JPS5881806A - Recapped tire - Google Patents

Abstract

PURPOSE:To relax stress concentration in a cushion rubber layer in an effective manner, by making up cushion grooves on both sidepieces of a tread rubber layer in the circumferential direction of a tire. CONSTITUTION:A recapped tire 1 is formed by sticking a pre-vulcanized tread rubber layer 2 to a case body 4 into an unit body while interposing a cushion rubber layer 3 in between, and cushion grooves 8 where an upper lip 6 and a lower lip 7 are closed up in time of tire grounding are made up on both sidepieces of the tread rubber layer 2 in the circumferential direction. As the cushion grooves 8 are provided on both the sidepieces 5, the stress to be transmitted from the direction of tread grounding is relaxed by dispersion along the grooves so that stress concentration on both ends 3a of the cushion rubber layer 3 can be obviated effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a retreaded tire, in particular a case body from which a worn tread portion has been peeled off and removed, and a new vulcanized tread rubber layer pasted and integrated with a cushion rubber layer interposed therebetween. The tire is provided with buffer grooves on both sides of the tread rubber layer to alleviate stress concentration in the cushion rubber layer and to prevent peeling at both ends of the cushion rubber layer. This invention relates to retreaded tires that are perforated in the same direction.

Generally, as tires are used, the tread rubber gradually wears out and the tread pattern eventually disappears, but in this case, even if the tire itself is strong enough to withstand use, the lack of a tread pattern provides stable handling. This will significantly impair vehicle characteristics such as performance and braking performance. Then, remove the worn or damaged tread rubber from the case body.

Retreaded tires in which a new vulcanized tread rubber layer is integrated with a cushion rubber layer interposed therein are widely used. With this type of retreaded tire, the two tires do not exhibit the same deformation behavior due to reversal deformation.

In particular, stress is concentrated at the boundary between the tread rubber layer and the case body, that is, the thin cushion rubber layer. Furthermore, since the tread rubber layer is pre-vulcanized, it cannot necessarily be said that its adhesive strength to the case body is sufficient. Therefore, there is a problem in that the cushion rubber layer partially peels off from the case body, and this spreads to the circumferential direction and inside of the tire.

Therefore, in order to solve the above problem, the inventor conducted extensive research on the cracking phenomenon at both ends of the cushion layer of a retreaded tire, considering the relationship between the shape of both side surfaces of the tread rubber layer and the stress distribution based on the shape. By drilling one buffer groove in the tire circumferential direction on both sides of the tread rubber layer where the upper lip and lower lip join together when the tire contacts the ground, stress concentration at both ends of the cushion rubber layer can be effectively alleviated. It turns out that it can be achieved. The present invention is based on this knowledge, and its object is to provide an effective way to reduce stress concentration at both end portions of a cushion rubber layer.

Embodiments of the retreaded tire of the present invention will be described below with reference to the drawings.

FIG. 1 shows a plan view of nine parts of the retreaded tire of the present invention. Figure t
In this case, the retreaded tire of the present invention (Yukiyo) is formed by pasting and integrating a pre-vulcanized tread rubber layer (2) on a case body (4) with a cushion rubber layer (3) interposed therebetween, and the tread rubber Both side surfaces (5) of the layer (2) are provided with buffer grooves (2) where the upper lip (6) and lower lip (7) connect when the tire touches the ground.
8) are bored in the circumferential direction of the tire. Generally, when a tire undergoes repeated deformation during running, the stress caused by contact with the ground is distributed from the tread contact surface to both sides and the cushion rubber layer (
3) Stress concentration occurs on both sides (3a) due to the rigid fault in the area. Therefore, the retreaded tire of the present invention has buffer grooves (8) arranged on both sides (5) of the tread rubber layer.

The stress transmitted from the direction of the tread contact surface is relaxed and dispersed in the grooves, and the stress transmitted from the direction of the tread contact surface is relaxed and dispersed, and
) can be effectively prevented from stress concentration. Particularly in radial tires for heavy vehicles, there is a phenomenon of shoulder drop wear on a part of the tread shoulder, and therefore it is generally avoided to reduce the rigidity of the tread by providing the tread IIl in this value range. (8)
When the tire touches the ground, the upper lip (6) and the lower lip (force) are connected, so there is no reduction in the rigidity of a part of the tread shoulder, and there is no fear of debris falling and wear.

