JP4151758B2 - Pneumatic tire - Google Patents

Description

【００２７】
上記表１に示すように、本発明に係る実施例の空気入りタイヤにおいては、従来例に比して亀裂の発生が大幅に抑えられることが確認できた。
【００２８】
【発明の効果】
以上説明してきたように、本発明によれば、ビードコア周りの耐セパレーション性を向上して、カーカスプライ間の亀裂に伴う故障の発生を大幅に抑制することができる。本発明の空気入りタイヤは、大型ローダー等の建設車両における上記故障の防止に特に効果的である。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る空気入りタイヤを示す左半分断面図である。
【図２】ビードコアの切断面を示す拡大図である。
【図３】ラッピングテープを示す概略拡大断面図である。
【符号の説明】
１ トレッド部
２ サイドウォール部
３ ビード部
４ ビードコア
５ カーカスプライ群
６ カーカス
７ ダウンプライ群
８ ビードベース
９ ラッピングテープ
１０ 補強コード
１１ 被覆ゴム[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire (hereinafter also simply referred to as “tire”), and more particularly to a pneumatic tire that is excellent in separation resistance around a bead core and can be suitably used in construction vehicles such as large loaders.
[0002]
[Prior art]
Since tires for construction vehicles such as large loader tires are required to withstand use under harsh usage conditions, various studies have been made and improvements have been made to improve their durability and durability. It has been.
[0003]
[Problems to be solved by the invention]
In particular, as a problem associated with use under high load, there is a risk of separation failure between carcass plies due to a large torque acting on the tire during operation of the vehicle. This is because the carcass ply moves in the circumferential direction due to the torque from the vehicle, but the bead core does not move, so shear strain occurs between them, causing separation between the bead core and the wrapping tape, This separation eventually progresses to the carcass ply, leading to failure.
[0004]
The wrapping tape is used to reinforce the bead core by being wound around a wire forming the bead core. Generally, in a conventional tire for a large vehicle, the reinforcing cord diameter is 40 to 60% of the carcass cord diameter, and the covering rubber is used. The gauge used was 0 to 0.09 mm and the hardness (HD) was 80 to 130% of the carcass coating rubber HD.
[0005]
Recently, in large construction vehicles, particularly loaders, higher torque is being promoted in order to improve work efficiency, such as improving excavation force and shortening travel time. Accordingly, since the torque applied to the tire increases as the vehicle torque increases, the frequency of occurrence of a separation failure between the bead core and the wrapping tape as described above has increased.
[0006]
Accordingly, an object of the present invention is to solve the above problems and improve the separation resistance around the bead core, thereby favorably suppressing the occurrence of a separation failure between the carcass plies, and suitable for construction vehicles such as large loaders. The object is to provide a pneumatic tire that can be used.
[0007]
[Means for Solving the Problems]
Usually, as a measure against a case-related failure, it is conceivable to increase the number of plies and improve the internal pressure. However, this is an effective measure because it increases direct material costs and processing costs. Absent. Therefore, as a result of intensive studies, the inventor has improved the bead core around the wrapping tape, which is currently the core of the failure, and can solve the above problem without causing an increase in cost. As a result, the present invention has been completed.
That is, in order to solve the present invention, the pneumatic tire of the present invention is as follows.
[0008]
(1) In a pneumatic bias tire having a plurality of pairs of bead cores and a plurality of carcass ply groups corresponding to the number of bead core pairs, the carcass plies made of ply cords are wound around the plurality of pairs of bead cores.
A wrapping tape is wound around the bead core, the reinforcing cord diameter of the wrapping tape is 65 to 150% relative to the carcass cord diameter, the gauge of the coated rubber is 0.10 to 0.3 mm, and the JIS Shore A hardness is carcass. Coated rubber JIS Shore A is a pneumatic tire having a hardness of 140 to 220% relative to the hardness.
[0009]
(2) In the pneumatic tire of (1), the maximum tire load capacity (W) is 40 tons or more, the traction force (T) per vehicle is 45 tons or more, and the maximum tire load capacity (W ) And traction force (T) per vehicle (T / W) is a pneumatic tire used for a large construction vehicle having a ratio of 1.1 or more.
[0010]
(3) The pneumatic tire according to (1) or (2), wherein the pneumatic tire has three or more pairs of the bead cores.
[0011]
(4) The pneumatic tire according to any one of (1) to (3), wherein the thickness of the cord of the carcass cord is 1260 denier or more.
[0012]
(5) The pneumatic tire according to any one of (1) to (4), wherein an intersection angle of the carcass cord with respect to a tire equator plane is 50 to 60 °.
[0013]
(6) In the pneumatic tire according to any one of (1) to (5), the carcass ply is a pneumatic tire provided with 10 or more per bead core.
[0014]
According to the inventions of the above (1) to (6), the diameter of the reinforcing cord of the wrapping tape is made larger than that of the conventional one and the gauge of the covering rubber is made larger, so that the distortion generated between the carcass ply and the bead core is reduced. This concentration can be avoided by setting the hardness of the coated rubber higher than in the past, so that the concentration of the distortion can be avoided, so that the separation between the bead core and the wrapping tape caused by the distortion can be avoided. It became possible to prevent well.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a left half sectional view showing a pneumatic tire according to an embodiment of the present invention. Reference numeral 1 denotes a tread portion and reference numeral 2 extends radially inward from a side portion of the tread portion 1. Reference numeral 3 denotes a side wall portion, and reference numeral 3 denotes a bead portion located on the inner peripheral side of the side wall portion 2.
