JPH06114521A - Continuous casting method for cast slab having favorable surface - Google Patents

Abstract

PURPOSE:To stably and continuously cast a cast slab having favorable surface characteristic by casting while oscillating a mold wall to the specific oscillating number and the specific ratio of retreating velocity and advancing velocity of the mold wall. CONSTITUTION:By using the vertical type mold for continuous casting forming a rectangular casting space with four pieces of the mold wall surfaces, the continuous casting is executed. In this case, while oscillating at least one pair of the facing surface in the mold wall in the direction crossing at the right angle to the drawing direction of the cast slab at 10-90cpm the number of oscillations, >=0.9mm and <1.0mm the amplitude and >=1.2Vo/Vs ratio of the retreating velocity V and the advancing velocity Vs of the mold wall, the casting is executed. By this method, while executing the stable casting, the oscillation mark is eliminated and the cast slab having good surface condition of shallow surface fold degree can stably be produced.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、金属の連続鋳造、特に
縦型鋳造においてオシレーションマーク深さの低減によ
る偏析、割れ、ノロカミ、ブロー等の欠陥が少ない良好
な表面を有する鋳片を得ることができる連続鋳造方法に
関するものである。INDUSTRIAL APPLICABILITY The present invention provides a slab having a good surface with few defects such as segregation, cracking, scouring, blow, etc. due to the reduction of oscillation mark depth in continuous casting of metal, especially vertical casting. The present invention relates to a continuous casting method that can be performed.

【０００２】[0002]

【従来の技術】従来、連続鋳造は鋳造の安定化のため
に、鋳型を縦方向に振動させつつ鋳片を連続引き抜きす
ることが必須と考えられていた。しかし、この縦方向の
鋳型振動は、鋳片表面に１回の鋳型振動毎にオシレーシ
ョンマークを形成するため、このマークに起因した表面
あるいは表皮下に欠陥、例えばマーク谷部偏析やマーク
に沿った横割れ、マーク爪部へ集積したモールドパウダ
ー噛込み、溶鋼中非金属介在物の表面偏析、ガス気泡が
発生しやすい。よって、このままでは鋳片を圧延でき
ず、鋳片表面の欠陥部を手入れ・除去する必要があり、
歩止まり低下や生産性減少につながっていた。2. Description of the Related Art Conventionally, in continuous casting, it has been considered essential to continuously draw out a slab while vibrating the mold in the longitudinal direction in order to stabilize the casting. However, this vertical mold vibration forms an oscillation mark on the surface of the slab at every single mold vibration. Therefore, defects such as segregation of valleys along the marks or marks along the surface or under the epidermis caused by the marks are formed. Horizontal cracking, biting of mold powder accumulated in the claws of the mark, surface segregation of non-metallic inclusions in molten steel, and gas bubbles are likely to occur. Therefore, the slab cannot be rolled as it is, and it is necessary to care for and remove the defective portion on the slab surface,
This led to lower yields and lower productivity.

【０００３】これらの問題はオシレーションマークの深
さを軽減することによって軽減できる。その方法とし
て、従来鋳型を鋳片引き抜き方向と直交する方向（水平
方向）に 100〜1800cpm の振動数で振動させつつ、鋳造
する方法が特開昭49−123931号公報、特開昭52−136835
号公報や特許第137146号に開示されている。These problems can be alleviated by reducing the depth of the oscillation mark. As a conventional method, there is a method of casting while vibrating the mold at a frequency of 100 to 1800 cpm in the direction (horizontal direction) orthogonal to the slab withdrawal direction, as disclosed in JP-A-49-123931 and JP-A-52-136835.
It is disclosed in Japanese Patent Publication No. 137146 and Japanese Patent No. 137146.

