JPH0594297U - Steel cord for reinforcing rubber products - Google Patents

Abstract

(57) [Summary] [Purpose] A rubber material infiltration path is provided in the void of the wire approximately in the center of the outer wire to greatly improve the rubber infiltration property and to achieve a complete composite with the rubber material. It is intended to provide a steel cord for reinforcing a rubber product which is a body. [Structure] Nine wires having the same wire diameter (d ₂ ) are arranged around three wires having the same wire diameter (d ₁ ), and these 12 wires are placed in the same direction and at the same pitch. In a steel cord for reinforcing rubber products having a 1 × 12 structure formed by twisting together, the wire diameter ratio of the above-mentioned three wires and nine wires is d ₁ / d ₂ =
1.02 to 1.25, and at least one of the three strands has a peculiar pitch P ₁ = 4d _{1 to} 35d ₁ and an apparent outer diameter d ₀ = 1.08d _{1 to} 1.5d _1. It is a steel cord for reinforcing rubber products that has a small spiral habit that makes it possible to prevent the steel cord from deteriorating in strength due to fretting phenomenon, separation phenomenon and corrosion.
Moreover, the manufacturing cost is reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rubber product reinforcing steel cord used as a reinforcing material for rubber products such as automobile tires and conveyor belts.

[0002]

[Prior Art]

 In general, this type of steel cord is used as a reinforcing material for rubber products such as automobile tires and conveyor belts by covering a large number of them in parallel with each other and covering them with rubber material.

As a steel cord that reinforces a conventional rubber product, for example, a pneumatic radial tire for heavy load, as shown in FIG. 4A, nine strands are arranged around three strands arranged in the substantially center. A steel cord having a polygonal cross section, in which twelve strands 6 having the same wire diameter are densely twisted in the same direction at the same pitch and densely, a so-called 1 × 12 structure steel cord 5 is known. ing.

Further, as a steel cord having the same number of strands as the steel cord 5, as shown in FIG. 4B, the above-mentioned strand is formed around a strand 9 composed of three strands 8 densely twisted together. A so-called 3 + 9 structure steel cord 7 in which nine strands 10 are densely twisted in a direction or pitch different from the twist is also known.

The steel cord 5 having the 1 × 12 structure can be produced in one twisting process, whereas the steel cord 7 having the 3 + 9 structure requires two twisting processes. The production time can be shortened without owning a large number of line facilities, and the production cost can be reduced.

However, in the steel cord 5, since the adjacent wires 6 and 6 are close to each other or extremely close to each other, the rubber material penetrates into the inside from between the wires 6 and 6 at the time of molding a rubber product. This was not possible, and it was not possible to form a composite with a perfect rubber by merely covering the outer peripheral portion of the cord. Therefore, in the tire using the steel cord 5, the cord and the rubber material are not sufficiently adhered to each other, so that the cord and the rubber material are separated from each other when the vehicle is running, that is, a so-called separate phenomenon occurs, or the tire is adjacent to each other. A part of the cord may break due to the fretting phenomenon caused by the contact between the wires. Further, the water content in the rubber and the water content that has penetrated from the cuts in the tire reach the void D formed by being surrounded by the adjacent strands, propagate in the longitudinal direction of the cord, and cause rust to occur throughout the steel cord. It was also the cause of the drastic reduction in the mechanical strength of.

In view of the above circumstances, various steel cords having a twisted structure of this kind have been proposed in recent years so that a rubber material can be expected to sufficiently penetrate into the cord.

For example, as shown in FIG. 5, the steel cord 13 disclosed in Japanese Patent Laid-Open No. 62-41339 has a wire diameter smaller than the above wire diameter around three wire wires 11 arranged at the substantially center. Nine strands 12 with a smaller diameter are arranged, twisted in the same direction and at the same pitch, and a gap C is provided between the strands 12 arranged around the inside. It is intended to sufficiently infiltrate the rubber material.

[0009]

[Problems to be solved by the device]

 However, the steel cord 13 also has a void D at the substantially center of the three strands 11 arranged substantially at the center, and it is not possible to achieve the desired infiltration of the rubber material. Therefore, the above-mentioned various problems are brought about. The present invention has been made in view of the above problems, and it has a rubber infiltration path communicating from the outer circumference of the cord to the central space to greatly improve the infiltration property of the rubber material to achieve a complete compounding with the rubber material. It is an object to provide a steel cord for reinforcing a rubber product which is a united body.

