Continuous casting joint blank ejection method

Abstract

The invention discloses a continuous casting joint blank ejection method, and belongs to the technical field of continuous casting. By optimizing the opening degree of the adjusting valve, the cooling time and the secondary cooling water flow of the joint blank in the quick change process are reasonably controlled, the cooling strength of the joint blank is reduced, and damage of casting blank high temperature to a nozzle is reduced; the uniform straightening of the joint blank in the quick change process is ensured by adjusting the pressure distribution of the joint blank passing through the withdrawal and straightening machine; according to the actual ejection condition, the actual length of the joint blank is adjusted in real time, and it is ensured that the ejection process of the joint blank is stable and smooth; the length of the joint blank is optimized, the cutting loss of the joint blank is reduced, and the metal yield is increased. According to the method, the joint blank can be uniformly and slowly cooled, the straightening effect is improved, the influence of deformation such as bending, head warping and deviation of the joint blank in the quick change process on the blank ejection rhythm is effectively reduced, blank stagnation production accidents are reduced, and equipment loss and production cost are reduced; and meanwhile, online optimized fixed-length cutting of the joint blank is achieved, and the metal yield is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of continuous casting, more particularly to a continuous casting joint blank delivery method. BACKGROUND

[0002] As a common method to improve the continuous casting furnace number and reduce the group distance waiting time, the continuous casting tundish quick change is favored by more and more steel enterprises. The tundish quick change not only can improve the production efficiency and reduce the production cost, but also can reduce the workload of re-plugging the starter ingot and reduce the labor intensity of the operator.

[0003] In the tundish quick change process, the part connecting the tail of the cast blank poured by the former tundish and the head of the cast blank poured by the latter tundish is called joint blank. Efficient and stable quick change technology can make the joint blank more uniform, which is conducive to improving the product quality stability, and also conducive to smooth delivery process and reducing the occurrence of production accidents. However, in the actual production process, after the pouring of the former tundish is completed, the latter tundish needs to reach the pouring position, and after the tundish is opened, the new molten steel can enter the crystallizer and combine with the tail of the former tundish. At this time, the former tundish stays in the crystallizer for a long time, generally for 5-10 minutes. This will cause the tail of the former tundish to be overcooled, and the shell to be hardened, especially for steel with high carbon content, which will cause the head of the joint blank to be cooled strongly. In the case of insufficient straightening by the straightening and correcting machine, bending, head lifting, deviation and deformation may occur. When the deformed joint blank passes through the intermediate roller way and the delivery roller way, it may be lifted to the roller way or guide rail. If it is not found in time, serious production accidents such as blank stagnation and lifting to death may occur, which restricts the stable production of continuous casting.

[0004] Application No. CN120480131A discloses a method for quick change of tundish for slab continuous casting of high carbon steel. The method can eliminate the problem of tail blank falling off during normal stop pouring of slab continuous casting of high carbon steel, and solve the problem of joint blank steel or cast blank not moving during tundish quick change of slab continuous casting of high carbon steel by controlling the tonnage of new and old tundish at different stages and the corresponding casting speed adjustment range.

[0005] Application No. CN114734013A discloses a method for jointing of cast blank of continuous casting machine. At least one connecting piece is placed inside the crystallizer. Two-thirds of the connecting piece is adhered to the molten steel which has not yet solidified in the crystallizer, and one-third of the connecting piece is adhered to the tundish to be poured. The method reduces the influence of composition mixing of the joint blank, shortens the length of the joint blank, and improves the operation rate of the casting machine and the metal yield. The above two patent applications do not consider the delivery method under abnormal conditions such as bending, head lifting and deformation of the joint blank. SUMMARY

[0006] 1. Technical problems solved by the present application

[0007] In view of the defects and deficiencies of the prior art, the present application provides a continuous casting joint blank delivery method, which can uniformly and slowly cool the joint blank, improve the straightening effect, effectively reduce the influence of the deformation such as bending, head lifting and deviation of the joint blank in the quick change process on the delivery rhythm, reduce the blanking production accidents, and reduce the equipment loss and production cost; and simultaneously realize online optimization and cutting of the joint blank to improve the metal yield.

[0008] 2. Technical scheme

[0009] To achieve the above-mentioned purpose, the technical scheme provided by the present application is as follows:

[0010] The continuous casting joint blank delivery method of the present application has the following steps:

[0011] S1: when the tonnage of the tundish of the last furnace is 10-15 tons, start the tundish quick change program, preheat the standby tundish for 3.5-5 hours, the target temperature of the preheating is 1200-1350 DEG C, the target temperature of the nozzle preheating is 600-800 DEG C, and the tundish is opened to the waiting position for waiting;

[0012] S2: before the tundish of the last furnace stops casting, the slag in the crystallizer is reduced, and the inner and outer arc positions of the crystallizer are uniformly oiled; after the tundish car is driven away, the slag strip generated in the crystallizer is quickly processed, and the caked slag is fished out, and then the quick change connecting piece is installed;

[0013] S3: when the tail of the casting blank in the crystallizer is 400-600 mm away from the upper edge of the copper pipe of the crystallizer, the pulling speed is returned to 0 m / min, and the tundish car is lifted synchronously to prevent the waiting time from being too long to form a steel shell on the water nozzle and part of the blank tail, which affects the placement of the quick change connecting piece;

[0014] S4: after the pulling speed is returned to 0 m / min, the foot roller water is changed to intermittent water spraying: the opening degree of the adjusting valve of the foot roller water is adjusted to a, so that the nozzle has a certain amount of water to avoid being damaged by the high-temperature casting blank; at the same time, the opening time t1 and the closing time t2 of the adjusting valve are set, and t1-t2-t1 is a period;

[0015] S5: according to the carbon content of the produced steel, different parameters are set respectively;

[0016] S6: the flow of the two-cooling gas mist nozzle is adjusted to 10%-50% during production;

[0017] S7: open the standby tundish to the casting position, adjust the position of the submerged nozzle to ensure that the nozzle is centered with the crystallizer; open the ladle to pour when the ladle reaches 20-25 tons of molten steel, and then open the tundish to pour;

[0018] S8: The middle package quick change time is reduced to less than 8 minutes, i.e. the time interval from the stopping of pouring of the previous furnace middle package to the opening of pouring of the next furnace middle package is less than 8 minutes;

[0019] S9: The real-time position of the joint blank is monitored according to the ejection model;

[0020] S10: After the joint blank is completely ejected from the drawing and straightening machine, the actual length of each flow joint blank has been calculated by the secondary model, at this time, the length of the joint blank needs to be optimized according to the actual length Y of the tail blank of the previous furnace, the width L of the ejection cooling bed and the fixed size S of the production.

[0021] S11: In order to make the identification of the joint blank clear, special marks need to be made on the head and tail of each flow joint blank, which is convenient for production off-line checking.

[0022] Further, in the S5, when the carbon content of the produced steel grade is ≤0.45%, the opening degree a of the regulating valve of the foot roller water is in the range of 6%≤a≤10%, the opening state time t1 of the regulating valve is in the range of 10<t1≤15s, and the closing state time t2 of the regulating valve is in the range of 15<t2≤20s.

[0023] Further, in the S5, when the carbon content of the produced steel grade is >0.45%, the opening degree a of the regulating valve of the foot roller water is in the range of 2%≤a<6%, the opening state time t1 of the regulating valve is in the range of 0<t1≤10s, and the closing state time t2 of the regulating valve is in the range of 10<t2≤15s.

[0024] Further, in the S9, when the joint blank head distance from the V position of the arc-shaped section of the drawing and straightening machine V is set to 500-800mm, the pressure is increased to 2-3 times of the hot blank pressure, when the joint blank head distance from the V position of the horizontal section of the drawing and straightening machine V is set to 500-800mm, the pressure is increased to 1.5-2 times of the hot blank pressure, and the pressure increasing section lasts until the joint blank tail passes the corresponding Z position of the drawing and straightening machine Z, which is set to 1000-1500mm.

[0025] Further, in the S10, the allowable tolerance of S is ±d, due to the width limitation of the cooling bed, the length X of the joint blank needs to satisfy X≤L, which can be specifically divided into three cases.

[0026] Further, in the S10, the first case is: when the actual length of the tail blank of the previous furnace satisfies X+Y≤L, according to the ejection direction, the cutting is performed along the first end perpendicular to Y and the last end perpendicular to X, and the X+Y whole is treated as waste.

[0027] Further, in the S10, the second case is that when the actual length of the tail end of the previous furnace meets X+Y>L and Y

[0028] Further, in the S10, the third case is that when the actual length of the tail end of the previous furnace meets S-d≤Y≤S+d, according to the direction of the end of the blank, the end of the blank is cut along the end of the blank, the end of the blank is cut along the end of the blank, and the end of the blank is cut along the end of the blank.

[0029] According to the S10 method, the cutting loss of the joint blank can be reduced to the maximum extent to ensure smooth blanking, and the metal yield can be improved.

[0030] 3. Beneficial effects

[0031] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects:

[0032] The present application can make the joint blank cool uniformly and slowly, improve the straightening effect, effectively reduce the influence of the deformation of the joint blank, such as bending, head lifting and deviation, on the blanking rhythm during the quick change process, reduce the production accidents of the blanking, reduce the equipment loss and production cost, and realize the online optimization and cutting of the joint blank to the size, and improve the metal yield. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 The figure is a schematic diagram of the opening and closing time of the foot roller adjusting valve of the present application;

[0034] Fig. 2 The figure is a schematic diagram of the straightening pressure of the joint blank of the present application;

[0035] Fig. 3 The figure is a schematic diagram of the size optimization of the joint blank of the present application. DETAILED DESCRIPTION

[0036] The present application will be further described below in combination with the drawings and examples:

[0037] Example 1

[0038] From Figs. 1-3 It can be seen that the present example can.

[0039] Taking the production of a steel grade with a carbon content of 0.3% as an example, the size is 10.5m, the tolerance is ±0.1m, and the width of the cooling bed is 12m.

[0040] (1) When the ladle tonnage remaining in the previous furnace is 13 tons, start the ladle quick-change program, and preheat the standby ladle for 4.5 h, with the temperature of the ladle being heated to 1250°C and the temperature of the nozzle being heated to 750°C, and then open to the waiting position for waiting;

[0041] (2) Before the previous ladle stops casting, perform slag reduction in the mold, and uniformly apply oil to the inner and outer arc positions of the mold; after the ladle car is driven away, quickly process the slag strips generated in the mold, and remove the clumped slag, and then install the quick-change connecting piece;

[0042] (3) When the distance between the tail of the cast slab in the mold and the upper edge of the copper pipe of the mold is 420 mm at the time of stopping casting, the pulling speed is returned to 0 m / min, and the ladle car is simultaneously lifted, so as to prevent the waiting time from being too long, which causes the nozzle to drip steel and part of the tail of the slab to form a steel shell, thereby affecting the placement of the quick-change connecting piece;

[0043] (4) After the pulling speed is returned to 0 m / min, the foot roller water is changed to intermittent spraying: the opening degree of the adjusting valve of the foot roller water is adjusted to 7%, so that the nozzle has a certain amount of water to avoid being damaged by the high-temperature cast slab; the opening state time of the adjusting valve is 13 s, the closing state time of the adjusting valve is 20 s, and the cycle is repeated in turn;

[0044] (5) The flow of the secondary cooling gas mist nozzle is adjusted to 10% during production;

[0045] (6) Open the standby tundish to the casting position, and adjust the position of the submerged nozzle to ensure that the nozzle is centered with the mold; open the ladle to cast when the ladle is opened to cast, and open the stopper when the tonnage of the steel in the standby ladle reaches 25 t;

[0046] (7) The time interval between the stopping of the previous ladle and the opening of the next ladle is 7 min;

[0047] (8) According to the real-time position of the joint slab monitored by the out-of-mold model, when the head of the joint slab is 700 mm away from the arc-shaped section of the withdrawal machine, the pressure is increased to 2.5 times the hot slab pressure, when the head of the joint slab is 700 mm away from the horizontal section of the withdrawal machine V, the pressure is increased to 2 times the hot slab pressure, and the pressure increasing section lasts until the tail of the joint slab passes the corresponding withdrawal machine 1500 mm.

[0048] (9) After the joint slab completely exits the withdrawal machine, the actual length of each flow joint slab is 7 m, and the actual length of the tail slab of the previous furnace is 6 m, which satisfies X+Y>L and Y<S-d, at this time, the joint slab and the non-gauge of the previous furnace are cut and discarded, respectively, which can smoothly pass through the cooling bed and exit the mold.

[0049] (10) In order to make the identification of the joint slab clear, special marks need to be made at the head and tail of each flow joint slab, which is convenient for production off-line checking.

[0050] Example 2

[0051] From Figs. 1-3 It can be seen that:

[0052] Take the production of steel grade with carbon content of 0.6% as an example, the fixed size is 11m, the tolerance is ±0.08m, and the width of the cooling bed is 12m;

[0053] (1) When the ladle tonnage of the previous furnace is left with 15 tons, start the ladle quick change program, and the standby ladle is preheated for 5h, the heating temperature is 1300℃, the nozzle heating temperature is 780℃, and it is opened to the waiting position for waiting;

[0054] (2) Before the ladle of the previous furnace stops casting, the slag reduction operation is carried out in the crystallizer, and the inner and outer arc positions of the crystallizer are uniformly oiled; after the ladle car is driven away, the slag strip generated in the crystallizer is quickly treated, and the clumped slag is fished out, and then the quick change connecting piece is installed;

[0055] (3) When the crystallizer is stopped, the tail of the cast blank in the crystallizer is 500mm away from the upper edge of the copper pipe, the pulling speed is returned to 0m / min, and the ladle car is lifted synchronously to prevent the waiting time from being too long to form a steel shell on the water nozzle and part of the blank tail, affecting the placement of the quick change connecting piece;

[0056] (4) After the pulling speed is returned to 0m / min, the foot roller water is changed to intermittent water spray: adjust the opening degree of the foot roller water regulating valve to 5% to ensure that the nozzle has a certain amount of water to avoid being damaged by high-temperature cast blank; the opening state time of the regulating valve is 10s, and the closing state time of the regulating valve is 15s, and the cycle is repeated;

[0057] (5) The flow of the secondary cooling gas mist nozzle is adjusted to 10% during production;

[0058] (6) Open the standby tundish to the casting position, adjust the position of the submerged entry nozzle to ensure that the nozzle is centered with the crystallizer; open the ladle to cast when the ladle tonnage reaches 22t, and open the stopper when the ladle is cast;

[0059] (7) The time interval between the quick change of the previous furnace ladle and the opening of the next furnace ladle is 7.5min;

[0060] (8) According to the blank model monitoring, when the joint blank head is 800mm away from the arc section of the withdrawal machine, the pressure is increased to 3 times the hot blank pressure, when the joint blank head is 800mm away from the horizontal section of the withdrawal machine V, the pressure is increased to 2 times the hot blank pressure, and the pressure increasing section lasts until the joint blank tail passes the corresponding withdrawal machine 1500mm.

[0061] (9) After the joint blank completely exits the withdrawal machine, the actual length of each flow joint blank is 8m, and the actual length of the tail blank of the previous furnace is 10.95m, which meets the condition of S-d≤Y≤S+d, and is cut off according to the position shown in the figure. At this time, Y can be used as a positive blank, and only the 8m joint blank needs to be exchanged for waste treatment.

[0062] (10) In order to make the identification of the joint blank clear, special marks are needed on the head and tail of each flow joint blank, so as to facilitate production line checking.

[0063] The innovation of the present application is:

[0064] (1) By optimizing the opening degree of the regulating valve, the cooling time and the secondary cooling water flow of the joint blank during the quick change process are reasonably controlled, the cooling intensity of the joint blank is reduced, and the damage of the high temperature of the casting blank to the nozzle is reduced;

[0065] (2) By adjusting the pressure distribution of the joint blank through the straightening machine, the uniform straightening of the joint blank during the quick change process is ensured;

[0066] (3) According to the actual blanking condition, the actual length of the joint blank is adjusted in real time, so as to ensure the stable and smooth process of the joint blank during the blanking process;

[0067] (4) The length of the joint blank is optimized, the cutting loss of the joint blank is reduced, and the metal yield is improved.

[0068] The present application can make the joint blank uniform and slow cooling, improve the straightening effect, effectively reduce the influence of the deformation such as bending, head lifting and deviation of the joint blank during the quick change process on the blanking rhythm, reduce the production accidents of the blanking, reduce the equipment loss and production cost; at the same time, the online optimization cutting of the joint blank is realized, and the metal yield is improved.

[0069] The above describes the present application and its embodiments in a schematic manner, which is not limited, and the embodiments shown in the drawings are only one of the embodiments of the present application, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired thereby, without departing from the purpose of the present application, similar structural modes and embodiments can be designed without creativity, which should belong to the protection scope of the present application.

Claims

1. A method of casting a continuous-casting jointed bloom, characterized by: The steps are: S1: when the remaining tonnage of the last ladle is 10-15 tons, start the middle ladle quick change program, the standby middle ladle is pre-baked for 3.5-5 hours, the target temperature of baking is 1200-1350 DEG C, the water gap baking target temperature is 600-800 DEG C, and the waiting position is opened to wait; S2: before the last ladle stops casting, the slag reduction operation is carried out in the crystallizer, and the inner and outer arc positions of the crystallizer are uniformly oiled; after the middle ladle car leaves, the slag strip generated in the crystallizer is quickly processed, and the caked slag is fished out, and then the quick change connecting piece is installed; S3: when the distance between the tail of the casting blank in the crystallizer and the upper edge of the copper pipe of the crystallizer is 400-600 mm, the pulling speed is returned to 0 m / min, and the middle ladle car is lifted synchronously to prevent the water gap from dripping steel and part of the blank tail from forming a steel shell due to the long waiting time, which affects the placement of the quick change connecting piece; S4: after the pulling speed is returned to 0 m / min, the foot roller water is changed to intermittent spraying: the opening degree of the foot roller water regulating valve is adjusted to a, so that the nozzle has a certain amount of water to avoid being damaged by the high-temperature casting blank; at the same time, the opening time t1 and the closing time t2 of the regulating valve are set, and t1-t2-t1 is a cycle; S5: different parameters are set according to the carbon content of the produced steel grade; S6: the flow of the secondary cooling gas mist nozzle is adjusted to 10%-50% during production; S7: the standby middle ladle is opened to the casting position, the position of the submerged water gap is adjusted to ensure that the water gap is centered with the crystallizer; the ladle is opened, and when the tonnage of the steel in the standby middle ladle reaches 20-25 tons, the stopper is opened, and the middle ladle is opened; S8: the middle ladle quick change time is reduced to less than 8 min, that is, the time interval from the stop of the last ladle to the opening of the next ladle is less than 8 min; S9: the real-time position of the joint blank is monitored according to the blanking model; S10: after the joint blank is completely discharged from the straightening and leveling machine, the actual length of each flow joint blank has been calculated by the secondary model, at this time, the actual length of the last blank Y of the last furnace, the width L of the blank cooling bed and the production size S are needed to optimize the length of the joint blank; S11: in order to make the identification of the joint blank clear, special marks are made on the head and tail of each flow joint blank, which is convenient for production off-line checking.

2. A method of casting a continuous-casting jointed bloom according to claim 1, characterized in that: In the S5, when the carbon content of the produced steel grade is ≤0.45%, the opening degree a of the foot roller water regulating valve is in the range of 6%≤a≤10%, the opening time t1 of the regulating valve is in the range of 10 3. A method of casting a continuous-casting jointed bloom according to claim 1, characterized in that: In the S5, when the carbon content of the produced steel grade is >0.45%, the opening degree a of the foot roller water regulating valve is in the range of 2%≤a<6%, the opening time t1 of the regulating valve is in the range of 0 4. A method of casting a continuous-casting jointed bloom according to claim 1, characterized in that: The S9 is characterized in that when the joint blank head is away from the V position of the arc-shaped section of the straightening machine by 500-800 mm, the pressure is increased to 2-3 times of the hot blank pressure, when the joint blank head is away from the V position of the horizontal section of the straightening machine by 500-800 mm, the pressure is increased to 1.5-2 times of the hot blank pressure, and the pressure increasing section lasts until the joint blank tail passes the corresponding Z position of the straightening machine, and the Z position is set to 1000-1500 mm.

5. A method of casting a continuous-casting seam blank according to claim 1, characterized in that: In the S10, the allowable tolerance of S is ±d, and due to the width limitation of the cooling bed, the length X of the joint blank needs to satisfy X≤L, which can be specifically divided into three cases.

6. A method of casting a continuous-casting seam blank according to claim 5, characterized in that: In the S10, the first case is that when the actual length of the tail blank of the last furnace satisfies X+Y≤L, the blank is cut off along the first end perpendicular to Y and the last end perpendicular to X in the direction of the blank, and the X+Y is integrally treated as waste.

7. A method of casting a continuous cast jointed bloom according to claim 5, wherein: In the S10, the second case is that when the actual length of the tail blank of the last furnace satisfies X+Y>L and Y<S-d, the blank is cut off along the first end perpendicular to Y, the last end perpendicular to Y and the last end perpendicular to X in the direction of the blank, and the X and Y are treated as waste respectively.

8. A method of casting a continuous cast jointed bloom according to claim 5, wherein: In the S10, the third case is that when the actual length of the tail blank of the last furnace satisfies S-d≤Y≤S+d, the blank is cut off along the first end perpendicular to Y, the last end perpendicular to Y and the last end perpendicular to X in the direction of the blank, and the Y can be used as a normal blank, and only the X needs to be treated as waste. According to the method of S10, the cutting loss of the joint blank can be reduced and the metal yield can be improved under the premise of guaranteeing the smooth blanking.

Images