JP2001039127A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease influence of spue generated at the time of vulcanization- forming and improve various performances of a tire in positions corresponding to the recessed parts in a tire having recessed parts for measuring the abrasion degree of the tire in plural portions by disposing metal mold air vent holes at the time of vulcanization-forming a tire in positions corresponding to the recessed parts. SOLUTION: Plural recessed parts 2 for measuring the abrasion degree of a tire are disposed along the cross direction of a tread 1. In this case, metal mold air vent holes at the time of vulcanization-forming the tire are disposed in positions corresponding to the recessed parts 2. Spue 3 inevitably generated at the time of vulcanization-forming the tire is formed at the bottom of the recessed part 2 corresponding to the air vent hole of the metal mold. Thus, it is not necessary to remove spue remaining on the surface of the tire after vulcanization forming. The thickness of tread rubber is set to 2 to 6 mm. The outside diameter of the recessed part 2 is set about 5 mm, the inside diameter L1 is set about 2 to 3 mm, and depth (h) is set about 2 to 4 mm.

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 suitable for being mounted on an ultra-high performance type passenger vehicle, and more particularly to a spew formed corresponding to an air vent hole at the time of vulcanization molding of a tire. It is intended to effectively suppress deterioration of the durability and maneuverability of the tire.

[0002]

2. Description of the Related Art A mold used in vulcanization molding of a tire is provided with a plurality of vent holes for discharging air remaining in the mold during vulcanization molding to the outside. As a result, the product tire taken out of the mold generally has a plurality of rubber projections called Spews corresponding to the holes, which are attached to the tires.

[0003] In order to ship a vulcanized tire as a product, it is necessary to remove the spew because the appearance is poor. Conventionally, a plurality of V-shaped grooves are provided here while the tire is rotated. The spew was cut off by pushing the spew with a cutter having the same.

[0004]

In the cutting of the spew by such a cutter, it is desired that the spew be completely removed from the surface of the tire. However, in practice, some uncut parts are left uncut from the viewpoint of reducing the manufacturing cost. Was usually shipped in a state where it was left. However, the removal of the spew by the cutter as described above,
Since the cutter was to cut with the reaction force of the fall of the spew at the moment it hit the spew, the tip that remained when the spew was cut off,
When an inclined surface having an angle with respect to the tread surface of the tire is formed and such a residual spew exists, not only the contact pressure distribution of the tread becomes non-uniform, but also the shear force may be locally increased. Troubles such as uneven wear occur around the spew, especially for tires with extremely thin tread rubber, such as those used in ultra-high-speed passenger car vehicles, where the tread rubber separates from the belt due to this. Was a concern.

An object of the present invention is to propose a new pneumatic radial tire which can solve the above-mentioned conventional problems caused by the spew, and can be particularly mounted on a vehicle for an ultra-high-speed passenger car.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a pneumatic radial tire having a smooth pattern provided with concave portions for measuring the degree of wear of the tire at a plurality of locations along the rotational direction of the tire and the width direction of the tread. A pneumatic radial tire, wherein a mold air vent hole during vulcanization molding of a tire is disposed at a position corresponding to the concave portion and vulcanization molding is performed. It is particularly preferred that the rubber be an ultra-high performance type tire having a thickness of 2 to 6 mm.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described more specifically with reference to the drawings. FIGS. 1A and 1B show a configuration of a pneumatic radial tire according to the present invention.
(A) shows the tread developed and shown, (b)
Shows a cross section of a main part of the tread.

In FIG. 1, reference numeral 1 denotes a tread, and 2 denotes a concave portion for measuring the degree of wear of the tire. The number of the concave portions 2 is, for example, about 4 to 6 along the width direction of the tread 1, and 6 along the rotational direction of the tire. About several places are provided.

Reference numeral 3 denotes a spew formed on the bottom surface of the concave portion 2 corresponding to the air vent hole of the mold at the time of vulcanization molding of the tire.

Conventionally, air vent holes of a mold are arranged at a plurality of locations corresponding to the tread surface of a tire.
The spew S as shown in FIG. 2 is formed on the surface of the tire after the vulcanization molding, and therefore, it is necessary to cut off the spew S.

