A method for changing a nozzle-equipped tundish in a continuous casting process

Abstract

The application provides a method for replacing a ladle with a submerged nozzle in a continuous casting process, and relates to the technical field of continuous casting processes, and comprises the following steps: providing at least two submerged nozzle ladles, at least some of the nozzles of the submerged nozzle ladles are provided with a pre-inclination angle; baking the submerged nozzle ladles, the inclination angle of the nozzles with the pre-inclination angle of the baked submerged nozzle ladles is smaller; using the baked submerged nozzle ladles to contain molten steel; removing the ladle at a pouring position; inserting the nozzles of the submerged nozzle ladles containing the molten steel into the multiple inlets of the crystallizers respectively; opening the submerged nozzle ladles and pouring; and solving the problem that the nozzles in the submerged nozzle ladles are difficult to be aligned with the inlets of the crystallizers in the replacement process of the submerged nozzle ladle.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of continuous casting process, and more particularly relates to a method for replacing tundish with a tundish with built-in nozzle in a continuous casting process. BACKGROUND

[0002] Efficient production of continuous casting is the trend of development of continuous casting process, and the tundish quick-change technology in the continuous casting process is a method for reducing the stop pouring of the casting machine and improving the operating efficiency of the casting machine. When the tundish with built-in nozzle is replaced, the nozzle extends downward in the tundish with built-in nozzle, and the tundish with built-in nozzle will deform during the roasting process, causing the nozzle to shift with the deformation of the tundish with built-in nozzle, and then it is difficult to center when the nozzle is inserted into the inlet of the crystallizer, which may cause the tundish replacement time to be too long, and if the centering is not accurate, the nozzle may be broken during the tundish replacement, affecting the production rhythm; at the same time, the long replacement time may cause the continuous casting billet to be cooled too much due to continuous spraying of cooling water, resulting in continuous casting billet stagnation. SUMMARY

[0003] The present application aims to solve the problem of difficulty in centering the nozzle of the tundish with built-in nozzle and the inlet of the crystallizer in the replacement process of the tundish with built-in nozzle in the prior art.

[0004] In order to achieve the above-mentioned purpose, the present application provides a method for replacing tundish with built-in nozzle in a continuous casting process, comprising:

[0005] providing at least two tundishes with built-in nozzles, at least part of the nozzles of the tundishes with built-in nozzles are provided with a pre-inclination angle;

[0006] roasting the tundishes with built-in nozzles, and the inclination angle of the nozzles with pre-inclination angle of the tundishes with built-in nozzles after roasting becomes smaller;

[0007] using the tundishes with built-in nozzles after roasting to hold molten steel;

[0008] removing the tundish at the pouring position;

[0009] inserting the nozzles of the tundishes with built-in nozzles holding molten steel into the inlets of the crystallizers, respectively;

[0010] opening the tundishes with built-in nozzles and pouring.

[0011] Optionally, a plurality of the nozzles are arranged below the tundish with built-in nozzles along the length direction of the tundish with built-in nozzles, and in a row of the nozzles, the lower ends of the nozzles close to the two ends are inclined inward, and the pre-inclination angle of the nozzles close to the two ends is greater than the pre-inclination angle of the nozzles close to the middle.

[0012] Optionally, in the row of the water gap, the pre-inclination angle of at least one of the water gap in the middle is zero degrees.

[0013] Optionally, the axes of the plurality of water gaps in the baked inner water gap tundish are parallel to each other.

[0014] Optionally, when the liquid level reaches the set liquid level during the process of the inner water gap tundish containing molten steel, the speed of the withdrawal straightening machine in the crystallizer is controlled to return to zero, and the secondary cooling gas and the secondary cooling water are turned off.

[0015] Optionally, it further comprises: setting the mounting gasket of the nozzle in the spraying structure in the secondary cooling zone of the crystallizer to be a heat-resistant gasket.

[0016] Optionally, before the plurality of water gaps of the inner water gap tundish containing molten steel are respectively inserted into the plurality of inlets of the crystallizer, it further comprises: inserting a connecting piece into the crystallizer and pulling the tail blank to a set position.

[0017] Optionally, the baking temperature of the inner water gap tundish is higher than 1100 degrees Celsius.

[0018] Optionally, the set liquid level is 260mm.

[0019] Optionally, the connecting piece is a steel cage, the speed of the tail blank is 1.2m / min-1.5m / min, and the set position is 200mm-300mm away from the lower mouth of the crystallizer.

