JP2596347Y2 - Steel cord for reinforcing rubber products - Google Patents

Description

[Detailed description of the invention]

[0001] The present invention relates to a steel cord for reinforcing rubber products used as a reinforcing material for rubber products such as automobile tires and conveyor belts, and relates to a multilayered steel cord having a core element wire and a side element wire. is there.

[0002]

2. Description of the Related Art Generally, steel cords of this kind are used as reinforcing materials for rubber products such as automobile tires, conveyor belts, etc., in which a large number of steel cords are covered in parallel in a straight line. . Therefore, indispensable conditions for steel cord are not only excellent mechanical strength, but also good chemical adhesion with rubber material and good penetration of rubber material into steel cord. ,. That is, in order for the steel cord to sufficiently serve as a reinforcing material for a rubber product, it must be a complete composite with the rubber material.

[0003] A conventional steel cord has a so-called closed twist structure, such as a cross-sectional structure shown in Figs. 2 (a) and 2 (b), in which nine to twelve element wires are closely adhered and twisted. This type of steel cord S has a hollow portion A scattered inside the cord and the individual wires are completely adhered to each other. Therefore, when forming the steel cord as a composite sheet using a rubber sheet, The material does not penetrate into the above-mentioned hollow portion, cannot completely cover the periphery of each strand, and cannot cover the outer periphery of the cord to form a complete composite sheet with the rubber material.

[0004] Therefore, in a rubber product using the steel cord, for example, an automobile tire, the rubber material and the steel cord are not sufficiently adhered to each other, and the rubber material and the steel cord are separated when the automobile is running, a so-called separation phenomenon. Causes significant impairment of the function of the tire, as well as the moisture in the rubber material and the moisture penetrating from the cuts in the tire reach the interior of the cord and propagate in the longitudinal direction of the cord, corroding the steel cord, The mechanical strength will be greatly reduced.

For this reason, recently, a so-called tight-twisted open structure steel cord has been proposed in which a rubber material is twisted while providing a gap between the wires so that the rubber material can enter between the wires. . These steel cords O
As shown in FIGS. 3 (a) and 3 (b), the diameter of the core strand or the core strand is made larger than the conventional one or the side strand is made smaller in diameter than the conventional one as shown in FIG. A gap C is provided between them.

[0006]

In the tight twisted steel cord having an open structure, in order for the rubber material to sufficiently penetrate between the individual wires and the inside of the cord,
The gap between each strand should be large enough for the rubber material to enter,
That is, the thickness needs to be 0.02 mm or more. Moreover, in the steel cord O having the structure shown in FIG. 3 in which two layers are twisted, the gap is required also in the inner layer.

However, if the gap C is sufficiently provided between the strands, the twist structure tends to be unstable during the production of the steel cord, and the strands may be shifted or the strand may be twisted. It becomes uneven in the longitudinal direction. further,
In the case of two-layer twisting, since the wires arranged on the inner layer receive more pressure than the outer layer, it is very difficult to provide a necessary gap between the wires on the inner layer. For this reason, the quality of the tight twisted open twisted steel cord cannot be sufficiently satisfied.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and a rubber material surely penetrates between the strands to form a complete composite. An object of the present invention is to provide a steel cord for reinforcing rubber products which does not easily generate fretting wear and has excellent rigidity and fatigue.

[0009]

To achieve SUMMARY OF to the above objects, rubber reinforcing steel cord of the present invention is, in the center, the outer diameter of the apparent _{d 0 = 1.08d 1 ~1.30d 1 (} d 1:
1 Shinmotosen (Shinmotosen diameter d ₁ = 0.20~0.40mm) having a habit substantially spiral small a Shinmotosen diameter)
Are arranged, and six side strands are arranged around the
(P = 6 to 20 mm), in a 1 + 6 steel cord twisted together, the substantially spiral habit of the core wire has a pitch P ₁ = 0.2 P to 0.7 P, and the wire diameter d of the core wire. The ratio of ₁ to the wire diameter d _{2 of the} side strand is d ₁ / d ₂ = 1.
1 to 1.4.

By the way, the numerical limitation in the above configuration is a result obtained by many experiments, and the reason is as follows.

If the wire diameter d ₁ of the core element wire is too small, the mechanical strength is inferior. If the wire diameter d ₁ is too large, the flexibility is inferior and the cord diameter increases. Therefore, the wire diameter d ₁ is preferably in the range of 0.20 to 0.40 mm. .

[0012] substantially the pitch P ₁ habit spiral of small Shinmotosen is less than 0.2 times the twisting pitch P, it will be added to excessive plastic deformation Shinmotosen during imprint, broken Shinmotosen It becomes easier and productivity decreases. On the other hand, if it is larger than 0.7 times, the gap between the wires decreases due to the tensile force due to the flow of the rubber material during molding of the rubber product or the ironing force applied to the cord surface, and the rubber material is not sufficiently mixed , P ₁ = 0.2P to 0.7P. In addition,
Cord twist pitch P of steel cord is twist stability,
It is preferably 6 mm to 20 mm from the viewpoint of productivity.

