CN104439201B - A kind of large-scale steel ingot electroslag heat-sealing ejection device and method that is uniformly distributed thermal source - Google Patents

Abstract

A large-scale steel ingot electroslag heat sealing device and method for evenly distributing heat sources. The lower electrode cross arm and the double-layer graphite electrode pair; the inner graphite electrode of the double-layer graphite electrode pair is a solid column, and the outer graphite electrode is a hollow tube. In the slag; the upper electrode cross arm and the lower electrode cross arm are connected to the lifting arm and connected to the control cabinet; the inner graphite electrode is clamped by the upper holder, and the upper holder is connected to the upper electrode cross arm; The outer graphite electrode is clamped by the lower holder, and the lower holder is connected to the cross arm of the lower electrode. The invention improves the metal yield; improves the uniformity of the chemical composition of the steel ingot and the purity of the steel; improves the solidification condition of the center of the steel ingot; has high heating efficiency and good heating effect;

Description

A large-scale steel ingot electroslag heat sealing device and method with uniform heat source distribution

technical field

The invention belongs to the field of electroslag metallurgy and heavy equipment manufacturing, in particular to a large-scale steel ingot electroslag heat sealing device and method for evenly distributing heat sources.

Background technique

With the development of heavy equipment and nuclear power in China, the quality requirements for large steel ingots are getting higher and higher. In the process of preparing large steel ingots, there are problems such as loose shrinkage cavities, which are mainly caused by the insufficient insulation capacity of the riser and the smooth feeding of molten metal. The key to solving the above problems is to improve the insulation capacity of the riser, ensure the smoothness of the feeding channel, and improve the feeding capacity of the riser.

At present, there are already electric heating riser technologies in the industrial field, and these technologies heat and keep the riser through methods such as electric arc, plasma or induction heating. However, the above-mentioned device is relatively complicated and inconvenient to operate, and this problem becomes more prominent as the size of the steel ingot increases. In addition, the heat input in these devices is mainly concentrated near the heating body, the heating volume is small, the temperature distribution is uneven, and the heating efficiency is also low.

Electroslag heat capping is an electroslag metallurgy application technology that uses electroslag process to heat and keep the molten steel at the riser after casting the refined molten steel into the ingot mold or casting mold. This technology keeps the metal in the riser area in the liquid state during the solidification of the ingot or casting until the ingot or casting is solidified, so that the shrinkage of the metal during the solidification process can be continuously replenished by the liquid metal, eliminating the need for ingots or castings. The porosity and shrinkage defects in the center can significantly improve the quality of steel ingots and castings. The current electroslag thermal capping technology mostly uses single electrode heating. Chinese patent (CN100509214C) discloses an electroslag heating technology. This patent is aimed at large cast steel backup rolls, and is not suitable for large steel ingots. In addition, this patent uses single-electrode electroslag heating, which makes the current loop long and the heating efficiency is low. When the current passes through the large cast steel backup rolls, it will also generate Joule heat, which will adversely affect the original solidification process.

Contents of the invention

Aiming at the problems existing in the heat capping process of the large steel ingot solidification process at present, the present invention provides a large steel ingot electroslag heat capping device and method that evenly distributes heat sources.

Technical scheme of the present invention is:

An electroslag heat sealing device for large steel ingots that evenly distributes heat sources, including hydraulic fixed supports, hydraulic transmission rods, lifting arms, control cabinets and trolleys; hydraulic fixed supports and control cabinets are installed on the trolleys, and the lifting arms are inserted In the fixed support, the base of the hydraulic fixed support is connected to the hydraulic transmission rod, and the hydraulic transmission rod is connected to the control cabinet;

It also includes an upper holder, a lower holder, an upper electrode cross arm, a lower electrode cross arm and a pair of double-layer graphite electrodes.

The inner graphite electrode of the double-layer graphite electrode pair is a solid column, and the outer graphite electrode is a hollow tube. The two electrodes are coaxially aligned and inserted into the liquid pre-melted slag in the riser box.

The upper electrode cross arm and the lower electrode cross arm are connected to the lifting arm, and the upper electrode cross arm and the lower electrode cross arm are connected to the control cabinet.

The graphite electrode in the inner layer is held by an upper holder, and the upper holder is connected to the cross arm of the upper electrode.

The outer graphite electrode is clamped by a lower holder, and the lower holder is connected to the lower electrode cross arm.

