JP3153359B2 - Steel cord for reinforcing rubber articles and cord / rubber composite using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cord / rubber composite such as a rubber hose, a rubber belt and a pneumatic tire, and a steel cord for reinforcing a rubber article used for the cord / rubber composite.

[0002]

2. Description of the Related Art Conventionally, a central basic structure composed of 1 to 4 steel filaments and at least one coaxial layer composed of a large number of steel filaments around the central basic structure are arranged in the same direction and at the same pitch. Various steel cords having a compact twisted structure have been proposed.

[0003]

When a steel cord in which the central basic structure and the coaxial layer are twisted in the same direction and at exactly the same pitch is used for a belt ply, carcass ply, chafer or the like of a radial tire, , The filament of the central basic structure jumps out from the end of the cord, and in some cases, is exposed to the outside of the tire.

Further, in the case of a steel cord in which the central basic structure and the coaxial layer are twisted at different pitches, the steel filament of the central basic structure and the steel filament of the coaxial layer have many point contacts, and are inferior in fretting resistance. There is a problem with corrosion fatigue.

[0005] In view of the above facts, the present invention is for reinforcing a rubber article capable of preventing the steel filament disposed inside the outermost layer from jumping out when repeated bending input acts and preventing corrosion fatigue. It is an object of the present invention to provide a cord / rubber composite using a steel cord and a steel cord for reinforcing rubber articles.

[0006]

According to the first aspect of the present invention,
Steel for reinforcing rubber articles, comprising: a central basic structure composed of 1 to 4 steel filaments having the same diameter; and at least one coaxial layer composed of a plurality of steel filaments arranged around the central basic structure. In the cord, the outer diameter d _S of the steel filament of the coaxial layer is smaller than the outer diameter d _C of the steel filament of the central basic structure, and d _C / d _S is 1.03 to 1.25. For the 1 to 10 pitches of the twist of the steel filament one inner side of the outer coaxial layer, the outermost coaxial layer is shifted so that the steel filament of the outermost coaxial layer shifts to the position of the adjacent steel filament in the circumferential direction. as characterized in that twisted in the same direction and one inner steel filaments than steel filaments and the outermost concentric layers of coaxial layers That.

[0007] A cord-rubber composite according to the second aspect of the present invention is characterized by using the steel cord for reinforcing a rubber article according to the first aspect.

[0008]

According to the steel cord for reinforcing a rubber article of the present invention, the steel filament of the outermost coaxial layer extends in the circumferential direction with respect to 1 to 10 pitches of the twisting pitch of the steel filament one inside the outermost coaxial layer. The steel filament of the outermost coaxial layer and the steel filament one inner side of the outermost coaxial layer are twisted in the same direction so that a shift occurs to the position of the adjacent steel filament.

For this reason, the form of contact between the steel filament of the outermost coaxial layer and the steel filament one inner side of the outermost coaxial layer is not only a form of line contact but also a part of point contact. Therefore, the steel filaments of the outermost coaxial layer intersect and press the outer side of the steel filament one inner side of the outermost coaxial layer by point contact. Therefore, when the steel cord for rubber article reinforcement is subjected to bending deformation, the protrusion of the steel filament inside the outermost coaxial layer can be prevented by the contact pressure of the point contact portion.

Further, the outer diameter d _S of the steel filament of the coaxial layer is made equal to the outer diameter d _S of the steel filament having the central basic structure.
Less than _C, by which a 1.03 to 1.25 to d _C / d _S, by the contact pressure of the steel filaments of the coaxial layer is reduced, fretting is prevented by steel filaments of the coaxial layer You.

The steel filament of the outermost coaxial layer is shifted to the position of the adjacent steel filament in the circumferential direction at less than one twist pitch of the steel filament one inner side of the outermost coaxial layer. When the steel filament of the outermost coaxial layer is twisted with the steel filament one inner side of the outermost coaxial layer, Increase in the number of point contact points with the steel filament of the outermost coaxial layer is not preferable because fretting occurs between the steel filament of the outermost coaxial layer and the steel filament one inner side of the outermost coaxial layer (point contact And the fretting becomes deeper).

In addition, the steel filament of the outermost coaxial layer is shifted at a pitch larger than 10 pitches of the twist of the steel filament one inner side of the outermost coaxial layer to the position of the steel filament adjacent in the circumferential direction. When the steel filament of the outermost coaxial layer is twisted with the steel filament one inner side of the outermost coaxial layer, the frequency of switching to the position of the adjacent steel filament decreases, and the point contact It is not preferable because the number of locations is reduced and the effect of preventing the steel filament inside one side from the outermost coaxial layer from jumping out is reduced, particularly when a steel cord for reinforcing rubber articles is used for a belt of a radial tire or the like. The outer coaxial layer shows the outer appearance of the steel cord for reinforcing the rubber article. There may be no exchange between the base and the inner sheath (because a narrow belt may have a length of less than 10 pitches per belt), and may be one more than the outermost coaxial layer. In some cases, the effect of preventing the inner steel filament from jumping out is not obtained.

