An ultrapure casting filter device for a vacuum induction furnace

Abstract

This utility model discloses an ultrapure casting slag filter device for a vacuum induction furnace, comprising a steel plate reinforced outer shell with an open top, and an internal lining for a flow-injection zone, a casting zone lining opposite to the flow-injection zone lining, and a U-shaped groove between the casting zone lining and the flow-injection zone lining. The U-shaped groove is a detachable and replaceable structure, with its two opposite surfaces corresponding to and fitting one-to-one with the casting zone lining and the flow-injection zone lining, maintaining the same horizontal bottom surface. A second slag-blocking baffle is suspended along the length of the U-shaped groove, with its lower edge lower than the upper edge of the U-shaped groove and forming a steel flow gap with the bottom of the U-shaped groove. A casting nozzle is provided on the casting zone lining, and the bottom of the casting nozzle penetrates the bottom of both the casting zone lining and the steel plate reinforced outer shell. This utility model can improve the slag-blocking effect and increase the purity of molten steel.

Description

Technical Field

[0001] This utility model relates to the field of vacuum induction melting and casting technology, specifically to an ultrapure casting filter device for a vacuum induction furnace. Background Technology

[0002] With the rapid development of the aerospace and defense industries, the requirements for high quality and high performance of special steel are constantly increasing. Controlling non-metallic inclusions in steel is one of the important factors affecting the stability of the quality and performance of domestically produced steel. The size and quantity of inclusions have a significant impact on fatigue life. Currently, high-end special steel in China mainly adopts a dual-process smelting method combining vacuum induction and vacuum arc remelting to improve the purity of the steel.

[0003] Currently, vacuum induction furnaces refine and degas molten steel under vacuum conditions, then pour it into ingot molds through slag-filtering devices such as funnels and troughs. The lining of the melting crucible is typically made of refractory material. The impact of large metal blocks being added to the furnace on the refractory lining, along with the erosion caused by the molten steel under electromagnetic stirring, leads to refractory material spalling and contamination of the molten steel. Under high temperatures, the reaction between the molten steel and oxides in the refractory material forms secondary oxide inclusions, and the raw materials may carry small amounts of inclusions. These various composite inclusions accumulate and float to the surface of the molten steel, forming significant amounts of slag and oxide film. If the slag-filtering system is poorly designed during pouring, slag and oxide film can flow into the electrode mold with the molten steel, severely reducing the purity of the electrode billet. In the subsequent vacuum arc remelting process, these impurities negatively impact the stability of the arc remelting process, making complete removal impossible and significantly increasing the risk of inclusion defects during steel inspection, thus greatly affecting the steel's performance.

[0004] The casting funnel / quench is an important slag filtering device in steel manufacturing that connects the smelting crucible and the electrode mold. As the last refractory container before the molten steel is injected into the electrode mold, the shedding and wear of the refractory material can cause the refined molten steel to be contaminated again during the casting process. Therefore, slag blocking and steel tapping is an important part of ensuring metallurgical purity.

[0005] like Figure 3 The diagram shown is a schematic of an existing slag-blocking casting channel for a vacuum induction furnace, including a long channel 13, a channel lining 14, a first slag-blocking baffle 15, a slag-blocking dam 16, and an existing casting nozzle 17. However, the following problems exist in the casting slag filter technology: (1) At present, the length of the flow channel is usually greater than 2 meters. The long length increases the time and area of ​​the refractory lining being washed by the molten steel, and increases the probability of inclusions.

[0006] (2) Currently, the trough is equipped with a first slag baffle 15 and a slag dam 16 to prevent slag from flowing into the pouring area. The height of the slag dam 16 is generally 50-60 mm, and the distance from the molten steel impact zone is about 800 mm. When the molten steel reaches about 40 L, the molten steel level needs to exceed the height of the slag dam by a certain amount for the slag dam 16 to effectively prevent the floating slag on the molten steel surface from flowing into the pouring nozzle area, thus achieving the purpose of slag filtering. Since sufficient molten steel needs to be replenished, the slag-blocking failure time is relatively long, affecting the slag-blocking effect. On the other hand, if the flow rate of molten steel poured from the crucible into the trough is not properly controlled, the molten steel flow rate will be too large and directly overflow the first slag baffle 15, which will lead to slag-blocking failure. In addition, when the molten steel supply is insufficient, the liquid level will drop. If the liquid level drops to below the height of the slag dam, it will also cause slag-blocking failure, increasing the difficulty of the pouring operation for workers and greatly increasing the risk of inclusion.

