JP2004034094A

JP2004034094A - Mold for continuous casting

Info

Publication number: JP2004034094A
Application number: JP2002194880A
Authority: JP
Inventors: Yuichi Ogawa; 小川　勇一
Original assignee: Mishima Kosan Co Ltd
Current assignee: Mishima Kosan Co Ltd
Priority date: 2002-07-03
Filing date: 2002-07-03
Publication date: 2004-02-05
Anticipated expiration: 2022-07-03
Also published as: JP4227768B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for continuous casting which enables the production of a slab provided with satisfactory quality by making the shape of the cooling face in a mold body on a hot time into the prescribed one. <P>SOLUTION: In the mold 10 for continuous casting, molten steel 12 poured into a surrounded mold space 11 is cooled and solidified to produce a slab. The inside part of a mold body 14 lying in a position lower than a meniscus part 13, and brought into contact with the upper part of the molten steel 12 has been provided with an extension part 15 which substantially coincides with the expansion margin of the mold body 14 on production, so that the surface condition of the slab to be produced can be made satisfactory, the product quality can be improved, and further, the possibility of the occurrence of breakout or the like in the slab can be reduced. Thus, the mold 10 for continuous casting which can also deal with high speed casting can be provided. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、鋳造中の鋳型の熱変形を考慮した連続鋳造用鋳型に関する。
【０００２】
【従来の技術】
従来、連続鋳造設備で使用される連続鋳造用鋳型（以下、単に鋳型とも言う）７０は、図５に示すように、一対の幅狭冷却部材である短辺部材７１、７２と、この短辺部材７１、７２を挟み込むように配置される一対の幅広冷却部材である長辺部材７３、７４とを備え、この向い合う長辺部材７３、７４の両端部にそれぞれボルト７５を取付け、バネ（図示しない）を介してナット７６で固定した構成となっている。
この短辺部材７１、７２は鏡面対称で同じ構成となっており、裏面側の上下方向に多数の導水溝が設けられた短辺銅板７７と、短辺銅板７７の裏面側にボルトによって固定されたバックプレート７８（冷却箱とも言う）とを有している。そして、バックプレート７８の上端部及び下端部にそれぞれ設けられた排水部及び給水部を介して導水溝に冷却水の一例である工業用水を流すことで、短辺銅板７７の冷却を行っている。一方、長辺部材７３、７４も略同じ構成となっているが、長辺部材７３、７４の長辺銅板７９の幅は、短辺部材７１、７２の短辺銅板７７の幅より長く、この長辺銅板７９の裏面側にそれぞれ固定されたバックプレート８０の幅が、長辺銅板７９の幅より長くなっている。
なお、この短辺部材７１、７２の短辺銅板７７と、長辺部材７３、７４の長辺銅板７９とで鋳型本体８１が構成されている。また、この鋳型本体８１の内側（冷却面側）の形状は、製造する鋳片の体積収縮に対応した形状となっており、長辺銅板７９の内側対向面８２の距離は、図６の二点鎖線に示すように、鋳型本体８１の上端から下端にかけて狭くなっている。
【０００３】
連続鋳造作業時においては、上記した鋳型７０の上方（短辺部材７１、７２、長辺部材７３、７４の上側）から溶鋼を注ぎ、この鋳型７０により製品となる鋳片の初期凝固を行い、凝固した鋳片を鋳型７０下方より一定速度で連続して引抜いて製造している。このとき、鋳型７０を鋳片に対して、上下方向へ例えば１０ｍｍの範囲で１５０回／ｍｉｎ程度振動（モールドオシレーションとも言う）させているので、鋳型７０は鋳片に対して相対運動をし、鋳型７０が鋳片より下がったり上がったりしている。これにより、鋳型７０が鋳片に対して下がった場合は、短辺銅板７７の内側対向面８３及び長辺銅板７９の内側対向面８２で構成される冷却面（鋳片との接触面）と鋳片の凝固殻（凝固シェル）との間に隙間が発生し、また上がった場合は、鋳型７０が鋳片に対して押し付けられる。
