JPS632701A - Heavy-load radial tire - Google Patents

Abstract

PURPOSE:To improve the separation durability of a carcass ply end section, make a tire lightweight, and reduce its heat emission by arranging a carcass folded end between the innermost layer of belt layers formed into a layer structure with fibers made of specific aromatic polyamide and a carcass layer in a radial tire for aircraft or the like. CONSTITUTION:Belt layers 1 are constituted of multiple layers of plies 3 arranged at an angle of 0 deg.-5 deg. against a tire equator and formed with fiber cords made of aromatic polyamide shown by Equation I. On the other hand, a carcass layer 2 is constituted of radial cord plies arranged in parallel so as to cross the tire equator at an angle of 90 deg.-70 deg., and the wound-up end section 4 of the carcass 2 is put between the innermost layer of the belt layers 1 and the carcass layer 2. According to this constitution, the separation durability of the carcass ply end section is improved, the tire is made lightweight, and its beat emission can be reduced.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to radial tires used under high internal pressure and heavy loads, such as radial tires for aircraft and radial tires for high-speed trains (maglev trains, etc.). It is related to.

(Prior art) Conventionally, tires with a bias structure in which the cords of the carcass are arranged so as to intersect with each other between the braais have been used for such heavy-load radial tires, but in recent years, there has been an increase in fuel efficiency and transportation. In order to improve efficiency, there is an increasing demand for reducing the weight of such heavy-duty radial tires, and radial structures are being considered.

For example, Japanese Patent Application Laid-Open No. 61-60305 discloses that in order to improve high-speed durability, especially to cope with the scunding wave phenomenon at high speeds, cords arranged in a radial direction are arranged substantially parallel to the tire equator on the outside of the crown part of the carcass. A high internal pressure radial tire is disclosed that has a belt layer made up of a plurality of plies with cords arranged in the belt layer. Also, JP-A-61-
Publication No. 71206 discloses that by specifying the elastic modulus of the carcass cord and the elastic modulus of the belt layer cord, and by making the belt layer have a specific structure, the phenomenon in which the crown protrudes due to the centrifugal force accompanying ultra-high speed rotation, that is, the growth of the tire, is disclosed. suppress,
As a result, an aircraft tire has been proposed that enhances the shock-reducing effect during takeoff and landing of an aircraft and prevents damage to both ends of the belt layer.

(Problems to be Solved by the Invention) In a tire with a conventional structure, a large tension is applied to the crown portion at high internal pressure, high load, or high speed, but when a circumferential belt is used, As disclosed in JP-A-6L-7i2Q6 and JP-A-6L-7I2Q6, even if it is made of steel cord, it has a much better hoop effect, and the carcass of the crown part is much better. It can be said that the burden of tension force is reduced. However, a large load is applied to the carcass cord by applying this force to the bead and shoulder portion of the waste, and the carcass cord is subjected to an amount of tension. As a result, the carcass winding portion is pulled in the direction of the bead wire by this amount of tension, so that the tip portion of the carcass is also subjected to a large amount of tension. Normally, various reinforcing materials are added to the bead to prevent distortion at the tip.
As a result, the weight of the tire increased, and the internal pressure was too high, so the separation durability was not sufficient. That is, the prior art has not yet been sufficient to advantageously improve the separation durability at the ends of the carcass ply.

Therefore, an object of the present invention is to improve the separation durability at the end of the carcass ply, while at the same time reducing the weight of the tire.
An object of the present invention is to provide a radial tire for heavy loads that also satisfies low heat generation during high-speed running.

(Means for Solving the Problems) As a result of intensive studies to solve the above-mentioned problems of the prior art, the inventor of the present invention reduced the width growth of the tire by rolling up the tip of the casker winding part up to the belt layer. ,
- On the other hand, we have discovered that by suppressing the rather large diameter growth with a circumferential belt using an aromatic polyamide fiber cord, both the diameter growth and width growth of the tire can be suppressed, and we have completed the present invention.

That is, the present invention has one or more bead cores in each of the bead portions on both sides, a toroidal carcass having at least one or more layers folded and rolled up around the bead core, and a toroidal carcass disposed surrounding the crown portion of the carcass. In a pneumatic radial tire whose main reinforcement is a trend part reinforcing belt, the carcass is composed of radial cord braais arranged parallel to each other in a direction that intersects the tire equator at an angle of 90° to 70°, and the tip of at least one layer of the rolled-up portion of the carcass is disposed between the innermost layer of the belt and the carcass layer, and the belt forms an angle of 0° to 5° with respect to the equator (circumferential direction) of the tire. The following general formula ．． The invention relates to a heavy-duty radial tire characterized by being made of an aromatic polyamide fiber represented by the following formula (an integer of 8 or 10).

In the present invention, when the carcass has multiple layers, it is preferable that the tip of the outermost layer of the rolled up part of the carcass is disposed between the innermost layer of the belt and the carcass layer, and the tip of the rolled up part of the carcass has two or more layers. A tip may be located between the innermost layer of the belt and the carcass layer.

