CN113365759B - Control method of sliding gate valve device and manufacturing method of cast piece - Google Patents
Control method of sliding gate valve device and manufacturing method of cast piece Download PDFInfo
- Publication number
- CN113365759B CN113365759B CN202080011512.1A CN202080011512A CN113365759B CN 113365759 B CN113365759 B CN 113365759B CN 202080011512 A CN202080011512 A CN 202080011512A CN 113365759 B CN113365759 B CN 113365759B
- Authority
- CN
- China
- Prior art keywords
- molten steel
- nozzle
- ladle
- gate valve
- pouring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/18—Controlling or regulating processes or operations for pouring
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/14—Closures
- B22D41/22—Closures sliding-gate type, i.e. having a fixed plate and a movable plate in sliding contact with each other for selective registry of their openings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/14—Closures
- B22D41/22—Closures sliding-gate type, i.e. having a fixed plate and a movable plate in sliding contact with each other for selective registry of their openings
- B22D41/42—Features relating to gas injection
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
Abstract
Provided are a method for controlling a sliding gate valve device and a method for manufacturing a cast piece, wherein occurrence of non-tapping can be suppressed during re-pouring of molten steel at a ladle. Comprising the following steps: a gas blowing step of, in a state in which the ladle (1) contains the molten steel (4), placing the slide plate (32) at an open position, pouring out a part of the molten steel (4) from the ladle (1) through the 1 st nozzle (311) and the 2 nd nozzle (321), and then moving the slide plate (32) to a closed position, and blowing inert gas into the molten steel (4) in the ladle (1) from the gas blowing hole (322) through the 1 st nozzle (311); and a re-pouring step of pouring molten steel (4) from the ladle (1) through the 1 st nozzle (311) and the 2 nd nozzle (321) by placing the slide plate (32) at an open position after the gas blowing step, wherein the blowing amount of the inert gas is set to 3.9Nm in the gas blowing step 3 /(min·m 2 ) Above and 26.0Nm 3 /(min·m 2 ) The following is given.
Description
Technical Field
The present invention relates to a method for controlling a sliding gate valve device and a method for manufacturing a cast piece.
Background
In a ladle (tundish) or a ladle holding vessel used in a steelmaking process in a steel plant, a sliding gate valve device is provided at the bottom of the vessel. A slide gate nozzle device provided at the bottom of a ladle is generally filled with a drainage sand for preventing molten steel from entering a nozzle hole and solidifying to a non-perforated state until molten steel is poured out, such as during pouring. This drainage sand may cause a decrease in cleanliness in the casting of high-cleanliness steel, and thus an operation method of casting after once discharging the drainage sand may be performed. In such an operation method, the sliding gate valve device is opened and the ladle is poured with the ladle placed at the drainage sand discharge position and with the drainage sand and a part of molten steel from the ladle. Then, the sliding gate valve device is closed, and pouring of molten steel is stopped. Further, a ladle is placed at a casting position where casting is performed, and a sliding gate valve device is opened to pour molten steel from the ladle and transfer the molten steel to a tundish or a mold. Then, the poured molten steel solidifies, thereby producing a cast piece having a predetermined cross-sectional shape.
In such a method for producing a cast piece, when the sliding gate valve device is closed after molten steel is poured out once, molten steel remains in the nozzle hole without being filled with the drainage sand. When the sliding nozzle device is opened again, at least a part of the molten steel remaining in the nozzle hole of the sliding nozzle device occasionally solidifies, and therefore, even if the sliding nozzle device is opened, the molten steel may not be poured out (unnatural opening). The phenomenon of such unnatural opening is also referred to as "no opening". When no hole is formed, oxygen purging (oxygen purging) is required in which forced hole formation is performed by blowing oxygen. However, when oxygen purging is performed, there is a problem that inclusions are generated due to oxidation reaction of metals in molten steel. In addition, there are cases where no holes are formed even when oxygen purging is performed, and casting is stopped.
As a technique for preventing a non-opening hole at a sliding gate valve device, for example, patent document 1 discloses the following technique: in the initial opening of the tundish at the slide gate device, the plate is intermittently operated, and gas is blown from the plate into the nozzle hole (hereinafter also referred to as "gas bubbling").
Prior art literature
Patent literature
Patent document 1 Japanese patent laid-open No. 7-80611
Disclosure of Invention
Problems to be solved by the invention
However, the technique described in patent document 1 is a technique of initial tapping at a sliding gate valve device of a tundish, and is not a technique at the time of re-pouring of the sliding gate valve device of a ladle. In patent document 1, it is preferable that the time for bubbling the gas is short, and even if the bubbling of the gas is performed in the ladle for this time, the bubbling of the gas is inevitably performed at a constant frequency.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a control method of a sliding gate valve device and a method of manufacturing a cast piece capable of suppressing occurrence of non-tapping at the time of re-pouring of molten steel in a ladle.
Means for solving the problems
According to one aspect of the present invention, there is provided a method for controlling a sliding gate valve device for pouring molten steel from a ladle containing molten steel through a sliding gate valve device provided in the ladle, the sliding gate valve device comprising: an upper plate which is arranged on the lower surface of an upper nozzle fixed at the bottom of the ladle and is provided with a 1 st spray hole; and a slide plate provided on a lower surface of the upper plate and having a 2 nd nozzle hole, the slide plate being configured to be movable by sliding a lower surface of the upper plate from an open position, in which at least a part of the 2 nd nozzle hole overlaps the 1 st nozzle hole, to a closed position, in which the 2 nd nozzle hole does not overlap the 1 st nozzle hole and the 1 st nozzle hole is blocked by the slide plate, the slide plate further having a gas blowing hole into which an inert gas is blown into the 1 st nozzle hole at the closed position, the control method of the slide gate device comprising: pouring step of placing the slide plate at the open position in a state where the ladle contains the molten steel, from above through the 1 st nozzle and the 2 nd nozzlePouring a part of the molten steel from the ladle; a gas blowing step of moving the slide plate to the closed position after the pouring step, and blowing the inert gas from the gas blowing hole to the molten steel in the ladle through the 1 st nozzle hole; and a re-pouring step of pouring the molten steel from the ladle through the 1 st nozzle and the 2 nd nozzle by placing the slide plate at the open position after the gas blowing step, wherein a blowing flow rate of the inert gas is set to 3.9Nm in the gas blowing step 3 /(min·m 2 ) Above and 26.0Nm 3 /(min·m 2 ) The flow rate of the inert gas is set to be the volume of the inert gas blown per unit time per the cross-sectional area of the nozzle hole of the upper nozzle.
According to one aspect of the present invention, there is provided a method for producing a cast piece by pouring molten steel from a ladle containing molten steel through a sliding gate valve provided in the ladle and casting the poured molten steel, wherein the molten steel poured in the re-pouring step is cast by the control method of the sliding gate valve described above.
ADVANTAGEOUS EFFECTS OF INVENTION
According to one aspect of the present invention, a control method of a sliding gate valve apparatus and a method of manufacturing a cast piece, which are achieved in view of the above-described problems, can be provided that can suppress occurrence of non-tapping during re-pouring of molten steel at a ladle.
Drawings
Fig. 1 is a sectional view showing a sliding gate valve device in a closed state.
Fig. 2 is a cross-sectional view showing the sliding gate valve device in an open state.
Fig. 3 is a schematic view showing a case where the blowing time is short in the blowing process.
Fig. 4 is a schematic view showing a case where the blowing time is long in the blowing process.
Fig. 5 is a cross-sectional view showing a sliding gate valve device according to a modification of the present invention in a closed state.
Fig. 6 is a cross-sectional view showing a sliding gate valve device according to a modification of the present invention in an open state.
Fig. 7 is a graph showing the calculation result of the homogeneous mixing time of the embodiment.
Fig. 8 is a graph showing the results of the hole forming success rates of the examples and the comparative examples.
Detailed Description
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, at least 1 or more embodiments can of course be implemented even without the description of the specific details. In addition, the drawings show well-known structures and devices in simplified schematic representations for brevity.
A method of controlling a sliding gate valve device 3 and a method of manufacturing a cast piece according to an embodiment of the present invention will be described with reference to fig. 1 to 4. The cast piece manufacturing method according to the present embodiment is a manufacturing method for a continuous casting apparatus for continuously casting molten steel 4 stored in a ladle 1 shown in fig. 1 and 2.
The ladle 1 is a molten steel holding vessel that accommodates molten steel 4 and slag 5. Molten steel 4 stored in the ladle 1 is refined to a predetermined composition and temperature in advance. In the present embodiment, it is preferable to use high-cleanliness steel such as bearing steel as the type of molten steel 4. The ladle 1 is provided with an upper nozzle 2 and a sliding gate valve device 3.
The upper nozzle 2 is a nozzle made of refractory material fixed to the bottom of the ladle 1.
The sliding gate valve device 3 is a nozzle mechanism provided on the lower surface of the upper nozzle 2, and includes an upper plate 31, a sliding plate 32, and a lower nozzle 33.
The upper plate 31 is a plate made of a refractory material, and has a circular 1 st nozzle 311 that opens in the vertical direction (vertical direction in fig. 1 to 4) in the plate surface. The upper plate 31 is fixedly provided on the bottom surface of the ladle 1, and is provided so that the circular hole of the upper nozzle 2 overlaps the 1 st nozzle hole 311 concentrically when viewed from the vertical direction. The aperture of the upper nozzle 2 is substantially the same size as the aperture of the 1 st nozzle 311, and is also substantially the same size as the apertures of the 2 nd nozzle 321 and the lower nozzle 33 described later.
The slide plate 32 is a plate made of a refractory material, and has a gas blowing hole 322 and a circular 2 nd nozzle 321 that opens in the vertical direction in the plate surface. The slide plate 32 is provided on the lower surface of the upper plate 31, and is configured to be movable in a horizontal direction (left-right direction in fig. 1 to 4) by sliding on the lower surface of the upper plate 31. The sliding operation of the slide plate 32 is performed by a sliding mechanism, not shown, such as an air cylinder.
The gas blowing hole 322 is provided at a position separated from the 2 nd nozzle hole 321 by a predetermined distance in the sliding direction of the slide plate 32. One end of the gas blowing hole 322 is opened at the upper surface of the slide plate 32, and the other end is connected to a gas supply device, not shown. In such a gas blowing hole 322, ar gas is supplied from a gas supply device, and is injected from the upper surface of the slide plate 32 on which one end of the gas blowing hole 322 is formed. The shape of the gas blowing hole 322 is not particularly limited as long as it is a hole in which the molten steel 4 is difficult to enter and Ar gas can be injected. For example, the gas blowing holes 322 may have a slit shape, a porous shape, or the like.
Further, in the present embodiment, as shown in fig. 1, a position of the slide plate 32 where the gas blowing hole 322 overlaps the 1 st nozzle 311 when viewed from the vertical direction and the 1 st nozzle 311 is closed by the slide plate 32 is set to the closed position. As shown in fig. 2, the position of the slide plate 32 where at least a part of the 2 nd nozzle 321 overlaps the 1 st nozzle 311 when viewed from the vertical direction is set as an open position. The state in which the slide plate 32 is moved to the closed position is set to the closed state of the sliding gate valve device 3, and the state in which the slide plate 32 is moved to the open position is set to the open state of the sliding gate valve device 3. That is, the slide plate 32 is configured to be movable at least from the open position to the closed position by sliding on the lower surface of the upper plate 31.
Further, the slide plate 32 can be moved in the sliding direction at the open position to adjust the overlap amount, which is the area where the 2 nd nozzle hole 321 overlaps the 1 st nozzle hole 311. By adjusting the overlap amount in this way, the pouring amount per unit time when pouring out the molten steel 4 from the sliding gate valve 3 can be adjusted. At this time, the slide plate 32 is moved from the closed position to the open position, and the range from the position where the 2 nd nozzle hole 321 and the 1 st nozzle hole 311 start to overlap to the position where they completely overlap (become concentric) is set as the open position, and the pouring amount is adjusted in this range.
The lower nozzle 33 is a nozzle made of a refractory material. The lower nozzle 33 is fixedly provided on the lower surface of the slide plate 32, and a circular hole of the lower nozzle 33 and the 2 nd nozzle hole 321 are concentrically overlapped with each other when viewed from the vertical direction.
In a stage before the start of casting and at the end of the refining process, the sliding gate valve 3 is closed, and as shown in fig. 1, the guide sand 6 enters the upper nozzle 2 and the 1 st nozzle 311 of the ladle 1. The drainage sand 6 is used to prevent the opening defect at the initial opening of the ladle 1 and to prevent solidification of the molten steel 4 in the upper nozzle 2 and the 1 st nozzle hole 311.
In the present embodiment, a pouring step of discharging the drainage sand 6 is performed before the casting is started. In the pouring step, the ladle 1 after the completion of the refining process is placed at the drainage sand discharge position, and the slide plate 32 is moved to the open position to open the slide gate valve device 3, thereby discharging all the drainage sand 6. At this time, a part of the molten steel 4 is poured out together with the drainage sand 6. In the pouring step, the ladle 1 is completely discharged with the guide sand 6, and the sliding gate valve 3 may be heated by the sensible heat of the poured molten steel. By raising the temperature of the sliding gate valve device 3, solidification of molten steel in the sliding gate valve device 3 in a re-pouring step described later can be suppressed. On the other hand, if these conditions are satisfied, the amount of molten steel 4 poured is preferably as small as possible from the viewpoint of yield. Therefore, the pouring time, which is the time for pouring a part of molten steel from the ladle 1, is preferably 5 seconds or more and 13 seconds or less. If the pouring time is set to 5 seconds or longer, the temperature of the sliding gate valve 3 increases to such an extent that molten steel in the sliding gate valve 3 does not solidify in the re-pouring step. On the other hand, if the pouring time exceeds 13 seconds, the poured molten steel becomes excessive, and for example, the yield of cast pieces to molten steel becomes less than 99%, and the reduction in the yield cannot be considered.
After the pouring step, a gas blowing step is performed to move the slide plate 32 to the closed position and set the slide gate device 3 in the closed state, and Ar gas is blown from the gas blowing hole 322 (gas bubbling is performed). In the gas blowing step, ar gas is blown from the gas blowing hole 322 into the molten steel 4 in the ladle 1 for a predetermined time or longer. The time for blowing Ar gas is also referred to as a blowing time or a bubbling time. The Ar gas blown from the gas blowing hole 322 moves upward into the ladle 1 through the 1 st nozzle hole 311 and the upper nozzle 2, and agitates the molten steel 4 stored in the ladle 1.
At this time, the blowing flow rate of the Ar gas per unit time of the blown volume was 3.9Nm in terms of the unit nozzle hole cross-sectional area of the upper nozzle 3 /(min·m 2 ) Above and 26.0Nm 3 /(min·m 2 ) The following is given. For example, when the nozzle diameter of the upper nozzle 2 is 70mm, the nozzle hole cross-sectional area of the upper nozzle 2 becomes 3.8X10 -3 m 2 Therefore, the flow rate of Ar gas per unit time blown from the upper nozzle 2 is in the range of 15NL/min to 100 NL/min. At an Ar gas blowing flow rate of less than 3.9Nm 3 /(min·m 2 ) In the case of (3), the molten steel 4 easily flows into the sliding gate valve device 3 from which the drainage sand is discharged and solidifies. On the other hand, the flow rate of Ar gas blowing exceeded 26.0Nm 3 /(min·m 2 ) In the case of (3), the flow rate of the Ar gas blown into the sliding gate valve device 3 increases, and thus the flow of the molten steel in the vicinity of the sliding gate valve device 3 caused by the Ar gas is accompanied by a vortex. In this case, a stagnation portion of the molten steel flow is formed in a region adjacent to the vortex, and the molten steel 4 in this portion is easily solidified.
In addition, as described above, the flow rate of Ar gas flowing into the upper nozzle per unit nozzle hole cross-sectional area is preferably 15NL/min to 100NL/min, more preferably 15NL/min to 50NL/min, regardless of the nozzle hole cross-sectional area of the upper nozzle. If the flow rate of Ar gas is less than 15NL/min, the stirring force is too small, and therefore the blowing time must be prolonged, and there is a possibility that the production cost will increase in order to compensate for the reduction in productivity and the molten steel temperature. On the other hand, if the flow rate of the Ar gas exceeds 50NL/min, the 1 st nozzle 311 and the upper nozzle 2 are cooled, and the temperatures of the 1 st nozzle 311 and the upper nozzle 2 are lowered, and there is a possibility that the molten steel 4 solidifies and adheres to the inside of the 1 st nozzle 311 and the upper nozzle 2. Further, when the flow rate of the Ar gas exceeds 100NL/min, the bath surface is greatly vibrated, and the operation of moving the ladle 1 from the drainage sand discharge position to the casting position where continuous casting is performed while the Ar gas is blown in becomes dangerous. In addition, there is a concern that the cleanliness of the molten steel 4 may be deteriorated due to the entrainment of slag or the like. Hereinafter, the following is also referred to as re-pouring: after the sliding gate valve device 3 is opened and the molten steel 4 is poured out, the pouring out of the molten steel 4 is stopped by temporarily closing the sliding gate valve device 3, and the pouring out of the molten steel 4 is restarted by further opening the sliding gate valve device 3.
In the gas blowing step, the blowing time is set to be the uniform mixing time t of the molten steel 4 in the ladle 1 by stirring of Ar gas m More than 1/4 of(s). Uniform mixing time t m Calculated values obtained for stirring power epsilon (W/t) by Ar gas and bath shape (bath shape) of molten steel 4 in ladle 1. In the present embodiment, as an example, a value obtained by the following expression (1) is used as the stirring power ε. In the formula (1), ε represents stirring power (W/t) or V g Represents the flow rate (Nm) of Ar gas blown in 3 /min)、T 1 The temperature (K) and W of the molten steel 4 and the weight (t) and h of the molten steel 4 are respectively shown v Represents the depth of blowing (bath depth) (m), P a Represents the atmospheric pressure (Pa), T 0 The standard state temperature (K) is indicated.
[ mathematics 1]
In the present embodiment, the uniform mixing time t is taken as an example m The calculated value obtained by the following expression (2) is used. In the formula (2), h v Indicating bath depth (m), d v The bath diameter (m) is shown. The uniform mixing time t obtained by the formula (2) m The ladle 1 shown in fig. 1 and 2 was simulated and calculated in a bottomed cylindrical shape. I.e. bath depth h v v represents the depth in the vertical direction of the molten steel 4 contained in the ladle 1, and the bath diameter d v The average value of the inner diameters of the truncated cone-shaped ladles 1 in the region where the molten steel 4 is stored is shown.
[ math figure 2]
Here, it is considered that, when the ladle 1 having the sliding gate valve 3 is used for the re-pouring, in the case where the sliding gate valve 3 is closed and the gas bubbling is performed in a state where the injection is stopped, the amount of solidification of molten steel can be suppressed for a short time, and the non-tapping can be prevented. For example, patent document 1 describes that in a sliding gate valve device of a tundish, molten steel solidifies when the gas bubbling time is prolonged.
The inventors examined the relationship between the blowing time and the non-tapping in the sliding gate valve 3 of the ladle 1, and found that the blowing time was shorter than the homogeneous mixing time t m The probability of occurrence of no opening is increased for 1/4 of the cases. This can be presumed to be the following cause of the phenomenon. In the gas bubbling in the ladle 1, as shown in fig. 3, when the blowing time is short, stirring of the molten steel 4 is not sufficiently performed, and a large temperature gradient is generated between the molten steel 4 at the upper part and the bottom part of the ladle 1. Therefore, the temperature in the upper nozzle 2 and/or the 1 st nozzle hole 311 becomes low, and the solidification development possibility of the molten steel 4 becomes high, so that the probability of occurrence of non-tapping becomes high. On the other hand, as shown in FIG. 4, when the blowing time is long, stirring of the molten steel 4 is sufficiently performed, and thus the molten steel is poured into the ladle 1The temperatures of the upper and bottom molten steels 4 are equalized. Therefore, the temperature in the upper nozzle 2 and in the 1 st nozzle hole 311 increases, and solidification of the molten steel 4 can be suppressed, so that occurrence of non-tapping can be suppressed. In order to obtain such an effect of suppressing occurrence of non-perforation, the blowing time is set to be a uniform mixing time t m The above is important. On the other hand, if the blowing time is too long, the entire temperature of the molten steel 4 is undesirably lowered. Therefore, the upper limit of the blowing time is preferably 2/5 or less of the homogeneous mixing time. In the present embodiment, it is not necessary to calculate the uniform mixing time t by using the formulas (1) and (2) in the gas blowing step m As long as the resultant blowing time becomes the uniform mixing time t when the Ar gas is blown in m More than 1/4 of the total weight of the composition.
In the gas blowing step, the ladle 1 is moved from the drainage sand discharge position to the casting position where continuous casting is performed, while Ar gas is blown.
After the gas blowing step, a re-pouring step of pouring molten steel 4 from the ladle 1 is performed. In the re-pouring step, the ladle 1 is placed in the casting position, and the slide plate 32 is moved to the open position to open the slide gate device 3, whereby molten steel 4 is poured from the ladle 1 through the upper nozzle 2, the 1 st nozzle 311, the 2 nd nozzle 321, and the lower nozzle 33. Then, the poured molten steel 4 is continuously cast. The continuous casting method of the poured molten steel 4 may be a general method. For example, a long nozzle is connected to the lower nozzle 33, and the molten steel 4 poured out is poured into a tundish via the long nozzle, and further poured out from the tundish into a mold (die), thereby performing casting. As described above, in the present embodiment, the sliding gate valve device 3 is controlled as described above in the pouring step, the blowing step, and the re-pouring step. Next, by controlling the sliding gate valve device 3 by this control method, continuous casting is performed, and a cast piece having a predetermined cross-sectional shape corresponding to the mold is manufactured.
< modification >
The present invention has been described above with reference to specific embodiments, but the present invention is not limited to these descriptions. Other embodiments of the disclosed embodiments, as well as various variations of the invention, will be apparent to those skilled in the art upon reference to the description of the invention. Therefore, it should be understood that the embodiments of the invention described in the claims also include embodiments including these modifications described in the present specification, alone or in combination.
For example, in the above embodiment, the sliding gate valve device 3 is a 2-layer device having 2 plates, i.e., the upper plate 31 and the sliding plate 32, but the present invention is not limited to this example. For example, the sliding gate valve device 3 may be a 3-layer device as shown in fig. 5 and 6. The sliding gate valve apparatus 3 shown in fig. 5 and 6 includes an upper plate 31, a sliding plate 32, a lower plate 34, and a lower nozzle 33. The upper plate 31, the slide plate 32, and the lower nozzle 33 are the same as those of the above embodiment. The lower plate 34 is a plate made of a refractory material, and has a circular 3 rd nozzle hole 341 formed therein in the vertical direction. The lower plate 34 is fixedly provided on the lower surface of the slide plate 32 with respect to the upper plate 31, and is provided so as to overlap the 1 st nozzle 311 and the 3 rd nozzle 341 concentrically when viewed from the vertical direction. That is, in the sliding gate valve device 3 shown in fig. 5 and 6, the slide plate 32 is provided so as to be sandwiched between the upper plate 31 and the lower plate 34, and slides between the upper plate 31 and the lower plate 34. The lower nozzle 33 is fixedly provided on the lower surface of the lower plate 34, and the circular hole of the lower nozzle 33 and the 3 rd nozzle hole 341 are concentrically overlapped when viewed from the vertical direction. As shown in fig. 5, the gas blowing hole 322 is disposed between the 1 st nozzle 311 and the 3 rd nozzle 341, and the sliding gate valve 3 is closed, and as shown in fig. 6, the 2 nd nozzle 321 is disposed between the 1 st nozzle 311 and the 3 rd nozzle 341, and the sliding gate valve 3 is opened. Further, the sliding gate valve 3 is not limited to the above-described modification, and any sliding gate valve 3 may be used as long as it is provided in the ladle 1 and can perform gas bubbling in a closed state.
In the above embodiment, the description was given of the case of re-casting in the continuous casting apparatus, but the present invention is not limited to this example. For example, the apparatus for producing a cast slab may be not a continuous casting apparatus but an ingot casting apparatus for casting a steel ingot. In addition, regardless of the difference in the manufacturing facilities of the cast piece, the molten steel 4 may be poured for the purpose of normal casting, instead of pouring for the purpose of discharging the drainage sand 6 in the pouring step. For example, in an ingot casting facility, since the molten steel 4 may be transferred to a plurality of pouring pipes, a re-pouring operation may be performed when changing the pouring pipe to be transferred with the molten steel 4. In addition, in a continuous casting plant, casting may be temporarily interrupted due to a failure of the plant or the like, and in this case, a re-pouring operation may be performed. In these cases, as in the above embodiments, the blowing step is performed at the time of the re-pouring, and thus occurrence of non-perforation in the re-pouring step can be suppressed. Further, in order to suppress occurrence of non-tapping during such a casting interruption, the steel grade of the molten steel 4 is not limited to high-cleanliness steel, and any steel grade of the molten steel 4 can be suitably used.
Further, in the above embodiment, as the uniform mixing time t m The time calculated according to the formulas (1) and (2) is used, but the present invention is not limited to this example. Uniform mixing time t m The time required for the component concentration of the molten steel 4 to progress to a certain range around the final value may be a concept generally defined in the refining field. Therefore, the time calculated from the formulas other than the formulas (1) and (2) can be used as the homogeneous mixing time t m . For example, instead of the expression (2), an expression for the uniform mixing time may be used, which is a model of the shape of the ladle 1 that is closer to the actual shape.
In the above embodiment, the gas to be blown in the blowing step is Ar gas, but the present invention is not limited to this example. The gas to be blown in the blowing step may be an inert gas, or a gas other than Ar gas may be used.
Effect of the embodiments >
(1) The control method of the sliding gate valve device 3 according to one embodiment of the present invention is to provide a control method of a sliding gate valve device 3 which is installed in a ladle 1 from the ladle 1 containing molten steel 4 via a slide provided in the ladle 1A method for controlling a sliding gate valve device 3 for pouring molten steel 4 from a moving gate valve device 3, the sliding gate valve device 3 comprising: an upper plate 31 provided on a lower surface of an upper nozzle 2 fixed to a bottom of the ladle 1 and having a 1 st nozzle hole 311; and a slide plate 32 provided on a lower surface of the upper plate 31 and having a 2 nd nozzle hole 321, the slide plate 32 being configured to be movable in a range from an open position, in which at least a part of the 2 nd nozzle hole 321 overlaps the 1 st nozzle hole 311, to a closed position, in which the 2 nd nozzle hole 321 does not overlap the 1 st nozzle hole 311 and the 1 st nozzle hole 311 is blocked by the slide plate 32, by sliding the lower surface of the upper plate 31, the slide plate 32 further having a gas blowing hole 322 for blowing an inert gas into the 1 st nozzle hole 311 in the closed position, the control method comprising: a pouring step of pouring a part of molten steel 4 from the ladle 1 through the 1 st nozzle 311 and the 2 nd nozzle 321 by placing the slide plate 32 at an open position in a state where the ladle 1 accommodates the molten steel 4; a gas blowing step of moving the slide plate 32 to a closed position after the pouring step, and blowing inert gas from the gas blowing hole 322 to the molten steel 4 in the ladle 1 through the 1 st nozzle 311; and a re-pouring step of pouring molten steel 4 from the ladle 1 through the 1 st nozzle 311 and the 2 nd nozzle 321 by placing the slide plate 32 at an open position after the gas blowing step, wherein the blowing flow rate of the inert gas is set to 3.9Nm in the gas blowing step 3 /(min·m 2 ) Above and 26.0Nm 3 /(min·m 2 ) Hereinafter, the flow rate of the inert gas is the volume of the inert gas blown per unit time per the cross-sectional area of the nozzle hole of the nozzle 2.
According to the configuration of (1) above, the inflow of the molten steel 4 into the sliding gate valve 3 and the stagnation of the molten steel flow in the vicinity of the sliding gate valve 3 can be suppressed by the blowing of the inert gas, and the solidification of the molten steel 4 in the sliding gate valve 3 can be suppressed. This can prevent the occurrence of non-tapping during the re-pouring of the molten steel 4 in the ladle 1 (re-pouring step).
(2) In the configuration of (1) above, in the gas blowing step, the time for blowing the inert gas, that is, the blowing time, is set to 1/4 or more of the uniform mixing time of the molten steel 4 in the ladle 1 by stirring of the inert gas.
According to the configuration of (2), the temperature of the molten steel 4 in the ladle 1 can be made uniform by stirring the inert gas, and solidification of the molten steel 4 in the sliding gate valve apparatus 3 can be suppressed. This can further suppress occurrence of no open hole during the re-pouring of the molten steel 4 at the ladle 1 (re-pouring step).
(3) In the above configuration (2), in the gas blowing step, the blowing time is set to be the uniform mixing time t obtained from the formula (2) using the stirring power ε (W/t) of the formula (1) m More than 1/4 of(s).
According to the configuration of (3), the homogeneous mixing time can be calculated by a simple and highly accurate calculation model, and the blowing time can be calculated by a simple calculation method.
(4) In any one of the above configurations (1) to (3), in the pouring step, the pouring time, which is the time for pouring a part of the molten steel 4 from the ladle 1, is set to 5 seconds to 13 seconds.
According to the configuration of (4) above, the amount of molten steel 4 poured out necessary for heating the sliding gate valve 3 by the sensible heat of the poured molten steel 4 is provided, and solidification of the molten steel 4 in the sliding gate valve 3 can be suppressed. This can further suppress occurrence of non-tapping during the re-pouring of the molten steel 4 at the ladle 1 (re-pouring step) without significantly reducing the yield of the molten steel.
(5) In the method for producing a cast piece according to one embodiment of the present invention, in the method for producing a cast piece in which molten steel 4 is poured from a ladle 1 containing molten steel 4 through a sliding gate device 3 provided in the ladle 1 and the poured molten steel 4 is cast, the molten steel 4 poured in the re-pouring step is cast using the method for controlling the sliding gate device 3 according to any one of the above (1) to (4).
According to the configuration of (5) above, the same effects as those of the configurations of (1) to (4) above can be obtained. In particular, when casting high-cleanliness steel, which is a steel grade that must be cast with the guide sand 6 in the casting step of the above embodiment, the quality of the cast product and the casting yield can be improved.
Example 1
Next, example 1 by the present inventors will be described. In the examples, casting was performed by the method for manufacturing a cast piece according to the above embodiment, and the success rate of the hole forming in the re-casting step, that is, the re-forming success rate was examined.
In example 1, a molten steel 4 was used in an amount of 190t and a nozzle diameter of the upper nozzle 2 was 70mm (nozzle cross-sectional area 3.8X10) -3 m 2 ) Steel ladle 1 of (2) was investigated.
In example 1, in the pouring step, the slide plate 32 was placed at the open position for 7 seconds, and the drainage sand and the molten steel were poured out. After that, the slide plate 32 is returned to the closed position, and Ar gas is blown into the molten steel 4 in the ladle 1 from the gas blowing hole 322 via the 1 st nozzle 311. The flow rate of Ar gas was set to 30.0NL/min (7.8 Nm) 3 /(min·m 2 ))。
On the other hand, as a comparison, in the pouring step, a case was examined in which after the slide plate 32 was placed at the open position for 3 seconds and the sand and molten steel were poured, the slide plate 32 was returned to the closed position, and 30.0NL/min of Ar gas was blown into the molten steel 4 in the ladle 1 from the gas blowing hole 322 through the 1 st nozzle 311 (comparative example 1-1). In addition, a case was examined in which after the slide plate 32 was left in the open position for 7 seconds and the drainage sand and the molten steel were poured out, the slide plate 32 was returned to the closed position, and 10.0NL/min of Ar gas was blown into the molten steel 4 in the ladle 1 from the gas blowing hole 322 via the 1 st nozzle 311 (comparative examples 1-2). Further, in the pouring step, after the slide plate 32 was left at the open position for 14 seconds and the drainage sand and the molten steel were poured out, the slide plate 32 was returned to the closed position, and 30.0NL/min of Ar gas was blown into the molten steel 4 in the ladle 1 from the gas blowing hole 322 through the 1 st nozzle 311 (comparative examples 1 to 3).
As a result of the investigation, although the hole could be opened without any problem in the reflow step under the conditions of example 1, no hole was formed in comparative examples 1-1 and 1-2. The ladles of comparative examples 1-1 and 1-2 were not subjected to forced tapping treatment by oxygen purging, and the molten steel in the ladle was transferred to a lining for a converter to become an empty ladle. After cooling, the sliding gate valve apparatus 3 was examined, and as a result, it was found that the ladles of comparative examples 1-1 and 1-2 were each clogged with solidified steel in the upper nozzle. In contrast to the fact that the tapping was performed in the re-pouring step under the conditions of comparative examples 1 to 3, the amount of molten steel actually cast was 99.5% under the conditions of example 1, and the amount of molten steel actually cast was reduced to 98.9% under the conditions of comparative examples 1 to 3.
Example 2
In example 2, the homogeneous mixing time under the conditions of the actual machine was calculated before investigation. As a condition for calculation, the temperature T of the molten steel 4 is set 1 1827 (K), and 190t and h are the weight W of the molten steel 4, respectively v Set to 2.29m, the atmosphere pressure P a Setting the standard state temperature T to 0.1MPa 0 Set to 300K, set the bath diameter d v Set to 3.375m. The calculation results are shown in fig. 7. As shown in fig. 7, it was confirmed that when the flow rate of Ar gas blown in under the conditions of the actual equipment was 30.0NL/min, the uniform mixing time was 1/4 of 61.0s.
Next, in example 2, based on the above results, continuous casting of molten steel was performed with 1/4 of the homogeneous mixing time set to 61.0s, and the re-tapping success rate was examined. In example 2, continuous casting of molten steel 4 was performed under the same conditions as those under which 1/4 of the homogeneous mixing time was calculated, and Ar gas was blown in at a blowing flow rate of 30.0NL/min in the blowing step. In addition, in example 2, as a comparison, continuous casting was also performed under the condition that the blowing time was less than 61.0s, that is, less than 1/4 of the homogeneous mixing time, and the re-tapping success rate was examined (comparative example 2).
Fig. 8 shows the results of the re-opening success rate in example 2 and comparative example 2. As shown in fig. 8, in comparative example 2 in which the blowing time was less than 61.0s, the re-opening ratio was 75.0% (12 times of successful hole opening/16 times of casting execution) and was low. In contrast, in the case of example 2 in which the blowing time was 61.0s or longer, the reopening rate was 93.8% (30 times after successful hole forming/32 times after casting), and it was confirmed that the reopening rate was greatly improved.
Description of the reference numerals
1. Ladle
2. Upper nozzle
3. Sliding gate valve device
31. Upper plate
311. 1 st spray hole
32. Sliding plate
321. 2 nd spray hole
322. Gas blowing hole
33. Lower nozzle
34. Lower plate
341. 3 rd spray hole
4. Molten steel
5. Slag of furnace
6. Drainage sand
Claims (4)
1. A control method of a sliding gate valve apparatus for pouring molten steel from a ladle containing molten steel through a sliding gate valve apparatus provided in the ladle,
the sliding gate valve device has: an upper plate provided at a lower surface of an upper nozzle fixed at a bottom of the ladle, the upper plate having a 1 st nozzle hole; and a sliding plate provided on a lower surface of the upper plate, the sliding plate having a 2 nd nozzle,
the slide plate is configured to be movable in a range from an open position, in which at least a part of the 2 nd nozzle hole overlaps the 1 st nozzle hole, to a closed position, in which the 2 nd nozzle hole does not overlap the 1 st nozzle hole and the 1 st nozzle hole is blocked by the slide plate, by sliding the slide plate on the lower surface of the upper plate, the slide plate further having a gas blowing hole for blowing an inert gas into the 1 st nozzle hole in the closed position,
the control method of the sliding gate valve device comprises the following steps:
a pouring step of placing the slide plate at the open position in a state where the ladle contains the molten steel, and pouring a part of the molten steel from the ladle through the 1 st nozzle and the 2 nd nozzle;
a gas blowing step of moving the slide plate to the closed position after the pouring step, and blowing the inert gas from the gas blowing hole to the molten steel in the ladle through the 1 st nozzle hole; and
a pouring step of pouring the molten steel from the ladle through the 1 st nozzle and the 2 nd nozzle by placing the slide plate at the open position after the gas blowing step,
in the gas blowing step, the flow rate of the inert gas is set to 3.9Nm 3 /(min〃m 2 ) Above and 26.0Nm 3 /(min〃m 2 ) The flow rate of the inert gas is a volume of the inert gas blown into the upper nozzle per unit time for a unit nozzle hole cross-sectional area,
in the gas blowing step, the time for blowing the inert gas, that is, the blowing time, is 1/4 or more of the time for uniformly mixing the molten steel in the ladle by stirring the inert gas.
2. The control method of a sliding gate valve apparatus according to claim 1, wherein,
in the gas blowing step, the blowing time is set to be a uniform mixing time t obtained from the formula (2) using the stirring power ε (W/t) of the formula (1) m More than 1/4 of(s),
[ mathematics 1]
Epsilon: stirring power (W/t)
V g : flow rate (Nm) of inert gas 3 /min)
T 1 : temperature of molten steel (K)
W: weight of molten steel (t)
P a : atmospheric pressure (Pa)
T 0 : standard temperature (K)
h v : bath depth (m)
d v : bath diameter (m).
3. The control method of a sliding gate valve apparatus according to claim 1 or 2, wherein,
in the pouring step, a pouring time, which is a time for pouring a part of the molten steel from the ladle, is set to be 5 seconds to 13 seconds.
4.A method for producing a cast piece, wherein molten steel is poured from a ladle containing molten steel through a sliding gate valve provided in the ladle, the poured molten steel is cast,
the method of controlling a sliding gate valve according to any one of claims 1 to 3, wherein the molten steel poured in the re-pouring step is cast.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2019014592 | 2019-01-30 | ||
| JP2019-014592 | 2019-01-30 | ||
| PCT/JP2020/001590 WO2020158465A1 (en) | 2019-01-30 | 2020-01-17 | Method for controlling sliding nozzle device, and method for manufacturing slab |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113365759A CN113365759A (en) | 2021-09-07 |
| CN113365759B true CN113365759B (en) | 2023-07-25 |
Family
ID=71841076
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202080011512.1A Active CN113365759B (en) | 2019-01-30 | 2020-01-17 | Control method of sliding gate valve device and manufacturing method of cast piece |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP6733854B1 (en) |
| CN (1) | CN113365759B (en) |
| WO (1) | WO2020158465A1 (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1200384A (en) * | 1982-04-22 | 1986-02-11 | Francis L. Kemeny, Jr. | Ladle slide gate collector nozzle |
| JP2002346707A (en) * | 2001-05-25 | 2002-12-04 | Nkk Corp | Continuous casting method of steel |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3809146A (en) * | 1972-02-18 | 1974-05-07 | Steel Corp | Method of opening an intermediate vessel nozzle for continuous casting |
| FR2490123A1 (en) * | 1980-09-15 | 1982-03-19 | Air Liquide | PLATE SHUTTER DEVICE FOR CONTAINER CASTING HOLES CONTAINING A FUSION METAL |
| JPH06218530A (en) * | 1993-01-22 | 1994-08-09 | Nippon Steel Corp | Closing method of sliding type molten metal pouring device |
| JPH0947862A (en) * | 1995-08-03 | 1997-02-18 | Nkk Corp | Device for boring pouring hole of molten metal and method therefor |
| JP2000202599A (en) * | 1999-01-06 | 2000-07-25 | Nkk Corp | Continuous casting method |
| CN101745630A (en) * | 2008-12-19 | 2010-06-23 | 鞍钢重型机械有限责任公司 | Method for pouring cast part |
| JP2012161830A (en) * | 2011-02-09 | 2012-08-30 | Jfe Steel Corp | Method for opening sliding type opening/closing device of ladle |
| JP5831163B2 (en) * | 2011-11-21 | 2015-12-09 | Ｊｆｅスチール株式会社 | Manufacturing method of high cleanliness steel |
| CN102784908A (en) * | 2012-08-30 | 2012-11-21 | 南京钢铁集团冶金铸造有限公司 | Non-drainage pouring technology for steel ladle |
| CN103008588B (en) * | 2013-01-09 | 2014-12-10 | 河北联合大学 | Nozzle slag line erosion resistant device and method for protecting pouring by using same |
| JP6187773B2 (en) * | 2014-10-14 | 2017-08-30 | Ｊｆｅスチール株式会社 | Sliding nozzle device for molten metal holding container and method for pouring molten metal from this device |
| JP2017177109A (en) * | 2016-03-28 | 2017-10-05 | 株式会社神戸製鋼所 | Injection starting method of molten steel when starting continuous casting |
| CN108555273B (en) * | 2018-06-04 | 2020-03-31 | 东北大学 | Method for improving ladle self-opening rate by bottom blowing inert gas |
| CN109128125A (en) * | 2018-10-30 | 2019-01-04 | 马鞍山钢铁股份有限公司 | A kind of Con casting ladle is without drainage casting apparatus and without drainage method for pouring |
-
2020
- 2020-01-17 JP JP2020520082A patent/JP6733854B1/en active Active
- 2020-01-17 WO PCT/JP2020/001590 patent/WO2020158465A1/en active Application Filing
- 2020-01-17 CN CN202080011512.1A patent/CN113365759B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1200384A (en) * | 1982-04-22 | 1986-02-11 | Francis L. Kemeny, Jr. | Ladle slide gate collector nozzle |
| JP2002346707A (en) * | 2001-05-25 | 2002-12-04 | Nkk Corp | Continuous casting method of steel |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2020158465A1 (en) | 2020-08-06 |
| JP6733854B1 (en) | 2020-08-05 |
| CN113365759A (en) | 2021-09-07 |
| JPWO2020158465A1 (en) | 2021-02-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| RU2675880C2 (en) | Semi-continuous casting of a steel strip | |
| CN113365759B (en) | Control method of sliding gate valve device and manufacturing method of cast piece | |
| JP6154708B2 (en) | Continuous casting method | |
| JP5082700B2 (en) | Steel continuous casting method | |
| KR101239537B1 (en) | Method for deceasing a depression of strip surface by optimization a deposition depth in submerged entry nozzle | |
| JP2891270B2 (en) | Spontaneous opening method of water pool in tundish | |
| CN111842819A (en) | Ingot mold casting device based on flow field control and using method thereof | |
| JP2005103552A (en) | Continuous casting method | |
| JP6188642B2 (en) | Bottom pouring method | |
| KR101969113B1 (en) | Apparatus for treating molten metal | |
| JP2013508162A (en) | Method of manufacturing a metal ingot including a bore and related ingot and forming apparatus | |
| JPH09239501A (en) | Method for refining molten steel in tundish | |
| JP2013508162A5 (en) | ||
| JP2010269359A (en) | Method of hot reusing tundish focusing on temperature difference between precedent charge and subsequent charge | |
| JP5076693B2 (en) | Continuous casting tundish and steel continuous casting method | |
| JP6837179B1 (en) | Tandish nozzle for continuous casting of steel | |
| JP7172003B2 (en) | Operation method of waste water | |
| JPH0938756A (en) | Method for starting casting in continuous casting | |
| Dutta et al. | Continuous casting (concast) | |
| JPH0133271B2 (en) | ||
| JP4289476B2 (en) | High cleanliness steel casting method | |
| KR200184910Y1 (en) | Apparatus for preventing the inflow of slag into the mold in the continuously casting machine | |
| JP2021169123A (en) | Method for casting molten metal utilizing impact pad for tundish | |
| JPH0292442A (en) | Method for preventing nozzle clogging in continuous casting for molten steel | |
| JPH08276261A (en) | Ladle and method for opening ladle nozzle |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |