KR20170102092A

KR20170102092A - Hybrid apparatus and method for wire drawing

Info

Publication number: KR20170102092A
Application number: KR1020160024093A
Authority: KR
Inventors: 이영석; 조동혁
Original assignee: 중앙대학교 산학협력단
Priority date: 2016-02-29
Filing date: 2016-02-29
Publication date: 2017-09-07
Also published as: KR101808574B1

Abstract

The present invention relates to a hybrid apparatus and method for drawing a wire rod. The present invention relates to a hybrid device for drawing a wire drawn out by a pulling force in one direction, comprising: a plurality of dies drawn while passing through the wire and decreasing in diameter as being arranged from a front end to a rear end; And a pair of coaxial rolling rolls rotatably disposed between the dies, and pressing both sides of the wire passed through the die to push the wire rod forward.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a hybrid apparatus and method,

The present invention relates to a hybrid apparatus and method for drawing a wire rod, and more particularly, to a hybrid apparatus and a wire rod method capable of eliminating the occurrence of disconnection or delamination of a wire rod by removing a backward tension applied to the wire rod by inserting a coin- The present invention relates to a hybrid apparatus and method for drawing a wire rod.

The ordinary wire drawing process is a process for producing a wire rod (diameter: 5.5mm) produced by a steel wire rope factory by continuously passing a die through a tensile force to produce a product having a diameter (0.5mm to 0.2mm) .

In the drawing process, the circular cross-section material (wire material) is continuously subjected to the drawing process, and the cross-sectional area is gradually decreased and the material strength is increased. The production of steel cords for automobile tires, which is a typical drawing material, is generally conducted through three drawing processes (primary: dry, secondary: dry, and tertiary: wet). Approximately 10 to 12 dies are sequentially arranged in each order, and the material is drawn through each die.

1 is a view showing a general drawing process. Fig. 1 shows a 4-pass drawing process as a drawing process for producing a common drawing material. The wire material 5 passes through the first die 1, the second die 2, the third die 3 and the fourth die 4 while the material cross-sectional area is reduced while the strength of the material is increased .

Fig. 2 is a view for explaining the cause of breakage of a material in a general drawing process. Fig. FIG. 2 shows the actual cross-section of the material in the process of drawing and disconnection when tri-axial tensile stress occurs in the material due to plastic deformation inside the drawing die. When triaxial tensile stress occurs, the reason for the disconnection is that due to the triaxial tensile stress, pores are generated, grown and coalesced between the nonmetallic inclusions and the matrix in the material, resulting in macroscopic size It grows as a crack.

Therefore, many efforts are made to suppress as much as possible nonmetallic inclusions from the fine steelmaking process during the drawing process. Until recently, the presence of nonmetallic impurities in wire rod products has been minimized, but the disconnection and delamination of the material still occur due to the limitation of the existing drawing process (generation of triaxial tensile stress).

FIG. 3 is a view showing generation of a triaxial tensile stress in a material in a general drawing process. FIG. Fig. 3 shows the result of predicting the 3-axis tensile stress generated in the material inside the die using a finite element method when a wire rod having a diameter of 5.5 mm enters the 4-pass drawing process and a 4 mm diameter drawing material is discharged. . As the number of passes increases, the back tension of the material increases, which increases the generation of tensile stress in the material. It can be seen that the three-direction stress in the 1,2,3-direction stress of the material in the die, that is, the pulling direction stress is the largest and the three-axis tensile stress is dominant, and the shear stress is hardly generated.

Therefore, the triaxial tensile stress is a direct cause of disconnection of the material or occurrence of delamination. On the other hand, in order to suppress the occurrence of disconnection or delamination of the material in the drawing process, the material is subjected to a heat treatment process in the middle of the drawing process to increase the ductility of the material, thereby suppressing the occurrence of disconnection or delamination.

However, since the heat treatment of the material added several times in the drawing process causes an increase in the production cost, the field is trying to reduce the reduction ratio of each pass. However, the reduction of the reduction rate leads directly to an increase in the number of passes, which causes a problem of increasing the production cost.

The parameters affecting the occurrence of internal defects in a general drawing process were investigated in order to eliminate the disconnection of the material frequently occurring in the general drawing process or the interlayer separation between the materials. Five typical factors are as follows. i) the smaller the section reduction rate, ii) the larger the semi-angle, iii) the higher the friction coefficient, iv) the lower the work hardening, v) the greater the back tension, Is increased.

