JP6107770B2 - Method and apparatus for detecting transverse cracks in continuous cast slab, and method and apparatus for producing continuous cast slab using the detection method - Google Patents
Method and apparatus for detecting transverse cracks in continuous cast slab, and method and apparatus for producing continuous cast slab using the detection method Download PDFInfo
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- 238000000034 method Methods 0.000 title claims description 33
- 238000001514 detection method Methods 0.000 title claims description 30
- 238000005266 casting Methods 0.000 claims description 47
- 238000005336 cracking Methods 0.000 claims description 25
- 238000006073 displacement reaction Methods 0.000 claims description 15
- 238000012423 maintenance Methods 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 15
- 230000010355 oscillation Effects 0.000 claims description 13
- 238000009749 continuous casting Methods 0.000 claims description 12
- 230000036962 time dependent Effects 0.000 claims 1
- 230000001133 acceleration Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000005284 excitation Effects 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000007689 inspection Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000954 Medium-carbon steel Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000005499 meniscus Effects 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
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Description
本発明は、連続鋳造鋳片の横割れ検知方法及び装置、該検知方法を用いた連続鋳造鋳片の製造方法及び装置に関するものである。 The present invention relates to a method and apparatus for detecting transverse cracks in a continuous cast slab, and a method and apparatus for manufacturing a continuous cast slab using the detection method.
連続鋳造で得られる鋳造鋳片には多種多様な欠陥があり、発生状況は鋳型の機種、鋼種、鋳造サイズ、及び操業条件等で異なる。
これら欠陥のうち表面縦割れ及び横割れに関しては、特に炭素を０．１〜０．１８％の範囲で含有する鋼の場合に発生しやすいことが良く知られている。これは、初期凝固中にパウダーの流入不足や流入過多により局所的な抜熱の不均一が生じ、シェル厚が薄くなった部分で歪みが発生し、これが割れの芽となり、二次冷却でこの芽の部分が拡大して縦割れ及び横割れになるとされている。
Cast slabs obtained by continuous casting have a wide variety of defects, and the state of occurrence differs depending on the mold type, steel type, casting size, operating conditions, and the like.
Of these defects, it is well known that surface vertical cracks and horizontal cracks are likely to occur particularly in the case of steel containing 0.1 to 0.18% of carbon. This is due to insufficient inflow or excessive inflow of powder during the initial solidification, resulting in uneven local heat removal, and distortion occurs in the part where the shell thickness is reduced, which becomes cracked buds, and this is caused by secondary cooling. It is said that the bud part expands into vertical cracks and horizontal cracks.
鋳造鋳片の縦割れを検知する技術としては、例えば特許文献１に開示された「連続鋳造鋳片の縦割れ検知方法」がある。この特許文献１に開示されたものは、鋳造方向に複数個設置した温度測定素子による鋳型温度の測定結果から、信号のパターン処理（温度低下部が時間と共に下方に移動する現象のパターン化）により、割れの芽の発生を検知する方法である。
また、特許文献２には、鋳造鋳片の表面疵の発生を検知（予知）する技術として「連続鋳造用鋳型に、その鋳造方向及び／又は鋳型幅方向に複数の温度測定素子を設置して鋳型温度を計測し、同時に計測した溶鋼の湯面レベル、及び鋳造速度からオンラインにて伝熱、凝固計算を行い、鋳片シェル厚み及びシェル内温度分布を計算し、この値に基づき、鋳造方向及び鋳型幅方向の鋳片の変形及び応力状態を計算し、引張り応力値又は歪みが、所定値以上になったときに鋳片の表面疵の発生を検知あるいは予知することを特徴とする連続鋳造鋳片の表面疵予知方法。」が開示されている。
さらに、特許文献３には、鋳造鋳片の表面欠陥を検知する技術ではないが、鋳型と鋳造鋳片の間に生じる摩擦力を測定し、摩擦力が定常時の1.5〜2.0倍以上のときにブレークアウトの発生の危険があるとして、オッシレーションのストロークを大きくする等によりブレークアウトを防止する技術が開示されている。
As a technique for detecting a vertical crack in a cast slab, for example, there is a “longitudinal crack detection method for a continuous cast slab” disclosed in Patent Document 1. What is disclosed in this Patent Document 1 is based on the measurement result of the mold temperature by a plurality of temperature measuring elements installed in the casting direction, and by signal pattern processing (patterning of a phenomenon in which the temperature lowering portion moves downward with time). This is a method for detecting the occurrence of cracked buds.
Patent Document 2 discloses a technique for detecting (predicting) the occurrence of surface flaws in a cast slab by “installing a continuous casting mold with a plurality of temperature measuring elements in its casting direction and / or mold width direction”. The mold temperature is measured, heat transfer and solidification calculations are performed online from the molten steel surface level and casting speed measured at the same time, and the slab shell thickness and shell temperature distribution are calculated. Based on these values, the casting direction And the deformation and stress state of the slab in the mold width direction are calculated, and the occurrence of surface flaws on the slab is detected or predicted when the tensile stress value or strain exceeds a predetermined value. "A method for predicting surface defects of slabs."
Furthermore, Patent Document 3 is not a technique for detecting a surface defect of a cast slab, but when the friction force generated between the mold and the cast slab is measured and the friction force is 1.5 to 2.0 times or more of the steady state. For example, there is disclosed a technique for preventing breakout by increasing the stroke of oscillation, for example.
特許文献１に開示された発明は、鋳造鋳片内の状態を知る手段として、温度測定素子の情報を利用しているため、温度測定素子が設置されていない場所での割れの発生を検知することはできない。特に、横割れは鋳造方向に対して直交する方向で発生するものであるから、鋳型内で鋳造鋳片に発生した横割れの核を温度変化として捉えることは非常に難しい。 Since the invention disclosed in Patent Document 1 uses the information of the temperature measuring element as a means for knowing the state in the cast slab, the occurrence of a crack at a place where the temperature measuring element is not installed is detected. It is not possible. In particular, since lateral cracks occur in a direction perpendicular to the casting direction, it is very difficult to capture the nucleus of the lateral cracks generated in the cast slab as a temperature change in the mold.
また、特許文献２に開示された発明も、温度測定素子による温度データを取得していることから、上記の特許文献１と同様に横割れの核を捉えるのは難しい。また、特許文献２の発明は、温度データと伝熱計算を組み合わせることで初期凝固シェル全面において割れの芽を推定しているが、鋳型内ではパウダー状態（ガラス、結晶、液体）やエアギャップ、シェルの変形などといった事象が複雑に影響しあっているため、容易に、かつ、正確に鋳造鋳片内の状態を推定することは極めて困難であり、これに基づいて横割れ発生を正確に予測するのは難しい。 Moreover, since the invention disclosed in Patent Document 2 also acquires temperature data from the temperature measuring element, it is difficult to capture the nucleus of the transverse crack as in Patent Document 1 described above. In addition, the invention of Patent Document 2 estimates crack buds on the entire surface of the initial solidified shell by combining temperature data and heat transfer calculation, but in the mold, powder state (glass, crystal, liquid), air gap, Due to complex influences such as shell deformation, it is extremely difficult to estimate the state in the cast slab easily and accurately. Based on this, it is possible to accurately predict the occurrence of transverse cracks. Difficult to do.
