JP2004314126A

JP2004314126A - Method of detecting abnormality in temperature sensor for predicting constrainable breakout

Info

Publication number: JP2004314126A
Application number: JP2003111610A
Authority: JP
Inventors: Jun Sakai; 純酒井; Yasushi Abe; 靖阿部; Eiji Tawara; 栄司俵
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2003-01-31
Filing date: 2003-04-16
Publication date: 2004-11-11
Anticipated expiration: 2023-04-16
Also published as: JP4214818B2

Abstract

<P>PROBLEM TO BE SOLVED: To correctly detect the slowdown in the change of output to the change in the temperature of thermocouples on-line. <P>SOLUTION: In the method, at the time when the change of the measured temperature value on operation by a plurality of thermocouples fitted to a mold in continuous casting equipment satisfies prescribed conditions, it is decided as abnormality and constrainable breakout is predicted based on the decided result as for the abnormality, the abnormal slowdown of the change in output to the change in the temperature of the thermocouples is detected. In this case, the confirmation frequencies N<SB>1</SB>and N<SB>2</SB>of the abnormal decision as for the change of the measured temperature value in the two thermocouples arranged at different positions are compared, further, at the time when the higher confirmation frequency N<SB>1</SB>is the prescribed one n or higher, and also, the ratio N<SB>1</SB>/N<SB>2</SB>obtained by dividing the higher confirmation frequency N<SB>1</SB>by the lower confirmation frequency N<SB>2</SB>is a prescribed value H or higher, the fact that the change in output to the change in the temperature of the thermocouples in the lower confirmation frequency N<SB>2</SB>is abnormally slowed down is detected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、連続鋳造設備の拘束性ブレークアウトの予知に用いられる温度センサの異常を検知する方法に関する。
【０００２】
【従来の技術】
拘束性ブレークアウトとは、連続鋳造時に例えばモールドパウダーの鋳型・鋳片間への流入不良による潤滑不良等が原因で鋳型・鋳片間に焼付きが発生し、鋳片を下方に引き抜いた時に焼付部分の凝固シェルが破断してこの破断部が鋳型の下端から露出したところで鋳型内の溶鋼が外部に漏れ出すことをいう。
【０００３】
連続鋳造時にこの拘束性ブレークアウトが発生すると、鋳造中断や設備損傷を引き起して生産性を低下させることになるため、従来においては、鋳型外面に複数の熱電対（温度センサ）を埋設して該熱電対による測温値の変化の異常を検出し、該検出結果に基づいて拘束性ブレークアウトの発生を推定して警報等を発し、鋳込速度を遅くする等の対策を施している。
【０００４】
ところで、熱電対の劣化、熱電対のケーブルの異常、熱電対と鋳型外面（銅板）との接触不良、熱電対の浸水異常等が生じると、実際の鋳型銅板の温度変化に対して熱電対の出力変化が鈍化して、即ち、出力変化が正常な熱電対よりも小さくなって時間遅れ等が生じ、熱電対による測温値変化の異常検出の精度が低下して拘束性ブレークアウトの予知の信頼性が損なわれることになる。
【０００５】
この場合、熱電対単体の検査を行って正常、異常を判定する方法が提案されているが（例えば特許文献１参照）、これでは、熱電対を鋳型外面に取り付けた状態での該熱電対の劣化、熱電対のケーブルの異常、熱電対と鋳型外面（銅板）との接触不良、熱電対の浸水異常等を検査することができないことから、従来においては、鋳型外面に熱電対を取り付けた状態で該熱電対を蒸気やバーナで加熱してその出力変化により熱電対の正常、異常を判定するようにしたものが提案されている（例えば特許文献２参照）。
【０００６】
【特許文献１】
特開平６−１３７９５６号公報
【特許文献２】
特開平８−１５９８８３号公報
【０００７】
【発明が解決しようとする課題】
しかしながら、特許文献２に記載のように蒸気やバーナで熱電対を加熱しても実際の溶鋼熱で鋳型を介して熱電対を衝撃的に加熱するものではないため、正常な熱電対と異常な熱電対との出力変化に有意差が得られにくく、仮に熱電対の異常を判定できたとしても、連続鋳造を継続していくうちに徐々に劣化したり冷却水等が浸水して出力変化が鈍化していく熱電対を検知することはできないという不都合がある。
【０００８】
本発明はこのような不都合を解消するためになされたものであり、第１の目的は、温度センサの温度変化に対する出力変化の鈍化をオンラインで正確に検知することができる拘束性ブレークアウト予知用温度センサの異常検知方法を提供することにある。
また、本発明の第２の目的は、温度センサの浸水異常をオンラインで正確に、且つ迅速に検知することができる拘束性ブレークアウト予知用温度センサの異常検知方法を提供することにある。
更に、本発明の第３の目的は、温度センサの温度変化に対する出力変化の鈍化をオンラインで正確に、且つ鋳造初期に検知することができる拘束性ブレークアウト予知用温度センサの異常検知方法を提供することにある。
【０００９】
【課題を解決するための手段】
上記第１の目的を達成するために、請求項１に係る発明は、連続鋳造設備の鋳型に取り付けられた複数の温度センサによる操業時の測温値の変化が所定の条件を満たしたときに異常と判定し、該異常判定結果に基づいて拘束性ブレークアウトを予知するに際して、前記温度センサの温度変化に対する測温値の変化の異常鈍化を検知する拘束性ブレークアウト予知用温度センサの異常検知方法であって、
