Composite stirrer and control method thereof

Abstract

The invention relates to the technical field of continuous casting electromagnetic stirring, in particular to a composite stirrer and a control method thereof.The control method comprises the steps that the stirring action mode of an electromagnetic stirring area is determined according to the sequence of sensors for composite electromagnetic stirring and the installation position of the composite stirrer; the liquid level fluctuation index of the molten steel is determined based on the fluctuation amplitude component and the frequency component of the molten steel, the working condition risk of molten steel composite stirring is determined in combination with the pulling speed of a continuous casting machine, and the alternating mode of composite electromagnetic stirring is determined; the tundish superheat degree of the molten steel is obtained, a molten steel solidification state evaluation index is determined, the solidification state of the molten steel is determined based on the molten steel solidification state evaluation index, and the stirring strength is adjusted in response to the solidification state in combination with the molten steel solidification state evaluation index and the alternating mode; and in response to the solidification state of the molten steel in combination with the development trend of molten steel composite stirring and the segregation risk of the molten steel, determining the adjustment measures of the alternating parameters of the alternating mode. The quality of the casting blank is controlled by adjusting the magnetic field form and the stirring mode thereof.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic stirring technology for continuous casting, and in particular to a composite stirrer and its control method. Background Technology

[0002] Electromagnetic stirring technology plays a crucial role in improving the equiaxed grain ratio of continuously cast billets, refining the solidification structure, reducing billet segregation, improving inclusion distribution, and promoting compositional homogenization. The working principle of electromagnetic stirring is that the alternating magnetic field excited by electromagnetic stirring penetrates into the molten steel. The induced current interacts with the magnetic field in the molten steel to generate an electromagnetic force, thereby propelling the molten steel. Therefore, based on the form of the magnetic field excited by electromagnetic stirring, it can be classified into: DC magnetic field, rotating magnetic field, traveling wave magnetic field, and spiral magnetic field electromagnetic stirring, etc.

[0003] Currently, the electromagnetic stirring magnetic fields used in the market are limited to a single type, primarily rotating magnetic fields. In recent years, the demand for high-efficiency continuous casting has led to varying degrees of quality problems in special steels at high casting speeds, such as central porosity, shrinkage cavities, and segregation. While conventional rotating magnetic field electromagnetic stirring can partially improve these quality problems through optimized installation location and operating parameters, it cannot completely solve them. The main reason is that rotating stirring can only achieve strong two-dimensional stirring on the cross-section of the billet, and the electromagnetic force is mainly concentrated near the surface of the billet, making it difficult to penetrate into the core. Therefore, under the action of rotating stirring, the molten steel in the core of the billet is essentially not stirred, and the solute elements and heat in the core cannot be exchanged, thus failing to solve the internal quality problems of the billet. In some cases, excessive stirring can even cause a bright white band of negative solute element segregation to appear in one-quarter of the billet.

[0004] Existing technologies have proposed using composite stirring technology to address billet quality issues. Two technical approaches exist: one is a composite electromagnetic stirrer with multiple magnetic field types and stirring functions. While this type of stirrer offers various magnetic field types and stirring functions, it can only output one magnetic field type during operation. For example, patent CN101700477B incorporates both rotating and traveling wave magnetic fields, but the excitation coil of the rotating magnetic field is placed before or after the excitation coil of the traveling wave magnetic field. In practice, the coil at the front end magnetically shields the magnetic field of the coil at the rear end, resulting in low stirring efficiency. The other approach combines traveling wave and rotating magnetic fields vertically. For instance, patent CN 109158563 B discloses an electromagnetic stirrer for continuous casting molds with a composite magnetic field, where the traveling wave magnetic field generator is placed above the rotating magnetic field generator. This approach utilizes the traveling wave magnetic field to promote the rise of inclusions and bubbles within the continuous casting mold, reducing the impact depth of the molten steel. Additionally, rotating stirring improves the equiaxed crystal ratio of the billet. This composite electromagnetic stirrer is installed in the continuous casting mold area to obtain high-quality, clean steel. However, this solution still cannot solve quality problems such as porosity, shrinkage cavities, and segregation in the core of the billet. Summary of the Invention

[0005] Therefore, the present invention provides a composite agitator and its control method to overcome the problems of porosity, shrinkage cavities and segregation in the core center of the cast billet in the prior art.

[0006] To achieve the above objectives, the present invention provides a control method for a composite stirrer, comprising:

[0007] The stirring mode of the electromagnetic stirring zone is determined by the sequence of the sensors in the composite electromagnetic stirrer and the installation position of the composite stirrer.

[0008] The surface fluctuation index of molten steel is determined based on the amplitude and frequency components of the molten steel fluctuation. The working risk of the composite stirring of molten steel is determined in combination with the casting speed of the continuous casting machine, and the alternation mode of composite electromagnetic stirring is determined.

[0009] The superheat of the tundish is obtained to determine the solidification state evaluation index of the molten steel. Based on the solidification state evaluation index, the solidification state of the molten steel is determined. The stirring intensity is adjusted in response to the solidification state, combined with the solidification state evaluation index and the alternating mode.

[0010] Determine the characteristic value of the change in the solidification state assessment index of molten steel, and determine the development trend of composite stirring of molten steel based on the characteristic value of the change;

[0011] Real-time segregation risk values ​​are obtained based on the casting speed of the continuous casting machine to determine the segregation risk of molten steel.

