JPH0531559A - Detection of solidified end period part in cast slab continuously cast - Google Patents

Abstract

PURPOSE:To make thermal influence from a high temp. cast slab comparatively little and to precisely detect the solidified end period part in the cast slab continuously cast under condition of non-destruction. CONSTITUTION:Laser beam system, eddy current system or the other system distance sensors 2A, 2B are set with the prescribed interval in center part and edge parts of the cast slab S, at between rolls 1, 1... drawn with a cast slab guide roll 1, and bulging quantity is measured with difference between both measured values in the distance sensor 2A set at the center part and the distance sensor 2B set at the edge part in the cast slab S. By comparing the bulging quantity obtd. with this measurement and the bulging quantity beforehand obtd. with calculation in the same position, the solidified end period part is detected. Rolling reduction in the accurate range to the cast slab continuously cast is executed and the good quality cast slab to segregation and internal crack can be obtd.

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、連続鋳造設備の鋳型か
らその下方に設けられた鋳片案内ロール間に引抜かれた
鋳片の凝固末期部を検出する方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a final solidification stage of a cast piece drawn from a mold of a continuous casting facility between a cast guide roll provided below the mold.

【０００２】[0002]

【従来の技術】連続鋳造される鋳片の凝固末期部（固相
率がほぼ 0.3〜 0.8の間）に適正な圧下あるいは電磁攪
拌を加えると鋳片の偏析が改善されることが知られてお
り、このような改善効果を得るために鋳片の凝固開始位
置（固相率 0.3前後）あるいは凝固完了位置（固相率
0.8以上）を知ることは操業上たいへん重要なこととさ
れている。2. Description of the Related Art It is known that segregation of a slab can be improved by applying appropriate pressure reduction or electromagnetic stirring to the final solidification stage (solid phase ratio is approximately 0.3 to 0.8) of a continuously cast slab. In order to obtain such an improvement effect, the solidification start position (solid phase ratio around 0.3) or the solidification completion position (solid phase ratio) of the slab is obtained.
It is said that it is very important for the operation to know (0.8 or more).

【０００３】一般的にこれまで凝固末期部を知る方法と
して以下に示す技術が提案されている。 鋳片内に鋲を打ち込む方法。 この方法は、トレーサーを埋め込んだ鋲を鋳造中の鋳片
内に打ち込み、トレーサーの未凝固部位での拡散を利用
して鋳片の凝固進展を予測し、これより凝固末期部を予
測する方法である。Generally, the following techniques have been proposed as a method of knowing the final stage of coagulation. A method of driving tacks into a slab. This method is a method of driving a stud embedded with a tracer into a slab during casting, predicting the solidification progress of the slab by utilizing diffusion at the unsolidified portion of the tracer, and predicting the final solidification stage from this. is there.

【０００４】ロール反力をロードセルで検知する方
法。 この方法は、鋳片案内ロールの軸受け部に設置されたロ
ードセルにより、上下の鋳片案内ロール間を通過する鋳
片の凝固進展に伴う変形抵抗の変化を測定して凝固完了
位置を検知し、これより凝固末期部を検出する方法であ
る。A method of detecting a roll reaction force with a load cell. This method, by the load cell installed in the bearing portion of the slab guide roll, to detect the solidification completion position by measuring the change in deformation resistance with the solidification progress of the slab passing between the upper and lower slab guide rolls, This is a method of detecting the final stage of coagulation.

【０００５】超音波の透過差より検知する方法 この方法は、鋳片内の液体と固体の部位で超音波の伝播
速度が異なることを利用して凝固開始位置を検知し、こ
れより凝固末期部を検出する方法である。Method of Detecting from Ultrasonic Transmission Difference This method detects the solidification start position by utilizing the fact that the propagation speed of ultrasonic waves is different between the liquid and solid parts in the slab, and from this the final solidification part is detected. Is a method of detecting.

【０００６】[0006]

【発明が解決しようとする課題】ところで、近年連続鋳
造される鋳片の凝固末期部に圧下を加え鋳片の偏析改善
を図る技術が注目され実用化に向けて開発されつつあ
る。しかし、この技術で安定した偏析の改善効果を得る
ためには凝固開始位置から凝固完了位置に当たる凝固末
期部を検出し、この凝固末期部の有効な範囲で鋳片に圧
下を加えなくてはならない。また、この偏析改善に有効
な圧下範囲は相当狭い範囲に限定されることが知られて
いる。By the way, in recent years, a technique for reducing segregation of a slab by applying a reduction to the final solidification portion of the slab that is continuously cast has been drawing attention and is being developed for practical use. However, in order to obtain a stable improvement effect of segregation with this technique, it is necessary to detect the solidification end point from the solidification start position to the solidification completion position and apply the reduction to the slab within the effective range of this solidification end position. . Further, it is known that the reduction range effective for improving the segregation is limited to a considerably narrow range.

