KR100917757B1 - Joint method of body ply in pneumatic tire - Google Patents

Abstract

The present invention relates to a body ply bonding method of a pneumatic tire, and more particularly, to bulge tires by appropriately forming and adhering overlapping both end thicknesses and shapes of the body ply in order to minimize the thickness variation of the overlap part when the body plies are bonded. The present invention relates to a body ply bonding method capable of suppressing dent defects.

According to the present invention, the body fly joint is optimally designed so that the stress concentration can be effectively distributed, thereby improving the uniformity and reducing the defective points on the joint such as bulges and dents, thereby improving the durability of the tire.

Tires, Body Fly, Carcass, Durability, Bonding, Overlap

Description

Body fly bonding method of pneumatic tire {JOINT METHOD OF BODY PLY IN PNEUMATIC TIRE}

The present invention relates to a body ply bonding method of a pneumatic tire, and more particularly, in order to minimize the change in thickness of the overlap part when the body ply is bonded, by forming and bonding the thickness and shape of both overlapping ends of the body ply properly, The present invention relates to a method for joining a body fly that can suppress bulge and dent defects.

In general, tires are molded by assembling several semi-finished products, such as body plies (also called carcasses), treads, beads, etc., on a forming drum, which necessarily result in forming and cutting joints between these semi-finished products. On the other hand, the body fly is a member for maintaining the internal pressure, the tension due to the internal pressure in all directions acts to maintain the tension is mainly provided with a cord made of a material such as nylon, polyester (polyester), rayon (rayon) The plurality of fabric cords are arranged at regular intervals and coated with a thin rubber sheet up and down to form a coded paper.

In the tire according to the prior art, as shown in FIG. 1, the inner body liner 10 and the secondary body fly 20 are extruded into respective semi-finished products, and the inner liner is formed on the forming drum 1 during the primary forming process. After the (not shown) is coupled to the upper surface in order to form the molding. At this time, the inner liner and the first and second body fly joints are formed in the tire width direction, respectively, and FIG. 2 shows a state in which one end of the body ply 10 is coupled to each other on the forming drum. When overlapping and joining the conventional body ply like this, as shown in the drawing, the overlap portion 15 becomes thicker than other portions.

As such, when the overlap portion having a thicker thickness is formed at the junction of the body fly, stress is concentrated on the portion, and the uniformity of the tire is reduced, thereby reducing durability.

In order to alleviate this problem, as shown in Fig. 3, when the two body plies are overlapped and bonded, the overlap parts are molded in the circumferential direction of the tire. That is, over the entire circumference of the tire, one overlap portion 15 of the primary body ply 10 'occurs, and one overlap portion 25 of the secondary body ply 20' also occurs.

However, even in this case, when the amount of overlap of the body fly joint is insufficient, a bulge defect occurs in which the joint rubber swells when the tire is inflated. On the contrary, when the amount of overlap of the joint is excessive, the joint is relatively less swollen than the peripheral portion. There was a problem that rising dent defects occur.

The present invention has been made to solve the above problems, by minimizing the thickness change in the joint of the body ply to prevent bulge, dent defects on the molded pneumatic tire single piece, body ply that can improve the uniformity and durability The purpose is to provide a joining method.

Body ply bonding method of the pneumatic tire according to the present invention devised to achieve the above object, in the method of overlapping the body ply of the pneumatic tire on the forming drum, the body ply, both ends of the overlap Each having a reduced thickness, it is characterized in that the bonding by forming and pressing so as to face each other when bonding.

In addition, the thickness reduction portion of the body ply, preferably 60 to 70% of the original thickness, the thickness of the fabric cord included in the thickness reduction portion of the body ply, it is to form to 60 to 70% of the original thickness desirable.

In addition, the number of fabric cords included in the thickness reduction portion of the body ply is preferably 4-6.

And when bonding two body plies, it is preferable to shape | mold so that the overlap part of each body ply may be separated from each other without overlapping.

According to the body fly jointing method of pneumatic tires according to the present invention, the body fly joint is optimized and the stress concentration is effectively dispersed, thereby improving the uniformity and reducing the defective points on the joint such as bulges and dents. It has the effect of improving durability.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 4 is a perspective view showing the bonding portion of the body fly according to an embodiment of the present invention. In Figure 4 is shown for the junction of one body fly 10 for the purpose of description, when molding using two body plies as shown in Figure 1 can be applied to the same method of the present invention to each body fly have. In addition, although the primary body ply 10 appears to be made of two flat plates in FIG. 4, since the body plies are bonded on the cylindrical forming drum 1, the body plies 10 joined on the innerliner are also shown. It will be understood that it is molded into a cylinder as a piece.

As shown in the enlarged view of FIG. 4, both ends of the body ply 10 that overlap each other on the forming drum are each provided with a thickness reduction part occupying half of the original thickness on the basis of the thickness after being joined. The reduction portions overlap each other to form an overlap portion 16. In fact, when the body ply before bonding to the forming drum is unfolded on a plane, it is preferable that the cross-sectional shape in the tire circumferential direction is formed so that both ends are point symmetrical.

Since the thickness reducing portions formed at both ends of the body ply formed in the forming drum are joined while pressing at the time of joining, the thickness is reduced after joining. Therefore, it is preferable that the thickness reduction portion of the body ply prepared in advance in consideration of the expected thickness reduction is formed at 60 to 70% of the original thickness. By forming in this way, when the overlap part of a body fly is crimped | bonded and bonded, an overlap part can also be formed so that a continuous plane may be formed in the adjacent surface. As a result, the traces of adhesion appearing in the overlapping portion 16 are only in the adhesive line 17 formed in the width direction of the body ply 10. Furthermore, if the adhesive lines 17 also form inclined surfaces at the ends of both thickness reducing portions and correspond to each other, they may be blurred or not visible at the time of bonding depending on their dimensions and molding precision.

In addition, the thickness of the fabric cords 12 included in the thickness reduction portion of the body ply, it is preferable to form 60 to 70% of the original thickness of the fabric cords 11 in the other portion. Fabric cords 12 contained in the thickness reduction portion of the body ply is also compressed to be reduced when the thickness is reduced, so as to form a thickness of 60 ~ 70% of the original thickness as the thickness reduction portion.

In addition, the number of fabric cords 12 included in the thickness reduction part of the body ply is preferably 4-6. The overlap amount of the joint is set in consideration of bulging defects and dent defects, and defines a dimension range overlapping with the number of fabric cords. In addition, the fabric cord is most preferably in terms of bulge, dent defect and durability to be formed to cross each other at the overlap portion.

The thickness of the body fly used in the body fly bonding method of the present invention is that of 1.14mm ~ 1.37mm depending on the material. In addition, since the thickness reduction portions are formed at both ends of the body ply, the first and second body plies must be cut in advance at the joint formation position and loaded into a roll by the required length on the molding specification. The circumferential length of each of the innerliner, the primary body fly 10 and the secondary body fly 20 can be calculated by the following equation.

Inner Liner Length = (Drum Diameter + Inner Liner Thickness) × π + Inner Liner Length

Primary body ply length = (Drum diameter + innerliner thickness × 2 + body ply thickness) × π + body ply overlap length

Length of secondary body fly = (Drum diameter + inner liner thickness × 2 + body fly thickness × 3) × π + body fly length

As such, since the primary body ply and the secondary body ply formed by pre-cutting the body ply are used in the primary molding, a separate cutting process is not required, thereby improving workability and reducing molding time.

5 is a partial cross-sectional view of the primary body fly 10 and the secondary body fly 20 bonded according to the bonding method of the present invention. Here, the fabric cords 11, 12, etc. are omitted and schematically illustrated. And, it will be understood that there is no overlap portion in the remaining omitted portions circumferentially other than the illustrated portion. The overlap portion 16 of the primary body ply 10 and the overlap portion 16 of the secondary body ply 20 are formed so as to disperse the stress concentration to the adhesive portion by having a predetermined distance without overlapping each other. . In addition, in contrast to FIG. 3 according to the prior art, the body fly can be formed to have a uniform thickness throughout the circumference.

Although the preferred embodiments of the present invention have been described above, the scope of the present invention is not limited to such specific embodiments, and a person of ordinary skill in the art is properly within the scope described in the claims of the present invention. Changes will be possible.

1 is a schematic diagram illustrating molding a body ply of a pneumatic tire in a forming drum in general.

Figure 2 is a perspective view showing the joint portion of the body fly according to the prior art.

Figure 3 is a schematic cross-sectional view showing a state in which two body plies are joined by the prior art.

Figure 4 is a perspective view showing the bonding portion of the body fly according to the present invention.

5 is a schematic cross-sectional view showing a state in which two body plies are joined according to the present invention.

<Description of the symbols for the main parts of the drawings>

1: Molding drum

10: primary body fly

11: fabric cord

12: fabric cord of overlap part

13 slope portion

15: thick overlap

16: overlap part

17: seam

20: secondary body fly

25: thick overlap

26: overlap of the secondary body fly

Claims (5)

In the method of overlapping the body ply of the pneumatic tire on the forming drum, The body ply, each having a thickness reducing portion at each of the overlapping ends, formed by bonding to face each other at the time of bonding, bonding by The thickness reduction portion of the body ply, is formed of 60 to 70% of the original thickness, The thickness of the fabric cords included in the thickness reduction portion of the body ply, body fly bonding method, characterized in that formed to 60 to 70% of the original thickness. delete delete The method of claim 1, Body fly bonding method characterized in that the number of fabric cords contained in the thickness reduction portion of the body ply is 4-6. The method according to claim 1 or 4, In the case of bonding two body plies, the overlapping portions of the body plies are molded so as not to overlap with each other and to be separated from each other.

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