JP3147824B2 - Continuous casting method - Google Patents
Continuous casting methodInfo
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- JP3147824B2 JP3147824B2 JP17233897A JP17233897A JP3147824B2 JP 3147824 B2 JP3147824 B2 JP 3147824B2 JP 17233897 A JP17233897 A JP 17233897A JP 17233897 A JP17233897 A JP 17233897A JP 3147824 B2 JP3147824 B2 JP 3147824B2
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- Prior art keywords
- magnetic field
- flow
- mold
- stage
- molten metal
- Prior art date
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Description
【０００１】[0001]
【発明の属する技術分野】この発明は、鋳型内における
溶融金属の非定常流れによるメニスカス湯面の変動を沈
静化させ、鋳造の高速化と鋳片の品質の改善を可能にす
る導電性溶融金属の連続鋳造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive molten metal capable of calming fluctuations of a meniscus level due to an unsteady flow of molten metal in a mold, thereby increasing the speed of casting and improving the quality of a slab. A continuous casting method.
【０００２】[0002]
【従来の技術】金属の連続鋳造方法は、浸漬ノズルを用
いて溶融金属（以下、これを「溶鋼」というときもあ
る）を鋳型内に注入し、連続的に凝固させて鋳片を得る
方法である。浸漬ノズルは鋳型の中心位置に設けられ、
金属板を得る断面長方形の鋳片（スラブ）では、鋳型長
手方向に均一に溶融金属を注入するため、浸漬ノズルの
吐出孔は鋳型断面の長辺に平行な方向に向けて左右に設
けられている。2. Description of the Related Art A continuous casting method of metal is a method of injecting molten metal (hereinafter sometimes referred to as "molten steel") into a mold using an immersion nozzle and continuously solidifying to obtain a cast piece. It is. The immersion nozzle is provided at the center of the mold,
In a slab having a rectangular cross section to obtain a metal plate, in order to uniformly inject molten metal in the longitudinal direction of the mold, the discharge holes of the immersion nozzle are provided on the left and right in a direction parallel to the long side of the mold cross section. I have.
【０００３】連続鋳造が進行すると、浸漬ノズル内に非
金属介在物や地金が付着（ノズル閉塞）して鋳型内の溶
融金属の流れが、ノズル位置の左右で異なる非定常流れ
（以下、これを単に「片流れ」という）が発生すること
がある。[0003] As the continuous casting proceeds, non-metallic inclusions and ingots adhere to the immersion nozzle (nozzle clogging), and the flow of the molten metal in the mold differs between the left and right nozzle positions. Simply referred to as “one-sided flow”).
【０００４】図４は、片流れが発生する原理を説明する
模式図である。浸漬ノズル2から鋳型短辺側壁1Bに向け
て溶融金属を注入すると、吐出流15が発生する。この吐
出流が鋳型短辺側壁に突き当たると、反転して二次上昇
流16と二次下降流18とを生ずる。しかし、左右の吐出量
が異なり、図示するように左側のノズル吐出孔が付着物
19によって閉塞すると溶融金属の流れが左右で対称にな
らず、特に二次上昇流の不均一はメニスカス流17に変動
を与え、メニスカス部の湯面を波打ちさせる。FIG. 4 is a schematic diagram for explaining the principle of one-sided flow. When the molten metal is injected from the immersion nozzle 2 toward the short side wall 1B of the mold, a discharge flow 15 is generated. When this discharge flow hits the side wall of the short side of the mold, it reverses and generates a secondary upward flow 16 and a secondary downward flow 18. However, the left and right discharge amounts are different, and the left nozzle discharge hole is
If the flow is blocked by 19, the flow of the molten metal will not be symmetrical on the left and right, and in particular, the unevenness of the secondary ascending flow will cause the meniscus flow 17 to fluctuate, causing the meniscus portion to undulate.
【０００５】鋳型内で片流れが発生すると、湯面変動が
激しくなり、溶融パウダー11または浸漬ノズルの付着物
が剥離して不純物となり、メニスカス7直下で巻き込ま
れて鋳型壁面近傍で凝固シェル8に捕捉され、鋳片表皮
下欠陥の原因となる。そして冷延鋼板となったとき、た
とえばスリバー疵、ヘゲ疵、ピンホールなどの表皮欠陥
の発生原因となる。[0005] When one-sided flow occurs in the mold, the molten metal surface fluctuates greatly, and the deposits on the molten powder 11 or the immersion nozzle are peeled off and become impurities. This causes slab surface subcutaneous defects. And when it becomes a cold rolled steel plate, it becomes a cause of skin defects such as sliver flaws, scab flaws and pinholes.
【０００６】片流れは、ノズル左右の吐出量が不均一に
なったときに起こるので、これを防止するのはスライデ
ィングゲートでの注入量の調整では困難であり、従来、
鋳造速度を低下させ、溶鋼流動のバランスを安定させる
方法が採られてきた。しかし、鋳造速度を低下させるこ
とは、生産性の低下につながり好ましくない。[0006] Since the one-sided flow occurs when the discharge amounts on the left and right sides of the nozzle become non-uniform, it is difficult to prevent this by adjusting the injection amount with a sliding gate.
Methods have been adopted to reduce the casting speed and stabilize the flow of molten steel. However, lowering the casting speed is undesirable because it leads to lower productivity.
【０００７】片流れはノズル閉塞によって発生するの
で、ノズル閉塞を防止する技術が提案されている。たと
えば、特開平6-179056号公報には、ノズル内部の耐火物
材質をNa2O−低SiO2系として低融点化することによって
付着した不純物を洗い流すようにした浸漬ノズルが提案
されている。[0007] Since the one-sided flow is generated by nozzle blockage, a technique for preventing nozzle blockage has been proposed. For example, JP-A-6-179056, the immersion nozzle has been proposed that the refractory material of the nozzle was set to wash away the impurities attached by low melting point as Na 2 O-low SiO 2 system.
【０００８】[0008]
【発明が解決しようとする課題】本発明の目的は、金属
の連続鋳造に際し、ノズル閉塞により鋳型内の溶融金属
に片流れが発生したときでも、メニスカス部の湯面を安
定させ、ブレークアウトを発生させることなく、かつ表
面欠陥がなく内質の良好な鋳片を製造することができる
連続鋳造方法を提供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to stabilize the molten metal surface of a meniscus portion and generate a breakout even when one-sided flow occurs in the molten metal in a mold due to nozzle blockage during continuous casting of metal. It is an object of the present invention to provide a continuous casting method capable of producing a cast slab with good internal quality without causing any surface defects.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、鋳型内の
溶鋼に片流れが発生したときでも、メニスカス部の湯面
を安定させる方法について研究を行い、鋳型長辺の両側
壁外面の上段、中段および下段に、各段で鋳片の引き抜
き方向から見てコの字形の磁石を異極が対向するように
設けた鋳造装置を用い、各段の静磁場強度を設定する連
続鋳造方法を用いると、湯面が安定することを見いだ
し、本発明を完成した。本発明の要旨は、下記の連続鋳
造方法にある。Means for Solving the Problems The present inventors conducted research on a method of stabilizing the molten metal surface of the meniscus portion even when one-sided flow occurs in the molten steel in the mold, and found that the upper portion of the outer surface of both side walls on the long side of the mold. In the middle and lower stages, a continuous casting method for setting the static magnetic field strength of each stage by using a casting apparatus provided with U-shaped magnets in different stages so that different poles face each other when viewed from the drawing direction of the slab. It was found that when used, the surface of the molten metal was stabilized, and the present invention was completed. The gist of the present invention resides in the following continuous casting method.
【００１０】鋳型1の長辺1Aの外側に下記に示す上段U、
中段Mおよび下段Lに静磁場を印加し、溶融金属を注入し
ながら凝固させる連続鋳造方法であって、鋳型1内の溶
融金属に非定常流れ（片流れ）が発生したとき、これを
検知し、上段および中段に等しい方向の磁場を印加し、
下段には上段および中段の小さい方の磁場強度の0.3倍
から0.7倍までの磁場を印加する連続鋳造方法（図１参
照）。Outside the long side 1A of the mold 1, an upper stage U shown below,
This is a continuous casting method in which a static magnetic field is applied to the middle stage M and the lower stage L, and solidification is performed while pouring the molten metal. When an unsteady flow (single flow) occurs in the molten metal in the mold 1, this is detected. Apply a magnetic field in the same direction to the upper and middle stages,
In the lower stage, a continuous casting method applying a magnetic field of 0.3 to 0.7 times the smaller magnetic field intensity of the upper and middle stages (see Fig. 1).
【００１１】上記の下段には、上段および中段に印加す
る磁場方向と反対方向の磁場を印加するのが望ましい。It is desirable to apply a magnetic field in a direction opposite to the direction of the magnetic field applied to the upper and middle stages to the lower stage.
【００１２】上段：メニスカスを含み、浸漬ノズルから
の吐出流路を含まない上方部分、 中段：浸漬ノズルからの吐出流路を含む中間部分、 下段：浸漬ノズルからの吐出流路を含まない下方部分。Upper part: upper part including meniscus and not including discharge flow path from immersion nozzle, middle part: middle part including discharge flow path from immersion nozzle, lower part: lower part not including discharge flow path from immersion nozzle .
【００１３】ここで、吐出流路とは、静磁場を印加しな
いときの浸漬ノズルから吐出された溶融金属が鋳型短辺
の側壁に衝突するまでの流路である。また、片流れの検
知には、渦流式レベル計を使用することができる。Here, the discharge flow path is a flow path until the molten metal discharged from the immersion nozzle collides with the side wall of the short side of the mold when no static magnetic field is applied. In addition, an eddy current level meter can be used for detecting a single flow.
【００１４】[0014]
【発明の実施の形態】図１は、本発明の連続鋳造方法に
用いた装置の斜視図である。また、図２は、図１のX-X
で示す断面を鋳型の短辺側から見た縦断面図である。FIG. 1 is a perspective view of an apparatus used in a continuous casting method according to the present invention. FIG. 2 is a cross-sectional view of FIG.
FIG. 2 is a longitudinal sectional view of the cross section indicated by the mark as viewed from the short side of the mold.
【００１５】両図において、鋳型1の長辺1Aの両側壁外
面の上段U、中段Mおよび下段Lの３段に鋳込み方向から
見てコの字形の鉄心3Bを配置し、鉄心の平行部3Cにコイ
ル3Aを巻回し、図２に示すように可変抵抗器4を介して
直流電源5を接続する。鋳片1の短辺を挟んで相対する磁
極3Dの極性を反対にして、鋳型1の短辺1B方向に磁場を
形成させる。それぞれのコイル3Aに供給する電流の大き
さ、または方向を変えることによって、磁場強度または
磁場分布を変えることができる。In both figures, a U-shaped iron core 3B as viewed from the casting direction is disposed at three stages of an upper stage U, a middle stage M and a lower stage L on the outer surfaces of both side walls of the long side 1A of the mold 1 and a parallel portion 3C of the iron core. , And a DC power supply 5 is connected via a variable resistor 4 as shown in FIG. A magnetic field is formed in the direction of the short side 1B of the casting mold 1 by inverting the polarity of the magnetic pole 3D opposed to the short side of the slab 1 therebetween. By changing the magnitude or direction of the current supplied to each coil 3A, the magnetic field strength or magnetic field distribution can be changed.
【００１６】上記の３段の領域は、静磁場を印加しない
通常の鋳造状態に基づいて定められる。即ち、前述の図
４に破線で示すように、吐出流15が斜め下方に進行し、
鋳型短辺側1Bの側壁に衝突するまでの流路を「吐出流路
15B」と定義し、中段Mは、この吐出流路15Bの少なくと
も一部を含む位置に設定する。上段Uは、吐出流路15Bを
含まず、それよりも上方にあり、かつ鋳型内溶融金属6
のメニスカス7を含む領域、すなわちメニスカス流17を
含む領域である。下段Lは、吐出流路15Bを含まず、上記
中段Mより下方の領域である。The above three-stage region is determined based on a normal casting state in which no static magnetic field is applied. That is, as shown by the broken line in FIG. 4 described above, the discharge flow 15 proceeds obliquely downward,
The flow path up to collision with the side wall of the mold short side 1B
15B ", and the middle stage M is set at a position including at least a part of the discharge flow path 15B. The upper stage U does not include the discharge flow path 15B, is located above it, and has the molten metal 6 in the mold.
This is a region including the meniscus 7, that is, a region including the meniscus flow 17. The lower stage L does not include the discharge channel 15B and is a region below the middle stage M.
【００１７】図３は、片流れが発生したときに各段の静
磁場強度を変化させて湯面を安定化させた状態を示す鋳
型短辺中心縦断面図である。FIG. 3 is a vertical cross-sectional view of the center of the short side of the mold showing a state where the static magnetic field strength of each stage is changed to stabilize the molten metal surface when a one-sided flow occurs.
【００１８】本発明の連続鋳造方法は、鋳型1内の溶融
金属6に片流れが発生したとき、図１に示す磁場印加装
置を用いて上段Uと中段Mの磁場の印加方向を等しくし、
図３に示すように吐出量の多い片方の吐出流15にブレー
キをかけてメニスカス7を安定させること、および下段L
に印加する静磁場強度を上段および中段よりも小さくし
て二次下降流18に対する二次上昇流16の割合を小さくす
ることにある。吐出量の多い片方の吐出流は、吐出量の
少ない方の吐出流よりも流速が高いので、同じ磁場強度
であっても流速の高い方が抑制力が大きくなる。これに
より、メニスカスでのパウダーの巻き込みや、浸漬ノズ
ル内に付着した不純物が剥離してもパウダーに捕捉さ
れ、鋳型内に巻き込まれることがなく、鋳片の表皮下欠
陥および内質欠陥の発生を防止することができる。In the continuous casting method of the present invention, when a single flow occurs in the molten metal 6 in the mold 1, the directions of application of the magnetic fields of the upper stage U and the middle stage M are made equal using the magnetic field applying device shown in FIG.
As shown in FIG. 3, a brake is applied to one of the discharge flows 15 having a large discharge amount to stabilize the meniscus 7, and
To reduce the ratio of the secondary upflow 16 to the secondary downflow 18 by making the intensity of the static magnetic field applied to the upper and lower stages smaller. Since one of the discharge flows having a larger discharge amount has a higher flow velocity than the discharge flow having a smaller discharge amount, the higher the flow velocity is, the greater the suppression power is, even with the same magnetic field strength. As a result, even if the powder is entangled in the meniscus or impurities adhering to the immersion nozzle are peeled off, the powder is caught by the powder and does not get caught in the mold. Can be prevented.
【００１９】(1)上段および中段に印加する磁場：図５
は、磁力線分布と磁場強度分布を示す図であり、(a)は
全ての段の印加方向を等しくし、下段の磁場強度を小さ
くした場合、(b)は下段の磁場強度を小さくし、かつ印
加方向を反対にした場合、(c)は上段と中段への印加方
向を反対にした場合を示す図である。(1) Magnetic field applied to upper and middle stages: FIG.
Is a diagram showing the distribution of magnetic field lines and the magnetic field intensity distribution, (a) equalize the application direction of all stages, when the lower magnetic field intensity is reduced, (b) is to reduce the lower magnetic field intensity, and (C) is a diagram showing a case where the application direction is reversed, and a case where the application directions to the upper and middle stages are reversed.
【００２０】同図5(a)に示すように、上段および中段へ
の磁場印加は、同方向に印加することによって二次上昇
流の抑制効果を高め、メニスカス部湯面変動を抑制する
ことができる。さらに、同図(b)に示すように、中段と
下段との間に磁場強度がゼロになる領域が存在すると、
二次上昇流の抑制効果を高め、メニスカス部湯面変動を
抑制することができる。しかし、同図(c)に示すように
上段と中段で反対方向に印加すると上段と中段との間で
磁束密度がゼロとなる領域が存在し、湯面変動を抑制で
きなくなる。As shown in FIG. 5 (a), when the magnetic field is applied to the upper stage and the middle stage, by applying the magnetic field in the same direction, the effect of suppressing the secondary ascending flow is enhanced, and the fluctuation of the meniscus portion level is suppressed. it can. Further, as shown in FIG. 3 (b), if there is a region where the magnetic field intensity is zero between the middle and lower stages,
The effect of suppressing the secondary ascending flow can be enhanced, and fluctuations in the meniscus part level can be suppressed. However, when the voltage is applied in the opposite direction between the upper stage and the middle stage as shown in FIG. 3C, there is a region where the magnetic flux density becomes zero between the upper stage and the middle stage, and the fluctuation of the molten metal level cannot be suppressed.
【００２１】静磁場強度の大きさは、鋳型の内壁寸法が
長辺1600mm、短辺270mm、高さ900mmの場合に、上段、中
段のそれぞれで静磁場強度が1500ガウス未満ではその効
果がなく、3000ガウスを超えると二次上昇流が過剰に抑
制されるため、メニスカスへの熱の供給が不足し、温度
低下によるパウダーの不純物捕捉能力が低下する。な
お、上段と中段は、同じ磁場強度でなくともよい。The magnitude of the static magnetic field strength has no effect when the inner wall dimensions of the mold are 1600 mm long side, 270 mm short side, and 900 mm high, and the static magnetic field strength is less than 1500 gauss in each of the upper and middle stages. If it exceeds 3000 gauss, the secondary ascending flow is excessively suppressed, so that the heat supply to the meniscus is insufficient, and the ability of the powder to trap impurities due to a decrease in temperature is reduced. Note that the upper and middle stages need not have the same magnetic field strength.
【００２２】(2)下段に印加する磁場：下段への磁場印
加は、二次下降流の抑制を調整して鋳片の内部欠陥の発
生を低減させる効果がある。そして下段への磁場印加強
度は、上段および中段への磁場印加強度に応じて調整す
る。下段への磁場印加強度は、上段および中段への磁場
印加強度の小さい方の0.3倍未満では鋳片の内部欠陥が
増加する。また、0.7倍を超えると内部欠陥は減少する
が鋳片表面性状（表皮下介在物）が悪化する。したがっ
て、下段への磁場印加強度は、上段および中段への磁場
印加強度の小さい方の0.3倍から0.7倍までの範囲とし
た。(2) Magnetic field applied to the lower stage: The application of the magnetic field to the lower stage has an effect of adjusting the suppression of the secondary descending flow and reducing the occurrence of internal defects in the slab. The intensity of the magnetic field applied to the lower stage is adjusted according to the intensity of the applied magnetic field to the upper and middle stages. If the intensity of the magnetic field applied to the lower stage is less than 0.3 times the smaller of the intensity of the applied magnetic field to the upper stage and the middle stage, the internal defects of the slab increase. On the other hand, when the ratio exceeds 0.7 times, internal defects decrease, but the surface properties of slab (subcutaneous subcutaneous inclusions) deteriorate. Therefore, the intensity of the magnetic field applied to the lower stage was set in a range from 0.3 times to 0.7 times the smaller of the intensity of the applied magnetic field to the upper stage and the middle stage.
【００２３】図３に示すように、鋳造中に片流れが発生
した場合、各段に静磁場を印加したときの鋳型内溶融金
属の流れは次のようになる。As shown in FIG. 3, when one-sided flow occurs during casting, the flow of molten metal in the mold when a static magnetic field is applied to each stage is as follows.
【００２４】不安定な状態となった吐出流15は、中段に
磁場を印加することにより、中段磁極中心線13の位置で
吐出流15の垂直方向成分の流速にブレーキがかかり抑制
され、静磁場強度が低い領域に沿って吐出抑制流15Aが
ほぼ水平方向に生ずる。このとき、左右の吐出流速に差
があり、流速の高いほど磁場印加による抑制力が大きく
なるので、左右の吐出抑制流の流速が等しくなる。浸漬
ノズルの閉塞度合いに応じて中段の静磁場強度を調整す
ると、鋳型短辺側壁1Bに衝突する吐出抑制流15Aの流速
をノズルの左右で安定化させ、メニスカス近傍の凝固シ
ェル8や溶融パウダー11に熱を供給する二次上昇流16が
安定化する。なお、浸漬ノズルの閉塞度合いは、前述し
た片流れの検出方法と同じ方法で検出することができ
る。The unstable flow of the discharge flow 15 is suppressed by applying a magnetic field to the middle stage, so that the flow velocity of the vertical component of the discharge flow 15 at the position of the center line 13 of the middle magnetic pole is braked and the static magnetic field is suppressed. The discharge suppression flow 15A is generated in a substantially horizontal direction along the low intensity region. At this time, there is a difference between the left and right discharge flow velocities, and the higher the flow velocity, the greater the suppression force due to the application of the magnetic field. By adjusting the middle static magnetic field strength according to the degree of blockage of the immersion nozzle, the flow velocity of the discharge suppression flow 15A colliding with the mold short side wall 1B is stabilized on the left and right sides of the nozzle, and the solidified shell 8 and the molten powder 11 near the meniscus are stabilized. Secondary flow 16 that supplies heat to the air is stabilized. In addition, the degree of blockage of the immersion nozzle can be detected by the same method as the above-described method of detecting the one-sided flow.
