JPH10109148A - Method for controlling fluidity of molten steel in continuous casting mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling the fluidity of molten steel by which a cast slab clean over the whole width is obtained by securing magnetic braking force at short side parts of the cast slab in a static magnetic field type AC magnetic field. SOLUTION: In this method for regulating the spouting flow of molten steel 6 charged into the mold from an immersion nozzle 4 with the static magnetic field type AC magnetic field where different poles are opposed to each other generated between the magnetic poles 8 arranged over the whole body of the width direction of the cast slab on each back surface of the opposed long sides 2 of the mold by impressing an AC electric power, masking materials 10 consisting of a soft magnetic material are opposed across the long sides of the mold over the whole width at the outside in the width direction of the mold from the position near the short sides 3 between the long sides of the mold and the magnetic poles. Further, the opposed masking materials 10 are arranged by connecting with connecting materials 11 consisting of the soft magnetic material, and magnetic flux density is concentrated to the short side 3 parts of the cast slab.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、鋼の連続鋳造法に
おいて電磁力を用いた鋳型内溶鋼の流動制御方法に関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the flow of molten steel in a mold using electromagnetic force in a continuous casting method of steel.

【０００２】[0002]

【従来の技術】鋼の連続鋳造法において、浸漬ノズルか
ら鋳型内に注入された溶鋼の吐出流により、鋳型内溶鋼
は常に流動している。この流動速度が速くなると、脱酸
生成物であるアルミナを主体とする酸化物の鋳型内での
浮上分離が妨げられ、又、鋳型内溶鋼湯面に添加したモ
ールドパウダーが溶鋼中に巻き込まれ、そしてこれらは
非金属介在物として鋳片中に残留し、製品において致命
的な品質欠陥となる。2. Description of the Related Art In a continuous casting method of steel, molten steel in a mold always flows due to a discharge flow of molten steel injected into a mold from an immersion nozzle. When this flow rate is increased, the floating separation of the oxide mainly composed of alumina as a deoxidation product in the mold is hindered, and the mold powder added to the molten steel surface in the mold is caught in the molten steel, These remain as non-metallic inclusions in the slab, resulting in fatal quality defects in products.

【０００３】この現象は鋳造速度の増速に伴う吐出流速
度の高速度化や、浸漬ノズル内又は浸漬ノズル吐出孔に
アルミナが付着し、左右の吐出流速が不均一となる、所
謂、偏流が発生した場合に顕著となっている。[0003] This phenomenon is caused by so-called drifting, in which the discharge flow speed is increased with an increase in the casting speed, and alumina adheres to the inside of the immersion nozzle or the immersion nozzle discharge hole, and the left and right discharge flow rates become uneven. It is remarkable when it occurs.

【０００４】この対策として、電磁力（Electro-magnet
ic force）を用いて溶鋼流動を制御しようとする試みが
数多く提案されている。As a countermeasure against this, an electromagnetic force (Electro-magnet
Many attempts have been made to control molten steel flow using ic force).

【０００５】特開平３−１４２０４９号公報（以下、
「先行技術１」と記す）には、対向する鋳型長辺各背面
の上下に設置した上下各一対の磁極の間で鋳片の幅全体
にわたり静磁界を印加させ、吐出流を磁界で減速させる
方法が開示されている。[0005] Japanese Patent Application Laid-Open No. 3-14049 (hereinafter, referred to as "
According to “Prior art 1”, a static magnetic field is applied across the entire width of a slab between a pair of upper and lower magnetic poles provided above and below each back surface of a long side of a facing mold, and the discharge flow is decelerated by the magnetic field. A method is disclosed.

【０００６】特開平１−１５０４５０号公報（以下、
「先行技術２」と記す）には、メニスカスの下１．５ｍ
から４．０ｍの鋳造方向下方の位置に、直流磁界もしく
は低周波交流磁界を印加させ、磁界を通過する溶鋼流動
を減速・分散させる技術が開示されている。[0006] Japanese Patent Application Laid-Open No. 1-150450 (hereinafter referred to as
1.5 m below the meniscus
A technique of applying a DC magnetic field or a low-frequency AC magnetic field to a position 4.0 m below the casting direction to reduce and disperse the flow of molten steel passing through the magnetic field is disclosed.

