JP3287615B2 - Optical fiber drawing method - Google Patents

Optical fiber drawing method

Info

Publication number
JP3287615B2
JP3287615B2 JP26841192A JP26841192A JP3287615B2 JP 3287615 B2 JP3287615 B2 JP 3287615B2 JP 26841192 A JP26841192 A JP 26841192A JP 26841192 A JP26841192 A JP 26841192A JP 3287615 B2 JP3287615 B2 JP 3287615B2
Authority
JP
Japan
Prior art keywords
furnace
optical fiber
furnace tube
chamber
gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP26841192A
Other languages
Japanese (ja)
Other versions
JPH06115968A (en
Inventor
久 小相澤
伸昭 折田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
THE FURUKAW ELECTRIC CO., LTD.
Original Assignee
THE FURUKAW ELECTRIC CO., LTD.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by THE FURUKAW ELECTRIC CO., LTD. filed Critical THE FURUKAW ELECTRIC CO., LTD.
Priority to JP26841192A priority Critical patent/JP3287615B2/en
Publication of JPH06115968A publication Critical patent/JPH06115968A/en
Application granted granted Critical
Publication of JP3287615B2 publication Critical patent/JP3287615B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/029—Furnaces therefor
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2205/00—Fibre drawing or extruding details
    • C03B2205/60—Optical fibre draw furnaces
    • C03B2205/62—Heating means for drawing
    • C03B2205/63—Ohmic resistance heaters, e.g. carbon or graphite resistance heaters
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2205/00—Fibre drawing or extruding details
    • C03B2205/60—Optical fibre draw furnaces
    • C03B2205/90—Manipulating the gas flow through the furnace other than by use of upper or lower seals, e.g. by modification of the core tube shape or by using baffles
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2205/00—Fibre drawing or extruding details
    • C03B2205/60—Optical fibre draw furnaces
    • C03B2205/90—Manipulating the gas flow through the furnace other than by use of upper or lower seals, e.g. by modification of the core tube shape or by using baffles
    • C03B2205/91—Manipulating the gas flow through the furnace other than by use of upper or lower seals, e.g. by modification of the core tube shape or by using baffles by controlling the furnace gas flow rate into or out of the furnace
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2205/00—Fibre drawing or extruding details
    • C03B2205/60—Optical fibre draw furnaces
    • C03B2205/90—Manipulating the gas flow through the furnace other than by use of upper or lower seals, e.g. by modification of the core tube shape or by using baffles
    • C03B2205/98—Manipulating the gas flow through the furnace other than by use of upper or lower seals, e.g. by modification of the core tube shape or by using baffles using annular gas inlet distributors

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は、光ファイバ母材を加熱
溶融して光ファイバを線引きする光ファイバ線引き方法
に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber drawing method for drawing an optical fiber by heating and melting an optical fiber preform.

【０００２】[0002]

【従来の技術】光ファイバ母材を加熱溶融して光ファイ
バを線引きするための光ファイバ線引き加熱炉は、光フ
ァイバの強度，光ファイバの外径変動や伝送ロスに影響
を与えることが知られている。2. Description of the Related Art An optical fiber drawing heating furnace for drawing an optical fiber by heating and melting an optical fiber preform is known to affect the strength of the optical fiber, the change in the outer diameter of the optical fiber, and the transmission loss. ing.

【０００３】図４は、従来の光ファイバ線引き加熱炉の
構成を示したものである。該光ファイバ線引き加熱炉に
おいては、加熱すべき光ファイバ母材（図示せず）を挿
入するための炉心管１を備え、該炉心管１は炉体２の中
央を貫通するようにして設けられている。炉体２内で炉
心管１の外周には、ヒータ３が配置されている。炉体２
内には、その内壁に沿って断熱材４が配置されている。FIG. 4 shows a configuration of a conventional optical fiber drawing heating furnace. The optical fiber drawing heating furnace includes a furnace tube 1 for inserting an optical fiber preform (not shown) to be heated, and the furnace tube 1 is provided so as to pass through the center of the furnace body 2. ing. A heater 3 is arranged inside the furnace body 2 around the furnace tube 1. Furnace body 2
Inside, the heat insulating material 4 is arranged along the inner wall.

