JPS60177939A - Method for starting casting in continuous casting - Google Patents
Method for starting casting in continuous castingInfo
- Publication number
- JPS60177939A JPS60177939A JP3319184A JP3319184A JPS60177939A JP S60177939 A JPS60177939 A JP S60177939A JP 3319184 A JP3319184 A JP 3319184A JP 3319184 A JP3319184 A JP 3319184A JP S60177939 A JPS60177939 A JP S60177939A
- Authority
- JP
- Japan
- Prior art keywords
- recess
- casting
- immersion nozzle
- molten metal
- mold
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/08—Accessories for starting the casting procedure
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
Abstract
Description
【発明の詳細な説明】
この発明は連続鋳造を行なうにあたり鋳型内に溶融金属
を注渇し始める際の方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for starting to pour molten metal into a mold during continuous casting.
周知のように連続鋳造法は、溶融金属を鋳型に注湯する
とともに冷却して凝固シェルを生成し、凝固シェルを鋳
型から引き抜きつつ更に冷却して鋳片を得る方法であり
、歩留りや鋳片の品質あるいはエネルギー効率等の点で
造塊法に比較して優れている。しかしながら連鋳鋳片の
うち、鋳込み開始、取鍋やタンディツシュの交換あるい
は幅変更ざらには鋳込み終了などに相当する部分は、所
謂非定常部鋳片として表面および内部品質が劣る。As is well known, the continuous casting method is a method in which molten metal is poured into a mold and cooled to produce a solidified shell, and the solidified shell is pulled out of the mold and further cooled to obtain a slab. It is superior to the agglomeration method in terms of quality and energy efficiency. However, the parts of the continuous cast slab that correspond to the start of casting, the replacement of the ladle or tundish, the change of width, and the end of casting have poor surface and internal quality as so-called unsteady part slabs.
このような鋳片は、例えば鋼種組成として高級鋼向けに
鋳造した場合、その鋼種の品質特性を満足できず、その
結果低級鋼へ用途を変更したり、あるいは品質が特に劣
るときには廃片とせざるを得なくなったりし、いずれに
しても歩留りを低下させる原因となっている。特に鋳込
み開始時に相当する鋳片すなわち最ボトム鋳片にあって
は、表面欠陥や超音波探傷により検出される内部欠陥が
多く、従来、このような表面欠陥については表面手入れ
研削量を多くして対処し、また内部欠陥については、規
格を変更して他の用途に充当したり、あるいはボトムク
ロップの切り捨て山を異常に多くして廃片として処理し
たりして対処しており、そのため歩留りを著しく低下さ
せる一因となっている。For example, when such slabs are cast for high-grade steel, they cannot meet the quality characteristics of that steel type, and as a result, the use is changed to lower-grade steel, or if the quality is particularly poor, they have to be scrapped. In either case, this causes a decrease in yield. Particularly in the slab corresponding to the beginning of casting, that is, the bottom slab, there are many surface defects and internal defects detected by ultrasonic flaw detection. Conventionally, such surface defects are treated by increasing the amount of surface care grinding. Internal defects are also dealt with by changing the specifications and using them for other purposes, or by creating an abnormally large number of truncated bottom crops and disposing of them as scrap, which leads to lower yields. This is a contributing factor to the significant decline.
