Argon replacement device and method for circular-truncated-cone-shaped tundish

Abstract

The invention relates to an argon replacement device and method for a circular-truncated-cone-shaped tundish, belongs to the technical field of die casting, and solves the problems that in the prior art, a circular-truncated-cone-shaped tundish argon blowing replacement pipe cannot go deep into the lower portion of the tundish, gas circulation in the circulating tundish is poor, and the argon replacement efficiency is low. An argon replacement device for a circular-truncated-cone-shaped tundish comprises a long pipe replacement device and a short pipe replacement device. The long pipe replacement device comprises a first air inlet hose, a long straight bent pipe, a 90-degree bent pipe and a 270-degree bent pipe which are connected in sequence; the first air inlet hose is connected with an inlet of the horizontal part of the long straight bent pipe through a horizontal joint, an outlet of the vertical end of the long straight bent pipe is connected with the vertical end of the 90-degree bent pipe through a vertical joint, and the horizontal end of the 90-degree bent pipe is connected with the 270-degree bent pipe through a horizontal joint; the short pipe replacement device comprises a second air inlet hose and a short straight bent pipe which are connected through a horizontal connector. And thorough, stable and efficient air replacement of the circular-truncated-cone-shaped tundish is achieved.

Description

Technical Field

[0001] The invention relates to the field of die casting technology, and in particular to a device and method for replacing argon in a truncated cone-shaped tundish. Background Art

[0002] In the die-cast steelmaking production process, argon replacement is an indispensable step in the production of high-purity steel ingots to prevent the refined molten steel from being contaminated by secondary oxidation. Argon replacement is usually carried out during pouring and covering the tundish. However, due to the unreasonable layout of the argon blowing protection device, the molten steel is easily exposed to direct air and oxidized, resulting in secondary pollution that affects the quality of the steel ingots.

[0003] At present, the mold casting workshop uses a self-made argon blowing replacement device, which starts blowing argon after the tundish is arranged. The argon blowing pipe cannot be extended too long, otherwise it will affect the distribution and circulation of argon in the tundish and the pipeline stability will be poor, which leads to poor air replacement effect at the bottom of the tundish. Summary of the invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide an argon replacement device and method for a truncated cone-shaped tundish, so as to solve at least one of the problems of poor gas circulation in the tundish during the existing air replacement process of the truncated cone-shaped tundish, poor air replacement effect and low replacement efficiency at the bottom of the tundish, the inability of the existing argon blowing device for the tundish to simultaneously achieve efficient air replacement and protective casting, and poor device stability after the existing argon blowing device for the tundish is extended too long.

[0005] On the one hand, an embodiment of the present invention provides a truncated cone tundish argon replacement device, including a long tube replacement device and a short tube replacement device;

[0006] The long tube replacement device comprises a first air intake hose, a long straight elbow, a 90° elbow and a 270° elbow connected in sequence; the long straight elbow comprises a long straight elbow horizontal portion and a long straight elbow vertical portion;

[0007] The first air intake hose is connected to the inlet of the horizontal part of the long straight elbow through a horizontal joint, the outlet of the vertical end of the long straight elbow is connected to the vertical end of the 90° elbow through a vertical joint, and the horizontal end of the 90° elbow is connected to the 270° elbow through a horizontal joint;

[0008] The short pipe replacement device comprises a second air intake hose and a short straight elbow pipe connected by a horizontal joint, and the short straight elbow pipe comprises a short straight elbow horizontal portion and a short straight elbow vertical portion.

[0009] It should be noted that before pouring, the long tube replacement device and the short tube replacement device work simultaneously, and argon is introduced into the tundish; during the pouring process, the short tube replacement device works alone, and argon is introduced into the tundish.

[0010] Specifically, the calculated inner diameters of the first air intake hose, the second air intake hose, the long straight elbow, the short straight elbow, the 90° elbow, and the 270° elbow are a,

[0011]

[0012] a- calculated value of the inner diameter of the pipe, in mm;

[0013] Q- is the argon gas flow rate, in m 3 / h;

[0014] V- is the argon gas flow rate, in m / h;

[0015] The actual inner diameters of the first air intake hose, the second air intake hose, the long straight elbow, the short straight elbow, the 90° elbow, and the 270° elbow are a±1mm; the inner diameters of the horizontal joint and the vertical joint are both a+4mm.

[0016] Furthermore, the length of the vertical portion of the long straight elbow is H-(200-300) mm, wherein H is the height of the truncated cone-shaped tundish.

[0017] Specifically, in the long tube replacement device, the central plane where the 90° elbow is located is perpendicular to the central plane where the 270° elbow is located.

[0018] Furthermore, the length of the vertical portion of the short straight elbow in the short pipe replacement device is 200mm-300mm, and the inner diameter of the 270° elbow is 200mm-300mm.

[0019] Preferably, the horizontal joint and the vertical joint are made of stainless steel pipes, and the wall thickness of the stainless steel pipes is 5-8 mm.

