JP2004091297A - Method and apparatus for drawing glass - Google Patents

Method and apparatus for drawing glass Download PDF

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JP2004091297A
JP2004091297A JP2002258602A JP2002258602A JP2004091297A JP 2004091297 A JP2004091297 A JP 2004091297A JP 2002258602 A JP2002258602 A JP 2002258602A JP 2002258602 A JP2002258602 A JP 2002258602A JP 2004091297 A JP2004091297 A JP 2004091297A
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outer diameter
glass
measuring device
value
stretching
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JP2004091297A5 (en
Inventor
Kentaro Takeda
武田　健太郎
Yuichi Oga
大賀　裕一
Motonori Nakamura
中村　元宣
Toshihiro Oishi
大石　敏弘
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Sumitomo Electric Industries Ltd
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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
    • C03B37/01205—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

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  • 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)
  • Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To improve the precision of diameter of finished drawn glass by contriving the arrangement of outer diameter measuring devices to measure the diameter of drawn glass on the way of drawing. <P>SOLUTION: Both of a first outer diameter measuring device 65 and a second outer diameter measuring device 66 to measure the outer diameter of glass 41 in drawing are placed at positions between the intermediate position of the length L of a drawn down part 46 of glass 41 and a diameter reducing end in a heating furnace 45. A set outer diameter value for one outer diameter measuring device 65 is set on the basis of measurement results obtained with another outer diameter measuring device 66. The drawing velocity of the glass 41 is controlled on the basis of the difference between the set outer diameter value and an outer diameter value actually measured with the outer diameter measuring device 65. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、加熱炉内に投入されるガラスを延伸するガラスの延伸方法及び装置に関し、特に、延伸するガラスの外径精度を向上させるための改良に関する。
【０００２】
【従来の技術】
図７は、加熱炉内に投入される棒状のガラスを延伸するガラスの延伸装置の従来例を示したものである。
ここに示したガラスの延伸装置２０は、特許第３１８８４０４号に開示されたものである。
棒状のガラス１を加熱軟化させる加熱炉５と、吊り下げたガラス１を加熱炉５内に所定速度Ｖ１で投入する母材供給機構４と、加熱炉５から出たガラス端部を所定速度で引き取る引き取り機構６と、引き取り機構６の引き取り速度Ｖ２を制御する制御装置９及び制御用コンピュータ１０と、生成する延伸体２の最終的な外径を確認するために加熱炉５の外部位置（Ｃ点）に設けられた外径測定器１１と、延伸速度（＝引き取り速度Ｖ２−投入速度Ｖ１）を制御するために加熱炉５内のガラス１の延伸、縮径している部位である引落部１ａの２箇所（Ａ点及びＢ点）に外径測定器７，８を設けている。
【０００３】
外径測定器８の装備位置のＢ点は、延伸、縮径が終了する引落部１ａの終端付近に設定されている。また、外径測定器７の装備位置のＡ点は、最も急激に延伸、縮径が行われる位置で、具体的には、引落部１ａの長さＬのほぼ中間位置（即ち、引落部１ａの終端からＬ／２の距離の位置）に設定されている。
【０００４】
以上の延伸装置２０が実施するガラスの延伸方法は、前述の２つの外径測定器７，８によって、延伸途中の２位置Ａ，Ｂでガラス１の外径を測定し、Ａ位置に配置した外径測定器７における外径設定値を、Ｂ位置に配置した外径測定器８の実測外径値に基づいて修正し、Ａ位置の外径測定器７の実測外径値が修正された外径設定値となるように、制御装置９によって延伸速度を調整することで、仕上がり径の高精度化を図るものである。
【０００５】
一方、上記の特許第３１８８４０４号には、Ａ点で引落部１ａの外径を予め設定された設定値になるように延伸速度を制御するのに、ＰＩＤ制御を組み込む技術も提案されている。
ＰＩＤ制御は、例えば、延伸装置における引き取り速度を実測外径値と目標外径値との差に基づいて制御する場合に、実測外径値と目標外径値との差に応じて単純に比例制御するのではなく、実測外径値と目標外径値との差分に更に積分量と微分量を加味した制御を行うもので、仕上がり径を測定するＣ位置と外径値を実測するＡ位置との間の離間距離に起因するタイミング遅れの補償等に有効である。
【０００６】
【発明が解決しようとする課題】
ところで、前述の延伸装置２０において、加熱炉５内のガラス１の引落部１ａの長さＬは、ガラス１の個体差に応じて変わるのは勿論のこと、同一のガラス１でも、加熱炉５内での加熱による延伸処理の経過に伴って刻々と変化する。そして、引落部１ａの長さＬの変化に伴ってテーパの傾斜角が変わり、引落部１ａの中間位置（引落部１ａの終端からＬ／２の距離の位置）も刻々と移動する。
この引落部１ａの中間位置付近は、僅かに位置がずれただけで大きな外径変化が生じるため、引落部１ａの中間位置の外径を正確に実測するには、外径測定器７の取付け位置Ａを引落部１ａの長さ変化に追従して変位させる調整機構が必要となるが、加熱炉５を構成する炉芯管や断熱材に調整機構取付け用の穴をあけることは困難であり、外径測定器７の取付け位置Ａを引落部１ａの長さ変化に追従して変位させることは現実的ではない。
【０００７】
従って、特許第３１８８４０４号に記載の延伸装置２０では、延伸速度を調整する基準となるＡ位置の実測外径値は、想定していた引落部１ａの中間位置の外径との誤差が大きくなって、また、制御のぶれも生じ、前述したＰＩＤ制御を組み合わせたとしても、延伸体２の仕上がり外径の精度を十分に高めることが難しいという問題が生じた。