特許文献３の技術は、鋳型と鋳造鋳片間に生じた摩擦力が定常時よりも増加したことをブレークアウトの発生と関連付けている。このように鋳型と鋳片間の摩擦力の測定は行われていたが、摩擦力の増加と横割れ発生との関係は不明であった。 The technique of Patent Document 3 relates to the occurrence of breakout that the frictional force generated between the mold and the cast slab is increased from that in the steady state. Thus, the frictional force between the mold and the slab was measured, but the relationship between the increase in the frictional force and the occurrence of lateral cracking was unknown.
以上のように、鋳造中に横割れの発生を検知して、横割れ発生の危険がある時に何らかの対策をとり、横割れによる鋳造鋳片の品質低下を最小限に抑える方法として有効なものがないのが現状である。
本発明は係る課題を解決するためになされたものであり、横割れ発生を正確に検知すること、及びこの検知に基づいて横割れのない高品質な鋳造鋳片を製造する技術を提供することを目的としている。
As mentioned above, it is effective to detect the occurrence of transverse cracks during casting, take some measures when there is a risk of transverse cracks, and minimize the deterioration of cast slab quality due to transverse cracks. There is no current situation.
The present invention has been made in order to solve such problems, and provides a technique for accurately detecting the occurrence of transverse cracks and producing a high-quality cast slab free of transverse cracks based on this detection. It is an object.
鋳型内における凝固シェルの状態を推定する方法としては、鋳型内に設置した温度測定素子を用いるのが一般的である。
確かに、縦割れは鋳造方向に生ずる割れであり、例えば鋳型上部（メニスカスに近い部位）で鋳造鋳片に割れの核が生じた場合、これが鋳型下部の鋳造鋳片にも影響するため、温度測定素子による検知が可能である。
しかし、横割れの核の場合、鋳造方向と直交する鋳型幅方向に生ずる割れであるから、鋳造鋳片が引き抜かれるときにタイミングよく検知できない限り検知するのは難しい。
As a method for estimating the state of the solidified shell in the mold, a temperature measuring element installed in the mold is generally used.
Certainly, vertical cracks are cracks that occur in the casting direction. For example, if crack nuclei occur in the cast slab at the upper part of the mold (site close to the meniscus), this also affects the cast slab at the lower part of the mold. Detection by a measuring element is possible.
However, since the core of a transverse crack is a crack that occurs in the mold width direction orthogonal to the casting direction, it is difficult to detect unless the casting slab can be detected with good timing.
確かに、温度測定素子によって検知可能な凝固シェルの厚みの変化は横割れの発生原因として、間接的には関連している。
しかし、直接的には、鋳造鋳片に引張り応力や圧縮応力が不均一に作用し、これによってオシレーションマークの深さのばらつきや局所的な応力集中が発生して、鋳造鋳片表面の横割れの要因が生成すると考えられる。
そこで、発明者は、横割れの発生は凝固シェルの鋳造方向に発生する応力と相関があるのではないかと考え、このような応力の発生を鋳型と鋳造鋳片間の摩擦力の変化で捉えることを考えた。
本発明は以上の考えに基づくものであり、具体的には以下の構成を備えている。
Certainly, the change in thickness of the solidified shell that can be detected by the temperature measuring element is indirectly related to the cause of the occurrence of transverse cracks.
However, directly, the tensile stress and compressive stress act on the cast slab non-uniformly, which causes variations in the depth of the oscillation mark and local stress concentration, resulting in lateral movement of the cast slab surface. It is thought that a cracking factor is generated.
Therefore, the inventor thinks that the occurrence of transverse cracks has a correlation with the stress generated in the casting direction of the solidified shell, and captures the occurrence of such stress by the change in the frictional force between the mold and the cast slab. I thought.
The present invention is based on the above idea, and specifically includes the following configuration.
（１）本発明に係る連続鋳造鋳片の横割れ検知方法は、オンライン時及びオフライン時における鋳型加振時の負荷の時間離散データに基づいて鋳型と鋳造鋳片間に生じる摩擦力を算出し、算出した摩擦力の摩擦力変動係数（＝摩擦力の標準偏差／平均値×１００［％］）が予め設定した閾値を超えた時に横割れ発生の危険があると検知することを特徴とするものである。 (1) The method for detecting transverse cracks in a continuous cast slab according to the present invention calculates the frictional force generated between the mold and the cast slab based on the time discrete data of the load when the mold is oscillated on-line and off-line. When the calculated frictional coefficient of frictional force (= standard deviation of frictional force / average value × 100 [%]) exceeds a preset threshold, it is detected that there is a risk of occurrence of lateral cracking. Is.
（２）本発明に係る連続鋳造鋳片の横割れ検知方法は、オンライン時及びオフライン時における鋳型加振時の振動変位及び負荷の時間離散データに基づいて鋳型と鋳造鋳片間に生じる摩擦力を算出し、算出した摩擦力の摩擦力変動係数（＝摩擦力の標準偏差／平均値×１００［％］）が予め設定した閾値を超えた時に横割れ発生の危険があると検知することを特徴とするものである。 (2) The method for detecting transverse cracks in a continuous cast slab according to the present invention includes a frictional force generated between a mold and a cast slab based on vibration displacement and load time discrete data during mold excitation on-line and off-line. And detecting that there is a risk of lateral cracking when the calculated frictional force variation coefficient of frictional force (= standard deviation of frictional force / average value × 100 [%]) exceeds a preset threshold value. It is a feature.
（３）上記（１）又は（２）に記載のものにおいて、前記閾値は１０％であることを特徴とするものである。 (3) In the above (1) or (2), the threshold value is 10%.
（４）本発明に係る連続鋳造鋳片の製造方法は、上記（１）、（２）又は（３）に記載の連続鋳造鋳片の横割れ検知方法を用いた連続鋳造鋳片の製造方法であって、前記横割れ検知方法によって横割れ発生の危険があると検知された場合には、前記摩擦力変動係数が上記（３）に記載の閾値以下となるように操業条件を変更して連続鋳造することを特徴とするものである。 (4) A method for producing a continuous cast slab according to the present invention is a method for producing a continuous cast slab using the method for detecting transverse cracks in a continuous cast slab described in (1), (2) or (3) above. In the case where it is detected that there is a risk of occurrence of lateral cracking by the lateral crack detection method, the operating conditions are changed so that the frictional force variation coefficient is not more than the threshold value described in (3) above. It is characterized by continuous casting.
（５）上記（４）に記載のものにおいて、前記操業条件の変更は、鋳造速度を減速すること及び／又は鋳型の振動振幅を小さくすることを特徴とするものである。 (5) In the above (4), the change of the operating condition is characterized in that the casting speed is reduced and / or the vibration amplitude of the mold is reduced.
（６）本発明に係る連続鋳造鋳片の製造方法は、上記（１）、（２）又は（３）に記載の連続鋳造鋳片の横割れ検知方法を用いた連続鋳造鋳片の製造方法であって、前記横割れ検知方法によって横割れ発生の危険があると検知された場合には、製造された連続鋳造鋳片を検品し、横割れ部を手入れすることを特徴とするものである。 (6) A method for producing a continuous cast slab according to the present invention is a method for producing a continuous cast slab using the method for detecting transverse cracks in a continuous cast slab described in (1), (2) or (3) above. And when it is detected that there is a risk of the occurrence of lateral cracking by the lateral crack detection method, the manufactured continuous cast slab is inspected and the lateral cracking part is maintained. .
