JPH09228268A - Steel cord with two-layer structure and radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radial tire excellent in corrosion resistance with long service life by using steel cords of multi-layer structure with excellent rubber infiltrativity for reinforcing the belt or carcass of the tire. SOLUTION: Two units of IN-OUT type buncher strander are linked interlockingly with each other, and (k) wires 10 are stranded together by the 1st strander into a 1st strand 1, which is then bundled with (m) wires prepared separately from the 1st strand nearly in a parallel fashion into a 2nd strand 3, which, in turn, is fed to the 2nd strander where (n) wires 40 are entwined around the 2nd strand 3 to obtain the objective steel cord with two-layer structure. The other objective automotive radial tire is obtained by using these steel cords in at least part of the belt or carcass of the radial tire.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a two-layer structure steel cord used for reinforcing rubber products and a radial tire using the same.

[0002]

2. Description of the Related Art A steel cord formed by twisting a plurality of steel strands is generally used for a reinforcing layer of a belt portion or a carcass portion of a radial tire for an automobile. As such a steel cord, a single-layer cord of one-step twist in which four to five strands are twisted at the same time is generally used for a belt of a passenger car tire. On the other hand, for belts of light truck tires and carcasses of heavy truck / bus tires,
A two-layer structure with a two-step twist in which a plurality of strands are twisted around a core strand in which two to four strands are twisted at the same time, or a plurality of strands around a two-layer structure A three-layer structure having a three-step twist is used. Of course, from the viewpoint of the manufacturing cost of the cord, the single-layer structure is preferable to the two-layer or three-layer structure, but the tire size becomes large due to the supporting load like tires for light trucks, large trucks and buses. When it comes, the steel cord used for reinforcement is inevitably required to have high strength. However, the single-layer twisted cord lacks the strength of the cord because it has a small number of strands. Therefore, it is necessary to increase the number of strands as the cord, and there is no choice but to use a cord having a two-layer structure or a three-layer structure, which is expensive to manufacture.

As a concrete example of the above-mentioned two-layer steel cord, 1 × 2 + 7 whose cross section is shown in FIG. 1 (a) is mainly used for belt reinforcement of a light truck tire.
Further, in the carcass reinforcement of truck / bus tires, 1 × 3 + 9 whose cross section is shown in (b) is mainly used. In such a structure, the twisting is performed in two steps as described above, so that the production cost is increased. Also, 1 ×
In the 3 + 9 steel cord, there is almost no gap between the individual strands, as is clear from FIG. 1 (b). For this reason, rubber penetration into the inside of the cord is poor, causing a problem in corrosion resistance. In order to improve this, the number of strands on the side is reduced to 1 × 3 + 8 so that a gap is provided between the strands of the outer layer. However, even if this structure is adopted, the core strand (inner layer)
For 1 × 3, there is almost no gap between the wires, so
It is difficult to penetrate the rubber to the center of the cord.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to have a very good rubber permeability, a simple manufacture and a low cost. The purpose is to provide a two-layer steel cord that can be produced at. Another object of the present invention is to provide a radial tire having excellent corrosion resistance and long life.

[0005]

To achieve the above object, the present invention provides a second strand in which a first strand formed by twisting k strands and a bundle of m substantially parallel strands are bundled substantially in parallel. In addition, n strands are twisted around the second strand. More specifically, the steel cord connects an IN-OUT type buncher twisting machine, that is, a supply bobbin of a raw wire inside the machine, and two twisting machines of a type in which a take-up reel of a twisted cord is outside the machine. , Made by interlocking, k strands are twisted together by the first twisting machine to form the first strand, and the first strand and the second strand
The m strands supplied from outside the stranding machine are bundled and introduced into the second stranding machine to form the second strand, and n strands from inside the second stranding machine are arranged around this second strand. The strands are supplied and twisted, and moreover, the first strands forming the second strands and the m strands from outside the twisting machine are twisted in a substantially parallel state. Further, the radial tire of the present invention has a configuration in which the steel cord having the above configuration is used for at least a part of the belt portion or the carcass portion.

