JPH06330486A - Steel cord for reinforcing rubber, and steel radial tire - Google Patents

Abstract

PURPOSE:To enhance the performance for forming gap between wire cords, permeability of rubber, reliability and durability, property for keeping shape of cord, vertical elastic coefficient and stiffness of steel cord by forming the diameter of at least one of wire so as to have thicker diameter and have composite spiral shape, compared with other wires. CONSTITUTION:In a steel cord for reinforcing rubber, formed by twisting 3 or 5 wires together, at least one wire 1 is formed in thicker diameter than other raw materials 2 and 3 and simultaneously formed into composite spiral shape (a) and (b) by carrying out preforming (pitch: Pa and waving height: Ha) different in pitch or waving height and twisting (pitch: P; twisting height: H) and space S is formed between the wire 1 and other wires 2 and 3 and the diameter (d1) of the wire 1 formed in composite spiral shape (a) and (b) is constituted so as to satisfy the formula (d1)= (1.02-1.04)X(d2) based on diameter (d2) of other wires 2 and 3. The twisting angle beta of this steel cord is constituted so as to satisfy the formula based on number N of the wire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord and a steel radial tire for rubber reinforcement embedded in an automobile tire, a conveyor belt or the like, and particularly suitable as a rubber reinforcement material for a belt portion of a steel radial tire. Is.

[0002]

2. Description of the Related Art A steel radial tire for an automobile will be described. The belt portion has a 1 × 3 structure in which 3 to 5 strands (filament) are twisted together, and a 1 × 3 structure is used.
A steel cord of 4 structure or 1 × 5 structure is generally used.

In recent years, the trend toward higher operating speeds has gradually increased due to the completion of paved roads and the accompanying improvement in transportation efficiency, and the demand for flattening tires and improving high-speed durability is gradually increasing. High elasticity is needed. In addition, due to this increase in elasticity, it becomes more susceptible to external damage due to running stones, etc., and water penetrates into the belt from this scratch, which causes cord corrosion and deteriorates rubber adhesion, resulting in repeated dynamic compression. Defects such as early breaking of the steel cord due to stress have come to the surface.

Conventionally, in the 1 × n structure steel cord as described above, an open type steel cord in which a gap is formed between the strands (filaments) in order to enhance the rubber permeability (for example, Japanese Patent Publication No. 63-32916). Or 2+
2 types of open type steel cord (eg
No. 29408), a rubber-reinforcing steel cord in which at least one of the strands is formed in a composite spiral shape and a gap is formed between the strand and other strands has been developed and proposed.

[0005]

Among the conventional steel cords for rubber reinforcement, the open type steel cord as described above has a structure in which the elongation is relatively large under a low load and is easily deformed. When it is embedded and vulcanized, the gap formed between the strands is closed, and the cord shape in the longitudinal direction tends to vary, resulting in reduced rubber permeability and tire uniformity (uniformity, tire balance). It is a factor. Further, as described above, the rubber-reinforcing steel cord in which at least one of the strands is formed in a composite spiral shape,
Although the forming performance of the gap between the strands and the shape retention of the cord are improved, the rubber penetration and the tire uniform property are improved,
This composite spiral wire is twisted in the cord longer than the other wires, and there is a problem that the longitudinal elastic modulus and rigidity of the steel cord are lowered.

The present invention was developed in order to address the above-mentioned problems. The object of the present invention is to make at least one of the wire strands have a moderately large diameter with respect to other wire strands. In addition, it is made into a composite spiral shape, and the performance of forming the gap between the strands, the shape retention of the cord as well as the longitudinal elastic modulus and rigidity of the steel cord are increased, and the rubber reinforcement that improves the rubber permeability, reliability and tire uniform property as well as durability. To provide steel cords and steel radial tires for.

[0007]

SUMMARY OF THE INVENTION The present invention is a rubber-reinforced steel cord formed by twisting three to five strands, wherein at least one strand is slightly thicker than other strands. As a steel cord for rubber reinforcement, which has a diameter, and is formed into a compound spiral shape by forming and twisting with different pitches or corrugations and forming gaps between other strands. In addition to the forming performance of the gap between them, the shape retention of the cord, the longitudinal elastic modulus and rigidity of the steel cord are enhanced.

Further, the diameter d1 of the wire formed in the above-mentioned composite spiral shape is expressed by the following equation d1 = the diameter d2 of the other wires.
Since the steel cord has a large diameter that satisfies (1.02 to 1.04) × d2, the longitudinal elastic modulus and rigidity of the steel cord are appropriately increased. Further, the twist angle β of the steel cord is expressed by the following equation with respect to the number N of strands.

