JP2007069236A - Method for continuously casting molten metal - Google Patents

Method for continuously casting molten metal Download PDF

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JP2007069236A
JP2007069236A JP2005258647A JP2005258647A JP2007069236A JP 2007069236 A JP2007069236 A JP 2007069236A JP 2005258647 A JP2005258647 A JP 2005258647A JP 2005258647 A JP2005258647 A JP 2005258647A JP 2007069236 A JP2007069236 A JP 2007069236A
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molten metal
tundish
refractory structure
immersion nozzle
nozzle
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JP4419934B2 (en
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Yuichi Tsukaguchi
友一 塚口
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Nippon Steel Corp
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Sumitomo Metal Industries Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous casting method with which fluidity of molten metal in a mold can be stabilized without clogging an immersion nozzle by arranging a swirling flow giving mechanism in a tundish. <P>SOLUTION: In the continuous casting method, a hollow cylindrical state circular cone- or truncated cone-shaped refractory-made structural body having side holes at the side wall, in which the side hole has the center of an outlet opening hole part of the side hole at the crossing point of a virtual line radially extended from the center of a horizontal directional cross section in this structural body and the inner surface of the structural body and has an inclined angle with respect to the virtual line at the outlet side opening hole part, is disposed into the tundish at the upper part of the immersion nozzle under perpendicular state of this axis, and the swirling flow is given to the molten metal to be supplied into the immersion nozzle by passing through the molten metal from the inlet side opening part of the side hole of the outer surface of this structural body toward an outlet side opening part on the inner surface of this structural body. It is desirable that the maximum inner diameter in the circular cross section is 150 to 3,000mm and the height of the inner surface is 50-2,000mm, and the inclined angle of the side hole in the outlet side opening part is 15-80°. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、溶鋼などの溶融金属の連続鋳造に用いる浸漬ノズル内を通過する溶融金属に旋回流を付与して、ノズル詰まりを防止し、鋳型内における溶融金属の流動を安定化する技術に関する。   The present invention relates to a technique for preventing swirling of a molten metal passing through an immersion nozzle used for continuous casting of molten metal such as molten steel to prevent nozzle clogging and stabilizing the flow of molten metal in a mold.

スラブの連続鋳造のように幅の広い鋳型内に、対向する吐出孔を有する一本の浸漬ノズルを浸漬して溶融金属を供給する連続鋳造においては、鋳型内の流動が自励振動を起こし、流速の変動や湯面の波立ちが発生しやすい。その結果、鋳片表層部の品質に異常が発生し、鋳造速度の低下を余儀なくされることがある。   In continuous casting where a molten metal is supplied by immersing a single immersion nozzle having opposing discharge holes in a wide mold like a continuous casting of a slab, the flow in the mold causes self-excited vibration, Fluctuations in flow velocity and ripples on the surface of the water are likely to occur. As a result, abnormalities occur in the quality of the slab surface layer, and the casting speed may be reduced.

従来より、この鋳型内流動を制御することを目的として、電磁気力を用いた電磁ブレーキや電磁撹拌、または特許文献１や特許文献２などに開示されているような旋回流を付与する浸漬ノズルが公知である。すなわち、上記特許文献１には、浸漬ノズル内の溶鋼流に旋回を付与するためのねじりテープ状の部品を備えてなる浸漬ノズルが記載されている。また、特許文献２には、内部にねじり板型旋回羽根を設置した浸漬ノズルであって、旋回羽根捩りピッチ、旋回羽根捩り角、旋回羽根の外径、旋回羽根の厚みを所定範囲内の値とし、旋回羽根下端と吐出孔との間において内径を絞り、絞り後の横断面を規定するとともに、タンディッシュと鋳型間の必要ヘッド予測値を適正範囲内におさめた連続鋳造用浸漬ノズルが記載されている。   Conventionally, for the purpose of controlling the flow in the mold, an electromagnetic brake or electromagnetic stirring using electromagnetic force, or an immersion nozzle that imparts a swirling flow as disclosed in Patent Document 1 or Patent Document 2 has been provided. It is known. That is, Patent Document 1 describes an immersion nozzle including a twisted tape-shaped component for imparting swirl to a molten steel flow in the immersion nozzle. Patent Document 2 discloses an immersion nozzle having a torsion plate-type swirl blade installed therein, and values of swirl blade twist pitch, swirl blade twist angle, swirl blade outer diameter, swirl blade thickness within a predetermined range. Describes a continuous casting immersion nozzle that squeezes the inner diameter between the lower end of the swirl vane and the discharge hole, defines the cross section after squeezing, and keeps the required head predicted value between the tundish and the mold within the appropriate range Has been.

さらに、特許文献３に開示されたようにノズル底部の滝壺状凹みの深さを大きくした浸漬ノズル、または特許文献４に開示されたようにノズル内径に段差を設けた浸漬ノズルが
公知である。上記特許文献３には、鋳片短辺壁の内側に位置するノズル本体とノズル本体の側壁に形成し且つ鋳片短辺壁に向けて下向きに開口した吐出孔と、ノズル本体の底部凹状のボックスとを有する連続鋳造用ノズルにおいて、ボックスの深さと内径との比、および吐出孔の吐出角度を規定した連続鋳造用浸漬ノズルが開示されている。そして、特許文献４には、溶鋼と接する部分を構成する耐火材料が黒鉛を含有してなり、ノズル内孔部に、段差構造部位が長さを有する段差構造を複数有する連続鋳造用浸漬ノズルにおいて、溶鋼通過量に対してノズル内孔部の最小内径、最小横断面積、吐出孔の断面積を規定した浸漬ノズルが開示されている。 Furthermore, an immersion nozzle in which the depth of the waterfall-shaped dent at the bottom of the nozzle is increased as disclosed in Patent Document 3, or an immersion nozzle having a step on the nozzle inner diameter as disclosed in Patent Document 4 is known. . In the above-mentioned Patent Document 3, a nozzle main body positioned inside the slab short side wall, a discharge hole formed in the side wall of the nozzle main body and opened downward toward the slab short side wall, and a bottom concave shape of the nozzle main body are formed. In a continuous casting nozzle having a box, a continuous casting immersion nozzle is disclosed in which the ratio between the depth and inner diameter of the box and the discharge angle of the discharge holes are defined. And in patent document 4, the refractory material which comprises the part which contact | connects molten steel contains graphite, In the nozzle for continuous casting which has a plurality of level | step difference structures in which the level | step difference structure site | part has length in a nozzle inner hole part An immersion nozzle is disclosed in which the minimum inner diameter, the minimum cross-sectional area, and the cross-sectional area of the discharge hole are defined with respect to the passing amount of molten steel.

しかしながら、電磁気力を用いる方法は、設備コストが高く、投資に見合ったメリットが得られないことが多い。また、制御対象である溶融金属流を計測することが難しいので制御対象の状態が不明確なまま制御を行うことが多く、技術的にも十分な効果を発揮させることは難しい。   However, the method using the electromagnetic force has a high equipment cost and often cannot obtain a merit corresponding to the investment. In addition, since it is difficult to measure the molten metal flow that is a control target, control is often performed while the state of the control target is unclear, and it is difficult to achieve a sufficient technical effect.

一方、前記特許文献１または２に開示された旋回流を付与する浸漬ノズル（以下、「旋回流付与浸漬ノズル」とも記す）に関する技術は、鋳型内流動を安定化することができる現実的対策としてその有効性が確認されているが、非金属介在物を多く含む清浄度の低い溶融金属を鋳造すると、ノズル内に設ける旋回羽根に非金属介在物が付着しやすく、多量の溶融金属を連続して鋳造することは難しいという問題がある。   On the other hand, the technique relating to the immersion nozzle for imparting the swirl flow disclosed in Patent Document 1 or 2 (hereinafter also referred to as “swirl flow imparting immersion nozzle”) is a practical measure that can stabilize the flow in the mold. Although its effectiveness has been confirmed, when casting a low-cleanness molten metal containing a large amount of non-metallic inclusions, non-metallic inclusions tend to adhere to the swirl blades provided in the nozzle, and a large amount of molten metal is continuously added. There is a problem that it is difficult to cast.

