JP7052671B2

JP7052671B2 - Metal band temperature control method and temperature control device

Info

Publication number: JP7052671B2
Application number: JP2018197171A
Authority: JP
Inventors: 真二木村; 知義小笠原; 洋明佐々木; 隆之福井
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2018-10-19
Filing date: 2018-10-19
Publication date: 2022-04-12
Anticipated expiration: 2038-10-19
Also published as: JP2020063497A

Description

本発明は、金属帯の温度制御方法及び温度制御装置に関する。 The present invention relates to a metal band temperature control method and a temperature control device.

一般に、連続焼鈍後の金属帯は、冷却帯においてガスジェットを用いて目標温度となるように冷却される。溶融金属めっき鋼板を製造する際には、めっき浴中に侵入する金属帯の温度が目標温度管理範囲を外れると、不めっき、冷却ムラ、さざ波と呼ばれる表面欠陥不良を発生させてしまうため、金属帯の温度を厳密に管理する必要がある。このため、溶融金属めっきの前工程である焼鈍に続く冷却帯における金属帯の温度制御精度を向上させることは重要であり、特許文献１～３には操業条件が変更された場合の高精度な温度制御方法が提案されている。 Generally, the metal band after continuous annealing is cooled to a target temperature by using a gas jet in the cooling zone. When manufacturing hot-dip metal-plated steel sheets, if the temperature of the metal band invading the plating bath deviates from the target temperature control range, non-plating, uneven cooling, and surface defect defects called ripples will occur. It is necessary to strictly control the temperature of the band. Therefore, it is important to improve the temperature control accuracy of the metal band in the cooling zone following the annealing, which is the pre-process of hot metal plating, and Patent Documents 1 to 3 describe the high accuracy when the operating conditions are changed. A temperature control method has been proposed.

具体的には、特許文献１には、ライン速度や板厚等の操業条件が変更された場合、変更後の操業条件をパラメータとして含むモデル式を用いてめっき浴へ侵入する前の特定位置での金属帯の目標温度を算出し、操業条件変更時又は一定の時間間隔毎に新たな目標温度を設定することによって温度制御の精度及び応答性を改善する技術が記載されている。 Specifically, in Patent Document 1, when the operating conditions such as the line speed and the plate thickness are changed, a model formula including the changed operating conditions as a parameter is used at a specific position before entering the plating bath. A technique for improving the accuracy and responsiveness of temperature control by calculating the target temperature of the metal band and setting a new target temperature when the operating conditions are changed or at regular time intervals is described.

また、特許文献２には、ライン速度や板厚等の操業条件が変更された場合、モデル式を用いてプレナムチャンバ圧力(ガスジェット圧力)の変更量を予め計算しておき、溶接点が所定の場所に到達した時点でプレナムチャンバ圧力を変更することにより、操業条件の変更に伴う金属帯の温度変動を改善する技術が記載されている。 Further, in Patent Document 2, when the operating conditions such as the line speed and the plate thickness are changed, the change amount of the plenum chamber pressure (gas jet pressure) is calculated in advance using a model formula, and the welding point is predetermined. A technique for improving the temperature fluctuation of the metal band due to the change of operating conditions by changing the plenum chamber pressure at the time of reaching the place of is described.

さらに、特許文献３には、操業条件の変更時等の過渡期において、板厚測定値やライン速度の変更量及び変化率等をパラメータとして用いて、金属帯の温度が目標温度に収束した際に安定すべきブロワ回転数の定常解を予め演算してブロワ回転数指令値とするフィードフォワード制御の技術が記載されている。 Further, in Patent Document 3, when the temperature of the metal band converges to the target temperature by using the measured value of the plate thickness, the change amount of the line speed, the rate of change, etc. as parameters in the transitional period such as when the operating conditions are changed. Describes a feed-forward control technique in which a steady solution of a blower rotation speed to be stable is calculated in advance and used as a blower rotation speed command value.

特開２００５－２９８９０号公報Japanese Unexamined Patent Publication No. 2005-29890 特開昭６１－２５７４２４号公報Japanese Unexamined Patent Publication No. 61-257424 特開２００５－２２０４３２号公報Japanese Unexamined Patent Publication No. 2005-220432

特許文献１に記載の技術は、操業条件が変更された場合、金属帯の特定位置での目標温度を再計算して変更し、冷却帯で冷却制御を行うことによって浴侵入板温度を変えてめっき浴の温度を制御し、温度制御の応答性を改善している。しかしながら、特許文献１に記載の技術では、制御量はフィードバック制御によって出力されるものであり、金属帯の温度を測定することを前提としているため、応答に遅れが生じる。すなわち、特許文献１に記載の技術によれば、フィードバック制御出力は大きくなるものの、金属帯の温度が徐々に目標温度となるような制御をしているため、ライン速度が変化する過渡期においては、目標温度外れが発生する。このため、応答速度が必ずしも十分であるとはいえない。 The technique described in Patent Document 1 recalculates and changes the target temperature at a specific position of the metal band when the operating conditions are changed, and changes the bath penetration plate temperature by performing cooling control in the cooling zone. The temperature of the plating bath is controlled to improve the responsiveness of temperature control. However, in the technique described in Patent Document 1, the controlled variable is output by feedback control, and it is premised that the temperature of the metal band is measured, so that a delay occurs in the response. That is, according to the technique described in Patent Document 1, although the feedback control output is large, the control is performed so that the temperature of the metal band gradually reaches the target temperature, so that in the transitional period when the line speed changes, , Target temperature deviation occurs. Therefore, it cannot be said that the response speed is always sufficient.