【０００４】炉体２の下部には、炉心管１の外で炉体２
内の加熱室５に連通するガス供給口６が設けられてい
る。該ガス供給口６には、バルブ７及びマスフローコン
トローラ８を介して不活性ガスが供給されるようになっ
ている。In the lower part of the furnace body 2, the furnace body 2 is provided outside the furnace tube 1.
A gas supply port 6 communicating with a heating chamber 5 in the inside is provided. An inert gas is supplied to the gas supply port 6 via a valve 7 and a mass flow controller 8.

【０００５】炉体２の上部には、加熱室５内のガスを排
気するガス排気口９が設けられている。ガス排気口９に
は、バルブ１０および圧力計１１を介して真空引きポン
プ１２が接続され、加熱室５内の真空引きを行うように
なっている。A gas exhaust port 9 for exhausting gas in the heating chamber 5 is provided at an upper portion of the furnace body 2. A vacuum pump 12 is connected to the gas exhaust port 9 via a valve 10 and a pressure gauge 11 so as to evacuate the heating chamber 5.

【０００６】炉心管１に対応して炉体２の下には炉体延
長筒体１３が設けられ、該炉体延長筒体１３の上下には
内部に不活性ガスを吹き出すガス供給口１４，１５が設
けられている。ガス供給口１４には、バルブ１６及びマ
スフローコントローラ１７を介して不活性ガスが供給さ
れるようになっている。同様に、ガス供給口１５には、
バルブ１８及びマスフローコントローラ１９を介して不
活性ガスが供給されるようになっている。ガス供給口１
５は、炉体延長筒体１３の下部からの大気の流入を防止
するためのものである。炉心管１の下部と炉体延長筒体
１３の上部に跨がってこれらの内部には、筒状のフロー
ガイド２０が設けられ、ガス供給口１４から供給される
不活性ガスの向きを炉心管１の軸心に沿って流れるよう
に方向変換するようになっている。A furnace body extension cylinder 13 is provided below the furnace body 2 corresponding to the furnace tube 1, and gas supply ports 14 for blowing an inert gas into the inside of the furnace body extension cylinder 13 above and below the furnace body extension cylinder 13. 15 are provided. An inert gas is supplied to the gas supply port 14 via a valve 16 and a mass flow controller 17. Similarly, the gas supply port 15
An inert gas is supplied via the valve 18 and the mass flow controller 19. Gas supply port 1
Numeral 5 is for preventing the inflow of the atmosphere from the lower part of the furnace body extension cylinder 13. A tubular flow guide 20 is provided in the inside of the furnace core tube 1 so as to straddle the lower part of the furnace tube 1 and the upper part of the furnace body extension cylindrical body 13. The direction is changed so as to flow along the axis of the tube 1.

【０００７】炉心管１の上部には、真空引き用上蓋２１
が嵌合されている。炉心管１の下部には、真空引き用下
蓋２２が嵌合されている。The upper part of the furnace tube 1 has an upper lid 21 for evacuation.
Are fitted. A lower lid 22 for evacuation is fitted to a lower portion of the furnace tube 1.

【０００８】このような光ファイバ線引き加熱炉では、
2000℃以上になるのでヒータ３としては通常カーボンヒ
ータが使用され、断熱材４としてはカーボンフェルトが
使用され、他の炉構成部品もカーボンで主に形成されて
いる。In such an optical fiber drawing heating furnace,
Since the temperature is 2000 ° C. or higher, a carbon heater is usually used as the heater 3, carbon felt is used as the heat insulating material 4, and other furnace components are mainly formed of carbon.

【０００９】ヒータ３としては、通常スリットの入った
ヒータが用いられるので、図示しない光ファイバ母材を
均一に加熱するため、且つ純度の低い断熱材４からの該
光ファイバ母材の汚染を防止するため炉心管１が設けら
れている。Since a heater having a slit is usually used as the heater 3, the optical fiber preform (not shown) is uniformly heated, and the contamination of the optical fiber preform from the low-purity heat insulating material 4 is prevented. A furnace tube 1 is provided for the purpose.

【００１０】また、炉心管１内の炉心管室２３と該炉心
管１の外で炉体２内の加熱室５とには、ガス供給口１
４，１５とガス供給口６とから別々に不活性ガスが供給
され、加熱室５に供給された不活性ガスはガス排気口９
より排気されるようになっている（特開昭５９−２１７
６４１号）。A gas supply port 1 is provided between a furnace tube chamber 23 in the furnace tube 1 and a heating chamber 5 in the furnace body 2 outside the furnace tube 1.
Inert gas is separately supplied from the gas supply ports 6, 4 and 15, and the inert gas supplied to the heating chamber 5 is supplied to the gas exhaust port 9.
(See Japanese Patent Application Laid-Open No. 59-217).
641).

