KR20200036551A - dummy and casting method using the same - Google Patents

Abstract

The present invention relates to a dummy bar, which draws a cast piece from a cast and moves the cast piece in a casting direction, and comprises: a head unit which is inserted into the cast and allows a portion thereof to move in a thickness direction of the cast piece to compress by a reduction force applied from the outside; and a body unit extended from the head unit. Therefore, according to embodiments of the present invention, an upper reduction roll is lowered to start a soft reduction operation when the head unit of the dummy bar enters a soft reduction zone. An initial cast piece unit connected to the head unit can be sufficiently and softly reduced to suppress or prevent center segregation and gas pockets. Accordingly, the quality of the initial cast piece unit can be improved in comparison to a conventional technique. Also, the length of the initial cast piece unit to be cut can be reduced.

Description

Dummy bar and casting method using the same

The present invention relates to a dummy bar and a casting method using the same, and more particularly, to a dummy bar capable of preventing quality degradation and a casting method using the same.

The casting facility is a facility that receives refined molten steel from a steelmaking facility and casts it into cast pieces of various shapes. Such a casting facility receives molded molten steel from a tundish and solidifies it into a cast shape, secondarily cools a cast drawing continuously from the mold, and inserts into the mold before starting casting and a cooling stand performing a series of molding operations. It includes a dummy bar that is drawn to the lower side of the mold and moves along the cooling table while the initial casting part solidified at the beginning of casting is connected when the casting is started to close the lower opening of the mold.

On the other hand, while the cast steel is solidified and cooled while passing through the cooling zone, the concentrated molten steel remains in the center of the cast steel to form a central segregation, and the molten steel is solidified into a solidified solidification shell and the volume changes to form pores. . Segregation and pores in the center of the cast steel thus formed are the main defect factors that degrade the internal quality of the cast steel.

Therefore, at the end of solidification of the cast piece, the cast piece is softly reduced in the thickness direction to remove the central segregation and pores of the cast piece. A plurality of pressing rolls arranged in one direction so as to face the upper surface of the casting at the end of solidification of the casting to descend is lowered toward the casting, and the casting is pressed in the thickness direction. At this time, the cast steel is pressed by the solidification shrinkage rate at the end of solidification, and the flow of concentrated molten steel existing between the columnar tablets due to the solidification shrinkage is suppressed to flow into the center of the cast, and the residual voids are compressed to suppress the occurrence of central segregation of the cast. .

On the other hand, in the prior art, when the head of the dummy bar connected to the initial cast part completely out of the light-pressing section where the rolling-down roll was installed, the rolling-down roll was lowered to have a desired pressing force. This is because, when the head portion is in the light-pressing section, when the roll-down roll is lowered, the pressing force applied to the head portion is applied back to the roll-down roll or casting equipment, causing a failure or load, which may cause a safety accident.

However, in this case, since the pressure drop of the initial cast part connected to the head part is achieved only when the end or the end point of the light pressure section is reached, the pressure drop for the initial cast part is not sufficient. In this case, deterioration in quality occurs due to central segregation and pores in the initial cast part. In addition, the length of the initial cast part having poor quality becomes long, which causes a problem of cutting a large amount of the initial cast part.

Korean Registered Patent KR1252647

The present invention provides a dummy bar capable of sufficiently performing the initial pressure under the casting part and a casting method using the same.

The present invention provides a dummy bar and a casting method using the same, which can improve the quality of the initial cast part that is cast in contact with and connected to the dummy bar head.

The present invention is a dummy bar for drawing a cast from a mold and moving the cast in the casting direction, which can be inserted into the mold and partially moved in the thickness direction of the cast by the pressing force applied from the outside to compress Possible head portion; And a body portion formed extending from the head portion.

The head portion is arranged in the thickness direction of the cast, and includes a first body and a second body interconnected, and the first body is in the direction of the second body by a force applied from the outside of the first body. It is possible to move.

At least a portion of the first body is accommodated in the second body, and a movement space in which a direction in which the first body is located is opened is provided.

At least a part of the first body can be inserted into the moving space.

It is installed to penetrate the side wall of the second body surrounding the moving space, the end inserted into the second body is connected to the first body, and includes a movable portion movable with the first body.

The side wall of the second body is provided with a moving groove formed in an outer to inner direction of the side wall so that the moving part can penetrate, and the moving groove is formed to extend in the moving direction of the first body on the side wall.

The moving part is provided to penetrate the moving groove of the second body, the end inserted into the second body is a moving member connected to the first body; And a fastening member which is located inside the second body and is installed so that the moving member penetrates therethrough, and is capable of adjusting adhesion to the inner surface of the second body.

The moving part is installed to penetrate the moving groove of the second body, the end inserted into the second body includes a moving member connected to the first body, and the moving groove is located below the moving member. It is installed inside and includes an elastic member having elastic force.

It is installed to connect between the first body and the second body in the interior of the second body, and includes an elastic member capable of stretching and contracting with movement of the first body.

The casting method according to the present invention comprises: drawing a head portion of a dummy bar from a mold and a cast piece connected to the head portion; A step of continuously moving the dummy bar from the lower side of the mold to solidify the cast steel drawn from the mold; And a step of lowering the cast piece that has entered the lower pressure section provided on the lower side of the mold. In the process of lowering the cast piece, when the head portion enters the lower pressure section, the plurality of upper rolling rolls The process includes lowering the upper pressing roll positioned at the upper side of the head portion and the upper pressing roll positioned at the rear of the head portion in the light pressing section.

In descending the upper pressing roll positioned corresponding to the upper side of the head portion and the upper pressing roll located behind the head portion in the lower pressure section, only the head portion entered into the lower pressure section is lowered or lowered. The head part entered into the section and the cast piece located at the rear of the head part entering into the light-pressing section are pressed together.

The light-pressing section, from the point where the first upper rolling roll is located, to the point where the last upper rolling roll is located, among the plurality of upper rolling rolls, the position of the first upper rolling roll is the starting point of light rolling, And when the rear end of the head portion connected to the cast piece reaches the starting point under the light pressure, lowering the upper pressing roll positioned corresponding to the upper side of the head portion.

The light-pressing section, from the point where the first upper rolling roll is located, to the point where the last upper rolling roll is located, among the plurality of upper rolling rolls, the position of the first upper rolling roll is the starting point of light rolling, When the position of the last upper pressing roll is the end point under the light pressure, and the rear end of the head portion is located between the start point under the light pressure and the end point under the light pressure past the start point under the light pressure, the position corresponding to the upper side of the head And lowering the upper rolling roll.

The head portion passes through the light-pressing section, and the upper roll-down roll positioned at the rear of the head portion at the present time maintains the lowered state from the previous time.

In the lowering of the upper rolling roll positioned corresponding to the upper side of the head portion, by pressing the pressing force applied from the upper rolling roll, a part of the head portion is moved in the thickness direction of the cast and compressed.

The head portion is provided with a first body that is movable by a pressing force applied from the upper pressing roll and a moving space in which at least a portion of the first body can be accommodated, and a direction in which the first body is located is opened. It includes a second body, and by the pressing force applied from the upper pressing roll, the first body is compressed to reduce the moving space of the second body.

Before starting the casting, the process of fastening the moving part so that the end is connected to the first body through the side wall of the second body surrounding the moving space; And adjusting the adhesion between the moving part and the second body to adjust the movement resistance of the first body.

And after the casting is finished, returning the first body, which has been moved in the second body direction by the pressing force applied from the upper pressing roll, to a state before pressing.

According to the embodiments of the present invention, when the head portion of the dummy bar enters the lower pressure section, the upper pressing roll is lowered to start the lower pressure operation. Accordingly, the initial cast portion connected to the head portion can be sufficiently reduced to suppress or prevent the occurrence of central segregation and pores. For this reason, the quality of the initial cast part can be improved compared to the conventional one. In addition, there is an effect that can reduce the length of the initial cast portion to be cut.

1 is a view showing a casting equipment according to an embodiment of the present invention
2 is a view showing a dummy bar according to an embodiment of the present invention
Figure 3 is a three-dimensional view showing the head portion of the dummy bar according to an embodiment of the present invention and a cast piece connected thereto
Figure 4 is a three-dimensional view showing the head portion of the dummy bar according to an embodiment of the present invention
FIG. 5 (a) is a view taken along line A-A 'of FIG. 4 (a), and shows a state before the first body of the head part descends.
FIG. 5 (b) is a view taken along line A-A 'of FIG. 4 (b), showing a state in which the first body of the head portion is lowered.
FIG. 6 (a) is a view taken along line B-B 'of FIG. 4 (a), and shows a state before the first body of the head part descends.
FIG. 6 (b) is a view taken along line B-B 'of FIG. 4 (b), showing a state in which the first body of the head portion is lowered.
7 is a view showing a head portion according to a first modification of the embodiment
8 is a view showing a head portion according to a second modification of the embodiment
9 (a) to 9 (d) are views for explaining the operation of the lower pressure in accordance with the movement of the head portion of the dummy bar according to an embodiment of the present invention
10 (a) to 10 (d) are views for explaining the operation of the lower pressure according to the third modification of the embodiment
Figure 11 (a) to Figure 11 (b) is a view for explaining the operation of the conventional lower pressure

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and the scope of the invention to those skilled in the art is completely It is provided to inform you. The same reference numerals in the drawings refer to the same elements.

The present invention relates to a dummy bar that can prevent the quality of the cast piece and a casting method using the same. In addition, the present invention relates to a dummy bar capable of improving the quality of an initial cast part that is cast in contact with or connected to a dummy bar head and a casting method using the same.

1 is a view showing a casting equipment according to an embodiment of the present invention. 2 is a view showing a dummy bar according to an embodiment of the present invention. 3 is a three-dimensional view showing a head portion of a dummy bar and a cast piece connected thereto according to an embodiment of the present invention.

4 is a three-dimensional view showing a head portion of a dummy bar according to an embodiment of the present invention. Here, FIG. 4 (a) is a state before the first body of the head part descends, and FIG. 4 (b) shows a state in which the first body is lowered.

FIG. 5 (a) is a view taken along line A-A 'of FIG. 4 (a), and shows the state before the first body of the head portion descends. FIG. 5 (b) is a view taken along line A-A 'of FIG. 4 (b), and shows a state in which the first body of the head portion is lowered. FIG. 6 (a) is a view taken along line B-B 'of FIG. 4 (a), and shows the state before the first body of the head portion descends. FIG. 6 (b) is a view taken along line B-B 'of FIG. 4 (b), showing a state in which the first body of the head portion is lowered.

Hereinafter, a casting facility according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6.

Referring to FIG. 1, the casting facility receives the molten steel and temporarily stores it in a tundish (10) for storing and temporarily storing the molten steel, and receives the molten steel stored in the tundish (10) in an open form to initially solidify in a predetermined shape ( A primary solidification) mold (20), a plurality of rolls (5110, 5210) arranged and arranged in the casting direction from the lower side of the mold (20) to move or guide the drawn cast (S) in one direction ), The cooling unit (5000) for secondary solidification while moving the cast (S), is inserted to close the lower opening of the mold (20) before casting starts, and when casting starts, the cast (S) solidified at the beginning of casting It includes a dummy bar 6000 that is drawn downward from the mold 20 in a connected state and moves along the cooling table 5000.

In addition, the casting equipment includes a position detecting unit 4000 capable of detecting the position of the dummy bar 6000 in real time during casting. In addition, the casting equipment is located in front of the immersion nozzle 30, the cooling table 5000 for supplying the molten steel of the tundish 10 to the mold 20, a cutting machine (not shown) for cutting the finished solidified piece Includes.