The tread rubber according to the present invention has a thickness of 2-6.
Pneumatic tires (dry slick tires for racing, etc.) having a diameter of about mm are provided with an air vent hole at a position corresponding to the recess 2 for abrasion measurement and vulcanization molding of the tire. The spew S shown in FIG. 2 is not formed on the tread surface of the tire removed from the mold.

Although FIG. 1 shows an example in which the spew 3 is formed on the bottom surface of the concave portion 2, an air vent as shown in FIGS. The spew 3 as shown in FIG. 4 or FIG. 5 may be formed on the side wall of the concave portion 2 using the hole 4.

[0013] recess 2 the diameter L in the tread surface is usually about 5 mm, internal diameter L ₁ is approximately 2 to 3 mm, is about 2~4mm for depth h, as spews 3 formed in this case The diameter r is about 1.6 to 2.2 mm, and the height h1 is about ₁ to 3 mm.

In particular, when a structure in which the spew 3 is formed on the side wall of the recess 2 is adopted, it is important to adjust the linear distance from the surface of the tread 1 to the upper end of the spew 3 to about 1 mm. is there.

Since the spew 3 formed in the tire according to the present invention corresponds to the recess 2 of the tire, six recesses 2 are provided in the width direction and the rotation direction (circumferential direction) of the tread of the tire, respectively. In the case, 36 places in total,
That is, 36 tires are provided for each tire. On the other hand, according to the normal manufacturing method, about 30 places are provided in the rotation direction of the tire even if there are six places in the width direction of the tread.
It becomes a book.

In the present invention, the number of spews formed is extremely small as compared with a conventional tire, but in this kind of tire, there is no problem in vulcanization molding due to the reduced number of spews. .

[0017]

EXAMPLE A total of 36 wear measurement recesses (L: 5 m) in the width direction of the tread and in the rotation direction of the tire, a total of 36
m, L ₁ : 2.5 mm, h: 3.5 mm), and the size 255 / 40R17 having a spew as shown in FIG. 1 having a diameter of 1.5 mm and a height of 2.5 mm on the bottom surface of the concave portion. Was manufactured and the contact pressure and circumferential shear force on the spew of the tire were examined (inner pressure of tire: 200 kPa, test load: 2.0 kN). The results were compared with tires manufactured according to the conventional method having a spew on the tread surface (6 tires in the width direction of the tread, 30 tires in the circumferential direction, a total of 180 tires, a height of 0.3 mm in the remaining spew after cutting, and a diameter of 1 tire. The results are shown in Table 1 in comparison with the above results.

[0018]

[Table 1]

Both the contact pressure and the shearing force in Table 1 are comparative values when the conventional tire is represented as an index with 100 as an index. In the tire according to the present invention, both the contacting pressure and the shearing force are extremely small. That was confirmed.

[0020]

According to the present invention, it is possible to minimize the influence of spew, which has been inevitably produced in the vulcanization molding of the tire, so that the tire durability and steering stability can be stabilized. be able to.

[Brief description of the drawings]

FIG. 1 shows a configuration of a pneumatic radial tire according to the present invention, wherein (a) is a development view of a tread,
(B) shows the cross section of the main part.

FIG. 2 shows a configuration of a conventional pneumatic radial tire, in which (a) is a development view of a tread, and (b) is a cross-section of the tread.

FIGS. 3 (a) and 3 (b) schematically show an air vent hole arranged in a vulcanizing mold of a tire.

FIG. 4 is a view showing a side surface of a spew generated when the vent hole of FIG. 3A is used.

FIG. 5 is a view showing a side surface of a spew generated when the vent hole of FIG. 3 (b) is used.

[Explanation of symbols]

 1 tread 2 recess 3 spew S spew

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Claims (2)

[Claims] 1. A smooth-pattern pneumatic radial tire having concave portions for measuring the degree of wear of the tire at a plurality of locations along the rotational direction of the tire and the width direction of the tread, wherein the tire is used at the time of vulcanization molding of the tire. A pneumatic radial tire, wherein a mold air vent hole is arranged at a position corresponding to the concave portion and vulcanized. 2. The pneumatic radial tire according to claim 1, wherein the tread rubber is an ultra-high performance type tire having a thickness of 2 to 6 mm.