[0020] On the other hand, an embodiment of the present invention further provides a method for replacing argon in a truncated cone-shaped tundish, comprising the following steps:

[0021] S1. Assemble the replacement device and connect the gas source: before pouring, assemble the long tube replacement device and the short tube replacement device respectively according to the connection order and position relationship; place the assembled replacement device at the designated position of the tundish, wherein the first air inlet hose and the second air inlet hose are located outside the tundish and connected to the external gas source;

[0022] S2. Argon replacement before pouring: Open the external gas source connected to the first gas inlet hose and the second gas inlet hose, and introduce argon into the tundish. At the same time, use the long tube replacement device and the short tube replacement device to replace the argon in the tundish before receiving the refined molten steel. When the refining sliding nozzle is opened, close the external gas source connected to the long tube replacement device. The ventilation time before pouring is 15-20 minutes. After the ventilation is completed, quickly pull the long tube replacement device out of the tundish;

[0023] S3. Argon replacement during pouring: During the pouring process, keep the external gas source connected to the first gas inlet hose closed and the external gas source connected to the second gas inlet hose open, and use a short tube replacement device alone to perform gas replacement. When the pouring is completed, turn off the gas source.

[0024] It should be noted that the long tube replacement device is placed in an area with a radius of 85mm-100mm around the truncated cone-shaped middle core rod; the short tube replacement device is placed at a distance of ≤400mm from the edge of the cover hole.

[0025] Preferably, the pressure of the argon outlet in the argon replacement device is 0.2-0.4Mpa.

[0026] Preferably, the flow rate of argon in the argon replacement device is 22.6-45.2m 3 / h.

[0027] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0028] 1. The present invention arranges reasonable argon replacement for the truncated cone-shaped tundish before and during pouring, including a long tube replacement device and a short tube replacement device, wherein the length of the vertical portion of the long straight curved tube extends into the bottom of the tundish, so that the air in the tundish is more thoroughly removed, thereby ensuring the replacement effect of the gas at the bottom of the tundish; the length of the short straight curved tube in the short tube replacement device is controlled to be 200mm-300mm, thereby ensuring that the outlet of the short tube replacement device can penetrate into the tundish cover and does not touch the molten steel surface during pouring.

[0029] 2. The present invention improves the lower outlet form of the long tube replacement device, adopts a 270° elbow outlet, and maintains a 90° layout between the plane where the outlet is located and the plane where the long straight elbow is located, thereby realizing the transformation of the gas circulation of the tundish from the original single up and down circulation to the up and down plus all-around surrounding circulation, so that the gas streamline has a certain tangential or surrounding speed, which better promotes the gas flow at the bottom of the tundish and improves the circulation effect; the tangential speed of the airflow effectively reduces the vibration caused by the gas flow, avoids the movement or shaking of the long tube replacement device caused by uneven airflow or direct impact of the airflow on the bottom of the tundish, and improves the stability of the system. Therefore, a larger argon flow rate can be used, which significantly improves the replacement efficiency and improves the applicability of the replacement device of the present invention to large-size tundishes.

[0030] 3. The present invention designs the bending radius of the 270° elbow to be 200-300 mm. On the one hand, it ensures that the starting area of ​​the gas rotation flow at the bottom of the tundish is large enough to fully drive the air at the bottom of the tundish upward, so that the oxygen mass fraction in the tundish before pouring is lower than 9.7%; on the other hand, it achieves a balance between the airflow stability, uniformity and airflow intensity at the outlet of the 270° elbow.

[0031] 4. The present invention reasonably designs the argon replacement procedure. Before pouring, the long tube replacement device and the short tube replacement device are used simultaneously to ensure that the air in the tundish is completely removed and the replacement efficiency is further improved. During pouring, the long tube replacement device is withdrawn and the short tube replacement device is used alone to continuously introduce argon into the clear area of ​​the molten steel in the tundish, so that the molten steel is never in contact with the air during the pouring process, thereby realizing protective pouring during the mold casting process and preventing secondary oxidation.

[0032] 5. The present invention optimizes the layout of the long tube replacement device and the short tube replacement device, and utilizes the fact that the tundish core rod is usually arranged in an easily accessible position, so that the long tube replacement device is placed in an area within a range of 85mm-100mm of the center radius of the truncated cone tundish core rod, so that the operator can quickly withdraw the long tube replacement device from the tundish when starting to pour, so that the operator does not need additional equipment or enter a hard-to-reach area when performing the operation;

[0033] The short tube replacement device is placed at a distance ≤400mm from the edge of the ladle cover hole to achieve argon sealing of the tundish throughout the entire pouring process.

[0034] 6. The replacement device and replacement method provided by the present invention are simple to implement, the argon blowing process is uniform and stable, and the operation is convenient. The increase in hydrogen content of the ingot after pouring is controlled to be ≤0.00008%, the increase in oxygen content is ≤0.004%, the increase in nitrogen content is ≤0.0025%, and the Al content burn-in value is ≤0.008%.

[0035] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0037] Figure 1 It is a schematic diagram of the long tube replacement device of the present invention;

[0038] Figure 2 It is a schematic diagram of the short tube replacement device of the present invention;

[0039] Figure 3 It is a schematic diagram of the argon replacement method of the truncated cone tundish of the present invention;

[0040] FIG4( a ) is a perspective view of the assembly of the truncated cone tundish argon replacement device of the present invention;

[0041] FIG4( b ) is a perspective view of the assembly of the truncated cone-shaped tundish argon replacement device of the present invention;

[0042] FIG. 4( c ) is a top view of the assembly of the argon replacement device of the frustum-shaped tundish of the present invention.