The buffer groove (8) of the present invention will be explained below with reference to FIG. 2, which shows an enlarged sectional view of FIG.

The distance (H) between the upper lip (6) and lower lip (7) of the buffer groove (8)
) is 0°5~3. Set to Off range.゛This interval (H
) exceeds 3.0 mm, it becomes difficult for the upper lip (6) and lower lip (7) to connect when touching the ground, reducing the rigidity of a part of the shoulder, and if Q is less than 5 mm, it becomes difficult to manufacture. . In addition, forming the buffer groove (8) with a main part (9) that connects to each other upon grounding and a bore part (g) that always maintains a space will be more effective in relaxing and dispersing stress.

The inner cavity a! 3), that is, the groove bottom of the buffer groove (8), is curved to form a circular arc, thereby preventing cracks from occurring in the groove bottom due to repetitive bending deformation. Next, the upper lip (6) has a stress t transmitted from the tread contact surface, whereas the lower lip (needs to deform in the force direction and support the stress, therefore its depth Wl) is at least i
It is preferable that there be am'. But this deep W
, ) exceeds a certain range, the stress fraction effect caused by the inner cavity e decreases, so it is preferable to rub the inner cavity e for less than 5 m. Next, the depth from the lower edge of the tread (11) to the bottom of the buffer groove is usually the depth of the upper lip (wl)i, which is 1~' of the arc radius (R) of the inner cavity! ;Set to the range of the sum of double numbers. The area corresponding to the depth W)1 becomes the area where the stress is least applied due to the effect of the buffer groove, but this area does not increase as the arc radius 0() of the inner cavity increases. The area of stress distribution becomes wider, and therefore the depth W) needs to be larger.

FIG. 3 is a sectional view of essential parts showing another embodiment of the retreaded tire of the present invention. In the figure, the inner cavity (IO) of the buffer groove (8)
is placed above the main part of the tread, and in this case, stress distribution is mainly done at the upper part of the tread, so the upper lip part is located at 6.
Deformation is likely to occur. Therefore, the depth of the upper lip W2
) is relatively deep.

For example, it is preferable to set the range from 3 to 101 m. FIG. 4 is a sectional view of a main part of a retreaded tire having a buffer groove (8) of another shape. In this embodiment, the width is approximately the same from the shield part to the groove bottom part. Here the buffer groove (8)
The angle (α) between the bottom surface of the tread layer (TB) and the bottom surface (TB) of the tread layer is usually 0~
．． Although it is set to a range of 60°.

This is because the larger the angle, the easier the release from the mold after the tread rubber layer has been added, which can be said to be advantageous, but it has the disadvantage that the inverse t-stress relaxation effect decreases.

In each of the above embodiments, only one buffer groove is arranged, but it is also possible to provide multiple buffer grooves, and the shield part of the buffer groove has a part that connects and a part that does not connect after touching the ground. It is also possible to adopt a shape in which they are arranged intermittently in the circumferential direction.

However, as mentioned above, the retreaded tire of the present invention has buffer grooves arranged on both sides of the tread rubber layer.

The stress transmitted from the tread contact surface is alleviated by the groove, effectively preventing stress concentration at both ends 01 of the cushion rubber (3), and making it possible to reduce cracks in this area by 4 tons. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a retreaded tire of the present invention, and FIGS. 2 to 4 are cross-sectional views of a main part showing the shape of a buffer groove in a retreaded tire of the present invention. Patent applicant: Sumitomo Rubber Industries, Ltd. Representative Patent Attorney Yoshihira Nakamura Figure 1 Figure 3 B

Claims (4)

[Claims] (1) In a retreaded tire in which a vulcanized tread rubber layer is integrally attached to a case body with a cushion rubber layer interposed therebetween, both sides of the tread rubber layer have an upper layer portion and a lower layer portion that are formed when the tire is in contact with the ground. A retreaded tire characterized by having a buffer groove formed in the circumferential direction of the tire to which the tires are joined. (2) The distance between the upper lip and shoulder of the buffer groove is 5 to 3 cm. On
A retreaded tire according to claim 1, which falls within the scope of claim 1. (3) The retreaded tire according to claim 1, wherein the groove bottom of the buffer groove forms an arc. (4) The buffer groove is formed of shoulders that connect with each other when touching the ground, and an inner cavity that does not connect with each other.
Retreaded tires as described in section.