[0016]
In the illustrated example, three pairs of bead cores 4 are disposed in the bead portion 3, and a carcass 6 including a carcass ply group 5 of inner and outer layers and a down ply group 7 of one layer is interposed between these bead cores. It extends to the toroidal and forms the skeleton structure of the tire. Each of the carcass ply groups 5 is configured by winding and arranging the side portions of a plurality of carcass plies made of ply cords around the bead core 4 from the inner side to the outer side in the tire width direction. In the illustrated example, the down ply group 7 located on the outermost side is configured by arranging side portions of a plurality of carcass plies, which are also formed of ply cords, along the bead base 8 of the tire. Yes.
[0017]
As shown in an enlarged view in FIG. 2, a wrapping tape 9 is wound around the bead core 4. FIG. 3 is a schematic enlarged sectional view of the wrapping tape 9. In the present invention, it is important that the diameter L of the reinforcing cord 10 of the wrapping tape 9 and the gauge x and hardness (HD) of the covering rubber 11 satisfy the following conditions, respectively.
[0018]
The reinforcing cord diameter L of the wrapping tape 9 is 65 to 150%, preferably 90 to 110%, compared to the carcass cord, that is, the ply cord diameter of the carcass ply. By increasing the diameter of the reinforcing cord compared to the conventional 40 to 60% and improving the rigidity, the distortion generated between the carcass ply and the bead core can be alleviated, and the separation around the bead core due to the distortion is achieved. Can be prevented appropriately. If the reinforcing cord diameter L is less than 65% relative to the carcass cord diameter, the rigidity is too small to sufficiently obtain a strain relaxation effect. On the other hand, if the reinforcing cord diameter L exceeds 150%, the rigidity becomes too high and manufacturing becomes difficult. .
[0019]
The gauge x of the covering rubber 11 of the wrapping tape 9 is 0.10 to 0.3 mm, preferably 0.11 to 0.20 mm. By ensuring the covering rubber gauge x larger than the conventional 0-0.09 mm, the strain relaxation effect can be further enhanced. If the coated rubber gauge x is less than 0.10 mm, the effect of strain relaxation is not sufficient, while if it exceeds 0.3 mm, the flow of rubber increases during production, which makes production difficult.
[0020]
Furthermore, the JIS Shore A hardness of the covering rubber 11 of the wrapping tape 9 is 140 to 220%, preferably 145 to 160% as compared with the carcass coating rubber JIS Shore A hardness. By setting the coating rubber hardness higher than the conventional 80 to 130%, it is possible to avoid the concentration of distortion around the bead core and appropriately prevent the occurrence of separation. If the coating rubber hardness is less than 140%, it is too soft and the concentration of distortion due to the circumferential movement of the carcass ply occurs, which tends to cause separation. On the other hand, if it exceeds 220%, the wrapping tape 9 is wound around the bead core 4. Is difficult to manufacture.
[0021]
The pneumatic tire of the present invention has a tire maximum load capacity (W) of 40 tons or more, a traction force (T) per vehicle of 45 tons or more, and a tire maximum load capacity (W) of 1 It can be suitably used for large construction vehicles in which the ratio (T / W) to the tractive force (T) per table is 1.1 or more. That is, the present invention has a great merit in that a separation failure can be satisfactorily prevented even in such a large vehicle in which high torque is likely to be generated.
[0022]
In the present invention, the carcass cord of the carcass ply 5 is preferably disposed at an angle of 50 to 60 ° with respect to the tire equatorial plane, and the thickness of the cord is preferably 1260 denier or more. It is. Furthermore, it is preferable that the carcass ply 5 is disposed with 10 or more per bead core. By these, the arrangement | positioning conditions of a carcass ply can be optimized and the effect of this invention can be acquired more favorably.
[0023]
In the present invention, as long as the above conditions are satisfied, the material and other physical properties of various members such as the reinforcing cord and covering rubber of the wrapping tape, the ply cord and coating rubber of the carcass ply are particularly limited. It can be determined appropriately according to common usage.
[0024]
【Example】
Hereinafter, the present invention will be described in detail using examples.
Two test tires were produced according to the following specifications, and a field test was conducted. The bead core was covered with a wrapping tape having the structure shown in Table 1 below.
Tire size: ORS 555 / 80-57 62PR
Carcass material used: 66 nylon, cord thickness: 1260 denier, 4-bead configuration Carcass configuration: 4 groups of carcass plies (14 each, intersection angle of the ply cords to the tire equator (αm) (first group): 54 ° , (Second group): 56 °, (third group): 56 °, (fourth group): 58 °) + down ply (6 sheets, angle of intersection of the ply cord with the tire equator (αm): 55 °)
[0025]
Evaluation of the field test was carried out by mounting each test tire on a construction vehicle (20 m ³ bucket wheel loader) at a pressure of 700 kPa, pulling it up after 2000 hours by the user, and performing an anatomical check. The results are shown by indexing the crack length around the bead core. The larger the index is, the larger the crack is, and when the index is 100, the entire bead core is separated. The evaluation results are also shown in Table 1 below.
[0026]
[Table 1]

[0027]
As shown in Table 1 above, in the pneumatic tire of the example according to the present invention, it was confirmed that the occurrence of cracks was significantly suppressed as compared with the conventional example.
[0028]
【The invention's effect】
As described above, according to the present invention, the separation resistance around the bead core can be improved and the occurrence of a failure due to a crack between the carcass plies can be significantly suppressed. The pneumatic tire of the present invention is particularly effective in preventing the above-described failure in construction vehicles such as large loaders.
[Brief description of the drawings]
FIG. 1 is a left half sectional view showing a pneumatic tire according to an embodiment of the present invention.
FIG. 2 is an enlarged view showing a cut surface of a bead core.
FIG. 3 is a schematic enlarged sectional view showing a wrapping tape.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Carcass ply group 6 Carcass 7 Down ply group 8 Bead base 9 Wrapping tape 10 Reinforcement cord 11 Cover rubber

Claims (6)

In a pneumatic bias tire having a plurality of pairs of bead cores and a plurality of carcass ply groups according to the number of bead core pairs, the carcass plies made of ply cords are wound around the plurality of pairs of bead cores.
A wrapping tape is wound around the bead core, the reinforcing cord diameter of the wrapping tape is 65 to 150% of the carcass cord diameter, the gauge of the coated rubber is 0.10 to 0.3 mm, and the JIS Shore A hardness is carcass. A pneumatic tire characterized in that the coating rubber is 140 to 220% relative to JIS Shore A hardness.   The maximum tire load capacity (W) is 40 tons or more, the traction force (T) per vehicle is 45 tons or more, and the ratio between the maximum tire load capacity (W) and the traction force (T) per vehicle The pneumatic tire according to claim 1, which is used for a large construction vehicle having a (T / W) of 1.1 or more.   The pneumatic tire according to claim 1, wherein the pneumatic tire has three or more pairs of the bead cores. The pneumatic tire according to any one of claims 1 to 3, wherein a thickness of the carcass cord is 1260 denier or more.   The pneumatic tire according to any one of claims 1 to 4, wherein an intersection angle of the carcass cord with respect to a tire equatorial plane is 50 to 60 °.   The pneumatic tire according to any one of claims 1 to 5, wherein the carcass ply is disposed with 10 or more per bead core.

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