A gas protection device for casting a steel casting and a casting method

Abstract

The application provides a gas protection device for casting steel parts and a casting method, and relates to the technical field of metal material casting. The gas protection device for casting steel parts comprises a refractory part, an inner hole for passing molten steel, and a groove on the top end surface of the refractory part. The refractory part is arranged on a pouring table, and the lower end of the inner hole corresponds to the pouring cup. A sealing assembly is embedded in the groove, which surrounds the liquid outlet hole of the ladle and contacts the bottom of the ladle during pouring to achieve sealing through compression deformation. An air cavity is arranged in the refractory part, which is provided with an air inlet for introducing protective gas and an air outlet. The air outlet is arranged towards the inner hole to spray protective gas into the inner hole. The application can effectively prevent the oxidation and burning loss of active elements such as chromium, molybdenum, vanadium and niobium in the molten steel and reduce the cost.

Description

Technical Field

[0001] This invention relates to the field of metal casting technology, and more specifically, to a gas protection device and casting method for casting steel parts. Background Technology

[0002] CB2 steel (containing elements such as chromium, molybdenum, vanadium, and niobium) is a key material for manufacturing core components such as cylinders and valves in ultra-supercritical power units. Its casting quality directly affects the progress of clean coal power technology upgrades. During the pouring of molten steel at temperatures exceeding 1550°C, exposure to air causes active elements to continuously react with oxygen, generating oxides and inclusions. This not only causes surface defects such as wrinkles on the casting but also severely deteriorates its mechanical properties, becoming a source of crack initiation and propagation during use. For large castings, extensive surface oxidation leads to high costs for subsequent welding repairs and may even result in the scrapping of the entire piece, causing significant economic losses. Therefore, taking effective anti-oxidation measures during the pouring process to ensure the purity of the molten steel is crucial for guaranteeing the quality of large, high-end castings.

[0003] To address the aforementioned oxidation problem, the most thorough approach in related technologies is overall argon purging protection, which involves placing the melting furnace, gating system, and mold cavity together in a sealed argon-purging chamber. However, this method requires huge equipment investment and incurrs high operating costs. Furthermore, for large castings, maintaining high purity and uniformity of argon gas within a large space is extremely difficult, resulting in massive argon gas consumption. Another more economical method is local argon blowing protection, which involves placing a protective cover between the pouring cup and the ladle and introducing argon gas. However, the protective devices in these technologies generally suffer from poor sealing performance. The lack of an effective sealing structure between the bottom of the ladle and the protective device allows air to easily enter the protected area, causing argon gas to easily escape. This not only makes it difficult to guarantee argon gas purity but also requires a continuous supply of large amounts of gas, increasing production costs and affecting the stability of casting quality. Summary of the Invention

[0004] The problem to be solved by this invention is at least one of the following technical issues: poor sealing between the bottom of the ladle and the protective device, resulting in air mixing, argon gas leakage, difficulty in forming a stable inert gas protective atmosphere, and huge argon gas consumption, leading to high costs.

[0005] To address the aforementioned problems, in a first aspect, the present invention provides a gas protection device for casting steel parts, comprising: a refractory component having an inner hole for molten steel to pass through, and a groove on its top end face; the refractory component being disposed on a pouring platform, and the lower end of the inner hole corresponding to the pouring cup; a sealing assembly embedded in the groove, used to surround the outlet hole of the ladle and contact the bottom of the ladle during casting, so as to achieve sealing through compression deformation; and a gas chamber disposed within the refractory component, the gas chamber having an inlet for introducing protective gas and an outlet, the outlet being disposed facing the inner hole for spraying protective gas into the inner hole.

[0006] Optionally, the sealing component is fitted into the groove, the radial dimension of the sealing component is adapted to the radial dimension of the groove, the axial height of the sealing component is greater than the depth of the groove, and the sealing component is used to contact the bottom of the ladle during casting and achieve sealing through compression deformation.

[0007] Optionally, the sealing assembly includes an annular asbestos ring, the outer diameter and inner diameter of which are adapted to the outer diameter and inner diameter of the groove, respectively, and the annular asbestos ring is embedded in the groove.

[0008] Optionally, the inner hole, the annular asbestos ring, and the pouring cup are coaxially arranged.

[0009] Optionally, the air chamber is formed by bending a metal tube. The air chamber includes an annular air collecting component. The air inlet is disposed on the air collecting component and connected to an external air source through an air inlet pipe. Multiple air outlets are provided, and each air outlet is provided with an air outlet pipe.

[0010] Optionally, the protective gas in the gas collecting device flows in one direction, and the multiple gas outlets are evenly distributed circumferentially. The gas flow direction at the connection between the gas collecting device and the gas outlet pipe is set at an obtuse angle to the gas outlet direction of the corresponding gas outlet pipe.

[0011] Optionally, the outlet end of the vent pipe does not extend beyond the inner wall of the refractory component.

[0012] Optionally, the refractory component is a refractory brick.

[0013] Optionally, the gas protection device for casting steel parts further includes an outer protective shell covering the outer surface of the refractory part, the outer protective shell being provided with lifting rings for hoisting, and the gas inlet pipe extending from inside the refractory part to outside the outer protective shell.

[0014] The beneficial effects of the gas protection device for casting steel parts of the present invention are as follows: by setting a refractory part as the main structure, its inner hole forms a steel flow channel, and the lower end of the inner hole matches the pouring port of the pouring cup, ensuring that the molten steel falls accurately into the pouring cup; a groove is set on the top end face of the refractory part for embedding a sealing component, which surrounds the outlet hole of the ladle and contacts the bottom of the ladle during pouring to form a sealed space; at the same time, a gas cavity is set inside the refractory part, and protective gas is introduced through the gas inlet and sprayed out towards the inner hole through the gas outlet, so that the protective gas fills the inner hole space. The aforementioned structure works synergistically. During the steel pouring process, the sealing component, embedded within the groove, forms a tight fit with the inner wall of the groove, constituting the first sealing interface. As the ladle descends, the sealing component contacts the bottom of the ladle and compresses under pressure to achieve a seal, filling the microscopic gap between the bottom of the ladle and the refractory components, forming a second sealing interface. This achieves a reliable double seal, effectively preventing external air intrusion and significantly reducing argon waste caused by leakage. The gas chamber continuously sprays protective gas into the inner hole, forming a stable inert gas barrier within the inner hole, effectively isolating the molten steel from air. The synergistic effect of the double seal and the inert gas barrier effectively prevents the oxidation and burning of reactive elements such as chromium, molybdenum, vanadium, and niobium in the molten steel, avoiding oxide inclusions and surface wrinkling defects, thereby improving the mechanical properties and internal purity of the casting. Simultaneously, the device has a compact structure, eliminating the need for a large argon-filling chamber, significantly reducing equipment investment costs; the excellent sealing performance reduces argon consumption, lowering operating costs.

[0015] In a second aspect, the present invention also provides a casting method based on a gas protection device for casting steel parts as described in any of the preceding claims, comprising: The surface of the sprue is smoothed, and the sprue cup is placed on the sprue. The refractory component is then placed on the sprue, with the lower end of the inner hole of the refractory component aligned with the pouring port of the sprue cup. The sealing component is then embedded in the groove of the refractory component. The ladle is then lifted so that the liquid outlet of the ladle is aligned with the sprue cup. Before pouring, protective gas is introduced through the air inlet of the air chamber, so that the protective gas flows through the air outlet of the air chamber to the inner hole, thereby venting the air in the inner hole, lowering the height of the ladle, and making the sealing assembly surround the liquid outlet of the ladle and contact the bottom of the ladle, so as to achieve a seal through compression deformation; while the protective gas is continuously introduced, the molten steel in the ladle is poured into the pouring cup through the inner hole.

[0016] The casting method provided by this invention first precisely aligns the lower end of the inner hole of the refractory component with the pouring port of the pouring cup to ensure that the molten steel falls accurately into the pouring cup and prevents splashing. Before casting, protective gas is introduced to purge the air from the inner hole, and then the ladle is lowered to press the sealing component tightly against the bottom of the ladle, forming a sealed argon-protected space. Casting is carried out while the protective gas is continuously introduced, so that the molten steel is always surrounded by an inert gas barrier as it flows through the inner hole, effectively isolating it from air. Through the synergistic cooperation of the above steps, the technical problem of easy oxidation of high alloy steel castings such as CB2 during the casting process is effectively solved, preventing the oxidation and burning loss of active elements such as chromium, molybdenum, vanadium, and niobium, significantly reducing surface wrinkling defects and internal oxide inclusions of the casting, and improving the mechanical properties and purity of the casting. At the same time, this method is simple to operate, has good compatibility with existing bottom-sink casting processes, does not require major modifications to existing equipment, reduces production costs, and improves the yield and quality stability of large high-end castings. Attached Figure Description

[0017] Figure 1 A three-dimensional schematic diagram of a gas protection device for casting steel parts in an embodiment of the present invention is shown. Figure 1 ; Figure 2 A three-dimensional schematic diagram of a gas protection device for casting steel parts in an embodiment of the present invention is shown. Figure 2 ; Figure 3 A schematic diagram illustrating the application scenario of the gas protection device for casting steel parts according to an embodiment of the present invention is shown; Figure 4 A schematic diagram of the refractory component in an embodiment of the present invention is shown; Figure 5 A top view of the sealing assembly in an embodiment of the present invention is shown; Figure 6 A schematic diagram of the sealing assembly in an embodiment of the present invention is shown; Figure 7 A schematic diagram of the air cavity inside the refractory component in an embodiment of the present invention is shown; Figure 8 A schematic diagram of the air cavity structure in an embodiment of the present invention is shown; Figure 9 This shows a front view schematic diagram of the external protective shell in an embodiment of the present invention; Figure 10 A top view of the external protective shell in an embodiment of the present invention is shown.

[0018] Explanation of reference numerals in the attached figures: 1. Refractory component; 101. Groove; 2. Gas cavity; 21. Gas collection component; 22. Gas outlet pipe; 23. Gas inlet pipe; 3. Outer protective shell; 4. Sprue platform; 5. Gas filling connector; 6. Sealing component; 7. Sprue cup; 8. Steel ladle; 9. Inner hole. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] In the description of this specification, references to terms such as "embodiment," "one embodiment," and "one implementation" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or implementation is included in at least one embodiment or illustrative implementation of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or implementation. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or implementations.

[0021] Reference Figure 1 , Figure 2 and Figure 3 As shown, this embodiment of the invention proposes a gas protection device for casting steel parts, comprising: Refractory component 1, having an inner hole 9 for molten steel to pass through, and a groove 101 on its top end face, the refractory component 1 is used to be installed on the pouring platform 4, and the lower end of the inner hole 9 corresponds to the pouring cup 7; sealing component 6, embedded in the groove 101, is used to surround the liquid outlet of the ladle 8 and contact the bottom of the ladle 8 during pouring, so as to achieve sealing through compression deformation; gas chamber 2, provided in the refractory component 1, the gas chamber 2 has an air inlet for introducing protective gas and an air outlet, the air outlet is arranged facing the inner hole 9, and is used to spray protective gas into the inner hole 9.

