JP6447836B2 - Hot-rolled steel strip manufacturing method and hot-rolled steel strip manufacturing equipment - Google Patents
Hot-rolled steel strip manufacturing method and hot-rolled steel strip manufacturing equipment Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims description 60
- 239000010959 steel Substances 0.000 title claims description 60
- 238000004519 manufacturing process Methods 0.000 title claims description 48
- 238000001816 cooling Methods 0.000 claims description 258
- 238000005096 rolling process Methods 0.000 claims description 246
- 239000000463 material Substances 0.000 claims description 76
- 230000002441 reversible effect Effects 0.000 claims description 69
- 238000012937 correction Methods 0.000 claims description 68
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 62
- 238000010583 slow cooling Methods 0.000 claims description 51
- 238000002347 injection Methods 0.000 claims description 35
- 239000007924 injection Substances 0.000 claims description 35
- 238000004364 calculation method Methods 0.000 claims description 27
- 230000009466 transformation Effects 0.000 claims description 24
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- 230000009467 reduction Effects 0.000 claims description 6
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- 238000010791 quenching Methods 0.000 claims description 4
- 230000000171 quenching effect Effects 0.000 claims description 4
- 239000000498 cooling water Substances 0.000 description 29
- 230000002829 reductive effect Effects 0.000 description 14
- 230000005855 radiation Effects 0.000 description 9
- 239000007921 spray Substances 0.000 description 9
- 230000008569 process Effects 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 7
- 229910000859 α-Fe Inorganic materials 0.000 description 7
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- 230000000052 comparative effect Effects 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000004513 sizing Methods 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 229910001035 Soft ferrite Inorganic materials 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
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Description
本発明は、特に１２ｍｍ以上の厚みを持ち、且つ高靭性が要求される熱延鋼帯の製造において、粗圧延時に冷却装置によりシートバーの冷却を行う熱延鋼帯の製造方法および熱延鋼帯の製造設備に関するものである。 The present invention relates to a method for producing a hot-rolled steel strip and a hot-rolled steel in which a sheet bar is cooled by a cooling device during rough rolling in the production of a hot-rolled steel strip having a thickness of 12 mm or more and high toughness. It relates to the production equipment of the belt.
図１１には一般的な熱延工程が示されており、この圧延工程では、まず連続加熱炉1により１２００℃程度まで加熱された被圧延材（スラブ）をサイジングプレス２により板幅方向に鍛造することで板幅を調整し、次いでこの被圧延材を粗圧延機群３により圧延して厚み３０〜５０ｍｍのシートバー１０とし、続いてこのシートバー１０を連続圧延可能な６〜７スタンドの仕上げ圧延機群６により１．２〜２５ｍｍまで圧延して圧延鋼帯とし、次いでランアウトテーブル７により冷却してコイラー８で巻き取る。 FIG. 11 shows a general hot rolling process. In this rolling process, a material to be rolled (slab) heated to about 1200 ° C. by a continuous heating furnace 1 is first forged in a sheet width direction by a sizing press 2. The sheet width is then adjusted, and then the material to be rolled is rolled by the rough rolling mill group 3 to form a sheet bar 10 having a thickness of 30 to 50 mm, and then the sheet bar 10 is continuously rolled for 6 to 7 stands. A rolled steel strip is rolled to 1.2 to 25 mm by a finish rolling mill group 6 and then cooled by a run-out table 7 and wound by a coiler 8.
熱延鋼板のうち、ラインパイプに代表される構造用鋼板は８〜２５ｍｍの厚みを有し、特に寒冷地向けラインパイプ素材のように強度と靭性が重視されるものは、圧延工程において制御圧延（Controlled-Rollｉng；CR）が実施されることが多い。制御圧延とは、鋼の結晶粒の成長速度が遅い低温条件下で圧延することで、結晶組織を微細化し靭性を向上させる技術である。制御圧延を開始する温度（制御圧延開始温度）は、ＮｂやＶなどの添加元素により異なるが、おおよそ９５０℃以下であり、制御圧延開始時の板厚から製品厚みになるまで少なくとも６０％程度の圧下率で圧延を行う。例えば、圧下率６０％で制御圧延を行う場合、製品厚みが２５ｍｍとすると、制御圧延開始時の厚みは６３ｍｍであり、粗圧延機群３では、厚み例えば２５０ｍｍのスラブから厚み６３ｍｍのシートバーとなるまで圧延を行う必要がある。 Among hot-rolled steel sheets, structural steel sheets typified by line pipes have a thickness of 8 to 25 mm, and especially those that emphasize strength and toughness, such as line pipe materials for cold regions, are controlled rolling in the rolling process. (Controlled-Rolling; CR) is often implemented. Controlled rolling is a technique for refining the crystal structure and improving toughness by rolling under low temperature conditions where the growth rate of steel crystal grains is slow. The temperature at which controlled rolling is started (controlled rolling start temperature) varies depending on additive elements such as Nb and V, but is approximately 950 ° C. or less, and is at least about 60% from the plate thickness at the start of controlled rolling to the product thickness. Rolling is performed at a reduction rate. For example, when controlled rolling is performed at a rolling reduction of 60%, if the product thickness is 25 mm, the thickness at the start of controlled rolling is 63 mm. In the rough rolling mill group 3, a sheet bar having a thickness of, for example, 250 mm and a thickness of 63 mm It is necessary to roll until it becomes.
そのために、まず粗圧延機群３で粗圧延終了までにシートバー１０の厚みが所定の制御圧延開始板厚となるよう粗圧延を行い、次いでシートバー１０の中心温度が９５０℃以下となるまで仕上げ圧延機群６の前でシートバー１０を空冷待機させ、その後仕上げ圧延機群６で圧延する手法がとられる。この際に、仕上げ圧延機群６の前でシートバー１０を待機させる時間は２００〜３００秒程度必要であるため、この間に次材を圧延することが出来ず圧延能率が大きく低下する。熱延鋼帯の製造ラインに関して、待機時間の問題を解決するための先行文献は少ないが、厚鋼板の製造ラインでは数多く検討されており、例えば以下のような技術が開示されている。 Therefore, first, rough rolling is performed in the rough rolling mill group 3 so that the thickness of the sheet bar 10 reaches a predetermined control rolling start plate thickness until the end of the rough rolling, and then the center temperature of the sheet bar 10 becomes 950 ° C. or less. A method is adopted in which the sheet bar 10 is air-cooled on standby before the finish rolling mill group 6 and then rolled by the finish rolling mill group 6. At this time, since it takes about 200 to 300 seconds to wait for the sheet bar 10 in front of the finish rolling mill group 6, the next material cannot be rolled during this time, and the rolling efficiency is greatly reduced. Although there are few prior literatures for solving the problem of waiting time for a hot-rolled steel strip production line, many studies have been made on thick steel plate production lines. For example, the following techniques are disclosed.
特許文献１に記載の技術は、可逆式の粗圧延機の入側若しくは出側に１５〜３００℃／秒程度の冷却装置を設置し、粗圧延機の圧延パスのパス間で冷却を実施することにより、つまり制御圧延開始厚みよりも板厚みが厚い段階で上記冷却装置により被圧延材の水冷を実施することにより、制御圧延開始までに目標の制御圧延開始温度にする技術である。しかしこの技術は、冷却速度が高く且つ板厚みが大きい場合は、鋼材の表面と中心の温度差が大きくなり、水冷中にシートバーの表層がフェライト相変態温度（フェライト相変態が始まる温度）を下回る可能性がある。シートバーの表層が相変態温度を下回った場合、シートバーの表層においてオーステナイト組織からフェライト組織への相変態が起こり、この状態で圧延を行うと軟質であるフェライト粒界に歪みが集中して表層割れが発生する可能性がある。 The technique described in Patent Document 1 installs a cooling device of about 15 to 300 ° C./second on the entry side or the exit side of a reversible roughing mill, and performs cooling between passes of the rolling pass of the roughing mill. In other words, this is a technique for achieving the target controlled rolling start temperature by the start of controlled rolling by performing water cooling of the material to be rolled by the cooling device at a stage where the plate thickness is thicker than the controlled rolling start thickness. However, in this technology, when the cooling rate is high and the plate thickness is large, the temperature difference between the surface and the center of the steel material increases, and the surface layer of the sheet bar changes the ferrite phase transformation temperature (the temperature at which the ferrite phase transformation begins) during water cooling. It may be lower. When the surface layer of the sheet bar falls below the phase transformation temperature, a phase transformation from the austenite structure to the ferrite structure occurs in the surface layer of the sheet bar, and when rolling is performed in this state, strain concentrates on the soft ferrite grain boundary and the surface layer Cracks may occur.
特許文献２に記載の技術は、複数の被圧延材を同時に圧延する手法に関するものであり、制御圧延前の厚みまで圧延が完了した後に、被圧延材を一旦圧延機から遠方の搬送テーブル上で待機させておき、その間に次材の圧延を実施することで、圧延機のアイドリング時間を極小化する技術である。しかし本技術は、制御圧延開始までの空冷による待機時間と圧延時間がほぼ一致しているときには能率向上効果が大きいものの、大きく異なる場合は圧延能率があまり上がらないという問題がある。 The technique described in Patent Document 2 relates to a method for simultaneously rolling a plurality of rolled materials, and after rolling is completed to a thickness before controlled rolling, the rolled material is temporarily moved on a transport table far from the rolling mill. This is a technique for minimizing the idling time of the rolling mill by allowing the next material to be rolled during that time. However, this technique has a problem that although the efficiency improvement effect is large when the waiting time by air cooling until the start of controlled rolling and the rolling time are substantially the same, the rolling efficiency does not increase so much when they are greatly different.
特許文献３には、制御圧延前の圧延が完了した鋼板を、次の被圧延材が通過できる高さに持ち上げて待機状態に保持する片持ちフォーク状のアームを有する昇降装置が開示されている。シートバーの厚みが十分厚く、且つ待機させるシートバーの待機時間が通過させるシートバーの圧延時間と一致している時には非常に有用な技術である。一方、熱延鋼帯では、厚鋼板と比較してスラブの重量が２０〜３０トンと大きく、またシートバーの長さが例えば２０ｍを超えるなど極めて長くなることから、大規模な昇降装置が必要になる。また、昇降装置のアームとシートバーが長時間接するため、その接触部の温度が低くなるという問題もある。さらに、待機装置を用いて次材を追い越して圧延を行うことができることが示唆されているが、冷却待ちを要する制御圧延材が含まれている場合に、どのように圧延を行えば、熱間圧延機の空き時間を低減して、圧延能率を向上させることができるかについては示されていない。 Patent Document 3 discloses a lifting device having a cantilevered fork-like arm that lifts a steel plate that has been rolled before controlled rolling to a height that allows the next material to be rolled to pass through and holds it in a standby state. . This is a very useful technique when the thickness of the sheet bar is sufficiently thick and matches the rolling time of the sheet bar through which the waiting time of the waiting sheet bar passes. On the other hand, in the hot-rolled steel strip, the weight of the slab is as large as 20 to 30 tons compared to the thick steel plate, and the length of the seat bar is extremely long, for example, exceeding 20 m, so a large lifting device is required. become. Moreover, since the arm of the lifting device and the seat bar are in contact with each other for a long time, there is a problem that the temperature of the contact portion is lowered. Furthermore, although it has been suggested that rolling can be performed by overtaking the next material using a standby device, if a controlled rolling material that requires waiting for cooling is included, It is not shown whether the idle time of the rolling mill can be reduced and the rolling efficiency can be improved.
特許文献４には、上記文献の弱点を補強するために、特許文献３の昇降装置に加えて、圧延機の前後に水冷装置を設置することが開示されている。しかし本文献にも、特許文献３と同様、様々なサイズおよび温度条件のシートバーに対してどのように圧延を行えば、熱間圧延機の空き時間を低減して、圧延能率を向上させることができるかについては示されていない。 Patent Document 4 discloses that in order to reinforce the weak point of the above-mentioned document, in addition to the lifting device of Patent Document 3, water cooling devices are installed before and after the rolling mill. However, in this document as well as Patent Document 3, if rolling is performed on sheet bars of various sizes and temperature conditions, the idle time of the hot rolling mill is reduced and the rolling efficiency is improved. It is not shown whether it can.
