KR20030061088A - Method for Drawing High Strength Steel Wire - Google Patents

Abstract

PURPOSE: A method for preventing wearing out of dies, preventing breakage of the wire rod and manufacturing high strength metal wire rod having small diameter productively by using an existing wet type slip wire drawing machine is provided. CONSTITUTION: In a method for drawing a metal wire rod(4) using a slip type wire drawing machine(1) so that diameter of finished wire becomes 0.10 to 0.40 mm, the method for drawing high strength metal wire rod comprises the processes of setting a dies slip ratio in the front part to 1 to 3%, a dies slip ratio in the middle part to 3 to 5% and a dies slip ratio in the rear part to 1 to 2%, wherein the dies slip ratio is represented as Sn={1-(1-r(n+1))/(1-R(n+1))}x100 when actual surface reduction ratio of the wire rod passing through dies No. n is rn, and mechanical surface reduction ratio at capstan(2) for drawing the wire is Rn by dividing dies schedule into front part corresponding to 50% of the total surface reduction ratio, middle part corresponding to 90% of the total surface reduction ratio and rear part corresponding to 90% or more of the total surface reduction ratio; and controlling surface reduction ratio per each dies(3) to 5 to 8% by using two dies(3) between capstans(2) in the rear part.

Description

Drawing method of high strength metal wire {Method for Drawing High Strength Steel Wire}

The present invention relates to a method for drawing a high strength metal wire, and more particularly, to a method for efficiently drawing a metal wire having a high strength thin wire in a wet drawing method using a slip type wire drawing machine.

Steel cord is made of carbon steel with 0.6 to 0.95% by weight of carbon and 0.1 to 0.4 mm in diameter, and brass plating of 0.1 to 0.4 μm is used. , 1 × 4, 2 + 2, 2 + 7, 3 + 6, 3 + 9 + 15, etc.), which is superior in strength, modulus, heat resistance and fatigue resistance to other types of inorganic and organic fibers. It is used to reinforce rubber products such as tires and conveyor belts. In recent years, the fuel economy of automobiles has been improved from the standpoint of environmental protection. That is, attempts are made to reduce the amount of steel cords used in tires by increasing the strength of steel cords having the above excellent characteristics as a tire reinforcement but having a disadvantage in that they are heavy.

For this purpose, it is necessary to improve the strength of the wires constituting the steel cord, and to improve the carbon content of the raw materials or the drawing processing of the wires, but in this case, the strength is improved, but the amount of die wear in the wire is increased. There is a problem in that disconnection is increased. Moreover, in order to achieve low cost of steel cords and to improve fresh productivity, the drawing speed must be increased, and this causes a problem in that disconnection and die wear are further promoted.

In order to improve the wear and disconnection of dies, Japanese Patent Application Laid-open No. Hei 4-322812 reduces the wire diameter until the cumulative reduction rate by the die set exceeds 90%, and the metal wire having a final wire diameter of 0.10 to 0.40 mm is fresh with a multi-stage slip type drawing machine. In a specific wire diameter area, when the work of the die is specified, that is, the speed of the line passing through the first dice is v ₁ , and the speed of the capstan drawing the line is V ₁ , the slip ratio S ₁ = [1-v _It is proposed to use a drawing machine having ₁ / V ₁ )] × 100 at 30% or less.

Meanwhile, Japanese Patent Publication No. 9-24413 In the arc method for fresh liquid by Slip sinseongi a final wire diameter of the metal wire is 0.08~0.30mm, through the peripheral speed of the final capstan V _co, any dice of fresh Pass Schedule When the speed of a metal wire is V _wn and the circumferential speed of the capstan drawing the metal wire is V _cn , the slip rate defined by S _n = (V _cn -V _wn ) / V _co is 3-8%. It is proposed a fresh method characterized by being in the range.

However, according to the method described in Japanese Patent Application Laid-Open No. 4-322812, the friction with the wire rod in the capstan becomes unstable, and the breakage caused by the vibration of the wire caused by the so-called stick slip, in which the speed of the wire rod changes intermittently, is prevented. It is difficult to do so, and the method described in Japanese Patent Application Laid-Open No. 9-24413 is difficult in terms of the cost of retrofitting a wet drawing machine in that it is possible to maintain a constant slip rate by adjusting the mechanical reduction rate of the existing drawing machine.

