JP3079295B2 - Steel cord for rubber reinforcement - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord for rubber reinforcement suitable as a rubber reinforcement for steel radial tires, high-pressure hoses, belt cords and the like. 2. Description of the Related Art Conventionally, a large amount of steel cord is used as a rubber reinforcing material for steel radial tires such as trucks and buses, and steel cords having various structures differing from tire to tire are applied. Have been. In particular, the carcass portion has a small diameter (e.g.
3 + 9 formed by twisting many strands (175 mm)
Steel cords of + 15 × 0.175 structure and 7 × 4 × 0.175 structure are typical, and these steel cords are manufactured by twisting a large number of strands in two or three steps. As the cost increases, the rubber hardly penetrates into the central part of the cord, and improvement of its corrosion resistance and the like has become an issue. Recently, the number of strands has been reduced by slightly increasing the diameter of the strands, and the strands are formed by twisting all 12, 12, or 27 strands at once with the same twisting direction and similar twist pitch. Steel cords having a 1 × 12 structure, a 1 × 19 structure, and a 1 × 27 structure have been developed and proposed. Such a bunched type steel cord can be manufactured by twisting a large number of strands at a time and can be provided at low cost. There is an advantage that the rubber easily penetrates due to the decrease in the amount. However, in the bunched type steel cord, for example, in a 1 × 12 structure, FIG.
When the steel cord 13a is formed by twisting twelve strands of the same diameter as shown in FIG. 1, the shape is constituted by three core strands 11 and nine side strands 12, and all the strands are formed. The wires are tightly and compactly twisted, so that the rubber does not easily penetrate the inner layer. As a remedy, a steel cord 13b in which three core strands 11b are made thicker to form a gap between the nine side strands 12 to increase rubber permeability as shown in FIG. And proposed as a core diameter increasing cord. In the 1 × 19 structure, if a steel cord is formed by twisting 19 strands having the same wire diameter, 1
Core wire, 6 middle wires and 12 side wires. The core wires are hardly formed and are straight. The strand has less typing,
The side strands have a structure in which rubber is hardly permeated into the inner layer part when the molding is the largest. As a remedy, a core cord with a large diameter and a gap between the middle strand and the side strand to form a steel cord with increased rubber permeability has been proposed as a core increased cord. I have. The conventional bunched steel cord has the advantage that it can be manufactured by twisting a large number of strands all at once and can be provided at low cost. Although the rubber permeability is improved by constructing the core-increased cord as described above, the core element wire having a relatively small molding rate and a low (short) core stranding rate (length) in the cord longitudinal direction is low. Since the diameter is increased, the burden of tensile stress and bending stress on the core wire increases, which is disadvantageous for tire fatigue and may lead to breakage of the core wire. I'm sorry. SUMMARY OF THE INVENTION The present invention has been developed to solve the above-mentioned problems. The object of the present invention is to reduce the manufacturing cost and to improve the burial performance and durability.
Comprehensive rubber, such as enhancing fatigue and rubber permeability
An object of the present invention is to provide a steel cord for rubber reinforcement with improved reinforcement performance . According to the present invention, a wire diameter ratio R between a wire diameter d1 of a core wire and a wire diameter d2 of a side wire is d1 / d2.
= 0.95 ± 0.025, and four core strands and
It is composed of nine side strands and all cores
The strand and all side strands are twisted at once with the same twist direction and similar twist pitch, and are configured as a bunched type.
As well as saving costs as a 1 × 13 structure,
Wire diameter ratio R (The wire diameter of the core wire is appropriately smaller than the side wire.
The core wire is increased by one and the core
The burial performance is improved without extraordinary increase in
Breaking load of the core wire) and the side portion (9 side wires)
(Tensile stress and bending stress) to improve fatigue resistance
To form a suitable gap between the side wires to improve rubber permeability.
Excellent embedding performance, fatigue resistance and rubber permeability
An object of the present invention is to provide a steel cord for rubber reinforcement that effectively improves rubber reinforcement performance comprehensively . The wire diameter ratio R between the wire diameter d1 of the core wire and the wire diameter d2 of the side wire is d1 / d2 = 0.95 ± 0.025 .
Consist of four core strands and nine side strands
In addition, all core strands and all side strands are twisted at the same time in the same twisting direction and the same twist pitch, so that the bunched type manufactured by twisting in one step is 1 × The 13 structure significantly reduces the manufacturing cost, and the steel cord is the same as the conventional 1 × 1
Compared with the steel cord having the two structures, the wire diameter ratio R is set as above, ie,
Reducing the diameter of the core wire to an appropriately smaller and smaller diameter than the side wire
And the core diameter is increased by one, so the cord diameter is
It is not particularly increased and the embedding performance in rubber is improved
From the core consisting of four core strands and nine side strands
Tensile stress, bending stress, etc., with both sides
To approximately the same level to effectively increase fatigue resistance
I have. In addition, form an appropriate gap between the side wires
Excellent burial performance and fatigue resistance, including enhanced rubber permeability
Steel for rubber reinforcement that has both properties and rubber permeability
The rubber reinforcement performance is effectively improved overall . FIG. 1 shows an embodiment of the present invention, and FIGS. 2 (A) and 2 (B).
