JP3815425B2 - Cold rolling method - Google Patents

Description

【００６１】
ただし、ｆｓ（％）：先進率、Ｖｓ（ｍ／ｍｉｎ）：板速度、Ｄ（ｍ）：ワークロール直径、ｎ（ｒｐｍ）：ロール回転速度（２）目標先進率との偏差を式（３）より計算する。
【００６２】
【数２】

【００６３】
ただし、Δｆｓ（％）：目標先進率との偏差、ｆｓ（％）：圧延中の先進率、ｆｓ^※（％）：目標先進率
目標先進率は、図１７に示すような、チャタリングの発生しない安定な先進率範囲の調査を元にして決定する。
【００６４】
（３）式（４）より第２の圧延油供給系統のエマルション供給量の変更量ΔＱを計算する。
【００６５】
【数３】

【００６６】
ただし、ΔＱ（Ｌ／ｍｉｎ）はエマルション供給量の変更量、Δｆｓ（％）は圧延中の先進率と目標先進率との偏差、∂ｆｓ／∂μ（％／−）は、先進率ｆｓに対する摩擦係数μの影響係数、∂μ／∂Ｑ（−／Ｌ／ｍｉｎ）は、摩擦係数μに対するエマルション供給量Ｑの影響係数、である。
【００６７】
∂ｆｓ／∂μは、例えば、Ｂｌａｎｄ＆Ｆｏｒｄの先進率式の摩擦係数μに関する導関数式（５）で与える。
【００６８】
【数４】

【００６９】
【数５】

【００７０】
ただし、μは圧延中の摩擦係数、ｋｍ（ｋｇ／ｍｍ² ）は圧延材の平均変形抵抗、Ｈ（ｍｍ）、ｈ（ｍｍ）は入・出側板厚、σｂ（ｋｇ／ｍｍ² ）、σｆ（ｋｇ／ｍｍ² ）は圧延中の前・後方ユニット張力、Ｒ′（ｍｍ）はロール偏平半径を表す。
【００７１】
なお、圧延中の平均変形抵抗ｋｍおよび摩擦係数μは、Ｈｉｌｌの圧延荷重式（７）およびＢｌａｎｄ＆Ｆｏｒｄの先進率式（８）に圧延中の測定荷重Ｐ、ｆｓを代入し、両式を連立させて求める。
【００７２】
【数６】

【００７３】
【数７】

【００７４】
ただし、Ｗ（ｍｍ）は板幅、Ｐ（ｔｏｎ）は圧延中の圧延荷重、ｆｓ（％）は圧延中の先進率、を表す。
【００７５】
また、∂μ／∂Ｑは、圧延実験および操業上採取されるデータをもとに決定する。以下に、その一例を示す。
【００７６】
エマルション供給量とプレーアウト油膜厚ＰΦの関係は、プレートアウト試験による調査の結果、式（９）で表される。
【００７７】
【数８】

【００７８】
ただし、ＰΦはプレートアウト油膜厚（μｍ）、ｃはエマルション濃度（％）、ｆはエマルション付着効率（％）、Ｑはエマルション供給量（Ｌ／ｍｉｎ）、Ｗはスプレー幅（ｍ）、Ｖｓはスプレー部の鋼板速度（ｍ／ｍｉｎ）を表す。
【００７９】
また、摩擦係数μは、プレートアウト油膜厚ＰΦとワークロールの表面粗さΛの比の関数として式（１０）で表される。
【００８０】
【数９】

ただし、ｎ、ｍは定数、Λはワークロールの表面粗さ（μｍ）である。
【００８１】
式（９）を式（１０）に代入し、エマルション供給量Ｑの導関数を計算すると、式（１１）が得られる。
【００８２】
【数１０】

【００８３】
ただし、Ｑ（Ｌ／ｍｉｎ）はエマルション供給量、ｃ（％）はエマルション濃度、ｆ（％）はエマルション付着効率、ｗ（ｍ）はスプレー幅、Ｖｓ（ｍ／ｍｉｎ）はスプレー部の鋼板速度、Λ（μｍ）はワークロールの表面粗さ、ａ，ｍ，ｎは定数。
【００８４】
（４）ΔＱに応じて流量制御弁３０の弁開度を変更し流量制御を行う。
【００８５】
一方、循環式圧延油供給系統のエマルションは、タンク１７よりポンプ１９、配管２０を経由し、潤滑油としてヘッダー４ａ，４ａよりロールバイト入側へ供給される。また、冷却としてヘッダー４ｂ，４ｂよりスタンド出側ロールへ供給される。その後、オイルパン１５により回収され、配管１６を経由してタンク１７へ戻る。
【００８６】
【実施例】
（実施例１）図３は、全５スタンドの冷間タンデム圧延機の第４，５スタンドに本発明を適用した実施形態１（図１）の、特に＃４、＃５スタンドの潤滑用クーラントヘッダーの配置に関して詳細に示したものである。このようなヘッダー配置の５スタンド・タンデムミルを用い、母材厚１．８ｍｍ、板幅９００ｍｍの硬質ブリキ原板を仕上げ厚０．１８３ｍｍまで冷間圧延を行なった際の、使用ヘッダー、エマルション濃度およびエマルション供給量の組み合わせを表１に示す。なお、圧延油として牛脂系エマルション（４０℃で基油粘度４０ｃＳｔ、エマルション温度６０℃）を用いた。図３中、１は本発明による潤滑用クーラントヘッダー（ヘッダーＢ）を示し、２は従来の潤滑用クーラントヘッダー（ヘッダーＡ）を示し、３は従来技術（特公昭59-24858号）の別系統の潤滑用クーラントヘッダーを示す。
【００８７】
【表１】