なお、鋳型７０に注がれる溶鋼温度及び鋳型７０出口の鋳片の表面温度は操業条件により異なるが、通常、溶鋼温度は約１５００℃程度であり、鋳型７０出口の鋳片の表面温度は８００〜１２００℃である。ここでの鋳片の内部は未凝固状態、即ち液体状態となっている。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記した連続鋳造用鋳型７０には、以下の問題がある。
鋳型本体８１の冷却面は、例えば２００〜３００℃程度に冷却されているが、図７に示すように、鋳型本体８１の上端部から下端部にかけて温度分布が生じ、特に鋳型本体８１の上部の温度が他の部分の温度より高くなっている。このため、図６の実線に示すように、鋳型本体８１が溶鋼及び鋳片の熱によって熱膨張（熱変形）し、特に鋳型本体８１の内側上部が中央部及び下部の冷却面上より、鋳型本体８１の内側へ大きく突出し変形することとなる。
このように、鋳型本体８１の内側上部に突出部が発生することで、鋳型本体８１の冷却面と鋳片の表面とが略平行にならない。このため、前記したように、鋳片に対して鋳型７０を相対運動させた場合、突出部が鋳片の表層部に形成される凝固殻を押し付け変形させるので、製造する鋳片の品質を悪化させる問題がある。また、突出部が凝固殻を押し付けた場合、凝固殻が破れ、再度鋳型７０の冷却によって修復される場合もあるが、このとき鋳片の表面にラップ傷等が発生し、製品品質を悪くする問題もある。そして、これに起因した鋳片のブレークアウト等を招来する可能性もある。
更に、近年、連続鋳造作業の能率を向上させるため、鋳造速度が上昇しているが、特に、多くの連続鋳造設備で採用されている鋳片厚みの１／３〜１／２程度の鋳片厚みの鋳型を備えた連続鋳造機が出現するに至って、従来と比較して２倍、３倍の鋳造速度が採用される場合も見られるようになった。このように鋳造速度が速くなると、鋳型本体に抽出される熱量が比例的に増大するので、鋳型本体での熱変形がより顕著に現れてきた。
本発明はかかる事情に鑑みてなされたもので、熱間時における鋳型本体の冷却面の形状を所定の形状にすることで、良好な品質を備えた鋳片を製造可能な連続鋳造用鋳型を提供することを目的とする。
【０００５】
【課題を解決するための手段】
前記目的に沿う本発明に係る連続鋳造用鋳型は、囲まれた鋳型空間に投入された溶鋼を冷却して凝固させ鋳片を製造する連続鋳造用鋳型において、メニスカス部より下位置にあって、溶鋼上部が接する鋳型本体の内側部分に、製作時に、鋳型本体の膨張代に実質的に一致する拡幅部が設けられている。このように、制作時において鋳型本体の内側部分に拡幅部を設けるので、熱間時に鋳型本体が熱によって膨張した場合でも、鋳型本体の内側部分の冷却面を所定の形状、例えば実質的に平面状態（１段テーパ）にできる。
ここで、本発明に係る連続鋳造用鋳型において、製作時に、拡幅部の上側に、更に拡幅部の内幅と同一又はより広い拡大拡幅部を設けることが好ましい。このように、拡幅部の上側に、更に拡幅部の内幅と同一又はより広い拡大拡幅部を設けるので、鋳型本体の冷却面の全てを、鋳型本体の熱変形を考慮した形状に加工する必要がなくなる。
【０００６】
本発明に係る連続鋳造用鋳型において、製作時に、メニスカス部の上側に、更に拡幅部の内幅と同一又はより広い拡大拡幅部を設けることが好ましい。このように、メニスカス部の上側に、更に拡幅部の内幅と同一又はより広い拡大拡幅部を設けるので、例えば溶鋼と接触しない部分の冷却面の形状を単純にできる。
本発明に係る連続鋳造用鋳型において、膨張代は予測計算値を用いて求めることが好ましい。このようにして、熱間時における鋳型本体の膨張代を求めるので、拡幅部の形状を容易に把握できる。
【０００７】
【発明の実施の形態】
続いて、添付した図面を参照しつつ、本発明を具体化した実施の形態につき説明し、本発明の理解に供する。
ここに、図１は本発明の一実施の形態に係る連続鋳造用鋳型の説明図、図２は同連続鋳造用鋳型の拡幅部の形状を求めるための予測計算値を示すグラフ、図３は同予測計算値を加工した説明図、図４（Ａ）、（Ｂ）はそれぞれ変形例に係る鋳型本体の説明図である。
【０００８】
図１に示すように、本発明の一実施の形態に係る連続鋳造用鋳型１０は、数値解析を行うための形状を示したものであり、囲まれた鋳型空間１１に投入された溶鋼１２を冷却して凝固させ鋳片（図示しない）を製造するものである。この連続鋳造用鋳型１０は、メニスカス部１３より下位置にあって、溶鋼１２上部が接する鋳型本体１４の内側部分に、製作時に鋳型本体１４の膨張代に実質的に一致する拡幅部１５が設けられている。なお、拡幅部１５とは、鋳型本体１４によって形成される鋳型空間１１の拡幅部分を意味するもので、鋳型本体１４に対しては、制作時において、鋳型本体１４の冷却面から例えば、０．１〜０．５ｍｍ程度の深さを有する窪み形状となったものである。以下、詳しく説明する。
【０００９】
連続鋳造用鋳型１０は、前記したように、一対の幅狭冷却部材である短辺部材と、一対の幅広冷却部材である長辺部材とを組合せることで製造されるものである（図５参照）。また、連続鋳造用鋳型１０の長辺部材は、熱伝導性が良好な金属の一例である銅からなり、裏面側に通水部が設けられた長辺銅板１６と、長辺銅板１６の裏面側に取付け手段の一例であるボルトによって固定された支持部材の一例であるバックプレート（冷却箱、水箱とも言う）とを有し、バックプレートに設けられた給水部及び排水部を介して通水部に冷却水の一例である工業用水を流すことで長辺銅板１６の冷却を行うものである。なお、連続鋳造用鋳型１０の短辺部材も、上記した長辺部材と略同様の構成であり、長辺部材の長辺銅板１６と短辺部材の短辺銅板とで鋳型本体１４が構成されている。これにより、平面視した鋳型本体１４の中央部に鋳型空間１１が形成されることとなる。
【００１０】
鋳型本体１４を構成する長辺銅板１６及び短辺銅板の上端から下端までの垂直長さＬは、例えば７００〜１０００ｍｍ程度であり、その厚みが例えば１０〜５０ｍｍ程度である。また、長辺銅板１６の幅（短辺銅板の幅も同様）は、上端部から下端部へかけて短くなっているため、一対の長辺部材の長辺銅板１６の内側対向面１７、及び一対の短辺部材の短辺銅板の内側対向面とで構成される内周長は、鋳型本体１４の上端部より下端部の方が短くなっている。これは、例えば、凝固収縮、固体収縮等の鋳片の体積収縮を考慮して決定されるもので、その数値は、過去の実績データや、鋳片の線膨張量及び温度を基に決定することが好ましい。
