JP6133556B2 - Cable bead and pneumatic tire using the same - Google Patents

Description

  The present invention relates to a cable bead and a pneumatic tire using the cable bead (hereinafter, also simply referred to as “tire”). Specifically, when used as a bead core of a pneumatic tire for a passenger car and a pneumatic tire for a motorcycle, The present invention relates to a cable bead that can improve grip feeling, stability, and turning performance more than a tire, and a pneumatic tire using the cable bead.

  In recent years, in a pneumatic tire, for the purpose of improving steering stability, it is a common practice to increase the rigidity of a tire bead portion. Conventionally, for example, a bead in which a plurality of sheath layers formed by winding a plurality of steel filaments around a core serving as a central structure, which exhibits high rigidity against twisting in a bead portion, a so-called cable bead is used. The arrangement | positioning etc. which are arrange | positioned are employ | adopted.

  As a technique related to the improvement of the cable bead, for example, in Patent Document 1, a lightweight, inexpensive, and formable cable bead in which the material of the core filament, the wire diameter of the core filament, and the wire diameter of the sheath filament are predetermined. Has been proposed. Patent Document 2 proposes a method for manufacturing a cable bead that can improve the gripping force, turning performance, and responsiveness while maintaining stability.

JP 2006-44643 A Japanese Patent Laid-Open No. 7-68662

  Patent Document 1 is a technique for reducing the weight of a cable bead by reducing the diameter of the core filament. On the other hand, when a cable bead is used as a bead core of a pneumatic tire for a motorcycle, the core filament of the cable bead is used. It is known that the larger the diameter, the better the cornering stability. However, when the diameter of the core filament of the cable bead is increased, the swirlability is lowered, and it is difficult to achieve both stability and swirlability. Further, even with the cable bead described in Patent Document 2, what characteristics contribute to the feeling performance such as gripping force, turning performance and responsiveness has not been sufficiently studied, and further improvements are made. There was room for.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cable bead capable of improving grip feeling, stability and turning performance as compared with conventional tires when used as a bead core for a pneumatic tire for a passenger car and a pneumatic tire for a motorcycle. It is to provide a pneumatic tire using the tire.

  As a result of intensive studies to solve the above problems, the present inventor has determined that the rigidity of the cable bead in the same plane direction as the cable bead (in-plane rigidity) is Si and the rigidity in the direction orthogonal to the same plane direction of the cable bead ( When the out-of-plane rigidity (So) is set to So, the in-plane rigidity Si and the out-of-plane rigidity So satisfy the predetermined relationship to find that the above problems can be solved, and the present invention has been completed. .

That is, the cable bead of the present invention includes a core formed in an annular shape by abutting and welding both ends of a core filament, and a sheath in which a plurality of sheath filaments are spirally wound around the core. In the cable bead
When the rigidity with respect to the force in the same plane direction as the cable bead is Si (mN / mm), and the rigidity with respect to the force in the direction orthogonal to the same plane direction of the cable bead is So (mN / mm), the Si and the above So is the following formula (1),
0.45 ≦ So / Si ≦ 0.60 (1)
It is characterized by satisfying the relationship represented by

In the cable bead of the present invention, when the wire diameter of the core filament is dc (mm) and the wire diameter of the sheath filament is ds (mm), the dc and the ds are represented by the following formula (2),
0.30 ≦ ds / dc ≦ 1.00 (2)
It is preferable to satisfy the relationship represented by these. Moreover, in the cable bead of this invention, it is preferable that the frequency | count of winding of the sheath filament around the said core is 7-10 (turns / circumference).

The pneumatic tire of the present invention is a pneumatic tire provided with a pair of bead portions respectively formed on the inner periphery of a pair of sidewall portions connecting both ends of the tread portion.
The cable bead according to the present invention is embedded in the bead portion.

  According to the present invention, when used as a bead core of a pneumatic tire for a passenger car and a pneumatic tire for a motorcycle, a cable bead that can improve grip feeling, stability, and turning performance as compared with a conventional tire, and a cable bead are used. A pneumatic tire can be provided.

