JP2013240808A - Continuous hot rolling facility - Google Patents

Continuous hot rolling facility Download PDF

Info

Publication number
JP2013240808A
JP2013240808A JP2012115372A JP2012115372A JP2013240808A JP 2013240808 A JP2013240808 A JP 2013240808A JP 2012115372 A JP2012115372 A JP 2012115372A JP 2012115372 A JP2012115372 A JP 2012115372A JP 2013240808 A JP2013240808 A JP 2013240808A
Authority
JP
Japan
Prior art keywords
cooling
steel strip
temperature
cooling device
water
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2012115372A
Other languages
Japanese (ja)
Other versions
JP5991023B2 (en
Inventor
Tokunori Kanemura
篤謙 金村
Satoshi Kamioka
悟史 上岡
Hidekazu Okubo
英和 大久保
Masahide Watabe
真英 渡部
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Original Assignee
JFE Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by JFE Steel Corp filed Critical JFE Steel Corp
Priority to JP2012115372A priority Critical patent/JP5991023B2/en
Publication of JP2013240808A publication Critical patent/JP2013240808A/en
Application granted granted Critical
Publication of JP5991023B2 publication Critical patent/JP5991023B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Abstract

PROBLEM TO BE SOLVED: To suppress defective parts in the nose and tail end parts too while performing suppression of the variation of plate thickness and suppression of uneven cooling.SOLUTION: A continuous hot rolling facility includes: a connecting device 4 for connecting the nose of a succeeding material rewound from a sheet bar coiler 3 with the tail end of the preceding material; a heating device 5 for heating a steel strip 9; a finishing mill 6 for performing finish rolling of the steel strip 9 heated with the heating device 5 to the sheet thickness of 1.8 mm; and a cooling device for cooling the steel strip 9 rolled with the finishing mill 6 during conveyance with a run out table 11. The cooling device is provided with a first cooling device 7 and a second cooling device 8. The first cooling device cools the surface temperature of the steel strip within the temperature range of a film boiling region with cooling water at the flow rate of water per unit area of 350-1,200 L/(min×m) and the second cooling device 8 cools the surface temperature of the steel strip to ≤ 450°C with the cooling water of the flow rate of water per unit area of ≥2,000 L/(min×m).

Description

本発明は、板厚1.8mm以下の薄板に熱間仕上圧延された熱延鋼帯を冷却して500℃以下の巻取り温度とする連続熱間圧延設備に関し、板厚変動、冷却ムラを抑制した薄物熱延鋼帯の製造に関する技術である。   The present invention relates to a continuous hot rolling facility that cools a hot-rolled steel strip hot-rolled to a thin plate having a thickness of 1.8 mm or less to a coiling temperature of 500 ° C. or less, and is capable of reducing thickness variation and cooling unevenness. This is a technology related to the production of suppressed thin hot-rolled steel strip.

熱延鋼帯の製造では、加熱装置で高温加熱した鋼板を目的とするサイズになるよう圧延し、その後、材質調整などの観点からランナウトテーブルで水冷却される。すなわち、上記水冷の目的は、主に鋼帯の析出物や変態組織を制御することにより目的の強度、延びなど材質を調整するために行われている。特に、冷却終了温度(巻取り温度)を精度よく制御することは目的の材質をバラツキ無く製造するために最も重要である。   In the production of a hot-rolled steel strip, a steel plate heated at a high temperature with a heating device is rolled to a desired size, and then water-cooled with a run-out table from the viewpoint of material adjustment. That is, the purpose of the water cooling is performed to adjust the material such as the intended strength and elongation mainly by controlling the precipitates and transformation structure of the steel strip. In particular, it is most important to accurately control the cooling end temperature (winding temperature) in order to produce a desired material without variation.

一方、水冷工程では冷却媒体としてコストが安い水を使うことが多い。この場合、冷却終了温度(巻取り温度)を低く設定すると温度ムラの発生が問題となり、板厚が薄いほど顕著となる。また、鋼帯の先端部から急冷を行うと先端部での頭折れが問題となり、先端部から、目的とする冷却終了温度に冷却することは出来ない。
上記温度ムラ発生の第1の原因は、冷却水は鋼帯に被水した時点で沸騰するが、ある温度を境に沸騰形態が変わり伝熱能力の変化が起こり、この温度よりも低い温度まで冷却した場合、冷却終了温度を精度良く制御できないことがあるためである。
On the other hand, in the water cooling process, water having a low cost is often used as a cooling medium. In this case, if the cooling end temperature (winding temperature) is set low, the occurrence of temperature unevenness becomes a problem, and becomes more noticeable as the plate thickness is thinner. In addition, if the steel strip is rapidly cooled from the front end portion, head breakage at the front end portion becomes a problem, and it is not possible to cool from the front end portion to the target cooling end temperature.
The first cause of the above temperature unevenness is that the cooling water boils when it gets wet with the steel strip, but the boiling form changes at a certain temperature and the heat transfer capacity changes, and the temperature is lower than this temperature. This is because, when cooled, the cooling end temperature may not be accurately controlled.