【０００７】又、先行技術１、２は磁界は移動しない静
止型磁界であるのに対し、特開平５−２３８０４号公報
（以下、「先行技術３」と記す）には、低周波の交流電
源による移動磁界を用いる技術が開示されている。先行
技術３では鋳型長辺背面にリニア移動磁界発生装置を配
置し、浸漬ノズルからの溶鋼の吐出流方向と反対方向に
磁界を移動させることで溶鋼を磁界の移動方向に移動さ
せ、溶鋼の吐出流速度を減速させている。しかし、先行
技術３は、溶鋼の撹拌技術を流動制御に応用したもので
あり、主として磁界の移動方向しか制動力が作用しない
ため、流動制御手法としては不十分である。更に、磁界
が強すぎる場合には、流れの回り込みが発生したり、移
動磁界による付随流れを発生させるため、浸漬ノズルか
らの吐出流速と磁界強度とのバランスがくずれた場合に
は、制動効果よりも攪拌効果が優勢になるため、モール
ドパウダー巻き込みを助長する場合も起こり得る。この
ように、移動磁界を用いる方法は、鋳型内溶鋼の流動制
御方法としては最適な方法ではない。The prior arts 1 and 2 are static magnetic fields in which the magnetic field does not move. On the other hand, Japanese Patent Laid-Open No. 23804/1993 (hereinafter referred to as "prior art 3") discloses a low-frequency AC power supply. A technique using a moving magnetic field according to US Pat. In Prior Art 3, a linear moving magnetic field generator is disposed on the back side of the long side of the mold, and the magnetic field is moved in the direction opposite to the direction of the flow of molten steel discharged from the immersion nozzle, thereby moving the molten steel in the direction of movement of the magnetic field. The flow velocity has been reduced. However, prior art 3 is an application of molten steel stirring technology to flow control, and the braking force acts mainly only in the moving direction of the magnetic field, and thus is insufficient as a flow control method. Furthermore, if the magnetic field is too strong, the flow wraps around or generates an accompanying flow due to the moving magnetic field, so if the balance between the discharge velocity from the immersion nozzle and the magnetic field strength is lost, the braking effect will be reduced. Also, since the stirring effect becomes dominant, the entrainment of mold powder may be promoted. Thus, the method using the moving magnetic field is not an optimal method for controlling the flow of the molten steel in the mold.

【０００８】[0008]

【発明が解決しようとする課題】先行技術１は、鋳片の
全幅にわたって磁界を配置することで、吐出流の局所に
磁界を配置した場合に発生する溶鋼流の局部的な回り込
みを防止している。しかし、先行技術１においても磁力
が強過ぎる場合には、上下の磁界の谷間に沿って水平方
向に溶鋼流が走り、この溶鋼流は短辺凝固シェルに衝突
した時点で流れ方向を変え、下降流となる。鋳片と鋳型
壁とはモールドパウダーにより電気的に絶縁状態にある
ため、鋳片の端部である短辺近傍では誘導電流が逆向き
に流れて下降流を加速する方向に電磁力が作用し、下降
流は未凝固層深くまで侵入する。その結果、鋳片の幅方
向中央部の品質は向上するものの、短辺近傍部は品質が
劣化する。The prior art 1 disposes a magnetic field over the entire width of a slab, thereby preventing a local sneak of a molten steel flow generated when a magnetic field is disposed locally in a discharge flow. I have. However, even in the prior art 1, when the magnetic force is too strong, the molten steel flow runs horizontally along the valleys of the upper and lower magnetic fields, and the molten steel flow changes its flow direction when it collides with the short-side solidified shell, and descends. It becomes a flow. Since the slab and the mold wall are electrically insulated by the mold powder, the induced current flows in the opposite direction near the short side, which is the end of the slab, and an electromagnetic force acts in a direction to accelerate the downward flow. The descending flow penetrates deep into the unsolidified layer. As a result, the quality of the slab at the center in the width direction is improved, but the quality near the short side is deteriorated.

【０００９】先行技術２では、溶鋼への制動力の発生手
段として、直流磁界に代わって、低周波の交流磁界を用
いる方法も開示している。交流磁界の場合は、準静的な
誘導電流が存在しないため、先行技術１で発生する鋳片
短辺近傍での下降流を助長する現象は発生しない。Prior Art 2 also discloses a method of using a low-frequency AC magnetic field instead of a DC magnetic field as a means for generating a braking force on molten steel. In the case of an AC magnetic field, since there is no quasi-static induced current, a phenomenon that promotes a downward flow near the short side of the slab, which occurs in the prior art 1, does not occur.

【００１０】しかし交流磁界の場合、印加する電流の周
波数に応じて磁界の方向と誘導電流の方向とは１８０度
変化するものの、磁気による制動力の方向は変わらない
ため流動制御が可能であるが、この制動力は印加する電
流値に比例し最大から零まで周期的に変化することにな
る（以下、この磁界が移動しない交流磁界を「磁界静止
型交流磁界」と定義する）。However, in the case of an AC magnetic field, although the direction of the magnetic field and the direction of the induced current change by 180 degrees according to the frequency of the applied current, the flow control is possible because the direction of the braking force by magnetism does not change. This braking force is proportional to the applied current value and periodically changes from a maximum to zero (hereinafter, an AC magnetic field in which this magnetic field does not move is defined as a "magnetic field static AC magnetic field").

【００１１】先行技術２では、印加する電流の周波数が
一定で且つ１Ｈｚ未満の低周波であるので、磁気制動さ
れた溶鋼流は、溶鋼流の慣性力のために印加される電流
の周波数で変動する。その結果、その変動がメニスカス
部まで及ぶ高速鋳造の場合、電磁力制御によって逆にメ
ニスカスが乱れ、パウダーの巻き込みを助長する。In the prior art 2, since the frequency of the applied current is constant and low frequency of less than 1 Hz, the magnetically damped molten steel flow varies at the frequency of the applied current due to the inertia force of the molten steel flow. I do. As a result, in the case of high-speed casting in which the variation extends to the meniscus portion, the meniscus is disturbed by the electromagnetic force control, and the entrainment of the powder is promoted.

【００１２】又、磁界静止型交流磁界においては、鋳片
の短辺側では溶鋼中の誘導電流がサーキットを形成し
て、誘導電流の流れる方向が水平から垂直に変化するの
で、磁界による溶鋼流動の制動力が低下する。In a magnetic field static AC magnetic field, on the short side of the slab, the induced current in the molten steel forms a circuit, and the flowing direction of the induced current changes from horizontal to vertical. Braking force decreases.

【００１３】更に、対向する磁極で発生する磁束密度の
分布は磁極の中央部が高く、磁束の方向が分散する周辺
部は低く、従って、連続鋳造機において磁場印加装置が
鋳片の全幅にわたり配置されたとしても、磁極周辺部の
磁束密度の低い範囲を回避するには鋳型幅の約１．５倍
以上の磁場印加装置の幅が必要となり、そのため一般的
に通常の連続鋳造機においては、鋳片短辺部の磁束密度
が低くなっている。Further, the distribution of the magnetic flux density generated at the opposed magnetic poles is high in the central portion of the magnetic pole and low in the peripheral portion where the direction of the magnetic flux is dispersed. Therefore, in a continuous casting machine, the magnetic field applying device is arranged over the entire width of the slab. Even if it is done, in order to avoid the low range of the magnetic flux density around the magnetic pole, the width of the magnetic field applying device that is about 1.5 times or more of the mold width is required, and therefore, in a general continuous casting machine, generally, The magnetic flux density at the short side of the slab is low.

【００１４】このように鋳片短辺部は磁束密度も低下す
るので、前述の誘導電流の流れる方向の変化と相乗し、
磁界による溶鋼流動の制動力が一層低下する。その結
果、溶鋼吐出流の制動が十分でなく、鋳片、特に短辺側
で非金属介在物量が十分に低減されていない。Since the short side of the slab also has a reduced magnetic flux density, it is synergistic with the above-described change in the direction in which the induced current flows.
The braking force of the molten steel flow by the magnetic field is further reduced. As a result, the braking of the molten steel discharge flow is not sufficient, and the amount of nonmetallic inclusions on the slab, particularly on the short side, is not sufficiently reduced.

【００１５】本発明は上記事情に鑑みなされたもので、
その目的とするところは磁界静止型交流磁界における鋳
片短辺部の磁気制動力を確保し、鋳片全幅にわたり清浄
な鋳片を得るための溶鋼流動制御方法を提供するもので
ある。The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a method for controlling a flow of molten steel for securing a magnetic braking force at a short side portion of a slab in a magnetic field static type alternating magnetic field and obtaining a clean slab over the entire width of the slab.

【００１６】[0016]

【課題を解決するための手段】本発明の連続鋳造鋳型内
溶鋼の流動制御方法は、交流電源を印加して、対向する
鋳型長辺の各背面に鋳片幅方向全体にわたって配置され
た磁極間に異極が対向する磁界静止型交流磁界を発生さ
せ、この磁界静止型交流磁界により浸漬ノズルから鋳型
内に注入される溶鋼吐出流を制動する鋳型内溶鋼の流動
制御方法において、軟質磁性材料からなるマスキング材
を、鋳型長辺と磁極との間に鋳型短辺近傍位置から鋳型
幅方向外側の全幅にわたって鋳型長辺を挟んで対向し、
且つ対向するマスキング材を軟質磁性材料にて連結して
設置し、磁束密度を鋳片短辺部分に集中させることを特
徴とするものである。According to the present invention, there is provided a method for controlling the flow of molten steel in a continuous casting mold according to the present invention. In the flow control method of molten steel in a mold, which generates a magnetic field static type alternating magnetic field in which different poles are opposed to each other and brakes the molten steel discharge flow injected from the immersion nozzle into the mold by the magnetic field static type alternating magnetic field, The masking material becomes opposed between the long side of the mold and the magnetic pole with the long side of the mold interposed across the entire width in the outer side in the width direction of the mold from a position near the short side of the mold,
In addition, a masking material opposed to the slab is connected by a soft magnetic material, and the magnetic flux density is concentrated on the short side of the slab.