[0012] In response to the solidification state of molten steel, combined with the development trend of composite stirring of molten steel and the risk of segregation of molten steel, adjustment measures for the alternation parameters of the alternation mode are determined.

[0013] The alternation parameters of the alternation mode include the traveling wave alternation frequency and the rotational alternation frequency.

[0014] Furthermore, the process of determining the stirring action mode of the electromagnetic stirring zone includes:

[0015] The second stirring zone is a fixed spiral magnetic field stirring zone. The first and third stirring zones adopt different stirring modes according to the order of the composite electromagnetic stirring inductors and their different installation positions on the continuous casting machine.

[0016] When the composite electromagnetic stirrer is installed in the continuous casting crystallizer area, the first stirring zone is a multi-dimensional magnetic field stirring zone, and the third stirring zone is a traveling wave magnetic field stirring zone.

[0017] When the composite electromagnetic stirrer is installed in the secondary cooling zone and the solidification end of the continuous casting process, the first stirring zone is a traveling wave magnetic field stirring zone, and the third stirring zone is a rotating magnetic field stirring zone.

[0018] Furthermore, the surface fluctuation index of molten steel in the continuous casting crystallizer zone is calculated by comprehensively considering the fluctuation amplitude and frequency.

[0019] When the liquid level fluctuation index is greater than the first fluctuation index, the second alternation mode is determined to be adopted, and the second sensor rotates alternately.

[0020] When the liquid level fluctuation index is less than or equal to the second fluctuation index, the first alternation mode is determined to be adopted;

[0021] When the liquid level fluctuation index is less than or equal to the first fluctuation index and greater than the second fluctuation index, the risk condition of combined stirring of molten steel is judged based on the casting speed of the continuous casting machine.

[0022] Furthermore, the process of determining the risk conditions of combined stirring of molten steel includes:

[0023] The casting speed of the continuous casting machine is obtained, and when the casting speed is less than the preset speed, it is determined that the casting speed of the continuous casting machine is within the preset range.

[0024] When the casting speed is greater than or equal to the preset speed, it is determined that the casting speed of the continuous casting machine exceeds the preset range, and there is a high-risk working condition in the composite stirring of molten steel. Therefore, the third alternating mode is adopted, in which the second sensor performs rotational alternation and the first sensor performs traveling wave alternation.

[0025] Furthermore, the superheat of the tundish in the molten steel is obtained, and the solidification state evaluation index of the molten steel is calculated in combination with the casting speed;

[0026] Determine the stirring intensity coefficient and the base current intensity; the actual output intensity is the product of the base current intensity and the stirring intensity coefficient.

[0027] When the solidification state evaluation index of molten steel is greater than or equal to the first solidification state evaluation index, the molten steel is judged to be in the first solidification state. The stirring intensity coefficient is reduced according to the ratio of the first solidification state evaluation index to the solidification state evaluation index of molten steel, thereby reducing the actual output intensity of stirring.

[0028] When the solidification state evaluation index of molten steel is less than or equal to the second solidification state evaluation index, the molten steel is judged to be in the second solidification state. The stirring intensity coefficient is increased according to the ratio of the second solidification state evaluation index to the solidification state evaluation index of molten steel, thereby increasing the actual output intensity of stirring.

[0029] When the solidification state evaluation index of molten steel is less than the first solidification state evaluation index but greater than the second solidification state evaluation index, the molten steel is judged to be in the third solidification state. The alternation frequency is adjusted to optimize the quality of composite stirring. The stirring intensity coefficient can be finely adjusted according to the negative correlation of the solidification state evaluation index of molten steel.

[0030] Furthermore, when the installation location is in the crystallizer area or the secondary cooling zone / solidification end of continuous casting, different base current intensities are provided for the three alternating modes respectively. In the same installation location, the base current intensity of the third alternating mode is greater than that of the first alternating mode, which is greater than that of the second alternating mode.

[0031] Furthermore, when the molten steel is in the third solidification state, the alternation frequency is adjusted according to the changing trend of the molten steel solidification state evaluation index;

[0032] Calculate the characteristic value of the solidification state assessment index of molten steel. If the characteristic value of the change is greater than the standard characteristic value, it is judged that the molten steel has a trend of thinning and brittle development, the mushy zone narrows, the traveling wave alternation frequency is adjusted, and the rotational alternation frequency is adjusted according to the real-time segregation risk value.

[0033] If the change characteristic value is less than the calibration characteristic value, it is judged that the molten steel has a tendency to become viscous, the mushy region is widened, the rotation alternation frequency is adjusted, and the traveling wave alternation frequency is adjusted according to the real-time segregation risk value.

[0034] Furthermore, when the molten steel shows a trend of thinning, the alternating frequency of the traveling wave is increased according to the changing characteristic value; when the segregation risk of the molten steel exceeds the standard, the alternating frequency of the rotation is increased according to the changing characteristic value.

[0035] When the molten steel shows a tendency to become viscous, the frequency of alternating rotation is reduced based on the changing characteristic value. When the segregation risk of the molten steel exceeds the standard, the frequency of alternating traveling waves is reduced based on the changing characteristic value and the real-time segregation risk value.

