JP2005075682A - Method of manufacturing porous glass preform - Google Patents

Method of manufacturing porous glass preform Download PDF

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JP2005075682A
JP2005075682A JP2003307810A JP2003307810A JP2005075682A JP 2005075682 A JP2005075682 A JP 2005075682A JP 2003307810 A JP2003307810 A JP 2003307810A JP 2003307810 A JP2003307810 A JP 2003307810A JP 2005075682 A JP2005075682 A JP 2005075682A
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glass
burner
flow rate
surface temperature
base material
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Shinji Nakahara
慎二 中原
Mitsuru Takagi
充 高城
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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
    • C03B37/0142—Reactant deposition burners
    • 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
    • C03B2207/00—Glass deposition burners
    • C03B2207/36—Fuel or oxidant details, e.g. flow rate, flow rate ratio, fuel additives
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/70—Control measures

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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General 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)
  • Glass Melting And Manufacturing (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a porous glass preform by which the porous glass preform having an outside diameter uniform in the longitudinal direction and small in variation. <P>SOLUTION: The method of manufacturing the porous glass preform is carried out by forming glass particles by a burner 7 for synthesizing the glass particles, pulling up a glass rod 11 while axially rotating and depositing the glass particles on the glass rod 11. The flow rate of a gas for burning or a gas for a glass raw material which is supplied to the burner 7 is controlled based on the measured value of the growing speed or the surface temperature of a glass particle deposited body 19 deposited on the glass rod 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明はガラス微粒子を堆積させて作製する多孔質ガラス母材の製造方法に関する。   The present invention relates to a method for producing a porous glass base material produced by depositing glass fine particles.

高速・大容量通信として利用される光ファイバは、主にコアとクラッドから構成されており、ガラス微粒子の堆積体である多孔質ガラス母材を脱水・焼結してガラス母材に加工後、このガラス母材を線引きすることにより製造される。光ファイバの製造のもととなる多孔質ガラス母材を製造する方法としては、VAD（Vapour-phase axial deposition method）法がよく知られている。このVAD法は、バーナの火炎中にガラス微粒子を生成させ、生成したガラス微粒子をガラス棒の周りに堆積させて、円柱状の多孔質ガラス母材を形成していく方法である。   An optical fiber used for high-speed and large-capacity communication is mainly composed of a core and a clad, and after dewatering and sintering the porous glass base material, which is a deposit of glass particles, into a glass base material, It is manufactured by drawing this glass base material. A VAD (Vapour-phase axial deposition method) method is well known as a method for producing a porous glass base material that is the basis for producing an optical fiber. This VAD method is a method in which glass fine particles are generated in a flame of a burner, and the generated glass fine particles are deposited around a glass rod to form a cylindrical porous glass base material.

図３に、ＶＡＤ法による多孔質ガラス母材の製造方法の従来例を示す。図３において、出発ロッド101は、回転するチャック102に把持されたメインシード棒103に取り付けられ、回転させられる。この出発ロッド101の外周には、ガラス微粒子合成用バーナー105により生成されたガラス微粒子が堆積され、ガラス微粒子堆積体106が合成される。この堆積面107の下方に出発ロッドの外径測定器108が設置されており、出発ロッド101の外径のデータが得られる。また、チャック102はガラス微粒子堆積体106の合成に伴って上昇させられるが、このときの上昇速度は速度変換器109によりモニターされる（特許文献１参照。）。
特開平５−４８２５号公報 FIG. 3 shows a conventional example of a method for producing a porous glass base material by the VAD method. In FIG. 3, the starting rod 101 is attached to the main seed bar 103 held by the rotating chuck 102 and rotated. On the outer periphery of the starting rod 101, glass fine particles generated by the glass fine particle synthesizing burner 105 are deposited, and a glass fine particle deposit 106 is synthesized. A starting rod outer diameter measuring device 108 is installed below the deposition surface 107, and data of the outer diameter of the starting rod 101 is obtained. Further, the chuck 102 is raised along with the synthesis of the glass particulate deposit 106, and the rising speed at this time is monitored by the speed converter 109 (see Patent Document 1).
JP-A-5-4825

従来のＶＡＤ法を用いた多孔質ガラス母材の製造方法では、ガラス微粒子の付着により形成されたガラス微粒子堆積体のある位置での成長速度（ガラス微粒子の付着速度）を監視して、このデータを基に、ガラス微粒子堆積体の引き上げ速度を制御することが行われている。
このガラス微粒子堆積体の引き上げ速度の制御は、製造される多孔質ガラス母材の外径変動に大きな影響を及ぼすことがあり、この速度は一定であるか、あるいは、極めて限られた範囲内の変動であることが望ましい。 In the conventional method for producing a porous glass base material using the VAD method, this data is obtained by monitoring the growth rate (glass particle adhesion rate) at a certain position of the glass particle deposit formed by the adhesion of glass particles. Based on the above, the pulling speed of the glass particulate deposit is controlled.
Control of the pulling-up speed of the glass particulate deposit can have a large effect on fluctuations in the outer diameter of the porous glass base material to be produced, and this speed is constant or within a very limited range. It is desirable to be variable.

しかしながら、多孔質ガラス母材の製造では、反応容器内の雰囲気（温度、湿度、気圧等）、バーナへ供給する燃焼用ガスやガラス原料用ガスの流量等のガラス微粒子堆積体の製造環境に変動が生じることがあり、これにより製造過程にあるガラス微粒子の付着具合や成長速度に変動が生じてしまう。このガラス微粒子の付着具合や成長速度に応じ、ガラス微粒子堆積体の引き上げ速度を大きく制御することがあり、その結果、従来の多孔質ガラス母材の製造方法では、ガラス微粒子堆積体の外径が均一になりにくかった。
このようにガラス微粒子堆積体の成長速度等のデータに基づいて、ガラス微粒子堆積体の引き上げ速度を直接変化させるのみでは、外径変動を高精度に制御することが難しかった。
一方、ガラス微粒子堆積体の表面温度についても、製造環境の変動の影響を受けるため、表面温度を所望範囲内で制御することが難しく、その結果、得られる多孔質ガラス母材の外径が均一でなくなることがあった。 However, in the production of the porous glass base material, the atmosphere in the reaction vessel (temperature, humidity, atmospheric pressure, etc.), the flow rate of the combustion gas supplied to the burner and the flow rate of the glass raw material gas, etc. vary in the production environment of the glass particulate deposit This may cause fluctuations in the degree of adhesion and growth rate of the glass fine particles in the manufacturing process. Depending on the degree of adhesion and growth rate of the glass fine particles, the pulling rate of the glass fine particle deposit may be largely controlled. As a result, in the conventional method for producing a porous glass base material, the outer diameter of the glass fine particle deposit is small. It was difficult to be uniform.
As described above, it is difficult to control the fluctuation of the outer diameter with high accuracy only by directly changing the pulling rate of the glass fine particle deposit based on the data such as the growth rate of the glass fine particle deposit.
On the other hand, since the surface temperature of the glass particulate deposit is also affected by fluctuations in the manufacturing environment, it is difficult to control the surface temperature within a desired range, and as a result, the outer diameter of the resulting porous glass base material is uniform. Sometimes disappeared.