【００１１】[0011]

【発明が解決しようとする課題】しかしながら、特開昭
５９−２１７６４１号公報に記載のものでは、図示しな
いが炉心管１に加熱室５に連通する多数の透孔が設けら
れていて、炉心管室２３に供給された不活性ガスがこれ
ら透孔を通って加熱室５に流れ込んで排気されるように
なっているので、加熱室５が炉心管室２３より圧力が低
く、そのため炉心管室２３に挿入される光ファイバ母材
の外径に変化がある場合、特に光ファイバ母材の外径が
小さくなった時や、該光ファイバ母材の上端の肩部が炉
心管室２３に入って来た場合、炉心管１と光ファイバ母
材との間の間隙が大きくなって、大気を炉心管室２３を
経て加熱室５内に吸引し、炉心管１，ヒータ３，断熱材
４等のカーボン製の炉構成部品が酸化消耗され、該炉構
成部品の寿命が短くなったり、光ファイバの強度が低下
したりする問題点があった。However, in the apparatus disclosed in Japanese Patent Application Laid-Open No. Sho 59-217641, although not shown, the furnace tube 1 is provided with a large number of through holes communicating with the heating chamber 5, and the furnace tube 1 Since the inert gas supplied to the chamber 23 flows into the heating chamber 5 through these through holes and is exhausted, the pressure of the heating chamber 5 is lower than that of the core tube chamber 23, and therefore, When there is a change in the outer diameter of the optical fiber preform inserted into the furnace, particularly when the outer diameter of the optical fiber preform becomes smaller, or when the shoulder at the upper end of the optical fiber preform enters the furnace tube chamber 23, When it comes, the gap between the furnace tube 1 and the optical fiber preform becomes large, and the atmosphere is sucked into the heating chamber 5 through the furnace tube chamber 23, and the furnace tube 1, the heater 3, the heat insulating material 4, etc. The furnace components made of carbon are oxidized and consumed, and the life of the furnace components is shortened. It is or, the intensity of the optical fiber has a problem of lowered.

【００１２】また、炉心管１に多数の透孔が設けられて
いない場合でも、該炉心管１は一般にカーボン製で薄い
ので、炉心管室２３内の活性な蒸気が炉心管１を透過し
て加熱室５内に入り込むことがあり、カーボン製の炉構
成部品の寿命を短くする問題点があった。Even when the furnace tube 1 is not provided with a large number of through holes, the core tube 1 is generally made of carbon and is thin, so that active steam in the furnace tube chamber 23 penetrates the furnace tube 1. There is a problem that it may enter the heating chamber 5 and shorten the life of the carbon furnace components.

【００１３】本発明の目的は、光ファイバの強度低下や
炉構成部品の寿命低下を防止できる光ファイバ線引き方
法を提供することにある。An object of the present invention is to provide an optical fiber drawing method capable of preventing a reduction in strength of an optical fiber and a reduction in the life of furnace components.

【００１４】[0014]

【課題を解決するための手段】上記の目的を達成する本
発明の手段を説明すると、本発明は加熱すべき光ファイ
バ母材を挿入するための炉心管と、前記炉心管を包囲す
る炉体と、前記炉体内で前記炉心管の外周に配置された
ヒータと、前記炉心管内の炉心管室に不活性ガスを供給
するガス供給口と、前記炉心管の外で前記炉体内の加熱
室に不活性ガスを供給するガス供給口とを備え、前記炉
心管内の前記光ファイバ母材を前記ヒータで加熱溶融さ
せ、該光ファイバ母材の加熱溶融部から光ファイバを線
引きする光ファイバ線引き方法において、前記炉心管室
と前記加熱室とをガスの流通がないように分離し、且つ
前記加熱室にはガス排気口を設けて、前記加熱室内の圧
力を前記炉心管室内の圧力より高く保持しながら前記光
ファイバの線引きをすることを特徴とする。In order to achieve the above object, the present invention will be described. According to the present invention, there is provided a furnace tube for inserting an optical fiber preform to be heated, and a furnace body surrounding the furnace tube. A heater disposed on the outer periphery of the furnace tube in the furnace, a gas supply port for supplying an inert gas to a furnace tube chamber in the furnace tube, and a heating chamber in the furnace outside the furnace tube. A gas supply port for supplying an inert gas, wherein the optical fiber preform in the furnace tube is heated and melted by the heater, and an optical fiber is drawn from a heated and fused portion of the optical fiber preform. Separating the furnace tube chamber and the heating chamber so that gas does not flow therethrough, and providing a gas exhaust port in the heating chamber to maintain the pressure in the heating chamber higher than the pressure in the furnace tube chamber. While drawing the optical fiber Characterized in that it.

