JP2000351306A - Pneumatic tire and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve production efficiency while securing durability of a bead part by providing a rubber layer formed by integrally extruding bead filler rubber, abrasion rubber and sidewall rubber on the outside of left/right bead cores and left/right folding-back parts. SOLUTION: When folding back both ends of a carcass 2 toward the outside from the inside on left/right bead cores 3, the folding-back part 2A is brought into close contact with carcass ply 2 by containing only the bead cores 3, and three-layer rubber 7 formed by integrally extrusively molding three members of bead filler rubber 4, abrasion rubber 5 and sidewall rubber 6 of a cross-sectional slender triangle or wedge shape is installed outside the folding-back part 2A. The bead filler rubber is not installed on the bead cores 3, and the rubber 4 is stuck to the folding-back part 2A as the three-layer rubber 7 together with the abrasion rubber 5 and the sidewall rubber 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire and a method of manufacturing the same, and more particularly, to a method in which a bead core is wound around an end of a radial carcass, and abrasion rubber, bead filler rubber and side The present invention relates to a radial pneumatic tire formed by extruding a three-layer rubber of wall rubber integrally, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a pneumatic tire, particularly a radial tire, a bead filler rubber is attached to an outer peripheral portion of a bead core, and both ends of the carcass are folded in such a manner as to enclose the bead filler rubber, and a folded portion is formed. Basically, rubber and sidewall rubber are individually adhered and vulcanized.

[0003]

In the conventional example in which a bead filler rubber is mounted on the outer periphery of a bead core, a mounting process is required in tire manufacturing, which is troublesome, and there is a possibility that mounting accuracy may be deviated. Also, when the bead core configuration is the same and the bead filler rubber is different,
It became another member (part), and there was trouble in parts management. In the pneumatic tire disclosed in Japanese Patent Application Laid-Open No. 52-131305, the folded portions at both ends of the carcass ply are folded so as to include only the bead core, and bead filler rubber (rubber stock) is provided outside the folded portion. ) Is mounted, and a pneumatic tire in which a bead core and a bead filler rubber are separated has been proposed.

However, in the pneumatic tire disclosed in this publication, since only the bead core is included in the folded portion, there is a possibility that a cavity is formed in the radially inner portion of the close contact portion between the folded portion and the carcass. Therefore, it is necessary to insert a small amount of rubber stock (having a triangular cross section in the official gazette) into the cavity, which increases the number of parts and makes the tire manufacturing process cumbersome. It took something. Therefore, in the present invention, in a pneumatic tire including only a bead core at a folded portion at both end portions of the carcass ply, outside the folded portion, abrasion rubber, bead filler rubber, and three-layer rubber of side wall rubber are integrally extruded. An object of the present invention is to improve the production efficiency by sticking the object while securing the durability of the bead portion.

[0005]

The pneumatic tire according to the present invention employs the following technical means to achieve the above-mentioned object. That is, the carcass ply is provided with a folded portion in which both ends are folded from the inside to the outside around the left and right bead cores, and the bead filler rubber, the abrasion rubber, and the sidewall rubber are integrally formed outside the left and right bead cores and the left and right folded portions. (Claim 1).

In the first aspect, each of the right and left bead cores has a number of wires arranged side by side in a cross section in the tire width direction, the number of wires being located on the radially outer peripheral side from the radially inner peripheral side. It is recommended that the number of the bead cores is reduced, and the contour shapes of the left and right bead cores are configured to be wedge-shaped or triangular (claim 2). With such a configuration, the folded portion is formed along the bead core without any step, so that the generation of a cavity can be suppressed and the durability of the bead portion can be improved. Further, in the method for manufacturing a pneumatic tire according to the present invention, when forming both ends of the carcass ply around the left and right bead cores from inside to outside on a forming drum to form a folded portion, the bead cores are formed on the left and right bead cores. -Folded without filler filler rubber, then
A rubber layer formed by integrally extruding bead filler rubber, abrasion rubber and sidewall rubber is attached to the outside of the left and right bead cores and the left and right folded portions, and then a breaker layer and tread rubber are attached to form a green tire. The green tire is vulcanized by a tire vulcanizer (claim 3).

According to this manufacturing method, alignment of the bead core and the bead filler rubber and alignment of the filler rubber, the abrasion rubber and the sidewall rubber are not required, and the productivity can be improved. Furthermore,
In the manufacturing method of the present invention, the left and right bead cores may be arranged such that the number of wires arranged side by side in the cross section in the tire width direction is larger in the radial outer periphery than in the portion located on the radial inner peripheral side. It is recommended that a bead core having a wedge-shaped or triangular contour be used with a reduced number of portions located on the side (claim 4).

According to the fourth aspect, it is possible to reduce the formation of a cavity in the outer peripheral portion of the bead core, and to provide a pneumatic tire in which the durability of the bead portion is ensured.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 (1) (2) and 2
(1) and (2) illustrate the manufacturing process of the pneumatic tire (radial tire) according to the present invention. In FIGS. 1 and 2, a carcass ply, preferably a radial carcass ply 2 is mounted on a forming drum 1 having a former 1A and a bladder portion 1B. The carcass ply 2 includes a warp made of organic fibers such as polyester and nylon,
A cloth obtained by rubberizing a blind woven fabric formed by weaving a warp made of cotton, cellulose fiber (polynosic) or the like can be used, but other known carcass plies can be used.

