JP2005120409A - Method for manufacturing high-strength steel plate superior in uniformity of material in longitudinal direction of steel sheet - Google Patents
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 126
- 239000010959 steel Substances 0.000 title claims abstract description 126
- 239000000463 material Substances 0.000 title claims abstract description 83
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 title abstract description 29
- 238000010438 heat treatment Methods 0.000 claims abstract description 132
- 230000006698 induction Effects 0.000 claims abstract description 85
- 238000005496 tempering Methods 0.000 claims abstract description 18
- 238000005096 rolling process Methods 0.000 claims abstract description 15
- 238000001816 cooling Methods 0.000 claims description 15
- 238000005098 hot rolling Methods 0.000 claims description 8
- 238000010791 quenching Methods 0.000 claims description 7
- 230000000171 quenching effect Effects 0.000 claims description 7
- 238000004364 calculation method Methods 0.000 abstract description 11
- 238000004458 analytical method Methods 0.000 abstract description 3
- 238000009826 distribution Methods 0.000 description 6
- 238000012937 correction Methods 0.000 description 3
- 238000013178 mathematical model Methods 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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Abstract
Description
この発明は、熱間圧延後、加速冷却又は直接焼入れした後、圧延ライン上に設置した誘導加熱装置を用いてライン上で焼戻し処理を行う高強度鋼板の製造方法に関する。 The present invention relates to a method for manufacturing a high-strength steel sheet that is tempered on a line using an induction heating device installed on the rolling line after hot rolling, accelerated cooling or direct quenching.
最近、パイプラインや建築、橋梁等の鋼構造物において、高強度鋼の使用が増加している。一方、これらの用途における高精度設計により、材料特性のバラツキの小さい鋼板の要求が高まっている。特に、鋼板長手方向における強度のバラツキを一定レンジの範囲とする狭強度レンジの高強度鋼板が要求されるようになってきている。 Recently, the use of high-strength steel is increasing in steel structures such as pipelines, buildings and bridges. On the other hand, due to the high-precision design in these applications, there is an increasing demand for steel plates with small variations in material properties. In particular, a high-strength steel sheet having a narrow strength range in which the variation in strength in the longitudinal direction of the steel sheet is within a certain range has been required.
一般に高強度鋼板は、制御圧延や圧延後の加速冷却により製造される。制御圧延においては、オーステナイト未再結晶温度域や２相域で強圧下されるため、鋼板長手方向での温度のバラツキによる再結晶率や相分率の違いにより、強度の不均一を生じやすい。また、圧延後の加速冷却によっても、鋼板長手方向での冷却開始温度、冷却停止温度のバラツキにより強度の不均一が発生する。 In general, high-strength steel sheets are manufactured by controlled rolling or accelerated cooling after rolling. In controlled rolling, the austenite is not strongly recrystallized in the non-recrystallization temperature region or in the two-phase region, and therefore strength non-uniformity is likely to occur due to the difference in recrystallization rate and phase fraction due to temperature variation in the steel plate longitudinal direction. Further, even with accelerated cooling after rolling, non-uniformity in strength occurs due to variations in the cooling start temperature and cooling stop temperature in the longitudinal direction of the steel sheet.
これらのバラツキを低減するための対策として、鋼板をガス燃焼炉に挿入して均一な温度に加熱する焼戻し処理が行われてきた。この方法は、一般に焼き戻し前の強度が高い部分の方が焼戻しによる軟化量が大きいので、焼戻し後の強度の差が縮まることを利用している。しかしながら、従来の焼戻し処理の場合、軟化させる必要のない部分まで軟化するため強度のバラツキ低減には限度があるとともに、場合によっては規格強度を下回ってしまう恐れもある。さらに、オフラインでの熱処理のため、生産効率が悪いという問題があった。 As a countermeasure for reducing these variations, a tempering process in which a steel plate is inserted into a gas combustion furnace and heated to a uniform temperature has been performed. This method uses the fact that the difference in strength after tempering is reduced because the amount of softening due to tempering is generally greater in the portion having higher strength before tempering. However, in the case of the conventional tempering process, since the softening is performed up to a portion that does not need to be softened, there is a limit in reducing the variation in strength, and in some cases, the strength may be lower than the standard strength. Furthermore, there is a problem that the production efficiency is poor due to the offline heat treatment.
特許文献１(特開2003-27136号公報)には、誘導加熱装置により焼戻し処理を行い、鋼板の材料特性のバラツキを低減する方法が記載されている。これは、鋼板長手方向で加熱条件を変化させて誘導加熱することで、鋼板長手方向の強度を均一化するものである。
特許文献１(特開2003-27136号公報)記載の誘導加熱による焼戻しは、鋼板の先端部や尾端部のみの焼分けも可能なことから、鋼板長手方向の材料特性を均一化するには有効な手段である。また誘導加熱装置を圧延ライン上に設置して、オンラインで焼戻し処理することで生産効率の飛躍的な向上も期待できる。 The tempering by induction heating described in Patent Document 1 (Japanese Patent Laid-Open No. 2003-27136) is capable of tempering only the tip and tail ends of the steel plate, so that the material properties in the longitudinal direction of the steel plate can be made uniform. It is an effective means. A dramatic improvement in production efficiency can also be expected by installing an induction heating device on the rolling line and performing tempering online.
しかしながら、誘導加熱装置を設置したライン上で鋼材を搬送しながら加熱する場合、鋼材の先端部と尾端部では最初の誘導加熱装置によって誘導加熱されるまでの待ち時間が異なるため、大気への熱放散によって鋼板の長手方向で温度勾配を生じる。図１は、誘導加熱装置に搬送される直前の鋼材の長手方向の温度分布を模式的に示したものである。このような温度勾配がある場合、加熱後に均一な温度になるように温度勾配に合わせて長手方向で加熱条件を変化させて焼戻し処理するためには、複雑な温度制御が必要となる。たとえば、鋼材の進行方向に分割された各部分の温度を測定し、その温度値を用いて誘導加熱装置の最適な加熱電力をその都度繰り返して、解析手法により計算することが考えられる。しかし、この計算方式では計算量が非常に多く、計算機への負荷が大きい。 However, when heating while conveying steel on the line where the induction heating device is installed, the waiting time until induction heating by the first induction heating device is different at the tip and tail of the steel, A temperature gradient is produced in the longitudinal direction of the steel sheet by heat dissipation. FIG. 1 schematically shows a temperature distribution in the longitudinal direction of a steel material immediately before being conveyed to the induction heating device. When such a temperature gradient is present, complicated temperature control is required in order to change the heating conditions in the longitudinal direction in accordance with the temperature gradient so as to obtain a uniform temperature after heating and to perform tempering treatment. For example, it is conceivable that the temperature of each part divided in the traveling direction of the steel material is measured, and the optimum heating power of the induction heating device is repeated each time using the temperature value and calculated by an analysis method. However, in this calculation method, the calculation amount is very large and the load on the computer is large.
本発明は上記問題点を解決するためになされたもので、熱間圧延後、加速冷却又は直接焼入れした後、圧延ライン上に複数台設置した誘導加熱装置を用いて焼戻し処理を行う厚鋼板の製造方法において、複雑な温度制御や繰り返し計算のような計算量が非常に多い解析手法を必要としない、鋼板長手方向の強度のバラツキを低減する製造方法を提供することを目的とする。
The present invention was made in order to solve the above-mentioned problems. After hot rolling, accelerated cooling or direct quenching, and then a thick steel plate that is tempered using an induction heating device installed on a rolling line. It is an object of the present invention to provide a manufacturing method that reduces variations in strength in the longitudinal direction of a steel sheet and does not require an analysis method that requires a large amount of calculation such as complicated temperature control and repeated calculation.
上記の課題は、次の発明により解決される。その発明は、熱間圧延後、加速冷却又は直接焼入れした後、圧延ライン上に複数台設置した誘導加熱装置を用いて焼戻し処理を行う高強度鋼板の製造方法において、初段の誘導加熱装置の入り側に設けられた温度検出器で前記鋼材の先頭部分の温度を実測し、それぞれの誘導加熱装置毎の目標加熱温度を算出して前記鋼材の先頭部分に供給する電力を決定する工程と、
前記鋼材の先頭より後の部分においては、前記温度検出器で検出された温度と先頭部分の温度差に応じてそれぞれの誘導加熱装置毎の目標加熱温度を補正して新たな目標加熱温度を算出し、先頭より後ろの部分に供給する新たな電力を決定する工程と、
前記鋼材の移動に合わせて、それぞれの誘導加熱装置に前記決定された電力を制御して供給する工程とを有することを特徴とする鋼板長手方向の材質均一性に優れた厚鋼板の製造方法である。
The above problems are solved by the following invention. The invention relates to a method of manufacturing a high-strength steel sheet that is subjected to tempering using an induction heating device installed on a rolling line after hot rolling, accelerated cooling or direct quenching, and the first stage induction heating device is included. Measure the temperature of the top part of the steel material with a temperature detector provided on the side, calculate the target heating temperature for each induction heating device and determine the power to be supplied to the top part of the steel material,
In the part after the head of the steel material, a new target heating temperature is calculated by correcting the target heating temperature for each induction heating device according to the temperature difference between the temperature detected by the temperature detector and the head part. And determining the new power to be supplied to the part behind the head,
In accordance with the movement of the steel material, there is a step of controlling and supplying the determined power to each induction heating device, and a method for producing a thick steel plate having excellent material uniformity in the longitudinal direction of the steel plate is there.
また別の発明としては、熱間圧延後、加速冷却又は直接焼入れした後、圧延ライン上に複数台設置した誘導加熱装置を用いて焼戻し処理を行う高強度鋼板の製造方法において、初段の誘導加熱装置の入り側に設けられた温度検出器で前記鋼材の先頭部分の温度を実測し、それぞれの誘導加熱装置毎の目標加熱温度を算出して前記鋼材の先頭部分に供給する電力を決定する工程と、
前記鋼材の先頭部分の実測温度から、前記鋼材の尾端部分の温度を推定し、それぞれの誘導加熱装置毎の目標加熱温度を補正して新たな目標加熱温度を算出し、前記鋼材の尾端部分に供給する電力を決定する工程と、
前記鋼材の先頭部分と尾端部分に挟まれた中間部分においては、前記先端部分の実測温度と尾端部分の推定温度と、長手方向中間部分の各々の実測温度とに基づいて、それぞれの誘導加熱装置毎の目標加熱温度を補正して新たな目標温度を算出し、前記中間部分に供給する新たな電力を決定する工程と、
前記鋼材の移動に合わせて、それぞれの誘導加熱装置に前記決定された電力を制御して供給する工程とを有することを特徴とする鋼板長手方向の材質均一性に優れた厚鋼板の製造方法である。
As another invention, in the manufacturing method of high-strength steel sheet, after the hot rolling, accelerated cooling or direct quenching, and then tempering using an induction heating device installed on the rolling line, the first stage induction heating The step of measuring the temperature of the leading portion of the steel material with a temperature detector provided on the entry side of the device, calculating the target heating temperature for each induction heating device, and determining the power supplied to the leading portion of the steel material When,
From the measured temperature of the top portion of the steel material, the temperature of the tail end portion of the steel material is estimated, a new target heating temperature is calculated by correcting the target heating temperature for each induction heating device, and the tail end of the steel material Determining the power supplied to the part;
In the intermediate portion sandwiched between the head portion and the tail end portion of the steel material, each induction is based on the measured temperature of the tip portion, the estimated temperature of the tail end portion, and the measured temperature of each of the longitudinal intermediate portions. Correcting a target heating temperature for each heating device to calculate a new target temperature, and determining a new power to be supplied to the intermediate portion;
In accordance with the movement of the steel material, there is a step of controlling and supplying the determined power to each induction heating device, and a method for producing a thick steel plate having excellent material uniformity in the longitudinal direction of the steel plate is there.
これらの発明において更に、各誘導加熱装置間に設置された温度検出器により誘導加熱後の鋼板の長手方向の温度を測定し、前記実測温度から次の誘導加熱装置の目標加熱温度を補正する工程と、
補正された目標加熱温度に基づき次の誘導加熱装置に供給する新たな電力を決定する工程とを有することを特徴とする鋼板長手方向の材質均一性に優れた厚鋼板の製造方法とすることもできる。
In these inventions, the step of measuring the longitudinal temperature of the steel sheet after induction heating by a temperature detector installed between the induction heating devices and correcting the target heating temperature of the next induction heating device from the measured temperature When,
And a method of determining a new electric power to be supplied to the next induction heating device based on the corrected target heating temperature. it can.
以上の発明は、熱間圧延後、加速冷却又は直接焼入れした後、圧延ライン上に複数台設置した誘導加熱装置を用いて焼戻し処理を行う厚鋼板の製造方法において、鋼板の長手方向の温度勾配に応じて誘導加熱装置への供給電力を制御することで、鋼板長手方向の強度のバラツキを低減するものである。いずれの発明においても、鋼材の先頭部分の温度を実測し、その実測値に基づきそれぞれの誘導加熱装置毎の目標加熱温度を算出し、各誘導加熱装置に供給する電力を制御することを特徴としている。
The above invention is a method for producing a thick steel plate, which is subjected to tempering using an induction heating device installed on a rolling line after hot rolling, accelerated cooling or direct quenching, and a temperature gradient in the longitudinal direction of the steel plate. By controlling the electric power supplied to the induction heating device according to the above, variation in strength in the longitudinal direction of the steel sheet is reduced. In any of the inventions, the temperature of the leading portion of the steel material is measured, the target heating temperature for each induction heating device is calculated based on the measured value, and the power supplied to each induction heating device is controlled. Yes.
本発明によれば、鋼板を加速冷却又は直接焼入れした後、圧延ライン上に複数台設置した誘導加熱装置を用いて焼戻し処理を行うことにより、鋼板長手方向での材質均一性に優れた高強度鋼板を製造することが可能となる。特に誘導加熱装置の設定電力値の計算を行う制御装置に過大な負荷をかけることなく、高精度の温度制御を行うことができる。
According to the present invention, the steel sheet is accelerated and cooled or directly quenched, and then subjected to a tempering process using an induction heating apparatus installed on a rolling line, thereby providing high strength with excellent material uniformity in the longitudinal direction of the steel sheet. A steel plate can be manufactured. In particular, high-precision temperature control can be performed without applying an excessive load to the control device that calculates the set power value of the induction heating device.
以下に、本発明を実施するための制御方法を詳細に説明する。 Below, the control method for implementing this invention is demonstrated in detail.
図２は、本発明の実施の形態に係る誘導加熱装置の概略構成の一例を示す側面図である。ライン上には誘導加熱装置１が複数台設置されており、被加熱材である鋼材２は図中左から右に搬送されながら、それぞれの誘導加熱装置１によって加熱される。
FIG. 2 is a side view showing an example of a schematic configuration of the induction heating apparatus according to the embodiment of the present invention. A plurality of
初段の誘導加熱装置１の入り側には温度検出器３が備えられ、加熱前の鋼材２の温度を検出する。検出された温度は制御装置４に入力され、制御装置４は鋼材２の温度からそれぞれの誘導加熱装置１に供給するべき電力量を計算し、電力供給装置５に対してその電力を設定値として出力する。そして、電力供給装置５は誘導加熱装置１の電力を制御装置４からの設定値となるよう制御する。
A
なお、制御装置４には搬送ローラ７から搬送パルスが入力され、制御装置４はこのパルス信号に基づいて、鋼材の搬送速度、搬送量を計算する。また、各誘導加熱装置の出側には温度検出器８が備えられ、加熱処理された鋼材２の温度を監視できるように構成されている。 The control device 4 receives a transport pulse from the transport roller 7, and the control device 4 calculates the transport speed and transport amount of the steel material based on the pulse signal. Moreover, the temperature detector 8 is provided in the exit side of each induction heating apparatus, and it is comprised so that the temperature of the heat-treated steel material 2 can be monitored.
次に、本構成の誘導加熱装置を用いて鋼材の温度を制御する方法について説明する。 Next, a method for controlling the temperature of the steel material using the induction heating apparatus of this configuration will be described.
本発明においては、鋼材の移動方向の温度を精度良く制御するため、鋼材を仮想的に複数の部分（以下、「仮想部分」という）に分割して温度を管理する。図２で鋼材に記された点線が仮想部分の境界を示している。この仮想部分に記載された番号ｉ−１，ｉ，ｉ＋１は、鋼材２の先頭からの順番を表したものである。 In the present invention, in order to accurately control the temperature in the moving direction of the steel material, the steel material is virtually divided into a plurality of parts (hereinafter referred to as “virtual parts”) to manage the temperature. The dotted lines marked on the steel material in FIG. 2 indicate the boundaries of the virtual part. The numbers i−1, i, i + 1 described in the virtual part represent the order from the top of the steel material 2.
誘導加熱装置を複数台用いて鋼材を加熱する場合、それぞれの誘導加熱装置での加熱目標温度は、最終目標温度、消費電力、鋼材の熱処理上受ける温度制約条件（たとえば、表面温度がＡｃ1変態温度以下）などの要因により決定される。通常これらの条件は、加熱処理のための基準として鋼材毎に予め上位コンピューター等から指示され、制御装置に入力されている。 When a steel material is heated using a plurality of induction heating devices, the heating target temperature in each induction heating device is a temperature restriction condition (for example, the surface temperature is Ac 1 transformation) that is subject to the final target temperature, power consumption, and heat treatment of the steel material. It is determined by factors such as temperature and below. Usually, these conditions are instructed in advance by a host computer or the like for each steel material as a standard for heat treatment, and are input to the control device.
[供給電力制御方法１]
まず、第1の実施形態により各誘導加熱装置に供給する電力を決定する手順を示す。
（Ｓ１）加熱する鋼材の最終目標温度を制御装置から取り出して決定する。
（Ｓ２）鋼材が搬送されて所定の位置を通過したときに、図示しない通過検出器が「材料有り」を検出して制御装置に信号を出力する。制御装置はこのタイミングで鋼材の先頭部分の温度と鋼材の搬送速度を読み込む。
（Ｓ３）伝熱計算等の手法によって、各誘導加熱装置での加熱目標温度を決定する。
（Ｓ４）ラインに設置される複数の誘導加熱装置のうち、先頭からｊ番目の誘導加熱装置の加熱目標温度をＴｔ(ｊ)とし、Ｔｔ(ｊ)を得るための電力量Ｐｔ(ｊ）を算出する。
（Ｓ５）鋼材の先頭部分の移動に同期して、算出した設定電力Ｐｔ(ｊ）を電力供給装置に出力する。
（Ｓ６）鋼材が搬送されて、鋼材の長手位置が変化していくのに合わせて、鋼材のｉ番目の仮想部分の温度を読み込む。
（Ｓ７）制御装置は実測温度から加熱目標温度Ｔｔ(ｊ)を補正し、先頭からｉ番目の仮想部分の新たな加熱目標温度Ｔｉ(ｊ)を算出する。
（Ｓ８）新たな加熱目標温度Ｔｉ(ｊ)から、誘導加熱装置ｊに供給する新たな電力Ｐｉ(ｊ)を算出する。
[Supply power control method 1]
First, a procedure for determining the electric power supplied to each induction heating device according to the first embodiment will be described.
