JP3901751B2 - Steel cord for rubber reinforcement with excellent corrosion fatigue resistance - Google Patents
Steel cord for rubber reinforcement with excellent corrosion fatigue resistance Download PDFInfo
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- JP3901751B2 JP3901751B2 JP15263895A JP15263895A JP3901751B2 JP 3901751 B2 JP3901751 B2 JP 3901751B2 JP 15263895 A JP15263895 A JP 15263895A JP 15263895 A JP15263895 A JP 15263895A JP 3901751 B2 JP3901751 B2 JP 3901751B2
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- 229910000831 Steel Inorganic materials 0.000 title claims description 134
- 239000010959 steel Substances 0.000 title claims description 134
- 238000005260 corrosion Methods 0.000 title claims description 19
- 230000007797 corrosion Effects 0.000 title claims description 19
- 230000002787 reinforcement Effects 0.000 title description 4
- 230000003014 reinforcing effect Effects 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 238000004090 dissolution Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 description 14
- 230000008569 process Effects 0.000 description 9
- 238000005452 bending Methods 0.000 description 8
- 238000005491 wire drawing Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 210000003298 dental enamel Anatomy 0.000 description 2
- 239000012779 reinforcing material Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910000677 High-carbon steel Inorganic materials 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005562 fading Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- -1 nitrate ions Chemical class 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
Images
Classifications
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B1/00—Constructional features of ropes or cables
- D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
- D07B1/0606—Reinforcing cords for rubber or plastic articles
- D07B1/0646—Reinforcing cords for rubber or plastic articles comprising longitudinally preformed wires
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B1/00—Constructional features of ropes or cables
- D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