【００８８】
以上の条件で圧延速度を変更しつつ圧延を行い、鋼板付着油量および第５スタンドの摩擦係数を調査した。図１２に圧延速度と鋼板付着油量の関係を、そして、図１３に圧延速度と第５スタンドの摩擦係数の関係を、本発明と従来方式１および従来方式２を比較して示した。なお、鋼板付着油量は、鋼板表面の油分をヘキサン等の有機溶剤にて抽出し、抽出油分量を測定する方法（溶剤抽出法）により行なった。
【００８９】
従来方式１では、８００ｍｐｍ以上の速度域で鋼板付着量が表裏面とも減少した。また、従来方式２では、１０００ｍｐｍでは、従来方式１よりも裏面のみ鋼板付着量が増加しているものの、１２００ｍｐｍ以上の高速域では付着油量が急激に低下した。これに対応して、従来方式１、従来方式２の場合の摩擦係数は、高速圧延域で上昇し、それぞれ速度１２００ｍｐｍ、１５００ｍｐｍにおいて潤滑不足により発生するチャタリングが発生した。
【００９０】
一方、本発明では、表裏面とも１２００ｍｐｍ以上の高速域でも安定した鋼板付着油量が得られた。その結果、第５スタンドの摩擦係数の上昇が抑制され、高速域まで安定した摩擦条件が得られている。特に、高速域での摩擦係数の上昇がほとんど生じることがなくなり、潤滑不足により発生するチャタリングが発生しなくなった。
【００９１】
（実施例２）実施例１と同じ５スタンド・タンデムミルを用い、母材厚２．３ｍｍ、板幅９００ｍｍの軟質ブリキ原板を仕上げ厚０．１８３ｍｍまで冷間圧延を行なった。エマルション性状および供給量は、表１と同じである。なお、本実施例の対象圧延材は、実施例１の対象圧延材よりも軟質であるが冷圧率が高く、従来の循環式圧延油供給系統により圧延すると、特に圧延速度の高い第５スタンドにおいてヒートスクラッチ疵の発生頻度が高かった。
【００９２】
以上の条件で圧延速度を変更しつつ圧延を行い、鋼板付着油量および第５スタンドの摩擦係数を調査した。図１４に圧延速度と第５スタンドの摩擦係数の関係を、図１５に、圧延速度と第５スタンド出側の鋼板温度の関係をヒートスクラッチ疵の発生状況も含めて示す。いずれも、本発明と従来方式１および従来方式２を比較して示した。従来方式１、従来方式２の摩擦係数は、高速圧延域で上昇した。第５スタンド出側の鋼板温度は、従来方式１、従来方式２の場合、速度とともに温度上昇が大きく、従来方式１では１５００ｍｐｍ、従来方式２では１７００ｍｐｍ以上で１７０℃を越え、ヒートスクラッチ疵が発生した。
【００９３】
これに対し、本発明の場合、第５スタンドの摩擦係数の上昇が抑制され、高速域まで安定した摩擦条件が得られている。特に、高速域での摩擦係数の上昇がほとんど生じなくなった。このように本発明によると高速圧延域での摩擦係数の上昇を抑制できるため、摩擦発熱が低減し、結果として鋼板温度が低下するため、ヒートスクラッチ疵が発生しなくなった。
【００９４】
（実施例３）全５スタンドのタンデム圧延機のＮｏ．４、５スタンドに本第２発明を適用した実施形態２（図２）を用い、実施例１と同じ母材厚１．８ｍｍ、板幅９００ｍｍの硬質ブリキ原板を仕上げ厚０．１８３ｍｍまで冷間圧延を行った。圧延油に牛脂系エマルション（４０℃で基油粘度４０ｃＳｔ、エマルション温度６０℃）を用い、エマルション濃度、平均粒径及び供給量は表２に示すとおりである。これは本第１発明の実施例１と比較して、エマルション濃度は同一、エマルション平均粒径は大きく、そしてエマルション供給量は少ない条件である。
【００９５】
以上の条件で圧延速度を変更しつつ圧延を行い、鋼板付着油量及び第５スタンドの摩擦係数を調査した。図２６に圧延速度と鋼板付着油量の関係を、そして、図２７に圧延速度と第５スタンドの摩擦係数の関係を示す。本第３発明によると、本第１発明による実施例１と同様に、表裏面とも１２００ｍｐｍ以上の高速域でも安定した鋼板付着油量が得られた。その結果、第５スタンドの摩擦係数の上昇が抑制され、高速域まで安定した摩擦条件が得られている。特に、高速域での摩擦係数の上昇がほとんど生じることがなくなり、潤滑不足により発生するチャタリングが発生しなくなった。
【００９６】
【表２】

【００９７】
（実施例４）本発明の効果を確認するために行った試験結果と、従来の循環式圧延油供給系統を用いた場合の比較を図２４に示す。なお圧延条件およびエマルション条件は以下の通り。
【００９８】
〈圧延条件〉・圧延材鋼種〜ブリキ材サイズ〜母材厚１．８ｍｍ、仕上厚０．１８３ｍｍ、板幅９００ｍｍ・ワークロール：Φ６００ｍｍ・Ｎｏ．５スタンド圧下率３０％
【表３】