異なる位置に配置された二つの前記温度センサにおける測温値の変化の前記異常判定の成立回数を比較すると共に、前記成立回数が多い方の前記温度センサの該成立回数が所定の回数以上とされ、且つ前記成立回数が多い方の前記温度センサの該成立回数と前記成立回数が少ない方の前記温度センサの該成立回数との関係が所定の条件を満たしたときに、前記成立回数が少ない方の前記温度センサの温度変化に対する測温値の変化が異常鈍化したことを検知することを特徴とする。
【００１０】
上記第２の目的を達成するために、請求項２に係る発明は、連続鋳造設備の鋳型に取り付けられた複数の温度センサによる操業時の測温値の変化が所定の条件を満たしたときに異常と判定し、該異常判定結果に基づいて拘束性ブレークアウトを予知するに際して、前記温度センサの浸水異常を検知する拘束性ブレークアウト予知用温度センサの異常検知方法であって、
所定の周期でサンプリングした前記温度センサの測温値の平均温度を演算すると共に、前記測温値の平均偏差を演算し、前記平均温度が所定の温度範囲内とされ、且つ前記平均偏差が所定の値以下のときに、前記温度センサの浸水異常であることを検知することを特徴とする。
【００１１】
上記第３の目的を達成するために、請求項３に係る発明は、連続鋳造設備の鋳型に取り付けられた複数の温度センサによる操業時の測温値の変化が所定の条件を満たしたときに異常と判定し、該異常判定結果に基づいて拘束性ブレークアウトを予知するに際して、前記温度センサの温度変化に対する出力変化の異常鈍化を検知する拘束性ブレークアウト予知用温度センサの異常検知方法であって、
前記温度センサの鋳造初期の測温値の温度変化率を算出し、前記温度変化率が所定の値以下の場合に、該温度センサの温度変化に対する出力変化が鈍化したことを検知することを特徴とする。
請求項４に係る発明は、請求項３において、前記温度センサの鋳造初期の測温値の最高到達温度が所定の値以下の場合に、該温度センサの温度変化に対する出力変化が鈍化したことを検知することを特徴とする。
【００１２】
【発明の実施の形態】
以下、本発明の実施の形態を図を参照して説明する。図１は本発明の第１の態様の実施の形態の一例である拘束性ブレークアウト予知用温度センサの異常検知方法を説明するための説明図、図２は熱電対出力（測温値）変化鈍化検知手段の作動を説明するためのフローチャート図、図３は本発明の第２の態様の実施の形態の一例である拘束性ブレークアウト予知用温度センサの異常検知方法を説明するための説明図、図４は熱電対の取付構造を説明するための断面図、図５は浸水検知用コントローラの作動を説明するためのフローチャート図、図６は正常な熱電対及び浸水異常の熱電対における測温値と時間と鋳込み速度との関係を示すグラフ図、図７は本発明の第３の態様の実施の形態の一例である拘束性ブレークアウト予知用温度センサの異常検知方法を説明するための説明図、図８は鈍化検知用コントローラの作動を説明するためのフローチャート図、図９は正常な熱電対及び鈍化異常の熱電対における鋳造初期の測温値と連続鋳造時の経過時間との関係を示すグラフ図である。
【００１３】
まず、本発明の第１の態様の実施の形態から説明すると、図１において符号１は連続鋳造用鋳型、Ｔ１０１〜Ｔ１３２はこの鋳型１の外面（銅板）に周方向に沿って複数箇所埋設された熱電対（温度センサ）であり、各熱電対Ｔ１０１〜Ｔ１３２による測温値Ｔはコントローラ３によって所定の周期でサンプリングされて所定のプログラムによる処理が実行される。
コントローラ３は、Ｆ（σ）演算手段４、測温値変化異常判定手段５、拘束性ブレークアウト判定手段６及び熱電対出力（測温値）変化鈍化検知手段７を備える。
【００１４】
測温値変化異常判定手段５は、個々の熱電対Ｔ１０１〜Ｔ１３２毎に操業時の測温値の変化が異常であるか否かを判定するものであり、次式（１）及び（２）の両方の条件を満たしたときに測温値の変化が異常であると判定し、該異常判定結果に基づいて拘束性ブレークアウト判定手段６は公知の判定ロジックを用いて拘束性ブレークアウトか否かを判定し、拘束性ブレークアウトと判定した場合は警報をモニタ画面等に表示したり、警報音を発生させる信号を出力し、この警報を認識した時点で鋳込速度を遅くする等の対策を施す。
【００１５】
Ｔ_ｉ≧Ｆ（σ） …（１）
Ｔ_ｉ−Ｔ_ｉ−１≧ΔＴ …（２）
但し、Ｆ（σ）：Ｆ（σ）演算手段４によって与えられる値でＴ_ｉに対するしきい値（変動値）
Ｔ_ｉ：最新測温値
Ｔ_ｉ−１：前回測温値
ΔＴ：しきい値（固定値：熱電対の最小測温単位の２〜３倍程度）Ｆ（σ）演算手段４は、最新測温値Ｔ_ｉ以前の過去の一定期間（例えば１０点）の測温値の標準偏差σを変数とした関数Ｆ（σ）を各熱電対Ｔ１０１〜Ｔ１３２毎且つサンプリング周期毎に算出するものであり、次式（３）により算出される。
【００１６】
Ｆ（σ）＝Ｔ（ａｖｇ）＋ｋσ …（３）
但し、Ｔ（ａｖｇ）：最新測温値Ｔ_ｉ以前の過去の一定期間（例えば１０点）の測温値の平均値
σ ：最新測温値Ｔ_ｉ以前の過去の一定期間（例えば１０点）の測温値の標準偏差
ｋ：測温値とブレークアウト痕等の関係から経験的に定まる定数で、この実施の形態ではｋ＝３に設定する。
【００１７】
各熱電対Ｔ１０１〜Ｔ１３２について、各測温値を基にＦ（σ）演算手段４によって演算されたＦ（σ）は熱電対Ｔ１０１〜Ｔ１３２の応答性のばらつきに応じて変更され、且つサンプリング周期毎に更新されて鋳込状況に応じて変動する。
熱電対出力変化鈍化検知手段７は、異なる位置に配置された二つの熱電対による測温値変化の前記測温値変化異常判定手段５による異常判定の成立回数を比較すると共に、成立回数が多い方の熱電対の該成立回数が所定の回数ｎ以上とされ、且つ成立回数が多い方の熱電対の該成立回数を成立回数が少ない方の熱電対の該成立回数で除した比率が所定値Ｈ以上のときに、成立回数が少ない方の熱電対の温度変化に対する出力変化が、熱電対の劣化、熱電対のケーブルの異常、熱電対と鋳型外面（銅板）との接触不良、熱電対の浸水異常等により鈍化したことを検知する。
【００１８】
異なる位置に配置された二つの熱電対の組み合わせに特に制限はないが、もっとも好ましい熱電対の組合せは、鋳型１の短辺または長辺方向に向かい合う一対である。図１では短辺方向に向かい合う熱電対Ｔ１０３と熱電対Ｔ１２８の一対、長辺方向に向かい合う熱電対Ｔ１３１と熱電対Ｔ１１６の一対が例示できる。
鋳型１の短辺または長辺方向に向かい合う一対の熱電対は、熱電対に異常のない場合、同様な測温値の変化を示す。そのため、一方の熱電対の異常を敏感に検出できる。言うまでもなく、別の一対、例えば隣接する一対を選択することができる。また、一つの熱電対の鈍化を検出するために、該熱電対と短辺または長辺方向に向かい合う熱電対からなる一対を選択して検知に供すると同時に、該熱電対と隣接する熱電対からなる一対を選択して検知に供してもよい。
【００１９】
次に、熱電対出力変化鈍化検知手段７の具体的作動を図２を参照して説明する。なお、ここでは、鋳型１の短辺方向に互いに向かい合う一対の熱電対Ｔ１０３、Ｔ１２８を例に採って説明する。
まず、ステップＳ１では、熱電対Ｔ１０３の測温値変化の前記測温値変化異常判定手段５による異常判定の成立回数Ｎ_１と熱電対Ｔ１２８の測温値変化の前記測温値変化異常判定手段５による異常判定の成立回数Ｎ_２とを比較して、Ｎ_１＞Ｎ_２のときはステップＳ２へ移行し、Ｎ_１＞Ｎ_２でないときはステップＳ５に移行する。
【００２０】
ステップＳ２では、熱電対Ｔ１０３における前記異常判定の成立回数Ｎ_１が予め実験や経験等で定められた所定回数ｎ以上であるか否かを判断し、Ｎ_１≧ｎであればステップＳ３に移行する。ステップＳ３では、熱電対Ｔ１０３における前記異常判定の成立回数Ｎ_１を熱電対Ｔ１２８における前記異常判定の成立回数Ｎ_２で除した比率Ｎ_１／Ｎ_２が予め実験や経験等で定められた所定の比率Ｈ以上であるか否かを判断し、Ｎ_１／Ｎ_２≧Ｈであれば、熱電対Ｔ１２８の温度変化に対する出力変化が、熱電対の劣化、熱電対のケーブルの異常、熱電対と鋳型外面（銅板）との接触不良、熱電対の浸水異常等により鈍化したことを検知し（ステップＳ４）、オペレータ等に警報等を発するか、或いは熱電対Ｔ１２８を不使用状態にする信号を出力する。
