JP3767832B2 - Thickness control method in hot rolling - Google Patents

Thickness control method in hot rolling Download PDF

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Publication number
JP3767832B2
JP3767832B2 JP19364195A JP19364195A JP3767832B2 JP 3767832 B2 JP3767832 B2 JP 3767832B2 JP 19364195 A JP19364195 A JP 19364195A JP 19364195 A JP19364195 A JP 19364195A JP 3767832 B2 JP3767832 B2 JP 3767832B2
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Japan
Prior art keywords
rolling
control
thickness
transformation point
mill
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JP19364195A
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Japanese (ja)
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JPH0938708A (en
Inventor
信夫 福井
茂 木原
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Nippon Steel Corp
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Nippon Steel Corp
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Description

【0001】
【発明の属する技術分野】
本発明は、熱間圧延における板厚制御方法に関するものである。
【0002】
【従来の技術】
近年、圧延製品の厚み精度に対する要求は益々厳しくなっている。これに対してストリップの長手方向の厚み精度は自動板厚制御の急速な発達によって、高い制御効果を挙げている。この自動板厚制御(AGC)としては、例えば特公昭61−29807号公報に掲げているように、(1)入側の板厚の変化を圧延荷重の変化として検出し、この検出された荷重変化に対応してロールの圧下量を調整する方法(いわゆるゲージメータ方式のAGC)。(2)入側の板厚の変化を圧延機入側に取付けられた厚み計により検出し、この検出された厚み変化を用いて圧下制御量を求め、被圧延材の速度より圧延機位置に到達したことを検出し圧延機の圧下量を調整する方法(フィードフォワード)。(3)出側の板厚の変化を圧延機出側に取付けられた厚み計により検出し、この検出された厚み変化により比例積分制御により圧下量を調整する方法(モニターAGCあるいはフィードバックAGC)がある。
【0003】
これらの方法の改良として、検出された圧延機入側の板厚を目標値に合致させるに必要な制御量あるいはその制御量に相当する圧延荷重を求め、圧延機に設置された圧延荷重検出手段の出力あるいはその出力に相当する制御量を求め、これら2つの圧延荷重あるいは制御量を用いて板厚調整手段に出力する制御量を演算し、この演算値により板厚調整手段を制御することが開示されている。
【0004】
【発明が解決しようとする課題】
上述した特公昭61−29807号公報は圧延機出側の板厚を目標値に制御する圧延機の自動板厚制御方法の一つではあるが、しかし、この自動板厚制御方法には制御ゲインについては何ら触れられていない。また、変更するとしても材料単位での変更であり、この各材料単位毎に一定値での制御で圧延するのが通常である。しかし、圧延材は温度によって塑性係数は異なるもので、この各材料単位毎での制御圧延では必ずしも精度の良い、しかも適正な制御量にはならないという問題がある。
【0005】
【課題を解決するための手段】
本発明は、上述したような問題を解消し、圧延材のAr3変態点の温度を予測して、このAr3変態点を境として材料の塑性係数を考慮した板厚制御ゲインを変更した板厚制御を行う熱間圧延における板厚制御方法を提供するものである。
その発明の要旨とするところは、
(1)仕上圧延機内での材料長手方向の温度を予測し、圧延材のAr3変態点の温度を予測演算し、Ar3変態点を境にしてAr3変態点より高い部分と低い部分で板厚制御ゲインを変更するに当たり、仕上圧延機のいずれか1スタンドのロールギャップを固定し、入側板厚変動とミル剛性と荷重変動から材料の塑性係数を求め、初期設定された塑性係数との比率を求め、該比率を以降の各スタンド毎の初期設定の塑性係数に掛けて板厚制御ゲインを変更し板厚を制御することを特徴とする熱間圧延における板厚制御方法にある。
【0006】
以下本発明について図面に従って詳細に説明する。
図1は粗圧延機と仕上圧延機が連続して配置された連続熱間圧延機群の概略図である。図1に示すように、圧延材1を送り込み、粗圧延機2群R1 〜R6 によって仕上圧延機に送り込むために、適当な板厚の圧延材に圧延し、更にこの圧延材は仕上圧延機3群の一番目の圧延機(F1 スタンド)から順次連続的に圧延を行っていき、7番目の圧延機(F7 スタンド)出側にて所定の厚みの圧延製品が得られるようになっている。このような連続式圧延機群において、温度計4は粗圧延機出側及び仕上圧延機入側並びに仕上圧延機の中間に温度計をそれぞれ配置し、各温度計4は温度演算器5に取込み、仕上圧延機入側と粗圧延機出側の温度計を使用する場合には、これらを用いて仕上圧延機F1 〜F7 の圧延時の長手方向の温度を予測する。