Hereinafter, a cast region solidified on the dummy bar 6000 or in contact with the dummy bar 6000 is referred to as an initial cast portion.

The tundish 10 is a means for supplying molten steel to the mold 20, and is a shape of a container having an inner space for receiving molten steel, and the outermost outer wall is formed of iron shell, and the inner wall of the iron shell is protected by refractory material.

The immersion nozzle 30 is used to supply the molten steel of the tundish 10 to the mold 20, and is installed to connect between the tundish 10 and the mold 20.

The mold 20 has a hollow shape having upper and lower sides open and an internal space. In addition, the mold 20 is in the form that the lower side is open as described above for the continuous drawing of the primary solidified casting S therein, and the lower opening is closed by the dummy bar 6000 before casting starts. . That is, before injecting molten steel into the mold 20, the dummy bar 6000 is inserted through the upper opening of the mold 20 to close or seal the lower opening of the mold 20 with the dummy bar 6000, Thereafter, molten steel is injected into the mold 20.

Cooling table 5000 is provided with a plurality of rolls (hereinafter, guide rolls 5110) arranged in one direction from the lower side of the mold 20, the casting (S) drawn from the mold 20 in one direction While providing a driving force to move, a plurality of rolls (hereinafter referred to as rolling-down rolls 5210) arranged in one direction from the front of the guide section 5100 and the guide section 5100 to guide the movement, to press down the cast piece S )) Includes a lower pressure (5200).

The guide portion 5100 is located between the plurality of guide rolls 5110 and a plurality of guide rolls 5110 arranged from the lower side of the mold 20 to the front end of the lower pressure portion 5200 and toward the cast piece S It includes a nozzle (not shown) for spraying coolant.

The guide roll 5110 is installed to face the upper and lower surfaces of the cast piece S, respectively. Hereinafter, the guide roll arranged to face the upper surface of the cast piece S is referred to as an upper guide roll 5111a and a guide roll arranged to face the lower surface of the cast piece S is called a lower guide roll 5111b.

Then, a nozzle is provided between the plurality of upper guide rolls 5111a and the plurality of lower guide rolls 5111b to spray cooling water toward the cast piece S.

On the other hand, the cast piece S drawn from the mold 20 moves to pass between the plurality of upper guide rolls 5111a and lower guide rolls 5111b, and is solidified by the injected cooling water.

By the way, while the slab S is solidified and cooled while passing through the cooling table 5000, unsolidified molten steel may remain in the center portion in the thickness direction of the slab S, which is a factor for generating central segregation. In order to prevent this, at the end of solidification of the cast steel S, the cast steel S is lightly reduced in the thickness direction. To this end, a light pressure lower portion 5200 is installed in the end of solidification of the cooling table 5000.

Hereinafter, a position in which the lower pressure section SRS or the lower pressure section 5200 is installed will be described.

As the casting (S) is solidified and cooled while passing through the cooling table 5000, the amount of liquid in the center of the casting (S) decreases from the lower side of the mold (20) toward the direction in which the cutter (not shown) is located. , Solid phase increases. That is, the solid phase rate increases from the lower side of the mold 20 toward the direction in which the cutter is located.

Accordingly, according to the solid phase rate of the center of the cast, the cooling table 5000 can be divided into a plurality of sections. For example, the cooling table 5000 may be divided into an initial solidification period, a mid-solidification period, and a late-solidification period in the extending direction from the lower side of the mold 20 according to the solid phase rate of the cast iron.

When the solidification rate of the solidification of the cast piece S is complete without the liquid phase in the cooling zone 5000, that is, when the solidification rate of the solidification completion point is '1.0', for example, a section where the solidification rate is 0.3 or more is referred to as a final solidification period. .

The lower part of the pressure 5200 may be installed in a section having a solid phase rate of 0.3 or more, for example, in a section having a solid phase rate of 0.3 to 1.0, or in a section of 0.3 to 0.7, or in a section of 0.6 to 0.9. have. During the end of solidification, the position where the lower pressure 5200 is installed may be variously adjusted according to the steel type to be cast and the specifications of the casting equipment.

The end of solidification of the cooling zone 5000 is a value set in advance by the specifications of the casting equipment, the amount of cooling water injection, the casting speed, and the like. In addition, during the end of solidification, the position at which the lower pressure 5200 is installed is determined according to the steel type to be cast.

The lower pressure part 5200 includes a driving part 5220 located in front of the guide roll 5110 and providing a driving force for raising and lowering the pressing roll 5210 and a pressing roll 5210 for lowering the cast steel.

The rolling roll 5210 is a plurality of upper rolling rolls 5211a arranged in one direction so that each of them faces the upper surface of the cast piece S from the rear of the upper guide roll 5111a, each having a plurality of upper rolling rolls ( It is located below the upper rolling-down roll 5211a to face 5211a), and includes a plurality of lower rolling-down rolls 5211b arranged in an array direction of the plurality of upper rolling-down rolls 5211a.

Then, the driving unit 5220 is connected to a plurality of upper rolling rolls 5211a, and elevating and lowering the plurality of upper rolling rolls 5211a, thereby adjusting an interval between the upper rolling rolls 5211a and the lower rolling rolls 5211b. do.

Hereinafter, among the plurality of upper rolling rolls 5211a and the plurality of lower rolling rolls 5211b of the cooling table 5000, the first upper rolling roll 5211a and the first lower rolling roll 5221b are positioned from the last. The section up to the position of the upper rolling roll 5211a and the last lower rolling roll 5211b is referred to as a light rolling section SRS (see FIG. 9).

In addition, for convenience of explanation, reference numerals of the first upper rolling roll which is one of the plurality of upper rolling rolls 5211a are HR ₁ , and LR of the first lower rolling roll of the plurality of lower rolling rolls 5211b is LR. _It is described as ₁ .