(C) shows a comparative example. In the figure, 1, 1a, 1c and 1d are core strands, 2 is a side strand, 3a, 3b, 3c and 3d are rubber cords for reinforcing rubber, d1 is the diameter of the core strand and d2 is
Diameter side Bumotosen, R (not shown), d1 / d2 is filed with a line diameter ratio of the wire diameter of the wire diameter and the side strands of the core wire, the embodiment shown in Figure 1, The wire diameter ratio R between the wire diameter d1 of the core wire 1a and the wire diameter d2 of the side wire 2 is d1 / d2 = 0.95 ± 0.0.
25, and four core strands 1a and nine side strands
2 and all the core element wires 1a and
This is a steel cord 3a for rubber reinforcement, wherein all side strands 2 are twisted at a time with the same twist direction and the same twist pitch. More specifically, the core element wire 1a and the side element wire 2 are preferably made of a high-carbon steel wire containing 0.82% by weight of carbon by applying a copper or zinc plating by a diffusion plating method. , And then alloyed by heat treatment to form copper Cu 63.
5% by weight, with a plating amount of 4.0 g / kg,
A wire obtained by successively drawing the wire into a small diameter using a die to form a predetermined wire diameter is used, and the wire diameter of the core wire 1a is set to d.
1, if the wire diameter of the side wire 2 is d2, the core wire 1
The wire diameter ratio R between the wire diameter d1 of a and the wire diameter d2 of the side element wire 2 is d.
1 / d2 = 0.95 ± 0.025.
That is, the core wire 1a is configured to have a moderately small diameter with respect to the side wire 2, and the number of the core wire 1a is increased to four to 9
With a buncher-type stranded wire machine together with two side strands 2,
If necessary, each element wire is appropriately shaped and twisted at a time to form a rubber cord 3a having a 1 × 13 structure (bunched type) as described above. further,
It is preferable that a small-diameter wrapping wire 5 is entangled with a large helical pitch in the reverse twist direction on the outer side of each side element wire 2, so that the shape retention of the cord is enhanced. As a result of a detailed examination of the progress of breaking of each strand in a fatigue test, the conventional bunched type steel cord shows that the core strand and the side strand all have the same twist direction and similar twist at the same time. Since the core is twisted with a pitch, the shaping rate of the core strand is smaller than that of the side strand, and the twisting rate (length) of the core strand twisted in the longitudinal direction of the cord is relatively short. The core wire bears a large amount of tensile stress applied to the cord, and a large bending stress proportional to the wire diameter is applied, and this tendency becomes remarkable as the diameter of the core diameter increasing cord, that is, the core wire increases. As a result, it was found that the core wire was broken. On the other hand, the steel cord 3a for rubber reinforcement of the present invention has a wire diameter d1 of the core wire 1a and a wire diameter d1 of the side wire 2.
2 and d1 / d2 = 0.95 ± 0.025, and all four core strands 1a and nine side strands 2 have the same twisting direction and the same twist direction. By being twisted at once with a twisting pitch, the core wire 1
a is appropriately reduced in diameter with respect to the side strands 2 and is increased to four, and the fatigue resistance of the core strands is effectively increased, and is equalized with the side strands. In addition, the fatigue resistance is remarkably improved, and the occupied cross-sectional area of the cord core formed by the four core strands is moderately increased, so that the rubber permeability is increased. [Table 1] [Table 2] The samples shown in Tables 1 and 2 have a wire diameter of 0.20.
mm, 0.205 mm, and 0.21 mm side wires, the core wire having the same diameter, a large diameter or several kinds of small diameters, and a combination of 3 or 4 core wires and 9 Steel cords of various 1 × 12 structure and 1 × 13 structure (bunched type) formed by twisting all the side strands at the same time in the same twist direction and the same twist pitch are manufactured, and FIG. As shown, a bunched type consisting of four core strands 1 (smaller in diameter than the side strands ) and nine side strands 2 is 1 × 13.
Example 1, 2, 3, FIG. 2
As shown in (B), a steel cord 3b having a 1 × 13 structure composed of four core strands 1 ( having the same diameter as the side strands ) and nine side strands 2 was used in Comparative Example 1 and FIG. As shown in (C), a steel cord 3c having a 1 × 13 structure composed of four core strands 1c (smaller in diameter than the side strands ) and nine side strands 2 was used in Comparative Example 2, and And three core element wires 1 as shown in FIG.
