JP6741044B2 - Method and equipment for detecting slab surface defects and equipment abnormalities in continuous casting machines - Google Patents

Method and equipment for detecting slab surface defects and equipment abnormalities in continuous casting machines Download PDF

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JP6741044B2
JP6741044B2 JP2018134660A JP2018134660A JP6741044B2 JP 6741044 B2 JP6741044 B2 JP 6741044B2 JP 2018134660 A JP2018134660 A JP 2018134660A JP 2018134660 A JP2018134660 A JP 2018134660A JP 6741044 B2 JP6741044 B2 JP 6741044B2
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正人 丸山
正人 丸山
克彰 松岡
克彰 松岡
田中 孝憲
孝憲 田中
山内 崇
崇 山内
秀栄 田中
秀栄 田中
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JFE Steel Corp
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本発明は、連続鋳造機における鋳片表面欠陥及び設備異常の検知方法並びに検知設備に関し、詳しくは、鋼の連続鋳造鋳片の切断面の形状に基づいて鋳片の表面欠陥、及び/または、連続鋳造設備の水冷式の鋳型及び二次冷却帯のうちの少なくとも一方の設備異常を検知する方法並びに設備に関する。 The present invention relates to a slab surface defect and equipment abnormality detection method and detection equipment in a continuous casting machine, specifically, a surface defect of a slab based on the shape of a cut surface of a continuously cast slab of steel, and/or The present invention relates to a method and equipment for detecting an equipment abnormality in at least one of a water-cooled mold and a secondary cooling zone of a continuous casting equipment.

鋼の連続鋳造では、鋳型内に注入された溶鋼は水冷式の鋳型によって冷却(「一次冷却」という)され、鋳型との接触面で溶鋼が凝固して凝固シェル(「凝固層」とも呼ぶ)が生成される。この凝固シェルを外殻とし、内部を未凝固層とする鋳片は、鋳型の下流側に設置された鋳片支持ロールで支持されながら水スプレーや気水スプレーによって冷却(「二次冷却」という)され、鋳型下方に連続的に引き抜かれる。鋳片は、水スプレーや気水スプレーによる冷却によって厚み中心部まで凝固し、その後、ガス切断機などの鋳片切断機によって切断されて、所定長さの鋳片が製造されている。鋳片が二次冷却される範囲を「二次冷却帯」と称している。 In continuous casting of steel, the molten steel injected into the mold is cooled by a water-cooled mold (referred to as "primary cooling"), and the molten steel solidifies at the contact surface with the mold and solidifies the shell (also called "solidified layer"). Is generated. The slab that uses this solidified shell as the outer shell and the inside as an unsolidified layer is cooled by a water spray or steam spray while being supported by a slab support roll installed on the downstream side of the mold (referred to as "secondary cooling"). ) And continuously pulled out below the mold. The slab is solidified to a thickness center by cooling with a water spray or a steam spray, and then cut with a slab cutting machine such as a gas cutting machine to manufacture a slab with a predetermined length. The range in which the slab is secondarily cooled is called a "secondary cooling zone".

鋳型内における冷却が不均一になる、または、水スプレーや気水スプレーによる冷却が不均一になると、鋳片の表面に、縦割れ、横割れ、コーナーカギ割れなどのさまざまな欠陥が発生する。 When the cooling in the mold becomes uneven, or the cooling by water spray or steam spray becomes uneven, various defects such as vertical cracks, lateral cracks, and corner key cracks occur on the surface of the slab.

また、鋳型内における冷却が不均一になると、凝固シェル厚みの厚い部分と薄い部分との熱収縮量に差が生じ、鋳片の断面形状が不均一になったりすることもある。同様に、二次冷却帯の設備異常などによって鋳片に冷却水が噴霧されなくなると、冷却水が噴霧されないまたは不足する部分は、抜熱が不足して凝固シェルの表面温度が高くなり、溶鋼静圧によって凝固シェルが外側に膨らみ(外側に膨らむことを「バルジング」という)、鋳片の断面形状が不均一になったりすることもある。 Further, if the cooling in the mold becomes non-uniform, the amount of heat shrinkage between the thick portion and the thin portion of the solidified shell may differ, and the cross-sectional shape of the slab may become non-uniform. Similarly, when the cooling water is no longer sprayed on the slab due to an abnormality in the secondary cooling zone, the surface temperature of the solidified shell becomes high due to insufficient heat removal at the part where the cooling water is not sprayed or insufficient, and the molten steel Static pressure may cause the solidified shell to bulge outward (expanding outward is referred to as "bulging"), and the cross-sectional shape of the slab may become uneven.

鋳片の断面形状が不均一になった場合には、鋳片コーナー部の凝固シェルに内部割れが発生し、この内部割れが凝固界面から凝固シェル表面まで伝播すると、鋳片内部の未凝固層が外部へ流出する、所謂ブリードの発生する危険性がある。ここで、「ブリード」とは、凝固シェルに凝固界面から凝固シェル表面に至る亀裂が生じ、この亀裂から鋳片内部の未凝固層が少量漏れ出す現象である。ブリードが拡大すれば、ブレークアウトに至る。ブリードが生じた鋳片部位は、通常、鋳片表面が二重肌状の表面欠陥になる。 When the cross-sectional shape of the slab becomes uneven, internal cracks occur in the solidified shell at the corner of the slab, and when this internal crack propagates from the solidification interface to the surface of the solidified shell, the unsolidified layer inside the slab There is a risk that so-called bleeding will occur, which means that water will flow out. Here, "bleeding" is a phenomenon in which a crack from the solidification interface to the surface of the solidified shell occurs in the solidified shell, and a small amount of the unsolidified layer inside the slab leaks out from the crack. If the bleed expands, it will lead to a breakout. In the slab portion where bleeding occurs, the surface of the slab usually has double skin-like surface defects.

鋳片表面に存在する欠陥は、次工程の熱間圧延工程で鋼製品の表面欠陥となることから、鋳造後の鋳片の段階において、鋳片の表面を手入れして表面欠陥を除去することが必要となる。 Since defects existing on the surface of the slab become surface defects of the steel product in the next hot rolling step, at the stage of the slab after casting, the surface of the slab should be maintained to remove the surface defects. Is required.

基本的には、このような表面欠陥発生の原因を取り除くことが重要ではあるが、予測し得ない原因によって不測に表面欠陥が発生してしまった鋳片を、他の健全な鋳片と区別して適切な処理を施すことも、実操業においては大切な事項である。つまり、熱間圧延後の鋼製品において欠陥となる鋳片の表面欠陥については、その表面欠陥を有する鋳片を識別・分離してスカーフィングやグラインダー研削などによって表面手入れを施し、表面欠陥を除去した後に熱間圧延に供することが重要である。 Basically, it is important to eliminate the cause of such surface defects, but a slab that has unexpected surface defects due to an unpredictable cause is separated from other sound slabs. Appropriate treatment separately is also an important item in actual operation. In other words, regarding the surface defects of the slab that become defects in the steel product after hot rolling, the slab with the surface defect is identified and separated, and the surface defects are removed by scarfing or grinder grinding. After that, it is important to subject it to hot rolling.

そこで、鋳造中または鋳造直後の鋳片の表面欠陥を、光学式撮影装置や放射温度計を用いてオンラインで検知するまたは予測する技術が多数提案されている。 Therefore, many techniques have been proposed for detecting or predicting the surface defect of the slab during casting or immediately after casting online by using an optical imaging device or a radiation thermometer.

例えば、特許文献1には、連続鋳造機での機内停止により生じた鋳片の表面温度を赤外線カメラで測定し、測定される鋳片の表面温度が予め設定した目標温度よりも低く、且つ、表面温度の低い部位が鋳造方向の所定長さに達したときに、鋳片表面に欠陥が発生したと判定し、且つ、鋳片に表面温度の低い部位が生じる原因となった二次冷却帯の部位を特定し、特定した二次冷却帯の部位に設備異常が発生したと判定する異常検知方法が提案されている。 For example, in Patent Document 1, the surface temperature of the slab generated by the in-machine stop in the continuous casting machine is measured by an infrared camera, the surface temperature of the slab to be measured is lower than a preset target temperature, and, A secondary cooling zone that determines that a defect has occurred on the surface of the slab when the part with a low surface temperature reaches a predetermined length in the casting direction, and that the slab has a part with a low surface temperature. An abnormality detection method has been proposed in which the location is identified and an equipment abnormality is determined to have occurred in the identified area of the secondary cooling zone.

