CN109604551B - An independently adjustable combined electromagnetic braking device and method for controlling the flow of molten steel - Google Patents

Abstract

An independent adjustable combined electromagnetic braking device and method for controlling the flow of molten steel, comprising a mold, wherein a wide surface of the mold is provided with horizontal magnetic poles, and horizontal excitation coils are provided on the outside of the two horizontal magnetic poles, and the mold is provided on the mold. A magnetic yoke is sleeved, the magnetic yoke is corresponding to the horizontal excitation coil, and the inner surface of the magnetic yoke is matched with the outer surface of the horizontal excitation coil and the outer surface of the mold, and a vertical magnetic pole is arranged on the wide surface of the mold above the horizontal magnetic pole. Vertical excitation coils are arranged between the crystallizer and the vertical magnetic poles, and the horizontal magnetic poles are not connected to the vertical magnetic poles. Both sets of vertical magnetic poles are provided with horizontal iron cores or vertical iron cores. One end of the nozzle is connected with the tundish, and the other end extends into the crystallizer. The device of the present invention is composed of a pair of horizontal magnetic poles and two pairs of vertical magnetic poles. The current intensity applied by the excitation coils on the three pairs of magnetic poles can be independently regulated according to the actual flow state of molten steel in the mold.

Description

An independently adjustable combined electromagnetic braking device and method for controlling the flow of molten steel

technical field

The invention belongs to the technical field of continuous casting, and in particular relates to an independently adjustable combined electromagnetic braking device and method for controlling the flow of molten steel.

Background technique

In the continuous casting production process, after the high-temperature molten steel flows out from the side hole of the submerged nozzle, a high-speed jet with a certain angle is formed to impact the narrow surface area of the mold, forming a high-speed upper and lower reflux. The molten steel flowing back up will impact the steel-slag interface in the mold, causing the fluctuation of the steel-slag interface, especially the fluctuation of the steel-slag interface near the meniscus on the side of the mold, which is easy to cause slag entrainment. The molten steel in the lower reflux has a larger penetration depth, and at the same time, the non-metallic inclusions, bubbles and other heterogeneous substances in the molten steel will enter the deeper position of the mold with the molten steel in the lower reflux. Because the heterogeneous material is not easy to float, and may be captured by the front of the molten steel initial solidification shell, resulting in surface or subcutaneous defects of the continuous casting billet.

In addition, the molten steel jet flowing out of the side hole of the submerged nozzle will impact the initial solidification shell in the mold, resulting in thinning or unevenness of the initial solidification shell, which is likely to cause a steel breakout accident.

In order to solve the above problems, technicians usually install an electromagnetic brake in the horizontal direction of the wide face of the mold, and apply a current to the excitation coil on the electromagnetic brake to form a stable magnetic field in the mold. When the molten steel flowing in the mold passes through the steady-state magnetic field, it will be subjected to an electromagnetic force opposite to the flow direction of the molten steel, which will reduce the flow rate of the molten steel in the mold and change the flow state, so that the non-contact method is used to control the flow of the molten steel in the mold. The purpose of molten steel flow.

At present, the electromagnetic braking devices for generating a steady state magnetic field mainly include regional electromagnetic braking devices, full-width one-stage electromagnetic braking devices and full-width two-stage electromagnetic braking devices.

The regional electromagnetic braking device generates a steady-state magnetic field through two pairs of rectangular magnetic poles arranged in the outflow area of the side hole of the mold nozzle to brake the high-speed jet molten steel flowing out of the side hole of the mold nozzle, thereby controlling the mold The role of internal molten steel flow. However, due to the limitation of the size of the magnetic pole, the action area of the steady-state magnetic field generated by it is limited, and it cannot effectively control the flow of molten steel in the entire mold. Channels and other defects reduce its braking effect.

A full-width one-stage electromagnetic braking device (such as the Chinese patent application with the application number 98810685.X) generates a steady-state magnetic field through a pair of horizontal magnetic poles arranged below the submerged nozzle of the mold and covering the entire wide surface of the mold, thereby acting as a The effect of suppressing the flow rate of molten steel jet in the side hole of the submerged nozzle and reducing the impact depth of the molten steel in the lower backflow in the mold. However, limited by the relative position of the horizontal magnetic pole and the action area of the horizontal stationary magnetic field, the full-width one-stage electromagnetic braking device cannot effectively control the flow rate of the molten steel in the upper backflow in the mold, the fluctuation of the steel slag interface and the slag entrainment. Unreasonable magnetic poles The relative position and magnetic induction intensity even cause a negative electromagnetic braking effect, reducing the quality of the continuous casting slab.

