JP2004359513A - Method and apparatus for curing coating of optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the production cost of an optical fiber without massively consuming the expensive air in a clean room, by conducting an ultraviolet irradiation process, in which an ultraviolet-curing resin is cured, in an apparatus of a simple constitution. <P>SOLUTION: The method for reducing the production cost of an optical fiber is a curing method for an optical fiber, wherein a pipe 7 transmitting an ultraviolet ray is arranged in an ultraviolet irradiation furnace 4 installed in a clean room 3, an optical fiber strand 1 is made to pass through the inside of the pipe 7, and the ultraviolet-curing resin coating of the optical fiber strand 1 is cured during the passing of the optical fiber 1 through the inside of a pipe 7. The air in the clean room 3 is made to flow into the inside of the pipe 7, and the air outside the clean room 3 is made to flow into the ultraviolet irradiation furnace 4 as a clean air having a clean class of ≤300,000 to cool the inside of the ultraviolet irradiation furnace 4 and is exhausted to the outside of the clean room 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for coating and curing an optical fiber, and in particular, irradiates ultraviolet rays while the optical fiber passes through a pipe provided in an ultraviolet irradiation apparatus installed in a clean room, and cures the ultraviolet curing resin of the optical fiber. An optical fiber coating curing method and apparatus for curing a coating.
[0002]
[Prior art]
The general method of manufacturing optical fibers is to heat and melt an optical fiber preform in a drawing furnace, spin a bare optical fiber, cool it naturally or cool it with a cooling device, and then cool the cooled bare optical fiber with resin. The ultraviolet-curing resin or the thermosetting resin is coated with a coating die, and the ultraviolet-curing resin or the thermosetting resin is irradiated with ultraviolet light or heated in a curing furnace to be cured.
[0003]
The optical fiber coated with the ultraviolet curing resin or the thermosetting resin is guided between the capstan wheel and the capstan belt via the guide roller, the spinning speed is controlled, and the winding device winds the optical fiber on the bobbin. Taken.
[0004]
FIG. 2 is a diagram schematically showing an optical fiber coating and curing apparatus in a conventional optical fiber manufacturing apparatus. The optical fiber coating / curing apparatus comprises an ultraviolet irradiation furnace 24, in which an ultraviolet light emitting lamp 25, a reflecting mirror 26 for irradiating ultraviolet light emitted from the ultraviolet light emitting lamp 25 to an ultraviolet curing resin adhered to the surface of the optical fiber 21 and a light. It has a pipe 27 that passes the fiber strand 21 in the axial direction and transmits ultraviolet rays, and is installed in the clean room 23.
[0005]
The pipe 27 that transmits ultraviolet light is formed of a quartz tube, penetrates the housing of the ultraviolet irradiation furnace 24, and has one end opened in the clean room 23. The other end of the pipe 27 joins an exhaust pipe 29 described below via a volatile component exhaust pipe 32 and an air volume adjusting valve 33, and these constitute an exhaust line for exhausting gas exhausted from the optical fiber coating and curing device. ing.
[0006]
From one end (upper end) of the pipe 27, an optical fiber strand 21 which is spun by a drawing furnace (not shown) and whose surface is coated with an ultraviolet curable resin is introduced, passes through the inside of the pipe 27 in the axial direction, and the other end (lower end) ) Again into the clean room 23 and fed to the next step by a guide roller (not shown).
[0007]
In the ultraviolet irradiation furnace 24, clean air in the clean room 23 is supplied from an air supply pipe 28, and the furnace wall, the ultraviolet light emitting lamp 25, the reflecting mirror 26, the pipe 27, a transformer for driving the ultraviolet light emitting lamp 25, a magnetron, etc. After being cooled, the air is exhausted to the outside of the clean room 23 by an exhaust fan 31 via an exhaust pipe 29 and an air flow regulating valve 30, and these constitute a cooling line for cooling the optical fiber coating and curing device.
[0008]
When ultraviolet light emitted from the ultraviolet light emitting lamp 25 is applied to the optical fiber 21 passing through the pipe 27 by the reflecting mirror 26, the ultraviolet curing resin applied to the surface of the optical fiber is cured. When the ultraviolet-curable resin is cured, volatile components evaporate from the ultraviolet-curable resin, and the heat generated when the ultraviolet light emitting lamp 25 emits light causes the ultraviolet irradiation furnace 24, the reflecting mirror 26, and the pipe 27 to become high temperature, and the optical fiber The UV curable resin applied to 21 also has a high temperature.
[0009]
If volatile components evaporated from the solvent of the ultraviolet curable resin are discharged into the clean room 23, the clean room is contaminated and the working environment is deteriorated. Also, when the coating material of the optical fiber is heated to a high temperature, the ultraviolet curable resin is scorched and sent to the next manufacturing process in that state, for example, when the coating material comes into contact with a hard guide roller, irregularities are formed on the surface of the coating material. This may cause damage or peeling of the ultraviolet curable resin from the optical fiber core.
