JP2009249763A - Wire for reinforcing rubber article and rubber article using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire for reinforcing a rubber article, capable of further reducing the weight of a tire without causing deficiency such as break of the wire and without damaging various properties of the tire such as steering stability especially when applied for a tire, and to provide the rubber article using the wire. <P>SOLUTION: The wire 1 for reinforcing the rubber article, having a truck-shaped flat cross-section composed of a pair of parallel linear parts 11, a pair of arc parts (a) facing to the outside thereof in convex shapes, and arc parts (b) at the sites changing from the linear parts 11 to the arc parts (a) satisfies the relations represented by the following expressions (1) to (3): 0.15≤T≤0.30 (1); 0.5×T≤Ra≤0.77×T+0.019 (2); and T≤Rb≤2.5×T (3) [wherein, T (mm) is a thickness of the wire; Ra (mm) and Rb (mm) are radii of curvatures of the arc parts]. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber article reinforcing wire (hereinafter, also simply referred to as “wire”) and a rubber article using the same, and more particularly to achieve weight reduction without impairing various performances of a tire as a rubber article. The present invention relates to a rubber article reinforcing wire and a rubber article using the same.

  In recent years, there has been an increasing demand for weight reduction of tires in order to improve the fuel efficiency of automobiles. On the other hand, steel cords used for tire reinforcement belts have been reviewed as an effective means for weight reduction, and various new technologies for their structures have been proposed. For example, Patent Document 1 discloses a technique using a belt cord in which a metal single wire is spirally corrugated in advance to have a predetermined damping ratio, thereby reducing the weight of the tire and improving the ride comfort. It is described that it is possible to prevent the deterioration of the above.

  Further, Patent Document 2 discloses that weight reduction of a tire and reduction of rolling resistance are achieved while suppressing end peeling and cord breakage of a belt and maintaining various tire performances such as ride comfort and steering stability. For the purpose of the above, at least most of the metal wires in the belt ply are arranged in parallel in the belt width direction without twisting one or more flat metal wires that are long in the belt ply width direction or It exists as a metal wire bundle, and this metal single wire or metal wire bundle is arranged in parallel in the belt width direction in parallel with the belt width direction with a space between the single wires or between the bundles, and is embedded in rubber to form a belt layer A pneumatic radial tire is disclosed.

Furthermore, as a technique related to the improvement of the flat wire applied to the reinforcing layer of the tire, Patent Document 3 includes a pair of flat portions and a pair of curved portions formed by flattening the round wire, A flat wire for reinforcing rubber is disclosed in which the edge angle θ of the portion transitioning from the flat portion to the curved portion in the projection field of view is in the range of 142 ° to 163 °.
JP-A-11-91311 (Claims etc.) JP 2001-328407 A (Claims etc.) JP 2006-336154 A (Claims etc.)

  However, since the strand diameter of the belt cord used in Patent Document 1 is as thick as 0.40 to 0.50 mm, a large strain is generated on the surface of the metal wire when bending deformation is repeatedly applied during running. There has been a problem that the metal wire is easily broken when a large bending deformation is applied when traveling on a rough road, and improvement has been demanded. Further, although there is a technique as disclosed in Patent Document 2, a reinforcing material that can be further reduced in weight without impairing various performances of the tire, particularly when applied to a tire, by improving the reinforcing material side. It was required to be realized.

  Accordingly, an object of the present invention is to solve the above-described problems and to further improve the tire without causing problems such as wire breakage and without impairing various tire performances such as steering stability when applied to a tire. An object of the present invention is to provide a wire for reinforcing a rubber article that can be reduced in weight, and a rubber article using the same.

  As a result of intensive studies on the cross-sectional shape of the rubber article reinforcing wire, the present inventor has found that the above problem can be solved by using a wire having a specific flat cross-sectional shape as a reinforcing material, and to complete the present invention. It came.

That is, the wire for reinforcing rubber articles of the present invention transitions from a pair of parallel straight portions, a pair of arc portions a that protrude outward from the pair, and from the straight portions to the arc portion a. In the wire for reinforcing a rubber article having a track-shaped flat cross section having a circular arc part b at a site,
When the thickness of the wire is T (mm), the radius of curvature of the arc portion a is Ra (mm), and the radius of curvature of the arc portion b is Rb (mm), the following formulas (1), (2) and (3),
0.15 ≦ T ≦ 0.30 (1)
0.5 × T ≦ Ra ≦ 0.77 × T + 0.019 (2)
T ≦ Rb ≦ 2.5 × T (3)
It is characterized by satisfying the relationship represented by

  The rubber article of the present invention is characterized in that the rubber article reinforcing wire of the present invention is used as a reinforcing material. In the rubber article of the present invention, it is preferable that the rubber article reinforcing wires are aligned in parallel so that the width direction thereof is the in-plane direction of the rubber article. The pneumatic tire of the present invention is characterized by using the rubber article reinforcing wire of the present invention.

  According to the present invention, the above configuration makes the tire even lighter without causing problems such as wire breakage and without impairing various tire performances such as steering stability, particularly when applied to a tire. It is possible to realize a wire for reinforcing a rubber article that can be made into a rubber article and a rubber article using the same. Therefore, according to the pneumatic radial tire as an example of the rubber article of the present invention, there are various problems when using a conventional flat wire for reinforcing rubber articles, that is, peeling resistance and handling stability at the belt end. It is possible to improve various performances such as belt folding resistance.

Hereinafter, preferred embodiments of the present invention will be described in detail.
In FIG. 1, sectional drawing of an example of the wire for rubber article reinforcement of this invention is shown. As shown in the drawing, the wire for reinforcing rubber articles 1 of the present invention includes a pair of parallel straight portions 11, a pair of arc portions a that are convex and opposed to each other, and a further arc portion from the straight portions 11. It has a track-shaped flat cross section having a circular arc part b at a portion transitioning to a.

In the present invention, the thickness T (mm) of the wire is expressed by the following formula (1),
0.15 ≦ T ≦ 0.30 (1)
It is necessary to satisfy the relationship represented by the formula, and preferably 0.18 ≦ T ≦ 0.24. If the thickness T is less than 0.15 mm, the rigidity of the rubber article is insufficient, and when used as a tire reinforcing belt, steering stability is impaired. On the other hand, when the thickness T exceeds 0.30 mm, the surface distortion of the wire becomes large at the time of large bending deformation, and the wire is likely to be broken at the time of applying the tire or sudden turning of the vehicle.

In the present invention, the radius of curvature Ra of the arc part a of the wire is expressed by the following formula (2),
0.5 × T ≦ Ra ≦ 0.77 × T + 0.019 (2)
It is necessary to satisfy the relational expression expressed by If the radius of curvature Ra (mm) of the arc is less than 0.5 × T (mm), the radius of curvature is too small, and the shear stress generated at the bonding interface between the wire and the rubber is locally increased, and separation is likely to occur. Become. On the other hand, when the curvature radius Ra (mm) exceeds 0.77 × T + 0.019 (mm), the shear stress generated at the bonding interface between the wire and the rubber is locally large in the boundary region with the arc part b of the wire. As a result, separation is likely to occur.

Furthermore, in this invention, the curvature radius Rb of the circular arc part b of a wire is the following formula (3),
T ≦ Rb ≦ 2.5 × T (3)
It is necessary to satisfy the relational expression expressed by When the radius of curvature Rb (mm) of the arc is less than T (mm), the radius of curvature is too small, so that the local distortion of the wire arc part b becomes large at the time of large bending deformation, so Folding easily occurs. On the other hand, when the curvature radius Rb (mm) exceeds 2.5 × T (mm), the shear stress generated at the bonding interface between the wire and the rubber locally increases in the boundary region with the arc part a of the wire. Separation is likely to occur. In addition, in the boundary region with the straight portion 11 of the wire, the strain generated at the time of large bending deformation is locally increased, and the wire is likely to be broken at the time of sudden turning of the vehicle.

  In the present invention, a pair of parallel straight portions 11, a pair of arc portions a that are convex and opposed to each other, and a circular arc portion b at a portion that transitions from the straight portions 11 to the arc portion a. The wire having a track-shaped flat cross section having the thickness T and the radii of curvature Ra and Rb of the arc portions a and b satisfy the above formulas (1) to (3). It has been found that the effects of the period can be obtained, and other specific wire materials and the like are not particularly limited. Such a wire of the present invention can be rolled between rollers in the latter half of the wire drawing process using a conventional equipment and process for producing a wire having a normal circular section, or a flat hole die. By flattening it by passing it through, etc., it can be manufactured economically and simply.

