JP3464547B2 - Steel cord - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord which is widely used for industrial purposes, and particularly used as a reinforcing material for belts, tires and the like.

[0002]

2. Description of the Related Art Conventionally, steel cords used for reinforcing construction vehicle tires and reinforcing conveyor belts are required to have high strength and have a double twist structure in which strands formed by twisting filaments are further twisted. Steel cords are widely used.

[0003]

However, when the steel cord having such a double twist structure is used, for example, for reinforcing a rubber article, rubber hardly penetrates into the cord and external damage reaches the reinforcing steel cord. Then, there is a problem that moisture penetrates, propagates inside the cord, propagates in the longitudinal direction, and corrodes the cord, which shortens the durable life of the product. Further, even if there was no external damage, the filament that was not bonded to the rubber inside the cord was not restrained by the rubber, so that it repeatedly jumped out of the composite due to bending input, leading to a failure.

Therefore, it is conceivable to use a 1 × 5 open twisted cord having good rubber permeability inside the strand, but when the open twisted cord is further twisted, the steel cord is closed due to the contact pressure with the adjacent strand. It is in a state and the expected effect cannot be obtained.

An object of the present invention is to provide a steel cord having sufficient durability without the cord being closed due to pressure during vulcanization.

[0006]

Means for Solving the Problems The present inventor has conducted extensive studies in order to achieve the above-mentioned object, and as a result, the core filament has an appropriately corrugated 1 + 6 structure as one strand, and the strands are twisted together. It was found that sufficient rubber can be stably permeated into the steel cord after pressure vulcanization, and the present invention was completed.

That is, the present invention is as follows: (1) At least a part of the strands comprises a core made of one steel filament and a sheath made of six steel filaments arranged around the core, The filament is corrugated, and the amplitude Lc of the corrugation and the filament diameter d of the core filament are
The patterning rate Rc (= Lc / dc) represented by the ratio with c is
2. If 0.12 ≦ Rc ≦ 1.5 and the pitch Pc of the corrugated pattern is the core filament diameter dc, 3.
A steel cord for reinforcing a rubber article having a double-twisted structure using a strand of 0 dc / 0.34 ≦ Pc ≦ 10.0 dc / 0.34.

(2) In a multi-twisted steel cord consisting of one core strand and six sheath strands arranged around the core strand, at least one strand of each strand is described in (1). Is a steel cord for reinforcing rubber articles.

(3) In a multi-twisted steel cord consisting of one core strand and six sheath strands arranged around the core strand, all strands have the structure described in (1), and a rubber article is reinforced. It is a steel cord for.

(4) In a multi-twisted steel cord in which 2 to 5 strands are twisted in a single layer, at least one of the strands is a steel cord for reinforcing rubber articles having the constitution described in (1). is there.

(5) In a multi-twisted steel cord in which 2 to 5 strands are twisted in a single layer, all the strands are steel cords for reinforcing rubber articles having the structure described in (1).

(6) In a multi-twisted steel cord consisting of two core strands and 6 to 8 sheath strands arranged around the core strands, at least one of the strands is described in (1). Is a steel cord for reinforcing a rubber article having the above structure.

(7) In a multi-twisted steel cord composed of two core strands and 6 to 8 sheath strands arranged around the core strands, all the strands have the structure described in (1). A steel cord for reinforcing goods.

(8) A steel cord for reinforcing a rubber article having the structure described in (6) to (7), characterized in that two core strands are aligned in parallel.

(9) The steel cord for reinforcing rubber articles according to any one of (1) to (8), wherein the core filament diameter dc and the sheath filament diameter ds are substantially dc = ds in at least a part of the structure of the strands. is there.

[0016]

The present invention will be described in detail below. In the present invention, the core filaments of the strands are corrugated. It is important that this corrugation has a specific range of amplitude and pitch due to the strands of the 1 + 6 structure, which secures a gap for rubber permeation between sheath filaments. Has good productivity,
Because of the low cost, if the core filament is corrugated, the strand itself becomes flat, and if this is used for the core strand, the arrangement of the sheath strand will be moderately dispersed, and the permeability of the rubber inside the cord will be good. This is because there are advantages such as increased corrosion resistance.

As a result, in the conventional multi-twisted cord, the permeability of rubber was insufficient and there was a problem in corrosion resistance. However, when the strand of the present invention is used, the sheath strand has a dense structure. Even when they are in contact with each other, the effect of sufficient rubber permeability is exhibited.

When the number of the sheath filaments of the strand is 6, that is, in the case of the 1 + 6 structure, the molding ratio Rc of the core filament (= Lc / dc, where Lc is the amplitude of the waveform and dc is the diameter of the core filament) is 0. .12 ≦ R
c ≦ 1.5. When Rc is smaller than 0.12, the effect of dispersing the arrangement of the sheath, ensuring the proper gap between the sheaths, and permeating the rubber into the cord is insufficient, and Rc is 1.0.
This is because the cord properties are poor, and stress is not evenly applied when a tensile load is applied to the cord, and the cord strength is reduced.

Regarding the corrugated patterning pitch Pc of the core filament of the strand, 3.0 dc / 0.34≤Pc
≦ 10.0 dc / 0.34. Pc is 10.0 dc
If it is larger than /0.34, the arrangement of the sheath will be dispersed, the sheath gap will be properly secured, and the effect of permeating the rubber inside the cord will be insufficient. If Pc is smaller than 3.0 dc / 0.34, it will be The strength is lowered due to the load on the core filament, or the core strength and the sheath filament are not evenly applied when a tensile load is applied to the cord, resulting in insufficient cord strength.

The typed waveform here is preferably a waveform having a gentle curve such as a sine wave or a circular arc rather than a shape with a sharp vertex such as a triangle, and stress is concentrated at the vertex. Can be prevented.

In particular, in the case of a double-twisted structure having one core strand and six sheath strands, it has been difficult for rubber to penetrate into the inside, but by using the strand of the structure of the present invention, rubber sufficiently penetrates. .

Also, in the case of a double-twisted structure in which two to five strands are twisted in a single layer, it has been difficult for the rubber to intrude into the inside, but by using the strand of the structure of the present invention, the rubber sufficiently intrudes. To do.

Also in the case of a double twist structure consisting of two core strands and 6 to 8 sheath strands, it has been difficult for the conventional rubber to penetrate into the interior, but by using the strand of the structure of the present invention, it is possible to obtain sufficient rubber. Invades. Further, this effect is obtained even when the core strand is in a straight shape in which the strands are not twisted.

When the core filament diameter of the strand is made smaller than the sheath filament diameter, the spacing between the sheath filaments becomes narrow, rubber is hard to enter, and the rigidity of the core becomes weak, so that the effect of molding is deteriorated.
Further, when the core filament diameter is made larger than the sheath filament diameter, there are problems such as an increase in cord weight and deterioration in productivity. Therefore, it is preferable that the core filament diameter dc and the sheath filament diameter ds have substantially the same diameter from the viewpoint of improving the productivity in the manufacturing process.

As a reinforcing material, in order to secure the strength and reduce the weight of the rubber composite, the carbon content is 0.80 to 0.80.
It is preferable to use a steel cord made of 0.85% by weight of high-pitched steel.

Even if a spiral filament is added to the multi-twisted cord of the present invention, the same effect as described above can be obtained.

[0027]

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples. A steel cord made of a strand having a cord structure, a core corrugation patterning ratio Rc, a core corrugation pitch Pc, a sheath corrugation pitch Ps, a core filament diameter dc, and a sheath filament diameter ds described in Table 1, Table 2, Table 3, and Table 4. A radial tire for a construction vehicle having a size of 3600R51 equipped with a belt in which was embedded was prototyped, and corrosion resistance (separation resistance) and cord strength of each tire were examined. The results are shown in Table 1.
~ Also shown at the bottom of Table 4. 2 × (1+ of Example 9)
6) + 6 × (1 + 6) +1 indicates that two cores are aligned in parallel.

For corrosion resistance, the belt cord with rubber covered was taken out 100 mm from the tire, the side surface was covered with silicon celite, and one end of the cord was dipped in a 10% NaOH aqueous solution to form an aqueous solution only from the cut surface. Was infiltrated and then penetrated for 24 hours, and the rubber was pinched with a pair of pliers and peeled off. The exposed metal portion was defined as a corrosion propagation portion, and the length (mm) was evaluated.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

[0033]

EFFECT OF THE INVENTION The steel cord using the strand of the present invention has good productivity, is less affected by variations in the process, and has good rubber permeability so that it has good corrosion propagation resistance and cord strength. Since it can be held, it can be used as a rubber reinforcing material to improve the durability of a rubber composite pair such as a tire and to greatly improve its service life.

[Brief description of drawings]

FIG. 1 is a part of a sectional view of a steel cord having a strand of 1 + 6 structure according to the present invention.

FIG. 2 is a part of a cross-sectional view of a steel cord having a conventional 1 + 6 structure strand (having a large core diameter and not having a mold).

FIG. 3 is a cross-sectional view of a corrugated surface of a corrugated core of the present invention, which is an explanatory diagram of a core wire diameter dc, a waveform amplitude Lc, and a waveform pitch Pc.

[Explanation of symbols]

1,3 core filament 2, 4 sheath filament dc core wire diameter Lc Core waveform amplitude Pc core waveform pitch

─────────────────────────────────────────────────── --Continued from the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) D07B 1/06 B60C 9/00

Claims (9)

(57) [Claims] 1. The composition of at least some of the strands comprises:
A core made of one steel filament and a sheath made of six steel filaments arranged around the core are provided, and the core filament has a corrugated shape. The amplitude Lc of the corrugated shape and the core filament The molding rate Rc (= Lc / d expressed as a ratio with the wire diameter dc
c) is 0.12 ≦ Rc ≦ 1.5, and the pitch Pc of the corrugated pattern is 3.0 dc / 0.34 ≦ Pc ≦ 10.0 dc / 0.
A steel cord for reinforcing a rubber article having a double twist structure using a strand of No. 34. 2. In a multi-twisted steel cord comprising one core strand and six sheath strands arranged around the core strand, at least one of the strands has the structure according to claim 1. A steel cord for reinforcing certain rubber articles. 3. A multi-twisted steel cord comprising one core strand and six sheath strands arranged around the core strand, all strands having the structure according to claim 1 for reinforcing a rubber article. Steel cord. 4. A multi-twisted steel cord in which 2 to 5 strands are twisted in a single layer, and at least one of the strands is a steel cord for reinforcing rubber articles, wherein the strand has the structure according to claim 1. 5. A steel cord for reinforcing rubber articles, wherein in a multi-twisted steel cord in which 2 to 5 strands are twisted together in a single layer, all the strands have the structure according to claim 1. 6. A multi-twisted steel cord comprising two core strands and 6 to 8 sheath strands arranged around the core strands, wherein at least one of the strands is one of the strands. Steel cord for reinforcing rubber articles, which is a component. 7. A multi-twisted steel cord comprising two core strands and 6 to 8 sheath strands arranged around the core strands, all strands having the structure according to claim 1. Steel cord for reinforcement. 8. A steel cord for reinforcing a rubber article having a structure according to claim 6, wherein two core strands are aligned in parallel. 9. The steel cord for reinforcing a rubber article according to claim 1, wherein the core filament diameter dc and the sheath filament diameter ds are substantially dc = ds in the constitution of at least a part of the strands.