【０００８】
そこで、本発明の目的は上記課題を解消することに係り、加熱炉内のガラスの延伸、縮径している引落部の長さ変化で引落部のテーパ形状が変わっても、延伸途中の２位置に配置した各外径測定器が、何れも、測定誤差が少なく、より正確な値として、ガラスの外径測定を行うことができるガラスの延伸方法及び装置を提供することにある。
【０００９】
【課題を解決するための手段】
本発明の上記目的は、請求項１に記載のように、加熱炉内に投入されるガラスを延伸するガラスの延伸方法であって、
前記ガラスが延伸、縮径している部分の長さの略中間部よりも縮径終端側の位置にガラスの外径を検出する２台の外径測定器を順次配置し、
一方の外径測定器で測定された測定結果に基づいて他方の外径測定器の設定外径値を設定すると共に、この設定された設定外径値と前記他方の外径測定器で測定される実測外径値との差に基づいて前記ガラスの延伸速度を制御することを特徴とするガラスの延伸方法により達成される。
【００１０】
また、本発明の上記目的は、請求項２に記載のように、請求項１に記載のガラスの延伸方法において、前記一方の外径測定器を前記縮径終端により近い側に配置した第２の外径測定器として扱い、前記他方の外径測定器を第１の外径測定器として扱い、前記第２の外径測定器で測定される実測外径値と予め第２の外径測定器用に設定された第２の設定外径値とに基づいて前記第１の外径測定器の第１の設定外径値を設定することを特徴とするガラスの延伸方法により達成される。
【００１１】
また、本発明の上記目的は、請求項３に記載のように、請求項２に記載のガラスの延伸方法において、前記第１の設定外径値として、前記第２の外径測定器で測定される実測外径値と予め設定された前記第２の設定外径値との偏差を用いることを特徴とするガラスの延伸方法により達成される。
【００１２】
また、請求項２又は３に記載のガラスの延伸方法において、前記第１の外径測定器の位置を延伸されたガラスの目標外径値の１００．５〜１２０％となる位置に設定すると共に、前記第２の外径測定器の位置を前記目標外径値の１００〜１０５％となる位置に設定すると好ましい。
【００１３】
また、請求項２又は３に記載のガラスの延伸方法において、前記第１の外径測定器と前記第２の外径測定器との離間間隔を、それぞれの検出する実測外径値の差が前記目標外径値の０．５％以上となるように設定すると好ましい。
【００１４】
また、本発明の上記目的は、請求項４に記載のように、請求項２又は３に記載のガラスの延伸方法において、前記第１の設定外径値と前記第１の外径測定器で測定される実測外径値との差に基づいて前記延伸速度をＰＩＤ制御することを特徴とするガラスの延伸方法により達成される。
【００１５】
また、本発明の上記目的は、請求項５に記載のように、加熱炉内に投入されるガラスを延伸するガラスの延伸装置であって、
少なくとも前記ガラスの延伸途中に配置されて、前記ガラスの外径を検出する２台の外径測定器と、これら２台の外径測定器の内、一方の外径測定器で測定された測定結果に基づいて他方の外径測定器の設定外径値を設定すると共に、この設定外径値と前記他方の外径測定器の実測外径値との差に基づいて前記ガラスの延伸速度を制御する制御装置とを備え、
前記２台の外径測定器は、前記ガラスが延伸、縮径している部分の長さの略中間部よりも縮径終端側の位置に装備されていることを特徴とするガラスの延伸装置により達成される。
【００１６】
上記構成のガラスの延伸方法及び装置では、加熱炉内のガラスの延伸途中の２位置に外径測定器を配置するが、各外径測定器の位置は加熱炉内のガラスが延伸、縮径する引落部の長さＬに対して、中間部よりも縮径終端側に寄った位置に設定してある。
このように引落部の中間部よりも縮径終端側に寄った位置では、引落部の長さ変化に伴って引落部のテーパの傾斜角が刻々と変わる場合でも、それぞれの外径測定器の測定位置におけるガラスの外径変化は、引落部の中間部付近で測定する場合と比較すると極めて小さな変化となる。
【００１７】
従って、いずれの外径測定器においても、予め想定した定位置で、測定誤差が少なく、より正確な値として、ガラスの外径測定を行うことができ、その結果、一方の外径測定器の実測外径値のフィードバックによって他方の外径測定器用の設定外径値をより高精度に算出制御することが可能となり、また、他方の外径測定器の実測外径値のフィードバックによってガラスの延伸速度をより高精度に制御することが可能になり、実測外径値に基づく延伸速度制御によって、延伸させたガラスの仕上がり外径の精度向上を図ることができる。
【００１８】
【発明の実施の形態】
以下、本発明に係るガラスの延伸方法及び装置の好適な実施の形態を図面に基づいて詳細に説明する。
図１は、本発明に係るガラスの延伸装置の一実施の形態を示したものである。
この一実施の形態のガラスの延伸装置３０は、ガラス４１を発熱体４３によって加熱軟化させる加熱炉４５と、ガラス４１の上端に一体化されたダミー棒４１ａを把持する上部チャック４７と、この上部チャック４７を加熱炉４５に向かって所定速度で降下させることでガラス４１を加熱炉４５内に投入するガラス供給機構４９と、加熱炉４５から出たガラス下端のダミー棒４１ｂを所定速度で引き取る引き取り機構５１とを備えている。
【００１９】
ガラス供給機構４９は、上部チャック４７を上下動可能に支持する送り移動ボールネジ５２と、送り移動ボールネジ５２を回転駆動するモータ５３とを備えた構成で、モータ５３による送り移動ボールネジ５２の回転速度を制御することで、ガラス４１の投入速度Ｖａを任意に設定可能である。
【００２０】
引き取り機構５１は、ダミー棒４１ｂを把持する下部チャック５５と、この下部チャック５５を上下動可能に支持する引き取り移動ボールネジ５７と、引き取り移動ボールネジ５７を回転駆動するモータ５９とを備えた構成で、モータ５９による引き取り移動ボールネジ５７の回転速度を制御することで、ガラス４１の引き取り速度Ｖｃを任意に設定可能である。
【００２１】
この延伸装置３０は、加熱炉４５に投入されたガラス４１を発熱体４３によって加熱軟化させた状態で、ダミー棒４１ｂを引き取り機構５１によって適宜引き取り速度で引き取ることで、ガラス４１の外径を予め設定した目標外径値に縮径させた延伸体６３を製造する。
【００２２】
加熱炉４５内のガラス４１の延伸途中の２箇所に、ガラス４１の外径を測定する第１の外径測定器６５と、第２の外径測定器６６とを配置している。
図示のように、ガラス４１の延伸、縮径している部分である引落部４６の全長をＬとするとき、第１及び第２の外径測定器６５，６６は、何れも、引落部４６の長さＬの略中間部（引落部４６の縮径終端からＬ／２の距離の位置）よりも縮径終端側の位置に順次固定装備されている。
第２の外径測定器６６の位置は引落部４６の縮径終端付近であり、第１の外径測定器６５の位置は、第２の外径測定器６６から発熱体４３側に距離Ｓだけ離間した位置である。
【００２３】
また、加熱炉４５内の延伸終端における延伸体外径（仕上がり径）を前述した目標外径値に維持するために、ガラス供給機構４９によるガラス４１の加熱炉４５への投入速度Ｖａ及び引き取り機構５１による引き取り速度Ｖｃとを、各外径測定器６５，６６が検出した実測外径値と、各外径測定器６５，６６に設定した第１及び第２の設定外径値とに基づいて制御する制御装置６７を備えている。
【００２４】
制御装置６７は、縮径終端付近に配置された第２の外径測定器６６で測定された実測外径値と、予めこの第２の外径測定器６６用に設定された第２の設定外径値とに基づいて第１の外径測定器６５用の第１の設定外径値を設定すると共に、この第１の設定外径値と第１の外径測定器６５の実測外径値との差に基づいてガラス４１の延伸速度を制御する。
なお、延伸速度とは、引き取り機構５１による引き取り速度から、ガラス供給機構４９による投入速度Ｖａを引いた値である。
【００２５】
この制御装置６７は、図２に示すように、内蔵のＰＩＤ調節器６７ａを有している。
制御装置６７は、第１の外径測定器６５の実測外径値と第１の設定外径値と差（Ｅ１（ｔ））、及び第２の外径測定器６６の実測外径値と第２の設定外径値との差（Ｅ２（ｔ））を算出した後、ＰＩＤ調節器６７ａによって、（Ｅ１（ｔ））及び（Ｅ２（ｔ））を積分量と微分量に応じた制御を組み合わせて調整（ＰＩＤ調節）するＰＩＤ制御を実施して、ガラス供給機構４９によるガラス４１の投入速度Ｖａを算出して、算出した投入速度Ｖａとなるようにガラス供給機構４９の動作を制御することで、延伸体６３の仕上がり径を目標外径値に維持する。