【０００４】[0004]

【発明が解決しようとする課題】鋳型を水平方向にのみ
振動させつつ鋳造する場合、鋳片表面にオシレーション
マークの形成が行われないので、美麗な鋳片が得られる
が、水平方向の振動数ｆが従来のように 100〜1800cpm
の場合、鋳造の安定性に不可欠な鋳型／鋳片間への潤滑
剤（モールドパウダーやレプシードオイル）の供給をス
ムーズに行うことが非常に困難である。When casting while vibrating the mold only in the horizontal direction, no oscillation mark is formed on the surface of the slab, so a beautiful slab can be obtained. Number f is 100 to 1800cpm as before
In this case, it is very difficult to smoothly supply the lubricant (mold powder or repseed oil) between the mold and the slab, which is essential for the stability of casting.

【０００５】よって、長時間の鋳造の場合、連鋳で最大
の事故であるブレークアウトの危険性が高まり、安定鋳
造の点で問題があった。本発明の目的は、ブレークアウ
トの危険性が小さく、かつ表面性状の良好な鋳片の連続
鋳造方法を提案することである。Therefore, in the case of casting for a long time, the risk of breakout, which is the largest accident in continuous casting, increases, and there is a problem in terms of stable casting. An object of the present invention is to propose a continuous casting method of a slab with a low risk of breakout and good surface properties.

【０００６】[0006]

【課題を解決するための手段】本発明は、４枚の鋳型壁
面で矩形の鋳造空間を形成してなる縦形の連続鋳造用鋳
型を用いて連続鋳造するに際して、鋳型壁の少なくとも
一対の相対面をそれぞれ鋳片引き抜き方向と直交する方
向に振動数10〜90 cpm、振巾 0.1mm以上 1.0mm未満で、
かつ鋳型壁の後退速度Ｖ_O と前進速度Ｖ_S との比Ｖ_O ／
Ｖ_S が 1.2以上で振動させつつ鋳造することを特徴とす
る良好な表面を有する鋳片の連続鋳造方法である。DISCLOSURE OF THE INVENTION According to the present invention, in continuous casting using a vertical continuous casting mold in which a rectangular casting space is formed by four mold wall surfaces, at least a pair of relative surfaces of the mold walls are provided. At a frequency of 10 to 90 cpm and a swing range of 0.1 mm or more and less than 1.0 mm in the direction orthogonal to the slab drawing direction,
And the ratio V _O / of the backward velocity V _O and the forward velocity V _S of the mold wall
It is a continuous casting method of a slab having a good surface, which is characterized in that casting is performed while V _S is 1.2 or more while vibrating.

【０００７】[0007]

【作用】鋳型壁を水平方向に振動することによって、鋳
型／鋳片間への潤滑剤の流入挙動は図１（Ｃ）のように
鋳型壁の変位Ｘによって周期的に変動する。潤滑剤の挙
動は、図１（Ｃ）のように鋳型壁が鋳片から遠ざかる
（Ｘの増加）時は、鋳片と鋳型壁で構成されるスリット
内の圧力が負圧になり、これによって矢印Ａの方向に潤
滑剤が流入し、また鋳型壁が鋳片側に近づく時はスリッ
ト内の圧力が増加し、矢印Ｂの方向にスリット内の潤滑
剤が逆に流出する。その量は壁の移動速度に比例すると
考えてよい。By vibrating the mold wall in the horizontal direction, the inflow behavior of the lubricant between the mold and the slab periodically fluctuates according to the displacement X of the mold wall as shown in FIG. 1 (C). The behavior of the lubricant is that when the mold wall moves away from the slab (increase of X) as shown in FIG. 1 (C), the pressure in the slit formed by the slab and the mold wall becomes a negative pressure. The lubricant flows in the direction of arrow A, and when the mold wall approaches the slab, the pressure in the slit increases, and the lubricant in the slit flows out in the direction of arrow B. It can be considered that the amount is proportional to the moving speed of the wall.