【００１１】
鋳型本体１４の長辺銅板１６の上部には、長辺銅板１６の幅方向に渡って溝状となった拡幅部１５が設けられている。この拡幅部１５は、長辺銅板１６の上部（上部領域）の下側から中央部へかけて徐々に拡幅し、また中央部から上側へかけて、徐々に縮幅するものである。なお、短辺銅板についても同様である。
ここで、鋳型本体１４の内側に設けた拡幅部１５の形状の求め方について、長辺銅板１６を用いて説明する。
まず、制作時における鋳型本体の長辺銅板の内側を平面（１段テーパとも言う）状と仮定した（基準テーパ）場合、熱間時（溶鋼１２投入中）においては、長辺銅板の内側の形状が、例えば図６の二点鎖線の状態から実線の状態まで熱変形する（膨張代を示す）。なお、このときの長辺銅板の内側形状の予測計算値は、例えば、鋳片の引き抜き速度、鋳型本体（長辺銅板）の厚み、冷却速度等を用い、従来公知の有限要素法（ＦＥＭ）によって求めることができる。この予測計算した結果を図２に示す。なお、長辺銅板上端からの距離が１００ｍｍの位置が、溶鋼の湯面（液面）の位置に相当する。
この基準テーパは、長辺銅板上端からの距離と、高さ方向の各位置の変位量とが比例関係を示すことから分かるように、長辺銅板の上端から下端へかけ、鋳片の体積収縮を考慮して連続的に傾斜している。しかし、熱間時における長辺銅板の形状（銅板表面プロフィール）は、溶鋼の湯面近傍の変位量が大幅に増加していることから、湯面近傍で大幅な熱変形が起こることが予測できる。
【００１２】
また、図２のデータを基に、長辺銅板の高さ方向の各部分における傾きを求めた結果を図３に示す。なお、傾きは、長辺銅板を高さ方向に１０ｍｍ毎に区分した場合の各区間部分での長辺銅板間距離に対する変化の割合を１ｍ当りの値に換算したもので、以下の式によって示される。
傾き［％／ｍ］＝（Ｗ１−Ｗ２）／Ｗ３×１００×（１０００／１０）
ここで、Ｗ１は各部分の上端の位置で対向する長辺銅板間の距離、Ｗ２は各部分の下端の位置で対向する長辺銅板間の距離、Ｗ３は長辺銅板の下端の位置で対向する長辺銅板間の距離をそれぞれ意味する（図６参照）。
【００１３】
基準テーパは、長辺銅板の上端から下端へかけ、鋳片の体積収縮を考慮して連続的に傾斜しているので、図３に示すように、長辺銅板の上端から下端へかけての各部分の傾きは略一定値（０．４％／ｍ程度）となっている。しかし、熱間時における長辺銅板（銅板表面プロフィール）は、溶鋼の湯面（液面）近傍の傾きが大きく増減していることから、湯面近傍で大幅な熱変形が起こることが予測できる。なお、長辺銅板上端からの距離が４５０ｍｍの位置では、傾きが基準テーパと略近い数値となっている。従って、長辺銅板上端からの距離が４５０ｍｍ以上の位置では、長辺銅板の熱変形をほとんど考慮することなく、鋳片の体積収縮の影響を主として考慮することが好ましい。
【００１４】
前記したことから、溶鋼１２の熱影響を最も受け易い鋳型本体１４の内側上部に拡幅部１５を設け、中央部及び下部の形状を従来の形状とすることで、鋳型の熱変形を考慮した連続鋳造用鋳型１０を製造できる。
従って、拡幅部１５の形状は、長辺銅板上端からの各距離において、銅板表面プロフィールの数値から基準テーパの数値の差分に相当する深さ分だけ、基準テーパの面より鋳型本体１４側へ例えば削り込むことで、長辺銅板１６の内側に拡幅部１５を設けることができる。即ち、図２において、銅板表面プロフィールの線を、基準テーパの実線を中心として線対称とした線が、求める拡幅部１５の形状となる（図１の実線）。
このデータに基づき、長辺銅板をＮＣ工作機械を用いて加工することで、拡幅部１５を設けた長辺銅板１６を製造する。なお、この加工は、長辺銅板１６に対して連続的、又は所定間隔（例えば、１〜１０ｍｍ程度）毎に断続的に行うことも可能である。
【００１５】
これにより、連続鋳造作業の熱間時においては、連続鋳造用鋳型１０が溶鋼１２の熱で膨張することで、長辺銅板１６の形状が、図１の実線から二点鎖線へと熱変形する。従って、熱間時においては、溶鋼１２の熱影響による膨張代分だけ長辺銅板１６の拡幅部１５が膨張するので、鋳型本体１４の内側の形状が、実質的に目的とする所定形状（１段テーパ）となる。これにより、鋳型本体１４の冷却面と鋳片の表面とを略平行にできる。
なお、長辺銅板１６上端からの各距離において、銅板表面プロフィールの数値から基準テーパの数値の差分に相当する深さの拡幅部１５を設ける場合、拡幅部１５を設ける部分の長辺銅板１６の厚みが変化する。これにより、鋳型本体１４の膨張代も変化する。従って、この厚みを考慮して前記した有限要素法を用いて予測計算し、長辺銅板１６の内側形状を決定することで、より熱変形に対応した拡幅部１５を長辺銅板１６に設けることができる。
【００１６】
次に、連続鋳造用鋳型１０の変形例について、鋳型本体の長辺銅板を用いて説明するが、短辺銅板も同様であり、また鋳型本体の大きさや素材等は、前記した連続鋳造用鋳型１０と同じであるため、詳しい説明を省略する。
図４（Ａ）に示すように、鋳型本体２０は、製作時に、長辺銅板２１の上部に設けた拡幅部２２の上側に、更に拡幅部２２の内幅と同一の拡大拡幅部２３を設けたものである。従って、長辺銅板２１に設けた拡幅部２２の内幅が最も広い位置Ｘから、長辺銅板２１の上端２４へかけては、同じ内幅となっている。なお、拡幅部２２は、拡幅部１５の上側の形状が異なること以外、拡幅部１５と実質的に同一のものである。
【００１７】
また、位置Ｘから長辺銅板２１の下端２５へかけての長辺銅板２１の形状は、連続鋳造用鋳型１０と同じ形状である。これにより、長辺銅板２１の中で最も熱の影響を受け易い湯面近傍の部分を鋳片側へ突出することを確実に防止できると共に、長辺銅板２１の冷却面の全てを、長辺銅板２１の熱変形を考慮した形状に加工する必要がなくなる。
なお、拡幅部２２の上側には、長辺銅板２１の上端２４へかけて、拡幅部２２の内幅より徐々に広くなる拡大拡幅部２６を設けることも可能である（図４（Ａ）中の二点鎖線）。これにより、長辺銅板２１に対する拡幅部２２の加工が容易となり、作業性が更に良好となる。
【００１８】
図４（Ｂ）に示すように、鋳型本体３０は、製作時に、長辺銅板３１のメニスカス部３２の上側に、更に拡幅部３３の湯面位置Ｙの内幅と同一の拡大拡幅部３４を設けたものである。従って、長辺銅板３１の湯面位置Ｙから、長辺銅板３１の上端３５へかけては、同じ内幅となっている。なお、拡幅部３３は、拡幅部１５の上側の形状が異なること以外、拡幅部１５と実質的に同一のものである。
また、湯面位置Ｙから長辺銅板３１の下端３６へかけての長辺銅板３１の形状は、連続鋳造用鋳型１０と同じ形状である。これにより、溶鋼と接触しない部分の冷却面の形状を単純にできるので、長辺銅板３１の加工を容易にできる。
なお、メニスカス部３２の上側には、長辺銅板３１の上端３５へかけて、湯面位置Ｙの内幅より徐々に広くなる拡大拡幅部３７を設けることも可能である（図４（Ｂ）中の二点鎖線）。
【００１９】
以上、本発明を、実施の形態を参照して説明してきたが、本発明は何ら上記した実施の形態に記載の構成に限定されるものではなく、特許請求の範囲に記載されている事項の範囲内で考えられるその他の実施の形態や変形例も含むものである。例えば、前記した実施の形態や変形例の一部又は全部を組合せて本発明の連続鋳造用鋳型を構成する場合にも本発明は適用される。
また、前記実施の形態においては、平断面視して矩形の開口部を備えた鋳型本体を有する連続鋳造用鋳型を使用した場合について説明したが、平断面視した開口部の形状を、製造する鋳片の断面形状に対応させて、例えば多角形（例えば、凸形、凹形、６角形、８角形等）、円形、楕円形等とすることも勿論可能である。
【００２０】
そして、前記実施の形態においては、連続鋳造用鋳型として一対の長辺部材と一対の短辺部材とを組合せた組立鋳型を用いた場合について説明した。しかし、例えば、銅製のチューブを、導水溝を備えたハウジングに収納するチューブラ鋳型や、鋳造又は鍛造した銅ブロックに導水溝を穿孔したブロック鋳型等についても、本発明は適用される。なお、このように連続鋳造用鋳型として使用する鋳型の種類を変化させることで、例えば、スラブ（例えば、幅が１０００〜２５００ｍｍ程度、厚みが２００〜３００ｍｍ程度）、ブルーム（例えば、幅及び厚みが２００〜４００ｍｍ程度）、ビレット（例えば、幅及び厚みが１００〜２００ｍｍ程度）、ビームブランク（Ｈ型鋼用に使用）等の鋳片をそれぞれ製造することが可能となる。
更に、前記実施の形態においては、鋳型本体の内側の冷却面の形状を１段テーパとした場合について説明したが、他の形状でもよく、例えば従来公知の２段テーパ、マルチテーパ等とすることも可能である。
【００２１】
【発明の効果】
請求項１〜４記載の連続鋳造用鋳型においては、制作時において鋳型本体の内側部分に拡幅部を設けるので、熱間時に鋳型本体が熱によって膨張した場合でも、鋳型本体の内側部分の冷却面を所定の形状、例えば実質的に平面状態にできる。これにより、溶鋼の熱によって冷却面の一部に生じる溶鋼側への突出部の発生を防止できるので、従来のような突出部と鋳片の凝固殻との接触を防止できる。従って、製造する鋳片の表面状態を良好とし、製品品質を向上できると共に、鋳片のブレークアウト等の発生の可能性を低減できる。また、鋳造速度が上昇した場合においても、鋳型本体が熱変形した場合の形状を予め求めることで、鋳型本体の膨張代に応じて拡幅部を設けることができるので、高速鋳造にも対応可能な連続鋳造用鋳型を提供できる。
特に、請求項２記載の連続鋳造用鋳型においては、拡幅部の上側に、更に拡幅部の内幅と同一又はより広い拡大拡幅部を設けるので、鋳型本体の冷却面の全てを、鋳型本体の熱変形を考慮した形状に加工する必要がなくなり、鋳型本体の製作時における作業性が良好となる。
【００２２】
請求項３記載の連続鋳造用鋳型においては、メニスカス部の上側に、更に拡幅部の内幅と同一又はより広い拡大拡幅部を設けるので、例えば溶鋼と接触しない部分の冷却面の形状を単純にでき、鋳型本体の加工を容易にできる。
請求項４記載の連続鋳造用鋳型においては、膨張代を予測計算値を用いて求めるので、拡幅部の形状を容易に把握できる。従って、連続鋳造用鋳型の制作時においては、鋳型本体の熱変形を考慮した鋳型本体の拡幅部の加工を容易にできるので、作業性が良好である。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る連続鋳造用鋳型の説明図である。
【図２】同連続鋳造用鋳型の拡幅部の形状を求めるための予測計算値を示すグラフである。
【図３】同予測計算値を加工した説明図である。
【図４】（Ａ）、（Ｂ）はそれぞれ変形例に係る鋳型本体の説明図である。
【図５】従来例に係る連続鋳造用鋳型の平面図である。
【図６】同連続鋳造用鋳型の鋳型本体の制作時及び熱間時の形状の説明図である。
【図７】同連続鋳造用鋳型の鋳型本体を構成する長辺銅板の温度分布の説明図である。
【符号の説明】
１０：連続鋳造用鋳型、１１：鋳型空間、１２：溶鋼、１３：メニスカス部、１４：鋳型本体、１５：拡幅部、１６：長辺銅板、１７：内側対向面、２０：鋳型本体、２１：長辺銅板、２２：拡幅部、２３：拡大拡幅部、２４：上端、２５：下端、２６：拡大拡幅部、３０：鋳型本体、３１：長辺銅板、３２：メニスカス部、３３：拡幅部、３４：拡大拡幅部、３５：上端、３６：下端、３７：拡大拡幅部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a continuous casting mold in consideration of thermal deformation of a mold during casting.
