JPH08226086A - Extra fine steel wire excellent in corrosive fatigue characteristic and corrosion resistance - Google Patents

Abstract

PURPOSE: To produce an extra fine steel wire maintaining a twisting characteristic, enhanced in excellent corrosion resistance and corrosive fatigue characteristic, and useful as an extra fine steel wire capable of being twisted into a steel cord or miniature rope used for reinforcing a tire or belt, by specifying the shape of its cross section to prevent galvanic corrosion. CONSTITUTION: This extra fine steel wire has a cross section outer shape line expressed by an arbitrary closed curve belonging to a region formed between a closed curved obtained by turning back a curve expressed by a below- described equality [1] on the X and Y axes and a closed curve obtained by turning back a curve expressed by a below-described equality [2] on the X and Y axes, and has an (a)/(b) ratio of 1.05-5.0 and a (2a) of <=1.0mm. (x<10> /a<10> )+(y<10> /b<10> )=-1...[1], (x<1.2> /a<1.2> )+(y<1.2> /b<1.2> )=-1...[2] (0<=x<=a and 0<=y<=b; when (x) is 0, (y) is (b), and when (y) is 0, (x) is (a)).

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、タイヤやベルト等のゴ
ム補強用あるいはミニチュアロープ等の撚線製造用の強
化用線材として使用される極細鋼線に関し、殊にその腐
食疲労特性と耐食性を改善した極細鋼線に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrafine steel wire used as a reinforcing wire material for reinforcing rubber such as tires and belts or for producing twisted wires such as miniature ropes, and particularly to its corrosion fatigue characteristics and corrosion resistance. It relates to an improved ultrafine steel wire.

【０００２】[0002]

【従来の技術】例えばタイヤ補強用等として使用される
鋼線材としては、従来よりＪＩＳ ＳＷＲＳ ７２Ａや
ＳＷＲＳ ８２Ａなどの炭素鋼が使用されており、その
代表的な製造法を示すと下記の通りである。即ち、所定
の化学組成を有する鋼材を熱間圧延した後必要に応じて
調整冷却し、得られた線材に１次伸線加工、パテンティ
ング処理、２次伸線加工、再度のパテンティング処理を
順次行ない、その後ゴム等との接着性改善のため真鍮な
どの銅合金系めっきを施した後、最終的に仕上げ伸線加
工を加えて極細鋼線とされる。そして該極細鋼線を、そ
の用途に応じて複数本撚り合わせることによって補強用
のスチールコードとされる。2. Description of the Related Art For example, as a steel wire rod used for reinforcing a tire, carbon steel such as JIS SWRS 72A or SWRS 82A has been conventionally used, and its typical manufacturing method is as follows. is there. That is, after hot rolling a steel material having a predetermined chemical composition, if necessary, cooling is adjusted, and the obtained wire material is subjected to primary wire drawing, patenting, secondary wire drawing, and patenting again. Sequentially, and then copper alloy plating such as brass is applied to improve adhesion with rubber, etc., and finally final drawing is applied to obtain ultrafine steel wire. Then, a plurality of the ultrafine steel wires are twisted together according to the use to form a reinforcing steel cord.

【０００３】ところで、この様なスチールコードを例え
ばタイヤ用強化材等として使用した場合、タイヤゴム中
に含まれる水分あるいはタイヤゴムの亀裂部等から浸入
してくる水分その他の腐食性物質によってスチールコー
ドが腐食を受け、比較的短期間のうちに強化効果が低下
するという問題がある。そこで、スチールコードの腐食
劣化を抑制しタイヤ寿命を延長させる為の方法として、
スチールコードの素線材に窒化処理などを施すことによ
って腐食疲労特性を高める方法（特開平３−４４９２３
号）、素線材の成分組成や撚り構造を工夫することによ
り耐食性を高める方法（特開平２−５３９８１号）、極
細鋼線の断面形状を偏平化することによって耐疲労特性
や耐食性を向上させる方法（特開昭６３−１７６７０２
号）等が提案されている。By the way, when such a steel cord is used as a reinforcing material for a tire, for example, the steel cord is corroded by moisture contained in the tire rubber or moisture or other corrosive substances infiltrating from cracks of the tire rubber. Therefore, there is a problem that the strengthening effect is reduced in a relatively short period of time. Therefore, as a method to suppress corrosion deterioration of steel cord and extend tire life,
A method for enhancing corrosion fatigue characteristics by subjecting a steel cord wire material to nitriding treatment, etc. (JP-A-3-44923)
No.), a method of improving corrosion resistance by devising the component composition and twist structure of the wire material (JP-A-2-53981), and a method of improving fatigue resistance and corrosion resistance by flattening the cross-sectional shape of the ultrafine steel wire. (JP-A-63-176702)
No.) etc. have been proposed.

【０００４】これらの方法によれば、スチールコードの
耐疲労特性や耐食性をある程度高めることができ、それ
によりスチールコード強化タイヤの寿命をかなり延長す
ることができるが、それでも一層の寿命延長を求める最
近の需要者の要求を満足するものとはいえない。According to these methods, the fatigue resistance and corrosion resistance of the steel cord can be enhanced to some extent, and thereby the life of the steel cord reinforced tire can be considerably extended. Can not be said to satisfy the demands of consumers.

