JP3878309B2 - Molten metal level measurement method and molten metal level meter in continuous casting of molten metal - Google Patents
Molten metal level measurement method and molten metal level meter in continuous casting of molten metal Download PDFInfo
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Description
【0001】
【発明の属する技術分野】
本発明は、溶融金属の連続鋳造における溶融金属の連続鋳造時における鋳型中の溶融金属湯面レベル位置測定方法とそれに使用するレベル計に関するものである。
【0002】
【従来の技術】
一般に溶融金属の連続鋳造においては、パウダーが鋳型内溶融金属プール上面に供給され、溶融金属からの熱で溶解したパウダーは上下に振動する鋳型壁と、一定速度で引き抜かれる凝固シェルの相対運動によって、これらの間に流入するが、この流入時に発生する動圧によりメニスカスや凝固シェル先端が変形し、しかもこの変形は鋳型オッシレーションの周期で繰り返されるために、鋳片表面にはオッシレーションマークと呼ばれる周期的な皺が形成される。しかし、この皺の深さが深い場合には、鋳片表面疵欠陥に繋がる他、鋼種によっては特定の元素のみがこのオッシレーションマーク谷部に偏析したり、気泡、介在物の捕捉が増加し、歩留まり低下の原因となっている。
【0003】
一方、ビレットや小断面積を有する鋳片の連続鋳造においては、上記パウダーに替わってレプシードオイルが使用されている。このレプシードオイルはメニスカスにおいて燃焼し、グラファイトとなって凝固シェルが鋳型壁に焼きつくことを防止するものの、鋳造された鋳片表面に規則的に生成した明瞭なオッシレーションマークを得ることは困難で、鋳造操業や鋳片の品質安定性は、上記パウダーを用いた鋳造に比べて劣っている。
【0004】
このように、初期凝固を制御する方法としては、特開昭52−32824号公報に記載されるように、溶融金属を潤滑剤と共に一定周期で振動する水冷鋳型に注入し、連続的に下方に引き抜く連続鋳造法で、鋳型周りに設けた電磁コイルに交流電流を連続的に通電し、交流磁場によって発生する電磁力を利用して鋳型内溶融金属のメニスカスに電磁力を付与してメニスカス部を彎曲させて鋳片の表面性状を改善する方法が開示されている。また、特開昭64−83348号公報には、電磁コイルによって鋳型内の溶融金属に電磁力を与える際に、交流磁場をパルス状に付与することによって電磁力を間欠的に印加するパウダーキャスティング法で更に鋳片の表面性状を改善する方法が開示されている。また、再公表平8−805926号公報には、電磁力を付与するために交流電流の振幅に、鋳型振動と同じ周波数の強弱をつけ、鋳型振動周波数(fm)と交流磁場周波数(fp)とを0.69≦ln(fp/fm)≦9.9、ただし、lnは定数、の範囲内に設定することで安定したメニスカスを生成させ、鋳片の表面性状効果を更に安定して得る連続鋳造方法が開示されている。
【0005】
また、溶融金属のレベル検出方法については、従来より浮き子を利用する方法、光学的(光電変換)手法、超音波、放射線を利用する方法、漬積電極式、サーモカップル方式、電磁誘導方式等の様々な方式が開発、実施されている。さらには、特開平3−122526号公報、特開平3−138536号公報、特開平4−187355号公報および特開平4−238661号公報に開示されているような、溶融金属中で発生する渦電流の大小による受信コイルのインピーダンス変化を位相変化として測定する方法が開発されている。また、特開平4−238661号公報には、複数個の検出器で湯面レベルの変動範囲を分割測定し、検出器の切替えによる測定値の不連続性を抑制する方法も開発されている。
【0006】
【発明が解決しようとする課題】
しかしながら、これら従来技術を実際に電磁誘導加熱装置を設置した連続鋳造装置で実現する場合、鋳型内溶融金属の湯面レベルを精度よく検知できないという問題があった。この湯面レベル検知の精度が劣化していくと湯面レベル制御が困難になり、溶融金属のメニスカスの安定成形も難しくなり、結果的に良好な鋳片の表面性状確保ができなくなるという問題があった。
【0007】
