JPH08113016A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE: To prevent the occurrence of a bear at molding-vulcanizing time, thin a sidewall part, and reduce the weight by setting the bear preventive recess arranged on a sidewall outside surface in specific width, depth and area, and positioning this outside edge on the radial directional inside close to the tip of a bead apex. CONSTITUTION: A recessed part G extending in the tire circumferential direction by recessing sidewall rubber 9 is formed on a sidewall outside surface 9A. In this recessed part G, a recessed part width W between the outside edge Ga in the outside diameter direction and the inside edge Gb is set in 2 to 10mm, and a depth Gc up to a bottom surface GU from the sidewall outside surface 9A is set in 0.5 to 1.5mm, and this cross-sectional area K is set in 0.7 to 1.2mm<2> . The outside edge Ga is positioned on the radial directional inside close to the tip P of a bead apex 8, and a difference A in a radial directional height is set in 0 to 7mm. Therefore, a bear generated on the sidewall outside surface 9A at vulcanizing-molding time is restrained without increasing the weight of a tire, and improving the appearance of workmanship can be improved.

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 capable of eliminating a bare outer surface of a sidewall portion which tends to occur during vulcanization and molding without increasing the tire weight and improving the finished appearance.

[0002]

2. Description of the Related Art In order to form a pneumatic tire having a high tread rigidity such as a pneumatic radial tire, it is usually necessary to prepare a pneumatic tire as shown in FIG.
As shown in FIG. 1, a tread member a such as a belt layer and a tread rubber
Is molded separately from the tire frame member b such as a carcass, sidewall rubber, bead core, etc., and at the time of vulcanization, the tire frame member b is bulged to form a tread member a.
The so-called two-stage molding process of joining to is adopted.

In such a two-stage process, FIG.
As shown in FIG. 5, when the raw cover c forming the tire frame member b is put into the mold d and vulcanized and molded, the raw cover c may contact the mold d simultaneously and uniformly as shown in FIG. Without
There are a portion that comes into contact with the entire die d early and a portion that comes into contact with the die d afterwards.

Particularly, in the vicinity x of the bead apex tip, the raw cover c comes into contact with the mold with the latest delay, so that the flow of the sidewall rubber is apt to be defective, and a bare tire is produced on the finished tire, resulting in a poor finished appearance. There's a problem. In order to prevent the occurrence of such bears, conventionally,
We have dealt with this by increasing the rubber thickness in the x part near the tip of the bead apex.

[0005]

However, by increasing the rubber thickness as described above, the tire weight increases, and as a result, the rolling resistance increases. On the other hand, in the automobile industry, in order to improve fuel efficiency, demands for reduction of rolling resistance have become strict, and further reduction of tire weight has become necessary.

As a result of repeated studies to satisfy the above-mentioned demands, the inventor has found that by forming a recess at the tip of the bead apex where the sidewall rubber has been formed to have an unnecessarily thick wall rubber to prevent the occurrence of bareness. The present inventors have completed the present invention by discovering that the contact with the mold is good during the vulcanization molding and the rubber thickness can be reduced.

The present invention is based on the provision of a recessed portion on the outer surface of the side wall portion and at a regulated position and size, and by preventing the generation of bare during molding and vulcanization,
It is an object of the present invention to provide a pneumatic tire in which the sidewall portion can be formed thin and the weight of the tire can be reduced.

[0008]

DISCLOSURE OF THE INVENTION The present invention is directed to a carcass of a radial arrangement, in which a body part extending from a tread part to a bead core of a bead part through a side wall part is integrally provided with a turn-back part that turns around the bead core, and a bead core. The outer side of the tire in the radial direction and a bead apex made of a hard rubber that extends between the carcass main body portion and the folded portion to the sidewall portion, a sidewall rubber that forms an outer surface of the sidewall portion, and a bead portion of the bead portion. The outer surface,
Consists of a clincher rubber that overlaps the inside of the sidewall rubber and is harder than the sidewall rubber by extending outward in the radial direction, and for preventing a bear that extends in the tire circumferential direction by denting the sidewall rubber on the outer surface of the sidewall. The recess G is provided, and the recess G has a recess width W between the outer edge Ga and the inner edge Gb in the radial direction of 2 mm or more and 10 mm or less, and a depth Gc of 0.5 mm or more from the contour line of the outer surface of the sidewall portion. And the cross-sectional area K in the tire meridional section is 0.7 mm ² or more and 12 mm ² or less, and the outer edge Ga is located radially inward of the tip P of the bead apex and in the radial direction thereof. The height difference A is O or more and 7 mm or less, which is a pneumatic radial tire.

In the bead apex, the height H from the bead base line of the tip P of the bead apex is calculated as the tire cross-section height Ho.
It is preferably 0.23 to 0.48 times.

