Quick changing method for continuous casting tundish of ultra-width-to-thickness-ratio plate blank

Abstract

The invention relates to the technical field of ferrous metallurgy, in particular to an ultra-width-to-thickness-ratio slab continuous casting tundish quick-changing method, which comprises the following steps of: preparing a tundish required by next casting in advance, ensuring that the tundish and a submersed nozzle are fully baked to a specified temperature before being used, adjusting the pulling speed according to the amount of residual molten steel in the tundish, and when the liquid level of the molten steel in the tundish reaches the preset height, the stopper and the submersed nozzle are closed, the pulling speed is reduced, the tundish at the current pouring position is moved to the baking position, meanwhile, the standby tundish is moved to the pouring position, the position of the submersed nozzle of the standby tundish is adjusted, and it is ensured that a safe distance is kept between the standby tundish and a casting blank in the crystallizer. According to the method, the quick change time of the tundish is determined according to the production time, the tundish is prepared in advance and baked to the required temperature, quick change of the ultra-width-to-thickness-ratio slab continuous casting tundish is achieved, pulling speed adjustment is matched in the period, continuous production of continuous casting slabs is achieved, the shutdown frequency is reduced, and the productivity is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of iron and steel metallurgy, and particularly to a method for quickly replacing the tundish in continuous casting of ultra-wide and thick slab billets. Background Art

[0002] For an ultra-wide and thick slab continuous caster, the thickness of the mold is 150 mm, and the maximum width is 3300 mm. With a large width-to-thickness ratio, there are currently difficulties in quickly replacing the tundish, high requirements for time control, and the need to stop the machine at the end of each casting cycle, resulting in a large number of stoppages and limited production capacity improvement.

[0003] Based on this, the present application proposes a method for quickly replacing the tundish in continuous casting of ultra-wide and thick slab billets. Summary of the Invention

[0004] In view of the above technical problems, the present invention overcomes the shortcomings of the prior art and provides a method for quickly replacing the tundish in continuous casting of ultra-wide and thick slab billets. The method determines the tundish quick replacement time according to the production time, prepares the tundish in advance and bakes it to the required temperature, realizes the quick replacement of the tundish in continuous casting of ultra-wide and thick slab billets, adjusts the casting speed during the process, realizes the continuous production of continuous casting billets, reduces the number of stoppages, and greatly improves the production capacity.

[0005] The method for quickly replacing the tundish in continuous casting of ultra-wide and thick slab billets in this solution includes the following steps: Prepare the tundish required for the next casting cycle in advance, and ensure that the tundish and the submerged entry nozzle are fully baked to the specified temperature before use; Adjust the casting speed according to the remaining molten steel volume in the tundish, and check the status of the wall of the standby tundish, the stopper rod, and the submerged entry nozzle at a predetermined tonnage; Before the end of the current casting cycle, bring the first ladle of molten steel for the next casting cycle into place in advance and install the relevant equipment; Close the stopper rod and the submerged entry nozzle when the molten steel level in the tundish reaches the preset height, and reduce the casting speed; Move the tundish at the current casting position to the baking position, and at the same time move the standby tundish to the casting position; Adjust the position of the submerged entry nozzle of the standby tundish to ensure a safe distance from the cast billet in the mold; Measure the position of the cast billet in the mold to determine when to stop the casting speed; Connect the long nozzle and rotate the first furnace of molten steel for the next casting cycle to the casting position, and open the slide plate to let the molten steel flow out; Install the side slag stopper and the flow baffle; Start a new casting cycle under specific conditions, and gradually adjust the casting speed until the stable production speed is reached.

[0006] The further limited technical solution of the present invention is: Furthermore, the tundish baking temperature is at least 1100°C, and the submerged nozzle baking temperature is at least 800°C. The high-temperature preheating (1100°C and 800°C) of the tundish and the submerged nozzle can significantly reduce thermal shock and lower the risk of thermal fatigue of metallurgical equipment.

[0007] Furthermore, when the remaining molten steel in the tundish is 30 tons, 20 tons, 15 tons, and 10 tons respectively, the molten steel level is measured to determine the height of the molten steel level.

[0008] Furthermore, when the weight of the molten steel in the tundish drops to 25 tons, the states of the spare tundish wall, stopper rod, and submerged nozzle are checked. When it drops to 20 tons, the casting speed is reduced to 1.00 m / min. When it drops to 15 tons, the casting speed is further reduced to 0.80 m / min. The casting speed is gradually reduced (from 1.00 m / min to 0.80 m / min), reducing the difference in molten steel flow and improving the quality of casting forming.