そこで、本発明者らが、熱延鋼帯の製造ラインに関して、上記の問題を解決するため鋭意研究を行った結果、粗圧延機群の複数の圧延機のうち少なくとも１機を可逆式圧延機とすると共に、この可逆式圧延機の上流側または下流側に、圧延方向に互いに隣り合って配置された水量密度１０００Ｌ／ｍｉｎ・ｍ２以上の急冷却装置と水量密度１０００Ｌ／ｍｉｎ・ｍ２未満の緩冷却装置とからなる冷却装置を設け、可逆圧延機の圧延パスに関連して、シートバーの板厚が比較的大きい圧延パスでは緩冷却装置による緩冷却を行い、シートバーの板厚が比較的小さい圧延パスでは急冷却装置による急冷却を行うことで、シートバーの表層が相変態温度（例えば６００℃）を下回ることを防止しつつ、制御圧延開始までに要する時間を低減して能率よく熱延鋼帯を製造することに成功した。 Therefore, as a result of intensive studies to solve the above problems, the present inventors have made at least one of a plurality of rolling mills of the rough rolling mill group a reversible rolling mill. And a rapid cooling device with a water density of 1000 L / min · m 2 or more and a water density of less than 1000 L / min · m 2 arranged adjacent to each other in the rolling direction on the upstream side or downstream side of the reversible rolling mill. In connection with the rolling pass of the reversible rolling mill, a slow cooling is performed by the slow cooling device in the rolling pass where the plate thickness of the sheet bar is relatively large. In a relatively small rolling pass, rapid cooling by a rapid cooling device prevents the surface layer of the sheet bar from falling below the phase transformation temperature (for example, 600 ° C.) and reduces the time required to start controlled rolling. It was able to be manufactured hot-rolled steel strip.
ところで、粗圧延工程には、シートバーの表層の酸化スケールを除去するために１５ＭＰａ以上の高圧水をシートバー上面に噴射するデスケーリング工程や、冷却水の吹き付けにより平均温度約６０〜８０℃に調整されたロールによる圧延工程、さらに上述したような冷却装置を用いた冷却工程も含まれるが、いずれの工程でもシートバーは表層から抜熱され、シートバーの表面温度は板厚方向の中心部より低くなる。板厚方向の温度勾配が生じると鋼板内部の伝熱作用により、一定時間経過すれば板厚方向の温度勾配は緩和される。この現象を復熱という。復熱には、粗圧延工程のシートバーの厚みにおいて３０秒〜６０秒程の時間を要するため、圧延能率の観点から、シートバーの表層の温度が回復するまでシートバーを待機させることは一般的に行われず、表層温度が低下したままの状態で粗圧延工程は継続される。 By the way, in the rough rolling process, in order to remove the oxide scale on the surface layer of the sheet bar, an average temperature of about 60 to 80 ° C. is achieved by a descaling process in which high-pressure water of 15 MPa or more is sprayed on the upper surface of the sheet bar or by blowing cooling water. The rolling process by the adjusted roll and the cooling process using the cooling device as described above are also included. In any process, the sheet bar is removed from the surface layer, and the surface temperature of the sheet bar is the center in the thickness direction. Lower. When a temperature gradient in the plate thickness direction occurs, the temperature gradient in the plate thickness direction is relaxed after a certain period of time due to the heat transfer action inside the steel plate. This phenomenon is called recuperation. Since recuperation requires a time of about 30 seconds to 60 seconds in the thickness of the sheet bar in the rough rolling step, it is common to wait the sheet bar until the temperature of the surface layer of the sheet bar recovers from the viewpoint of rolling efficiency. The rough rolling process is continued in a state where the surface layer temperature remains lowered.
一方、上記冷却装置を設置する目的は、シートバーの中心温度が圧延開示温度まで低下する時間を短縮することで圧延能率を向上させることであり、このために設備能力を最大活用できる条件は、表面温度を相変態温度（例えば６００℃）以上に保持するという制約下で最大の温度降下量が得られる条件となる。この条件を得るために、熱伝導方程式を差分近似した数値計算を解く差分法が用いられる。この際、シートバーからの熱損失として、デスケーリング処理や冷却装置による水冷、搬送期間中の空冷、圧延ロールとの接触等による種々の熱損失を考慮し、シートバーの板厚方向の断面温度分布を算出する。水冷による熱損失に関しては、水量密度とともにシートバー表面上の冷却水の噴射領域が大きく影響する。噴射領域は、冷却水用のヘッダーやノズルの設備上の配置により決まり、上記数値計算にも反映される。この数値計算により冷却中のシートバーの表面温度を予想し、相変態温度を下回らない範囲で冷却条件を調整する。シートバーを冷却装置に通過させながら冷却する場合、シートバーの搬送速度がセットアップ時の設定項目となる。 On the other hand, the purpose of installing the cooling device is to improve the rolling efficiency by shortening the time during which the center temperature of the sheet bar is lowered to the rolling disclosure temperature. The maximum temperature drop is obtained under the constraint that the surface temperature is maintained at or above the phase transformation temperature (for example, 600 ° C.). In order to obtain this condition, a difference method that solves a numerical calculation that approximates the heat conduction equation by difference is used. At this time, as heat loss from the sheet bar, taking into account various heat loss due to descaling processing, water cooling by a cooling device, air cooling during the conveyance period, contact with the rolling roll, etc., the cross-sectional temperature in the sheet bar thickness direction Calculate the distribution. Regarding the heat loss due to water cooling, the jet region of the cooling water on the surface of the seat bar greatly affects the water density. The injection area is determined by the arrangement of the cooling water header and nozzle on the equipment, and is reflected in the numerical calculation. By this numerical calculation, the surface temperature of the sheet bar during cooling is predicted, and the cooling conditions are adjusted within a range not lower than the phase transformation temperature. When cooling while passing the sheet bar through the cooling device, the sheet bar conveyance speed is a setting item at the time of setup.
しかしながら、実施の圧延ラインでは、上記数値計算には反映されない、シートバー表面温度の低下を誘発する不確定因子が存在する。例えば、デスケーリング処理中の水の飛散防止のために遮蔽板が用いられるが、種々の事情により漏洩水が発生することがあり、このような場合、漏洩水がデスケーリング設備の前後領域でシートバーの上面に滞留し、表面温度を低下させる原因となる。また、通常、圧延ロール用の冷却装置には、圧延ロールに吹き付ける冷却水がシートバーの表面に乗らないようにロール水切り装置が設けられるが、冷却水の一部が漏出することもある。また、前材（先に圧延されたシートバー）との間隔が狭くなると、シートバー同士の衝突を防ぐためにテーブル上で次材（前材に続いて圧延されるシートバー）をオシレーションさせながら待機させることもある。 However, in the actual rolling line, there is an uncertain factor that induces a decrease in the sheet bar surface temperature that is not reflected in the numerical calculation. For example, a shielding plate is used to prevent water scattering during the descaling process, but leaked water may be generated due to various circumstances. In such a case, the leaked water is seated in the front and rear areas of the descaling equipment. It stays on the upper surface of the bar and causes the surface temperature to decrease. Usually, the cooling device for the rolling roll is provided with a roll draining device so that the cooling water sprayed onto the rolling roll does not get on the surface of the sheet bar, but part of the cooling water may leak out. In addition, when the distance from the previous material (the previously rolled sheet bar) is narrowed, the next material (the sheet bar rolled following the previous material) is oscillated on the table in order to prevent collision between the sheet bars. Sometimes it is waiting.
図１２（ａ）は、一例として、可逆式圧延機３１による圧延に際してデスケーリング処理を行った際に、シートバー１０の上面に飛散水が滞留する様子を示した模式図であり、（ｂ）は、そのときのシートバー１０の表面温度を可逆式圧延機３１の上流側に設置した放射温度計３５で測定した結果を経過時間とともに示したグラフである。図中、（ｉ）はシートバー１０を上流側へ搬送し放射温度計３５に到達した時点を示し、（ｉｉ）は反転のためシートバー１０の搬送を一時的に停止した時点を示し、（ｉｉｉ）はシートバー１０を下流側へ搬送した後にその先端部がデスケーリング装置の、上流側のスプレーヘッダー３６に到達した時点を示し、（ｉｖ）はシートバー１０の尾端部が放射温度計３５から外れた時点を示している。なお、デスケーリング装置は、上下で対をなし、可逆式圧延機３１の前後にそれぞれ隣接配置された２対のスプレーヘッダー３６，３７からなり、各スプレーヘッダー３６，３７からはシートバー１０表層に生成されたスケールを除去するために高圧水が噴射される。前後のスプレーヘッダー３６，３７は、圧延方向に応じて交互に噴射を行う。また、高圧水の噴射は、シートバー１０が圧延機に噛み込まれる前に開始される。 FIG. 12A is a schematic diagram showing, as an example, a state in which scattered water stays on the upper surface of the sheet bar 10 when the descaling process is performed during rolling by the reversible rolling mill 31. These are the graphs which showed the result of having measured the surface temperature of the sheet bar 10 at that time with the radiation thermometer 35 installed in the upstream of the reversible rolling mill 31 with elapsed time. In the figure, (i) shows the time when the sheet bar 10 is conveyed upstream and reaches the radiation thermometer 35, (ii) shows the time when the conveyance of the sheet bar 10 is temporarily stopped due to inversion, iii) shows a point in time when the leading end of the sheet bar 10 reaches the upstream spray header 36 of the descaling apparatus after the sheet bar 10 is conveyed downstream, and (iv) shows the radiation thermometer at the tail end of the sheet bar 10. A time point deviating from 35 is shown. The descaling device is composed of two pairs of spray headers 36 and 37 that are paired up and down and arranged adjacent to each other before and after the reversible rolling mill 31, and from each spray header 36 and 37 to the surface layer of the seat bar 10 High pressure water is injected to remove the generated scale. The front and rear spray headers 36 and 37 alternately spray according to the rolling direction. Moreover, the injection of the high-pressure water is started before the sheet bar 10 is bitten by the rolling mill.
図１２（ｂ）のグラフによれば、圧延機３１を出た直後のシートバー１０の表面温度は、シートバー１０の先端が放射温度計３５を通過して３０〜４０秒後の温度より約１００℃低いことが分かる。また、リバース圧延を開始すると、デスケーリング装置のスプレーヘッダー３６，３７からの飛散水およびシートバー１０上面の乗り水の影響を受け、表面温度が約４２℃低下しており、不安定であることが分かる。このため、冷却装置により当初のセットアップ計算に基づく設定どおりに、シートバー１０の表面温度が相変態温度を下回らないように冷却を行っても、シートバー１０の表面温度が想定よりも低くなり、製造された熱延鋼帯の表層に相変態に起因する割れが発生する可能性がある。 According to the graph of FIG. 12 (b), the surface temperature of the sheet bar 10 immediately after leaving the rolling mill 31 is about 30 to 40 seconds after the tip of the sheet bar 10 passes through the radiation thermometer 35. It can be seen that it is 100 ° C lower. Further, when reverse rolling is started, the surface temperature is lowered by about 42 ° C. due to the influence of splash water from the spray headers 36 and 37 of the descaling device and the water on the upper surface of the seat bar 10 and is unstable. I understand. For this reason, even if cooling is performed so that the surface temperature of the seat bar 10 does not fall below the phase transformation temperature as set based on the initial setup calculation by the cooling device, the surface temperature of the seat bar 10 becomes lower than expected, Cracks due to phase transformation may occur on the surface layer of the manufactured hot rolled steel strip.
それ故本発明の課題は、制御圧延に先立って行う冷却中にシートバーの表層が相変態温度を下回ることを確実に防止しつつ、制御圧延開始までに要する時間を低減して能率よく熱延鋼帯を製造することができる熱延鋼帯の製造方法および熱延鋼帯の製造設備を提案することにある。 Therefore, the object of the present invention is to efficiently prevent hot rolling by reducing the time required to start controlled rolling while reliably preventing the surface layer of the sheet bar from falling below the phase transformation temperature during cooling prior to controlled rolling. The object is to propose a method of manufacturing a hot-rolled steel strip and a hot-rolled steel strip manufacturing facility capable of manufacturing a steel strip.