[0013]

FIG. 1A and FIG. 1 show a first embodiment of the present invention.
A description will be given according to (B).

As shown in FIG. 1A, a steel cord 100 for reinforcing a rubber article according to the present invention comprises a core 20 as a central basic structure composed of 1 to 4 steel filaments having the same diameter, and a periphery of the core 20. It has a sheath 22 of a coaxial layer made of steel filaments of a plurality of arranged in the outer diameter d _S of the steel filaments of the sheath 22
Is smaller than the outer diameter d _C of the steel filament of the core 20.
And d _C / d _S is 1.03 to 1.25.
You.

The core 20 and the sheath 22 are in the same direction.
Twisted together, the shift to the position of the steel filaments steel filaments of the outermost of the coaxial layer with respect to 1 to 10 pitches of the twist pitch of the immediately inner steel filaments than the outermost concentric layers are adjacent in the circumferential direction So that the outermost coaxial layer and the steel filament one layer inside the outermost coaxial layer are in the same direction so that
It is twisted. That is, the rubber composition article-reinforcing steel cord 100 according to the present invention, the twist pitch of the immediately inner steel filaments from the outermost coaxial layers, the twist pitch of the steel filaments of the outermost coaxial layer are substantially the same
Although the pitch is 1 to 10 pitches of the twisting pitch of the steel filament one inside from the outermost coaxial layer
Steel filament of the outermost coaxial layer is adjacent in the circumferential direction
To the position of the steel filament to be
Only, both pitch features a slightly different exactly
You.

The steel filaments of the outermost coaxial layer are adjacent to each other in the circumferential direction within a range corresponding to a twist pitch of 3 to 10 pitches of the steel filament one inner side of the outermost coaxial layer. It is further preferable that the steel filament of the outermost coaxial layer and the steel filament one inner side of the outermost coaxial layer are twisted in the same direction so that the position is shifted.

The rubber cord 100 for reinforcing a rubber article according to this embodiment has a core 20 as a central basic structure composed of three steel filaments 1 to 3, and nine steel filaments 4 to 4 around the core 20. A sheath 22 as a coaxial layer made of 12 is provided. Here, the outer diameter d _S of the steel filaments 4 to 12 of the sheath 22 is 0.225 mm, and the outer diameter d _C of the steel filaments 1 to 3 of the core 20 is 0.240 mm. In the present embodiment, d _C / d _S is about 1.07.

The core 20 and the sheath 22 are twisted in the same direction (S direction). For three twisted pitches of the core 20, the sheath 22 is
A, an inner sheath 22B adjacent from the inner sheath 22A, an outer sheath 22A adjacent from the inner sheath 22B,
Outer sheath 2 adjacent to outer sheath 22A
The twist pitch of the sheath 22 is set so as to be switched once to 2A (for example, the state of FIG. 1A changes from the state of FIG. 1A to the state of FIG. 1B).

Further, the steel cord 100 for reinforcing a rubber article of the present embodiment has an outer diameter of 0.1
A 5 mm spiral filament 24 spirally surrounds the Z direction at a pitch of 3.5 mm.

Next, the operation of this embodiment will be described. The steel cord 100 for reinforcing a rubber article of the present embodiment has a sheath 2
2 is replaced once for the three pitches of the twist of the core 20 by the inner sheath 22B adjacent to the outer sheath 22A, the outer sheath 22A adjacent to the inner sheath 22B, and the outer sheath 22A adjacent to the outer sheath 22A. Therefore, the form of contact between the filaments 4 to 12 of the sheath 22 and the filaments 1 to 3 of the core 20 is not limited to the form of only line contact,
Some also have point contacts.

That is, the filaments 1 to 3 of the core 20
When the filament 4 to 12 of the sheath 22 crosses and presses the outside, the contact pressure increases at the point contact portion as compared with the line contact portion. Of the core 20 can be prevented. As described above, the steel cord 100 for reinforcing rubber articles of the present embodiment can prevent the core 20 from jumping out while making use of the corrosion fatigue resistance, which is an advantage of the compact cord.

The steel filament 1 of the core 20
Steel filament 4 of the sheath 22 as compared with
By reducing the wire diameter of 12, the contact pressure between the steel filaments 4 to 12 of the sheath 22 is reduced, and fretting between the steel filaments 4 to 12 of the sheath 22 is prevented.