[0020] The present application provides a kind of inner water gap tundish changing method in continuous casting process, its beneficial effect lies in: the inner water gap tundish changing method in continuous casting process at least part of the plurality of water gaps of inner water gap tundish is set to the state with pre-inclination angle, i.e. it is pre-set to be inclined, so that in the process of baking preheating inner water gap tundish, although the shell of inner water gap tundish will be deformed after heating, and then the lower end of water gap is displaced, but due to the setting of pre-inclination angle, the inclination angle of water gap with pre-inclination angle will be smaller in the process of baking, and then the difficulty of centering and inserting in the process of baking is reduced, so that the centering in the process of changing is easier, the changing efficiency is improved, the water gap is broken, and the time of water gap centering and inserting into crystallizer is reduced, the phenomenon of blanking caused by excessive cooling of casting blank can be avoided.

[0021] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0022] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0023] Figure 1 A flow chart of a method for replacing a tundish with an internal nozzle in a continuous casting process according to an embodiment of the present invention is shown.

[0024] Figure 2 A schematic diagram showing the initial state of a tundish with a built-in tundish nozzle in the prior art is shown.

[0025] Figure 3 The figure shows the state of the nozzle after the tundish with internal nozzle is baked in the prior art.

[0026] Figure 4 A schematic diagram of the nozzle state of a tundish with an internal nozzle in an initial state according to an embodiment of the present invention is shown.

[0027] Figure 5 A schematic diagram of the nozzle state after the internal nozzle tundish is baked according to an embodiment of the present invention is shown.

[0028] Description of reference numerals:

[0029] 1. Tundish with internal nozzle; 2. Nozzle. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Instead, these embodiments are provided to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0031] like Figure 1 As shown, the present invention provides a method for replacing a tundish with an internal nozzle in a continuous casting process, comprising:

[0032] At least two tundishes 1 with internal nozzles are provided, wherein at least some of the multiple nozzles 2 of the tundish 1 with internal nozzles are provided with a pre-tilt angle;

[0033] The inner nozzle tundish 1 is baked, and the inclination angle of the nozzle 2 with a pre-inclined angle of the inner nozzle tundish 1 becomes smaller after baking;

[0034] The baked inner nozzle tundish 1 is used to hold the molten steel;

[0035] Remove the tundish from the pouring position;

[0036] The multiple water nozzles 2 of the inner nozzle ladle 1 containing molten steel are respectively inserted into multiple inlets of the crystallizer;

[0037] The inner nozzle ladle 1 is opened, and pouring is performed.

[0038] Specifically, to solve the problem that the water nozzle 2 of the inner nozzle ladle 1 is difficult to be centered with the inlet of the crystallizer during the replacement of the inner nozzle ladle 1 in the prior art, the method for replacing the inner nozzle ladle 1 in the continuous casting process provided by the present application sets at least part of the multiple water nozzles 2 of the inner nozzle ladle 1 to have a pre-inclination angle, that is, the axis is pre-set to be inclined. In this way, during the baking and preheating of the inner nozzle ladle 1, although the shell of the inner nozzle ladle 1 will deform after being heated, and then the lower end of the water nozzle 2 will be displaced, due to the pre-inclination angle, the deformation and displacement during the baking process will make the inclination angle of the water nozzle 2 with the pre-inclination angle smaller, and then the difficulty of centering and inserting the water nozzle 2 into the inlet of the crystallizer during the deformation and displacement during the baking process is reduced, which makes the centering during the replacement process easier, improves the replacement efficiency, avoids the breakage of the water nozzle 2, and at the same time reduces the time for centering and inserting the water nozzle 2 into the crystallizer, which can avoid the phenomenon of excessive cooling of the cast slab.

[0039] Further, as shown in Figure 2 , the water nozzle 2 is a straight pipe connected below the inner nozzle ladle 1, and the inner nozzle ladle 1 is a steel ladle for containing molten steel; as shown in Figure 3 , the shell of the inner nozzle ladle 1 will deform during the baking and preheating process, and the general deformation form is that the two ends in the length direction are upwardly curved, so the multiple water nozzles 2 connected below the inner nozzle ladle 1 will be displaced, especially the displacement of the lower end of the water nozzle 2 is most obvious, and the displacement of the lower end of the water nozzle 2 will cause the water nozzle 2 to be difficult to be centered and inserted into the inlet of the crystallizer; in the method, as shown in Figure 4 , at least part of the water nozzles 2 are pre-set to have a pre-inclination angle, and based on the above analysis, the lower end of the water nozzle 2 close to the two ends is inwardly inclined, so that the inclination angle of the water nozzle 2 with the pre-inclination angle is smaller after deformation and displacement, and tends to be in the state of the water nozzle 2 as shown in Figure 5 .

[0040] Optionally, the multiple water nozzles 2 are arranged below the inner nozzle ladle 1 along the length direction of the inner nozzle ladle 1, and in a row of water nozzles 2, the lower end of the water nozzle 2 close to the two ends is inwardly inclined, and the pre-inclination angle of the water nozzle 2 close to the two ends is greater than the pre-inclination angle of the water nozzle 2 close to the middle.

