JP3937061B2 - Cold rolling oil - Google Patents

Description

【００２０】
ただし、Ｒ、Ｒ´は炭素数２〜８のアルキル基、アルケニル基、アリール基アルキルアリール基を示す」
【００２１】
【発明の実施の形態】
以下、本発明実施の形態について説明する。
【００２２】
本発明の冷間圧延油は、潤滑性向上剤としてのチオ燐酸化合物と、水溶化助剤兼増粘剤としての多価アルコールおよび水より構成される。それら成分の限定条件について説明する。
【００２３】
１）チオ燐酸化合物
潤滑性向上剤として使用するもので、下記の（Ａ）、（Ｂ）で表されるチオ燐酸化合物が使用できる。
【００２４】
【化１】

【００２５】
ただし、Ｒ、Ｒ´は炭素数２〜８のアルキル基、アルケニル基、アリール基アルキルアリール基のいずれかを示す。
【００２６】
ここで、チオ燐酸化合物の炭素数を２〜８としたのは、２未満では被圧延材の金属板に吸着する分子膜の厚みが薄く耐焼付き性が十分でなく、一方８を超えると水に溶解しにくくなるためである。
【００２７】
好適なチオ燐酸化合物は以下の通りである。
【００２８】
（Ａ）の化合物
エチルチオ燐酸アンモニウム、 プロピレンチオ燐酸アンモニウム
ブチルチオ燐酸アンモニウム、 フェニルチオ燐酸アンモニウム
オクチルチオ燐酸アンモニウム、 ヘキシルチオ燐酸アンモニウム
２−エチルヘキシルチオ燐酸アンモニウム、
（Ｂ）の化合物
ジエチルチオ燐酸アンモニウム ジプロピレンチオ燐酸アンモニウム
ジブチルチオ燐酸アンモニウム、 ジフェニルチオ燐酸アンモニウム
ジヘキシルチオ燐酸アンモニウム、
ジ２−エチルヘキシルチオ燐酸アンモニウム、
これらは、何れも分子中のチオ燐酸基が被圧延材の金属板の表面に吸着し、強固な油膜を形成するので、ロールと被圧延材間の焼付きを防止する。
【００２９】
ここで、チオ燐酸のアンモニウム塩に限定したのは、Ｎａ塩、Ｋ塩等のアルカリ塩を用いると、冷間圧延後の焼鈍工程でそれらが灰分として残り、製品の品質を低下させるため好ましくなく、アンモニウム塩であれば灰分として残らないからである。
【００３０】
チオ燐酸化合物含有量は下記理由により１重量％（以下、％は重量比を示すものとする）以上とする。すなわち、１％未満では、たとえ増粘剤を添加して、ロールバイト内に冷間圧延油を保持させることができても、圧延により発生した鋼板表面全ての新生面に圧延油を吸着させて覆うことはできず焼付きが発生しやすい。より好ましい含有量は、５〜２５％未満である。２５％以上では水に完全に溶解するのが難しくなる。
【００３１】
２）炭素数６以下の多価アルコール
多価アルコールは、チオ燐酸化合物を水溶化する作用を有すると共に、チオ燐酸化合物の水溶液を増粘させる作用がある。
【００３２】
チオ燐酸化合物のみを水に添加して冷間圧延油とした場合、本発明の冷間圧延油は組成の大半が水であるので、冷間圧延油全体としての高圧粘度が極端に低くなる。そのため、圧延時に高圧になったロールバイト内では、冷間圧延油がロール、鋼板の粗さの隙間から流出してしまい、十分にチオ燐酸酸化合物をロールバイト内に保持できない。さらに、チオ燐酸酸化合物が水に完全に溶解しないで分散し、濃度むらを生じる。しかし、チオ燐酸酸化合物を水溶化助剤兼増粘剤としての多価アルコールにより溶解させることにより、全体としての高圧粘度が低粘度鉱油並みになり、圧延時のロールバイト内においてもロール、鋼板の表面の微細な凹凸の隙間から冷間圧延油が流出してしまうことなくロールバイト内に保持される。
【００３３】
したがって、圧延によって生じた板の新生面に対しても圧延油が保持されているので焼付きの発生を防止することができる
