Smelting device for extra-thick plate type casting blank

Abstract

The utility model discloses a smelting device for an extra-thick plate type casting blank. The smelting device comprises a coaxial rotary support arm, a chuck, an atmosphere protection cover, a conductive metal pipe, a water-cooling metal cover and a crystallizer, the chuck is arranged on the coaxial rotary support arm; the chuck is detachably connected with the atmosphere protection cover; the conductive metal tube is arranged in the atmosphere protection cover; the atmosphere protection cover, the water cooling metal cover and the crystallizer are sequentially arranged from top to bottom. According to the utility model, large-tonnage extra-thick plate type casting blanks can be produced, the production quality and the production efficiency are improved, the service life of the high-temperature-resistant corrugated pipe is remarkably prolonged, and the high-temperature-resistant corrugated pipe can be used for more than 1000 times.

Description

Technical Field

[0001] The utility model belongs to the field of iron and steel metallurgy, and particularly relates to a melting device for extra-thick slab-shaped casting blanks. Background Art

[0002] In the field of iron and steel production, the manufacture of extra-thick slab-shaped casting blanks is a very challenging task for high-performance steels such as die steel, high-carbon steel, and nickel-based alloys. In order to ensure that the final product can meet the expected performance standards, these steels have extremely strict requirements for internal quality and purity.

[0003] Currently, continuous casting and ingot casting methods are generally used for the preparation of extra-thick slab-shaped casting blanks. When using continuous casting technology to produce extra-thick slab-shaped casting blanks, problems such as insufficient straightening force in the arc section are often encountered. This not only makes it difficult for the casting blank to be effectively bent, but also prone to central segregation and looseness. When the solidification angle has a large undercooling tendency, internal and surface cracks are extremely likely to occur during the bending and straightening processes. And during the pouring of ingot casting technology, it is exposed to the air, which is easy to cause secondary oxidation, resulting in an increase in the content of inclusions and oxygen and nitrogen. These all pose a threat to the purity of the casting blank. Especially due to the existence of defects such as ingot casting shrinkage cavities and solidification segregation, the rejection rate of ingot casting remains high, which not only increases production costs but also seriously affects production efficiency. The prior art discloses a steel ingot remelting device, in which a non-consumable electrode passes through a hose, and the upper connecting plate of the hose is fixed to the non-consumable electrode. In the actual production process, after each furnace is melted, the non-consumable electrode needs to be removed and a new metal base material needs to be welded. Since the hose is fixedly arranged on the non-consumable electrode, the hose must be removed when welding the metal base material. However, there are protrusions on the non-consumable electrode, and frequent disassembly is extremely likely to scratch the hose, reducing its lifespan. In addition, this remelting device has a single arm. If extra-thick slab-shaped casting blanks are to be produced, the height of the square billet needs to be increased, which will greatly increase the load-bearing capacity and operation difficulty of the single arm, and there are certain safety problems. Therefore, in view of the above problems and technical requirements, the iron and steel industry urgently needs to explore new melting technologies for extra-thick slab-shaped casting blanks. Summary of the Utility Model

[0004] Aiming at the above problems, the purpose of the utility model is to provide a melting device for extra-thick slab-shaped casting blanks, which can produce large-tonnage extra-thick slab-shaped casting blanks, improve production quality and production efficiency, and significantly improve the service life of high-temperature resistant bellows.

[0005] The technical solution adopted by the utility model to solve its technical problems is:

[0006] A melting device for extra-thick slab-shaped billets, comprising a coaxial rotating arm, a chuck, an atmosphere protection cover, a conductive metal tube, a water-cooled metal cover, and a mold; the chuck is arranged on the coaxial rotating arm; the chuck is detachably connected to the atmosphere protection cover; the conductive metal tube is arranged inside the atmosphere protection cover; the atmosphere protection cover, the water-cooled metal cover, and the mold are arranged in sequence from top to bottom.

[0007] As common knowledge, the melting device for extra-thick slab-shaped billets of the present utility model has the basic components and structures of a conventional heavy melting furnace, such as a power supply, a sensor, a transformer, a liquid slag pool, a metal melting pool, and a bottom water tank.

[0008] In the present utility model, two melting components, namely a chuck, an atmosphere protection cover, and a conductive metal tube, can be fixed on the coaxial rotating arm. During actual use, multiple square billets are welded side by side on the conductive metal tube, and the chuck holds the conductive metal tube. After each furnace is melted, the coaxial rotating arm rotates, and the un-melted square billets are placed into the mold to achieve alternating melting, so as to complete the preparation of extra-thick slab-shaped billets and improve production efficiency.

