JPH06211009A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To secure an adhesive property between the coating brass plating of a wire and rubber to be bonded to the plated part, and improve the durability of a bead against input during the travel of a tire by adjusting the forming of the plated wire. CONSTITUTION:In a bead wire 3 formed of an annular core 1 and metal layers 21, 22 wound in coil shape around the core 1, the outer coil-shaped metal layer is formed of brass-plated carbon steel, and the core is formed of carbon steel with carbon content equal to or less than that of the layer. A forming ratio b/a is then set to be b/a>0.90, where (b) is the inner diameter of the circle of the coil-shaped metal layer at the time of taking this bead wire out of a new tire manufactured using this bead wire and loosening the wound metal layer, and (a) is the bead inner diameter at the time of being embedded in the tire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire provided with a cable beat wire for reinforcing a bead portion of a tire.

[0002]

2. Description of the Related Art Conventionally, a cable bead wire used to reinforce a bead portion of a tire is brass-plated to optimize the plating composition, thickness, and coating rubber so that the wet heat deterioration between the bead wire and the rubber can be prevented. Good and
There has been one that secures high adhesive strength and adhesive stability, prevents wild wires, etc., and improves durability (see JP-A-2-256503).
In addition, since the bead core is made of a material having a lower elastic modulus than that of the layer, the bead core is flexible enough to be deformed during a tire mounting operation, so that some of the bead cores have some durability. (Japanese Patent Laid-Open No. Sho 50
-52703 gazette).

[0003]

However, in the above-mentioned conventional example, the adhesiveness is improved by changing the plated surface to brass, but the patterning ratio of the layer has not been optimized. That is, when a high load is applied, the intermediate layer may be crushed at the current layer patterning rate (0.74 to 0.80), and the crushed wire may cause the carcass of the tire to roll along with the tire rolling. There was a case where it penetrated and was connected to the separation between plies. INDUSTRIAL APPLICABILITY The present invention secures the adhesiveness between the brass plating that covers the wire and the rubber that adheres to the plated portion, and adjusts the shaping of the brass-plated wire, that is, reduces the degree of tightening of the wire. The purpose of this is to improve the durability of the bead against input while the tire is running.

[0004]

In order to achieve the above object, in a pneumatic radial tire of the present invention, a layer formed of an annular inner core and a metal layer wound around the core in a coil shape. Structure is 1 + A + B + C
+ D + E (where A to E are the number of layers in each layer, A = 6 to 12, B = 0 or 12 to 20, C = 0 or 20 to 28, D = 0 or 26 to 34, E = 0) Or 30-38), the outer coil-shaped metal wire is made of brass-plated carbon steel, and the core is made of carbon steel having a carbon content equal to or lower than that of the coil-shaped metal layer. And
The bead wire is taken out from a new tire manufactured using the bead wire, the inner diameter of the circle of the metal layer when the wrapped metal layer is loosened is b, and the inner diameter of the bead when it is embedded in the tire is When a is set, b / a is set as a patterning rate, and b / a> 0.90 is provided. The bead plating composition in the above is the content ratio of copper and zinc Cu / Z
From the viewpoint of adhesiveness, n = 45/55 to 80/20 is preferable, and the carbon content of the outer coil-shaped metal layer is preferably 0.5 to 0.9% by weight.

[0005]

The operation and effect of the present invention configured as described above will be explained. A layered structure formed by the annular inner core of the present invention and a metal layer wound around the core in a coil shape is 1 + A + B + C + D + E (however, A to E are the number of layers in each layer, A = 6 to 12, B = 0 or 12 to 2
0, C = 0 or 20-28, D = 0 or 26-3
4, E = 0 or 30 to 38), the coiled metal wire outside the bead wire is made of brass-plated carbon steel, and the core has a carbon content equal to or lower than that of the coiled metal layer. If you take out the cable bead wire from a new tire manufactured using steel and untwist the twist of the outer layer from the product state, it will become a coiled ring, but its diameter is b, the inner core diameter Is defined as a, the mold ratio b / a> 0.90, while the carbon content of the inner core is made smaller than the carbon content of the metal layer so that the tightening between the metal layers is neither strong nor weak. It becomes a moderate degree, the restraining force between the wires becomes appropriate and fretting does not occur, and the tension sharing received by the wires during tire running is made uniform. DOO can result, eliminates also as intermediate layer a layer is crushed, it is possible to improve the durability of the bead. When the mold ratio b / a is less than 0.90, the metal layers are strongly clamped to increase the binding force between the wires, and as a result, the fretting phenomenon occurs during running. In that case, if the carbon content of the core is higher than the carbon content of the metal layer, the elongation rate of the layer will be smaller than the elongation rate of the core, so the tightening between layers will inevitably become strong and the durability of the bead will be reduced as a whole. It will be.

