JP4315509B2 - Pneumatic tire and manufacturing method thereof - Google Patents

Description

【００２６】
表１から明らかなように実施例タイヤ１では、カーカスプライ巻き上げ端のセパレーションのおそれを十分に除去し得ることから、巻き上げ部近傍のスティフナおよびサイドゴムのボリュームを下げることにより、比較タイヤよりもタイヤ重量を有効に低減させることができ、またカーカスコードの折返し部の、他のカーカスコードとの交差部を９個所としたことにより、比較タイヤおよび従来タイヤのいずれよりもビード部耐久性を大きく向上させることができた。
そしてとくに、実施例タイヤ２では、ビード部の補強構造を簡素化したことにより、 従来タイヤに比較してもタイヤ重量を有効に低減させることができた。
【００２７】
【発明の効果】
上記実施例からも明らかなように、この発明によれば、タイヤ重量の一層の低減を実現してなお、ビード部耐久性を十分に向上させることができる。
【図面の簡単な説明】
【図１】 この発明の実施の形態をタイヤの半部について示す子午線断面図であある。
【図２】 カーカスプライの部分展開図である。
【図３】 最少コード本数のカーカスプライの部分展開図である。
【図４】 従来タイヤ２のカーカスプライの、部分展開図である。
【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
６ カーカスプライ
７ プライ本体部分
８ 巻上げ部
１０ カーカスコード
１１ 交差部
ｎ 任意本数
Ｄ 中心距離
ｄ コードピッチ
ｐ タイヤ周方向の距離[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly to a pneumatic radial tire for heavy loads and a method for manufacturing the same, and in particular, the durability of the bead portion is greatly improved while the tire weight is effectively reduced. .
[0002]
[Prior art]
In conventional pneumatic tires, both sides of a carcass made of at least one carcass ply are wound and fixed around a bead core disposed in the bead, and the carcass plies here are arranged in parallel in a straight line. It is constituted by a sheet cutting member obtained by applying a rubber film with a calender to a large number of carcass cords.
[0003]
For this reason, the carcass ply, and thus the carcass winding end, inevitably has low adhesion to the surrounding rubber, and therefore, when the tire is subjected to load transfer, a large amount of repetition from the bead portion to the sidewall portion occurs. Due to the distortion generated in the vicinity of the carcass winding end due to the bending deformation, there is a disadvantage that the winding end is easily separated from the surrounding rubber.
[0004]
Therefore, in many cases, for the purpose of reducing distortion generated in the vicinity of the carcass winding end, the area from the bead portion to the sidewall portion is reinforced with various reinforcing members to increase the rigidity of those portions. .
[0005]
[Problems to be solved by the invention]
However, particularly in the case of pneumatic radial tires for heavy loads, it is still impossible to achieve a satisfactory bead portion durability by such measures, and the arrangement of various reinforcing members is not possible. There has been a problem of obstructing demands for weight reduction and low cost.
On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 9-156310, air having a carcass passing through the tire body from the tread portion through the sidewall portions on both sides of the tire to the bead portion having the bead core. In the case where a carcass ply is formed by turning the carcass cord alternately at a number of turning points arranged in the circumferential direction on both sides of the tire and sequentially turning the turning points in the circumferential direction. In addition to improving the adhesion between the cord and rubber at both ends of the carcass ply, it is possible to reduce and disperse the stress acting on both ends of the ply, greatly improving the bead durability and achieving weight reduction. .
[0006]
However, in this disclosed technique, the folded portion of each carcass cord is made to intersect with other carcass cords at one place or two places, and the number of intersections where stress acting on the carcass cords is concentrated is small. The strain per intersection is large, and the stress acting on the carcass cord of the tire as a pressure vessel cannot be sufficiently dispersed and supported by other carcass cords. The distribution of the intersections of the carcass cords at the turn-back portions is uneven, and the stress acting on each carcass cord cannot be distributed and supported evenly over the entire circumference of the tire. As a result, the carcass cord A particularly large distortion will occur at the intersection of the beads, and the durability of the bead portion is high enough to be expected. There is a problem that can not be Rukoto.
[0007]
The present invention is an improvement of the above disclosed technique, in which the stress acting on the carcass cord is distributed and supported by more carcass cords, and more preferably the stress acting on the carcass cord is added to the tire circumferential direction. Accordingly, a pneumatic tire and a method of manufacturing the same are provided, in which the weight of the tire is reduced and the durability of the bead portion is greatly improved.
[0008]
[Means for Solving the Problems]
A pneumatic tire according to the present invention includes a carcass made of a carcass ply that reaches a bead part from a tread part through a wall part, and at least one carcass ply straddles a pair of bead parts and a ply main body part that is continuous with a toroid. Each of a plurality of carcass cords extending substantially in the tire meridian direction at the ply main body portion at the respective winding portions. The center distance D before and after the folding of each of a plurality of n pairs of carcass cords is 2n times the cord pitch d under the arrangement state of all carcass cords. In addition, the plurality of carcass cords of the first n-th pair are set to be twice the cord pitch d in the tire circumferential direction The second pair of n + 1 and subsequent carcass cords are disposed between the plurality of n pairs of carcass cords in the opposite direction to the cords at a cord pitch d. As a result, the folded portion of each carcass cord has three or more intersections with other carcass cords.
[0009]
In this tire, each carcass cord is sufficiently adhered to the surrounding rubber at the folded portion thereof, and the folded portion intersects with many other carcass cords, for example, at the time of tire rolling. The stress acting on the carcass cord due to the bending deformation of the bead portion and the sidewall portion is sufficiently dispersed and supported by each of the other carcass cords. Since the relative restraining force is increased and the anchoring effect is improved, the carcass cord is effectively prevented from being damaged due to insufficient tensile strength, etc., and the distortion at the intersection of each carcass cord is effective. The durability of the bead portion can be effectively improved.
[0010]
More preferably, in this tire, at least one intersection is formed before and after each end of the folded portion of each carcass cord.
According to this, the intersections are arranged substantially evenly with respect to all the carcass cords, and the folded portion is overlapped with the adjacent folded portion almost evenly, so that the stress acting on the carcass cord is reduced in the entire tire circumferential direction. This also makes it possible to advantageously improve the durability of the bead portion by preventing a particularly large stress from acting on a specific carcass cord.
[0011]
And also, the production method of the present invention for such tires, particularly, each of the carcass cord of the plurality of number n by two pairs, the center distance D of the front and rear of the folded, all integral multiples of the plurality of number n 2n times the cord pitch d under the carcass cord arrangement state of the carcass cord, and the interval between the plurality of n-th carcass cords of the first pair in the circumferential direction of the tire is twice the cord pitch d. And the second pair of n + 1 and subsequent carcass cords are extended between the plurality of n pairs of carcass cords in the opposite direction and arranged at a cord pitch d. It is.
[0012]
In this method, for example, when the number n of the first pair is 5, and the number of all carcass cords is 10, which is 2 × n, each carcass cord intersects with nine carcass cords at the folded portion. In addition, the front tire can be easily and reliably realized by providing one or more intersections at the front and rear of each carcass cord at the edge of the folded portion.
[0013]
In this method, more preferably, the center distance D is 10 mm or more, thereby preventing plastic deformation of the folded portion of the carcass cord when the carcass cord is a steel cord, and making the bead portion easy. Secure.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a meridian cross-sectional view showing an embodiment of the present invention for a half portion of a tire, in which 1 is a tread portion and 2 is a pair of sidewalls extending radially inward continuously to the tread portion 1. The reference numeral 3 denotes a bead part that is continuous inward in the radial direction of each sidewall part 2, and 4 denotes a bead core embedded in the bead part 3.