[0002]
[Prior art]
Conventionally, a continuous casting mold (hereinafter, also simply referred to as a mold) 70 used in a continuous casting facility includes a pair of narrow cooling members 71 and 72 as shown in FIG. Long side members 73 and 74 which are a pair of wide cooling members disposed so as to sandwich the members 71 and 72, bolts 75 are attached to both ends of the long side members 73 and 74 facing each other, and springs (illustrated) No) is fixed by the nut 76.
The short side members 71 and 72 are mirror-symmetrical and have the same configuration, and are fixed to the short side copper plate 77 provided with a number of water guide grooves in the vertical direction on the back side and bolts on the back side of the short side copper plate 77. And a back plate 78 (also referred to as a cooling box). And the short side copper plate 77 is cooled by flowing the industrial water which is an example of a cooling water to a water guide groove through the drainage part and water supply part which were each provided in the upper end part and lower end part of the backplate 78. . On the other hand, the long side members 73 and 74 have substantially the same configuration, but the width of the long side copper plate 79 of the long side members 73 and 74 is longer than the width of the short side copper plate 77 of the short side members 71 and 72. The width of the back plate 80 fixed to the back side of the long side copper plate 79 is longer than the width of the long side copper plate 79.
The mold body 81 is constituted by the short side copper plate 77 of the short side members 71 and 72 and the long side copper plate 79 of the long side members 73 and 74. Further, the inner shape (cooling surface side) of the mold body 81 is a shape corresponding to the volume shrinkage of the cast slab to be manufactured, and the distance between the inner facing surface 82 of the long side copper plate 79 is as shown in FIG. As shown by the dotted line, the mold body 81 is narrowed from the upper end to the lower end.
[0003]
During the continuous casting operation, molten steel is poured from above the mold 70 (above the short side members 71 and 72 and the long side members 73 and 74), and initial casting of the slab as a product is performed by the mold 70, The solidified slab is continuously drawn from the lower part of the mold 70 at a constant speed. At this time, since the mold 70 is vibrated about 150 times / min in the vertical direction with respect to the slab, for example, in the range of 10 mm (also referred to as mold oscillation), the mold 70 moves relative to the slab. The mold 70 is lowered or raised from the slab. Thereby, when the mold 70 is lowered with respect to the slab, a cooling surface (a contact surface with the slab) constituted by the inner facing surface 83 of the short side copper plate 77 and the inner facing surface 82 of the long side copper plate 79, When a gap is generated between the slab and the solidified shell (solidified shell), and when it rises, the mold 70 is pressed against the slab.
Although the molten steel temperature poured into the mold 70 and the surface temperature of the slab at the outlet of the mold 70 differ depending on the operating conditions, the molten steel temperature is usually about 1500 ° C., and the surface temperature of the slab at the outlet of the mold 70 is 800 ˜1200 ° C. The inside of the slab here is in an unsolidified state, that is, in a liquid state.
[0004]
[Problems to be solved by the invention]
However, the above-described continuous casting mold 70 has the following problems.
The cooling surface of the mold body 81 is cooled to about 200 to 300 ° C., for example, but as shown in FIG. 7, a temperature distribution is generated from the upper end portion to the lower end portion of the mold body 81, The temperature is higher than the temperature of other parts. Therefore, as shown by the solid line in FIG. 6, the mold main body 81 is thermally expanded (thermally deformed) by the heat of the molten steel and the cast slab, and in particular, the inner upper part of the mold main body 81 is located on the cooling surface of the central part and the lower part. The main body 81 protrudes greatly inside and deforms.
As described above, the protrusion is generated at the upper part on the inner side of the mold body 81, so that the cooling surface of the mold body 81 and the surface of the slab are not substantially parallel. For this reason, as described above, when the mold 70 is moved relative to the slab, the protruding portion presses and deforms the solidified shell formed on the surface layer portion of the slab, so that the quality of the slab to be manufactured is deteriorated. There is a problem to make. In addition, when the protruding portion presses the solidified shell, the solidified shell may be broken and repaired by cooling the mold 70 again, but at this time, a lap scratch or the like is generated on the surface of the slab, which deteriorates the product quality. There is also a problem. Further, there is a possibility that a slab breakout or the like resulting from this will be caused.
Furthermore, in recent years, the casting speed has been increased in order to improve the efficiency of the continuous casting operation. In particular, the slab is about 1/3 to 1/2 of the slab thickness employed in many continuous casting facilities. With the advent of continuous casting machines equipped with thick molds, it has become possible to see casting speeds that are twice or three times higher than conventional casting machines. As the casting speed increases in this way, the amount of heat extracted into the mold body increases proportionally, and thermal deformation in the mold body has become more prominent.
The present invention has been made in view of such circumstances, and a continuous casting mold capable of producing a slab of good quality by making the shape of the cooling surface of the mold main body a predetermined shape when hot. The purpose is to provide.
[0005]
[Means for Solving the Problems]
The continuous casting mold according to the present invention that meets the above object is a continuous casting mold for producing a slab by cooling and solidifying molten steel put in an enclosed mold space, and is located below the meniscus portion, A widened portion that substantially matches the expansion allowance of the mold body is provided at the time of manufacture on the inner part of the mold body that is in contact with the upper part of the molten steel. Thus, since the widened portion is provided in the inner part of the mold body during production, even if the mold body expands due to heat during hot, the cooling surface of the inner part of the mold body has a predetermined shape, for example, a substantially flat surface. It can be in a state (one step taper).
Here, in the continuous casting mold according to the present invention, it is preferable to provide an enlarged widened portion that is the same as or wider than the inner width of the widened portion on the upper side of the widened portion at the time of manufacture. Thus, since an enlarged widened portion that is the same as or wider than the inner width of the widened portion is provided above the widened portion, it is necessary to process all of the cooling surface of the mold body into a shape that takes into account the thermal deformation of the mold body. Disappears.