また、特許文献３に開示された浸漬ノズルを用いれば、鋳造速度を増加させても鋳型内の表面流速は増加することがなく、モールドパウダーの巻き込みを有効に防止することができるとされているが、実操業においては安定した巻き込み防止効果は得られにくい。さらに、特許文献４に開示された浸漬ノズルは、アルミナ付着による浸漬ノズルの閉塞を防止するとともに、浸漬ノズル内の溶鋼の偏流を抑制することにより鋳型内の流動を均一化し、鋳片品質の向上およびブレークアウトの発生防止を狙ったものである。しかしながら、このようなノズルを用いても、現実の鋳造操業においてはノズル詰まりが発生しやすく、また、安定した偏流抑制効果も得られにくい。   Further, if the immersion nozzle disclosed in Patent Document 3 is used, the surface flow velocity in the mold does not increase even if the casting speed is increased, and it is said that the entrainment of mold powder can be effectively prevented. However, it is difficult to obtain a stable entrainment preventing effect in actual operation. Furthermore, the immersion nozzle disclosed in Patent Document 4 prevents clogging of the immersion nozzle due to alumina adhesion, and suppresses the drift of molten steel in the immersion nozzle, thereby making the flow in the mold uniform and improving the quality of the slab. It aims to prevent breakouts. However, even if such a nozzle is used, nozzle clogging is likely to occur in an actual casting operation, and it is difficult to obtain a stable drift suppression effect.

ＷＯ９９／１５２９１号公報（特許請求の範囲および５頁１０行〜６頁８行）WO99 / 15291 (Claims and 5 pages 10 lines to 6 pages 8 lines) 特開２００２−２３９６９０号公報（特許請求の範囲および段落［００１０］〜［００１３］）JP 2002-239690 A (Claims and paragraphs [0010] to [0013]) 特許第３０２７６４５号公報（特許請求の範囲および段落［０００５］）Japanese Patent No. 3027645 (Claims and paragraph [0005]) 特許第３２０７７９３号公報（特許請求の範囲および段落［００１５］および［００１６］）Japanese Patent No. 3207793 (Claims and paragraphs [0015] and [0016])

本発明は、上記の問題に鑑みてなされたものであり、その課題は、タンディッシュ内に溶融金属の旋回流を形成させる簡便で効果的な旋回流付与機構を設けることにより、前記旋回羽根を有する旋回流付与浸漬ノズルの欠点であるノズル詰まりを解消して、鋳型内における溶融金属の流動を安定化し、安定した鋳造操業および鋳片の品質向上を達成できる連続鋳造方法を提供することにある。   The present invention has been made in view of the above problems, and the problem is that the swirl vane is provided by providing a simple and effective swirl flow imparting mechanism for forming a swirl flow of molten metal in the tundish. It is to provide a continuous casting method that eliminates nozzle clogging, which is a drawback of a swirling flow imparting immersion nozzle, stabilizes the flow of molten metal in the mold, and achieves stable casting operation and improved quality of the slab. .

本発明者は、上述の課題を解決するために、従来の問題点を踏まえて、浸漬ノズルにおけるノズル詰まりを起こすことなく、浸漬ノズルを通過する溶融金属流に旋回流を付与し、鋳型内における溶融金属の流動を安定化することのできる鋳造方法について検討および考察を重ねた結果、下記の（ａ）〜（ｃ）の知見を得て、本発明を完成させた。   In order to solve the above-mentioned problems, the present inventor gives a swirl flow to the molten metal flow passing through the immersion nozzle without causing nozzle clogging in the immersion nozzle based on the conventional problems, As a result of repeated examination and consideration of a casting method capable of stabilizing the flow of molten metal, the following knowledge (a) to (c) was obtained and the present invention was completed.

（ａ）浸漬ノズル内にねじり板状の旋回羽根を設置して旋回流を形成する方法は、浸漬ノズル内の溶融金属下降流が旋回羽根に当たる際に流れの淀みや渦を生じ、Ａｌ2Ｏ3などの非金属介在物の付着を招く。また、流速の大きな浸漬ノズル内にねじり板状旋回羽根のような旋回流付与機構を設置すると、溶融金属の摩擦抵抗が増大し、タンディッシュヘッドの大きな連続鋳造機を用いなければスループットが制限され、さらに、必要なスループットを得るためには旋回速度を弱めざるを得なくなるなど、エネルギの有効利用の面でも好ましくない。 (A) a method of forming a twist-shaped swirl vanes in the immersion nozzle installed swirl flow results in stagnation and eddy flow in the molten metal downward flow in the immersion nozzle strikes the swirl vane, Al 2 O Non-metallic inclusions such as 3 are attached. If a swirl flow imparting mechanism such as a twisted plate swirl blade is installed in a submerged nozzle with a high flow rate, the frictional resistance of the molten metal increases, and throughput is limited unless a continuous casting machine with a large tundish head is used. Furthermore, in order to obtain the required throughput, it is not preferable in terms of effective use of energy, for example, the turning speed must be reduced.

（ｂ）浸漬ノズル上方のタンディッシュ内に、直径の比較的大きな中空の円筒状、円錐状または円錐台状の側面を有し、その側面に、溶融金属が円周方向の速度成分を付与されながら中空内部に流入できる側孔を設けた旋回流付与機構を設置することにより、旋回流付与機構における溶融金属通路の断面積を大きく確保することができ、溶融金属の流速が小さい条件において旋回流を付与することができる。   (B) The tundish above the immersion nozzle has a hollow cylindrical, conical or frustoconical side surface with a relatively large diameter, and the molten metal is given a circumferential velocity component on the side surface. However, by installing a swirling flow imparting mechanism with side holes that can flow into the hollow interior, a large cross-sectional area of the molten metal passage in the swirling flow imparting mechanism can be secured, and swirling flow is performed under conditions where the molten metal flow rate is low. Can be granted.

（ｃ）上記（ｂ）の構成とすることにより、Ａｌ2Ｏ3などの非金属介在物が旋回流付与機構に付着しにくくなり、また、たとえ付着したとしても、旋回流付与機構の閉塞には至りにくくなる。さらに、溶融金属の摩擦抵抗を小さくできるので、タンディッシュヘッドを有効に活用でき、強い旋回流を得ることができる。 (C) With the configuration of (b) above, non-metallic inclusions such as Al 2 O 3 are less likely to adhere to the swirl flow imparting mechanism, and even if they adhere, the swirl flow imparting mechanism is blocked. Is difficult to reach. Furthermore, since the frictional resistance of the molten metal can be reduced, the tundish head can be used effectively and a strong swirling flow can be obtained.

本発明は、上記の知見に基づいて完成されたものであり、その要旨は、下記の（１）〜（４）に示す溶融金属の連続鋳造方法にある。   This invention is completed based on said knowledge, The summary exists in the continuous casting method of the molten metal shown to following (1)-(4).

