JP6597338B2 - Cooling method and steel plate manufacturing method - Google Patents
Cooling method and steel plate manufacturing method Download PDFInfo
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Description
本発明は、鋼板を冷却する冷却方法及び鋼板の製造方法に関する。 The present invention relates to a cooling method for cooling a steel plate and a method for manufacturing a steel plate.
熱間で圧延された鋼板は、冷却工程において冷却される（特許文献１〜特許文献６参照）。この冷却工程では、遷移沸騰領域での不安定な冷却により生ずる鋼板の板内温度偏差によって、冷却後の鋼板の形状、材質が悪化することに苦慮してきた。 The steel sheet rolled hot is cooled in a cooling process (refer patent document 1-patent document 6). In this cooling process, it has been difficult to deteriorate the shape and material of the steel plate after cooling due to temperature deviation in the steel plate caused by unstable cooling in the transition boiling region.
この際、鋼板の冷却に使用する水温が沸騰現象（特に極小熱流束点）に影響を及ぼすことは知られているが、冷却に使用する冷却水を瞬時に温度調整することは困難である。このため、例えば特許文献１には、冷却に使用する水温を制御して遷移沸騰領域を避けるのではなく、水量密度を制御する方法について示されている。 At this time, it is known that the water temperature used for cooling the steel sheet affects the boiling phenomenon (particularly the minimum heat flux point), but it is difficult to instantaneously adjust the temperature of the cooling water used for cooling. For this reason, for example, Patent Document 1 discloses a method of controlling the water density rather than controlling the water temperature used for cooling to avoid the transition boiling region.
また、特許文献２には、冷却に使用する水温を調整することで、膜沸騰の持続時間を長くしてクエンチ点を下げ、遷移沸騰領域を避ける方法について示されているが、予め定められた鋼板のみを対象とする。このため、水温の積極的な制御により膜沸騰と核沸騰とを使い分けるという考え方はなかった。 Patent Document 2 discloses a method of adjusting the water temperature used for cooling to increase the film boiling duration to lower the quench point and avoid the transition boiling region. Only for steel plates. For this reason, there was no idea of properly using film boiling and nucleate boiling by actively controlling the water temperature.
このように、これらの冷却方法にあっては、冷却に使用する水温を積極的に制御することで、連続して冷却される複数の鋼板に対して、例えば遷移沸騰領域での冷却を回避することは実施されていなかった。 As described above, in these cooling methods, by actively controlling the water temperature used for cooling, for example, cooling in a transition boiling region is avoided for a plurality of continuously cooled steel plates. That was not done.
本発明は、鋼板の形状や材質悪化を抑制する冷却方法を提供することを目的とする。 An object of this invention is to provide the cooling method which suppresses the shape and material deterioration of a steel plate.
本発明の第一態様によれば、熱間圧延された複数の鋼板を所定の処理単位ごとに冷却する際の冷却水温度を制御する冷却方法であって、前記処理単位のうちの個別の鋼板に用いる最適冷却水温度を過去の冷却実績より定めた第１評価指標に基づいて求め、前記処理単位で冷却する複数の鋼板を、前記第１評価指標に基づいて求めた前記最適冷却水温度毎に分類し、分類された鋼板毎に複数の目標温度候補で冷却した場合の優劣を数値化した第２評価指標を求め、前記目標温度候補毎に前記第２評価指標を合計した合計値を求め、前記目標温度候補毎に合計された各合計値に基づいて各目標温度候補の中から前記処理単位を通じて用いる冷却水の目標温度を求め、前記処理単位で冷却する際の冷却水温度が前記目標温度となるように制御する冷却方法が提供される。 According to the first aspect of the present invention, there is provided a cooling method for controlling a cooling water temperature when cooling a plurality of hot-rolled steel plates for each predetermined processing unit, and each of the processing units is an individual steel plate. For each of the optimum cooling water temperatures obtained based on the first evaluation index, a plurality of steel plates to be cooled in the processing unit are obtained based on the first evaluation index. The second evaluation index is obtained by quantifying the superiority or inferiority when cooling with a plurality of target temperature candidates for each classified steel sheet, and the total value obtained by summing the second evaluation indices for each target temperature candidate is obtained. Then, a target temperature of cooling water to be used through the processing unit is obtained from each target temperature candidate based on each total value totaled for each target temperature candidate, and the cooling water temperature when cooling in the processing unit is the target Cold controlled to be at temperature A method is provided.
本発明の第二態様によれば、第一態様において、前記第１評価指標より定まる冷却水温度を用いて第１温度設定テーブルを形成し該第１温度設定テーブルから前記最適冷却水温度を求めるとともに、前記第２評価指標を用いて第２温度設定テーブルを形成し該第２温度設定テーブルから前記目標温度を求める。 According to a second aspect of the present invention, in the first aspect, a first temperature setting table is formed using a cooling water temperature determined from the first evaluation index, and the optimum cooling water temperature is obtained from the first temperature setting table. At the same time, a second temperature setting table is formed using the second evaluation index, and the target temperature is obtained from the second temperature setting table.
本発明の第三態様によれば、第一態様又は第二態様において、前記第１評価指標が、再矯正率、最大波高さ、最大歪量、材質合格率、又は再矯正時間のいずれか一つである。 According to a third aspect of the present invention, in the first aspect or the second aspect, the first evaluation index is any one of a re-correction rate, a maximum wave height, a maximum strain amount, a material pass rate, or a re-correction time. One.