【０００５】[0005]

【発明が解決しようとする課題】本発明は上記の様な事
情に着目してなされたものであって、その目的は、タイ
ヤ強化用のスチールコード等として使用される極細鋼線
の耐疲労特性や耐食性を一段と高め、強化タイヤとして
の寿命や安全性を更に高めることのできる技術を提供し
ようとするものであり、具体的には、極細鋼線の形状面
からの腐食要因を追求し、タイヤ補強用はもとより、ベ
ルト強化用あるいはミニチュアロープ用等として優れた
耐疲労特性と耐食性を発揮し得る様な極細鋼線を提供し
ようとするものである。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is the fatigue resistance of an ultrafine steel wire used as a steel cord for reinforcing a tire. It aims to provide a technology that can further improve the corrosion resistance and corrosion resistance to further enhance the life and safety of a reinforced tire. Specifically, in pursuit of corrosion factors from the shape surface of the ultrafine steel wire, The present invention intends to provide an ultrafine steel wire capable of exhibiting excellent fatigue resistance and corrosion resistance not only for reinforcement but also for belt reinforcement or miniature rope.

【０００６】[0006]

【課題を解決するための手段】上記課題を達成すること
のできた本発明に係る極細鋼線の構成は、めっき処理が
施された極細鋼線において、横断面の外形線が、下記式
［１］で表わされる曲線をＸ軸およびＹ軸で折り返して
得られる閉曲線と、下記式［２］で表わされる曲線をＸ
軸およびＹ軸で折り返して得られる閉曲線との間の領域
に属する任意の閉曲線で表わされ、且つａ／ｂを１．０
５〜５．０、２ａを１．０ｍｍ以下としたものであると
ころに要旨を有するものである。 （ｘ¹⁰／ａ¹⁰）＋（ｙ¹⁰／ｂ¹⁰）＝１ ……［１］ （ｘ^1.2 ／ａ^1.2 ）＋（ｙ^1.2 ／ｂ^1.2 ）＝１……［２］ 但し、０≦ｘ≦ａかつ０≦ｙ≦ｂ ｘ＝０のときｙ＝ｂ，ｙ＝０のときｘ＝ａThe structure of the ultrafine steel wire according to the present invention that has been able to achieve the above object is as follows. ] The closed curve obtained by folding back the curve represented by the X-axis and the Y-axis, and the curve represented by the following formula [2] by X
It is represented by an arbitrary closed curve belonging to the region between the axis and the closed curve obtained by folding back along the Y axis, and a / b is 1.0
5 to 5.0, 2a is 1.0 mm or less, and has a gist. ^{(X 10 / a 10) +} (y 10 / b 10) = 1 ...... [1] (x 1.2 / a 1.2) + (y 1.2 / b 1.2) = 1 ...... [2] where, 0 ≦ x ≦ a and 0 ≦ y ≦ b y = b when x = 0, x = a when y = 0

【０００７】上記本発明においては、極細鋼線の横断面
形状をその外形線が、下記式［３］で表わされる曲線を
Ｘ軸およびＹ軸で折り返して得られる閉曲線と、下記式
［４］で表わされる曲線をＸ軸およびＹ軸で折り返して
得られる閉曲線との間の領域に属する任意の閉曲線で表
わされるものとすることによって、耐疲労特性や耐食性
を一段と優れたものとすることができる。 （ｘ³ ／ａ³ ）＋（ｙ³ ／ｂ³ ）＝１ ……［３］ （ｘ^1.8 ／ａ^1.8 ）＋（ｙ^1.8 ／ｂ^1.8 ）＝１……［４］ 但し、０≦ｘ≦ａかつ０≦ｙ≦ｂ ｘ＝０のときｙ＝ｂ，ｙ＝０のときｘ＝ａIn the present invention, the outer shape of the cross-sectional shape of the ultra-fine steel wire is a closed curve obtained by folding the curve represented by the following formula [3] along the X-axis and the Y-axis, and the following formula [4]. The fatigue resistance and corrosion resistance can be made even more excellent by using the curve represented by ## EQU1 ## as an arbitrary closed curve belonging to the region between the closed curve obtained by folding back along the X axis and the Y axis. . (X ³ / a ³ ) + (y ³ / b ³ ) = 1 [3] (x ^1.8 / a ^1.8 ) + (y ^1.8 / b ^1.8 ) = 1 [4] where 0 ≦ x ≦ a and 0 ≦ y ≦ b y = b when x = 0, x = a when y = 0

【０００８】[0008]

【作用】タイヤ補強用として使用される極細鋼線の表面
には、前述の如くタイヤゴムとの接着力を担う真鍮等の
銅合金系めっき処理を施すのが通例であり、めっき処理
された極細鋼線に見られる水共存下での腐食は、めっき
層におけるピンホール部からの鋼のガルバニック腐食に
起因する孔食状の腐食ピットに応力集中が起こり、そこ
が起点となって腐食疲労破壊が進行するものと考えられ
る。[Function] As described above, the surface of the ultrafine steel wire used for reinforcing the tire is usually plated with a copper alloy such as brass that bears the adhesive force with the tire rubber. Corrosion observed in the wire in the presence of water causes stress concentration in the pit-like corrosion pit due to galvanic corrosion of steel from the pinhole in the plating layer, and the corrosion fatigue fracture progresses from that point. It is supposed to do.