【００２６】
以上の構成の延伸装置３０が実施するガラスの延伸方法では、加熱炉４５内のガラス４１の延伸途中の２位置に外径測定器６５，６６を配置するが、各外径測定器６５，６６の位置は加熱炉４５内のガラス４１が延伸、縮径する引落部４６の長さＬに対して、中間部よりも縮径終端側に寄った位置に設定してある。
このように引落部４６の中間部よりも縮径終端側に寄った位置では、引落部４６の長さ変化に伴って引落部４６のテーパの傾斜角が刻々と変わる場合でも、それぞれの外径測定器６５，６６の測定位置におけるガラス４１の外径変化は、引落部４６の中間部付近で測定する従来の場合と比較すると極めて小さな変化となる。
【００２７】
従って、いずれの外径測定器６５，６６においても、予め想定した定位置で、測定誤差が少なく、より正確な値として、ガラス４１の外径測定を行うことができ、その結果、第２の外径測定器６６の実測外径値のフィードバックによって第１の外径測定器６５用の第１の設定外径値をより高精度に算出制御することが可能になり、また、第１の外径測定器６５の実測外径値のフィードバックによってガラスの延伸速度をより高精度に制御することが可能になり、実測外径値に基づく延伸速度制御によって、延伸されたガラスの仕上がり外径の精度向上を図ることができる。
【００２８】
また、上記のように、各外径測定器６５，６６の測定誤差が少なくて済むため、制御装置６７による延伸速度制御に、タイミング遅れの補償等に有効なＰＩＤ制御を組み合わせることで、更に仕上がり外径の精度向上を図ることができる。
【００２９】
以上の作用効果を確認するため、本願発明者等は、上記実施形態に準じた実施例１〜実施例４でガラス４１の延伸を行って、製造した延伸体６３の外径を測定して、仕上がり外径の精度を調べた。
以下にその時の各実施例について詳述する。
【００３０】
（実施例１）
外径９０ｍｍのガラス４１を目標外径値３５ｍｍに延伸するため、上記延伸装置３０を使用して、以下の延伸を行った。
発熱体４３を２１００℃に昇温させた加熱炉４５に、外径９０ｍｍのガラス４１を投入し、当初、投入速度Ｖａを４．５ｍｍ／分に設定し、又、引き取り速度Ｖｃは３０ｍｍ／分に保持して延伸を開始し、各外径測定器６５，６６によって延伸途中のテーパ部の外径を実測し、第２の外径測定器６６による実測外径値と予め第２の外径測定器６６用に設定しておいた第２の設定外径値との差を制御装置６７にフィードバックして、実測外径値が第２の設定外径値Ｄ２となるような第１の設定外径値Ｄ１を算出させる。
算出した第１の設定外径値Ｄ１と第１の外径測定器６５の実測外径値との差を制御装置６７にフィードバックし、実測外径値が第１の設定外径値Ｄ１となるように投入速度Ｖａを制御することで、仕上がり外径の制御を行う。
初期値として、第２の設定外径値は３５．１ｍｍに、初期の第１の設定外径値（Ｄ１０）は３５．８ｍｍに設定し、各外径測定器６５，６６における実測外径値と設定外径値との差（Ｅ１（ｔ）＝第１の外径測定器の実測外径値−第１の設定外径値，Ｅ２（ｔ）＝第２の外径測定器の実測外径値−第２の設定外径値）を下記の（１）式で表される第１の設定外径値でＰＩＤ調節した後、下記の（２）式に従って、投入速度Ｖａを算出した。
【００３１】
【数１】

Figure 2004091297
【００３２】
ここで、（１）式のＤ１は、Ｔｆ毎に設定し、Ｔｆ＝１００ｓとした。
（２）式で、Ｖ０＝４．５ｍｍ／分とし、第２の外径測定器６６によって測定された外径が目標径に対して０．３ｍｍの差となった時点で、ＫＰ，ＴＩ，ＴＤの値を切り替え、外径差が０．３ｍｍ未満の時は、ＫＰ＝１／３０００、ＴＩ＝４０分、ＴＤ＝１０分とし、外径差が０．３ｍｍ以上となった時は、ＫＰ＝１／３０００、ＴＩ＝１０００分、ＴＤ＝１００分とした。
その結果、延伸外径は、図３の特性線ｆ１に示すように、３５±０．１ｍｍとなって、優れた仕上がり外径精度が得られた。
【００３３】
（実施例２）
実施例１と同じ構成、制御方式で、ＰＩＤ制御の制御パラメータ値を全長で、ＫＰ＝１／３０００、ＴＩ＝４０分、ＴＤ＝１０分とした。その結果、図４の特性線ｆ２に示すように、延伸中央部（図の横軸の１０００ｍｍ付近）の外径は３５±０．１ｍｍと良好であったが、延伸開始付近の外径が３５±０．５ｍｍとなった。
【００３４】
（実施例３）
実施例１と同じ構成、制御方式で、ＰＩＤ制御のパラメータ値を全長で、ＫＰ＝１／３０００、ＴＩ＝１０００分、ＴＤ＝１００分とした。その結果、図５の特性線ｆ３に示すように、延伸体の略全長に渡って、外径が３５±０．４ｍｍとなった。
以上の実施例１乃至実施例３の比較で判るように、ＰＩＤ制御のパラメータ値ＫＰ，ＴＩ，ＴＤは、縮径終端付近に配置した第２の外径測定器６６の実測外径値と目標外径との差に応じて、適宜に切り替えると、仕上がり外径の精度を向上できる。
【００３５】
（実施例４）
外径９０ｍｍのガラス４１を目標外径値３５ｍｍに延伸するため、上記延伸装置３０を使用して、以下の延伸を行った。
発熱体４３を２１００℃に昇温させた加熱炉４５に、外径９０ｍｍのガラス４１を投入し、当初、投入速度Ｖａを４．５ｍｍ／分に設定し、又、引き取り速度Ｖｃは当初は３０ｍｍ／分にして延伸を開始し、各外径測定器６５，６６によって延伸途中のテーパ部の外径を実測し、第２の外径測定器６６による実測外径値と予め第２の外径測定器６６用に設定しておいた第２の設定外径値との差を制御装置６７にフィードバックして、実測外径値が第２の設定外径値Ｄ２となるような第１の設定外径値Ｄ１を算出させる。
算出した第１の設定外径値Ｄ１と第１の外径測定器６５の実測外径値との差を制御装置６７にフィードバックし、実測外径値が第１の設定外径値Ｄ１となるように、投入速度Ｖａ及び引き取り速度Ｖｃを制御することで、仕上がり外径の制御を行う。
初期値として、第２の設定外径値は３５．１ｍｍに、初期の第１の設定外径値（Ｄ１０）は３５．８ｍｍに設定し、各外径測定器６５，６６における実測外径値と設定外径との差（Ｅ１（ｔ），Ｅ２（ｔ））を上記の（１）式で表される第１の設定外径値でＰＩＤ調節した後、下記の（３）式に従って、投入速度Ｖａを算出した。
引き取り機構５１による引き取り速度Ｖｃは、下記の（４）式に従って算出した。
【００３６】
【数２】
Figure 2004091297
【００３７】
ここで、（１）式のＤ１は、Ｔｆ毎に設定し、Ｔｆ＝１００ｓとした。
（３）式で、Ｖａ０＝４．５ｍｍ／分、Ｖｃ０＝３０ｍｍ／分とし、第２の外径測定器６６によって測定された外径が目標径に対して０．３ｍｍの差となった時点で、ＫＰ，ＴＩ，ＴＤ，Ｋｚの値を切り替えることとし、外径差が０．３ｍｍ未満の時は、ＫＰ＝１／３０００、ＴＩ＝４０分、ＴＤ＝１０分、Ｋｚ＝１／１２０００とし、外径差が０．３ｍｍ以上となった時は、ＫＰ＝１／３０００、ＴＩ＝１０００分、ＴＤ＝１００分、Ｋｚ＝１／１２０００とした。
その結果、延伸外径は、図６の特性線ｆ４に示すように、３５±０．０５ｍｍとなって、実施例１の場合よりも更に優れた仕上がり外径精度が得られた。
このことから、目標外径を得るための延伸速度制御は、投入速度Ｖａ及び引き取り速度Ｖｃの双方を、ＰＩＤ制御によって制御することが好ましい。
【００３８】
なお、上記の実施例１及び実施例４では、第２の外径測定器６６による実測外径値と目標外径の偏差を導入し、その偏差が０．３ｍｍの時点でＰＩＤ制御の各制御パラメータの切り替えを行ったが、種々の実験を行った結果、偏差が０．１〜１．０ｍｍの範囲にある切り替え点で制御パラメータを切り替えるようにすれば、高精度の外径制御を行うことで可能であることが判った。
【００３９】
また、偏差ではなく、偏差の傾きによっても、より早めに延伸中の外径の変化を予測することができ、偏差の傾きの大きさに基づいて、制御方式を切り替えるようにしてもよい。
このような制御によっても、外径の変化をより応答性良く検知することができる。
【００４０】
また、上記の各実施の形態では、制御方式はＰＩＤを用い、パラメータを切り替えるようにしたが、第１の外径測定器６５及び第２の外径測定器６６の少なくとも一方における実測外径値と目標外径との差に応じてＰＩＤ制御を用いることにより、偏差に応じた比例に加え、その微分量及び積分量に応じて制御を行うようにしても、高速で、且つ信頼性の高い制御が可能になる。
【００４１】