- D07B1/0606—Reinforcing cords for rubber or plastic articles
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2201/00—Ropes or cables
- D07B2201/20—Rope or cable components
- D07B2201/2015—Strands
- D07B2201/2019—Strands pressed to shape
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B5/00—Making ropes or cables from special materials or of particular form
- D07B5/005—Making ropes or cables from special materials or of particular form characterised by their outer shape or surface properties
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B5/00—Making ropes or cables from special materials or of particular form
- D07B5/007—Making ropes or cables from special materials or of particular form comprising postformed and thereby radially plastically deformed elements
Landscapes
- Ropes Or Cables (AREA)
- Tires In General (AREA)
- Reinforced Plastic Materials (AREA)
Description
【０００１】
【産業上の利用分野】
この発明は車両用空気入りタイヤとかコンベアベルト或いはホ−ス等のゴム物品の補強材として用いられるスチ−ルコ−ドに関わり、詳しくは耐腐食疲労性に優れた高強度のスチ−ルコ−ドに関わる。
【０００２】
【従来の技術】
ゴム物品の補強材に用いられるスチ−ルコ−ドは、ゴム物品の軽量化を図るために高強度化の要請が強い。しかしスチ−ルコ−ドを構成する鋼素線を高強度化すると、通常は耐疲労性の低下を来たし易い。
【０００３】
耐疲労性を改善するためにこれまでに幾つかの提案がなされている。例えば、特開平５−７１０８４号公報におけるスチ−ルワイヤでは、炭素量が０．６％以上の高炭素鋼線材のめっき後、伸線工程の最後にアプロ−チ角が８度以下の引抜ダイスを用いてワイヤ表面の残留応力をＸ線回折法で求められた軸方向における引っ張り側で４５Ｋｇ／ｍｍ2 以下とするものが提案されている。
【０００４】
また、特開昭５７−１４９５７８号公報の金属ワイヤは、外表面の残留応力を圧縮かつ均一に分散させることによって機械的疲労特性に優れたワイヤが得られるとされている。
更に、耐腐食疲労性に優れたスチ−ルコ−ドを得るために、原料となる線材に耐腐食性を与える元素を添加した合金鋼線材を用いたり、スチ−ルコ−ド内部にゴムを侵入させることによってスチ−ルフィラメントと水分との接触を抑制することが試みられている。
【０００５】
【発明が解決しようとする問題点】
前記した特開平５−７１０８４号公報で提案されている伸線時にスチ−ルワイヤ表面の残留引張り応力を低減する方法では、これらのスチ−ルワイヤを撚り合わせる時の塑性変形によって、スチ−ルコ−ドの撚りを解して得られた鋼素線の螺旋型付された螺旋内側に相対的に引張り側の残留応力が発生してしまい、耐腐食疲労性に対して効果が得られないという問題点がある。
【０００６】
また、特開昭５７−１４９５７８号公報で提案されている方法では、図５に示すように、主にスチ−ルコ−ドの円周外表面全域に残留圧縮応力を与えるように処理するために、鋼素線の螺旋形状の外側に主に残留圧縮応力が付与されることになり、ゴムが侵入しにくいスチ−ルコ−ド内部における耐腐食疲労性の向上に対しては予期するほどの効果が得られないという問題点がある。何故ならば、鋼素線に螺旋形に型付することで螺旋外側には耐腐食疲労性に対して充分な残留圧縮応力が発生しているためそれ以上の加工は不要だからである。
他方、耐食性を与えるために元素を添加する方法では、線材の価格が高くなったり伸線性が低下するという問題点がある。
【０００７】
更に、スチ−ルコ−ドが内部にゴムを侵入させて鋼素線と水分の接触を回避する耐食性の改善法はゴムの侵入が充分でないと効果が得られず、例えゴムの侵入が充分であったとしても接着が不充分であると鋼素線とゴムとの界面に空隙が生成して耐食性が低下する問題点がある。
【０００８】
【問題点を解決するための手段】
