34: cooling tube (inside)

36: cooling tube (outer) 38: cooling water supply port

40: gas supply port 50: cooling water

52: gas for cooling 114: cooling device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed descriptions of related well-known functions or configurations will be omitted if they may obscure the gist of the present invention.

Figure 1 is a schematic diagram showing the configuration of a manufacturing apparatus for withdrawing a metal-coated optical fiber according to an embodiment of the present invention.

In the method of drawing a metal-coated optical fiber according to an embodiment of the present invention, the preform 100 is slowly supplied to the melting furnace 102. Thereafter, the preform 100 is heated to a high temperature of 2000 ° C. or higher in the melting furnace 102, and drawn out to an uncovered optical fiber 10a having a diameter of 125 μm. The injecting force is then applied to the uncovered optical fiber 10a and provided from capstan 116. Subsequently, the outer diameter measuring instrument 104 determines whether the diameter of the uncovered optical fiber 10a to be a predetermined diameter (generally 125 탆) is transmitted to a diameter controller (not shown). The diameter controller then controls the capstan 116 such that the diameter of the uncovered optical fiber 10a is maintained at 125 [mu] m. Thereafter, the uncovered optical fiber 10a passing through the outer diameter measuring instrument 104 is introduced into the metal coating device 106. The uncovered optical fiber 10a is then coated with copper, tin or aluminum. After the metal-coated optical fiber 10b is cooled in the cooling apparatus 114 of the present invention, the optical fiber 10b is wound on the spool 118 by the in-output of the capstan 116. As a result, the drawing process of the metal-coated optical fiber is completed.

In the process of drawing out the metal-coated optical fiber by the above method, the cooling device 114 of the present invention for cooling the metal-coated optical fiber 10b by the coating device 106 is as shown in FIGS. 2 and 3.

That is, the cooling device 114 is composed of a dual structure of the outer tube 36 and the inner tube 34. The inner tube 34 flows a cooling gas 52 for cooling the metal-coated optical fiber 10b. The outer tube 36 flows with coolant 50 which reduces the surface temperature of the inner tube 34. The upper support 26 and the lower support 42 are installed on the upper and lower ends of the inner tube 34 and the outer tube 36. The center of the lower support 42 is provided with an adjusting unit 44 for adjusting the size of the lower hole 46. At this time, the cooled optical fiber 10b is led downward through the lower hole 46. At the center of the upper support 26 is a guide bracket 20 for guiding the coated optical fiber 10a to be inserted into the inner tube 34. Here, the guide bracket 20 is formed of a graphite material to withstand high temperatures, and also protrudes upward by about ″ a ″ lengths relative to the upper surface of the upper support 26, and downwards with the lower surface of the upper support 26 downward. It is installed to protrude about ″ b ″ length.

At this time, the reason why the installation so as to protrude by the length ″ a ″ is to prevent exposure to the external environment as close as possible to the coated portion of the metal coating apparatus. This is to prevent the flow (vibration) of the optical fiber 10a when the coated optical fiber 10a is cooled. In addition, an upper hole 24 having a predetermined size is formed in the central axis of the guide bracket 20, and the coated optical fiber 10a flows into the inner tube 34 through the upper hole 24. In addition, the upper end of the upper hole 24 is formed in the shape of a V-groove to prevent the interference occurs when the optical fiber 10a is introduced into the upper hole 24. At the lower end of the upper hole 24, the inclined surface 32 is inclined to a predetermined angle so that the cooling gas 52 flows toward the side outlet 38. In this case, as shown in FIG. 3, a plurality of side outlets 38 are formed along the circumference of the guide bracket 20, and serves to discharge the cooling gas 52 to the outside. For example, four side outlets 38 may be formed in a cross shape. In addition, a cooling water supply port 38 for supplying cooling water 50 to the outer tube 36 is installed at one lower side of the outer tube 36. The upper one side of the outer tube 36 is provided with a cooling water discharge port 30 for discharging the cooling water 50 introduced into the outer tube 36 to the outside. In addition, the lower side of the inner tube 34 is provided with a gas supply port 40 for supplying the cooling gas 52 toward the inner tube 36. At this time, the cooling gas 52 is mainly used helium (He) gas, the cooling gas 52 after cooling the coated optical fiber 10a is discharged to the outside through the side outlet 28 and the upper hole 24.