[0010]
Therefore, in the ultraviolet curing step, it is necessary to cool the optical fiber to prevent the coating of the optical fiber from becoming high temperature and to protect the ultraviolet irradiation furnace 24 and the pipe 27 from high temperature. Further, it is necessary to discharge volatile components that evaporate from the ultraviolet curable resin to outside the clean room.
[0011]
In the conventional example shown in FIG. 2, as described above, the clean air in the clean room 23 is taken in from one end of each of the ultraviolet irradiation furnace 24 and the pipe 27, and the ultraviolet light emitting lamp 25, the reflecting mirror 26, The pipe 27 and the like are cooled by a cooling line, and volatile components evaporating from the ultraviolet curable resin are discharged outside the clean room 23 by an exhaust line.
[0012]
Further, in an ultraviolet irradiation furnace used for manufacturing an optical fiber or the like, Patent Document 1 discloses an air cooling method and an air cooling device for preventing a temporal deterioration of an ultraviolet irradiation intensity.
[0013]
An air cooling device used in the air cooling method disclosed in Patent Document 1 is a duct for circulating cooling air in an ultraviolet irradiation furnace including an ultraviolet light emitting lamp, and a reflecting mirror for guiding ultraviolet light emitted from the ultraviolet light emitting lamp to an optical fiber. Equipped with a cooling device that cools the air after cooling the irradiation furnace, a filter that removes dust in the air-cooled air, and an air-cooled air circulation device. Cooling and circulating clean air prevents UV irradiation intensity from deteriorating over time. And extend the life of the filter.
[0014]
[Patent Document 1]
JP-A-4-65333
[Problems to be solved by the invention]
When curing the UV curable resin coating of the optical fiber, the volatile components such as the UV curable resin solvent generated in the UV irradiation furnace to cool the UV light emitting lamps, reflectors, pipes, etc. in the UV irradiation furnace In the above-described conventional example using air in the clean room to discharge gas, a large amount of expensive clean air in the clean room is consumed, and the air after cooling is exhausted to the outside of the clean room. Increases manufacturing costs.
[0016]
Further, in the air cooling method and the air cooling device as described in Patent Document 1, since the air in the ultraviolet irradiation furnace is circulated and used, the problems of the conventional example can be solved to some extent. A dedicated air cooling device must be provided to absorb the heat generated inside the device, which makes the device complicated, requires a large amount of equipment cost, requires a large amount of maintenance cost, and increases the manufacturing cost of the optical fiber.
[0017]
The present invention has been made in view of the above circumstances, and has an object to reduce the manufacturing cost of an optical fiber with a device having a simple configuration without consuming a large amount of air in an expensive clean room. I do.
[0018]
[Means for Solving the Problems]
The present invention provides a pipe that transmits ultraviolet light in an ultraviolet irradiation device installed in a clean room, allows an optical fiber to pass through the pipe, and cures an ultraviolet curable resin coating of the optical fiber while the optical fiber passes through the pipe. An optical fiber coating and curing method in which air in a clean room is introduced into a pipe, air outside the clean room is introduced as clean air of class 300,000 or less into an ultraviolet irradiation device, and air in the ultraviolet irradiation device is introduced. Exhaust to the outside of the clean room.
[0019]
In addition, the present invention provides an ultraviolet ray irradiating device installed in a clean room, a pipe that transmits ultraviolet light, allows an optical fiber to pass through the pipe, and coats the optical fiber with an ultraviolet curable resin while the optical fiber passes through the pipe. This is an optical fiber coating curing device that cures the air.The opening inside the clean room where the air flows into the pipe and the air outside the clean room are introduced into the ultraviolet irradiation device, and the inside of the ultraviolet irradiation device is cooled and exhausted outside the clean room. And a cooling line.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram showing an optical fiber coating and curing apparatus of the present invention. The main part of the optical fiber coating and curing apparatus of the present invention comprises an ultraviolet irradiation furnace 4, and an ultraviolet light emitting lamp 5 therein, a reflecting mirror 6 for irradiating ultraviolet light emitted from the ultraviolet light emitting lamp 5 to the surface of the optical fiber 1, It has a pipe 7 that allows the fiber strand 1 to pass in the axial direction and allows ultraviolet rays to pass through, and is installed entirely in the clean room 3.
[0021]
The pipe 7 that transmits ultraviolet light is a quartz tube, and an optical fiber strand that is spun from one end (upper end) of the pipe 7 by a drawing furnace (not shown) and coated on the surface with the ultraviolet curing resin by the ultraviolet curing resin coating device 2. 1 is introduced, passes through the pipe 7 in the axial direction, is fed out again from the other end (lower end) into the clean room 3, and is fed to the next step via a guide roller (not shown).