本発明の目的は、外径が長手方向に均一であり、ばらつきの少ない多孔質ガラス母材を製造できる多孔質ガラス母材の製造方法を提供することである。   The objective of this invention is providing the manufacturing method of the porous glass base material which can manufacture the porous glass base material with an outer diameter uniform in a longitudinal direction, and few dispersion | variations.

上記目的を達成するために、本発明に係る多孔質ガラス母材の製造方法は、燃焼用ガスとガラス原料用ガスとをバーナに供給してガラス微粒子を生成させ、ガラス棒を軸回転させながら引き上げ、前記ガラス微粒子を前記ガラス棒の外周に堆積させて多孔質ガラス母材を形成する多孔質ガラス母材の製造方法であって、
前記ガラス棒に堆積したガラス微粒子堆積体成長部の成長速度の計測値又は表面温度の計測値に基づいて、前記バーナに供給する燃焼用ガス及びガラス原料用ガスの少なくともいずれかの流量を制御することを特徴としている。 In order to achieve the above object, the method for producing a porous glass preform according to the present invention supplies a combustion gas and a glass raw material gas to a burner to generate glass fine particles, while rotating the glass rod axially. A method for producing a porous glass base material by pulling up and depositing the glass fine particles on the outer periphery of the glass rod to form a porous glass base material,
The flow rate of at least one of the combustion gas and the glass raw material gas supplied to the burner is controlled based on the measured value of the growth rate of the glass particulate deposit growing part deposited on the glass rod or the measured value of the surface temperature. It is characterized by that.

上記製造方法において、前記ガラス微粒子堆積体成長部の成長速度の計測値に基づいて、前記ガラス棒の引き上げ速度を制御することが好ましい。   In the manufacturing method described above, it is preferable to control the pulling rate of the glass rod based on the measured value of the growth rate of the glass fine particle deposit growing part.

このように、バーナへ供給するガス流量を増減させると、ガラス微粒子堆積体の堆積効率や成長速度を変化させることができ、多孔質ガラス母材の外径を高精度に制御できる。よって、前記したような要因により、ガラス微粒子堆積体成長部の成長速度又は表面温度に変動が生じた時にも、上記のようにバーナへのガス流量を制御すれば、ゆるやかに成長速度と表面温度を修正することができる。従って、本発明の製造方法によれば、外径が長手方向に均一で、ばらつきの少ない多孔質ガラス母材を製造することができる。   As described above, when the flow rate of the gas supplied to the burner is increased or decreased, the deposition efficiency and growth rate of the glass particulate deposit can be changed, and the outer diameter of the porous glass base material can be controlled with high accuracy. Therefore, even when the growth rate or surface temperature of the glass particulate deposit growth part varies due to the factors as described above, if the gas flow rate to the burner is controlled as described above, the growth rate and the surface temperature are gradually reduced. Can be corrected. Therefore, according to the manufacturing method of the present invention, it is possible to manufacture a porous glass base material having a uniform outer diameter in the longitudinal direction and little variation.

また、前記燃焼用ガス又はガラス原料用ガスの流量制御において、水素ガスの流量を制御することが好ましい。   In the flow rate control of the combustion gas or the glass raw material gas, it is preferable to control the flow rate of hydrogen gas.

また、上記多孔質ガラス母材の製造方法においては、予め前記ガラス微粒子堆積体の成長速度の目標値を設定し、前記ガラス微粒子堆積体成長部の成長速度の計測値が前記目標値より大きいときに、前記バーナへ供給する水素ガスの流量を増加させ、前記ガラス微粒子堆積体成長部の成長速度の計測値が前記目標値より小さいときに、前記バーナへ供給する水素ガスの流量を減少させることが好ましい。   In the method for producing a porous glass base material, when a target value of the growth rate of the glass particulate deposit is set in advance, and a measured value of the growth rate of the glass particulate deposit growth part is larger than the target value In addition, the flow rate of hydrogen gas supplied to the burner is increased when the flow rate of the hydrogen gas supplied to the burner is increased and the measured value of the growth rate of the glass particulate deposit growth part is smaller than the target value. Is preferred.

また、予め前記ガラス微粒子堆積体の表面温度の目標値を測定し、前記ガラス微粒子堆積体成長部の表面温度の計測値が前記目標値より大きいときに、前記バーナへ供給する水素ガスの流量を減少させ、前記ガラス微粒子堆積体成長部の表面温度の計測値が前記目標値より小さいときに、前記バーナへ供給する水素ガスの流量を増加させることが好ましい。   Further, a target value of the surface temperature of the glass particulate deposit is measured in advance, and when the measured value of the surface temperature of the glass particulate deposit growth portion is larger than the target value, the flow rate of hydrogen gas supplied to the burner is set. It is preferable that the flow rate of the hydrogen gas supplied to the burner is increased when the measured value of the surface temperature of the glass fine particle deposit growing part is smaller than the target value.

本発明の多孔質ガラス母材の製造方法によれば、ガラス微粒子堆積体の成長速度又は表面温度の計測値に基づいて、バーナへ供給する燃焼用ガス及びガラス原料用ガスの少なくともいずれかの流量を制御することにより、外径が長手方向に高精度に均一化され、ばらつきの少ない多孔質ガラス母材を製造できる。   According to the method for producing a porous glass base material of the present invention, the flow rate of at least one of the combustion gas and the glass raw material gas supplied to the burner based on the measured value of the growth rate or surface temperature of the glass particulate deposit. By controlling the above, it is possible to manufacture a porous glass base material having a uniform outer diameter with high accuracy in the longitudinal direction and less variation.