（７）本発明に係る連続鋳造鋳片の横割れ検知装置は、オシレーション装置の油圧シリンダーの油圧計の情報を入力して摩擦力を演算する摩擦力演算手段と、該摩擦力演算手段の演算結果に基づいて摩擦力変動係数（＝摩擦力の標準偏差／平均値×１００［％］）を演算する摩擦力変動係数演算手段と、該摩擦力演算手段の演算結果と予め設定した閾値とに基づいて横割れ発生の危険の有無、手入れの要否を判定する判定手段とを備えたことを特徴とするものである。 (7) A lateral crack detection device for continuous cast slabs according to the present invention includes a friction force calculation means for inputting a hydraulic gauge information of a hydraulic cylinder of an oscillation device to calculate a friction force, and a friction force calculation means Friction force fluctuation coefficient calculating means for calculating a friction force fluctuation coefficient (= standard deviation of friction force / average value × 100 [%]) based on the calculation result, a calculation result of the friction force calculating means, and a preset threshold value And determining means for determining whether or not there is a risk of occurrence of lateral cracking and whether or not care is required.
（８）本発明に係る連続鋳造鋳片の横割れ検知装置は、オシレーション装置の油圧シリンダーの油圧計の情報と鋳型の変位計の情報を入力して摩擦力を演算する摩擦力演算手段と、該摩擦力演算手段の演算結果に基づいて摩擦力変動係数（＝摩擦力の標準偏差／平均値×１００［％］）を演算する摩擦力変動係数演算手段と、該摩擦力演算手段の演算結果と予め設定した閾値とに基づいて横割れ発生の危険の有無、手入れの要否を判定する判定手段とを備えたことを特徴とするものである。 (8) A transverse crack detection device for a continuous cast slab according to the present invention includes a friction force calculation means for calculating a friction force by inputting information on a hydraulic gauge of a hydraulic cylinder of an oscillation device and information on a displacement meter of a mold. Friction force fluctuation coefficient calculation means for calculating a friction force fluctuation coefficient (= standard deviation of friction force / average value × 100 [%]) based on the calculation result of the friction force calculation means, and calculation of the friction force calculation means It is characterized by comprising determination means for determining whether or not there is a risk of occurrence of transverse cracking based on a result and a preset threshold value, and whether or not care is required.
（９）上記（７）又は（８）に記載のものにおいて、前記閾値は１０％であることを特徴とするものである。 (9) In the above (7) or (8), the threshold value is 10%.
（１０）本発明に係る連続鋳造鋳片製造装置は、上記（７）、（８）又は（９）に記載の連続鋳造鋳片の横割れ検知装置を備えた連続鋳造鋳片の製造装置であって、前記判定手段によって横割れ発生の危険があると判定されたときに、摩擦力変動係数を小さくするために操業条件を変更する操業条件変更手段を有し、該操業条件変更手段は、鋳造速度を減速するようにピンチローラ制御装置を制御する及び／又は鋳型の振動振幅を小さくするように加振装置を制御することを特徴とするものである。 (10) A continuous cast slab manufacturing apparatus according to the present invention is a continuous cast slab manufacturing apparatus provided with the transverse crack detection device for a continuous cast slab according to (7), (8) or (9). Then, when it is determined by the determination means that there is a risk of occurrence of lateral cracking, it has an operation condition change means for changing the operation condition in order to reduce the frictional force variation coefficient, the operation condition change means, The pinch roller control device is controlled to reduce the casting speed and / or the vibration device is controlled to reduce the vibration amplitude of the mold.
本発明においては、オンライン時及びオフライン時における鋳型加振時の負荷の時間離散データに基づいて鋳型と鋳造鋳片間に生じる摩擦力を算出し、算出した摩擦力の摩擦力変動係数（＝摩擦力の標準偏差／平均値×１００［％］）が予め設定した閾値を超えた時に横割れ発生の危険があると検知するようにしたので、横割れの発生を的確に検知することができ、この検知情報を基にして鋳造速度又は鋳型振動振幅等の操業条件を変更あるいは鋳造鋳片を手入れすることにより、横割れのない高品質な鋳造鋳片を製造することができる。 In the present invention, the frictional force generated between the mold and the cast slab is calculated based on the time discrete data of the load when the mold is oscillated on-line and off-line, and the frictional coefficient of friction (= friction) When the standard deviation of force / average value x 100 [%]) exceeds a preset threshold, it is detected that there is a risk of transverse cracking, so the occurrence of transverse cracking can be accurately detected, Based on this detection information, it is possible to manufacture a high-quality cast slab free from transverse cracks by changing the operating conditions such as casting speed or mold vibration amplitude or by maintaining the cast slab.
［実施の形態１］
図１は本発明の一実施の形態に係る横割れ検知装置を設置した連続鋳造設備の説明図である。連続鋳造設備は、鋳型１、鋳型１から出た鋳造鋳片３をガイドするガイドローラ５、鋳造鋳片３を引き抜くピンチローラ７、ピボット９を介したレバー１１の両端に鋳型１と油圧シリンダー１３を配置したオシレーション装置１７を備えている。
このような構成の連続鋳造設備に、以下の構成からなる横割れ検知装置１９が設けられている。
連続鋳造鋳片の横割れ検知装置１９は、オシレーション装置１７の油圧シリンダー１３の油圧計１５の情報及び変位計３１の情報を入力して摩擦力を演算する摩擦力演算手段２１と、該摩擦力演算手段２１の演算結果に基づいて摩擦力変動係数（＝摩擦力の標準偏差／平均値×１００［％］）を演算する摩擦力変動係数演算手段２３と、摩擦力変動係数演算手段２３の演算結果と予め設定した閾値とに基づいて横割れ発生の有無を判定する判定手段２５とを備えている。
以下、各構成をさらに詳細に説明する。
[Embodiment 1]
FIG. 1 is an explanatory diagram of a continuous casting facility in which a transverse crack detection device according to an embodiment of the present invention is installed. The continuous casting equipment includes a mold 1, a guide roller 5 for guiding the cast slab 3 coming out of the mold 1, a pinch roller 7 for extracting the cast slab 3, and a mold 1 and a hydraulic cylinder 13 at both ends of the lever 11 via the pivot 9. Is provided with an oscillation device 17.
The continuous casting equipment having such a configuration is provided with a lateral crack detection device 19 having the following configuration.
The continuous cast slab transverse crack detection device 19 includes a friction force calculation means 21 for calculating the friction force by inputting the information of the hydraulic gauge 15 of the hydraulic cylinder 13 and the information of the displacement meter 31 of the oscillation device 17, and the friction. The frictional force fluctuation coefficient calculating means 23 for calculating the frictional force fluctuation coefficient (= standard deviation of frictional force / average value × 100 [%]) based on the calculation result of the force calculating means 21, and the frictional force fluctuation coefficient calculating means 23 The determination means 25 which determines the presence or absence of a lateral crack generation based on a calculation result and the preset threshold value is provided.
