JPH0655908A - Belt structure for radial tire - Google Patents

Abstract

PURPOSE:To provide a radial tire belt which is light and has high inplane bending stiffness and good size stability by arranging linear cords and corrugated cords alternately inside a rubber matrix. CONSTITUTION:Linear cords 6 and corrugated cords 7 are arranged alternately inside a rubber matrix of belts 4a, 4b. As a substitute, linear wires and corrugated wires are arranged alternately, or linear cords and corrugated wires are arranged alternately. These wires are made of high carbon steel containing more than 0.6% of carbon content and have plating which applies rubber adhesiveness onto their outermost layers, while their ratios of wave height H to wire radii (d), H/dX100, are set to be more than 130%. The reduction in a count of placing the cords by using high strength steel cords or high strength steel wires performs such improvements as lightening of the belt, an improvement in inplane bending stiffness and size stability, an improvement in automobile performance and controlling performance for a vehicle, reduction in tire abrasion, and reduction in rolling resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt structure for radial tires.

[0002]

2. Description of the Related Art In steel tires for automobiles, especially radial tires, a steel cord layer called a belt is formed on the outer peripheral crown portion of a carcass.
One or more layers are provided as a reinforcing layer. As shown in FIG. 8 (a), this belt is configured as a band body in which a large number of linear cords 100 are embedded in a rubber matrix 5 at a required angle and is embedded in the tire circumferential direction (cord longitudinal direction). In addition to the tensile strength of), the rigidity and dimensional stability against bending are emphasized from the viewpoint of tire performance. The former belt rigidity, in particular the in-plane bending rigidity, is an important factor in that its large value improves the dynamic performance and maneuverability of the vehicle, reduces tire wear, and lowers the rolling resistance of the tire.

By the way, in recent years, there has been an increasing demand for weight reduction of tires, and in order to respond to this demand, efforts have been made to improve the tensile strength of steel cords by adjusting components such as carbon content, wire drawing method (drawing method) and heat treatment method. Was made, 350
Practical application of high-strength steel cords in the 0-4000 Mpa class is progressing. The practical use of such high-strength steel cords makes it possible to reduce the diameter of the steel cords, and it is also possible to reduce the number of driving cords per unit width of the belt, which also makes it possible to sufficiently satisfy the belt tensile strength. You can However, in the conventional radial tire belt, the diameter of the cord is small and the number of hammered-in wires is small.
When the belt is pulled in the longitudinal direction as shown in Fig. 8, the rubber expands and contracts and the distance between the cords changes, so that the belt is easily deformed, the width of the belt becomes narrow, and the entire belt easily expands. When an external force is applied as in b), the rubber between the cords is deformed and the positional relationship of the cords is displaced, so that the belt is greatly distorted, and it is difficult to satisfy the rigidity and dimensional stability of the belt.

The present invention was devised to solve the above-mentioned problems, and its purpose is to provide a radial tire that is lightweight, has high in-plane bending rigidity, and has good dimensional stability. The purpose is to provide a belt.

[0005]

In order to achieve the above object, the present invention is one in which linear cords and corrugated cords are alternately arranged in a rubber matrix. The present invention also includes alternating linear wires and corrugated cords, alternating linear wires and corrugated wires, or alternating linear cords and corrugated wires in a rubber matrix. In the above invention, the wavy cord or wavy wire has a plating that imparts rubber adhesiveness to the outermost layer, which is made of high carbon steel having a carbon content of 0.6% or more, and has a wave height of
A wire or cord diameter of 130% or more is preferable.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an example of a radial tire to which a belt structure according to the present invention is applied. Reference numeral 1 is a bead portion, 2 is a crown portion having a tread 20, 3 is a radial cord arranged from the bead portion to the crown portion, 4a. , 4b are belts of a plurality of layers embedded below the tread 20. The belts 4a and 4b have steel cords arranged on the rubber matrix 5 at a predetermined angle, and the angles of the steel cords are opposite to each other for the belts 4a and 4b.

Although such a structure is similar to that of a conventional belt, in the present invention, instead of using straight steel cords and arranging them in parallel, the steel cords are arranged as shown in FIGS. 2 and 3. 2 types of linear cords 6 and wavy cords 7 are used, and the linear cords 6 and the wavy cords 7 are alternately arranged. FIG. 4 shows a second embodiment of the present invention in which straight wires 6'and corrugated wires 7'are arranged alternately. FIG. 5 shows a third embodiment of the present invention in which linear cords 6 and wavy wires 7'are arranged alternately. In addition, the present invention also includes a linear wire and a wavy cord arranged alternately.

In the embodiment shown in FIG. 3, the cord has a 3 + 6 structure, and in the embodiment shown in FIG. 5, the cord has a 1 × 5 structure, but the present invention is not limited to these. 1 × 4, 2 + 7, 3+
It is possible to employ various structures such as 9, 7 × 3, 7 × 4, 7 × 7, a compact type in which adjacent wires are in contact with each other, or at least a part of the adjacent wires are separated from each other. Various configurations such as an open type, a cross twist type, and a parallel twist type can be adopted. In each of the examples, the straight wire 6'and the wavy wire 7'generally have a carbon content of 0.6% or more, and a diameter of 0.05 to 0.7% made of high-carbon steel of 0.05 to 0.92%. ~ 0.80mm steel wire is used to improve adhesion with rubber,
The outermost layer is plated with copper, brass, zinc or an alloy containing them as a main component. The linear cord 6 and the corrugated cord 7 are twisted by using a plurality of such wires (filaments). Further, in the present invention, “alternate” is not necessarily limited to the case where the straight cord 6 (or the straight wire 6 ′) and the wavy cord 7 (or the wavy wire 7 ′) are arranged one by one, and the straight line This also includes a case where the relationship in which two cords 6 (or linear wires 6 ′) are arranged and then one or more corrugated cords 7 (or corrugated wires 7 ′) are arranged is repeated.