(S1) The final target temperature of the steel material to be heated is taken out from the control device and determined.
(S2) When the steel material is transported and passes a predetermined position, a passage detector (not shown) detects “material present” and outputs a signal to the control device. At this timing, the control device reads the temperature of the top portion of the steel material and the conveyance speed of the steel material.
(S3) The heating target temperature in each induction heating device is determined by a method such as heat transfer calculation.
(S4) Of the plurality of induction heating devices installed in the line, the heating target temperature of the jth induction heating device from the top is Tt (j), and the electric energy Pt (j) for obtaining Tt (j) is calculate.
(S5) The calculated set power Pt (j) is output to the power supply device in synchronization with the movement of the leading portion of the steel material.
(S6) The temperature of the i-th imaginary part of the steel material is read as the steel material is conveyed and the longitudinal position of the steel material changes.
(S7) The control device corrects the heating target temperature Tt (j) from the actually measured temperature, and calculates a new heating target temperature Ti (j) for the i-th virtual part from the head.
(S8) New electric power Pi (j) supplied to the induction heating device j is calculated from the new heating target temperature Ti (j).
ここで、Ｐｉ(ｊ)は以下の式で表される。 Here, Pi (j) is expressed by the following equation.
Ｐｉ(ｊ)＝Ｐｔ(ｊ）＋ΔＰｉ
ΔＰｉは、ΔＴ＝Ｔｉ−Ｔｔの昇温量を与える電力
Ｐｔ：先頭部分電力、Ｐｉ：仮想部分ｉでの電力
Ｔｔ：先頭部分温度、Ｔｉ：仮想部分ｉの温度
（Ｓ９）鋼材のｉ番目の仮想部分の搬送に同期して、算定した電力Ｐｉ（ｊ）を電力供給装置に出力する。
Pi (j) = Pt (j) + ΔPi
ΔPi is power that gives a temperature increase amount of ΔT = Ti−Tt Pt: leading partial power, Pi: power at virtual portion i Tt: leading portion temperature, Ti: temperature of virtual portion i (S9) i-th of steel material The calculated power Pi (j) is output to the power supply apparatus in synchronization with the transport of the virtual part.
このようにして、初期温度差ΔＴの影響を、加熱目標温度を変更して、全ての誘導加熱装置を使用して解消することによって鋼材の均一加熱が可能になるとともに、誘導加熱装置の負荷軽減を図ることが出来る。 In this way, the effect of the initial temperature difference ΔT can be eliminated by changing the heating target temperature and using all induction heating devices, and the steel material can be uniformly heated, and the load on the induction heating device can be reduced. Can be planned.
[供給電力制御方法２]
次に、第２の実施形態により各誘導加熱装置に供給する電力を決定する手順を示す。
（Ｓ１）加熱する鋼材の最終目標温度を制御装置から取り出して決定する。
（Ｓ２）鋼材が搬送されて所定の位置を通過したときに、図示しない通過検出器が「材料有り」を検出して制御装置に信号を出力する。制御装置はこのタイミングで鋼材の先頭部分の温度と鋼材の搬送速度を読み込む。
（Ｓ３）先頭部分の温度から尾端部分の温度を推定する。尾端部分の温度推定方法は、同じ時刻であれば冷却後の先頭部と尾端部の温度が同じものであるとして、同じ位置、すなわち誘導加熱装置に入るまでの先頭部と尾端部の時間差から冷却されて温度降下がどれくらいかを推定する。なお、より精度を上げるためには、過去に同じ条件の鋼材の先頭部と尾端部の温度差を記憶しておき、その値に基づいて尾端部の温度を推定することも可能である。
（Ｓ４）伝熱計算等の手法によって、先頭部分と尾端部分について最終目標温度を得るためのそれぞれの誘導加熱装置での加熱目標温度を決定する。
（Ｓ５）ラインに設置される複数の誘導加熱装置のうち、先頭からｊ番目の誘導加熱装置の先頭部分の加熱目標温度をＴｔ(ｊ)、尾端部分の加熱目標温度をＴｂ(ｊ)とし、Ｔｔ(ｊ)、Ｔｂ(ｊ)を得るための電力量Ｐｔ(ｊ)、Ｐｂ(ｊ)を算出する。
（Ｓ６）鋼材の先頭部分の移動に同期して、算出した設定電力Ｐｔ(ｊ）を電力供給装置に出力する。
（Ｓ７）鋼材が搬送されて、鋼材の長手位置が変化していくのに合わせて、鋼材のｉ番目の仮想部分の温度を読み込む。
（Ｓ８）制御装置は実測温度から加熱目標温度Ｔｔ(ｊ)を補正し、先頭からｉ番目の仮想部分の新たな加熱目標温度Ｔｉ(ｊ)を算出する。
（Ｓ９）新たな加熱目標温度Ｔｉ(ｊ)から、誘導加熱装置ｊに供給する新たな電力Ｐｉ(ｊ）を算出する。
[Supply power control method 2]
Next, a procedure for determining the power supplied to each induction heating device according to the second embodiment will be described.