Hereinafter, each configuration will be described in more detail.
＜摩擦力演算手段＞
摩擦力演算手段２１は、油圧シリンダー１３の油圧計１５の情報と鋳型１の変位計３１の情報を入力して摩擦力を演算する。摩擦力の演算には、以下に説明する１）又は２）の２通りの方法のいずれかを用いる。
<Friction force calculation means>
The frictional force calculating means 21 inputs the information of the hydraulic gauge 15 of the hydraulic cylinder 13 and the information of the displacement gauge 31 of the mold 1 to calculate the frictional force. For the calculation of the frictional force, either one of the two methods 1) or 2) described below is used.
１）油圧計１５の情報を用いる方法
オンライン時及びオフライン時における油圧計１５の情報を用いて、摩擦力を演算する方法である。ここで油圧シリンダー１３の油圧計１５の情報とは、油圧シリンダー１３の入側の油圧を計測する入側油圧計１５ａの情報と、油圧シリンダー１３の出側の油圧を計測する出側油圧計１５ｂの情報である。
摩擦力演算手段２１は、上記の情報を入力して、（１）式に基づいて鋳型１と鋳造鋳片３の間に生じる単位面積当たりの摩擦力Ｆを演算する。
F=[(P1×S1-P2×S2)-(P1’×S1-P2’×S2)]×r/[2×(d+w)×Le] ・・・ (1)
ただし、F：単位面積当たりの鋳型と鋳造鋳片間の摩擦力（Ｎ／ｍ２）
S1：油圧シリンダー入側断面積（ｍ２）
S2：油圧シリンダー出側断面積（ｍ２）
P1：オンライン時（鋳造時）の油圧シリンダー入側油圧（Ｐａ）
P2：オンライン時（鋳造時）の油圧シリンダー出側油圧（Ｐａ）
P1’：オフライン時（非鋳造時）の油圧シリンダー入側油圧（Ｐａ）
P2’：オフライン時（非鋳造時）の油圧シリンダー出側油圧（Ｐａ）
r：レバー比（L1/L2）
但し、L1：油圧シリンダロッド軸心線からピボットまでの距離（ｍ）
L2：鋳型厚み中心線からピボットまでの距離（ｍ）
d：鋳造鋳片厚み（ｍ）
w：鋳造鋳片幅（ｍ）
Le:鋳造鋳片有効長（ｍ）
1) Method of using information of hydraulic gauge 15 This is a method of calculating frictional force using information of the hydraulic gauge 15 when online and offline. Here, the information of the hydraulic gauge 15 of the hydraulic cylinder 13 is information of the inlet hydraulic gauge 15a that measures the hydraulic pressure on the inlet side of the hydraulic cylinder 13, and the outlet hydraulic gauge 15b that measures the hydraulic pressure on the outlet side of the hydraulic cylinder 13. Information.
The frictional force calculating means 21 inputs the above information and calculates the frictional force F per unit area generated between the mold 1 and the cast slab 3 based on the equation (1).
F = [(P1 × S1-P2 × S2)-(P1 ′ × S1-P2 ′ × S2)] × r / [2 × (d + w) × Le] (1)
F: Friction force between mold and cast slab per unit area (N / m 2 )
S1: Hydraulic cylinder entry side cross-sectional area (m 2 )
S2: Hydraulic cylinder outlet side cross-sectional area (m 2 )
P1: On-line (casting) hydraulic cylinder inlet side hydraulic pressure (Pa)
P2: Hydraulic cylinder outlet hydraulic pressure (Pa) when online (casting)
P1 ': Hydraulic cylinder inlet side hydraulic pressure (Pa) when offline (non-casting)
P2 ': Hydraulic cylinder outlet hydraulic pressure (Pa) when offline (non-casting)
r: Lever ratio (L1 / L2)
L1: Distance from hydraulic cylinder rod axis to pivot (m)
L2: Distance from mold thickness center line to pivot (m)
d: Cast slab thickness (m)
w: Cast slab width (m)
Le: Cast slab effective length (m)
上記（１）式の導出過程について説明する。
オンライン時（鋳造時）に鋳型１にかかる力は、オシレーション装置１９の加振力（Ｗｆon）、鋳型１と鋳造鋳片３の間に生じる摩擦力（Ｆtotal）である。
また、見かけの鋳型質量をＭ、鋳型１の加速度をａとすると、オンライン時の鋳型１の運動方程式は以下のようになる。
Ｍａ＝Ｗｆon−Ｆtotal ・・・・ （２）
The process of deriving the above equation (1) will be described.
The force applied to the mold 1 when online (during casting) is the vibration force (Wf on ) of the oscillation device 19 and the frictional force (F total ) generated between the mold 1 and the cast slab 3.
Further, assuming that the apparent mold mass is M and the acceleration of the mold 1 is a, the equation of motion of the mold 1 when online is as follows.
Ma = Wf on −F total (2)
また、オフライン時（非鋳造時）には、Ｆtotal＝０となり、またオフライン時のオシレーション装置１９の加振力をＷｆoffとすると、オフライン時の鋳型１の運動方程式は下式（３）となる。
Ｍａ＝Ｗｆoff ・・・・・ （３）
（３）式を（２）式に代入して整理すると下式（４）を得ることができる。
Ｆtotal＝Ｗｆon−Ｗｆoff ・・・・・ （４）
Further, when offline (non-casting), F total = 0, and when the excitation force of the oscillation device 19 when offline is Wf off , the equation of motion of the mold 1 when offline is expressed by the following equation (3). It becomes.
Ma = Wf off (3)
Substituting the expression (3) into the expression (2) and rearranging, the following expression (4) can be obtained.
F total = Wf on -Wf off (4)
ＷｆonおよびＷｆoffは、油圧シリンダー１３の入側圧力Ｐ１（Ｐ１´）と出側圧力Ｐ２（Ｐ２´）を油圧計１５により測定することで、それぞれ求めることができる。
Ｗｆon＝(P1×S1-P2×S2)×r ・・・・・ （５）
Ｗｆoff＝(P1’×S1-P2’×S2)×r ・・・・・ （６）
（４）〜（６）式よりＦtotalは下式（７）によって求まる。
Ｆtotal＝[(P1×S1-P2×S2)-(P1’×S1-P2’×S2)]×r・・・・・ （７）
鋳型１と鋳造鋳片３の間に生じる単位面積当たりの摩擦力Ｆは、（７）式により求めたＦtotalを鋳型１と鋳造鋳片３の接触面積で除することで算出でき、これにより（１）式が導きだされる。
Ｆ＝[(P1×S1-P2×S2)-(P1’×S1-P2’×S2)]×r/[2×(d+w)×Le] ・・・ (1)
Wf on and Wf off can be obtained by measuring the inlet side pressure P1 (P1 ′) and the outlet side pressure P2 (P2 ′) of the hydraulic cylinder 13 with the hydraulic meter 15, respectively.
W fon = (P1 × S1-P2 × S2) × r (5)
W foff = (P1 ′ × S1-P2 ′ × S2) × r (6)
From the equations (4) to (6), F total is obtained by the following equation (7).
