JP3337509B2 - Pneumatic radial tire - Google Patents

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, brass plating is applied to a cable bead wire used to reinforce a bead portion of a tire, and a plating composition, a thickness, and a covering rubber are optimized so that the wet heat deterioration between the bead wire and the rubber is reduced. Good things,
There has been one that ensures high adhesion and adhesion stability, prevents wild wires and the like, and improves durability (see JP-A-2-256503).
In addition, since the bead core is made of a material having an elastic coefficient lower than that of the layer, the bead core is flexible enough to be deformed during the mounting operation of the tire, and therefore, there are some which have a certain degree of durability. (Japanese
-52703).

[0003]

However, in the above-mentioned conventional example, the adhesion is improved by changing the plating surface to brass, but the mold ratio of the layer is not optimized. That is, when a high load is applied, the intermediate layer may be crushed at the current layer molding rate (0.74 to 0.80), and the crushed wire may cause the carcass of the tire to be rolled as the tire rolls. In some cases, it penetrated and led to separation between plies. The present invention ensures the adhesion between the brass plating covering the wire and the rubber that adheres to the plated portion, and adjusts the molding of the brass-plated wire, that is, reduces the degree of tightening of the wire. Accordingly, it is an object of the present invention to improve the durability of the bead with respect to an input during tire running.

[0004]

In order to achieve the above object, in a pneumatic radial tire according to 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), wherein the outer coiled metal wire is made of brass-plated carbon steel, and the core is made of carbon steel having a carbon content equal to or less than that of the coiled metal layer. And
Take out the bead wire from a new tire manufactured using the bead wire, b is the inside diameter of the circle of the metal layer when the wound metal layer is loosened, and b is the bead inside diameter when buried in the tire. When a is set, b / a is a mold ratio, and b / a> 0.90 is provided. In addition, the plating composition of the bead in the above was a Cu / Z content ratio of Cu / Z.
n = 45/55 to 80/20 is preferable from the viewpoint of adhesiveness, and the carbon content of the outer coiled metal layer is more preferably 0.5 to 0.9% by weight.

[0005]

The function and effect of the present invention constructed as described above will be described. The layer structure formed by the annular inner core of the present invention and the metal layer wound around the core in a coil shape 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 2
0, C = 0 or 20-28, D = 0 or 26-3
4, E = 0 or 30-38) 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 less than that of the coiled metal layer. When a cable bead wire is taken out from a new tire manufactured using a steel-made tire, and the twist of the outer layer is released from the product state, a coil-shaped ring is formed. When a is defined as a, the mold ratio b / a is greater than 0.90. On the other hand, when the carbon content of the inner core is smaller than the carbon content of the metal layer, the tightening between the metal layers is neither strong nor weak. It is moderate, the restraining force between the wires is appropriate, fretting does not occur, and the tension distribution applied to the wire while running the tire 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. If the mold ratio b / a is less than 0.90, the tightening between the metal layers is strong and the restraining force between the wires is increased, and as a result, a fretting phenomenon occurs during running. In that case, if the carbon content of the core is larger than the carbon content of the metal layer, the elongation of the layer is smaller than the elongation of the core, so the tightening between the layers will inevitably increase, and the durability of the bead will decrease as a whole Will be.

[0006] Further, regarding the plating composition of the bead at the time of actual production, the content ratio of copper and zinc is Cu / Zn,
When Zn exceeds 55%, the adhesiveness of the wire and rubber in the tire in a short time is inferior, while when Zn is less than 20%, the content of surface Cu becomes very large,
Deterioration in wet heat is reduced, and separation occurs between beads and plies due to poor adhesion. Further, when the carbon content of the outer coiled metal layer is less than 0.50% by weight, it is difficult to withstand the stress applied to the bead during running. It is not suitable as a bead material because it is difficult to bend and a required minimum elongation cannot be ensured for a bead that can withstand the stress applied during tire running. The reason why the value of the carbon content of the core is made smaller than the value of the carbon content of the layer is to make the tension distribution applied to the wire uniform during tire running. (Because the layer is twisted, it has high elongation, and it must be softer than the steel material of the layer to give the core the same elongation as the layer.)

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 2 shows a bead wire according to an embodiment of the present invention.
As shown in FIG. 1 (a), an annular inner core 1 of a bead and the number of layers A around the core 1 as shown in FIG.
The first layer 2 ₁ is formed bead wires are sequentially wound until tight, then the second layer of the layer number B = 0 or 12 to 20 2 _2, the number of layers C = 0 or 20
-28 _third layers 23, number of layers D = 0 or 26-3
4 of the fourth layer 2 ₄ and the fifth layer number 0 or 30-38
A bead wire 3 composed of a metal layer 2 on which layers ₂₅ are sequentially formed is embedded in a bead portion of a new pneumatic radial tire. The bead wire 3 is taken out of the pneumatic radial tire, and the wound metal layer 2 is loosened to obtain the metal layer 2 shown in FIG.
Has a coil shape as shown in FIG.

If the inner diameter b of the circle of the metal layer at that time and the inner diameter of the bead when buried in the tire are a, and b / a is the mold ratio, the relationship of b / a> 0.90 is satisfied. Thus, the cable bead wire 3 is formed. In this case, the outer coiled metal layer 2 is made of carbon steel plated with brass, and the core 1 is made of carbon steel having a carbon content equal to or less than that of the outer coiled metal layer 2. One example of the cross-sectional structure of the cable bead wire 3 according to the embodiment is as shown in FIG.

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

[0010] 2. Pneumatic radial tires for aircraft (A
PR) Test Conditions The 50% modulus after heating and vulcanizing a cable bead whose structure is 1 × 3.0 + (8 + 14 + 20) × 1.8 and whose plating composition is preferably Cu / Zn = 60/40 is 20 to A tire is manufactured by coating with a rubber of 80 kg / cm ² , and the tire is run at a speed of 40 mile / h for 10 minutes under the conditions of a filling internal pressure of 230 psi and a test load of 2 tons, then stopped for 50 minutes, and the cycle is defined as one cycle. When repeated, the number of times until the bead portion coating rubber separated was evaluated (see Table 2). In Tables 1 and 2, the bead wire was taken out of a new radial tire, and the ratio b / a of the mold diameter b of the outer metal layer to the core inner diameter a when the twist of the wound outer metal layer was loosened (molding). Rate) and the core was changed in the carbon content of the outer metal layer to produce a rubber composite of coated rubber and cable bead wire.
Radial tires for trucks and buses (TBR) and radial tires for aircraft (AP)
R) is manufactured and run under the above test conditions, and examples and comparative examples are as follows.

Here, it is known from experience that the die forming diameter when taken out of a tire product is substantially proportional to the die forming diameter at the time of manufacture. The angle and distance between the rollers may be adjusted. At that time, before the outer metal layer is twisted and wound around the annular inner core, a straight wire is formed at an angle with respect to the horizontal angle and the wire is passed through a roller with a bead diameter suitable for the tire diameter. Mold removal rate when removed from product 0.70, 0.85, 0.9
In order to obtain 4, 1.06, the mold ratios in the manufacturing stage are 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 ∞
The wire from the reel can be wound directly around the core without using a machine.

II. Test results

[Table 1]

[Continuation of Table 1]

[Table 2]

[Continuation of 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 was found that when the mold ratio (b / a) was 0.90 or less, separation occurred irrespective of the magnitude of the weight% of the carbon content of the core and the metal layer.
In addition, the radial tires for aircraft are also described in Examples 1 to 4.
3. As can be seen from Comparative Examples 1 to 4, the type ratio (b / a)
Is 0.90 or less, the running speed of the drum until the separation of the bead portion coating rubber under the above conditions occurs is extremely low, and it has been confirmed that this easily occurs.

[0014]

As described above in detail, since the present invention is constituted, the adhesiveness between the brass plating covered with the wire and the rubber part to be bonded to the plated part is more satisfactory than the conventional one. The outer coiled 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 coiled metal layer. Is less likely to occur, the rubber layer is not crushed, and furthermore, by adjusting the shape of the brass-plated wire, it is possible to improve the durability of the bead with respect to the input during running of the tire. Things.

[Brief description of the drawings]

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

FIG. 2 (a) is a diagram showing an annular inner core of a bead. (B) is a diagram showing a state in which a bead wire is taken out of a new tire and a metal layer wound around a core is loosened.

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

[Explanation of symbols]

 1 Internal core 2 Metal layer 3 Bead wire

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60C 15/04 D07B 1/06

Claims (1)

(57) [Claims] 1. A layer structure formed of an annular inner core and a metal layer wound in a coil shape around the core has a layer 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 is made of brass-plated carbon steel, and the core has a carbon content equal to or less than 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 shape is loosened is b, A pneumatic radial tire provided with a cable bead wire, wherein b / a is a mold ratio when a bead inner diameter when buried in the tire is a, and b / a> 0.90.