JP4309569B2 - Optical fiber line quoting furnace and drawing method - Google Patents

Optical fiber line quoting furnace and drawing method Download PDF

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Publication number
JP4309569B2
JP4309569B2 JP2000372444A JP2000372444A JP4309569B2 JP 4309569 B2 JP4309569 B2 JP 4309569B2 JP 2000372444 A JP2000372444 A JP 2000372444A JP 2000372444 A JP2000372444 A JP 2000372444A JP 4309569 B2 JP4309569 B2 JP 4309569B2
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optical fiber
inert gas
nitrogen
frequency induction
furnace
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JP2002173333A (en
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真二 鈴木
佳昌 清水
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Shin Etsu Chemical Co Ltd
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    • 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
    • C03B2205/64—Induction furnaces, i.e. HF/RF coil, e.g. of the graphite or zirconia susceptor type
    • 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
    • C03B2205/70—Draw furnace insulation

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  • 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

【０００１】
【発明の属する技術分野】
本発明は、高周波誘導電流のエネルギにより光ファイバプリフォームを加熱溶融し、光ファイバを線引きするための誘導加熱炉、および光ファイバを線引きする方法に関するものである。
【０００２】
【従来の技術】
光ファイバは、光ファイバプリフォームと呼ばれるコアとクララッドからなるガラスロッドを、加熱溶融しがら延伸して線引し製造される。加熱には発熱抵抗をヒータとする電気加熱炉が使用されていた。電気加熱炉の内部は、発熱抵抗を構成するグラファイトをはじめとするカーボン部品を酸化劣化から保護するため、アルゴン等の不活性ガスで満たされている。
【０００３】
最近では、加熱炉の効率向上を企図してヒータ式の電気加熱炉に替え、比較的設備コストが低く、炉構造が簡素化される高周波誘導加熱炉が使用されるようになってきた。高周波誘導加熱炉は、炉体内部の中央部にグラファイトからなる炉心管が配置され、その周囲をとり巻くように誘導コイルが配置される。誘導コイルに流れる高周波電流により炉心管に渦電流が流れて熱を生じ、炉心管の内部に送り込まれてくるプリフォームを２０００℃以上に加熱して軟化させる。これを光ファイバに線引きする。
【０００４】
【発明が解決しようとする課題】
光ファイバの線引きのための高周波誘導加熱においては、加熱温度がかなりの高温であるため、誘導コイルに極めて高い電圧をかけ、炉体との間の電位差が非常に大きくなる。その結果、誘導コイルと炉体との間で火花放電（スパーク）を引き起こすことがある。かかる放電があると、炉体または誘導コイルに損傷が発生する。炉体は冷却のために水冷ジャケット構造になっており、炉体が損傷すると、漏れた冷却水が２０００℃以上に加熱された部材に触れ、水蒸気爆発などが起こる可能性があり、非常に危険な状態になる。
【０００５】
一方、炉心管は、アルゴン等の不活性ガスで満たされることでグラファイトが酸化劣化することから保護されている。しかし、アルゴン等の０族の不活性気体は、耐火花放電という面からすると必ずしも優れているとはいえない。図２には各種不活性ガス内で、平行平板電極間に生ずる火花電圧が示されている。図から分るように、ガス圧が極めて低い範囲を除き、大方において空気よりもアルゴンの方が火花電圧は低い。火花電圧が高い空気の主成分である窒素ガスは、酸化劣化の保護のための不活性ガスとして多用されているから、高周波誘導加熱に使用することが、一見、好都合かにみえる。
【０００６】
しかしながら、光ファイバの線引きのための高周波誘導加熱においては、炉内、特に炉心管は２０００℃以上に達するため、窒素ガスは炉心管であるグラファイトと反応し、猛毒のシアンガスを発生するという問題がある。
