JPH04118308A - Pneumatic bias tire for heavy load - Google Patents

Abstract

PURPOSE:To prevent the separation between the outermost side carcass ply and a plain woven chafer and improve the durability of a bead part by successively arranging a reed screen type woven chafer and the plain woven chafer outside the bead part of the carcass ply arranged on the uppermost side. CONSTITUTION:Around the left and right bead cores 2a and 2b in pair, two carcass plies 1a, 1b and 1c, 1d are turned back, and two carcass plies 1'a and 1'b are wound down on the outside. In this case, a reed screen type woven chafer 4 is arranged outside the bead part of the outermost side carcass ply 1'b, and a plain woven chafer 3 is arranged outside the reed screen type woven chafer 4. As for the reed screen type woven chafer 4, the height h2 from the rim base at the upper edge of the reed screen type woven chafer 4 is set to the height in 110% or more of the rim flange height RH of a used rim R. While, as for the plain woven chafer 3, the height h1 from the rim base is set lower than the height h2 from the rim base at the upper edge of the reed screen type woven chafer 4, and a step difference is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heavy-duty pneumatic bias tire with improved bead durability.

[Prior art]

In a pneumatic bias tire for heavy loads (hereinafter referred to as a bias tire for heavy loads), rim displacement and rim cuts are likely to occur in the bead region in contact with the rim flange. Therefore, as a measure to improve the durability of the bead portion, a plain weave chafer has been placed outside the outermost carcass ply in the bead portion. In this bead reinforcement structure, as will be described later, due to the structure of the plain weave chafer, peeling between the outermost carcass ply and the plain weave chafer is unavoidable. A rubber strip was interposed between them.

To explain this with the drawings, as shown in FIG. 4 as an example of the bead structure, two pairs of bead cores 2a and 2b are provided, and two carcass plies 1 are arranged around each bead core 2a and 2b. a +1b and lc,
ld is folded back from the inside of the tire to the outside, and two carcass plies l' a + 1 are placed on the outside of the ld.
' b has been rolled down from the outside of the tire to near the bead base. A plain weave chafer 3 is arranged outside this outermost carcass ply l'b. However, in this plain weave chafer 3, the coated rubber is surrounded by a diamond-shaped space made of warp and weft threads, which inhibits the adhesion with the rubber of the outermost carcass ply due to the pantograph effect that occurs when the tire rotates. Therefore, in order to prevent this, a rubber strip 5 is interposed in the upper end area of the rim flange to prevent separation.

However, although the separation resistance effect was achieved to some extent by interposing the rubber strip, it was still not sufficient.

[Problem to be solved by the invention]

An object of the present invention is to provide a heavy-duty bias tire that prevents separation between the outermost carcass ply and the plain weave chafer and improves the durability of the bead portion.

[Means for Solving the Problems] An object of the present invention is to create a bias fabric in which carcass plies consisting of a plurality of organic fiber cords are laminated so that the cord directions cross each other, and both ends are folded back around a bead core. In a pneumatic tire of this structure, at least one woven chafer made of organic fiber cords having a cord angle of 45° to 75° with respect to the tire circumferential direction is arranged outside the bead portion of the outermost carcass ply. A plain weave chafer made of organic fiber cords is disposed outside the blind weave chafer, and
The upper end of the innermost woven chafer is set to a height of 110% or more of the height of the rim flange used, and the upper end of the plain woven chafer is set at a step-like position lower than the upper end of the N-woven chafer. This can be achieved by

In this way, instead of placing the hand-woven chafer directly outside the bead of the carcass ply cord placed on the outermost side, we placed a blind-woven chafer with a fixed cord angle to sandwich it, unlike the conventional method. Without using a rubber strip, it is possible to prevent separation due to the pantograph effect of the plain weave chafer that occurs during tire rotation, and to obtain the effect of preventing rim displacement and rim cut caused by the plain weave chafer. In addition, use the upper end of the innermost blind weave chafer.
10% or more, and the upper end of the hand-woven chafer is set lower than the upper end of the blind-woven chafer in a step-like manner, thereby alleviating the concentration of stress on the ends of the plurality of chafers and improving the separation. can be prevented.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing an example of the bead structure of the tire of the present invention, and FIG. 2 is a perspective view showing the tire with the rubber layer removed from its outer surface. In these figures, two pairs of left and right bead cores 2a, 2b: 2a, 2b are surrounded by two carcass plies la, lb, lc, l.
d is folded back from the inside of the tire toward the outside, and on the outside thereof, two carcass plies 1'a+1'b are wound down from the outside of the tire to near the bead base portion. A blind weave chafer 4 is arranged outside the bead portion of the outermost carcass ply I'b, and a plain weave chafer 3 is further arranged outside of this blind weave chafer 4.