また、ＰＩＤ制御方式によるパラメータも、比例ゲイン、微分時間、積分時間があり、これらの設定値を２段階設定しておくようにし、実際に延伸を行っている場合の目標値の偏差又は傾きの大きさによって、どちらの設定値を使用するか選択して自動的に切り替えるようにしても良い。
その場合に、比例ゲインの設定範囲が１／１００００よりも小さ過ぎると制御性が期待できない。また、比例ゲインの設定範囲が１／６０よりも大き過ぎると、ハンチングを増幅して制御が安定しない。
従って、比例ゲインの設定範囲は、１／６０〜１／１００００の範囲にすると良い。
【００４２】
また、実測外径値と設定外径値（又は目標外径値）との差が大きい場合は、ＰＩＤ制御の際に、積分項に対して相対的に微分項での制御を強くする必要があり、積分時間を５０分以上とし、微分時間を５分以上とするとよい。
実測外径値と設定外径値（又は目標外径値）との差が小さい場合は、ＰＩＤ制御の際に、設定外径値（又は目標外径値）との差が大きい場合と比較して、積分項での制御を強くする必要があり、積分時間を５００分以下とし、微分時間を２００分以下とするとよい。
【００４３】
また、ＰＩＤ制御に限らず、もっと単純な比例制御にも応用することができる。この場合は、ＰＩＤ制御ではなく、ゲインを２段階設定しておくようにし、このゲインを切り替えるようにしてもよい。この切り替えは、ある時点の前後、例えば、目標値の近傍に到達した後は、制御をしないで、一定条件で延伸を行うような場合も含むものとする。
【００４４】
第１の外径測定器６５の位置は、第１の外径測定器６５による実測外径値が延伸されたガラスの目標外径値ｄの１００．５〜１２０％、好ましくは、１０１〜１０５％となる位置に設定すると共に、第２の外径測定器６６の位置を第２の外径測定器６６による実測外径値が目標外径値の１００〜１０５％、好ましくは、１００〜１０１％となる位置に設定するとよい。
更に、第１の外径測定器６５と第２の外径測定器６６との離間間隔Ｓを、それぞれの検出する実測外径値の差が目標外径値の０．５％以上となるように設定するとよい。
上記実施例の場合では、目標外径値３５ｍｍの１２０％となる位置は、引落部中央から縮径終端側へ引落部全長の約１／６離れた位置である。
【００４５】
なお、本発明において、第１の設定外径値は、時間間隔Ｔ毎に、算出する。その場合に、上記の各実施の形態では、第２の外径測定器６６で測定される実測外径値と予め設定された第２の設定外径値との偏差から算出するようにしたが、例えば、ｉ番目に算出する第１の設定外径値として、次の（５）式に示す移動平均値を用いるようにしてもよい。
移動平均値＝Σｂｉ・Ｒｉ−１／ｉ　　　　　　……（５）
上記の（５）式において、ｉは正の整数、ｂｉはｉ番目に第１の設定外径値を算出する際の補正係数、Ｒは実測外径値である。
【００４６】
【発明の効果】
本発明のガラスの延伸方法及び装置によれば、延伸させたガラスの仕上がり外径の精度向上を図ることができる。
また、上記のガラスの延伸方法及び装置では、各外径測定器の測定誤差が少なくて済むため、延伸速度制御に、タイミング遅れの補償等に有効なＰＩＤ制御を組み合わせることで、更に仕上がり外径の精度向上を図ることができる。
【図面の簡単な説明】
【図１】本発明に係るガラスの延伸装置の一実施の形態の概略構成図である。
【図２】図１に示したガラスの延伸装置においてガラスの投入速度の制御形態を示すブロック図である。
【図３】本発明の実施例１で製造したガラス棒の長さ方向への外径変化の測定図である。
【図４】本発明の実施例２で製造したガラス棒の長さ方向への外径変化の測定図である。
【図５】本発明の実施例３で製造したガラス棒の長さ方向への外径変化の測定図である。
【図６】本発明の実施例４で製造したガラス棒の長さ方向への外径変化の測定図である。
【図７】従来のガラスの延伸装置の概略構成図である。
【符号の説明】
４０　延伸装置
４１　ガラス母材
４３　発熱体
４５　加熱炉
４６　引落部
４７　上部チャック
４９　母材供給機構
５１　引き取り機構
５２　送り移動ボールネジ
５５　下部チャック
５７　引き取り移動ボールネジ
６５　第１の外径測定器
６６　第２の外径測定器
６７　制御装置[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method and an apparatus for drawing glass to be drawn into a heating furnace, and more particularly to an improvement for improving the outer diameter accuracy of drawn glass.
[0002]
[Prior art]
FIG. 7 shows a conventional example of a glass stretching apparatus for stretching a rod-shaped glass put into a heating furnace.
The glass stretching apparatus 20 shown here is that disclosed in Japanese Patent No. 3188404.
A heating furnace 5 for heating and softening the rod-shaped glass 1, a preform supply mechanism 4 for feeding the suspended glass 1 into the heating furnace 5 at a predetermined speed V1, and a glass end exiting from the heating furnace 5 at a predetermined speed. A take-off mechanism 6, a control device 9 and a control computer 10 for controlling the take-up speed V2 of the take-off mechanism 6, and an external position (C) of the heating furnace 5 for confirming the final outer diameter of the stretched body 2 to be produced. Outside diameter measuring device 11 provided in the heating furnace 5 and a drawn-down portion where the glass 1 in the heating furnace 5 is stretched and reduced in diameter in order to control a stretching speed (= drawing speed V2−feeding speed V1). Outer diameter measuring devices 7 and 8 are provided at two locations 1a (points A and B).
[0003]
The point B at the installation position of the outer diameter measuring device 8 is set near the end of the withdrawn portion 1a where the stretching and the diameter reduction are completed. Further, the point A at the installation position of the outer diameter measuring device 7 is a position where the stretching and the diameter reduction are performed most steeply, specifically, a substantially middle position of the length L of the withdrawn portion 1a (that is, the withdrawn portion 1a). (A position at a distance of L / 2 from the end of the line).