以下、本発明に係る多孔質ガラス母材の製造方法の実施の形態を図面を参照して説明する。
図１は、本実施形態に係る多孔質ガラス母材の製造装置を示しており、（ａ）は概略正面図、（ｂ）は底面から見た図を示している。図１に示すように、この多孔質ガラス母材の製造装置１０は反応容器１を有しており、この反応容器１の上部には、拡縮自在の開口部５ａを有する開閉板５が設けられている。反応容器１の外側上方には吊り下げ装置１３が設置されており、シード棒１２が吊り下げ装置１３によって吊り下げられている。吊り下げられたシード棒１２には、ガラス棒１１が取り付けられており、ガラス棒１１は開口部５ａを通って、反応容器１の内部へ導入されている。
吊り下げ装置１３は、シード棒１２に取り付けられたガラス棒１１を、軸回転可能かつ軸方向の移動可能にしている。また、吊り下げ装置１３は、ガラス棒１１の軸方向の移動速度の変動が可能なように構成されている。
このガラス棒１１の外周にガラス微粒子を堆積させていくと、中心にガラス棒１１を有するガラス微粒子堆積体１９を作製することができる。 Embodiments of a method for producing a porous glass base material according to the present invention will be described below with reference to the drawings.
FIG. 1 shows an apparatus for producing a porous glass base material according to the present embodiment, wherein (a) is a schematic front view, and (b) is a view seen from the bottom. As shown in FIG. 1, the porous glass preform manufacturing apparatus 10 has a reaction vessel 1, and an opening / closing plate 5 having an expandable / contractible opening 5 a is provided on the upper portion of the reaction vessel 1. ing. A suspending device 13 is installed on the outer upper side of the reaction vessel 1, and the seed bar 12 is suspended by the suspending device 13. A glass rod 11 is attached to the suspended seed rod 12, and the glass rod 11 is introduced into the reaction vessel 1 through the opening 5a.
The suspending device 13 makes the glass rod 11 attached to the seed rod 12 axially rotatable and axially movable. Moreover, the suspending device 13 is configured so that the movement speed of the glass rod 11 in the axial direction can be changed.
When glass particles are deposited on the outer periphery of the glass rod 11, a glass particle deposit 19 having the glass rod 11 at the center can be produced.

反応容器１の下部には、ガラス微粒子を生成するバーナ７と、反応容器１内の未堆積ガラス微粒子等を排出する排気口９とが設けられている。
バーナ７は、ガスの吹き出し口が複数のポートを有するマルチポート（多重管）構造となっており、各ポートから燃焼用ガス及びガラス原料用ガスを吹き出し、燃焼用ガスにより生じる火炎中において、ガラス原料を酸化反応又は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。ここで、バーナ７へ供給する燃焼用ガスとは、主に支燃性ガス及び助燃性ガスとからなり、支燃性ガスとしては水素、助燃性ガスとしては酸素が一例として挙げられる。また、ガラス原料用ガスとしては、四塩化珪素（ＳｉＣｌ４）が一例として挙げられる。 Below the reaction vessel 1, a burner 7 that generates glass particles and an exhaust port 9 that discharges undeposited glass particles in the reaction vessel 1 are provided.
The burner 7 has a multi-port structure in which the gas outlet has a plurality of ports. The gas for combustion and the glass raw material gas are blown out from each port, and the glass in the flame generated by the combustion gas The raw material is oxidized or hydrolyzed to produce glass fine particles. Here, the combustion gas supplied to the burner 7 mainly includes a combustion-supporting gas and a supplementary combustion gas, and examples of the combustion-supporting gas include hydrogen and examples of the combustion-supporting gas include oxygen. An example of the glass raw material gas is silicon tetrachloride (SiCl 4 ).

バーナ７には、これらの燃焼用ガス及びガラス原料用ガスを供給するための酸素供給タンク１５、水素供給タンク１６、及びガラス原料供給タンク１７が接続されており、燃焼用ガスやガラス用原料ガスをバーナ７の各ポートへ別々に供給できるようになっている。各タンクのバルブ１５ａ、１６ａ及び１７ａには、ライン２４を介してガス流量制御装置６が接続されており、ガス流量制御装置６は、ライン２３を介して制御装置４へ接続されている。このガス流量制御装置６により、各タンクからバーナへ供給されるガス流量が制御される。   The burner 7 is connected to an oxygen supply tank 15, a hydrogen supply tank 16, and a glass raw material supply tank 17 for supplying these combustion gas and glass raw material gas. Can be separately supplied to each port of the burner 7. A gas flow rate control device 6 is connected to the valves 15 a, 16 a and 17 a of each tank via a line 24, and the gas flow rate control device 6 is connected to the control device 4 via a line 23. The gas flow rate control device 6 controls the gas flow rate supplied from each tank to the burner.

また、反応容器１の外部には、バーナ７により形成されたガラス微粒子堆積体１９の底面部に向けて、投光器２が設けられており、投光器２からの光ビーム１８を受光できる位置に、受光器３が配置されている（図１（ｂ）参照。）。この投光器２及び受光器３により、ガラス微粒子堆積体１９の成長部の成長速度を測定できる。受光器３は、ライン２１を介して制御装置４へ接続されている。また、制御装置４はライン２５を介して吊り下げ装置１３へと接続されている。   In addition, a projector 2 is provided outside the reaction vessel 1 toward the bottom surface of the glass particulate deposit 19 formed by the burner 7, and receives light at a position where the light beam 18 from the projector 2 can be received. A container 3 is arranged (see FIG. 1B). With the light projector 2 and the light receiver 3, the growth rate of the growth part of the glass fine particle deposit 19 can be measured. The light receiver 3 is connected to the control device 4 via a line 21. The control device 4 is connected to the suspension device 13 via a line 25.

さらに、反応容器１のバーナ７の近傍には、温度測定器８が備えられている。温度測定器８は、ガラス微粒子堆積体１９の底面部において、バーナ７により加熱される領域に向けて配置されており、この加熱領域内点Ｔの表面温度を測定することができる。なお、温度測定器８としては、ここでは放射温度計を用いることができるが、この他にサーモグラフィ等の底面部全体の表面温度を計測する装置を用いてもよい。
温度測定器８は、ライン２２を介して制御装置４に接続されており、温度測定器８により測定された点Ｔの表面温度の計測値は制御装置４へと送られる。 Further, a temperature measuring device 8 is provided in the vicinity of the burner 7 of the reaction vessel 1. The temperature measuring device 8 is arranged toward the region heated by the burner 7 on the bottom surface portion of the glass fine particle deposit 19, and can measure the surface temperature of the heating region inner point T. As the temperature measuring device 8, a radiation thermometer can be used here, but in addition to this, a device for measuring the surface temperature of the entire bottom portion such as thermography may be used.
The temperature measuring device 8 is connected to the control device 4 via a line 22, and the measured value of the surface temperature at the point T measured by the temperature measuring device 8 is sent to the control device 4.

この製造装置１０を用いて多孔質ガラス母材を製造する方法を以下に説明する。まず、シード棒１２の先端にガラス棒１１を取り付け、このシード棒１２を吊り下げ装置１３に吊り下げる。そして、吊り下げ装置１３を作動させ、ガラス棒１１のガラス微粒子堆積開始点とバーナ７の吹き出し口との距離が所望距離となるように、ガラス棒１１を降下させる。
一方、酸素供給タンク１５、水素供給タンク１６及びガラス原料供給タンク１７の各バルブ１５ａ、１６ａ及び１７ａを開放してバーナ７への供給を開始する。必要に応じて供給タンクを増設して、窒素、アルゴン、ヘリウム等の不活性ガスや、四塩化ゲルマニウム（ＧｅＣｌ4）、ＰＯＣｌ3等の屈折率制御用原料ガス等をバーナ７へ供給してもよい。 A method for manufacturing a porous glass base material using the manufacturing apparatus 10 will be described below. First, the glass rod 11 is attached to the tip of the seed rod 12, and the seed rod 12 is suspended from the suspension device 13. Then, the suspension device 13 is operated, and the glass rod 11 is lowered so that the distance between the glass fine particle deposition start point of the glass rod 11 and the outlet of the burner 7 becomes a desired distance.
On the other hand, the valves 15a, 16a and 17a of the oxygen supply tank 15, the hydrogen supply tank 16 and the glass raw material supply tank 17 are opened, and the supply to the burner 7 is started. If necessary, an additional supply tank may be added to supply an inert gas such as nitrogen, argon or helium, or a refractive index control source gas such as germanium tetrachloride (GeCl 4 ) or POCl 3 to the burner 7. Good.