[0010]

Means for Solving the Problems In order to achieve the above object, a steel cord for reinforcing a rubber product according to the present invention has nine identical wires around a wire having three identical wire diameters (d ₁ ). In a steel cord for reinforcing rubber products having a 1 × 1 2 structure, in which strands having a diameter (d ₂ ) are arranged and these 12 strands are twisted in the same direction and at the same pitch, the above 3 strands are used. When 9 lines of wire diameter ratio is d ₁ / d ₂ = 1.02~1.25, and three of the at least one habit pitch P ₁ = 4d ₁ ~ of the diameter of the wire It has a small spiral habit of 35d ₁ and an apparent outer diameter d ₀ = 1.08 d _{1 to} 1.5d ₁ .

By the way, the above-mentioned various numerical limits are determined based on the results obtained from many experiments, and the outline thereof is as follows. The wire diameter ratio d ₁ / d ₂ = 1.02 to 1.25 of the three wires and the nine wires is set so that when the wire diameter ratio is smaller than 1.02, the gap C between the wires is C. This is because the width of the rubber is reduced, and it is not possible to expect the desired penetration of the rubber material, and when it is larger than 1.25, the shape is deteriorated and the core is ejected.

It is also possible to make the wire diameter ratio smaller than 1.02 and increase the apparent outer diameter d ₀ , but in this case, the spiral shape is small due to the tension applied to the steel cord during molding as a rubber product. It is not a good idea because the habit will be easily deformed and it will be difficult to penetrate rubber.

Further, if the peculiarity pitch P ₁ is made smaller than 4 times d ₁ , the strand will be subjected to an unreasonable plastic deformation during the peculiar working of the strand, and the strand will be easily broken and the productivity will be reduced. On the other hand, if it is more than 35 times, the gap between the strands is reduced due to the tensile force due to the flow of the rubber material at the time of molding the rubber product or the ironing force applied to the surface of the cord, resulting in insufficient penetration of the rubber material.

Further, when the apparent outer diameter d ₀ is smaller than 1.08 times d ₁ , the rubber material having sufficient fluidity can sufficiently penetrate into the steel cord during pressure vulcanization. On the other hand, if it is more than 1.5 times, the stability of the twist is deteriorated and the fatigue resistance is deteriorated.

It should be noted that the substantially spiral-shaped habit in the present invention does not need to be exactly spiral-shaped, and even if it is simply wavy, it exhibits the same effect as the spiral-shaped habit. Such shapes are also included.

[0016]

[Work]

When the steel cord configured as described above is sandwiched between two rubber sheets and pressure-vulcanized, the rubber material passes through the rubber intrusion passage of the minute gap formed between the strands and the rubber material is applied to the inner portion of the cord. Infiltrate into the to form a complete composite with rubber material, and prevent the strength of steel cord from being deteriorated due to fretting phenomenon, separation phenomenon and corrosion.

[0018]

【Example】

Hereinafter, the steel cord for reinforcing a rubber product of the present invention will be specifically described with reference to examples. (Example 1) In FIG. 1, nine strands 4 having the same wire diameter d ₂ are arranged around three strands 3 having the same wire diameter d ₁ , and these 12 strands are connected to each other. A steel cord having a 1 × 12 structure in which the strands are twisted in the same direction and at the same pitch, and one of the above three strands 2 has a small spiral habit. ing. With this structure, the three wires 2, 3 have a wire diameter d ₁ = 0.32 mm, the nine wires 4 have a wire diameter d ₂ = 0.30 mm, and a substantially spiral small pitch P ₁ = 4. .0 mm, the apparent outer diameter d ₀ = 0.46 mm, and the cord twist pitch P = 15 mm. _No. 8 of the experiment No. 8 in Table 1 is the same as Example ₁ in which d ₁ = 0.36 mm, d ₂ = 0.30 mm, P ₁ = 2.0 mm, d ₀ = 0.46 mm, and P = 15 mm. 9 shows.