【００１５】[0015]

【作用】このように、炉心管室と加熱室とをガスの流通
がないように分離し、且つ加熱室にはガス排気口を設け
て、加熱室内の圧力を炉心管室内の圧力より高く保持し
ながら光ファイバの線引きをすると、純度の低い断熱材
を収容した加熱室内のガスは加熱室のガス排気口から炉
体外に排出されることになる。As described above, the furnace tube chamber and the heating chamber are separated so that gas does not flow, and a gas exhaust port is provided in the heating chamber to maintain the pressure in the heating chamber higher than the pressure in the furnace tube chamber. When the optical fiber is drawn while the gas is being drawn, the gas in the heating chamber containing the low-purity heat insulating material is discharged out of the furnace from the gas exhaust port of the heating chamber.

【００１６】この場合には、炉心管室内に入る光ファイ
バ母材に外径変化があっても、大気は積極的には炉心管
室内に入って来ない。このため光ファイバの強度低下や
炉構成部品の寿命低下を防止できる。In this case, even if the outer diameter of the optical fiber preform entering the furnace tube chamber changes, the air does not actively enter the furnace tube room. For this reason, a decrease in the strength of the optical fiber and a decrease in the life of the furnace components can be prevented.

【００１７】また、加熱室内のガスが炉心管室内に流れ
込むのを防止でき、光ファイバの強度低下を防止するこ
とができる。Further, the gas in the heating chamber can be prevented from flowing into the furnace tube chamber, and the strength of the optical fiber can be prevented from lowering.

【００１８】更に、加熱室内の圧力を炉心管室内の圧力
より高く保持しているので、炉心管室内の活性蒸気が炉
心管を透過して加熱室内に入り込み、カーボン製の炉構
成部品の寿命を短くする問題点も回避することができ
る。Furthermore, since the pressure in the heating chamber is maintained higher than the pressure in the furnace tube chamber, the active steam in the furnace tube chamber penetrates the furnace tube and enters the heating chamber, thereby increasing the life of the carbon furnace components. The problem of shortening can also be avoided.

【００１９】[0019]

【実施例】以下、本発明の実施例を図を参照して詳細に
説明する。なお、前述した図４とた対応する部分には、
同一符号を付けて示している。DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, in the part corresponding to FIG. 4 described above,
The same reference numerals are given.

【００２０】図１は、本発明に係る光ファイバ線引き加
熱炉の第１実施例を示したものである。本実施例の光フ
ァイバ線引き加熱炉では、炉心管室２３と加熱室５とは
ガスの流通がないように分離されている。真空引き用上
蓋２１にはガス排気口２４が設けられ、該ガス排気口２
４は圧力計１１を介して真空引きポンプ１２に接続され
ている。また、ガス排気口９とバルブ１０との間にはフ
ィルタ２５が接続されている。フィルタ２５とバルブ１
０との接続部には、排気口２６がチャッキバルブ２７を
介して設けられている。排気口２６には、必要に応じて
排気用ポンプを設けることができる。FIG. 1 shows a first embodiment of an optical fiber drawing heating furnace according to the present invention. In the optical fiber drawing heating furnace of this embodiment, the furnace tube chamber 23 and the heating chamber 5 are separated so that gas does not flow. A gas exhaust port 24 is provided in the upper evacuation lid 21.
4 is connected to a vacuum pump 12 via a pressure gauge 11. Further, a filter 25 is connected between the gas exhaust port 9 and the valve 10. Filter 25 and valve 1
An exhaust port 26 is provided via a check valve 27 at a connection portion with the zero. The exhaust port 26 may be provided with an exhaust pump as needed.