[0009] In the present utility model, the chuck is detachably connected to the atmosphere protection cover, and the conductive metal tube is arranged inside the atmosphere protection cover. During actual use, after each furnace is melted, only the atmosphere protection cover needs to be retracted to obtain the conductive metal tube for welding new square billets, which solves the problem that the existing technology requires frequent disassembly of the atmosphere protection cover, resulting in scratching, extends the service life of the atmosphere protection cover, and only needs to be replaced when the atmosphere protection cover is normally used and aged.

[0010] Furthermore, the coaxial rotating arm comprises two arms; the two arms are connected by a rotating device. Specifically, the rotating device comprises a motor and a gear, and the motor drives the gear to rotate the arms. The specific connection method and usage method are conventional technologies and do not affect the understanding of the present utility model by those skilled in the art. During actual use, other methods can also be used as long as the rotation of the two arms can be achieved to realize alternating melting and improve production efficiency.

[0011] Preferably, a flange is provided on the chuck; the atmosphere protection cover comprises a high-temperature resistant bellows; a fixing plate is provided at the upper end of the high-temperature resistant bellows, and a connecting plate is provided at the lower end; the flange is detachably connected to the fixing plate.

[0012] In this utility model, the high-temperature resistant corrugated pipe is an existing product, and its connection with the fixed plate and the connecting plate can be achieved through conventional fixing parts or other methods, as long as the connection between the high-temperature resistant corrugated pipe and the fixed plate and the connecting plate can be realized; the length of the high-temperature resistant corrugated pipe when unfolded is greater than or equal to the height from the water-cooled metal cover to the fixed plate. When not in production application, it is in a contracted state and is located above the water-cooled metal cover. During production application, the high-temperature resistant corrugated pipe is unfolded to connect the connecting plate with the water-cooled metal cover. According to the actual situation, the connection between the connecting plate and the water-cooled metal cover can be achieved by the step structure of the connecting plate (directly) resting on the water-cooled metal cover, or by using conventional fixing parts, or by using other methods, as long as the high-temperature resistant corrugated pipe, the water-cooled metal cover, and the mold are connected; as the conductive metal pipe moves up and down, the high-temperature resistant corrugated pipe can freely contract and expand, so as to keep the atmosphere protection state inside the device.

[0013] In this utility model, the flange is detachably connected to the fixed plate by bolts. Specifically, 4 to 8 pairs of opposed openings are provided on the flange and the fixed plate, preferably 5 to 7, and 1 to 2 pairs of opposed openings are reserved as the water inlet and outlet of the conductive metal pipe. The remaining pairs of opposed openings are used for the fixation of bolts. In actual use, other connection methods can also be used as long as the detachable connection between the flange and the fixed plate can be realized, so as to facilitate the disassembly and replacement of the high-temperature resistant corrugated pipe.

[0014] Preferably, a telescopic device is provided between the fixed plate and the connecting plate. The telescopic device facilitates the contraction and expansion of the high-temperature resistant corrugated pipe.

[0015] Preferably, the conductive metal pipe is of a hollow structure; water inlets and outlets are provided on the conductive metal pipe. Further preferably, the water inlets and outlets are of a three-way pipe structure; one end of the three-way pipe structure is connected to the conductive metal pipe, and the other end is located outside the atmosphere protection cover. Still further preferably, one end of the three-way pipe structure is connected to the conductive metal pipe, and the other end passes through the flange on the chuck. In actual use, a coolant is introduced into the conductive metal pipe to reduce the surface and surrounding temperature of the conductive metal pipe and extend the service life of the high-temperature resistant corrugated pipe. When the coolant vaporizes, the steam overflows through the three-way pipe structure to keep the normal pressure state inside the conductive metal pipe.

[0016] Preferably, a heat insulation plate is provided on the upper surface of the water-cooled metal cover. The heat insulation plate is used to block the heat radiation and most of the soot in the mold from flowing into the high-temperature resistant flexible corrugated pipe and prevent damage to the high-temperature resistant corrugated pipe. In actual use, the conductive metal pipe passes through the heat insulation plate and is in clearance fit with the heat insulation plate. A small amount of soot overflows through the clearance and enters the high-temperature resistant corrugated pipe, and the soot is collected and removed through the dust removal port to reduce the load of the dust removal equipment and the dust pollution in the workshop.