F total = [((P1 × S1-P2 × S2) − (P1 ′ × S1-P2 ′ × S2)] × r (7)
The frictional force F per unit area generated between the mold 1 and the cast slab 3 can be calculated by dividing the F total obtained by the equation (7) by the contact area between the mold 1 and the cast slab 3. Equation (1) is derived.
F = [(P1 × S1-P2 × S2) − (P1 ′ × S1-P2 ′ × S2)] × r / [2 × (d + w) × Le] (1)
２）油圧計１５及び変位計３１の情報を用いる方法
オンライン時及びオフライン時における油圧計１５及び変位計３１の情報を用いて、摩擦力を演算する方法である。ここで変位計３１の情報とは、鋳型１の加振時において計測した鋳型１の振動変位の時系列データのことであり、該時系列データを時間に対して２階微分することにより得られる鋳型１の加速度ａが求まる。オンライン時における変位計３１の情報により求まる該加速度ａ及び油圧計１５の情報により求まる鋳型加振力Ｗｆoｎを上式（２）に代入することにより鋳型１と鋳型鋳片３の間に生じる摩擦力Ｆtotalを求め、これを接触面積で除する事で、単位面積あたりの摩擦力Ｆが得られる。
Ｆ＝[(P1×S1-P2×S2)-Ｍａ]×r/[2×(d+w)×Le] ・・・ (9)
2) Method of using information of hydraulic gauge 15 and displacement gauge 31 This is a method of calculating frictional force using information of hydraulic gauge 15 and displacement gauge 31 when online and offline. Here, the information of the displacement meter 31 is time series data of vibration displacement of the mold 1 measured when the mold 1 is vibrated, and is obtained by second-order differentiation of the time series data with respect to time. The acceleration a of the mold 1 is obtained. Friction by substituting the above equation (2) the mold excitation force Wf on which found by the acceleration a and the hydraulic total of 15 information which is obtained by the displacement gauge 31 information during online produced between the mold 1 and the mold slab 3 By obtaining the force F total and dividing this by the contact area, the friction force F per unit area is obtained.
F = [(P1 × S1-P2 × S2) −Ma] × r / [2 × (d + w) × Le] (9)
上記１）及び２）のいずれの方法において、鋳型１の見かけの質量Ｍは油圧シリンダー１３により鋳型１を振動させる際に生じる減衰の効果を含んだものである。上記２）の方法では、上式（３）に示したオフライン時（非鋳造時）における鋳型１の運動方程式にオフライン時における変位計３１の情報により求まる該加速度ａ及び油圧計１５の情報により求まる鋳型加振力Ｗｆoffを代入することにより求めた見かけの質量Ｍを用いる。 In any of the above methods 1) and 2), the apparent mass M of the mold 1 includes the effect of damping that occurs when the hydraulic cylinder 13 vibrates the mold 1. In the above method 2), the equation of motion of the mold 1 in the off-line time (non-casting) shown in the above equation (3) is obtained from the acceleration a obtained from the information in the displacement meter 31 in the off-line and the information in the hydraulic pressure meter 15. The apparent mass M obtained by substituting the mold excitation force Wf off is used.
さらに、鋳型振動１周期の間に摩擦力は周期的に変動するため、どのような方法で代表値を求めるかという問題があるが、これについては、摩擦力は鋳型振動1周期毎における振幅すなわち最大値と最小値の差を代表値とし、その代表値の集まりの中で標準偏差を求める方法をとった。 Further, since the frictional force periodically changes during one cycle of the mold vibration, there is a problem of how to obtain a representative value. The difference between the maximum value and the minimum value was used as a representative value, and a standard deviation was obtained from the collection of representative values.
＜摩擦力変動係数演算手段＞
摩擦力変動係数演算手段２３は、摩擦力演算手段２１の演算結果に基づいて摩擦力変動係数（＝摩擦力の標準偏差／平均値×１００［％］）を演算する。
なお、摩擦力変動係数は、摩擦力の標準偏差及び平均値に基づいて算出しているため、摩擦力は時間離散データセットとして提供する必要がある。その際の離散間隔、すなわちサンプリング周期は、鋳型振動の１周期の10分の１より短い間隔でサンプリングするのが好ましい。具体的には、鋳型振動1周期は最も短いものが260ｍｓ程度であるから、サンプリング周期は20ｍｓで行うようにすればよい。
<Friction force fluctuation coefficient calculation means>
The frictional force variation coefficient calculating unit 23 calculates a frictional force variation coefficient (= standard deviation of frictional force / average value × 100 [%]) based on the calculation result of the frictional force calculating unit 21.
In addition, since the frictional force variation coefficient is calculated based on the standard deviation and average value of the frictional force, it is necessary to provide the frictional force as a time discrete data set. In this case, it is preferable to sample at a discrete interval, that is, a sampling cycle, which is shorter than 1/10 of one cycle of the mold vibration. Specifically, the shortest mold vibration period is about 260 ms, so the sampling period may be 20 ms.
ここで、鋳造鋳片３の横割れを検知するに際して、摩擦力変動係数を求める方法を用いた理由について説明する。
前述したように、横割れの発生は、凝固シェル内の鋳造方向に大きな応力が発生することと相関があると考えられ、このような応力の発生は鋳型１と鋳造鋳片３の間に生じる摩擦力の変化で捉えることができる。
発明者は、摩擦力の変化を摩擦力変動係数（＝摩擦力の標準偏差／平均値×１００［％］）により評価し、摩擦力変動係数（％）と横割れ手入れ面積（ｍ2）の関係を調査した。その結果を図２に示す。図２は、横軸が摩擦力変動係数（％）を示し、縦軸が横割れ手入れ面積（ｍ2）を示している。
図２に示されるように、摩擦力変動係数と横割れ手入れ面積の間には明らかな相関がみられる。摩擦力変動係数が１０％以下では横割れ手入れ面積はほぼ０（零）ｍ2であり、摩擦力変動係数が１０％を超えると横割れ手入れ面積が徐々に増加し、摩擦力変動係数が１４％では横割れ手入れ面積が約１ｍ2である。また、摩擦力変動係数が１４％を超えたあたりから横割れ手入れ面積は急激に増加している。
以上のことから、摩擦力変動係数によって横割れ発生の検知が可能であり、かつ摩擦力変動係数の所定の値を閾値として横割れ発生の有無及び手入れの要否を判定することができる。
Here, the reason for using the method for obtaining the frictional force variation coefficient when detecting the lateral cracking of the cast slab 3 will be described.
As described above, the occurrence of transverse cracks is considered to have a correlation with the occurrence of a large stress in the casting direction in the solidified shell, and the occurrence of such a stress occurs between the mold 1 and the cast slab 3. It can be captured by the change in frictional force.
The inventor evaluates the change of the frictional force by the frictional force variation coefficient (= standard deviation of frictional force / average value × 100 [%]), and determines the frictional force variation coefficient (%) and the lateral crack maintenance area (m 2 ). The relationship was investigated. The result is shown in FIG. In FIG. 2, the horizontal axis represents the coefficient of frictional force variation (%), and the vertical axis represents the lateral crack maintenance area (m 2 ).