However, the first upper rolling roll HR ₁ is one of the plurality of upper rolling rolls 5211a, and the first lower rolling roll LR ₁ is one of the plurality of upper rolling rolls 5211a.

In addition, the position where the first upper rolling-down roll HR ₁ and the first lower rolling-down roll LR _{1 of the} cooling zone 5000 are installed is referred to as a light-pressing starting point P ₁ , and the last of the cooling zone 5000 The installed positions of the upper rolling-down roll 5211a and the last lower rolling-down roll 5211b are named as the ending point P ₂ under light pressure (refer to FIG. 9).

The driving unit 5220 is connected such that a plurality of upper rolling-down rolls 5211a are driven individually or independently. The driving unit 5220 individually drives the plurality of upper rolling rolls 5211a according to the position of the head unit 6100 of the dummy bar 6000 and more specifically, the dummy bar detected from the position detection unit 4000.

The driving unit 5220 according to the embodiment is a hydraulic cylinder type, but is not limited thereto, and any means may be used as long as it is a means capable of elevating and lowering the upper pressing roll 5211a.

The lower pressure portion 5200 is a means for lowering the casting piece S to compensate for the solidification contraction at the end of solidification, and the pressing force applied to the casting piece S is the upper pressing roll 5211a and the lower pressing roll 5221b. It is determined by the spacing between the gaps, that is, the gaps. And, the gap between the upper rolling roll 5211a and the lower rolling roll 5211b is adjusted by the movement of the upper rolling roll 5211a.

At this time, the gap between the upper lower roll 5221a and the lower lower roll 5221b lowered for lowering the pressure is smaller than the gap between the upper guide roll 5111a and the lower guide roll 5111b. Then, in order to control the gap between the plurality of upper rolling rolls 5211a and the plurality of lower rolling rolls 5211b for the reduction of the pressure of the cast piece S, from the starting point (P ₁ ) under light pressure to the ending point (P) under light pressure It is desirable to adjust so that the gap decreases as it goes to ₂ ).

The dummy bar 6000 closes the lower opening of the mold 20 before casting starts, and after casting starts, the cast piece S is drawn in a connected state and moves along the cooling table 5000. That is, when the dummy bar 6000 closes the lower opening of the mold 20, molten steel is injected into the mold 20. At this time, the molten steel injected into the mold 20 at the beginning of casting is solidified to be connected to the dummy bar 6000 or to the dummy bar 6000. Then, after the dummy bar 6000 is drawn from the mold 20, it moves along the cooling table 5000, and the initial cast part is drawn and moved in contact with or connected to the dummy bar 6000.

Referring to FIG. 2, the dummy bar 6000 is inserted into the mold 20 to close the mold 20 before casting starts, and when passing through the light pressure section SRS, from the light pressure lower part 5200 It includes a head portion 6100 capable of contracting or compressing in the thickness direction of the cast piece S by a pressing force applied thereto and a body portion 6200 formed to extend in one direction from the head portion 6100.

Here, the body portion 6200 includes a main body 6210 formed from the front end 6100a of the head portion 6100 and a tail portion 6220 formed from the main body.

The head portion 6100, the main body 6210, and the tail portion 6220 may be connected in a link type so that they can freely flow in an interconnected state. And, the extension length of the head portion 6100 and the tail portion 6220 in the direction of movement of the dummy bar 6000 or the cast piece S may be 10% or less of the main body 6200.

The main body 6210 includes a plurality of blocks arranged in series in the casting direction. The plurality of blocks may be a pin-linked link structure to be individually flowable.

The tail part 6220 is a plate shape connected to the other end of the main body 6210, and a fastening groove 6300h capable of fastening a traction device (not shown) is provided.

The head part 6100 has a structure capable of contracting or compressing in the thickness direction of the cast piece S by the pressure applied from the lower pressure part 5200. More specifically, as illustrated in FIGS. 3 to 6, the head portion 6100 is moved by the pressing force applied from the upper pressing roll 5211a of the lower pressing portion 5200 when passing through the lower pressing section SRS. The first body 6110 movable in the direction of the lower pressing roll 5211b, the first body according to the pressing force applied to the second body 6120 and the first body 6110 separated from the first body 6110 The first body 6110 and the second body 6120 are connected so that the movement of the 6110 is possible, and the movement is possible along with the first body 6110 and applied from the lower pressure 5200 according to the combined state. It includes a moving unit 6130 to adjust the movement resistance of the first body 6110 according to the pressing force.

Here, since the first body 6110 moves in the direction of the lower surface of the lower rolling roll 5211b or the cast piece S by the pressing force applied from the upper rolling roll 5211a, for convenience of explanation, hereinafter 1 The body 6110 is moved to the lower surface of the lower rolling roll 5211b or the cast piece S by the pressing force applied from the upper rolling roll 5211a.

First, the second body 6120 will be described.

Referring to FIG. 5, the second body 6120 has an inner space in which the upper side is opened so that at least a portion of the first body 6110 can be inserted or lowered, and is recessed in a downward direction from the upper side. Here, the inner space provided in the second body 6120 is a space that is moved while the lower portion of the first body 6110 is inserted, hereinafter referred to as a moving space. In addition, hereinafter, among the walls surrounding the moving space of the second body 6120, the wall positioned below the moving space is referred to as a lower wall 6121, and a wall positioned in the lateral direction of the moving space is referred to as a side wall 6122. do.

Among the second bodies 6120, a side wall 6122 surrounding the moving space is provided with a groove (hereinafter referred to as a moving groove 6122h) that penetrates in the direction of the moving space from the outside and extends in the vertical direction. The moving groove 6122h is a groove in which the moving portion 6130 described later is installed.