There are high temperature resistant insulating gaskets between the upper electrode cross arm and the lifting arm, and between the lower electrode cross arm and the lifting arm.

The ratio of the cross-sectional area of the inner layer graphite electrode to the cross-sectional area of the upper surface of the riser box is 0.3-0.4.

The cross-sectional area of the graphite electrode in the inner layer is equal to the cross-sectional area of the graphite electrode in the outer layer.

The difference between the radius of the inner layer graphite electrode and the inner radius of the outer layer graphite electrode is 10%-20% of the radius of the inner layer graphite electrode.

The insertion depth of the inner graphite electrode in the liquid pre-slag is the same as the insertion depth of the outer graphite electrode in the liquid pre-slag, which is 20 mm to 50 mm.

The method for performing electroslag heat sealing of large steel ingots using the large steel ingot electroslag heat sealing device with evenly distributed heat sources includes the following steps:

Step 1: Determine the composition and slag thickness of the quaternary pre-melted slag according to the solidification process of the steel ingot, and use the slag melting furnace to melt the slag;

Step 2: According to the diameter of the upper surface of the riser box and the ratio of the cross-sectional area of the inner graphite electrode to the cross-sectional area of the upper surface of the riser box, determine the radius of the inner graphite electrode and the size of the heating current;

Step 3: According to the radius of the inner graphite electrode and the difference between the inner radius of the inner graphite electrode and the inner radius of the outer graphite electrode, and according to the principle that the cross-sectional area of the inner graphite electrode is equal to the cross-sectional area of the outer graphite electrode, determine the diameter of the outer graphite electrode inner and outer radii;

Step 4: After the molten steel is poured, pour the liquid pre-slag into the riser box;

Step 5: Move the trolley to the side of the mold, turn on the power of the control cabinet, adjust the height of the lifting arm, insert the inner graphite electrode and the outer graphite electrode into the liquid pre-melted slag to a certain depth, and adjust the heating current;

Step 6: The heating current enters the upper electrode cross arm through the cable, flows into the inner graphite electrode through the upper holder, then passes through the liquid pre-melted slag, flows out from the outer graphite electrode, enters the lower electrode cross arm and passes through the lower holder, Finally, it flows back to the cable to form a loop;

Step 7: After the steel ingot is solidified, raise the lifting arm, pull out the inner graphite electrode and the outer graphite electrode, and turn off the power of the control cabinet;

Step 8: The electroslag heat sealing of the steel ingot is completed, and the lifting and demoulding of the steel ingot are carried out.

The composition of the quaternary pre-melted slag is CaF ₂ , Al ₂ O ₃ , CaO and MgO, and by weight, CaF ₂ accounts for 25-35%, Al ₂ O ₃ accounts for 30-45%, and CaO accounts for 10-20% , MgO accounts for 10~20%.

The slag thickness of the liquid pre-melted slag is 100-200mm.

The electroslag heating uses single-phase alternating current, the power frequency is 50Hz, and the heating current is determined according to the size of the riser box. When the diameter of the upper end surface of the riser box is less than 1800mm, the current is 2000A; when the diameter of the upper end surface of the riser box is 1801~ When the diameter of the upper surface of the riser box is 2301mm, the current is 2500A; when the diameter of the upper surface of the riser box is 2301~3000mm, the current is 3000A; when the diameter of the upper surface of the riser box is greater than 3000mm, the current is 4000A.

Beneficial effect:

(1) Save metal and increase metal yield. Since the shrinkage of the steel ingot or casting is continuously replenished during the solidification process, the center porosity and shrinkage cavity defects are eliminated, and the scrap rate is reduced. At the same time, since the final solidification of the riser is guaranteed, the volume of the riser can be reduced, and the metal consumption is reduced. For example, casting a 9t heavy turbine blade, the use of electroslag thermal capping technology can increase the metal utilization rate of the riser by 25%.

(2) Improve the uniformity of the chemical composition of the steel ingot and the purity of the steel. Due to the presence of a heat source on the top of the ingot, the phenomenon of "crystallization rain" that occurs during the solidification of ordinary ingots is avoided, and the negative segregation cone at the lower part of the ingot is eliminated. At the same time, the non-metallic inclusions enriched in the center of the steel ingot contact with the high-temperature slag pool at the top of the steel ingot along with the liquid metal flow, and react into the slag pool, thereby reducing the non-metallic inclusions in the steel ingot.

