JPH04183616A - Radial tire for heavy load use - Google Patents

Abstract

PURPOSE:To enhance the durability of a bead part by arranging a metallic cord-reinforcing layer on the outside of a carcass ply, and arranging at least two layers of fiber cord reinforcing layers of a reed-screen structure on the outside of the metallic cord-reinforcing layer, and also by arranging respective fiber cords substantially in parallel. CONSTITUTION:In a tire, both end parts of a carcass ply 10 are folded back and wound up around bead rings 20 from the inside of the tire to the outside thereof, and are terminated at bead parts T. In this case, in the bead part T, a metallic cord-reinforcing layer 30 is arranged on the outside of the carcass ply 10 so as to extend from the inside of the tire to the outside thereof. Further, on the outside of the metallic cord-reinforcing layer 30, at least two layers of fiber cord reinforcing layers 40, 50 of a reed-screen structure are arranged so as to cover at least the terminal 10a of the winding-up part of the carcass ply 10 and the external terminal 30a of the metallic cord-reinforcing layer 30. Furthermore, in the fiber cord reinforcing layers 40, 50 of a reed-screen structure which have been arranged so as to be adjacent to each other, respective fiber cords between layers are arranged substantially in parallel to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heavy-duty radial tire with improved bead durability.

[Conventional technology]

Generally, in the bead part of heavy-duty radial tires, the fourth
As shown in the figure, the end of at least one carcass ply 1 made of metal cord is folded back and rolled up around the bead ring 2 from the inside of the tire to the outside, and terminates at a relatively low position. A metal cord reinforcing layer 3 and two fiber cord reinforcing layers 4 are provided on the outside of the ply 1.
, 5 are arranged.

These fiber cord reinforcing layers 4.5 are provided on the outside of the metal cord reinforcing layer 3 at the ends 1a of the rolled up portions of the carcass ply 1.
and the outer terminals 3a of the metal cord reinforcing layer 3 to prevent separation failure between the cord and its surrounding rubber, that is, the cord covering rubber, which is easy to live near these terminals 1a and 3a.

However, the above-mentioned separation failure still remains a problem in heavy-duty radial tires, and various proposals have been made to improve it. For example, Japanese Patent Publication No. 5B-3844 describes that the fiber reinforcing layer is a combination of an inner layer of a plain weave structure reinforcing layer of fiber cords and an outer layer of a blind structure reinforcing layer of fiber cords. Furthermore, Japanese Patent Publication No. 49-44122 and Japanese Patent Publication No. 57-8725 discloses that at least two fiber cord reinforcing layers, for example, a blind structure reinforcing layer, are arranged so that the fiber cords intersect diagonally with each other between the layers. In either case, it is possible to achieve a certain degree of separation prevention effect.

However, in the method described in Japanese Patent Publication No. 58-3844, since the plain weave structure reinforcement layer used as the fiber reinforcement layer is woven from warp and weft yarns, the areas where the cords of the plain weave structure cross are Since shear strain occurs, there is a problem in that separation occurs between the plain woven fabric forming the reinforcing layer and the rubber.

Furthermore, in the method described in Japanese Patent Publication No. 49-44122 and Japanese Patent Publication No. 57-8725, two or more fiber cord reinforcing layers are arranged so that the cords intersect obliquely between the layers. Similar to the above, there was a problem in that shear strain occurred at the portion where the cords crossed, and separation was likely to occur between the fabric and rubber forming the reinforcing layer.

[Problem to be solved by the invention]

The present invention has been made to solve the above-mentioned problems with the conventional heavy-duty radial tires, and although the bead portion has a fiber cord reinforcing layer, the fiber cord reinforcing layer does not contain fiber cords. The objective is to provide a heavy-duty radial tire that does not cause separation between the rubber and the rubber and has a durable bead part.

[Means to solve the problem]

That is, in the heavy-duty radial tire of the present invention, the end of the carcass ply is folded back and rolled up from the inside of the tire to the outside around the annular bead ring at the bead portion, and a metal cord reinforcing layer is applied to the outside of the carcass ply from the inside of the tire. At least two fiber cord blind structure reinforcing layers are arranged on the outside of the metal cord reinforcing layer so as to cover at least the ends of the rolled up portion of the carcass ply and the outer ends of the metal cord reinforcing layer. This is characterized in that the fiber cords of the mutually adjacent blind structure reinforcing layers are substantially parallel to each other between the layers.

As described above, in the present invention, since the fiber cords of the mutually adjacent blind structure reinforcing layers are made to be substantially parallel to each other between the layers, no distortion occurs between the layers, so that separation does not occur. Therefore, it is possible to improve the durability of the bead portion.

Hereinafter, the heavy load radial tire of the present invention will be explained in detail according to the drawings.

FIG. 1 is an explanatory cross-sectional view showing one example of the radial tire for heavy loads according to the present invention, FIG. 2 is an explanatory cross-sectional view showing another example of the radial tire for heavy loads according to the present invention, and FIG.
It is a partially cutaway plan view explanatory view showing the cord arrangement state of the fiber cord blind structure reinforcing layer in the figure.

In FIG. 1, the heavy load radial tire of the present invention is
The carcass ply 10 has a bead structure in which both ends of the carcass ply 10 are folded back and rolled up from the inside to the outside of the tire around an annular bead ring 20 and terminated at a bead part T.

The bead portion T includes a metal cord reinforcing layer 30 disposed outside the carcass ply 10 from the inside to the outside of the tire, and an end 10a of the rolled up portion of the carcass ply 10 and a metal cord reinforcing layer 30 on the outside of the metal cord reinforcing layer 30. It includes at least two fiber cord interdigital structure reinforcing layers 40 and 50 arranged so as to at least cover the outer ends 30a of the cord reinforcing layer 30.

