JP3709028B2 - Cold tandem rolling method and cold tandem rolling mill - Google Patents

Description

【００２０】
表１では製品板厚を０．６mm未満に圧延する薄手系および製品板厚を０．６mm以上に圧延する厚手系の最終スタンドの圧延条件を想定した。但し、変形抵抗を表す式（３）の定数は、予め引張試験によって得られた値、ａ＝６７kgf ・mm^-2、ε₀ ＝０．０３、ｎ＝０．２とし、摩擦係数は冷間圧延の最終スタンドにおける通常の圧延条件において得られた代表的な摩擦係数μ＝０．０５を用いた。なお、表１中のロール半径Ｒは通常の冷間タンデム圧延機の最終スタンドに使用されている代表的なロール半径とし、圧下率ｒ、圧延荷重Ｐ、ワークロール速度Ｖ_R 、素材板厚Ｈ₃ は通常の冷間タンデム圧延における代表的な圧延条件の範囲の値を用いている。
【００２１】
前述したように安定した冷間タンデム圧延を行うためには張力負加比κは０．３以上必要である。そのためには、表１（コイラー系が単位時間になす仕事Ｗ_O と最終スタンド圧延機が単位時間になす仕事Ｗ_M の比を表したもの。）から分かるように、コイラー系の仕事は、製品板厚が０．６mmの製品を製造する冷間タンデム圧延機では最終スタンドの圧延機の仕事の５０％以上、また、製品板厚が０．２mmの薄手系の製品を製造する冷間タンデム圧延機では最終スタンドの圧延機の仕事の３５％以上必要であることが分かる。即ち、コイラー系の主電動機の出力は、製品板厚が０．６mmの製品を製造する冷間タンデム圧延機では最終スタンドの圧延機の主電動機の５０％以上、また、製品板厚が０．２mmの薄手系の製品を製造する冷間タンデム圧延機では最終スタンドの圧延機の主電動機の出力の３５％以上必要である。
【００２２】
なお、出側コイラーのみで大きな張力を発生させる代わりに、コイラー切り替え時も考慮して最終スタンドと出側コイラーの間に張力負荷用のブライドルロールを設置しても良い。この場合は、出側コイラー１基と出側ブライドルロールの出力の合計が上記条件を満足すればよい。以上のことをパラメータ平均板厚ｈ［ｍｍ］を用いて整理すると、出側コイラー１基の主電動機の出力または出側コイラー１基の出側ブライドルロールの主電動機の出力の合計をＷ_c 、最終スタンドの圧延機の主電動機の出力をＷ_M とした場合、Ｗ_c ≧（０．３７５ｈ＋０．２７５）Ｗ_M ［ｋＷ］である冷間タンデム圧延機が必要であることが分かる。
【００２３】
なお、その際前述したように全圧延張力（圧延張力に板厚と板幅を乗じた値）は圧延機入側と出側で同じ値にすることによって、圧延機には過剰な負荷（メカロスも含む）はかからなくなり電力原単位も向上することから、圧延機入・出側で全圧延張力を等しくする方が好ましい。
以上のように、出側コイラー１基の出力または出側コイラー１基と出側ブライドルロールの出力の合計を、最終スタンドの圧延機の主電動機の出力の３５％以上あるいは５０％以上にすることによって、最終スタンドにおいて圧延材の変形抵抗の３０％以上、好ましくは４０％以上の圧延張力を負荷する高張力圧延を実現可能とし、それにより、ヒートスクラッチの発生防止を図ることができる。
【００２４】
しかしながら、張力を変形抵抗の３０％〜４０％以上にした場合、板端部の張力応力レベルが上昇するので板破断が生じやすくなる。特にノートリム材を圧延するような場合には、板端部に微少なクラックが入りやすく、そのため板破断は一層生じやすくなる。したがって、ヒートスクラッチおよび板破断を同時に防止するためには、張力が変形抵抗の３０％〜４０％以上の高張力圧延を行うと共に、板端部の過大な張力が加わることが原因で生じるような板破断を防止するための張力分布の制御が必要である。
【００２５】
【課題を解決するための手段】
本発明は上述したような従来法の問題点を解決するためのものであり、
本発明の請求項１は、形状制御装置を備えた冷間圧延機を４スタンド以上有する冷間タンデム圧延機において、タンデム圧延機の入側および出側において圧延材の板幅を測定し、この板幅測定値から、タンデム圧延機入側と出側の板幅変化量を算出し、この板幅変化量が所定の予め定めた板幅変化量の許容値を超えないよう形状制御装置を制御すると共に、少なくとも最終スタンドにおいて圧延材の変形抵抗の３０％以上の圧延張力を負荷して圧延することを特徴とする冷間タンデム圧延方法である。
【００２６】
請求項２は、形状制御装置を備えた冷間圧延機を４スタンド以上有する冷間タンデム圧延機において、タンデム圧延機の入側、出側およびタンデム圧延機間の少なくとも１スタンド以上の圧延機の出側において圧延材の板幅を測定し、
タンデム圧延機の第１スタンドとタンデム圧延機間で出側板幅を測定したより上流側にあるスタンドとの間と、出側板幅を測定したより上流側にあるスタンドの下流に隣接するスタンドと出側板幅を測定したより上流側にあるスタンドより下流で且つより上流側にある出側板幅を測定したスタンドとの間、および出側板幅を測定した最下流側にあるスタンドの下流に隣接するスタンドと最終スタンドとの間とにより逐次スタンド区間を構成し、
上記測定結果から、各スタンド区間毎に、板幅変化量を算出し、このスタンド区間の板幅変化量が、予め各スタンド区間毎に定めた板幅変化量許容値を超えないように、形状制御装置を制御すると共に、少なくとも圧延材の変形抵抗の３０％以上の圧延張力を負荷して圧延する圧延方法である。
【００２７】
請求項３は、形状制御装置を備えた冷間圧延機を４スタンド以上有する冷間タンデム圧延機において、タンデム圧延機の入側、およびタンデム圧延機の各圧延機出側において圧延材の板幅を測定し、この板幅測定値から、タンデム圧延機の各圧延機の入側と出側の板幅変化量を算出し、これらの板幅変化量が、タンデム圧延機の各圧延機の入側と出側においてそれぞれ予め定めた板幅変化量の許容値を超えないよう形状制御装置を制御すると共に、少なくとも最終スタンドにおいて圧延材の変形抵抗の３０％以上の張力を付加して圧延することを特徴とする冷間タンデム圧延方法である。
【００２８】
請求項４は、各スタンドに形状制御装置を備えた４スタンド以上の冷間圧延機を有する冷間タンデム圧延機であって、このタンデム圧延機の少なくとも入側および出側に板幅測定装置を有し、冷間タンデム圧延機の出側に、コイラー、またはコイラーとブライドルロールを有し、このコイラー１基の主電動機の出力、またはコイラー１基の主電動機の出力とブライドルロールの主電動機の出力との合計出力と、冷間タンデム圧延機の最終スタンドの主電動機の出力と、この冷間タンデム圧延機によって圧延する製品の平均板厚とが、下記の関係を満たすことを特徴とする冷間タンデム圧延機である。
【００２９】
Ｗ _c ≧（０．３７５ｈ＋０．２７５）Ｗ _M
但し、Ｗ _c ：コイラー１基の主電動機の出力、またはコイラー１基の主電動機の出力とブライドルロールの主電動機の出力との合計出力
Ｗ _M ：冷間タンデム圧延機の最終スタンドの主電動機の出力
ｈ：冷間タンデム圧延機によって圧延する製品の平均板厚［ｍｍ］
【００３０】
請求項５は、冷間タンデム圧延機の圧延機間の少なくとも１箇所に、板幅測定装置を有することを特徴とする請求項４に記載の冷間タンデム圧延機である。
【００３１】
【発明の実施の形態】
そこで、次に、本発明は板幅の測定・制御することによって張力分布の制御を行い板破断を防止するものである。以下、本発明の方法について説明を行う。
先ず、本発明の基本的な原理となっている板幅変化のメカニズムについて、板圧延解析システム（３次元剛塑性ＦＥＭによる板変形解析と分割モデルによる汎用のロール変形解析を連成させた解析システム）を用いて解析した結果から得られた知見に基づいて説明する。
【００３２】
図４，５に、圧延機形状制御装置（ここではワークロールベンディング装置を備えており、ロールベンディング力を変化させている）を変化させて計算した場合のロールバイト入口近傍、ロールバイト内、ロールバイト出口近傍における板幅の変化およびロールバイト出口における幅方向の張力の変化を示す。なお、ここでは、ロールバイト入口近傍、ロールバイト内、ロールバイト出口近傍の３つの領域を簡単にロールバイト近傍と表現することにする。これらの図より、ディクリース側（形状が端伸び側：Ｆ＜０）へベンディング力を作用させた場合、ロールバイト近傍での幅広がり量が増加し、張力分布に関しては、板端から、１００mm程度の領域の張力が減少しているのがわかる。これに対して、インクリース側（形状が中伸び側：Ｆ＞０）へベンディング力を作用させた場合、ロールバイト近傍で板幅減少を示すようになり、張力分布に関しては、板端部から１００mm程度の領域の張力が増加しているのがわかる。このように、ロールバイト近傍における板幅変化は、板端の張力が高くなるほど板幅が減少（幅縮み）し、板端の張力が低くなるほど板幅が増加（幅広がり）する傾向にある。
板端からｌ_e ＝５０mmの範囲の板端部の平均張力をσ′とし、ロールバイト近傍での板幅変化量をΔＷとすると、σ′とΔＷの関係は図６に示すような関係で表わせ、圧延条件（接触弧長ｌ_d ）により変化することがわかる。したがって、ロールバイト近傍の板幅変化量ΔＷは、σ′，ｌ_d の関数として次式のように表わすことができる。
ΔＷ＝ΔＷ（σ′，ｌ_d ） （４）
また、板端部の平均張力σ′は、圧延条件、すなわち、ロールベンディング力Ｆ、スタンド入側・出側の単位断面積あたりの平均張力σ_b ，σ_f 、出側板厚ｈ′、板幅Ｗ、接触弧長ｌ_d によって変化し、これらの関数として次式のように表すことができる。
σ′＝σ′（Ｆ，σ_b ，σ_f ，ｈ′，Ｗ，ｌ_d ） （５）
このように、板幅変化、板端部の張力および圧延条件（ロールベンディング力、平均張力等）には式（４）、（５）のような関係があることから、本発明では、板幅を検出端として、張力の変動を板幅変動に置き換えて、板幅制御を行うことによって、ヒートスクラッチを防止し且つ板破断を防止しようとするものである。すなわち、板破断を起こさない限界の板端部の平均張力σ′＝σ′_lim とすると、σ′_lim に基づき、式（４）から許容の板幅変化ΔＷ_lim を定め、板幅の変化を観測し許容の板幅変化ΔＷ_lim を超えるような板幅減少を生じないように板幅制御量を定め、この板幅制御量に基づき式（５）より形状制御装置の操作量としてロールベンディング力Ｆまたは入側・出側平均張力σ_b ，σ_f を求め、これに基づいて制御することにより、板端部に過大な張力が加わることが原因で生じるような板破断を防止することができる。なお、限界の板端部の平均張力σ′_lim は予め引張試験で求めた圧延材の破断応力より小さい（５〜１０kgf ・mm^-2小さい）値を設定することが好ましい。また、この制御においては、入側・出側張力を低減するよりも、ロールベンディング力等を操作して幅方向張力分布を変化させる方が高生産性を維持するためには好ましい。
【００３３】
なお、式（５）では説明を簡単にするために、形状制御装置としてはロールベンディング装置におけるベンディング力のみを考慮したが、ロールクロス装置、ロール軸方向シフト装置、ロールプロフィル制御装置の操作量と板幅変化量との関係を求めておき、所定の張力以下となる板幅変化量を求め、この幅変化量以下となるように張力分布を含めて張力を制御することができる。また、これらの形状制御装置をいくつか併用して張力を制御することや、これらの形状制御装置をロールベンディング力の代わりに用いることができることは言うまでもない。
【００３４】
次に、本発明を実施例である図１を用いて詳細に説明する。図１は４スタンドからなる冷間タンデム圧延機であり、圧延材１を圧延している。各スタンドの圧延機は４段圧延機であり、ワークロール２ａ〜２ｄ、バックアップロール３ａ〜３ｄおよび形状制御装置４ａ〜４ｄを備えた４段圧延機と、演算処理装置８とを有している。タンデム圧延機の入側と出側には、入側コイラー５ａ、出側コイラー５ｂ、入側板幅測定装置６ａおよび出側板幅測定装置６ｂが設置されている。
【００３５】
本発明の冷間タンデム圧延機においては、図１に示すようにこのタンデム冷間圧延機の少なくとも入側および出側に設ければ良いが、後述するように、タンデム圧延機の任意のスタンド間にも設けることが好ましい。
また、この例では、出側コイラー５ｂの主電動機は、最終スタンドの圧延機の主電動機の出力の５０％以上の出力を有しており、各スタンド間の張力は圧延材の変形抵抗の３０％〜４０％以上の圧延張力を付与して圧延可能である。
【００３６】
このような冷間タンデム圧延機において、圧延材１が、圧延材の変形抵抗の３０％〜４０％以上の張力を付与して圧延され、タンデム圧延機の入側および出側においては、板幅測定装置６ａ，６ｅより、圧延材１の板幅Ｗ⁽⁰⁾ ，Ｗ⁽⁴⁾ が検出されている（但し、（０）はタンデム圧延機入側、（４）は圧延スタンドの番号を示す）。演算処理装置８内では、検出されたタンデム圧延機の入側・出側における板幅Ｗ⁽⁰⁾ ，Ｗ⁽⁴⁾ から、第１〜４（１；４と表わす。以下同じ）スタンドの圧延機での板幅変化の累積値、すなわち、タンデム圧延機全体での板幅変化量をΔＷ^(1;4) とすると、ΔＷ^(1;4) は次式から計算される。
ΔＷ^(1;4) ＝Ｗ⁽⁴⁾ −Ｗ⁽⁰⁾ （＋：板幅増加、−：板幅減少） （６）
また、これを一般的に第ｎ〜Ｎ（ｎ；Ｎと表わす。以下同じ）スタンドの圧延機の場合として表すと次式で表される。
ΔＷ^(n;N) ＝Ｗ^(N) −Ｗ^(n-1) （６′）
ただし、ΔＷ^(n;N) ：第ｎ〜Ｎスタンドの圧延機間の累積板幅変化、Ｗ^(n-1) ：第ｎスタンド入側の板幅、Ｗ^(N) ：第Ｎスタンド出側の板幅
この板幅変化量ΔＷ^(1;4) が、タンデム圧延機内で板破断が生じる可能性がある負側（板幅減少側）の許容値ΔＷ_lim ^(1;4) を超えた場合、タンデム圧延機内で修正すべき板幅修正量ΔＷ_c ^(1;4) （板幅増加側への修正量）が例えば、次式のように計算される。
ΔＷ_c ^(1;4) ＝ΔＷ^(1;4) −ΔＷ_lim ^(1;4) （７）
また、これを一般的に第ｎ〜Ｎスタンドの圧延機の場合として表すと次式で表される。
ΔＷ_c ^(n;N) ＝ΔＷ^(n;N) −ΔＷ_lim ^(n;N) （７′）
ただし、ΔＷ_c ^(n;N) ：第ｎ〜Ｎスタンドの圧延機での板幅修正量、ΔＷ_lim ^(n;N) ：第ｎ〜Ｎスタンドの圧延機での板幅変化の許容値
また、タンデム圧延機での許容値ΔＷ_lim ^(1;4) は、例えば、式（４）から求まる第ｉスタンドの板幅変化量の許容値ΔＷ_lim ⁽ⁱ⁾ （ｉ＝１〜４）、第ｉスタンドの板幅変化ΔＷ⁽ⁱ⁾ （ｉ＝１〜４）とすると、図１０に示すように、タンデム圧延機内のいずれかのスタンドでΔＷ⁽ⁱ⁾ −ΔＷ_lim ⁽ⁱ⁾ だけ変化した場合、板破断を起こす可能性があので、ΔＷ⁽ⁱ⁾ −ΔＷ_lim ⁽ⁱ⁾ の最小値を基準にして、タンデム圧延機全体としての許容値ΔＷ_lim ^(1;4) は、次式のように計算される。
ΔＷ_lim ^(1;4) ＝ΔＷ^(1;4) −min （ΔＷ⁽ⁱ⁾ −ΔＷ_lim ⁽ⁱ⁾ ）（ｉ＝１〜４）（８）
ただし、min( )は、第ｉ＝１〜４スタンド内での最小値を表す。
また、これを一般的に第ｎ〜Ｎスタンドの圧延機の場合として表すと次式で表される。
ΔＷ_lim ^(n;N) ＝ΔＷ^(n;N) −min （ΔＷ⁽ⁱ⁾ −ΔＷ_lim ⁽ⁱ⁾ ）（ｉ＝ｎ〜Ｎ）（８′）
この板幅修正量ΔＷ_c ^(1;4) に基づき、第１〜４スタンド内で板破断が生じる可能性があるスタンドを特定し、そのスタンドの形状制御装置によってベンディング力あるいはシフト量などを調整し優先的に板幅を制御することによって板破断防止制御が実現できる。なお、形状制御装置のベンディング力、シフト量などの制御量は、板幅修正量ΔＷ_c ^(1;4) に応じて式（４）、式（５）より演算する。ところで、この例の場合、タンデム圧延機内のスタンド間に板幅測定装置を有していないので、形状制御装置を制御すべきスタンドを例えば、以下のような方法によって、特定し制御する。
【００３７】
すなわち、第ｉ＝１〜４スタンドのロールベンディング力Ｆ⁽ⁱ⁾ 、スタンド入側・出側の単位断面積あたりの平均張力σ_b ⁽ⁱ⁾ ，σ_f ⁽ⁱ⁾ 、出側板厚ｈ′⁽ⁱ⁾ 、接触弧長ｌ_d ⁽ⁱ⁾ を現状の圧延条件の設定値および測定値より求め、式（５）より、第ｉスタンドの板端部の平均張力をσ′⁽ⁱ⁾ （ｉ＝１〜４）を推定する。σ′⁽ⁱ⁾ が最も高いスタンドが板破断の可能性が高いので、このスタンドを第ｊスタンドとして制御を行うスタンドとして特定する。なお、この場合、式（５）において各スタンド出側の板幅の絶対値Ｗ⁽ⁱ⁾ が必要となるが、各スタンドの板幅変化ΔＷ⁽ⁱ⁾ は、板幅Ｗ⁽ⁱ⁾ に比べ微小であるので、板幅Ｗ⁽ⁱ⁾ は各スタンドで一定であると近似する。第ｊスタンドの板幅修正量ΔＷ_c ⁽ⁱ⁾ をΔＷ_c ⁽ⁱ⁾ ＝ΔＷ_c ^(1;4) とし、式（４）、式（５）より、第ｊスタンドの形状制御装置の操作量Ｆ_c ⁽ⁱ⁾ を算出する。この操作量Ｆ_c ⁽ⁱ⁾ に基づき、第ｊスタンドの形状制御装置を操作する。操作後、同様に、第ｉ＝１〜４スタンドの板端部の平均張力をσ′⁽ⁱ⁾ （ｉ＝１〜４）を求め、次に制御を行うべき第ｊスタンドを特定し、第ｊスタンドの形状制御装置の操作量を設定し、板幅変化量ΔＷ^(1;4) が負側の許容値ΔＷ_lim ^(1;4) 以下になるまで、形状制御装置４ａ〜４ｄによる制御を繰り返し実施する。
【００３８】
また、上述のように、タンデム圧延機の入側・出側の板幅測定装置に加え、タンデム圧延機内の第ｋ〜第ｋ＋１スタンド間（１≦ｋ＜４）に板幅測定装置を設けることによって、第ｉ＝１〜ｋスタンド間および第ｉ＝ｋ＋１〜４スタンド間の板幅変化ΔＷ^(1;k) およびΔＷ^((k+1);4) をそれぞれ求めることができ、また、第８′式より、第ｉ＝１〜ｋスタンド間の板幅変化の許容値ΔＷ_lim ^(1;k) 、第ｉ＝ｋ＋１〜４スタンド間の板幅変化の許容値ΔＷ_lim ^((k+1);4) を求め、上記と同様の方法で、ｉ＝１〜ｋスタンド間および第ｉ＝ｋ＋１〜４スタンド間のそれぞれで、板破断の可能性が大きく形状制御装置４ａ〜４ｄを操作すべきスタンドそれぞれ特定し、各許容値ΔＷ_lim ^(1;k) 、ΔＷ_lim ^((k+1);4) を超えないように形状制御装置４ａ〜４ｄを制御する。この場合、上述の場合に比べ、板幅測定装置が増えることによって板幅変化の不明なスタンド数が減ることによって、より高精度に板幅制御することが可能となる。
【００３９】
さらに、これをタンデム圧延機の第１圧延機の入側、およびタンデム圧延機の最終圧延機の出側ほか、タンデム圧延機間の任意の１以上の圧延機、例えば上流側からｋスタンド、ｋスタンドより下流側のｊスタンドおよび更にこれより下流側のｍスタンドの出側において板幅を測定する例により説明すると、出側板幅を測定したタンデム圧延機間の圧延スタンドについて、上流側から下流側に向かって次のように逐次スタンド区間を構成する。
【００４０】
すなわち、タンデム圧延機の第１スタンドとタンデム圧延機間で出側板幅を測定したより上流側にあるＫスタンドとの間と、出側板幅を測定したより上流側にあるＫスタンドの下流に隣接するＫ＋１スタンドと出側板幅を測定したより上流側にあるｋスタンドより下流にあり、かつより上流側の出側板幅を測定したスタンドＪとの間、出側板幅を測定したより下流側にあり、かつ出側板幅を測定したＪスタンドの下流に隣接するＪ＋１スタンドとより下流側にある出側板厚を測定したｍスタンドとの間、およびより下流側にある出側板厚を測定したｍスタンドの下流に隣接するｍ＋１スタンドと最終スタンドとの間により、それぞれスタンド区間が構成される。なお、この例では、ｍスタンドが最下流側の測定スタンドとなる。
【００４１】
この各スタンド区間の板幅変化量は、それぞれ、第１スタンド入側板幅と第Ｋスタンド出側板幅との差、第Ｋ＋１スタンド入側板幅すなわち第Ｋスタンド出側板幅と第Ｊスタンド出側板幅との差、第Ｊ＋１スタンドの入側板幅すなわち第Ｊスタンド出側板幅と第ｍスタンド出側板幅との差、第ｍ＋１スタンドと最終スタンド出側板幅との差、によって求められる。
【００４２】
このように、板幅を測定した圧延スタンドについて、その上流スタンドから下流側スタンドに向かって、逐次構成された各スタンド区間毎に上記測定結果から板幅変化量を算出することができる。一方、これらの測定スタンド間毎に板幅変化許容値を上述のように（８′）式により予め求めておくことができる。したがって、各スタンド間毎に板破断の可能性が大きく形状制御装置を操作すべきスタンドを特定し、各測定スタンド間毎に定めた位置幅変化許容値を超えないように、形状制御装置を制御する。
【００４３】
この説明においては、タンデム圧延機入側（第１圧延機入側）およびタンデム圧延機出側（最終圧延機出側）の他にタンデム圧延機間の３つのスタンドの出側において測定した例を示したが、これより少ないスタンド又は多いスタンドにおいて測定した場合も、上記の説明に準じて上流側から下流側に逐次スタンド間を構成し、形状制御装置を制御することができる。
【００４４】
なお、好ましくはたとえば４スタンドからなるタンデム圧延機の全スタンド間に板幅測定装置を設ければ、各スタンドの入側および出側の板幅変化の測定結果から第１〜４スタンドの板幅変化ΔＷ_lim （ｉ＝１〜４）が検出可能となり、第１〜４の各スタンド毎に設定した負側の許容値ΔＷ_lim ⁽¹⁾ 〜ΔＷ_lim ⁽⁴⁾ を超えないように形状制御装置４ａ〜４ｄを制御することによって、より高精度な板破断の防止制御が実現可能であることは言うまでもない。
【００４５】
また、タンデム圧延機のスタンド間に板幅測定装置がない場合でも、スタンド間に形状検出装置を有し、現状の各スタンドの板形状を計測あるいは推定できるような場合には、この形状検出値による板幅制御も実施可能である。すなわち、最も中伸び形状側となっているスタンドが板破断を生じる可能性が高いスタンドであるから、このスタンドから優先的に形状制御装置を操作する、例えば端伸び側に机上を変更することによって、板破断を防止することも可能である。
【００４６】
このように、タンデム圧延機の入・出側の板幅測定装置あるいは更に、スタンド間に備えた、板幅測定装置あるいは、形状測定装置に基づく板幅制御を併用することによって、板端部の張力が高く破断が生じやすいスタンドをより高精度に特定することが可能で、その特定したスタンドに対して板幅広がりを増大させる方向、すなわち端伸び側の圧延を行うことによって、板端に生じる過大張力を低減でき、全スタンドに渡って板破断の生じない圧延が可能となる。
【００４７】
なお、一般的に冷間タンデム圧延における板幅変化は、上記で述べたロールバイト近傍での変化がほとんどであり、この板幅変化量に基づき制御を行えば、実用的に十分な精度で板幅制御が実現可能であるが、圧延材の種類によっては、圧延機のスタンド間で板幅変化が生じる場合がある。その場合には、スタンド間での板幅変化量を測定あるいはその変化の要因であるスタンド間張力、温度、時間の変化から予測し求め、このスタンド間の板幅変化量を考慮に入れ、上述の板幅制御を行う必要がある。
【００４８】
また、板幅変化が板幅変化の許容値を超えない範囲では、出側板幅測定装置による板幅実測値を用いて、出側板幅が所定の目標板幅に一致するように、ロールベンダー制御あるいは張力制御を実施することができる。
このように、本発明を実施することによって、高い生産性を実現しながら、圧延材のヒートスクラッチと板破断の発生を同時に防止すると共に、製品板幅を一定にすることにより寸法精度の向上が期待できる。
【００４９】
【実施例】
〔実施例１〕
図１に示すようなそれぞれに形状制御装置を備えた第１〜第４スタンドを有し、かつ出側コイラーの出力が最終スタンドの主電動機の出力の５０％以上の出力を有し、圧延材の変形抵抗の３０％以上の張力を付加できる冷間タンデム圧延機において、これによって牛脂系の圧延潤滑油（４％エマルジョン）によるリサーキュレーション潤滑を行ないながら、厚み３mm、幅９００mmで材質が低炭素鋼の圧延材１を冷間圧延し、厚み０．８mmの鋼板ストリップを製造（圧延条件は冷間４スタンドタンデム圧延機の圧延条件として表２に示す）し、得られた鋼板ストリップにおいてヒートスクラッチの発生状況、板破断状況および板幅精度を調査した。
【００５０】
【表２】

【００５１】
なお、表２に示した従来例の張力条件の場合、第４スタンド出側でヒートスクラッチが発生しやすい状況にある。本発明の実施例１では、第１スタンド入側および第４スタンド出側には板幅測定装置６ａ，６ｅを設置し、第１〜４スタンド圧延機の形状制御装置４ａ〜４ｄを用いて、板幅制御ができるようにした。
先ず、第１スタンド入側および第４スタンド出側に板幅測定装置を有しない冷間タンデム圧延機による従来の場合、定常圧延状態に入ってから約１分後に、第１〜４スタンドの出側での非接触式の温度計（図示省略）を用いて板温度を測定した結果、第４スタンド出側の板温度が１８０℃になり、板破断は生じなかったが、ヒートスクラッチが第４スタンドで発生した。
【００５２】
また、上記の従来例において、第４スタンド出側の張力が変形抵抗値の４０％になるように張力条件だけを変更した場合では、第４スタンドでのヒートスクラッチの発生はなかったが、定常圧延状態に入ってから約２分後に第４スタンドで板破断が生じた。これは、張力条件だけの変更だけでは、ヒートスクラッチおよび板破断を同時に防止できないことを示している。また、この時の出側の板幅変動量をオフラインで測定した結果、±１〜３mmの変動があることがわかった。
【００５３】
一方、第１スタンド入側および第４スタンド出側に板幅測定装置６ａ，６ｅを設置した冷間タンデム圧延機による本発明の例では、検出板幅変化量ΔＷ^(1;4) が、式（８′）より求まるタンデム圧延機での許容値ΔＷ_lim ^(1;4) ＝ ２．５mmより板幅が減少したため、演算処理装置８内で、第ｉ＝１〜４スタンドの板端部の平均張力σ′⁽ⁱ⁾ を求め、その結果から、第４スタンド出側が最も板破断が生じやすいスタンドであることを特定し、第４スタンド出側の板幅を優先的に調整するように形状制御装置４ｄの操作量を設定し制御した。次いで上記と同じ方法で次に操作すべきスタンドを特定して制御する操作を繰り返し、板幅変化量ΔＷ^(1;4) が許容値ΔＷ_lim ^(1;4) より幅広がり側へ板幅が変化するまで、形状制御装置４ａ〜４ｄによる板幅制御を繰り返し実施した。
【００５４】
その結果、定常圧延状態に入ってから、第１〜４スタンドの出側で板温度計（図示省略）を用いて板温度を測定した結果、板温度は１６２℃〜１７５℃の範囲を維持されており、特に問題となった第４スタンドにおいてもヒートスクラッチ、板破断ともに発生しなかった。また、第４スタンド出側幅測定装置６ｅによる板幅の測定結果から、第４スタンド出側の板幅変動量は±１．０mm以下と減少していることがわかった。
【００５５】
このように、本発明を冷間タンデム圧延機に適用して、タンデム圧延機の入・出側に板幅測定装置６ａ，６ｅを配設して、形状制御装置４ａ〜４ｄで板幅制御することにより、特に問題となった第４スタンドでの摩擦発熱が減少し、ヒートスクラッチおよび板破断を防止することができると共に、製品板幅を一定にできることにより寸法精度の向上が図れることが検証された。
【００５６】
〔実施例２〕
次に、図２のような６スタンドから成る冷間タンデム圧延機に本発明を適用した場合について説明を行う。図２の冷間タンデム圧延機は、４段圧延機であり、ワークロール２ａ〜２ｆ、バックアップロール３ａ〜３ｆ、形状制御装置４ａ〜４ｆおよび演算処理装置８から構成されていて、タンデム圧延機の入側・出側には、入側・出側コイラー５ａ，５ｂが設置されている。出側コイラー５ｂは、最終スタンドの圧延機の主電動機の出力の３５％以上の出力があり、各スタンド間の張力は圧延材の変形抵抗の３０％〜４０％以上の圧延張力を付与可能である。また、タンデム圧延機の入側である第１スタンド入側、タンデム圧延機の出側である第６スタンド出側、およびタンデム圧延機の圧延機間として第３圧延機の出側の合計３箇所に、板幅測定装置６ａ，６ｇ，６ｄが設置され、また、第６スタンド出側には形状測定装置９が設置されている。表３に冷間６スタンドタンデム圧延機の圧延条件を示した。
【００５７】
【表３】

【００５８】
表３に示したように、第６スタンド出側の張力が変形抵抗値の４４％になるような圧延条件を設定し、牛脂系の圧延潤滑油（４％エマルジョン）によるリサーキュレーション潤滑を行いながら、厚み３mm、幅９００mmで材質が低炭素鋼の圧延材１を冷間圧延し、厚み０．４mmの薄手の鋼板ストリップを製造し、得られた鋼板ストリップにおいてヒートスクラッチの発生状況、板破断状況および板幅精度を調査した。
【００５９】
先ず、第１スタンド入側および第６スタンド出側に板幅測定装置６ａ，６ｇのみを用いて、実施例１と同様に、タンデム圧延機の入・出側の板幅測定値に基づく板幅制御を形状制御装置４ａ〜４ｆにおいて実施した場合、各スタンド出側のヒートスクラッチの発生はなく、正常に圧延が行われたが、板幅変動が±０．８〜１．４mmであることがわった。
【００６０】
次に、本発明の実施例２では、板幅測定装置６ａ，６ｄから第１〜３スタンド間の板幅変化量ΔＷ^(1;3) を、板幅測定装置６ｄ，６ｇから検出される第４〜６スタンド間の板幅変化量ΔＷ^(4;6) を求め、式（８′）より、第ｉ＝１〜３スタンド間の板幅変化の許容値ΔＷ_lim ^(1;3) ＝１．８mm、第ｉ＝４〜６スタンド間の板幅変化の許容値ΔＷ_lim ^(4;6) ＝−０．２mmを求め、実施例１と同様の方法で第ｉ＝１〜３スタンド間および第ｉ＝４〜６スタンド間のそれぞれで、板破断の可能性が大きく形状制御装置４ａ〜４ｆを操作すべきスタンドそれぞれ特定し、各許容値ΔＷ_lim ^(1;3) 、ΔＷ_lim ^(4;6) より板幅減少側へ板幅が変化しないように形状制御装置４ａ〜４ｆを板幅制御を実施した。
【００６１】
その結果、定常圧延状態に入ってから、第１〜６スタンドの出側で板温度計（図示省略）を用いて板温度を測定した結果、板温度は１６０℃〜１７４℃の範囲に維持されており、第１〜６スタンドでヒートスクラッチ、板破断ともに発生しなかった。また、この時の板幅変動量を、第６スタンド出側の出側幅測定装置６ｇによって測定した結果、±０．６mm以下であり、板幅精度は、実施例１の場合に比べて向上することがわかった。
【００６２】
この実施例２のように、タンデム圧延機の入側および出側の板幅測定値に加え、圧延機間の板幅測定が可能となり、入側および出側の板幅測定装置のみを用いた実施例１の場合に比べ、板幅変化の不明なスタンド数が減ることによって、より高精度な板幅制御が可能で、全スタンドに渡って、ヒートスクラッチおよび板破断の生じない圧延が可能となり、さらに、板幅精度も向上することが検証された。
【００６３】
なお、この実施例２の圧延機設備の場合、第６スタンド出側に形状測定装置９を有するので、この形状測定装置９による板形状検出値に基づき、第６スタンドにおいて形状制御装置４ｆによって、直接、張力分布を制御を実施することが可能だったので、この形状測定装置による制御と上述の板幅制御を併用することによって、より確実なヒートスクラッチおよび板破断防止制御が可能となった。
【００６４】
〔実施例３〕
本発明の有効性をさらに調査するために、実施例３では、図３に示すように実施例２と同様の６スタンドの冷間タンデム圧延機において、タンデム圧延機の各スタンドの前後に板幅測定装置６ａ〜６ｇ、第６スタンド出側に形状検出装置９を設置し、第１〜６の各スタンドで前後の板幅測定値に基づく板幅制御を実施した結果について説明する。なお、出側コイラー５ｂは、最終スタンドの圧延機の主電動機の出力の５０％以上の出力があり、実施例２の場合より、高張力圧延が実施可能となっている。
【００６５】
実施例２と同様に、牛脂系の圧延潤滑油（４％エマルジョン）によるリサーキュレーション潤滑を行いながら、厚み３mm、幅９００mmで材質が低炭素鋼の圧延材１を冷間圧延し、厚み０．４mmの薄手の鋼板ストリップを製造し、得られた鋼板ストリップにおいてヒートスクラッチの発生状況、板破断状況および板幅精度を調査した。なお、圧延条件は冷間６スタンドタンデムに圧延機の圧延条件（高速・高張力の場合）として表４に示した。表４に示したように、実施例２の条件より高速化・高張力化（第６スタンド出側の張力は変形抵抗値の５０％）している。
【００６６】
【表４】

【００６７】
本発明の実施例３では、各スタンドの前後の板幅測定装置６ａ〜６ｇから検出される第１〜６の各スタンドの板幅変化量ΔＷ⁽¹⁾ 〜ΔＷ⁽⁶⁾ のそれぞれが、第１〜６の各スタンド毎に設定した許容値ΔＷ_lim ⁽¹⁾ ＝０．５mm、ΔＷ_lim ⁽²⁾ ＝−０．２mm、ΔＷ_lim ⁽³⁾ ＝−０．５mm、ΔＷ_lim ⁽⁴⁾ ＝−０．５mm、ΔＷ_{li m} ⁽⁵⁾ ＝−０．７mm、ΔＷ_lim ⁽⁶⁾ ＝−０．８mmより板幅減少側に板幅が変化しないように、第１〜６の各スタンドの形状制御装置４ａ〜４ｆで繰り返し操作する板幅制御を実施した。
【００６８】
その結果、定常圧延状態に入ってから、第１〜６スタンドの出側で板温度計（図示省略）を、用いて板温度を測定した結果、板温度は、１６０℃〜１７０℃の範囲に維持されており、第１〜６の各スタンドでヒートスクラッチ、板破断ともに発生しなかった。また、この時の出側の板幅変動量を測定した結果、±０．５mm以下であることがわかった。
【００６９】
このように、タンデム圧延機の全てのスタンドの前後に板幅測定装置を設置することによって、全スタンドの板幅変化量の測定が可能で、確実に板端部の張力が推定可能となることから、高精度な板幅制御が実現でき、より高速化・高張力化した場合においても、全スタンドにおいて摩擦発熱が低減でき、ヒートスクラッチおよび板破断を防止することができると共に、製品板幅を一定にできることにより寸法精度の向上が図れることが検証された。
【００７０】
なお、上記実施例のように、板幅測定装置あるいは形状測定装置を増設する場合には、設備コスト増大が伴うので、効果とコストのバランスを考慮してスタンドを選択する。ただし、ヒートスクラッチと板破断の発生を同時に防止するためには、少なくとも最終スタンドでの適用は不可欠である。
【００７１】
【発明の効果】
本発明においては、４スタンド以上の圧延スタンドからなる冷間タンデム圧延機による鋼板の圧延に際して、従来例のようなコスト増、生産性低下を伴わずヒートスクラッチおよび板破断の発生を同時に防止することができ、板幅精度など品質の良好な鋼板を製造することができる。
【図面の簡単な説明】
【図１】本発明の実施例１の冷間タンデム圧延機設備を示す側面説明図。
【図２】本発明の実施例２の冷間タンデム圧延機設備を示す側面説明図。
【図３】本発明の実施例３の冷間タンデム圧延機設備を示す側面説明図。
【図４】形状制御装置の操作量の変化させて計算した場合のロールバイト前後の板幅変化を示す説明図。
【図５】形状制御装置の操作量の変化させて計算した場合のロールバイト出口における張力分布の変化を示す説明図。
【図６】板幅変化量と板端部の平均張力との関係を示す説明図。
【図７】圧延荷重比に及ぼす張力負荷比の影響を示す図。
【図８】耐摩耗性に及ぼす張力負荷比の影響を示す図。
【図９】表面欠陥発生率に及ぼす張力負荷比の影響を示す図。
【図１０】第１〜４スタンドの板幅変化の許容値を求める方法を示す図。
【符号の説明】
１…圧延材
２ａ〜２ｆ…第１〜６スタンドのワークロール
３ａ〜３ｆ…第１〜６スタンドのバックアップロール
４ａ〜４ｆ…第１〜６スタンドの形状制御装置
５ａ…入側コイラー
５ｂ…出側コイラー
６ａ…第１スタンド入側の板幅測定装置
６ｂ〜６ｇ…第１〜６スタンド出側の板幅測定装置
７ａ…入側ブライドルロール
７ｂ…出側ブライドルロール
８…演算処理装置
９…形状測定装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rolling equipment and a rolling method for realizing high productivity, reducing manufacturing costs, and improving dimensional accuracy in a cold tandem rolling mill having four or more cold rolling mills.
[0002]
[Prior art]
In order to increase the productivity of existing cold tandem rolling mills or to reduce the manufacturing cost thereof, methods such as increasing the rolling speed of the cold tandem rolling mills or optimizing the rolling schedule can be considered. It was.