(3) The solidification condition of the steel ingot center is improved. Because there is a high-temperature heat source on the top of the ingot, and the metal droplets of the melting electrode also transfer heat to the liquid in the ingot from top to bottom, which changes the thermal state of the ingot during solidification and enables the directional solidification of the ingot from bottom to top. In addition, the change of thermal state also affects the crystallization speed of the metal and the temperature gradient of the solidification front, which makes the grain size smaller and the solidification structure denser than that of ordinary steel ingots. By changing the process parameters of electroslag thermal capping and controlling the input power to the steel ingot, the crystallization form of the metal can be changed to obtain the desired solidification structure.

(4) High heating efficiency and good heating effect. Electroslag heating belongs to resistance heating, most of the heat is transferred to molten steel through liquid pre-melted slag, the heat loss is less, and the thermal efficiency can reach more than 90%. Moreover, the inner column and outer tube coaxial bipolar series electrodes are used to make the slag temperature distribution more accurate. Uniform, the current flows in from the inner columnar graphite electrode, passes through the liquid pre-melted slag, and flows out from the outer tubular graphite electrode. The slag temperature distribution is more uniform and the heating effect is good.

(5) Improve the utilization rate of riser molten steel. After heating with electroslag, the thermal insulation capacity of the riser is improved. Therefore, during the solidification process, the feeding channel remains unobstructed, which improves the solidification conditions of the steel ingot and the quality of the steel ingot. The utilization rate of the riser liquid steel can be increased by more than 20%. the metal yield.

(6) Improve the utilization rate of steel ingots. After the steel ingot is poured, electroslag heating can quickly establish a positive temperature gradient, which can effectively suppress the possibility of segregation, especially the negative segregation at the lower part of the steel ingot, so that the removal of the tail of the steel ingot is reduced and the utilization rate of the steel ingot is improved.

(7) It adopts bipolar series connection, self-contained circuit, simple equipment structure and easy operation. The circuit, temperature measurement and control equipment of the electroslag heat sealing device of the present invention are all integrated on the trolley, which is convenient for transportation and simple operation, and is suitable for heating risers of steel ingots of different weights.

Description of drawings

Fig. 1 is a schematic diagram of a large-scale steel ingot electroslag thermal capping device with evenly distributed heat sources according to an embodiment of the present invention, wherein, 1-inner layer graphite electrode; 2-upper holder; 3-lower holder; 4-outer layer graphite electrode; 5-riser box; 6-mold; 7-base; 8-upper electrode cross arm; 9-lower electrode cross arm; 10-high temperature resistant insulating gasket; 11-lifting arm; 12-hydraulic fixed support; Hydraulic transmission rod; 14-cable; 15-control cabinet; 16-car.

detailed description

The specific implementation of the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Example 1

A large-scale electroslag heat sealing device for uniformly distributing heat sources, as shown in Fig. The cabinets 15 are installed on the trolley 16, the lifting arm 11 is inserted into the hydraulic fixed support 12, the hydraulic fixed support base 12 is connected to the hydraulic transmission rod 13, and the hydraulic transmission rod 13 is connected to the control cabinet 15;

It also includes an upper holder 2, a lower holder 3, an upper electrode cross arm 8, a lower electrode cross arm 9 and a double-layer graphite electrode pair;

The inner graphite electrode 1 of the double-layer graphite electrode pair is a solid column, and the outer graphite electrode 4 is a hollow tube. The two electrodes are coaxially aligned and inserted into the liquid pre-slag in the riser box 5; the riser box 5 is located at Above the mold 6, the mold 6 is installed on the base 7.

The upper electrode cross arm 8 and the lower electrode cross arm 9 are connected to the lifting arm 11, and the upper electrode cross arm 8 and the lower electrode cross arm 9 are connected to the control cabinet 15 through the cable 14;

The inner graphite electrode 1 is clamped by the upper holder 2, and the upper holder 2 is connected to the upper electrode cross arm 8;

The outer layer graphite electrode 4 is clamped by the lower holder 3 , and the lower holder 3 is connected to the lower electrode cross arm 9 .

Between the upper electrode cross arm 8 and the lifting arm 11 , and between the lower electrode cross arm 9 and the lifting arm 11 , there are high temperature resistant insulating gaskets 10 .

The ratio of the cross-sectional area of the inner layer graphite electrode 1 to the cross-sectional area of the upper surface of the riser box 5 is 0.3-0.4.

The cross-sectional area of the inner graphite electrode 1 is equal to the cross-sectional area of the outer graphite electrode 4 .

