Arc-shaped continuous casting space-time electromagnetic stirring device and method

Abstract

The invention relates to an arc-shaped continuous casting space-time electromagnetic stirring device and method.The electromagnetic stirring device comprises a foot roller, a secondary cooling area, a solidification tail end and a plurality of electromagnetic stirring assemblies; the electromagnetic stirring assembly comprises a coil, an axial magnet yoke and a radial magnet yoke; the axial magnet yoke is fixedly mounted on the back of the radial magnet yoke, so that the electromagnetic stirring assemblies mounted in the secondary cooling area are connected in series; alternating current is applied to each coil, induced magnetic lines of force flow through the radial magnet yokes and the axial magnet yokes, a superimposed magnetic field moving in the radial direction and the axial direction is generated, the superimposed magnetic field interacts with the induced current to form spirally upward electromagnetic force, and molten metal is driven to move spirally. A flow field and a temperature field in a casting blank are improved, a stirring area is enlarged, and center porosity, shrinkage cavities and segregation are reduced. Compared with the prior art, the device has the advantages of integration of multiple functions, enlargement of a stirring area, flexible and adjustable parameters, defect control, high universality and the like.

Description

Technical Field

[0001] The invention relates to the technical field of continuous casting in iron and steel metallurgy, and in particular to a device and method for arc continuous casting time-space electromagnetic stirring. Background Art

[0002] With the continuous advancement of modern continuous casting technology, different fields have higher requirements for the quality of continuous casting billets. However, problems such as center segregation and center porosity often occur in production practice. Center segregation is a selective crystallization phenomenon caused by the different solubility of solid and liquid phases during the solidification of molten steel. The solute precipitates at the solidification front, which increases the solute concentration in the molten steel, and the solute cannot fully diffuse in the liquid phase. Therefore, a high-concentration segregation layer is formed at the solidification front, causing segregation. To solve the problem of center segregation, it is necessary to optimize the internal flow field of the billet and uniformize the composition of the molten steel. These problems are very likely to have an adverse effect on the uniformity of the performance of the finished product, so how to produce continuous casting billets with uniform composition and excellent solidification structure has always been the unremitting pursuit of metallurgical workers.

[0003] Electromagnetic stirring technology is a metallurgical technology that uses electromagnetic force generated by electromagnetic stirring devices installed on continuous casting machines to enhance the flow of molten steel in the liquid phase cavity of the ingot during continuous casting. At present, electromagnetic stirring technology has become a very important technical means to improve the quality of ingots and expand the range of varieties. According to the installation location, it can be divided into mold electromagnetic stirring (M-EMS), secondary cooling zone electromagnetic stirring (S-EMS) and solidification end electromagnetic stirring (F-EMS). Among them, the crystallizer electromagnetic stirring is mainly used to improve the flow field in the crystallizer, eliminate the superheat of molten steel and remove inclusions, while the secondary cooling zone electromagnetic stirring and solidification end electromagnetic stirring are mainly used to eliminate the quality defects such as central segregation, central porosity and V-type segregation of the ingot. According to the magnetic field type, it can be divided into rotating magnetic field type electromagnetic stirrer, traveling wave magnetic field type electromagnetic stirrer and spiral magnetic field type electromagnetic stirrer. Studies have found that the application of rotating magnetic field and traveling wave magnetic field electromagnetic stirring can improve the central segregation and shrinkage of the ingot, but the application of rotating magnetic field is easy to produce white bright bands on the cross section of the ingot, and the traveling wave magnetic field is limited by the on-site space and is not easy to install.