[0010] Both ends of the carcass ply 2 are mounted on the drum 1 with a turning margin, and an annular (ring-shaped) bead core 3 is mounted on the turning margin by means of a bead setter or the like. As shown in the drawing, both ends of the carcass ply 2 (only one is shown in the figure, but the other has the same configuration) are folded back from the inside to the outside so as to include the bead core 3 so that the folded portion 2A is formed. Have been. Next, as shown in FIG. 1 (3), a rubber layer 7 obtained by integrally extruding three members (three layers) of a bead filler rubber 4, an abrasion rubber 5 and a sidewall rubber 6 is formed.
Is attached to the outside of the folded portion 2A and the outside of the carcass ply 2, so that the folded portion 2A is in close contact with the carcass ply 2.

After the left and right bead cores 3 are connected by the carcass ply 2 and the rubber layer 7 is attached,
As shown in FIG. 2 (1), it is inflated, and a breaker layer (belt layer) 8 and a tread rubber 9 are adhered to the crown portion thereof.
As shown in FIG. 2 (2), the side edge of the tread rubber 9 is adhered to the sidewall rubber 6, and a green tire (raw tire) 10 having a toroidal cross section is formed here.
Thereafter, the green tire is mounted on a tire vulcanizer and vulcanized to produce a radial tire.

FIGS. 3 (1) (2) and 5 (1) (2)
3 shows an example of a bead portion of a vulcanized radial tire T. FIG. 3A shows a bead core 3 formed by bundling a large number of bead wires 3A as shown in FIG. 3 (2).
As shown in FIG. 4 (2), the bead core 3 formed by bundling a large number of bead wires 3A has a triangular or wedge-shaped cross section, that is, the number of wires 3A arranged side by side in the cross section in the tire width direction has a radius of The number of pieces located on the outer peripheral side in the radial direction is smaller than the part located on the inner peripheral side in the direction, and the contour is configured to be wedge-shaped or triangular. Further, FIG. The shape is a flat hexagon, and FIG. 5 (2) is a regular hexagon.

In both of the embodiments shown in FIGS. 3 and 5, when both ends of the carcass 2 are folded from the inside to the outside by the left and right bead cores 3, only the bead core 3 is included and the folded portion 2A is included. Is a three-layer rubber formed by integrally extruding a triangular or wedge-shaped bead filler rubber 4, an abrasion rubber 5 and a side wall rubber 6 integrally with the carcass ply 2 outside the folded portion 2A. 7 is mounted. In any of the embodiments, the bead core 3 does not have the bead filler rubber 4 attached thereto, and the rubber 4 is adhered to the folded portion 2A as a three-layer rubber 7 together with the abrasion rubber 5 and the sidewall rubber 6. .

In particular, as shown in FIGS. 3 (2) and 4 (2), the bead core 3 having a triangular or wedge-shaped contour.
Is adopted, the folded portion 2A and the carcass ply 2
There is little space formed between them, and the configuration is rich in durability. Since the abrasion rubber 5 is a contact portion with the rim, a rubber material having high abrasion resistance is used, and the bead filler rubber 4 is used as the folded portion 2A.
A rubber material having a hardness for suppressing the separation and the like is used. Also, in order to prevent separation from the edge 2B of the folded portion 2A, FIGS.
It is desirable to configure so as to cover the edge 2B as shown by.

[0015]

As described above in detail, according to the method of the present invention, the production efficiency can be greatly improved, and the durability of the bead portion of the pneumatic tire produced thereby can be improved.

[Brief description of the drawings]

FIG. 1 shows a manufacturing process of a pneumatic tire, wherein (1) is a first step, (2) is a second step, and (3) is a sectional view of a main part of a third step.

FIG. 2 is a cross-sectional view of a pneumatic tire manufacturing process, in which (1) is a fourth step and (2) is a fifth step.

FIG. 3 shows a bead portion of a tire produced by the method of the present invention, wherein (1) is a first example and (2) is a second example.

4 (1) shows the bead core of FIG. 3 (1), and FIG. 4 (2) shows the bead core of FIG. 3 (2).

FIG. 5 shows a bead portion of a tire produced by the method of the present invention, wherein (1) is a third example and (2) is a fourth example.

[Explanation of symbols]

 2 Carcass ply 2A Turn-up part 3 Bead core 4 Bead filler rubber 5 Ablation rubber 6 Sidewall rubber 7 Three-layer rubber

Claims (4)

[Claims] 1. A carcass ply comprising a folded portion formed by folding both ends of a carcass ply from inside to outside around left and right bead cores, and outside the left and right bead cores and the left and right folded portions,
A pneumatic tire comprising a rubber layer formed by extruding bead filler rubber, abrasion rubber and sidewall rubber integrally. 2. The left and right bead cores each have a smaller number of wires arranged side by side in the cross section in the tire width direction than a portion located on the radially inner peripheral side compared to a radially inner peripheral side. The pneumatic tire according to claim 1, wherein the contour shapes of the left and right bead cores are wedge-shaped or triangular. 3. When turning both ends of the carcass ply around the left and right bead cores from inside to outside on a forming drum to form a folded portion, beads are formed on the left and right bead cores.
The rubber layer is formed by extruding bead filler rubber, abrasion rubber, and sidewall rubber integrally on the outside of the left and right bead cores and the left and right folds, and then the breaker layer and the tread rubber are adhered. A method for manufacturing a pneumatic tire, comprising: forming a green tire by attaching the green tire; and vulcanizing the green tire with a tire vulcanizer. 4. Each of the right and left bead cores has a smaller number of wires arranged side by side in a cross section in the tire width direction than a portion located on a radially outer peripheral side than a radially inner peripheral side. The pneumatic tire manufacturing method according to claim 3, wherein a bead core having a wedge-shaped or triangular contour is used.