【0007】
また、中間圧延温度計の場合は中間圧延温度計以降のスタンドの圧延時の長手方向の温度を予測する。この場合、温度予測については、一般的には空冷、ロール接触、デスクーリング、ロール冷却水及び加工発熱を考慮して設計する必要がある。特に、ここでは長さ方向に連続的に温度を予測することに特徴がある。
一方、仕上圧延機には板厚計6を配設し、圧延中に板厚制御装置7は板厚計6の検出値と基準板厚との偏差を入側板厚偏差として算出し出側において目標板厚を確保する必要な圧下制御量を制御演算装置9を介して圧下装置8に出力する。
【0008】
このように仕上圧延機内での材料長手方向の温度を予測するものであるが、圧延材のAr3 変態点温度において、極端に材料塑性係数が変化する。すなわち、圧延材のAr3 変態点は鋼種によって異なり、特に炭素に影響し、極低炭素鋼の場合には変態点が上がり、仕上圧延出側温度、例えば、900℃でAr3 変態点があり、この温度以下において変態が起こり極端に材料塑性係数が小さくなる。特に炭素が低いと変態点温度が上がり、仕上圧延中に起こるものである。そこで、極端に塑性係数が変化するAr3 変態点を境としてAr3 変態点より高い部分と低い部分とに区分して変態挙動をモデル化し、熱間仕上圧延中にモデルに基づいて所定の変態率パターンに沿って板厚制御ゲインを変更する必要がある。
【0009】
図2は本発明に係るゲイン変更の方法を示すブロック図である。この図に示すように、ゲージメータ板厚偏差を求め、PI制御によりゲイン変更するに当たり、初期設定ミル剛性Ms、初期設定の材料塑性係数Qsと逐次変化する圧延荷重に対するミル剛性M及び実際の圧延中の塑性係数Qとの間に{Ms/(Ms+Qs)}/{M/(M+Q)}の比を求め、このQをAr3変態点を切ったときに変更させるもので、圧延中に変化する荷重に対し刻々とミル剛性を計算し、ロールギャップ量を操作出力させるものである。この場合に図3に示すように温度に対応してゲインを変更し、更にAr 3 変態点近くではゲインを極端に変更する操作を行う。即ち、図3は圧延機通過予測温度とゲインとの関係を示す図である。
【0010】
図4は本発明に係る他の実施例であるゲイン変更の方法を示すブロック図である。仕上圧延機のいずれか1スタンドのロールギャップを固定して、実際の圧延中の塑性係数Qを測定する方法を示す。荷重変化△Fは次の式で表すことが出来る。
△F=MQ/(M+Q)×△H−MQ/(M+Q)×△S
ただし、△H:入側板厚変化
△S:ロールギャップ変化
AGCを停止すれば、△Sの項は0にして、誤差を小さくすることが出来る。
従って、△F=MQ/(M+Q)×△Hが成立する。この場合に△Hはゲージメータ板厚で推定計算するか、あるいは板厚検出を設置して実測する。この式をQの式に変形すると、
Q=△F×M/(M×△H−△F)で求めることが出来る。
【0011】
このようにして、塑性係数Qは圧延中に連続的に計算して求める。なお、図4のQLはロックオン時のQを意味し、それにある定数kを掛けて操作出力とする。勿論、図2の構成にしてもよい。このように、予め初期設定された塑性係数QLとの比率を求め、この比率を以降のスタンド毎の初期設定された塑性係数に掛けて板厚制御ゲイン変更板厚を制御するものである。
【0012】
【発明の効果】
以上述べたように、本発明による、圧延材のAr3 変態点の温度を予測し、このAr3 変態点を境として圧延材料の塑性係数を考慮した板厚制御ゲインを変更した板厚制御を行うことにより、従来に比較して板厚偏差の極めて少ない板厚制度の高い自動板厚制御を実現することが出来た。
【図面の簡単な説明】
【図1】粗圧延機と仕上圧延機が連続して配置された連続熱間圧延機群の概略図、
【図2】本発明に係るゲイン変更の方法を示すブロック図、
【図3】圧延機通過予測温度とゲインとの関係を示す図、
【図4】本発明に係る他の実施例であるゲイン変更の方法を示すブロック図である。
【符号の説明】
1 圧延材
2 粗圧延機
3 仕上圧延機
4 温度計
5 温度演算器
6 板厚計
7 板厚制御装置
8 圧下装置
9 制御演算装置
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet thickness control method in hot rolling.
[0002]
[Prior art]
In recent years, the demand for thickness accuracy of rolled products has become increasingly severe. On the other hand, the thickness accuracy in the longitudinal direction of the strip has a high control effect due to the rapid development of automatic plate thickness control. As this automatic plate thickness control (AGC), for example, as disclosed in Japanese Patent Publication No. 61-29807, (1) a change in the plate thickness on the inlet side is detected as a change in rolling load, and this detected load A method (so-called gauge meter type AGC) of adjusting the amount of roll