[0036] Furthermore, the real-time segregation risk value is calculated based on the pulling speed and preset coefficients;

[0037] When the real-time segregation risk value exceeds the critical risk value, it is determined that the segregation risk of molten steel exceeds the standard, and dendrites are growing and bridging rapidly, so it is necessary to strengthen the breaking effect of traveling waves.

[0038] This invention provides a composite stirrer, comprising:

[0039] Magnetic shielding components are used as the housing of a stirrer to shield magnetic fields.

[0040] The iron core assembly consists of a first iron core, a second iron core, and an intermediate connecting iron core. The first iron core, the second iron core, and the intermediate connecting iron core are connected by a steel pressure ring and bolts. The iron core assembly is used to set up corresponding electromagnetic stirring zones, which include a first stirring zone, a second stirring zone, and a third stirring zone.

[0041] The sensing component includes a first sensor, a second sensor, and an intermediate connecting iron core. The sensing component is arranged around the iron core assembly and is used to control the stirring mode of the corresponding electromagnetic stirring zone.

[0042] The first sensor has induction coils arranged in a row along the throwing direction. The induction coils are located between the first iron cores and above the sensing assembly, and are used to control the stirring mode of the first stirring zone.

[0043] The second sensor has an internal annular iron core with several induction coils wound around it. It is located at the lower part of the sensing component and is used to control the stirring mode of the third stirring zone.

[0044] An intermediate connecting iron core is located between the first sensor and the second sensor to connect the first sensor and the second sensor. The bottom surface of the intermediate connecting iron core is provided with connecting teeth, which are connected to the annular iron core of the second sensor.

[0045] Compared with existing technologies, the beneficial effects of this invention are that it provides a composite electromagnetic stirrer suitable for square and round billets, which has three magnetic field forms: rotating magnetic field, spiral magnetic field, and traveling wave magnetic field. It can simultaneously output rotating magnetic field, half-traveling wave magnetic field, full-traveling wave magnetic field, spiral magnetic field, and their respective stirring modes. Different magnetic field forms and stirring modes can be selected according to different metallurgical process problems. This composite stirrer is flexibly applicable to square or round billets, generating multi-dimensional electromagnetic stirring forces in the liquid core of the billet, improving stirring efficiency, and solving quality problems in the center of the billet such as segregation, porosity, and shrinkage cavities.

[0046] Furthermore, when the sensing components are activated, in the crystallizer area, the first sensor is in front and the second sensor is behind. The third stirring zone uses an upward traveling wave motion to push the molten steel upward, replenishing the molten steel in the upper region and enhancing the temperature dissipation of the first stirring zone. The second stirring zone then uses spiral stirring to disperse the central solute elements. The first stirring zone adopts a semi-rotation mode, achieving both stirring of the molten steel and preventing surface fluctuations, thus dissipating the temperature of the molten steel.

[0047] Furthermore, in the secondary cooling and solidification end regions of continuous casting, the growth and bridging of dendrites within the billet prevent the timely replenishment of fresh induction in the continuous casting machine. Therefore, the first stirring zone uses traveling wave stirring to break up the dendrites, followed by spiral stirring to disperse the broken dendrite particles. Then, the third stirring zone employs strong large-rotation stirring, i.e., the second stirring mode of the second induction, to uniformly mix the dendrite particles and molten steel. This avoids shrinkage cavities and segregation forming in the center of the billet at high casting speeds.

[0048] Furthermore, this invention effectively solves the problems of central shrinkage, porosity, and segregation in high-speed continuous casting billets by integrating a composite stirrer that combines rotation, traveling wave, and helical magnetic fields with its intelligent control method. It can simultaneously generate multi-dimensional electromagnetic forces in the molten core of the billet, forming a three-dimensional stirring effect that penetrates the cross-section and depth, significantly improving the composition and temperature uniformity of the molten steel. Based on multiple parameters such as casting speed, superheat, and liquid surface fluctuations, the form, direction, intensity, and alternation frequency of the magnetic field are dynamically adjusted, achieving precise control from "defect prevention" to "quality optimization." Ultimately, while ensuring high-speed production efficiency, it significantly improves the equiaxed crystal ratio and internal density of the billet, making it particularly suitable for the production of high-end steel grades with stringent requirements for central quality.

[0049] Furthermore, this method performs precise risk identification and control of composite electromagnetic stirring conditions by real-time detection of continuous casting speed and crystallizer liquid level fluctuation index. First, a preliminary risk assessment is made based on whether the casting speed exceeds a preset range. Then, a secondary decision is made based on the liquid level fluctuation index. When the liquid level fluctuation index exceeds a first threshold, liquid level instability is determined, and a second alternating mode is automatically activated to fix the traveling wave magnetic field and fine-tune the rotating magnetic field to stabilize the flow field. When the liquid level fluctuation index is between the first and second thresholds and the casting speed exceeds the limit, a high-risk condition is determined, and a third alternating mode is activated, alternating between traveling wave and rotating stirring to address dendrite growth and segregation risks. When the liquid level fluctuation index is below the second threshold, the condition is determined to be stable and mild, and the first alternating mode is activated, primarily using traveling wave alternation to focus on eliminating bright white bands and breaking dendrites. This control method, through multi-parameter coupling analysis and multi-mode adaptive switching, significantly improves the stability of the stirring process and the internal quality of the cast billet under high-speed continuous casting conditions.