The full-width two-stage electromagnetic braking device (for example, the Chinese patent application with the application number of 98801009.7) generates a steady-state magnetic field by arranging the upper and lower pairs of horizontal magnetic poles on the wide surface of the mold, wherein the lower horizontal magnetic pole is located below the immersed nozzle. The effect of suppressing the impact of molten steel jet and the impact depth of the lower reflux molten steel; the upper horizontal magnetic pole is arranged in the surface area of the molten steel of the mold, which plays a role in controlling the fluctuation of the molten steel surface of the mold. Because the full-width two-stage electromagnetic braking device adds a pair of horizontal magnetic poles on the basis of the full-width one-stage electromagnetic braking device, the generated magnetic field can suppress the impact depth of the lower backflow, and can also control the flow rate of the molten steel on the liquid surface of the mold. And the fluctuation of the steel slag interface is controlled, so the braking effect is significantly better than the regional electromagnetic braking and the whole one-stage electromagnetic braking. However, in order to control the fluctuation of the molten steel surface of the mold more effectively, the upper horizontal magnetic pole often needs to generate a sufficiently large magnetic field strength, which will easily cause the molten steel surface flow rate in most areas of the mold to be too low, thus significantly reducing the molten steel. The heat exchange with mold slag is not conducive to the melting of mold slag and the adsorption of inclusions.

In addition, since the positions of the horizontal magnetic poles of the full-width one-stage electromagnetic braking device and the full-width two-stage electromagnetic braking device cannot be adjusted in the height direction, in the continuous casting production process, when the process parameters change, the horizontal magnetic pole and the process parameters are different. The matching relationship will also undergo various changes. If a reasonable and optimal matching relationship cannot always be maintained, the metallurgical effect of the electromagnetic brake will be seriously affected, and it will even be detrimental to the floating of heterogeneous substances such as inclusions and bubbles.

The Chinese Patent No. 200810011104.7 discloses a vertical electromagnetic braking device, which arranges two pairs of vertical magnetic poles along the height direction of the mold in the wide surface area near the narrow surface of the mold, and the vertical magnetic poles generate The steady-state magnetic field can cover both the meniscus area near the narrow surface of the mold and the molten steel jet impact area of the nozzle side hole, which can control the fluctuation of the steel slag interface near the meniscus of the mold and restrain the molten steel jet impact of the nozzle side hole. effect. Since the magnetic field generated by the electromagnetic braking device is arranged along the height direction of the mold, its braking effect is less affected by changes in process parameters such as the insertion depth of the submerged nozzle and the inclination of the nozzle. However, the magnetic field generated by the electromagnetic braking device has a limited coverage width in the mold width direction. When the mold width is large, the magnetic field strength in the center area of the mold width is weak, and the center area of the mold cannot be effectively controlled. The impact depth of the molten steel in the lower reflux is not conducive to the floating of heterogeneous substances such as inclusions and bubbles.

The Chinese patent with the patent number 201610580291.5 also discloses a vertical electromagnetic braking device, which applies two pairs of and The horizontal poles are embedded in the connected vertical core. While the horizontal magnetic pole generates a steady-state magnetic field, a steady-state magnetic field of a certain strength can also be generated between the two pairs of vertical magnetic poles. The electromagnetic braking effect produced by the horizontal steady-state magnetic field is close to that of the full-width one-stage electromagnetic braking device and the full-width two-stage electromagnetic braking device; the electromagnetic braking effect of the steady-state magnetic field formed between the two pairs of vertical magnetic poles is close to that of the vertical electromagnetic braking device. moving device (patent number 200810011104.7). Therefore, under the joint braking action of the vertical magnetic pole and the horizontal magnetic pole, the electromagnetic braking effect is significantly enhanced, and the braking effect is more affected by the process parameters such as the insertion depth of the submerged nozzle, the inclination angle of the nozzle, the height of the liquid level and the drawing speed. Small. However, the vertical magnetic pole and the horizontal magnetic pole of the electromagnetic braking device are embedded connections, and the magnetic field intensity generated between the vertical magnetic poles is limited by the magnetic field intensity of the horizontal magnetic pole. Moreover, the intensity of the magnetic field generated between the vertical magnetic poles is significantly attenuated along the height direction of the mold. When the magnetic field intensity generated by the horizontal magnetic poles is weak, the braking effect of the vertical magnetic poles will be significantly reduced.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the present invention provides an independently adjustable combined electromagnetic braking device for controlling the flow of molten steel, which can preferentially suppress the impact of molten steel flowing out of the nozzle on the side of the mold and control the central area of the lower backflow of the mold. While the molten steel flows, it can suppress the impact of the upper reflux molten steel on the meniscus and the steel slag interface near the narrow surface of the mold, and avoid the impact of the molten steel flow in the lower reflux area being too deep when the flow rate of the molten steel out of the nozzle is too large. And the situation that the molten steel flow rate is too fast in the upper reflux area appears to promote the floating of non-metallic inclusions and argon bubbles and other heterogeneous substances in the central area of the mold, and suppress the fluctuation of the molten steel surface of the mold and the occurrence of slag entrainment. Because the electromagnetic braking device is composed of a pair of horizontal magnetic poles and two pairs of vertical magnetic poles, and the current intensity applied by the vertical magnetic poles and the current intensity applied by the horizontal magnetic poles can be adjusted independently, the magnetic field generated by the vertical magnetic poles can be adjusted independently. And the magnetic field generated by the horizontal magnetic pole can be independently adjusted according to the actual flow of molten steel in the continuous casting mold. Moreover, the metallurgical effect of its electromagnetic braking is less affected by the changes of process parameters and electromagnetic parameters.