[0043] Reference numerals:

[0044] 1-first air intake hose; 2-horizontal joint; 3-long straight elbow; 4-vertical joint; 5-90° elbow; 6-270° elbow; 7-second air intake hose; 8-short straight elbow; 9-edge of the cover hole; 10-area around the truncated cone-shaped middle core rod. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0046] On the one hand, a specific embodiment of the present invention discloses a truncated cone-shaped tundish argon replacement device, including a long tube replacement device and a short tube replacement device, such as Figure 1 , Figure 2 As shown;

[0047] The long tube replacement device comprises a first air intake hose 1, a long straight elbow 3, a 90° elbow 5 and a 270° elbow 6 connected in sequence; the long straight elbow 3 comprises a long straight elbow horizontal portion and a long straight elbow vertical portion;

[0048] The first air intake hose is connected to the horizontal inlet of the long straight elbow 3 through a horizontal joint 2, the vertical outlet of the long straight elbow 3 is connected to the vertical end of the 90° elbow 5 through a vertical joint 4, and the horizontal end of the 90° elbow 5 is connected to the 270° elbow 6 through a horizontal joint 2;

[0049] The short pipe replacement device comprises a second air intake hose 7 and a short straight elbow 8 connected via a horizontal joint 2, wherein the short straight elbow comprises a short straight elbow horizontal portion and a short straight elbow vertical portion.

[0050] It should be noted that before pouring, the long tube replacement device and the short tube replacement device work simultaneously, and argon is introduced into the tundish; during the pouring process, the short tube replacement device works alone, and argon is introduced into the tundish.

[0051] Compared with the prior art, the argon replacement device for the truncated cone tundish of the present invention comprises a long tube replacement device and a short tube replacement device. By making reasonable argon replacement arrangements before and during the pouring of the truncated cone tundish, in which the length of the vertical part of the long straight curved tube extends into the bottom of the tundish, the air in the tundish can be more thoroughly removed, thereby ensuring the replacement effect of the gas at the bottom of the tundish.

[0052] When in use, the long tube replacement device is placed in the area 10 around the truncated cone tundish core rod, and the area is an area within a radius of 85mm-100mm with the truncated cone tundish core rod as the center. The short tube replacement device is placed near the edge 9 of the cover hole to achieve argon sealing of the tundish during the entire pouring process; before pouring, the long tube replacement device and the short tube replacement device are used at the same time to ensure that the air in the tundish is completely removed and the replacement efficiency is further improved; during pouring, the long tube replacement device is withdrawn and the short tube replacement device is used alone to continuously introduce argon into the clear area of ​​the molten steel in the tundish, so that the molten steel is always not in contact with the air during the pouring process, thereby protecting the casting process and preventing secondary oxidation.

[0053] Specifically, the calculated value of the inner diameter of the first air intake hose, the second air intake hose, the long straight elbow, the short straight elbow, the 90° elbow, and the 270° elbow is a, in mm. Q is the argon gas flow rate, in m 3 / h, V is the argon gas flow rate, in m / h; the actual inner diameters of the first air inlet hose, the second air inlet hose, the long straight elbow, the short straight elbow, the 90° elbow, and the 270° elbow are a±1mm; the actual inner diameters of the horizontal joint and the vertical joint are both a+4mm;

[0054] Preferably, the air intake hose is made of rubber, and the air intake hose is connected to the horizontal joint by insertion, wherein the horizontal joint is inserted into the air intake hose; the connection methods between the horizontal joint and the long straight elbow, the long straight elbow and the vertical joint, and the vertical joint and the 270° elbow are all sleeve-type connections, and a fixing knob is provided at the joint to ensure that the pipes are firmly connected to each other.

[0055] Furthermore, the length of the vertical portion of the long straight curved pipe is L, L = H-(200-300) mm, wherein H is the height of the truncated cone-shaped tundish, and the units of L and H are both mm; the length of the vertical portion of the long straight curved pipe extends into the bottom of the tundish, so that the argon gas can directly reach the bottom of the tundish, and the air in the tundish is more thoroughly removed, thereby better ensuring the replacement effect of the gas at the bottom of the tundish.

[0056] The design of the 270° elbow in the long tube replacement device allows the gas flow to have a certain tangential or circumferential speed, which can better promote the gas flow at the bottom of the tundish. Compared with the long straight elbow that directly penetrates into the bottom of the tundish, it avoids the problem of gas rushing directly to the bottom of the tundish after leaving the outlet, poor gas circulation, and incomplete replacement.

[0057] The tangential velocity of the airflow effectively reduces the vibration caused by the gas flow, avoids the movement or shaking of the long tube replacement device caused by uneven airflow or direct impact of the airflow on the bottom of the ladle, and improves the stability of the system. Therefore, a larger argon flow rate can be used, which significantly improves the replacement efficiency and improves the applicability of the replacement device of the present invention to large-sized ladle.