（１）側壁に１つ以上の側孔が設けられた中空の円筒状、円錐状または円錐台状の耐火物製構造体であり、該側孔は該耐火物製構造体の水平方向の円形断面の中心から放射状に伸びる仮想線と該耐火物構造体の内面との交点に側孔の出側開口部の中心を有し、該出側開口部において該仮想線に対して側孔の中心軸を傾斜させて設けられた耐火物製構造体を、該耐火物製構造体の軸を鉛直にして、浸漬ノズル上方のタンディッシュ内に配置し、該タンディッシュ内の溶融金属を、耐火物製構造体外面に開口した側孔の入側開口部から耐火物製構造体内面に開口した出側開口部に向かって通過させることにより、該タンディッシュから浸漬ノズル内に供給される溶融金属に旋回流を付与して鋳造する溶融金属の連続鋳造方法（以下、「第１発明」とも記す）。   (1) A hollow cylindrical, conical or frustoconical refractory structure provided with one or more side holes on the side wall, the side holes being circular in the horizontal direction of the refractory structure A center of the side hole with respect to the imaginary line in the outlet side opening at the intersection of the virtual line extending radially from the center of the cross section and the inner surface of the refractory structure A refractory structure provided with an inclined axis is placed in a tundish above the immersion nozzle with the axis of the refractory structure vertical, and the molten metal in the tundish is refractory. The molten metal supplied into the immersion nozzle from the tundish is allowed to pass from the entrance side opening of the side hole opened to the outer surface of the structure to the exit side opening opened to the inner surface of the refractory structure. Method for continuous casting of molten metal cast by applying a swirl flow (hereinafter referred to as “first invention”) Also referred to).

（２）前記水平方向の円形断面における最大内径が１５０ｍｍ〜３０００ｍｍ、内面の高さが５０ｍｍ〜２０００ｍｍであり、前記出側開口部において仮想線に対して側孔の中心軸のなす角度が１５°〜８０°である耐火物製構造体をタンディッシュ内に配置して鋳造する前記（１）に記載の溶融金属の連続鋳造方法（以下、「第２発明」とも記す）。   (2) The maximum inner diameter in the horizontal circular cross section is 150 mm to 3000 mm, the inner surface height is 50 mm to 2000 mm, and the angle formed by the central axis of the side hole with respect to the imaginary line in the outlet opening is 15 °. The molten metal continuous casting method according to (1) above, in which a refractory structure of -80 ° is placed and cast in a tundish (hereinafter also referred to as “second invention”).

（３）前記耐火物製構造体の上端部に開孔部が設けられ、該開孔部を通してタンディッシュの上部から底部まで耐火物製ストッパーロッドが配置された耐火物製構造体を用いて鋳造する前記（１）または（２）に記載の溶融金属の連続鋳造方法（以下、「第３発明」とも記す）。   (3) Casting is performed using a refractory structure in which an opening is provided at the upper end of the refractory structure, and a refractory stopper rod is disposed from the top to the bottom of the tundish through the opening. The molten metal continuous casting method according to (1) or (2) above (hereinafter also referred to as “third invention”).

（４）前記タンディッシュに配置された上ノズル、スライディングゲートおよび浸漬ノズルのうちの少なくとも１つにおいて、溶鋼と接するその内壁面から、溶鋼中に不活性ガスを吹き込む前記（１）〜（３）のいずれかに記載の溶融金属の連続鋳造方法（以下、「第４発明」とも記す）。   (4) In at least one of the upper nozzle, sliding gate and immersion nozzle arranged in the tundish, the inert gas is blown into the molten steel from the inner wall surface in contact with the molten steel (1) to (3) Or a molten metal continuous casting method according to any one of the above (hereinafter also referred to as "fourth invention").

本発明において、「円形断面における最大内径」とは、耐火物製構造体の水平方向断面の内径の最大値を意味し、内径が構造体の軸方向で変化する場合には、その最大値を意味する。   In the present invention, the “maximum inner diameter in a circular cross section” means the maximum value of the inner diameter of the horizontal section of the refractory structure, and when the inner diameter changes in the axial direction of the structure, the maximum value is means.

また、「出側開口部において仮想線に対して側孔の中心軸のなす角度」を以下の説明においては、「側孔の傾斜角度（θ１）」とも記す。   Further, “the angle formed by the central axis of the side hole with respect to the imaginary line in the exit side opening” is also referred to as “the inclination angle (θ1) of the side hole” in the following description.

本発明の方法によれば、旋回羽根を有する旋回流付与浸漬ノズルの欠点であるノズル閉塞を起こすことなく、浸漬ノズル内の溶融金属に旋回流を形成させ、旋回流付与浸漬ノズルが有する、鋳型内溶融金属の優れた流動安定性や、非金属介在物の除去などの効果を享受して、安定した連続鋳造操業および鋳片の品質向上を達成することができる。   According to the method of the present invention, without causing the nozzle clogging which is a defect of the swirl flow imparting immersion nozzle having swirl vanes, the swirl flow is formed in the molten metal in the immersion nozzle, and the mold which the swirl flow imparting immersion nozzle has By taking advantage of the excellent flow stability of the inner molten metal and the removal of non-metallic inclusions, it is possible to achieve stable continuous casting operations and improved slab quality.

前述のとおり、本発明は、「側壁に１つ以上の側孔が設けられた中空の円筒状、円錐状または円錐台状の耐火物製構造体であり、側孔は耐火物製構造体の水平方向の円形断面の中心から放射状に伸びる仮想線と耐火物構造体の内面との交点に側孔の出側開口部の中心を有し、出側開口部において仮想線に対して側孔の中心軸を傾斜させて設けられた耐火物製構造体を、耐火物製構造体の軸を鉛直にして、浸漬ノズル上方のタンディッシュ内に配置し、タンディッシュ内の溶融金属を、該構造体外面に開口した側孔の入側開口部から該構造体内面に開口した出側開口部に向かって通過させることにより、タンディッシュから浸漬ノズル内に供給される溶融金属に旋回流を付与する溶融金属の連続鋳造方法」である。本発明の内容について、下記にさらに詳細に説明する。   As described above, the present invention is “a hollow cylindrical, conical or truncated cone refractory structure with one or more side holes provided on the side walls, and the side holes are refractory structures. It has the center of the exit opening of the side hole at the intersection of the virtual line radially extending from the center of the horizontal circular section and the inner surface of the refractory structure, A refractory structure provided with an inclined central axis is placed in the tundish above the immersion nozzle with the axis of the refractory structure vertical, and the molten metal in the tundish is placed in the structure. Melting that imparts a swirling flow to the molten metal supplied from the tundish into the immersion nozzle by passing from the entrance side opening of the side hole that opens to the outer surface toward the exit side opening that opens to the inner surface of the structure. "Metal continuous casting method". The contents of the present invention will be described in more detail below.

図１は、本発明の方法を実施するための連続鋳造装置を模式的に示す図であり、同図（ａ）は、同図（ｂ）におけるＡ−Ａ断面図を表し、同図（ｂ）は連続鋳造装置の縦断面図を表す。   FIG. 1 is a diagram schematically showing a continuous casting apparatus for carrying out the method of the present invention. FIG. 1 (a) is a cross-sectional view taken along line AA in FIG. 1 (b), and FIG. ) Represents a longitudinal sectional view of the continuous casting apparatus.

同図に示されるとおり、浸漬ノズル４上方のタンディッシュ５内に、水平方向の円形断面の中心Ｏから放射状に伸びる仮想線Ｘ１〜Ｘ５上に孔出口の中心を有し、仮想線Ｘ１〜Ｘ５に対して孔の中心軸の方向Ｙ１〜Ｙ５を傾斜させて開口した側孔２が、その側壁に１つ以上設けられた中空の筒状の耐火物製構造体１が、その耐火物製構造体の軸３を鉛直にして、配置されている。タンディッシュ５内の溶融金属６は、側孔２を通過して耐火物製構造体１内に流入する際に、円周方向の速度成分を付与されて旋回流を形成し、タンディッシュ５から浸漬ノズル４内を経て鋳型１１に供給される。   As shown in the figure, in the tundish 5 above the submerged nozzle 4, the center of the hole outlet is located on virtual lines X1 to X5 extending radially from the center O of the horizontal circular section, and the virtual lines X1 to X5 The hollow cylindrical refractory structure 1 in which one or more side holes 2 opened by inclining the directions Y1 to Y5 of the central axis of the hole are provided on the side wall thereof is the refractory structure. It is arranged with the body axis 3 vertical. When the molten metal 6 in the tundish 5 passes through the side holes 2 and flows into the refractory structure 1, a circumferential velocity component is applied to form a swirling flow. It is supplied to the mold 11 through the immersion nozzle 4.

