Bloom dummy ingot sealing and casting method

Abstract

The method comprises the steps that a dummy bar head on a dummy bar is fed into a proper position in a crystallizer, after a buffer is placed on a steel facing face of a dummy bar head dovetail groove, cold materials are laid on the bottom of the dummy bar head dovetail groove, the inclined face of the dovetail groove and the surface of the dummy bar head, and after dummy bar sealing is completed, the dummy bar head and the dummy bar head are sealed. And pouring tundish molten steel into the crystallizer, and when the liquid level of the molten steel reaches a specified height, pulling down the dummy bar to start throwing. By adopting the bloom dummy ingot sealing and casting method provided by the invention, the problems of bleed-out of the bloom dummy ingot, bleed-out in the casting process, dead flow and capping can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for sealing, starting and pouring a large square billet. Background Art

[0002] Sealing the ingot and starting the pouring are the key operation links of continuous casting production. It can be said that if the sealing and starting the pouring are done well, 90% of the work of the entire continuous casting is completed. Sealing the ingot is mainly to fill the gap between the ingot head and the wall of the crystallizer. Its purpose is to prevent the high-temperature molten steel from penetrating into the gap between the ingot head and the crystallizer when the continuous casting starts pouring, causing leakage during the pouring. The pouring is mainly the process of waiting for the stopper rod to drive the molten steel through the water inlet into the crystallizer with the sealed ingot, and gradually speeding up the casting machine to the production speed of the steel grade.

[0003] The existing sealing and pouring of ingots mainly have the following problems:

[0004] ① The existing method of sealing the ingot cannot effectively resist the impact of molten steel during the pouring process, which can easily cause the ingot to leak.

[0005] ② Improper control of the pouring process may cause steel leakage, dead flow or capping. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the prior art and provide a method for sealing and starting casting of a large square billet.

[0007] The present invention solves the technical problem by adopting the following technical solutions.

[0008] The invention provides a method for sealing and pouring a large square billet, which comprises: sending a dummy head on a dummy rod into a suitable position in a crystallizer, placing a buffer on the steel-facing surface of a dovetail groove of the dummy head, and then laying cold material on the bottom of the dovetail groove of the dummy head, the inclined surface of the dovetail groove and the surface of the dummy head; after sealing and pouring the dummy head, injecting molten steel from a tundish into the crystallizer, and pulling down the dummy rod when the level of the molten steel reaches a specified height to start drawing the billet.

[0009] The present invention has the following beneficial effects:

[0010] The present invention provides a method for sealing and starting a large square billet. The method for sealing and starting a large square billet provided by the present invention can effectively solve the problems of steel leakage during the starting of the large square billet, steel leakage during the starting process, dead flow and capping. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0012] Figure 1 This is a schematic diagram of using asbestos rope to seal between the starter head and the wall of the crystallizer during the process of sealing the starter of the large square billet;

[0013] Figure 2 It is a schematic diagram of the placement of the buffer on the ingot head during the process of sealing and ingoting of a large square billet;

[0014] Figure 3 It is a schematic diagram of the placement of iron nails and / or iron pins and steel plates in the dovetail groove of the ingot head during the process of sealing and drawing the large square billet;

[0015] Figure 4 This is a schematic diagram of the placement of steel plates and springs during the process of sealing and drawing the large square billet;

[0016] Figure 5 This is the casting speed control curve for the start of casting of large square billets. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0018] The following is a detailed description of a method for sealing and casting a large square billet provided by an embodiment of the present invention.

[0019] An embodiment of the present invention provides a method for sealing and casting a large square billet, which comprises: sending a dummy head on a dummy rod into a suitable position in a crystallizer, placing a buffer on the steel-facing surface of a dovetail groove of the dummy head, and then laying cold material on the bottom of the dovetail groove of the dummy head, the inclined surface of the dovetail groove and the surface of the dummy head; after sealing the dummy head, injecting molten steel from a tundish into the crystallizer, and when the level of the molten steel reaches a specified height, pulling down the dummy rod to start drawing the billet.

[0020] In some optional embodiments, sending the dummy head on the dummy rod to a suitable position in the crystallizer includes: after sending the dummy head to a position 450 mm from the upper opening of the crystallizer, blowing and cleaning it with compressed air, and sealing the gap between the dummy head and the four walls of the crystallizer with asbestos rope. Figure 1 shown.

