JP2014152431A - Method for manufacturing wire for reinforcing rubber article, and wire for reinforcing rubber article and rubber article obtained by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a wire for reinforcing a rubber article, on being especially applied to a tire, capable of making the tire further have a light weight, without causing faults such as wire crease, etc., and also without damaging various performances of the tire such as driving stability, etc., by compatibly attaining processability and strength of a flat wire, and to provide a wire for reinforcing a rubber article and a rubber article obtained by the method.SOLUTION: The method for manufacturing a wire for reinforcing a rubber article includes: a step of drawing a wire in which a wire-drawing processing is applied to a wire consisting of high-carbon steel having a carbon content of 1.00 mass% or more to have a circular cross section; and a step of processing in which processing members having a flat surface as a processing surface are brought into contact with the wire to which the wire-drawing processing has been applied from the vertical direction to process the wire to have a flat cross section.

Description

  The present invention relates to a method for producing a rubber article reinforcing wire, a rubber article reinforcing wire (hereinafter, also simply referred to as “manufacturing method” and “wire”) and a rubber article obtained by the method, and more particularly, mainly a rubber article such as a tire. The present invention relates to a method for producing a wire for reinforcing a rubber article applied to the above, a wire for reinforcing a rubber article obtained thereby, 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 lightweight pneumatic radial tire that eliminates problems in various tire performances such as peeling at the belt end, deterioration in handling stability, and occurrence of belt breakage.

JP 2011-25595 A

  However, although Patent Document 1 refers to the tensile strength of the wire, there is a concern that the ductility of the high carbon steel having a carbon content that has been conventionally used is lowered.

  Accordingly, an object of the present invention is to solve the above-mentioned problems and to make the workability and strength of the flat wire compatible, and particularly when applied to a tire, without causing problems such as wire breakage and stable handling. An object of the present invention is to provide a method for producing a wire for reinforcing a rubber article that can further reduce the weight of the tire without impairing various performances of the tire such as property, and a wire for reinforcing a rubber article and a rubber article obtained thereby.

  As a result of intensive studies on the steel material component, the flat cross-sectional shape and the strength of the wire, the present inventors have found that the above-described problems can be solved by adopting the following configuration. It came to be completed.

  That is, the method of manufacturing a wire for reinforcing rubber articles according to the present invention includes a wire drawing step of drawing a wire made of high carbon steel having a carbon content of 1.00% by mass or more into a circular cross section, and a wire drawing process. And a processing step of processing the wire into a flat cross section by bringing a processed member having a flat processing surface into contact with the formed wire from above and below.

The rubber article reinforcing wire of the present invention is a rubber article reinforcing wire obtained by the production method of the present invention,
Having a track-shaped flat cross section composed of a pair of parallel straight lines and a pair of opposing arcs protruding outwards;
When the thickness is T (mm), the width is W (mm), the radius of curvature of the arc is R (mm), and the tensile strength is TS (MPa), the following formulas (1) to (4),
3.0 ≦ W / T ≦ 8.0 (1)
0.325 × (W / T) ^−0.3416 ≦ T ≦ 0.343 × (W / T) ^−0.2549 (2)
0.6354 × T ≦ R ≦ 0.77 × T + 0.019 (3)
3300 ≦ TS ≦ 4000 (4)
It is characterized by satisfying the relationship represented by

  Furthermore, 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.

  According to the present invention, the above configuration makes it possible to achieve both workability and strength of the flat wire, and in particular, when applied to a tire, without causing problems such as wire breakage and stable handling. It has become possible to realize a method for producing a rubber article reinforcing wire that can further reduce the weight of the tire without impairing various tire performances such as properties, and a rubber article reinforcing wire and a rubber article obtained thereby. . 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 a rubber article, that is, peeling resistance and handling stability of the belt end. It is possible to improve various performances such as belt folding resistance.

It is width direction sectional drawing which shows an example of the wire for rubber article reinforcement of this invention. It is a graph which shows the relationship between thickness T and W / T in this invention. It is a graph which shows the relationship between thickness T and circular-arc curvature radius R in this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the method for producing a rubber article reinforcing wire of the present invention, a rubber article reinforcing wire is produced using a wire made of high carbon steel having a carbon content of 1.00% by mass or more. That is, first, the high carbon steel wire is drawn into a circular cross section (drawing process), and then a processed member having a flat processing surface is brought into contact with the wire from above and below to make the wire a flat cross section. It is characterized in that it is processed (processing step).

