JP2009155157A - Device of producing preform for optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device of producing a preform for an optical fiber which can improve the heat efficiency of a heating furnace, and can sinter a soot preform at lower output. <P>SOLUTION: In the device where a soot preform is stored at the inside of a furnace core pipe, and is heated, so as to produce a preform for an optical fiber, a heat shield disk comprising a heat insulating material is set in the upper part of the soot preform. The heat shield disk set in the upper part of the soot preform preferably has a structure where the heat insulating material is stored in the inside of a glass vessel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical fiber preform manufacturing apparatus for efficiently performing heat insulation in a furnace core tube while maintaining the quality of the optical fiber preform.

  In order to manufacture an optical fiber preform, a porous glass particulate laminate (hereinafter referred to as a soot preform) formed by a VAD method, an OVD method, or the like is formed, and the soot preform is dehydrated and sintered. Need to be transparent. For these dehydration and transparency, a heating furnace equipped with a furnace core tube for containing a soot preform is used. FIG. 1 is a schematic configuration diagram illustrating a conventional heating furnace, in which reference numeral 1 is a soot preform, 2 is an optical fiber preform, 3 is a core tube, 4 is a dummy rod, and 6 is a heater. . Quartz glass is mainly used as the material of the core tube 3.

The soot preform is dehydrated and made transparent from the lower end to the upper end of the soot preform. At this time, the closer to the upper end, the more the heat diffuses upward, so the heating furnace output needs to be increased, and the energy cost increases. In response to this problem, in the conventional technique disclosed in Patent Document 1, a heat shield is attached to improve the thermal diffusion so as to be in contact with the upper end of the optical fiber porous preform (soot preform).
JP 2003-321235 A

However, in the prior art of Patent Document 1, a quartz plate is used as a shielding plate. However, it cannot be said that the quartz plate has a higher heat insulating effect and heat shielding effect than a heat insulating material such as carbon. The same applies to an opaque quartz plate.
Further, when a heat shield such as carbon is used, there is a concern that the quality of the base material is deteriorated due to carbon dust deteriorated by heat.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical fiber preform manufacturing apparatus that can improve the thermal efficiency of a heating furnace and can sinter a soot preform with a lower output.

In order to achieve the above object, the present invention provides an optical fiber preform manufacturing apparatus having a heating furnace in which a soot preform is accommodated in a furnace tube and heated to manufacture an optical fiber preform.
Provided is an optical fiber preform manufacturing apparatus in which a heat shield disk including a heat insulating material is installed on an upper portion of a soot preform.

  In the optical fiber preform manufacturing apparatus of the present invention, it is preferable that the heat shield disk installed on the upper portion of the soot preform has a structure in which a heat insulating material is accommodated in a glass container.

  In the optical fiber preform manufacturing apparatus of the present invention, it is preferable that the heat shield disk installed on the upper portion of the soot preform includes a carbon heat insulating material.

  In the optical fiber preform manufacturing apparatus of the present invention, it is preferable that the heat shield disk installed on the upper portion of the soot preform includes a glass wool heat insulating material.

The optical fiber preform manufacturing apparatus of the present invention has a structure in which a heat shield disk including a heat insulating material is installed on the upper portion of the soot preform. Diffusion can be suppressed, the thermal efficiency of the heating furnace can be improved, and the soot preform can be sintered at a lower output.
In addition, by sealing a heat insulating material such as a carbon heat insulating material in a quartz glass container or covering it with quartz glass, dust generation during heating of the heat insulating material can be suppressed, so that the quality of the optical fiber preform can be improved. Deterioration can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a diagram showing an embodiment of the optical fiber preform manufacturing apparatus of the present invention. An optical fiber preform manufacturing apparatus 10 according to this embodiment includes a furnace core tube 3 that houses a soot preform 1 (an optical fiber preform 2 after being transparent), a heater 4 for heating the soot preform 1, A heat shield disk 5 including a heat insulating material installed on the upper portion of the soot preform 1 is configured.

  The soot preform 1 has a dummy rod 4 provided at the upper end thereof fixed to a moving shaft (not shown), and is moved up and down in the core tube 3 by the vertical movement of the moving shaft. The relative position can be changed. The furnace core tube 3 is made of quartz glass.

  FIG. 3 is a cross-sectional view showing a first example of a heat shield disk 5 including a heat insulating material installed on the upper portion of the soot preform 1. The heat shield disk 5 of the present example accommodates a carbon heat insulating material 12 in a glass container 11 with a lid made of quartz glass, puts the glass container 11 in a sealed state, and inserts a through hole at its center into a soot. It is structured to be inserted through the dummy bar 4 of the reform 1.

  As a heat insulating material accommodated in the glass container 11, in addition to carbon heat insulating materials such as carbon fibers, inorganic fibers such as glass wool can be used.

When the heat shield disk 5 is installed on the upper portion of the soot preform 1 as shown in FIG. 2 to perform dehydration and transparency, the heat in the core tube 3 is heated when the soot preform 1 is heated by the heater 6. Can be suppressed by the heat shield disk 5, the thermal efficiency of the heating furnace of the optical fiber preform manufacturing apparatus 10 can be improved, and the soot preform 1 is sintered at a lower output to obtain a transparent optical fiber preform. 2 can be manufactured.
Further, since the heat shield disk 5 in which the heat insulating material 12 such as the carbon heat insulating material is sealed in the quartz glass container 11 can be used, dust generation at the time of heating the heat insulating material 12 can be suppressed. The deterioration of the quality of the material can be prevented. As shown in FIG. 4, when only the disk-shaped carbon heat insulating material 12 is used, dust is generated from the carbon heat insulating material 12 due to high-temperature heating, which is mixed into the optical fiber preform 2 and light. When the fiber preform is spun, the mechanical strength of the optical fiber is deteriorated to easily cause troubles such as disconnection.

FIG. 5 is a cross-sectional view showing a second example of the heat shield disk used in the present invention. The heat shield disk of this example has a structure in which the carbon heat insulating material 12 is completely enclosed in the glass container 13.
In this example, the same effect as the case where the heat shield disk 5 of FIG. 3 is used can be obtained.

Example 1
As shown in FIG. 2, a soot preform was made transparent by installing a heat shield disc in which a carbon heat insulating material was housed in a disc-shaped glass container shown in FIG. 3.
In this example, it was possible to reduce the heating furnace power by about 10% and make it transparent as compared with the case where no disk was used.
Moreover, when this transparent optical fiber preform was drawn on an optical fiber, it showed the same mechanical strength as that of the preform that did not use a heat shield disk.

(Comparative Example 1)
A heat shield disk made of the carbon heat insulating material 12 shown in FIG. 4 was installed on the upper part of the soot preform, and the soot preform was made transparent.
In this comparative example, it was possible to make the heating furnace power transparent by reducing the heating furnace power by about 10% as compared with the case where no disk was used. However, the number of occurrences of mechanical strength defects in the optical fiber obtained by drawing the transparent optical fiber preform was 20 in total.

(Example 2)
As shown in FIG. 5, a heat shielding disk including a carbon heat insulating material 12 in a disk-shaped sealed glass container is installed on the upper part of the soot preform as shown in FIG. 2, and the soot preform is made transparent. did.
In this example, it was possible to reduce the heating furnace power by about 10% and make it transparent as compared with the case where no disk was used.
Moreover, when this transparent optical fiber preform was drawn on an optical fiber, it showed the same mechanical strength as that of the preform that did not use a heat shield disk.
Ten base materials were spun using the lower opening of the spinning furnace. As a result, the number of occurrences of mechanical strength defects in the optical fiber was as good as zero.

(Example 3)
As shown in FIG. 3, a heat shield disc in which a glass wool heat insulating material was housed in a disc-shaped glass container was installed on the upper portion of the soot preform as shown in FIG. 2, and the soot preform was made transparent.
In this example, it was possible to reduce the heating furnace power by about 10% and make it transparent as compared with the case where no disk was used.
Moreover, when this transparent optical fiber preform was drawn on an optical fiber, it showed the same mechanical strength as that of the preform that did not use a heat shield disk.

It is a schematic block diagram which illustrates the conventional heating furnace. It is a schematic block diagram which shows one Embodiment of the optical fiber preform manufacturing apparatus of this invention. It is sectional drawing which shows the 1st example of a heat insulation disk. It is sectional drawing which shows the carbon disk used in the comparative example. It is sectional drawing which shows the 2nd example of a heat insulation disk.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Soot preform, 2 ... Optical fiber preform | base_material, 3 ... Core tube, 4 ... Dummy rod, 5 ... Heat insulation disk, 6 ... Heater, 10 ... Optical fiber preform manufacturing apparatus, 11 ... Glass container, 12 ... Carbon Heat-insulating material, 13 ... Glass container.

Claims (4)

In an optical fiber preform manufacturing apparatus having a heating furnace that houses a soot preform in a furnace core tube and heats to produce an optical fiber preform,
An optical fiber preform manufacturing apparatus characterized in that a heat shield disk including a heat insulating material is installed on an upper portion of a soot preform.   2. The optical fiber preform manufacturing apparatus according to claim 1, wherein the heat shield disk installed on the upper portion of the soot preform has a structure in which a heat insulating material is accommodated in a glass container.   The optical fiber preform manufacturing apparatus according to claim 1 or 2, wherein the heat shield disk installed on the upper portion of the soot preform includes a carbon heat insulating material.   The optical fiber preform manufacturing apparatus according to claim 1 or 2, wherein the heat shield disk installed on the upper portion of the soot preform includes a glass wool heat insulating material.

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