一方、連続鋳造装置に使用される湯面レベル検知手段として、前述したような交流磁場による電磁誘導現象を応用した渦流式湯面レベル計が良く使用されている。また、他の手段としては鋳型に埋設した熱電対を利用する方法や、γ線を用いた透過型センサー等があるが、測定精度や応答性の点で渦流センサーが最も優れている観点から殆どの連続鋳造装置で使用されている。しかしながら、電磁コイルを使用する限りにおいては、電磁コイルから発生する交流磁場が、渦流式湯面レベルセンサーに対してノイズとして作用し、正確な湯面レベル検知が行えず、しかも測定精度が悪化していくという大きな問題を引き起こしている。例えば、1,000(Gauss) 以上の強度で周波数200Hzの連続電磁誘導鋳造における磁界中で使用した場合には信号出力電圧が飽和して測定不能となったり、パルス電磁誘導鋳造における磁界中でも磁界ONの時には飽和して、そのままでは溶融金属の湯面れべるが測定できないという深刻な問題が発生している。
【0008】
【課題を解決するための手段】
そこで、本発明者らは、パルス磁場を発生させて鋳片の表面性状を改善するような連続鋳造装置においては、渦流式湯面レベルセンサーに対して、パルス付与期(ON期)には強いノイズが作用するが、パルス付与中断期(OFF期)には殆どノイズが発生しないことに着目し、パルスON期とパルスOFF期を周期的に繰り返し、渦流式湯面レベル計または鋳型内蔵式レベル計の信号処理装置に入力し、この信号処理装置内でパルスOFF期にのみ湯面レベルを検知し、パルスON期には検知しないようにすることで、電磁コイルから発生する交流磁場ノイズの影響を受けることなく、安定して精度高い溶融金属の湯面レベル検知が可能になったものであり、その要旨は次の通りである。
【0009】
(1)鋳型を取り囲むように配置した電磁コイルを制御部によって、該電磁コイルの電流を一定周期で通電(ON)し、その通電中にOFF時間を任意の回数設けて、次いで一定周期で通電する操作を繰り返して、前記鋳型内の溶融金属に電磁力を付与しながら該溶融金属を鋳造する連続鋳造装置に用いる、前記鋳型内溶融金属の湯面レベルを検知するための湯面レベル測定方法であって、前記制御部の通電のON/OFFを表すマスキング信号に基づいて、OFF時間のみ渦流式レベル計又は鋳型内蔵式湯面レベル計を測定・出力させることにより湯面レベルを測定することを特徴とする連続鋳造における溶融金属湯面レベル測定方法。
【0010】
(2)鋳型を取り囲むように配置した電磁コイルを制御部によって、該電磁コイルの電流を一定周期で通電し、その通電中にOFF時間を任意の回数設けて、次いで一定周期で通電する操作を繰り返して、前記鋳型内の溶融金属に電磁力を付与しながら該溶融金属を鋳造する連続鋳造装置に用いる、前記鋳型内溶融金属の湯面レベルを検知するための湯面レベル計であって、渦流式又は鋳型内蔵式の湯面レベルセンサーと、該湯面レベルセンサーの出力を検波する検波器、及び前記制御部からの通電のON/OFFを表すマスキング信号に基づいて該検波器の出力からOFF時間のみ湯面レベルを測定・出力させるRMS部、からなる二次信号処理機構とを具備することを特徴とする連続鋳造における溶融金属湯面レベル計。
(3)一次コイルと二次コイルで構成される渦流式レベルセンサーと、前記一次コイルに一次信号を送るための一次信号発生装置と、前記二次コイルからの二次信号を、前記制御部からのマスキング信号にしたがって信号処理して、湯面レベルを測定する前記二次信号処理機構とからなることを特徴とする(2)に記載の連続鋳造における溶融金属湯面レベル計。
【0011】
(4)前記鋳型内の溶融金属に電磁力を付与するための、鋳型を取り囲むように配置した電磁コイルと、前記電磁コイルの電流を一定周期で通電し、その通電中にOFF時間を任意の回数設けて、次いで一定周期で通電する操作を繰り返し行う制御部と、(2)又は(3)に記載の溶融金属湯面レベル計とを具備する溶融金属の連続鋳造装置であって、前記制御部は、前記繰り返しの周期を、前記一定周期の通電の周波数(f)、通電ON/OFFピッチ(To)との関係を、
60≦f≦400(Hz)、および、30≦To≦300(msec)、
の条件で通電することを特徴とする溶融金属の連続鋳造装置。
(5)(4)に記載の溶融金属の連続鋳造装置において、
前記制御部は前記OFF時に前記電磁コイルへの電流を完全に停止する代わりに、前記渦流式レベル計または鋳型内蔵式レベル計との電磁界の相互作用がないレベルまでの小さな値の電流を通電することを特徴とする溶融金属の連続鋳造装置。
【0012】
(6)鋳型を取り囲むように配置した電磁コイルを用いて前記鋳型内の溶融金属に電磁力を付与する溶融金属の連続鋳造方法において、制御部を用いて、前記電磁コイルの電流を一定周期で通電し、その通電中にOFF時間を任意の回数設けて、次いで一定周期で通電する操作を繰り返し行い、(2)又は(3)に記載の溶融金属湯面レベル計を用いて、前記OFF時間のみ湯面レベルを測定して湯面レベル制御することを特徴とする溶融金属の連続鋳造方法。
【0013】
【発明の実施の形態】
以下に本発明の実施態様を概要図に基づいて説明する。