The position where the tip of the carcass winding part is placed between the innermost layer of the belt and the carcass layer may be at the end of the innermost layer of the belt, but since the distortion at the belt end is large, the carcass winding part The length of the tip overlapping the belt layer, that is, the length W between the innermost layer end of the belt and the tip of the carcass layer rolled up to the belt (Fig. 2 (y)) is It is more preferable that it is 10III+ or more in order to improve carcass ply end durability.

The object of the present invention can be achieved by arranging one or more layers (particularly the outermost layer of the winding part) between the belt layers at the tip of the carcass winding part, but this is not preferred because it is difficult to manufacture and the productivity is significantly reduced. No 9-belt tire equator (circumferential direction)
The cord layers arranged at an angle of 0° to 5° with respect to the circumferential belt layer, that is, the belt durability is improved by continuously wrapping the cords from one belt end to the other belt end. Preferable for improving ply end durability.

In the present invention, it is important to use the above-mentioned aromatic polyamide fiber as a belt cord in combination with the carcass structure in order to suppress the diameter growth in the carcass structure.

(Function) In the tire structure of the present invention, since the carcass tip is disposed between the innermost layer of the belt and the carcass layer, there is no need for a reinforcing material at the bead, and the tension in the bead wire direction at the carcass winding section is The tension direction and the tension direction of the inner carcass mutually influence each other, so that they act to be even more effective against growth in the width direction of the tire when the internal pressure is high.

It goes without saying that with such a structure, a sufficiently satisfactory performance can be obtained with respect to the separation durability of the carcass tip, which is the object of the present invention.

Furthermore, in the present invention, unnecessary carcass parts are eliminated from the tire crown, which makes the tire lighter and has a favorable effect on heat generation during high-speed running.

(Example) Next, the present invention will be explained with reference to Examples and Comparative Examples.

As a radial tire for aircraft, size H46x 18
-20 was prototyped.

(a) to (mountain) in FIG. 1 each show a belt structure with a different cord arrangement, and in each case, the widest belt layer is adjacent to the carcass layer, and the width gradually becomes narrower toward the tread side. In the belt structure shown in (a), all the embedded cords of the belt members have an angle α and intersect with each other. (
The belt structure b) consists of a cord layer in which the cords in the belt layer are arranged at an angle of 0° to 5° with respect to the tire equator, that is, a circumferential belt layer. (C)
In the belt structure of 1 or 2 counting from the carcass side,
The belt layer of 3.4.5 consists of circumferential belt layers, and the belt layers of 3.4.5 have cords intersecting each other at a predetermined angle.

The rubber quality, gauge, and number of cords for each belt layer were all the same.

Next, the outline of the radial carcass structure is shown in (X) to (y) of FIG. 2, respectively. (X) shows a conventional structure, in which the tip of the carcass winding section 4 is located at the bead section. (y) and (
Z) shows the carcass structure in the present invention, in which the tip of the carcass winding part 4 is arranged between the belt layer l and the carcass layer 2. In particular, in the carcass structure shown in (Z), the tips of the plurality of carcass winding sections 4 are arranged between the belt layer 1 and the carcass layer 2. The rubber materials used for these carcass were the same, but the material and number of cords were determined so that the total strength of the carcass at the side part was the same. In addition, the angle of the radial carcass with respect to the circumferential direction was 90°, but this angle was 90° to 70°.
It is obvious that it can be changed up to ゜.

Hereinafter, the specific structure of the aircraft radial tire prototyped in each Example and Comparative Example and the various performances of the tire obtained through the tire tests shown below will be described.

After assembling the Dango 2 Sumikyu folded tire on the rim and pressing it against the drum with an internal pressure of 15.0 kg/cm" and a load of 20 tons, the drum was set at a speed of OK.
m/h to 3601v/h in 70 seconds. 3
After reaching a speed of 60 km/h, the load was removed and the tire was cooled to a constant temperature. The same test was repeated to determine how many times it could withstand. Here, tires that have not failed up to 50 times are indicated as OK level in Table 1 below.

■Danjijo closed tires were mounted on rims, pressed against a drum at an internal pressure of 15.0 kg/cm" and a load of 20 tons, and run continuously at a speed of 16 km/hour. Total mileage until failure ( km) and confirmed the location of the failure at the same time.

3) Tire internal pressure Okg/c+m" to '15kg/cm"
The maximum width of the tire side when raised to the maximum width is shown as a rate of change.

After assembling the J & Shun tire on the rim, water was injected into it, and the water pressure value at the time of destruction was displayed.

Stop comparison±The angle α with the circumferential direction of the belt shown in Figure 1 (al) is 10'
The number of cords to be inserted was 30 and 15 cm. The cord material Kevlar shown in Table 1 below is the trade name of aromatic polyamide manufactured by DuPont. The twist structure of the belt cord is 3000d/3, and the number of first and second twists is 20 times/l0cm, and the first and second baths are epoxy and resorcin-formaldehyde/latex (hereinafter referred to as r).
l? F/L J) was used. This treatment was carried out in the same manner in all of the following Examples and Comparative Examples. Other structural features are shown in Table 1.

The prototype aircraft radial tire combines the conventional cross-belt structure shown in Fig. 1(a) with the type of carcass structure shown in Fig. 2(y). As can be seen, the high-speed durability was not sufficient due to the crossed belts, and failures also occurred at the winding section.

Flame-stopping flame 1 The material of the belt cord was 6.6-nylon, and the twisting structure was that two 1890 d yarns were twisted together and then twisted, and then two more 1890 d yarns were twisted.
//2/2). The number of first and second twists is 20 times/10c each.
M closed. The obtained code was subjected to RF in the same manner as in Comparative Example 1.
It was heat-treated in a tube. Other structural features are shown in Table 1.

This aircraft radial tire uses a circumferential belt as the belt layer, but the material of the belt cord is 6,6-nylon and the carcass structure is a conventional one, as can be seen from the test results in Table 1. As a result, the separation durability at the rolled-up end was insufficient, and the tire width grew too much.

On the sludge: - As shown in Table 1, Kevlar was used as the belt cord material in Examples 1 and 3, and Hto50 (trade name of aromatic polyamide fiber manufactured by Kijinsha) was used in Example 2. . here,
Kevlar has a chemical structure represented by the following formula; % formula %, and HM-50 has the following formula;
It has a chemical structure represented by (in the formula, m:n=50:50). In addition, for the belt structure, in Examples 1 and 2, a full-thickness circumferential belt as shown in FIG. 1(b) was used,
In Example 3, a combination of a circumferential belt and a cross belt as shown in FIG. 1(C) was used.

- On the other hand, the carcass structure of Examples 1 to 3 is as shown in FIG. 2 (Y), and the material of the carcass cord is Kevlar in Examples 1 and 3, and H
It was set as 50. Other structural features are shown in Table 1.

As shown in Table 1, the results of tire performance tests conducted on the aircraft radial tires of these examples showed that the performance of all tires, such as high-speed durability and separation durability at the winding part, was fully satisfactory. It was found to be at the level of actual use.

From Example 3, it was confirmed that sufficient tire durability could be obtained even if the belt structure was of the type shown in FIG. 1 (C1).

The aircraft radial tires of Kitamoto "Reyu" 11 Kodo Comparative Example 3 and Example 4 both had carcass structures of the type shown in Figure 2 (Z), and the material of the carcass cords were both 6.6. -Made of nylon. However, the material of the belt cord is comparative example 3.
In Example 4, 6,6-nylon was used, and in Example 4, Kepler was used.

As a result of tire performance tests conducted on these aircraft radial tires, it was confirmed that the tire of Example 4 was at a sufficient level in terms of durability, although it was slightly disadvantageous in terms of tire weight. On the other hand, in the tire of Comparative Example 3, as a result of using 6.6-nylon as the belt cord material,
Since distortion also occurs in the crown portion, durability was still insufficient even if the tip of the rolled-up portion of the carcass was disposed between the innermost layer of the belt layer and the carcass layer.

(Effects of the Invention) As explained below, in the heavy-duty radial tire of the present invention, aromatic polyamide fibers are used in the circumferential belt,
In addition, by arranging the tip of the carcass winding part between the innermost layer of the belt and the carcass layer, the separation durability at the end of the carcass ply is improved, and at the same time,
The effect of achieving sufficient tire weight reduction and low heat generation at high speeds can be achieved.

[Brief explanation of the drawing]

+a) to (C) in Fig. 1 are partial plan views showing the belt structure, and (X) to (Zl) in Fig. 2 are schematic views showing the cross-sectional structure of the carcass, respectively. 1... Belt layer 2...Carcass layer 3...
・Bead core 4...Carcass winding part

Claims (1)

[Claims] 1. A toroidal carcass having one or more bead cores in each of the bead portions on both sides, at least one or more layers of toroidal carcass folded and wound around the bead cores, and surrounding the crown portion of the carcass. In a pneumatic radial tire whose main reinforcement is a tread reinforcing belt, plies of radial cords are arranged parallel to each other in a direction in which the carcass intersects the equator of the tire at an angle of 90° to 70°. and the tip of at least one layer of the rolled up portion of the carcass is disposed between the innermost layer of the belt and the carcass layer, and the belt is at an angle of 0° to 5° with respect to the equator (circumferential direction) of the tire. It has at least one code layer arranged at an angle, and the code used in this code layer has the following general formula, ▲mathematical formula, chemical formula, table, etc.▼ (In the formula, Ar_1 is ▲mathematical formula, There are chemical formulas, tables, etc.▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, Ar_2 is ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ Mathematical formulas, A heavy-duty radial tire characterized by being made of aromatic polyamide fiber represented by the chemical formula, table, etc.▼, x is an integer of 4, 6, 8, or 10.