【０００７】このため、前述したような種々の方法で凝
固末期部を正確に検出しようとする試みがなされている
ものの、の方法は、破壊検査であること解析に時間が
かかることなどの問題があり、またの方法は、ロール
を介して間接的に凝固完了位置を推定しようとするもの
で感度の点で問題があり、さらにの方法は、高温の鋳
片へ端子を接触させる必要があるためその耐用性などに
問題があって、いずれも凝固末期部を正確に検出するこ
とは難しい。For this reason, although attempts have been made to accurately detect the final stage of coagulation by the various methods as described above, the method has a problem that it is a destructive test and analysis takes time. However, the other method is an attempt to indirectly estimate the solidification completion position via a roll, which has a problem in sensitivity, and the further method requires that the terminal be brought into contact with a hot slab. Since there is a problem in its durability and the like, it is difficult to accurately detect the final stage of coagulation in both cases.

【０００８】本発明は、上記の事情に鑑みてなされたも
のであって、高温鋳片からの熱影響が比較的少なく、且
つ非破壊状態で凝固開始位置を検知し、これにより凝固
末期部を正確に検出する方法を提供するものである。The present invention has been made in view of the above circumstances, and detects the solidification start position in a non-destructive state in which the influence of heat from a high temperature cast slab is relatively small, and thereby the final solidification stage is detected. It provides a method of accurate detection.

【０００９】[0009]

【課題を解決するための手段】上記の目的を達成するた
めに、本発明に関わる連続鋳造される鋳片の凝固末期部
の検出方法は、鋳片案内ロール間の鋳片のバルジング量
を引抜き方向の複数個所で測定し、この測定により得ら
れたバルジング量と予め計算により求めた同一個所にお
けるバルジング量との比較により鋳片の凝固末期部を検
出するものである。In order to achieve the above object, a method for detecting a final solidification stage of a continuously cast slab according to the present invention is to extract a bulging amount of the slab between slab guide rolls. The final solidification portion of the cast slab is detected by comparing the bulging amount obtained by this measurement with the bulging amount obtained at the same position obtained by calculation in advance.

【００１０】[0010]

【作用】以下本発明について詳細に説明する。本発明
は、鋳片の鋳片案内ロール間でのバルジング量が、鋳片
の溶鋼静圧と直接的に結びついていること、溶鋼静圧の
発現の有無が凝固末期部と密接な関係があることに着目
してなしたものである。The present invention will be described in detail below. The present invention is that the bulging amount between the slab guide rolls of the slab is directly connected to the molten steel static pressure of the slab, and the presence or absence of the molten steel static pressure is closely related to the final solidification stage. It was made paying attention to that.

【００１１】鋳片のバルジング量の測定は、図１に示す
ように、鋳片案内ロール１によって引抜かれるロール
１，１，------間の鋳片Ｓの中央部と端部のそれぞれに
所定間隔を開けて、レーザ方式あるいは渦流方式などの
距離センサ2A, 2Bを設置し、鋳片Ｓの中央部に設置した
距離センサ2Aと端部に設置した距離センサ2Bの測定値の
差をもって測定される。これにより、鋳片Ｓからの熱影
響を少なくして且つ非破壊状態でバルジング量を測定す
ることができる。As shown in FIG. 1, the bulging amount of the slab is measured by measuring the central portion and the end portion of the slab S between the rolls 1, 1, --- drawn by the slab guide roll 1. Laser sensors or eddy current type distance sensors 2A and 2B are installed at predetermined intervals, and the difference between the measured values of distance sensor 2A installed at the center of slab S and distance sensor 2B installed at the end. Is measured with. Thereby, the bulging amount can be measured in a non-destructive state while reducing the thermal influence from the slab S.

【００１２】一方、溶鋼の注入温度、鋳型・鋳片案内ロ
ール・スプレー・輻射による放熱を境界条件とし、鋳造
される鋳片Ｓの伝熱凝固計算を実施し、鋳片内部の温度
分布、凝固の進展を見積もる。さらに、この結果を用い
凝固シェルの溶鋼静圧によるロール１，１，------間で
の変形量（バルジング量）をクリープ理論に基づき求め
る。On the other hand, the heat transfer solidification calculation of the cast slab S to be cast is carried out under the boundary conditions of the injection temperature of the molten steel and the heat dissipation by the mold / cast slab guide roll / spray / radiation. Estimate progress. Furthermore, using this result, the amount of deformation (bulging amount) between rolls 1, 1, --- due to the molten steel static pressure of the solidified shell is determined based on the creep theory.

