KR20100134328A - A steel cord and method for manufacturing of it - Google Patents

Abstract

PURPOSE: A steel cord and method for manufacturing the same are provided to obtain plural single line steel cords by giving twisting force and wave to steel cords. CONSTITUTION: Steel cords of two strands are provided through a supply unit(21). Through the combination of first twisting unit(22) and a second twisting unit(24), the steel cords are twisted. Under the application of minute twisting, a waveform giving unit(23) gives a gear waveform to the steel cords. The steel cords are collected in a winding unit(29) through a withdrawal unit(28) through a correction roller(25) and a guide roller(27).

Description

Technical Field [0001] The present invention relates to a single-steel cord for rubber reinforcement excellent in linearity and a manufacturing method thereof,

The present invention relates to a single-wire steel cord and a method of manufacturing the same. More particularly, the present invention relates to a single-wire steel cord and a method of manufacturing the same, which can improve the linearity and lighten the weight of the tire, And more particularly, to a single-steel cord for rubber reinforcement excellent in linearity and a method of manufacturing the same.

Among various types of reinforcing materials used for reinforcing elastomeric products such as vehicle tires and conveyor belts, steel cords have a higher strength, modulus, heat resistance, heat transfer rate, fatigue resistance and adhesion than other kinds of reinforcing materials. And therefore, the amount of use thereof has been rapidly increasing, which has been widely used for reinforcement of tires in particular.

On the other hand, a radial tire in which an inner space is filled with air is composed of a carcass portion in the form of a radiation, and a belt layer arranged on the outside in the carcass radial direction to reinforce the tread portion.

In the belt layer and the carcass layer of such radial tires, a steel cord, which is formed by twisting about 2 to about 20 twin fine wire wires each having a circular cross section having a diameter of 0.15 to 0.38 mm, Layer and the carcass layer are reinforced.

The steel cord, which is embedded in the rubber product and functions as a stiffener, has a complicated structure due to a large number of strands constituting the steel cord, and it requires a stranding process for twisting the strands during manufacturing of the steel cord, The manufacturing cost is increased.

Further, since the adjacent steel wires are connected to each other in a state of being in contact with each other, fine voids are present inside the cord. Such voids are formed in the steel pipe through the passage for amplifying the corrosion of the steel wire when moisture permeates between the rubber Resulting in a sudden damage of the adhesive layer between the rubber and the steel cord, and there is a fatal problem that the belt layer and the steel cord are separated from each other.

In addition, under the conventional steel cord structure, a fretting occurs on the contact portion due to the contact between the strands when a harsh external pressure, which is repeatedly stretched and compressed due to repetitive bending motion accompanying the rotation of the tire, is transmitted to the steel cord And fatigue of the tire is weakened. As a result, the durability of the tire is deteriorated.

In recent years, in order to reduce the fuel consumption of vehicles, it is required to reduce the weight of the tires to protect the environment. Therefore, there is an interest in the development of a new steel cord which can reduce the weight of the steel cord itself.

In order to solve these problems, it has been proposed to use a single-wire steel cord for a belt layer of a tire in place of a steel cord in which a plurality of wire strands are stranded.

The use of only a single strand of steel wire instead of a twisted steel cord can reduce the total amount of steel used as a reinforcing material and ultimately reduce the weight of the tire have.

Also, since the rubber is completely covered around the single-wire steel cord, the durability against the endothelium due to the corrosion due to the moisture penetration and the decrease in the adhesion can be improved.

However, in the case of general disconnection, particularly in the case of a very fine water such as a steel cord for a tire reinforcing material (wire having a very small diameter), linearity tends to vary due to a mechanical factor such as a wire material, a drawing machine or a twisting machine. It is very difficult to have sex.

In general, the linearity of the steel cord is assessed by "Arc Height". If the arc height is excessively large or uneven, the calender of the tire manufacturing process (the steel cord on the thin rubber sheet side by side, And the steel cord is sandwiched between the rubber sheets). In the cutting process, the topping sheet is twisted or defective such as buckling easily occurs.

In addition, in the case of a conventional round wire, that is, a single-wire steel cord without a waveform, there is a disadvantage that so-called " core migration "occurs in which the wire breaks out of the tread due to repeated bending movements during tire running and causes fatal damage to the tire.