（１）第１発明
前記のとおり、第１発明は、水平方向の円形断面の中心Ｏから放射状に伸びる仮想線Ｘ１〜ＸＮ（ただし、Ｎは仮想線の数を表す）上に孔の出側開口部中心を有し、仮想線Ｘ１〜ＸＮに対して孔の中心軸の方向を傾斜角度θ１だけ傾斜させて穿たれた側孔２が、その側壁に１つ以上設けられた中空の円筒状、円錐状または円錐台状の耐火物製構造体１を、耐火物製構造体１の軸３を鉛直にして、浸漬ノズル４上方のタンディッシュ５内に配置し、タンディッシュ５内の溶融金属６を耐火物製構造体１の外面に開口した側孔２の入側開口部から耐火物製構造体１内面に開口した出側開口部に向かって通過させることにより、該タンディッシュ５から浸漬ノズル４内に供給される溶融金属に旋回流を付与して鋳造する溶融金属の連続鋳造方法である。 (1) 1st invention As above-mentioned, 1st invention is the outgoing side of a hole on the virtual lines X1-XN (however, N represents the number of virtual lines) radially extended from the center O of a horizontal circular cross section. A hollow cylindrical shape having one or more side holes 2 having a center of the opening and formed by tilting the direction of the center axis of the hole with respect to the imaginary lines X1 to XN by an inclination angle θ1. The refractory structure 1 having a conical or frustoconical shape is placed in the tundish 5 above the immersion nozzle 4 with the axis 3 of the refractory structure 1 vertical, and the molten metal in the tundish 5 6 is passed from the entrance opening of the side hole 2 opened to the outer surface of the refractory structure 1 toward the exit opening opened to the inner surface of the refractory structure 1, so that it is immersed in the tundish 5. A series of molten metals cast by applying a swirling flow to the molten metal supplied into the nozzle 4 A casting method.

この耐火物製構造体１は、傾斜角度θ１を有する側孔２を備えていることにより、溶融金属６に円周方向の流速成分を付与し、旋回流を形成させることができる。傾斜角度θ１を有する側孔２は、１個であってもよいが、溶融金属６による閉塞を防止する観点から、耐火物製構造体１の全周に複数個あることが好ましい。また、側孔２は耐火物製構造体１の全周に複数個、かつ構造体の高さ方向（軸方向）に複数段設けてもよい。複数個設ける側孔２の傾斜角度θ１は同一であっても、また、ある範囲内で変動があってもよいが、溶融金属６に付与する旋回流の回転方向が同一であることが好ましい。さらに、側孔２の隔壁が薄いフィン状であり耐火物製構造体１の円周方向に多数の側孔を有する形状であってもよい。   Since the refractory structure 1 includes the side holes 2 having the inclination angle θ1, a circumferential flow velocity component can be imparted to the molten metal 6 to form a swirling flow. Although the number of the side holes 2 having the inclination angle θ1 may be one, it is preferable that there are a plurality of side holes 2 on the entire circumference of the refractory structure 1 from the viewpoint of preventing the molten metal 6 from blocking. Further, a plurality of side holes 2 may be provided on the entire circumference of the refractory structure 1 and a plurality of stages in the height direction (axial direction) of the structure. The plurality of side holes 2 may have the same inclination angle θ1 or may vary within a certain range, but the rotational direction of the swirl flow applied to the molten metal 6 is preferably the same. Furthermore, the partition of the side hole 2 may be a thin fin shape and may have a shape having a large number of side holes in the circumferential direction of the refractory structure 1.

側孔２の大きさは、溶融金属中の最大粒径が５０ｍｍ程度の異物でも通過できる断面積を有することが好ましい。側孔２の上側および下側の内壁面は、水平であっても傾斜していても構わないが、側孔２の高さ位置は、鋳造終了時にタンディッシュ５内に溶融金属６が残留して歩留まり低下を起こさない程度に低い位置とすることが好ましい。   The size of the side hole 2 preferably has a cross-sectional area through which foreign matter having a maximum particle size in the molten metal of about 50 mm can pass. The upper and lower inner wall surfaces of the side hole 2 may be horizontal or inclined, but the height of the side hole 2 is such that the molten metal 6 remains in the tundish 5 at the end of casting. Therefore, it is preferable to set the position so low that the yield does not decrease.

なお、耐火物製構造体１の上端部には、上蓋を設けても設けなくても構わない。   Note that an upper lid may or may not be provided at the upper end of the refractory structure 1.

（２）第２発明
第２発明は、水平方向の円形断面における最大内径が１５０ｍｍ〜３０００ｍｍ、内面の高さが５０ｍｍ〜２０００ｍｍであり、仮想線Ｘ１〜ＸＮに対する側孔２の中心軸の傾斜角度θ１が１５°〜８０°である耐火物製構造体１をタンディッシュ５内に配置して鋳造する第１発明の溶融金属の連続鋳造方法である。 (2) Second invention The second invention has a maximum inner diameter of 150 mm to 3000 mm and an inner surface height of 50 mm to 2000 mm in a horizontal circular cross section, and an inclination angle of the central axis of the side hole 2 with respect to the virtual lines X1 to XN It is the continuous casting method of the molten metal of 1st invention which arrange | positions and casts the structure 1 made from a refractory material whose (theta) 1 is 15 degrees-80 degrees in the tundish 5.

耐火物製構造体１の水平方向の円形断面の最大内径が１５０ｍｍ未満では、旋回流付与機構としては小さ過ぎるので、溶融金属通路の横断面が狭くなり、側孔２の閉塞や溶融金属６の摩擦抵抗の増大などの問題が生じる。また、耐火物製構造体１の円形横断面の最大内直径が３０００ｍｍを超えると、耐火物構造体として過大となるので、耐火物構造体のコストの増加はもちろんのこと、専用のタンディッシュが必要になり、鋳造設備のコスト増大を招く。したがって、耐火物製構造体１の水平方向の円形断面の最大内径は、１５０ｍｍ〜３０００ｍｍの範囲とすることが好ましい。なお、耐火物製構造体１の円形横断面の最大内径のさらに好ましい範囲は、３００ｍｍ〜８００ｍｍである。   When the maximum inner diameter of the horizontal cross section of the refractory structure 1 is less than 150 mm, the swirl flow imparting mechanism is too small, so that the cross section of the molten metal passage is narrowed, the side holes 2 are blocked, the molten metal 6 Problems such as increased frictional resistance arise. In addition, if the maximum inner diameter of the circular cross section of the refractory structure 1 exceeds 3000 mm, the refractory structure becomes excessive, so the cost of the refractory structure increases as well as a dedicated tundish. This is necessary and increases the cost of casting equipment. Therefore, the maximum inner diameter of the horizontal cross section of the refractory structure 1 is preferably in the range of 150 mm to 3000 mm. A more preferable range of the maximum inner diameter of the circular cross section of the refractory structure 1 is 300 mm to 800 mm.

耐火物製構造体１の内面の高さが５０ｍｍ未満では、溶融金属の通路が狭過ぎ、閉塞問題が生じやすくなる。また、耐火物製構造体１の高さは、タンディッシュ５内部の深さにより制約されるので、通常、耐火物製構造体１の内面高さは２０００ｍｍ以内となる。したがって、耐火物製構造体１の内面の高さは５０ｍｍ〜２０００ｍｍの範囲とすることが好ましい。また、耐火物製構造体１の上端部７に上蓋を設けない場合は、上端部７の高さをタンディッシュ５内の湯面高さよりも高くすることが耐火物製構造体１内へのタンディッシュスラグの混入を防止する観点から好ましい。   When the height of the inner surface of the refractory structure 1 is less than 50 mm, the passage of the molten metal is too narrow and a clogging problem is likely to occur. Further, since the height of the refractory structure 1 is limited by the depth inside the tundish 5, the inner surface height of the refractory structure 1 is usually within 2000 mm. Therefore, the height of the inner surface of the refractory structure 1 is preferably in the range of 50 mm to 2000 mm. Further, when the upper cover 7 is not provided on the upper end portion 7 of the refractory structure 1, the height of the upper end portion 7 is set higher than the molten metal surface height in the tundish 5. It is preferable from the viewpoint of preventing the tundish slag from being mixed.

耐火物製構造体１に設けた側孔２の傾斜角度θ１が１５°よりも小さいと付与される旋回流の強さが不足する。一方、傾斜角度θ１が８０°を超えて大きくなると、耐火物製構造体１の側壁の厚みが薄くなるので、強度上の問題が生じる。したがって、側孔２の傾斜角度θ１は１５°〜８０°の範囲とすることが好ましい。   If the inclination angle θ1 of the side hole 2 provided in the refractory structure 1 is smaller than 15 °, the strength of the swirling flow provided is insufficient. On the other hand, when the inclination angle θ1 exceeds 80 °, the thickness of the side wall of the refractory structure 1 is reduced, which causes a problem in strength. Therefore, the inclination angle θ1 of the side hole 2 is preferably in the range of 15 ° to 80 °.

（３）第３発明
第３発明は、耐火物製構造体１の上端部７に開孔部が設けられ、開孔部を通じてタンディッシュの上部から底部まで耐火物製ストッパーロッド１４が配置された耐火物製構造体を用いて鋳造する第１発明または第２発明の溶融金属の連続鋳造方法である。 (3) Third invention In the third invention, an opening is provided in the upper end 7 of the refractory structure 1, and a refractory stopper rod 14 is disposed from the top to the bottom of the tundish through the opening. It is the continuous casting method of the molten metal of 1st invention or 2nd invention cast | casting using a refractory structure.

耐火物製構造体１の内部には溶融金属の旋回流が生じるので、湯面から浸漬ノズル４内にまで到る渦が発生し、タンディッシュ５内湯面上のスラグを吸い込み、鋳型１１内に混入させることがある。この現象を避けるには、耐火物製のストッパーロッド１４を耐火物製構造体１の円形断面の中心部に設置することが有効である。   Since a swirling flow of the molten metal is generated inside the refractory structure 1, a vortex extending from the molten metal surface to the immersion nozzle 4 is generated, and the slag on the molten metal surface in the tundish 5 is sucked into the mold 11. May be mixed. In order to avoid this phenomenon, it is effective to install the refractory stopper rod 14 at the center of the circular cross section of the refractory structure 1.

この場合、上端部に開口部を設けるに当たっては、耐火物製構造体１の形状は円筒状、円錐状または円錐台状のいずれの形状のものであってもよい。また、耐火物製構造体１の上端部７の高さは、タンディッシュ５内の湯面高さよりも低くても構わない。開口部の隙間が多少大きく、そこからスラグが侵入する場合であっても、上記耐火物製ストッパーが備えられていれば、スラグを巻き込む渦は形成されないので、鋳型１１内へのスラグの巻き込みは防止できるからである。   In this case, when the opening is provided at the upper end, the shape of the refractory structure 1 may be any of a cylindrical shape, a conical shape, or a truncated cone shape. Further, the height of the upper end portion 7 of the refractory structure 1 may be lower than the height of the hot water surface in the tundish 5. Even if the gap between the openings is somewhat large and the slag enters from there, if the refractory stopper is provided, the vortex for slag wrapping is not formed, so the slag wrapping into the mold 11 is not This is because it can be prevented.

ストッパーロッド１４は、通常、タンディッシュ５内から浸漬ノズルに到る溶融金属通路の開閉を行うものであるから、鋳造中は、タンディッシュ５の底面から数ｍｍ〜数十ｍｍ上方に、ストッパーロッド１４の下端があり、上端部は、タンディッシュ５の上部に設置された昇降機構に繋がっている。本発明において、ストッパーロッド１４は、旋回流の形成に伴い生じる渦の発生を防止する目的で用いるので、旋回流を減衰させない範囲でタンディッシュ５の底部に近い方が好ましく、ロッドの下端をタンディッシュ５の底面から数十ｍｍ〜１００ｍｍとすることが好ましい。なお、ストッパーロッド１４は通常の昇降機能を有していてもよいし、また、昇降機能を有さずに高さ方向に固定されたロッド（棒）であっても構わない。   Since the stopper rod 14 normally opens and closes the molten metal passage from the inside of the tundish 5 to the immersion nozzle, the stopper rod 14 is several mm to several tens of mm above the bottom of the tundish 5 during casting. 14 has a lower end, and the upper end is connected to an elevating mechanism installed at the top of the tundish 5. In the present invention, the stopper rod 14 is used for the purpose of preventing the generation of vortices caused by the formation of the swirling flow. Therefore, it is preferable that the stopper rod 14 is close to the bottom of the tundish 5 as long as the swirling flow is not attenuated. It is preferable to set it to several tens to 100 mm from the bottom surface of the dish 5. The stopper rod 14 may have a normal lifting function, or may be a rod (rod) fixed in the height direction without having the lifting function.

ストッパーロッド１４が昇降機能を有する場合には、これを鋳型１１内の湯面レベル制御に用いてもよいし、単に、鋳造開始時および終了時に、溶融金属通路の開閉を行うことのみに用いてもよい。ストッパーロッド１４を単に鋳造開始時および終了時に溶融金属通路の開閉を行うことのみに用いる場合には、鋳造中の鋳型１１内湯面レベル制御には、浸漬ノズル４と上ノズル８との間に設けたスライディングゲート９を用いるのが好ましい。   When the stopper rod 14 has a lifting / lowering function, this may be used for controlling the molten metal surface level in the mold 11 or simply for opening and closing the molten metal passage at the start and end of casting. Also good. When the stopper rod 14 is used only for opening and closing the molten metal passage at the start and end of casting, it is provided between the immersion nozzle 4 and the upper nozzle 8 for controlling the level of the molten metal in the mold 11 during casting. The sliding gate 9 is preferably used.

このように、ストッパーロッド１４とスライディングゲート９とを併用する場合には、スライディングゲート９の開度が常に全開に近い領域で制御に用いられるよう、ストッパーロッド１４の高さを調整すると、安定した旋回流が浸漬ノズル４内に生じる。これは、スライディングゲート９の絞りが大きいと、耐火物製構造体１の内部で生じた旋回流が偏心するとともに、減衰するからである。具体的には、例えば、スライディングゲート９の全開状態を１００％としたとき、平均開度が９０％程度に近づくように、過去数十秒から数分程度の平均開度をモニターしながら、緩やかな昇降動作をストッパーロッド１４に加えるように制御を行うことが好ましい。   As described above, when the stopper rod 14 and the sliding gate 9 are used in combination, the height of the stopper rod 14 is adjusted so that the opening degree of the sliding gate 9 is always used for control in a region close to full opening. A swirling flow is generated in the immersion nozzle 4. This is because the swirling flow generated inside the refractory structure 1 is decentered and attenuated if the sliding gate 9 is large in the restriction. Specifically, for example, when the sliding gate 9 is fully opened, the average opening degree is gradually monitored while monitoring the average opening degree from the past several tens of seconds to several minutes so that the average opening degree approaches 90%. It is preferable to perform control so that a simple lifting operation is applied to the stopper rod 14.

（４）第４発明
第４発明は、タンディッシュ５に配置された上ノズル８、スライディングゲート９および浸漬ノズル４のうちの少なくとも１つにおいて、溶融金属６と接するその内壁面から、溶融金属６中に不活性ガス１０を吹き込む第１発明〜第３発明のいずれかに記載の溶融金属の連続鋳造方法である。 (4) Fourth Invention In the fourth invention, at least one of the upper nozzle 8, the sliding gate 9, and the immersion nozzle 4 disposed on the tundish 5 starts from the inner wall surface thereof in contact with the molten metal 6. It is a molten metal continuous casting method according to any one of the first to third inventions in which an inert gas 10 is blown into the inside.

耐火物製構造体１の側孔２を通過することにより形成された溶融金属６の旋回流は、上ノズル８内においてノズル内径の縮小に伴い、角運動量保存の法則にしたがって、一層大きな旋回流速を得る。ここで、大きな旋回流速とは、例えば、１ｍ／ｓ以上の周速度を意味する。   The swirl flow of the molten metal 6 formed by passing through the side hole 2 of the refractory structure 1 is a larger swirl flow velocity in accordance with the law of conservation of angular momentum as the nozzle inner diameter is reduced in the upper nozzle 8. Get. Here, the large turning flow velocity means, for example, a peripheral speed of 1 m / s or more.

このような強い旋回流が生じた状態で、旋回流の周囲、すなわち上ノズル８、スライディングゲート９または浸漬ノズル４の内壁面からＡｒガスなどの不活性ガスを吹き込むと、吹き込まれた不活性ガスが、溶融金属６に作用する遠心力により中心部に向けて吸い出され、周辺部から中心部へと向かう気泡膜を形成し、溶鋼中のＡｌ2Ｏ3などの非金属介在物を効率良く捕捉するので、浸漬ノズル４内への非金属介在物の付着が減少する。気泡膜に捕捉された非金属介在物は、鋳型内で気泡と共に浮上・除去される。上記のような気泡膜形成の観点からは、不活性ガス１０は全周から均等に吹き込むことが好ましい。 When an inert gas such as Ar gas is blown from the periphery of the swirling flow, that is, from the inner wall surface of the upper nozzle 8, the sliding gate 9 or the immersion nozzle 4 in a state where such a strong swirling flow is generated, the blown inert gas is blown. Is sucked out toward the center by centrifugal force acting on the molten metal 6 to form a bubble film from the periphery to the center to efficiently remove non-metallic inclusions such as Al 2 O 3 in the molten steel. Since it captures, adhesion of nonmetallic inclusions in the immersion nozzle 4 is reduced. Nonmetallic inclusions trapped in the bubble film float and are removed together with the bubbles in the mold. From the viewpoint of forming the bubble film as described above, the inert gas 10 is preferably blown evenly from the entire circumference.

本発明の溶融金属の連続鋳造方法の効果につき、さらに実施例に基づいて詳細に説明する。なお、以下の説明では、溶融金属として溶鋼を対象とする。   The effect of the molten metal continuous casting method of the present invention will be described in detail based on examples. In the following description, molten steel is used as the molten metal.

（実施例１）
図１は、前述したとおり、本発明の方法を実施するための連続鋳造装置を模式的に示す図であり、同図（ａ）は、同図（ｂ）におけるＡ−Ａ断面図を表し、同図（ｂ）は連続鋳造装置の縦断面図を表す。同図に示す実施例は、前記第１発明、第２発明および第４発明で規定する条件を満たす実施例である。 Example 1
FIG. 1 is a diagram schematically showing a continuous casting apparatus for carrying out the method of the present invention as described above, and FIG. 1 (a) shows a cross-sectional view taken along line AA in FIG. The figure (b) represents the longitudinal cross-sectional view of a continuous casting apparatus. The embodiment shown in the figure is an embodiment that satisfies the conditions defined in the first invention, the second invention, and the fourth invention.

中空円筒状の耐火物製構造体１は、内径４００ｍｍ、外径５５０ｍｍ、高さ１２００ｍｍのアルミナ−シリカ系耐火物で構成されており、側壁には傾斜角度θ１が４０°、高さが２００ｍｍ、幅が８０ｍｍの側孔２が円周方向に５個、高さ方向に２段設けられている。連続鋳造の定常操業時におけるタンディッシュ５内の湯面高さは、耐火物製構造体１の上端部７よりも２００ｍｍ下部にある。   The hollow cylindrical refractory structure 1 is made of an alumina-silica refractory having an inner diameter of 400 mm, an outer diameter of 550 mm, and a height of 1200 mm. The side wall has an inclination angle θ1 of 40 ° and a height of 200 mm. Five side holes 2 having a width of 80 mm are provided in five steps in the circumferential direction and two steps in the height direction. The height of the molten metal surface in the tundish 5 during the continuous operation of continuous casting is 200 mm lower than the upper end 7 of the refractory structure 1.

図１において、側孔２を通過した溶鋼６は、旋回周速度を付与され、内径の絞られた上ノズル８およびスライディングゲート９を通過する際に、角運動量保存の法則に従って旋回周速度を増し、浸漬ノズル４内において強い旋回流を形成する。浸漬ノズル４内に形成された旋回流は、遠心力の作用により浸漬ノズル４下端近傍の２つの吐出孔から均一に、また均等に吐出され、鋳型１１内において安定した流動を形成する。   In FIG. 1, the molten steel 6 that has passed through the side hole 2 is given a swirling peripheral speed, and when passing through the upper nozzle 8 and the sliding gate 9 with a narrowed inner diameter, the swirling peripheral speed increases according to the law of conservation of angular momentum. A strong swirling flow is formed in the immersion nozzle 4. The swirling flow formed in the immersion nozzle 4 is uniformly and evenly discharged from the two discharge holes in the vicinity of the lower end of the immersion nozzle 4 by the action of centrifugal force, and forms a stable flow in the mold 11.

さらに、二層式スライディングゲート９の上側の固定盤内周部よりＡｒガスが吹き込まれ、溶鋼６に作用する遠心力によりＡｒガスが逆円錐状の気泡膜を形成するので、この気泡膜を横切って流下する溶鋼６中の非金属介在物は、効果的に気泡に捕捉され、気泡とともに鋳型１１内で浮上し除去される。   Further, Ar gas is blown in from the inner periphery of the fixed plate on the upper side of the two-layer sliding gate 9, and Ar gas forms an inverted conical bubble film due to the centrifugal force acting on the molten steel 6. The non-metallic inclusions in the molten steel 6 flowing down are effectively trapped in the bubbles, and floated and removed in the mold 11 together with the bubbles.

上述した鋳型内流動の安定化効果と介在物の捕捉および浮上効果により、清浄な鋼を得ることができるのである。また同時に、旋回流が形成されると、浸漬ノズル４の内壁近傍に流れの淀み域が生じにくいので、非金属介在物の付着による浸漬ノズルの閉塞が生じにくいとうい利点も見出される。   Clean steel can be obtained by the effect of stabilizing the flow in the mold and the effect of capturing and floating the inclusions. At the same time, when a swirl flow is formed, a stagnation region of the flow is unlikely to occur in the vicinity of the inner wall of the immersion nozzle 4, so that there is an advantage that the immersion nozzle is not easily blocked due to adhesion of non-metallic inclusions.

図１に示された耐火物製構造体１は、その上端部７をタンディッシュ５内の湯面よりも高くし、タンディッシュ５内のスラグがその内部に侵入することを防止しているので、耐火物製構造体１の内部に渦が生じても、鋳型１１内にタンディッシュ５内のスラグを巻き込む恐れは少ない。ただし、タンディッシュ５を再使用する場合には、耐火物製構造体１の内部にタンディッシュ５内のスラグが侵入することがあり、発生する渦によってタンディッシュ内のスラグが鋳型１１内に持ち込まれる可能性がある。   Since the refractory structure 1 shown in FIG. 1 has its upper end 7 higher than the hot water surface in the tundish 5 to prevent the slag in the tundish 5 from entering the inside. Even if a vortex is generated inside the refractory structure 1, the slag in the tundish 5 is less likely to be caught in the mold 11. However, when the tundish 5 is reused, the slag in the tundish 5 may enter the refractory structure 1, and the slag in the tundish is brought into the mold 11 by the generated vortex. There is a possibility.

（実施例２）
図２は、本発明の方法を実施するための別の連続鋳造装置を模式的に示す図であり、同図（ａ）は、同図（ｂ）におけるＡ−Ａ断面図を表し、同図（ｂ）は連続鋳造装置の縦断面図を表す。同図に示す実施例は、前記第１発明〜第４発明で規定するいずれの条件をも満たす実施例である。 (Example 2)
FIG. 2 is a view schematically showing another continuous casting apparatus for carrying out the method of the present invention. FIG. 2 (a) is a cross-sectional view taken along line AA in FIG. 2 (b). (B) represents the longitudinal cross-sectional view of a continuous casting apparatus. The embodiment shown in the figure is an embodiment that satisfies any of the conditions defined in the first to fourth inventions.

同図に示されるとおり、中空円錐台状の耐火物製構造体１は、内径が下端部で７００ｍｍ、上端部７で４００ｍｍ、外径が下端部で８６０ｍｍ、上端部７で５６０ｍｍ、内面高さが４００ｍｍ、および外面高さが４８０ｍｍの形状を有し、アルミナ−マグネシア系耐火物で構成されている。その側壁には、同図（ａ）に示すとおり、耐火物製構造体の内面において、仮想線Ｘ１〜Ｘ８に対して側孔の中心軸Ｙ１〜Ｙ８がそれぞれ傾斜角度（θ１）６０°をなし、高さが３００ｍｍ、幅が１００ｍｍの側孔２が８個設けられている。   As shown in the figure, the hollow frustum refractory structure 1 has an inner diameter of 700 mm at the lower end, 400 mm at the upper end 7, an outer diameter of 860 mm at the lower end, 560 mm at the upper end 7, and an inner surface height. Has a shape of 400 mm and an outer surface height of 480 mm, and is made of an alumina-magnesia refractory. On the side wall, as shown in FIG. 6A, the center axes Y1 to Y8 of the side holes form an inclination angle (θ1) of 60 ° with respect to the virtual lines X1 to X8 on the inner surface of the refractory structure. Eight side holes 2 having a height of 300 mm and a width of 100 mm are provided.

また、中空円錐台の上端部７には直径２００ｍｍの開孔部があり、その開孔部を通して直径１００ｍｍのストッパーロッド１４がタンディッシュ５の上方から上ノズル８の近傍まで挿入されている。定常操業時のタンディッシュ５内の湯面高さは、耐火物製構造体１が完全に浸漬する高さとなる。   The upper end portion 7 of the hollow truncated cone has an opening portion having a diameter of 200 mm, and a stopper rod 14 having a diameter of 100 mm is inserted from above the tundish 5 to the vicinity of the upper nozzle 8 through the opening portion. The height of the hot water surface in the tundish 5 during steady operation is a height at which the refractory structure 1 is completely immersed.

図２に示される実施例２においても、前記実施例１の場合と同様に、側孔２を通過した溶鋼６は旋回周速度を付与され、内径の絞られた上ノズル８およびスライディングゲート９を通過する際に、角運動量保存の法則に従って旋回周速度を増し、浸漬ノズル４内に強い旋回流を形成する。浸漬ノズル４内に形成された旋回流は、遠心力の作用により浸漬ノズル４の下端近傍の２つの吐出孔から均一に、また均等に吐出され、安定した鋳型内流動を形成する。   Also in the second embodiment shown in FIG. 2, as in the first embodiment, the molten steel 6 that has passed through the side hole 2 is given a swirling peripheral speed, and the upper nozzle 8 and the sliding gate 9 with a narrowed inner diameter are provided. When passing, the swirling peripheral speed is increased according to the law of conservation of angular momentum, and a strong swirling flow is formed in the immersion nozzle 4. The swirl flow formed in the immersion nozzle 4 is uniformly and evenly discharged from the two discharge holes near the lower end of the immersion nozzle 4 by the action of centrifugal force, thereby forming a stable flow in the mold.

また、上ノズル８の内周部よりＡｒガスが吹き込まれ、このＡｒガスが溶鋼６に作用する遠心力により逆円錐状の気泡膜を形成しているので、この気泡膜を横切って流下する溶鋼６中の非金属介在物は、効果的に気泡に捕捉され、気泡とともに鋳型１１内で浮上し除去される。   Moreover, since Ar gas is blown from the inner peripheral part of the upper nozzle 8, and this Ar gas forms the reverse conical bubble film | membrane with the centrifugal force which acts on the molten steel 6, the molten steel which flows down across this bubble film | membrane The non-metallic inclusions in 6 are effectively trapped in the bubbles, and floated and removed in the mold 11 together with the bubbles.

上述の鋳型内流動の安定化効果と介在物捕捉および浮上効果により、清浄な鋼を得ることができる。また同時に、旋回流が形成されると、浸漬ノズル４の内壁近傍に流れの淀み域が生じにくいので、非金属介在物の付着による浸漬ノズル４の閉塞が生じにくい利点もある。   Clean steel can be obtained by the effect of stabilizing the flow in the mold and the effect of trapping and floating the inclusions. At the same time, when the swirl flow is formed, a stagnation region of the flow is unlikely to occur in the vicinity of the inner wall of the immersion nozzle 4, so that there is an advantage that the immersion nozzle 4 is not easily blocked due to adhesion of non-metallic inclusions.

実施例２においては、ストッパーロッド１４が存在するので、旋回流に起因する渦の発生が防止され、タンディッシュ５内のスラグが鋳型１１内に持ち込まれる可能性は非常に低い。また、ストッパーロッド１４の高さを制御し、スライディングゲート９の開度を鋳型１１内の湯面レベル制御に悪影響を及ぼさない範囲で全開に近づけることによって、旋回流が周方向に高い均等性を保ったままの状態で、溶鋼６を浸漬ノズル４内に流入させることが可能となる。上記の作用により、鋳型内流動をさらに均等に保つ効果が発揮される。   In the second embodiment, since the stopper rod 14 is present, the generation of vortex due to the swirling flow is prevented, and the possibility that the slag in the tundish 5 is brought into the mold 11 is very low. In addition, by controlling the height of the stopper rod 14 and making the opening of the sliding gate 9 close to full opening within a range that does not adversely affect the level control in the mold 11, the swirling flow has a high uniformity in the circumferential direction. The molten steel 6 can be allowed to flow into the immersion nozzle 4 while being maintained. Due to the above action, the effect of maintaining the flow in the mold more evenly is exhibited.

上記の実施例１および実施例２に示した本発明の溶融金属の連続鋳造方法は、耐火物製構造体１を設置しない通常の連続鋳造方法に比較して、浸漬ノズル４内に旋回流を形成でき、また、旋回流付与型浸漬ノズルを使用する鋳造方法に比べても、ノズルの閉塞を防止しながら旋回流を形成できるので、浸漬ノズル４の内壁への非金属介在物付着を確実に抑制できる。したがって、本発明の方法は、鋳型内流動を安定化し、鋳片の高品質化および連続鋳造の生産性向上に大きな効果を発揮する。   The continuous casting method of the molten metal of the present invention shown in the first and second embodiments described above produces a swirling flow in the submerged nozzle 4 as compared with a normal continuous casting method in which the refractory structure 1 is not installed. Compared to the casting method using a swirl flow imparting type immersion nozzle, the swirl flow can be formed while preventing the nozzle from being blocked, so that non-metallic inclusions can be reliably attached to the inner wall of the immersion nozzle 4. Can be suppressed. Therefore, the method of the present invention stabilizes the flow in the mold, and exerts a great effect on improving the quality of slab and improving the productivity of continuous casting.

本発明の方法によれば、旋回羽根を有する旋回流付与浸漬ノズルの欠点であるノズル閉塞を起こすことなく、浸漬ノズル内の溶融金属に旋回流を形成させ、旋回流付与浸漬ノズルが有する、鋳型内溶融金属の優れた流動安定性や、非金属介在物の除去などの効果を享受して、安定した連続鋳造操業および鋳片の品質向上を達成することができる。したがって、本発明の溶融金属の連続鋳造方法は、安価な設備と方法により連続鋳造の安定化および金属鋳片の高清浄度化を目指す精錬および鋳造分野において広範に適用できる技術である。   According to the method of the present invention, without causing the nozzle clogging which is a defect of the swirl flow imparting immersion nozzle having swirl vanes, the swirl flow is formed in the molten metal in the immersion nozzle, and the mold which the swirl flow imparting immersion nozzle has By taking advantage of the excellent flow stability of the inner molten metal and the removal of non-metallic inclusions, it is possible to achieve stable continuous casting operations and improved slab quality. Therefore, the molten metal continuous casting method of the present invention is a technique that can be widely applied in the refining and casting fields aiming at stabilization of continuous casting and high cleanliness of metal slabs by inexpensive equipment and methods.

本発明の方法を実施するための連続鋳造装置を模式的に示す図であり、同図（ａ）は、同図（ｂ）におけるＡ−Ａ断面図を表し、同図（ｂ）は連続鋳造装置の縦断面図を表す。BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the continuous casting apparatus for enforcing the method of this invention, The figure (a) represents AA sectional drawing in the figure (b), The figure (b) is continuous casting. The longitudinal cross-sectional view of an apparatus is represented. 本発明の方法を実施するための別の連続鋳造装置を模式的に示す図であり、同図（ａ）は、同図（ｂ）におけるＡ−Ａ断面図を表し、同図（ｂ）は連続鋳造装置の縦断面図を表す。It is a figure which shows typically another continuous casting apparatus for enforcing the method of this invention, The figure (a) represents the AA sectional drawing in the figure (b), The figure (b) is the figure. The longitudinal cross-sectional view of a continuous casting apparatus is represented.

符号の説明Explanation of symbols

１：耐火物製構造体、 ２：側孔、 ３：耐火物製構造体の軸、 ４：浸漬ノズル、
５：タンディッシュ、 ５１：タンディッシュ耐火物、 ５２：タンディッシュ鉄皮、
６：溶融金属（溶鋼）、 ７：耐火物製構造体の上端部、 ８：上ノズル、
９：スライディングゲート、 １０：不活性ガス、 １１：鋳型、 １２：凝固シェル、
１３：モールドパウダー、 １４：ストッパーロッド、
Ｏ：水平方向の円形断面の中心、 Ｘ１〜Ｘ８：放射状に伸びる仮想線、
Ｙ１〜Ｙ８：側孔の中心軸、 θ１：側孔の傾斜角度、
1: refractory structure, 2: side holes, 3: shaft of refractory structure, 4: immersion nozzle,
5: Tundish, 51: Tundish refractory, 52: Tundish iron skin,
6: Molten metal (molten steel), 7: Upper end of refractory structure, 8: Upper nozzle,
9: sliding gate, 10: inert gas, 11: mold, 12: solidified shell,
13: Mold powder, 14: Stopper rod,
O: center of a circular section in the horizontal direction, X1 to X8: imaginary lines extending radially,
Y1 to Y8: central axis of the side hole, θ1: inclination angle of the side hole,

Claims (4)

側壁に１つ以上の側孔が設けられた中空の円筒状、円錐状または円錐台状の耐火物製構造体であり、該側孔は該耐火物製構造体の水平方向の円形断面の中心から放射状に伸びる仮想線と該耐火物構造体の内面との交点に側孔の出側開口部の中心を有し、該出側開口部において該仮想線に対して側孔の中心軸を傾斜させて設けられた耐火物製構造体を、該耐火物製構造体の軸を鉛直にして、浸漬ノズル上方のタンディッシュ内に配置し、該タンディッシュ内の溶融金属を、耐火物製構造体外面に開口した側孔の入側開口部から耐火物製構造体内面に開口した出側開口部に向かって通過させることにより、該タンディッシュから浸漬ノズル内に供給される溶融金属に旋回流を付与して鋳造することを特徴とする溶融金属の連続鋳造方法。   A hollow cylindrical, conical or frustoconical refractory structure with one or more side holes in the side wall, the side holes being the center of a horizontal circular cross section of the refractory structure The center of the exit opening of the side hole is at the intersection of the virtual line extending radially from the inner surface of the refractory structure, and the center axis of the side hole is inclined with respect to the imaginary line at the exit opening The refractory structure provided is placed in the tundish above the immersion nozzle with the axis of the refractory structure vertical, and the molten metal in the tundish is placed in the refractory structure. A swirl flow is caused to flow from the tundish to the molten metal supplied into the submerged nozzle by passing it from the inlet opening of the side hole opened to the outer surface toward the outlet opening opened to the inner surface of the refractory structure. A method for continuously casting a molten metal, comprising applying and casting. 前記水平方向の円形断面における最大内径が１５０ｍｍ〜３０００ｍｍ、内面の高さが５０ｍｍ〜２０００ｍｍであり、前記出側開口部において仮想線に対して側孔の中心軸のなす角度が１５°〜８０°である耐火物製構造体をタンディッシュ内に配置して鋳造することを特徴とする請求項１に記載の溶融金属の連続鋳造方法。   In the horizontal circular cross section, the maximum inner diameter is 150 mm to 3000 mm, the inner surface height is 50 mm to 2000 mm, and the angle formed by the central axis of the side hole with respect to the imaginary line in the outlet opening is 15 ° to 80 °. 2. The molten metal continuous casting method according to claim 1, wherein said refractory structure is cast in a tundish. 前記耐火物製構造体の上端部に開孔部が設けられ、該開孔部を通じてタンディッシュの上部から底部まで耐火物製ストッパーロッドが配置された耐火物製構造体を用いて鋳造することを特徴とする請求項１または２に記載の溶融金属の連続鋳造方法。   Casting is performed using a refractory structure in which an opening is provided at the upper end of the refractory structure and a refractory stopper rod is disposed from the top to the bottom of the tundish through the opening. The continuous casting method for molten metal according to claim 1 or 2, characterized in that: タンディッシュに配置された上ノズル、スライディングゲートおよび浸漬ノズルのうちの少なくとも１つにおいて、溶融金属と接するその内壁面から、溶融金属中に不活性ガスを吹き込むことを特徴とする請求項１〜３のいずれかに記載の溶融金属の連続鋳造方法。
The inert gas is blown into the molten metal from at least one of the upper nozzle, the sliding gate and the immersion nozzle arranged in the tundish from the inner wall surface in contact with the molten metal. A method for continuously casting a molten metal according to any one of the above.
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