JP5748944B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more particularly, to a pneumatic tire provided with a reinforcing layer in which a steel wire is wound in a spiral shape substantially in the tire circumferential direction.

  In general, a belt layer reinforced with fibers is disposed in a crown portion of a pneumatic tire. As one of the functions of the belt layer, there is an effect on the force acting in the tire circumferential direction. Due to this effect, the belt layer is also important from the viewpoint of durability, for example, it is possible to prevent the protrusion of the tire crown due to the centrifugal force acting when the tire rotates at a high speed. Further, the rigidity in the tire circumferential direction contributes to the in-plane rigidity of the belt, and contributes to the exertion of lateral force during turning.

  In this respect, the pair of cross belt layers arranged so as to cross each other at an angle with respect to the tire circumferential direction can also increase the circumferential rigidity by bringing the angle closer to the tire circumferential direction. In order to obtain rigidity, a new reinforcing layer is also provided in the tire circumferential direction.

  Usually, an organic fiber is used as a reinforcing material of the circumferential reinforcing layer. When a steel wire is used as such a reinforcing material, the circumferential rigidity is further increased, but the rigidity is too high, and the workability and yield in the tire manufacturing process are deteriorated, and the grounding property to the ground is deteriorated. If the grounding property is deteriorated, sufficient turning performance cannot be obtained even if the circumferential rigidity is increased.

  On the other hand, for example, in Patent Document 1, in a tire including a reinforcing layer in which the reinforcing material is arranged substantially in the tire circumferential direction, a metal wire that is three-dimensionally shaped and increased in elongation is used as the reinforcing material. Thus, there is disclosed a technique for securing the ground contact property while improving the circumferential rigidity and further improving the fatigue property.

JP 2009-23508 A (Claims etc.)

  However, in the steel wire material whose elongation is increased by molding, the strain at the time of rolling increases due to the elongation, and the fatigue property may be inferior.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire that improves turning performance and further improves fatigue performance by ensuring contactability while increasing circumferential rigidity.

  In order to solve the above-mentioned problems, the present inventors have intensively studied, as a result of defining the properties of the steel wire, to make the steel wire with increased initial elongation and ductility, this steel wire as a circumferential reinforcing member By applying this method, it was found that a tire having improved ground contact property while improving circumferential rigidity and further ensuring fatigue properties was obtained, and the present invention was completed.

That is, the present invention is a tire provided with a reinforcing layer in which a steel wire is spirally wound in a substantially tire circumferential direction,
The steel wire is an untwisted cord made of a bundle of one typed strand or two typed strands,
The steel wire has an elongation of 1.8 to 2.4% at a tension of 1000 MPa with a rubber attached,
The wire diameter of the steel wire is 0.30 to 0.34 mm, and
A strength Ts defined by T / S with respect to the breaking strength T (N) and the cross-sectional area S (m ² ) of the steel wire is 2500 MPa.

  In this invention, it is preferable that the said steel wire consists of high carbon steel with a carbon content of 0.8-1.0 mass%. Moreover, it is preferable that the steel wire material is a bundle of two strands formed in a spiral shape.

  Further, in the present invention, the reinforcing layer passes a plurality of the steel wire wound around separate reels through a single base, and is then covered with rubber to obtain an intermediate material of a rubber composite, Preferably, the intermediate material is formed by winding a tire in a tire forming process. After passing a plurality of the steel wire wound on separate reels through one slit, the rubber is pressed from above and below to form rubber. It is also preferable that the composite is obtained by obtaining an intermediate material of the composite and winding the intermediate material in a tire molding process.

  Furthermore, after the reinforcing layer has been molded with respect to the strands, the molded strands are covered with rubber without winding the molded strands, and the rubber-coated strands are covered. It is also preferable that the wire is formed by winding a tire in a tire forming process. In this case, the reinforcing layer does not wind up the rubber-coated wire after the molded wire is covered with rubber. Further, it is more preferably formed by winding in a tire molding step.

  The pneumatic tire of the present invention is particularly suitable as a motorcycle tire.

  According to the present invention, it is possible to improve the turning performance by securing the ground contact property while increasing the circumferential rigidity, and further, it is possible to realize a pneumatic tire with further improved fatigue properties.