Incidentally, the recess G may be a groove which is endlessly wound in the circumferential direction, or may be a continuous body of recesses which are arranged intermittently in the circumferential direction.

[0011]

The height A in the radial direction between the outer edge Ga of the recess G and the tip P of the bead apex is set to 0 or more and 7 mm or less. The bead apex and clincher rubber are made of hard rubber as described above, and the sidewall rubber adjacent to these members is affected by the rigidity of the member made of hard rubber during vulcanization and molding, and the mold However, by providing the concave portion G, the rigidity of the sidewall rubber at the portion is softened, and as shown in FIG. 3, the outer surface of the sidewall portion of the green cover has a substantially uniform contour. By following the surface, vulcanization,
Even at the time of molding, the flow of the sidewall rubber is slight, and the occurrence of bare can be prevented.

When the height difference A in the radial direction becomes smaller than 0, that is, becomes a negative value, the sidewall rubber is influenced by the adjacent clincher rubber, so that the rubber flow is likely to be defective at another position. , There is a risk of bears. On the other hand, if it exceeds 7 mm, a recess is formed off the position where the bare is most likely to occur, and the effect of suppressing the bare is small.

Further, the width W of the recess is set to 2 mm or more and 10 mm or less. If the recess width W is less than 2 mm, the opposing wall surfaces of the recess G will abut against each other when the raw cover is expanded, and the outer surface of the sidewall part will be unevenly bonded to the mold. If the recess width W exceeds 10 mm and becomes large, the recess G extends to the vicinity of the bead portion, and the strength of the bead portion is reduced.

Further, the depth Gc of the recess G is 0.5 mm or more and 1.5 mm or less. If the depth Gc exceeds 0.5 mm and becomes large, the strength of the sidewall portion is deteriorated, and there is a risk that the tire will bend.

Further, the sectional area K of the recess G in the meridian section of the tire
Is 0.7 mm ² or more and 1.5 mm ² or less. If the cross-sectional area K is less than 0.7 mm ² , the effect of forming the recess is not obtained, and if it exceeds 0.15 mm ² , the strength of the sidewall portion is reduced.

As described above, according to the present invention, by organically combining and integrating the above-mentioned components, it is possible to prevent generation of a bare during vulcanization and molding and to reduce the weight.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the figure, a pneumatic tire 1 has a tread portion 2
And a pair of sidewall portions 3, 3 extending inward in the tire radial direction from both ends thereof, and a bead portion 4 extending inward of the sidewall portion 3.

Further, in the pneumatic tire 1, the bead core 5 of the bead portion 4 extends from the tread portion 2 to the sidewall portion 3.
A carcass 6 integrally provided with a folded-back portion 6b which folds around the bead core 3 from the inner side in the tire axial direction to the outer side in the main body portion 6a extending to And a belt layer 7 disposed on the.

Further, the pneumatic tire 1 has a body portion 6a of the carcass 6 on the outer side in the radial direction of the bead core 5.
And the bead apex 8 extending to the sidewall portion 3 between the side wall portion 3 and the folded portion 6b.
There is provided a sidewall rubber 9 forming an outer surface 9A which is an axially outward surface of the tire, and a clincher rubber 10 continuous with the sidewall rubber 9 by extending the outer surface of the bead portion 4 outward in the radial direction.

The bead apex 8 is made of rubber having a JISA hardness of 70 to 95 degrees and is harder than the side wall rubber 9, and a bead baseline L at the tip P thereof.
The height H from the tire cross-section height Ho is 0.23 to 0.4
The range is 8 times.

In this example, the carcass 6 is made of one carcass ply, and the carcass ply has a carcass cord made of an organic fiber such as nylon, polyester, rayon, or aromatic polyamide at 70 with respect to the tire equator C.
It is formed as a radial or semi-radial array juxtaposed at an angle of ~ 90 °. In this example, the height of the tip of the folded-back portion 6b from the bead base line L is slightly larger than the height H of the tip P of the bead apex 8 to form a high turn-up.

The belt layer 7 is composed of two belt plies 7A and 7B in this example.
In B, belt cords made of steel, such as nylon, polyester, rayon, aromatic polyamide, or organic fibers, or steel, are arranged between the belt plies 7A and 7B in directions intersecting with each other.

The clincher rubber 10 is made of a rubber having a JISA hardness of 65 to 80 degrees and is harder than the sidewall rubber 9, and extends inside the sidewall rubber 9 and obliquely with respect to the tire radius line. It is connected by the contact surface 10A.

On the outer surface 9A of the sidewall, there is formed a recess G formed by recessing the sidewall rubber 9 and extending in the tire circumferential direction. In this embodiment,
The concave portion G is formed as a single circular groove that circulates with the height from the bead base line L being substantially constant.