本発明は上記した欠点を解決したものであって、炭素含有量が０．７０重量％以上のゴム補強用スチ−ルコ−ド線材にて伸線加工を施して直径が０．１０〜０．４０ｍｍ、かつ、強度が３０００Ｎ／ｍｍ２ 以上の鋼素線となし、該鋼素線の複数本を撚り合わせてスチ−ルコ−ドとしたものであって、当該スチ−ルコ−ドを構成した際の鋼素線の性状として、このスチ−ルコ−ドの撚りを解して得た螺旋状の型付けを有する鋼素線の螺旋曲線率半径Ｒ０ と、同様にこのスチ−ルコ−ドの撚りを解して得た該鋼素線の螺旋内側部分における表面から内部に向かってこの鋼素線の直径の５％に相当する深さまでを溶解除去した時の螺旋の曲率半径Ｒ１ との比（Ｒ１ ／Ｒ０ ）×１００が１００未満であることを特徴とする耐食性に優れたゴム補強用スチ−ルコ−ドに係るものである。
【０００９】
そして、更に好ましくは、該鋼素線の螺旋内側部分における溶解除去を鋼素線の直径の１０％に相当する深さとしたゴム補強用スチ−ルコ−ドである。
【００１０】
【作用】
本発明は以上の構成を有するものであって、鋼素線の強度を高めると耐腐食疲労性が低下することは広く知られているが、この発明では鋼強度鋼素線の耐腐食疲労性を改善するためにはスチ−ルコ−ドを構成した際の鋼素線の性状として、このスチ−ルコ−ドの撚りを解して得た該鋼素線の螺旋内側部分における表面から内部に向かってこの鋼素線の直径の５％に相当する深さまでの螺旋内側残留引張り応力を小さくすれば良いことを見出したものである。
【００１１】
この発明にあって、ゴム補強用スチ−ルコ−ド線材の炭素含有量を０．７重量％以上と規定した理由は、ゴム物品の軽量化を図るために、素線の強度を３０００Ｎ／ｍｍ2 以上とする必要があるからである。
また、鋼素線の直径を０．１０ｍｍないし０．４０ｍｍの範囲に規定した理由は、０．１０ｍｍ未満では伸線工程での作業が低下し、０．４０ｍｍを越えると鋼素線の機械的耐疲労性が低下するからである。
【００１２】
さて、撚り合わせたスチ−ルコ−ドの撚りを解すと螺旋形状をした複数本の鋼素線となるが、これは真直な鋼素線をスチ−ルコ−ドとする撚線工程において塑性変形を鋼素線に与えるためである。伸線工程で鋼素線の表面残留引張り応力を低減しても撚線工程で鋼素線の螺旋内側に最大残留引張り応力が発生してしまい、ゴムが侵入し難いコ−ド内部、即ち、鋼素線の螺旋内側が腐食環境下にさらされて腐食疲労しやすくなる。
【００１３】
この発明の要旨は前記したようにスチ−ルコ−ドを構成する鋼素線の撚線工程による鋼素線の螺旋内側における残留引張り応力を低減することにあり、このことから、特開平５−７１０８４号公報に提案されている伸線工程における鋼素線にこの残留引張り応力を低減する考えも併用できる。
【００１４】
ゴム補強用スチ−ルコ−ドにおいては、ゴム物品、例えばタイヤが自動車に装着されて走行する際に繰り返し曲げをうけて、スチ−ルコ−ドを構成する鋼素線同士が摩擦摩耗するフレテイングが発生し、更に腐食疲労しやすくなる。このために、鋼素線の表面から素線直径の５％深さまでの範囲で残留引張り応力を小さくするもので、好ましくは、鋼素線の表面から素線直径の１０％深さまでの範囲で残留引張り応力を小さくするのがよい。
【００１５】
さて、スチ−ルコ−ドの撚りを解して得た鋼素線の螺旋内側における長手方向の引張り残留応力を小さくするには、鋼素線の弾性限界応力をσ1 として、螺旋状に型付された鋼素線の直径方向における断面内全てに圧縮塑性が生成しないような応力をσ2 とし、螺旋内側の最大残留引張り応力をσ3 とすると、σ3 ＋σ2 −σ1 ＞０の関係を満たすように処理する。この処理によってσ3 ＋σ2 −σ1 ＞０の範囲にある鋼素線の部分は塑性変形が生成することになる。これを図１によって更に詳細に説明する。
【００１６】
図１の（ア）は、説明を判りやすくするために伸線に伴う残留応力は無視して、撚線に伴う残留応力を模式的に示したもので、撚りを解した鋼素線は螺旋形に型付されており、螺旋形の内側表層部で最大の残留引張り応力であることを示している。図１の（イ）は、鋼素線に直径方向の断面内全てに圧縮塑性が生成しないような応力を加えた時の応力分布図であり、鋼素線表面からＬ1 の深さまでがσ3 ＋σ2 −σ1 ＞０を満足している範囲である。また、図１の（ウ）は、応力σ2 を除去した時の残留応力を示す図である。
【００１７】
【実施例】
炭素含有量が０．８重量％である炭素鋼からなる直径０．２３ｍｍで強度が３８００Ｎ／ｍｍ2 鋼素線をピッチ６ｍｍの螺旋状に型付された３本の素線をコアとし、ピッチ１２ｍｍの螺旋型付された９本の鋼素線をコアの周囲に巻き付け、更にその外側に１本の鋼素線を巻き付けた（３＋９＋１）構造のスチ−ルコ−ドを撚線機により製造した。また、スチ−ルコ−ドを構成している螺旋状に型付された鋼素線における螺旋内側の残留応力分布を計算によって求めた。
次いでσ3 ＋σ2 −σ1 ＞０の関係を満たすようスチ−ルコ−ドを図２に示す装置で処理することにより、鋼素線の螺旋内側表層部の最大残留応力を所要の深さまで低減した。