【００２５】これにより、従来片流れ発生のために不規
則となっていたメニスカス温度の変化が抑制され、安定
した凝固シェルの成長、溶融パウダー11の安定した非金
属介在物（不純物）吸収能の確保ができる。二次上昇流
16は、ほぼ垂直上方に上昇し、静磁場強度が調整された
上段磁極中心線12の位置で、流速が適度に抑制される。
そして、二次上昇抑制流16Aはメニスカス近傍で水平方
向に転じて流速変動のない弱いメニスカス流17を生ず
る。これにより、片流れにより不規則となった吐出流を
安定化させ、湯面変動が抑制され、溶融パウダー11の巻
き込みを防止することができる。As a result, a change in meniscus temperature, which has been irregular due to the occurrence of one-sided flow, is suppressed, and stable solidified shell growth and stable nonmetallic inclusion (impurity) absorption capacity of the molten powder 11 are ensured. Can be. Secondary upflow
Numeral 16 rises almost vertically upward, and at the position of the upper magnetic pole center line 12 where the static magnetic field intensity is adjusted, the flow velocity is moderately suppressed.
Then, the secondary rise suppressing flow 16A turns in the horizontal direction near the meniscus to generate a weak meniscus flow 17 having no flow velocity fluctuation. This stabilizes the discharge flow that has become irregular due to the one-sided flow, suppresses fluctuations in the molten metal level, and prevents the molten powder 11 from being entrained.
【００２６】上段および中段の磁場印加強度の設定に関
しては、上段および中段へ同一方向に磁場を印加するこ
とにより、二次上昇流抑制効果を高め、鋳型内メニスカ
ス部湯面変動を効果的に抑制することが可能となる。Regarding the setting of the magnetic field application strength in the upper and middle stages, the effect of suppressing the secondary upward flow is enhanced by applying a magnetic field in the same direction to the upper and middle stages, thereby effectively suppressing the fluctuation of the mold surface in the meniscus in the mold. It is possible to do.
【００２７】吐出抑制流15Aが鋳型短辺側壁1Bに衝突し
反転して生ずる二次下降流18は、垂直方向に下降し、中
段磁極中心線13の位置で弱い二次下降抑制流18Aを生じ
る。この抑制流は、静磁場強度が調整された下段磁極中
心線14の位置で失速する。これにより、二次下降流18に
随伴して下降する非金属介在物（不純物）や気泡が鋳片
9の内部に侵入し、浮上しないまま捕捉されるのを防止
する。The secondary descending flow 18 that is generated by the discharge suppressing flow 15A colliding with the short side wall 1B of the mold and reversing, descends vertically, and generates a weak secondary descending suppressing flow 18A at the position of the middle magnetic pole center line 13. . This suppression flow stalls at the position of the lower magnetic pole center line 14 where the static magnetic field strength is adjusted. As a result, non-metallic inclusions (impurities) and air bubbles descending along with the secondary descending flow 18 are cast slabs.
Infiltrate the interior of 9 and prevent it from being caught without ascending.
【００２８】下段の磁場印加強度は、上段および中段の
それよりも小さく設定することにより鋳型内溶融金属の
流動制御を行い、鋳片内部欠陥を抑制することが可能と
なる。By setting the lower magnetic field application strength smaller than that of the upper and middle stages, the flow of the molten metal in the mold can be controlled, and the defects in the slab can be suppressed.
【００２９】上述したように、本発明方法によれば、鋳
造中に発生する溶融金属の片流れ発生時に鋳造速度を落
とすことなく、鋳型内の溶融金属に所定の流れを形成す
ることにより、表面性状、内質が良好な鋳片を製造する
ことができる。As described above, according to the method of the present invention, a predetermined flow is formed in the molten metal in the mold without lowering the casting speed at the time of the one-sided flow of the molten metal generated during casting. Thus, it is possible to manufacture a cast piece having a good internal quality.
【００３０】[0030]
【実施例】内壁寸法が長辺幅1600mm、短辺幅 270mm、高
さ 900 mm の水冷銅鋳型を備えた図１に示すスラブ連続
鋳造機を用い、上段と下段にそれぞれ2200ガウス、中段
に3000ガウスの磁場を印加し、低炭素アルミキルド鋼を
スループット6.7トン／分の条件で鋳造試験を行った。
鋳造中に片流れの発生を渦流式湯面レベル計によって検
知し、上段、中段および下段の静磁場強度を表１に示す
ように変化させた。EXAMPLE A continuous slab casting machine as shown in FIG. 1 equipped with a water-cooled copper mold having inner wall dimensions of 1600 mm long side width, 270 mm short side width and 900 mm height was used. A Gaussian magnetic field was applied, and a low carbon aluminum killed steel was subjected to a casting test at a throughput of 6.7 tons / min.
The occurrence of one-sided flow during casting was detected by an eddy current level gauge, and the static magnetic field strengths in the upper, middle and lower stages were changed as shown in Table 1.
【００３１】「スループット」とは、（鋳型の水平断面
積）×（鋳片引き抜き速度）×（比重）によって計算さ
れる溶融金属量である。The “throughput” is the amount of molten metal calculated by (the horizontal sectional area of the mold) × (the speed of drawing the slab) × (the specific gravity).