【００２１】このような光ファイバ線引き加熱炉では、
炉構成部品の交換後の立ち上げ時には、図１のような状
態でバルブ７，１６，１８を閉じ、チャッキバルブ（逆
止弁）２７を閉じ、バルブ１０を開け、真空引きポンプ
１２を作動して、炉心管室２３と加熱室５との真空引き
を行う。真空引きは、圧力計１１が所定値を示すまで行
う。本実施例では、５×10-2 torr まで真空引きを行っ
た。真空引きの終了後に、炉心管室２３と加熱室５に不
活性ガスを供給して満たした。この一連の動作を数回繰
り返した。In such an optical fiber drawing heating furnace,
When starting up after replacing the furnace components, the valves 7, 16 and 18 are closed, the check valve (check valve) 27 is closed, the valve 10 is opened, and the vacuum pump 12 is operated in the state as shown in FIG. Then, the furnace tube chamber 23 and the heating chamber 5 are evacuated. The evacuation is performed until the pressure gauge 11 indicates a predetermined value. In this embodiment, the evacuation was performed to 5 × 10 -2 torr. After the evacuation was completed, the furnace tube chamber 23 and the heating chamber 5 were supplied with an inert gas to be filled. This series of operations was repeated several times.

【００２２】このように炉心管室２３と加熱室５との真
空引きと不活性ガスによるパージをすることにより、炉
構成部品に付着している水分や酸素等を除去する。この
ため炉構成部品に付着していた水分や酸素に起因するカ
ーボン製の炉構成部品の使用時における消耗を防止で
き、炉構成部品の寿命低下を防止できる。具体的には、
従来は断熱材４は６カ月に１度交換をしていたが、本発
明の場合には１年以上たっても実用レベルの劣化は生じ
ていない。また、ヒータ３は１〜２カ月に１度交換をし
ていたが、本発明の場合には３カ月以上に寿命が伸び
た。In this way, by evacuation of the furnace tube chamber 23 and the heating chamber 5 and purging with an inert gas, moisture, oxygen and the like adhering to the furnace components are removed. For this reason, it is possible to prevent wear of the carbon furnace components caused by moisture and oxygen attached to the furnace components when the furnace components are used, and to prevent a decrease in the life of the furnace components. In particular,
Conventionally, the heat insulating material 4 has been replaced once every six months. However, in the case of the present invention, the deterioration at a practical level has not occurred even after one year or more. The heater 3 was replaced once every one to two months, but in the case of the present invention, the life was extended to three months or more.

【００２３】また、10-1 torr 以上の真空引きをする
と、炉内に水漏れやリークがあった場合、真空度が上が
らない。従って、真空引きを行うたびに炉体のチェック
ができ、炉体の状態を管理できる。Further, when the vacuum is applied to 10 -1 torr or more, if water leaks or leaks in the furnace, the degree of vacuum does not increase. Therefore, the furnace body can be checked every time the evacuation is performed, and the state of the furnace body can be managed.

【００２４】光ファイバ線引き加熱炉の立ち上げ時の操
作、即ち、真空引きや不活性ガスによるパージの一連の
操作が終了したら、真空引き用上蓋２１と真空引き用下
蓋２２を外し、炉心管１内に光ファイバ母材の下部を挿
入し、ヒータ３に通電し、バルブ７，１６，１８を開
け、加熱室５内と炉心管室２３内に不活性ガスを供給
し、バルブ１０を閉じ、バルブ２７を開け、加熱室５の
ガス排気口９から排気をしつつ線引き作業を行う。この
時、加熱室５内の圧力を炉心管室２３内の圧力より50〜
100 mmＡｑ高くなるように保持した。When the operation for starting the optical fiber drawing heating furnace, that is, a series of operations of evacuation and purging with an inert gas is completed, the evacuation upper lid 21 and the evacuation lower lid 22 are removed, and the furnace tube is removed. 1, the lower part of the optical fiber preform is inserted, the heater 3 is energized, the valves 7, 16, 18 are opened, an inert gas is supplied into the heating chamber 5 and the furnace tube chamber 23, and the valve 10 is closed. , The valve 27 is opened, and a wire drawing operation is performed while exhausting gas from the gas exhaust port 9 of the heating chamber 5. At this time, the pressure in the heating chamber 5 is set to 50-
It was held so as to be 100 mmAq higher.