[0006]

2 and 3 show a first embodiment of a two-layer steel cord according to the present invention. Reference numeral 1 denotes a first strand, which is formed by twisting three strands 10, 10, 10. Reference numeral 2 is a bundle of strands, which is three strands 20, 20, 20 which are bundled in substantially parallel without being twisted together.
Consists of The first strand 1 and the wire bundle 2 are not twisted with each other but are bundled substantially in parallel to form a second strand 3. 40, 40, 40 are three strands twisted around the second strand 3, and due to such a relationship, as a whole (1 × 3 + 3) +
It has a 1x3 structure.

FIG. 4 shows a second embodiment of the present invention,
Reference numeral 1 is a first strand obtained by twisting three strands 10, 10, 10. 2 is a bundle of strands, which are six strands 20, 20, 2 which are bundled in substantially parallel without being twisted together.
It consists of 0, 20, 20, and 20. The first strand 1 and the wire bundle 2 are not twisted with each other but are bundled substantially in parallel to form a second strand 3. Four
Reference numerals 0, 40 and 40 denote three strands twisted around the second strand 3, and have a structure of (1 × 3 + 6) + 1 × 3 as a whole due to such a relationship. In each of the examples, the strands 10, 20, 40 are made of steel wire having a diameter of 0.15 to 0.30 mm and the same diameter as that of brass plated on the surface.
The twist pitch of the cord and the twist pitch of the cord are equal. The first strand 1 is formed by twisting three strands together, but unlike the conventional core strand, a gap s is formed between the strands.

The present invention is not limited to the above-described embodiment, but the strand 10 of the first strand 1 and the strand 2 of the bundle 2 of strands.
The diameter may be different from 0, and the strands 40 twisted around may have different diameters. Also, the number of strands forming the first strand 1 is not 3 but 2
The number of strands constituting the strand bundle 2 may be three,
It may be eight instead of six. Second strand 3
The number of strands 40 twisted around the wire may be four instead of three.

FIG. 5 shows a method of manufacturing the steel cord shown in the above-mentioned embodiment, in which A and B are two IN-OUT type buncher twisting machines (twisting twisting machines) arranged in parallel.
It is. In the twisting machine, that is, the first twisting machine A and the second twisting machine B, a required number of the wire supply bobbins 5A and 5B are arranged in the cradle, and the wires fed from the wire supply bobbins 5A and 5B are guided by the guide bows 6A and 6B. A cord is formed by twisting and twisting by rotating 6B ', and the cord is drawn out of the machine and wound up. In the first stranding machine A, k strand supply bobbins 5A are arranged in the cradle without rotating with respect to the fixed part of the machine. In this example, three wire supply bobbins 5A that are rotatable around their own axes are used. In addition, the second stranding machine B is also the first stranding machine A.
N wire supply bobbin 5B in the cradle
That is, in this example, three strand supply bobbins 5B that are rotatable around their own axis are arranged. The second stranding machine B is provided with a wiring board 7 having the same number of openings as the number of strands and a converging voice 8 on the downstream side of the strand supply bobbin 5B. Further, in the inlet area outside the rotating portion of the second stranding machine B, m (three in this example) rotatable wire supply bobbins 5C are arranged around their own axes to supply the wire supply. A winding reel 9 is arranged in the exit area on the opposite side of the bobbin 5C.