[0007] (3) At present, the first slag baffle 15 and the slag dam 16 of the flow channel are constructed with magnesium aluminum refractory bricks and the refractory bricks are bonded and fixed with refractory mortar. The first slag baffle 15 and the slag dam 16 will wear off due to high-speed scouring of molten steel or chemical corrosion, affecting the slag-blocking effect.

[0008] (4) At present, the lining 14 of the flow channel is constructed by ramming magnesium-aluminum refractory material, which has poor seismic resistance and heat resistance. Under the scouring of high-temperature molten steel, the refractory material is easy to fall into the molten steel, affecting the purity of the steel.

[0009] In summary, it can be concluded that at present, the refractory materials and oxide films floating on the surface of molten steel during the casting process, as well as the refractory materials brought in by the trough during the casting process, cannot be completely removed, and true ultrapure smelting cannot be achieved. Utility Model Content

[0010] The technical problem to be solved by this utility model is to provide an ultrapure casting slag filter device for vacuum induction furnaces, so as to solve the problem of slag and oxide film being carried into the molten steel during the casting process of vacuum induction furnaces, thereby improving the slag blocking effect and improving the purity of molten steel.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows.

[0012] An ultrapure casting filter device for a vacuum induction furnace includes a steel plate reinforced outer shell with an open top. Inside the steel plate reinforced outer shell are a flow inlet liner, a casting liner opposite to the flow inlet liner, and a U-shaped groove located between the casting liner and the flow inlet liner. The U-shaped groove is a detachable and replaceable structure, with its two opposite faces corresponding to and fitting one-to-one with the casting liner and the flow inlet liner, maintaining the same horizontal bottom surface. A second slag-blocking baffle is suspended along the length of the U-shaped groove, with its lower edge lower than the upper edge of the U-shaped groove and forming a steel flow gap with the bottom of the U-shaped groove. A casting nozzle is provided on the casting liner, penetrating both the casting liner and the bottom of the steel plate reinforced outer shell.

[0013] Preferably, the steel plate reinforced shell is a rectangular structure welded from steel plates. The lining of the injection zone, the U-shaped groove, and the lining of the casting zone are arranged sequentially along the length of the steel plate reinforced shell. The top of the second slag baffle is flush with the top of the steel plate reinforced shell, the lining of the injection zone, and the lining of the casting zone.

[0014] Preferably, the inner wall of the steel plate reinforced shell and the gap positions at the bottom opposite to the lining of the injection zone and the lining of the casting zone are covered with a lining for supporting and heat insulation. The lining of the injection zone and the lining of the casting zone are respectively covered on the lining. The bottom of the U-shaped groove is in contact with the steel plate reinforced shell, and the two opposite U-shaped ends of the U-shaped groove are in contact with the corresponding side lining.

[0015] Preferably, the U-shaped groove is bonded to the steel plate reinforced outer shell, the lining, the lining of the injection zone and the lining of the casting zone using an internal mud-mouth construction process.

[0016] Preferably, the bottom of the steel plate reinforced outer shell is provided with a disassembly hole at the position opposite to the bottom of the U-shaped groove, so as to facilitate the removal of the U-shaped groove and realize the detachment of the U-shaped groove.

[0017] Preferably, the pouring nozzle is a conical opening that is wider at the top and narrower at the bottom.

[0018] Preferably, the inner corner of the U-shaped groove is a rounded transition, and the upper edge of the U-shaped groove is on the same horizontal plane as the bottom upper surface of the casting area lining and the flow injection area lining.

[0019] Due to the adoption of the above technical solutions, the technical progress achieved by this utility model is as follows: This invention utilizes a reinforced steel plate outer shell, a lining in the pouring zone, a U-shaped groove, a second slag-blocking baffle, and a lining in the casting zone. The U-shaped groove and second slag-blocking baffle design significantly reduce the volume of molten steel required for effective slag blocking, shortening the slag-blocking time and greatly improving the slag-blocking effect. It also eliminates the influence of improper control of the molten steel flow from the crucible, which could lead to slag being carried into the casting zone, resulting in virtually slag-free steel tapping. This significantly improves the purity of the molten steel and ensures the stability of metallurgical quality. Furthermore, the U-shaped groove and second slag-blocking baffle, as key slag-blocking components, are designed as a detachable and replaceable structure. This ensures the slag-blocking effect during re-pouring, and the partial replacement method extends the overall service life of the trough lining, reducing the consumption of refractory materials. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of the present invention; Figure 2 This is a top view of the present invention; Figure 3 This is a schematic diagram of the slag-blocking casting channel used in an existing vacuum induction furnace.