[0017] Preferably, a dust removal port is provided above the water-cooled metal cover. Specifically, the dust removal port is provided on the upper surface of the water-cooled metal cover. The dust removal port is an "L"-shaped pipe, the upper end of which is connected to a high-temperature resistant corrugated pipe, and the other end is connected to a dust removal device (existing device). The specific connection method and dust removal method are conventional technologies. During actual production, the connecting plate is connected to the water-cooled metal cover, and there is a gap between the connecting plate and the heat insulation plate. According to the actual situation, the connection between the connecting plate and the water-cooled metal cover can be achieved by the stepped structure of the connecting plate (directly) resting on the water-cooled metal cover, or by using conventional fixing parts for fixed connection, or by using other methods, as long as the high-temperature resistant corrugated pipe, the water-cooled metal cover, and the mold are connected. Through the dust removal port, the dust in the high-temperature resistant corrugated pipe can be collected and removed, reducing the load of the dust removal device and the dust pollution in the workshop.

[0018] Furthermore, functional openings are provided on the side wall of the water-cooled metal cover. Such as conventional slag adding ports, argon adding ports, oxygen measuring ports, and deoxidizer ports. The whole process of the device operation is protected by argon. The argon flow is adjusted according to the oxygen content measured by the oxygen measuring port. When the argon is excessive, it flows out through the dust removal port, so that the device maintains a slightly positive pressure state filled with argon. An appropriate amount of deoxidizer is added to the device through the deoxidizer port for slag deoxidation to prevent the oxidation and burning loss of active elements and the oxygen increase in extra-thick slab type billets.

[0019] Preferably, the melting device for the extra-thick slab type billet is powered by a single power supply with a double circuit; an insulating plate is provided between the water-cooled metal cover and the mold. Specifically, the single power supply with a double circuit is transformer - square billet - liquid slag pool - metal molten pool - bottom water tank - transformer and transformer - square billet - liquid slag pool - mold - transformer. The insulating plate divides the device into two parts. The area above the water-cooled metal cover and above is the inert gas protection area, and the inside of the mold is the mold melting area to improve the melting effect. The single power supply with a double circuit optimizes the temperature distribution inside the mold. By controlling the Joule heat, the shape of the metal molten pool is flattened, which helps to reduce surface defects, improve the internal segregation of the extra-thick slab type billet, and can produce extra-thick slab type billets with smooth surfaces, pure interiors, and low segregation, meeting the strict requirements in the production of high-performance materials. The specific operation method is a conventional technology.

[0020] Due to the application of the above technical solution, the beneficial effects of the present utility model compared with the prior art are as follows: First, by setting up an atmosphere protection cover for atmosphere protection, secondary oxidation is avoided, and the production of extra-thick slab-shaped casting billets with ultra-high purity is realized. In particular, the atmosphere protection cover and the chuck are detachably connected, and the conductive metal tube is arranged inside the atmosphere protection cover, so there is no need to frequently disassemble the atmosphere protection cover, significantly extending the service life of the high-temperature resistant corrugated pipe, and the available number of uses is higher than 1000 times. Second, through the method of coaxial rotary arm alternating melting, multiple square billets are welded side by side on the conductive metal tube, which not only reduces the load-bearing of a single arm and the length of the square billet, extends the service life of the device, but also efficiently utilizes heat energy, improves production efficiency, and can produce extra-thick slab-shaped casting billets with large tonnage. Third, the present utility model significantly reduces the rejection rate caused by defects such as shrinkage cavities and solidification segregation through precise control of the melting atmosphere and the application of advanced power supply circuit technology. Description of the Drawings

[0021] Figure 1 is the structural schematic diagram of the melting device for extra-thick slab-shaped casting billets during use.

[0022] Figure 2 is the structural schematic diagram of the melting device for extra-thick slab-shaped casting billets when not in use.

[0023] Figure 3 is the carbide distribution diagram of the extra-thick slab-shaped casting billet prepared by the present utility model.

[0024] [[ID=!7]] Figure 4 is the carbide distribution diagram of the extra-thick slab-shaped casting billet prepared by the existing thick slab continuous casting machine.

[0025] Figure 5 is the carbide distribution diagram of the extra-thick slab-shaped casting billet prepared by the existing die casting.