In order to achieve the above object, the present invention adopts the following technical solutions:

An independently adjustable combined electromagnetic braking device for controlling the flow of molten steel, comprising a mold, a horizontal magnetic pole, a horizontal excitation coil, a vertical magnetic pole, a horizontal iron core, a surface of the molten steel, a vertical excitation coil, an immersed nozzle, and a magnetic yoke and vertical iron core, the wide surface of the mold is provided with horizontal magnetic poles, the outer sides of the two horizontal magnetic poles are provided with horizontal excitation coils, the mold is sleeved with a magnetic yoke, and the magnetic yokes correspond to the horizontal excitation coils, and The inner surface of the magnetic yoke is matched with the outer surface of the horizontal excitation coil and the outer surface of the mold, a vertical magnetic pole is arranged on the wide surface of the mold above the horizontal magnetic pole, and a vertical magnetic field is arranged between the mold and the vertical magnetic pole. The horizontal magnetic pole is not connected to the vertical magnetic pole. Both sets of vertical magnetic poles are provided with horizontal iron cores or vertical iron cores. One end of the submerged nozzle is connected to the tundish, and the other end extends into the mold.

The cross section of the vertical magnetic pole is set to be rectangular or L-shaped.

The cross section of the vertical magnetic poles is set as a rectangular cross section, a horizontal iron core is arranged on the top or outside of each pair of vertical magnetic poles, and the lower surface of the horizontal iron core is higher than the surface of the molten steel.

The vertical magnetic poles have a rectangular cross section, horizontal iron cores are respectively penetrated between the vertical magnetic poles located on the same wide surface, and the two pairs of vertical magnetic poles are gap-fitted with the horizontal iron cores.

The cross-section of the vertical magnetic poles is set to be an L-shaped section, a vertical iron core is sleeved on each pair of vertical magnetic poles, or a vertical iron core penetrates through each pair of vertical magnetic poles, and the vertical magnetic poles are connected with the vertical iron cores. Clearance fit.

The horizontal magnetic pole is arranged along the length direction of the crystallizer in the lower backflow impact area below the submerged nozzle, and the thickness of the horizontal magnetic pole along the height direction of the crystallizer is 10-500mm.

The height of the vertical magnetic pole is set to cover 200mm above the surface of the molten steel in the mold and extend downward to the upper end area of the horizontal magnetic pole.

The magnetic induction intensity of the steady state magnetic field between the horizontal magnetic poles and the vertical magnetic poles is 0.01-3T.

An independently adjustable combined electromagnetic braking method for controlling the flow of molten steel adopts an independently adjustable combined electromagnetic braking device for controlling the flow of molten steel, comprising the following steps:

Step 1, in the process of high-speed continuous casting, molten steel flows out from the tundish through the side hole of the submerged nozzle, and hits the narrow surface of the mold in the form of a high-speed jet, forming a high-speed upward and downward reflux;

Step 2: After a steady current is applied to the horizontal excitation coil and the vertical excitation coil through an external electromagnetic braking DC power supply, a steady and constant magnetic field is formed between the two pairs of vertical magnetic poles and a pair of horizontal magnetic poles. The stable magnetic field formed between them brakes the flow rate of molten steel in the immersed nozzle jet and the flow rate of molten steel in the upper backflow, thereby stabilizing the fluctuation of the steel slag interface in the mold. The flow rate of the backflow molten steel reduces the penetration depth of the molten steel jet, floats the bubbles and non-metallic inclusions, and removes the floating bubbles and non-metallic inclusions.

The beneficial effects of the present invention are:

1. The independently adjustable combined electromagnetic braking device according to the present invention is composed of a pair of horizontal magnetic poles and two pairs of vertical magnetic poles. The flow state is independently regulated.