一方、特許文献２に記載の技術は、板厚の変化点(溶接点)については、所定の場所に溶接点が到達した時点で予め計算によって求めたプレナムチャンバ圧力に変更することにより温度制御精度を改善している。しかしながら、特許文献２に記載の技術では、ライン速度の変更時においては、ライン速度変更時点でプレナムチャンバ圧力を変更しなければ目標温度外れが発生してしまうため、プレナムチャンバ圧力の変更タイミングとしては適切ではない。 On the other hand, the technique described in Patent Document 2 has a temperature control accuracy by changing the change point (welding point) of the plate thickness to the plenum chamber pressure obtained by calculation in advance when the welding point reaches a predetermined place. Is improving. However, in the technique described in Patent Document 2, when the line speed is changed, the target temperature is deviated unless the plenum chamber pressure is changed at the time of changing the line speed. Not appropriate.

また、特許文献３に記載の技術は、フィードフォワード的に冷却ブロワ回転数、すなわち、ガスジェットの圧力を変更して操業条件変更の過渡期における温度制御の応答性を改善している。しかしながら、特許文献３に記載の技術では、フィードフォワードで設定するブロワ回転数指令値が金属帯の温度が目標温度に収束した際に安定すべき値となっているため、加減速時間が十分に長い場合、冷却帯を加減速して通過する期間の金属帯に関しては目標温度外れが発生してしまう。また、ブロワ回転数指令値はモデル計算で演算した値を使用しているため、モデル計算の精度がそのまま冷却精度に直結する。例えばライン速度のみが増加する場合、ガスジェットの圧力は必ず上昇方向に操作することになるが、モデル計算を指令値として用いる場合は、圧力実績値よりも必ずしも大きな値となる保証がないため、フィードフォワードの操作としては適切ではない。 Further, the technique described in Patent Document 3 improves the responsiveness of temperature control in the transitional period of changing the operating conditions by changing the cooling blower rotation speed, that is, the pressure of the gas jet in a feed-forward manner. However, in the technique described in Patent Document 3, the blower rotation speed command value set by the feed forward is a value that should be stable when the temperature of the metal band converges to the target temperature, so that the acceleration / deceleration time is sufficient. If it is long, the target temperature deviates from the metal band during the period of accelerating and decelerating the cooling zone. Further, since the blower rotation speed command value uses the value calculated by the model calculation, the accuracy of the model calculation is directly linked to the cooling accuracy. For example, when only the line speed increases, the pressure of the gas jet is always operated in the upward direction, but when the model calculation is used as the command value, there is no guarantee that the pressure will be larger than the actual pressure value. Not suitable as a feed forward operation.

本発明は、上記課題に鑑みてなされたものであって、その目的は、ライン速度変更の過渡期においてガスジェット圧力の変更タイミングを最適化し、冷却帯出側における金属帯の温度変動を低減可能な金属帯の温度制御方法及び温度制御装置を提供することにある。 The present invention has been made in view of the above problems, and an object thereof is to optimize the timing of changing the gas jet pressure in the transitional period of changing the line speed and reduce the temperature fluctuation of the metal band on the cooling band exit side. It is an object of the present invention to provide a temperature control method and a temperature control device for a metal band.

本発明に係る金属帯の温度制御方法は、ガスジェット方式の冷却帯において連続焼鈍後の金属帯を冷却することによって該金属帯の温度を目標温度に制御する金属帯の温度制御方法であって、ライン速度の変更開始時点から加速又は減速して前記冷却帯を通過する前記金属帯の通板方向位置と、ライン速度の変更完了後の速度で前記冷却帯を通過する前記金属帯の通板方向位置と、を少なくとも含む前記金属帯の複数の通板方向位置について、前記冷却帯の通過時間を予測する第１ステップと、前記金属帯の複数の通板方向位置について、前記第１ステップにおいて予測された通過時間を用いて前記冷却帯の出側における前記金属帯の温度を算出する第２ステップと、前記金属帯の通板方向の任意の位置について、ライン速度の変更前の一定速度での前記冷却帯の通過時間を予測する第３ステップと、前記金属帯の通板方向の任意の位置について、前記第３ステップにおいて予測された通過時間を用いて前記冷却帯の出側における前記金属帯の温度を算出する第４ステップと、前記第２ステップにおいて算出された前記金属帯の温度が前記第４ステップにおいて算出された前記金属帯の温度となるように、前記金属帯の複数の通板方向位置において前記冷却帯のガスジェット圧力量を段階的に変更する第５ステップと、を含む。 The method for controlling the temperature of a metal band according to the present invention is a method for controlling the temperature of a metal band in which the temperature of the metal band is controlled to a target temperature by cooling the metal band after continuous annealing in a gas jet type cooling zone. , The position of the metal band passing through the cooling zone after accelerating or decelerating from the start of changing the line speed, and the passing plate of the metal band passing through the cooling zone at the speed after the change of the line speed is completed. In the first step of predicting the passing time of the cooling zone for a plurality of plate-direction positions of the metal band including at least a directional position, and in the first step of a plurality of plate-passing-direction positions of the metal band. The second step of calculating the temperature of the metal band on the exit side of the cooling zone using the predicted transit time and the constant speed before the change of the line speed at an arbitrary position in the through plate direction of the metal band. The metal on the exit side of the cooling zone using the passing time predicted in the third step for the third step of predicting the passing time of the cooling zone and the arbitrary position of the metal band in the through plate direction. A plurality of passages of the metal band so that the temperature of the metal band calculated in the second step is the temperature of the metal band calculated in the fourth step and the fourth step of calculating the temperature of the band. It includes a fifth step of stepwise changing the amount of gas jet pressure in the cooling zone at the plate direction position.

