JPS59118510A - Radial tyre - Google Patents

Abstract

PURPOSE:To improve the durability of the bead part of a tyre by winding up both ends of a carcass ply around bead cores and folding back each of the upper ends of the wound-up parts, thereby attenuating separation of rubber caused by concentration of stress at the upper ends of the folded-back parts. CONSTITUTION:A carcass ply 11, that is, a ply of metal cord coated with rubber is wound up at both ends around bead cores 12 and folded back at the upper ends thereof, and a rubber stock is disposed between the case's main body part 11a and the wound-up part 11b. A metal cord reinforcing ply 14 which surrounds the wound-up part 11 and extends from the outside towards the inside of the bead part via the bottom part thereof is disposed on the external side of the wound-up part 11b. The height (c) measured from the bead base part at the inside upper part shall exceed the height (b) measured from the bead base part of the upper end of the wounded-up part. The separation of rubber caused by concentration of stress at the upper end of the folded-back part 11c may be attenuated, thereby improving the durability of the bead part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of the heating section of a tire with a radial or semi-milano alkali carcass.

Generally, the heat section of a radial tire, especially a radial tire for heavy vehicles, is a heat core (3) as shown in Figure 1.
In order to reinforce the vicinity of the upper end (2a) of the carcass ply (21), which is rolled up from the inside to the outside, a reinforcing layer extends inward from the outside of the tire bead part through the bottom so as to surround this part. (4) is arranged. The reinforcing layer is for fixing the rolled up part of the carcass ply to the bead core and to relieve stress concentration in the rolled up part. Therefore, the outer upper end (4a) is usually the upper end of the rolled up part (4). However, in such a conventional structure, a new stress concentration occurs at the outer upper end (4a) of the reinforcing layer, and in order to avoid this, the outer upper end (4a) is covered with a hard rubber strip, A method of arranging a covering layer (5) such as a short fiber coat layer or an organic fiber cord layer, or a method of arranging a fiber cord layer (6) adjacent to the outside of the reinforcing layer (4) as shown in FIG. However, the mechanism of bly peeling at the outer upper end (4a) of the reinforcing layer (4) or the upper end (21) of the rolled-up portion is that the compressive strain near the end of the ply cord is applied in the direction in which the cord is arranged. This causes stress concentration due to the so-called "sticking phenomenon" in which the cut end of the ply cord, that is, the outer upper end (4n) of the reinforcing layer, bites into the surrounding rubber.
This, combined with the absence of an adhesive layer at the upper end (4a), causes ply delamination in that area. The present invention solves the above-mentioned problems, and proposes a radial tire in which the upper end of the rolled-up portion of the carcass ply is folded back to prevent brazier peeling due to the "sticking phenomenon" and to significantly improve heat durability. It is.

The present invention is constructed by winding both ends of at least one carcass ply made of a comb layer of radial or semi-radial arranged cords around a heat core, and folding back the upper end of the wound part, and forming a carcass ply formed by this carcass. A Comstock is disposed between the main body of the case and the winding part, and extends in the tire radial direction from the bottom adjacent to the heat core, and further extends inward from the outside of the heat part through the bottom so as to surround the winding part of the carcass. , a radial tire characterized in that a reinforcing layer is disposed whose outer upper end does not exceed the upper end of the rolled-up portion.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows the cross-sectional structure of the bead portion of the radial tire of the present invention. In the figure, a carcass ply (11) consisting of a rubberized layer of metal cord has both ends connected to a bead core (12).
), and its upper end is folded back, and a rubber stock is disposed between the case main body (11a) and the rolled-up part (llb). and a metal cord reinforcing layer (I4) is disposed on the outer side of the winding part (llb), surrounding the outside of the winding part and extending from the outside of the heat part through the bottom part to the inside;
The height 01 of the upper end of the inner side from the heat base part is arranged so as to exceed the height fbl of the upper end of the winding part from the heat base part.

