Method and system for maintaining tundish molten steel level during automatic pouring of casting machine

Abstract

The present invention discloses a method and system for maintaining the liquid level of molten steel in a middle ladle during the automatic pouring process of a casting machine. In the automatic pouring state of the casting machine, the molten steel in a large ladle flows into the middle ladle through the large ladle water inlet, and the molten steel in the middle ladle flows into the crystallizer through the middle ladle water inlet. The opening of the large ladle water inlet V z Influence of the molten steel flow rate Q flowing into the tundish z , Tundish water inlet opening V m Influence of molten steel flow rate Q flowing into the crystallizer m , the molten steel flow rate Q flowing into the tundish z The molten steel flow rate Q flowing into the crystallizer m Jointly determine the weight of molten steel in the tundish W z By controlling the opening of the ladle nozzle V z The weight of molten steel in the tundish is W z The present invention controls the opening of the ladle nozzle to maintain the molten steel level in the middle ladle, thereby ensuring the consistency of the process parameters of each casting strand and increasing the success rate of automatic casting of the casting machine.

Description

Technical Field

[0001] The invention belongs to the technical field of steelmaking continuous casting process in the metallurgical industry, and particularly relates to a method and system for maintaining the liquid level of molten steel in a tundish during the automatic pouring process of a casting machine. Background Art

[0002] Automatic pouring technology is widely used in the metallurgical steelmaking and continuous casting industry. Almost every step in this technology involves controlling the flow rate of steel flowing into the mold. Flow rate is generally controlled by the tundish nozzle opening: a larger opening increases flow rate, and vice versa. Furthermore, the flow rate into the mold is not only affected by the tundish nozzle opening, but also by the molten steel level within the tundish. For a given opening, a higher tundish steel level increases flow rate, and vice versa. The tundish steel level is generally not directly measurable; currently, it is mostly measured indirectly through the weight of the tundish: the heavier the tundish, the higher the level, and vice versa.

[0003] Currently, the parameters such as the steel flow rate and time flowing into the crystallizer corresponding to the opening of the tundish water inlet in the established steps of automatic pouring are mostly derived from production practice. Once the actual steel flow rate flowing into the crystallizer deviates too much from the set value, the established steps of automatic pouring cannot be guaranteed to be completed, which reduces the success rate of automatic pouring.

[0004] The number of strands contained in a single casting machine varies depending on the type of continuous casting machine. Currently, most casting machines' automatic pouring technology solutions do not pour all strands simultaneously, but rather pour them gradually, one after the other. Furthermore, the opening parameters in the automatic pouring steps rarely take into account changes in the weight of the tundish molten steel. When the number of strands on a casting machine is small and the time interval between the pouring of the first and last strands is short, the weight change of the tundish molten steel is relatively small, barely meeting production needs. However, as the number of strands on a casting machine increases, the time it takes to pour all strands is increasing. As the pouring time increases, the actual molten steel level in the tundish molten steel also increases. The actual deviation between the actual flow rate of the strands poured in the late stages and the set flow rate into the crystallizer is too large, significantly reducing the success rate of automatic pouring. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for maintaining the molten steel level in the middle ladle during the automatic pouring process of a casting machine, and a system for maintaining the molten steel level in the middle ladle during the automatic pouring process of a casting machine based on the above method. The molten steel level in the middle ladle is maintained by controlling the opening of the large ladle water inlet, thereby ensuring the consistency of the casting process parameters of each casting strand, thereby increasing the success rate of the automatic pouring of the casting machine.

[0006] The technical solution adopted in the present invention is:

[0007] A method for maintaining the molten steel level in the middle ladle during the automatic pouring process of the casting machine. When the casting machine is in the automatic pouring state, the molten steel in the large ladle flows into the middle ladle through the large ladle water inlet, and the molten steel in the middle ladle flows into the crystallizer through the middle ladle water inlet. The opening of the large ladle water inlet is V z Influence of the molten steel flow rate Q flowing into the tundish z , Tundish water inlet opening V m Influence of molten steel flow rate Q flowing into the crystallizer m , the molten steel flow rate Q flowing into the tundish z The molten steel flow rate Q flowing into the crystallizer m Jointly determine the weight of molten steel in the tundish W z By controlling the opening of the ladle nozzle V z Make the weight of molten steel in the tundish W z Maintain it within a certain range to keep the molten steel level in the tundish.

[0008] Preferably, before the casting machine starts automatically pouring, the molten steel in the large ladle flows into the middle ladle through the large ladle water inlet, and the weight of the molten steel in the middle ladle is W z Gradually increase from zero until the weight of molten steel in the tundish is W z When the level increases to meet the automatic pouring requirement, the automatic pouring state is entered. The casting strand is gradually poured according to the process rules, and the number of cast strands that have been poured is counted n. When n≥n2, the tundish steel liquid level is maintained and the time t is set. By controlling the opening of the ladle nozzle V z Make the weight of molten steel in the tundish W z Maintain within a certain range, thereby maintaining the tundish molten steel level. Then, as the pouring proceeds normally, until n≥n1 and the delay is t2, the tundish molten steel level maintenance working condition is exited and the timer t is reset to zero. The tundish molten steel weight W z Increase to normal production process parameters, and the casting machine enters normal production; among them, n2 is the setting parameter for the number of opened casting streams when starting the tundish steel molten level maintenance condition, n1 is the setting parameter for the number of opened casting streams when stopping the tundish steel molten level maintenance condition, and t2 is the setting parameter for the delay time after reaching the set number of opened casting streams under the tundish steel molten level maintenance condition.

[0009] Preferably, after entering the tundish steel liquid level maintenance working condition and timing t, when n<n1 and t>t1, the tundish steel liquid level maintenance working condition is exited and timing t is reset to zero, and the tundish steel liquid weight W z Increase to normal production process parameters, and the casting machine enters normal production; among them, t1 is the setting parameter of the timeout time under the condition of maintaining the tundish molten steel level.

[0010] Preferably, for a billet casting machine with a large number of strands, the molten steel flow rate Q flowing into the tundish is z Much larger than the molten steel flow rate Q flowing into the crystallizer m By setting a larger n2, the opening of the water outlet of the large ladle can be reduced. zcontrol difficulty.

[0011] Preferably, the casting machine includes a slab casting machine, a bloom casting machine, and a billet casting machine.

[0012] A system for maintaining the molten steel level in a middle ladle during the automatic pouring process of a casting machine comprises a ladle shroud opening adjustment mechanism, a molten steel weight monitoring mechanism in a middle ladle, and a controller. The controller adopts the above-mentioned method for maintaining the molten steel level in a middle ladle during the automatic pouring process of a casting machine as a control strategy, and can control the ladle shroud opening adjustment mechanism to adjust the molten steel opening of the large ladle according to the molten steel weight in the middle ladle fed back by the molten steel weight monitoring mechanism.

[0013] The beneficial effects of the present invention are:

[0014] The present invention controls the opening of the ladle nozzle V in the automatic pouring state. z The tundish molten steel level is maintained in this way, so that the casting machine can maintain the same tundish water inlet opening V regardless of whether it is the casting stream in the early stage or the casting stream in the later stage. m The corresponding molten steel flow rate Q into the crystallizer m Convergence ensures the consistency of each casting process parameter, thereby increasing the success rate of automatic casting of the casting machine; Among them, the weight of the molten steel in the tundish W z There is a small fluctuation within a certain range. This fluctuation has a great impact on the flow rate Q of the molten steel flowing into the crystallizer. m The impact can be neglected. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the steel flow path when the casting machine starts pouring.

[0016] In the figure: 1-large bag; 2-large bag water outlet; 3-medium bag; 4-medium bag water outlet; 5-crystallizer. DETAILED DESCRIPTION

[0017] The present application will be further described below with reference to the accompanying drawings and examples.

[0018] Example 1

[0019] This embodiment provides a method for maintaining the molten steel level in the ladle during the automatic pouring process of the casting machine: when the casting machine is in the automatic pouring state, Figure 1 As shown, the molten steel in ladle 1 flows into the tundish through the ladle inlet 2, and the molten steel in the tundish 3 flows into the crystallizer 5 through the tundish inlet 4. The opening of the ladle inlet 2 is V z Influence of the molten steel flow rate Q flowing into the tundish 3 z (V z Increase Q z Increase, vice versa), the opening of the tundish water inlet 4 is V m Affects the molten steel flow rate Q flowing into the crystallizer 5 m (V m Increase Qm Increase, and vice versa), the molten steel flow rate Q flowing into the tundish 3 z The molten steel flow rate Q flowing into the crystallizer 5 m Jointly determine the weight of molten steel in tundish 4, W z (Q z >Q m Time W z Increase, and vice versa), by controlling the opening V of the large ladle nozzle 2 z Make the weight of molten steel in the tundish 3 W z Maintain within a certain range, thereby maintaining the molten steel level of the middle ladle 3. This method controls the opening V of the large ladle nozzle 2 in the automatic pouring state. z The way to maintain the molten steel level in the tundish 3 is to make the casting machine, whether it is the casting stream of the early casting or the casting stream of the later casting, the same tundish water inlet 4 opening V m The corresponding molten steel flow rate Q flowing into the crystallizer 5 m Convergence ensures the consistency of each casting process parameter, thereby increasing the success rate of automatic casting of the casting machine; Among them, the weight of molten steel in the middle package 3 W z There is a small fluctuation within a certain range. This fluctuation has an impact on the flow rate Q of the molten steel flowing into the crystallizer 5. m The impact can be neglected.

[0020] The specific process of this method is: before the casting machine starts automatically pouring, the molten steel in the large ladle 1 flows into the middle ladle 3 through the large ladle water inlet 2. The weight of the molten steel in the middle ladle 3 is W z Gradually increase from zero until the weight of molten steel in the tundish 3 is W z When the automatic pouring is satisfied, the automatic pouring state is entered; then the casting strand is gradually poured according to the process rules, and the number of cast strands that have been poured is counted n, until n ≥ n2, the steel liquid level in the tundish 3 is maintained and the time t is set. By controlling the opening V of the large ladle nozzle 2 z Make the weight of molten steel in the tundish 3 W z Maintain within a certain range, thereby maintaining the tundish 3 molten steel level; afterwards, as the pouring proceeds normally, until n≥n1 and the delay t2, the tundish 3 molten steel level maintaining working condition is exited and the timer t is reset to zero. The tundish 3 molten steel weight W z The process parameters are increased to normal production, and the casting machine returns to normal production. Here, n2 is the setting parameter for the number of active casting strands when tundish 3's molten steel level maintenance mode is activated; n1 is the setting parameter for the number of active casting strands when tundish 3's molten steel level maintenance mode is deactivated; and t2 is the setting parameter for the delay after reaching the set number of active casting strands under tundish 3's molten steel level maintenance mode. Therefore, parameters n1, n2, and t2 can be set according to different continuous casting machine models to match various types of casting strands, providing a wide range of applications.

[0021] Since there may be unexpected failures in pouring, in this case, manual operation can be switched to exit the automatic pouring state. However, in this case, not only the automation rate will be greatly reduced, but also the manual operation may not be timely. Therefore, in this embodiment: after entering the tundish 3 molten steel level maintenance working condition and timing t, when n < n1 and t > t1, the tundish 3 molten steel level maintenance working condition is exited and the timing t is reset to zero, and the tundish 3 molten steel weight W is z The parameters are increased to normal production process parameters, and the casting machine returns to normal production. Among them, t1 is the timeout setting parameter for the tundish 3 steel level maintenance condition. If an unexpected pouring failure occurs, even after a long time, the set number of cast streams n1 cannot be reached. In this case, the introduction of parameter t1 automatically exits the tundish 3 steel level maintenance condition if the operating time t in the tundish 3 steel level maintenance condition exceeds t1. This realizes automatic intervention in the event of a pouring failure, eliminating the need for operator intervention and improving the automation rate of the casting machine.

[0022] This method is suitable for a variety of casting machines such as slab casting machine, bloom casting machine, billet casting machine, etc. Among them, for billet casting machine with a large number of casting strands, the molten steel flow rate Q z Much larger than the molten steel flow Q flowing into the crystallizer 5 m By setting a larger n2, the opening V of the large ladle nozzle 2 can be reduced. z control difficulty.

[0023] This method has a wide range of applications and can be put into use by simply setting parameters according to different continuous casting machine models. For example, an 8-strand bloom casting machine automatically starts pouring 2 strands each time, which is completed in 4 times. Select t1=280 seconds, t2=70 seconds, n1=8, n2=2, and the weight of the tundish 3 molten steel required for automatic pouring is 20 tons. When the weight of the tundish 3 molten steel exceeds 20 tons, it triggers the automatic pouring state. When n≥2, it triggers the tundish 3 molten steel level maintenance state and counts t. By controlling the opening V of the ladle 2 z Make the weight of molten steel in the tundish 3 W z Maintain fluctuations around 20 tons to maintain the molten steel level in the tundish 3. When n≥8 and the delay is 70 seconds, the molten steel level holding condition of the tundish 3 is exited and the timer t is reset to zero. The weight of the molten steel in the tundish 3 is W. z Increase to normal production process parameters, the casting machine into normal production, if for some reason the casting machine does not start casting normally, always n < 8, then when t ≥ 280 seconds, exit the tundish 3 molten steel level holding condition and reset the timer t, tundish 3 molten steel weight W z Increase the process parameters to normal production and the casting machine returns to normal production.

[0024] Example 2

[0025] This embodiment provides a system for maintaining the liquid level of molten steel in the middle ladle during the automatic pouring process of a casting machine, including a large ladle water inlet opening adjustment mechanism, a medium ladle molten steel weight monitoring mechanism and a controller; the controller uses the method in Example 1 as the control strategy, and can control the large ladle water inlet opening adjustment mechanism to adjust the large ladle water inlet opening according to the medium ladle molten steel weight feedback from the medium ladle molten steel weight monitoring mechanism.

[0026] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A method for maintaining the molten steel level in the tundish during the automatic pouring process of a casting machine, characterized by: When the casting machine is in the automatic pouring state, the molten steel in the large ladle flows into the tundish through the large ladle water inlet, and the molten steel in the tundish flows into the crystallizer through the tundish water inlet. The opening of the large ladle water inlet is V z Influence of the molten steel flow rate Q flowing into the tundish z , Tundish water inlet opening V m Influence of molten steel flow rate Q flowing into the crystallizer m , the molten steel flow rate Q flowing into the tundish z The molten steel flow rate Q flowing into the crystallizer m Jointly determine the weight of molten steel in the tundish W z By controlling the opening of the ladle nozzle V z Make the weight of molten steel in the tundish W z Maintain within a certain range, thereby maintaining the molten steel level in the middle ladle; before the casting machine automatically starts pouring, the molten steel in the large ladle flows into the middle ladle through the large ladle water inlet, and the weight of the molten steel in the middle ladle is W z Gradually increase from zero until the weight of molten steel in the tundish is W z When the level increases to meet the automatic pouring requirement, the automatic pouring state is entered. The casting strand is gradually poured according to the process rules, and the number of cast strands that have been poured is counted n. When n≥n2, the tundish steel liquid level is maintained and the time t is set. By controlling the opening of the ladle nozzle V z Make the weight of molten steel in the tundish W z Maintain within a certain range, thereby maintaining the tundish molten steel level. Then, as the pouring proceeds normally, until n≥n1 and the delay is t2, the tundish molten steel level maintenance working condition is exited and the timer t is reset to zero. The tundish molten steel weight W z Increase to normal production process parameters, and the casting machine enters normal production; among them, n2 is the setting parameter for the number of opened casting streams when starting the tundish steel molten level maintenance condition, n1 is the setting parameter for the number of opened casting streams when stopping the tundish steel molten level maintenance condition, and t2 is the setting parameter for the delay time after reaching the set number of opened casting streams under the tundish steel molten level maintenance condition.

2. The method for maintaining the molten steel level in the tundish during the automatic pouring process of the casting machine according to claim 1, characterized in that: After entering the tundish steel liquid level maintenance working condition and timing t, when n<n1 and t>t1, the tundish steel liquid level maintenance working condition is exited and timing t is reset to zero. The weight of the tundish steel liquid is W z Increase to normal production process parameters, and the casting machine enters normal production; among them, t1 is the setting parameter of the timeout time under the condition of maintaining the tundish molten steel level.

3. The method for maintaining the molten steel level in the tundish during the automatic pouring process of the casting machine according to claim 1, characterized in that: For a billet casting machine with many strands, the molten steel flow rate Q z Much larger than the molten steel flow rate Q flowing into the crystallizer m By setting a larger n2, the opening of the water outlet of the large ladle can be reduced. z control difficulty.

4. The method for maintaining the molten steel level in the tundish during the automatic pouring process of a casting machine according to any one of claims 1 to 3, characterized in that: Casting machines include slab casting machines, bloom casting machines, and billet casting machines.

5. A system for maintaining the molten steel level in the tundish during the automatic pouring process of a casting machine, characterized by: The invention comprises a large ladle water inlet opening adjustment mechanism, a middle ladle molten steel weight monitoring mechanism and a controller; the controller adopts the method of maintaining the middle ladle molten steel level during the automatic pouring process of the casting machine as described in any one of claims 1 to 4 as a control strategy, and can control the large ladle water inlet opening adjustment mechanism to adjust the large ladle water inlet opening according to the middle ladle molten steel weight fed back by the middle ladle molten steel weight monitoring mechanism.

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