JP3979200B2

JP3979200B2 - Method for adjusting electrode elevation of DC arc heating device

Info

Publication number: JP3979200B2
Application number: JP2002193340A
Authority: JP
Inventors: 章夫鈴木
Original assignee: Daido Steel Co Ltd
Current assignee: Daido Steel Co Ltd
Priority date: 2002-07-02
Filing date: 2002-07-02
Publication date: 2007-09-19
Anticipated expiration: 2022-07-02
Also published as: JP2004039381A

Description

【０００１】
【発明の属する技術分野】
この発明は、電極に電力を供給することにより該電極から生ずる直流アークによって、被加熱物を加熱するよう構成した直流アーク加熱装置の電極昇降調節方法に関するものである。
【０００２】
【従来の技術】
上下に開口する鋳型(モールド)に溶鋼を鋳込み、該鋳型の下方に昇降可能に配設した昇降台のダミーヘッドに、鋳型内で冷却されて表面にシェルが形成された鋳片の下端を支持した状態で、該昇降台を所定速度で垂直に下降することで鋳型下部から鋳片を垂直に引抜いて、所定長さ寸法の鋳片を鋳造する垂直型鋳造装置が知られている。
【０００３】
前記垂直型鋳造装置においては、鋳込み完了後の静置凝固時に鋳型内の溶鋼を加熱することで、センターポロシティ、鋳片頭部キャビティ、中心偏析またはＶ状偏析等の内部欠陥の少ない高品質の鋳片を鋳造することができる。そこで、本願の出願人は、溶鋼の加熱装置として、直流アークを用いて溶鋼を加熱する直流アーク加熱装置を提案した。
【発明が解決しようとする課題】
前記鋳型内の溶鋼を加熱する際には、該溶鋼の温度を所定温度に保持することが重要になり、そのためには前記直流アーク加熱装置による加熱を安定させる必要があり、これを如何に行なうかが課題となっている。
【０００４】
【発明の目的】
この発明は、前述した従来の技術に内在している前記課題に鑑み、これを好適に解決するべく提案されたものであって、安定した加熱を行ない得る直流アーク加熱装置の電極昇降調節方法を提供することを目的とする。
【０００５】
【課題を解決するための手段】
前述した課題を解決し、所期の目的を好適に達成するため、本発明に係る直流アーク加熱装置の電極昇降調節方法は、
電極昇降装置で支持されて加熱室内を昇降可能な電極に、直流電源装置を介して電力を供給することで、該電極から発する直流アークにより加熱室内の被加熱物を加熱するよう構成した直流アーク加熱装置において、
前記加熱室内の温度を検出し、この検出温度と予め設定された目標温度との偏差を無くすために前記電極に供給する目標電力を求め、
前記目標電力に基づいて、予め求められている直流アークが安定する電力と電圧との関係データから目標電圧を求めると共に、該目標電圧と前記目標電力とから目標電流を求め、
前記直流電源装置から電極に供給されている検出電流が前記目標電流となるよう該直流電源装置を運転制御すると共に、このときの電極に供給されている検出電圧と前記目標電圧との偏差を無くすための目標電極位置を求め、
前記目標電極位置に前記電極が位置するように、前記電極昇降装置を制御して該電極を昇降調節するようにしたことを特徴とする。
【０００６】
前述した課題を解決し、所期の目的を好適に達成するため、本願の別の発明に係る直流アーク加熱装置の電極昇降調節方法は、
電極昇降装置で支持されて加熱室内を昇降可能な電極に、直流電源装置を介して電力を供給することで、該電極から発する直流アークにより加熱室内の被加熱物を加熱するよう構成した直流アーク加熱装置において、
前記加熱室内の温度を検出し、この検出温度と予め設定された目標温度との偏差を無くすために前記電極に供給する目標電力を求め、
前記目標電力に基づいて、予め求められている直流アークが安定する電力と電流との関係データから目標電流を求めると共に、該目標電流と前記目標電力とから目標電圧を求め、
前記直流電源装置から電極に供給されている検出電流が前記目標電流となるよう該直流電源装置を運転制御すると共に、このときの電極に供給されている検出電圧と前記目標電圧との偏差を無くすための目標電極位置を求め、
前記目標電極位置に前記電極が位置するように、前記電極昇降装置を制御して該電極を昇降調節するようにしたことを特徴とする。
【０００７】
【発明の実施の形態】
次に、本発明に係る直流アーク加熱装置の電極昇降調節方法につき、好適な実施例を挙げて、添付図面を参照しながら以下説明する。
【０００８】
【第１実施例】