Since the present invention has a structure in which the upper end of the winding part (UB) is folded back, the upper end is buried and fixed in the surrounding comb, and the sticking phenomenon is alleviated, and the upper end where this phenomenon is particularly severe is covered with an adhesive layer. As a result, rubber peeling is greatly reduced. The upper end of the reinforcing layer (14) is arranged so that it does not normally overlap with the upper end of the rolled-up part (Ilb), that is, the folded part (llc), but even if it overlaps, it must at least exceed the height of the rolled-up part (11b). must not. This is because if the upper end of the reinforcing layer, that is, the cut end, is located beyond the height bl of the rolled-up portion (11b), the rubber will peel off at that portion due to the sticking phenomenon as described above. Further, in the present invention, the height c) of the inner upper end of the heating part of the reinforcing layer (14) is set to the height bl of the rolled-up part (ub).
It is desirable to make it higher than that. This is because the folded part (lla) becomes extremely stiff and becomes the starting point of stress concentration due to the new stiffness level difference between it and the surrounding rubber. The rigidity of the main body of the case, that is, the inside of the heat section, is lower than that of the outside, and interlayer shear strain in the heat section is likely to occur. Therefore, in the present invention, by arranging the inner upper end of the reinforcing layer (14) higher than the upper end of the winding part, the main body part of the case (on)
This strengthens the structure and increases rigidity. Here, the reinforcement layer (14
) If the inner upper edge of the wall is made too high, it may reduce distortion in the heated area and prevent separation at the outer upper edge, or conversely, the inner upper edge will be located in the flex zone of the sidewall, creating a new starting point for stress concentration. Therefore, overall, the improvement in durability is not sufficient. Therefore, it is desirable that the height fcl of the inner upper end from the bead base is in the range of 120 to 180% of the height d) of the rim flange from the bead base.

f, t The flange height dl of a rim normally used for tires for lifting vehicles is in the range of 36 to 46 mm, and the height of the outer upper end of the reinforcing layer) is this flange height di
It is preferable that the distance be no more than 10 mm.

This is because as the tire rotates, the outer side of the heated area undergoes a sagging deformation that corresponds to the surface contour of the rim flange, and as a result, the strain in the tire radial and circumferential shear directions is most severe near the upper end of the rim fludge in the heated area. This is because it is not preferable for the rigid step, that is, the upper end of the reinforcing layer, to be located in this region. On the other hand, if the outer upper end of the reinforcing layer is lowered too much, it will not be able to withstand the tensile strain of the main body of the case in the radial direction of the tire and the compressive strain of the rolled up part inward in the radial direction of the tire, resulting in sudden loads and lateral stress. If this occurs, problems such as so-called ply shedding may occur. Therefore, it is desirable that the upper end of the reinforcing layer is not lower than the rim flange height dl by more than lQmm.

Further, the difference between the winding portion upper end height bl and the outer upper end height +a+ of the metal cord reinforcing layer is preferably in the range of 8 to 15 mm. Note that if the upper end height b) of the winding portion is set to 68 mm or more, the region will be severely bent, and comb peeling will occur due to the difference in rigidity at the upper end. In addition, the metal cord reinforcement layer and carcass comb have a 100% modulus of 40~
70 kg/am2, preferably 55-65 kg/
cm2 comb, layer thickness 1.0~2,
A range of 5 mm is desirable from the viewpoint of reinforcing the heat section and suppressing distortion. Further, the cords of the metal cord reinforcing layer are arranged so as to intersect with the coat of the carcass ply at an angle of 400 to 75 degrees, preferably 50 degrees to 60 degrees,
The number of embedded cords is 20 to 45 ences/5 cm
It is desirable that

Next, in the tire of the present invention, Comstock is interposed between the case main body (ha) and the winding part (Ilb), and the Comstock extends from the bottom adjacent to the bead core outward in the tire radial direction so as to gradually decrease in thickness. The rubber stock is adjacent to the heat core (12) and includes a high elastic rubber (15) having a thickness that gradually decreases in the direction of the sidewall, and the high elastic rubber (15).
5) adjacent to the outside of and its [.

