JPH0624215A - Heavy duty pneumatic bias tire - Google Patents

Abstract

PURPOSE:To prevent separation from the carcass ply end and cord severance in the part where carcass ply is folded back by giving a value 0.3mm to a rubber gauge on at least one surface of each carcass ply in the region specifically determined from the bead base, and not allowing the carcass ply end to lie there. CONSTITUTION:In the folded-back part of each carcass ply 18 wound on a bead core 16 situated outside in the tire axial direction, rubber gauge between carcass plies is made over 0.3mm in the region 0.9-1.5H from the bead base 12B on which a large compressive force acts at the time of over-load, where H represents the height of a rim flange 29, and also no carcass ply end 24B, 25B, 26B is allowed to lie there. This achieves preventing separation from the ends 24B, 25B, 26B and cord severance in the part where carcass ply 18 is folded back.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty pneumatic bias tire, and more particularly to a heavy-duty pneumatic bias tire having a plurality of axially spaced bead cores, and a plurality of carcass plies wound up from the inside to the outside of each bead core. The present invention relates to a heavy duty pneumatic bias tire.

[0002]

2. Description of the Related Art A heavy duty pneumatic bias tire mounted on a truck or the like has a plurality of bead cores axially separated from each other because strength is required, and a plurality of carcass plies are provided on each bead core from inside to outside of the tire. Has been wound up.

In recent years, tire specifications have changed significantly in order to reduce fuel consumption and improve productivity by reducing tire weight. For example, the cord diameter used for carcass plies ranges from 840 denier / 2 to 1260 denier / 2
, And further changed to 1890 denier / 2 to improve the cord strength, and the cord diameter from φ0.51 to φ0.61,
Furthermore, it is changing to φ0.76 thickly. As described above, by increasing the diameter of the cord used for the carcass ply to improve the strength, the number of plies can be reduced, the weight is reduced, and the productivity is improved.

[0004]

By the way, under a situation in which the load capacity of a tire is far exceeded, for example, when the specified load is 1
When the tire is used at 50% or more, the tire is largely deformed, and a large compressive force acts from the bead portion to the inside of the tire side portion and the outside of the upper portion of the rim flange abutting portion immediately below the load.

Although there are many carcass plies in the actual number and no problem has occurred in the conventional pneumatic bias tire for heavy load using a fine denier cord, the cord diameter is increased in order to reduce the number of carcass plies. As the strength is increased, problems such as separation occurring from the ply end and breaking of the cord in the carcass ply begin to appear.In particular, the separation is the carcass ply turnup part that winds up the outermost bead core of the tire. Of the carcass ply that winds up the bead core on the outermost side of the tire.

For this failure, measures are taken such as covering 20 to 30 mm from the ply end to the bead core side with a rubber sheet, or thickening the rubber gauge around the ply end from the ply end to the bead core side to 20 to 30 mm. However, the effect of preventing the occurrence of separation was recognized to some extent, but it was not sufficient, and there was no effect in preventing the cord breakage. Further, the method of covering 20 to 30 mm from the end of the ply with a rubber sheet has a drawback that workability is remarkably reduced and the manufacturing cost is increased.

In consideration of the above facts, the present invention provides a heavy-duty pneumatic bias tire that is light in weight and can prevent separation from the end of the carcass ply and breakage of the cord at the folded back portion of the carcass ply. Is the purpose.

[0008]

DISCLOSURE OF THE INVENTION As a result of investigating a tire having a failure and performing an overload test on the tire, the inventors found that a cord breakage occurs when the cord is subjected to a compressive force. It was discovered that cracks called kink bands occur in filaments that compose cords, which occur in many filaments, which results in breakage of the cords. From this, the inventor studied variously and widened the distance between the cords. Specifically, if the rubber was added between the plies to widen the distance, the cords could be slightly bent when a compressive force was applied. It has been discovered that this can reduce the compressive force acting on the filament and delay the formation of kink bands.

