JP3945212B2 - Heat treatment apparatus and method for thick steel plate - Google Patents
Heat treatment apparatus and method for thick steel plate Download PDFInfo
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- JP3945212B2 JP3945212B2 JP2001314160A JP2001314160A JP3945212B2 JP 3945212 B2 JP3945212 B2 JP 3945212B2 JP 2001314160 A JP2001314160 A JP 2001314160A JP 2001314160 A JP2001314160 A JP 2001314160A JP 3945212 B2 JP3945212 B2 JP 3945212B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description
【０００１】
【発明の属する技術分野】
本発明は、厚鋼板の焼入れ・焼鈍し・焼戻し等の熱処理プロセスにおいて、高能率で急速加熱に好適なソレノイド型誘導加熱装置を用いた厚鋼板の熱処理装置および熱処理方法に関するものである。
【０００２】
【従来の技術】
厚鋼板の焼入れ・焼鈍し・焼戻し等の熱処理プロセスを圧延ラインと直結して行う等の場合、厚鋼板を所定の温度に急速に加熱することが必要となる。
【０００３】
従来、熱間薄板圧延では、ソレノイド型誘導加熱装置を用いて圧延ライン上で薄鋼板を急速加熱する方法が知られており、その温度制御のために、特開平１０−２７６７８号公報に記載のように、ソレノイド型誘導加熱装置の入出口温度を計測しフィードフォワード制御及びフィードバック制御を実施するという技術や、特開平１０−２０２３１１号公報に記載のように、ソレノイド型誘導加熱装置の入出口温度と仕上圧延機の出口温度を計測しフィードフォワード制御及びフィードバック制御を実施するという技術が存在する。
【０００４】
【発明が解決しようとする課題】
ソレノイド型誘導加熱装置は急速加熱に好適であるが、鋼板の表層部近傍が加熱されるので、厚鋼板の焼入れ・焼鈍し・焼戻し等の熱処理プロセスに適用する場合、下記の問題を解決することが必要である。
▲１▼厚鋼板内の温度分布が均一になるように加熱すること。すなわち、板厚中心と表面の温度差を最小化すること。温度分布が不均一な場合、最終製品の品質に悪影響を及ぼす。
▲２▼加熱過程で所定の上限温度を超えないこと。加熱中に相変態点を超えると鋼中添加元素の析出が起こり品質に悪影響を与える。さらに、磁気変態点を超えると電磁誘導の浸透深さが変化してしまい制御が難しくなる。
【０００５】
つまり、厚鋼板の板厚方向の温度均一化と表面温度の上限管理を行いながら、平均温度が目標温度になるように制御することが必要となる。
【０００６】
これに対し、前述の特開平１０−２７６７８号公報や特開平１０−２０２３１１号公報に記載の技術は、対象が薄鋼板であるとともに熱間仕上圧延前の加熱であるので、板厚方向の温度均一性確保や表面温度の上限管理が技術的課題ではなく、最終製品の品質に直接影響を及ぼす厚鋼板の熱処理に対しては直ちに適用することはできない。
【０００７】
したがって、本発明の目的は、厚鋼板の板厚方向の温度均一化と表面温度の上限管理を行いながら、平均温度が目標熱処理温度になるように精度良く加熱することができる厚鋼板の熱処理装置および熱処理方法を提供することにある。
【０００８】
【課題を解決するための手段】
請求項１に係る発明は、０．３ｍ以上の間隔をとって直列に配置された複数個のソレノイド型誘導加熱装置と、第１番目のソレノイド型誘導加熱装置の入口と各ソレノイド型誘導加熱装置の間で厚鋼板表面温度が板厚方向平均温度となる地点と最終ソレノイド型誘導加熱装置の出口で厚鋼板表面温度が板厚方向平均温度となる地点にそれぞれ設けられた温度計測手段とを有することを特徴とする厚鋼板の熱処理装置である。
【０００９】
請求項２に記載の発明は、第１番目のソレノイド型誘導加熱装置の入口に設けられた温度計測手段が厚鋼板の板厚方向平均温度を計測する温度計測手段であることを特徴とする請求項１に記載の厚鋼板の熱処理装置である。
【００１０】
請求項３に係る発明は、０．３ｍ以上の間隔をとって直列に配置された複数個のソレノイド型誘導加熱装置を通過させて厚鋼板を加熱するとともに、予め各ソレノイド型誘導加熱装置を通過する前の厚鋼板の目標温度をそれぞれ設定しておき、第１番目のソレノイド型誘導加熱装置の入口と各ソレノイド型誘導加熱装置の間で厚鋼板表面温度が板厚方向平均温度となる地点において、各ソレノイド型誘導加熱装置を通過する前の厚鋼板の温度を実測し、当該実測温度の前記目標温度からの偏差を求め、当該温度偏差を前方補償することを特徴とする厚鋼板の熱処理方法である。
【００１１】
請求項４に係る発明は、０．３ｍ以上の間隔をとって直列に配置された複数個のソレノイド型誘導加熱装置を通過させて厚鋼板を加熱するとともに、予め各ソレノイド型誘導加熱装置を通過した後の厚鋼板の目標温度をそれぞれ設定しておき、各ソレノイド型誘導加熱装置の間で厚鋼板表面温度が板厚方向平均温度となる地点と最終ソレノイド型誘導加熱装置の出口で厚鋼板表面温度が板厚方向平均温度となる地点において、各ソレノイド型誘導加熱装置を通過した後の厚鋼板の温度を実測し、当該実測温度の前記目標温度からの偏差を求め、当該温度偏差を後方補償することを特徴とする厚鋼板の熱処理方法である。
【００１２】
請求項５に係る発明は、０．３ｍ以上の間隔をとって直列に配置された複数個のソレノイド型誘導加熱装置を通過させて厚鋼板を加熱するとともに、第１番目のソレノイド型誘導加熱装置の入口と各ソレノイド型誘導加熱装置の間で厚鋼板表面温度が板厚方向平均温度となる地点と最終ソレノイド型誘導加熱装置の出口で厚鋼板表面温度が板厚方向平均温度となる地点において、各ソレノイド型誘導加熱装置を通過前と通過後の厚鋼板の温度を実測し、当該実測温度から各ソレノイド型誘導加熱装置の実績加熱効率を算定し、算定された実績加熱効率に基づいて各ソレノイド型誘導加熱装置の加熱効率を補正することを特徴とする厚鋼板の熱処理方法である。