【００９９】
図２４（ａ）は圧延中のＮｏ．５スタンドの先進率と圧延速度の関係、図２４（ｂ）は本発明によるエマルション供給量と圧延速度の関係、図２４（ｃ）は従来技術によるエマルション供給量と圧延速度の関係を示す。本発明を用いた場合のエマルション供給量は、１０００ｍｐｍまでが９０Ｌ／ｍｉｎと低く、１０００ｍｐｍ以降は速度とともに増加している。このような供給量制御を行うことにより、圧延中の先進率は目標先進率（１０００ｍｐｍ以上において、０．３〜０．４％）に制御されるため、安定圧延が可能となり、チャタリング未発生のまま２０００ｍｐｍまで加速できた。一方、従来の循環式圧延油供給系統を用いた場合、１０００ｍｐｍ以降、速度とともに先進率が上昇しはじめた。これに対し、エマルション供給量を２０００Ｌ／ｍｉｎから３４０Ｌ／ｍｉｎまで増加させたが、１５００ｍｐｍにて安定先進率範囲を外れチャタリングが発生した。このため、１５００ｍｐｍ以上の加速は不可能であった。
【０１００】
以上の結果より、本発明を用いることにより、高速域において、安定な先進率範囲に制御でき、適正な潤滑状態を確認できるためチャタリングを防止できることがわかる。
【０１０１】
本発明を用い、仕上厚０．２１ｍｍ以下の硬質薄物ブリキ材を圧延した場合の圧延速度の分布を、従来の循環式圧延油供給系統の場合と比較して図２５に示す。本発明を用いることにより、高速域で発生するチャタリングの発生頻度が低減するため、平均圧延速度が１５００ｍｐｍから１９００ｍｐｍに向上できた。
【０１０２】
【発明の効果】
以上説明したように本第１発明および本第２発明によれば、循環式圧延油供給系統を用いた鋼板の冷間圧延方法において、１０％以上の高濃度なエマルションの直接供給方式を用いることなく、高速圧延域での鋼板付着油量を大輻に向上できる。これにより、高速圧延時に発生していた潤滑不足が解消され、ヒートスクラッチの発生を防止でき、圧延速度が向上するため、生産性が大幅に向上する。また、ロールの損傷を防止できるため、ロール寿命の向上によるロール原単位の向上等の付帯効果も期待できる。
【０１０３】
本第３発明によれば、第２の圧延油供給系統から平均粒径の大きいエマルションを、プレートアウトのための転相時間を最大限に確保できる鋼板位置に供給し、その供給量を調整することにより、高速圧延域においても先進率を広範囲に制御可能となり、チャタリングの発生しない目標先進率への制御が可能となる。その結果、チャタリングの発生を未然に防止できるため、高速圧延が可能となり生産性が大幅に向上する。
【図面の簡単な説明】
【図１】本発明の第１実施形態に係わるタンデム圧延機への適用例を示す図。
【図２】本発明の第２実施形態に係わるタンデム圧延機への適用例を示す図。
【図３】Ｎｏ．４，５スタンドの潤滑用クーラントヘッダーの配置図。
【図４】試験時のヘッダー取付位置を示す図。
【図５】鋼板付着油量の測定結果を示す図。
【図６】プレートアウト層の生成過程の模式図。
【図７】プレートアウト試験方法を示す図。
【図８】転相時間と付着効率の関係図。
【図９】鋼板付着油量と圧延速度の関係図。
【図１０】エマルション平均粒径と付着効率の関係図。
【図１１】エマルション供給量と鋼板付着油量の関係図。
【図１２】本発明と従来方式の鋼板付着油量の比較を示す図。
【図１３】本発明と従来方式の摩擦係数の比較を示す図。
【図１４】本発明と従来方式の第５スタンドの摩擦係数の比較を示す図。
【図１５】本発明と従来方式の第５スタンド出側の鋼板温度の比較を示す図。
【図１６】請求項３の発明方法の適用例を示す図。
【図１７】チャタリング発生と先進率の関係を示す図。
【図１８】試験時のヘッダー取付位置を示す図。
【図１９】エマルション供給量と先進率の関係を示す図。
【図２０】エマルション供給量と鋼板付着油量の関係を示す図。
【図２１】エマルション供給量と先進率の関係を示す図。
【図２２】エマルション供給量と鋼板付着油量の関係を示す図。
【図２３】エマルション平均粒径と先進率の変更範囲の関係を示す図。
【図２４】請求項３の発明の効果の説明図で、（ａ）破線新率と圧延速度の関係を示し、（ｂ）は本発明による別圧延油強休憩等のエマルション流量を示し、（ｃ）は従来技術のエマルション流量を示す。
【図２５】圧延速度の分布の比較を示す図。
【図２６】圧延速度と鋼板油付着量との関係を示す図で、（a ）は表面、(b) は裏面の鋼板油付着量を示す。
【図２７】圧延速度とＮｏ．５スタンドの摩擦係数の関係を示す図。
【符号の説明】
１．．．ワークロール、
２．．．バックアップロール、
３．．．ストリップ、
４ａ．．．潤滑用クーラントヘッダ、
４ｂ．．．冷却用クーラントヘッダ、
５．．．潤滑用クーラントヘッダ、
６．．．平均粒径の大きいエマルションの貯蔵タンク、
７．．．温水タンク、
８．．．圧延油原油タンク、
９．．．界面活性剤タンク、
１０ａ，１０ｂ，１０ｃ．．．ポンプ、
１１ａ，１１ｂ，１１ｃ．．．バルブ、
１２．．．アジテータ、
１３．．．エマルション供給用ポンプ、
１４．．．圧延油供給ライン、
１５．．．回収オイルパン、
１６．．．戻り配管、
１７．．．循環式の第１の圧延油供給タンク、
１８．．．アジテータ、
１９．．．エマルション供給用ポンプ、
２０．．．圧延油供給ライン、
３０．．．バルブ、
３１．．．制御装置、
３２．．．パルスジェネレータ、
３３．．．スタンド出側の板速度計。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for spraying a coolant for lubrication in a cold rolling mill that uses a circulating rolling oil supply system, and more particularly to a cold rolling method for a steel sheet that prevents chattering during high speed rolling.
[0002]
[Prior art]
In cold rolling, lubricating oil is required to reduce the friction between the steel sheet and the roll during rolling. In addition, the roll and the steel plate must be cooled in order to remove frictional heat generation and processing heat generation. The rolling oil (coolant) supply system in cold rolling includes a direct system (direct system), a circulation system (recirculation system), and a hybrid system that is a compromise.
[0003]
The direct rolling oil supply system (direct system) is excellent in lubricity and cooling properties because high-concentration emulsion rolling oil is sprayed on the steel sheet for the purpose of lubrication and water is sprayed on the roll for the purpose of cooling. However, unlike the circulation system, since the emulsion rolling oil is not circulated, the basic unit of the rolling oil is high.
[0004]
On the other hand, the circulating rolling oil supply method (recirculation method) is a steel plate and roll for the purpose of lubrication and cooling while circulating low-concentration emulsion rolling oil prepared by mixing and stirring rolling oil and cooling water in advance. The basic unit of rolling oil is low. However, it cannot be denied that the lubricity and the cooling performance are inferior compared with the direct rolling oil supply system. Therefore, in the conventional circulation system, especially when a thin material having a finished sheet thickness of 0.2 mm or less is rolled at high speed, lubrication becomes insufficient, and rolling mill vibration called chattering and surface flaws called heat scratch occur, so the rolling speed There was a problem that could not be raised.
[0005]
On the other hand, as a conventional technique for improving the lubricity of the circulating rolling oil supply system, a high-concentration emulsion of 10% or more is provided separately from the circulating rolling oil supply system that supplies an emulsion of less than 10%. A method (Patent Document 1) is proposed in which the steel sheet is directly supplied at a rate of 100 to 200 L / min to the lower surface of the steel plate immediately before the bite bites.
[0006]
However, the above prior art has the following problems.
[0007]
a) Emulsion rolling oil sprayed on the surface of a steel sheet when investigating the property that the oil and water emulsified and dispersed in water separates into oil and water and the oil component adheres to the metal surface, that is, the relationship between the plate-out property and the emulsion concentration. It was found that the ratio of the amount of oil and fat that plate out to the steel sheet surface (hereinafter referred to as adhesion efficiency) to the amount of oil and fat contained in the oil decreases as the emulsion concentration is increased. Therefore, even if the emulsion concentration is increased, a sufficient plate-out layer cannot be obtained. Therefore, when rolling at high speed, the lubrication effect is small and has been a problem.
[0008]
b) During high-speed rolling, heat scratches may occur not only on the lower surface side of the steel sheet but also on the upper surface side. In the high-speed rolling zone, not only the lower surface but also the amount of oil adhering to the steel plate on the upper surface is reduced, and improving the lubricity only on the lower surface of the steel plate is insufficient.
[0009]
c) The use of the direct supply system for emulsions with a concentration of 10% or more is limited to the permissible range of increase in concentration in the circulation system tank. That is, when the oil concentration of the emulsion in the circulation system is, for example, 4%, the replenishment amount of rolling oil lost due to leakage and scum-out is 50 L / On the other hand, in the above prior art (Patent Document 1), the rolling oil supplied directly reaches 600 L / hr to 1200 L / hr in the above-mentioned prior art (Patent Document 1). Will be increased. On the other hand, depending on the rolling material, when lubrication with a high concentration emulsion is performed, the friction coefficient between the roll and the steel sheet decreases, and abnormal rolling such as slip occurs, so the emulsion concentration in the circulation system tank has a certain upper limit value. It is not desirable to exceed it. Therefore, the direct supply method has a problem that it can be used only within the allowable range of the restriction on the increase in concentration.
[0010]
As a conventional technique for preventing chattering, a method of paying attention to an advanced rate as a control index, controlling a coolant supply amount so that the advanced rate becomes an appropriate value, and adjusting to an appropriate lubrication state is proposed. For example, there is a method of calculating the coolant supply amount from the friction coefficient model equation and controlling the supply amount (Patent Document 2).
[0011]
However, with the recent trend of tinplate products, which are hard and thin gauges, higher rolling speeds are being promoted to improve productivity. In the product production process, chattering due to insufficient lubrication also occurs, which is an impediment to high-speed rolling. That is, in the high-speed rolling zone, chattering due to insufficient lubrication and chattering due to excessive lubrication occur. For this reason, in order to prevent chattering, means for controlling the lubricating state over a wide range is required.
[0012]
In contrast, in cold tandem rolling mills using a circulating rolling oil supply system, emulsion oil is generally supplied to the roll tool for both lubrication and cooling, but the advanced rate is used as a control index. Even if the coolant supply amount was changed, the change range of the advanced rate was narrow, and it was difficult to control to the targeted advanced rate. That is, an appropriate lubrication state could not be obtained and chattering could not be prevented.
[0013]
[Patent Document 1]
Japanese Examined Patent Publication No. 59-24888 (claims, etc.)
[0014]
[Patent Document 2]
Japanese Patent Publication No. 6-13126, (Claims, etc.)
[0015]
[Problems to be solved by the present invention]
An object of the present invention is to eliminate lack of lubrication during high-speed rolling in a cold rolling method using a circulating rolling oil supply system without using a direct supply system of an emulsion having a concentration of 10% or more.
[0016]
Another object of the present invention is to eliminate insufficient lubrication during high-speed rolling by using a rolling oil supply system different from the circulating rolling oil supply system.
[0017]
It is another object of the present invention to prevent chattering during high-speed rolling by controlling the advanced rate during rolling within the target advanced rate range.
[0018]
[Means for Solving the Problems]
  The first invention is 1200 using a circulating rolling oil supply system. mpm In the above-described cold rolling method of a steel sheet that performs high-speed rolling, the emulsion is sprayed directly on the upper and lower surfaces of the steel sheet at the position where the following equation is satisfied on the upstream stand side away from the roll bite, A cold rolling method characterized by forming a plate-out layer.
L ≧ V in ・ T min (However, L is the mounting position of the spray header from the roll bite (m), V in Is the entry strip speed (m / sec), t min Represents the required minimum phase inversion time (sec). )
[0019]
The principle of the first invention will be described below.
[0020]
The position of the emulsion spray nozzle as close as possible to the upstream stand away from the roll bite is to secure the time for the emulsion to plate out (hereinafter referred to as the phase inversion time), thereby adhering the steel plate. This is based on the test result that the amount is increased and the lubricity is improved.
[0021]
FIG. 4 shows the mounting position of the spray header for supplying the emulsion. The header A is a supply header for a general lubricating coolant of a circulating rolling oil supply system, and is installed in the immediate vicinity of the roll bite. In the headers B and C, the attachment position of the header A is moved to be 1 m and 3 m away from the roll bite. In addition, the header A 'is a conventional header that supplies an emulsion having a higher concentration than the circulating rolling oil supply system to the lower surface side of the steel plate closest to the roll bite, separately from the circulating rolling oil supply system.
[0022]