Example 2 In FIG. 2, the structure is substantially the same as that of Example 1, but two of the three strands having the same wire diameter d ₁ have a substantially spiral shape. It has a small habit. With this configuration, the wire diameters d 3 of the three wires 2 and 3 are d ₁ = 0.31 mm, the wire diameter d of the nine wires 4 is d ₂ = 0.30 mm, and the pitch P ₁ of the small spiral p ₁ = 8. .0 mm, an apparent outer diameter d ₀ = 0.43 mm, and a cord twist pitch P = 15 mm. _No. 11 of Experiment No. 11 of Table 1 also shows d ₁ = 0.32 mm, d ₂ = 0.30 mm, P ₁ = 4.0 mm, d ₀ = 0.38 mm, and P = 15 mm. _No. 12 and also the experiment No. 1 of Table 1 in which d ₁ = 0.36 mm, d ₂ = 0.30 mm, P ₁ = 2.0 mm, d ₀ = 0.40 mm, and P = 15 mm. 13 shows.

Example 3 In FIG. 3, a point different from Examples 1 and 2 is that a steel cord in which all of the three strands 2 have a small spiral habit. Has been done. With this configuration, the wire diameter d of the three wires 2₁= 0.26 mm, the wire diameter of the nine wires 4 d₂= 0.25 mm, small spiral pitch P with a substantially spiral shape₁= 8.0 mm, apparent outer diameter d₀= 0.37 mm and cord twist pitch P = 12 mm. 15, also d₁= 0.28 mm, d₂= 0.25 mm, P ₁ = 4.0 mm, d₀= 0.35 mm, P = 12 mm. 16 and also d₁= 0.30 mm, d₂= 0.25 mm, P₁= 2.0 mm, d₀= 0.33 mm, P = 12 mm, the experimental NO. 17 shows.

An outline of the production of each of the steel cords will be described. It is sufficient to twist 12 strands at the same time by a known twisting device. In this case, the inner 3 strands and the outer 9 strands are twisted together. Since there is a case where the strands of one of the strands are replaced with each other and twisting may occur, it is advisable to twist the three strands of the inner side a little earlier and twist the strands so that nine strands are arranged on the outer periphery.

By the way, some spiral small habits of the inner three strands are rotated with the supplied strands as an axis, as shown in Japanese Patent Publication No. 63-63293. The curling device imparts a desired curl pitch P ₁ and outer diameter d ₀ . At this time, in order to impart a desired peculiar pitch P ₁ and an apparent outer diameter d ₀ , the intervals and dimensions of the pegs and the number of rotations of the strands about the strands are adjusted.

In the above embodiment, the wire diameter d ₂ of each wire 4 is preferably within the range of 0.15 to 0.40 mm. The reason is that if the wire diameter d ₂ is less than 0.15 mm, the strength of the steel cord is insufficient, and if it exceeds 0.40 mm, the flexibility is poor.

In addition, a steel wire having a carbon content of 0.70 to 0.90 wt% is usually used for the wire constituting the steel cord, but in order to give the steel cord 1 high strength and good toughness. It is preferable to use a steel wire having a carbon content of 0.80 to 0.85 wt% for each wire 4.

Further, in order to improve the adhesion between the rubber material and the steel cord 1, it is preferable to use brass wires having Cu and Zn as the main components, which are plated with brass.

Furthermore, in order to further improve the twisting stability of the steel cord 1, a single wire having a diameter smaller than that of the cord-constituting wire 4 (for example, 0.15 mm diameter) is provided around the steel cord 1. It is also possible to wrap.

Next, in order to confirm the performance characteristics of the steel cord of the present invention, a comparative test of the steel cord of the present invention described in the above-mentioned embodiment and a conventional steel cord was conducted, and the penetration of rubber material, salt water When the rubber adhesion coverage, fatigue resistance, fretting amount and handling workability were evaluated, the results shown in Table 1 were obtained.

It should be noted, in the NS table, the number of small shaping wire of spiral, d ₀ is the habit outer diameter, P ₁ Hakuse pitch, d ₁ is the three strands arranged substantially at the center The wire diameter, d ₂ is the wire diameter of the nine strands arranged around d ₁ . Further, RP represents the penetration rate of the rubber material, RC represents the salt water adhesive rubber coverage rate, RF represents the fatigue property, and CO represents the manufacturing cost.

[0029]

[Table 1]

In this evaluation, the infiltration rate RP (%) of the rubber material is 100% modulus of 35 Kg / cm ^{2 in} the state where each cord is loaded with a tensile load of 5 kg (a tire in which a steel cord is embedded). Embedded in a normal rubber material used for breakers), vulcanized, and then taken out the steel cord, disassembling the cord and observing a fixed length between each wire, and observing the observed length. The ratio of the length with a trace of contact with the rubber material was calculated as a percentage, and the average value was displayed. This value must be 70 or more.