1 (same diameter as the side strand ) and 9 consisting of nine side strands 12
× 12 structure steel cord 13a in Conventional Example 1, FIG.
As shown in (B), three core strands 11b ( side strands)
On the other hand , as shown in FIG. 2A, a steel cord 13b having a 1 × 12 structure composed of 9 pieces of side wires 12 (thick diameter) and three side wires 12 was used as three core wires 1d ( side wires). for small diameter) and 9
And the steel cord 3d of 1 × 12 structure consisting of the side strands 2 that the comparative example 1, the code size of each of these samples, along with breaking load, rubber penetration, 3 by measuring the roll fatigue An evaluation as shown was obtained. The three-roll fatigue was evaluated by embedding the steel cord of each sample in a long rubber compound and vulcanizing it into a rubber block compound, and repeatedly bending the three rolls under an appropriate tensile load. and index measures the number of times up to the fatigue fracture distorts, also rubber penetration, place rubber Bro arrive samples (length 14 mm) in water, the other end to supply the compressed air Ri by one end This is a measurement of the amount of leak air flowing out. As apparent from Tables 1 and 2, Examples 1 and 2
2 and 3 have a smaller cord diameter than the conventional example, the comparative example and the comparative example.
It will not be particularly increased and will be secured almost in the same way as the conventional example
, Core (four core strands) and side (9 side strands)
And both breaking loads are almost balanced, effectively improving fatigue resistance.
It is raised and has a moderate gap between the side strands.
A gap is formed to ensure sufficient rubber permeability . When the core wire and the side wire have the same wire diameter as in Comparative Example 1, the core portion (four core wires) is increased only by increasing the core wire to four wires.
The breaking load of both the side strands) and the side parts (the nine side strands)
It is balanced and no improvement in fatigue resistance can be expected. If the diameter of the core element wire is excessively small as in Comparative Example 2, rubber permeability cannot be ensured. As in the first, second, and third embodiments, a bunched type including four core strands and nine side strands is used.
× 13 structure and the wire diameter d of the core element wire 1a
By setting the wire diameter ratio R between the wire diameter 1 and the wire diameter d2 of the side wire 2 within the range of d1 / d2 = 0.95 ± 0.025, the cord diameter is significantly increased.
Instead , both breaking loads of the core composed of the four core strands and the side composed of the nine side strands are also maintained at substantially the same level,
Moreover, the rubber permeability Ru is well secured. In addition, rubber reinforcement
In steel cords for use, the smaller the cord diameter, the more the rubber thickness can be reduced. Further, the cord breaking load and the cord diameter are preferably substantially at the same level of 2% or less because this leads to a change in tire design. The present invention has the above-described configuration,
Wire diameter ratio R of wire diameter d1 of core wire and wire diameter d2 of side wire
Is set to d1 / d2 = 0.95 ± 0.025 and is composed of four core strands and nine side strands, and all core strands (four) and all nine strands (9) side strands at the same twist direction and similar twist pitch at a time, so that they can be easily twisted in one step to form a bunched type 1x13 steel cord. The cost can be greatly reduced, and the wire diameter of the core wire with respect to the wire diameter of the side wire as compared with the conventional steel cord having a 1 × 12 structure has the wire diameter ratio R as described above. Reducing the diameter to a moderately small size and using only one core wire
By increasing the number of cords to four, the embedding performance in rubber is improved without significantly increasing the cord diameter, and the core part (four core strands) and the side parts (nine side strands) ) And both breaking loads (tensile stress and bending stress, etc.) are balanced to increase fatigue resistance,
Moderate rubber penetration to form an appropriate gap between the side portions strand
It has excellent burial performance, fatigue resistance, rubber permeability, etc., and effectively improves overall rubber reinforcement performance.

[Brief description of the drawings] FIG. 1 is a cross-sectional view showing one embodiment of the present invention. FIG. 2 is a cross-sectional view showing a comparative example (A), (B) and (C). FIGS. 3A and 3B are cross-sectional views showing a conventional example. [Explanation of symbols] 1a Core strand 2 Side strand 3a Steel cord for rubber reinforcement d1 wire diameter (core wire) d2 wire diameter (side wire) R wire diameter ratio

Claims (1)

(57) [Claims] The wire diameter ratio R of the wire diameter d1 of the core wire and the wire diameter d2 of the side wire.
Is set to d1 / d2 = 0.95 ± 0.025, and four
It is composed of a core strand and nine side strands.
A steel cord for rubber reinforcement , wherein all core strands and all side strands are twisted at a time in the same twisting direction and at the same twist pitch.