JPH10168770A - Rubber article reinforcing steel cord, production thereof and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject steel cord, capable of elevating a bending stiffness in a plain without increasing an out of a plain bending stiffness, and improving the steering stability by bundling plural filament without twisting, forming a strand under a specific condition and then twisting. SOLUTION: This rubber article reinforcing steel cord is obtained by preparing plural spools wound with filament bundles 2A to 2D formed by bundling plural filaments 1a to 1h without twisting, setting the spools on a tubular twisting machine, unwinding filament bundles 2A to 2D from each of the spools for introducing them into the twisting machine, twisting the plural filament bundles 2A to 2D to form strands 3A and 3B, and twisting 2-4 obtained strands of 3A, 3B. Further, it is preferable to arrange the steel cord in a belt layer so as to lay the longer diameter thereof along the width direction of the belt for constituting a pneumatic tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord used as a reinforcing material for rubber articles such as pneumatic tires and industrial belts, and more particularly to an advantageous improvement in bending rigidity.

[0002]

2. Description of the Related Art It is advantageous to increase the cornering force generated in a direction perpendicular to the traveling direction of a vehicle for a constant input steering in order to improve the steering stability when the vehicle is running. In order to increase the cornering force, it is necessary to increase the lateral slip deformation of the tread land portion that occurs in the contact area of the tire when the tire rolls. This lateral slip deformation amount is determined by the deformation of the belt supporting the tread land portion of the tire due to the cornering force, that is, the belt ply shown in FIG. 1 (a) and the belt ply shown in FIG. 1 (b).
It is affected by deformation (hereinafter, referred to as in-plane bending deformation) that occurs in the direction along the surface of each layer of the belt. That is, in order to generate a large cornering force, it is preferable to suppress in-plane bending deformation of the belt portion, and therefore, it is required to have a high ability to resist in-plane bending deformation (hereinafter, referred to as in-plane bending rigidity). .

Further, in order to obtain excellent vibration riding comfort, it is effective to secure a ground contact area even with a slight unevenness on the road surface. It is required to have a low ability to resist deformation occurring in a direction perpendicular to the plane (hereinafter, referred to as out-of-plane bending stiffness).

Therefore, it is necessary to optimize the bending stiffness required for a tire belt in different directions, in-plane and out-of-plane, respectively. Affected by For example, the bending rigidity of the belt can be increased by using a steel cord having high bending rigidity or by increasing the number of steel cords driven into the belt.

However, since the conventional cord has a substantially circular cross-sectional shape, the characteristic in the cord radial direction is isotropic. Even if the filament is increased in diameter, the rigidity is increased equally. As a result of increasing both the in-plane bending stiffness and the out-of-plane bending stiffness, it is difficult to increase the in-plane bending stiffness of the belt while reducing the out-of-plane bending stiffness.

On the other hand, there has been proposed a cord having so-called anisotropy, in which the bending rigidity of the cord varies depending on the direction in which the cord is bent. For example, a code having anisotropy by regulating the contour shape of the code to an ellipse is known. By arranging the cords in such a direction that their major diameters are along the belt width direction, the in-plane bending stiffness of the belt is increased while the out-of-plane bending stiffness is reduced.

However, even if the cord has an elliptical contour, the desired anisotropy cannot be obtained, and the flexural rigidity of the cord is substantially equal to the sum of the flexural rigidities of the filaments constituting the cord. This is because when each filament constituting the cord is bent and deformed with the cord axis as a neutral axis, the filament is subjected to the same tension and compression in a half pitch length, and the filament is displaced in the cord axis direction. The elliptical shape eliminates the introduced distortion and does not exhibit anisotropy.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a belt material for a tire which has high in-plane bending rigidity and low out-of-plane bending rigidity. The present invention provides a steel cord having a significantly different bending stiffness and a method of manufacturing the cord.

[0009]

That is, the present invention provides:
A plurality of steel filaments are juxtaposed without twisting to form a bundle of filaments, a plurality of bundles of the filament bundle are twisted without twisting to form a strand, and a plurality of the strands are twisted without twisting. It is a steel cord for reinforcing rubber articles.

Here, it is advantageous that the filament bundle is composed of 2 to 4 filaments, the strand is composed of 2 to 5 bundles of filaments, and the cord is composed of 2 to 4 strands. Complies with

The above-mentioned steel cord is provided with a plurality of spools each of which is wound with a filament bundle in which a plurality of filaments are bundled without being twisted, and is set in a tubular twisting machine. Is wound and guided to a twisting machine, a plurality of filament bundles are twisted to form a strand, and two to four strands thus obtained are twisted to produce a production method.

Further, according to the present invention, a carcass composed of plies of a radial sequence code extending in a toroidal shape between a pair of bead portions is used as a skeleton, and at least one carcass is provided on the carcass.
A pneumatic radial tire having a layered belt, wherein the steel cord is applied to the belt in such a manner that its major axis is arranged along the width direction of the belt.

2 to 6 show a steel cord for reinforcing a rubber article according to the present invention. These steel cords consist of a filament bundle 2A in which two steel filaments 1A and 1B are juxtaposed without twisting, and
A strand 3A formed by twisting the filament bundle 2B without twisting the steel filaments 1C and 1D side by side without twisting, and the two steel filaments 1C and 1D
A strand 3B formed by twisting a filament bundle 2C formed by E and 1F and a filament bundle 2D formed by two steel filaments 1G and 1H without twisting is twisted without twisting.