図１は、第１実施例に係る直流アーク加熱装置を垂直型鋳造装置に採用した場合での概略構成を示すものであって、該垂直型鋳造装置の上下に開口する鋳型１０には、図示しないタンディッシュを介して溶鋼１２が鋳込まれ、該鋳型１０の下方に昇降可能に配設したダミーヘッド(図示せず)に、鋳型１０内で冷却されて表面にシェルが形成された鋳片１４の下端を支持した状態で、該ダミーヘッドを所定速度で垂直に下降することで鋳型下部から鋳片１４を垂直に引抜くよう構成される。前記鋳型１０の上方には、該鋳型１０の上部を覆い得る蓋部材１６が配設され、該蓋部材１６は、鋳型１０の上部から離間する待機位置と、鋳型１０の上部を覆う加熱位置とに移動可能に構成されると共に、鋳型１０の上部を該蓋部材１６で覆った際に、その内部に加熱室１８を画成するようになっている。
【０００９】
前記蓋部材１６の天井部には複数(第１実施例では２つ)の通孔１６ａが形成され、各通孔１６ａを介して直流アーク加熱装置２０を構成する電極２２が、加熱室１８内に夫々進退可能に挿入されるようになっている。そして、鋳型１０への被加熱物としての溶鋼１２の鋳込み完了後、静置凝固させる際の溶鋼加熱に際して蓋部材１６が加熱位置において鋳型１０の上部を覆った状態で、鋳型１０内の溶鋼１２と各電極２２との間に所定電圧を印加(電極２２に所定電力を供給)することで、該電極２２から放電する直流アークにより鋳型１０内の溶鋼１２を加熱するよう構成される。なお、溶鋼加熱等に際して該加熱室１８ａ内には、前記通孔１６ａを介してＡｒやＮ₂等の不活性ガスが供給され、室内を不活性ガス雰囲気とし得るようになっている。
【００１０】
前記直流アーク加熱装置２０は、電気モータＭやパルスジェネレータＰＧ等を有する電極昇降装置２４を、前記電極２２の本数と対応する数だけ備え、各電極昇降装置２４により対応する電極２２が夫々昇降可能に支持されている。なお、各電極昇降装置２４は、前記パルスジェネレータＰＧからの信号により電極位置(現在電極位置Ｈ₁)を監視し得る電極位置制御装置２６により運転制御される。また前記蓋部材１６には、前記加熱室１８内の温度を検出する熱電対等の温度センサ２８が配設され、該センサ２８により検出された検出温度Ｔ₁は、温度制御器３０に入力されるようになっている。この温度制御器３０には、温度設定器３２で予め設定された加熱室１８に求められる目標温度Ｔ₀が入力されるよう構成され、該温度制御器３０では、目標温度Ｔ₀と検出温度Ｔ₁との偏差から、その偏差を無くすために必要となる前記電極２２,２２への総投入電力量(目標電力Ｐ₀)を演算するよう設定される。そして、温度制御器３０で求められた目標電力Ｐ₀が、目標電圧変換器３４と目標電流演算器３６とに入力されるよう構成してある。
【００１１】
前記目標電圧変換器３４には、実機において予め同一の操業条件で実験した結果により得られた、前記電極２２から放電される直流アークが安定する電力と電圧との関係データ(図２に示す電力−電圧曲線)が設定記憶されており、該目標電圧変換器３４では、前記目標電力Ｐ₀と関係データとから第１の目標電圧Ｖ₀１を求めるようになっている。なお、第１実施例では２本の電極２２,２２を用いているため、この第１の目標電圧Ｖ₀１は２本の電極２２,２２に印加される総電圧値となる。また、前記目標電流演算器３６には目標電圧変換器３４で求められた第１の目標電圧Ｖ₀１が入力され、該目標電圧Ｖ₀１と前記目標電力Ｐ₀とから、該目標電流演算器３６は目標電流Ｉ₀を演算するよう構成される。前記操業条件とは、前記蓋部材１６の形状、加熱室１８の内部雰囲気、電極２２の使用本数、加熱する溶鋼１２の鋼種等である。
【００１２】
前記両電極２２,２２に電力を供給する電流制御機能付きの直流電源装置３８には、一方の電極２２のアーク電流を検出する電流検出器４０と、各電極２２,２２のアーク電圧を検出する電圧検出器４２,４２とが接続され、電流検出器４０で検出される検出電流(アーク電流)Ｉ₁が電流制御器４４に入力されるよう構成される。また電流制御器４４には、前記目標電流演算器３６で求められた目標電流Ｉ₀が入力されるようになっており、該電流制御器４４は、前記検出電流Ｉ₁が目標電流Ｉ₀となるように前記直流電源装置３８を運転制御するよう構成されている。
【００１３】
前記各電圧検出器４２で検出された検出電圧(アーク電圧)Ｖ₁は、対応する電圧制御器４６に入力されると共に、この電圧制御器４６には、前記第１の目標電圧Ｖ₀１を電極数で割った第２の目標電圧Ｖ₀２(電極２２の使用本数がＮ本であれば、Ｖ₀１／Ｎ)が入力されるようになっている。また各電圧制御器４６では、検出電圧Ｖ₁と第２の目標電圧Ｖ₀２との偏差を無くすための目標電極位置Ｈ₀が演算され、この求められた目標電極位置Ｈ₀が、対応する前記電極位置制御装置２６に入力されるよう構成される。そして、電極位置制御装置２６は、対応する電極２２が目標電極位置Ｈ₀となるよう対応する前記電極昇降装置２４を運転制御して該電極２２の昇降調節を行なうようになっている。
【００１４】
【第１実施例の作用】
