JP2004050217A - Tension controller for tandem rolling mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable highly accurate control of the tension of a rolled stock without using tension control with loopers. <P>SOLUTION: In this tension controller, the tension of a rolled stock is calculated from any of the output of a tension detector installed between rolling stands, the output of a tension detector attached to a looper device installed between the rolling stands or electric power for driving the loopers, and the tension of the rolled stock is controlled by using the tension of the rolled stock thus calculated. <P>COPYRIGHT: (C)2004,JPO

Description

によって行う。ここで、Ｈはスタンド入厚（スタンド入側板厚）、ｈはスタンド出厚（スタンド出側板厚）、ｂは板幅、ｋは変形抵抗である。
【００１７】
圧延トルクに対する影響係数ベクトルを、
【数３】

とし、圧延荷重に対する影響係数ベクトルを
【数４】

とし、ロックオン値からのベクトルＸ_ｉの偏差を、
【数５】

とする。ここで、Ｈ_ｉ０、ｈ_ｉ０、ｂ_ｉ０、ｋ_ｉ０はそれぞれロックオン（メモリー）値である。なお、一般に板幅変化は小さいものとして、考慮の対象から外すことが多い。
【００１８】
ロックオン時の無張力状態での圧延荷重および圧延トルクをそれぞれＰ_ｉ０およびＧ_ｉ０とおき、これらの値を圧延状態の変化に応じて修正し、圧延中の圧延荷重Ｐ_ｉ０ ^Ｍおよび圧延トルクＧ_ｉ０ ^Ｍを、
Ｐ_ｉ０ ^Ｍ＝Ｐ_ｉ０＋Ｚ_ｉ・△Ｘ_ｉ　　　　　　　　　　　　　…（８）
Ｇ_ｉ０ ^Ｍ＝Ｇ_ｉ０＋Ｙ_ｉ・△Ｘ_ｉ　　　　　　　　　　　　　…（９）
として推定する。
【００１９】
これにより、（１）式、（２）式および（３）式はそれぞれ、
Ｐ_ｉ＝Ｐ_ｉ０ ^Ｍ−α_ｉ・ｔ_ｉ−β_ｉ・ｔ_ｉ−１　　　　　　…（１０）
Ｇ_ｉ＝Ｇ_ｉ０ ^Ｍ−γ_ｉ・ｔ_ｉ＋δ_ｉ・ｔ_ｉ−１　　　　　　…（１１）
Ｇ_ｉ０ ^Ｍ＝Ａ_ｉ０ ^Ｍ・Ｐ_ｉ０ ^Ｍ　　　　　　　　　　　　　　…（１２）
のように修正される。
【００２０】
（１０）式、（１１）式および（１２）式から張力の推定式として次式が得られる。すなわち、
・後方張力ｔ_ｉ−１から前方張力ｔ_ｉを推定する式として、
【数６】

・前方張力ｔ_ｉから後方張力ｔ_ｉ−１を推定する式として、
【数７】

ＮＯ．ｉスタンド２ｂおよびＮＯ．ｉ−１スタンド２ａ間では、
【数８】

（１３）式から圧延荷重、圧延トルクおよび後方張力を用いて前方張力を推定することができる。これは後方張力を測定することができる場合に適用可能なものである。同様に（１４）式および（１５）式から圧延荷重、圧延トルクおよび前方張力を用いて後方張力を推定することができる。これは前方張力を測定できる場合に適用可能なものである。
【００２１】
図１１を用いてルーパレス制御における張力推定の概念について説明する。圧延中は張力が印加された状態での圧延荷重Ｐ_ｉと圧延トルクＧ_ｉしか測定することができないが、ｉ＋１スタンドオンの点Ａ以前の無張力時の圧延荷重Ｐ_ｉ０および圧延トルクＧ_ｉ０を保存しておき、ｉ＋１スタンドオンの点Ａ以後のそれらの変化分ΔＲを用いて、影響係数を用いた演算式で張力を推定するものである。
【００２２】
一方、特公平２−１４１２４号公報には、オンライン最小二乗法によりトルクアームを計算して、圧延材のスタンド間張力を推定する方法が開示されている。しかし、この方法では、圧延状態を表す基本式に含まれる張力項を消去するために、全スタンド間の張力演算を行うことを前提としており、部分的に適用したい場合には適用できないことになる。
【００２３】
【発明が解決しようとする課題】
上述したルーパレス張力推定方式では、圧延荷重と圧延トルクのほかに前方張力あるいは後方張力が必要である。たとえば、ルーパレス制御を連続して行う場合、前方張力あるいは後方張力は推定値であり、この推定値に基づいてさらに張力を推定することは、推定精度を劣化させる原因となり得る。
【００２４】
また連続したスタンド間でルーパレス制御を実施するとき、下流側のスタンド間ではすでに後方張力が発生しているため、無張力状態での圧延荷重と圧延トルクを実測することができなくなり、影響係数を使用して、無張力状態での圧延荷重および圧延トルクの推定をしなければならない。このとき影響係数や、推定した張力値により、無張力状態での圧延荷重と圧延トルクからの張力推定値は誤差を含むことになる。このため下流側に行くに従って、張力推定精度が低下する。さらに影響係数は、一般に圧延材先端における設定計算時点の状態で演算した値であるため、圧延中に影響係数自体が変化してしまうことも考えられる。
【００２５】
また無張力時の圧延荷重および圧延トルクを計算する（８）式および（９）式では、圧延荷重と圧延トルクの補正を入側板厚、出側板厚および変形抵抗のみの変化を用いて行っている。一般に通常の圧延では、製品板厚精度を確保するために、ＡＧＣ（自動板厚制御）を行うため、入側板厚Ｈと出側板厚ｈはほぼ一定になる。このため変形抵抗ｋの変化の影響が大きく反映されることになる。圧延荷重Ｐと圧延トルクＧの変化は、変形抵抗ｋの変化のみならず、摩擦係数の変化や、圧延速度の変化、先進率の変化などに起因するものであり、これらの諸原因を変形抵抗ｋの変化に負わせることは、無張力時の圧延荷重Ｐ_ｉ０および圧延トルクＧ_ｉ０の推定精度に悪影響を及ぼす。とくに近年、熱間圧延でも製品表面のなめらかさの向上と圧延動力の低減を目的として、潤滑油を使用する場合が多くなっているが、これは摩擦係数を変化させて圧延荷重の急激な変動を招く原因になることがあり、その影響を低減することが必要がある。
【００２６】
本発明は上記の問題点を解決するためになされたものであり、タンデム圧延機における各スタンド間の圧延材張力の制御を、従来から行われているルーパによる張力制御を使用することなく高精度に実現し得るタンデム圧延機の張力制御装置を提供することを目的とするものである。
【００２７】
【課題を解決するための手段】
上記目的を達成するために、第１の発明は、圧延スタンド間の圧延材張力を演算する張力演算手段と、演算された圧延材張力を張力指令値に追従させるような圧延主電動機の速度指令値を演算する制御演算手段と、演算された速度指令値に追従するように圧延主電動機の速度を制御する主機速度制御手段とを備えた、圧延材を複数台の圧延スタンドに直列に通して圧延するタンデム圧延機の張力制御装置において、張力演算手段は、圧延スタンド間に設置された張力検出器の出力、圧延スタンド間に設置されたルーパ装置に取りつけられた張力検出器の出力、およびルーパを駆動する動力からの演算出力のいずれかから圧延材張力を検出し、検出された圧延材張力を張力実際値として張力制御を実施することを特徴とする。
【００２８】
第２の発明は、与えられた速度指令値に追従するように圧延主電動機の速度を制御する主機速度制御手段と、圧延スタンド出側の圧延材速度を測定する圧延材速度測定手段とを備えた、圧延材を複数台の圧延スタンドに直列に通して圧延するタンデム圧延機の張力制御装置において、ＮＯ．ｉスタンド出側の板厚を演算する出側板厚演算手段と、圧延材張力を一定に保つため、下流側のＮＯ．ｉ＋１スタンド出側で測定された圧延材速度、出側板厚演算手段で演算された当該ＮＯ．ｉスタンド出側板厚、および下流側のＮＯ．ｉ＋１スタンド出側板厚を用いて、圧延スタンド間のマスフローを一定に保つようなＮＯ．ｉスタンド出側の圧延材速度指令値を演算する圧延材速度制御手段とを備え、圧延材速度制御手段は圧延材速度指令値になるようなＮＯ．ｉスタンドの圧延主電動機の速度指令値を演算し、主機速度制御手段に与えることを特徴とする。
【００２９】
第３の発明は、圧延スタンド間の圧延材張力を演算する張力演算手段と、演算された圧延材張力を張力指令値に追従させるような圧延主電動機の速度指令値を演算する制御演算手段と、演算された速度指令値に追従するように圧延主電動機の速度を制御する主機速度制御手段と、圧延スタンド出側の圧延材速度を測定する圧延材速度測定手段とを備えた、圧延材を複数台の圧延スタンドに直列に通して圧延するタンデム圧延機の張力制御装置において、張力演算手段は、圧延材ヤング率をＥ、スタンド間距離をＬ、入側材料速度をＶ、出側材料速度をｖ、ＮＯ．ｉスタンドを示す添え字をｉ、ＮＯ．ｉ＋１スタンドを示す添え字をｉ＋１、ＮＯ．ｉスタンドとＮＯ．ｉ＋１スタンドとの間の圧延材張力をｔ_ｆｉとして、圧延材張力ｔ_ｆｉを張力発生の基本式
ｔ_ｆ１＝（Ｅ_ｉ／Ｌ_ｉ）∫（Ｖ_ｉ＋１−ｖ_ｉ）ｄｔ
によって演算するか、または、張力フィードバック係数をＫ_１０として、簡易モデル式
【数９】