[0004]
The stretching method of the glass performed by the stretching apparatus 20 is such that the outer diameter of the glass 1 is measured at the two positions A and B during the stretching by the two outer diameter measuring devices 7 and 8 described above, and the glass is placed at the A position. The outer diameter set value of the outer diameter measuring device 7 was corrected based on the actually measured outer diameter value of the outer diameter measuring device 8 arranged at the position B, and the actually measured outer diameter value of the outer diameter measuring device 7 at the position A was corrected. By controlling the stretching speed by the control device 9 so that the outer diameter is set, the precision of the finished diameter is improved.
[0005]
On the other hand, Japanese Patent No. 3188404 proposes a technique incorporating PID control to control the stretching speed so that the outer diameter of the draw-down portion 1a at a point A becomes a preset value.
PID control, for example, when controlling the take-up speed in the stretching apparatus based on the difference between the measured outer diameter value and the target outer diameter value, is simply proportional to the difference between the actually measured outer diameter value and the target outer diameter value. Rather than controlling, control is performed in which the difference between the actually measured outer diameter value and the target outer diameter value is further added with the integral amount and the differential amount, and the C position where the finished diameter is measured and the A position where the outer diameter value is actually measured. This is effective for compensating for timing delay caused by the separation distance between them.
[0006]
[Problems to be solved by the invention]
By the way, in the above-mentioned stretching apparatus 20, the length L of the drawn-down portion 1a of the glass 1 in the heating furnace 5 varies depending on the individual difference of the glass 1, and of course, even in the same glass 1, It changes every moment with the progress of the stretching process by heating in the inside. The inclination angle of the taper changes with the change in the length L of the withdrawn portion 1a, and the intermediate position of the withdrawn portion 1a (the position at a distance of L / 2 from the end of the withdrawn portion 1a) also moves every moment.
In the vicinity of the middle position of the withdrawn portion 1a, a slight change in the position causes a large change in the outer diameter. Therefore, in order to accurately measure the outer diameter of the middle position of the withdrawn portion 1a, it is necessary to mount the outer diameter measuring device 7. An adjusting mechanism for displacing the position A in accordance with the change in the length of the pull-down portion 1a is required. However, it is difficult to make a hole for mounting the adjusting mechanism in the furnace core tube or the heat insulating material constituting the heating furnace 5. It is not realistic to displace the mounting position A of the outer diameter measuring device 7 following the change in the length of the pull-down portion 1a.
[0007]
Therefore, in the stretching apparatus 20 described in Japanese Patent No. 3188404, the error of the actually measured outer diameter value at the position A, which is the reference for adjusting the stretching speed, from the assumed outer diameter of the middle position of the drawn-down portion 1a increases. In addition, a control deviation occurs, and even if the above-described PID control is combined, there arises a problem that it is difficult to sufficiently improve the accuracy of the finished outer diameter of the stretched body 2.
[0008]
Accordingly, an object of the present invention is to solve the above-described problems, and even if the tapered shape of the drawn part changes due to the stretching of the glass in the heating furnace and the change in the length of the drawn part whose diameter has been reduced, it is possible to prevent the glass from being stretched during the drawing. It is an object of the present invention to provide a method and an apparatus for stretching glass which can measure the outer diameter of the glass as a more accurate value, with each of the outer diameter measuring devices arranged at the positions having little measurement error.
[0009]
[Means for Solving the Problems]
The above object of the present invention is a glass stretching method for stretching glass to be charged into a heating furnace as described in claim 1,
The glass is stretched, two outer diameter measuring devices to sequentially detect the outer diameter of the glass at a position closer to the diameter reduction end than a substantially middle portion of the length of the reduced diameter part,
A set outer diameter value of the other outer diameter measuring device is set based on the measurement result measured by one outer diameter measuring device, and the set outer diameter value and the set outer diameter value measured by the other outer diameter measuring device are measured. This is achieved by a method for stretching glass, wherein the stretching speed of the glass is controlled based on the difference from the measured outer diameter value.
[0010]
In addition, the object of the present invention is to provide a method of drawing glass according to claim 1, wherein the one outer diameter measuring device is arranged on a side closer to the reduced diameter end. The other outer diameter measuring device is treated as a first outer diameter measuring device, and the actually measured outer diameter value measured by the second outer diameter measuring device and the second outer diameter measurement are previously determined. This is achieved by a glass stretching method, wherein a first set outer diameter value of the first outer diameter measuring device is set based on a second set outer diameter value set dexterously.
[0011]
According to a third aspect of the present invention, in the glass stretching method according to the second aspect, the first set outer diameter value is measured by the second outer diameter measuring device. This is achieved by a method for stretching glass, characterized by using a deviation between the actually measured outer diameter value to be measured and the preset second set outer diameter value.
[0012]
In the method for stretching glass according to claim 2 or 3, the position of the first outer diameter measuring device is set to a position that is 100.5 to 120% of a target outer diameter value of the drawn glass. Preferably, the position of the second outer diameter measuring device is set to a position that is 100 to 105% of the target outer diameter value.
[0013]
Further, in the method for stretching glass according to claim 2 or 3, the distance between the first outer diameter measuring device and the second outer diameter measuring device, the difference between the actually measured outer diameter values to be detected respectively, It is preferable to set the value so as to be 0.5% or more of the target outer diameter value.
[0014]
In addition, the object of the present invention is, as described in claim 4, in the method for stretching glass according to claim 2 or 3, wherein the first set outer diameter value and the first outer diameter measuring device are used. This is achieved by a glass stretching method, wherein the stretching speed is PID-controlled based on a difference from a measured outer diameter value.
[0015]
Further, the object of the present invention is a glass stretching apparatus for stretching glass to be charged into a heating furnace, as described in claim 5,
At least two outer diameter measuring devices that are arranged in the middle of stretching of the glass and detect the outer diameter of the glass, and a measurement measured by one outer diameter measuring device of the two outer diameter measuring devices The set outer diameter value of the other outer diameter measuring device is set based on the result, and the stretching speed of the glass is set based on the difference between the set outer diameter value and the actually measured outer diameter value of the other outer diameter measuring device. Control device to control,
A glass stretching apparatus, wherein the two outer diameter measuring devices are provided at a position closer to the end of diameter reduction than a substantially middle portion of a portion where the glass is stretched and reduced in diameter. Is achieved by
[0016]
In the method and the apparatus for stretching glass having the above-described configuration, the outer diameter measuring devices are arranged at two positions during the stretching of the glass in the heating furnace. With respect to the length L of the drawn-down portion, it is set at a position closer to the diameter reducing end side than the intermediate portion.
In such a position closer to the end of the diameter reduction than the middle part of the withdrawn part, even if the inclination angle of the tapered part of the withdrawn part changes every moment as the length of the withdrawn part changes, each outer diameter measuring device The change in the outer diameter of the glass at the measurement position is a very small change as compared with the case where the measurement is performed near the middle part of the drawn part.
[0017]
Therefore, in any of the outer diameter measuring instruments, the measurement error is small at a predetermined position assumed in advance, and the outer diameter of the glass can be measured as a more accurate value. The feedback of the measured outer diameter value enables more accurate calculation and control of the set outer diameter value for the other outer diameter measuring device, and the stretching of the glass by the feedback of the measured outer diameter value of the other outer diameter measuring device. The speed can be controlled with higher precision, and the precision of the finished outer diameter of the drawn glass can be improved by controlling the stretching speed based on the measured outer diameter value.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a method and an apparatus for stretching glass according to the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an embodiment of a glass stretching apparatus according to the present invention.
The glass stretching apparatus 30 of this embodiment includes a heating furnace 45 for heating and softening the glass 41 by a heating element 43, an upper chuck 47 for holding a dummy bar 41 a integrated with an upper end of the glass 41, A glass supply mechanism 49 for feeding the glass 41 into the heating furnace 45 by lowering the chuck 47 toward the heating furnace 45 at a predetermined speed, and a take-up for pulling the dummy rod 41b at the lower end of the glass exiting the heating furnace 45 at a predetermined speed. And a mechanism 51.
[0019]
The glass supply mechanism 49 includes a feed moving ball screw 52 that supports the upper chuck 47 so as to be able to move up and down, and a motor 53 that drives the feed moving ball screw 52 to rotate. By controlling, the charging speed Va of the glass 41 can be set arbitrarily.
[0020]
The pickup mechanism 51 includes a lower chuck 55 for holding the dummy rod 41b, a pickup moving ball screw 57 for supporting the lower chuck 55 so as to be vertically movable, and a motor 59 for rotating the pickup movement ball screw 57. By controlling the rotation speed of the take-off moving ball screw 57 by the motor 59, the take-up speed Vc of the glass 41 can be set arbitrarily.
[0021]
The stretching apparatus 30 takes out the outer diameter of the glass 41 in advance by pulling the dummy rod 41b at an appropriate pulling speed by the pulling mechanism 51 in a state where the glass 41 put into the heating furnace 45 is heated and softened by the heating element 43. The stretched body 63 reduced in diameter to the set target outer diameter value is manufactured.
[0022]
A first outer diameter measuring device 65 for measuring the outer diameter of the glass 41 and a second outer diameter measuring device 66 are arranged at two places in the heating furnace 45 while the glass 41 is being stretched.
As shown in the drawing, when the total length of the drawn-down portion 46, which is a portion where the glass 41 is stretched and reduced in diameter, is set to L, the first and second outer diameter measuring devices 65 and 66 both use the drawn-down portion 46. Are fixedly mounted sequentially at a position closer to the diameter reducing end than a substantially middle portion of the length L (a position at a distance of L / 2 from the diameter reducing end of the withdrawn portion 46).
The position of the second outer diameter measuring device 66 is near the reduced diameter end of the pull-down portion 46, and the position of the first outer diameter measuring device 65 is a distance S from the second outer diameter measuring device 66 to the heating element 43 side. It is a position only separated.
[0023]
Further, in order to maintain the outer diameter (finished diameter) of the stretched body at the end of stretching in the heating furnace 45 to the above-mentioned target outer diameter value, the feeding speed Va of the glass 41 into the heating furnace 45 by the glass supply mechanism 49 and the take-off mechanism 51 Is controlled based on the actually measured outer diameter values detected by the respective outer diameter measuring devices 65 and 66, and the first and second set outer diameter values set in the respective outer diameter measuring devices 65 and 66. A control device 67 is provided.
[0024]
The control device 67 calculates the measured outer diameter value measured by the second outer diameter measuring device 66 disposed near the diameter reducing end and the second setting previously set for the second outer diameter measuring device 66. A first set outer diameter value for the first outer diameter measuring device 65 is set based on the outer diameter value, and the first set outer diameter value and the actually measured outer diameter of the first outer diameter measuring device 65 are set. The stretching speed of the glass 41 is controlled based on the difference from the value.
Note that the stretching speed is a value obtained by subtracting the charging speed Va by the glass supply mechanism 49 from the pulling speed by the pulling mechanism 51.
[0025]
As shown in FIG. 2, the control device 67 has a built-in PID adjuster 67a.
The control device 67 calculates a difference (E1 (t)) between the actually measured outer diameter value of the first outer diameter measuring device 65 and the first set outer diameter value, and the actual measured outer diameter value of the second outer diameter measuring device 66. After calculating the difference (E2 (t)) from the second set outer diameter value, the PID adjuster 67a controls (E1 (t)) and (E2 (t)) according to the integral amount and the derivative amount. PID control for adjusting (PID adjustment) by combining is performed, the charging speed Va of the glass 41 by the glass supply mechanism 49 is calculated, and the operation of the glass supply mechanism 49 is controlled so as to reach the calculated charging speed Va. Thus, the finished diameter of the stretched body 63 is maintained at the target outer diameter value.
[0026]
In the glass stretching method performed by the stretching apparatus 30 having the above-described configuration, the outer diameter measuring devices 65 and 66 are arranged at two positions during the stretching of the glass 41 in the heating furnace 45. Is set at a position closer to the diameter reduction end side than the intermediate part with respect to the length L of the drawn part 46 where the glass 41 in the heating furnace 45 is elongated and reduced in diameter.
In this manner, at the position closer to the diameter reducing end side than the middle part of the withdrawn part 46, even if the inclination angle of the taper of the withdrawn part 46 changes every moment as the length of the withdrawn part 46 changes, the outer diameter of each of the outer diameters decreases. The change in the outer diameter of the glass 41 at the measurement positions of the measuring devices 65 and 66 is extremely small as compared with the conventional case where the measurement is performed in the vicinity of the middle part of the drawn-down portion 46.
[0027]
Therefore, in any of the outer diameter measuring devices 65 and 66, the outer diameter of the glass 41 can be measured as a more accurate value at a predetermined position assumed in advance and as a more accurate value. The feedback of the measured outer diameter value of the outer diameter measuring device 66 makes it possible to calculate and control the first set outer diameter value for the first outer diameter measuring device 65 with higher accuracy. The feedback of the measured outer diameter value of the diameter measuring device 65 makes it possible to control the stretching speed of the glass with higher precision, and the stretching speed control based on the measured outer diameter value allows the accuracy of the finished outer diameter of the stretched glass to be improved. Improvement can be achieved.
[0028]
In addition, as described above, since the measurement error of each of the outer diameter measuring devices 65 and 66 can be reduced, the finishing speed can be further improved by combining the stretching speed control by the control device 67 with the PID control effective for compensating timing delay and the like. The accuracy of the outer diameter can be improved.
[0029]
In order to confirm the above effects, the present inventors performed stretching of the glass 41 in Examples 1 to 4 according to the above embodiment, and measured the outer diameter of the manufactured stretched body 63. The accuracy of the finished outer diameter was examined.
Hereinafter, each embodiment at that time will be described in detail.
[0030]
(Example 1)
In order to stretch the glass 41 having an outer diameter of 90 mm to a target outer diameter value of 35 mm, the following stretching was performed using the stretching apparatus 30 described above.
The glass 41 having an outer diameter of 90 mm is charged into the heating furnace 45 in which the heating element 43 is heated to 2100 ° C., and the charging speed Va is initially set to 4.5 mm / min, and the take-off speed Vc is 30 mm / min. And stretching is started, and the outer diameter of the tapered portion in the middle of the stretching is actually measured by each outer diameter measuring device 65, 66, and the actually measured outer diameter value by the second outer diameter measuring device 66 and the second outer diameter are previously determined. The difference from the second set outer diameter value set for the measuring device 66 is fed back to the control device 67, and the first setting such that the actually measured outer diameter value becomes the second set outer diameter value D2. The outer diameter value D1 is calculated.
The difference between the calculated first set outer diameter value D1 and the measured outer diameter value of the first outer diameter measuring device 65 is fed back to the control device 67, and the measured outer diameter value becomes the first set outer diameter value D1. By controlling the injection speed Va as described above, the finished outer diameter is controlled.
As an initial value, the second set outer diameter value is set to 35.1 mm, the initial first set outer diameter value (D10) is set to 35.8 mm, and the measured outer diameter in each of the outer diameter measuring devices 65 and 66 is set. Difference between the value and the set outer diameter value (E1 (t) = actual outer diameter value of first outer diameter measuring device−first set outer diameter value, E2 (t) = actual measurement of second outer diameter measuring device After adjusting the PID of the (outer diameter value−the second set outer diameter value) by the first set outer diameter value represented by the following equation (1), the charging speed Va was calculated according to the following equation (2). .
[0031]
(Equation 1)
Figure 2004091297
[0032]
Here, D1 in equation (1) is set for each Tf, and Tf = 100s.
In the equation (2), V 0 = 4.5 mm / min, and when the outer diameter measured by the second outer diameter measuring device 66 becomes a difference of 0.3 mm from the target diameter, K P , When the values of T I and T D are switched, and the outer diameter difference is less than 0.3 mm, K P = 1/3000, T I = 40 minutes, and T D = 10 minutes, and the outer diameter difference is 0.3 mm or more. , K P = 1/3000, T I = 1000 minutes, and T D = 100 minutes.
As a result, the stretched outer diameter was 35 ± 0.1 mm as shown by the characteristic line f1 in FIG. 3, and excellent finished outer diameter accuracy was obtained.
[0033]
(Example 2)
With the same configuration and control method as those of the first embodiment, the control parameter values of the PID control were set to K P = 1/3000, T I = 40 minutes, and T D = 10 minutes over the entire length. As a result, as shown by a characteristic line f2 in FIG. 4, the outer diameter at the central portion of the stretching (around 1000 mm on the horizontal axis in the drawing) was as good as 35 ± 0.1 mm, but the outer diameter near the start of stretching was 35 ± 0.1 mm. ± 0.5 mm.
[0034]
(Example 3)
With the same configuration and control method as in the first embodiment, the parameter values of the PID control were set to K P = 1/3000, T I = 1000 minutes, and T D = 100 minutes over the entire length. As a result, as shown by a characteristic line f3 in FIG. 5, the outer diameter was 35 ± 0.4 mm over substantially the entire length of the stretched body.
As can be seen from the comparison of the first to third embodiments, the parameter values K P , T I , and T D of the PID control are the measured outer diameters of the second outer diameter measuring device 66 arranged near the diameter reduction end. By appropriately switching according to the difference between the value and the target outer diameter, the accuracy of the finished outer diameter can be improved.
[0035]
(Example 4)
In order to stretch the glass 41 having an outer diameter of 90 mm to a target outer diameter value of 35 mm, the following stretching was performed using the stretching apparatus 30 described above.
The glass 41 having an outer diameter of 90 mm is charged into the heating furnace 45 in which the heating element 43 is heated to 2100 ° C., and the charging speed Va is initially set to 4.5 mm / min, and the take-up speed Vc is initially 30 mm. / Min. And start the stretching. The outer diameter of the tapered portion in the middle of the stretching is actually measured by the outer diameter measuring devices 65 and 66, and the actually measured outer diameter value by the second outer diameter measuring device 66 and the second outer diameter are previously determined. The difference from the second set outer diameter value set for the measuring device 66 is fed back to the control device 67, and the first setting such that the actually measured outer diameter value becomes the second set outer diameter value D2. The outer diameter value D1 is calculated.
The difference between the calculated first set outer diameter value D1 and the measured outer diameter value of the first outer diameter measuring device 65 is fed back to the control device 67, and the measured outer diameter value becomes the first set outer diameter value D1. As described above, by controlling the input speed Va and the take-off speed Vc, the finished outer diameter is controlled.
As an initial value, the second set outer diameter value is set to 35.1 mm, the initial first set outer diameter value (D10) is set to 35.8 mm, and the measured outer diameter in each of the outer diameter measuring devices 65 and 66 is set. After the PID adjustment of the difference between the value and the set outer diameter (E1 (t), E2 (t)) with the first set outer diameter value represented by the above equation (1), the following equation (3) is used. And the charging speed Va were calculated.
The pick-up speed Vc by the pick-up mechanism 51 was calculated according to the following equation (4).
[0036]
(Equation 2)
Figure 2004091297
[0037]
Here, D1 in equation (1) is set for each Tf, and Tf = 100s.
In the equation (3), V a0 = 4.5 mm / min, V c0 = 30 mm / min, and the outer diameter measured by the second outer diameter measuring device 66 is a difference of 0.3 mm from the target diameter. At this point, the values of K P , T I , T D , and Kz are switched. When the outer diameter difference is less than 0.3 mm, K P = 1/3000, T I = 40 minutes, and T D = 10 And Kz = 1/12000, and when the difference in outer diameter was 0.3 mm or more, K P = 1/3000, T I = 1000 minutes, T D = 100 minutes, and Kz = 1/12000.
As a result, the stretched outer diameter was 35 ± 0.05 mm as shown by the characteristic line f4 in FIG. 6, and a more excellent finished outer diameter accuracy than in the case of Example 1 was obtained.
For this reason, in the stretching speed control for obtaining the target outer diameter, it is preferable to control both the charging speed Va and the take-up speed Vc by PID control.
[0038]
In the first and fourth embodiments, the deviation between the measured outer diameter value by the second outer diameter measuring device 66 and the target outer diameter is introduced. When the deviation is 0.3 mm, each control of the PID control is performed. Although the parameters were switched, as a result of various experiments, if the control parameters were switched at a switching point where the deviation was in the range of 0.1 to 1.0 mm, highly accurate outer diameter control could be performed. It turned out to be possible.
[0039]
Further, the change in the outer diameter during stretching can be predicted earlier not only by the deviation but also by the gradient of the deviation, and the control method may be switched based on the magnitude of the gradient of the deviation.
Even with such control, a change in the outer diameter can be detected with higher responsiveness.
[0040]
Further, in each of the above embodiments, the control method uses the PID and switches the parameters. However, the actual measured outer diameter value in at least one of the first outer diameter measuring device 65 and the second outer diameter measuring device 66 is used. By using the PID control in accordance with the difference between the target and the target outer diameter, even if the control is performed in accordance with the differential amount and the integral amount in addition to the proportionality in accordance with the deviation, high speed and high reliability can be achieved. Control becomes possible.
[0041]
The parameters according to the PID control method also include a proportional gain, a differentiation time, and an integration time, and these setting values are set in two stages so that a deviation or a slope of a target value or a slope in a case where stretching is actually performed is set. Depending on the size, which setting value to use may be selected and automatically switched.
In this case, if the setting range of the proportional gain is smaller than 1/10000, controllability cannot be expected. If the setting range of the proportional gain is too large than 1/60, hunting is amplified and control is not stabilized.
Therefore, the setting range of the proportional gain is preferably set in the range of 1/60 to 1/10000.
[0042]
If the difference between the measured outer diameter value and the set outer diameter value (or the target outer diameter value) is large, it is necessary to increase the control of the differential term relative to the integral term during PID control. Yes, the integration time should be 50 minutes or more, and the differentiation time should be 5 minutes or more.
When the difference between the measured outer diameter value and the set outer diameter value (or target outer diameter value) is small, the PID control is compared with the case where the difference between the set outer diameter value (or target outer diameter value) is larger. Therefore, it is necessary to strengthen the control of the integral term, and it is preferable to set the integral time to 500 minutes or less and the differential time to 200 minutes or less.