【０００７】
本発明は、このような問題点を解消し、劣化、損傷がなく安全面で極めて優れた光ファイバの線引用加熱炉および線引方法を提供するものである。
【０００８】
【課題を解決するための手段】
上記目的を達成するためになされた本発明を適用する光ファイバの線引用加熱炉は、実施例に対応する図１に示すとおり、高周波誘導コイル５により誘導されてグラファイト製炉心管６に流れる電流のエネルギで、送り込まれてくるプリフォーム１０を加熱し、光ファイバ１１を線引きする高周波誘導加熱炉１であって、炉体３内部の雰囲気を、炉心管６が配置される内側と高周波誘導コイル５が配置される外側に絶縁材７で分離し、該内側に向けて窒素以外の不活性ガス源に繋がる導入管１３、該外側に向けて空気よりも電気絶縁性の高い窒素、６フッ化イオウ、又はフロンの不活性ガス源に繋がる導入管１４が配設されている。
【０００９】
窒素以外の不活性ガスとしては、例えばヘリウム、ネオン、アルゴン、クリプトン、キセノンが挙げられる。空気よりも電気絶縁性の高い不活性ガス、すなわち空気よりも火花電圧の高い不活性ガスとしては、例えば窒素、６フッ化イオウ、フロンが挙げられる。
【００１０】
該内側に導入管１３から送り込まれるガスの圧力が該外側に導入管１４から送り込まれるガスの圧力より高いことが好ましい。
【００１１】
さらに好ましくは、前記窒素以外の不活性ガスがアルゴンであり、電気絶縁性の高い不活性ガスが窒素である。
【００１２】
また上記目的を達成するためになされた本発明を適用する光ファイバの線引方法は、グラファイト製炉心管に流れる高周波誘導電流のエネルギによりプリフォームを加熱して光ファイバを線引きする方法において、該炉心管が配置されている近辺を窒素以外の不活性ガス雰囲気、高周波誘導コイルが配置されている近辺を空気よりも電気絶縁性の高い不活性ガス雰囲気に保たれていることを特徴としている。
【００１３】
この光ファイバの線引方法において、前記窒素以外の不活性ガス雰囲気の圧力が、前記空気よりも電気絶縁性の高い不活性ガス雰囲気の圧力より高いことが好ましい。
【００１４】
さらにこの光ファイバの線引方法において、さらに好ましくは、前記窒素以外の不活性ガスがアルゴン、前記電気絶縁性の高い不活性ガスが窒素である。
【００１５】
上記本発明の加熱炉１を用いて本発明の方法により光ファイバ１１を線引きするとき、高周波誘導コイル５に高電圧が印加されて炉体３との間の電位差が非常に大きくなっても、高周波誘導コイル５の近辺は電気絶縁性の高い不活性ガス雰囲気に保たれているから、誘導コイル５と炉体３との間で火花放電を引き起こすことがない。その一方で、グラファイトの炉心管６をはじめとするカーボン部品は、その近辺が窒素以外の不活性ガス雰囲気に保たれているから、酸化による劣化がないと同時に、極めて高い温度になってもシアンガスが発生することはない。
【００１６】
炉体３の内部が炉心管６のある内側と高周波誘導コイル５のある外側に絶縁材７で分離されているため、外側に導入する電気絶縁性の高い不活性ガス、例えば窒素ガスは、炉心管６内のプリフォームに触れることはないので、高純度でなくても、光ファイバを劣化させることはない。
【００１７】
さらに、絶縁材外側の圧力より絶縁体内側の圧力の方が高く保たれているため、窒素ガスが炉心管内に流入しプリフォームやメニスカス部やファイバに触れることはないので、高純度の窒素ガスを使用しなくとも、光ファイバの強度を低下させることはない。さらに従来に比べ高純度のアルゴンガスの使用量が半減する。
【００１８】
【発明の実施の形態】
以下、本発明の光ファイバ線引用加熱炉を使用して本発明の光ファイバ線引方法の好適な実施の形態について、添付の図面を参照して詳細に説明する。
【００１９】
図１は、本発明を適用する光ファイバ線引用加熱炉の一実施例の断面図が示してある。図に示すとおり、光ファイバ線引用加熱炉は高周波誘導加熱炉１からなるもので、中央の上部から送り込まれてくる光ファイバプリフォーム１０を加熱して光ファイバ１１を線引きし、下部から出す構造となっている。
【００２０】
高周波誘導加熱炉１の炉体３は、外周囲が水冷ジャケット構造となっており、その内部がセラミックスからなる絶縁材の筒７により仕切られている。筒７の周囲、すなわち炉体３の内部の筒７により仕切られた外側は、高周波誘導コイル５が巻かれている。高周波誘導コイル５が配置されているこの外側に向けて、炉体３を貫通して窒素ガスのボンベ（図示省略）に繋がる導入管１４が挿入され、開閉弁のついた排気管１６が配管されている。炉体３の内部の筒７により仕切られた内側は、中央部にグラファイトからなる炉心管６が配置され、筒７と炉心管６との間はグラファイト断熱材８が詰め込まれる。炉心管６および断熱材８が配置されているこの内側に向けて、炉体３を貫通してアルゴンガスのボンベ（図示省略）に繋がる導入管１３が挿入され、開閉弁のついた排気管１７が配管されている。
【００２１】
この他、炉体３の上部には図示を省略したプリフォームの吊下げ送り機構から送られてくるプリフォーム１０を炉体３の内部に導く口金２１、下部には光ファイバ１１が通る孔のあるオリフィス板を備えた風防筒２２が配置され、光ファイバ１１は図示を省略した光ファイバ巻取り機構に到る。
【００２２】
