JP3577389B2

JP3577389B2 - Flow controller for molten metal

Info

Publication number: JP3577389B2
Application number: JP16908796A
Authority: JP
Inventors: 崎敬介藤
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1996-06-28
Filing date: 1996-06-28
Publication date: 2004-10-13
Anticipated expiration: 2016-06-28
Also published as: JPH105949A

Description

【０００１】
【発明の属する技術分野】
本発明は、鋳型内の溶融金属を水平循環駆動する流動制御装置に関する。
【０００２】
【従来の技術】
例えば連続鋳造では、タンデイッシュより鋳型に溶鋼が注入され、鋳型において溶鋼は鋳型壁面から次第に冷却されつつ引き抜かれる。同一高さの鋳型壁面における温度が不均一であると、表面割れやシェル破断を生じ易い。これを改善するために、従来は、電磁石あるいはリニアモ−タを用いて、鋳型内で溶鋼をその上面と平行に、鋳型壁面に沿って流動駆動する（例えば特開平１−２２８６４５号公報）。また溶鋼表層部での溶鋼流動速度が不均一であると、溶鋼上のパウダ−が溶鋼中に巻き込まれ、これが鋼片中の欠陥となる。鋳型にはタンデイッシュより注湯ノズルを介して溶鋼が供給されるが、この溶鋼が鋳型に流入する速度が高く、これによりパウダ−巻込みを生じ易い。これを改善するために溶鋼に静磁界を加える電磁ブレ−キ装置が提示されている（例えば特開平３−２５８４４２号公報）。
【０００３】
特開平１−２２８６４５号公報に提示の溶鋼の流動駆動はある程度の効果があるものの、注湯ノズルを介して鋳型に流入する溶鋼の流れにより鋳型壁面に沿った水平循環流動が乱される。この種の流動駆動には、鋳型の長辺に沿って配列された複数個の磁極のそれぞれに電気コイルを巻回したリニアモ−タ型の電磁石が用いられ、電気コイルは３相の各相毎に束ねられ、１２０°位相のずれた３相電源の各相に、束ねられた単位で接続され、３相電源の電圧および又は周波数をインバ−タやサイクロコンバ−タで調整し、これにより所要の駆動力および速度が得られる。
【０００４】
図１２の（ａ）に鋳型の垂直断面図を示し、図１２の（ｂ）には、（ａ）のＣＣ−ＣＣ線で鋳型内溶鋼を見た平面を示し、図１２の（ｃ）には、鋳型の上面より鋳型内溶鋼の上面（メニスカス）を見おろした平面を示す。図１２の（ａ）に実線矢印で示すように、溶鋼１は、ノズル２から流出口３を通して鋳型内に流れ込み、鋳型短辺方向に噴出流(1)，(5)を生む。図１２の（ｂ）は流出口３から噴出する溶鋼流を、流出口３を含む断面で示したものである。流出口３から噴出する噴出流(1)，(5)は、鋳型短辺６Ｌに当って上方に向う上昇流(2) と下方に向う下降流(3)となり、また鋳型短辺７Ｒに当って上方に向う上昇流(6)と下方に向う下降流(7)となる。上方に流れる上昇流(2)，(6)が、メニスカスでは図１２の（ｃ）に実線矢印で示すように、ノズル２に向かう表層流(4)，(8)を生ずる。この表層流(4)，(8)は溶鋼１中にメニスカス上のパウダＰＷを巻き込み易い。一方、溶鋼１が固体に変わるときにＣＯなどの気体（気泡）が発生する。加えて、鋳型ＭＤ内面の一部に溶鋼１が滞留するとパウダＰＷが溶鋼１に残留し易く、しかもブレ−クアウトの原因となる焼付きとなり易い。これらを防止するため、表層に安定した整流を形成させるのが良い。
【０００５】
そこで従来は、図１３に示すように、鋳型長辺に沿って鋳型の外側面に対向するリニアモ−タＬＭ１〜ＬＭ４を設置し、図に点線矢印で示す方向の電磁駆動力（推力）を表層の溶鋼に与えて、図に２点鎖線矢印で示すような、鋳型内壁に沿う循環流を溶鋼の表層に生起しようとしている。
【０００６】
図１３に示すリニアモ−タＬＭ３が発生する電磁駆動力は、図に点線矢印で示す様に右から左に向う方向であるので、表層流(8)と同じ向きとなり、溶鋼を加速するが、リニアモ−タＬＭ４が発生する電磁駆動力は、表層流(4)と対向する方向となり、溶鋼は減速される。
【０００７】
リニアモ−タＬＭ２が発生する電磁駆動力は、図１３に点線矢印で示す様に左から右に向う方向であるので表層流(4)と同じ向きとなり、溶鋼を加速するが、リニアモ−タＬＭ１が発生する電磁駆動力は、表層流(8)と対向する方向となり、溶鋼は減速される。
【０００８】
−方、特開平３−２５８４４２号公報にて提案されている「電磁ブレ−キ装置」では、鋳型長辺に沿って長辺の幅とほぼ等しい幅の一対の電磁石が、メニスカス下方で鋳型を挾んで対向して設置され、その電気コイルは直流電流により励磁される。その電磁石の発生する一定磁界（静磁界）中に流れる溶鋼にはフレミングの右手の法則に従がう起電力が生じ、磁束を周回する電流が流れ、この電流と磁界との相互作用により溶鋼に、その流れを止めようとする制動力が働き、これが図１２の（ａ）に示す下方への溶鋼流(3)，(7)を制動し、溶鋼流(3)，(7)に伴なう介在物の下方への潜りこみを抑制する。
【０００９】
【発明が解決しようとする課題】
リニアモ−タＬＭ１〜ＬＭ４で生起しようとしている溶鋼の表層の鋳型内壁に沿う循環流（図１３に２点鎖線矢印で示す方向）は、表層流(4)，(8)の影響を受ける。すなわち強い表層流（反転流）(4)，(8)は、リニアモ−タＬＭ１〜ＬＭ４による表層の鋳型内壁に沿う循環流を阻害する。そこで該循環流を形成するためには強い表層流（反転流）(4)，(8)を打消す様な強い電磁推進力を必要とし、リニアモ−タＬＭ１〜ＬＭ４には強度の励磁電流を供給せざるを得ない。
【００１０】
上記の強い表層流（反転流）(4)，(8)は、図１２の（ａ）に示すノズル２の注湯ノズルの流出口３から鋳型内空間に流出する噴出流(1)，(5)が、強く鋳型短辺６Ｌ，７Ｒに衝突し、大きな上昇流(2)，(6)を生ずるために発生する。
【００１１】
また、電磁ブレ−キ装置を単独で使用した場合には、注湯ノズル２から鋳型内に流れ込む溶鋼流に対する速度均一化の効果は認められるとしても、リニアモ−タ等を使用した鋳型内溶鋼駆動装置と併用した場合には、該駆動装置による溶鋼流（循環流）をも制動してしまう。すなわち該電磁ブレ−キは、印加する一定磁界中を移動する溶鋼に対し制動力を加えるものであるので、下方向に流れる溶鋼流(3)，(7)のみならず、印加する一定磁界を横切って移動する鋳型内壁に沿う溶鋼循環流に対しても制動力が働いてしまうことになる。
【００１２】
本発明の流動制御装置は、鋳型内に発生する上昇流及び下降流の減少を計ることを第１の目的とし、メニスカス付近における鋳型の内表面に沿った溶鋼の流れ駆動を効果的にすることを第２の目的とし、下降溶鋼流制御のための電磁ブレ−キによる制動の必要性を低減又は該制動を不要にすることを第３の目的とする。
【００１３】
【課題を解決するための手段】
本発明の溶融金属の流動制御装置は、
（１）電磁力の発生装置である電磁石(8〜11)が、鋳型(MD)に溶融金属(1)を注入するノズル(2)の流出口と実質上同一レベルに、鋳型(MD)の対向２長辺(5A,6L)に沿って配置され、該レベルで２長辺に沿って水平循環駆動される溶融金属(1)の各長辺に沿う流動の起点側鋳型短辺から長辺に沿って１／４長辺幅点における鋳型長辺方向に沿う水平方向の溶融金属水平速度である起点側速度Ｖｓが、各長辺に沿う流動の終点側鋳型短辺から鋳型長辺に沿って１／４長辺幅点における鋳型長辺方向に沿う水平方向の溶融金属水平速度である終点側速度Ｖｅに対して、Ｖｓ≧Ｖｅとなる電磁力を溶融金属(1)に与えることを特徴とする。
【００１４】
これによれば、前記電磁石(8〜11)を鋳型(MD)に溶融金属(1)を注入するノズル(2)の流出口と、実質上同一レベルに配置するので、ノズル(2)から噴出する溶融金属噴出流((1),(5))に対して電磁力が加わる。鋳型長辺に沿った溶融金属水平流の起点側鋳型短辺から１／４長辺幅点における溶融金属水平方向速度を起点側速度(Vs)とし、鋳型長辺に沿った溶融金属水平流の終点側鋳型短辺から１／４長辺幅点における溶融金属水平方向速度を終点側速度(Ve)とした時、Ｖｓ≧Ｖｅとなる様に、電磁石(8〜11)から溶融金属に推力あるいは制動力を与える。
【００１５】
なお、理解を容易にするためにカッコ内には、図面に示し後述する実施例の対応要素の記号を、参考までに付記した。
【００１６】
【発明の実施の形態】
本発明の好ましい実施例では、
（２）また本発明の概要をより具体的に説明すると、
鋳型(MD)の第１長辺(4F)に沿って配置された第１電磁石(8)及び第２電磁石(9)、並びに第２長辺(5A)に沿って配置された第３電磁石(10)及び第４電磁石(11)；前記第２電磁石(9)及び第３電磁石(10)に第１長辺(4F)および第２長辺(5A)に沿う水平方向の移動磁界を生じさせる第１励磁手段(INV1)、並びに前記第１電磁石(8)及び第４電磁石(11)に第１長辺(4F)および第２長辺(5A)に沿う水平方向の移動磁界を生じさせる第２励磁手段(INV2)；を備える溶融金属の流動制御装置において、
第１〜第４電磁石(8〜11)は、鋳型(MD)に溶融金属(1)を注入するノズル(2)の流出口(3)と実質上同一レベルに配置され、
