JPH11207442A - Mold in continuous casting equipment and casting method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold which obtains the optimum cooling pattern according to various kinds of steel in one mold, and a casting method using this mold. SOLUTION: A cooling water passage 10 formed in the vertical direction in the cross section of copper plate 5 constituting the mold in a continuous casting equipment, is constituted of an upper cooling water passage 10a near the upper part of the mold and a lower cooling water passage 10b at the lower part from the neighborhood of the upper part of the mold. The distance of the upper cooling water passage 10a from the copper plate surface 5a is made further than the distance of the lower cooling water passage 10b from the copper plate surface 5a, and the cross sectional area of the upper cooling passage 10a is made larger than the cross sectional area of the lower cooling passage 10b so as to slowly cool the upper part of the mold and intensely cool the lower part of the mold. Therefore, the combination of the slow cooling and the intense cooling, or the intense cooling to the whole mold can freely be selected by vertically displacing the molten metal surface level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for a continuous casting facility and a casting method using the same. It is known that the slab quality when steel is continuously cast is greatly affected by the strength of cooling by a mold. In order to prevent the surface flaw of the slab and improve the casting speed, the cooling strength may be changed depending on the type of steel. The present invention relates to a mold and a casting method suitable for such purpose.

[0002]

2. Description of the Related Art To change the cooling strength depending on the type of steel,
This is possible if the mold is changed for each type of steel, but this is very poor in productivity. However, productivity can be improved if one mold can realize an optimal cooling method corresponding to various steel types.
As such a conventional technique, there is a technique described in Japanese Utility Model Publication No. 5-30839.

[0003] This prior art will be described with reference to FIG. 5
Reference numeral 2 denotes a copper plate having through-holes 53 vertically formed in the cross section thereof,
The rod 58 is inserted into the inside thereof, and the through hole 53 and the rod 5 are inserted.
8, a cooling water passage 54 is formed. This stick 58
The diameter of the central part is larger than that of the upper and lower ends, and the flow rate of the cooling water is lower at the lower part of the cooling water passage 54, faster at the central part, and slower at the upper part. Therefore, since the flow rate of the cooling water is high at the central part in the vertical direction of the mold, the central part is large in view of the cooling effect of only the copper plate.

[0004]

However, the above-mentioned prior art has made the cooling effect of the central portion larger than that of the upper and lower portions by the above configuration because the electromagnetic stirring device 51 is provided at the central portion, so that the central portion has a high temperature. This is because this portion tends to be hardly cooled, so that a uniform cooling effect can be obtained as a whole. Therefore, the strength of cooling cannot be changed depending on the type of steel by using this mold.

[0005] In view of such circumstances, an object of the present invention is to provide a mold in which an optimum cooling pattern corresponding to various steel types can be obtained by one mold, and a casting method using the same.

[0006]

According to a first aspect of the present invention, there is provided a mold, wherein a cooling water passage formed vertically in a cross section of a copper plate constituting a mold of a continuous casting facility is formed from an upper cooling water passage near an upper portion of the mold and an upper portion near the upper portion of the mold. The lower cooling channel is composed of a lower cooling channel, the distance from the copper plate surface of the upper cooling channel is longer than the distance from the copper plate surface of the lower cooling channel, and the cross-sectional area of the upper cooling channel is larger than the cross-sectional area of the lower cooling channel. It is characterized by the following. In the mold of claim 2, a cooling water passage is formed between the inner surface of the slit and the inner surface of the spacer by a slit cut from the back side of the copper plate and a spacer inserted into the slit from the back side. Forming the upper inner surface of the slit and the upper inner surface of the spacer at a position far from the surface of the copper plate, and increasing the distance between the upper inner surfaces, to reduce the lower inner surface of the slit and the lower inner surface of the spacer. It is characterized in that it is formed at a position close to the surface of the copper plate and the distance between both lower surfaces is reduced. The mold according to claim 3 forms a lower cooling water passage between the lower portion of the through hole and the spacer by forming a through hole in the copper plate in a vertical direction and inserting a rod-shaped spacer below the through hole. The cross-sectional area of the upper cooling water passage in the upper through hole where the spacer is not inserted is larger than the cross-sectional area of the lower cooling water passage between the lower through hole and the spacer, and the upper cooling water passage is a copper plate of the lower cooling water passage. It is characterized by being farther from the surface of the copper plate than a portion closer to the surface. The casting method according to claim 4 uses the mold according to claim 1, 2 or 3 to slowly cool the upper part of the mold and to strongly cool the lower part of the mold. It is characterized in that the molten steel in the mold can be selected from cooling by a combination of slow cooling and strong cooling, or cooling only by strong cooling, by changing the temperature of the molten steel in the mold up and down below the upper part of the mold.