【００２５】このように加熱室５のガス排気口９から排
気をしつつ線引き作業を行うと、加熱室５内のガスが炉
心管１内に流れ込むのを防止できる。従って、加熱室５
内のガスが炉心管室２３内に流れ込んで光ファイバ母材
から線引きされた光ファイバにダストが付着し、該光フ
ァイバの強度が低下するのを防止することができる。実
験によると、光ファイバ心線のスクリーリングにおける
断線率が、従来に比べて10〜30％改善された。When the drawing operation is performed while the gas is exhausted from the gas exhaust port 9 of the heating chamber 5, the gas in the heating chamber 5 can be prevented from flowing into the furnace tube 1. Therefore, the heating chamber 5
It is possible to prevent the gas inside from flowing into the furnace tube chamber 23 and adhering dust to the optical fiber drawn from the optical fiber preform, thereby reducing the strength of the optical fiber. According to the experiment, the disconnection rate in the screening of the optical fiber is improved by 10 to 30% as compared with the conventional case.

【００２６】図２は、本発明に係る光ファイバ線引き加
熱炉の第２実施例を示したものである。本実施例の光フ
ァイバ線引き加熱炉では、第１実施例とは逆に、炉心管
１の上部から該炉心管１内に下向きに不活性ガスを流す
ようになっている。炉体延長筒体１３の下部には、下方
からの大気の流入を防止するため、該炉体延長筒体１３
の内部に不活性ガスを吹き出すガス供給口２８が設けら
れている。該ガス供給口２８には、バルブ２９及びマス
フローコントローラ３０を介して不活性ガスが供給され
るようになっている。FIG. 2 shows a second embodiment of the optical fiber drawing heating furnace according to the present invention. In the optical fiber drawing heating furnace of the present embodiment, contrary to the first embodiment, an inert gas flows downward from the upper part of the furnace tube 1 into the furnace tube 1. At the lower part of the furnace body extension cylinder 13, the furnace body extension cylinder 13 is provided to prevent the inflow of air from below.
Is provided with a gas supply port 28 for blowing out an inert gas. An inert gas is supplied to the gas supply port 28 via a valve 29 and a mass flow controller 30.

【００２７】しかし、加熱室５に流す不活性ガスは、第
１実施例と同様に、下から上に流すようになっている。
このガスは、暖められると浮力の関係で上昇気流が生じ
るので、その流れに沿ってガスを流した方が流れが安定
するためである。However, as in the first embodiment, the inert gas flowing into the heating chamber 5 flows from the bottom to the top.
When this gas is heated, an ascending airflow is generated due to buoyancy, so that flowing the gas along the flow stabilizes the flow.

【００２８】真空引きについては、ガスの流れる方向に
真空引きをするので、該加熱室５の真空引きは第１実施
例と同様に上方から引くが、炉心管室２３の真空引きは
下方から引くようになっている。Since the evacuation is performed in the gas flowing direction, the evacuation of the heating chamber 5 is performed from above, as in the first embodiment, but the evacuation of the furnace tube chamber 23 is performed from below. It has become.

【００２９】このため炉心管１上部は、真空引き時には
図示のように真空引き用上蓋２１で閉塞されるようにな
っている。炉心管１下部の真空引き用下蓋２２にはガス
排気口３１が設けられ、該ガス排気口３１は圧力計１１
を介して真空引きポンプ１２に接続されている。その他
の点は、第１実施例とほぼ同様に構成されている。For this reason, the upper part of the furnace tube 1 is closed by a vacuum evacuation lid 21 as shown in FIG. A gas exhaust port 31 is provided in the lower evacuation lid 22 below the furnace tube 1, and the gas exhaust port 31 is connected to the pressure gauge 11.
To the vacuum pump 12. Other points are substantially the same as those of the first embodiment.

【００３０】このような構造の光ファイバ線引き加熱炉
でも、第１実施例と同様の効果を得ることができる。With the optical fiber drawing heating furnace having such a structure, the same effect as in the first embodiment can be obtained.

【００３１】図３は、炉心管１の上部外周と炉体２との
間のシール構造の具体例を示す。即ち、炉心管１の上部
外周に対応した炉体２の部分には凹部３２が設けられ、
該凹部３２を利用して炉心管１の上部外周にはカーボン
フェルト３３が嵌合されている。この場合、カーボンフ
ェルト３３は、その内径を炉心管１の外径より多少小さ
くして該炉心管１に嵌め込まれている。該カーボンフェ
ルト３３はフェルト押さえ３４で押さえられ、ボルト３
５で締めることにより該カーボンフェルト３３がつぶさ
れ、炉心管１の上部と炉体２との間のシールがなされて
いる。図示していないが、炉心管１の下部と炉体２との
間のシールも同様にして行うことができる。FIG. 3 shows a specific example of a seal structure between the outer periphery of the upper part of the furnace tube 1 and the furnace body 2. That is, a recess 32 is provided in a portion of the furnace body 2 corresponding to the upper periphery of the furnace tube 1,
A carbon felt 33 is fitted on the outer periphery of the upper part of the furnace tube 1 using the recess 32. In this case, the inside diameter of the carbon felt 33 is slightly smaller than the outside diameter of the furnace tube 1 and is fitted into the furnace tube 1. The carbon felt 33 is held by a felt holder 34 and the bolt 3
By tightening at 5, the carbon felt 33 is crushed, and the seal between the upper part of the furnace tube 1 and the furnace body 2 is made. Although not shown, the sealing between the lower part of the furnace tube 1 and the furnace body 2 can be performed in the same manner.

