JPH11181687A - Steel cord and steel radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel cord having good rubber permeability and excellent productivity without deteriorating strength, and to provide a steel radial tire. SOLUTION: This steel cord A comprises a core 2 comprising 2-4 filaments and two or three twisted layers formed on the core, and is used in a state embedded in a rubber molded product for reinforcing the rubber molded product. Therein, the characteristic of steel cord comprises having a spiral wire 6 wound on at least one of the core 2, the filament of the core 2 and the first sheath 4 twisted around the core 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a steel cord used for a rubber molded product such as a steel radial tire and a conveyor belt, and a steel radial tire using the same.

[0002]

2. Description of the Related Art Steel cords are widely used as reinforcing materials for rubber molded products such as pneumatic steel radial tires. As a conventional steel cord, in order to increase the cord cutting load per diameter of the cord and obtain good fatigue resistance, a filament having the same wire diameter is twisted by changing the twist pitch for each layer to be 2-3. There are layered cords. Further, as another conventional steel cord, there is a cord having a multiple twist structure in which a plurality of filaments are twisted into a strand, and a plurality of the strands are twisted.

[0003] Further, a steel cord used for a heavy load tire has a close-packed structure in which steel filaments are twisted in the same direction and at the same pitch in order to increase the cord cutting load.

[0004]

However, the conventional steel cord has the disadvantage that the rubber does not easily penetrate into the cord, so that the corrosion propagation is extremely low and the corrosion resistance is poor. In particular, 2-3
In the layered cord, when the core has 2 to 4 cores, the rubber does not penetrate to the center of the core. This causes a problem that it propagates from the portion in the longitudinal direction of the cord and corrodes the entire cord.

In order to avoid these problems, there is a steel cord in which a gap is provided between filaments by applying a corrugated pattern to the core filament in order to allow the rubber to penetrate into the inside of the core. In a steel cord having a complicated twisted structure such as twisting, the contact pressure between filaments is large, so that the cord shape becomes unstable and the fatigue resistance tends to be inferior.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a steel cord having excellent rubber permeability and improved corrosion propagation resistance without impairing the fatigue resistance of the cord. Aim. It is another object of the present invention to provide a steel radial tire reinforced with such a steel cord.

[0007]

Means for Solving the Problems The inventors of the present invention have proposed a conventional method.
In order to eliminate the drawbacks of the three-layer stranded steel cord, intensive studies were conducted on cords of various configurations, and various studies were repeated. As a result, the following was found. The whole core constituting the steel cord or the constituent filament of the core or the first core
It has been found that when a spiral wire is wound around one of the sheaths, the corrosion propagation resistance can be improved without impairing the fatigue resistance of the cord. Based on such knowledge, the present inventors have completed the present invention.

[0008] The steel cord according to the present invention is a two- or three-layer twisted steel cord having a core of 2 to 4 filaments used for embedding in a rubber molded body to reinforce the rubber molded body. , A spiral wire wound around at least one of the core, the filament of the core, and a first sheath twisted around the core.

[0009] The steel radial tire according to the present invention comprises:
A rubber molded body, and a steel cord embedded in the rubber molded body, wherein the steel cord is a two- or three-layer twist having a core having 2 to 4 filaments;
It has a spiral wire wound around at least one of the filament of the core and the first sheath twisted around the core.

[0010] Further, a plurality of strand cords may be twisted to form a multi-layer twisted structure. The material of the spiral wire is preferably steel. The effective diameter of the spiral wire is preferably 0.15 mm or less.

Further, the constituent wire has a tensile strength of 30.
It is desirable to use a high-tensile steel wire of 0 to 360 kgf / mm ² . This is because, in order for the steel cord to obtain a desired breaking strength, the tensile strength of the wire needs to be 300 kgf / mm ² or more. On the other hand, when the tensile strength of the wire is 3
If it exceeds 60 kgf / mm ² , the wire becomes brittle and the wire is likely to break. In this case, it is particularly preferable to use a high-tensile steel wire having a tensile strength in the range of 330 to 340 kgf / mm ² .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various preferred embodiments of the present invention will be described below with reference to the accompanying drawings. (Example 1) A steel cord 1A having a cross-sectional configuration shown in Fig. 1 was manufactured using a cradle type twisted wire machine described in JP-A-5-302283 or a similar twisted wire machine. In the steel cord 1A of the first embodiment, the number of filaments in the core portion 2 is two, and the number of filaments in the side portion (first sheath) 4 is five. A spiral wire 6 is wound around the core 2.