Further, as a result of predicting a dangerous area (fault occurrence area) by FEM calculation and performing a performance test with a test tire, the inventor has provided a plurality of carcass plies made of organic fiber cords and provided each bead portion. In a heavy-duty pneumatic bias tire in which a plurality of bead cores are spaced apart from each other in the axial direction of the tire, and a plurality of carcass plies are wound around each bead core from the tire inside to the outside, the position of the carcass ply end and the rim flange height are In the folded portion of the carcass ply rolled up on the outermost bead core in the axial direction of the tire in an overloaded state, 0.9H to 1.5H from the bead base
A large compressive force acts in the region of (rim flange height H), and at the folded portion of the carcass ply wound up on the bead core on the inner side in the tire axial direction, 1.5 from the bead base.
It is found that a large compressive force acts in the region of H to 2.5H, and the rubber gauge of the carcass ply at the folded portion of the carcass ply wound around the outermost bead core in the tire axial direction is usually about 0.2 mm. However, the rubber gauge of the carcass ply in the folded portion of the carcass ply wound around the bead core on the inner side in the tire axial direction is set to 0.3 mm or more on at least one side in the region of 0.9H to 1.5H from the bead base,
Normally, it is about 0.2 mm, but at least 1.5 mm to 2.5 H from the bead base, 0.3 at least on one side.
We have found that setting it to mm or more is effective in preventing cord breakage.

The present invention has been made as a result of various studies in view of the above-mentioned problems. The invention according to claim 1 is
A plurality of carcass plies made of organic fiber cords are provided in a laminated manner and a plurality of bead cores are provided at each bead portion so as to be separated from each other in the tire axial direction, and a plurality of carcass plies are wound on each bead core from the tire inner side to the outer side. In the heavy-duty pneumatic bias tire, when the rim flange height is set to H, the folded portion of the carcass ply rolled up on the outermost bead core in the tire axial direction is in a region of 0.9H to 1.5H from the bead base. It is characterized in that the rubber gauge on at least one side of each carcass ply is 0.3 mm or more and the end of the carcass ply is not positioned.

According to a second aspect of the present invention, in the heavy-duty pneumatic bias tire according to the first aspect, the folded portion of the carcass ply wound around the bead core on the inner side in the axial direction of the tire is 1.5H to 1.5H from the bead base.
In the area of 2.5H, the rubber gauge on at least one side of each carcass ply is 0.3 mm or more, and the end of the carcass ply is not positioned.

[0012]

According to the pneumatic bias tire for heavy loads according to the first aspect of the present invention, the folded portion of the carcass ply wound up on the outermost bead core in the axial direction of the tire has a bead base which causes an extremely large compression strain when the tire is overloaded. The carcass ply end is not positioned in the region of .9H to 1.5H, and since the rubber gauge on at least one side of the carcass ply is 0.3 mm or more in this region, a large stress acts on the end of the carcass ply. In addition, since the cord can be slightly bent, the compressive force acting on the filament is relaxed. Therefore, it is possible to prevent the occurrence of separation caused by the carcass ply end as a core and the occurrence of cord breakage at the folded portion of the carcass ply.

The end of the carcass ply may be set to a position less than 0.9H or more than 1.5H from the bead base. In practice, however, the carcass ply end is moved from the position of 0.9H to the bead base side. It is not preferable to be more than 20mm away, and 100 from the position of 1.5H to the tire side.
It is not preferable to be more than mm. That is, from the position where the carcass ply end is 0.9H to the bead base side, 20mm
If it is separated from the above distance, the bead rigidity is reduced, the movement of the bead is increased, and a problem such as rim displacement may be induced. On the other hand, when the end of the carcass ply is separated from the position of 1.5H toward the tire side by 100 mm or more, the workability at the time of tire assembly is reduced, the weight is increased, and the cost is increased, which is not preferable.

Further, with respect to the folded-back portion of the carcass ply wound around the outermost bead core in the tire axial direction,
If the rubber gauge between the carcass plies is less than 0.3 mm, the effect of preventing cord breakage is small. On the other hand, if the rubber gauge between the carcass plies is about 2 mm or more, it is preferable only for the purpose of reducing the compressive force acting on the filament, but the tire temperature rises due to the increase in the rubber capacity, so the various properties of the rubber deteriorate. As a result, separation easily occurs and the tire weight increases, which is not preferable. Therefore, taking these into consideration, the rubber gauge between the plies is 0.3 to 1.5 mm in the practical range and 0.3 to 1.0 mm in the desirable range.