1 is a schematic cross-sectional view showing a pneumatic radial tire for a motorcycle according to an example of the present invention. It is sectional drawing which shows the cord structure which concerns on an Example. It is sectional drawing which shows the other cord structure which concerns on an Example. It is sectional drawing which shows the other cord structure which concerns on an Example. It is sectional drawing which shows the other cord structure which concerns on an Example. It is sectional drawing which shows the other cord structure which concerns on an Example.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic cross-sectional view of a motorcycle tire according to an example of the present invention. As shown in the drawing, the motorcycle tire of the present invention includes a tread portion 11, a pair of sidewall portions 12 disposed on the inner side in the tire radial direction from both edge portions thereof, and a bead portion 13 connected to the inner side in the tire radial direction. And at least one layer of carcass ply in which each of these parts is reinforced between the bead cores 21 embedded in the bead part 13 and the cord forming 60 to 90 degrees with respect to the tire equatorial plane is covered with rubber. The carcass layer 22 and at least one spiral belt layer 23 in which a steel wire is spirally wound in the tire circumferential direction are provided on the outer side in the tire radial direction.

  In the present invention, the steel wire rod as the reinforcing material used for the spiral belt layer 23 as the circumferential reinforcing layer was molded with an elongation at 1000 MPa tension of 1.3% or more with rubber attached. Use steel wire. By using such a steel wire with good elasticity for the spiral belt layer 23, even when a large lateral force is applied to the tire, the tire tread portion is well grounded to the edge, and the turning performance can be improved. . On the contact surface, the tire, which is originally a curved surface, will be pulled or compressed depending on the location in order to fit on a flat road surface. In particular, the difference becomes large when braking or turning a corner. At that time, by applying a steel wire having an elongation at 1000 MPa tension of 1.3% or more with rubber attached, tension and compression are absorbed, sufficient ground contact area is secured, and the wire is bent. Since no floating part is formed, a uniform pressure is applied to the entire ground surface, and a frictional force can be effectively applied. As a result, the feeling during braking and cornering can be improved. In particular, it is preferable to use a steel wire having an elongation of 1.5 to 3.0% at 1000 MPa tension with a rubber attached.

On the other hand, since inputs such as tension, compression, and torsion are added to the circumferential reinforcing layer, a cord having a large stretchability will be greatly distorted, and in a steel wire normally used for a reinforcing layer of a tire, It becomes inferior to fatigue when used for a long time. Therefore, as the steel wire according to the present invention, the strength Ts (MPa) defined by T / S obtained by dividing the breaking strength T (N) by the cross-sectional area S (m ² ), the strength Ts ≦ 3000, preferably Those satisfying 2000 ≦ Ts ≦ 3000 are used. Thereby, the ductility of a steel wire can be made high and the fatigue property with respect to a tension | pulling, compression, and a twist can be improved. Such a steel wire is obtained by reducing the processing amount at the time of wire processing, and in that case, it is preferable to use a high carbon steel having a carbon content of 0.8 to 1.0 mass%.

  As the steel wire according to the present invention, in addition to the typed strands, those obtained by bundling the typed strands or those obtained by twisting the typed strands can be used. In the case of cords of double twist or rung twist, cords rub against each other at the contact point between the strands, and sufficient fatigue and strength cannot be obtained. In order for the tire to exert a lateral force when turning, it is preferable that the bending rigidity of the steel wire used for the circumferential reinforcing layer is high, and the strand diameter of the steel wire is preferably 0.25 mm or more. On the other hand, from the viewpoint of ride comfort performance, the wire diameter of the steel wire is preferably 0.40 mm or less. Furthermore, the number of the strands in the case where the shaped strands are bundled or twisted together can be 1 to 12, for example.

  In the present invention, it is particularly preferable to use a steel wire that is formed by bundling strands of strands. As a result, since the strands do not contact each other even under tensile input, the original cord strength can be reliably obtained. In this case, in order to make it difficult for the adjacent strands to come into contact with each other, it is preferable that the spiral forming of the strands is substantially the same pitch. More specifically, a rubber-steel cord composite formed by bundling two or more strands spirally formed at substantially the same pitch and bundling them in substantially the same phase without being twisted is preferably used. Can be used. In this case, it is preferable that circumscribed circles of the forming spiral of any one of the strands and at least one other strand overlap each other. High rigidity and high strength can be obtained by arranging the strands constituting the rubber-steel cord composite so that the circumscribed circles of the molds overlap each other. Furthermore, in this case, it is also preferable that all the strands have the same strand diameter and the amount of molding, whereby stress is uniformly applied to each strand, and the strength efficiency can be improved.