As shown in FIG. 2, there is a clear correlation between the coefficient of frictional force variation and the lateral crack maintenance area. When the frictional force variation coefficient is 10% or less, the lateral crack maintenance area is almost 0 (zero) m 2. When the frictional force variation coefficient exceeds 10%, the lateral crack maintenance area gradually increases and the frictional force variation coefficient is 14 %, The lateral cracking area is about 1 m 2 . Further, since the coefficient of frictional force variation exceeds 14%, the lateral crack maintenance area has increased rapidly.
From the above, it is possible to detect the occurrence of lateral cracking by the frictional force variation coefficient, and to determine whether or not lateral cracking has occurred and whether or not it needs to be maintained using a predetermined value of the frictional force variation coefficient as a threshold value.
＜判定手段＞
判定手段２５は、摩擦力変動係数演算手段２３の演算結果と、予め設定した閾値とに基づいて横割れ発生の有無ならびに手入れの要否を判定する。前記図２より、摩擦力変動係数が１０％以下では横割れ手入れ面積はほぼ０ｍ2、であることから、摩擦力変動係数の値１０％を閾値として、１０％以下では横割れ発生無し、１０％超では横割れ発生有りと判定する。また、摩擦力変動係数の値が１０％から１４％においては横割れ手入れ面積は1ｍ2以下であり、手入れは不要とみなされる許容範囲であると判定する。さらに、摩擦力変動係数の値が１４％を超えた場合、当該部位には手入れが必要であると判定する。
<Determination means>
The determination means 25 determines the presence or absence of occurrence of lateral cracks and the necessity of maintenance based on the calculation result of the frictional force variation coefficient calculation means 23 and a preset threshold value. From FIG. 2, the lateral crack maintenance area is almost 0 m 2 when the frictional force variation coefficient is 10% or less. Therefore, no lateral cracking occurs when the frictional force variation coefficient value is 10% or less and the threshold is 10% or less. If it exceeds%, it is determined that a transverse crack has occurred. Further, when the value of the coefficient of frictional variation is 10% to 14%, the lateral crack maintenance area is 1 m 2 or less, and it is determined that the maintenance is an allowable range that is considered unnecessary. Furthermore, when the value of the frictional force variation coefficient exceeds 14%, it is determined that the part needs to be maintained.
次に、本発明の連続鋳造鋳片の横割れ検知方法を、上述した連続鋳造鋳片の横割れ検知装置１９の動作と共に説明する。
摩擦力演算手段２１には、オフライン時において計測した油圧シリンダー入側油圧P1’、 油圧シリンダー出側油圧P2’の値を入力しておく。
オンライン時において、入側油圧計１５ａ及び出側油圧計１５ｂから油圧シリンダー１３の入側油圧P1及び出側油圧P2を、変位計３１から鋳型１の振動変位を入力し、摩擦力演算手段２１において（１）式又は（９）式に基づいて鋳型と鋳造鋳片間の摩擦力を演算する。
摩擦力変動係数演算手段２３においては、摩擦力変動係数（＝摩擦力の標準偏差／平均値×１００［％］）を演算する。
判定手段２５では、摩擦力変動係数演算手段２３の演算結果に基づいて、横割れの発生の有無又は手入れの要否を判定する。
例えば、摩擦力変動係数が１０％以下であれば、横割れ発生の危険無しと判定し、摩擦力変動係数が１０％を超えたときには、横割れ発生の危険有りと判定する。そして、横割れ発生の危険有りと判定され、摩擦力変動係数が１４％以上の許容範囲を超えた場合には、鋳造鋳片における横割れ発生部位を特定して、当該部位について手入れをするようにすればよい。
Next, a method for detecting transverse cracks in a continuous cast slab according to the present invention will be described together with the operation of the above-described transverse crack detection device 19 for continuous cast slabs.
The frictional force calculating means 21 is inputted with values of the hydraulic cylinder inlet side hydraulic pressure P1 ′ and the hydraulic cylinder outlet side hydraulic pressure P2 ′ measured in the offline state.
At the time of online, the inlet side hydraulic pressure gauge 15a and the outlet side hydraulic gauge 15b input the inlet side hydraulic pressure P1 and the outlet side hydraulic pressure P2, and the vibration displacement of the mold 1 is input from the displacement gauge 31. The frictional force between the mold and the cast slab is calculated based on the formula (1) or the formula (9).
The frictional force variation coefficient calculating means 23 calculates a frictional force variation coefficient (= standard deviation of frictional force / average value × 100 [%]).
Based on the calculation result of the frictional force variation coefficient calculation unit 23, the determination unit 25 determines whether or not a lateral crack has occurred or whether or not care is required.
For example, when the frictional force variation coefficient is 10% or less, it is determined that there is no risk of lateral cracking, and when the frictional force variation coefficient exceeds 10%, it is determined that there is a risk of lateral cracking. And when it is determined that there is a risk of occurrence of lateral cracking and the coefficient of frictional force fluctuation exceeds the allowable range of 14% or more, the lateral crack occurrence part in the cast slab is identified and the part concerned is cleaned. You can do it.
以上のように、本実施の形態においては、オンライン時及びオフライン時における鋳型加振時の負荷の時間離散データに基づいて鋳型１と鋳造鋳片３の間に生じる摩擦力を算出し、算出した摩擦力から演算する摩擦力変動係数が予め設定した閾値を超えたときに横割れ発生の危険があると検知するため、この検知結果に基づいて横割れのない高品質な鋳造鋳片を製造することが可能となる。 As described above, in the present embodiment, the frictional force generated between the mold 1 and the cast slab 3 is calculated on the basis of the time discrete data of the load at the time of mold vibration in online and offline, and calculated. In order to detect that there is a risk of lateral cracking when the frictional force variation coefficient calculated from the frictional force exceeds a preset threshold, a high-quality cast slab without lateral cracking is manufactured based on this detection result. It becomes possible.
なお、上記の説明において、鋳型１と鋳造鋳片３の間に生じる摩擦力を算出する（１）式は、ピボット９を介したレバー１１の両端に鋳型１と油圧シリンダー１３を配置したオシレーション装置１７に関するものであるが、オシレーション装置の形式はこれに特定されず、例えば、鋳型に油圧シリンダーを直結した直動タイプの油圧式振動装置であってもよい。その場合はｒ＝１となる。 In the above description, the equation (1) for calculating the frictional force generated between the mold 1 and the cast slab 3 is an oscillation in which the mold 1 and the hydraulic cylinder 13 are arranged at both ends of the lever 11 via the pivot 9. Although it relates to the device 17, the type of the oscillation device is not limited to this, and may be, for example, a direct acting type hydraulic vibration device in which a hydraulic cylinder is directly connected to a mold. In that case, r = 1.
［実施の形態２］
本実施の形態は、実施の形態１の連続鋳造鋳片の横割れ検知装置１９を用いた連続鋳造鋳片の製造装置に関するものであり、図３に示すように、実施の形態１で説明した横割れ検知装置１９に加えて、操業条件変更手段２７及びピンチローラ制御装置２９を備えている。
以下、各構成をさらに詳細に説明する。
[Embodiment 2]
The present embodiment relates to a continuous cast slab manufacturing apparatus using the continuous cast slab transverse crack detection device 19 of the first embodiment, and has been described in the first embodiment as shown in FIG. In addition to the lateral crack detection device 19, an operation condition changing means 27 and a pinch roller control device 29 are provided.
