JP2000190707A - Pneumatic radial tire for passenger car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire for passenger car reducing manufacturing cost and securing durability for using steel material in a carcass layer. SOLUTION: At least one of one to six steel element wires 21 with element wire diameter(d) ranging from 0.10 to 0.25 mm is corrugated in spiral form. These steel element wires 21 are aligned without twisting into a steel element wire bundle 20. A carcass layer 2 is formed by embedding the steel wire bundles 20 into rubber. The spiral pitch P of the corrugation is set to 10d to 56d in relation to the element wire diameter(d). If a parameter F obtained from the spiral diameter D of corrugating, the spiral pitch P, and the element wire diameter(d) is designated as (D-d)/P, the parameter F will range from 0.01 to 0.03.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire using a steel material for a carcass layer, and more particularly to a pneumatic radial tire provided with sufficient durability for a passenger car while suppressing manufacturing costs. .

[0002]

2. Description of the Related Art In general, a pneumatic radial tire has a carcass layer in which a plurality of carcass cords are arranged in a radial direction between a pair of left and right bead portions, and both ends of the carcass layer in the tire width direction are bead cores. Around the tire from the inside to the outside.

Conventionally, the use of a steel cord for a carcass layer of a tire has been frequently performed for heavy loads, but has been hardly performed for passenger cars although proposals have been made. This is because a pneumatic radial tire for a passenger car requires the use of thin steel wires from the viewpoint of durability, and a cord in which a number of such thin steel wires are twisted greatly increases the manufacturing cost. Therefore, when a steel material is used for a carcass layer of a pneumatic radial tire for a passenger car, it is required to simultaneously ensure durability and reduce manufacturing costs.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic radial tire for a passenger car which can secure sufficient durability while suppressing the production cost when using a steel material for a carcass layer. To provide.

[0005]

According to the present invention, there is provided a pneumatic radial tire for a passenger car according to the present invention, comprising 1 to 6 steel elements having a wire diameter d in a range of 0.10 to 0.25 mm. At least one of the wires is spirally corrugated, the steel wires are aligned without twisting to form a steel wire bundle, and the steel wire bundle is embedded in rubber to form a carcass layer, and The spiral pitch P of the corrugation is set to a relationship of 10d to 56d with respect to the strand diameter d, and the parameter F obtained from the corrugated spiral diameter D, the spiral pitch P and the strand diameter d is represented by (D-d) / P Where the parameter F is in the range of 0.01 to 0.03.

[0006] As described above, the steel wires having the above-described wire diameters are drawn together without twisting to form a steel wire bundle, and the carcass layer is formed using the steel wire bundle. While reducing manufacturing costs,
Sufficient durability can be ensured for passenger cars.
Moreover, by spirally corrugating at least one of the steel wires and specifying the spiral pitch P and the parameter F of the corrugation in the above ranges, the permeability of the rubber into the untwisted steel wire bundle is improved. And corrosion resistance and corrosion fatigue resistance can be improved.

In the present invention, it is preferable that both ends of the carcass layer in the tire width direction are wound around the bead core from the inside to the outside of the tire, and the winding height is set lower than the rim line. By setting the winding height of the carcass layer lower than that of the rim line in this way, it is possible to further improve durability and steering stability when a steel material is used for the carcass layer.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 illustrates a pneumatic radial tire for a passenger car according to an embodiment of the present invention. In the figure, a pair of left and right bead portions 1, 1
A single ply carcass layer 2 composed of a plurality of steel wire bundles 20 embedded in rubber is mounted between them. The carcass layer 2 is disposed so that the angle of the steel wire bundle 20 with respect to the tire circumferential direction E, E ′ is substantially 90 °, and both ends in the tire width direction are wound up around the bead core 3 from the inside to the outside of the tire. Have been. The winding end 2a of the carcass layer 2 is located radially inward of the rim line R in the tire radial direction. On the outer peripheral side of the carcass layer 2 in the tread portion 4, two belt layers 5 are arranged over one circumference of the tire. The reinforcing cords of these belt layers 5 are inclined in the range of 5 ° to 40 ° with respect to the tire circumferential directions E and E ′, and the reinforcing cords intersect each other between the layers. As a reinforcing cord of the belt layer 5, a steel cord or the like can be used.