【０００９】ところで、銅合金めっき材と鋼線との間で
生じるガルバニック腐食はカソード反応支配であるか
ら、鋼のガルバニック腐食を抑制するには、めっき層上
のカソード反応を抑制することが有効と考えられる。そ
こで本発明者らは、極細鋼線の腐食疲労破壊抑制手段と
して、この様なガルバニック腐食を低減させる方向で研
究を進めた。By the way, since the galvanic corrosion generated between the copper alloy plated material and the steel wire is governed by the cathodic reaction, it is effective to suppress the cathodic reaction on the plated layer in order to suppress the galvanic corrosion of the steel. Conceivable. Therefore, the inventors of the present invention have conducted research as a means for suppressing corrosion fatigue fracture of ultra-fine steel wire in the direction of reducing such galvanic corrosion.

【００１０】銅系合金と鋼がガルバニックカップルを組
んだときには、鋼がアノード（鉄の溶解反応）、銅系合
金めっき層がカソード（溶存酸素の還元反応）となるこ
とが知られており、この時の鋼の溶解速度は、夫々の分
極曲線における交点の電流密度によって表わされ、カソ
ード反応律速となる。ところで、平板状電極表面での溶
存酸素の還元反応は、溶存酸素の拡散律速であり、その
反応速度は下記式［５］で近似的に表わされる。 ｉ＝（ｎ・Ｆ・Ｄ・Ｃ^* ）／δ……［５］ ｉ：拡散限界電流密度 ｎ：電荷数 Ｆ：ファラデー定数 Ｄ：溶存酸素の拡散定数 Ｃ^* ：沖合いの酸素濃度 δ：見かけの拡散層の厚さIt is known that when a copper-based alloy and steel form a galvanic couple, the steel serves as an anode (dissolution reaction of iron) and the copper-based alloy plating layer serves as a cathode (reduction reaction of dissolved oxygen). The dissolution rate of the steel at that time is represented by the current density at the intersection of each polarization curve, and becomes the cathode reaction rate limiting. By the way, the reduction reaction of the dissolved oxygen on the surface of the flat plate electrode is diffusion limited rate of the dissolved oxygen, and the reaction rate is approximately represented by the following formula [5]. i = (n · F · D · C ^* ) / δ [5] i: Diffusion limit current density n: Number of charges F: Faraday constant D: Dispersion constant of dissolved oxygen C ^* : Offshore oxygen concentration δ: Apparent Thickness of diffusion layer

【００１１】これに対しフィラメントの様な円形断面の
極細線状電極の場合は、溶存酸素の拡散は線材の直径に
依存する。つまり、線状電極表面での拡散限界電流密度
（ｉ）は、線材の半径（ｒ）に依存し、近似的に下記式
［６］で表わすことができる。 ｉ＝（ｎ・Ｆ・Ｄ・Ｃ^* ）／［ｒ・ｌｎ（１＋δ／ｒ）］……［６］On the other hand, in the case of an ultrafine wire electrode having a circular cross section like a filament, the diffusion of dissolved oxygen depends on the diameter of the wire. That is, the diffusion limit current density (i) on the surface of the linear electrode depends on the radius (r) of the wire and can be approximately represented by the following formula [6]. i = (n · F · D · C ^* ) / [r · ln (1 + δ / r)] …… [6]

【００１２】即ちガルバニック腐食を考えると、平板状
物と線状物では腐食に影響する拡散限界電流密度（ｉ）
への依存度が若干異なり、今、たとえば図１に示す様に
線材の横断面形状が楕円状であるものを考えると、楕円
は曲率半径の異なる円周部の集合体であって、真円に比
べると曲率半径の大きな部分と小さな部分を有してお
り、楕円の曲率半径を全体で平均すると真円の半径
（ｒ）よりも大きくなる。こうした傾向を前記式［６］
に当てはめて考えると、同一横断面積の線材について真
円と楕円を比較した場合、横断面形状が楕円のものの方
が溶存酸素の拡散限界電流密度（ｉ）は小さくなり、そ
の結果腐食の反応律速となるカソード反応は抑えられる
と考えられる。In other words, considering galvanic corrosion, the diffusion limit current density (i) that affects the corrosion in flat and linear materials
Dependence on the wire diameter is slightly different, and now considering that the wire rod has an elliptical cross-sectional shape as shown in FIG. 1, an ellipse is an assembly of circumferential portions having different radii of curvature, and The radius of curvature of the ellipse is larger than the radius (r) of the true circle when compared with the radius of curvature of the ellipse. This tendency is expressed by the above formula [6].
When comparing a true circle and an ellipse for a wire having the same cross-sectional area, the diffusion limiting current density (i) of dissolved oxygen becomes smaller when the cross-sectional shape is elliptical, and as a result, the reaction rate control of corrosion is It is thought that the cathode reaction that becomes

【００１３】即ち、カソード反応に影響を及ぼす溶存酸
素の拡散限界電流密度（ｉ）は、真円状断面のものより
も楕円状断面のものの方が小さくなり、また楕円の長径
／短径比が大きくなる程（すなわち、偏平になる程）該
拡散限界電流密度（ｉ）は小さくなり、それに伴ってガ
ルバニック腐食も抑制され極細鋼線の耐食性は高められ
ると考えられる。That is, the diffusion limit current density (i) of dissolved oxygen which affects the cathode reaction is smaller in the elliptical cross section than in the perfect circular cross section, and the major axis / minor axis ratio of the ellipse is smaller. It is considered that the diffusion limit current density (i) becomes smaller as it becomes larger (that is, becomes flatter), and accordingly galvanic corrosion is also suppressed and the corrosion resistance of the ultrafine steel wire is enhanced.