The present invention overcomes the problems in the prior art as described above, and aims to provide a method for producing a high-strength thin wire metal wire with high productivity by preventing wear or disconnection of a die by using an existing slip type wet drawing machine.

That is, the present invention is a method for drawing a metal wire with a slip-type drawing machine so that the diameter of the filament wire is 0.10 to 0.40 mm, the die schedule is the first half of the total reduction rate 50%, the middle portion up to 90% total reduction rate and 90% reduction rate S _n = {1- (1-r _{n +} when dividing into the latter half, where the actual reduction rate of the wire rod passing through the nth die is r _n , and the mechanical reduction rate in capstan drawing the line is R _n . ₁ ) / (1-R _{n + 1} )} × 100, set the die slip ratio to 1 to 3% in the first half, 3 to 5% in the middle half, and 1 to 2% in the second half, and between the capstans in the second half. The present invention relates to a method for drawing a high strength metal wire, wherein two dice are used to adjust the reduction rate per die to 5 to 8%.

1A is a schematic diagram showing a drawing method by a conventional isotropic reduction ratio array;

1B is a graph showing the die reduction rate and the die slip rate according to the progress of drawing in the conventional drawing method;

Figure 2a is a schematic diagram showing a drawing method using the dice array of the present invention, and

2B is a graph showing the die reduction rate and die slip rate according to the progress of the drawing in the drawing method of the present invention.

[Description of Symbols of Main Parts]

1: fresh machine

2 capstan

3: dice

4: metal wire

Hereinafter, the present invention will be described in more detail.

The present invention is a drawing method in consideration of the relationship between the mechanical reduction ratio of a wet drawing machine and the actual reduction ratio of the wire rod performed in an actual die, in the configuration of a die pass schedule for drawing a wire rod having a final wire diameter of 0.10 to 0.40 mm. If the actual reduction ratio of the wire rod passed is r _n and the mechanical reduction ratio in capstan drawing the wire is R _n , the die slip ratio S _n = (1- (1-r _{n + 1} ) / ( 1-R _{n + 1} )} × 100, so that S _n is maintained at 1 to 3% in the first half pass to the reduction rate corresponding to 50% of the final wire reduction rate, and then the total reduction rate is 90%. Until then, S _n is maintained at 3 to 5%, and then at the reduction rate of 90% or more in the latter half of the final line diameter, S _n is maintained at ₁ to 2%, and the reduction rate per die is 5 to 5 by using two dice between capstans. Pass schedule tool to reduce die wear by reducing to 8% Fresh wet method according to to provide a.

The method of the present invention reduces the pressure applied to the die due to vibration of the inlet wire at the initial rudder diameter and deformation resistance inside the wire rod by maintaining the die slip ratio S _n in the first half of the drawn wire with a total reduction rate of 50%. The initial drawing is performed without difficulty, and then the die slip ratio S _n is maintained at 3 to 5% higher in the middle of the pass where the pressure on the die is relatively lower than 90%. Uniform deformation is applied until to prevent internal defects, thereby reducing disconnection and increasing strength. In the latter part after 90% of the total reduction rate, the reduction rate of each die is reduced to 5 to 8% by using two dies between the capstans to prevent the increase of die wear due to the deformation force accumulated in the wire rod and to improve the hardness of the wire rod surface. It was set to minimize the pressure on each die and to increase the surface finish of the wire rod.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for the purpose of explanation and are not intended to limit the present invention.

Example 1

A carbon steel metal wire rod having a diameter of 1.45 mm and a carbon content of 0.82 wt% was drawn at a speed of 800 m / min using a wet multi-stage type drawing machine as shown in FIG. 2, with a diameter of 0.25 mm and a tensile strength of 320 Kg / mm ^2. The thin wire metal wires were prepared. Keep the slip rate S _n at 2% in the first half of 50% of the total exemption rate, and maintain the slip rate S _n at 4% in the middle of the fresh line up to 90% of the total exemption rate. In this case, the slip ratio S _n was maintained at 1.5%.