すなわち、鋳込開始時においては、溶融金属例えば溶鋼
が取鍋からタンディツシュへ、またタンディツシュから
鋳型へ注入される際に空気酸化をうけたり、またタンデ
ィツシュや鋳型に付着残存している酸化物をまき込んだ
りしてその清浄性が劣化し、これに加え鋳込開始時にお
いては溶鋼の温度が低下し易く、それに伴って溶鋼の粘
性が高くなるから、まき込んだ酸化物の浮上分離性が悪
くなり、その結果鋳込み開始に相当する部分にあっては
、酸化物を凝固鋳片内に取り込み、鋳片の品質が低下し
てしまう。このような問題を解消するために、従来では
、取鍋からタンディツシュへの注湯にロングノズルなど
を用いたり、鋳込み開始に先立ってタンディツシュおよ
び鋳型の内部をArガスなどの不活性ガスで置換したり
して溶鋼の酸化を防止する方法や、連続一連続鋳造を行
なう際の第1ヒートの溶鋼温度を第2ヒート以降での温
度に比較して高くする方法などが行なわれていた。しか
しながら不活性ガスによって非酸化雰囲気に設定する方
法では、設備の構造や操業が複雑かつ困難になるおそれ
があり、また鋳込み開始時の溶鋼温度を高くする方法で
は、溶鋼の粘性を低く維持できるものの、溶鋼の酸化を
防止し得す、しかも酸化物の凝固鋳片への取り込みは溶
鋼の粘性のみに起因するものではないから、内部欠陥を
必ずしも有効には防止することができない。That is, at the start of casting, when molten metal, such as molten steel, is poured from the ladle to the tundish and from the tundish to the mold, it may be oxidized in the air, or it may be contaminated with oxides that remain on the tundish or mold. In addition, the temperature of the molten steel tends to drop at the start of pouring, and the viscosity of the molten steel increases accordingly, making it difficult to float and separate the mixed oxides. As a result, in the portion corresponding to the start of casting, oxides are taken into the solidified slab and the quality of the slab deteriorates. In order to solve these problems, conventional methods have been to use a long nozzle to pour the metal from the ladle into the tundish, or to replace the inside of the tundish and mold with an inert gas such as Ar gas before starting casting. Methods have been used to prevent oxidation of molten steel, and methods to increase the temperature of molten steel in the first heat during continuous casting compared to the temperatures in the second and subsequent heats. However, the method of setting a non-oxidizing atmosphere using inert gas may complicate and difficult the structure and operation of the equipment, and the method of increasing the temperature of molten steel at the start of pouring can maintain the viscosity of molten steel at a low level. Although oxidation of molten steel can be prevented, internal defects cannot necessarily be effectively prevented because the incorporation of oxides into solidified slabs is not caused only by the viscosity of molten steel.
また従来、設備の改造を必要とせずに鋳片品質の低下を
可及的に防止し得る方法として、鋳込み開始時における
空気酸化をうける時間を短くする方法が知られている。Furthermore, as a method for preventing deterioration in slab quality as much as possible without requiring modification of equipment, a method of shortening the time during which slabs are exposed to air oxidation at the start of casting has been known.
すなわち第1図に示すように、鋳込みを開始するに際し
、鋳型1内の鋼浴2の湯面が浸漬ノズル3の先端吐出口
4を越えるまではパウダの装入を行なうことができない
から、注湯開始からパウダ装入までの間では溶鋼が空気
に触れて酸化をうける。したがってこのような酸化時間
を短くするために、浸漬ノズル3の下端部をダミーパー
5の上端部に出来るだけ近づけて注湯を開始すれば、溶
鋼の酸化が少なくなるために、酸化物のまき込みによる
品質の低下をある程度防止することができる。しかしな
がら、溶鋼はダミーパー5に接触すると熱を奪われて凝
固するから、ダミーパー5と浸漬ノズル3とが接近しす
ぎた場3−
合には、浸漬ノズル3がダミーパー5に付着して鋳込み
を行なえなくなることがあり、したがって浸漬ノズル3
の下端部をダミーパー5に接近させるにも限度があって
、両者の間にはある程度の距離を確保せざるを得ず、そ
のため鋳込み開始時に浸漬ノズル3をダミーパー5に接
近させて注湯を行なうとしても、最ボトム鋳片の品質が
低下するとともに、表面手入れ研削量やクロップ切捨量
が多く、歩留り低下を避けられないのが実情である。That is, as shown in FIG. 1, when starting casting, powder cannot be charged until the level of the steel bath 2 in the mold 1 exceeds the tip discharge port 4 of the immersion nozzle 3. From the time the hot water starts until the powder is charged, the molten steel is exposed to air and undergoes oxidation. Therefore, in order to shorten the oxidation time, if pouring is started with the lower end of the immersion nozzle 3 as close as possible to the upper end of the dummy par 5, oxidation of the molten steel will be reduced, and the oxides will not be mixed in. This can prevent quality deterioration to some extent. However, when the molten steel comes into contact with the dummy par 5, it loses heat and solidifies, so if the dummy par 5 and the immersion nozzle 3 are too close, the immersion nozzle 3 will stick to the dummy par 5 and casting will not be possible. may run out, therefore the submerged nozzle 3
There is a limit to how close the lower end can be to the dummy par 5, and a certain distance must be maintained between the two, so when pouring starts, the immersion nozzle 3 is brought close to the dummy par 5 to pour the metal. However, the reality is that the quality of the bottom slab deteriorates, the amount of surface care grinding and the amount of cropping are large, and a decrease in yield cannot be avoided.
