JP2596816Y2 - Steel cord for rubber article reinforcement - Google Patents

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.

[0002]

BACKGROUND ART Rubber articles reinforced with steel cords,
For example, regarding tires and the like, weight reduction and low rolling resistance have been desired in response to recent environmental problems and higher energy efficiency. In particular, for fuel-efficient tires, a steel cord that is lighter and stronger is required.

Hitherto, various proposals have been made for the structure of a steel cord (JP-A-59-1790, JP-A-61-1552, etc.). However, these are intended to improve the durability of the rubber article by increasing the rubber permeability to the steel cord, and the strength of the steel cord has hardly been studied.

Further, Japanese Patent Application Laid-Open No. 2-154086 discusses in detail the effect of the twist pitch on a pneumatic radial tire reinforced with a steel cord. However, similarly to the above, it is intended to improve the durability by increasing the rubber permeability to the steel cord, and the correlation between the strength of the steel cord and the twist pitch has not been studied.

[0005]

Generally, if the ratio Pc / Ps of the twist pitch Pc of the core filament in the core strand to the twist pitch Ps of the sheath filament is increased, the twist loss of the core filament increases. is there. Conversely, when Pc / Ps is reduced, when a tensile stress is applied in the longitudinal direction of the cord, the core filament in the core strand has a higher twist angle than the other filaments, causing premature breakage and loss of filament strength. However, there is a problem that is increased.

The present invention has been made in view of the above-mentioned problems of the prior art, and has an object to reinforce rubber articles such as pneumatic tires and industrial belts. Is to provide a steel cord.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found a novel structure that increases the strength of a steel cord, and have completed the present invention.

That is, according to the present invention, a plurality of core filaments and sheath filaments having substantially the same diameter are twisted to form a core strand and a sheath strand, respectively, and a plurality of sheath strands are twisted around the core strand. In a cord having a twist structure, in which the twist direction of the core strand and the cord is the same, the twist pitch of the core filament and the sheath filament in the core strand is Pc and Ps, respectively, and the twist pitch of the cord (cable pitch) ) Is Pk, the ratio is 0.5 <Pc / Ps <1.0 2.6 ≦ Pk / Pc ≦ 6.0, preferably 0.54 <Pc / Ps <0.90 3.0 ≦ Pk /Pc≦6.0 is a steel cord for reinforcing rubber articles.

It is desired that the twist pitch ratio between the core filament and the sheath filament in the sheath strand is equal to the twist pitch ratio between the core filament and the sheath filament in the core strand.

As a reinforcing material, in order to secure the strength of the composite and reduce its weight, the carbon content must be 0.80 to 0.85 watts.
Steel cords in the range of t% are advantageously suitable.

[0011]

The reason why the twist pitch ratio between the core filament and the sheath filament in the core strand is set to be 0.5 <Pc / Ps <1.0 is that when the value of the Pc / Ps ratio becomes 0.5 or less. ,
Since the twist loss of the core filament is increased, the strength of the steel cord is reduced, and the strength desirable as a reinforcing material cannot be obtained. Conversely, when the value of the Pc / Ps ratio is 1.0 or more, the twist loss of the core filament decreases,
When a tensile stress is applied in the longitudinal direction of the cord, the core filament in the core strand breaks prematurely because the twist angle is higher than other filaments, resulting in a decrease in cord strength.

Next, the twist pitch ratio between the core filament and the cord in the core strand is set to 2.6 ≦ Pk / Pc ≦
The reason for setting the value 6.0 is that if the value of the Pk / Pc ratio is smaller than 2.6, the twist loss of the cord increases, and the cord strength decreases. Further, when the value of the Pk / Pc ratio is larger than 6.0, the twist angle of the cord (cable twist angle) increases, so that the twist pitch of the core filament in the core strand is shorter than the twist pitch of the sheath filament. The effect is reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments and comparative examples with reference to the drawings, but the present invention is not limited to these embodiments. (Examples 1 to 4, Comparative Examples 1 to 3) Twist pitch, twist pitch ratio (Pc / Ps, P
k / Pc), the carbon content, the core filament twist angle, and the results of measuring the cord strength of each of the trial steel cords with different cord twist angles are shown.

[0014] The cord strength was measured based on the measuring method of "cutting load" of 6.4 specified in "Steel tire cord test method" of JIS G3510.

[0015]

[Table 1]

From the results in Table 1 above, the following has been found.
Here, the steel cords of the comparative example and the example shown in Table 1 had the same filament arrangement number of 7 × (3+
9) having +1 but Comparative Examples 1 and 2 and Examples 1-4
1 has the structure shown in FIG. 1, and Comparative Example 3 has the structure shown in FIG.

In Example 1, the twist pitch of the core filament was made longer than that of Comparative Example 1, whereby the twist pitch ratio (Pc / Ps) between the core filament and the sheath filament was increased, and the cord strength was accordingly increased. Is increasing. In Example 2, the twist pitch of the core filament was further increased, and the cord strength was increased as described above. In Example 3, although the twist pitch of the core filament was further increased than in Example 2, the cord strength was better than that of Comparative Example 1, but was lower than that of Example 2. Example 4 has the same twist pitch configuration as Example 2, and has a carbon content of 0.82 wt%.
This has led to a significant increase in code strength.

Comparative Example 2 has the same twist pitch configuration as in Example 1, but the twist pitch ratio (Pk / Pc) between the cord and the core filament is 6.50 (out of the scope of the present invention).
And because of the large, shows low code strength. In Comparative Example 3, the twist pitch ratio (Pc / Ps) between the core filament and the sheath filament was 1.0 (outside the scope of the present invention). However, since the arrangement of the filaments was different from those of the other Examples and Comparative Examples. , A value equivalent to the code strength of the third embodiment.

[0019]

[Effects of the Invention] Since the present invention is configured as described above, the strength of the steel cord can be improved, and the performance of a rubber article using the steel cord as a reinforcing material can be greatly improved. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a steel cord.

FIG. 2 is a sectional view of a steel cord.

FIGS. 3A, 3B, and 3C are partial front views showing corrugated surfaces of a core filament, a sheath filament, and a sheath strand, respectively.

FIG. 4 is an exploded perspective view of a steel cord.

[Explanation of symbols]

 1 Cord 2 Core strand 3, 3a Core filament 4, 4a Sheath filament 5 Sheath strand 6 Spiral filament

Claims (4)

(57) [Scope of request for utility model registration] 1. A plurality of core filaments (3, 3a) and sheath filaments (4, 4a) having substantially the same diameter.
Having a multi-strand structure in which a core strand (2) and a sheath strand (5) are formed by twisting each other, and a plurality of sheath strands (5) are twisted around the core strand (2). In the cord (1) in which the twist direction of the core strand (2) and the cord (1) is the same, the core strand (2)
When the twist pitch of the core filament (3) and the sheath filament (4) is Pc and Ps, respectively, and the twist pitch of the cord (1) is Pk, the following expressions (I) and (II) 0.5 < Steel cord for reinforcing rubber articles satisfying Pc / Ps <1.0 (I) 2.6 ≦ Pk / Pc ≦ 6.0 (II). 2. The ratio Pc / Ps of the twist pitch Pc of the core filament (3) in the core strand (2) to the twist pitch Ps of the sheath filament (4) is 0.54 ≦ Pc / Ps ≦ 0.90. The steel cord for reinforcing a rubber article according to claim 1. 3. The ratio of the twist pitch Pc of the core filament (3) in the core strand (2) to the twist pitch Pk of the cord (1) is represented by 3.0 ≦ Pk / Pc ≦ 6.0. Item 3. A steel cord for reinforcing rubber articles according to item 1 or 2. 4. A steel cord having a carbon content of 0.8.
The steel cord for reinforcing rubber articles according to any one of claims 1 to 3, wherein high carbon steel in a range of 0 to 0.85 wt% is used.