A fixed core type hollow electroslag ingot production device and its use method

Abstract

The present invention relates to a fixed-core hollow electroslag ingot production device and its use method. The production device includes a bottom water tank, a crystallizer, a core rod, and a consumable electrode, as well as a sealing plate and a terminal. The crystallizer is a cylindrical structure and is arranged on the bottom water tank. The core rod is arranged in the middle of the bottom water tank. The consumable electrode is a tubular structure and is sleeved around the outer periphery of the core rod. The lower end of the consumable electrode is inserted into the liquid slag of the crystallizer. The top of the consumable electrode is sealed by a sealing plate. The sealing plate is provided with an air inlet and an exhaust hole, and is connected to an external power supply via a terminal. By controlling the atmosphere and pressure inside the hollow electrode, the burning of easily oxidized elements in the consumable electrode can be reduced during electroslag remelting and the liquid level can be ensured to be stable, thereby improving the quality of the hollow electroslag ingot, especially the cleanliness of the electroslag ingot.

Description

Technical Field

[0001] The present invention relates to the technical field of electroslag remelting, and in particular to a fixed-core hollow electroslag ingot production device and a use method thereof. Background Art

[0002] A large number of hollow tubular components are used in the aerospace, petrochemical, atomic energy and weapons industries. These components have particularly strict performance requirements on steel, and most of the steel used in these components is high-alloy special steel. Electroslag remelting is generally used in the production process.

[0003] Electroslag remelting (ESR) steel utilizes the resistance heat generated by passing an electric current through molten slag as a heat source for smelting. Existing ESR ingots are solid steel ingots that require forging, followed by boring and extrusion piercing to produce pipe fittings. Conventional boring and piercing methods, however, have low yield rates, complex production processes, and high costs. For certain specialized high-alloy steels, this method can also result in low yields and fail to meet high performance requirements.

[0004] Chinese patent application number 201710200071.X discloses a "device and method for producing small hollow electroslag ingots." The production device comprises an outer mold, an inner mold, a bottom water tank, a copper plate, and a circulating cooling system. Consumable electrodes undergo electroslag remelting between the inner and outer molds. The combined use of the inner and outer molds enables the production of hollow electroslag steel ingots. However, because this production device utilizes a combined inner and outer mold, the cooling requirements of the slag and metal pools are high. To maintain the high slag pool temperature and accelerate the heating and melting of the consumable electrodes, additional electroslag remelting power is required. Consequently, the power consumption per ton of steel is 1.5 to 2.0 times that of conventional electroslag remelting processes, increasing production costs. Furthermore, from the perspective of electroslag ingot cleanliness, since the inner and outer molds and the bottom water tank all dissipate heat from the ingot, this reduces the depth of the metal pool. This causes some fine inclusions to solidify within the ingot before they have time to float, thus reducing its cleanliness.

[0005] The book "Electroslag Remelting Metallurgy" edited by Xu Hongwu et al. describes a device for producing hollow electroslag ingots using a fixed non-metallic core rod. Analysis of the accompanying drawings shows that the non-metallic core rod in this device penetrates the bottom water tank. This core rod installation method can easily cause high-temperature slag or molten steel to leak along the side of the core rod into the bottom water tank, damaging the tank and, in severe cases, even leading to steel leakage accidents. Furthermore, the devices described in the two aforementioned documents also have significant shortcomings in terms of the structure and control of the consumable electrode. If the hollow cylindrical consumable electrode is not properly sealed during use, it is prone to air absorption, causing burnout of easily oxidized elements during the melting process. However, if it is completely sealed, the gas pressure inside the cylindrical consumable electrode will fluctuate continuously as the consumable electrode continues to melt and move downward, and under the influence of high temperatures. This will cause instability in the slag pool, reducing the surface quality of the electroslag ingot. Excessive fluctuations can even cause leakage of the molten steel pool, resulting in secondary oxidation of the molten steel.

