JPS611506A - High internal pressure radial tire - Google Patents

Abstract

PURPOSE:To reduce the weight and enhance the durability in the captioned tire for an aircraft or the like by arranging belt layers consisting of a plurality of plys, which have cords having predetermined modulus of elasticity and contain fold plys, on the outside of the crown part of a carcass. CONSTITUTION:Belt layers 5 consisting of a plurality of plys, which consist of material whose modulus of elasticity is at least 10<5>kg/cm<2> and moreover at least one layer of which consists of a folded ply, are arranged on the outside of a bead core 2, while the bead core 2 is formed by hexagonal beads, in which cords having a cord-strength of at least 300kg/string are bundled into a hexagonal sectional shape. With this constitution, weight of a tire can be reduced and both dimensional stability and durability at high speed running can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high internal pressure radial tire used under high internal pressure, high load, and ultra high speed conditions, such as aircraft tires.

Conventionally, aircraft tires have adopted a bias structure in which the cords of the carcass are arranged so as to intersect with each other between the plies. There are problems such as increased weight and excessive heat generation due to the large number of sheets. On the other hand, if this is made into a radial structure, there will be problems with the reinforcement of the bead portion and the insufficient restraining force of the contact surface against high internal pressure.

As described above, both the conventional bias structure and the radial structure have advantages and disadvantages, and contain many problems that need to be solved.However, the present invention focuses on the fact that the radial structure has a high utilization rate for the carcass, and uses the radial structure. Basically,
They discovered that by improving the material of the carcass cord, the belt layer structure, and the bead structure, it is possible to suppress the increase in tire radius due to centrifugal force during running, and to achieve weight reduction.

For tires that are used under extreme conditions such as high internal pressure, high loads, and extremely high speeds, carcass and bead cores that are strong enough to suppress the expansion of the tire due to high internal pressure are required. The cord tension acting on the carcass is given by the following formula, where: T: Carcass tension at the crown θA: Angle of the carcass cord at the crown (with respect to the tire circumferential direction) a: Crown radius b: Tire maximum width position Radius D: Constant p: Tire internal pressure Here, in the case of a bias structure, the angle of the carcass cord is approximately 45° for 0 people, and the carcass cord angle θA is 90°.
radial structure), the breaking tension TA acting on the carcass becomes large, and it becomes necessary to increase the number of carcass plies.

On the other hand, with a shear structure, the carcass effectively maintains its strength, so the number of plies is small, but the high-speed rotation of the tire that accompanies high-speed driving applies centrifugal force to the tire, which tends to increase the radius of the tire crown. In order to solve this problem, the present invention adopts a radial structure for the carcass, selects steel as the cord material, and adopts a specific belt layer structure.This structure reduces the weight of the tire, improves dimensional stability, and The purpose is to propose a high internal pressure thalassial ear that satisfies high speed durability at the same time.

The present invention includes at least two bead cores in each of the front bead parts, a carcass of steel cords arranged in a radial direction with both ends folded around the bead cores, and a plurality of plies on the outside of the crown part of the carcass. A high internal pressure radial tire characterized in that the cord of the belt layer is made of a material having an elastic modulus of 1015 kg/- or more, and at least one of the belt layers is a fold ply. It is.

In FIG. 1, which explains one embodiment of the present invention based on the drawings, a tire 1 includes one bead core 2 in the bead portion, and a single layer of plywood whose both ends are folded around the bead core. A carcass 4 consisting of: The cords of this carcass are arranged substantially parallel to the tire radial direction, which is a so-called radial structure, and this arrangement direction effectively supports the tension caused by the internal pressure. The carcass cord here is made of steel cord, which maintains high strength. Steel cords that have been conventionally used as carcass cords for heavy vehicle tires can be used; for example, the diameter of the wires is in the range of 0.175u to 0.30u and has a 7x3 twisted structure. . Normally, one Naori-Cu ply is used, but it is also possible to use a plurality of them, and both ends of the ply are folded back around the bead core from the inside to the outside and terminated at the bead portion. In this way, the carcass has a radial structure and the cord is made of high-strength steel, making it possible to increase the strong holding effect, reduce the number of plies, and achieve weight reduction.

Next, the bead core 2 improves the strength of the bead core by bundling a plurality of cords each having a cord strength of 300 kg or more per cord, and further improves the effect of locking the carcass ply by making the bead core hexagonal in cross section. There is. This is because the bead core effectively transmits the driving force transmitted from the wheel rim to the tire body, and its strength is extremely important in maintaining the durability of the tire. Especially in the case of radial structures, Since the tension borne by the carcass ply is larger than that of the bias structure, this is because the material of the bead core itself is strong and it is necessary to increase the locking force at both ends of the carcass ply. It goes without saying that the tire of the present invention can include two or more bead cores. By using such a bead core, the bead portion is strengthened and durability is further improved.

Next, in the present invention, a belt layer 5 is provided on the outside of the crown portion of the carcass.
At least one of the belt layers is a so-called fold ply having a folded end. Here, a schematic diagram of the belt layer used in the tire of the present invention is shown in the second figure.
Figures (A) to (H) show two fold plies F1 and F2 with only one end folded back, and a conventional one. Figure 2 (g) shows various aspects of cut end plies P1 and F2 combinations.
, Fig. 2 (H) uses folded ply with both ends folded back, and Fig. 2 (G) uses one folded ply E1 and three cut end plies P1, F2.
, F3, Figure 2 (H) shows two folded plies E1, F2 and four cut end plies P1, F2,
A combination of F3 and F4 is shown. The cord of the belt layer is made of a material having an elastic modulus of 10E1kg//(n or more, such as steel, aramid, etc.).The cord of the belt layer is usually made of a material having an elastic modulus of 10E1kg//(n or more), such as steel or aramid. Arranged.

In this way, by using the folded structure in which at least one end of the heald i is folded back, it is possible to solve the problem of rubber peeling due to poor adhesion at the end compared to the case of using a conventional cut end ply, and The rigidity of the belt layer is increased. Furthermore, since the cord material has a high elastic modulus of <105 kg/- or more as described above, the hoop effect of the belt layer is significantly enhanced. Furthermore, since the carcass has a radial structure and the cord is made of steel, the iAi series durability and weight reduction can be improved.

In order to confirm the effects of the embodiments of the present invention, specific examples will be explained below.

Regarding aircraft tires with a tire size of 46 x 16.28 ply, a product according to the present invention and a comparative product were manufactured as prototypes according to the specifications shown in Table 1, and the high-speed durability, high-speed durability, and
The amount of change in outer diameter and the amount of crown lift at high speed were measured, and the results are shown in Table 1.

From the table, it can be seen that although the product of the present invention is light in weight, the amount of crown lifting at high speed is small and the product has excellent high speed durability.

In Table 1, (Note 1) High-speed durability was determined by a drum test in which the load was doubled from the standard value, the speed was accelerated from 0 to 225 MP)I in 57 seconds, and the state of damage to the tire was observed.

(Note 2) The amount of outer diameter change is based on the condition inside the mold at an internal pressure of 14°8k.
This is the amount of change in the outer diameter when the internal pressure is filled to g/cal.

(Note 3) The amount of crown lift at high speed is the amount of change in the outer diameter of the crown when accelerating from a stationary state to a speed of 225 MPH.

(Note 4) Kevlar is the trade name of aromatic polyamide fiber. (Note 5) The cross-section of the tire structure is as shown in Figures 1 and 2 (a).

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of the tire of the present invention, and FIG.
FIG. 2(H) is a schematic diagram of the belt layer. 1-tire, 2-bead core, 4--carcass, 5-belt layer, B--band. El, F2, Fl, F2--fold ply, Pl
, F2, F3, F4--Cut end ply. Patent applicant Sumitomo Rubber Industries Co., Ltd. Agent
Patent attorney Tadashi Naemura N ('J
('J N rotation rotation N N N N N *
* Taste Taste

Claims (2)

[Claims] (1) The front bead part is composed of a carcass of steel cords arranged in a radial direction, each containing one bead core and both ends folded around the bead core, and a plurality of plies on the outside of the crown part of this carcass. It has a belt layer, and the cord of this belt layer has an elastic modulus of 10^5.
A high internal pressure radial tire made of a material of kg/cm^2 or more, and characterized in that at least one of the belt layers is a fold ply. (2) The tire according to claim 1, wherein the bead core is a hexagonal bead formed by bundling one cord having a cord strength of 300 kg or more so as to have a hexagonal cross-section.