A medium frequency furnace smelting protection cover device

Abstract

A kind of intermediate frequency furnace smelting protective cover device, including high-temperature stainless steel protective cover, hanging bar, breather pipe, breather pipe connector and flow regulating valve, protective cover is matched with furnace mouth and is equipped with sealing structure, breather pipe extends to the place of 100-150mm above metal liquid surface, and protective atmosphere is formed by argon.The device adopts 310S stainless steel material, the breather pipe is double-layer heat insulation structure, and is equipped with digital flow valve to accurately control argon flow (5-15L / min).When using, the protective cover covers furnace mouth, and argon is introduced to reduce metal liquid oxidation.The utility model can effectively reduce the contact between metal liquid and air, reduce the generation of oxidized slag in metal liquid, control the chemical composition of metal liquid, improve the smelting quality of metal liquid, reduce casting surface and internal defects, and save production cost.

Description

Technical Field

[0001] This utility model relates to the technical field of casting production smelting processes, specifically a protective cover device for medium-frequency furnace smelting. By reducing the contact between molten metal and air, it optimizes the smelting environment, improves the quality of the molten metal, and is suitable for smelting scenarios in the casting industry that require high-purity molten metal. Background Technology

[0002] When molten metal (such as steel, iron, and aluminum alloys) is exposed to air, it undergoes an oxidation reaction with oxygen, producing oxide slag (such as FeO, Al2, and O3). Furthermore, the intrusion of nitrogen and water vapor can lead to defects such as porosity and inclusions. This not only affects the chemical stability of the molten metal but also reduces the mechanical properties (such as strength and toughness) and surface quality (such as porosity and inclusions) of the casting. This results in increased rework costs and time in subsequent stages, ultimately impacting product delivery.

[0003] Currently, the casting industry mainly uses the following methods to reduce the oxidation of molten metal, but all of them have certain limitations:

[0004] 1. During induction furnace smelting, a simple metal or refractory furnace cover is used to cover the furnace opening to reduce heat loss and allow some air to enter. However, this is not an effective way to isolate the air, and oxygen can still enter the furnace through gaps, leading to the oxidation of the molten metal. Furthermore, a protective atmosphere is not formed inside the furnace, making it impossible to suppress the formation of oxide slag.

[0005] 2. Spreading flux (such as borax, glass shards, etc.) on the surface of the molten metal forms a liquid coating to reduce oxidation. However, the flux may contaminate the molten metal and affect its chemical composition. Frequent additions are required, increasing operational complexity and cost. Furthermore, its effectiveness is limited for some highly reactive metals (such as magnesium alloys).

[0006] 3. Inert gases such as argon (Ar) or nitrogen (N2) are introduced into the furnace through vents on the side or top to create a protective atmosphere. However, the gas distribution is uneven, and some areas inside the furnace may still be exposed to air. Traditional ventilation methods (such as side blowing) may result in molten metal splashing or gas waste.

[0007] 4. Melting is carried out in a vacuum environment, completely avoiding oxidation problems. However, the equipment is expensive and only suitable for the production of high-end special alloys. Production efficiency is low, making it unsuitable for large-scale application in conventional foundry enterprises. Utility Model Content

[0008] To address the problems of easy oxidation of molten metal, unstable smelting quality, and high production costs in existing medium-frequency furnace smelting processes, this invention provides a simple, convenient, and efficient protective cover device for medium-frequency furnace smelting. This device optimizes the protective gas introduction method, reducing the contact between molten metal and air, thereby reducing the formation of oxide slag, stabilizing the chemical composition of the molten metal, improving casting quality, and simultaneously reducing subsequent rework costs.

[0009] The technical solution of this utility model is as follows:

[0010] A protective cover device for melting in a medium-frequency furnace, characterized in that it includes:

[0011] A protective cover (1) made of high-temperature resistant stainless steel is shaped to match the furnace opening of the medium-frequency furnace (7) and is used to cover the furnace opening to reduce air entry; the edge of the protective cover (1) is provided with an annular sealing structure to enhance the sealing with the furnace opening;

[0012] The lifting rod (2) is set on top of the protective cover (1) for lifting and moving the protective cover;

[0013] A vent pipe (3) is vertically fixed to the center of the protective cover (1), and its lower end extends to 100-150 mm above the surface of the molten metal (6) in the medium frequency furnace.

[0014] The vent pipe connector (4) connected to the upper end of the vent pipe (3) is used to quickly connect the gas supply pipe (9), which is connected to an argon cylinder (8). During the smelting process, argon gas is introduced from the gas supply pipe (9) to form an inert gas protective layer above the molten metal in the furnace.

[0015] The valve (5) installed on the gas delivery pipe (9) is used to regulate the argon gas flow rate.

[0016] Preferably, the annular sealing structure is a high-temperature resistant ceramic fiber sealing ring or a graphite sealing gasket.

[0017] Preferably, the high-temperature resistant stainless steel is 310S stainless steel or 253MA stainless steel, which can work for a long time in high-temperature environments above 1200℃.

[0018] Preferably, the vent pipe (3) adopts a double-layer sleeve structure, with the inner pipe conveying argon gas and the outer pipe forming a heat insulation layer between the inner and outer pipes.

[0019] Preferably, the flow regulating valve (5) is a digital flow control valve equipped with a flow display function.

[0020] Preferably, the inner surface of the protective cover (1) is provided with a high-temperature resistant reflective coating to reduce heat loss.

[0021] A medium-frequency furnace melting method, employing the aforementioned protective cover device, is characterized by comprising the following steps:

[0022] The protective cover (1) is hoisted to the furnace opening of the medium frequency furnace (7) using the hoisting rod (2) and placed stably;

[0023] Connect the gas supply pipe (9) to the gas inlet pipe connector (4), and open the valve (5) to introduce argon gas.

[0024] Adjust the flow rate to create a positive pressure of 10-15 Pa inside the furnace;

[0025] Argon gas is continuously introduced until the melting process is completed;

[0026] After the smelting is completed, close the valve (5), disconnect the gas supply pipe (9), and lift the protective cover (1).

[0027] Adjust the argon flow rate according to the type of liquid metal:

[0028] For molten steel, the argon flow rate is controlled at 8-12 L / min;

[0029] For aluminum alloys, the argon flow rate should be controlled at 5-8 L / min;

[0030] For copper alloys, the argon flow rate should be controlled at 10-15 L / min.

[0031] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0032] Argon gas is introduced into the medium-frequency furnace to fill the space above the molten metal with protective gas, thus solving the aforementioned problems.

[0033] A vent pipe is installed on the protective cover using high-temperature resistant stainless steel through welding. During melting in an induction furnace, the protective cover is placed on top to reduce contact between the molten metal and air, thus improving the quality of the castings.

[0034] The product has a clear structure. When performing medium-frequency furnace smelting operations, argon gas is introduced into the medium-frequency furnace through the protective cover, so that the space above the molten metal in the furnace is filled with protective gas. This can effectively reduce the contact between the molten metal and oxygen, reduce the generation of oxide slag in the molten metal, control the chemical composition of the molten metal, improve the quality of the molten metal, and save production costs. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the medium-frequency furnace melting protection cover device of this utility model.

[0036] In the diagram: 1 is the protective cover, 2 is the lifting rod, 3 is the vent pipe, 4 is the vent pipe connector, 5 is the valve, 6 is the molten metal, 7 is the medium frequency furnace, 8 is the argon cylinder, and 9 is the gas supply pipe. Detailed Implementation

[0037] To make the technical solution of this utility model clearer and more complete, and to facilitate understanding and implementation by those skilled in the art, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. The protective cover device described in this utility model is not limited to the following embodiments; any equivalent substitutions or improvements based on the concept of this utility model are within the protection scope of this utility model.

[0038] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of the medium-frequency furnace melting protective cover device of this utility model, as shown in the figure, including:

[0039] Protective Cover 1: In this embodiment, it is made of 310S high-temperature resistant stainless steel with a thickness of 8-12mm. Its shape perfectly matches the furnace opening of the medium-frequency furnace 7, ensuring a tight seal. The edge of Protective Cover 1 has an annular groove with an embedded high-temperature resistant ceramic fiber sealing ring (10mm thick) to enhance the seal with the furnace opening and prevent air ingress. The inner surface of Protective Cover 1 is coated with a high-temperature resistant reflective coating (such as an alumina coating) to reduce heat loss during the smelting process.

[0040] Lifting hook 2, welded to the top of protective cover 1, is made of the same 310S stainless steel as the protective cover and has a U-shaped structure for easy hooking by overhead cranes or lifting equipment. The welding points of lifting hook 2 are reinforced to ensure that it can still withstand the weight of the protective cover (approximately 50-100kg) in high-temperature environments.

[0041] Vent pipe 3 employs a double-layered structure. The inner pipe is made of 316L stainless steel (20mm in diameter) and is used to transport argon gas. The outer pipe is made of 310S stainless steel (30mm in diameter), forming a 5mm air insulation layer between the inner and outer pipes to reduce the impact of high temperatures on the argon gas temperature. The lower end of the vent pipe extends 120mm above the surface of the molten metal 6 (this can be adjusted to 100-150mm depending on smelting requirements) to ensure that argon gas evenly covers the surface of the molten metal.

[0042] Ventilation pipe connector 4 uses a quick-clamp type connector with a self-locking function, facilitating quick connection and disconnection of the air supply pipe 9. The connector is made of high-temperature resistant brass with a nickel-plated surface to improve corrosion resistance.

[0043] Valve 5 is a digital flow control valve equipped with an LCD display that shows the argon flow rate (in L / min) in real time. The flow rate adjustment range is 0-20 L / min, with an accuracy of ±0.5 L / min.

[0044] How to use the protective cover device of this utility model

[0045] (1) Install the protective cover

[0046] Before smelting, the protective cover device is hoisted to the top of the induction furnace opening by hooking the hoisting rod (2) with a crane or manual hoisting tool.

[0047] Slowly lower the protective cover so that the sealing ring at its edge fits tightly against the furnace opening, ensuring there are no noticeable gaps.

[0048] (2) Connect the argon gas supply system

[0049] Connect one end of the gas supply pipe (9) to the outlet of the argon cylinder (8), and quickly connect the other end to the gas inlet pipe connector (4).

[0050] Check the pipeline for leaks to ensure there are no gas leaks.

[0051] (3) Adjust the argon flow rate

[0052] Open the argon cylinder valve and set the initial pressure to 0.4-0.6 MPa.

[0053] Set the argon flow rate using the flow control valve:

[0054] Steel smelting: 8-12 L / min;

[0055] Aluminum alloy smelting: 5-8L / min;

[0056] Copper alloy smelting: 10-15L / min.

[0057] Monitor the traffic flow and ensure it remains stable.

[0058] (4) Monitoring of the smelting process

[0059] During the smelting process, argon gas is continuously introduced into the protective cover device to form an inert gas protective layer above the molten metal in the furnace.

[0060] Regularly check the condition of the sealing rings; replace them promptly if they show signs of aging or damage.

[0061] (5) Melting completion operation

[0062] Close the flow regulating valve (5) and the argon cylinder valve.

[0063] Disconnect the air supply pipe (9) from the air inlet pipe connector (4).

[0064] Lift the protective cover and clean any remaining metal splatter inside the vent pipe.

[0065] Experiments have shown that an argon protective layer can reduce the formation of oxide slag in molten metal by more than 60%. The oxygen content in molten steel can be controlled below 20 ppm. Heat loss is reduced by approximately 15%, lowering smelting energy consumption. The porosity of castings decreases by 50%, mechanical properties are improved, product delivery rates are increased, and production costs are saved.

Claims

1. A protective cover device for medium-frequency furnace melting, characterized in that, include: A protective cover (1) made of high-temperature resistant stainless steel is shaped to match the furnace opening of the medium-frequency furnace (7) and is used to cover the furnace opening to reduce air entry; the edge of the protective cover (1) is provided with an annular sealing structure to enhance the sealing with the furnace opening; The lifting rod (2) is set on top of the protective cover (1) for lifting and moving the protective cover; A vent pipe (3) is vertically fixed to the center of the protective cover (1), and its lower end extends to 100-150 mm above the surface of the molten metal (6) in the medium frequency furnace; The vent pipe connector (4) connected to the upper end of the vent pipe (3) is used to quickly connect the gas supply pipe (9), which is connected to an argon cylinder (8). During the smelting process, argon gas is introduced from the gas supply pipe (9) to form an inert gas protective layer above the molten metal in the furnace. The valve (5) installed on the gas delivery pipe (9) is used to regulate the argon gas flow rate.

2. The medium-frequency furnace melting protective cover device according to claim 1, characterized in that: The annular sealing structure is a high-temperature resistant ceramic fiber sealing ring or a graphite sealing gasket.

3. The medium-frequency furnace melting protective cover device according to claim 1, characterized in that, The high-temperature resistant stainless steel is 310S stainless steel or 253MA stainless steel, which can work for a long time in high-temperature environments above 1200℃.

4. The medium-frequency furnace melting protective cover device according to claim 1, characterized in that, The ventilation pipe (3) adopts a double-layer sleeve structure, with the inner pipe conveying argon gas and the outer pipe forming a heat insulation layer between the inner and outer pipes.

5. The medium-frequency furnace melting protective cover device according to claim 1, characterized in that, The valve (5) is a digital flow control valve equipped with a flow display function.

6. The medium-frequency furnace smelting protective cover device according to claim 1, characterized in that, The inner surface of the protective cover (1) is provided with a high-temperature resistant reflective coating to reduce heat loss.

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