When the rolling speed is increased, heat scratches are generated. The heat scratch is a seizure flaw caused by metal contact between a work roll and a rolled material, which is generated as a result of an increase in the interface temperature in the roll bite and an oil film breakage in the roll bite. When heat scratches occur, surface defects of the product occur, so that not only the product yield decreases, but also the work rolls of the rolling stand where the heat scratches have occurred need to be rearranged.
[0003]
As a conventional technique for preventing such heat scratches, for example, as disclosed in Japanese Patent Laid-Open No. 5-98283, a method using a rolling lubricant having excellent seizure resistance, or Japanese Patent Laid-Open No. 56-111505 is disclosed. In general, a method of reducing the temperature of a plate or a work roll by controlling the amount of coolant, as disclosed in JP-A-6-63624, or a method of reducing a rolling speed as disclosed in JP-A-6-63624 is generally used. is there.
[0004]
Further, as described above, as a method for preventing heat scratches without causing an increase in production cost and a decrease in productivity, such as the use of special rolling oil and a reduction in rolling speed, it is disclosed in JP-A-55-111961. As described, a reduction pattern setting method that minimizes the total rolling power consumed by rolling in a tandem rolling mill, and as disclosed in JP-A-60-49802, the tension between stands is increased, There is a method of preventing heat scratching by reducing the rolling pressure and reducing frictional heat generation.
[0005]
Conventionally, since fluctuations in sheet width in cold rolling are small compared to hot rolling, width meters are provided on the entrance and exit sides of the rolling mill as in hot rolling, and based on the output results of the width meters. Therefore, it has been rarely possible to actively control the plate width by changing the tension.
[0006]
[Problems to be solved by the invention]
However, in the case of the above-described conventional method of changing the reduction pattern, there is a problem that the plate accuracy is temporarily deteriorated, and in the case of the method of increasing the tension between the stands, the effect of preventing the heat scratch as the tension increases. However, on the other hand, because the tension level is high, the tension applied to the plate local part such as the plate edge due to the change in the tension distribution increases, so that the plate breaks easily, or the plate width becomes higher when the tension is increased. Since there is a problem that the plate width accuracy deteriorates due to large fluctuations, the conventional method has a limit in achieving both the effect of preventing heat scratching and the advantages of economy and productivity.
[0007]
As a method for increasing the inter-stand tension in the conventional method, the present inventors previously calculated the output of one outlet side coiler or the output of one outlet side coiler and the outlet side bridle roll by rolling the final stand. By making the output of the machine's main motor 35% or more or 50% or more, it becomes possible to realize high-tensile rolling with a rolling tension of 30% or more, preferably 40% or more of the deformation resistance of the rolled material in the final stand. Thus, a cold tandem rolling facility and a rolling method thereof have been proposed which can prevent occurrence of heat scratches and realize stable high-tensile rolling without breaking the plate.
[0008]
That is, the main cause of heat scratch generation in cold rolling is a temperature rise at the interface between the roll and the rolled material in the roll bite. This temperature rise is caused by work heat generation and friction heat generation. There is. When the rolling load decreases, the frictional heat generation decreases as the frictional heat generation decreases. Since the rolling load can be reduced by increasing the tension, increasing the tension lowers the interface temperature in the roll bite, which is an effective means for preventing heat scratches.
[0009]
Here, a tension load ratio κ (tension / deformation resistance of the rolled material), which is an index representing the level of tension on the entry side and exit side of the rolling stand, is defined. That is, the tension load ratio on the entry side and exit side of the rolling stand is_bAnd κ_fThen, the entry side tension σ in the rolling stand_bAnd outlet tension σ_fIs the 0.2% proof stress σ of the rolled material on the rolling stand entrance side and the exit side obtained from the tensile test of the rolled material_yiAnd σ_yoMultiplied by the aforementioned tension load ratio, that is, σ_b= Κ_bσ_yi, Σ_f= Κ_fσ_yoIt becomes. In the following description, when the tension load ratio or κ is described, the tension load ratio or κ is the tension load ratio κ on the entry side and the exit side of the rolling stand._bAnd κ_fBoth of them shall be included.
[0010]
FIG. 7 shows the influence of the tension load ratio κ on the rolling load ratio obtained from the experiment when the tension load ratio is changed [the rolling load at the time of tensionless rolling (κ = 0) is 1]. . FIG. 8 shows the amount of wear of the work roll under the same rolling conditions as shown in FIG. 7 (the weight of the work roll after being rotated about 100,000 times in a state where a load and slip are applied). The effect of the tension load ratio κ on the weight subtracted from the weight) [the amount of wear during tensionless rolling (κ = 0) is defined as wear resistance 1] is shown.