The blind structure reinforcing layers 40 and 50 may be placed only on the outside of the metal cord reinforcing layer 30 on the winding side of the carcass ply 10 as shown in FIG. 1, or on the inside as shown in FIG. The blind structure reinforcing layer 40 can also be arranged to cover the entire metal cord reinforcing layer 30. Note that 60 in the figure indicates a rim flange for assembling the tire to the rim.

Here, each fiber cord of the blind structure reinforcing layer 40.50 is made of organic fiber such as nylon or polyester, and is, for example, a nylon cord with two strands of 1260 denier twisted and a cord density of 40 cords and 150 cords.

In addition, the carcass ply 10 and the metal cord reinforcing layer 30
The elastic modulus of the coating rubber is 50 to 150 kg/Cl.
It is preferable to use Rubber No. 11 having an elastic modulus of 40 to 130 kg/ciO as the coating rubber for the blind structure reinforcing layer 40.50.

In the present invention, mutually adjacent blind structure reinforcing layers 4
Regarding 0.50, it is an important requirement to arrange the respective fiber cords between the layers so that they are substantially parallel to each other, and by arranging them in this way, the separation between the cords and the rubber in the blind structure reinforcing layer is eliminated. , the durability of the bead portion can be dramatically improved.

That is, by arranging the fiber cords between the two blind structure reinforcing layers 40 and 50 substantially in parallel, the shear strain between these fiber cords is reduced, and the separation from the covering rubber is effectively eliminated. be.

Here, the fiber cords of the mutually adjacent blind structure reinforcing layers are substantially parallel to each other, as shown in FIG. Regarding the difference between the inclination angle θ2 of the fiber cord 51 of the blind structure reinforcing layer 50 in the radial direction, when 1θ, -θ21=θ゛, θ ・θ > Q @, and 06≦θ"≦20', preferably This means that O°≦θ゛≦10°.The angular difference between the two fiber cords 41, 51 is allowed up to 20°.

However, if the angle difference exceeds 20'', separation between the fiber cord and the rubber in the blind structure reinforcing layer tends to occur.

Note that the inclination direction of each of the fiber cords 41 and 51 is as follows:
It is the same with respect to the perpendicular to the circumference t connecting the ends lOa of the rolled up portion of the carcass ply 10.

Next, the structure and effects of the heavy-duty radial tire of the present invention will be further explained with reference to Examples.

〔Example〕

A radial tire with a tire size of 1000R2014PR was given the bead structure shown in Figure 1 above,
The durability of the bead portion of this tire was evaluated.

That is, the cord of the carcass ply 10 is made of steel (3+9+15(0,175) +IW), and the cord of the metal cord reinforcing layer 30 is made of steel (7×3(0,175)
, 15)) by using nylon (1260D/2) as each cord of the blind structure reinforcing layer 40.50, and arranging the fiber cords 41.51 so that the inclination angle difference is substantially parallel to 0°. A tire according to the invention was obtained.

On the other hand, for comparison, a conventional tire was obtained in the same manner as above, except that the angle difference between the fiber cords 4L 51 in the two-layer blind structure reinforcing layer was set to 60'.

For these two types of radial tires, the rims used are:
20 x 7.50V, tire internal pressure: 9.00kg/
c+a, load: 520Qkg, diameter 1707
45 km/h on a steel drum with a smooth surface of mm
The time required for separation to occur in the 40.50 part of the blind structure reinforcing layer at the bead portion was measured when running at a speed of /h.

As a result, the tire of the present invention did not cause separation even after 600 hours of running and had very good durability, whereas the conventional tire did not cause separation after 450 hours of running and had poor durability. Ta.

As is clear from these results, the heavy-duty radial tire of the present invention has extremely high durability at the bead portion.

〔Effect of the invention〕

As explained in detail above, in the heavy-duty radial tire of the present invention, since the fiber cords of the mutually adjacent blind structure reinforcing layers are arranged substantially parallel to each other, the shear strain between the layers is reduced, and the covering rubber The separation between the code and the code is effectively eliminated.

Therefore, the heavy-duty radial tire of the present invention has excellent bead portion durability and is particularly suitable as a high-speed tire.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing one example of the radial tire for heavy loads according to the present invention, FIG. 2 is an explanatory cross-sectional view showing another example of the radial tire for heavy loads according to the present invention, and FIG.
FIG. 4 is a partially cutaway plan view explanatory view showing the cord arrangement state of the fiber cord interlocking structure reinforcing layer in the figure, and FIG. 4 is a cross-sectional explanatory view showing an example of a conventional heavy-duty radial tire. 10...Carcass ply, 20...Bead ring,
30... Metal cord reinforcing layer, 40... Blind structure reinforcing layer, 41... Fiber cord, 50... Blind structure reinforcing layer, 51... Fiber cord, 60... Rim flange. Agent Patent Attorney Nobuo Ogawa −

Claims (1)

[Claims] At the bead part, the end of the carcass ply is folded back and rolled up around the annular bead ring from the inside of the tire to the outside, and a metal cord reinforcing layer is placed on the outside of this carcass ply from the inside of the tire to the outside of the tire. At least two fiber cord blind structure reinforcing layers are arranged on the outside so as to cover at least the ends of the rolled-up portion of the carcass ply and the outer ends of the metal cord reinforcing layer, and mutually adjacent blind structure reinforcement layers are arranged. A heavy-duty radial tire in which the fiber cords of each layer are substantially parallel to each other between layers.