The difference between the radius of the inner graphite electrode 1 and the inner radius of the outer graphite electrode 4 is 10%-20% of the radius of the inner graphite electrode 1 .

The insertion depth of the inner layer graphite electrode 1 in the liquid pre-slag is the same as the insertion depth of the outer layer graphite electrode 4 in the liquid pre-slag, which is 20 mm to 50 mm.

In this embodiment, a large steel ingot of 140 tons is produced, the material is 0Cr13Ni4Mo stainless steel, the filling time is 26 minutes, and the pouring temperature is 1550° C. The weight of the steel ingot riser box is 14 tons, the diameter of the upper end surface of the riser box is 1400mm, the diameter of the lower end surface is 1550mm, and the height of the riser box is 400mm.

A method for performing electroslag heat sealing of a large steel ingot by using a large steel ingot electroslag heat sealing device with evenly distributed heat sources includes the following steps:

Step 1: Determine the composition and slag thickness of the quaternary pre-melted slag according to the solidification process of the steel ingot, and use the slag melting furnace to melt the slag;

By weight, the composition of the pre-melted slag is 31% CaF ₂ , 40% Al ₂ O ₃ , 16% CaO, 13% MgO, and a slag thickness of 130mm;

Step 2: According to the diameter of the upper surface of the riser box and the ratio of the cross-sectional area of the inner graphite electrode to the cross-sectional area of the upper surface of the riser box of 0.3, determine the radius of the inner graphite electrode to be 383mm and the heating current to be 2000A;

Step 3: According to the radius of the inner graphite electrode and the difference between the radius of the inner graphite electrode and the inner radius of the outer graphite electrode, which is 10% of the radius of the inner graphite electrode, it is 38.3mm, and the inner radius of the outer graphite electrode is 421.3mm, according to The principle that the cross-sectional area of the inner graphite electrode is equal to the cross-sectional area of the outer graphite electrode determines that the inner and outer radius of the outer graphite electrode is about 569mm;

Step 4: After the molten steel is poured, pour the liquid pre-slag into the riser box;

Step 5: Move the trolley to the side of the mold, turn on the power of the control cabinet, adjust the height of the lifting arm, insert the inner graphite electrode and the outer graphite electrode into the liquid pre-slag to a depth of 25mm, and adjust the heating current to 2000A;

Step 6: The heating current enters the upper electrode cross arm through the cable, flows into the inner graphite electrode through the upper holder, then passes through the liquid pre-melted slag, flows out from the outer graphite electrode, enters the lower electrode cross arm and passes through the lower holder, Finally, it flows back to the cable to form a loop;

Step 7: After the steel ingot is solidified, raise the lifting arm, pull out the inner graphite electrode and the outer graphite electrode, and turn off the power of the control cabinet;

Step 8: The electroslag heat sealing of the steel ingot is completed, and the lifting and demoulding of the steel ingot are carried out.

Example 2

A large-scale electroslag heat sealing device for uniformly distributing heat sources, as shown in Fig. The cabinets 15 are installed on the trolley 16, the lifting arm 11 is inserted into the hydraulic fixed support 12, the hydraulic fixed support base 12 is connected to the hydraulic transmission rod 13, and the hydraulic transmission rod 13 is connected to the control cabinet 15;

It also includes an upper holder 2, a lower holder 3, an upper electrode cross arm 8, a lower electrode cross arm 9 and a double-layer graphite electrode pair;

The inner graphite electrode 1 of the double-layer graphite electrode pair is a solid column, and the outer graphite electrode 4 is a hollow tube. The two electrodes are coaxially aligned and inserted into the liquid pre-slag in the riser box 5; the riser box 5 is located at Above the mold 6, the mold 6 is installed on the base 7.

The upper electrode cross arm 8 and the lower electrode cross arm 9 are connected to the lifting arm 11, and the upper electrode cross arm 8 and the lower electrode cross arm 9 are connected to the control cabinet 15 through the cable 14;

The inner graphite electrode 1 is clamped by the upper holder 2, and the upper holder 2 is connected to the upper electrode cross arm 8;

The outer layer graphite electrode 4 is clamped by the lower holder 3 , and the lower holder 3 is connected to the lower electrode cross arm 9 .

Between the upper electrode cross arm 8 and the lifting arm 11 , and between the lower electrode cross arm 9 and the lifting arm 11 , there are high temperature resistant insulating gaskets 10 .