An operation process of the cooling apparatus of the present invention configured as described above will be described with reference to FIGS. 1 and 2.

First, as described in FIG. 1, the uncovered optical fiber 10a drawn out from the preform 100 is subjected to a metal coating while passing through the coating device 106. After that, the metal-coated optical fiber 10b is introduced into the cooling device 114. That is, the optical fiber 10b is introduced into the inner tube 34 through the upper hole 24 of the guide bracket. Subsequently, the cooling gas 52 such as helium is supplied to the inner tube 34 through the gas supply port 40, and the cooling water 50 is supplied to the outer tube 36 through the cooling water supply port 50. Thereafter, the optical fiber 10b is gradually cooled by the cooling gas 52, and the cooling gas 52 is cooled toward the side outlet 28 along the inclined surface 32 of the guide bracket and discharged to the outside through the side outlet 28. At the same time, the cooling water 50 is discharged to the outside through the cooling water discharge port 30. The cooled optical fiber 10b is then continuously drawn down by the output of the capstan 116. At this time, most of the cooling gas 52 is discharged through the side outlet 28, and some of the cooling gas 52 exits through the upper hole 24 to cool the optical fiber 10b flowing into the inner tube 34. In addition, since the optical fiber 10b just outside the sheathing device 106 has a temperature of several hundred degrees, the upper part of the cooling device 114 receives very high heat, so that the coolant 50 is supplied to the outer tube 36 through the coolant supply port 38 and the coolant discharge port 30. As it exits, the cooling system 114 itself reduces the heat to maximize cooling efficiency.

As described above, the metal coating optical fiber manufacturing apparatus according to the embodiment of the present invention is a metal as most of the cooling gas is passed through the side outlet of the cooling apparatus even if a large amount of gas for cooling to increase the cooling efficiency. Since the molten coating device is not directly affected, the surface of the optical fiber can be uniformly coated. In addition, some of the cooling gas is discharged through the upper hole of the guide bracket to quickly cool the high-temperature metal-coated optical fiber, and prevent overheating of the cooling device and deterioration of cooling efficiency due to radiant heat of the high-temperature metal-coated optical fiber. Can be. In addition, the surface of the metal and the glass optical fiber do not undergo a crystallization reaction, and thus the strength of the optical fiber can be prevented from being lowered, and the oxidation of the metal coating layer due to the high temperature can be prevented. In addition, by performing a uniform coating process there is an effect that can continuously produce a metal-coated optical fiber.

Claims (5)

An optical fiber drawing device comprising: a melting furnace for melting a preform to a high temperature in order to extract the preform into an uncovered optical fiber, and a metal coating device for coating a surface of the uncovered optical fiber with a metal material; A cooling tube having a dual structure consisting of an outer tube and an inner tube inserted into the outer tube; An upper supporter and a lower supporter installed at both ends of the cooling tube; A guide bracket installed at the center of the upper supporter and having an upper hole for guiding the coated optical fiber into the inner tube; A plurality of side outlets formed along an outer circumference of the guide bracket and configured to discharge the cooling gas flowing into the inner tube to the outside; A gas supply port connected to a lower side of the inner tube to supply the cooling gas; A cooling water supply port connected to a lower side of the outer tube to supply cooling water to a space between the outer tube and the inner tube; Cooling apparatus for producing a metal-coated optical fiber characterized in that it comprises a cooling water discharge port connected to the upper side of the outer tube for discharging the cooling water. The apparatus of claim 1, wherein the cooling gas is helium. The guide bracket of claim 1, wherein the guide bracket protrudes upward by a predetermined length ″ a ″ based on the upper support to prevent the coated optical fiber from being quenched, and the guide bracket cools the coated optical fiber. Cooling device for producing a metal-coated optical fiber, characterized in that protruding downward by a predetermined length ″ b ″ based on the upper support to prevent flow when. The cooling device for manufacturing a metal-coated optical fiber of claim 1, wherein the lower end surface of the guide bracket is formed to be inclined at a predetermined angle so that the cooling gas flows toward the side outlet. The apparatus of claim 1, wherein the guide bracket is made of graphite.

Images