【００１７】鋳型長辺背面に配置された磁界静止型交流
磁界を発生する磁極にて鋳型長辺を貫く磁束を印加する
と、鋳型中に誘導電流が生起される。図２は鋳型中に生
起した誘導電流の流れる様子の例を模式的に示したもの
で、軟質磁性材料からなるマスキング材の無い場合は、
図２（ａ）に示すように水平方向に流れた誘導電流は、
鋳型長辺の幅方向端部でサーキットを形成して反転し、
水平方向反対側への流れとなり、鋳型長辺中で閉回路を
形成する。When a magnetic flux that penetrates the long side of the mold is applied by the magnetic pole that generates the static magnetic field of an alternating magnetic field arranged on the back side of the long side of the mold, an induced current is generated in the mold. FIG. 2 schematically shows an example of the appearance of the induced current generated in the mold. In the case where there is no masking material made of a soft magnetic material,
The induced current flowing in the horizontal direction as shown in FIG.
Form a circuit at the width direction end of the long side of the mold and flip it,
The flow is to the opposite side in the horizontal direction, and a closed circuit is formed in the long side of the mold.

【００１８】これに対し、軟質磁性材料からなるマスキ
ング材を鋳型長辺と磁極との間に鋳型短辺近傍位置から
鋳型幅方向外側の全幅にわたって対向し、且つ対向する
マスキング材を軟質磁性材料にて連結して設置すると、
鋳型中の誘導電流は鋳型長辺の幅方向端部まで流れるこ
となく、図２（ｂ）のように、マスキング材を設置した
位置でサーキットを形成して反転し、鋳片短辺部分に対
応する位置が鋳型中の誘導電流の端部となるので、この
部分の鋳型中を流れる誘導電流による誘導磁場は鋳型幅
方向の他の部分に比較して小さくなる。磁界静止型交流
磁界の磁極から発生し鋳型長辺を貫通する磁束密度は、
鋳型中の誘導電流による誘導磁場と干渉し減衰するが、
この部分の誘導磁場が小さくなるので磁束の減衰量が少
なくなり、鋳型短辺部分において鋳型長辺を貫通する磁
束密度が大きくなり、集中させることができる。これ
は、鋳型と鋳型内部の鋳片とはモールドパウダーにより
絶縁されているため、鋳型中に発生した誘導電流は鋳片
に流れることがないので、鋳片は鋳型中に発生する誘導
電流により生じる誘導磁場の影響を受けるためである。On the other hand, a masking material made of a soft magnetic material is opposed between the long side of the mold and the magnetic pole from the position near the short side of the mold over the entire width outside the mold in the width direction of the mold. When connected and installed,
The induced current in the mold does not flow to the width direction end of the long side of the mold, but forms a circuit at the position where the masking material is installed as shown in FIG. Since the position where the current flows is the end of the induced current in the mold, the induced magnetic field due to the induced current flowing in the mold in this portion is smaller than in other portions in the mold width direction. The magnetic flux density generated from the magnetic pole of the static magnetic field alternating magnetic field and penetrating the long side of the mold is
Interferes with the induced magnetic field due to the induced current in the mold and attenuates,
Since the induction magnetic field in this part is small, the attenuation of the magnetic flux is small, and the magnetic flux density penetrating the long side of the mold at the short side of the mold is large, so that it can be concentrated. This is because the mold and the slab inside the mold are insulated by the mold powder, so the induced current generated in the mold does not flow through the slab, so the slab is generated by the induced current generated in the mold This is because it is affected by the induction magnetic field.

【００１９】磁界による溶鋼流動の制動力は、溶鋼中の
磁界強度と溶鋼中の誘導電流値の積に比例する。本願発
明のマスキング材の設置により鋳片短辺部分の磁界強度
を上昇させることができるので、鋳片短辺部分の磁気制
動力を確保することができ、鋳片幅方向の磁気制動力を
均一化することができる。The braking force of the molten steel flow by the magnetic field is proportional to the product of the magnetic field strength in the molten steel and the induced current value in the molten steel. By installing the masking material of the present invention, it is possible to increase the magnetic field strength in the short side of the slab, so that the magnetic braking force in the short side of the slab can be secured, and the magnetic braking force in the slab width direction can be made uniform. Can be

【００２０】マスキング材は、純鉄、磁性鋼、珪素
鋼、Ｎｉを３０〜８０ｗｔ％含有したパーマロイと呼
ばれるＦｅ−Ｎｉ合金、フェライトと呼ばれＦｅ₂ Ｏ
₃ を主成分とする酸化物、非晶質金属等の所謂、軟質
磁性材料で構成する。これらの材料は、飽和磁束密度が
高く、保持力が低く、最大透磁率が高いので、磁気シー
ル効果が確保されるためである。The masking material is pure iron, magnetic steel, silicon steel, a Fe-Ni alloy called Permalloy containing 30 to 80% by weight of Ni, and Fe ₂ O called ferrite.
_It is composed of a so-called soft magnetic material such as an oxide containing ₃ as a main component and an amorphous metal. These materials have a high saturation magnetic flux density, a low coercive force, and a high maximum magnetic permeability, so that a magnetic sealing effect is ensured.

