JPH1037086A - Steel cord for rubber article reinforcement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a steel cord capable of preventing reduction in productivity and improving twist stability, permeability of rubber, etc., fatigue resistance and corrosion resistance by winding plural sheath filaments having a prescribed diameter on the periphery of a core filament having a fixed diameter. SOLUTION: In this steel cord 10 for reinforcement of rubber article obtained by concentrically twisting strands 24, each strand 24 comprises a layer twisting structure composed of one core filament 26 and four sheath filaments 28 wound on the circumference of the core filament 26. When diameters of the core filaments 26 and the sheath filaments 28 are dc and ds, respectively, a relationship of 1.56<=ds/dc<=1.75 is satisfied. When the circumference of the core filament 26 is wound with five sheath filaments 28, preferably a relationship of 1.00<=ds/dc<=1.10 is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a steel cord for reinforcing rubber articles used as a reinforcing material for rubber articles such as pneumatic tires and industrial belts, and more particularly to a steel cord for reinforcing rubber articles having excellent durability. .

[0002]

2. Description of the Related Art In the field of steel cords for reinforcing rubber articles, it has been proposed to improve the durability of rubber articles by adopting a structure in which an elastic body such as rubber easily penetrates into the cords. Attempts have been made to improve the corrosion resistance by injecting rubber into the cord of a multi-twisted cord having an mxn structure in which m strands of n filaments are twisted together.

[0003]

SUMMARY OF THE INVENTION For example, Japanese Patent Application Laid-Open No. 2-1
Japanese Patent No. 04785 proposes a multi-twisted through cord having a single twist open structure in which a gap is formed between steel filaments in each strand. However, since the cord is easily stretched by a small force, workability during calendering is proposed. Inferior, there is also a problem with the dimensions of the product,
Further, there is a problem that tension is applied to the cord at the time of vulcanization in which the rubber enters the cord and the gap is narrowed, so that the rubber does not enter.

Japanese Patent Application Laid-Open No. Hei 5-18697 discloses a 3 × 4 in which a strand filament is corrugated.
Although a multi-twist cord has been proposed, there is a problem that the strength of the filament is lowered by corrugation and the number of corrugating steps is increased, so that productivity is reduced.

[0005] The present invention has been made in view of such circumstances, and its object is to prevent a decrease in productivity.
An object of the present invention is to provide a steel cord for reinforcing a rubber article, which can improve twist stability, permeability of an elastic body such as rubber, and fatigue resistance.

[0006]

According to a first aspect of the present invention, there is provided a steel cord for reinforcing a rubber article in which each strand is concentrically twisted, wherein each strand has one core filament and a periphery of the core filament. It has a layer twist structure in which four sheath filaments are wound. When the diameters of the core filament and the sheath filament are dc and ds, respectively, 1.56 ≦ ds / dc ≦
It is characterized by satisfying the relationship of 1.75.

The operation of the steel cord for reinforcing rubber articles according to claim 1 will be described. The reason why the cords are formed by concentrically twisting the strands is to improve the fatigue resistance. If the cord cross section is partially a 1 + 3 or 1 + 4 structure along the longitudinal direction of the cord, the deformation of the cord due to stress is reduced. It is not uniform and fatigue resistance is reduced.

[0008] The core of each strand is made of one steel filament. In the case of a core composed of three or more steel filaments, a space is formed in the center of the core. Corrosion of the filament occurs, and in the case of two filaments, the cross section of the strand becomes flat, the twist structure becomes irregular, and the cord utilization rate decreases. By using a single steel filament for the core, it is not necessary to allow rubber to penetrate into the core, and if the rubber enters the core surface, corrosion due to moisture can be prevented. In addition, since the cross section of the strand can be made circular, the cord power utilization rate can be improved.

The reason why the number of sheath filaments arranged around the core filament is four is that if the number is three or less, it is necessary to increase the diameter of the filament in order to obtain a required cord strength, and the fatigue resistance is reduced. That's why.

When the diameter of the core filament is dc and the diameter of the sheath filament is ds, the ratio of ds / dc is 1.56 ≦ ds / dc when there are four sheath filaments.
The reason for setting the range of ≦ 1.75 is that if it is less than this range, the core filaments will jump out due to the difference in the twisting rate in the cord twisting step, and the gap between the sheath filaments exceeding this range will be non-uniform and uniform rubber This is because it is difficult to obtain permeability.

According to a second aspect of the present invention, in the steel cord for reinforcing a rubber article in which each strand is twisted concentrically, each strand has one core filament and five sheath filaments around the core filament. It has a wound layer twist structure and is characterized by satisfying a relationship of 1.00 ≦ ds / dc ≦ 1.10 when the diameters of the core filament and the sheath filament are dc and ds, respectively.

The operation of the steel cord for reinforcing a rubber article according to claim 2 will be described. The reason why the cords are formed by concentrically twisting the strands is to improve the fatigue resistance. If the cord cross section is partially a 1 + 3 or 1 + 4 structure along the longitudinal direction of the cord, the deformation of the cord due to stress is reduced. It is not uniform and fatigue resistance is reduced.

[0013] The core of each strand is made of one steel filament. In the case of a core composed of three or more steel filaments, a space is formed in the center of the core. Corrosion of the filament occurs, and in the case of two filaments, the cross section of the strand becomes flat, the twist structure becomes irregular, and the cord utilization rate decreases. By using a single steel filament for the core, it is not necessary to allow rubber to penetrate into the core, and if the rubber enters the core surface, corrosion due to moisture can be prevented. In addition, since the cross section of the strand can be made circular, the cord power utilization rate can be improved.

The reason why the number of sheath filaments arranged around the core filament is set to five is that when the number of sheath filaments is six or more,
This is because it is necessary to increase the diameter of the core filament in order to secure a gap between the sheath filaments of the strand, and the fatigue resistance is reduced.

When the diameter of the core filament is dc and the diameter of the sheath filament is ds, the ratio of ds / dc is 1.00 ≦ ds / dc ≦
The reason for setting the range to 1.10 is that if it is less than this range, the core filaments jump out due to the difference in the twisting rate in the cord twisting process, and the gap between the sheath filaments exceeding this range becomes non-uniform, resulting in uniform rubber penetration. This is because it is difficult to obtain the property.

According to a third aspect of the present invention, in the steel cord for reinforcing a rubber article according to the first or second aspect, the twist direction of the strand and the cord is the same.

The function of the steel cord for reinforcing a rubber article according to claim 3 will be described. By setting the twist direction of the strand and the cord to be the same direction, when the cord is locally bent and deformed, the steel filaments at that portion are in line contact with each other, so that the contact force is reduced. As a result, fretting is reduced and fatigue fracture is reduced even when subjected to local repeated bending deformation.

According to a fourth aspect of the present invention, in the steel cord for reinforcing a rubber article according to any one of the first to third aspects, the sheath of each strand is provided in a sectional shape of the steel cord for reinforcing a rubber article. It is characterized in that the gap between the filaments is narrow on the center side of the cord and wide on the surface side.

The operation of the steel cord for reinforcing a rubber article according to claim 4 will be described. The reason for making the gap between the sheath filaments of each strand narrower at the center of the cord and wider at the front side when viewed from the cross-section of the cord is that the rubber on the front side has excellent adhesion to the filament, so it can cause repeated bending deformation of the cord. On the other hand, the movement of the filament is suppressed, and the fatigue resistance is improved.

According to a fifth aspect of the present invention, in the steel cord for reinforcing a rubber article according to any one of the first to fourth aspects, the number of strands constituting the steel cord for reinforcing the rubber article is in the range of 3 to 5. It is characterized by being.

The operation of the steel cord for reinforcing a rubber article according to claim 5 will be described. The number of strands constituting the steel cord was set in the range of 3 to 5
Below this, the cross section of the cord is flat and easily buckled, resulting in poor fatigue resistance, and in order to obtain the required cord strength, it is necessary to increase the diameter of the filament, which also causes a reduction in fatigue resistance. That's why. If the number is six or more, it is difficult to arrange the strands on concentric circles, so that the rubber permeability to the inside of the cord and the strands is reduced, and the corrosion resistance cannot be improved.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

[0023]

Embodiments Embodiments 1 to 7 of the steel cord for reinforcing rubber articles of the present invention will be described with reference to FIGS.

First, the process of manufacturing a steel cord for reinforcing a rubber article will be briefly described. When the carbon content is 0.70-0.
After reducing the diameter of the steel cord wire by 85% by weight to a predetermined diameter by dry drawing, it was subjected to a patenting treatment, followed by brass plating to obtain a steel filament having a final diameter by wet drawing.

The stranded wire has four wires around one core filament.
Alternatively, a strand was produced by winding five sheath filaments, and three to five of the strands were twisted concentrically to form a steel cord for reinforcing rubber articles.

FIGS. 1 to 7 show cross sections of an embodiment of the steel cord for reinforcing rubber articles manufactured in this manner, wherein 10 to 20 are steel cords for reinforcing rubber articles, 24 is strands, 26 is a core filament, 28
Indicates a sheath filament.

FIG. 1 shows 3 × (1) according to the first embodiment.
+4) shows a cross section of a steel cord 10 for reinforcing a rubber article having a structure, and FIG. 2 shows a 4 × (1+
4) A cross section of a steel cord 12 for reinforcing rubber articles having a structure is shown, and FIG. 3 shows a 5 × (1+
4) A cross section of a steel cord 14 for reinforcing a rubber article having a structure is shown, and FIG. 4 shows a 3 × (1+
5) A cross section of a rubber cord reinforcing steel cord 16 having a structure is shown, and FIG. 5 shows a 4 × (1+
5) A cross section of a steel cord 18 for reinforcing a rubber article having a structure is shown, and FIG. 6 shows a 5 × (1+
5) A cross section of a steel cord 20 for reinforcing a rubber article having a structure is shown, and FIG.
The cross section of a rubber article reinforcing steel cord 22 having a (1 + 4) structure is shown.

The twist direction of the strand 24 and the twist direction of the cord are the same. Further, in the steel cord 22 for reinforcing rubber articles of Example 7, each strand 24
The gap between the sheath filaments 28 is set narrow on the center side of the cord and wide on the front side.

The core filament diameter of the core filament 26, the sheath filament diameter of the sheath filament 28,
The strand pitch of the strand 24 and the code pitch of the steel cord 22 for reinforcing rubber articles are as shown in Table 1 below.

[0030]

[Table 1] The operations and effects of these embodiments 1 to 7 are as follows.

The core filament 26 of each strand 24
When the rubber infiltrates the surface of the core filament 26, corrosion due to moisture can be prevented, and the cross-section of the strand 24 can be made circular, so that the cord strength utilization rate can be improved.

Since the number of the sheath filaments 28 disposed around the core filament 26 is set to 4 to 5, the diameter of the sheath filament 28 is increased or the gap between the sheath filaments 28 is increased to obtain a required cord strength. Since it is not necessary to increase the diameter of the core filament 26 in order to secure it, it is possible to prevent a decrease in fatigue resistance.

The ratio ds / dc between the diameter dc of the core filament 26 and the diameter ds of the sheath filament 28 is set to 1.56 ≦ ds / d when four sheath filaments 28 are provided.
Within the range of dc ≦ 1.75, 5 sheath filaments 28
In the case of the book, the range of 1.00 ≦ ds / dc ≦ 1.10 is set, so that the core filament 26 can be prevented from jumping out and the gap between the sheath filaments 28 can be made uniform, so that a uniform rubber permeability can be obtained. Can be

Since the twist direction of the strand 24 and the cord is the same, when the cord is locally bent and deformed,
Since the steel filaments at that portion are in line contact with each other, the contact force is reduced. As a result, fretting is reduced and fatigue fracture is reduced even when subjected to local repeated bending deformation.

Further, since the number of bundles of the strands 24 is in the range of 3 to 5, the cord cross section can be made circular and the strands 24 can be arranged concentrically, so that fatigue resistance is secured. In addition, rubber permeability into the cord and into the strands 24 can be ensured.

In the rubber cord for reinforcing the rubber article 22 of the seventh embodiment, since the gap between the sheath filaments 28 on the outside of the cord of the land 24 is open, the rubber on the cord surface side when embedded in the rubber article is used. Suppresses the movement of the sheath filament 28 against repeated bending deformation of the cord, thereby improving fatigue resistance.

(Test Examples) In order to confirm the effects of the present invention, the strength of the cord, the protrusion of the core filament, the rubber penetration between the strands, the rubber penetration into the strands, and the fatigue resistance were evaluated in Examples 1, 2, and 3. 3, 5 and Comparative Examples 1 to
No. 3 was prototyped and compared.

Here, the cross section of the steel cord 30 for reinforcing rubber articles of Comparative Example 1 is as shown in FIG.
9 is as shown in FIG. 9, and a cross-section of the rubber cord for reinforcing rubber article 34 of Comparative Example 3 is as shown in FIG. 10. Comparative Examples 1-3
Are as shown in Table 1 above.

As shown in FIG. 8, in the steel cord 30 for reinforcing rubber articles of Comparative Example 1, the core filament 26 jumps out due to the difference in the twisting ratio. As shown in FIG. 9, in the rubber cord for reinforcing a rubber article 32 of Comparative Example 2, the gap between the sheath filaments 28 is small.
It can be seen that the permeability of the rubber deteriorates. Further, as shown in FIG. 10, in the rubber cord for reinforcing a rubber article 34 of Comparative Example 3, since the number of the strands 24 is six, the strands 24 cannot be arranged concentrically.

The following are items to be compared. Projection of core filament After the production of the steel cord for reinforcing rubber articles, the steel cord was observed over a length of 100 m in the longitudinal direction, and the presence or absence of projection of the core filament was recorded. Fatigue resistance Bending stress 1 using a Hunter type rotary bending fatigue tester
20 kgf / mm ² , rotation speed 3000 rpm, temperature 20
The total number of revolutions until the steel cord was broken at a temperature of 60 ° C. and a relative humidity of 60% was recorded. As a result, Comparative Example 1 was 10
It is indicated by an index as 0, and the larger the value, the better the fatigue resistance. Rubber permeability The rubber permeability between the strands and in the strands is determined by stripping the rubber on the cord surface from the steel cord for reinforcing rubber articles buried in rubber and pressurized, heated and vulcanized, untwisting each strand unit, and breaking each strand. Observe and record the amount of rubber at the center of the cord.
%, And 100% when completely covered with rubber.

From the results shown in Table 1, the steel cords for reinforcing rubber articles of Examples 1, 2, 3, and 5 to which the present invention was applied were excellent in rubber permeability between the strands and in the strands. From this, it is clear that it has excellent corrosion resistance.

Further, Embodiments 1, 2 and 2 to which the present invention is applied.
The steel cords for reinforcing rubber articles 3 and 5 are Comparative Examples 1 to
It can be seen that the fatigue resistance is much better than that of No. 3.

[0043]

As described above, in the rubber cord for reinforcing a rubber article according to the first aspect, each strand is twisted concentrically, and each strand is surrounded by one core filament and four filaments around the core filament. When the diameter of the core filament and the sheath filament is dc and ds, respectively, the configuration is such that the relationship 1.56 ≦ ds / dc ≦ 1.75 is satisfied. It has an excellent effect of preventing a decrease in resistance, improving the stability of twist, improving the permeability of an elastic body such as rubber, and improving fatigue resistance. Further, when the rubber is embedded in the rubber article and vulcanized, the rubber penetrates well between the filaments, so that the corrosion resistance can be improved and the generation of rust can be suppressed, and the durability of the rubber article can be improved.

Further, since the number of filaments constituting the cord can be increased, the cord strength can be increased.
When the cord strength is not so required, the diameter of the filament can be reduced, so that the fatigue resistance can be improved.

In the steel cord for reinforcing a rubber article according to the second aspect, each strand is concentrically twisted, and each strand is wound with one core filament and five sheath filaments wound around the core filament. When the diameters of the core filament and the sheath filament are dc and ds, respectively, 1.00 ≦ ds
/Dc≦1.10, it is possible to prevent a decrease in productivity, improve the stability of twist, improve the permeability of an elastic body such as rubber, and improve the fatigue resistance.
It has an excellent effect. Further, since rubber is well penetrated between filaments when embedded and vulcanized in a rubber article, the generation of rust can be suppressed and the durability of the rubber article can be improved.

In the steel cord for reinforcing a rubber article according to the third aspect, since the twist direction of the strand and the cord is the same, the contact force when the cord is locally bent and deformed can be reduced, and fretting is reduced. And has an excellent effect of reducing fatigue fracture.

In the steel cord for reinforcing a rubber article according to the fourth aspect, the gap between the sheath filaments of each strand is narrow at the center of the cord and wide at the front side when viewed from the cross section of the cord. This has an excellent effect that the adhesiveness between the wire and the filament is improved, the movement of the filament against repeated bending deformation of the cord is suppressed, and the fatigue resistance can be improved.

In the steel cord for reinforcing a rubber article according to the fifth aspect, the number of strands constituting the steel cord for reinforcing a rubber article is set in the range of 3 to 5, so that a reduction in fatigue resistance is prevented. In addition, it has an excellent effect of preventing a decrease in rubber permeability inside the cord and the strand.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a rubber cord for reinforcing a rubber article according to a first embodiment.

FIG. 2 is a sectional view of a steel cord for reinforcing a rubber article according to a second embodiment.

FIG. 3 is a sectional view of a rubber cord for reinforcing a rubber article according to a third embodiment.

FIG. 4 is a sectional view of a steel cord for reinforcing rubber articles according to a fourth embodiment.

FIG. 5 is a sectional view of a steel cord for reinforcing a rubber article according to a fifth embodiment.

FIG. 6 is a sectional view of a steel cord for reinforcing a rubber article according to a sixth embodiment.

FIG. 7 is a sectional view of a steel cord for reinforcing a rubber article according to a seventh embodiment.

FIG. 8 is a sectional view of a steel cord for reinforcing rubber articles according to Comparative Example 1.

FIG. 9 is a cross-sectional view of a steel cord for reinforcing rubber articles according to Comparative Example 2.

FIG. 10 is a cross-sectional view of a steel cord for reinforcing rubber articles according to Comparative Example 3.

[Explanation of symbols]

 Reference Signs List 10 Steel cord for reinforcing rubber articles 12 Steel cord for reinforcing rubber articles 14 Steel cord for reinforcing rubber articles 16 Steel cord for reinforcing rubber articles 18 Steel cord for reinforcing rubber articles 20 Steel cord for reinforcing rubber articles 22 Steel cord for reinforcing rubber articles 24 Strand 26 core filament 28 sheath filament

Claims (5)

[Claims] 1. A steel cord for reinforcing a rubber article in which each strand is concentrically twisted, wherein each strand has a layered structure in which one core filament and four sheath filaments are wound around the core filament. A steel cord for reinforcing rubber articles, characterized by satisfying a relationship of 1.56 ≦ ds / dc ≦ 1.75, where the diameters of the core filament and the sheath filament are dc and ds, respectively. 2. A steel cord for reinforcing a rubber article in which each strand is concentrically twisted, wherein each strand has a layered structure in which one core filament and five sheath filaments are wound around the core filament. A steel cord for reinforcing rubber articles, wherein the relationship of 1.00 ≦ ds / dc ≦ 1.10. Is satisfied, where the diameters of the core filament and the sheath filament are dc and ds, respectively. 3. The steel cord for reinforcing rubber articles according to claim 1, wherein the strands and the cords have the same twist direction. 4. The steel cord for reinforcing rubber articles according to claim 1, wherein the gap between the sheath filaments of each strand is narrow on the center side of the cord and wide on the front side. The steel cord for reinforcing a rubber article according to any one of the preceding claims. 5. The steel cord for reinforcing rubber articles according to claim 1, wherein the number of strands constituting the steel cord for reinforcing rubber articles is in the range of 3 to 5.