本発明に係る金属帯の温度制御装置は、ガスジェット方式の冷却帯において連続焼鈍後の金属帯を冷却することによって該金属帯の温度を目標温度に制御する金属帯の温度制御装置であって、ライン速度の変更開始時点から加速又は減速して前記冷却帯を通過する前記金属帯の通板方向位置と、ライン速度の変更完了後の速度で前記冷却帯を通過する前記金属帯の通板方向位置と、を少なくとも含む前記金属帯の複数の通板方向位置について、前記冷却帯の通過時間を予測する第１手段と、前記金属帯の複数の通板方向位置について、前記第１手段によって予測された通過時間を用いて前記冷却帯の出側における前記金属帯の温度を算出する第２手段と、前記金属帯の通板方向の任意の位置について、ライン速度の変更前の一定速度での前記冷却帯の通過時間を予測する第３手段と、前記金属帯の通板方向の任意の位置について、前記第３手段によって予測された通過時間を用いて前記冷却帯の出側における前記金属帯の温度を算出する第４手段と、前記第２手段によって算出された前記金属帯の温度が前記第４手段によって算出された前記金属帯の温度となるように、前記金属帯の複数の通板方向位置において前記冷却帯のガスジェット圧力量を段階的に変更する第５手段と、を備える。 The metal band temperature control device according to the present invention is a metal band temperature control device that controls the temperature of the metal band to a target temperature by cooling the metal band after continuous annealing in a gas jet type cooling zone. , The position of the metal band passing through the cooling zone after accelerating or decelerating from the start of changing the line speed, and the passing plate of the metal band passing through the cooling zone at the speed after the change of the line speed is completed. By the first means for predicting the passing time of the cooling zone with respect to the plurality of through plate direction positions of the metal band including at least the directional position, and with respect to the plurality of through plate direction positions of the metal band with respect to the plurality of through plate direction positions of the metal band. A second means of calculating the temperature of the metal band on the exit side of the cooling zone using the predicted transit time, and at an arbitrary position in the through plate direction of the metal band at a constant speed before the change of the line speed. The metal on the exit side of the cooling zone using the third means for predicting the passing time of the cooling zone and the passing time predicted by the third means at an arbitrary position in the plate-passing direction of the metal band. A plurality of passages of the metal band so that the temperature of the metal band calculated by the second means is the temperature of the metal band calculated by the fourth means and the fourth means for calculating the temperature of the band. A fifth means for stepwisely changing the amount of gas jet pressure in the cooling zone at a position in the plate direction is provided.

本発明に係る金属帯の温度制御方法及び温度制御装置によれば、ライン速度変更の過渡期においてガスジェット圧力の変更タイミングを最適化し、冷却帯出側における金属帯の温度変動を低減させることができる。 According to the metal band temperature control method and the temperature control device according to the present invention, it is possible to optimize the gas jet pressure change timing in the transitional period of the line speed change and reduce the temperature fluctuation of the metal band on the cooling band exit side. ..

図１は、本発明の一実施形態である金属帯の温度制御方法が適用される溶融金属めっき鋼板の製造ラインの構成を示す模式図である。FIG. 1 is a schematic view showing the configuration of a production line for a hot-dip metal-plated steel sheet to which the temperature control method for a metal band according to an embodiment of the present invention is applied. 図２は、本発明の一実施形態である金属帯の温度制御処理の流れを示すフローチャートである。FIG. 2 is a flowchart showing a flow of temperature control processing of a metal band according to an embodiment of the present invention. 図３は、実施例における制御点を示す図である。FIG. 3 is a diagram showing control points in the embodiment . 図４は、実施例におけるライン速度の変化の様子を示すグラフである。FIG. 4 is a graph showing a state of change in line speed in the embodiment. 図５は、本発明法及び従来法におけるガスジェット圧力の変更量を示すグラフである。FIG. 5 is a graph showing the amount of change in the gas jet pressure in the method of the present invention and the conventional method . 図６は、本発明法及び従来法における冷却帯出側板温を示すグラフである。 FIG. 6 is a graph showing the cooling band exit side plate temperature in the method of the present invention and the conventional method .

一般に、先行する金属帯と後行する金属帯とを溶接によって順次接続した複数の金属帯を連続的に焼鈍炉で加熱してガスジェット方式の冷却帯で冷却した後、例えば溶融金属めっき処理を施すことにより溶融金属めっき鋼板を製造する過程において、金属帯の搬送速度(ライン速度)が変更されることがある。搬送速度が変更されると、冷却帯での冷却条件変更が追随できずに、冷却帯出側での温度にばらつきが発生する場合があるが、例えば、溶融金属めっきを行う場合、めっき浴温度の制御のために、金属帯の浴侵入温度は重要な制御項目であり、冷却帯出側の温度を制御することが必要になる。本発明に係る金属帯の温度制御方法では、金属帯の板厚、比熱、比重、冷却帯入側温度、ガスジェットの冷却風温度、冷却帯の熱伝達係数、及び冷却帯の通過時間を用いて、冷却帯での金属帯の冷却量、つまり冷却帯出側における金属帯の温度（以下、板温と表記）を算出する。 Generally, a plurality of metal bands in which a preceding metal band and a succeeding metal band are sequentially connected by welding are continuously heated in an annealing furnace and cooled by a gas jet type cooling band, and then, for example, a molten metal plating process is performed. In the process of manufacturing a molten metal plated steel plate, the transport speed (line speed) of the metal band may be changed. When the transport speed is changed, the change in the cooling conditions in the cooling zone cannot keep up and the temperature on the exit side of the cooling zone may vary. For control, the bath intrusion temperature of the metal band is an important control item, and it is necessary to control the temperature on the exit side of the cooling band. In the method for controlling the temperature of the metal band according to the present invention, the plate thickness of the metal band, the specific heat, the specific gravity, the temperature on the cooling zone entry side, the cooling air temperature of the gas jet, the heat transfer coefficient of the cooling zone, and the passing time of the cooling zone are used. Then, the cooling amount of the metal band in the cooling zone, that is, the temperature of the metal band on the exit side of the cooling band (hereinafter referred to as plate temperature) is calculated.