[0009] Furthermore, when the height of the molten steel level in the tundish is about 200 mm, the stopper rod and the submerged nozzle are closed, and the casting speed is reduced to 0.1 m / min.

[0010] Furthermore, when the position of the slab in the mold is 450 mm from the upper opening, the casting speed is reduced to 0 m / min.

[0011] Furthermore, when the weight of the molten steel in the spare tundish is 8 tons, a new casting cycle is started, the stopper rod is opened to allow the molten steel to flow into the mold, and the time is recorded simultaneously. After 40 s, the casting speed is started to 0.1 m / min. When the slab travels 0.2 m, the casting speed is adjusted to 0.2 m / min. When the slab travels 0.4 m, the casting speed is adjusted to 0.3 m / min. When the slab travels 0.6 m, the casting speed is adjusted to 0.4 m / min. After the casting speed of 0.4 m / min pauses for 2 minutes, the casting speed is adjusted to 0.8 m / min. After the casting speed of 0.8 m / min pauses for 2 min, the casting speed slowly increases to 1.00 m / min. The pauses and slow adjustments at each casting speed stage are beneficial to stabilizing the slab forming process.

[0012] The beneficial effects of the present invention are as follows: (1) According to the production time, the present invention determines the tundish quick change time, prepares the tundish in advance and bakes it to the required temperature, realizes the quick change of the tundish for continuous casting of extra-wide and thick slab, and during which, in cooperation with the casting speed adjustment, realizes the continuous production of continuous casting billets, reduces the number of stops, and greatly improves the production capacity; (2) By preheating the tundish and the submerged nozzle at high temperature, the present invention can significantly reduce the thermal shock during the use of metallurgical equipment and lower the risk of thermal fatigue, thereby extending the service life of the equipment; (3) The gradual adjustment of the drawing speed and the precise control of the molten steel level height in the present invention help to reduce the difference in molten steel flow, make the casting more uniform, improve the quality of the final product. By measuring the position of the slab in the mold to determine when to stop the drawing speed and gradually adjusting the drawing speed when starting a new casting, the safety of the operation is ensured, and accidents that may be caused by too fast or inappropriate drawing speed changes are avoided. At the same time, the drawing speed is adjusted according to different stages of the remaining molten steel amount in the tundish, making reasonable use of each ton of molten steel, reducing energy consumption and material waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the mold in the specific embodiment of the present invention; Figure 2 It is a schematic diagram of the change in the drawing speed during the tundish quick change in continuous casting in the specific embodiment of the present invention. SPECIFIC EMBODIMENTS

[0014] This embodiment provides a method for quick changing the tundish in continuous casting of ultra-wide and thick ratio slab billets, where steel type A is butt-welded to steel type B, and the cross-sectional dimension is 3300*150mm. The structure of the mold used is as Figure 1 shown, and the change in the drawing speed during the tundish quick change is as Figure 2 shown.

[0015] The specific steps are as follows: 1. Prepare the tundish in advance according to the steel type B in the production plan of the next casting.

[0016] 2. Estimate the tundish quick change time and bake the tundish and the submerged entry nozzle 3 - 4 hours in advance.

[0017] 3. Contact the previous process in advance, and increase the molten steel temperature of the tundish before and after the quick change by 10 - 20°C on the original basis.

[0018] 4. Observe the baking situation of the spare tundish and the submerged entry nozzle. It is required that the baking temperature of the tundish is above 1100°C and the baking temperature of the nozzle is above 800°C (red-hot state).

[0019] 5. The first ladle of molten steel for the next casting arrives at the spare position 5 minutes in advance, and install the oil cylinder and wait.

[0020] 6. After the molten steel in the ladle of the last furnace of the previous casting is poured out, remove the mechanical sleeve and rotate the ladle turntable to the parallel position.

[0021] 7. Measure the molten steel level in the tundish at 30 tons, 20 tons, 15 tons, and 10 tons respectively according to the remaining molten steel tonnage in the tundish, and judge the height of the molten steel level in the tundish.

[0022] 8. When the tundish tonnage is 25 tons, check the condition of the spare tundish wall, stopper rod, and submerged entry nozzle. When the tundish tonnage is 20 tons, reduce the casting speed to 1.00 m / min, and when it is 15 tons, reduce the casting speed to 0.80 m / min.

[0023] 9. When the molten steel level in the tundish is about 200 mm, close the stopper rod and submerged entry nozzle, and reduce the casting speed to 0.1 m / min.

[0024] 10. Lift the tundish at the casting position and move it to the baking position, and at the same time, lift the spare tundish and move it to the casting position.

[0025] 11. After the spare tundish reaches the casting position, manually adjust the position of the submerged entry nozzle in the front, back, left, and right directions. After adjustment, lower the tundish height to ensure that the distance between the submerged entry nozzle and the slab in the mold is ≥ 10 cm.

[0026] 12. Measure the position of the slab in the mold. When the position is 450 mm from the upper mouth of the mold, reduce the casting speed to 0 m / min.

[0027] 13. Rotate the molten steel of the first furnace of the next casting heat to the casting position, connect the long nozzle, and open the slide plate to let the molten steel flow out.

[0028] 14. Install the side slag stopper and flow baffle.

[0029] 15. When the weight of steel grade B in the tundish is 8 tons, open the stopper rod to let the molten steel flow into the mold, and record the time at the same time. After 40 s, start the casting speed to 0.1 m / min. When the slab travels 0.2 m, adjust the casting speed to 0.2 m / min. When the slab travels 0.4 m, adjust the casting speed to 0.3 m / min. When the slab travels 0.6 m, adjust the casting speed to 0.4 m / min. After pausing for 2 minutes at a casting speed of 0.4 m / min, adjust the casting speed to 0.8 m / min. After pausing for 2 min at a casting speed of 0.8 m / min, slowly increase the casting speed to 1.00 m / min.

[0030] 16. Remove the pipeline of the offline tundish and prepare the next tundish according to the plan.

[0031] Except for the above embodiments, the present invention may have other embodiments. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A method for quick replacement of tundish in ultra-width-thickness ratio slab continuous casting, characterized in that: The following steps are involved: Prepare the tundish required for the next pouring in advance and ensure that the tundish and immersion nozzle are fully baked to the specified temperature before use; Adjust the casting speed according to the remaining molten steel in the tundish, and check the status of the spare tundish wall, stopper rod and submerged nozzle at the predetermined tonnage; Before the current pouring is finished, the first package of molten steel for the next pouring should be in place and the relevant equipment should be installed; When the molten steel level in the tundish reaches a preset height, close the stopper rod and the submerged nozzle, and reduce the casting speed; Move the tundish at the current pouring position to the baking position, and move the spare tundish to the pouring position; Adjust the position of the submerged nozzle of the spare tundish to ensure that it maintains a safe distance from the billet in the crystallizer; Measuring the position of the strand in the mold to determine when to stop the casting speed; Connect the long nozzle and rotate the first batch of molten steel for the next pouring to the pouring position, and open the slide plate to allow the molten steel to flow out; Install side slag deflectors and baffles; Start a new casting under specific conditions and gradually adjust the casting speed until a stable production speed is reached.

2. The method for quick replacement of tundish for continuous casting of ultra-width-thickness ratio slab according to claim 1, characterized in that: The baking temperature of the tundish is at least 1100°C, and the baking temperature of the submerged nozzle is at least 800°C.

3. The method for quick replacement of tundish for continuous casting of ultra-width-thickness ratio slab according to claim 1, characterized in that: When the remaining molten steel volume in the tundish is 30 tons, 20 tons, 15 tons and 10 tons respectively, the molten steel level is measured to determine the height of the molten steel level.

4. The method for quick replacement of tundish for continuous casting of ultra-width-thickness ratio slab according to claim 3, characterized in that: When the weight of molten steel in the tundish drops to 25 tons, check the status of the spare tundish wall, stopper rod and immersed nozzle. When it drops to 20 tons, reduce the pulling speed to 1.00m / min. When it drops to 15 tons, further reduce the pulling speed to 0.80m / min.

5. The method for quick replacement of tundish for continuous casting of ultra-width-thickness ratio slab according to claim 4, characterized in that: When the molten steel level in the tundish is about 200 mm, close the stopper rod and the immersed nozzle, and reduce the pulling speed to 0.1 m / min.

6. The method for quick replacement of tundish in ultra-width-thickness ratio slab continuous casting according to claim 1, characterized in that: When the position of the casting in the crystallizer is 450mm away from the upper opening, the pulling speed drops to 0m / min.

7. The method for quick replacement of tundish for continuous casting of ultra-width-thickness ratio slab according to claim 1, characterized in that: When the weight of the steel in the spare tundish is 8 tons, start a new pouring, open the stopper to allow the molten steel to flow into the crystallizer, and record the time. After 40 seconds, start the pulling speed to 0.1m / min, adjust the pulling speed to 0.2m / min when the billet travels 0.2m, adjust the pulling speed to 0.3m / min when the billet travels 0.4m, adjust the pulling speed to 0.4m / min when the billet travels 0.6m, pause at 0.4m / min for 2 minutes, then adjust the pulling speed to 0.8m / min, pause at 0.8m / min for 2min, then slowly increase the pulling speed to 1.00m / min.

Images