It is sectional drawing of the cable bead which concerns on one suitable embodiment of this invention. It is explanatory drawing which shows the direction orthogonal to the same plane direction and the same plane direction of a cable bead. It is explanatory drawing for demonstrating the coil diameter of a core and the coil diameter of a sheath filament. 1 is a one-side sectional view in the tire width direction of a pneumatic tire for a passenger car according to a preferred embodiment of the pneumatic tire of the present invention. FIG. 6 is a one-side sectional view in the tire width direction of a pneumatic tire for a motorcycle according to another preferred embodiment of the present invention. It is explanatory drawing of the measuring method of the in-plane rigidity and out-of-plane rigidity of a cable bead.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of a cable bead according to a preferred embodiment of the present invention. In the cable bead 1 of the present invention, both ends of a core filament 2 are butted and welded to form an annular core, and a plurality (seven in the illustrated example) of sheath filaments 3 are spirally wound around the core. A sheath.

Drawing 2 is an explanatory view showing the direction which intersects perpendicularly to the same plane direction and the same plane direction of a cable bead. In the cable bead 1 of the present invention, the rigidity in the same plane direction as the cable bead 1 (direction of arrow A in the figure) is Si (in-plane rigidity Si), and the direction orthogonal to the same plane direction of the cable bead 1 (in the figure). When the rigidity in the direction of arrow B) is So (out-of-plane rigidity So), the in-plane rigidity Si and the out-of-plane rigidity So are expressed by the following formula (1),
0.30 ≦ So / Si ≦ 0.70 (1)
Satisfies the relationship expressed by By using a cable bead that satisfies the relationship expressed by the above formula (1) as a bead core of a pneumatic tire for a passenger car or an air retire for a motorcycle, grip feeling, stability, and turning performance can be improved.

That is, by setting the out-of-plane rigidity So of the cable bead 1 to 70% or less of the in-plane rigidity Si, the contact area of the tire during cornering can be increased, and the grip feeling, turning performance and stability can be improved. . Moreover, when the relationship represented by the above formula (1) is satisfied, the rim assembly property when the tire is assembled to the rim is also improved. However, when the out-of-plane rigidity So is less than 30% of the in-plane rigidity Si, the sense of rigidity, cornering performance, responsiveness, and stability during cornering are lowered. In addition, the tire may be easily detached from the rim. Preferably,
0.40 ≦ So / Si ≦ 0.60
More preferably,
0.45 ≦ So / Si ≦ 0.55
It is.

  In order to change the out-of-plane rigidity So of the cable bead 1, the diameters of the core filament 2 and the sheath filament 3 are changed, the coil diameter of the sheath filament 3 is changed, and the number of times the sheath filament 3 is wound around the core is changed. It can be adjusted by changing. The in-plane rigidity Si varies depending on the tire size and application, but again, the diameters of the core filament 2 and the sheath filament 3 are changed, the coil diameter of the sheath filament 3 is changed, and the sheath filament is also changed. It can be adjusted by changing the number of windings around the core No. 3. For example, when the diameter of the core filament 2 or the sheath filament 3 is increased, both the in-plane rigidity Si and the out-of-plane rigidity So increase. However, for example, when the coil diameter of the sheath filament 3 is decreased, only the out-of-plane rigidity So is obtained. descend. Further, by increasing the number of times the sheath filament 3 is wound, the out-of-plane rigidity So can be made larger than the in-plane rigidity Si, and by increasing the diameter ratio between the core filament 2 and the sheath filament 3, the in-plane rigidity Si. It is possible to increase the out-of-plane rigidity So.

In the cable bead 1 of the present invention, when the wire diameter of the core filament 2 is dc and the wire diameter of the sheath filament 3 is ds, dc and ds are expressed by the following formula (2).
0.30 ≦ ds / dc ≦ 1.00 (2)
It is preferable to satisfy the relationship expressed by: If the value of ds / dc is less than 0.3, the sheath filament 3 is difficult to wind around the core. As a result, the arrangement of the sheath filaments 3 is likely to be disturbed, and when the obtained cable bead is placed on a plane, there is a possibility that the cord shape may be deteriorated such that a part of the cord is lifted. On the other hand, if the value of ds / dc exceeds 1.0, it may lead to an increase in tire weight, which is not preferable.

In the cable bead 1 of the present invention, when the coil diameter of the core formed in an annular shape is Dc and the coil diameter of the sheath filament 3 before being wound around the core is Ds, Dc and Ds are expressed by the following formula ( 3),
0.60 ≦ Ds / Dc ≦ 2.00 (3)
It is preferable to satisfy the relationship represented by these. By setting Ds / Dc within the above range, the in-plane rigidity Si and the out-of-plane rigidity So satisfy the relationship represented by the above formula (1), while ensuring the moldability of the cable beads.

  FIG. 3 is an explanatory diagram for explaining the coil diameter Dc of the core and the coil diameter Ds of the sheath filament 3. The cable bead 1 butt welds both ends of the core filament 2 to produce an annular core, and then is wound around a supply reel 4 as shown in FIG. Is manufactured by spirally winding the core around the core. In this example, the diameter of the core formed in an annular shape is the coil diameter Dc of the core, and the winding diameter of the sheath filament 3 spirally formed by being wound around the supply reel 4 is the coil diameter Ds of the sheath filament 3. .

  Furthermore, in the cable bead of the present invention, it is preferable that the number of windings of the sheath filament 3 around the annular core is 7 to 10 (turns / circumference). This is because if the number of windings of the sheath filament 3 is out of the above range, the value of So / Si may not satisfy the relationship represented by the above formula (1).

  In the cable bead 1 of the present invention, it is only important that the in-plane rigidity Si and the out-of-plane rigidity So satisfy the relationship represented by the above formula (1), and the other configurations are not particularly limited. For example, the cable bead shown in FIG. 1 has a single layer sheath, but the cable bead of the present invention may be provided with a plurality of layers. In this case, the number of sheath layers may be appropriately determined depending on the tire size and application of the applied tire. For example, when applied to a pneumatic tire for a passenger car or a pneumatic tire for a motorcycle, it is preferable that the sheath has a single layer as shown in FIG.

  In the cable bead 1 of the present invention, the wire diameters of the core filament 2 and the sheath filament 3 are not particularly limited, and preferably selected so as to satisfy the relationship represented by the above formula (2). . For example, the core filament 2 may have a wire diameter of 1.0 to 2.0 mm, and the sheath filament 3 may have a wire diameter of approximately 1.0 to 1.5 mm. The number of sheath filaments 3 wound around the core is preferably about 5 to 8. In the cable bead 1 of the present invention, when the sheath has two layers, the number of the sheath filaments 3 of the second sheath may be about 10 to 16.

Next, the pneumatic tire of the present invention will be described.
The pneumatic tire of the present invention is a pneumatic tire provided with a pair of bead portions respectively formed on the inner periphery of a pair of sidewall portions that are continuous with both ends of the tread portion, and the bead portion includes the cable bead of the present invention. Is buried. Since the pneumatic tire of the present invention uses the above-described cable bead 1 of the present invention as a bead core, the grip feeling, stability, and turning performance during cornering are improved as compared with the pneumatic tire using the conventional cable bead. . The cable bead of the present invention is particularly suitable for passenger car pneumatic tires and motorcycle pneumatic tires.

  FIG. 4 is a one-side cross-sectional view in the tire width direction of a pneumatic tire for a passenger car according to a preferred embodiment of the pneumatic tire of the present invention. The illustrated pneumatic tire 10 for a passenger car includes a pair of left and right bead portions 11 and sidewall portions 12, and a tread portion 13 that is continuous between both sidewall portions 12. Further, a carcass 14 made of at least one carcass ply that extends in a toroidal shape between the bead portions 11 and reinforces these portions, and a steel cord disposed on the outer side of the crown portion of the carcass 14 in the tire radial direction is a reinforcing material And at least two belt layers 15 (two layers in the illustrated example). In the tire 10 according to the present embodiment, the cable bead of the present invention is applied as the bead core 16 embedded in the bead portion 11.