炭素数が６を超えた多価アルコールは水に対する溶解度が低く使用できないので炭素数を６以下とした。
【００３４】
好適な多価アルコールとしては、エチレングリコール、プロピレングリコール、ブタンジオール、ヘキサンジオール、ジエチレングリコール、ネオペンチルグリコール、グリセリン、トリメチロールプロパン、ペンタエリスリトール等を挙げることができる。
【００３５】
これらの物質は、分子中のアルコール性水酸基が水中で水素結合して粘度を高める作用がある。また、これらの多価アルコールは、潤滑性向上剤として添加しているチオ燐酸化合物が加水分解を起こしチオ燐酸を生じた場合、これをエステル化する作用がある。特にエチレングリコール、グリセリンが好ましい。
【００３６】
この水溶化助剤兼増粘剤の含有量は、５％未満では高圧粘度が低過ぎ、ロールバイト内での冷間圧延油の保持が不十分となるので、下限を５％とした。また、本発明にかかる増粘剤と潤滑性向上剤の総量は５０％以下とする必要がある。増粘剤と潤滑性向上剤の総量が５０％を超えると水の含有量が少なすぎるため、冷却性能が急激に低下してしまう。また、水の蒸発による水の含有量変化が多く性能が安定しない。より好ましい範囲は、２５〜４０％である。
【００３７】
３）水
圧延油の水の含有量は、冷却性能と難燃性を確保するためには５０％以上とする必要がある。また、金属の冷間圧延では、加工熱により被圧延材やロールの温度が上昇するため、圧延油中の水が蒸発し潤滑剤の濃度むらが生じ、被圧延材の光沢むらの原因にもなるので、この観点からも５０％以上とする必要がある。好ましくは６０〜７５％である。
【００３８】
本発明の冷間圧延油は、上記のチオ燐酸化合物と多価アルコールをあらかじめ混合しておいたものを、圧延油の使用条件に応じて適宜の水に添加して攪拌、溶解するなどの方法で調整してもよく、また最初から所定濃度の水に溶解させておいて使用してもよい。
【００３９】
冷間圧延油の供給方法としては、そのまま、或いは高濃度に調整したものを水で希釈して、スプレー塗布、ウォーターインジェクションおよびエアアトマイズなどの方法により冷間圧延工程に供給して使用できる。
【００４０】
特に高速圧延を行う場合は、水の濃度を高くして供給することにより潤滑性、冷却性能に優れ、かつ光沢が良好となる。また、従来のエマルション型圧延油や、含水タイプの圧延油で問題となるような光沢むらなども生じない。
【００４１】
本発明の冷間圧延油は、圧延ロールの材質がＳＫＤ１１、Ｃｒメッキロール、ハイスおよび超硬などの何れであっても使用することがきる。また、適用される被圧延材も特に限定されず、ステンレス鋼、炭素鋼などの圧延材に使用できる。
圧延ロール材質と圧延材の組み合わせも特に制限されない。
【００４２】
本発明の冷間圧延油は、水を５０％以上含有しているため難燃性であり、また脂肪酸等を含んでいなく粘土も適度であるため比熱が水並に高く、従来の冷間圧延油に比べて冷却性能がかなり良好である。Ｏ／Ｗエマルションタイプの冷間圧延油と比較しても同等以上の冷却性能を有する。
【００４３】
さらに、チオ燐酸化合物が完全に水に溶けているので、油膜厚さが不均一になるといった問題も生じることがなく、また、水の量が５０ｗｔ％以上と多いため水の蒸発による光沢むらなども生じない。
【００４４】
【実施例】
次に具体的な実施例に基づき本発明の効果について説明する。
【００４５】
先ず、表１に示す本発明例の圧延油番号１〜２１と表２、３に示す比較例の圧延油番号１〜７および従来例としての圧延油番号８、９の２８種類の冷間圧延油を準備した。ここで従来例９はＯ／Ｗ型エマルションタイプの冷間圧延油であり、ホモミキサーで油分平均粒径を約４μmに調整した。
【００４６】
【表１】