具体的には、本発明に係る金属帯の温度制御方法では、まず、金属帯Ｓの通板方向の任意の位置について、ライン速度変更前の冷却帯出側の板温を板温計算モデル式を用いて算出する。次に、冷却帯入側にある点がライン速度変更開始時から加減速中又は加減速が完了して冷却帯を通過する時間を算出し、算出された通過時間変化によって変動する冷却帯出側の板温を予め板温計算モデル式を用いて算出する。つまり、ガスジェットの圧力変更はないものとして、冷却帯の通過時間だけが変化することによって冷却帯出側の板温がどの程度変化するのかを板温計算モデル式を用いて算出する。次に、加減速が完了した時点で冷却帯入側にある点が加減速完了後の等速度で冷却帯を通過する時間を算出し、算出された通過時間変化によって変動する冷却帯出側の板温を板温計算モデル式を用いて算出する。そして、上記のようにして予め計算したライン速度変更後の板温計算値がライン速度変更前の板温計算値となるように、収束計算によってガスジェットの圧力変更量を算出する。なお、ガスジェット圧力の変更タイミングは少なくとも２点以上設ける。例えば、加減速開始時に冷却帯入側にある点が冷却帯を通過する場合と加減速完了時に冷却帯入側にある点が冷却帯を通過する場合とでは冷却帯を通過する時間が異なるため、冷却帯出側の板温が変化する。このため、この２点において段階的にガスジェット圧力を変更することでより高い温度制御精度を達成できる。 Specifically, in the metal band temperature control method according to the present invention, first, a plate temperature calculation model formula is used to calculate the plate temperature on the cooling band exit side before changing the line speed at an arbitrary position in the plate passing direction of the metal band S. Calculate using. Next, the point on the cooling zone entry side calculates the time during acceleration / deceleration from the start of line speed change or when acceleration / deceleration is completed and passes through the cooling zone, and the time on the cooling zone exit side that fluctuates according to the calculated passage time change. The plate temperature is calculated in advance using the plate temperature calculation model formula. That is, assuming that the pressure of the gas jet does not change, how much the plate temperature on the exit side of the cooling zone changes due to the change only in the passing time of the cooling zone is calculated by using the plate temperature calculation model formula. Next, the time at which the point on the cooling zone entry side when acceleration / deceleration is completed passes through the cooling zone at the same speed after acceleration / deceleration is completed is calculated, and the plate on the cooling zone exit side that fluctuates according to the calculated passage time change. The temperature is calculated using the plate temperature calculation model formula. Then, the pressure change amount of the gas jet is calculated by the convergence calculation so that the plate temperature calculation value after the line speed change calculated in advance as described above becomes the plate temperature calculation value before the line speed change. At least two points should be set for changing the gas jet pressure. For example, the time to pass through the cooling zone differs depending on whether the point on the cooling zone entry side at the start of acceleration / deceleration passes through the cooling zone or the point on the cooling zone entry side at the completion of acceleration / deceleration passes through the cooling zone. , The plate temperature on the exit side of the cooling zone changes. Therefore, higher temperature control accuracy can be achieved by changing the gas jet pressure stepwise at these two points.

以下、上記の概念に基づいて想倒された、本発明の一実施形態である金属帯の温度制御方法について説明する。 Hereinafter, a method for controlling the temperature of a metal band, which is an embodiment of the present invention, which was conceived based on the above concept, will be described.

まず、図１を参照して、本発明の一実施形態である金属帯の温度制御方法が適用される溶融金属めっき鋼板の製造ラインの構成について説明する。 First, with reference to FIG. 1, the configuration of a production line for a hot-dip metal-plated steel sheet to which the temperature control method for a metal band according to an embodiment of the present invention is applied will be described.

図１は、本発明の一実施形態である金属帯の温度制御方法が適用される溶融金属めっき鋼板の製造ラインの構成を示す模式図である。図１に示すように、本発明の一実施形態である金属帯の温度制御方法が適用される溶融金属めっき鋼板の製造ライン１では、金属帯Ｓは、加熱帯２において所定温度まで加熱された後、冷却帯３において冷却されて温度調整される。冷却帯３内のガスジェットノズル４からは金属帯Ｓに冷却ガスが吹き付けられ（ガスジェット冷却）、温度調整された金属帯Ｓは、スナウト５内を通ってめっき浴６に侵入する。冷却帯３の出側には板温計７が配置されており、冷却帯３の出側における板温が測定される。板温計７によって測定された板温を示す電気信号は制御装置８へ入力される。制御装置８は、上位計算機９から入力される板温目標値と板温計７により測定された板温測定値との差がゼロとなるようにダンパ１０の開度を調整する。具体的には、冷却帯３内の雰囲気ガスを熱交換器１１により冷却し、ファン１２を用いて金属帯Ｓに高圧の雰囲気ガスを吹き付けることにより、金属帯Ｓを急冷する。 FIG. 1 is a schematic view showing the configuration of a production line for a hot-dip metal-plated steel sheet to which the temperature control method for a metal band according to an embodiment of the present invention is applied. As shown in FIG. 1, in the molten metal-plated steel sheet production line 1 to which the method for controlling the temperature of the metal band according to the embodiment of the present invention is applied, the metal band S is heated to a predetermined temperature in the heating band 2. After that, it is cooled in the cooling zone 3 and the temperature is adjusted. Cooling gas is blown onto the metal band S from the gas jet nozzle 4 in the cooling zone 3 (gas jet cooling), and the temperature-controlled metal band S penetrates into the plating bath 6 through the snout 5. A plate temperature gauge 7 is arranged on the outlet side of the cooling zone 3, and the plate temperature on the outlet side of the cooling zone 3 is measured. An electric signal indicating the plate temperature measured by the plate temperature gauge 7 is input to the control device 8. The control device 8 adjusts the opening degree of the damper 10 so that the difference between the plate temperature target value input from the host computer 9 and the plate temperature measured value measured by the plate temperature gauge 7 becomes zero. Specifically, the atmospheric gas in the cooling zone 3 is cooled by the heat exchanger 11, and the metal zone S is rapidly cooled by blowing the high-pressure atmospheric gas onto the metal band S using the fan 12.