特許文献2には、鋳片表面の熱画像を赤外線カメラで撮影し、熱画像における温度プロファイルに基づき、過去の熱画像における温度プロファイルと鋳片表面の欠陥との対応関係を参照して鋳片表面の欠陥を検知する欠陥検知方法が提案されている。 In Patent Document 2, a thermal image of the surface of the slab is photographed by an infrared camera, and based on the temperature profile in the thermal image, the slab is referenced with reference to the correspondence between the temperature profile in the past thermal image and the defect on the surface of the slab. Defect detection methods for detecting surface defects have been proposed.

特許文献3には、連続鋳造設備の機端から排出されつつある鋳片を、側方及び上方に設けた撮像装置によって撮影し、側方から撮影された鋳片画像を画像処理して鋳片の厚みを測定し、上方から撮影された鋳片画像を画像処理して鋳片の幅を測定する、連続鋳造鋳片の寸法測定方法が提案されている。 In Patent Document 3, a cast piece being discharged from a machine end of a continuous casting facility is photographed by imaging devices provided on the side and the upper side, and a cast piece image photographed from the side is subjected to image processing to obtain a cast piece. Has been proposed, in which the thickness of the slab is measured, and the slab image photographed from above is image-processed to measure the width of the slab.

特許文献4には、ガス切断機によって切断された鋳片の斜め下方より、鋳片切断面から鋳片下面にかけて十字状スリットレーザー光を照射し、十字状スリットレーザー光が照射された鋳片の切断面及び下面をカメラによって撮影し、得られた画像を処理し、鋳片切断面での段差の有無及び鋳片下面への溶断屑(バリ)の付着の有無を検知する、鋳片の切断面形状検知方法が提案されている。 In Patent Document 4, from a diagonally lower side of a cast piece cut by a gas cutting machine, a cross-shaped slit laser beam is irradiated from a cut surface of the cast piece to a lower surface of the cast piece, and the cast piece irradiated with the cross-shaped slit laser light Cutting of the slab, which captures the cut surface and the bottom surface with a camera, processes the obtained images, and detects the presence of steps on the slab cutting surface and the presence of fusing chips (burrs) on the bottom surface of the slab A surface shape detection method has been proposed.

また、鋳片の表面欠陥を検知する技術ではないが、特許文献5には、連続鋳造設備の出側に設けられた鋳片切断機により切断された鋳片の断面温度を二次元放射温度計により測定し、測定した断面温度に基づいて鋳片の最終凝固位置を推定する最終凝固位置推定方法が提案されている。 In addition, although it is not a technique for detecting surface defects of a cast piece, Patent Document 5 discloses a two-dimensional radiation thermometer for measuring the cross-sectional temperature of a cast piece cut by a cast piece cutting machine provided on the outlet side of a continuous casting facility. The method for estimating the final solidification position of the slab based on the measured cross-section temperature is proposed.

特開2014−217849号公報JP, 2014-217849, A 特開2009−66602号公報JP, 2009-66602, A 特開2003−260551号公報JP, 2003-260551, A 特開平11−291008号公報JP, 11-291008, A 特開2014−233734号公報JP, 2014-233734, A

特許文献1及び特許文献2などにより、鋳片の表面割れを主体とする表面欠陥の検知が可能となり、鋳片の表面割れを原因とする鋼製品の表面欠陥は大幅に軽減されている。また、特許文献3により鋳片のバルジング量の経時変化が測定でき、二次冷却帯の設備異常の迅速な検知が可能になって、二次冷却帯の異常に起因する表面欠陥も軽減されている。更に、特許文献4などにより、鋳片の切断面に付着した溶断屑による鋼製品の表面欠陥も大幅に軽減されている。 According to Patent Document 1 and Patent Document 2, it is possible to detect surface defects mainly due to surface cracks in the slab, and the surface defects in the steel product caused by the surface cracks in the slab are greatly reduced. Further, according to Patent Document 3, it is possible to measure the change with time of the bulging amount of the slab, it is possible to quickly detect the equipment abnormality in the secondary cooling zone, and the surface defects caused by the abnormality in the secondary cooling zone are also reduced. There is. Further, according to Patent Document 4 and the like, surface defects of the steel product due to fusing chips adhering to the cut surface of the slab are significantly reduced.

しかしながら、ブリードに起因する鋳片表面欠陥は、特許文献1や特許文献2などで検査対象とする鋳片の長辺面及び短辺面の撮影画像からは検知が難しく、健全な鋳片として次工程の熱間圧延工程に搬出され、鋼製品で表面欠陥が発生する場合が起こる。これは、ブリードは主に水冷式の鋳型内または鋳型直下の二次冷却帯で起こり、光学式撮影装置による検査時点には、ブリード発生箇所の温度は、健全な箇所と同等の温度になってしまい、ブリードが検知できなくなることによる。 However, the slab surface defect caused by the bleeding is difficult to detect from the captured images of the long side surface and the short side surface of the slab to be inspected in Patent Document 1 or Patent Document 2, and the like When the steel product is transported to the hot rolling process of the process, surface defects may occur in the steel product. This is because the bleed mainly occurs in the water-cooled mold or in the secondary cooling zone immediately below the mold.At the time of the inspection by the optical imaging device, the temperature of the bleed occurrence point becomes the same temperature as the sound point. This is because the bleed cannot be detected.

特許文献3は、鋳片のバルジングを測定する技術であり、鋳片に閾値を超える量のバルジングの発生が観察されなくてもブリードが発生することがあり、したがって、特許文献3では、ブリードに起因する鋳片表面欠陥を見逃す可能性がある。 Patent Document 3 is a technique for measuring the bulging of a slab, and bleeding may occur even if the occurrence of bulging in an amount exceeding the threshold value is not observed in the slab. Therefore, in Patent Document 3, the bleeding occurs. There is a possibility of overlooking the slab surface defect caused by it.

後述するように、本発明は鋳片の切断面(横断面)に基づいて鋳片表面欠陥を検知しており、特許文献4及び特許文献5も、鋳片の切断面(横断面)を検査対象としている。しかしながら、特許文献4は、鋳片切断面での段差の有無を検知する技術であり、特許文献5は、断面温度に基づいて鋳片の最終凝固位置を推定する技術であり、いずれもブリードに起因する鋳片表面欠陥については何ら言及していない。 As described later, the present invention detects a slab surface defect based on the slab cut surface (cross section), and Patent Documents 4 and 5 also inspect the slab cut surface (cross section). Intended. However, Patent Document 4 is a technique for detecting the presence/absence of a step on the cut surface of the slab, and Patent Document 5 is a technique for estimating the final solidification position of the slab based on the cross-sectional temperature. No mention is made of the cast slab surface defects.

本発明は上記事情に鑑みてなされたもので、その目的とするところは、鋼の連続鋳造工程において、主にブリードに起因する鋳片表面欠陥を精度良く検知することができ、及び/または、ブリードに起因する鋳片表面欠陥の発生原因となる連続鋳造設備の鋳型または二次冷却帯の設備異常を検知することのできる、連続鋳造機における鋳片表面欠陥及び設備異常の検知方法並びに検知設備を提供することである。 The present invention has been made in view of the above circumstances, and an object thereof is to continuously detect a slab surface defect caused mainly by bleed with high accuracy in a continuous casting process of steel, and/or Detecting method and equipment for detecting slab surface defects and equipment abnormalities in continuous casting machines capable of detecting equipment abnormalities in the mold or secondary cooling zone of continuous casting equipment that causes slab surface defects due to bleeding Is to provide.