によって演算することを特徴とする。
【００３０】
第４の発明は、圧延スタンド間の圧延材張力を演算する張力演算手段と、演算された圧延材張力を張力指令値に追従させるような圧延主電動機の速度指令値を演算する制御演算手段と、演算された速度指令値に追従するように圧延主電動機の速度を制御する主機速度制御手段とを備えた、圧延材を複数台の圧延スタンドに直列に通して圧延するタンデム圧延機の張力制御装置において、リアルタイムで測定することができる各圧延スタンドの圧延荷重、圧延トルク、および圧延スタンド間の圧延材張力からなる第１のデータ群と、リアルタイムで測定することができる各圧延スタンドの圧延荷重、圧延トルク、入側板厚、出側板厚、および圧延スタンド間の圧延材張力からなる第２のデータ群とのいずれか一方を用いて逐次トルクアームを同定するトルクアーム同定手段を備え、張力演算手段はトルクアーム同定手段によって同定されたトルクアーム係数あるいはトルクアームに基づいて圧延材張力を演算することを特徴とする。
【００３１】
【発明の実施の形態】
以下、図示した実施の形態に基づいて本発明をさらに詳細に説明する。
【００３２】
＜第１の実施の形態＞
図１は第１の実施の形態の構成を示す図であり、図２は同実施の形態の制御ブロック図を示すものである。
【００３３】
図１において、図１０と同一要素には同一符号を付して、それらの個々の説明は省略する。図１には、ＮＯ．ｉ−１スタンド２ａとＮＯ．ｉスタンド２ｂの間、およびＮＯ．ｉスタンド２ｂとＮＯ．ｉ＋１スタンド２ｃの間のルーパ６ａおよび６ｂも図示され、同様にルーパ電動機７ａ，７ｂ、さらにはそれぞれの張力検出器８ａ，８ｂおよび角度検出器９ａ，９ｂも示されている。角度検出器９ａ，９ｂの検出出力はルーパ角度制御手段１１ａ，１１ｂに導かれて、ルーパ電動機７ａ，７ｂを制御するために用いられる。張力演算手段１２ａ，１２ｂは、主機速度制御手段１０ａ，１０ｂおよび圧延荷重検出器４ａ，４ｂの出力に基づいて張力を推定演算するのではなく、ルーパ６ａ，６ｂに取り付けられた張力検出器８ａ，８ｂの検出出力に基づいて圧延材張力を演算するか、またはルーパ電動機７ａ，７ｂの動力すなわち電流に基づいて圧延材張力を演算する。
【００３４】
図１の張力制御装置によれば、下流側圧延スタンドに圧延材１が噛み込まれてから一定時間の後に、ルーパ６を圧延材１に接触させることができる位置まで上昇させ、ルーパ６に取り付けられた張力検出器８、またはルーパ電動機７の電流から圧延材張力を演算する。その場合、ルーパ６を上昇させる角度は、圧延材１の重量等の特性とルーパ６を駆動する能力とによって決定される。たとえば大断面積材では圧延材１の重量が大きく、ルーパ６が圧延材１から受けるトルクが大きくなり、そのためルーパ電動機７が発生すべきトルクが大きくなる。
【００３５】
一方、ルーパトルクとルーパ角度との関係は、図３に示すように、ある角度までは、トータルトルクはルーパ角度の増加に従って増加する。図３では、トータルトルクが、張力分トルク、ルーパ自重分によるトルク、圧延材重量によるトル久加速補償のためのバイアストルク、および圧延材１の折り曲げ分トルクから構成されていることを示している。
【００３６】
図３において、ルーパ６が圧延材１を持ち上げ、圧延材１に適当な張力が印加されている場合、仮にルーパ角度が２０度だったとすると、ルーパ６が発生すべきトータルトルクは、約１９０００ｋＮｍとなる。ここでルーパ角度を１０度とすると、ルーパ６が発生すべきトータルトルクは、約１２５００ｋＮｍとなる。すなわち、ルーパ角度の設定により、ルーパ６が発生すべきトルクに大小の差が生じる。圧延材１が大断面積で、ルーパトルクが大きい場合、ルーパ角度を小さくすることにより、ルーパ６が発生すべきトルクを低減することができる。
【００３７】
ルーパ角度の決定方式としては、次に圧延する材料の厚みや幅等の圧延サイズと張力設定値に基づく圧延条件により計算されるルーパ６のトータルトルクが、ルーパ電動機７が発生できる最大トルクに所定の安全率を乗じた値を超えないようなルーパ角度とする。具体的には次のようなステップの処理フローとすればよい。すなわち、
（１）計算のため、ルーパ角度の初期値を設定する。
【００３８】
（２）設定角度におけるトータルトルクを計算する。
【００３９】
（３）「トータルトルク」＜「最大トルクに安全率を乗じた値」　ならば、その設定角度を次材のルーパ角度とする。
【００４０】
（４）「トータルトルク」≧「最大トルクに安全率を乗じた値」　ならば、設定角度を減少し、（２）へ戻る。
【００４１】
上記（１）〜（４）のステップを繰り返す。ただし、ルーパ角度は下限値を設定しておくものとする。
【００４２】
図２に図１の制御装置の制御ブロック図を示す。図２において、ルーパ角度は適切な角度に制御されているものとする。張力制御手段１４では、張力演算手段１２において、ルーパ６に取り付けた張力検出器８、またはルーパ電動機７の電流から圧延材張力を演算し、この張力値が別途与えられる張力目標値に一致するように、上流側の主機速度指令値を演算する。この主機速度指令値は、主機速度制御手段１０に与えられるが、図２中では、主機速度制御手段１０、圧延主電動機５、および圧延スタンド２の総合的な応答を示す系として、主機速度制御系３として総括的に表現されている。主機速度制御系３の出力は、圧延スタンド２の圧延ロール（図示省略）の速度となり、先進率ｆを考慮して圧延材速度に変換され、ＮＯ．ｉスタンドとＮＯ．ｉ＋１スタンドの圧延材速度の差が積分され、圧延材ヤング率Ｅとスタンド間距離Ｌを考慮して、張力（張力応力）ｔが発生される。
【００４３】
なお張力演算手段１２における張力演算開始時点および制御演算手段１３の制御開始時点は、下流側圧延スタンドに圧延材１が噛み込まれた後一定の時間後とするか、または、下流側圧延スタンドに圧延材１が噛み込まれた後ルーパ制御など他の張力制御を実施してから一定の時間後とする。
【００４４】
以上述べたように本実施形態においては、従来から実施されているルーパ制御を使用しないで張力制御を行う制御方式において、下流側圧延スタンドに圧延材が噛み込まれた後一定の時間後に、ルーパ６を圧延材１に接触できる位置まで上昇させ、ルーパ６に取り付けた張力検出器８、またはルーパ６を駆動する動力から圧延材張力を演算する。その場合、ルーパ６を上昇させる角度は、圧延材１の重量等の特性とルーパ６を駆動する能力とによって決定される。
【００４５】
かくして第１の実施形態によれば、圧延材１の張力制御を行う場合、ルーパを張力検出のための手段として使用することにより、圧延材１の張力の検出を高精度に行うことができる。このとき圧延材のサイズや圧延条件に適合したルーパ角度を決定することができるため、ルーパの仕様の範囲内で安定な圧延制御を実施することができる。
【００４６】
＜第２の実施の形態＞
次に第２の実施の形態について説明する。図４は第２の実施の形態の構成を示す図である。
【００４７】
図４の装置においては、圧延スタンド２ａ，２ｂ，２ｃの出側にそれぞれ圧延材速度計１６ａ，１６ｂ，１６ｃが設置されている。この圧延材速度計としては、たとえばレーザー光ドップラー効果を利用した速度計を利用することができる。図４には、図１で図示が省略されていた圧延スタンド２ａ，２ｂ，２ｃの圧下装置１７ａ，１７ｂ，１７ｃも図示されている。圧下手段１７ａ〜１７ｃは、電動式あるいは油圧式のいずれでもよい。圧延スタンド２ａ，２ｂ，２ｃに対して出側板厚演算手段１８ａ，１８ｂ，１８ｃが設けられている。圧延スタンド２ａ，２ｂには圧延材速度制御手段１９ａ，１９ｂが設けられている。各圧延スタンドでは、自圧延スタンドの圧延荷重検出器４によって検出された圧延荷重Ｐ、自圧延スタンドの圧下手段１７によって検出された圧延ロールギャップＳ、およびミル定数Ｍに基づいて、それぞれの出側板厚ｈが演算される。
【００４８】
この実施の形態は、マスフローを一定に保つことが目的であり、そのため、各圧延スタンドの出側の板厚を演算する必要があるのである。各圧延スタンドの出側板厚ｈは、一般的に用いられているゲージメータ板厚を利用する。ゲージメータ板厚は、一般に、圧延荷重Ｐ、圧延ロールギャップＳ、およびミル定数Ｍを用いて、
ｈ＝Ｓ＋Ｐ／Ｍ　　　　　　　　　　　　　　　　　　　　…（１８）
として与えられる。
【００４９】
圧延荷重検出器４ａ〜４ｃにより各圧延スタンドごとに圧延荷重Ｐを測定し、圧下手段１７ａ〜１７ｃにより測定した圧延ロールギャップＳを元に、各圧延スタンド出側の板厚ｈの演算を出側板厚演算手段１８ａ〜１８ｃで行う。なお、圧延スタンドの出側にＸ線等を用いた板厚計が設置される場合もあり、その場合は板厚計の検出による出側板厚を利用してもよい。
【００５０】
圧延スタンド２ａ，２ｂに対して設けられている圧延材速度制御手段１９ａ，１９ｂでは、以下の演算を行う。ＮＯ．ｉスタンドとＮＯ．ｉ＋１スタンド間のマスフローが一定に保たれる場合は、板幅の変化が小さいと仮定すると、材料速度をｖとして、ほぼ、
ｈ_ｉ＋１・ｖ_ｉ＋１＝ｈ_ｉ・ｖ_ｉ　　　　　　　　　　　　…（１９）
が成立する。
【００５１】
圧延材速度指令値Ｖ_Ｒｉ ^ＲＥＦは、（１９）式を用いて、
ｖ_ｉ ^ＲＥＦ＝（ｈ_ｉ＋１／ｈ_ｉ）ｖ_ｉ＋１ ^ＡＣＴ　　　　　　　…（２０）