ここで鋼帯を水冷した場合の沸騰形態について説明する。鋼帯表面温度が高い状態では膜沸騰、低温領域では核沸騰、高温領域と低温領域の間の中間温度領域では遷移沸騰となっている。高温状態で発生する膜沸騰では鋼帯表面と冷却水の間に蒸気膜が発生し、この蒸気膜内の熱伝導により伝熱がなされる状態となって、冷却能力は低い。一方、低温状態で発生する核沸騰では、鋼帯表面と冷却水は直接接触し且つ鋼帯表面から冷却水の一部が蒸発して出来た蒸気泡が発生し直ぐ周りの冷却水により凝縮され消滅するといった複雑な現象が起こっており、蒸気泡の生成・消滅に伴う冷却水の攪拌が発生することから、極めて高い冷却能力を有する。なお、膜沸騰の温度領域と核沸騰の温度領域との間の中間温度領域では、膜沸騰と核沸騰が混在した状態である遷移沸騰状態となる。遷移沸騰状態では、核沸騰及び膜沸騰と異なり、鋼帯温度が低くなるにつれ熱流束が大きくなる現象が起こる。材質制御の観点から、温度によって冷却速度を変化することは好ましくなく、且つ膜沸騰状態から遷移沸騰状態に遷移する温度領域で冷却を停止させようとすると、遷移沸騰領域では加速度的に冷却速度が高くなることから、わずかに冷却制御時間が長くなっただけで鋼帯温度は狙いより大きく低くなってしまうなどの問題がある。   Here, the boiling mode when the steel strip is cooled with water will be described. Film boiling occurs when the steel strip surface temperature is high, nucleate boiling occurs in the low temperature region, and transition boiling occurs in the intermediate temperature region between the high temperature region and the low temperature region. In film boiling that occurs in a high temperature state, a vapor film is generated between the steel strip surface and the cooling water, and heat is transferred by heat conduction in the vapor film, so that the cooling capacity is low. On the other hand, in nucleate boiling that occurs in a low temperature state, the steel strip surface and cooling water are in direct contact with each other, and vapor bubbles formed by evaporation of a part of the cooling water from the steel strip surface are generated and condensed immediately by the surrounding cooling water. A complicated phenomenon such as disappearance occurs, and the cooling water is agitated due to the generation and disappearance of the vapor bubbles, so that it has a very high cooling capacity. In the intermediate temperature region between the film boiling temperature region and the nucleate boiling temperature region, a transition boiling state in which film boiling and nucleate boiling are mixed is obtained. In the transition boiling state, unlike nucleate boiling and film boiling, a phenomenon occurs in which the heat flux increases as the steel strip temperature decreases. From the viewpoint of controlling the material, it is not preferable to change the cooling rate depending on the temperature. Since it becomes high, there is a problem that the temperature of the steel strip becomes much lower than intended when the cooling control time is slightly increased.

また、冷却前の鋼帯に、圧延などで局所的に温度の低い領域があった場合、冷却中に表面温度はこの温度の低い領域が早いタイミングで遷移沸騰に移行するため、温度偏差は増大する。一般的なランナウトテーブルに設置されている冷却装置では、この遷移沸騰開始温度がおおよそ500℃程度である。
上記温度ムラ発生の第2の原因として、鋼帯上の滞留水に起因するものがある。これは、通常のランナウトテーブルでは特に上面から冷却する場合、円管ラミナーやスリットラミナー等の冷却装置で冷却するが、鋼帯に衝突した冷却水は、鋼帯に乗ったまま鋼帯とともに鋼帯進行方向に流出していく。上記鋼帯上の冷却水は通常、水切りパージなどで排除するものの、当該排除処理は、冷却水を鋼帯に衝突させた地点から離れたところで実施するため、その間で、鋼帯に水が乗っている部分だけ相対的に多く冷えてしまう。特に、500℃以下の低温度領域の場合、この滞留水が膜沸騰状態から遷移沸騰状態に変化するため冷却能力が高くなり、滞留水が乗っていた部位と乗っていなかった部位とで大きな温度
偏差が生じる。以上の理由から、遷移沸騰開始温度である500℃以下で熱延鋼帯を冷却終了させようとするとコイル内の温度バラツキが大きくなる。
In addition, when there is a locally low temperature region in the steel strip before cooling due to rolling or the like, the temperature deviation increases because the surface temperature shifts to transition boiling at an early timing during this cooling. To do. In a cooling device installed on a general run-out table, this transition boiling start temperature is about 500 ° C.
As a second cause of the occurrence of the temperature unevenness, there is one caused by stagnant water on the steel strip. This is because a normal run-out table is cooled by a cooling device such as a circular tube laminar or a slit laminator, especially when cooling from the upper surface, but the cooling water that has collided with the steel strip stays on the steel strip along with the steel strip. It flows out in the direction of travel. Although the cooling water on the steel strip is usually removed by draining purge or the like, the removal process is performed away from the point where the cooling water collided with the steel strip. Only the part where it is cooled down relatively much. In particular, in the case of a low temperature region of 500 ° C. or lower, this stagnant water changes from a film boiling state to a transition boiling state, so that the cooling capacity is high, and a large temperature is generated between the part where the stagnant water is on and the part where it is not. Deviation occurs. For the above reasons, if the hot-rolled steel strip is finished cooling at 500 ° C. or less, which is the transition boiling start temperature, the temperature variation in the coil increases.

また、近年、高強度で板厚が薄い材料のニーズが高まっており、板厚を1.8mm以下の薄板とし、圧延後の鋼板を急速冷却して、組織の微細化や変態組織の制御によって、鋼板の強度や加工性を上げる技術が検討されている。その際、板厚が薄い領域では、先端・尾端部の厚み変動、冷却ムラもさらに発生しやすい。特に先端部での通板性を確保するために、通板の加減速があるので最終温度目標が従来550℃以上となるよう制御している。この結果、先端部の切捨て量は100m以上にも及ぶという問題点がある。   In recent years, there has been an increasing demand for materials with high strength and thin plate thickness. The plate thickness is 1.8 mm or less, and the rolled steel plate is rapidly cooled to refine the structure and control the transformation structure. Techniques for increasing the strength and workability of steel sheets are being studied. At that time, in the region where the plate thickness is thin, fluctuations in the thickness of the tip and tail ends and cooling unevenness are more likely to occur. In particular, in order to ensure the plate-passability at the tip, there is acceleration / deceleration of the plate-pass, so that the final temperature target is conventionally controlled to be 550 ° C. or higher. As a result, there is a problem that the amount of cutting off at the tip reaches as much as 100 m or more.