【００３２】[0032]
【表１】 [Table 1]
【００３３】発明例のチャージNo.1〜7では、上段およ
び中段への磁場印加方向を等しくし、磁場強度を1500〜
3000ガウスの範囲内に変えて印加した。下段への磁場印
加強度は、上段および中段の0.3倍から0.67倍までの範
囲の磁場を印加した。In the charge Nos. 1 to 7 of the invention, the directions of applying the magnetic field to the upper stage and the middle stage are equal, and the magnetic field intensity is 1500 to
The applied voltage was changed within the range of 3000 Gauss. The intensity of the magnetic field applied to the lower stage was 0.3 to 0.67 times that of the upper and middle stages.
【００３４】比較例１のチャージ8および9は、上段また
は中段に反対方向の磁場を印加した。比較例２のチャー
ジ10および11は、上段に1000ガウスまたは3500ガウス
（本発明で定める範囲外の磁場強度）を印加した。比較
例３のチャージ12および13は、下段の磁場強度が上段お
よび中段の0.25倍または1.0倍の磁場を印加した場合
で、いずれも上段および中段との磁場強度割合が、本発
明で定める範囲外とした場合である。For Charges 8 and 9 of Comparative Example 1, a magnetic field in the opposite direction was applied to the upper or middle stage. Charges 10 and 11 of Comparative Example 2 applied 1000 Gauss or 3500 Gauss (magnetic field strength outside the range defined in the present invention) to the upper stage. Charges 12 and 13 of Comparative Example 3 were applied when the magnetic field strength of the lower stage was 0.25 times or 1.0 times that of the upper and middle stages, and the magnetic field intensity ratio between the upper stage and the middle stage was outside the range defined by the present invention. Is the case.
【００３５】湯面変動指数は、渦流式湯面レベル計によ
って測定し、チャージNo.13を基準値１とし、その相対
値で示し、その値が1.0よりも小さい方が良好である。The level change index is measured by an eddy current level gauge, and the charge No. 13 is set as a reference value 1 and is shown as a relative value. It is better that the value is smaller than 1.0.
【００３６】鋳片内介在物指数は、顕微鏡により大きさ
20μｍ以上の介在物個数を計量し、チャージNo.13を基
準値１とし、その相対値で示し、その値が1.0よりも小
さい方が良好である。The inclusion index in the slab is measured by a microscope.
The number of inclusions having a size of 20 μm or more is weighed, and charge No. 13 is set as a reference value 1, which is shown as a relative value. It is better that the value is smaller than 1.0.
【００３７】表面清浄指数は、鋳片の表面から10mm以内
の領域について、顕微鏡により鋳片内の20μｍ以上の介
在物個数を計量し、チャージNo.13を基準値１とし、そ
の相対値で示し、その値が1.0よりも小さい方が良好で
ある。The surface cleanliness index is expressed as a relative value with charge No. 13 as a reference value 1 by measuring the number of inclusions of 20 μm or more in the slab with a microscope in a region within 10 mm from the surface of the slab. It is better that the value is smaller than 1.0.
【００３８】これらの結果を表１に併せて示した。The results are shown in Table 1.
【００３９】発明例のチャージNo.1〜7では、湯面変動
指数が0.6〜0.9の範囲、鋳片内介在物指数が0.7〜1.0の
範囲、表面性状指数が0.6〜0.9の範囲にあり良好であ
る。また、チャージNo.2、4および7に示すように下段の
磁場印加方向を反対にした場合でも良好である。図5(b)
に示すように磁場を中段と下段で反対方向に印加する
と、中段と下段との間で磁束密度がゼロとなり、二次下
降流の抑制を低減し、鋳片内介在物指数が僅かに増加す
る傾向がみられた。これらの発明例のなかでは、チャー
ジNo.7が最も改善されているといえる。In the charge Nos. 1 to 7 of the invention examples, the melt surface fluctuation index is in the range of 0.6 to 0.9, the inclusion index in the slab is in the range of 0.7 to 1.0, and the surface property index is in the range of 0.6 to 0.9. It is. Also, as shown in Charge Nos. 2, 4 and 7, the case where the direction of application of the lower magnetic field is reversed is satisfactory. Fig. 5 (b)
When the magnetic field is applied in the opposite direction in the middle and lower stages as shown in, the magnetic flux density becomes zero between the middle and lower stages, reducing the suppression of the secondary descending flow and slightly increasing the inclusion index in the slab. There was a tendency. Among these invention examples, it can be said that the charge No. 7 is the most improved.
【００４０】これに対し、比較例１のチャージNo.8およ
び9は、上段と中段の磁場印加方向をそれぞれ反対にし
ているため、湯面変動指数がいずれも1.3と大きく、表
面清浄指数も1.2と高く悪化している。これは図5(c)に
示すように、上段と中段の磁場印加方向を反対にする
と、上段と中段の間で磁束密度がゼロとなる領域が存在
する。そのため、上段と中段の間で溶鋼の流速が抑制で
きない領域が存在し、上段に2000ガウスの静磁場を印可
しても湯面変動を抑制できないと考えられる。On the other hand, in Charge Nos. 8 and 9 of Comparative Example 1, since the upper and middle magnetic fields were applied in opposite directions, respectively, the index of change in the molten metal level was as large as 1.3 and the index of cleanliness of the surface was also 1.2. And is getting worse. This is because, as shown in FIG. 5 (c), there is a region where the magnetic flux density becomes zero between the upper stage and the middle stage when the magnetic field application directions of the upper stage and the middle stage are reversed. Therefore, there is a region between the upper stage and the middle stage where the flow velocity of the molten steel cannot be suppressed, and it is considered that even if a static magnetic field of 2,000 Gauss is applied to the upper stage, the fluctuation of the molten metal level cannot be suppressed.