[0041] In the embodiment, the eight water gaps 2 are arranged in a single row, the lower ends of the two outermost water gaps 2 are inwardly offset by 3-5 mm relative to the water gaps 2 in the initial state of extending vertically downward, thereby forming a pre-inclination angle, the lower ends of the two outer second water gaps 2 are inwardly offset by 2-3 mm, the two middle water gaps 2 extend vertically downward, and the two water gaps 2 adjacent to the two middle water gaps 2 are inwardly offset by 0-2 mm.

[0042] Optionally, in the row of water gaps 2, the pre-inclination angle of at least one water gap 2 in the middle is zero degrees.

[0043] Specifically, the water gap 2 in the middle receives little displacement of the lower end of the water gap 2 due to the deformation of the shell, and thus the pre-inclination angle thereof can be set to zero degrees.

[0044] Optionally, the axes of the plurality of water gaps 2 in the baked tundish 1 are parallel to each other.

[0045] Specifically, after the pre-inclination angles of the water gaps 2 are set according to the displacement of the lower end of the water gap 2 caused by the deformation of the shell of the tundish 1 during actual use, the axes of the water gaps 2 are parallel to each other in the optimal state after baking.

[0046] Optionally, when the liquid level reaches the set liquid level during the process of filling the tundish 1 with molten steel, the pulling speed of the withdrawal and straightening machine in the crystallizer is controlled to return to zero, and the secondary cooling gas and the secondary cooling water are turned off.

[0047] Specifically, when the tundish 1 is filled with the molten steel with the set displacement, the crystallizer starts to prepare for rapid tundish changing, at this time, the pulling speed of the withdrawal and straightening machine in the crystallizer is controlled to return to zero, and the secondary cooling gas and the secondary cooling water in the secondary cooling zone of the crystallizer are turned off to avoid excessive cooling of the billet.

[0048] Optionally, the installation gasket of the nozzle in the spraying structure in the secondary cooling zone of the crystallizer is a heat-resistant gasket.

[0049] Specifically, the nozzle in the spraying structure in the secondary cooling zone of the crystallizer sprays gas-water mixture to achieve cooling effect. In the prior art, the spraying structure continuously works and always sprays cooling gas-water mixture. The installation gasket of the nozzle is a rubber gasket, which plays a sealing role. However, in the method, to avoid excessive cooling of the billet and reduce the risk of billet stagnation, when the liquid level of the molten steel in the tundish 1 reaches the set liquid level, the spraying structure in the secondary cooling zone is turned off, at this time, the nozzle does not spray cooling gas-water mixture and will be subjected to high temperature. Therefore, the installation gasket of the nozzle is set to a heat-resistant gasket to avoid melting or deformation of the rubber gasket, loss of sealing effect, water leakage, and further avoidance of billet stagnation.

[0050] Optionally, before inserting the multiple water outlets 2 of the ladle with inner water outlet 1 containing molten steel into the multiple inlets of the crystallizer, the connecting piece is inserted into the crystallizer, and the tail blank is pulled to the set position.

[0051] Specifically, immediately after the ladle car of the casting position is driven away, the connecting piece is inserted, and the immersion depth of the connecting piece is more than 1 / 2 of the steel liquid, and the connecting piece is placed in the center of the cast blank as much as possible.

[0052] Optionally, the baking temperature of the inner water outlet ladle 1 is higher than 1100 degrees Celsius.

[0053] Specifically, the baking time of the standby inner water outlet ladle 1 is controlled to be 4h20min-4h45min, and the oxygen enrichment time is reasonably adjusted according to the calorific value of the gas to ensure that the baking temperature of the inner water outlet ladle 1 is higher than 1100 degrees Celsius.

[0054] Optionally, the liquid level is set to 260mm.

[0055] Specifically, when the liquid level of the molten steel in the standby inner water outlet ladle 1 reaches 260mm, the inner water outlet ladle of the casting position is lifted to the high position and quickly driven away.

[0056] Optionally, the connecting piece is a steel cage, the pulling speed of the tail blank is 1.2m / min-1.5m / min, and the set position is 200mm-300mm away from the lower mouth of the crystallizer.

[0057] In the embodiment, the standby inner water outlet ladle 1 and the inner water outlet ladle 1 of the casting position are both disposable ladles, which are the same ladle.

[0058] In summary, the inner water outlet ladle 1 changing method provided by the continuous casting process is used:

[0059] I. According to the specific situation of the inner water outlet ladle 1 in use, the spacing of the lower end of the water outlet 2 is optimized, that is, the pre-inclination angle is set. Figure 2 In order to optimize the shape of the water outlet 2 of the previous inner water outlet ladle 1, after baking, the inner water outlet ladle 1 is deformed, so that the water outlet 2 is inclined outward, and the state is as shown in Figure 3 The inclination angle of the water outlet 2 of the inner water outlet ladle 1 is adjusted, and the lower end of the two outermost water outlets 2 is offset inward by 3-5mm, and the remaining water outlets 2 are also optimized accordingly, and the state is as shown in Figure 4 After optimization, the inner water outlet ladle 1 is as shown in Figure 5 After baking, the water outlet 2 of the inner water outlet ladle 1 can reach the state of mutual parallelism, and then the centering and splicing operation with the inlet of the crystallizer can be quickly realized.

[0060] II. The standby built-in nozzle tundish 1 baking time is controlled in 4h20min~4h45min, the oxygen enrichment time is adjusted reasonably according to the calorific value of gas, and the built-in nozzle tundish 1 baking temperature is ensured to be higher than 1100 DEG C.

[0061] III. When the tundish liquid level of the casting position reaches 260mm, the speed of the straightening machine of the crystallizer is returned to zero, the secondary cooling gas and water of the secondary cooling zone of the crystallizer is closed, the built-in nozzle tundish 1 of the casting position is lifted to the high position, and then the tundish is quickly removed.

[0062] IV. The high-temperature resistant graphite gasket is used in the secondary cooling zone to avoid the melting of the rubber gasket after the secondary cooling water is closed, to avoid the water leakage and the billet stagnation;

[0063] V. After the tundish car of the built-in nozzle tundish 1 of the casting position is removed, the connecting piece is immediately inserted and immersed in the steel liquid with a depth of more than 1 / 2, the connecting piece is placed in the center of the cast slab as much as possible, and the tail billet is pulled to the position 200mm~300mm away from the lower mouth of the crystallizer at a speed of 1.2m / min-1.5m / min.

[0064] VI. The tundish car of the standby built-in nozzle tundish 1 is started to the casting position, is lowered to the upper part of the crystallizer inlet, is opened after the rough centering, then is lowered again to the built-in nozzle tundish 1, and then the water nozzle 2 is inserted into the inlet of the crystallizer, the ladle is opened, the full flow casting is carried out, the liquid level of the built-in nozzle tundish 1 is quickly lifted to the casting liquid level, and the casting page is about 600mm.

[0065] The above has described the embodiments of the present application, the above description is exemplary, is not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for replacing a tundish with an internal nozzle in a continuous casting process, characterized in that: include: Providing at least two tundishes with internal nozzles, wherein at least some of the multiple nozzles of the tundishes with internal nozzles are provided with a pre-tilt angle; Baking the tundish with an internal nozzle, wherein the inclination angle of the nozzle with a pre-inclination angle of the tundish with an internal nozzle becomes smaller after baking; The baked tundish with inner nozzle is used to hold molten steel; Remove the tundish from the pouring position; Inserting the multiple nozzles of the inner nozzle tundish containing molten steel into the multiple inlets of the crystallizer respectively; Open the tundish with inner nozzle to start pouring; The plurality of nozzles are arranged below the tundish with an internal nozzle along the length direction of the tundish with an internal nozzle. In a row of nozzles, the lower ends of the nozzles near the two ends are inclined inward, and the pre-inclination angles of the nozzles near the two ends are greater than the pre-inclination angles of the nozzles near the middle. In a row of nozzles, the pre-tilt angle of at least one nozzle in the middle is zero degree; After baking, the axes of the multiple nozzles of the internal nozzle tundish are parallel to each other; During the process of the inner-water-filled tundish containing molten steel, when the liquid level reaches the set level, the pulling speed of the straightening machine in the crystallizer is controlled to return to zero, and the secondary cooling air and the secondary cooling water are turned off; The baking temperature of the inner nozzle tundish is higher than 1100 degrees Celsius; Set the liquid level to 260mm.

2. The method for replacing a tundish with an internal nozzle in a continuous casting process according to claim 1, characterized in that: Also includes: The mounting gasket of the nozzle in the spray structure in the secondary cooling zone of the crystallizer is set to a heat-resistant gasket.

3. The method for replacing a tundish with an internal nozzle in a continuous casting process according to claim 1, characterized in that: Before the multiple nozzles of the inner nozzle tundish containing molten steel are respectively inserted into the multiple inlets of the crystallizer, the method further includes: inserting a connector into the crystallizer and pulling the tail billet to a set position.

4. The method for replacing a tundish with an internal nozzle in a continuous casting process according to claim 3, characterized in that: The connecting piece is a steel cage, the pulling speed of the tail billet is 1.2m / min-1.5m / min, and the set position is 200mm-300mm away from the lower mouth of the crystallizer.

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