JPH076297U - Steel cord for reinforcing rubber products - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to improve the penetration of rubber and to obtain a steel cord that is a complete composite with rubber, preventing the separation phenomenon, fretting phenomenon, and deterioration of mechanical strength, Extend the life of rubber products. [Structure] A steel cord comprising a core formed by arranging two to six strands substantially in parallel without twisting each other and a sheath formed by twisting five to nine strands around the core. The wire diameter is 0.10 to 0.40 mm, and at least one wire of the core is of the formula: P ₁ = 6d to 30d d ₁ = (d + 2 / 100mm) to (d + 2 / 10mm) (however, P ₁ : Pitch pitch (mm), d: Element wire diameter (m
m), d ₁ : a substantially spiral habit that satisfies the apparent outer diameter (mm), and a gap C of 0.04 to 0.15 mm between at least one adjacent strand forming the sheath. It will be provided.

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]

 Generally, many steel cords of this type are covered with a rubber material in a state where they are aligned in parallel and are used as a reinforcing material for rubber products such as automobile tires and conveyor belts.

As a conventional steel cord for reinforcing a rubber product, as shown in FIG. 3, a core 22 formed by closely twisting three substantially straight strands 21 and nine substantially straight wires around the core 22. There is known a steel cord 25 having a sheath 24 formed by closely twisting the individual wires 23.

However, since the steel cord 25 has the above-described configuration, the wires 21, 21 forming the core 22 are always in contact with each other, and the wires 21, 23 between the core and the sheath are also in contact. They are placed in close or very close proximity. Therefore, in the steel cord 25, when the rubber product is molded, the rubber material cannot infiltrate into the cavity D from between the above-mentioned strands, and only covers the outer periphery of the steel cord 25. Complex could not be formed.

Therefore, in the tire using the steel cord 25, since the wire and the rubber material are not sufficiently adhered to each other, a so-called separate phenomenon occurs in which the wire and the rubber material are separated when the automobile is running. In addition, some of the strands are broken due to the fretting phenomenon caused by the contact between adjacent strands, and the slight gaps between the strands cause the moisture in the rubber and the moisture infiltrated by the cuts in the tire. It became a propagation path of the steel cord, and rust was generated on the entire steel cord, which was also a cause of drastically reducing the mechanical strength of the steel cord.

In recent years, in order to eliminate the above problems, a steel cord has been developed in which the number of strands forming a sheath that allows rubber material to sufficiently penetrate into the cord is reduced and a gap is provided between adjacent strands. Has been done.

[0007]

[Problems to be solved by the device]

 However, even in the core of the above steel cord, the strands are in close contact with each other, and the rubber material cannot penetrate into the cavity D, so the adverse effects of the above-mentioned separation phenomenon, fretting phenomenon or deterioration of mechanical strength are sufficiently caused. It cannot be resolved.

The present invention has been made in order to eliminate the above-mentioned problems, and a rubber material infiltration route is provided from the outer circumference of the cord to the center of the cord, so that the rubber material can be introduced between the strands of the steel cord. It is an object of the present invention to provide a steel cord for reinforcing a rubber product, which has a significantly improved infiltration property and can be formed into a complete composite with rubber.

[0009]

[Means for Solving the Problems]

The steel cord for reinforcing a rubber product of the present invention has been made to solve the above-mentioned problems, and includes a core formed by arranging two to six strands of wires in a substantially parallel manner without twisting each other, and the periphery of the core. In a steel cord composed of a sheath formed by twisting 5 to 9 strands, the diameter of each strand is 0.10 to 0.40 mm, and at least one strand has a core, _{P 1 = 6d~30d d 1 = (} d + 2 / 100mm) ~ (d + 2 / 10mm) ( provided that, P _1: habit pitch (mm), d: wire diameter (mm), d _1: the outside diameter of the apparent (mm )) Is satisfied, and a gap C of 0.04 to 0.15 mm is provided between at least one adjacent strand forming the sheath.

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 of each element wire is set to 0.10 to 0.40 mm because the strength of the steel cord is insufficient if it is less than 0.10 mm and the flexibility is poor if it exceeds 0.40 mm. .

In addition, in the substantially spiral habit, when the wire diameter is d, the habit pitch P ₁ Is P₁ = 6d to 30d, and apparent outer diameter d₁ = (D + 2/100 mm) to (d + 2/10 mm) is set for the following reason. Habit pitch P₁ If is less than 6 d, unreasonable plastic deformation is applied to the strands during the staking, the strands are easily broken, and the productivity is reduced. On the other hand, if it is larger than 30d, the gap between the strands will be 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 cord surface, and the infiltration of the rubber material will not be sufficient. Is. Furthermore, the apparent outer diameter d₁ Is less than d + 2/100 mm, even if a rubber material with good fluidity is used, the rubber material cannot fully penetrate into the steel cord during pressure vulcanization. This is because the stability of is deteriorated and the fatigue resistance is reduced.

Further, the gap C of 0.04 to 0.15 mm is provided between at least one adjacent element wire forming the sheath, because when it is smaller than 0.04 mm, sufficient rubber material can penetrate into the inside of the steel cord. This is because the shape stability of the wire deteriorates if the diameter is larger than 0.15 mm.

It should be noted that the substantially spiral-shaped habit referred to in the present invention does not need to be exactly spiral-shaped, and may be simply wavy, and exhibits the same effect as the spiral-shaped. Is.