Hereinafter, each configuration will be described in more detail.
＜操業条件変更手段＞
操業条件変更手段２７は、判定手段によって横割れ発生の危険が有りと判定されたときに、ピンチローラ制御装置２９に対して鋳造速度を低下させる旨の指示を出す。速度低下の度合いについては、予め設定しておくのが好ましい。
<Operation condition change means>
The operating condition changing means 27 gives an instruction to the pinch roller control device 29 to reduce the casting speed when it is determined by the determining means that there is a risk of occurrence of lateral cracking. The degree of speed reduction is preferably set in advance.
＜ピンチローラ制御装置＞
ピンチローラ制御装置２９は、操業条件変更手段２７からの指示に基づいてピンチローラの回転数を制御することで、引抜き速度を制御する。具体的には、操業条件変更手段２７から鋳造速度低下の指示があったときに、ピンチローラ制御装置２９はピンチローラの回転数を下げて鋳造鋳片の引抜き速度を低下させることにより、鋳造速度を低下させる。
<Pinch roller control device>
The pinch roller control device 29 controls the drawing speed by controlling the number of rotations of the pinch roller based on an instruction from the operation condition changing means 27. Specifically, when there is an instruction to lower the casting speed from the operating condition changing means 27, the pinch roller control device 29 lowers the number of rotations of the pinch roller to lower the drawing speed of the cast slab, thereby reducing the casting speed. Reduce.
次に、本発明の横割れ検知装置１９に加えて操業条件変更手段２７及びピンチローラ操業装置２９を用いた連続鋳造鋳片製造方法を説明する。
連続鋳造装置のオンライン時における鋳型加振時の負荷の時間離散データに基づいて、鋳型と鋳造鋳片間の摩擦力を算出する。算出した摩擦力から演算した摩擦力変動係数が予め設定した閾値を超えた場合、操業条件変更手段２７からピンチローラ制御装置２９に鋳造速度を低下させる旨の指示を出す。
Next, a continuous cast slab manufacturing method using the operation condition changing means 27 and the pinch roller operation device 29 in addition to the lateral crack detection device 19 of the present invention will be described.
The frictional force between the mold and the cast slab is calculated based on the time discrete data of the load when the mold is vibrated when the continuous casting apparatus is online. When the frictional force variation coefficient calculated from the calculated frictional force exceeds a preset threshold value, the operation condition changing unit 27 instructs the pinch roller control device 29 to reduce the casting speed.
以上のように、本実施の形態においては、横割れ検知装置１９を用いて得られた摩擦力変動係数に基づいて操業条件変更手段２７からピンチローラ制御装置２９へ指示を出してピンチローラ回転数を制御することにより、鋳造鋳片の横割れ発生を防ぎ、高品質な鋳造鋳片を製造することが可能となる。
なお、上記の説明において、操業条件の変更は、ピンチローラ制御装置１９による鋳造速度の低下によって摩擦力変動係数を所定値以下になるようにしたが、摩擦力変動係数を低下させる他の方法として、鋳型振動振幅を小さくする方法がある。
As described above, in the present embodiment, the operation condition changing means 27 gives an instruction to the pinch roller control device 29 based on the frictional force variation coefficient obtained by using the transverse crack detection device 19, and the pinch roller rotation speed. By controlling the above, it is possible to prevent the occurrence of transverse cracks in the cast slab and to manufacture a high-quality cast slab.
In the above description, the operating condition is changed by setting the frictional force variation coefficient to a predetermined value or less by reducing the casting speed by the pinch roller control device 19, but as another method for reducing the frictional force variation coefficient. There is a method of reducing the mold vibration amplitude.
表1にいくつかの鋳造速度、鋳型振動振幅と摩擦力変動係数及び鋳造鋳片表面における横割れの有無の関係を示す。 Table 1 shows the relationship between several casting speeds, mold vibration amplitude and coefficient of friction variation, and the presence or absence of transverse cracks on the cast slab surface.
鋳造速度Vcを一定にし、鋳型振動振幅を変化させたケースに着目する。ケース１および２はVc=1.3m/min、ケース４および５はVc=1.6m/min、ケース７および８はVc=2.0m/min、ケース９および１０はVc=2.1m/minで鋳造速度を一定にし、それぞれ鋳型振動振幅を4mmまたは7mmで鋳造したケースである。いずれも、鋳造速度が一定の場合、鋳型振動振幅を4mmで鋳造したケースに比べ7mmで鋳造したケースの方が、摩擦力変動係数が増加している。これにより、鋳型振動振幅を減ずることで、摩擦力変動係数を低減できることが実証された。
また、鋳造速度Vcを変化させ、鋳型振動振幅が一定にしたケースに着目する。ケース１、３、４、７、９、１０はVcを1.3m/min〜2.1m/minの間で変化させ、鋳型振動振幅を4mmで鋳造したケースである。鋳造速度Vcが増加するにつれ、摩擦力変動係数が増加している。これにより、鋳造速度を低下させることで、摩擦力変動係数を低減できることが実証された。
次に、摩擦力変動係数の変化と鋳造鋳片の横割れの有無に着目する。ケース１〜ケース７は摩擦力変動係数が１０％以下になるケースであり、鋳造鋳片表面において横割れは発生していない。しかし、ケース８〜ケース１１は摩擦力変動係数が１０％以上となるケースであり、鋳造鋳片表面の横割れが発生している。これにより、摩擦力変動係数を１０％以下にすることで、鋳造鋳片表面の横割れ発生を抑制できることが実証された。
Pay attention to the case where the casting speed Vc is constant and the mold vibration amplitude is changed. Cases 1 and 2 have Vc = 1.3 m / min, cases 4 and 5 have Vc = 1.6 m / min, cases 7 and 8 have Vc = 2.0 m / min, cases 9 and 10 have Vc = 2.1 m / min, and casting speed The cases were cast with a mold vibration amplitude of 4 mm or 7 mm, respectively. In both cases, when the casting speed is constant, the coefficient of frictional force variation is increased in the case cast at 7 mm compared to the case cast at a mold vibration amplitude of 4 mm. As a result, it was demonstrated that the coefficient of frictional force variation can be reduced by reducing the mold vibration amplitude.
Also, focus on the case where the casting speed Vc is changed and the mold vibration amplitude is constant. Cases 1, 3, 4, 7, 9, and 10 are cases where Vc was changed between 1.3 m / min and 2.1 m / min, and the mold vibration amplitude was cast at 4 mm. As the casting speed Vc increases, the frictional force variation coefficient increases. This proved that the coefficient of frictional force variation can be reduced by reducing the casting speed.
Next, attention is paid to the change in coefficient of frictional force variation and the presence or absence of transverse cracks in the cast slab. Cases 1 to 7 are cases in which the coefficient of variation in friction force is 10% or less, and no transverse cracks are generated on the cast slab surface. However, Case 8 to Case 11 are cases in which the coefficient of frictional force variation is 10% or more, and lateral cracks occur on the cast slab surface. Thereby, it was proved that the occurrence of transverse cracks on the surface of the cast slab can be suppressed by setting the frictional force variation coefficient to 10% or less.