で表される。ここで、ｈ_ｉ，ｈ_ｉ＋１はそれぞれ出側板厚演算手段１８ｂ，１８ｃで演算された圧延スタンド２ｂ，２ｃの出側の板厚であり、ｖ_ｉ＋１ ^ＡＣＴは圧延材速度計１６ｃで測定された圧延スタンド２ｃ出側の圧延材速度実績値である。したがって、圧延材速度実績値ｖ_ｉ ^ＡＣＴが圧延材速度指令値ｖ_ｉ ^ＲＥＦとなるような主機速度指令値を主機速度制御手段１０ｂに与えることにより、マスフロー一定の条件である（１９）式を実現することができる。
【００５２】
図５は図４の制御装置の制御ブロック図を示すものである。図５における張力制御手段２０の中で上記の制御演算が実行される。
【００５３】
圧延材速度計１６ａ〜１６ｃにおいては、上記のようにレーザー等の波動を使用したドップラー効果による速度計などを用いて直接圧延材速度を測定するほか、モデル式により先進率ｆを演算し、先進率ｆと圧延ロール周速Ｖ_Ｒから圧延材速度ｖを計算する方法もある。先進率ｆを用いて圧延材速度ｖを計算すれば、速度計が故障した場合のバックアップとして使用できるほか、速度計のノイズ除去のフィルターとしても使用できる。
【００５４】
まず先進率ｆのモデル式は、例えば、
ｆ＝ａｒ^ｂ　　　　　　　　　　　　　　　　　　　　　　…（２１）
と表される。ここで、ａ，ｂは係数、ｒは圧下率であり、圧下率ｒは圧延スタンドの入側板厚Ｈおよび出側板厚ｈを用いて、
ｒ＝（Ｈ−ｈ）／Ｈ　　　　　　　　　　　　　　　　　　…（２２）
と表される。
【００５５】
圧延材の速度ｖと圧延ロールの周速Ｖ_Ｒの関係は、
ｖ＝（１＋ｆ）Ｖ_Ｒ　　　　　　　　　　　　　　　　　　…（２３）
で表される。
【００５６】
モデル式により先進率ｆを演算する場合、モデル式の精度が重要であり、上記係数ａ，ｂを精度良く同定することが必要となる。同定のための回帰式は、
ｙ＝ｃｘ＋ｄ　　　　　　　　　　　　　　　　　　　　　…（２４　）
ｙ＝ｌｎ（ｖ／Ｖ_Ｒ−１），ｘ＝ｌｎ（ｒ），ｄ＝ｌｎ（ａ）
で表される。
【００５７】
回帰式により係数ｃとｄを同定することにより、次の、
ｃ＝ｌｎ（ａ），ｂ＝ｄ　　　　　　　　　　　　　　　　　…（２５）
により、（２１）式の係数ａ，ｂを求めることができる。なお回帰は、逐次最小二乗法や一括してデータを扱う一般の最小二乗法などを適用して求めることができる。
【００５８】
このようにして求めた先進率モデル式（２１）式のパラメータを、圧延材の特性により区分して計算機内パラメータテーブルに格納し、速度計１６が故障等で使用できない状態において、類似の特性をもつ圧延材に対してパラメータテーブルからパラメータを取り出して先進率ｆを計算し、その先進率ｆと圧延ロール周速Ｖ_Ｒから（２３）式により演算した圧延材速度の計算値を圧延材速度ｖとして使用する。これにより、速度計が使用できない場合でも上記の制御方式を継続することができる。
【００５９】
また先進率モデル式のパラメータを、圧延材の特性により区分して計算機内パラメータテーブルに格納し、速度計が故障等で使用できない状態において、類似の特性をもつ圧延材に対してパラメータテーブルからパラメータを取り出して先進率を計算しその先進率と圧延ロール周速から演算した圧延材速度計算値と、速度計で測定した圧延材速度実績値を比較して、その差が所定の閾値を超える場合に圧延材速度として圧延材速度計算値を使用する。これにより速度計に大きなノイズが乗った場合、その値を取り込んで制御に対し外乱となる事態を防ぐことができる。
【００６０】
なお、図５に示す方式では、張力が確立した後のマスフローを一定に保つことは可能であるが、張力の初期状態を形成する必要がある。このため、下流側圧延スタンドに圧延材が噛み込まれた後、張力を確立させるために、ルーパ制御を実施するか、あるいは図１および図２の発明を実施する。
【００６１】
本実施の形態によれば、圧延スタンド間の圧延材速度を測定する圧延材速度計が存在する場合、マスフローを常に一定に保つことにより、安定な張力制御を行うことができる。また圧延材速度計が故障などにより使用できない場合は、同定した先進率モデルを用いて高精度に圧延材速度を演算し、マスフローを一定に保つことができる。
【００６２】
＜第３の実施の形態＞
次に第３の実施の形態について説明する。図６は第３の発明の実施の形態の構成を示す図である。
【００６３】
図６において、各圧延スタンド２ａ，２ｂ，２ｃの出側には、圧延材速度計１６ａ，１６ｂ，１６ｃが設置されている。圧下手段１７ａ，１７ｂ，１７ｃにより測定された各圧延スタンドの圧延ロールギャップＳを元に、各圧延スタンド出側の板厚を予測することができ、出側板厚の演算を出側板厚演算手段１８ａ〜１８ｃで行う。
【００６４】
張力制御手段２１において、圧延材１の張力を制御する場合、出側板厚演算手段１８による各スタンド出側板厚ｈを計算し、これと圧延材速度ｖを用いて、張力演算手段１２ａ，１２ｂによって出側圧延材の張力を演算し、制御演算手段１３ａ，１３ｂにおいて張力目標値との偏差を小さくするような主機速度指令値を主機速度制御手段１０ａ，１０ｂに出力する。張力演算手段１２における張力演算は、張力発生の基本式である（１６）式に基づいて行われる。
【００６５】
ＮＯ．ｉ＋１スタンドの入側材料速度Ｖ_ｉ＋１を直接測定することはできないので、後進率ｂおよびロール周速Ｖ_Ｒを用いて、
Ｖ_ｉ＋１＝（１−ｂ_ｉ＋１）Ｖ_Ｒｉ＋１
＝（１＋ｆ_ｉ＋１）（ｈ_ｉ＋１／Ｈ_ｉ＋１）Ｖ_Ｒｉ＋１
＝（ｈ_ｉ＋１／Ｈ_ｉ＋１）ｖ_ｉ＋１　　　　　　　　　…（２６）
で計算する。
【００６６】
圧延材ヤング率Ｅと張力フィードバック係数は、圧延材特性の区分によるパラメータテーブルを持つ。また、張力演算手段１２における張力演算は、張力発生の基本式である（１６）式から導いた簡易モデル式である（１７）式を用いて行う。
【００６７】
なお圧延材速度は、第２の実施形態で説明したと同様に、速度計などを用いて直接圧延材速度を測定した結果を使用できるほか、先進率を演算し、先進率と圧延ロール周速から圧延材速度を計算する方法もあり得る。
【００６８】
図７は図６の制御装置の制御ブロック図を示すものである。張力演算手段１２ａ，１２ｂにおいては、上記（１６）式の方式を使用して圧延材張力ｔ_ｆｉを求め、その圧延材張力を張力指令値に追従させるような圧延主電動機の速度指令値を制御演算手段１３で演算し、その速度指令値に追従するように主機速度制御手段１０によって圧延主電動機５の速度を制御する。
【００６９】
図８も第３の実施形態に係わる制御ブロック図であり、張力演算手段１２においては、上記（１７）式の方式を使用して圧延材張力ｔ_ｆｉを演算する。
【００７０】
かくして第３の実施形態によれば、圧延スタンド間の圧延材速度を測定する速度計が存在する場合、張力発生のモデル式により高精度に圧延材の張力を演算することにより安定な張力制御を実施することができる。速度計が交渉などにより使用できない場合でも、同定した先進率モデルにより、高精度に圧延材速度を演算し、安定した張力制御を続行することができる。
【００７１】
＜第４の実施の形態＞
次に第４の実施の形態について説明する。図９は第４の実施の形態の構成を示す図である。
【００７２】
図９の張力制御手段２３はトルクアーム同定手段２２を含んでいる。トルクアーム同定手段２２は、リアルタイムで測定することができる各圧延スタンドの圧延荷重Ｐ、圧延トルクＧ、および圧延スタンド間の圧延材張力ｔ_ｆを用いて、逐次トルクアーム係数を同定し、あるいはリアルタイムで測定することができる各圧延スタンドの圧延荷重Ｐ、圧延トルクＧ、入側板厚Ｈ、出側板厚ｈ、および圧延スタンド間の圧延材張力ｔ_ｆを用いて、逐次トルクアームを同定し、このトルクアーム係数あるいはトルクアームに基づいて、張力演算手段１２ａ，１２ｂにおいて圧延材張力を演算する。
【００７３】
詳細には、トルクアーム同定手段２２は以下の演算を行う。
【００７４】
まずトルクアーム係数を同定する場合を示す。基本式である（１），（２），（３）式のほかに、
Ａ＝２ａＬ_ｄ　　　　　　　　　　　　　　　　　　　　　…（２７）
を考慮する。ここで、Ａはトルクアーム、ａはトルクアーム係数、Ｌ_ｄは投影接触弧長である。
【００７５】
（１）式および（２）式の中の影響係数のうち、γ，δは以下のように表現することができる。すなわち、
γ_ｉ＝Ａ_Ｒｉ・Ｒ_ｉ　　　　　　　　　　　　　　　　　　…（２８）
δ_ｉ＝Ａ_Ｒｉ−１・Ｒ_ｉ　　　　　　　　　　　　　　　　…（２９）
ここで、Ａ_Ｒは圧延材出側断面積、Ｒは圧延ロール半径である。
【００７６】
ＮＯ．ｉ−１スタンド２ａからＮＯ．ｉ＋１スタンド２ｃまでを考えてみる。（１）〜（３）式から、
Ｇ_ｉ−１＝Ａ_ｉ−１Ｐ_ｉ−１−Ａ_Ｒｉ−１Ｒ_ｉ−１ｔ_ｆｉ−１
＋Ａ_Ｒｉ−２Ｒ_ｉ−１ｔ_ｆｉ−２　　　　　　　　…（３０）
Ｇ_ｉ＝Ａ_ｉＰ_ｉ−Ａ_ＲｉＲ_ｉｔ_ｆｉ
＋Ａ_Ｒｉ−１Ｒ_ｉｔ_ｆｉ−１　　　　　　　　　　　　…（３１）
Ｇ_ｉ＋１＝Ａ_ｉ＋１Ｐ_ｉ＋１−Ａ_Ｒｉ＋１Ｒ_ｉ＋１ｔ_ｆｉ＋１
＋Ａ_ＲｉＲ_ｉ＋１ｔ_ｆｉ　　　　　　　　　　　　　…（３２）
ここで、ＮＯ．ｉ＋１〜ＮＯ．ｉ＋２スタンド間の張力は既知であり（ルーパ制御実施などで正確に測定できると仮定）、ＮＯ．ｉ−２スタンドより上流の張力は０であるとする。（３０）〜（３２）式の両辺を、それぞれロール半径Ｒで規格化すると、
【数１０】