この発明は上記の事情に鑑みてなされたもので、最ボト
ム鋳片の表面および内部欠陥の発生を防止することによ
り歩留りの向上を図ることのできる連続鋳造におCプる
鋳込み開始方法を提供することを目的とするものである
。そしてこの発明は、鋳込み開始の際に鋳型の内部に挿
入しておくダミーパーの上端部に、浸漬ノズルの先端部
を収容可能な凹部を形成しておき、その凹部内に浸漬ノ
ズルの先端吐出口を位置させた状態で溶融金属の注湯を
始めることを特徴とするものである。This invention has been made in view of the above circumstances, and provides a casting start method for continuous casting that can improve the yield by preventing the occurrence of surface and internal defects in the bottommost slab. The purpose is to In addition, in this invention, a recess capable of accommodating the tip of the immersion nozzle is formed at the upper end of the dummy par that is inserted into the inside of the mold at the start of casting, and the tip discharge port of the immersion nozzle is placed in the recess. The feature is that pouring of molten metal starts with the molten metal placed in the position.
以下この発明を更に詳細に説明する。This invention will be explained in more detail below.
4−
第2図ないし第5図はこの発明の方法を実施する状況を
示す略解図であって、鋳型10内にダミーパー11の上
端部を挿入するとともに、鋳型10の上方からはタンデ
ィツシュ(図示せず)に取付けた浸漬ノズル12を挿入
する。そのダミーパー11の上端部で幅方向の中央部に
は、浸漬ノズル12の先端部を収容可能な凹部13を形
成しておく。その凹部13は、短時間で浸漬ノズル12
における先端吐出口14を鋼浴中に埋没させるためのも
のであって、その形状および大きさは、浸漬ノズル12
の吐出口14を内部に位置させることができるとともに
、浸漬ノズル12が付着しないよう内壁面と浸漬ノズル
12との間に充分な間隔があり、さらに上向きの溶鋼流
が生じるよう上方に向けて拡がった所謂上広型となるよ
う設定しておく。したがって凹部13は、第3図に示す
ような外周面側に吐出口14が開口する浸漬ノズル12
の場合には、ある程度深くする必要があるが、下端面に
開口する単純な円筒型の浸漬ノズルの場合には、浅くす
ることができる。4- FIGS. 2 to 5 are schematic diagrams showing the situation in which the method of the present invention is carried out, in which the upper end of the dummy par 11 is inserted into the mold 10, and a tundish (not shown) is Insert the immersion nozzle 12 attached to the At the upper end of the dummy par 11 and at the center in the width direction, a recess 13 is formed in which the tip of the immersion nozzle 12 can be accommodated. The recess 13 can be used for the immersion nozzle 12 in a short time.
This is for immersing the tip discharge port 14 in the steel bath, and its shape and size are similar to those of the immersion nozzle 12.
The discharge port 14 can be located inside, there is a sufficient distance between the inner wall surface and the immersed nozzle 12 so that the immersed nozzle 12 does not stick to it, and the molten steel is expanded upward to generate an upward flow of molten steel. It is set to be a so-called upper wide type. Therefore, the recess 13 serves as an immersion nozzle 12 with a discharge port 14 opened on the outer peripheral surface side as shown in FIG.
In this case, it is necessary to make the nozzle deep to some extent, but in the case of a simple cylindrical submerged nozzle that opens at the bottom end surface, it can be made shallow.
注iを開始するに先立って、浸漬ノズル12の先端吐出
口14をダミーバー11における凹部13内に位置させ
ておく。その場合、鋳型10とタンディツシュとの間隔
が一定距離に設定されているから、従来一般に使用され
ている長さの浸漬ノズル12を用いるとすれば、吐出口
14を前記凹部13内に位置させるためには、ダミーバ
ー11を従来の場合より凹部13の深さ分上方に引き上
げる。ダミーバー11と浸漬ノズル12との相対位置を
上記のように設定した後に注湯を開始する。Prior to starting the injection, the tip outlet 14 of the immersion nozzle 12 is positioned within the recess 13 in the dummy bar 11. In that case, since the distance between the mold 10 and the tundish is set to a certain distance, if the immersion nozzle 12 of the length commonly used in the past is used, the discharge port 14 will be located within the recess 13. To do this, the dummy bar 11 is pulled upward by the depth of the recess 13 compared to the conventional case. After the relative positions of the dummy bar 11 and the immersion nozzle 12 are set as described above, pouring is started.