図1は、本発明による連続鋳造における溶融金属湯面レベル計の概要図を示したものである。図1において、鋳型1内の溶融金属2の湯面3に相当する位置に鋳型1の外部周囲に電磁気発生装置4を設け、これから発生される交流電流により前記溶融金属を対流・攪拌させている。溶融金属2の湯面3の直上には湯面レベルを測定するための湯面レベルセンサー5(通常は、渦流式レベル計または鋳型内蔵式レベル計が用いられている。)が設置される。この湯面レベルセンサー5は、内部に導電性強磁性物質6を挟んで湯面と平行に上下に一次コイル7および二次コイル8が配置されている。この状態で溶融金属の湯面レベルを測定使用とすると、電磁気発生装置4と湯面レベルセンサー5を併用すると、電磁コイルを使用する限り電磁気発生装置4内の電磁コイルから発生する交流磁場が、湯面レベルセンサー5に対してノイズとして作用し、正確な湯面レベル検知が行えず、しかも測定精度が悪化していくという障害が常に付きまとうことになる。
【0014】
そこで、本発明者らは、前記ノイズを除去し常に安定した湯面レベルを測定するために、図2に示したように、電源発生電流は電磁気発生装置4内の電磁コイルを介して(A)のように周期的にON/OFFの波形を有しており、ON状態においては電磁コイルから発生する交流磁場が生じ、OFF状態では交流磁場が生じないことに着目し、前記電磁気発生装置4をON/OFFパターンで操業することとした。一方、この電磁気発生装置4のON/OFFパターンで操業に合わせて、(B)に示すように、平行的にON/OFFさせること、つまり、電磁気発生装置4のONパターン時にはマスキングし、OFFパターン時のみ湯面レベルセンサー5から発せられる信号の処理を行うことで湯面レベル測定を行った。すなわち、電磁気発生装置4内の電磁コイルの電流を一定周期で通電し、その通電中に、好ましくは、電磁コイルの電流のON時に回転磁界の向きを正転/逆転させ、OFF時間を任意の回数設けて、次いで一定周期で通電する操作を繰り返し行い、OFF時間のみを渦流式レベル計または鋳型内蔵式レベル計で湯面レベルを測定・出力させることにより湯面レベルを測定することで安定して常に精度の高い溶融金属湯面レベルを測定することが可能になった。その具体的処理を図1に基づいて更に説明する。
【0015】
湯面レベルセンサー5内の一次コイル側には一次信号発生装置9から一次信号が送られる。この一次信号は断続的であっても、常時信号を発していても差し支えない。前記一次信号は導電性強磁性物質6により増幅されて二次コイル8側に伝達され、そして二次信号が発せられる。この二次信号は二次信号処理機構10に送られ二次信号処理がなされる。この二次信号処理機構10は、増幅器フィルター11で増幅され、波高値検波或いは位相検波を行うための検波器12、RMS13、増幅器14で構成されている。この二次信号処理機構10内には、二次信号処理と共に、電源制御部からのマスキング信号に従って信号処理を行ったり、行わなかったりする。一方、電磁コイルに送給される周波数および電流の通電量の指令を行う制御部15においては、通常の正弦波に加え台形波等の波形を基にして電源のON領域或いはOFF領域の指令を発する。本発明においては、前記制御部15で、前記電磁コイルの電流を1〜5周期で通電し、その通電中にOFF時間を任意の回数設けて、次いで1〜5周期で通電する操作を繰り返し行うことが好ましいが、通電がOFFの時のみ起動するよう構成されている。また、前記電磁コイルの電流の通電OFF時は、電磁コイルと渦流式レベル計または鋳型内蔵式レベル計との電磁界の相互作用がないレベルまで小さい値の電流を通電する状態として操業することにより、更にノイズの少ない状態で湯面レベルを測定することが可能になる。更に、前記制御部15からの指令は、一次信号発生装置9およびRMS13に送られ、通電OFF時に前記溶融金属の湯面レベルを測定する情報処理を行う。
【0016】
特に、本発明では、前記繰り返しの周期を、周波数(f)、通電ON/OFFピッチとの関係を、60≦f≦400(Hz)、および、30≦To≦300(msec)の条件で通電することが好ましい。これは、図3(a)に示すように、本発明で周波数と電流との関係から200Hz近傍でノイズが最小値を示し、使用可能な周波数は60〜400Hzの範囲とされる。また、200Hzの周波数で鋳片表面粗度(Rmax)と通電ON/OFFピッチ(To)との関係をみると、図3(b)に示すように通電ON/OFFピッチ(To)が200msecの時に鋳片表面粗度が著しく改善されていることが分かる。従って、鋳片粗度の観点から通電ON/OFFピッチ(To)の範囲を30〜300msecの範囲で通電することが好ましい。なお、前記Toが30msec以下、また300msec以上では湯面レベル計では追随できないことから上記範囲に設定することが好ましい。
【0017】
更に、本発明においては、図4に示すように、渦流式レベル計または鋳型内蔵式レベル計の二次側コイル側に更に変動コイルとマスキング装置を付加することにより、更に電磁コイルから発生する交流磁場ノイズの影響を受けることなく、安定して精度高い溶融金属の湯面レベル検知が可能になる。