本発明者らは、上記課題を解決するべく、鋭意、実験及び研究を行った。その結果、ブリードは、鋳型内または鋳型直下の二次冷却帯での凝固シェルのバルジングや抜熱の不均一に起因して発生し、且つ、バルジング量が大きくなるほど発生することから、連続鋳造中の鋳片の横断面形状の変形量を監視することによってブリードに起因する鋳片表面欠陥を検知できると考え、鋳片横断面形状の経時変化に着目した。 The present inventors have earnestly conducted experiments and researches to solve the above problems. As a result, bleeding occurs due to uneven bulging or heat removal of the solidification shell in the secondary cooling zone in the mold or immediately below the mold, and as the bulging amount increases, it occurs during continuous casting. We considered that it is possible to detect the slab surface defect caused by bleeding by monitoring the amount of deformation of the slab's cross-sectional shape, and focused on the temporal change of the slab's cross-sectional shape.

鋳片横断面形状の経時変化を観察した結果、鋳片毎の横断面形状を時系列で比較し、鋳片長辺面や鋳片短辺面のバルジング及び鋳片短辺面の凹みを早期に認識することで、ブリードに起因する鋳片表面欠陥を検知でき、且つ、ブリードの原因となる鋳型または二次冷却帯の設備異常を検知できることを知見した。 As a result of observing the temporal change of the cross-sectional shape of the slab, the cross-sectional shapes of each slab are compared in time series, and the bulging of the long side surface of the slab and the short side surface of the slab and the depression of the short side surface of the slab are promptly confirmed. By recognizing, it has been found that the slab surface defect caused by the bleed can be detected, and the equipment abnormality of the mold or the secondary cooling zone that causes the bleed can be detected.

本発明は上記知見に基づきなされたものであり、その要旨は以下のとおりである。
[1]連続鋳造機の出側に設けられた鋳片切断機で切断された鋳片の横断面を光学式撮影装置によって撮影し、撮影された画像から鋳片横断面の断面形状を求め、求めた断面形状に基づいて、鋳片の表面欠陥、及び/または、連続鋳造機の鋳型及び二次冷却帯のうちの少なくとも一方の設備異常を検知することを特徴とする、連続鋳造機における鋳片表面欠陥及び設備異常の検知方法。
[2]前記断面形状を、鋳片長辺面のバルジング量または鋳片短辺面の凹み量によって求めることを特徴とする、上記[1]に記載の連続鋳造機における鋳片表面欠陥及び設備異常の検知方法。
[3]前記断面形状の経時変化に基づいて、鋳片の表面欠陥、及び/または、連続鋳造機の鋳型及び二次冷却帯のうちの少なくとも一方の設備異常を検知することを特徴とする、上記[1]または上記[2]に記載の連続鋳造機における鋳片表面欠陥及び設備異常の検知方法。
[4]前記断面形状において、前記鋳片の長辺面に閾値を超える量のバルジングの発生が確認された場合、閾値を超えるバルジングの発生位置を冷却している鋳型の部位及び鋳型直下の二次冷却帯の部位のうちの少なくとも一方の部位で、設備異常が発生していると判定することを特徴とする、上記[1]ないし上記[3]のいずれかに記載の連続鋳造機における鋳片表面欠陥及び設備異常の検知方法。
[5]前記断面形状において、前記鋳片の短辺面に閾値を超える量の凹みの発生が確認された場合、閾値を超える凹みの発生位置を冷却している鋳型の部位及び鋳型直下の二次冷却帯の部位のうちの少なくとも一方の部位で、設備異常が発生していると判定することを特徴とする、上記[1]ないし上記[3]のいずれかに記載の連続鋳造機における鋳片表面欠陥及び設備異常の検知方法。
[6]連続鋳造機の出側に設けられた鋳片切断機で切断された鋳片の横断面を撮影する光学式撮影装置と、前記光学式撮影装置で撮影された画像を記憶する記憶装置と、前記記憶装置に記憶されている画像から鋳片横断面の断面形状を求め、求めた断面形状に基づいて、鋳片の表面欠陥、及び/または、連続鋳造機の二次冷却帯の設備異常を判定する演算表示装置と、を有することを特徴とする、連続鋳造機における鋳片表面欠陥及び設備異常の検知設備。
The present invention has been made based on the above findings, and the summary thereof is as follows.
[1] A cross section of a cast piece cut by a cast piece cutting machine provided on the exit side of the continuous casting machine is photographed by an optical photographing device, and a cross-sectional shape of the cross section of the billet is obtained from the photographed image, Based on the obtained cross-sectional shape, surface defects of the slab, and/or the equipment abnormality of at least one of the mold and the secondary cooling zone of the continuous casting machine is detected, casting in the continuous casting machine One-side surface defect and equipment abnormality detection method.
[2] The slab surface defect and equipment abnormality in the continuous casting machine according to the above [1], wherein the cross-sectional shape is obtained by the bulging amount of the slab long side surface or the dent amount of the slab short side surface. Detection method.
[3] A surface defect of the slab and/or an equipment abnormality of at least one of a mold of a continuous casting machine and a secondary cooling zone is detected based on a change with time of the cross-sectional shape. A method for detecting a slab surface defect and equipment abnormality in the continuous casting machine according to [1] or [2] above.
[4] In the cross-sectional shape, when the occurrence of bulging in an amount exceeding a threshold value is confirmed on the long side surface of the cast slab, the position of the mold that cools the bulging occurrence position exceeding the threshold value and the two immediately below the mold. Casting in the continuous casting machine according to any one of the above [1] to [3], characterized in that it is determined that an equipment abnormality has occurred in at least one of the parts of the next cooling zone. One-side surface defect and equipment abnormality detection method.
[5] In the cross-sectional shape, when it is confirmed that the amount of dents exceeding the threshold value is generated on the short side surface of the cast slab, the position of the dents exceeding the threshold value is being cooled, and two parts are directly under the mold. Casting in the continuous casting machine according to any one of the above [1] to [3], characterized in that it is determined that an equipment abnormality has occurred in at least one of the parts of the next cooling zone. One-side surface defect and equipment abnormality detection method.
[6] An optical photographing device for photographing a cross section of a slab cut by a slab cutting machine provided on the exit side of the continuous casting machine, and a storage device for storing an image photographed by the optical photographing device And a cross-sectional shape of the cross-section of the slab from the image stored in the storage device, and based on the obtained cross-sectional shape, surface defects of the slab and/or equipment of the secondary cooling zone of the continuous casting machine A facility for detecting a slab surface defect and a facility abnormality in a continuous casting machine, comprising: a calculation display device for determining a malfunction.

本発明によれば、バルジングや抜熱の不均一を原因とするブリードに起因する鋳片表面欠陥を、鋳片横断面の断面形状に基づいて検知するので、ブリードの発生に至るようなバルジング量が大きい場合、または、ブリードの発生に至るような鋳片短辺面の凹み量が大きい場合には、凝固完了後の鋳片の横断面の変形量が大きく、したがって、ブリードに起因する鋳片表面欠陥を精度良く検知することが可能となる。また、ブリードに起因する鋳片表面欠陥を精度良く検知することができるので、ブリードの原因となるバルジングや抜熱の不均一を鋳片に生じさせる鋳型または鋳型直下の二次冷却帯の設備異常も検知することが可能となる。 According to the present invention, the slab surface defect caused by the bleeding caused by the nonuniformity of bulging and heat removal is detected based on the cross-sectional shape of the slab transverse cross section, so the bulging amount leading to the occurrence of bleeding. Is large, or when the amount of dent on the short side surface of the slab that causes bleeding is large, the amount of deformation of the cross section of the slab after completion of solidification is large, and therefore the slab resulting from bleeding is large. It becomes possible to detect surface defects with high accuracy. In addition, since it is possible to accurately detect the slab surface defect caused by bleeding, the equipment abnormality of the mold or the secondary cooling zone immediately below the mold that causes bulging that causes bleeding and uneven heat removal in the slab. Can also be detected.

本発明に係る鋳片表面欠陥及び設備異常の検知設備を備えた垂直曲げ型の連続鋳造機の概略側面図である。1 is a schematic side view of a vertical bending type continuous casting machine equipped with a slab surface defect and equipment abnormality detection equipment according to the present invention.

以下、添付図面を参照して本発明を具体的に説明する。図1は、本発明に係る鋳片表面欠陥及び設備異常の検知設備を備えた垂直曲げ型の連続鋳造機の概略側面図である。 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic side view of a vertical bending type continuous casting machine equipped with a slab surface defect and equipment abnormality detection equipment according to the present invention.

