JPH0632630A - Production of optical fiber - Google Patents

Abstract

PURPOSE:To produce optical fiber by cooling optical fiber while suppressing leakage of a cooling liquid. CONSTITUTION:Optical fiber 3 obtained by spinning optical fiber preform from a heating and melting part is passed through a cooling container 5 charged with a cooling liquid 4 and the cooled optical fiber 3 is passed through a resin applying device to coat the surface of the optical fiber with the resin. In the operation, the optical fiber 3 is chilled while evacuating a pressure reduction room 5a at the upper part of cooling container 5 charged with the cooling liquid 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber obtained by spinning from a heating and melting portion of an optical fiber base material, cooled by passing the optical fiber through a cooling container containing a cooling liquid, and then coating the optical fiber with a resin. The present invention relates to a method for manufacturing an optical fiber in which the surface of the optical fiber is coated with a resin through a container.

[0002]

2. Description of the Related Art An optical fiber obtained by heating and melting an optical fiber preform in a heating and melting furnace and spinning from the heating and melting portion of the optical fiber preform has a high temperature. When attempting to coat the resin through a container, the temperature of the optical fiber lowers the viscosity of the resin, and the resin cannot be coated to a predetermined thickness.

Therefore, a cooling cylinder is arranged between the heating and melting furnace and the resin coater, and a cooling gas such as helium is caused to flow in the cooling cylinder to continuously cool the optical fiber passing therethrough. Is commonly done.

However, in such a cooling method,
There was a problem that the cooling efficiency was poor and it could not cope with the increase in the drawing speed of the optical fiber.

In order to deal with such a problem, a method of manufacturing an optical fiber preform as shown in FIGS. 4 and 5 has been proposed.

In this method for producing an optical fiber preform, the optical fiber preform 1 is heated and melted in the heating / melting furnace 2 and spun from the heating / melting portion 1a of the optical fiber preform 1. The optical fiber 3 is cooled by passing it through a cooling container 5 containing a cooling liquid 4, and the cooled optical fiber 3 is passed through a resin coater 6 to coat the surface of the optical fiber 3 with a resin. This is done by curing the coating resin of the fiber core wire 3a with a resin curing device (not shown), and then winding it up onto the winding bobbin (not shown) through the capstan 7. In this case, the cooling liquid 4 is supplied from the cooling liquid supply container 8 through the supply pipe 9 into the cooling container 5.

When the cooling liquid 4 is used in this way, the optical fiber 3 is cooled as it passes through the cooling liquid 4, and the cooling liquid 4 attached to the surface of the optical fiber 3 is passed through the optical fiber passage hole of the cooling container 5. When it goes out of 10 and vaporizes, it is cooled by removing the heat of vaporization. Therefore, the optical fiber 3 can be efficiently cooled.

[0008]

However, in such a cooling method using the cooling liquid 4, it is difficult to seal the cooling liquid 4 from the optical fiber passage hole 10 of the cooling container 5, and the cooling liquid 4 leaks out. As a result, the amount of the cooling liquid 4 consumed becomes large and the cooling cost becomes high.

An object of the present invention is to provide a method of manufacturing an optical fiber which can cool the optical fiber while suppressing the leakage of the cooling liquid.

[0010]

Means for Solving the Problem To explain the means of the present invention for achieving the above object, the present invention is to cool an optical fiber obtained by spinning from a heating / melting portion of an optical fiber preform with a cooling liquid. A method of manufacturing an optical fiber, wherein the cooling liquid is passed through a container, and the cooled optical fiber is passed through a resin coater to coat the surface of the optical fiber with a resin. The optical fiber is cooled while being cooled.

[0011]

By thus reducing the pressure in the cooling container containing the cooling liquid, the leakage of the cooling liquid from the optical fiber passage hole of the cooling container can be suppressed. Therefore, according to the present invention, it is possible to cool the optical fiber while suppressing the leakage of the cooling liquid from the optical fiber passage hole of the cooling container.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an optical fiber cooling device 11 in a first embodiment of an optical fiber manufacturing apparatus used when carrying out an optical fiber manufacturing method according to the present invention. In this optical fiber cooling device 11, a cooling liquid supply container 8 is connected to the lower side of the cooling container 5 via a supply pipe 9. A vacuum pump 13 is connected to the decompression chamber 5 a in the upper part of the cooling container 5 via a connecting pipe 12.

Therefore, in the method of manufacturing the optical fiber of this embodiment, when the optical fiber 3 is manufactured in the same manner as described above, the decompression chamber 5a in the upper portion of the cooling container 5 containing the cooling liquid 4 is connected to the connecting pipe. The optical fiber 3 is cooled with the cooling liquid 4 while the vacuum pump 13 draws a vacuum via 12 to reduce the pressure.