【００４１】比較例２のチャージNo.10では、上段に100
0ガウスの磁場を印加したので磁場が小さく、湯面変動
指数が1.1、鋳片内介在物指数が1.1および表面性状指数
が1.1といずれも大きく、悪化している。チャージNo.11
では、上段に3500ガウスの磁場を印加したので磁場強度
が大きく、湯面変動指数が0.8、鋳片内介在物指数が0.9
と良好であるが、二次上昇流が過大に抑制されるためメ
ニスカス部への熱供給が不十分となり表面清浄指数が1.
1と悪化している。In the charge No. 10 of Comparative Example 2, 100
Since a magnetic field of 0 gauss was applied, the magnetic field was small, and the surface level index was 1.1, the inclusion index in the slab was 1.1, and the surface property index was 1.1. Charge No.11
In the above, a magnetic field strength of 3500 gauss was applied to the upper stage, so the magnetic field strength was large, the melt level index was 0.8, and the inclusion index in the slab was 0.9.
However, since the secondary ascending flow is excessively suppressed, the heat supply to the meniscus is insufficient and the surface cleaning index is 1.
One and worse.
【００４２】比較例３のチャージNo.12では、下段に上
段および中段の0.25倍（500ガウス）の磁場強度を印加
したので湯面変動指数は0.9、表面清浄指数が0.9と良好
であるが、二次下降流の抑制が不十分なため、鋳片内介
在物指数が1.2と悪化した。チャージNo.13は、下段の磁
場強度が上段と同じ（1.0倍、2200ガウス）とし、中段
を3000ガウスとしたため、下降流の抑制が強くなり、湯
面変動を大きくしたものと考えられる。In the charge No. 12 of Comparative Example 3, since the magnetic field strength of 0.25 times (500 gauss) was applied to the lower stage and the upper and middle stages, the surface level variation index was 0.9 and the surface cleaning index was 0.9. The inclusion index in the slab deteriorated to 1.2 due to insufficient suppression of the secondary descending flow. It is considered that Charge No. 13 had the same magnetic field intensity in the lower stage (1.0 times, 2200 gauss) as the upper stage and 3000 gauss in the middle stage, so that the downflow was more strongly suppressed and the surface level fluctuation was increased.
【００４３】[0043]
【発明の効果】本発明の方法によれば、連続鋳造中の鋳
型内の溶融金属に片流れが発生した場合、上段、中段お
よび下段に配置した磁場印加装置によって、それぞれの
磁場印加強度を調整することにより、メニスカス湯面を
沈静化させ、鋳片の表面欠陥や内部欠陥の発生を低減す
ることができる。また、片流れが発生しても鋳造速度を
低下させる必要がないので、生産性が向上する。本発明
は、普通鋼の鋳造のみならず、ステンレス鋼や銅のよう
な非鉄金属の連続鋳造にも適用することができる。According to the method of the present invention, when one-sided flow occurs in the molten metal in the mold during continuous casting, the intensity of the applied magnetic field is adjusted by the magnetic field applying devices arranged in the upper, middle and lower stages. Thereby, the meniscus surface can be calmed down, and the occurrence of surface defects and internal defects of the slab can be reduced. Further, even if one-sided flow occurs, it is not necessary to lower the casting speed, so that productivity is improved. The present invention can be applied not only to casting of ordinary steel, but also to continuous casting of non-ferrous metals such as stainless steel and copper.
【図１】本発明の連続鋳造方法に用いた装置の斜視図で
ある。FIG. 1 is a perspective view of an apparatus used for a continuous casting method of the present invention.
【図２】図１のX-Xで示す断面を鋳型の短辺側から見た
縦断面図である。FIG. 2 is a longitudinal sectional view of the section indicated by XX in FIG. 1 as viewed from the short side of the mold.
【図３】片流れが発生したときに各段の静磁場強度を変
化させて湯面を安定化させた状態を示す鋳型短辺中心縦
断面図である。FIG. 3 is a vertical cross-sectional view of a center of a short side of a mold, showing a state in which the static magnetic field strength of each stage is changed and a molten metal surface is stabilized when a one-sided flow occurs.
【図４】片流れが発生する原理を説明する模式図であ
る。FIG. 4 is a schematic diagram illustrating the principle of generating a one-sided flow.
【図５】磁力線分布と磁場強度分布を示す図であり、
(a)は全ての段の印加方向を等しくし、下段の磁場強度
を小さくした場合、(b)は下段の磁場強度を小さくし、
かつ印加方向を反対にした場合、(c)は上段と中段への
印加方向を反対にした場合を示す図である。FIG. 5 is a diagram showing a magnetic field line distribution and a magnetic field intensity distribution;
(a) equalizes the application direction of all stages and reduces the magnetic field strength of the lower stage, (b) reduces the magnetic field intensity of the lower stage,
(C) is a diagram illustrating a case where the application direction is reversed, and an application direction to the upper and middle stages is reversed.