The first body 6110 is located on the upper side of the second body 6120, and it is possible to move downward toward the moving space of the second body 6120 by the pressing force applied from the upper pressing roll 5211a.

The first body 6110 according to the embodiment includes a first body 6111 and a first body (extended) formed to have a longer width (W ₂ ) than the width (W ₁ ) of the moving space of the second body 6120 6111) is formed extending downward from the width of the first body 6111 so that it can be inserted or accommodated in the moving space of the second body 6120 and smaller than the width W ₂ of the first body 6111 and the width W ₁ of the moving space ( W ₃ ) may include a second body 6112.

The shape of the first body 6110 is not limited to the above-described example, and at least a part of the second body 6120 may be inserted into a moving space of the second body 6120 and changed into various shapes that can descend.

The moving part 6130 may include the first body 6110 and the second body so that the second body 6120 is not separated from the first body 6110 or the first body 6110 is separated from the second body 6120. 6120), it is configured to be lowered together with the first body 6110 by a pressing force applied to the first body 6110.

The moving part 6130 according to an embodiment is installed to pass through the moving groove 6122h provided in the second body 6120 so as to penetrate the side wall 6122 of the second body 6120 from the outside to the inside, As a means for fixing the moving member 6131 and the moving member 6131 connected to the first body 6110, the end inserted into the second body 6120 is inserted into the second body 6120. The moving member 6131 is fastened to penetrate, and one surface facing the inner surface of the second body 6120 includes a fastening member 6132 capable of closely contacting the inner surface of the second body 6120.

The moving part 6130 as described above may adjust the movement resistance of the first body 6110 according to the pressing force applied from the lower part of the light pressure 5200 according to the degree of fastening using the fastening member 6132. For example, the moving member 6131 may be a bolt with a thread formed on its outer circumferential surface, and the fastening member 6132 may be a nut with a thread formed on its inner circumferential surface.

At this time, depending on the tightening degree of the fastening member 6132, which is a nut, the adhesive force and frictional force between the fastening member 6132 and the inner surface of the second body 6120 are different. That is, the stronger the adhesion between the fastening member 6132 and the inner surface of the second body 6120, the higher the frictional force. Accordingly, when a pressing force is applied to the head portion 6100 from the upper pressing roll 5211a, resistance to the force that the first body 6110 intends to move downward is strong. Conversely, the weaker the adhesion between the fastening member 6132 and the inner surface of the second body 6120, the frictional force decreases. Accordingly, when a pressing force is applied to the head portion from the upper pressing roll 5211a, the resistance to the force to which the first body 6110 moves downward decreases.

Accordingly, by adjusting the adhesion between the fastening member 6132 and the inner surface of the second body 6120, the downward movement resistance of the first body 6110 can be adjusted according to the pressing force applied to the first body 6110. . In other words, even if the pressing force is applied to the first body 6110, the first body 6110 does not descend, or a small pressing force is applied compared to the pressing force for light pressure reduction of the cast piece S, or from the outside. When a small impact is applied, the problem that the first body 6110 is lowered can be prevented.

A plurality of moving parts as described above may be provided, and may be arranged in the longitudinal direction of the cast piece S on the sidewall of the second body.

As described above, the head portion 6100 according to the embodiment is compressible by pressure applied from the lower pressure portion 5200. To this end, the first body 6110 and the second body 6120 are spaced apart at predetermined intervals before the pressing force is applied to the head 6100. More specifically, the lower surface of the first body 6110 and the lower surface of the second body 6120 are spaced apart from each other.

Hereinafter, when the first body 6110 and the second body 6120 are spaced apart from each other, the space therebetween is referred to as a public portion 6110h. Here, the public portion 6110h is a part of the moving space provided in the second body 6120.

 The reason why the public portion 6110h maintains a predetermined height before the pressing force is applied to the head portion 6100 is that the first body 6110 has resistance to movement by the moving portion 6130.

Here, the separation distance between the first body 6110 and the second body 6120 before the pressing force is applied to the head part 6100 or before the first body 6110 descends, that is, the height of the public part 6110h It is preferably 4 to 12% of the total height of the head portion 6100.

Then, when a pressing force is applied to the first body 6110 by the lowering of the upper pressing roll 5211a, the second body 6120 is fixed, and the first body 6110 moves downward, thereby moving the head portion (6100) is compressed as a whole. That is, the separation distance between the first body 6110 and the second body 6120, that is, the height of the public portion 6110h is reduced, or the lower surface of the first body 6110 and the upper portion of the second body 6120 The surfaces are brought into contact with each other, so that the public portion 6110h disappears (see Figs. 5 (b) and 6 (b)).

On the other hand, if the height of the public portion 6110h is less than 4% before the pressing force is applied to the head portion 6100 or before the first body 6110 is lowered, the reduction force is compared to the pressing force applied from the lower pressure portion 5200. 1 The distance that the body 6110 can descend is small, and a load may be generated in the lower pressure portion 5200 or the casting equipment.

Conversely, before the pressing force is applied to the head portion 6100, or before the first body 6110 is lowered, the height of the public portion 6110h exceeds 12% is the pressing force applied from the lower pressure portion 5200. It may be greater than necessary or unnecessarily large relative to the power.

Accordingly, the height of the cavities 6110h is 4 to 12% of the total height of the heads 6100 before the pressing force is applied to the head 6100 or before the first body 6110 is lowered. . This is controllable by adjusting the adhesion between the fastening member 6132 and the second body 6120 of the moving part 6130 when the lower portion of the first body 6110 is inserted into the second body 6120. .

In the above, it has been described that the fastening member 6132 is located inside the second body 6120 so that one surface is installed in close contact with one surface of the second body 6120.

However, the present invention is not limited thereto, and the fastening member 6132 may be adjusted at any position capable of adjusting the adhesive force with the second body 6120, for example, the fastening member 6132 is located outside the second body 6120. Can be installed.