【００１８】
図２のＡ１、Ａ２はスチ−ルコ−ドに張力を与えるための張力負荷装置であり、自由に張力負荷が設定できる機構となっている。Ｂはスチ−ルコ−ドに曲げを与える曲げ装置で複数個のロ−ラ−を千鳥状に配置したもので、スチ−ルコ−ドの曲げ量を自由に変化できるようにしてある。Ｃはスチ−ルコ−ドの巻取り装置である。Ａ１、Ａ２間のスチ−ルコ−ドの張力はＡ１によって自由に調整できる仕組みとなっており、Ｂはスチ−ルコ−ドに張力が加わっていない時には、塑性変形が起こらないようなロ−ル径と噛み深さに調整して弾性域においてのみ曲げ加工が加わるようにする。この調整は前述のσ１、σ２、σ３の関係、すなわちσ３＋σ２−σ１＞０により所望する深さまで残留応力が低減できるようにスチ−ルコ−ドに対して１０００Ｎ／ｍｍ2 、１３００Ｎ／ｍｍ2 、１５００Ｎ／ｍｍ2 の張力を加えた。
【００１９】
このようにして製造したスチ−ルコ−ドを構成する鋼素線の性状としてこのスチ−ルコ−ドの撚りを解して螺旋状の型付けを有する鋼素線に分解し、これら鋼素線の内シ−スを構成する鋼素線について１００ｍｍ長さに切断して鋼素線の長手方向、かつ、半円周にエナメルを塗布した後、硝酸の５０％水溶液に浸漬し、エナメルを塗布していない半円周側を所定の厚みにまで溶解し、その時の連続的な素線の動きを測定した。測定は鋼素線の螺旋内側が溶解する時の曲率半径の動きと、鋼素線１００ｍｍ全体についての動きの両者について行った。前者における測定は図３に示す通りであり、図中、Ｒ０ は螺旋内側の除去前の螺旋曲率半径（ｍｍ）であり、Ｒ１ は螺旋内側除去後の螺旋曲率半径（ｍｍ）である。また、後者における測定は図４に示す通りであり、Ｐ側に移動した場合を−、Ｑ側に移動の場合を＋とする。
【００２０】
耐腐食疲労性の評価は、１００ｍｍ長さに切断したスチ−ルコ−ドも少量の硝酸イオン及び硫酸イオンを含む中性の水溶液に浸し、毎分１０００回転の速度で３００Ｎ／ｍｍ2 の繰り返し曲げ応力を与えて鋼素線が破断に至るまでの回転数を記録した。表１では比較例１の破断に至るまでの回転数を１００として指数表示しており数字が大きいほど耐腐食疲労性に優れていることを表している。
【００２１】
尚、比較例１のスチ−ルコ−ドは、伸線後、繰り返し曲げ加工によって鋼素線表面の残留引張り応力を低減してから撚線したものであり、撚線によって残留引張り応力の低減効果が薄れていることを示している。比較例２は、提案技術のように、スチ−ルコ−ドとした後に残留引張り応力をＡ１、Ａ２による張力を５００Ｎ／ｍｍ２ とし、ロ−ラ−による曲げ加工の調整によってスチ−ルコ−ドの円周全面に残留圧縮応力を与えるような処理を行ったものであるが、素線１００ｍｍ全体の移動は残留応力が圧縮の動作をするが、鋼素線に型付された螺旋内側の残留引張り応力は低減されていないことを示す。
【００２２】
表１に比較例及び発明例の結果を示す。
コアについての螺旋内側溶解時の螺旋曲率半径の変化、鋼素線１００ｍｍ長さ全体の移動はシ−スと同じ結果を得た。
【００２３】
【表１】
【発明の効果】
ゴム補強用スチ−ルコ−ドを構成する鋼素線の螺旋内側部の残留引張り応力を低減したので、スチ−ルコ−ドの耐腐食疲労性が向上し、腐食環境下で用いられるゴム物品の耐久性を大幅に改善した有用な発明であり、更にこの発明に適用されるスチ−ルコ−ドは高強度であることからゴム物品の軽量化が図れると共に耐久性も改善できるという極めて有用な発明である。
【図面の簡単な説明】
【図１】 図１はスチ−ルコ−ドを構成する鋼素線の直径方向横断面における応力分布を示す模式図である。
【図２】 図２はこの発明のスチ−ルコ−ドを製造するための部分図である。
【図３】 図３は螺旋型付が施された鋼素線の螺旋内側での曲率半径の変化を示す図である。
【図４】 図４はスチ−ルコ−ド１００ｍｍの先端の移動量を示す図である。
【図５】 図５はスチ−ルコ−ドを繰り返し曲げ主体の調整によって、残留応力が低減する部分を示す図である。
【符号の説明】
Ａ１、Ａ２‥‥スチ−ルコ−ドに張力を与える張力負荷装置、
Ｂ‥‥スチ−ルコ−ドに曲げを与える曲げ装置、
Ｃ‥‥Ｃはスチ−ルコ−ドの巻取り装置、
Ｒ０ ‥‥螺旋内側表面除去前の螺旋曲率半径、
Ｒ１ ‥‥螺旋内側表面除去後の螺旋曲率半径、
Ｓ‥‥円周外表面（螺旋外側）。[0001]
[Industrial application fields]
The present invention relates to a steel cord used as a reinforcing material for rubber articles such as a pneumatic tire for a vehicle, a conveyor belt or a hose, and more specifically, a high strength steel cord excellent in corrosion fatigue resistance. Involved.