In the first stranding machine A, the strands 10, 10, 10 fed from each strand supply bobbin 5A are guided over the in-machine guide roll 50 and the guide bow 6A toward the guide roll 51 on the opposite side. , Is pulled out from the exit. During this period, the first bow 1 is twisted by the rotation of the guide bow 6A. In the first stranding machine A, when viewed from the outlet side, the rotating direction of the rotating portion is counterclockwise, for example. As described above, the first strand 1 drawn from the first twisting machine A is guided by the outlet guide roll 52 toward the inlet guide roll 53 of the second twisting machine B.
At this time, the strands of wire 20, 20, 20 are drawn out from the strand of wire supply bobbin 5C outside the machine at the same time, and these strands form a substantially parallel strand bundle 2 together with the first strand 1 from the inlet guide roll 53 to the second stranding machine. Introduced in B. here,
The guide roll 54 and the guide bow 6B are guided toward the guide roll 55 on the opposite side. Second stranding machine B
In, when viewed from the inlet side to the outlet side, the rotating direction of the rotating portion is clockwise. Therefore, the first strand 1 and the wire bundle 2 are twisted in the Z direction between the guide rolls 54 and 55 at the 180-degree symmetrical position to form the second strand 3. Further, in the second stranding machine B, the traveling direction of the second strand 3 is reversed by the guide roll 55, and this time, the second strand 3 is aligned with the rotation axis and goes from the outlet side to the inlet side. After passing through the aperture, it further passes through the convergent voice 8 toward the guide roll 56 near the inlet side.

On the other hand, in the second twisting machine B, the wires 40, 40, 40 are drawn out from the wire supply bobbin 5B, and these wires 40, 40, 40 are formed around the central portion of the wiring board 7. Convergence voice 8 by passing through each open hole
Inside the second strand 3 and the guide roll 5
Proceed in the direction of 6. Then, the traveling direction of the guide roll 56 is reversed again, the guide roll 56 passes over the guide bow 6B ′, passes through the guide roll 57 on the exit side, is guided to the outside of the machine, and is wound onto the winding reel 9. During this time, 180
The second strand 2 is twisted in the opposite direction, that is, the S direction in this example by the rotation of the guide bow 6B ′ between the guide rolls 56 and 57 at the degree symmetrical position, and at the time of passing the guide roll 57 on the outlet side, The first strand 1 twisted into 1 × 3 and the strands 20, 20, 20 fed from the outside of the machine are almost not twisted with each other. It becomes the second strand 3 in the state. Therefore, at the time of passing the final guide roll 57, three strands 40, 40, 40 are formed around the second strand 2 composed of the first strand 1 and the strands 20, 20, 20, which are substantially parallel to each other. It becomes a steel cord as shown in FIG. 2 which is twisted so as to be wound in the S direction. In addition, when the rotation direction of the second stranding machine B is set counterclockwise when the inlet side is viewed from the outlet side,
The three strands 40, 40, 40 around the strand are twisted in the Z direction. In the case of the second embodiment, the number of the strand supply bobbins 5C outside the machine is set to 6 and the strands 2 are respectively formed.
0, and the second stranding machine B together with the first strand 1
The other steps are the same as those described above. As a result, the steel cord shown in FIG. 4 is obtained.

The steel cord of the present invention has the above-mentioned I
Since it is obtained by connecting two N-OUT type buncher twisting machines and interlocking them, it can be efficiently manufactured in one step even though it has a two-layer structure. Then, the first strand 1 is twisted by the first twisting machine A and introduced into the second twisting machine B, and once twisted by the second twisting machine B with the strand bundle 2 introduced from outside the machine. After that, since it is twisted back in the opposite direction, a gap is created between all or a part of the strands 10, 10, 10 constituting the first strand 1. Therefore, in the finished steel cord, the rubber can be permeated into the portion of the first strand 1 very well.

Next, specific examples of the present invention will be shown. [Example 1] Normal strength with a diameter of 0.22 mm (tensile strength 30
A wire of 0 kgf / mm ² ) was used. As the twisting machine shown in FIG. 5, three strands are pulled out from the supply bobbin in the first twisting machine, twisted in the Z direction and led out as a first strand to the outside of the second twisting wire. Stranding wires from each of the three supply bobbins outside the machine, and introducing them into the second stranding machine together with the first strand into the second strand,
Furthermore, by pulling out the wires from the three supply bobbins in the second stranding machine and winding them out of the machine while twisting them around the second strand in the S direction (1 × 3
A steel cord having a +3) + 1 × 3 structure was obtained. The twist pitch of the first strand and the twist pitch of the cord are both 12
mm. For comparison, a steel cord of 1 × 2 + 7 structure was manufactured by the conventional method using the same strands as in Example 1 (Conventional Example 1). The twist pitch of this conventional example 1 is 6 mm /
12 mm, the twisting direction is the S direction.