【００４７】
【表２】

【００４８】
【表３】

【００４９】
上記冷間圧延油について下記の条件で圧延をおこない、圧延油の評価を行った。
【００５０】
使用した圧延機は下記の４段式圧延機（ツインドライブ）であった。
【００５１】
ワークロール ：直径１００ｍｍ、バレル長さ３００ｍｍ
バックアップロール：直径２００ｍｍ、長さ３００ｍｍ
圧延最高速度 ：４００ｍ／分
被圧延材は、光沢度（Ｇｓ４５゜）７００の熱延後酸洗済みの板厚２ｍｍ、板幅５０ｍｍ、長さ３００ｍのフェライト系ステンレス鋼ＳＵＳ４３０−２Ｄ、および光沢度（Ｇｓ４５゜）１５０の熱延後酸洗済みの炭素鋼（ＳＰＣＣ−ＳＢ）のコイルを用いた。
【００５２】
圧延方法は、１パス目は、圧延速度２００ｍ／分、２パス目は３００ｍ／分、３パス目は、４００ｍ／分とし、圧下率はＳＵＳ４３０−２Ｄについては１パス２５％、ＳＰＣＣ−ＳＢについては１パス３５％でそれぞれ連続３パスの圧延を行った。
【００５３】
圧延ロールは、バレル部を表面粗さ０．０１μm Ｒａに仕上げた、ＳＫＤ１１およびセミハイス（０．４％Ｃ、５％Ｃｒ、１％Ｍｏ、３％Ｖ、１％Ｗ）からなる２種類のロールを用いた。また、各潤滑剤は圧延機の入り側でロールおよび鋼板に直接、圧力５kgf／ｃｍ²、流量６■／分で供給した。
【００５４】
圧延油の潤滑性の評価は、３パス圧延後の鋼板表面の焼付きの有無でおこなった。また、光沢性の評価は、表面光沢度（Ｇｓ４５°）で行い、光沢度が７００以上を良好とする。
【００５５】
表４にＳＵＳ４３０を、表５に炭素鋼を圧延した結果を示す。焼付き発生有無に関しては、焼付きが全く生じなかった場合を○印として耐焼付き性良好とし、焼付きが生じた場合を×印で表した。さらに、ＳＫＤ１１ロールでＳＵＳ４３０を圧延した際の３パス圧延直後のコイル表面温度を併せて表５に示した。
【００５６】
【表４】