[0058] Specifically, the angle between the central plane where the 90° elbow and the central plane where the 270° elbow are located in the long tube replacement device is 90°; the bending radius of the 270° elbow is 200-300 mm to ensure that the starting area of ​​the gas rotation flow at the bottom of the tundish is large enough; and to achieve a balance between the stability, uniformity and airflow intensity of the 270° elbow outlet air flow; if the bending radius of the 270° elbow is too large, the tangential velocity of the outlet gas will be too small and the rotational flow at the outlet will be too weak, which is not conducive to driving the air at the bottom of the tundish upward; if the bending radius of the 270° elbow is too small, the tangential velocity of the outlet gas will be too large, which is not conducive to reducing the vibration caused by the gas flow and affecting the stability of the long tube replacement device.

[0059] Specifically, the vertical portion of the short straight bend in the short tube replacement device is 200mm-300mm long, and the thickness of the tundish cover is 180mm-200mm. Therefore, the length setting of the short straight bend ensures that the outlet of the short tube replacement device can penetrate into the tundish cover without contacting the molten steel surface during pouring.

[0060] Furthermore, the bottom end of the vertical part of the short straight curved tube in the short tube replacement device does not contact the molten steel surface in the tundish, but is located above it; if it contacts the molten steel surface during the pouring process, on the one hand, the air above the molten steel in the tundish cannot be continuously replaced, which may cause the molten steel to contact with the air, and on the other hand, it may cause the molten steel to splash, increasing the risk of large inclusions in the steel.

[0061] Preferably, the horizontal joint and the vertical joint are made of stainless steel pipes with a wall thickness of 5-8 mm; the long straight bend pipe, the short straight bend pipe, the 90° bend pipe and the 270° bend pipe are made of stainless steel with a wall thickness of 5-8 mm.

[0062] In a possible design, the short straight bend vertical portion of the short tube replacement device and the long straight bend vertical portion of the long straight bend can both be designed as retractable structures to meet the needs of tundishes of different specifications.

[0063] On the other hand, a specific embodiment of the present invention further discloses a method for replacing argon in a truncated cone-shaped tundish, comprising the following steps:

[0064] S1. Assemble the replacement device and connect the gas source: before pouring, assemble the long tube replacement device and the short tube replacement device respectively according to the connection order and position relationship; place the assembled replacement device at the designated position of the tundish, wherein the first air inlet hose and the second air inlet hose are located outside the tundish and connected to the external gas source;

[0065] S2. Argon replacement before pouring: Open the external gas source connected to the first gas inlet hose and the second gas inlet hose, and introduce argon into the tundish. At the same time, use the long tube replacement device and the short tube replacement device to replace the argon in the tundish before receiving the refined molten steel. When the refining sliding nozzle is opened, close the external gas source connected to the long tube replacement device, and quickly withdraw the long tube replacement device from the tundish. The ventilation time before pouring is 15-20 minutes;

[0066] S3. Argon replacement during pouring: During the pouring process, keep the external gas source connected to the first gas inlet hose closed and the external gas source connected to the second gas inlet hose open, and use a short tube replacement device alone to perform gas replacement. When the pouring is completed, turn off the gas source.

[0067] It should be noted that the designated position described in step S1 is the area where the long tube replacement device is placed within the range of 85mm-100mm of the center radius of the truncated cone-shaped tundish core rod; the short tube replacement device is placed at a distance of ≤400mm from the edge of the tundish cover hole. The short tube replacement device enters the tundish through the small hole on the edge of the tundish cover, and at the same time facilitates the long tube replacement device to be withdrawn from the tundish before pouring. The positions of the two cannot be changed.

[0068] It should be noted that, in step S2, argon replacement before pouring is performed by blowing argon with a long tube replacement device, the flow form of the gas flow tends to be a circulating flow, and the circulating flow basically occupies more than 1 / 2 of the space of the ladle, the maximum gas flow rate can reach 2m / s, and the long tube device with a 270° elbow can fully drive the air at the bottom of the ladle upward; at the same time, a short tube replacement device is used to blow argon to improve the replacement efficiency;

[0069] When the refining sliding nozzle is opened, the liquid steel level in the ladle will gradually rise to a higher height, and the long tube device cannot be used. After the external air source connected to the long tube replacement device is turned off, the long tube replacement device must be quickly pulled out of the ladle to avoid affecting the pouring process.

[0070] Preferably, the pressure of the argon outlet in the argon replacement device in steps S2 and S3 is 0.2-0.4Mpa, such as 0.2Mpa, 0.25Mpa, 0.3Mpa, 0.35Mpa, 0.4Mpa; the flow rate of argon is 22.6-45.2m 3 / h, such as 22.6m 3 / h、28.25m 3 / h、30m 3 / h、33.9m 3 / h、40m 3 / h、45.2m 3 / h;

[0071] During the pouring process, it is not appropriate for the argon blowing flow rate and pressure to be too large or too small. After the argon gas enters the tundish through the short argon blowing tube, it escapes from the core rod outlet. At the position of the middle pouring port, if the argon blowing flow rate is too large, air will be sucked in, causing the oxygen content in the ingot to increase; if the argon blowing pressure is too high, the gas flow rate will be fast, which will disturb the poured steel flow and affect the replacement effect of the tundish.

[0072] In summary, the present invention implements a long and short combined argon blowing device, wherein the length of the vertical part of the long straight elbow extends into the bottom of the tundish, so that the air in the tundish is more thoroughly removed, thereby ensuring the replacement effect of the gas at the bottom of the tundish; by improving the lower outlet form of the long tube replacement device and adopting a 270° elbow outlet, the gas flow has a certain tangential or circumferential speed, which better promotes the gas flow at the bottom of the tundish and improves the circulation effect; the tangential speed of the gas flow effectively reduces the vibration caused by the gas flow and improves the stability of the system; by designing a reasonable bending radius of the 270° elbow, it is ensured that the starting area of ​​the gas rotation flow at the bottom of the tundish is large enough to fully drive the air at the bottom of the tundish upward.

[0073] The argon replacement device and method for the frustum-shaped tundish of the present invention will be described below with reference to specific embodiments.

[0074] Example 1

[0075] This embodiment provides Figure 1 , 2 , and 3 show an argon replacement device and method suitable for a truncated cone-shaped intermediate package.

[0076] The assembly relationship of the truncated cone tundish argon replacement device in this embodiment is as follows: Figure 4(a) , 4(b) , as shown in 4(c);

[0077] In this embodiment, the truncated cone-shaped tundish can accommodate 60 tons of molten steel.

[0078] The replacement device consists of the following:

[0079] The long tube replacement device includes: a first air intake hose, a long straight elbow, a 90° elbow, a 270° elbow, a horizontal joint, and a vertical joint;

[0080] The short pipe replacement device comprises: a second air intake hose, a short straight elbow pipe, and a horizontal joint.

[0081] The dimensions of the components of the long tube replacement device and the short tube replacement device are as follows:

[0082] The inner diameters of the first air intake hose 1 and the second air intake hose 7, the long straight elbow 3, the short straight elbow 8, the 90° elbow 5, and the 270° elbow 6 in the long tube replacement device and the short tube replacement device are 20 mm, and the bending radius is 200 mm; the inner diameters of the horizontal joint 2 and the vertical joint 4 are both 24 mm;

[0083] The vertical length of the long straight curved pipe in the long pipe replacement device is H-200mm, where H is the height of the truncated cone-shaped tundish; the vertical length of the long straight curved pipe in the short pipe replacement device is 200mm;

[0084] The horizontal joint 2 and the vertical joint 4 are made of 5 mm thick stainless steel pipes.

[0085] The replacement method is:

[0086] S1. Assemble the replacement device and connect the gas source: before pouring, assemble the long tube replacement device and the short tube replacement device respectively according to the connection order and position relationship; place the assembled replacement device at the designated position of the tundish, wherein the first air inlet hose and the second air inlet hose are located outside the tundish and connected to the external gas source;

[0087] S2. Argon replacement before pouring: Open the external gas source connected to the first gas inlet hose and the second gas inlet hose, and introduce argon into the tundish. At the same time, use the long tube replacement device and the short tube replacement device to replace the argon in the tundish before receiving the refined molten steel. When the refining sliding nozzle is opened, close the external gas source connected to the long tube replacement device, and quickly withdraw the long tube replacement device from the tundish. The ventilation time before pouring is 15 minutes;

[0088] S3. Argon replacement during pouring: During the pouring process, keep the external gas source connected to the first air inlet hose closed and the external gas source connected to the second air inlet hose open, and use a short tube replacement device alone to perform gas replacement. When the pouring is completed, turn off the gas source. The argon gas flow time during the pouring process is 32 minutes.

[0089] The pressure of the argon outlet in the argon replacement device is 0.2Mpa, and the argon flow rate is 22.6m 3 / h.

[0090] The oxygen mass fraction in the ladle before pouring was measured using the Optima7 handheld flue gas analyzer, as shown in Table 1. The ingots after pouring were sampled and tested to examine the changes in gas content and Al content. The results are shown in Table 2.

[0091] Example 2

[0092] This embodiment provides an argon replacement device and a replacement method suitable for a truncated cone-shaped tundish.

[0093] In this embodiment, the truncated cone-shaped tundish can accommodate 60 tons of molten steel.

[0094] The replacement device consists of the following:

[0095] The long tube replacement device includes: a first air intake hose, a long straight elbow, a 90° elbow, a 270° elbow, a horizontal joint, and a vertical joint;

[0096] The short pipe replacement device comprises: a second air intake hose, a short straight elbow pipe, and a horizontal joint.

[0097] The dimensions of the components of the long tube replacement device and the short tube replacement device are as follows:

[0098] The inner diameters of the first air intake hose 1 and the second air intake hose 7, the long straight elbow 3, the short straight elbow 8, the 90° elbow 5, and the 270° elbow 6 in the long tube replacement device and the short tube replacement device are 21 mm, and the bending radius is 200 mm; the inner diameters of the horizontal joint 2 and the vertical joint 4 are both 25 mm;

[0099] The vertical length of the long straight curved pipe in the long pipe replacement device is H-50mm, where H is the height of the truncated cone-shaped tundish; the vertical length of the long straight curved pipe in the short pipe replacement device is 250mm;

[0100] The horizontal joint 2 and the vertical joint 4 are made of 6.5 mm thick stainless steel pipes.