ここで従来の連続熱間圧延設備としては、特許文献1、2などに記載の設備がある。
特許文献1には、薄スケール鋼板の作成を目的として、大容量の冷却をランナウトテーブル上で行うことで、薄スケール化及び温度の均一化を狙うということが記載されている。すなわち、空走区間で生成されるスケールを剥離し、冷却帯におけるスケール発生を抑制するために急速冷却を行うことが記載されている。
Here, as a conventional continuous hot rolling facility, there are facilities described in Patent Documents 1 and 2, for example.
Patent Document 1 describes that, for the purpose of producing a thin-scale steel plate, a large-capacity cooling is performed on a run-out table so as to aim for a thin scale and uniform temperature. That is, it describes that rapid cooling is performed in order to peel off the scale generated in the idle running section and suppress the generation of scale in the cooling zone.

特許文献2には、例えば鋼帯の板厚が3.2mm程度の鋼帯を対象として、低温領域での大流量密度冷却を行うことで、温度バラツキの少ない鋼板を製造することが記載されている。   Patent Document 2 describes that, for example, a steel strip having a steel strip thickness of about 3.2 mm is manufactured to produce a steel plate with little temperature variation by performing large flow density cooling in a low temperature region. Yes.

特開平08−332514号公報Japanese Patent Laid-Open No. 08-332514 特開2008−110353号公報JP 2008-110353 A

特許文献1に記載の技術では、鋼帯の上面に載った滞留水による温度ムラなどは低減できるものの、ランナウトテーブル上での冷却を450℃までしか行うことが出来ない。また本発明が対象とする板厚1.8mm以下の薄鋼板を安定して製造できないおそれがある。
また特許文献2に記載の技術では、薄板を対象とした場合に板厚変動がどの程度まであるのかは不明であり、また、先端・尾端部については通板性確保の観点から冷却終了温度を上げて操業を行うため先端・尾端部の不良部が通板した鋼帯分だけ発生して、歩留まりが低いという問題がある。
With the technique described in Patent Document 1, although temperature unevenness due to stagnant water on the upper surface of the steel strip can be reduced, cooling on the run-out table can only be performed up to 450 ° C. Moreover, there exists a possibility that the thin steel plate of 1.8 mm or less thickness targeted by this invention cannot be manufactured stably.
Further, in the technique described in Patent Document 2, it is unclear to what extent the plate thickness variation occurs when a thin plate is used. In order to perform the operation by raising the height, there is a problem that the defective portion at the tip and tail ends is generated only for the steel strip through which the plate is passed, and the yield is low.

本発明は、上記のような点に着目してなされたもので、板厚変動の抑制及び冷却ムラの抑制を行いつつ先端・尾端部の不良部も抑制することを目的とする。   The present invention has been made paying attention to the above points, and an object of the present invention is to suppress defective portions at the tip and tail ends while suppressing variations in plate thickness and uneven cooling.

上記課題を解決するために、本発明は、仕上圧延後の鋼帯を巻取り・巻戻しするシートバーコイラと、シートバーコイラから巻き戻された後行材の先端部と先行材の尾端部とを接合する接合装置と、接合装置の下流に配置されて搬送されてくる鋼帯を加熱する加熱装置と、加熱装置で加熱された鋼帯を板厚1.8mm以下に仕上圧延を行う仕上圧延機と、仕上圧延機で圧延された鋼帯をランナウトテーブルで搬送中に冷却する冷却装置と、を備え、上記冷却装置は、上流側の第1冷却装置と、下流側の第2冷却装置とを備え、上記第1冷却装置は、水流密度が350L/(分・m)以上1200L/(分・m)以下の冷却水で、鋼帯表面温度を膜沸騰領域の温度範囲内で冷却を行い、上記第2冷却装置は、水流密度が2000L/(分・m)以上の冷却水で、鋼帯表面温度を450℃以下に冷却することを特徴とする連続熱間圧延設備を提供するものである。 In order to solve the above-described problems, the present invention provides a sheet bar coiler that winds and rewinds a steel strip after finish rolling, a leading end portion of a succeeding material unwound from the sheet bar coiler, and a tail end of a preceding material. A joining device that joins the parts, a heating device that heats the steel strip disposed downstream of the joining device, and finish-rolling the steel strip heated by the heating device to a thickness of 1.8 mm or less A finish rolling mill, and a cooling device that cools the steel strip rolled by the finish rolling mill while being transported by the runout table. The cooling device includes a first cooling device on the upstream side and a second cooling on the downstream side. and a device, the first cooling device, water flow density of 350L / (min · m 2) or more 1200L / (min · m 2) or less of the cooling water within a temperature range of film boiling region strip surface temperature The second cooling device has a water flow density of 2000 L / (min. · M 2) or more in the cooling water, and it provides a continuous hot rolling equipment, characterized by cooling the steel strip surface temperature of 450 ° C. or less.

本発明によれば、仕上圧延機の上流で順次鋼帯を接合することで、連続的に鋼帯の圧延及び冷却が実施される。この結果、最先端の先端部及び最後端の鋼帯の後端部を除き、鋼帯の先尾端部で速度調整が不要となって不良部が大幅に低減すると共に、冷却装置による冷却の際の速度変動による冷却制御の精度悪化を抑えることが出来る。特に、本発明が対象とする薄板は温度変化に敏感であるため特に本発明は有効である。   According to the present invention, the steel strip is continuously rolled and cooled by sequentially joining the steel strip upstream of the finish rolling mill. As a result, speed adjustment is unnecessary at the leading end of the steel strip, except for the most advanced tip and the rear end of the rearmost steel strip, and the defective portion is greatly reduced. It is possible to suppress the deterioration of the accuracy of the cooling control due to the speed fluctuation. In particular, the present invention is particularly effective because the thin plate targeted by the present invention is sensitive to temperature changes.