The steel cord according to the present invention is characterized in that there is no twist in the twisting of filament bundles and the twisting of strands, and the twisting direction and twist pitch between filament bundles and strands can be arbitrarily determined. Can be set. Incidentally, FIGS. 2 and 3
In the cord shown in FIG. 4, the twist pitch between the filament bundles is half of the twist pitch between the strands, and the remaining FIGS.
The cord shown in FIG. 6 is an example in which the twist pitch between filament bundles and the twist pitch between strands are the same. In addition, the twist direction is the same between filament bundles and strands in all examples, except that the cords shown in FIG. 6 are reversed between filament bundles and strands.

The cords obtained in accordance with the above-mentioned regulations have significantly different bending stiffnesses in two directions crossing each other in the cross section of the cords. Therefore, in a tire to which this cord is applied to a belt, the bending stiffness of the belt is given anisotropy. can do. That is, when the filament bundles that are juxtaposed without twisting the filaments are twisted without twisting, in the bending deformation with the cord axis as the neutral axis, the compressive strain and the tensile strain that occur alternately in the longitudinal direction of the filament, As a result of the different sizes, anisotropy is imparted to the bending stiffness. Furthermore, since the strands are twisted without being twisted, the anisotropy imparted to the strands is not eliminated.

The number of filaments constituting the filament bundle and the number of filament bundles constituting the strand may be plural, but the filament bundle is made up of 2 to 4 filaments and 2 to 5 filament bundles. And a cord from 2 to 4 strands, respectively. Furthermore, the number of hits when applying the above code to the tire belt,
It is preferable that the thickness is about 18 to 25/50 mm.

In order to manufacture the steel cord of the present invention, first, two to four filaments are bundled without twisting, and then wound around a spool.
Prepare it individually, set it in a tubular stranded wire machine, wind up the filament bundle from each spool, guide it to the stranded wire machine,
Five filament bundles are twisted to form a strand. Two to four strands thus obtained are similarly twisted to obtain a cord.

Further, the cord according to the present invention is applied to, for example, a belt of a pneumatic tire shown in FIG. Increase rigidity,
Deformation during cornering of the tire can be suppressed.
On the other hand, since the out-of-plane bending stiffness of the belt is reduced, the grounding property against unevenness of the road surface is improved. Therefore, the performance of the entire tire is improved, and a tire having particularly excellent steering stability can be obtained. The pneumatic tire shown in FIG. 7 includes a carcass 5 extending in a toroidal shape between a pair of bead cores 4, a two-layer belt 6 and a belt 6 arranged, for example, in a tire radial direction outside a crown portion of the carcass 5. Of the tread 7 arranged on the outer side in the tire radial direction.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS.
Steel cords having the structures shown in FIGS. 4, 5, and 6, and FIGS. 8 to 10 were respectively manufactured under the specifications shown in Table 1, and each steel cord was applied to the belt with the number of shots shown in the same table. The tire having the structure shown in FIG. The belt 6 has a first belt layer 6a disposed on the carcass 5 in such a direction that the steel cord is inclined at an angle of 22 ° to the left with respect to the equatorial plane of the tire. The second belt layer 6b is arranged in such a manner that the steel cord is inclined at an angle of 22 degrees to the right.

The tires thus obtained were mounted on a specified rim, filled with a specified internal pressure, mounted on a passenger car, and evaluated by three drivers who traveled 50,000 km on a paved road. I went for comfort. This feeling evaluation was given on a scale of 1 to 3.
The average value of human drivers was calculated. These evaluation results are also shown in Table 1.

[0021]

[Table 1]

[0022]

As described above, the cord of the present invention has a high anisotropy in bending stiffness. Therefore, when the cord is used for, for example, a tire belt, in-plane bending without increasing out-of-plane bending stiffness. The rigidity can be increased, and the steering stability can be increased without lowering the grip force during tire running, which is extremely useful in industry.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating bending rigidity of a tire belt.

FIG. 2 is a diagram showing a code structure of the present invention.

FIG. 3 is a diagram showing a code structure of the present invention.

FIG. 4 is a diagram showing a code structure of the present invention.

FIG. 5 is a diagram showing a code structure of the present invention.

FIG. 6 is a diagram showing a code structure of the present invention.

FIG. 7 is a diagram showing a tire structure of the present invention.

FIG. 8 is a schematic diagram showing a conventional code structure.

FIG. 9 is a schematic diagram showing a conventional code structure.

FIG. 10 is a schematic diagram showing a comparative code structure.

[Explanation of symbols]

 1a to 1h filament 2a to 2d filament bundle 3a, 3b strand 4 bead core 5 carcass 6 belt 6a first belt layer 6b second belt layer 7 tread

Claims (6)

[Claims] 1. A plurality of steel filaments are juxtaposed without twisting to form a bundle of filaments, a plurality of bundles of the filament bundle are twisted without twisting to form a strand, and a plurality of the strands are not twisted. Steel cord for reinforcing rubber articles made by twisting 2. The steel cord for reinforcing rubber articles according to claim 1, wherein the filament bundle is composed of 2 to 4 filaments. 3. The steel cord for reinforcing a rubber article according to claim 1, wherein the strand comprises a bundle of 2 to 5 filaments. 4. The steel cord for reinforcing rubber articles according to claim 1, wherein the cord comprises 2 to 4 strands. 5. A plurality of spools on which a filament bundle in which a plurality of filaments are bundled without being twisted are prepared, set in a tubular twisting machine, and the filament bundle is wound from each spool and twisted. A method for producing a steel cord for reinforcing rubber articles, characterized in that a strand is formed by twisting a plurality of filament bundles into a machine, and two to four strands thus obtained are twisted. 6. A pneumatic radial tire having a carcass comprising a ply of radially arranged cords extending in a toroidal shape between a pair of bead portions as a skeleton, and having at least one belt layer on the carcass, A pneumatic radial tire, wherein the steel cord according to claim 1 is applied to the belt layer in an arrangement having a major axis along a width direction of the belt.