[0101] The replacement method is:

[0102] S1. Assemble the replacement device and connect the gas source: before pouring, assemble the long tube replacement device and the short tube replacement device respectively according to the connection order and position relationship; place the assembled replacement device at the designated position of the tundish, wherein the first air inlet hose and the second air inlet hose are located outside the tundish and connected to the external gas source;

[0103] S2. Argon replacement before pouring: open the external gas source connected to the first gas inlet hose and the second gas inlet hose, and introduce argon into the tundish. At the same time, use the long tube replacement device and the short tube replacement device to replace the argon in the tundish before receiving the refined molten steel. When the refining sliding nozzle is opened, close the external gas source connected to the long tube replacement device, and quickly withdraw the long tube replacement device from the tundish. The ventilation time before pouring is 17.5 minutes;

[0104] S3. Argon replacement during pouring: During the pouring process, keep the external gas source connected to the first air inlet hose closed and the external gas source connected to the second air inlet hose open, and use a short tube replacement device alone to perform gas replacement. When the pouring is completed, turn off the gas source. The argon gas flow time during the pouring process is 31.5 minutes.

[0105] The pressure of the argon outlet in the argon replacement device is 0.3Mpa; the flow rate of the argon replacement device is 33.9m 3 / h.

[0106] The oxygen mass fraction in the ladle before pouring was measured using the Optima7 handheld flue gas analyzer, as shown in Table 1. The ingots after pouring were sampled and tested to examine the changes in gas content and Al content. The results are shown in Table 2.

[0107] Example 3

[0108] This embodiment provides an argon replacement device and a replacement method suitable for a truncated cone-shaped tundish.

[0109] In this embodiment, the truncated cone-shaped tundish can accommodate 60 tons of molten steel.

[0110] The replacement device consists of the following:

[0111] The long tube replacement device includes: a first air intake hose, a long straight elbow, a 90° elbow, a 270° elbow, a horizontal joint, and a vertical joint;

[0112] The short pipe replacement device comprises: a second air intake hose, a short straight elbow pipe, and a horizontal joint.

[0113] The dimensions of the components of the long tube replacement device and the short tube replacement device are as follows:

[0114] The inner diameters of the first air intake hose 1 and the second air intake hose 7, the long straight elbow 3, the short straight elbow 8, the 90° elbow 5, and the 270° elbow 6 in the long tube replacement device and the short tube replacement device are 22 mm, and the bending radius is 200 mm; the inner diameters of the horizontal joint 2 and the vertical joint 4 are both 26 mm;

[0115] The vertical length of the long straight curved pipe in the long pipe replacement device is H-300mm, where H is the height of the truncated cone-shaped tundish; the vertical length of the long straight curved pipe in the short pipe replacement device is 300mm;

[0116] The horizontal joint 2 and the vertical joint 4 are made of 6.5 mm thick stainless steel pipes.

[0117] The replacement method is:

[0118] S1. Assemble the replacement device and connect the gas source: before pouring, assemble the long tube replacement device and the short tube replacement device respectively according to the connection order and position relationship; place the assembled replacement device at the designated position of the tundish, wherein the first air inlet hose and the second air inlet hose are located outside the tundish and connected to the external gas source;

[0119] S2. Argon replacement before pouring: Open the external gas source connected to the first gas inlet hose and the second gas inlet hose, and introduce argon into the tundish. At the same time, use the long tube replacement device and the short tube replacement device to replace the argon in the tundish before receiving the refined molten steel. When the refining sliding nozzle is opened, close the external gas source connected to the long tube replacement device, and quickly withdraw the long tube replacement device from the tundish. The ventilation time before pouring is 20 minutes;

[0120] S3. Argon replacement during pouring: During the pouring process, keep the external gas source connected to the first air inlet hose closed and the external gas source connected to the second air inlet hose open, and use a short tube replacement device alone to perform gas replacement. When the pouring is completed, turn off the gas source. The argon gas flow time during the pouring process is 32 minutes.

[0121] The pressure of the argon outlet in the argon replacement device is 0.4Mpa; the flow rate of the argon replacement device is 45.2m 3 / h.

[0122] The oxygen mass fraction in the ladle before pouring was measured using the Optima7 handheld flue gas analyzer, as shown in Table 1. The ingots after pouring were sampled and tested to examine the changes in gas content and Al content. The results are shown in Table 2.

[0123] Embodiments 4 to 7

[0124] The argon replacement device and replacement method for the truncated cone-shaped tundish provided in this embodiment are the same as those in Embodiment 1, except that the argon outlet pressure, argon flow rate and replacement time are different. The specific parameters are shown in Table 1.

[0125] The oxygen mass fraction in the ladle before pouring was measured using an Optima7 handheld flue gas analyzer, as shown in Table 1. The ingot after pouring in Example 4 was sampled and tested to examine the changes in gas content and Al content. The results are shown in Table 2.

[0126] Comparative Example 1

[0127] The argon replacement device suitable for the truncated cone-shaped tundish provided in this embodiment is the same as that in Embodiment 1.

[0128] In this embodiment, the truncated cone-shaped tundish can accommodate 60 tons of molten steel.

[0129] The difference between the replacement method and Example 1 is that in step S2, only a short tube replacement device is used for replacement, and the replacement time is 15 minutes, and in step S3, the replacement time of the short tube replacement device is 32 minutes;

[0130] The pressure of the argon outlet in the argon replacement device is 0.2Mpa; the flow rate of the argon replacement device is 22.6m 3 / h.

[0131] The oxygen mass fraction in the ladle before pouring was measured using the Optima7 handheld flue gas analyzer, see Table 1.

