JP2010221237A - Cast slab supporting device directly below mold of continuous casting machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cast slab supporting device directly below the mold of a continuous casting machine, which has a high supporting area ratio, has excellent effect for prevention of bulging of a cast slab, also, is safely operable, without causing steam exposure even in the case breakout occurs. <P>SOLUTION: In the cast slab supporting device directly below the mold of a continuous casting machine installed directly below the mold of the continuous casting machine, a through-hole-fitted plate 2 having many through-holes 2a or a network plate having network opening parts is arranged as a guide plate 1 at a position in contact with a cast slab 7 over the whole region in the width direction of the long side face of the cast slab, and further, a spray nozzle for spraying cooling water toward the long side face of the cast slab and the guide plate is arranged at a position separated on the back face side of the guide plate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a slab support device directly under a continuous casting machine mold for supporting and cooling a slab continuously drawn out from a mold of a continuous casting machine.

  In continuous casting of steel, molten steel poured from a ladle into a tundish is poured into a water-cooled mold through an immersion nozzle installed at the bottom of the tundish, and then the solidified shell formed by the mold is removed. The cast slab as a shell is continuously drawn below the mold while being cooled, and a continuous cast slab is manufactured.

  In recent years, in order to reduce the manufacturing cost, there has been an increasing demand for improvement in productivity, and in the continuous casting process, the speed of the production line, that is, the drawing speed of the slab is increased. In order to realize this high drawing speed, it is necessary to solve various problems. In particular, a technique for more efficiently supporting and cooling the slab directly under the mold is required. Under high-speed casting, the thickness of the solidified shell immediately below the mold becomes thin, and this solidified shell breaks and breaks out, or the solidified shell does not break. Due to the pressure, bulging occurs, and the molten steel surface in the mold fluctuates up and down, and mold powder is caught in the solidified shell, resulting in problems such as quality defects. That is, there is a demand for a method for efficiently cooling a slab immediately below the mold while supporting the slab so that bulging does not occur.

  Conventionally, methods for supporting and cooling a slab directly under a mold are roughly divided into (1) a roll method, (2) a cooling grid method (see, for example, Patent Document 1), and (3) a cooling plate method ( For example, the following three methods have been put into practical use (see Patent Document 2).

  Needless to say, the roll method is similar to the middle and downstream sides of the continuous casting machine, and opposed slab support rolls are arranged side by side in the casting direction, and a spray nozzle is placed in the gap between adjacent rolls in the casting direction. Is installed, and the slab is supported by opposing rolls while the slab is cooled by spray water sprayed from a spray nozzle.

  The cooling grid system is composed of a wear plate 9 for supporting the slab 7 and a spray nozzle 4 installed in a gap between the wear plate 9 as shown in a schematic perspective view of FIG. A plurality of wear plates 9 arranged in a staggered manner support the slab 7 and directly cool the slab 7 with spray water 5 sprayed from a number of spray nozzles 4. Such a combination of a large number of wear plates 9 and spray nozzles 4 is referred to as a cooling grid facility 8. The wear plate 9 is cooled by the spray water 5 sprayed from the spray nozzle 4, and the portion of the slab 7 that contacts the wear plate 9 is indirectly cooled.

  Further, in the cooling plate method, as shown in FIG. 5, a schematic perspective view of the cooling plate to be used is formed with a large number of concavities 11 for injection which are recessed conically on the surface on the contact surface side with the slab. This is a device that supports the entire width of the slab directly below the mold by a cooling plate 10 in which an injection hole 12 for injecting cooling water from the back side toward the slab is formed at the center of the injection recess 11. The cooling plate 10 is cooled by cooling water flowing through the inside thereof, and the cooling plate 10 itself is also configured to indirectly cool the slab. That is, the entire width direction of the slab is supported by one cooling plate 10, and the slab is indirectly cooled by the cooling plate 10, and the slab is directly cooled by the cooling water sprayed from the injection holes 12. It is the apparatus comprised as follows.

JP 2008-238201 A Japanese Unexamined Patent Publication No. 57-25268

  However, the conventional slab support device directly under the mold has the following problems.

  That is, in the roll method, the slab can be cooled uniformly over the entire width direction, but since the slab is supported by a roll, that is, by a wire, the slab of the slab is compared with the other two methods that support the surface. There is a basic problem that the support area is small and the slab is easy to bulge.

  In the cooling grid method, the support area ratio of the slab is at most about 50%, and it is desirable to further increase the support area ratio of the slab under high speed casting. In addition, the part that comes into contact with the wear plate is indirectly cooled, and the cooling difference with the direct cooling part by spray water is large, resulting in temperature unevenness in the slab surface temperature and causing surface cracks in the slab. There is also a problem.

  In the cooling plate method, the entire width direction of the slab is supported by a single large plate, which has a high support area ratio and is very effective in preventing bulging of the slab. Depending on the contact condition, the water sprayed from the plate surface may cause a situation where there is no escape from the steam generated after the slab is cooled. There are also safety issues. Further, since the plate is large and has an integral structure, it is difficult to process and repair.

  The present invention has been made in view of the above circumstances, and its purpose is to eliminate the problems of the conventional cooling plate method, thereby providing a high support area ratio and an excellent effect in preventing bulging of the slab. It is an object of the present invention to provide a slab support device directly under a mold of a continuous casting machine that can be operated safely without causing a steam explosion even when a breakout occurs.

  A slab support device directly under a mold of a continuous casting machine according to a first aspect of the present invention for solving the above-mentioned problem is a slab support device installed directly under a mold of a continuous casting machine and having a plurality of through holes. A perforated plate or a mesh-like plate having a mesh-like opening is arranged as a guide plate at a position in contact with the slab over the entire width direction of the slab long side surface, and is separated from the back side of the guide plate. A spray nozzle for injecting cooling water toward the long side surface of the slab and the guide plate is disposed at the position.

  According to a second aspect of the present invention, there is provided a slab support device immediately below a continuous casting machine mold, wherein the guide plate is configured to be divided into a plurality of portions.

  According to the present invention, since the entire long side surface of the slab is supported by the guide plate, it is possible to prevent bulging of the slab, and through a through-hole or a mesh-like opening provided in the guide plate. Since the cooling water from the spray nozzle is sprayed onto the surface of the slab, there is no place where the cooling water is accumulated, and even if a slab breakout occurs, it is possible to prevent a steam explosion originating from the slab support device. . Furthermore, depending on the installation method of the through hole and the mesh opening, when the through hole and the mesh opening are arranged finely dispersed, the positions where the spray water hits are finely dispersed, that is, the spray water. The direct cooling location due to and the indirect cooling location due to the guide plate are finely dispersed, and cooling unevenness of the slab can be suppressed. As a result, it is possible to increase the slab drawing speed while maintaining the quality of the slab, and a stable improvement in productivity is realized.

It is a schematic perspective view of the slab continuous casting machine provided with the slab support apparatus which concerns on this invention. It is sectional drawing which looked at the slab support apparatus which concerns on this invention from the short side surface side of the slab. It is the schematic of the mesh shaped plate which is another example of a guide plate of the slab support apparatus which concerns on this invention. It is a schematic perspective view of the conventional cooling grid system. It is a schematic perspective view of the plate used with the conventional cooling plate system.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic perspective view of a slab continuous casting machine provided with a slab support device according to the present invention, and FIG. 2 is a cross-sectional view of the slab support device according to the present invention as viewed from the short side surface side. is there.

  As shown in FIG. 1, a plate with a through hole having a large number of through holes 2 a at a position in contact with the slab 7 directly across the entire width direction of the long side surface of the slab 7 immediately below the mold 6 of the slab continuous casting machine. 2 is arranged as the guide plate 1 of the slab 7. The through holes 2 a are arranged side by side in the width direction of the slab 7, and are so-called “staggered arrangement” in which the upstream side and the downstream side are alternately arranged in each stage in the casting direction. In FIG. 1, only one plate 2 with a through hole is shown on one side, but the plate 2 with a through hole is also arranged on the opposite side of the cast piece 7.

  The plate 2 with a through hole is preferably made of cast iron or cast steel because it is excellent in thermal shock due to its material, and may be an integral structure type or a split type that can be divided into a plurality of parts. Either of them may be used, but it is preferable to use a split type because it is easy to process and repair. Moreover, the plate width direction length is set so that the plate 2 with a through-hole can support the full width of the slab 7 of the maximum width cast with each slab continuous casting machine.

  On the other hand, the length in the casting direction of the plate 2 with the through hole does not need to be particularly specified, and may be an appropriate length. However, from the viewpoint of ensuring slab support directly under the mold, the length may be 500 mm or more. preferable. The maximum length may be about 2000 mm. Since the thickness of the solidified shell grows and becomes thick in the range of 2000 mm and beyond, it can be sufficiently supported by the conventional roll method. Moreover, the thickness of the plate 2 with a through-hole should just have sufficient intensity | strength to support the slab 7, and generally 30-50 mm is enough.

  Then, as shown in FIG. 2, the plate 2 with through-holes and the slab 7 are separated from the back side of the plate 2 with through-holes configured as the guide plate 1 in this way, that is, on the side opposite to the slab side. The spray nozzle 4 for injecting the spray water 5 toward the long side surface is arranged. The spray water 5 from the spray nozzle 4 directly collides with the long side surface of the slab 7 through the through-hole 2a at the position where the through-hole 2a is installed, and cools the slab 7; The plate 2 with a through hole is cooled by colliding with the plate 2 with a through hole. That is, the portion of the slab 7 that comes into contact with the plate 2 with a through hole is configured to be indirectly cooled by the plate 2 with a through hole.

  In this case, the spray nozzle 4 is arranged so that the spray water 5 is sprayed over the entire region in the width direction and the casting direction of the plate 2 with through holes. Moreover, it is preferable that the distance of the front-end | tip position of the spray nozzle 4 and the long side surface of the slab 7 shall be 50-250 mm. If this distance is less than 50 mm, the spread angle of the spray water 5 is limited, so that a large number of spray nozzles 4 must be arranged, which is not economical, and the cooling water from the slab 7 bounces, Cooling may not be performed as prescribed. On the other hand, when the distance exceeds 250 mm, the nozzle interval is increased, and the water density density distribution of the spray water 5 on the spray surface becomes uneven or insufficient, that is, the cooling becomes uneven or insufficient. This is not preferable. The spray nozzle 4 shown in FIG. 2 is a water spray nozzle that ejects only cooling water, but may be an air mist spray nozzle that mixes and sprays air and cooling water.

  Although the plate 2 with the through hole is cooled by the spray water 5, in order to further strengthen the indirect cooling of the slab 7 by the plate 2 with the through hole, the flow of the cooling water is introduced into the plate 2 with the through hole. A path may be provided to provide a water cooling structure. Moreover, it is preferable to arrange the through-hole plate 2 as the guide plate 1 on the short side surface side of the slab 7, but in general, the slab continuous casting machine can change the slab width during casting. When the guide plate 1 is arranged on the short side surface side of the slab 7, it is necessary to change the installation position of the short side guide plate 1 in conjunction with the change of the slab width. Since the apparatus is complicated, the slab short side is often not installed. Originally, the bulging amount is small on the short side of the slab due to the influence of the slab corner, and this is one of the reasons that the guide plate 1 does not have to be installed on the short side of the slab. Needless to say, it is better to install on the short side as well.

  The support area ratio of the slab 7 by the plate 2 with a through hole depends on the area ratio of the through hole 2a in the plate 2 with the through hole. In this case, even if the large through holes 2a are arranged with a small number of installations and the small through holes 2a are arranged with a large number of installations, as long as the total area of the through holes 2a is the same, the slab 7 is supported. The area ratio is the same. However, from the viewpoint of uniform cooling of the slab 7, it is extremely important to reduce the temperature unevenness, and from the viewpoint of reducing the temperature unevenness, it is preferable to reduce the through holes 2a as much as possible and increase the number of installations. . Moreover, it is preferable that the support area ratio of the slab 7 exceeds 50%, that is, the area ratio of the through holes 2a in the plate 2 with through holes is less than 50%. In addition, although the through-hole 2a is circular in FIG. 1, various shapes, such as an ellipse and a polygon, may be sufficient.

  In the slab support device according to the present invention, the guide plate 1 is not limited to the plate 2 with a through hole, and may have a mesh-like opening. FIG. 3 shows a mesh plate having a mesh opening as another example of the guide plate 1.

  As shown in FIG. 3, the mesh plate 3 has lattice-like mesh openings 3 a regularly arranged in the width direction and the casting direction of the slab 7. The guide plate 1 is disposed at a position in contact with the slab 7 over the entire width direction of the long side surface of the slab 7. The spray water 5 sprayed from the spray nozzle 4 disposed at a separated position on the back side of the mesh plate 3 collides with the slab 7 through the mesh opening 3a, cools the slab 7, A portion of the slab 7 that contacts the mesh plate 3 is indirectly cooled by the mesh plate 3. What is necessary is just to perform the material of the mesh-shaped plate 3, a dimension, a structure, an installation position, a slab support area rate etc. according to the plate 2 with a through-hole mentioned above.

  As described above, according to the present invention, since the entire long side surface of the slab is supported by the guide plate 1, bulging of the slab 7 can be prevented, and the through-hole provided in the guide plate 1 can be prevented. Since the cooling water from the spray nozzle 4 is sprayed onto the surface of the slab through the opening 2a or the mesh-shaped opening 3a, there is no place where the cooling water is accumulated, and even if a breakout of the slab 7 occurs, the slab It is possible to prevent a steam explosion originating from the support device.

DESCRIPTION OF SYMBOLS 1 Guide plate 2 Plate with a through-hole 2a Through-hole 3 Reticulated plate 3a Opening part 4 Spray nozzle 5 Spray water 6 Mold 7 Cast piece 8 Cooling grid equipment 9 Wear plate 10 Cooling plate 11 Injecting hollow part 12 Injection hole

Claims (2)

  A slab support device installed directly under a mold of a continuous casting machine, wherein a plate with a through hole having a large number of through holes or a mesh plate having a mesh-like opening extends over the entire width direction of the long side of the slab. The guide plate is arranged at a position in contact with the slab, and a spray nozzle for injecting cooling water toward the long side surface of the slab and the guide plate is arranged at a separated position on the back side of the guide plate. A slab support device directly under a mold of a continuous casting machine.   The slab support device directly under a continuous casting machine mold according to claim 1, wherein the guide plate is configured to be divided into a plurality of parts.

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