更に、冷却装置として第1冷却装置と第2冷却装置を備え、第1冷却装置で膜沸騰領域の温度範囲内で冷却を実施し、その後、水量を大幅に増大して急冷によって冷却することで、遷移領域の期間を小さく若しくはゼロとして核沸騰領域での冷却にすることが出来る。この結果、薄板であっても、板厚変動の抑制及び冷却ムラの抑制を行いつつ先端・尾端部の不良部も抑制することが可能となる。   Furthermore, the first cooling device and the second cooling device are provided as the cooling devices, and the first cooling device performs cooling within the temperature range of the film boiling region, and then the water amount is greatly increased and cooled by rapid cooling. The period of the transition region can be reduced or reduced to zero to achieve cooling in the nucleate boiling region. As a result, even if it is a thin plate, it is possible to suppress defective portions at the tip and tail ends while suppressing variation in thickness and cooling unevenness.

このように、薄板であっても、歩留まりを減らしつつ高精度で冷却制御を実施することが可能となる。   Thus, even with a thin plate, it is possible to perform cooling control with high accuracy while reducing the yield.

本発明に基づく実施形態に係る連続熱間圧延設備の模式図である。It is a schematic diagram of the continuous hot rolling facility which concerns on embodiment based on this invention. 斜方ラミナー型の急冷冷却設備を説明する模式図である。It is a schematic diagram explaining an oblique laminar type rapid cooling equipment. 各コイル(鋼帯)を接合しないで冷却処理をした場合の巻取り温度を説明する図である。It is a figure explaining winding temperature at the time of cooling processing, without joining each coil (steel strip). 各コイル(鋼帯)を順次接合して冷却処理をした場合の巻取り温度を説明する図である。It is a figure explaining coiling | winding temperature at the time of joining and cooling each coil (steel strip) sequentially. 本発明を適用した場合の板厚及び温度を示す図である。It is a figure which shows plate | board thickness and temperature at the time of applying this invention. 比較例の場合の板厚及び温度を示す図である。It is a figure which shows the plate | board thickness and temperature in the case of a comparative example.

次に、本発明の実施形態について図面を参照しつつ説明する。
図1は、本発明に基づく実施形態の連続熱間圧延設備を説明する模式図である。
本実施形態の連続熱間圧延設備は、図1に示すように、上流側から下流側に向けて、加熱炉1、粗圧延機2、シートバーコイラ3、接合装置4、高周波誘導加熱装置5、仕上圧延機6、ランナウトテーブル11、巻取り装置12が順に配置されている。
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a continuous hot rolling facility according to an embodiment of the present invention.
As shown in FIG. 1, the continuous hot rolling facility of the present embodiment has a heating furnace 1, a rough rolling mill 2, a sheet bar coiler 3, a joining device 4, and a high frequency induction heating device 5 from the upstream side toward the downstream side. The finish rolling mill 6, the run-out table 11, and the winding device 12 are arranged in this order.

上記ランナウトテーブル11に沿って、上流側の第1冷却装置7と、下流側の第2冷却装置8が設けられ、これら2つの冷却装置7,8によって、ランナウトテーブル11上を通板している間に鋼帯9の冷却が実施される。本実施形態では、第1冷却装置7が円管ラミナー設備7で構成され、第2冷却装置8が斜方ラミナー型の急冷冷却設備8で構成される場合で説明する。   A first cooling device 7 on the upstream side and a second cooling device 8 on the downstream side are provided along the runout table 11, and the two cooling devices 7 and 8 pass through the runout table 11. In the meantime, the steel strip 9 is cooled. In the present embodiment, a case will be described in which the first cooling device 7 is configured by a circular laminar facility 7 and the second cooling device 8 is configured by an oblique laminar type rapid cooling facility 8.

加熱炉1は、スラブを予め設定したスラブ温度まで加熱する。
粗圧延機2は、加熱されたスラブを予め設定した板厚まで粗圧延する。
シートバーコイラ3は、粗圧延によって形成されたシートバー(鋼帯9)を巻取り・巻戻し処理を行う。
接合装置4は、先行材の尾端部と後行材の先端部を順次、突合せ溶接して接合する。これによってコイルが連続して仕上圧延機及び冷却装置に搬送されることとなる。
The heating furnace 1 heats the slab to a preset slab temperature.
The rough rolling machine 2 roughly rolls the heated slab to a preset plate thickness.
The sheet bar coiler 3 winds and unwinds a sheet bar (steel strip 9) formed by rough rolling.
The joining device 4 joins the tail end portion of the preceding material and the tip end portion of the succeeding material sequentially by butt welding. As a result, the coil is continuously conveyed to the finishing mill and the cooling device.

高周波誘導加熱装置5は、上記接合装置4で接合されることで、連続した鋼帯9の両端部を除く長手方向中央部(定常部)の温度が、仕上圧延出側温度で目標温度範囲内となると推定される温度まで加熱する。なお、搬送速度などによって仕上圧延出側温度で予め設
定した温度となる仕上入側での温度を求めることが出来る。なお、高周波誘導加熱装置5は、接合後かつ仕上圧延前にシートバーを巻き取りした際の最外巻きおよび最内巻きを含む部分を幅全体にわたり加熱する。
The high frequency induction heating device 5 is joined by the joining device 4 so that the temperature in the longitudinal center (steady portion) excluding both ends of the continuous steel strip 9 is within the target temperature range at the finish rolling exit temperature. Heat to the estimated temperature. In addition, the temperature at the finishing input which becomes the temperature preset at the finishing rolling exit temperature can be obtained by the conveying speed or the like. The high-frequency induction heating device 5 heats a portion including the outermost winding and the innermost winding when the sheet bar is wound up after joining and before finish rolling over the entire width.

仕上圧延機6は、1.8mm以下の目標とする板厚まで仕上圧延する。
円管ラミナー設備7は、水流密度が350L/(分・m)以上1200L/(分・m)以下の冷却水をノズルから噴射することで、搬送される鋼帯9を、円管ラミナー設備7出側での鋼帯表面温度が500℃となるように冷却を実施する。冷却制御は、仕上圧延機6出側の温度と鋼板温度とに基づき冷却量を調整することで実施する。
The finish rolling mill 6 finish-rolls to a target plate thickness of 1.8 mm or less.
Circular tube laminar facility 7, by water flow density injects 350L / (min · m 2) or more 1200L / (min · m 2) or less of the cooling water from the nozzle, the steel strip 9 being conveyed, circular tube laminar Cooling is performed so that the steel strip surface temperature on the exit side of the facility 7 is 500 ° C. The cooling control is performed by adjusting the cooling amount based on the temperature on the exit side of the finishing mill 6 and the steel plate temperature.