[0006]
In the continuous casting mold according to the present invention, it is preferable to provide an enlarged widened portion that is the same as or wider than the inner width of the widened portion on the upper side of the meniscus portion at the time of manufacture. As described above, since the enlarged widened portion that is the same as or wider than the inner width of the widened portion is further provided on the upper side of the meniscus portion, the shape of the cooling surface of the portion that does not contact the molten steel, for example, can be simplified.
In the continuous casting mold according to the present invention, the expansion allowance is preferably obtained using a predicted calculation value. In this way, since the expansion allowance of the mold body during the hot state is obtained, the shape of the widened portion can be easily grasped.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
FIG. 1 is an explanatory diagram of a continuous casting mold according to an embodiment of the present invention, FIG. 2 is a graph showing predicted calculation values for obtaining the shape of the widened portion of the continuous casting mold, and FIG. FIG. 4A and FIG. 4B are explanatory diagrams of the mold main body according to the modified example.
[0008]
As shown in FIG. 1, a continuous casting mold 10 according to an embodiment of the present invention shows a shape for performing numerical analysis, and a molten steel 12 put into an enclosed mold space 11 is shown. It cools and solidifies and manufactures a slab (not shown). The continuous casting mold 10 is provided with a widened portion 15 which is located below the meniscus portion 13 and which is substantially coincident with the expansion allowance of the mold body 14 at the time of manufacture, at the inner portion of the mold body 14 where the upper part of the molten steel 12 contacts. It has been. Note that the widened portion 15 means a widened portion of the mold space 11 formed by the mold body 14. For the mold body 14, for example, 0. It is a hollow shape having a depth of about 1 to 0.5 mm. This will be described in detail below.
[0009]
As described above, the continuous casting mold 10 is manufactured by combining a short side member that is a pair of narrow cooling members and a long side member that is a pair of wide cooling members (FIG. 5). reference). Further, the long side member of the continuous casting mold 10 is made of copper which is an example of a metal having good thermal conductivity, and the long side copper plate 16 having a water flow portion provided on the back side, and the back side of the long side copper plate 16. A back plate (also referred to as a cooling box or a water box) that is an example of a support member fixed by a bolt that is an example of an attachment means is provided on the side, and water is passed through a water supply part and a drain part provided on the back plate. The long side copper plate 16 is cooled by flowing industrial water, which is an example of cooling water, to the part. Note that the short side member of the continuous casting mold 10 has substantially the same configuration as the long side member described above, and the mold main body 14 is configured by the long side copper plate 16 of the long side member and the short side copper plate of the short side member. ing. As a result, the mold space 11 is formed at the center of the mold body 14 in plan view.
[0010]
The vertical length L from the upper end to the lower end of the long side copper plate 16 and the short side copper plate constituting the mold body 14 is, for example, about 700 to 1000 mm, and the thickness thereof is, for example, about 10 to 50 mm. Moreover, since the width | variety of the long side copper plate 16 (the width of a short side copper plate is also the same) is short from an upper end part to a lower end part, the inner side opposing surface 17 of the long side copper plate 16 of a pair of long side members, and The inner peripheral length formed by the inner facing surfaces of the short-side copper plates of the pair of short-side members is shorter at the lower end than at the upper end of the mold body 14. This is determined in consideration of the volume shrinkage of the slab such as solidification shrinkage and solid shrinkage, for example, and the numerical value is determined based on past performance data, the linear expansion amount and temperature of the slab. It is preferable.
[0011]
On the upper part of the long side copper plate 16 of the mold body 14, a widened portion 15 having a groove shape in the width direction of the long side copper plate 16 is provided. The widened portion 15 gradually widens from the lower side to the central portion of the upper side (upper region) of the long side copper plate 16 and gradually decreases from the central portion to the upper side. The same applies to the short side copper plate.
Here, how to obtain the shape of the widened portion 15 provided inside the mold body 14 will be described using the long-side copper plate 16.
First, when the inner side of the long side copper plate of the mold body at the time of production is assumed to be flat (also referred to as a one-step taper) (reference taper), the inner side of the long side copper plate is hot (when molten steel 12 is being charged). The shape is thermally deformed, for example, from the state of the two-dot chain line in FIG. 6 to the state of the solid line (shows expansion allowance). In addition, the predicted calculation value of the inner shape of the long side copper plate at this time is, for example, a conventionally known finite element method (FEM) using a drawing speed of a slab, a thickness of a mold body (long side copper plate), a cooling rate, and the like. Can be obtained. The result of this prediction calculation is shown in FIG. In addition, the position where the distance from the upper edge of the long side copper plate is 100 mm corresponds to the position of the molten steel surface (liquid surface).
As can be seen from the fact that the distance from the upper edge of the long side copper plate and the amount of displacement at each position in the height direction show a proportional relationship, this reference taper is applied from the upper end to the lower end of the long side copper plate and the volume shrinkage of the slab. In consideration of the continuous slope. However, the shape of the copper plate on the long side (copper plate surface profile) during the hot state has greatly increased the amount of displacement in the vicinity of the molten steel surface, so it can be predicted that significant thermal deformation will occur in the vicinity of the molten metal surface. .
[0012]
Moreover, the result of having calculated | required the inclination in each part of the height direction of a long side copper plate based on the data of FIG. 2 is shown in FIG. The inclination is the ratio of the change to the distance between the long side copper plates in each section when the long side copper plate is divided every 10 mm in the height direction, converted into a value per 1 m, and is shown by the following formula. It is.
Inclination [% / m] = (W1-W2) / W3 × 100 × (1000/10)
Here, W1 is the distance between the long side copper plates facing each other at the upper end position of each portion, W2 is the distance between the long side copper plates facing each other at the lower end position of each portion, and W3 is facing at the lower end position of the long side copper plate. This means the distance between the long side copper plates (see FIG. 6).