[0015]
Here, in such a tire, a portion from the tread portion 1 through the sidewall portion 2 to the bead portion 3 is reinforced by a carcass 5 made of a carcass ply, and at least one carcass ply 6 of such a carcass 5 is connected to a pair of tires. The ply main body portion 7 is connected to the toroidal and straddles the bead portion 3, and the winding portion 8 is wound around the bead core 4 embedded in the bead portion 3 from the inside to the outside of the tire.
[0016]
Then, each of the plurality of carcass cords extending substantially in the tire meridian direction at the ply main body portion 7 is substantially the same at each winding portion 8 as shown in the partial development view of the carcass ply 6 in FIG. Folded in a U-shape to bend and extend in the circumferential direction of the tire, and the folded portion of each carcass cord 10 intersects other carcass cords 10 at three or more intersections in the drawing, nine in the figure, More preferably, at least one crossing portion is formed at the front and rear, with the edge e of the folded portion of each carcass cord 10 as a boundary, and 4 to 5 portions are formed in the figure. In other words, this means that the folded portions overlap almost uniformly over the entire circumference.
[0017]
FIG. 3 is a partial development view illustrating the carcass ply 6 having the minimum number of cords so as to facilitate understanding of these points. Four carcasses extending in a curved manner, that is, two pairs of carcass in pairs. Each of the cords 10 is folded back in a substantially U-shape and intersects with the other carcass cords 10 at three intersections 11, and each carcass cord 10 has an edge e of the folded portion as a boundary. In this case, one or two intersecting portions 11 are formed on the front and rear sides. According to this, the stress acting on each carcass cord 10 is distributed according to the number of the intersecting portions 11, and the carcass cord is combined. The anchor effect can be enhanced, and the entire stress can be sufficiently evenly distributed over the entire tire circumferential direction.
[0018]
By the way, in the structure as described above for at least one carcass ply 6, for example, as shown in FIG. 3, the center distance D before and after the folding of each of the plurality of carcass cords 10 in which the number n is two. The cord pitch d under the arrangement state of all the carcass cords 10 is set to 2n times, that is, four times, and the plurality of n carcass cords 10 of the first pair are arranged in the tire circumferential direction. Further, the second pair of n + 1 and subsequent carcass cords 10 in the figure, the third and subsequent carcass cords 10 are arranged between the pair of n carcass cords. If the code that reversed, so Zaisa plurality of rolling code pitch d can be realized by arranging, this increases depending plural number n to the required, As shown in FIG. 2 For example, versa when did the number n 5 present a.
[0019]
Here, when the carcass 5 is composed of a plurality of carcass plies, the carcass ply, that is, the carcass winding end of the carcass winding end is formed by adopting the above-described structure of the carcass ply in which at least the winding end is located at the outermost radial direction. , Separation from the surrounding rubber can be advantageously prevented.
[0020]
When the carcass cord 10 is disposed as described above, when the carcass cord is a steel cord, the center distance D described above is set to 10 mm or more, and the plasticity to the folded portion of the carcass cord 10 is set. It is preferable in manufacturing to sufficiently prevent the occurrence of deformation.
[0021]
Thus, in this tire, the adhesion of the carcass winding end to the surrounding rubber can be greatly improved based on the formation of the folded portion on the carcass cord 10, and the folded portion can be connected to other carcass cords 10. By having three or more intersections 11, stress acting on the carcass cords 10 can be sufficiently dispersed in the intersection cords and the anchor effect of the carcass cords themselves can be enhanced. In addition, the durability of the bead portion 3 can be greatly improved by effectively preventing damage to the cord itself and the like.
[0022]
The durability of the bead portion is such that the stress acting on each carcass cord 10 is sufficiently equal by forming one or more crossing portions before and after the edge e of the folded portion of each carcass cord 10. It will be further improved if it is conditioned.
[0023]
【Example】
Regarding the tire according to the present invention, the measurement results of the bead portion durability and the tire weight are as shown in Table 1.
Here, the example tire 1 has a size of 11R22.5, and each of the carcass and the carcass ply is configured by arranging one ply of steel cords in the order shown in FIG. 2, and the bead portion structure is shown in FIG. As shown in FIG. 1, the hexagonal bead is reinforced by a wire chafer, a nylon chafer and a rubber chafer, and the end of the wire chafer is set so as not to exceed the ply winding end, and between the wire chafer end and the ply winding end. A sufficient level difference is provided. In addition, the tire 2 of the example has a structure in which a hexagonal bead is reinforced only with a wire chafer from the viewpoint of further weight reduction.
The comparative tire is composed of a sheet cutting member in which a single carcass ply shown in FIG. 1 is coated with a rubber coating on a plurality of steel cords arranged in parallel in a straight line. The one carcass ply shown in FIG. 1 has an intermittent folding structure as shown in FIG.
[0024]
In addition, bead part durability was calculated | required by measuring the driving | running distance until a bead part failed on the conditions of load 5000kgf, internal pressure 900kPa, speed 60km / h, and carrying out index evaluation by making a comparative tire into control.
[0025]
[Table 1]

[0026]
Table 1 As is clear in Example from the tire 1, since it up for the carcass ply up end of separation can sufficiently removed by lowering the stiffener and side rubber volume of the winding portion near the tire than comparative tires The weight can be reduced effectively, and the carcass cord folding part has nine intersections with other carcass cords, greatly improving the durability of the bead part compared to both the comparative tire and the conventional tire. I was able to.
In particular, in the tire 2 of Example, the weight of the tire could be effectively reduced compared with the conventional tire by simplifying the reinforcement structure of the bead portion.
[0027]
【The invention's effect】
As is clear from the above examples, according to the present invention, the tire weight can be further reduced and the bead portion durability can be sufficiently improved.
[Brief description of the drawings]
FIG. 1 is a meridian sectional view showing an embodiment of the present invention with respect to a half portion of a tire.
FIG. 2 is a partial development view of a carcass ply.
FIG. 3 is a partial development view of a carcass ply having a minimum number of cords.
4 is a partial development view of a carcass ply of a conventional tire 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Carcass 6 Carcass ply 7 Ply main-body part 8 Winding part 10 Carcass cord 11 Crossing part n Arbitrary number D Center distance d Code pitch p Tire circumferential direction distance

Claims (4)

The carcass ply includes a carcass ply that reaches the bead part from the tread part through the sidewall part, and at least one carcass ply straddles the pair of bead parts and the ply main body part connected to the toroidal and the bead core around the bead core. A pneumatic tire composed of a wound-up part wound up,
Each of the plurality of carcass cords extending substantially in the tire meridian direction at the ply main body portion is folded at each winding portion so as to bend and extend in the tire circumferential direction, and two pairs of carcass each including a plurality of n pieces The center distance D of each cord before and after turning is set to 2n times the cord pitch d under the arrangement state of all the carcass cords. The second pair of n + 1 and subsequent carcass cords are arranged in the direction opposite to those cords between the pair of n carcass cords. A pneumatic tire having three or more intersections with the other carcass cords of the folded portion of each carcass cord by being arranged at a cord pitch d in the direction .   The pneumatic tire according to claim 1, wherein each carcass cord is formed with at least one intersecting portion with another carcass cord before and after the edge of the folded portion. When molding the pneumatic tire according to claim 1 or 2, the center distance D before and after the folding of each of a plurality of n pairs of carcass cords is determined under the arrangement state of all carcass cords. 2n times the cord pitch d of the first and second carcass cords of the first pair are arranged in the tire circumferential direction with an interval of twice the cord pitch d . A method of manufacturing a pneumatic tire, characterized in that n + 1 and subsequent carcass cords are arranged between the plurality of n carcass cords of the first pair in a direction opposite to the cords at a cord pitch d. .   The manufacturing method of the pneumatic tire of Claim 3 which made the said center distance D 10 mm or more.

Images