  As a method for increasing the strength of steel, there are a method of using hardening due to processing strain and a method of increasing the hardness of the material itself. In the present invention, a high-strength steel wire is formed by the latter method. To get. In the former method, the ductility of the material is impaired, but in the latter method, the processing strain can be reduced, so that the ductility is ensured. Specifically, in the present invention, high carbon steel having a carbon content as high as 1.00% by mass or more is used in order to increase the hardness of the material itself. This makes it possible to set a small amount of hardening due to processing strain when the wire is drawn into a circular cross section, so that ductility can be ensured in the wire of the intermediate material, and the wire to be subsequently applied after the wire drawing processing can be made into a flat cross section. During the processing, it is possible to prevent the wire from cracking. That is, if a wire with a low carbon content is used to obtain a predetermined high-strength flat wire, it is necessary to sacrifice ductility (workability). According to the present invention, a high-strength flat wire can be obtained while ensuring ductility, that is, while suppressing the occurrence of processing defects. When the carbon content is less than 1.00% by mass, it is difficult to ensure a certain degree of high strength, which is particularly suitable as a tire reinforcing belt while ensuring ductility. On the other hand, if the carbon content is too high, heat treatment prior to wire drawing becomes difficult and causes a decrease in productivity and a decrease in ductility. Therefore, the upper limit value of the carbon content is preferably 1.20% by mass or less. . Here, the processing member in the present invention may be a tool generally used for wire processing, and examples thereof include a rolling roller and a die.

  FIG. 1 is a cross-sectional view in the width direction showing an example of a wire for reinforcing a rubber article of the present invention. The wire for reinforcing rubber articles 1 of the present invention is obtained by the above-described manufacturing method of the present invention. As shown in the figure, a pair of parallel straight lines 11 and a pair of arcs 12 which protrude outward and face each other. The track has a flat cross section.

In the wire of the present invention, the thickness T (mm) and the width W (mm) are expressed by the following formula (1),
3.0 ≦ W / T ≦ 8.0 (1)
It is necessary to satisfy the relationship expressed by When W / T is less than 3.0, the thickness T is increased in order to ensure the strength when used as a tire reinforcing belt, which is disadvantageous in reducing the weight of the tire. On the other hand, in a high flatness rolling process in which W / T exceeds 8.0, cracks are likely to occur in the wire.

Moreover, in the wire of this invention, thickness T (mm) and width W (mm) are following formula (2),
0.325 × (W / T) ^−0.3416 ≦ T ≦ 0.343 × (W / T) ^−0.2549 (2)
It is necessary to satisfy the relationship expressed by FIG. 2 is a graph showing the relationship between the thickness T and W / T in the present invention. When the thickness T is less than 0.325 × (W / T) ^−0.3416, it is necessary to increase the tensile strength of the metal wire in order to ensure the strength of the tire as a reinforcing belt, which makes manufacture difficult. . On the other hand, if the thickness T exceeds 0.343 × (W / T) ^−0.2549 , the wire surface distortion 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. End up.

Furthermore, in the wire of the present invention, the curvature radius R (mm) of the arc 12 constituting the flat cross section of the wire 1 is expressed by the following formula (3),
0.6354 × T ≦ R ≦ 0.77 × T + 0.019 (3)
It is necessary to satisfy the relationship expressed by FIG. 3 is a graph showing the relationship between the thickness T and the arc curvature radius R in the present invention. When the radius of curvature R (mm) of the arc is less than 0.6354 × T (mm), the radius of curvature is too small, so that the shear stress generated at the bonding interface between the wire and rubber is locally increased, resulting in separation. It becomes easy. On the other hand, when the radius of curvature R (mm) exceeds 0.77 × T + 0.019 (mm), the shear stress generated at the bonding interface between the wire and the rubber is locally present in the boundary region between the linear portion and the arc portion of the wire. And the separation tends to occur.

Furthermore, in the wire of the present invention, the tensile strength TS (MPa) is expressed by the following formula (4),
3300 ≦ TS ≦ 4000 (4)
It is necessary to satisfy the relationship expressed by If the tensile strength is less than 3300 MPa, the amount of metal wire used increases in order to ensure the strength of the reinforcing belt for the tire, which is disadvantageous for weight reduction of the tire. Alternatively, it is necessary to increase the number of driven wires, and the interval between adjacent wires becomes narrow, so that the occurrence and propagation of separation at the belt end cannot be suppressed. On the other hand, a wire having a tensile strength exceeding 4000 MPa is difficult to manufacture and is not suitable for mass production.

  In the present invention, a high carbon steel wire obtained by the manufacturing method of the present invention described above and having a track-shaped flat cross section comprising a pair of parallel straight lines and a pair of arcs that protrude outward and face each other. The thickness T, the width W, the radius of curvature R of the arc, and the tensile strength TS satisfy the relationships represented by the above formulas (1) to (4), so that the desired effect of the present invention described above can be obtained. It has been found that it can be obtained. Since the wire of the present invention has good flat workability, the conventional equipment and process for producing a wire having a normal circular cross section is used as it is, and rolling is performed between rollers in the latter half of the wire drawing. Or by flattening by passing a flat hole die or the like, it can be economically and easily manufactured. In addition, when the wire of the present invention is applied to a tire, it is possible to suppress the occurrence of a failure caused by the belt, particularly when used for a belt.

  The rubber article of the present invention may be any rubber article in which the above-described 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 tires are particularly tires. In the 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.

  In the present invention, in this case, it is preferable to align 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 for 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 in more detail with reference to 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. Steel belts shown in the following table were applied to the belt layers. In the following table, the track shape means a flat cross-sectional shape composed of a pair of parallel straight lines 11 and a pair of arcs 12 that protrude outward and face each other (see FIG. 1). Such a track-shaped wire is manufactured by drawing a wire into a circular cross section and then contacting the wire with a processing member having a flat processing surface from above and below to process the wire into a flat cross section. did. Such track-shaped wires were used by being aligned in parallel so that the width direction thereof is the in-plane direction of the belt ply.

<Presence / absence of cracks during flattening>
In the process of processing the wire from a circular cross section into a flat cross section having a predetermined thickness, the presence or absence of cracks in the cross section of the wire was confirmed.

<Belt folding resistance>
Each test tire is mounted on an actual vehicle, and after a foldable road running at 20,000 km at a speed of 60 km per hour, the test tire is dissected and the wires in the belt layer are collected and broken. The number of wires in the wire was investigated, and the reciprocal number was indexed with the tire of Comparative Example 1 as 100. It shows that it is excellent in belt folding resistance, so that this index value is large.

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

<Steering stability test>
Each test tire adjusted according to JIS standard D4202 was installed in a drum testing machine having an outer diameter of 3 m, loaded with a load determined from a predetermined size and internal pressure, and preliminarily run at a speed of 30 km / h for 30 minutes. In order to eliminate the influence of the increase in internal pressure due to temperature rise, the internal pressure was readjusted to the standard value excluding the load. After that, again with the same speed and the same load, the slip angle is continuously added every 1 ° from ± 1 ° to ± 4 °, and the cornering force (CF) per unit angle at each positive and negative angle is measured. The cornering power (CP) was obtained by calculating the average value of these. The results were expressed by dividing the CP of each test tire by the CP of the tire of Comparative Example 1 and indexing it. The larger this index, the better the steering stability.

<Belt weight>
The weight per unit area of the belt layer used for each test tire was measured, and Comparative Example 1 was set as 100 and indicated as an index. It can be said that the smaller this value is, the lighter and lighter the belt layer is.

  As shown in the above table, each of the examples having a track-shaped flat cross section satisfying a predetermined condition manufactured using a wire made of high carbon steel having a carbon content of 1.00% by mass or more. In the wire for reinforcing rubber articles, good performance has been obtained in all of belt folding resistance, BES resistance and steering stability without cracking during flattening, and weight reduction has been achieved. You can see that

  On the other hand, in Comparative Examples 2 and 4, cracks occurred during flattening due to the low carbon content, and in Comparative Example 3, the tensile strength TS was low, resulting in insufficient wire strength and an increased number of implantations. As a result, the BES resistance is lowered due to the narrower code gap. Further, in Comparative Example 5, the BES resistance is lowered because the radius of curvature R of the arc is small, and in Comparative Example 6, since the wire is thin, cracks are generated during flattening. Further, in Comparative Example 7, the resistance to belt folding is reduced because the wire is thick, and in Comparative Example 8, the tensile strength TS is high, and thus cracks occur during flattening. Furthermore, in Comparative Example 9, since the radius of curvature R of the arc is large, the BES resistance is lowered. In Comparative Example 10, since the flatness ratio of the wire is large, cracks are generated during flattening.

DESCRIPTION OF SYMBOLS 1 ... Rubber article reinforcement wire, 11 ... Linear part, 12 ... Arc part, T ... Wire thickness, W ... Wire width, R ... Wire arc part curvature radius

Claims (4)

  A wire drawing step of drawing a wire made of high carbon steel having a carbon content of 1.00% by mass or more into a circular cross section, and a processed member having a flat processing surface with respect to the drawn wire And a processing step of processing the wire into a flat cross section by bringing the wire into contact with each other in the vertical direction. A rubber article reinforcing wire obtained by the manufacturing method according to claim 1,
Having a track-shaped flat cross section composed of a pair of parallel straight lines and a pair of opposing arcs protruding outwards;
When the thickness is T (mm), the width is W (mm), the radius of curvature of the arc is R (mm), and the tensile strength is TS (MPa), the following formulas (1) to (4),
3.0 ≦ W / T ≦ 8.0 (1)
0.325 × (W / T) ^−0.3416 ≦ T ≦ 0.343 × (W / T) ^−0.2549 (2)
0.6354 × T ≦ R ≦ 0.77 × T + 0.019 (3)
3300 ≦ TS ≦ 4000 (4)
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 2 as a reinforcing material.   The rubber article according to claim 3, 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.

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