【0018】
【発明の効果】
以上説明したように、本発明は電磁コイルに通電中に、電磁コイルの電流をON/OFF、好ましくは、ON時に正転/逆転の操作を導入することにより、或る間隔でOFF時間を任意の回数設け、その際に渦流式レベル計または鋳型内蔵式レベル計で電磁コイルから発生する交流磁場ノイズの影響を受けることなく、安定して精度高い溶融金属の湯面レベル検知が可能になる。
【図面の簡単な説明】
【図1】本発明による連続鋳造における溶融金属湯面レベル計の概要図。
【図2】電磁気発生装置の電磁コイルの電流波形(A)とマスキング(B)波形を示す図。
【図3】(a)は周波数と電流との関係を示す図、(b)は通電ON/OFFピッチ(To)と鋳片表面粗度との関係を示す図。
【符号の説明】
1…鋳型
2…溶融金属
3…湯面
4…電磁コイル
5…渦流式レベル計または鋳型内蔵式レベル計
6…導電性強磁性物質
7…一次コイル
8…二次コイル
9…一次信号発生装置
10…二次信号処理機構
11…増幅器・フィルター
12…検波装置
13…RMS
14…増幅器
15…周波数、電流制御部
16…変動コイル
17…マスキング装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring a molten metal surface level position in a mold during continuous casting of molten metal in continuous casting of molten metal, and a level meter used therefor.
[0002]
[Prior art]
Generally, in continuous casting of molten metal, powder is supplied to the upper surface of the molten metal pool in the mold, and the powder melted by the heat from the molten metal is caused by the relative movement of the mold wall that vibrates up and down and the solidified shell drawn at a constant speed. However, the meniscus and the tip of the solidified shell are deformed by the dynamic pressure generated at the time of the inflow, and this deformation is repeated at the mold oscillation cycle. Periodic wrinkles called are formed. However, if the depth of this flaw is deep, it will lead to slab surface flaw defects, and depending on the steel type, only certain elements will segregate in this oscillation mark valley, and trapping of bubbles and inclusions will increase. This is a cause of yield loss.
[0003]
On the other hand, in continuous casting of a billet or a slab having a small cross-sectional area, a rep seed oil is used instead of the powder. Although this rep seed oil burns at the meniscus and becomes graphite to prevent the solidified shell from seizing on the mold wall, it is difficult to obtain a clear oscillation mark regularly generated on the surface of the cast slab. Thus, the casting operation and the quality stability of the slab are inferior to casting using the powder.
[0004]
As described above, as a method for controlling the initial solidification, as described in JP-A-52-32824, molten metal is poured into a water-cooled mold that vibrates with a lubricant at a constant cycle and continuously downward. In the continuous casting method, an alternating current is continuously applied to the electromagnetic coil provided around the mold, and the electromagnetic force is applied to the meniscus of the molten metal in the mold by using the electromagnetic force generated by the alternating magnetic field. A method for improving the surface properties of a slab by bending is disclosed. Japanese Patent Application Laid-Open No. 64-83348 discloses a powder casting method in which an electromagnetic force is intermittently applied by applying an alternating magnetic field in a pulsed manner when an electromagnetic force is applied to a molten metal in a mold by an electromagnetic coil. A method for further improving the surface properties of the slab is disclosed. Also, in Republished Hei 8-805926, in order to apply electromagnetic force, the amplitude of the alternating current is given the same frequency as the mold vibration, and the mold vibration frequency (fm) and the alternating magnetic field frequency (fp) Is set to 0.69 ≦ ln (fp / fm) ≦ 9.9, where ln is a constant, thereby generating a stable meniscus and continuously obtaining the surface texture effect of the slab. A casting method is disclosed.
[0005]
As for the method for detecting the level of molten metal, a method using a floater, an optical (photoelectric conversion) method, a method using ultrasonic waves and radiation, an immersion electrode method, a thermocouple method, an electromagnetic induction method, etc. Various methods have been developed and implemented. Furthermore, eddy currents generated in molten metal as disclosed in JP-A-3-122526, JP-A-3-138536, JP-A-4-187355 and JP-A-4-238661. A method has been developed to measure the impedance change of the receiving coil due to the size of the signal as a phase change. Japanese Laid-Open Patent Publication No. Hei 4-238661 has also developed a method in which a fluctuation range of the molten metal level is divided and measured by a plurality of detectors, and the discontinuity of the measured value due to the switching of the detectors is suppressed.
[0006]
[Problems to be solved by the invention]
However, when these conventional techniques are actually realized by a continuous casting apparatus in which an electromagnetic induction heating apparatus is installed, there is a problem that the molten metal level of the molten metal in the mold cannot be accurately detected. As the accuracy of the molten metal level detection deteriorates, it becomes difficult to control the molten metal surface level, and it becomes difficult to stably form a meniscus of molten metal, and as a result, it becomes impossible to secure a good surface property of the slab. there were.
[0007]
On the other hand, as a hot water level detecting means used in a continuous casting apparatus, an eddy current hot water level meter applying the electromagnetic induction phenomenon due to an alternating magnetic field as described above is often used. As other means, there are a method using a thermocouple embedded in a mold and a transmission type sensor using γ-rays. However, the eddy current sensor is almost the most excellent in terms of measurement accuracy and responsiveness. Used in continuous casting equipment. However, as long as the electromagnetic coil is used, the AC magnetic field generated from the electromagnetic coil acts as noise on the eddy current level sensor, so that accurate level detection cannot be performed and the measurement accuracy deteriorates. Cause a big problem. For example, when it is used in a magnetic field in continuous electromagnetic induction casting at a frequency of 200 Hz with an intensity of 1,000 (Gauss) or more, the signal output voltage is saturated and measurement becomes impossible, or the magnetic field is turned on even in a magnetic field in pulse electromagnetic induction casting. In this case, there is a serious problem that it is saturated and the molten metal surface cannot be measured.
[0008]
[Means for Solving the Problems]
Therefore, the present inventors are stronger in the pulse application period (ON period) than the eddy current level sensor in a continuous casting apparatus that improves the surface properties of the slab by generating a pulsed magnetic field. Focusing on the fact that noise acts but almost no noise is generated during the pulse application interruption period (OFF period), the pulse ON period and the pulse OFF period are repeated periodically, and the eddy current level meter or the mold built-in level The effect of the AC magnetic field noise generated from the electromagnetic coil is input to the signal processing device of the meter, and the hot water level is detected only in the pulse OFF period and not in the pulse ON period. The molten metal surface level detection of the molten metal can be performed stably and accurately, and the gist thereof is as follows.
