JPH0681283A - Radial tire - Google Patents

Abstract

PURPOSE:To improve the durability, reduce the flexural rigidity and improve the comfortableness to ride by completely filling a rubber in a steel cord in a radial tire using the steel cord in a belt layer. CONSTITUTION:This radial tire is obtained by curving two core element wires 11 into a wavy form in the vertical direction relatively to the parallel plane while keeping the parallel state and wrapping 2 to 3 lateral element wires 12 around the two core element wires 11 at a pitch equal to the curving pitch of the core element wires in a steel cord 10 of a belt layer formed from the two core element wires 11 having an equal diameter and the 2-3 lateral element wires 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention provides a comfortable ride and
The present invention also relates to a radial tire which has excellent durability and is suitable for passenger cars and light trucks.

[0002]

2. Description of the Related Art A radial tire for an automobile, in which one or a plurality of belt layers each made of a steel cord inclined with respect to the cord direction of the carcass layer is laminated around a carcass having a radial cord arrangement, is used as a steel for the belt layer. 1x4 4 to 5 steel strands with the same diameter as the cord
Alternatively, a steel cord formed by twisting a 1 × 5 structure is known. Also, JP-A-57-19
Japanese Patent No. 3253 and Japanese Patent Publication No. 3-23673 disclose a steel cord in which two core wires having the same diameter and two or three side wires are twisted together, that is, a structure of 2 + 2 or 2 + 3. Steel cords are disclosed.

[0003]

However, 1 × 4
Or, the steel cord of 1 × 5 structure has four or five strands arranged in a circle in the cross section and closely contact with each other to form a closed space where rubber does not enter in the center. Upon receiving the water, water penetrates into the above-mentioned closed space and rust is generated on the strands, the adhesiveness with the rubber is deteriorated, and the belt layer is easily peeled off. Is evenly twisted and curved, so bending rigidity (bending hardness)
However, when used in the belt layer, the cushioning property is deteriorated and the riding comfort is poor.

In addition, 4 + 5 wires having the same diameter are 2 + 2
Or, when twisted into a 2 + 3 structure, it is more difficult to form a closed space than with a steel cord with a 1 × 4 or 1 × 5 structure, and the adhesiveness of rubber is improved. It is manufactured by winding two or three side strands closely attached to the surrounding two core strands, so that the plane formed by the two core strands and the two or three side strands are formed. In the portion where the plane formed by is aligned in parallel with each other, the core wire and the side wire are in contact with each other to form a partially closed space, so that a complete rubber coating of the wire is not obtained, Moreover, since the bending rigidity of the steel cord is high, there is a problem that when used in the belt layer, the cushioning property is low and the riding comfort becomes poor.

According to the present invention, the belt layer is 2 + 2 or 2+.
In the radial tire using the steel cord of structure 3, the rubber completely enters the steel cord, so that even if the tire is damaged, water does not penetrate into the steel cord, and therefore the strand does not It is intended to provide a radial tire that is free from rust, has a flexible belt, is easily damped in vibration, and has a good riding comfort.

[0006]

A radial tire of the present invention comprises a carcass of a radial cord arrangement and a belt layer surrounding the carcass, and a steel cord forming the belt layer has a diameter of 0.175 mm or more and 0.27 mm or less. A radial tire having four or five strands having the same diameter and two constituting the core strand, the two core strands being parallel to each other while maintaining the parallel state. Is bent in a vertical direction into a waveform, and the amplitude of the waveform curve formed by these two core wires is 0.5 times or more and 2 times or less of the wire diameter,
The pitch is 7 mm or more and 20 mm or less, and 2 to 3 side strands are wound around the two core strands at a pitch equal to the bending pitch of the core strands.

The amplitude referred to in the present invention is the height of the crest of the peak with respect to the bottom of the valley of the wavy curve formed by the center line of the strand. Then, the steel cord is formed by aligning two core wires and imprinting the corrugated curve, and
It is manufactured by aligning two or three side strands with one core strand and rotating one of the core strand or the side strand.

[0008]

Operation: Two core wires in a parallel state are curved in a waveform in a direction perpendicular to their parallel planes, and the two core wires are provided with a pitch equal to the curve pitch of the waveform on two to three sides. Since the strands are wound, the side strands enter inside the curved portions of the two core strands, and the parallel planes of the core strands and the parallel planes of the side strands are parallel to each other. The strands and side strands do not come into contact with each other, and a void is formed between them. Therefore,
When rubber is drawn, the rubber completely enters the steel cord from the above-mentioned voids and the exposed space of the wire disappears, so even if the tire is damaged, water will enter the steel cord and Rust is not generated, delamination of the tire is reduced, and tire durability is improved. Moreover, since the core wire is curved in a corrugated shape, the bending rigidity of the steel cord is lowered, and the cushion of the tire using this steel cord in the belt layer is softened and the riding comfort is improved.