[0050] Furthermore, by introducing an alternating stirring mode, the inherent defects of unidirectional stirring, such as the formation of bright white bands and dead zones, are effectively overcome. The alternation of the traveling wave magnetic field up and down can break the stable solute boundary layer, significantly reducing central segregation, while simultaneously addressing dendrite breakage and temperature homogenization through directional switching. The alternation of the rotating magnetic field in the same / opposite direction can achieve a dynamic balance between strong stirring and suppression of liquid surface fluctuations. This composite alternating strategy creates high-intensity three-dimensional turbulence within the liquid core, greatly promoting the global diffusion of steel composition and heat, thereby improving the equiaxed crystal ratio, eliminating shrinkage porosity, and ensuring the stable and smooth operation of the continuous casting process.

[0051] Furthermore, by introducing a solidification state assessment index for molten steel, the electromagnetic stirring intensity is adaptively controlled based on the actual solidification state of the molten steel. Using tundish superheat and casting speed as core parameters, the solidification state of the molten steel is precisely classified into three typical types through quantitative calculation, and differentiated stirring strategies are implemented for each state. When the core of the molten steel is thin and the solidified shell is fragile, the stirring intensity is automatically reduced to effectively avoid the risk of erosion. When the molten steel is viscous and the pasty region is thick, the stirring force is increased to achieve sufficient dendrite breakage and forced homogenization of composition. In intermediate states, the stirring quality is optimized primarily by adjusting the alternating frequency. This method elevates the setting of stirring intensity from relying on experience to a dynamic scientific decision based on the solidification thermal state, ensuring that electromagnetic stirring always achieves the best metallurgical effect under safe conditions, and significantly improving the density and compositional uniformity of the cast billet under high casting speed conditions.

[0052] Furthermore, adjusting the alternating frequency can further break up dendrites and homogenize the temperature. When the liquid surface fluctuation index exceeds the standard, the alternating frequency can be reduced to decrease the fluctuations caused by alternating stirring. This invention achieves coordinated intelligent control of traveling wave and rotating alternating frequencies by tracking the dynamic change trend of the steel solidification state assessment index in real time and combining it with the real-time segregation risk value. When it is determined that the steel liquid is trending towards thinning and fragility, the traveling wave alternating frequency is automatically increased to enhance thermal diffusion and suppress the bright band. If the segregation risk exceeds the standard at the same time, the rotating alternating frequency is simultaneously increased to destroy the solute boundary layer. When it is determined that the steel liquid is trending towards viscosity, the rotating alternating frequency is reduced to maintain a strong shear flow field, and the traveling wave frequency is reduced and the directional scouring time is extended in high-risk situations to enhance dendrite breaking ability. This method actively adjusts the action mode and intensity of electromagnetic stirring by sensing the dynamic evolution of the steel liquid solidification state, so that the metallurgical effect of composite stirring is always optimally matched with the solidification process, significantly improving the equiaxed crystal ratio and compositional uniformity of the billet, while ensuring process stability. Attached Figure Description

[0053] Figure 1 This is a flowchart illustrating the control method of the composite stirrer in an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of the composite electromagnetic stirrer in an embodiment of the present invention;

[0055] Figure 3 This is a schematic diagram of the structure of the magnetic shielding assembly in an embodiment of the present invention;

[0056] Figure 4 This is a schematic diagram showing the distribution of the three stirring zones of the composite electromagnetic stirrer in an embodiment of the present invention;

[0057] Figure 5 This is a schematic diagram of the stirring function area of ​​the composite electromagnetic stirrer in an embodiment of the present invention;

[0058] Figure 6 This is a schematic diagram of the structure of the first sensor in an embodiment of the present invention;

[0059] Figure 7 This is a schematic diagram of the intermediate connecting iron core in an embodiment of the present invention;

[0060] Figure 8 This is a schematic diagram of the structure of the second sensor in an embodiment of the present invention;

[0061] Figure 9 This is a schematic diagram of the molten steel flow inside the billet of the second sensor in an embodiment of the present invention;

[0062] Figure 10 This is a metallurgical effect diagram from an embodiment of the present invention;

[0063] Figure 11 This is a schematic diagram of the stirring mode inside the crystallizer in an embodiment of the present invention;

[0064] Figure 12 This is a schematic diagram of the secondary cooling and terminal stirring modes in an embodiment of the present invention;

[0065] In the figure: 1-cast billet, 2-iron core assembly, 21-steel pressure ring, 22-first iron core, 23-second iron core, 24-intermediate connecting iron core, 3-sensing assembly, 31-first sensor, 32-second sensor, 4-magnetic shielding assembly, 41-first stirring trajectory, 5-second stirring trajectory, 6-third stirring trajectory, 7-connecting tooth. Detailed Implementation

[0066] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0067] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0068] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0069] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0070] Please see Figures 1-12 As shown, Figure 1 This is a flowchart illustrating the control method of the composite stirrer in an embodiment of the present invention; Figure 2 This is a schematic diagram of the composite electromagnetic stirrer in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the magnetic shielding assembly in an embodiment of the present invention; Figure 4 This is a schematic diagram showing the distribution of the three stirring zones of the composite electromagnetic stirrer in an embodiment of the present invention; Figure 5 This is a schematic diagram of the stirring function area of ​​the composite electromagnetic stirrer in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the first sensor in an embodiment of the present invention; Figure 7 This is a schematic diagram of the intermediate connecting iron core in an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of the second sensor in an embodiment of the present invention; Figure 9 This is a schematic diagram of the molten steel flow inside the billet of the second sensor in an embodiment of the present invention; Figure 10 This is a metallurgical effect diagram from an embodiment of the present invention; Figure 11 This is a schematic diagram of the stirring mode inside the crystallizer in an embodiment of the present invention; Figure 12 This is a schematic diagram of the second cooling and the final stirring mode in an embodiment of the present invention.

