KR20080073835A - 1+(3/8) type steel cord for tire of vehicle - Google Patents

Abstract

A 1+(3/8) type steel cord for a tire of a vehicle is provided to stabilize a twisted structure by preventing 3 inner layers from migrating in a twisted direction of 8 outer layers. A 1+(3/8) type steel cord for a tire of a vehicle comprises as follows. Three steel wires of an inner layer are covered, which twist around a circumferential surface of one steel wire that is positioned in the innermost layer. In addition, 8 steel wires of an outer layer is covered, which twist a circumferential surface of the 3 steel wires of the inner layer.

Description

{1+ (3/8) type steel cord for tire of vehicle}

1 is a cross-sectional explanatory diagram of a steel cord having a 1+ (3/8) structure according to the present invention;

Figure 2 is a cross-sectional explanatory diagram of a steel cord of the existing 3 + 8 structure.

Figure 3 is a cross-sectional explanatory view of a steel cord of a conventional preform having a 3 + 8 structure.

Steel cord is a tire reinforcing material because it has excellent strength, modulus, heat resistance, heat transfer rate, fatigue resistance and rubber adhesiveness among various kinds of reinforcing materials used to reinforce various rubber products including tires and industrial belts of vehicles. In particular, it is widely used and its usage is increasing day by day.

Steel cords are usually wire drawn with a diameter of 5.0 ~ 5.5mm from carbon steel with 0.6 ~ 0.95% by weight of primary wire 1.0mm to 2.5mm in diameter, then heat treated and brass plated, and finally drawn again. Various structures of filament with 0.1 ~ 0.4mm diameter and 280 ~ 380kg / mm2 strength (1 × 2, 1 × 3, 2 + 2, 2 + 7, 3 + 6, 3 + 8, 3 + 9) Produces stranded wire with +15, 1 + 18, 3/8 + 13, etc.).

The double-stranded steel cord is made of two or three layers of filaments, mainly developed for trucks and buses.

Representative specifications of the steel cord of the double structure is 3 + 6, 3 + 9, 3 + 9 + 15 steel cord, of which the 3 + 9 steel cord structure in more detail, first located in the inner layer (內層) The core, which is a filament, consists of three filaments twisted in a predetermined direction, and the outer layer surrounding the core has nine filaments in close contact with the core layer, and a single filament that surrounds the outer layer. There may additionally be an inspiral wrap.

Here, the three filaments constituting the inner layer are twisted with each other, and the outer layer is stranded so that the inner layer and the filament diameter and twist direction are the same, but the twist length is different, and the spiral wrap is twisted in the opposite direction to the twist direction of the outer layer. do.

However, since the steel cord has to go through the three-step process to spiral wrap process when stranded wire processing, the unit cost of the steel cord is expensive and there is almost no gap between the filament of the outer layer and the inner layer when cutting the cross section of the steel cord. Rubber penetration of the rubber cord is difficult to penetrate, and when water or salt penetrates, the voids between the filaments that do not penetrate the rubber become their moving paths, which promotes corrosion of the steel cord by repeated bending of the tire. In the end, there was a big problem that the durability of the tire is poor.

There have been several attempts to remedy this problem.

Japanese Patent Application Laid-open No. Hei 7-109685 proposed a steel cord having a structure of 3 + 8. The steel cord removes one of the nine outer layers to form a gap, and then turns the outer layer by changing the twist lengths of the three inner layers and the eight outer layers. This gap was proposed to improve the rubber permeability.

In addition, Japanese Patent Application Laid-open No. Hei 2-306801 discloses a method of improving rubber permeability by changing the inner diameter of three inner layers and eight outer layers (or nine) and making the same twist direction again. He also proposed a method of improving rubber penetration by giving preform deformation to three inner layers.

However, in view of the above inventions proposed so far, the method of changing the wire diameter or twist length of three inner layers and eight outer layers as a method for improving rubber permeability is a fatigue phenomenon due to the wear phenomenon caused by the point contact of the steel wires constituting the steel cord. In addition, there is a disadvantage in that the tire durability is lowered, and when the preform is applied to the three inner layers, since the deformation force is applied to the steel wire, this also has the disadvantage that the tire durability is reduced.

In order to prevent such a decrease in durability, if the twist direction and the twist length of the three inner layers and the eight outer layers are the same, the steel cord may be moved due to a core migration phenomenon in which the three inner layers (core) move in the outer eight layers. Has the disadvantage of not being able to maintain a stable twisted structure when embedded in a tire.

The present invention is to solve the problems described above and at the same time to provide a steel cord that can maintain a stable twist structure by improving the durability and preventing the core movement while maintaining the rubber permeability compared to the conventional steel cord. .

1, the present invention will be described in more detail.

The steel wire used in the present invention is manufactured by heat-treating and brass plating the final high-strength high carbon steel wire having a carbon content of 0.60 to 0.95% so that the wire diameter is 0.2 to 0.38 mm.

As shown in Fig. 1, the steel cord according to the present invention covers the main surface of one steel wire placed on the innermost layer with three inner steel wires twisted together, and covers the main surfaces of the three inner steel wires. It was coated with 8 stranded outer steel wires to have a 1+ (3/8) structure.

In the present invention, the wire diameter of one steel wire located in the innermost layer was 0.2 to 0.8 times as compared to the wire diameter of the steel wire having a 3/8 structure.

In addition, the steel wires of the inner layer and the outer layer forming the 3/8 structure in the present invention preferably have the same wire diameter and have a twist length of 18 mm and a twist direction in the S (clockwise) direction.

In the present invention, when the wire ratio of the innermost layer wire is less than 0.2 times, it is difficult to prevent the core movement because the three strands of the inner layer do not open naturally, and when the inner layer exceeds 0.8 times, the inner three strands are too open to stably twist the inner layer. It cannot be configured.

Since the present invention naturally opened the three strands of the inner layer, rubber permeability was improved, and the point contact with the outer eight strands was reduced, so that the fatigue resistance was improved, thereby improving the durability of the tire.

In addition, the present invention can maintain a stable twist structure because it can reduce the phenomenon that the inner three strands try to move to the twisted portion of the outer eight strands when the steel cord is embedded in the tire (core mobility).

<Example>

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for the purpose of explanation and are not intended to limit the scope of the claims of the present invention.

1) 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 were carried out, and final filament was prepared to wire diameter of 0.20mm and 0.35mm, and 4 inner layers were 1 × 0.20 + 3 × 0.35. 1 × 0.20 + (3/8), consisting of 18mm S (clockwise) twist with structure, 8 strands 0.35mm diameter on the outer surface Table 1 shows the results of producing 0.3 × HT HT steel cord and testing its properties.

2) Comparative Example 1

After heating the wire rod with carbon content of 0.82% by weight and 5.5mm in diameter, heat treatment and brass plating were carried out, and final filament was prepared up to 0.35mm in diameter, and three inner layers were twisted with 9mm length in the S (clockwise) direction. The outer 8 strands were stranded in 18 mm S (clockwise) direction to produce 3 + 8 × 0.35 HT steel cords, and the results of the test were shown in [Table 1].

3) Comparative Example 2

After heating the wire rod with carbon content of 0.82% by weight and 5.5mm in diameter, heat-treat and brass plating, and final drawing to 0.35mm in diameter to prepare the filament.Three inner layers are passed through a roller with serrated protrusions. After preform is applied, 8 layers of outer layer in the direction of S (clock) with 18mm twist length are twisted and twisted in the direction of S (clock) with 18mm twist length to produce 3 + 8 × 0.35 HT (sim preform) steel cord and tested its properties. One result is shown in [Table 1].

[Table 1] Steel Cord Properties

Physical property measurement method used in the present invention is as follows.

* Rubber penetration (cc / min)

: Covered 6mm thick Korean A company rubber on the top and bottom of the manufactured steel cord to make a rubber block of 25.4mm length

  Compressed air was blown into one end of the steel cord for 1 hour to measure the amount of air coming out of the opposite side.

   The greater the amount of air blown out, the lower the rubber penetration.

* Fatigue resistance

 : Rotating Beam Tester (Bekaert Co., Ltd.) tester is used to determine the number of revolutions until fatigue breaks under 150 Kg / mm2 fatigue stress.

   Measured.

Core Migration Stability

 : Manufactured mold which was coated with 6mm thick Korea A company's rubber on the top and bottom of manufactured steel cord and prepared for 25.4mm length rubber block and vulcanized at 160 ℃ × 15 minutes. After removing 8 outermost layers, 3 inner layers were 1 strand. When pulled out of the mold using a thick tensile tester, the pullout deviation between the three strands was measured. The smaller the deviation, the higher the stability of steel cord structure.

The present invention forms a 1 + (3/8) structure by inserting one in the innermost layer of the steel cord having a conventional 3 + 8 structure and the same twist direction and twist length of the inner layer and outer layer, rubber penetration and In addition to improving fatigue resistance and preventing core migration, a stable structure can be maintained even when the tire is embedded.

In the present invention, since the twist direction and the twist length are the same, the present invention can be manufactured in a single twisted pair machine, thereby increasing productivity.

Claims (2)

3 inner layer wires covering the main surface of one steel wire located on the innermost layer and 8 outer layer wires covering the main surface of the three inner steel wires are covered with 1+ ( Steel cord for 3/8) vehicle tires. The steel cord of a vehicle tire according to claim 1, wherein the wire diameter of the innermost steel wire is 0.3 to 0.6 times the wire diameter of the inner and outer steel wire.

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