As shown in FIG. 2, the number of steel wire bundles 20 for reinforcing the carcass layer 2 is 1 to 6, more preferably 2 to 6.
A spiral corrugation is applied to at least one of the six steel strands 21, more preferably all the strands, and the steel strands 21 are aligned in parallel without twisting. The wire diameter d of the steel wire 21 is in the range of 0.10 to 0.25 mm. If the element wire diameter d is less than 0.10 mm, the strength is insufficient, and if it exceeds 0.25 mm, the bending rigidity sharply increases, and the fatigue resistance decreases. Steel strand 21
Is preferably constant within the above range. This is because the twist is not given to the steel wire bundle 20, and if the wire diameter d of the steel wire 21 is not constant, the load is unevenly applied to the steel wire bundle 20 to cause partial breakage. This is because it easily occurs. Also,
The number of steel wires 21 in each steel wire bundle 20 is set to six or less. If the number exceeds six, the number of strands becomes too large, and it becomes difficult to align the steel strand bundle 20.

The tensile strength of the steel strand 21 is 35.
Preferably, the pressure is at least 00 MPa. This is because the specific gravity of the steel cord is 7.86, which is much higher than that of the organic fiber, and therefore, when the strand strength is low, the amount of the wire used increases and the weight increases. Therefore, it is preferable to use a material having the highest possible strength. Such a tensile strength can be achieved by increasing the carbon content of the wire constituting the steel strand to about 0.9 to 1.1% by weight or by adding alloy elements such as chromium, vanadium, silicon, and cobalt in addition to carbon. Or by adding a plurality of combinations. It can also be achieved by increasing the degree of wire drawing of the final wire drawing to 97% or more.

3 (a) and 3 (b), P is a helical pitch of the corrugated steel wire 21 and D is a helical diameter. The corrugated helical pitch P has a relationship of 10d to 56d with respect to the wire diameter d of the steel wire 21. If the helical pitch P is less than 10 d, the fatigue resistance is reduced due to excessive curling, and if it exceeds 56 d, the gauge of the carcass ply becomes unnecessarily thick. Further, the parameter F for corrugation determined from the spiral diameter D, the spiral pitch P and the strand diameter d is (D
−d) / P, the parameter F is 0.01 to
0.03. If this parameter F is less than 0.01, the rubber permeability to the steel wire bundle 20 becomes insufficient, and if it exceeds 0.03, the gauge of the carcass ply becomes unnecessarily thick. FIG. 4 shows a cross section of the carcass layer in the tire. As shown in FIG. 4, a plurality of steel strands 2
1 form a bundle to form a steel strand bundle 20. In order to provide the steel strand 21 with adhesion to rubber, it is preferable to perform an alloy plating process in which two or more elements are alloyed out of Cu, Sn, Zn, Ni, Co and the like.

As described above, the steel wires 21 are drawn together without twisting to form a steel wire bundle 20, and the carcass layer 2 is formed by using the steel wire bundles 20.
The manufacturing cost can be reduced by omitting the cord twisting step. Further, the wire diameter of the steel wire 21 is 0.10 to
By setting the thickness in the range of 0.25 mm, sufficient durability for passenger cars can be secured. Further, at least one of the steel strands 21 is spirally corrugated, and the spiral pitch P of the corrugation is set at 10 to the strand diameter d.
d to 56d, and the parameter F is set to 0.0
By specifying the content in the range of 1 to 0.03, it is possible to improve the permeability of the rubber into the non-twisted steel wire bundle 21 and to improve the corrosion resistance and the corrosion fatigue resistance.

In the pneumatic radial tire, it is preferable that the height of the winding end 2a of the carcass layer 2 be lower than the rim line R. That is, when a steel material is used for the carcass layer in a tire for a passenger car, if the winding end of the carcass layer is arranged at a position higher than the rim line as it is conventionally, the rigidity around the bead portion becomes too large, and separation occurs at the winding end. And the steering stability is reduced. On the other hand, the carcass layer 2
By making the height of the winding end 2a lower than the rim line R, it is possible to optimize the rigidity around the bead portion even when a steel material is used for the carcass layer 2, so that the separation at the turn-up edge can be reduced. Generation can be prevented and steering stability can be kept good.
The height of the winding end may be as low as lower than the rim line R, and it goes without saying that the carcass layer may not be wound at all and be held beside the bead portion, or the carcass end may be sandwiched between bead wires. In addition, the rim line R is generally a contour line or a ridge drawn on the outer peripheral side of the contact portion of the tire bead portion with the rim flange. If there is no rim line R, the winding end 2a of the carcass layer 2
Is preferably lower than the height of the flange of the rim applied to the tire.