【００１４】ところが、タイヤ強化用等として用いられ
る極細鋼線には、他の要求特性として捻回特性（多数の
極細鋼線を撚り合わせてスチールコードとするときの撚
合せ性と撚合せによる複合強化効果）があり、こうした
捻回特性を確保するには、横断面形状を過度に偏平な楕
円形状とすることはできない。However, the extra-fine steel wire used for reinforcing the tire has other required characteristics such as twisting characteristics (twistability when a large number of extra-fine steel wires are twisted together to form a steel cord, and a composite property due to the twisting). There is a strengthening effect), and in order to secure such twisting characteristics, it is not possible to make the cross-sectional shape into an excessively flat elliptical shape.

【００１５】そこで、こうした捻回特性を確保しつつガ
ルバニック腐食を効果的に抑制することのできる極細鋼
線の横断面形状を明らかにすべく鋭意研究を重ねた。本
発明はこうした研究の結果完成されたものであって、極
細鋼線の断面形状を工夫することにより、良好な捻回特
性を確保しつつガルバニック腐食に起因する腐食疲労破
壊を抑制しようとするものであり、具体的には、前述の
如く極細鋼線の横断面形状を、その外形線が、前記式
［１］で表わされる曲線をＸ軸およびＹ軸で折り返して
得られる閉曲線と、前記式［２］で表わされる曲線をＸ
軸およびＹ軸で折り返して得られる閉曲線との間の任意
の閉曲線で表わされる形状となる様に特定し、より好ま
しくはその外形線が、前記式［３］で表わされる曲線を
Ｘ軸およびＹ軸で折り返して得られる閉曲線と、前記式
［４］で表わされる曲線をＸ軸およびＹ軸で折り返して
得られる閉曲線との間の任意の閉曲線で表わされる形状
となる様に特定し、且つａ／ｂ、即ち長径（２ａ）と短
径（２ｂ）の比を１．０５〜５．０とすると共に２ａ、
即ち長径を１．０ｍｍ以下に設定するものである。Therefore, extensive studies have been conducted in order to clarify the cross-sectional shape of an ultrafine steel wire which can effectively suppress galvanic corrosion while ensuring such twisting characteristics. The present invention has been completed as a result of such research, and attempts to suppress corrosion fatigue fracture due to galvanic corrosion while ensuring good twisting characteristics by devising the cross-sectional shape of the ultrafine steel wire. Specifically, as described above, the cross-sectional shape of the ultra-fine steel wire, the outline of which is a closed curve obtained by folding back the curve represented by the above formula [1] on the X axis and the Y axis, and the above formula X is the curve represented by [2]
It is specified so as to have a shape represented by an arbitrary closed curve between the closed curve obtained by folding back along the axis and the Y axis, and more preferably, the contour line is the curve represented by the above formula [3] on the X axis and the Y axis. A closed curve obtained by folding back along the axis and a closed curve obtained by folding back the curve represented by the above formula [4] along the X axis and the Y axis are specified to have a shape represented by an arbitrary closed curve, and a / B, that is, the ratio of the major axis (2a) to the minor axis (2b) is 1.05 to 5.0 and 2a,
That is, the major axis is set to 1.0 mm or less.

【００１６】前記式［１］，［２］の設定式及びａ／ｂ
比や２ａが腐食疲労特性に与える影響については、後記
実施例で具体的に示すが、これらによって定める横断面
形状は例えば図２に示す通りである。即ち本発明では、
式［１］で表わされる曲線をＸ軸（水平対称）およびＹ
軸（鉛直対称）で折り返して得られる閉曲線と、式
［２］で表わされる曲線をＸ軸（水平対称）およびＹ軸
（鉛直対称）で折り返して得られる閉曲線との間（図２
の斜線領域）の任意の閉曲線で表わされ、且つ長径（２
ａ）と短径（２ｂ）の比、即ちａ／ｂが１．０５〜５．
０で、長径（２ａ）が１．０ｍｍ以下である断面形状を
表わしている。Setting equations of the above equations [1] and [2] and a / b
The influence of the ratio and 2a on the corrosion fatigue characteristics will be specifically shown in Examples described later, and the cross-sectional shape determined by these is as shown in FIG. 2, for example. That is, in the present invention,
The curve represented by the formula [1] is represented by X-axis (horizontal symmetry) and Y-axis.
Between the closed curve obtained by folding back along the axis (vertical symmetry) and the closed curve obtained by folding back the curve represented by the formula [2] along the X axis (horizontal symmetry) and the Y axis (vertical symmetry) (Fig. 2).
It is represented by an arbitrary closed curve in the shaded area of
a) to the minor axis (2b), that is, a / b is 1.05 to 5.
0 represents a cross-sectional shape in which the major axis (2a) is 1.0 mm or less.