[0071] This invention provides a composite stirrer, comprising:

[0072] Magnetic shielding components are used as the housing of a stirrer to shield magnetic fields.

[0073] The iron core assembly consists of a first iron core, a second iron core, and an intermediate connecting iron core. The first iron core, the second iron core, and the intermediate connecting iron core are connected by a steel pressure ring and bolts. The iron core assembly is used to set up corresponding electromagnetic stirring zones, which include a first stirring zone, a second stirring zone, and a third stirring zone.

[0074] In practice, the core assembly surrounds the cast billet and is made of stacked silicon steel sheets. The core assembly is divided into three sections: upper, middle and lower. The silicon steel sheets between each section are assembled from A3 steel pressure rings and bolts.

[0075] The sensing component includes a first sensor, a second sensor, and an intermediate connecting iron core. The sensing component is arranged around the iron core assembly and is used to control the stirring mode of the corresponding electromagnetic stirring zone.

[0076] The first sensor has induction coils arranged in a row along the throwing direction. The induction coils are located between the first iron cores and above the sensing assembly, and are used to control the stirring mode of the first stirring zone.

[0077] In practice, the first sensor can be equipped with 1-4 columns of coils. In this embodiment, there are two columns. Each column of induction coils generates a traveling wave magnetic field along the throwing direction.

[0078] The second sensor has an internal annular iron core with several induction coils wound around it. It is located at the lower part of the sensing component and is used to control the stirring mode of the third stirring zone.

[0079] In practice, the second sensor has 12 induction coils surrounding the annular iron core, with 6 induction coils forming a group, and is divided into two groups.

[0080] An intermediate connecting iron core is located between the first sensor and the second sensor to connect the first sensor and the second sensor. The bottom surface of the intermediate connecting iron core is provided with connecting teeth, which are connected to the annular iron core of the second sensor.

[0081] In practice, the first sensor of the composite agitator can be equipped with 1-N rows of iron cores and coils, or multiple rows of coils, but only one row or a different number of rows of coils are activated. The electromagnetic force is stronger on the side of the billet closer to the coil, while there is no electromagnetic force or a weak electromagnetic force on the side without coils or with coils that are not activated. Therefore, driven by the electromagnetic force, the molten steel will flow from the side with the stronger electromagnetic force to the side with the weaker electromagnetic force, thereby activating different numbers of coils. The flow pattern of the molten steel is different, so the traveling wave agitation of the composite agitator has two different agitation modes: semi-traveling wave agitation and full-traveling wave agitation.

[0082] Specifically, the purpose of this invention is to overcome the shortcomings of existing technologies and provide a composite electromagnetic stirrer suitable for square and round billets. This electromagnetic stirrer has three magnetic field forms: rotating magnetic field, spiral magnetic field, and traveling wave magnetic field. It can simultaneously output rotating magnetic field, half-traveling wave magnetic field, full-traveling wave magnetic field, spiral magnetic field, and their respective stirring modes. Different magnetic field forms and stirring modes can be selected according to different metallurgical process problems. This composite stirrer is flexibly applicable to square or round billets, generating multi-dimensional electromagnetic stirring forces in the liquid core of the billet, improving stirring efficiency, and solving quality problems in the center of the billet such as segregation, porosity, and shrinkage cavities.

[0083] This invention provides a control method for a composite stirrer, comprising:

[0084] Step S1: Determine the stirring mode of the electromagnetic stirring zone by the sensor sequence of the composite electromagnetic stirrer and the installation position of the composite stirrer.

[0085] Step S2: Determine the surface fluctuation index of the molten steel based on the fluctuation amplitude component and frequency component of the molten steel, determine the working condition risk of the composite stirring of the molten steel in combination with the casting speed of the continuous casting machine, and determine the alternation mode of the composite electromagnetic stirring.

[0086] Step S3: Obtain the tundish superheat of the molten steel to determine the solidification state evaluation index of the molten steel, determine the solidification state of the molten steel based on the solidification state evaluation index of the molten steel, and adjust the stirring intensity in response to the solidification state in combination with the solidification state evaluation index of the molten steel and the alternating mode.

[0087] Step S4: Determine the characteristic value of the change in the solidification state evaluation index of molten steel, and determine the development trend of composite stirring of molten steel based on the characteristic value of the change;

[0088] Step S5: Obtain the real-time segregation risk value based on the casting speed of the continuous casting machine to determine the segregation risk of the molten steel;

[0089] Step S6: In response to the solidification state of the molten steel, combined with the development trend of composite stirring of molten steel and the risk of segregation of molten steel, determine the adjustment measures for the alternation parameters of the alternation mode.