According to the second aspect of the present invention, in the heavy-duty pneumatic bias tire according to the first aspect, the carcass ply wound up around the bead core on the inner side in the axial direction of the tire in which extremely large compression strain is generated when the tire is overloaded is folded back. About the part, 1.5H to 2.5H from the bead base
In the area of, since the rubber gauge on at least one side of the carcass ply is 0.3 mm or more, a large stress does not act on the end of the carcass ply, and the cord can be slightly bent, so that the compressive force acting on the filament is reduced. Will be alleviated. Therefore, it is possible to prevent the occurrence of separation caused by the carcass ply end as a core and the occurrence of cord breakage at the folded portion of the carcass ply.

The carcass ply end may be set to a position less than 1.5H or more than 2.5H from the bead base. In practice, however, the carcass ply end is moved from the position of 1.5H to the bead base side. It is not preferable to be more than 50mm away from the 2.5H position to the tire side 50mm
It is not preferable to separate from the above. That is, when the end of the carcass ply is separated from the position of 1.5H to the bead base side by 50 mm or more, the bead rigidity is reduced, the movement of the bead is increased, and a problem such as rim displacement may be induced. On the other hand, if the end of the carcass ply is separated from the position of 2.5H toward the tire side by 50 mm or more, the workability at the time of tire assembly is decreased, the weight is increased, and the cost is increased, which is not preferable.

Further, regarding the folded-back portion of the carcass ply wound up on the innermost bead core in the axial direction of the tire,
If the rubber gauge between the carcass plies is less than 0.3 mm, the effect of preventing cord breakage is small. On the other hand, if the rubber gauge between the carcass plies is about 2 mm or more, it is preferable only for the purpose of reducing the compressive force acting on the filament, but the tire temperature rises due to the increase in the rubber capacity, so the various properties of the rubber deteriorate. As a result, separation easily occurs and the tire weight increases, which is not preferable. Therefore, taking these into consideration, the rubber gauge between the plies is 0.3 to 1.5 mm in the practical range and 0.3 to 1.0 mm in the desirable range.

[0018]

【Example】

[First Embodiment] A first embodiment of a heavy duty pneumatic bias tire according to the present invention will be described with reference to FIGS.

The heavy duty pneumatic bias tire 10 of this embodiment has a size of TBS 12.00-24 16P.
As shown in FIG. 1, the bead portion 12 is provided with two bundles of bead cores 14 and 16 arranged side by side in the tire axial direction (the arrow A direction and the direction opposite to the arrow A direction).

Inside of tire (direction opposite to arrow A)
In the bead core 14 of No. 3, the carcass ply 18 made of an organic fiber cord (nylon cord 1890d / 2 in this embodiment, not shown in FIG. 1) is provided from the inside of the tire to the outside (the direction of the arrow A). The bead core 16 on the outer side of the tire has three carcass plies 18 made of organic fiber cord wound from the inner side to the outer side of the tire. Further, a carcass ply 18 made of an organic fiber cord that does not wind up the bead cores 14, 16 is provided on the outer side of the tire of the carcass ply 18 having the bead cores 16 wound up on the outer side of the tire.
One is provided. In addition, these carcass ply 18
Hereinafter, the first ply 21, the second ply 22 ... The eighth ply 28 will be referred to in order from the inside of the tire.

In the adjacent carcass ply 18, the organic fiber cords are arranged so as to intersect with each other. In this embodiment, the angle of the organic fiber cords with respect to the tire equatorial plane is set to 40 °.

In the heavy duty pneumatic bias tire 10 of this embodiment, when the height of the rim flange 29 is H (44.5 mm in this embodiment), the ply end 21B of the first ply 21 is the bead base 12B. From the tire radial direction outward (arrow B direction) to about 3.13H, the ply end 22B of the second ply 22 is about 2.67H from the bead base 12B, and the ply end 23B of the third ply 23 is about 1 from the bead base 12B. It is arranged at a position of 0.44H.

On the other hand, the ply end 24B of the fourth ply 24 is about 3.18H from the bead base 12B, and the fifth ply 25 is
The ply end 25B is about 2.56 from the bead base 12B.
H, the ply end 26B of the sixth ply 26 is the bead base 1
It is arranged at a position of about 1.87H from 2B.