In this recess G, the side wall surface Gw and the bottom surface Gu of the recess are connected by a smooth curved surface, and the recess width W between the outer edge Ga and the inner edge Gb is 2 mm or more and 10 mm or less, or The depth Gc from the sidewall outer surface 9A to the bottom surface GU is 0.5 mm or more and 1.5 mm or less. Further, the cross-sectional area K of the groove G is 0.7 mm ²
Above and above 12 mm ² .

The outer edge Ga is located inward of the tip P of the bead apex 8 in the radial direction, and the height difference A in the radial direction is 0 or more and 7 mm or less.

The minimum rubber thickness M of the sidewall rubber 9 from the sidewall surface Gw or the bottom surface Gu of the recess G to the contact surface 10A of the clincher rubber 10 is preferably at least 1.0 mm or more. . This is because if the rubber thickness M is less than 1.0 mm, the strength of the sidewall rubber 9 is reduced and the sidewall portion 3 may be damaged.

As shown in FIG. 3, the recess G is provided with a projection 22 along the contour of the recess G on the molding surface 21 of the mold 20 during vulcanization molding, and the raw cover 11 is formed on the molding surface 21.
It is formed by pressing against.

During pressing, the protrusions 22 are formed on the raw cover 1.
Since 1 is provided at the position which comes into contact with the die 20 most lately,
The sidewall rubber 9 forming the outer surface 9A flows only slightly, and the occurrence of bare can be suppressed.

The height U of the inner edge Gb of the recess G from the bead bolus in L is preferably 25 mm or more.
Even if the height U is less than 25 mm due to the relatively small height of the bead apex 8, the concave portion G existing at this position is more likely to be formed earlier than other portions of the outer surface 9A of the sidewall portion 3. This is because it comes into contact with the mold 20, and no remarkable effect may occur.

[0031]

[Specific Example] Tires having tire sizes of 215/60 R16 (passenger car tires) and 10R15 6PR TG3 (light truck tires) and sidewalls during vulcanization and molding for tires (Examples 1 and 2) shown in FIG. 1 We investigated the occurrence of bears on the outer surface of the department. For comparison, a tire having a conventional configuration having no recess (conventional example 1,
Regarding 2), we also investigated and compared. The test results are shown in Table 1.

[0032]

[Table 1]

As a result of the test, it was confirmed that the occurrence of bears in the example was significantly reduced as compared with the comparative example.

[0034]

As described above, the pneumatic tire of the present invention is
Since the recess is formed by recessing the side wall rubber on the outer surface of the sidewall, and the position and size of the recess are regulated, the bear generated on the outer surface of the sidewall during vulcanization and molding does not increase the tire weight. It can be suppressed and the finished appearance of the tire can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an enlarged main part thereof.

FIG. 3 is a diagram showing a state at the time of joining the raw cover and the mold.

FIG. 4 is a cross-sectional view schematically showing a vulcanization and molding process.

FIG. 5 is a diagram illustrating a conventional technique.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 6a main body part 6b folded part 8 bead apex 9 sidewall rubber 9A outer surface 10 clincher rubber 10A contact surface A height difference G recessed portion Ga outer edge Gb inner edge Gc depth H bead Height of apex K Cross-sectional area of recess P Bead tip of apex W Width of recess

Claims (2)

[Claims] Claims: 1. A carcass of a radial arrangement in which a folded portion that folds back around a bead core is integrally provided in a main body portion from a tread portion to a bead core of a bead portion, and a carcass radially outside the bead core and the carcass. A bead apex made of hard rubber extending between the main body part and the folded part to the side wall part, a side wall rubber forming an outer surface of the side wall part, and an outer surface of the bead part, which is radially outward. And a clincher rubber that is harder than the sidewall rubber and overlaps the inside of the sidewall rubber by extending to the outside, and the sidewall G has a concave portion G for preventing the bear that extends in the tire circumferential direction by denting the sidewall rubber. At the same time, the recess G has an outer edge Ga and an inner edge Gb in the radial direction.
And the recess width W between 2 mm and 10 mm, the depth Gc from the contour of the outer surface of the sidewall is 0.5 mm and 1.5 mm, and the cross-sectional area K in the tire meridian section is 0.7.
mm ² or more and with a 12 mm ² or less, the outer edge G
a is located inward of the tip P of the bead apex in the radial direction, and the difference A in height in the radial direction is O or more and 7 mm.
A pneumatic radial tire characterized by the following. 2. In the bead apex, the height H of the tip P from the bead base line is the tire cross-section height Ho.
The radial radial tire according to claim 1, wherein the pneumatic radial tire is 0.23 to 0.48 times.