この高周波誘導加熱炉１で、プリフォームを炉心管６の中程まで送り込んでおき、導入管１４から窒素ガスを炉体３の内部の筒７により仕切られた外側に導入し、導入管１３からアルゴンガスを内側に導入し、夫々ガス流を流し続ける。高周波誘導コイル５に高周波電流を流し炉心管６の温度を上げる。プリフォーム１０の溶融温度まで達したら光ファイバ１１を引き出し巻き取ってゆくことで光ファイバの線引がなされる。
【００２３】
上記の高周波誘導加熱炉で、本発明の光ファイバの線引方法を実施した例について以下に示す。
【００２４】
絶縁材の筒７の内側にアルゴンガスを１０Ｌ／Ｍｉｎ導入し、外気の差圧が３０Ｐａになるように排気量を調整し、誘導コイル雰囲気に窒素ガス５Ｌ／Ｍｉｎ導入して、外気との差圧が２０Ｐａになる様に排気量を調整し、筒７の外側のガス圧より内側のガス圧力の方を高く保った。
【００２５】
外径６０ｍｍ、長さ８００ｍｍの光ファイバ用プリフォームから、炉心管の表面温度を約２０５０℃、線速８００ｍｍ／ｍｉｎで線引きを行い、１２５μｍ、長さ１８０ｋｍのシングルモード光ファイバを得た。このファイバをスクリーニングテスターで１％スクリーニングを実施したところ、一度も破断は起こらなかった。また、線引き終了後、炉内を目視検査したが誘導コイルと炉体間にスパークが発生した痕跡は無かった。
【００２６】
【発明の効果】
以上詳細に説明したとおり、本発明の光ファイバの線引用加熱炉は、グラファイトの炉心管が劣化することがなく、しかも高周波誘導コイルと炉体との間で火花放電を引き起こすことがないから、コイルや炉体を損傷することがない。したがって、炉体の損傷部分から水漏れして水蒸気爆発などが発生することを事前に予防できる。また加熱炉が極めて高い温度になっても、その内に配置されているカーボン部品からシアンガスが発生することがなく、この面からも安全を確保できる。
【図面の簡単な説明】
【図１】本発明を適用する光ファイバ線引用加熱炉の実施例の断面図である。
【図２】各種不活性ガスのガス圧と火花放電を発生する電圧の関係を示す図である。
【符号の説明】
１は高周波誘導加熱炉、３は炉体、５は高周波誘導コイル、６は炉心管、７は筒、８は断熱材、１０はプリフォーム、１１は光ファイバ、１３・１４は導入管、１６・１７は排気管、２１は口金、２２は風防筒である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction heating furnace for heating and melting an optical fiber preform with the energy of a high-frequency induction current to draw the optical fiber, and a method for drawing the optical fiber.
[0002]
[Prior art]
An optical fiber is manufactured by drawing a glass rod made of a core and clalad called an optical fiber preform, while heating and melting the glass rod. An electric heating furnace using a heating resistor as a heater has been used for heating. The inside of the electric heating furnace is filled with an inert gas such as argon in order to protect carbon parts such as graphite constituting the heat generating resistance from oxidative deterioration.
[0003]
Recently, in order to improve the efficiency of the heating furnace, a high-frequency induction heating furnace having a relatively low equipment cost and a simplified furnace structure has been used instead of a heater type electric heating furnace. In a high-frequency induction heating furnace, a furnace core tube made of graphite is disposed at the central portion inside the furnace body, and an induction coil is disposed so as to surround the periphery thereof. Due to the high-frequency current flowing through the induction coil, an eddy current flows through the core tube to generate heat, and the preform fed into the core tube is heated to 2000 ° C. or higher and softened. This is drawn to an optical fiber.