As described above, when the pressing force is applied to the head portion 6100, compression is possible in response to the pressing force. That is, the pressing force applied from the lower pressure portion 5200 to the head portion 6100 is consumed to compress the head portion 6100, and does not return back to the lower pressure portion 5200 or the casting facility as in the prior art. Thus, even if the pressing force of the lower pressure portion 5200 is applied to the head portion 6100 itself, it is possible to prevent the failure or load of the lower pressure portion 5200 or the casting equipment. Therefore, when the head portion 6100 is located in the light-pressing section SRS, the light-pressing portion 5200 can be pressed down with a light-pressing force for light-pressing the cast piece S.

In other words, when the head part 6100 and the initial cast part connected to it enter the section under light pressure, the upper rolling roll 5211a corresponding to the initial cast part connected to the head part 6100 is lowered, and the initial The cast part can be reduced in pressure.

Accordingly, the initial cast portion connected to the head portion 6100 can be sufficiently reduced, thereby suppressing the occurrence of central segregation and pores in the initial cast portion.

When casting of the cast is finished, the head portion 6100 of the dummy bar 6000 is removed, and the first body 6110 is returned to its original state, that is, before it is compressed.

7 is a view showing a head portion according to a first modification of the embodiment

In the above, it has been described that the head part 6100 is composed of a first body 6110, a second body 6120, and a moving part 6130.

However, the present invention is not limited thereto, and as in the first modified example according to the embodiment shown in FIG. 7, the head portion 6100 is an elastic member inserted into the moving groove 6122h so as to be located below the moving portion 6130 It may include (6140). More specifically, the elastic member 6140 is installed inside the moving groove 6122h to be positioned below the moving member 6131.

At this time, the elastic member 6140 is provided so that the movement resistance of the first body 6110 according to the pressing force applied from the upper pressing roll 5211a becomes a target level. That is, by changing the type, material, structure, etc. of the elastic member 6140, an elastic member 6140 having a desired elastic force is prepared and installed in the moving groove 6122h.

Then, the elastic member 6140, when the pressing force is not applied to the first body 6110, that is, when not compressed, the upper surface of the contact with the moving member 6131, to support the moving member Have a height

Accordingly, the elastic member 6140 acts as a stopper for supporting the moving member 6131 not to move downward when a pressing force is not applied to the first body 6110, and the moving part and the first by the elastic force. It serves to adjust the movement resistance of the body 6110.

In addition, at this time, the moving part 6130 may be provided with only the moving member 6131 which omits the fastening member 6132 and connects the first body 6110 and the second body 6120. Here, as described above, the moving member 6131 functions to connect the first body 6110 and the second body 6120 while moving downward with the downward movement of the first body 6110. And, as described above, the movement resistance of the first body 6110 is adjusted by the elastic force of the elastic member 6140.

In this case, the first body 6110 may be raised to the original position by the restoring force of the elastic member 6140 when the head portion 6100 exits the under-pressure section.

8 is a view showing a head unit according to a second modification of the embodiment.

In the first modified example described above, it has been described that the elastic member 6140 is provided below the moving groove 6122h so as to be positioned below the moving member 6131.

However, the present invention is not limited thereto, and as in the second modified example illustrated in FIG. 8, the elastic member 6140 may be installed in the moving space of the second body 6120 to be located under the first body 6110. . At this time, one end of the elastic member 6140 is fixed to the first body 6110, and the other end is fixed to the second body 6120.

Here, when the pressing force is not applied to the first body 6110, the elastic member 6140 acts as a stopper for preventing the first body 6110 from moving downward, and the moving part 6130 by the elastic force ) And the first body 6110 serves to control movement resistance.

In this case, the first body 6110 may be raised to the original position by the restoring force of the elastic member 6140 when the head portion 6100 exits the under-pressure section.

The elastic member 6140 according to the first and second modified examples may be a block made of a material having elastic force, such as rubber or a spring.

Hereinafter, with reference to FIGS. 1 to 6 and FIG. 9, the operation of the lower part of the pressure and the method of lowering the pressure when applying a dummy bar according to an embodiment of the present invention will be described.

9 (a) to 9 (d) are diagrams for explaining the operation of the lower pressure part according to the movement of the head portion of the dummy bar according to the embodiment of the present invention.

Before casting starts, the dummy bar 6000 is inserted into the mold 20 through the upper opening of the mold 20, and the lower opening of the mold 20 is closed using the head portion 6100. At this time, the main body 6210 and tail part 6220 of the dummy bar 6000 may be located under the mold 20.

Thereafter, molten steel is injected into the mold 20 to primarily solidify the molten steel inside the mold 20. At this time, the molten steel injected into the mold 20 at the beginning of casting solidifies on the head portion 6100 of the dummy bar 6000, whereby the initial cast portion is contacted and connected to the head portion 6100.

Next, the dummy bar 6000 is moved in the extending direction of the cooling table 5000 to draw the head portion 6100 connected to the initial cast portion from the mold 20. The cast piece S drawn from the mold 20 by the movement of the dummy bar 6000 solidifies while moving along the plurality of guide rolls 5110.

Thereafter, when the head portion 6100 of the dummy bar 6000 enters the light pressure lowering section SRS, the driving unit 5220 lowers the upper rolling roll 5211a to become a gap for light pressure reduction of the cast steel S. .

That is, as shown in Fig. 9 (a), the head portion 6100 has not yet reached the light pressure lowering section SRS, and when it is at the previous point, the upper pressing roll 5211a is not lowered. Subsequently, as shown in FIG. 9 (b), when the head portion 6100 enters the lower pressure section, the lower pressure section 5200 is operated. More specifically, when the rear end 6100b of the head portion 6100 of the head portion 6100 directly contacting or connecting with the initial cast portion reaches the starting point P _{1 under} light pressure, the upper rolling-down roll 5211a Descends.

