JPH0742089A - Steel cord for reinforcing rubber - Google Patents

Abstract

PURPOSE:To provide a steel cord for reinforcing a rubber, enhanced in tensile strength, fatigue resistance and rubber permeability and improved in durability by forming a core wire bundle in a suitable wave shape, equalizing the built-in length and elongation of each element wire, and forming proper distances between the element wires. CONSTITUTION:In a rubber-reinforcing steel cord provided with a core wire bundle 1a formed by arranging two element wires 1 in parallel and a side wire bundle 2b formed by spirally winding two or three parallel element wires 2 on the core wire bundle 1a, the side bundle 2b is spirally arranged in a winding pitch Pb represented by an equality: 45d<Pb<65d. The core wire bundle la is arranged in a shape waved in a waving pitch Pa having the relation of an inequality: (1/15)Pb<Pa<(1/3)Pb with the winding pitch Pb, and the length of the built-in wire in the core wire bundle 1a is approximately the same as that of the element wire 2 in the side wire bundle 2b. Distances are formed between the element wires. The waving height (h) of the core bundle 1a formed in the wave shape is 2.0d<h<5.0d.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-reinforcing steel cord which is applied as a rubber-reinforcing material for various automobile tires, conveyor belts and the like, and is particularly suitable for a belt layer of a tire.

[0002]

2. Description of the Related Art Conventionally, in various automobile tires,
The steel cord for rubber reinforcement used in the belt layer is generally a steel cord with a 1 × n structure formed by twisting 3 to 5 strands. This steel cord has a cord shape. Since the holding property, rubber permeability, and reliability are poor, a core bundle formed by making two strands substantially parallel to each other, and a side formed by spirally winding two or three strands around this core bundle A steel cord having a 2 + 2 structure or a 2 + 3 structure, which has a wire bundle and has improved cord shape retention and rubber permeability, has been developed and proposed (Japanese Patent Publication No. 2940/1990).
No. 8, Japanese Patent Publication No. 4-41081, etc.).

[0003]

In the conventional steel cord for rubber reinforcement, the 2 + 2 structure and the 2+ structure as described above are used.
The three-structure steel cord has a structure that enhances the cord shape retention and rubber permeability, but the lengths of the incorporated core wire and side wire bundles are different, and the repeated load (tensile tension) , Compression) becomes non-uniform, and tensile stress concentrates on the wires of the core bundle, causing early disconnection and lowering of tensile strength. There are problems such as partial contact and contributing to local scratches and corrosion.

The present invention was developed in order to address the above-mentioned problems. The object of the present invention is to make the core wire bundle into an appropriate wave shape and to incorporate the length and elongation of each wire. The present invention provides a rubber-reinforcing steel cord in which the tensile strength, fatigue strength and rubber permeability are enhanced by uniformly forming the wire and forming an appropriate gap between the wires.

[0005]

According to the present invention, a core wire bundle is formed by parallelizing two strands of wire, and two or three strands of wire are spirally wound around the core bundle. In a steel cord for rubber reinforcement having a side wire bundle, the side wire bundle has the winding pitch Pb of 45d <Pb with respect to the wire diameter d.
The core wire bundle is formed in the range of <65d and the corrugated pitch Pa is (1) with respect to the winding pitch Pb.
/ 15) Pb <Pa <(1/3) Pb is formed into a corrugated shape so that the built-in strand length of the core bundle is almost the same as that of the side bundle and By forming a gap in the core wire and the side wire bundle, the lengths and elongations of the incorporated wires are made approximately equal, and a suitable gap is formed between the wires to partially concentrate stress on the wires, disconnection, and tensile strength of the cord. In addition to preventing the deterioration of the wire, the rubber permeability and reliability are improved to prevent the wire from being scratched and corroded.

Further, the corrugated core wire bundle is formed with a corrugated height h in the range of 2.0d <h <5.0d to equalize the incorporated strand length and elongation of each strand, The gap between the wires is formed and reliability is further improved.

[0007]

[Operation] A core wire bundle formed by parallelizing two strands of wire,
In a steel cord for rubber reinforcement having a side wire bundle formed by spirally winding two or three strands of wire around a core wire bundle, the side wire bundle has a winding pitch Pb of 45d <Pb with respect to the wire diameter d. By forming the spiral shape in the range of <65d, the cord shape retaining property is improved together with the fatigue property, and the core wire bundle has this corrugated pitch Pa with (1/15) Pb <Pa <(1 / 3) Pb
The corrugated shape formed by corrugating in the range of and the corrugated height h of this core bundle is formed in the range of 2.0d <h <5.0d, thereby incorporating the core and side bundles By making the length and elongation almost equal and forming an appropriate gap between the strands, stress concentration on some strands, disconnection, and cord strength reduction can be prevented, and rubber penetration and reliability can be improved. Abrasion of the wire,
Effectively prevents corrosion and enhances durability.