Further, regarding the bead plating composition at the time of actual manufacture, the content ratio of copper and zinc is Cu / Zn,
If the Zn content exceeds 55%, the adhesiveness between the wire and the rubber in the tire in a short time will be poor, while if the Zn content is less than 20%, the surface Cu content will be extremely high.
The wet heat deterioration property deteriorates, and in each case, separation occurs between the bead and ply due to poor adhesion. Further, if the carbon content of the outer coil-shaped metal layer is less than 0.50% by weight, it is difficult to withstand the stress applied to the bead during running, and conversely, if it is more than 0.90% by weight, at the time of molding. It is not suitable as a material for the bead because it is difficult to bend and the bead that can withstand the stress acting during tire running cannot have the minimum required elongation. Further, the value of the carbon content of the core is made smaller than the value of the carbon content of the layer in order to equalize the distribution of tension received by the wire during tire running. (Because the layer is twisted, it has high extensibility, and it is necessary to make it softer than the steel material of the layer in order to obtain extensibility equivalent to the layer in the core.)

[0007]

Embodiments will be described below with reference to the drawings. The bead wire in the embodiment of the present invention is shown in FIG.
As shown in FIG. 1, an annular inner core 1 having a bead as shown in (a) and the number of layers A = 6 to 12 around the core 1.
The first wire 2 ₁ is formed by sequentially winding the bead wires until the density becomes dense, and then the number of layers B = 0 or the second layer 2 _{2 of} 12 to 20 and the number of layers C = 0 or 20.
~ 28 third layer 2 ₃ , number of layers D = 0 or 26 ~ 3
4th layer 2 of ₄ and 5th of layer number 0 or 30 to 38
A bead wire 3 consisting of a metal layer 2 in which layers ₂₅ are formed in sequence is embedded in the bead portion of a new pneumatic radial tire. When the bead wire 3 is taken out from the pneumatic radial tire and the wound metal layer 2 is loosened, the metal layer 2 shown in FIG.
Has a coil shape as shown in FIG.

Then, assuming that the inner diameter b of the circle of the metal layer at that time is a, the inner diameter of the bead when it is buried in the tire is a, and b / a is a molding ratio, the relationship of b / a> 0.90 is satisfied. As described above, the cable bead wire 3 is formed. The outer coil-shaped metal layer 2 in this case is made of brass-plated carbon steel, and the core 1 is made of carbon steel having a carbon content equal to or lower than that of the outer coil-shaped metal layer 2. An example of the cross-sectional structure of the cable bead wire 3 according to the embodiment is as shown in FIG.

Here, the structures of the embodiments satisfying the above conditions are 1 × 3.0 + (7 + 12) × 2.2 and 1 ×.
3.0+ (8 + 14 + 20) × 1.8, the core is a cable bead wire made of carbon steel having a carbon content equal to or less than that of the metal layer, and the 50% modulus after heat vulcanization is 20 to 80 kg / cm ² . Each tire coated with a certain rubber was manufactured, an experiment was conducted by the following test method, and the test results are shown. I. Test method 1. Test conditions for radial tires (TBR) for truck buses After heating and vulcanizing a cable bead wire having a structure of 1 × 3.0 + (7 + 12) × 2.2 and a plating composition of preferably Cu / Zn = 60/40 Of a rubber-coated tire having a 50% modulus of 20 to 80 kg / cm ² , and filling the tire with an internal pressure of 9.00 kg / cm ² ,
The drum was continuously run under a test load of 5,500 kg, the metal layer of the cable bead wire was crushed, and the running distance until separation (Note) between the bead and the carcass ply occurred was evaluated (Table 1 reference). (Note) Checking the separation status is 1,000k
The holography test was performed by removing the tire from the drum every time the vehicle traveled m times.