【００１３】
【発明の実施の形態】
図１は、本発明の厚鋼板の熱処理設備の一実施形態を示す説明図である。第1番目のソレノイド型誘導加熱装置Ｈ1、第２番目のソレノイド型誘導加熱装置Ｈ2 、………、第ｎ番目のソレノイド型誘導加熱装置Ｈnとｎ個のソレノイド型誘導加熱装置が直列に所定の間隔Ｌをとって配置されており、搬送ローラ２に載った厚鋼板１が各ソレノイド型誘導加熱装置を順次通過して加熱されるようになっている。そして、第1番目のソレノイド型誘導加熱装置Ｈ1の入口には第1番目の温度計Ｒ1、第２番目のソレノイド型誘導加熱装置Ｈ2の入口には第２番目の温度計Ｒ2、………、第ｎ番目のソレノイド型誘導加熱装置Ｈnの入口には第ｎ番目の温度計Ｒn がそれぞれ設置されているとともに、第ｎ番目のソレノイド型誘導加熱装置Ｈnの出口には第ｎ＋１番目の温度計Ｒn+1が設置されている。
【００１４】
間隔をとって配置された各ソレノイド型誘導加熱装置を厚鋼板が通過していくと、図２に示すように、各ソレノイド型誘導加熱装置で厚鋼板の表層部近傍が加熱されるが、ソレノイド型誘導加熱装置とソレノイド型誘導加熱装置との間では、表層部近傍の熱が熱伝導により板厚内部温度を上昇させるとともに表面温度を下げ、板厚方向の均熱化が図られる。したがって、ソレノイド型誘導加熱装置間の間隔を、熱処理能率、加熱能力、通過速度等を考慮して、板厚方向均熱化に必要な時間が得られるように定めておけば、厚鋼板の板厚方向の温度均一化と表面温度の上限制約を満足しながら、目標熱処理温度になるように加熱することが可能である。
【００１５】
そして、実操業では熱処理前の厚鋼板間での温度変動や厚鋼板内での長手方向の温度変動等が存在するので、精度良い管理を行うためには、厚鋼板の温度を実測して、その結果に基づいてソレノイド型誘導加熱装置を制御していくことが必要となる。その際の厚鋼板の温度測定は、板厚方向での均熱化によって表面温度がほぼ平均温度となる地点で行えばよい。
【００１６】
なお、熱処理開始前の厚鋼板は板厚方向に温度分布をもっている可能性があるので、第1番目のソレノイド型誘導加熱装置の入口に配置された温度計は、例えば、特開２０００−１２１４５５号公報に記載のような超音波を用いて鋼材内部の温度分布を測定する装置のように、厚鋼板の板厚方向の平均温度を計測できる温度計であることが望ましい。
【００１７】
以下に、本発明の厚鋼板の熱処理方法の第１の実施形態を説明する。
【００１８】
まず、厚鋼板の寸法、初期温度、目標熱処理温度、表面温度の上限制約等に基づいて、厚鋼板の昇温スケジュール、すなわち、ソレノイド型誘導加熱装置Ｈi（ｉ＝１〜ｎ）での入口目標温度Ｔｍi（ｉ＝１〜ｎ）と出口目標温度Ｔｎi（ｉ＝１〜ｎ）及び通過速度Ｖを初期設定する。その際、第ｉ番目のソレノイド型誘導加熱装置Ｈiの出口目標温度Ｔｎiが第ｉ＋１番目のソレノイド型誘導加熱装置Ｈi+1の入口目標温度Ｔｍi+1に対応するが、第ｉ番目のソレノイド型誘導加熱装置Ｈiと第ｉ＋１番目のソレノイド型誘導加熱装置Ｈi+1との間での空冷による温度降下ΔＴａiが無視できない場合には、それを見込んで出口目標温度Ｔｎiと入口目標温度Ｔｍi+1を設定する。そして、ソレノイド型誘導加熱装置Ｈiの入口目標温度Ｔｍiと出口目標温度とＴｎiの差がソレノイド型誘導加熱装置Ｈiでの目標昇温量となるので、ソレノイド型誘導加熱装置Ｈiでの必要な加熱電力Ｐｈiおよび投入電力Ｐｅiが下記の式により定まる。
【００１９】
加熱電力Ｐｈi＝Ｃ・（Ｔｎi−Ｔｍi）ｈ・ｗ・Ｖ
投入電力Ｐｅi＝Ｐｈi／νi
ここで、Ｃ：厚鋼板の比熱
ｈ：厚鋼板の板厚
ｗ：厚鋼板の板幅
νi：第ｉ番目のソレノイド型誘導加熱装置の加熱効率
次に、上記のような初期設定に基づいて厚鋼板の熱処理を開始した後、図３に示すように、第ｉ番目のソレノイド型誘導加熱装置Ｈiの入口に設定された温度計Ｒiで測定した入口実測温度Ｔｒiを入口目標温度Ｔｍiと比較し、偏差がある場合には、その温度偏差を加熱電力ΔＰｈiに変換し、それを加熱効率νiで除して投入電力ΔＰｅiを算出し、ソレノイド型誘導加熱装置Ｈiへの投入電力ＰｅiをΔＰｅiだけ修正する。
【００２０】
これによって、目標熱処理温度および表面温度の上限制約を考慮して定めた昇温スケジュールにしたがって厚鋼板が加熱されるようになる。
【００２１】
このように、厚鋼板の温度を実測し、厚鋼板の実測温度の目標温度からの偏差を求め、その温度偏差を前方補償するという制御を行うことにより、厚鋼板間での熱処理開始前温度の変動や厚鋼板内での長手方向の温度変動があっても、板厚方向の温度均一化と表面温度の上限管理を行いながら、平均温度が目標熱処理温度になるように精度良く加熱することができる。
【００２２】
以下に、本発明の厚鋼板の熱処理方法の第２の実施形態を説明する。
【００２３】
まず、厚鋼板の昇温スケジュール、すなわち、ソレノイド型誘導加熱装置Ｈi（ｉ＝１〜ｎ）の入口目標温度Ｔｍi（ｉ＝１〜ｎ）と出口目標温度Ｔｎi（ｉ＝１〜ｎ）および通過速度Ｖの初期設定については、前述の第１の実施形態と同様である。
【００２４】
次に、上記のような初期設定に基づいて厚鋼板の熱処理を開始した後、図４に示すように、第ｉ＋１番目のソレノイド型誘導加熱装置Ｈi+1の入口に設定された温度計Ｒi+1で測定した入口実測温度Ｔｒi+1を入口目標温度Ｔｍi+1と比較し、偏差がある場合には、その温度偏差をＰＩＤ調節器を介して加熱電力ΔＰｈiに変換し、それを加熱効率νiで除して投入電力ΔＰｅiを算出し、ソレノイド型誘導加熱装置Ｈiへの投入電力ＰｅiをΔＰｅiだけ修正する。
【００２５】
これによって、目標熱処理温度および表面温度の上限制約を考慮して定めた昇温スケジュールにしたがって厚鋼板が加熱されるようになる。
【００２６】
このように、厚鋼板の温度を実測し、厚鋼板の実測温度の目標温度からの偏差を求め、その温度偏差を後方補償するという制御を行うことにより、厚鋼板間での熱処理開始前温度の変動や厚鋼板内での長手方向の温度変動があっても、板厚方向の温度均一化と表面温度の上限管理を行いながら、平均温度が目標熱処理温度になるように精度良く加熱することができる。
【００２７】
なお、上記の第１の実施形態および第２の実施形態においては、以下の点を考慮して実施することが望ましい。
▲１▼加熱中は、厚鋼板は全長にわたり一定速度で通過させる。温度測定の結果、あるソレノイド型誘導加熱装置で速度変更の必要があったとしても、速度を変化させると他のソレノイド型誘導加熱装置で温度変動を発生させることになる。
▲２▼厚鋼板の初期温度の変動は、できるだけ第１番目のソレノイド型誘導加熱装置で除去する。第２番目のソレノイド型誘導加熱装置以後での加熱電力増加は表面温度上限を超える危険性がある。
▲３▼第１の実施形態および第２の実施形態を併用することも効果的である。すなわち、第ｉ番目のソレノイド型誘導加熱装置の投入電力に過不足が生じた場合、それによる温度偏差は第ｉ＋１番目のソレノイド型誘導加熱装置で補償すると同時に、第ｉ番目のソレノイド型誘導加熱装置の誤差を速やかに修正する。厚鋼板の温度変動はフィードフォワード制御で補償し、ソレノイド型誘導加熱装置の加熱誤差はフィードバック制御で修正する。
【００２８】
以下に、本発明の厚鋼板の熱処理方法の第３の実施形態を説明する。
【００２９】
複数台直列配置されたソレノイド型誘導加熱装置で誘導加熱する場合、各ソレノイド型誘導加熱装置での加熱温度域は下流に行くほど高くなるため、それぞれのソレノイド型誘導加熱装置の加熱効率は一様ではない。これは厚鋼板の温度により透磁率が変わるためである。したがって、ソレノイド型誘導加熱装置の加熱効率を精度良く推定することが重要である。
【００３０】
図５に示すように、第ｉ番目のソレノイド型誘導加熱装置Ｈiの入口に設定された温度計Ｒiで測定した実測温度Ｔｒiと第ｉ＋１番目のソレノイド型誘導加熱装置Ｈi+1の入口に設定された温度計Ｒi+1で測定した実測温度Ｔｒi+1とから昇温量を求め、それにソレノイド型誘導加熱装置Ｈiを通過後の空冷温度降下分ΔＴａiを加えてソレノイド型誘導加熱装置Ｈiの正味昇温量実績を算定し、それを加熱電力に変換して加熱電力実績Ｐｈi Oを算出する。そして、加熱電力実績Ｐｈi Oを投入電力実績Ｐｅi Oで除すことによりソレノイド型誘導加熱装置Ｈiの実績加熱効率νi Oを算出する。すなわち、
加熱電力実績Ｐｈi O＝Ｃ・（Ｔｒi+1−Ｔｒi＋ΔＴａi）ｈ・ｗ・Ｖ
実績加熱効率νi O＝加熱電力実績Ｐｈi O／投入電力実績Ｐｅi O
ここで、Ｃ：厚鋼板の比熱
ｈ：厚鋼板の板厚
ｗ：厚鋼板の板幅
Ｖ：通過速度
そして、実績加熱効率νi Oを、次の厚鋼板の加熱に際して用いるソレノイド型誘導加熱装置Ｈiの加熱効率νiに反映する。実績加熱効率νi Oの反映方法は、例えば下記のように指数平滑等の方法を用いても良い。
【００３１】
νi＝（１−χ）・νi-1 O＋χ・νi O （０＜χ≦１）
以上のように、厚鋼板の温度を実測し、ソレノイド型誘導加熱装置の加熱効率の推定精度を高めることにより、板厚方向の温度均一化と表面温度の上限管理を行いながら、平均温度が目標熱処理温度になるように精度良く加熱することができる。
【００３２】
なお、これまでに述べた実施形態においては、厚鋼板の平均温度を測定できるように、板厚方向での均熱化によって表面温度が平均温度となる各ソレノイド型誘導加熱装置の入口に温度計を設置して温度測定を行なっているが、それに加えて、各ソレノイド型誘導加熱装置の出口に温度計を設置して各ソレノイド型誘導加熱装置を通過直後の厚鋼板の表面温度を測定することで、上限温度管理を直接行うことができる。
【００３３】
また、前述の特開２０００−１２１４５５号公報記載の鋼材内部温度測定装置を各ソレノイド型誘導加熱装置の出口に設置して、各ソレノイド型誘導加熱装置を通過直後の厚鋼板の表面温度および内部温度を測定することによって、一層精度の良い温度管理を行うことも可能である。
【００３４】
【実施例】
図６は、本発明の厚鋼板の熱処理装置の圧延ライン上に配置した例である。加熱炉３、圧延機４、冷却装置５、ホットレベラ６、誘導加熱装置７、クーリングベッド８の順に配置されている。誘導加熱装置７は、板厚８〜５０ｍｍ、最大板幅４６００ｍｍの厚鋼板を１４０Ｔ／Ｈの加熱能率で、板厚方向の温度均一化と表面温度の上限制約を満足しながら加熱できるように、０．３ｍ以上の間隔で直列に配置された４台のソレノイド型誘導加熱装置からなっており、各ソレノイド型誘導加熱装置の入口と第４番目のソレノイド型誘導加熱装置の出口には温度計が設置されている。
【００３５】
そして、前述の本発明の熱処理方法の第１の実施形態によって、板厚２５ｍｍ、板幅４５００ｍｍで加熱前温度が長手方向で変動している普通鋼の厚鋼板を、初期温度２００℃から目標熱処理温度６５０℃まで、加熱上限温度を７００℃として加熱した場合を、本発明の実施例として示す。なお、本発明の熱処理方法を適用しなかった場合を比較例として示す。
【００３６】
図７は、それによる厚鋼板の中心温度及び表面温度の推移で、（ａ）は本発明の実施例のものであり、（ｂ）は比較例のものである。
【００３７】
本発明の実施例では、図７（ａ）に示すように、厚鋼板の先端が第１番目のソレノイド型誘導加熱装置で加熱を開始してから１秒後に測定した入口実測温度が入口目標温度２００℃に比べて３０℃高くなったが、フィードフォワード制御によってこの温度変動を第1番目のソレノイド型誘導加熱装置への投入電力で補償することにより、第1番目のソレノイド型誘導加熱装置の出口以降では、厚鋼板長手方向の温度変動がほとんど無くなっている。
【００３８】
これに対して、比較例では、図７（ｂ）に示すように、第1番目のソレノイド型誘導加熱装置の出口以降も加熱前の厚鋼板長手方向の温度変動がそのまま持続している。
【００３９】
【発明の効果】
以上述べたように本発明によれば、所定の間隔をとって直列に配置された複数個のソレノイド型誘導加熱装置を通過させて厚鋼板を加熱するともに、予め各ソレノイド型誘導加熱装置を通過する前の厚鋼板の目標温度をそれぞれ設定しておき、各ソレノイド型誘導加熱装置を通過する前に測定した厚鋼板の実測温度と前記目標温度との偏差を求め、温度偏差を前方補償あるいは後方補償することにより、厚鋼板の板厚方向の温度均一化と表面温度の上限管理を行いながら、平均温度が目標熱処理温度になるように精度良く加熱することができる。
【図面の簡単な説明】
【図１】本発明の厚鋼板の熱処理設備の一実施形態を示す図である。
【図２】本発明の厚鋼板の熱処理設備を用いた場合の厚鋼板の温度推移を示す図である。
【図３】本発明の厚鋼板の熱処理方法の第１の実施形態を示す図である。
【図４】本発明の厚鋼板の熱処理方法の第２の実施形態を示す図である。
【図５】本発明の厚鋼板の熱処理方法の第３の実施形態を示す図である。
【図６】本発明の厚鋼板の熱処理装置の配置例を示す図である。
【図７】本発明の厚鋼板の熱処理方法の実施例を説明する図である。
（ａ）実施例の温度推移を示す図である。
（ｂ）比較例の温度推移を示す図である。
【符号の説明】
１ 厚鋼板
２ 搬送ロール
３ 加熱炉
４ 圧延機
５ 冷却装置
６ ホットレベラ
７ 誘導加熱装置
８ クーリングベッド
Ｈi（ｉ＝１〜ｎ） ソレノイド型誘導加熱装置
Ｒi（ｉ＝１〜ｎ＋１） 温度計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat treatment apparatus and a heat treatment method for a thick steel plate using a solenoid type induction heating device suitable for rapid heating in a heat treatment process such as quenching, annealing, and tempering of the thick steel plate.
[0002]
[Prior art]
When a heat treatment process such as quenching / annealing / tempering of a thick steel plate is performed directly with a rolling line, it is necessary to rapidly heat the thick steel plate to a predetermined temperature.
[0003]
Conventionally, in hot sheet rolling, a method of rapidly heating a sheet steel on a rolling line using a solenoid type induction heating device is known. For temperature control, it is described in JP-A-10-27678. As described above, the technology for measuring the inlet / outlet temperature of the solenoid type induction heating device and performing the feedforward control and the feedback control, and the inlet / outlet temperature of the solenoid type induction heating device as described in JP-A-10-20211 In addition, there is a technique of measuring the outlet temperature of the finishing mill and performing feedforward control and feedback control.
[0004]
[Problems to be solved by the invention]
Solenoid induction heating equipment is suitable for rapid heating, but the surface layer near the steel sheet is heated, so when applied to heat treatment processes such as quenching, annealing, and tempering thick steel sheets, the following problems should be solved. is required.
(1) Heating so that the temperature distribution in the thick steel plate is uniform. That is, minimize the temperature difference between the thickness center and the surface. If the temperature distribution is not uniform, the quality of the final product will be adversely affected.
(2) The predetermined upper limit temperature must not be exceeded during the heating process. Exceeding the phase transformation point during heating causes precipitation of added elements in the steel and adversely affects the quality. Furthermore, if the magnetic transformation point is exceeded, the penetration depth of electromagnetic induction changes and control becomes difficult.
[0005]