[0021] Among them: 1. crucible, 2. slag, 3. steel plate reinforced outer shell, 4. lining, 5. lining of the pouring zone, 6. U-shaped groove, 7. second slag baffle, 8. steel flow gap, 9. lining of the pouring zone, 10. pouring nozzle, 11. disassembly hole, 12. steel ingot mold, 13. long flow channel, 14. flow channel lining, 15. first slag baffle, 16. slag dam, 17. existing pouring nozzle. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] A vacuum induction furnace ultrapure casting filter device, combined with Figures 1 to 2As shown, the device is installed in the casting chamber of a vacuum induction furnace, where molten steel flows into the crucible 1 when it is tilted. The device includes a steel plate reinforced outer shell 3. Inside the steel plate reinforced outer shell 3, there are a flow zone lining 5, a U-shaped groove 6, and a casting zone lining 9. The flow zone lining 5 and the casting zone lining 9 serve as flow channel linings and are arranged opposite each other inside the steel plate reinforced outer shell 3. The U-shaped groove 6 is located between the flow zone lining 5 and the casting zone lining 9. The U-shaped groove 6 is a detachable and replaceable structure. The two opposite surfaces of the U-shaped groove 6 correspond to and fit one-to-one with the casting zone lining 9 and the flow zone lining 5, and their relative heights are maintained at the same horizontal bottom surface. A second slag-blocking baffle 7 is suspended along the length of the U-shaped groove 6. The second slag-blocking baffle 7 is built and fitted onto the flow zone lining 5 and the casting zone lining 9. The lower edge of the second slag-blocking baffle 7 is lower than the upper edge of the U-shaped groove 6 by a certain height, and a steel flow gap 8 is formed between the second slag-blocking baffle 7 and the bottom of the U-shaped groove 6. A pouring gate 10 is provided on the inner lining 9 of the pouring area, and the pouring gate 10 penetrates the bottom of the inner lining 9 of the pouring area and the steel plate reinforced outer shell 3. A steel ingot mold 12 is provided below the steel plate reinforced outer shell 3, and the steel ingot mold 12 is placed centered on the circumference of the pouring gate 10.

[0024] Specifically, the steel plate reinforced outer shell 3 is a rectangular structure with an open top, welded from steel plates, which ensures that the lining 5 in the flow zone and the lining 9 in the casting zone do not crack or deform during high-temperature casting. Specifically, the steel plate reinforced outer shell 3 is a rectangular structure welded from 30mm thick steel plates, with a length of 2m and a height of 2.3m.

[0025] The lining 5 of the flow zone, the U-shaped groove 6, and the lining 9 of the casting zone are arranged sequentially along the length of the steel plate reinforced outer shell 3. The lining 5 of the flow zone and the lining 9 of the casting zone serve to resist high temperature and corrosion. The thickness is about 30mm. A 100-200mm gap is reserved between the lining 5 of the flow zone and the lining 9 of the casting zone for inserting the U-shaped groove 6. The lining 5 of the flow zone is made of refractory castable in one piece by ramming and sintering, and is made of alumina-magnesia refractory. The lining 9 of the casting zone is made of refractory castable in one piece by ramming and sintering, and is made of corundum refractory castable. The matching pouring nozzle 10 is a conical nozzle that is wider at the top and narrower at the bottom. It is also made of corundum. The nozzle size is reasonably matched according to the steel volume and the casting ingot shape.

[0026] The inner walls of the steel plate reinforced outer shell 3, as well as the seams at the bottom opposite to the linings 5 ​​and 9 of the injection zone, are covered with a lining 4. The lining 4 is approximately 20 mm thick and serves as support and insulation. The linings 5 ​​and 9 of the injection zone are respectively covered on the lining 4. The bottom of the U-shaped groove 6 is fitted to the steel plate reinforced outer shell 3, and the two opposite U-shaped ends of the U-shaped groove 6 are respectively fitted to the corresponding side linings 4.

[0027] To secure the U-shaped groove 6, the U-shaped groove 6 is bonded to the steel plate reinforced outer shell 3, the lining 4, the inner lining of the injection zone 5, and the inner lining of the casting zone 9 using an inner mud-mouth construction process. This prevents the refractory mortar from coming into direct contact with the molten metal and falling off due to high-temperature erosion.

[0028] In order to make the U-shaped groove 6 detachable, a disassembly hole 11 is provided at the bottom of the steel plate reinforced outer shell 3 at the position opposite to the bottom of the U-shaped groove 6. Using the disassembly hole 11, a mold ejector tool can be used to eject the U-shaped groove 6 from the bottom of the flow channel, ensuring that the U-shaped groove 6 can be removed smoothly without damaging other parts.

[0029] The top of the second slag-blocking baffle 7 is flush with the top of the steel plate reinforced outer shell 3, the lining of the injection zone 5, and the lining of the casting zone 9. Both the second slag-blocking baffle 7 and the U-shaped groove 6 are specially made corundum refractory brick molded parts. The depth of the U-shaped groove 6 is 90mm, and its inner corners are rounded. The upper edge of the U-shaped groove 6 is on the same horizontal plane as the bottom upper surface of the lining of the injection zone 5 and the lining of the casting zone 9. The vertical distance between the bottom upper surface of the lining of the injection zone 5 and the lining of the casting zone and the lower edge of the second slag-blocking baffle 7 is 60mm (the depth of the second slag-blocking baffle 7 inserted into the U-shaped groove 6). The height of the steel flow gap 8 is 30mm. The depth of the U-shaped groove 6 is the insertion depth of the second slag-blocking baffle 7 plus the height of the steel flow gap 8.

[0030] After the assembly and construction of this utility model are completed, it is baked at 1000±10℃ to ensure the sintering effect, and then sent to a vacuum casting chamber to await tapping. Once the chemical composition, gas and residual elements of the molten metal are controlled and the tapping temperature meets the standards, the casting operation is carried out.

[0031] The working principle of this utility model is as follows: The crucible 1 is tilted, and the molten steel begins to flow into the flow channel. The molten steel mixes with the slag 2 and flows into the lining 5 of the pouring zone. As the tilt angle of the crucible 1 increases, the flow rate of the molten steel increases and the depth of the molten pool increases. Under the action of buoyancy, the slag 2 floats to the surface of the molten steel and forms a slag layer. Before the molten steel flows to the second slag baffle 7, the surface slag 2 is blocked on the left side by the second slag baffle 7 and cannot continue to flow forward. The pure molten steel below the slag enters the lining 9 of the pouring zone through the U-shaped groove 6, and the flow rate of the molten steel flowing through the U-shaped groove 6 is greater than the flow rate of the pouring nozzle 10 to ensure a smooth pouring process.

[0032] At the end of the steel casting process, the remaining amount of molten steel gradually decreases, and the depth of the molten metal pool in the lining 5 of the pouring zone gradually decreases. The molten steel level drops to be level with the upper edge of the U-shaped groove 6. Due to the pressure, the molten steel will hardly flow into the lining 9 of the pouring zone through the U-shaped groove 6 anymore, and it is close to a state of cessation. Since the steel flow gap 8 is lower than the upper edge of the U-shaped groove 6, the slag 2 on the surface of the molten steel is blocked by the second slag baffle 7 and will not flow to the right side of the second slag baffle 7 through the steel flow gap 8. This effectively improves the removal rate of inclusions, ensures the purity of the poured molten steel, and greatly reduces the probability of steel failing the flaw detection due to slag inclusions.

[0033] After a single pour is completed, the U-shaped groove 6 and the second slag baffle 7 structure are the areas with the most severe slag adhesion. The inside of the U-shaped groove 6 is filled with solidified molten metal, and a large amount of slag adheres to the right side of the second slag baffle 7, which is difficult to clean and affects the purity of the molten steel poured next. Since the U-shaped groove 6 and the flow channel are separate structures, at this time, it is only necessary to separate the U-shaped groove 6 from the flow channel and remove it through the disassembly hole 11. Remove the second slag baffle 7, clean the residue and impurities on the inner wall of the flow channel and the pouring area, and repair it. Then replace the new U-shaped groove 6 and build a new second slag baffle 7 for use in the next steel pour.