[0004] In actual production, in order to produce high-quality ingots, a combination of M-EMS and S-EMS or F-EMS is used. However, the installation position of the electromagnetic stirrer in these methods is relatively fixed and cannot change with the change of continuous casting process parameters (steel type, pulling speed, pouring temperature and secondary cooling water distribution, etc.). Only by adjusting the stirring current, frequency, etc. to meet the changes of different continuous casting process parameters, the metallurgical effect of continuous casting electromagnetic stirring cannot be fully exerted. At the same time, the above method uses two sets of electromagnetic stirring devices, which consumes a lot of energy. For this reason, Chinese patents CN102825245A and CN115533058A disclose a method of forming a spiral magnetic field by changing the shape of the yoke so that the end face of the yoke is tilted and the end face of the yoke is arranged up and down relative to the yoke back; Patent No. CN115533058A discloses a traveling wave magnetic field that makes the rotating magnetic field tilt along the axial direction of the ingot, and the coupling magnetic field formed has a side spiral stirring effect that is tilted to the cross section of the ingot. Although only one set of devices is needed to form a spiral magnetic field and promote spiral motion of molten steel, thus greatly reducing energy consumption, their installation positions are fixed, the flow field area affected by the electromagnetic force is small, and the stirring area cannot be effectively expanded.

[0005] Patent CN202111141334.7 discloses a vertical continuous casting time-space electromagnetic stirring mode control method and device, which can realize long-range cross-region and short-range spiral electromagnetic stirring by adjusting the movement speed and lifting height of the piston rod. The device includes a billet, a crystallizer, a secondary cooling zone, a solidification end, a foot roller, an electromagnetic stirrer, an upper base, a piston rod, a lifting device, a displacement sensor, a lower base, a computer, a yoke and a coil. The height of the electromagnetic stirrer is dynamically adjusted by a number of lifting devices installed at its lower part and assisted by a computer. An alternating magnetic field is generated in the billet by applying an alternating current in the coil, and an induced current is generated in the molten steel. The alternating magnetic field interacts with the induced current to generate an electromagnetic force, thereby driving the molten steel to move. However, the structure is relatively complex, the stirring effect is unstable, and the stirring area is limited. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art such as segregation of continuous casting billets, shrinkage cavities and difficulty in removing inclusions, and to provide a method and device for controlling the time-space electromagnetic stirring mode of arc continuous casting, which has multi-functional integration, expanded stirring area, flexible and adjustable parameters, defect control and strong versatility.

[0007] The present invention provides an arc-shaped continuous casting time-space electromagnetic stirring device, comprising: a foot roller, a secondary cooling zone, a solidification end, and a plurality of electromagnetic stirring components;

[0008] The electromagnetic stirring assembly comprises: a coil, an axial magnetic yoke, and a radial magnetic yoke; the axial magnetic yoke is fixedly mounted on the back of the radial magnetic yoke, so that the electromagnetic stirring assembly installed in the second cooling zone is connected in series;

[0009] By applying alternating current to each coil, the induced magnetic lines of force flow through the radial yoke and the axial yoke, generating a superimposed magnetic field moving in the radial and axial directions, which interacts with the induced current to form a spiral upward electromagnetic force, driving the metal liquid to spirally move, thereby improving the flow field and temperature field in the ingot, expanding the stirring area, and reducing central porosity, shrinkage and segregation.

[0010] Furthermore, the number of the electromagnetic stirring assemblies is 3 to 6.

[0011] Furthermore, the applied alternating current is two-phase or three-phase.

[0012] Furthermore, the excitation current of the electromagnetic stirring device is 0-2000A, and the frequency is 1-20Hz.

[0013] Furthermore, the electromagnetic stirring assembly is installed in the secondary cooling zone and the solidification end.

[0014] Furthermore, the electromagnetic stirring device is suitable for one of square billets, round billets or large round billets.

[0015] The present invention also provides a method for regulating arc continuous casting time and space electromagnetic stirring using an electromagnetic stirring device, including the following modes:

[0016] Rotating magnetic field mode: adjust the phase angles of the coils of each electromagnetic stirring assembly to be the same, apply alternating current to generate a rotating magnetic field, and drive the metal liquid to move radially;

[0017] Spiral magnetic field mode: adjust the phase angle of the coil of each electromagnetic stirring component to a preset angle difference, apply alternating current to generate an axial traveling wave magnetic field, and drive the metal liquid to spirally move.