It is to be noted that the steel filament of the outermost coaxial layer is shifted from the steel filament of the outermost coaxial layer so that the steel filament of the outermost coaxial layer is shifted to the position of the adjacent steel filament in the circumferential direction at less than one pitch of the twist of the core 20. When a steel filament one inner side of the coaxial layer is twisted, the filaments 1 to 3 of the core 20 and the sheath 22 are twisted.
The point of contact with the filaments 4 to 12 of the core 20 increases, and the intersection angle between the filaments 1 to 3 of the core 20 and the filaments 4 to 12 of the sheath 22 becomes tight. Fretting occurs between 4 and 12 (point contact points increase, fretting also increases), and corrosion fatigue tends to increase, which is not preferable.

Also, the outermost coaxial layer steel filaments are shifted from the outermost coaxial layer steel filaments so that the steel filaments of the outermost coaxial layer are displaced in the circumferential direction at a pitch larger than 10 twists of the core 20 to the position of the adjacent steel filaments. When the steel filament inside the outermost coaxial layer is twisted one inside, the frequency of switching to the position of the adjacent steel filament is reduced, the number of point contacts is reduced, and the core 20 is prevented from jumping out. In particular, when the steel cord 100 for reinforcing rubber articles is used for a belt of a radial tire, the steel cord 100 for reinforcing rubber articles 100 is not preferable.
Looking at the hits, there is a case where the positions of the adjacent steel filaments are not switched (because the length of one belt may be less than 10 pitches in a narrow belt), and the effect of preventing the core 20 from jumping out. May not appear.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. 2 (A) and 2 (B). The same components as those of the first embodiment are denoted by the same reference numerals,
The description is omitted.

As shown in FIG. 2A, the steel cord 100 for reinforcing a rubber article of the present embodiment has a steel cord 32 composed of six steel filaments 32 to 37 around a core 20 composed of one steel filament 31. One sheath 26 is provided. Around the first sheath 26, a second sheath 28 including twelve steel filaments 38 to 49 is provided.
Are arranged.

The first sheath 26 and the second sheath 28 are twisted in the same direction (S direction), and the twist pitch of the first sheath 26, which is one inside the outermost coaxial layer, is one.
At 10 to 10 pitches, the steel filaments 38 to 49 of the second sheath 28, which is the outermost coaxial layer, are replaced once by the inner sheath 22B adjacent to the outer sheath 22A or the outer sheath 22A adjacent to the inner sheath 22B. The twist pitch of the outermost coaxial layer is set (for example, the state of FIG. 1A is changed to the state of FIG. 1B). Further, the second sheath 2
On the outer periphery of 8, a spiral filament 24 spirally surrounds the Z direction.

In the steel cord 100 for reinforcing a rubber article of the present embodiment, the outermost second sheath 28 has a twist pitch of 1 to 10 pitches of the first sheath 26 which is one inner side of the outermost coaxial layer. Inner sheath 22B or inner sheath 2 adjacent to outer sheath 22A
Since the outer sheath 22A is replaced once with the adjacent outer sheath 22A, the second sheath 28 crosses the first sheath 26 and presses the first sheath 26 and the core 20, which is the same as in the first embodiment. The core 20 is prevented from jumping out when subjected to bending deformation.

(Test Example) The steel cord 100 for reinforcing a rubber article of the present invention was used for a carcass and a belt of a pneumatic radial tire, and the results of confirming the effect of preventing steel filament from jumping out and preventing corrosion fatigue are shown in Table 1 below. To Table 3 below.

Table 1 shows that three types of steel cords for reinforcing rubber articles according to the present invention and five types of steel cords for reinforcing rubber articles according to comparative examples were used to form carcass plies, and these carcass plies (the number of cords to be driven: Eight types of pneumatic radial tires (tire size 10.00R2014PR) using 17.5 tires / 5 cm) were prototyped, and the results of corrosion fatigue test and core protrusion check were shown. In each, three types of steel cords for reinforcing rubber articles according to the present invention and five types of steel cords for reinforcing rubber articles according to comparative examples are respectively made into carcass plies,
These carcass plies (number of cords to be driven: 1
Eight prototypes of pneumatic radial tires (tire size 10.00R20) using 3.6 tires / 5cm) were tested, and the results of corrosion fatigue test and core protrusion check were shown. Reference numeral 3 denotes a belt (three kinds of steel cords for reinforcing rubber articles according to the present invention and five kinds of steel cords for reinforcing rubber articles according to comparative examples) each having a belt (number of cords driven: 19.7 / 5 cm, cord angle with respect to the equatorial plane). 18 °) and a pneumatic radial tire (tire size 10.00R20TB) using these belts
R) shows eight prototypes, the results of corrosion fatigue test and the results of core protrusion check.

Here, the corrosion fatigue resistance is determined by arranging a tube inside the inner liner of the tire when assembling the rim of the test tire, and setting the tube between the inner liner and the tube.
0 ml of water was sealed, and each test tire was evaluated for its life (running distance) until a cord break (CBU) failure in a drum test. The evaluation value was expressed as an index and calculated by the following equation (1). The test tires had an internal pressure of 8 kg / cm ² and applied a JIS 100% load. The traveling speed is 60 km / h.

[0032]

(Equation 1)

The protruding core was checked visually by mounting the test tire on an actual vehicle and running it for 160,000 km, cutting out the ply end and the belt end of the test tire running for 160,000 km.

Here, the twist structure, twist direction, wire diameter of steel filament, twist pitch, and frequency of sheath replacement of the steel cord for reinforcing rubber articles used in the test (the twist of the steel filament one inside the outermost layer). The frequency at which the outermost steel cord is replaced with the position of the adjacent steel cord at every pitch is shown in the table.

In the present invention, the outermost coaxial layer is made of steel.
The steel foil one layer inside the filament and the outermost coaxial layer
Filament (sheath filament and core filament)
Or the filament of the second sheath and the filament of the first sheath
The twist pitches of the filaments are not exactly the same, but the current measurement method does not cause a difference in numerical values, so the twist pitches in the table are approximate values.

Further, Comparative Examples 2 to 5, Comparative Examples 12 to 15,
The cross-sectional shape of the steel cord for reinforcing rubber articles of Examples 1 to 3 and Examples 7 to 9 is as shown in FIG. 1A, and the steel for reinforcing rubber articles of Comparative Examples 7 to 10 and Examples 4 to 6 is shown. The cross-sectional shape of the cord is as shown in FIG. The cross-sectional shape of the steel cord for reinforcing rubber articles of Comparative Example 1 is as shown in FIG. 3, and the cross-sectional shape of the steel cord for reinforcing rubber articles of Comparative Example 6 is as shown in FIG.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

From the test results shown in Tables 1 to 3, the steel cord for reinforcing a rubber article of the present invention is excellent in core protrusion prevention and corrosion fatigue resistance, and is pneumatic using the steel cord for reinforcing a rubber article of the present invention. It is clear that the durability of the radial tire is excellent.

In the steel cord for reinforcing rubber articles of the above embodiments, the spiral filament 24 is provided on the outer periphery. However, in the present invention, it is not always necessary to provide the spiral filament 24, and even if the spiral filament 24 is not provided. Good.

The steel cord for reinforcing rubber articles of the present invention can be applied not only to carcass plies and belts of tires, but also to reinforcement of rubber products such as rubber hoses and rubber belts.

[0043]

As described above, the steel cord for reinforcing rubber articles according to the first aspect of the present invention has the above-described structure, and therefore has an excellent effect of preventing the core from popping out and corrosive fatigue when repeatedly subjected to bending input. Since the cord / rubber composite according to the second aspect uses the steel cord for reinforcing a rubber article according to the first aspect, it has an excellent effect that durability against repeated bending input is improved.

[Brief description of the drawings]

1A is a cross-sectional view of a steel cord for reinforcing a rubber article according to a first embodiment of the present invention, and FIG.
It is sectional drawing of another part of the steel cord for rubber articles reinforcement shown in (A).

FIG. 2A is a cross-sectional view of a steel cord for reinforcing a rubber article according to a second embodiment of the present invention, and FIG.
It is sectional drawing of another part of the steel cord for rubber articles reinforcement shown in (A).

FIG. 3 is a sectional view of a rubber cord for reinforcing a rubber article of Comparative Example 1.

FIG. 4 is a cross-sectional view of a steel cord for reinforcing rubber articles of Comparative Example 6.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Steel cord for reinforcing rubber articles 1 to 12 Steel filament 31 to 49 Steel filament 20 Core (center basic structure) 22 Sheath (coaxial layer) 26 First sheath (coaxial layer) 28 Second sheath (coaxial layer) 22A Outer sheath 28A Outer sheath 22B Inner sheath 28B Inner sheath

Claims (2)

(57) [Claims] 1. A central basic structure including one to four steel filaments having the same diameter, and at least one coaxial layer including a plurality of steel filaments arranged around the central basic structure. In the steel cord for reinforcing rubber articles, the outer diameter d _S of the steel filament of the coaxial layer is smaller than the outer diameter d _C of the steel filament of the central basic structure, and d _C / d _S is 1.03 to 1.25. In addition, the steel filament of the outermost coaxial layer is shifted to the position of the adjacent steel filament in the circumferential direction for 1 to 10 pitches of the twist of the steel filament one inner side of the outermost coaxial layer. as such, Awasetako twisted in the same direction and one inner steel filaments than steel filaments and the outermost concentric layers of the outermost coaxial layer Steel cord for reinforcement of rubber articles according to claim. 2. A cord / rubber composite comprising the steel cord for reinforcing rubber articles according to claim 1.