次に、前述した第１実施例に係る直流アーク加熱装置の電極昇降調節方法の作用につき説明する。前記鋳型１０への溶鋼１２の鋳込み完了後に、前記蓋部材１６により鋳型１０の上部を覆うと共に前記加熱室１８に不活性ガスを供給した状態で、鋳型１０内の溶鋼１２を直流アーク加熱装置２０で加熱する。この溶鋼１２の加熱に際し、前記温度設定器３２には予め目標温度Ｔ₀が設定されており、この目標温度Ｔ₀と、前記温度センサ２８で検出される検出温度Ｔ₁とが、前記温度制御器３０に入力される。そして、温度制御器３０では、目標温度Ｔ₀と検出温度Ｔ₁との偏差を無くすために必要となる前記電極２２,２２に投入する目標電力Ｐ₀が求められる。なお、第１実施例のように鋳込み完了後の静置凝固時の鋳型１０内の溶鋼１２を加熱する場合では、前記加熱室１８の目標温度Ｔ₀は、蓋部材１６で覆われている鋳型１０内の溶鋼１２における湯面(メニスカス)の温度を固相線温度以上に保持し得る温度に設定される。
【００１５】
次に、前記目標電圧変換器３４において、予め設定記憶されている電力と電圧との関係データから、前記目標電力Ｐ₀に対応する第１の目標電圧Ｖ₀１が求められ、これが前記目標電流演算器３６に入力される。そして、この目標電流演算器３６では、前記第１の目標電圧Ｖ₀１と目標電力Ｐ₀とから目標電流Ｉ₀が求められ、これが前記電流制御器４４に入力される。電流制御器４４には、前記直流電源装置３８から電極２２に供給されて前記電流検出器４０で検出される検出電流Ｉ₁が入力されており、該検出電流Ｉ₁が前記目標電流Ｉ₀となるように電流制御器４４が直流電源装置３８を運転制御することで、前記電極２２,２２には目標電力Ｐ₀が供給される。
【００１６】
前記電流制御器４４により検出電流Ｉ₁が目標電流Ｉ₀となるよう前記直流電源装置３８を運転制御している間には、前記加熱室１８内の雰囲気、その他の条件の変化等によってアーク電圧、すなわち前記各電圧検出器４２で検出される検出電圧Ｖ₁が変化する。この検出電圧Ｖ₁は、対応する前記電圧制御器４６に入力されており、前記第１の目標電圧Ｖ₀１から得られる第２の目標電圧Ｖ₀２と該検出電圧Ｖ₁とが比較され、両者の偏差が無くなるような目標電極位置Ｈ₀が演算される。そして、この目標電極位置Ｈ₀に前記電極２２が位置するように、前記電極昇降装置２４が電極位置制御装置２６により運転制御(パルスジェネレータＰＧから入力される現在電極位置Ｈ₁に基づくフィードバック制御)され、電極２２と溶鋼１２の湯面との距離(ギャップ)が適正に調節され、前記加熱室１８の温度は目標温度Ｔ₀に保持される。すなわち、前記蓋部材１６で覆われている鋳型１０内の溶鋼１２における湯面の温度が固相線温度以上に保持され、該湯面が凝固するのは防止され、センターポロシティ、鋳片頭部キャビティ、中心偏析またはＶ状偏析等の内部欠陥の少ない高品質の鋳片１４を鋳造することができる。
【００１７】
前述したように、前記温度センサ２８で逐次検出される検出温度Ｔ₁と目標温度Ｔ₀との偏差を無くすために求められた目標電力Ｐ₀を実現するために、目標電圧Ｖ₀１,Ｖ₀２を基準として、アーク電流(検出電流Ｉ₁)とアーク電圧(検出電圧Ｖ₁)とが常に適切な値となるようフィードバック制御しているから、電極２２から放電される直流アークは安定し、加熱室１８を目標温度Ｔ₀に精度よく保持することができる。なお、前記目標電圧変換器３４に設定記憶される電力と電圧との関係データは、前記加熱室１８内の雰囲気や加熱する溶鋼１２の鋼種等の各種操業条件が異なる場合は、それに応じて予め実験により得られている対応する関係データが用いられる。すなわち、直流アーク加熱装置２０の制御系に、直流アークの複雑な安定条件を組み込む必要はなく、制御系の簡略化を図り得ると共に、操業条件の変更等にも柔軟に対応することができる。
【００１８】
【第２実施例】
図３は、第２実施例に係る直流アーク加熱装置の概略構成を示すものであって、その基本的な構成は第１実施例と同じであるので、異なる部分についてのみ説明すると共に、同一部材には同じ符号を付して示すものとする。
【００１９】
第２実施例の直流アーク加熱装置４８では、前記鋳型１０の上部を覆う蓋部材１６に内部画成される加熱室１８内に進退可能に挿入される１本の電極２２により、溶鋼１２を加熱するよう構成される。前記温度制御器３０で求められた目標電力Ｐ₀が、目標電流変換器５０に入力されるよう構成される。この目標電流変換器５０には、実機において予め同一の操業条件で実験した結果により得られた、前記電極２２から放電される直流アークが安定する電力と電流との関係データ(図４に示す電力−電流曲線)が設定記憶されており、該目標電流変換器５０では、前記目標電力Ｐ₀と関係データとから目標電流Ｉ₀を求めるようになっている。そして、この目標電流Ｉ₀が入力される前記電流制御器４４は、前記直流電源装置３８に接続された前記電流検出器４０で検出される検出電流Ｉ₁が目標電流Ｉ₀となるように直流電源装置３８を運転制御するよう構成される。
【００２０】
前記温度制御器３０で求められた目標電力Ｐ₀と、前記目標電流変換器５０で求められた目標電流Ｉ₀とが、目標電圧演算器５２に入力され、ここで目標電圧Ｖ₀が演算されるようになっている。そして、前記直流電源装置３８に接続された前記電圧検出器４２で検出される検出電圧Ｖ₁と前記目標電圧Ｖ₀とが電圧制御器４６に入力され、該電圧制御器４６が目標電極位置Ｈ₀を演算し、この求められた目標電極位置Ｈ₀に基づいて、前記電極位置制御装置２６が電極昇降装置２４を運転制御するよう構成される。
【００２１】
【第２実施例の作用】