前記課題を有利に解決する本発明の熱延鋼帯の製造方法は、少なくとも１機の可逆式圧延機を含む複数の粗圧延機からなる粗圧延群と、前記可逆式圧延機の上流側または下流側に配置された冷却装置とを備え、前記冷却装置が、圧延方向で互いに隣り合って配置された、１０００Ｌ／ｍｉｎ・ｍ２未満の水量密度で被圧延材を緩冷却する緩冷却装置と１０００Ｌ／ｍｉｎ・ｍ２以上の水量密度で被圧延材を急冷却する急冷却装置とからなる、熱延鋼帯の製造設備を用い、被圧延材を前記可逆式圧延機の圧延パスの繰り返しに伴い、前記緩冷却装置により緩冷却した後に、板厚の減少に応じて前記急冷却装置により急冷却する、熱延鋼帯の製造方法であって、
被圧延材の表面温度を測定する温度計を、前記冷却装置からみて前記可逆式圧延機の反対側と、前記可逆式圧延機および前記冷却装置相互間と、前記可逆式圧延機からみて前記冷却装置の反対側とのうちの少なくとも１箇所に設置し、
前記温度計により前記冷却装置による冷却直前の被圧延材の表面温度を実測し、
前記温度計による測定で得られた被圧延材の実測表面温度に基づき、前記冷却装置に通過させる際の被圧延材の搬送速度と前記冷却装置における使用する噴射ヘッダー数とのうちの少なくとも一方を修正することを特徴とするものである。
The method for producing a hot-rolled steel strip of the present invention that advantageously solves the above problems includes a rough rolling group comprising a plurality of rough rolling mills including at least one reversible rolling mill, and an upstream side of the reversible rolling mill or A cooling device disposed on the downstream side, and the cooling device disposed adjacent to each other in the rolling direction, and a slow cooling device that slowly cools the material to be rolled at a water density of less than 1000 L / min · m 2 Using a hot-rolled steel strip manufacturing facility comprising a rapid cooling device that rapidly cools the material to be rolled at a water density of 1000 L / min · m 2 or more, the material to be rolled is repeated in the rolling pass of the reversible rolling mill. Along with the slow cooling by the slow cooling device, it is a method of manufacturing a hot-rolled steel strip that is rapidly cooled by the rapid cooling device according to a decrease in sheet thickness ,
A thermometer for measuring the surface temperature of the material to be rolled is the opposite side of the reversible rolling mill when viewed from the cooling device, the reversible rolling mill and the cooling device, and the cooling when viewed from the reversible rolling mill. Installed in at least one of the opposite sides of the device,
Measure the surface temperature of the material to be rolled immediately before cooling by the cooling device with the thermometer,
Based on the measured surface temperature of the material to be rolled obtained by measurement with the thermometer, at least one of the conveying speed of the material to be rolled when passing through the cooling device and the number of jet headers used in the cooling device is It is characterized by correction.
さらに、本発明の熱延鋼帯の製造方法においては、被圧延材の表面温度が、被圧延材の表層の相変態に関連した所定の基準温度以上に維持されるように、被圧延材の前記実測表面温度に基づき、前記冷却装置に通過させる際の被圧延材の搬送速度と前記冷却装置における使用する噴射ヘッダー数とのうちの少なくとも一方を修正する。 Furthermore, Oite method of manufacturing a hot rolled steel strip of the present invention, as the surface temperature of the rolled material is maintained at a predetermined reference temperature or more in relation to the phase transformation of the surface layer of the material to be rolled, the rolled Based on the measured surface temperature of the material, at least one of the conveyance speed of the material to be rolled when passing through the cooling device and the number of jet headers used in the cooling device is corrected .
なお、本発明の熱延鋼帯の製造方法にあっては、前記実測表面温度によりセットアップ計算を行い、該セットアップ計算の結果に基づき、前記冷却装置に通過させる際の被圧延材の搬送速度と前記冷却装置における使用する噴射ヘッダー数とのうちの少なくとも一方を修正することが好ましい。 In the method for manufacturing a hot-rolled steel strip according to the present invention, the setup calculation is performed based on the measured surface temperature, and based on the result of the setup calculation, the conveyance speed of the material to be rolled when passing through the cooling device and It is preferable to correct at least one of the number of jet headers used in the cooling device.
さらに、本発明の熱延鋼帯の製造方法にあっては、前記被圧延材の搬送速度の修正量が所定量以上の場合に、前記被圧延材の搬送速度の修正に加えて、前記使用する噴射ヘッダー数の修正を行うことが好ましい。 Furthermore, in the method for producing a hot-rolled steel strip according to the present invention, when the correction amount of the conveyance speed of the material to be rolled is a predetermined amount or more, in addition to the correction of the conveyance speed of the material to be rolled, the use It is preferable to correct the number of injection headers to be performed.
しかも、本発明の熱延鋼帯の製造方法にあっては、前記使用する噴射ヘッダー数の修正数がどの程度の前記搬送速度の修正量に相当するかの換算表をあらかじめ作成しておき、この換算表に基づき、前記搬送速度の修正量が前記所定量未満となるよう、使用する噴射ヘッダー数の修正数を決定することが好ましい。 Moreover, in the method for producing a hot-rolled steel strip according to the present invention, a conversion table indicating in advance how much the number of corrections of the number of jetting headers used corresponds to the amount of correction of the conveyance speed is prepared in advance. Based on this conversion table, it is preferable to determine the correction number of the number of injection headers to be used so that the correction amount of the transport speed is less than the predetermined amount.
また、前記課題を有利に解決する本発明の熱延鋼帯の製造設備は、少なくとも１機の可逆式圧延機を含む複数の粗圧延機からなる粗圧延群と、前記可逆式圧延機の上流側または下流側に配置された冷却装置と備え、前記冷却装置が、圧延方向で互いに隣り合って配置された１０００Ｌ／ｍｉｎ・ｍ２未満の水量密度で被圧延材を緩冷却する緩冷却装置と１０００Ｌ／ｍｉｎ・ｍ２以上の水量密度で被圧延材を急冷却する急冷却装置とからなり、被圧延材を前記可逆式圧延機の圧延パスの繰り返しに伴い、前記緩冷却装置により緩冷却した後に、板厚の減少に応じて前記急冷却装置により急冷却する、熱延鋼帯の製造設備であって、
前記冷却装置からみて前記可逆式圧延機の反対側と、前記可逆式圧延機および前記冷却装置相互間と、前記可逆式圧延機からみて前記冷却装置の反対側とのうちの少なくとも１箇所に設置された、被圧延材の表面温度を実測する温度計と、
前記温度計による測定で得られた被圧延材の実測表面温度に基づき、前記冷却装置に通過させる際の被圧延材の搬送速度と前記冷却装置における使用する噴射ヘッダー数とのうちの少なくとも一方を修正する修正手段と、を備えることを特徴とするものである。
The hot rolled steel strip manufacturing facility of the present invention that advantageously solves the above problems includes a rough rolling group comprising a plurality of rough rolling mills including at least one reversible rolling mill, and an upstream of the reversible rolling mill. A cooling device arranged on the side or downstream side, the cooling device arranged adjacent to each other in the rolling direction, and a slow cooling device that slowly cools the material to be rolled at a water density of less than 1000 L / min · m 2 1000L / min · m 2 or more of water density Ri Do and a rapid cooling apparatus for quenching the material to be rolled, with the material to be rolled to repeated rolling passes of the reversible rolling mill, slow cooling by the slow cooling device after, quenching by the quenching apparatus in accordance with the sheet thickness reduction, a manufacturing facility hot rolled strip,
Installed in at least one of the opposite side of the reversible rolling mill viewed from the cooling device, between the reversible rolling mill and the cooling device, and the opposite side of the cooling device viewed from the reversible rolling mill. A thermometer that actually measures the surface temperature of the material to be rolled,
Based on the measured surface temperature of the material to be rolled obtained by measurement with the thermometer, at least one of the conveying speed of the material to be rolled when passing through the cooling device and the number of jet headers used in the cooling device is And a correcting means for correcting.
さらに、本発明の熱延鋼帯の製造設備においては、前記修正手段は、被圧延材の表面温度が、被圧延材の相変態に関連した所定の基準温度以上に維持されるように、被圧延材の前記実測表面温度に基づき、前記冷却装置に通過させる際の被圧延材の搬送速度と前記冷却装置における使用する噴射ヘッダー数とのうちの少なくとも一方を修正する。 Furthermore, Oite the manufacturing facilities of hot rolled strip of the present invention, the correcting means, so that the surface temperature of the rolled material is maintained at a predetermined or reference temperature associated with the phase transformation of the material to be rolled Based on the measured surface temperature of the material to be rolled, at least one of the conveyance speed of the material to be rolled when passing through the cooling device and the number of jet headers used in the cooling device is corrected .
なお、本発明の熱延鋼帯の製造設備にあっては、前記修正手段は、前記実測表面温度によりセットアップ計算を行い、該セットアップ計算の結果に基づき、前記冷却装置に通過させる際の被圧延材の搬送速度と前記冷却装置における使用する噴射ヘッダー数とのうちの少なくとも一方を修正することが好ましい。 In the production facility for hot-rolled steel strip of the present invention, the correction means performs a setup calculation based on the measured surface temperature, and is rolled when passing through the cooling device based on the result of the setup calculation. It is preferable to correct at least one of the conveying speed of the material and the number of jet headers used in the cooling device.
さらに、本発明の熱延鋼帯の製造設備にあっては、前記修正手段は、前記被圧延材の搬送速度の修正量が所定量以上の場合に、前記被圧延材の搬送速度の修正に加えて、前記使用する噴射ヘッダー数の修正を行うことが好ましい。 Further, in the hot-rolled steel strip manufacturing facility of the present invention, the correction means corrects the conveyance speed of the material to be rolled when the correction amount of the conveyance speed of the material to be rolled is a predetermined amount or more. In addition, it is preferable to correct the number of injection headers used.
しかも、本発明の熱延鋼帯の製造設備にあっては、前記修正手段は、あらかじめ作成された、前記使用する噴射ヘッダー数の修正数がどの程度の前記搬送速度の修正量に相当するかの換算表に基づき、前記搬送速度の修正量が前記所定量未満となるよう、使用する噴射ヘッダー数の修正数を決定することが好ましい。 Moreover, in the production facility for hot-rolled steel strip according to the present invention, the correction means corresponds to the correction amount of the conveyance speed to which the correction number of the injection header number to be used is prepared in advance. Based on the conversion table, it is preferable to determine the correction number of the number of injection headers to be used so that the correction amount of the transport speed is less than the predetermined amount.
本発明の熱延鋼帯の製造方法および熱延鋼帯の製造設備によれば、被圧延材が冷却装置に進入する前に、被圧延材の表面温度を実測し、その測定結果（実測表面温度）に基づき冷却装置に通過させる被圧延材の搬送速度と冷却装置における使用する噴射ヘッダー数とのうちの少なくとも一方を修正するようにしたので、例えば冷却装置に進入する被圧延材の表面温度が想定よりも低い場合には、被圧延材の搬送速度を増大させたり使用する噴射ヘッダー数を減少させたりすることで冷却速度を緩やかにして冷却中に被圧延材の表面温度が相変態温度を下回ることを確実に防止することができる。 According to the method for producing a hot-rolled steel strip and the equipment for producing a hot-rolled steel strip according to the present invention, the surface temperature of the material to be rolled is measured before the material to be rolled enters the cooling device, and the measurement result (measured surface) Temperature), at least one of the transport speed of the material to be passed to the cooling device and the number of jet headers used in the cooling device is corrected. For example, the surface temperature of the material to be rolled entering the cooling device If the temperature is lower than expected, the surface temperature of the material to be rolled is changed to the phase transformation temperature during cooling by increasing the conveying speed of the material to be rolled or decreasing the number of jet headers to be used to reduce the cooling rate. Can be reliably prevented from falling below.
以下、一般的な熱延鋼帯の製造方法および製造設備を説明した後、この発明の実施の形態を図面に基づき詳細に説明する。図１１は、一般的な熱延鋼帯の製造設備を圧延パスとともに模式的に示す構成図である。 Hereinafter, after explaining a manufacturing method and manufacturing equipment of a general hot-rolled steel strip, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 11 is a configuration diagram schematically showing a general hot-rolled steel strip manufacturing facility together with a rolling pass.
まず、一般的な熱延鋼帯の製造では、図１１に示すように、連続加熱炉1で例えば板厚み２６０ｍｍの被圧延材（スラブ）を１２５０℃に加熱し、その後、粗圧延機群３により所定の厚みのシート状の被圧延材であるシートバー１０とする。この際に、シートバー１０の板幅を調整するために、連続加熱炉１の出側に設置されているサイジングプレス２で、所定のサイズまで幅方向に圧下した後に、粗圧延機群３の圧延機に近接した位置に設置されているエッジャー４で同じく幅方向に圧下する。次いで、クロップシャー５によりシートバー１０の先端および尾端を切断した後に、そのシートバー１０を仕上げ圧延機群６で所定の厚み(例えば２０ｍｍ)まで仕上げ圧延して熱延鋼帯とし、その後、ランアウトテーブル７にて所定の温度まで冷却した後に、コイラー８で巻き取る。 First, in the production of a general hot-rolled steel strip, as shown in FIG. 11, a material to be rolled (slab) having a thickness of, for example, 260 mm is heated to 1250 ° C. in a continuous heating furnace 1, and then the rough rolling mill group 3 The sheet bar 10 is a sheet-like material to be rolled having a predetermined thickness. At this time, in order to adjust the sheet width of the sheet bar 10, the sizing press 2 installed on the exit side of the continuous heating furnace 1 is crushed down to a predetermined size in the width direction, The edger 4 installed at a position close to the rolling mill is similarly rolled down in the width direction. Next, after cutting the leading end and tail end of the sheet bar 10 by the crop shear 5, the sheet bar 10 is finish-rolled to a predetermined thickness (for example, 20 mm) with a finish rolling mill group 6 to form a hot-rolled steel strip, After being cooled to a predetermined temperature by the runout table 7, it is wound up by a coiler 8.