[0013]
Since the reference taper is continuously inclined in consideration of the volume shrinkage of the slab from the upper end to the lower end of the long side copper plate, as shown in FIG. The inclination of each part is a substantially constant value (about 0.4% / m). However, since the long-side copper plate (copper plate surface profile) during hot time has greatly increased or decreased the inclination in the vicinity of the molten steel surface (liquid surface), it can be predicted that significant thermal deformation will occur in the vicinity of the molten metal surface. . In addition, in the position where the distance from a long side copper plate upper end is 450 mm, the inclination becomes a numerical value substantially near a reference | standard taper. Therefore, at the position where the distance from the upper end of the long side copper plate is 450 mm or more, it is preferable to mainly consider the influence of the volume shrinkage of the slab without considering the thermal deformation of the long side copper plate.
[0014]
As described above, the widened portion 15 is provided on the inner upper portion of the mold main body 14 that is most susceptible to the thermal influence of the molten steel 12, and the central portion and the lower portion are formed in a conventional shape, thereby taking into account the thermal deformation of the mold. The casting mold 10 can be manufactured.
Therefore, the shape of the widened portion 15 is, for example, from the surface of the reference taper to the mold body 14 side by a depth corresponding to the difference between the value of the copper plate surface profile and the value of the reference taper at each distance from the upper end of the long side copper plate. The widened portion 15 can be provided inside the long side copper plate 16 by cutting. That is, in FIG. 2, the line of the copper plate surface profile that is symmetrical with respect to the solid line of the reference taper is the shape of the widened portion 15 to be obtained (solid line in FIG. 1).
Based on this data, the long side copper plate 16 provided with the widened portion 15 is manufactured by processing the long side copper plate using an NC machine tool. In addition, this process can also be performed with respect to the long side copper plate 16 continuously or intermittently at predetermined intervals (for example, about 1 to 10 mm).
[0015]
Thereby, when the continuous casting operation is hot, the continuous casting mold 10 is expanded by the heat of the molten steel 12, so that the shape of the long side copper plate 16 is thermally deformed from the solid line in FIG. 1 to the two-dot chain line. . Accordingly, during the hot state, the widened portion 15 of the long side copper plate 16 expands by the expansion allowance due to the thermal effect of the molten steel 12, so that the inner shape of the mold body 14 is substantially the predetermined shape (1 Step taper). Thereby, the cooling surface of the mold main body 14 and the surface of the slab can be made substantially parallel.
In addition, in each distance from the upper end of the long side copper plate 16, when providing the widened portion 15 having a depth corresponding to the difference between the numerical value of the copper plate surface profile and the numerical value of the reference taper, the portion of the long side copper plate 16 where the widened portion 15 is provided. The thickness changes. Thereby, the expansion allowance of the mold body 14 also changes. Therefore, the long side copper plate 16 is provided with the widened portion 15 corresponding to thermal deformation by predicting and calculating using the finite element method in consideration of this thickness and determining the inner shape of the long side copper plate 16. Can do.
[0016]
Next, a modified example of the continuous casting mold 10 will be described using the long side copper plate of the mold body. The same applies to the short side copper plate, and the size and material of the mold main body are the same as those of the continuous casting mold described above. Since it is the same as 10, detailed description is omitted.
As shown in FIG. 4A, the mold body 20 is provided with an enlarged widened portion 23 that is the same as the inner width of the widened portion 22 on the upper side of the widened portion 22 provided on the upper part of the long side copper plate 21 at the time of manufacture. It is a thing. Therefore, from the position X where the inner width of the widened portion 22 provided on the long side copper plate 21 is the widest to the upper end 24 of the long side copper plate 21, the same inner width is obtained. The widened portion 22 is substantially the same as the widened portion 15 except that the shape on the upper side of the widened portion 15 is different.
[0017]
Moreover, the shape of the long side copper plate 21 from the position X to the lower end 25 of the long side copper plate 21 is the same shape as the continuous casting mold 10. Accordingly, it is possible to reliably prevent the portion of the long side copper plate 21 that is most susceptible to heat from protruding near the molten metal surface, and to prevent all the cooling surfaces of the long side copper plate 21 from being moved to the long side copper plate 21. It is not necessary to process into a shape that takes into account the thermal deformation of 21.
It is also possible to provide an enlarged widened portion 26 that gradually becomes wider than the inner width of the widened portion 22 on the upper side of the widened portion 22 toward the upper end 24 of the long side copper plate 21 (in FIG. 4A). Two-dot chain line). Thereby, the process of the wide part 22 with respect to the long side copper plate 21 becomes easy, and workability | operativity becomes still more favorable.
[0018]
As shown in FIG. 4 (B), the mold body 30 is provided with an enlarged widened portion 34 that is the same as the inner width of the molten metal surface position Y of the widened portion 33 on the upper side of the meniscus portion 32 of the long side copper plate 31 at the time of manufacture. It is provided. Therefore, the inner width is the same from the surface Y of the long side copper plate 31 to the upper end 35 of the long side copper plate 31. The widened portion 33 is substantially the same as the widened portion 15 except that the shape on the upper side of the widened portion 15 is different.
Moreover, the shape of the long side copper plate 31 from the molten metal surface position Y to the lower end 36 of the long side copper plate 31 is the same shape as the continuous casting mold 10. Thereby, since the shape of the cooling surface of the part which does not contact molten steel can be simplified, the process of the long side copper plate 31 can be made easy.
In addition, it is also possible to provide the enlarged widening part 37 which becomes gradually wider than the inner width of the molten metal surface position Y toward the upper end 35 of the long side copper plate 31 on the upper side of the meniscus part 32 (FIG. 4B). Middle two-dot chain line).
[0019]
As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, the present invention is also applied to the case where the continuous casting mold of the present invention is configured by combining some or all of the above-described embodiments and modifications.
