JP4439622B2 - Steel cord for tire reinforcement - Google Patents

Description

【００２２】
本発明のコードは、３本の素線のうちの１本に撚り合わせのくせとは異なる小さなスパイラル状の小さなくせを施し、他の２本の素線とバンチャー型撚り線機で撚り合わせたのち、小径のフラットローラを千鳥状に配列した矯正機を通すことで押圧加工し、コードの断面を略楕円形状とした。
上記小さなくせ付けは、くせ付け装置上に設けた複数個のピン間に素線を通し、かつその素線を軸芯として、そのくせ付け装置を高速回転させて施した。
小さなくせ付けを施した１本の素線と小さなくせを施さない他の２本の素線には、撚りの集合点前に設けられた３本のくせ付けコーンピン間を通すことにより、撚りのためのスパイラル状のくせ付けを行ってあるが、押圧加工によって偏平形状にしやすくするため、コードがオープン構造となるようやや過大なくせを施した。
【００２３】
ゴム浸入率は、各コードに５ｋｇの引張り荷重をかけた状態でゴムに埋設して加硫した後、コードを抜き取り、その素線を引き剥がして素線全周を観察し、ゴム材と接触した面積率を表示した。
【００２４】
耐疲労性は、各コードを複数本ゴムシートに埋め込み、このシートで３点曲げ疲労試験機により評価し、実験Ｎｏ．１のクローズド撚りコードを１００として指数表示した。数値が大きいほど耐疲労性に優れる。
【００２５】
また、撚りの安定性、コード取扱作業性および撚線加工性も合わせて評価した。
評価は、実験Ｎｏ．１のクローズド撚りコードと比較して、非常に劣るものを×、少し劣るものを△、差がないものを○として評価した。
【００２６】
表１より明らかなように本発明のコードは評価項目を全て満足し、ゴム製品の補強材として最適である。
【００２７】
【発明の効果】
本発明のタイヤ補強用スチールコードは上記構成であるため、コード短径側に大きな隙間が形成され、この隙間がコード内部へのゴムの浸入路となってゴムが充分に浸入する。したがって、セパレーション現象、錆によるコード強力の低下を防止できる。
また、撚り構造が安定しており、素線の片寄りが生じたり、撚りが不均一になったりすることがなく、低荷重での伸びも小さいため、取扱性および複合体シート成形時の作業性も優れている。
【図面の簡単な説明】
【図１】本発明のスチールコードの実施の形態を示し、（ａ）は概略平面図、（ｂ）は部分断面図である。
【図２】本発明のスチールコードの素線の状態を示し、（ａ）は素線２の概略説明図、（ｂ）は素線１の概略説明図である。
【図３】従来のスチールコードの例を示し、（ａ）は概略平面図、（ｂ）は部分断面図である。
【図４】従来のスチールコードの別の例を示し、（ａ）は概略平面図、（ｂ）は部分断面図である。
【符号の説明】
１、２、４、６ 素線
３、５、７ スチールコード
Ｈ、Ｓ 隙間
Ｅ 空洞部
Ｌ コード長手方向の中心軸[0001]
[Industrial application fields]
The present invention relates to a tire reinforcing steel cord (hereinafter simply referred to as “cord”) used for an automobile tire.
[0002]
[Prior art]
In general, a so-called closed twisted cord 5 in which three strands 4 as shown in FIG. 3 are closely twisted together is used for this type of cord.
And the said code | cord | chord 5 is coat | covered with rubber | gum in the state with which the multiple pieces were arranged in parallel, and is used as a reinforcement material of the tire for motor vehicles.
Incidentally, an indispensable requirement as a tire reinforcing material is excellent fatigue resistance. In other words, if the cord has excellent strength and is a complete composite with rubber and has excellent fatigue resistance, it will greatly extend the life of the tire and increase safety, and it will serve as a tire reinforcement. Can fully fulfill.
However, in the cord 5, since the strands 4 constituting the cord are in close contact and twisted together, the rubber is corded between the strands 4 and 4 when the composite sheet of cord and rubber is formed. It cannot penetrate into the inside, and only covers the outer periphery of the cord, and the cavity E continuously exists in the inside of the cord over the length of the cord.
[0003]
For this reason, when this cord 5 is used for a tire, the adhesion between the rubber and the cord is not sufficient, so that the cord and the rubber are peeled off during driving of the automobile, so-called separation phenomenon is caused, and the function of the tire is significantly reduced. Moisture in the rubber and water that has entered from the tire scraps reach the cavity E inside the cord and propagate in the cord longitudinal direction to corrode the cord, leading to a decrease in the mechanical strength of the cord and improving fatigue resistance. It will be greatly reduced.
[0004]
In view of the above circumstances, various cords having a structure capable of improving the adhesion between the cord and rubber have been proposed.
[0005]
For example, in Japanese Patent Laid-Open No. 55-90692, there is a cord 7 referred to as a so-called open twisted cord that is twisted and twisted while providing a gap H between the strands 6 and 6 as shown in FIG. It is disclosed.
[0006]
In the cord 7, in order for the rubber material to sufficiently enter the cord, the gap H between the strands 6 and 6 needs to be 0.01 mm or more.
However, when the gap H is sufficiently large, the free space in which each strand 6 can move becomes large, and the twisted structure tends to become unstable at the time of manufacturing the cord, so that the strand 6 is displaced or the twist is not uniform. It becomes.
[0007]
Further, since the cord 7 has a large elongation under a low load, the handling property and the workability at the time of molding the composite sheet are not only poor, but the gap H is reduced by the low load tension applied at the time of molding the composite sheet. After all, it becomes the same as the cord 5 shown in FIG. 3, and the rubber does not sufficiently penetrate into the inside of the cord, so that it does not form a complete composite with the rubber, causing the above-mentioned adverse effects.
[0008]
[Problems to be solved by the invention]
This invention is made | formed in view of the subject of the said prior art, and makes it a subject to provide the code | cord | chord which the twisted structure was stabilized, the rubber | gum penetration property was excellent, and was excellent in handling workability | operativity.
[0009]
In order to solve the above-mentioned problems, a steel cord for reinforcing tires according to the present invention passes one strand of the three strands between a plurality of pins provided on the brazing device, and the strand By rotating the brazing device with the axis as the axis, a small spiral in the shape different from the twisting twist is applied to the strand, and one small strand and a small strand are not applied. The other two strands are passed between a plurality of bracing cone pins to give the three strands spiral twist for twisting, and the three strands are twisted simultaneously to form a circular cross section. Steel cord with a 1x3 flat open structure consisting of three strands obtained by making a steel cord and pressing the steel cord, and having an elliptical cross-section in the same direction in the longitudinal direction so I, the coding longitudinal central axis in the plane of the minor axis, the two wires 1,1 are sinusoidal having a phase difference, the wire 2 of another one is the small by the pressing process It is a trapezoidal wave shape in which small spirals are elongated , and any two strands are in contact with each other on the surface on the long diameter side.
[0010]
In the cord of the present invention, the two strands are substantially sinusoidal and the other one is substantially trapezoidal on the surface on the short diameter side. Is formed.
[0011]
In addition, since any two strands are almost in contact with each other on the surface on the long diameter side, a free space in which the strands can move is limited, and elongation when a load is applied can be suppressed, and the shape is stabilized.
[0012]
In the cord of the present invention, one strand is preliminarily provided with a small spiral-like twist different from the twisted strand (this strand is hereinafter referred to as “spiral strand”), and this strand and the other two strands. A strand having no small habit (hereinafter referred to as “straight strand”) is simultaneously twisted to form a cord having a circular cross section, and this cord can be manufactured by pressing. At this time, the spiral wire has a substantially trapezoidal wave shape, and the straight wire has a substantially sine wave shape.
[0013]
The reason why the spiral wire is substantially trapezoidal by pressing is that the actual length of the strand at one twist pitch is different between the spiral wire and the straight wire (the spiral wire is long).
That is, the cross-sectional shape of the cord becomes a flat shape by the pressing process, but the spiral shape is also deformed by the pressing process.
[0014]
In the present invention, the reason why the cord has an open structure is not to increase the gap between the strands to improve rubber penetration, but to facilitate flattening and to further increase the gap.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1A is a schematic plan view showing a short diameter side surface of a cord having a 1 × 3 structure whose cross-sectional shape is substantially elliptical, showing an embodiment of the present invention, and FIG. It is a fragmentary sectional view which shows arrangement | positioning of each strand.
FIGS. 2A and 2B are schematic explanatory views showing the state of each strand in FIG.
[0017]
As shown in FIG. 1A and FIGS. 2A and 2B, the strand 1 has a substantially sinusoidal shape with respect to the central axis L in the cord longitudinal direction, and the strand 2 has a substantially trapezoidal waveform.
Further, as shown in FIG. 1B, the cord is such that any two strands are substantially in contact with each other on the long diameter side surface.
[0018]
In the cord of the present invention, since a large gap S is formed between the wire 1 and the wire 2 as shown in FIG. 1, rubber easily enters from the gap S. Further, since the strands are substantially in contact with each other on the long diameter side, the free space in which the strands can move is limited, the elongation when a load is applied can be suppressed, and the shape is stabilized.
[0019]
【Example】
Next, an example of the present invention will be specifically described by comparing with a conventional example.
[0020]
Table 1 shows the test results of cords having various configurations in which a plurality of strands whose surfaces are subjected to brass plating are twisted together. This test result is obtained by manufacturing the cord of the present invention and the cord of the conventional example, and comparing the rubber penetration property, fatigue resistance, twist stability and workability in each cord.
[0021]
[Table 1]

[0022]
In the cord of the present invention, one of the three strands is provided with a small spiral shape that is different from the twisted strand, and then twisted with the other two strands with a buncher-type strand wire machine. After that, it was pressed by passing it through straightening machines in which small-diameter flat rollers were arranged in a staggered manner, and the cross section of the cord was made into an approximately elliptical shape.
The small soldering was performed by passing a strand between a plurality of pins provided on the brazing device and rotating the brazing device at a high speed using the strand as an axis.
One strand with small clinging and the other two strands without small wrinkling are passed between the three bracing cone pins provided before the twisting point, In order to make it easier to obtain a flat shape by pressing, the cord is slightly oversized so that it has an open structure.
[0023]
The rubber penetration rate was determined by placing each cord under a tensile load of 5 kg and burying it in rubber and vulcanizing it, then pulling out the cord, peeling off the strand, observing the entire circumference of the strand, and contacting the rubber material The area ratio was displayed.
[0024]
For fatigue resistance, each cord was embedded in a plurality of rubber sheets, and this sheet was evaluated with a three-point bending fatigue tester. The index was expressed as 1 closed twist cord of 100. The larger the value, the better the fatigue resistance.
[0025]
In addition, the stability of twisting, cord handling workability and twisting workability were also evaluated.
The evaluation was conducted in Experiment No. As compared with the closed twisted cord of No. 1, a very inferior one was evaluated as x, a little inferior one was evaluated as Δ, and a one having no difference was evaluated as ○.
[0026]
As apparent from Table 1, the cord of the present invention satisfies all the evaluation items and is optimal as a reinforcing material for rubber products.
[0027]
【The invention's effect】
Since the steel cord for reinforcing tires of the present invention has the above-described configuration, a large gap is formed on the side of the short axis of the cord, and this gap serves as a rubber intrusion path into the inside of the cord, and the rubber sufficiently enters. Accordingly, it is possible to prevent a reduction in cord strength due to separation phenomenon and rust.
In addition, the twisted structure is stable, the strands are not displaced, the twist is not uneven, and the elongation at low load is small. It has excellent properties.
[Brief description of the drawings]
FIG. 1 shows an embodiment of a steel cord according to the present invention, in which (a) is a schematic plan view and (b) is a partial sectional view.
FIGS. 2A and 2B show a state of a strand of a steel cord according to the present invention, where FIG.
FIG. 3 shows an example of a conventional steel cord, where (a) is a schematic plan view and (b) is a partial cross-sectional view.
4A and 4B show another example of a conventional steel cord, in which FIG. 4A is a schematic plan view, and FIG. 4B is a partial cross-sectional view.
[Explanation of symbols]
1, 2, 4, 6 Wires 3, 5, 7 Steel cord H, S Gap E Cavity L Center axis of cord longitudinal direction

Claims (1)

One strand of three strands is passed between a plurality of pins provided on the brazing device, and twisting is performed by rotating the brazing device around the strand as an axis. Apply a small spiral-shaped small wire different from the wire, and pass between one corn wire and the other 2 non-small wire wires between multiple corn pins. The three strands are spirally twisted for twisting, and the three strands are twisted at the same time to produce a steel cord with a circular cross section, and the steel cord is pressed. 1 × 3 flat open structure consisting of three strands, and a steel cord whose cross-sectional shape is an elliptical shape in the same direction in the longitudinal direction, and is on the central axis in the cord longitudinal direction on the short diameter side surface In contrast, two Wires 1,1 are sinusoidal having a phase difference, the wire 2 of another one is a trapezoidal waveform that habit small of the small spiral is extended by the pressing process, either in terms of major axis side 2 A steel cord for reinforcing tires, characterized in that the strands of the book come into contact with each other.

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