2. The present invention uses a combination of a pair of horizontal magnetic poles and two pairs of vertical magnetic poles to generate a steady-state magnetic field. After applying current to the excitation coil, the horizontal magnetic pole located under the submerged nozzle can generate a stable magnetic field covering the entire width of the mold to suppress the impact of the molten steel jet on the narrow surface of the mold and reduce the impact depth of the lower backflow molten steel , to promote the floating removal of non-metallic inclusions and air bubbles; and the magnetic field generated by the two pairs of vertical magnetic poles located above the horizontal magnetic poles can cover the impact point of the molten steel jet, the front area of the initial solidified shell, and the areas near the sides of the mold. The molten steel surface and the molten steel area near the meniscus make the molten steel jet be restrained by the magnetic field before it hits the narrow surface of the mold to solidify the shell, which weakens the impact of the molten steel jet on the narrow surface of the mold and reduces the return flow of molten steel. The impact of the flow rate and the upper backflow molten steel on the slag interface stabilizes the fluctuation of the slag interface in the narrow meniscus area of the mold, reduces the possibility of slag entrainment, and improves the quality of continuous casting slabs.

3. The height requirement of the vertical magnetic pole of the present invention is to cover 200mm above the surface of the molten steel in the mold and extend downward to the area of 1-3mm above the horizontal magnetic pole, that is, the magnetic field generated by the vertical magnetic pole covers the narrow surface jet of the mold. The area between the point of impact and the liquid level on the crystallizer. In the continuous casting production process, even if the process parameters such as the insertion depth of the submerged nozzle, the outflow angle of the nozzle side hole, the liquid level height and the pulling speed are changed, the molten steel flow near the side of the mold is always in the area covered by the vertical magnetic pole. Therefore, the fluctuation of the slag interface near the side of the mold and the impact depth of the molten steel can still be effectively controlled, so that the braking effect is less affected by the changes of the process parameters.

4. The present invention uses a combination of a pair of horizontal magnetic poles and two pairs of vertical magnetic poles to generate a steady-state magnetic field. When the width and thickness of the slab change, the distance between the two pairs of vertical magnetic poles along the width direction of the mold and the The distance of the magnetic poles along the thickness direction of the mold can be changed with the change of the slab size, so as to obtain a good electromagnetic braking effect.

5. In the independently adjustable combined electromagnetic braking device of the present invention, the magnitude of the current flowing between the horizontal magnetic pole and the vertical magnetic pole excitation coil can be independently regulated according to the actual flow of molten steel in the mold, that is, While realizing the suppression of the flow rate of molten steel in the lower backflow in the mold, it can also independently control the flow rate of the molten steel in the upper backflow in the mold, the flow rate of the molten steel at the meniscus and the fluctuation of the steel slag interface, which enhances the electromagnetic braking. Flexibility of effects.

Description of drawings

Fig. 1 is an independent adjustable combined electromagnetic braking device for controlling the flow of molten steel with a horizontal iron core located outside a vertical magnetic pole of the present invention;

Fig. 2 is an independent adjustable combined electromagnetic braking device for controlling the flow of molten steel with a horizontal iron core located at the top of a vertical magnetic pole of the present invention;

3 is an independent adjustable combined electromagnetic braking device for controlling the flow of molten steel with a vertical iron core sleeved on a vertical magnetic pole of the present invention;

4 is an independent adjustable combined electromagnetic braking device for controlling the flow of molten steel with the vertical iron core running through the vertical magnetic pole of the present invention;

5 is an independent adjustable combined electromagnetic braking device for controlling the flow of molten steel with a horizontal iron core running through the vertical magnetic pole on the same side of the present invention;

Figure 6(a) shows that when a current of 200A is applied to the horizontal excitation coil of the horizontal magnetic pole, and a current of 100A is applied to the vertical excitation coil 3 of the vertical magnetic pole in the connection mode of the vertical iron core shown in Figure 3, the thickness center plane of the mold is along the crystallized surface. Magnetic field distribution map in the height direction of the device;

Figure 6(b) shows that when a current of 250A is applied to the horizontal excitation coil of the horizontal magnetic pole and a current of 100A is applied to the vertical excitation coil of the vertical magnetic pole in the vertical iron core connection mode shown in Figure 3, the thickness center plane of the mold is along the mold Magnetic field distribution map in the height direction;

Figure 6(c) shows that in the connection mode of the vertical iron core in Figure 3, when a current of 250A is applied to the horizontal excitation coil of the horizontal magnetic pole, and a current of 200A is applied to the vertical excitation coil of the vertical magnetic pole, the thickness center plane of the mold is along the mold. Magnetic field distribution map in the height direction;