[0018] Furthermore, in the rotating magnetic field mode, the phase angle difference of each coil is 0°, and the magnetic field acts on the cross section of the ingot to form a horizontal circulating current.

[0019] Furthermore, in the spiral magnetic field mode, the phase angle difference of each coil is greater than 0°, and the traveling wave magnetic field propagates along the axial direction of the ingot, driving the molten steel to spirally rise.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) Multifunctional integration: A single device can achieve dual-mode stirring of rotation and spiral, replacing the traditional combination of multiple devices, reducing energy consumption and maintenance costs.

[0022] (2) Expand the stirring area: The axial magnetic yoke series structure allows the magnetic field to cover the secondary cooling zone to the end of solidification, thereby strengthening the long-range metallurgical effect.

[0023] (3) Flexible and adjustable parameters: The wide range of current, frequency and phase angle can be adjusted to adapt to various working conditions and improve process adaptability.

[0024] (4) Defect control: The rotating magnetic field eliminates local segregation, and the spiral magnetic field suppresses central porosity and shrinkage, thereby comprehensively improving the internal quality of the ingot.

[0025] (5) Strong versatility: Applicable to various cross-section types such as square billets and round billets, expanding the application scenarios of the technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the three-dimensional structure of an arc-shaped continuous casting space-time electromagnetic stirring device of the present invention;

[0027] Figure 2 A schematic diagram of arc-shaped continuous casting time-space electromagnetic stirring of the present invention;

[0028] Figure 3 It is a schematic diagram of a rotating magnetic field generated by an arc-shaped continuous casting space-time electromagnetic stirring device of the present invention;

[0029] Figure 4 A schematic diagram of a spiral magnetic field generated by an arc-shaped continuous casting space-time electromagnetic stirring device of the present invention;

[0030] Figure 5 This is a diagram of electromagnetic force distribution and fluid velocity streamlines under the action of space-time electromagnetic stirring in arc continuous casting of the present invention;

[0031] Figure numerals: 1 - foot roller, 2 - second cooling zone, 3 - solidification end, 4 - electromagnetic stirring assembly, 5 - coil, 6 - axial yoke, 7 - radial yoke. DETAILED DESCRIPTION

[0032] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms and other features not clearly described in this technical solution are all considered to be common technical features disclosed in the prior art.

[0033] Example 1

[0034] This embodiment provides an arc-shaped continuous casting time-space electromagnetic stirring device, such as Figure 1 , 2 As shown, it includes: a foot roller 1, a secondary cooling zone 2, a solidification end 3, and multiple electromagnetic stirring components 4;

[0035] The electromagnetic stirring assembly 4 comprises: a coil 5, an axial magnetic yoke 6, and a radial magnetic yoke 7; the axial magnetic yoke 6 is fixedly mounted on the back of the radial magnetic yoke 7, so that the electromagnetic stirring assembly 4 installed in the second cooling zone 2 is connected in series;

[0036] By applying an alternating current to each coil 5, the induced magnetic lines of force flow through the radial magnetic yoke 7 and the axial magnetic yoke 6, generating a superimposed magnetic field moving in the radial and axial directions, which interacts with the induced current to form a spiral upward electromagnetic force, driving the metal liquid to spirally move. This improves the flow field and temperature field in the ingot, expands the stirring area, and reduces central looseness, shrinkage and segregation. The electromagnetic stirring assembly 4 is installed in the secondary cooling zone 2 and the solidification end 3.

[0037] This embodiment also provides a method for regulating arc continuous casting time and space electromagnetic stirring using an electromagnetic stirring device, including the following modes:

[0038] Rotating magnetic field mode: adjust the phase angles of the coils 5 of each electromagnetic stirring assembly 4 to be the same, apply alternating current to generate a rotating magnetic field, and drive the metal liquid to move radially;

[0039] Spiral magnetic field mode: the phase angle of the coil 5 of each electromagnetic stirring assembly 4 is adjusted to a preset angle difference, and an alternating current is applied to generate an axial traveling wave magnetic field to drive the metal liquid to spirally move.