The N-woven chafer 4 is arranged to be inclined at a cord angle θ with respect to the tire circumferential direction E, and its lower end extends to a position near the bead heel 6, and its upper end has a height h2 from the rim base of the rim R used. It is arranged at a height of 11 oz or more of the flange height RH. Further, on the outside of this blind weave chafer 4, a plain weave chafer 3 is arranged which is folded back outward so as to cover the bead base from the inside of the bead portion. This plain weave chafer 3 is arranged in a stepped position in which the height hl of the upper end from the rim base is lower than the height h2 of the upper end of the blind weave chafer 4 from the rim base.

FIG. 3 is a sectional view showing another example of the heat section structure of the tire of the present invention. In this example, in the bead part configuration in the case of FIG. 1, two blind weave chafers 4, 4' are arranged outside the bead part of the outermost carcass ply l'b. The first (inside) blind weave chafer 4 has its lower end placed near the middle of the rim flange, and the upper end has a height h2 from the rim base that is 110% or more of the flange height RH of the rim R. .

On the other hand, the second (outside) blind weave chafer 4゛ is
The lower end thereof is arranged so as to extend to the vicinity of the bead heel 6, and covers the lower end of the first blind weave chafer 4. Further, the height h3 of the upper end from the rim base is lower than the height h2 of the upper end of the first blind weave chafer 4 from the rim base, so that it has a stepped shape.

Furthermore, plain weave chafer 3 is the second blind weave chafer.
It is folded back from the inside of the tire to the outside around the bead portion at an angle of 4°, and covers the lower end of the second blind weave chafer 4°. The height of the upper end of this plain weave chafer 3 from the rim base is lower than the height h3 of the upper end of the second blind weave chafer 4'' from the rim base,
It is stepped. In addition, when using multiple blind weave chafers as in this example,
It is desirable to arrange the cords so that they cross each other.

In each of the above-mentioned embodiments, the cord angle θ of the blind weave chafer directly adjacent to the outermost carcass ply is 45° to 75″ with respect to the tire circumferential direction, preferably 50° to 70°.
Place them in a range of 6. If this cord angle θ falls outside the above range, the cord angle difference between the bias structure and the outermost carcass ply will increase, and the distortion between the outermost carcass ply and the S-weave chafer outside its bead portion will increase. Ply separation occurs and the durability of the bead portion decreases. Furthermore, the cord direction of the blind weave chafer directly adjacent to the outermost carcass ply may be intersecting or parallel to the cords of the outermost carcass ply, but it is preferable that they intersect.

In the tire of the present invention, the innermost woven chafer among the woven chafers arranged outside the bead portion of the outermost carcass ply has a height from the rim base of its upper end to 110% or more of the rim flange height RH. I will make it happen.

If the height of this upper end becomes less than 110χ of the rim flange height RH, it becomes difficult to reduce rim displacement and rim cut, and the bead portion durability cannot be sufficiently improved.

Furthermore, for the plain weave chafer placed outside this blind weave chafer, and for the second and subsequent chafers when two or more chafers are placed, the upper end of the chafer on the outside is Arrange it in a stepped manner at a position lower than the upper end of the chafer. In this way, by arranging the upper end of the plain weave chafer in a step-like manner at a low position, stress concentration on the end is alleviated,
Separation can be prevented. Preferably, the height of each shift in the lower direction is 5 to 5.
The range is preferably 20 mm.

The organic fiber cords constituting the blind weave chafer and plain weave chafer of the tire of the present invention are not particularly limited, and various known fiber cords such as nylon cords and polyester fiber cords (840D/2.1260D/2) can be used. can be used.

〔Example〕

Example 1 As shown in Table 1, the bead structure, the type and number of chafers, the presence or absence of rubber strips, and the chafers
Four types of tires 1 to 3 of the present invention and a conventional tire were manufactured in which the cord direction with respect to the outermost carcass ply cord was changed.