[0090] The alternation parameters of the alternation mode include the traveling wave alternation frequency and the rotational alternation frequency.

[0091] It is understandable that implementers can change the form and direction of the magnetic field by adjusting the coil parameters, thereby changing the stirring mode, which will not be elaborated here.

[0092] Along the throwing direction, the composite electromagnetic stirrer is provided with three electromagnetic stirring zones, namely the first stirring zone, the second stirring zone and the third stirring zone;

[0093] The second stirring zone is a fixed spiral magnetic field stirring zone. The first and third stirring zones adopt different stirring modes according to the order of the composite electromagnetic stirring inductors and their different installation positions on the continuous casting machine.

[0094] When the composite electromagnetic stirrer is installed in the continuous casting crystallizer area, the first stirring zone is a multi-dimensional magnetic field stirring zone, and the third stirring zone is a traveling wave magnetic field stirring zone.

[0095] When the composite electromagnetic stirrer is installed in the secondary cooling zone and the solidification end of the continuous casting process, the first stirring zone is a traveling wave magnetic field stirring zone, and the third stirring zone is a rotating magnetic field stirring zone.

[0096] Specifically, since the magnetic fields generated by the first sensor and the second sensor are in different directions, for example, the first sensor generates a traveling wave magnetic field and the second sensor generates a rotating magnetic field, the magnetic fields of the iron core region in the middle between the two are superimposed to generate a spiral magnetic field. Therefore, the second stirring zone is fixed as a spiral stirring zone.

[0097] During implementation, because the magnetic fields of the first and second sensors cannot be superimposed after a certain distance, the spiral stirring effect cannot be achieved. Therefore, the height of the second stirring zone is less than 300mm.

[0098] Specifically, when the sensing components are activated, in the crystallizer area, the first sensor is in front and the second sensor is behind. The third stirring zone uses an upward traveling wave motion to push the molten steel upward, replenishing the molten steel in the upper region and enhancing the temperature dissipation of the first stirring zone. The second stirring zone further uses spiral stirring to disperse the central solute elements. The first stirring zone adopts a semi-rotation mode, achieving both stirring of the molten steel and preventing surface fluctuations, thus dissipating the temperature of the molten steel.

[0099] In the secondary cooling and solidification end regions of continuous casting, the growth and bridging of dendrites within the billet prevent the timely replenishment of fresh induction in the continuous casting machine. Therefore, the first stirring zone uses traveling wave stirring to break up the dendrites, followed by spiral stirring to disperse the broken dendrite particles. Then, the third stirring zone employs strong large-rotation stirring, i.e., the second stirring mode of the second induction, to uniformly mix the dendrite particles and molten steel. This avoids shrinkage cavities and segregation forming in the center of the billet at high casting speeds.

[0100] At high drawing speeds, molten steel exhibits quality problems such as central shrinkage cavities, porosity, and uneven composition due to central segregation.

[0101] When there are problems with central shrinkage cavities and porosity, the molten steel solidifies from the outside in. The molten steel in the center shrinks and cannot be replenished in time, forming voids.

[0102] When there is a quality problem of center segregation, alloying elements such as carbon, manganese, phosphorus and sulfur in the molten steel are pushed to the center region of the billet during the rapid solidification process, resulting in the inconsistency between the central composition and the surrounding composition.

[0103] Stirring is necessary to make the composition and temperature of the molten steel more uniform and to break up the growing dendrites, thereby improving the internal quality.

[0104] Traditional stirrers typically only have one stirring mode, such as rotating stirring only on the cross-section. Composite stirring refers to combining two or more different types of magnetic fields, such as rotating magnetic fields, traveling wave magnetic fields, and spiral magnetic fields.

[0105] The rotating magnetic field rotates within the cross-section, resolving mass issues in the surrounding and partial areas.

[0106] The traveling wave magnetic field pushes the molten steel forward or backward along the throwing direction, which can affect deeper areas and promote the exchange of matter and energy in the vertical direction.

[0107] The spiral magnetic field can be seen as a combination of rotation and traveling wave, and the stirring trajectory is three-dimensional, which can more effectively stir the center of the billet.

[0108] Specifically, this invention effectively solves the problems of central shrinkage, porosity, and segregation in high-speed continuous casting billets by integrating a composite stirrer that combines rotation, traveling wave, and helical magnetic fields with its intelligent control method. It can simultaneously generate multi-dimensional electromagnetic forces in the molten core of the billet, forming a three-dimensional stirring effect that penetrates the cross-section and depth, significantly improving the composition and temperature uniformity of the molten steel. Based on multiple parameters such as casting speed, superheat, and liquid surface fluctuations, the form, direction, intensity, and alternation frequency of the magnetic field are dynamically adjusted, achieving precise control from "defect prevention" to "quality optimization." Ultimately, while ensuring high-speed production efficiency, it significantly improves the equiaxed crystal ratio and internal density of the billet, making it particularly suitable for the production of high-end steel grades with stringent requirements for central quality.

[0109] In this embodiment, the pulling speed is controlled within the range of 1.6-2.5 m / min.