なお、冷却帯３でのガスジェット冷却による板温は、以下の数式(１)に示す板温計算モデル式を用いて計算することができる。数式（１）中、Ｔは冷却帯出側板温［℃］、Ｔ_ｇは冷却ガスの温度［℃］、Ｔ_０は冷却帯入側板温［℃］、Ａは定数［－］、Ｐはガスジェット圧力［Ｐａ］、ｘは係数［－］、ｃは金属帯Ｓの比熱［ｃａｌ／（ｋｇ・Ｋ）]、ρは金属帯の比重［ｋｇ／ｍ^３]、Ｄは金属帯の厚さ［ｍ］、ｔは冷却帯の通過時間［ｓｅｃ］を示している。 The plate temperature due to gas jet cooling in the cooling zone 3 can be calculated using the plate temperature calculation model formula shown in the following formula (1). In formula (1), T is the cooling zone exit side plate temperature [° C], T _g is the cooling gas temperature [° C], T ₀ is the cooling zone entry side plate temperature [° C], A is a constant [-], and P is the gas jet. Pressure [Pa], x is a coefficient [-], c is the specific heat of the metal band S [cal / (kg · K)], ρ is the specific gravity of the metal band [kg / m ³ ], and D is the thickness of the metal band [ m] and t indicate the passage time [sec] of the cooling zone.

次に、図２を参照して、本発明の一実施形態である金属帯の温度制御処理について説明する。図２は、本発明の一実施形態である金属帯の温度制御処理の流れを示すフローチャートである。図２に示すフローチャートは、制御装置８にライン速度変更指令が入力されたタイミングで開始となり、温度制御処理はステップＳ１の処理に進む。 Next, with reference to FIG. 2 , a temperature control process for a metal band, which is an embodiment of the present invention, will be described. FIG. 2 is a flowchart showing a flow of temperature control processing of a metal band according to an embodiment of the present invention . The flowchart shown in FIG. 2 starts at the timing when the line speed change command is input to the control device 8, and the temperature control process proceeds to the process of step S1.

図２に示すように、本発明の一実施形態である金属帯の温度制御処理では、まず、制御装置８が、金属帯Ｓの複数の通板方向位置について冷却帯３を通過する時間を演算する（ステップＳ１）。次に、制御装置８は、ステップＳ１の処理において算出された通過時間を用いて、金属帯の複数の通板方向位置について冷却帯を通過するまでの板温の変化量を予測し（ステップＳ２）、ライン速度変更後の板温がライン速度変更前の板温となるようなガスジェット圧力を収束計算する（ステップＳ３）。そして、制御装置８は、収束計算されたガスジェット圧力となるようにガスジェット圧力の変更量を算出し（ステップＳ４）、算出されたガスジェット圧力の変更量に基づいて金属帯の複数の通板方向位置においてガスジェット圧力を段階的に変更するようにダンパ１０の開度を制御する（ステップＳ５，Ｓ６）。 As shown in FIG. 2, in the temperature control process of the metal band according to the embodiment of the present invention, first, the control device 8 calculates the time for passing through the cooling band 3 with respect to the positions of the metal band S in the direction of the plurality of plates. (Step S1). Next, the control device 8 predicts the amount of change in the plate temperature until passing through the cooling zone for a plurality of plate-passing direction positions of the metal band using the passing time calculated in the process of step S1 (step S2). ), The gas jet pressure is calculated so that the plate temperature after the line speed change becomes the plate temperature before the line speed change (step S3). Then, the control device 8 calculates the change amount of the gas jet pressure so as to be the convergent calculated gas jet pressure (step S4), and a plurality of passages of the metal band based on the calculated change amount of the gas jet pressure. The opening degree of the damper 10 is controlled so as to change the gas jet pressure stepwise at the plate direction position (steps S5 and S6).

より具体的には、本発明の一実施形態である温度制御処理では、まず、制御装置８は、以下に示す数式（２）を用いてライン速度の加速開始から加速完了までの時間ｔ_１を算出する。ここで、数式（２）において、Ｖ_０は加速前の金属帯Ｓの速度［ｍ／ｍｉｎ］、Ｖは加速完了後の金属帯Ｓの速度［ｍ／ｍｉｎ］、αは加速率[ｍ／ｓ^２]を示す。次に、制御装置８は、以下に示す数式（３）を用いて加速完了までに金属帯Ｓが進む距離ｘ_１［ｍ］を算出する。次に、制御装置８は、冷却帯３の設備長Ｌ［ｍ］と加速完了までに金属帯Ｓが進む距離ｘ_１［ｍ］とを比較する。 More specifically, in the temperature control process according to the embodiment of the present invention, first, the control device 8 uses the following mathematical formula (2) to set the time t ₁ from the start of acceleration of the line speed to the completion of acceleration. calculate. Here, in the mathematical formula (2), V ₀ is the velocity [m / min] of the metal band S before acceleration, V is the velocity [m / min] of the metal band S after the acceleration is completed, and α is the acceleration rate [m / min]. s ² ] is shown. Next, the control device 8 calculates the distance x ₁ [m] that the metal band S travels until the acceleration is completed by using the mathematical formula (3) shown below. Next, the control device 8 compares the equipment length L [m] of the cooling zone 3 with the distance x ₁ [m] that the metal band S travels until the acceleration is completed.

まず、比較の結果、金属帯Ｓが進む距離ｘ_１［ｍ］の方が設備長Ｌ［ｍ］よりも長い場合を考える。この場合、加速開始時に冷却帯３内入側にある点(制御点１)は冷却帯３内を等加速度で通過する。また、加速完了した時点で冷却帯３入側にある点(制御点２)は冷却帯３内を等速度で通過する。この制御点１と制御点２とでは、冷却帯３を通過する時間が異なるため、冷却帯３出側での板温が異なる。そこでまず、制御装置８は、制御点１が冷却帯３を通過する時間ｔ_４を以下に示す数式（４）を用いて算出する。次に、制御装置８は、制御点２が冷却帯３を通過する時間ｔ_５を以下に示す数式（５）を用いて算出する。 First, as a result of comparison, consider the case where the distance x ₁ [m] traveled by the metal band S is longer than the equipment length L [m]. In this case, the point (control point 1) on the inside / inside side of the cooling zone 3 at the start of acceleration passes through the cooling zone 3 at a constant acceleration. Further, the point (control point 2) on the cooling zone 3 entry side when the acceleration is completed passes through the cooling zone 3 at a constant speed. Since the time for passing through the cooling zone 3 is different between the control point 1 and the control point 2, the plate temperature on the exit side of the cooling zone 3 is different. Therefore, first, the control device 8 calculates the time t ₄ at which the control point 1 passes through the cooling zone 3 by using the mathematical formula (4) shown below. Next, the control device 8 calculates the time t ₅ at which the control point 2 passes through the cooling zone 3 by using the mathematical formula (5) shown below.