[0015]

[Action]

 When the steel cord configured as described above is sandwiched between two rubber sheets and subjected to pressure vulcanization, the rubber is formed by the minute gaps formed between adjacent strands of each layer of the steel cord and the same layer. Material sufficiently penetrates inside the cord. This rubber material coats the circumference of each wire, forming a complete composite of rubber and cord, and prevents the separation phenomenon, fretting phenomenon and deterioration of mechanical strength.

[0016]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 6 is a steel cord formed by twisting nine strands 4 having a diameter of 0.20 mm around a core 3 made of three strands having a diameter of 0.22 mm and arranged in parallel. Is. The core 3 has one strand 2 having a substantially spiral habit having a habit pitch P ₁ of 6.0 mm and an apparent outer diameter d ₁ of 0.38 mm and a substantially straight strand 1. The two wires are aligned in parallel, and around the core 3, nine straight wires 4 are twisted in the S twist direction with a twist pitch of 12.5 mm to form a sheath 5.

[0017]

Example 2 As shown in FIG. 2, it has a substantially spiral habit with a wire diameter d of 0.22 mm, a habit pitch P ₁ of 6.0 mm, and an apparent outer diameter d ₁ of 0.38 mm. The strands of wire 8 and two strands 7 of substantially straight wire diameter 0.22 mm are aligned in parallel, and eight strands of substantially straight strands 10 of wire diameter 0.22 mm are twisted around them to form a pitch of 12.5 mm. Then, the sheath 11 was formed by twisting in the S twist direction to form the steel cord 12 for reinforcing the rubber product.

The steel cords 6 and 12 having the substantially spiral habit in each of the above-described examples were produced using a tubular type twisting machine.

In each of the above-described embodiments, the number of strands forming the core is three and the number of strands forming the sheath is 9 or 8, but the number of strands forming the core is 2 to 6, and the sheath is formed. It is possible to use 5 to 9 strands.

The twist pitch of the sheath is preferably in the range of 10.0 to 16.0 mm. The reason is that when the twist pitch is less than 10.0 mm, the strength of the steel cord becomes too low, and when it exceeds 16.0 mm, the fatigue resistance is lowered.

[0021] A steel wire having a carbon content of 0.70 to 0.90 wt% is usually used for the wire constituting the steel cord. However, in order to give the steel cord high strength and good toughness, the carbon content is It is more preferable to use a steel wire of 0.80 to 0.85 wt%.

In order to improve the adhesion between the rubber material and the steel cord, it is preferable to use each of the above-mentioned strands which has been plated with brass plating, bronze plating or the like.

Next, the steel cord of the present invention was evaluated for rubber penetration rate, fatigue value, twisting process number, and cost together with the conventional example, and the results shown in Table 1 were obtained. In addition, all the wires constituting each cord used for the test have a carbon content of 0.82 wt%, and the surface thereof is brass-plated.

In the evaluation, the rubber infiltration rate was determined by embedding each cord in a rubber material with a tensile load of 5 kg, vulcanizing under pressure, pulling out the cord, and disassembling the cord. A certain length of each strand was observed, and the ratio of the area with the trace of contact with the rubber material to the observed area was calculated as a percentage, and the average value was displayed.

Fatigue value means that a plurality of steel cords are embedded in a rubber material having a 100% modulus of 35 kg / cm ² to form a composite sheet, and this sheet is used to perform 3-point bending bending fatigue. The number of repetitions until fracturing of the cord through fretting wear, buckling, etc. was determined by a testing machine, and the cord of Conventional Example 1 was set to 100 and displayed as an index.

[0026]

[Table 1]

As is clear from Table 1, the steel cord of the present invention can satisfy both the rubber penetration rate and the fatigue value. For example, when the steel cord of the present invention is used for a tire, It can be expected to further improve the service life and riding comfort of the car. In addition, since the steel cord of the present invention can be twisted in one step, the cost can be significantly reduced (twisting cost is 30 to 30%) compared with the conventional steel cord.

[0028]

[Effect of device]

 Since the steel cord for reinforcing rubber products of the present invention has the above-mentioned structure, a rubber penetration path is formed from the outer circumference of the cord to the inside of the cord, and the rubber material surely penetrates into the inside of the cord, and the cord and the rubber material are completely It becomes a complex. Therefore, when the steel cord of the present invention is used for, for example, a tire, the separation phenomenon, the fretting phenomenon and the deterioration of mechanical strength can be significantly reduced.

In addition, since the strength as a steel cord is sufficient and the twist is stable, it has an excellent practical effect that the life of the tire can be greatly extended.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a steel cord of the present invention.

FIG. 2 is a schematic sectional view showing another embodiment of the steel cord of the present invention.

FIG. 3 is a schematic sectional view of a conventional steel cord.

[Explanation of symbols]

 1, 4, 7, 10, 21, 23 Strands 2, 8 Strands having a substantially spiral habit 3, 9, 22 Cores 5, 11, 24 Sheaths 6, 12, 25 Steel cord

Claims (1)

[Scope of utility model registration request] 1. A steel cord comprising a core formed by arranging 2 to 6 strands substantially in parallel without twisting each other and a sheath formed by twisting 5 to 9 strands around the core, Each of the strands has a diameter of 0.10 to 0.40 mm, and at least one strand of the core has the formula: P ₁ = 6d to 30d d ₁ = (d + 2/100 mm) to (d + 2/10 mm) (however, P ₁ : habit pitch (mm), d: wire diameter (m
m), d ₁ : has a substantially spiral habit that satisfies the apparent outer diameter (mm), and further, a gap C of 0.04 to 0.15 mm is provided between at least one adjacent wire forming the sheath. A steel cord for reinforcing rubber products, which is characterized by being provided.