JPH05154938A - Manufacture of pneumatic radial tire - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing pneumatic radial tires having a high uniformity while taking a lap-splice method with advantageous workability as a base. CONSTITUTION:In a manufacture of pneumatic radial tires wherein both ends of a rubber coated carcass material 4a reinforced by a plurality of reinforcing cords arranged transversely are spliced into a lap-shape in order to form a carcass layer 4, before splicing both ends of the carcass material 4a, the reinforcing cords 6 are extracted from either end, and subsequently both ends can be spliced into a lap-shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a pneumatic radial tire, and more particularly to a method for manufacturing a pneumatic radial tire having a high degree of uniformity.

[0002]

2. Description of the Related Art Generally, in a method of manufacturing a pneumatic radial tire, a carcass layer is formed by winding a belt-shaped rubberized sheet material reinforced by a reinforcing cord in a cylindrical shape on a forming drum, and by applying both end portions of the sheet material. I try to splice. As the splicing method, there are a case where a certain width of both ends is wrapped and a case where the both ends are abutted without being wrapped.

In these two splicing methods, the latter does not form a step because it is merely abutting, which is advantageous for uniformity. However,
This butt splicing method has a problem that it is extremely difficult to butt the gaps at both ends of the sheet material to a uniform width, and it is very difficult to keep the quality constant. In addition, since the splice portion has a weak joint strength, it may be separated by an inflating operation during vulcanization molding, or a portion having a weak joint strength may be broken during use after the product is produced. ..

On the other hand, the former lap splicing method does not have problems such as difficulty in working and weak joint strength, but since the splice portion has a stepped shape, it has a problem of reducing the uniformity of the tire. Since a convex shape is formed on the side surface of the tire, there is a problem that the appearance of the tire is significantly impaired.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a pneumatic radial tire having high uniformity while being based on the former Laps Plus method which is advantageous in workability.

[0006]

According to the present invention for achieving the above object, a carcass layer is formed by splicing both ends of a rubberized carcass material in which a plurality of reinforcing cords are arranged side by side and reinforced in a lap shape. In the method for manufacturing a pneumatic radial tire configured to form, before the splicing of both ends of the carcass material, pull out the reinforcing cord from one of the ends, and then splice the both ends in a lap shape. It is a feature.

Since the reinforcing cord is pulled out from one of the both end portions to be spliced in this way and the end portion where the reinforcing cord is pulled out and the end portion which is not pulled out are overlapped with each other,
The reinforcing cords do not overlap or become overcrowded at the lap splice. Therefore, almost no step is formed in the splice portion, the uniformity of the tire is improved, and a convex shape is not formed on the side surface. In addition, since it is based on the lap splice, a large joint strength can be obtained.

[0008]

EXAMPLE FIG. 1 is a meridional sectional view showing an example of a pneumatic radial tire obtained by the manufacturing method of the present invention. Figure 1
In the above, 1 is a tread portion, and 2 is a sidewall portion. The carcass layer 4 is provided inside the tire over the tread portion 1 and the sidewall portions 2 on both left and right sides, and both end portions thereof are wound around the left and right bead cores 3 so as to be folded back from the tire inner side to the outer side. On the outer periphery of the carcass layer 4 corresponding to the tread portion 1, two belt layers 5 made of steel cord are arranged.
The steel cord of the belt layer 5 is 1 in the tire circumferential direction.
The cord angle is 0 ° to 35 °, and the layers intersect with each other.

The method of manufacturing the pneumatic radial tire having the above structure according to the present invention will be specifically described below. The reinforcing cord 6 of the carcass material 4a serves as the carcass cord of the carcass layer 4, and is made of polyester,
High-strength cords such as nylon, rayon, aramid, and steel can be used.

As shown in FIG. 4, the band-shaped carcass material 4a prepared as described above is formed by first winding the inner liner 10 made of butyl rubber or the like having a large air-impermeable property on the first molding drum 9 in a tubular shape. Then, it is wound on it and both ends are lap-spliced to form a tubular laminate 11 as shown in FIG. Alternatively, a tubular carcass material 4a is formed by performing lap splicing on another forming drum in advance, and the carcass material 4a is covered as shown in FIG. 5 to form the tubular laminate 11 as shown in FIG.

