JPH06127963A - Production of preform for optical fiber - Google Patents
Production of preform for optical fiberInfo
- Publication number
- JPH06127963A JPH06127963A JP30753192A JP30753192A JPH06127963A JP H06127963 A JPH06127963 A JP H06127963A JP 30753192 A JP30753192 A JP 30753192A JP 30753192 A JP30753192 A JP 30753192A JP H06127963 A JPH06127963 A JP H06127963A
- Authority
- JP
- Japan
- Prior art keywords
- preform
- diameter
- stretching
- optical fiber
- neck
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
- C03B37/01225—Means for changing or stabilising the shape, e.g. diameter, of tubes or rods in general, e.g. collapsing
- C03B37/0124—Means for reducing the diameter of rods or tubes by drawing, e.g. for preform draw-down
- C03B37/01242—Controlling or regulating the down-draw process
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は光ファイバ用プリフォー
ムの製造方法、特には外付けＣＶＤ法やＶＡＤ法などで
作られた光ファイバ用プリフォームを延伸して所定の径
を有する光ファイバ用プリフォームを製造する方法に関
するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical fiber preform, and more particularly to an optical fiber preform having a predetermined diameter obtained by stretching an optical fiber preform produced by an external CVD method or a VAD method. The present invention relates to a method of manufacturing a preform.
【０００２】[0002]
【従来の技術】光ファイバ用プリフォームの製造は、通
常、外付けＣＶＤ法、ＶＡＤ法などで作られた光ファイ
バ用プリフォームを延伸することによって行なわれてお
り、これは例えば図３に示したように、直径がｄである
プリフォーム11のネックダウン部12の外径をレーザー外
径測定器のような外径測定器13で測定し、この測定値に
基づき制御装置14を用いて引取り速度Ｖを制御するため
の制御信号を引取りモーター15に伝え、これにより最終
外径Ｄが一定の範囲にあるプリフォーム16を得るという
方法で行なわれている。2. Description of the Related Art An optical fiber preform is usually manufactured by drawing an optical fiber preform made by an external CVD method, a VAD method or the like, which is shown in FIG. 3, for example. As described above, the outer diameter of the neck-down portion 12 of the preform 11 having the diameter d is measured by the outer diameter measuring instrument 13 such as a laser outer diameter measuring instrument, and the controller 14 is used to draw the measured value based on the measured value. A control signal for controlling the take-up speed V is transmitted to the take-up motor 15, whereby a preform 16 having a final outer diameter D in a certain range is obtained.
【０００３】[0003]
【発明が解決しようとする課題】しかし、この公知の方
法である特定の最終直径Ｄをもつプリフォームを得る場
合には、外径測定器によってネックダウン部の外径を測
定し、これが一定範囲に納まっていても、これを延伸す
ると最終外径Ｄが規定値から外れることが多く、この対
策が求められている。However, in order to obtain a preform having a specific final diameter D, which is a known method, the outer diameter of the neck-down portion is measured by an outer diameter measuring device, and this is within a certain range. Even if the value is in the above range, the final outer diameter D often deviates from the specified value when it is stretched, and a measure against this is required.
【０００４】[0004]
【課題を解決するための手段】本発明はこのような問題
点を解決した光ファイバ用プリフォームの製造方法に関
するものであり、これはネックダウン部の径を測定して
延伸後のプリフォームの外径を制御する光ファイバ用プ
リフォームの延伸方法において、該プリフォームのネッ
クダウン部の長さを延伸前のプリフォームの外径の３倍
以上とすることを特徴とするものである。SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing an optical fiber preform that solves the above problems, and it measures the diameter of a neck-down portion to obtain a preform after stretching. In the method of drawing an optical fiber preform for controlling the outer diameter, the length of the neck-down portion of the preform is set to be three times or more the outer diameter of the preform before drawing.
【０００５】すなわち、本発明者らは最終直径が規定値
を満たすようにする光ファイバ用プリフォームの製造方
法を開発すべく種々検討した結果、延伸処理後のプリフ
ォームの最終直径が延伸処理時のプリフォームのネック
ダウン部の径変化の傾斜、すなわちネックダウン部の長
さに関係することを見出し、この延伸時のプリフォーム
のネックダウン部の長さを延伸前のプリフォームの直径
の 3.0倍以上としたところ、結果として延伸後のプリフ
ォームの最終直径変動を小さな値に納めることができる
ことを確認して本発明を完成させた。以下にこれをさら
に詳述する。That is, the inventors of the present invention have conducted various studies to develop a method for producing a preform for an optical fiber that allows the final diameter to satisfy a specified value. It was found that the slope of the diameter change of the neck-down part of the preform, that is, it relates to the length of the neck-down part, and the length of the neck-down part of the preform at the time of stretching is 3.0 of the diameter of the preform before stretching. The present invention has been completed by confirming that the final diameter fluctuation of the preform after stretching can be set to a small value as a result of making the number of times more than twice. This will be described in more detail below.
【０００６】[0006]
【作用】本発明は光ファイバ用プリフォームの製造方法
に関するものであり、これはネックダウン部の径を測定
して延伸後のプリフォームの外径を制御する光ファイバ
用プリフォームの延伸方法において、該プリフォームの
ネックダウン部の長さを延伸前のプリフォームの外径の
３倍以上とすることを特徴とするものであり、これによ
れば目的とする延伸後のプリフォームの最終外径の変動
を小さな値とすることができるという有利性が与えられ
る。The present invention relates to a method for manufacturing an optical fiber preform, which is a method for drawing an optical fiber preform for measuring the diameter of a neck-down portion to control the outer diameter of the preform after drawing. The length of the neck-down portion of the preform is 3 times or more of the outer diameter of the preform before stretching, and according to this, the final outside of the target preform after stretching. The advantage is given that the variation of the diameter can be small.
【０００７】本発明による光ファイバ用プリフォームの
製造方法は、外付けＣＶＤ法またはＶＡＤ法などで作ら
れた光ファイバ用プリフォームを延伸して所定の最終直
径をもつプリフォームを製造する方法に関するものであ
るが、本発明の方法では延伸されるべきプリフォームに
おけるネックダウン部の長さが延伸前のプリフォームの
外径の３倍以上のものとされる。The method for producing an optical fiber preform according to the present invention relates to a method for producing an optical fiber preform having a predetermined final diameter by stretching an optical fiber preform produced by an external CVD method or a VAD method. However, in the method of the present invention, the length of the neck-down portion in the preform to be stretched is at least 3 times the outer diameter of the preform before stretching.
【０００８】これは図４の（ａ）に示したように、延伸
時にプリフォ−ムにおけるネックダウン部の傾斜、すな
わちプリフォ−ムの直径ｄ2 とネックダウン部の長さｌ
2 との比ｌ2 ／ｄ2 が小さいとき、したがって直径ｄ2
に対して長さｌ2 が短いときには、温度分布の微少な変
化などの外乱によってネックダウン部の位置が変化する
ので、図４の（ｂ）に示したように外径測定器で計測す
る位置によってネックダウン部の外径が大きく変動し、
この測定誤差△ｄ2 によって延伸後のプリフォ−ムの最
終直径Ｄ2 を一定値以内に納めるように制御装置が働く
ため、結果において最終値径Ｄ2 の変動が大きくなると
いうことになる。As shown in FIG. 4 (a), this is the inclination of the neck-down portion in the preform during stretching, that is, the diameter d 2 of the preform and the length l of the neck-down portion.
When the ratio l 2 / d 2 with 2 is small, therefore the diameter d 2
On the other hand, when the length l 2 is short, the position of the neck-down portion changes due to disturbance such as a slight change in temperature distribution, so that the position measured by the outer diameter measuring device as shown in FIG. Causes the outer diameter of the neck-down part to change greatly,
Preform after stretching by the measurement error △ d 2 - since the control device acts as pay-time of the final diameter D 2 within a predetermined value, it comes to variations in the final value diameter D 2 is greater in the results.
【０００９】これに対し、図１の（ａ）に示したよう
に、延伸前のプリフォ−ムのネックダウン部の斜傾、す
なわちプリフォ−ムの直径ｄ1 とネックダウン部の長さ
ｌ1 との比ｌ1 ／ｄ1 が大きいとき、したがって直径ｄ
1 に対して長さｌ1 が長いときには、図１の（ｂ）に示
したようにネックダウン部の外径を外径測定器で計測す
るときの計測誤差△ｄ1 が上記した△ｄ2 にくらべて小
さくなるので、延伸後のプリフォ−ムの最終外径Ｄ1 を
一定値以内の変動に納める制御装置の作動によっても、
この最終外径Ｄ2 の変動を小さくとすることができると
いう効果が与えられる。On the other hand, as shown in FIG. 1A, the neck down portion of the preform before stretching is inclined, that is, the diameter d 1 of the preform and the length l 1 of the neck down portion. When the ratio l 1 / d 1 with
When the length l 1 is longer than 1 , as shown in FIG. 1B, the measurement error Δd 1 when measuring the outer diameter of the neck-down portion with the outer diameter measuring device is Δd 2 described above. Since it becomes smaller than that of the preform, the final outer diameter D 1 of the stretched preform is also controlled by the operation of the control device that keeps the fluctuation within a certain value.
The effect that the fluctuation of the final outer diameter D 2 can be made small is provided.
【００１０】なお、この延伸する前のプリフォ−ムの直
径ｄと延伸時のネックダウンの長さｌとの比についてさ
らに研究を進めた結果、これについてはｌ／ｄが３未満
ではまだ延伸時のプリフォ−ムのネックダウン部の直径
を外径測定器で計測するときの測定誤差△ｄが大きくな
って延伸後のプリフォ−ムの最終直径の変動を一定以
内、例えば１mm以内とすることが難しくなるが、このｌ
／ｄが３以上であればこの△ｄが小さくなり、延伸後の
プリフォ−ムの最終直径の変動を一定値以内の小さな値
にすることができるということが確認されたので、この
ｌ／ｄは３以上とすることが必要とされる。As a result of further research on the ratio of the diameter d of the preform before stretching and the length l of the neck-down during stretching, it was found that when l / d was less than 3, the ratio was still during stretching. When the diameter of the neck-down portion of the preform is measured with an outer diameter measuring device, the measurement error Δd becomes large, and the fluctuation of the final diameter of the preform after stretching can be kept within a certain range, for example, within 1 mm. It ’s difficult, but this l
When / d is 3 or more, this Δd becomes small, and it was confirmed that the fluctuation of the final diameter of the preform after stretching can be made a small value within a certain value, so this l / d Is required to be 3 or more.
【００１１】したがって、本発明においては光ファイバ
用プリフォ−ムの延伸時のネックダウン部の長さｌを延
伸前のプリフォ−ムの外径ｄの３倍以上とすることが必
要とされるのであるが、これによれば延伸時のネックダ
ウン部の直径測定時における直径測定誤差△ｄが小さく
なるので、この直径値にもとづいて出される制御装置か
らの制御信号により、目的とする延伸後のプリフォ−ム
の直径誤差が小さくなるという有利性が与えられる。Therefore, in the present invention, it is necessary that the length l of the neck-down portion when the optical fiber preform is stretched is at least three times the outer diameter d of the preform before stretching. However, according to this, the diameter measurement error Δd at the time of measuring the diameter of the neck-down portion at the time of stretching becomes small. Therefore, the control signal from the control device issued based on this diameter value causes The advantage is that the diameter error of the preform is reduced.
【００１２】また、本発明においては延伸時のプリフォ
ームのネックダウン部の長さが延伸前のプリフォームの
直径の３倍以上とされるのであるが、このネックダウン
部の長さを大きくするためには火炎延伸の場合は火炎の
径を大きくすればよく、またこれを電気炉内で延伸する
場合にはこのヒーター長を長くすればよい。Further, in the present invention, the length of the neck-down portion of the preform at the time of stretching is set to be three times or more the diameter of the preform before stretching, but the length of the neck-down portion is increased. For this purpose, the flame diameter may be increased in the case of flame stretching, and the heater length may be increased in the case of stretching it in an electric furnace.
【００１３】[0013]
【実施例】つぎに本発明の実施例をあげる。 実施例、比較例 図３に示す延伸処理方法を用いて直径50mm、長さ 800mm
のコア用石英ガラスプリフォームを最終直径30mmに延伸
するために、酸水素火炎で加熱してこの際、バーナー火
炎の径を変化してネックダウン部の長さをプリフォーム
径の 1.0、 1.5、2.5、3.0、4.5 倍と変化するようにセット
して延伸したところ、プリフォームの最終外径変動（平
均値）と相対的ネックダウン長（ｌ／ｄ）について図２
に示したとおりの結果が得られた。EXAMPLES Next, examples of the present invention will be given. Examples, Comparative Examples Using the stretching treatment method shown in FIG. 3, diameter 50 mm, length 800 mm
In order to stretch the core quartz glass preform to a final diameter of 30 mm, it is heated with an oxyhydrogen flame, at this time, the diameter of the burner flame is changed and the length of the neck down part is 1.0, 1.5 of the preform diameter, When set and stretched so as to change to 2.5, 3.0, and 4.5 times, the final outer diameter fluctuation (average value) of the preform and the relative neckdown length (l / d) are shown in Fig. 2.
The result as shown in was obtained.
【００１４】すなわち、ｌ／ｄが 1.0、1.5 、2.5 では
ネックダウン部の長さが延伸前のプリフォームの直径の
３倍未満であるために、プリフォームの最終外径変動値
が 2.0mm、0.8mm 、0.5mm となり、必ずしも満足すべき
ものでなかったけれども、このｌ／ｄが 3.0以上のもの
はプリフォームの最終外径変動値はその98％以上が±0.
2mm 以内となり、この方法で製造した20本の平均値は0.
12mmとなった。That is, when l / d is 1.0, 1.5, and 2.5, the length of the neck-down portion is less than 3 times the diameter of the preform before stretching, so that the final outer diameter variation value of the preform is 2.0 mm, It was 0.8 mm and 0.5 mm, which was not always satisfactory, but the final outer diameter fluctuation value of the preform of ± 1 of 3.0 was ± 0 for 98% or more.
It is within 2 mm, and the average value of 20 pieces manufactured by this method is 0.
It became 12 mm.
【００１５】[0015]
【発明の効果】本発明は光ファイバ用プリフォームの製
造方法に関するものであり、これは前記したようにネッ
クダウン部の径を測定して延伸後のプリフォームの外径
を制御する光ファイバ用プリフォームの延伸方法におい
て、該プリフォームのネックダウン部の長さを延伸前の
プリフォームの外径の３倍以上とすることを特徴とする
ものであるが、これによれば延伸時のネックダウン部の
径の測定を誤差を少なくすることができるので、この測
定値にもとづく延伸の自動制御により、延伸後のプリフ
ォームの最終外径変動値を小さく制御することができる
という有利性が与えられる。As described above, the present invention relates to a method for manufacturing an optical fiber preform for an optical fiber, in which the diameter of the neck-down portion is measured to control the outer diameter of the stretched preform. In the method of stretching a preform, the length of the neck-down portion of the preform is set to 3 times or more the outer diameter of the preform before stretching. Since it is possible to reduce the error in the measurement of the diameter of the down portion, there is an advantage that the final outer diameter variation value of the preform after stretching can be controlled to be small by the automatic control of the stretching based on the measured value. To be
【図１】 ａ）は本発明による光ファイバ用プリフォー
ム（ｌ1 ／ｄ1 ＝3.0以上）の縦断面図、ｂ）はその外
径測定変動値△ｄ1 を示したものの縦断面図を示したも
のである。FIG. 1 a) is a longitudinal sectional view of an optical fiber preform according to the present invention (l 1 / d 1 = 3.0 or more), and b) is a longitudinal sectional view showing the outer diameter measurement fluctuation value Δd 1 . It is shown.
【図２】 本発明の実施例、比較例で得られたプリフォ
ームの平均最終外径変動値と相対的ネックダウン長との
関係グラフを示したものである。FIG. 2 is a graph showing a relationship between an average final outer diameter variation value of preforms obtained in Examples and Comparative Examples of the present invention and relative neckdown length.
【図３】 光ファイバ用プリフォーム延伸処理方法の縦
断面図を示したものである。FIG. 3 is a vertical cross-sectional view of a preform stretching treatment method for an optical fiber.
【図４】 ａ）は従来法による光ファイバ用プリフォー
ム（ｌ2 ／ｄ2 ＝3.0未満）の縦断面図、ｂ）はその外
径測定変動値△ｄ2 を示したものの縦断面図を示したも
のである。FIG. 4A is a vertical sectional view of an optical fiber preform (l 2 / d 2 = less than 3.0) according to a conventional method, and b) is a vertical sectional view of the outer diameter measurement fluctuation value Δd 2 . It is shown.
11…延伸前のプリフォーム、12…ネックダウン部、13…
直径測定器、 14…制御装置、15…モーター、
16…延伸後のプリフォーム。11 ... Preform before stretching, 12 ... Neck down part, 13 ...
Diameter measuring device, 14 ... Control device, 15 ... Motor,
16… Preform after stretching.
Claims (1)
リフォームの外径を制御する光ファイバ用プリフォーム
の延伸方法において、該プリフォームのネックダウン部
の長さを延伸前のプリフォームの外径の３倍以上とする
ことを特徴とする光ファイバ用プリフォームの製造方
法。1. A method of drawing a preform for an optical fiber in which the diameter of the neck-down portion is measured to control the outer diameter of the preform after drawing, and the length of the neck-down portion of the preform is set to a value before drawing. A method of manufacturing an optical fiber preform, characterized in that the outer diameter of the reform is three times or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30753192A JP3127176B2 (en) | 1992-10-21 | 1992-10-21 | Manufacturing method of preform for optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30753192A JP3127176B2 (en) | 1992-10-21 | 1992-10-21 | Manufacturing method of preform for optical fiber |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06127963A true JPH06127963A (en) | 1994-05-10 |
| JP3127176B2 JP3127176B2 (en) | 2001-01-22 |
Family
ID=17970215
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30753192A Expired - Lifetime JP3127176B2 (en) | 1992-10-21 | 1992-10-21 | Manufacturing method of preform for optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3127176B2 (en) |
-
1992
- 1992-10-21 JP JP30753192A patent/JP3127176B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JP3127176B2 (en) | 2001-01-22 |
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