JP2002161489A - Metallic cord for reinforcing rubber article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic cord of layer-laid structure improved in rubber penetrability and fatigue resistance. SOLUTION: This metallic cord has such a layer-laid structure as to have a core 2 consisting of a single filament bundle 5 formed of 6-12 filaments Fa and a sheath 3 consisting of 8-15 filaments Fb disposed around the core 2. The filament bundle 5 comprises two-dimensionally preformed filaments 6 and non-preformed filaments 7, and the two-dimensional wavy form of the filaments 6 is made to a three-dimensional one by mutually laying the filament bundle 5 with the sheath 3 while twisting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal cord used as a reinforcing material for a rubber article such as a pneumatic tire, and more particularly to a metal cord having a compact structure that allows rubber to easily penetrate into the cord to improve corrosion resistance. The present invention relates to a metal cord for reinforcing rubber articles having improved fatigue resistance.

[0002]

2. Description of the Related Art For example, in a metal cord used for a pneumatic tire, in order to increase the cord tensile strength per cord diameter and obtain good fatigue resistance, filaments having the same diameter are closely packed. The arranged layer twist structure is widely adopted. However, such a close-packed layered structure has a small gap between filaments in the sheath,
A cavity is easily formed without rubber sufficiently entering the cord, and moisture easily penetrates into the cavity to corrode the cord.

[0003] Therefore, by applying a two-dimensional corrugation to the core filament in the layered structure and specifying the relationship between the molding shape and the filament diameter,
Improving the degree of penetration of rubber into the inside of a cord has been proposed, for example, in JP-A-9-31875.

[0004]

However, according to the above proposal, the filament of the molded core is twisted with the sheath without being twisted. Therefore, even in the cord state, the filament of the two-dimensional molding state is obtained. Remains. Therefore, although there is an apparent gap in the core, there is a problem that the effect of improving rubber penetration is small.

Accordingly, the present invention is based on the fact that a core is formed by a single filament bundle including a two-dimensional shaped filament and a non-shaped filament, and the filament bundle is twisted with a sheath while being twisted. It is an object of the present invention to provide a metal cord for reinforcing a rubber article, which can make a two-dimensional wave three-dimensional in a cord, and can sufficiently secure rubber permeability while reducing the cord diameter.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a core comprising one filament bundle composed of 6 to 12 filaments, and a core arranged around the core. A layer-twisted structure comprising a sheath of 8 to 15 filaments, wherein the core is shaped into a two-dimensional wavy pattern in which a wave peak and a valley are repeated before being twisted. The core includes a filament and an unshaped filament, and the core is twisted with the sheath while twisting the filament bundle, whereby the shaping of the shaped filament is made three-dimensional in the core by the twist.

In the invention according to claim 2, the core has a replacement portion in which the position of the filament is switched between the inside and the outside in the filament bundle, and the replacement portion has a number of 5 times or more per 1 m of cord length. It is characterized by doing.

According to a third aspect of the present invention, the filament of the core has a wire diameter d of 0.15 to 0.30 mm and has substantially the same diameter as the filament of the sheath.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described.
This will be described together with the illustrated example. FIG. 1 is a sectional view showing an example of a metal cord for reinforcing a rubber article of the present invention.

In FIG. 1, a metal cord 1 for reinforcing a rubber article (hereinafter referred to as a metal cord 1) has a core 2 formed by one filament bundle 5 composed of 6 to 12 filaments Fa, and One more sheath 3 consisting of 8 to 15 filaments Fb wound around
And a layer-twisted structure. In this example, an 8 + 12 configuration in which the core 2 is composed of eight filaments Fa and the sheath 3 is composed of 12 filaments Fb is illustrated.

The filament bundle 5 is formed as shown in FIG.
In a state before being twisted, a two-dimensional corrugated molding filament 6 that repeats a wave peak Y1 and a valley Y2, and an unmolded non-molding filament 7
It is composed of

In the present embodiment, the molding filament 6 is
Although a zigzag shape in which a straight portion Y3 is interposed between the peak portion Y1 and the valley portion Y2 is illustrated, a sine curve shape or the like consisting of only a curve may be used. Like this 2
Dimensional shaping has advantages in that it is easier to process, has higher dimensional accuracy, is more stable, and is easier to handle than three-dimensional shaping such as a spiral shape. It is also advantageous in forming the cord more compactly.

In the present invention, as shown in FIG. 3, the core 2 is formed by twisting a filament bundle 5 in which the filaments Fa (that is, the molding filament 6 and the non-molding filament 7) are aligned. The metal cord 1 is formed by twisting the sheath 3, that is, winding the filament Fb around the core 2.