急冷冷却設備8は、水流密度が2000L/(分・m)以上の冷却水をノズルから噴射することで、搬送される鋼帯9を、鋼帯表面温度が450℃以下となるように冷却を実施する。
この急冷冷却設備8は、図2に示すように、鋼帯9の搬送方向に間隔を開けて対を為すノズル10群を配置されている。各ノズル10群は、噴射軸が、垂直方向に対して対を為すノズル群側に傾斜角θだけ傾いて設定されている。傾斜角θは、例えば30度〜60度、好ましくは30度〜50度の範囲に設定する。但し、対向するノズル10群からの噴射水流が交差しないように配置する。
The rapid cooling equipment 8 cools the steel strip 9 to be conveyed so that the steel strip surface temperature is 450 ° C. or less by injecting cooling water having a water flow density of 2000 L / (min · m 2 ) or more from the nozzle. To implement.
As shown in FIG. 2, the rapid cooling equipment 8 is provided with a group of nozzles 10 that are paired with an interval in the conveying direction of the steel strip 9. Each group of nozzles 10 is set such that the injection axis is inclined by an inclination angle θ toward the nozzle group that forms a pair with respect to the vertical direction. The inclination angle θ is set in the range of, for example, 30 degrees to 60 degrees, preferably 30 degrees to 50 degrees. However, it arrange | positions so that the jet water flow from the nozzle 10 group which opposes may not cross | intersect.

これによって、対を為す各ノズル10群から噴射された冷却水は、鋼板搬送方向に傾いた斜め方向から鋼帯表面に衝突した後に、他のノズル群10側に向けて移動する。この結果、対を為す各ノズル10群から噴射された冷却水はそれぞれ、鋼帯表面に衝突した後に互いに鋼帯表面上において鋼板搬送方向で衝突し、その衝突によって鋼帯幅方向に排出される。これによって鋼帯表面上への滞留水が無くなるか大幅に減少する。
なお、円管ラミナー設備7や急冷冷却設備8の各ノズルから噴射される冷却水の形状は、ラミナ状でもジェット流でも構わない。上記水流密度が確保可能であれば特に限定はない。
Thus, the cooling water sprayed from each pair of nozzles 10 is moved toward the other nozzle group 10 after colliding with the steel strip surface from an oblique direction inclined in the steel plate conveyance direction. As a result, the cooling water sprayed from each of the paired nozzles 10 collides with the steel strip surface and then collides with each other in the steel plate conveying direction on the steel strip surface, and is discharged in the steel strip width direction by the collision. . This eliminates or significantly reduces the water remaining on the steel strip surface.
In addition, the shape of the cooling water injected from each nozzle of the circular tube laminar equipment 7 or the rapid cooling cooling equipment 8 may be laminar or jet flow. There is no particular limitation as long as the water flow density can be secured.

(動作その他)
加熱炉1内で所定温度に加熱したスラブを粗圧延機2で粗圧延し、粗圧延によって形成されたシートバーをシートバーコイラ3で巻き取り、シートバーコイラ3から巻き戻したシートバーである後行材の先端部を先行材の尾端部に接合装置4で接合する。続いて、接合後かつ仕上圧延前にシートバーを巻き取りした際の最外巻きおよび最内巻きを含む部分を幅全体にわたり5の高周波誘導加熱装置5により加熱することで、コイル全長にわたり、仕上出側温度を目標の温度範囲内として仕上圧延機6で連続的に仕上圧延する。
(Operation other)
This is a sheet bar obtained by roughly rolling a slab heated to a predetermined temperature in a heating furnace 1 with a roughing mill 2, winding a sheet bar formed by the rough rolling with a sheet bar coiler 3, and rewinding from the sheet bar coiler 3. The leading end portion of the succeeding material is joined to the tail end portion of the preceding material by the joining device 4. Subsequently, the portion including the outermost winding and the innermost winding when the sheet bar is wound up after joining and finish rolling is heated by the high frequency induction heating device 5 over the entire width, thereby finishing the entire length of the coil. Finishing rolling is continuously performed by the finishing mill 6 with the delivery temperature within the target temperature range.

以上の設備構成によって、板厚変動を抑制しつつランナウトテーブル11上での安定した通板性を、2コイル目以降に関して確保することができる。
その後、円管ラミナー設備7を用いて膜沸騰領域の下限値若しくは下限値近傍となる500℃まで冷却を行い、続いて斜方ラミナー型の急速冷却設備を用いて450℃以下まで急速冷却を行う。
With the above equipment configuration, stable plate-passability on the run-out table 11 can be ensured for the second and subsequent coils while suppressing fluctuations in plate thickness.
Thereafter, the tube laminar equipment 7 is used to cool to 500 ° C., which is the lower limit value of the film boiling region or near the lower limit value, and then the oblique laminar type rapid cooling equipment is used to rapidly cool to 450 ° C. or less. .

通常のランナウト冷却では約500℃を境に遷移沸騰が開始して温度の低下とともに熱流束が大きくなる。このとき、本実施形態では、伝熱特性としては冷却水量を多くして遷移沸騰開始温度および核沸騰を維持する温度を高くする。このように、鋼帯温度が約500℃までは、円管ラミナー設備7によって通常のランナウト冷却を実施して、それ以下の温度領域では冷却水量を多くしてすべて核沸騰領域で冷却するように制御すれば、冷却装置内において遷移沸騰は発生しないが小さい期間だけとなり、冷却後の温度偏差の発生や冷却停止温度の精度低下を抑制することが可能となる。   In normal run-out cooling, transition boiling starts at about 500 ° C., and the heat flux increases as the temperature decreases. At this time, in the present embodiment, as the heat transfer characteristics, the amount of cooling water is increased, and the transition boiling start temperature and the temperature for maintaining nucleate boiling are increased. In this way, when the steel strip temperature is up to about 500 ° C., normal run-out cooling is performed by the circular tube laminar equipment 7, and the cooling water amount is increased in the temperature range below that to cool all in the nucleate boiling region. If controlled, transition boiling does not occur in the cooling device, but only during a small period, and it is possible to suppress the occurrence of temperature deviation after cooling and the decrease in accuracy of the cooling stop temperature.

