KR20090067574A - A casting equipment for continuous strip and continuous casting method of the same - Google Patents

Abstract

An apparatus for continuous casting of a board material and a casting method using the same are provided to improve quality of the board material by preventing a surface crack of a thin plate with load applied on a pair of rollers. An apparatus for continuous casting of a board material comprises the followings: a rolling unit adding pressure to molten metal with a pair of rotating rollers(124); a control unit controlling operation of the rolling unit; a melting furnace forming the molten metal by heating a material; and a molten metal injection unit(180) injecting the molten metal. The molten metal injection unit is installed on the roller located on the bottom and the roller located on the top with different contact areas.

Description

Sheet continuous casting apparatus and sheet continuous casting method using same {A casting equipment for continuous strip and continuous casting method of the same}

1 is a schematic view showing the configuration of a plate continuous casting apparatus according to the prior art.

Figure 2 is a perspective view showing the configuration of a plate continuous casting apparatus according to the present invention.

Figure 3 is a schematic view showing the state of the molten metal injection means and the roller showing the main part of the continuous plate casting apparatus according to the present invention.

Figure 4 is a schematic view showing another embodiment of the molten metal injection means and the roller constituting the main portion of the plate continuous casting apparatus according to the present invention.

Figure 5 is a flow chart showing a plate continuous casting method using a plate continuous casting apparatus according to the present invention.

6 is a configuration diagram of an embodiment and a comparative example of a plate continuous casting method using a plate continuous casting apparatus according to the present invention.

7 is a comparison photograph showing the surface state of the plate produced using FIG.

8 is an experimental result showing a solid-liquid interface state when the rotational speed of the roller in the continuous plate casting apparatus according to the present invention.

Figure 9 is a photograph showing the surface state of the plate when the amount of cooling water provided to the roller in the plate continuous casting apparatus according to the present invention.

Explanation of symbols on the main parts of the drawings

100. Sheet continuous casting device 120. Rolling means

122.Frame 124.Roller

125. Cooling water furnace 140. Control means

142. Operation Buttons 144. Display

160. Melting furnace 180. Melt injection means

182.Tundish 184.Nozzle

186. Inlet A. Cross angle

 P. Plate S100. Injection unit installation stage

S200. Roller rotation step S300. Molten Supply Step

S400. Melt injection step S500. Molten solidification stage

S600. Plate Withdrawal Step

The present invention relates to a plate continuous casting apparatus and a plate continuous casting method using the same, and more particularly, a continuous plate casting apparatus for controlling the liquid-liquid interface asymmetrically to reduce the surface cracks during continuous casting of aluminum and magnesium and using the same It relates to a sheet continuous casting method.

In general, in order to manufacture the aluminum or magnesium alloy in a plate state, it is subjected to a multi-step process, such as ingot casting, homogenization treatment, face grinding, hot rolling, cold rolling, intermediate heat treatment, cold rolling.

This causes a very high process cost of the material.

In particular, the Al-Mg alloy or magnesium alloy having a magnesium content of more than 2wt% compared to 100wt% of the alloy has a low rolling property and is additionally required as an intermediate heat treatment process during hot and cold rolling.

Therefore, many process steps are required and the process cost is very high when rolling in thickness less than 5mm from the ingot.

The sheet continuous casting method was developed as a method to lower the process cost. Until now, sheet continuous casting has been mainly used for the production of pure aluminum based sheet. However, as the demand for sheet materials for high strength aluminum alloys and magnesium alloys increases, research is being conducted to produce the sheet at low cost by applying the sheet casting method.

In particular, in the case of twin-roll thin sheet casting method, the thickness of the final casting material during the thin plate casting can be compressed to 1 to 5 mm, and since the additional rolling process cost is very small, it is known to be the most economical method of producing the thin plate.

In the case of a general twin-roll type sheet casting machine, the molten metal poured into the tundish is supplied between the cooling rolls through the nozzle part of the upper and lower symmetry to be cast so as to solidify the molten metal and form a sheet at the same time.

That is, Korean Patent Application No. 0757586 discloses a continuous casting method of aluminum-magnesium alloy plate material.