溶融金属は先ず前記凹部13内に流れ出してここを満し
、ついで鋳型10の内部全体に広がるが、凹部13の容
積が小さいから、浸漬ノズル12の吐出口14は速やか
に銅浴内に埋没し、したがって浸漬ノズルから吐出する
溶融金属の空気酸化をうける比率が著しく低減し、これ
に加え吐出口14が鋼浴中に埋没すればパウダーを添加
できるから、従来に比較して相当早い時期にパウダーを
添加でき、したがってクロップ以降の鋳片に相当する溶
鋼の鋳型10内での空気酸化を有効に防止できる。なお
、注湯開始当初の溶鋼すなわちクロップに相当する溶鋼
は、空気酸化や鋳型10内での汚染等初期酸化をうける
が、前記凹部13が所謂上広型で上向きの溶鋼流が生じ
ること、パウダーを早期添加できること等により、酸化
生成物は浮上分前し易く、以降の鋼浴中に滞留する割合
が少なく、その結果酸化生成物の取り込みによる内部欠
陥の発生度合を低減できる。The molten metal first flows into the recess 13 and fills it, and then spreads throughout the inside of the mold 10, but since the volume of the recess 13 is small, the discharge port 14 of the immersion nozzle 12 is quickly buried in the copper bath. Therefore, the rate at which the molten metal discharged from the immersion nozzle undergoes air oxidation is significantly reduced, and in addition, powder can be added by submerging the discharge port 14 in the steel bath, so powder can be added at a much earlier stage than in the past. Therefore, it is possible to effectively prevent air oxidation of molten steel corresponding to slabs after cropping in the mold 10. Note that the molten steel at the beginning of pouring, that is, the molten steel corresponding to the crop, undergoes initial oxidation such as air oxidation and contamination within the mold 10, but the concave portion 13 is so-called wide-shaped and an upward molten steel flow occurs, and powder By being able to add oxidation products at an early stage, the oxidation products are easily floated, and the proportion of subsequent retention in the steel bath is small, and as a result, the degree of occurrence of internal defects due to the incorporation of oxidation products can be reduced.
他方、早い時期に添加したパウダーは、上広型の凹部1
3により上向きの溶鋼流が生じることに伴って、従来と
同等もしくはそれ以上に速ヤかに溶融し、したがってパ
ウダーの溶融層の形成を迅速化できるから、所謂ノロカ
ミ等による表面欠陥を低減できる。On the other hand, the powder added at an early stage is
As a result of 3, an upward flow of molten steel is generated, melting occurs as quickly as or faster than conventional methods, and therefore the formation of a molten layer of powder can be speeded up, so surface defects such as so-called slag can be reduced.
このように上記の方法では、鋳込み開始時に相当する鋳
片すなわち最ボトム鋳片を鋳造する際の酸化やその表面
および内部欠陥を従来よりも大幅に低減できるから、表
面手入れ研削量や廃片とすべき量が減り、その結果歩留
りを向上することができる。In this way, the above method can significantly reduce oxidation and surface and internal defects when casting the slab corresponding to the start of casting, that is, the bottom slab, compared to the conventional method, so it is possible to reduce the amount of surface care grinding and the amount of scrap. The amount to be processed is reduced, and as a result, the yield can be improved.
7一 つぎにこの発明の実施例を記す。71 Next, examples of this invention will be described.
実 施 例
5US304鋼を連続鋳造するに際し、ダミーバーおよ
び浸漬ノズルを第2図ないし第5図に示す状態に設定し
、200mIB×1l100II1ノスラフを鋳造した
。得られた最ボトムスラブの表面および内部品質につい
て、従来方法で得た従来品と比較した。品質調査は、ス
ラブ表面からの厚さ方向の殺剤試験によるマクロ欠陥発
生状況、および製品板における表面品質指数で比較した
。結果は第6図および第7図に示す通りであって、第6
図にスラブ殺剤試験による調査結果を示し、第7図に製
品板での表面品質指数を従来品の品質指数を1として示
す。Example 5 When continuously casting US304 steel, the dummy bar and the immersion nozzle were set as shown in Figs. 2 to 5, and 200 mIB x 1 l, 100 II, and 1 Noslav was cast. The surface and internal quality of the obtained bottom slab was compared with that of a conventional product obtained by a conventional method. In the quality investigation, we compared the occurrence of macro defects through a pesticide test in the thickness direction from the slab surface, and the surface quality index of the product board. The results are shown in Figures 6 and 7.
Figure 7 shows the results of the slab-killing test, and Figure 7 shows the surface quality index of the product board, with the quality index of the conventional product set at 1.