本発明の第四態様によれば、第一態様から第三態様のいずれか一つの態様において、前記第２評価指標が、前記処理単位で冷却される鋼板全体の再矯正率、再矯正本数、最大波高さの平均値、最大歪量の平均値、材質合格率、材質合格本数、又は再矯正時間の平均値のいずれか一つである。 According to the fourth aspect of the present invention, in any one aspect of the first aspect to the third aspect, the second evaluation index is the recorrection rate of the entire steel sheet cooled in the processing unit, the number of recorrections, The average value of the maximum wave height, the average value of the maximum strain amount, the material pass rate, the number of material passes, or the average value of the re-correction time.
本発明の第五態様によれば、第一態様から第四態様のいずれか一つの態様において、前記処理単位を、冷却する鋼板の数、一定の処理時間、又は任意の処理時間で定め、当該処理単位毎に前記目標温度を求めて更新する。 According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the processing unit is determined by the number of steel plates to be cooled, a constant processing time, or an arbitrary processing time, The target temperature is obtained and updated for each processing unit.
本発明の第六態様によれば、鋼片を加熱する加熱工程と、該加熱工程で加熱された鋼片を圧延して鋼板とする圧延工程と、該圧延工程で圧延された鋼板を、第一態様から第五態様のいずれか一つの態様の冷却方法で冷却する冷却工程と、を備える鋼板の製造方法が提供される。 According to the sixth aspect of the present invention, a heating step for heating a steel slab, a rolling step for rolling the steel slab heated in the heating step into a steel plate, and a steel plate rolled in the rolling step, There is provided a method for producing a steel sheet comprising: a cooling step of cooling by the cooling method according to any one of the first to fifth aspects.
本発明により、複数種の鋼板を所定の処理単位で冷却する場合に鋼板の形状や材質悪化を抑制する技術が提供される。 According to the present invention, there is provided a technique for suppressing deterioration of the shape and material of a steel plate when a plurality of types of steel plates are cooled in predetermined processing units.
以下、本発明の一実施形態を図面に従って説明する。図１は、本実施形態に係る冷却方法を実施する設備を示す平面図であり、上流側にはデパイラー１０で搬送された鋼板１２を加熱する加熱工程を実行する為の加熱装置１４が設けられている。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing equipment for performing the cooling method according to the present embodiment, and a heating device 14 for performing a heating process for heating the steel plate 12 conveyed by the depiler 10 is provided on the upstream side. ing.
加熱装置１４の下流には、スケール除去装置（ＨＳＢ）１６が設けられており、スケール除去装置１６の下流には、圧延工程を実行する圧延装置１８が設けられている。圧延装置１８には、粗圧延機（ＲＭ）２０と、仕上げ圧延機（ＦＭ）２２と、ホットレベラー（ＨＬ）２４が上流側よりこの順に設けられている。これにより、スケール除去装置１６から送られた鋼板１２を、搬送路２６に沿って搬送することで、粗圧延機２０及び仕上げ圧延機２２で熱間圧延した後、ホットレベラー２４で矯正できるように構成されている。 A scale removing device (HSB) 16 is provided downstream of the heating device 14, and a rolling device 18 that performs a rolling process is provided downstream of the scale removing device 16. The rolling device 18 is provided with a rough rolling mill (RM) 20, a finish rolling mill (FM) 22, and a hot leveler (HL) 24 in this order from the upstream side. Thereby, the steel plate 12 sent from the scale removing device 16 is conveyed along the conveying path 26 so that it can be corrected by the hot leveler 24 after hot rolling by the roughing mill 20 and the finish rolling mill 22. It is configured.
ホットレベラー２４の下流には、冷却工程を実行する加速冷却装置（ＡＣＣ）３０が設けられており、熱間圧延された鋼板１２を加速冷却装置３０で冷却できるよう構成されている。加速冷却装置３０は、鋼板１２に冷却水を噴射して冷却する装置であり、この加速冷却装置３０には、冷却水供給路３２を介して貯留槽３４からの冷却水が供給されるように構成されている。また、加速冷却装置３０は、鋼板１２の冷却に使用した冷却水を、冷却水帰還路３６を介して貯留槽３４に戻せるよう構成されており、冷却水を加速冷却装置３０と貯留槽３４との間で循環できるように構成されている。 An accelerated cooling device (ACC) 30 that performs a cooling process is provided downstream of the hot leveler 24, and the hot-rolled steel plate 12 can be cooled by the accelerated cooling device 30. The accelerated cooling device 30 is a device that cools the steel plate 12 by injecting cooling water. The accelerated cooling device 30 is supplied with cooling water from the storage tank 34 via the cooling water supply path 32. It is configured. The accelerated cooling device 30 is configured so that the cooling water used for cooling the steel plate 12 can be returned to the storage tank 34 via the cooling water return path 36, and the cooling water is supplied to the accelerated cooling apparatus 30 and the storage tank 34. It is configured to be able to circulate between.
