JP2004345537A - Bead core and pneumatic radial tire using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bead core with high quality capable of being manufactured at low cost, and a pneumatic radial tire using the bead core. <P>SOLUTION: A thread 22 is wound about a circumferential partial section so as to include one end 21a and the other end 21b of a bead wire 21. At this time, the thread 22 is wound so that one end 22a of the thread 22 is sandwiched between the thread 22 and a bead wire bundle 30 and the other end 22b of the thread 22 is directed to be wound and fastened by a rotating force acting on the thread 22 (arrow A direction) during vulcanization of a raw tire. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bead core and a pneumatic radial tire using the same.
[0002]
[Prior art]
Generally, as a bead core of a pneumatic radial tire, a bead core manufactured by continuously winding a single bead wire a plurality of times is known (for example, see Patent Document 1). In this case, as shown in FIG. 5, the bead wire 103 is wound so that the one end 103a and the other end 103b of the bead wire 103 overlap, and the yarn 104 is wound around a part of the bead wire bundle 200 including these. , So that both ends 103a, 103b of the bead wire 103 do not jump up.
[0003]
Now, as shown in FIG. 4, when vulcanizing a green tire, a pressure P is applied to the inside of the green tire in a vulcanization mold, and a bead portion 100 is formed as shown by an arrow Z. The spacing between them is reduced. Then, at the time of this vulcanization, the body ply 101 is moved by the pressure P and a synergistic action due to the narrowing of the interval between the bead portions 100. That is, a portion 101a of the body ply 101 on the tire cavity side of the bead portion 100 is moved in a direction toward the tread (the direction of arrow X), and an outer (returned side) portion 101b is a portion on the tire cavity side. It is moved in the opposite direction (arrow Y direction) from 101a. Accordingly, a rotational force acts on the entire bead core 105 as the body ply 101 moves.
[0004]
For this reason, as shown in FIG. 5, the winding directions of both ends 104a and 104b of the yarn 104 are always opposite to each other. For this reason, when the yarn 104 is wound in either the right-handed direction or the left-handed direction, one of the two end portions 104a and 104b of the yarn 104 is tightened by the action of the rotational force, while the other is unwound. It is. Therefore, there is a fear that the winding of the yarn 104 is unwound at one end of both ends 104a and 104b of the yarn 104, and that one of the one end 103a and the other end 103b of the bead wire 103 is likely to jump up. there were.
[0005]
For this reason, conventionally, the yarn 104 is extraly wound around the bead wire bundle 200 in anticipation of the one end portion 104a or the other end portion 104b of the yarn 104 being unwound by the action of the rotational force.
[0006]
[Patent Document 1]
JP 2000-355056 A (Pages 2-4, FIG. 9)
[0007]
[Problems to be solved by the invention]
Then, if the yarn 104 is wound around the bead wire bundle 200 excessively, an extra operation time is required and the yarn 104 is also consumed excessively, so that there is a problem that the manufacturing cost of the bead core 105 increases. . Nevertheless, even if the yarn 104 is excessively wound around the bead wire bundle 200, the risk that the one end 104a or the other end 104b of the yarn 104 is unwound by the action of the rotational force cannot be eliminated.
[0008]
The present invention has been made by paying attention to the problems existing in such a conventional technique. An object of the present invention is to provide a bead core that can be manufactured at low cost and has higher quality and a pneumatic radial tire using the same.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the invention of claim 1, in a bead core in which a yarn is wound around a part of a circumferential direction so as to include one end and the other end of the bead wire, one end of the yarn is The other end of the yarn is wound between the yarn and the bead wire bundle so that the other end of the yarn is wound in a direction in which the yarn is tightened by a rotational force acting on the yarn during vulcanization of a green tire. Is what you do.
[0010]
Therefore, even if a rotational force acts on the yarn as the body ply moves during vulcanization of the green tire, one end of the yarn is fixed between the yarn and the bead wire bundle, and the other end is Since the yarn is tightened by the action of the force, it is possible to eliminate the possibility that both ends of the yarn are unwound by the action of the rotational force. For this reason, both ends of the bead wire can be reliably held down by the yarn, and the fear that one of the one end and the other end of the bead wire jumps up can be eliminated. For this reason, a higher quality bead core can be obtained. In addition, since there is no possibility that both ends of the yarn are unwound, there is no need to extraly wind the yarn around the bead wire bundle. This eliminates the need for extra yarn to wind the yarn around the bead wire bundle, and eliminates the need for extra time to wind the yarn around the bead wire bundle, so that the bead core can be manufactured at low cost.
[0011]
According to a second aspect of the present invention, in the first aspect, the yarn is made of a heat-shrinkable synthetic fiber.
Accordingly, the yarn shrinks due to the heating during vulcanization of the green tire, and the shrinkage of the yarn can more strongly hold both end portions of the bead wire.
[0012]
According to the third aspect of the present invention, in the first or second aspect, the length of the overlapping portion between one end and the other end of the bead wire is within a range of 10 to 20 mm, and the winding portion of the yarn. The point is that the distance between one end of the bead wire and one end of the bead wire which is closer thereto is within the range of 20 to 60 mm.
[0013]
Therefore, the amount of yarn to be wound around the bead wire bundle can be reduced as compared with the related art, so that the yarn to be wound around the bead wire bundle can be saved and the operation time for winding the yarn around the bead wire bundle can be shortened.
[0014]
In the invention described in claim 4, in any one of claims 1 to 3, the length of one end of the yarn sandwiched between the yarn and the bead wire bundle is the winding pitch of the yarn. The gist of the invention is that the length is longer than one-half of the winding width of the yarn.
[0015]
Therefore, the width of the length of one end of the yarn sandwiched between the yarn and the bead wire bundle can be increased, and the dimensional management thereof is facilitated.
According to a fifth aspect of the present invention, there is provided a pneumatic radial tire using the bead core according to any one of the first to fourth aspects.
[0016]
Therefore, it can be manufactured at low cost, and by using a higher quality bead core, the manufacturing cost of the pneumatic radial tire can be reduced and the quality can be further improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
As shown in FIG. 1, in a pneumatic radial tire 11 of this embodiment, 12 indicates a tread portion, 13 indicates a sidewall portion, 14 indicates a bead portion, and 16 indicates a body ply. Reference numeral 17 denotes two steel cord belts, reference numeral 18 denotes a cap belt on the belt 17, and reference numeral 19 denotes a shoulder ply. Reference numeral 15 denotes a rim of the vehicle, and 15a denotes a rim flange.
[0018]
As shown in FIGS. 1 and 2, a bead core 20 is embedded in each of the bead portions 14, and the bead core 20 is formed by continuously winding a single bead wire 21 whose periphery is covered with rubber. A bead wire bundle 30 having a substantially hexagonal cross section is formed. Also, a bead filler 23 made of hard rubber and having a substantially triangular cross section is attached to the outer diameter side of the tire of each bead core 20. Then, both ends of the body ply 16 are inverted along the outer peripheral surfaces of the bead core 20 and the bead filler 23, and the bead core 20 is covered by the body ply 16. FIG. 2 shows the movement of the bead portion 14 at the time of vulcanization, in which only the bead portion 14, the body ply 16, and the bead filler 23 are drawn. , Tread and the like.
[0019]
Then, as shown in FIG. 3, a heat-shrinkable material such as vinylon is applied to a part of the circumferential direction of the bead wire bundle 30 so as to include an overlapping portion D of one end 21 a and the other end 21 b of the rubber-coated bead wire 21. The yarn 22 made of the synthetic fiber is wound at a predetermined winding pitch. Therefore, the bead core 20 is constituted by the bead wire 21 and the thread 22 coated with rubber.
[0020]
One end 22a of the yarn 22 is sandwiched between the yarn 22 and the bead wire bundle 30, and the other end 22b of the yarn 22 is tightened by a rotational force acting on the yarn 22 during vulcanization of a green tire. It is wound so that it may become a direction (direction of arrow A). In this case, the length of one end 22a of the yarn 22 sandwiched between the yarn 22 and the bead wire bundle 30 is longer than the winding pitch of the yarn 22 and is a half of the winding width E of the yarn 22. The length is shorter than one.
[0021]
Further, the length of the overlapping portion D is preferably within a range of 10 to 20 mm. In addition, the distance F between one end of the winding portion 40 of the yarn 22 and one end of the bead wire 21 which is closer thereto is preferably in the range of 20 to 60 mm.
[0022]
Now, as shown in FIGS. 1 and 2, when vulcanizing a green tire, a pressure P is applied to the inside of the green tire in a vulcanization mold, and as shown by an arrow C, a bead portion 14 is formed. The spacing between them is reduced. When the green tire is vulcanized, the body ply 16 is moved by the pressure P and the synergistic action of the bead portion 14 being narrowed. That is, the portion 16a on the tire lumen side of the body ply 16 in the bead portion 14 is moved in the direction toward the tread (the direction of arrow A), and the outer (returned side) portion 16b is moved toward the tire lumen side. 16a is moved in the opposite direction (the direction of arrow B). Therefore, a rotational force acts on the entire bead core 20 as the body ply 16 moves.