In the above embodiment, the case of using a continuous casting mold having a mold body having a rectangular opening in a plan view is described. However, the shape of the opening in a plan view is manufactured. Of course, it is possible to adopt a polygonal shape (for example, a convex shape, a concave shape, a hexagonal shape, an octagonal shape, etc.), a circular shape, an elliptical shape or the like in accordance with the cross-sectional shape of the slab.
[0020]
And in the said embodiment, the case where the assembly mold which combined a pair of long side member and a pair of short side member was used as a casting mold for continuous casting was demonstrated. However, the present invention is also applicable to, for example, a tubular mold in which a copper tube is accommodated in a housing having a water guide groove, a block mold in which a water guide groove is drilled in a cast or forged copper block, and the like. In addition, by changing the type of a mold used as a continuous casting mold in this way, for example, a slab (for example, a width of about 1000 to 2500 mm, a thickness of about 200 to 300 mm), a bloom (for example, a width and a thickness of about It is possible to manufacture slabs such as billets (for example, about 100 to 200 mm in width and thickness), beam blanks (used for H-shaped steel), and the like.
Furthermore, in the above embodiment, the case where the shape of the cooling surface inside the mold body is a one-step taper has been described, but other shapes may be used, for example, a conventionally known two-step taper, multi-taper, or the like. Is also possible.
[0021]
【The invention's effect】
In the continuous casting mold according to any one of claims 1 to 4, since the widened portion is provided in the inner portion of the mold body at the time of production, the cooling surface of the inner portion of the mold body is expanded even when the mold body is expanded by heat during the hot process. Can be in a predetermined shape, eg, substantially planar. Thereby, since generation | occurrence | production of the protrusion part to the molten steel side which arises in a part of cooling surface with the heat | fever of molten steel can be prevented, the contact with the conventional protrusion part and the solidification shell of a slab can be prevented. Therefore, it is possible to improve the surface condition of the slab to be manufactured, improve the product quality, and reduce the possibility of occurrence of breakout of the slab. In addition, even when the casting speed is increased, by obtaining the shape when the mold body is thermally deformed in advance, a widened portion can be provided according to the expansion allowance of the mold body. A continuous casting mold can be provided.
In particular, in the continuous casting mold according to claim 2, since an enlarged widened portion that is the same as or wider than the inner width of the widened portion is further provided on the upper side of the widened portion, all of the cooling surface of the mold main body is attached to the mold body. There is no need to process into a shape that takes heat deformation into consideration, and the workability at the time of manufacturing the mold body is improved.
[0022]
In the continuous casting mold according to claim 3, since an enlarged widened portion that is the same as or wider than the inner width of the widened portion is further provided on the upper side of the meniscus portion, for example, the shape of the cooling surface of the portion that does not contact the molten steel is simply And the mold body can be easily processed.
In the continuous casting mold according to the fourth aspect, since the expansion allowance is obtained using the predicted calculation value, the shape of the widened portion can be easily grasped. Therefore, at the time of production of the continuous casting mold, the work of the widened portion of the mold main body considering the thermal deformation of the mold main body can be easily performed, so that the workability is good.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a continuous casting mold according to an embodiment of the present invention.
FIG. 2 is a graph showing predicted calculation values for obtaining the shape of the widened portion of the continuous casting mold.
FIG. 3 is an explanatory diagram obtained by processing the predicted calculation value.
4A and 4B are explanatory views of a mold body according to a modification.
FIG. 5 is a plan view of a continuous casting mold according to a conventional example.
FIG. 6 is an explanatory view of the shape during production and hot production of the mold body of the continuous casting mold.
FIG. 7 is an explanatory view of a temperature distribution of a long-side copper plate constituting a mold body of the continuous casting mold.
[Explanation of symbols]
10: mold for continuous casting, 11: mold space, 12: molten steel, 13: meniscus part, 14: mold body, 15: widened part, 16: long side copper plate, 17: inner facing surface, 20: mold body, 21: Long side copper plate, 22: widened portion, 23: enlarged widened portion, 24: upper end, 25: lower end, 26: enlarged widened portion, 30: mold body, 31: long side copper plate, 32: meniscus portion, 33: widened portion, 34: Enlarged wide part, 35: Upper end, 36: Lower end, 37: Enlarged widened part

Claims

囲まれた鋳型空間に投入された溶鋼を冷却して凝固させ鋳片を製造する連続鋳造用鋳型において、
メニスカス部より下位置にあって、溶鋼上部が接する鋳型本体の内側部分に、製作時に、前記鋳型本体の膨張代に実質的に一致する拡幅部が設けられていることを特徴とする連続鋳造用鋳型。In a continuous casting mold for producing a slab by cooling and solidifying molten steel put in an enclosed mold space,
For continuous casting, characterized in that, at the time of manufacture, a widened portion that is substantially below the expansion allowance of the mold body is provided on the inner part of the mold body that is located below the meniscus portion and that is in contact with the molten steel upper portion. template.

請求項１記載の連続鋳造用鋳型において、製作時に、前記拡幅部の上側に、更に前記拡幅部の内幅と同一又はより広い拡大拡幅部を設けたことを特徴とする連続鋳造用鋳型。2. The continuous casting mold according to claim 1, further comprising an enlarged widened portion that is the same as or wider than the inner width of the widened portion above the widened portion at the time of manufacture.

請求項１記載の連続鋳造用鋳型において、製作時に、前記メニスカス部の上側に、更に前記拡幅部の内幅と同一又はより広い拡大拡幅部を設けたことを特徴とする連続鋳造用鋳型。2. The continuous casting mold according to claim 1, further comprising an enlarged widened portion that is the same as or wider than the inner width of the widened portion above the meniscus portion at the time of manufacture.

請求項１〜３のいずれか１項に記載の連続鋳造用鋳型において、前記膨張代は予測計算値を用いて求めたことを特徴とする連続鋳造用鋳型。The continuous casting mold according to any one of claims 1 to 3, wherein the expansion allowance is obtained by using a predicted calculation value.