[0026] Among them: coaxial rotary arm 1, chuck 2, atmosphere protection cover 3, conductive metal tube 4, water-cooled metal cover 5, mold 6, square billet 7, liquid slag pool 8, metal melting pool 9, bottom water tank 10, flange 11, heat insulation board 12, insulating board 13, casting billet 14, arm 101, rotary device 102, fixing plate 301, connecting plate 302, high-temperature resistant corrugated pipe 303, bolt 304, telescopic device 305, tee pipe structure 401, slag addition port 501, argon addition port 502, oxygen measurement port 503, deoxidizer port 504, dust removal port 505, water-cooled metal cover water inlet 506, water-cooled metal cover water outlet 507, mold water inlet 601, mold water outlet 602. Detailed Embodiment

[0027] The present utility model will be further described below in conjunction with the accompanying drawings and embodiments. The specific components involved are existing products, and the connections and usage methods between the specific components are conventional technologies. For the sake of simplicity, some conventional components are not specifically marked in the drawings, which does not affect the understanding of the present utility model by those skilled in the art. For the same product used in the present utility model, only one place is marked in the drawings.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present utility model belongs; the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. For example, the orientations or positions indicated by terms such as "upper", "lower", "horizontal", "top", "bottom", "inner", etc. are based on the orientations or positions shown in the drawings, and are only for convenience of description and cannot be construed as a limitation to the technical solution of the present application. Embodiment 1

[0029] As Figures 1 to 2 shown:

[0030] A melting device for extra-thick slab-shaped billets includes a coaxial rotary arm 1, a chuck 2, an atmosphere protection cover 3, a conductive metal tube 4, a water-cooled metal cover 5, and a mold 6; the chuck is provided on the coaxial rotary arm; the chuck is detachably connected to the atmosphere protection cover; the conductive metal tube is provided inside the atmosphere protection cover; the atmosphere protection cover, the water-cooled metal cover, and the mold are arranged in sequence from top to bottom. The conductive metal tube is a conductive steel tube.

[0031] The conductive steel tube and the mold used in the present utility model are both standardized products widely used in the field of steel manufacturing, which helps to ensure the compatibility of the device and the convenience of maintenance, can more easily obtain replacement parts in the market, reduce the downtime of the device, and improve production efficiency. In addition, there are also conventional power supplies, sensors, square billets 7, liquid slag pools 8, metal melting pools 9, and bottom water tanks 10. During production applications, 3 square billets are welded in parallel at the bottom of the conductive steel tube. The specific operation methods and testing methods are all conventional methods in this field. Some conventional components are not shown in the present utility model, and those skilled in the art can make conventional selections according to the technical ideas of the present utility model.

[0032] The coaxial rotary arm includes two arms 101; the two arms are connected by a rotary device 102. The rotary device includes a motor and gears, and the motor drives the gears to rotate the arms. The specific connection method and usage method are conventional technologies and do not affect the understanding of the present utility model by those skilled in the art. Each arm is fixed with a set of melting components, namely a chuck, an atmosphere protection cover, and a conductive steel tube.

[0033] The chuck is provided with a flange 11; the atmosphere protection cover includes a fixed plate 301, a connecting plate 302, and a high-temperature resistant corrugated pipe 303; the upper and lower ends of the atmosphere protection cover are respectively connected to the fixed plate and the connecting plate; the flange and the fixed plate are detachably connected by bolts 304.

[0034] Both the flange and the fixed plate are provided with 5 pairs of opposed openings, and 1 pair of opposed openings is reserved as the water inlet and outlet of the conductive steel pipe, and the other 4 pairs of opposed openings are used for the fixation of bolts, so as to realize the stable and reliable connection between the flange and the fixed plate, and at the same time, it is convenient for users to install, maintain and upgrade, improving the practicability and economy of the entire melting system. The high-temperature resistant corrugated pipe is an existing product and can be selected according to needs. The connection between the high-temperature resistant corrugated pipe and the fixed plate and the connecting plate can be connected by conventional fixing parts or other methods as long as the connection between the high-temperature resistant corrugated pipe and the fixed plate and the connecting plate can be realized. The length of the high-temperature resistant corrugated pipe when unfolded is greater than the height from the water-cooled metal cover to the fixed plate. When not in production application, it is in a contracted state and is located above the water-cooled metal cover, as Figure 2 shown; during production application, the high-temperature resistant corrugated pipe is unfolded to connect the connecting plate and the water-cooled metal cover. According to the actual situation, the connecting plate directly rests on the water-cooled metal cover by using its own step structure. The high-temperature resistant corrugated pipe, the water-cooled metal cover, and the mold are connected, as Figure 1 shown; as the conductive steel pipe moves up and down, the high-temperature resistant corrugated pipe is contracted and unfolded by using a lifting motor.