All these tire sizes are the same 100020
It was set as 14PR.

In tires 1 to 3 of the present invention, the cord angle θ of the waist edge chafer directly adjacent to the outermost carcass ply was set to 60' with respect to the tire circumferential direction. Further, the two curtain weave chafers used in the tire 2 of the present invention were arranged so that the cords crossed each other.

The bead durability of these tires was evaluated by the following method. The results are shown in Table 1.

Bead part i method: A tire whose crown tresode has been ground down to almost complete wear is mounted on a rim with a rim size of 20 x 7.50V, and JISo
After completing the durability performance test described in ``4230r Automotive Tires'', the load index was increased to 172 at a constant speed every 8 hours.
Evaluation was made by displaying the distance at which a failure occurred in the bead section as an index when the vehicle was run with the vehicle increasing in increments.

The index is shown based on the measured value of a conventional tire (100). The larger the index value, the better the bead durability.

In the upper table of Table 1, Cap: This is the cord direction of the waist edge chafer with respect to the cord direction of the outermost carcass ply.

From Table 1, the bead portion durability of the tire 3 of the present invention is improved compared to the conventional tire. Furthermore, when the cords of the outermost carcass ply and the innermost waist edge chafer directly adjacent thereto intersect as in the tire 1 of the present invention, the durability of the bead portion is improved. Furthermore, as in the tire 2 of the present invention, by increasing the number of waist edge chafers, the durability of the bead portion can be significantly improved.

Example 2 Five types of tires 4 to 5 of the present invention were prepared in which the cord angle θ of the waist edge chafer with respect to the tire circumferential direction was changed as shown in Table 2 in the tire having the bead structure shown in FIG.
Comparative tires 1 to 3 were manufactured. The bead durability of these tires was evaluated and expressed as an index based on the measured value of the conventional tire described above (100). The results are shown in Table 2.

The tire 1 of the present invention is the same as the tire 1 of the present invention in Example 1.

(Margins below this page) Table 2 From Table 2, when the cord angle θ of the waist edge chafer with respect to the tire circumferential direction is set in the range of 45° to 75°,
It can be seen that the bead durability is improved compared to conventional tires.

〔Effect of the invention〕

According to the present invention, in a pneumatic tire in which the carcass ply has a bias structure, a waist edge chafer made of an organic fiber cord having a cord angle of 45° to 756° with respect to the tire circumferential direction is provided on the outside of the bead portion of the outermost carcass ply. At least one sheet of - is arranged, and a plain weave chafer made of an organic fiber coat is arranged on the outside of the waist edge chafer, thereby preventing separation of the plain weave chafer, resulting in excellent rim slip resistance of the plain weave chafer. It is also possible to exhibit rim cut resistance and improve bead part durability. In addition, by making the upper end of the innermost waist edge chafer higher than 110% of the height of the used rim flange, and arranging the upper end of the plain weave chafer at a lower position in a stepped manner, multiple chafers can be stacked. Stress concentration on the end of the bead portion can be alleviated and separation can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one example of the bead structure of the tire of the present invention, FIG. 2 is a perspective view of FIG. 1, and FIG. 3 is a cross-sectional view showing another example of the bead structure of the tire of the present invention. FIG. 4 is a sectional view showing the bead structure of a conventional tire. 1a+ lb, 1c+ 1d, Par l'b
... Carcass ply, 2a, 2b... Bead core, 3... Plain weave chafer - 4.4'... Waist edge chafer, R... Rim, RH... Rim flange height.

Claims (1)

[Claims] In a pneumatic tire with a bias structure in which carcass plies consisting of multiple organic fiber cords are stacked so that the cord directions cross each other and both ends are folded back around a bead core, the outside of the bead of the outermost carcass ply , the cord angle with respect to the tire circumferential direction is 45° to 7
Arranging at least one or more blind weave chafer made of 5° organic fiber cord, and arranging a plain weave chafer made of organic fiber cord on the outside of the blind weave chafer,
And the upper end of the innermost blind weave chafer among the said blind weave chafers is set to a height of 110% or more of the height of the used rim flange, and the upper end of the plain weave chafer is set to have a step higher than the upper end of the said blind weave chafer. A pneumatic bias tire for heavy loads with a low position.