Fourth ply 24, fifth ply 25 and sixth ply
A rubber sheet 30 (indicated by a broken line) having a predetermined thickness is provided on the tire axially outer side of each folded-back portion 24A, 25A, 26A of the ply 26.
4, the interval between the organic fiber cord 31 of the fifth ply 25 and the sixth ply 26 and the organic fiber cord 31 of the ply adjacent to the tire axial direction outer side (see FIG. 2), that is, each folded portion 24A, The rubber gauge T on the outer side in the tire axial direction of 25A and 26A is set to 0.3 mm.

The folded-back portion 24A of the fourth ply 24
The area where the rubber gauge is secured at 0.3 mm on the outer side in the tire axial direction is from the ply end 24B of the fourth ply 24 to the bead core 16 side up to 120 mm.
The region where the rubber gauge of 0.3 mm is secured outside the folded-back portion 25A of the ply 25 in the tire axial direction is the fifth region.
9 from the ply end 25B of the ply 25 to the bead core 16 side
It is a range up to 0 mm, and the folded-back portion 2 of the sixth ply 26 is
The rubber gauge is 0.3 mm on the outside of the 6A tire in the axial direction.
The secured area is the ply end 26 of the sixth ply 26.
The range from B to the bead core 16 side is 60 mm.

The ply end 27B of the seventh ply 27 and the ply end 28B of the eighth ply 28 are bead toe 12A.
It is located in the vicinity.

Next, the operation of this embodiment will be described. In the heavy duty pneumatic bias tire 10 according to the present embodiment, the carcass ply 1 wound around the bead core 16 on the outer side of the tire.
The carcass ply ends 24A, 25A, 26A are not located in the region of 0.9H to 1.5H from the bead base 12B in which the extremely large compression strain occurs when the tires are overloaded for the folding portions 24A, 25A, 26A of 8. Therefore, the occurrence of separation caused by the carcass ply ends 24B, 25B, and 26B as cores is prevented. further,
In the region of 0.9H to 1.5H from the bead base 12B, since the rubber gauge on the tire outer side of the folded-back portions 24A, 25A and 26A is 0.3 mm or more, the organic fiber cord can be slightly bent, and the organic fiber cord can be bent. The compressive force acting on the filaments of the is relaxed. For this reason, the breakage of the cords in the folded portions 24A, 25A and 26A is prevented.

The folded portions 21A, 2A of the carcass ply 18 wound around the bead core 14 inside the tire
For 2A and 23A, 1.5H from the bead base 12B that causes extremely large compression strain when the tire is overloaded.
In the area of 2.5H, the carcass ply ends 21B, 22
Since B and 23B are not located, the occurrence of separation caused by the carcass ply ends 21B, 22B and 23B as cores is prevented.

Second Embodiment] A second embodiment of the heavy duty pneumatic bias tire according to the present invention will be described.

The heavy duty pneumatic bias tire 10 of this embodiment has the same size as the heavy duty pneumatic bias tire 10 of the first embodiment, and is different from the heavy duty pneumatic bias tire 10 of the first embodiment. The dimensions of the rubber gauge on the outer side in the tire axial direction of the folded portion. Other configurations are similar to those of the heavy duty pneumatic bias tire 10 of the first embodiment.

In the heavy duty pneumatic bias tire 10 of this embodiment, a rubber sheet 30 (not shown) having a predetermined thickness is provided on the tire axially outer side of the folded-back portions 21A and 22A of the first ply 21 and the second ply 22. Is disposed, and the gap between the ply and the organic fiber cord 31 adjacent to the tire axial direction outer side, that is, the folded portions 21A and 22.
The rubber gauge T on the outer side in the tire axial direction of A is set to 0.3 mm.

The folded-back portion 21A of the first ply 21
The area where the rubber gauge is secured at 0.3 mm on the outer side in the tire axial direction is from the ply end 21B of the first ply 21 to 100 mm toward the bead core 14 side.
The region where the rubber gauge of 0.3 mm is secured outside the folded-back portion 22A of the ply 22 in the tire axial direction is the second area.
7 from the ply end 22B of the ply 22 to the bead core 14 side
The range is up to 0 mm.