Example 2 A high strength (tensile strength of 332 kgf / mm ² ) wire having a diameter of 0.22 mm was used. While pulling out three strands from the supply bobbin in the first stranding machine, twist them in the Z direction and lead them out of the machine as the first strand,
From each of the six supply bobbins outside the second stranding machine, the strands of wire are unwound and introduced into the second stranding machine together with the first strand into the second strand, and further from the three supply bobbins inside the second stranding machine. By pulling out the wire and twisting it around the second strand in the S direction and pulling it out of the machine and winding it up, a steel cord having a (1 × 3 + 6) + 1 × 3 structure was obtained. The twist pitch of the first strand and the twist pitch of the cord are both 14 mm. For comparison, a steel cord of 1 × 3 + 9 structure was manufactured by the conventional method using the same strand as in Example 2 (Conventional Example 2). Conventional example 2
The twist pitch is 6 mm / 12 mm, and the twist direction is the S direction.

Table 1 shows the results of testing the characteristics of the cords of Examples 1 and 2 and Conventional Examples 1 and 2. In Table 1, the cord diameter and the breaking load are based on the JIS G 3510 steel cord test method. For rubber permeability, a linear cord was vulcanized in rubber under a tension of 100 gf to prepare a sample, and then this cord was disassembled in the longitudinal direction, and the rubber permeability was visually observed. It was determined that 100% was completely covered with rubber.

[0016]

[Table 1]

From Table 1, it can be seen that Examples 1 and 2 are comparable in strength to those of the conventional example and have good rubber permeability, and that they are remarkably improved over the conventional example 2.

[0018]

According to claims 1 and 2 of the present invention described above, it is possible to obtain a steel cord having a two-layer structure in which the penetration of rubber is very good up to the center of the cord and the cost is low. Excellent effect can be obtained. According to the third aspect, the excellent effect that the radial tire having excellent corrosion resistance and long life can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a conventional two-layer structure steel cord.

FIG. 2 is a side view of the first embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of the first embodiment of the present invention.

FIG. 4 is a sectional view showing a second example of the present invention.

FIG. 5 is an explanatory view schematically showing a manufacturing state of a steel cord according to the present invention.

[Explanation of symbols]

 1 1st strand 2 strand bundle 3 2nd strand 10 strand 20 strand 40 strand A, B IN-OUT type buncher stranding machine

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B60C 9/22 B60C 9/22 B

Claims (3)

[Claims] 1. A first strand in which k strands are twisted together and a bundle of substantially parallel strands of m strands are bundled substantially in parallel to form a second strand, and n strands are arranged around the second strand. A double-layer steel cord characterized by being twisted together. 2. A first strand in which k strands are twisted together and a bundle of m substantially parallel strands are bundled substantially in parallel to form a second strand, and n strands are arranged around the second strand. The steel cord is made by connecting and interlocking two IN-OUT type buncher twisting wire machines.
The first stranding machine twists k strands into a first strand, and the first strand and m strands supplied from outside the second stranding machine are bundled into a second stranding machine. The second strand is introduced into the second strand, and n strands are supplied from the inside of the second stranding machine around the second strand and twisted together, and from the first strand and the outside of the stranding machine that constitute the second strand. M
A two-layer steel cord that is twisted together so that each strand of the book is in a substantially parallel state. 3. A radial tire for an automobile, wherein the steel cord according to claim 1 or 2 is used in at least a part of a belt portion or a carcass portion.