JPS6157406A - Tire for airplane - Google Patents

Abstract

PURPOSE:To increase the shock buffering effect of an airplane at its landing and takeoff by arranging each cord of a carcass and a belt layer for the equatorial surface of a tire at a specific angle and forming each cord with the organic fiber cord with the specific pulling modulus of elasticity. CONSTITUTION:A tire T for an airplane consists of a carcass that is composed of two carcass plies 2 and 3 obtained by folding and hooking the end on the circumference of the bead core 1 from the inside to the outside and a carcass ply 4 obtained by folding and hooking the end on the circumference of the bead core 1 from the outside to the inside, belt layer 5 made of organic fiber cords arranged at the outside of the crown section of the carcass, and the band 8. In addition, the cord of the carcasses 2-4 and the belt layer 5 is formed with the organic fiber cord having the pulling modulus of elasticity of less than 5,000kg/ mm.<2> and desirably of less than 1,000kg/mm.<2>. Furthermore, the cord of the carcasses 2-4 is arranged 60-90 deg. for the circumferential direction of the tire and the cord of the belt layer 5 is arranged less than 30 deg. for the circumferential direction of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an aircraft tire that has sufficient load capacity, can withstand aircraft takeoff and landing speeds, and can effectively achieve airframe cushioning.

(Prior Art) Aircraft have made remarkable progress in recent years, and as aircraft weight increases and flight speeds increase, the characteristics of safely taking off and landing at high speeds as well as withstanding high loads and high speeds are becoming increasingly strict. In particular, the following characteristics are required for aircraft tires that differ from general tires.

b) Aircraft tires need to alleviate the impact when an aircraft lands on a runway, stop the aircraft safely, and facilitate takeoff. It is necessary to select reinforcing materials.

Aircraft tires are designed to have a large deflection m under load, for example, about 28% to 38%, in order to effectively cushion the aircraft body and ensure safe takeoff and landing. Therefore, it is necessary to select a tire structure and reinforcing material that can sufficiently withstand large repeated deformations.

c) Since the weight and size of aircraft tires are limited in order to reduce the weight of the aircraft as much as possible, the load on each tire is extremely large.

For example, in a general tire, the load per unit weight in a standard state is about 50 times, whereas in the case of an aircraft tire, it is 130 to 360 times. Also, regarding the internal pressure used, general tires are at most about 8 kg/cnf, while aircraft tires are at about 10 to 1 kg/cnf.
The pressure is extremely high at 6 kg/cnl. Therefore, tires need to be strong enough to withstand this.

As mentioned above, it is necessary for aircraft tires to satisfy all of these required characteristics, but conventionally, this type of tire has often used a cross-ply structure in which the carcass cords are configured to cross each other between the plies. ing. Due to the direction in which the carcass cords are arranged, tires with this type of structure have low rigidity in the trend section, which is unfavorable in terms of wear resistance and heat generation. Furthermore, the center of the trend protrudes due to centrifugal force accompanying high-speed rotation of the tire, causing temporary and permanent tire growth, which is unsatisfactory in terms of tire durability. Therefore, we adopted a so-called radial structure in which carcass cords are arranged in the tire's radial direction, and by placing a belt layer on the inside of the tread in which highly elastic cords are arranged at a relatively shallow angle in the circumferential direction of the tire, we increase the rigidity of the tread. Recently, radial tires have come into use. In this type of radial tire, the carcass cords are arranged in the radial direction, and the high-elastic cords in the belt layer are arranged at a shallow angle in the tire circumferential direction, so the collision rate during takeoff and landing is low. There is a problem that the $1 sum effect is inferior, and there is also a problem that damage occurs due to a large amount of strain at both ends of the belt layer.

(Problems to be Solved) This invention is based on a radial structure that solves the problems of wear resistance, heat generation, and tire growth in the cross-ply structure, and improves the elastic modulus of the carcass cord and the elastic modulus of the belt layer cord. It is an object of the present invention to provide an aircraft tire that improves the effect of mitigating shock during takeoff and landing of an aircraft and prevents damage to both ends of the belt layer, which is a disadvantage of conventional radial structures, by making the belt layer have a specific structure. do.

(Technical Means for Solving the Problems) In this invention, both sides are folded back and locked around a pair of left and right bead cores, and the cord is fixed at an angle of 60° with respect to the tire equatorial plane.
A carcass arranged at an angle of ~90° and a cord placed outside the carcass at an angle of 0° to 30° with respect to the tire equatorial plane.
The carcass and the cords of the belt layer have a tensile modulus of 5000.
This is an aircraft tire characterized by being made of an organic fiber cord having a weight of 1.5 kg/mm" or less.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the right half of the cross-sectional view of the tire of the present invention, and FIGS. 2(a) and 2(b) show schematic views of the belt layer. In the figure, the tire T consists of two carcass plies 2.3, which are secured by wrapping around the bead core 1 from the inside to the outside and folding back the ends. The carcass has a belt layer 5 made of organic fiber cords on the outside of the crown portion of the carcass. Here, the tensile modulus of the cord of the carcass and belt layer is 5000 k
It is composed of organic fiber cords with a weight of less than 1000 kg/mm, preferably less than 1000 kg/mm. As described above, aircraft tires have a large amount of deflection when loaded, and are subject to repeated bending deformation due to high-speed rotation.

Therefore, aircraft tires not only have excellent bending fatigue resistance under large deformations, but also the ply between the carcass and the belt layer due to the difference in stiffness near the boundary between the carcass and the belt layer at both ends. It is important to prevent peeling. Therefore, the present invention provides a carcass ply cord and a belt t-cord.
All four cords have relatively low modulus, especially 5000
By using an organic fiber cord with a weight of less than 100 kg/mm, the bending durability is increased, and the modulus of elasticity of the carcass cord and the belt layer cord are made close to each other, thereby effectively suppressing stress concentration at the end of the belt layer. This made it possible.

Table 1 shows the basic physical properties of cords commonly used as carcass cords and belt layer cords.

In addition to the organic fiber cords listed in Table 1, organic fiber cords used in the present invention include polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, polyacrylonitrile fibers, polyethylene fibers, and polyurethane fibers. Various fibers such as fiber, cellulose fiber, and cellulose ester fiber can be used, and among the above organic fiber cords having a tensile modulus of 1000 kg/mm" or less, such as nylon 66, are particularly preferred.

The carcass cord and the belt layer cord are made of substantially the same material, for example, by using nylon 66 for both the carcass cord and the belt layer cord, the carcass effectively absorbs the repeated impact received from the trend part of the belt layer. This will help prevent damage to the tread.

In addition, in the present invention, since a cord with a relatively low elastic modulus is used for the cord of the belt layer, the "tag effect" of the belt layer is reduced1.
Therefore, according to the present invention, it is preferable to construct the bell) with a folded ply. Here, the folded ply can have various configurations as shown in FIGS. 3(a) to 3(d). Figure 3 (a) shows a structure in which both ends of the ply are folded back to one side, and Figure 3 (b) shows a short folded part TI in which only one end of the ply is folded back to one side.
Figure 3 (C) shows a structure in which only one end is folded back, and the upper and lower ply lengths are approximately the same. Figure 3 (D) shows a structure in which one ply is folded in two places. FIG. 3(E) shows a structure in which both ends of the ply are folded back in opposite directions to form short folded sections Ta and Tb.

In the present invention, a belt layer is formed by mixing one or more of these plies with unfolded plies, and both ends of the belt layer are formed such that the folded portions of the folded plies are located. It is preferable to form.