reduction corresponding to the change. (2) A change in the sheet thickness on the entry side is detected by a thickness meter attached to the entry side of the rolling mill, and the reduction control amount is obtained using the detected thickness change, and the rolling mill position is determined from the speed of the material to be rolled. A method of detecting the arrival and adjusting the rolling reduction of the rolling mill (feed forward). (3) There is a method (monitor AGC or feedback AGC) in which a change in sheet thickness on the delivery side is detected by a thickness meter attached to the delivery side of the rolling mill and the reduction amount is adjusted by proportional integral control based on the detected thickness change. is there.
[0003]
As an improvement to these methods, a rolling load detection means installed in the rolling mill is obtained by obtaining a control amount necessary for matching the detected sheet thickness on the entry side of the rolling mill to the target value or a rolling load corresponding to the control amount. Or the control amount corresponding to the output is calculated, the control amount output to the plate thickness adjusting means is calculated using these two rolling loads or control amounts, and the plate thickness adjusting means is controlled by this calculated value. It is disclosed.
[0004]
[Problems to be solved by the invention]
Japanese Patent Publication No. 61-29807 described above is one of the automatic sheet thickness control methods of a rolling mill that controls the sheet thickness on the delivery side of the rolling mill to a target value. However, this automatic sheet thickness control method has a control gain. There is no mention about. Moreover, even if it changes, it is a change by a material unit, and it is normal to roll by control by a fixed value for every each material unit. However, the rolled material has a different plastic coefficient depending on the temperature, and there is a problem that the controlled rolling for each material unit does not always have a high precision and an appropriate control amount.
[0005]
[Means for Solving the Problems]
The present invention eliminates the above-described problems, predicts the temperature of the Ar 3 transformation point of the rolled material, and changes the thickness control gain considering the plastic coefficient of the material at the Ar 3 transformation point as a boundary. The present invention provides a sheet thickness control method in hot rolling that performs thickness control.
