JPH0679806A - Bead wire for bead core used for producing pneumatic tire and pneumatic tire using it - Google Patents

Abstract

PURPOSE:To prevent upper layer side bead wires from falling in between lower layer side bead wires, when a single bead wire is wound into a plurality of rows by a plurality of layers. CONSTITUTION:Bead wire is produced by covering coating rubber 2 round strip wire 1. In this case, the crosssectional profile of the coating rubber 2 is irregular one consisting of a circular arc 3 and four projecting parts 4 locating at angular intervals of 90 deg. to the peripheral direction of the circular arc 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bead wire for a bead core used for manufacturing a pneumatic tire and a pneumatic tire using the same, and more particularly, to a cross-sectional outer contour of a coating rubber covering a strip wire. By devising the shape, a single bead wire is wound in a plurality of rows and a plurality of stages to produce a bead core, which results in a stable overlapping posture of the bead wires.

[0002]

2. Description of the Related Art As a conventional bead core used for manufacturing a pneumatic tire, a plurality of strip wires arranged in parallel with each other are integrally covered with a rubber to form a ribbon-shaped bead wire, which has a required number of steps. It is widely used by stacking and winding. However, in such a bead core, since the starting end portion and the terminating end portion of each bead wire overlap over the entire width of the bead core, the uniformity of the tire is lowered and the fitting surface pressure at the time of tire rim fitting is reduced. However, there were problems such as unevenness on the circumference. Therefore, in order to solve these problems with the recent increase in accuracy required for tires, one bead wire is spirally wound in multiple rows under a certain radius, and this is repeated over the required multiple terms. It has been proposed that the bead core be used as the bead core so that the bead wire has only one overlapping portion between the start end portion and the end portion.

[0003]

However, in the case of manufacturing such a bead core using a conventional bead wire whose coating rubber has a circular outer cross-sectional outer shape, one bead wire is wound. Since the contact areas of the coating rubbers in the stacking direction of the bead wires are small at the time of stacking, the bead wires wound on the lower stage side and adjacent to each other when the upper bead wire is wound. A bead core formed by sliding or falling into the groove between the two has a cross-sectional shape like a so-called hexagonal bead, and its side wall surface does not become a straight state.Therefore, a molding method without a bead lock structure is used. During application, the result of combination becomes unstable in the process of combining the bead and the carcass ply cord. , Uniformity in the tire there is a problem that not stable. The present invention is to solve this problem, slipping off the bead wire during the formation of the bead core, sufficiently preventing the fall,
Provided is a bead wire for a bead core used in the production of a pneumatic tire, which can always have a cross-sectional shape of a bead core as expected.

[0004]

A bead wire for a bead core used in the production of a pneumatic tire according to the present invention comprises a strip wire covered with a coating rubber, and the coating rubber may be any of the coating rubber. The outer contour shape of the cross-section at the position is an arc and a deformed shape composed of four protrusions located at 90 ° angular intervals in the circumferential direction of the arc, and more preferably here. The respective projections have an arc or a shape similar to that of an arc inscribed on two sides of each corner of a square circumscribing the arc.

In another strip wire, the outer contour shape of the cross-section of the coated rubber is formed by an arc and chord portions which are located in at least two positions opposed to each other in the diametrical direction of the arc and are parallel to each other, for example, a long wire. Have a circular shape.

In still another strip wire, the cross-sectional outer contour shape of the coating rubber is elliptical, and more preferably, the cross-section outer contour shape is the elliptical portion and each corner of the rectangle circumscribing the elliptical portion. , And the projections inscribed on its two sides are combined to form an irregular shape. Further, the outer contour shape of the cross section of the strip wire coating rubber is made into a polygonal shape whose opposite sides are parallel to each other.

In the pneumatic tire of the present invention, a bead core formed by winding a plurality of rows of bead wires having any one of the above-mentioned cross-sectional shapes is embedded in the bead portion of the tire.

[0008]

In the bead wire of the present invention, the outer contour shape of the cross-section of the coating rubber is an irregular shape consisting of an arc and four protrusions. The coating rubber of the bead wire will be in mutual contact with the arc-shaped portion and the total of the respective protrusions, at three points, and the bead wire on the upper stage side is supported sufficiently stably by the bead wire on the lower stage side. As in the prior art, when the upper bead wire is wound, it can be effectively prevented from sliding down between the lower bead wires.

Further, the outer contour of the cross-section of the coating rubber is, for example, an elliptical bead wire, which is composed of an arc and chord portions which are located in opposition to the diametrical direction of the arc and are parallel to each other. Then, since the upper side coating rubber and the lower side coating rubber come into surface contact with each other with a sufficient area when they are wound, again, stable support of the upper side bead wire is carried out and the crossing of the bead core is performed. The collapse of the surface shape can be sufficiently prevented.

In the coating rubber in which the cross-sectional outer contour shape of the coating rubber is elliptical, each of the coating rubbers of the upper and lower bead wires is elastically deformed by itself, and the conventional circular cross-section outer contour shape is obtained. Compared with the coating rubber that has a surface contact with a larger area, this also enables stable support of the upper bead wire, and between the upper bead wire and the lower bead wire. It is possible to effectively prevent the slip and fall.