(S1) The final target temperature of the steel material to be heated is taken out from the control device and determined.
(S2) When the steel material is transported and passes a predetermined position, a passage detector (not shown) detects “material present” and outputs a signal to the control device. At this timing, the control device reads the temperature of the top portion of the steel material and the conveyance speed of the steel material.
(S3) The temperature of the tail end portion is estimated from the temperature of the head portion. The temperature estimation method of the tail end part assumes that the temperature at the head and tail end after cooling is the same at the same time, the same position, that is, the head and tail end until entering the induction heating device. Estimate how much the temperature drop due to cooling from the time difference. In addition, in order to increase the accuracy, it is also possible to store the temperature difference between the head portion and the tail end portion of the steel material under the same conditions in the past and estimate the temperature of the tail end portion based on the value. .
(S4) The heating target temperature in each induction heating device for obtaining the final target temperature for the head portion and the tail portion is determined by a method such as heat transfer calculation.
(S5) Of the plurality of induction heating devices installed in the line, the heating target temperature of the leading portion of the jth induction heating device from the head is Tt (j), and the heating target temperature of the tail end portion is Tb (j). , Tt (j) and Tb (j) are calculated as electric power amounts Pt (j) and Pb (j).
(S6) The calculated set power Pt (j) is output to the power supply device in synchronization with the movement of the leading portion of the steel material.
(S7) The temperature of the i-th imaginary part of the steel material is read as the steel material is conveyed and the longitudinal position of the steel material changes.
(S8) The control device corrects the heating target temperature Tt (j) from the measured temperature, and calculates a new heating target temperature Ti (j) of the i-th virtual part from the head.
(S9) New electric power Pi (j) supplied to the induction heating device j is calculated from the new heating target temperature Ti (j).
ここで、Ｐｉ（ｊ）は以下の式で表される。 Here, Pi (j) is expressed by the following equation.
Ｐｉ(ｊ)＝（Ｐｔ(ｊ)−Ｐｂ(ｊ)）／（Ｔｔ−Ｔｂ）＊（Ｔｉ−Ｔｔ）＋Ｐｔ（ｊ）
Ｐｔ：先頭部分電力、Ｐｂ：尾端部分電力、Ｐｉ：仮想部分ｉでの電力
Ｔｔ：先端部分温度、Ｔｂ：尾端部分温度、Ｔｉ：仮想部分ｉの温度
（Ｓ１０）鋼材のｉ番目の仮想部分の搬送に同期して、算定した電力Ｐｉ（ｊ）を電力供給装置に出力する。
Pi (j) = (Pt (j) −Pb (j)) / (Tt−Tb) * (Ti−Tt) + Pt (j)
Pt: head partial power, Pb: tail end partial power, Pi: power at virtual part i Tt: tip part temperature, Tb: tail end part temperature, Ti: temperature of virtual part i (S10) i-th virtual of steel The calculated power Pi (j) is output to the power supply device in synchronization with the conveyance of the portion.
上述した２つの方法は、どちらを使用してもよく、装置構成のレイアウトや演算装置の能力、鋼材の種類（製造方法による長手方向の温度分布の程度）に合わせて適宜選択可能である。特に、鋼材の長手方向の温度変化が大きい場合には、第1実施形態[供給電力制御方法１]を用いると尾端部位置になるにつれて算出誤差が大きくなるため、第２実施形態[供給電力制御方法２]の方がより精度の高い制御が可能である。 Either of the two methods described above may be used, and can be appropriately selected according to the layout of the device configuration, the capability of the arithmetic device, and the type of steel material (the degree of temperature distribution in the longitudinal direction according to the manufacturing method). In particular, when the temperature change in the longitudinal direction of the steel material is large, if the first embodiment [Supply power control method 1] is used, the calculation error increases as the tail end position is reached. The control method 2] allows more accurate control.
[供給電力制御方法３]
上記の実施の形態[供給電力制御方法１、２]にＦＦ制御を取り入れることで、さらに高精度の温度制御を行う方法を第３の実施形態として説明する。
[Supply power control method 3]
A method for performing temperature control with higher accuracy by incorporating FF control into the above embodiment [Supply
実施の形態１、２のように、数式モデルを使って電力設定を行う際には、数式モデルの誤差により温度に誤差が生じる場合がある。このため、誘導加熱装置の出側に設置された温度検出器で加熱後の鋼材の温度を測定し、その実測温度に基づいて電力を補正する。 When the power setting is performed using the mathematical model as in the first and second embodiments, an error may occur in the temperature due to the mathematical model error. For this reason, the temperature of the steel material after heating is measured with a temperature detector installed on the outlet side of the induction heating device, and the electric power is corrected based on the actually measured temperature.
図３は、ＦＦ制御電力演算装置１８は、各誘導加熱装置（電力供給装置を含む）６の入り側に設置された温度検出器３の測定信号に基づいて電力を補正する。この補正出力により、誘導加熱装置（電力供給装置を含む）６は、この補正出力により電力供給量を調整し、鋼材の温度を制御する。
In FIG. 3, the FF control
たとえば、上記実施形態１、２[供給電力制御方法１、２]において、ｊ番目の誘導加熱装置での先頭部分の加熱目標温度Ｔｔ(ｊ)と、（ｊ＋１）番目の誘導加熱装置の前に設置された温度検出器で測定した先頭部分の実測温度に差が生じた場合、この温度格差を補償するために（ｊ＋１）番目の誘導加熱装置で電力の補正が必要となる。すなわち、実測温度に基づいて新たな加熱目標温度Ｔｔ(ｊ＋１)を算出し、新たな加熱目標温度Ｔｉ(ｊ＋１)から、誘導加熱装置（ｊ＋１）に供給する新たな電力Ｐｔ(ｊ＋１)を算出する。
For example, in the first and
このようなＦＦ制御を行うことにより、より高精度な温度制御が可能となり、長手方向での材質均一性に優れた高強度鋼板を製造することができる。
なお、上記実施の形態では、鋼板の長手方向で温度が徐々に低下している温度分布を持つ鋼板の実施例について説明したが、本発明はこの実施形態に限定されるものではない。
By performing such FF control, temperature control with higher accuracy becomes possible, and a high-strength steel sheet excellent in material uniformity in the longitudinal direction can be manufactured.
In addition, although the said embodiment demonstrated the Example of the steel plate with the temperature distribution which temperature fell gradually in the longitudinal direction of a steel plate, this invention is not limited to this embodiment.
たとえば、加速冷却の条件によっては、鋼板の先頭部と尾端部が中間部分に較べて温度が低下する場合がある。このような場合、先頭部と尾端部の加熱目標温度を中間部分に較べて高く設定することで、長手方向での温度分布のバラツキを解消することができる。高温に加熱する先頭部と尾端部の長さは、鋼板の種類、製造条件によって、従来知見に基づき予めその範囲を設定しておき、その長さの部分を一定温度となるように加熱し、中間部分については実施の形態１または２[供給電力制御方法１、２]の方法で加熱すればよい。
For example, depending on the accelerated cooling conditions, the temperature may be lower at the leading end and the tail end of the steel plate than at the intermediate portion. In such a case, the variation in temperature distribution in the longitudinal direction can be eliminated by setting the heating target temperatures at the head and tail ends higher than those at the intermediate portion. The length of the head and tail ends to be heated to a high temperature is set in advance based on conventional knowledge depending on the type of steel sheet and manufacturing conditions, and the length is heated to a constant temperature. The intermediate portion may be heated by the method of
本発明の実施例について述べる。表１に示す化学成分の鋼を熱間圧延後、加速冷却を行い種々の鋼板を製造した。製造条件を表２に示す。圧延後の鋼板に、ライン上に３台直列に配置した誘導加熱装置装置を用いて焼戻しを行い、引張試験により鋼板長手方向の強度分布を測定した。 Examples of the present invention will be described. After hot-rolling steels having chemical components shown in Table 1, accelerated cooling was performed to produce various steel plates. The manufacturing conditions are shown in Table 2. The steel sheet after rolling was tempered using an induction heating apparatus arranged in series on the line, and the strength distribution in the longitudinal direction of the steel sheet was measured by a tensile test.
表３に引張試験結果を示す。本発明の温度制御方法を用いて誘導加熱装置により焼戻しを行うことにより、鋼板長手方向の強度のバラツキは大幅に低減した。
特に、FF制御を組合わせた場合、そのバラツキは最も小さくなった。
Table 3 shows the tensile test results. By performing tempering with an induction heating apparatus using the temperature control method of the present invention, the variation in strength in the longitudinal direction of the steel sheet was greatly reduced.
In particular, when FF control was combined, the variation was the smallest.