すなわち、第1冷却装置7は既存のランナウト冷却装置を利用して500℃程度まで冷却し、第2冷却装置8では、核沸騰を確実に実施する水量密度2000L/(min.m)で急速冷却をすることで、遷移沸騰領域を回避するようにして冷却が可能となる。
また第2冷却装置である急冷冷却設備8では、スリットや円管などからノズルから噴射されるラミナー若しくはジェット流などの噴射水流を対向して斜方ラミナー型とすることで、鋼板搬送方向で対を為す冷却水流の鋼帯表面上での衝突によって、冷却水が鋼帯9の幅方向に流れるように排出されて、冷却位置で鋼帯表面から滞留水が除去される。この結果、水切り装置も必要とせず、冷却と水切りを兼ねることが可能となる。
That is, the first cooling device 7 is cooled to about 500 ° C. using an existing run-out cooling device, and the second cooling device 8 is rapidly used at a water density of 2000 L / (min.m 2 ) for reliably performing nucleate boiling. By cooling, it becomes possible to cool so as to avoid the transition boiling region.
Further, in the quenching cooling equipment 8 as the second cooling device, a laminar or jet water flow such as a jet flow ejected from a nozzle through a slit or a circular pipe is opposed to form an oblique laminar type so that it can be opposed in the direction of conveying the steel plate. Due to the collision of the cooling water flow on the steel strip surface, the cooling water is discharged so as to flow in the width direction of the steel strip 9, and the stagnant water is removed from the steel strip surface at the cooling position. As a result, a draining device is not required, and both cooling and draining can be performed.

ここで、シートバーのコイルを接合しない場合には、図3に示すように、各コイルの先端部及び尾端部に不良部が発生する。また、このようにコイル毎に熱間圧延処理を行う制御方法にあっては、従来、板厚が1.8mm以下のような薄板の場合、先端・尾端部の通板性安定の観点から温度目標を上げて制御する。
一方、本実施形態では、図4に示すように、1コイル目の先端は、従来と同じ温度目標であるが、1コイル目の尾端からは温度目標を一定に保つことができる。なお、最終材の尾端部は、温度目標を上げて通板する。
Here, when the coil of the sheet bar is not joined, as shown in FIG. 3, defective portions are generated at the front end portion and the tail end portion of each coil. In addition, in the control method for performing the hot rolling process for each coil as described above, conventionally, in the case of a thin plate having a plate thickness of 1.8 mm or less, from the viewpoint of stability of the plate passing properties of the tip and tail ends. Increase the temperature target and control.
On the other hand, in this embodiment, as shown in FIG. 4, the tip of the first coil has the same temperature target as the conventional one, but the temperature target can be kept constant from the tail end of the first coil. It should be noted that the tail end of the final material is passed through with the temperature target raised.

これにより、本実施形態においては、連続圧延によって先端・尾端部の非定常部を少なくすることができる。例えば、従来2コイルの材料を作る場合、先端・尾端の非定常部は4回発生する。しかし、連続圧延を用いることで、2回に抑制することが可能である。この実施形態の方法を用いることで、先端・尾端部の非定常部を抑制し従来のような先端・尾端部における目標温度上昇を行う回数を削減できる。また、通板速度の加減速が少なくすることが出来る結果、冷却を行うランナウトテーブル11上で安定的な通板が可能とある。このことからも不良部の抑制を行うことが可能である。   Thereby, in this embodiment, the unsteady part of a front-end | tip end can be decreased by continuous rolling. For example, when making a conventional 2-coil material, the unsteady portion at the tip and tail ends occurs four times. However, it is possible to suppress to twice by using continuous rolling. By using the method of this embodiment, it is possible to suppress the unsteady portion of the tip / tail end portion and reduce the number of times of performing the target temperature increase at the tip / tail end portion as in the prior art. Moreover, as a result of reducing acceleration / deceleration of the plate passing speed, stable plate passing is possible on the run-out table 11 that performs cooling. This also makes it possible to suppress defective portions.

以上のように、本実施形態では、板厚1.8mm以下の薄板鋼帯9であって450℃以下の巻取り温度に設定した場合でも、板厚変動、冷却ムラを抑制しつつ安定的に薄物熱延鋼帯9の製造が可能であり、また非定常部を少なくすることができるので不良部の抑制が期待できる。
ここで、本発明は、板厚1.8mm以下の薄板であって、特に、温度敏感性が高い鋼板の製造に好適である。例えば、ハイテン材など引張強度(TS)が390MPa以上の鋼板に好適である。
As described above, in the present embodiment, even when the sheet steel strip 9 has a plate thickness of 1.8 mm or less and is set to a winding temperature of 450 ° C. or less, the plate thickness variation and cooling unevenness are suppressed stably. Since the thin hot-rolled steel strip 9 can be manufactured and the number of unsteady portions can be reduced, it can be expected that defective portions are suppressed.
Here, the present invention is suitable for the production of a steel plate having a thickness of 1.8 mm or less and having particularly high temperature sensitivity. For example, it is suitable for a steel plate having a tensile strength (TS) of 390 MPa or more, such as a high-tensile material.