[0034] This invention effectively reduces the inclusion content in steel ingots during vacuum steel casting, achieving a high slag-blocking effect. The detachable U-shaped groove 6 and the second slag-blocking baffle 7 structure ensure that only the key slag-blocking parts are replaced without replacing the entire refractory material of the trough inner wall. This guarantees the slag-blocking effect of the trough during recasting, saves refractory material, extends the overall service life of the trough lining, and reduces refractory material consumption. Simultaneously, the U-shaped groove 6 and the second slag-blocking baffle 7 are made of specially formulated corundum refractory bricks, improving refractory quality, reducing the possibility of refractory spalling due to erosion of the trough lining by molten steel, and enhancing the purity of the steel ingot.

[0035] This invention allows for an overall length design of 2 meters, which effectively shortens the molten pool formation time and the steel flow path. When the molten steel storage volume is about 10 liters, it can flow into the U-shaped groove. The second slag-blocking baffle blocks the floating slag, greatly improving the casting and slag-blocking efficiency. It is easy to operate and does not rely on the operator's personal experience. On the other hand, it reduces the amount of refractory material used, effectively reducing the probability of the inner lining refractory material falling off due to molten steel washing. In addition, it makes it easier to achieve low-temperature casting, which can effectively reduce the degree of segregation of the electrode billet.

[0036] The lining 5 in the flow zone and the lining 9 in the casting zone of this invention are integrally sintered refractory castables, which ensures the integrity of the structure and reduces the probability of refractory mortar falling off due to direct contact with molten metal.

Claims

1. A device for ultrapure casting filter residue in a vacuum induction furnace, characterized in that: The structure includes a steel plate reinforced outer shell (3) with an open top. Inside the steel plate reinforced outer shell (3) are a sprue liner (5), a casting liner (9) opposite to the sprue liner (5), and a U-shaped groove (6) located between the casting liner (9) and the sprue liner (5). The U-shaped groove (6) is a detachable and replaceable structure, with its two opposite faces corresponding to the casting liner (9) and the sprue liner (5), respectively. The two sides are connected and their relative heights are kept at the same horizontal bottom surface; a second slag baffle (7) is suspended in the middle of the U-shaped groove (6) along the length direction, and the lower edge of the second slag baffle (7) is lower than the height of the upper edge of the U-shaped groove (6) and forms a steel flow gap (8) between it and the bottom of the U-shaped groove (6); a pouring water nozzle (10) is opened on the inner lining (9) of the casting area, and the pouring water nozzle (10) penetrates the bottom of the inner lining (9) of the casting area and the steel plate reinforced shell (3).

2. The ultrapure casting filter slag device for a vacuum induction furnace according to claim 1, characterized in that: The steel plate reinforced shell (3) is a rectangular structure welded from steel plates. The lining (5), U-shaped groove (6) and casting area lining (9) are arranged sequentially along the length of the steel plate reinforced shell (3). The top of the second slag baffle (7) is flush with the top of the steel plate reinforced shell (3), the lining (5) and the casting area lining (9).

3. The ultrapure casting filter slag device for a vacuum induction furnace according to claim 1, characterized in that: The inner wall of the steel plate reinforced shell (3) and the gap position at the bottom opposite to the lining of the injection zone (5) and the lining of the casting zone (9) are covered with a lining (4) for supporting and heat insulation. The lining of the injection zone (5) and the lining of the casting zone (9) are respectively covered on the lining (4). The bottom of the U-shaped groove (6) is in contact with the steel plate reinforced shell (3), and the two opposite U-shaped ends of the U-shaped groove (6) are in contact with the corresponding side lining (4).

4. The ultrapure casting filter device for a vacuum induction furnace according to claim 3, characterized in that: The U-shaped groove (6) is bonded to the steel plate reinforced shell (3), the lining (4), the lining of the injection zone (5), and the lining of the pouring zone (9) using the inner mud gate construction process.

5. The ultrapure casting filter slag device for a vacuum induction furnace according to claim 4, characterized in that: The bottom of the steel plate reinforced outer shell (3) is provided with a disassembly hole (11) at the position opposite to the bottom of the U-shaped groove (6) to facilitate the removal of the U-shaped groove (6) so that the U-shaped groove (6) can be disassembled.

6. The ultrapure casting filter device for a vacuum induction furnace according to claim 1, characterized in that: The pouring nozzle (10) is a conical opening that is wider at the top and narrower at the bottom.

7. The ultrapure casting filter device for a vacuum induction furnace according to claim 1, characterized in that: The inner corner of the U-shaped groove (6) is an arc-shaped transition rounded corner, and the upper edge of the U-shaped groove (6) is on the same horizontal plane as the bottom upper surface of the casting area lining (9) and the injection area lining (5).

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