図1に示すように、鋳片15(スラブ鋳片)を鋳造するための連続鋳造機1には、溶鋼14を注入して凝固させるための水冷式の鋳型5が設置されており、この鋳型5の上方には、取鍋(図示せず)から溶鋼14を受け、受けた溶鋼14を、浸漬ノズル4を介して鋳型5に供給するタンディッシュ2が配置されている。タンディッシュ2と浸漬ノズル4との間にはタンディッシュ2から鋳型5への溶鋼注入流量を制御するためのスライディングノズル3が設置されている。 As shown in FIG. 1, a continuous casting machine 1 for casting a slab 15 (a slab slab) is provided with a water-cooled mold 5 for injecting and solidifying the molten steel 14, and this mold is used. A tundish 2 that receives the molten steel 14 from a ladle (not shown) and supplies the received molten steel 14 to the mold 5 through the immersion nozzle 4 is arranged above the reference numeral 5. A sliding nozzle 3 for controlling a molten steel injection flow rate from the tundish 2 to the mold 5 is installed between the tundish 2 and the immersion nozzle 4.

一方、鋳型5の下方には、対向する一対のロールを1組とする複数組の鋳片支持ロール6が設置されており、鋳型5から引き抜かれた鋳片15はその上面及び下面を鋳片支持ロール6で支持されながら鋳型5の下方に引き抜かれるようになっている。鋳片支持ロール6の下流側には、つまり、連続鋳造機1の出側には、鋳造された鋳片15を払い出すための複数本の搬送ロール7が設置されている。そして、搬送ロール7の上方には、鋳片引き抜き速度と同期して移動しながら、鋳造されつつある鋳片15を所定長さのスラブ鋳片15a(以下、切断された所定長さのスラブ鋳片を「切断鋳片15a」と記す)に切断するための鋳片切断機19が設置されている。通常、鋳片切断機19としては、鋳片15の幅方向で鋳片15の幅中心部に向かって逆方向に移動しながら鋳片15を溶断する、2つのガストーチを有するガス切断機が使用されている。 On the other hand, below the mold 5, a plurality of sets of slab support rolls 6 each including a pair of facing rolls are installed, and the slab 15 pulled out from the mold 5 has slabs on its upper and lower surfaces. It is adapted to be pulled out below the mold 5 while being supported by the support roll 6. On the downstream side of the slab support roll 6, that is, on the delivery side of the continuous casting machine 1, a plurality of transport rolls 7 for delivering the cast slab 15 are installed. Then, the casting slab 15 being cast is moved above the transport roll 7 in synchronism with the slab withdrawing speed to form a slab casting 15a (hereinafter, cut slab casting of a predetermined length). A cast piece cutting machine 19 for cutting the piece into "cut pieces 15a" is installed. Generally, as the slab cutting machine 19, a gas cutting machine having two gas torches is used which melts and cuts the slab 15 while moving in the opposite direction toward the width center of the slab 15 in the width direction of the slab 15. Has been done.

鋳片支持ロール6が設置された範囲には、鋳型5の直下から下流側に向かって、第1冷却ゾーン8、8、第2冷却ゾーン9、9、第3冷却ゾーン10、10、第4冷却ゾーン11、11、第5冷却ゾーン12、12、及び第6冷却ゾーン13、13の合計12箇所に分割された二次冷却ゾーンからなる二次冷却帯が設置されている。二次冷却帯の各二次冷却ゾーンには、鋳造方向に隣り合う鋳片支持ロール6の間に、水スプレーノズルまたは気水(エアーミスト)スプレーノズルなどのスプレーノズル(図示せず)が設けられ、鋳片15の表面に向けて二次冷却水が噴霧される、または、二次冷却水が空気とともに噴霧されるように構成されている。尚、図1では、二次冷却帯の二次冷却ゾーンの設置数が合計12であるが、連続鋳造機1の設備長さなどに応じて幾つに分割しても構わない。 In the range where the slab support roll 6 is installed, the first cooling zones 8 and 8, the second cooling zones 9 and 9, the third cooling zones 10 and 10, and the fourth cooling zone are provided from directly below the mold 5 toward the downstream side. A secondary cooling zone composed of a secondary cooling zone divided into a total of 12 places of the cooling zones 11, 11, the fifth cooling zones 12, 12, and the sixth cooling zones 13, 13 is installed. In each secondary cooling zone of the secondary cooling zone, a spray nozzle (not shown) such as a water spray nozzle or a water mist spray nozzle is provided between the slab support rolls 6 adjacent in the casting direction. The secondary cooling water is sprayed toward the surface of the slab 15, or the secondary cooling water is sprayed together with air. In FIG. 1, the total number of the secondary cooling zones of the secondary cooling zone is 12, but it may be divided into any number depending on the equipment length of the continuous casting machine 1.

鋳片切断機19によって切断された切断鋳片15aの切断面15sと相対する位置に、CCDカメラや赤外線カメラなどの光学式撮影装置20が設置されており、切断鋳片15aの切断面15s(鋳片15の横断面)が光学式撮影装置20によって撮影されるように構成されている。光学式撮影装置20による撮影時の切断面15sの表面温度は、どの程度であっても問題ない。この場合、光学式撮影装置20は、切断鋳片15aの切断面15sの全体が撮影できるように構成されている。 An optical imaging device 20, such as a CCD camera or an infrared camera, is installed at a position facing the cutting surface 15s of the cutting slab 15a cut by the slab cutting machine 19, and the cutting surface 15s of the cutting slab 15a ( The slab 15 is configured to be photographed by the optical photographing device 20. There is no problem with the surface temperature of the cut surface 15s at the time of photographing by the optical photographing device 20. In this case, the optical imaging device 20 is configured so that the entire cut surface 15s of the cut slab 15a can be imaged.

尚、光学式撮影装置20は、必要に応じて冷却水や冷風で冷却されるようになっている。また、光学式撮影装置20が切断鋳片15aの切断面15sと相対しており、切断面15sを撮影した後の切断鋳片15aを光学式撮影装置20の方向に移動すれば、切断鋳片15aと光学式撮影装置20とが衝突することになるが、切断鋳片15aの搬送方向を、光学式撮影装置20の設置位置の直前で鋳片15の鋳造方向と直交する方向に変えることで、切断鋳片15aと光学式撮影装置20との衝突は回避できる。また、光学式撮影装置20を切断鋳片15aの搬送方向の斜め上方または斜め下方とすることでも、切断鋳片15aと光学式撮影装置20との衝突は回避できる。但し、光学式撮影装置20は切断鋳片15aの切断面15sの形状(横断面形状)を正確に撮影するための装置であり、そのためには、光学式撮影装置20を、切断鋳片15aの切断面15sと相対する位置、つまり、切断面15sと垂直に対向する位置に設置することが好ましい。 The optical imaging device 20 is cooled with cooling water or cold air as needed. Further, the optical imaging device 20 faces the cutting surface 15s of the cutting slab 15a, and if the cutting slab 15a after photographing the cutting surface 15s is moved in the direction of the optical imaging device 20, the cutting slab is cut. 15a and the optical imaging device 20 collide, but by changing the conveying direction of the cutting slab 15a to a direction orthogonal to the casting direction of the slab 15 immediately before the installation position of the optical imaging device 20. The collision between the cutting slab 15a and the optical imaging device 20 can be avoided. Further, the collision between the cutting slab 15a and the optical photographic device 20 can be avoided by setting the optical photographic device 20 obliquely above or below the conveying direction of the cutting slab 15a. However, the optical photographing device 20 is a device for accurately photographing the shape (transverse cross-sectional shape) of the cutting surface 15s of the cutting slab 15a, and for that purpose, the optical photographing device 20 is It is preferable to install it at a position facing the cutting surface 15s, that is, at a position vertically facing the cutting surface 15s.