【００３２】[0032]

【発明の効果】以上説明したように、本発明に係る光フ
ァイバ線引き方法では、炉心管室と加熱室とをガスの流
通がないように分離し、且つ加熱室にはガス排気口を設
けて、加熱室内の圧力を炉心管室内の圧力より高く保持
しながら光ファイバの線引きをするので、純度の低い断
熱材を収容した加熱室内のガスは加熱室のガス排気口か
ら炉体外に排出されることになり、このため加熱室内の
ガスが炉心管室内に流れ込むのを防止でき、光ファイバ
の強度低下を防止することができる。As described above, in the optical fiber drawing method according to the present invention, the furnace tube chamber and the heating chamber are separated so that gas does not flow, and the heating chamber is provided with a gas exhaust port. Since the optical fiber is drawn while keeping the pressure in the heating chamber higher than the pressure in the furnace tube chamber, the gas in the heating chamber containing the low-purity heat-insulating material is discharged from the gas exhaust port of the heating chamber to the outside of the furnace body. Therefore, the gas in the heating chamber can be prevented from flowing into the furnace tube chamber, and the strength of the optical fiber can be prevented from lowering.

【００３３】また、この場合には、炉心管室内に入る光
ファイバ母材に外径変化があっても、大気は積極的には
炉心管室内に入って来ないので、光ファイバの強度低下
や炉構成部品の寿命低下を防止することができる。In this case, even if the outer diameter of the optical fiber preform entering the core tube chamber changes, the air does not actively enter the core tube chamber. It is possible to prevent a decrease in the life of the furnace components.

【００３４】更に、加熱室内の圧力を炉心管室内の圧力
より高く保持しているので、炉心管室内の活性蒸気が炉
心管を透過して加熱室内に入り込み、カーボン製の炉構
成部品の寿命を短くする問題点も回避することができ
る。Further, since the pressure in the heating chamber is maintained higher than the pressure in the furnace tube chamber, the active steam in the furnace tube chamber penetrates the furnace tube and enters the heating chamber, thereby extending the life of the carbon component parts. The problem of shortening can also be avoided.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明に係る光ファイバ線引き加熱炉の第１実
施例の縦断面図である。FIG. 1 is a longitudinal sectional view of a first embodiment of an optical fiber drawing heating furnace according to the present invention.

【図２】本発明に係る光ファイバ線引き加熱炉の第２実
施例の縦断面図である。FIG. 2 is a longitudinal sectional view of a second embodiment of the optical fiber drawing heating furnace according to the present invention.

【図３】本発明で炉心管の上部外周と炉体との間のシー
ル構造の具体例を示す縦断面図である。FIG. 3 is a longitudinal sectional view showing a specific example of a seal structure between an upper outer periphery of a furnace tube and a furnace body in the present invention.

【図４】従来の光ファイバ線引き加熱炉の縦断面図であ
る。FIG. 4 is a longitudinal sectional view of a conventional optical fiber drawing heating furnace.

【符号の説明】[Explanation of symbols]