1 and 2 as prior patents relating to single wire steel cords and disclosed in patent registration No. 0567812. [ The steel cord 10 is a flat wire 2a in which a single filament 2 of circular filaments 2 is squeezed by a pair of rolling rollers 7 through a drawing machine 5 to form a flat wire 2a having at least one flat surface, And at least one twisted portion 12 is formed in the spiral-shaped portion. The twisted portion 12 is formed in a spiral shape in an open structure by a torsional stress generated by the winding twist 9. The pitch (p) between the center portions of the twist portions 12 is formed to be 5 to 40 mm so as to have an open helical structure.

The steel cord 10 having such a structure has an effect of improving the endurance and rotatability and linearity due to the flatness ratio and the winding torsional stress, and improving the permeability and adhesion when joining with the rubber member due to the open spiral shape .

However, in the single-wire steel cord 10 having such a structure, not only the weight of the steel cord accommodated in the tire is increased due to the plurality of twist portions 12 but also the tire itself is damaged due to deformation of the twist portion 12 during running There is a problem.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems and it is an object of the present invention to provide a steel cord for reinforcing rubber products having a twisted wire structure using a plurality of steel wires, And a single line rotating along the hypercycloid curve in a substantially periodic three-dimensional shape along the longitudinal direction, it is possible to improve the linearity without reducing the other quality characteristics required by the tire reinforcement, And it is an object of the present invention to provide a single-wire steel cord for tire reinforcement which is advantageous also in terms of tire uniformity ultimately as well as automatic joining and productivity of a tire cutting process.

Another object of the present invention is to provide a rubber reinforcing material which is advantageous for reducing the weight of a tire by using only one single-strand steel cord and which is economical compared to a conventional wire-like steel cord and a manufacturing process of a single wire steel cord.

It is still another object of the present invention to provide a method of manufacturing a single wire steel cord which can be easily manufactured by attaching a simple torsion and wave form imparting device to a drawing machine without requiring additional manufacturing facilities.

The single steel cord for rubber reinforcement according to the present invention for achieving the above object assumes X-Y-Z three-axis coordinates orthogonal to each other,

A single-wire steel cord made of a single strand wire, wherein a trajectory shape in which a two-dimensional waveform is formed in the XY plane in the longitudinal direction along the X axis and in which the two-dimensional waveform periodically rotates three- And is moved along the hypocycloidal curve.

If the three-dimensional circumferential length of the two-dimensional waveform is F (mm) and the small diameter of the single-strand steel cord is d (mm), the three-dimensional circumferential length F 1 of the two- &Lt; F l < 3000 d (F l: distance until the two-dimensional waveform rotates 360 [deg.])

Further, in the present invention, if the small diameter of the single wire steel cord is d (mm), the code diameter Fh of the three-dimensional trajectory shape is 0.1 + d <Fh <1.0 + d.

The steel cord of the present invention is characterized in that the range of the unit angle (angle between F ₀ and F ₁ ) where the two-dimensional waveform rotates along the three-dimensional hypocycloid curve is 0.5 ° to 30 °.

In the steel cord of the present invention, the pitch interval (P ₂ ) of the two-dimensional waveform is 2 d to 350 dmm.

The steel cord of the present invention is characterized in that the wave height (h) of the two-dimensional waveform is 0.02 d to 10 dmm.

The steel cord of the present invention is characterized in that the linearity (mm / 400 mm) ranges from 0 to 60 mm.

The steel cord of the present invention is characterized by having a small wire diameter of 0.08 to 1.0 mm, a carbon content of 0.7 to 1.50 weight%, and a tensile strength of 270 to 500 kgf / mm 2.

The steel cord of the present invention is characterized in that a brass plating layer is formed on the surface portion of the single wire steel cord to a thickness of 0.05 to 20 탆.

According to another aspect of the present invention, there is provided a method of manufacturing a steel cord, comprising the steps of feeding a plurality of strands of steel wire through respective supply portions, sequentially passing through a first twisting device and a second twisting device, The material itself is twisted but the twist is imparted so that the strands are not twisted together, a gear waveform is imparted through the corrugating device, a guide roller, which is an abutment end for individually dividing each of the steel wires, And winding it on a winding part.

In the method of manufacturing a steel cord according to the present invention, the rotation ratio of the first twisting device and the second twisting device (the second twisting device / the first twisting device) is 0.1 to 1.5 times.

The present invention is not a structure in which a plurality of strands are connected to each other as in a conventional wire-type steel cord but a plurality of single-strand steel cords can be obtained by applying a plurality of strands of wire, It is advantageous from the viewpoint of productivity, and torsional processing enhances linearity to improve the workability of the tire cutting process, and ultimately has an advantage in terms of tire uniformity.