光学式撮影装置20で撮影された画像はデジタル処理され、デジタル処理された画像データは、光学式撮影装置20から記憶装置21に送信されて、記憶装置21で記憶される。記憶する画像データには、溶鋼14のチャージ番号、鋼種、鋳片の寸法、ストランド番号、鋳造日時などのデータも合わせて記憶する。 The image captured by the optical imaging device 20 is digitally processed, and the digitally processed image data is transmitted from the optical imaging device 20 to the storage device 21 and stored in the storage device 21. The stored image data also stores data such as charge number of molten steel 14, steel type, slab size, strand number, casting date and time.

また、記憶装置21に記憶された画像データは演算表示装置22に送信される。演算表示装置22は、入力された画像データから切断鋳片15aの切断面15sの断面形状を求め、求めた断面形状に基づいて、鋳片15の表面欠陥、及び/または、連続鋳造機1の鋳型5または鋳型直下の二次冷却帯の設備異常を判定する。 Further, the image data stored in the storage device 21 is transmitted to the calculation display device 22. The calculation display device 22 obtains the cross-sectional shape of the cut surface 15s of the cut slab 15a from the input image data, and based on the obtained cross-sectional shape, the surface defect of the slab 15 and/or the continuous casting machine 1 The equipment abnormality of the mold 5 or the secondary cooling zone immediately below the mold is determined.

求めた断面形状に基づいて、鋳片15の表面欠陥、及び/または、連続鋳造機1の鋳型5または鋳型直下の二次冷却帯の設備異常を判定するにあたり、予め設定した断面形状の閾値と、その時点で把握した断面形状とを比較して、得られた断面形状が閾値を超えたときに表面欠陥及び/または設備異常が発生したと判定することができ、また、断面形状の経時変化に基づいて表面欠陥及び/または設備異常が発生したと判定することもできる。 Based on the obtained cross-sectional shape, in determining the surface defect of the cast piece 15 and/or the equipment abnormality of the mold 5 of the continuous casting machine 1 or the secondary cooling zone immediately below the mold, a threshold value of the cross-sectional shape set in advance , It is possible to determine that a surface defect and/or equipment abnormality has occurred when the obtained cross-sectional shape exceeds the threshold value by comparing it with the cross-sectional shape obtained at that time. It is also possible to determine that a surface defect and/or equipment abnormality has occurred based on the above.

本発明で対象とする、厚みが150〜350mmで、幅が950〜3000mmの横断面を有するスラブ鋳片において、操業異常の生じていない鋳片15の横断面形状は、通常、矩形であるか、または、鋳片長辺面は、上面及び下面がほぼ平行で、鋳片短辺面が円弧状に凹んだ形状(凹みの深さ;2〜4mm)となる。この横断面形状に対して、例えば、横断面形状が矩形でなく、鋳片長辺面がバルジングして鋳片幅方向左右の鋳片厚みが異なる(例えば、左右の鋳片厚み差が4mm以上)、または、鋳片短辺面中心部の凹み量が左右で異なり、且つ、一方の凹み量が大きい(例えば5mm以上)などの場合に、閾値を超えたとして、鋳片15にブリードに起因する鋳片表面欠陥が発生したと判定する。 In the slab slab having a cross section of 150 to 350 mm in thickness and 950 to 3000 mm in width, which is the object of the present invention, is the slab 15 in which the operation abnormality does not occur usually have a rectangular cross section? Alternatively, the long side surface of the slab has a shape in which the upper surface and the lower surface are substantially parallel to each other and the short side surface of the slab is recessed in an arc shape (the depth of the recess; 2 to 4 mm). In contrast to this cross-sectional shape, for example, the cross-sectional shape is not rectangular, the long side of the slab is bulging, and the slab thickness on the left and right of the slab width direction is different (for example, the slab thickness difference on the left and right is 4 mm or more). Or, when the dent amount in the central portion of the short side surface of the slab is different between the left and right and one dent amount is large (for example, 5 mm or more), it is considered that the slab 15 is bleeded because the threshold value is exceeded. It is determined that a slab surface defect has occurred.

鋳片短辺面中心部の凹み量がブリードの有無に関係するメカニズムは明確ではないが、鋳片短辺面中心部の凹みは、鋳片支持ロール間などで鋳片長辺面がバルジングする際の歪に起因して生ずると考えられ、その凹みの大きさは鋳片長辺面のバルジング量の程度を反映していると考えられる。つまり、鋳片長辺面のバルジング量が大きくなれば鋳片短辺面中心部の凹み量が大きくなると考えられる。したがって、鋳片長辺面のバルジング量が大きい場合に生じ易いブリードは、同様に、鋳片短辺面中心部の凹み量と関連すると理解できる。尚、鋳片長辺面のバルジングは、バルジングが発生した位置よりも下流側の鋳片支持ロール6の複数対によって矯正され、切断鋳片15aの切断面15sでは、鋳片長辺面のバルジングが観察されないことも起こる。 The mechanism by which the amount of dents in the center of the short side of the slab is related to the presence or absence of bleeding is not clear, but the dent in the center of the short side of the slab does not occur when the long side of the slab bulges between slab support rolls. It is considered that this is caused by the strain of the slab and the size of the dent reflects the degree of bulging on the long side surface of the slab. That is, it is considered that the larger the bulging amount on the long side surface of the slab, the larger the dent amount at the central portion of the short side surface of the slab. Therefore, it can be understood that the bleeding that tends to occur when the bulging amount of the long side of the slab is large is similarly related to the amount of depression of the central portion of the short side of the slab. The bulging on the long side of the slab is corrected by a plurality of pairs of the slab supporting rolls 6 on the downstream side of the position where the bulging occurs, and the bulging on the long side of the slab is observed on the cut surface 15s of the cut slab 15a. Some things are not done.

一方、画像データの経時変化の比較は、同一鋳型5で連続鋳造された鋳片15の断面画像の輪郭を時系列毎に電子的に比較することで行うことができる。比較方法は、特にこの方法に限らないが、例えば、両方の鋳片短辺中央位置同士の距離及び両方の鋳片長辺中央位置の距離を比較する方法がある。鋳片短辺中央位置同士の距離が時間の経過毎に短くなっていれば、鋳片短辺面が凹み形状になっていて、その凹み量が徐々に大きくなっていると判断でき、一方、鋳片長辺中央位置の距離が大きくなっていれば、鋳片長辺面にバルジングが発生し始めていると判断できる。つまり、例えば、鋳片15のバルジング速度や短辺面の凹み速度などを経時的に求め、求めたバルジング速度や凹み速度が或る数値を超えたときに、表面欠陥及び/または設備異常が発生したと判定する。 On the other hand, the temporal change of the image data can be compared by electronically comparing the contours of the cross-sectional images of the ingots 15 continuously cast in the same mold 5 for each time series. The comparison method is not particularly limited to this method, but there is, for example, a method of comparing the distance between the center positions of both short sides of both slabs and the distance between the center positions of both long sides of the slabs. If the distance between the slab short side center positions decreases with the passage of time, it can be determined that the slab short side surface has a concave shape, and the amount of the recess gradually increases, while If the distance between the central positions of the long sides of the slab is large, it can be determined that bulging has started to occur on the long side surface of the slab. That is, for example, the bulging speed of the slab 15 or the dent speed of the short side surface is obtained over time, and when the obtained bulging speed or dent speed exceeds a certain value, a surface defect and/or equipment abnormality occurs. It is judged that it did.

そして、撮影した断面形状が予め設定した所定の形状の範囲を超えた場合や、撮影した断面形状の経時変化から異常が発生したと判定した場合には、演算表示装置22は、切断鋳片15aに表面欠陥が発生したと判定し、且つ、鋳片15の横断面形状が異常となるほどの設備異常が、鋳型5及び鋳型直下の二次冷却帯のうちの少なくとも一方で発生したと判定し、演算表示装置22に異常発生を表示すると同時に、警報機23を介して異常の発生を発報する。 Then, when the photographed cross-sectional shape exceeds the range of the preset predetermined shape, or when it is determined that an abnormality has occurred due to the temporal change of the photographed cross-sectional shape, the calculation display device 22 causes the cutting slab 15a to be cut. It is determined that a surface defect has occurred in the, and equipment abnormality such that the cross-sectional shape of the cast piece 15 is abnormal, it is determined that at least one of the mold 5 and the secondary cooling zone immediately below the mold has occurred, The abnormality display is displayed on the arithmetic and display unit 22, and at the same time, the occurrence of the abnormality is reported via the alarm device 23.