その理由は、次の通りである。
引張強度(TS)が390MPa以上の鋼板では、巻取り温度が500℃よりも低い温度となると、ベイナイト組織が出てきて低温ほど急激に高強度化する。なお、400℃よりも低くなるとマルテンサイト組織が出来てくる。このように、本発明の巻取り温度である450℃を含む、400℃〜500℃の巻取り温度範囲においては、引張強度(TS)が390MPa以上の鋼板がベイナイト組織の領域となる。
The reason is as follows.
In a steel sheet having a tensile strength (TS) of 390 MPa or more, when the coiling temperature is lower than 500 ° C., a bainite structure appears and the strength is rapidly increased as the temperature decreases. When the temperature is lower than 400 ° C., a martensite structure is formed. Thus, in the coiling temperature range of 400 ° C. to 500 ° C. including the coiling temperature of 450 ° C. of the present invention, the steel sheet having a tensile strength (TS) of 390 MPa or more becomes the bainite structure region.

上記のように、巻取り温度が500℃未満では、低温ほど急激に高強度化する、つまり少しの温度変動が強度変動に直結するため、本願発明のように温度変動を抑える事が可能な技術を採用することで、より目標とする鋼板の製造が可能となる。
なお、巻取り温度を上記ベイナイト組織の領域に制御することで、穴拡げ性を、パーライト組織やマルテンサイト組織の領域に制御する場合に比べて高くすることが出来る。
As described above, when the coiling temperature is less than 500 ° C., the strength rapidly increases as the temperature decreases, that is, a slight temperature fluctuation is directly connected to the strength fluctuation, and thus a technique capable of suppressing the temperature fluctuation as in the present invention. By adopting, it becomes possible to produce a more targeted steel sheet.
In addition, by controlling the coiling temperature in the region of the bainite structure, the hole expandability can be increased as compared with the case of controlling in the region of the pearlite structure or the martensite structure.

なお、板厚1.8mm以下の薄板鋼帯9を製造する際に、上記第1冷却装置7若しくは第2冷却装置8のいずれかだけで冷却を実施した場合には、先端部及び尾端部を除く定常部においても巻取り温度がハンチングを起こしやすくなり。特に500℃以下の巻取り温度に設定した場合に上記ハンチングは顕著となる。この場合には、歩留まりが低くなる。   In addition, when manufacturing the thin steel strip 9 having a thickness of 1.8 mm or less, when cooling is performed only by the first cooling device 7 or the second cooling device 8, the tip end portion and the tail end portion The coiling temperature is likely to cause hunting even in the stationary part except for. In particular, the hunting becomes noticeable when the coiling temperature is set to 500 ° C. or lower. In this case, the yield is lowered.

次に、本発明の実施例に関して熱延鋼帯9の製造について説明する。
厚み260mmのスラブを加熱炉1で1200℃まで加熱した後、粗圧延機2により28mmまで圧延し、さらに仕上圧延機6により1.6mmまで圧延した。
図5に連続圧延を行い、円管ラミナーと斜方ラミナー型の急速冷却設備を使用した場合の仕上圧延機6出側板厚、及び巻取り時の温度の各履歴(2コイル接合時)を示す。またそれぞれの比較例として図6に従来圧延方法で、円管ラミナーのみで冷却時の出側板厚の履歴、温度の履歴を示す。
Next, the production of the hot-rolled steel strip 9 will be described with respect to the embodiment of the present invention.
A slab having a thickness of 260 mm was heated to 1200 ° C. in the heating furnace 1, then rolled to 28 mm by the roughing mill 2, and further rolled to 1.6 mm by the finishing mill 6.
FIG. 5 shows the finish rolling mill 6 outlet side plate thickness and temperature history at the time of winding (when two coils are joined) when continuous rolling is performed and a circular tube laminar and oblique laminar type rapid cooling equipment is used. . Moreover, as a comparative example, FIG. 6 shows the history of the outlet side plate thickness and the temperature history during cooling using only the circular tube laminator by the conventional rolling method.

この図5から分かるように、本発明を適用した場合には、板厚・温度ともに従来材と比較して、良好であり、バラつきも低減でき、先端・尾端部の切捨てが少ないのが明確である。
一方、図6の比較材の場合には、先端・尾端部の板厚、温度偏差が大きく発明材と比較して不良部が多くなるのが明確である。
As can be seen from FIG. 5, when the present invention is applied, both the thickness and temperature are better than the conventional material, the variation can be reduced, and the tip and tail ends are cut off less clearly. It is.
On the other hand, in the case of the comparative material of FIG. 6, it is clear that the thickness and temperature deviation of the tip and tail ends are large and the number of defective parts increases as compared with the inventive material.

このように本発明を適用することで、温度、板厚のバラつきを低減し先端・尾端部の不良部も低下できることが分かった。   Thus, it has been found that application of the present invention can reduce variations in temperature and plate thickness and can also reduce defective portions at the tip and tail ends.

1 加熱炉
2 粗圧延機
3 シートバーコイラ
4 接合装置
5 高周波誘導加熱装置
6 仕上圧延機
7 第1冷却装置(円管ラミナー設備)
8 第2冷却装置(急冷冷却設備)
9 鋼帯
10 ノズル(第2冷却装置)
11 ランナウトテーブル
12 巻取り装置
DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Coarse rolling mill 3 Sheet bar coiler 4 Joining device 5 High frequency induction heating device 6 Finishing rolling mill 7 1st cooling device (circular tube laminar equipment)
8 Second cooling device (rapid cooling equipment)
9 Steel strip 10 Nozzle (second cooling device)
11 Runout Table 12 Winding Device

Claims (1)