Example 2

A carbon steel metal wire rod having a diameter of 1.65 mm and a carbon content of 0.72 wt% was drawn at a speed of 600 m / min using a wet multistage draw type wire drawing machine as shown in FIG. 2 to obtain a diameter of 0.30 mm and a tensile strength of 280 Kg / mm ^2. The thin wire metal wires were prepared. Keep the slip rate S _n at 2% in the first half of 50% of the total exemption rate, and maintain the slip rate S _n at 4% in the middle of the fresh line up to 90% of the total exemption rate. In this case, the slip ratio S _n was maintained at 1.5%.

Comparative Example 1

A metal wire of carbon steel having a diameter of 1.45 mm and a carbon content of 0.82 wt% was drawn at a speed of 800 m / min using a drawing machine according to the conventional isotropic reduction die arrangement as shown in FIG. A thin wire metal wire having a tensile strength of 280 Kg / mm ² or more was prepared.

Comparative Example 2

A metal wire of carbon steel having a diameter of 1.65 mm and a carbon content of 0.72 wt% was drawn at a speed of 600 m / min using a drawing machine according to a conventional isotropic reduction die arrangement as shown in FIG. A thin wire metal wire having a tensile strength of 280 Kg / mm ² or more was prepared.

In Examples 1 and 2 and Comparative Examples 1 and 2, the disconnection rate, the salt value, the fatigue resistance, the die life, and the power consumption were measured, respectively, and the relative values when the value measured in Comparative Example 1 in Table 1 was 100 Represented by.

division Example 1 Comparative Example 1 Example 2 Comparative Example 2 Disconnection index 265 100 315 150 Salt index 165 100 185 150 Fatigue Index 120 100 105 90 Dice life index 235 100 285 120 Power Consumption Index 102 100 106 105

[Measurement of physical properties]

1) disconnection index

The number of wires cut during the production of 1 ton thin wire metal wire by the drawing process was evaluated as a relative index compared to Comparative Example 1.

2) salt index

When the gauge length is maintained at 100 times the wire diameter, the wire rod is rotated at a speed of 250 RPM in one direction after being bitten by a rotary chuck with one side fixed and the other with a reverse load of about 2% of the wire cutting strength. After measuring the number of revolutions until cutting was shown as a relative index relative to Comparative Example 1.

3) fatigue resistance index

Using the Reverse Bending Tester (manufactured by Bekaert), the tensile and compressive stresses were repeated under the stress condition of 90Kg / mm 2, and the cycle number until the cutting of the wire was measured. .

4) Dies life index

After producing 5 tons of thin wire metal wire by the drawing process, the used dies were collected, and the degree of expansion of each die diameter was measured in comparison with that of Comparative Example 1.

5) Power Consumption Index

After measuring the amount of power consumed during the production of 1 ton of metal wire by the drawing process, it is shown as a relative index compared to Comparative Example 1.

According to the present invention, a wire rod excellent in strength and fatigue resistance can be obtained while preventing disconnection at the time of drawing in a range in which the drawing speed is not lowered. In addition, the average life of the die can be extended to improve productivity.

Claims (1)

In the method of drawing a metal wire with a slip-type drawing machine so that the diameter of the filament is 0.10 to 0.40 mm, the die schedule is divided into the first half of the total reduction rate of 50%, the middle half of the total reduction rate of 90%, and the second half after the 90% reduction rate. S _n = {1- (1-r _{n + 1} ) / (1, where r _n is the actual reduction rate of the wire rod passing through the nth die, and R _n is the mechanical reduction rate in the capstan drawing the wire. The die slip ratio, expressed as -R _{n + 1} )} × 100, is set to 1 to 3% in the first half, 3 to 5% in the middle half and 1 to 2% in the second half, and two dies between the capstans in the second half. A method of drawing a high strength metal wire, wherein the reduction rate per die is adjusted to 5 to 8%.