ガラス棒１１を軸回転させ、ガラス棒１１に向かってバーナ７から酸水素火炎を放射する。この酸水素火炎中では、ガラス原料用ガスの酸化反応又は加水分解反応によりガラス微粒子が生成する。この生成したガラス微粒子をガラス棒１１の外周に付着させながら、ガラス棒１１を所定速度で引き上げて、徐々にガラス微粒子堆積体１９を形成し、成長させていく。   The glass rod 11 is rotated about its axis, and an oxyhydrogen flame is emitted from the burner 7 toward the glass rod 11. In this oxyhydrogen flame, glass fine particles are generated by an oxidation reaction or hydrolysis reaction of the glass raw material gas. While the generated glass particles are adhered to the outer periphery of the glass rod 11, the glass rod 11 is pulled up at a predetermined speed to gradually form and grow the glass particle deposit 19.

ガラス微粒子堆積体１９を形成・成長させる際には、投光器２及び受光器３により、常にガラス微粒子堆積体１９成長部（底面部）の位置を検出して、ガラス微粒子堆積体１９成長部の成長速度を計測し、この成長速度に基づいて吊り下げ装置１３の引き上げ速度を制御する。
具体的には、投光器２からレーザ光１８を発して、レーザ光１８がガラス微粒子堆積体１９の底面部上の点Ｐに接するようにし、受光器３によりこのレーザ光１８の光量を測定する。点Ｐは、ガラス微粒子堆積体１９の底面部上の任意の位置に設定される。なお、投光器２及び受光器３の代わりに、ＣＣＤカメラ等を用いてガラス微粒子堆積体１９の底面部を撮影し、画像解析することによりガラス微粒子堆積体１９の点Ｐの位置を検出することもできる。 When forming and growing the glass particulate deposit 19, the position of the glass particulate deposit 19 growth portion (bottom portion) is always detected by the projector 2 and the light receiver 3 to grow the glass particulate deposit 19 growth portion. The speed is measured, and the lifting speed of the suspending device 13 is controlled based on this growth speed.
Specifically, a laser beam 18 is emitted from the projector 2 so that the laser beam 18 is in contact with a point P on the bottom surface of the glass fine particle deposit 19, and the light amount of the laser beam 18 is measured by the light receiver 3. The point P is set at an arbitrary position on the bottom surface of the glass fine particle deposit 19. Note that, instead of the projector 2 and the light receiver 3, the position of the point P of the glass fine particle deposit 19 may be detected by photographing the bottom surface of the glass fine particle deposit 19 using a CCD camera or the like and analyzing the image. it can.

受光器３により測定された受光量のデータは、所定の時間毎に制御装置４へと送られる。制御装置４は、この受光量のデータから点Ｐでの成長速度を算出し、この成長速度のデータに基づいて、吊り下げ装置１３に対してガラス棒１１の引き上げ速度の制御を行う。これにより、ガラス微粒子堆積体１９の最下端とバーナとの距離が常に一定に保たれることになる。   The received light amount data measured by the light receiver 3 is sent to the control device 4 every predetermined time. The control device 4 calculates the growth rate at the point P from the received light amount data, and controls the lifting speed of the glass rod 11 for the suspension device 13 based on the growth rate data. As a result, the distance between the lowermost end of the glass particulate deposit 19 and the burner is always kept constant.

また、これとは別に、ガラス微粒子堆積体１９成長部（底面部）における点Ｔの表面温度を温度測定器８により測定する。ここで、点Ｔは、ガラス微粒子堆積体１９の底面部上の任意の位置に設定される。温度測定器８により計測された点Ｔの温度の計測値は、制御装置４へと送られる。   Separately from this, the temperature measuring device 8 measures the surface temperature of the point T in the growth part (bottom part) of the glass fine particle deposit 19. Here, the point T is set at an arbitrary position on the bottom surface of the glass fine particle deposit 19. The measured value of the temperature at the point T measured by the temperature measuring device 8 is sent to the control device 4.

制御装置４は、上記のようにして計測されたガラス微粒子堆積体１９成長部の成長速度又は表面温度の計測値に基づいて、ガス流量制御装置６に信号を送り、酸素供給タンク１５、水素供給タンク１６及びガラス原料供給タンク１７の各バルブ１５ａ、１６ａ及び１７ａの開閉を制御して、バーナ７へ供給する燃焼用ガス及びガラス原料用ガスの少なくともいずれかの流量を制御する。
前記したように、ガラス微粒子堆積体１９の形成においては、反応容器内の雰囲気（温度、湿度、気圧等）、燃焼用ガスやガラス原料用ガスの流量等に変動がおこり、これによりガラス微粒子堆積体１９成長部の成長速度又は表面温度が変動する場合がある。本実施形態に係る製造方法においては、この成長速度又は表面温度の変動に対して、ガラス棒１１の引き上げ速度を制御するとともに、バーナ７へ供給する燃焼用ガス又はガラス原料用ガスの流量を制御する。このガス流量の制御は、ガラス棒１１に堆積するガラス微粒子の成長速度又は表面温度が所望の速度又は温度となるように制御する。 The control device 4 sends a signal to the gas flow rate control device 6 based on the measured value of the growth rate or surface temperature of the glass fine particle deposit 19 growing portion measured as described above, and supplies the oxygen supply tank 15 and the hydrogen supply. By controlling the opening and closing of the valves 15a, 16a and 17a of the tank 16 and the glass raw material supply tank 17, the flow rate of at least one of the combustion gas and the glass raw material gas supplied to the burner 7 is controlled.
As described above, in the formation of the glass particulate deposit 19, the atmosphere in the reaction vessel (temperature, humidity, pressure, etc.), the flow rate of the combustion gas and the glass raw material gas, etc. vary, and this causes the glass particulate deposition. The growth rate or surface temperature of the body 19 growth part may vary. In the manufacturing method according to the present embodiment, the pulling speed of the glass rod 11 is controlled with respect to the fluctuation of the growth rate or the surface temperature, and the flow rate of the combustion gas or the glass raw material gas supplied to the burner 7 is controlled. To do. The gas flow rate is controlled so that the growth rate or surface temperature of the glass particles deposited on the glass rod 11 becomes a desired rate or temperature.