[0035] A telescopic device 305 is provided between the fixed plate and the connecting plate. The telescopic device is a lifting motor, and the connection and usage method of the lifting motor are conventional technologies and do not affect the understanding of the present utility model by those skilled in the art.

[0036] The conductive steel pipe is of a hollow structure; the conductive steel pipe is provided with a water inlet and an outlet; the water inlet and the outlet are of a three-way pipe structure 401; one end of the three-way pipe structure is connected to the conductive steel pipe, and the other end passes through the opposed openings reserved on the flange of the chuck.

[0037] The upper surface of the water-cooled metal cover is provided with a heat insulation plate 12. The heat insulation plate is of a spliced annular structure. During actual use, the conductive metal pipe passes through the heat insulation plate and is in clearance fit with the heat insulation plate.

[0038] The upper surface of the water-cooled metal cover is provided with a dust removal port 505. The dust removal port is an "L"-shaped pipe, the upper end of which is connected to the high-temperature resistant corrugated pipe, and the other end is connected to a dust removal device (existing device). The specific connection method and dust removal method are conventional technologies. During actual production, the connecting plate directly rests on the water-cooled metal cover by using its own step structure and has a gap with the heat insulation plate. Through the dust removal port, the dust in the high-temperature resistant corrugated pipe can be collected and removed, reducing the load of the dust removal device and the dust pollution in the workshop.

[0039] Function openings are provided on the side wall of the water-cooled metal cover. Such as the conventional slag addition port 501, argon addition port 502, oxygen measurement port 503, and deoxidizer port 504.

[0040] The melting device for the extra-thick slab type continuous casting billet is powered by a single power supply with a double circuit; an insulating board 13 is provided between the water-cooled metal cover and the mold. The single power supply with a double circuit is transformer - square billet - liquid slag pool - metal molten pool - bottom water tank - transformer, and transformer - square billet - liquid slag pool - mold - transformer.

[0041] The specific usage method of the melting device for the extra-thick slab type continuous casting billet of the present utility model is as follows:

[0042] (1) Place the water-cooled metal cover on the mold. The flange and the fixing plate are detachably connected by bolts. Two chucks clamp the conductive steel pipe for welding 3 square billets. The high-temperature resistant corrugated pipe is in a contracted state, separating the heat insulation board;

[0043] (2) Adjust the height of the support arm. Pass the square billet and the conductive steel pipe above the water-cooled metal cover through the heat insulation board. Place the square billet in the mold. Restore the heat insulation board. The lifting motor unfolds the high-temperature resistant corrugated pipe. Place the connecting plate on the water-cooled metal cover. The high-temperature resistant corrugated pipe, the water-cooled metal cover, and the mold are connected;

[0044] (3) Sequentially pass cooling liquid into the conductive steel pipe, the water-cooled metal cover, and the mold. Fill argon gas into the device through the argon addition port and add pre-melted slag into the mold through the slag addition port. At this time, the square billet is located in the pre-melted slag. Close the power switch;

[0045] (4) The pre-melted slag melts to form a liquid slag pool. The square billet melts into droplets under the resistance Joule heat of the liquid slag pool. The droplets pass through the liquid slag pool and gather to form a metal molten pool, and form a continuous casting billet 14 under the cooling of the mold;

[0046] (5) After the square billet melting is completed, the lifting motor retracts the high-temperature resistant corrugated pipe, separates the heat insulation board, removes the conductive metal pipe from the water-cooled metal cover. The slewing device rotates the support arm. Repeat step (2) multiple times to complete the preparation of the extra-thick slab type continuous casting billet.

[0047] (6) During the implementation of process (4), a small amount of soot overflows through the gap between the conductive steel pipe and the heat insulation board and enters the high-temperature resistant corrugated pipe. There is a gap between the connecting plate and the heat insulation board. The dust removal port is connected to the high-temperature resistant corrugated pipe. Collect and remove the soot through the dust removal port. Adjust the argon gas flow according to the oxygen content measured by the oxygen measurement port. When the argon gas is excessive, it flows out through the dust removal port. When the oxygen content of the square billet is too high, add an appropriate amount of deoxidizer into the device through the deoxidizer port.