[0022]
An air supply pipe 10 for cooling air is connected to one end of the ultraviolet irradiation furnace 4, and air outside the clean room 3 is supplied through an air supply fan 8 and a filter 9, and the ultraviolet irradiation furnace 4, the ultraviolet light emitting lamp 5, and the reflecting mirror 6 are provided. , The pipe 7 and the like are cooled, and the cooled air is discharged to the exhaust pipe 11, and is discharged to the outside of the clean room 3 via the air volume adjusting valve 12 and the exhaust fan 13.
[0023]
Here, if the air outside the clean room 3 is clean air of a class of 300,000 or less, the ultraviolet light emitting lamp 5, the reflecting mirror 6, the pipe 7, the transformer for operating the ultraviolet light emitting lamp 5 and the magnetron in the ultraviolet irradiation furnace 4 Although it is possible to cool without shortening the service life, for example, it is desirable to use clean air of about 200,000 or less through a medium-performance filter 9, for example.
[0024]
The other end (lower end) of the pipe 7, one end of which opens into the clean room 3, communicates with the volatile component exhaust pipe 14 and joins the exhaust pipe 11 via the air volume adjustment valve 15. Therefore, the air in the clean room 3 sucked from one end of the pipe 7 cools the heated optical fiber 1 and also removes the volatile component evaporated from the heated ultraviolet curable resin through the volatile component exhaust pipe 14, The volatile components are exhausted to the outside of the clean room 3 through an exhaust line formed of a pipe 11.
[0025]
In the pipe 7, the clean air (clean air) in the clean room 3 comes into contact with the uncured UV-curable resin, so the higher the degree of cleanliness, the better. Can be kept in a clean state without defects.
[0026]
An exhaust sensor 16 for detecting the flow rate and the temperature of the air exhausted from the ultraviolet irradiation furnace 4 is provided in the exhaust pipe 11 of the cooling line. The operation state of the coating and curing device is grasped, and if an abnormal state occurs, the ultraviolet irradiation furnace power supply 17 is shut off to protect the optical fiber coating and curing device.
[0027]
Although the case where the coating of the optical fiber is an ultraviolet curable resin has been described above, the present invention is also applicable to a case where the coating material is a thermosetting resin. In this case, the ultraviolet irradiation furnace may be an infrared irradiation furnace, an infrared light emitting lamp may be used instead of the ultraviolet light emitting lamp, and a pipe that transmits infrared light may be used instead of the pipe that transmits ultraviolet light.
[0028]
【The invention's effect】
As is clear from the above description, according to the present invention, a pipe that transmits ultraviolet light is provided in an ultraviolet irradiation device installed in a clean room, an optical fiber is passed through the pipe, and the optical fiber passes through the pipe. When curing the UV curable resin coating on the optical fiber, use the air outside the clean room to cool the UV irradiation device, and minimize the clean air inside the clean room to remove the volatile components of the UV curable resin generated in the pipe. Because of the limited use, a large amount of air in the expensive clean room is not consumed, and the manufacturing cost of the optical fiber can be reduced by the optical fiber coating and curing apparatus having a simple configuration.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an optical fiber coating and curing apparatus of the present invention.
FIG. 2 is a schematic configuration diagram showing a conventional optical fiber coating and curing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical fiber strand, 2 ... Coating device, 3 ... Clean room, 4 ... Ultraviolet irradiation furnace, 5 ... Ultraviolet light emission lamp, 6 ... Reflector, 7 ... Pipe, 8 ... Air supply fan, 9 ... Filter, 10 ... Supply Trachea, 11: exhaust pipe, 12: air flow control valve, 13: exhaust fan, 14: volatile component exhaust pipe, 15: air flow control valve, 16: exhaust sensor, 17: ultraviolet irradiation furnace power supply.

Claims (3)

A pipe that transmits ultraviolet light is provided in an ultraviolet irradiation device installed in a clean room, an optical fiber is passed through the pipe, and the ultraviolet curable resin coating of the optical fiber is cured while the optical fiber passes through the pipe. An optical fiber coating and curing method, wherein air in the clean room is introduced into the pipe, and air outside the clean room is introduced as clean air of class 300,000 or less into the ultraviolet irradiation device. An optical fiber coating and curing method, wherein air in the irradiation device is exhausted outside the clean room. A pipe that transmits ultraviolet light is provided in an ultraviolet irradiation device installed in a clean room, an optical fiber is passed through the pipe, and the ultraviolet curable resin coating of the optical fiber is cured while the optical fiber passes through the pipe. An optical fiber coating and curing device, wherein an opening in which air in the clean room flows into the pipe, air outside the clean room is introduced into the ultraviolet irradiation device, and the inside of the ultraviolet irradiation device is cooled. An optical fiber coating / curing apparatus having a cooling line for exhausting air outside a clean room. 3. The optical fiber coating and curing apparatus according to claim 2, further comprising: an exhaust line for exhausting the air in the pipe, and a filter that converts the air outside the clean room into air having a class of 300,000 or less.

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