The gist of the invention is that
(1) Predicting the temperature in the longitudinal direction of the material in the finishing mill, predicting and calculating the temperature of the Ar 3 transformation point of the rolled material, and using the Ar 3 transformation point as a boundary, the part higher and lower than the Ar 3 transformation point When changing the plate thickness control gain, fix the roll gap of any one of the finishing mills, find the plastic coefficient of the material from the inlet side plate thickness fluctuation, mill rigidity and load fluctuation, and set the initial plastic coefficient. The present invention provides a sheet thickness control method in hot rolling, characterized in that a ratio is obtained, the ratio is multiplied by an initial plastic coefficient for each stand, and a sheet thickness control gain is changed to control the sheet thickness.
[0006]
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view of a continuous hot rolling mill group in which a rough rolling mill and a finish rolling mill are continuously arranged. As shown in FIG. 1, in order to feed the rolled material 1 and feed it into the finishing mill by the rough rolling mills 2 groups R 1 to R 6 , the rolled material 1 is rolled into a rolled material having an appropriate thickness. Rolling is performed sequentially from the first rolling mill (F 1 stand) of the three groups of mills, so that a rolled product with a predetermined thickness can be obtained at the outlet side of the seventh rolling mill (F 7 stand). It has become. In such a group of continuous rolling mills, the thermometer 4 is arranged in the middle of the roughing mill exit side, the finishing mill entry side, and the finishing mill, and each thermometer 4 is taken into the temperature calculator 5. When using the thermometers on the finishing mill entry side and the roughing mill exit side, the temperature in the longitudinal direction during the rolling of the finish rolling mills F 1 to F 7 is predicted using them.
[0007]
In the case of an intermediate rolling thermometer, the temperature in the longitudinal direction during rolling of the stand after the intermediate rolling thermometer is predicted. In this case, the temperature prediction generally needs to be designed in consideration of air cooling, roll contact, desking, roll cooling water, and processing heat generation. In particular, the characteristic here is that the temperature is predicted continuously in the length direction.
On the other hand, a plate thickness meter 6 is provided in the finishing mill, and during rolling, the plate thickness control device 7 calculates the deviation between the detected value of the plate thickness meter 6 and the reference plate thickness as the inlet side plate thickness deviation, and on the output side. A necessary reduction control amount for ensuring the target plate thickness is output to the reduction device 8 via the control arithmetic device 9.
[0008]
Thus, the temperature in the longitudinal direction of the material in the finishing mill is predicted, but the material plasticity coefficient changes extremely at the Ar 3 transformation point temperature of the rolled material. That is, the Ar 3 transformation point of the rolled material varies depending on the steel type, and particularly affects carbon. In the case of extremely low carbon steel, the transformation point rises and there is an Ar 3 transformation point at the finish rolling exit temperature, for example, 900 ° C. Below this temperature, transformation occurs and the material plasticity coefficient becomes extremely small. In particular, if carbon is low, the transformation point temperature rises and occurs during finish rolling. Therefore, extreme plasticity coefficient is divided into a varying Ar 3 lower and higher than the Ar 3 transformation point to transformation point as a boundary portion partially modeling the transformation behavior, the predetermined transformation on the basis of the model during hot finish rolling It is necessary to change the plate thickness control gain along the rate pattern.
[0009]
FIG. 2 is a block diagram showing a gain changing method according to the present invention. As shown in this figure, when the gauge meter thickness deviation is obtained and the gain is changed by PI control, the initial setting mill rigidity Ms, the initial setting material plasticity coefficient Qs, the mill rigidity M with respect to the rolling load that sequentially changes, and the actual rolling obtains the ratio {Ms / (Ms + Qs) } / {M / (M + Q)} between the plastic coefficient Q in, the Q one which changes when you turn off the Ar 3 transformation point, change during rolling The mill rigidity is calculated for each load, and the roll gap amount is output as an operation. In this case, as shown in FIG. 3, the gain is changed according to the temperature, and further , an operation for changing the gain extremely near the Ar 3 transformation point is performed. That is, FIG. 3 is a diagram showing a relationship between rolling mill passage predicted temperature and gain.
[0010]
FIG. 4 is a block diagram showing a gain changing method according to another embodiment of the present invention. A method of measuring the plastic coefficient Q during actual rolling by fixing the roll gap of any one stand of a finishing mill will be described . The load change ΔF can be expressed by the following equation.