By depressurizing the inside of the cooling container 5 containing the cooling liquid 4 in this way, the cooling container 5 is kept at a negative pressure, and the leakage of the cooling liquid 4 from the optical fiber passage hole 10 can be suppressed. Therefore, according to this manufacturing method, the optical fiber 3 can be cooled while suppressing the leakage of the cooling liquid 4 from the optical fiber passage hole 10 of the cooling container 5.

When the pressure inside the cooling container 5 is reduced, the cooling liquid 4 is supplied from the cooling liquid supply container 8 through the supply pipe 9 to the inside of the cooling container 5 due to the pressure difference between the cooling liquid supply container 8 and the cooling liquid supply container 8. . As the cooling liquid 4, it is preferable to use a volatile liquid such as alcohol. If a volatile liquid is used as the cooling liquid 4, the cooling liquid 4 is easily evaporated because the pressure inside the cooling container 5 is reduced, and thus the heat of evaporation can cool the optical fiber 3 more efficiently. be able to.

FIG. 2 shows an example of the optical fiber cooling device 11 in the second embodiment of the optical fiber manufacturing apparatus used when carrying out the optical fiber manufacturing method according to the present invention. In this optical fiber cooling device 11, decompression chambers 5a and 5b are provided in upper and lower stages (two stages in this example) in the upper part of the cooling container 5, and these decompression chambers 5a and 5b are formed by the optical fiber passage hole 14. This is an example of communication.

In this way, the pressure inside the cooling container 5 can be reduced more efficiently than in the first embodiment.

FIG. 3 shows an example of the optical fiber cooling device 11 and the decompression container 15 in the third embodiment of the optical fiber manufacturing apparatus used for carrying out the optical fiber manufacturing method according to the present invention. .

In this embodiment, a decompression container 15 is arranged below the cooling container 5. Decompression chamber 15 inside decompression container 15
The pressure of a is reduced from the pressure reducing port 15b by a vacuum pump. The vacuum pump for decompressing the decompression chamber 15a may be a dedicated one, or the optical fiber cooling device 11
It may also be used as the vacuum pump 13.

By doing so, the cooling liquid 4 adhering to the surface of the optical fiber 3 which has passed through the cooling container 5 is removed from the decompression chamber 1.
It is more preferable because it is vaporized by 5a and takes heat of the optical fiber 3 at this time.

[0021]

As described above, in the method of manufacturing an optical fiber according to the present invention, the optical fiber obtained by spinning from the heating and melting part of the optical fiber preform is passed through the cooling container containing the cooling liquid. When the resin is coated on the surface of the optical fiber by passing the cooled optical fiber through a resin coating device, the optical fiber is cooled while the pressure inside the cooling container containing the cooling liquid is reduced. Leakage of the cooling liquid from the optical fiber passage hole of the cooling container can be suppressed. Therefore, according to the present invention, it is possible to cool the optical fiber while suppressing the leakage of the cooling liquid from the optical fiber passage hole of the cooling container. Therefore, the consumption of the cooling liquid can be made smaller than in the conventional case, and the optical fiber can be manufactured while reducing the cooling cost.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an optical fiber cooling device in a first embodiment of an optical fiber manufacturing apparatus used when carrying out an optical fiber manufacturing method according to the present invention.

FIG. 2 is an optical fiber cooling device in a second embodiment of an optical fiber manufacturing apparatus used when carrying out an optical fiber manufacturing method according to the present invention.

FIG. 3 is a vertical cross-sectional view of an optical fiber cooling device and a decompression container in a third embodiment of an optical fiber manufacturing apparatus used when carrying out an optical fiber manufacturing method according to the present invention.

FIG. 4 is a vertical cross-sectional view showing a schematic configuration of a conventional optical fiber manufacturing apparatus.

5 is a vertical cross-sectional view of the optical fiber cooling device used in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber base material 1a Heating / melting part 2 Heating / melting furnace 3 Optical fiber 4 Cooling liquid 5 Cooling containers 5a, 5b Decompression chamber 6 Resin coating device 7 Capstan 8 Cooling liquid supply container 9 Supply pipe 10 Optical fiber passage hole 11 Optical fiber Cooling device 12 Connection pipe 13 Vacuum pump 14 Optical fiber passage hole 15 Decompression container 15a Decompression chamber 15b Decompression port

Claims (1)

[Claims] 1. An optical fiber obtained by spinning from a heating and melting portion of an optical fiber base material is passed through a cooling container containing a cooling liquid to be cooled, and the cooled optical fiber is passed through a resin coater. A method of manufacturing an optical fiber, wherein the surface of the optical fiber is coated with a resin, wherein the optical fiber is cooled while depressurizing the inside of the cooling container containing the cooling liquid.