【００１７】上記図２において、横断面形状の外形線が
斜線領域の内側もしくは外側に外れるものでは、楕円状
とすることによる前述のガルバニック腐食抑制効果が有
効に発揮されない。また長径／短径比（ａ／ｂ）が１．
０５未満のものでは、通常の真円形断面のものと殆んど
有意差が認められなくなる。一方、この比が５．０を超
え、あるいは長径（２ａ）が１．０ｍｍを超えると、本
発明で断面形状を上記の様に設定したことによる耐食性
向上効果が飽和してそれ以上の改善が期待できなくなる
ばかりでなく、極細鋼線の断面形状が偏平になり過ぎて
捻回特性が著しく悪くなり、タイヤ補強用等としての極
細鋼材に求められる要求適性を満足できなくなる。In FIG. 2, if the outer shape of the cross-sectional shape deviates inside or outside the shaded area, the above-mentioned galvanic corrosion suppressing effect due to the elliptical shape cannot be effectively exhibited. The ratio of major axis / minor axis (a / b) is 1.
When it is less than 05, almost no significant difference is recognized from that of a normal circular cross section. On the other hand, if this ratio exceeds 5.0 or the major axis (2a) exceeds 1.0 mm, the effect of improving the corrosion resistance by setting the sectional shape as described above in the present invention is saturated and further improvement is achieved. Not only can it not be expected, but the cross-sectional shape of the ultra-fine steel wire becomes too flat, and the twisting property is significantly deteriorated, and it becomes impossible to satisfy the required suitability required for the ultra-fine steel material for tire reinforcement and the like.

【００１８】尚、本発明でより好ましいものとして規定
する横断面形状は、図３に示す如く、式［３］で表わさ
れる曲線をＸ軸（水平対称）およびＹ軸（鉛直対称）で
折り返して得られる閉曲線と、式［４］で表わされる曲
線をＸ軸（水平対称）およびＹ軸（鉛直対称）で折り返
して得られる閉曲線との間（図３の斜線領域）の任意の
閉曲線で表わされ、且つ長径（２ａ）と短径（２ｂ）の
比、即ちａ／ｂが１．０５〜５．０で、長径（２ａ）が
１．０ｍｍ以下である断面形状を表わしており、該斜線
領域内に外形線を有する横断面形状の極細鋼線であれ
ば、優れた捻回特性を維持しつつガルバニック腐食抑制
効果をより効果的に発揮させることができ、タイヤ補強
用スチールコード等として非常に優れた特性を備えた極
細鋼線となる。The cross-sectional shape defined as more preferable in the present invention is as shown in FIG. 3, in which the curve represented by the formula [3] is folded back along the X axis (horizontal symmetry) and the Y axis (vertical symmetry). Expressed by an arbitrary closed curve between the obtained closed curve and the closed curve obtained by folding the curve represented by the formula [4] along the X axis (horizontal symmetry) and the Y axis (vertical symmetry) (hatched area in FIG. 3). And the ratio of the major axis (2a) to the minor axis (2b), that is, a / b is 1.05 to 5.0, and the major axis (2a) is 1.0 mm or less. An ultra-fine steel wire with a cross-sectional shape that has an outline in the area can effectively exhibit the galvanic corrosion inhibition effect while maintaining excellent twisting characteristics, and is extremely useful as a steel cord for tire reinforcement. It is an ultrafine steel wire with excellent properties.

【００１９】上記の様な横断面形状を有する極細鋼線
は、たとえば伸線加工、殊に最終仕上げ伸線加工時に使
用するダイスを目標横断面形状に応じた形状とすること
によって容易に制御することができる。The ultra-fine steel wire having the above-mentioned cross-sectional shape can be easily controlled by, for example, drawing a die used in the final drawing process, particularly in the final drawing process, so as to have a shape corresponding to the target cross-sectional shape. be able to.

【００２０】上記の様に本発明では、極細鋼線の横断面
形状を工夫することによって腐食環境下での溶存酸素の
拡散限界電流密度を小さくしてカソード反応を抑え、そ
の結果としてガルバニック腐食を抑制するものであり、
該鋼線材の成分組成等には一切制限がなく、先に示した
様なＪＩＳで規定される成分組成のものはもとより、そ
れらに成分組成等の面から改善を加えた公知の成分組成
のものを全て使用することができる。また該極細鋼線の
表面に施されるめっきの種類にも格別の制限はなく銅合
金めっき（銅−亜鉛系合金、銅−錫系合金、銅−ニッケ
ル系合金、銅−コバルト系合金、銅−亜鉛−コバルト系
合金、銅−ニッケル−亜鉛系合金等）、ニッケル系合金
めっき（ニッケル−燐系合金、ニッケル−コバルト系合
金等）などを全て採用できるが、最も一般的なのは真鍮
を始めとする銅系合金めっきであり、銅系合金めっきで
あれば、最終仕上げ伸線加工時に潤滑作用も発揮するの
で好ましい。めっき層の好ましい厚さは０．１〜１μｍ
程度である。As described above, in the present invention, by devising the cross-sectional shape of the ultrafine steel wire, the diffusion limiting current density of dissolved oxygen in a corrosive environment is reduced to suppress the cathode reaction, and as a result, galvanic corrosion is prevented. To suppress,
There is no limitation on the component composition of the steel wire rod, and not only those having the composition specified by JIS as described above but also those having the known composition that have been improved in terms of the composition etc. Can all be used. Further, there is no particular limitation on the type of plating applied to the surface of the ultrafine steel wire. Copper alloy plating (copper-zinc alloy, copper-tin alloy, copper-nickel alloy, copper-cobalt alloy, copper -Zinc-cobalt type alloys, copper-nickel-zinc type alloys, etc., nickel type alloy plating (nickel-phosphorus type alloys, nickel-cobalt type alloys, etc.) can all be adopted, but the most common one is brass. It is preferable that the copper-based alloy plating is performed because the copper-based alloy plating also exhibits a lubricating action during the final finish wire drawing. The preferable thickness of the plating layer is 0.1 to 1 μm
It is a degree.