The area in the direction in which the dummy bar 6000 moves is called forward, and the area that has already been passed through is called the rear. Thus, in the moving direction of the dummy bar 6000, the front end of the both ends of the head portion 6100 is referred to as the front end 6100a, and the rear end is referred to as the rear end 6100b.

At this time, among the plurality of upper rolling-down rolls 5211a, the upper rolling-down roll 5211a corresponding to the upper side of the head portion 6100 is lowered. That is, when the rear end 6100b of the head portion 6100 reaches the starting point under light pressure, at least the first upper lower roll HR ₁ is lowered. When the rear end 6100b of the head portion 6100 reaches the starting point P _{1 under} light pressure, a plurality of upper rolling rolls 5211a including the first upper rolling roll HR ₁ above the head portion 6100 ) Is placed, all of them are lowered.

Here, lowering the upper pressing roll 5211a positioned corresponding to the upper side of the head portion 6100 means that, among the plurality of upper pressing rolls 5211a, the upper pressing roll 5211a located directly above the head portion 6100. ) Means to descend.

Subsequently, when the dummy bar 6000 is further moved, as shown in FIGS. 9 (c) and 9 (d), the cast piece S enters the lower pressure section SRS. And, the position of the head portion 6100 is changed in real time by the continuous movement of the dummy bar 6000.

At this time, according to the position change of the head portion 6100, the upper rolling-down roll 5211a corresponding to the upper side of the head portion 6100 is lowered. Further, the upper rolling-down roll 5211a in the position where the head part 6100 has passed or passed does not rise again even when the head part 6100 passes, and maintains the lowered state.

In other words, from the upper rolling-down roll 5211a located at the starting point (P ₁ ) under the light pressure to the upper rolling-down roll 5211a located above the head portion 6100 at the present time. In addition, the upper rolling-down roll 5211a located in front of the head portion 6100 is not yet lowered.

By this operation, the plurality of upper rolling rolls 5211a positioned in the light-pressing section SRS are sequentially pressed. Thus, as shown in Figure 9 (d), when the head portion 6100 is out of the light pressure end point (P ₂ ), the plurality of upper rolling-down roll (5211a) located in the light-pressing section (SRS) all descended State.

And, even if the head portion 6100 deviates from the end point P ₂ under the light pressure, the plurality of upper rolling rolls 5211a maintains the lowered state, and the cast steel S continuously in the light pressure section SRS. It enters and becomes pressured.

10 (a) to 10 (c) are views for explaining the operation of the lower pressure according to the third modification of the embodiment.

In the above, when the rear end of the head portion 6100 reaches the starting point P ₁ under light pressure, the upper rolling-down roll 5211a corresponding to the head portion 6100 is lowered.

However, this is not limited, as in the third modified example shown in Figure 10, the head portion 6100 is the soft reduction starting point through the (P _1), the soft reduction starting point (P ₁₎ and the soft reduction end When located between the points P ₂ (see FIG. 10 (c)), the upper rolling roll 5211a corresponding to the upper side of the head portion 6100 and the upper rolling roll located at the rear side of the head portion 6100 (5211a) can be lowered to start under pressure.

In this way, even when lowering the upper rolling roll to pass through the soft reduction starting point (P _1), the soft reduction starting point when the head portion 6100 located between the (P ₁₎ and the soft reduction end point (P _2), Since the upper rolling roll (5211a) is lowered, when the head portion (6100) is out of the light-loading end point (P ₂ ), compared to the prior art of lowering the upper rolling roll (5211a), the time point of pressing the initial cast part is advanced You can.

On the other hand, conventionally, as shown in FIG. 11, even if the head portion 610 enters the lower pressure section SRS (FIG. 11 (a)), the upper rolling roll 5211a is not lowered. More specifically, even if the head portion 610 and the initial cast part connected to the head portion 610 have entered the lower pressure section SRS, the upper pressing roll 5211a is not lowered or the upper pressing roll 5211a The upper rolling-down roll 5211a was not lowered so that the gap between the lower rolling-down rolls 5211b became a gap for the lower pressure of the cast piece S.

And, as shown in Figure 11 (b), when the head portion 610 is completely out of the pressure drop section (SRS), by lowering the plurality of upper pressing roll (5211a), the gap for the pressure drop of the cast steel (S) Adjusted as much as possible. In other words, when the rear end 610b of the head portion 610 is out of the light pressure ending point P ₂ , lowering the plurality of upper rolling rolls 5211a of the light pressure lowering section SRS starts the light pressure lowering. Did.

This is because, when the dummy bar 600 is passing through the light-pressing section, when the pressing force of the light-loading lower part 5200 is applied to the dummy bar 600, the dummy bar 600 cannot absorb it, and conversely This is because a safety accident may occur due to a load on the lower pressure 5200 or a casting facility. Therefore, in the related art, as described above, when the light-pressing section SRS completely exits to the head portion 610 of the dummy bar 600, the cast steel S is reduced.

However, in this case, there is a problem that the pressing against the initial cast part connected to the head part 610 becomes insufficient. This is because the head portion 610 performs the pressure reduction only after the light pressure section SRS is removed, even if the initial cast part connected to the head portion 610 passes through the light pressure section SRS, the head portion ( If the 610) did not pass the light pressure section (SRS), it is because light pressure is not performed. Therefore, there is a problem in that the pressure drop on the initial cast portion connected to the head portion 610 is insufficient, so that the central segregation and pores are not removed or insufficient, the quality of the initial cast portion is deteriorated.