[0110] The casting speed of the continuous casting machine is detected and acquired. When the casting speed is less than the preset speed, it is determined that the casting speed of the continuous casting machine is within the preset range.

[0111] When the casting speed is greater than or equal to the preset speed, it is determined that the casting speed of the continuous casting machine exceeds the preset range, and the working condition risk of steel liquid composite stirring is identified.

[0112] The surface fluctuation index of molten steel in the continuous casting crystallizer zone is calculated by comprehensively considering the fluctuation amplitude and frequency. When the surface fluctuation index is greater than the first fluctuation index, it is determined that the surface is unstable and the longitudinal flow field needs to be fixed. Basic stirring is maintained only by finely adjusting the transverse flow field.

[0113] Specifically, when the liquid level fluctuation index is greater than the first fluctuation index, the second alternation mode is determined to be adopted, and the second sensor rotates alternately.

[0114] When the liquid level fluctuation index is less than or equal to the first fluctuation index and greater than the second fluctuation index, the casting speed of the continuous casting machine is used to determine whether there is a high-risk working condition in the composite stirring of molten steel.

[0115] Specifically, when the casting speed of the continuous casting machine exceeds the preset range, it is determined that there is a high-risk working condition in the composite stirring of molten steel, and the third alternating mode is adopted, in which the second sensor performs rotational alternation and the first sensor performs traveling wave alternation.

[0116] When the liquid surface fluctuation index is less than or equal to the second fluctuation index, the liquid surface is judged to be stable and the steel liquid composite stirring is in a stable and mild working condition. The core problem is to eliminate the white bright band and broken dendrites, and the first alternation mode is determined to be adopted.

[0117] The first volatility index has a value range of 0.5-1.0, and the second volatility index has a value range of 3.0-5.0.

[0118] In practice, continuous liquid level height data is obtained through a liquid level detector, and a time window is set. In this embodiment, the time window is 10 seconds.

[0119] Within the time window, obtain the highest and lowest liquid level values, and calculate the fluctuation amplitude component. Fluctuation amplitude component = highest liquid level - lowest liquid level.

[0120] Based on the liquid level height data, plot the liquid level height change curve. Within the same time window, obtain the number of times the liquid level height change curve crosses the target height line, and calculate the frequency component. Frequency component = number of crossings / duration of the time window.

[0121] The page fluctuation index is calculated as: scaling factor × fluctuation amplitude component × frequency component. In practice, the scaling factor is 1.

[0122] Specifically, this method uses real-time monitoring of continuous casting speed and crystallizer liquid level fluctuation index to accurately identify and control risks in composite electromagnetic stirring conditions. First, a preliminary risk assessment is made based on whether the casting speed exceeds a preset range. Then, a secondary decision is made based on the liquid level fluctuation index. When the liquid level fluctuation index exceeds a first threshold, liquid level instability is determined, and a second alternating mode is automatically activated, fixing the traveling wave magnetic field and fine-tuning the rotating magnetic field to stabilize the flow field. When the liquid level fluctuation index is between the first and second thresholds and the casting speed exceeds the limit, a high-risk condition is determined, and a third alternating mode is activated, alternating between traveling waves and rotational stirring to address dendrite growth and segregation risks. When the liquid level fluctuation index is below the second threshold, the condition is determined to be stable and mild, and the first alternating mode is activated, primarily using traveling wave alternation to focus on eliminating bright white bands and breaking dendrites. This control method, through multi-parameter coupling analysis and multi-mode adaptive switching, significantly improves the stability of the stirring process and the internal quality of the cast billet under high-speed continuous casting conditions.

[0123] The alternating modes of the composite electromagnetic stirring include a first alternating mode, a second alternating mode, and a third alternating mode;

[0124] The first alternating mode is when the composite electromagnetic stirrer is installed in the secondary cooling zone of continuous casting and at the end of solidification, the first sensor performs alternating traveling waves, but not alternating rotation.

[0125] The second alternating mode is when the composite electromagnetic stirrer is installed in the secondary cooling zone of continuous casting and at the end of solidification, the traveling waves do not alternate, and the second sensor rotates alternately.

[0126] The third alternating mode is when the composite electromagnetic stirrer is installed in the secondary cooling zone of continuous casting and at the end of solidification, the first sensor performs alternating traveling wave motion and the second sensor performs alternating rotation.

[0127] During implementation, when the composite electromagnetic stirring is in the crystallizer area, the traveling wave is fixed to be upward, which continuously promotes the floating of inclusions and stabilizes the flow field;

[0128] When the composite electromagnetic stirrer is installed in the secondary cooling zone of continuous casting and at the end of solidification, the traveling wave is fixed to downward, continuously breaking dendrites.

[0129] Specifically, by introducing an alternating stirring mode, the inherent defects of unidirectional stirring, such as the formation of bright white bands and dead zones, are effectively overcome. The alternation of the traveling wave magnetic field up and down can break the stable solute boundary layer, significantly reducing center segregation, while simultaneously addressing dendrite breakage and temperature homogenization through directional switching. The alternation of the rotating magnetic field in the same / opposite direction achieves a dynamic balance between strong stirring and suppression of liquid surface fluctuations. This composite alternating strategy creates high-intensity three-dimensional turbulence within the liquid core, greatly promoting the global diffusion of steel composition and heat, thereby improving the equiaxed crystal ratio, eliminating shrinkage porosity, and ensuring the stable and smooth operation of the continuous casting process.