2. Aircraft radial tires (A
PR) test conditions The cable bead having a structure of 1 × 3.0 + (8 + 14 + 20) × 1.8 and a plating composition of preferably Cu / Zn = 60/40 has a 50% modulus of 20 to 50 after heat vulcanization. A tire was manufactured by coating a rubber of 80 kg / cm ² and the tire was filled with an internal pressure of 230 psi and a test load of 2 ton at a speed of 40 mile / h for 10 minutes, then stopped for 50 minutes, and set as one cycle. When repeated, the number of times until the bead coating rubber separated was evaluated (see Table 2). In Tables 1 and 2, the bead wire is taken out from a new radial tire and the ratio b / a of the die diameter b of the outer metal layer to the inner diameter a of the core when the twist of the outer metal layer wound around is loosened Of the core and the carbon content of the outer metal layer were changed to produce a rubber composite of the coated rubber and the cable bead wire.
Radial tires for trucks and buses (TBR) and aircraft radial tires (AP) with bead portions reinforced with composites
R) was manufactured, run under the above-mentioned test conditions, and examples and comparative examples are shown below.

Here, it is known from experience that the diameter of the mold when taken out from the tire product is almost proportional to the diameter of the mold at the time of manufacture. You just have to adjust the angle and distance between the rollers. At that time, the outer metal layer is formed by twisting a linear wire at an angle with respect to the horizontal angle and passing the wire through a roller with a bead diameter suitable for the tire diameter before twisting and winding around the annular inner core. Molding rate 0.70, 0.85, 0.9 when removed from the product
In order to obtain 4, 1.06, the mold rate at the manufacturing stage is 0.50 to 0.60, 0.65 to 0.75, 0.80, respectively.
It is adjusted to a value between 0.90 and 0.85 to 0.95. Also, to obtain a metal layer with a mold rate of ∞,
You can use a machine to wind the wire from the reel directly around the core without shaping.

II. Test results

[Table 1]

[Continued from Table 1]

[Table 2]

[Continued from Table 2]

From the above test results, the radial tires for truck buses have the same 1 × 3.0 + (7 + 12) × 2.2 bead structure as can be seen from Examples 1 to 3 and Comparative Examples 1 to 4. It has been found that when the mold ratio (b / a) is 0.90 or less, separation occurs regardless of the weight% of the carbon content of the core and the metal layer.
In addition, as for radial tires for aircraft, Example 1 to
3, as can be seen from Comparative Examples 1 to 4, the die attachment rate (b / a)
Was 0.90 or less, it was confirmed that the number of rotations of the drum running until the separation of the bead coating rubber under the above conditions was extremely low, which was likely to occur.

[0014]

Since the present invention is constructed as described in detail above, the adhesiveness between the coated brass plating of the wire and the rubber portion to be bonded to the plated portion is sufficient as compared with the conventional one. The outer coil-shaped metal layer is made of brass-plated carbon steel, while the core is made of carbon steel whose carbon content is equal to or less than that of the outer coil-shaped metal layer. Is less likely to occur, the rubber layer is not crushed, and by adjusting the type of the brass-plated wire, it is possible to improve the durability of the bead against input during tire running. It is a thing.

[Brief description of drawings]

FIG. 1 is a perspective view of a bead wire having a coiled metal layer wrapped around an inner core.

FIG. 2 (a) is a view showing an annular inner core of a bead. (B) is the figure which showed the state which took out the bead wire from the new tire and loosened the metal layer wound around the core.

FIG. 3 is a cross-sectional view of a bead wire according to an embodiment of the present invention.

[Explanation of symbols]

 1 inner core 2 metal layer 3 bead wire

Claims (1)

[Claims] 1. A layered structure formed of an annular inner core and a metal layer wound in a coil around the core has a structure of 1 + A + B + C + D + E (where A to E are the number of layers in each layer, and A = 6-12, B = 0 or 12
-20, C = 0 or 20-28, D = 0 or 26-
34, E = 0 or 30-38), the outer coiled metal layer consists of brass-plated carbon steel and the core has a carbon content equal to or less than that of the coiled metal layer. It is composed of carbon steel, the bead wire is taken out from a new tire manufactured using the bead wire, and the inner diameter of the circle of the metal layer when the metal layer wound in a coil is loosened is b, A pneumatic radial tire provided with a cable bead wire, wherein b / a is a molding ratio and b / a> 0.90 where a bead inner diameter when embedded in the tire is a.