次に、前述した第２実施例に係る直流アーク加熱装置の電極昇降調節方法の作用につき、第１実施例と異なる部分についてのみ説明する。鋳込み完了後の前記鋳型１０内の溶鋼１２を直流アーク加熱装置４８で加熱するに際し、前記目標温度Ｔ₀と検出温度Ｔ₁とから求められた目標電力Ｐ₀が、前記目標電流変換器５０に入力される。この目標電流変換器５０において、予め設定記憶されている電力と電流との関係データから、前記目標電力Ｐ₀に対応する目標電流Ｉ₀が求められ、これが前記電流制御器４４に入力される。電流制御器４４には、前記電流検出器４０で検出される検出電流Ｉ₁が入力されており、該検出電流Ｉ₁が目標電流Ｉ₀となるように前記直流電源装置３８を運転制御することで、前記電極２２には目標電力Ｐ₀が供給される。
【００２２】
また、前記目標電力Ｐ₀と目標電流Ｉ₀とが、前記目標電圧演算器５２に入力されることで、目標電圧Ｖ₀が求められ、これが電圧制御器４６に入力される。そしてこの電圧制御器４６では、前記電圧検出器４２で検出される検出電圧Ｖ₁と目標電圧Ｖ₀とから目標電極位置Ｈ₀が求められる。そして、この目標電極位置Ｈ₀に電極２２が位置するように、前記電極昇降装置２４が電極位置制御装置２６により運転制御されることで、第１実施例と同様に前記加熱室１８の温度は目標温度Ｔ₀に保持され、内部欠陥の少ない高品質の鋳片が鋳造される。
【００２３】
第２実施例においても、前記温度センサ２８で逐次検出される検出温度Ｔ₁と目標温度Ｔ₀との偏差を無くすために求められた目標電力Ｐ₀を実現するために、目標電流Ｉ₀を基準としてアーク電流とアーク電圧とが常に適切な値となるようフィードバック制御しているから、電極２２から放電される直流アークは安定し、加熱室１８を目標温度Ｔ₀に精度よく保持することができる。
【００２４】
【変更例】
第１実施例においての電極の使用本数は２本に限定されず、１本または３本以上であってもよく、また第２実施例においての電極の使用本数も１本に限定されず、２本以上であってもよい。例えば、第１実施例のように目標電圧を基準として制御する場合において１本の電極２２を用いる構成では、１本の電極２２による電力と電圧との関係データから目標電圧Ｖ₀が求められ、該目標電圧Ｖ₀を基に目標電流Ｉ₀と目標電極位置Ｈ₀とが求められる。また、第２実施例のように目標電流を基準として制御する場合においてＮ数本の電極２２を用いる構成では、Ｎ数本の電極２２による電力と電流との関係データから第１の目標電流Ｉ₀１が求められ、該目標電流Ｉ₀１の１／Ｎとなる第２の目標電流Ｉ₀２を基に、目標電圧Ｖ₀と目標電極位置Ｈ₀とが求められる。
【００２５】
両実施例では、鋳型に鋳込まれている溶鋼を加熱する場合で説明したが、前記加熱室を予熱する場合にも本願の電極昇降調節方法を採用し得る。すなわち、例えばカーボンを材質とする受電板に蓋部材を載置して熱加室を画成し、該加熱室に不活性ガスを供給した状態で、受電板と電極との間に所定電圧を印加することで、電極から放電する直流アークにより加熱室、すなわち蓋部材を所定温度まで予熱する場合における直流アーク加熱装置の電極昇降調節方法として採用し得る。更に、実施例では直流アーク加熱装置を垂直型鋳造装置に採用した場合で説明したが、金属材料の溶融炉等の加熱装置として直流アーク加熱装置を採用してもよく、この場合に本願の電極昇降調節方法を用いることができる。なお、この場合の加熱室は炉内となり、また被加熱物は、炉内に装入された金属材料となる。
【００２６】
【発明の効果】
以上説明した如く、本発明に係る直流アーク加熱装置の電極昇降調節方法によれば、目標温度と検出温度とから演算される目標電力を実現するため、電流と電圧との２つのパラメータを自動的に適切な値に制御することで、安定した直流アークにより被加熱物を加熱することができる。また実機により同一の操業条件で実験して求められた電力と電圧または電力と電流との関係データを用いて目標電圧または目標電流を求めるようにしたから、安定した直流アークによる加熱が容易に実現できる。
【図面の簡単な説明】
【図１】本発明の好適な第１実施例に係る直流アーク加熱装置を示す概略構成図である。
【図２】電力−電圧曲線を示すグラフ図である。
【図３】本発明の好適な第２実施例に係る直流アーク加熱装置を示す概略構成図である。
【図４】電力−電流曲線を示すグラフ図である。
【符号の説明】
１２溶鋼(被加熱物)
１８加熱室
２２電極
２４電極昇降装置
３８直流電源装置
Ｔ₀ 目標温度
Ｔ₁ 検出温度
Ｐ₀ 目標電力
Ｖ₀ 目標電圧
Ｖ₀１第１の目標電圧
Ｖ₀２第２の目標電圧
Ｖ₁ 検出電圧
Ｉ₀ 目標電流
Ｉ₁ 検出電流
Ｈ₀ 目標電極位置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode elevation adjustment method for a DC arc heating apparatus configured to heat an object to be heated by a DC arc generated from the electrode by supplying electric power to the electrode .