The manufacturing conditions and the product size of the steel cord 1A of Example 1 are shown below. In addition, the core part 2 and the side part 4 may be twisted separately or may be twisted collectively.

Number of core wires; 2 Number of side wires; 5 core wire diameter D ₁ ; 0.20 mm side wire diameter D ₂ ; 0.37 mm cord twist pitch; 18.0 mm cord twist Direction; S twist Spiral wire diameter D ₃ ; 0.05 mm Spiral twist pitch; 6.0 mm Tensile strength of the constituent wire; 340 kgf / mm ² (Example 2) The same cradle type twisted wire machine as that in Example 1 was used. Steel cord 1 with cross section shown in Fig. 2
B was produced. The steel cord 1B of the second embodiment is the core 2
Has three filaments, and the side (first sheath) 4 has six filaments. A spiral wire 6 is wound around the core 2.

The manufacturing conditions and the product size of the steel cord 1B of Example 2 are shown below. Number of core wires; 3 Number of side wires; 6 Core wire diameter D ₁ ; 0.20 mm Side wire diameter D ₂ ; 0.37 mm cord twist pitch; 18.0 mm cord twist direction; Twist Spiral wire diameter D ₃ ; 0.05 mm Spiral twist pitch; 6.0 mm Tensile strength of constituent wire; 340 kgf / mm ² (Example 3) Drawing using the same cradle type twisting machine as in Example 1 above. Steel cord 1 with cross-sectional configuration shown in 3
C was produced. The steel cord 1C of the third embodiment is the core 2
Has three filaments, and the side (first sheath) 4 has six filaments. One of the constituent wires of the core 2 is wound with a first spiral wire 6a, and the entire core 2 is wound with a second spiral wire 6b.

The manufacturing conditions and the product size of the steel cord 1C of Example 3 are shown below. Number of core wires; 3 Number of side wires; 6 Core wire diameter D ₁ ; 0.20 mm Side wire diameter D ₂ ; 0.37 mm cord twist pitch; 18.0 mm cord twist direction; Twist Diameter D ₃ of the first spiral wire; 0.05 mm Twist pitch of the first spiral wire; 3.5 mm Diameter D ₄ of the second spiral wire; 0.05 mm Twist pitch of the second spiral wire; 6.0 mm Tensile strength of the constituent wire 340 kgf / mm ² (Example 4) A steel cord 1 having a cross-sectional configuration shown in FIG.
D was manufactured. In the steel cord 1D of Example 4, the number of filaments of the core portion 2 is 3, the number of filaments of the first sheath (side portion) 2a is 9, and the number of filaments of the outer layer portion 8 is 15. A spiral wire 6 is wound around the first sheath 2a. In the fourth embodiment, some of the nine outer peripheries of the cord core 3/9 are corrugated to secure desired rubber permeability.

The manufacturing conditions and the product size of the steel cord 1D of Example 4 are shown below. Number of wires at the core; 3 Number of wires at the side; 9 Number of wires at the outer layer portion; 15 Diameter D ₁ of the core wire and the first sheath; 0.195 mm Diameter D _{2 of the} side wire; 0.220 mm Twist pitch: 18.0 mm Cord twist direction: S twist Spiral wire diameter D ₃ ; 0.05 mm spiral twist pitch: 6.0 mm Tensile strength of constituent wire: 340 kgf / mm ² (Example 5) Using the same cradle type stranded wire machine as above, a steel cord 1 having a sectional configuration shown in FIG.
E was produced. In the steel cord 1E of Example 5, the number of filaments of the core portion 2 is 3, the number of filaments of the first sheath (side portion) 4 is 10, and the number of filaments of the outer layer portion 8 is 16.

One of the constituent wires of the core 2 has a first wire.
Spiral wire 6a is wound around the core 2 and the second spiral wire 6b is wound around the entire core portion 2.
A third spiral wire 6c is wound around the sheath 4.

The manufacturing conditions and product size of the steel cord 1E of Example 5 are shown below. Number of wires at the core; 3 Number of wires at the side; 10 Number of wires at the outer layer portion: 16 Diameter D ₁ of the core wire and the first sheath; 0.180 mm Diameter D _{2 of the} side wire; 0.215 mm Twist pitch; 18.0 mm Cord twist direction; S twist First spiral wire diameter D ₃ ; 0.05 mm First spiral twist pitch; 3.5 mm Second spiral wire diameter D ₄ ; 0.05 mm second spiral twist pitch of; tensile strength of 6.0mm configuration wire;; 6.0mm third spiral wire diameter D _5; 0.05 mm third spiral twist pitch 340kgf / mm ² (Comparative example) in the above examples 1 to 5 and For comparison, a conventional tight steel cord having a (3 + 6) configuration was manufactured as a comparative example.

The manufacturing conditions and the product size of the steel cord of the comparative example are shown below. Number of core wires; 3 Number of side wires; 6 Core wire diameter D ₁ ; 0.20 mm Side wire diameter D ₂ ; 0.35 mm Cord twist pitch; 18.0 mm Cord twist direction; Twist Tensile strength of constituent wire; 340 kgf / mm ² Cord breaking load; 202.0 kgf [Evaluation of rubber permeability] Each of the steel cords of Examples 1 to 5 was evaluated for rubber permeability as compared with the steel cord of Comparative Example. .

The rubber permeability was evaluated as follows. First, a steel cord having a length of 20 pitches is prepared for each of the embodiment, the conventional example, and the comparative example. The side wire of each cord is peeled off, and a visual inspection of the rubber permeation state at a total of 40 places at each of the front and rear peaks is visually performed with the naked eye.

A score system was adopted for visual inspection. If 5 points are where the rubber has completely penetrated, 2.5 points where the rubber has penetrated about half and 0 points where the rubber has not penetrated, a total of 100 points in the table Point or back 100
A total of several points were examined. Furthermore, these scores were summed and divided by 2 to obtain an average score, which was expressed as a percentage to evaluate rubber permeability. Those having a rubber permeability of 90% or more were judged to be acceptable.

The results of Examples, Comparative Examples and conventional products are shown below.

[0024]

The steel cord of the present invention has good rubber permeability and excellent productivity without impairing the strength. Further, the steel cord of the present invention can secure a sufficient pitch interval in the calendering process without impairing the breaking strength, and can lay a large number of wires on the rubber sheet, so that high strength and A highly durable steel radial tire can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a steel cord according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a steel cord according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a steel cord according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a steel cord according to a fourth embodiment of the present invention.

FIG. 5 is a transverse sectional view showing a steel cord according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1A, 1B, 1C, 1D, 1E: steel cord, 2: core (core), 2a, 4: first sheath (side), 6, 6a, 6b, 6c: spiral wire, 8: second sheath ( Outer layer).

Claims (5)

[Claims] 1. A two- or three-layer twisted steel cord in which the number of filaments of a core used for embedding in a rubber molded body to reinforce the rubber molded body is two to four. A steel cord comprising: a filament in a core; and a spiral wire wound around at least one of a first sheath twisted around the core. 2. A multi-layer stranded structure in which a plurality of strand cords are twisted together.
The stated steel cord. 3. The steel cord according to claim 1, wherein the material of the spiral wire is steel. 4. An effective diameter of the spiral wire is 0.1.
The steel cord according to claim 1, wherein the steel cord has a diameter of 5 mm or less. 5. A rubber molded article, and a steel cord embedded in the rubber molded article, wherein the steel cord is a two- or three-layer twisted filament having a core of 2 to 4 filaments, And a spiral wire wound around at least one of the filament of the core and the first sheath twisted around the core.