[0008]

1 to 3 show an embodiment of the present invention.
In the figure, 1 is an element wire forming a core wire bundle 1a, 2 is an element wire forming a side wire bundle 2b, d is an element wire diameter (diameter) of the element wires 1 and 2, Pa
Is a corrugated pitch of the core wire bundle 1a, h is a corrugation height of the core wire bundle 1a, Pb is a winding pitch of the side wire bundle 2b, α is a gap formed between the wires 1 and 2, and the present invention is 2 A core wire bundle 1a formed by parallelizing the strands 1 of a book, and a core wire bundle 1a
In the steel cord for rubber reinforcement having the side wire bundle 2b formed by spirally winding two or three wire strands 2 in parallel with each other, the side wire bundle 2b has the winding pitch Pb of 45d <with respect to the wire diameter d. The core wire bundle 1a has a spiral shape formed in the range of Pb <65d, and the core wire bundle 1a is (1/15) Pb <Pa <(1 /
3) The corrugated shape is formed by corrugating in the range of Pb so that the built-in strand length of the core wire bundle 1a is almost the same as that of the strand wire 2 of the side wire bundle 2b and the gap α is formed between the strand wires 1 and 2. It is a formed steel cord for rubber reinforcement.

Further, in the above-mentioned rubber-reinforcing steel cord, the corrugated core wire 1a has a corrugated height h in the range of 2.0d <h <5.0d. It has become a steel cord.

More specifically, the strands 1 and 2 forming the core bundle 1a and the side bundle 2b preferably have a strand diameter (diameter) d of 0.15 to 0.35 mm and a tensile strength of 2.
An element wire in the range of 50 to 400 kgf / mm is used, and the core wire bundle 1a is formed by making the two element wires 1 substantially parallel to each other without almost twisting each other, and an appropriate crimping device ( Corrugation (crimping in at least one plane) is performed in advance by (not shown) to form a corrugated shape with a corrugated pitch Pa and a corrugated height h.
a is (1/1) with respect to the winding pitch Pb of the side wire bundle 2b.
5) The corrugated height h is formed in the range of Pb <Pa <(1/3) Pb and in the range of 2.0d <h <5.0d (see FIGS. 1B and 3). In addition, the side wire bundle 2b is made by twisting two (three in the figure) or three (not shown) strands 2 almost in parallel with each other and winding them around the core wire bundle 1a in a spiral shape with a pitch Pb. It is formed by winding, and the winding pitch Pb of the side wire bundle 2b is 45d <P with respect to the wire diameter d.
It is formed in the range of b <65d (see FIG. 1). The rubber-reinforcing steel cord is formed by forming a bundle of core wires by attaching a crimping device (not shown) to a conventionally known twisting machine 2
The strands 1 of a book are corrugated in advance before being twisted, so that they can be efficiently manufactured in one step.

The above-mentioned steel cord for rubber reinforcement has a core wire bundle 1a formed by parallelizing two strands 1 and two or three strands 2 parallel to the core wire bundle 1a in a spiral shape. In the steel cord having the side wire bundle 2b formed by winding, the side wire bundle 2b is formed in a spiral shape in which the winding pitch Pb is formed in the range of 45d <Pb <65d with respect to the wire diameter d, and the bending strength and The tensile strength is moderately secured without excessive increase or decrease, and the cord shape retention is secured to effectively improve the fatigue characteristics.
Is (1/15) Pb <Pa <(1/3) Pb with respect to the winding pitch Pb of the side wire bundle 2b.
Is formed into a corrugated shape in the range of, and due to the appropriate corrugated shape of the core wire bundle 1a as described above, the built-in length of each wire 1 of the core wire bundle 1a is equal to that of each wire 2 of the side wire bundle 2b. The length is almost the same as the built-in length and the elongation is almost the same.
The repeated load applied to the cord is evenly received by all the wires 1 and 2, so that stress concentration, disconnection, etc. are effectively prevented. Further, as shown in the figure, a proper gap α is formed between each wire 1 of the core wire bundle 1a and each wire 2 of the side wire bundle 2b, and the corrugated wire bundle 1a is corrugated with respect to the winding pitch Pb of the side wire bundle 2b. By forming the pitch Pa to be appropriately short as described above, the gap α is appropriately formed as shown in FIGS. 1 and 2, the conventional partial close contact portion is eliminated, and the gap forming performance,
Reliability is enhanced and excellent rubber permeability is obtained. Therefore, the durability is effectively enhanced, such that damage and corrosion due to friction are significantly reduced.

Further, in the above-mentioned core wire bundle 1a, by forming the corrugation height h in the range of 2.0d <h <5.0d, the strands 1 and 2 of the core wire bundle 1a and the side wire bundle 2b are formed. The assembling length and the elongation are further equalized, and the gap α between the strands 1 and 2 is optimized so that the above-described action, effect, and reliability are further enhanced.