Figure 7(a) is the flow field diagram of the molten steel at the center plane of the thickness of the mold when there is no electromagnetic braking action;

Figure 7(b) is the flow field diagram of the molten steel at the thickness center plane of the mold when the input current of the vertical excitation coil of the vertical magnetic pole and the horizontal excitation coil of the horizontal magnetic pole are both 250A under the connection mode of the vertical iron core of Figure 3;

Figure 8 shows the connection mode of the vertical iron core in Figure 3, when A is without electromagnetic braking, B is the input current of the horizontal excitation coil of the horizontal magnetic pole is 250A, and the input current of the vertical excitation coil of the vertical magnetic pole is 150A and C When the input current of the horizontal excitation coil of the horizontal magnetic pole is 250A, and the input current of the vertical excitation coil of the vertical magnetic pole is 250A, the flow velocity distribution diagram at the surface of the molten steel on the central surface of the mold thickness.

1-Mold, 2-Horizontal magnetic pole, 3-Horizontal excitation coil, 4-Vertical magnetic pole, 5-Horizontal iron core, 6-Steel surface, 7-Vertical excitation coil, 8-Submerged nozzle, 9-Magnetic Yoke, 10-vertical core.

Detailed ways

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

As shown in Figures 1-5, an independently adjustable combined electromagnetic braking device for controlling the flow of molten steel includes a mold 1, a horizontal magnetic pole 2, a horizontal excitation coil 3, a vertical magnetic pole 4, a horizontal iron core 5, a steel Liquid surface 6, vertical excitation coil 7, immersed nozzle 8, magnetic yoke 9 and vertical iron core 10, the wide surface of the mold 1 is provided with horizontal magnetic poles 2, and the stable magnetic field generated between the horizontal magnetic poles 2 is used for In order to suppress the molten metal jet and the flow rate of molten steel in the lower backflow, the outer sides of the two horizontal magnetic poles 2 are provided with a horizontal excitation coil 3, and a magnetic yoke 9 is sleeved on the mold 1, and the magnetic yoke 9 corresponds to the horizontal excitation coil 3. And the inner surface of the yoke 9 is matched with the outer surface of the horizontal excitation coil 3 and the outer surface of the crystallizer 1, and a vertical magnetic pole 4 is arranged on the wide surface of the crystallizer 1 above the horizontal magnetic pole 2. The steady magnetic field is used to suppress the upper reversal flow and the flow rate of molten steel at the meniscus. The magnitude of the input current intensity of the horizontal excitation coil 3 and the vertical excitation coil 7 can be independently regulated according to the molten steel flow state in the mold 1. A vertical excitation coil 7 is arranged between the mold 1 and the vertical magnetic pole 4, and the horizontal magnetic pole 2 is not connected to the vertical magnetic pole 4. The two sets of vertical magnetic poles 4 are provided with a horizontal iron core 5 or a vertical iron core. 10. One end of the submerged nozzle 8 is connected to the tundish, and the other end extends to the inside of the mold 1, and molten steel is transported into the mold 1 through the tundish and the submerged nozzle 8.

The cross section of the vertical magnetic pole 4 is set to be rectangular or L-shaped.

The cross section of the vertical magnetic poles 4 is set as a rectangular section, and a horizontal iron core 5 is disposed on the top or outside of each pair of vertical magnetic poles 4 , and the lower surface of the horizontal iron core 5 is higher than the molten steel surface 6 .

The vertical magnetic poles 4 have a rectangular cross-section. Horizontal iron cores 5 are respectively penetrated between the vertical magnetic poles 4 located on the same wide surface.

The cross section of the vertical magnetic poles 4 is set to be an L-shaped section, and a vertical iron core 10 is sleeved on each pair of vertical magnetic poles 4 or a vertical iron core 10 is penetrated through each pair of vertical magnetic poles 4, and the vertical magnetic poles 4 Clearly fit with the vertical iron core 10 .

The horizontal magnetic pole 2 is disposed along the length direction of the mold 1 in the lower backflow impact area below the submerged nozzle 8 , and the thickness of the horizontal magnetic pole 2 along the height direction of the mold 1 is 10-500 mm.

The height of the vertical magnetic pole 4 is set to cover 200 mm above the molten steel surface 6 in the mold 1 and extend downward to the upper end area of the horizontal magnetic pole 2 .

The magnetic induction intensity of the steady state magnetic field between the horizontal magnetic poles 2 and the vertical magnetic poles 4 is 0.01-3T.

