JPH05339889A - Steel cord - Google Patents

Abstract

PURPOSE:To provide a steel cord improved in the rubber penetration thereinto, thus increase core pull force to prevent core strand's slip-off and rust development. CONSTITUTION:This steel cord is made of two layers consisting of (A) a core strand of three or four core filaments and (B) a side jacket composed of side filaments whose number is six more than the core filaments. In this case, the side filaments (B) and core filaments (A) are opposite to each other in twisting direction, virtually differing in the pitch from each other; besides, the diameter of the side filament is smaller than that of the core filament.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a steel cord,
More particularly, it relates to a reinforcing steel cord used for automobile tires.

[0002]

2. Description of the Related Art Conventionally, a steel cord consisting of two layers of a core strand composed of three core filaments and a side jacket composed of nine side filaments, which is six more than the core filaments, has been used as a steel cord, for example, Japanese Utility Model Publication No. 1-161291. Is known from. This cord is a so-called bundle twisted steel cord created by supplying the above required number of filaments to the twisting machine at once, and this cord is composed of the core and the side filaments having the same twisting direction and the same twisting pitch. , The filament diameters are also the same.

[0003]

Although the steel cord has the advantage that it is manufactured in one step, the filaments of the core and the side are twisted in the same direction and at the same twist pitch, so that the core strand is easily pulled out and the core cord is easily removed during running. There is a problem that it pops out inside or outside the tire. It is also considered that the diameter of the filament constituting the core strand is larger than the filament diameter on the side to prevent the core strand from popping out with the above-mentioned one, but a temporary effect is recognized but it is still insufficient. Yes, the rubber penetration rate is not sufficient.

An object of the present invention is to provide a steel cord in which the core penetration force is increased by increasing the rubber penetration rate in the cord to prevent the core strand from popping out, and at the same time prevent the progress of rust. There is

[0005]

In order to achieve the above object, the present invention provides a core strand composed of three or four core filaments and a side jacket composed of six side filaments more than the core filaments. In the two-layer steel cord, the side filaments and the core filaments have opposite twist directions and substantially different pitches, and the diameter of the side filaments is smaller than the diameter of the core filaments.

[0006]

[Operation] When the twisting directions of the side filament and the core filament are reversed and the pitches are substantially different, the resistance between the core filament and the side filament is increased, and the core strand can be prevented from falling out, and the side filament is prevented. Since the diameter of the core is smaller than the diameter of the core filament, the rubber penetration rate is increased, and core loss of the core strand and progress of rust are prevented.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 1 is a core filament, and three core filaments having a diameter of 0.22 mm are Z-twisted to form a core strand A. 2 is 6 more than the core filament 1, that is, 9 side filaments, which constitute the side jacket B, and the side filament 2 has a diameter of, for example, 0.20 mm and the core filament 1
It is composed of a smaller diameter, arranged substantially concentrically with the core strand A as an S twist as shown in the figure, and finally a small diameter filament 3 is spirally wound on the outermost side to form a steel cord. (3 x 0.22 + 9 x 0.20 +
1). The twist pitch of the core filament 1 and the twist pitch of the side filament 2 are substantially different, for example, the former is 6 mm and the latter is 12 mm, which means that the pitches of the two may be substantially different. ..

In the steel cord of the present invention, the twist pitches of the core filament 1 and the side filament 2 are substantially different, and the core filament 1 and the side filament 2 are different.
The reason why the twisting direction is reversed is to increase the resistance between both filaments and prevent the core from slipping out, but this alone is not sufficient for rubber intrusion. It was smaller than the diameter of filament. In addition, it is not preferable that the core strand A is composed of three or four core filaments 1 if the core filament A is 5 or more because the central space becomes large and the amount of air permeation is large and rust is generated. On the other hand, when the number is two, the core strand A is
Shape becomes worse.

Further, the number of the side filaments 2 is increased by 6 more than the number of the core filaments 1 to configure the side jacket B. When the number of the side filaments 2 is more than 6, the interval between the filaments becomes narrow. Rubber invasion gets worse. Further, if the number is 6 or less, the side filaments may be positioned so as to be rigid with respect to the core strand A, and the cross section becomes irregular in the length direction of the cord, and the fatigue property is deteriorated.

FIG. 2 shows a steel cord composed of a core strand A composed of four core filaments 1 and a side jacket B composed of six side filaments 2. 1 for each core and side filament
It is composed of many books (4 x 0.22 + 10 x 0.20 +
1). What is shown in FIGS. 3, 4 and 5 is each comparative example, and the configuration thereof is as shown in Table 1.

Table 1 shows the test results of the examples of the steel cord of the present invention together with comparative examples. Table 1 shows the steel cord of the example of the present invention and the steel cord of the comparative example, and the bead reinforcement portion (15 / inch) of the 10.00R20 14PR tire.
It is the test result when the mileage is 60.000km.

[0012]

[Table 1]

Rubber invasion: After embedding a steel cord of 100 mm in rubber and heating it, the cord is taken out to remove the side filaments (three core filaments are provided), and the rubber adhesion amount of the three core filaments is expressed in%. ..
(The higher the number, the more rubber is attached and the better.) Core pull-out force ... Steel cord 100mm embedded length 20
embedded in rubber to vulcanize to 3 mm and core filament 3
The book is exposed and the core pull-out force is measured with a Tensilon tensile tester. (The higher the number, the more difficult the core is to fall out, and the better.) Fatigue life: The number of times until the cord breaks when fatigued by applying an initial load of 100 N to the cord using a 3-roll fatigue tester with a roll diameter of 1 inch is shown in Comparative Example 1. Expressed as 100. (The higher the number, the longer the life is.) Rubber intrusion: Take out the cord from the tire and evaluate in the same manner as above. Core pulling force: The tire is cut so that the cord embedding length is 15 mm, and the same evaluation as above is performed. Rust occurrence score: Take out the cord from the tire, disassemble the cord, and evaluate the rust condition on a five-grade scale. (The larger the number, the more the rust is generated and the worse) According to the above test results, the product of Example 1 of the present invention is
Comparative Example 1 in both cord characteristics and tire characteristics
It was confirmed that the core-releasing force was large, the rubber penetration rate was large, and the occurrence of rust was small in comparison with those of Nos.

[0014]

The steel cord of the present invention is a steel cord comprising two layers of a core strand composed of three or four core filaments and a side jacket composed of six side filaments more than the core filaments. The filament and core filaments have opposite twisting directions and substantially different pitches, and the diameter of the side filaments is smaller than the diameter of the core filaments, so the rubber penetration rate improves and the core removal force increases, and the running It is excellent in that it does not jump out to the inner surface or the outer surface of the inside tire, prevents the progress of rust, and solves the conventional problems.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a first embodiment of a steel cord according to the present invention.

FIG. 2 is an explanatory view showing Embodiment 2 of the steel cord according to the present invention.

FIG. 3 is an explanatory diagram showing Comparative Example 1.

FIG. 4 is an explanatory diagram showing Comparative Example 2.

FIG. 5 is an explanatory diagram showing Comparative Example 3.

[Explanation of symbols]

 1 core filament 2 side filament 3 spiral filament A core strand B side jacket

Claims (1)

[Claims] 1. A steel cord comprising two layers of a core strand composed of three or four core filaments and a side jacket composed of six more side filaments than the core filaments, wherein the side filaments and the core filaments are twisted. , But the pitch is substantially different, and the diameter of the side filament is smaller than the diameter of the core filament.