KR100415971B1 - Single wire steel cord of vehicle tire - Google Patents

Abstract

Provided is a disconnected steel cord of a vehicle tire that has high durability and exhibits a good ride comfort, and which can realize light weight of the tire.

According to the present invention, a single-wire steel cord having two flat surfaces facing each other by flattening of the annular wire and two circular curved surfaces facing each other has a flatness ratio D / W of the long diameter D and the long diameter W in a range of 0.50-0.95, Moreover, it is wave-filled at least in the direction of a radial direction, and is used embedded in a tire belt part so that one flat surface may face a tire ground surface side.

Description

SINGLE WIRE STEEL CORD OF VEHICLE TIRE}

In recent years, as a part of the promotion of global warming prevention, the exhaust gas total regulation is demanding, and the fuel efficiency of the automobile is being improved, and the movement to reduce the thickness of the rubber part has been vigorous for the purpose of reducing the tire weight. For this reason, great expectations are raised from the automobile industry regarding the development of steel cords as tire reinforcements. Since then, in order to improve the global environment, it is urgent to develop a single-wire steel cord that emphasizes tire performance, especially cornering power and ride comfort, while making tires thinner and lighter.

The radial tire belt layer for passenger cars is installed between the tread and the carcass, and is a circumferentially extending belt that tightens the carcass like a rim and increases the tread rigidity. The function of this belt layer is indispensable for the tire to support the weight and at the same time has the role of exerting power in cornering.

As the tire belt layer, a steel cord having a 1 × n structure obtained by twisting a plurality of strands together is generally used. Such a stranded steel cord has high rigidity, but on the other hand, on the uneven road with a rough road surface, the repulsive force of the tire is too strong, resulting in poor riding comfort. In addition, it is easy to create cracks on the tread surface, and rainwater or the like penetrates into the tire from the cracks, and the cord wires are corroded early. In addition, when the tire is deformed or vibrated, there is a problem in that the cord wires are fatigue-deteriorated significantly by generating a so-called fretting wear in which the twisted wires rub against each other and wear.

In order to solve these problems, it is proposed to use a single-wire steel cord made of a round wire instead of a steel cord of a stranded wire structure for the belt layer of a tire. This is because the single-wire steel cord is more plastic than the steel cord of the stranded structure.

However, the conventional single-wire steel cord of the annular wire structure or the steel cord of the stranded wire (1 × n) structure has the following problems.

Two characteristics are used for evaluating the performance of steel cords. For example, "kill" and "arc height" are used. The "kill" is used to evaluate the rotational torque inherent in the cord itself. One of the code characteristics. "Arc height" is one of the cord characteristics used for the linearity evaluation of a steel cord. If the keel is distorted or biased or the arc height is too large, the calendering step of the tire manufacturing process is to lay steel cords side by side on a thin rubber sheet and cover another thin rubber sheet between the rubber sheets. This is because a defect such as twisting or swelling occurs in the calender sheet in the step of inserting a steel cord).

However, in a conventional twisted wire structure (1 × n) cord or an annular wire disconnection cord, a change in kill or arc height is caused by mechanical factors such as wire material, drawing machine, or stranded wire. This is easy to occur. In particular, kills are so variable that inspections are carried out for each product even at the general level of quality assurance.

(1) kill

As the performance of the steel cord used for the tire, in particular, the evaluation of the rotational torque of the steel cord, that is, the rotational torque (kill) inherent in the cord itself, is important. Hereinafter, the kill will be described with reference to FIG. 1.

The measuring method of the kill is taken out from the spool 1 by L1 (= 6 m), as shown in Fig. 1, while fixing the cord terminal portion 2c of the finished spool 1 with an L-shape and fixed with a fixture (not shown). After that, the number of revolutions of the cord 2 is counted by releasing the cord terminal 2c from the fixture. In the case of normal S twisting, the case of rotating in the same direction (clockwise) as the twisting direction is called a positive kill (+), and the case of rotating in the opposite direction of the twisting direction (counterclockwise) is called a negative kill (-). . In general, the kill is good if the number of revolutions within ± 2 revolutions, the code is practically no problem.

(2) arc height

As a performance of the steel cord used in the tire belt portion, cord linearity evaluation (arc height) in a non-constrained state is important. Hereinafter, the arc height will be described with reference to FIG. 2.

As shown in Fig. 2 (b), the cord 2 cut into the length L2 (= 400 mm) shown in Fig. 2 (a) has the height of the arc formed by the cord 2 in the state in which both ends are brought into contact with the plate 3. AH corresponds to arc height. Usually, the arc height AH is 30 mm or less, and the cord is practically no problem.

(3) cornering power and ride comfort

One of the performances required for steel radial tires is that the steering wheel bends well at high speeds, i.e., the cornering power for risk avoidance is high. Moreover, although the cord with high rigidity has been used conventionally, since a tire receives a vibration up and down in front about the unevenness | corrugation of an unpaved road surface, ride comfort falls. The performance required for the steel cord for reinforcement of the tire belt layer in this way is two of the durability in the transverse direction at the cornering and the excellent ride comfort at the time of running. Combining these two capabilities is important for later steel cords.

