JP2009040662A - Manufacturing method of glass preform - Google Patents

Manufacturing method of glass preform Download PDF

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JP2009040662A
JP2009040662A JP2007209861A JP2007209861A JP2009040662A JP 2009040662 A JP2009040662 A JP 2009040662A JP 2007209861 A JP2007209861 A JP 2007209861A JP 2007209861 A JP2007209861 A JP 2007209861A JP 2009040662 A JP2009040662 A JP 2009040662A
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base material
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glass base
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JP2009040662A5 (en
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Yusuke Kubo
祐介 久保
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Sumitomo Electric Industries 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
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/01413—Reactant delivery systems
    • 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
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a glass preform capable of reducing as much as possible the variation of a reflection index in an axial direction. <P>SOLUTION: In the manufacturing method of the glass preform wherein a transparentized glass preform is obtained by forming a porous glass preform 5 by depositing glass fine particles at the outer periphery or the lower side of a vertically supported glass rod 2, then transparentizing by dehydrating and sintering in an operating state that the porous glass 5 is vertically supported, a clad portion 3 having a length set in a range of ≥1% and ≤25% to a length of an effective part Lx from the lower edge of the effective part Lx of the porous glass preform 5 is previously formed in a tapered shape whose outer diameter is gradually lowered toward a lower part by gradually reducing a deposition amount of the glass fine particles toward the lower side in a range of ≥1% and ≤10% to a length of other parts of the effective part Lx. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、ガラス微粒子を堆積させた多孔質ガラス母材を垂直状態で焼結して透明化されたガラス母材とするガラス母材の製造方法に関する。   The present invention relates to a method for producing a glass base material in which a porous glass base material on which glass particles are deposited is sintered in a vertical state to make a transparent glass base material.

一般に、コアとクラッドよりなる光ファイバは、光ファイバ用のガラス母材を線引きして製造される。
光ファイバ用ガラス母材は、ＶＡＤ法やＯＶＤ法などにより、バーナの火炎中に生成したガラス微粒子を石英等からなるガラスロッドの外周あるいは下側に堆積させて図４に示すようにコア部分５１とその外周のクラッド部分５２とを有した多孔質ガラス母材５３を形成し、その後、この多孔質ガラス母材５３を脱水焼結炉内のヒータ５５にて加熱して脱水・焼結して透明ガラス化することにより製造される。 In general, an optical fiber composed of a core and a clad is manufactured by drawing a glass preform for an optical fiber.
The glass base material for the optical fiber is formed by depositing glass fine particles generated in the flame of the burner by the VAD method or OVD method on the outer periphery or the lower side of a glass rod made of quartz or the like as shown in FIG. And a porous glass base material 53 having a cladding portion 52 on the outer periphery thereof, and thereafter, the porous glass base material 53 is heated by a heater 55 in a dehydration sintering furnace to be dehydrated and sintered. Manufactured by transparent vitrification.

また、多孔質ガラス母材５３を形成する際に、コア部分５１の先端位置をレーザにより測定しながら多孔質ガラス母材５３の引き上げ速度、クラッド部分５２への原料の供給量を制御し、コア部分５１とクラッド部分５２の外径比の軸方向での変動を抑えることが行われている（例えば、特許文献１参照）。   Further, when forming the porous glass base material 53, the pulling speed of the porous glass base material 53 and the supply amount of the raw material to the clad part 52 are controlled while measuring the tip position of the core part 51 with a laser. A variation in the axial direction of the outer diameter ratio between the portion 51 and the clad portion 52 is suppressed (see, for example, Patent Document 1).

特開２００３−２７７０９７号公報JP 2003-277097 A

ところで、一般に、多孔質ガラス母材の透明ガラス化は、図４に示したように多孔質ガラス母材５３の上端を固定して垂直に支持した状態のまま脱水焼結炉内にて脱水・焼結することで行われている。
この多孔質ガラス母材５３の焼結時には、多孔質ガラス母材５３の上端が固定のため、多孔質ガラス母材５３の下端側が上方へ収縮していくが、下端側ほど自重による負荷が小さくなるため、下端側では収縮に伴う外径の変化量が小さくなり、下端側の外径が相対的に大きくなる。 By the way, in general, the transparent vitrification of the porous glass base material is performed by dehydration and sintering in a dehydration sintering furnace with the upper end of the porous glass base material 53 fixed and vertically supported as shown in FIG. It is done by sintering.
At the time of sintering the porous glass base material 53, the upper end of the porous glass base material 53 is fixed, so that the lower end side of the porous glass base material 53 contracts upward. Therefore, the amount of change in the outer diameter associated with the contraction is reduced on the lower end side, and the outer diameter on the lower end side is relatively increased.

このため、上記技術によって軸方向における外径比の変動を抑えて多孔質ガラス母材５３を形成しても、焼結して透明ガラス化する際に、図５に示すように、クラッド部分５２Ａの下端側における外径Ｄ１が許容範囲を超えて太くなることがあった。その場合には、透明ガラス化したガラス母材５３Ａは、クラッド部分５２Ａとコア部分５１Ａとの比率（クラッド／コア比）が下端側で大きくなり、軸方向における屈折率分布に変動が生じ、このガラス母材５３Ａから線引きして得られた光ファイバの屈折率分布が長手方向で均一にならないという問題が発生する。   For this reason, even if the porous glass base material 53 is formed by suppressing the fluctuation of the outer diameter ratio in the axial direction by the above technique, as shown in FIG. In some cases, the outer diameter D1 on the lower end side of the plate becomes thicker than the allowable range. In that case, in the glass base material 53A made into a transparent glass, the ratio of the clad portion 52A and the core portion 51A (cladding / core ratio) becomes larger on the lower end side, and the refractive index distribution in the axial direction fluctuates. There arises a problem that the refractive index distribution of the optical fiber obtained by drawing from the glass preform 53A is not uniform in the longitudinal direction.

また、下端側が許容範囲を超えて太くなったガラス母材５３Ａは、次工程の炉に入らないなどの不具合が発生することもあり、下端を細くするために、再度加熱して軟化させて延伸するなどの余分な手間が増えるという問題もあった。   In addition, the glass base material 53A whose lower end side becomes thicker than the allowable range may cause problems such as not entering the furnace of the next process. In order to make the lower end thinner, the glass base material 53A is heated again to be softened and stretched. There was also a problem that extra work such as doing it increased.

特に、コア部分とクラッド部分の一部を有するガラスロッドの周囲に残りのクラッド部分のガラス微粒子を堆積させ、その多孔質ガラス母材を焼結する場合に、外径の不均一が生じると、クラッド／コア比の修正が困難となる。   In particular, when non-uniformity of the outer diameter occurs when depositing the glass particles of the remaining cladding part around the glass rod having a part of the core part and the cladding part, and sintering the porous glass base material, It becomes difficult to correct the cladding / core ratio.

そこで、本発明は、軸方向における屈折率分布の変動を極力低減することができるガラス母材の製造方法を提供することを目的としている。   Accordingly, an object of the present invention is to provide a method for manufacturing a glass base material that can reduce fluctuations in the refractive index distribution in the axial direction as much as possible.

（１）上記した課題を解決するために、本発明によるガラス母材の製造方法は、バーナの火炎中に生成したガラス微粒子を、垂直に支持されたガラスロッドの外周あるいは下側に堆積させて、コア部分とその外周のクラッド部分とを有した多孔質ガラス母材を形成した後、前記多孔質ガラス母材を垂直に支持した状態のまま脱水・焼結して透明ガラス化して、透明化されたガラス母材を得るガラス母材の製造方法において、
前記多孔質ガラス母材の有効部の下端から前記有効部の長さに対し１％以上２５％以下の範囲内で設定された長さ分のクラッド部分は、予め、下方に向かって徐々にガラス微粒子の堆積量を前記有効部の他の部位に対して１％以上１０％以下の範囲内で減少させて、下方に向かって徐々に外径が小さく先細り形状に形成しておくことを特徴とする。 (1) In order to solve the above-described problem, the glass base material manufacturing method according to the present invention deposits glass fine particles generated in a flame of a burner on the outer periphery or lower side of a vertically supported glass rod. After forming a porous glass base material having a core portion and a cladding portion on the outer periphery thereof, the porous glass base material is vertically supported and dehydrated and sintered to form a transparent glass, thereby making it transparent. In the manufacturing method of the glass base material which obtains the glass base material made,
The clad portion of the length set in the range of 1% to 25% with respect to the length of the effective portion from the lower end of the effective portion of the porous glass base material is gradually lowered downward in advance. The accumulation amount of the fine particles is reduced within a range of 1% to 10% with respect to the other parts of the effective portion, and the outer diameter is gradually reduced toward the lower side, and the tapered shape is formed. To do.

（２）また、上記（１）に記載のガラス母材の製造方法は、前ロットで製造されたガラス母材のクラッド部分の外径が許容値以上に大きいとき、次ロットではそれが解消されるように、前記クラッド部分の先細り形状の開始位置が、前ロットの時の開始位置よりも上方に修正されることを特徴としても良い。   (2) Further, in the glass base material manufacturing method according to the above (1), when the outer diameter of the clad portion of the glass base material manufactured in the previous lot is larger than the allowable value, it is eliminated in the next lot. As described above, the start position of the tapered shape of the clad portion may be corrected above the start position in the previous lot.

（３）また、上記（１）又は（２）に記載のガラス母材の製造方法は、前記ガラスロッドの外周あるいは下側にガラス微粒子を堆積させる工程において、前記先細り形状の部位では、前記有効部の他の部位に対してガラス微粒子を堆積させる際の嵩密度を下げることを特徴としても良い。   (3) Further, in the method for producing a glass base material according to (1) or (2) above, in the step of depositing glass fine particles on the outer periphery or the lower side of the glass rod, It is good also as reducing the bulk density at the time of depositing glass fine particles with respect to the other site | part of a part.

（４）また、上記（１）又は（２）に記載のガラス母材の製造方法は、前記ガラスロッドの外周あるいは下側にガラス微粒子を堆積させる工程において、クラッド部分の基準外径位置を、ガラスロッドの引き上げに応じて徐々に内側に移動させることにより、前記クラッド部分の先細り形状を形成することを特徴としても良い。   (4) Further, in the method for producing a glass base material according to the above (1) or (2), in the step of depositing glass fine particles on the outer periphery or the lower side of the glass rod, the reference outer diameter position of the cladding portion is set as follows: The tapered shape of the clad portion may be formed by gradually moving the glass rod inward according to the pulling up of the glass rod.

（５）また、上記（１）又は（２）に記載のガラス母材の製造方法は、前記ガラスロッドの外周あるいは下側にガラス微粒子を堆積させる工程において、クラッド部分としてガラス微粒子を吹き付けて堆積させるバーナにおける前記ガラス微粒子の原料流量を徐々に低減させることにより、前記クラッド部分の先細り形状が形成されることを特徴としても良い。 (5) Further, in the method for producing a glass base material according to (1) or (2), in the step of depositing glass fine particles on the outer periphery or the lower side of the glass rod, the glass fine particles are sprayed and deposited as a clad portion. The tapered shape of the clad portion may be formed by gradually reducing the raw material flow rate of the glass fine particles in the burner to be used.

（６）また、上記（１）又は（２）に記載のガラス母材の製造方法は、前記多孔質ガラス母材のクラッド部分の先細り形状を、機械的な研磨処理により得ることを特徴としても良い。 (6) Further, the glass base material manufacturing method according to the above (1) or (2) may be characterized in that the tapered shape of the clad portion of the porous glass base material is obtained by mechanical polishing treatment. good.

本発明によるガラス母材の製造方法によれば、透明ガラス化のために多孔質ガラス母材が脱水・焼結される時には、多孔質ガラス母材の上端が固定のため、多孔質ガラス母材の下端側が上方へ収縮していくが、下端側ほど自重による負荷が小さくなるため、下端側では収縮に伴う外径の変化量が小さくなり、下端側の外径が相対的に大きくなる。
しかし、透明ガラス化する多孔質ガラス母材は、有効部の下端から所定長さ分のクラッド部分を、予め、下方に向かって徐々に外径が縮径する先細り形状に形成しているため、外径が増大しても、下端側における外径が許容範囲を超えて太くなることを防止できる。
即ち、本発明によるガラス母材の製造方法によれば、透明ガラス化したガラス母材の外径の変動を抑えて、コア部分とクラッド部分の外径比の軸方向での変動の低減により、軸方向における屈折率分布の変動を極力低減することができる。 According to the method for manufacturing a glass base material according to the present invention, when the porous glass base material is dehydrated and sintered for transparent vitrification, the upper end of the porous glass base material is fixed. However, since the load due to its own weight decreases toward the lower end, the amount of change in the outer diameter associated with the contraction decreases on the lower end, and the outer diameter on the lower end increases relatively.
However, because the porous glass base material to be transparent vitrified is formed in a tapered shape whose outer diameter gradually decreases toward the lower part in advance, the cladding portion for a predetermined length from the lower end of the effective portion, Even if the outer diameter increases, it is possible to prevent the outer diameter on the lower end side from increasing beyond the allowable range.
That is, according to the manufacturing method of the glass base material according to the present invention, by suppressing the variation in the outer diameter of the glass base material made into a transparent glass, by reducing the variation in the axial direction of the outer diameter ratio of the core portion and the cladding portion, Variations in the refractive index distribution in the axial direction can be reduced as much as possible.

また、透明ガラス化したガラス母材の下端側が許容範囲を超えて太くなることを防止できるため、下端の外径の増大により次工程の炉に入らないなどの不具合が発生することがなく、下端を細くするために再度加熱して延伸するなどの余分な手間も不要になる。   In addition, since it is possible to prevent the lower end side of the glass base material that has become transparent glass from becoming thicker beyond the allowable range, problems such as not entering the furnace of the next process due to an increase in the outer diameter of the lower end do not occur. In order to reduce the thickness, there is no need for extra work such as heating and stretching again.

以下、本発明に係るガラス母材の製造方法の好適な実施の形態について、図面を参照して詳細に説明する。
図１は本発明に係るガラス母材の製造方法において多孔質ガラス母材を形成する装置の一実施の形態の概略構成図、図２は図１に示した装置で形成した多孔質ガラス母材を透明ガラス化する工程の説明図、図３は図２に示した透明ガラス化する工程を経て形成されたガラス母材の縦断面図である。 Hereinafter, a preferred embodiment of a method for producing a glass base material according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an embodiment of an apparatus for forming a porous glass preform in the method for producing a glass preform according to the present invention, and FIG. 2 is a porous glass preform formed by the apparatus shown in FIG. FIG. 3 is a longitudinal sectional view of a glass base material formed through the transparent vitrification step shown in FIG. 2.

図１に示した装置１１は、いわゆるＶＡＤ法により、反応容器１２の内側の空間内で石英製のガラスロッドによるコア部分（クラッド部分の一部が含まれていても良い）２に対してガラス微粒子を堆積させて、コア部分２とその外周を包むクラッド部分３とを有した多孔質ガラス母材５を形成するものである。   The apparatus 11 shown in FIG. 1 uses a so-called VAD method to make glass against a core part (which may include a part of a cladding part) 2 made of a quartz glass rod in a space inside the reaction vessel 12. By depositing fine particles, a porous glass base material 5 having a core portion 2 and a clad portion 3 surrounding the outer periphery thereof is formed.

反応容器１２は、ガラス微粒子を生成して堆積させる際の高温の環境条件においても、塩素ガス等による腐食が極めて起こりにくい、二酸化ケイ素、炭化ケイ素、ニッケル、ニッケル合金等の材料を用いて形成されている。   The reaction vessel 12 is formed using a material such as silicon dioxide, silicon carbide, nickel, or a nickel alloy that is extremely unlikely to be corroded by chlorine gas or the like even under high temperature environmental conditions when generating and depositing glass particles. ing.

反応容器１２の中には、垂直方向に昇降可能な把持具１５が収容されている。この把持具１５は、長尺のコア部分２の上端を把持して、コア部分２を垂直方向に支持している。また、把持具１５は、その上方で回転引き上げ装置１６に接続されている。回転引き上げ装置１６は、把持具１５及び把持したコア部分２を、その軸回りに回転させることができる。   In the reaction vessel 12, a gripping tool 15 that can be moved up and down in the vertical direction is housed. The gripping tool 15 grips the upper end of the long core portion 2 and supports the core portion 2 in the vertical direction. Further, the gripping tool 15 is connected to the rotation pulling device 16 above the gripping tool 15. The rotary pulling device 16 can rotate the gripping tool 15 and the gripped core portion 2 about its axis.

反応容器１２の中には、ガラス微粒子生成用のバーナ２１が設けられている。このバーナ２１は、ガスを吹き出す複数のポートを有しており、そのポートからそれぞれ燃焼ガスとガラス原料ガスを吹き出し、燃焼ガスの燃焼により生じる酸水素火炎中において、ガラス原料を加水分解反応させて、ガラス微粒子を生成するものである。なお、燃焼ガスには、水素（Ｈ２）からなる燃焼性ガスと酸素（Ｏ２）からなる助燃性ガスが含まれ、ガラス原料ガスには四塩化ケイ素（ＳｉＣｌ４）が含まれる。また、バーナ２１は、生成したガラス微粒子をコア部分２に堆積させるように、コア部分２に向けて斜め上方に傾けて配置されている。なお、バーナ２１は複数用いても良い。 A burner 21 for generating glass fine particles is provided in the reaction vessel 12. The burner 21 has a plurality of ports for blowing out gas. The combustion gas and the glass raw material gas are blown out from the ports, respectively, and the glass raw material is hydrolyzed in an oxyhydrogen flame generated by the combustion of the combustion gas. The glass fine particles are generated. The combustion gas includes a combustible gas composed of hydrogen (H 2 ) and an auxiliary combustible gas composed of oxygen (O 2 ), and the glass raw material gas includes silicon tetrachloride (SiCl 4 ). Further, the burner 21 is disposed so as to be inclined obliquely upward toward the core portion 2 so that the generated glass fine particles are deposited on the core portion 2. A plurality of burners 21 may be used.

バーナ２１は、ガス供給装置２２からガスを導入するガス管２３に接続されており、このガス供給装置２２により、バーナ２１に供給されるガスの流量が適宜調整される。   The burner 21 is connected to a gas pipe 23 that introduces gas from the gas supply device 22, and the gas supply device 22 appropriately adjusts the flow rate of the gas supplied to the burner 21.

また、反応容器１２の内側には、非接触式の位置検出装置３１が設けられており、ガラス微粒子が堆積しつつあるクラッド部分３の位置を検出できるようになっている。位置検出装置３１としては、レーザ投受光装置やＣＣＤカメラを使用することができる。また、位置検出装置３１は、制御部３２と接続されており、クラッド部分３の位置データがこの制御部３２に送られる。   Further, a non-contact type position detecting device 31 is provided inside the reaction vessel 12 so that the position of the clad portion 3 where the glass fine particles are deposited can be detected. As the position detection device 31, a laser light projecting / receiving device or a CCD camera can be used. Further, the position detection device 31 is connected to the control unit 32, and the position data of the clad portion 3 is sent to the control unit 32.

また、制御部３２は、コア部分２の回転速度及び引き上げ速度を調節する回転引き上げ装置１６に接続されている。そして、この制御部３２は、コア部分２に堆積させるガラス微粒子を所定の堆積量にて堆積させるべく、位置検出装置３１からの位置データに基づいて回転引き上げ装置１６及びガス供給装置２２の動作を制御する。   Further, the control unit 32 is connected to a rotation pulling device 16 that adjusts the rotation speed and the pulling speed of the core portion 2. Then, the control unit 32 operates the rotary pulling device 16 and the gas supply device 22 based on the position data from the position detection device 31 so as to deposit the glass fine particles to be deposited on the core portion 2 with a predetermined deposition amount. Control.

上記構成の装置１１では、把持具１５によって反応容器１２内に垂直に吊り下げたコア部分２を軸回りに回転させながら、上方向に徐々に引き上げ、バーナ２１の火炎中に生成したガラス微粒子をコア部分２の外周に堆積させて、コア部分２とクラッド部分３とを有した多孔質ガラス母材５を形成する。   In the apparatus 11 having the above-described configuration, while rotating the core portion 2 vertically suspended in the reaction vessel 12 by the gripper 15 around the axis, the glass particles generated in the flame of the burner 21 are gradually pulled upward. A porous glass base material 5 having a core part 2 and a clad part 3 is formed by being deposited on the outer periphery of the core part 2.

ここで、本実施形態の装置１１では、制御部３２が回転引き上げ装置１６及び位置検出装置３１の検出結果に基づいて回転引き上げ装置１６を制御し、コア部分２の引き上げ速度を制御する。   Here, in the apparatus 11 of the present embodiment, the control unit 32 controls the rotary pulling device 16 based on the detection results of the rotary pulling device 16 and the position detecting device 31 to control the pulling speed of the core portion 2.

本実施の形態の装置１１で形成した多孔質ガラス母材５は、図２に示すように、有効部（製品として使う部分）Ｌｘの下端６から所定長さ分Ｌｍのクラッド部分３は、予め、下方に向かって徐々にガラス微粒子の堆積量を減少させて、下方に向かって徐々に外径が縮径する先細り形状に形成されている。   As shown in FIG. 2, the porous glass base material 5 formed by the apparatus 11 of the present embodiment has a cladding portion 3 of a predetermined length Lm from the lower end 6 of the effective portion (portion used as a product) Lx in advance. It is formed in a tapered shape in which the accumulation amount of the glass fine particles is gradually decreased downward and the outer diameter is gradually reduced downward.

本実施の形態の場合、コア部分２の外周にガラス微粒子を堆積させる工程において、前記先細り形状の部位では、有効部Ｌｘの他の部位に対してガラス微粒子を堆積させる際の嵩密度を下げるようにしている。堆積させたガラス微粒子の嵩密度を下げることにより、焼結する際の外径の収縮量が大きくなる。
クラッド部分３の有効部Ｌｘの下に連なる非有効部７は、前述の所定長さ分Ｌｍの先細り形状に滑らかに連なる先細り形状になっている。 In the case of the present embodiment, in the step of depositing glass fine particles on the outer periphery of the core portion 2, in the tapered portion, the bulk density when the glass fine particles are deposited on other portions of the effective portion Lx is lowered. I have to. By reducing the bulk density of the deposited glass particles, the amount of shrinkage of the outer diameter during sintering increases.
The non-effective portion 7 connected below the effective portion Lx of the clad portion 3 has a tapered shape that is smoothly connected to the tapered shape of the predetermined length Lm.

多孔質ガラス母材５の有効部Ｌｘの内、下端側の所定長さ分Ｌｍより上方の範囲では、回転引き上げ装置１６による引き上げ速度、バーナ２１によるクラッド部分３への原料の供給量の制御等によって、クラッド部分３の外径Ｄは一定値（基準値）になるように制御されて、コア部分２とクラッド部分３の外径比の軸方向での変動を抑えることが行われている。   Of the effective portion Lx of the porous glass base material 5, in the range above the predetermined length Lm on the lower end side, the pulling speed by the rotary pulling device 16, the control of the supply amount of the raw material to the cladding portion 3 by the burner 21, etc. Thus, the outer diameter D of the cladding portion 3 is controlled to be a constant value (reference value), and the variation in the axial direction of the outer diameter ratio between the core portion 2 and the cladding portion 3 is suppressed.

装置１１で形成した多孔質ガラス母材５は、図２に示すように、垂直に支持した状態のまま脱水焼結炉内のヒータ８により下端側から順に加熱して、脱水・焼結して透明ガラス化して、透明化されたガラス母材を得る。   As shown in FIG. 2, the porous glass preform 5 formed by the apparatus 11 is heated in order from the lower end side by the heater 8 in the dehydration sintering furnace while being vertically supported, and dehydrated and sintered. Transparent glass is obtained to obtain a transparent glass base material.

図３は、多孔質ガラス母材５の透明ガラス化によって得たガラス母材５Ａであり、図中の符号２Ａはコア部分、３Ａはクラッド部分であり、ＬｘＡは製品として利用される有効部である。   FIG. 3 shows a glass base material 5A obtained by converting the porous glass base material 5 into a transparent glass. Reference numeral 2A in the figure is a core portion, 3A is a cladding portion, and LxA is an effective portion used as a product. is there.

図２に示したように、透明ガラス化のために多孔質ガラス母材５が脱水・焼結される時には、多孔質ガラス母材５の上端が固定のため、多孔質ガラス母材５の下端側が上方へ収縮していくが、下端側ほど自重による負荷が小さくなるため、下端側では収縮に伴う外径の変化量が小さくなり、下端側の外径が相対的に大きくなる。
しかし、本実施の形態において透明ガラス化する多孔質ガラス母材５は、有効部Ｌｘの下端６から所定長さ分Ｌｍのクラッド部分３を、予め、下方に向かって徐々に外径が縮径する先細り形状に形成しているため、外径が増大しても、下端側における外径が許容範囲を超えて太くなることを防止できる。
即ち、本実施の形態におけるガラス母材の製造方法によれば、図３に示すように、透明ガラス化したガラス母材５Ａの有効部ＬｘＡにおける外径Ｄａの変動を抑えて、コア部分２Ａとクラッド部分３Ａの外径比の軸方向での変動の低減により、軸方向における屈折率分布の変動を極力低減することができる。 As shown in FIG. 2, when the porous glass base material 5 is dehydrated and sintered for transparent vitrification, the upper end of the porous glass base material 5 is fixed, so that the lower end of the porous glass base material 5 is fixed. Although the side contracts upward, the load due to its own weight decreases toward the lower end side, so that the amount of change in the outer diameter accompanying contraction decreases at the lower end side, and the outer diameter on the lower end side becomes relatively large.
However, the porous glass base material 5 to be transparent vitrified in the present embodiment has the outer diameter gradually reduced in advance from the lower end 6 of the effective portion Lx to the cladding portion 3 having a predetermined length Lm downward. Therefore, even if the outer diameter increases, it is possible to prevent the outer diameter on the lower end side from increasing beyond the allowable range.
That is, according to the manufacturing method of the glass base material in the present embodiment, as shown in FIG. 3, the variation in the outer diameter Da in the effective portion LxA of the glass base material 5A made into transparent glass is suppressed, and the core portion 2A and By reducing the fluctuation in the axial direction of the outer diameter ratio of the cladding portion 3A, the fluctuation in the refractive index distribution in the axial direction can be reduced as much as possible.

また、透明ガラス化したガラス母材の下端側が許容範囲を超えて太くなることを防止できるため、下端の外径の増大により次工程の炉に入らないなどの不具合が発生することがなく、下端を細くするために再度加熱して延伸するなどの余分な手間も不要になる。   In addition, since it is possible to prevent the lower end side of the glass base material that has become transparent glass from becoming thicker beyond the allowable range, problems such as not entering the furnace of the next process due to an increase in the outer diameter of the lower end do not occur. In order to reduce the thickness, there is no need for extra work such as heating and stretching again.

なお、脱水焼結炉の状態は、周囲の温度や湿度等の条件の影響により日々、微妙に変化するため、ガラス母材５Ａのクラッド部分３Ａの外径の変動を低減させるには、周囲の温度や湿度等の条件に応じて、前述のクラッド部分３の先細り形状の開始位置を修正することが必要になる。
その場合の修正方法としては、前ロットで製造されたガラス母材５Ａのクラッド部分３Ａの外径が許容値以上に大きいとき、次ロットではそれが解消されるように、多孔質ガラス母材５のクラッド部分３の先細り形状の開始位置が、前ロットの時の開始位置よりも上方に修正する方法が良い。
このように、前回のロットの製造結果を、次のロットの製造時にフィードバックすることで、先細り形状の開始位置を簡単に修正することができる。 In addition, since the state of the dehydration sintering furnace changes slightly daily due to the influence of conditions such as ambient temperature and humidity, in order to reduce fluctuations in the outer diameter of the cladding portion 3A of the glass base material 5A, In accordance with conditions such as temperature and humidity, it is necessary to correct the start position of the tapered shape of the cladding portion 3 described above.
In this case, as a correction method, when the outer diameter of the clad portion 3A of the glass base material 5A manufactured in the previous lot is larger than the allowable value, the porous glass base material 5 can be eliminated in the next lot. A method of correcting the taper-shaped start position of the clad portion 3 above the start position in the previous lot is preferable.
As described above, the start position of the tapered shape can be easily corrected by feeding back the manufacturing result of the previous lot when manufacturing the next lot.

なお、装置１１で多孔質ガラス母材５を形成する際、先細り形状にする所定長さ分Ｌｍは、有効部Ｌｘの１〜２５％の範囲で設定される。
また、前記所定長さ分Ｌｍにおいて、堆積させるガラス微粒子の嵩密度の低減により減少する堆積量は、基準の外径Ｄの部分における堆積量の１〜１０％に設定される。 In addition, when forming the porous glass preform | base_material 5 with the apparatus 11, predetermined length Lm made into a taper shape is set in the range of 1-25% of the effective part Lx.
In the predetermined length Lm, the deposition amount that is reduced by reducing the bulk density of the glass fine particles to be deposited is set to 1 to 10% of the deposition amount in the reference outer diameter D portion.

なお、装置１１において、多孔質ガラス母材５の有効部Ｌｘの下端の先細り形状は、次のようにしても形成することができる。
例えば、コア部分２の外周にガラス微粒子を堆積させる工程において、位置検出装置３１により規制するクラッド部分３の基準外径位置を、コア部分２の引き上げに応じて徐々に内側に移動させることにより、前記クラッド部分３の先細り形状が形成されるようにしても良い。 In addition, in the apparatus 11, the taper shape of the lower end of the effective part Lx of the porous glass base material 5 can also be formed as follows.
For example, in the step of depositing glass fine particles on the outer periphery of the core part 2, by gradually moving the reference outer diameter position of the clad part 3 regulated by the position detection device 31 in accordance with the pulling up of the core part 2, A tapered shape of the clad portion 3 may be formed.

また、コア部分２の外周にガラス微粒子を体積させる工程において、クラッド部分３としてガラス微粒子を吹き付けて堆積させるバーナ２１におけるガラス微粒子の原料流量を徐々に低減させることにより、クラッド部分３の先細り形状が形成されるようにしても良い。   Further, in the step of volumetric glass particles on the outer periphery of the core portion 2, by gradually reducing the raw material flow rate of the glass particles in the burner 21 where glass particles are sprayed and deposited as the cladding portion 3, the tapered shape of the cladding portion 3 is reduced. It may be formed.

更に、上記実施の形態では、装置１１による多孔質ガラス母材５の製造時に先細り形状を形成することとしたが、装置１１では有効部Ｌｘの全長に渡って外径が一定の多孔質ガラス母材を形成し、その後、機械的な研磨処理によりクラッド部分３の先細り形状を得るようにしても良い。   Further, in the above embodiment, the tapered shape is formed when the porous glass base material 5 is manufactured by the device 11, but in the device 11, the porous glass base having a constant outer diameter over the entire length of the effective portion Lx. A material may be formed, and then the tapered shape of the clad portion 3 may be obtained by mechanical polishing.

なお、本発明において、多孔質ガラス母材５を製造する方法は、上記実施の形態に示したＶＡＤ法に限るものではなく、ＯＶＤ法を採用することもできる。   In the present invention, the method for producing the porous glass base material 5 is not limited to the VAD method shown in the above embodiment, and the OVD method can also be adopted.

本発明に係るガラス母材の製造方法において、多孔質ガラス母材を形成する装置の一実施の形態の概略構成図である。In the manufacturing method of the glass base material which concerns on this invention, it is a schematic block diagram of one Embodiment of the apparatus which forms a porous glass base material. 図１に示した装置で形成した本発明に係る多孔質ガラス母材を透明ガラス化する工程の説明図である。It is explanatory drawing of the process of making the porous glass base material which concerns on this invention formed with the apparatus shown in FIG. 1 into transparent glass. 図２に示した透明ガラス化する工程を経て形成されたガラス母材の縦断面図である。It is a longitudinal cross-sectional view of the glass base material formed through the process of transparent vitrification shown in FIG. 図１に示した装置で形成した従来の多孔質ガラス母材を透明ガラス化する工程の説明図である。It is explanatory drawing of the process of transparentizing the conventional porous glass base material formed with the apparatus shown in FIG. 図４に示した形状の多孔質ガラス母材から形成されるガラス母材の縦断面図である。It is a longitudinal cross-sectional view of the glass base material formed from the porous glass base material of the shape shown in FIG.

符号の説明Explanation of symbols

２ コア部分
２Ａ コア部分
３ クラッド部分
３Ａ クラッド部分
５ 多孔質ガラス母材
５Ａ 多孔質ガラス母材
６ 下端
７ 非有効部
１１ 装置
１２ 反応容器
１５ 把持具
１６ 回転引き上げ装置
２１ バーナ
２２ ガス供給装置
２３ ガス管
３１ 位置検出装置
３２ 制御部
Ｄ 外径
Ｄａ 外径
Ｌｍ 所定長さ分
Ｌｘ 有効部
ＬｘＡ 有効部 2 Core part 2A Core part 3 Clad part 3A Clad part 5 Porous glass base material 5A Porous glass base material 6 Lower end 7 Ineffective part 11 Device 12 Reaction vessel 15 Holding tool 16 Rotating pulling device 21 Burner 22 Gas supply device 23 Gas Tube 31 Position detection device 32 Control part D Outer diameter Da Outer diameter Lm For a predetermined length Lx effective part LxA effective part

Claims (6)

バーナの火炎中に生成したガラス微粒子を、垂直に支持されたガラスロッドの外周あるいは下側に堆積させて、コア部分とその外周のクラッド部分とを有した多孔質ガラス母材を形成した後、前記多孔質ガラス母材を垂直に支持した状態のまま脱水・焼結して透明ガラス化して、透明化されたガラス母材を得るガラス母材の製造方法において、
前記多孔質ガラス母材の有効部の下端から前記有効部の長さに対し１％以上２５％以下の範囲内で設定された長さ分のクラッド部分は、予め、下方に向かって徐々にガラス微粒子の堆積量を前記有効部の他の部位に対して１％以上１０％以下の範囲内で減少させて、下方に向かって徐々に外径が小さく先細り形状に形成しておくことを特徴とするガラス母材の製造方法。 After the glass fine particles generated in the flame of the burner are deposited on the outer periphery or the lower side of the vertically supported glass rod, a porous glass base material having a core portion and a cladding portion on the outer periphery is formed. In the manufacturing method of the glass base material to obtain a transparent glass base material by dehydrating and sintering while maintaining the state in which the porous glass base material is supported vertically,
The clad portion of the length set in the range of 1% to 25% with respect to the length of the effective portion from the lower end of the effective portion of the porous glass base material is gradually lowered downward in advance. The accumulation amount of the fine particles is reduced within a range of 1% to 10% with respect to the other parts of the effective portion, and the outer diameter is gradually reduced toward the lower side, and the tapered shape is formed. A method for manufacturing a glass base material. 前ロットで製造されたガラス母材のクラッド部分の外径が許容値以上に大きいとき、次ロットではそれが解消されるように、前記クラッド部分の先細り形状の開始位置が、前ロットの時の開始位置よりも上方に修正されることを特徴とする請求項１に記載のガラス母材の製造方法。   When the outer diameter of the clad portion of the glass base material manufactured in the previous lot is larger than the allowable value, the start position of the tapered shape of the clad portion is the same as that in the previous lot so that it is eliminated in the next lot. The method for producing a glass base material according to claim 1, wherein the glass base material is corrected upward from the start position. 前記ガラスロッドの外周あるいは下側にガラス微粒子を堆積させる工程において、前記先細り形状の部位では、前記有効部の他の部位に対してガラス微粒子を堆積させる際の嵩密度を下げることを特徴とする請求項１又は２に記載のガラス母材の製造方法。   In the step of depositing the glass particles on the outer periphery or the lower side of the glass rod, the taper-shaped part lowers the bulk density when the glass particles are deposited on the other part of the effective part. The manufacturing method of the glass base material of Claim 1 or 2. 前記ガラスロッドの外周あるいは下側にガラス微粒子を堆積させる工程において、クラッド部分の基準外径位置を、ガラスロッドの引き上げに応じて徐々に内側に移動させることにより、前記クラッド部分の先細り形状を形成することを特徴とする請求項１又は２に記載のガラス母材の製造方法。   In the step of depositing glass particles on the outer periphery or lower side of the glass rod, the reference outer diameter position of the cladding portion is gradually moved inward according to the pulling up of the glass rod, thereby forming the tapered shape of the cladding portion. The manufacturing method of the glass base material of Claim 1 or 2 characterized by the above-mentioned. 前記ガラスロッドの外周あるいは下側にガラス微粒子を堆積させる工程において、クラッド部分としてガラス微粒子を吹き付けて堆積させるバーナにおける前記ガラス微粒子の原料流量を徐々に低減させることにより、前記クラッド部分の先細り形状が形成されることを特徴とする請求項１又は２に記載のガラス母材の製造方法。   In the step of depositing glass fine particles on the outer periphery or the lower side of the glass rod, by gradually reducing the raw material flow rate of the glass fine particles in a burner for spraying and depositing glass fine particles as a clad portion, the tapered shape of the clad portion is reduced. It forms, The manufacturing method of the glass base material of Claim 1 or 2 characterized by the above-mentioned. 前記多孔質ガラス母材のクラッド部分の先細り形状を、機械的な研磨処理により得ることを特徴とする請求項１又は２に記載のガラス母材の製造方法。   The method for producing a glass base material according to claim 1, wherein the tapered shape of the clad portion of the porous glass base material is obtained by a mechanical polishing process.
JP2007209861A 2007-08-10 2007-08-10 Manufacturing method of glass base material Active JP4420082B2 (en)

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JP2015096458A (en) * 2013-11-15 2015-05-21 住友電気工業株式会社 Manufacturing method for optical fiber and manufacturing method for glass preform for optical fiber

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015096458A (en) * 2013-11-15 2015-05-21 住友電気工業株式会社 Manufacturing method for optical fiber and manufacturing method for glass preform for optical fiber

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