KR100763762B1 - high tensile steel cord of 2 layer twisted in the different direction - Google Patents

Abstract

The high-strength steel cord of two-layer lead structure having different twisting directions according to the present invention is a two-layer lead 3 + 8 structure having three inner layers and eight outer layers, which are used for tires, and each filament has a diameter of 0.1 to 0.4 mm. The twisting period is 5 to 40mm, and the twisting direction of the inner three wires is different from the twisting direction of the outer eight wires, thereby improving rubber adhesion and reducing tire weight and cost.

Description

High tensile steel cord of 2 layer twisted in the different direction}

1 is a plan view of a high strength steel cord of a two-layer lead structure according to the present invention,

2 is a cross-sectional view of FIG.

<Description of the symbols for the main parts of the drawings>

12: inner layer 14: outer layer

F1: inner layer filament F2: outer layer filament

The present invention relates to a high-strength steel cord having a two-layer lead structure with different twisting directions used for reinforcing rubber products of tires.

Steel cord is especially good for tire reinforcement because it has excellent strength, modulus, heat resistance, heat transfer rate, fatigue resistance and rubber adhesion among various kinds of reinforcement materials used for reinforcement of various rubber products including tires and industrial belts of vehicles. It is widely used, and its usage is increasing day by day.

Steel cords are generally wire-drilled from 5.0 to 5.5 mm in diameter from carbon steel with carbon content of 0.6 to 0.82% by weight to primary diameter 1.0 to 2.5 mm, followed by heat treatment and brass plating. Fresh, multi-filament strands with a diameter of 0.1 to 0.4 mm and a strength of 280 to 320 kgf / mm2, depending on the application (1x2, 1x3, 2 + 2, 2 + 7, 3 + 6, 3 + 8, 3 + 9, 3 + 9 + 15, 1 + 18, 3/8 + 13 etc.)

Double-structured steel cords, in which filaments form two or three layers, have been mainly used as steel cords for trucks and buses. Representative standards of the above-described double-structure steel cord are 3 + 6, 3 + 9, 3 + 9 + 15 steel cord.

Among the double-layered steel cords, a 3 + 9 steel cord having a two-layered lead structure includes a core, a filament located in the inner layer, in which three filaments are twisted in a predetermined direction, and an outer layer surrounding the core has nine filaments. As a structure in close contact with the core layer, there may be additionally a spiral wrap that is a single filament surrounding the outer layer. The three filaments constituting the inner layer are twisted with each other, the outer layer is twisted so that the inner layer and the filament diameter and the twist direction is the same, but the twist length is different, the spiral wrap is twisted in the opposite direction to the twist direction of the outer layer.

However, this steel cord is a normal tensile product with a strength of 280 ~ 300 kgf / mm2 of filament, and its strength is low, so the amount of steel cord used is increased when tires are applied. Since the process of the steel cord has a problem that the unit price of the expensive.

In addition, when the cut section is produced after the production of the steel cord, there is almost no gap between the filament of the outer layer and the inner layer, and the rubber adhesion force is reduced because the rubber penetration into the steel cord is difficult during the rubber topping. The voids between the filaments that are hardly penetrated become their moving passages, and the corrosion of the steel cords is promoted by the repeated bending of the tires, resulting in a problem that the durability of the tires is lowered.

Various attempts have been made to solve this problem. Japanese Patent No. Hei 7-109685 proposes a steel cord with a 3 + 8 structure, which removes one of the outer 9 wires to make a gap, and then again changes the wire diameter of the inner 3 wires and the outer 8 wires to the gap. The rubber permeability was improved, and thus the tire durability was improved. In addition, Japanese Patent No. Hei 10-131065 discloses a method in which the mold of the three inner layers is made larger than the outer 9 lines (or 8 lines) to make a gap to improve rubber penetration into the inner layer. Japanese Patent Laid-Open No. 10-292277 proposes a method of improving rubber penetration by giving a preform to three inner layers.

By the way, the steel cords proposed to improve the rubber permeability of the prior art, as a normal tensile and high tensile steel cord having a strength of 280 ~ 300 kgf / mm 2 and 300 ~ 320 kgf / mm 2 Low strength had a problem in that rolling resistance was reduced due to deterioration in durability or increase in steel cord usage when manufacturing tires.

 Therefore, the present invention has been made to solve the above problems, the object of the present invention is to improve the rubber adhesion and maintain sufficient strength in a small amount to reduce the weight of the tire, reduce the cost and improve fuel economy 2 The present invention provides a high strength steel cord having a layered structure.

The high-strength steel cord of two-layer lead structure having different twisting directions according to the present invention is a two-layer lead 3 + 8 structure having three inner layers and eight outer layers, which are used for tires, and each filament has a diameter of 0.1 to 0.4 mm. The twisting period is 5 to 40 mm, and the twisting direction of the three inner layers and the twisting direction of the eight outer layers are different.

Carbon content of the filament is 0.85 ~ 0.95% by weight and tensile strength after final drawing is 340 ~ 380 kgf / mm2, or 0.85 ~ 0.95% by weight of carbon content of the filament and tensile strength after final drawing is 380 ~ It is 420 kgf / mm <2>.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a plan view of a steel cord according to the present invention, Figure 2 is a cross-sectional view of FIG. As shown, the present invention is a steel cord having a two-layer lead 3 + 8 structure of three inner layers and eight outer layers, each filament F1 (F2) diameter is 0.1 ~ 0.4mm, the twist length (cycle) of the inner layer 12 ) A and the twist length B of the outer layer 14 are 5-40 mm. The twisting directions of the inner and outer layers are different from each other.

In this case, the carbon content of each filament is 0.85 ~ 0.95% by weight and the tensile strength after the final drawing is 340 ~ 380 kgf / mm2, or 0.85 ~ 0.95% by weight of the carbon content of the filament and the tensile strength after the final drawing It is between 380 and 420 kgf / mm2. Tensile strength of the filament is determined according to the carbon content and the number of draw processing.

These filaments are subjected to well-known drawing, heat treatment, and brass plating using wire rods having the carbon content (0.85 to 0.95% by weight), and finally wet fresh after a predetermined diameter (0.1 to 0.4 mm), followed by stranded steel. Molded into a cord.

Example 1

After heating the wire rod with the carbon content of 0.92% by weight and 5.5mm in diameter, heat-treating and brass plating, and final drawing to 0.35mm in diameter to prepare the filament, the three inner layers have 12mm twist length in the S (clockwise) direction. The stranded wire was processed and the outer 8 wires were stranded in the Z (counterclockwise) direction with 18mm twist length to produce 3 + 8 x 0.35 ST steel cord and tested for the physical properties. The results are shown in [Table 1].

Comparative Example 1

After heating the wire rod with carbon content of 0.82% by weight and 5.5mm in diameter, heat-treating and brass plating, and final drawing to 0.35mm in diameter to prepare the filament.The three inner layers have a 9mm twist length in the S (clockwise) direction. Stranded wire processing was carried out, and the outer layer 8 wires were stranded in S (clockwise) direction with 18mm twist length to produce 3 + 8 x 0.35 HT steel cord, and the results of the test were shown in [Table 1].

Example 2

After heating the wire rod with the carbon content of 0.92% by weight and 5.5mm in diameter, heat-treating and brass plating, and final drawing to 0.22mm in diameter to prepare the filament, the three inner layers have a 10mm twist length in the S (clockwise) direction. Stranded wire processing was carried out, and the outer layer 8 wires were twisted in the direction of Z (counterclockwise) with 12mm twist length to produce 3 + 8 x 0.22 ST steel cords, and the results of the test were shown in [Table 1].

Comparative Example 2

After heating the wire rod with carbon content of 0.82% by weight and 5.5mm in diameter, heat-treating and brass plating, and final drawing to 0.22mm in diameter to prepare the filament.The three inner layers have 6mm twist length in the S (clockwise) direction. Stranded wire processing was carried out, and the outer 8 wires were stranded in the S (clockwise) direction with a 12mm twist length to produce 3 + 8 x 0.22 HT steel cords, and the results of the test were shown in [Table 1].

TABLE 1

Item unit Example 1 Comparative Example 1 Example 2 Comparative Example 2 3 + 8x0.35ST 3 + 8x0.35HT 3 + 8x0.22ST 3 + 8x0.22HT Twist length and direction Inner layer - 12mm S 9mm S 10 mm S 6mm S Outer layer - 18mm Z 18mm S 12mm Z 12mm S Small diameter mm 0.35 0.35 0.22 0.22 Cutting load Kgf 320 296 143 132 Unit weight g / m 8.43 8.43 3.35 3.35 Rubber penetration cc / min 150 180 140 160 Coverage % 92 90 95 93 Adhesion kg / 1.0 " 175 165 130 120

Example 3

After heating the wire rod with the carbon content of 0.92% by weight and 5.5mm in diameter, heat-treating and brass plating, and final drawing to 0.35mm in diameter to prepare the filament, the three inner layers have 12mm twist length in the S (clockwise) direction. Stranded wire processing is carried out, and the outer 8 wires are stranded in the direction of Z (counterclockwise) with 18mm twist length to produce 3 + 8 x 0.35 UT steel cord, and tested for their physical properties. [Comparative Example 1] Table 2].

Example 4

After heating the wire rod with the carbon content of 0.92% by weight and 5.5mm in diameter, heat-treating and brass plating, and final drawing to 0.22mm in diameter to prepare the filament, the three inner layers have a 10mm twist length in the S (clockwise) direction. Stranded wire processing is carried out, and the outer layer 8 wires are twisted in the direction of Z (counterclockwise) with 12mm twist length to produce 3 + 8 x 0.22 UT steel cords and tested for their physical properties. [Comparative Example 2] Table 2].

TABLE 2

Item unit Example 3 Comparative Example 1 Example 4 Comparative Example 2 3 + 8x0.35UT 3 + 8x0.35HT 3 + 8x0.22UT 3 + 8x0.22HT Twist length and direction Inner layer - 12mm S 9mm S 10 mm S 6mm S Outer layer - 18mm Z 18mm S 12mm Z 12mm S Small diameter mm 0.35 0.35 0.22 0.22 Cutting load Kgf 330 296 150 132 Unit weight g / m 8.43 8.43 3.35 3.35 Rubber penetration cc / min 150 180 140 160 Coverage % 92 90 95 93 Adhesion kg / 1.0 " 175 165 130 120

Rubber penetration force (cc / min) in the [Table 1] and [Table 2] items are measured by the following method.

Rubber Penetration Force (cc / min): A rubber block having a length of 25.4mm was prepared by coating 6mm thick rubber of Korea A company above and below the manufactured steel cord. Compressed air was blown for 1 hour and the amount of air coming out from the opposite side was measured.

As can be seen from the above table, Examples 1 to 4 are steel cords having different twisting directions between inner and outer layers, and thus, tires can be maintained at a sufficient amount compared to conventional steel cords by improving rubber adhesive force when applying tires. It can reduce the weight, reduce the cost and improve the fuel economy.

According to the high-strength steel cord having a different twisting direction according to the present invention, it is possible to reduce the tire weight, reduce the cost, and improve fuel efficiency by improving rubber adhesion and maintaining sufficient strength in a small amount.

Claims (3)

delete As a two-layer lead 3 + 8 structure with three inner layers and eight outer layers for tires, The diameter of each filament is 0.1 ~ 0.4mm and the twisting period of inner layer and outer layer is 5-40mm, and the twisting direction of the three inner layers and the outer eight layers are different. The carbon content of the filament is 0.85 ~ 0.95% by weight, the tensile strength after the final wire processing is 340 ~ 380 kgf / ㎜ characterized in that the high-strength steel cord having a different twist direction of the two-layer structure. As a two-layer lead 3 + 8 structure with three inner layers and eight outer layers for tires, The diameter of each filament is 0.1 ~ 0.4mm and the twisting period of inner layer and outer layer is 5-40mm, and the twisting direction of the three inner layers and the outer eight layers are different. The carbon content of the filament is 0.85 ~ 0.95% by weight, and the tensile strength after the final wire processing is 380 ~ 420 kgf / ㎜ characterized in that the high-strength steel cord having a different twist direction of the two-layer structure.

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