[0002]
[Prior art]
Molten steel is cast into a mold (mold) that opens up and down, and the lower end of the slab that is cooled in the mold and has a shell formed on the surface is supported by a dummy head that is arranged so that it can be raised and lowered below the mold. In such a state, a vertical casting apparatus is known in which the slab is vertically drawn at a predetermined speed to pull the slab vertically from the lower part of the mold to cast a slab having a predetermined length.
[0003]
In the vertical casting apparatus, the molten steel in the mold is heated at the time of stationary solidification after the casting is completed, so that a high quality casting with less internal defects such as center porosity, slab head cavity, center segregation or V-shaped segregation. Pieces can be cast. Therefore, the applicant of the present application has proposed a direct current arc heating device that heats molten steel using a direct current arc as a molten steel heating device.
[Problems to be solved by the invention]
When heating the molten steel in the mold, it is important to maintain the temperature of the molten steel at a predetermined temperature. For this purpose, it is necessary to stabilize the heating by the DC arc heating device, and how to do this. Is a problem.
[0004]
OBJECT OF THE INVENTION
In view of the above-mentioned problems inherent in the prior art described above, the present invention has been proposed to suitably solve this problem, and provides a method for adjusting the electrode elevation of a DC arc heating apparatus capable of performing stable heating. The purpose is to provide.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the desired purpose suitably, the electrode elevation adjustment method of the DC arc heating device according to the present invention is:
A direct current arc configured to heat an object to be heated in a heating chamber by a direct current arc generated from the electrode by supplying electric power to the electrode supported by the electrode lifting device and capable of moving up and down in the heating chamber via a direct current power supply device. In the heating device,
Detecting a temperature in the heating chamber, and obtaining a target power to be supplied to the electrode in order to eliminate a deviation between the detected temperature and a preset target temperature,
Based on the target power, the target voltage is determined from the relational data between the power and voltage at which the DC arc obtained in advance is stable, and the target current is determined from the target voltage and the target power,
The DC power supply is operated and controlled so that the detected current supplied from the DC power supply to the electrode becomes the target current, and the deviation between the detected voltage supplied to the electrode and the target voltage at this time is eliminated. The target electrode position for
The electrode lifting / lowering device is controlled so as to move the electrode up and down so that the electrode is positioned at the target electrode position.
[0006]
In order to solve the above-mentioned problem and to achieve the intended purpose suitably, the electrode elevation adjustment method of the DC arc heating device according to another invention of the present application is:
A direct current arc configured to heat an object to be heated in a heating chamber by a direct current arc generated from the electrode by supplying electric power to the electrode supported by the electrode lifting device and capable of moving up and down in the heating chamber via a direct current power supply device. In the heating device,
Detecting a temperature in the heating chamber, and obtaining a target power to be supplied to the electrode in order to eliminate a deviation between the detected temperature and a preset target temperature,
Based on the target power, the target current is determined from the relationship data between the power and current that stabilizes the DC arc that is determined in advance, and the target voltage is determined from the target current and the target power,
The DC power supply is operated and controlled so that the detected current supplied from the DC power supply to the electrode becomes the target current, and the deviation between the detected voltage supplied to the electrode and the target voltage at this time is eliminated. The target electrode position for
The electrode lifting / lowering device is controlled so as to move the electrode up and down so that the electrode is positioned at the target electrode position.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, a preferred embodiment of the method for adjusting an electrode elevation of a DC arc heating apparatus according to the present invention will be described below with reference to the accompanying drawings.
[0008]
[First embodiment]
FIG. 1 shows a schematic configuration when the direct-current arc heating apparatus according to the first embodiment is adopted in a vertical casting apparatus, and a mold 10 opened up and down of the vertical casting apparatus is shown in FIG. The molten steel 12 is cast through a tundish not to be cast, and a slab having a shell formed on the surface thereof is cooled in the mold 10 by a dummy head (not shown) disposed below the mold 10 so as to be movable up and down. In a state where the lower end of 14 is supported, the slab 14 is vertically pulled out from the lower part of the mold by vertically lowering the dummy head at a predetermined speed. A lid member 16 that can cover the top of the mold 10 is disposed above the mold 10, and the lid member 16 includes a standby position that is separated from the top of the mold 10, and a heating position that covers the top of the mold 10. When the upper part of the mold 10 is covered with the lid member 16, a heating chamber 18 is defined therein.
[0009]
A plurality of (two in the first embodiment) through holes 16 a are formed in the ceiling portion of the lid member 16, and the electrodes 22 constituting the DC arc heating device 20 are formed in the heating chamber 18 through the respective through holes 16 a. Each is inserted so that it can be advanced and retracted. Then, after the casting of the molten steel 12 as an object to be heated into the mold 10 is completed, the molten steel 12 in the mold 10 is covered with the lid member 16 covering the upper portion of the mold 10 at the heating position when the molten steel is heated for stationary solidification. When a predetermined voltage is applied between the electrode 22 and each electrode 22 (a predetermined power is supplied to the electrode 22), the molten steel 12 in the mold 10 is heated by a DC arc discharged from the electrode 22. It should be noted that an inert gas such as Ar or N ₂ is supplied into the heating chamber 18a through the through hole 16a when the molten steel is heated, so that the interior of the chamber can be made an inert gas atmosphere.