[0014]

EXAMPLES The pneumatic radial tires for passenger cars of the conventional example, comparative examples 1-2, and examples 1-3, in which the tire size is made common to 205 / 60R15 and only the carcass structure is variously varied as shown in Table 1, respectively. Made. In the table, the carcass winding end position is indicated by the height from the rim line to the outside in the tire radial direction. For these test tires, the cord fatigue of the carcass layer, the rubber penetration into the steel wire bundle, and the load durability were evaluated. The results are shown in Table 1. As for the cord fatigue resistance, a bending deformation having a bending radius R of 22.5 mm was intermittently applied to the carcass cord, and the number of times of bending until breaking occurred was measured. The rubber permeability was determined by cutting a steel wire bundle from a tire and examining the state of penetration of the rubber, and expressed as a percentage (%) of the length of the region where the rubber had sufficiently penetrated with respect to the entire length. JIS load durability
It was evaluated by a test method based on D4230.

[0015]

[Table 1]

As can be seen from Table 1, the tires of Examples 1 to 3 can not only reduce the manufacturing cost by using the steel wire bundle as the carcass cord, but also have the same load as the conventional tire. It was durable and had good rubber penetration into the steel wire bundle. On the other hand, in Comparative Example 1, the required number of steel wire bundles could not be driven at a predetermined cord interval because the diameter of the steel wire was too small, and a tire could not be manufactured. In addition, the tire of Comparative Example 2 had poor rubber permeability to the steel strand because the corrugation parameter F was too small.

Next, when the tire size is 205 / 60R15
As shown in Table 2, pneumatic radial tires for passenger cars of Examples 4 to 6 having only different carcass structures as shown in Table 2 were manufactured. For these test tires, the occurrence of turn-up edge separation of the carcass layer and the steering stability were evaluated, and the results are shown in Table 2. The occurrence state of the turn-up edge separation is obtained by measuring the peel length at the winding end of the carcass layer after performing the same load durability test as described above. Driving stability was set at 2000 kPa for the test tires and the displacement was 2,000.
The tire was mounted on a cc passenger car and evaluated by feeling with a test driver. A case where the tire was good compared with the conventional tire was indicated by ○, and a case where the tire was poor was indicated by ×.

[0018]

[Table 2]

As can be seen from Table 2, all of the tires of Examples 4 and 5 had no separation at the winding end of the carcass layer and had good steering stability. On the other hand, in the tire of Example 6, the carcass winding end position was outside the rim line in the tire radial direction, and the rigidity around the bead portion was too high, so separation occurred at the winding end of the carcass layer and steering stability was poor. .

[0020]

As described above, according to the present invention, one to six steel strands having a strand diameter in the range of 0.10 to 0.25 mm are drawn together without twisting to form a steel strand bundle. By embedding the steel strand bundle in rubber to form the carcass layer, the cord twisting step can be omitted to reduce the manufacturing cost and ensure sufficient durability for use in passenger cars. Moreover, at least one of the steel strands is spirally corrugated, and the spiral pitch P of the corrugation is set to a relationship of 10d to 56d with respect to the strand diameter d. By setting the parameter F obtained from P and the wire diameter d in the range of 0.01 to 0.03, the permeability of rubber to the untwisted steel wire bundle is improved, and the corrosion resistance and corrosion fatigue resistance are improved. can do.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a pneumatic radial tire for a passenger car according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a steel wire bundle forming a carcass layer in the present invention.

FIGS. 3A and 3B show examples of corrugated steel wires in the present invention, wherein FIG. 3A is a side view and FIG. 3B is a cross-sectional view.

FIG. 4 is a cross-sectional view of the carcass layer in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead part 2 Carcass layer 3 Bead core 4 Tread part 5 Belt layer 20 Steel strand bundle 21 Steel strand R Rim line

Claims (2)

[Claims] 1. A spiral corrugation is applied to at least one of 1 to 6 steel wires having a wire diameter d in a range of 0.10 to 0.25 mm, and these steel wires are twisted. A steel wire bundle is prepared by aligning the steel wire bundle, the steel wire bundle is embedded in rubber to form a carcass layer, and the spiral pitch P of the corrugation is set to a relationship of 10d to 56d with respect to the wire diameter d, When a parameter F obtained from the corrugated spiral diameter D, the spiral pitch P, and the wire diameter d is (D−d) / P, the air for a passenger car in which the parameter F is in the range of 0.01 to 0.03. Included radial tire. 2. The pneumatic radial tire for a passenger car according to claim 1, wherein both ends in the tire width direction of the carcass layer are wound around the bead core from the inside to the outside of the tire, and the winding height is lower than a rim line.