１ 炉心管 ２ 炉体 ３ ヒータ ４ 断熱材 ５ 加熱室 ６ ガス供給口 ７ バルブ ８ マスフローコントローラ ９ ガス排気口 １０ バルブ １１ 圧力計 １２ 真空引きポンプ １３ 炉体延長筒体 １４，１５ ガス供給口 １６ バルブ １７ マスフローコントローラ １８ バルブ １９ マスフローコントローラ ２０ フローガイド ２１ 真空引き用上蓋 ２２ 真空引き用下蓋 ２３ 炉心管室 ２４ ガス排気口 ２５ フィルタ ２６ 排気口 ２７ チャッキバルブ ２８ ガス供給口 ２９ バルブ ３０ マスフローコントローラ ３１ ガス排気口 ３２ 凹部 ３３ カーボンフェルト ３４ フェルト押さえ ３５ ボルト DESCRIPTION OF SYMBOLS 1 Furnace tube 2 Furnace 3 Heater 4 Insulation material 5 Heating chamber 6 Gas supply port 7 Valve 8 Mass flow controller 9 Gas exhaust port 10 Valve 11 Pressure gauge 12 Vacuum pump 13 Furnace extension cylinder 14, 15 Gas supply port 16 Valve Reference Signs List 17 Mass flow controller 18 Valve 19 Mass flow controller 20 Flow guide 21 Vacuum upper lid 22 Vacuum lower lid 23 Core tube chamber 24 Gas exhaust port 25 Filter 26 Exhaust port 27 Check valve 28 Gas supply port 29 Valve 30 Mass flow controller 31 Gas exhaust Mouth 32 Recess 33 Carbon felt 34 Felt retainer 35 Bolt

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭62−202836（ＪＰ，Ａ) 特開 昭60−51633（ＪＰ，Ａ) 特開 昭60−137842（ＪＰ，Ａ) 実開 昭63−27445（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.7，ＤＢ名) C03B 37/027 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-202836 (JP, A) JP-A-60-51633 (JP, A) JP-A-60-137842 (JP, A) 27445 (JP, U) (58) Field surveyed (Int. Cl. 7 , DB name) C03B 37/027

Claims (1)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】 加熱すべき光ファイバ母材を挿入するた
めの炉心管と、前記炉心管を包囲する炉体と、前記炉体
内で前記炉心管の外周に配置されたヒータと、前記炉心
管内の炉心管室に不活性ガスを供給するガス供給口と、
前記炉心管の外で前記炉体内の加熱室に不活性ガスを供
給するガス供給口とを備え、前記炉心管内の前記光ファ
イバ母材を前記ヒータで加熱溶融させ、該光ファイバ母
材の加熱溶融部から光ファイバを線引きする光ファイバ
線引き方法において、 前記炉心管室と前記加熱室とをガスの流通がないように
分離し、且つ前記加熱室にはガス排気口を設けて、前記
加熱室内の圧力を前記炉心管室内の圧力より高く保持し
ながら前記光ファイバの線引きをすることを特徴とする
光ファイバ線引き方法。1. A furnace tube for inserting an optical fiber preform to be heated, a furnace body surrounding the furnace tube, a heater arranged on an outer periphery of the furnace tube in the furnace body, and a A gas supply port for supplying an inert gas to the core tube chamber of
A gas supply port for supplying an inert gas to a heating chamber inside the furnace outside the furnace tube; heating and melting the optical fiber preform in the furnace tube with the heater to heat the optical fiber preform; An optical fiber drawing method for drawing an optical fiber from a fusion part, wherein the furnace tube chamber and the heating chamber are separated so that gas does not flow, and a gas exhaust port is provided in the heating chamber, and the heating chamber is provided. An optical fiber drawing method, wherein the optical fiber is drawn while maintaining the pressure in the furnace tube chamber higher than the pressure in the furnace tube chamber.
JP26841192A 1992-10-07 1992-10-07 Optical fiber drawing method Expired - Lifetime JP3287615B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP26841192A JP3287615B2 (en) 1992-10-07 1992-10-07 Optical fiber drawing method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP26841192A JP3287615B2 (en) 1992-10-07 1992-10-07 Optical fiber drawing method

Publications (2)

Publication Number Publication Date
JPH06115968A JPH06115968A (en) 1994-04-26
JP3287615B2 true JP3287615B2 (en) 2002-06-04

Family

ID=17458112

Family Applications (1)

Application Number Title Priority Date Filing Date
JP26841192A Expired - Lifetime JP3287615B2 (en) 1992-10-07 1992-10-07 Optical fiber drawing method

Country Status (1)

Country Link
JP (1) JP3287615B2 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5348191B2 (en) * 2011-07-08 2013-11-20 住友電気工業株式会社 Optical fiber drawing apparatus and drawing method
NL2021543B1 (en) * 2018-09-03 2020-04-30 Draka Comteq Bv Method, heating device and system for heating an elongate silica cylinder for use in the manufacturing of optical fibers.

Also Published As

Publication number Publication date
JPH06115968A (en) 1994-04-26

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