となる。
【００７７】
（３３）〜（３５）式の左辺どうし、および右辺どうしをそれぞれ加算して、
【数１１】

を得る。ここで、（２７）式を適用して、
【数１２】

トルクアーム係数ａを求めるために、回帰式を、
【数１３】

と定義する。
【００７８】
圧延荷重、圧延トルク、入出側板厚、張力等の実績値から、上記回帰式に基づき、逐次最小２乗法を適用して、トルクアーム係数を計算する。
【００７９】
次にトルクアームを同定する場合を示す。（３６）式までは同様の計算を行うが、（３７）式は使用せず、トルクアームＡを、
【数１４】

として同定する。
【００８０】
次に同定したトルクアーム係数から、張力を演算する。（２７）式、（３３）式、（３４）式、および（３５）式から、
【数１５】

となり、スタンド間の材料張力ｔ_ｆを計算することができる。
【００８１】
同定したトルクアームＡの場合も同様に張力ｔ_ｆを求めることができる。
【００８２】
なお上記では２つの圧延スタンド間の張力を求めるために３つの圧延スタンドのトルクアームの関係式を考えたが、当然のことながら、２つの圧延スタンド間、あるいは４つ以上の圧延スタンド間にも容易に適用することができる。
【００８３】
制御演算手段１３において、得られた圧延材張力を張力指令値に追従させるような圧延主電動機５の速度指令値を演算し、主機速度制御手段１０においてその速度指令値に追従するように圧延主電動機５の速度を制御する。
【００８４】
かくして第４の実施形態によれば、トルクアーム係数あるいはトルクアームＡのリアルタイムの変化を精度良く演算し、圧延中の状態の変化を捉えて、張力ヘの影響を的確に考慮することができる。
【００８５】
【発明の効果】
本発明によれば、ルーパ制御を使用しない場合の張力推定精度を向上させ、それにより張力制御性能を向上させ、さらに安定な操業と製品の高品質化を達成することができる。
【図面の簡単な説明】
【図１】本発明による張力制御装置の第１の実施の形態を示す機能ブロック図。
【図２】図１の張力制御装置の制御ブロック図。
【図３】第１の実施の形態に関連してルーパにかかるトルクを説明するための説明図。
【図４】本発明による張力制御装置の第２の実施の形態を示す機能ブロック図。
【図５】図４の張力制御装置の制御ブロック図。
【図６】本発明による張力制御装置の第３の実施の形態を示す機能ブロック図。
【図７】図６の張力制御装置の制御ブロック図。
【図８】本発明による張力制御装置の第３の実施の形態を示す制御ブロック図。
【図９】本発明による張力制御装置の第４の実施の形態を示す機能ブロック図。
【図１０】従来の張力制御装置の全体構成を示す図。
【図１１】従来の張力制御装置の概念を説明するための説明図。
【符号の説明】
１　圧延材
２　圧延スタンド
３　主機速度制御系
４　圧延荷重検出器（Ｌ／Ｃ）
５　圧延主電動機
６　ルーパ
７　ルーパ電動機
８　張力検出器
９　角度検出器
１０　主機速度制御手段
１１　ルーパ角度制御手段
１２　張力演算手段
１３　制御演算手段
１４　張力制御手段
１５　ルーパ制御手段
１６　圧延材速度計
１７　圧下手段
１８　出側板厚演算手段
１９　圧延材速度制御手段
２０　張力制御手段
２１　張力制御手段
２２　トルクアーム同定手段
２３　張力制御手段
２４　張力制御手段[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tension control device for a tandem rolling mill that controls a rolled material tension without using looper control.
[0002]
[Prior art]
Sheet thickness and sheet width are used as indices indicating the quality of the final product in hot rolling or cold rolling. Of these indices, automatic thickness control (AGC) is performed on the thickness, and automatic width control is performed on the width. On the other hand, the tension applied to the material during rolling not only affects the sheet thickness and the sheet width, which are quality indicators, but also a well-controlled tension contributes to a stable operation. Therefore, tension control is generally performed.
[0003]
In particular, the rolled material in hot rolling is heated to a high temperature due to heat treatment, and the deformation resistance of the rolled material is reduced. If the tension is large, the material is easily broken. If the tension is set low to prevent this breakage, it may be in a tensionless state due to disturbance or erroneous setting, and if the tensionless state continues, a large loop will occur between the rolling stands and cause an accident Sometimes. Therefore, in a hot rolling mill, a looper device is particularly provided between the rolling stands, and the tension control is performed by the looper device, and the height of the looper is controlled from the viewpoint of improving the material passing property.
[0004]
However, a large-capacity looper drive motor is required to support a rolled material with a large cross-sectional area, but various sensors are installed between the rolling stands where the motors that drive the looper are installed. In some cases, a sufficient space for the looper drive motor cannot be secured. Large capacity motors are also expensive.
[0005]
For this reason, the capacity of the looper motor is made as small as possible, high-performance tension control using a looper is performed on rolled material with a small cross-sectional area, and tension control without using a looper is performed on rolled material with a large cross-sectional area. In many cases, so-called looperless control is performed.
[0006]
FIG. 10 shows a rolling control device provided with a conventional general tension control means 24. In FIG. 10, the rolled material 1 has the upstream NO. i-1. i rolling stand 2b, NO. i + 1 rolling stand 2c, NO. It is sent to i + 2 rolling stand 2d and rolled. Here, assuming that the total number of stands of the tandem rolling mill is n, n = 5 to 7 is general, but only four stands are illustrated in the drawing. The tension control can be performed between the stands. However, if the state between the four stands i-1 to i + 2 is considered, the tension can be easily extended to all the n stands. Consider only state. Note that i is in the range of 2 ≦ i ≦ n−2. Further, in the control device described below, reference numerals indicating elements are represented by a combination of numbers and alphabets, but the numbers represent the types of the elements, and the letters a to d correspond to the alphabets of the rolling stands. It belongs to whether it belongs to. Also, it should be noted that the alphabet may be omitted and only the numeral may be used as a generic term for the elements belonging to each rolling stand. Further, in FIG. 10, illustration of a rolling-down device provided in each rolling stand is omitted.
[0007]
Rolling load detectors 4a, 4b, 4c such as load cells (L / C) are installed in the rolling stands 2a, 2b, 2c, respectively, and the rolling load is detected for each rolling stand. The speeds of the rolling main motors (main machines M) 5a, 5b, 5c that drive the rolling rolls of each rolling stand are controlled by main machine speed control means 10a, 10b, 10c, respectively.
[0008]
A looper may be provided between the stands, and FIG. i + 1 rolling stand 2c and NO. Only the looper 6c provided between the i + 2 rolling stands 2d is illustrated. i-1 rolling stand 2a and NO. i between the rolling stands 2b and NO. i rolling stand 2b and NO. The loopers provided between the i + 1 rolling stands 2c are not shown. The looper 6c is vertically driven by a looper motor (M) 7c, and the looper motor 7c is provided with a looper angle detector 9c for detecting the angle of the looper arm from its height. Here, an electric motor (electric motor) is shown as a driving means for driving the looper 6c, but this can be replaced by a hydraulic motor or a pneumatic motor.
[0009]
In the tension control using the looper, the looper angle is controlled by the looper control means 15c via the looper motor 7c using the looper angle detected by the angle detector 9c and the tension detected by the tension detector 8c. The correction value for the main engine set speed is given from the looper control unit 15c to the main engine speed control unit 10c. Thereby, NO. i + 1 rolling stand 2c and NO. The tension of the rolled material 1 and the looper angle between the i + 2 rolling stand 2d are controlled.
[0010]
When controlling the tension of the rolled material 1, the tension calculation means 12a and 12b determine the rolling stand based on the rolling load detected by the rolling load detectors 4a and 4b and the rolling torque calculated by the main engine speed control means 10a and 10b. And the control calculation means 13a and 13b calculate a speed correction value to reduce the deviation from the tension target value, thereby correcting an externally applied set speed and controlling the main engine speed control. A speed command is given to the means 10a and 10b.
[0011]
The rolling torque used for the tension calculation is not the torque itself generated by the main engine 5, but the load torque obtained by removing the acceleration / deceleration torque from the generated torque, that is, the total torque and subtracting the loss torque related to the rotation speed. I do.
[0012]
In the tension control using the looper, the tension can be calculated from the load received by the load cell attached to the looper, or the tension can be accurately calculated using the load torque of the looper driving device. In the looperless control, since there is no member that comes into contact with the rolled material between the stands, the rolling load and rolling torque of the rolling stand are used to estimate the rolled material tension. This estimation is performed as follows.
[0013]
First, the basic expressions are the following three expressions. That is,
P_i= P_i0−α_i・ T_i−β_i・ T_i-1… (1)
G_i= G_i0−γ_i・ T_i+ Δ_i・ T_i-1… (2)
G_i0= A_i0・ P_i0… (3)
here,
i: Stand number
P: Rolling load
G: Rolling torque
A: Torque arm
α: Influence coefficient from forward tension to rolling load (∂P_i/ ∂t_i)
β: Coefficient of influence from back tension to rolling load (∂P_i/ ∂t_i-1)
γ: Coefficient of influence from forward tension to rolling torque (∂G_i/ ∂t_i)
δ: Coefficient of influence from back tension to rolling torque (ΔG_i/ ∂t_i-1)
In each equation, the suffix 0 indicates the absence of tension.
[0014]
The expression (1) means that the rolling load is reduced when the front tension or the rear tension is applied, and the expression (2) means that the rolling torque is reduced when the front tension is applied. It means that the rolling torque increases if the back tension is applied.
[0015]
The rolling load and rolling torque at the time of no tension are locked on before the tension is applied, and are corrected by the following method after the tension is applied (the corrected value P₀ ^M, G₀ ^M) Is common.
[0016]
Estimation of load and torque at the time of no tension that changes during rolling is
(Equation 2)