(4) thinner tire rubber thickness

In recent years, automobiles have tended to be designed for low fuel economy vehicles, which have put importance on measures to prevent global warming. Accordingly, tires have been required to be lighter in weight. However, in the conventional stranded wire cord or the annular wire break cord, there is a limit to the improvement to reduce the rubber thickness of the tire.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single wire steel cord of a vehicle tire used for reinforcement of various vehicle tires, and more particularly, to a single wire steel cord of a vehicle tire embedded in a tire belt portion.

1 is a schematic diagram for explaining the kill of a single-wire steel cord.

2 (a) is a view showing a steel cord cut to a predetermined length, Figure 2 (b) is a view for explaining a method of measuring the arc height of the steel cord.

3 is a process chart showing a method for manufacturing a single-wire steel cord according to the first embodiment of the present invention.

(A) is a schematic diagram which shows the manufacturing line of the single wire steel cord of 1st Embodiment, (b) is an overview schematic diagram of the single wire steel cord in each process, (c) is a cross sectional view of the single wire steel cord in each process. to be.

Fig. 5 is a front view showing the main part of the flattening device (drive roll rolling device).

It is a side view which shows the principal part of the flattening apparatus (drive roll rolling apparatus).

It is a front view which shows the outline | summary of the arc wave insertion apparatus (pin roll processing apparatus).

It is a side view which shows the outline | summary of the arc wave insertion apparatus (pin roll processing apparatus).

It is a partially enlarged view which shows the principal part of the circular wave insertion device (pin roll processing apparatus).

Fig. 10 (a) is a schematic diagram of the enclosed single-wire steel cord (0.25HT) of the gear crimp wave, (b) is a schematic diagram of the enclosed single-wire steel cord (0.25HT), and (c) the gear crimped wave single-wire steel cord ( 0.30HT), (d) is an overview diagram of a circular arc sheathed single wire steel cord (0.30HT), (e) is a schematic diagram of a gear crimped waved single wire steel cord (0.35HT), and (f) is a circular wave insertion broken line Schematic diagram of the steel cord (0.35HT).

(A) is a cross-sectional view of the single-wire steel cord (cord of type 1) of 1st Embodiment, (b) is a schematic diagram of the single-wire steel cord (cord of Type 1) of 1st Embodiment, (c) is 1st It is a cross-sectional schematic diagram of the steel radial tire which embedded the single-wire steel cord (cord of Type 1) of embodiment.

It is process drawing which shows the manufacturing method of the single wire steel cord which concerns on 2nd Embodiment of this invention.

(A) is a schematic diagram which shows the manufacturing line of the single wire steel cord of 2nd Embodiment, (b) is an overview schematic diagram of the single wire steel cord in each process, (c) is a cross-sectional view of the single wire steel cord in each process. to be.

(A) is a cross-sectional view of the single-wire steel cord (cord of type 2) of 2nd Embodiment, (b) is an overview schematic diagram of the single-wire steel cord (cord of Type 2) of 2nd Embodiment, (c) is a It is a cross-sectional schematic diagram of the steel radial tire which embedded the single-wire steel cord (cord of Type 2) of 2nd Embodiment.

(A) is a cross-sectional view which shows the single wire steel cord of the comparative example 1, (b) is a schematic diagram which shows the single wire steel cord of the comparative example 1. FIG.

(A) is a cross-sectional view which shows the single wire steel cord of the comparative example 2, (b) is a schematic diagram which shows the single wire steel cord of the comparative example 2. FIG.

17 is a cross-sectional view showing each of single-wire steel cords of Examples and Comparative Examples for explaining cord stiffness.

It is a perspective view which shows the test piece used for the belt durability test.

19 is a cross sectional view of a test piece used for a belt durability test.

20 is a schematic diagram showing a belt durability tester.

An object of the present invention is to provide a disconnected steel cord of a vehicular tire that has a large cornering power, an excellent ride comfort, and a thinner tire rubber.

In order to increase the durability in the transverse direction during cornering, it is important to use a cord having a high transverse rigidity (in-plane bending rigidity) E1. In addition, it is effective to use a cord with longitudinal rigidity (outside surface flexural stiffness) E2 in order to flexibly prevent the unevenness of the tire ground surface and to reduce the rugged ride feeling felt by the occupant to improve the ride comfort. Do.

In order for the steel cord of the belt portion to have high durability and plasticity, it is important that the in-plane bending stiffness E1 is larger than the out-of-plane bending stiffness E2 (E1> E2) and has anisotropy in rigidity.

However, in the case of a conventional stranded wire cord or an annular wire break cord, there is almost no difference between the transverse stiffness E1 and the longitudinal stiffness E2 even if two-dimensional insertion (gear crimp) or three-dimensional insertion (spiral) is performed. For this reason, it cannot satisfy both the durability in the horizontal direction at the time of cornering, and the training ability of the riding comfort in a longitudinal direction. In other words, if the emphasis is on the durability, the ride quality is worse. On the other hand, if the emphasis is on the riding comfort, durability is not obtained.