[0040] In a specific embodiment, the size of the ingot is 180×180 square ingot, the pulling speed is 1.25m / min, and when the molten steel is pulled out from the tundish through the crystallizer to form the initial solidified ingot shell, the time-space electromagnetic stirring device is started. The device consists of three electromagnetic stirring components 4. In the time-space electromagnetic stirring device, the axial magnetic yoke 6 is installed on the back of the radial magnetic yoke 7, and the phase of the coil 5 of each electromagnetic stirring component 4 is adjusted to ensure that the phase angles of the corresponding coils 5 of each electromagnetic stirring component 4 are the same, such as Figure 3 As shown. An alternating current of 1800A and 20Hz is applied to each coil to form an induced magnetic field, which generates a rotating magnetic field in the ingot. When the molten steel flows through, it cuts the magnetic flux lines, generates a radial electromagnetic pinch force, and improves the flow field. At the same time, the electromagnetic stirring device is designed from the second cooling zone 2 to the solidification end 3 area, which can expand the stirring area and achieve the effect of improving the quality of the ingot.

[0041] Example 2

[0042] This embodiment provides an arc-shaped continuous casting time-space electromagnetic stirring device, such as Figure 1 , 2 As shown, it includes: a foot roller 1, a secondary cooling zone 2, a solidification end 3, and multiple electromagnetic stirring components 4;

[0043] The electromagnetic stirring assembly 4 comprises: a coil 5, an axial magnetic yoke 6, and a radial magnetic yoke 7; the axial magnetic yoke 6 is fixedly mounted on the back of the radial magnetic yoke 7, so that the electromagnetic stirring assembly 4 installed in the second cooling zone 2 is connected in series;

[0044] By applying an alternating current to each coil 5, the induced magnetic lines of force flow through the radial magnetic yoke 7 and the axial magnetic yoke 6, generating a superimposed magnetic field moving in the radial and axial directions, which interacts with the induced current to form a spiral upward electromagnetic force, driving the metal liquid to spirally move. This improves the flow field and temperature field in the ingot, expands the stirring area, and reduces central looseness, shrinkage and segregation. The electromagnetic stirring assembly 4 is installed in the secondary cooling zone 2 and the solidification end 3.

[0045] This embodiment also provides a method for regulating arc continuous casting time and space electromagnetic stirring using an electromagnetic stirring device, including the following modes:

[0046] Rotating magnetic field mode: adjust the phase angles of the coils 5 of each electromagnetic stirring assembly 4 to be the same, apply alternating current to generate a rotating magnetic field, and drive the metal liquid to move radially;

[0047] Spiral magnetic field mode: the phase angle of each electromagnetic stirring assembly 4 is adjusted to a preset angle difference, and an alternating current is applied to generate an axial traveling wave magnetic field to drive the metal liquid to spirally move.

[0048] In a specific embodiment, the size of the second casting is a large round billet of Φ1200mm, the pulling speed is 0.1m / min, and when the molten steel is pulled out from the tundish through the crystallizer to form an initial solidified billet shell, the time-space electromagnetic stirring device is started. The device consists of three electromagnetic stirring components 4. In the time-space electromagnetic stirring device, the axial magnetic yoke 6 is installed on the back of the radial magnetic yoke 7, and the phase of the coil 5 of each electromagnetic stirring component 4 is adjusted to ensure that the phase angle of each electromagnetic stirring component 4 corresponding to the coil 5 is 120°, such as Figure 4 As shown. An alternating current of 2000A and 18Hz is applied to each coil to form an induced magnetic field, so that the magnetic lines of force flow through the radial magnetic yoke 7 and the axial magnetic yoke 6, thereby generating a spiral magnetic field in the ingot. The molten steel cuts the magnetic lines of force when flowing through. In the direction perpendicular to the billet drawing, the rotating magnetic field generates a radial electromagnetic pinch force, causing the molten steel to form a horizontal circulation; in the direction of the billet drawing, the molten steel is subjected to an upward force under the action of the traveling wave magnetic field. The two are superimposed to form a spiral upward electromagnetic force inside the molten steel. Driven by the electromagnetic force, the molten steel moves in a spiral upward motion, as shown in FIG. Figure 5 As shown, a uniform flow field is achieved. At the same time, the electromagnetic stirring device is designed from the second cooling zone 2 to the solidification end 3 area, which can expand the stirring area and improve the quality of the ingot.