However, when the wire diameter is less than 0.175 mm, the number of wire drawing steps increases, the rate of wire breakage during wire drawing increases, and the manufacturing cost of steel cord rises.
If it exceeds, the rigidity of the steel cord is increased and the riding comfort and fatigue are deteriorated. When the number of core wire is one, the side wire is slippery with respect to the core wire, and the winding shape becomes unstable. On the other hand, when the number is three or more, it becomes difficult to maintain the parallel state. A void easily occurs between the core wires. In addition, when the number of side strands is one, the strand diameter must be increased in order to obtain the required tension, which results in excessive bending rigidity, reduced riding comfort, and fatigue resistance. If the number is four or more, on the contrary, it becomes difficult to control the tension of the side wire, and the core wire cannot be wound into a desired shape.

When the amplitude of the corrugated bending of the core wire is less than 0.5 times the wire diameter, the core wire and the side wire contact each other to prevent rubber from penetrating into the steel cord, and the steel wire The rigidity of the cord is not sufficiently reduced, and the riding comfort is reduced,
On the other hand, if it exceeds 2 times, the thickness when the steel cords are arranged and rubberized becomes excessive, the weight of the tire increases, and the rigidity decreases and the cornering performance deteriorates. When the pitch of the above-mentioned wavy curve is less than 7 mm,
When the steel cord is manufactured, the efficiency is lowered and the manufacturing cost is increased. On the contrary, when it exceeds 20 mm, the fatigue property of the cord is lowered.

[0011]

1 shows a steel cord 10 having a structure of 2 + 2, 11 is a core wire, 12 is a side wire, and 2
The core wires 11 of the book are juxtaposed in a plane perpendicular to the plane of the drawing, and are curved in a wavy shape in the drawing, and their amplitude is H.
, And the pitch is indicated by P. Two side strands 12, 12 are wound around the two core strands 11, 11 at the pitch P described above. And the core wires 11 and 1
Inside the curved portion of 1, the side wires 12, 12 are core wires 11, 1,
1, and a void 13 is formed between them as shown in FIG. Further, FIG. 3 is a cross section of a steel cord having a structure of 2 + 3, and like the case of FIG. 2, three side wires 12 are positioned in parallel in parallel with each other inside the curved portion of the two core wires 11. is doing.

Five kinds of steel strands having different diameters were manufactured using a steel material having a carbon content of 0.82%, and the steel strands were used for the core strand 11 and the side strands 12 and the above 2 + 2 was used.
Alternatively, a total of 20 types of steel cords having a structure of 2 + 3 and different in amplitude and pitch of the corrugated curve and Examples 1 to 8 and Comparative Examples 1 to 12 were manufactured (however, the steel cord having a structure of 2 + 3 is an example. 4 and Comparative Example 2 and the rest all had a structure of 2 + 2). The wire diameter, amplitude, pitch and strength of these steel cords are shown in Table 1 below. In Table 1, the amplitude is "horizontal"
Those marked with are those in which the two core wires are not vertically curved perpendicular to the parallel plane but are laterally curved in the parallel plane.

Table 1 Element wire diameter (mm) Amplitude (mm) Pitch (mm) Strength (kgf) Example 1 0.175 0.193 14.0 30.0 Example 2 0.25 0.275 14.0 60.0 Example 3 0.27 0.33 14.0 69.0 Example 4 0.23 0.253 14.0 66.0 Comparative Example 1 0.25 Horizontal 0.275 14.0 60.0 Comparison Example 2 0.23 Horizontal 0.253 14.0 66.0 Comparative Example 3 0.30 0.385 14.0 85.0 Comparative Example 4 0.25 0.275 23.0 60.0 Comparative Example 5 0. 25 0.275 6.0 6.0 0.0 Comparative example 6 0.25 0.12 14.0 60.0 Comparative example 7 0.25 0.080 20.0 60.0 Example 5 0.25 0.125 20 0.0 60.0 Example 6 0.25 0.125 7.0 60.0 Comparative Example 8 0.25 0.125 25.0 60.0 Comparative Example 9 0.25 0.125 6.0 60.0 Example 7 0.25 0.500 20.0 60.0 Example 8 0.25 0.500 7.0 60. 0 Comparative Example 10 0.25 0.500 23.0 60.0 Comparative Example 11 0.25 0.500 6.0 60.0 Comparative Example 12 0.25 0.600 7.0 60.0

A radial tire of size 205 / 60R15 was manufactured using the above steel cord as a belt. However, the number of belts is two, and the inclination angle of the steel cord is 2 for the first piece on the carcass side to the right of the equator.
The second sheet was inclined at an angle of 22 degrees to the left.
Further, polyester cords (1000 denier x 2) were arranged in the carcass at a density of 22 cords / inch. The results of testing the end number of the steel cord and the performance of the obtained tire are shown in Table 2 below.

Table 2 Fatigue End Number Rubber Invasion Ride Comfort Cornering (× 1000 cycle) (pieces / inch) Performance Example 1 30128 42.0 10.0 10.0 10.0 Example 2 16010 21.0 10. 0 9.0 9.0 Example 3 12030 18.2 10.0 10.0 8.0 Example 4 17985 19.0 10.0 9.5 9.5 Comparative Example 1 15079 21.0 7.07 .0 7.0 Comparative Example 2 11230 19.0 7.0 7.5 7.5 Comparative Example 3 3120 15.0 10.0 3.0 4.0 Comparative Example 4 10030 21.0 10.0 7.0 7.0 Comparative Example 5 11500 21.0 9.5 7.0 7.0 Comparative Example 6 10115 21.0 7.5 7.0 7.5 Comparative Example 7 9000 21.0 7.0 4.0 7.0. 5 Example 5 14900 21.0 10. 8.0 8.0 Example 6 16015 21.0 10.0 9.0 8.0 Comparative Example 8 11100 21.0 7.5 5.5 7.5 Comparative Example 9 9500 21.0 8.0 7. 0 6.0 Example 7 15500 21.0 10.0 10.0 9.0 9.5 Example 8 17012 21.0 10.0 8.5 9.0 Comparative Example 10 10100 21.0 10.0 7.0 6 Comparative Example 11 9300 21.0 10.0 7.0 5.0 Comparative Example 12 11300 21.0 10.0 9.0 4.0

In Table 2 above, the fatigue resistance is determined by coating the steel cord with a predetermined number of ends and vulcanizing it, and then obtaining a rubberized cord having a width of 24.5 mm and a length of 350 mm.
The sample was cut out, wound in a U-shape on a pulley having a diameter of 1 inch, reciprocated under a tension of 40 kg, and the number of reciprocations until breakage was shown. Further, the rubber invasion property is a result obtained by the evaluator loosening the cord taken out from the tire in the longitudinal direction and determining the rubber invasion degree by the 10-point method. The riding comfort and the cornering performance are shown as the average value of the results of a sensory test with 10 drivers running on a test course owned by the applicant and on a general road.

As can be seen from Tables 1 and 2 above, Examples 1 to 8 of the present invention are all excellent in all of fatigue resistance, rubber penetration, riding comfort and cornering performance. In terms of penetrability, each is 10 points. On the other hand, in Comparative Example 1 and Comparative Example 2, since the two core wires were laterally curved in the parallel plane, rubber penetration was poor, and riding comfort and cornering performance were low. Further, in Comparative Example 3 in which a thick wire was used, the strength was improved, but the fatigue resistance was reduced, and the riding comfort and cornering performance were extremely deteriorated.

Further, Comparative Examples 4, 8 and 10 were inferior in fatigue resistance and riding comfort because the pitch of the corrugated curve was long. On the contrary, Comparative Examples 5, 9 and 11 having a short pitch are inferior in ride comfort and cornering performance,
Moreover, the cost was high. In addition, Comparative Examples 6 and 7
Since the core wire has a small amplitude, fatigue resistance, rubber penetration, riding comfort, and cornering performance are reduced, and the riding comfort of Comparative Example 7 in which the amplitude is particularly small deteriorates. Further, in Comparative Example 12, the cornering performance is low because the amplitude is excessive.

[0019]

As described above, according to the present invention, the two core wires in which the steel cords constituting the belt are in the parallel state are bent in a waveform in the direction perpendicular to the parallel planes, and the above-mentioned waveform It is formed by winding 2 to 3 side strands at the same pitch as the bending, and the diameter of the strand is 0.
The core wire and the side wire are 175 to 0.27 mm, the amplitude of the corrugation is limited to 0.5 to 2.0 times the wire diameter, and the bitch is limited to 7 to 20 mm. Will not come into contact with the rubber and the rubber penetration will be good,
Therefore, even if the tire is damaged, water does not penetrate into the steel cord to cause rust on the wires, delamination of the tire is reduced, and durability of the tire is improved. Moreover, since the core wire is curved in a corrugated shape, the bending rigidity of the steel cord is lowered, and the cushion of the tire using this steel cord in the belt layer is softened and the riding comfort is improved.

[Brief description of drawings]

FIG. 1 is a front view of a steel cord using two side wires.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view of a steel cord using three side wires.

[Explanation of symbols]

 10: Steel cord 11: Core wire 12: Side wire 13: Void between wires H: Amplitude of core wire P: Pitch

Claims (1)

[Claims] 1. A carcass having a radial cord arrangement and a belt layer surrounding the carcass, and steel cords forming the belt layer have a diameter of 0.175 mm or more and 0.27 mm or less, and have four or five equal diameters. In a radial tire composed of two strands, two of which constitute a core strand, the two core strands are curved in a waveform in a direction perpendicular to the parallel plane while keeping the parallel state. The amplitude of the corrugation formed by the two core strands is 0.5 times the strand diameter or more 2
Double or less, the pitch is 7 mm or more and 20 mm or less, and the two core wires are wound with 2-3 side wires at a pitch equal to the bending pitch of the core wires. Radial tires.