第１電磁石(8)及び第２電磁石(9)が、該レベルで水平循環駆動される溶融金属(1)の第１長辺に沿う水平流の起点側鋳型短辺(6L)から第１長辺(4F)に沿って１／４長辺幅点における溶融金属水平方向速度である起点側速度Ｖｓが、第１長辺に沿う水平流の終点側鋳型短辺(7R)から第１長辺に沿って１／４長辺幅点における溶融金属水平方向速度である終点側速度Ｖｅに対して、Ｖｓ≧Ｖｅとなる推力を溶融金属に与え、かつ、
第３電磁石(10)及び第４電磁石(11)が、該レベルで水平循環駆動される溶融金属(1)の第２長辺に沿う水平流の起点側鋳型短辺(7R)から第２長辺(5A)に沿って１／４長辺幅点における溶融金属水平方向速度である起点側速度Ｖｓが、第２長辺に沿う水平流の終点側鋳型短辺(6L)から第２長辺に沿って１／４長辺幅点における溶融金属水平方向速度である終点側速度Ｖｅに対して、Ｖｓ≧Ｖｅとなる推力を溶融金属に与える、
ことを特徴とする。
【００１７】
これによれば、流出口(3)から鋳型(MD)に注入された溶融金属(1)を流動駆動するために、流出口(3)と実質上同一レベルに、鋳型(MD)の第１長辺(4F)に沿って第１電磁石(8)及び第２電磁石(9)が配置される。同様に第２長辺(5A)に沿って第３電磁石(10)及び第４電磁石(11)が配置される。第２電磁石(9)及び第３電磁石(10)は第１励磁手段(INV1)で励磁し、第１電磁石(8)及び第４電磁石(11)は第２励磁手段(INV2)で励磁することによって、鋳型(MD)内の溶融金属(1)を流動駆動する。そして流出口(3)から鋳型(MD)に注入する溶融金属(1)と、流出口(3)と実質上同一レベルに対向配置された電磁石(8〜11)の推力の合成により発生する、溶融金属(1)の鋳型長辺に沿った水平流速を、起点側速度Ｖｓ≧終点側速度Ｖｅとなる様に、電磁石(8〜11)から溶融金属に推力あるいは制動力を与える。
【００１８】
前記起点側速度(Vs)は、鋳型長辺の起点側鋳型短辺から１／４長辺幅点における溶融金属水平方向速度であり、前記終点側速度(Ve)は、鋳型長辺の終点側鋳型短辺から１／４長辺幅点における溶融金属水平方向速度である。
【００１９】
Ｖｓ≧Ｖｅとすることにより、溶融金属噴出流((1),(5))が鋳型短辺に衝突する際に発生する溶融金属の上昇流((2),(6))及び下降流((3),(7))を小さくすることが出来る。鋳型短辺に衝突して発生した溶融金属の上昇流((2),(6))は、鋳型内溶融金属メニスカス下方において方向を反転し、ノズル方向に向う表層流(反転流)((4),(8))流れとなるが、Ｖｓ≧Ｖｅとすれば溶融金属の上昇流((2),(6))は小さくなるので該反転流((4),(8))も小さくなる。鋳型長辺に沿って対向配置された電磁石(8〜11)が惹起する溶融金属(1)の流動駆動は、メニスカス下方においても該反転流に影響されることは少なく、従って鋳型(MD)の内表面に沿った循環流が実現する。この様にスム−スな溶鋼の回転撹拌が行なわれるので、溶融金属(1)の突出流による鋳片内部への異物(介在物)の巻き込み(侵入)が抑制され、鋳片の内部品質が向上する。
【００２０】
また下降流((3),(7))も小さくなるので下降流を抑制するための電磁ブレ−キの必要性は低減し、あるいは電磁ブレ−キを不要とする。
【００２１】
（３）また、第１電磁石(8)と第４電磁石(11)の発生する推力は実質上同一で、また第２電磁石(9)と第３電磁石(10)の発生する推力は実質上同一であり、かつ第１長辺と第２長辺に沿う前記各水平流の各終点側に位置する第１電磁石(8)と第４電磁石(11)の発生する推力は、各起点側に位置する第２電磁石(9)と第３電磁石(10)の発生する推力より小である。
【００２２】
これによれば、鋳型(MD)の大略中央に配設されたノズル(2)の流出口(3)から注湯される溶鋼(1)は第１短辺(6L)に向って流出する噴出流((1))と、第２短辺(7R)に向って流出する噴出流((5))を形成する。第１〜第４電磁石(8〜11)は、流動駆動する溶融金属(1)の鋳型長辺(4F,5A)に沿う水平方向速度を、Ｖｓ≧Ｖｅとするために、各々前記噴出流((1),(5))と対向する向きの水平方向推力を発生する。すなわち、噴出流((1)，(5))の流速を低減する。
【００２３】
一方第１電磁石(8)と第４電磁石(11)の発生する推力の大きさは同一で、また第２電磁石(9)と第３電磁石(10)の発生する推力の大きさは同一であり、かつ第１電磁石(8)と第４電磁石(11)の発生する推力の大きさは第２電磁石(9)と第３電磁石(10)の発生する推力の大きさより小さく設定するので、両者の差分が鋳型(MD)の内壁に沿った循環溶鋼流を惹起する。この様に噴出流の流速を低減したことにより、短辺(6L)に衝突する水平流速((1))が減り、上昇流((2))及び下降流((3))が小さくなる。同様に短辺(7R)に衝突する水平流速((5))が減り、上昇流((6))及び下降流((7))が小さくなる。
【００２４】
（４）また、本発明の他の実施形態では、第１長辺と第２長辺に沿う前記各水平流の各起点側に配置した電磁石(9,10)は溶融金属(1)を鋳型長辺(4F,5A)に沿う水平方向に流動駆動するリニアモ−タであり、各終点側に配置した電磁石(8,11)は溶融金属(1)の水平方向移動を制動する電磁ブレ−キである。
【００２５】
これによれば、流動駆動する溶融金属(1)の鋳型長辺(4F,5A)に沿う水平方向速度を、Ｖｓ≧Ｖｅとするために、例えば第１長辺(4F)に沿って配置された第１電磁石(8)と第２電磁石(9)において、起点側に配置した第２電磁石(9)はリニアモ−タとして溶鋼を駆動し、終点側に配置した第１電磁石(8)は電磁ブレ−キとして流動溶鋼を制動する。この結果、短辺(7R)に衝突する水平流速が減り、上昇流((6))及び下降流((7))が小さくなる。同様に第２長辺(5A)に沿って配置された第３電磁石(10)と第４電磁石(11)において、起点側に配置した第３電磁石(10)はリニアモ−タとして溶鋼を駆動し、終点側に配置した第４電磁石(11)は電磁ブレ−キとして流動溶鋼を制動する。この結果、短辺(6L)に衝突する水平流速が減少し、上昇流((2))及び下降流((3))が小さくなる。
【００２６】
（５）また、本発明の他の実施形態では、第１長辺と第２長辺に沿う前記各水平流の各起点側に配置した電磁石(9,10)の励磁電流をＩ１，各終点側に配置した電磁石(8,11)の励磁電流をＩ２とした時に、電流比α＝Ｉ２／Ｉ１を、０≦α≦０．５とする。
【００２７】
これによれば、Ｖｓ≧Ｖｅとするために、例えば第１長辺(4F)に沿って配置された第１電磁石(8)と第２電磁石(9)において、起点側に配置した第２電磁石(9)の励磁電流をＩ１として溶融金属(1)を駆動し、終点側に配置した第１電磁石(8)の励磁電流をＩ２として溶融金属(1)を駆動する。この電流比α＝Ｉ２／Ｉ１を、０≦α≦０．５とする。すなわち起点側に配置した第２電磁石(9)には強い励磁電流を加えて溶融金属(1)に対する推力を強くし、終点側に配置した第１電磁石(8)には弱い励磁電流を加えて溶融金属(1)に対する推力を弱くする。この結果、短辺(7R)に衝突する水平流速が減少し、上昇流((6))及び下降流((7))が小さくなる。
【００２８】
同様に第２長辺(5A)に沿って配置された第３電磁石(10)と第４電磁石(11)において、起点側に配置した第３電磁石(10)の励磁電流をＩ１として溶融金属(1)を駆動し、終点側に配置した第４電磁石(11)の励磁電流をＩ２として溶融金属(1)を駆動する。この電流比α＝Ｉ２／Ｉ１を、０≦α≦０．５とする。すなわち起点側に配置した第２電磁石(9)には強い励磁電流を加えて溶融金属(1)に対する推力を強くし、終点側に配置した第１電磁石(8)には弱い励磁電流を加えて溶融金属(1)に対する推力を弱くする。この結果、短辺(6L)に衝突する水平流速が減り、上昇流((2))及び下降流((3))が小さくなる。
【００２９】
なお、図１３に示す従来使用されていたリニアモ−タＬＭ１〜ＬＭ４と同様な使い方をした場合には、起点側に配置したリニアモ−タＬＭ２，ＬＭ３に流通する電流Ｉ１と、終点側に配置したリニアモ−タＬＭ１，ＬＭ４に流通する電流Ｉ２は等しいので、α＝Ｉ２／Ｉ１＝１である。この場合にはリニアモ−タＬＭ１〜ＬＭ４による推力は同一なので短辺に衝突する水平流速が速くなり、従って上昇流及び下降流が大きくなる。
【００３０】
本発明の方法によれば、ノズル(2)の流出口(3)と実質上同一レベルの面内で溶鋼が循環駆動されて、該レベルから上方へ向かう上昇流ならびに下方へ向かう下降流が抑制され、これにより表層に比較的に定速度で安定した水平循環流が得られる。これにより気泡の浮上が促進され、溶融金属(1)中へのパウダ巻き込みがなくなり、ノズル(2)の流出口(3)と実質上同一レベルの鋳型内面がきれいにぬぐわれて溶融金属の滞留がなくなり、鋳型(MD)に対する鋳片の焼付きが少くなる。
【００３１】
本発明の他の目的および特徴は、図面を参照した以下の実施例の説明より明らかになろう。
【００３２】
【実施例】
−第１実施例−
図１に、本発明の一実施例である４組の電磁石（リニアモ−タ）８〜１１を備えた連続鋳造鋳型ＭＤの縦断面を示す。鋳型ＭＤには、溶鋼１が注入ノズル２の流出口３を通して、上方から下方（垂直方向ｚ）に向けて注入され、また溶鋼１のメニスカス（表面）はパウダＰＷで覆われている。鋳型ＭＤは図示しない水箱ならびに鋳型内水流路に流れる冷却水で冷却され、溶鋼１は鋳型の冷却された表面に接する部分から次第に内部に向けて固まって行き、鋳片となって連続的に引き抜かれる。しかし鋳型ＭＤ内には注入ノズル２を通して溶鋼１が注がれるので、鋳型ＭＤ内には常時溶鋼１が存在する。
【００３３】
鋳型ＭＤの長辺４Ｆの長手方向に沿って、かつ注入ノズル２の流出口３と大略同じ高さにリニアモ−タ８，９が、また鋳型ＭＤの長辺５Ａの長手方向に沿って、リニアモ−タ８，９と対向して２個のリニアモ−タ１０，１１が設けられており、これらがノズル２の流出口３と大略同じ高さの溶鋼１に電磁力を与える。
【００３４】
図２に、図１に示す鋳型ＭＤの平面（上面）を示す。図２において、４Ｆ及び５Ａは連続鋳造鋳型ＭＤの第１及び第２長片、６Ｌおよび７Ｒは第１および第２短片であり、これらが囲む空間に、注入ノズル２を通して溶鋼１が、図２紙面の表面から裏面に向けて（垂直方向ｚで上方から下方に）注入される。各片（４Ｆ，５Ａ，６Ｌ，７Ｒ）は銅板でなる内壁（４ｕ，５ｕ，６ｕ，７ｕ）に非磁性体ステンレス板でなる外壁（４ｓ，５ｓ，６ｓ，７ｓ）を裏当したものである。
【００３５】
この実施例では、鋳型内の溶鋼１を、鋳型長片４Ｆに沿って−ｙから＋ｙの方向に（紙面で下から上方向に）駆動するために、鋳型ＭＤの長辺４Ｆに沿って短辺６Ｌ側に配置した３相リニアモ−タ型電磁石９で比較的大きな推力を加え、また鋳型ＭＤの長辺４Ｆに沿って短辺７Ｒ側に配置した３相リニアモ−タ型電磁石８で比較的小さな推力を加える。同様に鋳型内の溶鋼１を、鋳型長辺５Ａに沿って短辺７Ｒ側に配置した配置した３相リニアモ−タ型電磁石１０で比較的大きな推力を加え、また鋳型ＭＤの長辺５Ａに沿って短辺６Ｌ側に配置した３相リニアモ−タ型電磁石１１で比較的小さな推力を加える。
【００３６】
図１及び図２に示すように、本実施例では、電磁石８のコア８１には６個のスロットがあり、スロットのそれぞれに電気コイル８ａ〜８ｆが挿入されており、「胴巻き」としている。なお、電磁石コア８１および電気コイル８ａ〜８ｆは冷却され、かつ耐熱カバ−で被覆されているが、冷却構造およびカバ−は図示を省略している。電磁石コア８１は鋳型ＭＤと対向する内側にスロットがある櫛形であり、各スロットに電気コイルが挿入され、スロット間の凸部端面が磁極を形成し、その端面がノズル２の流出口３と大略同一高さで溶鋼１と対向している。他の電磁石９，１０及び１１も電磁石８と同様な構造である。
【００３７】
電磁石８〜１１は、図３の（ａ）に示す実線矢印の推力（方向及び大きさ）を溶鋼１に与えようとするものであり、この実施態様では、第１電磁石８と第２電磁石９では異なった推力を発生するように、また第３電磁石１０と第４電磁石１０では異なった推力を発生するように、各電磁石に異なったレベルの電流を通電する。この内容は後述する。
【００３８】
図４に、図２に示す電磁石８の電気コイル８ａ〜８ｆ、電磁石９の電気コイル９ａ〜９ｆ、電磁石１０の電気コイル１０ａ〜１０ｆ、及び電磁石１１の電気コイル１１ａ〜１１ｆの結線および電源回路との接続態様を示す。図４に示す各電磁石８〜１１の結線は２極（Ｎ＝２）のものであり、電気コイルに３相交流を通電する。例えば、電気コイル８ａ〜８ｆは、図４では左から右に、ｕ，ｕ，Ｖ，Ｖ，ｗ，ｗ，Ｕ，Ｕ，ｖ，ｖ，Ｗ，Ｗと表わしているが、Ｕとｕ，Ｖとｖ，Ｗとｗはそれぞれ電磁石コアに設けられたスロットに巻回された１組のコイルの巻始め端と巻終り端を意味する。そして「Ｕ」に３相交流電源のＵ相が接続されている場合には正相通電を、「ｕ」に３相交流電源のＵ相が接続されている場合にはＵ相の逆相通電（Ｕ相より１８０度の位相づれ通電）を表わす。
【００３９】
同様に、「Ｖ」は３相交流のＶ相の正相通電を、「ｖ」はＶ相の逆相通電を、「Ｗ」は３相交流のＷ相の正相通電を、「ｗ」はＷ相の逆相通電を表わす。
【００４０】
図４に示す様に、第１電磁石８の電気コイル８ａ〜８ｆ及び第４電磁石１１の電気コイル１１ａ〜１１ｆは、第２電源装置ＩＮＶ２のＵ，Ｖ，Ｗ相端子に接続されており、第２電磁石９の電気コイル９ａ〜９ｆ及び第３電磁石１０の電気コイル１０ａ〜１０ｆは、第１電源装置ＩＮＶ１のＵ，Ｖ，Ｗ相端子に接続されている。
【００４１】
第２電磁石９及び第３電磁石１０に流れる励磁電流をＩ１とし、第１電磁石８及び第４電磁石１１に流れる励磁電流をＩ２として、電流比αを、α＝Ｉ２／Ｉ１とすれば、流動溶鋼の起点側速度をＶｓ、終点側速度をＶｅとした時、流動駆動される溶融金属１の鋳型長辺４Ｆ，５Ａに沿う水平方向速度を、Ｖｓ≧Ｖｅにするために、０≦α≦０．５としている。
【００４２】
図５に、第２電磁石９と第３電磁石１０を励磁する第１電源装置ＩＮＶ１の構成を示す。３相交流電源（３相電力線）２１には直流整流用のサイリスタブリッジ２２Ａ1が接続されており、その出力（脈流）はインダクタ２５Ａ1およびコンデンサ２６Ａ1で平滑化される。平滑化された直流電圧は３相交流形成用のパワ−トランジスタブリッジ２７Ａ1に印加され、これが出力する３相交流Ｕ，Ｖ，Ｗ相が図４に示す結線に従って第２電磁石９と第３電磁石１０の各コイルに印加される。
【００４３】
第２電磁石９の電気コイル９ａ〜９ｆ及び第３電磁石１０の電気コイル１０ａ〜１０ｆが、図３に点線矢印で示す推力を発生するためのコイル電圧指令値ＶdcＡ１が位相角α算出器２４Ａ１に与えられ、位相角α算出器２４Ａ１が、指令値ＶdcＡ１に対応する導通位相角α（サイリスタトリガ−位相角）を算出し、これを表わす信号をゲ−トドライバ２３Ａ１に与える。ゲ−トドライバ２３Ａ１は、各相のサイリスタを、各相のゼロクロス点から位相カウントを開始して位相角αで導通トリガ−する。これにより、トランジスタブリッジ２７Ａ１には、指令値ＶdcＡ１が示す直流電圧が印加される。
【００４４】
一方、３相信号発生器３１Ａ１は、周波数指令値Ｆdcで指定された周波数(この実施例では５０Ｈｚ）の、定電圧３相交流信号を発生して、比較器２９Ａ１に与える。比較器２９Ａ１にはまた、三角波発生器３０Ａ１が３ＫＨｚの、定電圧三角波を与える。比較器２９Ａ１は、Ｕ相信号が正レベルのときには、それが三角波発生器３０Ａ１が与える三角波のレベル以上のとき高レベルＨ（トランジスタオン）で、三角波のレベル未満のとき低レベルＬ（トランジスタオフ）の信号を、Ｕ相の正区間宛て（Ｕ相正電圧出力用トランジスタ宛て）にゲ−トドライバ２８Ａ１に出力し、Ｕ相信号が負レベルのときには、それが三角波発生器３０Ａ１が与える三角波のレベル以下のとき高レベルＨで、三角波のレベルを越えるとき低レベルＬの信号を、Ｕ相の負区間宛て（Ｕ相負電圧出力用トランジスタ宛て）にゲ−トドライバ２８Ａ１に出力する。Ｖ相信号およびＷ相信号に関しても同様である。ゲ−トドライバ２８Ａ１は、これら各相，正，負区間宛ての信号に対応してトランジスタブリッジ２７Ａ１の各トランジスタをオン，オフ付勢する。
【００４５】
これにより、電源接続端子Ｕ１１には、３相交流のＵ相電圧が出力され、電源接続端子Ｖ１１に同様なＶ相電圧が出力され、また電源接続端子Ｗ１１に同様なＷ相電圧が出力され、これらの電圧の上ピ−ク／下ピ−ク間レベルはコイル電圧指令値ＶdcＡ１で定まる。この３相電圧の周波数はこの実施例では周波数指令値Ｆdcにより５０Ｈｚである。すなわち、コイル電圧指令値ＶdcＡ１で指定されたピ−ク電圧値（推力）の５０Ｈｚの３相交流電圧が、図４に示す第２電磁石９の電気コイル９ａ〜９ｆ、及び第３電磁石１０の電気コイル１０ａ〜１０ｆに印加される。
【００４６】
第１電磁石８及び第４電磁石１１の電気コイルに３相交流を流す、第２電源回路ＩＮＶ２の構成は、図５に示す上述のＩＮＶ１と同一であるが、コイル電圧指令値が異なる。すなわち、第１電磁石８の電気コイル８ａ〜８ｆ、及び第４電磁石１１の電気コイル１１ａ〜１１ｆが図４に点線矢印で示す推力を発生するためのコイル電圧指令値ＶdcＢ１がＶdcＡ１の代りに使用され、位相角α算出器２４Ａ１に与えられる。これらのコイル電圧指令値ＶｄｃＡ１およびコイル電圧指令値ＶｄｃＢ１は、鋳型長辺に沿って配置された２個の電磁石の励磁電流比αが、前述の０≦α≦０．５となる様に設定する。従って、起点側速度をＶｓ、終点側速度をＶｅとした時、流動駆動される溶融金属１の鋳型長辺４Ｆ，５Ａに沿う水平方向速度は、Ｖｓ≧Ｖｅを満足する。
【００４７】
この結果ノズル２からの噴出流と電磁石８〜１１の推力が総合された溶鋼流は、図３の（ｂ）に示すような実線矢印の大きさ及び方向となり、鋳型内壁に沿った循環流を形成する。また短辺に衝突する溶鋼流速が低下するので、上昇流(2)，(6)及び下降流(3)，(7)が低減し、メニスカス付近においても図３の（ｂ）に示すような鋳型内壁に沿った循環流を形成する。
【００４８】
図６及び図７にαの値を変化した場合の実施結果を示す。ＤＫＭは電磁石であり、ノズルは鋳型長辺方向を示す横軸の０．５ｍ位置にあって溶鋼を噴出し、流出口３のレベルは、メニスカス下略０．５ｍである。図６は、メニスカス部における溶鋼の水平方向速度成分の分布を示す。図に示す様に、α＝１とした時の横軸の０．８ｍ位置に認められる淀み域（ｙ方向流速が負）は、α＝０．５とした時に大幅に改善されている。図７は、メニスカス下１ｍにおける溶鋼の垂直方向速度分布の状態を示す。α＝１とした時に比較しα＝０．５とした時の方が上昇流、及び下降流が減少している。
【００４９】
−第２実施例−
図８の（ａ）に第２実施例における流出口３と大略同じ高さでの流出溶鋼流と、第１〜第４電磁石が発生する推力の状態を示す。第２実施例においても、鋳型ＭＤの長辺４Ｆの長手方向に沿って、かつ注入ノズル２の流出口３と大略同じ高さに電磁石８，９が、また鋳型ＭＤの長辺５Ａの長手方向に沿って、電磁石８，９と対向して２個の電磁石１０，１１が設けられており、これらがノズル２の流出口３と大略同じ高さの溶鋼１に電磁力を与える。しかし第１電磁石８及び第４電磁石１１が発生する推力方向を、第１実施例のそれと逆向にしている。すなわち第１電磁石８及び第４電磁石１１の発生する推力方向を流出口３から噴出する溶鋼流に対向する方向とする態様である。
【００５０】
図８の（ａ）に示すように、第１電磁石８の発生する推力は流出溶鋼流と対向して比較的小さく、第２電磁石９の発生する推力は流出溶鋼流と対向して比較的大きい。また第３電磁石１０の発生する推力は流出溶鋼流と対向して比較的大きく、第４電磁石１１の発生する推力は流出溶鋼流と対向して比較的小さい。この様に異なった大きさ及び方向の推力を発生するように、電磁石に通流する電流レベルを決定し、また電磁石コイルの結線を構成する。
【００５１】
図９に、図２に示す電磁石８の電気コイル８ａ〜８ｆ、電磁石９の電気コイル９ａ〜９ｆ、電磁石１０の電気コイル１０ａ〜１０ｆ、及び電磁石１１の電気コイル１１ａ〜１１ｆの結線および電源回路との接続態様を示す。
【００５２】
図９に示す各電磁石８〜１１の結線は２極（Ｎ＝２）のものであり、電気コイルに３相交流を通電する。図９に示す様に、第１電磁石８の電気コイル８ａ〜８ｆの結線と第３電磁石１０の電気コイル１０ａ〜１０ｆの結線は同様に接続されており、また第２電磁石９の電気コイル９ａ〜９ｆの結線と第４電磁石１１の電気コイル１１ａ〜１１ｆの結線も同様に接続されている。
【００５３】
第１電磁石８の電気コイル８ａ〜８ｆと第４電磁石１１の電気コイル１１ａ〜１１ｆは第２電源装置ＩＮＶ２のＵ，Ｖ，Ｗ相端子に接続されており、第２電磁石９の電気コイル９ａ〜９ｆと第３電磁石１０の電気コイル１０ａ〜１０ｆは第１電源装置ＩＮＶ１のＵ，Ｖ，Ｗ相端子に接続されている。第２電磁石９、及び第３電磁石１０に流れる励磁電流をＩ１とし、第１電磁石８、及び第４電磁石に流れる励磁電流をＩ２とすれば、長辺４Ｆに沿って配置された第１電磁石８と、第２電磁石９に流れる電流比αは、α＝Ｉ２／Ｉ１であり、同様に長辺５Ａに沿って配置された第４電磁石１１と、第３電磁石１０に流れる電流比αも、α＝Ｉ２／Ｉ１である。
【００５４】
第２実施例では流動溶鋼の起点側速度をＶｓ、終点側速度をＶｅとした時、流動駆動される溶融金属１の鋳型長辺４Ｆ，５Ａに沿う水平方向速度を、Ｖｓ≧Ｖｅにするために、０≦α≦０．５としており、かつ第１電磁石８、及び第４電磁石１１が発生する比較的小さい推力を、流出溶鋼流と対向する方向としている。
【００５５】
この結果、ノズル２からの噴出流と２個の電磁石の推力が加わった溶鋼流は、図８の（ｂ）に示すような鋳型内壁に沿った循環流を形成する。また短辺に衝突する溶鋼流が減少するので、上昇流(2)，(6)及び下降流(3)，(7)が低減し、メニスカス付近においても図８の（ｂ）に示すような鋳型内壁に沿った循環流を形成する。
【００５６】
他の部分は第１実施例と同様であるので説明を省略する。
【００５７】
−第３実施例−
図１０の（ａ）に第３実施例における流出口３と大略同じ高さでの流出溶鋼流と、第１〜第４電磁石が与える電磁力の状態を示す。第３実施例においても、鋳型ＭＤの長辺４Ｆの長手方向に沿って、かつ注入ノズル２の流出口３と大略同じ高さに電磁石８，９が、また鋳型ＭＤの長辺５Ａの長手方向に沿って、電磁石８，９と対向して２個の電磁石１０，１１が設けられており、これらがノズル２の流出口３と大略同じ高さの溶鋼１に電磁力を与える。しかし第１電磁石８及び第４電磁石１１を直流電源により励磁しており、第１電磁石８及び第４電磁石１１と対向する溶鋼に一定の磁束を加えている。該一定磁束中を溶鋼が流れると、溶鋼中に渦電流が発生するので、該渦電流により生ずる磁束と印加磁束と間に相互作用が働き、流動溶鋼に対し電磁ブレ−キ作用が働く。すなわち電磁石９，１０により流出口３から噴出する溶鋼流に対向する推力を加えて制動し、電磁石８，１１により流出口３から噴出する溶鋼流に対し電磁制動力を与える態様である。この様な大きさ及び方向の推力を発生するように電磁石に通流する電流レベルを決定し、また電磁石コイルの結線を構成する。
【００５８】
図１１に、図２に示す電磁石８の電気コイル８ａ〜８ｆ、電磁石９の電気コイル９ａ〜９ｆ、電磁石１０の電気コイル１０ａ〜１０ｆ、及び電磁石１１の電気コイル１１ａ〜１１ｆの結線および電源回路との接続状態を示す。
【００５９】
図１１に示す第１電磁石８の電気コイル８ａ〜８ｆと第４電磁石１１の電気コイル１１ａ〜１１ｆは、各巻線が直列に接続されており、これらの電気コイルには直流電源装置ＤＣＰＳから直流電流が供給されている。
【００６０】
電磁石９，１０の結線は２極（Ｎ＝２）のものであり、第２電磁石９の電気コイル９ａ〜９ｆと第３電磁石１０の電気コイル１０ａ〜１０ｆは第１電源装置ＩＮＶ１のＵ，Ｖ，Ｗ相端子に接続されている。
【００６１】
第３実施例では、流動溶鋼の起点側速度をＶｓ、終点側速度をＶｅとした時、流動駆動される溶融金属１の鋳型長辺４Ｆ，５Ａに沿う水平方向速度を、Ｖｓ≧Ｖｅにするために、第２電磁石９，及び第３電磁石の発生する推力を流出口からの噴出流と対向させており、かつ第１電磁石８，及び第４電磁石１１を電磁ブレ−キとして作動させている。この結果、ノズル２からの噴出流と２個の電磁石の推力が加わった溶鋼流は、図１０の（ｂ）に示すような鋳型内壁に沿った循環流を形成する。また短辺に衝突する溶鋼流が減少するので、上昇流(2)，(6)及び下降流(3)，(7)が低減し、メニスカス付近においても図１０の（ｂ）に示すような鋳型内壁に沿った循環流を形成する。他の部分は第１実施例と同様であるので説明を省略する。
【図面の簡単な説明】
【図１】本発明の流動制御装置を連続鋳造鋳型に適用した場合の縦断面図である。
【図２】図１に示す連続鋳造鋳型、及びその長辺に沿って配置された電磁石の構成を示す平面図である。
【図３】（ａ）は第１実施例における、ノズル流出口３からの噴出流と電磁石（リニアモ−タ）８〜１１が発生する推力の状態を示すベクトル図であり、（ｂ）は（ａ）の電磁石推力により、鋳型内壁に沿って生じる溶鋼の循環流の状態を示すベクトル図である。
【図４】第１実施例における、電磁石（リニアモ−タ）８〜１１の結線を示す電気回路図である。
【図５】図４に示す三相交流電源装置ＩＮＶ１の電気回路図である。
【図６】電流比αを変化させた時の、メニスカス部での溶鋼流速を示すグラフである。
【図７】電流比αを変化させた時の、メニスカス下１ｍでの溶鋼流速を示すグラフである。
【図８】（ａ）は第２実施例における、ノズル流出口３からの噴出流と電磁石（リニアモ−タ）８〜１１が発生する推力の状態を示すベクトル図であり、（ｂ）は（ａ）の電磁石推力により、鋳型内壁に沿って生じる溶鋼の循環流の状態を示すベクトル図である。
【図９】第２実施例における、電磁石（リニアモ−タ）８〜１１の結線を示す電気回路図である。
【図１０】（ａ）は第３実施例における、ノズル流出口３からの噴出流と第２，第３電磁石９，１０が発生する推力と、第１，第４電磁石８，１１が発生する溶鋼流制動力の状態を示すベクトル図であり、（ｂ）は（ａ）の電磁石推力により、鋳型内壁に沿って生じる溶鋼の循環流の状態を示すベクトル図である。
【図１１】第３実施例における、電磁石（リニアモ−タ）９，１０、及び電磁ブレ−キ８，１１の結線を示す電気回路図である。
【図１２】（ａ）は、鋳型及び注湯ノズルの断面と、注湯ノズルからの溶鋼注入により生ずる溶鋼流を示す縦断面図、（ｂ）は（ａ）のＣＣ線から見た、注湯ノズルからの溶鋼注入により生ずる溶鋼流を示す平面図、（ｃ）は注湯ノズルからの溶鋼注入により生ずる表層流を示す平面図である。
【図１３】従来使用されていたリニアモ−タＬＭ１〜ＬＭ４を備える鋳型，鋳型内溶鋼の表面に生ずる表層流（実線矢印）、リニアモ−タＬＭ１〜ＬＭ４が溶鋼に及ぼす推力（点線矢印）、及び溶鋼表面に誘起される循環流（２点線矢印）を示す平面図である。
【符号の説明】
１：溶鋼２：注湯ノズル
３：流出口４Ｆ：第１長辺
４ｓ：長辺外壁４ｕ：長辺内壁
５Ａ：第２長辺５ｓ：長辺外壁
５ｕ：長辺内壁６Ｌ：第１短辺
６ｓ：短辺外壁６ｕ：短辺内壁
７Ｒ：第２短辺７ｓ：短辺外壁
７ｕ：短辺内壁８：第１電磁石
８１：第１電磁石コア
８ａ〜８ｆ：第１電磁石の電気コイル
９：第２電磁石９１：第２電磁石コア
９ａ〜９ｆ：第２電磁石の電気コイル
１０：第３電磁石
１０１：第３電磁石コア
１０ａ〜１０ｆ：第３電磁石の電気コイル
１１：第４電磁石
１１１：第４電磁石コア
１１ａ〜１１ｆ：第４電磁石の電気コイル
ＤＣＰＳ：直流電源装置
ＩＮＶ１：第１三相交流電源装置
ＩＮＶ２：第２三相交流電源装置
ＬＭ１〜ＬＭ４：リニアモ−タ
ＭＤ：鋳型ＰＷ：パウダ[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a flow control device that drives a molten metal in a mold in horizontal circulation.