The ratio of the cross-sectional area of the inner layer graphite electrode 1 to the cross-sectional area of the upper surface of the riser box 5 is 0.3-0.4.

The cross-sectional area of the inner graphite electrode 1 is equal to the cross-sectional area of the outer graphite electrode 4 .

The difference between the radius of the inner graphite electrode 1 and the inner radius of the outer graphite electrode 4 is 10%-20% of the radius of the inner graphite electrode 1 .

The insertion depth of the inner layer graphite electrode 1 in the liquid pre-slag is the same as the insertion depth of the outer layer graphite electrode 4 in the liquid pre-slag, which is 20 mm to 50 mm.

In this embodiment, a large steel ingot of 200 tons is produced, the material is 42CrMo, the filling time is 40 minutes, and the pouring temperature is 1560°C. The weight of the steel ingot riser box is 18 tons, the diameter of the upper end surface of the riser box is 1900mm, the diameter of the lower end surface is 2100mm, and the height of the riser box is 600mm.

A method for performing electroslag heat sealing of a large steel ingot by using a large steel ingot electroslag heat sealing device with evenly distributed heat sources includes the following steps:

Step 1: Determine the composition and slag thickness of the quaternary pre-melted slag according to the solidification process of the steel ingot, and use the slag melting furnace to melt the slag;

By weight, the composition of pre-melted slag is 31% CaF ₂ , 40% Al ₂ O ₃ , 16% CaO, 13% MgO, and the slag thickness is 142mm;

Step 2: According to the diameter of the upper surface of the riser box and the ratio of the cross-sectional area of the inner graphite electrode to the cross-sectional area of the upper surface of the riser box of 0.35, determine the radius of the inner graphite electrode to be 562mm and the heating current to be 2500A;

Step 3: According to the radius of the inner graphite electrode and the difference between the radius of the inner graphite electrode and the inner radius of the outer graphite electrode, that is, 15% of the radius of the inner graphite electrode, it is 84.3mm, and the inner radius of the outer graphite electrode is 646.3mm, according to The principle that the cross-sectional area of the inner graphite electrode is equal to the cross-sectional area of the outer graphite electrode determines that the inner and outer radius of the outer graphite electrode is about 856mm;

Step 4: After the molten steel is poured, pour the liquid pre-slag into the riser box;

Step 5: Move the trolley to the side of the mold, turn on the power of the control cabinet, adjust the height of the lifting arm, insert the inner graphite electrode and the outer graphite electrode into the liquid pre-melted slag to a depth of 35mm, and adjust the heating current to 2500A;

Step 6: The heating current enters the upper electrode cross arm through the cable, flows into the inner graphite electrode through the upper holder, then passes through the liquid pre-melted slag, flows out from the outer graphite electrode, enters the lower electrode cross arm and passes through the lower holder, Finally, it flows back to the cable to form a loop;

Step 7: After the steel ingot is solidified, raise the lifting arm, pull out the inner graphite electrode and the outer graphite electrode, and turn off the power of the control cabinet;

Step 8: The electroslag heat sealing of the steel ingot is completed, and the lifting and demoulding of the steel ingot are carried out.

Example 3

A large-scale electroslag heat sealing device for uniformly distributing heat sources, as shown in Fig. The cabinets 15 are installed on the trolley 16, the lifting arm 11 is inserted into the hydraulic fixed support 12, the hydraulic fixed support base 12 is connected to the hydraulic transmission rod 13, and the hydraulic transmission rod 13 is connected to the control cabinet 15;

It also includes an upper holder 2, a lower holder 3, an upper electrode cross arm 8, a lower electrode cross arm 9 and a double-layer graphite electrode pair;

The inner graphite electrode 1 of the double-layer graphite electrode pair is a solid column, and the outer graphite electrode 4 is a hollow tube. The two electrodes are coaxially aligned and inserted into the liquid pre-slag in the riser box 5; the riser box 5 is located at Above the mold 6, the mold 6 is installed on the base 7.

The upper electrode cross arm 8 and the lower electrode cross arm 9 are connected to the lifting arm 11, and the upper electrode cross arm 8 and the lower electrode cross arm 9 are connected to the control cabinet 15 through the cable 14;

The inner graphite electrode 1 is clamped by the upper holder 2, and the upper holder 2 is connected to the upper electrode cross arm 8;

The outer layer graphite electrode 4 is clamped by the lower holder 3 , and the lower holder 3 is connected to the lower electrode cross arm 9 .