According to the first aspect of the present invention, since the upper cooling channel is located far from the copper plate surface and has a large cross-sectional area, the flow rate of the cooling water is slow, so that the cooling effect is weak, and the lower cooling channel is cut close to the copper plate surface. Since the area is small, the flow rate of the cooling water is high, so that the cooling effect is high. Therefore, the vicinity of the upper part of the mold is cooled slowly, and the part below the upper part of the mold can be cooled strongly. According to the second aspect of the present invention, the distance and the sectional area of the upper cooling water channel and the lower cooling water channel from the surface of the copper plate are configured by the spacer and the slit.
In the same manner as in the invention described above, the vicinity of the upper part of the mold can be slowly cooled and the part below the upper part of the mold can be strongly cooled. In the invention of claim 3,
The through holes and the spacers define the distance and cross-sectional area of the upper cooling water channel and the lower cooling water channel from the surface of the copper plate. With this configuration, the vicinity of the upper part of the mold is slowly cooled as in the first aspect of the present invention. The lower part can be strongly cooled.
According to the invention of claim 4, by raising and lowering the level of the molten metal in the mold, casting combining slow cooling of the upper part of the mold and strong cooling below the upper part of the mold and casting of strongly cooling the entire mold copper plate can be performed. Yes, a cooling pattern suitable for each of low carbon steel, medium carbon steel and high carbon steel can be selected, so that high quality steel can be cast in one mold.

[0008]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a cross-sectional view of a mold copper plate according to an embodiment of the present invention, and FIG.
FIG. 2A is a cross-sectional view of a mold copper plate according to an embodiment of the present invention, FIG. 2B is a cross-sectional view of FIG. Item 2 is a sectional view of a mold copper plate according to another embodiment of the invention, and FIG. 4 is a perspective view of the mold.

First, the basic structure of the mold will be described with reference to FIG. Reference numerals 1 and 2 denote long side frames, and short side frames 3 and 4 are sandwiched between the long side frames 1 and 2. A copper plate 5 is adhered to the inner surface of each of the frames 1 to 4, and this copper plate 5 constitutes a mold. Each of the frames 1 to 4 is a water box, in which water is supplied from a lower water supply pipe 6, drained from an upper water supply pipe 7, and cooling water is constantly circulated to cool the copper plate 5.

Next, an embodiment of the present invention will be described with reference to FIG. 5 is a mold copper plate, and S is molten steel. The meniscus, which is the upper surface of the molten steel S, is in a state near the upper part of the normally cast mold. A slit 11 is cut from the back side of the copper plate 5, and a spacer 12 is inserted into the slit 11, and a cooling water passage 10 is formed between the slit 11 and the spacer 12. The vertical height of the spacer 12 is the same as that of the slit 1.
1, a lower inlet 13 and an upper outlet 14 are provided at a lower end and an upper end of the cooling water passage 10, respectively.

In the vicinity of the upper part of the mold of the slit 11, the copper plate surface 5
The lower part is located farther from the copper plate surface 5a, and the lower part is inclined and connected in the middle. The spacer 12
The upper part is far away from the copper plate surface 5a, and the lower part is the copper plate surface 5a.
It is located close to "a" and is connected at an angle in the middle. As a result, the distance D of the upper cooling water passage 10a from the copper plate surface 5a is increased.
1 is a distance D2 from the copper plate surface 5a of the lower cooling water passage 10b.
Since it is larger, the cooling capacity of the upper cooling channel 10a is lower than that of the lower cooling channel 10b.

A sectional area A defined by the upper inner surface 11a of the slit 11 and the upper inner surface 12a of the spacer 12
1 is wider than the cross-sectional area A2 defined by the lower inner surface 11b of the slit 11 and the lower inner surface 12b of the spacer 12. For this reason, the flow rate of the cooling water in the lower cooling water passage 10b is higher than that in the upper cooling water passage 10a, so that the cooling capacity of the upper cooling water passage 10a is lower than that of the lower cooling water passage 10b.