As described above, in the core 2, since the filament bundle 5 is twisted, the two-dimensional wave in the molding filament 6 is three-dimensionally formed in the core by the twist. Therefore, while the core 2 is compact, a sufficient gap can be stably secured between the filaments Fa of the core 2 and between the filaments Fb of the sheath 3 surrounding the core, and the degree of penetration of rubber (rubber permeability ) Can be greatly improved. In addition, by securing such a gap, fretting (a phenomenon in which relative fine sliding occurs repeatedly between filaments and wear) is suppressed, so that fatigue resistance is further improved.

It is preferable to arrange 2 to 8 shaping filaments 6 in the filament bundle 5 for rubber permeability.

Here, the three-dimensional conversion of a two-dimensional wave is described as follows. That is, as shown conceptually in FIG. 4A, when a twist K1 is added to the filament bundle A, the twist K1 is reflected as a similar twist K2 on each filament B. At this time, when the filament bundle A includes the molding filament B1, as schematically shown in FIG. 4B, each molding filament B1 is connected to the twist K2.
Is twisted around the center, and the two-dimensional wave becomes three-dimensional.

Incidentally, if there is no twist and two-dimensional waves remain,
The molding filaments 6 do not overlap in a two-dimensional plane or entanglement of the filaments is lost, so that it is difficult to maintain a gap, and the effect of improving rubber penetration cannot be sufficiently exhibited.

Next, the reason why the metal cord 1 has the layer twist structure is that the number of filaments with respect to the cord diameter can be increased when forming the cord, thereby increasing the cord strength. This is because the effect of reinforcing the rubber article can be enhanced, and the filament can be made thinner to improve the bending fatigue property.

The number of filaments Fa used for the core 2 is 6 to 12, and the number of filaments Fa used for the sheath 3 is
It is necessary that the number of b is 8 to 15, and if it is out of this range, the balance between the core 2 and the sheath 3
Problems arise in strength, fatigue resistance and the like.

The filament Fa and the filament F
It is preferable that b have the same diameter as each other, so that the wire drawing process can be shared and the cord can be economically manufactured.

At this time, the number of filaments is optimized,
In order to obtain excellent cord strength and bending fatigue properties, the filament diameters of the filaments Fa and Fb are set to 0.15 to 0.30.
mm. The wire diameter d is 0.15
If it is less than mm, there is a problem that it is too thin and disadvantageous in terms of cord strength, and that the type is easily restored to its original state. Conversely, if it exceeds 0.30 mm, the flexibility of the cord is inferior,
Also, the fatigue resistance of the cord is deteriorated.

In this embodiment, as shown in FIGS. 5A and 5B, the core 2 has a replacement portion 9 in which the position of the filament Fa is switched between the inside and the outside in the filament bundle 5. ing. In the figure, the filaments Fa are numbered 1 to 8 to distinguish them. In this example, the filament Fa1 and the filament Fa8 are switched inside and outside. The formation of the replacement portion 9 is preferable in preventing entanglement between the filaments Fa and preventing the filaments Fa from being united and preventing the filaments from becoming uneven. In order to prevent this variation, it is preferable that the replacement part 9 is formed at five or more locations per 1 m of the cord length.

With regard to the shaping of the shaping filament 6, as shown in FIG. 2, before being twisted, the wave pitch Pw and wave height h are set to 3.
It is preferable that the thickness is in the range of 0 to 9.0 mm and 0.20 to 0.80 mm, whereby the mold can be economically formed and excellent rubber permeability can be secured. If the wave pitch Pw is smaller than 3.0 mm or the wave height h is larger than 0.80 mm, the amount of shaping work increases and the working cost increases. It causes a decline. Conversely, if the wave pitch Pw is larger than 9.0 mm or the wave height h is smaller than 0.20 mm, the molding is too small, and the effect of improving the rubber permeability cannot be sufficiently exhibited. The wave pitch Pw is a distance in the longitudinal direction between the peaks Y1, Y1, and the wave height h is a distance in the amplitude direction between the peak Y1 and the valley Y2.

Next, as shown in FIG. 3, the twist pitch Pn when twisting the filament bundle 5 to convert a two-dimensional wave into a three-dimensional wave.
Is preferably in the range of 5.0 to 600.0 mm and 5.0
If it is smaller than mm, the apparent outer diameter of the cord will be smaller,
On the other hand, if it is larger than 600.0 mm, the three-dimensional effect is reduced, and the effect of improving the rubber permeability is not fully exhibited in any case.