In the present invention, as described above, the carcass material 4 is placed on the first forming drum 9 or on another forming drum.
In the case of lap-splicing both ends of the cord, as shown in FIG. 2, several reinforcing cords 6 are previously pulled out from one of the both ends, and the pulled-out end of this reinforcing cord and the end not pulled out are overlapped with each other. Splice. At this time, the number of pulling out the reinforcing cords 6 is not particularly limited, but is 2 to 3
Books are desirable. Further, in the above-mentioned splicing operation, it is preferable that the end portion having the hollow portion 7 from which the reinforcing cord 6 is pulled out is on the lower side and the end portion which is not pulled out is overlapped on the upper side. In this case, as shown in FIG. 3, if a part of the rubber on the side facing each other is peeled off in advance at the splice portion, the amount of rubber is reduced and a good splice portion can be obtained. Further, in the case of peeling in this way, by sandwiching the ultra-high molecular weight polyethylene sheet 12 in advance between the portion of the rubber to be peeled off at this portion and the reinforcing cord 6 in the splice portion where the reinforcing cord 6 is not pulled out. It can be easily peeled off. Further, in the above-mentioned splicing operation, it is desirable to attach a sealing rubber sheet 8 which has been previously irradiated with an electron beam, to the lower side of the end portion having the cavity 7.

The method of forming the carcass layer from the carcass material 4a according to the present invention includes a method of directly winding the carcass layer around the first molding drum 9 as shown in FIG. 4 and a cylinder on another molding drum as shown in FIG. There is a method to shape it,
The latter method is preferable. As shown in FIG. 5, when the carcass material 4a is previously spliced into a cylindrical shape by another forming drum, a forming drum having a structure in which the outer diameter is expanded and contracted is used. When removing the material 4a, the diameter is reduced.

After the tubular laminate 11 is formed on the first molding drum 9 as described above, a bead is driven and a sidewall rubber is wound according to a known ordinary method to complete a first green tire. Next, the first green tire was transferred to a second molding drum, the center portion was expanded in diameter, and then a belt material and a tread rubber were wound around the outer periphery to complete a second green tire, which was then formed into a mold according to a conventional method. A pneumatic radial tire is completed by inserting and vulcanizing.

In the tire manufacturing method of the present invention, the reinforcing cord is pulled out from one of the both ends of the carcass material as described above, and is spliced by wrapping it with the end that is not pulled out. Since the reinforcing cords do not overlap with each other or become overcrowded, almost no step is formed, the uniformity of the tire is improved, and no convex shape is formed on the side surface. Also, because it is based on lap splice,
A large bonding strength can be obtained.

[0015]

As described above, according to the present invention, when the carcass material is lap-spliced, the reinforcing cord is pulled out from one of the both end portions of the carcass material, and the pulled-out end portion is not pulled out. Because it wraps with the end, there is almost no step formed in the lap splice, improving the uniformity of the tire,
In addition, no convex shape is formed on the side surface. In addition, since it is based on the lap splice, a large joint strength can be obtained.

[Brief description of drawings]

FIG. 1 is a meridional sectional view showing an embodiment of a pneumatic radial tire obtained by a manufacturing method of the present invention.

FIG. 2 is a cross-sectional view showing the form of both ends when a carcass material is spliced according to the present invention.

FIG. 3 is a cross-sectional view showing the form of both ends when a carcass material is spliced according to the present invention.

FIG. 4 is a perspective view illustrating a method of winding a carcass material around a fast forming drum according to an embodiment of the present invention.

FIG. 5 is a perspective view illustrating a situation in which a carcass material is put on a first molding drum according to another embodiment of the present invention.

FIG. 6 is an axial cross-sectional view showing a state in which a tubular laminate is formed on the first molding drum.

[Explanation of symbols]

 1 Tread Part 2 Sidewall Part 3 Bead Core 4 Carcass Layer 4a Carcass Material 5 Belt Layer 6 Reinforcement Cord 7 Cavity 8 Sheet 9 First Molding Drum 10 Inner Liner

Claims (1)

[Claims] 1. A method of manufacturing a pneumatic radial tire in which a plurality of reinforcing cords are arranged side by side and reinforced to form a carcass layer by splicing both ends of a rubberized carcass material into a lap shape, A method for manufacturing a pneumatic radial tire, in which a reinforcing cord is pulled out from one of the ends of the carcass material before being spliced, and then the ends are spliced into a lap shape.