In short, the upper cooling water passage 10a is formed on the copper plate surface 5a.
The cooling capacity is lower than that of the lower cooling water passage 10b depending on the distance from the lower cooling water passage 10b.
Has a higher cooling capacity than the upper cooling channel 10a. For this reason, the upper part of the mold copper plate is slowly cooled, and the part below the upper part of the mold copper plate is strongly cooled.

Next, a casting method using the above mold will be described. In the mold of FIG. 1, the vicinity of the upper portion of the mold is slowly cooled, and the portion below the upper portion of the mold is strongly cooled. Therefore, if the molten steel level is maintained at the upper part of the mold, the upper molten steel in the mold will be slowly cooled and the lower molten steel will be strongly cooled. On the other hand, when the level of the molten metal is lowered, the molten steel in the mold is strongly cooled as a whole.

Therefore, for example, moderate cooling near the upper part of the mold is effective to prevent surface defects of medium carbon steel, while increasing the casting speed requires lowering the lower part of the mold to secure the solidified shell thickness of the slab. Must be strongly cooled. Therefore, in this case, if casting is performed while maintaining the molten metal level above the mold, moderate cooling is performed above the mold and strong cooling is performed below the mold, so that medium carbon steel can be cast at high speed without surface defects. In addition, low-carbon steel and high-carbon steel require strong cooling of the entire mold copper plate. In this case, the lower cooling water passage 10a
When the operation is performed with the level of the molten metal lowered to a position facing the surface, the entire mold copper plate is strongly cooled, so that high-quality casting of low-carbon steel or high-carbon steel becomes possible.

Next, an embodiment of the present invention will be described with reference to FIG. In the cross section of the copper plate 5, through holes 21 are formed vertically.
Is that the lower section A3 is larger than the upper section A1,
The hole is concentric through the top and bottom. Through hole 21 with large cross section
A rod-shaped spacer 22 is coaxially inserted in the lower part of the frame. As a result, a lower cooling water passage 10b is formed between the outer periphery of the spacer 22 and the through hole 21. The inside of the upper through hole 21 having a small cross section is an upper cooling water passage 10a. In the lower cooling water passage 10b, a cross section A2 obtained by subtracting the cross section A4 of the rod-shaped spacer 22 from the cross section A3 is a true flow passage cross-sectional area of the lower cooling water passage 10b. The lower section A2 is smaller than the upper section A1. For this reason, the cooling capacity is higher at the lower portion where the flow rate of the cooling water is higher. Further, the distance D1 from the copper plate surface 5a of the upper cooling water passage 10a.
Is longer than the distance D2 from the copper plate surface side around the spacer 22 in the lower cooling water passage 10b to the copper plate surface 5a.

In short, the upper cooling water passage 10a is formed on the copper plate surface 5a.
The cooling capacity is lower than that of the lower cooling water passage 10b due to the distance from the lower cooling water passage 10b.
Has a higher cooling capacity than the upper cooling channel 10a. For this reason, the upper part of the mold copper plate is slowly cooled, and the part below the upper part of the mold copper plate is strongly cooled.

Next, a casting method using the above mold will be described. In the mold of FIG. 2, the vicinity of the upper part of the mold is slowly cooled, and the vicinity of the lower part of the mold is strongly cooled. Therefore, when the molten steel surface level is maintained at the upper part of the mold, the upper part is slowly cooled and the lower part is strongly cooled. On the other hand, when the level of the molten metal is lowered, the whole is strongly cooled.

Therefore, for example, in order to prevent surface defects of medium carbon steel, gentle cooling near the meniscus is effective.
In order to increase the casting speed, the lower part of the mold must be strongly cooled to secure the solidified shell thickness of the slab. Therefore, in this case, if casting is performed while maintaining the molten metal level above the mold, moderate cooling is performed above the mold and strong cooling is performed below the mold, so that medium carbon steel can be cast at high speed without surface defects. Further, in order to cast low-carbon steel at a higher speed, it is necessary to strongly cool the entire mold copper plate. In this case, when the operation is performed with the molten metal level lowered to the position facing the lower cooling water passage 10a, the entire mold copper plate is strongly cooled, so that the temperature rise of the mold can be suppressed.

Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, the lower part of the through hole 31 formed in the up-down direction is provided in parallel with the copper plate surface 5a, and the upper part approaches the upper end to the copper plate surface 5a.
The rod-shaped spacer 32 is inserted into the through hole 31 in the lower part. As a result of the above configuration, the cross-sectional area of the lower cooling water passage 10b is smaller than the cross-sectional area of the upper cooling water passage 10a. Also,
The upper cooling water passage 10a is farther from the copper plate surface 5a as it goes from the connection with the lower cooling water passage 10b to the upper end. In this embodiment, as in the embodiment of FIG. 2, when the molten steel surface level is maintained at the upper part of the mold, the upper part is slowly cooled and the lower part is strongly cooled. on the other hand,
When the level of the molten metal is lowered, the whole is strongly cooled.