By the way, it is proposed to use the single wire steel cord as described in Unexamined-Japanese-Patent No. 7-1915 for the belt layer of a tire instead of the single wire steel cord which consists of an annular wire. This single-wire steel cord is a flattened wire, for example, a two-dimensional wave encased process using the apparatus described in Japanese Patent Application Laid-Open No. 10-25680, and has excellent adhesion with rubber and high flexural rigidity. When used in the belt part, excellent steering stability can be obtained. However, this single-wire steel cord is insufficient to reduce the thickness of the tire rubber and the ride comfort is not necessarily good.

Therefore, the present inventors have completed the present invention described below as a result of research for reducing the thickness of the tire, reducing weight, and improving performance.

In the present invention, the flattening ratio D / W of D for W representing the diameter of the cross section of the flattened annular wire and the long diameter of the cross section of the flattened annular wire is in the range of 0.5-0.95. Wherein at least one flat surface is embedded in the tire belt portion so as to face a portion of the tire in contact with the ground, and one flat surface positioned between the two flat surfaces is a tire ground. It is characterized by being used embedded in the tire belt portion to face the side.

Such a single-wire steel cord is used by being embedded in the tire belt part such that one flat surface faces the tire ground plane side. (A) The flat ratio D / W of the diameter D and the long diameter W is in the range of 0.50-0.95. And a step of flattening the annular wire and (b) a step of inserting a wave in the direction of the radial direction of the annular wire flattened in the step (a).

Moreover, it is preferable to have the long diameter wave insertion process of putting a wave in an annular wire in the direction orthogonal to the wave direction in the said wave length wave insertion process (b) before the said process (a). In this case, it is preferable that the flat ratio D / W is in the range of 0.80-0.95 in the step (a).

In single-wire steel cords (cords of type 1) in which the crimp wave is inserted only in the direction of the seam, the flat ratio D1 / W1 is preferably in the range of 0.50-0.95.

The reason why the upper limit of the flatness ratio D1 / W1 is 0.95 is that if the wire is closer to the circle beyond 0.95, the effect of reducing the rolling (rolling torque) due to rolling cannot be seen, and there is no difference in the stiffness in the long diameter direction and the simple direction. Because.

On the other hand, the lower limit of the flatness ratio D1 / W1 is 0.50 as a wire for steel cord using 0.82% of high carbon steel, and the wire having a lengthening operation has a high tensile strength of about 300kgf / mm ² , so the flatness ratio is 0.50. This is because cracking may occur in the wire after rolling in the case of high flatness rolling below.

It is preferable that the maximum value of the height F1 of the wave insertion in the direction of the flow direction is 0.3 mm. This is because if the wave filling height F1 is made too large, the rubber portion becomes thick and deviates from the purpose of weight reduction of the tire.

On the other hand, it is preferable to make the minimum value of the wave insertion height F1 of a grazing direction into 0.05 mm. This is because a wave height of at least 0.05 mm is required to reduce the arc height AH to 30 mm or less.

In addition, the wave pitch P1 is preferably set to 2-20 mm. This is because the wave insertion pitch becomes a practical range within this range.

"Wave insertion" refers to forming a wire in a two-dimensional or three-dimensional shape by applying a stress to the wire beyond the elastic limit.

In addition, "crimp wave insertion" here means forming a wire in the two-dimensional shape which repeats the same wave in one plane. Representative of this crimp wave insertion is a gear crimp wave insertion process in which a wire is sandwiched and molded between a pair of gears. Moreover, crimp wave insertion also includes the process which pushes a spiral wire of a three-dimensional shape from side to a two-dimensional shape.

In addition, "arc wave insertion" means here shape | molding a wire in the two-dimensional shape which consists only of the combination of the smooth continuous curve which does not contain a straight part in one plane. A typical example of this arc wave insertion is a pin roller wave insertion process in which a wire is sandwiched and molded between a pair of pin rollers.

In addition, the code in which the wave is inserted only in the radial direction (the code of type 1) has a relatively low setting area, so when an extension that cannot be covered by this type 1 requires an extension, the wave is moved in both directions. Use the code you have inserted (type 2 code).

The code flat ratio D2 / W2 ((D2: flat wire diameter) / (W2: flat wire diameter) is preferably in the range of 0.80-0.95. The upper limit of the flatness ratio is 0.95. This is because if the wire is closer to the circle than 0.95, the effect of reducing the kill (rotation torque) due to rolling is not seen, and there is no difference in the stiffness in the long diameter direction and the simple diameter direction. The reason for this is that in the type 2 cord, after extending the line, the long-length crimping, the driving roll rolling, and the three-way crimping are performed. Therefore, the strength reduction caused by the damage to the wire during rolling is prevented. For that.