[Third Embodiment] The heavy load pneumatic bias tire 10 of the third embodiment has the same size as the heavy load pneumatic bias tire 10 of the first embodiment. The heavy load pneumatic bias tire 10 of the present embodiment is 0.3 mm in the heavy load pneumatic bias tire 10 of the second embodiment.
The only difference is that the secured rubber gauge has been changed to 1.0 mm. Other configurations and dimensions are similar to those of the second embodiment.

Test Example Table 1 below shows the results of testing the tire durability of three tires of the present invention and one conventional tire.

The tire durability is expressed as an index with the conventional tire being 100, with the tire durability being good when the running distance until the carcass ply breaks the cord is long. The larger the numerical value, the better. The endurance test is performed with an indoor drum tester, and the test conditions at this time are an internal pressure of 3.0 kg / cm ² and a load of 20% of the specified load.
The 0% load and the speed were set to 30 km / h, and the traveling distance until the cord was broken was measured.

The invention tire 1 in Table 1 is the heavy duty pneumatic bias tire of the first embodiment, and the invention tire 2 is the heavy duty pneumatic bias tire of the second embodiment. The tire 3 is the heavy duty pneumatic bias tire of the third embodiment.

The conventional tire is the tire shown in FIG. 3 and has the same size as the heavy duty pneumatic bias tire 10 of the first embodiment. In the conventional tire, the ply end 21B of the first ply 21 is about 2.
33H, the ply end 22B of the second ply 22 is arranged at a position of about 1.78H from the bead base 12B, and the ply end 23B of the third ply 23 is arranged at a position of about 1.11H from the bead base 12B. On the other hand, the ply end 24 of the fourth ply 24
B is about 2.71H from the bead base 12B, and the ply end 25B of the fifth ply 25 is about 2.71H from the bead base 12B.
02H, the ply end 26B of the sixth ply 23 is arranged at a position of about 1.40H from the bead base 12B. Further, the rubber sheet 30 is not provided between the plies, and the rubber gauge between the plies is about 0.2 mm.

[0038]

[Table 1]

From the test results in Table 1 above, the present inventions 1 to 3
It is clear that the heavy-duty pneumatic bias tire has improved tire durability as compared with the conventional tire.

[0040]

As described above, the heavy-duty pneumatic bias tire of the present invention can reduce the weight and prevent the separation from the end of the carcass ply and the breakage of the cord at the folded back portion of the carcass ply. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the vicinity of a bead portion of a heavy duty pneumatic bias tire according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of a carcass explaining a space between cords.

FIG. 3 is a cross-sectional view showing the vicinity of a bead portion of a conventional heavy duty pneumatic bias tire.

[Explanation of symbols]

 10 Pneumatic bias tire for heavy load 12 Bead part 14 Bead core 16 Bead core 18 Carcass ply 21A Folding part 22A Folding part 23A Folding part 24A Folding part 25A Folding part 26A Folding part 21B Ply end (Carcass ply end) 22B Ply end (Carcass ply end) ) 23B ply end (carcass ply end) 24B ply end (carcass ply end) 25B ply end (carcass ply end) 26B ply end (carcass ply end) 27B ply end (carcass ply end) 28B ply end (carcass ply end) 29 Rim flange

Claims (2)

[Claims] 1. A plurality of carcass plies made of organic fiber cords are provided in a laminated manner, and a plurality of bead cores are provided at each bead portion so as to be spaced apart from each other in the tire axial direction. In the heavy-duty pneumatic bias tire wound up on each of the above, when the rim flange height is set to H, the folded portion of the carcass ply wound up on the outermost bead core in the tire axial direction is 0.9H to 1H from the bead base. .5H
In the region (2), the pneumatic bias tire for heavy load is characterized in that at least one side of each carcass ply has a rubber gauge of 0.3 mm or more and the end of the carcass ply is not positioned. 2. With respect to the folded portion of the carcass ply wound up on the bead core on the inner side in the tire axial direction, the rubber gauge on at least one side of each carcass ply is 0.3 mm or more in the region of 1.5H to 2.5H from the bead base. The heavy-duty pneumatic bias tire according to claim 1, wherein the carcass ply end is not positioned.