[0043]
Further, the present invention can be applied not only to the PID control but also to a simpler proportional control. In this case, instead of the PID control, the gain may be set in two stages, and the gain may be switched. This switching includes a case where stretching is performed under a certain condition without performing control before and after a certain time point, for example, after reaching a target value.
[0044]
The position of the first outer diameter measuring device 65 is 100.5 to 120%, preferably 101 to 105% of the target outer diameter value d of the stretched glass whose actual outer diameter value measured by the first outer diameter measuring device 65 is stretched. %, And the position of the second outer diameter measuring device 66 is set to 100 to 105%, preferably 100 to 101%, of the target outer diameter value measured by the second outer diameter measuring device 66. %.
Further, the distance S between the first outer diameter measuring device 65 and the second outer diameter measuring device 66 is set so that the difference between the actually measured outer diameter values is 0.5% or more of the target outer diameter value. It is good to set to.
In the case of the above embodiment, the position at which the target outer diameter value becomes 120% of the target outer diameter value is about 1/6 of the entire length of the drawn part from the center of the drawn part toward the end of the diameter reduction.
[0045]
In the present invention, the first set outer diameter value is calculated for each time interval T. In that case, in each of the above embodiments, the calculation is performed from the deviation between the actually measured outer diameter value measured by the second outer diameter measuring device 66 and the second set outer diameter value set in advance. For example, a moving average value represented by the following equation (5) may be used as the first set outer diameter value calculated at the i-th time.
Moving average value = Σbi · R i−1 / i (5)
In the above equation (5), i is a positive integer, bi is a correction coefficient for calculating the i-th first set outer diameter value, and R is an actually measured outer diameter value.
[0046]
【The invention's effect】
According to the method and apparatus for stretching glass of the present invention, it is possible to improve the accuracy of the finished outer diameter of the stretched glass.
In addition, in the above-described glass stretching method and apparatus, since the measurement error of each outer diameter measuring device can be reduced, by combining the stretching speed control with PID control effective for compensating timing delay, etc., the finished outer diameter can be further improved. Accuracy can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment of a glass stretching apparatus according to the present invention.
FIG. 2 is a block diagram showing a control mode of a glass charging speed in the glass stretching apparatus shown in FIG.
FIG. 3 is a measurement diagram of a change in outer diameter in a length direction of a glass rod manufactured in Example 1 of the present invention.
FIG. 4 is a measurement diagram of a change in outer diameter in a length direction of a glass rod manufactured in Example 2 of the present invention.
FIG. 5 is a measurement diagram of a change in outer diameter in a length direction of a glass rod manufactured in Example 3 of the present invention.
FIG. 6 is a measurement diagram of a change in outer diameter in a length direction of a glass rod manufactured in Example 4 of the present invention.
FIG. 7 is a schematic configuration diagram of a conventional glass stretching apparatus.
[Explanation of symbols]
40 Stretching device 41 Glass base material 43 Heating element 45 Heating furnace 46 Pull-down part 47 Upper chuck 49 Base material supply mechanism 51 Pick-up mechanism 52 Feed moving ball screw 55 Lower chuck 57 Pick-up moving ball screw 65 First outer diameter measuring device 66 Second Outer diameter measuring device 67 Control device

Claims (5)

加熱炉内に投入されるガラスを延伸するガラスの延伸方法であって、
前記ガラスが延伸、縮径している部分の長さの略中間部よりも縮径終端側の位置にガラスの外径を検出する２台の外径測定器を順次配置し、
一方の外径測定器で測定された測定結果に基づいて他方の外径測定器の設定外径値を設定すると共に、この設定した設定外径値と前記他方の外径測定器で測定される実測外径値との差に基づいて前記ガラスの延伸速度を制御することを特徴とするガラスの延伸方法。A method for stretching glass that stretches glass to be charged into a heating furnace,
The glass is stretched, two outer diameter measuring instruments for sequentially detecting the outer diameter of the glass at a position closer to the end of the diameter reduction than a substantially middle portion of the length of the part where the diameter is reduced are sequentially arranged,
A set outer diameter value of the other outer diameter measuring device is set based on the measurement result measured by one outer diameter measuring device, and the set outer diameter value and the set outer diameter value are measured by the other outer diameter measuring device. A method for stretching glass, comprising controlling a stretching speed of the glass based on a difference from an actually measured outer diameter value. 前記一方の外径測定器を前記縮径終端により近い側に配置した第２の外径測定器として扱い、前記他方の外径測定器を第１の外径測定器として扱い、前記第２の外径測定器で測定される実測外径値と予め第２の外径測定器用に設定された第２の設定外径値とに基づいて前記第１の外径測定器の第１の設定外径値を設定することを特徴とする請求項１記載のガラスの延伸方法。Treating the one outer diameter measuring instrument as a second outer diameter measuring instrument arranged closer to the reduced diameter end, treating the other outer diameter measuring instrument as a first outer diameter measuring instrument, The first outside diameter of the first outside diameter measuring device is set based on an actual outside diameter value measured by the outside diameter measuring device and a second set outside diameter value previously set for the second outside diameter measuring device. The method for drawing glass according to claim 1, wherein a diameter value is set. 前記第１の設定外径値として、前記第２の外径測定器で測定される実測外径値と予め設定された前記第２の設定外径値との偏差を用いることを特徴とする請求項２記載のガラスの延伸方法。The method according to claim 1, wherein a deviation between an actually measured outer diameter value measured by the second outer diameter measuring device and a preset second set outer diameter value is used as the first set outer diameter value. Item 3. The method for stretching glass according to Item 2. 前記第１の設定外径値と前記第１の外径測定器で測定される実測外径値との差に基づいて前記延伸速度をＰＩＤ制御することを特徴とする請求項２又は３に記載のガラスの延伸方法。The PID control of the stretching speed is performed based on a difference between the first set outer diameter value and an actually measured outer diameter value measured by the first outer diameter measuring device. Glass stretching method. 加熱炉内に投入されるガラスを延伸するガラスの延伸装置であって、
少なくとも前記ガラスの延伸途中に配置されて、前記ガラスの外径を検出する２台の外径測定器と、これら２台の外径測定器の内、一方の外径測定器で測定された測定結果に基づいて他方の外径測定器の設定外径値を設定すると共に、この設定外径値と前記他方の外径測定器の実測外径値との差に基づいて前記ガラスの延伸速度を制御する制御装置とを備え、
前記２台の外径測定器は、前記ガラスが延伸、縮径している部分の長さの略中間部よりも縮径終端側の位置に装備されていることを特徴とするガラスの延伸装置。A glass stretching apparatus for stretching glass to be charged into a heating furnace,
At least two outer diameter measuring instruments that are arranged in the middle of the stretching of the glass and detect the outer diameter of the glass, and a measurement measured by one of the two outer diameter measuring instruments. The set outer diameter value of the other outer diameter measuring device is set based on the result, and the stretching speed of the glass is set based on the difference between the set outer diameter value and the actually measured outer diameter value of the other outer diameter measuring device. Control device to control,
A glass stretching apparatus, wherein the two outer diameter measuring devices are provided at a position closer to the end of diameter reduction than a substantially middle portion of a portion where the glass is stretched and reduced in diameter. .
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JP2011037692A (en) * 2009-08-18 2011-02-24 Sumitomo Electric Ind Ltd Method for drawing glass preform

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011037692A (en) * 2009-08-18 2011-02-24 Sumitomo Electric Ind Ltd Method for drawing glass preform

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