JPH0732813A - Green tire - Google Patents

Abstract

(57) [Summary] [Objective] The present invention controls the thickness of the inner liner at the time of production to a uniform thickness by making the inner liner before vulcanization molding into an appropriate shape corresponding to each part of the tire to reduce the weight. The purpose is to complete a green tire that can achieve The green tire 1 of the present invention has an air-impermeable inner liner 3 adhered to the entire inner peripheral surface of a toroidal radial tire casing 2 having an average thickness of a crown central portion 4 of T1 and a shoulder. When the average thickness of the portion extending from the portion 5 to the portion 6a of the sidewall 6 is T2, and the average thickness of the remaining portion 6b of the sidewall 6 is T3, T2 = 1.3 × T1 to 2.2 × T1, T3 = It is characterized in that it is formed by extrusion in a relationship of 0.8 × T1 to 1.0 × T1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a green tire capable of reducing the weight of a pneumatic radial tire.

[0002]

2. Description of the Related Art Pneumatic radial tires are provided with an air impermeable inner liner on the entire inner peripheral surface of a tire casing to maintain air pressure. This inner liner is usually made of a flat sheet and has a uniform thickness in the width direction as shown in FIG. 3a before vulcanization molding.

[0003]

However, even if the inner liner 33 has a uniform thickness before being vulcanized and molded, the vulcanized and molded product has a non-uniform thickness as shown in FIG. 3C. Tended to be. The inner liner 33 'at the time of production must have a thickness necessary to prevent the air filled in the tire from permeating, and therefore,
It is advantageous for reducing the weight of the tire to make the inner liner 33 'uniform in thickness when manufactured. The cause of uneven thickness of the inner liner is that the expansion rate of each part of the tire is different by shaping from flat to toroidal at the time of molding, or the bladder (barrel shape) used to maintain the tire internal pressure during vulcanization. The force of pressing the inner liner of the rubber bag) is not uniform. Therefore, in order to make the thickness of the inner liner in the product uniform, it is important to control the thickness of the inner liner corresponding to each part of the tire caused by shaping during vulcanization molding.

Therefore, according to the present invention, by forming the inner liner before vulcanization molding into a proper shape corresponding to each part of the tire, it is possible to control the thickness of the inner liner at the time of production to be a uniform thickness and reduce the weight. The purpose is to complete the tire.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the average thickness of the crown center portion is T1 and the shoulder portion is T1 for the air impermeable inner liner adhered to the entire inner peripheral surface of the toroidal radial tire casing. To T2 and the average thickness of the remaining portion of the sidewall is T3, T2 = 1.3 × T1 to 2.2 × T1, T3 = 0.8 × T1 A green tire formed by extrusion with a relationship of 1.0 × T1. In addition, here, the central portion of the crown corresponds to a central portion of the crown portion corresponding to about 50 to 80% of the tread width, and the shoulder portion extends from the end of the central portion of the crown to the buttress of the tire, that is, the upper portion of the sidewall, the sidewall. Is part of the maximum width of the tire from the end of the shoulder part, and the remaining part of the sidewall is
The range is from the edge of the sidewall portion to the tip of the bead.

FIG. 1a shows a cross section in the width direction of a typical green tire according to the present invention. In the figure, 1 is a green tire, 2 is a tire casing, 3 is an inner liner, 4
Is a central portion of the crown, 5 is a shoulder portion, 6 is a side wall, 6a is a part of the side wall, and 6b is a remaining part of the side wall. Green tire 1 shown in FIG. 1a
Is provided with an air impermeable inner liner 3 which is adhered to the entire inner peripheral surface of a tire casing 2 having a toroidal radial structure. The inner liner 3 before being attached to the inner peripheral surface of the tire casing 2 has a cross-sectional shape as shown in FIG. 1a, and has a crown central portion 4, a portion 6a extending from the shoulder portion 5 to a part of the sidewall 6,
The thickness corresponding to the remaining portion 6b of the sidewall 6 is adjusted so that the relationship of T2 = 1.3 × T1 to 2.2 × T1, T3 = 0.8 × T1 to 1.0 × T1 is established.

[0007]

As described above, the conventional inner liner made of a flat sheet having a uniform thickness has a non-uniform thickness at the time of manufacture because the expansion rate due to shaping in vulcanization molding is different in each part of the tire. is there. Therefore, the present inventors performed vulcanization molding using a conventional inner liner made of a flat sheet, and by measuring the thickness distribution of the inner liner of each part of the product tire, the inner liner of the product tire is It was found that each had a different thickness change rate.
FIG. 2A is a width cross section of the product tire at that time, and FIG. 2B is a plot of the thickness of the inner liner at the position of each part of the tire shown in FIG. From these figures, it was found that the thickness of the inner liner at the time of manufacture was different in each part of the tire, and particularly the part 6a extending from the shoulder part 5 to a part of the sidewall 6 was thin. Therefore, in the present invention, by disposing the inner liner 3 having the cross-sectional shape as shown in FIG. 1b on the entire inner peripheral surface of the tire casing 2 having the toroidal radial structure, the inner liner 3'of the product is manufactured. The thickness can be uniform as shown in Figure 1c. Specifically, the average thickness T1 of the crown center portion 4, the average thickness T2 of the portion extending from the shoulder portion 5 to the portion 6a of the sidewall 6, and the average thickness T3 of the remaining portion 6b of the sidewall 6 are given by T2 = The relationship is 1.3 × T1 to 2.2 × T1, T3 = 0.8 × T1 to 1.0 × T1. In order to bring the thickness of the inner liner 3 before vulcanization molding into the above relationship, it is preferable to use an extrusion die having a contour shape as shown in FIG. 2c.

[0008]

EXAMPLE A specific example of the green tire according to the present invention will be described with reference to FIG. The first embodiment includes an air impermeable inner liner 3 adhered to the entire inner peripheral surface of a tire casing 2 having a toroidal radial structure. The inner liner 3 before being attached to the inner peripheral surface of the tire casing 2 has a cross-sectional shape as shown in FIG. 1a, and the thickness T1 of the crown central portion 4 is 0.5 m.
m, the thickness T2 of the portion 6a extending from the shoulder portion 5 to a part of the sidewall 6 is 0.8 mm, the sidewall 6
The remaining portion 6b has a thickness T3 of 0.5 mm. At this time, T2 = 1.6 × T1 and T3 = 1.0 × T1. The tire casing 2 has a conventional structure including a one-ply carcass, a two-layer belt including a rubberized layer of steel cord, and a tread portion. This green tire was subjected to a test using a vulcanized pneumatic tire.
The size of this pneumatic tire is 185 / 70R14.

In the second embodiment, the thickness T1 of the crown central portion 4 is
Is 0.8 mm, the thickness T2 of the portion 6a extending from the shoulder portion 5 to a part of the sidewall 6 is 1.1 mm, and the thickness T3 of the remaining portion 6b of the sidewall 6 is 0.7 mm, where T2 = 1.4. × T1, T3 = 0.9 × T
It has the same structure as in Example 1 except that the relationship of 1 is satisfied.

In the conventional example 1, the thickness T of the central portion 4 of the crown is
1. The thickness T2 of the portion 6a extending from the shoulder portion 5 to a part of the sidewall 6 and the thickness T3 of the remaining portion 6b of the sidewall 6 are the same as in Example 1 except that the thickness T2 is 1.2 mm. Have a structure.

Tests were conducted on air permeability and tire weight. Table 1 shows the test results. The air permeability is
The tire weight is shown as an index ratio with 100 as the conventional tire, and the tire weight is shown as an increase or decrease percentage based on the conventional tire.

[0012]

[Table 1]

From the test results, the air permeability of Examples 1 and 2 is the same as that of the conventional example, and the weight of the tire is 3 to 4%.

[0014]

According to the present invention, the inner liner 3 having a cross-sectional shape as shown in FIG. 1b is provided on the entire inner peripheral surface of the tire casing 2 having a toroidal radial structure, so that the inner liner at the time of manufacture is manufactured. The thickness of the liner 3'can be made uniform as shown in Figure 1c. Specifically, the average thickness T1 of the crown central portion 4, the average thickness T2 of the portion extending from the shoulder portion 5 to the portion 6a of the sidewall 6, and the average thickness T3 of the remaining portion 6b of the sidewall 6 are given by T2 = The relationship is 1.3 × T1 to 2.2 × T1, T3 = 0.8 × T1 to 1.0 × T1. By making it possible to make the thickness of the inner liner 3'uniform when the product is manufactured, the inner liner 3'can be made thinner than the conventional product, which leads to an improvement in fuel efficiency due to a lightweight tire.

[Brief description of drawings]

1 is a widthwise sectional view of a representative green tire 1 according to the present invention, b is a widthwise sectional view of an inner liner 3 before being attached to a tire casing 2 of a, and c [Fig. 3] is a widthwise sectional view of a pneumatic tire 7 obtained by vulcanizing and molding the green tire 1 of a.

FIG. 2a is a cross-sectional view in the width direction of a conventional pneumatic tire vulcanized and molded using a conventional inner liner made of a flat sheet, and b is a cross-sectional view of the inner liner in each part of the pneumatic tire of a. It is the figure which plotted thickness distribution, c is an extrusion die which has a contour shape for manufacturing the optimal inner liner used for the green tire of the present invention based on the result of b.

FIG. 3A is a cross-sectional view in the width direction of a conventional green tire 11, b is a cross-sectional view in the width direction of an inner liner before being attached to the tire casing 2 of a, and c is
It is a width direction sectional view of the pneumatic tire 8 obtained by vulcanizing and molding the green tire 11 of a.

[Explanation of symbols]

 1,11 Green tire 2 Tire casing 3,33 Inner liner 3 ', 33' Inner liner (at the time of product) 4 Crown center part 5 Shoulder part 6 Side wall 6a Part of side wall 6b Remaining part of side wall 7,8 Air Tires

Claims (1)

[Claims] 1. An average thickness at the center of the crown of an air impermeable inner liner adhered to the entire inner peripheral surface of a tire casing having a toroidal radial structure is T.
1, the average thickness of the portion extending from the shoulder portion to a part of the sidewall is T2, and the average thickness of the remaining portion of the sidewall is T3, T2 = 1.3 × T1 to 2.2 × T1, T3 = 0. A green tire formed by extrusion with a relationship of 8 × T1 to 1.0 × T1.