[0022] Specifically, the refractory component 1, as the main structure of the device, is made of high-temperature resistant material and can withstand the radiant heat and erosion of molten steel at a temperature of at least 1500°C. The refractory component 1 has an inner hole 9 for the passage of molten steel, which forms a vertical channel for the flow of molten steel. In use, the refractory component 1 is placed on the pouring platform 4 equipped with the pouring cup 7. The lower end of the inner hole 9 matches the pouring opening of the pouring cup 7 to achieve correspondence between the two, ensuring that the molten steel flowing from the ladle 8 can accurately fall into the pouring cup 7, avoiding splashing or deviating of the molten steel. Meanwhile, the top end face of the refractory component 1 is provided with a groove 101 for embedding the sealing component 6, providing a structural basis for subsequent sealing. This structural design ensures the smooth flow of molten steel and provides a reliable support platform for the sealing and gas path structure. Taking the production of the ultra-high pressure inner cylinder CB2 stainless steel casting as an example, the refractory component 1 adopts a ring structure made of white corundum refractory bricks, with its inner hole 9 vertically penetrating through, matching the pouring port size of the pouring cup 7. The inner diameter of the inner hole 9 is slightly larger than or equal to the pouring port size.

[0023] The sealing component 6 is embedded in the groove 101, forming a tight fit with the inner wall of the groove 101 to constitute the first sealing interface, preventing gas leakage from the contact surface. The sealing component 6 is located on the top end face of the refractory component 1. When the ladle 8 is lowered by the hoisting trolley, the bottom of the ladle 8 contacts the sealing component 6. Under pressure, the sealing component 6 compresses and deforms to achieve a seal, filling the micro-gap between the bottom of the ladle 8 and the refractory component 1, forming the second sealing interface, and achieving deformation sealing. Alternatively, the sealing component 6 can also use an annular graphite gasket, an annular ceramic fiber gasket, or an annular flexible metal sealing ring, etc., which also achieve reliable sealing through embedding and deformation. This deformation can also be elastic deformation.

[0024] The gas chamber 2 is located inside the refractory component 1 and around the inner hole 9, forming, for example, an annular gas channel. The gas chamber 2 has an inlet for introducing protective gas and an outlet facing the inner hole 9. Before and during pouring, protective gases such as argon enter the gas chamber 2 through the inlet and are ejected towards the inner hole 9 through the outlet, filling the space of the inner hole 9 with protective gas. This structural design enables the protective gas to form a continuous and stable inert gas barrier around the molten steel column, effectively isolating the molten steel from the air and preventing oxidation reactions caused by contact with oxygen during the flow process, effectively protecting the active elements in the molten steel from being burned off.

[0025] In this embodiment, a refractory component 1 is set as the main structure, and its inner hole 9 forms a channel for molten steel flow. The lower end of the inner hole 9 matches the pouring port of the pouring cup 7 to ensure that the molten steel falls accurately into the pouring cup. A groove 101 is set on the top end face of the refractory component 1 for embedding a sealing component 6. The sealing component 6 surrounds the liquid outlet of the ladle 8 and contacts the bottom of the ladle 8 during pouring to form a sealed space. At the same time, an air chamber 2 is set inside the refractory component 1. Protective gas is introduced through the air inlet and sprayed out towards the inner hole 9 through the air outlet, so that the protective gas fills the space of the inner hole 9. The aforementioned structures work synergistically. During the steel pouring process, the sealing component 6, embedded in the groove 101, forms a tight fit with the inner wall of the groove, constituting the first sealing interface. When the ladle 8 descends, the sealing component 6 contacts the bottom of the ladle 8 and compresses under pressure to achieve a seal, filling the microscopic gap between the bottom of the ladle 8 and the refractory components, forming a second sealing interface. This achieves a reliable double seal, effectively preventing external air intrusion and significantly reducing argon waste caused by leakage. The gas chamber 2 continuously sprays protective gas into the inner hole 9, forming a stable inert gas barrier within the inner hole 9, effectively isolating the molten steel from air. The synergistic effect of the double seal and the inert gas barrier effectively prevents the oxidation and burning of reactive elements such as chromium, molybdenum, vanadium, and niobium in the molten steel, avoiding oxide inclusions and surface wrinkling defects, thereby improving the mechanical properties and internal purity of the casting. Simultaneously, the device has a compact structure, eliminating the need for a large argon-filling chamber, significantly reducing equipment investment costs; the excellent sealing performance reduces argon consumption, lowering operating costs.

[0026] The gas protection device for casting steel parts provided by this invention has a compact structure and is easy to operate. It is specially designed for bottom-pouring process to ensure that the castings receive stable inert gas protection during the pouring process, thereby improving the surface quality and internal purity of the castings. It provides a reliable protection solution for the high-quality production of large, high-end cast steel parts.

[0027] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, in an optional embodiment of the present invention, the sealing component 6 is embedded in the groove 101, the radial dimension of the sealing component 6 is adapted to the radial dimension of the groove 101, the axial height of the sealing component 6 is greater than the depth of the groove 101, and the sealing component 6 is used to contact the bottom of the ladle 8 and compress and deform to achieve sealing during casting.

[0028] Specifically, the sealing component 6 is embedded in the groove 101 on the top end face of the refractory component 1, and its radial dimension is precisely matched with the radial dimension of the groove 101, so that the sealing component 6 can completely fill the annular space of the groove 101, ensuring that the installation is stable and does not loosen; the axial height of the sealing component 6 is greater than the depth of the groove 101, so that the upper surface of the sealing component 6 is higher than the top end face of the refractory component 1, so that when the ladle 8 descends, the bottom flange face of the ladle 8 contacts the sealing component 6 first, rather than directly colliding with the rigid refractory component; the sealing component 6 is made of a (relatively dense and capable) deformable material, which can be deformed under the pressure of the ladle 8 to achieve compression sealing, perfectly filling the microscopic gap between the bottom flange face of the ladle 8 and the groove 101, forming a reliable sealing interface, effectively preventing air from entering the protected area and preventing argon leakage.

[0029] In this optional embodiment, the radial dimension is precisely matched with the groove 101 to ensure that the sealing component 6 is securely embedded and will not shift or twist when the ladle 8 is lowered and pressed, thus ensuring the accuracy of the sealing position. By making the axial height greater than the depth of the groove 101, the upper surface of the sealing component 6 is higher than the top end face of the refractory component 1, ensuring that the bottom of the ladle 8 contacts the sealing component 6 first, avoiding direct collision between the hard refractory component and the ladle 8 and causing damage. Utilizing the compression deformation characteristics of the deformable sealing material, the microscopic unevenness of the contact surface is perfectly filled, achieving a 360° uniform seal without dead angles, effectively blocking air from entering the protected area and preventing argon leakage, thus ensuring the argon protection effect and reducing argon consumption. At the same time, the sealing component 6 partially recovers or cannot recover its original state after the ladle 8 is raised, which facilitates inspection after each use. If it cannot recover, it can be replaced, ensuring a long-lasting and reliable sealing effect for the next use, providing a key guarantee for the smooth pouring of molten steel in a pure argon atmosphere.

[0030] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, in an optional embodiment of the present invention, the sealing component 6 includes an annular asbestos ring, the outer diameter and inner diameter of which are adapted to the outer diameter and inner diameter of the groove 101, respectively, and the annular asbestos ring is embedded in the groove 101.

[0031] Specifically, during the casting process, the annular asbestos ring, acting as a deformable sealing material, is embedded within the groove 101 to form a fixed structure. Because the outer and inner diameters of the annular asbestos ring precisely match those of the groove 101, it completely fills the annular space of the groove 101 without shifting or loosening. When the ladle 8 descends, its bottom flange surface contacts the upper surface of the annular asbestos ring. Due to the compressible and deformable nature of the asbestos material, a seal is achieved, perfectly filling the microscopic unevenness of the contact surface and forming a reliable sealing interface.

[0032] In this optional embodiment, the annular asbestos ring is the core component of the sealing system. Its outer and inner diameters are precisely matched to the outer and inner diameters of the groove 101 on the top end face of the refractory component 1, allowing the asbestos ring to be accurately embedded within the groove 101 to form a stable structure. During the casting process, as the ladle 8 descends, its bottom flange surface contacts the upper surface of the asbestos ring. Due to the softness of the asbestos material, it can be compressed and deformed to achieve a seal, perfectly filling the microscopic unevenness of the contact surface and forming a reliable sealing interface. This effectively prevents air from intruding into the protected area and prevents argon leakage. This structure ensures that the asbestos ring will not shift or twist when the ladle 8 is pressed, and also facilitates inspection and replacement after each use (the annular asbestos ring is a consumable), ensuring the durability and reliability of the sealing effect. As shown in the figure Figure 3 As shown, in an optional embodiment of the present invention, the inner hole 9, the annular asbestos ring, and the pouring cup 7 are coaxially arranged.

[0033] Specifically, in the core structure and dimensional fit of the device, the refractory component 1 needs to have an inner hole, the diameter of which matches the size of the pouring cup; a continuous and regular annular groove 101 is designed on the top end face, the size of which is adapted to the inner and outer diameters of the asbestos ring for precise installation of the annular asbestos sealing ring. Based on this, the inner hole 9, the annular asbestos ring, and the pouring cup 7 in this invention are coaxially arranged, that is, they have a common central axis, forming a concentric fit structure.

[0034] Therefore, during the pouring process, the outlet of the ladle 8 is aligned with the upper end of the inner hole 9, and the lower end of the inner hole 9 is aligned with the pouring port of the pouring cup 7. The annular asbestos ring is embedded in the groove 101 on the top end face of the refractory component 1. The coaxial arrangement of the three ensures that after the molten steel flows out of the outlet of the ladle 8, it falls vertically into the inner hole 9, and then vertically into the pouring cup 7, forming a straight molten steel flow channel. This ensures that the entire molten metal flow channel from the ladle 8 to the sprue is in a straight and sealed state, guaranteeing the smooth flow of molten steel and the reliability of the seal. At the same time, the annular asbestos ring is coaxial with the inner hole 9 and the pouring cup 7, allowing the asbestos ring to evenly surround the outlet of the ladle 8. When the ladle 8 descends, the asbestos ring makes uniform contact with the bottom flange surface of the ladle 8, achieving a 360° uniform seal without dead angles through compression deformation, effectively preventing air intrusion and argon leakage.

[0035] like Figure 7 and Figure 8 As shown, in an optional embodiment of the present invention, the air chamber 2 is formed by bending a metal tube, the air chamber 2 is configured as an air collecting component 21, the air inlet is provided on the air collecting component 21 and connected to an external air source through an air inlet pipe 23, and there are multiple air outlets, each of which is provided with an air outlet pipe 22.

[0036] Specifically, the annular iron pipe gas chamber is made of Q275 steel pipe bent and welded, pre-embedded inside the refractory bricks to form a continuous, sealed cavity. One end has an argon inlet, and the other end has six evenly spaced circumferential outlets. Thus, the gas collecting component 21 has an annular structure and is pre-embedded inside the refractory component 1. The inlet is located on the gas collecting component 21 and connected to an external gas source (such as an argon cylinder) via an inlet pipe 23 to introduce protective gas. Multiple outlets are provided, such as... Figure 5 and Figure 6 The six air outlets shown are evenly distributed around the circumference. Each air outlet is provided with an air outlet pipe 22, which is positioned towards the inner hole 9 and is used to spray protective gas into the inner hole 9.

[0037] In this optional embodiment, the gas chamber 2 is embedded inside the refractory brick. This structure utilizes the heat insulation properties of the refractory brick to protect the gas chamber 2 from high temperatures, and also integrates the gas chamber 2 with the main body of the refractory brick, ensuring the compactness and stability of the device. The protective gas (argon) enters the gas collecting component 21 from an external gas source through the gas inlet pipe 23, flows circumferentially within the annular gas collecting component 21, and is evenly distributed before being ejected from each gas outlet pipe 22. The forming method of bending and welding the metal pipe ensures the sealing and structural strength of the gas chamber 2, enabling it to withstand a certain gas pressure without leakage. The annular structure design of the gas collecting component 21 allows the protective gas to be evenly distributed circumferentially, ensuring that the gas ejected from each gas outlet pipe 22 forms a barrier within the inner hole 9, isolating the molten steel from the air.

[0038] like Figure 7 and Figure 8 As shown, in an optional embodiment of the present invention, the gas collecting component 21 is arranged in a ring shape, the protective gas in the gas collecting component 21 flows in one direction, the plurality of gas outlets are evenly distributed along the circumference, and the gas flow direction at the connection between the gas collecting component 21 and the gas outlet pipe 22 is set at an obtuse angle to the gas outlet direction of the corresponding gas outlet pipe 22.

[0039] Specifically, the gas collecting component 21 is configured as a type of annular iron pipe (with a gap in the middle) (such as...). Figure 8As shown), and concentrically arranged with the inner hole 9; the gas collecting component 21 can be made of Q275 steel pipe bent and welded, pre-embedded inside the refractory brick to form a sealed cavity, with an argon inlet at one end and six gas outlets evenly opened circumferentially at the other end, the gas outlets adopting an anti-angle design. The gas collecting component 21 in this invention adopts an annular unidirectional gas path structure. After the protective gas enters the gas collecting component 21 from the inlet pipe 23, it flows in a single direction in the annular channel, rather than flowing in two directions. Multiple gas outlets (i.e., gas outlet pipes 22) are evenly distributed circumferentially along the gas collecting component 21. Figure 5 Six evenly distributed vents are shown to ensure that argon gas can be uniformly sprayed around the inner hole 9. The venting direction of the vent pipe 22 (made of Q275 material) is set at an obtuse angle to the gas flow direction (tangential direction) at this location within the gas collecting component 21 (the connection between the gas collecting component 21 and the vent pipe 22), that is, the angle between the venting direction and the tangent of the gas flow direction is greater than 90°, forming a reverse angle design, thereby limiting the layout angle of the vent pipe 22. Figure 7 As shown, the direction of each air outlet forms an angle b with the line connecting the inner end of the air outlet to the center of the circle, where b is 120°. The angle between the directions of two adjacent air outlets is c, where c is 60°.

[0040] During the casting process, argon gas first enters the gas collecting component 21 and flows unidirectionally along the ring, filling the entire annular gas cavity before being evenly distributed circumferentially. When the gas flows through each outlet, because the outlet direction is at an obtuse angle to the gas flow direction, the argon gas will not be preferentially ejected from the outlet closest to the inlet pipe 23 (made of Q275 material). Instead, it needs to completely fill the gas collecting component 21 first, and then be evenly ejected from the six outlets simultaneously (or, in other words, this design delays the ejection from the outlet pipe 22 near the inlet, avoiding affecting the ejection effect of the outlet pipe 22 far from the inlet). The ejected argon gas deviates from the center of the inner hole 9 and tilts to one side, forming a continuous annular gas curtain inside the inner hole 9, effectively isolating the molten steel column from any residual or infiltrated air.

[0041] In this optional embodiment, the outlet pipe 22 is designed with an obtuse angle opposite to the gas flow direction, which forces the argon gas to fill the entire gas collecting component 21 first before being evenly sprayed out from each outlet. This effectively avoids uneven airflow distribution caused by differences in gas resistance, ensuring that the gas output from each outlet is basically consistent, uniform, and diffusely sprayed into the protected area. The opposite angle design causes the sprayed argon gas to diffuse into the inner hole 9 area, forming a stable inert gas barrier that effectively isolates the molten steel from the air.

[0042] like Figure 7 As shown, in an optional embodiment of the present invention, the outlet end of the vent pipe 22 does not extend beyond the inner wall of the refractory component 1.

[0043] Specifically, the vent pipe 22 adopts a short pipe design, with its outlet end not exceeding the inner wall of the refractory component 1. That is, the end of the vent pipe 22 is located inside the refractory component 1 and does not extend into the space of the inner hole 9 (for example, the pipe opening is 50mm away from the inner wall). During the pouring process, molten steel with a temperature of up to 1500℃ or higher flows out from the outlet hole of the ladle 8, falls into the pouring cup 7 through the inner hole 9. If the vent pipe 22 is too long, its outlet end will extend into the inner hole 9, and will be directly exposed to the radiant heat of the high-temperature molten steel or even directly contact the molten steel column. This can easily cause the vent pipe 22 to oxidize, melt, or deform rapidly at high temperatures, causing blockage or damage to the gas path, affecting the argon protection effect, or even falling off and contaminating the molten steel. By designing the outlet end of the vent pipe 22 to not extend beyond the inner wall of the refractory component 1, the vent pipe 22 is wrapped in refractory material, with only the air jet (i.e. the air outlet of the air chamber 2) facing the inner hole 9. This effectively avoids direct contact between the vent pipe 22 and the high-temperature molten steel, ensuring that it remains in a relatively low-temperature protective environment during the casting process, thus ensuring the long-term stability and reliability of the gas circuit system.

[0044] In this optional embodiment, the short tube design allows the protective gas, such as argon, to quickly form a uniform gas curtain within the inner hole 9 after being ejected from the outlet pipe 22. This facilitates the rapid filling and continuous protection of the space within the inner hole 9 by argon. These effects collectively ensure the reliable operation and long service life of the argon protection device under extreme operating conditions.

[0045] As an optional embodiment of the present invention, the refractory component 1 is a refractory brick.

[0046] Specifically, white corundum refractory bricks are used as the core lining. Their key chemical composition and physical properties are shown in Table 1. The main components are alumina and silicon dioxide, possessing extremely high melting points and excellent high-temperature structural strength. They can directly withstand prolonged radiant heat and intense scouring from molten metal at temperatures up to 1500℃, ensuring the inner hole of the protective cover maintains its shape and size stability during operation, without softening, melting, or deformation. The refractory brick body must have an inner hole, the diameter of which matches the size of the pouring cup, ensuring precise pouring of molten steel and preventing splashing. Furthermore, a continuous and regular annular groove 101 is designed on the top end face of the refractory brick body. The dimensions of this groove 101 are adapted to the inner and outer diameters of the asbestos ring for precise insertion of the annular asbestos ring, a crucial structure for achieving a sealed fit with the bottom of the ladle 8.

[0047] Table 1. Indicators of Circular Heat-Resistant Bricks

[0048] A small amount of molten steel will splash onto the inner wall at high temperatures. The material chosen should not have any affinity with molten steel, so that even if a small amount of molten metal splashes, it can still flow down.

[0049] When in use, the inner hole 9 is directly circulated with high-temperature molten metal to ensure that the device is dry and to prevent cracking due to rapid heating. In order to ensure the durability of refractory bricks under rapid heating conditions, they must undergo strict step-by-step drying heat treatment before use to completely remove the moisture carried in the refractory bricks and prevent the lining from cracking or peeling off due to rapid vaporization of moisture during casting.

[0050] Besides serving as a core component in direct contact with molten metal at high temperatures, refractory bricks also provide excellent thermal insulation. Their inherent low thermal conductivity forms a highly efficient insulation layer, effectively preventing extreme internal temperatures from being conducted outwards. This prevents the external metal structure (such as the steel shell) from suffering strength reduction, oxidation, or even melting due to overheating, fundamentally ensuring the overall mechanical strength and long-term operational safety of the entire protective device.

[0051] Furthermore, the chemical stability of refractory bricks is indispensable for the metallurgical quality of castings. When refractory bricks, sintered at high temperatures, come into contact with molten CB2 steel, they exhibit extremely strong chemical inertness. This effectively resists the erosion of the molten metal and its slag, preventing contamination of the molten metal due to the corrosion of the refractory material itself, thus ensuring the high purity of the final casting.

[0052] like Figure 3 , Figure 9 and Figure 10 As shown, as an optional embodiment of the present invention, the gas protection device for casting steel parts further includes an outer protective shell 3 covering the outer surface of the refractory part 1, the outer protective shell 3 being provided with a lifting ring for hoisting, and the air inlet pipe 23 extending from inside the refractory part 1 to outside the outer protective shell 3.

[0053] Specifically, an outer protective shell 3 is provided to cover the outer surface of the refractory component 1. This outer protective shell 3 is made of 10mm thick annular sheet metal, which can be made of Q235 material. It covers the side of the refractory component 1 and extends partially to the bottom of the refractory component 1, avoiding the inner hole 9. It provides structural support for the internal refractory component 1 and can withstand various mechanical stresses generated during hoisting, transportation, installation, and use of the device, preventing the refractory component 1 from cracking, breaking, or loosening due to collision, compression, or vibration. Lifting rings are fixedly installed on the outer protective shell 3 to provide a reliable fulcrum for hoisting the device, facilitating the smooth hoisting of the device to the pouring position and precise placement by overhead cranes or other lifting equipment. At the same time, the air inlet pipe 23 extends from inside the refractory component 1 to outside the outer protective shell 3, so that the inlet of the air inlet pipe 23 is located outside the device, which facilitates connection to external air source pipelines. Operators can complete the connection and disassembly of quick connectors, such as threaded connections, without having to reach inside the device. One end of the inlet pipe 23 is connected to the gas collecting component 21 embedded in the refractory component 1, and the other end should have a switch or screw to facilitate quick insertion and removal of the argon blowing tube and ensure sealing. For example, a gas filling connector 5 is provided. The gas filling connector 5 is a quick connector. The quick connector is used to connect the argon cylinder's argon inlet pipe and the inlet pipe 23. The inlet pipe 23 is made of Q275 material.

