KR100775091B1 - Mold for continuous casting machine - Google Patents

Abstract

A mold for a continuous casting apparatus is provided to reduce a friction force between an inner corner of a mold and a congealed shell by forming a chamfer on the inner corner of the mold. A mold(100) for a continuous casting apparatus comprises a couple of major plates(110) that face each other and a couple of minor plates(120). Molten steel or a mold flux is charged into the mold. The minor plates have two lateral sides that are slidably installed at ends of the major plate. The minor plate has a chamfer at two inner ends thereof. The chamfer has a radius of curvature, which becomes gradually increased from an upper side to a lower side of the mold. The mold flux is injected into the mold in a melted state.

Description

Mold of Continuous Casting Equipment {MOLD FOR CONTINUOUS CASTING MACHINE}

1 is an overall perspective view of a typical continuous casting device.

2 is a cross-sectional view of the mold in the continuous casting operation by a conventional method.

3 is a perspective view of a mold according to the present invention.

4 is a partial cross-sectional perspective view of the mold according to the present invention.

Fig. 5A is a plan sectional view of a mold having a conventional orthogonal edge, and Fig. 5B is a plan sectional view of a mold having a corner formed with the present invention curved portion.

<Description of Symbols for Main Parts of Drawing>

10, 100: mold 11: solidified shell

12: molten steel 20: ladle

21 liquid layer 27 slag film

29: slag bear 30: tundish

32: immersion nozzle 40: ladle turret

50: cast 60: dummy bar

70: dummy bar head 80: feed roller

90: automatic cutter 110: long side plate

120: short side plate R: curved portion

The present invention relates to a mold of a continuous casting device, and more particularly, to form a curved portion at the inner edge of the mold to reduce the frictional force generated at the inner edge of the mold and the solidification shell to reduce the frequency of the break-out casting Relates to a mold of the apparatus.

In general, the continuous casting device is composed of a facility for continuously producing a cast of a constant size by receiving the molten steel produced in the steel mill and transported to the ladle to the mold.

1 is an overall perspective view of a typical continuous casting device. Referring to the drawings, the ladle 20 installed in the ladle turret 40 is filled with molten steel in which impurities are removed and chemical composition is adjusted, and the molten steel in the ladle 20 is filled. Pour into a tundish 30 through a nozzle of cylindrical refractory brick.

The molten steel stored in the tundish 30 is injected into the mold 10 through the immersion nozzle 32 made of a cylindrical refractory brick, and cast into a slab on a large plate by the mold. Since the mold 10 is provided with a cooling mechanism therein, the molten steel is cooled while the molten steel is introduced to cast a cast 50 having a cross section corresponding to the cross section of the mold 10.

In the mold 10, a dummy bar 60, which guides the cast piece 50, is introduced into an open lower portion of the mold 10, and the first molten steel introduced into the mold 10 is a dummy bar head 70. As the plurality of rollers 80 installed in the moving track are solidified by the boundary of the uneven part of the drive, the dummy bar 60 leads the solidified slab 50 and moves between the upper and lower rollers to which the coolant is sprayed. Are manufactured.

In the initial casting of molten steel, the slab 50 solidified by the dummy bar 60 is drawn out, but once the solidified slab 50 passes between the transfer rollers 80, the role of the dummy bar 60 is thereafter. It is not necessary. Therefore, the dummy bar 60 is raised upward by the separating device, and the continuously cast slab 50 is cut into a predetermined length by the automatic cutter 90 and is transferred to the collecting cabinet by the table roller 82.

The mold 10 of the continuous casting device has no bottom unlike the ingot mold. Therefore, when the molten steel is injected into the initial casting mold 10, a bottom for preventing the molten steel from being positioned inside the mold is required, and the dummy bar 60 serves as a role thereof. The tip portion of the dummy bar 60, that is, the portion corresponding to the mold bottom, is called the dummy bar head 70, and the initial molten steel solidifies at this portion, is coupled to the dummy bar 60, and drawn out by the transfer roller 80. .

In addition, when molten steel is supplied to the mold 10, not only molten steel but also an auxiliary mold flux is supplied to the mold 10. When the molten steel draws molten steel from the mold 10, the molten steel is cast into the mold 10. Lubricate to make it easier to get out of the.

2 is a cross-sectional view of the mold in the continuous casting operation by a conventional method. Referring to the drawings, the mold flux supplied into the mold 10 is mainly in powder or granule form, and has a specific gravity lower than that of the molten steel 12 and has a low melting point so that the mold 10 is not mixed with the molten steel 12 in the mold 10. It is located on the molten surface corresponding to the uppermost layer of the molten steel.

At this time, the mold flux located on the molten surface forms a liquid layer 21, a sintered layer (semi-melt layer) 23 and a powder layer 25 sequentially while melting by molten steel. After the powder or granular mold flux is dissolved, a part of the mold flux solidifies again on the inner wall of the mold 10 to form a solid slag film 27, and a liquid layer between the slag film 27 and the solidified shell 11. As the molten slag of 21 is introduced, it controls the heat transfer between the molten steel 12 and the mold 10 and improves the lubrication action.

