Method and system for keeping liquid level of tundish molten steel in automatic casting process of casting machine

Abstract

The invention discloses a method and system for keeping the liquid level of tundish molten steel in the automatic casting process of a casting machine, in the automatic casting state of the casting machine, the large ladle molten steel flows into a tundish through a large ladle nozzle, the tundish molten steel flows into a crystallizer through a tundish nozzle, and the opening degree Vz of the large ladle nozzle influences the flow Qz of the molten steel flowing into the tundish; the tundish nozzle opening Vm influences the flow Qm of the molten steel flowing into the crystallizer, the flow Qz of the molten steel flowing into the tundish and the flow Qm of the molten steel flowing into the crystallizer jointly determine the weight Wz of the molten steel in the tundish, the weight Wz of the molten steel in the tundish is kept within a certain range by controlling the large ladle nozzle opening Vz, and therefore the liquid level of the molten steel in the tundish is kept. According to the invention, the liquid level of the tundish molten steel is kept in a manner of controlling the opening degree of the ladle nozzle, and the consistency of each casting flow process parameter is ensured, so that the success rate of automatic casting of a casting machine is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of steelmaking continuous casting process in 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] In the metallurgical steelmaking and continuous casting industry, automatic pouring technology is widely demanded by steel mills, and almost every step of the technology involves controlling the flow rate of steel flowing into the crystallizer. The flow rate is generally controlled by the opening of the tundish water inlet. The larger the opening, the greater the flow rate, and vice versa. Moreover, the flow rate of steel flowing into the crystallizer is not only affected by the opening of the tundish water inlet, but also closely related to the liquid level of the molten steel in the tundish. When the opening value is constant, the higher the liquid level of the molten steel in the tundish, the greater the flow rate, and vice versa. It is generally impossible to directly obtain the height of the molten steel level in the tundish. Currently, it is mostly indirectly characterized by the weight of the molten steel in the tundish. The heavier it is, the higher the liquid level of the molten steel in the tundish, and vice versa.

[0003] Currently, most of 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 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 completed, thereby reducing the success rate of automatic pouring.

[0004] The number of strands contained in a casting machine varies depending on the type of continuous casting machine. At present, the automatic pouring technology solutions of most casting machines will not allow all strands to be poured at the same time, but will be poured gradually from front to back. In addition, the opening parameters in the automatic pouring steps rarely consider the change in the weight of the molten steel in the middle package. When the number of strands of the casting machine is small and the time interval between the front and back casting strands is short, the weight change of the middle package is relatively small, which barely meets the production needs. However, with the increasing number of strands of the current casting machine, it takes longer and longer to complete the pouring of all strands. As the pouring time increases, the actual liquid level of the molten steel in the middle package is also getting higher and higher. The actual deviation between the steel flow rate of the later casting strands and the set steel flow rate flowing into the crystallizer is too large, resulting in a significant decrease in 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 of a casting machine, and a system for maintaining the molten steel level in the middle ladle during the automatic pouring 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 each casting flow process parameter, thereby increasing the success rate of the automatic pouring of the casting machine.

[0006] The technical solution adopted by the present invention is: A method for maintaining the molten steel level in the middle ladle during the automatic pouring process of a casting machine. When the casting machine is automatically poured, 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 zInfluence of the molten steel flow rate Q into the tundish z , Tundish water inlet opening V m Influence of molten steel flow rate Q 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 water outlet V z The weight of molten steel in the tundish is W z Maintain it within a certain range to keep the molten steel level in the tundish.

[0007] 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 it increases to meet the automatic pouring condition, it enters the automatic pouring state, and 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 molten steel level in the middle ladle is maintained and the time t is set. By controlling the opening of the large ladle water outlet V z The weight of molten steel in the tundish is W z Maintain within a certain range, thereby maintaining the molten steel level in the middle ladle. Then, as the pouring proceeds normally, until n≥n1 and the delay is t2, the molten steel level in the middle ladle is exited and the timer t is reset to zero. The weight of the molten steel in the middle ladle is 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 for starting the steel molten level maintenance condition in the middle bag, n1 is the setting parameter for the number of opened casting streams for stopping the steel molten level maintenance condition in the middle bag, and t2 is the setting parameter for the delay time after reaching the set number of opened casting streams under the steel molten level maintenance condition in the middle bag.

[0008] Preferably, after entering the tundish steel molten level maintenance working condition and timing t, when n<n1 and t>t1, the tundish steel molten level maintenance working condition is exited and the timing t is reset to zero, and the tundish steel molten 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 molten steel level in the tundish.

[0009] Preferably, for a billet casting machine with a large number of casting 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 bag can be reduced. z control difficulty.

[0010] Preferably, the casting machine includes a slab casting machine, a bloom casting machine, and a billet casting machine.

[0011] A system for maintaining the molten steel level in a middle ladle during the automatic pouring process of a casting machine comprises a large ladle shroud opening adjustment mechanism, a medium ladle molten steel weight monitoring mechanism and a controller; the controller uses the above method for maintaining the molten steel level in the middle ladle during the automatic pouring process of the casting machine as a control strategy, and can control the large ladle shroud opening adjustment mechanism to adjust the large ladle shroud opening according to the medium ladle molten steel weight fed back by the medium ladle molten steel weight monitoring mechanism.

[0012] The beneficial effects of the present invention are: The invention controls the opening V of the ladle water outlet in the automatic pouring state. z The molten steel level in the tundish is maintained in this way, so that the same tundish water inlet opening V m The corresponding molten steel flow rate Q into the crystallizer m The 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 middle package W z The fluctuations are small within a certain range, which has a great impact on the flow rate Q of the molten steel flowing into the crystallizer. m The impact of can be ignored. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the steel flow path when the casting machine starts pouring.

[0014] In the figure: 1-big bag; 2-big bag water outlet; 3-medium bag; 4-medium bag water outlet; 5-crystallizer. DETAILED DESCRIPTION

[0015] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0016] Embodiment 1 This embodiment provides 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, Figure 1 As shown, the molten steel in ladle 1 flows into the middle ladle through the ladle inlet 2, and the molten steel in the middle ladle 3 flows into the crystallizer 5 through the middle ladle inlet 4. The opening of the ladle inlet 2 is V z Influence on the molten steel flow rate Q flowing into the tundish 3 z (V z Increase Q z Increase, and vice versa), the opening of the tundish water inlet 4 is V m Influence of the molten steel flow rate Q flowing into the crystallizer 5 m (V m Increase Q m 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 z Increase, and vice versa), by controlling the opening V of the large ladle water outlet 2 z The weight of molten steel in the middle package 3 is W z Maintain within a certain range, thereby maintaining the molten steel level in the middle ladle 3. This method controls the opening V of the large ladle nozzle 2 in the automatic pouring state. z The molten steel level in the tundish 3 is maintained in this way, so that the same tundish water inlet 4 opening V is maintained for both the early casting and the later casting. m The corresponding molten steel flow rate Q flowing into the crystallizer 5 m The convergence ensures the consistency of the process parameters of each casting strand, thereby increasing the success rate of automatic pouring of the casting machine; among them, the weight of molten steel in the middle package 3 W z The fluctuation is small within a certain range, which has an impact on the flow rate Q of the molten steel flowing into the crystallizer 5. m The impact of can be ignored.

[0017] The specific process of this method is: before the casting machine automatically starts 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 it increases to meet the automatic pouring condition, it enters the automatic pouring state; 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, it enters the tundish 3 steel liquid level maintenance condition and counts t, and controls the opening V of the ladle 2 by z The weight of molten steel in the middle package 3 is W z Maintain within a certain range, thereby maintaining the molten steel level in the tundish 3; afterwards, as the pouring proceeds normally, until n ≥ n1 and the delay is t2, the molten steel level maintenance 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, and the casting machine enters normal production. Among them: n2 is the setting parameter for the number of opened casting streams when starting the molten steel level maintenance condition of tundish 3, n1 is the setting parameter for the number of opened casting streams when stopping the molten steel level maintenance condition of tundish 3, and t2 is the setting parameter for the delay time after reaching the set number of opened casting streams under the molten steel level maintenance condition of tundish 3. Therefore, parameters n1, n2, and t2 can be set according to different continuous casting machine models to match various types of casting machines with different casting streams, and have a wide range of applications.

[0018] Since there may be unexpected pouring failures, in this case, the automatic pouring state can be switched to manual operation. 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 Increase to normal production process parameters, and the casting machine will enter normal production; among them, t1 is the setting parameter of the timeout time under the condition of molten steel level maintenance in tundish 3. When an unexpected failure to start pouring occurs, even after a long time, the set number of started casting streams n1 cannot be reached. At this time, the parameter t1 is introduced, and the molten steel level maintenance condition of tundish 3 can be automatically exited when the working time t of entering the molten steel level maintenance condition of tundish 3 exceeds t1, realizing automatic intervention in the case of failure to start pouring, without the need for operator intervention throughout the process, and improving the automation rate of the casting machine.

[0019] The method is suitable for a variety of casting machines such as slab casting machines, large square billet casting machines, and small square billet casting machines. Among them, for small square billet casting machines with a large number of casting strands, the molten steel flow rate Q flowing into the middle bag 3 is z Much larger than the molten steel flow rate Q flowing into the crystallizer 5 m By setting a larger n2, the opening V of the large ladle water inlet 2 can be reduced. z control difficulty.

[0020] The method has a wide range of applications and can be put into use by setting parameters according to different continuous casting machine models. For example, an 8-strand billet 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 molten steel in the middle bag 3 that meets the automatic pouring is 20 tons; when the weight of the molten steel in the middle bag 3 exceeds 20 tons, it triggers the automatic pouring state. When n≥2, it triggers the molten steel level maintenance working condition of the middle bag 3 and counts t. By controlling the opening V of the large ladle nozzle 2 z The weight of molten steel in the middle package 3 is W z Maintain fluctuations around 20 tons to maintain the molten steel level in the middle bag 3. When n ≥ 8 and the delay is 70 seconds, the molten steel level maintenance condition of the middle bag 3 is exited and the timer t is reset to zero. The weight of the molten steel in the middle bag W z Increase to normal production process parameters, the casting machine enters normal production. If for some reason the casting machine does not start casting normally, and n is always < 8, then when t ≥ 280 seconds, the molten steel level maintenance condition of the middle bag 3 is exited and the timer t is reset to zero. The weight of the molten steel in the middle bag 3 is W z Increase the process parameters to normal production and the casting machine will enter normal production.

[0021] Embodiment 2 The present 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, comprising 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 the first embodiment 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 weight of the middle ladle molten steel fed back by the medium ladle molten steel weight monitoring mechanism.

[0022] 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 the 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 creative work are within the scope of protection of the present application.

Claims

1. A method for maintaining the molten steel level in the tundish during the automatic pouring process of a casting machine, characterized in that: When the casting machine is in the automatic pouring state, the large ladle molten steel flows into the middle ladle through the large ladle water inlet, and the middle ladle molten steel flows into the crystallizer through the middle ladle water inlet. The large ladle water inlet opening V z Influence of the molten steel flow rate Q into the tundish z , Tundish water inlet opening V m Influence of the molten steel flow rate Q 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 water outlet V z The weight of molten steel in the tundish is W z Maintain it within a certain range to keep the molten steel level in the tundish.

2. The method for maintaining the molten steel level in the tundish during the automatic pouring process of the casting machine as claimed in claim 1, characterized in that: Before the casting machine starts pouring automatically, the molten steel in the large ladle flows into the middle ladle through the large ladle water inlet. 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 it increases to meet the automatic pouring condition, it enters the automatic pouring state, and 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 molten steel level in the middle ladle is maintained and the time t is set. By controlling the opening of the large ladle water outlet V z The weight of molten steel in the tundish is W z Maintain within a certain range, thereby maintaining the molten steel level in the middle ladle. Then, as the pouring proceeds normally, until n≥n1 and the delay is t2, the molten steel level in the middle ladle is exited and the timer t is reset to zero. The weight of the molten steel in the middle ladle is 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 for starting the steel molten level maintenance condition in the middle bag, n1 is the setting parameter for the number of opened casting streams for stopping the steel molten level maintenance condition in the middle bag, and t2 is the setting parameter for the delay time after reaching the set number of opened casting streams under the steel molten level maintenance condition in the middle bag.

3. The method for maintaining the molten steel level in the tundish during the automatic pouring process of the casting machine as claimed in claim 2, characterized in that: After entering the tundish steel level maintenance condition and timing t, when n<n1 and t>t1, the tundish steel level maintenance condition is exited and the timing t is reset to zero. The weight of the tundish steel 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 molten steel level in the tundish.

4. The method for maintaining the molten steel level in the tundish during the automatic pouring process of the casting machine as claimed in claim 2, characterized in that: For a billet casting machine with a large number of 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 bag can be reduced. z control difficulty.

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

6. A system for maintaining the molten steel level in the tundish during the automatic pouring process of a casting machine, characterized in that: 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 a method for maintaining the molten steel level of the middle ladle during the automatic pouring of a casting machine as described in any one of claims 1 to 5 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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