[0011]
7 and 8, it is clear that the larger the tension load ratio κ, the smaller the pressure and the contact arc length in the roll bite, and the greater the effect of the tension load ratio on the rolling load ratio and the wear resistance. became.
FIG. 9 shows the influence of the tension load ratio κ on the surface defect generation ratio of the product that occurs when heat scratching or the like occurs [the surface defect generation rate during tensionless rolling (κ = 0) is 1]. FIG. 9 reveals that the surface defect generation rate decreases as the tension load ratio κ increases, and surface defects do not occur when the tension load ratio κ is about 0.3.
[0012]
From the above, the tension load ratio κ is 0.3 or more, preferably 0.4 or more, that is, the tension is 30% or more, preferably 40% or more of the deformation resistance of the rolling material at the entrance and exit of the rolling stand. It is intended to load the inlet and outlet tensions. As a result, it is possible to perform rolling that does not generate heat scratches and the like, and it is possible to reduce rolling load and to perform rolling that ensures wear resistance that can maintain the roughness of the work roll surface for a long period of time.
[0013]
The tension load ratio may be set for each stand as described above, but only the rolling stand where heat scratches or the like are likely to occur may be set. In particular, in the final rolling stand where the rolling speed is the fastest, heat scratches and the like are likely to occur. Therefore, at least in the final rolling stand, the tension load ratio κ can be set to 0.3 or more, preferably 0.4 or more. desirable.
[0014]
Next, a cold tandem rolling mill for realizing the rolling method described above will be described. With existing tandem rolling mills, rolling speeds at the normal operating level (1000 to 2000 m · min^-1), Since the output of the main motor of one coiler on the final stand exit side is small, the tension level on the final stand exit side cannot be increased. At present, the output of one outlet coiler or the total of the main motors of one outlet coiler and outlet bridle roll is a heavy system in which products with a thickness of 0.6 mm or more account for 50% or more of the total production. In cold tandem rolling mills, the output of the main motor of the final stand rolling mill is 47% or less, and thin products with a product thickness of less than 0.6 mm account for 50% or more of the total production. In the intermediate tandem rolling mill, it is 32% or less of the output of the main motor of the rolling mill in the final stand. Therefore, in the case of rolling low carbon steel, the tension level on the exit side of the final stand is usually 5-10 kgf · mm.^-2Degree. In the case of low carbon steel, deformation resistance is 60 to 70 kgf · mm due to work hardening in the vicinity of the final stand.^-2Therefore, the tension level is a low value of about 7 to 17% of the deformation resistance.
[0015]
Therefore, in order to make the tension load ratio κ 0.3 or more, preferably 0.4 or more in the final rolling stand, the output of the main motor of the final stand and the output of the main motor of the coiler system or the coiler system and the bridle roll The total output of the main motor needs to be optimized. For this purpose, it is first necessary to obtain the work performed by the rolling mill and the coiler system, that is, the work performed by the coiler alone or the coiler and the bridle roll.
[0016]
Therefore, work W that the coiler system does_cWork W that the rolling mill does in unit time_MCompare the ratios.
Work W done by rolling mill per unit time_MIs represented by (1).
W_M= TV₀/ {R (1 + f_S)} (1)
Where R is the roll radius, V₀Is the exit side plate speed of the rolling stand, T is the rolling torque (for two upper and lower rolls), for example, calculated from the Hill equation, f_SIs an advanced rate, and is calculated using, for example, the formula of Bland & Ford.
[0017]
Also, a coiler system, that is, a coiler alone or a work W performed by a coiler and a bridle roll._cIs represented by equation (2).
W_c= V₀κσ_yh'b (2)
Here, h ′ is the exit side plate thickness, b is the plate width, σ_yIs 0.2% proof stress, and the strain ε in the following formula (3) is obtained with 0.002.
σ_y(Ε) = a (ε + ε₀)ⁿ                                    (3)
Where a, ε₀, N are constants, and are determined from the results of a tensile test performed in advance.
[0018]
Table 1 shows the work W made by the coiler_cWork W that the rolling mill does in unit time_MThe typical calculation result which calculated and compared is shown.
[0019]
[Table 1]

[0020]
In Table 1, the rolling conditions of the thin stand for rolling the product plate thickness to less than 0.6 mm and the thick stand for rolling the product plate thickness to 0.6 mm or more were assumed. However, the constant of the expression (3) representing the deformation resistance is a value obtained in advance by a tensile test, a = 67 kgf · mm.^-2, Ε₀= 0.03, n = 0.2, and the friction coefficient was a typical friction coefficient μ = 0.05 obtained under normal rolling conditions in the final stand of cold rolling. The roll radius R in Table 1 is a typical roll radius used in the final stand of a normal cold tandem rolling mill, and the rolling reduction r, rolling load P, work roll speed V_RMaterial thickness H_ThreeIs a value in a range of typical rolling conditions in ordinary cold tandem rolling.
[0021]
As described above, in order to perform stable cold tandem rolling, the tension negative addition ratio κ needs to be 0.3 or more. For that purpose, Table 1 (the work W performed by the coiler system per unit time)_OAnd the work W done by the last stand rolling mill per unit time_MThe ratio of. As can be seen from the figure, the coiler work is 50% or more of the work of the rolling mill of the final stand in a cold tandem mill that produces a product with a product thickness of 0.6 mm. It can be seen that a cold tandem mill that produces thin 2 mm products requires over 35% of the work of the final stand mill. That is, the output of the coiler main motor is 50% or more of the main motor of the final stand rolling mill in a cold tandem rolling mill producing a product with a product thickness of 0.6 mm, and the product thickness is 0. A cold tandem mill that produces 2 mm thin products requires 35% or more of the output of the main motor of the final stand mill.
[0022]
  Instead of generating a large tension only with the outlet coiler, a bridle roll for tension load may be installed between the final stand and the outlet coiler in consideration of the coiler switching. In this case, the sum of the output of one outlet coiler and the outlet bridle roll only needs to satisfy the above condition. The parameter average thickness h[Mm]Using the above, the sum of the output of the main motor of one outlet coiler or the output of the main motor of the outlet bridle roll of one outlet coiler is expressed as W_c , W output of the main motor of the final stand rolling mill_M WhenW_c ≧ (0.375h + 0.275) W_M It can be seen that a cold tandem rolling mill of [kW] is required.
[0023]
At that time, as described above, the total rolling tension (the value obtained by multiplying the rolling tension by the plate thickness and the plate width) is set to the same value on the entrance side and the exit side of the rolling mill, thereby causing an excessive load (mechanism loss) on the rolling mill. It is preferable to make the total rolling tension equal on the entrance and exit sides of the rolling mill.
As described above, the output of one outlet coiler or the output of one outlet coiler and the outlet bridle roll should be 35% or more or 50% or more of the output of the main motor of the rolling mill at the final stand. Thus, it is possible to realize high-tensile rolling that applies a rolling tension of 30% or more, preferably 40% or more of the deformation resistance of the rolled material in the final stand, thereby preventing occurrence of heat scratches.
[0024]
However, when the tension is 30% to 40% or more of the deformation resistance, the tensile stress level at the end of the plate increases, so that the plate breaks easily. In particular, when a note rim material is rolled, minute cracks are likely to occur at the end of the plate, so that the plate breakage is more likely to occur. Therefore, in order to prevent heat scratching and sheet breakage at the same time, high tension rolling with a tension of 30% to 40% or more of deformation resistance is performed, and excessive tension at the end of the sheet is applied. It is necessary to control the tension distribution to prevent plate breakage.
[0025]
[Means for Solving the Problems]
The present invention is for solving the problems of the conventional methods as described above,
Claim 1 of the present invention is a cold tandem rolling mill having four or more cold rolling mills equipped with a shape control device, and measures the sheet width of the rolled material on the entry side and the exit side of the tandem rolling mill. Calculate the amount of change in the width of the tandem rolling mill at the entry and exit sides from the measured value of the plate width, and control the shape control device so that this change in the plate width does not exceed the predetermined allowable change in the plate width The cold tandem rolling method is characterized in that rolling is performed with a rolling tension of 30% or more of the deformation resistance of the rolled material at least in the final stand.
[0026]
Claim 2 is a cold tandem rolling mill having four or more cold rolling mills equipped with a shape control device, wherein at least one of the rolling mills between the inlet side, the outlet side of the tandem rolling mill and the tandem rolling mill Measure the width of the rolled material on the exit side,
Between the first stand of the tandem rolling mill and the stand on the upstream side of the outlet plate width measured between the tandem rolling mill and the stand adjacent to the downstream of the stand on the upstream side of the outlet plate width measured. A stand adjacent to the downstream of the stand on the downstream side where the width of the outlet plate is measured, and the downstream of the stand on the most downstream side where the outlet plate width is measured. A stand section is constructed sequentially between the final stand and
From the above measurement results, the plate width change amount is calculated for each stand section, so that the plate width change amount of the stand section does not exceed the plate width change allowance predetermined for each stand section. In this rolling method, the control device is controlled and rolling is performed with a rolling tension of at least 30% of the deformation resistance of the rolled material.
[0027]
Claim 3 is a cold tandem rolling mill having four or more cold rolling mills equipped with a shape control device, in which the strip width of the rolled material on the entry side of the tandem rolling mill and on the exit side of each rolling mill of the tandem rolling mill From this measured value of the plate width, the amount of change in the width of the entry side and the exit side of each rolling mill of the tandem rolling mill is calculated. The shape control device is controlled so that it does not exceed the predetermined allowable value of the change in sheet width on the side and the exit side, and at least the final stand is rolled with a tension of 30% or more of the deformation resistance of the rolled material. Is a cold tandem rolling method.
[0028]
  A fourth aspect of the present invention is a cold tandem rolling mill having four or more cold rolling mills each provided with a shape control device in each stand, and plate width measuring devices are provided at least on the entry side and the exit side of the tandem rolling mill.A coiler or a coiler and a bridle roll on the outlet side of the cold tandem rolling mill. The output of the main motor of this coiler, or the output of the main motor of the coiler and the main motor of the bridle roll The total output of the output, the output of the main motor of the final stand of the cold tandem rolling mill, and the average sheet thickness of products rolled by this cold tandem rolling mill satisfy the following relationship:This is a cold tandem rolling mill.
[0029]
W _c ≧ (0.375h + 0.275) W _M
However, W _c : The output of the main motor of one coiler, or the total output of the output of the main motor of one coiler and the output of the main motor of the bridle roll
W _M : Output of the main motor of the final stand of the cold tandem rolling mill
h: Average plate thickness [mm] of products rolled by a cold tandem rolling mill
[0030]
  A fifth aspect of the present invention is the cold tandem rolling mill according to the fourth aspect, wherein the cold tandem rolling mill has a sheet width measuring device at least at one position between the rolling mills of the cold tandem rolling mill.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Then, next, the present invention controls the tension distribution by measuring and controlling the plate width to prevent the plate from breaking. Hereinafter, the method of the present invention will be described.
First, regarding the mechanism of sheet width change, which is the basic principle of the present invention, a sheet rolling analysis system (analysis system that combines sheet deformation analysis by a three-dimensional rigid-plastic FEM and general-purpose roll deformation analysis by a division model) ) Will be described based on the knowledge obtained from the analysis results.
[0032]
FIGS. 4 and 5 show the vicinity of the roll bite, the inside of the roll bite, the roll when calculated by changing the rolling mill shape control device (here, the work roll bending device is provided and the roll bending force is changed). The change of the board width in the vicinity of a bite exit and the change of the tension of the width direction in a roll bite exit are shown. Here, the three areas near the roll bite entrance, within the roll bite, and near the roll bite exit are simply expressed as the roll bite vicinity. From these figures, when a bending force is applied to the decrease side (the shape is the end extension side: F <0), the amount of spread in the vicinity of the roll bite increases, and the tension distribution is 100 mm from the plate end. It can be seen that the tension in a certain area is reduced. On the other hand, when a bending force is applied to the increase side (the shape is the middle extension side: F> 0), the plate width decreases near the roll bite, and the tension distribution is from the end of the plate. It can be seen that the tension in the region of about 100 mm increases. As described above, the plate width change in the vicinity of the roll bite tends to decrease (width shrinkage) as the plate end tension increases, and increase (widen) as the plate end tension decreases.
L from the edge_eIf the average tension at the end of the sheet in the range of 50 mm is σ ′ and the change in sheet width in the vicinity of the roll bite is ΔW, the relationship between σ ′ and ΔW can be expressed by the relationship shown in FIG. Contact arc length l_d). Therefore, the plate width change amount ΔW in the vicinity of the roll tool is σ ′, l_dAs a function of
ΔW = ΔW (σ ′, l_d(4)
Further, the average tension σ ′ of the plate end portion is the rolling condition, that is, the roll bending force F, the average tension σ per unit sectional area of the stand entrance side and exit side._b, Σ_f, Outlet side thickness h ', plate width W, contact arc length l_dAnd can be expressed as the following equation as these functions.
σ ′ = σ ′ (F, σ_b, Σ_f, H ′, W, l_d(5)
Thus, since there is a relationship as shown in equations (4) and (5) in the plate width change, the plate end tension, and the rolling conditions (roll bending force, average tension, etc.), in the present invention, the plate width Is used as a detection end, and the fluctuation of the tension is replaced with the fluctuation of the plate width, and the plate width is controlled, thereby preventing the heat scratch and the plate breakage. That is, the average tension σ ′ = σ ′ at the end of the plate that does not cause plate breakage_limThen σ ′_limThe allowable plate width change ΔW from the equation (4)_lim, And observe the change in the plate width and allow the change in the plate width ΔW_limThe plate width control amount is determined so as not to cause a reduction in the plate width that exceeds A, and based on this plate width control amount, the roll bending force F or the input / exit side average tension is determined as the operation amount of the shape control device from Equation (5). σ_b, Σ_fAnd controlling based on this, it is possible to prevent plate breakage caused by excessive tension applied to the plate end. Note that the average tension σ ′ at the end of the limit plate_limIs smaller than the breaking stress of the rolled material obtained in advance by a tensile test (5 to 10 kgf · mm^-2It is preferable to set a smaller value. Further, in this control, it is preferable to maintain the high productivity by changing the tension distribution in the width direction by manipulating the roll bending force or the like, rather than reducing the entry / exit tension.
[0033]
In order to simplify the explanation in equation (5), only the bending force in the roll bending device is considered as the shape control device, but the operation amount of the roll cross device, the roll axial direction shift device, and the roll profile control device is It is possible to obtain a relationship with the plate width change amount, obtain a plate width change amount that is equal to or less than a predetermined tension, and control the tension including the tension distribution so as to be equal to or less than the width change amount. It goes without saying that several of these shape control devices can be used in combination to control the tension, and these shape control devices can be used in place of the roll bending force.
[0034]
Next, the present invention will be described in detail with reference to FIG. FIG. 1 shows a cold tandem rolling mill having four stands, in which a rolled material 1 is rolled. The rolling mill of each stand is a four-high rolling mill, and includes a four-high rolling mill provided with work rolls 2a to 2d, backup rolls 3a to 3d, and shape control devices 4a to 4d, and an arithmetic processing unit 8. . An inlet side coiler 5a, an outlet side coiler 5b, an inlet side plate width measuring device 6a and an outlet side plate width measuring device 6b are installed on the inlet side and the outlet side of the tandem rolling mill.
[0035]
In the cold tandem rolling mill of the present invention, as shown in FIG. 1, it may be provided at least on the entry side and the exit side of the tandem cold rolling mill, but as will be described later, between any stands of the tandem rolling mill Also preferably provided.
In this example, the main motor of the exit side coiler 5b has an output of 50% or more of the output of the main motor of the rolling mill of the final stand, and the tension between the stands is 30 of the deformation resistance of the rolling material. It is possible to roll with a rolling tension of% to 40% or more.
[0036]
In such a cold tandem rolling mill, the rolled material 1 is rolled with a tension of 30% to 40% or more of the deformation resistance of the rolled material, and the sheet width is on the entry side and the exit side of the tandem rolling mill. From measuring devices 6a and 6e, plate width W of rolled material 1⁽⁰⁾, W^(Four)(Where (0) indicates the tandem rolling mill entry side and (4) indicates the number of the rolling stand). In the arithmetic processing unit 8, the detected plate width W on the entry side / exit side of the tandem rolling mill⁽⁰⁾, W^(Four)From the first to fourth (represented as 1; 4), the cumulative value of the sheet width change in the stand rolling mill, that is, the sheet width change amount in the entire tandem rolling mill is ΔW.^{(1; 4)}Then, ΔW^{(1; 4)}Is calculated from the following equation.
ΔW^{(1; 4)}= W^(Four)-W⁽⁰⁾(+: Increase in plate width,-: decrease in plate width) (6)
Moreover, this is generally expressed by the following equation when expressed as a case of a rolling mill of the nth to Nth (represented as n; N, hereinafter the same) stand.
ΔW^{(n; N)}= W^(N)-W^(n-1)                                  (6 ')
However, ΔW^{(n; N)}: Cumulative sheet width change between rolling mills of the nth to Nth stands, W^(n-1): Nth stand entry side plate width, W^(N): Nth stand exit side width
This plate width change amount ΔW^{(1; 4)}However, the allowable value ΔW on the negative side (sheet width reduction side) that may cause sheet breakage in the tandem rolling mill_lim ^{(1; 4)}If it exceeds, the plate width correction amount ΔW to be corrected in the tandem rolling mill_c ^{(1; 4)}For example, the correction amount to the plate width increasing side is calculated as follows.
ΔW_c ^{(1; 4)}= ΔW^{(1; 4)}-ΔW_lim ^{(1; 4)}                        (7)
Moreover, when this is generally expressed as a case of a rolling mill of the nth to Nth stands, it is expressed by the following formula.
ΔW_c ^{(n; N)}= ΔW^{(n; N)}-ΔW_lim ^{(n; N)}                      (7 ')
However, ΔW_c ^{(n; N)}: Sheet width correction amount in rolling mills of nth to Nth stands, ΔW_lim ^{(n; N)}: Allowable value of plate width change in rolling mills of nth to Nth stands
In addition, allowable value ΔW in tandem rolling mill_lim ^{(1; 4)}Is, for example, the allowable value ΔW of the plate width change amount of the i-th stand obtained from Equation (4)._lim ⁽ⁱ⁾(I = 1 to 4), plate width change ΔW of i-th stand⁽ⁱ⁾Assuming that (i = 1 to 4), as shown in FIG. 10, ΔW at any stand in the tandem rolling mill⁽ⁱ⁾-ΔW_lim ⁽ⁱ⁾If it changes only, there is a possibility of causing plate breakage.⁽ⁱ⁾-ΔW_lim ⁽ⁱ⁾The allowable value ΔW for the entire tandem rolling mill with reference to the minimum value of_lim ^{(1; 4)}Is calculated as:
ΔW_lim ^{(1; 4)}= ΔW^{(1; 4)}−min (ΔW⁽ⁱ⁾-ΔW_lim ⁽ⁱ⁾) (I = 1 to 4) (8)
However, min () represents the minimum value in the i-th to 1-4th stands.
Moreover, when this is generally expressed as a case of a rolling mill of the nth to Nth stands, it is expressed by the following formula.
ΔW_lim ^{(n; N)}= ΔW^{(n; N)}−min (ΔW⁽ⁱ⁾-ΔW_lim ⁽ⁱ⁾) (I = n to N) (8 ')
This plate width correction amount ΔW_c ^{(1; 4)}Based on the above, by identifying the stand where the plate breakage may occur in the first to fourth stands, and adjusting the bending force or shift amount by the stand shape control device, the plate width is controlled preferentially. Break prevention control can be realized. Note that the control amount such as bending force and shift amount of the shape control device is the plate width correction amount ΔW._c ^{(1; 4)}Depending on the above, the calculation is performed from the equations (4) and (5). By the way, in the case of this example, since the plate width measuring device is not provided between the stands in the tandem rolling mill, the stand to be controlled by the shape control device is specified and controlled by the following method, for example.
[0037]
In other words, roll bending force F of i = 1 to 4 stands⁽ⁱ⁾, Average tension σ per unit cross-sectional area on the entrance side and exit side of the stand_b ⁽ⁱ⁾ , Σ_f ⁽ⁱ⁾, Outboard thickness h '⁽ⁱ⁾, Contact arc length l_d ⁽ⁱ⁾Is determined from the set values and measured values of the current rolling conditions, and the average tension at the plate end of the i-th stand is expressed as σ ′ from Equation (5).⁽ⁱ⁾(I = 1 to 4) is estimated. σ ′⁽ⁱ⁾Since the highest stand has a high possibility of plate breakage, this stand is identified as the jth stand to be controlled. In this case, in Formula (5), the absolute value W of the plate width on the exit side of each stand⁽ⁱ⁾Is required, but the width change ΔW of each stand⁽ⁱ⁾Is the plate width W⁽ⁱ⁾Board width W⁽ⁱ⁾Is approximated to be constant at each stand. Board width correction amount of the jth stand ΔW_c ⁽ⁱ⁾ΔW_c ⁽ⁱ⁾= ΔW_c ^{(1; 4)}From the equations (4) and (5), the operation amount F of the shape control device of the jth stand_c ⁽ⁱ⁾Is calculated. This manipulated variable F_c ⁽ⁱ⁾Based on the above, the shape control device of the jth stand is operated. After the operation, similarly, the average tension at the plate end of the i = 1 to 4th stand is represented by σ ′.⁽ⁱ⁾(I = 1 to 4) is obtained, the jth stand to be controlled next is specified, the operation amount of the shape control device of the jth stand is set, and the plate width change amount ΔW^{(1; 4)}Is the negative tolerance ΔW_lim ^{(1; 4)}The control by the shape control devices 4a to 4d is repeatedly performed until the following.
[0038]
Further, as described above, in addition to the plate width measuring devices on the entry and exit sides of the tandem rolling mill, a plate width measuring device is provided between the kth and k + 1th stands (1 ≦ k <4) in the tandem rolling mill. The plate width change ΔW between i = 1 to k stands and between i = k + 1 to 4 stands.^{(1; k)}And ΔW^{((k + 1); 4)}And the allowable value ΔW of the plate width change between the i-th to 1-k stands from the 8th equation._lim ^{(1; k)}, The allowable value ΔW of plate width change between i = k + 1 to 4th stand_lim ^{((k + 1); 4)}In the same manner as described above, each of the stands where the shape control devices 4a to 4d are to be operated is identified between the i = 1 to k stands and between the i = k + 1 to 4 stands with a large possibility of plate breakage. And each allowable value ΔW_lim ^{(1; k)}, ΔW_lim ^{((k + 1); 4)}The shape control devices 4a to 4d are controlled so as not to exceed. In this case, the plate width can be controlled with higher accuracy by reducing the number of stands whose plate width change is unknown due to an increase in the plate width measuring device as compared with the above case.
[0039]
In addition, the tandem rolling mill has an inlet side of the first rolling mill and an outlet side of the final rolling mill of the tandem rolling mill, and any one or more rolling mills between the tandem rolling mills, for example, k stands from the upstream side, k The example of measuring the plate width on the exit side of the j stand downstream from the stand and the m stand further downstream from the stand will be described with respect to the rolling stand between the tandem rolling mills measuring the exit plate width from the upstream side to the downstream side. As shown in FIG.
[0040]
That is, adjacent between the first stand of the tandem rolling mill and the K stand on the upstream side of the outlet plate width measured between the tandem rolling mill and the downstream of the K stand on the upstream side of the outlet plate width measured. Between the K + 1 stand to be measured and the stand K which is upstream from the upstream side where the outlet side plate width is measured, and from the stand J which has measured the outlet side plate width at the upstream side, the downstream side from which the outgoing side plate width is measured. In addition, between the J + 1 stand adjacent to the downstream of the J stand where the exit side plate width was measured and the m stand where the exit side plate thickness was measured further downstream, and the m stand where the exit side plate thickness was measured further downstream A stand section is formed between the m + 1 stand adjacent to the downstream and the final stand. In this example, the m stand is the most downstream measurement stand.
[0041]
The amount of change in the plate width of each stand section is the difference between the first stand entry side plate width and the Kth stand exit side plate width, the (K + 1) th stand entry side plate width, that is, the K stand exit side plate width and the J stand exit side plate width. And the difference between the inlet side plate width of the (J + 1) th stand, that is, the difference between the Jth stand outlet side plate width and the mth stand outlet side plate width, and the difference between the (m + 1) th stand and the final stand outlet side plate width.
[0042]
Thus, about the rolling stand which measured the board width, the board width variation | change_quantity can be calculated from the said measurement result for every stand area comprised sequentially from the upstream stand toward a downstream stand. On the other hand, the plate width change allowable value can be obtained in advance by the equation (8 ′) as described above for each of these measurement stands. Therefore, the stand where the shape control device is highly likely to be broken between each stand is specified, and the shape control device is controlled so as not to exceed the allowable position width change value determined between each measurement stand. To do.
[0043]
In this description, in addition to the tandem rolling mill inlet side (first rolling mill inlet side) and the tandem rolling mill outlet side (final rolling mill outlet side), an example is measured on the outlet side of three stands between tandem rolling mills. Although shown, even when measuring with fewer or more stands, it is possible to sequentially configure the stands from the upstream side to the downstream side and control the shape control device in accordance with the above description.
[0044]
Preferably, for example, if a plate width measuring device is provided between all the stands of a tandem rolling mill consisting of four stands, the plate widths of the first to fourth stands are determined from the measurement results of the change in the plate width on the entry side and the exit side of each stand. Change ΔW_lim(I = 1 to 4) can be detected, and the negative tolerance ΔW set for each of the first to fourth stands._lim ⁽¹⁾~ ΔW_lim ^(Four)It goes without saying that more accurate prevention control of the plate breakage can be realized by controlling the shape control devices 4a to 4d so as not to exceed.
[0045]
In addition, even if there is no plate width measuring device between the stands of the tandem rolling mill, if there is a shape detection device between the stands and the current plate shape of each stand can be measured or estimated, this shape detection value It is also possible to implement plate width control. That is, since the stand that is the most stretched shape side is a stand that is highly likely to cause plate breakage, the shape control device is operated preferentially from this stand, for example, by changing the desktop to the end stretch side It is also possible to prevent plate breakage.
[0046]
Thus, by using together the plate width measuring device on the entry / exit side of the tandem rolling mill or the plate width measuring device provided between the stands, or the plate width control based on the shape measuring device, It is possible to specify a stand with high tension and easy breakage with higher accuracy, and it is generated at the end of the plate by rolling in the direction of increasing the width of the plate with respect to the specified stand, that is, rolling on the end extension side. Excessive tension can be reduced, and rolling can be performed without causing plate breakage over the entire stand.
[0047]
In general, the plate width change in the cold tandem rolling is mostly the change in the vicinity of the above-mentioned roll bite. If control is performed based on the amount of change in the plate width, the plate width is practically sufficiently accurate. Although width control is realizable, depending on the kind of rolling material, a plate | board width change may arise between the stands of a rolling mill. In that case, the amount of plate width change between stands is measured or predicted from the changes in tension, temperature, and time between the stands, which are the factors of the change, and the amount of plate width change between stands is taken into account. It is necessary to control the plate width.
[0048]
In addition, in the range where the change in the plate width does not exceed the allowable value of the change in the plate width, the roll bender control is performed so that the output side plate width matches the predetermined target plate width using the actual plate width measured by the output side plate width measuring device. Alternatively, tension control can be implemented.
In this way, by implementing the present invention, while realizing high productivity, the occurrence of heat scratch and rolling of the rolled material is prevented at the same time, and the dimensional accuracy is improved by making the product plate width constant. I can expect.
[0049]
【Example】
[Example 1]
1 has first to fourth stands each having a shape control device as shown in FIG. 1, and the output of the outlet coiler has an output of 50% or more of the output of the main motor of the final stand, In a cold tandem rolling mill that can apply a tension of 30% or more of the deformation resistance, recirculation lubrication with beef tallow-based rolling lubricant (4% emulsion), while the material is 3mm thick and 900mm wide. The rolled steel 1 is cold-rolled to produce a steel strip having a thickness of 0.8 mm (the rolling conditions are shown in Table 2 as the rolling conditions of a cold 4-stand tandem rolling mill), and the obtained steel strip is heated. The occurrence of scratches, plate breakage and plate width accuracy were investigated.
[0050]
[Table 2]

[0051]
In the case of the conventional tension conditions shown in Table 2, heat scratches are likely to occur on the fourth stand exit side. In Example 1 of the present invention, the plate width measuring devices 6a and 6e are installed on the first stand entry side and the fourth stand exit side, and using the shape control devices 4a to 4d of the first to fourth stand rolling mills, The board width can be controlled.
First, in the conventional case of a cold tandem rolling mill that does not have a sheet width measuring device on the first stand entry side and the fourth stand exit side, the first to fourth stand exits approximately one minute after entering the steady rolling state. As a result of measuring the plate temperature using a non-contact thermometer (not shown) on the side, the plate temperature on the fourth stand exit side was 180 ° C., and no plate breakage occurred, but the heat scratch was the fourth. Occurs at the stand.
[0052]
Further, in the above conventional example, when only the tension condition was changed so that the tension on the fourth stand outlet side was 40% of the deformation resistance value, no heat scratch was generated in the fourth stand. About 2 minutes after entering the rolled state, the plate broke at the fourth stand. This shows that heat scratching and plate breakage cannot be prevented at the same time only by changing the tension condition alone. Moreover, as a result of measuring the amount of fluctuation of the width of the delivery side on the off-line at this time, it was found that there was a fluctuation of ± 1 to 3 mm.
[0053]
On the other hand, in the example of the present invention by the cold tandem rolling mill in which the plate width measuring devices 6a and 6e are installed on the first stand entry side and the fourth stand exit side, the detected plate width change amount ΔW^{(1; 4)}Is the allowable value ΔW in the tandem rolling mill obtained from the equation (8 ′)_lim ^{(1; 4)}= Since the plate width has decreased from 2.5 mm, the average tension σ ′ of the plate end portions of the i = 1 to 4th stands in the arithmetic processing unit 8⁽ⁱ⁾From the result, it is determined that the fourth stand exit side is the stand that is most likely to break, and the operation amount of the shape control device 4d is adjusted so as to preferentially adjust the plate width on the fourth stand exit side. Set and controlled. Next, the operation for identifying and controlling the stand to be operated next by the same method as above is repeated, and the plate width change amount ΔW^{(1; 4)}Is the allowable value ΔW_lim ^{(1; 4)}The plate width control by the shape control devices 4a to 4d was repeatedly performed until the plate width changed to the wider side.
[0054]
As a result, after entering the steady rolling state, the plate temperature was measured using a plate thermometer (not shown) on the exit side of the first to fourth stands. As a result, the plate temperature was maintained in the range of 162 ° C to 175 ° C. Neither the heat scratch nor the plate breakage occurred in the fourth stand, which was particularly problematic. Further, from the measurement result of the plate width by the fourth stand exit side width measuring device 6e, it was found that the amount of fluctuation in the plate width on the fourth stand exit side decreased to ± 1.0 mm or less.
[0055]
As described above, the present invention is applied to a cold tandem rolling mill, and the plate width measuring devices 6a and 6e are arranged on the inlet / outlet side of the tandem rolling mill, and the plate width is controlled by the shape control devices 4a to 4d. As a result, it has been verified that frictional heat generation at the fourth stand, which has been particularly problematic, can be reduced, heat scratching and plate breakage can be prevented, and that the product plate width can be made constant, thereby improving dimensional accuracy. It was.
[0056]
[Example 2]
Next, the case where this invention is applied to the cold tandem rolling mill which consists of 6 stands like FIG. 2 is demonstrated. The cold tandem rolling mill of FIG. 2 is a four-high rolling mill, which is composed of work rolls 2a to 2f, backup rolls 3a to 3f, shape control devices 4a to 4f, and an arithmetic processing unit 8, On the entry / exit side, entry / exit side coilers 5a and 5b are installed. The exit side coiler 5b has an output of 35% or more of the output of the main motor of the rolling mill of the final stand, and the tension between the stands can apply a rolling tension of 30% to 40% or more of the deformation resistance of the rolled material. is there. Also, a total of three locations on the first stand entry side that is the entry side of the tandem rolling mill, the sixth stand exit side that is the exit side of the tandem rolling mill, and the exit side of the third rolling mill as the rolling mills of the tandem rolling mill In addition, plate width measuring devices 6a, 6g and 6d are installed, and a shape measuring device 9 is installed on the exit side of the sixth stand. Table 3 shows the rolling conditions of a cold 6 stand tandem rolling mill.
[0057]
[Table 3]

[0058]
As shown in Table 3, the rolling conditions were set so that the tension on the exit side of the sixth stand was 44% of the deformation resistance value, and recirculation lubrication was performed with beef tallow-based rolling lubricant (4% emulsion). However, the rolled material 1 with a thickness of 3 mm and a width of 900 mm is cold-rolled to produce a thin steel strip with a thickness of 0.4 mm. The situation and board width accuracy were investigated.
[0059]
First, using only the plate width measuring devices 6a and 6g on the first stand entry side and the sixth stand exit side, as in Example 1, the plate width based on the measured plate width values on the entry and exit sides of the tandem rolling mill When control was performed in the shape control devices 4a to 4f, there was no occurrence of heat scratches on the exit side of each stand, and the rolling was performed normally, but the plate width variation was ± 0.8 to 1.4 mm. Wow.
[0060]
Next, in Embodiment 2 of the present invention, the plate width change amount ΔW between the first to third stands from the plate width measuring devices 6a and 6d.^{(1; 3)}, The plate width change amount ΔW between the fourth to sixth stands detected from the plate width measuring devices 6d and 6g.^{(4; 6)}From the equation (8 ′), the allowable value ΔW of the plate width change between i = 1 to 3 stands_lim ^{(1; 3)}= 1.8 mm, i = 4 to 6 tolerance of change in plate width between stands 6W_lim ^{(4; 6)}= −0.2 mm, the shape control devices 4a to 4f have a high possibility of plate breakage in the same manner as in Example 1 between i = 1 to 3 stands and i = 4 to 6 stands. Each stand to be operated, and each allowable value ΔW_lim ^{(1; 3)}, ΔW_lim ^{(4; 6)}The shape control devices 4a to 4f were subjected to plate width control so that the plate width did not change further toward the plate width reduction side.
[0061]
As a result, after entering the steady rolling state, as a result of measuring the plate temperature using a plate thermometer (not shown) on the exit side of the first to sixth stands, the plate temperature is maintained in the range of 160 ° C to 174 ° C. Neither heat scratch nor plate breakage occurred in the first to sixth stands. Moreover, as a result of measuring the board width fluctuation amount at this time by the exit side width measuring device 6g on the sixth stand exit side, it is ± 0.6 mm or less, and the board width accuracy is improved as compared with the case of the first embodiment. I found out that
[0062]
As in Example 2, in addition to the measured values of the sheet width on the entry side and the exit side of the tandem rolling mill, it becomes possible to measure the sheet width between the rolling mills, and only the sheet width measuring devices on the entry side and the exit side were used. Compared to the case of Example 1, by reducing the number of stands whose plate width change is unknown, more accurate plate width control is possible, and it is possible to perform rolling without causing heat scratches and plate breaks over all stands. Furthermore, it was verified that the plate width accuracy was also improved.
[0063]
In the case of the rolling mill equipment of Example 2, since the shape measuring device 9 is provided on the sixth stand exit side, based on the plate shape detection value by the shape measuring device 9, the shape control device 4f in the sixth stand Since it was possible to directly control the tension distribution, more reliable heat scratch and plate breakage prevention control became possible by using the control by the shape measuring device and the above-described plate width control in combination.
[0064]
Example 3
In order to further investigate the effectiveness of the present invention, in Example 3, as shown in FIG. 3, in a 6-stand cold tandem rolling mill similar to that in Example 2, the plate width before and after each stand of the tandem rolling mill A description will be given of results obtained by installing the shape detection device 9 on the exit side of the measurement devices 6a to 6g and the sixth stand, and performing plate width control based on the front and rear plate width measurement values in the first to sixth stands. In addition, the exit side coiler 5b has an output of 50% or more of the output of the main motor of the rolling mill of the final stand, and can perform high tension rolling compared to the case of the second embodiment.
[0065]
Similarly to Example 2, while performing recirculation lubrication with beef tallow rolling lubricant (4% emulsion), cold rolling was performed on a rolled material 1 having a thickness of 3 mm, a width of 900 mm, and a low-carbon steel, and having a thickness of 0 A thin steel strip having a thickness of 4 mm was manufactured, and the resulting steel strip was examined for the occurrence of heat scratch, the state of plate breakage, and the plate width accuracy. The rolling conditions are shown in Table 4 as the rolling conditions of the rolling mill (in the case of high speed and high tension) in a cold 6 stand tandem. As shown in Table 4, the speed and tension were increased from the conditions of Example 2 (the tension on the sixth stand exit side was 50% of the deformation resistance value).
[0066]
[Table 4]

[0067]
In Embodiment 3 of the present invention, the plate width change amount ΔW of each of the first to sixth stands detected from the plate width measuring devices 6a to 6g before and after each stand.⁽¹⁾~ ΔW⁽⁶⁾Is the allowable value ΔW set for each of the first to sixth stands._lim ⁽¹⁾= 0.5mm, ΔW_lim ⁽²⁾= -0.2mm, ΔW_lim ⁽³⁾= -0.5mm, ΔW_lim ^(Four)= -0.5mm, ΔW_{li m} ^(Five)= -0.7mm, ΔW_lim ⁽⁶⁾The plate width control was repeatedly performed by the shape control devices 4a to 4f of the first to sixth stands so that the plate width did not change to the plate width decreasing side from −0.8 mm.
[0068]
As a result, after entering the steady rolling state, the plate temperature was measured using a plate thermometer (not shown) on the exit side of the first to sixth stands. As a result, the plate temperature was in the range of 160 ° C to 170 ° C. It was maintained, and neither heat scratch nor plate breakage occurred in each of the first to sixth stands. Further, as a result of measuring the amount of fluctuation in the width of the exit side at this time, it was found that it was ± 0.5 mm or less.
[0069]
In this way, by installing the plate width measuring device before and after all the stands of the tandem rolling mill, it is possible to measure the amount of change in the plate width of all the stands, and to reliably estimate the tension at the end of the plate. Therefore, highly accurate plate width control can be realized, and even when the speed and tension are increased, frictional heat generation can be reduced in all stands, heat scratches and plate breakage can be prevented, and the product plate width can be reduced. It was verified that the dimensional accuracy can be improved by making it constant.
[0070]
Note that, when the plate width measuring device or the shape measuring device is added as in the above embodiment, the equipment cost is increased, so the stand is selected in consideration of the balance between the effect and the cost. However, in order to prevent the occurrence of heat scratch and plate breakage at the same time, it is indispensable at least for the final stand.
[0071]
【The invention's effect】
In the present invention, at the time of rolling a steel sheet by a cold tandem rolling mill comprising four or more rolling stands, simultaneously preventing the occurrence of heat scratches and sheet breakage without increasing costs and reducing productivity as in the conventional example. It is possible to manufacture a steel plate with good quality such as plate width accuracy.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory side view showing cold tandem rolling mill equipment according to Embodiment 1 of the present invention.
FIG. 2 is an explanatory side view showing cold tandem rolling mill equipment according to a second embodiment of the present invention.
FIG. 3 is an explanatory side view showing cold tandem rolling mill equipment according to Embodiment 3 of the present invention.
FIG. 4 is an explanatory diagram showing a change in the plate width before and after a roll tool when calculated by changing the operation amount of the shape control device.
FIG. 5 is an explanatory diagram showing a change in tension distribution at the roll bite outlet when calculation is performed by changing the operation amount of the shape control device.
FIG. 6 is an explanatory diagram showing the relationship between the amount of change in plate width and the average tension at the end of the plate.
FIG. 7 is a diagram showing the influence of a tension load ratio on a rolling load ratio.
FIG. 8 is a graph showing the influence of a tension load ratio on wear resistance.
FIG. 9 is a diagram showing the influence of the tension load ratio on the surface defect occurrence rate.
FIG. 10 is a view showing a method for obtaining an allowable value of a change in the plate width of the first to fourth stands.
[Explanation of symbols]
1 ... Rolled material
2a to 2f: Work rolls for the first to sixth stands
3a to 3f ... backup rolls of the first to sixth stands
4a to 4f: Shape control device for first to sixth stands
5a ... Entrance coiler
5b ... Outside coiler
6a ... Plate width measuring device on the first stand entry side
6b-6g ... 1st-6th stand exit side board width measuring device
7a ... Entry side bridle roll
7b ... Outside bridle roll
8: Arithmetic processing device
9. Shape measuring device

Claims (5)

  In a cold tandem rolling mill having four or more cold rolling mills equipped with a shape control device, the sheet width of the rolled material is measured on the entry side and the exit side of the tandem rolling mill, and tandem rolling is performed from the sheet width measurement value. The amount of change in sheet width on the in-feed side and the exit side is calculated, and the shape control device is controlled so that this amount of change in sheet width does not exceed the predetermined allowable value of change in sheet width, and at least at the final stand A cold tandem rolling method comprising rolling with a rolling tension of 30% or more of the deformation resistance of the material. In a cold tandem rolling mill having four or more cold rolling mills equipped with a shape control device, rolled material on the inlet side, the outlet side of the tandem rolling mill, and the outlet side of at least one stand between the tandem rolling mills Measure the board width of
Between the first stand of the tandem mill and the stand on the upstream side where the exit side plate width was measured between the tandem mill, and the stand adjacent to the downstream of the stand on the upstream side where the exit side plate width was measured A stand adjacent to a stand downstream of the stand on the upstream side where the width of the side plate is measured and a stand on the downstream side of the outlet plate where the width of the outgoing side plate is measured, and downstream of the stand on the most downstream side where the width of the outlet plate is measured. A stand section is constructed sequentially between the final stand and
From the above measurement results, the plate width change amount is calculated for each stand section, so that the plate width change amount of the stand section does not exceed the plate width change allowance predetermined for each stand section. A cold tandem rolling method comprising controlling a control device and rolling at least a rolling tension of 30% or more of a deformation resistance of a rolled material. In a cold tandem rolling mill having four or more cold rolling mills equipped with a shape control device,
The sheet width of the rolled material is measured on the entry side of the tandem rolling mill and on the delivery side of each rolling mill of the tandem rolling mill, and the sheet width on the entry side and the exit side of each rolling mill of the tandem rolling mill is determined from this sheet width measurement value. While calculating the amount of change, and controlling the shape control device so that these plate width change amount does not exceed the predetermined allowable value of the plate width change amount on the entry side and the exit side of each rolling mill of the tandem rolling mill, respectively A cold tandem rolling method comprising rolling at least 30% of the deformation resistance of the rolled material at least in the final stand. A tandem cold rolling mill having a respective stand shape control device 4 stand more cold rolling mill provided with a, have a sheet width measuring device to at least the entry side and exit side of the tandem rolling mill, cold A coiler or a coiler and a bridle roll are provided on the exit side of the tandem rolling mill, and the output of the main motor of one coiler or the total output of the output of the main motor of the coiler and the main motor of the bridle roll A cold tandem rolling mill characterized in that the output of the main motor of the final stand of the cold tandem rolling mill and the average plate thickness of the product rolled by the cold tandem rolling mill satisfy the following relationship:
W _c ≧ (0.375h + 0.275) W _M
However, W _c : The output of the main motor of one coiler, or the total output of the output of the main motor of one coiler and the output of the main motor of the bridle roll
W _M : Output of the main motor of the final stand of the cold tandem rolling mill
h: Average plate thickness [mm] of products rolled by a cold tandem rolling mill   The cold tandem rolling mill according to claim 4, further comprising a sheet width measuring device at least at one location between the rolling mills of the cold tandem rolling mill.

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