However, in the embodiments of the present invention, as described above, when the head portion 6100 of the dummy bar 6000 enters the lower pressure section SRS, the pressure to lower the slab S is reduced to the head portion 6100. ), The upper pressing roll 5211a corresponding to the head portion 6100 is lowered. And, as the head portion 6100 moves, the upper roll-down roll 5211a corresponding to the upper side of the head portion 6100 at the present time point and the upper portion corresponding to the previous area of the head portion 6100 at the present time point. The rolling roll 5211a is in a lowered state. Thus, while passing through the light-pressing section SRS, the light-loading force of the cast piece S is applied to the head part 6100, and the initial cast-piece part connected to the head part 6100 is the light-loading starting point P ₁ Light pressure is continuously applied from until the end point (P ₂ ) under light pressure is reached.

Therefore, it is possible to sufficiently reduce the initial cast portion, it is possible to suppress or prevent the occurrence of central segregation and pores, thereby improving the quality of the initial cast portion compared to the prior art. In addition, there is an effect that can reduce the length of the initial cast portion to be cut.

5200: Lower pressure 5210: Abha roll
5211a: Upper rolling roll 5211b: Lower rolling roll
6100: head portion 6100: first body
6120: second body 6100a, 610a: shear
6100b, 610b: rear end 6130: moving part
6131: moving member 6122h: moving groove
6140: elastic member 6200, 620: body
6210, 621: main body 6220, 622: tail

Claims (17)

As a dummy bar for drawing a cast from the mold and moving the cast in the casting direction,
A head part that can be inserted into the mold and is compressed by being partially moved in the thickness direction of the cast piece by a pressing force applied from the outside; And
A body portion formed extending from the head portion;
Dummy bar comprising a. The method according to claim 1,
The head portion is arranged in the thickness direction of the cast, and includes a first body and a second body interconnected,
The first body is a dummy bar movable in the direction of the second body by a force applied from the outside of the first body. The method according to claim 2,
At least a portion of the first body is accommodated in the second body, and a movement space in which a direction in which the first body is located is opened is provided.
At least a portion of the first body is dummy bar that can be inserted into the moving space. The method according to claim 3,
A dummy bar installed to penetrate the sidewall of the second body surrounding the moving space, the end inserted into the second body is connected to the first body, and includes a movable portion movable with the first body . The method according to claim 4,
The side wall of the second body is provided with a moving groove formed in an inward direction from the outside of the side wall, so that the moving portion can penetrate therethrough
The moving groove is a dummy bar formed to extend in the moving direction of the first body on the side wall. The method according to claim 5,
The moving part,
A moving member installed to penetrate the moving groove of the second body and having an end inserted into the second body connected to the first body; And
A fastening member which is located inside the second body and is installed to allow the moving member to pass therethrough, and can adjust an adhesive force with an inner surface of the second body;
Dummy bar comprising a. The method according to claim 5,
The moving part is installed to penetrate the moving groove of the second body, the end inserted into the second body includes a moving member connected to the first body,
A dummy bar which is installed inside the moving groove so as to be located under the moving member, and includes an elastic member having elastic force. The method according to claim 2,
A dummy bar including an elastic member that is installed to connect between the first body and the second body inside the second body and is capable of stretching and contracting with movement of the first body. Drawing a head portion of the dummy bar and a cast piece connected to the head portion from the mold;
A step of continuously moving the dummy bar from the lower side of the mold to solidify the cast steel drawn from the mold; And
A step of lowering the cast piece entered into the lower pressure section provided under the mold;
Including,
In the process of lowering the cast iron,
When the head portion enters the lower pressure section, a process of lowering, among the plurality of upper pressing rolls, an upper pressing roll corresponding to an upper side of the head portion and an upper pressing roll located behind the head portion in the lower pressing section. Casting method comprising a. The method according to claim 9,
In lowering the upper rolling roll located in the upper portion and the lower portion of the head portion corresponding to the upper portion of the lower portion in the lower pressure section,
A casting method of lowering only the head portion that has entered the light-pressing section, or pressing a head portion that has entered the light-pressing section and a cast piece that has entered the light-pressing section and is located behind the head. The method according to claim 10,
The light-pressing section is from the point where the first upper rolling roll is located to the point where the last upper rolling roll is located, among the plurality of upper rolling rolls,
The position of the first upper roll-down roll is the starting point under light pressure,
And when the rear end of the head portion connected to the cast piece reaches the starting point under the light pressure, lowering the upper rolling roll positioned corresponding to the upper side of the head portion. The method according to claim 10,
The light-pressing section is from the point where the first upper rolling roll is located to the point where the last upper rolling roll is located, among the plurality of upper rolling rolls,
The position of the first upper roll-down roll is the starting point under light pressure,
The position of the last upper roll-down roll is the end point under light pressure,
When the rear end of the head portion is located between the start point and the end point under the pressure after the start point under the pressure, the casting method comprising the step of lowering the upper pressing roll corresponding to the upper side of the head portion. The method according to claim 9,
The casting method in which the head portion passes through the light-pressing section, and the upper roll-down roll positioned at the rear of the head portion at the present time maintains the lowered state from the previous time. The method according to any one of claims 9 to 13,
In the lowering of the upper pressing roll corresponding to the upper side of the head portion,
A casting method in which a part of the head portion is moved in the thickness direction of the cast and compressed by a pressing force applied from the upper pressing roll. The method according to claim 14,
The head portion is provided with a first body that is movable by a pressing force applied from the upper pressing roll and a moving space in which at least a portion of the first body can be accommodated, and a direction in which the first body is located is opened. It includes a second body,
Casting method for compressing the first body to reduce the moving space of the second body by the pressing force applied from the upper pressing roll. The method according to claim 15,
Before starting the casting, the process of fastening the moving part so that the end is connected to the first body through the side wall of the second body surrounding the moving space; And
Adjusting the adhesion between the moving part and the second body to adjust the moving resistance of the first body;
Casting method comprising a. The method according to claim 15,
After the casting is finished, the casting method comprising the step of returning the first body moved in the direction of the second body by the pressing force applied from the upper pressing roll to the state before pressing.

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