[0048] Application experiment

[0049] The mold of the melting device for extra-thick slab-shaped billets has dimensions of 1.5 m × 0.6 m × 2.5 m (length × width × height), and has the ability to produce 15-t extra-thick steel ingots; the insulating plate has dimensions of 1.6 m × 0.7 m (length × width) and an inner diameter of 0.37 m; the height of the water-cooled metal cover is 1.5 m, and the square billet is made of AISI H13 steel with dimensions of 0.35 m × 0.35 m × 2.7 m (length × width × height); the outer diameter of the conductive steel pipe is 0.35 m and the height is 3.3 m; the premelted slag includes CaF2, Al2O3 and CaO, with a mass ratio of 50:30:20 and a total mass of 480 kg. During the remelting process, the solidification rate of the molten steel is controlled at 600 kg / h, and the rest are conventional techniques in the steelmaking field.

[0050] The device of Example 1 is used to prepare the extra-thick slab-shaped billet.

[0051] Place the water-cooled metal cover on the mold. The flange and the fixed plate are detachably connected by bolts. Two chucks clamp and weld the conductive steel pipe of 3 square billets, and separate the insulating plate; adjust the height of the support arm, pass the square billet and the conductive steel pipe above the water-cooled metal cover through the insulating plate, place the square billet in the mold, restore the insulating plate, and the lifting motor unfolds the high-temperature resistant bellows. The connecting plate is placed on the water-cooled metal cover; sequentially pass cooling liquid into the conductive steel pipe, the water-cooled metal cover and the mold, fill argon gas into the device through the argon injection port, and add premelted slag into the mold through the slag addition port. At this time, the square billet is located in the premelted slag, and close the power switch; the premelted slag melts to form a liquid slag pool, the square billet melts into droplets under the resistance Joule heat of the liquid slag pool, the droplets pass through the liquid slag pool and gather to form a metal molten pool, and a billet is formed under the cooling of the mold; after the square billet is melted, the lifting motor retracts the high-temperature resistant bellows, separates the insulating plate, removes the conductive steel pipe from the water-cooled metal cover, and the slewing device rotates the support arm. Repeat the above once, and a total of 6 square billets are melted, and a 15-t extra-thick slab-shaped billet is formed under the cooling of the mold.

[0052] The prepared 15-t extra-thick slab-shaped billet is subjected to conventional forging and heat treatment, and the oxygen content in the steel is 0.0009% and the hydrogen content is less than 0.0001%. The extra-thick slab-shaped billet prepared by the present utility model has good quality, and no obvious central shrinkage cavity, central segregation, and corner cracks are found. The tissue grading is shown in Table 1, and it is observed that the carbide distribution is uniform and the size is small, as Figure 3 shown. At the same time, the surface and surrounding temperature of the conductive steel pipe are low, the high-temperature resistant bellows are durable, and the available number of uses is higher than 1000 times. The dust pollution situation in the workshop is significantly improved, and the average amount of dust collected by the dust removal equipment is 100 g / furnace.

[0053] Table 1 Tissue grading of the extra-thick slab-shaped billet prepared by the present utility model

[0054]

[0055] Comparative Example 1

[0056] An existing thick slab continuous casting machine is used to prepare a 15t extra-thick slab of 600mm×1500mm×2200mm according to an existing method.

[0057] The prepared 15t extra-thick plate blank was subjected to conventional forging and heat treatment, and the oxygen content in the steel was 0.0022% and the hydrogen content was 0.0007%. The surface quality of the extra-thick plate blank was poor, far inferior to the application experiment, and central shrinkage and central segregation were found. The microstructure rating is shown in Table 2. Large-sized carbides were observed, such as Figure 4 shown.

[0058] Table 2 Microstructure rating of extra-thick slabs produced using existing thick slab continuous casting machines

[0059]

[0060] Comparative Example 2

[0061] By using the existing mold casting and according to the existing method, a 15t extra-thick plate-shaped ingot with a size of 600mm×1500mm×2200mm was prepared.

[0062] The surface quality of the extra-thick plate casting is poor, far inferior to the application experiment, and central shrinkage and central segregation are found. The organizational rating is shown in Table 3. Large-sized carbides are observed, such as Figure 5 shown.

[0063] Table 3 Microstructure rating of extra-thick plate blanks produced using existing die casting

[0064]

[0065] Comparative Example 3

[0066] The high temperature resistant corrugated pipe of the first embodiment is connected to a conductive steel pipe, and the conductive steel pipe passes through the high temperature resistant corrugated pipe, and the rest remains unchanged.

[0067] With reference to the above preparation method, a 15t extra-thick plate casting was obtained.

[0068] The prepared 15t extra-thick plate ingot was subjected to conventional forging and heat treatment, and the various data obtained were similar to those in Example 1. However, the atmosphere protection cover needed to be removed after each smelting. As a result, the number of times the high-temperature resistant bellows could be used was reduced to only 300 times. The high replacement frequency affected the production speed and increased the production cost.

[0069] Comparative Example 4

[0070] The coaxial rotating support arm of the first embodiment is changed into a single support arm, and the rest remains unchanged.

[0071] Referring to the above preparation method, single-arm melting is adopted. If a super-thick slab-shaped billet of the same quality as that in the application experiment is to be prepared, the height of the square billet needs to be increased to 5.4 m. Correspondingly, the heights of the water-cooled metal cover and the conductive steel pipe also need to be increased, resulting in a significant increase in the load-bearing capacity of the arm, the hoisting height, and the operation difficulty, and also bringing certain safety problems.

[0072] Comparative Example 5

[0073] Change the single power supply with double circuits in Example 1 to a single power supply with a single circuit, and the rest remains unchanged.

[0074] Referring to the above preparation method, a 15-t super-thick slab-shaped billet is obtained.

[0075] The prepared 15-t super-thick slab-shaped billet is subjected to conventional forging and heat treatment, and the oxygen content in the steel is 0.0013% and the hydrogen content is 0.0003%. The surface quality of the super-thick slab-shaped billet is poor, far inferior to that in the application experiment, and central shrinkage cavities and central segregation are found. The microstructure rating is shown in Table 4.

[0076] Table 4 Microstructure rating of the super-thick slab-shaped billet prepared with a single power supply and a single circuit

[0077]

[0078] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A melting device for extra-thick slab-shaped cast billets, characterized in that: It includes a coaxial rotary arm, a chuck, an atmosphere protection cover, a conductive metal tube, a water-cooled metal cover, and a mold; the chuck is arranged on the coaxial rotary arm; the chuck is detachably connected to the atmosphere protection cover; the conductive metal tube is arranged inside the atmosphere protection cover; the atmosphere protection cover, the water-cooled metal cover, and the mold are arranged in sequence from top to bottom.

2. The melting device for the extra-thick slab type casting blank according to claim 1, characterized in that: The coaxial rotary arm includes two arms; the two arms are connected by a rotary device.

3. The melting device for extra-thick slab type continuous casting billets according to claim 1, characterized in that: The chuck is provided with a flange; the atmosphere protection cover includes a high-temperature resistant corrugated pipe; the upper end of the high-temperature resistant corrugated pipe is provided with a fixing plate, and the lower end is provided with a connecting plate.

4. The melting device for the extra-thick slab type continuous casting billet according to claim 3, characterized in that: The flange is detachably connected to the fixing plate.

5. The melting device for extra-thick slab type continuous casting billets according to claim 3, characterized in that: A telescopic device is arranged between the fixing plate and the connecting plate.

6. The melting device for the extra-thick slab type casting blank according to claim 1, characterized in that: The conductive metal tube is of a hollow structure; the conductive metal tube is provided with a water inlet and an air outlet.

7. The melting device for extra-thick slab type casting billets according to claim 6, characterized in that: The water inlet and the air outlet are of a three-way pipe structure; one end of the three-way pipe structure is connected to the conductive metal tube, and the other end is located outside the atmosphere protection cover.

8. The melting device for the extra-thick slab type casting blank according to claim 1, characterized in that: The upper surface of the water-cooled metal cover is provided with a heat insulation plate; a dust removal port is arranged above the water-cooled metal cover.

9. The melting device for extra-thick slab type casting billets according to claim 1, characterized in that: The side wall of the water-cooled metal cover is provided with a functional opening.

10. The melting device for the extra-thick slab type casting blank according to claim 1, characterized in that: The melting device for the extra-thick slab type casting blank is powered by a single power supply with a double circuit; an insulating plate is arranged between the water-cooled metal cover and the mold.

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