[0002]
[Prior art]
For example, in continuous casting, molten steel is poured into a mold from a tundish, and in the mold, the molten steel is drawn out while being gradually cooled from the mold wall surface. If the temperatures on the mold wall surfaces at the same height are not uniform, surface cracks and shell ruptures are likely to occur. In order to improve this, conventionally, a molten steel is flow-driven in a mold in parallel with the upper surface thereof along the wall of the mold using an electromagnet or a linear motor (for example, Japanese Patent Laid-Open No. 1-228645). If the flow speed of the molten steel at the surface layer of the molten steel is not uniform, the powder on the molten steel is caught in the molten steel, which becomes a defect in the slab. Molten steel is supplied to the mold from a tundish through a pouring nozzle, but the speed of the molten steel flowing into the mold is high, which tends to cause powder entrainment. In order to improve this, an electromagnetic brake device for applying a static magnetic field to molten steel has been proposed (for example, JP-A-3-258442).
[0003]
Although the flow driving of molten steel disclosed in Japanese Patent Application Laid-Open No. 1-228645 has a certain effect, the horizontal circulating flow along the mold wall surface is disturbed by the flow of molten steel flowing into the mold via the pouring nozzle. This type of flow drive uses a linear motor type electromagnet in which an electric coil is wound around each of a plurality of magnetic poles arranged along the long side of the mold, and the electric coil is provided for each of three phases. Are connected to each phase of the three-phase power supply with a phase shift of 120 ° in a bundled unit, and the voltage and / or frequency of the three-phase power supply is adjusted by an inverter or a cycloconverter, whereby the required Driving force and speed are obtained.
[0004]
FIG. 12 (a) shows a vertical cross-sectional view of the mold, and FIG. 12 (b) shows a plan view of molten steel in the mold by the CC-CC line of FIG. 12 (a), and FIG. Indicates a plane in which the upper surface (meniscus) of the molten steel in the mold is viewed from the upper surface of the mold. As shown by a solid line arrow in FIG. 12A, the molten steel 1 flows into the mold from the nozzle 2 through the outlet 3, and is ejected in the short side direction of the mold.(1),(Five)Spawn. FIG. 12B shows the molten steel flow spouted from the outlet 3 in a cross section including the outlet 3. Ejection flow from outlet 3(1),(Five)Is the upward flow that hits the short side of the mold 6L.(2) WhenDownward downward flow(3)And the upward flow that hits the mold short side 7R and goes upward.(6)And downward flow(7)It becomes. Upward flow(2),(6)However, in the meniscus, as shown by the solid arrow in FIG.(Four),(8)Is generated. This surface flow(Four),(8)Is easy to involve the powder PW on the meniscus into the molten steel 1. On the other hand, when the molten steel 1 changes to a solid, gas (bubbles) such as CO is generated. In addition, if the molten steel 1 stays in a part of the inner surface of the mold MD, the powder PW tends to remain on the molten steel 1 and, moreover, seizure which causes breakout is liable to occur. To prevent these, it is preferable to form a stable rectification on the surface layer.
[0005]
Therefore, conventionally, as shown in FIG. 13, linear motors LM1 to LM4 facing the outer surface of the mold are installed along the long side of the mold, and the electromagnetic driving force (thrust) in the direction indicated by the dotted arrow in the figure is applied to the surface. Circulating along the inner wall of the mold as shown by a two-dot chain line arrow in the figure.
[0006]
The electromagnetic driving force generated by the linear motor LM3 shown in FIG. 13 is in a direction from right to left as indicated by a dotted arrow in FIG.(8)And the molten steel is accelerated, but the electromagnetic driving force generated by the linear motor LM4 is directed in the direction facing the surface flow (4), and the molten steel is decelerated.
[0007]
The electromagnetic driving force generated by the linear motor LM2 is from left to right as indicated by the dotted arrow in FIG.(Four)And the molten steel is accelerated, but the electromagnetic driving force generated by the linear motor LM1 is(8)And the molten steel is decelerated.
[0008]
On the other hand, in an “electromagnetic brake device” proposed in Japanese Patent Application Laid-Open No. 3-258442, a pair of electromagnets having a width substantially equal to the width of the long side along the long side of the mold is used to move the mold under the meniscus. The electric coil is placed opposite to each other, and its electric coil is excited by a direct current. The molten steel flowing in the constant magnetic field (static magnetic field) generated by the electromagnet generates an electromotive force according to Fleming's right-hand rule, and a current circulating in the magnetic flux flows. A braking force acts to stop the flow, which is caused by the downward molten steel flow shown in FIG.(3),(7)To suppress the sinking of inclusions down due to the molten steel flows (3) and (7).
[0009]
[Problems to be solved by the invention]
The circulating flow (the direction indicated by the two-dot chain line arrow in FIG. 13) along the mold inner wall of the surface layer of the molten steel to be generated by the linear motors LM1 to LM4 is a surface flow.(Four),(8)Affected by In other words, strong surface flow (reversed flow)(Four),(8)Inhibits the circulating flow along the mold inner wall of the surface layer by the linear motors LM1 to LM4. Therefore, in order to form the circulation flow, a strong surface flow (reversed flow)(Four),(8)Therefore, a strong electromagnetic propulsion force is needed to cancel the above, and a strong exciting current must be supplied to the linear motors LM1 to LM4.
[0010]
Above strong surface flow (reversed flow)(Four),(8)Is the jet flow flowing out of the pouring nozzle outlet 3 of the nozzle 2 shown in FIG.(1),(Five)Strongly collides with the short sides 6L and 7R of the mold, causing a large upward flow.(2),(6)To occur.
[0011]
When the electromagnetic brake device is used alone, the effect of uniformizing the velocity of the molten steel flowing into the mold from the pouring nozzle 2 is recognized, but the molten steel is driven in the mold using a linear motor or the like. When used together with the device, the molten steel flow (circulation flow) by the drive device is also braked. That is, since the electromagnetic brake applies a braking force to the molten steel moving in the applied constant magnetic field, the molten steel flow flowing downward is(3),(7)In addition, the braking force acts on the molten steel circulating flow along the inner wall of the mold moving across the applied constant magnetic field.
[0012]
A flow control device of the present invention has a first object to measure a decrease in an upward flow and a downward flow generated in a mold, and to effectively drive flow of molten steel along an inner surface of a mold near a meniscus. The third object is to reduce the necessity of the braking by the electromagnetic brake for controlling the descending molten steel flow or to make the braking unnecessary.
[0013]
[Means for Solving the Problems]
The molten metal flow control device of the present invention,
(1The electromagnets (8 to 11), which are electromagnetic force generators, are arranged at substantially the same level as the outlet of the nozzle (2) for injecting the molten metal (1) into the mold (MD). It is arranged along the long sides (5A, 6L), and at the same level, the horizontal flow of the molten metal (1) is performed along the two long sides at the level. The starting-side velocity Vs, which is the horizontal velocity of the molten metal in the horizontal direction along the long side of the mold at the 1/4 long side width point, is 1 point along the long side of the mold from the short side of the end point side of the flow along each long side. An electromagnetic force that satisfies Vs ≧ Ve is applied to the molten metal (1) with respect to an end-point side velocity Ve, which is a horizontal velocity of the molten metal in the horizontal direction along the long side of the mold at the / 4 long side width point. .
[0014]
According to this, since the electromagnets (8 to 11) are arranged at substantially the same level as the outlet of the nozzle (2) for injecting the molten metal (1) into the mold (MD), the electromagnets (8 to 11) are ejected from the nozzle (2). Molten metal jet ((1),(Five)) Is subjected to electromagnetic force. Starting point of the horizontal flow of the molten metal along the long side of the mold The horizontal velocity of the molten metal at the 1/4 long side width point from the short side of the mold is defined as the starting side velocity (Vs). When the molten metal horizontal speed at the 1/4 long side width point from the end side mold short side is the end side speed (Ve), the thrust or the molten metal from the electromagnets (8 to 11) is applied so that Vs ≧ Ve. Apply braking force.
[0015]
In addition, in order to facilitate understanding, the symbols of the corresponding elements of the embodiment shown in the drawings and described later are added in the parentheses for reference.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
In a preferred embodiment of the present invention,
(2Also, the outline of the present invention will be described more specifically.
A first electromagnet (8) and a second electromagnet (9) arranged along the first long side (4F) of the mold (MD) and a third electromagnet (9) arranged along the second long side (5A) 10) and a fourth electromagnet (11); causing the second electromagnet (9) and the third electromagnet (10) to generate a horizontal moving magnetic field along the first long side (4F) and the second long side (5A). The first exciting means (INV1), and the first electromagnet (8) and the fourth electromagnet (11) for generating a moving magnetic field in the horizontal direction along the first long side (4F) and the second long side (5A). 2. An apparatus for controlling the flow of molten metal comprising two excitation means (INV2);
The first to fourth electromagnets (8 to 11) are arranged at substantially the same level as the outlet (3) of the nozzle (2) for injecting the molten metal (1) into the mold (MD),
The first electromagnet (8) and the second electromagnet (9) extend from the short side (6L) at the starting side of the horizontal flow along the first long side of the molten metal (1) horizontally circulated at the level to the first length. The starting-side velocity Vs, which is the horizontal velocity of the molten metal at the 1/4 long-side width point along the side (4F), extends from the end-side mold short side (7R) of the horizontal flow along the first long side to the first long side. With respect to the end point side velocity Ve which is the horizontal velocity of the molten metal at the 長 long side width point along, a thrust satisfying Vs ≧ Ve is applied to the molten metal, and
The third electromagnet (10) and the fourth electromagnet (11) are moved from the short side (7R) of the horizontal mold starting side along the second long side of the molten metal (1) driven horizontally at this level to the second long side. The starting-side velocity Vs, which is the horizontal velocity of the molten metal at the 1/4 long-side width point along the side (5A), extends from the end-side mold short side (6L) of the horizontal flow along the second long side to the second long side. Applies a thrust that satisfies Vs ≧ Ve to the molten metal with respect to the end-point side velocity Ve that is the molten metal horizontal velocity at the 長 long side width point along
It is characterized by the following.
[0017]
According to this, in order to flow-drive the molten metal (1) injected into the mold (MD) from the outlet (3), the first (MD) of the mold (MD) is substantially at the same level as the outlet (3). A first electromagnet (8) and a second electromagnet (9) are arranged along the long side (4F). Similarly, a third electromagnet (10) and a fourth electromagnet (11) are arranged along the second long side (5A). The second electromagnet (9) and the third electromagnet (10) are excited by the first exciting means (INV1), and the first electromagnet (8) and the fourth electromagnet (11) are excited by the second exciting means (INV2). Thus, the molten metal (1) in the mold (MD) is flow-driven. The molten metal (1) injected into the mold (MD) from the outlet (3) and the thrust of the electromagnets (8 to 11) arranged opposite to the outlet (3) at substantially the same level are generated by a combination of thrusts. A thrust or braking force is applied to the molten metal from the electromagnets (8 to 11) so that the horizontal velocity of the molten metal (1) along the long side of the mold is such that the starting-side velocity Vs ≧ the end-point velocity Ve.
[0018]
The starting side speed (Vs) is a molten metal horizontal speed at a 1/4 long side width point from the starting side short side of the mold on the long side of the mold, and the end point side speed (Ve) is an end point side of the long side of the mold. It is the molten metal horizontal speed at the point of 1/4 long side width from the short side of the mold.
[0019]
By setting Vs ≧ Ve, the molten metal jet ((1),(Five)) Collides with the short side of the mold,(2),(6)) And descending flow ((3),(7)) Can be reduced. Ascending flow of molten metal generated by colliding with the short side of the mold ((2),(6)) Reverses the direction below the molten metal meniscus in the mold, and the surface flow (reversed flow)(Four),(8)), But if Vs ≧ Ve, the rising flow of the molten metal ((2),(6)) Becomes smaller, so the reverse flow ((Four),(8)) Also becomes smaller. The flow drive of the molten metal (1) caused by the electromagnets (8 to 11) arranged facing each other along the long side of the mold is less affected by the reverse flow even below the meniscus, and therefore, the mold (MD) A circulating flow along the inner surface is realized. Since smooth rotation of the molten steel is performed in this manner, entrapment (intrusion) of foreign matter (inclusions) into the slab due to the projected flow of the molten metal (1) is suppressed, and the internal quality of the slab is reduced. improves.
[0020]
Downflow ((3),(7)) Is reduced, so that the necessity of the electromagnetic brake for suppressing the downward flow is reduced or the electromagnetic brake is not required.
[0021]
(3Also, the thrust generated by the first electromagnet (8) and the fourth electromagnet (11) is substantially the same, and the thrust generated by the second electromagnet (9) and the third electromagnet (10) is substantially the same. And, the thrust generated by the first electromagnet (8) and the fourth electromagnet (11) located on each end point side of each of the horizontal flows along the first long side and the second long side is the third thrust located on each starting point side. The thrust generated by the second electromagnet (9) and the third electromagnet (10) is smaller.
[0022]
According to this, molten steel (1) poured from an outlet (3) of a nozzle (2) arranged substantially at the center of a mold (MD) is ejected toward a first short side (6L). A stream ((1)) and a jet stream ((5)) flowing out toward the second short side (7R) are formed. The first to fourth electromagnets (8 to 11) are respectively provided with the jet flows (8 to 11) so that the horizontal velocity along the mold long side (4F, 5A) of the flow-driven molten metal (1) is Vs ≧ Ve.(1),(Five)) And a horizontal thrust in the direction opposite to that of That is, the jet flow ((1),(Five)).
[0023]
On the other hand, the magnitude of the thrust generated by the first electromagnet (8) and the fourth electromagnet (11) is the same, and the magnitude of the thrust generated by the second electromagnet (9) and the third electromagnet (10) is the same. And the magnitude of the thrust generated by the first electromagnet (8) and the fourth electromagnet (11) is set smaller than the magnitude of the thrust generated by the second electromagnet (9) and the third electromagnet (10). The difference causes a circulating molten steel flow along the inner wall of the mold (MD). By reducing the flow velocity of the jet flow in this way, the horizontal flow velocity ((1)) colliding with the short side (6L) is reduced, and the upward flow ((2)) And descending flow ((3)) Becomes smaller. Similarly, the horizontal flow velocity colliding with the short side (7R) ((Five)) Decreases and the upward flow ((6)) And descending flow ((7)) Becomes smaller.
[0024]
(4Further, in another embodiment of the present invention, the electromagnets (9, 10) arranged on the starting side of each of the horizontal flows along the first long side and the second long side use the molten metal (1) in the long side of the mold. (4F, 5A) is a linear motor driven in a horizontal flow along the (4F, 5A), and the electromagnets (8, 11) arranged at each end point are electromagnetic brakes that brake the horizontal movement of the molten metal (1). .
[0025]
According to this, the horizontal velocity along the mold long side (4F, 5A) of the flow-driven molten metal (1) is set, for example, along the first long side (4F) in order to satisfy Vs ≧ Ve. In the first electromagnet (8) and the second electromagnet (9), the second electromagnet (9) arranged on the starting point drives molten steel as a linear motor, and the first electromagnet (8) arranged on the end point is electromagnetically driven. The fluid steel is braked as a brake. As a result, the horizontal velocity that collides with the short side (7R) decreases, and the upward flow ((6)) And descending flow ((7)) Becomes smaller. Similarly, in the third electromagnet (10) and the fourth electromagnet (11) arranged along the second long side (5A), the third electromagnet (10) arranged on the starting point side drives molten steel as a linear motor. The fourth electromagnet (11) arranged on the end point side brakes the flowing molten steel as an electromagnetic brake. As a result, the horizontal velocity that collides with the short side (6 L) decreases, and the upward flow ((2)) And descending flow ((3)) Becomes smaller.
[0026]
(5Further, in another embodiment of the present invention, the exciting current of the electromagnets (9, 10) arranged at the starting points of the horizontal flows along the first long side and the second long side is set to I1, each end point side. When the exciting current of the disposed electromagnets (8, 11) is I2, the current ratio α = I2 / I1 is set to 0 ≦ α ≦ 0.5.
[0027]
According to this, in order to satisfy Vs ≧ Ve, for example, in the first electromagnet (8) and the second electromagnet (9) arranged along the first long side (4F), the second electromagnet arranged on the starting point side The molten metal (1) is driven by setting the exciting current of (9) to I1, and the exciting current of the first electromagnet (8) arranged at the end point is set to I2 to drive the molten metal (1). The current ratio α = I2 / I1 is set to 0 ≦ α ≦ 0.5. That is, a strong exciting current is applied to the second electromagnet (9) arranged on the starting point side to increase the thrust against the molten metal (1), and a weak exciting current is applied to the first electromagnet (8) arranged on the end point side. Reduces thrust on molten metal (1). As a result, the horizontal velocity that collides with the short side (7R) decreases, and the upward flow ((6)) And descending flow ((7)) Becomes smaller.
[0028]
Similarly, in the third electromagnet (10) and the fourth electromagnet (11) arranged along the second long side (5A), the exciting current of the third electromagnet (10) arranged on the starting point side is defined as I1 and the molten metal ( 1) is driven, and the molten metal (1) is driven with the exciting current of the fourth electromagnet (11) arranged on the end point side as I2. The current ratio α = I2 / I1 is set to 0 ≦ α ≦ 0.5. That is, a strong exciting current is applied to the second electromagnet (9) arranged on the starting point side to increase the thrust against the molten metal (1), and a weak exciting current is applied to the first electromagnet (8) arranged on the end point side. Reduces thrust on molten metal (1). As a result, the horizontal velocity that collides with the short side (6 L) decreases, and the upward flow ((2)) And descending flow ((3)) Becomes smaller.
[0029]
When the same usage as the conventional linear motors LM1 to LM4 shown in FIG. 13 is used, the current I1 flowing to the linear motors LM2 and LM3 arranged on the starting side and the current I1 flowing on the end side are arranged. Since the currents I2 flowing through the linear motors LM1 and LM4 are equal, α = I2 / I1 = 1. In this case, since the thrusts by the linear motors LM1 to LM4 are the same, the horizontal flow velocity colliding with the short side becomes faster, and therefore the upflow and downflow increase.
[0030]
According to the method of the present invention, the molten steel is circulated and driven in a plane substantially at the same level as the outlet (3) of the nozzle (2), and the upward flow and the downward flow from the level are suppressed. As a result, a stable horizontal circulation flow can be obtained at a relatively constant speed on the surface layer. As a result, the floating of bubbles is promoted, powder is not entrained in the molten metal (1), and the inner surface of the mold at substantially the same level as the outlet (3) of the nozzle (2) is wiped cleanly, so that the molten metal stays. And the seizure of the slab to the mold (MD) is reduced.
[0031]
Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.
[0032]
【Example】
-1st Example-
FIG. 1 shows a longitudinal section of a continuous casting mold MD provided with four sets of electromagnets (linear motors) 8 to 11 according to one embodiment of the present invention. The molten steel 1 is injected into the mold MD from above through the outlet 3 of the injection nozzle 2 downward (in the vertical direction z), and the meniscus (surface) of the molten steel 1 is covered with powder PW. The mold MD is cooled by a water box (not shown) and cooling water flowing through a water flow passage in the mold, and the molten steel 1 gradually solidifies toward the inside from a portion in contact with the cooled surface of the mold, and is continuously drawn as a slab. It is. However, since the molten steel 1 is poured into the mold MD through the injection nozzle 2, the molten steel 1 always exists in the mold MD.
[0033]
Linear motors 8 and 9 extend along the longitudinal direction of the long side 4F of the mold MD and substantially at the same height as the outlet 3 of the injection nozzle 2, and linear motors extend along the longitudinal direction of the long side 5A of the mold MD. Two linear motors 10 and 11 are provided opposite to the motors 8 and 9, which apply an electromagnetic force to the molten steel 1 having substantially the same height as the outlet 3 of the nozzle 2.
[0034]
FIG. 2 shows a plane (upper surface) of the mold MD shown in FIG. In FIG. 2, 4F and 5A are first and second long pieces of the continuous casting mold MD, 6L and 7R are first and second short pieces, and the molten steel 1 is passed through the injection nozzle 2 into the space surrounded by these. It is injected from the front side of the paper to the back side (from the top to the bottom in the vertical direction z). Each piece (4F, 5A, 6L, 7R) has an inner wall (4u, 5u, 6u, 7u) made of a copper plate and an outer wall (4s, 5s, 6s, 7s) made of a non-magnetic stainless steel plate. .
[0035]
In this embodiment, in order to drive the molten steel 1 in the mold along the mold long piece 4F in the direction from -y to + y (from the bottom to the top in the drawing), the molten steel 1 is short along the long side 4F of the mold MD. A relatively large thrust is applied by the three-phase linear motor type electromagnet 9 arranged on the side 6L side, and relatively three-phase linear motor type electromagnet 8 arranged on the short side 7R side along the long side 4F of the mold MD. Apply a small thrust. Similarly, a relatively large thrust is applied to the molten steel 1 in the mold by a three-phase linear motor type electromagnet 10 arranged on the short side 7R along the long side 5A of the mold and along the long side 5A of the mold MD. A relatively small thrust is applied by a three-phase linear motor type electromagnet 11 disposed on the short side 6L side.
[0036]
As shown in FIGS. 1 and 2, in the present embodiment, the core 81 of the electromagnet 8 has six slots, and each of the slots has an electric coil 8 a to 8 f inserted thereinto, thus forming a “body winding”. The electromagnet core 81 and the electric coils 8a to 8f are cooled and covered with a heat-resistant cover, but the cooling structure and the cover are not shown. The electromagnet core 81 has a comb shape having slots on the inside facing the mold MD. An electric coil is inserted into each slot, the end face of the convex portion between the slots forms a magnetic pole, and the end face is substantially the same as the outlet 3 of the nozzle 2. It faces the molten steel 1 at the same height. The other electromagnets 9, 10 and 11 have the same structure as the electromagnet 8.
[0037]
The electromagnets 8 to 11 are for applying a thrust (direction and magnitude) indicated by solid arrows shown in FIG. 3A to the molten steel 1. In this embodiment, the first electromagnet 8 and the second electromagnet 9 are used. Then, different levels of current are applied to the respective electromagnets so as to generate different thrusts, and so that the third electromagnet 10 and the fourth electromagnet 10 generate different thrusts. This content will be described later.
[0038]
FIG. 4 shows the connection and power supply circuit of the electric coils 8a to 8f of the electromagnet 8, the electric coils 9a to 9f of the electromagnet 9, the electric coils 10a to 10f of the electromagnet 10, and the electric coils 11a to 11f of the electromagnet 11 shown in FIG. Is shown. The connection of each of the electromagnets 8 to 11 shown in FIG. 4 is of two poles (N = 2), and a three-phase alternating current is supplied to the electric coil. For example, the electric coils 8a to 8f are denoted by u, u, V, V, w, w, U, U, v, v, W, W from left to right in FIG. V and v and W and w mean a winding start end and a winding end end of a set of coils wound around slots provided in the electromagnet core, respectively. When the U-phase of the three-phase AC power supply is connected to “U”, the positive-phase energization is performed. When the U-phase of the three-phase AC power supply is connected to “u”, the U-phase reverse-phase energization is performed. (180 ° phase shift from U phase).
[0039]
Similarly, “V” indicates V-phase normal-phase energization of three-phase AC, “v” indicates V-phase reverse-phase energization, “W” indicates W-phase positive-phase energization of three-phase AC, and “w” Represents reverse phase energization of the W phase.
[0040]
As shown in FIG. 4, the electric coils 8a to 8f of the first electromagnet 8 and the electric coils 11a to 11f of the fourth electromagnet 11 are connected to the U, V, W phase terminals of the second power supply device INV2. The electric coils 9a to 9f of the second electromagnet 9 and the electric coils 10a to 10f of the third electromagnet 10 are connected to the U, V, W phase terminals of the first power supply device INV1.
[0041]
If the exciting current flowing through the second electromagnet 9 and the third electromagnet 10 is I1, the exciting current flowing through the first electromagnet 8 and the fourth electromagnet 11 is I2, and the current ratio α is α = I2 / I1, the flowing molten steel Where Vs is the starting-point side speed and Ve is the end-point side speed, the horizontal speed along the mold long sides 4F, 5A of the molten metal 1 to be flow-driven is 0 ≦ α ≦ 0 in order to satisfy Vs ≧ Ve. .5.
[0042]
FIG. 5 shows a configuration of the first power supply device INV1 that excites the second electromagnet 9 and the third electromagnet 10. A thyristor bridge 22A1 for DC rectification is connected to the three-phase AC power supply (three-phase power line) 21, and its output (pulsating flow) is smoothed by the inductor 25A1 and the capacitor 26A1. The smoothed DC voltage is applied to a power transistor bridge 27A1 for forming a three-phase alternating current, and the three-phase alternating current U, V, and W phases output from this are connected to the second electromagnet 9 and the third electromagnet 10 according to the connection shown in FIG. Is applied to each coil.
[0043]
The electric coil 9a to 9f of the second electromagnet 9 and the electric coil 10a to 10f of the third electromagnet 10 provide the phase angle α calculator 24A1 with a coil voltage command value VdcA1 for generating a thrust indicated by a dotted arrow in FIG. Then, the phase angle α calculator 24A1 calculates the conduction phase angle α (thyristor trigger-phase angle) corresponding to the command value VdcA1, and supplies a signal representing this to the gate driver 23A1. The gate driver 23A1 starts the phase counting of the thyristor of each phase from the zero cross point of each phase and triggers conduction at the phase angle α. As a result, the DC voltage indicated by the command value VdcA1 is applied to the transistor bridge 27A1.
[0044]
On the other hand, the three-phase signal generator 31A1 generates a constant-voltage three-phase AC signal having a frequency (50 Hz in this embodiment) specified by the frequency command value Fdc, and supplies the signal to the comparator 29A1. A triangular wave generator 30A1 supplies a constant voltage triangular wave of 3 KHz to the comparator 29A1. When the U-phase signal is at a positive level, the comparator 29A1 is at a high level H (transistor on) when the level is equal to or higher than the level of the triangular wave provided by the triangular wave generator 30A1, and at a low level L (transistor off) when the level is lower than the level of the triangular wave. Is output to the gate driver 28A1 to the U-phase positive section (to the U-phase positive voltage output transistor). When the U-phase signal is at a negative level, the triangular wave level supplied by the triangular wave generator 30A1 is output. A signal of a high level H at the time below and a signal of a low level L when exceeding the level of the triangular wave is output to the gate driver 28A1 to the negative section of the U-phase (to the U-phase negative voltage output transistor). The same applies to the V-phase signal and the W-phase signal. The gate driver 28A1 turns on and off the transistors of the transistor bridge 27A1 in accordance with the signals addressed to each phase, positive and negative sections.
[0045]
As a result, a three-phase AC U-phase voltage is output to the power connection terminal U11, a similar V-phase voltage is output to the power connection terminal V11, and a similar W-phase voltage is output to the power connection terminal W11. The level between the upper and lower peaks of these voltages is determined by the coil voltage command value VdcA1. In this embodiment, the frequency of the three-phase voltage is 50 Hz according to the frequency command value Fdc. That is, the 50-Hz three-phase AC voltage of the peak voltage value (thrust) specified by the coil voltage command value VdcA1 is applied to the electric coils 9a to 9f of the second electromagnet 9 and the electric power of the third electromagnet 10 shown in FIG. It is applied to the coils 10a to 10f.
[0046]
The configuration of the second power supply circuit INV2 for supplying a three-phase alternating current to the electric coils of the first electromagnet 8 and the fourth electromagnet 11 is the same as the above-described INV1 shown in FIG. 5, but the coil voltage command value is different. That is, the coil voltage command value VdcB1 for the electric coils 8a to 8f of the first electromagnet 8 and the electric coils 11a to 11f of the fourth electromagnet 11 to generate a thrust indicated by a dotted arrow in FIG. 4 is used instead of VdcA1. , And the phase angle α calculator 24A1. The coil voltage command value VdcA1 and the coil voltage command value VdcB1 are set such that the exciting current ratio α of the two electromagnets arranged along the long side of the mold satisfies the aforementioned 0 ≦ α ≦ 0.5. . Therefore, when the starting point side speed is Vs and the end point side speed is Ve, the horizontal speed along the mold long sides 4F and 5A of the molten metal 1 driven to flow satisfies Vs ≧ Ve.
[0047]
As a result, the molten steel flow obtained by integrating the jet flow from the nozzle 2 and the thrust of the electromagnets 8 to 11 has the size and direction of the solid arrow as shown in FIG. 3B, and the circulating flow along the inner wall of the mold is formed. Form. Also, the flow velocity of molten steel colliding with the short side decreases,(2),(6)And descending flow(3),(7)And a circulating flow along the inner wall of the mold as shown in FIG. 3B is formed near the meniscus.
[0048]
FIGS. 6 and 7 show the results of implementation when the value of α is changed. DKM is an electromagnet. The nozzle is located at a position of 0.5 m on the horizontal axis in the direction of the long side of the mold and jets molten steel. The level of the outlet 3 is approximately 0.5 m below the meniscus. FIG. 6 shows the distribution of the horizontal velocity component of the molten steel in the meniscus portion. As shown in the figure, the stagnation area (the negative velocity in the y direction) observed at 0.8 m on the horizontal axis when α = 1 is greatly improved when α = 0.5. FIG. 7 shows a vertical velocity distribution of molten steel 1 m below the meniscus. The ascending flow and the descending flow are smaller when α = 0.5 than when α = 1.
[0049]
-2nd Example-
FIG. 8A shows the state of the outflow molten steel flow at substantially the same height as the outflow port 3 in the second embodiment and the thrust generated by the first to fourth electromagnets. Also in the second embodiment, the electromagnets 8 and 9 extend along the longitudinal direction of the long side 4F of the mold MD and at substantially the same height as the outlet 3 of the injection nozzle 2, and the longitudinal direction of the long side 5A of the mold MD. Along the line, two electromagnets 10 and 11 are provided facing the electromagnets 8 and 9, and these apply an electromagnetic force to the molten steel 1 having substantially the same height as the outlet 3 of the nozzle 2. However, the thrust directions generated by the first electromagnet 8 and the fourth electromagnet 11 are opposite to those of the first embodiment. That is, the thrust direction generated by the first electromagnet 8 and the fourth electromagnet 11 is set to a direction facing the molten steel flow ejected from the outlet 3.
[0050]
As shown in FIG. 8A, the thrust generated by the first electromagnet 8 is relatively small in opposition to the outflow molten steel flow, and the thrust generated by the second electromagnet 9 is relatively large in opposition to the outflow molten steel flow. . The thrust generated by the third electromagnet 10 is relatively large opposing the outflow molten steel flow, and the thrust generated by the fourth electromagnet 11 is relatively small opposing the outflow molten steel flow. The level of current flowing through the electromagnet is determined so as to generate thrusts having different magnitudes and directions, and the connection of the electromagnet coil is configured.
[0051]
FIG. 9 shows the connection and power supply circuit of the electric coils 8 a to 8 f of the electromagnet 8, the electric coils 9 a to 9 f of the electromagnet 9, the electric coils 10 a to 10 f of the electromagnet 10, and the electric coils 11 a to 11 f of the electromagnet 11 shown in FIG. Is shown.
[0052]
The connection of each of the electromagnets 8 to 11 shown in FIG. 9 has two poles (N = 2), and a three-phase alternating current is supplied to the electric coil. As shown in FIG. 9, the connection of the electric coils 8 a to 8 f of the first electromagnet 8 and the connection of the electric coils 10 a to 10 f of the third electromagnet 10 are similarly connected, and the electric coils 9 a to 9 f of the second electromagnet 9 are also connected. The connection of 9f and the connection of the electric coils 11a to 11f of the fourth electromagnet 11 are similarly connected.
[0053]
The electric coils 8a to 8f of the first electromagnet 8 and the electric coils 11a to 11f of the fourth electromagnet 11 are connected to the U, V, W phase terminals of the second power supply INV2, and the electric coils 9a to 9f of the second electromagnet 9 are connected. 9f and the electric coils 10a to 10f of the third electromagnet 10 are connected to the U, V, W phase terminals of the first power supply device INV1. Assuming that the exciting current flowing through the second electromagnet 9 and the third electromagnet 10 is I1, and the exciting current flowing through the first electromagnet 8 and the fourth electromagnet is I2, the first electromagnet 8 disposed along the long side 4F And the current ratio α flowing through the second electromagnet 9 is α = I2 / I1, and the current ratio α flowing through the fourth electromagnet 11 and the third electromagnet 10 similarly arranged along the long side 5A is also α = I2 / I1.
[0054]
In the second embodiment, when the starting-side speed of the fluidized molten steel is Vs and the end-point speed is Ve, the horizontal speed along the mold long sides 4F, 5A of the molten metal 1 to be flow-driven is Vs ≧ Ve. In addition, 0 ≦ α ≦ 0.5, and the relatively small thrust generated by the first electromagnet 8 and the fourth electromagnet 11 is set to the direction facing the outflow molten steel flow.
[0055]
As a result, the molten steel flow to which the jet flow from the nozzle 2 and the thrust of the two electromagnets are applied forms a circulating flow along the inner wall of the mold as shown in FIG. 8B. In addition, since the molten steel flow colliding with the short side is reduced, the ascending flows (2) and (6) and the descending flows (3) and (7) are reduced, and even near the meniscus, as shown in FIG. A circulating flow is formed along the inner wall of the mold.
[0056]
The other parts are the same as in the first embodiment, and the description is omitted.
[0057]
-Third embodiment-
FIG. 10A shows the flow of molten steel flowing out at substantially the same height as the outlet 3 in the third embodiment, and the state of the electromagnetic force provided by the first to fourth electromagnets. Also in the third embodiment, the electromagnets 8 and 9 are provided along the longitudinal direction of the long side 4F of the mold MD and substantially at the same height as the outlet 3 of the injection nozzle 2, and the longitudinal direction of the long side 5A of the mold MD. Along the line, two electromagnets 10 and 11 are provided facing the electromagnets 8 and 9, and these apply an electromagnetic force to the molten steel 1 having substantially the same height as the outlet 3 of the nozzle 2. However, the first electromagnet 8 and the fourth electromagnet 11 are excited by a DC power supply, and a certain magnetic flux is applied to the molten steel facing the first electromagnet 8 and the fourth electromagnet 11. When the molten steel flows in the constant magnetic flux, an eddy current is generated in the molten steel, so that an interaction acts between a magnetic flux generated by the eddy current and an applied magnetic flux, and an electromagnetic braking action acts on the flowing molten steel. In other words, the electromagnets 9 and 10 apply braking force to the molten steel flow ejected from the outlet 3 by applying opposing thrust, and apply the electromagnetic braking force to the molten steel flow ejected from the outlet 3 by the electromagnets 8 and 11. The level of the current flowing through the electromagnet is determined so as to generate a thrust of such magnitude and direction, and the connection of the electromagnet coil is configured.
[0058]
In FIG. 11, the connection and the power supply circuit of the electric coils 8 a to 8 f of the electromagnet 8, the electric coils 9 a to 9 f of the electromagnet 9, the electric coils 10 a to 10 f of the electromagnet 10, and the electric coils 11 a to 11 f of the electromagnet 11 shown in FIG. Shows the connection state of.
[0059]
The electric coils 8a to 8f of the first electromagnet 8 and the electric coils 11a to 11f of the fourth electromagnet 11 shown in FIG. 11 have respective windings connected in series, and these electric coils have a direct current from a DC power supply DCPS. Is supplied.
[0060]
The connection between the electromagnets 9 and 10 is two-pole (N = 2), and the electric coils 9a to 9f of the second electromagnet 9 and the electric coils 10a to 10f of the third electromagnet 10 are connected to the U and V of the first power supply device INV1. , W-phase terminals.
[0061]
In the third embodiment, when the starting side speed of the fluidized molten steel is Vs and the end side speed is Ve, the horizontal speed along the mold long sides 4F and 5A of the molten metal 1 to be flow-driven is Vs ≧ Ve. Therefore, the thrust generated by the second electromagnet 9 and the third electromagnet is opposed to the jet flow from the outlet, and the first electromagnet 8 and the fourth electromagnet 11 are operated as electromagnetic brakes. . As a result, the molten steel flow to which the jet flow from the nozzle 2 and the thrust of the two electromagnets are applied forms a circulating flow along the inner wall of the mold as shown in FIG. In addition, the flow of molten steel impinging on the short side is reduced,(2),(6)And descending flow(3),(7)And a circulating flow along the inner wall of the mold as shown in FIG. 10B is formed near the meniscus. The other parts are the same as in the first embodiment, and the description is omitted.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view when the flow control device of the present invention is applied to a continuous casting mold.
FIG. 2 is a plan view showing a configuration of a continuous casting mold shown in FIG. 1 and electromagnets arranged along a long side thereof.
FIG. 3A is a vector diagram showing a state of thrust generated by a jet flow from a nozzle outlet 3 and electromagnets (linear motors) 8 to 11 in the first embodiment, and FIG. It is a vector diagram which shows the state of the circulating flow of the molten steel generated along the inner wall of the mold by the electromagnet thrust of a).
FIG. 4 is an electric circuit diagram showing connection of electromagnets (linear motors) 8 to 11 in the first embodiment.
FIG. 5 is an electric circuit diagram of the three-phase AC power supply device INV1 shown in FIG.
FIG. 6 is a graph showing the flow rate of molten steel at the meniscus when the current ratio α is changed.
FIG. 7 is a graph showing the flow rate of molten steel 1 m below the meniscus when the current ratio α is changed.
FIG. 8A is a vector diagram showing a state of thrust generated by a jet flow from a nozzle outlet 3 and electromagnets (linear motors) 8 to 11 in the second embodiment, and FIG. It is a vector diagram which shows the state of the circulating flow of the molten steel generated along the inner wall of the mold by the electromagnet thrust of a).
FIG. 9 is an electric circuit diagram showing connection of electromagnets (linear motors) 8 to 11 in the second embodiment.
FIG. 10 (a) shows the jet flow from the nozzle outlet 3, the thrust generated by the second and third electromagnets 9, 10 and the first and fourth electromagnets 8, 11 in the third embodiment. It is a vector diagram which shows the state of the molten steel flow braking force, (b) is a vector diagram which shows the state of the circulating flow of the molten steel generated along the inner wall of the mold by the electromagnet thrust of (a).
FIG. 11 is an electric circuit diagram showing connection of electromagnets (linear motors) 9 and 10 and electromagnetic brakes 8 and 11 in the third embodiment.
12 (a) is a longitudinal sectional view showing a cross section of a mold and a pouring nozzle, and a molten steel flow generated by pouring molten steel from the pouring nozzle, and FIG. 12 (b) is a view taken from a CC line of FIG. FIG. 3C is a plan view illustrating a molten steel flow generated by injecting molten steel from a hot water nozzle, and FIG. 3C is a plan view illustrating a surface flow generated by injecting molten steel from a molten metal nozzle.
FIG. 13 shows a mold provided with conventional linear motors LM1 to LM4, a surface flow (solid arrow) generated on the surface of molten steel in the mold, a thrust exerted on molten steel by linear motors LM1 to LM4 (dotted arrow), and It is a top view which shows the circulating flow (two-dotted arrow) induced on the molten steel surface.
[Explanation of symbols]
1: molten steel 2: pouring nozzle
3: Outlet 4F: First long side
4s: Long side outer wall 4u: Long side inner wall
5A: 2nd long side 5s: Long side outer wall
5u: Long side inner wall 6L: First short side
6s: Short side outer wall 6u: Short side inner wall
7R: 2nd short side 7s: Short side outer wall
7u: Short side inner wall 8: First electromagnet
81: First electromagnet core
8a to 8f: electric coils of the first electromagnet
9: Second electromagnet 91: Second electromagnet core
9a to 9f: electric coil of second electromagnet
10: Third electromagnet
101: Third electromagnet core
10a to 10f: electric coil of third electromagnet
11: 4th electromagnet
111: 4th electromagnet core
11a to 11f: electric coil of fourth electromagnet
DCPS: DC power supply
INV1: first three-phase AC power supply
INV2: second three-phase AC power supply
LM1 to LM4: Linear motor
MD: Mold PW: Powder

Claims

An electromagnet, which is a generator of electromagnetic force, is disposed along two opposite long sides of the mold at substantially the same level as the outlet of the nozzle for injecting the molten metal into the mold, and at that level, horizontally along the two long sides. The origin side of the flow of the molten metal that is driven along the long side of the molten metal, which is the horizontal velocity of the molten metal in the horizontal direction along the long side of the mold at the point of 1/4 long side width along the long side from the short side of the mold. The end-point side velocity Ve in which the velocity Vs is the horizontal velocity of the molten metal in the horizontal direction along the mold long-side direction at the quarter-long side width point from the mold short side on the end point side of the flow along the long side to the mold long side. A flow control device for molten metal, wherein an electromagnetic force satisfying Vs ≧ Ve is applied to the molten metal.

A first electromagnet and a second electromagnet arranged along a first long side of the mold, and a third electromagnet and a fourth electromagnet arranged along a second long side; First exciting means for generating a horizontal moving magnetic field along the long side and the second long side, and generating a horizontal moving magnetic field along the first long side and the second long side on the first electromagnet and the fourth electromagnet. A second exciting means for causing the molten metal to flow;
The first to fourth electromagnets are arranged at substantially the same level as the outlet of the nozzle that injects the molten metal into the mold,
The first electromagnet and the second electromagnet are arranged at a 1/4 long side width point along the first long side from the mold short side on the starting side of the horizontal flow along the first long side of the molten metal driven horizontally at this level. The starting-side velocity Vs, which is the molten metal horizontal velocity, is the molten metal horizontal velocity at the 1/4 long-side width point along the first long side from the end-side mold short side of the horizontal flow along the first long side. A thrust that satisfies Vs ≧ Ve is applied to the molten metal with respect to the end point speed Ve, and
The third electromagnet and the fourth electromagnet are arranged at the 1/4 long side width point along the second long side from the starting short side of the mold along the second long side of the horizontal flow of the molten metal driven horizontally at the level. The starting-side velocity Vs, which is the molten metal horizontal velocity, is the molten metal horizontal velocity at the quarter-long width point along the second long side from the end-side mold short side of the horizontal flow along the second long side. A thrust that satisfies Vs ≧ Ve is given to the molten metal with respect to the end point speed Ve.
A flow control device for molten metal, comprising:

The thrust generated by the first electromagnet and the fourth electromagnet is substantially the same, the thrust generated by the second electromagnet and the third electromagnet is substantially the same, and each of the thrusts along the first long side and the second long side. The molten metal according to claim 2 , wherein the thrust generated by the first electromagnet and the fourth electromagnet located on each end point side of the horizontal flow is smaller than the thrust generated by the second electromagnet and the third electromagnet located on each start point side. Flow control device.

The electromagnets arranged at the starting points of the horizontal flows along the first long side and the second long side are linear motors for driving the molten metal to flow in the horizontal direction along the long sides of the mold, and are arranged at the end points. 3. The flow control device for molten metal according to claim 2 , wherein the electromagnet is an electromagnetic brake for braking the horizontal movement of the molten metal.

The ratio α = I2 / I1 of the exciting current I2 of the electromagnet arranged on each end point side to the exciting current I1 of the electromagnet arranged on each starting point side of each horizontal flow along the first long side and the second long side is 0 ≦ flow control apparatus for molten metal according to claim 2 or 3 wherein the alpha ≦ 0.5.