JPH059042A - Production of coated optical fiber - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method of manufacturing an optical fiber or an optical fiber core, which enables economical and efficient cooling and resin coating. [Structure] An optical fiber 3 is spun from the melted portion while the lower part of the optical fiber preform 1 is heated in a drawing furnace 2, and the optical fiber 3 is passed through a primary resin coating die 4 to coat the primary resin. The obtained primary coated optical fiber core wire 3a is passed through a primary resin curing device 5 to cure the primary coated resin, and then this optical fiber core wire 3a
Is contacted with the liquid nitrogen 7 in the liquid nitrogen reservoir 6 to be cooled. The cooled primary coated optical fiber core wire 3a is passed through the secondary resin coating die 12 to coat the secondary resin. Obtained secondary coated optical fiber core wire 3b
Is passed through the secondary resin curing device 13 to cure the secondary coating resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention manufactures an optical fiber core wire by drawing an optical fiber from a heated optical fiber base material, passing the optical fiber through a resin coating die, and coating the outer periphery of the optical fiber with a resin. The present invention relates to a method for manufacturing an optical fiber core wire.

[0002]

2. Description of the Related Art Conventionally, an optical fiber core wire has been manufactured by drawing an optical fiber from an optical fiber preform heated to about 2000 ° C. in a drawing furnace and passing the optical fiber through a resin-coated die to form an outer periphery of the optical fiber. This is done by coating the resin with a resin and then heating it to about 500 ° C. through a resin curing device such as an ultraviolet irradiation furnace or a baking oven to cure the coating resin. For this reason, the optical fiber is hot immediately after leaving the drawing furnace or the resin curing device.

[0003]

Therefore, if the drawing speed becomes faster or the coating diameter of the resin becomes larger, the temperature of the optical fiber or the optical fiber core wire becomes higher, and when the resin is subsequently applied. However, there is a problem that the resin becomes difficult to adhere to the surface of the optical fiber or the optical fiber core wire.

In order to avoid this, it has been proposed to cool the optical fiber or the optical fiber core wire with helium gas to make it easier to coat the resin, but helium gas has a low cooling capacity for its cost. There was a point.

It is an object of the present invention to provide a method of manufacturing an optical fiber or an optical fiber core wire, which can be coated with resin while cooling the optical fiber or the optical fiber core wire economically and efficiently.

[0006]

Means for Solving the Problem To explain the means of the present invention for achieving the above object, the present invention is to draw an optical fiber from an optical fiber preform heated in a drawing furnace and to apply the optical fiber to a resin-coated die. In the method for producing an optical fiber core wire by coating the outer circumference of the optical fiber with a resin to produce an optical fiber core wire, the optical fiber or the optical fiber core wire is passed through liquid nitrogen to be cooled, and then the resin is coated. It is characterized by performing.

[0007]

When the optical fiber or the optical fiber core wire is cooled by passing through the liquid nitrogen as described above, the liquid nitrogen has a high cooling efficiency and can be cooled at a lower cost than the helium gas.

[0008]

Embodiments of the present invention will now be described in detail with reference to FIGS. In this embodiment, the optical fiber preform 1
The lower part of the fiber is heated in the drawing furnace 2 and the optical fiber 3 is spun from the melted portion, and the optical fiber 3 is passed through a primary resin coating die 4 to coat a primary resin such as an ultraviolet curable resin. The obtained primary coated optical fiber core wire 3a is passed through a primary resin curing device 5 such as an ultraviolet curing furnace to cure the primary coated resin, and then the primary coated optical fiber core wire 3a is stored in a liquid nitrogen reservoir 6 with liquid nitrogen 7 Touch to cool. The liquid nitrogen 7 is supplied to the liquid nitrogen reservoir 6 from the liquid nitrogen tank 8 through a tube 9
Through.

The cooled primary coated optical fiber core wire 3a is obtained by coating a secondary resin such as an ultraviolet curing resin through a secondary resin coating die 12 while measuring the temperature with a thermometer 11 having a temperature sensor 10. The secondary coated optical fiber core wire 3b is passed through a secondary resin curing device 13 such as an ultraviolet curing furnace to cure the secondary coated resin, and the capstan 14 changes the direction to wind the winding onto a winding bobbin (not shown).

In the experiment, the drawing speed of the optical fiber 3 was set to 18
First, the primary coated optical fiber core wire 3 is set to 0 m / min.
When a was not cooled with liquid nitrogen 7 and the temperature was measured with the temperature sensor 10 at 1.5 m after exiting the primary resin curing device 5, it was 123 ° C. The outer diameter of the secondary coated optical fiber core wire 3b was 244 μm.

Next, a liquid nitrogen reservoir 6 is provided 75 cm below the primary resin curing device 5, liquid nitrogen 7 is supplied little by little from a liquid nitrogen tank 8 by a manual pump, and the primary coated optical fiber core wire 3a is attached. Cooled. When the temperature of the primary coated optical fiber core wire 3a at this time was measured at the same position as the previous time, it was 76 ° C. The outer diameter of the secondary coated optical fiber core wire 3b was 252 μm. Therefore, it was confirmed that the secondary resin can be satisfactorily coated according to the present invention.

Although the cooling of the primary coated optical fiber core wire 3a has been described in the above embodiment, (a) cooling the bare optical fiber 3 and (b) applying a hermetic coating such as carbon coating to the bare optical fiber 3. The present invention can be similarly applied to cooling of the optical fiber core wire, (c) cooling of the bare optical fiber 3 with a metal coating, and the like.

[0013]

As described above, in the method of manufacturing an optical fiber core wire according to the present invention, the optical fiber or the optical fiber core wire is cooled by being passed through the liquid nitrogen, so that the cooling efficiency is high and lower than that of helium gas. Can be cooled at cost. Therefore, even if the drawing speed is increased or the coating diameter is increased, the coating operation can be stably performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for carrying out an optical fiber core wire manufacturing method according to the present invention.

FIG. 2 is a vertical cross-sectional view of the liquid nitrogen reservoir used in FIG.

[Explanation of Codes] 1 ... Optical fiber base material, 2 ... Drawing furnace, 3 ... Optical fiber,
3a ... Primary coated optical fiber core wire, 3b ... Secondary coated optical fiber core wire, 4 ... Primary resin coating die, 5 ... Primary resin curing device, 6 ... Liquid nitrogen reservoir, 7
... Liquid nitrogen, 8 ... Liquid nitrogen tank, 9 ... Tube, 1
0 ... Temperature sensor, 11 ... Thermometer, 12 ... Secondary resin coating die, 13 ... Secondary resin curing device.

Claims (1)

Claim: What is claimed is: 1. An optical fiber is drawn from an optical fiber preform heated in a drawing furnace, and the optical fiber is passed through a resin coating die to coat the optical fiber with resin on the outer periphery of the optical fiber. An optical fiber core wire manufacturing method for manufacturing a fiber core wire, characterized in that the optical fiber or the optical fiber core wire is passed through liquid nitrogen to be cooled and then coated with a resin.