従来、コアロッドを中心に有するタイプの多孔質ガラス母材をＶＡＤ法により製造する方法においては、母材の外径を均一にする手段として、ガラス微粒子堆積体１９の成長速度に対して、ガラス棒１１の引き上げ速度を増減させることが行われていた。しかしながら、このように多孔質ガラス母材を製造すると、ガラス微粒子体積体１９の堆積面とバーナ７との距離は一定に保たれるが、ガラス微粒子堆積体１９の成長速度や表面温度が変動したときに、これらを所定の値になるように制御することは困難であった。
本実施形態では、バーナ７へのガス流量を制御すると、バーナ７から放出される火炎の大きさや火炎の温度、火炎中のガラス微粒子の含有量等を調整でき、その時バーナ７により形成されているガラス微粒子の堆積層の厚みのみをコントロールできるので、ガラス微粒子堆積体１９の成長速度又は表面温度の変動をゆるやかに修正できる。よって、引き上げ速度の変動幅を小さくして、成長速度又は表面温度の大きな変動を防止できるので、外径が長手方向に高精度に均一化された多孔質ガラス母材を得ることができる。 Conventionally, in a method of manufacturing a porous glass base material of a type having a core rod as the center by the VAD method, as a means for making the outer diameter of the base material uniform, a glass rod is used with respect to the growth rate of the glass particulate deposit 19. The lifting speed of 11 was increased or decreased. However, when the porous glass base material is manufactured in this way, the distance between the deposition surface of the glass fine particle volume 19 and the burner 7 is kept constant, but the growth rate and surface temperature of the glass fine particle deposition body 19 fluctuated. At times, it has been difficult to control these to be a predetermined value.
In this embodiment, when the gas flow rate to the burner 7 is controlled, the size of the flame released from the burner 7, the temperature of the flame, the content of glass fine particles in the flame, and the like can be adjusted. Since only the thickness of the glass fine particle deposition layer can be controlled, the fluctuation of the growth rate or surface temperature of the glass fine particle deposit 19 can be gently corrected. Therefore, since the fluctuation range of the pulling rate can be reduced to prevent a large fluctuation in the growth rate or the surface temperature, it is possible to obtain a porous glass base material whose outer diameter is made highly uniform in the longitudinal direction.

また、より詳しくは、ガラス微粒子堆積体１９を形成する時の成長速度又は表面温度の目標値を予め設定しておき、この目標値に対して、計測した成長速度又は表面温度の値が近づくように、燃焼用ガス又はガラス原料用ガスのガス流量を増減させるとよい。   More specifically, a target value of the growth rate or surface temperature when the glass fine particle deposit 19 is formed is set in advance, and the measured growth rate or surface temperature value approaches this target value. Further, the gas flow rate of the combustion gas or the glass raw material gas may be increased or decreased.

ここで、上記燃焼用ガス又は原料用ガスの流量制御においては、水素ガス、酸素ガス、ガラス原料用ガスのいずれのガス流量を制御してもよいが、中でも、バーナ７の火炎温度を調整しやすいことから、水素ガスの流量を制御することが好ましい。   Here, in the flow rate control of the combustion gas or the raw material gas, any gas flow rate of hydrogen gas, oxygen gas, or glass raw material gas may be controlled, and among them, the flame temperature of the burner 7 is adjusted. Since it is easy, it is preferable to control the flow rate of hydrogen gas.

例えば、ガラス微粒子堆積体１９の成長速度の計測値に基づいて、水素ガス流量を変更する場合、予めガラス微粒子堆積体１９の成長速度の目標値を設定し、ガラス微粒子堆積体１９成長部の成長速度の計測値が目標値より大きいときに、バーナ７への水素ガスの流量を増加させ、ガラス微粒子堆積体１９成長部の成長速度の計測値が目標値より小さいときに、バーナ７への水素ガスの流量を減少させることが好ましい。   For example, when changing the hydrogen gas flow rate based on the measured value of the growth rate of the glass particulate deposit 19, the target value of the growth rate of the glass particulate deposit 19 is set in advance, and the growth of the growth portion of the glass particulate deposit 19 is performed. When the measured value of the velocity is larger than the target value, the flow rate of hydrogen gas to the burner 7 is increased, and when the measured value of the growth rate of the glass particulate deposit 19 growth portion is smaller than the target value, the hydrogen to the burner 7 is increased. It is preferable to reduce the gas flow rate.

ガラス微粒子堆積体１９の成長速度が大きいときは、受光器３の検出信号により、ガラス微粒子堆積体１９の引き上げ速度の増加が指示される。この引き上げ速度の増大が連続すると、ガラス微粒子堆積体１９とバーナ７との距離が所望距離より離れて、ガラス微粒子堆積体１９の外径が小さくなる傾向がある。この場合、水素ガス供給タンク１６のバルブ１６ａを制御して、水素ガス流量を増加させる。これにより、ガラス微粒子の堆積量を増加させ、かつガラス微粒子が堆積しているガラス微粒子堆積体１９の底面部の温度を高くして、ガラス微粒子堆積体１９の外径を増大させる方向とする。
逆に、ガラス微粒子堆積体１９の成長速度が小さいときには、引き上げ速度が小さく、外径が大きくなる傾向にある。この場合、水素ガス供給タンク１６のバルブ１６ａを制御して、水素ガス流量を減少させる。これにより、堆積量を減少させ、かつ堆積面の温度を低下させて、ガラス微粒子堆積体１９の外径を減少させる方向とする。 When the growth rate of the glass particulate deposit 19 is high, an increase in the pulling rate of the glass particulate deposit 19 is instructed by the detection signal of the light receiver 3. When the increase in the pulling rate continues, the distance between the glass particulate deposit 19 and the burner 7 tends to be larger than the desired distance, and the outer diameter of the glass particulate deposit 19 tends to decrease. In this case, the valve 16a of the hydrogen gas supply tank 16 is controlled to increase the hydrogen gas flow rate. As a result, the amount of glass fine particles deposited is increased, and the temperature of the bottom surface of the glass fine particle deposit 19 on which the glass fine particles are deposited is increased to increase the outer diameter of the glass fine particle deposit 19.
Conversely, when the growth rate of the glass particulate deposit 19 is low, the pulling rate is low and the outer diameter tends to be large. In this case, the valve 16a of the hydrogen gas supply tank 16 is controlled to decrease the hydrogen gas flow rate. As a result, the amount of deposition is reduced, and the temperature of the deposition surface is lowered to reduce the outer diameter of the glass particulate deposit 19.

また、ガラス微粒子堆積体１９の表面温度の計測値に基づいて、水素ガス流量を変更する場合にも、予めガラス微粒子堆積体１９の表面温度の目標値を設定しておくことが望ましい。ガラス微粒子堆積体１９成長部の表面温度の計測値が目標値より大きいときに、バーナ７への水素ガスの流量を減少させ、ガラス微粒子堆積体１９成長部の表面温度の計測値が目標値より小さいときに、バーナ７への水素ガスの流量を増加させることが好ましい。   In addition, when changing the hydrogen gas flow rate based on the measured value of the surface temperature of the glass particulate deposit 19, it is desirable to set a target value for the surface temperature of the glass particulate deposit 19 in advance. When the measured value of the surface temperature of the growth part of the glass particulate deposit 19 is larger than the target value, the flow rate of hydrogen gas to the burner 7 is decreased, and the measured value of the surface temperature of the growth part of the glass particulate deposit 19 is lower than the target value. When it is small, it is preferable to increase the flow rate of the hydrogen gas to the burner 7.