Done by Here, H is the stand-in thickness (stand-in side plate thickness), h is the stand-out thickness (stand-out side plate thickness), b is the plate width, and k is the deformation resistance.
[0017]
The influence coefficient vector for the rolling torque is
(Equation 3)

And the influence coefficient vector for the rolling load is
(Equation 4)

And the vector X from the lock-on value_iThe deviation of
(Equation 5)

And Where H_i0, H_i0, B_i0, K_i0Are lock-on (memory) values, respectively. In general, a change in the plate width is small and is often excluded from consideration.
[0018]
The rolling load and rolling torque in the zero tension state at lock-on are P_i0And G_i0And these values are corrected according to the change in the rolling condition, and the rolling load P during rolling is corrected._i0 ^MAnd rolling torque G_i0 ^MTo
P_i0 ^M= P_i0+ Z_i・ △ X_i… (8)
G_i0 ^M= G_i0+ Y_i・ △ X_i… (9)
Is estimated as
[0019]
Thus, equations (1), (2) and (3) are
P_i= P_i0 ^M−α_i・ T_i−β_i・ T_i-1… (10)
G_i= G_i0 ^M−γ_i・ T_i+ Δ_i・ T_i-1… (11)
G_i0 ^M= A_i0 ^M・ P_i0 ^M… (12)
Will be modified as follows.
[0020]
From equations (10), (11) and (12), the following equation is obtained as an equation for estimating the tension. That is,
・ Backward tension t_i-1From the forward tension t_iAs an equation for estimating
(Equation 6)

・ Forward tension t_iFrom the rear tension t_i-1As an equation for estimating
(Equation 7)

NO. i stand 2b and NO. Between the i-1 stands 2a,
(Equation 8)

From the equation (13), the forward tension can be estimated using the rolling load, the rolling torque, and the backward tension. This is applicable when the back tension can be measured. Similarly, the backward tension can be estimated from the equations (14) and (15) using the rolling load, the rolling torque, and the forward tension. This is applicable when forward tension can be measured.
[0021]
The concept of tension estimation in looperless control will be described with reference to FIG. During rolling, the rolling load P under tension is applied._iAnd rolling torque G_iCan be measured only, but the rolling load P at no tension before point A of i + 1 stand-on_i0And rolling torque G_i0Is stored, and the tension is estimated by an arithmetic expression using the influence coefficient using the change ΔR after the point A of the i + 1 stand-on.
[0022]
On the other hand, Japanese Patent Publication No. 2-14124 discloses a method of estimating the tension between stands of a rolled material by calculating a torque arm by an online least squares method. However, this method is based on the assumption that the tension calculation between all the stands is performed in order to eliminate the tension term included in the basic expression representing the rolling state, and cannot be applied when partial application is desired. .
[0023]
[Problems to be solved by the invention]
In the above-mentioned looperless tension estimation method, forward tension or backward tension is required in addition to the rolling load and the rolling torque. For example, when the looperless control is continuously performed, the front tension or the rear tension is an estimated value, and further estimating the tension based on the estimated value may cause deterioration of the estimation accuracy.
[0024]
When looperless control is performed between consecutive stands, since rear tension has already been generated between the stands on the downstream side, the rolling load and rolling torque in the non-tension state cannot be actually measured, and the influence coefficient is reduced. It must be used to estimate the rolling load and rolling torque under no tension. At this time, the estimated value of the tension from the rolling load and the rolling torque in the non-tension state includes an error due to the influence coefficient and the estimated tension value. For this reason, the accuracy of tension estimation decreases as going downstream. Further, since the influence coefficient is generally a value calculated in the state at the time of the setting calculation at the leading end of the rolled material, the influence coefficient itself may change during rolling.
[0025]
In the equations (8) and (9) for calculating the rolling load and the rolling torque under no tension, the correction of the rolling load and the rolling torque is performed by using only the change in the input side plate thickness, the output side plate thickness and the deformation resistance. I have. Generally, in normal rolling, in order to secure product thickness accuracy, AGC (automatic thickness control) is performed, so that the incoming side thickness H and the outgoing side thickness h are substantially constant. Therefore, the influence of the change in the deformation resistance k is largely reflected. The changes in the rolling load P and the rolling torque G are caused not only by the change in the deformation resistance k, but also by the change in the friction coefficient, the change in the rolling speed, the change in the advance rate, and the like. The change in k is caused by the rolling load P under no tension._i0And rolling torque G_i0Has an adverse effect on the estimation accuracy. Particularly in recent years, lubricating oil has been increasingly used in hot rolling for the purpose of improving the smoothness of the product surface and reducing the rolling power. It is necessary to reduce the influence.
[0026]
The present invention has been made in order to solve the above-mentioned problems, and the control of the rolled material tension between the stands in a tandem rolling mill can be performed with high precision without using a conventionally performed tension control with a looper. It is an object of the present invention to provide a tension control device for a tandem rolling mill that can be realized in the following manner.
[0027]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention provides a tension calculating means for calculating a rolled material tension between rolling stands, and a speed command of a main rolling motor for causing the calculated rolled material tension to follow a tension command value. Control operation means for calculating the value, and main machine speed control means for controlling the speed of the rolling main motor so as to follow the calculated speed command value, passing the rolled material in series through a plurality of rolling stands In the tension control device of the tandem rolling mill for rolling, the tension calculation means includes an output of a tension detector installed between the rolling stands, an output of a tension detector attached to a looper device installed between the rolling stands, and a looper. Is characterized in that the rolled material tension is detected from any of the calculation outputs from the power for driving the rolled material, and the detected rolled material tension is used as the actual tension value to perform the tension control.
[0028]
The second invention comprises a main machine speed control means for controlling the speed of the rolling main motor so as to follow a given speed command value, and a rolled material speed measuring means for measuring the rolled material speed on the exit side of the rolling stand. Further, in a tension control device of a tandem rolling mill for rolling a rolled material by passing it through a plurality of rolling stands in series, NO. An outlet side thickness calculating means for calculating the thickness of the outlet side of the stand and a downstream NO. i + 1 The rolled material speed measured at the outlet side of the stand and the NO. i. stand outlet side plate thickness and downstream NO. Using the sheet thickness on the outlet side of the i + 1 stand, the NO. and a rolled material speed control means for calculating a rolled material speed command value on the exit side of the i-stand. It is characterized in that a speed command value of the rolling main motor of the i-stand is calculated and given to the main machine speed control means.
[0029]
According to a third aspect of the present invention, there is provided a tension calculating means for calculating a rolled material tension between rolling stands, and a control calculating means for calculating a speed command value of a main rolling motor for causing the calculated rolled material tension to follow the tension command value. A main rolling stock speed control means for controlling the speed of the rolling main motor so as to follow the calculated speed command value, and a rolling material speed measuring means for measuring the rolling material speed on the exit side of the rolling stand, In a tension control device of a tandem rolling mill that performs rolling by passing through a plurality of rolling stands in series, a tension calculating means includes a rolled material Young's modulus E, a stand-to-stand distance L, an incoming material speed V, an outgoing material speed. To v, NO. The suffix indicating the i-stand is i, NO. The suffix indicating the i + 1 stand is i + 1, NO. i stand and NO. The rolled material tension between the i + 1 stand and t_fiThe rolled material tension t_fiThe basic formula of tension generation
t_f1= (E_i/ L_i) ∫ (V_{i + 1}-V_i) Dt
Or the tension feedback coefficient is K₁₀As a simple model formula
(Equation 9)

The calculation is performed by
[0030]
According to a fourth aspect of the present invention, there is provided a tension calculating means for calculating a rolled material tension between rolling stands, and a control calculating means for calculating a speed command value of a main rolling motor to cause the calculated rolled material tension to follow the tension command value. Main machine speed control means for controlling the speed of the rolling main motor so as to follow the calculated speed command value, and tension control of a tandem rolling mill for rolling a rolled material in series through a plurality of rolling stands. In the apparatus, a first data group consisting of a rolling load of each rolling stand, a rolling torque and a rolling material tension between rolling stands that can be measured in real time, and a rolling load of each rolling stand that can be measured in real time , The rolling torque, the incoming side plate thickness, the outgoing side plate thickness, and the second data group consisting of the rolled material tension between rolling stands. Comprising a torque arm identification means, the tension calculating means is characterized by calculating a rolling material tension based on the torque arm coefficient or torque arm identified by the torque arm identification means.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail based on the illustrated embodiments.
[0032]
<First embodiment>
FIG. 1 is a diagram showing the configuration of the first embodiment, and FIG. 2 is a control block diagram of the first embodiment.
[0033]
1, the same elements as those in FIG. 10 are denoted by the same reference numerals, and the description thereof will be omitted. FIG. i-1 stand 2a and NO. i stand 2b and NO. i stand 2b and NO. Loopers 6a and 6b between the i + 1 stand 2c are also shown, as well as looper motors 7a and 7b, as well as respective tension detectors 8a and 8b and angle detectors 9a and 9b. The detection outputs of the angle detectors 9a and 9b are guided to looper angle control means 11a and 11b and used to control the looper motors 7a and 7b. The tension calculators 12a and 12b do not estimate and calculate the tension based on the outputs of the main engine speed controllers 10a and 10b and the rolling load detectors 4a and 4b. Instead, the tension detectors 8a and The rolled material tension is calculated based on the detection output of 8b, or the rolled material tension is calculated based on the power of the looper motors 7a and 7b, that is, the current.
[0034]
According to the tension control device of FIG. 1, after a certain period of time after the rolled material 1 is caught in the downstream rolling stand, the looper 6 is raised to a position where it can contact the rolled material 1 and attached to the looper 6. The rolled material tension is calculated from the detected current of the tension detector 8 or the looper motor 7. In this case, the angle at which the looper 6 is raised is determined by characteristics such as the weight of the rolled material 1 and the ability to drive the looper 6. For example, in the case of a large cross-section material, the weight of the rolled material 1 is large, and the torque that the looper 6 receives from the rolled material 1 increases, so that the torque to be generated by the looper motor 7 increases.
[0035]
On the other hand, as shown in FIG. 3, the relationship between the looper torque and the looper angle is such that, up to a certain angle, the total torque increases as the looper angle increases. FIG. 3 shows that the total torque is constituted by the tension torque, the torque by the looper's own weight, the bias torque for torque acceleration compensation by the rolled material weight, and the bending torque of the rolled material 1. .
[0036]
In FIG. 3, when the looper 6 lifts the rolled material 1 and an appropriate tension is applied to the rolled material 1, assuming that the looper angle is 20 degrees, the total torque to be generated by the looper 6 is about 19000 kNm. Become. Assuming that the looper angle is 10 degrees, the total torque to be generated by the looper 6 is about 12,500 kNm. That is, the setting of the looper angle causes a difference in the magnitude of the torque to be generated by the looper 6. When the rolled material 1 has a large cross-sectional area and a large looper torque, the torque to be generated by the looper 6 can be reduced by reducing the looper angle.
[0037]
As a method for determining the looper angle, the total torque of the looper 6 calculated by the rolling conditions based on the rolling size such as the thickness and width of the material to be rolled next and the tension set value is determined as the maximum torque that the looper motor 7 can generate. The looper angle should not exceed the value multiplied by the safety factor. Specifically, the processing flow of the following steps may be used. That is,
(1) An initial value of the looper angle is set for calculation.
[0038]
(2) Calculate the total torque at the set angle.
[0039]
(3) If “total torque” <“value obtained by multiplying the maximum torque by the safety factor”, the set angle is set as the looper angle of the next material.
[0040]
(4) If “total torque” ≧ “the value obtained by multiplying the maximum torque by the safety factor”, the set angle is reduced, and the process returns to (2).
[0041]
Steps (1) to (4) are repeated. However, a lower limit value is set for the looper angle.
[0042]
FIG. 2 shows a control block diagram of the control device of FIG. In FIG. 2, it is assumed that the looper angle is controlled to an appropriate angle. In the tension control means 14, the tension calculating means 12 calculates the rolled material tension from the current of the tension detector 8 attached to the looper 6 or the current of the looper electric motor 7, so that the tension value matches the separately given tension target value. Then, the main engine speed command value on the upstream side is calculated. This main machine speed command value is given to main machine speed control means 10. In FIG. 2, the main machine speed control means 10, rolling main motor 5, and rolling stand 2 are used as a system indicating the overall response. This is generally expressed as system 3. The output of the main machine speed control system 3 is the speed of a rolling roll (not shown) of the rolling stand 2 and is converted into a rolled material speed in consideration of the advance rate f. i stand and NO. The difference between the rolled material speeds of the (i + 1) th stand is integrated, and a tension (tensile stress) t is generated in consideration of the rolled material Young's modulus E and the stand-to-stand distance L.
[0043]
Note that the tension calculation start time of the tension calculation means 12 and the control start time of the control calculation means 13 are set at a certain time after the rolled material 1 has been caught in the downstream rolling stand, or at the downstream rolling stand. After the rolled material 1 has been bitten, a certain period of time has elapsed after performing other tension control such as looper control.
[0044]
As described above, in the present embodiment, in the control method of performing tension control without using the looper control which has been conventionally performed, the looper is controlled after a certain time after the rolled material is caught in the downstream rolling stand. 6 is raised to a position where it can come into contact with the rolled material 1, and the rolled material tension is calculated from the tension detector 8 attached to the looper 6 or the power for driving the looper 6. In this case, the angle at which the looper 6 is raised is determined by characteristics such as the weight of the rolled material 1 and the ability to drive the looper 6.
[0045]
Thus, according to the first embodiment, when controlling the tension of the rolled material 1, the tension of the rolled material 1 can be detected with high accuracy by using the looper as a means for detecting the tension. At this time, since the looper angle suitable for the size of the rolled material and the rolling conditions can be determined, stable rolling control can be performed within the range of the specifications of the looper.
[0046]
<Second embodiment>
Next, a second embodiment will be described. FIG. 4 is a diagram showing the configuration of the second embodiment.
[0047]
In the apparatus of FIG. 4, rolling material speedometers 16a, 16b, and 16c are installed on the exit sides of the rolling stands 2a, 2b, and 2c, respectively. As this rolled material speedometer, for example, a speedometer utilizing the laser light Doppler effect can be used. FIG. 4 also shows the rolling-down devices 17a, 17b, 17c of the rolling stands 2a, 2b, 2c, which are not shown in FIG. The rolling-down means 17a to 17c may be either electric or hydraulic. Discharge side thickness calculating means 18a, 18b, 18c are provided for the rolling stands 2a, 2b, 2c. The rolling stands 2a and 2b are provided with rolled material speed control means 19a and 19b. In each rolling stand, based on the rolling load P detected by the rolling load detector 4 of the rolling stand, the rolling roll gap S detected by the rolling-down means 17 of the rolling stand, and the mill constant M, The thickness h is calculated.
[0048]
The purpose of this embodiment is to keep the mass flow constant, and therefore, it is necessary to calculate the thickness of the exit side of each rolling stand. The thickness h of the delivery side of each rolling stand uses a gauge meter thickness generally used. The gauge meter plate thickness is generally calculated using a rolling load P, a rolling roll gap S, and a mill constant M.
h = S + P / M (18)
Given as
[0049]
The rolling load P is measured for each rolling stand by the rolling load detectors 4a to 4c, and based on the rolling roll gap S measured by the rolling-down means 17a to 17c, the calculation of the thickness h at the outlet of each rolling stand is performed on the delivery plate. This is performed by the thickness calculating means 18a to 18c. In addition, a thickness gauge using X-rays or the like may be installed on the exit side of the rolling stand. In this case, the exit thickness obtained by detection of the thickness gauge may be used.
[0050]
In the rolling material speed control means 19a, 19b provided for the rolling stands 2a, 2b, the following calculation is performed. NO. i stand and NO. If the mass flow between the (i + 1) -th stands is kept constant, assuming that the change in the plate width is small, assuming that the material speed is v and
h_{i + 1}・ V_{i + 1}= H_i・ V_i… (19)
Holds.
[0051]
Rolled material speed command value V_Ri ^REFIs calculated by using equation (19).
v_i ^REF= (H_{i + 1}/ H_i) V_{i + 1} ^ACT… (20)
Is represented by Where h_i, H_{i + 1}Is the sheet thickness on the output side of the rolling stands 2b, 2c calculated by the output side sheet thickness calculating means 18b, 18c, respectively._{i + 1} ^ACTIs the actual value of the rolled material speed on the exit side of the rolling stand 2c measured by the rolled material speed meter 16c. Therefore, the actual rolling material speed value v_i ^ACTIs the rolled material speed command value v_i ^REFBy providing such a main engine speed command value to the main engine speed control means 10b, the equation (19), which is a condition for constant mass flow, can be realized.
[0052]
FIG. 5 is a control block diagram of the control device of FIG. The above control calculation is executed in the tension control means 20 in FIG.
[0053]
In the rolled material speedometers 16a to 16c, in addition to directly measuring the rolled material speed using a speedometer based on the Doppler effect using a wave such as a laser as described above, the advanced rate f is calculated by a model formula, and the advanced rate is calculated. Ratio f and rolling roll peripheral speed V_RThere is also a method of calculating the rolled material speed v from the following formula. If the rolled material speed v is calculated using the advance rate f, it can be used as a backup when the speedometer fails, and can also be used as a noise removal filter of the speedometer.
[0054]
First, the model formula of the advance rate f is, for example,
f = ar^b… (21)
It is expressed as Here, a and b are coefficients, r is a rolling reduction, and the rolling reduction r is obtained by using the entrance side thickness H and the exit side thickness h of the rolling stand.
r = (Hh) / H (22)
It is expressed as
[0055]
Rolled material speed v and rolling roll peripheral speed V_RThe relationship is
v = (1 + f) V_R… (23)
Is represented by
[0056]
When calculating the advance rate f using the model formula, the accuracy of the model formula is important, and it is necessary to identify the coefficients a and b with high accuracy. The regression equation for identification is
y = cx + d (24 °)
y = ln (v / V_R-1), x = ln (r), d = ln (a)
Is represented by
[0057]
By identifying the coefficients c and d by the regression equation, the following:
c = ln (a), b = d (25)
Thus, the coefficients a and b in the equation (21) can be obtained. The regression can be obtained by applying a sequential least squares method, a general least squares method that handles data collectively, or the like.
[0058]
The parameters of the advanced rate model equation (21) obtained in this manner are classified according to the characteristics of the rolled material and stored in a parameter table in a computer. When the speedometer 16 cannot be used due to a failure or the like, similar characteristics are obtained. The advanced rate f is calculated by taking out the parameters from the parameter table for the rolled material having the advanced rate f and the rolling roll peripheral speed V_RFrom (23) is used as the rolled material speed v. Thus, the above control method can be continued even when the speedometer cannot be used.
[0059]
In addition, the parameters of the advanced rate model formula are stored in the parameter table in the computer, classified according to the characteristics of the rolled material. Take out and calculate the advanced rate, compare the rolled material speed calculated value calculated from the advanced rate and the rolling roll peripheral speed, and the actual rolled material speed value measured with a speedometer, if the difference exceeds a predetermined threshold The rolled material speed calculation value is used as the rolled material speed. Thus, when a large noise is applied to the speedometer, the value can be taken in to prevent a situation that causes disturbance to the control.
[0060]
In the method shown in FIG. 5, it is possible to keep the mass flow after the tension is established, but it is necessary to form an initial state of the tension. Therefore, after the rolled material is caught in the downstream rolling stand, looper control is performed or the invention of FIGS. 1 and 2 is performed to establish tension.
[0061]
According to the present embodiment, when there is a rolling material speed meter that measures the rolling material speed between the rolling stands, stable tension control can be performed by keeping the mass flow constant. When the rolling material speed meter cannot be used due to a failure or the like, the rolling material speed can be calculated with high accuracy using the identified advanced rate model, and the mass flow can be kept constant.
[0062]
<Third embodiment>
Next, a third embodiment will be described. FIG. 6 is a diagram showing a configuration of the third embodiment of the present invention.
[0063]
In FIG. 6, rolling material speedometers 16a, 16b, 16c are installed on the exit sides of the rolling stands 2a, 2b, 2c. Based on the rolling roll gap S of each rolling stand measured by the rolling-down means 17a, 17b, 17c, it is possible to predict the thickness of the exit side of each rolling stand, and calculate the exit side sheet thickness by the exit side thickness calculating means 18a. To 18c.
[0064]
When controlling the tension of the rolled material 1 in the tension control means 21, the exit sheet thickness h of each stand is calculated by the output sheet thickness calculating means 18, and the tension calculating means 12 a and 12 b are used by using this and the rolling material speed v. The tension of the exit-side rolled material is calculated, and a main machine speed command value for reducing the deviation from the tension target value in the control calculation means 13a, 13b is output to the main machine speed control means 10a, 10b. The tension calculation in the tension calculation means 12 is performed based on Expression (16) which is a basic expression for generating tension.
[0065]
NO. Inlet material speed V of i + 1 stand_{i + 1}Can not be measured directly, the reverse speed b and the roll peripheral speed V_RUsing,
V_{i + 1}= (1-b_{i + 1}) V_{Ri + 1}
= (1 + f_{i + 1}) (H_{i + 1}/ H_{i + 1}) V_{Ri + 1}
= (H_{i + 1}/ H_{i + 1}) V_{i + 1}… (26)
Calculate with
[0066]
The rolled material Young's modulus E and the tension feedback coefficient have a parameter table based on the classification of the rolled material characteristics. Further, the tension calculation in the tension calculation means 12 is performed by using a simple model formula (17) derived from the basic formula (16) of the tension generation.
[0067]
As described in the second embodiment, the rolled material speed can be obtained by directly measuring the rolled material speed using a speedometer or the like, and calculating the advanced rate, and calculating the advanced rate and the rolling roll peripheral speed. There is also a method of calculating the rolled material speed from the above.
[0068]
FIG. 7 is a control block diagram of the control device of FIG. In the tension calculating means 12a and 12b, the rolled material tension t is calculated using the method of the above formula (16)._fiIs calculated by the control operation means 13 so as to cause the rolling material tension to follow the tension command value, and the main machine speed control means 10 causes the rolling main motor to follow the speed command value. 5 is controlled.
[0069]
FIG. 8 is also a control block diagram according to the third embodiment. In the tension calculating means 12, the rolled material tension t is calculated using the method of the above equation (17)._fiIs calculated.
[0070]
Thus, according to the third embodiment, when there is a speedometer for measuring the speed of the rolled material between the rolling stands, stable tension control is performed by calculating the tension of the rolled material with high accuracy using a model equation of tension generation. Can be implemented. Even when the speedometer cannot be used due to negotiations or the like, the rolled material speed can be calculated with high accuracy by the identified advanced rate model, and stable tension control can be continued.
[0071]
<Fourth embodiment>
Next, a fourth embodiment will be described. FIG. 9 is a diagram illustrating the configuration of the fourth embodiment.
[0072]
9 includes the torque arm identification means 22. The torque arm identification means 22 calculates the rolling load P of each rolling stand, the rolling torque G, and the rolling material tension t between the rolling stands, which can be measured in real time._fThe rolling load P of each rolling stand, the rolling torque G, the incoming side plate thickness H, the outgoing side plate thickness h, and the rolled material tension between the rolling stands can be used to identify the sequential torque arm coefficient or to measure in real time. t_fIs used to sequentially identify the torque arm, and the tension calculating means 12a and 12b calculate the rolled material tension based on the torque arm coefficient or the torque arm.
[0073]
Specifically, the torque arm identification means 22 performs the following calculation.
[0074]
First, a case where the torque arm coefficient is identified will be described. In addition to the basic formulas (1), (2) and (3),
A = 2aL_d… (27)
Consider. Here, A is a torque arm, a is a torque arm coefficient, L_dIs the projected contact arc length.
[0075]
Of the influence coefficients in the equations (1) and (2), γ and δ can be expressed as follows. That is,
γ_i= A_Ri・ R_i… (28)
δ_i= A_Ri-1・ R_i… (29)
Where A_RIs the cross-sectional area of the rolled material delivery side, and R is the rolling roll radius.
[0076]
NO. From the i-1 stand 2a, the NO. Consider the i + 1 stand 2c. From equations (1) to (3),
G_i-1= A_i-1P_i-1-A_Ri-1R_i-1t_fi-1
+ A_Ri-2R_i-1t_fi-2… (30)
G_i= A_iP_i-A_RiR_it_fi
+ A_Ri-1R_it_fi-1… (31)
G_{i + 1}= A_{i + 1}P_{i + 1}-A_{Ri + 1}R_{i + 1}t_{fi + 1}
+ A_RiR_{i + 1}t_fi… (32)
Here, NO. i + 1 to NO. The tension between the i + 2 stands is known (assuming that it can be accurately measured by performing looper control or the like). It is assumed that the tension upstream of the i-2 stand is zero. When both sides of the equations (30) to (32) are normalized by the roll radius R, respectively,
(Equation 10)