以上より、鋳造速度を低下及び／又は鋳型振動振幅を小さくすることで摩擦力変動係数を低減することができ、摩擦力変動係数が１０％以下であった鋳造鋳片表面には横割れ発生が見られなかったことが実証された。 As described above, the frictional force variation coefficient can be reduced by reducing the casting speed and / or reducing the mold vibration amplitude, and the occurrence of transverse cracks on the cast slab surface where the frictional force variation coefficient was 10% or less. It was proved that it was not seen.
本発明の効果を確認すべく実施した確認実験の効果について説明する。実験では垂直曲げ型連続鋳造機を用いて中炭素鋼を鋳造した。鋳造鋳片の幅は2100mm、厚みは250mm、鋳造速度は2.0m/minを選択した。
実験により得られた鋳造鋳片をいくつか抜き出し、表面検品を実施することで、本発明の効果を確認した。
図４は本実験の摩擦力変動係数の時間変化を示すグラフであり、縦軸が摩擦力変動係数（１分間）［％］で、横軸が鋳造時間［min］を示している。摩擦力変動係数の算出は過去１分間の離散時間データに対して行った。鋳造時間を所定の時間で区切り、その区間毎の鋳片１〜８（図４参照）について検品することにより横割れの有無を確認した。
The effect of the confirmation experiment conducted to confirm the effect of the present invention will be described. In the experiment, medium carbon steel was cast using a vertical bending type continuous casting machine. The width of the cast slab was 2100 mm, the thickness was 250 mm, and the casting speed was 2.0 m / min.
Several cast cast pieces obtained by experiment were extracted, and surface inspection was performed to confirm the effect of the present invention.
FIG. 4 is a graph showing the change over time of the frictional force variation coefficient in this experiment. The vertical axis represents the frictional force variation coefficient (1 minute) [%], and the horizontal axis represents the casting time [min]. The calculation of the coefficient of friction variation was performed on discrete time data for the past 1 minute. The casting time was divided by a predetermined time, and the presence or absence of transverse cracks was confirmed by inspecting the cast pieces 1 to 8 (see FIG. 4) for each section.
鋳片の検品の結果を表２に示す。
摩擦力変動係数が１０％を超えている鋳造時間帯に製造された鋳片４、５、８においては横割れが発生していた。他方、摩擦力変動係数が１０％以下の鋳片１〜３、６、７には横割れは発生していなかった。このことより、摩擦力変動係数が１０％超えた鋳造鋳片のみを検品・手入れの対象とすればよいことがわかる。また、実際に手入れをするか否かは、摩擦力変動係数の閾値を予め決めておいて、該閾値を超えた鋳造鋳片のみを検品・手入れするようにすればよい。 In the slabs 4, 5, and 8 manufactured in the casting time zone in which the frictional force variation coefficient exceeds 10%, transverse cracks occurred. On the other hand, transverse cracks did not occur in slabs 1 to 3, 6, and 7 having a coefficient of friction variation of 10% or less. From this, it can be seen that only the cast slab whose frictional force variation coefficient exceeds 10% should be subject to inspection and maintenance. Whether or not to actually perform the maintenance may be determined by preliminarily determining a threshold value of the frictional force variation coefficient, and inspecting and maintaining only cast slabs exceeding the threshold value.
次に、図４に示すように、鋳造工程において摩擦力変動係数が１０％を超えることを予想された（摩擦力変動係数が９％を超えた）ので、図５に示すように鋳造速度を2.0m/minから1.6m/minに減速したところ、摩擦力変動係数は減少した。鋳片の検品の結果を表３に示す。減速前後の鋳片の検品を行ったところ、横割れは発生していなかった。
以上のように、鋳造中に鋳型と鋳造鋳片間に生じる摩擦力を算出し、摩擦力変動係数が１０％を超え、横割れが発生すると検知された時に操業条件変更手段及びピンチローラ制御手段を用いて鋳造速度を低下させる等、鋳造の操業条件を変更することで、横割れの無い高品質な鋳造鋳片を製造できることが確認された。 As described above, the frictional force generated between the mold and the cast slab during casting is calculated, and when it is detected that the coefficient of variation of frictional force exceeds 10% and a lateral crack occurs, the operating condition changing means and the pinch roller control means It was confirmed that high-quality cast slabs without transverse cracks can be produced by changing the operating conditions of casting, such as reducing the casting speed with the use of.
１ 鋳型
３ 鋳造鋳片
５ ガイドローラ
７ ピンチローラ
９ ピボット
１１ レバー
１３ 油圧シリンダー
１５ 油圧計
１５ａ 入側油圧計
１５ｂ 出側油圧計
１７ オシレーション装置
１９ 横割れ検知装置
２１ 摩擦力演算手段
２３ 摩擦力変動係数演算手段
２５ 判定手段
２７ 操業条件変更手段
２９ ピンチコントローラ制御装置
３１ 変位計
DESCRIPTION OF SYMBOLS 1 Mold 3 Cast slab 5 Guide roller 7 Pinch roller 9 Pivot 11 Lever 13 Hydraulic cylinder 15 Hydraulic meter 15a Inlet side hydraulic meter 15b Outlet side hydraulic meter 17 Oscillation device 19 Lateral crack detection device 21 Friction force calculation means 23 Friction force fluctuation 23 Coefficient computing means 25 Judging means 27 Operating condition changing means 29 Pinch controller control device 31 Displacement meter
Claims (10)
前記横割れ検知方法によって横割れ発生の危険があると検知された場合には、前記摩擦力変動係数が前記閾値以下となるように操業条件を変更して連続鋳造することを特徴とする連続鋳造鋳片の製造方法。 A method for producing a continuous cast slab using the method for detecting transverse cracks in a continuous cast slab according to claim 1, 2 or 3,
Continuous casting, characterized in that when it is detected that there is a risk of lateral cracking by the lateral crack detection method, continuous casting is performed by changing operating conditions so that the coefficient of friction variation is equal to or less than the threshold value. A method for producing a slab.
前記横割れ検知方法によって横割れ発生の危険があると検知された場合には、製造された連続鋳造鋳片を検品し、横割れ部を手入れすることを特徴とする連続鋳造鋳片の製造方法。 A method for producing a continuous cast slab using the method for detecting transverse cracks in a continuous cast slab according to claim 1, 2 or 3,
When it is detected by the transverse crack detection method that there is a risk of occurrence of transverse cracks, the produced continuous cast slab is inspected and the transverse crack part is maintained, .
前記判定手段によって横割れ発生の危険があると判定されたときに、摩擦力変動係数を小さくするために操業条件を変更する操業条件変更手段を有し、
該操業条件変更手段は、鋳造速度を減速するようにピンチローラ制御装置を制御する及び／又は鋳型の振動振幅を小さくするように加振装置を制御することを特徴とする連続鋳造鋳片の製造装置。 An apparatus for producing a continuous cast slab comprising the transverse crack detection device for a continuous cast slab according to claim 7, 8 or 9,
When it is determined by the determination means that there is a risk of occurrence of lateral cracks, the operation condition change means for changing the operation condition to reduce the coefficient of frictional force variation,
The operation condition changing means controls the pinch roller control device so as to reduce the casting speed and / or controls the vibration device so as to reduce the vibration amplitude of the mold. apparatus.
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