An independently adjustable combined electromagnetic braking method for controlling the flow of molten steel adopts an independently adjustable combined electromagnetic braking device for controlling the flow of molten steel, comprising the following steps:

Step 1, in the process of high-speed continuous casting, the molten steel flows out from the tundish through the side hole of the submerged nozzle 8, and hits the narrow surface of the mold 1 in the form of a high-speed jet, forming a high-speed upward and downward reflux;

Step 2: After a steady current is applied to the horizontal excitation coil 3 and the vertical excitation coil 7 through an external DC power supply, a steady and constant magnetic field is formed between the two pairs of vertical magnetic poles 4 and a pair of horizontal magnetic poles 2. The stable and constant magnetic field formed between the magnetic poles 4 brakes the flow rate of the molten steel jet in the submerged nozzle 8 and the flow rate of the molten steel in the upper backflow, thereby stabilizing the fluctuation of the steel slag interface in the mold 1. The magnetic field is used to brake the flow rate of the refluxing molten steel, reduce the penetration depth of the molten steel jet, make the bubbles and non-metallic inclusions float, and remove the floating bubbles and non-metallic inclusions.

Example 1

This embodiment adopts the independently adjustable combined electromagnetic braking device as shown in FIG. 3 . In this embodiment, the vertical iron core 10 is sleeved on the vertical magnetic pole 4 , and the vertical magnetic pole 4 can move along the width direction of the mold 1 . The thickness of the horizontal magnetic pole 2 along the height direction of the mold 1 is 150mm, the cross-sectional size of the mold 1 is 1200mm×200mm, the height of the vertical magnetic pole 4 is 420mm, and the electromagnetic braking DC power supply is 0-4000A, changing the current intensity The magnetic field distribution diagram of the thickness center plane of the lower mold 1 along the height direction of the mold 1 .

An independently adjustable combined electromagnetic braking method for controlling the flow of molten steel adopts an independently adjustable combined electromagnetic braking device for controlling the flow of molten steel, comprising the following steps:

Step 1, in the process of high-speed continuous casting, the molten steel flows out from the tundish through the side hole of the submerged nozzle 8, and hits the narrow surface of the mold 1 in the form of a high-speed jet, forming a high-speed upward and downward reflux;

Step 2, apply a constant current to the horizontal excitation coil 3 through a 200A external electromagnetic braking DC power supply, and at the same time apply a constant current to the vertical excitation coil 7 through a 100A external electromagnetic braking DC power supply. A steady and constant magnetic field is formed between the horizontal magnetic poles 2, and the steady and constant magnetic field formed between the two pairs of vertical magnetic poles 4 brakes the flow rate of the molten steel jet of the submerged nozzle 8 and the flow rate of the molten steel in the upper backflow, thereby stabilizing the steel slag in the mold 1. The interface fluctuates, and at the same time, the steady magnetic field formed between a pair of horizontal magnetic poles 2 brakes the flow rate of the molten steel in the backflow, reduces the penetration depth of the molten steel jet, floats bubbles and non-metallic inclusions, and removes the floating bubbles and non-metallic inclusions; adjust the current of the horizontal excitation coil 3 to 250A, and the current of the vertical excitation coil 7 to 100A, repeat step 2; adjust the current of the vertical excitation coil 7 to 200A, and the horizontal excitation The current passing through coil 3 is 250A unchanged, and step 2 is repeated.

It can be seen from Figures 6(a), 6(b) and 6(c) that when the independently adjustable combined electromagnetic brake is applied, a stable and uniform magnetic field can be generated in the coverage area of the vertical magnetic pole 4 and the horizontal magnetic pole 2. As the current intensity of the vertical excitation coil 7 of the vertical magnetic poles 4 increases, the magnetic induction intensity generated between the vertical magnetic poles 4 gradually increases. Since the input current intensity of the vertical excitation coil 7 of the vertical magnetic pole 4 and the horizontal excitation coil 3 of the horizontal magnetic pole 2 can be independently adjusted according to the flow of molten steel in the mold 1, the flow of molten steel in the mold 1 is controlled. more flexibility.

Example 2

This embodiment adopts the independently adjustable combined electromagnetic braking device as shown in FIG. 3 . In this embodiment, the vertical iron core 10 is sleeved on the vertical magnetic pole 4 , and the vertical magnetic pole 4 can move along the width direction of the mold 1 . , the thickness of the horizontal magnetic pole 2 along the height direction of the mold 1 is 150 mm, the cross-sectional size of the mold 1 is 1200 mm × 200 mm, the height of the vertical magnetic pole 4 is 420 mm, the inclination angle of the side hole of the submerged nozzle 8 is -15°, and the immersion The immersion depth of the nozzle 8 is 210mm, the drawing speed is 1.8m/min, the electromagnetic braking DC power supply is 0-4000A, and the molten steel flow field distribution at the thickness center plane of the mold 1 under the condition of with and without electromagnetic braking .

An independently adjustable combined electromagnetic braking method for controlling the flow of molten steel adopts an independently adjustable combined electromagnetic braking device for controlling the flow of molten steel, comprising the following steps:

Step 1, in the process of high-speed continuous casting, the molten steel flows out from the tundish through the side hole of the submerged nozzle 8, and hits the narrow surface of the mold 1 in the form of a high-speed jet, forming a high-speed upward and downward reflux;

Step 2: A steady current is applied to the horizontal excitation coil 3 and the vertical excitation coil 7 through a 250A external electromagnetic braking DC power supply, respectively, to form a steady and constant magnetic field between the two pairs of vertical magnetic poles 4 and a pair of horizontal magnetic poles 2. The stable magnetic field formed between the opposite vertical magnetic poles 4 brakes the flow rate of molten steel in the immersion nozzle 8 and the flow rate of the molten steel in the upper backflow, thereby stabilizing the fluctuation of the steel slag interface in the mold 1. The steady magnetic field is used to brake the flow rate of the backflow molten steel, reduce the penetration depth of the molten steel jet, float the bubbles and non-metallic inclusions, and remove the floating bubbles and non-metallic inclusions.

It can be seen from Figure 7(a) that when the magnetic field is not applied, the molten steel flowing out from the side hole of the submerged nozzle 8 hits the narrow surface of the mold 1 at a high speed, forming a lower and upper reflux with a high speed. At this time, the surface of the molten steel 6 The flow rate is relatively large, which is not conducive to the stability of the fluctuation of the steel slag interface; it can be seen from Fig. 7(b) that after applying the independent adjustable combined electromagnetic brake, the flow rate of the molten steel in the lower and upper reflux is significantly reduced. At this time, the surface of the molten steel is 6 The flow velocity is small, which is conducive to stabilizing the fluctuation of the slag interface. Therefore, the independently adjustable combined electromagnetic braking device of the present invention can suppress the impact of the molten steel jet on the narrow surface of the mold 1 and the flow rate of the lower backflow, and at the same time can effectively suppress the flow rate of the upper backflow near the narrow surface of the mold 1, which is beneficial to the steel slag interface. The stability of fluctuations prevents slag rolls.

Example 3

This embodiment adopts the independently adjustable combined electromagnetic braking device as shown in FIG. 3 . In this embodiment, the vertical iron core 10 is sleeved on the vertical magnetic pole 4 , and the vertical magnetic pole 4 can move along the width direction of the mold 1 . , the thickness of the horizontal magnetic pole 2 along the height direction of the mold 1 is 150 mm, the cross-sectional size of the mold 1 is 1200 mm × 200 mm, the height of the vertical magnetic pole 4 is 420 mm, the inclination angle of the side hole of the submerged nozzle 8 is -15°, and the immersion The immersion depth of the nozzle 8 is 210mm, the drawing speed is 1.8m/min, the electromagnetic braking DC power supply is 0-4000A, with or without electromagnetic braking and changing the thickness of the molten steel on the center surface of the mold 1 under the DC power supply Flow velocity profile at surface 6.

An independently adjustable combined electromagnetic braking method for controlling the flow of molten steel adopts an independently adjustable combined electromagnetic braking device for controlling the flow of molten steel, comprising the following steps:

Step 1, in the process of high-speed continuous casting, the molten steel flows out from the tundish through the side hole of the submerged nozzle 8, and hits the narrow surface of the mold 1 in the form of a high-speed jet, forming a high-speed upward and downward reflux;

Step 2, apply a constant current to the horizontal excitation coil 3 through a 250A external electromagnetic braking DC power supply, and at the same time apply a constant current to the vertical excitation coil 7 through a 150A external electromagnetic braking DC power supply. A steady and constant magnetic field is formed between the horizontal magnetic poles 2, and the steady and constant magnetic field formed between the two pairs of vertical magnetic poles 4 brakes the flow rate of the molten steel jet of the submerged nozzle 8 and the flow rate of the molten steel in the upper backflow, thereby stabilizing the steel slag in the mold 1. The fluctuation of the interface, at the same time, through the stable magnetic field formed between a pair of horizontal magnetic poles 2 to brake the flow rate of the molten steel in the downflow, reduce the penetration depth of the molten steel jet, make the bubbles and non-metallic inclusions float, and remove the floating molten steel. Air bubbles and non-metallic inclusions; adjust the current of the vertical excitation coil 7 to 250A, and the current of the horizontal excitation coil 3 to be 250A unchanged, and repeat step 2.

It can be seen from Fig. 8 that under the condition that no electromagnetic braking is applied, the upper backflow formed by the molten steel jet hitting the narrow surface of the mold 1 impacts the molten steel surface 6 at a high speed, and at this time, the maximum velocity of the molten steel surface 6 reaches 0.226m/s; After applying the independent adjustable combined electromagnetic brake, the current intensity applied by the vertical excitation coil 7 is 150A, and the current intensity applied by the horizontal excitation coil 3 is 250A. Under the combined action of the vertical distributed magnetic field and the horizontal distributed magnetic field, the flow rate of the molten steel surface 6 The maximum value is reduced from 0.226m/s to 0.161m/s, a decrease of 29%; when the current intensity applied by the vertical excitation coil 7 continues to increase to 250A, the magnetic induction intensity generated by it continues to increase. The inhibitory effect of the liquid is further enhanced, and the maximum velocity of the liquid steel surface 6 is reduced to 0.03 m/s, which is 87% lower than that without electromagnetic braking.

Claims (3)

1. An independent adjustable combined electromagnetic braking device for controlling the flow of molten steel is characterized by comprising a crystallizer, a horizontal magnetic pole, a horizontal excitation coil, a vertical magnetic pole, a horizontal iron core, a molten steel surface, a vertical excitation coil, an immersion type water gap, a magnetic yoke and a vertical iron core, wherein the horizontal magnetic pole is arranged on the wide surface of the crystallizer, the horizontal excitation coil is arranged on the outer sides of the two horizontal magnetic poles, the magnetic yoke is sleeved on the crystallizer and corresponds to the horizontal excitation coil, the inner surface of the magnetic yoke is in clearance fit with the outer surface of the horizontal excitation coil and the outer surface of the crystallizer, the vertical magnetic pole is arranged on the wide surface of the crystallizer above the horizontal magnetic pole, the vertical excitation coil is arranged between the crystallizer and the vertical magnetic pole, the horizontal magnetic pole is not connected with the vertical magnetic pole, the horizontal iron core, the other end extends into the crystallizer;

the cross section of the vertical magnetic pole is rectangular or L-shaped; when the cross section of the vertical magnetic poles is set to be a rectangular cross section, a horizontal iron core is arranged on the top or the outer side of each pair of vertical magnetic poles, the lower surface of each horizontal iron core is higher than the surface of molten steel, or the horizontal iron cores penetrate through the vertical magnetic poles on the same wide surface respectively, and the two pairs of vertical magnetic poles are in clearance fit with the horizontal iron cores; the cross section of the vertical magnetic pole is set to be an L-shaped cross section, a vertical iron core is sleeved on each pair of vertical magnetic poles or penetrates through each pair of vertical magnetic poles, and the vertical magnetic poles are in clearance fit with the vertical iron cores;

the horizontal magnetic pole is arranged in a lower backflow impact area below the submerged nozzle along the length direction of the crystallizer, and the thickness of the horizontal magnetic pole along the height direction of the crystallizer is 10-500 mm;

the height of the vertical magnetic pole is set to cover 200mm from the upper part of the surface of molten steel in the crystallizer and extend downwards to the upper end area of the horizontal magnetic pole.

2. The independently adjustable combined electromagnetic brake device for controlling the flow of molten steel according to claim 1, wherein: the magnetic induction intensity of the steady magnetic field between the horizontal magnetic poles and the vertical magnetic poles is 0.01-3T.

3. The method for controlling the independently adjustable combined electromagnetic brake of the flowing of the molten steel adopts the independently adjustable combined electromagnetic brake device for controlling the flowing of the molten steel, which is characterized by comprising the following steps:

step 1, in the process of high-casting speed continuous casting, molten steel flows out from a tundish through a side hole of an immersion nozzle and impacts a narrow surface of a crystallizer in a high-speed jet form to form ascending reflux and descending reflux with high speed;

and 2, after applying constant current to the horizontal magnet exciting coil and the vertical magnet exciting coil respectively through an external electromagnetic braking direct-current power supply, forming a constant magnetic field between the two pairs of vertical magnetic poles and the pair of horizontal magnetic poles, braking the flow velocity of the jet molten steel of the submerged nozzle and the flow velocity of the upward-flowing molten steel through the constant magnetic field formed between the two pairs of vertical magnetic poles, further stabilizing the fluctuation of a steel slag interface in the crystallizer, braking the flow velocity of the downward-flowing molten steel through the constant magnetic field formed between the pair of horizontal magnetic poles, reducing the penetration depth of the molten steel jet flow, floating bubbles and nonmetallic inclusions, and removing the floating bubbles and nonmetallic inclusions.

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