図示例では粗圧延機群３は２機の粗圧延機から構成されており、粗圧延機群３のうち上流側(加熱炉側)には、リバース圧延可能な可逆式圧延機３１、下流側には下流側への搬送方向のみの圧延が可能な非可逆式圧延機３２が配置されている。この粗圧延機群３により、例えば、可逆式圧延機３１で５〜１１パス程度圧延した後に、非可逆式圧延機３２で１パスのみ圧延をする。 In the illustrated example, the rough rolling mill group 3 is composed of two rough rolling mills. The upstream side (heating furnace side) of the rough rolling mill group 3 is a reversible rolling mill 31 capable of reverse rolling, and the downstream side. Is provided with a nonreciprocal rolling mill 32 capable of rolling only in the conveying direction to the downstream side. With this rough rolling mill group 3, for example, after rolling about 5 to 11 passes with the reversible rolling mill 31, only one pass is rolled with the irreversible rolling mill 32.
従来、所定の制御圧延開始厚みまで圧延されたシートバー１０は、所定の制御圧延開始温度に下がるまで粗圧延機群３と仕上げ圧延機群６の間でオシレーション待機される。シートバー１０の表面温度は放射温度計３３で測定し、シートバー１０の表面温度が所定の制御圧延開始温度にまで下がったことを確認した後、仕上げ圧延機群６に送り制御圧延を実施する。この際、空冷により１５０〜２５０℃程度温度を低下させるため、６０〜３００秒程度待機させる必要がある。この間、仕上げ圧延機群６では圧延を行うことができないため圧延能率の低下につながる。また、このときのシートバー１０の厚みを例えば５０ｍｍとすると、シートバー１０の長さは５０ｍ程度と極めて長いため、上記先行文献３や４に開示されるような、シートバーを持ち上げる昇降装置等の機構を導入するのは現実的ではない。 Conventionally, the sheet bar 10 rolled to a predetermined controlled rolling start thickness is subjected to oscillation waiting between the rough rolling mill group 3 and the finish rolling mill group 6 until it falls to a predetermined controlled rolling start temperature. The surface temperature of the sheet bar 10 is measured with a radiation thermometer 33, and after confirming that the surface temperature of the sheet bar 10 has been lowered to a predetermined controlled rolling start temperature, it is fed to the finish rolling mill group 6 to perform controlled rolling. . At this time, since the temperature is lowered by about 150 to 250 ° C. by air cooling, it is necessary to wait for about 60 to 300 seconds. During this time, the finish rolling mill group 6 cannot perform rolling, leading to a reduction in rolling efficiency. Further, if the thickness of the seat bar 10 at this time is 50 mm, for example, the length of the seat bar 10 is as long as about 50 m. Therefore, as disclosed in the prior art documents 3 and 4, the lifting device for lifting the seat bar, etc. It is not realistic to introduce this mechanism.
そこで、本発明の実施形態では、図１に示すように、粗圧延機群３の可逆式圧延機３１の上流側または下流側（図示例では下流側）に、水量密度１０００Ｌ／ｍｉｎ・ｍ２以上でシートバー１０を冷却する急冷却装置４１と水量密度１０００Ｌ／ｍｉｎ・ｍ２未満でシートバー１０を冷却する緩冷却装置４２とを有する冷却装置４３を設けて、粗圧延機群３内で圧延に加えて冷却を実施する構成を採用している。これにより、粗圧延機群３での圧延が完了した時点でシートバー１０の温度を制御圧延開始温度と等しくなるように調整することができ、制御圧延温度待ち時間を大幅に短縮することができる。 Therefore, in the embodiment of the present invention, as shown in FIG. 1, the water density is 1000 L / min · m 2 on the upstream side or the downstream side (downstream side in the illustrated example) of the reversible rolling mill 31 of the rough rolling mill group 3. In the rough rolling mill group 3, a cooling device 43 having the rapid cooling device 41 for cooling the sheet bar 10 and the slow cooling device 42 for cooling the sheet bar 10 with a water density of less than 1000 L / min · m 2 is provided. The structure which cools in addition to rolling is adopted. Thereby, when rolling in the rough rolling mill group 3 is completed, the temperature of the sheet bar 10 can be adjusted to be equal to the control rolling start temperature, and the control rolling temperature waiting time can be greatly shortened. .
急冷却装置４１および緩冷却装置４２は圧延方向で互いに隣り合って配置される。「隣り合って配置される」とは、急冷却装置４１と緩冷却装置４２とがその相互間に粗圧延機を介さず圧延方向に直接隣り合って配置されることを意味する。 The rapid cooling device 41 and the slow cooling device 42 are arranged next to each other in the rolling direction. “Arranged next to each other” means that the rapid cooling device 41 and the slow cooling device 42 are directly adjacent to each other in the rolling direction without using a rough rolling mill therebetween.
急冷却装置４１および緩冷却装置４２によるシートバー１０の冷却順序としては、まず緩冷却装置４２によりシートバー１０を緩冷却し、該緩冷却が完了した後に急冷却装置４１によりシートバー１０を急冷却することが肝要である。具体的には、可逆式圧延機３１で繰り返し圧延されていくシートバー１０の厚みに応じて急冷却装置４１と緩冷却装置４２を使い分ける。つまりシートバー１０の厚みが比較的厚い圧延初期では、可逆式圧延機３１の圧延パスに関連して、緩冷却装置４２による緩冷却を行い、シートバー１０の厚みが比較的薄い圧延後期では、可逆式圧延機３１の圧延パスに関連して、急冷却装置４１による急冷却を行う。このような冷却を行う理由は次の通りである。 The cooling order of the seat bar 10 by the rapid cooling device 41 and the slow cooling device 42 is as follows. First, the slow cooling device 42 gently cools the seat bar 10, and after the slow cooling is completed, the rapid cooling device 41 suddenly cools the seat bar 10. Cooling is essential. Specifically, the rapid cooling device 41 and the slow cooling device 42 are selectively used according to the thickness of the sheet bar 10 that is repeatedly rolled by the reversible rolling mill 31. That is, in the early rolling stage where the thickness of the sheet bar 10 is relatively thick, the slow cooling by the slow cooling device 42 is performed in relation to the rolling pass of the reversible rolling mill 31, and in the late rolling stage where the thickness of the sheet bar 10 is relatively small, In association with the rolling pass of the reversible rolling mill 31, rapid cooling by the rapid cooling device 41 is performed. The reason for performing such cooling is as follows.
図２に一例として板厚み４０ｍｍのシートバー１０を様々な冷却水量密度で冷却したときの表面の温度履歴を示す。図中、急激に温度が低下している時間領域は水冷を実施したことを示しており、下限温度を経て温度が上昇している時間領域は水冷を停止し放冷（空冷）を実施したことを示している。この図から冷却水の水量密度が多くなるに連れて表面の冷却速度(温度の時間勾配)は早くなることが分かる。一方、シートバー１０の温度が相変態に関連した所定の基準温度（以下、相変態温度と称す）である６００℃を下回ると、相変態が起こりオーステナイト組織からフェライト組織に変化する。このような状態で制御圧延を行った場合、表面延性が低下しフェライト粒界からの割れが発生するリスクがある。そのため、水冷中のシートバー１０の最表層の温度は６００℃以上に保持することが好ましい。図２に示す例ではそのような観点から、シートバー１０の表面温度が下限温度の６００℃となったところで水冷を停止している。図３は、そのときのシートバー１０の断面平均温度を示す。同じく図中の急激に温度が低下している時間領域は水冷を実施したことを示す。冷却水の水量密度が高いとシートバー１０の断面平均温度の時間勾配、つまり冷却速度は急峻になるものの、表面温度を６００℃以上に保持しフェライト粒界からの割れを防止する観点から冷却水の供給を途中で停止しているため、冷却水の水量密度が高いほど冷却終了時の温度も高くなる。そのため、冷却水の水量密度を小さくするほど、冷却速度は遅いものの、１回で冷却可能な温度降下量を大きくすることができることが分かる。 As an example, FIG. 2 shows the temperature history of the surface when the sheet bar 10 having a plate thickness of 40 mm is cooled at various cooling water density. In the figure, the time region in which the temperature suddenly decreases indicates that water cooling has been performed, and the time region in which the temperature has increased through the lower limit temperature has been stopped and allowed to cool (air cooling). Is shown. From this figure, it can be seen that the cooling rate of the surface (temperature temperature gradient) increases as the water density of the cooling water increases. On the other hand, when the temperature of the sheet bar 10 falls below 600 ° C., which is a predetermined reference temperature related to phase transformation (hereinafter referred to as phase transformation temperature), phase transformation occurs and changes from an austenite structure to a ferrite structure. When controlled rolling is performed in such a state, there is a risk that surface ductility is reduced and cracks from ferrite grain boundaries occur. Therefore, the temperature of the outermost layer of the sheet bar 10 during water cooling is preferably maintained at 600 ° C. or higher. In the example shown in FIG. 2, from such a viewpoint, the water cooling is stopped when the surface temperature of the seat bar 10 reaches the lower limit temperature of 600 ° C. FIG. 3 shows the average cross-sectional temperature of the sheet bar 10 at that time. Similarly, the time region where the temperature rapidly decreases in the figure indicates that water cooling was performed. When the cooling water quantity density is high, the time gradient of the cross-sectional average temperature of the sheet bar 10, that is, the cooling rate becomes steep, but the cooling water is used from the viewpoint of maintaining the surface temperature at 600 ° C. or higher and preventing cracks from ferrite grain boundaries. Therefore, the higher the cooling water quantity density, the higher the temperature at the end of cooling. Therefore, it can be seen that the smaller the cooling water density, the slower the cooling rate, but the larger the temperature drop that can be cooled at one time.
図４には初期の表面温度が１０００℃の様々な板厚のシートバー１０について、冷却水量密度と表面温度が６００℃となるまで冷却をしたときの断面平均の温度降下量との関係を示す。先に説明したように、表面温度を６００℃以上に保持するという制約条件があることで、板厚みが大きくなるほど、また冷却水の水量密度が大きくなるほど１回の水冷による冷却温度降下量は小さくなる。以後、表面温度６００℃の制約から1回の冷却で降下させることができる温度を限界温度降下量と呼ぶ。 FIG. 4 shows the relationship between the cooling water density and the average temperature drop of the cross-section when cooling is performed until the surface temperature reaches 600 ° C. for sheet bars 10 having various plate thicknesses with an initial surface temperature of 1000 ° C. . As described above, there is a constraint condition that the surface temperature is kept at 600 ° C. or higher, so that the cooling temperature drop by one water cooling decreases as the plate thickness increases and the cooling water density increases. Become. Hereinafter, the temperature that can be lowered by one cooling due to the restriction of the surface temperature of 600 ° C. is referred to as a critical temperature drop amount.
図５には初期の表面温度が１０００℃の様々な板厚のシートバー１０について、冷却水の水量密度とシートバー１０の冷却速度の断面平均との関係を示す。冷却水の水量密度が大きいほど冷却速度は速い。そのため、先の制約を併せて考えると、限界温度降下量以下の冷却を実施する場合は、冷却水の水量密度を高くするほうが短い時間で温度を降下させることが出来るため、圧延時間の短縮には有利となる。 FIG. 5 shows the relationship between the water density of the cooling water and the cross-sectional average of the cooling rate of the sheet bar 10 for sheet bars 10 having various plate thicknesses with an initial surface temperature of 1000 ° C. The cooling rate is faster as the water density of the cooling water is larger. For this reason, considering the above constraints, when cooling below the limit temperature drop, the temperature can be lowered in a shorter time by increasing the water density of the cooling water. Is advantageous.