１：鋳型 1A：鋳型長辺側壁 1B：鋳型短辺側壁 ２：浸漬ノズル ３：電磁石 3A：コイル 3B：鉄心 ４：可変抵抗器 ５：直流電源 ６：溶融金属 ７：メニスカス ８：凝固シェル ９：鋳片 10：固体パウダー 11：溶融パウダー 12：上段磁極中心線 13：中段磁極中心線 14：下段磁極中心線 15：吐出流 15A：吐出抑制
流 16：二次上昇流 16A：二次上昇抑制流 17：メニスカス流 18：二次下降流 18A：二次下降抑制流 19．付着物1: Mold 1A: Mold long side wall 1B: Mold short side wall 2: Immersion nozzle 3: Electromagnet 3A: Coil 3B: Iron core 4: Variable resistor 5: DC power supply 6: Molten metal 7: Meniscus 8: Solidified shell 9: Slab 10: Solid powder 11: Melting powder 12: Upper magnetic pole center line 13: Middle magnetic pole center line 14: Lower magnetic pole center line 15: Discharge flow 15A: Discharge suppression flow 16: Secondary rising flow 16A: Secondary rising suppression flow 17: Meniscus flow 18: Secondary descending flow 18A: Secondary descending suppressing flow 19. Fouling
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平８−10917（ＪＰ，Ａ) 特開 平２−117756（ＪＰ，Ａ) 特開 平４−84650（ＪＰ，Ａ) 特開 平３−275256（ＪＰ，Ａ) 特開 平５−154621（ＪＰ，Ａ) 特開 平６−179056（ＪＰ，Ａ) 特開 平９−174216（ＪＰ，Ａ) 特開 平11−10290（ＪＰ，Ａ) 特開 平６−344080（ＪＰ，Ａ) 特開 昭56−154267（ＪＰ，Ａ) 特開 平６−23503（ＪＰ，Ａ) 特開 平８−229649（ＪＰ，Ａ) 特開 平３−258441（ＪＰ，Ａ) 特開 平２−89544（ＪＰ，Ａ) 特表 平11−502466（ＪＰ，Ａ) 特表 平10−505792（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B22D 11/115 B22D 11/04 311 B22D 11/16 104 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-10917 (JP, A) JP-A-2-117756 (JP, A) JP-A-4-84650 (JP, A) JP-A-3-3 275256 (JP, A) JP-A-5-154621 (JP, A) JP-A-6-179056 (JP, A) JP-A-9-174216 (JP, A) JP-A-11-10290 (JP, A) JP-A-6-344080 (JP, A) JP-A-56-154267 (JP, A) JP-A-6-23503 (JP, A) JP-A 8-229649 (JP, A) JP-A-3-258441 (JP, A) JP-A-2-89544 (JP, A) JP 11-502466 (JP, A) JP 10-505792 (JP, A) (58) Fields investigated (Int. Cl. 7) , DB name) B22D 11/115 B22D 11/04 311 B22D 11/16 104
Claims (2)
び下段に静磁場を印加し、溶融金属を注入しながら凝固
させる連続鋳造方法であって、鋳型内の溶融金属に非定
常流れが発生したとき、これを検知し、上段および中段
には等しい方向の磁場を印加し、下段には上段および中
段の小さい方の磁場強度の0.3倍から0.7倍までの範囲の
磁場を印加することを特徴とする連続鋳造方法。 上段：メニスカスを含み、浸漬ノズルからの吐出流路を
含まない上方部分、 中段：浸漬ノズルからの吐出流路を含む中間部分、 下段：浸漬ノズルからの吐出流路を含まない下方部分。 ここで、吐出流路とは、静磁場を印加しないときの浸漬
ノズルから吐出された溶融金属が鋳型短辺の側壁に衝突
するまでの流路である。1. A continuous casting method in which a static magnetic field is applied to the following upper, middle and lower stages on the outer side of a long side of a mold to solidify while injecting molten metal. When it is generated, it is detected that a magnetic field in the same direction is applied to the upper and middle stages, and a magnetic field in the range of 0.3 to 0.7 times the smaller magnetic field intensity of the upper and middle stages is applied to the lower stage. Characteristic continuous casting method. Upper part: upper part including meniscus and not including discharge flow path from immersion nozzle, middle part: middle part including discharge flow path from immersion nozzle, lower part: lower part not including discharge flow path from immersion nozzle. Here, the discharge flow path is a flow path until the molten metal discharged from the immersion nozzle collides with the side wall of the short side of the mold when no static magnetic field is applied.
加方向と反対方向の磁場を印加することを特徴とする請
求項１に記載の連続鋳造方法。2. The continuous casting method according to claim 1, wherein a magnetic field in a direction opposite to a direction in which a magnetic field is applied to the upper and middle stages is applied to the lower stage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17233897A JP3147824B2 (en) | 1997-06-27 | 1997-06-27 | Continuous casting method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17233897A JP3147824B2 (en) | 1997-06-27 | 1997-06-27 | Continuous casting method |
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| Publication Number | Publication Date |
|---|---|
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| JP3147824B2 true JP3147824B2 (en) | 2001-03-19 |
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| Country | Link |
|---|---|
| JP (1) | JP3147824B2 (en) |
-
1997
- 1997-06-27 JP JP17233897A patent/JP3147824B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH1110295A (en) | 1999-01-19 |
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