Referring to Figure 1 briefly, a pair of rolls 10 of the same diameter is provided, the left side of the pair of rolls (10) to accommodate the melting furnace and crucible 13 and the molten metal provided from the crucible (13) And a tundish 14 which guides to the inlet of 10).

The pair of rolls 10 are rotated in opposite directions to guide the molten metal in the right direction, and the molten metal is rolled to a thickness corresponding to the distance from which the pair of rolls 10 are spaced from each other to form the plate 12.

The tundish 14 is configured not to be melted by the heat of the molten metal, and the nozzle 15 is provided at the right end of the tundish 14. The nozzle 15 has a shape corresponding to the left exterior shape formed by the pair roll 10, and is formed to be symmetrical up / down with respect to the center.

However, the continuous casting method configured as described above has the following problems.

When the molten metal is in contact with the roll during thin plate casting, the length of contact is about 50mm, and it is made in a very short time.In particular, in the case of an alloy molten metal having a large range of liquid-liquid coexistence temperature ranges containing a lot of alloying elements, a healthy plate can be obtained. There is a difficulty in finding the condition.

In particular, the inner segregation may be very severe depending on the shape of the solid-liquid interface of the plate cast at the roll inlet during sheet casting, and during the sheet casting, the solidification of the molten metal in contact with the roll is unevenly progressed to generate fine cracks. When stress is applied in a high state, cracks propagate along grain boundaries, and eventually many cracks are generated at the edges of the surface or the plate.

In addition, the above problems cause a defect of the plate, and in order to find a stable process condition in order to solve this problem, there is a problem that the investment cost is increased because the device design and additional process control device is required.

An object of the present invention for solving the above problems, and relates to a plate continuous casting apparatus and a plate continuous casting method using the same controllable so that the solid-liquid interface is asymmetrical shape during continuous casting of aluminum and magnesium.

Another object of the present invention is to control the solid-liquid interface in an asymmetrical shape to a plate continuous casting apparatus to minimize defects such as surface cracking and plate continuous casting method using the same.

Plate continuous casting apparatus according to the present invention for achieving the above object is provided with a pair of rotating rollers for applying pressure to the molten metal, control means for controlling the operation of the rolling means; And a molten metal furnace for forming a molten metal by applying heat to the material, and a molten metal injection means for receiving molten metal from the molten metal and injecting the molten metal into the rolling means. And it is characterized in that it is installed to have a different contact area on the roller located on the lower side.

The molten metal injection means includes a tundish in which the molten metal is temporarily stored and a nozzle for guiding the molten metal stored in the tundish to the rolling means. The surface is formed in parallel with the tangent of the roller is characterized in that the injection port for guiding the moving direction of the molten metal to the rolling means.

The nozzle has an asymmetrical cross-sectional shape of the upper and lower parts with respect to the center.

The end contour of the nozzle corresponds to a part of the contour formed by the pair of rollers.

The extension line of the nozzle is characterized by forming an acute angle or an obtuse angle with a line segment following the rotation center of the pair of rollers.

Sheet continuous casting apparatus according to the present invention is provided with a pair of rotating rollers for applying pressure to the molten metal, control means for controlling the operation of the rolling means, and applying heat to the material to form the molten metal And a molten metal injection means for receiving the molten metal from the melting furnace and injecting the molten metal into the rolling means, wherein the pair of rollers rotate at different rotational speeds to form an asymmetric solid-liquid interface. It is done.

Sheet continuous casting method using a plate continuous casting apparatus according to the present invention is a pair of rollers and the injection means installation step of installing the asymmetrical nozzle for guiding the melt from one side of the molten metal injection means contact with each other, and the pair of rollers A roller rotation step of providing rotational power to rotate in different directions, a molten metal supplying step of supplying molten metal into the molten metal injection means, and injecting the molten metal supplied to the molten metal between the pair of rollers; It is characterized in that it comprises a molten metal injection step, a molten metal solidification step in which the molten metal injected between the pair of rollers is pressed and solidified, and a sheet material extraction step for withdrawing the plate formed solidified by the pair of rollers.

