Title of the invention: Scum suction member, double roll type continuous casting device, and method for manufacturing slabs
Technical field
[0001]
　The present invention relates to a scum suction member, a twin-roll type continuous casting apparatus using the scum suction member, and a method for manufacturing a slab.
Background technology
[0002]
　Double-roll continuous casting with a water-cooled structure inside and a pair of cooling rolls that rotate in opposite directions in order to manufacture thin-walled metal slabs (hereinafter sometimes referred to as cast strips). Equipment is provided. In such a twin-roll type continuous casting apparatus, molten metal is supplied to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side weirs, and is formed and grown on the peripheral surfaces of the pair of cooling rolls. The solidified shells are crimped to each other at a roll kiss point to produce a slab having a predetermined thickness. Such a double roll type continuous casting apparatus is applied to various metals.
[0003]
　Here, in the above-mentioned molten metal pool portion, oxides and the like float on the molten metal surface of the molten metal pool portion to form a film-like foreign substance called a scum, and this scum is intermittent on the peripheral surface of the cooling roll. There was a risk of getting caught in the pool. The entrained scum causes surface defects such as surface cracks and surface defects of the slab.
　Therefore, when casting a slab using the above-mentioned double-roll type continuous casting apparatus, the following techniques have been proposed as a method for suppressing the occurrence of surface defects by removing scum and detoxifying the slab. ..
[0004]
　For example, Patent Document 1 proposes that a solid oxide is arranged at the interface between the molten metal and the gas phase in the molten metal pool portion to capture the scum to prevent the scum from being involved in the solidified shell. ..
　Further, Patent Document 2 proposes a means for flushing the scum generated by the blowing of the inert gas to the vicinity of the side weir to prevent the scum from being taken in between the cooling roll and the solidification shell.
　Further, Patent Document 3 proposes a means for preventing the scum from being taken in between the cooling roll and the solidification shell by pushing the scum near the side weir by utilizing the discharge flow from the immersion nozzle.
[0005]
　In Patent Document 4, a pair of scum weirs are installed along the cooling roll width direction of the molten metal pool portion to relax the flow of the molten metal discharged from the immersion nozzle, thereby preventing the molten metal from rippling. , A method has been proposed to prevent the scum from being taken into the solidified shell by controlling the flow of the molten metal.
　Further, Patent Document 5 proposes a method in which the scum weir is made of a material having poor wettability with the scum to suppress the adhesion of the scum to the scum weir and maintain the effect of flow control for a long period of time. Has been done.
　Further, Patent Document 6 proposes the use of a scum weir having high heat resistance and impact resistance, which is a cheaper material and can withstand use in a state close to no preheating.
[0006]
　Patent Document 7 proposes a scum weir made of a material containing an element that increases the surface tension of a molten metal. By dissolving the element that increases the surface tension into the molten metal, it is possible to suppress the adhesion of scum to the scum weir.
　Further, Patent Document 8 proposes a scum weir made of Al 2 O 3, and by adsorbing the scum by the scum weir, the scum is prevented from being entrained in the thin-walled slab.
Prior art literature
Patent documents
[0007]
Patent Document 1: Japanese Patent Application Laid-Open No. 2002-273551
Patent Document 2: Japanese Patent Application Laid-Open No. 04-197560
Patent Document 3: Japanese Patent Application Laid-Open No. 06-339754
Patent Document 4: Japanese Patent Application Laid-Open No. 08-155593 JP
Patent Document 5: Japanese Unexamined Japanese Patent Application Laid-Open No. 07-214248
Patent Document 6: Japanese Patent 2003-039139 JP
Patent Document 7: Japanese Patent 2003-266154 JP
Patent Document 8: Japanese Patent No. 03 -066450A
Outline of the invention
Problems to be solved by the invention
[0008]
　Here, the method disclosed in Patent Document 1 has a problem that it becomes difficult to detect the molten metal level because the solid oxide covers the molten metal surface of the molten metal. Further, when the solid oxide and the cooling roll are arranged close to each other, there is a high concern that the scum grown by adhering to the solid oxide comes into contact with the cooling roll, and the scum may be trapped in the thin-walled slab. It was.
　Further, in the methods disclosed in Patent Documents 2 and 3, when the total amount of scum increases as the casting time increases, it becomes difficult to keep the scum only in the vicinity of the side weir, and the occurrence of surface defects can be prevented. There was a problem that the effect was reduced.