ここで実際の圧延工程を考えると、２２０〜２６０ｍｍ程度の厚みを持つスラブを４５ｍｍ程度まで１０パス前後で圧延する。圧延初期では板厚みが大きく限界温度降下量が小さくなる傾向にあるため、１パスあたりの表面の下限温度の点から限界温度降下量が大きい緩冷却が有利である。圧延後期の板厚みが小さくなった条件では、限界温度降下量を大きくとることができるので、冷却速度を高めて短い時間で水冷する急冷却のほうが有利になる。また、板厚みが小さいほうが限界温度降下量が大きいことから、複数の粗圧延機が設けられている場合は、最も小さい板厚みに対応した最下流の可逆式圧延機３１の上流側若しくは下流側において冷却を実施するのが好適である。 Here, considering an actual rolling process, a slab having a thickness of about 220 to 260 mm is rolled to about 45 mm in about 10 passes. Since the sheet thickness tends to be large and the critical temperature drop amount tends to be small at the beginning of rolling, slow cooling with a large critical temperature drop amount is advantageous in terms of the lower limit temperature of the surface per pass. Under the condition that the plate thickness is reduced in the later stage of rolling, the amount of critical temperature drop can be increased. Therefore, rapid cooling in which water is cooled in a short time by increasing the cooling rate is more advantageous. Moreover, since the limit temperature drop amount is larger when the plate thickness is smaller, when a plurality of rough rolling mills are provided, the upstream side or the downstream side of the most downstream reversible rolling mill 31 corresponding to the smallest plate thickness. It is preferred to carry out the cooling in
また、図４から分かるように、板厚みが比較的大きい８０ｍｍおよび１２０ｍｍの場合では、冷却水の水量密度が１０００Ｌ／ｍｉｎ・ｍ２を境に、低水量密度では限界温度降下量が大きくなる。そのため、シートバー１０の表面のフェライト割れを防止する観点から、板厚み８０ｍｍ以上では冷却水の水量密度を１０００Ｌ／ｍｉｎ・ｍ２未満とすることで大きな限界温度降下量を確保することができる。 In addition, as can be seen from FIG. 4, in the case of 80 mm and 120 mm where the plate thickness is relatively large, the critical temperature drop amount becomes large at a low water amount density, with the water amount density of the cooling water being 1000 L / min · m 2 as a boundary. Therefore, from the viewpoint of preventing ferrite cracks on the surface of the sheet bar 10, when the plate thickness is 80 mm or more, a large limit temperature drop can be ensured by setting the water density of the cooling water to less than 1000 L / min · m 2 .
このような理由から、本発明の実施形態では制御圧延に望ましい所定温度（制御圧延開始温度）までの冷却を複数パスに分散させ、１パスで２０〜３０℃程度の冷却を実施し、その際、板厚みが比較的大きい、特に板厚みが８０ｍｍ以上である圧延初期には、水量密度が１０００Ｌ／ｍｉｎ・ｍ２未満である緩冷却装置４２で緩冷却を実施し、板厚みが比較的小さい、特に板厚みが８０ｍｍ未満となる圧延後期には、水量密度が１０００Ｌ／ｍｉｎ・ｍ２以上の急冷却装置４１で急冷却を実施する構成とている。 For these reasons, in the embodiment of the present invention, cooling to a predetermined temperature (controlled rolling start temperature) desirable for controlled rolling is dispersed in a plurality of passes, and cooling is performed at about 20 to 30 ° C. in one pass. In the initial rolling stage where the plate thickness is relatively large, particularly the plate thickness is 80 mm or more, slow cooling is performed by the slow cooling device 42 having a water density of less than 1000 L / min · m 2 , and the plate thickness is relatively small. In particular, in the latter stage of rolling when the plate thickness is less than 80 mm, rapid cooling is performed by the rapid cooling device 41 having a water density of 1000 L / min · m 2 or more.
なお、緩冷却装置４２では、冷却水の水量密度を下げるほど１パスあたりの水冷による温度降下量は大きくなるが、冷却速度は遅くなるため、能率を向上させる効果が小さくなる。そこで、緩冷却装置４２の冷却水量は２００Ｌ／ｍｉｎ・ｍ２以上とするのが好ましい。一方、急冷却装置４１では、冷却水量密度を大きくするほど1パスあたりの水冷による温度降下量は小さくなるが、冷却速度は速くなる。そのため、1パスあたりの限界冷却能力があまり変わらない範囲では、冷却水量増大に伴う設備コストの上昇もあるため、冷却水の水量密度を６０００Ｌ／ｍｉｎ・ｍ２以下とするのが好ましい。 In the slow cooling device 42, the temperature drop amount due to water cooling per pass increases as the cooling water amount density decreases, but the cooling rate decreases, and the effect of improving the efficiency decreases. Therefore, the amount of cooling water in the slow cooling device 42 is preferably 200 L / min · m 2 or more. On the other hand, in the rapid cooling device 41, the amount of temperature drop due to water cooling per pass is reduced as the cooling water density is increased, but the cooling rate is increased. Therefore, in the range where the limit cooling capacity per pass does not change so much, the equipment cost increases with the increase in the amount of cooling water. Therefore, the water density of the cooling water is preferably 6000 L / min · m 2 or less.
各冷却装置４１，４２は、複数の円管ノズルから構成される群噴流冷却、パイプラミナー、ミスト冷却、スプレー冷却などいかなる形式のものでもかまわないが、急冷却装置４１では冷却水量が多いためシートバー１０上に厚い滞留水が発生し易く、当該滞留水が噴射された冷却水の、鋼板表面への衝突を阻害する結果、安定した冷却が得られない可能性がある。そこで、急冷却装置４１には、液膜に対する貫通力の高い、円管ノズルを複数有する群噴流冷却装置を用いることが好ましい。一方、緩冷却装置４２では特に制限はなく、一般的に熱延鋼帯の冷却装置で使われているパイプラミナー方式やスプレー方式を用いることができる。 The cooling devices 41 and 42 may be of any type such as group jet cooling composed of a plurality of circular tube nozzles, pipe laminar, mist cooling, spray cooling, etc. However, since the rapid cooling device 41 has a large amount of cooling water, it is a sheet. As a result, thick stagnant water is likely to be generated on the bar 10, and the cooling water into which the stagnant water is jetted may interfere with the collision with the steel plate surface. As a result, stable cooling may not be obtained. Therefore, it is preferable to use a group jet cooling device having a plurality of circular tube nozzles having a high penetrating force for the liquid film as the rapid cooling device 41. On the other hand, the slow cooling device 42 is not particularly limited, and a pipe laminar method or a spray method generally used in a cooling device for a hot-rolled steel strip can be used.
急冷却装置４１および緩冷却装置４２は、圧延方向でみて可逆式圧延機３１に対して近い位置に急冷却装置４１、遠い位置に緩冷却装置４２の順に配置するのが好ましい。本実施形態では、シートバー１０の厚みに応じて急冷却装置４１と緩冷却装置４２を使い分けると説明したが、シートバー１０は各圧延パスで圧下されることで板厚みが順次小さくなり、その分だけシートバー１０の長さは順次長くなる。つまり急冷却装置４１を使用する圧延後期では、シートバー１の長さは最も大きくなる。一般的な粗圧延機群のレイアウトは、設計仕様のパススケジュールに基づき、各粗圧延機の間隔が決まっている。そのため、シートバー１０を急冷却装置４１および緩冷却装置４２で通過冷却する際に、シートバー１０が長いとシートバー１０が急冷却装置４１および緩冷却装置４２から出た時点で隣接する粗圧延機まで到達して干渉する恐れがある。そこで、板厚みが小さく長いシートバー１０に対して冷却を行う急冷却装置４１は、可逆式圧延機３１に近い位置に設置するのが好ましい。 The rapid cooling device 41 and the slow cooling device 42 are preferably arranged in the order of the rapid cooling device 41 at a position close to the reversible rolling mill 31 in the rolling direction and the slow cooling device 42 at a far position. In the present embodiment, it has been described that the rapid cooling device 41 and the slow cooling device 42 are selectively used according to the thickness of the sheet bar 10, but the sheet bar 10 is successively reduced in each rolling pass, and the plate thickness is sequentially reduced. The length of the sheet bar 10 is gradually increased by that amount. That is, the length of the sheet bar 1 is the largest in the late rolling stage in which the rapid cooling device 41 is used. In the layout of a general rough rolling mill group, the interval between the rough rolling mills is determined based on the pass schedule of the design specification. Therefore, when the sheet bar 10 is passed and cooled by the rapid cooling device 41 and the slow cooling device 42, if the sheet bar 10 is long, the rough rolling adjacent to the sheet bar 10 when it leaves the rapid cooling device 41 and the slow cooling device 42. There is a risk of reaching the aircraft and interfering. Therefore, the rapid cooling device 41 that cools the sheet bar 10 with a small plate thickness is preferably installed at a position close to the reversible rolling mill 31.
このように、可逆式圧延機３１の上流側または下流側において、まず緩冷却装置４２により１０００Ｌ／ｍｉｎ・ｍ２未満の水量密度でシートバー１０を緩冷却し、その後、シートバー１０を急冷却装置により１０００Ｌ／ｍｉｎ・ｍ２以上の水量密度で急冷却することで、シートバー１０の表層の温度が相変態温度を下回るのを防止しつつ、冷却に要する時間を短縮することができ、圧延能率を向上させることができる。 Thus, on the upstream side or the downstream side of the reversible rolling mill 31, the sheet bar 10 is first slowly cooled by the slow cooling device 42 with a water density of less than 1000 L / min · m 2 , and then the sheet bar 10 is rapidly cooled. By rapidly cooling with a water density of 1000 L / min · m 2 or more by the apparatus, the time required for cooling can be shortened while preventing the temperature of the surface layer of the sheet bar 10 from falling below the phase transformation temperature. Efficiency can be improved.
ところで、実際の圧延工程では、図１２を参照して説明したように、設備状況の変化やテーブル上での偶発的な材料待ち等に起因して、粗圧延開始前または粗圧延工程中にシートバー１０の温度が想定外に低下する場合がある。この場合、冷却装置４３により当初のセットアップ計算に基づく設定どおりに冷却を行うと、シートバー１０の表面温度が想定していた温度よりも低くなり、その結果シートバー１０の表層が相変態温度を下回る可能性がある。 By the way, in the actual rolling process, as described with reference to FIG. 12, the sheet before the start of the rough rolling or during the rough rolling process due to a change in the equipment status or an accidental waiting of the material on the table. The temperature of the bar 10 may decrease unexpectedly. In this case, when the cooling device 43 performs cooling as set based on the initial setup calculation, the surface temperature of the seat bar 10 becomes lower than the assumed temperature, and as a result, the surface layer of the seat bar 10 has the phase transformation temperature. It may be lower.
そこで本実施形態では、図１に示すように、シートバー１０の表面温度を測定する温度計４５，４６を、冷却装置４３からみて可逆式圧延機３１の反対側（可逆式圧延機３１の上流側）と、可逆式圧延機３１からみて冷却装置４３の反対側（冷却装置４３の下流側）の２箇所に設置する。温度計４５，４６としては、測定対象表面の放射エネルギを検知する放射温度計を用いることが好ましい。図１（ａ）に示すように、可逆式圧延機３１と冷却装置４３との距離が、冷却を行う時点でのシートバー１０の長さよりも小さい場合は、可逆式圧延機３１で圧延しながら水冷を実施することになる。このような場合には、可逆式圧延機３１の上流側に設置されている温度計４５でシートバー１０の表面を測定（実測）する。「実測」とは、実際のシートバー１０から得られる情報に基づいてシートバー１０の表面温度を求めることを指す。そして、温度計４５による測定で得られたシートバー１０の表面温度（以下、実測表面温度と称す）が、セットアップ計算であらかじめ算出（予測）した同一時点、同一位置における表面温度（以下、計算表面温度と称す）よりも低い場合、実測表面温度を起点として、冷却後のシートバー１０の表面温度が相変態温度以上となるよう、再度セットアップ計算を行い、該セットアップ計算の結果に基づき、冷却装置４３に通過させるシートバー１０の搬送速度と冷却装置４３における使用する噴射ヘッダー数とのうちの少なくとも一方を修正する。 Therefore, in the present embodiment, as shown in FIG. 1, the thermometers 45 and 46 that measure the surface temperature of the sheet bar 10 are opposite to the reversible rolling mill 31 as viewed from the cooling device 43 (upstream of the reversible rolling mill 31. Side) and the opposite side of the cooling device 43 as viewed from the reversible rolling mill 31 (downstream side of the cooling device 43). As the thermometers 45 and 46, it is preferable to use a radiation thermometer that detects the radiation energy of the surface to be measured. As shown in FIG. 1 (a), when the distance between the reversible rolling mill 31 and the cooling device 43 is smaller than the length of the sheet bar 10 at the time of cooling, while rolling with the reversible rolling mill 31 Water cooling will be carried out. In such a case, the surface of the sheet bar 10 is measured (actually measured) with the thermometer 45 installed on the upstream side of the reversible rolling mill 31. “Actual measurement” refers to obtaining the surface temperature of the sheet bar 10 based on information obtained from the actual sheet bar 10. The surface temperature of the sheet bar 10 obtained by measurement with the thermometer 45 (hereinafter referred to as measured surface temperature) is the surface temperature (hereinafter referred to as calculated surface) at the same time and position calculated in advance (predicted) by the setup calculation. If the temperature is lower than the measured temperature, the setup calculation is performed again so that the surface temperature of the sheet bar 10 after cooling becomes equal to or higher than the phase transformation temperature, based on the result of the setup calculation. At least one of the conveying speed of the sheet bar 10 passed through 43 and the number of jet headers used in the cooling device 43 is corrected.
冷却装置４３に通過させて冷却したシートバー１０をリバース搬送し、再び冷却装置４３で冷却する場合は、図１（ｂ）に示すように、冷却直前のシートバー１０の表面温度は可逆式圧延機３１からみて冷却装置４３の反対側（冷却装置４３の下流側）に設置された温度計４６で測定する。シートバー１０の実測表面温度が、セットアップ計算であらかじめ算出した同一時点、同一位置における計算表面温度よりも低い場合、実測表面温度を起点として、冷却後のシートバー１０が相変態温度以上となるよう再度セットアップ計算を行い、該セットアップ計算の結果に基づき、冷却装置４３に通過させるシートバー１０の搬送速度と冷却装置４３における使用する噴射ヘッダー数とのうちの少なくとも一方を修正する。 When the sheet bar 10 cooled by passing through the cooling device 43 is reverse-conveyed and cooled again by the cooling device 43, the surface temperature of the sheet bar 10 just before cooling is reversible rolling as shown in FIG. The temperature is measured by a thermometer 46 installed on the opposite side of the cooling device 43 (downstream side of the cooling device 43) as viewed from the machine 31. When the measured surface temperature of the seat bar 10 is lower than the calculated surface temperature at the same time and the same position calculated in advance by the setup calculation, the seat bar 10 after cooling is set to be equal to or higher than the phase transformation temperature starting from the measured surface temperature. The setup calculation is performed again, and at least one of the conveying speed of the sheet bar 10 passed through the cooling device 43 and the number of jet headers used in the cooling device 43 is corrected based on the result of the setup calculation.
冷却装置４３に通過させるシートバー１０の搬送速度を変更すると冷却装置４３で冷却される冷却時間を調整できる。また、冷却装置４３の急冷却装置４１および緩冷却装置４２はそれぞれ、所定ピッチで配列された複数の噴射ヘッダーを有しており、一部の噴射ヘッダーのバルブを閉止して使用する噴射ヘッダー数を減らすことにより冷却長を短くし、冷却時間を短くすることができる。例えば、冷却時間を当初予定されていた冷却時間の７５％にまで減少させるためには、噴射ヘッダー数を２５％減らすか、搬送速度を１．３３（＝１／０．７５）倍に増大させればよい。 When the conveying speed of the sheet bar 10 passed through the cooling device 43 is changed, the cooling time cooled by the cooling device 43 can be adjusted. The rapid cooling device 41 and the slow cooling device 42 of the cooling device 43 each have a plurality of injection headers arranged at a predetermined pitch, and the number of injection headers to be used with some of the injection header valves closed. By reducing, the cooling length can be shortened and the cooling time can be shortened. For example, in order to reduce the cooling time to 75% of the originally planned cooling time, the number of jet headers is reduced by 25% or the conveyance speed is increased by 1.33 (= 1 / 0.75) times. Just do it.
図６に示すように、可逆式圧延機３１と冷却装置４３との間に温度計４７を配置してもよい。図６（ａ）に示すように、可逆式圧延機３１と冷却装置４３との距離が、水冷時の厚みにおけるシートバー１０の長さよりも大きい場合、可逆式圧延機３１でシートバー１０を圧下した後でかつ冷却装置４３への進入前に温度計４７によりシートバー１０の表面温度を測定し、必要に応じてシートバー１０の搬送速度と使用する噴射ヘッダー数とのうちの少なくとも一方を修正した後に冷却装置４３を通過させることで、冷却時の温度降下量を自在に調整することができる。図６（ｂ）は、リバース搬送時の様子を示しており、この場合は、冷却装置４３の下流側に設置された温度計４６により、冷却装置４３への進入前にシートバー１０の表面温度を測定し、必要に応じてシートバー１０の搬送速度と使用する噴射ヘッダー数とのうちの少なくとも一方を修正してから冷却装置４３に通過させる。 As shown in FIG. 6, a thermometer 47 may be disposed between the reversible rolling mill 31 and the cooling device 43. As shown in FIG. 6A, when the distance between the reversible rolling mill 31 and the cooling device 43 is larger than the length of the sheet bar 10 in the thickness at the time of water cooling, the sheet bar 10 is reduced by the reversible rolling mill 31. After that, and before entering the cooling device 43, the surface temperature of the sheet bar 10 is measured by the thermometer 47, and at least one of the conveying speed of the sheet bar 10 and the number of jet headers to be used is corrected as necessary. Then, by passing the cooling device 43, the amount of temperature drop during cooling can be freely adjusted. FIG. 6B shows a state during reverse conveyance. In this case, the surface temperature of the seat bar 10 before entering the cooling device 43 is measured by a thermometer 46 installed on the downstream side of the cooling device 43. , And if necessary, correct at least one of the conveying speed of the sheet bar 10 and the number of jet headers to be used, and then pass it through the cooling device 43.
シートバー１０の実測表面温度を起点として再度セットアップ計算を行い、該セットアップ計算の結果に基づき、冷却装置４３に通過させるシートバー１０の搬送速度と冷却装置４３における使用する噴射ヘッダー数とのうちの少なくとも一方を修正するためには、数値演算機能を有する図示しない既存のプロセスコンピュータを利用することができ、このプロセスコンピュータが本発明における修正手段を構成する。 The setup calculation is performed again with the measured surface temperature of the seat bar 10 as a starting point, and based on the result of the setup calculation, of the conveying speed of the sheet bar 10 passed through the cooling device 43 and the number of jet headers used in the cooling device 43 In order to correct at least one of them, an existing process computer (not shown) having a numerical operation function can be used, and this process computer constitutes the correcting means in the present invention.
図７に、冷却装置４３に通過させるシートバー１０の搬送速度を修正しない場合と修正する場合のシミュレーション例を示す。ここで図７（ａ）は、冷却対象であるシートバー１０の板厚が８０ｍｍ、該シートバー１０の表面温度および断面平均温度が共に８００℃、緩冷却装置４２の水量密度が５００Ｌ／ｍｉｎ・ｍ２という初期条件で、セットアップ計算によりシートバー１０の表面温度が６００℃となるまで冷却するよう搬送速度を決定したときのシートバー１０の温度経過のシミュレーション結果を示している。図７（ｂ）は、シートバー１０の断面平均温度が８００℃で図７（ａ）と同条件であるが、上述したような設備状況の変化等に起因してシートバー１０の表面温度が１００℃低下した場合を想定し、冷却前のシートバー１０の表面温度を７００℃として、シートバー１０の温度経過をシミュレーションしたときの結果を示すものである。シートバー１０の搬送速度は図７（ａ）と同じである。このシミュレーションの結果から、冷却中にシートバー１０の表面温度は５７７℃まで低下し、制約条件（下限条件）の６００℃よりも２３℃低くなることが分かる。図７（ｃ）は、シートバー１０の温度に関する初期条件は図７（ｂ）のものと同じであるが、シートバー１０の搬送速度を図３（ａ），（ｂ）のシミュレーションにおける搬送速度よりも５０％高く修正しており、その結果、シートバー１０の表面温度が６００℃を下回るのは回避されている。 FIG. 7 shows a simulation example when the conveyance speed of the sheet bar 10 passed through the cooling device 43 is not corrected and when it is corrected. 7A shows that the sheet bar 10 to be cooled has a thickness of 80 mm, the surface temperature and the cross-sectional average temperature of the sheet bar 10 are both 800 ° C., and the water density of the slow cooling device 42 is 500 L / min · The simulation result of the temperature course of the sheet bar 10 when the conveyance speed is determined so that the surface temperature of the sheet bar 10 is cooled to 600 ° C. by the setup calculation under the initial condition of m 2 is shown. FIG. 7 (b) shows that the cross-sectional average temperature of the seat bar 10 is 800 ° C. and the same conditions as in FIG. 7 (a). Assuming a case where the temperature is lowered by 100 ° C., the surface temperature of the sheet bar 10 before cooling is set to 700 ° C., and the result when the temperature course of the sheet bar 10 is simulated is shown. The conveying speed of the sheet bar 10 is the same as that in FIG. From the results of this simulation, it can be seen that the surface temperature of the sheet bar 10 decreases to 577 ° C. during cooling, and is 23 ° C. lower than the constraint condition (lower limit condition) 600 ° C. In FIG. 7C, the initial conditions regarding the temperature of the sheet bar 10 are the same as those in FIG. 7B, but the conveyance speed of the sheet bar 10 is the conveyance speed in the simulations of FIGS. 3A and 3B. As a result, it is avoided that the surface temperature of the seat bar 10 falls below 600 ° C.
図８に、板厚８０ｍｍ、断面平均温度８００℃のシートバー１０において、冷却実施前のシートバー１０の表面温度の低下量（８００℃からの偏差）と、冷却装置４３の水量密度を５００〜３０００Ｌ／ｍｉｍ・ｍ２の範囲で変更したときの、冷却中のシートバー１０の表面の最低温度との関係を示す。このグラフから、同じ水量密度では、冷却前のシートバー１０の表面温度の低下量が大きいほど、冷却中のシートバー１０の表面の最低温度は低くなり、また、冷却前のシートバー１０の表面温度の低下量が同じでも冷却装置４３の水量密度が大きくなるほど、冷却中のシートバー１０の表面の最低温度は低くなることが分かる。 8, in the sheet bar 10 having a plate thickness of 80 mm and a cross-sectional average temperature of 800 ° C., the amount of decrease in the surface temperature of the sheet bar 10 before the cooling (deviation from 800 ° C.) and the water density of the cooling device 43 are 500 to The relationship with the minimum temperature of the surface of the sheet | seat bar 10 during cooling when changing in the range of 3000 L / mim * m < 2 > is shown. From this graph, at the same water content density, the lower the surface temperature of the sheet bar 10 before cooling, the lower the minimum temperature of the surface of the sheet bar 10 during cooling, and the surface of the sheet bar 10 before cooling. It can be seen that the minimum temperature of the surface of the sheet bar 10 during cooling decreases as the water density of the cooling device 43 increases even if the amount of temperature decrease is the same.
図９は、シートバー１０の実測表面温度が計算表面温度よりも低下している場合、冷却装置４３に通過させるシートバー１０の搬送速度をどの程度修正すればよいかの一例を示すマップである。冷却前のシートバー１０の表面温度の低下量が同じ場合、冷却装置４３の水量密度が大きいほど、搬送速度を大きく修正する必要があり、例えば、冷却直前のシートバー１０の実測表面温度が計算表面温度よりも１００℃低い場合には、当初のセットアップ計算で算出された搬送速度に対して１．５〜１．７倍程度まで搬送速度を増大させる必要がある。 FIG. 9 is a map showing an example of how much the conveyance speed of the sheet bar 10 passed through the cooling device 43 should be corrected when the measured surface temperature of the sheet bar 10 is lower than the calculated surface temperature. . When the amount of decrease in the surface temperature of the sheet bar 10 before cooling is the same, the greater the water density of the cooling device 43, the more the conveyance speed needs to be corrected. For example, the measured surface temperature of the sheet bar 10 immediately before cooling is calculated. When the temperature is lower than the surface temperature by 100 ° C., it is necessary to increase the conveyance speed to about 1.5 to 1.7 times the conveyance speed calculated in the initial setup calculation.
次に、冷却装置４３に通過させるシートバー１０の搬送速度の修正と冷却装置４３における使用する噴射ヘッダー数の修正を併用する場合について説明する。冷却装置４３に通過させるシートバー１０の搬送速度が過大となると、特に可逆式圧延機３１で圧延しながら冷却を行う場合に、圧延時に可逆式圧延機３１のローラとシートバー１０との間にスリップが発生し、圧延品質の低下等を招く虞がある。そこで、シートバー１０の搬送速度の修正量（以下、速度修正量を称す）が所定量以上、例えば４０％以上となる場合には、搬送速度の修正に加えて使用する噴射ヘッダー数の修正を併用することが好ましい。この際、図１０に示すように、使用する噴射ヘッダー数の変更がどの程度の速度修正量に相当するかの換算表をあらかじめ作成しておき、この換算表に基づき、速度修正量が上記所定量未満となるよう、噴射ヘッダー数の修正数を決定するのが好ましい。図１０（ａ）は、一例として、全噴射ヘッダー数が１０本である緩冷却装置４２の換算表であり、図１０（ｂ）は、一例として、全噴射ヘッダー数が６本である急冷却装置４１の換算表である。例えば、図１０（ａ）の換算表において、緩冷却装置４２における使用する噴射ヘッダー数を１０本から９本に減らすと、緩冷却装置４２に通過させるシートバー１０の搬送速度を１１％増大させることに等しくなる。 Next, the case where the correction of the conveying speed of the sheet bar 10 passed through the cooling device 43 and the correction of the number of ejection headers used in the cooling device 43 are used together will be described. When the conveying speed of the sheet bar 10 to be passed through the cooling device 43 is excessive, particularly when cooling is performed while rolling with the reversible rolling mill 31, between the roller of the reversible rolling mill 31 and the sheet bar 10 during rolling. There is a possibility that slip occurs and the rolling quality is lowered. Therefore, when the correction amount of the conveyance speed of the sheet bar 10 (hereinafter referred to as the speed correction amount) is a predetermined amount or more, for example, 40% or more, the number of injection headers to be used is corrected in addition to the correction of the conveyance speed. It is preferable to use together. At this time, as shown in FIG. 10, a conversion table indicating how much the speed correction amount corresponds to the change in the number of injection headers to be used is prepared in advance, and the speed correction amount is calculated based on the conversion table. It is preferable to determine the number of corrections for the number of injection headers so as to be less than the fixed amount. FIG. 10 (a) is a conversion table for the slow cooling device 42 having 10 total injection headers as an example, and FIG. 10 (b) is an example of rapid cooling having 6 total injection headers. 4 is a conversion table of the device 41. For example, in the conversion table of FIG. 10A, if the number of jet headers used in the slow cooling device 42 is reduced from 10 to 9, the transport speed of the sheet bar 10 passing through the slow cooling device 42 is increased by 11%. Is equal.
上記構成を備えた熱延鋼帯の製造装置およびそれを用いた熱延鋼帯の製造方法によれば、シートバー１０が冷却装置４３に進入する前に、シートバー１０の表面温度を測定し、その測定結果に基づき冷却装置１０に通過させるシートバー１０の搬送速度と冷却装置４３における使用する噴射ヘッダー数とのうちの少なくとも一方を修正するようにしたので、例えば冷却装置４３に進入するシートバー１０の表面温度が想定よりも低い場合には、シートバー１０の搬送速度を増大させたり使用する噴射ヘッダー数を減少させたりすることで冷却速度を緩やかにして冷却中にシートバー１０の表面温度が相変態温度を下回ることを確実に防止することができる。 According to the hot-rolled steel strip manufacturing apparatus having the above-described configuration and the hot-rolled steel strip manufacturing method using the same, the surface temperature of the seat bar 10 is measured before the seat bar 10 enters the cooling device 43. Since at least one of the conveying speed of the sheet bar 10 passed through the cooling device 10 and the number of jet headers used in the cooling device 43 is corrected based on the measurement result, for example, the sheet entering the cooling device 43 When the surface temperature of the bar 10 is lower than expected, the surface of the sheet bar 10 is cooled during cooling by increasing the conveying speed of the sheet bar 10 or decreasing the number of jetting headers to be used to make the cooling speed moderate. It is possible to reliably prevent the temperature from falling below the phase transformation temperature.
また、シートバー１０の搬送速度の修正量が所定量（好ましくは４０％）以上の場合に、シートバー１０の搬送速度の修正に加えて、使用する噴射ヘッダー数の修正を行うようにしたので、シートバー１０の搬送速度が過度に大きくなって可逆式圧延機３１のローラとシートバー１０との間にスリップが発生するのを防止することができる。 Further, when the correction amount of the conveyance speed of the sheet bar 10 is a predetermined amount (preferably 40%) or more, in addition to the correction of the conveyance speed of the sheet bar 10, the number of used injection headers is corrected. Further, it can be prevented that the conveying speed of the sheet bar 10 becomes excessively large and slip occurs between the roller of the reversible rolling mill 31 and the sheet bar 10.
さらに、使用する噴射ヘッダー数の修正数がどの程度の搬送速度の修正量に相当するかの換算表をあらかじめ作成しておき、この換算表に基づき、搬送速度の修正量が上記所定量未満となるよう、使用する噴射ヘッダー数の修正数を決定するようにしたので、シートバー１０の搬送速度の修正と使用する噴射ヘッダー数の修正とを併用する場合に、シートバー１０の搬送速度の修正量と使用する噴射ヘッダー数の修正数とを決定するための演算を容易に行うことができる。 Furthermore, a conversion table is prepared in advance indicating how much the correction number of the number of injection headers to be used corresponds to the correction amount of the conveyance speed. Based on this conversion table, the correction amount of the conveyance speed is less than the predetermined amount. Since the correction number of the injection header number to be used is determined, the correction of the conveyance speed of the sheet bar 10 is used in combination with the correction of the conveyance speed of the sheet bar 10 and the correction of the number of injection headers to be used. An operation for determining the quantity and the number of corrections for the number of injection headers to be used can be easily performed.
（実施例１）
次に、本発明の実施例について説明する。実施例１では、冷却装置４３に通過させるシートバー１０の搬送速度の修正を適用して、製品厚み２４ｍｍの熱延鋼帯（コイル）を製造した。具体的には、図１に示す熱延鋼帯の製造設備（適宜、図１１を参照）を用いて、圧延素材を連続式加熱炉1で１１５０℃まで加熱し、その後、粗圧延機群３で板厚６０ｍｍまで圧延してシートバー１０とし、このシートバー１０を仕上圧延機群６で制御圧延圧下率６０％として板厚２４ｍｍまで圧延した。粗圧延機群３では表１に記載の板厚スケジュールで粗圧延を実施し、奇数パスの出側で冷却装置４３の急冷却装置４１または緩冷却装置４２を用いて、仕上圧延工程前までにシートバーの表面温度が８５０℃±１０℃となるまで冷却した。ここで、実施例１では、図１（ａ）および図１（ｂ）に示す位置に温度計４５，４６を設置して、可逆式圧延機３１および冷却装置４３にシートバー１０を進入させる直前のシートバー１０の表面温度を測定し、測定したシートバー１０の表面温度に基づき圧延速度および冷却装置４３に通過させるシートバー１０の搬送速度を修正した。表２に、セットアップ計算により得られた、圧延前に想定されていたシートバー１０の表面温度（計算表面温度）と温度計により測定されたシートバー１０の表面温度（実測表面温度）との差、および冷却装置４３に通過させるシートバー１０の速度修正量（最初のセットアップ計算で得られたシートバー１０の搬送速度に対する修正後のシートバー１０の搬送速度の割合［％］）の一例を示す。
Example 1
Next, examples of the present invention will be described. In Example 1, the correction of the conveyance speed of the sheet bar 10 passed through the cooling device 43 was applied to manufacture a hot-rolled steel strip (coil) having a product thickness of 24 mm. Specifically, the rolling material is heated to 1150 ° C. in the continuous heating furnace 1 using the hot-rolled steel strip manufacturing facility shown in FIG. Then, the sheet bar 10 was rolled to a sheet thickness of 60 mm, and the sheet bar 10 was rolled to a sheet thickness of 24 mm with a finish rolling mill group 6 with a controlled rolling reduction of 60%. In the rough rolling mill group 3, rough rolling is performed according to the sheet thickness schedule shown in Table 1, and the rapid cooling device 41 or the slow cooling device 42 of the cooling device 43 is used before the finish rolling process on the exit side of the odd number of passes. The sheet bar was cooled until the surface temperature reached 850 ° C. ± 10 ° C. Here, in Example 1, just before the thermometers 45 and 46 are installed at the positions shown in FIGS. 1A and 1B, the sheet bar 10 is entered into the reversible rolling mill 31 and the cooling device 43. The surface temperature of the sheet bar 10 was measured, and the rolling speed and the conveying speed of the sheet bar 10 passed through the cooling device 43 were corrected based on the measured surface temperature of the sheet bar 10. Table 2 shows the difference between the surface temperature of the sheet bar 10 (calculated surface temperature) assumed by the setup calculation and the surface temperature of the sheet bar 10 (measured surface temperature) measured by the thermometer. And an example of the speed correction amount of the sheet bar 10 passed through the cooling device 43 (the ratio [%] of the corrected conveyance speed of the sheet bar 10 to the conveyance speed of the sheet bar 10 obtained in the initial setup calculation). .
比較例１は、実施例１と同じ板厚スケジュール（表１）に従って粗圧延を行うが、冷却装置４３に通過させるシートバー１０の搬送速度は修正せずに冷却を行ったものである。 In Comparative Example 1, rough rolling is performed according to the same sheet thickness schedule (Table 1) as Example 1, but cooling is performed without correcting the conveying speed of the sheet bar 10 that is passed through the cooling device 43.
（実施例２）
実施例２では、冷却装置４３に通過させるシートバー１０の搬送速度の修正と冷却装置４３における使用する噴射ヘッダー数の修正との両方を適用して製品厚み１８ｍｍの熱延鋼帯（コイル）を製造した。具体的には、図１に示す熱延鋼帯の製造設備（適宜、図１１を参照）を用いて、圧延素材を連続式加熱炉１で１１７０℃まで加熱し、その後、粗圧延機群３で表３に記載の板厚スケジュールで粗圧延を実施し、奇数パスの出側で冷却装置４３の急冷却装置４１または緩冷却装置４２を用いて、仕上圧延工程前までにシートバー１０の表面温度が８５０℃±１０℃となるまで冷却した。シートバー１０の板厚が薄くなる５パス目以降は、シートバー１０の長さが長くなるため、可逆式圧延機３１で圧延しながら同時に水冷を実施した。ここで、圧延速度と冷却装置４３に通過させるシートバーの搬送速度とは互いに一致させる必要がある。一方、可逆式圧延機３１の、シートバー１０の噛み込み速度を高くすると、スリップが発生しやすくなるため、圧延速度は所定の範囲内に調整する必要がある。そこで、実施例２ではシートバー１０の速度修正量が所定量（４０％）以上の場合に、シートバー１０の搬送速度の修正に加えて使用する噴射ヘッダー数の修正を適用した。具体的には、実施例１と同様に、図１（ａ）および図１（ｂ）に示す位置に温度計４５，４６を設置して、可逆式圧延機３１および冷却装置４３にシートバー１０を進入させる直前の該シートバー１０の表面温度を測定して、圧延速度、搬送速度および使用する噴射ヘッダー数を修正した。
(Example 2)
In Example 2, both the correction of the conveying speed of the sheet bar 10 passed through the cooling device 43 and the correction of the number of jet headers used in the cooling device 43 are applied to form a hot-rolled steel strip (coil) having a product thickness of 18 mm. Manufactured. Specifically, the rolling material is heated to 1170 ° C. in the continuous heating furnace 1 using the hot-rolled steel strip manufacturing facility shown in FIG. The rough rolling is carried out according to the sheet thickness schedule shown in Table 3, and the surface of the sheet bar 10 before the finish rolling process using the rapid cooling device 41 or the slow cooling device 42 of the cooling device 43 on the odd-numbered-pass side. Cooled until the temperature reached 850 ° C. ± 10 ° C. Since the length of the sheet bar 10 is increased after the fifth pass when the plate thickness of the sheet bar 10 is reduced, water cooling is simultaneously performed while rolling with the reversible rolling mill 31. Here, it is necessary that the rolling speed and the conveying speed of the sheet bar passed through the cooling device 43 coincide with each other. On the other hand, if the biting speed of the sheet bar 10 of the reversible rolling mill 31 is increased, slipping is likely to occur, so the rolling speed needs to be adjusted within a predetermined range. Therefore, in the second embodiment, when the speed correction amount of the sheet bar 10 is a predetermined amount (40%) or more, the correction of the number of injection headers to be used is applied in addition to the correction of the conveyance speed of the sheet bar 10. Specifically, as in Example 1, thermometers 45 and 46 are installed at the positions shown in FIGS. 1A and 1B, and the sheet bar 10 is installed in the reversible rolling mill 31 and the cooling device 43. The surface temperature of the sheet bar 10 immediately before entering was measured to correct the rolling speed, the conveyance speed, and the number of jet headers to be used.
本実施例で用いた冷却装置４３の修正前の噴射ヘッダー数は、緩冷却装置４２が１０本、急冷却装置４１が６本である。表４に、圧延前に想定していたシートバー１０の表面温度（計算表面温度）と温度計４５，４６により測定されたシートバー１０の実測表面温度との差、シートバー１０の速度修正量、および使用する噴射ヘッダー数を示す。使用する噴射ヘッダー数の決定は次のように行った。まず、計算表面温度と実測表面温度との差により、シートバー１０の搬送速度の修正のみ実施する場合の速度修正量を算出する（表４中の「速度修正量（ａ）」。次にこの速度修正量（ａ）が４０％以上のときに、使用する噴射ヘッダー数の修正を併用し、速度修正量が４０％を超えないようにする。使用する噴射ヘッダー数の決定は、図１０（ａ）で示した緩冷却装置４２用の換算表および図１０（ｂ）で示した急冷却装置４１用の換算表をそれぞれ用いて行った。一例として、表４中の「速度修正量（ａ）が４０％以上である圧延５パス目の事例で説明する。圧延５パス目で上流側に搬送する速度修正量（ａ）は＋４９％となる。この圧延パスでは緩冷却装置４２を使用するため、図１０（ａ）の換算表を参照し、使用する噴射ヘッダー数を１０本から９本に１本減とすれば、速度修正量を１１％増大させるのと同等の効果が得られる。このように、使用する噴射ヘッダー数を１本減とすれば、速度修正量は＋４９％から＋３８％（１１％減）とすることができ、最終的な速度修正量（表４中の「速度修正量（ｂ）」）を４０％未満に抑えることができる。他の圧延パスも同様に実施し、使用する噴射ヘッダー数と速度修正量（ｂ）を算出した。 The number of injection headers before correction of the cooling device 43 used in the present embodiment is 10 for the slow cooling device 42 and 6 for the rapid cooling device 41. Table 4 shows the difference between the surface temperature (calculated surface temperature) of the sheet bar 10 assumed before rolling and the actual surface temperature of the sheet bar 10 measured by the thermometers 45 and 46, and the speed correction amount of the sheet bar 10. , And the number of jet headers used. The number of injection headers to be used was determined as follows. First, based on the difference between the calculated surface temperature and the actually measured surface temperature, a speed correction amount when only correcting the conveyance speed of the sheet bar 10 is calculated (“speed correction amount (a)” in Table 4). When the speed correction amount (a) is 40% or more, the correction of the number of injection headers to be used is used together so that the speed correction amount does not exceed 40%. The conversion table for the slow cooling device 42 shown in a) and the conversion table for the rapid cooling device 41 shown in Fig. 10B were used, respectively. ) Is 40% or more In the case of the 5th rolling pass, the speed correction amount (a) conveyed upstream in the 5th rolling pass is + 49%, and the slow cooling device 42 is used in this rolling pass. Therefore, refer to the conversion table in FIG. If the number is reduced from 10 to 9, the same effect as increasing the speed correction amount by 11% can be obtained. The amount can be + 49% to + 38% (11% decrease), and the final speed correction amount (“speed correction amount (b)” in Table 4) can be suppressed to less than 40%. The rolling pass was performed in the same manner, and the number of jetting headers used and the speed correction amount (b) were calculated.
比較例２は、実施例２と同じ板厚スケジュール（表３）に従って粗圧延を行うが、冷却装置４３に通過させるシートバー１０の搬送速度および使用する噴射ヘッダー１０は共に修正せずに冷却を行ったものである。 In Comparative Example 2, rough rolling is performed in accordance with the same sheet thickness schedule (Table 3) as Example 2, but cooling is performed without correcting both the conveying speed of the sheet bar 10 passed through the cooling device 43 and the jet header 10 to be used. It is what I did.
表５に、実施例１，２および比較例１，２にそれぞれ製造されたコイルからサンプルを採取し、表層の割れを目視と磁粉探傷試験により評価した結果を示す。これによると、本発明を適用しない場合、６％のコイルに表層割れを認めたが、本発明を適用したコイルでは表層割れは０％であった。 Table 5 shows the results of taking samples from the coils manufactured in Examples 1 and 2 and Comparative Examples 1 and 2, respectively, and evaluating the cracks in the surface layer by visual inspection and a magnetic particle inspection test. According to this, when the present invention was not applied, surface cracks were observed in 6% of the coils, but in the coils to which the present invention was applied, the surface cracks were 0%.
以上図示例に基づき本発明を説明したが、本発明はこれに限定されず、特許請求の範囲の記載範囲内で適宜変更、追加することができる。例えば、上記実施形態では、シートバー１０の実測表面温度が計算表面温度よりも低い場合につき説明したが、シートバー１０の実測表面温度が計算表面温度よりも高い場合には、冷却装置４３に進入させるシートバー１０の搬送速度を減少させたり使用する噴射ヘッダー数を増加させたりすることで、冷却速度を上げることができる。また、シートバー１０の表面温度を測定する温度計の配置位置は図示例に限定されず、冷却装置４３からみて可逆式圧延機３１の反対側と、可逆式圧延機３１および冷却装置４３相互間と、可逆式圧延機３１からみて冷却装置４３の反対側とのうちの少なくとも１箇所に設置すればよく、これらの３箇所全てに設置してもよい。さらに、急冷却装置４１および緩冷却装置４２による冷却は、冷却装置４１，４２に向けて送り出される全ての圧延パスに関連して行わなくてもよく、水冷による温度降下量が大きく、仕上げ圧延機到達時の温度が仕上げ圧延の予定開始温度を下回る場合は、任意のパスの水冷を実施しなくてもよい。さらに、上記実施形態では、可逆式圧延機３１に対して近い位置に急冷却装置４１を、遠い位置に緩冷却装置４２をそれぞれ配置したが、粗圧延機３１，３２の間隔が十分に長い場合等では、可逆式圧延機３１に対して近い位置に緩冷却装置４２を、遠い位置に急冷却装置４１をそれぞれ配置してもよい。 Although the present invention has been described based on the illustrated examples, the present invention is not limited to this, and can be appropriately changed and added within the scope of the claims. For example, in the above embodiment, the case where the measured surface temperature of the seat bar 10 is lower than the calculated surface temperature has been described. However, when the measured surface temperature of the seat bar 10 is higher than the calculated surface temperature, the cooling device 43 is entered. The cooling rate can be increased by decreasing the conveying speed of the sheet bar 10 to be used or increasing the number of jet headers to be used. In addition, the arrangement position of the thermometer for measuring the surface temperature of the sheet bar 10 is not limited to the illustrated example, and the opposite side of the reversible rolling mill 31 from the cooling device 43 and between the reversible rolling mill 31 and the cooling device 43. And it should just install in at least 1 place of the reversible rolling mill 31 and the other side of the cooling device 43, and may install in all these 3 places. Further, the cooling by the rapid cooling device 41 and the slow cooling device 42 does not have to be performed in relation to all rolling passes sent out toward the cooling devices 41, 42, the amount of temperature drop due to water cooling is large, and the finish rolling mill When the temperature at the time of arrival is lower than the scheduled start temperature of finish rolling, water cooling of an arbitrary pass may not be performed. Furthermore, in the said embodiment, although the rapid cooling apparatus 41 was arrange | positioned in the position near with respect to the reversible rolling mill 31, and the slow cooling apparatus 42 in the distant position, respectively, when the space | interval of the rough rolling mills 31 and 32 is sufficiently long For example, the slow cooling device 42 may be disposed near the reversible rolling mill 31 and the rapid cooling device 41 may be disposed far away.
かくして本発明によれば、制御圧延に先立って行う冷却中にシートバーの表層が相変態温度を下回ることを確実に防止しつつ、制御圧延開始までに要する時間を低減して能率よく熱延鋼帯を製造することができる。 Thus, according to the present invention, the surface layer of the sheet bar is reliably prevented from falling below the phase transformation temperature during cooling prior to controlled rolling, and the time required to start controlled rolling is efficiently reduced and hot rolled steel efficiently. Bands can be manufactured.
１ 連続加熱炉
２ サイジングプレス
３ 粗圧延機群
４ エッジャー
５ クロップシャー
６ 仕上げ圧延機群
７ ランアウトテーブル
８ コイラー
１０ シートバー
３１ 可逆式圧延機
３２ 非可逆式圧延機
３３，３５ 放射温度計
３６，３７ スプレーヘッダー
４１ 急冷却装置
４２ 緩冷却装置
４３ 冷却装置
４５，４６，４７ 温度計
DESCRIPTION OF SYMBOLS 1 Continuous heating furnace 2 Sizing press 3 Rough rolling mill group 4 Edger 5 Crop shear 6 Finish rolling mill group 7 Runout table 8 Coiler 10 Sheet bar 31 Reversible rolling mill 32 Non-reversible rolling mill 33,35 Radiation thermometer 36,37 Spray header 41 Rapid cooling device 42 Slow cooling device 43 Cooling device 45, 46, 47 Thermometer
Claims (8)
被圧延材の表面温度を測定する温度計を、前記冷却装置からみて前記可逆式圧延機の反対側と、前記可逆式圧延機および前記冷却装置相互間と、前記可逆式圧延機からみて前記冷却装置の反対側とのうちの少なくとも１箇所に設置し、
前記温度計により前記冷却装置による冷却直前の被圧延材の表面温度を実測し、
前記温度計による測定で得られた被圧延材の実測表面温度に基づき、前記冷却装置での冷却中に被圧延材の表面温度が被圧延材の表層の相変態に関連した所定の基準温度以上に維持されるように、前記冷却装置に通過させる際の被圧延材の搬送速度と前記冷却装置における使用する噴射ヘッダー数とのうちの少なくとも一方を修正することを特徴とする熱延鋼帯の製造方法。 A rough rolling group including a plurality of rough rolling mills including at least one reversible rolling mill, and a cooling device disposed on the upstream side or the downstream side of the reversible rolling mill, wherein the cooling device is in a rolling direction. in which is disposed next to each other, suddenly the rapidly cooling the material to be rolled by the slow cooling device and 1000L / min · m 2 or more water density of slow cooling the material to be rolled at a water flow rate of less than 1000L / min · m 2 Using a production facility for hot-rolled steel strip, comprising a cooling device, the material to be rolled is slowly cooled by the slow cooling device as the rolling pass of the reversible rolling mill is repeated, and then according to the reduction in sheet thickness A method of manufacturing a hot-rolled steel strip that is rapidly cooled by the rapid cooling device,
A thermometer for measuring the surface temperature of the material to be rolled is the opposite side of the reversible rolling mill when viewed from the cooling device, the reversible rolling mill and the cooling device, and the cooling when viewed from the reversible rolling mill. Installed in at least one of the opposite sides of the device,
Measure the surface temperature of the material to be rolled immediately before cooling by the cooling device with the thermometer,
Based on the measured surface temperature of the material to be rolled obtained by measurement with the thermometer, the surface temperature of the material to be rolled is not less than a predetermined reference temperature related to the phase transformation of the surface layer of the material to be rolled during cooling by the cooling device. To maintain at least one of the conveyance speed of the material to be rolled when passing through the cooling device and the number of jet headers used in the cooling device, Production method.
前記冷却装置からみて前記可逆式圧延機の反対側と、前記可逆式圧延機および前記冷却装置相互間と、前記可逆式圧延機からみて前記冷却装置の反対側とのうちの少なくとも１箇所に設置された、被圧延材の表面温度を実測する温度計と、
前記温度計による測定で得られた被圧延材の実測表面温度に基づき、前記冷却装置での冷却中に被圧延材の表面温度が被圧延材の表層の相変態に関連した所定の基準温度以上に維持されるように、前記冷却装置に通過させる際の被圧延材の搬送速度と前記冷却装置における使用する噴射ヘッダー数とのうちの少なくとも一方を修正する修正手段と、を備えることを特徴とする熱延鋼帯の製造設備。 A rough rolling group composed of a plurality of rough rolling mills including at least one reversible rolling mill, and a cooling device disposed on the upstream side or the downstream side of the reversible rolling mill, the cooling device in the rolling direction slow cooling device and 1000L / min · m 2 or more rapid cooling device for quenching the material to be rolled at a water density of slow cooling the material to be rolled at 1000L / min · m 2 less than water density arranged next to each other Ri Do from the involves the rolled material to repeated rolling passes of the reversible rolling mill, after slow cooling by the slow cooling unit, rapidly cooled by the rapid cooling device according to the thickness decrease, the hot rolling Steel strip manufacturing equipment,
Installed in at least one of the opposite side of the reversible rolling mill viewed from the cooling device, between the reversible rolling mill and the cooling device, and the opposite side of the cooling device viewed from the reversible rolling mill. A thermometer that actually measures the surface temperature of the material to be rolled,
Based on the measured surface temperature of the material to be rolled obtained by measurement with the thermometer, the surface temperature of the material to be rolled is not less than a predetermined reference temperature related to the phase transformation of the surface layer of the material to be rolled during cooling by the cooling device. And a correction means for correcting at least one of the conveying speed of the material to be rolled when passing through the cooling device and the number of jet headers used in the cooling device. Manufacturing equipment for hot rolled steel strip.
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