Between the upper electrode cross arm 8 and the lifting arm 11 , and between the lower electrode cross arm 9 and the lifting arm 11 , there are high temperature resistant insulating gaskets 10 .

The ratio of the cross-sectional area of the inner layer graphite electrode 1 to the cross-sectional area of the upper surface of the riser box 5 is 0.3-0.4.

The cross-sectional area of the inner graphite electrode 1 is equal to the cross-sectional area of the outer graphite electrode 4 .

The difference between the radius of the inner graphite electrode 1 and the inner radius of the outer graphite electrode 4 is 10%-20% of the radius of the inner graphite electrode 1 .

The insertion depth of the inner layer graphite electrode 1 in the liquid pre-slag is the same as the insertion depth of the outer layer graphite electrode 4 in the liquid pre-slag, which is 20 mm to 50 mm.

In this embodiment, a large steel ingot of 220 tons is produced, the material is 42CrMo, the filling time is 50 minutes, and the pouring temperature is 1560°C. The weight of the steel ingot riser is 24 tons, the diameter of the upper surface of the riser is 2500mm, the diameter of the lower surface is 2700mm, and the height of the riser is 800mm. A method for performing electroslag heat sealing of a large steel ingot by using a large steel ingot electroslag heat sealing device with evenly distributed heat sources includes the following steps:

Step 1: Determine the composition and slag thickness of the quaternary pre-melted slag according to the solidification process of the steel ingot, and use the slag melting furnace to melt the slag;

By weight, the composition of pre-melted slag is CaF ₂ accounting for 26%, Al ₂ O ₃ accounting for 45%, CaO accounting for 14%, MgO accounting for 15%, and the slag thickness is 160mm;

Step 2: According to the diameter of the upper surface of the riser box and the ratio of the cross-sectional area of the inner layer graphite electrode to the upper end surface of the riser box of 0.35, determine the radius of the inner layer graphite electrode to be 739mm and the heating current to be 3000A;

Step 3: According to the radius of the inner graphite electrode and the difference between the radius of the inner graphite electrode and the inner radius of the outer graphite electrode, that is, 15% of the radius of the inner graphite electrode, it is 110.85mm, and the inner radius of the outer graphite electrode is 849.85mm, according to The principle that the cross-sectional area of the inner graphite electrode is equal to the cross-sectional area of the outer graphite electrode determines that the inner and outer radius of the outer graphite electrode is about 1126mm;

Step 4: After the molten steel is poured, pour the liquid pre-slag into the riser box;

Step 5: Move the trolley to the side of the mold, turn on the power supply of the control cabinet, adjust the height of the lifting arm, insert the inner graphite electrode and the outer graphite electrode into the liquid pre-melted slag to a depth of 40mm, and adjust the heating current to 3000A;

Step 6: The heating current enters the upper electrode cross arm through the cable, flows into the inner graphite electrode through the upper holder, then passes through the liquid pre-melted slag, flows out from the outer graphite electrode, enters the lower electrode cross arm and passes through the lower holder, Finally, it flows back to the cable to form a loop;

Step 7: After the steel ingot is solidified, raise the lifting arm, pull out the inner graphite electrode and the outer graphite electrode, and turn off the power of the control cabinet;

Step 8: The electroslag heat sealing of the steel ingot is completed, and the lifting and demoulding of the steel ingot are carried out.

Example 4

A large-scale electroslag heat sealing device for uniformly distributing heat sources, as shown in Fig. The cabinets 15 are installed on the trolley 16, the lifting arm 11 is inserted into the hydraulic fixed support 12, the hydraulic fixed support base 12 is connected to the hydraulic transmission rod 13, and the hydraulic transmission rod 13 is connected to the control cabinet 15;

It also includes an upper holder 2, a lower holder 3, an upper electrode cross arm 8, a lower electrode cross arm 9 and a double-layer graphite electrode pair;

The inner graphite electrode 1 of the double-layer graphite electrode pair is a solid column, and the outer graphite electrode 4 is a hollow tube. The two electrodes are coaxially aligned and inserted into the liquid pre-slag in the riser box 5; the riser box 5 is located at Above the mold 6, the mold 6 is installed on the base 7.

The upper electrode cross arm 8 and the lower electrode cross arm 9 are connected to the lifting arm 11, and the upper electrode cross arm 8 and the lower electrode cross arm 9 are connected to the control cabinet 15 through the cable 14;

The inner graphite electrode 1 is clamped by the upper holder 2, and the upper holder 2 is connected to the upper electrode cross arm 8;

The outer layer graphite electrode 4 is clamped by the lower holder 3 , and the lower holder 3 is connected to the lower electrode cross arm 9 .