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention develops a fixed-core hollow electroslag ingot production device, which can improve the quality of the hollow electroslag ingot, especially the cleanliness of the electroslag ingot. Summary of the Invention

[0007] The present invention provides a fixed-core hollow electroslag ingot production device and a method for using the same. By controlling the atmosphere and pressure inside the hollow electrode, the burning of easily oxidized elements in the consumable electrode during electroslag remelting can be reduced and the stability of the liquid level can be ensured, thereby improving the quality of the hollow electroslag ingot, especially the cleanliness of the electroslag ingot.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A fixed-core hollow electroslag ingot production device comprises a bottom water tank, a crystallizer, a core rod and a consumable electrode; further comprising a sealing plate and a terminal; the crystallizer is a cylindrical structure and is arranged on the bottom water tank; the core rod is arranged in the middle of the bottom water tank; the consumable electrode is a tubular structure and is sleeved on the periphery of the core rod, the lower end of the consumable electrode is inserted into the liquid slag of the crystallizer, the top of the consumable electrode is closed by a sealing plate, and an air inlet and an exhaust hole are provided on the sealing plate, which is connected to an external power supply via a terminal; the air inlet is connected to an inert gas source via a pipeline.

[0010] Furthermore, the inner cavity cross section of the consumable electrode is a regular shape or an irregular shape; the regular shape includes a circle and a polygon.

[0011] Furthermore, the inner cavity cross-section of the consumable electrode is circular and is coaxially arranged with the core rod. The inner cavity diameter of the consumable electrode is 300-600 mm, the distance between the inner surface of the consumable electrode and the outer surface of the core rod is 50-100 mm, and the wall thickness of the consumable electrode is 30-200 mm.

[0012] Furthermore, the material of the sealing plate is industrial pure iron, or the same material as the consumable electrode.

[0013] Furthermore, the core rod is a hollow structure and is made of a composite material; the outer layer is made of zirconium oxide, and the inner layer is made of corundum.

[0014] Furthermore, the thickness of the outer layer of the core rod is 0.5 to 2.0 cm, and the ratio of the core rod wall thickness to the inner hole diameter is 2:1 to 4:1.

[0015] Furthermore, a positioning and fixing groove is provided on the bottom water tank for fixing the core rod, and the depth of the positioning and fixing groove is 50 to 80 mm; the diameter of the positioning and fixing groove is 10 to 30 mm larger than the outer diameter of the core rod, and the height of the core rod is 30 to 50 mm larger than the height of the crystallizer.

[0016] Furthermore, the material of the crystallizer is copper, the inner diameter of the crystallizer is 400-800 mm, the height is 1000-3000 mm, and the wall thickness is 20-30 mm.

[0017] Furthermore, a spiral cooling water channel is opened along the height of the inner wall of the crystallizer. The diameter of the cooling water channel is 5 to 10 mm, and the height interval is 5 to 10 mm. The water inlet and outlet of the cooling water channel are respectively connected to the external cooling water circulation system.

[0018] A method for using a fixed core type hollow electroslag ingot production device comprises the following steps:

[0019] 1) Preheat the core rod by baking. The preheating includes low-temperature preheating stage, medium-temperature preheating stage and high-temperature preheating stage. The temperature of the low-temperature preheating stage is controlled at 500±10℃, the temperature of the medium-temperature preheating stage is controlled at 1000±20℃, and the temperature of the high-temperature preheating stage is controlled at 1600±20℃. The preheating time of each stage is not less than 2 hours;

[0020] 2) Insert the preheated core rod into the positioning and fixing groove, fill the gap between the core rod and the positioning and fixing groove with refractory mud, ensure that the core rod is stably in a vertical state, and install the crystallizer on the bottom water tank;

[0021] 3) Spread the electroslag material evenly on the upper surface of the bottom water tank, then lower the consumable electrode so that it enters the crystallizer and the bottom end contacts the electroslag material, and connect the terminal to the external power supply;

[0022] 4) Start the electroslag remelting operation, and the insertion depth of the consumable electrode in the liquid slag pool is always controlled at 50-100 mm; after the electroslag slag material is completely dissolved, input inert gas into the inner cavity of the consumable electrode through the air inlet hole, and control the inner cavity pressure of the consumable electrode at 0.11-0.14 MPa;

[0023] 5) When the remaining amount of the consumable electrode is 10% to 20% of its original weight, increase the flow rate of the inert gas so that the inert gas in the inner cavity of the consumable electrode overflows from the liquid slag, and at the same time control the insertion depth of the consumable electrode in the liquid slag pool to 20 to 50 mm;

[0024] 6) When the remaining amount of the consumable electrode is less than 5% of its original weight, stop the electroslag remelting operation, remove the remaining part of the consumable electrode from the crystallizer, wait for the electroslag ingot to completely solidify, leave it empty for 2 to 4 hours, then demould the crystallizer and lift out the electroslag ingot;

[0025] 7) Pass water into the core rod to crush and remove the core rod inside the electroslag ingot, completing the preparation of the hollow electroslag ingot.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) By controlling the atmosphere and pressure inside the hollow electrode, the quality of the hollow electroslag ingot, especially the cleanliness of the electroslag ingot, can be improved. The amount of oxygen added during the production process can be reduced from the original 10ppm to 5ppm, creating favorable conditions for the production of high value-added hollow electroslag ingots.

[0028] (2) The device has a simple structure and is easy to operate, which is beneficial for daily maintenance and can reduce maintenance costs;

[0029] (3) The electroslag atmosphere can be controlled during the production process, which is beneficial to reducing the burnout of easily oxidized elements during the melting process of the consumable electrode, and the burnout rate can be controlled below 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of a fixed core type hollow electroslag ingot production device according to the present invention (in use state, the electroslag slag materials in the crystallizer are solidified electroslag ingot 5, unsolidified molten metal 8 and liquid slag 4 from bottom to top).

[0031] Figure 2 is a cross-sectional view of the consumable electrode of the present invention.

[0032] Figure: 1. Air inlet 2. Sealing plate 3. Mandrel 4. Liquid slag 5. Electroslag ingot 6. Bottom water tank 7. Positioning and fixing groove 8. Molten metal 9. Crystallizer 10. Consumable electrode 11. Exhaust hole 12. Terminal DETAILED DESCRIPTION

[0033] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0034] like Figure 1As shown, the fixed core type hollow electroslag ingot production device of the present invention includes a bottom water tank 6, a crystallizer 9, a core rod 3 and a consumable electrode 10; it also includes a sealing plate 2 and a terminal 12; the crystallizer 9 is a cylindrical structure, which is arranged on the bottom water tank 6; the core rod 3 is provided in the middle of the bottom water tank 6; the consumable electrode 10 is a tubular structure, which is sleeved on the outer periphery of the core rod 3, and the lower end of the consumable electrode 10 is inserted into the liquid slag of the crystallizer 9, and the top of the consumable electrode 10 is closed by the sealing plate 2, and the sealing plate 2 is provided with an air inlet 1 and an exhaust hole 11, and is connected to an external power supply through a terminal 12; the air inlet 1 is connected to an inert gas source through a pipeline.

[0035] Furthermore, the inner cavity cross section of the consumable electrode 10 is a regular shape or an irregular shape; the regular shape includes a circle and a polygon.

[0036] Furthermore, the inner cavity cross section of the consumable electrode 10 is circular (eg Figure 2 As shown) and coaxially arranged with the core rod 3, the inner diameter of the consumable electrode 10 is 300-600 mm, the distance between the inner surface of the consumable electrode 10 and the outer surface of the core rod 3 is 50-100 mm, and the wall thickness of the consumable electrode 10 is 30-200 mm.

[0037] Furthermore, the sealing plate 2 is made of industrial pure iron, or the same material as the consumable electrode 10 .

[0038] Furthermore, the core rod 3 is a hollow structure and is made of a composite material; the outer layer is made of zirconium oxide, and the inner layer is made of corundum.

[0039] Furthermore, the thickness of the outer layer of the core rod 3 is 0.5 to 2.0 cm, and the ratio of the wall thickness of the core rod 3 to the inner hole diameter is 2:1 to 4:1.

[0040] Furthermore, a positioning and fixing groove 7 is provided on the bottom water tank 6 for fixing the core rod 3, and the depth of the positioning and fixing groove 7 is 50 to 80 mm; the diameter of the positioning and fixing groove 7 is 10 to 30 mm larger than the outer diameter of the core rod 3, and the height of the core rod 3 is 30 to 50 mm larger than the height of the crystallizer 9.

[0041] Furthermore, the material of the crystallizer 9 is copper, the inner diameter of the crystallizer 9 is 400-800 mm, the height is 1000-3000 mm, and the wall thickness is 20-30 mm.

[0042] Furthermore, a spiral cooling water channel is opened along the height of the inner wall of the crystallizer. The diameter of the cooling water channel is 5 to 10 mm, and the height interval is 5 to 10 mm. The water inlet and outlet of the cooling water channel are respectively connected to the external cooling water circulation system.

[0043] The method for using the fixed core type hollow electroslag ingot production device of the present invention comprises the following steps:

[0044] 1) Preheating the core rod 3, which includes a low-temperature preheating stage, a medium-temperature preheating stage, and a high-temperature preheating stage. The temperature of the low-temperature preheating stage is controlled at 500±10°C, the temperature of the medium-temperature preheating stage is controlled at 1000±20°C, and the temperature of the high-temperature preheating stage is controlled at 1600±20°C. The preheating time of each stage is not less than 2 hours;

[0045] 2) Insert the preheated core rod 3 into the positioning and fixing groove 7, fill the gap between the core rod 3 and the positioning and fixing groove 7 with refractory clay, ensure that the core rod 3 is stably in a vertical state, and install the crystallizer 9 on the bottom water tank 6;

[0046] 3) The electroslag slag is evenly spread on the upper surface of the bottom water tank 6, and then the consumable electrode 10 is lowered so that it enters the crystallizer 9 and the bottom end contacts the electroslag slag, and the terminal 12 is connected to the external power supply;

[0047] 4) Starting the electroslag remelting operation, the insertion depth of the consumable electrode 10 in the liquid slag pool is always controlled at 50-100 mm; after the electroslag slag material is completely dissolved, inert gas is input into the inner cavity of the consumable electrode 10 through the air inlet 1, and the inner cavity pressure of the consumable electrode 10 is controlled at 0.11-0.14 MPa;

[0048] 5) When the remaining amount of the consumable electrode 10 is 10% to 20% of its original weight, the flow rate of the inert gas is increased to allow the inert gas in the inner cavity of the consumable electrode 10 to overflow from the liquid slag 4, while the insertion depth of the consumable electrode 10 in the liquid slag pool is controlled to be 20 to 50 mm;

[0049] 6) When the remaining amount of the consumable electrode 10 is less than 5% of the original weight, the electroslag remelting operation is stopped, and the remaining part of the consumable electrode 10 is removed from the crystallizer 6. After the electroslag ingot 5 is completely solidified, it is left empty for 2 to 4 hours, and then the crystallizer 9 is demoulded and the electroslag ingot 5 is lifted out;

[0050] 7) Water is passed into the core rod 3 to crush and remove the core rod 3 inside the electroslag ingot 5, thereby completing the preparation of the hollow electroslag ingot.

[0051] In the fixed core type hollow electroslag ingot production device described in the present invention, the consumable electrode 10 adopts a hollow tubular structure, and the cross section of its inner cavity can be a regular shape such as a circle, a rectangle, or other regular or irregular shapes.

[0052] A sealing plate 2 made of the same material as the consumable electrode or industrial pure iron is welded to the bottom of the consumable electrode 10. A terminal 12 is welded to the center of the sealing plate 2. To prevent the easily oxidizable elements in the consumable electrode 10 from being oxidized by the air in the inner cavity during the electroslag remelting process, and to stabilize the pressure in the consumable electrode inner cavity, an air inlet 1 and an air outlet 11 are formed in the sealing plate 2. Inert gas is blown into the inner cavity of the consumable electrode through the air inlet 1. At the same time, some inert gas can be withdrawn through the air outlet 11 to maintain a stable pressure in the inner cavity.

[0053] The crystallizer 9 is arranged on the top of the bottom water tank 6. In order to facilitate the positioning and fixing of the core rod 3, a positioning and fixing groove 7 is opened at the center of the top of the bottom water tank 6, and the core rod 3 is inserted into the positioning and fixing groove 7.

[0054] The core rod 3 is hollow and made of a composite material. Its outer layer is zirconia, 0.5 to 2.0 cm thick, and its inner layer is corundum. The ratio of the core rod's wall thickness to its inner diameter is 2:1 to 4:1. The depth of the positioning and fixing groove 7 is 50 to 80 mm, and its inner diameter is 10 to 30 mm larger than the outer diameter of the core rod 3. The height of the core rod 3 is 30 to 50 mm greater than the height of the mold 9.

[0055] The inner diameter of the consumable electrode 10 is 300-600 mm, the inner surface is 50-100 mm away from the outer surface of the core rod 3, and the wall thickness of the consumable electrode 10 is 30-200 mm.

[0056] The mold 9 is made of copper plate and is cylindrical with an inner diameter of 400-800 mm and a height of 1000-3000 mm. The wall thickness of the mold 9 is 20-30 mm. Cooling water channels with a diameter of 5-10 mm are uniformly cut along the inner wall of the mold 9 at intervals of 5-10 mm along the height. These channels are connected to an external cooling water circulation system. During the electroslag remelting process, cooling water is introduced into the channels to cool the mold 9, flowing in from the bottom and out from the top.

[0057] The method for using the fixed core type hollow electroslag ingot production device of the present invention comprises the following steps:

[0058] Step 1: preheating the hollow core rod 3 by baking. To prevent thermal cracks from occurring during the preheating process of the core rod 3, the preheating process is divided into a low-temperature preheating stage, a medium-temperature preheating stage, and a high-temperature preheating stage. The temperature of the low-temperature preheating stage is controlled at 500±10°C, the temperature of the medium-temperature preheating stage is controlled at 1000±20°C, and the temperature of the high-temperature preheating stage is controlled at 1600±20°C. The preheating time of each stage is not less than 2 hours.

[0059] Step 2: Insert the preheated core rod 3 into the positioning and fixing groove 7, and fill the gap between the core rod 3 and the positioning and fixing groove 7 with refractory mud and compact it to keep the core rod in a vertical and stable state, and place the crystallizer 9 on the bottom water tank 6;

[0060] Step 3: Spread the electroslag material evenly on the top of the bottom water tank 6, then lower the consumable electrode into the crystallizer 9, and make the bottom end of the consumable electrode 10 contact the electroslag material, and connect the terminal 12 to the power supply.

[0061] Step 4: The electroslag remelting operation begins. The insertion depth of the consumable electrode 10 in the liquid slag pool is always controlled at 50-100 mm. After the electroslag slag material is completely dissolved, an inert gas (such as argon, or nitrogen when producing high-nitrogen steel) is introduced into the inner cavity of the consumable electrode 10 through the air inlet 1. The pressure in the cavity of the consumable electrode 10 is controlled at a slightly positive pressure of 0.11-0.14 MPa to prevent air from entering the inner cavity of the consumable electrode 10 during the electroslag remelting process, which may cause oxidation of easily oxidized elements.

[0062] Step 5: When the remaining weight of the consumable electrode 10 is 10% to 20% of its original weight, the upward movement of the molten metal pool inside the mold 9 can easily cause oxygenation in the electroslag ingot. At this time, the inert gas flow rate is increased to allow the inert gas in the consumable electrode 10 cavity to overflow from the liquid slag 4. To prevent excessive fluctuations in the liquid slag 4 caused by the inert gas overflow, the insertion depth of the consumable electrode 10 in the liquid slag pool is controlled to 20 to 50 mm.

[0063] Step 6: When the remaining amount of the consumable electrode 10 is less than 5% of the original weight, stop the electroslag remelting operation, remove the remaining part of the consumable electrode 10 from the crystallizer 9, wait for the electroslag ingot 5 to be completely solidified, and then leave it empty for 2 to 4 hours, then demold the crystallizer 9 and lift out the electroslag ingot 5.

[0064] Step seven: passing water into the core rod 3, and under the effect of thermal expansion and contraction, the core rod 3 inside the electroslag ingot 5 is broken and removed, thereby completing the preparation of the hollow electroslag ingot.

[0065] The following examples are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the protection scope of the present invention is not limited to the following examples.

[0066] [Example]

[0067] In this embodiment, the fixed core type hollow electroslag ingot production device is composed of a tubular consumable electrode 10, a core rod 3 made of refractory material, a crystallizer 9 and a bottom water tank 6.

[0068] The consumable electrode 10 has a circular inner cross-section with a diameter of 500 mm and a wall thickness of 50 mm. A sealing plate 2 made of industrial pure iron is welded to the top of the consumable electrode 10. The sealing plate 2 has an air inlet 1 and an exhaust hole 11. A terminal 12 is welded to the center of the sealing plate 2.

[0069] The core rod 3 has a height of 1545 mm and is made of a composite material. The outer layer is a zirconia layer with a thickness of 1 mm and the inner layer is a corundum layer. The outer diameter of the core rod 3 is 60 mm and a through hole with a diameter of 10 mm is opened inside the core rod.

[0070] The crystallizer 9 is made of copper plate and is a cylindrical structure with an inner diameter of 500 mm and a height of 1500 mm. The copper plate used to make the crystallizer 9 is 25 mm thick. Cooling water channels with a diameter of 8 mm are uniformly cut along the inner wall of the crystallizer 9 at 6 mm intervals along its height. These channels are connected to an external cooling water circulation system. The crystallizer 9 is mounted on a bottom water tank 6, which serves as a cooling mechanism. A positioning groove 7 with a depth of 60 mm and a diameter of 75 mm is located in the center of the bottom water tank 6 to accommodate the core rod 3.

[0071] In order to prepare a hollow electroslag ingot, the specific operation method of this embodiment is as follows:

[0072] Step 1: Preheat the core rod 3 by baking. To prevent thermal cracks from occurring during the preheating process, the preheating process is divided into a low-temperature preheating stage, a medium-temperature preheating stage, and a high-temperature preheating stage. The temperature of the low-temperature preheating stage is controlled at 500±10°C, the temperature of the medium-temperature preheating stage is controlled at 1000±20°C, and the temperature of the high-temperature preheating stage is controlled at 1600±20°C. The preheating time for each stage is 3 hours.

[0073] Step 2: Insert the preheated core rod 3 into the positioning and fixing groove 7, fill the gap between the two with refractory mud and compact it, so that the core rod 3 remains in a vertical and stable state, and place the crystallizer 9 on the bottom water tank 6;

[0074] Step 3: Spread the electroslag material evenly on the upper surface of the bottom water tank 6, then lower the consumable electrode 10 into the crystallizer 9, and make the bottom end of the consumable electrode 10 contact the electroslag material, and connect the terminal 12 to the power supply.

[0075] Step 4: Begin the electroslag remelting operation, controlling the insertion depth of the consumable electrode 10 into the liquid slag pool to 80 mm. After the electroslag slag material is completely dissolved, argon gas is introduced into the inner cavity of the consumable electrode 10 through the gas inlet 1. The pressure inside the consumable electrode 10 is controlled at a slightly positive pressure of 0.12 MPa to prevent air from entering the inner cavity of the consumable electrode 10 during the electroslag remelting process, which could cause oxidation of easily oxidized elements.

[0076] Step 5: When the remaining amount of the consumable electrode 10 is 15% of its original weight, the molten metal pool inside the crystallizer 9 will also move up to the upper part of the crystallizer 9, which may easily cause oxygenation of the electroslag ingot. At this time, the argon flow rate is increased to allow the argon gas in the inner cavity of the consumable electrode 10 to overflow from the liquid slag 4. In order to prevent the liquid slag 4 from fluctuating too much during the overflow of the inert gas, the insertion depth of the consumable electrode 10 in the liquid slag pool is controlled to 30 mm.

[0077] Step 6: When the remaining amount of the consumable electrode 10 is less than 5% of the original weight, stop the electroslag remelting operation, remove the remaining part of the consumable electrode 10 from the crystallizer 9, wait for the electroslag ingot 5 to completely solidify, and then leave it empty for 3 hours. Then, demold the crystallizer 6 and lift out the electroslag ingot 5.

[0078] Step seven: passing water into the core rod 3, and under the effect of thermal expansion and contraction, the core rod 3 inside the electroslag ingot 5 is broken and removed, thereby completing the preparation of the hollow electroslag ingot.