[0021] In some optional embodiments, placing a buffer on the steel facing surface of the starter head dovetail groove includes: placing a buffer on the steel facing surface in the middle of the starter head dovetail groove, the buffer includes a support plate and a support foot, the support plate is placed on the starter head dovetail groove, a plurality of protrusions are arranged at intervals on the top of the support plate, one end of the support foot is fixedly connected to the support plate, and the length of the support foot is equal to the depth of the dovetail groove. Figure 2 The buffer can effectively improve the impact of molten steel on the ingot head, and at the same time can stabilize the flow of molten steel, allowing the molten steel to flow smoothly around to avoid the impact of molten steel on the surroundings.

[0022] In some optional embodiments, laying the cold material at the bottom of the dovetail groove of the starter head comprises the following steps:

[0023] Use iron nails and / or iron pins to cover the asbestos rope at the dovetail groove of the starter head, and at the same time, use the iron nails and / or iron pins to cover the opening of the dovetail groove of the starter head slightly inward;

[0024] Place a steel plate at the bottom of the dovetail groove of the ingot starter, close to the wide surface of the crystallizer, with the distance between the edge of the steel plate and the wide surface of the crystallizer being 10 mm. Figure 3 As shown;

[0025] Two steel plates are placed on the inclined surface in the middle of the dovetail groove of the starter head, and the bottoms of the two steel plates are against the edge of the steel plates at the bottom of the dovetail groove of the starter head;

[0026] Two rows of springs are placed horizontally at the bottom of the dovetail groove of the ingot head, with two springs in each row, totaling four springs.

[0027] In some optional embodiments, laying the cold material on the inclined surface of the dovetail groove of the starter head includes: placing a steel plate on each of the two inclined surfaces of the dovetail groove of the starter head, and then placing a cooling spring.

[0028] In some optional embodiments, laying the cold material on the surface of the starter head comprises the following steps:

[0029] Cover the asbestos rope on the top of the starter head with iron nails and / or iron pins, and evenly spread a layer of iron nails and / or iron pins on the top of the starter head except the buffer;

[0030] Place a steel plate on each side of the top of the ingot starter near the narrow surface of the crystallizer, with the distance between the edge of the steel plate and the narrow surface of the crystallizer being 10 mm;

[0031] Place 10 springs at the top of the ingot head except for the buffer, and the sealing of the ingot is completed. Figure 4 The cooling spring can further reduce the impact of molten steel on the iron pin and asbestos rope, ensure the stability of the sealed ingot, and accelerate the cooling and solidification of molten steel to ensure the thickness of the shell at the bottom of the ingot, further reducing the possibility of ingot leakage and starting leakage.

[0032] In some optional embodiments, the casting conditions include: when the molten steel in the tundish reaches 20 tons, the pouring operation is started, and the pouring tonnage cannot be advanced. If the molten steel in the tundish is poured in advance and the depth is not enough, it is easy to cause the tundish covering agent to be drawn into the crystallizer, resulting in "slag leakage" during the pouring process.

[0033] In some optional embodiments, the method further comprises: controlling the emergence time to be 30 to 45 seconds.

[0034] In addition to sealing and leading ingot continuous casting, the pouring process control also directly affects the success of pouring. Among them, the pouring emergence time (the time from molten steel flowing into the crystallizer to the starting of pulling speed) and the pulling speed increase control are the key to the control of the pouring process. If the pouring emergence time is short, the green billet shell is insufficient and the molten steel rushes out of the billet shell after starting, resulting in steel leakage; if the emergence time is too long, it is easy to cause the water inlet to freeze or cap (molten steel overflows from the crystallizer); improper control of the pouring start will cause steel leakage or pouring interruption.

[0035] According to the solution provided by the embodiment of the present invention, when the "start" button of the stopper mechanism is pressed, steel should flow out normally. If no steel flows out, the handle is turned upward to adjust the stopper opening. Each time the handle is turned, it is necessary to confirm whether the mechanism has moved. Repeat the action until the steel flows out normally. According to the emergence situation, the stopper control personnel can be instructed to operate the "close" or "open" crank of the stopper to adjust the size of the steel flow to ensure that the emergence time is 30 to 45 seconds. If the emergence time is insufficient for the billet shell, the molten steel will rush out of the billet shell after starting, resulting in steel leakage; if the emergence time is too long, it is easy to cause freezing of cold steel or capping of the water inlet (molten steel overflows from the crystallizer).

[0036] In some optional embodiments, the further comprising: adding pouring slag when the molten steel level is 250 mm away from the upper opening of the crystallizer, and the continuous casting machine automatically starting when the molten steel level is 200 mm away from the upper opening of the crystallizer.

[0037] In some optional embodiments, the method further comprises: 2 The acceleration is increased from 0m / min to 0.3m / min and then maintained for 15s, and then increased to 1.0m / min. 2 The acceleration is increased from 0.3m / min to 0.4m / min and then maintained for 12s, and finally to 1.0m / min. 2 The acceleration is increased from 0.4m / min to the normal production speed of 0.60m / min, and the entire pouring process is completed. Figure 5 shown.

[0038] The present invention will be further described below in conjunction with the embodiments.

[0039] Example 1

[0040] A method for sealing and starting a large square billet, the steps of which are as follows:

[0041] 1. Bloom sealing and ingot making

[0042] ① After the starter is sent to a position 450mm from the top of the crystallizer, it is cleaned with compressed air, and the gap between the starter and the crystallizer wall is tied with asbestos rope. The asbestos rope should be tied flat and solid. Figure 1 shown.

[0043] ② Place the buffer in the ingot head and make sure it is placed firmly and correctly. Figure 2 The buffer comprises a support plate and a support foot, the support plate is placed on the dovetail groove of the ingot starter head, a plurality of protrusions are arranged at intervals on the top of the support plate, one end of the support foot is fixedly connected to the support plate, and the length of the support foot is equal to the depth of the dovetail groove.

[0044] ③ Use iron nails and / or iron pins to cover the asbestos rope at the dovetail groove of the starter head. At the same time, the iron nails and / or iron pins should cover the opening of the dovetail groove of the starter head slightly inward, but not too far inward. Figure 3 shown.

[0045] ④ Place a steel plate at the bottom of the dovetail groove of the ingot starter, close to the wide surface of the crystallizer, i.e. the dovetail groove bottom steel plate. The distance between the edge of the steel plate and the wide surface of the crystallizer is 10mm. Figure 3 shown.

[0046] ⑤ Place two steel plates, namely the middle steel plates of the dovetail groove, on the inclined surface in the middle of the dovetail groove of the ingot guide head. The bottom of the middle steel plate of the dovetail groove is against the edge of the steel plate at the bottom of the dovetail groove. At the same time, two springs are placed between the middle steel plate of the dovetail groove and the wall of the crystallizer, and two rows of springs are placed horizontally at the bottom of the dovetail groove, two springs in each row, totaling four springs.

[0047] ⑥ Place a steel plate on each of the two inclined surfaces of the dovetail groove of the ingot head, that is, the steel plates on both sides of the dovetail groove, and then place a cooling spring on each of the steel plates on both sides of the dovetail groove.

[0048] ⑦ Cover the asbestos rope on the top of the ingot starter head with iron nails and / or iron pins, and evenly sprinkle a layer of iron nails and / or iron pins on other positions on the top of the ingot starter head except the buffer.

[0049] ⑧ Place a steel plate on each side of the top of the starter head close to the narrow surface of the crystallizer, namely the steel plates on both sides of the starter head. The distance between the edges of the steel plates on both sides of the starter head and the narrow surface of the crystallizer is 10mm.

[0050] ⑨ Place 10 springs at other positions on the top of the ingot head except the buffer, and the ingot is tied here. Figure 4 shown.

[0051] 2. Bloom pouring

[0052] ① When the molten steel in the tundish reaches 20t, pouring operation is carried out, and the pouring tonnage cannot be advanced.

[0053] ② When the "start" button of the stopper mechanism is pressed, steel flow should flow out normally. If there is no steel flow, turn the handle upward to adjust the stopper opening. Once the handle is turned, it is necessary to confirm whether the mechanism is moving. Repeat the action until the steel flow flows out normally. According to the emergence situation, the stopper control personnel can be instructed to operate the stopper "close" or "open" crank to adjust the steel flow size to ensure that the emergence time is 30 to 45 seconds.

[0054] ③ When the molten steel level is 250mm away from the upper mouth of the crystallizer, add the pouring slag. When the molten steel level is 200mm away from the upper mouth of the crystallizer, the continuous casting machine automatically starts. Figure 5 As shown, the starting speed is 1.5m / min 2 The acceleration is increased from 0m / min to 0.3m / min and then maintained for 15s, and then increased to 1.0m / min. 2 The acceleration is increased from 0.3m / min to 0.4m / min and then maintained for 12s, and finally to 1.0m / min. 2 The acceleration is increased from 0.4m / min to the normal production speed of 0.60m / min. The entire pouring process is now completed.

[0055] After adopting this solution, the sealing effect of the ingot was greatly improved, and the problem of ingot leakage during pouring was basically solved. The pouring process was controlled stably, and the number of pouring failures per month was ≤1.

[0056] Comparative Example 1

[0057] Sealing the ingot means sending the ingot head to a fixed position inside the crystallizer, blowing off the water and debris on the ingot head and the crystallizer wall, and then manually filling the gap between the ingot head and the crystallizer wall with dry paper rope or asbestos rope, and keeping the asbestos rope flush with the ingot head, and spreading a layer of dry iron filings around the crystallizer wall to press the asbestos rope; finally, putting the cold steel bar into the crystallizer, covering the surface of the ingot head and spreading iron filings. The result is: when pouring, the iron filings may be flushed away under the impact of the steel flow, and the weak parts of the sealing material paper rope or asbestos rope will burn after encountering molten steel, causing molten steel to penetrate into the gap between the ingot head and the crystallizer, resulting in ingot leakage, and a high failure rate of pouring, with leakage and pouring failure 5 times per month. Seriously affecting production.

[0058] Comparative Example 2

[0059] The steps are similar to those in Example 1, except that no buffer is installed during the process of sealing the ingot. The results are as follows: due to the absence of a buffer, the steel flow has a huge impact on the ingot head during the pouring process, causing the ingot head to be easily burned and cracked. At the same time, the steel flows horizontally and rapidly around, and the impact of the molten steel on the surroundings is as large as before. Although there is a cooling spring buffering effect, which can improve the burning of the sealing material, the pouring failure rate is still high, with leakage and pouring failure 4 times per month.

[0060] Comparative Example 3

[0061] The steps are similar to those in Example 1, except that no cooling spring is installed during the process of sealing the ingot. The cooling spring can reduce the impact of molten steel on the iron pin and asbestos rope, ensure the stability of the sealed ingot, and accelerate the cooling and solidification of the molten steel to ensure the thickness of the shell at the bottom of the ingot, further reducing the possibility of ingot leakage and steel leakage at the start. The result is that due to the buffer, the impact of molten steel on the surroundings during the pouring process is significantly improved compared with the original, but the surroundings have the same impact resistance to molten steel, and the pouring failure rate is still high, with leakage and pouring failure 3 times per month.

[0062] Comparative Example 4

[0063] The steps are similar to those in Example 1, except that when the molten steel in the tundish reaches 10 tons, the pouring operation is performed. When the tundish tonnage is low, the tundish covering agent is drawn into the molten steel, and the molten steel mixed with the covering agent flows into the crystallizer, and the cast billet leaks after it leaves the crystallizer. As a result, the pouring operation leaks and fails 3 times per month.

[0064] Comparative Example 5

[0065] The steps are similar to those in Example 1, except that the pouring slag is added when the molten steel level is 350 mm from the upper mouth of the crystallizer. If the pouring slag is added too early, the molten steel in the crystallizer has not yet covered the outlet hole, and the molten steel impacting the pouring slag easily causes the molten steel to roll slag, and the casting billet leaks after leaving the crystallizer. As a result, the pouring leaks and the pouring fails 2 times per month.

[0066] Comparative Example 6

[0067] The steps are similar to those in Example 1, except that: 2 The acceleration was increased from 0m / min to 0.5m / min. The starting speed was too fast, and the billet shell was thin and insufficient in strength when it came out of the crystallizer, which easily led to steel leakage and failure of pouring. Leakage and failure of pouring occurred 2 times a month.

[0068] By analyzing the results of the embodiments of the present invention and the comparative examples, it can be seen that: the use of a buffer in the process of sealing the ingot can effectively improve the impact of molten steel on the ingot head, and at the same time can play a role in stabilizing the flow of molten steel, allowing the molten steel to flow smoothly to the surroundings to avoid the impact of molten steel on the surroundings; the use of a cooling spring can further reduce the impact of molten steel on the iron pin and asbestos rope, ensuring the stability of the sealed ingot, and at the same time can accelerate the cooling and solidification of the molten steel to ensure the thickness of the shell at the bottom of the ingot, further reducing the possibility of ingot leakage and starting leakage; optimizing the control of the pouring process, specifically controlling the pouring tonnage of the tundish, the timing of adding the pouring slag, and the starting pulling speed can effectively solve the problems of large square billet ingot leakage, steel leakage during the pouring process, dead flow, and capping.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for sealing and casting a large square billet, characterized in that: include: Send the dummy head on the dummy rod into the appropriate position in the crystallizer, place a buffer on the steel-facing surface of the dovetail groove of the dummy head, and then lay cold material on the bottom of the dovetail groove of the dummy head, the inclined surface of the dovetail groove and the surface of the dummy head. After the dummy is sealed, inject the molten steel from the tundish into the crystallizer. When the liquid steel level reaches the specified height, pull down the dummy rod to start drawing.

2. The method according to claim 1, characterized in that Sending the dummy head on the dummy rod to the appropriate position in the crystallizer includes: after the dummy head is sent to a position 450mm away from the upper opening of the crystallizer, it is cleaned with compressed air, and the gap between the dummy head and the four walls of the crystallizer is sealed with asbestos rope.

3. The method according to claim 1, characterized in that Placing a buffer on the steel facing surface of the dovetail groove of the ingot starter head includes: placing a buffer on the steel facing surface in the middle of the dovetail groove of the ingot starter head, the buffer includes a support plate and a support foot, the support plate is placed on the dovetail groove of the ingot starter head, a plurality of protrusions are arranged at intervals on the top of the support plate, one end of the support foot is fixedly connected to the support plate, and the length of the support foot is equal to the depth of the dovetail groove.

4. The method according to claim 1, characterized in that: Laying cold material at the bottom of the dovetail groove of the starter head includes the following steps: Use iron nails and / or iron pins to cover the asbestos rope at the dovetail groove of the starter head, and at the same time, use the iron nails and / or iron pins to cover the opening of the dovetail groove of the starter head slightly inward; Place a steel plate at the bottom of the dovetail groove of the ingot starter, close to the wide surface of the crystallizer, with the distance between the edge of the steel plate and the wide surface of the crystallizer being 10 mm; Two steel plates are placed on the inclined surface in the middle of the dovetail groove of the starter head, and the bottoms of the two steel plates are against the edge of the steel plates at the bottom of the dovetail groove of the starter head; Two rows of springs are placed horizontally at the bottom of the dovetail groove of the ingot head, with two springs in each row, totaling four springs.

5. The method according to claim 1, characterized in that The method of laying cold material on the inclined surface of the dovetail groove of the ingot starter head comprises: placing a steel plate on each of the two inclined surfaces of the dovetail groove of the ingot starter head, and then placing a cooling spring.

6. The method according to claim 1, characterized in that Laying cold material on the surface of the starter head includes the following steps: Cover the asbestos rope on the top of the starter head with iron nails and / or iron pins, and evenly spread a layer of iron nails and / or iron pins on the top of the starter head except the buffer; Place a steel plate on each side of the top of the ingot starter near the narrow surface of the crystallizer, with the distance between the edge of the steel plate and the narrow surface of the crystallizer being 10 mm; Place 10 springs at the top of the ingot starter head except for the buffer, and the sealing of the ingot starter is completed.

7. The method according to claim 1, characterized in that The casting conditions include: when the molten steel in the tundish reaches 20t, the pouring operation is carried out, and the pouring tonnage cannot be advanced.

8. The method according to claim 1, characterized in that: Also includes: Control the germination time to 30 to 45 seconds.

9. The method according to claim 1, characterized in that: Also includes: When the molten steel level is 250mm away from the upper mouth of the crystallizer, add the pouring slag. When the molten steel level is 200mm away from the upper mouth of the crystallizer, the continuous casting machine starts automatically.

10. The method according to claim 1, characterized in that Also includes: At 1.5m / min 2 The acceleration is increased from 0m / min to 0.3m / min and then maintained for 15s, and then increased to 1.0m / min. 2 The acceleration is increased from 0.3m / min to 0.4m / min and then maintained for 12s, and finally to 1.0m / min. 2 The acceleration is increased from 0.4m / min to the normal production pulling speed of 0.60m / min, and the entire pouring process is completed.

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