この場合、ガラス微粒子堆積体１９の表面温度が大きい場合には、成長速度が小さくなり、外径が太くなる傾向にあるので、水素ガス流量を減少させて表面温度を低くする方向とする。また、ガラス微粒子堆積体１９の表面温度が小さい場合には、成長速度が大きくなり、外径が細くなる傾向にあるので、水素ガス流量を増加させて表面温度を高くする方向とする。   In this case, when the surface temperature of the glass particulate deposit 19 is large, the growth rate tends to decrease and the outer diameter tends to increase, so the hydrogen gas flow rate is decreased to reduce the surface temperature. Further, when the surface temperature of the glass fine particle deposit 19 is small, the growth rate tends to increase and the outer diameter tends to decrease, so the hydrogen gas flow rate is increased to increase the surface temperature.

このように成長速度又は表面温度の目標値を予め設定して水素ガス流量の制御を行う場合、この目標値と、ガラス微粒子堆積体１９の成長速度又は表面温度の計測値との差分を算出し、目標値と計測値との差分がある一定上の範囲となった時に、水素ガス流量を上記のように制御するとよい。   Thus, when the target value of the growth rate or the surface temperature is set in advance and the hydrogen gas flow rate is controlled, the difference between this target value and the measured value of the growth rate or the surface temperature of the glass particulate deposit 19 is calculated. When the difference between the target value and the measured value is in a certain upper range, the hydrogen gas flow rate may be controlled as described above.

以上に説明したように、水素ガス流量を制御することによってガラス微粒子堆積体１９の底面部の表面温度をコントロールすることにより、ガラス微粒子堆積体１９の外径を高精度で均一となるように堆積していくことができ、その結果、外径変動が少なく、しかもばらつきも少ない多孔質ガラス母材を製造することができる。   As described above, by controlling the surface temperature of the bottom surface of the glass fine particle deposit 19 by controlling the hydrogen gas flow rate, the outer diameter of the glass fine particle deposit 19 is deposited with high accuracy and uniformity. As a result, it is possible to manufacture a porous glass base material with little variation in outer diameter and less variation.

また、本実施形態においては、ガラス微粒子堆積体１９の成長速度又は表面温度に基づいて、水素ガス流量を制御する方法について説明したが、同様に他の助燃性ガス（酸素ガス）やガラス原料用ガス等のガス流量を制御することにより、ガラス微粒子堆積体１９の外径を制御することができる。さらに、複数のガス（水素ガス、酸素ガス及びガラス原料用ガスから選択される２種又は３種）の流量を同時に制御してもよい。
例えば、酸素ガスの流量を制御する場合、ガラス微粒子堆積体の成長速度１９の計測値が目標値より大きいときに、バーナ７への酸素ガスの流量を減量制御し、ガラス微粒子堆積体１９の成長速度の計測値が目標値より小さいときに、バーナ７への酸素ガスの流量を増量制御するとよい。
表面温度に基づいて酸素ガス流量を制御する場合は、ガラス微粒子堆積体１９の表面温度の計測値が目標値より大きいときに、バーナ７への酸素ガスの流量を増量制御し、ガラス微粒子堆積体１９の表面温度の計測値が目標値より小さいときに、バーナへの酸素ガスの流量を減量制御するとよい。 In the present embodiment, the method of controlling the hydrogen gas flow rate based on the growth rate or surface temperature of the glass particulate deposit 19 has been described. Similarly, for other auxiliary combustible gas (oxygen gas) and glass raw material. By controlling the flow rate of the gas or the like, the outer diameter of the glass particulate deposit 19 can be controlled. Furthermore, the flow rates of a plurality of gases (two or three selected from hydrogen gas, oxygen gas, and glass raw material gas) may be controlled simultaneously.
For example, when the flow rate of the oxygen gas is controlled, when the measured value of the growth rate 19 of the glass particulate deposit is larger than the target value, the flow rate of the oxygen gas to the burner 7 is controlled to decrease, and the glass particulate deposit 19 grows. When the measured speed value is smaller than the target value, the flow rate of the oxygen gas to the burner 7 may be increased.
When the oxygen gas flow rate is controlled based on the surface temperature, when the measured value of the surface temperature of the glass fine particle deposit 19 is larger than the target value, the flow rate of oxygen gas to the burner 7 is increased and controlled. When the measured value of the surface temperature of 19 is smaller than the target value, the flow rate of oxygen gas to the burner may be controlled to be reduced.

また、ガラス原料用ガスの流量を制御する場合は、ガラス微粒子堆積体１９の成長速度の計測値が目標値より大きいときに、バーナ７へのガラス原料用ガスの流量を減量制御し、ガラス微粒子堆積体１９の成長速度の計測値が目標値より小さいときに、バーナ７へのガラス原料用ガスの流量を増量制御するとよい。
表面温度に基づいてガラス原料用ガス流量を制御する場合は、ガラス微粒子堆積体１９の表面温度の計測値が目標値より大きいときに、バーナ７へのガラス原料用ガスの流量を減量制御し、ガラス微粒子堆積体１９の表面温度の計測値が目標値より小さいときに、バーナへのガラス原料用ガスの流量を増量制御するとよい。 Further, when the flow rate of the glass raw material gas is controlled, when the measured value of the growth rate of the glass fine particle deposit 19 is larger than the target value, the flow rate of the glass raw material gas to the burner 7 is reduced and controlled. When the measured value of the growth rate of the deposit 19 is smaller than the target value, the flow rate of the glass raw material gas to the burner 7 should be increased.
When controlling the glass raw material gas flow rate based on the surface temperature, when the measured value of the surface temperature of the glass particulate deposit 19 is larger than the target value, the flow control of the glass raw material gas flow to the burner 7 is reduced. When the measured value of the surface temperature of the glass particulate deposit 19 is smaller than the target value, the flow rate of the glass raw material gas to the burner may be increased.

なお、本発明に係る多孔質ガラス母材の製造方法は、上記で述べた実施形態に限定されるものではなく、適宜な変形、改良等が可能である。例えば、上記実施形態においては、バーナ７を１本用いた例を示したが、バーナの本数は１本に限定されず、複数本用いた場合にも本発明は適用可能である。   In addition, the manufacturing method of the porous glass base material based on this invention is not limited to embodiment described above, A suitable deformation | transformation, improvement, etc. are possible. For example, in the above-described embodiment, an example in which one burner 7 is used has been described. However, the number of burners is not limited to one, and the present invention can be applied to the case where a plurality of burners are used.