In addition, since it has a two-dimensional gear waveform, it is possible to secure a proper elongation of fracture so as to mitigate impact transmitted from a road surface impact during tire travel, thereby exhibiting an excellent ride quality. In addition, the steel wire breaks out of the tread There is an advantage that it is possible to prevent the so-called core migration which gives a lethal damage to the tire.

Further, since only one single-stranded wire is used, it is advantageous in weight reduction of the tire, there is no internal gap, rubber penetration is high, and a plurality of single-wire steel cords can be obtained by imparting twist and waveform to plural steel wires, Is expected to be a new structure as a rubber reinforcing material which is more economical than the manufacturing process of steel cord and single wire steel cord.

In addition, the present invention can be easily manufactured by attaching a simple torsion and wave form imparting device to a drawing machine without requiring additional additional manufacturing facilities.

These and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, which illustrate preferred embodiments of the invention.

First, the mechanical properties of the single-wire steel cord according to the present invention are suitably in the range of 270 kgf / mm 2 or more in tensile strength and 1.5 to 5.0% in elongation at break. The steel wire satisfying these conditions is a piano wire material SWRS 82A (C = 0.82%) or repeated high-speed cold drawing and patenting heat treatments with a wire rod of base steel (0.8% <C≤1.5%) to obtain higher strength. The wet drawing process is performed.

The thickness of the brass plating layer formed on the surface portion of the single-piece steel cord of the present invention is preferably in the range of 0.05 to 20 占 퐉 in order to ensure higher rubber adhesion between the steel rubber and the rubber, The range of 0.07 to 1.5 μm is most advantageous.

The copper content in the brass plating layer is preferably 55 to 70%, and more preferably, the third element Co, Fe, Ni, or the like is added to the brass plating in the range of 0.1 to 5.0% It is possible to improve the adhesion between the rubber and the steel wire, as well as to improve the corrosion resistance and the aging adhesion.

3, after the two strands of the steel wire are supplied through the supply part 21, the first twist device 22 and the second twist device 24, which rotate in opposite directions to each other, , The material itself of each steel wire is twisted, but a gear waveform is applied through the corrugated part excitation 23 in a state where a fine twist is given so that the two strands are not twisted, And wound around a take-up portion 29 through a lead-out portion 28 through a guide roller 27, which is an abdomen abutment portion for individually classifying the steel wires of the steel sheet.

However, if the rotation of the first torsion device 22 and the second torsion device 24 is too large, the disconnection at the point A where the two strands are twisted to each other due to the excessive twist, On the contrary, if the rotation is too small, uneven residual stress remains in the steel wire material itself, and the linearity is deteriorated.

Therefore, the material of the steel wire itself is twisted just before passing through the corrugated part excitation 23 by appropriately combining the rotation amounts of the first twist device 22 and the second twist device 24, but the two steel wires are twisted It is more important than ever to give a fine twist.

Therefore, the rotation ratio of the first twist apparatus 22 and the second twist apparatus 24 (second twist apparatus / first twist apparatus) is preferably 0.1 to 1.5 times.

On the other hand, since the embodiment of the present invention obtained through the above manufacturing process simultaneously receives the fine twist by the combination of the first twist apparatus 22 and the second twist apparatus 24 and the bending deformation by the gear waveform simultaneously, And is rotated in a substantially periodic three-dimensional shape along the longitudinal direction.

Figs. 4 and 5 explain the shape in which the two-dimensional waveform of the embodiment of the present invention rotates along a cycloid curve in a substantially periodic three-dimension along the longitudinal direction.

4, the steel cord 100 of the embodiment of the present invention is composed of a two-dimensional waveform having a pitch p ₂ of 5 mm and a wave height h of 0.27 mm (wave height H - small diameter d) As described above, the two-dimensional waveform rotates in a substantially periodic three-dimensional shape.

Here, the pitch p ₂ of the two-dimensional waveform is determined by the circumferential pitch of the corrugated portion 23, and the magnitude of the corrugation h is influenced by the corrugation of the corrugated portion 23 imparted during manufacturing, The amount of the corrugated portion 23 plays a major role in adjusting the cutting force and the elongation at break of the steel wire.

On the other hand, a form in which the two-dimensional waveform of the steel wire rotates along the hypercyloid curve in a substantially periodic three-dimensional shape along the longitudinal direction is shown in detail in FIG.