仕上圧延後の鋼帯を巻取り・巻戻しするシートバーコイラと、
シートバーコイラから巻き戻された後行材の先端部と先行材の尾端部とを接合する接合装置と、
接合装置の下流に配置されて搬送されてくる鋼帯を加熱する加熱装置と、
加熱装置で加熱された鋼帯を板厚1.8mm以下に仕上圧延を行う仕上圧延機と、
仕上圧延機で圧延された鋼帯をランナウトテーブルで搬送中に冷却する冷却装置と、を備え、
上記冷却装置は、上流側の第1冷却装置と、下流側の第2冷却装置とを備え、
上記第1冷却装置は、水流密度が350L/(分・m)以上1200L/(分・m)以下の冷却水で、鋼帯表面温度を膜沸騰領域の温度範囲内で冷却を行い、
上記第2冷却装置は、水流密度が2000L/(分・m)以上の冷却水で、鋼帯表面温度を450℃以下に冷却することを特徴とする連続熱間圧延設備。
A sheet bar coiler that winds and unwinds the steel strip after finish rolling;
A joining device that joins the leading end of the succeeding material and the tail end of the preceding material unwound from the sheet bar coiler;
A heating device for heating the steel strip disposed and conveyed downstream of the joining device;
A finish rolling mill for performing finish rolling on the steel strip heated by the heating device to a thickness of 1.8 mm or less;
A cooling device that cools the steel strip rolled by the finish rolling mill during conveyance by the run-out table,
The cooling device includes an upstream first cooling device and a downstream second cooling device,
The first cooling device, water flow density of 350L / (min · m 2) or more 1200L / (min · m 2) or less of the cooling water, cooling the steel strip surface temperature within a temperature range of film boiling region,
The second cooling device is a continuous hot rolling facility characterized by cooling the steel strip surface temperature to 450 ° C. or less with cooling water having a water flow density of 2000 L / (min · m 2 ) or more.
JP2012115372A 2012-05-21 2012-05-21 Steel strip production method using continuous hot rolling equipment Active JP5991023B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2012115372A JP5991023B2 (en) 2012-05-21 2012-05-21 Steel strip production method using continuous hot rolling equipment

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2012115372A JP5991023B2 (en) 2012-05-21 2012-05-21 Steel strip production method using continuous hot rolling equipment

Publications (2)

Publication Number Publication Date
JP2013240808A true JP2013240808A (en) 2013-12-05
JP5991023B2 JP5991023B2 (en) 2016-09-14

Family

ID=49842231

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2012115372A Active JP5991023B2 (en) 2012-05-21 2012-05-21 Steel strip production method using continuous hot rolling equipment

Country Status (1)

Country Link
JP (1) JP5991023B2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10557666B2 (en) 2017-06-19 2020-02-11 Chugai Ro Co., Ltd. Cooling apparatus for metal strip
JP2021107566A (en) * 2019-12-27 2021-07-29 中外炉工業株式会社 Cooling device for metal strip

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006239777A (en) * 1997-10-07 2006-09-14 Jfe Steel Kk Method for manufacturing hot-rolled steel sheet
JP2008110353A (en) * 2006-10-30 2008-05-15 Jfe Steel Kk Method of cooling hot-rolled steel strip

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006239777A (en) * 1997-10-07 2006-09-14 Jfe Steel Kk Method for manufacturing hot-rolled steel sheet
JP2008110353A (en) * 2006-10-30 2008-05-15 Jfe Steel Kk Method of cooling hot-rolled steel strip

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10557666B2 (en) 2017-06-19 2020-02-11 Chugai Ro Co., Ltd. Cooling apparatus for metal strip
JP2021107566A (en) * 2019-12-27 2021-07-29 中外炉工業株式会社 Cooling device for metal strip

Also Published As

Publication number Publication date
JP5991023B2 (en) 2016-09-14

Similar Documents

Publication Publication Date Title
JP4029871B2 (en) Steel plate cooling device, hot-rolled steel plate manufacturing apparatus and manufacturing method
JP4586791B2 (en) Cooling method for hot-rolled steel strip
JP4678069B1 (en) Hot rolled steel sheet cooling device
JP5573837B2 (en) Hot rolled steel sheet cooling apparatus, cooling method, manufacturing apparatus, and manufacturing method
JP3642031B2 (en) Hot strip strip cooling system
JP5577655B2 (en) Hot-rolled steel sheet cooling equipment and cooling method
JP5673530B2 (en) Hot rolled steel sheet cooling apparatus, cooling method, manufacturing apparatus, and manufacturing method
JP5310966B1 (en) Hot-rolled steel sheet cooling device
JP5991023B2 (en) Steel strip production method using continuous hot rolling equipment
JP4029865B2 (en) Hot rolled steel sheet manufacturing equipment and hot rolled steel sheet manufacturing method
JP3562423B2 (en) Cooling apparatus for hot-rolled steel strip and cooling method
JP4120129B2 (en) Hot-rolled steel strip cooling device and cooling method thereof
JP3644434B2 (en) Hot rolled steel strip manufacturing equipment and hot rolled steel strip manufacturing method
JP3642024B2 (en) Hot rolling equipment and rolling method for hot rolled steel strip
JP2009279629A (en) Apparatus and method for manufacturing hot-rolled steel sheet
JP2007038299A (en) Apparatus and method for cooling hot-rolled steel strip and method for manufacturing hot-rolled steel strip
JP5609407B2 (en) Manufacturing method and manufacturing equipment for hot-rolled steel sheet
JP3911952B2 (en) Method for producing ultra-low carbon hot-rolled steel strip
JP5663848B2 (en) Hot-rolled steel sheet cooling device and operation control method thereof
JP2006021246A (en) Equipment for manufacturing high-strength hot-rolled steel sheet
JP5609703B2 (en) Manufacturing method of hot-rolled steel sheet
JP4292672B2 (en) Hot-rolled steel strip cooling device and cooling method thereof
JP4924579B2 (en) Hot-rolled steel strip cooling device and cooling method thereof
JP4164982B2 (en) Hot-rolled steel strip cooling device and cooling method thereof
JP6233614B2 (en) Production line for hot-rolled steel strip and method for producing hot-rolled steel strip

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20150223

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20160224

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20160301

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20160408

A02 Decision of refusal

Free format text: JAPANESE INTERMEDIATE CODE: A02

Effective date: 20160517

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20160613

A911 Transfer to examiner for re-examination before appeal (zenchi)

Free format text: JAPANESE INTERMEDIATE CODE: A911

Effective date: 20160623

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20160719

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20160801

R150 Certificate of patent or registration of utility model

Ref document number: 5991023

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250