【００１３】上記で測定および計算により求めたバルジ
ング量を比較する。図２は両者のバルジング量を比較し
て示す図で、図から分かるように計算結果と測定結果の
間に明確なずれが、Ｘ点より生じており、この部位が固
相率がほぼ0.3前後の凝固開始位置であり、そして凝固
静圧の無くなるＹ点が凝固完了位置であって、この間が
凝固末期部に相当する。このように凝固末期部が正確に
求められる。The bulging amounts obtained by the above measurement and calculation will be compared. Fig. 2 shows a comparison of both bulging amounts. As can be seen from the figure, there is a clear deviation between the calculation result and the measurement result from point X, and the solid fraction of this part is around 0.3. Is the coagulation start position, and the point Y at which the static coagulation pressure disappears is the coagulation completion position, and during this period corresponds to the end coagulation stage. Thus, the final stage of coagulation can be accurately determined.

【００１４】なお、上記測定および計算により求めたバ
ルジング量の比較において、両者の間で、例えば図３に
示すようなずれが発生する場合がある。これは、ノズル
のづまりなど操業上のばらつきにより伝熱凝固計算と測
定結果にずれが発生しているもので、この場合は、再
度、明確な未凝固部位でのバルジング量の測定結果を凝
固計算にフィードバックし凝固計算の境界条件を調節し
て計算し、未凝固部位でのバルジング量の計算と上記実
測値とを一致させて、比較するとよい。Incidentally, in the comparison of the bulging amounts obtained by the above measurement and calculation, there may be a difference between the two, for example, as shown in FIG. This is because there is a gap between the heat transfer solidification calculation and the measurement result due to operational variations such as nozzle clogging.In this case, the solidification calculation of the clear measurement result of the bulging amount at the unsolidified portion is performed again. It is advisable to adjust the boundary conditions of the coagulation calculation by calculating the bulging amount at the non-coagulated portion and to compare the measured value with the measured value.

【００１５】[0015]

【実施例】以下、本発明の実施例について説明する。60
0mm幅× 380mm厚さのブルームを鋳造速度0.6m／min で
連続鋳造し、凝固末期部で圧下テストを実施し内部品質
の改善効果の確認を行った。EXAMPLES Examples of the present invention will be described below. 60
Bloom of 0 mm width x 380 mm thickness was continuously cast at a casting speed of 0.6 m / min, and a reduction test was conducted at the final stage of solidification to confirm the effect of improving internal quality.

【００１６】この時、上述した図１に示す要領で、鋳片
案内ロール１によって引抜かれるロール１，１，------
間の鋳片Ｓの中央部と端部のそれぞれに所定間隔を開け
て、レーザ方式による距離センサ2A, 2Bを設置し、鋳片
Ｓの中央部に設置した距離センサ2Aと端部に設置した距
離センサ2Bの測定値の差よりバルジング量を実測する一
方、クリープ理論等に基づく計算により、凝固シェルの
溶鋼静圧によるロール１，１，------間での変形量（バ
ルジング量）を求め、これら実測および計算より、図２
に示す凝固開始位置に当たるＸ点を求めた。At this time, the rolls 1, 1, --- which are pulled out by the slab guide roll 1 in the manner shown in FIG. 1 described above.
The distance sensors 2A and 2B by the laser method are installed at the center and the end of the slab S, respectively, and the distance sensor 2A and the end are installed at the center of the slab S. While measuring the bulging amount from the difference between the measured values of the distance sensor 2B, the deformation amount (bulging amount) between rolls 1, 1, --- due to the molten steel static pressure of the solidified shell is calculated by calculation based on the creep theory. ), And from these actual measurements and calculations,
The X point corresponding to the solidification start position shown in was determined.

【００１７】この後、図２に示すＺ点からＹ点までの間
の各点で圧下を加え、得られた鋳片の圧下による改善効
果を確認した。この結果を図４に示す。図４は、圧下位
置に対する中心偏析度および内部割れの圧下による改善
効果を示す図で、横軸は、計算によるＸ点の位置におけ
るバルジング量を(Bcal)、同位置における実測バルジン
グ量を(Bs)とした場合の（Bcal−Bs）／Bcalにより求め
た比率（％）である。After that, reduction was applied at each point from the Z point to the Y point shown in FIG. 2 to confirm the improvement effect by the reduction of the obtained cast piece. The result is shown in FIG. FIG. 4 is a diagram showing the improvement effect of the center segregation degree and the reduction of internal cracks at the rolling position, and the horizontal axis shows the calculated bulging amount at the position of X point (Bcal) and the measured bulging amount at the same position (Bs). ) Is the ratio (%) obtained from (Bcal−Bs) / Bcal.