The twist pitch Py of the sheath 3 twisted around the core 2, that is, the winding pitch of the filament Fb, is preferably in the range of 5.0 to 30.0 mm. If the twist pitch Py is smaller than 5.0 mm, the initial elongation of the cord is large and the reinforcing effect is poor, and the wire length between the filaments Fa and Fb is greatly different. Strength tends to decrease. When the twist pitch Py exceeds 30.0 mm, the filaments are apt to be uneven, and the shape retention of the cord deteriorates.

The twist direction of the sheath 3 may be the same as or different from the twist direction of the filament bundle 5.
Generally, the twist pitch Pn is preferably set to be larger than the twist pitch Py from the viewpoint of maintaining the cord strength.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment, but may be implemented in various forms.

[0028]

EXAMPLES Based on the specifications in Table 1, a trial production of a metal cord having a layered structure was conducted, and for each of the test cords, the rubber permeability, fatigue resistance, and the variation when the cord was cut were tested. Are shown in Table 1 above. In addition,
FIG. 6 shows a cross-sectional shape of the metal cord used in Comparative Example 1.

(1) Rubber permeability: Test cords are arranged in parallel in an unvulcanized rubber sheet at intervals and embedded.
Vulcanization was carried out under heat and pressure. Take out the test cord from the obtained vulcanized rubber sheet, remove the rubber as much as possible from the surface, disassemble the test cord, and reduce the length of the portion of the cord where the rubber is filled into the voids. Measured over 10 cm, the ratio of this length to the total length is defined as the rubber permeability. The above measurement is performed for ten codes, and the average value is used as the measured value of the code.

(2) Fatigue resistance: The cured rubber sheet was repeatedly bent until the cured rubber sheet was broken by a repeated bending fatigue test (Dematia method) according to JIS L1017. The solid number at break was measured. The above measurement was performed on ten rubber sheets, and the average value was evaluated by an index notation with the value of Comparative Example 1 being 100. A higher value indicates higher fatigue resistance.

(3) Variation when code is cut:
The formed metal cord was cut, and at that time, the state of variation of the cord was visually inspected.

[0032]

[Table 1]

[0033]

As described above, the present invention provides a core comprising a two-dimensional shaped filament and a non-shaped filament.
The filament bundle is twisted with the sheath while being twisted. Therefore,
The two-dimensional wave of the molded filament can be made three-dimensional in the cord, the gap between the filaments can be sufficiently secured while the cord diameter is reduced, and the rubber permeability can be greatly increased. Also, fatigue resistance can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a metal cord according to an embodiment of the present invention.

FIG. 2 is a side view showing a molding shape of a molding filament in a state before twisting.

FIG. 3 is a diagram illustrating a process of forming a core.

FIGS. 4A and 4B are diagrams illustrating three-dimensional conversion of a two-dimensional wave by torsion.

FIGS. 5A and 5B are cross-sectional views of a core illustrating a replacement part.

FIG. 6 is a sectional view showing a metal cord of Comparative Example 1 used in the test of Table 1.

[Explanation of symbols]

 Reference Signs List 2 core 3 sheath 5 filament bundle 6 shaped filament 7 non-shaped filament 9 replacement part Fa, Fb filament Y1 peak Y2 valley

Continued on the front page (72) Inventor Attack Toda 3-6-9, Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo F-term (reference) in Sumitomo Rubber Industries, Ltd. 3B153 AA13 AA19 AA34 BB13 CC52 FF12 FF16 GG05 GG07 GG40

Claims (3)

[Claims] 1. A layer-twisted structure comprising a core consisting of one filament bundle consisting of 6 to 12 filaments and a sheath consisting of 8 to 15 filaments arranged around the core, The core, before being twisted, includes a shaped filament and a non-shaped filament that are shaped in a two-dimensional wave shape that repeats peaks and valleys of the wave, and the core twists the filament bundle while twisting the filament bundle. A metal cord for reinforcing rubber articles, characterized in that the twist of the shaping filament is made three-dimensional in the core by twisting with a sheath. 2. The core according to claim 1, wherein the core has a replacement portion in which the position of the filament is switched between the inside and the outside in the filament bundle, and the replacement portion is provided five times or more per 1 m of cord length. The metal cord for reinforcing a rubber article according to claim 1. 3. The core filament has a wire diameter d of 0.3.
The metal cord for reinforcing a rubber article according to claim 1 or 2, wherein the metal cord has a diameter of 15 to 0.30 mm and substantially the same diameter as the filament of the sheath.