以下、実施例及び比較例を挙げて本発明についてさらに詳しく説明するが、本発明は以下の実施例に限定されるものではない。
（実施例１）
図１に示すＶＡＤ法による製造装置１０を用いて、ガラス棒１１の引き上げ速度の目標値を６０ｍｍ／ｈに設定して、外径１５０ｍｍ、長さ５００ｍｍの多孔質ガラス母材を製造した。すなわち、点Ｐをガラス微粒子堆積体１９の中心から７５ｍｍの距離にある点に設定し、ガラス微粒子堆積体１９の点Ｐを投光器２及び受光器３を用いてモニタした。この堆積量のデータから制御装置４にて点Ｐの成長速度を計測し、この成長速度の増減に応じて、ガラス棒１１の引き上げ速度を増減させた。さらに、制御装置４にて、点Ｐでのガラス微粒子の成長速度の５分間のデータを移動平均して、この移動平均した成長速度が、目標値（６０ｍｍ／ｈ）よりも１％速くなると水素ガス流量を５％増加させ、１％遅くなると水素ガス流量を５％減少させた。
この結果、図２（ａ）の実線に示すように、このガラス微粒子堆積体１９の点Ｐでの成長速度、即ち吊り下げ装置１３によるガラス棒１１の引き上げ速度は、目標値から±３％以内に収まっていた。また、得られた多孔質ガラス母材の外径について調べたところ、図２（ｃ）の実線に示すように、長手方向の変動が目標値の３％以内に収まっていることがわかった。また、上記と同様の方法により多孔質ガラス母材を３本製造したところ、すべての多孔質ガラス母材を、目標値の成長速度に対して±３％以内で製造することができ、外径変動も３％以内とすることができた。すなわち、引き上げ速度の変動幅を極力小さくしながら、成長速度に基づいて水素ガス流量を制御することで、外径変動の少ない多孔質ガラス母材が作成できた。 EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not limited to a following example.
(Example 1)
A porous glass base material having an outer diameter of 150 mm and a length of 500 mm was manufactured by using the manufacturing apparatus 10 by the VAD method shown in FIG. 1 and setting the target value of the pulling speed of the glass rod 11 to 60 mm / h. That is, the point P was set at a point 75 mm away from the center of the glass fine particle deposit 19, and the point P of the glass fine particle deposit 19 was monitored using the projector 2 and the light receiver 3. The growth rate of the point P was measured by the control device 4 from the accumulation amount data, and the pulling rate of the glass rod 11 was increased or decreased according to the increase or decrease of the growth rate. Further, the controller 4 performs a moving average of the data on the growth rate of the glass fine particles at the point P for 5 minutes, and when the moving average growth rate becomes 1% faster than the target value (60 mm / h), hydrogen is generated. The gas flow rate was increased by 5%, and the hydrogen gas flow rate was decreased by 5% when it was delayed by 1%.
As a result, as shown by the solid line in FIG. 2A, the growth rate of the glass particle deposit 19 at the point P, that is, the pulling rate of the glass rod 11 by the suspending device 13 is within ± 3% from the target value. It was settled in. Further, when the outer diameter of the obtained porous glass base material was examined, it was found that the fluctuation in the longitudinal direction was within 3% of the target value as shown by the solid line in FIG. In addition, when three porous glass base materials were manufactured by the same method as described above, all the porous glass base materials can be manufactured within ± 3% of the growth rate of the target value, and the outer diameter The fluctuation could be within 3%. That is, a porous glass base material with less fluctuation in outer diameter could be created by controlling the hydrogen gas flow rate based on the growth rate while minimizing the fluctuation range of the pulling rate.

（実施例２）
図１に示すＶＡＤ法による製造装置１０を用いて、ガラス微粒子堆積体１９の表面温度の目標値を８００℃に設定して、外径１５０ｍｍ、長さ５００ｍｍの多孔質ガラス母材を製造した。すなわち、点Ｐをガラス微粒子堆積体１９の中心から７５ｍｍの距離にある点に設定し、ガラス微粒子堆積体１９の点Ｐを投光器２及び受光器３を用いてモニタした。この堆積量のデータから制御装置４にて点Ｐの成長速度を計測し、この成長速度の増減に応じて、ガラス棒１１の引き上げ速度を増減させた。さらに、温度測定器８により点Ｔの表面温度を測定した。
そして、制御装置４にて、この点Ｔの表面温度の５分間のデータを移動平均して、この移動平均した表面温度が、目標値（８００℃）よりも５℃高くなると、水素ガス流量を５％減少させ、温度が５℃低くなると水素ガス流量を５％増加させた。
この結果、図２（ｂ）の実線に示すように、このガラス微粒子堆積体１９の点Ｔでの表面温度は、目標値から±３％以内に収まっていた。また、得られた多孔質ガラス母材の外径について調べたところ、長手方向の変動が目標値の３％以内に収まっていることがわかった。
また、上記と同様の方法により多孔質ガラス母材を３本製造したところ、すべての多孔質ガラス母材で、目標の表面温度に対して±３％以内で製造することができ、外径変動も３％以内とすることができた。すなわち、引き上げ速度の変動幅を極力小さくしながら、表面温度に基づいて水素ガス流量を制御することで、外径変動の少ない多孔質ガラス母材が作製できた。 (Example 2)
A porous glass base material having an outer diameter of 150 mm and a length of 500 mm was manufactured by using the manufacturing apparatus 10 by the VAD method shown in FIG. 1 and setting the target value of the surface temperature of the glass fine particle deposit 19 to 800 ° C. That is, the point P was set at a point 75 mm from the center of the glass fine particle deposit 19, and the point P of the glass fine particle deposit 19 was monitored using the projector 2 and the light receiver 3. The growth rate of the point P was measured by the control device 4 from the accumulation amount data, and the pulling rate of the glass rod 11 was increased or decreased according to the increase or decrease of the growth rate. Further, the surface temperature of the point T was measured by the temperature measuring device 8.
Then, the controller 4 performs a moving average of the data of the surface temperature at this point T for 5 minutes, and when the moving average surface temperature becomes 5 ° C. higher than the target value (800 ° C.), the hydrogen gas flow rate is changed. When the temperature decreased by 5% and the temperature decreased by 5 ° C., the hydrogen gas flow rate was increased by 5%.
As a result, as shown by the solid line in FIG. 2B, the surface temperature of the glass fine particle deposit 19 at the point T was within ± 3% from the target value. Further, when the outer diameter of the obtained porous glass base material was examined, it was found that the longitudinal variation was within 3% of the target value.
In addition, when three porous glass base materials were manufactured by the same method as described above, all the porous glass base materials can be manufactured within ± 3% of the target surface temperature, and the outer diameter variation Was also within 3%. That is, a porous glass base material with little fluctuation in outer diameter could be produced by controlling the hydrogen gas flow rate based on the surface temperature while minimizing the fluctuation range of the pulling rate.