Between the upper electrode cross arm 8 and the lifting arm 11 , and between the lower electrode cross arm 9 and the lifting arm 11 , there are high temperature resistant insulating gaskets 10 .

The ratio of the cross-sectional area of the inner layer graphite electrode 1 to the cross-sectional area of the upper surface of the riser box 5 is 0.3-0.4.

The cross-sectional area of the inner graphite electrode 1 is equal to the cross-sectional area of the outer graphite electrode 4 .

The difference between the radius of the inner graphite electrode 1 and the inner radius of the outer graphite electrode 4 is 10%-20% of the radius of the inner graphite electrode 1 .

The insertion depth of the inner layer graphite electrode 1 in the liquid pre-slag is the same as the insertion depth of the outer layer graphite electrode 4 in the liquid pre-slag, which is 20 mm to 50 mm.

In this embodiment, a large steel ingot of 300 tons is produced, the material is 40Cr4, the filling time is 50 minutes, and the pouring temperature is 1560° C. The weight of the steel ingot riser box is 38 tons, the diameter of the upper end surface of the riser box is 3200mm, the diameter of the lower end surface is 3500mm, and the height of the riser box is 1000mm.

A method for performing electroslag heat sealing of a large steel ingot by using a large steel ingot electroslag heat sealing device with evenly distributed heat sources includes the following steps:

Step 1: Determine the composition and slag thickness of the quaternary pre-melted slag according to the solidification process of the steel ingot, and use the slag melting furnace to melt the slag;

By weight, the composition of the pre-melted slag is 35% CaF ₂ , 43% Al ₂ O ₃ , 12% CaO, 10% MgO, and a slag thickness of 180mm;

Step 2: According to the diameter of the upper end surface of the riser box and the ratio of the cross-sectional area of the inner graphite electrode to the cross-sectional area of the upper end surface of the riser box 0.4, determine the radius of the inner graphite electrode to be 1012mm and the heating current to be 4000A;

Step 3: According to the radius of the inner graphite electrode and the difference between the radius of the inner graphite electrode and the inner radius of the outer graphite electrode, that is, 20% of the radius of the inner graphite electrode, it is 202.4mm, and the inner radius of the outer graphite electrode is 1214.4mm, according to The principle that the cross-sectional area of the inner graphite electrode is equal to the cross-sectional area of the outer graphite electrode determines that the inner and outer radius of the outer graphite electrode is about 1581mm;

Step 4: After the molten steel is poured, pour the liquid pre-slag into the riser box;

Step 5: Move the trolley to the side of the mold, turn on the power supply of the control cabinet, adjust the height of the lifting arm, insert the inner graphite electrode and the outer graphite electrode into the liquid pre-melted slag to a depth of 50mm, and adjust the heating current to 4000A;

Step 6: The heating current enters the upper electrode cross arm through the cable, flows into the inner graphite electrode through the upper holder, then passes through the liquid pre-melted slag, flows out from the outer graphite electrode, enters the lower electrode cross arm and passes through the lower holder, Finally, it flows back to the cable to form a loop;

Step 7: After the steel ingot is solidified, raise the lifting arm, pull out the inner graphite electrode and the outer graphite electrode, and turn off the power of the control cabinet;

Step 8: The electroslag heat sealing of the steel ingot is completed, and the lifting and demoulding of the steel ingot are carried out.

Claims (10)

1. a large-scale steel ingot electroslag heat-sealing ejection device that is uniformly distributed thermal source, comprises hydraulic pressure hold-down support, hydraulic drive bar, lifting arm, switch board and dolly; Hydraulic pressure hold-down support, switch board are installed on dolly, and lifting arm is inserted in hydraulic pressure hold-down support, and hydraulic pressure hold-down support base connects hydraulic pressure drive link, and hydraulic drive bar connects switch board;

It is characterized in that, also comprise clamper, lower gripper, top electrode transverse arm, bottom electrode transverse arm and two-layer equation graphite electrode pair;

The right internal layer graphite electrode of described two-layer equation graphite electrode is solid column, and outer graphite electrode is hollow tubular, and two electrode co-axially aligns insert in the liquid pre-melted slag in rising head case;

Described top electrode transverse arm, bottom electrode transverse arm are connected on lifting arm, and top electrode transverse arm, bottom electrode transverse arm are connected with switch board;

Described internal layer graphite electrode is clamped by upper clamper, and upper clamper is connected on top electrode transverse arm;

Described outer graphite electrode is clamped by lower gripper, and lower gripper is connected on bottom electrode transverse arm.