Fig. 5 is a graph showing the results obtained by fixing a specimen of the embodiment of the present invention in a longitudinal direction (X direction) by applying a slight tensile force such that the waveform shape of the specimen does not substantially change, Size and shape.

That is, the shape in which the two-dimensional waveform rotates three-dimensionally in a substantially periodic manner in the longitudinal direction is a front view and a plan view.

The two-dimensional waveform of the embodiment of the present invention is rotated by 360 degrees in the clockwise direction, that is, once by a predetermined length F1. At this time, the length of the period F l, which rotates by 360 °, is about 840 mm, which corresponds to about 2100 times of the small diameter (d).

The reason why the length of the period F1 in which the two-dimensional waveform rotates in a three-dimensional shape along the longitudinal direction is considerably large is that the material itself of the steel wire is twisted as described above, This is due to the feature of the manufacturing method of the present invention which gives a fine twist.

At this time, the length of the three-dimensional rotation period F 1 becomes shorter as the rotation of the first twist apparatus 22 and the second twist apparatus 24 that impart twist becomes larger, and conversely, the rotation becomes shorter as the rotation becomes shorter.

5, Fℓ1, Fℓ2, Fℓ3, and Fℓ4 indicate the length of a period in which the two-dimensional waveform rotates by 90 °. On the other hand, the direction in which the two-dimensional waveform rotates three-dimensionally is determined by the rotating direction of the first twist apparatus 22, and can be arbitrarily changed.

In order to express the shape until the two-dimensional waveform rotates 360 degrees along the longitudinal direction, the sectional views A-A ', B-B', C-C ', and D Observing -D 'and E-E', the trajectory of the two-dimensional waveform, rather than the straight line, forms a hypercycloid curve along the inside of the embodiment of the present invention.

FIG. 6 shows a cycloid curve drawn while the two-dimensional shape of the embodiment of the present invention rotates in a three-dimensional shape.

In Fig. 6, F? Represents the three-dimensional circumferential length of the two-dimensional waveform (the distance up to 360 占 rotation)

Fh: code pitch of three-dimensional helical shape, P2: pitch of two-dimensional waveform

h: wave height of two-dimensional waveform, d: small diameter (= 0.4m)

α: The unit angle at which the two-dimensional waveform rotates along the hypercycloid curve

     (Angle between F0 and F1)

d0 is the diameter of the inscribed circle formed by the two-dimensional waveform in the hypercyloid curve,

n = 840 / P2 = 840/5 = 168, rotation angle? = 360 / n = 360/168?

F? = F0 + F1 + F2 +? Fn = 5? 168 = 840 mm

Fh = (h + d) = (0.27 + 0.4) = 0.67, and d0 = 0 to 0.5 mm.

The results of the physical properties of the tire specimens of the present invention obtained by the above-described manufacturing process and technical construction and the specimens of the conventional and comparative examples are shown in Table 1 below.

 O: Good, X: Bad

The conventional example 3x0.30 HT of Table 1 is a twisted cord in which three strands of a circular cross section having a diameter of 0.30 mm are twisted to the right (S curve) at a pitch (twist length) of 14 mm, whereas the comparative example is a steel cord It is a 0.40mm UT single wire obtained fresh from the last wet drawing process of cord manufacturing process. The embodiment of the present invention was produced through a technical configuration in which a twist and a gear waveform were imparted simultaneously to a 0.40 mm UT wire.

In the above table, the adhesive strength of each cord after the aging period of one week under the influence of heat or salt including the initial rubber adhesion force after vulcanization according to the American Standard Test Method (ASTM 2229) was compared and examined. Is the relative index obtained by dividing the rubber adhesive force for the entirety of the steel wire which can contribute to the adhesion and converting it into the adhesive force per unit area purely, and comparing the case of the conventional example (twisted cord)

The linearity is expressed in mm by measuring the degree of bending (arc height) of the specimen at an interval of 400 mm.

The bending stiffness was measured by 3-point bending tester.

As shown in the table, the embodiment of the present invention has much lower unit weight than the conventional twisted steel cord (conventional example), so that the steel cord use weight of the tire can be reduced at the same time.

In addition, the mechanical properties including the elongation at break show similar or somewhat improved characteristics as compared with the twisted cord. In particular, it can be seen that the linearity is much superior to the comparative example, which is a single wire without twist or wave form. This is because the single wire steel cord of the present invention is deformed by the torsional stress based on the central axis with respect to the traveling direction thereof, and the linearity is improved.

In addition, the arc height could be reduced to within the control range of general codes (30 mm / 400 mm). In general, the straightness of the steel cord is associated with so-called buckling defects in which the rubber topping sheet twists or warps in the calendering process of the tire manufacturing process. The embodiments of the present invention can ensure good linearity, The productivity can be improved.

In addition, since the embodiment of the present invention has a two-dimensional gear waveform, there is an advantage that it is possible to prevent a so-called &quot; core migration &quot; in which the steel wire breaks out of the rubber due to repeated bending movements during running of the tire and causes fatal damage to the tire.

It can be seen that the bending stiffness of the embodiment of the present invention is much higher than that of the conventional twisted cord, which prevents the fine movement between the belt and the tread when used as a reinforcing material of the belt, thereby greatly increasing the life of the tread wear.

In the examples and comparative examples of the present invention, the rubber adhesive strength after initialization and aging is improved by about 20% in comparison with the conventional example (twisted cord), which means that in the case of a single steel wire, In particular, in the embodiment, the degree of improvement of the rubber adhesive force and the rubber penetration degree are further increased by giving a waveform.

As can be seen from the table, the embodiment of the present invention can reduce the manufacturing cost because the twisting process can be omitted compared to the conventional wire-type steel cord manufacturing process, and without requiring additional additional manufacturing equipment, It can be easily produced by attaching a simple torsion and waveform imparting device, so that it is possible to provide a more economical steel cord.

1 is a schematic view for explaining a method of manufacturing a conventional steel cord,

Figure 2 is a schematic view of a conventional steel cord made by Figure 1,

3 is a schematic view for explaining a method of manufacturing a steel cord according to an embodiment of the present invention,

4 is a schematic view showing a steel cord according to an embodiment of the present invention,

5 is a schematic view for explaining the three-dimensional rotation of the steel cord in the embodiment of the present invention,

Fig. 6 is a schematic view for explaining a hypercrocode curve applied to the steel cord of the embodiment of the present invention. Fig.

Claims (11)

Assuming mutually orthogonal X-Y-Z 3-axis coordinates, A single-wire steel cord made of a single strand wire, wherein a trajectory shape in which a two-dimensional waveform is formed in the XY plane in the longitudinal direction along the X axis and in which the two-dimensional waveform periodically rotates three- Wherein the reinforcing member is moved along the hypocyloid curve. 2. The method according to claim 1, wherein when the three-dimensional circumferential length of the two-dimensional waveform is F (mm) and the diameter of the steel cord is d (mm) Wherein the three-dimensional circumferential length (F 1) of the two-dimensional waveform is 500 d <Fℓ <3000 d. 2. The linear cord according to claim 1, wherein the cord diameter (Fh) of the three-dimensional trajectory shape is 0.1 + d <Fh <1.0 + d, where d Single steel cord for excellent rubber reinforcement. 2. The method according to claim 1, wherein the range of the unit angle (angle between F ₀ and F ₁ ) where the two-dimensional waveform rotates along the three-dimensional hypocycloid curve is 0.5 ° to 30 °. Single steel cord for rubber reinforcement. The single-piece steel cord for reinforcing rubber according to claim 1, wherein the pitch interval (P ₂ ) of the two-dimensional waveform is 2d to 350dmm. The steel cord according to claim 1, wherein the wave height (h) of the two-dimensional waveform is 0.02 d to 10 dmm. The single-steel cord for reinforcing rubber according to claim 1, wherein the linearity (mm / 400 mm) is in the range of 0 to 60 mm and the linearity is excellent. The steel cord according to claim 1, wherein the steel cord has a small diameter of 0.08 to 1.0 mm, a carbon content of 0.7 to 1.50 weight%, and a tensile strength of 270 to 500 kgf / mm 2. The steel cord according to claim 1 or 2, wherein a brass plating layer is formed on the surface of the single-wire steel cord to a thickness of 0.05 to 20 탆. After the plurality of strands of the steel wire are supplied through the respective supply portions 21, the material itself of each steel wire is twisted successively through the first twisting device 22 and the second twisting device 24 which rotate in opposite directions A guide waveform 27 is provided through the corrugated part excitation 23 in a state in which the strands are twisted so that they are not twisted to each other and the guide roller 27, And winding the same through a take-up portion (29) through a lead-out portion (28), thereby manufacturing a single steel cord for rubber reinforcement excellent in linearity. The method according to claim 10, wherein the rotation ratio of the first twisting device and the second twisting device is 0.1 to 1.5 times the rotation ratio (second twisting device / first twisting device). .

Images