  The reinforcing layer using the steel wire according to the present invention is, for example, a method in which a plurality of steel wires wound on separate reels are passed through a single base and then covered with rubber to provide an intermediate material for the rubber composite. The method of forming the intermediate material by wrapping it in the tire molding process, or passing a plurality of steel wires wound on separate reels through one slit and then pressing the rubber from above and below to form a rubber composite In addition to the method of obtaining the intermediate material and winding the intermediate material in the tire molding process, after forming the element wire, the formed element wire is made of rubber without winding the formed element wire. After coating, the rubber-coated element wire can be suitably formed by a method in which it is wound and formed in a tire molding step without further winding.

  The tire of this invention should just be provided with the circumferential direction reinforcement layer which consists of the said steel wire, and it does not restrict | limit in particular about the tire structure other than that, the material of each structural member, etc. For example, the number of shots of the steel wire rod in the spiral belt layer can be in the range of 7 to 250 pieces / 50 mm.

Hereinafter, the present invention will be described in more detail with reference to examples.
A rubber-steel cord composite according to the conditions shown in the following table using steel wires (filaments or strands (brass plating: Cu 63 mass%, Zn 37 mass%)) molded at the molding amount and molding pitch shown in the table below As coating rubber, natural rubber (NR) 100 parts by mass, carbon black (HAF) 55 parts by mass, zinc oxide (ZnO) 7 parts by mass, sulfur 5 parts by mass, Co salt (naphthenic acid) A rubber composition composed of 0.1 part by mass of cobalt was used.

  Each rubber-steel cord composite obtained is applied to a spiral belt layer of a pneumatic radial tire for a motorcycle (tire size: 190 / 50ZR17) having a spiral belt structure shown in FIG. Evaluation was made according to the following for the sexual feeling and the corner feeling. These results are also shown in the table below. In each tire, the spiral belt layer is formed by passing a predetermined number of steel filaments wound on separate reels through one base and then covering with rubber to obtain an intermediate material of the rubber composite. Was formed by winding in the tire molding process.

<Fatigue>
Peel off the inner liner of each test tire, put water in the tire, run the drum at 15,000 km at low internal pressure, take out the belt cord of the tire, and reject the one where the cord breakage occurred (× ), Those that did not occur were accepted (◯).

<Ride comfort feeling and corner feeling>
Each test tire is mounted on a 1000cc sports type motorcycle with a rim size of MT 6.00x17 and an air pressure of 250 kPa, and is run on a test track. The ride feeling feeling, corner turning feeling and corner The limit feeling was evaluated based on the test driver feeling (10 points maximum). In any case, the score is 8 or more.

  As shown in the above table, in the tires of the examples and the reference examples provided with the spiral belt layer using the steel wire satisfying the conditions according to the present invention, the riding comfort and the turning performance are improved while ensuring fatigue. It is clear that

DESCRIPTION OF SYMBOLS 11 Tread part 12 Side wall part 13 Bead part 21 Bead core 22 Carcass layer 23 Spiral belt layer

Claims (8)

A steel wire is provided with a reinforcing layer formed by spirally winding a steel wire in the tire circumferential direction,
The steel wire rod, one strand that is typed or a non-twisted cord Do that from a bundle of two wires that are typed,
The steel wire has an elongation of 1.8 to 2.4% at a tension of 1000 MPa with a rubber attached,
The steel wire has a strand diameter of 0.30 to 0.34 mm, and
A pneumatic tire characterized in that a strength Ts defined by T / S with respect to breaking strength T (N) and cross-sectional area S (m ² ) of the steel wire is 2500 MPa.   The pneumatic tire according to claim 1, wherein the steel wire is made of high carbon steel having a carbon content of 0.8 to 1.0 mass%. The pneumatic tire according to claim 1 or 2, wherein the steel wire is a bundle of two strands that are spirally shaped.   The reinforcing layer passes a plurality of the steel wire rods wound on separate reels through a single base, and is then covered with rubber to obtain an intermediate material of the rubber composite. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is formed by winding.   The reinforcing layer passes a plurality of the steel wire rods wound on separate reels through one slit, and then presses rubber from above and below to obtain an intermediate material of the rubber composite, and the intermediate material is molded into a tire. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is formed by being wound in a process.   After the reinforcing layer has been molded with respect to the strands, the molded strands are covered with rubber without winding the molded strands, and the rubber-coated strands are tired. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is formed by being wound in a molding step.   The pneumatic layer according to claim 6, wherein the reinforcing layer is formed by covering the molded wire with rubber and then winding it in a tire molding process without winding the rubber-coated wire. tire.   It is a tire for motorcycles, The pneumatic tire as described in any one of Claims 1-7.

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