[0009]
(1) An electromagnetic coil arranged so as to surround a mold is energized (ON) by a control unit with a current of the electromagnetic coil at a constant cycle, and an OFF time is provided any number of times during the energization, and then energized at a constant cycle. The method of measuring the molten metal level for detecting the molten metal level of the molten metal in the mold, which is used in a continuous casting apparatus that casts the molten metal while applying electromagnetic force to the molten metal in the mold by repeating the operation And, based on the masking signal indicating ON / OFF of energization of the control unit, the molten metal level is measured by measuring and outputting the eddy current level meter or the mold built-in type molten metal level meter only during the OFF time. A method for measuring a molten metal surface level in continuous casting.
[0010]
(2) An operation in which an electromagnetic coil arranged so as to surround the mold is energized at a constant cycle by the control unit, an OFF time is provided any number of times during the energization, and then the operation is performed at a constant cycle. Repeatedly, used in a continuous casting apparatus that casts the molten metal while applying electromagnetic force to the molten metal in the mold, a molten metal level meter for detecting the molten metal level of the molten metal in the mold, a molten metal surface level sensor of eddy current type or template self-contained detector for detecting the output of該湯surface level sensor, and the output of the detection wave device based on the masking signal representing the oN / OFF of energization from the control unit A molten metal surface level meter in continuous casting, comprising a secondary signal processing mechanism comprising an RMS section that measures and outputs the surface level only during OFF time.
(3) An eddy current level sensor composed of a primary coil and a secondary coil, a primary signal generator for sending a primary signal to the primary coil, and a secondary signal from the secondary coil from the controller The molten metal surface level meter in continuous casting according to (2), comprising the secondary signal processing mechanism that performs signal processing according to the masking signal and measures the surface level.
[0011]
(4) An electromagnetic coil arranged so as to surround the mold for applying electromagnetic force to the molten metal in the mold, and a current of the electromagnetic coil are energized at a constant period, and an OFF time is arbitrarily set during the energization. A molten metal continuous casting apparatus, comprising: a control unit that repeatedly performs an operation of energizing at a fixed period; and a molten metal level meter according to (2) or (3), wherein the control parts are the period of the repetition, the certain period of energization of the frequency (f), the relationship between current ON / OFF pitch (the to),
60 ≦ f ≦ 400 (Hz) and 30 ≦ To ≦ 300 (msec),
An apparatus for continuously casting molten metal , characterized by energizing under the following conditions.
(5) In the molten metal continuous casting apparatus according to (4),
Instead of completely stopping the current to the electromagnetic coil at the time of the OFF, the control unit supplies a small current up to a level where there is no electromagnetic field interaction with the eddy current level meter or the mold built-in type level meter. A continuous casting apparatus for molten metal .
[0012]
(6) In a molten metal continuous casting method in which an electromagnetic force is applied to the molten metal in the mold using an electromagnetic coil arranged so as to surround the mold, a current is supplied to the electromagnetic coil at a constant period using a control unit. Energize, set OFF times during energization any number of times, and then repeat the operation of energizing at a constant cycle, and using the molten metal level meter described in (2) or (3), the OFF time A molten metal continuous casting method characterized in that only a molten metal level is measured and the molten metal level is controlled.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to schematic diagrams.
FIG. 1 shows a schematic diagram of a molten metal level meter in continuous casting according to the present invention. In FIG. 1, an
[0014]
Therefore, in order to remove the noise and always measure a stable molten metal surface level, the present inventors, as shown in FIG. 2, generate a power source current via an electromagnetic coil in the electromagnetic generator 4 (A Note that the AC magnetic field generated from the electromagnetic coil is generated in the ON state and the AC magnetic field is not generated in the OFF state. Was operated in an ON / OFF pattern. On the other hand, according to the operation of the ON / OFF pattern of the
[0015]
A primary signal is sent from the primary signal generator 9 to the primary coil side in the hot water level sensor 5. This primary signal may be intermittent or it may be constantly signaled. The primary signal is amplified by the conductive
[0016]
In particular, in the present invention, the repetition period is energized under the conditions of frequency (f), energization ON / OFF pitch, and 60 ≦ f ≦ 400 (Hz) and 30 ≦ To ≦ 300 (msec). It is preferable to do. As shown in FIG. 3 (a), the noise shows a minimum value in the vicinity of 200 Hz from the relationship between the frequency and the current in the present invention, and the usable frequency is in the range of 60 to 400 Hz. Further, when the relationship between the slab surface roughness (Rmax) and the energization ON / OFF pitch (To) is observed at a frequency of 200 Hz, the energization ON / OFF pitch (To) is 200 msec as shown in FIG. It can be seen that sometimes the slab surface roughness is significantly improved. Therefore, it is preferable to energize the energization ON / OFF pitch (To) in the range of 30 to 300 msec from the viewpoint of slab roughness. In addition, when the To is 30 msec or less, and 300 msec or more, the molten metal level meter cannot follow, it is preferable to set the above range.
[0017]
Furthermore, in the present invention, as shown in FIG. 4, by adding a variable coil and a masking device to the secondary coil side of the eddy current type level meter or the mold built-in type level meter, the alternating current generated from the electromagnetic coil is further increased. It is possible to detect the molten metal surface level stably and accurately without being affected by magnetic field noise.
[0018]
【The invention's effect】
As described above, according to the present invention, when the electromagnetic coil is energized, the current of the electromagnetic coil is turned ON / OFF, and preferably the OFF time can be arbitrarily set at a certain interval by introducing the forward / reverse operation when ON. In this case, the molten metal level level of the molten metal can be detected stably and accurately without being affected by the AC magnetic field noise generated from the electromagnetic coil by the eddy current level meter or the built-in type level meter.
[Brief description of the drawings]
FIG. 1 is a schematic view of a molten metal level meter in continuous casting according to the present invention.
FIG. 2 is a diagram showing a current waveform (A) and a masking (B) waveform of an electromagnetic coil of an electromagnetic generator.
3A is a diagram showing the relationship between frequency and current, and FIG. 3B is a diagram showing the relationship between energization ON / OFF pitch (To) and slab surface roughness.
[Explanation of symbols]
DESCRIPTION OF
14 ...
Claims (6)
前記制御部の通電のON/OFFを表すマスキング信号に基づいて、OFF時間のみ渦流式レベル計又は鋳型内蔵式湯面レベル計を測定・出力させることにより湯面レベルを測定することを特徴とする連続鋳造における溶融金属湯面レベル測定方法。The electromagnetic coil arranged so as to surround the mold is energized (ON) by a control unit with a current of the electromagnetic coil at a constant period, and an OFF time is provided any number of times during the energization, and then the operation of energizing at a constant period is performed. A method of measuring a molten metal level for detecting a molten metal level of the molten metal in the mold, which is used in a continuous casting apparatus that repeatedly casts the molten metal while applying electromagnetic force to the molten metal in the mold. ,
Based on a masking signal indicating ON / OFF of energization of the control unit, the molten metal level is measured by measuring and outputting the eddy current level meter or the mold built-in type molten metal level meter only during the OFF time. Method for measuring the molten metal surface level in continuous casting.
渦流式又は鋳型内蔵式の湯面レベルセンサーと、
該湯面レベルセンサーの出力を検波する検波器、及び前記制御部からの通電のON/OFFを表すマスキング信号に基づいて該検波器の出力からOFF時間のみ湯面レベルを測定・出力させるRMS部、からなる二次信号処理機構とを具備することを特徴とする連続鋳造における溶融金属湯面レベル計。The electromagnetic coil arranged so as to surround the mold is energized with a current of the electromagnetic coil at a constant period by the control unit, and an OFF time is provided any number of times during the energization, and then the operation of energizing at a constant period is repeated, A molten metal level meter for detecting a molten metal level of the molten metal in the mold, which is used in a continuous casting apparatus for casting the molten metal while applying electromagnetic force to the molten metal in the mold,
Eddy current type or mold built-in level sensor,
A detector for detecting the output of the molten metal level sensor, and an RMS unit for measuring and outputting the molten metal level only during the OFF time from the output of the detector based on a masking signal indicating ON / OFF of energization from the control unit. A molten metal surface level meter in continuous casting, comprising a secondary signal processing mechanism comprising:
前記一次コイルに一次信号を送るための一次信号発生装置と、
前記二次コイルからの二次信号を、前記制御部からのマスキング信号にしたがって信号処理して、湯面レベルを測定する前記二次信号処理機構とからなることを特徴とする請求項2に記載の連続鋳造における溶融金属湯面レベル計。An eddy current level sensor composed of a primary coil and a secondary coil;
A primary signal generator for sending a primary signal to the primary coil;
Wherein the secondary signal from the secondary coil, and signal processing in accordance with the masking signal from the control unit, to claim 2, characterized in that it consists of a secondary signal processing mechanism for measuring the bath level level Molten metal level meter in continuous casting of steel.
前記電磁コイルの電流を一定周期で通電し、その通電中にOFF時間を任意の回数設けて、次いで一定周期で通電する操作を繰り返し行う制御部と、
請求項2又は請求項3に記載の溶融金属湯面レベル計とを具備する溶融金属の連続鋳造装置であって、
前記制御部は、前記繰り返しの周期を、前記一定周期の通電の周波数(f)、通電ON/OFFピッチ(To)との関係を、
60≦f≦400(Hz)、および、
30≦To≦300(msec)、
の条件で通電することを特徴とする溶融金属の連続鋳造装置。An electromagnetic coil arranged to surround the mold for applying electromagnetic force to the molten metal in the mold;
A controller that energizes the current of the electromagnetic coil at a constant cycle, sets an arbitrary number of OFF times during the energization, and then repeatedly performs an operation of energizing at a constant cycle;
A molten metal continuous casting apparatus comprising the molten metal level meter according to claim 2 or 3,
The control unit determines the relationship between the repetition cycle, the energization frequency (f) of the constant cycle, and the energization ON / OFF pitch (To).
60 ≦ f ≦ 400 (Hz), and
30 ≦ To ≦ 300 (msec),
An apparatus for continuously casting molten metal, characterized by energizing under the following conditions.
前記制御部は前記OFF時に前記電磁コイルへの電流を完全に停止する代わりに、前記渦流式レベル計または鋳型内蔵式レベル計との電磁界の相互作用がないレベルまでの小さな値の電流を通電することを特徴とする溶融金属の連続鋳造装置。In the continuous casting apparatus of the molten metal according to claim 4,
Instead of completely stopping the current to the electromagnetic coil at the time of the OFF, the control unit supplies a small current up to a level where there is no electromagnetic field interaction with the eddy current level meter or the mold built-in type level meter. A continuous casting apparatus for molten metal.
制御部を用いて、前記電磁コイルの電流を一定周期で通電し、その通電中にOFF時間を任意の回数設けて、次いで一定周期で通電する操作を繰り返し行い、
請求項2又は請求項3に記載の溶融金属湯面レベル計を用いて、前記OFF時間のみ湯面レベルを測定して湯面レベル制御することを特徴とする溶融金属の連続鋳造方法。In a continuous casting method of molten metal that applies electromagnetic force to the molten metal in the mold using an electromagnetic coil arranged so as to surround the mold,
Using the control unit, the current of the electromagnetic coil is energized at a constant cycle, the OFF time is set to any number during the energization, and then the operation of energizing at a constant cycle is repeated
A molten metal level meter according to claim 2 or 3, wherein the molten metal level is measured only during the OFF time to control the molten metal level.
Priority Applications (8)
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JP36031597A JP3878309B2 (en) | 1997-12-26 | 1997-12-26 | Molten metal level measurement method and molten metal level meter in continuous casting of molten metal |
PCT/JP1998/005551 WO1999029453A1 (en) | 1997-12-08 | 1998-12-08 | Continuous casting apparatus using a molten metal level gauge |
CA002280523A CA2280523C (en) | 1997-12-08 | 1998-12-08 | Continuous casting apparatus using a molten metal level gauge |
EP98957227A EP0979696B1 (en) | 1997-12-08 | 1998-12-08 | Continuous casting apparatus using a molten metal level gauge |
KR1019997007135A KR100341614B1 (en) | 1997-12-08 | 1998-12-08 | Continous casting apparatus using a molten metal level guage |
US09/367,179 US6337566B1 (en) | 1997-12-08 | 1998-12-08 | Continuous casting apparatus using a molten metal level gauge |
DE69841495T DE69841495D1 (en) | 1997-12-08 | 1998-12-08 | |
CNB988023652A CN1168560C (en) | 1997-12-08 | 1998-12-08 | Continous casting apparatus using molten metal level gauge |
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JP36031597A JP3878309B2 (en) | 1997-12-26 | 1997-12-26 | Molten metal level measurement method and molten metal level meter in continuous casting of molten metal |
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