【００２１】磁界静止型交流磁界は浸漬ノズルからの溶
鋼吐出流を制動するため、磁界の鋳造方向の中心位置が
浸漬ノズル吐出孔より鋳造方向下方となるように設置す
るが、一段の磁界配置では不十分の場合は、必要に応じ
て複数段の磁界静止型交流磁界を浸漬ノズル吐出孔の下
方に並べて配置してもよい。In order to brake the molten steel discharge flow from the immersion nozzle, the static magnetic alternating magnetic field is installed so that the center position of the magnetic field in the casting direction is lower than the discharge hole of the immersion nozzle in the casting direction. If insufficient, a plurality of stages of static magnetic alternating magnetic fields may be arranged below the immersion nozzle discharge holes as needed.

【００２２】又、鋳片短辺部分の溶鋼の下降流を制動す
ることで、鋳片短辺部分の上昇流が強くなる場合には、
浸漬ノズル吐出孔より鋳造方向上方に、磁界静止型交流
磁界又は直流静磁界を設置し、上昇流も同時に制動して
も良い。Further, when the descending flow of the molten steel on the short side of the slab is braked to increase the upward flow on the short side of the slab,
A static magnetic field type alternating current magnetic field or direct current static magnetic field may be installed above the immersion nozzle discharge hole in the casting direction, and the upward flow may be simultaneously braked.

【００２３】[0023]

【発明の実施の形態】本発明の実施の形態を図面により
説明する。図１は本発明を適用した鋳片断面が矩形型の
連続鋳造機鋳型部分の概要を示したもので、（ａ）は側
面からみた概要図、（ｂ）は平面からみた概要図であ
る。Embodiments of the present invention will be described with reference to the drawings. FIGS. 1A and 1B schematically show a mold portion of a continuous casting machine having a rectangular cross section of a cast slab to which the present invention is applied, wherein FIG. 1A is a schematic diagram viewed from a side, and FIG. 1B is a schematic diagram viewed from a plane.

【００２４】連続鋳造用鋳型１は、対向する１対の鋳型
長辺２と鋳型長辺２内を摺動する１対の鋳型短辺３とか
らなり、溶鋼６は、図示せぬタンディッシュからタンデ
ィッシュ底部に取り付けた浸漬ノズル４を介して鋳型１
内に注入される。浸漬ノズル４の下端部は鋳型１内の溶
鋼６に浸漬され、溶鋼６は浸漬ノズル４の左右一対の吐
出孔５から鋳型短辺３に向けて吐出される。そして、溶
鋼６は鋳型１内で冷却され凝固して、鋳片７として連続
的に下方に引き抜かれる。The continuous casting mold 1 is composed of a pair of opposed mold long sides 2 and a pair of mold short sides 3 sliding within the mold long side 2. The molten steel 6 is formed from a tundish (not shown). The mold 1 is immersed through the immersion nozzle 4 attached to the bottom of the tundish.
Injected into. The lower end of the immersion nozzle 4 is immersed in the molten steel 6 in the mold 1, and the molten steel 6 is discharged from the pair of left and right discharge holes 5 of the immersion nozzle 4 toward the short side 3 of the mold. Then, the molten steel 6 is cooled and solidified in the mold 1, and is continuously drawn downward as a slab 7.

【００２５】鋳型長辺２の各背面には磁極８、８が鋳片
幅方向全体にわたって配置され、磁極８、８の鋳造方向
の中心位置は、浸漬ノズル４の吐出孔５より鋳造方向下
方の位置である。磁極８、８は鋳型１の側部を通るリタ
ーンヨーク１２で繋がり、磁極８、８にはコイル９が巻
かれ、鋳型長辺２を対向して設置した磁極８、８が異極
となるように、コイル９には図示せぬ交流電源装置から
交流電源が印加される。そして、磁極８、８は印加する
交流電源の周波数に従い極性を変化させる。Magnetic poles 8, 8 are arranged on the back side of the long side 2 of the mold over the entire width of the slab. The center position of the magnetic poles 8, 8 in the casting direction is lower than the discharge hole 5 of the immersion nozzle 4 in the casting direction. Position. The magnetic poles 8, 8 are connected by a return yoke 12 passing through the side of the mold 1. A coil 9 is wound around the magnetic poles 8, 8, so that the magnetic poles 8, 8 installed with the long sides 2 of the mold facing each other become different poles. Then, an AC power supply is applied to the coil 9 from an AC power supply device (not shown). The polarity of the magnetic poles 8 changes according to the frequency of the AC power supply to be applied.