[0010]
The DC arc heating device 20 includes electrode lifting / lowering devices 24 having electric motors M, pulse generators PG, etc., corresponding to the number of the electrodes 22, and the corresponding electrodes 22 can be lifted / lowered by the respective electrode lifting / lowering devices 24. It is supported by. Each electrode lifting device 24 is operated and controlled by an electrode position control device 26 that can monitor the electrode position (current electrode position H ₁ ) based on a signal from the pulse generator PG. The lid member 16 is provided with a temperature sensor 28 such as a thermocouple for detecting the temperature in the heating chamber 18, and the detected temperature T ₁ detected by the sensor 28 is input to the temperature controller 30. It is like that. The temperature controller 30 is configured to receive the target temperature T ₀ required for the heating chamber 18 set in advance by the temperature setter 32. The temperature controller 30 receives the target temperature T ₀ and the detected temperature T. _From the deviation from ₁ , it is set so as to calculate the total input electric power (target electric power P ₀ ) to the electrodes 22 and 22 required to eliminate the deviation. The target power P ₀ obtained by the temperature controller 30 is input to the target voltage converter 34 and the target current calculator 36.
[0011]
In the target voltage converter 34, relational data (power shown in FIG. 2) between the power and voltage at which the DC arc discharged from the electrode 22 is stabilized, obtained as a result of an experiment performed in advance in the actual machine under the same operating conditions. -Voltage curve) is set and stored, and the target voltage converter 34 obtains the first target voltage V ₀ 1 from the target power P ₀ and related data. In the first embodiment, since the two electrodes 22 and 22 are used, the first target voltage V ₀ 1 is a total voltage value applied to the two electrodes 22 and 22. The target current calculator 36 receives the first target voltage V ₀ 1 obtained by the target voltage converter 34 and calculates the target current from the target voltage V ₀ 1 and the target power P _0. Unit 36 is configured to calculate target current I ₀ . The operating conditions include the shape of the lid member 16, the internal atmosphere of the heating chamber 18, the number of electrodes 22 used, the steel type of the molten steel 12 to be heated, and the like.
[0012]
The DC power supply 38 with a current control function for supplying power to the electrodes 22 and 22 includes a current detector 40 that detects the arc current of one electrode 22 and the arc voltage of each electrode 22 and 22. The voltage detectors 42 and 42 are connected to each other, and a detection current (arc current) I ₁ detected by the current detector 40 is input to the current controller 44. Further, the target current I ₀ obtained by the target current calculator 36 is inputted to the current controller 44, and the current controller 44 determines that the detected current I ₁ is the target current I ₀ . Thus, the DC power supply device 38 is configured to control the operation.
[0013]
The detected voltage (arc voltage) V ₁ detected by each voltage detector 42 is input to the corresponding voltage controller 46, and the first target voltage V ₀ 1 is input to the voltage controller 46. A second target voltage V ₀ 2 divided by the number of electrodes (V ₀ 1 / N if the number of electrodes 22 used is N) is input. Further, each voltage controller 46 calculates a target electrode position H ₀ for eliminating a deviation between the detected voltage V ₁ and the second target voltage V ₀ 2, and the obtained target electrode position H ₀ corresponds. The electrode position controller 26 is configured to be input. The electrode position control device 26 controls the operation of the corresponding electrode lifting / lowering device 24 so that the corresponding electrode 22 becomes the target electrode position H ₀ , thereby adjusting the lifting / lowering of the electrode 22.
[0014]
[Operation of the first embodiment]
Next, the operation of the electrode elevation adjustment method of the DC arc heating apparatus according to the first embodiment will be described. After the casting of the molten steel 12 into the mold 10 is completed, the lid member 16 covers the upper portion of the mold 10 and supplies the inert gas to the heating chamber 18, and the molten steel 12 in the mold 10 is subjected to a DC arc heating device 20. Heat with. When the molten steel 12 is heated, a target temperature T ₀ is set in the temperature setting device 32 in advance, and the target temperature T ₀ and the detected temperature T ₁ detected by the temperature sensor 28 are used for the temperature control. Is input to the device 30. Then, the temperature controller 30 obtains the target power P ₀ to be input to the electrodes 22 and 22 necessary for eliminating the deviation between the target temperature T ₀ and the detected temperature T ₁ . When the molten steel 12 in the mold 10 at the time of stationary solidification after completion of casting is heated as in the first embodiment, the target temperature T ₀ of the heating chamber 18 is the mold covered with the lid member 16. The temperature of the molten metal surface (meniscus) in the molten steel 12 in 10 is set to a temperature at which the temperature can be maintained above the solidus temperature.
[0015]
Next, the target voltage converter 34 obtains the first target voltage V ₀ 1 corresponding to the target power P ₀ from the relation data between the power and the voltage set and stored in advance, and this is the target current. Input to the calculator 36. The target current calculator 36 obtains a target current I ₀ from the first target voltage V ₀ 1 and the target power P _0, and this is input to the current controller 44. The current controller 44 is supplied with a detection current I ₁ supplied to the electrode 22 from the DC power supply device 38 and detected by the current detector 40, and the detection current I ₁ is the target current I ₀ . The current controller 44 controls the operation of the DC power supply device 38 so that the target power P ₀ is supplied to the electrodes 22 and 22.
[0016]
While the operation of the DC power supply 38 is controlled by the current controller 44 so that the detected current I ₁ becomes the target current I ₀ , the arc voltage is caused by changes in the atmosphere in the heating chamber 18 and other conditions. That is, the detection voltage V ₁ detected by each voltage detector 42 changes. This detection voltage V ₁ is input to the corresponding voltage controller 46, and the second target voltage V ₀ 2 obtained from the first target voltage V ₀ 1 is compared with the detection voltage V _1. The target electrode position H ₀ is calculated such that there is no deviation between the two. Then, the electrode lifting device 24 is controlled by the electrode position control device 26 so that the electrode 22 is positioned at the target electrode position H ₀ (feedback control based on the current electrode position H ₁ input from the pulse generator PG). Then, the distance (gap) between the electrode 22 and the molten steel 12 is appropriately adjusted, and the temperature of the heating chamber 18 is maintained at the target temperature T ₀ . That is, the temperature of the molten metal surface in the molten steel 12 in the mold 10 covered with the lid member 16 is maintained at a temperature equal to or higher than the solidus temperature, and the molten metal surface is prevented from solidifying. Further, it is possible to cast a high quality slab 14 having few internal defects such as center segregation or V-shaped segregation.
[0017]
As described above, in order to realize the target power P ₀ obtained in order to eliminate the deviation between the detected temperature T ₁ sequentially detected by the temperature sensor 28 and the target temperature T ₀ , the target voltages V ₀ 1, V _{Since the} feedback control is performed so that the arc current (detection current I ₁ ) and the arc voltage (detection voltage V ₁ ) always have appropriate values with reference to 02, the DC arc discharged from the electrode 22 is stable. The heating chamber 18 can be accurately maintained at the target temperature T ₀ . It should be noted that the relational data between the electric power and the voltage set and stored in the target voltage converter 34 is different in advance if various operating conditions such as the atmosphere in the heating chamber 18 and the steel type of the molten steel 12 to be heated are different. Corresponding relational data obtained from experiments is used. That is, it is not necessary to incorporate complicated stability conditions for the DC arc in the control system of the DC arc heating device 20, and the control system can be simplified, and changes in operating conditions can be flexibly handled.
[0018]
[Second embodiment]
FIG. 3 shows a schematic configuration of the direct-current arc heating apparatus according to the second embodiment, and the basic configuration is the same as that of the first embodiment. Are denoted by the same reference numerals.
[0019]
In the DC arc heating device 48 of the second embodiment, the molten steel 12 is heated by one electrode 22 that is movably inserted into a heating chamber 18 defined in the lid member 16 that covers the upper portion of the mold 10. Configured to do. The target power P ₀ obtained by the temperature controller 30 is configured to be input to the target current converter 50. In this target current converter 50, the relational data (the power shown in FIG. 4) between the power and current that stabilizes the DC arc discharged from the electrode 22 obtained as a result of an experiment in advance under the same operating conditions in an actual machine. −current curve) is set and stored, and the target current converter 50 obtains the target current I ₀ from the target power P ₀ and related data. Then, the current controller 44 to which the target current I ₀ is input is a direct current so that the detected current I ₁ detected by the current detector 40 connected to the direct current power supply device 38 becomes the target current I _0. The power supply device 38 is configured to control the operation.
[0020]
The target power P ₀ obtained by the temperature controller 30 and the target current I ₀ obtained by the target current converter 50 are input to the target voltage calculator 52, where the target voltage V ₀ is calculated. It has become so. Then, the detection voltage V ₁ detected by the voltage detector 42 connected to the DC power supply device 38 and the target voltage V ₀ are input to the voltage controller 46, and the voltage controller 46 is connected to the target electrode position H. _The electrode position control device 26 is configured to control the operation of the electrode lifting device 24 based on the calculated target electrode position H ₀ .
[0021]
[Operation of the second embodiment]
Next, only the differences from the first embodiment will be described with respect to the operation of the electrode elevation adjustment method of the DC arc heating apparatus according to the second embodiment described above. When the molten steel 12 in the mold 10 after the casting is heated by the DC arc heating device 48, the target power P ₀ obtained from the target temperature T ₀ and the detected temperature T ₁ is supplied to the target current converter 50. Entered. In this target current converter 50, from the relationship data between the power and current which is previously set and stored, the target current I ₀ corresponding to the target power P ₀ is obtained, which is input to the current controller 44. The current controller 44 receives the detection current I ₁ detected by the current detector 40 and controls the operation of the DC power supply 38 so that the detection current I ₁ becomes the target current I _0. Thus, the target power P ₀ is supplied to the electrode 22.
[0022]
Further, the target power P ₀ and the target current I ₀ are input to the target voltage calculator 52, thereby obtaining a target voltage V ₀ , which is input to the voltage controller 46. In the voltage controller 46, the target electrode position H ₀ is obtained from the detection voltage V ₁ detected by the voltage detector 42 and the target voltage V ₀ . Then, the electrode lifting device 24 is operated and controlled by the electrode position control device 26 so that the electrode 22 is positioned at the target electrode position H ₀ , so that the temperature of the heating chamber 18 is the same as in the first embodiment. A high-quality slab that is maintained at the target temperature T _{0 and} has few internal defects is cast.
[0023]
Also in the second embodiment, in order to realize the target power P ₀ obtained to eliminate the deviation between the detected temperature T ₁ successively detected by the temperature sensor 28 and the target temperature T ₀ , the target current I ₀ is set to Since the feedback control is performed so that the arc current and the arc voltage always have appropriate values as a reference, the DC arc discharged from the electrode 22 is stable, and the heating chamber 18 can be accurately maintained at the target temperature T _0. it can.
[0024]
[Example of change]
The number of electrodes used in the first embodiment is not limited to two, but may be one or three or more, and the number of electrodes used in the second embodiment is not limited to one, but 2 It may be more than this. For example, in the case of controlling using the target voltage as a reference as in the first embodiment, in the configuration using one electrode 22, the target voltage V ₀ is obtained from the relational data between the power and voltage of the one electrode 22, Based on the target voltage V ₀ , the target current I ₀ and the target electrode position H ₀ are obtained. Further, when the control is performed based on the target current as in the second embodiment, in the configuration using N number of electrodes 22, the first target current I is obtained from the relational data between the power and current of the N number of electrodes 22. ₀ 1 is obtained, and the target voltage V ₀ and the target electrode position H ₀ are obtained based on the second target current I ₀ 2 that is 1 / N of the target current I ₀ 1.