１ 誘導加熱装置
２ 鋼材
３ 温度検出器
４ 制御装置
５ 電力供給装置
６ 誘導加熱装置（電力供給装置を含む）
７ 搬送ローラ
８ 温度検出器（出側）
１８ ＦＦ制御電力演算装置
DESCRIPTION OF
7 Transport roller 8 Temperature detector (exit side)
18 FF control power calculation device
Claims (3)
初段の誘導加熱装置の入り側に設けられた温度検出器で前記鋼材の先頭部分の温度を実測し、それぞれの誘導加熱装置毎の目標加熱温度を算出して前記鋼材の先頭部分に供給する電力を決定する工程と、
前記鋼材の先頭より後の部分においては、前記温度検出器で検出された温度と先頭部分の温度差に応じてそれぞれの誘導加熱装置毎の目標加熱温度を補正して新たな目標加熱温度を算出し、先頭より後の部分に供給する新たな電力を決定する工程と、
前記鋼材の移動に合わせて、それぞれの誘導加熱装置に前記決定された電力を制御して供給する工程とを有することを特徴とする鋼板長手方向の材質均一性に優れた高強度鋼板の製造方法。
After hot rolling, after accelerated cooling or direct quenching, in a method for producing a high-strength steel sheet that performs tempering using an induction heating device installed on a rolling line,
Measure the temperature of the top part of the steel material with a temperature detector provided on the entrance side of the induction heating device in the first stage, calculate the target heating temperature for each induction heating device, and supply the power to the top part of the steel material A step of determining
In the part after the head of the steel material, a new target heating temperature is calculated by correcting the target heating temperature for each induction heating device according to the temperature difference between the temperature detected by the temperature detector and the head part. And determining a new power to be supplied to the portion after the head,
A method for producing a high-strength steel sheet excellent in material uniformity in the longitudinal direction of the steel sheet, comprising the step of controlling and supplying the determined power to each induction heating device in accordance with the movement of the steel material .
初段の誘導加熱装置の入り側に設けられた温度検出器で前記鋼材の先頭部分の温度を実測し、それぞれの誘導加熱装置毎の目標加熱温度を算出して前記鋼材の先頭部分に供給する電力を決定する工程と、
前記鋼材の先頭部分の実測温度から、前記鋼材の尾端部分の温度を推定し、それぞれの誘導加熱装置毎の目標加熱温度を補正して新たな目標加熱温度を算出し、前記鋼材の尾端部分に供給する電力を決定する工程と、
前記鋼材の先頭部分と尾端部分に挟まれた中間部分においては、前記先端部分の実測温度と尾端部分の推定温度と、前記中間部分の各々の実測温度とに基づいて、それぞれの誘導加熱装置毎の目標加熱温度を補正して新たな目標加熱温度を算出し、中間部分に供給する新たな電力を決定する工程と、
前記鋼材の移動に合わせて、それぞれの誘導加熱装置に前記決定された電力を制御して供給する工程とを有することを特徴とする鋼板長手方向の材質均一性に優れた高強度鋼板の製造方法。
After hot rolling, after accelerated cooling or direct quenching, in a method for producing a high-strength steel sheet that performs tempering using an induction heating device installed on a rolling line,
Measure the temperature of the top part of the steel material with a temperature detector provided on the entrance side of the induction heating device in the first stage, calculate the target heating temperature for each induction heating device, and supply the power to the top part of the steel material A step of determining
From the measured temperature of the top portion of the steel material, the temperature of the tail end portion of the steel material is estimated, a new target heating temperature is calculated by correcting the target heating temperature for each induction heating device, and the tail end of the steel material Determining the power supplied to the part;
In the intermediate portion sandwiched between the head portion and the tail end portion of the steel material, induction heating is performed based on the measured temperature of the tip portion, the estimated temperature of the tail end portion, and the measured temperature of each of the intermediate portions. Correcting the target heating temperature for each device, calculating a new target heating temperature, and determining new power to be supplied to the intermediate part; and
A method for producing a high-strength steel sheet excellent in material uniformity in the longitudinal direction of the steel sheet, comprising the step of controlling and supplying the determined power to each induction heating device in accordance with the movement of the steel material .
補正された目標加熱温度に基づき次の誘導加熱装置に供給する新たな電力を決定する工程とを有することを特徴とする請求項１または２に記載の鋼板長手方向の材質均一性に優れた高強度鋼板の製造方法。 Measuring the temperature in the longitudinal direction of the steel sheet after induction heating by a temperature detector installed between the induction heating devices, and correcting the target heating temperature of the next induction heating device from the measured temperature;
3. A step of determining a new electric power to be supplied to the next induction heating device based on the corrected target heating temperature, and having a high material uniformity in the longitudinal direction of the steel sheet according to claim 1 or 2. A method for producing a strength steel plate.
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| RU2617085C2 (en) * | 2012-09-03 | 2017-04-19 | ДжФЕ СТИЛ КОРПОРЕЙШН | Device for quick heating of continuous oxyging line |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2008126911A1 (en) * | 2007-04-05 | 2008-10-23 | Nippon Steel Corporation | Method of continuous annealing for steel strip with curie point and continuous annealing apparatus therefor |
| RU2617085C2 (en) * | 2012-09-03 | 2017-04-19 | ДжФЕ СТИЛ КОРПОРЕЙШН | Device for quick heating of continuous oxyging line |
| US10072318B2 (en) | 2012-09-03 | 2018-09-11 | Jfe Steel Corporation | Rapid heating apparatus of continuous annealing line |
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