【００１８】この図によれば、比率が３０〜６０％の範
囲であれば、中心偏析度および内部割れの圧下による改
善効果が得られるが、この範囲を外れた場合にはその効
果が充分に得られないことが分かる。According to this figure, when the ratio is in the range of 30 to 60%, the improvement effect due to the central segregation degree and the reduction of internal cracks can be obtained, but when it is out of this range, the effect is sufficient. You can see that you cannot get it.

【００１９】このように、レーザ方式による距離センサ
2A, 2Bを用いることにより、バルジング量が正確に実測
でき鋳片の凝固末期部が正確に検出できる。しかも、こ
れにより、鋳造条件（溶鋼過熱度等）が変化したときに
も鋳造速度などの操業因子を変化させることで、凝固末
期部を的確に検出しながらその位置を制御でき、圧下が
的確な範囲で行えるので、偏析，内部割れ共に良好な鋳
片を得ることができる。As described above, the distance sensor using the laser system
By using 2A and 2B, the bulging amount can be accurately measured and the final solidification stage of the cast piece can be accurately detected. Moreover, by changing the operating factors such as the casting speed even when the casting conditions (such as the degree of superheat of molten steel) change, the position can be controlled while accurately detecting the final solidification stage, and the reduction can be performed accurately. Since it can be performed within the range, it is possible to obtain a slab with good segregation and internal cracking.

【００２０】[0020]

【発明の効果】以上説明したように、本発明に係わる連
続鋳造される鋳片の凝固末期部の検出方法によれば、高
温鋳片からの熱影響を少なくして、非破壊状態で凝固末
期部を正確に検出することができる。また、これによ
り、的確な範囲での圧下が行え偏析，内部割れ共に良好
な鋳片を得ることができる。As described above, according to the method for detecting the final solidification stage of continuously cast slabs according to the present invention, the thermal influence from the high temperature slab is reduced and the final solidification stage is achieved in a non-destructive state. The part can be accurately detected. Further, by this, it is possible to carry out the reduction within an appropriate range, and it is possible to obtain a slab with good segregation and internal cracking.

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

【図１】本発明方法に係わる鋳片凝固末期部における連
続鋳造設備の説明図である。FIG. 1 is an explanatory view of continuous casting equipment in a final stage of solidification of a slab according to the method of the present invention.

【図２】本発明方法に係わる測定と計算により求めたバ
ルジング量の比較図である。FIG. 2 is a comparison diagram of the amount of bulging obtained by measurement and calculation according to the method of the present invention.

【図３】本発明方法に係わる測定と計算により求めたバ
ルジング量の比較図である。FIG. 3 is a comparison diagram of the bulging amount obtained by measurement and calculation according to the method of the present invention.

【図４】本発明方法に係わる圧下位置に対する中心偏析
度および内部割れの圧下による改善効果を示す図であ
る。FIG. 4 is a diagram showing the effect of improving the center segregation degree with respect to the rolling position and reducing internal cracks according to the method of the present invention.

【符号の説明】[Explanation of symbols]

１：鋳片案内ロール 2A，2B：距離センサ
Ｓ：鋳片1: Cast guide roll 2A, 2B: Distance sensor
S: Slab

Claims (1)

【特許請求の範囲】 【請求項１】 連続鋳造設備の鋳型からその下方に設け
られた鋳片案内ロール間に引抜かれた鋳片の凝固末期部
を検出する方法であって、鋳片案内ロール間の鋳片のバ
ルジング量を引抜き方向に複数個所で測定し、この測定
により得られたバルジング量と予め計算により求めた同
一個所におけるバルジング量との比較により鋳片の凝固
末期部を検出することを特徴とする連続鋳造される鋳片
の凝固末期部の検出方法。Claim: What is claimed is: 1. A method for detecting a final solidification portion of a cast slab drawn from a mold of a continuous casting facility between slab guide rolls provided below the mold, the slab guide roll Detect the bulging amount of the slab in between in the drawing direction, and detect the final stage of solidification of the slab by comparing the bulging amount obtained by this measurement with the bulging amount obtained at the same place calculated in advance. A method for detecting a final solidification stage of a continuously cast slab.