A hybrid electromagnetic field stirring device and working method

Abstract

A hybrid electromagnetic stirring device and working method. A hybrid electromagnetic stirring device comprises a crystallizer, wherein a plurality of salient poles I are arranged at intervals on the outer circumference of the crystallizer, an iron core is sleeved on the outside of the crystallizer, a plurality of salient poles II are arranged at intervals on the inner circumference of the iron core, and a permanent magnet and a coil group are installed on each salient pole II; the iron core is formed by stacking magnetic conductive materials; the magnetization directions of adjacent permanent magnets are opposite; the number of salient poles II is greater than the number of salient poles I; the winding direction of the coil group at salient pole II is parallel to the flow direction of non-ferrous metal in the crystallizer; an air gap is left between the salient poles I and II. A rotating magnetic field is generated inside the non-ferrous metal liquid in the crystallizer, which can fully stir the non-ferrous metal liquid and significantly improve the quality of non-ferrous metal ingot products.

Description

Technical Field

[0001] The invention relates to the technical field of steel continuous casting, and in particular to a mixed electromagnetic stirring device and a working method. Background Art

[0002] Environmental protection and safety are two aspects that attract much attention in the nonferrous smelting process. Improper handling will pollute the environment and threaten the personal safety of operators. Electromagnetic stirrers are now used in the steel industry to effectively improve product output and quality.

[0003] Taking rotary electromagnetic stirring as an example, the theory of electromagnetic stirring is that an alternating magnetic field is generated after an alternating current is passed through. When the alternating magnetic field passes through the non-ferrous metal liquid, an induced electromotive force is induced, thereby generating an induced current. The electromagnetic force finally generated in the molten steel is the result of the combined action of the induced current and the electromagnetic field. The generated electromagnetic force can be decomposed into normal electromagnetic force and tangential electromagnetic force. Electromagnetic stirring achieves the stirring of non-ferrous metal liquid under low frequency, which is mainly manifested as tangential force. It is this force that can cause the non-ferrous metal liquid to move in a circular direction.

[0004] However, the electromagnetic force generated by the conventional structure stirrer is mainly determined by the induced current and the magnetic field. The induced current increases with the increase of frequency, while the magnetic field strength decreases with the increase of frequency. Therefore, how to solve the mutual restriction relationship between the induced current, frequency and magnetic field strength to optimize the electromagnetic stirring effect has always been a research hotspot in electromagnetic stirring technology.

[0005] At present, most of the crystallizer electromagnetic stirrers in industrial continuous casting production are conventional cylindrical electromagnetic stirrers, which generate a rotating magnetic field to stir the molten steel horizontally. However, due to the circular inner surface of the crystallizer, the skin effect and eddy current effect of the non-ferrous metal liquid under the action of the magnetic field are obvious, resulting in unsatisfactory stirring effect in the middle area of ​​the non-ferrous metal liquid, poor uniformity of temperature distribution of the non-ferrous metal liquid in the crystallizer, which is not conducive to the increase of the equiaxed crystal rate. At the same time, the longitudinal fluidity of the non-ferrous metal liquid in the crystallizer is poor, resulting in the existence of shrinkage holes and low equiaxed crystal rate in the steel billet. This is the shortcoming of the prior art. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a hybrid electromagnetic stirring device and a working method to address the deficiencies in the prior art, so that a rotating magnetic field is generated inside the non-ferrous metal liquid in the crystallizer, which can fully stir the non-ferrous metal liquid and significantly improve the quality of the non-ferrous metal ingot product.

[0007] This solution is achieved through the following technical measures: a hybrid electromagnetic stirring device, including a crystallizer, a plurality of salient poles I are arranged at intervals on the outer circumference of the crystallizer, an iron core is sleeved on the outside of the crystallizer, a plurality of salient poles II are arranged at intervals on the inner circumference of the iron core, and a permanent magnet and a coil group are installed on each salient pole II; the iron core is formed by stacking magnetic conductive materials; the magnetization directions of adjacent permanent magnets are opposite; the number of salient poles II is greater than the number of salient poles I; the winding direction of the coil group on salient pole II is parallel to the flow direction of non-ferrous metal in the crystallizer; an air gap is left between the salient poles I and II.

[0008] Preferably, the magnetic conductive material is silicon steel sheet, and an annular magnetic insulation and heat conductive layer is provided inside the iron core.

[0009] Preferably, a permanent magnet is installed inside the salient pole II, and the permanent magnet is a rectangular permanent magnet.

[0010] Preferably, the coil group includes multiple turns of DC coils and multiple turns of AC coils, the DC coils in the coil group on the salient pole II are connected in sequence to form a DC magnetic field winding, and the AC coils in the coil group on the salient pole II are connected in sequence to form an AC magnetic field winding.

[0011] Preferably, the number of salient poles II is 12, and the number of salient poles I is 10.

[0012] Preferably, in a clockwise direction, the 12 salient poles II are sequentially provided with coil groups A1, coil group B1, coil group C1, coil group A2, coil group B2, coil group C2, coil group A3, coil group B3, coil group C3, coil group A4, coil group B4, and C4; coil group A1, coil group A2, coil group A3, and coil group A4 are sequentially connected in series to form an A-phase winding, coil group B1, coil group B2, coil group B3, and coil group B4 are sequentially connected in series to form a B-phase winding, and coil group C1, coil group C2, coil group C3, and coil group C4 are sequentially connected in series to form a C-phase winding.

[0013] Preferably, the number of the salient poles II is 6, and the number of the salient poles I is 5.

[0014] Preferably, in a clockwise direction, coil group A1, coil group B1, coil group C1, coil group A2, coil group B2, and coil group C2 are sequentially arranged on the six salient poles II; coil group A1 and coil group A2 are connected in series to form an A-phase winding, coil group B1 and coil group B2 are connected in series to form a B-phase winding, and coil group C1 and coil group C2 are connected in series to form a C-phase winding.

[0015] A working method of a hybrid electromagnetic stirring device, during normal stirring, low-frequency alternating current is introduced into the alternating current magnetic field winding on the salient pole II, and a direct current magnetic field is generated in the direct current magnetic field winding on the salient pole II; under the combined action of the alternating current magnetic field and the permanent magnetic field formed by the permanent magnet installed in the salient pole II, eddy currents are formed in the non-ferrous metal liquid in the crystallizer and electromagnetic force is generated, forcing the non-ferrous metal liquid to rotate and flow.

[0016] Preferably, the rotation direction of the AC magnetic field is determined by the phase sequence of the three-phase AC power supply, and the magnitude and direction of the DC magnetic field are adjusted by changing the magnitude and direction of the DC power.

[0017] The above technical solution has the following technical effects:

[0018] (1) The conventional crystallizer is cylindrical. The crystallizer of the present invention is provided with an outer salient pole (salient pole I) structure, which forms a double salient pole structure with the salient pole II of the iron core, which is beneficial to the skin effect and eddy current effect generated by the magnetic field of the iron core between the non-ferrous metal liquid in the crystallizer, thereby achieving a better longitudinal stirring effect. In addition, since the crystallizer is provided with an outer salient pole (salient pole I) structure, the heat dissipation area of ​​the outer surface of the crystallizer is increased, which can reduce the segregation of the ingot during the stirring process.

[0019] (2) By using AC current and permanent magnets for mixed excitation, the AC current passed through the AC coil winding can be smaller while achieving the same electromagnetic stirring force, thus achieving significant energy-saving effects.

[0020] (3) The electromagnetic force is mainly determined by the induced current and the magnetic field. The induced current increases with the increase of frequency, while the magnetic field strength decreases with the increase of frequency. Using a mixed magnetic field for excitation can solve the restrictive relationship between frequency changes on the induced current and magnetic field strength.

[0021] It can be seen that compared with the prior art, the present invention has outstanding substantive features and significant progress, and the beneficial effects of its implementation are also obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a hybrid electromagnetic field stirring device;

[0023] Figure 2 This is the connection diagram of phase A winding.

[0024] Among them: 1-iron core, 2-magnetic insulation and thermal conductive layer, 3-coil group, 4-permanent magnet, 5-salient pole II, 6-crystallizer, 7-salient pole I. DETAILED DESCRIPTION

[0025] In order to clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods and in conjunction with the accompanying drawings.

[0026] Example 1

[0027] like Figure 1-2 As shown, a hybrid electromagnetic stirring device comprises a crystallizer 6, on the outer circumference of which a plurality of salient poles I7 are arranged at intervals, an iron core 1 is sleeved on the outside of the crystallizer 6, on the inner circumference of which a plurality of salient poles II5 are arranged at intervals, and a permanent magnet 4 and a coil group 3 are mounted on each salient pole II5; the iron core 1 is formed by stacking magnetic conductive materials; the magnetizing directions of adjacent permanent magnets 4 are opposite; the number of salient poles II5 is greater than the number of salient poles I7; the winding direction of the coil group 3 on the salient pole II5 is parallel to the flow direction of non-ferrous metal in the crystallizer 6; an air gap is left between the salient pole I7 and the salient pole II5.

[0028] Furthermore, the magnetic conductive material is silicon steel sheet, and an annular magnetic insulation and heat conductive layer 2 is arranged inside the iron core 1.

[0029] Furthermore, a permanent magnet 4 is installed inside the salient pole II 5, and the permanent magnet 4 is a rectangular permanent magnet.

[0030] Furthermore, the coil group 3 includes multiple turns of DC coils and multiple turns of AC coils. The DC coils in the coil group 3 on the salient pole II5 are connected in sequence to form a DC magnetic field winding, and the AC coils in the coil group on the salient pole II5 are connected in sequence to form an AC magnetic field winding.

[0031] Furthermore, the number of the salient poles II5 is 12, and the number of the salient poles I7 is 10.

[0032] Further, in a clockwise direction, the 12 salient poles II5 are sequentially provided with coil groups A1, coil group B1, coil group C1, coil group A2, coil group B2, coil group C2, coil group A3, coil group B3, coil group C3, coil group A4, coil group B4, and C4; coil group A1, coil group A2, coil group A3, and coil group A4 are sequentially connected in series to form an A-phase winding, coil group B1, coil group B2, coil group B3, and coil group B4 are sequentially connected in series to form a B-phase winding, and coil group C1, coil group C2, coil group C3, and coil group C4 are sequentially connected in series to form a C-phase winding.

[0033] When low-frequency alternating current is passed through the AC winding, a constantly changing alternating magnetic field will be generated inside the iron core and the crystallizer liquid. When the alternating magnetic field passes through the non-ferrous metal liquid, an induced electromotive force will be induced, thereby generating an induced current. The induced current is acted upon by a force in the changing magnetic field, generating an electromagnetic force in the non-ferrous metal liquid. Electromagnetic stirring is the stirring of the non-ferrous metal liquid under low-frequency action, which is mainly manifested as a tangential force. It is this tangential force that can cause the non-ferrous metal liquid to move in a circular direction.

[0034] During normal stirring, low-frequency alternating current is passed through the AC magnetic field winding installed on salient pole II 5. At this time, under the combined action of the magnetic field generated by the alternating current and the permanent magnetic field formed by the permanent magnet 4 installed in salient pole II 5, eddy currents and electromagnetic force will be generated in the non-ferrous metal liquid in the crystallizer 6, forcing the non-ferrous metal liquid to rotate and flow. Since salient pole I 7 is provided on the outer circumference of the crystallizer 6, the magnetic lines of force between the iron core 1 and the rotating non-ferrous metal liquid will change alternately.

[0035] Example 2

[0036] The number of the salient poles II5 is 6, and the number of the salient poles I7 is 5. In clockwise direction, the six salient poles II5 are sequentially provided with coil groups A1, coil groups B1, coil groups C1, coil groups A2, coil groups B2, and coil groups C2; coil groups A1 and coil groups A2 are connected in series to form an A-phase winding, coil groups B1 and coil groups B2 are connected in series to form a B-phase winding, and coil groups C1 and coil groups C2 are connected in series to form a C-phase winding.

[0037] Technical features not described in the present invention can be achieved by or by using existing technologies and will not be described in detail herein. Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above implementation modes. Changes, modifications, additions or substitutions made by ordinary technicians in this field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A hybrid electromagnetic stirring device, characterized in that: It comprises a crystallizer, wherein a plurality of salient poles I are arranged at intervals on the outer circumference of the crystallizer, an iron core is sleeved on the outside of the crystallizer, a plurality of salient poles II are arranged at intervals on the inner circumference of the iron core, and a permanent magnet and a coil group are installed on each salient pole II; the iron core is formed by stacking magnetic conductive materials; the magnetization directions of adjacent permanent magnets are opposite; the number of salient poles II is greater than the number of salient poles I; the winding direction of the coil group on the salient pole II is parallel to the flow direction of the non-ferrous metal in the crystallizer; an air gap is left between the salient poles I and II; The coil group includes multiple turns of DC coils and multiple turns of AC coils. The DC coils in the coil group on the salient pole II are connected in sequence to form a DC magnetic field winding, and the AC coils in the coil group on the salient pole II are connected in sequence to form an AC magnetic field winding.

2. The hybrid electromagnetic stirring device according to claim 1, characterized in that: The magnetic conductive material is silicon steel sheet, and an annular magnetic insulation and heat conductive layer is arranged inside the iron core.

3. The hybrid electromagnetic stirring device according to claim 1, characterized in that: A permanent magnet is installed inside the salient pole II, and the permanent magnet is a rectangular permanent magnet.

4. The hybrid electromagnetic stirring device according to claim 1, characterized in that: The number of the salient poles II is 12, and the number of the salient poles I is 10.

5. The hybrid electromagnetic stirring device according to claim 4, characterized in that: In clockwise direction, coil group A1, coil group B1, coil group C1, coil group A2, coil group B2, coil group C2, coil group A3, coil group B3, coil group C3, coil group A4, coil group B4, and C4 coil groups are sequentially arranged on the 12 salient poles II; coil group A1, coil group A2, coil group A3, and coil group A4 are sequentially connected in series to form an A-phase winding, coil group B1, coil group B2, coil group B3, and coil group B4 are sequentially connected in series to form a B-phase winding, and coil group C1, coil group C2, coil group C3, and coil group C4 are sequentially connected in series to form a C-phase winding.

6. The hybrid electromagnetic stirring device according to claim 1, characterized in that: The number of the salient poles II is 6, and the number of the salient poles I is 5.

7. The hybrid electromagnetic stirring device according to claim 6, characterized in that: In clockwise direction, coil group A1, coil group B1, coil group C1, coil group A2, coil group B2, and coil group C2 are arranged in sequence on the six salient poles II; coil group A1 and coil group A2 are connected in series to form an A-phase winding, coil group B1 and coil group B2 are connected in series to form a B-phase winding, and coil group C1 and coil group C2 are connected in series to form a C-phase winding.

8. A working method using the hybrid electromagnetic stirring device according to any one of claims 1 to 7, characterized in that: During normal stirring, low-frequency AC current is passed through the AC magnetic field winding on salient pole II, and a DC magnetic field is generated in the DC magnetic field winding on salient pole II by the DC current; under the combined action of the AC magnetic field generated by the AC current and the permanent magnetic field formed by the permanent magnet installed in salient pole II, eddy currents are formed in the non-ferrous metal liquid in the crystallizer and electromagnetic force is generated, forcing the non-ferrous metal liquid to rotate and flow.

9. The working method of the hybrid electromagnetic stirring device according to claim 8, characterized in that: The rotation direction of the AC magnetic field is determined by the phase sequence of the three-phase AC power supply, and the magnitude and direction of the DC magnetic field are adjusted by changing the magnitude and direction of the DC power.

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