[0009]
　Further, the methods disclosed in Patent Documents 4, 5 and 6 cannot prevent entrainment in the solidified shell when the total amount of scum becomes large, and in the end, it is difficult to cast for a long time. was there.
　Further, in the method disclosed in Patent Document 7, since the component of the scum weir dissolves into the molten metal to exert its function, there is a problem that the component of the molten metal changes with the dissolution of the scum weir component. there were.
　Further, the method disclosed in Patent Document 8 has a problem that the amount of scum adsorbed is limited and that it cannot be used for a long time due to erosion depending on the composition of scum.
[0010]
　As described above, in the conventional technique, the entrainment of scum could not be sufficiently suppressed for a long period of time.
[0011]
　The present invention has been made in view of the above-mentioned situation, has thermal shock resistance that does not cause cracks even when in contact with molten metal in a state close to non-preheating, and melts even in a casting time of more than 6 hours. A scum adsorption member that can suppress the capture of scum into the solidification shell by absorbing and adsorbing scum into its own pores without damaging it, a double-roll type continuous casting device using this scum adsorption member, and , It is an object of the present invention to provide a method for producing a slab.
Means to solve problems
[0012]
　The gist of the present invention is as follows.
[0013]
(1) In the first aspect of the present invention, molten metal is supplied to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side dams, and a solidified shell is formed on the peripheral surface of the cooling rolls. In a twin-roll type continuous casting apparatus that grows and manufactures slabs, it is a scum adsorption member arranged so as to partially immerse in the molten metal pool portion, and is refractory containing a refractory metal oxide. It is a scum adsorption member composed of an object and having a porosity of 15% by volume or more and 70% by volume or less.
[0014]
(2) The scum suction member according to (1) above may be attached to a reinforcing member.
(3) The scum adsorption member according to (2) above may be made of a porous sheet made of ceramic fibers.
(4) In the scum adsorption member according to any one of (1) to (3) above, the refractory metal oxide is Al 2 O 3 , ZrO 2 , MgO, SiO 2 , CaO · 6Al 2 O. It may be at least one kind or two or more kinds selected from three .
(5) In the scum adsorption member according to any one of (1) to (4) above, the average diameter of the pores may be 10 μm or more and less than 50 μm.
(6) In the scum adsorption member according to any one of (1) to (5) above, the volume fraction of the pores may be 20% by volume or more and less than 50% by volume.
[0015]
(7) In the second aspect of the present invention, molten metal is supplied to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side dams, and a solidified shell is formed on the peripheral surface of the cooling rolls. A double-roll type continuous casting apparatus for growing and producing slabs, in which a part of the scum suction member according to any one of (1) to (6) above is immersed in the molten metal pool portion. It is a double-roll type continuous casting device arranged in such a manner.
[0016]
(8) In a third aspect of the present invention, molten metal is supplied to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side dams, and a solidified shell is formed on the peripheral surface of the cooling rolls. A method for producing a slab by growing it to produce a slab, wherein a part of the scum suction member according to any one of (1) to (6) above is immersed in the molten metal pool portion. It is a manufacturing method of a slab arranged in.
Effect of the invention
[0017]
　According to the present invention, it has thermal shock resistance that does not cause cracks even when it comes into contact with molten metal in a state close to non-preheating, and scum is formed in its own pores without melting even in a casting time of more than 6 hours. It is possible to provide a scum adsorption member capable of suppressing trapping of scum in a solidified shell by absorbing / adsorbing and removing, a twin-roll type continuous casting apparatus using this scum adsorption member, and a method for producing a slab. ..
[0018]
　More specifically, according to the scum adsorption member described in (1) to (6) above, it is composed of a refractory material containing a refractory metal oxide, and the volume fraction of pores is 15% by volume or more. Therefore, the absorption allowance for thermal expansion is secured, the thermal shock resistance is improved, and the scum can be sufficiently adsorbed by the pores. On the other hand, since the volume ratio of the pores is 70% by volume or less, the strength is ensured, and breakage due to the flow of molten metal or the like can be suppressed. As described above, it is possible to sufficiently suppress the entrainment of scum for a long period of time while being excellent in thermal shock resistance, and it is possible to stably cast slabs.
[0019]
　In particular, according to the scum suction member described in (2) above, since the strength of the scum suction member is secured by the reinforcing member, breakage due to the flow of molten metal or the like can be suppressed. Further, the size of the scum suction member can be reduced, and maintenance such as replacement and repair becomes easy.