This is particularly remarkable when the outer contour shape of the coating rubber is an irregular shape in which an elliptical portion and a protrusion are combined, and according to this, in addition to the above, Since the respective protrusions of the coating rubber of (1) also contact each other, the stability of the support of the upper bead wire can be further enhanced. Furthermore, in the present invention, when the cross-sectional outer contour shape of the coating rubber is a polygonal shape in which the opposite sides are parallel to each other, a support having substantially the same support as when the outer contour shape is an elliptical shape is provided. Can bring stability.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a transverse cross-sectional view illustrating a state in which bead wires are stacked in two stages in a direction corresponding to the tire radial direction. Here, the outer contour shape of the coating rubber 2 coated around the strip wire 1 is defined by an arc 3 and four protrusions 4 located at 90 ° angular intervals in the circumferential direction of the arc 3. It has a different shape. Each protrusion 4 linearly extends in the axial direction of the strip wire 1 to form a protrusion.

Here, the bead wire is formed so that each protrusion 4 is inscribed in two corners of a square which is circumscribed in an arc portion and which is shown by an imaginary line in the figure. It is preferable to realize stable support of. Further, preferably, by forming the contour arc of the protrusion 4 or other curved shape, it is possible to facilitate the processing of the insulation die used when coating the bead wire with rubber.

According to such a bead wire, when the bead core is formed by winding the bead wire, the contact areas of the bead wires adjacent to each other in the vertical and horizontal directions, especially in the vertical direction are increased, and the bead wire on the upper stage side is increased. But,
Since it is stably supported by the lower bead wire, it is possible to effectively prevent sliding of the upper bead wire between the lower bead wires, and as a result, the desired cross-sectional shape. It is possible to always accurately manufacture a bead core having

FIG. 2 is a cross-sectional view showing another embodiment of the present invention, in which the outer contour shape of the coating rubber 2 covering the strip wire 1 is an arc 5 and the diameter of the arc 5. It has a substantially elliptical shape composed of two chord portions 6 which are located at two positions opposed to each other and which are parallel to each other. According to this, since the bead wires vertically adjacent to each other can be supported sufficiently stably by the surface contact at the string portion 6, as in the prior art,
It is possible to almost surely prevent the upper bead wire from sliding down between the lower bead wires, and to make the cross-section side wall of the bead core substantially vertical.

FIG. 3 is a cross-sectional view showing still another embodiment of the present invention. Here, the outer contour shape of the coating rubber 2 covering the strip wire 1 is in a direction corresponding to the width direction of the tire. The elliptical shape with the major axis extended. According to this embodiment, in the bead wires which are vertically adjacent to each other, the mutual contact area of the coating rubbers 2 is made wider than that of the conventional technique, so that the stability of the support can be enhanced.

FIG. 4 is a transverse sectional view showing another embodiment.
Here, the outer contour shape of the coated rubber is changed to the elliptical portion
And each of the corners of the rectangle 8 circumscribing the elliptical portion 7 is combined with four protrusions 9 inscribed on two sides of the rectangle 8 to form an irregular shape. In this bead wire, since the basic ring shape of the coating rubber is an elliptical shape, it is possible to bring about the same operational effect as the above-described example, and moreover, because of the presence of the protrusion 9, the bead wire of the upper stage side wire The stability of support can be further enhanced. Therefore,
Also in this case, slipping and rolling down of the bead wire during winding can be effectively prevented.

FIG. 5 is a cross-sectional view showing still another embodiment, in which the coating rubber 2 covering the strip wire 1 has an outer contour shape of a polygonal shape in which opposing sides are parallel to each other, here, a square shape. It was done. In this bead wire, the upper and lower wires come into full surface contact with each other when it is wound, and the stability of the support of the upper bead wire is further enhanced.

[0019]

As is apparent from the above description, according to the present invention, when forming a bead core by winding one bead wire in a plurality of rows and a plurality of stages,
The lower bead wire supports the upper bead wire sufficiently stably to prevent the upper bead wire from falling between the lower bead wires, and the cross-sectional shape of the bead wire is always expected. It can be exactly what you did.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing still another embodiment of the present invention.

[Explanation of symbols]

 1 Strip wire 2 Coating rubber 3,5 Arc 4,9 Projection 6 String part 7 Elliptical part 8 Circumscribed rectangle

Claims (6)

[Claims] 1. A bead wire comprising a strip wire and a coating rubber covering the circumference of the strip wire, wherein the cross-sectional outer contour shape of the coating rubber is an arc.
A bead wire for a bead core used in the manufacture of a pneumatic tire, which has a deformed shape including four protrusions located at 90 ° angular intervals in the circumferential direction of the arc. 2. A bead wire comprising a strip wire and a coating rubber covering the circumference of the strip wire, wherein the cross-sectional outer contour shape of the coating rubber is an arc.
A bead wire for a bead core used in the manufacture of a pneumatic tire, characterized in that the bead wire is formed in at least two positions that oppose each other in the diametrical direction of the circular arc, and has a chord portion that is mutually parallel. 3. A bead wire comprising a strip wire and a coating rubber covering the periphery of the strip wire. The coating rubber is used for manufacturing a pneumatic tire, wherein an outer contour of a cross section of the coating rubber is an elliptical shape. Bead wire for bead core. 4. A bead wire formed by covering a strip wire with a coating rubber, the cross-section outer contour shape of the coating rubber being an elliptical portion and each corner of a rectangle circumscribing the elliptical portion, A bead wire for a bead core used for manufacturing a pneumatic tire, which has a deformed shape in which projections inscribed on two sides thereof are combined. 5. A bead wire comprising a strip wire covered with a coating rubber, wherein the coating rubber has a cross-sectional outer contour shape in a polygonal shape in which opposite sides are parallel to each other. To do
Bead wire for bead cores used for manufacturing pneumatic tires. 6. A pneumatic tire in which a bead core formed by winding a plurality of rows of the bead wire according to any one of claims 1 to 5 is embedded in a bead portion of a tire.