In the code of Type 2, it is preferable that the maximum value of the crimp wave insertion height F3 in the diametric direction is 0.3 mm, and the crimp wave insertion height F2 in the long diameter direction is in the range of 0.05-0.5 mm. The reason why the maximum value of the wave filling processing height F3 in the flow direction is 0.3 mm is because when the wave filling height is made too high, the rubber thickness of the tire becomes thick, which deviates from the weight reduction purpose. The reason why the maximum length of the wave insertion height F2 in the long direction is 0.5 mm is that if the wave insertion height is too large, the extension of the cord becomes excessively large and the mountain and valley face each other depending on the shape of the cords. It is because unevenness of the space | interval of a liver becomes remarkable and it is not preferable. The minimum value of the wave insertion height F2 in the long diameter direction is 0.05 mm because the arc height AH cannot be reduced to within 30 mm (passed judgment) if the wave insertion height is made smaller than this.

It is preferable that wave insertion pitches P2 and P3 be 2-2.0 mm in both a long diameter direction and a simple diameter direction. This is because the wave insertion pitch becomes a practical range within this range. However, the set height of the wave pitch is set to the integer length of the pitch length P2 in the long diameter direction with respect to the pitch length P3 in the long direction in order to eliminate the pitch nonuniformity in the long diameter direction and the simple diameter direction.

Moreover, it is preferable to use 300-380 kgf / mm class ² high tensile strength steel wire of tensile strength for a constituent wire. This is because the tensile strength of the wire needs to be 280 kgf / mm ² or more in order to obtain the desired breaking strength of the single-wire steel cord. On the other hand, when the tensile strength of the wire exceeds 400 kgf / mm ² , the wire becomes weak and breakage easily occurs.

Moreover, it is preferable to use the high tensile steel wire of 0.75-0.95 weight% for carbon in a constituent wire. This is because the carbon content of the wire needs to be 0.7% by weight or more in order to obtain the desired breaking strength of the single-wire steel cord. On the other hand, if the carbon content of the wire exceeds 1.0% by weight, the wire is weakened and easily causes disconnection.

Hereinafter, various preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Using the manufacturing method shown to FIG. 3 and FIG. 4 (a), the single-wire steel cord 2A of type 1 shown to FIG. 4 (b), (c) and 11 (a), (b) was produced, and this single-wire steel cord The steel radial tire 10A shown to FIG. 11 (c) was manufactured using 2A. Moreover, using the manufacturing process shown to FIG. 12 and FIG. 13 (a), the disconnected steel cord 2B of the type 2 shown to FIG. 13 (b), (c) and FIG. 14 (a), (b) was produced, and this disconnection is performed. The steel radial tire 10B shown to FIG. 14 (c) was manufactured using the steel cord 2B.

Each will be described in detail below.

(Example 1 and Example 2: Type 1 Cord)

A carbon content of 0.82 ± 0.02% by weight steel wire was prepared by wire (step S1). The wire was heated and held at 950 ° C. for 30 seconds in a heating furnace, and then cured under conditions of heating and holding at 550 ° C. for 8 seconds in a flow furnace using sand (Step S2). %, Zn37% by weight of the surface of the element wire was brass-plated (step S3), the plated steel wire was stretched with a line stretcher 5, the tensile strength was set to high tensile steel wire wire 2 of the range 308-312kgf / mm ² (step S4) ). The diameter of the wire 2 after the stretching was 0.40 mm. In addition, the amount of brass plating per kg of wire is about 4 g.

Subsequently, the circular wire 2 was sent to the driving roll rolling device 7, and it was crushed with a pair of upper and lower rolling rolls 71 and 72 to make a flat wire 2a of 0.30 mm × 0.46 mm (diameter × long diameter) size (process S5). ).

The driving roll rolling apparatus (part evaluation air) 7 is demonstrated, referring FIG. 5 and FIG. The partial evaluation air 7 has a pair of upper and lower caliber rolls 71 and 72. The upper roll 71 is connected to the drive shaft 73 which is rotationally driven by the motor 78, and the lower roll 72 is connected to the rotation shaft 74 which is rotationally driven by the motor 79. The cog wheels 76 are provided on the drive shafts 73 and 74, and the cog wheels 76 mesh with the cog wheels 77 provided on the rotary drive shafts of the respective motors 78 and 79, respectively. On the circumferential surface of each roll 71 and 72, the predetermined | prescribed recessed caliber 71a and 72a are formed, respectively. Each of the roll shafts 73 and 74 is supported by the brackets 73b and 74b via the bearings 73a and 74a. The lower bracket 74b is fixed to the frame (shown) of the rolling apparatus, and the upper bracket 73b is connected to the lower bracket 74b by the adjusting screw 75. Turning the adjusting screw 75 raises and lowers the upper roller 71 together with the upper bracket 73b, and changes the gap between the upper roller 71 and the lower roller 72. In addition, a hydraulic cylinder mechanism may be used for the roll gap adjustment mechanism instead of the adjustment screw 75.

The round wire 2 meshes between the calibers 71a and 72a of the up and down rolls 71 and 72, and is pressed and crushed up and down to become the flat wire 2a. Subsequently, the flat wire 2a was sent to the wave-feeding machine 8, and this was wave-wrapped in the lamellar direction by the pin rolls 83a and 83b to obtain flat cord 2A waved in one direction (step S6).

The wave insertion machine 8 is demonstrated, referring FIG. 7 and FIG. The upper and lower pairs of large rollers 82a and 82b are housed in the housing 81 of the wave insertion machine 8. The housing 81 has an inlet guide 85 and an outlet guide 86. The wire 2 is introduced into the housing 81 via the inlet guide 85, passes between the large rollers 82a and 82b, and is fed out of the housing 81 via the outlet guide 86.

As shown in FIG. 9, holder 87a, 87b is provided in the outer periphery of large rollers 82a, 82b at equal pitch intervals, and small diameter pin rolls 83a, 83b are provided in each holder 87a, 87b, respectively. The pin rolls 83a (83b) and the pin rolls 83a (83b) adjacent to each other are provided such that there is almost no gap. The upper roller 82a is coaxially connected with the cogwheel 84a, and the lower roller 82b is coaxially connected with the cogwheel 84b. The upper and lower cogwheels 84a and 84b mesh with each other. The upper and lower rollers 82a and 82b are reliably rotated synchronously without causing slippage between the upper and lower rollers 82a and 82b by both gears 84a and 84b.

When the wire 2 is engaged between the large rollers 82a and 82b, the wire 2 is bent by the upper and lower pin rollers 83a and 83b and waved in a smoothly continuous arc shape as shown in Figs. In this case, the diameters D of the pin rolls 83a and 83b must be sufficiently larger than the wire diameter d. The diameters D of the pin rolls 83a and 83b are preferably in the range of 5-50 times the wire diameter d.

Alternatively, the wire 2 may be subjected to a two-dimensional crimp wave inserting process using the gear crimping machine disclosed in Japanese Patent Application Laid-Open No. 10-25680 instead of the circular wave inserting machine 8. The external appearance of the wire 2K wave-processed by such a gear crimping machine is shown to FIG. 10 (a), (c), (e).

As shown in Table 1 and Figs. 11 (a) and (b), the code 2A of Examples 1 and 2 (type 1) has a wave insertion height F1 of 0.1 mm, 0.1 mm, and a diameter D1 of 0.30mm, 0.36mm, long diameter W1 is 0.46mm, 0.44mm, flat ratio D1 / W1 is 0.65, 0.82, wave insertion pitch P1 is 6mm, 6mm.

Further, the cord 2A was wound on the reel of the winding machine 9, this reel was installed on the supply side of the cutting line, and the cord 2A was cut to a predetermined length by a cutter (not shown) (step S7). The length of the cutting cord 2A is 200 mm. As shown in Table 1, the kill of code 2A was 0-0.75 revolutions (average 0.5 revolutions), and the arc height AH was 10-28 mm (average 15 mm, 24 mm).

Codes 2A of Examples 1 and 2 (type 1) had stiffness indexes G2 of 74, 97, and stiffness indexes G1 of 149 and 114 in the long diameter direction, and stiffness ratios G1 / G2 of 2.00 and 1.18, respectively. In addition, "stiffness index" corresponded to the ratio in the case where the rigidity G3 of a round wire was made into the reference value 100, and it measured about two directions shown in FIG. In addition, code 2A of type 1 was found to have a fracture elongation in the low region of 2.5-3.5%.

The so-called calendering, in which the cutting cord 2A was laid on the raw rubber sheet in parallel at predetermined pitch intervals (step S8). In this rendering process S8, cord 2A is put side by side so that one flat surface may become parallel with a raw rubber sheet surface. In addition, since the arc height AH of the cutting cord 2A is small, it is easy to lay the cutting cord 2A side by side. The pitch spacing alongside is eg 1.2mm.

The rubber sheet is cut to a predetermined size (step S9). Two cutting sheets 12A and 14A are overlapped with each other on the belt portion of a tire-shaped rubber molded article so that the embedding cord 2A intersects each other at a predetermined angle. In addition, the rubber member 16 having the tread 18 is attached to the sheet 14A of the outer side (second layer), whereby the cord 2A is completely embedded in the rubber (step S10). In this way, the embedded molded article was heated to a predetermined temperature and integrated to obtain a tire product 10A shown in Fig. 11C (step S11).

In the tire product 10A, the cords 2A are arranged so that the part of the belt adjacent to the belt layers 12A and 14A has a predetermined interval, and are arranged side by side in an oblique direction with respect to the rotational direction of the tire. This structure hardens the stiffness E1 in the lateral direction to increase durability, and conversely, softens the longitudinal stiffness E2 to enable a soft ride.

Next, the single-wire steel cord of type 2 and its manufacturing method are demonstrated, referring FIG. 12 and FIG. 13 (a), (b), (c).

(Example 3 and Example 4: Code of Type 2)

A steel wire with a carbon content of 0.82 ± 0.02% by weight was prepared with an element wire (step S21). The wire was heated and held for 30 seconds at a temperature of 950 ° C. in a heating furnace, and then cured under conditions of heating and holding at a temperature of 550 ° C. for 8 seconds in a fluidized furnace using sand (step S22). %, Zn37% by weight of the wire surface was brass-plated (step S23), and the plated steel wire was lined with a straightener 5 to obtain high tensile steel wire 2 having a tensile strength in the range of 308-312 kgf / mm ² (step S24). After stretching, the diameter of wire 2 is 0.40 mm. In addition, the amount of brass plating per kg of wire is about 4 g.