In this case, a slag bear 29 is formed between the slag film 27 into which the molten slag flows and the solidification shell 11 toward the inside of the mold 110. The slag bear 29 is a slag film 27. The molten slag is prevented from flowing between the solidified shell 11) and the solidified shell 11 so that the solidified shell 11 breaks when the molten steel is drawn through the lower portion of the mold, causing break-out of the molten steel therein.

That is, the inner edge of the mold 10 has a high static friction of the molten steel 12 has a high frictional force compared to other parts, so that the solidified shell 11 is easily broken or a non-uniform strain on the surface of the solidified shell 11 ( strain) to cause defects such as cracks on the surface of the cast piece 50 passing through the mold 10.

In particular, when the mold flux is injected into the mold 10 in a molten state, the liquid layer positioned in the middle of the slag film 27 and the solidification shell 11 becomes thick, thereby delaying the formation of the solidification shell 11 ( The thickness of the solidification shell is thinner). In this state, when the iron static pressure of the molten steel is concentrated at the inner edge of the mold, a constraint occurs between the solidification shell 11 and the mold 10 to generate a break-out.

The present invention is to solve the above problems, by changing the structure of the mold to reduce the friction force generated in the inner edge of the mold and the solidification shell to reduce the frequency of break-out occurs and improve the quality of the cast The purpose is to provide a mold of a continuous casting apparatus.

According to the technical idea of the present invention for achieving the above object, in the mold of the player in which molten steel and / or mold flux is loaded, a pair of long side plates facing each other and both sides of the long side plate are slid. A short side plate that is possibly inserted, wherein the short side plate is achieved by a mold of a continuous casting apparatus, characterized in that curved portions are formed at both ends of the inner surfaces facing each other.

Here, it is preferable that the radius of curvature of the curved portion increases from the upper side to the lower side of the mold.

In addition, it is preferable to inject the mold flux into the mold in a molten state.

Hereinafter, embodiments according to the present invention will be described in more detail with reference to the accompanying drawings.

3 is a perspective view of a mold according to the present invention.

Referring to the drawings, the mold 100 according to the present invention has an approximately rectangular shape on the inside and the upper and lower portions are opened so that the immersion nozzle and the dummy bar head of the tundish are respectively inserted and positioned. The mold 100 forms an inner side where the molten steel injected through the immersion nozzle stays solidified for a while, and the inner shape of the mold 100 has a shape corresponding to the shape of the slab to be produced, so that the inner edge is not orthogonal. Form.

That is, the inner shape of the mold 100 is a long side plate 110 and a short side plate (respective of the slab, bloom, billet (Billet) type of the long side plate 110 to form a pair respectively) And a frictional force generated at the inner edge of the mold 100 and the solidification shell by forming a curved portion R having a rounded shape such that the corners between the long side plate 110 and the short side plate 120 are not orthogonal to each other. Decreases.

Here, the reduction of the frictional force generated between the inner edge of the mold 100 and the solidification shell will be described by way of example.

Usually, the frictional force is the resistance generated on the contacted surface when two objects are in contact, but in actual phenomenon, it corresponds to the area where the two objects are in contact. Therefore, when comparing the area of the conventional orthogonal corner and the corner having the curved portion of the present invention is as follows.

Fig. 5A is a plan sectional view of a mold having a conventional orthogonal edge, and Fig. 5B is a plan sectional view of a mold having a corner formed with the present invention curved portion. As shown in the figure, the area of the part having the length a and the length b around the vertex P that the long plate 110 and the short plate 120 contact each other is (a + b) × the height of the mold. That is, assuming that a length is 1000 mm in the long plate 110, b length is 1000 mm in the fragment plate 120, and 2000 mm in height, the area of the orthogonal edge is 4000 cm 2.

On the other hand, the partial area of the radius R that satisfies the length a and length b around the same vertex P is the height of (2 × circumference × R) × (center angle / 360 °) × mold. That is, if a radius satisfying the length a and length b is 1000 mm and the mold has a height of 2000 mm, the center angle is 90 °, so the area of the corner where the curved portion is formed is 3140 cm 2.

As shown above, when the curved portion R is formed at the inner corner of the mold of the present invention, the area of the mold in contact with the solidification shell is reduced as compared to the conventional orthogonal corners, and as a result, the frictional force generated at the solidification shell and the inner corner of the mold is reduced. This reduces the frequency of breakout during continuous casting.

On the other hand, the curved portion (R) formed at the inner edge of the mold is preferably formed in the fragment plate 120. This will be described based on FIG. 4.

4 is a partial cross-sectional perspective view of the mold according to the present invention. Referring to the drawings, in order to adjust the width of the slab to be produced, the mold 100 has a predetermined length and a pair of long side plate 110 facing each other, and the left and right ends between the long side plate 110 In the short side plate 120 is inserted so that both sides are slidable. The short side plate is connected to a transfer unit (not shown) for sliding the short side plate on either side except for the inner side surfaces facing each other.