[0009]

[Equation 1]

The twisted structure satisfying the above conditions further improves the shape retention and reliability of the steel cord.

Further, in each of the above-mentioned steel cords for rubber reinforcement, as a steel radial tire having a rubber reinforcement layer formed by embedding the steel cord in the belt portion of the tire, rubber reinforcement performance, reliability and tire uniform property are obtained. Along with that, it effectively increases durability.

[0012]

In a steel cord for rubber reinforcement formed by twisting three to five strands, at least one strand of the strands is formed by twisting with a pitch or another corrugation height. And form a suitable gap between the strands to increase the rubber permeability due to the shape retention of the cord, and to make the strand a little thicker than other strands, the longitudinal elastic modulus of the steel cord and The rigidity is prevented from decreasing and the rigidity is appropriately increased.

Further, the diameter d1 of the wire formed in the above-mentioned compound spiral is expressed by the following equation d1 = the diameter d2 of the other wire.
Since the steel cord has a large diameter that satisfies (1.02 to 1.04) × d2, the longitudinal elastic modulus and rigidity of the steel cord are appropriately increased. In addition, the twist angle β of the steel cord is expressed by the following equation with respect to the number N of strands.

[0014]

[Equation 1]

With the twisted structure satisfying the above condition, the shape retention of the steel cord is further effectively enhanced.

Further, in each of the above-mentioned steel cords for rubber reinforcement, as a steel radial tire having a rubber reinforcement layer formed by embedding the steel cord in the belt portion of the tire, rubber reinforcement performance, reliability and tire uniform property are obtained. Along with that, it effectively increases durability.

[0017]

1 and 2 show an embodiment of a steel cord for rubber reinforcement of the present invention, and FIGS. 3 and 4 show an embodiment of a manufacturing apparatus thereof. In FIGS. 1 and 2, reference numerals 1, 2 and 3 are filaments having a surface treatment such as brass plating (filament), d1 is a diameter of the filament 1, d2 is a diameter of the filaments 2 and 3, and β is a steel cord. Twist angle, Pa is the pitch of the strands of wire 1, P is the twisting pitch of the steel cords, Ha is the height of the strands of wire 1, H is the twisting height of the steel cords, a, b
1 and 2 are different corrugations formed on the wire 1, S is a gap formed between the wire 1 and the wires 2 and 3, and 10 is a steel cord for rubber reinforcement of the present invention, which is shown in FIGS. In the embodiment, in a rubber-reinforcing steel cord formed by twisting three strands 1, 2 and 3, at least one strand 1 has a slightly larger diameter than the other strands 2 and 3. With
Other strands 2 are formed into composite spirals a and b by means of pitching or patterning with different corrugation heights (Pitch Pa, corrugation height Ha) and twisting (Pitch P, twisting height H). , 3 to form a rubber reinforcing steel cord 10.

Further, the rubber reinforcing steel cord 1 described above.
At 0, the diameter d1 of the wire 1 formed into a composite spiral shape
For the diameters d2 of the other wires 2 and 3, the following equation d1 = (1.
The steel cord 10 for rubber reinforcement is characterized by having a large diameter satisfying the range of 02 to 1.04) × d 2. Further, in the above-mentioned steel cord 10 for rubber reinforcement, the twist angle β of the steel cord 10 is the number N of strands.
On the other hand,

[0019]

[Equation 1]

The steel cord for rubber reinforcement 10 is characterized by having a twisted structure satisfying the above conditions.

Further, each of the above-mentioned steel cords 10 for rubber reinforcement is provided with a rubber reinforcement layer formed by embedding the steel cord 10 in the belt portion of the tire. (Not shown). The steel cord 10 for rubber reinforcement of the present invention
Is a 1 × 4 structure or a 1 × 3 structure in addition to the 1 × 3 structure shown in the figure.
It is applied as a steel cord having five structures, and in the case of a 1 × 4 structure or a 1 × 5 structure, it is possible to configure a plurality of strands 1 formed in a composite spiral shape as needed.

The rubber reinforcing steel cord 10 is
It is manufactured by the manufacturing apparatus as shown in FIGS. The manufacturing apparatus shown in the drawing has a rotary die attaching mechanism 12 including a rotary die attaching body 12a whose rotation is controlled by a motor 19 and a plurality of die attaching pins 12b arranged in the rotary die attaching body 12a. A wire rod (diameter d1) 1 and a wire rod (diameter d2) 2 having a tensile strength of 250 to 400 kgf / mm ² are provided from each bobbin 11 by including an arc-shaped rotation guide that is controlled to rotate in the opposite direction with respect to the mold body 12a. , A wire (diameter d2) 3 is respectively fed out, and the wire 1 is desired to be molded by a mold pin 12b in a rotary mold body 12a whose rotation is controlled in the arrow direction. Rotating mold attached body 1
The molding pitch Pa is adjusted by the rotation speed of 2a. Next, the other strands 2 and 3 are aligned with the strands 1 after being molded and pass through the hollow shaft 13a, and the guide wheel 14a is controlled to rotate in the opposite direction as indicated by the arrow, and the arc-shaped rotation. It is twisted in the opposite direction by the guide 15 and the guide wheel 14b,
The steel cord 10 having the structure shown in FIGS. 1 and 2 is manufactured with high accuracy and high efficiency in a series of steps by being wound on the bobbin 18 via the over twister 16, the leveling roll, the capstan 17, and the like.

The rotary die attaching mechanism 1 shown in FIG.
It is also possible to apply the typed mechanism 12 shown in FIG. Further, an increase in the number of strands is dealt with by adding the bobbin 11, and an increase in the number of typed strands is dealt with by the addition of a die forming mechanism.

In each of the samples shown in the tables, Examples 1 to 3 and Comparative Example 1 are composite spirals formed by twisting strands (one piece) having a large diameter d1 with a pitch or also with different corrugation heights and twisting. Wires (2
Each of the steel cords having a 1 × (1 × d1 + 2 × d2) structure by forming a gap between them and changing the diameter ratio of the strands. Alternatively, 1 × (1 × d2 + 2 × d2) is formed by forming a composite spiral a, b by forming and twisting with different corrugation heights, and forming a gap between the same-diameter strands (two). ) Structure steel cord, the conventional example 1 is a closed cord of 1 × 3 × d2 structure formed by tightly twisting strands (3 pieces) of the same diameter, and the conventional example 2 is a strand of the same diameter (3 This is an open cord having a 1 × 3 × d2 structure in which a gap is formed between the twisted strands by molding the (book), and the specific structure of each of these samples is as shown in Table 1.

Further, each sample was embedded in a rubber pound, the rubber permeability was measured, the elastic modulus and the rigidity coefficient were compared, and the cord elongation was measured, and the evaluations shown in Table 2 were obtained. Furthermore, in the sample shown in Table 3, Example 2
In each of -a to 2-e and Comparative Examples 3-a to 3-c, a single wire having a large diameter d1 is twisted and twisted with a pitch or a corrugation having a different corrugation height as in the second embodiment. To form a composite spiral a, b, with a small diameter d2 (2
This is each steel cord with a different 1 × (1 × d1 + 2 × d2) structure by forming a gap between the cord and the cord and changing the twist angle β of the cord, and the strength utilization rate (%) of each cord Also, the evaluation as shown was obtained by the twisted shape.

[0026]

[Table 1]

In Table 1, d1 is the diameter of the large-diameter wire, d2 is the diameter of the small-diameter wire, d1 / d2 is the wire diameter ratio, Pa is the patterning pitch of the large-diameter wire, P is the twisting pitch of the cord, β is the twist angle of the cord. Further, the longitudinal elastic modulus ratio in Table 2 is shown as an index with 100 in the case of the same strand diameter, and the rigidity coefficient is
(D1 ⁴ + 2d2 ⁴ ) / 3d2 ⁴ is defined and evaluated.

[0028]

[Table 2]

[0029]

[Table 3]

As is clear from each table, the conventional example 1 (1 ×
With 3 × d2 closed cord), the rubber permeability is poor, and with Conventional Example 2 (1 × 3 × d2 open cord), the cord elongation is large and it is easily deformed, and there are problems in rubber permeability and reliability. In Comparative Example 2 (steel cord having a 1 × (1 × d2 + 2 × d2) structure), the rubber permeability is enhanced due to the excellent gap forming performance between the strands and the shape retention of the cord, but the longitudinal elastic modulus In contrast to the decrease in the rigidity coefficient, Examples 1 to 3 (steel cords of 1 × (1 × d1 + 2 × d2) structure) are excellent in rubber permeability due to excellent gap forming performance between strands and shape retention of cords. And the longitudinal elastic modulus ratio and the rigidity coefficient are prevented from being lowered, and are moderately increased. Also, as in Comparative Example 1 ((1 × (1 × d1 + 2 × d2) steel cord), the wire diameter When the ratio d1 / d2 is increased, the rigidity coefficient becomes higher and the cord becomes too hard. , Its wire diameter ratio
d1 / d2 is 1.02 to 1.4 as is clear from the examples.
A range of 0 is preferred.

Further, as is apparent from Table 3, 1 ×
In a steel cord having a (1 × d1 + 2 × d2) structure, as in Comparative Example 3-a, if the cord twist angle β (3.0) is excessively reduced, the twisted shape of the cord becomes unstable, and Comparative Example 3 -As shown in b and c, the cord twist angle β
When (6.0, 6.5) is excessively increased, the strength utilization factor of the wire due to the decrease in twist is reduced, whereas in Example 2-a
~ E is in a good range 9 in which the strength utilization factor of the wire is not significantly reduced.
It is preferably 5% or more, the twisted shape of the cord is stabilized, and the twist angle β of the cord is preferably in the range of 3.5 to 5.5, as is clear from the examples.

In each of the above-mentioned illustrated examples and each sample shown in each table,
It is a steel cord for rubber reinforcement having a 1x3 structure formed by twisting three strands together, but a 1x4 structure or a 1x5 structure formed by twisting four or five strands together We also prototyped the steel cord for rubber reinforcement of, and confirmed that the same action and effect as in the case of the 1 × 3 structure can be obtained. The diameter of the thick wire is d1 and the diameter of the thin wire is Assuming that the diameter is d2, the wire diameter ratio d1 / d2 = 1.02 to 1.
40 is represented by the formula d1 = (1.02 to 1.04) × d2, and assuming that the number of strands is N, the twist angle β of the cord is 3.5 = 5.5

[0033]

[Equation 1]

## EQU1 ## and is applied as a common formula to the rubber reinforcing steel cords of 1 × 3 structure, 1 × 4 structure and 1 × 5 structure.

Further, the steel cord for rubber reinforcement of each of the above-mentioned embodiments is embedded in the belt portion of a steel radial tire and applied as a rubber reinforcement layer thereof, and its rubber reinforcement performance, reliability and tire uniform property as well as durability are provided. Is effectively increased.

[0036]

As described above, according to the present invention, in the steel cord for rubber reinforcement formed by twisting three to five strands as described above, at least one strand of the strands has a pitch or a corrugation height. The diameter d1 of a wire formed into a compound spiral formed by different shaping and twisting, and the diameter d1 of the wire formed in the above-mentioned compound spiral is expressed by the equation d1 =
(1.02 to 1.04) × d2, and the twist angle β of the cord is expressed by the following formula with respect to the number N of strands.

[0037]

[Equation 1]

With a twisted structure satisfying the above conditions, the performance of forming a gap between the strands of a steel cord for rubber reinforcement and a steel radial tire, the cord shape retention property, and the longitudinal elastic modulus and rigidity of the cord are appropriately increased to allow rubber penetration. Durability, as well as durability, reliability and tire uniformity.

[Brief description of drawings]

FIG. 1 is a side view and a sectional view of a main part showing an embodiment of a steel cord for rubber reinforcement of the present invention.

FIG. 2 is a side view (A) of each of the molding and twisting, in which the steel cord for rubber reinforcement of the present invention is disassembled into each wire.
(D)

FIG. 3 is a side view showing an embodiment of a manufacturing apparatus.

FIG. 4 is a side view mechanism diagram (A) showing each embodiment of the molding mechanism.
(B).

[Explanation of symbols]

 1,2,3 strands a, b compound spiral d1 d2 strand diameter Pa type pitch Pitch Ha wave height P twisted pitch H twisted height N number of strands S gap β cord twist angle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B60C 9/18 E 8408-3D

Claims (4)

[Claims] 1. A rubber-reinforcing steel cord formed by twisting three to five strands together, wherein at least 1.
The strands of the book are a little thicker than other strands,
A steel cord for rubber reinforcement, characterized in that it is formed into a compound spiral by forming a pitch or another type with different corrugation height and twisting to form a gap with other strands. 2. The rubber-reinforcing steel cord according to claim 1, wherein the diameter d of the strand formed into a composite spiral shape.
1 is a steel cord for rubber reinforcement, characterized in that it has a large diameter that satisfies the following formula d1 = (1.02 to 1.04) xd2 with respect to the diameter d2 of other strands. 3. The steel cord for rubber reinforcement according to claim 1 or 2, wherein the steel cord has a twist angle β.
Is the following equation for the number N of strands: A steel cord for rubber reinforcement, which has a twisted structure that satisfies the above requirements. 4. The rubber-reinforcing steel cord according to claim 1, 2 or 3, further comprising a rubber-reinforcing layer formed by embedding the steel cord in a belt portion of a tire. Steel radial tires.