It becomes.
[0077]
Each of the left sides and the right sides of the equations (33) to (35) is added, and
[Equation 11]

Get. Here, applying equation (27),
(Equation 12)

To find the torque arm coefficient a, the regression equation is
(Equation 13)

Is defined.
[0078]
The torque arm coefficient is calculated from the actual values of the rolling load, the rolling torque, the thickness of the inlet / outlet plate, the tension, and the like, by sequentially applying the least squares method based on the regression equation.
[0079]
Next, a case where the torque arm is identified will be described. The same calculation is performed up to the expression (36), but the expression (37) is not used.
[Equation 14]

Identified as
[0080]
Next, the tension is calculated from the identified torque arm coefficient. From equations (27), (33), (34), and (35),
(Equation 15)

And the material tension between stands t_fCan be calculated.
[0081]
Similarly, in the case of the identified torque arm A, the tension t_fCan be requested.
[0082]
In the above, in order to obtain the tension between the two rolling stands, the relational expression of the torque arm of the three rolling stands was considered. Can be easily applied.
[0083]
The control operation means 13 calculates a speed command value of the rolling main motor 5 so that the obtained rolling material tension follows the tension command value, and the main machine speed control means 10 controls the rolling master so as to follow the speed command value. The speed of the electric motor 5 is controlled.
[0084]
Thus, according to the fourth embodiment, it is possible to accurately calculate the real-time change of the torque arm coefficient or the torque arm A, capture the change in the state during rolling, and accurately consider the influence on the tension.
[0085]
【The invention's effect】
According to the present invention, it is possible to improve the accuracy of tension estimation when looper control is not used, thereby improving the tension control performance, and achieving more stable operation and higher quality of products.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing a first embodiment of a tension control device according to the present invention.
FIG. 2 is a control block diagram of the tension control device of FIG.
FIG. 3 is an explanatory diagram for explaining a torque applied to a looper according to the first embodiment;
FIG. 4 is a functional block diagram showing a tension control device according to a second embodiment of the present invention.
FIG. 5 is a control block diagram of the tension control device of FIG. 4;
FIG. 6 is a functional block diagram showing a third embodiment of the tension control device according to the present invention.
FIG. 7 is a control block diagram of the tension control device of FIG. 6;
FIG. 8 is a control block diagram showing a third embodiment of the tension control device according to the present invention.
FIG. 9 is a functional block diagram showing a fourth embodiment of the tension control device according to the present invention.
FIG. 10 is a diagram showing an entire configuration of a conventional tension control device.
FIG. 11 is an explanatory diagram for explaining the concept of a conventional tension control device.
[Explanation of symbols]
1 rolled material
2 Rolling stand
3 Main engine speed control system
4 mm rolling load detector (L / C)
5 mm rolling main motor
6 looper
7 looper motor
8 tension detector
9 ° angle detector
10 Main engine speed control means
11 ° looper angle control means
12 tension calculation means
13 Control calculation means
14 tension control means
15 looper control means
16mm rolled material speedometer
17 ° rolling means
18 Outboard thickness calculation means
19 Rolled material speed control means
20 ° tension control means
21 ° tension control means
22 ° torque arm identification means
23 tension control means
24 ° tension control means

Claims (12)

Tension calculating means for calculating the rolled material tension between the rolling stands; control calculating means for calculating the speed command value of the main rolling motor so that the calculated rolled material tension follows the tension command value; and the calculated speed command A main machine speed control means for controlling a speed of a rolling main motor so as to follow a value, wherein a tension control device of a tandem rolling mill that rolls a rolled material in series through a plurality of rolling stands and rolls the tension material. The means is configured to perform rolling from one of an output of a tension detector installed between the rolling stands, an output of a tension detector attached to a looper device installed between the rolling stands, and a calculation output from power for driving the looper. A tension control device for a tandem rolling mill, wherein a tension control is performed by detecting a material tension and using the detected rolled material tension as an actual tension value. A looper angle control unit that calculates a looper angle command value in accordance with the characteristics of the rolled material and the characteristics of the looper drive, and controls the actual looper angle to be equal to the looper angle command value; The tension control device according to claim 1, wherein the looper acts as a tension detector through control of the looper angle by the angle control means. The tension calculating means controls the start of the tension calculation and the control by the control calculating means, after a fixed time after the rolled material is bitten into the downstream rolling stand, or when the rolled material is bitten into the downstream rolling stand. The tension control device according to claim 1 or 2, wherein the tension control device starts after a predetermined time after another tension control is activated. The looper angle control means, the looper angle command value, the total torque supporting the looper calculated according to the size and rolling conditions of the rolled material does not exceed a value obtained by multiplying the maximum torque that the looper can generate by a predetermined safety factor The tension control device according to claim 2, wherein the tension is determined as follows. Main machine speed control means for controlling the speed of the rolling motor to follow the given speed command value, and rolled material speed measuring means for measuring the rolled material speed on the exit side of the rolling stand, a plurality of rolled material In a tension control device of a tandem rolling mill that performs rolling by passing through a series of rolling stands in series, NO. An outlet side thickness calculating means for calculating the thickness of the outlet side of the stand and a downstream NO. i + 1 The rolled material speed measured at the outlet side of the stand and the NO. i. The sheet thickness on the exit side of the stand, and the NO. Using the sheet thickness on the outlet side of the i + 1 stand, the NO. and a rolling material speed control means for calculating a rolling material speed command value on the exit side of the stand. A tension control device for a tandem rolling mill, wherein a speed command value of a rolling main motor of an i-stand is calculated and provided to said main machine speed control means. The rolled material speed measuring means is a speedometer for directly measuring the rolled material speed, and a speed calculating means for calculating the advanced rate using a model formula and calculating the rolled material speed from the obtained advanced rate and rolling roll peripheral speed. The tension control device according to claim 5, further comprising: selectively using one of the speedometer and the speed calculation means. The rolled material speed measuring means identifies parameters in the model of the advanced rate in a state where the speedometer can be used, classifies the parameters according to the characteristics of the rolled material, stores the parameters in a parameter table, and uses the speedometer when the speedometer cannot be used. The method according to claim 6, wherein a parameter corresponding to a rolled material having similar characteristics is taken out from the parameter table, an advanced rate is calculated, and a rolled material speed is calculated from the advanced rate and a rolling roll peripheral speed. A tension control device as described. The rolled material speed measuring means, when calculating the rolled material speed from the advance rate and the rolling roll peripheral speed, identify the parameters in the model formula of the advanced rate in a state where the speedometer can be used, and the parameters of the properties of the rolled material Is stored in the parameter table, and the parameters corresponding to the rolled material having similar characteristics are taken out from the parameter table to calculate the advanced rate, and the rolled material speed calculated value calculated from the advanced rate and the rolling roll peripheral speed and Comparing the rolled material speed actual value measured by a speedometer, if the difference exceeds a predetermined threshold, using the rolled material speed calculated value as the rolled material speed used for control The tension control device according to claim 6. Tension calculating means for calculating the rolled material tension between the rolling stands; control calculating means for calculating the speed command value of the main rolling motor so that the calculated rolled material tension follows the tension command value; and the calculated speed command Main machine speed control means for controlling the speed of the rolling main motor to follow the value, and rolled material speed measuring means for measuring the rolled material speed on the exit side of the rolling stand, the rolled material to a plurality of rolling stands In a tension control device of a tandem rolling mill that performs rolling in series, the tension calculating means includes a rolled material Young's modulus E, a stand-to-stand distance L, an incoming material speed V, an outgoing material speed v, NO. The suffix indicating the i-stand is i, NO. The suffix indicating the i + 1 stand is i + 1, NO. i stand and NO. The rolling material tension between the i + 1 stand as _{t fi,} basic equation _t of the rolling material tension _{t fi} tensioning _{f1 = (E i / L i} ) ∫ (V i + 1 -v i) dt
A tension control device for a tandem rolling mill. Tension calculating means for calculating the rolled material tension between the rolling stands; control calculating means for calculating the speed command value of the main rolling motor so that the calculated rolled material tension follows the tension command value; and the calculated speed command Main rolling stock speed control means for controlling the speed of the rolling main motor so as to follow the value, and rolling material speed measuring means for measuring the rolling material speed on the exit side of the rolling stand. In the tension control device of the tandem rolling mill that performs rolling in series with the tension, the tension calculating means includes a tension feedback coefficient of K ₁₀ , a rolled material Young's modulus of E, a distance between stands of L, an exit side material speed of v, NO . The suffix indicating the i-stand is i, NO. i stand and NO. Assuming that the rolled material tension between the (i + 1) th stand is t _fi , the rolled material tension t _fi is a simple model formula.

A tension control device for a tandem rolling mill. The rolled material speed measuring means includes a speedometer for directly measuring the rolled material speed, an advanced rate obtained using a model formula, and a speed calculating means for calculating a rolled material speed from a rolling roll peripheral speed, 11. The tension control device according to claim 9, wherein one of the speedometer and the speed calculation means is selectively used. Tension calculating means for calculating the rolled material tension between the rolling stands; control calculating means for calculating the speed command value of the main rolling motor so that the calculated rolled material tension follows the tension command value; and the calculated speed command A main machine speed control means for controlling the speed of the rolling main motor so as to follow the value, a tension control device of a tandem rolling mill that rolls a rolled material in series through a plurality of rolling stands and measures in real time The first data group consisting of rolling loads, rolling torques, and rolling material tensions between rolling stands that can be performed, and rolling loads, rolling torques, and incoming side plates of each rolling stand that can be measured in real time. The torque arm for identifying the torque arm sequentially using any one of the second data group consisting of the thickness, the exit side plate thickness, and the rolled material tension between the rolling stands. Comprising a beam identification means, the tension calculating means tension control apparatus of a tandem rolling mill, characterized in that for calculating the rolling material tension based on the torque arm coefficient or torque arm identified by said torque arm identifying means.

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