【００２６】鋳型１の幅方向両端部の鋳型長辺２と磁極
８との間に、鋳型短辺３近傍位置から鋳型幅方向外側の
全幅にわたって鋳型長辺２を挟んで対向する位置にマス
キング材１０を配置する。そして対向するマスキング材
１０を連結材１１にて連結する。尚、マスキング材１０
と連結材１１とが、一体であっても本発明の実施に何ら
支障はない。マスキング材１０と鋳型短辺３との鋳型幅
方向の位置関係は、マスキング材１０の鋳型中央側端面
１０ａが鋳型短辺３の稼働面と略同一とすることが望ま
しい。略同一でない場合でも、マスキング材１０の鋳型
中央側端面１０ａは、鋳型短辺３の稼働面に対し、１０
０ｍｍ以内の位置に設置する必要がある。これは鋳型中
央側端面１０ａが鋳型短辺３の稼働面と離れ過ぎると、
鋳片短辺への磁束密度の集中が期待できなくなるためで
ある。A masking material is provided between the mold long side 2 and the magnetic pole 8 at both ends in the width direction of the mold 1 so as to oppose each other across the mold long side 2 from the position near the short side 3 of the mold over the entire width outside in the mold width direction. 10 is arranged. Then, the opposing masking materials 10 are connected by a connecting material 11. In addition, the masking material 10
Even if the and the connecting member 11 are integrated, there is no problem in implementing the present invention. Regarding the positional relationship between the masking material 10 and the mold short side 3 in the mold width direction, it is preferable that the end face 10a on the center side of the mold of the masking material 10 is substantially the same as the working surface of the mold short side 3. Even if they are not substantially the same, the end face 10a on the center side of the mold of the masking material 10 is
It must be installed at a position within 0 mm. This is because if the mold center side end surface 10a is too far from the working surface of the mold short side 3,
This is because concentration of magnetic flux density on the short side of the slab cannot be expected.

【００２７】マスキング材１０の鋳造方向長さは磁極８
の鋳造方向長さと同等以上とし、磁極８の鋳造方向全長
を覆うことが望ましい。そして鋳造幅の変更時にはマス
キング材１０は、鋳型短辺３と同期して移動するか、若
しくはマスキング材１０の配置位置を鋳片幅の変更毎に
変更して、常に設置位置が上記の範囲を満足するように
する。The length of the masking material 10 in the casting direction is
It is desirable that the length of the magnetic pole 8 be equal to or greater than the length in the casting direction. When the casting width is changed, the masking material 10 moves in synchronization with the short side 3 of the mold, or the arrangement position of the masking material 10 is changed every time the slab width is changed, so that the installation position always falls within the above range. Be satisfied.

【００２８】マスキング材１０の材質は、純鉄、磁性
鋼、珪素鋼、Ｎｉを３０〜８０ｗｔ％含有したパー
マロイと呼ばれるＦｅ−Ｎｉ合金、フェライトと呼ば
れＦｅ₂ Ｏ₃ を主成分とする酸化物、非晶質金属等の
軟質磁性材料から適宜選択する。The material of the masking material 10 is pure iron, magnetic steel, silicon steel, a Fe-Ni alloy called Permalloy containing 30 to 80 wt% of Ni, an oxide called ferrite and containing Fe ₂ O ₃ as a main component. And a soft magnetic material such as an amorphous metal.

【００２９】印加する交流電源の周波数は、１Ｈｚから
６０Ｈｚの範囲が望ましい。１Ｈｚ未満の場合は、磁気
制動力が作用しない磁束密度の零になる時間が長くなる
ので、溶鋼流の慣性力のため磁束密度が零になる時間に
通過した溶鋼が間欠流となり鋳型内溶鋼の表面流を乱し
て表面流が不均一になるため、添加したモールドパウダ
ーの巻き込みの虞があるためである。又、交流磁界では
周波数の増大と共にインピーダンスが上昇するので、６
０Ｈｚ以上の周波数で磁束密度を確保するには、大電圧
を発生する巨大な電源装置が必要となり効率的でないた
めである。The frequency of the AC power supply to be applied is preferably in the range of 1 Hz to 60 Hz. If the frequency is less than 1 Hz, the time during which the magnetic flux density at which the magnetic braking force does not act becomes zero becomes longer, so that the molten steel passing at the time when the magnetic flux density becomes zero due to the inertia force of the molten steel flow becomes an intermittent flow, and This is because the surface flow is disturbed and the surface flow becomes non-uniform, so that the added mold powder may be involved. In an AC magnetic field, the impedance rises with an increase in frequency.
This is because securing a magnetic flux density at a frequency of 0 Hz or more requires a huge power supply device that generates a large voltage and is inefficient.

【００３０】このようにしてマスキング材１０を配置
し、磁界静止型交流磁界から磁界を印加して、本発明に
よる鋳型内溶鋼の流動制御を実施する。The masking material 10 is arranged as described above, and a magnetic field is applied from a static magnetic field alternating current magnetic field to control the flow of the molten steel in the mold according to the present invention.

【００３１】尚、図１は磁極８、８が鋳型１の側部を通
るリターンヨーク１２で繋がり、鋳型長辺２の背面には
同一極性の磁極が配置された構成であるが、本発明の適
用はこの構成に限るものではなく、例えば、鋳型長辺２
の背面に浸漬ノズル４を中心として左右２つに分割され
リターンヨークで繋がった磁極を配置し、更に対向する
鋳型長辺２の背面に同一な磁極を配置し、対向する磁極
が異極となるように交流電源を印加して磁界静止型交流
磁界を形成する構成でも本発明の適用は可能である。FIG. 1 shows a configuration in which the magnetic poles 8, 8 are connected by a return yoke 12 passing through the side of the mold 1 and magnetic poles of the same polarity are arranged on the back of the long side 2 of the mold. The application is not limited to this configuration.
A magnetic pole divided into two parts, left and right, centered on the immersion nozzle 4 and connected by a return yoke, is arranged on the back side of the mold, and the same magnetic pole is arranged on the back side of the opposite long side 2 of the mold. The present invention is also applicable to a configuration in which a static magnetic field is formed by applying an AC power supply.

【００３２】[0032]

【実施例】自動車外装用鋼板として表面の清浄性が要求
される炭素濃度が０．００３ｗｔ％のＡｌキルド鋼を対
象に、図１に示した磁界静止型交流磁界及びマスキング
材の配置にて、鋳片断面が矩形型の連続鋳造機におい
て、鋳片幅１２００ｍｍ、鋳片厚み２５０ｍｍ、鋳片引
抜き速度２．０ｍ／ｍｉｎ、交流電源の周波数１Ｈｚの
条件で本発明を実施した。鋳型長さは９５０ｍｍで、溶
鋼量は２５０ｔｏｎ／ヒートである。EXAMPLE An Al-killed steel sheet having a carbon concentration of 0.003 wt%, which requires surface cleanliness as a steel sheet for automobile exteriors, was subjected to a static magnetic field alternating magnetic field and a masking material arrangement shown in FIG. The present invention was carried out in a continuous casting machine having a rectangular slab section with a slab width of 1200 mm, a slab thickness of 250 mm, a slab drawing speed of 2.0 m / min, and an AC power supply frequency of 1 Hz. The mold length is 950 mm and the amount of molten steel is 250 ton / heat.

【００３３】磁極の鋳造方向長さは４５０ｍｍで、磁極
の鋳造方向中心位置を浸漬ノズル吐出孔下端から１５０
ｍｍとした。マスキング材は、厚み１．０ｍｍ、鋳造方
向長さ５００ｍｍ、珪素濃度１．０ｗｔ％の珪素鋼板を
用い、対向するマスキング材との間隔距離（Ｌ）を３５
０ｍｍとして配置した。The length of the magnetic pole in the casting direction is 450 mm, and the center position of the magnetic pole in the casting direction is 150 mm from the lower end of the immersion nozzle discharge hole.
mm. As the masking material, a silicon steel sheet having a thickness of 1.0 mm, a length in the casting direction of 500 mm, and a silicon concentration of 1.0 wt% is used, and the distance (L) between the opposing masking materials is set to 35.
It was arranged as 0 mm.

【００３４】鋳型長辺を挟んで対向するマスキング材の
連結材として、厚み１．０ｍｍ、鋳造方向長さ３００ｍ
ｍ、珪素濃度１．０ｗｔ％の珪素鋼板を用い、マスキン
グ材とビス止めした。As a connecting material of the masking material facing the mold with the long side interposed therebetween, a thickness of 1.0 mm and a length of 300 m in the casting direction are used.
m, a silicon steel sheet having a silicon concentration of 1.0 wt% was screwed with a masking material.

【００３５】そして、鋳片幅中央部の鋳片厚み中心位置
における最大磁束密度が１５００ガウスとなるように交
流電源を印加して鋳造を実施した。尚、比較のために、
マスキング材を配置せず、その他の条件は実施例と同一
の条件で鋳造を実施した。Then, casting was performed by applying an AC power supply such that the maximum magnetic flux density at the center of the slab thickness at the center of the slab width was 1500 gauss. For comparison,
The casting was carried out under the same conditions as in the example except that no masking material was arranged.

【００３６】そして、このようにして鋳造された各５ヒ
ートの鋳片を熱間圧延及び冷間圧延して薄鋼板にまで圧
延し、薄鋼板において非金属介在物による表面欠陥の品
質調査を行った。Then, the slab of each of the five heats thus cast is hot-rolled and cold-rolled to be rolled into a thin steel sheet, and the quality of surface defects caused by nonmetallic inclusions in the thin steel sheet is examined. Was.

【００３７】図３は鋳型内の鋳片厚みの中央位置におけ
る鋳片幅方向の磁束密度の分布をマスキング材の有無に
より調査した結果である。鋳片短辺部分での磁束密度
は、マスキング材を配置しない場合には鋳片中央部の約
１／２程度まで減少するのに対し、マスキング材を配置
することで減少分を抑え、逆に鋳片中央部より磁束密度
を高めることができた。FIG. 3 shows the result of investigation of the distribution of magnetic flux density in the slab width direction at the center position of the slab thickness in the mold depending on the presence or absence of a masking material. The magnetic flux density at the short side of the slab decreases to about 1/2 of the central part of the slab when no masking material is arranged, whereas the decrease is suppressed by arranging the masking material. The magnetic flux density was higher than that of the slab center.

【００３８】図４は本発明による実施例と比較例とで薄
鋼板における表面品質の調査結果を示したもので、縦軸
の品質欠陥インデックスは数値が大きい程品質が良いこ
とを示している。本発明の実施例では、鋳片中央側及び
鋳片短辺側とも良好な成績であるのに対して、比較例で
は鋳片中央側及び鋳片短辺側とも品質欠陥があり、特に
鋳片短辺側の欠陥が多い。FIG. 4 shows the results of an examination of the surface quality of a thin steel sheet in Examples and Comparative Examples according to the present invention. The larger the numerical value of the quality defect index on the vertical axis, the better the quality. In the examples of the present invention, while the slab center side and the slab short side side have good results, the comparative example has quality defects on both the slab center side and the slab short side side, especially the slab Many defects on the short side.

【００３９】以上のように、本発明を適用することで鋳
片幅方向全体にわたって清浄な鋳片を得ることができ
た。As described above, by applying the present invention, a clean slab could be obtained over the entire slab width direction.

【００４０】[0040]

【発明の効果】本発明によれば、鋳片短辺近傍の磁束密
度を高め、磁気による溶鋼の制動力を鋳片幅方向で均一
化でき、浸漬ノズルからの吐出流を制動可能となるの
で、脱酸生成物及びモールドパウダーによる非金属介在
物の極めて少ない清浄な鋳片を得ることができる。According to the present invention, the magnetic flux density in the vicinity of the short side of the slab is increased, the braking force of the molten steel by magnetism can be made uniform in the slab width direction, and the discharge flow from the immersion nozzle can be braked. In addition, it is possible to obtain a clean slab with extremely little nonmetallic inclusions due to deoxidation products and mold powder.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明を適用した鋳片断面が矩形型の連続鋳造
機鋳型部分の概要を示したもので、（ａ）は側面からみ
た概要図、（ｂ）は平面からみた概要図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an outline of a mold part of a continuous casting machine having a rectangular cast slab to which the present invention is applied, (a) is a schematic diagram viewed from a side, and (b) is a schematic diagram viewed from a plane. .

【図２】磁界により鋳型中に生起した誘導電流の流れる
様子の例を模式的に示した図で、（ａ）はマスキング材
の無い場合を、（ｂ）はマスキング材を設置した場合で
ある。FIGS. 2A and 2B are diagrams schematically showing an example of a state in which an induced current generated in a mold by a magnetic field flows. FIG. 2A shows a case without a masking material, and FIG. 2B shows a case with a masking material installed. .

【図３】鋳型内の鋳片厚みの中央位置における鋳片幅方
向の磁束密度の分布を本発明の実施例と比較例とで比較
して示した図である。FIG. 3 is a diagram showing a distribution of a magnetic flux density in a slab width direction at a center position of a slab thickness in a mold in comparison between an example of the present invention and a comparative example.

【図４】本発明による実施例と比較例とで薄鋼板におけ
る非金属介在物による表面欠陥の調査結果を比較して示
した図である。FIG. 4 is a diagram showing a comparison between the results of an examination of surface defects caused by nonmetallic inclusions in a thin steel sheet in an example according to the present invention and a comparative example.

【符号の説明】[Explanation of symbols]

１；鋳型 ２；鋳型長辺 ３；鋳型短辺 ４；浸漬ノズル ５；吐出孔 ６；溶鋼 ７；鋳片 ８；磁極 ９；コイル １０；マスキング材 １１；連結材 １２；リターンヨーク DESCRIPTION OF SYMBOLS 1; Mold 2; Mold long side 3; Mold short side 4; Immersion nozzle 5; Discharge hole 6; Molten steel 7; Cast piece 8; Magnetic pole 9; Coil 10; Masking material 11;

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 交流電源を印加して、対向する鋳型長辺
の各背面に鋳片幅方向全体にわたって配置された磁極間
に異極が対向する磁界静止型交流磁界を発生させ、この
磁界静止型交流磁界により浸漬ノズルから鋳型内に注入
される溶鋼吐出流を制動する鋳型内溶鋼の流動制御方法
において、 軟質磁性材料からなるマスキング材を、鋳型長辺と磁極
との間に鋳型短辺近傍位置から鋳型幅方向外側の全幅に
わたって鋳型長辺を挟んで対向し、且つ対向するマスキ
ング材を軟質磁性材料にて連結して設置し、磁束密度を
鋳片短辺部分に集中させることを特徴とする連続鋳造鋳
型内溶鋼の流動制御方法。An alternating current power source is applied to generate a magnetic field static type alternating magnetic field in which different poles face each other between magnetic poles arranged over the entire width direction of a slab on each back surface of a long side of a facing mold. A method for controlling the flow of molten steel in a mold, which damps a discharge flow of molten steel injected into the mold from an immersion nozzle by a mold alternating magnetic field, comprising the steps of: placing a masking material made of a soft magnetic material near a short side of the mold between a long side of the mold and a magnetic pole; It is characterized by opposing the long side of the mold across the entire width in the width direction of the mold from the position and connecting the facing masking material with a soft magnetic material and installing it, and concentrating the magnetic flux density on the short side of the slab. To control the flow of molten steel in a continuous casting mold.