The salt water adhesive rubber coverage RC (%) was determined by making a rubber material-steel cord vulcanization test piece based on ASTM D2229, steel cord adhesion test, and then making the bottom of the test piece 10 in a 3% sodium chloride aqueous solution. After dipping for a day, a pulling test was carried out, and the rubber coverage of the cord surface after pulling was displayed. This value needs to be 60% or more.

Fatigue RF was conducted by embedding a plurality of steel cords in a rubber material having a 100% modulus of 35 Kg / cm ² to form a composite sheet, and using this sheet, a 3-point pulley bending fatigue test was conducted. The number of repetitions until fracturing of the cord through fretting wear, buckling, etc., was determined by a machine, and the cord of Conventional Example 1 was set as 100 and expressed as an index. The higher the value, the better the fatigue.

The manufacturing cost CO is a cost for obtaining each code and is related to the degree of manufacturing difficulty, the manufacturing time, etc., and is represented by an index with the code of Conventional Example 1 being 100. The lower the number, the better the manufacturing cost.

In Table 1, experimental NO. No. 1 is a steel cord with a 3 + 9 structure and the twist is very stable, but the penetration rate of the rubber material and the coverage rate of the salt water adhesive rubber are inferior.

Experiment No. 1 which is a conventional example. No. 2 is a steel cord having a 1 × 12 structure in which strands having the same wire diameter are twisted together, and although the manufacturing cost is excellent, the penetration rate of the rubber material and the coverage rate of the salt water-bonded rubber are inferior.

Experiment No. 1 which is a conventional example. No. 3 is a steel cord having a 1 × 12 structure in which strands of different wire diameters are twisted together, and is excellent in fatigue resistance and manufacturing cost, but is inferior in rubber material infiltration property and salt water adhesive rubber coverage.

Experimental NO. Nos. 4 to 7, 10 and 14 are steel cords having a 1 × 12 structure using a wire having a spiral small habit. _No. 4 has a wire diameter ratio (d ₁ / d ₂ ) different from that of the present invention, and the experiment _No. 5 to 7, 10 and 14 are different in shape from the present invention, so that all evaluation items cannot be satisfied.

On the other hand, the experimental NO. The steel cords of 8, 9, 11-13, and 15-17 satisfy all of the infiltration rate of rubber material, the coverage ratio of salt water-adhesive rubber, fatigue resistance and manufacturing cost, and are optimal as reinforcing materials for rubber products. There was found.

[0039]

[Effect]

 Since the steel cord for reinforcing rubber products of the present invention has the above-mentioned structure, a rubber infiltration path is formed from the outer periphery of the cord to the inside of the cord, and the rubber material is surely distributed between the individual wires, so that it is completely As a result, it is possible to prevent the corrosion of the cord, prevent the separation phenomenon between the rubber material and the cord, and extend the fatigue life of the rubber product. Further, buckling does not easily occur even when repeated bending stress is applied, and the amount of wear due to the fretting phenomenon is small, so that it is excellent in fatigue properties, and also has the excellent effect of reducing manufacturing costs.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a steel cord of Example 1.

FIG. 2 is a cross-sectional view showing a steel cord of Example 2.

FIG. 3 is a sectional view showing a steel cord according to a third embodiment.

FIG. 4A is a sectional view showing a conventional steel cord having a 1 × 12 structure. (B) is a sectional view showing a conventional steel cord having a 3 + 9 structure.

FIG. 5 is a cross-sectional view showing a conventional steel cord having a 1 × 12 structure using strands having different wire diameters.

[Explanation of symbols]

 1,5,7,13 ... Steel cord 2 ... Wires with a small spiral habit 3,4,6,8,10,11,12 ... Wires 9 ... Strands

Claims (1)

[Scope of utility model registration request] _1. A wire having a same diameter (d ₂ ) is arranged around a wire having a same diameter (d ₁ ), and the 12 wires are arranged in the same direction. In a steel cord for reinforcing rubber products having a 1 × 12 structure formed by twisting at the same pitch, the wire diameter ratio of the above-mentioned three wires and nine wires is d ₁ /
d ₂ = 1.02 to 1.25, and at least one of the three strands has a peculiar pitch P ₁ = 4d _{1 to} 35d.
_{1. A} steel cord for reinforcing a rubber product, which has a small spiral habit with an apparent outer diameter d ₀ = 1.08 d _{1 to} 1.5 d ₁ .