JP2005162511A - Glass preform for optical fiber and its manufacturing method - Google Patents
Glass preform for optical fiber and its manufacturing method Download PDFInfo
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- JP2005162511A JP2005162511A JP2003401425A JP2003401425A JP2005162511A JP 2005162511 A JP2005162511 A JP 2005162511A JP 2003401425 A JP2003401425 A JP 2003401425A JP 2003401425 A JP2003401425 A JP 2003401425A JP 2005162511 A JP2005162511 A JP 2005162511A
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- C03—GLASS; MINERAL OR SLAG WOOL
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- 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
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- C03B37/01228—Removal of preform material
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Abstract
Description
本発明は、光ファイバの原材料として使用される光ファイバ用ガラス母材及びその製造方法、特には研削加工による形状修正技術に関する。 The present invention relates to an optical fiber glass base material used as a raw material of an optical fiber and a manufacturing method thereof, and particularly to a shape correction technique by grinding.
光ファイバは、太径のガラス母材(母材インゴット)から成形したガラスロッド、いわゆる光ファイバプリフォームを線引きして製造される。この母材インゴットは、軸付け法や外付け法と呼ばれる方法で多孔質ガラス母材(以下、スート体と称する)を製造し、それを熱処理し透明ガラス化して得られる。この太径のスート体の製造について、その生産性を上げるために様々な提案がなされている。 An optical fiber is manufactured by drawing a glass rod formed from a large-diameter glass base material (base material ingot), a so-called optical fiber preform. This base material ingot is obtained by manufacturing a porous glass base material (hereinafter referred to as a soot body) by a method called a shaft attachment method or an external attachment method, and heat-treating it to form a transparent glass. Various proposals have been made to increase the productivity of the soot body having a large diameter.
その中で、複数のガラス微粒子生成用バーナー(以下、堆積用バーナーと称する)を出発部材であるコア材に沿って部分的に往復移動させ、高速で堆積する方法が提案されている(部分トラバース法)(例えば、特許文献１参照)。この方法は、従来の光ファイバ母材として有効となる部分を超えてバーナーを往復移動させる方法(全域トラバース法)に対して、利用できない不要部を増やすことなくバーナーの本数が増やせ、堆積速度を飛躍的に増大させることができる。 Among them, a method has been proposed in which a plurality of glass particulate generation burners (hereinafter referred to as deposition burners) are partially reciprocated along a core material as a starting member to deposit at a high speed (partial traverse). Law) (for example, refer to Patent Document 1). This method increases the number of burners without increasing the number of unnecessary parts that cannot be used, and increases the deposition rate compared to the conventional method of reciprocating the burner beyond the part that is effective as an optical fiber preform (global traverse method). It can be increased dramatically.
しかしながら、上記部分トラバース法は、堆積速度が飛躍的に増す反面、最終製品である光ファイバの製造に利用可能な有効部分内でバーナーが折り返すために、長手方向の堆積量が不均一になる問題がある。この対策として特許文献１は、折返し位置を順次ずらし、折返し位置の重複による不均一な堆積を解消する方法を採っている。 However, the partial traverse method dramatically increases the deposition rate, but the burner folds back within the effective portion that can be used to manufacture the final product, an optical fiber, resulting in a non-uniform deposition amount in the longitudinal direction. There is. As a countermeasure against this, Patent Document 1 adopts a method in which the folding positions are sequentially shifted to eliminate uneven deposition due to overlapping of the folding positions.
スート体の外径変動を軽減するために、堆積中、外径変動を計測し、堆積量調整用バーナーを用いて外径を補正する方法（特許文献２参照）や、折り返し位置の分散に関与するバーナーの移動距離を制御する方法（特許文献３参照）、堆積用バーナーに供給されるガスをバーナー個々に制御する方法（特許文献４参照）などが提案されている。他にも、堆積用バーナーの堆積量に起因する外径変動について、圧力溜めを利用する方法(特許文献５参照) や、堆積用バーナ毎の堆積量のばらつきを軽減する方法 (特許文献６参照) など、様々な方法が提案されている。 In order to reduce the outer diameter fluctuation of the soot body, the outer diameter fluctuation is measured during the deposition, and the outer diameter is corrected by using a burner for adjusting the deposition amount (see Patent Document 2), and the dispersion of the folding position is involved. A method of controlling the moving distance of the burner (see Patent Document 3) and a method of individually controlling the gas supplied to the deposition burner (see Patent Document 4) have been proposed. In addition, with respect to fluctuations in the outer diameter caused by the deposition amount of the deposition burner, a method using a pressure reservoir (see Patent Document 5), or a method of reducing variations in the deposition amount of each deposition burner (see Patent Document 6) Various methods have been proposed.
これらの外径変動を軽減させる方法を用いても、細かい表面の凹凸は完全には除去できず、また焼結・透明ガラス化時に生じるスート体の収縮の仕方により、得られる母材インゴットの内部構造(コア・クラッド比)が設計値からずれてしまうという問題が発生する。 Even if these methods of reducing the outer diameter fluctuation are used, the fine irregularities on the surface cannot be completely removed, and the inside of the base material ingot obtained depends on the soot body shrinkage that occurs during sintering and transparent vitrification. There is a problem that the structure (core / cladding ratio) deviates from the design value.
また、線引き装置の大型化やコストダウンの要求などにより、近年、母材インゴットは大型化される傾向にある。大型化のメリットとしては、装置への取り付け、工程間を行き来するワークの減少や設備台数の減少による作業員の少人数化、製品の単位重量当りに対する設備費の圧縮などが挙げられるが、デメリットとして、１ロットの重量が増えることからＮＧが出た場合の損失が大きい。 Further, in recent years, base material ingots tend to be increased in size due to an increase in the size of a drawing device and a request for cost reduction. Advantages of increasing the size include mounting on equipment, reducing the number of workers by reducing the number of workpieces going back and forth between processes, reducing the number of equipment, and reducing equipment costs per unit weight of the product. As a result, since the weight of one lot increases, the loss when NG occurs is large.
その他にも、ガラス微粒子堆積時に、堆積層の重量増によって出発部材であるコア材がたわんだり、収縮する堆積層の厚みが増えるため、焼結・透明ガラス化時に周方向で不均一に収縮し、コアが母材インゴットの中心からずれた「偏芯」を起こしやすい。この偏芯は、製品として得られる光ファイバにも残り、光ファイバ同士を接続する際、コア位置がずれ、接続ロスが発生する。 In addition, since the core material, which is the starting member, bends due to the increased weight of the deposited layer or the thickness of the shrinking deposited layer increases when the glass particulates are deposited, it shrinks unevenly in the circumferential direction during sintering and transparent vitrification. , The core tends to cause “eccentricity” deviating from the center of the base material ingot. This eccentricity also remains in the optical fiber obtained as a product, and when connecting the optical fibers, the core position shifts and connection loss occurs.
この対策として、母材インゴットの内部構造(コア・クラッド比)をプリフォームアナライザーや偏光板を用いた計測器などを使用して計測し、得られた結果から母材インゴットの長手方向に対する内部構造(コア・クラッド比)の一定化や、母材インゴット表面の凹凸を除去するために、円筒研削が行なわれている。母材インゴットの円筒研削方法については、特許文献７〜９などで提案されている。
これらの特許文献では、主に表面の凹凸除去と偏芯の修正方法について記載されており、その他に内部構造に依存するカットオフ波長の修正についても記載されている。
As a countermeasure, the internal structure (core / cladding ratio) of the base material ingot is measured using a preform analyzer or a measuring instrument using a polarizing plate, and the internal structure in the longitudinal direction of the base material ingot is obtained from the obtained results. Cylindrical grinding is performed to make the (core / cladding ratio) constant and to remove irregularities on the surface of the base material ingot. The cylindrical grinding method of the base material ingot is proposed in Patent Documents 7 to 9 and the like.
These patent documents mainly describe a method for removing irregularities on the surface and correcting for eccentricity, and also describe correction for a cutoff wavelength depending on the internal structure.
通常、母材インゴットの円筒研削の手順は、先ず、母材の外径、コア及びクラッドの内部構造を計測し、それを修正するための設計を行う。次いで、粗研削、仕上げ研削となる。研削を２段階で行うのは、研削量が多い場合に、荒い砥石で早く目標径に仕上げ、この荒い砥石で発生した深い傷を仕上げ研削で除去し、細かく浅い傷のみにして表面をできるだけ速やかに平滑に仕上げるためである。このため、仕上げ研削は１回ではなく、荒い砥石による研削痕の深さに応じて、複数回仕上げ研削用の砥石で研削している。 Usually, in the procedure of cylindrical grinding of the base material ingot, first, the outer diameter of the base material, the internal structure of the core and the clad are measured, and a design for correcting it is performed. Next, rough grinding and finish grinding are performed. Grinding is performed in two stages. When the grinding amount is large, the target diameter is quickly finished with a rough grindstone, deep scratches generated by this rough grindstone are removed by finish grinding, and only the fine and shallow flaws are used to make the surface as quick as possible. This is because the finish is smooth. For this reason, the finish grinding is not performed once, but is ground with a grindstone for finish grinding a plurality of times according to the depth of the grinding mark by the rough grindstone.
仕上げ研削後、母材インゴットは、プリフォームと呼ばれる光ファイバの前駆体に加工される。このとき、母材インゴットが細い場合は、端部加工処理を行った後に表面の火炎研磨が行なわれる。母材インゴットが太い場合には、所定の径と長さに延伸加工後、吊り下げ用ダミー棒の接続と火炎研磨を行い、線引き装置にセットされる。実際の円筒研削による仕上げ研削の状態は、その火炎研磨後に研削痕が残らない程度に仕上げられる。 After the finish grinding, the base material ingot is processed into an optical fiber precursor called a preform. At this time, when the base material ingot is thin, the surface is subjected to flame polishing after the end portion processing. When the base material ingot is thick, after extending to a predetermined diameter and length, the suspension dummy rod is connected and flame-polished and set in the wire drawing device. The actual state of finish grinding by cylindrical grinding is finished to the extent that no grinding marks remain after the flame polishing.
従来、円筒研削による仕上げ研削は、母材インゴットの外径が小さいときは、６００メッシュ(以下、＃６００と記す)のダイアモンド砥粒が埋め込まれた砥石を使用して行なわれていたが、母材インゴットの外径が大きくなるにつれ、従来条件ではうまく研削できないようになってきた。 Conventionally, finish grinding by cylindrical grinding has been performed using a grindstone embedded with 600 mesh (hereinafter referred to as # 600) diamond abrasive grains when the outer diameter of the base material ingot is small. As the outer diameter of the material ingot increases, it has become impossible to grind well under conventional conditions.
具体的には、研削面積が大きくなるため、砥石が目詰まりし易く、そのため切り込み量が浅くなる。また研削送り速度を遅くしないと火花が発生し、母材インゴットの表面に傷が発生するようになった。砥石の目詰まりを防ぐには、母材インゴットの回転数を落とす、砥石の切り込み量を減らす、砥石送り速度（母材の長手方向に沿っての砥石の移動速度）を遅くするなどの方法が挙げられるが、いずれも研削に要する時間が増す方向にある。 Specifically, since the grinding area becomes large, the grindstone is likely to be clogged, and therefore the cutting depth becomes shallow. In addition, if the grinding feed rate was not slowed, sparks occurred and scratches occurred on the surface of the base material ingot. To prevent clogging of the grindstone, there are methods such as reducing the rotation speed of the base material ingot, reducing the cutting amount of the grindstone, and slowing the grindstone feed speed (the grindstone movement speed along the longitudinal direction of the base material). Although it is mentioned, all are in the direction which the time which grinding requires increases.
母材インゴットの外径が１３０ｍｍ程度の場合は、＃６００のダイアモンド砥石による仕上げ研削で、ワーク回転数１０ｒｐｍ、切り込み量０．０５ｍｍ、砥石送り速度２０ｍｍ/ｍｉnの条件で、良好な表面状態が得られていた。これが母材インゴットの大型化で、外径が１６０ｍｍを超えるものに対しても同じ条件で研削を行うと、周速度の上昇と研削面積の増大により、砥石が目詰まりを起こしやすく、火花の発生などにより研削できなかったり、逆に表面に傷を生じることがあった。そこで目詰まりの起こりにくい条件で研削を行うと、十分な表面仕上げ状態を得るための所要時間が長くなるという、問題があった。 When the outer diameter of the base material ingot is about 130 mm, a good surface condition can be obtained by finish grinding with a # 600 diamond grinding wheel under the conditions of a workpiece rotation speed of 10 rpm, a cutting depth of 0.05 mm, and a grinding wheel feed speed of 20 mm / min. It was done. This is an increase in the size of the base material ingot. If grinding is performed under the same conditions for those with an outer diameter exceeding 160 mm, the grinding wheel is likely to be clogged due to an increase in peripheral speed and an increase in the grinding area. In some cases, the surface could not be ground or the surface could be scratched. Therefore, when grinding is performed under conditions where clogging is unlikely to occur, there is a problem that the time required to obtain a sufficient surface finish state becomes long.
この研削時に生じた傷は、次工程の火炎研磨では消えにくく、より火力の強力な火炎研磨を行なわねばならなかった。火炎研磨の火力を強くする方法には、酸水素炎のガス量を増やす方法と、バーナーの移動速度を遅くして、母材インゴットへの単位長さあたりの供給熱量を増やす方法があるが、これらの方法は、使用ガスの増大と生産性の低下を招く。このため、火炎研磨の負荷を小さくするために、適度に平滑化された表面状態が研削後の母材インゴットに求められる。 The scratches generated during this grinding were difficult to disappear in the next process of flame polishing, and it was necessary to perform flame polishing with more powerful heat. There are two methods for increasing the flame power of flame polishing: one is to increase the gas amount of the oxyhydrogen flame, and the other is to increase the amount of heat supplied per unit length to the base material ingot by slowing the moving speed of the burner. These methods lead to an increase in gas used and a decrease in productivity. For this reason, in order to reduce the load of flame polishing, a moderately smooth surface state is required for the base material ingot after grinding.
本発明は、母材インゴットの表面を高速で円筒研削を行うことができ、かつ次工程で問題となる研削傷の無い光ファイバ用ガラス母材及びその製造方法を提供することを目的としている。 An object of the present invention is to provide a glass base material for optical fibers that can perform cylindrical grinding of the surface of a base material ingot at a high speed and is free from grinding scratches that will be a problem in the next process, and a method for manufacturing the same.
母材インゴットの表面状態を円筒研削により、次工程で問題の無い程度に表面状態を高速で仕上げる条件を鋭意実験し調査した結果、母材インゴットが大型化した場合でも高速で形状修正できる方法を見出し、上記課題を解決した。具体的には、本発明の光ファイバ用ガラス母材の製造方法は、ＶＡＤ法で作製したコア材上に、外付け法にてガラス微粒子を堆積させた後、加熱・溶融して脱水・透明ガラス化し、得られたガラス母材の表面に生じた凹凸を研削して光ファイバ用ガラス母材を製造する方法において、粗研削後、最後の仕上げ研削を＃３２５〜４００ダイアモンド砥石を使用して円筒研削を行った後、火炎研磨により研削跡を除去することを特徴としている。 As a result of diligent experiments and investigations on conditions to finish the surface condition at high speed to the extent that there is no problem in the next process by cylindrical grinding of the surface condition of the base material ingot, a method that can correct the shape at high speed even when the base material ingot is enlarged is shown. The headline and the above problems were solved. Specifically, the method for producing a glass preform for an optical fiber according to the present invention is such that glass fine particles are deposited by an external method on a core material produced by a VAD method, and then heated, melted and dehydrated / transparent. In the method of manufacturing a glass preform for optical fiber by grinding the irregularities generated on the surface of the glass preform obtained by vitrification, the final finish grinding is performed using a # 325-400 diamond grindstone after rough grinding. After performing cylindrical grinding, the grinding mark is removed by flame polishing.
なお、ガラス母材の内部構造を円筒研削にて修正した後、仕上げ研削を行うものであり、仕上げ研削時の砥石の送り速度は、２５mm/min以下にするのが好ましく、切込み量は０．０５ｍｍ程度とする。
本発明の光ファイバ用ガラス母材は、上記製造方法を用いて製造されたものである。
In addition, after the internal structure of the glass base material is corrected by cylindrical grinding, finish grinding is performed. The feed speed of the grindstone at the time of finish grinding is preferably 25 mm / min or less, and the cutting depth is 0. It is about 05 mm.
The glass preform for optical fiber of the present invention is manufactured using the above manufacturing method.
本発明により、母材インゴットの表面を高速で円筒研削を行うことができ、かつ次工程で問題となる研削傷の無い表面状態が得られる。 According to the present invention, the surface of the base material ingot can be subjected to cylindrical grinding at a high speed, and a surface state free from grinding scratches, which becomes a problem in the next process, can be obtained.
以下、本発明の実施の形態について詳細に説明する。
母材インゴットは、透明ガラス化時に曲がりを生じていることが多く、研削機にセットしたとき、研削機の回転中心と母材インゴットのコアの中心が異なることがある。そのため、セットされた母材インゴットのコアの中心と回転中心とのずれを長手方向にわたって計測し、コア中心に従って研削するように砥石位置を制御する必要がある。
Hereinafter, embodiments of the present invention will be described in detail.
In many cases, the base material ingot is bent during transparent vitrification, and when set in a grinding machine, the center of rotation of the grinding machine and the center of the core of the base material ingot may be different. Therefore, it is necessary to measure the deviation between the center of the core of the set base material ingot and the rotation center in the longitudinal direction and control the position of the grindstone so that grinding is performed according to the center of the core.
図１は、使用した円筒研削機の概略を示している。
母材インゴット１は、装置のチャック支持部２ａ，２ｂに把持具３ａ，３ｂにより支持され、回転モーター４により回転可能に取り付けられている。研削は、母材インゴット１の長手方向に沿って、砥石５を回転させながら移動させることにより、所定量の切り込みが行なわれる。目標とする研削量が多いときは、砥石５を複数回往復移動させることになる。なお、符号６は砥石５の回転軸であり、符号７は移動主軸台、符号８は固定主軸台である。
FIG. 1 shows an outline of the used cylindrical grinding machine.
The base material ingot 1 is supported on
次ぎに、研削方法について、図２を用いて具体的に説明する。
先ず、母材インゴット１の長手方向の複数箇所において、その母材中心Ｏ2とコア中心Ｏ1との偏心量を測定部９で測定し、該偏心量が実質的に０となるようなコア中心Ｏ1を中心とする母材、すなわち目標クラッド１５の目標径Ｔを設計部１０で算出し、制御部１１に記憶させる。
研削時においては、コア中心Ｏ1を中心とする目標クラッド１５が目標径Ｔとなるように、母材インゴット１の長手方向に沿って砥石駆動部１２を制御部１１で制御される。
Next, the grinding method will be specifically described with reference to FIG.
First, at a plurality of locations in the longitudinal direction of the base material ingot 1, the eccentricity between the base material center O 2 and the core center O 1 is measured by the measuring
At the time of grinding, the
(従来例)
ＶＡＤ法により作製され透明ガラス化されたコア材を、所定の外径に延伸して出発部材とし、これにスート付けを行った後、さらに透明ガラス化して、両端がテーパー形状をした、有効部の平均外径が１３０ｍｍで有効部長約１５００ｍｍの母材インゴットを作製した。
(Conventional example)
A core material produced by the VAD method and made into a transparent glass is stretched to a predetermined outer diameter to obtain a starting member, and after sooting, this is further made into a transparent glass, and both ends are tapered. A base material ingot having an average outer diameter of 130 mm and an effective part length of about 1500 mm was produced.
研削は、外径７８ｍｍ、内径６８ｍｍのメタルボンドのカップ型ダイアモンド砥石（以下、単に砥石と称する）を使用し、回転数５０００ｒｐｍで行なった。先ず、＃８０の砥石を用いて切込み量０．９ｍｍの研削を１回、次に、＃２００の砥石で切込み量０．２ｍｍの研削を１回、最後に＃６００の砥石で切込み量０．０５ｍｍの研削を４回行った。 Grinding was performed at a rotational speed of 5000 rpm using a metal bond cup type diamond grindstone (hereinafter simply referred to as a grindstone) having an outer diameter of 78 mm and an inner diameter of 68 mm. First, grinding with a # 80 grindstone is performed once with a cutting depth of 0.9 mm, then grinding with a # 200 grindstone is performed once with a cutting depth of 0.2 mm, and finally with a # 600 grindstone, a cutting depth of 0. The grinding of 05 mm was performed 4 times.
なお、母材インゴットの回転数は８ｒｐｍで、母材インゴットの長手方向に沿っての砥石の送り速度は、＃８０と＃２００の砥石による研削時は４０ｍｍ／ｍｉｎとし、＃６００の砥石による研削時は２０ｍｍ／ｍｉｎとした。このようにして、径方向へ最大研削量２.５ｍｍに達する研削を行った。研削に要した時間は６．５時間であった。
研削の結果は、目詰まりも無く表面状態も良好であった。
The rotation speed of the base material ingot is 8 rpm, and the feed speed of the grinding wheel along the longitudinal direction of the base material ingot is 40 mm / min when grinding with the # 80 and # 200 grinding wheels, and grinding with the # 600 grinding wheel. The time was 20 mm / min. In this way, grinding was performed to reach a maximum grinding amount of 2.5 mm in the radial direction. The time required for grinding was 6.5 hours.
As a result of grinding, there was no clogging and the surface condition was good.
(比較例１)
従来例のものより太い、外径１６０ｍｍの母材インゴットを従来例と同様にして作製し、従来例と同じ条件で研削を実施した。最後に行なった＃６００の砥石による研削の１回目で、研削範囲のほぼ１/３を終えた頃から負荷増により送り速度が低下し、さらに研削範囲の半分を超えたところで火花が発生し、研削続行が不可能となった。母材の表面には、通常の研削痕とは異なる傷が発生しており、修正が必要な状態であった。
(Comparative Example 1)
A base material ingot having an outer diameter of 160 mm thicker than that of the conventional example was produced in the same manner as the conventional example, and was ground under the same conditions as in the conventional example. At the first grinding with the # 600 grinding wheel, the feed speed decreased due to an increase in load from the time when almost 1/3 of the grinding range was completed, and a spark was generated when the grinding range exceeded half. It was impossible to continue grinding. On the surface of the base material, scratches different from normal grinding marks were generated, and correction was necessary.
(比較例２)
外径１６０ｍｍの母材インゴットを従来例と同様にして作製し、従来例と同じ研削機を使用したが、研削条件を変えて研削した。
研削は、まず＃８０の砥石で切込み量０．９ｍｍの研削を１回、次に＃２００の砥石で切込み量０．２ｍｍの研削を１回、最後に＃６００の砥石で切込み量０．０３ｍｍの研削を６回行った。母材インゴットの回転数は８ｒｐｍで、砥石の送り速度はそれぞれ、＃８０と＃２００の砥石による研削時４０ｍｍ／ｍｉｎ、＃６００の砥石による研削時１６ｍｍ／ｍｉｎとした。その他は従来例と同じ条件で研削した。
研削の結果は、目詰まりも無く表面状態も良好であったが、研削に従来例の倍近い１１時間を要した。
(Comparative Example 2)
A base material ingot having an outer diameter of 160 mm was produced in the same manner as in the conventional example, and the same grinding machine as in the conventional example was used, but grinding was performed under different grinding conditions.
Grinding is performed first with a # 80 grindstone with a cutting depth of 0.9 mm, then with a # 200 grindstone once with a cutting depth of 0.2 mm, and finally with a # 600 grindstone with a depth of cut of 0.03 mm. Was ground 6 times. The rotation speed of the base material ingot was 8 rpm, and the feeding speed of the grindstone was 40 mm / min when grinding with a # 80 and # 200 grindstone, and 16 mm / min when grinding with a # 600 grindstone, respectively. Others were ground under the same conditions as in the conventional example.
As a result of grinding, although clogging was not found and the surface condition was good, grinding took 11 hours, which was nearly twice that of the conventional example.
同様に外径１６０ｍｍの母材インゴットを使用し、＃６００の砥石を使用した最後の仕上げ研削の条件をいろいろ試した結果（Ａ，Ｂ）を、先の従来例、比較例１，２の結果とともに表１に示した(表には変えた条件のみ示す)。
表１より、母材インゴットの外径が１６０ｍｍになると、従来例の外径１３０ｍｍの母材インゴットで行えていた研削条件では、うまく研削を行えないことがわかり、比較例２のように極端に研削速度が落ち、研削に長時間を要する。
Similarly, using the base material ingot with an outer diameter of 160 mm, the results of various final grinding conditions using a # 600 grindstone (A, B) are the results of the previous conventional example and the comparative examples 1 and 2. The results are shown in Table 1 (only the changed conditions are shown in the table).
From Table 1, it can be seen that when the outer diameter of the base material ingot is 160 mm, grinding cannot be performed well under the grinding conditions that were performed with the base material ingot with the outer diameter of 130 mm of the conventional example. Grinding speed decreases and grinding takes a long time.
外径１６０ｍｍの母材インゴットを比較例と同様にして作製し、同じ研削機で本発明による研削方法を実施した。研削は、先ず＃８０の砥石で切込み量０.９ｍｍを１回、次に＃２００の砥石で切込み量０.２ｍｍを１回、最後に＃４００の砥石で切込み量０.０５ｍｍを４回実施した。母材インゴットの回転数は８ｒｐｍで、砥石の送り速度はそれぞれ、＃８０と＃２００時４０ｍｍ／ｍｉｎ、＃４００時２４ｍｍ／ｍｉｎとした。砥石は、外径７８ｍｍ、内径６８ｍｍのメタルボンドのカップ型砥石を使用し、砥石の回転数を５０００ｒｐｍとした。 A base material ingot having an outer diameter of 160 mm was produced in the same manner as in the comparative example, and the grinding method according to the present invention was carried out using the same grinding machine. Grinding is performed with a # 80 grindstone once with a cutting depth of 0.9 mm, then with a # 200 grindstone once with a cutting depth of 0.2 mm, and finally with a # 400 grindstone with a cutting depth of 0.05 mm four times. did. The rotation speed of the base material ingot was 8 rpm, and the feeding speed of the grindstone was # 80, # 200 hours 40 mm / min, and # 400 hours 24 mm / min, respectively. As the grindstone, a metal bond cup type grindstone having an outer diameter of 78 mm and an inner diameter of 68 mm was used, and the rotation speed of the grindstone was set to 5000 rpm.
研削の結果、目詰まりも無く表面状態も良好であり、次工程の火炎研磨で今まで通りの表面状態が得られた。研削に要した時間は、測定や砥石交換の時間などを除き６時間であり、従来より５時間以上(約１/２)の短縮となった。
同様に外径１６０ｍｍの母材インゴットを使用し、最後の仕上げ研削条件をいろいろ変えた結果（Ａ〜Ｆ）を表２に示した(表には変えた条件のみ示す)。
As a result of grinding, there was no clogging and the surface condition was good, and the surface condition as before was obtained by flame polishing in the next process. The time required for grinding was 6 hours, excluding the time required for measurement and wheel replacement, and was shortened by more than 5 hours (about 1/2) from the conventional method.
Similarly, the results (A to F) of using the base material ingot having an outer diameter of 160 mm and changing the final finish grinding conditions are shown in Table 2 (only the changed conditions are shown in the table).
表２より、従来の＃６００ダイアモンド砥石による仕上げ研削後、火炎研磨して得られる表面状態と同程度の表面状態が、＃４００でも得られ、さらに、表面状態が若干悪くなるため、あまり高速化は期待できないが、＃３２５でも仕上げ研削が可能であることがわかる。
以上のことから、研削後の母材インゴットで表面状態を＃６００などの細かい砥石を使用しなくても、＃３２５〜４００の砥石で十分仕上げ研削が行え、さらに研削速度の高速化が可能であることがわかった。
以上、本発明はこれらに限定されず、様々な態様が可能である。
From Table 2, after finishing grinding with a conventional # 600 diamond grinding wheel, the surface condition equivalent to the surface condition obtained by flame polishing can be obtained even with # 400, and the surface condition becomes slightly worse, so the speed is much higher. However, it can be seen that finish grinding is possible even with # 325.
From the above, it is possible to perform sufficient finish grinding with the # 325-400 grindstone without using a fine grindstone such as # 600 on the ground base material ingot, and further increase the grinding speed. I found out.
As mentioned above, this invention is not limited to these, A various aspect is possible.
本発明によれば、光ファイバの原材料として、研削傷の無い光ファイバ用ガラス母材を短時間で提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the glass preform | base_material for optical fibers without a grinding flaw can be provided in a short time as a raw material of an optical fiber.
１…母材インゴット、
２ａ，２ｂ…チャック支持部、
３ａ，３ｂ…把持具、
４…回転モーター、
５…砥石、
６…回転軸、
７…移動主軸台、
８…固定主軸台、
９…測定部、
１０…設計部、
１１…制御部、
１２…砥石駆動部、
１３…コア、
１４…クラッド、
１５…目標クラッド、
Ｘ…偏心量、
Ｔ…目標径、
Ｏ1…コア中心、
Ｏ2…母材中心。
1 ... Base material ingot,
2a, 2b ... chuck support,
3a, 3b ... gripping tool,
4 ... Rotary motor,
5 ... Whetstone,
6 ... rotating shaft,
7 ... Movement headstock,
8 ... fixed headstock,
9: Measuring section,
10: Design department,
11 ... control unit,
12 ... Wheel driving unit,
13 ... Core,
14 ... clad,
15 ... Target cladding,
X: Eccentricity,
T ... Target diameter,
O 1 ... core core,
O 2 ... Main material center.
Claims (4)
An optical fiber glass preform manufactured using the manufacturing method according to claim 1.
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| JP2003401425A JP2005162511A (en) | 2003-12-01 | 2003-12-01 | Glass preform for optical fiber and its manufacturing method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2020055722A (en) * | 2018-10-04 | 2020-04-09 | 信越化学工業株式会社 | Method for manufacturing optical fiber glass preform |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020055722A (en) * | 2018-10-04 | 2020-04-09 | 信越化学工業株式会社 | Method for manufacturing optical fiber glass preform |
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