[0049] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0050] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. An arc-shaped continuous casting time-space electromagnetic stirring device, characterized in that: include: A foot roller (1), a secondary cooling zone (2), a solidification end (3), and a plurality of electromagnetic stirring components (4); The electromagnetic stirring assembly (4) comprises: a coil (5), an axial magnetic yoke (6), and a radial magnetic yoke (7); the axial magnetic yoke (6) is fixedly mounted on the back of the radial magnetic yoke (7), so that the electromagnetic stirring assembly (4) mounted in the second cooling zone (2) is connected in series; By applying an alternating current to each coil (5), the induced magnetic lines of force flow through the radial magnetic yoke (7) and the axial magnetic yoke (6), generating a superimposed magnetic field moving in the radial and axial directions, which interacts with the induced current to form a spiral upward electromagnetic force, thereby driving the metal liquid to move in a spiral manner.

2. The arc-shaped continuous casting space-time electromagnetic stirring device according to claim 1, characterized in that: The number of the electromagnetic stirring components (4) is 3 to 6.

3. The arc-shaped continuous casting time-space electromagnetic stirring device according to claim 1, characterized in that: The applied alternating current is two-phase or three-phase.

4. The arc-shaped continuous casting space-time electromagnetic stirring device according to claim 1, characterized in that: The excitation current of the electromagnetic stirring device is 0-2000A, and the frequency is 1-20Hz.

5. The arc-shaped continuous casting space-time electromagnetic stirring device according to claim 1, characterized in that: The electromagnetic stirring assembly (4) is installed in the second cooling zone (2) and the solidification end (3).

6. The arc-shaped continuous casting space-time electromagnetic stirring device according to claim 1, characterized in that: The electromagnetic stirring device is suitable for one of square billets, round billets or large round billets.

7. A method for regulating arc continuous casting time-space electromagnetic stirring using the electromagnetic stirring device according to any one of claims 1 to 6, characterized in that: The following modes are included: Rotating magnetic field mode: adjusting the phase angles of the coils (5) of the electromagnetic stirring components (4) to be the same, applying alternating current to generate a rotating magnetic field, and driving the metal liquid to move radially; Spiral magnetic field mode: the phase angle of the coil (5) of each electromagnetic stirring assembly (4) is adjusted to a preset angle difference, and an alternating current is applied to generate an axial traveling wave magnetic field to drive the metal liquid to spirally move.

8. The arc continuous casting time-space electromagnetic stirring adjustment method according to claim 7, characterized in that: In the rotating magnetic field mode, the phase angle difference of each coil (5) is 0°, and the magnetic field acts on the cross section of the ingot to form a horizontal circulating current.

9. The arc continuous casting time-space electromagnetic stirring adjustment method according to claim 7, characterized in that: In the spiral magnetic field mode, the phase angle difference of each coil (5) is greater than 0°, and the traveling wave magnetic field propagates along the axial direction of the ingot, driving the molten steel to spirally rise.

10. The arc continuous casting time-space electromagnetic stirring adjustment method according to claim 7, characterized in that: The phase angle difference is 120°, corresponding to the three-phase current power supply mode.

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