【００２１】[0021]

【実施例】以下、実施例を挙げて本発明の構成および作
用効果をより具体的に説明するが、本発明はもとより下
記実施例によって制限を受けるものではなく、前・後記
の趣旨に適合し得る範囲で適当に変更を加えて実施する
ことも勿論可能であり、それらは何れも本発明の技術的
範囲に包含される。EXAMPLES Hereinafter, the constitution and working effects of the present invention will be described more specifically with reference to examples, but the present invention is not limited by the following examples, and is applicable to the gist of the preceding and the following. It is needless to say that appropriate modifications can be made within the range to be obtained, and they are all included in the technical scope of the present invention.

【００２２】実験例１ Ｃ：０．９０重量％、Ｓｉ：０．２１重量％、Ｍｎ：
０．４５重量％、Ｐ：０．００５重量％、Ｓ：０．００
６重量％、残部Ｆｅおよび不可避不純物からなる鋼材を
熱間圧延して線状に加工し、１次伸線加工、パテンティ
ング処理、２次伸線加工、再度のパテンティング処理、
真鍮めっきを順次施した後、最終工程で湿式伸線加工を
行ない、様々の横断面形状の極細鋼線を作製した。尚、
各極細鋼線の引張強度はほぼ一定（約３５０ｋｇ／ｍｍ
² ）となる様にした。各素線の横断面の形状特性を表１
に示す。Experimental Example 1 C: 0.90% by weight, Si: 0.21% by weight, Mn:
0.45% by weight, P: 0.005% by weight, S: 0.00
Steel material consisting of 6% by weight, balance Fe and unavoidable impurities is hot-rolled into a linear shape, and is subjected to primary wire drawing, patenting treatment, secondary wire drawing, and patenting again.
After brass plating was sequentially applied, wet drawing was performed in the final step to produce ultrafine steel wires with various cross-sectional shapes. still,
The tensile strength of each ultra-fine steel wire is almost constant (about 350 kg / mm
² ). Table 1 shows the shape characteristics of the cross section of each strand.
Shown in

【００２３】得られた各極細鋼線の夫々１本を用いて捻
回特性を調べ、また各極細鋼線５本を捻回せた各試料コ
ードをタイヤ用ゴム中に埋め込み、夫々の腐食疲労特性
と接着強度を調べた。The twisting characteristics of each of the obtained ultrafine steel wires were examined, and the sample cords obtained by twisting 5 of the ultrafine steel wires were embedded in the rubber for tires to obtain their corrosion fatigue characteristics. And the adhesive strength was examined.

【００２４】（捻回特性）ねじり試験機（島津製作所
製）を用いて、各素線の捻回値を１０回づつ測定し、そ
の平均値で捻回特性を評価した。 ○：２５回超、△：２５〜２０回、×：２０回未満(Twisting property) Using a torsion tester (manufactured by Shimadzu Corporation), the twisting value of each wire was measured 10 times, and the twisting property was evaluated by the average value. ○: more than 25 times, △: 25 to 20 times, ×: less than 20 times

【００２５】（腐食疲労特性）島津製作所製の腐食疲労
試験機を使用し、５％ＮａＣｌ水溶液中（３０℃）での
破断寿命（サイクル数）によって評価。 ◎：１０００kcycle超、 ○：１０００〜５００kcyc
le、△：５００〜１００kcycle、×：１００kcycle未満(Corrosion Fatigue Property) Using a corrosion fatigue tester manufactured by Shimadzu Corporation, evaluation was made by the breaking life (cycle number) in a 5% NaCl aqueous solution (30 ° C.). ◎: Over 1000 kcycles, ○: 1000-500 kcyc
le, △: 500 to 100 kcycle, ×: less than 100 kcycle

【００２６】（接着強度）各供試材を５％ＮａＣｌ水溶
液中（３０℃）に１週間浸漬したのち、ゴム片から試料
コードを引き抜いた時の剥離状態によって評価。 ○：引抜き部でゴムの凝集破壊発生、 ×：引抜き部でゴムの凝集破壊と試料コードとの界面破
壊との混合剥離(Adhesive Strength) Each test material was immersed in a 5% NaCl aqueous solution (30 ° C.) for 1 week and then evaluated by the peeling state when the sample cord was pulled out from the rubber piece. ◯: Cohesive failure of rubber occurred at the drawn portion, ×: Cohesive failure of rubber at the drawn portion and interfacial failure with the sample cord were mixed and separated

【００２７】結果は表２に示す通りであり、本発明の規
定要件を全て満足する実施例では、捻回特性、腐食疲労
特性、接着性の何れにおいても優れたものであるのに対
し、本発明で定めるいずれかの要件を欠く比較例では、
それら要求特性のいずれかが不充分であり、本発明の目
的に合致しない。The results are shown in Table 2. In the examples satisfying all the requirements of the present invention, the twisting property, the corrosion fatigue property, and the adhesive property were all excellent. In a comparative example lacking any of the requirements specified in the invention,
Any of these required properties is insufficient and does not meet the purpose of the present invention.

【００２８】[0028]

【表１】 [Table 1]

【００２９】[0029]

【表２】 [Table 2]

【００３０】実施例２ Ｃ：０．８２重量％、Ｓｉ：０．２４重量％、Ｍｎ：
０．５５重量％、Ｐ：０．００５重量％、Ｓ：０．００
６重量％、残部Ｆｅおよび不可避不純物からなる鋼材を
熱間圧延して線状に加工し、１次伸線加工、パテンティ
ング処理、２次伸線加工、再度のパテンティング処理、
真鍮めっきを順次施した後、最終工程で湿式伸線加工を
行ない、前記表３に示す如く長径（２ａ）、短径（２
ｂ）の異なる極細鋼線を作製した。各鋼線横断面の形状
特性を表３に示す。尚、各試料線材の横断面外形線は、
いずれも略［ｘ² ／ａ² ＋ｙ² ／ｂ² ＝１］となる様
に、また各素線はほぼ同じ引張強度（約３５０ｋｇ／ｍ
ｍ² ）を示す様に設定した。Example 2 C: 0.82% by weight, Si: 0.24% by weight, Mn:
0.55% by weight, P: 0.005% by weight, S: 0.00
Steel material consisting of 6% by weight, balance Fe and unavoidable impurities is hot-rolled into a linear shape, and is subjected to primary wire drawing, patenting treatment, secondary wire drawing, and patenting again.
After brass plating was applied in sequence, wet drawing was performed in the final step, and as shown in Table 3, the major axis (2a) and the minor axis (2a)
Ultrafine steel wires different in b) were produced. Table 3 shows the shape characteristics of each steel wire cross section. The cross-sectional outline of each sample wire is
In each case, the strand strength is approximately [x ² / a ² + y ² / b ² = 1], and the tensile strength of each wire is approximately the same (approximately 350 kg / m
m ² ).

【００３１】得られた各極細鋼線５本を撚り合わせ、上
記実施例１と同様にして捻回特性、腐食疲労特性および
接着強度を調べた。結果は表４に示す通りであり、本発
明の規定要件を満足する実施例の供試材は、捻回特性、
腐食疲労特性および接着強度のいずれにおいても優れた
性能を示しているのに対し、本発明の規定要件を欠く比
較例では、いずれかの性能が不充分である。Five ultrafine steel wires thus obtained were twisted together, and the twisting property, the corrosion fatigue property and the adhesive strength were examined in the same manner as in Example 1 above. The results are shown in Table 4, and the test materials of Examples satisfying the specified requirements of the present invention have twisting characteristics,
While excellent performance is exhibited in both corrosion fatigue properties and adhesive strength, any of the performances is insufficient in the comparative examples lacking the prescribed requirements of the present invention.

【００３２】[0032]

【表３】 [Table 3]

【００３３】[0033]

【表４】 [Table 4]

【００３４】また、前記表３に示した各供試材をタイヤ
用ゴム中に埋め込んだものを３０℃の５％ＮａＣｌ水溶
液中に１か月間浸漬し、各供試材の腐食減量を調べた。
尚腐食減量の測定に当たっては、供試材を埋め込んだゴ
ムの片面にクロスカットを入れ、クロスカット面以外の
面は保護塗料で被覆し、クロスカット面からの腐食によ
る重量減によって評価した（○：腐食減量１０ｇ／ｍ²
未満、△：腐食減量１０〜２０ｇ／ｍ² 、×：腐食減量
２０ｇ／ｍ² 超）。The test materials shown in Table 3 were buried in rubber for tires and immersed in a 5% NaCl aqueous solution at 30 ° C. for 1 month to examine the corrosion weight loss of each test material. .
In measuring the corrosion weight loss, a cross-cut was put on one side of the rubber in which the test material was embedded, the surface other than the cross-cut surface was covered with a protective paint, and the weight loss due to corrosion from the cross-cut surface was evaluated (○ : Corrosion weight loss 10 g / m ²
Less, △: Corrosion weight loss 10~20g / m ^2, ×: corrosion weight loss 20 g / m ² greater).

【００３５】結果は表５に示す通りであり、本発明の規
定要件を満たす実施例は、比較例に比べて腐食減量が格
段に少なく、優れた腐食疲労特性がゴム強化製品として
の耐久性向上に顕著に生かされることが分かる。The results are shown in Table 5. In Examples satisfying the requirements of the present invention, the corrosion weight loss was remarkably smaller than that in Comparative Examples, and the excellent corrosion fatigue properties were improved in durability as rubber reinforced products. It can be seen that it is remarkably utilized.

【００３６】[0036]

【表５】 [Table 5]

【００３７】[0037]

【発明の効果】本発明は以上の様に構成されており、極
細鋼線を横断面形状、長径／短径比、長径という形状面
から規定してガルバニック腐食を抑制することにより、
捻回特性を維持しつつ優れた耐食性と腐食疲労特性を備
えた極細鋼線を得ることができ、この極細鋼線は、その
優れた特性を生かして、タイヤ強化用あるいはベルト強
化用のスチールコードあるいはミニチュアロープの如
く、撚線加工して用いられる極細鋼線として有効に活用
することができる。EFFECT OF THE INVENTION The present invention is constituted as described above, and by controlling the galvanic corrosion by defining the ultrafine steel wire in terms of the cross-sectional shape, major axis / minor axis ratio, and major axis.
It is possible to obtain an ultrafine steel wire with excellent corrosion resistance and corrosion fatigue properties while maintaining the twisting characteristics.This ultrafine steel wire is a steel cord for tire reinforcement or belt reinforcement that makes use of its excellent characteristics. Alternatively, like a miniature rope, it can be effectively used as an extra fine steel wire used by being twisted.

【図面の簡単な説明】[Brief description of drawings]

【図１】真円状断面のワイヤと楕円状断面のワイヤの形
状特性を示す説明図である。FIG. 1 is an explanatory diagram showing shape characteristics of a wire having a perfect circular cross section and a wire having an elliptical cross section.

【図２】本発明で定める極細鋼線の横断面外形線を示す
説明図である。FIG. 2 is an explanatory view showing a contour line of a cross section of an ultrafine steel wire defined in the present invention.

【図３】本発明で定めるより好ましい極細鋼線の横断面
外形線を示す説明図である。FIG. 3 is an explanatory view showing a contour line of a cross section of a more preferable ultrafine steel wire defined in the present invention.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 茨木 信彦 兵庫県神戸市灘区灘浜東町２番地 株式会 社神戸製鋼所神戸製鉄所内 (72)発明者 落合 憲二 兵庫県神戸市灘区灘浜東町２番地 株式会 社神戸製鋼所神戸製鉄所内 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Nobuhiko Ibaraki, No. 2 Nadahama Higashi-cho, Nada-ku, Kobe-shi, Hyogo Stock Company Kobe Steel Works Kobe Steel Works (72) Kenji Ochiai No. 2 Nada-hama-Higashi-cho, Nada-ku, Kobe-shi, Hyogo Stock Company Kobe Steel Works Kobe Steel Works

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 めっき処理が施された極細鋼線におい
て、横断面の外形線が、下記式［１］で表わされる曲線
をＸ軸およびＹ軸で折り返して得られる閉曲線と、下記
式［２］で表わされる曲線をＸ軸およびＹ軸で折り返し
て得られる閉曲線との間の領域に属する任意の閉曲線で
表わされ、且つａ／ｂが１．０５〜５．０で、２ａが
１．０ｍｍ以下であることを特徴とする極細鋼線。 （ｘ¹⁰／ａ¹⁰）＋（ｙ¹⁰／ｂ¹⁰）＝１ ……［１］ （ｘ^1.2 ／ａ^1.2 ）＋（ｙ^1.2 ／ｂ^1.2 ）＝１……［２］ 但し、０≦ｘ≦ａかつ０≦ｙ≦ｂ ｘ＝０のときｙ＝ｂ，ｙ＝０のときｘ＝ａ1. In a plated ultrafine steel wire, the outline of the cross section is a closed curve obtained by folding the curve represented by the following formula [1] along the X axis and the Y axis, and the following formula [2] ] Is represented by an arbitrary closed curve belonging to a region between the closed curve obtained by folding back the curve represented by the X-axis and the Y-axis, and a / b is 1.05 to 5.0 and 2a is 1. An ultrafine steel wire characterized by being 0 mm or less. ^{(X 10 / a 10) +} (y 10 / b 10) = 1 ...... [1] (x 1.2 / a 1.2) + (y 1.2 / b 1.2) = 1 ...... [2] where, 0 ≦ x ≦ a and 0 ≦ y ≦ b y = b when x = 0, x = a when y = 0 【請求項２】 めっき処理が施された極細鋼線におい
て、横断面の外形線が、下記式［３］で表わされる曲線
をＸ軸およびＹ軸で折り返して得られる閉曲線と、下記
式［４］で表わされる曲線をＸ軸およびＹ軸で折り返し
て得られる閉曲線との間の領域に属する任意の閉曲線で
表わされ、且つａ／ｂが１．０５〜５．０で、２ａが
１．０ｍｍ以下であることを特徴とする極細鋼線。 （ｘ³ ／ａ³ ）＋（ｙ³ ／ｂ³ ）＝１ ……［３］ （ｘ^1.8 ／ａ^1.8 ）＋（ｙ^1.8 ／ｂ^1.8 ）＝１……［４］ 但し、０≦ｘ≦ａかつ０≦ｙ≦ｂ ｘ＝０のときｙ＝ｂ，ｙ＝０のときｘ＝ａ2. In a plated ultrafine steel wire, the outline of the cross section is a closed curve obtained by folding the curve represented by the following formula [3] along the X axis and the Y axis, and the following formula [4] ] Is represented by an arbitrary closed curve belonging to a region between the closed curve obtained by folding back the curve represented by the X-axis and the Y-axis, and a / b is 1.05 to 5.0 and 2a is 1. An ultrafine steel wire characterized by being 0 mm or less. (X ³ / a ³ ) + (y ³ / b ³ ) = 1 [3] (x ^1.8 / a ^1.8 ) + (y ^1.8 / b ^1.8 ) = 1 [4] where 0 ≦ x ≦ a and 0 ≦ y ≦ b y = b when x = 0, x = a when y = 0