It is composed of two layers of low elasticity rubber, the upper end of which extends beyond the upper end of the high elasticity comb (15). Here, high elastic rubber (15
) serves to suppress the elongation stress acting mainly on the inside of the bead portion together with the metal cord reinforcing layer (14), and its upper end exceeds the upper end of the reinforcing layer (14) and its height is Ll.
) is usually 1.5d~4. It is set within the range of Od. In addition, the high elasticity rubber (15) is 100% Monyrus, which is 50 to 11
A range of 0 kg/cm2 is preferred. The low elasticity rubber (16) is attached to the rolled-up portion (l) of the carcass ply.
In order to alleviate compressive strain in the vicinity of lb) and effectively prevent cord-rubber peeling in the vicinity, the winding part (
Ilb) and the reinforcing layer (14) so as to adjoin or cover the outer upper ends thereof, and the upper end height L is 3d to 6.
It is set within the range of d. Furthermore, the low elasticity rubber (16) is 1
A material having a 00% molecular weight of 18 to 60 kg/cm2, preferably 23 to 85 kg/cm2 is suitably used.

Although the rubber stock can be made of a single layer, as shown in the figure, by using a two-layer structure, the rigidity gradually decreases from the bottom of the heat section toward the sidewall, effectively preventing stress concentration at the outer upper end of the reinforcing layer, and increasing durability. This can further improve performance.

In the present invention, a cover comb made of an organic fiber cord layer, a comb layer, or a short fiber embedded rubber layer can be arranged near the upper end of the reinforcing layer (14) so as to cover the outside or both the outside and inside. Further, a rubber chafer (17) is disposed outside the heat section, extending from the bottom to the area contacting the rim flanz and further to the area adjacent to the Comstock. This rubber chafer prevents rim slippage and wear, and further strengthens the heat section by integrating with reinforcing elements such as the reinforcing layer and Comstock. It is made of relatively hard rubber, such as 100% Moleyuras, and weighs 50 to 90 kg/min. c.
m2 is used.

Furthermore, there is a relatively flexible material between the rubber chafer (17) and the Comstock, for example, a 100% modulus of 20 to 20.
By disposing the intermediate rubber layer (18) with a thickness of 1.0 to 2.5 mm and a pressure of 4.0 kg/am, it is possible to effectively absorb and relieve stress strain at the bead portion.

As mentioned above, in the radial tire of the present invention, the upper end of the rolled-up portion of the carcass ply is folded back, which reduces rubber peeling caused by stress concentration at the folded upper end, making it possible to significantly improve the durability of the bead part. .

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of the heat section of a conventional tire;
The figure shows a sectional view of the heat section of the tire of the present invention. 11... Carcass 14... Reinforcement layer 1
1a... Case main part 15... High elastic comb 1
1b... Carcass winding part 16... Low elasticity comb 12... Bead core 17... Rubber chafer = 18... Intermediate rubber layer Patent applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent attorney Yoshihira Nakamura No. Figure 1

Claims (1)

[Scope of Claims] (1) Both ends of at least one carcass ply made of a rubberized layer of radial or semi-radial arranged cords are rolled up around a heat core, and the upper end of the rolled up part is folded back, whereby the carcass A rubber stock extending in the tire radial direction from the bottom adjacent to the heat core is arranged between the main body part of the case to be formed and the rolled-up part, and a rubber stock is arranged from the outside of the heated part through the bottom to the inside so as to surround the rolled-up part of the carcass. 1. A radial tire comprising: a reinforcing layer extending from above, the outer upper end of which has a height that does not exceed the upper end of the rolled-up portion. (2) A patent claim in which the cord of the carcass is a metal cord (
7) The radial tire described in Range 1. (8) The radial tire according to claim 1, wherein the reinforcing layer is an organic fiber cord layer or a metal fiber cord layer. (4) The radial tire according to claim 1, wherein the inner upper end of the heating part of the reinforcing layer is arranged at a height exceeding the upper end of the rolled-up part. (5) The claim that the rubber stock is composed of two layers: a high-elasticity comb placed adjacent to the heat core and a low-elasticity rubber placed adjacent to the high-elasticity comb and on the sidewall side. The radial tire described in item 1.