The injection means installation step is characterized in that the inner bottom surface of the injection port provided in the nozzle to match the roller tangent of the lower side.

The roller rotating step is characterized in that the process of the roller to rotate at different rotational speeds.

According to this invention which has such a structure, there exists an advantage that the defects, such as a crack, reduce and productivity improves.

Hereinafter, a configuration of a plate continuous casting apparatus (hereinafter referred to as a 'casting apparatus') according to the present invention will be described with reference to FIG. 2.

Figure 2 is a perspective view showing the configuration of a plate continuous casting apparatus according to the present invention.

As shown in the drawing, the casting apparatus 100 applies rolling pressure to the molten metal to form a plate (reference numeral P in FIG. 3) and a control means 140 for controlling the operation of the rolling means 120. And a melting furnace 160 that forms a molten metal by applying heat to the material, and a molten metal injection means 180 that receives the molten metal from the melting furnace 160 and injects the molten metal into the rolling means 120.

The rolling means 120 is formed mostly by the frame 122, the inside of the frame 122 is provided with a pair of rollers 124 having the same size and shape. The roller 124 is for rolling the molten metal by receiving rotational power and rotating in different directions, and configured to control the separation distance.

The cooling water passage 125 is provided inside the roller 124. The cooling water passage 125 is configured to cool the molten metal by absorbing heat of the molten metal through a roller 124, and a plurality of cooling water passages 125 are provided radially.

Therefore, when the roller 124 is rotated to roll the molten metal, the roller 124 is in contact with the molten metal in a cooled state to help solidify the molten metal.

A power motor 126 is provided at the right end of the roller 124. The power motor 126 generates rotational power when power is applied, and is axially coupled to the roller 124 to provide such rotational power to the roller 124.

The power motor 126 is electrically connected to the control means 140. In addition, the control means 140 is provided with a plurality of operation buttons 142 for operating the operation of the rolling means 120 and the display window 144 indicating the operating state of the rolling means 120.

Therefore, the user can control the operation of the rolling means 120 by operating the operation button 142, the operation state of the rolling means 120 can be confirmed through the display window (144).

The melting furnace 160 is provided on the left side of the rolling means 120. The melting furnace 160 is to form a molten metal by heating and melting the first material (solid state material) of the plate (P) to be manufactured by the rolling means 120, although not shown in the interior of the melting furnace 160 A crucible into which the material is introduced and a heating body that heats the injected material are provided.

The left side of the rolling means 120 is provided with a molten metal injection means 180 that is a main component of the present invention. The molten metal injection means 180 is configured to receive the molten metal from the melting furnace 160 to provide the molten metal between the rollers 124.

Hereinafter, a detailed configuration of the molten metal injection means 180 will be described with reference to FIGS. 3 and 4.

Figure 3 is a schematic view showing the state of the molten metal injection means and the roller showing the main portion of the continuous plate casting apparatus according to the present invention, Figure 4 and the molten metal injection means constituting the main portion of the plate continuous casting apparatus according to the present invention; A schematic diagram showing the appearance of another embodiment of a roller is shown.

As shown in the figure, the molten metal injection means 180 has an upper right opening, an left end opening to the left, and the inside communicates with the tube to guide the molten metal from right to left.

To this end, the molten metal injection means 180 includes a tundish 182 in which the molten metal is temporarily stored, and a nozzle 184 for guiding the molten metal stored in the tundish 182 to the rolling means 120. It is composed.

The tundish 182 is opened at the left end so that the molten metal is accommodated therein and the received molten metal is guided in the left direction, and the opened left end communicates with the right end of the nozzle 184.

The nozzle 184 is formed integrally with the tundish 182, and is formed of a material that is insoluble in a high temperature molten metal together with the tundish 182.

The injection hole 186 is formed in the left and right sides of the nozzle 184 to have a rectangular longitudinal section. The inlet 186 is to allow the molten metal stored in the tundish 182 to be guided to the outside through the nozzle 184, the roller 124 is formed higher than the distance separated from each other, The contact area with the upper roll is larger than the contact surface with the lower roll.