[0132] Comparative Example 2

[0133] This embodiment provides an argon replacement device and a replacement method suitable for a truncated cone-shaped tundish.

[0134] In this embodiment, the truncated cone-shaped tundish can accommodate 60 tons of molten steel.

[0135] The replacement device consists of the following:

[0136] The long tube replacement device comprises: a first air intake hose, a long straight elbow and a horizontal joint;

[0137] The short pipe replacement device comprises: a second air intake hose, a short straight elbow pipe, and a horizontal joint.

[0138] The dimensions of the components of the long tube replacement device and the short tube replacement device are as follows:

[0139] The inner diameters of the first air intake hose 1 and the second air intake hose 7, the long straight elbow 3, and the short straight elbow 8 in the long tube replacement device and the short tube replacement device are 20 mm; the inner diameter of the horizontal joint 2 is 24 mm;

[0140] The vertical length of the long straight curved pipe in the long pipe replacement device is H-00mm, where H is the height of the truncated cone-shaped tundish; the vertical length of the long straight curved pipe in the short pipe replacement device is 200mm;

[0141] The horizontal joint 2 is made of 5 mm thick stainless steel pipe.

[0142] The replacement method and argon replacement parameters are the same as those in Example 1.

[0143] The oxygen mass fraction in the ladle before pouring was measured using the Optima7 handheld flue gas analyzer, see Table 1.

[0144] Comparative Example 3

[0145] This embodiment provides an argon replacement device and a replacement method suitable for a truncated cone-shaped tundish.

[0146] In this embodiment, the truncated cone-shaped tundish can accommodate 60 tons of molten steel.

[0147] The replacement device consists of the following:

[0148] The long tube replacement device includes: a first air intake hose, a long straight elbow, a 90° elbow, a 270° elbow, a horizontal joint, and a vertical joint;

[0149] The short pipe replacement device comprises: a second air intake hose, a short straight elbow pipe, and a horizontal joint.

[0150] The dimensions of the components of the long tube replacement device and the short tube replacement device are as follows:

[0151] The inner diameters of the first air intake hose 1 and the second air intake hose 7, the long straight elbow 3, the short straight elbow 8, the 90° elbow 5, and the 270° elbow 6 in the long tube replacement device and the short tube replacement device are 20 mm, and the bending radius is 400 mm; the inner diameters of the horizontal joint 2 and the vertical joint 4 are both 24 mm;

[0152] The vertical length of the long straight curved pipe in the long pipe replacement device is H-200mm, where H is the height of the truncated cone-shaped tundish; the vertical length of the long straight curved pipe in the short pipe replacement device is 200mm;

[0153] The horizontal joint 2 and the vertical joint 4 are made of 5 mm thick stainless steel pipes.

[0154] The replacement method and argon replacement parameters are the same as those in Example 1.

[0155] The oxygen mass fraction in the ladle before pouring was measured using the Optima7 handheld flue gas analyzer, see Table 1.

[0156] Comparative Example 4

[0157] This embodiment provides an argon replacement device and a replacement method suitable for a truncated cone-shaped tundish.

[0158] In this embodiment, the truncated cone-shaped tundish can accommodate 60 tons of molten steel.

[0159] The replacement device consists of the following:

[0160] The long tube replacement device includes: a first air intake hose, a long straight elbow, a 90° elbow, a 270° elbow, a horizontal joint, and a vertical joint;

[0161] The short pipe replacement device comprises: a second air intake hose, a short straight elbow pipe, and a horizontal joint.

[0162] The dimensions of the components of the long tube replacement device and the short tube replacement device are as follows:

[0163] The inner diameters of the first air intake hose 1 and the second air intake hose 7, the long straight elbow 3, the short straight elbow 8, the 90° elbow 5, and the 270° elbow 6 in the long tube replacement device and the short tube replacement device are 20 mm, and the bending radius is 100 mm; the inner diameters of the horizontal joint 2 and the vertical joint 4 are both 24 mm;

[0164] The vertical length of the long straight curved pipe in the long pipe replacement device is H-200mm, where H is the height of the truncated cone-shaped tundish; the vertical length of the long straight curved pipe in the short pipe replacement device is 200mm;

[0165] The horizontal joint 2 and the vertical joint 4 are made of 5 mm thick stainless steel pipes.

[0166] The replacement method and argon replacement parameters are the same as those in Example 1. During the replacement process in step S2, the long tube replacement device shakes severely.

[0167] The oxygen mass fraction in the ladle before pouring was measured using the Optima7 handheld flue gas analyzer, see Table 1.

[0168] Table 1 Argon replacement parameters and oxygen mass fraction in the ladle before pouring

[0169]

[0170] Table 2 Gas content and Al content of ingot after casting

[0171]

[0172] It can be seen from Table 1 that before pouring, the argon flow rate in the truncated cone shaped tundish argon replacement device and method has a certain influence on the replacement effect of the tundish. Within the allowable gas volume range, the larger the argon flow rate, the lower the oxygen mass fraction in the tundish. The present invention adopts a 270° elbow outlet form at the lower outlet of the long tube replacement device, which greatly improves the allowable gas volume range, thereby improving the replacement efficiency;

[0173] It can be seen from Comparative Example 1 and Implementation 1 that only replacement by a short tube replacement device before pouring will result in poor gas replacement effect in the tundish; it can be seen from Comparative Example 2 and Implementation 1 that the lower outlet of the long tube replacement device in Implementation 1 adopts a 270° elbow outlet, and the gas replacement in the tundish is more thorough; it can be seen from Comparative Example 3, Comparative Example 4 and Implementation 1 that the bending radius of the 270° elbow at the lower outlet of the long tube replacement device is too large or too small, which will cause poor gas replacement effect in the tundish.

[0174] It can be seen from Table 2 that, by using the replacement device of the present invention, under the premise of ensuring a suitable oxygen mass fraction before the tundish is poured, under the argon blowing flow condition of Example 2, the ingot sampling test results have the lowest increase in nitrogen content and the least burnout of Al content; during the pouring process, it is not appropriate to blow argon at too large or too small a flow rate. After the argon enters the tundish from the argon blowing short tube, it escapes from the core rod outlet, and at the position of the middle pouring port, there is a situation of air entrainment, which leads to the phenomenon described in the table;

[0175] The argon blowing pressure also has a certain impact on the gas flow. If the pressure is too high, the gas flow rate will be fast, which will disturb the poured steel flow and affect the replacement effect of the ladle.

[0176] In summary, the present invention implements long and short combined argon blowing devices on the truncated cone tundish, regulates the parameters of the replacement process, implements gas protection in the entire casting process, improves the quality of molten steel and reduces secondary oxidation of molten steel.

[0177] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A truncated cone tundish argon replacement device, characterized in that: It includes a long tube replacement device and a short tube replacement device; The long tube replacement device comprises a first air intake hose, a long straight elbow, a 90° elbow and a 270° elbow connected in sequence; the long straight elbow comprises a long straight elbow horizontal portion and a long straight elbow vertical portion; The first air intake hose is connected to the inlet of the horizontal part of the long straight elbow through a horizontal joint, the outlet of the vertical end of the long straight elbow is connected to the vertical end of the 90° elbow through a vertical joint, and the horizontal end of the 90° elbow is connected to the 270° elbow through a horizontal joint; The short pipe replacement device comprises a second air intake hose and a short straight elbow pipe connected by a horizontal joint, and the short straight elbow pipe comprises a short straight elbow horizontal portion and a short straight elbow vertical portion.

2. The replacement device according to claim 1, characterized in that Before pouring, the long tube replacement device and the short tube replacement device work simultaneously to introduce argon into the tundish; during the pouring process, the short tube replacement device works alone to introduce argon into the tundish.

3. The replacement device according to claim 1, characterized in that The calculated inner diameters of the first air intake hose, the second air intake hose, the long straight elbow, the short straight elbow, the 90° elbow, and the 270° elbow are a, a- calculated value of the inner diameter of the pipe, in mm; Q- is the argon gas flow rate, in m 3 / h; V- is the argon gas flow rate, in m / h; The actual inner diameters of the first air intake hose, the second air intake hose, the long straight elbow, the short straight elbow, the 90° elbow, and the 270° elbow are a±1 mm.

4. The replacement device according to claim 1, characterized in that The length of the vertical part of the long straight elbow is H-(200-300) mm, where H is the height of the truncated cone-shaped tundish.

5. The replacement device according to claim 2, characterized in that: In the long tube replacement device, the central plane where the 90° elbow is located is perpendicular to the central plane where the 270° elbow is located.

6. The replacement device according to claim 1, characterized in that The length of the vertical portion of the short straight elbow in the short pipe replacement device is 200mm-300mm, and the inner diameter of the 270° elbow is 200mm-300mm.

7. A method for replacing argon in a truncated cone tundish, using the argon replacement device according to any one of claims 1 to 6, characterized in that: The steps include: S1. Assemble the replacement device and connect the gas source: before pouring, assemble the long tube replacement device and the short tube replacement device respectively according to the connection order and position relationship; place the assembled replacement device at the designated position of the tundish, wherein the first air inlet hose and the second air inlet hose are located outside the tundish and connected to the external gas source; S2. Argon replacement before pouring: Open the external gas source connected to the first gas inlet hose and the second gas inlet hose, and introduce argon into the tundish. At the same time, use the long tube replacement device and the short tube replacement device to replace the argon in the tundish before receiving the refined molten steel. When the refining sliding nozzle is opened, close the external gas source connected to the long tube replacement device. The ventilation time before pouring is 15-20 minutes. After the ventilation is completed, quickly pull the long tube replacement device out of the tundish; S3. Argon replacement during pouring: During the pouring process, keep the external gas source connected to the first gas inlet hose closed and the external gas source connected to the second gas inlet hose open, and use a short tube replacement device alone to perform gas replacement. When the pouring is completed, turn off the gas source.

8. The argon replacement method according to claim 7, characterized in that: The long tube replacement device is placed in an area with a radius of 85mm-100mm around the truncated cone-shaped middle core rod; the short tube replacement device is placed at a distance of ≤400mm from the edge of the cover hole.

9. The argon replacement method according to claim 7, characterized in that: The pressure of the argon outlet in the argon replacement device is 0.2-0.4Mpa.

10. The argon replacement method according to claim 7, characterized in that: The flow rate of argon in the argon replacement device is 22.6-45.2m 3 / h.

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