A segmented roller multi-mode electromagnetic stirring flow control device for the secondary cooling zone of continuous casting

Abstract

A segmented roller multi-mode electromagnetic stirring flow control device for the secondary cooling zone of continuous casting includes two pairs of electromagnetic stirring rollers arranged in parallel, each pair of electromagnetic stirring rollers includes an electromagnetic stirring upper roller and a lower roller, the slab is located between the two pairs of electromagnetic stirring rollers, and gaps are left between the slab and the upper roller and the lower roller; the electromagnetic stirring upper roller and the electromagnetic stirring lower roller have the same structure, both adopt a segmented roller structure, the roller body has four sections, each roller body includes an iron core and a coil, the coil is coaxially wound on the iron core, an insulating sheet is arranged between adjacent coils, and all coils are equipped with a cooling device. The present invention generates a constant alternating magnetic field by energizing the coil, forms an induced current in the molten steel, and then generates an electromagnetic force, which acts on the molten steel, promotes the fluidity of the molten steel inside the shell, drives heat transfer and solute migration, realizes the expansion of the equiaxed crystal zone, the uniformity of the solute composition, the improvement of the loose shrinkage cavity, the improvement of the solidification hysteresis, and the reduction of the generation of the "white bright band", thereby improving the quality of wide and thick slabs.

Description

Technical Field

[0001] The invention belongs to the technical field of steelmaking and continuous casting, and in particular relates to a segmented roller type multi-mode electromagnetic stirring flow control device for a secondary cooling zone of continuous casting. Background Art

[0002] As the global continuous casting ratio and slab output increase year by year, the market has higher and higher requirements for the "variety" and "quality" of slabs. Developing defect-free and efficient continuous casting is an important way to achieve low-carbon and green development of slab production lines. Due to the particularity of the slab thickness direction, defects such as center segregation, looseness and cracks have always been recognized as the most difficult quality problems to control in continuous casting production, which seriously restricts the efficient production of slabs.

[0003] The traveling wave electromagnetic stirring technology in the secondary cooling zone has the advantages of high density, cleanliness and controllability. It is a clean energy itself and can affect the atomic and molecular scales of molten steel without contact. Through the interaction forces between various magnets such as the Lorentz force and magnetic force, it can significantly affect the physical and chemical processes such as melt flow, temperature distribution, solute enrichment, grain nucleation and growth during the solidification of molten steel, thereby controlling and improving the structure of wide and thick slabs.

[0004] However, the electromagnetic stirring technology currently used by domestic and foreign steel mills is given by the equipment manufacturer, and it is impossible to adjust the electromagnetic stirring parameters according to the changes in the slab cross-sectional dimensions and process parameters. Practice has proved that only by using different stirring parameters for different cross-sectional dimensions and process parameters can the best effect be achieved. Otherwise, it is easy to have slab defects such as center segregation, frame segregation, "white bright band" negative segregation and solidification hysteresis, which seriously affect the qualified rate of product flaw detection. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a segmented roller multi-mode electromagnetic stirring flow control device in the secondary cooling zone of continuous casting, which generates a constant alternating magnetic field by energizing the coil, forms an induced current in the molten steel, and then generates an electromagnetic force. The electromagnetic force acts on the molten steel, promotes the fluidity of the molten steel inside the shell, drives heat transfer and solute migration, thereby achieving the expansion of the equiaxed crystal zone, uniform solute composition, improvement of loose shrinkage cavities, improvement of solidification hysteresis and reduction of the formation of "white bright band", thereby improving the quality of wide and thick slabs.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a segmented roller multi-mode electromagnetic stirring flow control device in the second cooling zone of continuous casting, comprising two pairs of electromagnetic stirring rollers, the two pairs of electromagnetic stirring rollers are arranged in parallel, each pair of electromagnetic stirring rollers comprises an electromagnetic stirring upper roller and an electromagnetic stirring lower roller, the slab is located between the two pairs of electromagnetic stirring rollers, and there is a gap between the slab and the electromagnetic stirring upper roller and the electromagnetic stirring lower roller; the electromagnetic stirring upper roller and the electromagnetic stirring lower roller have the same structure, both adopt a segmented roller body structure, the number of roller body sections is four, each roller body section comprises an iron core and a coil, the coil is coaxially wound on the iron core, an insulating sheet is arranged between adjacent coils, and all coils are equipped with a cooling device.

[0007] The coil is covered with a magnetic shielding sleeve, the cross-section of the magnetic shielding sleeve is C-shaped, and the C-shaped opening of the magnetic shielding sleeve faces the slab.

[0008] The iron core adopts a cylindrical structure.

[0009] The maximum value of the magnetic induction intensity at the center of the slab is not less than 0.08T.

[0010] The number of turns of the coil is 0 to 88, and the coil is made of round or flat copper wire.

[0011] Different coil windings on the same iron core use different initial current phases, the same current frequency is passed, and the power-on method is a pulse method.

[0012] The coil needs to be connected to U and V two-phase alternating current, the phase angle of the connected alternating current is 0-90°, the current is 0-800A, and the frequency is 0-100Hz; when the coil is connected to alternating current, an alternating electromagnetic field will be excited, and the alternating electromagnetic field will gradually penetrate into the interior of the slab, and then promote the flow of molten steel inside the slab through electromagnetic force; different modes of electromagnetic force are generated by changing the current phase sequence.

[0013] When the cross-sectional size of the slab is less than 1000 mm, only the two middle sections of the electromagnetic stirring upper roller and the electromagnetic stirring lower roller are turned on, the electromagnetic force direction of the two middle sections of the electromagnetic stirring upper roller is a right-left mode, and the electromagnetic force direction of the two middle sections of the electromagnetic stirring lower roller is a left-right mode. When the slab enters the action interval of the roller body, six reflow zones are formed inside the slab, wherein two reflow zones are formed in the middle area and the two end areas of the slab; or, the electromagnetic force direction of the two middle sections of the electromagnetic stirring upper roller is a right-left mode, and the electromagnetic force direction of the two middle sections of the electromagnetic stirring lower roller is a right-left mode. When the slab enters the action interval of the roller body, eight reflow zones are formed inside the slab, wherein four reflow zones are formed in the middle area of ​​the slab, and two reflow zones are formed in the two end areas.

[0014] When the cross-sectional size of the slab is between 1000mm and 1800mm, all four sections of the electromagnetic stirring upper roller and the electromagnetic stirring lower roller are turned on, and the electromagnetic force directions of all four sections of the electromagnetic stirring upper roller adopt the right-right-left-left mode, and the electromagnetic force directions of all four sections of the electromagnetic stirring lower roller adopt the right-left-left mode. When the slab enters the action interval of the roller, eight reflow zones are formed inside the slab, wherein two reflow zones are each formed in the middle area and the rear end area of ​​the slab, and four reflow zones are formed in the front end area of ​​the slab; or, the electromagnetic force directions of all four sections of the electromagnetic stirring upper roller adopt the right-left-left mode, and the electromagnetic force directions of all four sections of the electromagnetic stirring lower roller adopt the left-right-left mode. When the slab enters the action interval of the roller, twelve reflow zones are formed inside the slab, wherein four reflow zones are each formed in the middle area and the two end areas of the slab.

[0015] When the cross-sectional size of the slab is greater than 1800mm, all four sections of the electromagnetic stirring upper roller and the electromagnetic stirring lower roller are turned on, the electromagnetic force direction of all four sections of the electromagnetic stirring upper roller adopts a right-right-right-left mode, and the electromagnetic force direction of all four sections of the electromagnetic stirring lower roller adopts a right-left-left-left mode. When the slab enters the action range of the roller, seven reflow zones are formed inside the slab, a reflow zone is formed within 3 / 4 of the left rear end area of ​​the slab, a reflow zone is formed within 1 / 4 of the right rear end area of ​​the slab, a reflow zone is formed within 3 / 4 of the left middle area of ​​the slab, two reflow zones are formed within 1 / 4 of the right middle area of ​​the slab, a reflow zone is formed within 1 / 4 of the left front end area of ​​the slab, and 3 reflow zones are formed in the slab. A reflow zone is formed within the range of 3 / 4 from the right of the front end area of ​​the slab; or, the electromagnetic force directions of all four sections of the electromagnetic stirring upper roller adopt the right-right-right-left mode, and the electromagnetic force directions of all four sections of the electromagnetic stirring lower roller adopt the left-left-left-left mode. When the slab enters the action range of the roller body, six reflow zones are formed inside the slab, a reflow zone is formed within the range of 3 / 4 from the left of the rear end area of ​​the slab, a reflow zone is formed within the range of 1 / 4 from the right of the front end area of ​​the slab, a reflow zone is formed within the range of 3 / 4 from the left of the middle area of ​​the slab, a reflow zone is formed within the range of 1 / 4 from the right of the middle area of ​​the slab, a reflow zone is formed within the range of 3 / 4 from the left of the front end area of ​​the slab, and a reflow zone is formed within the range of 1 / 4 from the right of the front end area of ​​the slab.

[0016] Beneficial effects of the present invention:

[0017] The segmented roller multi-mode electromagnetic stirring flow control device in the secondary cooling zone of continuous casting of the present invention generates a constant alternating magnetic field by energizing the coil, forming an induced current in the molten steel, and then generating an electromagnetic force. The electromagnetic force acts on the molten steel, promotes the fluidity of the molten steel inside the shell, drives heat transfer and solute migration, thereby achieving the expansion of the equiaxed crystal zone, the uniformity of the solute composition, the improvement of loose shrinkage cavities, the improvement of solidification hysteresis and the reduction of the generation of "white bright bands", thereby improving the quality of wide and thick slabs.

[0018] The segmented roller multi-mode electromagnetic stirring flow control device in the continuous casting secondary cooling zone of the present invention can generate an electromagnetic force perpendicular to the direction of the slab drawing speed. This type of electromagnetic force can cause the molten steel in the multi-section slab to produce multi-mode flow and enhance heat convection. At the same time, this type of electromagnetic force has a larger action range than the traditional secondary cooling zone electromagnetic stirrer. From the metallurgical effect point of view, it is more conducive to the production of high-quality slabs and can provide sufficient freedom for continuous casting production operations. In addition, it can also minimize the risk of steel leakage, modify the end morphology of solidification, and reduce center segregation and frame segregation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a segmented roller multi-mode electromagnetic stirring flow control device for a continuous casting secondary cooling zone of the present invention;

[0020] Figure 2 A schematic diagram of the coil winding method of a segmented roller multi-mode electromagnetic stirring flow control device in a continuous casting secondary cooling zone of the present invention;

[0021] Figure 3 It is a schematic diagram of the structural decomposition of the electromagnetic stirring upper roller / lower roller of the present invention;

[0022] Figure 4 The flow field direction and electromagnetic force distribution diagram when the slab cross-section size is less than 1000 mm (Scheme 1);

[0023] Figure 5 The flow field direction and electromagnetic force distribution diagram when the slab cross-section size is less than 1000 mm (Scheme 2);

[0024] Figure 6 The flow field direction and electromagnetic force distribution diagram when the slab cross-section size is between 1000mm and 1800mm (Scheme 1);

[0025] Figure 7 The flow field direction and electromagnetic force distribution diagram when the slab cross-section size is between 1000mm and 1800mm (Scheme 2);

[0026] Figure 8 The flow field direction and electromagnetic force distribution diagram when the slab cross-section size is greater than 1800 mm (Scheme 1);

[0027] Fig. 9 The flow field direction and electromagnetic force distribution diagram when the slab cross-section size is greater than 1800 mm (Scheme 2);

[0028] In the figure, 1 is an electromagnetic stirring upper roller, 2 is an electromagnetic stirring lower roller, 3 is a slab, 4 is an iron core, 5 is a coil, and 6 is a magnetic shielding sleeve. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figures 1 to 3 As shown, a segmented roller multi-mode electromagnetic stirring flow control device for the secondary cooling zone of continuous casting includes two pairs of electromagnetic stirring rollers, which are arranged in parallel, and each pair of electromagnetic stirring rollers includes an electromagnetic stirring upper roller 1 and an electromagnetic stirring lower roller 2. The slab 3 is located between the two pairs of electromagnetic stirring rollers, and there is a gap between the slab 3 and the electromagnetic stirring upper roller 1 and the electromagnetic stirring lower roller 2; the electromagnetic stirring upper roller 1 and the electromagnetic stirring lower roller 2 have the same structure, both adopt a segmented roller body structure, the number of roller body sections is four, each roller body section includes an iron core 4 and a coil 5, the coil 5 is coaxially wound on the iron core 4, an insulating sheet is arranged between adjacent coils 5, and all coils 4 are equipped with a cooling device.

[0031] The coil 5 is coated with a magnetic shielding sleeve 6 on the outside. The cross-sectional shape of the magnetic shielding sleeve 6 is C-shaped, and the C-shaped opening of the magnetic shielding sleeve 6 faces the slab 3 .

[0032] The iron core 4 adopts a cylindrical structure.

[0033] The maximum value of the magnetic induction intensity at the center of the slab 3 is not less than 0.08T.

[0034] The number of turns of the coil 5 is 0 to 88, and the coil 5 is made of round or flat copper wire.

[0035] Different coil windings 5 ​​on the same iron core 4 use different initial current phases, the same current frequency is passed, and the power-on method is a pulse method.

[0036] The coil 5 needs to be connected to U and V two-phase alternating current, the phase angle of the connected alternating current is 0-90°, the current is 0-800A, and the frequency is 0-100Hz; when the coil 5 is connected to the alternating current, an alternating electromagnetic field will be excited, and the alternating electromagnetic field will gradually penetrate into the slab 3, and then promote the flow of molten steel inside the slab 3 through electromagnetic force; different modes of electromagnetic force are generated by changing the current phase sequence, which is conducive to actual on-site regulation.

[0037] When the cross-sectional size of the slab 3 is less than 1000 mm, only the middle two rollers of the electromagnetic stirring upper roller 1 and the electromagnetic stirring lower roller 2 are turned on, the electromagnetic force direction of the middle two rollers of the electromagnetic stirring upper roller 1 is the right-left mode, and the electromagnetic force direction of the middle two rollers of the electromagnetic stirring lower roller 2 is the left-right mode. When the slab 3 enters the action range of the rollers, six reflow zones are formed inside the slab 3, wherein two reflow zones are formed in the middle area and the two end areas of the slab 3, such as Figure 4 As shown; or, the electromagnetic force direction of the middle two sections of the electromagnetic stirring upper roller 1 is in the right-left mode, and the electromagnetic force direction of the middle two sections of the electromagnetic stirring lower roller 2 is in the right-left mode. When the slab 3 enters the action interval of the roller body, eight reflow zones are formed inside the slab 3, among which four reflow zones are formed in the middle area of ​​the slab 3, and two reflow zones are formed at each of the two end areas, as shown in FIG. Figure 5 As shown in the figure, the solute field in the molten steel is fully driven to be rationally distributed through the formed reflux zone.

[0038] When the cross-sectional size of the slab 3 is between 1000 mm and 1800 mm, all four sections of the electromagnetic stirring upper roller 1 and the electromagnetic stirring lower roller 2 are turned on, and the electromagnetic force directions of all four sections of the electromagnetic stirring upper roller 1 adopt the right-right-left-left mode, and the electromagnetic force directions of all four sections of the electromagnetic stirring lower roller 2 adopt the right-left-left mode. When the slab 3 enters the action interval of the roller body, eight reflow zones are formed inside the slab 3, wherein two reflow zones are formed in the middle area and the rear end area of ​​the slab 3, and four reflow zones are formed in the front end area of ​​the slab, such as Figure 6 As shown; or, the electromagnetic force direction of all four sections of the electromagnetic stirring upper roller 1 adopts the right-left-left mode, and the electromagnetic force direction of all four sections of the electromagnetic stirring lower roller 2 adopts the left-right-left-right mode. When the slab 3 enters the action interval of the roller body, twelve reflow zones are formed inside the slab 3, among which four reflow zones are formed in the middle area and the two end areas inside the slab 3, as shown in FIG. Figure 7 As shown in the figure, with the increase of the number of reflux zones, the graded control effect of the molten steel in each zone is better. The rationalized control of the segmentation of the electromagnetic stirring roller becomes the key to controlling segregation and white bright band.

[0039] When the cross-sectional size of the slab 3 is greater than 1800 mm, all four sections of the electromagnetic stirring upper roller 1 and the electromagnetic stirring lower roller 2 are turned on, the electromagnetic force direction of all four sections of the electromagnetic stirring upper roller 1 adopts the right-right-right-left mode, and the electromagnetic force direction of all four sections of the electromagnetic stirring lower roller 2 adopts the right-left-left-left mode. When the slab 3 enters the action range of the roller body, seven reflow zones are formed inside the slab 3, a reflow zone is formed within the 3 / 4 range from the left of the rear end area of ​​the slab 3, a reflow zone is formed within the 1 / 4 range from the right of the rear end area of ​​the slab 3, a reflow zone is formed within the 3 / 4 range from the left of the middle area of ​​the slab 3, two reflow zones are formed within the 1 / 4 range from the right of the middle area of ​​the slab 3, a reflow zone is formed within the 1 / 4 range from the left of the front end area of ​​the slab 3, and a reflow zone is formed within the 3 / 4 range from the right of the front end area of ​​the slab 3, such as Figure 8 As shown, this mode is suitable for steel grades with higher solute content; alternatively, the electromagnetic force directions of all four sections of the electromagnetic stirring upper roller 1 adopt the right-right-right-left mode, and the electromagnetic force directions of all four sections of the electromagnetic stirring lower roller 2 adopt the left-left-left-left mode. When the slab 3 enters the action interval of the roller, six reflow zones are formed inside the slab 3, a reflow zone is formed within the 3 / 4 range from the left in the rear end area of ​​the slab 3, a reflow zone is formed within the 1 / 4 range from the right in the front end area of ​​the slab 3, a reflow zone is formed within the 3 / 4 range from the left in the middle area of ​​the slab 3, a reflow zone is formed within the 1 / 4 range from the right in the middle area of ​​the slab 3, a reflow zone is formed within the 3 / 4 range from the left in the front end area of ​​the slab 3, and a reflow zone is formed within the 1 / 4 range from the right in the front end area of ​​the slab 3, as shown in FIG. Fig. 9 As shown, this mode is suitable for steels with lower solute components; the reflux zone within the 1 / 4 range of the middle area and the two end areas of the slab 3 helps to balance the acceleration of the molten steel in the reflux zone within the 3 / 4 range, thereby protecting the stability of the molten steel composition.

[0040] The solutions in the embodiments are not intended to limit the patent protection scope of the present invention. All equivalent implementations or changes that do not deviate from the present invention are included in the patent scope of this case.

Claims

1. A continuous casting secondary cooling zone segmented roller multi-mode electromagnetic stirring flow control method, which adopts a continuous casting secondary cooling zone segmented roller multi-mode electromagnetic stirring flow control device, characterized in that: The segmented roller multi-mode electromagnetic stirring flow control device in the secondary cooling zone of continuous casting comprises two pairs of electromagnetic stirring rollers, which are arranged in parallel, and each pair of electromagnetic stirring rollers comprises an electromagnetic stirring upper roller and an electromagnetic stirring lower roller, and the slab is located between the two pairs of electromagnetic stirring rollers, and there is a gap between the slab and the electromagnetic stirring upper roller and the electromagnetic stirring lower roller; the electromagnetic stirring upper roller and the electromagnetic stirring lower roller have the same structure, both adopt a segmented roller body structure, and the roller body has four sections, and each roller body includes an iron core and a coil, and the coil is coaxially wound on the iron core, and an insulating sheet is arranged between adjacent coils, and all coils are equipped with a cooling device; the coil is coated with a magnetic shielding sleeve on the outside, and the cross-sectional shape of the magnetic shielding sleeve is C-shaped, and the C-shaped opening of the magnetic shielding sleeve faces the slab; the iron core adopts a cylindrical structure; the The maximum value of the magnetic induction intensity at the center of the slab is not less than 0.08T; the number of turns of the coil is 0 to 88 turns, and the coil is made of round or flat copper wire; different coil windings on the same iron core use different initial current phases, the same current frequency is passed, and the power-on method adopts a pulse method; the coil needs to be connected to U and V two-phase alternating current, the phase angle of the connected alternating current is 0 to 90°, the current is 0 to 800A, and the frequency is 0 to 100Hz; when the coil is connected to alternating current, an alternating electromagnetic field will be excited, and the alternating electromagnetic field will gradually penetrate into the interior of the slab, and then promote the flow of molten steel inside the slab through electromagnetic force; different modes of electromagnetic force are generated by changing the current phase sequence; the continuous casting secondary cooling zone segmented roller multi-mode electromagnetic stirring flow control method is: When the cross-sectional size of the slab is less than 1000 mm, only the middle two rollers of the electromagnetic stirring upper roller and the electromagnetic stirring lower roller are turned on, the electromagnetic force direction of the middle two rollers of the electromagnetic stirring upper roller is a right-left mode, and the electromagnetic force direction of the middle two rollers of the electromagnetic stirring lower roller is a left-right mode. When the slab enters the action interval of the rollers, six reflow zones are formed inside the slab, wherein two reflow zones are formed in the middle area and the two end areas of the slab; or, the electromagnetic force direction of the middle two rollers of the electromagnetic stirring upper roller is a right-left mode, and the electromagnetic force direction of the middle two rollers of the electromagnetic stirring lower roller is a right-left mode. When the slab enters the action interval of the rollers, eight reflow zones are formed inside the slab, wherein four reflow zones are formed in the middle area of ​​the slab, and two reflow zones are formed in the two end areas; When the cross-sectional size of the slab is between 1000 mm and 1800 mm, all four sections of the electromagnetic stirring upper roller and the electromagnetic stirring lower roller are turned on, the electromagnetic force direction of all four sections of the electromagnetic stirring upper roller adopts a right-right-left-left mode, and the electromagnetic force direction of all four sections of the electromagnetic stirring lower roller adopts a right-left-left mode. When the slab enters the action interval of the roller, eight reflow zones are formed inside the slab, wherein two reflow zones are formed in the middle area and the rear end area of ​​the slab, and four reflow zones are formed in the front end area of ​​the slab; or, the electromagnetic force direction of all four sections of the electromagnetic stirring upper roller adopts a right-left-left mode, and the electromagnetic force direction of all four sections of the electromagnetic stirring lower roller adopts a left-right-left-left mode. When the slab enters the action interval of the roller, twelve reflow zones are formed inside the slab, wherein four reflow zones are formed in the middle area and the two end areas of the slab; When the cross-sectional size of the slab is greater than 1800mm, all four sections of the electromagnetic stirring upper roller and the electromagnetic stirring lower roller are turned on, the electromagnetic force direction of all four sections of the electromagnetic stirring upper roller adopts a right-right-right-left mode, and the electromagnetic force direction of all four sections of the electromagnetic stirring lower roller adopts a right-left-left-left mode. When the slab enters the action range of the roller, seven reflow zones are formed inside the slab, a reflow zone is formed within 3 / 4 of the left rear end area of ​​the slab, a reflow zone is formed within 1 / 4 of the right rear end area of ​​the slab, a reflow zone is formed within 3 / 4 of the left middle area of ​​the slab, two reflow zones are formed within 1 / 4 of the right middle area of ​​the slab, a reflow zone is formed within 1 / 4 of the left front end area of ​​the slab, and 3 reflow zones are formed in the slab. A reflow zone is formed within the range of 3 / 4 from the right of the front end area of ​​the slab; or, the electromagnetic force directions of all four sections of the electromagnetic stirring upper roller adopt the right-right-right-left mode, and the electromagnetic force directions of all four sections of the electromagnetic stirring lower roller adopt the left-left-left-left mode. When the slab enters the action range of the roller body, six reflow zones are formed inside the slab, a reflow zone is formed within the range of 3 / 4 from the left of the rear end area of ​​the slab, a reflow zone is formed within the range of 1 / 4 from the right of the front end area of ​​the slab, a reflow zone is formed within the range of 3 / 4 from the left of the middle area of ​​the slab, a reflow zone is formed within the range of 1 / 4 from the right of the middle area of ​​the slab, a reflow zone is formed within the range of 3 / 4 from the left of the front end area of ​​the slab, and a reflow zone is formed within the range of 1 / 4 from the right of the front end area of ​​the slab.

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