  FIG. 5 is a cross-sectional side view in the tire width direction of a pneumatic tire for a motorcycle according to another preferred embodiment of the present invention. The illustrated pneumatic tire 20 for a motorcycle has a pair of left and right bead portions 21 and sidewall portions 22, and a tread portion 23 that is continuous between both sidewall portions 22. Further, a carcass 24 composed of at least one layer of carcass ply extending in a toroidal shape between the bead portions 21 and a belt 25 composed of at least one layer (two layers in the illustrated example) disposed on the crown portion of the carcass 24 are provided. Yes. Again, in the tire 20 according to the present embodiment, the cable bead of the present invention is applied as the bead core 26 embedded in the bead portion 21.

  The pneumatic tire of the present invention is not limited as long as the bead core is made of the cable bead of the present invention, and the details of the tire structure and the material of each member are not particularly limited and are conventionally known. It can be configured by appropriately selecting from the above. For example, the angle of the belt layer is, for example, 0 to 70 ° with respect to the tire circumferential direction, and bead fillers (not shown) may be disposed outside the bead cores 16 and 26 in the tire radial direction. Furthermore, a tread pattern may be appropriately formed on the back surfaces of the tread portions 13 and 23, and an inner liner may be disposed on the innermost layer of the tire. In the tire of the present invention, as the gas filled in the tire, normal or changed oxygen partial pressure, or inert gas such as nitrogen can be used.

Hereinafter, the present invention will be described based on examples.
A cable bead having a structure shown in Tables 1 to 3 below was manufactured, and a pneumatic tire for a motorcycle (tire size: 120 / 70ZR17) using the obtained cable bead was manufactured. The obtained tire was mounted on the front wheel of a motorcycle with a displacement of 1000 cc, and the test rider's feeling was evaluated for each of the grip feeling, turning performance, stability, rigidity feeling, and responsiveness. The obtained results were expressed as an index with the conventional example as 100. These results are also shown in Tables 1 to 3 below.

<Measurement of in-plane stiffness Si and out-of-plane stiffness So>
The in-plane rigidity Si is measured by using an electromechanical universal testing machine manufactured by Instron, and fixing the point A of the cable bead 1 as shown in FIG. The point was calculated by pulling the cable bead 1 radially outward and dividing the force F1 (mN) at that time by the displacement (mm). The out-of-plane rigidity So is measured using an electromechanical universal testing machine manufactured by Instron, and the cable bead 1 is supported by a pair of supports 5 as shown in FIG. 6 (b). The force F2 was applied to the center of the body 5, and the force (mN) at that time was divided by the displacement (mm).

  From Tables 1 to 3, it can be seen that the tire in which the cable bead of the present invention is applied to the bead core has improved grip feeling, stability, and turning performance without deteriorating rigidity and responsiveness.

DESCRIPTION OF SYMBOLS 1 Cable bead 2 Core filament 3 Sheath filament 4 Supply reel 5 Support body Pneumatic tire 11 for passenger cars 11 Bead part 12 Side wall part 13 Tread part 14 Carcass 15 Belt layer 16 Bead core 20 Motorcycle pneumatic tire 21 Bead part 22 Side Wall part 23 Tread part 24 Carcass 25 Belt layer 26 Bead core

Claims (4)

In a cable bead comprising: a core formed by welding both ends of a core filament so as to form an annular shape by welding; and a sheath in which a plurality of sheath filaments are spirally wound around the core;
When the rigidity with respect to the force in the same plane direction as the cable bead is Si (mN / mm), and the rigidity with respect to the force in the direction orthogonal to the same plane direction of the cable bead is So (mN / mm), the Si and the above So is the following formula (1),
0.45 ≦ So / Si ≦ 0.60 (1)
A cable bead characterized by satisfying the relationship expressed by When the wire diameter of the core filament is dc (mm) and the wire diameter of the sheath filament is ds (mm), the dc and the ds are represented by the following formula (2),
0.30 ≦ ds / dc ≦ 1.00 (2)
The cable bead according to claim 1, satisfying a relationship represented by:   The cable bead according to claim 1 or 2, wherein the number of windings of the sheath filament around the core is 7 to 10 (turns / circumference). In a pneumatic tire provided with a pair of bead portions respectively formed on the inner periphery of a pair of sidewall portions connected to both ends of the tread portion,
The pneumatic bead characterized by the cable bead as described in any one of Claims 1-3 being embed | buried in the said bead part.

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