[0020]
　Further, according to the scum suction member described in (3) above, the scum suction member attached to the reinforcing member is composed of a porous sheet made of ceramic fibers, so that the structure is very simple. In addition, by selecting an appropriate porous sheet in consideration of thermal conductivity, heat resistance, etc. according to the casting conditions, it is possible to accurately suppress the formation and growth of bare metal on the surface of the scum adsorption member. It becomes.
[0021]
　Further, according to the scum adsorption member described in (4) above, by selecting a material having various characteristics such as scum adsorption, heat impact resistance, and corrosion resistance to scum, scum adsorption according to various casting conditions is performed. The members can be applied, and stable casting can be performed for a long time.
[0022]
　Further, according to the scum adsorption member described in (5) above, since the average diameter of the pores is within the range of 10 μm or more and less than 50 μm, the scum can be sufficiently adsorbed. The average diameter of the pores is measured by the mercury intrusion method (JIS R 1655 (2003)), and the pore diameter having a cumulative volume fraction of 50% is defined as the “average diameter of the pores”.
[0023]
　Further, according to the scum adsorption member described in (6) above, since the volume fraction of the pores is 20% by volume or more, the absorption allowance for thermal expansion is accurately secured, and the thermal shock resistance is sufficiently improved. At the same time, the scum can be sufficiently adsorbed by the pores. On the other hand, since the volume ratio of the pores is 50% by volume or less, the strength is sufficiently secured, and breakage due to the flow of molten metal or the like can be suppressed.
[0024]
　Further, according to the twin-roll type continuous casting apparatus and the method for manufacturing slabs according to the above (7) and (8), since the above-mentioned scum suction member is arranged in the molten metal pool portion, the scum suction member The scum can be adsorbed and the scum can be prevented from being caught in the cooling roll. In addition, it has excellent thermal shock resistance and strength, and can be used for a long time. Therefore, a slab having excellent surface quality can be stably cast.
A brief description of the drawing
[0025]
FIG. 1 is an explanatory view showing an example of a twin-roll type continuous casting apparatus using a scum suction member according to an embodiment of the present invention.
FIG. 2 is a partially enlarged explanatory view of the twin-roll type continuous casting apparatus shown in FIG.
FIG. 3 is a cross-sectional explanatory view of a molten steel pool portion of the twin-roll type continuous casting apparatus shown in FIG.
FIG. 4 is a schematic top view of the molten steel pool portion shown in FIG. 3, showing the flow of molten steel discharged from the immersion nozzle.
FIG. 5 is an explanatory view showing a mode in which the scum suction member is attached to the reinforcing member.
Mode for carrying out the invention
[0026]
　As a result of diligent studies by the present inventors in order to solve the above problems, the following findings were obtained.
　Conventionally, as a measure for stable use of the scum weir, the main focus has been on a method of suppressing scum adhesion to the scum weir. Specifically, a method has been adopted in which contact with the scum is prevented by using a material system containing C which is difficult to get wet with the scum. However, this method has a problem that scum is trapped in the solidified shell and the slab quality is deteriorated. Further, in the material system containing C, there is a problem that the adhesion of the bare metal to the scum weir progresses, which is detached and is caught in the thin-walled slab. These are due to the property of C that it has high thermal conductivity and is hard to get wet with slag, and it is difficult to solve these problems when C is used.
[0027]
　Meanwhile, in order to suppress the capture of the scum of the slab, Al 2 O 3 Method of adsorbing scum scum dams quality was considered. However, the amount of scum adsorbed is low simply by using Al 2 O 3 quality, and when it is used for scum having a composition containing CaO, the scum weir is melted and damaged, resulting in durability. There was a difficulty. As described above, none of the conventionally studied methods sufficiently satisfy the characteristics required for the scum weir.
[0028]
　After diligent research, the present inventors have made it possible to realize high heat-resistant impact resistance by appropriately controlling the pores of the scum dam, and the pores become the scum adsorption allowance and scum. It was found that when the porosity (hereinafter, also referred to as porosity) is high, the adhesion of the metal can be suppressed due to the high heat insulating property while maintaining the adsorption of the stomata for a long time. Furthermore, it was found that by appropriately controlling the materials that make up the scum weir, the erosion rate due to scum can be reduced even for a scum weir with a high porosity, and high corrosion resistance can also be achieved. It was.
[0029]
　Hereinafter, the scum adsorption member according to the embodiment of the present invention made based on the above findings will be described with reference to the attached drawings. In the following embodiments, the metal to be cast will be described as steel. The present invention is not limited to the following embodiments.
　In the present embodiment, molten steel is used as the molten metal, and a slab 1 made of a steel material is manufactured. The steel types include, for example, 0.001 to 0.01% C ultra-low coal steel, 0.02 to 0.05% C low coal steel, 0.06 to 0.4% C medium coal steel, 0.5. ~ 1.2% C high coal steel, austenite stainless steel represented by SUS304 steel, ferrite stainless steel represented by SUS430 steel, 3.0 ~ 3.5% Si directional electromagnetic steel, 0.1 ~ Examples thereof include 6.5% Si non-directional electromagnetic steel (% is mass%).
　Further, in the present embodiment, the width of the manufactured slab 1 is within the range of 200 mm or more and 1800 mm or less, and the thickness is within the range of 0.8 mm or more and 5 mm or less.
[0030]
　The twin roll type continuous casting apparatus 10 to which the scum suction member 20 according to the present embodiment is applied will be described.
　The twin-roll type continuous casting apparatus 10 is an apparatus for manufacturing a slab 1, and as shown in FIGS. 1 to 4, a pair of cooling rolls 11 and 11, upstream pinch rolls 12 and 12 and downstream pinch It includes rolls 13 and 13, a pair of side weirs 15 and 15, a tundish 18, and a dipping nozzle 19.
　The upstream pinch rolls 12 and 12 and the downstream pinch rolls 13 and 13 are provided on the downstream side of the pair of cooling rolls 11 and 11 to support the slab 1.
　The pair of side weirs 15 and 15 are arranged at both ends in the width direction of the pair of cooling rolls 11 and 11. Then, the molten steel pool portion 16 is defined by the pair of cooling rolls 11 and 11 and the pair of side weirs 15 and 15.
　The tundish 18 holds the molten steel 3 and supplies the molten steel 3 to the molten steel pool portion 16 via a dipping nozzle 19 extending downward from the bottom surface thereof.
[0031]
　In the twin roll type continuous casting apparatus 10, the molten steel 3 is brought into contact with the rotating cooling rolls 11 and 11 to be cooled, so that the solidified shells 5 and 5 grow on the peripheral surfaces of the cooling rolls 11 and 11. .. Then, the solidified shells 5 and 5 formed on the pair of cooling rolls 11 and 11 are pressure-bonded to each other at the roll kiss point, whereby the slab 1 having a predetermined thickness is cast.
[0032]
　Here, as shown in FIG. 3, the molten steel 3 is stored in the molten steel pool portion 16, and a scum X made of an alumina film or the like is formed on the molten steel surface.
　A scum suction member 20 is arranged in the molten steel pool portion 16 in order to prevent the scum X from being caught in the cooling roll 11. More specifically, as shown in FIGS. 2 to 4, the scum suction member 20 is arranged between the immersion nozzle 19 and the cooling rolls 11 and 11, and a part thereof is immersed in the molten steel 3.
[0033]
　Here, the scum suction member 20 according to the present embodiment has a rectangular flat plate shape, and as shown in FIG. 3, the immersion depth (vertical depth) D in the molten steel 3 is 5 mm or more. There is. When the immersion depth D is less than 5 mm, the scum X may slip through the scum suction member 20 due to the waviness and surface flow of the surface of the molten steel pool portion 16.
　FIG. 4 is a schematic top view showing the flow of the molten steel 3 discharged from the immersion nozzle 19. As shown in FIG. 4, when the immersion depth D is 5 mm or more, the molten steel 3 can be circulated stably, so that the scum can be reliably adsorbed on the scum suction member 20. ..
[0034]
　The scum adsorption member 20 according to the present embodiment is made of a refractory (atypical refractory or a fixed brick) containing a refractory metal oxide, and has a pore volume ratio of 15% by volume or more and 70% by volume. It is as follows. Preferably, the volume fraction of the pores is 20% by volume or more and less than 50% by volume.
　Further, in the scum adsorption member 20 of the present embodiment, it is preferable that the average diameter of the pores is 10 μm or more and less than 50 μm.
　Further, as the above-mentioned refractory metal oxide, it is preferable to use at least one or more selected from Al 2 O 3 , ZrO 2 , MgO, SiO 2 , and CaO · 6 Al 2 O 3 .
[0035]
　The reasons why the volume fraction of the pores of the scum adsorption member 20, the average diameter of the pores, and the refractory metal oxide are defined as described above will be described below.
[0036]
(Volume Ratio of Pore)
　The scum adsorption member 20 of the present embodiment has pores as described above, and the pores improve heat impact resistance by securing an absorption allowance for thermal expansion and an adsorption allowance for scum. It is possible to obtain the effects such as the addition of the metal and the suppression of the adhesion of the bare metal by reducing the heat transfer path.
　Here, if the volume ratio of the pores is less than 15% by volume, the above-mentioned effects of the pores may not be exhibited. On the other hand, if the volume fraction of the pores exceeds 70% by volume, the strength is insufficient and there is a risk of breakage due to the molten steel flow.
　Therefore, in the scum adsorption member 20 of the present embodiment, the volume fraction of the pores is set within the range of 15% by volume or more and 70% by volume or less.
　It is preferable that the lower limit of the volume fraction of the pores is 20% by volume or more in order to ensure that the above-mentioned effects of the pores are effective. Further, in order to surely suppress breakage due to the molten steel flow, it is preferable that the upper limit of the volume fraction of the pores is less than 50% by volume.
[0037]
　Here, the porosity of the scum adsorption member 20 can be controlled by using a lightweight aggregate, organic fibers, or adjusting the amount of water used during kneading.
　Since the lightweight aggregate itself has pores, it is possible to improve the porosity after molding. Further, since the organic fibers and water disappear during heating and generate bubbles inside the molded product, the porosity can be improved.
[0038]
(Average diameter
　of pores ) The pores in the scum adsorption member 20 have an action of adsorbing scum as described above. Here, by setting the average diameter of the pores to 10 μm or more, the amount of scum permeation is secured and the scum can be sufficiently adsorbed. On the other hand, by setting the average diameter of the pores of the scum suction member 20 to less than 50 μm, the pores of the scum suction member 20 and the scum come into sufficient contact with each other, and the scum can be sufficiently sucked.
　Therefore, in the scum suction member 20 of the present embodiment, the average diameter of the pores is set within the range of 10 μm or more and less than 50 μm. In order to ensure that the scum adsorption action is effective, the lower limit of the average diameter of the pores in the scum adsorption member 20 is preferably 25 μm or more, and the upper limit of the average diameter of the pores is more preferably 40 μm or less. ..
[0039]
　The average diameter of the pores in this embodiment was measured by the mercury intrusion method (JIS R 1655 (2003)), and the pore diameter having a cumulative volume fraction of 50% was defined as the “average diameter of the pores”.
　Further, the average diameter of the pores can be adjusted by appropriately controlling the amount of organic fibers added and the amount of water during kneading. As a result, in the scum adsorption member 20 of the present embodiment, the amount and diameter of pores that contribute to the adsorption of scum can be controlled, unlike a material having simply many pores such as a so-called porous heat insulating material. ..
[0040]
(Refractory metal oxide)
　The refractory metal oxide constituting the scum suction member 20 is this embodiment, Al 2 O 3 , ZrO 2 , MgO, SiO 2 , CaO · 6Al 2 O 3 is selected from At least one kind or two or more kinds can be used.
[0041]
　When Al 2 O 3 is selected as the main component, the scum adsorption member 20 having a relatively high strength even with a high porosity can be obtained. When Al 2 O 3 was selected as the main component, by blending other components described later , the deterioration of corrosion resistance due to Al 2 O 3 having high adsorptivity was suppressed by other components to make it porous. Even in this case, it is possible to obtain a scum adsorption member 20 having high durability by suppressing erosion due to scum while maintaining strength.
[0042]
　When ZrO 2 is selected as the main component, the ability to suppress the adhesion of bare metal can be improved due to its low thermal conductivity, and the effect of improving the corrosion resistance to scum can be obtained from the high corrosion resistance to CaO.
　When CaO ・ 6Al 2 O 3 is selected as the main component, high porosity can be easily realized due to its plate-like structure, scum adsorption capacity can be improved, and corrosion resistance to scum can be obtained due to its high corrosion resistance to FeO. An improvement effect can be obtained.
[0043]
　When MgO is selected as the main component, higher corrosion resistance to scum can be obtained as compared with the above-mentioned CaO · 6Al 2 O 3 and ZrO 2 due to the high corrosion resistance to CaO and FeO .
　When SiO 2 is selected as the main component, the effect of improving thermal shock resistance can be obtained due to its low coefficient of thermal expansion. As a result, when it is desired to have a relatively low porosity with an emphasis on corrosion resistance, it is possible to obtain durability that can be used stably even with a material that may have a reduced thermal shock resistance.
[0044]
　The scum adsorption member 20 according to the present embodiment as described above is made of a refractory material containing a refractory metal oxide, and the volume fraction of the pores in the scum adsorption member 20 is 15% by volume or more. The absorption allowance for expansion is secured, the thermal shock resistance is improved, and the scum can be sufficiently adsorbed by the pores. On the other hand, since the volume fraction of the pores is 70% by volume or less, the strength is ensured, and breakage due to the flow of the molten steel 3 or the like can be suppressed.
　Therefore, it is possible to sufficiently suppress the entrainment of scum for a long period of time while having excellent thermal shock resistance, and it is possible to stably cast the slab 1.
[0045]
　Further, in the scum suction member 20 according to the present embodiment, since the average diameter of the pores is within the range of 10 μm or more and less than 50 μm, the scum sufficiently penetrates into the pores of the scum suction member 20, and the scum can be accurately permeated. Can be adsorbed on. Therefore, it is possible to further suppress the entrainment of the scum in the slab 1, and it is possible to manufacture the slab 1 having excellent surface quality.
[0046]
　Further, in the scum adsorption member 20 according to the present embodiment, the refractory metal oxide is at least one or two selected from Al 2 O 3 , ZrO 2 , MgO, SiO 2 , and CaO · 6 Al 2 O 3. As described above, by selecting a material having excellent various characteristics such as scum adsorption, thermal shock resistance, and corrosion resistance to scum, the scum adsorption member 20 can be applied according to various casting conditions for a long time. It becomes possible to stably cast the slab 1.
[0047]
　Further, according to the method for manufacturing the twin roll type continuous casting apparatus 10 and the slab 1 using the scum suction member 20 according to the present embodiment, a part of the scum suction member 20 is arranged so as to be immersed in the molten steel pool portion 16. Since it is provided, the scum can be sufficiently adsorbed by the scum suction member 20. Therefore, it is possible to prevent the scum from being caught in the cooling roll 11. Further, since the scum suction member 20 is excellent in heat impact resistance and corrosion resistance, it can be used stably for a long time. Therefore, it is possible to stably cast the slab 1 having excellent surface quality.
[0048]
　The scum suction member according to the embodiment of the present invention, and the twin-roll type continuous casting apparatus and the method for manufacturing a slab using the scum suction member have been specifically described above, but the present invention is not limited thereto. , It can be changed as appropriate without departing from the technical idea of ​​the invention.
　For example, in the present embodiment, as shown in FIG. 1, a twin-roll type continuous casting apparatus in which pinch rolls are arranged has been described as an example, but the arrangement of these rolls and the like is not limited, and the design is appropriately changed. You may.
　Further, in the present embodiment, as shown in FIG. 1, the upper end of the scum suction member 20 is connected to the bottom of the tundish 18, but the scum suction member 20 is suspended from the bottom of the tundish 18 by a rod-shaped member. You may.
[0049]
　In the above embodiment, the case where the scum suction member 20 is used as a single unit has been described, but the present invention is not limited to this. For example, as shown in FIG. 5, the scum suction member 20 may be attached to the reinforcing member 21 and used as a complex.
[0050]
　Since phenomena such as adsorption of scum and adhesion of bare metal occur at the contact interface with the molten metal, if the scum adsorption member 20 is arranged at least at a portion in contact with the molten metal, the same action and effect as those in the above embodiment can be obtained. It becomes possible to play. Therefore, by forming a composite of the scum suction member 20 and the reinforcing member 21, the size of the scum suction member 20 can be reduced, and maintenance such as replacement and repair becomes easy.
[0051]
　As described above, since the reinforcing member 21 that does not come into contact with the molten metal can obtain the effect without particularly limiting the porosity, the properties other than the scum adsorption property can be maintained at the same level as the conventional material. It is preferable that only the scum adsorption member 20 at which adsorption occurs is porous, and the porosity of the reinforcing member 21 is about the same as that of the conventional material. Similarly, the material of the reinforcing member 21 is not limited to the same material as the scum suction member 20.
[0052]
　For the composite of the scum suction member 20 and the reinforcing member 21, for example, an amorphous refractory material is used, and the reinforcing member 21 for ensuring the strength with a high density is first cast, and then the scum suction member 20 is made porous around the reinforcing member 21. It can be produced by casting separately using a gold frame or a foam frame so that a quality material can be constructed. It can also be produced by separately casting the reinforcing member 21 and the scum suction member 20 and adhering them with mortar.
[0053]
　Further, in the case of forming a composite of the scum suction member 20 and the reinforcing member 21, a porous sheet made of ceramic fibers may be used as the scum suction member 20. The ceramic fiber may be, for example, an alumina fiber or a zirconia fiber. When such a porous sheet is used, it is possible to easily form a complex by attaching it to one side or both sides of the reinforcing member 21 or wrapping it around the reinforcing member 21.
[0054]
　Here, in the complex shown in FIG. 5, when the thickness of the scum adsorption member 20 exceeds 0.5 mm, a scum adsorptionable portion is secured, and the scum adsorption effect can be maintained for a long time. Become. Therefore, in the complex shown in FIG. 5, the thickness of the scum suction member 20 is preferably more than 0.5 mm, more preferably more than 3 mm.
　The scum adsorption is caused by the open pores on the surface of the scum adsorption member 20, but most of the open pores are within 10 mm from the surface, so even if the thickness of the scum adsorption member 20 exceeds 10 mm. The contribution to the effect of scum adsorption is small. Therefore, in the complex shown in FIG. 5, the upper limit of the thickness of the scum suction member 20 is preferably 10 mm or less.
Example
[0055]
　The results of experiments carried out in order to confirm the effects of the present invention will be described below.
[0056]
　Using the refractory metal oxides shown in Tables 1 and 2, cotton was added as a baking material to the formulation in which 11 mass% of alumina cement was added externally, kneaded with water, and poured into a mold for 24 hours. After curing, the scum adsorption member was prepared by drying at 110 ° C. for 24 hours. Porosity was controlled by the amount of burnt material and added water. In addition, the burnt material and the added moisture in Tables 1 and 2 both mean the mass% of the outer cover.
[0057]
　With respect to the obtained scum adsorption member, the volume fraction of pores, the average diameter of pores, thermal shock resistance, scum adsorption resistance, corrosion resistance, and adhesion of bare metal were evaluated as follows. The evaluation results are shown in Tables 3 and 4.
[0058]
(Volume ratio of
　pores ) The volume fraction of pores (apparent porosity) was measured by the boiling method (JIS R 2205 (1992)). The volume fraction of the pores in the surface layer region of the multi-layered scum adsorption member was measured after cutting and removing only the surface layer region.
[0059]
(Average diameter of
　pores ) The average diameter of pores was measured by the mercury intrusion method (JIS R 1655 (2003)). The average diameter of the pores in the surface layer region of the multi-layered scum adsorption member was measured after cutting and removing only the surface layer region.
[0060]
(Heat-resistant impact resistance) In
　the evaluation of heat-resistant impact resistance, a heat-resistant impact resistance test was conducted under the condition that a refractory of 40 mm × 40 mm × 160 mm was immersed in hot metal at 1550 ° C., held for 5 minutes, and then air-cooled. By repeating this series of heating and cooling operations, those that broke within 5 times were "Bad", those that broke during the cycle of 5 to 10 times were "Good", and those that broke within 11 times could be maintained without breakage. The thing was written as "Very Good".
[0061]
(Adsorption of
　scum ) The adsorptivity of scum is the weight after floating 200 g of scum in hot metal at 1550 ° C, immersing a refractory processed into a shape of 40 mm × 100 mm × 25 mm in the hot metal, and holding it for 30 minutes. Evaluated by increment. Tables 3 and 4 show values ​​standardized by increasing the weight of the scum suction member shown in Example 1. The composition of scum 38% FeO-24% Al in a weight ratio 2 O 3 -14% CaO-24% SiO 2 was. When the numerical value is large, it means that a large amount of scum is adsorbed to the scum adsorption member, which means that the scum adsorption ability can be maintained for a long time. Since the use of molten steel causes the adhesion of bare metal, a test was conducted using hot metal in order to evaluate the adsorptivity of scum only. The acceptance criteria were 100 or more.
[0062]
(Corrosion resistance) For
　corrosion resistance to scum, 200 g of scum is floated on molten steel at 1550 ° C., a refractory of φ50 mm × 150 mm is immersed in this molten steel to give rotation of 150 rpm, and the dimensional change of the interface between scum and molten steel is measured. It was evaluated in. Tables 3 and 4 show values ​​standardized by dimensional changes in the scum suction member shown in Example 1. A large value indicates that erosion is likely to proceed with respect to the scum, indicating that the risk of breakage due to erosion during use increases. The acceptance criteria were those over 80.
[0063]
(Adhesion of
　bare metal ) Adhesion of bullion is determined by increasing the weight before and after immersing a refractory of 40 mm x 40 mm x 160 mm in molten steel at 1580 ° C., holding it for 10 seconds, and then pulling it up from the molten steel and air-cooling it. evaluated. Tables 3 and 4 show values ​​standardized by increasing the weight of the scum suction member shown in Example 1. A large number indicates that more bullion is attached and that the risk of bullion entrainment in the slab is high. The acceptance criteria were 100 or less.
[0064]
[table 1]

[0065]
[Table 2]

[0066]
[Table 3]

[0067]
[Table 4]

[0068]
　As the volume fraction of pores (apparent porosity) increased, the amount of scum adsorbed increased and the amount of bare metal adhered tended to decrease. On the other hand, although the corrosion resistance decreases when the volume fraction of pores (apparent porosity) is increased, the result is that the decrease in corrosion resistance can be suppressed by using ZrO 2 , MgO, and CA6 (CaO · 6Al 2 O 3 ). It was. In addition, the use of SiO 2 resulted in the improvement of the thermal shock resistance of the scum suction member.
[0069]
　From the above results, according to the present invention, it has thermal shock resistance that does not cause cracks even when it comes into contact with molten metal in a state close to non-preheating, and it does not melt even in a casting time of more than 6 hours. It was confirmed that it is possible to provide a scum adsorption member capable of suppressing trapping of scum in a solidified shell by absorbing and adsorbing and removing scum in the pores having the scum.
Industrial applicability
[0070]
　According to the present invention, it has thermal shock resistance that does not cause cracks even when it comes into contact with molten metal in a state close to non-preheating, and scum is formed in its own pores without melting even in a casting time of more than 6 hours. It is possible to provide a scum suction member capable of suppressing trapping of scum in a solidification shell by absorbing / adsorbing and removing, a twin-roll type continuous casting apparatus using this scum suction member, and a method for manufacturing a slab. it can.
Code description
[0071]
1 Thin-walled slab (slab)
3 Molten steel
5 Solidified shell
11 Cooling roll
16 Molten steel pool part (molten metal pool part)
20 Scum suction member
21 Reinforcing member
The scope of the claims
[Claim 1]
　A twin roll type in which molten metal is supplied to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side dams, and a solidified shell is formed and grown on the peripheral surface of the cooling rolls to produce slabs. In a continuous casting apparatus, it is a scum adsorption member arranged so as to partially immerse in the molten metal pool portion, and is
　composed of a refractory material containing a refractory metal oxide, and has a porosity of pores.
A scum suction member having a content of 15% by volume or more and 70% by volume or less .
[Claim 2]
　The scum suction member according
to claim 1, wherein the scum suction member is attached to a reinforcing member.
[Claim 3]
　The scum adsorption member according to
claim 2, wherein the scum adsorption member is composed of a porous sheet made of ceramic fibers .
[Claim 4]
Claim 1 according to claim 1, 　wherein the refractory metal oxide is at least one kind or two or more kinds selected from Al 2 O 3 , ZrO 2 , MgO, SiO 2 , and CaO · 6 Al 2 O 3. Item 3. The scum suction member according to any one of items 3.
[Claim 5]
　The scum adsorption member according to any one of claims 1 to 4, wherein the average diameter of the pores is 10 μm or more and less than 50 μm.
[Claim 6]
　The scum adsorption member according to any one of claims 1 to 5, wherein the volume fraction of the pores is 20% by volume or more and less than 50% by volume.
[Claim 7]
　A twin-roll continuous type in which molten metal is supplied to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side dams, and a solidified shell is formed and grown on the peripheral surface of the cooling rolls to produce slabs. a casting apparatus,
　part of the scum suction member as claimed in any one of claims 6 is disposed so as to dip into the molten metal pool portion
, wherein the bi Roll type continuous casting equipment.
[Claim 8]
　Manufacture of slabs in which molten metal is supplied to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side dams, and a solidified shell is formed and grown on the peripheral surface of the cooling rolls to produce slabs. A method for producing a slab, which comprises arranging a
　part of the scum suction member according to any one of claims 1 to 6 so as to
be immersed in the molten metal pool portion. Method.