2. the large-scale steel ingot electroslag heat-sealing ejection device that is uniformly distributed thermal source according to claim 1, is characterized in that, between described top electrode transverse arm and lifting arm, all have high-temperature insulation pad between bottom electrode transverse arm and lifting arm.

3. the large-scale steel ingot electroslag heat-sealing ejection device that is uniformly distributed thermal source according to claim 1, is characterized in that, described internal layer graphite electrode cross-sectional area is 0.3 ~ 0.4 with the ratio of rising head case upper surface cross-sectional area.

4. the large-scale steel ingot electroslag heat-sealing ejection device that is uniformly distributed thermal source according to claim 1, is characterized in that, described internal layer graphite electrode cross-sectional area equals outer graphite electrode cross-sectional area.

5. the large-scale steel ingot electroslag heat-sealing ejection device that is uniformly distributed thermal source according to claim 1, is characterized in that, the difference of the radius of described internal layer graphite electrode and the inside radius of outer graphite electrode is 10% ~ 20% of internal layer graphite electrode radius.

6. the large-scale steel ingot electroslag heat-sealing ejection device that is uniformly distributed thermal source according to claim 1, it is characterized in that, the insertion depth of described internal layer graphite electrode in liquid pre-melted slag is identical with the insertion depth of outer graphite electrode in liquid pre-melted slag, is 20mm ~ 50mm.

7. utilize the large-scale steel ingot electroslag heat-sealing ejection device that is uniformly distributed thermal source described in claim 1 to carry out the method on large-scale steel ingot electroslag heat-sealing top, it is characterized in that, comprise the steps:

Step 1: thick according to ingot solidification manufacturing process determination quaternary pre-melted slag composition and slag, useization slag hearth slag;

Step 2: the ratio according to rising head case upper surface diameter and internal layer graphite electrode cross-sectional area with rising head case upper surface cross-sectional area, determine the size of internal layer graphite electrode radius and heating current;

Step 3: poor according to internal layer graphite electrode radius and internal layer graphite electrode radius and outer graphite electrode inside radius, equal the principle of outer graphite electrode cross-sectional area according to internal layer graphite electrode cross-sectional area, determine the interior outer radius of outer graphite electrode;

Step 4: after pouring molten steel completes, liquid pre-melted slag is poured in rising head case;

Step 5: travelling car, by mould, is connected switch board power supply, regulates lifting arm height, and internal layer graphite electrode, outer graphite electrode are inserted to liquid pre-melted slag certain depth, regulates heating current size;

Step 6: heating current enters top electrode transverse arm by cable, in process, clamper flows into internal layer graphite electrode, then through liquid pre-melted slag, flows out from outer graphite electrode, enters bottom electrode transverse arm through lower gripper, finally flows back to cable and forms loop;

Step 7: after ingot solidification finishes, raise lifting arm, extract internal layer graphite electrode, outer graphite electrode, closing control cabinet power supply;

Step 8: the heat-sealing of steel ingot electroslag has been pushed up, and carries out lifting and the demoulding work of steel ingot.

8. the method on large-scale steel ingot electroslag heat-sealing according to claim 7 top, is characterized in that, described quaternary pre-melted slag composition is CaF₂、Al₂O₃, CaO and MgO, by weight, CaF₂Account for 25 ~ 35%, Al₂O₃Accounting for 30 ~ 45%, CaO accounts for 10 ~ 20%, MgO and accounts for 10 ~ 20%.

9. the method on large-scale steel ingot electroslag according to claim 7 heat-sealing top, is characterized in that, the slag of described liquid pre-melted slag is thick is 100 ~ 200mm.

10. the method on large-scale steel ingot electroslag heat-sealing according to claim 7 top, is characterized in that, described electroslag heating is used single-phase alternating current, supply frequency is 50Hz, determine heating current size according to rising head case size, in the time that rising head case upper surface diameter is less than 1800mm, electric current is 2000A; In the time that rising head case upper surface diameter is 1801 ~ 2300mm, electric current is 2500A; In the time that rising head case upper surface diameter is 2301 ~ 3000mm, electric current is 3000A; In the time that rising head case upper surface diameter is greater than 3000mm, electric current is 4000A.