FIG. 6 shows a wavy wire 7 ', which is a two-dimensional wave 7 having an equal height alternately with respect to the center line c.
0 and 70 are formed at a predetermined pitch P. Wave height H
Is at least 130%, preferably 200% or more in relation to the wire diameter d (H / d × 100), and the upper limit is about 500%. The reason for this is that in-plane bending rigidity is sufficient to obtain resistance to deformation, the adhesion area with the rubber to be increased, and elongation at break, which is an important physical property of the rubber reinforcing material, is 2.5. % Or more, and further, residual stress on the wire surface due to wire drawing (α-F from X-ray diffraction method)
This is because the fatigue resistance can be improved by making the residual stress of the low tensile or compression side inside and outside of the bending work in the circumferential direction (a value obtained from the 200 crystal spacing of e)). However, the wave height ratio (H / d × 100) is 500%
If it is above, the driving density of the wire will be insufficient,
It is not preferable because the strength becomes insufficient. The linear diameter ratio (P / d) of the pitch is 2 or more, and the upper limit is about 8. Figure 7 shows a wavy code 7 with 2
The dimensional waves 70, 70 are formed at a predetermined pitch P. The height H of the wave is related to the wire diameter d (H / d × 1
00) is at least 130%. The reason is the same as described above. The corrugated wire 7'is made by plating, then linearly drawing it by a cold drawing method using a die, and then crimping it using a pair of rotatable tooth molds. . It should be noted that the wavy shape is mainly bent on a two-dimensional surface, but in some cases it may be 3
It may have a fine spiral shape.

In the belt of the present invention, the linear cords 6 or the linear wires 6'and the corrugated cords 7 or the corrugated wires 7'are alternately arranged in the rubber matrix 5 to be bonded and integrated with the rubber matrix 5. . Therefore, the rigidity against bending in the same plane as the paper surface in FIG. 2 is increased,
Even if tension is applied in the longitudinal direction of the belt as shown by the white arrow, the straight portions 7 and 71 between the bent portions of the wavy cord 7 or the wavy wire 7'and the rubber matrix adhered thereto are integrated and the resistance is increased. Exert an effect. That is, it acts as if it were a truss structure. For this reason, the conventional belt is narrowed and the deformation such that the entire belt is stretched is reduced. This also applies when a compressive force is applied in the belt longitudinal direction. Further, even if an external force is applied in different width directions as shown by the black arrow in FIG. 2, distortion is unlikely to occur. Therefore, it is possible to improve the bending rigidity and the dimensional stability while taking advantage of the lightness due to the high strength of the cord or the wire.

In addition, when the wave height ratio of the cord or wire is set within the above range, in addition to ensuring a proper breaking elongation, the bending diameter of the wavy bent portion is small at the time of wave processing, and the bent top portion is bent. Is a buckling type process and tries to spread the angle between the straight sides from the inside of the bent top. As a result, when the cord or wire leaves the tooth profile, the bending top part rather contracts (springback phenomenon), so
The outside of the bending apex shows a low tensile stress and the inside shows a compressive residual stress, so that the residual stress associated with the drawing process can be reduced. If the wave height ratio is too small, only loose simple bending is performed between the tooth forms, and since the bending diameter is large, elongation behavior occurs in the longitudinal direction when the wire or cord leaves the tooth form. It is difficult to obtain the characteristics.

[0012]

According to the present invention described above, the belt can be made lighter by reducing the number of cords to be driven by using the high-strength steel cord or steel wire, and the in-plane bending rigidity and dimensional stability can be obtained. It has excellent effects such as improvement in vehicle dynamic characteristics and maneuverability, reduction in tire wear, and reduction in rolling resistance.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of a radial tire to which a belt according to the present invention is applied.

FIG. 2 is a cross-sectional view of the belt according to the present invention.

FIG. 3 is a partially enlarged sectional view of FIG.

FIG. 4 is a partially enlarged sectional view showing a second embodiment of the present invention.

FIG. 5 is a partially enlarged cross-sectional view showing a third embodiment of the present invention.

FIG. 6 is a side view of the wavy wire used in the present invention.

FIG. 7 is a side view of the wavy cord used in the present invention.

FIG. 8 is a cross-sectional view showing a state of a conventional radial tire belt when no load is applied and a state where an external force is applied.

[Explanation of symbols]

 4a, 4b Belt 6 Straight cord 6'Straight wire 7 Wavy cord 7'Wavy wire

Claims (5)

[Claims] 1. A belt structure for a radial tire, wherein linear cords and corrugated cords are alternately arranged in a rubber matrix. 2. A belt structure for a radial tire, wherein straight wires and wavy wires are alternately arranged in a rubber matrix. 3. A belt structure for a radial tire, characterized in that straight cords and wavy wires are arranged alternately in a rubber matrix. 4. The wire is made of high carbon steel having a carbon content of 0.6% or more and has a plating for imparting rubber adhesion to the outermost layer,
The belt structure of a radial tire according to any one of claims 1 to 3, wherein the ratio of the wave height H to the wire diameter d (H / d x 100) is 130% or more. 5. The wire is made of high carbon steel having a carbon content of 0.6% or more and has a plating for imparting rubber adhesion to the outermost layer,
The belt structure for a radial tire according to claim 1, wherein a ratio (H / d × 100) of the wave height H to the cord diameter d is 130% or more.