[0054] Therefore, the outer protective shell 3 provides reliable mechanical protection for the refractory component 1, ensuring the overall stability and service life of the device under complex working conditions. At the same time, it plays a safety protection role, preventing operators from directly contacting the high-temperature refractory component and containing fragments in the event of accidental breakage of the refractory component 1, thus avoiding safety accidents and molten steel contamination. The lifting rings enable convenient hoisting and precise positioning of the device, making the handling of large protective devices safer and more efficient. The vent pipe 22 extends to the outside of the outer protective shell 3, allowing the connection and disassembly of the argon gas pipeline to be completed outside the device, making the operation more convenient and faster.

[0055] The following is a project example (this invention is based on a major coal project, project number: 2025ZD1701200).

[0056] Casting Information: Taking the production of CB2 stainless steel stepped components for ultra-high pressure inner cylinders as an example. The casting dimensions are approximately 1290mm × 400mm × 450mm, weighing 1.392t, and it features four steps with different wall thicknesses (120mm, 250mm, 350mm, 450mm). The material is CB2, requiring high purity and excellent mechanical properties.

[0057] Smelting and casting: Smelting is carried out in a medium-frequency induction furnace, and the tapping temperature is 1560℃. Casting is carried out using a bottom-drain ladle.

[0058] Protection device: The argon gas protection device described in this invention is customized, and its core dimensions are as follows: The inner hole 9 of refractory component 1 is φ300mm (matching the size of pouring cup 7). The dimensions of the groove 101 for the top annular seal are: outer diameter φ635mm, inner diameter φ460mm; The dimensions of the asbestos ring for the matching sealing component 6 are: outer diameter φ605mm, inner diameter φ490mm, and height 400mm. Argon gas outlets (outlets): 6, evenly distributed, 6-point pipes (inner diameter φ16mm, outer diameter φ20mm), with the direction at a 45° downward angle to the radial direction.

[0059] Comparison scheme: In the same smelting batch, another similar casting that was poured using a traditional simple argon gas protection device is used as a comparison, as shown in Table 2 below.

[0060] Table 2. Comparison of castings made using the device of the present invention and similar castings made using a traditional simple argon gas protection device.

[0061] This invention provides a casting method based on a gas protection device for casting steel parts as described in any of the preceding embodiments, comprising: The surface of the sprue 4 is smoothed, and the pouring cup 7 is placed on the sprue 4. The refractory component 1 is placed on the sprue 4, so that the lower end of the inner hole 9 of the refractory component 1 is aligned with the pouring port of the pouring cup 7. The sealing component 6 is embedded in the groove 101 of the refractory component 1. The ladle 8 is lifted so that the liquid outlet of the ladle 8 is aligned with the pouring cup 7. Specifically, in the pre-pouring preparation stage, the pouring platform is hollowed out during casting molding, with a level surface and compacted, stable sand. This ensures the protective device is placed stably to prevent molten steel from splashing. The lower end of the inner hole 9 of the refractory component 1 is aligned with the pouring port of the pouring cup 7 to ensure the molten steel falls precisely into the pouring cup 7, avoiding splashing and deviation. The sealing component 6 is embedded in the groove 101 to prepare for subsequent sealing. The ladle 8 is lifted and its outlet is aligned with the pouring cup 7 (e.g., the outlet is aligned with the center of the pouring cup 7) to ensure the molten steel falls accurately into the pouring cup 7 after flowing out. These preparatory works lay the foundation for subsequent argon gas protection and successful pouring.

[0062] Before pouring, protective gas is introduced through the air inlet of the air chamber 2 so that the protective gas flows through the air outlet of the air chamber 2 to the inner hole 9, thereby emptying the air in the inner hole 9, reducing the height of the ladle 8, and making the sealing component 6 surround the liquid outlet of the ladle 8 and contact the bottom of the ladle 8 so as to achieve sealing through compression deformation. Specifically, 3-5 minutes before pouring from the ladle 8, the argon supply valve is opened to introduce argon gas into the gas chamber 2 of the protective device. The initial flow rate is relatively large to quickly purge the air from the inner hole 9, and then adjusted to a suitable flow rate to ensure a smooth argon flow. After the flow is opened, the ladle 8 is lowered so that its bottom contacts the sealing component 6. This is to press the sealing component 6 tightly against the bottom of the ladle 8, forming a sealed space. The standard for good sealing is that the molten steel at the pouring gate is no longer visually bright, indicating that the air is isolated. This is a visual standard for judging the sealing effect. By first filling with gas, then purging the air, and then lowering the ladle to seal, a pure argon protective atmosphere is ensured to be formed inside the inner hole 9. With the protective gas continuously supplied, the molten steel in the ladle 8 is poured into the pouring cup 7 through the inner hole 9.

[0063] Specifically, during the entire casting process, argon gas is continuously and stably supplied. The argon gas fills the annular space between the molten metal column and the inner wall of the refractory component 1, forming an inert gas barrier that effectively isolates the molten metal from any residual or infiltrated air, thereby effectively preventing the oxidation of reactive elements such as aluminum, titanium, and chromium in the molten metal. The continuous introduction of protective gas ensures that the molten steel is always in a protective gas atmosphere during the entire casting process, effectively preventing the formation of oxide inclusions.

[0064] After pouring is complete, keep argon gas flowing for 2-3 minutes to protect the pouring tail and cool the inside of the device, thus protecting the entire pouring process.

[0065] The casting method provided by this invention first precisely aligns the lower end of the inner hole 9 of the refractory component 1 with the pouring port of the pouring cup 7 to ensure that the molten steel falls accurately into the pouring cup and prevents splashing. Before casting, protective gas is introduced to purge the air from the inner hole 9, and then the ladle 8 is lowered to press the sealing component 6 tightly against the bottom of the ladle 8, forming a sealed argon-protected space. Casting is carried out while the protective gas is continuously introduced, so that the molten steel is always surrounded by an inert gas barrier as it flows through the inner hole 9, effectively isolating it from the air. Through the synergistic cooperation of the above steps, the technical problem of easy oxidation of high alloy cast steel parts such as CB2 during the casting process is effectively solved, preventing the oxidation and burning loss of active elements such as chromium, molybdenum, vanadium, and niobium, significantly reducing surface wrinkling defects and internal oxide inclusions of the casting, and improving the mechanical properties and purity of the casting. At the same time, this method is simple to operate, has good compatibility with existing bottom-pouring ladle casting processes, does not require major modifications to the original equipment, reduces production costs, and improves the yield and quality stability of large high-end castings.

[0066] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

[0067] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A gas protection device for casting steel parts, characterized in that, include: Refractory component (1), the refractory component (1) has an inner hole (9) for molten steel to pass through, and a groove (101) is provided on its top end face. The refractory component (1) is used to be set on the pouring platform (4), and the lower end of the inner hole (9) is used to correspond to the pouring cup (7) on the pouring platform (4); sealing component (6), which is embedded in the groove (101) and is used to surround the liquid outlet of the ladle (8) and contact the bottom of the ladle (8) during pouring, so as to achieve sealing by compression deformation; gas chamber (2), which is provided in the refractory component (1), the gas chamber (2) is provided with an air inlet and an air outlet for introducing protective gas, the air outlet is set towards the inner hole (9) and is used to spray protective gas into the inner hole (9).

2. The gas protection device for casting steel parts according to claim 1, characterized in that, The sealing component (6) is embedded in the groove (101). The radial dimension of the sealing component (6) is adapted to the radial dimension of the groove (101). The axial height of the sealing component (6) is greater than the depth of the groove (101). The sealing component (6) is used to contact the bottom of the ladle (8) and compress and deform during casting to achieve sealing.

3. The gas protection device for casting steel parts according to claim 2, characterized in that, The sealing assembly (6) includes an annular asbestos ring, the outer diameter and inner diameter of which are adapted to the outer diameter and inner diameter of the groove (101), respectively, and the annular asbestos ring is embedded in the groove (101).

4. The gas protection device for casting steel parts according to claim 3, characterized in that, The inner hole (9), the annular asbestos ring, and the pouring cup (7) are arranged coaxially.

5. The gas protection device for casting steel parts according to any one of claims 1-4, characterized in that, The air chamber (2) is configured as an air collecting component (21), the air inlet is provided on the air collecting component (21) and connected to an external air source through an air inlet pipe (23), and there are multiple air outlets, each of which is provided with an air outlet pipe (22).

6. The gas protection device for casting steel parts according to claim 5, characterized in that, The gas collecting device (21) is arranged in a ring shape. The protective gas inside the gas collecting device (21) flows in one direction. The multiple gas outlets are evenly distributed along the circumference. The gas flow direction at the connection between the gas collecting device (21) and the gas outlet pipe (22) is set at an obtuse angle to the gas outlet direction of the corresponding gas outlet pipe (22).

7. The gas protection device for casting steel parts according to claim 5, characterized in that, The outlet end of the vent pipe (22) does not extend beyond the inner wall of the refractory component (1).

8. The gas protection device for casting steel parts according to claim 5, characterized in that, It also includes an outer protective shell (3) covering the outer surface of the refractory component (1), the outer protective shell (3) being provided with a lifting ring (4) for hoisting, and the air inlet pipe (23) extending from inside the refractory component (1) to outside the outer protective shell (3).

9. The gas protection device for casting steel parts according to any one of claims 1-4, characterized in that, The refractory component (1) is a refractory brick.

10. A casting method, characterized in that, The gas protection device for casting steel parts according to any one of claims 1-9 includes: The surface of the pouring platform (4) is flattened, and the pouring cup (7) is placed on the pouring platform (4). The refractory component (1) is placed on the pouring platform (4) so ​​that the lower end of the inner hole (9) of the refractory component (1) is aligned with the pouring port of the pouring cup (7). The sealing component (6) is embedded in the groove (101) of the refractory component (1). The ladle (8) is lifted so that the liquid outlet of the ladle (8) is aligned with the pouring cup (7). Before pouring, protective gas is introduced through the air inlet of the air chamber (2) so that the protective gas flows through the air outlet of the air chamber (2) to the inner hole (9), thereby emptying the air in the inner hole (9), reducing the height of the ladle (8), and making the sealing component (6) surround the liquid outlet of the ladle (8) and contact the bottom of the ladle (8) to achieve sealing through compression deformation; With the protective gas continuously supplied, the molten steel in the ladle (8) is poured into the pouring cup (7) through the inner hole (9).

Images