JPH0417596Y2

JPH0417596Y2 -

Info

Publication number: JPH0417596Y2
Application number: JP1988082173U
Authority: JP
Priority date: 1988-06-21
Filing date: 1988-06-21
Publication date: 1992-04-20
Also published as: JPH023496U

Description

[Detailed explanation of the idea]

〔産業上の利用分野〕本考案は自動車用タイヤ、コンベアベルト等の
ゴム補強材として用いられるスチールコードの改
良に関するものである。〔従来の技術〕近年、自動車用タイヤでは、自動車の乗り心地
性を改善するためのタイヤの弾力性、タイヤの長
寿命化および燃費を改善するためのタイヤの軽量
化が特に求められている。中でも長寿命化の要因としては、スチールコー
ドの耐カツト性と腐食があげられる。タイヤが小石、縁石等に乗り上げた時に生じる
スチールコードの切断を防ぐ耐カツト性の向上に
対しては、タイヤのベルト部に高い伸度を有する
スチールコード、いわゆるHigh Elongation
Cordを使用することが考えられ、現在ではトラ
ツク、バス用タイヤのベルト部へは３×７，４×
３，４×４等の撚り構成で、撚りピツチを小さく
した多重撚りのスチールコードがより高い伸度を
得るスチールコードとして用いられている。また、通常、乗用車用タイヤには１×４，１×
５等の単層撚りのスチールコードが用いられてい
る。〔考案が解決しようとする課題〕上記多重撚りのスチールコードは撚りピツチが
小さく、しかも多重撚りであるため生産性が悪
く、製造コストが高くなるという問題点があり、
また単層撚りのスチールコードでは破断迄の伸度
が2.5〜3.8％と低く、High Elongation Cordと
しては伸びの効果が期待できないという問題点が
ある。また、一方では自動車が路面を走行中にタイヤ
が外傷を受けたとき、その傷から侵入した水分が
スチールコードの中央部の空隙に入り、この空隙
内をスチールコードの長手方向に伝播して腐食を
発生させ、スチールコードの疲労性の低下とゴム
の接着性の低下を伴い、タイヤのセパレーシヨン
現象を誘発するという問題点がある。上記タイヤの外傷によるスチールコードの腐食
や、セパレーシヨン現象の防止のために最近では
オープンコードと呼ばれる素線間に隙間を設ける
よう緩く撚つたスチールコードが使用されている
が、これをより緩く撚つた状態のオープンコード
で伸びを５％以上と大きくすることも考えられる
が、素線間の自由空間が大きくなりすぎ、タイヤ
成型時のゴム加硫時にスチールコードの長手方向
にしごきの形で外力が負荷された場合、素線がコ
ード中心軸を軸芯にして回転し、それに伴つて素
線間の隙間が減少し、ゴムがスチールコードの素
線内部迄充分に侵入せず、スチールコードの腐食
やセパレーシヨン現象を誘発するという問題点を
有し、実用には至つていない。〔課題を解決するための手段〕本考案は上記問題点を除去するためになされた
ものであり、３本乃至６本の素線を同一方向、同
一ピツチで撚り合わせた単層撚りのオープン撚り
スチールコードにおいて、素線径ｄと撚りピツチ
Ｐの比が10≦Ｐ／ｄ≦28で、破断迄のコード伸度
が５％以上であり、かつコードの外接円がコード
長手方向にほぼ一定の略楕円形をなし、その短径
D₁と長径D₂の比がD₂／D₁≧1.1で、しかもコード
のいずれの横断面においても、素線間に少なくと
も１ケ所、２／100mm以上の隙間が存在し、しか
もHigh Elongation Cordである３×７，４×４
等のスチールコードと、その伸び、強力が略同等
で、しかも安価に製造できるスチールコードを提
供するものである。〔実施例１〕線径が5.5mmψのピアノ線材を熱処理と伸線を
繰り返し、途中で真鍮メツキを施して素線径ｄが
0.38mmψのスチールコード用の素線１を形成す
る。上記素線１の５本を同一方向で、撚りピツチＰ
が6.5の同一撚りピツチＰで撚り合わせ、撚りピ
ツチＰと素線径ｄの比がＰ／ｄ＝17.1で１×５の
撚り構成を有するオープンコードを形成し、上記
オープンコードをローラーにかけて第１図に示す
ように、破断迄のコード伸度が５％以上で、コー
ドの外接円がコード長手方向にほぼ一定の略楕円
形とし、上記楕円形の外接円の短径D₁と長径D₂
の比がD₂／D₁≧1.2であり、しかもコードのいず
れの横断面においても、素線間に少なくとも１ケ
所、３／100mmの隙間を有したスチールコード２
を構成した。〔実施例２〕実施例１と同様にして素線径ｄが0.30mmψのス
チールコード用の素線３を形成し、上記素線３を
４本、同一方向でかつ撚りピツチＰが6.0の同一
撚りピツチで撚り合わせ、撚りピツチＰと素線径
ｄの比がＰ／ｄ＝20で１×４の撚り構成を有する
オープンコードを形成した。上記オープンコードをローラーにかけて第２図
に示すように、破断迄のコード伸度が５％以上
で、コードの外接円がコード長手方向にほぼ一定
の略楕円形とし、上記楕円形の外接円の短径D₁
と長径D₂の比がD₂／D₁≧1.3であり、しかもコー
ドのいずれの横断面においても、素線間に少なく
とも１ケ所、４／100mmの隙間を有したスチール
コード４を構成した。なお、上記実施例において、コードの断面にお
ける少なくとも１ケ所の隙間を３／100mmあるい
は４／100mmとしたが、隙間Ｃが２／100mm以上を
有するように構成することが可能である。また、１×3A，１×4B，１×5C，１×6Dの
単層撚りにおける撚りピツチＰと素線径ｄの比と
コードの伸びとの関係をみると第３図に示すとお
りである。この図からわかるように、伸び率が５％を確保
するためにはＰ／ｄは28が最大となり、10以下に
すると素線に無理な塑性変形が加わりコード強力
が極端に低下するとともに製造コストが高くな
る。上記のように構成された本考案のスチールコー
ドのゴム侵入率を次の加硫条件でゴム被覆して調
べたところ第４図に示すとおりであつた。 [Industrial Application Field] The present invention relates to the improvement of steel cords used as rubber reinforcing materials for automobile tires, conveyor belts, etc. [Prior Art] In recent years, in automobile tires, there has been a particular demand for tire elasticity to improve the riding comfort of automobiles, tire life extension, and tire weight reduction to improve fuel efficiency. Among these factors, the cut resistance and corrosion resistance of the steel cord are factors that contribute to longer life. In order to improve the cut resistance of the steel cord, which prevents the steel cord from being cut when the tire runs over a pebble, curbstone, etc., a steel cord with high elongation, so-called High Elongation, is used in the belt section of the tire.
Cord was considered to be used, and currently 3x7, 4x
Multi-twist steel cords with a twist configuration of 3, 4 x 4, etc. with a small twist pitch are used as steel cords that can obtain higher elongation. In addition, passenger car tires usually have 1×4, 1×
Grade 5 single-layer twisted steel cord is used. [Problems to be solved by the invention] The above-mentioned multi-twisted steel cord has a small twist pitch, and since it is multi-twisted, productivity is low and manufacturing costs are high.
In addition, single-layer twisted steel cord has a low elongation of 2.5 to 3.8% before breaking, so there is a problem in that high elongation cord cannot be expected to have an elongation effect. On the other hand, when a tire is damaged while a car is driving on the road, moisture that has entered through the damage enters the gap in the center of the steel cord, propagates in the longitudinal direction of the steel cord through this gap, and corrodes the tire. This is accompanied by a decrease in the fatigue strength of the steel cord and a decrease in the adhesion of the rubber, leading to a problem of tire separation. In order to prevent corrosion of the steel cord due to tire trauma and the separation phenomenon mentioned above, recently a steel cord called an open cord is used, which is loosely twisted so as to leave gaps between the strands. It is possible to increase the elongation to 5% or more using an open cord in the ivy state, but the free space between the strands would become too large, and an external force in the longitudinal direction of the steel cord would be applied during rubber vulcanization during tire molding. When a load is applied, the strands rotate around the center axis of the cord, and the gap between the strands decreases, preventing the rubber from penetrating sufficiently into the strands of the steel cord, causing damage to the steel cord. This has the problem of inducing corrosion and separation phenomena, and has not been put into practical use. [Means for Solving the Problems] The present invention was made to eliminate the above problems, and is a single-layer open strand in which three to six strands are twisted in the same direction and at the same pitch. For steel cords, the ratio of wire diameter d to twist pitch P is 10≦P/d≦28, the cord elongation until breakage is 5% or more, and the circumscribed circle of the cord is approximately constant in the longitudinal direction of the cord. Almost elliptical, its short axis
The ratio of D ₁ to major axis D ₂ is D ₂ /D ₁ ≧1.1, and there is a gap of 2/100 mm or more between the strands at least in one place in any cross section of the cord, and the cord is a High Elongation Cord. 3×7, 4×4
The purpose of the present invention is to provide a steel cord that has approximately the same elongation and strength as those of the above steel cord, and can be manufactured at a low cost. [Example 1] Piano wire with a wire diameter of 5.5 mmψ was repeatedly heat treated and wire drawn, and brass plating was applied in the middle to reduce the wire diameter d.
A strand 1 for a steel cord of 0.38 mmψ is formed. Twist the five strands of the above strands 1 in the same direction, P
is twisted at the same twist pitch P of 6.5 to form an open cord having a 1×5 twist configuration with a ratio of twist pitch P to strand diameter d of P/d=17.1, and the open cord is passed through a roller to form the first As shown in the figure, the cord elongation before breakage is 5% or more, the circumscribed circle of the cord is approximately constant in the longitudinal direction of the cord, and the circumscribed circle is approximately elliptical, and the minor axis D ₁ and major axis D ₂ of the circumscribed circle of the ellipse are
A steel cord 2 having a ratio of D ₂ /D ₁ ≧1.2 and having at least one gap of 3/100 mm between the strands in any cross section of the cord.
was constructed. [Example 2] A strand 3 for a steel cord with a strand diameter d of 0.30 mmψ was formed in the same manner as in Embodiment 1, and four of the above strands 3 were arranged in the same direction and with a twist pitch P of 6.0. The wires were twisted together at a twist pitch to form an open cord having a 1×4 twist configuration with a ratio of the twist pitch P to the wire diameter d of P/d=20. As shown in Figure 2, the open cord is rolled to form a substantially elliptical shape with a cord elongation of 5% or more before breakage and a circumscribed circle of the cord that is approximately constant in the longitudinal direction of the cord, as shown in Figure 2. Short diameter D ₁
The steel cord 4 was constructed such that the ratio of D ₂ to major axis D 2 was D ₂ /D ₁ ≧1.3, and also had at least one gap of 4/100 mm between the strands in any cross section of the cord. In the above embodiment, at least one gap in the cross section of the cord is 3/100 mm or 4/100 mm, but it is possible to configure the gap C to be 2/100 mm or more. Furthermore, the relationship between the ratio of the twist pitch P to the wire diameter d and the elongation of the cord in single-layer twists of 1×3A, 1×4B, 1×5C, and 1×6D is as shown in Figure 3. . As can be seen from this figure, in order to ensure an elongation rate of 5%, the maximum P/d is 28, and if it is less than 10, unreasonable plastic deformation will occur on the strands, resulting in an extremely low cord strength and manufacturing costs. becomes higher. The rubber penetration rate of the steel cord of the present invention constructed as described above was investigated by coating it with rubber under the following vulcanization conditions, and the results were as shown in FIG.

[Effect of idea]

本考案のスチールコードは上記構成であるた
め、単層撚りで多重撚りと同様の５％以上の高伸
度の伸びが得られ、タイヤの摩耗性能及び耐カツ
ト性能に優れる。また、コード外接円が楕円形状で、しかもコー
ド長手方向にほぼ一定であるため、初期低荷重時
の伸びを抑えることができ、作業性が向上する
他、素線間の隙間が外力に対して変化しないた
め、コードの中心部迄ゴムが侵入し、素線の腐食
が防止されると共に、タイヤ寿命を大巾に向上す
ることができる。さらに、コードのいずれの横断面においても、
少なくとも１ケ所は素線間に２／100mm以上の隙
間が存在するため、コード内部迄ゴムが侵入す
る。また、自動車走行時において、スチールコード
自体にかかる応力が小さくなるので、スチールコ
ードの耐疲労性を向上し、寿命を延長することが
できる。さらに、単層撚りであるため、多重撚りに比べ
極めて安価に製造できるという多くの優れた実用
的効果を有するものである。 Since the steel cord of the present invention has the above-mentioned structure, a high elongation of 5% or more, which is the same as that of multiple twisting, can be obtained by single-layer twisting, and it has excellent tire wear performance and cut resistance. In addition, since the cord circumscribed circle is elliptical and almost constant in the longitudinal direction of the cord, elongation at low initial loads can be suppressed, improving workability, and the gap between the strands can be reduced against external forces. Since the rubber does not change, the rubber penetrates into the center of the cord, preventing corrosion of the strands and greatly extending the life of the tire. Furthermore, in any cross-section of the cord,
Since there is a gap of 2/100mm or more between the wires in at least one place, the rubber penetrates into the inside of the cord. Furthermore, since the stress applied to the steel cord itself is reduced when the vehicle is running, the fatigue resistance of the steel cord can be improved and its life can be extended. Furthermore, since it is a single-layer twist, it can be produced at a much lower cost than multi-layer twists, and has many excellent practical effects.

[Brief explanation of the drawing]

第１図は本考案のスチールコードの一実施例を
示し、イ，ロ，ハは夫々スチールコードの長手方
向における異なる位置の断面図、第２図は本考案
のスチールコードの他の実施例を示し、イ，ロは
夫々スチールコードの長手方向における異なる位
置の断面図、第３図は撚りピツチと素線径の比と
コードの伸びとの関係を示す曲線図、第４図は長
径と短径の比とゴムの侵入率との関係を示す曲線
図である。１，３……素線、２，４……スチールコード。 Figure 1 shows one embodiment of the steel cord of the present invention, A, B, and C are sectional views at different positions in the longitudinal direction of the steel cord, and Figure 2 shows another embodiment of the steel cord of the present invention. Figure 3 is a curve diagram showing the relationship between the twist pitch, the ratio of the strand diameter, and the elongation of the cord, and Figure 4 is a diagram showing the relationship between the twist pitch, the wire diameter ratio, and the cord elongation. FIG. 3 is a curve diagram showing the relationship between diameter ratio and rubber penetration rate. 1, 3... bare wire, 2, 4... steel cord.

Claims

[Scope of utility model registration request]

In a single-layer open-stranded steel cord in which three to six strands are twisted in the same direction and at the same pitch, the ratio of the strand diameter d to the twist pitch P is 10.
≦P/d≦28, the cord elongation until breakage is 5% or more, and the circumscribed circle of the cord is approximately constant in the longitudinal direction of the cord, and is approximately elliptical, and its minor axis D ₁ and major axis
A steel cord characterized in that the ratio of D ₂ is D ₂ /D ₁ ≧1.1, and furthermore, in any cross section of the cord, there is a gap of 2/100 mm or more at at least one place between the strands.