これらの図から明らかなように、この発明の方法によれ
ばスラブ表面欠陥指数を従来方法に比較して著しく改善
でき、スラブ表面研削量が大幅に低減した。また製品板
における表面品質指数も従来方法に比較して約60%改
善され、製品歩留りが著しく向上した。このようにこの
発明の方法で8−
は、実用1優れた効果を得られることが認められた。As is clear from these figures, according to the method of the present invention, the slab surface defect index was significantly improved compared to the conventional method, and the amount of slab surface grinding was significantly reduced. Furthermore, the surface quality index of the product plate was improved by about 60% compared to the conventional method, and the product yield was significantly improved. As described above, it has been confirmed that the method of the present invention can produce excellent effects in practical use.
以上説明したようにこの発明の方法によれば、ダミーバ
ーの上端部に形成した凹部の内部に、浸漬ノズルの先端
吐出口を位置させて注湯を開始することにより、溶融金
属の初期酸化やそれに伴う表面および内部欠陥の発生を
大幅に低減できるから、表面手入れ研削量や廃材どすべ
き部分が少なくなり、その結果歩留りを向上させること
ができる。As explained above, according to the method of the present invention, by starting pouring by positioning the tip outlet of the immersion nozzle inside the recess formed at the upper end of the dummy bar, initial oxidation of the molten metal can be prevented. Since the occurrence of accompanying surface and internal defects can be greatly reduced, the amount of surface care grinding and the amount of waste material to be disposed of are reduced, and as a result, the yield can be improved.
第1図は従来の鋳込み開始方法を説明するための鋳型の
断面図、第2図ないし第5図はこの発明の詳細な説明す
るための略解図であって、第2図は鋳型の平面視図、第
3図は第2図のI[1−III線矢視図、第4図は第2
図のIV −IV線矢視図、第5図は第2図のv−vm
矢視図、第6図は本発明方法および従来方法によって得
たスラブについての殺剤試麟による調査結果を示す線図
、第7図は本発明方法および従来方法によって得たスラ
ブにつぃての表面品質指数を従来品の品質指数を1とし
て示す図である。
10−9.鋳型、 11・・・ダミーバー、 12・・
・浸漬ノズル、 13・・・凹部、 14・・・吐出口
。
出顆人 川崎製鉄株式会社
代理人 弁理士 豊田武久
(ばか1名)
11−
1譬W≧埠4L4γ
r’1 −
〇 −FIG. 1 is a sectional view of a mold for explaining a conventional casting start method, FIGS. 2 to 5 are schematic views for explaining the present invention in detail, and FIG. 2 is a plan view of the mold. Figure 3 is a view taken along the line I[1-III in Figure 2, and Figure 4 is a view of the
IV-IV line arrow view of the figure, Figure 5 is v-vm of Figure 2.
6 is a line diagram showing the results of investigation using a pesticide test on slabs obtained by the method of the present invention and the conventional method, and FIG. FIG. 3 is a diagram showing the surface quality index of the conventional product, with the quality index of the conventional product being 1. 10-9. Mold, 11...Dummy bar, 12...
- Immersion nozzle, 13... recess, 14... discharge port. Representative of Kawasaki Steel Co., Ltd. Patent attorney Takehisa Toyota (1 idiot) 11-1 example W≧Bu4L4γ r'1 - 〇 -
Claims (1)
始するにあたり、浸漬ノズルの先端部を収容可能な凹部
をダミーバーの上端部に形成しておき、浸漬ノズルの先
端吐出口をその凹部内に位置させた状態で溶融金属を注
湯することを特徴とする連続鋳造における鋳込み開始方
法。Before inserting the dummy bar into the mold and starting casting into the mold, a recess capable of accommodating the tip of the immersion nozzle is formed at the upper end of the dummy bar, and the tip outlet of the immersion nozzle is inserted into the recess. A method for starting pouring in continuous casting, characterized by pouring molten metal in a position.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3319184A JPS60177939A (en) | 1984-02-23 | 1984-02-23 | Method for starting casting in continuous casting |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3319184A JPS60177939A (en) | 1984-02-23 | 1984-02-23 | Method for starting casting in continuous casting |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS60177939A true JPS60177939A (en) | 1985-09-11 |
Family
ID=12379590
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP3319184A Pending JPS60177939A (en) | 1984-02-23 | 1984-02-23 | Method for starting casting in continuous casting |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS60177939A (en) |
-
1984
- 1984-02-23 JP JP3319184A patent/JPS60177939A/en active Pending
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