Each sample shown in Table 1 uses a wire having a wire diameter of 0.25 mm and is formed by twisting four wires 1 ×.
A steel cord having four structures was manufactured to be a conventional example 1, and a core wire bundle formed by making two element wires substantially parallel to each other and a side wire bundle formed by spirally winding two element wires around the core wire bundle were provided. A conventional steel cord having a 2 + 2 structure was manufactured as Conventional Example 2, and the winding pitch of the side wire bundle was changed, and the core wire bundle was corrugated, and the corrugated pitch and height were changed to obtain a large number of 2 + 2. Steel cords having a structure are manufactured, and representative examples of these are Comparative Examples 1 to 4 and Example 1.
.About.3, the gap between the strands of each cord, the tensile strength, the fatigue property, the air permeation, etc. were measured, and each of these measured values was indexed together with a real number to obtain the evaluation as shown.

As is clear from the evaluation of Table 1, Examples 1 to 3 (steel cords having a 2 + 2 structure) having the structure of the present invention were formed by corrugating the conventional example 1 having a 1 × 4 structure and the core wire bundle. Compared with the conventional example 2 of the conventional 2 + 2 structure which is not provided, it is excellent in the formation of the gap between the strands, the tensile strength, the fatigue property and the air permeability (rubber permeability). Further, as shown in Comparative Examples 1 and 4, the winding pitch Pb of the side wire bundle is set to 45d.
If it is less than or equal to or more than 65d, the bending strength and tensile strength of the cord are excessively increased or decreased, and the formation performance of the gap between the strands,
The tensile strength is reduced, and as shown in Comparative Example 2,
When the corrugation pitch Pa of the core bundle is set to 1/3 Pb or more, air permeation and the performance of forming a gap between the strands are deteriorated as shown in the display, and further, as shown in Comparative Example 3, the core bundle is corrugated. When the height h is 5.0d or more, the tensile strength is remarkably reduced. Although only a representative sample is shown in Table 1, a larger number of 2
The steel cords of +2 structure are evaluated to confirm the above-mentioned actions and effects, and the steel cords of 2 + 3 structure are also manufactured in large numbers and evaluated to confirm their actions and effects (specifically (Example omitted).

[0015]

[Table 1]

[0016]

According to the present invention, as described above, the core wire bundle is formed by bundling two wire wires in parallel, and two or three wire wires are wound in parallel with the wire core wire. In a steel cord for rubber reinforcement having a side wire bundle, the side wire bundle has a winding pitch Pb of 45d <Pb <6 with respect to the wire diameter d.
The spiral shape formed in the range of 5d enhances the fatigue property and the retaining property of the cord shape, and the core wire bundle has the corrugated pitch Pa of (1/15) Pb <Pa <(with respect to the winding pitch Pb. 1/3) Pb is formed in a corrugated shape, and the corrugation height h of this core bundle is formed in the range of 2.0d <h <5.0d. Assembling the strands of the wire bundle to make the strand lengths and elongations almost equal and to form a suitable gap between the strands to prevent stress concentration in some strands, disconnection, and reduction in cord strength. The penetrability and reliability are enhanced to effectively prevent abrasion and corrosion of the wire, and the durability and reliability are remarkably improved.

[Brief description of drawings]

FIG. 1 is a side view (A) showing an embodiment of the present invention and a plan view / partial sectional view thereof (B).

FIG. 2 is an enlarged sectional view of the sectional view shown in FIG.

FIG. 3 is an enlarged plan view of the core wire bundle shown in FIG.

[Explanation of symbols]

 1 strand (core bundle) 1a core bundle 2 strand (side bundle) 2b side bundle d diameter (strand) Pa corrugated pitch (core bundle) Pb winding pitch (side bundle) h corrugation height α gap (strand) (Between lines)

Claims (2)

[Claims] 1. A rubber reinforcing member comprising: a core wire bundle formed by parallelizing two strands of wire; and a side wire bundle formed by spirally winding two or three strands of wire around the core wire bundle. In the steel cord, the side wire bundle has a spiral shape in which the winding pitch Pb is formed in a range of 45d <Pb <65d with respect to the wire diameter d, and the core wire bundle has the corrugated pitch Pb.
a is (1/15) Pb with respect to the winding pitch Pb
<Pa <(1/3) Pb is formed in a wavy shape so that the built-in strands of the core wire bundle have almost the same length as the strands of the side wire bundle, and a gap is formed between the strands. Steel cord for rubber reinforcement characterized by 2. The steel cord for rubber reinforcement according to claim 1, wherein the corrugated core wire bundle has a corrugated height h of 2.0d <h <5.0d. Steel cord for rubber reinforcement.