【０００８】一方、鋳片は下方にある一定速度Ｖ_C で引
抜かれているので、潤滑剤の一部は下方に流れることに
なる。潤滑剤の流量Ｑは、スリットの間隔Ｘ、鋳型壁の
移動速度Ｖ、鋳片引抜き速度Ｖ_C 、および水平振動サイ
クルｆに影響される。潤滑剤の消費量Ｑ_sum （cm³ ／cy
cle ）という見方をすると、（１）式で表現できる。こ
こでＷは鋳型の周長、Ｖ_d 、Ｖ_u は、鋳型壁を移動した
時の潤滑剤の流入速度（正）、流出速度（負）、ｔ_O 、
ｔ_S は鋳型壁がＸ_S →Ｘ_O 、Ｘ_O →Ｘ _S に移動する時間
を示す。On the other hand, the slab has a constant velocity V below._CPull
Since it has been removed, some of the lubricant will flow downwards.
Become. The flow rate Q of the lubricant is determined by the distance X between the slits and the mold wall.
Moving speed V, slab drawing speed V_C, And horizontal vibration die
It is affected by the crew f. Lubricant consumption Q_sum(cm³/ Cy
From the perspective of cle), it can be expressed by equation (1). This
Where W is the perimeter of the mold, V_d, V_uMoved the mold wall
Inflow speed (positive), outflow speed (negative), t_O,
t_SIs the mold wall X_S→ X_O, X_O→ X _STime to move to
Indicates.

【０００９】[0009]

【数１】 [Equation 1]

【００１０】通常、ｆが大きく、Ｖ_S ＝Ｖ_O （ｔ_O ＝ｔ
_S ／２）の場合、Ｖ_d ＝Ｖ_u （厳密には、Ｖ_C の影響で
Ｖ_d ＞Ｖ_u であるが、わずかに大きい程度）であり、Ｑ
_sumはほぼ０となる。しかし、Ｖ_S ＜Ｖ_O （ｔ_O ＜ｔ_S
／２）の場合、Ｖ_d ＞Ｖ_u となるので、Ｑ_{su m} ＞０とな
る。この場合でも、ｆが大きいとｔ_O 、ｔ_S が小さくな
り、Ｑ_sum はｆが小さい場合に比べて非常に少なくなる
ので、ｆは小さい方がよい。Usually, f is large and V _S = V _O (t _O = t
_In the case of _S / 2), V _d = V _u (strictly, V _d > V _u due to the influence of V _C , but slightly larger), and Q
_sum is almost 0. However, V _S <V _O (t _O <t _S
In the case of / 2), V _d > V _u, and thus Q _{su m} > 0. Even in this case, when f is large, t _O and t _S are small, and Q _sum is much smaller than when f is small. Therefore, it is preferable that f is small.

【００１１】本発明者らは種々の実験の結果、振動数ｆ
が10〜90cpm 、振巾（Ｘ_O −Ｘ_S ）が 0.1mm以上、 1.0
mm未満、かつ鋳型壁の後退速度Ｖ_O と前進速度Ｖ_S との
比Ｖ _O ／Ｖ_S が 1.2以上で良好な表面を有する鋳片を安
定して連続鋳造できることを見出した。それ以外の条件
では、Ｑ_sum が少なく、拘束性ブレークアウトにつなが
る。振巾 1.0mm以上でもＱ_sum は十分であるが、安定鋳
造ができない理由は、組鋳型では、鋳型の合わせ面に湯
差しが発生するためである。As a result of various experiments, the present inventors have found that the frequency f
Is 10 to 90 cpm, swing range (X_O-X_S) Is 0.1 mm or more, 1.0
less than mm and retreat velocity V of mold wall_OAnd forward speed V_SWith
Ratio V _O/ V_SSlabs with a good surface of 1.2 or more
It has been found that it is possible to perform continuous casting with a fixed amount. Other conditions
Then Q_sumAnd lead to a restraint breakout
It Q with a swing width of 1.0 mm or more_sumIs sufficient, but stable casting
The reason why it is not possible to make is that in the case of a combined mold, the mating surface of
This is because there is a gap.

【００１２】[0012]

【実施例】110mm厚、 400mm巾のSUS304、SS41スラブを
Ｖ_C ＝ 0.8〜 2.0ｍ／min 、で鋳造した。この時、長辺
側のみの鋳型壁を振動させつつ鋳造を行った。モールド
パウダーは1300℃での粘度1.2poise，凝固温度 900℃の
カーボンを含まない CaO／SiO₂＝0.6の酸化物系潤滑剤
を使った。EXAMPLE A 110 mm thick, 400 mm wide SUS304, SS41 slab was cast at V _C = 0.8 to 2.0 m / min. At this time, casting was performed while vibrating the mold wall only on the long side. The mold powder used was an oxide-based lubricant with a viscosity of 1.2 poise at 1300 ° C and carbon-free CaO / SiO ₂ = 0.6 with a solidification temperature of 900 ° C.

【００１３】鋳造中には、鋳型壁内部の温度を計測し、
その温度挙動から拘束性ブレークアウト警報を発するよ
うにし、ブレークアウトの危険が発生したら鋳造を中断
するようにした。また、鋳造壁の移動速度Ｖ_O ／Ｖ_S 、
振動数ｆを４〜110 cpm で変化させ振巾を 0.1mm以上
1.0mm未満に保って鋳造を行った。During casting, the temperature inside the mold wall is measured,
A restraint breakout alarm was issued based on the temperature behavior, and casting was interrupted when a risk of breakout occurred. Further, the moving speed V _O / V _{S of} the casting wall,
Change the vibration frequency f from 4 to 110 cpm and make the amplitude 0.1mm or more.
Casting was performed while keeping the thickness to less than 1.0 mm.

【００１４】長辺の鋳型壁１の振動方法は、図３に示す
ように、短辺２クランプ用油圧シリンダ４の開閉を油圧
回路に設けた上下のソレノイババルブ５、６を通じて行
うことによって鋳型の移動を行うものである。７は油圧
モータ、８は油圧タンクを示す。なお、長辺１の移動パ
ターンは図１（Ｃ）のようにそれぞれ同時にほぼ直線的
に移動するよう制御した。As shown in FIG. 3, the method of vibrating the mold wall 1 on the long side is to move the mold by opening and closing the hydraulic cylinder 4 for clamping the short side 2 through upper and lower solenoid valves 5, 6 provided in the hydraulic circuit. Is to do. Reference numeral 7 indicates a hydraulic motor, and 8 indicates a hydraulic tank. The movement pattern of the long side 1 was controlled so as to move substantially linearly at the same time, as shown in FIG.

【００１５】鋳造結果を図２に示すように、Ｖ_O ／Ｖ_S
＜ 1.2、ｆ＝10〜90cpm 、振巾 0.1mm以上 1.0mm未満
で、拘束性ブレークアウト警報もなく、安定して鋳造で
きることが明らかである。なお、Ｖ_O ／Ｖ_S ＝１、ｆ＝
４〜110 cpm は従来法（縦方向振動なし）であるが不安
定な鋳造になることがわかった。また振巾が 0.1mm未満
又は 1.0mm以上の場合には他の条件を満足しても安定な
鋳造ができなかった。[0015] The casting results as shown in FIG. 2, V _O / V _S
<1.2, f = 10 to 90 cpm, swing range of 0.1 mm or more and less than 1.0 mm, and it is clear that stable casting is possible without a restraint breakout warning. Note that V _O / V _S = 1 and f =
It was found that 4-110 cpm was the conventional method (no longitudinal vibration) but unstable casting. When the swing width was less than 0.1 mm or 1.0 mm or more, stable casting could not be achieved even if other conditions were satisfied.

