JPS5851602Y2 - Retreaded tires - Google Patents

Description

[Detailed description of the invention] The present invention is an improvement of a retreaded tire in which a pre-vulcanized tread is bonded to a base tire via cushion rubber, and the bonded portion, which appears in an annular shape on the tire surface, is covered with a reinforcing layer. It is related to.

Conventionally, in this type of tire, a cushion rubber layer is exposed in an annular shape on both sides of the tread.The cushion rubber layer is a relatively soft rubber, and when the tire is used, stress is concentrated due to the force acting from the ground contact surface. easy.

In particular, stress tends to concentrate near both end portions exposed on both side surfaces of the tire.

In the retreading process, the cushion rubber layer is vulcanized after the vulcanized tread is bonded to the base tire via the unvulcanized cushion rubber layer.

During vulcanization, the material is covered with a thin bag and placed in a rim-assembled vulcanizer for vulcanization.

At that time, the heating by steam is carried out through a thin bag on both side surfaces of the cushion rubber layer of the tire, i.e. near both ends, so it is more likely to be heated beyond proper vulcanization compared to the area near the center which is heated through the tread. Normally, there is a tendency for deterioration due to overvulcanization.

In other words, in conventional tires of this type, tear resistance is weakened near the end surfaces on both sides of the tire where the cushion rubber layer is exposed.

Therefore, in addition to the above-mentioned stress concentration, cracks were likely to occur in the cushion rubber layer at both end portions of the tire.

This also affects the durability of retreaded tires.

Furthermore, this type of retreaded tire has the problem that small steps are likely to occur on the side surface of the tire when the base tire and tread are connected, and the steps impair the appearance.

This invention attempts to solve each of the problems mentioned above.

This invention will be explained below based on the illustrated embodiments.

In FIG. 1, 1 is a base tire, 2 is a tread, and 3 is a cushion rubber layer.

This structure is the same as a conventional retreaded tire.

In this retreaded tire, a reinforcing layer 4 is applied over both the base tire 1 and the tread 2 so that the cushion rubber layer 3 covers the joint portion between the base tire 1 and the tread 2 on both sides of the tire where the cushion rubber layer 3 is annularly exposed. It is different from the conventional one in that it is glued together.

As shown in FIG. 2, the reinforcing layer 4 is made by covering a fiber tissue layer 5 with a rubber layer 6 on one or both sides.

The fiber tissue layer 5 is made of, for example, a woven fabric, and its material is preferably vinylon, nylon, cotton, etc., and the fiber cord 7 has a diameter of about 65 mm in the radial direction x-x as shown in FIG.
They intersect each other at an angle .alpha. of less than .degree., preferably about 45.degree. (after coating adhesion, an angle .alpha. of less than about 800).

When the angle α of the fiber cord before the coating is bonded exceeds about 65°, the width of the reinforcing layer 4 is difficult to change, so the efficiency of the bonding process is poor.

The rubber layer 6 is made of, for example, a combination of natural rubber and synthetic rubber, or natural rubber and gum rubber, so that the fibrous tissue layer 5 is not exposed to the surface, and the joint between the base tire 1 and the tread 2 is smoothed. used for a purpose.

In manufacturing this retreaded tire, a tread 2 which has been shaped and cured in advance is adhered to a base tire 1 via an unvulcanized cushion rubber layer 3, and an unvulcanized reinforcing layer 4 is further adhered to the cushion rubber layer 3. The rubber layer 6 is simultaneously vulcanized and completed.

During the vulcanization, both ends of the cushion rubber layer 3 on both side surfaces of the tire are covered with the reinforcing layer 4, so that partial over-vulcanization is prevented.

In this retreaded tire, the positions on both sides of the tire of the cushion rubber layer 3, where stress tends to concentrate during use, are reinforced with the fibrous tissue layer 5, which has a high resistance to tearing. Since over-vulcanization is prevented, not only does it not cause cracking and have improved durability, but also the fiber cords 7 of the fiber texture layer 5 are bent at an angle of less than about 65 degrees with respect to the radial direction before coating and bonding. Since they intersect with each other at an angle, the work of attaching the reinforcing layer 4 becomes significantly easier.

Furthermore, in terms of appearance, even if a step occurs at the tread joint, it will be covered by the reinforcing material 4 and will not be noticeable.

Regarding the dimensions of the reinforcing layer 4 in the examples, the width of the strip should preferably be about 5 to 30 mm, taking into consideration strength, appearance, and workability, and the thickness should be about 5 to 30 mm, taking into consideration strength and appearance. and 0
．． Approximately 3 to 1.5 h is good.

As described above, according to this invention, it is possible to provide a retreaded tire that can prevent cracking on both sides of the tire, especially at the joint between the base tire and the tread, and has improved durability, as well as improved workability for attaching the reinforcing layer. .

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a tire according to an embodiment of the present invention, FIG. 2 is an enlarged view of a reinforcing layer, and FIG. 3 is an explanatory diagram showing the intersecting relationship of cords in a fibrous tissue layer. DESCRIPTION OF SYMBOLS 1... Tire, 2... Tread, 3... Cushion rubber layer, 4... Reinforcement layer, 5... Fibrous tissue layer, 6
...Rubber layer, 7...Fiber cord.

Claims (1)

[Scope of utility model registration request] In a retreaded tire in which a vulcanized tread is bonded to a base tire via a cushion rubber layer, and the bonded portion, which appears annularly on the tire surface, is covered with a reinforcing layer, the fiber cords constituting the reinforcing layer extend in the radial direction. A retreaded tire characterized by intersecting each other at an angle of less than about 80° with respect to the tire.