[0021]

According to the first aspect of the present invention, the upper cooling channel is located far from the surface of the copper plate and has a large cross-sectional area, so that the cooling water flow rate is low, so that the cooling effect is weak. Since the cross-sectional area is small and the flow rate of the cooling water is high, the cooling effect is high. Therefore, the vicinity of the upper part of the mold is cooled slowly, and the part below the upper part of the mold can be cooled strongly. According to the second aspect of the present invention, the distance and the sectional area of the upper cooling water channel and the lower cooling water channel from the surface of the copper plate are configured by the spacer and the slit. It is possible to cool and strongly cool below the upper part of the mold. According to the third aspect of the present invention, the through holes and the spacers define the distance and the cross-sectional area of the upper cooling water passage and the lower cooling water passage from the copper plate surface,
With this configuration, it is possible to slowly cool the vicinity of the upper part of the mold and to strongly cool the lower part of the upper part of the mold as in the first aspect of the invention. According to the invention of claim 4, by raising and lowering the level of the molten metal in the mold, casting combining slow cooling of the upper part of the mold and strong cooling below the upper part of the mold and casting of strongly cooling the entire mold copper plate can be performed. Yes, a cooling pattern suitable for each of low carbon steel, medium carbon steel and high carbon steel can be selected, so that high quality steel can be cast in one mold.

[Brief description of the drawings]

1A is a cross-sectional view of a mold copper plate according to an embodiment of the first aspect of the present invention, and FIG. 1B is a cross-sectional view of FIG.

2A is a cross-sectional view of a mold copper plate according to an embodiment of the second aspect of the present invention, and FIG. 2B is a cross-sectional view of FIG.

FIG. 3 is a sectional view of a mold copper plate according to another embodiment of the invention of claim 2;

FIG. 4 is a perspective view of a mold according to the present invention.

FIG. 5 is a sectional view of a conventional mold copper plate.

[Explanation of symbols]

 5 Copper plate 10 Cooling water channel 10a Upper cooling water channel 10b Lower cooling water channel 11 Slit 12 Spacer 21 Through hole 22 Spacer 31 Through hole 32 Spacer

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Murakami 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd.

Claims (4)

[Claims] 1. A cooling water passage formed vertically in a cross section of a copper plate constituting a mold of a continuous casting facility comprises an upper cooling water passage near an upper portion of a mold and a lower cooling water passage below a portion near an upper portion of the mold. A mold for continuous casting equipment, wherein the distance of the cooling channel from the copper plate surface is longer than the distance of the lower cooling channel from the copper plate surface, and the cross-sectional area of the upper cooling channel is larger than the cross-sectional area of the lower cooling channel. 2. A cooling water passage is formed between the inner surface of the slit and the inner surface of the spacer by a slit cut from the back surface of the copper plate and a spacer inserted into the slit from the back surface. The upper inner surface of the slit and the upper inner surface of the spacer are formed at positions far from the surface of the copper plate, and the distance between both upper inner surfaces is increased, so that the lower inner surface of the slit and the lower inner surface of the spacer are formed on the copper plate surface. 2. A mold for a continuous casting facility according to claim 1, wherein the mold is formed at a position close to the lower surface and a distance between both lower surfaces is reduced. 3. A through-hole is formed vertically in said copper plate,
A lower cooling channel is formed between the lower portion of the through hole and the spacer by inserting a rod-shaped spacer below the through hole, and a cross-sectional area of the upper cooling channel in the upper through hole in which the spacer is not inserted. Is larger than the cross-sectional area of the lower cooling channel between the lower through hole and the spacer, and the upper cooling channel is farther from the copper plate surface than the portion of the lower cooling channel near the copper plate surface. The mold of the continuous casting facility as described. 4. The method according to claim 1, 2 or 3,
Slowly cool the top of the mold, and strongly cool the bottom of the mold,
Depending on the type of steel, the level of the molten metal in the mold is changed up and down between near the upper part of the mold and below the upper part of the mold, so that the molten steel in the mold can be cooled by a combination of slow cooling and strong cooling, or cooled only by strong cooling. A casting method characterized in that: