KR20070069017A - Steel cord for rubber product reinforcement - Google Patents

Abstract

2의 최대치가 코드 꼬임각의 1.2∼2.0배로 되도록 한다.In order to easily and surely obtain a steel cord for reinforcing a rubber product having a single layer twist having sufficient rubber penetration and excellent fatigue resistance, the cord is twisted with a single layer twist of 1 × n (n = 3 to 6). The steel cord 10 is composed of a normal filament 12 having no property other than the spiral property for the purpose and a spiral filament ll having the property of a small spiral shape different from the spiral property for twisting the cord. The angle between the tangent t2 on the projection plane of the trajectory projected on the horizontal plane after unwinding the filament by twisting, and the baseline r2 of the spiral nature for twisting the cord

The maximum value of 2 should be 1.2 to 2.0 times the cord twist angle.

Description

Steel cord for reinforcing rubber products {STEEL CORD FOR REINFORCEMENT OF RUBBER PRODUCTS}

1 is a cross-sectional view (a) of a steel cord of an example of an embodiment of the present invention and a cross-sectional view (b) of a steel cord of another example.

Fig. 2 is a side view of the steel cord shown in Fig. 1A.

FIG. 3 is a horizontal plane of the steel cord shown in FIG. 1 (a) after being untwisted and twisted to remove the strands having no properties other than the spiral properties for twisting the cord. Fig. (A) showing the trajectory projected on and a diagram showing the trajectory projected on the horizontal plane by unwinding the strands (helical filaments) having small spiral bends and then placing them horizontally, unlike the spiral properties for twisting the cord ( b).

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to steel cords used for reinforcement of rubber products such as tires for automobiles and conveyor belts, and more particularly, to steel cords having sufficient rubber penetration and excellent fatigue resistance.

Steel cord used for reinforcement of rubber products such as tires for automobiles and conveyor belts. For example, closed twisting of three to six wires (steel filaments) tightly twisted together The structure (so-called close type) is conventionally used well. The steel cords are arranged in parallel, coated in a rubber sheet, formed into a composite sheet, and then embedded in a rubber product. The three steel filaments are twisted together to form a 1 × 3 structure. In addition, according to the number of element wires, it is called 1x4, 1x5, 1x6 structure.

By the way, such a closed type steel cord has a longitudinally continuous void inside the cord, and when the composite sheet is formed by covering the steel cord with a rubber material, the void inside the cord does not penetrate the rubber material. It remains as a void. Therefore, this void decreases when rubber vulcanization and pressurization in the tire forming process is caused by the invasion of the rubber that surrounds the cord surface into the cord, but is not completely buried in rubber, so that the cord center extends in the longitudinal direction. It becomes a straw hollow part and is left. And the hollow part penetrates the moisture which results from the condensation of the gas produced by the rubber material, the moisture which invades from an external wound, etc. As a result, corrosion advances from the inside of a cord, While the strength of the steel cord decreases, the adhesion between the steel cord and the rubber material decreases, causing a so-called separation phenomenon in which the steel cord and the rubber material peel off. It becomes a factor to shorten.

In addition, steel cords having an open twist structure (so-called open type) with a loose twist combined with a single layer while providing a gap between each wire to sufficiently infiltrate the rubber material inside the cord are also considered. have. However, steel cords with an open twist structure need to have a large gap (at least 0.01 mm) between each wire in order to sufficiently infiltrate the rubber material into the cord, and when the gap is large, there is a free space in which each wire can move. As the wire becomes large, skew of element wires, etc. occur, the twist becomes uneven in the longitudinal direction, and buckling easily occurs when repeated bending stress is applied, and also under extremely low loads. Since the elongation is large, not only the handling workability is poor, but also the gap between the gaps decreases due to the tension applied at the time of forming the composite sheet, and the rubber material may not sufficiently enter the cord.

Therefore, unlike spiral properties for twisting cords, twisted wires having a small spiral shape or wave shape and straight wires having no properties other than spirals for twisting cords are combined. Steel cords having a single twist have been developed (see, for example, Japanese Patent Application Laid-Open No. 7-68673 and Japanese Patent No. 33179915).