FIG. 5 shows the average value of the amount of oil adhering to the steel sheet on the upper surface side and the lower surface side on the rolling mill exit side when the steel sheet is rolled using the respective headers. The amount of oil adhering to the steel plate was measured by a method (solvent extraction method) in which the oil content on the steel plate surface was extracted with an organic solvent such as hexane and the amount of oil extracted was measured. Using beef tallow as rolling oil, an emulsion having an oil concentration of 3.5% and an average particle size of 9 μm was supplied at a rate of 3400 L / min from headers A, B, and C of a circulating rolling oil supply system. In addition to the header A, an emulsion having an average particle size of 9 μm and a concentration of 10% was supplied from the header A ′ to the lower surface of the steel plate at a rate of 200 L / min. According to this result, as the header mounting position is moved away from the roll bite, the amount of oil adhering to the steel plate increases and the lack of lubrication tends to be resolved. In addition, when header A ′ is used in combination with header A, the amount of oil adhering to the steel plate is slightly increased compared to the case where header A is used alone, but it is equivalent to header B. It can be seen that the amount of oil is high and the effect of improving lubricity is great.
[0023]
The above-described results are related to a phenomenon in which the plate-out property of the emulsion rolling oil depends on the time after spraying.
[0024]
FIG. 6 shows in detail the process of separating oil from water and forming an oil film (plate-out layer) when emulsion rolling oil is sprayed onto the strip. When a so-called O / W type emulsion in which oil droplets are dispersed in water is jetted onto the surface of the strip, the oil droplets in the emulsion are first subjected to pressure by colliding with the surface of the strip, and then the relative velocity with the strip O / W type emulsion becomes W / 0 type (water droplets are dispersed in oil) due to shearing and physical adsorption with the strip with increased temperature and in some cases evaporation of water. Phase inversion into emulsion or oil monolayer. This is thought to produce a plate-out layer. This process does not occur instantaneously when sprayed, but is caused by a transition process (reaction) such as phase inversion under the above-described mechanical conditions and temperature conditions, and thus is considered to be a time-dependent process. Needless to say, the time required for this may be short, but in any case requires a certain amount of time. The inventors considered that the time for phase inversion, that is, the phase inversion time has a great influence on the plate-out property.
[0025]
  Further, the inventors further performed the plate-out test and the rolling-out property of the emulsion rolling oil by a plate-out test method shown in FIG. 7 (a method of spraying the rolling oil and then blowing off the rolling oil that does not plate out by air blow after a predetermined time). The relationship between phase times was investigated. FIG. 8 shows the result. According to this, the plate-out amount greatly depends on the phase inversion time, and when the phase inversion time is increased, the plate-out amount increases. In addition, when the phase inversion time becomes shorter than tmin in the figure, the plate-out amount rapidly decreases. Therefore, it is preferable to ensure a phase inversion time of tmin or more.“Minimum phase inversion time T min "Means the phase inversion time necessary to ensure 250 mg / m2 as the plate-out amount. When the plate-out amount is 250 mg / m 2 or more, the amount of oil on the roll bite entry side is a sufficient amount of adhesion, and is an amount that enables relatively stable rolling even in the high-speed rolling region.
[0026]
From the above results, the method of supplying the emulsion just before biting the roll bite performed in the prior art cannot secure the phase inversion time, and thus a sufficient plate-out layer cannot be formed. Especially in the high-speed rolling zone, the time to plate out becomes extremely short, so in the method of supplying emulsion just before the bite bite as in the prior art, almost improved lubricity even if the emulsion concentration is high. There is no effect.
[0027]
On the other hand, according to the present invention, the position of the spray nozzle is close to the upstream stand away from the roll bite, and the phase inversion time is secured, so that a sufficient plate-out layer is formed even when using an emulsion with a low circulation system concentration. Therefore, lubricity in the high-speed rolling region can be ensured. The header is preferably attached at a position where at least the minimum phase inversion time tmin obtained from the plate-out test can be secured. Accordingly, the distance L (m) from the emulsion supply position to the roll bite is determined so as to satisfy the following formula.
[0028]
L ≧ Vin · tmin Equation (1)
(However, Vin represents the inlet strip speed (m / sec), and tmin represents the minimum required phase inversion time (sec).)
Moreover, FIG. 9 shows the relationship between the rolling speed and the steel plate adhesion oil amount on the delivery side of the rolling mill in the 5-stand cold rolling mill, but in the high speed rolling zone, not only the steel plate lower surface side but also the steel plate adhesion oil amount on the upper surface side. Has also decreased. This is related to a phenomenon in which the emulsion plate-out depends on the phase inversion time until the emulsion is sprayed and plate-out. That is, the emulsion that does not plate out on the lower surface side of the copper plate immediately drops, but the effective amount of supplied rolling oil increases on the upper surface side of the steel plate because the sprayed emulsion stays on the steel plate surface. Therefore, the amount of adhesion on the upper surface side is usually higher in the low-speed rolling region than on the lower surface side, but the plate-out amount is the same as that on the lower surface in the high-speed rolling region because the phase inversion time is shortened until the emulsion is sprayed out To decrease. Therefore, it is necessary to sufficiently improve the slipperiness on both the upper and lower surfaces by spraying on the upper and lower surfaces even in the high-speed rolling region.
[0029]
In the above, the case of using a circulating rolling oil supply system has been described, but the principle of the present invention can also be applied to a cold tandem rolling mill using a direct rolling oil supply system.
[0030]
2nd invention supplies the emulsion which is excellent in plate-out property with high adhesion efficiency adjusted so that it might become an average particle diameter larger than the emulsion of a circulating rolling oil supply system. This is based on the following examination results.
[0031]
That is, as a result of intensive studies on means for improving the adhesion efficiency of the emulsion when the emulsion is supplied to the steel sheet, the inventors have found that the adhesion efficiency is greatly improved when the emulsion average particle size is increased. The result of investigating the relationship between the average particle size of the emulsion and the deposition efficiency by the plate-out test method shown in FIG. 7 is shown in FIG. 10, and the deposition efficiency increases as the average particle size increases. In particular, when the average particle size is 20 μm or more, the adhesion efficiency increases rapidly.
[0032]
FIG. 11 shows the relationship between the amount of emulsion supplied and the amount of oil adhering to the steel sheet when spraying the emulsion rolled oil having an average particle diameter of 20 μm and the emulsion rolled oil having an average particle diameter of 9 μm on the steel sheet surface from the spray header C shown in FIG. It is the result of investigating. At this time, beef tallow was used as the base oil, and it was an emulsion rolling oil having an oil concentration of 3.5%, and the average particle diameter of the emulsion was adjusted by the number of revolutions of a stirrer installed in the tank.
[0033]
According to this, by using an emulsion rolling oil having an average particle diameter of 20 μm, the amount of oil adhered to the steel sheet was larger than that of an emulsion rolling oil having an average particle diameter of 9 μm. This can improve the lubricity in the high-speed rolling region even when a small amount of emulsion is supplied by using emulsion rolling oil with high adhesion efficiency and large average particle diameter.
[0034]
However, if the particle size of the emulsion is increased, the emulsion stability is impaired, so that it is not suitable as an emulsion of a circulating rolling oil supply system. For example, when wear powder generated by rolling, iron powder brought into the steel plate, or the like is mixed in the circulating coolant, an emulsion having a large average particle diameter is easily broken, so that the emulsification dispersibility easily changes with time. Along with this, problems such as destabilization of rolling and changes in glossiness of the steel sheet surface become problems.
[0035]
Therefore, in order to use an emulsion having a large average particle size as an emulsion for lubrication, a second rolling oil supply system is provided separately from the circulating rolling oil supply system, and the rolling oil crude oil, the surfactant, and the dilution water are newly added. It is necessary to prepare an emulsion having a large average particle diameter.
[0036]
According to a third aspect of the present invention, in the cold rolling method using a tandem rolling mill for steel plates using a circulating rolling oil supply system, a second rolling oil supply system is provided separately from the circulating rolling oil supply system, and the circulating rolling oil is provided. Rolling is performed by spraying an emulsion with high adhesion efficiency adjusted to a particle size larger than the supply system (for example, 20 μm) on the steel plate at a position on the upstream stand side away from the roll bite and adjusting the supply amount. It is a method to prevent chattering during high speed rolling by controlling the inside advanced rate within the target advanced rate range.
[0037]
FIG. 17 shows the occurrence of chattering and No. 5 in all 5 stand tandem mills. This shows the relationship between the five stands' advanced rate, but it can be seen that there is a stable advanced rate range where chattering does not occur. The advanced rate can be said to be an index representing the rolling lubrication state when the rolling conditions such as the rolling reduction and tension are the same. Chattering that occurs in a high advanced rate region of 1% or more is due to insufficient lubrication, and chattering that occurs in a low advanced rate region of 0% or less is due to excessive lubrication. Chattering.
[0040]
As a result of earnestly examining the method for adjusting the coolant supply amount to control the target advanced rate, the inventors can devise a method for taking a large change range of the advanced rate with respect to the change of the coolant supply amount. I got new knowledge.
[0041]
