JPH02200502A - Pneumatic tire and manufacturing method therefor - Google Patents

Abstract

PURPOSE:To improve uniformity in a tire having a belt reinforcement layer of 0 deg. in its cord angle, by making an angle of splice part of a belt reinforcement layer smaller than an appointed angle in relation to the peripheral direction of a tire, and backing a thin rubber sheet to the back side thereof. CONSTITUTION:A belt reinforcement layer 1 having its cords 1c arranged mutually in parallel is cut on both ends (a), (b) thereof in an angle theta smaller than 20 deg. in relation to the peripheral direction of a tire, and is backed at its rear face with a thin unvulcanized rubber sheet 2 having length (1) corresponding to the amount of one round of tire (peripheral length of a part on which the belt reinforcement layer 1 is arranged). Relation between position, in longitudinal direction, of the rubber sheet 2 and the belt reinforcement layer 1 is set so that one end part (a) is backed with the rubber sheet 2 and the other end part (b), is not backed. Sticking of the reinforcement layer 1 is carried out in mutual abutment of rubber sheets 2 at a position 7. According to this constitution, uniformity can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic tire having a belt reinforcing layer having a cord angle of substantially 0° with respect to the tire circumferential direction, and a method for manufacturing the same.

[Conventional technology]

Conventionally, tires are known in which the entire surface or edge portions of a belt layer made of a steel belt or the like disposed in a tread portion are covered with a belt reinforcing layer whose cord angle with respect to the tire circumferential direction is substantially θ''.

In the belt reinforcing layer, the splice parts in the tire circumferential direction form a step part in which the end parts are overlapped, so if these splice parts are concentrated in one place in the tire circumferential direction, the uniformity of the tire will be reduced. . For this reason,
Generally, the splice portion is formed to have a cut end oblique to the tire circumferential direction, and is dispersed in the tire circumferential direction. The smaller the angle of the splice portion with respect to the tire circumferential direction, that is, the splice angle, the more the splice portion can be dispersed in the tire circumferential direction, thereby improving the uniformity of the tire.

By the way, when splicing the ends of the belt layer in the tire circumferential direction, in the case of a general belt layer where the cord angle with respect to the tire circumferential direction is oblique, the splice direction and the cord direction at the splice part can be made parallel. , the splicing operation can be performed relatively easily. However, in the case of a belt layer where the cord angle with respect to the tire circumferential direction is substantially 0'', such as the above-mentioned belt reinforcing layer, both ends of the cords are butted against each other and overlapped, so the splice portion is made to have a uniform width. Difficult to splice.

As mentioned above, the smaller the splice angle in the tire circumferential direction, the more advantageous it is to improve tire uniformity, but if the splice angle is less than 20 degrees, it becomes more difficult to improve tire uniformity because the splice length relative to the belt width becomes longer. As a result, it is inevitable that work efficiency will be significantly reduced.

Moreover, since the narrow belt reinforcing layer is easily deformed, workability is further reduced.

[Problem to be solved by the invention]

It is an object of the present invention to connect a belt reinforcing layer with a cord angle of substantially O'' with respect to the tire circumferential direction to a splice angle of 2.
To provide a pneumatic tire that can splice at 0° or less with good workability and achieve high uniformity, and a method for manufacturing the same.

[Means to solve the problem]

An object of the present invention is to provide a tire in which a belt reinforcing layer having a cord angle of substantially θ° with respect to the tire circumferential direction is disposed between a tread and a carcass layer, and to reduce the angle of the splice portion of the belt reinforcing layer in the tire circumferential direction. This can be achieved by using a pneumatic tire whose back side is lined with a thin rubber sheet and the angle is 20° or less.

In addition, as a manufacturing method, the splice part of the belt reinforcing layer is cut at an angle of 20 degrees or less with respect to the tire circumferential direction, and the back side is lined with a thin rubber sheet with a length corresponding to the tire outer circumference. This can be achieved by wrapping a belt reinforcement layer lined with a rubber sheet around the outside of the carcass layer and splicing the ends together.

The present invention will be explained below with reference to the drawings.

FIG. 3 is a cross-sectional view of a tread portion of a radial tire according to an embodiment of the present invention.

As shown, belt layers 5, 5' are arranged between the carcass layer 4 and the tread 3. This belt layer 5.5°
The reinforcing cords are arranged diagonally to the circumferential direction of the tire,
Furthermore, the adjacent belt layers 5.5'' intersect with each other. A highly rigid steel cord or the like is used for this reinforcing cord.

At both edge portions of the belt layer 5.5'', belt reinforcing layers 1.
The reinforcing cords of these belt reinforcing layers I on which No. 1 is arranged are arranged at a substantially cord angle of 06 with respect to the tire circumferential direction.

This belt reinforcing layer 1 suppresses the edge part of the belt layer 5, 5° by arranging the reinforcing cord in the tire circumferential direction,
The hoop effect prevents the edge portion from curling up during high-speed driving.

In the illustrated embodiment, the belt reinforcing layer 1 covers only the edge portion, but it may be made to cover the entire surface of the belt layer 5, 5° with only one layer.

In manufacturing the tire of the present invention, the belt reinforcing layer 1 is formed in advance into a structure as shown in FIG. 1, and then placed above the carcass layer in the green tire manufacturing process. As shown in FIG. 1, the belt reinforcing layer 1 in which the cords lc are arranged parallel to each other has both ends a,
b is cut at an angle θ of 20″ or less with respect to the tire circumferential direction, and on the back side thereof is a thin unvulcanized material with a length l corresponding to one circumference of the tire (the circumference of the part where the belt reinforcing layer is arranged). The rubber sheet 2 is lined with the rubber sheet 2.Moreover, the longitudinal positional relationship between the rubber sheet 2 and the belt reinforcing element 1 is such that one end a is lined with the rubber sheet 2.
The other end is not lined. Therefore, on the end a side of the belt reinforcing layer 1, there is an exposed portion 2a where only the rubber sheet 2 remains.

In manufacturing a tire, the combination belt of the belt reinforcing belt layer and the rubber sheet 2 shown in FIG. 1 is attached to both ends of the belt layers 5 and 5 degrees, respectively, during the manufacturing process of the green tire. This pasting is performed from the side where the exposed portion 2a of the rubber sheet 2 exists (the end a side of the belt reinforcing layer 1), and the rubber sheet 2 is pasted downward. Then, after one round of the tire, the last opposite end is spliced to the first attached end a, as shown in FIG.

In pasting the belt reinforcing layer 1 in this manner, the rubber sheet 2 is butt-jointed at the position 7. Further, the exposed portion 2a of the rubber sheet 2 is positioned by gluing the end portions to facilitate splicing to the end portion a with a uniform width, thereby forming a uniform splice portion 6. Furthermore, by providing a splice with a splice angle of 20'' or less in the tire circumferential direction, the uniformity of the tire can be improved.

The thin rubber sheet used in the present invention must be made of adhesive unvulcanized rubber. However, if the adhesiveness is too strong, workability may deteriorate, so a semi-cured rubber sheet in a semi-vulcanized state is preferable.

Also, the length of the thin rubber sheet! In order to further improve the uniformity of the tire, it is desirable that the length corresponds to one circumference of the tire, and that the ends of the rubber sheets do not overlap. Furthermore, since the rubber sheet is provided to improve workability, it is desirable to make it as thin as possible without impairing workability.

Usually 1.0a+m or less, more preferably 0.6+++
It is better to keep it below m.

In the present invention, any conventionally known reinforcing cords can be used as the reinforcing cords constituting the belt reinforcing layer, and are not particularly limited. Examples include textile cords such as nylon 6, nylon 66, and polyester fibers.

In the embodiment shown in FIG. 3, the belt reinforcing layer of the present invention is exemplified for reinforcing the main belt layer, but it can of course also be applied to reinforcing a part of a general belt layer.

〔Example〕

Belt-shaped reinforcing layers in which nylon cords are arranged parallel to each other are arranged at 10', 20', and 20' in the cord direction, respectively.
Diagonal cuts were made at 30", 60" and 90@.

After each of these belt reinforcing layers was lined with an unvulcanized rubber sheet having a thickness of 0.6+++m, semi-curing was performed, and five types of belt reinforcing layers 1. It,
III, IV and ■ were prepared.

The cord directions of each of these belt reinforcing layers are arranged in the tire circumferential direction, and the cutting angles are 10', 20',
The splice angles θ with respect to the tire circumferential direction were made equal to 30@, 60@, and 90@, and as shown in FIG. 3, five types of tires of the same size were manufactured to be used as edge covers of the belt layer of a radial tire.

The splice angles of the belt reinforcement layer are lO'' and 2, respectively.
Tires (2) and (2) with a splice angle of 30', 60'' and 90@ are comparative tires.

On the other hand, a conventional tire of the same tire size was prepared by cutting the belt-shaped belt reinforcing layer at 30°, 60'' and 90@ with respect to the cord direction and using it as an enclosure cover for the belt layer without lining it with a rubber sheet. , ■ and ■ were produced.

Incidentally, we attempted to manufacture tires with cutting angles of 10' and 20'', but the splices were significantly disturbed, so we gave up on completing the tire.

Radial force variation (RFV), which indicates uniformity on the tire circumference, was measured for the above eight types of tires 1 to 2. The results were as shown in Figure 4.

Cocote, RPV is a measurement value measured in accordance with JASOC607r Automobile Tire Uniformity Test Method.

From Figure 4, the splice angle θ of the belt reinforcement layer is 206
Comparative tires that exceed ■, ■, ■, conventional tires ■, ■
, ■ both have high RPV and poor uniformity. On the other hand, tires I and H of the present invention, in which the splice angle θ of the belt reinforcing layer is 20' or less, have a lower R
It can be seen that the FV is extremely low and the uniformity is excellent.

Also, from Fig. 4, the splice angle θ is 30' or 60''.
For tires lined with a rubber sheet, the RFV is higher than that without lining, and the splice angle is 9.
It can be seen that this relationship is reversed for the 0° angle.

〔Effect of the invention〕

According to the present invention, the belt reinforcing layer whose cord angle with respect to the tire circumferential direction is substantially Oo is spliced at a small splice angle of 20 degrees or less with respect to the tire circumferential direction, and the back surface thereof is lined with a thin rubber sheet. Therefore, the splice angle 20, which was previously considered difficult to manufacture.
The splices can be widely distributed around the tire circumference, making it possible to create a tire with excellent uniformity.

In addition, even though the belt reinforcing layer is spliced at a small splice angle of 20" or less during tire manufacturing, the back side is lined with a thin rubber sheet before splicing, which improves splicing work efficiency. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an example of the belt reinforcing layer before it is used in manufacturing the tire of the present invention, Fig. 2 is a plan view showing the splice portion when the belt reinforcing layer is attached, and Fig. 3 4 is a partial sectional view showing an example of the pneumatic tire of the present invention, and FIG. 4 is a diagram showing the relationship between the splice angle and uniformity of the tire of the present invention, a comparative tire, and a conventional tire. 1... Belt reinforcement layer, 2... Rubber sheet, 3...
Tread, 4... Carcass layer, 5.5゛... Belt layer, 6... Splice part. Figure 1

Claims (1)

[Claims] (1) In a tire in which a belt reinforcing layer is arranged between the tread and the carcass layer and the cord angle with respect to the tire circumferential direction is substantially 0°, the angle of the splice portion of the belt reinforcing layer with respect to the tire circumferential direction is A pneumatic tire with a cord angle of 20° or less and lined with a thin rubber sheet on the back side (2) A pneumatic tire with a belt reinforcing layer arranged in the tread part, the cord angle of which is substantially 0° with respect to the circumferential direction of the tire. In the manufacturing method, the splice part of the belt reinforcing layer is cut at an angle of 20 degrees or less with respect to the tire circumferential direction, and the back side is lined with a thin rubber sheet with a length corresponding to the tire outer circumference. A method of manufacturing pneumatic tires in which a belt reinforcing layer lined with a sheet is wrapped around the outside of the carcass layer and the ends are spliced together.