JPH02296507A - Radial-ply tire for automobile - Google Patents

Abstract

PURPOSE:To reduce the winding time by winding a cored rubber strip being wound in coil form and thereby forming a cap ply on a peripheral part of a belt part as much as a smaller pitch than its width, and overlapping adjacent coils at a part of width. CONSTITUTION:A tire 1 is laminated with two belts 3a, 3b at the upper part of a carcass 2, and a cap ply 5 consisting of a cored rubber strip 4 is overlapped at the upper part of these belts, while tread rubber 6 is further stack on this upper part. In this case, the cored rubber strip 4 is formed into a ribbon form with the specified width by a steel cord 4a and a rubber layer 4b paralleled at a specified interval. Then, the cored rubber strip 4 is rolled on each top face of these belts 3a, 3b at a smaller pitch than its width. In addition, the rubber strip 4 is bent at a central part of the width, through which such a possibility that a clearance might be produced in a gap with the belt 3b is brought to nothing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a radial tire for automobiles having a cap ply on the outer periphery of a belt portion.

(Prior Art) In order to reinforce the belt portion, it is possible to provide a cap ply on its outer periphery, which is composed of a large number of reinforcing cords in the circumferential direction of the tire and a covering rubber layer, and has a width comparable to that of the belt portion. Are known. As a means for forming this cap ply, a narrow cored rubber strip consisting of 1 to 8 reinforcing cords and a covering rubber layer may be wound in a coil shape from one end of the belt section to the other end. Japanese Unexamined Patent Publication 1986
-203803 publication and JP-A-62-251203
It is disclosed in the publication No.

(Problem to be Solved by the Invention) When a cored rubber strip is wound into a coil to form a cap ply, the winding start end and the end of the winding are different from each other when a cored rubber strip is wound into a coil to form a cap ply. There is no seam formed due to overlap with the end of the winding, which improves the uniformity of the tire. On the other hand, even when forming the cap ply in two layers, adjacent coils were wound so as not to overlap each other. There was a problem in that it took a long time to wrap the winding. In order to shorten the time required for one winding, when the width of the cored rubber strip is increased, the direction in which the cored rubber strip is wound, that is, the direction of the reinforcing cord, is greatly inclined with respect to the circumferential direction of the tire. , the purpose as a cap ply cannot be achieved.

This invention enables the winding of a cored rubber strip to be performed in a shorter time, and also allows the winding direction to be made at the same angle of inclination as the conventional method.

(Means for Solving the Problems) In the present invention, the above-mentioned cored rubber strip is wound at a pitch smaller than its width, and adjacent coils made of the cored rubber strip are overlapped with each other over a part of the width. The above pitch is determined by the desired number of plies of the cap ply; for example, in the case of 2 plies, it is wound at a pitch of 1/2 the width of the cored rubber strip,
In the case of 3 ply, the winding is performed at a pitch of 1/3 of the size.

The width of the cored rubber strip can be increased depending on the number of plies, and in the case of 2 plies, the width is 10 to 2.
When 0+n++ is 3 ply, 15 to 30 nn is preferable. In addition, the thickness of the reinforcing cord is 0.50~
1.00mm, and the arrangement pitch is 0.8 to 1.2
Each of m is preferable.

In addition, how to wrap the above-mentioned cored rubber strip.

The process is performed on a belt formed on a belt forming drum of a secondary forming machine, and then a tread cap is applied, and the resulting laminate of the belt, cap ply, and tread cap is deformed into a toroidal shape on a shaving drum. It can be formed into a green tire by being attached to a part of the carcass. In addition, the belt is formed on an auxiliary drum prepared separately from the belt forming drum, and the above-mentioned cored rubber strip is wound around this to form a cap ply, and the resulting laminate of the belt and cap ply is It can be attached to a belt forming drum and a tread cap can be attached thereon. Furthermore, a cored rubber strip can be wound directly onto an auxiliary drum to form a cap ply, which can be applied to a belt on a belt-forming drum, and then a tread cap can be applied.

(Function) When winding a cored rubber strip in a coil shape from one end of the cylindrical part to the other end, and applying a tension of 20 to 160 g to this cored rubber strip, it is possible to wind the cored rubber strip according to the pitch. The edges of the cored rubber strips of adjacent coils overlap to form a multilayer cap ply with no gaps between them. For example, when wound with a pitch of 1/2 of the width of the cored rubber strip, 2 plies of cap ply are formed, and when wound with a pitch of 1/3 of the above width, 3 plies of cap ply are formed. be done. Also, when wound with a pitch of 2/3 of the above width,
A cap ply is formed in which two layers of ribbon-like portions and a single layer of ribbon-like portions alternate. Therefore, when forming a two-ply cap ply, if a cored rubber strip that is twice the width of a conventional cored rubber strip is used, the winding time will be reduced by half, and the wrapping time will be reduced by half. The inclination angle with respect to the tire circumferential direction is the same as before, and if a rubber strip with the same width as the conventional cored rubber strip is used, the time required for one wrap is the same and the inclination angle is halved.

(Example) In the radial tire 1 for a passenger car shown in FIG.
are stacked on top of each other, and tread rubber 6 is further pasted on top of the tread rubber. As shown in Fig. 2, the above-mentioned cored rubber strip 4 consists of 12 strips with a diameter of 0.75nw lined up at 1m intervals.
Width 12 consisting of n steel cord 4a and rubber layer 4b
This cored rubber strip 4 is placed on belts 3a and 3b on a belt forming drum (not shown) at a pitch of 6 mm, which is half the width of the 12n bait described above. The cap ply 5 described above is formed by winding it. When the cored rubber strip 4 is wound around the belt forming drum while rotating, a tension of 20 to 160 g is applied to the cored rubber strip 4, so that the cored rubber strip 4 becomes as shown in FIG. Bend at the center of the width as shown, and belt 3
A two-ply cap ply 5 with no gap nn between the cap ply 5 and b is formed.

(Effects of the Invention) In the automobile radial tire of the present invention, the cap ply on the outer periphery of the belt portion is formed by coiling a ribbon-like cored rubber strip consisting of a plurality of parallel reinforcing cords and a covering rubber layer. Since it is rolled and formed, there is no stepped part due to the seam between the beginning and end of the winding, and the uniformity of the tire is good. The core strips forming adjacent coils are wound so that they partially overlap each other.
When forming a cap ply with N plies, if the width of the cored rubber strip is N times the width of the conventional one and the winding pitch is set to 1/H of the width, the winding time will be reduced to 1/H of the conventional width.
Moreover, the winding angle of the reinforcing cord can be kept the same as before, and the width of the cored rubber strip can be kept the same as before, and the winding pitch can be set to 1/N of the width. The time required for one winding is the same as that of the conventional method, and the angle of winding can be reduced to 1/N of that of the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a tread portion according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a cored rubber strip, and FIG. 3 is an enlarged sectional view of a cored rubber strip when it is wound. 1: Automobile tire, 2: Carcass, 3a, 3b: Belt, 4: Rubber strip with core, 4a: Reinforcement cord,
4b: rubber layer, 5: cap ply. Patent applicant: Toyo Rubber Industries Co., Ltd. Agent Patent attorney: Yoshi 1) Tsukasa Ryo

Claims (1)

[Scope of Claims] [1] In a radial tire for automobiles in which a cap ply is formed by winding a cored rubber strip formed by rubber-coating a plurality of reinforcing cords arranged in parallel around the outer periphery of a belt portion in a coil shape. A radial tire for an automobile, characterized in that the above-mentioned cored rubber strip is wound at a pitch smaller than its width, and adjacent coils made of the above-mentioned cored rubber strip overlap each other at a part of the width.