A method for quickly changing tundish in a large round billet casting machine

Abstract

The present invention discloses a method for quickly changing tundishes in a large round billet casting machine, including: optimizing the process flow: after the old tundish is finished pouring, it is transported away from the pouring position, and at the same time, the new tundish is transported to the pouring position, and the two tundish cars are running at the same time. During the centering process of the submerged nozzle, the ladle is rotated to the top of the tundish in the pouring position to wait for pouring to start, in order to save waiting time; scientifically shortening the quick-changing process: utilizing the slow solidification property of the liquid core of the large round billet, the new and old billets are connected by liquid core solidification; at the end of pouring, the casting machine maintains a relatively high pulling speed, and increases the shrinkage cavity depth to ensure that the liquid cores of the new and old billets are fully bonded. The purpose of the present invention is to provide a method for quickly changing tundishes in a large round billet casting machine, aiming to solve the technical problems of the traditional tundish replacement method, such as complex operation and long time consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of continuous casting, in particular to a process method for quickly changing a tundish of a large round billet casting machine. Background Art

[0002] Continuous casting technology involves the continuous pouring, cooling, and solidification of molten steel into billets of various specifications. During the continuous casting process, the tundish, the primary storage device for the molten steel, directly impacts production efficiency and product quality. Traditional tundish replacement methods are complex and time-consuming, and are no longer sufficient to meet the demands of modern continuous casting.

[0003] After searching, we found three documents and patents that are most relevant to the present invention. The specific contents are described as follows:

[0004] After searching, similar background technologies include: "A method for quick-changing tundishes in a continuous casting machine" (patent application number: CN202210278936.5). The difference between this patent and the present invention is that the quick-changing method of this patent does not use connectors to connect the new and old billets, while the quick-changing method of the similar patent searched does use connectors to connect the new and old billets, and the process methods are different;

[0005] After searching, similar background technologies include: "A method for quickly replacing the online tundish of an ultra-wide thin slab continuous casting machine" (patent application number: CN202210355945.X). The difference from the present invention is that: the patent mainly involves an ultra-wide thin slab continuous casting machine, while the present patent is a large round billet casting machine with different production processes;

[0006] After searching, similar background technologies include: "A method for reducing the time of quick-changing tundish in a dual-strand large slab continuous casting machine" (patent application number: CN202211485159.8). The difference from the present invention is that: this patent mainly involves large round billet casting machines, while the similar patents retrieved involve slab continuous casting machines, and the production processes are different. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for quickly changing the tundish of a large round billet casting machine, aiming to solve the problems of the traditional tundish replacement method, which is complicated to operate and time-consuming (see Figure 1 , it takes 12-15 minutes to replace the tundish) and other technical issues.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for quickly changing a tundish of a large round billet casting machine, comprising:

[0010] Optimize the process flow: After the old tundish is finished pouring, it is transported away from the pouring position, and the new tundish is transported to the pouring position at the same time. The two tundish cars are running at the same time. During the submerged nozzle alignment process, the ladle is rotated to the top of the tundish in the pouring position and waits for pouring to start, in order to save waiting time.

[0011] Scientifically shorten the quick-change process: take advantage of the slow solidification of the liquid core of the large round billet and connect the new and old billets by liquid core solidification; at the end of pouring, the casting machine maintains a high pulling speed to increase the shrinkage cavity depth to ensure sufficient bonding of the liquid cores of the new and old billets; with this method, the shrinkage cavity depth of the tail billet is larger than the surface area, the center is the molten liquid steel billet shell, and the shrinkage of the tail billet is small, so there is almost no gap between the tail billet and the crystallizer wall, and there is no need to sprinkle iron filings to seal it.

[0012] Further, specifically including:

[0013] The large round billet casting machine has a quick-change tundish. At the end of the casting, when pouring the residual molten steel in the tundish, the casting machine is operated at a casting speed of 0.45-0.55m / min to form a deeper shrinkage cavity in the tail billet.

[0014] When the residual molten steel in the tundish reaches 200mm, close the stopper and stop pouring;

[0015] The old trolley is lifted and moved, and as the trolley moves, the tail billets of each stream are pulled to 450mm from the top of the crystallizer to wait for pouring;

[0016] While the old tundish car is lifted and moved away from the pouring position, the new tundish car moves from the preheating position to the pouring position. After the tundish arrives at the pouring position, the submerged nozzle is aligned with the crystallizer. At the same time, the ladle is rotated to the pouring position and waits for pouring to start. The baked tundish is lowered to the pouring position and the ladle starts pouring.

[0017] When the molten steel in the tundish reaches a certain level, the stopper rod is opened to inject new molten steel into the crystallizer. At this time, the core of the tail billet is still liquid molten steel. After the new molten steel is injected, the new and old molten steel are fused in the tail billet before the tundish is replaced. After the billet solidification time reaches 150-180 seconds, the straightening machine is started and the joint of the new and old billets is pulled out of the crystallizer at a pulling speed of 0.18-0.22m / min. Then, the appropriate billet pulling speed is matched according to the superheat of the molten steel.

[0018] Furthermore, the large round bloom casting machine quickly changes the tundish, and at the end of the casting, when pouring the residual molten steel in the tundish, the casting machine produces at a casting speed of 0.5m / min.

[0019] Furthermore, when the molten steel in the middle ladle reaches 12t, the stopper rod is opened to inject new molten steel into the crystallizer. At this time, the core of the tail billet is still liquid molten steel. After the new molten steel is injected, the new and old molten steel are fused in the tail billet before the middle ladle is replaced. After the billet solidification time reaches 150-180 seconds, the straightening machine is started and the joint of the new and old billets is pulled out of the crystallizer at a pulling speed of 0.2m / min. Then, the appropriate billet pulling speed is matched according to the superheat of the molten steel.

[0020] Furthermore, the time required to complete a quick tundish change on a casting machine can be controlled within 7 minutes, enabling rapid tundish replacement.

[0021] Furthermore, the quick change of the first furnace lowers the temperature by 20 degrees, reduces the power consumption of refining, and saves the cost per ton of steel.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] The casting machine quick-change process has been shortened, saving an average of 7 minutes per tundish change and increasing the casting machine's operating rate by 1.08%. The quick-change process lowers the temperature of the first furnace by 20°C, reducing refining power consumption and saving steel production costs per ton. The deformation of the slabs at the joints between the head and tail slabs has been reduced, resulting in an average reduction of 5 tons of scrapped slabs per quick-change operation. Through process improvements, the use of five connectors has been reduced per quick-change operation, lowering production costs.

[0024] The casting machine quickly changes the tundish, and the new and old billets are connected by liquid core fusion and solidification, which changes the original method of connecting the new and old billets using connecting parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings.

[0026] Figure 1 This is the process flow chart of the traditional quick-change tundish;

[0027] Figure 2 This is a process flow chart of the quick-change tundish of the present invention;

[0028] Figure 3 This is a schematic diagram of the traditional quick-change tundish casting connection;

[0029] Figure 4 This is a schematic diagram of the connection of the casting blank of the present invention;

[0030] Figure 5 This is a photo of the severe deformation of the billet at the connection between the new and old billets in the traditional quick-change tundish;

[0031] Figure 6 The present invention avoids deformation of the connection between the new and old billets and reduces billet cutting waste.

[0032] Figure 7 This is the vertical flow chart of the quick-change tundish of the casting machine. DETAILED DESCRIPTION

[0033] The present invention provides a method for quick replacement of tundishes for continuous casting of large round billets, aiming to solve the problems of complicated operation and long time consumption in traditional tundish replacement methods (see Figure 1 , it takes 12-15 minutes to replace the tundish once) and other technical problems. The technical solutions adopted are as follows:

[0034] 1. Optimize the process flow: When the old tundish is finished pouring, it is moved away from the pouring station, while the new tundish is transported to the pouring station. Both tundish cars operate simultaneously. During the submerged nozzle centering process, the ladle is rotated to the top of the tundish in the pouring station to wait for pouring to begin. This reduces waiting time.

[0035] 2. Scientifically reduce the quick change process: ① A method for connecting the new and old billets without connectors is designed. This method uses the slow solidification of the liquid core of the large round billet to connect the new and old billets by liquid core solidification; ② At the end of the pouring process, the casting machine maintains a high casting speed to increase the shrinkage cavity depth to ensure that the liquid cores of the new and old billets are fully bonded. ③ This method has a larger shrinkage cavity depth than the surface area of ​​the tail billet. The center is the molten liquid steel billet shell with small shrinkage. There is almost no gap between the tail billet and the crystallizer wall, and there is no need to sprinkle iron chips to block it. Through this patented technical solution ( Figure 2 ), the time for completing a quick tundish change on the casting machine can be controlled within 7 minutes. This enables rapid replacement of the tundish.

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention.

[0037] A method for quickly changing a tundish on a large round billet casting machine comprises: quickly changing the tundish on the large round billet casting machine; at the end of a casting cycle, when pouring the residual molten steel in the tundish, the casting machine operates at a pulling speed of 0.5 m / min to form a deeper shrinkage cavity in the tail billet; when the residual molten steel in the tundish remains at 200 mm, the stopper rod is closed and pouring is stopped; the old tundish car is lifted and moved, and as the tundish car moves, the tail billets of each stream are pulled to 450 mm from the upper mouth of the crystallizer to wait for pouring to start; while the old tundish car is lifted and moved away from the pouring position, the new tundish car moves from the preheating position to the pouring position; after the tundish reaches the pouring position, the submerged nozzle is aligned with the crystallizer, and the ladle is rotated to the pouring position to wait for pouring to start. , lower the baked tundish to the pouring position, and start pouring; when the molten steel in the tundish reaches 12 tons, open the stopper rod to inject new molten steel into the crystallizer. At this time, the core of the tail billet (the tail billet before changing the tundish) is still liquid steel. After the new molten steel is injected, the new and old molten steel are fused in the tail billet before changing the tundish. After the solidification time of the billet reaches 150-180 seconds, start the straightening machine and pull the joint of the new and old billets out of the crystallizer at a pulling speed of 0.2m / min. Then, match the appropriate billet pulling speed according to the superheat of the molten steel.

[0038] like Figure 4 As shown in the figure, the casting machine quickly changes the old and new castings by using the liquid core solidification connection method, which changes the original Figure 3 The new and old ingots are connected using connecting pieces.

[0039] The deformation of the casting billet at the connection between the new and old casting billets in the traditional quick-change tundish is serious, such as Figure 5As shown in the figure, each quick change of the billet waste is large. The process of the present invention avoids deformation of the connection between the new and old billets and reduces the billet waste. Figure 6 shown.

[0040] The method for efficient tundish quick change for continuous casting large round billets of the present invention has the following advantages and innovations:

[0041] Advantages: ①. Shortened casting machine quick-change time, saving an average of 7 minutes per tundish change and increasing casting machine availability by 1.08%. ②. Quick-change of the first furnace lowered the temperature by 20°C, reducing refining power consumption and saving per-ton steel costs. ③. Reduced and minimized slab deformation at the head and tail slab joints, reducing 5 tons of scrap per quick-change. ④ Through process improvements, the average number of connectors used per quick-change was reduced by five, lowering production costs.

[0042] Innovation: The casting machine quickly changes the tundish, and the new and old billets are connected by liquid core fusion and solidification, which changes the original method of connecting the new and old billets using connecting parts.

[0043] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for quickly changing the tundish of a large round billet casting machine, characterized in that: include: Optimize the process flow: After the old tundish is finished pouring, it is transported away from the pouring position, and the new tundish is transported to the pouring position at the same time. The two tundish cars are running at the same time. During the submerged nozzle alignment process, the ladle is rotated to the top of the tundish in the pouring position and waits for pouring to start, in order to save waiting time. Scientifically shorten the quick-change process: Utilizing the slow solidification of the liquid core of the large round billet, the new and old billets are connected by liquid core solidification. At the end of the pouring process, the casting machine maintains a high casting speed to increase the shrinkage cavity depth to ensure sufficient bonding of the liquid cores of the new and old billets. This method results in a larger shrinkage cavity depth than the surface area of ​​the tail billet, and the center of the molten liquid steel billet shrinks less, resulting in a virtually seamless gap between the tail billet and the crystallizer wall, eliminating the need for iron filings to seal. Specifically include: The large round billet casting machine has a quick-change tundish. At the end of the casting, when pouring the residual molten steel in the tundish, the casting machine is operated at a casting speed of 0.45-0.55m / min to form a deeper shrinkage cavity in the tail billet. When the residual molten steel in the tundish reaches 200mm, close the stopper and stop pouring; The old trolley is lifted and moved, and as the trolley moves, the tail billets of each stream are pulled to 450mm from the top of the crystallizer to wait for pouring; While the old tundish car is lifted and moved away from the pouring position, the new tundish car moves from the preheating position to the pouring position. After the tundish arrives at the pouring position, the submerged nozzle is aligned with the crystallizer. At the same time, the ladle is rotated to the pouring position and waits for pouring to start. The baked tundish is lowered to the pouring position and the ladle starts pouring. When the molten steel in the tundish reaches a certain level, the stopper rod is opened to inject new molten steel into the crystallizer. At this time, the core of the tail billet is still liquid molten steel. After the new molten steel is injected, the new and old molten steel are fused in the tail billet before the tundish is replaced. After the billet solidification time reaches 150-180 seconds, the straightening machine is started and the joint of the new and old billets is pulled out of the crystallizer at a pulling speed of 0.18-0.22m / min. Then, the appropriate billet pulling speed is matched according to the superheat of the molten steel.

2. The method for quickly changing the tundish of a round bloom casting machine according to claim 1, characterized in that: The large round billet casting machine quickly changes the tundish. At the end of the casting, when pouring the residual molten steel in the tundish, the casting machine produces at a pulling speed of 0.5m / min.

3. The method for quickly changing the tundish of a round bloom casting machine according to claim 1, characterized in that: When the molten steel in the tundish reaches 12t, the stopper rod is opened to inject new molten steel into the crystallizer. At this time, the core of the tail billet is still liquid steel. After the new molten steel is injected, the new and old molten steel are fused in the tail billet before the tundish is replaced. After the billet solidification time reaches 150-180 seconds, the straightening machine is started and the joint of the new and old billets is pulled out of the crystallizer at a pulling speed of 0.2m / min. Then, the appropriate billet pulling speed is matched according to the superheat of the molten steel.

4. The method for quickly changing the tundish of a round bloom casting machine according to claim 1, characterized in that: The time required to complete a quick tundish change on a casting machine can be controlled within 7 minutes, enabling rapid replacement of the tundish.

5. The method for quickly changing the tundish of a round bloom casting machine according to claim 1, characterized in that: The quick change of the first furnace lowers the temperature by 20 degrees, reduces the power consumption of refining, and saves the cost per ton of steel.

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