Subsequently, the wire 2 was sent to the wave engraving machine 8, and this was made into the wire 2b1 which was wave-wrapped in the long diameter direction by the pin rolls 83a and 83b, and was circular arc-wrapped in one direction (step S25). Instead of the circular wave inserting machine 8, a gear crimping machine disclosed in Japanese Patent Laid-Open No. 10-25680 may be used.

Then, the wire 2b1 was sent to flattening air 7, and it was crushed up and down by a pair of rolling rolls 71 and 72, and it was set as the flat wire 2b2 of 0.36 mm x 0.44 mm (diameter x long diameter) size (process S26). ). In addition, the apparatus shown in FIG. 5 and FIG. 6 was used for partial evaluation air 7. As shown in FIG.

Subsequently, the flat wire 2b2 was sent to the wave-feeding machine 8, and this was wave-wrapped in the direction of the bend by a pair of pin rolls 83a and 83b to obtain a flat cord 2B with circular arcs in two directions (step S27). Instead of the circular wave inserting machine 8, a gear crimping machine disclosed in Japanese Patent Application Laid-Open No. 10-25680 may be used.

As shown in Tables 1 and 14 (a) and (b), the code 2B of Examples 3 and 4 (type 2) has a wave insertion height F2 in the long diameter direction of 0.1 mm, 0.1 mm, and the simple direction, respectively. Wave insertion height F3 0.1mm, 0.1mm, diameter D2 0.36mm, 0.38mm, long diameter W2 0.44mm, 0.43mm, flat ratio D2 / W2 0.82, 0.88, long diameter wave insertion pitch P2 6.0 Wave insertion pitch P3 of mm, 6.0 mm, and a flow direction is 3 mm and 3 mm.

Further, the cord 2B was wound on the reel of the winding machine 9, this work was installed on the cutting line supply side, and the cord 2B was cut to a predetermined length by a cutter (not shown) (step S28). The length of the cutting cord 2B is 200m. As shown in Table 1, the kill of code 2B was 0-0.75 revolutions (average 0.5 revolutions), and the arc height AH was 8-20 mm (average 12 mm and 17 mm).

Code 2B of Type 2 had stiffness indexes G2 of 94 and 97 in the simple direction, 111 and 109, and stiffness ratios G1 and G2 of 1.18 and 1.12, respectively. In addition, the "stiffness index" corresponded to the ratio in the case where the rigidity G3 of a round wire was made into the reference value 100, and it measured about two directions shown in FIG. In addition, it was found that code 2B of type 2 had a fracture elongation in a high region of 3.0 to 5.0%.

So-called calendering was performed in which the cutting cords 2B were placed side by side on the raw rubber sheet in parallel at predetermined pitch intervals (step S29). In this rendering process S29, cord 2B is placed side by side so that one flat surface is parallel with the raw rubber sheet surface. In addition, since the arc height AH of the cutting cord 2B is small, it is easy to lay the cutting cord 2B side by side. Pitch pitch is eg 1.2mm.

The rubber sheet is cut to a predetermined size (step S30). Two cutting sheets 12B and 14B are superimposed on a tire-shaped rubber molded belt part so that the embedding cord 2B intersects each other at a predetermined angle. In addition, a rubber member 16 having a tread 18 is attached to the outer (second layer) sheet 14B, whereby the cord 2B is completely embedded in the rubber (step S31). The molded article thus assembled was heated to a predetermined temperature and integrated to obtain a tire product 10B shown in Fig. 14C (Step S32).

The flat wire section flatness ratio ((D2: flat wire diameter) / (W2: long wire diameter)) applied to Type 2 was 0.80-0.95.

The upper limit of the flat ratio is 0.95 because when the flat ratio exceeds 0.95 and is close to a round circle, the effect of reducing the rolling (rolling torque) due to rolling cannot be seen, and a difference occurs in the stiffness in the long diameter direction and the simple diameter direction.

In addition, the lower limit of the flatness ratio is higher than 0.80 and 0.50 of the type 1 because the type 2 is crimped more than the type 1 because the liner is subjected to three times of long diameter crimping + driving roll rolling + short diameter crimping. This is because the number of times of processing increases once, and the purpose is to prevent a decrease in strength due to damage to the wire in rolling.

The wave height in the long diameter direction was in the range of 0.05-0.5 mm. The maximum value of the wave height in the long direction is 0.5 mm. If the wave insertion height is too high, the elongation becomes excessively large, and the mountains and valleys face each other depending on the lines of the cords, resulting in an uneven gap between the cords. This is because it is not preferable.

The maximum value of the wave filling processing height in the direction of flow is 0.3 mm because the rubber of the tire becomes thick when the wave filling height is made too high, and it deviates from the purpose of weight reduction. In addition, the minimum value is 0.05 mm because the arc height AH cannot be reduced to a standard of 30 mm or less unless the wave filling processing in the water direction is at least this much.

The cord of the type 2 has good quality close to zero at 0.5 revolutions even though arc height AH (linearity) is good at 12 mm and 17 mm.

In addition, the tire in which the type 2 is embedded can have the same expectation as the type 1 with respect to the durability of the lateral rigidity and the soft riding comfort effect of the longitudinal ductility.

Next, the single-wire steel cord of the comparative example 1-3 is demonstrated, referring FIG. 15 (a), (b) and FIG. 16 (a), (b).

(Comparative Example 1: Ring Line Two-dimensional Crimp Wave Insertion Code)

Using the same wire as that of the above-described Example, a single-wire steel cord 2C containing a round-line two-dimensional crimp wave of cross sections shown in Figs. 15A and 15B was produced as Comparative Example 1. As shown in Table 1, code 2C of Comparative Example 1 had a diameter D of 0.40 mm and a wave insertion pitch P of 6 mm. The stiffness index G2 in the radial direction is 100, the stiffness index G1 in the long diameter direction is 103, and the stiffness ratio G1 / G2 is 1.03. Moreover, the arc height AH (linearity) of code 2C was 39 mm, and the kill (rotation torque) was 1.0 rotation.

(Comparative Example 2: Ring 3D Spiral Machining Code)

Using the same wire as that of the above-mentioned example, a round wire three-dimensional spiral processed single-wire steel cord 2D having a cross section shown in Figs. 16 (a) and (b) was manufactured in Comparative Example 2. As shown in Table 1, Cord 2D of Comparative Example 2 has a diameter D of 0.40 mm and a spiral pitch P of 6 mm. In addition, the stiffness index G2 in the complex direction is 100, the stiffness index G1 in the long diameter direction is 100, and the stiffness ratio G1 / G2 is 1.00. In addition, the arc height AH (linearity) of code 2D was 18 mm, and the kill (rotation torque) was 0.5 rotation.

(Comparative Example 3: Round Wire Cord)

The single-wire steel cord 2 which consists of a round wire of the cross section shown in FIG. 17 using the same thing as the element wire of the said Example was made into the comparative example 3. As shown in FIG. As shown in Table 1, Ring Cord 2 of Comparative Example 3 has a diameter D of 0.40 mm. In addition, the stiffness index G2 in the simple direction is 100, the stiffness index G1 in the long diameter direction is 100, and the stiffness ratio G1 / G2 is 1.00. In addition, the arc height of the cord 2 was 45 mm, and the kill (rotation torque) was 2.5 revolutions.

The respective cords of Types 1 and 2 were produced and examined for each characteristic, and the effects of 1 to 5 described below were confirmed.

① Reduction effect of the kill (rotational torque inherent in the wire) by the piece evaluator

(a) Kill is one of the important performances for the quality assurance of steel cords. In the case of producing a single-wire steel cord with a wire cutter, it is particularly important to enable kill management with the wire cutter. Normally, measuring the kill on a ring wire after line stretching results in about 1-5 revolutions.

The present inventors confirmed that kill was reduced to near zero by flattening the ring wire. By rolling the wire on a driving roll, it is possible to stably manufacture a low-level single-wire steel cord having a kill 0-1 times, and it is possible to change the conventional inspection of all the kills by a random extraction method (regular management). This drastically reduced the inspection frequency, significantly reducing work, and making it possible to produce codes with stable kills.

(b) The flat wire shows the rigid anisotropy in which the stiffness G1 in the long diameter direction is larger than the stiffness G2 in the simple diameter direction. It was found that the stiffness G1 in the long-diameter direction and the stiffness G2 in the simpler direction of these flat wires were in the relationship of the following formula (1) compared with the stiffness G3 of the conventional ring wire.

G1> G3> G2... (One)

Since the flat cord is disposed on the belt layer of the tire so that the flat surface of the tire faces the tire ground plane, the lateral rigidity E1 of the tire is stronger than that of the conventional ring wire. As a result, the cornering power is excellent, the longitudinal rigidity E2 of the tire is reduced, and the flexibility of the entire tire is increased, so that the riding comfort is improved.

② Reduction effect of arc height AH (wire linearity) by wave insertion processing

(a) Unwrapped flat wire has a large arc height AH and is unsuitable as a cord, but the arc height AH is greatly improved by wavewise in the direction of the flat wire in the final process. Arc height AH up to 30 mm) can be reduced.

(b) The extension required by the cord was secured by applying two types of wave insertion processing.

Code 2A of type 1 is waved in the radial direction with the elongation at break being 2.5-3.5% lower region.

Code 2B of type 2 is waved in the direction of the long diameter and the simple diameter, and the fracture elongation is in the high region of 3.0-5.0%.

③ Thinning

By arranging the flat braided cord in which the flat surface is facing the tire ground plane side, the rubber thickness becomes thinner and the weight of the tire can be reduced compared to the single wire cord or 1 × n stranded cord made of a conventional round wire.

④ Cost Reduction

Without using any twister, the flattening air (driving roll rolling device) and wave inserting machine (pin roll processing device or gear crimp processing device) are installed in the wire stretching machine, which is the whole process of the stranded wire process, and the flattened rolling and By continuously performing wave processing, it was possible to manufacture flat break steel cords. In addition to the omission of the twisted wire step, the processing speed in the wire stretching machine is about three times higher than that of the single wire cord using the conventional twisted wire machine, and the economical cost reduction is drastically reduced.

⑤ fatigue resistance evaluation

The fatigue resistance of each single-wire steel cord was evaluated using the belt durability tester 60 shown in FIG. As shown in FIGS. 18 and 19, the test piece 90 includes a sample layer in which five single-stranded steel cords 2 (2A, 2B, 2C, and 2D) are lined up at equal pitch intervals on the ventral side of the rubber member 91, and the rubber member. On the back of 91, there is a layer of bone filled with 5 strands of stranded cord 93 in a 2 + 2 × 0.25 line at equal pitch intervals. In addition, each dimension of the test piece 90 is 6 mm in thickness T, 12 mm in width W, and 400 mm in length L4.

The belt endurance tester 60 is equipped with a roller 61 having a diameter of 20 mm. The test piece 90 was wound around this roller 61 so that the said sample layer might become the abdomen side (inner side), and the weight 62 was provided in the both ends, respectively, and the 60 kgf load was loaded on the test piece 90. The stroke of the test piece 90 was set to 50 mm, the direction was changed in 60 cycles per minute, and this was repeated 2000 times.

After completion of the test, X-ray transmission pictures were taken by irradiating soft X-rays to the sample layer of Test Piece 90. The X-ray radiograph was observed, and the number (NBR) where the break of the cord (wire) occurred was counted for each sample. The number of test was made into 1 lot of 5 strands, and the average value evaluated.

Claims (20)

The wire of D is the diameter of the cross section of the annular wire flattened on one strand of wire having two flat surfaces and two annular surfaces, and W is the long diameter of the cross section of the flattened annular wire. Flattening ratio D / W has a range of 0.5-0.95, and forms a wave at least in the direction of the crease, and is a single-line steel cord of a vehicle tire embedded in a tire belt portion such that one flat surface faces the tire ground plane side. 2. The wire-breaking steel cord of a vehicle tire according to claim 1, wherein the wire-breaking steel cord is formed by crimping the wave only in the direction of the flow. 3. The disconnected steel cord of a vehicle tire according to claim 2, wherein the crimp forming of the disconnected steel cord has a wave loading height in the range of 0.05-0.3 mm. The wire-breaking steel cord of a vehicle tire according to claim 1, wherein the wire-breaking steel cord is crimp-formed in a wave direction and a long diameter direction. The crimp molding of the solid steel cord according to claim 4, wherein the crimp molding of the single-stranded steel cord is a single-steel of a vehicle tire having a wave insertion height in the direction of the bend in the range of 0.05 to 0.3 mm and a wave insertion height in the direction of the long diameter in the range of 0.05 to 0.5 mm. code. The solid steel cord of claim 4, wherein the flat ratio D / W of the single steel cord is in the range of 0.80-0.95. The solid steel cord of claim 1, wherein the wave pitch spacing of the single steel cord is in a range of 2-20 mm. The wire breaking steel cord of a vehicle tire according to claim 1, wherein the wave-insertion of the single-steel steel cord is made of a pin roller process having only a smoothly continuous curved portion without a straight portion in one plane. 9. The method of claim 8, wherein the wave loading of the single-steel steel cord is selected from the group consisting of a circular arc combination, a sinusoidal curve, a cycloid (spiral curve) continuous arc, a cardioid (heart curve) continuous arc, and a tracktrix (suspension linear curve) continuous arc. Or the single-wire steel cord of a vehicle tire having a smooth continuous curve formed by combining two or more. 10. The disconnected steel cord of a vehicle tire according to claim 8, wherein the wave-insertion of the disconnected steel cord comprises pin roller processing of only a simple diameter. 9. The single wire steel cord according to claim 8, wherein the pin roller processing of the single wire steel cord has a wave loading height in a range of 0.05 to 0.3 mm. 9. The single wire steel cord of a vehicle tire according to claim 8, wherein the wave insertion of the single wire steel cord is performed by pin roller processing in both directions of the radial and long diameter directions. The pin roller processing of the single-wire steel cord according to claim 12, wherein the height of the wave encasement in the bend direction is in the range of 0.05-0.3 mm, and the length of the envelopment in the vehicle tire is in the range of 0.05-0.5 mm. Steel cord. 13. The disconnected steel cord of a vehicle tire according to claim 12, wherein the flat ratio D / W of the disconnected steel cord is in the range of 0.80-0.95. The solid steel cord of claim 1, wherein the annular wire has a tensile strength in the range of 280-400 kgf / mm ² . The solid steel cord of claim 1, wherein the annular wire has a carbon content of 0.7-1.00 wt%. (delete) (delete) (delete) (delete)