  Further, the rubber article of the present invention may be any one as long as the wire for reinforcing a rubber article of the present invention is used as a reinforcing material, and thereby the desired effect of the present invention can be obtained. Examples of the rubber article of the present invention include tires and industrial belts, and particularly, pneumatic tires. In the pneumatic tire as an example of the rubber article of the present invention, as described above, it is possible to reduce the weight without impairing the various performances of the tire and without causing defects due to the wire. Become.

  In this case, it is preferable to arrange the wires 1 in parallel so that the width direction thereof is the in-plane direction of the rubber article. Thereby, the thickness of the rubber article can be reduced, which is excellent in terms of weight reduction. For example, when the wire 1 is used as a tire reinforcing belt, the wire 1 may be arranged so that the width direction of the wire 1 is aligned in the in-plane direction of the belt.

Hereinafter, the present invention will be described specifically by way of examples.
A pneumatic radial tire (size 175 / 70R14) as an example of a rubber article is composed of a first belt ply inclined at an angle of 20 ° to the right with respect to the tire equator plane and a second belt ply inclined at an angle of 20 ° to the left. A steel wire shown in Tables 1 to 3 below was applied to each belt layer. In the following table, the track shape refers to a pair of parallel straight portions 11, a pair of arc portions a that are convex and opposed to each other, and a portion that transitions from the straight portions 11 to the arc portion a. A flat cross-sectional shape (see FIG. 2) having a flat cross-sectional shape (see FIG. 1) having a portion b and a pair of parallel straight portions 21 and a pair of arc portions a that are convex and opposed to the outside. ). The track-shaped wires were used by being aligned in parallel so that the width direction thereof was the in-plane direction of the belt ply.

  The performance test shown below was carried out for each test tire. The results are also shown in Tables 1 to 3 below in terms of an index that is a relative evaluation when the performance of the tire using the circular cross-section wire of Comparative Example 1 is taken as 100. Moreover, the relationship between the thickness T of the wire of Examples 1-5 and Comparative Examples 2-7 and the curvature radius Ra of the circular arc part a is shown in the graph of FIG. The relationship between the wire thickness T and the radius of curvature Rb of the arc portion b in Examples 1 to 5 and Comparative Examples 2 to 7 is shown in the graph of FIG. The relationship between the wire thickness T and the radius of curvature Ra of the arc portion a in Comparative Examples 8 to 12 is shown in the graph of FIG.

<Belt-end separation (end peeling) test>
Each test tire is assembled on a regular rim, filled with an internal pressure of 147 kPa (1.5 kgf / cm ² ), mounted on a test passenger car, run on a general road for 60,000 km, and then the tire is dissected to belt The length of the crack generated at the edge of the film was measured. The reciprocal of the crack length of each test tire was calculated and indicated by an index with the reciprocal value of the test tire of Comparative Example 1 being 100. The larger this value, the better the belt end separation resistance.

<Steering stability>
A test tire adjusted according to JIS standard D4202 was placed in a drum testing machine having an outer diameter of 3 m, a load determined from a predetermined size and an internal pressure was applied, and the tire was preliminarily run at a speed of 30 km / h for 30 minutes. . After that, to eliminate the increase in internal pressure due to temperature rise, readjust the internal pressure to the standard value excluding the load, and then positive / negative the slip angle again from ± 1 ° to ± 4 ° under the same speed and the same load. The cornering force (CF) per unit angle at each positive and negative angle was measured, and the average value was calculated to obtain the cornering power (CP). The CP of each test tire was divided by the CP of the tire of Comparative Example 1 and displayed as an index. The larger this value, the better the steering stability.

<Belt folding resistance>
Each test tire is mounted on an actual vehicle, and it is folded in a state where it bends at a constant speed and travels 20,000 km at a speed of 60 km / h, then the test tire is dissected and the wires in the belt layer are collected and folded. The number of wires was examined, and the reciprocal number was displayed as an index with the tire of Comparative Example 1 as 100. It shows that it is excellent in belt bending resistance, so that this index value is large.