【００５７】
【表５】

【００５８】
この結果から、本発明の冷間圧延油を用いることによって、ＳＵＳ４３０、炭素鋼の何れを圧延してもロールおよび鋼板表面温度の上昇が抑制でき、焼付きの発生も完全に防止できることが確認できた。さらには、本発明の冷間圧延油では、エマルションタイプの冷間圧延油に見られるような光沢むらも全く発生しなかった。
【００５９】
なお、比較例５、７ではチオ燐酸化合物が水に溶解せず均一にならなかったため耐焼付き性、光沢むら共に悪い結果になった。また、ＳＫＤ１１ロール、セミハイスロールのどちらでも同じ効果が得られた。
【００６０】
【発明の効果】
本発明の冷間圧延油によれば、鋼板の破断時に発生する火災の危険性もなく、高速圧延を行っても焼付きを生じず、表面光沢の良好な鋼板を製造できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cold rolling oil used for cold rolling of a metal plate such as a steel plate, and is particularly suitable for high-speed cold rolling of a stainless steel plate, having excellent lubricity and roll cooling properties, and having high gloss after rolling. It relates to the cold rolling oil from which the steel plate of this is obtained.
[0002]
[Prior art]
The most important performance required for cold rolling oil of metal sheets is lubricity, but in addition, various performances are required from the viewpoint of product quality and maintenance. For example, in the cold rolling of a stainless steel plate, the gloss of the product surface is most important. This is because stainless steel is excellent in corrosion resistance and is used for a part that is directly touched for decoration or the like without surface treatment. This gloss is greatly affected by the lubrication state during rolling.
[0003]
During rolling, depressions called oil pits are formed on the surface of the steel sheet after rolling by the oil pressure of the oil film formed between the roll and the steel sheet (generally called “inside the roll tool”). When the oil film thickness is thick or when the viscosity of the rolling oil under high pressure (hereinafter referred to as high pressure viscosity) is high, the amount of oil pits generated increases and the surface gloss of the steel sheet decreases.
To explain this state in detail, first, since the metal being rolled causes plastic deformation, the interface between the roll and the steel sheet is in a high pressure state that is higher than the deformation resistance of the material to be rolled, and naturally the rolling oil present therein is also, It is thought that it is in a high pressure state.
[0004]
When rolling using high-pressure viscous rolling oil, the fluidity of the rolling oil is low, so it is easily contained in the space created by the fine surface irregularities of the roll and steel plate in the roll bite, forming an oil pit. . However, when rolling oil with low high-pressure viscosity is used, it has high fluidity even under high pressure, so it flows out from the gap between the roughness of the roll and the steel plate to the lower pressure before being sealed, and oil pits are formed. Hateful. However, if the viscosity is too low, the fluidity will be too high, so it will flow out of the roll bite through the gap between the roll and the steel plate, and no oil film will be formed in the roll bite, resulting in insufficient lubrication. .
[0005]
Therefore, in cold rolling of a stainless steel plate, rolling oil having a low high-pressure viscosity and a small amount drawn into the roll bite is used. Mineral oil with a low viscosity is one that satisfies this condition. However, low-viscosity mineral oil has poor lubricity and tends to cause seizure. Therefore, in order to improve seizure resistance, synthetic esters, fatty acid alcohols, and the like are added as oils. However, even if these are added, mineral oil and synthetic ester have low specific heat, and the cooling performance of the roll and the steel sheet is poor, so that the temperature of the roll and the steel sheet surface rises during high-speed rolling. When the temperature rises, the oil component is thermally decomposed or detached from the roll and the steel sheet surface, and the lubricity is lowered and seizure occurs.
[0006]
Cooling performance is improved by further reducing the viscosity of cold-rolled oil to increase fluidity, but mineral oil lowers its flash point as the viscosity decreases, so a fire occurs due to a spark when a plate breaks. There is a risk of occurrence, and there is a limit to lowering the viscosity.
[0007]
On the other hand, as a cold rolling oil excellent in flame retardancy and cooling properties, there is an oil-in-water dispersion (O / W) type emulsion rolling oil conventionally used for rolling oil of ordinary steel. However, the O / W emulsion type cold rolled oil is excellent in cooling performance because most of its components are water, while the amount of oil adhering to the roll and the steel sheet surface tends to be uneven and causes uneven gloss. is there.
[0008]
JP-A-60-118799 discloses a lubricant for metal working such as stainless steel in which a lubricant is dissolved in 1 to 50% by weight of water. The cooling performance is not extremely improved like / W type emulsion. Further, moisture is evaporated and reduced due to processing during high-speed rolling and frictional heat, and uneven gloss occurs due to partial changes in viscosity, cooling performance, and the like. Furthermore, if the evaporation of water increases, sufficient flame retardancy cannot be obtained.
[0009]
There is a demand for the development of rolling oil that has stable flame retardancy and lubricity, and that provides high gloss to the rolled metal sheet.
[0010]
[Problems to be solved by the invention]
It is an object of the present invention to provide a cold rolling oil that can produce a metal plate having high surface gloss without causing seizure or fire even when high-speed rolling is performed.
[0011]
[Means for Solving the Problems]
As a result of various experimental studies aimed at developing a cold rolling oil that has excellent lubricity and cooling performance in high-speed rolling, and is capable of producing a flame-retardant and high-surface gloss metal plate, the following results were obtained. I came to get a good knowledge.
[0012]
a) Conventional emulsion-type cold rolling oil has oil particles non-uniformly present in an oil film adhering to a roll or a steel plate, which becomes a heat transfer resistance and lowers cooling performance.
[0013]
b) In order to improve the cooling performance, it is preferable to use only a substance that completely dissolves in water and to make water 50% or more.
[0014]
c) Ammonium thiophosphate, when dissolved in water, forms a strong oil film and exhibits excellent lubricity.
[0015]
d) However, since ammonium thiophosphate is difficult to dissolve in water and has a low viscosity under high pressure, the ammonium thiophosphate is easily dissolved in water (hereinafter referred to as water solubilization), and the aqueous solution is thickened. It is better to add a polyhydric alcohol for this purpose.
[0016]
The present invention has been made based on such findings, and the gist thereof is as follows.
[0017]
“At least one thiophosphoric acid compound represented by the following general formulas (A) and (B) and at least one polyhydric alcohol having 6 or less carbon atoms are dissolved in water in an amount within the following range. Cold-rolled oil, characterized by
[0018]
(1) Thiophosphoric acid compound: 1% by weight or more (2) Polyhydric alcohol: 5% by weight or more and the total amount of (1) and (2) is less than 50% by weight
[Chemical 1]

[0020]
However, R and R 'represent a C2-C8 alkyl group, an alkenyl group, an aryl group, an alkylaryl group "
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0022]
The cold rolling oil of the present invention is composed of a thiophosphoric acid compound as a lubricity improver, a polyhydric alcohol as a water solubilizer and thickener, and water. The limiting conditions for these components will be described.
[0023]
1) A thiophosphate compound used as a lubricity improver, and thiophosphate compounds represented by the following (A) and (B) can be used.
[0024]
[Chemical 1]

[0025]
However, R and R ′ represent any of an alkyl group having 2 to 8 carbon atoms, an alkenyl group, and an aryl group and an alkylaryl group.
[0026]
Here, the reason why the thiophosphate compound has 2 to 8 carbon atoms is that if it is less than 2, the thickness of the molecular film adsorbed on the metal plate of the material to be rolled is thin and the seizure resistance is not sufficient. It is because it becomes difficult to melt | dissolve.
[0027]
Suitable thiophosphoric acid compounds are as follows.
[0028]
Compound (A) ammonium ethylthiophosphate, ammonium propylenethiophosphate ammonium butylthiophosphate, ammonium phenylthiophosphate ammonium octylthiophosphate, ammonium hexylthiophosphate 2-ethylhexylthiophosphate ammonium
Compound (B) ammonium diethylthiophosphate ammonium dipropylenethiophosphate ammonium dibutylthiophosphate, ammonium diphenylthiophosphate ammonium dihexylthiophosphate,
Ammonium di-2-ethylhexylthiophosphate,
In any of these, since the thiophosphate group in the molecule is adsorbed on the surface of the metal plate of the material to be rolled and forms a strong oil film, seizure between the roll and the material to be rolled is prevented.
[0029]
Here, the limitation to the ammonium salt of thiophosphoric acid is not preferable because when alkali salts such as Na salt and K salt are used, they remain as ash in the annealing process after cold rolling, which lowers the quality of the product. This is because an ammonium salt does not remain as ash.
[0030]
The content of the thiophosphoric acid compound is 1% by weight (hereinafter,% indicates a weight ratio) or more for the following reason. That is, if it is less than 1%, even if a thickener is added and the cold rolling oil can be retained in the roll bite, the rolling oil is adsorbed and covered on all new surfaces of the steel plate surface generated by rolling. It is not possible to seize. A more preferable content is 5 to less than 25%. If it is 25% or more, it becomes difficult to dissolve completely in water.
[0031]
2) Polyhydric alcohol having 6 or less carbon atoms Polyhydric alcohol has an action of water-solubilizing the thiophosphoric acid compound and an action of thickening an aqueous solution of the thiophosphoric acid compound.
[0032]
When only a thiophosphoric acid compound is added to water to form a cold rolling oil, the cold rolling oil of the present invention is mostly water, so the high-pressure viscosity of the entire cold rolling oil becomes extremely low. Therefore, the cold rolling oil flows out from the gap between the roll and the steel plate in the roll bite that has become high pressure during rolling, and the thiophosphate compound cannot be sufficiently retained in the roll bite. Further, the thiophosphoric acid compound is dispersed without completely dissolving in water, resulting in uneven concentration. However, by dissolving the thiophosphoric acid compound with a polyhydric alcohol as a water-solubilizing aid and thickener, the high-pressure viscosity as a whole becomes the same as that of a low-viscosity mineral oil. The cold rolling oil does not flow out of the gaps between the fine irregularities on the surface of the steel, and is retained in the roll bite.
[0033]
Therefore, since the rolling oil is retained even on the new surface of the plate produced by rolling, the polyhydric alcohol having a carbon number exceeding 6 that can prevent the occurrence of seizure has low solubility in water and cannot be used. The carbon number was 6 or less.
[0034]
Suitable polyhydric alcohols include ethylene glycol, propylene glycol, butanediol, hexanediol, diethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol and the like.
[0035]
These substances have the effect of increasing the viscosity by alcohol bonding of alcoholic hydroxyl groups in the molecule in water. Further, these polyhydric alcohols have an action of esterifying a thiophosphoric acid compound added as a lubricity improver when it is hydrolyzed to produce thiophosphoric acid. In particular, ethylene glycol and glycerin are preferable.
[0036]
When the content of the water solubilizing aid / thickening agent is less than 5%, the high-pressure viscosity is too low, and the cold rolling oil is not sufficiently retained in the roll bite. Therefore, the lower limit is set to 5%. Further, the total amount of the thickener and the lubricity improver according to the present invention needs to be 50% or less. If the total amount of the thickener and the lubricity improver exceeds 50%, the water content is too small and the cooling performance is drastically lowered. In addition, the water content changes due to water evaporation and performance is not stable. A more preferable range is 25 to 40%.
[0037]
3) The water content of the water rolling oil needs to be 50% or more in order to ensure cooling performance and flame retardancy. Also, in cold rolling of metal, the temperature of the material to be rolled and the roll rises due to the processing heat, so the water in the rolling oil evaporates, causing uneven concentration of the lubricant, which also causes uneven gloss of the material to be rolled. Therefore, it is necessary to make it 50% or more also from this viewpoint. Preferably it is 60 to 75%.
[0038]
The cold rolling oil of the present invention is a method in which the above-mentioned thiophosphoric acid compound and polyhydric alcohol are mixed in advance and added to appropriate water depending on the usage conditions of the rolling oil, followed by stirring and dissolution. Or may be used after being dissolved in water of a predetermined concentration from the beginning.
[0039]
As a method for supplying the cold rolling oil, it can be used as it is or after being diluted to a high concentration with water and supplied to the cold rolling step by a method such as spray coating, water injection and air atomization.
[0040]
In particular, when high-speed rolling is performed, the lubricity and the cooling performance are excellent and the gloss is improved by supplying the water at a high concentration. Further, there is no uneven luster that would be a problem with conventional emulsion-type rolling oil or water-containing type rolling oil.
[0041]
The cold rolling oil of the present invention can be used regardless of whether the material of the rolling roll is SKD11, Cr plating roll, high speed steel or carbide. Further, the material to be rolled is not particularly limited, and can be used for rolled materials such as stainless steel and carbon steel.
A combination of the rolling roll material and the rolling material is not particularly limited.
[0042]
The cold-rolled oil of the present invention is flame retardant because it contains 50% or more of water, and since it does not contain fatty acids or the like and clay is moderate, the specific heat is as high as water. Cooling performance is considerably better than rolling oil. Even when compared with O / W emulsion type cold rolling oil, it has a cooling performance equal to or higher than that.
[0043]
Furthermore, since the thiophosphoric acid compound is completely dissolved in water, there is no problem that the oil film thickness becomes non-uniform. Does not occur.
[0044]
【Example】
Next, effects of the present invention will be described based on specific examples.
[0045]
First, 28 types of cold rolling of rolling oil numbers 1 to 21 of the present invention examples shown in Table 1, rolling oil numbers 1 to 7 of comparative examples shown in Tables 2 and 3, and rolling oil numbers 8 and 9 as conventional examples. Prepared the oil. Here, Conventional Example 9 is an O / W type emulsion type cold rolling oil, and the oil average particle size was adjusted to about 4 μm with a homomixer.
[0046]
[Table 1]

[0047]
[Table 2]

[0048]
[Table 3]

[0049]
The cold rolling oil was rolled under the following conditions to evaluate the rolling oil.
[0050]
The rolling mill used was the following four-stage rolling mill (twin drive).
[0051]
Work roll: Diameter 100mm, barrel length 300mm
Backup roll: diameter 200mm, length 300mm
Maximum rolling speed: 400 m / min Rolled material is ferritic stainless steel SUS430-2D having a thickness of 2 mm, a plate width of 50 mm, and a length of 300 m after hot-rolling with a gloss (Gs 45 °) of 700, and glossiness A coil of carbon steel (SPCC-SB) that had been hot-rolled (Gs 45 °) 150 and then pickled was used.
[0052]
The rolling method is a rolling speed of 200 m / min for the first pass, 300 m / min for the second pass, 400 m / min for the third pass, and the rolling reduction is 25% for 1 pass for SUS430-2D and for SPCC-SB. Each rolled three consecutive passes at 35% per pass.
[0053]
The rolling rolls are two types of rolls consisting of SKD11 and semi-high speed (0.4% C, 5% Cr, 1% Mo, 3% V, 1% W) with the barrel portion finished to a surface roughness of 0.01 μm Ra. Was used. Each lubricant was directly supplied to the roll and the steel plate at the entrance of the rolling mill at a pressure of 5 kgf / cm ² and a flow rate of 6 I / min.
[0054]
The evaluation of the lubricity of the rolling oil was performed based on the presence or absence of seizure on the steel sheet surface after the 3-pass rolling. Further, the glossiness is evaluated based on the surface glossiness (Gs 45 °), and the glossiness is 700 or more.
[0055]
Table 4 shows the results of rolling SUS430, and Table 5 shows the results of rolling carbon steel. With respect to the presence or absence of seizure, a case where no seizure occurred was marked with a mark “◯” to indicate good seizure resistance, and a case where seizure occurred was represented with a “x” mark. Further, Table 5 shows the coil surface temperature immediately after the 3-pass rolling when SUS430 was rolled with the SKD11 roll.
[0056]
[Table 4]

[0057]
[Table 5]

[0058]
From this result, by using the cold rolling oil of the present invention, it can be confirmed that the roll and steel plate surface temperature can be prevented from rising even if either SUS430 or carbon steel is rolled, and seizure can be completely prevented. It was. Furthermore, the cold rolling oil of the present invention did not cause any uneven gloss as seen in emulsion type cold rolling oil.
[0059]
In Comparative Examples 5 and 7, the thiophosphoric acid compound did not dissolve in water and was not uniform, so both the seizure resistance and the gloss unevenness were poor. In addition, the same effect was obtained with both the SKD11 roll and the semi-high roll.
[0060]
【The invention's effect】
According to the cold rolling oil of the present invention, there is no risk of fire that occurs when a steel sheet is ruptured, and even when high-speed rolling is performed, seizure does not occur and a steel sheet with good surface gloss can be produced.

Claims (1)

At least one thiophosphoric acid compound represented by the following general formulas (A) and (B) and at least one polyhydric alcohol having 6 or less carbon atoms are dissolved in water in an amount within the following range. Cold rolling oil characterized by
(1) Thiophosphoric acid compound: 1% by weight or more (2) Polyhydric alcohol: 5% by weight or more and the total amount of (1) and (2) is less than 50% by weight

However, R and R ′ represent any of an alkyl group having 2 to 8 carbon atoms, an alkenyl group, an aryl group, and an alkylaryl group.