次に、制御装置８は、制御点１が冷却帯を時間ｔ_４で通過することで変化する板温を数式（１）に示す板温計算モデル式を用いて計算し、算出された板温が速度変更前の板温となるようなガスジェット圧力Ｐ１［Ｐａ］を収束計算(ニュートン法)のフローに従って計算する。 Next, the control device 8 calculates the plate temperature that changes as the control point ₁ passes through the cooling zone at time t4 using the plate temperature calculation model formula shown in the equation (1), and the calculated plate temperature is calculated. The gas jet pressure P1 [Pa] , which is the plate temperature before the speed change, is calculated according to the flow of the convergence calculation (Newton's method) .

次に、制御装置８は、制御点２が冷却帯を時間ｔ_５で通過することで変化する板温を数式（１）に示す板温計算モデル式を用いて計算し、算出された板温が速度変更前の板温となるような圧力Ｐ２［Ｐａ］を収束計算のフローに従って計算する。そして、求めた圧力Ｐ１，Ｐ２への変更タイミングは、圧力Ｐ１に関しては、加速開始と同時に圧力を圧力Ｐ１に変更し、圧力Ｐ２に関しては制御点２が冷却帯入側に到達した時点で圧力Ｐ２に変更する。制御点２が冷却帯入側に到達する時間は、上記数式（２）で求めた時刻となる。 Next, the control device 8 calculates the plate temperature that changes as the control point ₂ passes through the cooling zone at time t5 using the plate temperature calculation model formula shown in the equation (1), and the calculated plate temperature is calculated. The pressure P2 [Pa] such that becomes the plate temperature before the speed change is calculated according to the flow of the convergence calculation. Then, the obtained change timing to the pressures P1 and P2 is such that the pressure is changed to the pressure P1 at the same time as the acceleration starts for the pressure P1, and the pressure P2 is changed when the control point 2 reaches the cooling zone entry side for the pressure P2. Change to. The time when the control point 2 reaches the cooling zone entry side is the time calculated by the above mathematical formula (2).

一方、金属帯Ｓが進む距離ｘ_１［ｍ］の方が設備長Ｌ［ｍ］よりも短い場合には、加速開始時に冷却帯入側にある点(制御点１)は、冷却帯内で加速完了し、等速度で冷却帯内を通過する。また、加速完了した時点で冷却帯入側にある点(制御点２)は、冷却帯内を等速度で通過する。この制御点１と制御点２とでは、冷却帯を通過する時間が異なるため、冷却帯出側での板温が異なる。そこで、まず、制御装置８は、制御点１が冷却帯を通過する時間ｔ_６を以下に示す数式（６）を用いて算出する。次に、制御装置８は、制御点２が冷却帯３を通過する時間ｔ_５を上記数式（５）を用いて算出する。 On the other hand, when the distance x ₁ [m] traveled by the metal band S is shorter than the equipment length L [m], the point (control point 1) on the cooling zone entry side at the start of acceleration is within the cooling zone. Acceleration is completed and it passes through the cooling zone at a constant speed. Further, the point (control point 2) on the cooling zone entry side when the acceleration is completed passes through the cooling zone at a constant speed. Since the time for passing through the cooling zone is different between the control point 1 and the control point 2, the plate temperature on the cooling zone exit side is different. Therefore, first, the control device 8 calculates the time t ₆ at which the control point 1 passes through the cooling zone by using the mathematical formula (6) shown below. Next, the control device 8 calculates the time t ₅ at which the control point 2 passes through the cooling zone 3 by using the above equation (5).

次に、制御装置８は、制御点１が冷却帯を時間ｔ_６で通過することで変化する板温を数式（１）に示す板温計算モデル式を用いて計算し、算出された板温が速度変更前の板温となるような圧力Ｐ３を収束計算のフローに従って計算する。次に、制御装置８は、制御点２が冷却帯を時間ｔ_５で通過することで変化する板温を数式（１）に示す板温計算モデル式を用いて計算し、算出された板温が速度変更前の板温となるような圧力Ｐ４を収束計算のフローに従って計算する。求めた圧力Ｐ３，Ｐ４への変更タイミングは、圧力Ｐ３に関しては、加速開始と同時に圧力をＰ３に変更し、圧力Ｐ４に関しては制御点２が冷却帯入側に到達した時点で圧力Ｐ４に変更する。制御点２が冷却帯入側に到達する時間は、上記数式（２）により求めた時刻となる。なお、上記手法は、加速の場合に関して記述しているが、減速の場合も計算式を変更するだけで同様の考え方を適用できる。これにより、金属帯の温度制御処理は終了する。 Next, the control device 8 calculates the plate temperature that changes as the control point ₁ passes through the cooling zone at time t6 using the plate temperature calculation model formula shown in the equation (1), and the calculated plate temperature is calculated. The pressure P3 such that becomes the plate temperature before the speed change is calculated according to the flow of the convergence calculation. Next, the control device 8 calculates the plate temperature that changes as the control point ₂ passes through the cooling zone at time t5 using the plate temperature calculation model formula shown in the equation (1), and the calculated plate temperature is calculated. The pressure P4 is calculated according to the flow of the convergence calculation so that the plate temperature becomes the plate temperature before the speed change. As for the obtained change timing to the pressures P3 and P4, the pressure is changed to P3 at the same time as the acceleration starts for the pressure P3, and the pressure P4 is changed to the pressure P4 when the control point 2 reaches the cooling zone entry side for the pressure P4. .. The time for the control point 2 to reach the cooling zone entry side is the time calculated by the above mathematical formula (2). Although the above method is described for the case of acceleration, the same idea can be applied to the case of deceleration only by changing the calculation formula. This completes the temperature control process for the metal band.