One has found that the range of change of the advanced rate by changing the coolant supply amount can be widened by setting the mounting position of the coolant header as close as possible to the upstream stand far from the roll bite.
[0042]
  FIG.These show the attachment position of the header at the time of the test in the same test as FIG. The spray header A is a supply header for a general lubricating emulsion in a circulating rolling oil supply system, and is installed in the immediate vicinity of the roll bite. The spray headers B and C were positioned 1.0 m and 3.5 m away from the roll bite, respectively. The distance between the stands is 4.5 m. Figure19Shows the relationship between the amount of emulsion supplied during testing and the advanced rate, but as the spray header mounting position is moved away from the roll bite and closer to the upstream stand, the range of change in the advanced rate due to the change in coolant supply becomes wider. I can see that Figure20Is the result of investigation of the amount of oil adhering to the steel sheet on the surface of the rolled material at this time. The amount of oil adhering to the steel sheet corresponds to the advanced rate, and increases as the spray header mounting position is moved away from the roll bite and closer to the upstream stand side.
[0043]
The reason is as follows. That is, by spraying the emulsion onto the steel plate on the upstream stand side away from the roll bite, it is possible to secure a phase inversion time for the sprayed emulsion to plate out on the steel plate surface, thereby increasing the plate-out amount. For this reason, if the emulsion supply amount is changed, the friction coefficient changes greatly. Along with this, the range of change of the advanced rate becomes wider. In particular, in the high-speed rolling zone, the time for the emulsion to plate out is shortened. Therefore, it is effective to make the header position as upstream as possible from the roll bite.
[0044]
In the present invention, the header is installed at a position on the upstream stand side away from the roll bite, the emulsion supply amount to be sprayed on the steel sheet is adjusted, and the advanced rate during rolling is controlled within the target range. Is based.
[0045]
  Furthermore, as a result of intensive studies, it has been found that the use of an emulsion having an average particle size larger than that of the circulating rolling oil supply system is more effective. Figure21When using beef tallow as rolling oil, adding a cationic dispersant as a surfactant and using it as an emulsion with the same average particle size of 10 μm as the circulation system, and when using an emulsion with a larger average particle size of 20 μm The relationship between the emulsion supply amount and the advanced rate is shown. The spray header at this time is18The middle spray header C was used. The average particle size of the emulsion was adjusted by adjusting the amount of surfactant added and mechanical stirring conditions. According to this, in the case of an emulsion having an average particle diameter of 20 μm, it can be seen that even if a small amount of emulsion is supplied, the change range of the advanced rate can be taken large. Also figure22Is a measurement result of the amount of oil adhering to the surface of the rolled material, which corresponds to the advanced rate, and when using an emulsion having an average particle size of 20 μm, the amount of oil adhering greatly increases.
[0046]
  Figure23Indicates the relationship between the change rate of the advanced rate and the average emulsion particle size when the emulsion supply rate is changed in the range of 0 to 100 L / min, but the change rate of the advanced rate as the average particle size increases In particular, when the average particle size is 20 μm or more, the change range of the advanced rate is rapidly expanded.
[0047]
This is because, as the average particle size of the emulsion increases, the plate-out amount increases, so the change in the friction coefficient with respect to the change in the emulsion supply amount increases, and the change in the advance rate also increases accordingly. .
[0048]
As described above, in the cold tandem rolling mill equipped with the circulating rolling oil supply system, the change range of the advanced rate by changing the coolant supply amount can be increased by using the coolant supply method according to the present invention. For this reason, in the high-speed rolling zone, by changing the coolant supply amount using the advanced rate as an index, the target advanced rate that does not cause chattering due to insufficient lubrication and chattering due to excessive lubrication is achieved. Since it can be controlled, chattering can be prevented.
[0049]
[Embodiments of the Invention]
(Embodiment 1) FIG. 1 is an example of equipment for carrying out the method of the first invention, and is applied to the fourth stand and the fifth stand of all five tandem mills. The reason why the 4th and 5th stands are applied is that the rolling speed is higher as the later stage stands, and the plate thickness becomes thinner, so the rolling load becomes higher, the strict lubrication conditions become higher, and the occurrence frequency of heat scratches becomes higher. is there. FIG. 1-No. 5 shows an arrangement example of a tandem rolling mill having 5 (# 1STD to # 5STD) stands, 1 is a work roll, 2 is a backup roll, 3 is a strip, 4a is a conventional coolant coolant header, and 4b is a coolant coolant header. 5, No. 5 according to the present invention. This is a coolant header for lubrication on the 4th and 5th stand entrance side. The lubrication coolant header 5 is positioned such that the distance L from the roll bit satisfies formula (1) and is as far as possible from the roll bit, and the phase inversion time for the emulsion supplied to the steel plate surface to plate out. To ensure the maximum. The minimum phase inversion time tmin is obtained by a plate-out test shown in FIG. In the case of beef tallow-based emulsion, tmin is 0.12 sec from FIG. When the maximum rolling speed is 2000 mpm, No. Assuming that the rolling reduction ratios of the 4th and 5th stands are 35% and 30%, respectively, the entry side strip speed of each stand is 910 mpm and 1400 mpm. Therefore, the distance L from the roll bit to the header mounting position is No. No. 2.8m or more is required for 5 stands. Here, it was immediately after the area affected by the roll / strip cooling coolant header 4b on the exit side of the front stand (1.0 m from the exit side of the front stand), and was installed at a position of 3.5 m from the entrance side roll bite. The distance between the stands is 4.5 m.
[0050]
(Embodiment 2) FIG. 2 is an example of equipment for carrying out the second invention method, and is applied to the fourth stand and the fifth stand of all five tandem mills. In addition, the arrangement | positioning of a spray header is the same as that of FIG. 1 shown in the said Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
[0051]
The hot water, the rolled oil crude oil, and the surfactant are supplied from the tanks 7, 8, and 9 through the supply pumps 10a, 10b, and 10c, respectively, and the flow rate adjusting valve 11a so as to have a predetermined oil concentration and surfactant concentration against the oil. 11b, 11c, the replenishment amount is adjusted and supplied to the emulsion storage tank 6. The emulsion concentration in the tank, the oil concentration of the surfactant, and the emulsion temperature are the same as those in the circulating rolling oil supply system. The average particle size of the oil in the tank is an emulsion having an average particle size larger than that of the circulating rolling oil supply system by adjusting the rotation speed of the agitator 12. For example, when the base oil is beef tallow and a cationic dispersion type surfactant is added to the emulsifying dispersant at an oil concentration of 0.6%, the average particle size of the emulsion of the circulating rolling oil system is about 9 to 10 μm. It becomes. On the other hand, the average particle diameter in the tank 6 is adjusted to be 30 to 50 μm.
[0052]
The emulsion rolling oil having a large average particle diameter is supplied by the pump 13 to the upper and lower surfaces of the strip from the spray header 5 via the rolling oil supply line 14. The emulsion particle size at this time is sheared by the pump 13 and the nozzle portion of the spray header 5 and becomes an average particle size of 20 to 40 μm.
[0053]
After spraying on the steel plate, the emulsion that does not plate out on the steel plate is collected together with the circulating emulsion for cooling in the recovery oil pan 15 and mixed in the circulating rolling oil supply tank 17 via the return line 16. . After mixing, the mixture is stirred by the stirrer 18 in the tank, and is subdivided to the same particle size as the circulating emulsion, resulting in a tight emulsion.
[0054]
(Embodiment 3) FIG. 16 shows an example of equipment for carrying out the method of the third invention, which is applied to all 5 stand tandem rolling mills. As a result of the investigation, no. The occurrence frequency of chattering using 5 stands as a trigger stand is high. It was confirmed that application to 5 stands was effective. Based on this result, FIG. 1 to 4 stands are lubricated by a circulating first rolling oil supply system. The case where 5 stand lubrication is performed by the second rolling oil supply system according to the present invention will be described. In addition, No. The roll cooling of 1 to 5 stands is performed by spraying the emulsion of the circulation system onto the rolls on the exit side of each stand.
[0055]
Hot water, rolled oil crude oil, and surfactant are supplied to the emulsion storage tank 6 from the tanks 7, 8, 9 via the supply pumps 10 a, 10 b, 10 c. The replenishment amount at this time is adjusted by the valve opening degree of the flow control valves 11a, 11b, and 11c. The stirring condition of the stirrer 12 in the tank and the addition amount of the surfactant are adjusted to prepare an emulsion having a large average particle size (for example, 20 μm or more). The emulsion concentration is the same as or higher than that of the emulsion of the circulating first rolling oil supply system.
[0056]
[0054]
The emulsion liquid of the second rolling oil supply system is supplied from the header 5a and the header 5b to the steel sheet surface via the supply pipe 14 by the pump 13. The headers 5a and 5b should be No. as much as possible. It is desirable to install it at a position close to 4 stands. Here, no. It was installed at a position 3.5 m away from the roll bite immediately after the influence range of roll cooling on the 4 stand exit side (1 m from No. 4 stand).
[0057]
The emulsion flow rate sprayed onto the steel sheet is adjusted by the opening degree of the valve 30. The advanced rate of 5 stands is set to be within a stable range where chattering does not occur.
[0058]
Below, the setting method of a valve opening is shown.
[0059]
(1) The rotation speed of the work roll measured by the pulse generator 32 and the plate speed measured by the plate speedometer 33 on the stand exit side are substituted into the equation (2). Obtain the advanced rate during rolling of 5 stands.
[0060]
[Expression 1]

[0061]
However, fs (%): advanced rate, Vs (m / min): plate speed, D (m): work roll diameter, n (rpm): roll rotational speed (2) Deviation from the target advanced rate is expressed by the equation (3) )
[0062]
[Expression 2]

[0063]
Where Δfs (%): deviation from the target advanced rate, fs (%): advanced rate during rolling, fs^*(%): Target advanced rate
The target advanced rate is determined based on a survey of a stable advanced rate range in which chattering does not occur as shown in FIG.
[0064]
(3) The change amount ΔQ of the emulsion supply amount of the second rolling oil supply system is calculated from the equation (4).
[0065]
[Equation 3]

[0066]
However, ΔQ (L / min) is a change amount of the emulsion supply amount, Δfs (%) is a deviation between the advanced rate during rolling and the target advanced rate, and ∂fs / ∂μ (% / −) is relative to the advanced rate fs. The influence coefficient ∂μ / ∂Q (− / L / min) of the friction coefficient μ is an influence coefficient of the emulsion supply amount Q with respect to the friction coefficient μ.
[0067]
∂fs / ∂μ is given by, for example, a derivative equation (5) regarding the friction coefficient μ in the advanced rate equation of Bland & Ford.
[0068]
[Expression 4]

[0069]
[Equation 5]

[0070]
Where μ is the coefficient of friction during rolling, km (kg / mm² ) Is the average deformation resistance of the rolled material, H (mm), h (mm) is the thickness at the entry / exit side, σb (kg / mm)² ), Σf (kg / mm² ) Represents the front / rear unit tension during rolling, and R ′ (mm) represents the roll flat radius.
[0071]
For the average deformation resistance km and the friction coefficient μ during rolling, the measured loads P and fs during rolling are substituted into Hill's rolling load equation (7) and Bland & Ford's advanced rate equation (8). Ask.
[0072]
[Formula 6]

[0073]
[Expression 7]

[0074]
However, W (mm) represents a sheet width, P (ton) represents a rolling load during rolling, and fs (%) represents an advanced rate during rolling.
[0075]
Further, ∂μ / ∂Q is determined based on rolling experiments and data collected in operation. An example is shown below.
[0076]
The relationship between the emulsion supply amount and the playout oil film thickness PΦ is expressed by Expression (9) as a result of the investigation by the plate-out test.
[0077]
[Equation 8]

[0078]
Where PΦ is the plate-out oil film thickness (μm), c is the emulsion concentration (%), f is the emulsion adhesion efficiency (%), Q is the emulsion supply rate (L / min), W is the spray width (m), and Vs is It represents the steel plate speed (m / min) of the spray part.
[0079]
Further, the friction coefficient μ is expressed by the equation (10) as a function of the ratio between the plate-out oil film thickness PΦ and the surface roughness Λ of the work roll.
[0080]
[Equation 9]

Here, n and m are constants, and Λ is the surface roughness (μm) of the work roll.
[0081]
Substituting equation (9) into equation (10) and calculating the derivative of emulsion feed rate Q yields equation (11).
[0082]
[Expression 10]

[0083]
However, Q (L / min) is the emulsion supply amount, c (%) is the emulsion concentration, f (%) is the emulsion adhesion efficiency, w (m) is the spray width, and Vs (m / min) is the steel plate speed of the spray section. , Λ (μm) is the surface roughness of the work roll, and a, m, n are constants.
[0084]
(4) The flow rate is controlled by changing the valve opening degree of the flow rate control valve 30 according to ΔQ.
[0085]
On the other hand, the emulsion of the circulating rolling oil supply system is supplied from the tank 17 through the pump 19 and the pipe 20 to the roll bite entry side as the lubricating oil from the headers 4a and 4a. Moreover, it supplies to a stand exit side roll from header 4b, 4b as cooling. Thereafter, the oil is recovered by the oil pan 15 and returns to the tank 17 via the pipe 16.
[0086]
【Example】
(Embodiment 1) FIG. 3 shows the coolant for lubrication of the embodiment 1 (FIG. 1), in particular, the # 4 and # 5 stands, in which the present invention is applied to the fourth and fifth stands of a cold tandem rolling mill with 5 stands. This shows details of the header arrangement. Using a 5-stand tandem mill with such a header arrangement, the header used, the emulsion concentration and the thickness when a hard tin plate having a base material thickness of 1.8 mm and a plate width of 900 mm was cold-rolled to a final thickness of 0.183 mm. Table 1 shows combinations of emulsion supply amounts. In addition, beef tallow emulsion (base oil viscosity 40 cSt, emulsion temperature 60 ° C. at 40 ° C.) was used as rolling oil. In FIG. 3, 1 is a coolant coolant header (header B) according to the present invention, 2 is a conventional coolant coolant header (header A), and 3 is another system of the prior art (Japanese Patent Publication No. 59-24858). The coolant header for lubrication is shown.
[0087]
[Table 1]

[0088]
Rolling was performed under the above conditions while changing the rolling speed, and the amount of oil adhering to the steel sheet and the friction coefficient of the fifth stand were investigated. FIG. 12 shows the relationship between the rolling speed and the amount of oil adhering to the steel sheet, and FIG. 13 shows the relationship between the rolling speed and the friction coefficient of the fifth stand, comparing the present invention with the conventional method 1 and the conventional method 2. The amount of oil adhering to the steel plate was determined by a method (solvent extraction method) in which the oil content on the steel plate surface was extracted with an organic solvent such as hexane and the amount of oil extracted was measured.
[0089]
In the conventional method 1, the amount of steel sheet attached decreased on both the front and back surfaces in a speed range of 800 mpm or more. Further, in the conventional method 2, the amount of adhered steel plate is increased only at the back surface at 1000 mpm, but the amount of adhered oil rapidly decreased in a high speed region of 1200 mpm or more. Correspondingly, the friction coefficients in the conventional method 1 and the conventional method 2 increased in the high-speed rolling region, and chattering occurred due to insufficient lubrication at speeds of 1200 mpm and 1500 mpm, respectively.
[0090]
On the other hand, in the present invention, a stable steel plate adhesion oil amount was obtained even at a high speed range of 1200 mpm or more on both the front and back surfaces. As a result, an increase in the friction coefficient of the fifth stand is suppressed, and a stable friction condition is obtained up to the high speed range. In particular, there is almost no increase in the coefficient of friction at high speeds, and chattering caused by insufficient lubrication does not occur.
[0091]
(Example 2) Using the same 5-stand tandem mill as in Example 1, a soft tin plate having a base material thickness of 2.3 mm and a plate width of 900 mm was cold-rolled to a final thickness of 0.183 mm. The emulsion properties and supply amount are the same as in Table 1. The target rolled material of this example is softer than the target rolled material of Example 1, but has a high cold pressure ratio, and when rolled by a conventional circulating rolling oil supply system, the fifth stand having a particularly high rolling speed. In Japan, heat scratches occurred frequently.
[0092]
Rolling was performed under the above conditions while changing the rolling speed, and the amount of oil adhering to the steel sheet and the friction coefficient of the fifth stand were investigated. FIG. 14 shows the relationship between the rolling speed and the friction coefficient of the fifth stand, and FIG. 15 shows the relationship between the rolling speed and the steel plate temperature on the outlet side of the fifth stand, including the state of occurrence of heat scratch defects. In both cases, the present invention is compared with the conventional method 1 and the conventional method 2. The friction coefficients of the conventional method 1 and the conventional method 2 increased in the high speed rolling region. The temperature of the steel plate at the 5th stand has increased significantly with the speed in the conventional method 1 and the conventional method 2, with 1500 mpm in the conventional method 1 and over 170 ° C. at 1700 mpm or more in the conventional method 2, and heat scratching occurs. did.
[0093]
On the other hand, in the case of the present invention, an increase in the friction coefficient of the fifth stand is suppressed, and a stable friction condition is obtained up to the high speed range. In particular, the coefficient of friction hardly increased at high speeds. As described above, according to the present invention, since the increase in the friction coefficient in the high-speed rolling zone can be suppressed, the frictional heat generation is reduced, and as a result, the steel plate temperature is lowered, so that heat scratch flaws are not generated.
[0094]
(Example 3) No. of tandem rolling mill of all 5 stands. Using Embodiment 2 (FIG. 2) in which the second invention is applied to 4 and 5 stands, a hard tin plate having a base material thickness of 1.8 mm and a plate width of 900 mm as in Example 1 is cold-finished to a finish thickness of 0.183 mm. Rolled. The beef tallow emulsion (base oil viscosity 40 cSt, emulsion temperature 60 ° C. at 40 ° C.) is used as the rolling oil, and the emulsion concentration, average particle size and supply amount are as shown in Table 2. This is a condition in which the emulsion concentration is the same, the emulsion average particle size is large, and the emulsion supply amount is small compared to Example 1 of the first invention.
[0095]
  Rolling was performed while changing the rolling speed under the above conditions, and the amount of oil adhering to the steel sheet and the friction coefficient of the fifth stand were investigated. Figure26Figure 3 shows the relationship between rolling speed and the amount of oil adhering to the steel sheet.27Shows the relationship between the rolling speed and the friction coefficient of the fifth stand. According to the third aspect of the invention, as in Example 1 according to the first aspect of the invention, a stable amount of oil adhering to the steel sheet was obtained even at a high speed range of 1200 mpm or more on both the front and back surfaces. As a result, an increase in the friction coefficient of the fifth stand is suppressed, and a stable friction condition is obtained up to the high speed range. In particular, there is almost no increase in the coefficient of friction at high speeds, and chattering caused by insufficient lubrication does not occur.
[0096]
[Table 2]

[0097]
  (Example 4) Comparison between test results conducted to confirm the effect of the present invention and a conventional circulating rolling oil supply system24Shown in The rolling conditions and emulsion conditions are as follows.
[0098]
<Rolling conditions>-Rolled steel type-Tin plate size-Base material thickness 1.8mm, Finish thickness 0.183mm, Plate width 900mm-Work roll: Φ600mm 5 stand reduction rate 30%
[Table 3]

[0099]
  Figure24(A) is No. during rolling. Relationship between advanced rate of 5 stands and rolling speed, figure24(B) is the relationship between the emulsion supply amount and rolling speed according to the present invention, FIG.24(C) shows the relationship between the emulsion supply rate and the rolling speed according to the prior art. When the present invention is used, the emulsion supply amount is as low as 90 L / min up to 1000 mpm, and increases with speed after 1000 mpm. By performing such supply amount control, the advanced rate during rolling is controlled to the target advanced rate (0.3 to 0.4% at 1000 mpm or more), so that stable rolling is possible and chattering is not generated. It was able to accelerate to 2000 mpm. On the other hand, when the conventional circulating rolling oil supply system was used, the advanced rate began to increase with the speed after 1000 mpm. On the other hand, although the emulsion supply amount was increased from 2000 L / min to 340 L / min, chattering occurred outside the stable advanced rate range at 1500 mpm. For this reason, acceleration of 1500 mpm or more was impossible.
[0100]
From the above results, it can be seen that by using the present invention, chattering can be prevented because it is possible to control to a stable advanced rate range in a high speed region and to confirm an appropriate lubrication state.
[0101]
  The distribution of rolling speed when rolling a hard thin tin plate with a finishing thickness of 0.21 mm or less using the present invention is compared with the case of a conventional circulating rolling oil supply system.25Shown in By using the present invention, since the occurrence frequency of chattering that occurs in a high speed region is reduced, the average rolling speed can be improved from 1500 mpm to 1900 mpm.
[0102]
【The invention's effect】
As described above, according to the first invention and the second invention, in the cold rolling method of a steel sheet using a circulating rolling oil supply system, a direct supply system of emulsion having a high concentration of 10% or more is used. The amount of oil adhering to the steel sheet in the high-speed rolling zone can be greatly improved. This eliminates the lack of lubrication that has occurred during high-speed rolling, prevents the occurrence of heat scratches, and improves the rolling speed, thereby greatly improving productivity. Moreover, since damage to the roll can be prevented, additional effects such as improvement of the roll basic unit due to the improvement of the roll life can be expected.
[0103]
According to the third invention, an emulsion having a large average particle diameter is supplied from the second rolling oil supply system to a steel plate position where the phase inversion time for plate-out can be ensured to the maximum, and the supply amount is adjusted. As a result, the advanced rate can be controlled in a wide range even in the high-speed rolling zone, and control to the target advanced rate without chattering becomes possible. As a result, chattering can be prevented from occurring, so that high-speed rolling is possible and productivity is greatly improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an application example to a tandem rolling mill according to a first embodiment of the present invention.
FIG. 2 is a diagram showing an application example to a tandem rolling mill according to a second embodiment of the present invention.
FIG. Arrangement of 4 and 5 stand coolant coolant headers.
FIG. 4 is a diagram showing a header mounting position during a test.
FIG. 5 is a view showing a measurement result of the amount of oil adhering to a steel plate.
FIG. 6 is a schematic diagram of a generation process of a plate-out layer.
FIG. 7 is a diagram showing a plate-out test method.
FIG. 8 is a relationship diagram of phase inversion time and deposition efficiency.
FIG. 9 is a relationship diagram between the amount of oil adhering to the steel sheet and the rolling speed.
FIG. 10 is a graph showing the relationship between the average emulsion particle size and the adhesion efficiency.
FIG. 11 is a diagram showing the relationship between the emulsion supply amount and the steel plate adhesion oil amount.
FIG. 12 is a diagram showing a comparison of the amount of oil adhering to the steel plate of the present invention and the conventional method.
FIG. 13 is a diagram showing a comparison of friction coefficients between the present invention and a conventional method.
FIG. 14 is a view showing a comparison of friction coefficients between the fifth stand of the present invention and a conventional method.
FIG. 15 is a view showing a comparison of steel plate temperatures on the outlet side of the fifth stand according to the present invention and the conventional method.
FIG. 16 is a diagram showing an application example of the inventive method of claim 3;
FIG. 17 is a diagram showing the relationship between chattering occurrence and advanced rate.
FIG. 18 is a diagram showing a header mounting position during a test.
FIG. 19 is a graph showing the relationship between the emulsion supply amount and the advanced rate.
FIG. 20 is a diagram showing the relationship between the emulsion supply amount and the steel plate adhesion oil amount.
FIG. 21 is a graph showing the relationship between the emulsion supply amount and the advanced rate.
FIG. 22 is a diagram showing the relationship between the emulsion supply amount and the steel plate adhesion oil amount.
FIG. 23 is a graph showing the relationship between the average emulsion particle size and the change range of the advance rate.
FIG. 24 is an explanatory diagram of the effect of the invention of claim 3, (a) shows the relationship between the broken line new rate and the rolling speed, (b) shows the emulsion flow rate of another rolling oil strong break or the like according to the present invention, c) shows the emulsion flow rate of the prior art.
FIG. 25 is a diagram showing a comparison of rolling speed distributions.
FIG. 26 is a diagram showing the relationship between the rolling speed and the steel plate oil adhesion amount, where (a) shows the front surface and (b) the steel plate oil adhesion amount on the back surface.
27 shows rolling speed and No. The figure which shows the relationship of the friction coefficient of 5 stands.
[Explanation of symbols]
1. . . Work rolls,
2. . . Backup roll,
3. . . strip,
4a. . . Coolant header for lubrication,
4b. . . Coolant header for cooling,
5). . . Coolant header for lubrication,
6). . . Storage tank for emulsions with large average particle size,
7). . . Hot water tank,
8). . . Rolling oil crude oil tank,
9. . . Surfactant tank,
10a, 10b, 10c. . . pump,
11a, 11b, 11c. . . valve,
12 . . Agitator,
13. . . Emulsion supply pump,
14 . . Rolling oil supply line,
15. . . Recovered oil pan,
16. . . Return piping,
17. . . A circulating first rolling oil supply tank;
18. . . Agitator,
19. . . Emulsion supply pump,
20. . . Rolling oil supply line,
30. . . valve,
31. . . Control device,
32. . . Pulse generator,
33. . . Plate speedometer on the stand exit side.

Claims (1)

In a cold rolling method of a steel plate that performs high-speed rolling at 1200 mpm or more using a circulating rolling oil supply system, directly on the upper and lower surfaces of the steel plate at a position satisfying the following formula on the upstream stand side away from the roll bite A cold rolling method comprising spraying an emulsion to form plate-out layers on both upper and lower surfaces of a steel plate.
L ≧ Vin · tmin (where L is the spray header mounting position (m) from the roll bite, Vin is the inlet strip speed (m / sec), and t min is the required minimum phase inversion time (sec)).

Images