The apparent outer diameter d ₀ is 1.08 of d ₁ .
If it is smaller than twice, even if a rubber material having good fluidity is used, penetration into the inside of the steel cord during pressure vulcanization is not sufficient, and if it is larger than 1.30 times, the stability of twist becomes poor,
Not only the fatigue resistance is lowered, encoding elongation at extremely low load is increased, have poor handling properties, d ₀ = 1.0
Was the 8d ₁ ~1.30d _1.

Here, a substantially spiral small habit is not limited to a precise spiral shape, but also a simple wavy shape can provide substantially the same effect, and thus includes such a shape.

The reason why the wire diameter ratio d ₁ / d ₂ = 1.1 to 1.4 between the central core wire and the six side wires around the core wire is that the wire diameter ratio is 1.1. If it is smaller than 1, the width of the gap between the wires will decrease, and the desired rubber material cannot be mixed sufficiently. If it is larger than 1.4, the shape will be poor and the core wire will protrude. This is because it occurs. It is conceivable to reduce the wire diameter ratio and increase the apparent outer diameter d ₀ , but in this case, a substantially spiral small habit is easily deformed by the tension applied to the steel cord at the time of molding as a rubber product, and the rubber It is not preferable because infiltration becomes difficult.

[0016]

When the rubber cord is sandwiched between two rubber sheets and vulcanized under pressure using the rubber cord for reinforcing a rubber product having the above-described structure, the rubber material is formed into a substantially spiral-shaped small wire and a side wire. It penetrates into the minute gaps between the wires and the entire wire is almost completely covered with the rubber material to form a complete composite with the rubber.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is an explanatory sectional view showing an embodiment of the present invention. The steel cord 1 has a pitch P ₁ = 4.5 m.
m, ₁ having a diameter d ₁ = 0.34 mm having a substantially spiral small habit having an apparent outer diameter d ₀ = 0.38 mm.
Core strands 2 and a twist pitch P = 18.0 m around the core strands 2
m, S, and six side strands 3 having a wire diameter d ₂ = 0.30 mm.

By the way, as shown in Japanese Patent Publication No. 63-63293, the small spiraling of the core wire 2 is performed by a rotating device using the supplied wire as an axis. the outer diameter D ₀ of the apparent pitch P ₀ habit suitable by those that confer. At this time, in order to provide a suitable habit pitch P ₀ and an apparent outer diameter D ₀ , the number of rotations with the habit of the hammer pins as an axis is adjusted.

The apparent outer diameter D _{0 and the} habit pitch P ₀ given here are the habit pitch P ₁ and the apparent outer diameter d ₀ when the steel cord is twisted thereafter.
The apparent outer diameter D ₀ is a value considerably larger than the apparent outer diameter d ₀ when the steel cord is formed.

The wires constituting the steel cord include:
Usually, a steel wire having a carbon content of 0.70 to 0.95 wt% is used. However, in order to impart high strength and good toughness to the steel cord, each of the wires has a carbon content of 0.80 to 0.5%.
It is more preferable to use 90 wt% steel wire. Furthermore, in order to improve the adhesion between the rubber material and the steel cord, it is preferable to use a plated one such as brass plating or bronze plating for each of the above-mentioned strands.

Next, in order to confirm the performance characteristics of the steel cord of the present invention, in addition to the above embodiment, the wire diameter d _{1 of} the core strand, the pitch P _{1 of} the habit, and the apparent outer diameter d ₀ were respectively different. The steel cords of the other Examples and Comparative Examples were compared with conventional steel cords, and the breaking load, elongation, rigidity, rubber penetration rate, compression fatigue property, and workability were evaluated. I got the result like this. By the way, all the wires constituting each of the cords promoted in the test had a carbon content of 0.72% by weight, and the surfaces thereof were subjected to brass plating.

In the table, BL is the breaking load, EL is the elongation,
FL is rigid, RP is rubber penetration, RF is compression fatigue, H
W is handling workability, P ₁ is the habit pitch of a small spiral wire with a substantially spiral shape, d ₀ is the apparent outer diameter, d ₁ is the wire diameter of the core wire, and d ₂ is the wire diameter of the side wire. Show.

[0024]

[Table 1]

In the above evaluation, the elongation EL (%) indicates the elongation at break of the steel cord, and this value is desirably in the range of 3.0 to 4.0 for this kind of steel cord.

The rigidity FL is determined by embedding five steel cords in a rubber sheet having a thickness of 5 mm and vulcanizing under pressure.
A load was applied to the center while supporting both points at an interval of 1 cm, and the load required to deflect this sheet by 5 mm was measured.
And 100 as an index. Higher values are better,
Even if it is too large, the flexibility becomes poor, and 110 or less is preferable.