[0025]
In both the embodiments, the case where the molten steel cast in the mold is heated has been described. However, the electrode lifting / lowering adjustment method of the present application can also be adopted when the heating chamber is preheated. That is, for example, a lid member is placed on a power receiving plate made of carbon to define a heating chamber, and an inert gas is supplied to the heating chamber, and a predetermined voltage is applied between the power receiving plate and the electrode. When applied, the heating chamber, that is, the lid member is preheated to a predetermined temperature by a DC arc discharged from the electrode, and can be employed as an electrode elevation adjustment method for a DC arc heating device. Further, in the examples, the case where the DC arc heating device is employed in the vertical casting device has been described. However, a DC arc heating device may be employed as a heating device for a metal material melting furnace, in which case the electrode of the present application is used. An elevation adjustment method can be used. In this case, the heating chamber is in the furnace, and the object to be heated is a metal material charged in the furnace.
[0026]
【The invention's effect】
As described above, according to the electrode elevation adjustment method of the DC arc heating apparatus according to the present invention, in order to realize the target power calculated from the target temperature and the detected temperature, two parameters of current and voltage are automatically set. By controlling to an appropriate value, the object to be heated can be heated by a stable DC arc. In addition, since the target voltage or target current is obtained using the relationship data between power and voltage or power and current obtained by experimenting under the same operating conditions with an actual machine, stable heating with a DC arc is easily realized. it can.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a DC arc heating apparatus according to a first preferred embodiment of the present invention.
FIG. 2 is a graph showing a power-voltage curve.
FIG. 3 is a schematic configuration diagram showing a DC arc heating apparatus according to a second preferred embodiment of the present invention.
FIG. 4 is a graph showing a power-current curve.
[Explanation of symbols]
12 Molten steel (object to be heated)
18 Heating chamber 22 Electrode 24 Electrode lifting device 38 DC power supply device T ₀ target temperature T ₁ detection temperature P ₀ target power V ₀ target voltage V ₀ 1 first target voltage V ₀ 2 second target voltage V ₁ detection voltage I ₀ target current I ₁ detection current H ₀ target electrode position

Claims

Direct current generated from the electrode (22) is supplied to the electrode (22) supported by the electrode lifting device (24) and can be moved up and down in the heating chamber (18) via the DC power supply device (38). In a DC arc heating apparatus configured to heat an object to be heated (12) in a heating chamber (18) by an arc,
The temperature in the heating chamber (18) is detected, and the target power (P) supplied to the electrode (22) to eliminate the deviation between the detected temperature (T ₁ ) and the preset target temperature (T ₀ ). ₀ )
Based on the target power (P ₀ ), the target voltage (V ₀ ) is obtained from the relationship data between the power and voltage at which the DC arc that is obtained in advance is stabilized, and the target voltage (V ₀ ) and the target power From (P ₀ ), the target current (I ₀ ) is obtained,
The DC power supply (38) is operated and controlled so that the detected current (I ₁ ) supplied from the DC power supply (38) to the electrode (22) becomes the target current (I ₀ ). Find the target electrode position (H ₀ ) to eliminate the deviation between the detection voltage (V ₁ ) supplied to the electrode (22) and the target voltage (V ₀ ),
A direct current arc characterized in that the electrode (22) is controlled to be moved up and down by controlling the electrode lifting device (24) so that the electrode (22) is positioned at the target electrode position (H ₀ ). A method for adjusting the elevation of the electrode of the heating device.

2. The method for adjusting an electrode ascending / descending of a DC arc heating apparatus according to claim 1, wherein the relational data between the electric power and the voltage is obtained by an experiment with an actual machine under the same operating conditions.

Direct current generated from the electrode (22) is supplied to the electrode (22) supported by the electrode lifting device (24) and can be moved up and down in the heating chamber (18) via the DC power supply device (38). In a DC arc heating apparatus configured to heat an object to be heated (12) in a heating chamber (18) by an arc,
The temperature in the heating chamber (18) is detected, and the target power (P) supplied to the electrode (22) to eliminate the deviation between the detected temperature (T ₁ ) and the preset target temperature (T ₀ ). ₀ )
Based on the target power (P ₀ ), the target current (I ₀ ) is obtained from the relationship data between the power and current that stabilizes the DC arc that is obtained in advance, and the target current (I ₀ ) and the target power Calculate the target voltage (V ₀ ) from (P ₀ )
The DC power supply (38) is operated and controlled so that the detected current (I ₁ ) supplied from the DC power supply (38) to the electrode (22) becomes the target current (I ₀ ). Find the target electrode position (H ₀ ) to eliminate the deviation between the detection voltage (V ₁ ) supplied to the electrode (22) and the target voltage (V ₀ ),
A direct current arc characterized in that the electrode (22) is controlled to be moved up and down by controlling the electrode lifting device (24) so that the electrode (22) is positioned at the target electrode position (H ₀ ). A method for adjusting the elevation of the electrode of the heating device.

4. The method for adjusting an electrode ascending / descending of a DC arc heating apparatus according to claim 3, wherein the relational data between the electric power and the electric current is obtained by an experiment with an actual machine under the same operating conditions.