以上の説明から明らかなように、本発明の一実施形態である金属帯の温度制御処理では、ライン速度変更時の過渡期において、冷却帯出側の金属帯Ｓの板温を冷却モデル計算で予測し、予測された板温がライン速度変更前の板温となるように、ライン速度変更時に加速開始時点から加速して冷却帯を通過する点と、ライン速度変更完了後の速度で冷却帯を通過する点において段階的にガスジェットの圧力をフィードフォワード的に変更するようにしたので、ライン速度変更時の過渡期における板温制御をより高精度に行うことができる。また、この結果、目標温度管理範囲外れとなる部分を減少させて表面欠陥不良の発生を抑制できる。また、浴中ドロスの発生自体を減少させることができるので、プレス加工時、ドロス付着に起因する不良発生率の低い溶融金属めっき鋼板を製造できる。なお、段階的にガスジェットの圧力を変更するタイミングは、任意の時間(計算値)で行うことが望ましいが、トラッキングを利用してもよい。さらに、加速完了までに段階的に圧力変更を行う回数は、限定されるものではなく設備の応答性を考慮して任意の回数で段階的に変更することが望ましい。 As is clear from the above description, in the temperature control process of the metal band according to the embodiment of the present invention, the plate temperature of the metal band S on the cooling band exit side is predicted by the cooling model calculation in the transitional period when the line speed is changed. Then, so that the predicted plate temperature becomes the plate temperature before the line speed change, the cooling zone is set at the point where it accelerates from the start of acceleration and passes through the cooling zone when the line speed is changed, and at the speed after the line speed change is completed. Since the pressure of the gas jet is changed stepwise in a feed-forward manner at the passing point, the plate temperature control in the transitional period when the line speed is changed can be performed with higher accuracy. Further, as a result, it is possible to reduce the portion outside the target temperature control range and suppress the occurrence of surface defect defects. Further, since the generation of dross in the bath itself can be reduced, it is possible to manufacture a molten metal plated steel sheet having a low defect occurrence rate due to dross adhesion during press working. The timing of changing the pressure of the gas jet step by step is preferably performed at an arbitrary time (calculated value), but tracking may be used. Further, the number of times the pressure is changed stepwise until the acceleration is completed is not limited, and it is desirable to change the pressure stepwise at an arbitrary number in consideration of the responsiveness of the equipment.

本実施例では、本発明に係る金属帯の温度制御方法の有効性をシミュレーションによって検証した。図３は本シミュレーションにおける制御点を示す図である。本シミュレーションでは、冷却帯が３ゾーンある場合を想定している。今回、加速開始時に３ゾーン入側にある点を制御点Ａ（図３（ａ）参照）、加速開始時に２ゾーン入側にある点を制御点Ｂ（図３（ｂ）参照）、加速開始時に１ゾーン入側にある点を制御点Ｃとし（図３（ｃ）参照）、加速完了時点で冷却帯入側に到達する点を制御点Ｄ（図３（ｄ）参照）としている。ガスジェット圧力の変更タイミングとしては各制御点が冷却帯の各ゾーン入側に到達した時点で３ゾーンのガスジェット圧力（３ゾーン圧力）を変更する（図３（ｅ）参照）。 In this embodiment, the effectiveness of the temperature control method for the metal band according to the present invention was verified by simulation. FIG. 3 is a diagram showing control points in this simulation. In this simulation, it is assumed that there are three cooling zones. This time, the point on the 3 zone entry side at the start of acceleration is the control point A (see FIG. 3 (a)), the point on the 2 zone entry side at the start of acceleration is the control point B (see FIG. 3 (b)), and the acceleration start. Occasionally, the point on the entry side of one zone is defined as the control point C (see FIG. 3C ), and the point reaching the cooling zone entry side at the completion of acceleration is defined as the control point D (see FIG. 3D ). As for the change timing of the gas jet pressure, the gas jet pressure in the three zones (three zone pressure) is changed when each control point reaches the entry side of each zone in the cooling zone (see FIG. 3 (e)).

図４は、本シミュレーションにおけるライン速度の変化の様子を示すグラフである。図５は、本発明法及び従来法におけるガスジェット圧力の変更量を示すグラフである。図６は、本発明法及び従来法における冷却帯出側板温を示すグラフである。なお、本シミュレーションでの板温制御はフィードフォワード制御のみを使用している。図４に示すように、ライン速度は、本発明法及び従来法共に１２０［ｍｐｍ］から１３０［ｍｐｍ］に変更されている。図５に示すように、従来法ではライン速度変更完了後の定常速度で板温変化がなくなるように、加速開始時に３ゾーン圧力を変更しているのに対して、本発明法では、ライン速度の加速中と加速完了後との冷却帯通過時間予測に基づいて、金属帯の搬送方向の複数の位置(制御点)において３ゾーン圧力を段階的に変更している。 FIG. 4 is a graph showing how the line speed changes in this simulation. FIG. 5 is a graph showing the amount of change in the gas jet pressure in the method of the present invention and the conventional method. FIG. 6 is a graph showing the cooling band exit side plate temperature in the method of the present invention and the conventional method. The plate temperature control in this simulation uses only feedforward control. As shown in FIG. 4 , the line speed is changed from 120 [mpm] to 130 [mpm] in both the present invention method and the conventional method. As shown in FIG. 5 , in the conventional method, the three-zone pressure is changed at the start of acceleration so that the plate temperature does not change at the steady speed after the line speed change is completed, whereas in the present invention method, the line speed is changed. The three-zone pressure is changed stepwise at a plurality of positions (control points) in the transport direction of the metal band based on the prediction of the cooling zone transit time during and after the acceleration.

図６に示すように、従来法での冷却帯出側板温は、加速開始と同時に３ゾーン圧力を最終目標値へ一気に変更するため、加速開始時点では過冷却となっている。これに対して、本発明法では、３ゾーン圧力を段階的に上げていくため従来法に比べて精度よく冷却帯出側板温を制御できている。また、本発明法ではモデル計算上でのガスジェット圧力変更量を操業中の圧力実績値に補正する形で加えるため、モデル計算値をそのまま指令値として用いるよりもガスジェット圧力外れ(目標板温外れ)のリスクが少ない。これは、加速でガスジェット圧力を上げる方向、減速でガスジェット圧力を下げる方向と補正方向が常に決まっているためである。このように、本発明法によれば、従来法よりもライン速度変更中における冷却帯出側の板温変動を低減できることが確認された。 As shown in FIG. 6 , the cooling zone exit side plate temperature in the conventional method is supercooled at the start of acceleration because the pressure in the three zones is changed to the final target value at once at the same time as the start of acceleration. On the other hand, in the method of the present invention, since the pressure in the three zones is gradually increased, the cooling zone exit side plate temperature can be controlled more accurately than in the conventional method. Further, in the method of the present invention, since the gas jet pressure change amount in the model calculation is added in the form of correcting the actual pressure value during operation, the gas jet pressure deviates (target plate temperature) rather than using the model calculated value as it is as a command value. There is little risk of disengagement. This is because the direction in which the gas jet pressure is increased by acceleration, the direction in which the gas jet pressure is decreased by deceleration, and the correction direction are always determined. As described above, it was confirmed that according to the method of the present invention, the fluctuation of the plate temperature on the cooling band exit side during the change of the line speed can be reduced as compared with the conventional method.

以上、本発明者らによってなされた発明を適用した実施形態について説明したが、本実施形態による本発明の開示の一部をなす記述及び図面により本発明は限定されることはない。すなわち、本実施形態に基づいて当業者等によりなされる他の実施の形態、実施例、及び運用技術等は全て本発明の範疇に含まれる。 Although the embodiment to which the invention made by the present inventors has been applied has been described above, the present invention is not limited by the description and the drawings which form a part of the disclosure of the present invention according to the present embodiment. That is, other embodiments, examples, operational techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

１溶融金属めっき鋼板の製造ライン
２加熱帯
３冷却帯
４ガスジェットノズル
５スナウト
６めっき浴
７板温計
８制御装置
９上位計算機
１０ダンパ
１１熱交換器
１２ファン
Ｓ金属帯 1 Production line of molten metal plated steel sheet 2 Heating band 3 Cooling band 4 Gas jet nozzle 5 Snout 6 Plating bath 7 Plate thermometer 8 Control device 9 Upper computer 10 Damper 11 Heat exchanger 12 Fan S Metal band

Claims

It is a temperature control method for a metal band that controls the temperature of the metal band to a target temperature by cooling the metal band after continuous annealing in a gas jet type cooling zone.
In response to the input of the line speed change command, the first position, which is the position in the cooling zone in the plate direction of the metal band at the start of the line speed change, and the cooling zone at the completion of the line speed change. With respect to the second position, which is the position in the plate-passing direction of the metal band on the entry side, the first step of predicting the passing time of the cooling zone, and
A second step of calculating the temperature of the metal band on the exit side of the cooling zone using the transit time and gas jet pressure predicted in the first step for the first position and the second position.
For the first position and the second position, a third step of predicting the passing time of the cooling zone at a constant speed before the change of the line speed, and
A fourth step of calculating the temperature of the metal band on the exit side of the cooling zone using the transit time and gas jet pressure predicted in the third step for the first position and the second position.
For the first position, the gas jet pressure amount of the cooling zone where the temperature of the metal band calculated in the second step becomes the temperature of the metal band calculated in the fourth step is calculated as the first pressure amount. Then, for the second position, the gas jet pressure amount of the cooling zone in which the temperature of the metal band calculated in the second step becomes the temperature of the metal band calculated in the fourth step is the second pressure amount. The gas jet pressure in the cooling zone is changed to the first pressure at the start of changing the line speed, and the gas jet pressure in the cooling zone is reached when the second position reaches the entry side of the cooling zone. The fifth step of changing the amount to the second pressure amount,
A method for controlling the temperature of a metal band, which comprises.

It is a temperature control device for a metal band that controls the temperature of the metal band to a target temperature by cooling the metal band after continuous annealing in a gas jet type cooling zone.
In response to the input of the line speed change command, the first position, which is the position in the cooling zone in the plate direction of the metal band at the start of the line speed change, and the cooling zone at the completion of the line speed change. With respect to the second position, which is the position in the plate-passing direction of the metal band on the entry side, the first means for predicting the passing time of the cooling zone, and
A second means for calculating the temperature of the metal band on the exit side of the cooling zone using the transit time and gas jet pressure predicted by the first means for the first position and the second position.
With respect to the first position and the second position, a third means for predicting the passing time of the cooling zone at a constant speed before the change of the line speed, and
A fourth means for calculating the temperature of the metal band on the exit side of the cooling zone using the transit time and gas jet pressure predicted by the third means for the first position and the second position.
For the first position, the gas jet pressure amount of the cooling zone in which the temperature of the metal band calculated by the second means becomes the temperature of the metal band calculated by the fourth means is calculated as the first pressure amount. Then, for the second position, the gas jet pressure amount of the cooling zone in which the temperature of the metal band calculated by the second means becomes the temperature of the metal band calculated by the fourth means is the second pressure amount. The gas jet pressure in the cooling zone is changed to the first pressure at the start of changing the line speed, and the gas jet pressure in the cooling zone is reached when the second position reaches the entry side of the cooling zone. Fifth means to change the amount to the second pressure amount,
A metal band temperature control device comprising.