As described above, the steel cord of single-twist twist combines strands having a small spiral shape or wave shape unlike straight spirals as described above, and straight wires having no properties other than spiral properties for twisting cords. By making it a structure, even if twisting itself becomes dense, the space | interval which makes a rubber material penetrate between wires in a twisted state by the small spiral shape of a some wire, or a wave form property, and also forms a composite sheet with a rubber material With respect to the tension applied at the time, the extension of the steel cord can be suppressed by the drag force of the straight wire, and the small spiral shape or the waveform property can be prevented from disappearing, and the rubber material is sufficiently contained inside the cord. It becomes possible to keep between wires as much as invading, and twist itself It is possible to make the steel cord excellent in fatigue resistance which prevents elongation under extremely low load, improves handling workability, stabilizes twisting in the cord length direction, and prevents buckling even by repeated bending stress. I think it is done.

However, it is difficult to say that steel cords having a single layer twist combined with an elemental wire having a small spiral shape or corrugated property and an elemental wire having a straight structure combine both sufficient rubber penetration and excellent fatigue resistance. In order to achieve sufficient rubber penetration resistance and excellent fatigue resistance, each time the number of wires and the wire radius of the cord are different, the setting of the number of property grants, the pitch of property grants, the height of the property grants, and the like, are performed on both sides of the rubber penetration and fatigue resistance. It is necessary to specify the optimum setting by evaluating from the above, and the specification is not easy.

Accordingly, an object of the present invention is to easily and reliably obtain a steel cord for reinforcing single layer twisted rubber products having sufficient rubber penetration and excellent fatigue resistance.

Steel cord for reinforcing rubber products of the present invention is a single-layer twist formed by twisting n wires (n = 3 to 6) together, and at least one wire is a small spiral shape or waveform property unlike spiral properties for cord twisting. Wherein at least one of the wires having a spiral shape or wave shape has at least one wire twisted and untwisted in the projected plane when the wires are laid out horizontally and projected onto a horizontal plane. It is characterized in that the maximum value of the angle with the spiral baseline for 1.2 to 2.0 times the cord twist angle.

The property of a small spiral shape is a property of three-dimensional spiral shape, and the property of a waveform is a two-dimensional property of the shape which projected the spiral, and both are smaller than the spiral property for cord twisting, and have an equivalent effect. In addition, the direction of a spiral-like property may be the same as a cord twist direction, and may be a reverse direction.

This steel cord has a small spiral shape or waveform property unlike at least one element wire of n wires (n = 3 to 6), which is a twisted wire. Air gap is formed, and at least one of the wires having a small spiral shape or corrugation property is the tangent of the wire on the projection surface when the wire is laid horizontally and projected on the horizontal plane after the twist of the steel cord And the maximum value of the angle between the spiral baseline for cord twist is 1.2 to 2.0 times the cord twist angle, thereby reducing the drag on load when tension is applied, for example, in forming a composite sheet with a rubber material. By making it small, it prevents the extension of the steel cord and prevents the disappearance of the small spiral shape or wave shape. It is possible to maintain the void as much as it penetrates between the wires, to stabilize the shape of the twist in the cord length direction, and to have excellent fatigue resistance in which buckling does not easily occur even by repeated bending stress.

For wires with small spiral shape or corrugation properties different from the spiral properties for cord twisting, the wire tangents and cord twists on the projected surface when the wires after twisting the steel cord are laid horizontally and projected on the horizontal plane If the maximum value of the angle with the spiral baseline is less than 1.2 times the cord twist angle, the voids (at least 0.01 mm or more) as long as the rubber material penetrates the cord center cannot be obtained. In addition, the maximum value of the angle between the tangent of the element wire on the projection plane and the spiral reference line for the cord twist when the element wire after twisting the steel cord is laid horizontally and projected on the horizontal plane is larger than 2.0 times the cord twist angle. The larger the drag against the load of the element, the greater the elongation of the entire cord when the steel cord is loaded with tension, the voids can not be secured enough to invade the rubber material inside the cord, The shape becomes nonuniform, and fatigue resistance falls.

As described above, according to the present invention, a steel cord for reinforcing a single-layer twisted rubber product having sufficient rubber penetration and excellent fatigue resistance can be easily and surely obtained.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

The steel cord of the present embodiment is a steel cord 10 having a 1 × 3 structure formed by twisting three wires (filaments), for example, as shown in Fig. 1 (a). Straight wires having a small spiral shape different from spiral properties for cord twisting (spiral filaments), and the other two wires 12 are straight wires having no properties other than spiral properties for cord twisting. It is formed as (normal filament) by twisting them together. Here, the property of a small spiral shape is a three-dimensional spiral property. The direction of the spiral-like property may be the same as the cord twist direction or may be in the reverse direction.

The steel cord is also a steel cord having a 1 × 3 structure formed by twisting three wires (deep filaments), for example, as shown in FIG. ) Is an element wire having a wave form property different from the spiral property for cord twisting, and the other two element wires 22 are straight wires (normal filaments) having no properties other than spiral properties for cord twisting. ), And the steel cord 20 formed by twisting them together may be sufficient. Here, the waveform property is a two-dimensional property of the shape in which the spiral is projected.

The element wires 11 and 21 having a spiral shape or wave shape have the same element wire diameter as other element wires 12 and 22 that are straight, and as shown in FIG. 2, the property pitch P ₁ is smaller than the twist pitch P, When P ₁ = 0.1P to 0.7P and the apparent outer diameter d ₁ is the element wire diameter d, d ₁ It is imparted in a spiral shape or waveform so that it is (d + 2 / 100mm) to (d + 2 / 10mm). Here, the property pitch P ₁ is the spiral (spiral) pitch (see FIG. 2) or the waveform pitch of the element wires imparted, and the apparent outer diameter d ₁ is the longitudinal direction of the element wires 11 imparted in a spiral shape. The circumference of the circumscribed circle A1 (see Fig. 1 (a)), or the wave height of the element wire 21 imparted by the waveform (external projection ellipse A2 viewed from the length direction (b of Fig. 1) Corresponds to the long diameter)).

1은 어떠한 경우에 있어서도 코드 꼬임각과 같은 각도, 혹은 그 이하의 각도이지만, 코드 꼬임을 위한 스파이럴 성질과는 다른 작은 스파이럴 형상의 성질을 갖는 소선(11)(스파이럴 필라멘트)에 대하여는, 꼬임을 푼 후 수평으로 배치하여 수평면에 투영한 궤적은, 예컨대 도 3의 (b)에 도시하는 바와 같이, 투영면에서의 접선 t2와 코드 꼬임을 위한 스파이럴 성질의 기준선 r2와의 이루는 각도

2는 국지적(局地的)이지만 코드 꼬임각보다 크고, 그 각도

2의 최대치가 코드 꼬임각의 1.2∼2.0배로 되도록 성질 부여된다.In addition, in the case of the steel cord 10 which is the element wire 11 having a small spiral shape property different from the spiral property for the cord twist, the element wire having no property other than the spiral property for the cord twist ( 12) (typical filament) is a horizontally arranged trace after untwisting, and the trajectory projected on the horizontal plane is, for example, as shown in FIG. Angle with reference line r1

1 is an angle equal to or less than the cord twist angle in any case, but for the element wire 11 (spiral filament) having a small spiral shape property different from the spiral property for cord twist, after twisting, The trajectory arranged horizontally and projected onto the horizontal plane is, for example, the angle formed by the tangent t2 on the projection plane and the reference line r2 of spiral nature for twisting the cord, as shown in FIG.

2 is local but larger than the cord twist angle

It is tempered so that the maximum value of 2 may be 1.2 to 2.0 times the cord twist angle.

2가 국지적이지만 코드 꼬임각보다 크고, 그 각도

2의 최대치가 코드 꼬임각의 1.2∼2.0배로 되도록 성질 부여된다.Also, in the case of the steel cord 20, which is the element wire 21 having one small wire having a small waveform property different from the spiral property for cord twisting, similarly, a small waveform property different from the spiral property for cord twisting is obtained. With respect to the element wire 21 having a twist, the trajectory after the twist is placed horizontally and projected on the horizontal plane is an angle between the tangent t2 on the projection plane and the spiral reference line r2 for the cord twist.

2 is local but greater than the cord twist angle, and that angle

It is tempered so that the maximum value of 2 may be 1.2 to 2.0 times the cord twist angle.

2의 최대치가 코드 꼬임각의 1.2∼2.0배로 되도록 성질 부여된 것인 것에 의해, 고무재와의 복합체 시트 성형에 있어서 장력이 부하되었을 때의 부하에 대한 항력의 저하는 작고, 스틸코드(10, 20)의 신장이 억제될 수 있어, 코드 내부에 고무재가 충분히 침입하는 만큼의 공극이 유지됨과 아울러, 꼬임의 형상이 안정하고, 반복 굽힘응력에 의해도 좌굴이 쉽게 생기지 않는 내피로성이 우수한 것으로 된다.These steel cords 10 and 20 are, for example, coated with unvulcanized rubber around them and molded into a composite sheet with a rubber material, and embedded in the rubber of the tire body during tire molding as a tire reinforcing material. . In that case, when unvulcanized rubber is coated around the steel cords 10 and 20, the unvulcanized rubber is voided between the elemental wires 11 and 21 and the elemental wires 12 and 22 provided with the properties. It penetrates into the cord from (C1, C2), vulcanizes at the time of tire formation, and penetrates into the hollow part B1, B2 of a cord center. At this time, the steel cords 10 and 20 are formed by the traces 11 and 21 having a small spiral shape or waveform characteristics different from the spiral properties for twisting the cord, and are laid out horizontally after being twisted. , The angle between the tangent t2 on the projection plane and the baseline r2 of the spiral nature for cord twist

Since the maximum value of 2 is imparted so as to be 1.2 to 2.0 times the cord twist angle, the drop in drag against the load when the tension is loaded in forming a composite sheet with a rubber material is small, and the steel cord 10, 20) elongation can be suppressed, the voids are maintained as long as the rubber material sufficiently infiltrates into the cord, the shape of the twist is stable, and the fatigue resistance is excellent because the buckling is not easily caused by repeated bending stress. .

2의 최대치가 코드 꼬임각의 1.2배보다 작으면, 고무재가 코드 중앙부분으로 침입하는 만큼의 공극(적어도 0.01mm 이상)을 얻을 수 없다. 또한, 스틸코드(10, 20)를 꼬임을 푼 후의 소선(11, 21)을 수평으로 배치하여 수평면에 투영하였을 때의 투영면에서의 소선(11, 21)의 접선 t2와 코드 꼬임을 위한 스파이럴 성질의 기준선 r2와의 이루는 각도

2의 최대치가 코드 꼬임각의 2.0배보다 크면, 그 소선(11, 21)의 부하에 대한 항력이 작아져, 스틸코드(10, 20)에 장력이 부하되었을 때의 코드 전체의 신장이 커지고, 코드 내부에 고무재가 충분히 침입하는 만큼의 공극을 확보할 수 없게 됨과 아울러, 꼬임의 형상이 불균일하게 되어, 내피로성이 저하한다.The wires 11 and 21 of the wires 11 and 21 having a small spiral shape or wave shape different from the spiral properties for twisting the wires are arranged horizontally after the wires 11 and 21 are unwound. Angle formed between the tangent t2 of the element wires 11 and 21 on the projection plane when projected onto the horizontal plane and the baseline r2 of the spiral property for cord twisting

If the maximum value of 2 is smaller than 1.2 times the cord twist angle, voids (at least 0.01 mm or more) as long as the rubber material penetrates into the cord center portion cannot be obtained. Further, the spiral properties for twisting the wires t2 of the wires 11 and 21 on the projection plane when the wires 11 and 21 are horizontally arranged and projected onto the horizontal plane after the steel cords 10 and 20 are untwisted. Angle with reference line r2 of

When the maximum value of 2 is larger than 2.0 times the cord twist angle, the drag force on the loads of the element wires 11 and 21 is reduced, and the elongation of the entire cord when the steel cords 10 and 20 are loaded with tension is increased. The gap as long as the rubber material sufficiently infiltrates into the cord cannot be secured, the shape of the kink becomes nonuniform, and the fatigue resistance decreases.

2의 각도

2의 최대치가 코드 꼬임각의 1.2∼2.0배로 되도록 하고 있지만, 작은 스파이럴 형상 또는 파형의 성질을 갖는 소선(11, 21)은 스틸코드(10, 20)를 구성하는 소선 중, 적어도 1개이면 좋고, 복수개이라도 좋다(전부라도 좋다). 또한, 스파이럴 형상 또는 파형의 성질을 갖는 소선(11, 21)이 복수개인 경우, 꼬임을 푼 후 수평으로 배치하여 수평면에 투영한 궤 적이 투영면에서의 접선 t2와 코드 꼬임을 위한 스파이럴 성질의 기준선 r2와의 이루는 각도

2의 각도

2의 최대치가 코드 꼬임각의 1.2∼2.O배로 되도록 하는 소선은 적어도 1개이면 좋고, 복수개이라도 좋다(전부라도 좋다).On the other hand, in the illustrated example, of the three element wires constituting the steel cords 10 and 20, each of the two element wires 12 and 22 is an element element having straightness, and each element wire 11 and 21 is used. ) Is a small spiral shape or corrugated wire, and each single wire 11 or 21 having the small spiral shape or corrugated property is twisted and placed horizontally to project the trajectory projected on the horizontal plane. Angle between the tangent t2 at and the baseline r2 of the spiral nature for cord twist

2, angle

Although the maximum value of 2 is set to 1.2 to 2.0 times the cord twist angle, the element wires 11 and 21 having a small spiral shape or wave shape may be at least one of the element wires constituting the steel cords 10 and 20. Plural number may be sufficient (all may be sufficient). In addition, when there are a plurality of element wires 11 and 21 having a spiral shape or wave shape, the traces projected on the horizontal plane after untwisting and twisting are twisted. Angle with

2, angle

At least one element wire may be sufficient so that the maximum value of 2 may be 1.2 to 2.0 times the cord twist angle, or a plurality of wires may be used (all may be used).

In addition, although the example shown is a case of 1x3 structure, this invention is similarly applicable to the steel cord of 1x4, 1x5, and 1x6 structure.

Table 1 shows the test results of prototypes of steel cords of various configurations in which a plurality of strands of brass plating on the surface were twisted together. One embodiment of the cord of the present invention has a 1 × 3 structure, an element diameter of 0.30 mm, a number of element elements having a small waveform property, a cord pitch (twist pitch) of 16 mm, a twist angle (cord twist angle) of 3.875 degrees, the maximum angle of waveform application (7.1 maximum, the angle between the tangent on the projection plane of the trajectory projected on the horizontal plane after untwisting and projected on the horizontal plane and the spiral baseline for twisting the cord) Is a steel cord having a ratio of 1.832 to a twist angle, and another code of the present invention (Example) includes a 1 × 4 structure, an element diameter of 0.30 mm, and a number of element elements having a small waveform property. The steel cord has a cord pitch of 16 mm, a twist angle of 4.761 degrees, a maximum waveform attach angle of 6.25 degrees, and a ratio of the maximum waveform attach angle to the twist angle of 1.313. One of the comparative examples is a 1 × 3 structure, an element diameter of 0.30 mm, a number of element wires having a small waveform property, a cord pitch of 16 mm, a twist angle of 3.875 degrees, a waveform giving maximum angle of 4.5 degrees, and a waveform giving. The steel cord has a ratio of 1.161 to the maximum angle and the twist angle. Another comparative example is a 1 × 3 structure, an element diameter of 0.30 mm, the number of element wires having a small wave-like property, a cord pitch of 16 mm, and an angle of twist of 3.875. It is a steel cord with a maximum wave angle of 7.9 degrees and a ratio of maximum wave angle of twist to angle of twist of 2.039. Further, the conventional example is a steel cord having a 1 × 3 structure and a closed type of 0.30 mm of wire diameter, having a cord pitch of 16 mm and a twist angle of 3.875 degrees.

In this test, the steel cords are buried and vulcanized in a state where 49 N tensile load is applied to each steel cord, the steel cords are removed from the rubber, the wires are removed, the entire wire wire is observed, and the area ratio in contact with the rubber material is measured. It investigated and expressed as "rubber permeability (%)."

In addition, a tensile load of 49 N was applied to each steel cord, and the elongation was measured and expressed as "low load elongation".

Further, steel cords of the same specification are embedded in a plurality of rubber sheets, and the three-point pulley bend fatigue is repeated for a predetermined number of times, and the cords are removed from the rubber sheets after that. ) Was measured and compared with the breaking strength before the fatigue test, and the results were expressed as "fatigue resistance". The smaller the index, the lower the fatigue resistance.

In addition, the complexity of the work during the production of the steel cord and the handling of the cord at the time of forming the composite sheet were expressed as "workability". The larger the index, the higher the workability.

The cord (Example) of the present invention has excellent rubber penetration and fatigue resistance, relatively low elongation during deterioration, and less deterioration of workability. In contrast, the steel cord of the comparative example was out of the range of 1.2 to 2.0 of the maximum corrugation angle and the twist angle, and the ratio of 1.161 (less than 1.2) had poor rubber penetration, and this ratio was 2.039 (more than 2.0). Large) has a high elongation during degradation, and is poor in fatigue resistance and workability.

As described above, according to the present invention, a steel cord for reinforcing a single-layer twisted rubber product having sufficient rubber penetration and excellent fatigue resistance can be easily and surely obtained.

Claims (1)

A single-layer twist consisting of twisting n wires (n = 3 to 6), wherein at least one wire is a steel cord having a small spiral shape or waveform property unlike spiral properties for cord twisting. At least one of the wires having a spiral shape or corrugation property has a spiral property for twisting the wires of the wires in the projected surface when the wires after twisting the steel cords are horizontally arranged and projected on a horizontal plane. Steel cord for reinforcement of rubber products, characterized in that the maximum value of the angle formed from the reference line is 1.2 to 2.0 times the cord twist angle.

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