本発明に係る鋳片表面欠陥及び設備異常の検知設備を備えた連続鋳造機1は、このようにして構成されている。このような構成の連続鋳造機1において、以下のようにして本発明に係る検知方法を実施する。 The continuous casting machine 1 including the slab surface defect and equipment abnormality detection equipment according to the present invention is configured in this manner. In the continuous casting machine 1 having such a configuration, the detection method according to the present invention is carried out as follows.

タンディッシュ2から浸漬ノズル4を介して鋳型5に溶鋼14を注入する。鋳型5に注入された溶鋼14は鋳型5で冷却されて鋳型5との接触面に凝固シェル16を形成し、内部に未凝固層17を有する鋳片15として、鋳片支持ロール6に支持されつつピンチロール(鋳片支持ロール6の内の複数組のロール)によって下方に連続的に引抜かれる。鋳片15は鋳片支持ロール6の設置範囲を通過する間、二次冷却帯の各二次冷却ゾーンで冷却され、凝固シェル16の厚みを増大し、やがて、凝固完了位置18で厚み中心部までの凝固を完了する。そして、鋳造した鋳片15を鋳片切断機19により切断して切断鋳片15aを得る。 Molten steel 14 is poured into the mold 5 from the tundish 2 through the immersion nozzle 4. The molten steel 14 poured into the mold 5 is cooled by the mold 5 to form a solidified shell 16 on the contact surface with the mold 5, and is supported by the slab support roll 6 as a slab 15 having an unsolidified layer 17 inside. Meanwhile, it is continuously drawn downward by a pinch roll (a plurality of rolls in the slab supporting roll 6). The slab 15 is cooled in each of the secondary cooling zones of the secondary cooling zone while passing through the installation range of the slab support roll 6, and the thickness of the solidification shell 16 is increased. Complete coagulation until. Then, the cast slab 15 is cut by the slab cutting machine 19 to obtain a cut slab 15a.

切断鋳片15aの切断面15s(鋳片横断面)の断面形状を、鋳片15が切断される毎に光学式撮影装置20で撮影し、画像データを記憶装置21で記憶させる。演算表示装置22は、記憶装置21から入力された画像データから鋳片15の横断面の断面形状を求め、求めた断面形状に基づいて鋳片15の表面欠陥、及び/または、連続鋳造機1の鋳型5または鋳型直下の二次冷却帯の設備異常を判定する。 The cross-sectional shape of the cut surface 15 s (cross section of the slab) of the slab 15 a is photographed by the optical photographing device 20 every time the slab 15 is cut, and the image data is stored in the storage device 21. The arithmetic and display unit 22 obtains the cross-sectional shape of the transverse section of the slab 15 from the image data input from the storage unit 21, and based on the obtained cross-sectional shape, the surface defects of the slab 15 and/or the continuous casting machine 1 The equipment abnormality of the mold 5 or the secondary cooling zone immediately below the mold is determined.

画像データから求められた鋳片15の横断面形状が、矩形でなく且つ鋳片幅方向左右の鋳片厚みが異なる場合には、鋳片15にバルジングが発生し、そのバルジングが凝固完了後も残留したことを意味する。したがって、鋳片15の横断面形状から、鋳片15に予め設定した閾値を超えるバルジングの発生が確認された場合には、鋳片15のバルジング発生位置を冷却している鋳型5の部位及び鋳型直下の二次冷却帯の部位のうちの少なくとも一方の部位に、ブリードに起因する鋳片表面欠陥を発生させるほどの設備異常が発生していると判定できる。 If the cross-sectional shape of the slab 15 obtained from the image data is not rectangular and the slab thicknesses on the left and right in the slab width direction are different, bulging occurs in the slab 15 and even after the solidification is completed. It means that it remains. Therefore, when it is confirmed from the cross-sectional shape of the slab 15 that bulging exceeding the preset threshold value is generated in the slab 15, the bulging occurrence position of the slab 15 and the portion of the mold 5 that is cooling It can be determined that at least one of the sites of the secondary cooling zone immediately below has an equipment abnormality that causes a slab surface defect due to bleeding.

鋳片15のバルジングは、凝固シェル16の厚みが増大した時点、つまり鋳型直下から離れた位置では発生しにくいことから、鋳型直下の二次冷却帯で、且つ、バルジングの発生位置に該当する二次冷却帯で設備異常が発生していると判定できる。ここで、鋳型直下の二次冷却帯とは、鋳型5の下端から3mないし4m程度下流までの範囲の二次冷却ゾーンとすればよい。スラブ鋳片用の連続鋳造機1では、設備長さが40mを超える連続鋳造機もあり、バルジングの原因となる二次冷却帯の設備異常の位置を、鋳型5の下端から3mないし4m程度下流までの範囲に特定することで、二次冷却帯の設備異常の箇所を容易に見つけることが可能となる。 Since bulging of the slab 15 is unlikely to occur at the time when the thickness of the solidified shell 16 is increased, that is, at a position away from directly below the mold, it is a secondary cooling zone immediately below the mold and corresponds to the bulging occurrence position. It can be determined that an equipment abnormality has occurred in the next cooling zone. Here, the secondary cooling zone immediately below the mold may be a secondary cooling zone in the range from the lower end of the mold 5 to the downstream by about 3 m to 4 m. In the continuous casting machine 1 for slab cast, there is also a continuous casting machine having a facility length of more than 40 m, and the position of the facility abnormality in the secondary cooling zone that causes bulging is located about 3 to 4 m downstream from the lower end of the mold 5. By specifying the range up to, it becomes possible to easily find the location of the equipment abnormality in the secondary cooling zone.

同様に、鋳片15の横断面形状において、鋳片15の短辺面に閾値を超える量の凹みの発生が確認された場合には、閾値を超える凹みの発生位置を冷却している鋳型5の部位及び鋳型直下の二次冷却帯の部位のうちの少なくとも一方の部位に、ブリードに起因する鋳片表面欠陥を発生させるほどの設備異常が発生していると判定できる。 Similarly, in the transverse cross-sectional shape of the slab 15, if it is confirmed that the short side surface of the slab 15 has an amount of dents exceeding the threshold value, the mold 5 that cools the position where the dents exceeding the threshold value are generated. It can be determined that an equipment abnormality that causes a slab surface defect due to bleeding has occurred in at least one of the site 2) and the site of the secondary cooling zone immediately below the mold.

鋳片15にブリードに起因する鋳片表面欠陥が発生したと検知された場合には、そのストランドの鋳型5への溶鋼14の注入を停止し、そのストランド内の鋳片15を連続鋳造機1から払い出し、その後、ブリードに起因する鋳片表面欠陥及びその他の表面割れの有無を点検する。表面欠陥が見つかった場合には、スカーフィングやグラインダー研削によって表面欠陥を除去する。鋳片15にブリードに起因する鋳片表面欠陥が発生したと検知された場合は、ブリードに起因する鋳片表面欠陥が発生していないと判定した同一鋳造チャンスの当該ストランドのそれ以前の切断鋳片15aも表面欠陥の詳細なチェックを行うことが好ましい。得られた結果を前記判定の閾値にフィードバックすることが更に好ましい。 When it is detected that the slab surface defect due to the bleeding is generated in the slab 15, the injection of the molten steel 14 into the mold 5 of the strand is stopped, and the slab 15 in the strand is transferred to the continuous casting machine 1 And then inspect for slab surface defects and other surface cracks caused by bleed. If surface defects are found, they are removed by scarfing or grinder grinding. When it is detected that the slab surface defect caused by the bleed is generated in the slab 15, it is determined that the slab surface defect caused by the bleed is not generated, and the cut casting before the strand of the strand having the same casting chance is determined. It is preferable that the piece 15a also be subjected to a detailed surface defect check. It is more preferable to feed back the obtained result to the threshold value of the judgment.

本発明は、主にブリードに起因する鋳片表面欠陥を検知する技術であるが、ブリードが発生するほどのバルジングや抜熱の不均一が鋳片15に起こっている場合には、二次冷却帯での鋳片長辺面の不均一冷却や、鋳片コーナー部の過冷却が起こり易く、これによって、鋳片15に縦割れ、横割れ、コーナーカギ割れが発生するおそれがある。したがって、本発明は、鋳片15の横断面を監視しているが、鋳片表面の縦割れ、横割れ、コーナーカギ割れも検知することができる。 The present invention is mainly a technique for detecting a slab surface defect caused by bleeding. However, when bulging or non-uniform heat removal that causes bleeding occurs in the slab 15, secondary cooling is performed. Non-uniform cooling of the long side surface of the slab in the strip and supercooling of the corner portion of the slab are likely to occur, which may cause vertical cracks, lateral cracks, and corner key cracks in the slab 15. Therefore, although the present invention monitors the cross section of the slab 15, vertical cracks, lateral cracks, and corner key cracks on the surface of the slab can also be detected.

連続鋳造の終了後、鋳片15のバルジング発生位置または鋳片短辺面の凹み発生位置を冷却している鋳型5の部位及び鋳型直下の二次冷却帯の部位の設備異常の有無を点検する。先ず、鋳型5を点検し、次いで、鋳型5の下端から3mないし4m程度下流までの範囲の二次冷却帯を点検し、その範囲で設備異常が見つからない場合は、その下流側の二次冷却帯の点検を続ける。 After the end of continuous casting, the presence or absence of equipment abnormality is inspected in the part of the mold 5 that cools the bulging occurrence position of the slab 15 or the dent occurrence position of the short side surface of the slab and the part of the secondary cooling zone immediately below the mold. .. First, the mold 5 is inspected, then the secondary cooling zone in the range of 3 m to 4 m downstream from the lower end of the mold 5 is inspected, and if no facility abnormality is found in that range, secondary cooling of the downstream side is performed. Continue to check the belt.

以上説明したように、本発明によれば、鋳片15のバルジングや抜熱の不均一を原因とするブリードに起因する鋳片表面欠陥を、鋳片横断面の断面形状に基づいて検知するので、ブリードに起因する鋳片表面欠陥を精度良く検知することが実現される。また、ブリードに起因する鋳片表面欠陥を精度良く検知することができるので、ブリードの原因となるバルジングまたは短辺面の凹みを鋳片15に生じさせる鋳型5または鋳型直下の二次冷却帯の設備異常を検知することも可能となる。また、当然ながら、ブリードに起因する鋳片表面欠陥を有する切断鋳片15aの次工程への搬出が防止される。 As described above, according to the present invention, a slab surface defect caused by bleeding due to bulging of the slab 15 and uneven heat removal is detected based on the cross-sectional shape of the slab cross section. Thus, it is possible to accurately detect the slab surface defect caused by the bleeding. Further, since the slab surface defect caused by the bleed can be detected with high precision, the mold 5 or the secondary cooling zone immediately below the mold 5 which causes the bulge or the short side surface indentation in the slab 15 to cause the bleed. It is also possible to detect equipment abnormalities. In addition, it goes without saying that the cut slab 15a having the slab surface defect caused by the bleeding is prevented from being carried out to the next step.

厚みが220mmで、幅が1900mmの低炭素アルミキルド鋼のスラブ鋳片を、2.0m/minの鋳片引き抜き速度で連続鋳造する垂直曲げ型の2ストランドの連続鋳造機で本発明を実施した。切断されたスラブ鋳片は、連続鋳造機のストランドの中心位置を鋳造方向に搬送され、その後、連続鋳造機のストランドの鋳造方向と直交する方向に排出されるように構成された連続鋳造機である。 The present invention was carried out in a vertical bending type two-strand continuous casting machine for continuously casting a slab cast of a low carbon aluminum killed steel having a thickness of 220 mm and a width of 1900 mm at a cast drawing speed of 2.0 m/min. The cut slab slab is conveyed in the casting direction in the center position of the strand of the continuous casting machine, and then, in a continuous casting machine configured to be discharged in a direction orthogonal to the casting direction of the strand of the continuous casting machine. is there.

光学式撮影装置として空冷式のCCDカメラを使用し、スラブ鋳片の搬送方向が鋳造方向から直交する位置に、2つのストランドの中心位置で、且つ、スラブ鋳片の厚み中心位置に相当する位置に、それぞれ1基のCCDカメラをスラブ鋳片の切断面に相対するように配置した。 An air-cooled CCD camera is used as an optical photographing device, and a position where the transport direction of the slab slab is orthogonal to the casting direction, a position corresponding to the center position of the two strands and a thickness center position of the slab slab On the other hand, one CCD camera was arranged so as to face the cut surface of the slab slab.

CCDカメラで撮影された画像データに基づいてスラブ鋳片横断面の断面形状の経時変化を演算表示装置によって監視した。画像データにおいて、断面形状の閾値として、スラブ鋳片の厚みが通常の場合よりも局所的に4mm以上大きくなったとき、または、スラブ鋳片短辺面の凹みが5mm以上となったときとした。そして、監視される画像データが閾値を超えた場合には、スラブ鋳片にブリードに起因する鋳片表面欠陥が発生したと判定する、鋼の連続鋳造操業を実施した。 Based on the image data taken by the CCD camera, the time-dependent change in the cross-sectional shape of the slab slab cross-section was monitored by the arithmetic display device. In the image data, as the threshold value of the cross-sectional shape, it was determined that the thickness of the slab slab was locally increased by 4 mm or more as compared with the normal case, or the dent of the short side surface of the slab slab was 5 mm or more. .. Then, when the monitored image data exceeded the threshold value, it was determined that a slab surface defect due to bleeding occurred in the slab slab, and a continuous steel casting operation was performed.

連続鋳造操業を続けていく過程で、一方のストランドで、スラブ鋳片短辺面の凹みが5mm以上となった連続鋳造操業が発生した。この場合、スラブ鋳片の局所的な厚みの増加量は、通常の場合に対して2mm以下であった。その連続鋳造操業では、スラブ鋳片短辺面の凹みが5mm以上となったストランドでの連続鋳造を、鋳片表面欠陥が発生したと判定した時点で直ちに停止し、取鍋に残留した溶鋼を他のストランドで連続鋳造し、その後に予定されていたチャージの連々鋳は中止した。 In the process of continuing the continuous casting operation, in one strand, the continuous casting operation in which the dent of the short side surface of the slab slab became 5 mm or more occurred. In this case, the amount of increase in local thickness of the slab slab was 2 mm or less as compared with the usual case. In the continuous casting operation, the continuous casting of the strand in which the short side surface of the slab slab has a recess of 5 mm or more is immediately stopped when it is determined that a slab surface defect has occurred, and the molten steel remaining in the ladle is removed. Continuous casting was performed on the other strands, and then the planned continuous casting of charges was stopped.

当該チャージの連続鋳造の終了後、スラブ鋳片短辺面の凹みが拡大した側の鋳型の部位及び鋳型直下から3mの範囲の二次冷却帯の部位を点検した。その結果、二次冷却帯のスラブ鋳片下面側の気水スプレーノズルが閉塞しており、スラブ鋳片に二次冷却水が噴霧されていない状態であることが確認された。閉塞した気水スプレーノズルを交換したところ、以降の連続鋳造では、スラブ鋳片短辺面の凹みが5mm以上となることは起こらなかった。 After the continuous casting of the charge was completed, the part of the mold on the side where the dent on the short side of the slab slab was enlarged and the part of the secondary cooling zone in the range of 3 m from directly below the mold were inspected. As a result, it was confirmed that the steam spray nozzle on the lower surface side of the slab slab in the secondary cooling zone was blocked, and the slab slab was not sprayed with the secondary cooling water. When the clogged water spray nozzle was replaced, in the subsequent continuous casting, the dent of the short side surface of the slab slab did not become 5 mm or more.

また、スラブ鋳片短辺面の凹みが5mm以上となったストランドで連続鋳造した全てのスラブ鋳片を工程運用から外し、スラブ鋳片の表面検査を実施した。この表面検査の結果、鋳片表面欠陥が発生したと判定した時点のスラブ鋳片には、ブリードに起因する鋳片表面欠陥が認められた。また、鋳片表面欠陥が発生したと判定した時点よりも後に連続鋳造したスラブ鋳片(連続鋳造を停止した時点、つまり、鋳型への溶鋼注入を停止した時点で連続鋳造機内に存在していた鋳片)にも、ブリードに起因する鋳片表面欠陥が認められた。一方、鋳片表面欠陥が発生したと判定した時点よりも前に連続鋳造したスラブ鋳片では、若干のバルジングが鋳片長辺面に認められたものの、ブリードに起因する鋳片表面欠陥は認められなかった。 Further, all the slab slabs continuously cast by the strand having the dent of the short side surface of the slab slab of 5 mm or more were removed from the process operation, and the surface inspection of the slab slab was carried out. As a result of this surface inspection, the slab cast at the time when it was determined that the cast slab surface defects were generated, the cast slab surface defects caused by bleeding were observed. Further, a slab slab continuously cast after the slab surface defect was determined to have occurred (at the time when the continuous casting was stopped, that is, when the molten steel injection into the mold was stopped, the slab was present in the continuous casting machine. In the slab), slab surface defects due to bleeding were also recognized. On the other hand, in the slab slab continuously cast before the time when it was determined that a slab surface defect occurred, some bulging was observed on the long side of the slab, but a slab surface defect due to bleeding was observed. There wasn't.

ブリードに起因する鋳片表面欠陥が認められたスラブ鋳片は、スカーフィングによりブリードに起因する鋳片表面欠陥を除去して工程運用とした。 For the slab slab in which the slab surface defect caused by the bleed was recognized, the slab surface defect caused by the bleed was removed by the scarfing and the process operation was performed.

1 連続鋳造機
2 タンディッシュ
3 スライディングノズル
4 浸漬ノズル
5 鋳型
6 鋳片支持ロール
7 搬送ロール
8 第1冷却ゾーン
9 第2冷却ゾーン
10 第3冷却ゾーン
11 第4冷却ゾーン
12 第5冷却ゾーン
13 第6冷却ゾーン
14 溶鋼
15 鋳片
15a 切断鋳片
15s 切断面
16 凝固シェル
17 未凝固層
18 凝固完了位置
19 鋳片切断機
20 光学式撮影装置
21 記憶装置
22 演算表示装置
23 警報機
DESCRIPTION OF SYMBOLS 1 Continuous casting machine 2 Tundish 3 Sliding nozzle 4 Immersion nozzle 5 Mold 6 Cast strip support roll 7 Conveying roll 8 1st cooling zone 9 2nd cooling zone 10 3rd cooling zone 11 4th cooling zone 12 5th cooling zone 13th 6 Cooling Zone 14 Molten Steel 15 Slab 15a Cutting Slab 15s Cutting Surface 16 Solidified Shell 17 Unsolidified Layer 18 Solidification Completed Position 19 Slab Cutting Machine 20 Optical Imaging Device 21 Storage Device 22 Arithmetic Display Device 23 Alarm

Claims (5)

連続鋳造機の出側に設けられた鋳片切断機で切断された鋳片の横断面を光学式撮影装置によって撮影し、撮影された画像から鋳片横断面の断面形状を、鋳片長辺面のバルジング量または鋳片短辺面の凹み量によって求め、求めた断面形状に基づいて、鋳片長辺面及び鋳片短辺面ブリードに起因する表面欠陥、及び/または、連続鋳造機の鋳型及び二次冷却帯のうちの少なくとも一方の前記表面欠陥の原因となる設備異常を検知することを特徴とする、連続鋳造機における鋳片表面欠陥及び設備異常の検知方法。 The cross section of the cast piece cut by the cast piece cutting machine provided on the exit side of the continuous casting machine is photographed by an optical photographing device, and the cross-sectional shape of the cross section of the cast piece is taken from the photographed image , the long side of the cast piece. The amount of bulging of the cast slab or the amount of dent on the short side of the slab, and based on the obtained cross-sectional shape, surface defects caused by bleeding of the long side of the slab and short side of the slab , and/or A method of detecting a cast slab surface defect and a facility abnormality in a continuous casting machine, which comprises detecting a facility abnormality causing the surface defect in at least one of the mold and the secondary cooling zone. 前記断面形状の経時変化に基づいて、鋳片のブリードに起因する表面欠陥、及び/または、連続鋳造機の鋳型及び二次冷却帯のうちの少なくとも一方の前記表面欠陥の原因となる設備異常を検知することを特徴とする、請求項1に記載の連続鋳造機における鋳片表面欠陥及び設備異常の検知方法。 Based on the change with time of the cross-sectional shape, surface defects caused by bleeding of the slab, and / or, the equipment abnormality that causes the surface defects of at least one of the mold and the secondary cooling zone of the continuous casting machine. The method for detecting a slab surface defect and equipment abnormality in the continuous casting machine according to claim 1, wherein the method is for detecting. 前記断面形状において、前記鋳片の長辺面に閾値を超える量のバルジングの発生が確認された場合、閾値を超えるバルジングの発生位置を冷却している鋳型の部位及び鋳型直下の二次冷却帯の部位のうちの少なくとも一方の部位で、前記表面欠陥の原因となる設備異常が発生していると判定することを特徴とする、請求項1または請求項2に記載の連続鋳造機における鋳片表面欠陥及び設備異常の検知方法。 In the cross-sectional shape, if the occurrence of bulging in an amount exceeding the threshold on the long side surface of the slab is confirmed, the site of the mold that is cooling the occurrence position of bulging exceeding the threshold and the secondary cooling zone immediately below the mold. The cast piece in the continuous casting machine according to claim 1 or 2 , wherein it is determined that an equipment abnormality causing the surface defect has occurred in at least one of the above parts. Surface defect and equipment abnormality detection method. 前記断面形状において、前記鋳片の短辺面に閾値を超える量の凹みの発生が確認された場合、閾値を超える凹みの発生位置を冷却している鋳型の部位及び鋳型直下の二次冷却帯の部位のうちの少なくとも一方の部位で、前記表面欠陥の原因となる設備異常が発生していると判定することを特徴とする、請求項1または請求項2に記載の連続鋳造機における鋳片表面欠陥及び設備異常の検知方法。 In the cross-sectional shape, if the occurrence of dents in an amount exceeding the threshold on the short side surface of the slab is confirmed, the site of the mold that is cooling the occurrence position of the dents exceeding the threshold and the secondary cooling zone immediately below the mold. The cast piece in the continuous casting machine according to claim 1 or 2 , wherein it is determined that an equipment abnormality causing the surface defect has occurred in at least one of the above parts. Surface defect and equipment abnormality detection method. 連続鋳造機の出側に設けられた鋳片切断機で切断された鋳片の横断面を撮影する光学式撮影装置と、
前記光学式撮影装置で撮影された画像を記憶する記憶装置と、
前記記憶装置に記憶されている画像から鋳片横断面の断面形状を、鋳片長辺面のバルジング量または鋳片短辺面の凹み量によって求め、求めた断面形状に基づいて、鋳片長辺面及び鋳片短辺面ブリードに起因する表面欠陥、及び/または、連続鋳造機の鋳型及び二次冷却帯のうちの少なくとも一方前記表面欠陥の原因となる設備異常を判定する演算表示装置と、
を有することを特徴とする、連続鋳造機における鋳片表面欠陥及び設備異常の検知設備。
An optical photographing device for photographing a cross section of a cast piece cut by a cast piece cutting machine provided on the exit side of the continuous casting machine,
A storage device for storing an image taken by the optical imaging device,
The cross-sectional shape of the slab transverse section from the image stored in the storage device is obtained by the amount of bulging of the slab long side surface or the amount of depression of the slab short side surface, and based on the obtained cross-sectional shape, the slab long side Display device for determining an equipment defect that causes surface defects caused by bleeding of the slab surface and the short side surface of the slab , and/or the surface defects of at least one of the mold and the secondary cooling zone of the continuous casting machine When,
A facility for detecting a slab surface defect and a facility abnormality in a continuous casting machine, which comprises:
JP2018134660A 2017-07-20 2018-07-18 Method and equipment for detecting slab surface defects and equipment abnormalities in continuous casting machines Active JP6741044B2 (en)

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