Next, the cords of the belt layer are arranged at an angle of 30° or less, preferably 10° to 20°, with respect to the tire circumferential direction. Generally, the cord of the belt layer is adjusted from 15 degrees to adjust the "tag effect" and the "engel rope effect" of the trend part.
It was set within a range of 45 degrees, but aircraft tires in particular have a phenomenon in which the tire crown protrudes due to the centrifugal force that accompanies ultra-high speed rotation, and there is a problem with tire growth, and if this phenomenon continues for a long time, the tire will deteriorate. It is permanently set in the growing state, and the heat generation increases, resulting in a significantly reduced durability life.

Therefore, from the above point of view, arranging the cords of the belt layer in a relatively low range with respect to the tire circumferential direction as described above,
Furthermore, it is more preferable to use a band in which the cords are arranged at 0° in the circumferential direction of the tire.

The carcass cords of the present invention have a radial or semi-radial structure arranged at an angle of 60° to 90°, preferably 85° or more, with respect to the tire circumferential direction. Here, two plies with an angle smaller than 90° in the cord angle of the carcass are
If more than one ply is used, it is preferable to arrange the cords so that they intersect between the plies.

In addition, in the present invention, stress concentration at both ends of the belt layer is effectively absorbed by arranging the cushion rubber 6 whose thickness gradually decreases from both ends of the belt layer between the belt layer end and the carcass. , yi can be summed. Cushion rubber 6 has a 300% modulus of 70 to 150 kg/
In the present invention, a tongue-shaped bead apex 7 can be extended from the upper side of the bead core 1 toward the sidewall, but this bead apex 7 has a JIS hardness of 70 to 95 degrees. The height is preferably set within a range of 15 to 50% of the tire cross-sectional height.

Further, in the present invention, the modulus of the topping rubber of the carcass and heald layer is a relatively soft rubber corresponding to the elastic modulus of the cord, for example, a 300% g modulus of 80 to 16.
0kg/cm, preferably 90-110kg/cJIl
range is used.

EXAMPLE Aircraft tires with a tire size of 26 x 6.6 had the basic structure shown in FIG. 1, and tires with various specifications shown in Table 2 were manufactured as prototypes, and the durability of each tire was evaluated. The durability test indicates the number of take-offs and taxi simulations leading to failure according to the TSO-C62C test defined by the National Civil Aviation Administration standard.

In Table 2 showing the evaluation results, Examples 1 and 2 in which nylon 66 was used for both the carcass and the belt layer cord
, polyvarnish f) Lt for the carcass cord, and Example 3 in which nylon 66'c was used for the belt layer cord, all of which were found to pass the durability test standard.

(Effects of the Invention) As described above, the aircraft tire of the present invention uses a specific organic fiber cord with a relatively low elastic modulus for both the carcass cord and the cord of the belt layer, so that it can withstand high speed rotation during takeoff and landing of an aircraft. By effectively achieving cushioning of the aircraft body and suppressing heat generation, an aircraft tire with excellent durability can be obtained.

[Brief explanation of drawings]

Figure 1 shows the right half of the cross-sectional view of the tire of the present invention, and Figures 2 (A), 2 (B), and 3 (A) to 3 (E) show cross-sectional views of the belt layer. . T...Tire, ■...Bead core, 2.3.4...Carcass ply 5...Belt layer 6...Cushion rubber 7...Bead apex Figure 1

Claims (3)

[Claims] (1) Both ends are folded back and locked around a pair of left and right bead cores, and the cord is 60° to 90° to the tire equatorial plane.
A carcass arranged at an angle of 0° and a belt layer disposed outside the carcass and having cords arranged at an angle of 0° to 30° with respect to the tire equatorial plane, the carcass and the cords of the belt layer are arranged at an angle of 0° to 30° with respect to the tire equatorial plane. Tensile modulus is 5000kg/m
An aircraft tire characterized by being made of an organic fiber cord having a diameter of m^2 or less. (2) The tensile modulus of the carcass cord is 1000 kg/
The aircraft tire according to claim 1, which has a diameter of mm^2 or less. (3) The aircraft tire according to claim 1, wherein the belt layer is constituted by a folded ply.