【００２１】
一方、ステップＳ５では、熱電対Ｔ１０３の測温値変化の前記測温値変化異常判定手段５による異常判定の成立回数Ｎ_１と熱電対Ｔ１２８の測温値変化の前記測温値変化異常判定手段５による異常判定の成立回数Ｎ_２とを比較して、Ｎ_２＞Ｎ_１のときはステップＳ６へ移行する。
ステップＳ６では、熱電対Ｔ１２８における前記異常判定の成立回数Ｎ_２が予め実験や経験等で定められた所定回数ｎ以上であるか否かを判断し、Ｎ_２≧ｎであればステップＳ７に移行する。ステップＳ７では、熱電対Ｔ１２８における前記異常判定の成立回数Ｎ_２を熱電対Ｔ１０３における前記異常判定の成立回数Ｎ_１で除した比率Ｎ_２／Ｎ_１が予め実験や経験等で定められた所定の比率Ｈ以上であるか否かを判断し、Ｎ_２／Ｎ_１≧Ｈであれば、熱電対Ｔ１０３の温度変化に対する出力変化が、熱電対の劣化、熱電対のケーブルの異常、熱電対と鋳型外面（銅板）との接触不良、熱電対の浸水異常等により鈍化したことを検知し（ステップＳ８）、オペレータ等に対して警報等を発するか、或いは熱電対Ｔ１０３を不使用状態にする信号を出力する。
【００２２】
上記の説明から明らかなように、この実施の形態では、操業時の実際の溶鋼熱による熱電対の測温値の変化に基づく異常判定の成立回数を用いて前記熱電対の温度変化に対する出力変化の鈍化を検知するようにしているので、熱電対の劣化、熱電対のケーブルの異常、熱電対と鋳型外面（銅板）との接触不良、熱電対の浸水異常等による熱電対の出力変化の鈍化をオンラインで正確に検知することができる。
【００２３】
なお、上記第１の態様の実施の形態では、鋳型１の外面（銅板）に周方向に沿って複数の熱電対を一段取り付けた場合を例に採ったが、これに限定されず、上下二段或いは上下三段以上に熱電対を取り付けた場合にも本発明を適用してもよい。
また、上記第１の態様の実施の形態では、測温値変化異常判定手段５による個々の熱電対Ｔ１０１〜Ｔ１３２の測温値変化の異常判定を上式（１）及び（２）の両方の条件を満たしたときとしているが、これに限定されず、他の公知の判定ロジックを用いて各熱電対Ｔ１０１〜Ｔ１３２の測温値変化の異常を判定するようにしてもよい。
【００２４】
更に、上記第１の態様の実施の形態では、成立回数が多い方の熱電対の該成立回数を成立回数が少ない方の熱電対の該成立回数で除した比率が所定値Ｈ以上のときに、成立回数が少ない方の熱電対の温度変化に対する出力変化が鈍化したことを検知するようにしているが、これに代えて、一定期間（例えば操業状況に応じて１日、２日、１週間等）における成立回数が多い方の熱電対の該成立回数と成立回数が少ない方の熱電対の該成立回数との差を求めて、この差が一定回数以上になった場合に、成立回数が少ない方の熱電対の温度変化に対する出力変化が鈍化したことを検知するようにしてもよい。
【００２５】
次に、図３〜図６を参照して、本発明の第２の態様の実施の形態の一例である拘束性ブレークアウト予知用温度センサの異常検知方法を説明する。なお、上記第１の態様の実施の形態と重複する部分については、各図に同一符号を付して説明する。
図３において符号１は連続鋳造用鋳型、Ｔ１０１〜Ｔ１３２はこの鋳型１の外面（銅板）に周方向に沿って複数箇所埋設された熱電対（温度センサ）であり、各熱電対Ｔ１０１〜Ｔ１３２による測温値は浸水検知用コントローラ３１によって例えば数時間の浸水ロジック周期毎に所定の周期でサンプリングされて所定のプログラムによる処理が実行される。
【００２６】
熱電対Ｔ１０１〜Ｔ１３２はいずれも同一構造であるため、熱電対Ｔ１０１について説明すると、熱電対Ｔ１０１は、図４に示すように、鋳型１の銅板とバックアップフレーム（水箱）２０とを固定しているスタッドボルト２１の軸芯を中空化し、その穴に通されてスプリング２２により鋳型１の外面に押し付られた状態で着脱自在に取り付けられており、中空のスタッドボルト２１内に水が浸入することで熱電対が浸水状態となり出力変化に異常をきたす（水の沸点近傍の温度以上を測定できなくなる）。なお、図４において符号２３はスタッドボルト２１の先端と鋳型１の外面との間に介装されたＯリング、２４は冷却水溝である。
【００２７】
コントローラ３１は、平均温度度演算手段４１、平均偏差演算手段５１及び浸水異常検知手段６１を備える。
平均温度演算手段４１は、各熱電対Ｔ１０１〜Ｔ１３２毎に測温値のサンプリングデータの合計をサンプリングデータ数で除して平均温度Ｔｓ（ａｖｇ）を算出する。
平均偏差演算手段５１は、各熱電対Ｔ１０１〜Ｔ１３２毎に全ての測温値のサンプリングデータについて、該サンプリングデータと前記平均温度Ｔｓ（ａｖｇ）との差の絶対値を求め、その合計をサンプリングデータ数で除して平均偏差Ｔｓ（σ）を算出する。
【００２８】
浸水異常検知手段６１は、各熱電対Ｔ１０１〜Ｔ１３２について、前記平均温度Ｔｓ（ａｖｇ）が、下限値Ｔｍｉｎ＜平均温度Ｔｓ（ａｖｇ）＜上限値Ｔｍａｘの関係を満足し、且つ前記平均偏差Ｔｓ（σ）が所定値Ｐ以下（平均偏差Ｔｓ（σ）≦Ｐ）のときに、測温値の出力変化が１００°Ｃ前後の小さいばらつきで推移したものと判断して熱電対が浸水異常であることを検知し、オペレータ等に警報等を発するか、或いは当該熱電対を不使用状態にする信号を出力する。なお、下限値Ｔｍｉｎ及び上限値Ｔｍａｘについては、熱電対が浸水すると、１００°Ｃ前後の小さいばらつきに入る測定値を示すことから、例えば下限値Ｔｍｉｎを９８°Ｃ、上限値Ｔｍａｘを１０５°Ｃ程度に設定するが、これらは鋳込み状況に応じて適宜変更可能である。
【００２９】
図６に正常な熱電対及び浸水異常の熱電対における測温値と時間と鋳込速度との関係を示す。図から、正常な熱電対は、各測温点の測温値が鋳込速度に追従して上昇するが、浸水異常の熱電対については、鋳込速度が上昇しても一定温度（１００°Ｃ前後）になるとそれ以上上昇しなくなるのが判る。
次に、浸水検知用コントローラ３１の作動を図５を参照して説明する。
【００３０】
まず、ステップＳ１１では、各熱電対Ｔ１０１〜Ｔ１３２から測温値をサンプリングし、ステップＳ１２でサンプリングが完了すると、ステップＳ１３に移行する。
ステップＳ１３では、平均温度演算手段４１によって、各熱電対Ｔ１０１〜Ｔ１３２毎に測温値のサンプリングデータの合計をサンプリングデータ数で除して平均温度Ｔｓ（ａｖｇ）を算出し、ステップＳ１４に移行する。
【００３１】
ステップＳ１４では、平均偏差演算手段５１によって、各熱電対Ｔ１０１〜Ｔ１３２毎に全ての測温値のサンプリングデータについて、該サンプリングデータと前記平均温度Ｔｓ（ａｖｇ）との差の絶対値を求め、その合計をサンプリングデータ数で除して平均偏差Ｔｓ（σ）を算出し、ステップＳ１５に移行する。
ステップＳ１５では、浸水異常検知手段６１によって、各熱電対Ｔ１０１〜Ｔ１３２について、前記平均温度Ｔｓ（ａｖｇ）が、下限値Ｔｍｉｎ＜平均温度Ｔｓ（ａｖｇ）＜上限値Ｔｍａｘの関係を満足し、且つ前記平均偏差Ｔｓ（σ）が所定値Ｐ以下（平均偏差Ｔｓ（σ）≦Ｐ）であるか否かが判断され、下限値Ｔｍｉｎ＜平均温度Ｔｓ（ａｖｇ）＜上限値Ｔｍａｘ、且つ平均偏差Ｔｓ（σ）≦Ｐである場合は、測温値の出力変化が１００°Ｃ前後の小さいばらつきで推移したものと判断して熱電対が浸水異常であることを検知し、ステップＳ１６に移行してオペレータ等に警報等を発するか、或いは当該熱電対を不使用状態にする信号を出力する。
【００３２】
上記の説明から明らかなように、この実施の形態では、操業時の実際の溶鋼熱による熱電対の測温値の変化から熱電対の浸水異常を検知するようにしているので、熱電対の浸水異常をオンラインで正確に検知することができ、しかも、上記第１の態様の実施の形態のように、異常判定の成立回数の評価を行わなくて済むため、前記浸水異常の検知を迅速に行うことができる。
【００３３】
なお、上記第２の態様の実施の形態では、鋳型１の外面（銅板）に周方向に沿って複数の熱電対を一段取り付けた場合を例に採ったが、これに限定されず、上下二段或いは上下三段以上に熱電対を取り付けた場合にも本発明を適用してもよい。
次に、図７〜図９を参照して、本発明の第３の態様の実施の形態の一例である拘束性ブレークアウト予知用温度センサの異常検知方法を説明する。なお、上記第１の態様の実施の形態と重複する部分については、各図に同一符号を付して説明する。
【００３４】
図７において符号１は連続鋳造用鋳型、Ｔ１０１〜Ｔ１３２はこの鋳型１の外面（銅板）に周方向に沿って複数箇所埋設された熱電対（温度センサ）であり、各熱電対Ｔ１０１〜Ｔ１３２による測温値は鈍化検知用コントローラ３２によって例えば鋳造初期の所定時間、例えば、湯面到達時（溶鋼注入により熱電対を設置した高さに溶鋼が到達した時）から数十分の間、所定の周期でサンプリングされて所定のプログラムによる処理が実行される。
【００３５】
コントローラ３２は、温度変化率演算手段４２及び熱電対出力変化鈍化検知手段５２を備える。
温度変化率演算手段４２は、鋳造初期の湯面到達時から数十分の間、各熱電対Ｔ１０１〜Ｔ１３２毎に測温値データをサンプリングして、その温度変化率（ｄｅｇ／ｓｅｃ）を算出する。
【００３６】
熱電対出力変化鈍化検知手段５２は、前記温度変化率が予め実験や経験（過去の正常データ）等を基に定められた所定の値以下の場合に、好ましくは前記の場合に加えて更に、前記測温値の最高到達温度が予め実験や経験（過去の正常データ）等を基に定められた所定の値以下のときに、当該熱電対の温度変化に対する出力変化が、熱電対の劣化、熱電対のケーブルの異常、熱電対と鋳型外面（銅板）との接触不良、熱電対の浸水異常等により鈍化したことを検知し、オペレータ等に警報等を発するか、或いは当該熱電対を不使用状態にする信号を出力する。
なお、最高到達温度とは、湯面到達時から測温値が上昇していき、初めて下降を始める時点の測温値のことである。
【００３７】
図９に正常な熱電対及び鈍化異常の熱電対における鋳造初期の測温値と鋳込み時間との関係を示す。図から明らかなように、正常な熱電対は湯面到達時から急激に温度が上昇して最高到達温度も高いのに対し、鈍化異常の熱電対は湯面到達時からの温度変化率が低く、最高到達温度も低いのが判る。
次に、鈍化検知用コントローラ３２の作動を図８を参照して説明する。
【００３８】
まず、ステップＳ２１で湯面到達が検知されると、ステップＳ２２に移行して、各熱電対Ｔ１０１〜Ｔ１３２から測温値を所定時間（例えば数十分）サンプリングし、ステップＳ２３でサンプリングが完了すると、ステップＳ２４に移行する。
ステップＳ２４では、温度変化率演算手段４２によって、各熱電対Ｔ１０１〜Ｔ１３２毎にサンプリングされた測温値データを基に、その温度変化率（ｄｅｇ／ｓｅｃ）を算出し、ステップＳ２５に移行する。
【００３９】
ステップＳ２５では、熱電対出力変化鈍化検知手段５２によって、前記温度変化率が予め実験や経験（過去の正常データ）等を基に定められた所定の値以下で、あるいは更に前記測温値の最高到達温度が予め実験や経験（過去の正常データ）等を基に定められた所定の値以下であるか否かを判断し、前者あるいは両方を満足する場合は、当該熱電対の温度変化に対する出力変化が、熱電対の劣化、熱電対のケーブルの異常、熱電対と鋳型外面（銅板）との接触不良、熱電対の浸水異常等により鈍化したことを検知し、オペレータ等に警報等を発するか、或いは当該熱電対を不使用状態にする信号を出力する。
【００４０】
上記の説明から明らかなように、この実施の形態では、鋳造初期時の実際の溶鋼熱による熱電対の測温値を基に該熱電対の鈍化を検知するようにしているので、熱電対の出力変化の鈍化状態をオンラインで正確に、且つ鋳造初期に検知することができる。
なお、上記第３の態様の実施の形態では、鋳型１の外面（銅板）に周方向に沿って複数の熱電対を一段取り付けた場合を例に採ったが、これに限定されず、上下二段或いは上下三段以上に熱電対を取り付けた場合にも本発明を適用してもよい。
【００４１】
また、上記第３の態様の実施の形態では、熱電対出力変化鈍化検知手段５２が、前記温度変化率が所定の値以下で、あるいは更に前記測温値の最高到達温度が所定の値以下のときに、当該熱電対の温度変化に対する出力変化が鈍化したことを検知するようにしているが、熱電対出力変化鈍化検知手段５２が、前記温度変化率が所定の値以下のときに、当該熱電対の温度変化に対する出力変化が鈍化したことを検知するようにしてもよい。
【００４２】
【発明の効果】
上記の説明から明らかなように、請求項１の発明によれば、操業時の実際の溶鋼熱による温度センサの測温値の変化に基づく異常判定の成立回数を用いて前記温度センサの温度変化に対する出力（測温値の）変化の鈍化を検知するようにしているので、該温度センサの出力変化の鈍化状態をオンラインで正確に検知することができるという効果が得られる。
【００４３】
請求項２の発明では、操業時の実際の溶鋼熱による熱電対の測温値の変化から熱電対の浸水異常を検知するようにしているので、熱電対の浸水異常をオンラインで正確に検知することができ、しかも、請求項１の発明のように、異常判定の成立回数の評価を行わなくて済むため、前記浸水異常の検知を迅速に行うことができるという効果が得られる。
【００４４】
請求項３又は４の発明では、鋳造初期時の実際の溶鋼熱による温度センサの測温値を基に温度センサの鈍化を検知するようにしているので、該温度センサの出力変化の鈍化状態をオンラインで正確に、且つ鋳造初期に検知することができるという効果が得られる。
【図面の簡単な説明】
【図１】本発明の第１の態様の実施の形態の一例である拘束性ブレークアウト予知用温度センサの異常検知方法を説明するための説明図である。
【図２】熱電対出力変化鈍化検知手段の具体的作動を説明するためのフローチャート図である。
【図３】本発明の第２の態様の実施の形態の一例である拘束性ブレークアウト予知用温度センサの異常検知方法を説明するための説明図である。
【図４】熱電対の取付構造を説明するための断面図である。
【図５】浸水検知用コントローラの作動を説明するためのフローチャート図である。
【図６】正常な熱電対及び浸水異常の熱電対における測温値と時間と鋳込み速度との関係を示すグラフ図である。
【図７】本発明の第３の態様の実施の形態の一例である拘束性ブレークアウト予知用温度センサの異常検知方法を説明するための説明図である。
【図８】鈍化検知用コントローラの作動を説明するためのフローチャート図である。
【図９】正常な熱電対及び鈍化異常の熱電対における鋳造初期の測温値と連続鋳造時の経過時間との関係を示すグラフ図である。
【符号の説明】
１…連続鋳造用鋳型
３…コントローラ
４…Ｆ（σ）演算手段
５…測温値変化異常判定手段
６…拘束性ブレークアウト判定手段
７…熱電対出力変化鈍化検知手段
３１…浸水検知用コントローラ
４１…平均温度演算手段
５１…平均偏差演算手段
６１…浸水異常検知手段
３２…鈍化検知用コントローラ
４２…温度変化率演算手段
５２…熱電対出力変化鈍化検知手段
Ｔ１０１〜Ｔ１３２…熱電対（温度センサ）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for detecting an abnormality of a temperature sensor used for predicting a constraint breakout of a continuous casting facility.
[0002]
[Prior art]
Constraint breakout means that during continuous casting, seizure occurs between the mold and slab due to poor lubrication due to poor flow of mold powder between the mold and slab, and when the slab is pulled down It means that the molten steel in the mold leaks to the outside when the solidified shell of the baked portion breaks and the broken portion is exposed from the lower end of the mold.
[0003]
If this restraint breakout occurs during continuous casting, it will cause interruption of casting and damage to equipment, resulting in reduced productivity. Conventionally, multiple thermocouples (temperature sensors) are embedded on the outer surface of the mold. To detect abnormalities in the change of the temperature measurement value by the thermocouple, estimate the occurrence of restrictive breakout based on the detection result, issue an alarm or the like, and take measures such as reducing the casting speed. .
[0004]
By the way, when the thermocouple deteriorates, the cable of the thermocouple is abnormal, the contact between the thermocouple and the outer surface of the mold (copper plate) is poor, or the thermocouple is abnormally immersed, etc. The output change slows down, that is, the output change becomes smaller than the normal thermocouple, causing a time lag, etc., and the accuracy of the abnormality detection of the temperature measurement value change by the thermocouple decreases, and the prediction of the restrictive breakout is predicted. Reliability will be impaired.
[0005]
In this case, a method of determining whether the thermocouple is normal or abnormal by inspecting the thermocouple alone has been proposed (for example, see Patent Document 1). However, in this case, the thermocouple is attached to the outer surface of the mold with the thermocouple attached thereto. Conventionally, the thermocouple is attached to the outer surface of the mold because it is not possible to inspect for deterioration, abnormalities in the thermocouple cable, poor contact between the thermocouple and the outer surface of the mold (copper plate), and abnormal water infiltration of the thermocouple. There has been proposed a thermocouple which is heated by steam or a burner to determine whether the thermocouple is normal or abnormal based on an output change thereof (for example, see Patent Document 2).
[0006]
[Patent Document 1]
JP-A-6-137956
[Patent Document 2]
JP-A-8-159883
[0007]
[Problems to be solved by the invention]
However, even if the thermocouple is heated with steam or a burner as described in Patent Document 2, it does not shock-heat the thermocouple through the mold with the actual molten steel heat. It is difficult to obtain a significant difference in the output change from the thermocouple, and even if the abnormality of the thermocouple can be determined, the output changes due to the gradual deterioration and cooling water etc. There is an inconvenience that a slowing down thermocouple cannot be detected.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a first object of the present invention is to provide a constraint breakout prediction system capable of accurately detecting, on-line, a slowdown of an output change with respect to a temperature change of a temperature sensor. An object of the present invention is to provide a temperature sensor abnormality detection method.
It is a second object of the present invention to provide a method for detecting an abnormality of a temperature sensor for predicting restrictive breakout, which can accurately and promptly detect inundation abnormality of a temperature sensor online.
Further, a third object of the present invention is to provide a method for detecting an abnormality of a temperature sensor for predicting restraint breakout, which is capable of accurately detecting, at an early stage of casting, a slowdown of an output change with respect to a temperature change of a temperature sensor. Is to do.
[0009]
[Means for Solving the Problems]
In order to achieve the first object, the invention according to claim 1 is provided when a change in a temperature measurement value during operation by a plurality of temperature sensors attached to a mold of a continuous casting facility satisfies a predetermined condition. Abnormality detection of a restrictive breakout prediction temperature sensor for detecting an abnormal slowdown of a change in a temperature measurement value with respect to a temperature change of the temperature sensor when predicting a restrictive breakout based on a result of the abnormality determination. The method,
A comparison is made between the number of times the abnormality determination of the change in the temperature measurement value of the two temperature sensors arranged at different positions is established, and the number of establishments of the temperature sensor having the greater number of occurrences is set to a predetermined number or more. When the relationship between the number of establishments of the temperature sensor having the larger number of establishments and the number of establishments of the temperature sensor having the smaller number of establishments satisfies a predetermined condition, the number of establishments smaller is smaller. Detecting that the change in the temperature measurement value with respect to the temperature change of the temperature sensor has abnormally slowed down.
[0010]
In order to achieve the second object, the invention according to claim 2 is characterized in that when a change in a temperature measurement value during operation by a plurality of temperature sensors attached to a mold of a continuous casting facility satisfies a predetermined condition. An abnormality detection method of a temperature sensor for restrictive breakout prediction for detecting a submergence abnormality of the temperature sensor when predicting a restrictive breakout based on the abnormality determination result based on the abnormality determination result,
An average temperature of the temperature measurement values of the temperature sensor sampled at a predetermined cycle is calculated, and an average deviation of the temperature measurement values is calculated, the average temperature is within a predetermined temperature range, and the average deviation is a predetermined value. It is characterized in that when the value is equal to or less than the value, it is detected that the temperature sensor is abnormal.
[0011]
In order to achieve the third object, the invention according to claim 3 is characterized in that when a change in a temperature measurement value during operation by a plurality of temperature sensors attached to a mold of a continuous casting facility satisfies a predetermined condition. An abnormality detection method for a constrained breakout prediction temperature sensor for detecting an abnormal slowdown of an output change with respect to a temperature change of the temperature sensor when predicting a constrained breakout based on a result of the abnormality determination. hand,
Calculating a temperature change rate of a temperature measurement value of the temperature sensor at an early stage of casting of the temperature sensor, and when the temperature change rate is equal to or less than a predetermined value, detecting that the output change with respect to the temperature change of the temperature sensor has slowed down. And
According to a fourth aspect of the present invention, in the third aspect, the output change with respect to the temperature change of the temperature sensor is slowed down when the highest attained temperature of the temperature sensor in the initial casting of the temperature sensor is equal to or less than a predetermined value. It is characterized by detecting.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram for explaining a method for detecting an abnormality of a temperature sensor for predicting restrictive breakout, which is an example of an embodiment of the first aspect of the present invention. FIG. 2 is a diagram showing a change in thermocouple output (temperature measurement value). FIG. 3 is a flow chart for explaining the operation of the dulling detecting means, and FIG. 3 is an explanatory view for explaining an abnormality detecting method of the temperature sensor for predicting restrictive breakout which is an example of the embodiment of the second aspect of the present invention. FIG. 4 is a cross-sectional view for explaining the mounting structure of the thermocouple, FIG. 5 is a flowchart for explaining the operation of the controller for detecting inundation, and FIG. FIG. 7 is a graph showing the relationship between values, time, and pouring speed. FIG. 7 is an explanatory diagram for describing an abnormality detection method of a temperature sensor for predicting restrictive breakout which is an example of an embodiment of the third aspect of the present invention. Figures and 8 are slowed down Flow chart for explaining the operation of the knowledge controller, FIG. 9 is a graph showing the relationship between the elapsed time during continuous casting and casting the initial temperature measurement values in normal thermocouple and slowing abnormal thermocouple.
[0013]
First, the embodiment of the first aspect of the present invention will be described. In FIG. 1, reference numeral 1 denotes a mold for continuous casting, and T101 to T132 are embedded at a plurality of locations along the circumferential direction on the outer surface (copper plate) of the mold 1. The temperature measurement values T obtained by the thermocouples T101 to T132 are sampled by the controller 3 at a predetermined cycle, and the processing by a predetermined program is executed.
The controller 3 includes an F (σ) calculation unit 4, a temperature measurement value change abnormality determination unit 5, a restrictive breakout determination unit 6, and a thermocouple output (temperature measurement value) change slowdown detection unit 7.
[0014]
The temperature-measurement-value-change-abnormality determination means 5 determines whether or not the change in the temperature measurement value during operation is abnormal for each of the thermocouples T101 to T132. The following equations (1) and (2) When both of the conditions are satisfied, it is determined that the change in the temperature measurement value is abnormal, and based on the abnormality determination result, the restrictive breakout determining means 6 determines whether or not the restrictive breakout is a restrictive breakout using a known determination logic. If a restraint breakout is detected, an alarm is displayed on a monitor screen or the like, a signal that generates an alarm sound is output, and when this alarm is recognized, the pouring speed is reduced. Is applied.
[0015]
T _i ≧ F (σ) (1)
T _i -T _i-1 ≧ ΔT (2)
Here, F (σ): the value given by the F (σ) calculation means 4 _i Threshold value (variation value)
T _i : Latest temperature measurement value
T _i-1 : Previous temperature measurement
ΔT: threshold value (fixed value: about two to three times the minimum temperature measurement unit of the thermocouple) F (σ) calculation means 4 calculates the latest temperature measurement value T _i A function F (σ) is calculated for each thermocouple T101 to T132 and for each sampling cycle, using the standard deviation σ of the temperature measurement value of a certain period (for example, 10 points) in the past in the past as a variable. It is calculated by 3).
[0016]
F (σ) = T (avg) + kσ (3)
Here, T (avg): latest temperature measurement value T _i Average value of temperature measurement values for a certain period in the past (for example, 10 points)
σ: Latest temperature measurement value T _i Standard deviation of temperature measurement values for a certain period in the past (for example, 10 points)
k: a constant empirically determined from the relationship between the temperature measurement value and the breakout mark, etc., and is set to k = 3 in this embodiment.
[0017]
For each of the thermocouples T101 to T132, F (σ) calculated by the F (σ) calculation means 4 based on each temperature measurement value is changed according to the variation in the responsiveness of the thermocouples T101 to T132, and the sampling period is changed. It is updated every time and fluctuates according to the casting state.
The thermocouple output change slowdown detecting means 7 compares the number of times that the temperature measurement value change abnormality determination means 5 has made an abnormality determination of the temperature measurement value change by the two thermocouples arranged at different positions, and has a large number of times. A ratio obtained by dividing the number of formations of the thermocouple having the larger number of times by the number of formations of the thermocouple having the smaller number of formations by the number of formations of the thermocouple having the smaller number of formations is a predetermined value. When the temperature is equal to or higher than H, the change in output with respect to the temperature change of the thermocouple having the smaller number of occurrences is caused by deterioration of the thermocouple, abnormality of the thermocouple cable, poor contact between the thermocouple and the outer surface of the mold (copper plate), Detects slowdown due to abnormal flooding.
[0018]
There is no particular limitation on the combination of the two thermocouples arranged at different positions, but the most preferable combination of the thermocouples is a pair facing the short side or the long side direction of the mold 1. In FIG. 1, a pair of thermocouples T103 and T128 facing in the short side direction and a pair of thermocouples T131 and T116 facing in the long side direction can be exemplified.
A pair of thermocouples facing in the short side or long side direction of the mold 1 shows a similar change in the temperature measurement value when there is no abnormality in the thermocouples. Therefore, the abnormality of one thermocouple can be detected sensitively. Of course, another pair, for example an adjacent pair, can be selected. Further, in order to detect the dulling of one thermocouple, at the same time as selecting a pair of thermocouples and a pair of thermocouples facing in the short side or long side direction and providing the detection, at the same time, from the thermocouple and the adjacent thermocouple A pair may be selected for the detection.
[0019]
Next, the specific operation of the thermocouple output change slowdown detecting means 7 will be described with reference to FIG. Here, a pair of thermocouples T103 and T128 facing each other in the short side direction of the mold 1 will be described as an example.
First, in step S1, the temperature measurement value change abnormality determination means 5 determines the number of times the abnormality determination of the temperature measurement value change of the thermocouple T103 is made. ₁ And the number N of times the temperature measurement value change of the thermocouple T128 is determined to be abnormal by the temperature measurement value change abnormality determination means 5 ₂ And N ₁ > N ₂ In the case of, the process proceeds to step S2, and N ₁ > N ₂ If not, the process proceeds to step S5.
[0020]
In step S2, the number of times N that the abnormality determination is made in the thermocouple T103 is N ₁ Is determined to be equal to or greater than a predetermined number n determined in advance by experiments, experiences, and the like. ₁ If ≧ n, the process proceeds to step S3. In step S3, the number of times N that the abnormality determination has been made in the thermocouple T103 is N ₁ Is the number of times N that the abnormality determination has been made in the thermocouple T128. ₂ Ratio N divided by ₁ / N ₂ Is determined to be greater than or equal to a predetermined ratio H determined in advance by experiment, experience, or the like. ₁ / N ₂ If ≧ H, the output change with respect to the temperature change of the thermocouple T128 slows down due to deterioration of the thermocouple, abnormality of the cable of the thermocouple, poor contact between the thermocouple and the outer surface of the mold (copper plate), abnormality of the thermocouple inundation, and the like. Is detected (step S4), an alarm or the like is issued to an operator or the like, or a signal for disabling the thermocouple T128 is output.
[0021]
On the other hand, in step S5, the number N of times of the abnormality determination by the temperature-measurement-value-change abnormality determination means 5 for the temperature-measurement-value change of the thermocouple T103 is N ₁ And the number N of times the temperature measurement value change of the thermocouple T128 is determined to be abnormal by the temperature measurement value change abnormality determination means 5 ₂ And N ₂ > N ₁ If so, the process proceeds to step S6.
In step S6, the number of times N that the abnormality determination has been made in the thermocouple T128 is N ₂ Is determined to be equal to or greater than a predetermined number n determined in advance by experiments, experiences, and the like. ₂ If ≧ n, the process proceeds to step S7. In step S7, the number N of times of occurrence of the abnormality determination in the thermocouple T128 is determined. ₂ Is the number of occurrences N of the above-described abnormality determination in the thermocouple T103. ₁ Ratio N divided by ₂ / N ₁ Is determined to be greater than or equal to a predetermined ratio H determined in advance by experiment, experience, or the like. ₂ / N ₁ If ≧ H, the output change with respect to the temperature change of the thermocouple T103 slows down due to deterioration of the thermocouple, abnormality of the cable of the thermocouple, poor contact between the thermocouple and the outer surface of the mold (copper plate), abnormality of the thermocouple inundation, and the like. Is detected (step S8), and an alarm is issued to an operator or the like, or a signal for disabling the thermocouple T103 is output.
[0022]
As is clear from the above description, in this embodiment, the output change with respect to the temperature change of the thermocouple is performed by using the number of times of performing the abnormality determination based on the change in the temperature measurement value of the thermocouple due to the actual molten steel heat during operation. Of thermocouple deterioration, thermocouple cable abnormality, poor contact between thermocouple and mold outer surface (copper plate), thermocouple output change due to thermocouple inundation abnormality, etc. Can be accurately detected online.
[0023]
In the embodiment of the first aspect, a case where a plurality of thermocouples are mounted in one step along the circumferential direction on the outer surface (copper plate) of the mold 1 is taken as an example. However, the present invention is not limited to this. The present invention may be applied to a case where thermocouples are attached to three or more stages or three or more stages.
Further, in the embodiment of the first aspect, the abnormality determination of the temperature measurement value change of each of the thermocouples T101 to T132 by the temperature measurement value change abnormality determination means 5 is based on both of the above equations (1) and (2). Although it is assumed that the condition is satisfied, the present invention is not limited to this, and another known determination logic may be used to determine an abnormality in the temperature measurement value change of each of the thermocouples T101 to T132.
[0024]
Further, in the embodiment of the first aspect, when the ratio obtained by dividing the number of establishments of the thermocouple having the larger number of times by the number of establishments of the thermocouple having the smaller number of times is equal to or more than the predetermined value H, Although it is configured to detect that the output change with respect to the temperature change of the thermocouple with the smaller number of occurrences has slowed down, instead of this, a certain period (for example, 1 day, 2 days, 1 week depending on the operation status) Etc.), the difference between the number of times of establishment of the thermocouple with the larger number of times of establishment and the number of times of establishment of the thermocouple with the smaller number of times of occurrence is determined. You may make it detect that the output change with respect to the temperature change of the smaller thermocouple slowed down.
[0025]
Next, with reference to FIGS. 3 to 6, a description will be given of a method of detecting an abnormality of the temperature sensor for predicting a restrictive breakout, which is an example of the embodiment of the second aspect of the present invention. In addition, about the part which overlaps with embodiment of said 1st aspect, the same code | symbol is attached | subjected to each figure and is demonstrated.
In FIG. 3, reference numeral 1 denotes a continuous casting mold, and T101 to T132 denote thermocouples (temperature sensors) buried at a plurality of locations along the circumferential direction on the outer surface (copper plate) of the mold 1. The temperature measurement value is sampled by the flood detection controller 31 at a predetermined cycle, for example, every several hours of a flood logic cycle, and a process by a predetermined program is executed.
[0026]
Since the thermocouples T101 to T132 have the same structure, the thermocouple T101 will be described. The thermocouple T101 fixes the copper plate of the mold 1 and the backup frame (water box) 20 as shown in FIG. The shaft core of the stud bolt 21 is hollowed out, is detachably attached in a state of being passed through the hole and pressed against the outer surface of the mold 1 by a spring 22, and water entering the hollow stud bolt 21. In this case, the thermocouple is in a submerged state, and the output changes abnormally (measurement cannot be made at temperatures above the boiling point of water). In FIG. 4, reference numeral 23 denotes an O-ring interposed between the tip of the stud bolt 21 and the outer surface of the mold 1, and reference numeral 24 denotes a cooling water groove.
[0027]
The controller 31 includes an average temperature calculating unit 41, an average deviation calculating unit 51, and an inundation abnormality detecting unit 61.
The average temperature calculating means 41 calculates the average temperature Ts (avg) by dividing the total of the sampling data of the temperature measurement values by the number of sampling data for each of the thermocouples T101 to T132.
The average deviation calculating means 51 calculates the absolute value of the difference between the sampled data and the average temperature Ts (avg) for the sampled data of all the temperature values for each of the thermocouples T101 to T132, and sums the sum to the sampled data. The average deviation Ts (σ) is calculated by dividing by the number.
[0028]
The inundation abnormality detecting means 61 determines that the average temperature Ts (avg) of each of the thermocouples T101 to T132 satisfies the relationship of lower limit Tmin <average temperature Ts (avg) <upper limit Tmax, and the average deviation Ts ( σ) is equal to or smaller than a predetermined value P (average deviation Ts (σ) ≦ P), it is determined that the output change of the temperature measurement value has changed with a small variation of about 100 ° C., and the thermocouple is abnormally flooded. Then, an alarm or the like is issued to an operator or the like, or a signal for disabling the thermocouple is output. Note that the lower limit value Tmin and the upper limit value Tmax indicate measured values that fall into small variations around 100 ° C. when the thermocouple is submerged. For example, the lower limit value Tmin is 98 ° C. and the upper limit value Tmax is 105 ° C. Although they are set to the degree, these can be changed appropriately according to the casting state.
[0029]
FIG. 6 shows the relationship between the temperature measurement value, the time, and the casting speed in a normal thermocouple and a thermocouple having an abnormal flooding. From the figure, it can be seen that the temperature value at each temperature measuring point of the normal thermocouple rises following the pouring speed, but that of the thermocouple with abnormal water infiltration has a constant temperature (100 °) even if the pouring speed increases. It can be seen that it does not rise any more when it reaches (C).
Next, the operation of the flood detection controller 31 will be described with reference to FIG.
[0030]
First, in step S11, a temperature measurement value is sampled from each of the thermocouples T101 to T132, and when the sampling is completed in step S12, the process proceeds to step S13.
In step S13, the average temperature calculating means 41 calculates the average temperature Ts (avg) by dividing the sum of the sampling data of the temperature measurement values for each of the thermocouples T101 to T132 by the number of sampling data, and proceeds to step S14. .
[0031]
In step S14, the average deviation calculating means 51 obtains the absolute value of the difference between the sampled data and the average temperature Ts (avg) for the sampled data of all the temperature measurement values for each of the thermocouples T101 to T132. The total is divided by the number of sampling data to calculate an average deviation Ts (σ), and the process proceeds to step S15.
In step S15, the average temperature Ts (avg) for each of the thermocouples T101 to T132 satisfies the relationship of lower limit Tmin <average temperature Ts (avg) <upper limit Tmax for the thermocouples T101 to T132, and It is determined whether the average deviation Ts (σ) is equal to or less than a predetermined value P (average deviation Ts (σ) ≦ P), and the lower limit Tmin <the average temperature Ts (avg) <the upper limit Tmax, and the average deviation Ts ( σ) ≦ P, it is determined that the output change of the temperature measurement value has changed with a small variation of about 100 ° C., and it is detected that the thermocouple is inundated. Or the like, or outputs a signal for disabling the thermocouple.
[0032]
As is clear from the above description, in this embodiment, the thermocouple is detected from a change in the temperature value of the thermocouple due to the actual molten steel heat during operation. An abnormality can be accurately detected online, and the number of times the abnormality determination has been made need not be evaluated as in the embodiment of the first aspect, so that the inundation abnormality is quickly detected. be able to.
[0033]
Note that, in the embodiment of the second aspect, a case where a plurality of thermocouples are mounted in one step along the circumferential direction on the outer surface (copper plate) of the mold 1 is taken as an example, but the present invention is not limited to this. The present invention may be applied to a case where thermocouples are attached to three or more stages or three or more stages.
Next, with reference to FIGS. 7 to 9, a description will be given of an abnormality detection method of the temperature sensor for predicting a restrictive breakout which is an example of the embodiment of the third aspect of the present invention. In addition, about the part which overlaps with embodiment of said 1st aspect, the same code | symbol is attached | subjected to each figure and is demonstrated.
[0034]
In FIG. 7, reference numeral 1 denotes a mold for continuous casting, and T101 to T132 denote thermocouples (temperature sensors) buried at a plurality of locations along the circumferential direction on the outer surface (copper plate) of the mold 1, and each thermocouple T101 to T132. The temperature measurement value is determined by the blunting detection controller 32 for a predetermined time, for example, from a time when the molten steel reaches the molten metal surface (when the molten steel reaches the height at which the thermocouple is installed by the injection of the molten steel), for several tens of minutes. Sampling is performed periodically, and processing by a predetermined program is executed.
[0035]
The controller 32 includes a temperature change rate calculation unit 42 and a thermocouple output change slowdown detection unit 52.
The temperature change rate calculating means 42 samples temperature measurement value data for each of the thermocouples T101 to T132 for several tens of minutes from when the molten metal surface reaches the initial casting level, and calculates the temperature change rate (deg / sec). I do.
[0036]
The thermocouple output change slowdown detecting means 52 is provided when the temperature change rate is equal to or less than a predetermined value determined in advance based on experiments or experiences (normal data in the past) and the like. When the maximum temperature of the temperature measurement value is equal to or less than a predetermined value determined in advance based on experiments, experiences (past normal data), and the like, the output change with respect to the temperature change of the thermocouple causes deterioration of the thermocouple, Detects an abnormality in the thermocouple cable, poor contact between the thermocouple and the outer surface of the mold (copper plate), dulling due to abnormal infiltration of the thermocouple, etc., and issues an alarm to the operator, etc., or does not use the thermocouple. Outputs the signal to be set.
Note that the maximum temperature is a temperature measured value at the time when the measured temperature starts rising from the time when the molten metal surface is reached and starts decreasing for the first time.
[0037]
FIG. 9 shows the relationship between the temperature measurement value in the initial casting and the casting time in a normal thermocouple and a thermocouple having a dulling abnormality. As is clear from the figure, the normal thermocouple rapidly rises in temperature from the time of reaching the surface and the maximum temperature is high, whereas the thermocouple with the blunting abnormality has a low rate of temperature change from the time of arrival at the surface. It can be seen that the maximum temperature is low.
Next, the operation of the blunting detection controller 32 will be described with reference to FIG.
[0038]
First, when arrival at the molten metal surface is detected in step S21, the process proceeds to step S22, where the temperature measurement values are sampled from the thermocouples T101 to T132 for a predetermined time (for example, several tens of minutes), and when the sampling is completed in step S23. Then, the process proceeds to step S24.
In step S24, the temperature change rate calculating unit 42 calculates the temperature change rate (deg / sec) based on the temperature measurement value data sampled for each of the thermocouples T101 to T132, and then proceeds to step S25.
[0039]
In step S25, the thermocouple output change slowdown detecting means 52 determines that the temperature change rate is equal to or less than a predetermined value determined in advance based on experiments and experiences (past normal data), or the maximum of the temperature measurement value. It is determined whether the attained temperature is equal to or lower than a predetermined value determined based on experiments, experiences (past normal data), and the like. If the former or both are satisfied, the output corresponding to the temperature change of the thermocouple is output. Detects whether the change has slowed down due to deterioration of the thermocouple, abnormality of the cable of the thermocouple, poor contact between the thermocouple and the outer surface of the mold (copper plate), abnormality of the thermocouple inundation, etc., and issues an alarm to an operator or the like. Alternatively, a signal for putting the thermocouple in an unused state is output.
[0040]
As is apparent from the above description, in this embodiment, the thermocouple is detected based on the measured value of the thermocouple due to the actual molten steel heat at the beginning of casting, so that the thermocouple slowdown is detected. The blunted state of the output change can be accurately detected online and at the beginning of casting.
In the embodiment of the third aspect, a case is described in which a plurality of thermocouples are mounted in one step along the circumferential direction on the outer surface (copper plate) of the mold 1, but the present invention is not limited to this. The present invention may be applied to a case where thermocouples are attached to three or more stages or three or more stages.
[0041]
Further, in the embodiment of the third aspect, the thermocouple output change slowdown detecting means 52 determines that the temperature change rate is equal to or less than a predetermined value, or further, the maximum temperature of the temperature measurement value is equal to or less than a predetermined value. Sometimes, it is detected that the output change with respect to the temperature change of the thermocouple has slowed, but the thermocouple output change slowdown detecting means 52 detects the thermocouple when the temperature change rate is equal to or less than a predetermined value. You may make it detect that the output change with respect to the temperature change of a pair slowed down.
[0042]
【The invention's effect】
As is apparent from the above description, according to the first aspect of the present invention, the temperature change of the temperature sensor is performed by using the number of times of performing the abnormality determination based on the change of the temperature measurement value of the temperature sensor due to the actual molten steel heat during operation. Is detected so that the change in the output (temperature measurement value) of the temperature sensor slows down, so that the effect that the state of the change in the output change of the temperature sensor can be accurately detected online can be obtained.
[0043]
According to the second aspect of the present invention, the abnormality in the thermocouple inundation is detected from the change in the temperature measurement value of the thermocouple due to the actual heat of the molten steel during the operation, so that the abnormality in the thermocouple inundation is accurately detected online. In addition, since it is not necessary to evaluate the number of times the abnormality determination has been made as in the first aspect of the present invention, the effect of quickly detecting the inundation abnormality can be obtained.
[0044]
According to the third or fourth aspect of the present invention, the slowdown of the temperature sensor is detected based on the temperature measurement value of the temperature sensor due to the actual heat of molten steel at the beginning of casting. The effect is obtained that it can be detected accurately online and at the beginning of casting.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating a method for detecting an abnormality of a temperature sensor for predicting a restrictive breakout, which is an example of an embodiment of the first aspect of the present invention.
FIG. 2 is a flowchart for explaining a specific operation of a thermocouple output change slowdown detecting unit.
FIG. 3 is an explanatory diagram for describing an abnormality detection method of a temperature sensor for predicting a restrictive breakout, which is an example of an embodiment of the second aspect of the present invention.
FIG. 4 is a cross-sectional view for describing a thermocouple mounting structure.
FIG. 5 is a flowchart for explaining the operation of a water intrusion detection controller.
FIG. 6 is a graph showing a relationship between a temperature measurement value, a time, and a casting speed in a normal thermocouple and a thermocouple having an abnormal flooding.
FIG. 7 is an explanatory diagram for describing an abnormality detection method of a temperature sensor for predicting restrictive breakout, which is an example of an embodiment of the third aspect of the present invention.
FIG. 8 is a flowchart for explaining the operation of the controller for detecting the dulling.
FIG. 9 is a graph showing the relationship between the temperature measured at the beginning of casting and the elapsed time during continuous casting in a normal thermocouple and a thermocouple having a dulling abnormality.
[Explanation of symbols]
1: Mold for continuous casting
3. Controller
4 ... F (σ) calculation means
5 ... Temperature measurement value change abnormality determination means
6: Restrictive breakout determination means
7 ... Thermocouple output change slowdown detecting means
31 ... Inundation detection controller
41 ... Mean temperature calculating means
51 Mean deviation calculating means
61 ... Inundation abnormality detection means
32 ... Controller for slowdown detection
42 ... temperature change rate calculating means
52: Thermocouple output change slowdown detecting means
T101 to T132: thermocouple (temperature sensor)

Claims

When a change in the temperature measurement value during operation by a plurality of temperature sensors attached to the mold of the continuous casting facility satisfies a predetermined condition, it is determined to be abnormal, and a restraint breakout is predicted based on the abnormality determination result. In the meantime, a method for detecting an abnormality of the temperature sensor for restrictive breakout prediction for detecting an abnormal slowdown of the change in the temperature measurement value with respect to the temperature change of the temperature sensor,
A comparison is made between the number of times the abnormality determination of the change in the temperature measurement value of the two temperature sensors arranged at different positions is established, and the number of establishments of the temperature sensor having the greater number of occurrences is set to a predetermined number or more. When the relationship between the number of establishments of the temperature sensor having the larger number of establishments and the number of establishments of the temperature sensor having the smaller number of establishments satisfies a predetermined condition, the number of establishments smaller is smaller. Detecting a change in the temperature measurement value with respect to a change in the temperature of the temperature sensor abnormally slowed down.

When a change in the temperature measurement value during operation by a plurality of temperature sensors attached to the mold of the continuous casting facility satisfies a predetermined condition, it is determined to be abnormal, and a restraint breakout is predicted based on the abnormality determination result. In the meantime, a method for detecting an abnormality of the temperature sensor for constrained breakout prediction for detecting inundation abnormality of the temperature sensor,
An average temperature of the temperature measurement values of the temperature sensor sampled at a predetermined cycle is calculated, and an average deviation of the temperature measurement values is calculated, the average temperature is within a predetermined temperature range, and the average deviation is a predetermined value. A method of detecting an abnormality in the temperature sensor for predicting a restrictive breakout, wherein the abnormality is detected when the temperature sensor is below the value of.

When a change in the temperature measurement value during operation by a plurality of temperature sensors attached to the mold of the continuous casting facility satisfies a predetermined condition, it is determined to be abnormal, and a restraint breakout is predicted based on the abnormality determination result. In the meantime, a method for detecting an abnormality of the temperature sensor for restrictive breakout prediction for detecting abnormal slowdown of an output change with respect to a temperature change of the temperature sensor,
Calculating a temperature change rate of a temperature measurement value of the temperature sensor at an early stage of casting of the temperature sensor, and when the temperature change rate is equal to or less than a predetermined value, detecting that the output change with respect to the temperature change of the temperature sensor has slowed down. Abnormality detection method of temperature sensor for predicting restraint breakout.

4. The restraint according to claim 3, wherein when the maximum temperature of the temperature measurement value at the initial stage of casting of the temperature sensor is equal to or lower than a predetermined value, it is detected that the output change with respect to the temperature change of the temperature sensor has slowed down. Detection method of temperature sensor for predicting susceptibility breakout.