That is, it is necessary to control the average temperature to be the target temperature while performing uniform temperature in the thickness direction of the thick steel plate and managing the upper limit of the surface temperature.
[0006]
On the other hand, since the technique described in the above-mentioned JP-A-10-27678 and JP-A-10-202111 is a thin steel plate and heating before hot finish rolling, the temperature in the plate thickness direction Ensuring uniformity and controlling the upper limit of the surface temperature are not technical issues, and cannot be applied immediately to heat treatment of thick steel sheets that directly affect the quality of the final product.
[0007]
Accordingly, an object of the present invention is to provide a steel plate heat treatment apparatus capable of accurately heating so that the average temperature becomes the target heat treatment temperature while making the temperature uniform in the plate thickness direction of the steel plate and managing the upper limit of the surface temperature. And providing a heat treatment method.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 includes a plurality of solenoid type induction heating devices arranged in series at intervals of 0.3 m or more, an inlet of the first solenoid type induction heating device, and each solenoid type induction heating device. steel plate surface temperature and a temperature measuring means provided respectively at the point where the steel plate surface temperature at the exit point and the final solenoid induction heating apparatus in accordance with the thickness direction average temperature becomes thickness direction average temperature between the It is the heat processing apparatus of the thick steel plate characterized by the above-mentioned.
[0009]
The invention according to
[0010]
In the invention according to claim 3, the thick steel plate is heated by passing through a plurality of solenoid type induction heating devices arranged in series at intervals of 0.3 m or more, and each solenoid type induction heating device is passed in advance. The target temperature of the thick steel plate before setting is set, and at the point where the surface temperature of the thick steel plate becomes the average thickness direction temperature between the inlet of the first solenoid type induction heating device and each solenoid type induction heating device. The method for heat treating a thick steel plate, characterized by actually measuring the temperature of the thick steel plate before passing through each solenoid induction heating device, obtaining a deviation of the measured temperature from the target temperature, and forwardly compensating the temperature deviation It is.
[0011]
In the invention according to
[0012]
Invention is to heat the steel plate is passed through a plurality of solenoid-type induction heating device arranged in series spaced above 0.3 m, the first solenoid type induction heating device according to claim 5 At the point where the steel plate surface temperature becomes the plate thickness direction average temperature between the inlet and each solenoid type induction heating device and at the point where the plate thickness surface temperature becomes the plate thickness direction average temperature at the exit of the final solenoid type induction heating device, Measure the temperature of the steel plate before and after passing through each solenoid type induction heating device, calculate the actual heating efficiency of each solenoid type induction heating device from the measured temperature, and calculate each solenoid based on the calculated actual heating efficiency A heat treatment method for a thick steel plate, wherein the heating efficiency of the mold induction heating device is corrected.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an explanatory view showing an embodiment of a heat treatment facility for thick steel plates according to the present invention. First solenoid type induction heating device H 1 , second solenoid type induction heating device H 2 ,..., Nth solenoid type induction heating device H n and n solenoid type induction heating devices are connected in series. The thick steel plate 1 placed on the
[0014]
As the thick steel plates pass through the solenoid induction heating devices arranged at intervals, as shown in FIG. 2, the vicinity of the surface layer portion of the thick steel plates is heated by the solenoid induction heating devices. Between the mold induction heating device and the solenoid type induction heating device, heat in the vicinity of the surface layer portion increases the plate thickness internal temperature by heat conduction, lowers the surface temperature, and achieves uniform temperature in the plate thickness direction. Therefore, if the interval between solenoid induction heating devices is determined so that the time required for soaking in the plate thickness direction can be obtained in consideration of heat treatment efficiency, heating capability, passage speed, etc. Heating can be performed to a target heat treatment temperature while satisfying the temperature uniformity in the thickness direction and the upper limit of the surface temperature.
[0015]
And in actual operation, there are temperature fluctuations between the steel plates before heat treatment, temperature fluctuations in the longitudinal direction within the steel plates, etc., in order to perform accurate management, measure the temperature of the steel plates, It is necessary to control the solenoid induction heating device based on the result. The temperature measurement of the thick steel plate at that time may be performed at a point where the surface temperature becomes substantially the average temperature by soaking in the thickness direction.
[0016]
Since the thick steel plate before the start of heat treatment may have a temperature distribution in the plate thickness direction, a thermometer disposed at the inlet of the first solenoid type induction heating device is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-121455. It is desirable to be a thermometer that can measure the average temperature in the thickness direction of a thick steel plate, such as a device that measures the temperature distribution inside a steel material using ultrasonic waves as described in the publication.
[0017]
Below, 1st Embodiment of the heat processing method of the thick steel plate of this invention is described.
[0018]
First, based on the dimensions of the thick steel plate, the initial temperature, the target heat treatment temperature, the upper limit restriction on the surface temperature, etc., the temperature rise schedule of the thick steel plate, that is, the inlet in the solenoid type induction heating device H i (i = 1 to n) The target temperature Tm i (i = 1 to n), the outlet target temperature Tn i (i = 1 to n), and the passing speed V are initialized. At that time, although the outlet target temperature Tn i of the i-th solenoid induction heating device H i corresponds to the inlet target temperature Tm i + 1 of the (i + 1) th solenoid induction heating device H i + 1, the i-th If the temperature drop ΔTa i due to air cooling between the solenoid type induction heating device H i and the (i + 1) th solenoid type induction heating device H i + 1 is not negligible, the outlet target temperature Tn i An inlet target temperature Tm i + 1 is set. Then, the difference between the inlet target temperature Tm i and the outlet target temperature and Tn i solenoid-type induction heating device H i is the target temperature Yutakaryou of a solenoid-type induction heating device H i, a solenoid-type induction heating device H i Necessary heating power Ph i and input power Pe i are determined by the following equations.
[0019]
Heating power Ph i = C · (Tn i −Tm i ) h · w · V
Input power Pe i = Ph i / ν i
Here, C: specific heat of thick steel plate h: plate thickness w of thick steel plate w: plate width ν i of thick steel plate: heating efficiency of i-th solenoid type induction heating device Next, based on the initial setting as described above after starting the heat treatment the steel plate, as shown in FIG. 3, the i-th solenoid induction heating device H inlet actual temperature measured at the set thermometer R i to the inlet of the i Tr i inlet target temperature Tm compared to i, if there is a deviation, and converts the temperature deviation the heating power .DELTA.PH i, which was divided by the heating efficiency [nu i calculate the input power .DELTA.Pe i, to the solenoid-type induction heating device H i The input power Pe i is corrected by ΔPe i .
[0020]
As a result, the thick steel plate is heated in accordance with a temperature increase schedule determined in consideration of the upper limit constraints of the target heat treatment temperature and the surface temperature.
[0021]
In this way, by actually measuring the temperature of the thick steel plate, obtaining a deviation from the target temperature of the measured temperature of the thick steel plate, and performing a control to forward compensate the temperature deviation, the temperature before the start of heat treatment between the thick steel plates Even if there are fluctuations and temperature fluctuations in the longitudinal direction within the thick steel plate, it is possible to heat accurately so that the average temperature becomes the target heat treatment temperature while performing uniform temperature in the thickness direction and controlling the upper limit of the surface temperature. it can.
[0022]
Below, 2nd Embodiment of the heat processing method of the thick steel plate of this invention is described.
[0023]
First, a temperature increase schedule for thick steel plates, that is, an inlet target temperature Tm i (i = 1 to n) and an outlet target temperature Tn i (i = 1 to n) of the solenoid induction heating device H i (i = 1 to n). ) And the initial setting of the passing speed V are the same as those in the first embodiment.
[0024]
Next, after starting the heat treatment of the thick steel plate based on the initial setting as described above, as shown in FIG. 4, the thermometer R set at the inlet of the (i + 1) th solenoid type induction heating device H i + 1. The measured inlet temperature Tri + 1 measured at i + 1 is compared with the target inlet temperature Tm i + 1, and if there is a deviation, the temperature deviation is converted into the heating power ΔPh i via the PID controller, By dividing this by the heating efficiency ν i , the input power ΔPe i is calculated, and the input power Pe i to the solenoid induction heating device H i is corrected by ΔPe i .
[0025]
As a result, the thick steel plate is heated in accordance with a temperature increase schedule determined in consideration of the upper limit constraints of the target heat treatment temperature and the surface temperature.
[0026]
In this way, by measuring the temperature of the thick steel plate, obtaining a deviation from the target temperature of the measured temperature of the thick steel plate, and performing the control of backward compensation of the temperature deviation, the temperature before the start of heat treatment between the thick steel plates Even if there are fluctuations and temperature fluctuations in the longitudinal direction within the thick steel plate, it is possible to heat accurately so that the average temperature becomes the target heat treatment temperature while performing uniform temperature in the thickness direction and controlling the upper limit of the surface temperature. it can.
[0027]
In the first embodiment and the second embodiment described above, it is desirable to implement in consideration of the following points.
(1) During heating, the thick steel plate is passed at a constant speed over the entire length. As a result of the temperature measurement, even if it is necessary to change the speed in a certain solenoid type induction heating device, if the speed is changed, the temperature fluctuation is generated in another solenoid type induction heating device.
(2) The fluctuation of the initial temperature of the thick steel plate is removed as much as possible by the first solenoid induction heating device. The increase in heating power after the second solenoid type induction heating apparatus has a risk of exceeding the upper limit of the surface temperature.
(3) It is also effective to use the first embodiment and the second embodiment together. That is, when the input power of the i-th solenoid type induction heating apparatus is excessive or insufficient, the temperature deviation caused by the power is compensated by the i + 1th solenoid type induction heating apparatus, and at the same time, the i-th solenoid type induction heating apparatus. Correct the error immediately. The temperature fluctuation of the thick steel plate is compensated by feedforward control, and the heating error of the solenoid induction heating apparatus is corrected by feedback control.
[0028]
Below, 3rd Embodiment of the heat processing method of the thick steel plate of this invention is described.
[0029]
When induction heating is performed with a plurality of solenoid induction heating devices arranged in series, the heating temperature range of each solenoid induction heating device increases as it goes downstream, so the heating efficiency of each solenoid induction heating device is uniform. is not. This is because the magnetic permeability changes depending on the temperature of the thick steel plate. Therefore, it is important to accurately estimate the heating efficiency of the solenoid type induction heating device.
[0030]
As shown in FIG. 5, the measured temperature Tr i and induction heating devices H i + 1 (i + 1) -th solenoid measured in the i-th solenoid induction heating device H thermometer was set to the inlet of i R i solenoid from the measured temperature Tr i + 1 Metropolitan measured by a thermometer R i + 1, which is set at the entrance calculated Atsushi Nobori amount, it added a cooling temperature drop .DELTA.Ta i after passing through a solenoid-type induction heating device H i The net heating amount actual result of the mold induction heating device H i is calculated, converted into heating power, and the heating power result Ph i O is calculated. Then, the actual heating efficiency ν i O of the solenoid induction heating device H i is calculated by dividing the actual heating power Ph i O by the input power actual Pe i O. That is,
Heating the actual power Ph i O = C · (Tr i + 1 -Tr i + ΔTa i) h · w · V
Actual heating efficiency ν i O = Heating power result Ph i O / Input power result Pe i O
Here, C: specific heat of thick steel plate h: plate thickness w of thick steel plate w: plate width V of thick steel plate V: passage speed and actual heating efficiency ν i O used for heating the next thick steel plate This is reflected in the heating efficiency ν i of H i . As a method of reflecting the actual heating efficiency ν i O , for example, a method such as exponential smoothing may be used as described below.
[0031]
ν i = (1-χ) · ν i-1 O + χ · ν i O (0 <χ ≦ 1)
As described above, by measuring the temperature of the thick steel plate and increasing the accuracy of estimating the heating efficiency of the solenoid induction heating device, the average temperature is targeted while maintaining the temperature uniformity in the plate thickness direction and the upper limit control of the surface temperature. Heating can be performed with high accuracy so that the heat treatment temperature is reached.
[0032]
In the embodiments described so far, a thermometer is provided at the inlet of each solenoid induction heating device where the surface temperature becomes the average temperature by soaking in the thickness direction so that the average temperature of the thick steel plate can be measured. In addition to this, a thermometer is installed at the outlet of each solenoid type induction heating device to measure the surface temperature of the steel plate immediately after passing through each solenoid type induction heating device. Thus, the upper limit temperature management can be performed directly.
[0033]
Further, the steel material internal temperature measuring device described in JP 2000-121455 A described above is installed at the outlet of each solenoid type induction heating device, and the surface temperature and internal temperature of the thick steel plate immediately after passing through each solenoid type induction heating device. By measuring the temperature, it is possible to perform temperature control with higher accuracy.
[0034]
【Example】
FIG. 6 shows an example of arrangement on the rolling line of the heat treatment apparatus for thick steel plates according to the present invention. The heating furnace 3, the rolling
[0035]
Then, according to the above-described first embodiment of the heat treatment method of the present invention, a thick steel plate of normal steel having a plate thickness of 25 mm, a plate width of 4500 mm, and a pre-heating temperature varying in the longitudinal direction is subjected to a target heat treatment from an initial temperature of 200 ° C. The case where the heating upper limit temperature is set to 700 ° C. up to a temperature of 650 ° C. is shown as an example of the present invention. In addition, the case where the heat processing method of this invention is not applied is shown as a comparative example.
[0036]
FIG. 7 shows the transition of the center temperature and the surface temperature of the thick steel plate. FIG. 7A shows the example of the present invention, and FIG. 7B shows the comparative example.
[0037]
In the embodiment of the present invention, as shown in FIG. 7 (a), the measured inlet temperature measured one second after the leading end of the thick steel plate is heated by the first solenoid type induction heating device is the target inlet temperature. Although it was 30 ° C higher than 200 ° C, by compensating for this temperature variation with the input power to the first solenoid type induction heating device by feedforward control, the outlet of the first solenoid type induction heating device Thereafter, there is almost no temperature fluctuation in the longitudinal direction of the thick steel plate.
[0038]
On the other hand, in the comparative example, as shown in FIG. 7B, the temperature fluctuation in the longitudinal direction of the thick steel plate before heating continues as it is after the outlet of the first solenoid type induction heating apparatus.
[0039]
【The invention's effect】
As described above, according to the present invention, a thick steel plate is heated by passing through a plurality of solenoid type induction heating devices arranged in series at a predetermined interval, and each solenoid type induction heating device is passed in advance. The target temperature of the thick steel plate before setting is set, the deviation between the measured temperature of the thick steel plate measured before passing through each solenoid type induction heating device and the target temperature is obtained, and the temperature deviation is compensated forward or backward By compensating, it is possible to heat the steel sheet with high accuracy so that the average temperature becomes the target heat treatment temperature while performing uniform temperature in the thickness direction of the thick steel plate and managing the upper limit of the surface temperature.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a heat treatment facility for thick steel plates according to the present invention.
FIG. 2 is a diagram showing a temperature transition of a thick steel plate when the thick steel plate heat treatment facility of the present invention is used.
FIG. 3 is a diagram showing a first embodiment of a heat treatment method for a thick steel plate according to the present invention.
FIG. 4 is a diagram showing a second embodiment of the heat treatment method for thick steel plates according to the present invention.
FIG. 5 is a diagram showing a third embodiment of the heat treatment method for thick steel plates according to the present invention.
FIG. 6 is a view showing an arrangement example of a heat treatment apparatus for thick steel plates according to the present invention.
FIG. 7 is a diagram for explaining an example of a heat treatment method for a thick steel plate according to the present invention.
(A) It is a figure which shows the temperature transition of an Example.
(B) It is a figure which shows the temperature transition of a comparative example.
[Explanation of symbols]
1
Claims (5)
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001314160A JP3945212B2 (en) | 2001-10-11 | 2001-10-11 | Heat treatment apparatus and method for thick steel plate |
| EP01271125A EP1359230B1 (en) | 2000-12-18 | 2001-12-18 | Production method for steel plate and equipment therefor |
| PCT/JP2001/011086 WO2002050317A1 (en) | 2000-12-18 | 2001-12-18 | Production method for steel plate and equipment therefor |
| CNB018208444A CN100513589C (en) | 2000-12-18 | 2001-12-18 | Producing method for steel plate and equipment therefor |
| CN2008101885933A CN101463414B (en) | 2000-12-18 | 2001-12-18 | Production method for steel plate |
| DE60133936T DE60133936D1 (en) | 2000-12-18 | 2001-12-18 | METHOD FOR PRODUCING A STEEL PLATE AND EQUIPMENT THEREFOR |
| KR1020037007910A KR100549451B1 (en) | 2000-12-18 | 2001-12-18 | Production method for steel plate and equipment therefor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001314160A JP3945212B2 (en) | 2001-10-11 | 2001-10-11 | Heat treatment apparatus and method for thick steel plate |
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| Publication Number | Publication Date |
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| JP2003119516A JP2003119516A (en) | 2003-04-23 |
| JP3945212B2 true JP3945212B2 (en) | 2007-07-18 |
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| JP2001314160A Expired - Lifetime JP3945212B2 (en) | 2000-12-18 | 2001-10-11 | Heat treatment apparatus and method for thick steel plate |
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| JP4827383B2 (en) * | 2004-03-15 | 2011-11-30 | Ｊｆｅスチール株式会社 | Heat treatment method and apparatus for thick steel plate |
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