The infiltration rate RP (%) of the rubber material is such that a 100% modulus is 35 kg / cm ² of a rubber material (when used as a tire breaker for embedding a steel cord) under the condition that a tensile load of 5 kg is applied to each cord. Normal rubber material)
After embedding in steel, pressurized and vulcanized, take out the steel cord, disassemble the cord, observe a certain length between the strands, and compare the observed area with the area with a trace of rubber contact. Was calculated as a percentage and the average value was displayed. This value needs to be 80 or more.

The compression fatigue RF (%) is calculated by embedding a plurality of steel cords each in a rubber material having a 100% modulus of 35 kg / cm 2 to form a composite sheet. Using a tester, the number of repetitions until the cord was broken after fretting wear, buckling, etc. was determined, and the cord of Conventional Example 1 was expressed as an index with 100 as the index.

The handling workability HW is an evaluation of the complexity of the work during the production of the steel cord and the formation of the composite sheet and the handleability of the cord. X was evaluated as very poor compared with the code, Δ as slightly inferior, and ○ as no difference.

In Table 1, in Experiment No. Conventional example 1 of 1
Is a tight-twisted open-structure steel cord whose cross-sectional structure is shown in FIG. 3 (a). Rubber penetration is better than that of the closed-twisted steel cord, but it is still not enough, and the elongation is 2.8. %, Which is a low value. Experiment N
o. Conventional example 2 has a 1 × 12 bundle twist structure whose cross-sectional structure is shown in FIG. 3B, but 3 × 0.27 / 9 × 0. It is a steel cord with a 25 structure, with very poor rubber penetration and poor rigidity.

Experiment No. Comparative Example 1 of No. 7 has d ₁ / d
₂ = 1, P ₁ = 0.1 P, d ₀ = 1.03 d ₁ , the diameter of the core element wire and the side element wire is the same, and the substantially spiral habit of the core element wire is too small. There is almost no infiltration and compression fatigue, rigidity and elongation are all inferior. Experiment N
o. Comparative Example 2 of _No. 8 has P ₁ = 0.9P and d ₀ = 1.59d
₁ , which has a substantially large small spiral shape of the core element wire, so that it is inferior in rubber penetration, has poor compression fatigue and elongation, and has poor handling workability. Experiment No. Comparative Example 3 of 9
Inferior d ₀ = 1.50d ₁ a was in also similar rubber penetration as in Comparative Example 2 for the outer diameter of the apparent habit substantially smaller spiral is too large for Shinmotosen, compression fatigue resistance, elongation and handling properties . Experiment No. Comparative Example 4 of _No. 10 is d ₁ / d ₂
= 1.5, d ₀ = 1.04d ₁ , and the wire diameter ratio between the core element wire and the side element wire is too large, and the apparent outer diameter is too small. Poor workability, elongation and handling.

On the other hand, in experiment no. 3 to 6 of the present invention 1
Steel cords Nos. 4 to 4 satisfied rubber infiltration, compression fatigue, elongation, rigidity, and workability, and proved to be optimal as a rubber product reinforcing material.

[0033]

[Effect of the Invention] The steel cord for reinforcing a rubber product of the present invention has a hollow portion inside the cord over substantially the entire area in the longitudinal direction of the cord, and is a range in which the cord can be stretched under an extremely low load. Also, handling workability is good. In addition, when the steel cord is covered with rubber material, the rubber material surely spreads between the wires constituting the steel cord, forming a complete composite with rubber material, preventing corrosion of the cord and preventing the rubber material from being damaged. And the code separation phenomenon can be prevented. Therefore, buckling does not easily occur even when a repeated bending stress is applied, and the wear due to the fretting phenomenon is small, so that the fatigue property is excellent. Further, since the rigidity is improved, the amount of the steel cord embedded in the rubber material can be reduced, and the weight can be reduced, and the rolling resistance of the tire is improved.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an embodiment of a steel cord for reinforcing rubber products of the present invention.

FIGS. 2A and 2B are schematic cross-sectional views showing a conventional steel cord having a closed twist structure.

FIG. 3 shows an improved conventional steel cord;
(A) is a schematic sectional view showing a steel cord of Conventional Example 1,
(B) is a schematic sectional view showing a steel cord of Conventional Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel cord 2 Core wire having a small spiral in a substantially spiral shape 3 Side wire A Cavity C Crevice O, S Steel cord

Claims (1)

(57) [Scope of request for utility model registration] 1. At the center , an apparent outer diameter d ₀ = 1.08d
_{1 ~1.30d 1:} substantially spiral is (d ₁ Shinmotosen diameter)
Core wire having a small habit (core wire diameter d ₁ = 0.
20～0.40Mm) was placed one in steel cord of 1 + 6 structure formed by twisting a pitch P (P = 6~20mm) by disposing side wire six therearound, Shinmoto
The substantially spiral shape of the line has a pitch P ₁ = 0.2P ~
0.7P , and the wire diameter d _{1 of the} core wire and the wire diameter d _{2 of the} side wire
Rubber products reinforcing steel cord for the ratio of the is characterized in that it is a d ₁ / d ₂ = 1.1~1.4.