冷却水供給路３２には、水温計３８が設けられており、加速冷却装置３０に供給する冷却水の温度を計測できるように構成されている。水温計３８で計測した水温値は、プロセスコンピュータの制御盤４０に入力されるよう構成されている。制御盤４０には、貯留槽３４との間で冷却水を循環させて冷却する冷却水冷却装置４２が接続されている。制御盤４０は、水温計３８で計測した水温値がプロセスコンピュータを構成する演算部４４から入力される目標温度となるように冷却水冷却装置４２をオンオフ制御する。 The cooling water supply path 32 is provided with a water temperature gauge 38 so that the temperature of the cooling water supplied to the acceleration cooling device 30 can be measured. The water temperature value measured by the water temperature gauge 38 is configured to be input to the control panel 40 of the process computer. The control panel 40 is connected to a cooling water cooling device 42 that circulates cooling water between the control tank 40 and cools it. The control panel 40 performs on / off control of the cooling water cooling device 42 so that the water temperature value measured by the water temperature gauge 38 becomes the target temperature input from the calculation unit 44 constituting the process computer.
演算部４４には加熱装置１４で加熱される鋼板１２の情報が鋼板情報として入力されるように構成されている。この鋼板情報としては、加熱する鋼板１２の厚み寸法（以下板厚）や、冷却水による冷却終了温度を示す冷却停止温度などが挙げられる。ここで、冷却停止温度とは、鋼板１２が加速冷却装置３０を通過して冷却水による冷却が終了する時点での鋼板１２の温度を示す。演算部４４は、この鋼板情報に基づいて、冷却時の目標温度を算出し、この目標温度を冷却水冷却装置４２の制御指令として制御盤４０に出力するように構成されている。 Information of the steel plate 12 heated by the heating device 14 is input to the calculation unit 44 as steel plate information. Examples of the steel plate information include a thickness dimension of the steel plate 12 to be heated (hereinafter referred to as a plate thickness), a cooling stop temperature indicating a cooling end temperature by cooling water, and the like. Here, the cooling stop temperature indicates the temperature of the steel plate 12 at the time when the steel plate 12 passes through the acceleration cooling device 30 and the cooling with the cooling water is finished. The calculation unit 44 is configured to calculate a target temperature at the time of cooling based on the steel plate information, and output the target temperature to the control panel 40 as a control command for the cooling water cooling device 42.
このような加速冷却装置３０で鋼板１２を冷却する場合、図２に示すように、鋼板１２の冷却に使用する冷却水の温度が沸騰現象（特に極小熱流束点）に影響を及ぼすことが知られている。具体的に遷移沸騰領域での不安定な冷却では、鋼板１２内に生ずる温度偏差により冷却後の鋼板１２の形状、材質が悪化する。このため、冷却水の温度を瞬時に調整して鋼板１２を核沸騰領域又は膜沸騰領域のみで冷却することが望ましい。 When cooling the steel plate 12 with such an accelerated cooling device 30, as shown in FIG. 2, it is known that the temperature of the cooling water used for cooling the steel plate 12 affects the boiling phenomenon (especially the minimum heat flux point). It has been. Specifically, in the unstable cooling in the transition boiling region, the shape and material of the cooled steel plate 12 are deteriorated due to the temperature deviation generated in the steel plate 12. For this reason, it is desirable to cool the steel plate 12 only in the nucleate boiling region or the film boiling region by adjusting the temperature of the cooling water instantaneously.
しかし、このような設備において、冷却水の温度を瞬時に調整することは困難であることから、冷却水の温度を積極的に制御して遷移沸騰領域を避けることは実施されず、常に一定の水温で鋼板１２を冷却していた。 However, since it is difficult to instantaneously adjust the temperature of the cooling water in such equipment, it is not possible to actively control the temperature of the cooling water to avoid the transition boiling region, and the constant temperature is always constant. The steel plate 12 was cooled with the water temperature.
ここで、板厚が厚く冷却停止温度が低い鋼板１２の場合は、低水温で冷却することにより、速く核沸騰に到達させることができる。また、板厚が薄く冷却停止温度が高い鋼板１２の場合は、高水温で冷却することにより、膜沸騰のみで冷却できる。すなわち、板厚が厚く冷却停止温度の低い鋼板１２は低水温で冷却し、板厚が薄く冷却停止温度が高い鋼板１２は高水温で冷却することで、遷移沸騰領域での冷却を極力回避できることに着目した。 Here, in the case of the steel plate 12 having a large plate thickness and a low cooling stop temperature, nucleate boiling can be reached quickly by cooling at a low water temperature. Further, in the case of the steel plate 12 having a thin plate thickness and a high cooling stop temperature, it can be cooled only by film boiling by cooling at a high water temperature. That is, the steel plate 12 having a large plate thickness and a low cooling stop temperature is cooled at a low water temperature, and the steel plate 12 having a thin plate thickness and a high cooling stop temperature is cooled at a high water temperature, so that cooling in the transition boiling region can be avoided as much as possible. Focused on.
そして、発明者らは誠意検討し、複数の鋼板１２を連続して冷却する冷却水の目標温度を次のように求め、冷却水温度が目標温度となるように制御することを見出した。これにより、冷却水を瞬時に温度調整する制御をしなくても、遷移沸騰領域での冷却を抑制し、冷却後の鋼板１２の形状、材質を向上することができる。 The inventors have sincerely studied and found the target temperature of cooling water for continuously cooling the plurality of steel plates 12 as follows and found that the cooling water temperature is controlled to be the target temperature. Thereby, even if it does not control to adjust the temperature of cooling water instantly, cooling in a transition boiling region can be controlled and the shape and material of steel plate 12 after cooling can be improved.
すなわち、個別の鋼板１２に用いる最適冷却水温度を過去の冷却実績より定めた第１評価指標に基づいて第１冷却水温度Ｔ１として求める。次に、鋼板１２毎に求められた第１冷却水温度Ｔ１を第２評価指標に適用して第２冷却水温度Ｔ２を求める。そして、この第２冷却水温度Ｔ２を目標温度として冷却水冷却装置４２を制御し、目標温度とした冷却水で前記鋼板１２を連続的に冷却する。 That is, the optimal cooling water temperature used for the individual steel plates 12 is obtained as the first cooling water temperature T1 based on the first evaluation index determined from the past cooling performance. Next, the 1st cooling water temperature T1 calculated | required for every steel plate 12 is applied to a 2nd evaluation parameter | index, and 2nd cooling water temperature T2 is calculated | required. Then, the cooling water cooling device 42 is controlled with the second cooling water temperature T2 as a target temperature, and the steel sheet 12 is continuously cooled with the cooling water having the target temperature.
第１評価指標としては、冷却後に矯正を要した割合を示す再矯正率が一例として挙げられる。この再矯正率は冷却後の鋼板１２の寸法変化が許容値を超えて矯正を必要とする鋼板数の割合である。鋼板１２の板厚及び冷却停止温度毎に再矯正率の最も低かった冷却水温度が過去の冷却実績から定められ、この冷却水温度がデータテーブル化され用いられる（図４参照）。また、第２評価指標としては、冷却後に矯正が予想される鋼板１２の本数を示す再矯正本数が一例として挙げられ、詳細は以下に示す。 As a 1st evaluation parameter | index, the re-correction rate which shows the ratio which required correction after cooling is mentioned as an example. This re-correction rate is the ratio of the number of steel plates that require correction because the dimensional change of the steel plate 12 after cooling exceeds an allowable value. The cooling water temperature with the lowest re-correction rate is determined from the past cooling results for each plate thickness and cooling stop temperature of the steel plate 12, and this cooling water temperature is used as a data table (see FIG. 4). Moreover, as a 2nd evaluation parameter | index, the re-correction number which shows the number of the steel plates 12 with which correction | amendment is anticipated after cooling is mentioned as an example, and the detail is shown below.
図３は、本実施形態の動作を示すフローチャートであり、プロセスコンピュータが予め記憶されたプログラムに従って動作を開始すると、演算部４４は加熱装置１４から鋼板情報を取得する（Ｓ１）。これにより、演算部４４は、加熱装置１４で加熱する鋼板１２の板厚や冷却停止温度を把握する。次に、演算部４４は、各鋼板１２を冷却する際に適した冷却水温度を、取得した板厚及び冷却停止温度に基づいて、予め記憶された図４の第１温度設定テーブル５０から求める（Ｓ２）。 FIG. 3 is a flowchart showing the operation of the present embodiment. When the process computer starts operation according to a program stored in advance, the calculation unit 44 acquires steel plate information from the heating device 14 (S1). Thereby, the calculating part 44 grasps | ascertains the plate | board thickness and cooling stop temperature of the steel plate 12 heated with the heating apparatus 14. FIG. Next, the calculating part 44 calculates | requires the cooling water temperature suitable when cooling each steel plate 12 from the 1st temperature setting table 50 of FIG. 4 memorize | stored previously based on the acquired board thickness and cooling stop temperature. (S2).
第１温度設定テーブル５０は、図４に示したように、冷却に適した冷却水温度が鋼板１２の板厚と冷却停止温度との関係で記憶されたデータ群であり、過去の冷却実績に基づいて冷却に適した冷却水温度が板厚及び冷却停止温度毎に設定されている。 As shown in FIG. 4, the first temperature setting table 50 is a data group in which the cooling water temperature suitable for cooling is stored in relation to the plate thickness of the steel plate 12 and the cooling stop temperature. Based on this, a cooling water temperature suitable for cooling is set for each plate thickness and cooling stop temperature.
この第１温度設定テーブル５０の設定手順としては、例えば、板厚が５０ｍｍ以上６０ｍｍ未満、冷却停止温度が５００℃以上６００℃未満の複数の鋼板１２をそれぞれ異なる冷却水温度（図４では、右側の棒グラフで示すように３０℃〜３８℃）で冷却した場合の冷却後に必要な再矯正率を記録する。その結果、図４の右側の棒グラフに示されるように、矯正を要する再矯正率が３６℃の冷却水で冷却した鋼板１２が最も低い（１２％）。このため、第１温度設定テーブル５０の板厚が５０ｍｍ以上６０ｍｍ未満、冷却停止温度が５００℃以上６００℃未満の欄に、冷却水温度「３６℃」を設定する。このような手順を繰り返して、図４に示されるように各鋼板１２と冷却停止温度における第１温度設定テーブル５０を作成する。このとき、第１冷却水温度Ｔ１を求める対象となる鋼板１２は、３０分を単位として冷却処理される数の鋼板１２とする。 As a setting procedure of the first temperature setting table 50, for example, a plurality of steel plates 12 having a plate thickness of 50 mm or more and less than 60 mm and a cooling stop temperature of 500 ° C. or more and less than 600 ° C. are respectively set to different cooling water temperatures (in FIG. Record the re-correction rate required after cooling when cooling at 30 ° C. to 38 ° C. as shown in the bar graph of FIG. As a result, as shown in the bar graph on the right side of FIG. 4, the steel sheet 12 cooled with cooling water having a re-correction rate requiring correction of 36 ° C. is the lowest (12%). Therefore, the cooling water temperature “36 ° C.” is set in a column where the plate thickness of the first temperature setting table 50 is 50 mm or more and less than 60 mm and the cooling stop temperature is 500 ° C. or more and less than 600 ° C. Such a procedure is repeated to create the first temperature setting table 50 for each steel plate 12 and the cooling stop temperature as shown in FIG. At this time, the steel plates 12 for which the first cooling water temperature T1 is obtained are the number of steel plates 12 to be cooled in units of 30 minutes.
この第１温度設定テーブル５０を用いることによって、各鋼板１２を冷却する際に最適となる冷却水温度が、第１冷却水温度Ｔ１として鋼板１２の板厚と冷却停止温度ごとに求められる。 By using the first temperature setting table 50, the optimum cooling water temperature when cooling each steel plate 12 is obtained as the first cooling water temperature T1 for each plate thickness and cooling stop temperature of the steel plate 12.
これにより、３０分の処理単位で対象となる複数の鋼板１２を、単にその板厚や冷却停止温度だけではなく、再矯正率を加味して冷却に適した冷却水温度によって分類することができる。この分類は、過去の冷却実績において再矯正率が低かった冷却水温度とされており、再矯正率が最も低かったことから、遷移沸騰領域での冷却を回避できる冷却水温度と考えられる。このため、この第１冷却水温度Ｔ１を以降の処理で用いることで、遷移沸騰領域での冷却の回避を優先させた冷却水温度の算出が可能となる。 Thereby, the plurality of steel plates 12 to be processed in a processing unit of 30 minutes can be classified not only based on the plate thickness and the cooling stop temperature but also based on the cooling water temperature suitable for cooling in consideration of the recorrection rate. . This classification is considered to be the cooling water temperature at which the recorrection rate was low in the past cooling performance, and the recorrection rate was the lowest, so that it can be considered as the cooling water temperature at which cooling in the transition boiling region can be avoided. For this reason, by using this first cooling water temperature T1 in the subsequent processing, it becomes possible to calculate the cooling water temperature giving priority to avoiding the cooling in the transition boiling region.
なお、本実施形態では、各鋼板１２の冷却水温度を求める為の第１評価指標として、再矯正率を用いたが、これに限定されるものではない。この第１評価指標としては、冷却した鋼板１２の現れた最大波高さや、最大歪量や、材質合格率や、再矯正時間などを用いることができる。 In the present embodiment, the re-correction rate is used as the first evaluation index for determining the cooling water temperature of each steel plate 12, but the present invention is not limited to this. As the first evaluation index, the maximum wave height at which the cooled steel plate 12 appears, the maximum strain amount, the material pass rate, the re-correction time, and the like can be used.
次に、演算部４４は、ステップ（Ｓ２）で求めた第１冷却水温度Ｔ１から、３０分間冷却処理する間に継続して使用する冷却水温度を求める為の第２評価指標が最適となるような第２冷却水温度Ｔ２を算出する（Ｓ３）。 Next, the calculation unit 44 uses the first evaluation index for obtaining the cooling water temperature to be continuously used during the cooling process for 30 minutes from the first cooling water temperature T1 obtained in step (S2). Such second cooling water temperature T2 is calculated (S3).
すなわち、演算部４４には、第１冷却水温度Ｔ１の鋼板１２を複数の冷却水温度で冷却した場合の１本当たりの再矯正本数が再矯正率Ｐとして図４で示される第１冷却水温度Ｔ１毎に予め記憶されている。例えば第１冷却水温度Ｔ１が３０℃の鋼板１２を３０℃の冷却水で冷却した場合の再矯正率Ｐが「０．１」、３２℃の場合が「０．１２」、３４℃の場合が「０．１６」、３６℃の場合が「０．１７」、３８℃の場合が「０．１８」として記憶されている。 In other words, the calculation unit 44 includes the first cooling water in which the number of re-corrections per one when the steel sheet 12 having the first cooling water temperature T1 is cooled at a plurality of cooling water temperatures is shown in FIG. Prestored for each temperature T1. For example, when the steel sheet 12 having a first cooling water temperature T1 of 30 ° C. is cooled with 30 ° C. cooling water, the re-correction rate P is “0.1”, 32 ° C. is “0.12”, and 34 ° C. Is “0.16”, 36 ° C. is stored as “0.17”, and 38 ° C. is stored as “0.18”.
そして、演算部４４では、図５に示すように、鋼板情報毎に各目標温度候補Ｔｉでの再矯正本数Ｅが次式で算出され、第２温度設定テーブル５２が形成される。なお、目標温度候補Ｔｉは、第２冷却水温度Ｔ２を選択するための候補温度である。
再矯正本数Ｅ＝再矯正率Ｐ×鋼板の本数Ｎ
And in the calculating part 44, as shown in FIG. 5, the re-correction number E in each target temperature candidate Ti is calculated by following Formula for every steel plate information, and the 2nd temperature setting table 52 is formed. The target temperature candidate Ti is a candidate temperature for selecting the second cooling water temperature T2.
Number of re-correction E = Re-correction rate P × Number of steel sheets N
第１温度設定テーブル５０に基づいて分類された結果、第１冷却水温度Ｔ１が「３０℃」とされた鋼板１２の本数Ｎが「１０」の場合、前述したように演算部４４には、第１冷却水温度Ｔ１が「３０℃」の鋼板１２を「３０℃」の冷却水で冷却した際の再矯正率Ｐが「０．１」と記憶されている。そして、第１冷却水温度Ｔ１が「３０℃」とされた鋼板１２の本数Ｎは「１０」なので、再矯正本数Ｅは「１」（Ｐ（０．１）×Ｎ（１０））として第２温度設定テーブル５２に設定される。同様に、第１冷却水温度Ｔ１が「３０℃」の鋼板１２を「３２℃」の冷却水で冷却した際の再矯正率Ｐは「０．１２」と記憶されており、第１冷却水温度Ｔ１が「３０℃」とされた鋼板１２の本数Ｎは「１０」である。このため、再矯正本数Ｅは「１．２」（Ｐ（０．１２）×Ｎ（１０））として第２温度設定テーブル５２に設定される。以下同じように図５の再矯正本数Ｅが定められる。 As a result of the classification based on the first temperature setting table 50, when the number N of the steel plates 12 in which the first cooling water temperature T1 is “30 ° C.” is “10”, as described above, The re-correction rate P is stored as “0.1” when the steel sheet 12 having the first cooling water temperature T1 of “30 ° C.” is cooled with the cooling water of “30 ° C.”. Since the number N of the steel plates 12 having the first cooling water temperature T1 of “30 ° C.” is “10”, the re-correction number E is “1” (P (0.1) × N (10)). 2 is set in the temperature setting table 52. Similarly, the re-correction rate P when the steel plate 12 having the first cooling water temperature T1 of “30 ° C.” is cooled with the cooling water of “32 ° C.” is stored as “0.12”, and the first cooling water is stored. The number N of the steel plates 12 having the temperature T1 of “30 ° C.” is “10”. For this reason, the number E of recorrections is set to “1.2” (P (0.12) × N (10)) in the second temperature setting table 52. Hereinafter, the number E of recorrections in FIG. 5 is determined in the same manner.
この第２温度設定テーブル５２では、目標温度候補Ｔｉ毎に再矯正本数Ｅの合計値（
再矯正本数合計）が算出されており、各目標温度候補Ｔｉのうち合計値が最も少ない目標温度候補Ｔｉが第２冷却水温度Ｔ２として選択され、この第２冷却水温度Ｔ２が目標温度として制御盤４０に送信される。これにより、３０分の処理単位で対象となる鋼板１２において、冷却後の再矯正率が全体として最も低くなる冷却水温度を目標温度として選択し、制御盤４０に送信することができる。
In the second temperature setting table 52, the total number of re-correction lines E for each target temperature candidate Ti (
(Total number of re-corrections) is calculated, and among the target temperature candidates Ti, the target temperature candidate Ti having the smallest total value is selected as the second cooling water temperature T2, and the second cooling water temperature T2 is controlled as the target temperature. It is transmitted to the board 40. Thereby, in the steel plate 12 which is a target in a processing unit of 30 minutes, the cooling water temperature at which the recorrection rate after cooling becomes the lowest as a whole can be selected as the target temperature and transmitted to the control panel 40.
なお、本実施形態では、３０分間で冷却処理する間に継続して使用される冷却水温度を求める為の第２評価指標として、再矯正本数Ｅを用いたが、これに限定されるものではない。この第２評価指標としては、処理単位で冷却される鋼板１２の最大波高さの平均値や、最大歪量の平均値や、材質合格率や、材質合格本数や、再矯正時間（再矯正にかかる負荷）の平均値や、生じた歪の急峻度や、歪量を用いることができる。つまり、低減したい指標（例えば、材質の不合格率の低減を図りたい場合には材質不合率）を第２評価指標として用いることで、目的とした効果を高めることができる。 In this embodiment, the re-correction number E is used as the second evaluation index for obtaining the cooling water temperature continuously used during the cooling process for 30 minutes. However, the present invention is not limited to this. Absent. As the second evaluation index, the average value of the maximum wave height of the steel sheet 12 cooled in the processing unit, the average value of the maximum strain, the material pass rate, the number of material passes, the re-correction time (for re-correction) The average value of such load), the steepness of the generated distortion, and the amount of distortion can be used. That is, the target effect can be enhanced by using the index to be reduced (for example, the material mismatch rate when reducing the reject rate of the material) as the second evaluation index.
そして、演算部４４は、第２冷却水温度Ｔ２を目標温度として制御盤４０に出力し（Ｓ４）、制御盤４０は、水温計３８で計測した水温値が目標温度となるように冷却水冷却装置４２をオンオフ制御する（Ｓ５）。これにより、貯留槽３４に貯留された冷却水は目標温度となり、この冷却水によって鋼板１２が冷却される。 Then, the calculation unit 44 outputs the second cooling water temperature T2 as a target temperature to the control panel 40 (S4), and the control panel 40 cools the cooling water so that the water temperature value measured by the water temperature gauge 38 becomes the target temperature. The device 42 is on / off controlled (S5). Thereby, the cooling water stored in the storage tank 34 becomes a target temperature, and the steel plate 12 is cooled by this cooling water.
この状態で対象となる鋼板１２を目標温度の冷却水で連続的に冷却する。そして、冷却水温度が目標温度となるように冷却水冷却装置４２の制御を開始してから３０分経過し、処理単位の鋼板１２の冷却が終了する又は終了に近づいた際には（Ｓ６）、次の３０分間で冷却される鋼板１２の冷却水温度を再計算し、目標温度を更新する（Ｓ１〜Ｓ４）。 In this state, the target steel plate 12 is continuously cooled with the cooling water of the target temperature. Then, 30 minutes have passed since the control of the cooling water cooling device 42 was started so that the cooling water temperature became the target temperature, and when the cooling of the steel plate 12 in the processing unit is finished or is nearing the end (S6). Then, the cooling water temperature of the steel plate 12 cooled in the next 30 minutes is recalculated, and the target temperature is updated (S1 to S4).
これにより、加速冷却装置３０で使用する冷却水の温度を、経過時間で変化させることができる。図６には、加速冷却装置３０で使用する冷却水の温度を３０分毎に変更した際の経過時間と冷却水温度との関係が示されている。このように、同一の加速冷却装置３０において、経過時間に応じて異なる冷却水温度で鋼板１２を冷却することができる。 Thereby, the temperature of the cooling water used with the acceleration cooling device 30 can be changed with elapsed time. FIG. 6 shows the relationship between the elapsed time and the cooling water temperature when the temperature of the cooling water used in the acceleration cooling device 30 is changed every 30 minutes. Thus, in the same accelerated cooling device 30, the steel plate 12 can be cooled at different cooling water temperatures depending on the elapsed time.
そして、冷却水温度が３４度未満の低水温による冷却時には、核沸騰領域優位の冷却を行うことができる。また、冷却水温度が３４度以上の高水温による冷却時には、膜沸騰領域優位の冷却を行うことができる。このように、３０分毎に冷却される鋼板１２に応じて、遷移沸騰領域での冷却を極力回避した適切な冷却を行うことができる。 And at the time of cooling by the low water temperature whose cooling water temperature is less than 34 degree | times, cooling of a nucleate boiling area | region can be performed. In addition, when cooling at a high water temperature of 34 ° C. or higher, the film boiling region can be cooled. Thus, according to the steel plate 12 cooled every 30 minutes, the appropriate cooling which avoided the cooling in a transition boiling area | region as much as possible can be performed.
なお、本実施形態では、処理単位を一定の処理時間である３０分と定め、３０分毎に第２冷却水温度Ｔ２を求めて更新する場合を例に挙げて説明したが、これに限定されるものではない。例えば、処理単位を冷却する鋼板１２の数や任意の処理時間で定め、この処理単位毎に第２冷却水温度Ｔ２を求めて更新しても良い。 In the present embodiment, the case where the processing unit is set to a certain processing time of 30 minutes and the second cooling water temperature T2 is obtained and updated every 30 minutes has been described as an example, but the present invention is not limited thereto. It is not something. For example, the processing unit may be determined by the number of steel plates 12 to be cooled or an arbitrary processing time, and the second cooling water temperature T2 may be obtained and updated for each processing unit.
図８には、板厚や冷却停止温度が異なる複数の鋼板１２を同じ冷却水温度で冷却した比較例での再矯正率と、冷却する複数の鋼板１２の情報に応じて冷却水温度を設定する本実施形態の冷却方法で冷却した場合の再矯正率とが示されている。この図から本実施形態の冷却方法で冷却した鋼板１２では、比較例で冷却した鋼板１２と比較して、再矯正率が２％改善されたことがわかる。 In FIG. 8, the cooling water temperature is set according to the re-correction rate in the comparative example in which the plurality of steel plates 12 having different thicknesses and cooling stop temperatures are cooled at the same cooling water temperature, and information on the plurality of steel plates 12 to be cooled. The re-correction rate when cooled by the cooling method of the present embodiment is shown. From this figure, it can be seen that in the steel plate 12 cooled by the cooling method of the present embodiment, the re-correction rate was improved by 2% compared to the steel plate 12 cooled in the comparative example.
このように、本実施形態では、冷却水を瞬時に温度調整する制御を避けつつ、３０分間で処理される鋼板１２全体として遷移沸騰領域での冷却を抑制することで、板内温度偏差の発生を抑制し、冷却後の鋼板１２の形状を安定化させることができる。これにより、冷却後の鋼板１２の形状、材質の向上を図ることができる。 As described above, in this embodiment, the temperature in the transition boiling region is suppressed as the entire steel plate 12 processed in 30 minutes while avoiding the control of instantaneously adjusting the temperature of the cooling water, thereby generating the temperature deviation in the plate. And the shape of the steel plate 12 after cooling can be stabilized. Thereby, the shape and material of the steel plate 12 after cooling can be improved.
（他の実施形態）
図７は、他の実施形態を示す図であり、図３のフローチャートのステップＳ３で用いられる第２温度設定テーブル５２のみが異なるため、変更された第２温度設定テーブル５２Ｂと関連する部分についてのみ説明する。
(Other embodiments)
Figure 7 is a diagram showing another embodiment, only the second temperature setting table 52 used in the step S3 of the flowchart of FIG. 3 ing different, the portion associated with the second temperature setting table 52B that have changed Only explained.
すなわち、演算部４４では、鋼板情報毎に各目標温度候補Ｔｉでの減点数Ｅが、次式で算出され、第２温度設定テーブル５２Ｂが形成される。
減点数Ｅ＝|目標温度候補Ｔｉ−第１冷却水温度Ｔ１|×鋼板１２の本数Ｎ
That is, the calculation unit 44 calculates a deduction point E for each target temperature candidate Ti for each steel plate information by the following equation, and forms the second temperature setting table 52B.
Deduction point E = | target temperature candidate Ti−first cooling water temperature T1 | × number N of steel plates 12
例えば第１冷却水温度Ｔ１が「３０℃」の鋼板１２において、その本数Ｎが「１０」の場合、目標温度候補Ｔｉが３０℃の欄には「０」、３２℃の欄には「２０」、３４℃の欄には「４０」、３６℃の欄には「６０」、３８℃の欄には「８０」が設定されている。以下同じように図７の減点数Ｅが定められる。 For example, when the number N of the steel plates 12 having the first cooling water temperature T1 of “30 ° C.” is “10”, the target temperature candidate Ti is “0” in the column of 30 ° C. and “20” in the column of 32 ° C. “,” “40” is set in the 34 ° C. column, “60” is set in the 36 ° C. column, and “80” is set in the 38 ° C. column. Thereafter, the deduction number E in FIG. 7 is determined in the same manner.
この第２温度設定テーブル５２Ｂでは、目標温度候補Ｔｉ毎に減点数Ｅの合計値（減点数合計）が算出されており、この合計値が最も少ない目標温度候補Ｔｉが第２冷却水温度Ｔ２として選択され、制御盤４０に出力される。なお、本実施形態では、目標温度候補Ｔｉと第１冷却水温度Ｔ１との温度差に鋼板１２の本数Ｎを乗算して得た減点数Ｅが第２評価指標として用いられている。 In the second temperature setting table 52B, the total value of the deduction points E (total deduction points) is calculated for each target temperature candidate Ti, and the target temperature candidate Ti having the smallest total value is set as the second cooling water temperature T2. Is selected and output to the control panel 40. In the present embodiment, a deduction number E obtained by multiplying the temperature difference between the target temperature candidate Ti and the first cooling water temperature T1 by the number N of the steel plates 12 is used as the second evaluation index.
この第２温度設定テーブル５２Ｂを用いて各鋼板１２を冷却した場合にも、図８と同様の効果が得られ、本実施形態の冷却方法で冷却した鋼板１２では、比較例で冷却した鋼板１２と比較して、再矯正率が２％改善されることを確認できた。 Even when each steel plate 12 is cooled using the second temperature setting table 52B, the same effect as in FIG. 8 is obtained. In the steel plate 12 cooled by the cooling method of the present embodiment, the steel plate 12 cooled in the comparative example is obtained. It was confirmed that the re-correction rate was improved by 2% compared with.
１２ 鋼板
１４ 加熱装置
１８ 圧延装置
３０ 加速冷却装置
４０ 制御盤
４２ 冷却水冷却装置
４４ 演算部
５０ 第２温度設定テーブル
５２ 第２温度設定テーブル
５２Ｂ 第２温度設定テーブル
12 Steel plate 14 Heating device 18 Rolling device 30 Accelerated cooling device 40 Control panel 42 Cooling water cooling device 44 Operation unit 50 Second temperature setting table 52 Second temperature setting table 52B Second temperature setting table
Claims (6)
前記処理単位のうちの個別の鋼板に用いる最適冷却水温度を過去の冷却実績より定めた第１評価指標に基づいて求め、
前記処理単位で冷却する複数の鋼板を、前記第１評価指標に基づいて求めた前記最適冷却水温度毎に分類し、分類された鋼板毎に複数の目標温度候補で冷却した場合の優劣を数値化した第２評価指標を求め、
前記目標温度候補毎に前記第２評価指標を合計した合計値を求め、
前記目標温度候補毎に合計された各合計値に基づいて各目標温度候補の中から前記処理単位を通じて用いる冷却水の目標温度を求め、
前記処理単位で冷却する際の冷却水温度が前記目標温度となるように制御する冷却方法。 A cooling method for controlling a cooling water temperature when cooling a plurality of hot-rolled steel plates for each predetermined processing unit,
Finding the optimum cooling water temperature to be used for individual steel plates in the processing unit based on the first evaluation index determined from the past cooling performance,
A plurality of steel plates to be cooled in the processing unit are classified according to the optimum cooling water temperature obtained based on the first evaluation index, and numerical values indicate superiority or inferiority when cooled by a plurality of target temperature candidates for each classified steel plate. For the second evaluation index,
A total value obtained by summing up the second evaluation indexes for each target temperature candidate is obtained,
Obtaining the target temperature of the cooling water to be used through the processing unit from each target temperature candidate based on each total value summed for each target temperature candidate,
The cooling method which controls so that the cooling water temperature at the time of cooling by the said process unit may become the said target temperature.
該加熱工程で加熱された鋼片を圧延して鋼板とする圧延工程と、
該圧延工程で圧延された鋼板を、請求項１から５にいずれか記載の冷却方法で冷却する冷却工程と、
を備える鋼板の製造方法。 A heating step for heating the billet,
A rolling step of rolling the steel slab heated in the heating step into a steel plate;
A cooling step of cooling the steel sheet rolled in the rolling step by the cooling method according to any one of claims 1 to 5,
The manufacturing method of the steel plate provided with.
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