In particular, a curved portion R is formed in the short side plate 120, and the curved portion R is formed at both ends of the inner side surfaces of the short side plate 120 facing each other. Therefore, even when the fragment plate 120 slides between the long plate 110 to adjust the width of the mold to be produced, the edges at which the long side plate 110 and the short side plate 120 contact each other are not perpendicular to each other. The frictional forces generated at the inner edge of the mold 100 and the solidification shell are reduced.

And, the curved portion (R) formed on the inner edge of the mold 100 is different in shape to form a folded radius (oscillation mark) formed on the surface of the cast by increasing the radius of curvature from the upper side to the lower side of the mold 100 ) And duty free to reduce cracks. In other words, the radius of the curved portion R2 formed in the lower portion is larger than that of the curved portion R1 formed in the upper portion of the fragment plate 120.

Here, the folds generated on the surface of the cast is a phenomenon caused by the vibration of the mold, and usually causes the mold to vibrate so that the molten steel solidified inside the mold can be drawn more easily. As the molten steel solidified from the inside shakes up and down slightly along the mold, the solidification shell is overlapped to generate a folding defect.

In other words, when the inner surface is vertically formed in the conventional mold, the molten steel supplied to the mold through the immersion nozzle forms a solidification shell vertically along the inner surface. When the solidification of the molten steel proceeds to some extent, the mold is vibrated to draw the molten steel. Accordingly, the vibration causes the solidification shell formed along the inner surface of the mold to shake up and down to generate a vertical load onto the solidification shell. At this time, one part of the coagulation shell, which is more vulnerable than the other part, is collapsed, thereby creating a fold defect.

Since the folding flaw is a factor of lowering the quality of the cast steel, the inner edge of the mold is formed so that the rounded shape of the curved portion increases from the upper side to the lower side so that the folding flaw does not occur, thereby reducing the cracks in the folding flaw and duty free. You can.

That is, when the curved portion R, which increases from the upper side to the lower side, is formed at the inner edge of the mold 100, the inner side of the mold 100 has a trapezoidal shape in which the upper portion thereof is narrower than the lower portion thereof. Accordingly, the solidification shell is inclined to contact the inner surface of the mold at an angle as compared to the molten steel solidifying the inner surface of the mold 100, that is, the solidification shell is perpendicular to the inner surface of the mold. Even if vibration is generated in the mold by dispersing the vertical load generated in the phase, the flaw is not generated on the surface of the cast, thereby improving the quality of the cast. This will be described in detail based on the experimental example.

Experimental Example

  Casting condition  Component (carbon concentration, Wt%)  Casting speed (m / min)  NSR (%)  Flux consumption (kg / ㎡)  0.0010  1.6  1.0  0.55  Analysis item  Inventive Example  Conventional Comparative Example  Frequency of fold flaw (number / m)  One  10  Breakout frequency  0  5

As shown in the experimental example, the experiment was performed by applying the structure of the mold according to the present invention under the same casting conditions. It can be seen that the frequency of breakage occurrence and the breakout frequency are significantly reduced in the cast produced in the mold having the curved portion of the present invention compared to the mold having the orthogonal corner.

In addition, the molten steel solidified in the mold structure as described above can be supplied in the molten state by lubricating the mold flux so as to easily escape from the mold, it is possible to double the effect of the mold structure according to the present invention. That is, when the molten mold flux is supplied to the mold, a part of the molten mold flux is solidified along the inclined inner wall of the mold to form a slag film by cooling means (not shown) provided in the mold. In the space secured between the solidification shell of the molten steel and the inner wall of the mold, the inflow of the molten mold flux increases, thereby improving lubrication.

On the other hand, the present invention is not limited only to the embodiments described above, but can be modified and modified within the scope not departing from the gist of the present invention, it should be seen that such modifications and variations are included in the technical idea of the present invention. do.

For example, in the above description, the mold is described as consisting of a long plate and a fragment plate, but in some cases, the long plate and the fragment plate are not separable but integrally formed, and a curved portion is formed at the inner edge of the integrally formed mold. Can be formed.

In addition, in the above description, the mold flux may be performed by melting, and in some cases, powder or granular mold flux may be supplied to the mold.

In addition, in the above description, the coagulation shell has been described as being in contact with the inside of the mold for clarity, but the coagulation shell is in direct contact with the inside of the mold, or as shown in FIG. 2, the slag film solidifies the inner wall of the mold. And a liquid layer may be located between the slag film and the solidification shell.

In the mold of the continuous casting apparatus according to the present invention, a curved portion is formed at the inner corner of the mold, thereby reducing the area of contact with the solidifying shell as compared with the conventional orthogonal corners, and as a result, reducing the frictional force generated at the solidifying shell and the inner corner of the mold. By reducing the occurrence frequency of the break-out and improve the quality of the cast, in particular, the effect is increased when the mold flux is injected into the mold according to the present invention in a molten state.

Claims (3)

In the mold of the player in which molten steel or mold flux is charged, A pair of long side plates facing each other, A short side plate on which both sides are slidably inserted at an end of the long side plate, The short side plate forms curved portions at both ends of the inner surface facing each other, The radius of curvature of the curved portion is a mold of a continuous casting device, characterized in that the larger from the upper side downward. The mold of a continuous casting apparatus according to claim 1, wherein the mold flux is injected into a mold in a molten state. delete

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