[0004]
[Problems to be solved by the invention]
In high-frequency induction heating for drawing an optical fiber, the heating temperature is quite high. Therefore, an extremely high voltage is applied to the induction coil, and the potential difference with the furnace body becomes very large. As a result, spark discharge (spark) may be caused between the induction coil and the furnace body. When such a discharge occurs, the furnace body or the induction coil is damaged. The furnace body has a water-cooled jacket structure for cooling, and if the furnace body is damaged, the leaked cooling water may touch a member heated to 2000 ° C or higher, causing a steam explosion, which is extremely dangerous. It becomes a state.
[0005]
On the other hand, the core tube is protected from oxidative deterioration of graphite by being filled with an inert gas such as argon. However, group 0 inert gases such as argon are not necessarily excellent in terms of spark discharge. FIG. 2 shows spark voltages generated between parallel plate electrodes in various inert gases. As can be seen, the spark voltage is much lower for argon than for air, except in the very low range of gas pressure. Nitrogen gas, which is the main component of air with a high spark voltage, is frequently used as an inert gas for protection against oxidative degradation, so it seems convenient to use it for high-frequency induction heating.
[0006]
However, in high-frequency induction heating for optical fiber drawing, the furnace, particularly the furnace core tube, reaches 2000 ° C. or more, so that nitrogen gas reacts with graphite, which is the furnace core tube, and generates extremely toxic cyan gas. is there.
[0007]
The present invention solves such problems, and provides an optical fiber line-quoting heating furnace and a drawing method that are excellent in safety without deterioration and damage.
[0008]
[Means for Solving the Problems]
An optical fiber line citation heating furnace to which the present invention is applied to achieve the above object is shown in FIG. 1 corresponding to the embodiment, and is a current that is induced by a high frequency induction coil 5 and flows into a graphite furnace tube 6. The high-frequency induction heating furnace 1 for heating the preform 10 that is fed with the energy and drawing the optical fiber 11, the atmosphere inside the furnace body 3, and the high-frequency induction coil inside the furnace core tube 6 is disposed. outwardly 5 are arranged apart min insulating material 7, introduction pipe 13 leading to the inert gas source other than nitrogen towards the inner, nitrogen high electrical insulating properties than air toward the outer side, hexafluoride An introduction pipe 14 connected to an inert gas source of sulfur or chlorofluorocarbon is provided.
[0009]
Examples of the inert gas other than nitrogen include helium, neon, argon, krypton, and xenon. Examples of the inert gas having a higher electrical insulation than air, that is, the inert gas having a spark voltage higher than that of air, include nitrogen, sulfur hexafluoride, and Freon.
[0010]
The pressure of the gas sent from the introduction pipe 13 to the inside is preferably higher than the pressure of the gas sent from the introduction pipe 14 to the outside.
[0011]
More preferably, the inert gas other than nitrogen is argon, and the inert gas having high electrical insulation is nitrogen.
[0012]
An optical fiber drawing method to which the present invention is applied to achieve the above object is a method of drawing an optical fiber by heating a preform with energy of a high-frequency induction current flowing in a graphite furnace core tube. An inert gas atmosphere other than nitrogen is maintained in the vicinity where the core tube is disposed, and an inert gas atmosphere having a higher electrical insulation than air is maintained in the vicinity where the high frequency induction coil is disposed.
[0013]
In this optical fiber drawing method, it is preferable that the pressure of the inert gas atmosphere other than the nitrogen is higher than the pressure of the inert gas atmosphere having higher electrical insulation than the air.
[0014]
Further, in this optical fiber drawing method, more preferably, the inert gas other than nitrogen is argon, and the inert gas having high electrical insulation is nitrogen.
[0015]
When the optical fiber 11 is drawn by the method of the present invention using the heating furnace 1 of the present invention, even if a high voltage is applied to the high frequency induction coil 5 and the potential difference with the furnace body 3 becomes very large, Since the vicinity of the high frequency induction coil 5 is maintained in an inert gas atmosphere with high electrical insulation, no spark discharge is caused between the induction coil 5 and the furnace body 3. On the other hand, the carbon parts such as the graphite furnace tube 6 are maintained in an inert gas atmosphere other than nitrogen, so that they are not deteriorated due to oxidation, and at the same time, cyanide gas even at extremely high temperatures. Will not occur.
[0016]
Since the inside of the furnace body 3 is separated by an insulating material 7 on the inside where the core tube 6 is located and the outside where the high frequency induction coil 5 is located, an inert gas having high electrical insulation, for example, nitrogen gas introduced to the outside, Since the preform in the tube 6 is not touched, the optical fiber is not deteriorated even if the purity is not high.
[0017]
Furthermore, since the pressure inside the insulator is kept higher than the pressure outside the insulating material, the nitrogen gas does not flow into the furnace core tube and touch the preform, meniscus part, or fiber. Even if not used, the strength of the optical fiber is not lowered. Furthermore, the amount of high-purity argon gas used is halved compared to the conventional case.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of an optical fiber drawing method of the present invention using an optical fiber wire reference heating furnace of the present invention will be described in detail with reference to the accompanying drawings.
[0019]
FIG. 1 is a cross-sectional view of an embodiment of an optical fiber line reference heating furnace to which the present invention is applied. As shown in the figure, the optical fiber line reference heating furnace is composed of a high-frequency induction heating furnace 1, and a structure in which the optical fiber preform 10 fed from the center upper part is heated to draw the optical fiber 11 and is taken out from the lower part. It has become.
[0020]
The furnace body 3 of the high-frequency induction heating furnace 1 has a water-cooled jacket structure on the outer periphery, and the inside thereof is partitioned by a cylinder 7 made of an insulating material made of ceramics. A high frequency induction coil 5 is wound around the cylinder 7, that is, on the outside partitioned by the cylinder 7 inside the furnace body 3. To this outside where the high-frequency induction coil 5 is disposed, an introduction pipe 14 that passes through the furnace body 3 and leads to a nitrogen gas cylinder (not shown) is inserted, and an exhaust pipe 16 with an on-off valve is piped. ing. A furnace core tube 6 made of graphite is disposed in the center of the inside of the furnace body 3 partitioned by the cylinder 7, and a graphite heat insulating material 8 is packed between the cylinder 7 and the furnace core tube 6. An introduction pipe 13 that passes through the furnace body 3 and leads to an argon gas cylinder (not shown) is inserted toward the inside where the core tube 6 and the heat insulating material 8 are arranged, and an exhaust pipe 17 with an on-off valve. Is piped.
[0021]
In addition, the upper part of the furnace body 3 has a base 21 for guiding the preform 10 sent from a preform feed mechanism (not shown) to the interior of the furnace body 3, and a hole through which the optical fiber 11 passes in the lower part. A windshield cylinder 22 having an orifice plate is disposed, and the optical fiber 11 reaches an optical fiber winding mechanism (not shown).
[0022]
In this high-frequency induction heating furnace 1, the preform is fed to the middle of the core tube 6, nitrogen gas is introduced from the introduction pipe 14 to the outside partitioned by the cylinder 7 inside the furnace body 3, Argon gas is introduced inside, and the gas flow continues to flow. A high frequency current is passed through the high frequency induction coil 5 to raise the temperature of the core tube 6. When the melting temperature of the preform 10 is reached, the optical fiber 11 is drawn and wound up to draw the optical fiber.
[0023]
An example of carrying out the optical fiber drawing method of the present invention in the above-described high frequency induction heating furnace will be described below.
[0024]
Argon gas is introduced at 10 L / Min inside the cylinder 7 of the insulating material, the exhaust amount is adjusted so that the differential pressure of the outside air is 30 Pa, and nitrogen gas 5 L / Min is introduced into the induction coil atmosphere. The displacement was adjusted so that the pressure was 20 Pa, and the inner gas pressure was kept higher than the outer gas pressure of the cylinder 7.
[0025]
Drawing was performed from an optical fiber preform having an outer diameter of 60 mm and a length of 800 mm at a core tube surface temperature of about 2050 ° C. and a linear velocity of 800 mm / min to obtain a single-mode optical fiber having a length of 125 μm and a length of 180 km. When this fiber was screened with a screening tester at 1%, no breakage occurred. Further, after the drawing was completed, the inside of the furnace was visually inspected, but there was no evidence that a spark occurred between the induction coil and the furnace body.
[0026]
【The invention's effect】
As described in detail above, the optical fiber line citation heating furnace of the present invention does not deteriorate the graphite core tube, and does not cause spark discharge between the high frequency induction coil and the furnace body. The coil and furnace body will not be damaged. Therefore, it is possible to prevent in advance the occurrence of a water vapor explosion due to water leakage from the damaged part of the furnace body. Even when the temperature of the heating furnace becomes extremely high, cyan gas is not generated from the carbon components disposed therein, and safety can be secured from this aspect.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of an optical fiber line reference heating furnace to which the present invention is applied.
FIG. 2 is a diagram showing a relationship between gas pressures of various inert gases and voltages for generating spark discharge.
[Explanation of symbols]
1 is a high-frequency induction heating furnace, 3 is a furnace body, 5 is a high-frequency induction coil, 6 is a core tube, 7 is a cylinder, 8 is a heat insulating material, 10 is a preform, 11 is an optical fiber, 13 and 14 are introduction pipes, 16 17 is an exhaust pipe, 21 is a base, and 22 is a windshield.

Claims (6)

高周波誘導コイルにより誘導されてグラファイト製炉心管に流れる電流のエネルギで、送り込まれてくるプリフォームを加熱し、光ファイバを線引きする高周波誘導加熱炉であって、炉体内部の雰囲気を、該炉心管が配置される内側と該高周波誘導コイルが配置される外側に絶縁材で分離し、該内側に向けて窒素以外の不活性ガス源に繋がる導入管、該外側に向けて空気よりも電気絶縁性の高い窒素、６フッ化イオウ、又はフロンの不活性ガス源に繋がる導入管が配設されたことを特徴とする光ファイバの線引用加熱炉。A high-frequency induction heating furnace that heats a preform that is fed with current energy that is induced by a high-frequency induction coil and flows through a graphite core tube, and draws an optical fiber. outwardly inside and said high frequency induction coil tubes are arranged are arranged apart min insulating material, inlet tube leading to the inert gas source other than nitrogen towards the inner, electrically insulating than air toward the outer A line citation heating furnace for optical fibers, characterized in that an introduction pipe connected to an inert gas source of nitrogen, sulfur hexafluoride, or chlorofluorocarbon is provided . 該内側に導入管から送り込まれるガスの圧力が該外側に導入管から送り込まれるガスの圧力より高いことを特徴とする請求項１に記載の光ファイバの線引用加熱炉。    2. The optical fiber line reference heating furnace according to claim 1, wherein the pressure of the gas sent from the introduction pipe to the inside is higher than the pressure of the gas sent from the introduction pipe to the outside. 前記窒素以外の不活性ガスがアルゴンであり、電気絶縁性の高い不活性ガスが窒素であることを特徴とする請求項１または２に記載の光ファイバの線引用加熱炉。    The optical fiber line-quoted heating furnace according to claim 1 or 2, wherein the inert gas other than nitrogen is argon, and the inert gas having high electrical insulation is nitrogen. グラファイト製炉心管に流れる高周波誘導電流のエネルギによりプリフォームを加熱して光ファイバを線引きする方法において、該炉心管が配置されている近辺を窒素以外の不活性ガス雰囲気、高周波誘導コイルが配置されている近辺を空気よりも電気絶縁性の高い不活性ガス雰囲気に保たれていることを特徴とする光ファイバの線引方法。    In a method of drawing an optical fiber by heating a preform with energy of a high-frequency induction current flowing in a graphite furnace core tube, an inert gas atmosphere other than nitrogen and a high-frequency induction coil are disposed in the vicinity of the furnace core tube. A method of drawing an optical fiber, characterized in that an inert gas atmosphere having a higher electrical insulation than air is maintained in the vicinity. 前記窒素以外の不活性ガス雰囲気の圧力が、前記空気よりも電気絶縁性の高い不活性ガス雰囲気の圧力より高いことを特徴とする請求項４に記載の光ファイバの線引方法。    The optical fiber drawing method according to claim 4, wherein a pressure of an inert gas atmosphere other than nitrogen is higher than a pressure of an inert gas atmosphere having higher electrical insulation than the air. 前記窒素以外の不活性ガスがアルゴン、前記電気絶縁性の高い不活性ガスが窒素であることを特徴とする請求項４または５に記載の光ファイバの線引方法。    The optical fiber drawing method according to claim 4 or 5, wherein the inert gas other than nitrogen is argon, and the inert gas having high electrical insulation is nitrogen.
JP2000372444A 2000-12-07 2000-12-07 Optical fiber line quoting furnace and drawing method Expired - Fee Related JP4309569B2 (en)

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CN103304135B (en) * 2013-07-05 2015-01-21 江苏法尔胜光子有限公司 Optical fiber drawing method for large-diameter optical fiber preform rod
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