ΔF = MQ / (M + Q) × ΔH−MQ / (M + Q) × ΔS
However, ΔH: Change in entry side plate thickness ΔS: If the roll gap change AGC is stopped, the term ΔS can be set to 0 to reduce the error.
Therefore, ΔF = MQ / (M + Q) × ΔH is established. In this case △ H is measured by installing or estimated calculated by the gauge meter thickness, or the thickness detector a. When this equation is transformed into the equation of Q,
Q = ΔF × M / (M × ΔH−ΔF).
[0011]
In this way, the plastic coefficient Q is obtained by continuously calculating during rolling. Note that QL in FIG. 4 means Q at the time of lock-on, and is multiplied by a constant k to obtain an operation output. Of course, the configuration of FIG. 2 may be used. In this manner, the ratio with the plastic coefficient QL that is preset in advance is obtained , and the ratio is multiplied by the plastic coefficient that is initially set for each subsequent stand to change the sheet thickness control gain to control the sheet thickness. .
[0012]
【The invention's effect】
Above As I mentioned, according to the present invention, to predict the temperature of the Ar 3 transformation point of the rolled material, the gauge control for changing the gauge control gain considering the plasticity coefficient of rolling material as a boundary the Ar 3 transformation point By doing so, it was possible to realize automatic plate thickness control with a plate thickness system with extremely small plate thickness deviation compared to the conventional one.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a group of continuous hot rolling mills in which a rough rolling mill and a finishing rolling mill are continuously arranged.
FIG. 2 is a block diagram showing a gain changing method according to the present invention;
FIG. 3 is a diagram showing the relationship between rolling mill passage predicted temperature and gain;
FIG. 4 is a block diagram showing a gain changing method according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rolled material 2 Coarse rolling mill 3 Finish rolling mill 4 Thermometer 5 Temperature calculator 6 Plate thickness meter 7 Plate thickness control device 8 Reduction device 9 Control calculation device

Claims (1)

仕上圧延機内での材料長手方向の温度を予測し、圧延材のAr3変態点の温度を予測演算し、Ar3変態点を境にしてAr3変態点より高い部分と低い部分で板厚制御ゲインを変更するに当たり、仕上圧延機のいずれか1スタンドのロールギャップを固定し、入側板厚変動とミル剛性と荷重変動から材料の塑性係数を求め、初期設定された塑性係数との比率を求め、該比率を以降の各スタンド毎の初期設定の塑性係数に掛けて板厚制御ゲインを変更し板厚を制御することを特徴とする熱間圧延における板厚制御方法。Predicts the temperature in the longitudinal direction of the material in the finish rolling mill, predicts and calculates the temperature of the Ar 3 transformation point of the rolled material, and controls the thickness of the part higher and lower than the Ar 3 transformation point with the Ar 3 transformation point as a boundary. When changing the gain, fix the roll gap of any one of the finishing mills, calculate the plastic coefficient of the material from the inlet side thickness fluctuation, mill rigidity and load fluctuation, and obtain the ratio with the initially set plastic coefficient. A sheet thickness control method in hot rolling, wherein the sheet thickness control gain is changed by multiplying the ratio by an initial plastic coefficient for each subsequent stand to control the sheet thickness.
JP19364195A 1995-07-28 1995-07-28 Thickness control method in hot rolling Expired - Fee Related JP3767832B2 (en)

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JP3767832B2 true JP3767832B2 (en) 2006-04-19

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KR100376475B1 (en) * 1998-12-29 2003-07-16 주식회사 포스코 Prediction of thickness shrinkage during cooling after rolling
JP5610776B2 (en) * 2010-01-14 2014-10-22 株式会社神戸製鋼所 Method for determining control gain in rolling mill and rolling mill
CN113042538A (en) * 2021-03-03 2021-06-29 首钢京唐钢铁联合有限责任公司 Control method and device for rolling deviation of hot rolled strip steel

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