（比較例１）
実施例１と同様に図１に示す製造装置１０を用いて、多孔質ガラス母材を製造した。すなわち、ガラス微粒子堆積体１９の点Ｐを投光器２及び受光器３を用いてモニタしながら、この堆積量のデータから制御装置４にて点Ｐの成長速度を計測し、この成長速度の増減に応じて、ガラス棒１１の引き上げ速度のみを増減させた。ただし、燃焼用ガス及びガラス原料用ガスのいずれのガス流量の増減を行わず、一定とした。
その結果、図２（ａ）、（ｂ）の破線に示すように、成長速度及び表面温度が変動し、図２（ｃ）の破線に示すように長手方向に外径が変動した。また、同様の方法により母材を３本製造したところ、１本の母材の成長速度、表面温度及び外径が変動するだけでなく、３本の母材の成長速度、表面温度及び外径もばらついていた。 (Comparative Example 1)
As in Example 1, a porous glass base material was manufactured using the manufacturing apparatus 10 shown in FIG. That is, while monitoring the point P of the glass fine particle deposit 19 using the projector 2 and the light receiver 3, the control device 4 measures the growth rate of the point P from the deposition amount data, and increases or decreases the growth rate. Accordingly, only the pulling speed of the glass rod 11 was increased or decreased. However, the flow rate of either the combustion gas or the glass raw material gas was not increased or decreased, and was kept constant.
As a result, the growth rate and surface temperature fluctuated as indicated by the broken lines in FIGS. 2A and 2B, and the outer diameter varied in the longitudinal direction as indicated by the broken lines in FIG. In addition, when three base materials were manufactured by the same method, not only the growth rate, surface temperature and outer diameter of one base material changed, but also the growth speed, surface temperature and outer diameter of the three base materials. It was scattered.

ＶＡＤ法による多孔質ガラス母材の製造装置の一実施形態を示しており、（ａ）は概略正面図、（ｂ）は底面から見た図を示している。1 shows an embodiment of an apparatus for producing a porous glass base material by the VAD method, wherein (a) is a schematic front view, and (b) is a view seen from the bottom. 本実施例における結果を示すグラフであり、（ａ）は多孔質ガラス母材の製造中の母材長に対する引き上げ速度、（ｂ）は多孔質ガラス母材の製造中の母材長に対する表面温度、（ｃ）は得られた多孔質ガラス母材の母材長に対する外径の変動を示している。It is a graph which shows the result in a present Example, (a) is the raising speed with respect to the base material length in manufacture of a porous glass base material, (b) is the surface temperature with respect to the base material length in manufacture of a porous glass base material. (C) has shown the fluctuation | variation of the outer diameter with respect to the base material length of the obtained porous glass base material. 従来のＶＡＤ法による多孔質ガラス母材の製造装置の一実施形態を示している。1 shows an embodiment of an apparatus for producing a porous glass base material by a conventional VAD method.

符号の説明Explanation of symbols

４ 制御装置
７ バーナ
１１ ガラス棒
１３ 吊り下げ装置
１９ ガラス微粒子堆積体 4 Control device 7 Burner 11 Glass rod 13 Suspension device 19 Glass particulate deposit

Claims (3)

燃焼用ガスとガラス原料用ガスとをバーナに供給してガラス微粒子を生成させ、ガラス棒を軸回転させながら引き上げ、前記ガラス微粒子を前記ガラス棒の外周に堆積させて多孔質ガラス母材を形成する多孔質ガラス母材の製造方法であって、
前記ガラス棒に堆積したガラス微粒子堆積体成長部の成長速度の計測値又は表面温度の計測値に基づいて、前記バーナに供給する燃焼用ガス及びガラス原料用ガスの少なくともいずれかの流量を制御することを特徴とする多孔質ガラス母材の製造方法。 A combustion gas and a glass raw material gas are supplied to a burner to generate glass particles, and the glass rod is pulled up while rotating the shaft, and the glass particles are deposited on the outer periphery of the glass rod to form a porous glass base material. A method for producing a porous glass preform,
The flow rate of at least one of the combustion gas and the glass raw material gas supplied to the burner is controlled based on the measured value of the growth rate of the glass particulate deposit growing part deposited on the glass rod or the measured value of the surface temperature. The manufacturing method of the porous glass base material characterized by the above-mentioned. 予め前記ガラス微粒子堆積体の成長速度の目標値を設定し、
前記ガラス微粒子堆積体成長部の成長速度の計測値が前記目標値より大きいときに、前記バーナへ供給する水素ガスの流量を増加させ、
前記ガラス微粒子堆積体成長部の成長速度の計測値が前記目標値より小さいときに、前記バーナへ供給する水素ガスの流量を減少させることを特徴とする請求項１に記載の多孔質ガラス母材の製造方法。 Set a target value for the growth rate of the glass particulate deposit beforehand,
When the measured value of the growth rate of the glass particulate deposit growth portion is larger than the target value, the flow rate of hydrogen gas supplied to the burner is increased,
2. The porous glass base material according to claim 1, wherein a flow rate of hydrogen gas supplied to the burner is decreased when a measured value of a growth rate of the glass particulate deposit growth portion is smaller than the target value. Manufacturing method. 予め前記ガラス微粒子堆積体の表面温度の目標値を測定し、
前記ガラス微粒子堆積体成長部の表面温度の計測値が前記目標値より大きいときに、前記バーナへ供給する水素ガスの流量を減少させ、
前記ガラス微粒子堆積体成長部の表面温度の計測値が前記目標値より小さいときに、前記バーナへ供給する水素ガスの流量を増加させることを特徴とする請求項１に記載の多孔質ガラス母材の製造方法。 Measure the target value of the surface temperature of the glass particulate deposit beforehand,
When the measured value of the surface temperature of the glass particulate deposit growth part is larger than the target value, the flow rate of hydrogen gas supplied to the burner is decreased,
2. The porous glass base material according to claim 1, wherein the flow rate of hydrogen gas supplied to the burner is increased when the measured value of the surface temperature of the glass particulate deposit body growth portion is smaller than the target value. Manufacturing method.
JP2003307810A 2003-08-29 2003-08-29 Method of manufacturing porous glass preform Pending JP2005075682A (en)

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JP2008169078A (en) * 2007-01-11 2008-07-24 Sumitomo Electric Ind Ltd Method of manufacturing glass fine particle deposited body
JP2010042983A (en) * 2008-07-18 2010-02-25 Shin-Etsu Chemical Co Ltd Optical fiber preform production method and optical fiber preform production device
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JP2011063491A (en) * 2009-09-18 2011-03-31 Sumitomo Electric Ind Ltd Method for manufacturing synthetic quartz glass preform, and synthetic quartz glass preform
JP2014091645A (en) * 2012-11-01 2014-05-19 Shinetsu Quartz Prod Co Ltd Method for manufacturing synthetic quartz glass soot body, and method for manufacturing transparent synthetic quartz glass ingot
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