[0002]
[Prior art]
Steel cords used as a reinforcing material for rubber articles are strongly required to have high strength in order to reduce the weight of the rubber articles. However, when the strength of the steel wire constituting the steel cord is increased, the fatigue resistance usually tends to be lowered.
[0003]
Several proposals have been made to improve fatigue resistance. For example, in the steel wire disclosed in JP-A-5-71084, after a high carbon steel wire having a carbon content of 0.6% or more is plated, a drawing die having an approach angle of 8 degrees or less is applied at the end of the wire drawing process. It has been proposed that the residual stress on the wire surface be 45 Kg / mm 2 or less on the tensile side in the axial direction determined by the X-ray diffraction method.
[0004]
In addition, the metal wire disclosed in Japanese Patent Application Laid-Open No. 57-149578 is said to provide a wire having excellent mechanical fatigue characteristics by compressing and uniformly dispersing the residual stress on the outer surface.
Furthermore, in order to obtain a steel cord having excellent corrosion fatigue resistance, an alloy steel wire added with an element that gives corrosion resistance to the raw wire material is used, or rubber is penetrated into the steel cord. It has been attempted to suppress contact between the steel filament and moisture.
[0005]
[Problems to be solved by the invention]
In the method of reducing the residual tensile stress on the surface of the steel wire at the time of wire drawing proposed in the above-mentioned Japanese Patent Application Laid-Open No. 5-71084, the steel cord is deformed by plastic deformation when these steel wires are twisted together. There is a problem that the residual stress on the tension side is relatively generated inside the spiral of the steel wire obtained by untwisting the steel wire, and the effect on corrosion fatigue resistance cannot be obtained. There is.
[0006]
Further, in the method proposed in Japanese Patent Laid-Open No. 57-149578, as shown in FIG. 5, in order to apply a residual compressive stress mainly to the entire outer circumferential surface of the steel cord. , The residual compressive stress is mainly applied to the outside of the spiral shape of the steel wire, and the effect as expected for the improvement of the corrosion fatigue resistance inside the steel cord where the rubber does not easily penetrate. There is a problem that cannot be obtained. This is because by forming a steel wire in a spiral shape, a residual compressive stress sufficient for corrosion fatigue resistance is generated on the outer side of the spiral, so that further processing is unnecessary.
On the other hand, the method of adding an element in order to give corrosion resistance has a problem that the price of the wire is increased or the wire drawing property is lowered.
[0007]
Furthermore, the method of improving the corrosion resistance in which the steel cord penetrates the rubber inside to avoid the contact between the steel wire and moisture cannot be effective unless the rubber penetrates sufficiently, for example, the rubber penetrates sufficiently. Even if it exists, there is a problem that if the adhesion is insufficient, voids are generated at the interface between the steel wire and the rubber, and the corrosion resistance is lowered.
[0008]
[Means for solving problems]
The present invention solves the above-mentioned drawbacks, and is drawn with a steel cord wire for reinforcing rubber having a carbon content of 0.70% by weight or more, and has a diameter of 0.10 to 0.00. A steel wire having a strength of 40 mm and a strength of 3000 N / mm 2 or more is formed by twisting a plurality of steel wires into a steel cord, and the steel cord is configured. As the properties of the steel wire at the time, the spiral curve radius R 0 of the steel wire having a spiral type obtained by untwisting the steel cord, and the steel cord The radius of curvature R 1 of the helix when the steel strand obtained by untwisting is melted and removed from the surface to the depth corresponding to 5% of the diameter of the steel strand from the surface to the inside. the ratio rubber reinforcement (R 1 / R 0) × 100 is excellent in corrosion resistance and less than 100 Steel - Turkey - are those related to de.
[0009]
More preferably, it is a steel cord for reinforcing rubber in which the removal of dissolution in the inner spiral portion of the steel wire is made to a depth corresponding to 10% of the diameter of the steel wire.
[0010]
[Action]
The present invention has the above-mentioned configuration, and it is widely known that the corrosion fatigue resistance decreases when the strength of the steel strand is increased. However, in this invention, the corrosion fatigue resistance of the steel strength steel strand is reduced. In order to improve the steel cord, the properties of the steel wire at the time of constituting the steel cord, from the surface in the spiral inner portion of the steel wire obtained by untwisting this steel cord from the surface to the inside On the other hand, it has been found that the residual tensile stress inside the spiral up to a depth corresponding to 5% of the diameter of the steel wire may be reduced.
[0011]
In the present invention, the reason why the carbon content of the steel cord wire for rubber reinforcement is defined as 0.7% by weight or more is that the strength of the wire is 3000 N / mm in order to reduce the weight of the rubber article. It is because it is necessary to make it 2 or more.
Also, the reason why the diameter of the steel wire is defined in the range of 0.10 mm to 0.40 mm is that if it is less than 0.10 mm, the work in the wire drawing process is reduced, and if it exceeds 0.40 mm, the mechanical strength of the steel wire is reduced. This is because fatigue resistance decreases.
[0012]
Now, when the twisted steel cord is untwisted, it becomes a plurality of helically shaped steel strands, which are plastically deformed in the stranding process in which straight steel strands are steel cords. This is to give to the steel strand. Even if the surface residual tensile stress of the steel strand is reduced in the wire drawing process, the maximum residual tensile stress is generated inside the spiral of the steel strand in the twisting process, and the rubber is difficult to penetrate, i.e. The spiral inside of the steel wire is exposed to a corrosive environment, and corrosion fatigue tends to occur.
[0013]
The gist of the present invention is to reduce the residual tensile stress inside the helix of the steel wire by the twisting process of the steel wire constituting the steel cord as described above. The idea of reducing this residual tensile stress can be used in combination with the steel wire in the wire drawing process proposed in Japanese Patent No. 71084.
[0014]
In the steel cord for reinforcing rubber, there is a fretting in which a rubber article, for example, a tire, is repeatedly bent when traveling while being mounted on an automobile, and the steel wires constituting the steel cord are frictionally worn. Occurs and is more susceptible to corrosion fatigue. For this purpose, the residual tensile stress is reduced in the range from the surface of the steel strand to 5% depth of the strand diameter, preferably in the range from the surface of the steel strand to 10% depth of the strand diameter. It is better to reduce the residual tensile stress.
[0015]
Now, in order to reduce the tensile residual stress in the longitudinal direction inside the helix of the steel wire obtained by untwisting the steel cord, the elastic limit stress of the steel wire is set as σ 1 and the shape is helically formed. Σ 3 + σ 2 −σ 1 > 0, where σ 2 is the stress that does not generate compressive plasticity in the entire cross section in the diameter direction of the attached steel wire, and σ 3 is the maximum residual tensile stress inside the helix Process to satisfy the relationship. By this treatment, plastic deformation is generated in the portion of the steel wire in the range of σ 3 + σ 2 −σ 1 > 0. This will be described in more detail with reference to FIG.