【００１６】鋳造した鋳片の短辺表面の湯じわの深さの
測定結果を表１に示す。比較のために縦振動のある場合
のオシレーションマーク深さを合わせて示した。本発明
の場合、表面の凹みは約0.05mmに対し、従来法−２では
0.35mmであり、表面が美麗であった。なお、従来法−１
の場合、凹み深さは本発明よりもさらに浅く改善されて
いるが、鋳造が不安定なために拘束性ブレークアウトア
ラームが発せられたので、工程的に採用することは危険
である。Table 1 shows the measurement results of the depth of the wrinkle on the surface of the short side of the cast slab. For comparison, the depth of the oscillation mark with vertical vibration is also shown. In the case of the present invention, the surface depression is about 0.05 mm, whereas in the conventional method-2
It was 0.35 mm and the surface was beautiful. Conventional method-1
In the case of No. 3, the depth of the recess was improved to be shallower than that of the present invention, but the restraint breakout alarm was issued due to the instability of casting, so that it is dangerous to adopt it in the process.

【００１７】[0017]

【表１】 [Table 1]

【００１８】なお、本実施例では対向する長辺壁を同時
に対称に振動させたが、それぞれを本発明の条件内で独
立して振動させてもよい。In this embodiment, the opposing long side walls are vibrated symmetrically at the same time, but they may be vibrated independently within the conditions of the present invention.

【００１９】[0019]

【発明の効果】本発明では、安定した鋳造を行いつつオ
シレーションマークを無くし、浅い湯じわ程度の表面状
態の良好な鋳片の安定製造が可能になるので、鋳片圧延
前の鋳片表面手入れを無くす，あるいは軽減できるよう
になる。よって生産性や歩止り向上が達成できる。INDUSTRIAL APPLICABILITY According to the present invention, it is possible to eliminate the oscillation mark while performing stable casting, and to stably produce a slab having a good surface condition such as shallow wrinkle. The surface care can be eliminated or reduced. Therefore, productivity and yield improvement can be achieved.

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

【図１】（ａ）は本発明の説明断面図、（ｂ）は（ａ）
のＰ部の拡大図、（ｃ）は時間に対する潤滑剤の流入
量、鋳型壁の移動速度および変位を示すグラフである。FIG. 1 (a) is an explanatory sectional view of the present invention, and FIG. 1 (b) is (a).
FIG. 3C is an enlarged view of the P part of FIG. 3C, and FIG. 6C is a graph showing the inflow amount of the lubricant, the moving speed and the displacement of the mold wall with respect to time.

【図２】振動数ｆとＶ_O ／Ｖ_S の比がブレークアウト警
報発生に及ぼす状況を示すグラフである。FIG. 2 is a graph showing a situation in which the ratio of frequency f and V _O / V _S influences the occurrence of a breakout alarm.

【図３】本発明に用いる装置の概念図である。FIG. 3 is a conceptual diagram of an apparatus used in the present invention.

【符号の説明】[Explanation of symbols]

１ 長辺側鋳型壁 ２ 短辺側鋳型壁 ４ 油圧シリンダ ５ ソレノイドバルブ ６ ソレノイドバルブ ７ 油圧モータ ８ 油圧タンク 1 long side mold wall 2 short side mold wall 4 hydraulic cylinder 5 solenoid valve 6 solenoid valve 7 hydraulic motor 8 hydraulic tank

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 ４枚の鋳型壁面で矩形の鋳造空間を形成
してなる縦型の連続鋳造用鋳型を用いて連続鋳造するに
際して、鋳型壁の少なくとも一対の相対面をそれぞれ鋳
片引抜き方向と直交する方向に振動数10〜90 cpm、振巾
0.1mm以上 1.0mm未満で、かつ鋳型壁の後退速度Ｖ_O と
前進速度Ｖ_S との比Ｖ_O ／Ｖ_S が 1.2以上で振動させつ
つ鋳造することを特徴とする良好な表面を有する鋳片の
連続鋳造方法。1. When continuous casting is performed using a vertical continuous casting mold in which a rectangular casting space is formed by four mold wall surfaces, at least a pair of relative surfaces of the mold walls are respectively set in a slab drawing direction. Frequency 10-90 cpm, amplitude in orthogonal direction
A slab having a good surface, which is characterized by being oscillated with vibration of 0.1 mm or more and less than 1.0 mm and a ratio V _O / V _S of the backward velocity V _O and the forward velocity V _S of the mold wall being 1.2 or more. Continuous casting method.