[0023]
However, in this case, one end 22a of the yarn 22 is fixed between the yarn 22 and the bead wire bundle 30, and the other end 22b is tightened by the action of the rotational force. However, there is no possibility of being rewound by this rotational force.
[0024]
According to the embodiment described in detail above, the following effects are exhibited.
-It is possible to eliminate the possibility that the yarn 22 is unwound during vulcanization of a green tire. For this reason, both ends 21a and 21b of the bead wire 21 can be reliably held down by the yarn 22, and the fear that one of the one end 21a and the other end 21b of the bead wire 21 jumps up can be eliminated. For this reason, a higher quality bead core can be obtained. In addition, since there is no possibility that both ends 22a and 22b of the yarn 22 are unwound, there is no need to extraly wind the yarn 22 around the bead wire bundle 30. Therefore, the yarn 22 for winding the yarn 22 extra around the bead wire bundle 30 becomes unnecessary, and the operation time for extra winding the yarn 22 around the bead wire bundle 30 becomes unnecessary, so that the bead core 20 is manufactured at low cost. be able to.
[0025]
Since the yarn 22 is made of heat-shrinkable synthetic fiber, it shrinks by heating during vulcanization of the green tire. Due to the contraction of the yarn 22, both end portions 21a and 21b of the bead wire 21 can be pressed more strongly. For this reason, it is possible to eliminate the fear that one of the one end 21a and the other end 21b of the bead wire 21 will jump up, so that a higher quality bead core can be obtained.
[0026]
The winding amount of the yarn 22 to be wound around the bead wire bundle 30 is smaller than before, and the yarn 22 to be wound around the bead wire bundle 30 can be saved, and the operation time for winding the yarn 22 around the bead wire bundle 30 can be shortened. Can be.
[0027]
The length of one end 22a of the yarn 22 sandwiched between the yarn 22 and the bead wire bundle 30 is longer than the winding pitch of the yarn 22 and is smaller than half the winding width E of the yarn 22. Are also short. For this reason, the width of the length of one end 22a of the yarn 22 sandwiched between the yarn 22 and the bead wire bundle can be increased, and the dimensional management thereof is facilitated.
[0028]
(Example of change)
The above-described embodiment may be modified as follows.
The thread 22 is a metal wire that is thinner than the bead wire 21 and whose surface is plated.
[0029]
【The invention's effect】
As described in detail above, the present invention can be manufactured at low cost, and can provide a higher quality bead core and a pneumatic radial tire using the same.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a pneumatic radial tire according to an embodiment.
FIG. 2 is an enlarged simplified cross-sectional view of a bead portion of the tire of FIG.
FIG. 3 is a perspective view of the bead core of FIG. 2;
FIG. 4 is an enlarged simplified cross-sectional view of a bead portion of a conventional pneumatic radial tire.
FIG. 5 is a perspective view of a conventional bead core.
[Explanation of symbols]
11 ... radial tire, 14 ... bead part, 16 ... body ply, 20 ... bead core, 21 ... bead wire constituting bead core, 21a ... one end of bead wire, 21b ... other end of bead wire, 22 ... thread constituting bead core, 22a: one end of the yarn, 22b: the other end of the yarn, 30: bead wire bundle, 40: the winding portion of the yarn, D: overlapping portion, E: winding width, F: distance.

Claims (5)

In a bead core in which the yarn is wound around a part of the circumferential direction so as to include one end and the other end of the bead wire,
One end of the yarn is sandwiched between the yarn and a bead wire bundle, and the other end of the yarn is wound in a direction in which the yarn is tightened by a rotational force acting on the yarn during vulcanization of a green tire. A bead core characterized by: The bead core according to claim 1, wherein the yarn is made of a heat-shrinkable synthetic fiber. The length of the overlapping portion between the one end and the other end of the bead wire is in the range of 10 to 20 mm, and the length between the one end of the wound portion of the yarn and one end of the bead wire closer thereto is set. The bead core according to claim 1, wherein the distance is in a range of 20 to 60 mm. The length of one end of the yarn sandwiched between the yarn and the bead wire bundle is longer than the winding pitch of the yarn and shorter than one half of the winding width of the yarn. Item 4. The bead core according to any one of items 1 to 3. A pneumatic radial tire using the bead core according to claim 1.

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