[0016]
In Fig. 1 (a), the residual stress accompanying wire drawing is neglected to make the explanation easy to understand, and the residual stress accompanying twisted wire is schematically shown. It has been shaped into a shape, indicating the maximum residual tensile stress at the spiral inner surface. FIG. 1 (a) is a stress distribution diagram when stress that does not generate compression plasticity in the entire cross section in the diametrical direction is applied to the steel wire, and the distance from the surface of the steel wire to the depth of L 1 is σ. 3 + σ 2 −σ 1 > 0. FIG. 1C is a diagram showing the residual stress when the stress σ 2 is removed.
[0017]
【Example】
The three strands carbon content intensity diameter 0.23mm made of carbon steel is 0.8 wt% has been typed to 3800N / mm 2 steel wires helically pitch 6mm and the core, the pitch A steel cord having a (3 + 9 + 1) structure in which nine steel strands having a 12 mm spiral shape were wound around the core and one steel strand was wound outside the core was manufactured by a twisting machine. . Moreover, the residual stress distribution inside the helix in the steel element wire formed in a spiral shape constituting the steel cord was obtained by calculation.
Next, the steel cord is processed with the apparatus shown in FIG. 2 so as to satisfy the relationship of σ 3 + σ 2 −σ 1 > 0, thereby reducing the maximum residual stress of the inner surface layer portion of the steel wire to the required depth. did.
[0018]
A1 and A2 in FIG. 2 are tension load devices for applying tension to the steel cord, and are mechanisms that can freely set the tension load. B is a bending device which bends the steel cord, and a plurality of rollers are arranged in a staggered manner, and the bending amount of the steel cord can be freely changed. C is a steel cord winding device. The steel cord tension between A1 and A2 can be freely adjusted by A1, and B is a roll that does not cause plastic deformation when no tension is applied to the steel cord. The bending process is applied only in the elastic region by adjusting the diameter and the biting depth. This adjustment is performed at 1000 N / mm 2 , 1300 N / mm 2 , 1500 N with respect to the steel code so that the residual stress can be reduced to a desired depth by the above-mentioned relationship of σ1, σ2, σ3, that is, σ3 + σ2-σ1> 0. A tension of / mm 2 was applied.
[0019]
As a property of the steel wire constituting the steel cord thus manufactured, the steel cord is untwisted and disassembled into a steel wire having a spiral type. The steel strand constituting the inner sheath is cut to a length of 100 mm and enamel is applied in the longitudinal direction of the steel strand and in the semicircular direction, and then immersed in a 50% aqueous solution of nitric acid, and the enamel is applied. The semicircular side which was not melted was melted to a predetermined thickness, and the movement of the continuous wire at that time was measured. The measurement was performed for both the movement of the radius of curvature when the spiral inside of the steel strand melts and the movement of the entire steel strand 100 mm. The measurement in the former is as shown in FIG. 3, in which R 0 is the spiral radius of curvature (mm) before removal of the inside of the spiral, and R 1 is the spiral radius of curvature (mm) after removal of the inside of the spiral. Further, the measurement in the latter is as shown in FIG. 4, and the case of moving to the P side is-, and the case of moving to the Q side is +.
[0020]
The corrosion fatigue resistance was evaluated by immersing a steel cord cut to a length of 100 mm in a neutral aqueous solution containing a small amount of nitrate ions and sulfate ions and repeatedly bending 300 N / mm 2 at a speed of 1000 revolutions per minute. The number of revolutions until the steel wire was broken by applying stress was recorded. In Table 1, the number of rotations up to the break in Comparative Example 1 is shown as an index, and the larger the number, the better the corrosion fatigue resistance.
[0021]
The steel cord of Comparative Example 1 is a stranded wire after wire drawing after reducing the residual tensile stress on the surface of the steel wire by repeated bending, and the effect of reducing the residual tensile stress by the stranded wire. Indicates that is fading. Comparative Example 2, as proposed technology, steel - Turkey - and 500 N / mm 2 tension due to the residual tensile stress A1, A2 after the de, Russia - la - due to bending steel by adjusting the working - Turkey - de Although the residual stress is applied to the entire circumference of the steel wire, the movement of the entire strand 100 mm causes the residual stress to be compressed, but the residual inside the helix molded on the steel strand. It shows that the tensile stress is not reduced.
[0022]
Table 1 shows the results of Comparative Examples and Invention Examples.
Changes in the radius of curvature of the spiral during melting of the inner side of the core and the movement of the entire length of the steel strand 100 mm were the same as in the case.
[0023]
[Table 1]
【The invention's effect】
Since the residual tensile stress at the inner spiral portion of the steel wire constituting the steel cord for rubber reinforcement is reduced, the corrosion resistance of the steel cord is improved and the rubber article used in the corrosive environment is improved. It is a useful invention that has greatly improved durability, and the steel cord applied to this invention has high strength, so that the weight of the rubber article can be reduced and the durability can be improved. It is.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a stress distribution in a diametrical cross section of a steel wire constituting a steel cord.
FIG. 2 is a partial view for producing a steel code of the present invention.
FIG. 3 is a diagram showing a change in the radius of curvature inside the helix of a steel wire to which a spiral die is attached.
FIG. 4 is a diagram showing the amount of movement of the tip of a steel cord of 100 mm.
FIG. 5 is a diagram showing a portion in which residual stress is reduced by repeatedly adjusting a steel cord and repeatedly bending the main body.
[Explanation of symbols]
A1, A2 ... Tension load device that applies tension to the steel cord,
B ... Bending device that bends the steel cord,
C ... C is a steel cord winding device,
R 0 ... the radius of curvature of the spiral before removing the inner surface of the spiral,
R 1 ... the radius of curvature of the spiral after removal of the inner surface of the spiral,
S ... Circumferential outer surface (spiral outside).
Claims (2)
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15263895A JP3901751B2 (en) | 1995-05-26 | 1995-05-26 | Steel cord for rubber reinforcement with excellent corrosion fatigue resistance |
| US08/652,082 US5806296A (en) | 1995-05-26 | 1996-05-23 | Corrosion resistant spiral steel filament and steel cord made therefrom |
| ES96303709T ES2202415T3 (en) | 1995-05-26 | 1996-05-24 | STEEL THREADS AND PNEUMATIC COVER FOR USE. |
| DE69629076T DE69629076T2 (en) | 1995-05-26 | 1996-05-24 | Steel cable and thus reinforced pneumatic tire |
| EP96303709A EP0744490B1 (en) | 1995-05-26 | 1996-05-24 | Steel cord and pneumatic tire using the same |
| KR1019960017923A KR100431373B1 (en) | 1995-05-26 | 1996-05-25 | Steel cord and pneumatic tire using the same |
| US08/769,572 US5873962A (en) | 1995-05-26 | 1996-12-19 | Tire having corrosion resistant steel cord |
| US08/944,223 US5822973A (en) | 1995-05-26 | 1997-10-06 | Corrosion resistant steel filament |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15263895A JP3901751B2 (en) | 1995-05-26 | 1995-05-26 | Steel cord for rubber reinforcement with excellent corrosion fatigue resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08325965A JPH08325965A (en) | 1996-12-10 |
| JP3901751B2 true JP3901751B2 (en) | 2007-04-04 |
Family
ID=15544781
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15263895A Expired - Fee Related JP3901751B2 (en) | 1995-05-26 | 1995-05-26 | Steel cord for rubber reinforcement with excellent corrosion fatigue resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3901751B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100493673B1 (en) * | 1999-01-08 | 2005-06-03 | 한국타이어 주식회사 | A radial tire applied a steel cord in the carcass |
| KR20000050439A (en) * | 1999-01-08 | 2000-08-05 | 조충환 | A radial tire applied a steel cord in the carcass for the riding car and the light truck |
-
1995
- 1995-05-26 JP JP15263895A patent/JP3901751B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08325965A (en) | 1996-12-10 |
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