In addition, the level of the molten metal in the tundish 182 is formed higher than the distance the pair of rollers 124 are spaced apart from each other.

Therefore, when the molten metal moved through the injection hole 186 is guided between the rollers 124, the roller 124 rolls the molten metal.

The left exterior of the nozzle 184 has a shape corresponding to a portion of the right exterior formed by the pair of rollers 124. Therefore, the appearance of the nozzle 184 has an asymmetrical cross-sectional shape of the upper and lower parts with respect to the center, and when the nozzle 184 approaches between the pair of rollers 124, the outer surface of the nozzle 184 Is in contact with the pair of rollers 124.

More specifically, the upper surface of the left side of the nozzle 184 is in contact with the outer circumferential surface of the roller 124 located above the pair of rollers 124, and the lower surface of the left side of the nozzle 184 is the pair of rollers. It comes in contact with the outer circumferential surface of the roller 124 located below in the 124.

In this case, the plane extending from the inner bottom surface of the injection hole 186 forms a plane including a tangent of the roller 124 located below the pair of rollers 124.

Therefore, since the height of the injection hole 186 is formed higher than the distance between the pair of rollers 124, as described above, the ceiling of the injection hole 186 is located above the lower end of the upper roller 124 do.

This concentrates the pressing force applied in the up / down direction of the molten metal by the pair of rollers 124 to the pressing force in the upward direction, thereby changing the solid-liquid interface of the plate P to form an asymmetric shape. This is to prevent cracks on the surface.

Referring to FIG. 4, which is attached to the configuration of another embodiment of the molten metal injection means 180, the appearance of the molten metal injection means 180 is substantially the same as that of the embodiment. However, the contact configuration of the roller 124 and the nozzle 184 is configured differently.

That is, in one embodiment, the line segment connecting the center of rotation of the pair of rollers 124 and the extension line of the nozzle 184 are coupled orthogonally, but in another embodiment, the line of rotation of the pair of rollers 124 is connected. The intersection angle A formed between the line segment and the extension line of the nozzle 184 is an acute angle or an obtuse angle.

More specifically, the shape of the molten metal injection means 180 is horizontal with respect to the ground as in the embodiment for storing and transporting the molten metal, but the pair of rollers 124 has a line segment connecting each center line. It is installed to be inclined with respect to the ground.

Therefore, since the outer surface of the nozzle 184 has a shape corresponding to the outer surface of the pair of rollers 124 in the inclined state, the upper and lower portions have an asymmetric shape with respect to the center.

In addition, the inner bottom surface of the injection hole 186 is positioned at the same height as the tangent to the roller 124 located below the pair of rollers 124.

Therefore, even if the roller 124 and the molten metal injection means 180 are configured in different embodiments, the solid-liquid interface of the molten metal pressed by the roller 124 may be formed asymmetrically.

Hereinafter will be described with reference to Figure 5 attached to the plate continuous casting method using a plate continuous casting apparatus configured as described above.

5 is a flowchart showing a plate continuous casting method using a plate continuous casting apparatus according to the present invention.

As shown in the drawing, the continuous plate casting method, the injection means installation step (S100) for installing a pair of rollers 124 and the nozzle 184 to contact each other, and provides a rotational power to the pair of rollers 124 Roller rotation step (S200) to rotate in different directions, and the molten metal supply step (S300) for supplying the molten metal into the molten metal injection means 180, and the molten metal supplied into the molten metal injection means 180 Melt injection step (S400) for injecting between the pair of rollers 124, melt coagulation step (S500) for pressing and solidifying the melt injected into the roller 124, and made by the melt coagulation step (S500) It consists of a plate withdrawal step (S600) for withdrawing the plate (P).

Looking specifically at this step by step, the injection means installation step (S100) is a process to make the inner bottom surface of the injection hole 186 coincides with the tangent of the lower roller 124, the injection means installation step (S100) is completed When the bottom surface of the molten metal injected into the roller 124 in the molten metal injection step (S400), the reduction ratio by the lower roller 124 can be minimized.

The molten metal supplying step (S300) is a process of supplying a molten metal produced by heating and melting the solid state material contained in the melting furnace 160 into the tundish 182.

The molten metal injection step (S400) is a process in which the molten metal supplied inside the tundish 182 moves along the nozzle 184 communicating with the tundish 182 and is supplied between the pair of rollers 124.

At this time, the bottom surface of the molten metal injected into the roller 124 through the injection hole 186 is placed on the same plane as the upper tangent of the lower roller 124 of the pair of rollers 124.

The molten solidification step (S500) is a process in which the molten metal injected into the roller 124 is thicker than the distance from which the pair of rollers 124 are spaced apart, and thus is pressed down into the roller 124.

At the same time, the cooling water passage 125 absorbs heat of the molten metal through the roller 124, so that the molten metal decreases in thickness and cools to form a plate P.

The plate taking out step (S600) is a process of drawing out the plate (P) formed by the molten solidification step (S500) may be stored in a state in which the plate (P) is wound in a separate storage roller (not shown) There will be.

As the above process proceeds sequentially, the molten metal can be continuously cast in the form of a plate.

Hereinafter, an embodiment according to the above method will be described with reference to FIGS. 6 to 9.

6 is a configuration diagram of an embodiment and a comparative example of a plate continuous casting method using a plate continuous casting apparatus according to the present invention, Figure 7 is a comparison picture showing the surface state of the plate manufactured using FIG.

8 is an experimental result showing a solid-liquid interface state when the rotational speed of the roller in the continuous plate casting apparatus according to the present invention, Figure 9 shows the amount of cooling water provided to the roller 124 in the continuous plate casting apparatus according to the present invention It is a photograph which shows the surface state of the board | plate material P at the time of a change.

EXAMPLE

An Al-5wt% Mg-0.3wt% Cu-0.02wt% Ti alloy was cast molded into a 80 mm wide plate.

The distance between the pair of rollers 124 is 3 mm.

First, when the upper open nozzle (Fig. 6 (a) is applied, non-uniformity of the molten metal supply occurs, surface defects due to shrinkage of the plate (P) as shown in Fig. 7 (a)).

Next, when the symmetrical nozzle (Fig. 6 (b)) is applied, the variation in the molten metal supply is reduced to remove the surface coagulation shrinkage defect of the sheet to some extent, but a minute crack occurred on the surface of the plate (P).

These cracks are cracks generated from the grain boundaries due to the load applied to the molten metal upon contact with the roller 124.

Finally, in the case of using the asymmetric nozzle 184 as shown in the embodiment of the present invention (FIG. 6 (c)), the molten metal first contacts with the surface of the upper roller 124 to start to solidify, so that the asymmetric solid-liquid interface is It is formed, and the amount of rolling reduction during the manufacture of the plate is relatively small, the pressure applied during casting is lowered. Accordingly, no crack was found on the surface of the plate P (see FIG. 7C).

Therefore, when the nozzle 184 and the injection hole 186 has an asymmetric shape of the upper and lower portions with respect to the center line between the rolls, it can be seen that the surface state of the manufactured plate material P is formed evenly.

Hereinafter, the solid-liquid interface and the shape of the surface of the plate P according to the change of the rotational speed of the roller 124 will be described with reference to FIG. 8.

As shown in the figure, the rotational speeds of the rollers 124 were divided into three types such as 3 rpm, 4 rpm, and 5 rpm, and the same experiment conditions were applied.

As shown in the figure, as the rotational speed of the roller 124 decreases from 5 rpm to 3 rpm, it can be seen that the solid-liquid interface is formed closer to the nozzle 184 without penetrating deeply between the rollers 124.

In another experiment, the cooling water amount condition of the cooling water passage 125 was changed in the state in which the rotation speed of the roller 124 was fixed at 5 rpm, and the result is shown in FIG. 9.

As shown in FIG. 9, the cooling water flow conditions of the cooling water passage 125 were changed to 120 L / min, 60 L / min, and 30 L / min, respectively, and the remaining experimental conditions were the same. It can be seen that the surface state of the plate (P) evenly appeared as the less from 30l / min in min.

The scope of the present invention is not limited to the above-exemplified embodiments, and many other modifications based on the present invention may be made by those skilled in the art within the above technical scope.

For example, in the embodiment of the present invention, the injection hole 186 is configured to have an asymmetrical shape in the up / down direction, but the pair of rollers 124 are different directions within a range capable of making the solid-liquid interface asymmetrical. And rotate at speed.

That is, even if the nozzle 184 and the injection hole 186 are formed to be symmetrical with respect to the center, and the bottom surface of the injection hole 186 is configured not to match the tangent of the roller 124, the pair of rollers 124 are It is apparent that the shape of the solid-liquid interface may be configured to have an asymmetrical shape at different speeds, more specifically, by allowing the roller located at the upper side to rotate at a faster rotational speed than the roller located at the lower side.

As described in detail above, in the continuous plate casting apparatus according to the present invention, the solid-liquid interface formed between a pair of rollers in continuous casting of aluminum and magnesium has an asymmetric shape, and at the same time, the solid-liquid interface is formed deep between the rollers. Is configured to be blocked.

Therefore, it is possible to block the instantaneous increase in the pressing force applied to the pair of rollers, thereby preventing the surface cracking of the thin plate, thereby improving the quality of the plate.

In addition, the present invention is configured such that the plate forming is completed only by the process of injecting and pressing the molten metal between the pair of rollers.

Therefore, the plate productivity is improved and there is an advantage that can lower the manufacturing cost of the plate.

Claims (9)

A rolling means provided with a pair of rotating rollers to pressurize the molten metal, Control means for controlling the operation of the rolling means; A melting furnace which heats the material to form a molten metal, It includes a molten metal injection means for receiving the molten metal from the melting furnace and injecting the molten metal into the rolling means, The molten metal injection means is a plate continuous casting apparatus characterized in that it is installed to have a different contact area to the roller located on the upper side and the lower roller of the pair of rollers. According to claim 1, wherein the molten metal injection means, A tundish for temporarily storing the molten metal, It comprises a nozzle for guiding the molten metal stored in the tundish to the rolling means, On one side of the nozzle, Perforated and formed, the inner bottom surface is formed in parallel with the tangent of the roller plate continuous casting apparatus, characterized in that the injection hole for guiding the moving direction of the molten metal to the rolling means. The method of claim 2, wherein the nozzle, Plate continuous casting device, characterized in that the cross-sectional shape of the upper and lower parts with respect to the center. The method of claim 3, wherein the end shape of the nozzle, Plate continuous casting apparatus, characterized in that corresponding to a part of the outer shape formed by the pair of rollers. The sheet continuous casting apparatus as claimed in claim 2, wherein the extension line of the nozzle forms an acute angle or an obtuse angle with a line segment following the rotation center of the pair of rollers. A rolling means provided with a pair of rotating rollers to pressurize the molten metal, Control means for controlling the operation of the rolling means; A melting furnace which heats the material to form a molten metal, It includes a molten metal injection means for receiving the molten metal from the melting furnace and injecting the molten metal into the rolling means, The pair of rollers is a continuous plate casting apparatus characterized in that to form a liquid-liquid interface of the asymmetrical shape by rotating at different rotational speeds. An injection means installation step of installing a pair of rollers and asymmetrical nozzles for guiding the molten metal from one side of the molten metal injection means to be in contact with each other; A roller rotation step of providing rotational power to the pair of rollers to rotate in different directions; A molten metal supplying step of supplying a molten metal into the molten metal injection means; A molten metal injection step of injecting the molten metal supplied to the molten metal injection means between a pair of rollers; A molten metal solidifying step in which the molten metal injected between the pair of rollers is pressed and solidified; A plate continuous casting method using a plate continuous casting device, characterized in that consisting of a plate withdrawing step for withdrawing the plate formed by the pair of rollers solidified. The method of claim 7, wherein the injection means installation step, A plate continuous casting method using a plate continuous casting device, characterized in that the inner bottom surface of the injection hole provided in the nozzle to match the roller tangent of the lower side. The method of claim 7, wherein the roller rotating step, Plate continuous casting method using a plate continuous casting device characterized in that the process of rotating the pair of rollers at different rotational speeds.

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