[0079] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for using a fixed core type hollow electroslag ingot production device, wherein the fixed core type hollow electroslag ingot production device comprises a bottom water tank, a crystallizer, a core rod and a consumable electrode; characterized in that: The crystallizer also includes a sealing plate and a terminal. The crystallizer is a cylindrical structure and is arranged on the bottom water tank. A core rod is arranged in the middle of the bottom water tank, and a positioning and fixing groove is provided on the bottom water tank for fixing the core rod. The consumable electrode is a tubular structure and is sleeved on the periphery of the core rod. The lower end of the consumable electrode is inserted into the liquid slag of the crystallizer. The top of the consumable electrode is closed by a sealing plate. The sealing plate is provided with an air inlet and an air outlet, and is connected to an external power supply through a terminal. The air inlet is connected to an inert gas source through a pipeline. The method for using the fixed core type hollow electroslag ingot production device comprises the following steps: 1) Preheat the core rod by baking. The preheating includes low-temperature preheating stage, medium-temperature preheating stage and high-temperature preheating stage. The temperature of the low-temperature preheating stage is controlled at 500±10℃, the temperature of the medium-temperature preheating stage is controlled at 1000±20℃, and the temperature of the high-temperature preheating stage is controlled at 1600±20℃. The preheating time of each stage is not less than 2 hours; 2) Insert the preheated core rod into the positioning and fixing groove, fill the gap between the core rod and the positioning and fixing groove with refractory mud, ensure that the core rod is stably in a vertical state, and install the crystallizer on the bottom water tank; 3) Spread the electroslag material evenly on the upper surface of the bottom water tank, then lower the consumable electrode so that it enters the crystallizer and the bottom end contacts the electroslag material, and connect the terminal to the external power supply; 4) Start the electroslag remelting operation, and the insertion depth of the consumable electrode in the liquid slag pool is always controlled at 50-100mm; after the electroslag slag material is completely dissolved, input inert gas into the inner cavity of the consumable electrode through the air inlet hole to control the inner cavity pressure of the consumable electrode at 0.11-0.14MPa; 5) When the remaining amount of the consumable electrode is 10% to 20% of its original weight, increase the flow rate of the inert gas so that the inert gas in the inner cavity of the consumable electrode overflows from the liquid slag. At the same time, control the insertion depth of the consumable electrode in the liquid slag pool to 20 to 50 mm; 6) When the remaining amount of the consumable electrode is less than 5% of its original weight, stop the electroslag remelting operation, remove the remaining part of the consumable electrode from the crystallizer, wait for the electroslag ingot to completely solidify, leave it empty for 2 to 4 hours, then demould the crystallizer and lift out the electroslag ingot; 7) Pass water into the core rod to crush and remove the core rod inside the electroslag ingot, completing the preparation of the hollow electroslag ingot.

2. The method for using a fixed core type hollow electroslag ingot production device according to claim 1, characterized in that: The inner cavity cross section of the consumable electrode is a regular shape or an irregular shape; the regular shape includes a circle and a polygon.

3. The method for using a fixed core type hollow electroslag ingot production device according to claim 2, characterized in that: The consumable electrode has a circular inner cavity cross section and is coaxially arranged with the core rod. The inner cavity diameter of the consumable electrode is 300-600 mm, the distance between the inner surface of the consumable electrode and the outer surface of the core rod is 50-100 mm, and the wall thickness of the consumable electrode is 30-200 mm.

4. The method for using a fixed core type hollow electroslag ingot production device according to claim 1, characterized in that: The material of the blocking plate is industrial pure iron, or the same material as the consumable electrode.

5. The method for using a fixed core type hollow electroslag ingot production device according to claim 1, characterized in that: The core rod is a hollow structure and is made of a composite material; the outer layer is made of zirconium oxide, and the inner layer is made of corundum.

6. The method for using a fixed core type hollow electroslag ingot production device according to claim 1, characterized in that: The thickness of the outer layer of the core rod is 0.5 to 2.0 cm, and the ratio of the core rod wall thickness to the inner hole diameter is 2:1 to 4:

1.

7. The method for using a fixed core type hollow electroslag ingot production device according to claim 1, characterized in that: The depth of the positioning and fixing groove is 50 to 80 mm; the diameter of the positioning and fixing groove is 10 to 30 mm larger than the outer diameter of the core rod, and the height of the core rod is 30 to 50 mm larger than the height of the crystallizer.

8. The method for using a fixed core type hollow electroslag ingot production device according to claim 1, characterized in that: The material of the crystallizer is copper, the inner diameter of the crystallizer is 400-800 mm, the height is 1000-3000 mm, and the wall thickness is 20-30 mm.

9. The method for using a fixed core type hollow electroslag ingot production device according to claim 1, characterized in that: The inner wall of the crystallizer is provided with a spiral cooling water channel along the height direction. The diameter of the cooling water channel is 5-10 mm and the height spacing is 5-10 mm. The water inlet and outlet of the cooling water channel are respectively connected to the external cooling water circulation system.

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