  As shown in Tables 1 to 3, in the test tire of Comparative Example 2, since the wire thickness T is too thin, the rigidity of the rubber article is insufficient, and the steering stability is impaired. In the test tire of Comparative Example 3, since the radius of curvature Ra of the arc portion a of the wire is too large, the shear stress generated at the bonding interface between the wire and rubber in the boundary region with the radius of curvature Rb of the arc portion b of the wire Becomes locally large and the separation property is inferior. In the test tire of Comparative Example 4, since the radius of curvature Ra of the arc portion a of the wire is too small, the shear stress generated at the bonding interface between the wire and the rubber is locally increased, resulting in poor separation. . In the test tire of Comparative Example 5, since the radius of curvature Rb of the arc part b of the wire is too small, the local distortion of the wire arc part b becomes large at the time of large bending deformation, and the wire is used when the vehicle turns suddenly. It is easy for folds to occur. Further, in the test tire of Comparative Example 6, the radius of curvature Rb of the arc part b of the wire is too large, so that the shear stress generated at the bonding interface between the wire and the rubber in the boundary region with the arc part a of the wire is large. Thus, the separation property is inferior, the strain generated at the time of large bending deformation in the boundary region with the straight portion 11 of the wire is locally increased, and the wire is likely to be broken at the time of sudden turning of the vehicle. ing. Furthermore, since the test tire of Comparative Example 7 has a too thick wire, the surface strain of the wire becomes large at the time of large bending deformation, and the wire is likely to be broken at the time of sudden turning of the vehicle. ing.

  Furthermore, in the test tires of Comparative Examples 8 to 12, since there is no arc portion b shown in FIG. 1 due to the wire cross-sectional shape shown in FIG. 2, the wire transition from the wire straight portion 21 to the arc portion a during large bending deformation. It can be seen that the local distortion of the portion to be increased increases, and the wire is easily broken when the vehicle turns suddenly.

  On the other hand, in the test tires of Examples 1 to 5 according to the present invention, the thickness T of the flat wire and the curvature radii Ra and Rb of the arc portions a and b are optimized, respectively. It was confirmed that both the handling stability and the belt bending resistance were improved as compared with Comparative Example 1 using a round wire having a circular cross section.

It is sectional drawing which shows an example of the wire for rubber article reinforcement of this invention. It is sectional drawing which shows an example of the wire for rubber article reinforcement of Comparative Examples 8-12. It is sectional drawing which shows the conventional round wire. It is a graph which shows the relationship between the thickness T of the wire in Examples 1-5 and Comparative Examples 2-7, and the curvature radius Ra of a circular arc. It is a graph which shows the relationship between the thickness T of the wire in Examples 1-5 and Comparative Examples 2-7, and the curvature radius Rb of a circular arc. It is a graph which shows the relationship between the thickness T of the wire in Comparative Examples 8-12, and the curvature radius Ra of a circular arc.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rubber article reinforcement wire of this invention 2 Rubber article reinforcement wire of comparative example 3 Round wire 11 Straight line part 21 of rubber article reinforcement wire of this invention Straight line part a of rubber article reinforcement wire of comparative example This invention and Arc part b of radius of curvature Ra of rubber article reinforcing wire of Comparative Examples 8 to 12 Arc part T of radius of curvature Rb of rubber article reinforcing wire of the present invention Wire thickness W Wire width Ra Wire radius of curvature of wire arc part a Rb Curvature radius of wire arc b

Claims (4)

A track-like shape having a pair of parallel straight portions, a pair of arc portions a that are convex and opposed to each other, and an arc portion b at a portion that transitions from the straight portions to the arc portion a. In the wire for reinforcing rubber articles having a flat cross section,
When the thickness of the wire is T (mm), the radius of curvature of the arc portion a is Ra (mm), and the radius of curvature of the arc portion b is Rb (mm), the following formulas (1), (2) and (3),
0.15 ≦ T ≦ 0.30 (1)
0.5 × T ≦ Ra ≦ 0.77 × T + 0.019 (2)
T ≦ Rb ≦ 2.5 × T (3)
A wire for reinforcing rubber articles characterized by satisfying the relationship represented by:   A rubber article comprising the wire for reinforcing a rubber article according to claim 1 as a reinforcing material.   The rubber article according to claim 2, wherein the rubber article reinforcing wires are aligned in parallel so that a width direction thereof is an in-plane direction of the rubber article.   The rubber article according to claim 2 or 3, which is a pneumatic tire.

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