Here, the rear tension is a resistance that occurs when the material is inserted into the die, that is, when it is pulled out, which has a great influence on the generation of tensile stress when the material inside the die undergoes plastic deformation. Of the five factors above, i), ii) and iii) are easily adjustable at any time and are properly controlled at the actual work site. Iv) also reduces the work hardening of the material by adding several heat treatment processes in the middle of the die and die at the actual work site. However, there is no practical way to solve v).

Korean Patent Publication No. 10-2007-0117948 (published on December 13, 2007)

The present invention relates to a method and apparatus for cutting a wire rod by removing a backward tension applied to the wire rod by inserting a rolling process during a drawing process during a wire drawing process to eliminate the occurrence of disconnection or delamination, And to provide a hybrid device and a method for drawing a wire rod which is reduced in size.

According to one embodiment of the present invention, a hybrid device for drawing a wire rod according to the present invention is a hybrid device for drawing a wire rod drawn out by a pulling force in one direction, wherein the wire rod is pulled out while passing through the wire rod, A plurality of dies whose diameters decrease; And a pair of coaxial rolling rolls rotatably disposed between the dies, and pressing both sides of the wire passed through the die to push the wire rod forward.

The diameter of the roll may be 5 to 50 times the diameter of the wire.

Wherein the rolls are elliptical rolls having an elliptical cross section through which the wire passes; And a circular coin roll having a circular cross section through which the wire rod passes.

The elliptically shaped rolling roll may be disposed at an upstream side of the circularly-shaped rolling roll, and the wire may be rolled while passing through the elliptically shaped rolling roll and then passing through the circularly-shaped rolling roll.

The elliptical cross section formed by the elliptical cone rolling roll can be designed to satisfy the following equation.

[Equation 1]

H = (1-R) * D1 * 0.9

W = (1-R) * D1 * 1.15

(Where H is the height of the elliptical cross section, R is the average cross-section reduction ratio, D1 is the diameter of the wire after one-pass drawing, and W is the width of the elliptical cross section.

The speed of the elliptically shaped rolling roll relative to the speed of the wire rod may be designed to be the same as the speed of the circular-shaped rolling roll relative to the speed of the wire rod.

The friction coefficient mu of the above-mentioned rolls of the present invention is 0.125 or less, and the rolling speed? Of the rolling rolls relative to the wire speed may be 1.225 or more.

The coefficient of friction μ of the above-mentioned rolls is 0.075 or more and 0.125 or less, and the rolling speed of the rolls relative to the wire speed is 1.075 or more and 1.225 or less.

According to another embodiment of the present invention, there is provided a hybrid method for drawing a wire rod according to the present invention, wherein a plurality of dies are passed through a plurality of dies A pulling step of; And a coin-rolling step of pressing both sides of the wire rod to push the wire rod forward, while passing through a pair of coin-like rolling rolls disposed between the dies.

Wherein the rolling step includes an elliptical rolling step in which the wire rod passes through an elliptical cross section; And a circular coin-rolling step in which a cross-section through which the wire rod passes is circular.

The elliptical cross section formed in the elliptical rolling step may be designed to satisfy the following equation.

[Equation 1]

H = (1-R) * D1 * 0.9

W = (1-R) * D1 * 1.15

According to the embodiment of the present invention, it is possible to eliminate the disconnection or the occurrence of delamination of the wire by removing the backward tension applied to the wire by inserting a rolling process during the drawing process in the wire drawing process.

1 shows a general drawing process.
Fig. 2 is a view for explaining the cause of a material break in a general drawing process; Fig.
Fig. 3 is a view showing generation of triaxial tensile stress in a material in a general drawing process. Fig.
FIG. 4 illustrates a hybrid device according to an embodiment of the present invention. FIG.
5 is a graph comparing the magnitudes of triaxial tensile stresses in a general drawing process and a drawing process according to an embodiment of the present invention.
6 is a cross-sectional view of a component in accordance with a drawing process of a wire rod.
7 is a view showing a wire rod section in an elliptical rolling roll.
8 is a view showing a section of a wire rod in a circular-form rolling roll.
Fig. 9 is a view showing the speed of the wire rod and the coin roll. Fig.
10 is a view showing the relationship between the coefficient of friction of a roll of a coin roll and the roll speed of a coin roll relative to a wire speed.
11 and 12 are views showing a recommended operation area of the drawing process.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, an embodiment of a hybrid apparatus and method for drawing a wire according to the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to like elements, And redundant explanations thereof will be omitted.

FIG. 4 is a view showing a hybrid device according to an embodiment of the present invention. FIG. 5 is a diagram comparing magnitudes of triaxial tensile stresses in a general drawing process and a drawing process according to an embodiment of the present invention.

As shown, the hybrid device according to the present invention is a hybrid device for drawing a wire drawn out by a pulling force in one direction. The hybrid device according to the present invention is drawn out while passing through the wire rod 50. When the wire rod 50 is arranged from the front end to the rear end, A plurality of dies (10, 20); And a pair of rotatably arranged dies 10 and 20 between which a wire rod 50 passing through the die 10 and 20 is pressed to press both sides of the wire rod 50 forward, Rolls 30,40.

A plurality of the dies 10 and 20 may be arranged apart from each other by a predetermined distance as shown in Fig. Although two dies 10 and 20 are shown in FIG. 4, three or more dies 10 and 20 may be disposed depending on the diameter of the finally drawn wire. The wire rods 50 pass through the dies 10 and 20 arranged in this manner while being pulled out by the pulling force, and the diameters are reduced according to the reduction ratio each time the dies 10 and 20 pass through the dies 10 and 20. For reference, the dies 10,20 include a first die 10 and a second die 20, which is smaller in diameter than the first die 20 and disposed at a later stage.

Meanwhile, in the present embodiment, the diameter of the rolls 30, 40 is 5 to 50 times the diameter of the wire 50, have. This is because the contact angle between the wire rod 50 and the rolls 30 and 40 becomes large when the diameter of the ball rolling rolls 30 and 40 is smaller than 5 times the diameter of the wire rod 50, If the diameter of the ball rolling rolls 30 and 40 is larger than 50 times the diameter of the wire rod 50, there is a problem that the torque required for rotating the ball rolling rolls 30 and 40 becomes large, This can happen.

Next, the ball rolling rolls 30 and 40 are an elliptical rolling roll 30 having an elliptical cross section through which the wire rod 50 passes; And a circular cone rolling roll 40 having a circular cross section through which the wire rod 50 passes. For reference, the grooves formed on the surface of the elliptical rolling roll 30 indicate the elliptical grooves 32, and the grooves formed on the surface of the circularly-shaped rolling roll 40 indicate the circular grooves 42.

In the present embodiment, the reason why the cast rolling process is arranged during the drawing process performed in the dies 10 and 20 is as follows. The rolling process of the rolls allows a spreading in the axial direction of the roll when the material is plastic-deformed between the rolls, so that the triaxial tensile stress is not generated inside the material. Also, by properly adjusting the speed of the roll, it is possible to eliminate the back tension which always occurs in the material drawn from the die disposed after the rolling process. If the power source for driving the roll is present, the wire drawing process is performed while the wire rod is drawn out to one side by the pulling force provided by the power source. Then, the speed of the roll should be synchronized with the material pulling speed at each die, and the material speed at each die can be easily obtained under the condition that the mass flow rate is constant.

Referring to FIG. 5, finite element simulation of the size of triaxial tensile stress in a general drawing process and a drawing process according to an embodiment of the present invention is shown.

The diameter of the initial wire rod 5 is 5.5 mm, and the diameter of the wire rod 5 drawn through the four passes is 4.0 mm. The reduction rate of each pass is 15% (diameter vs. inlet diameter). The results of the finite element analysis show that the triaxial tensile stress is generated in the material passing through the 2,3,4 pass in the general drawing process. That is, it can be seen that the magnitude of the triaxial tensile stress continuously increases due to the influence of the rear tension applied to the wire rods 5.

On the other hand, in the drawing process according to an embodiment of the present invention, the back-tension applied to the wire rod 50 is removed from the rolling process of the coin rolling disposed between the drawing process, so that no tensile stress is generated in the wire rod 50 can see. Accordingly, the triaxial tensile stress can be prevented from being generated in the wire rod 50 by the rolling process shown in this embodiment, thereby preventing disconnection or delamination. It is possible to eliminate the possibility of disconnection or delamination of the wire member 50 even if a general level steelmaking process (posting) is performed when the wire member 50 is produced.

6 is a cross-sectional view showing a component in accordance with the drawing process of the wire rod. The diameter of the wire 50 passing through the first die 10 is D2, the diameter after passing through the rolling rolls 30 and 40 is D3, 2 Diameter of the wire rod 50 passed through the die 20 is defined as D4. The height of the wire rods 50 passing through the elliptical rolling roll 30 is defined as H and the width thereof as W. [

The cross section of the wire rods 50 passed through the elliptical roll-forming roll 30 is well shown in Fig. Referring to this, the cross-sectional shape formed by the pair of elliptical rolls 30 is flat oval. Therefore, the wire rods 50 having passed through the elliptical rolling roll 30 have a cross-sectional shape having a small height and a large width as shown in Fig.

Next, the cross section of the wire rod 50 passed through the circular-arc rolling roll 40 is well shown in Fig. Referring to this, the cross-sectional shape formed by the pair of the circular-ball rolling rolls 40 is circular. Therefore, the wire rod 50 having passed through the circular ball rolling roll 40 has a sectional shape in which the height becomes larger and the width becomes smaller as shown in Fig.

Based on the coefficients defined above, the equation for the preferred design of the elliptical rolling roll 30 is as follows.

[Equation 1]

H = (1-R) * D1 * 0.9

W = (1-R) * D1 * 1.15

If the cross section of the elliptical roll 30 is within the range of 5 to 25% of the average cross-sectional reduction ratio R, the wire 50 may not be well engaged with the roll during the rolling process, It is possible to prevent the problem that the torque is increased and the machining efficiency is lowered.

Fig. 9 is a graph showing the speeds of the wire rod and the coin type rolling roll. Referring to this, the absolute surface speed of the rolls 30 and 40 is not important when determining the proper speed of the rolls 30 and 40, and the surface speed of the rolls is important. Where V1 is the velocity of the wire 50 passing through the second die 20, V2 is the velocity of the wire 50 passing through the circular ball rolling roll 40, V3 is the radius of the elliptical rolling roll 30 V4 is the velocity of the wire rod 50 passing through the first die 10, V5 is the velocity of the initial wire rod 50, U1 is the rotational speed of the circular ball rolling roll 40, And U2 is the rotational speed of the elliptical rolling roll 30.

In this case, U2 / V3 and U1 / V2 can be defined as the rolling speed of the rolling rolls relative to the wire speed, respectively. If U2 / V3 = U1 / V2 is satisfied, stable operation is possible.

Fig. 10 is a graph showing the relationship between the friction coefficient of the coiling roll and the coiling roll speed versus wire speed. Referring to this figure, the figure shows the three-axis stress of the wire according to the friction coefficient and the wire speed versus the roll speed, based on the experimental design (DOE).

10, it is determined that the maximum triaxial stress is positive (+) and the possibility of internal defect in the wire 50 is determined. If the maximum triaxial stress is compressive stress (-) and the internal defect of the wire 50 is It is judged to be offset. Therefore, it can be said that there is no possibility of delamination during operation in the region where the maximum triaxial stress is compressive stress.

For reference, the coefficient of friction of the roll of the coin roll is μ, and the roll speed of the coin rolling compared to the speed of the wire is expressed as γ (U2 / V3, U1 / V2).

11 and 12 are views showing a recommendation area for fishing in the drawing process. Referring first to Fig. 11, it is preferable that the recommended work area is a friction coefficient mu of not more than 0.125. If the coefficient of friction exceeds 0.125, the quality of the surface of the wire rod 50 is deteriorated. In addition, it is preferable that the coiling rolling roll speed y to the wire material speed is 1.225 or more. If the rolling speed of the casting rolls is higher than 1.225, there is a problem that the reduction rate per pass decreases.

The recommended operation area shown in Fig. 11 shows a more reliable area than the recommended operation area shown in Fig. 12, but there is a need for the operator to directly calculate the control area.

Next, referring to FIG. 12, it is preferable that the recommended operating range of the friction coefficient μ is not less than 0.075 and not more than 0.125, and the rolling speed γ of the rolling roll relative to the wire speed is not less than 1.075 and not more than 1.225. If the coefficient of friction exceeds 0.125, the quality of the surface of the wire rod 50 is lowered. If the coefficient of friction is less than 0.075, the triaxial tensile stress is generated because the rolls 30 and 40 can not push the wire rod 50 sufficiently. . Also, it is preferable that the value of the coiling roll speed gamma is 1.075 or more and 1.225 or less relative to the wire material speed. If the roll speed is higher than 1.225, the reduction rate per pass decreases. If the roll speed is lower than 1.075, a tensile force is generated in the opposite direction of the wire 50, thereby generating a triaxial tensile stress.

The recommended operation area shown in FIG. 12 is relatively narrow and has a portion where the triaxial stress slightly exceeds 0, but there is an advantage that the operator can easily determine the operation area.

4, only the die rolls 30 and 40 are disposed between the two dies 10 and 20, but a plurality of dies may be provided, and the die rolls 30 and 40 may be interposed therebetween. , 40 may be disposed to perform the rolling process. That is, a drawing process such as drawing -> elliptical rolling -> circular forming rolling -> drawing -> elliptical forming rolling -> circular forming rolling -> drawing can be repeatedly performed.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as set forth in the following claims It will be understood that the invention may be modified and varied without departing from the scope of the invention.

1: first die 2: second die
3: Third die 4: Fourth die
5: wire rod
10: first die 20: second die
30: elliptical rolling roll 32: oval groove
40: circular-shaped rolling roll 42: circular groove
50: wire rod

Claims

1. A hybrid device for drawing a wire drawn out by a pulling force in one direction,
A plurality of dies that are pulled out while passing through the wire rods and whose diameters decrease as they are arranged from the front end to the rear end; And
And a pair of coaxial rolling rolls rotatably disposed between the dies and pressing both sides of the wire passed through the die to push the wire rod forward.

The method according to claim 1,
Wherein the diameter of the roll is 5 to 50 times the diameter of the wire.

The method according to claim 1,
The above-
An elliptical coin roll having an elliptical cross section through which the wire passes; And
And a circular-shaped rolling roll having a circular cross-section through which the wire rod passes.

The method of claim 3,
Wherein the elliptical shaped rolling roll is disposed at an upstream side of the circularly-shaped rolling roll, and the wire rod is passed through the elliptical rolling roll, and then rolled while passing through the circularly-shaped rolling roll.

The method of claim 3,
Wherein the elliptical cross section formed by the elliptical shaped rolling roll is designed to satisfy the following expression.
[Equation 1]
H = (1-R) * D1 * 0.9
W = (1-R) * D1 * 1.15
(Where H is the height of the elliptical cross section, R is the average section reduction ratio, D1 is the diameter of the wire after the one-pass drawing, and W is the width of the elliptical cross section.

The method of claim 3,
Wherein the speed of the elliptical shaped rolling roll relative to the speed of the wire rod is designed to be the same as the speed of the circular-shaped rolling roll relative to the speed of the wire rod.

7. The method according to any one of claims 1 to 6,
Wherein the coefficient of friction mu of the roll is 0.125 or less and the ratio of the rolling speed of the roll to the wire speed is 1.225 or more.

8. The method of claim 7,
Wherein the friction coefficient 占 of the above-mentioned rolls is 0.075 or more and 0.125 or less, and the ratio of the rolling speed? To the wire speed is 1.075 or more and 1.225 or less.

A hybrid method for drawing a wire drawn out by a pulling force in one direction,
A plurality of drawing steps in which a plurality of dies are reduced in diameter while the wire rod passes; And
And a step of pressurizing both sides of the wire while passing through a pair of coin rolls disposed between the dies to push the wire forward.

10. The method of claim 9,
The method of any of the preceding claims,
An elliptical rolling step in which the wire rod passes through an elliptical cross section; And
And a circular-shaped rolling step in which a cross-section through which the wire rod passes is circular.

11. The method of claim 10,
Wherein the elliptical cross section formed in the elliptical rolling step is designed to satisfy the following equation.
[Equation 1]
H = (1-R) * D1 * 0.9
W = (1-R) * D1 * 1.15
(Where H is the height of the elliptical cross section, R is the average section reduction ratio, D1 is the diameter of the wire after the one-pass drawing, and W is the width of the elliptical cross section.

12. The method according to any one of claims 9 to 11,
Wherein the friction coefficient 占 of the above-mentioned rolls is 0.125 or less, and the rolling speed? Of the rolling rolls relative to the wire speed is 1.225 or more.

13. The method of claim 12,
Wherein the friction coefficient 占 of the above-mentioned rolls is 0.075 or more and 0.125 or less, and the rolling speed? Of the rolling rolls relative to the wire speed is 1.075 or more and 1.225 or less.