[0130] The tundish superheat of molten steel is obtained by infrared temperature detection, and the molten steel solidification state evaluation index is calculated. The molten steel solidification state evaluation index = (tundish superheat / reference superheat) × (casting speed / reference casting speed).

[0131] In this embodiment, the pulling speed range is controlled between 1.6 and 2.5 m / min, the reference pulling speed range is 2.0-2.1 m / min, and the reference superheat range is 24-26℃.

[0132] When the solidification state assessment index of molten steel is greater than or equal to the first solidification state assessment index, the molten steel is judged to be in the first solidification state, with a narrow mushy zone, a thin core, and a thin solidified shell, making it fragile and easily eroded.

[0133] When the solidification state assessment index of molten steel is less than or equal to the second solidification state assessment index, the molten steel is judged to be in the second solidification state, characterized by a wide pasty zone, viscous core, and thick solidified shell. The state is stable and requires strong stirring.

[0134] When the solidification state evaluation index of molten steel is less than the first solidification state evaluation index but greater than the second solidification state evaluation index, the molten steel is judged to be in the third solidification state.

[0135] Specifically, in the secondary cooling zone or at the end of solidification, if the temperature of the molten steel is still very high and the solidified shell is very thin, excessive stirring may pose a risk such as puncturing the solidified shell.

[0136] Therefore, temperature dissipation is to bring the molten steel to a suitable, partially solidified viscous state. At this point, strengthening the stirring to break up dendrites and homogenize the composition is the most effective and safest approach.

[0137] The stirring intensity is adjusted according to the solidification state assessment index and solidification state of molten steel. A stirring intensity coefficient is set, and the benchmark value of the stirring intensity coefficient in practice is 1. The benchmark value corresponds to a safe and effective conventional current intensity verified by historical data for any installation position and stirring mode.

[0138] The actual output intensity is calculated based on the base current intensity obtained from the installation of the composite electromagnetic stirrer in the secondary cooling zone of continuous casting and the solidification end or crystallizer area, and the alternating mode adopted by the composite electromagnetic stirring. Actual output intensity = base current intensity × stirring intensity coefficient.

[0139] In practice, when the installation location is in the crystallizer area or the secondary cooling zone / solidification end of continuous casting, different base current intensities are set for the three alternating modes respectively. At the same installation location, the base current intensity of the third alternating mode is greater than that of the first alternating mode, which is greater than that of the second alternating mode.

[0140] When the molten steel is in the first solidification state, the stirring intensity coefficient is reduced according to the ratio of the first solidification state evaluation index to the molten steel solidification state evaluation index, thereby reducing the actual output intensity of stirring.

[0141] When the molten steel is in the second solidification state, the stirring intensity coefficient is increased according to the ratio of the second solidification state evaluation index to the molten steel solidification state evaluation index, thereby increasing the actual output intensity of stirring.

[0142] When the molten steel is in the third solidification state, the quality of composite stirring can be optimized by adjusting the alternating frequency. The stirring intensity coefficient can be finely adjusted based on the negative correlation of the molten steel solidification state evaluation index.

[0143] The first solidification state assessment index is 1.5, and the second solidification state assessment index is 0.6.

[0144] Specifically, by introducing a solidification state assessment index for molten steel, the electromagnetic stirring intensity is adaptively controlled based on the actual solidification state of the molten steel. Using tundish superheat and casting speed as core parameters, the solidification state of the molten steel is precisely classified into three typical types through quantitative calculations, and differentiated stirring strategies are implemented for each state. When the core of the molten steel is thin and the solidified shell is fragile, the stirring intensity is automatically reduced to effectively avoid the risk of erosion. When the molten steel is viscous and the pasty region is thick, the stirring force is increased to achieve sufficient dendrite breakage and forced homogenization of composition. In intermediate states, the stirring quality is optimized primarily by adjusting the alternating frequency. This method elevates the setting of stirring intensity from relying on experience to a dynamic scientific decision based on the solidification thermal state, ensuring that electromagnetic stirring always achieves the best metallurgical effect under safe conditions, and significantly improving the density and compositional uniformity of the cast billet under high casting speed conditions.

[0145] When the molten steel is in the third solidification state, the alternation frequency is adjusted according to the changing trend of the molten steel solidification state assessment index.

[0146] Calculate the change characteristic value of the solidification state assessment index of molten steel, wherein the change characteristic value = (current solidification state assessment index of molten steel - historical solidification state assessment index of molten steel) / initial detection cycle, where the historical solidification state assessment index of molten steel is the solidification state assessment index of molten steel obtained before the initial detection cycle.

[0147] If the change characteristic value is greater than the calibration characteristic value, it is judged that the molten steel has a trend of thinning and fragility, the mushy region narrows, the traveling wave alternation frequency is adjusted and the rotational alternation frequency is adjusted according to the real-time segregation risk value.

[0148] When the molten steel shows a trend of thinning, increasing the alternating frequency of the traveling wave according to the changing characteristic value is beneficial to the uniform dissipation of temperature and the lateral mixing of solute, and can also more effectively disperse any possible bright white bands.

[0149] Specifically, the real-time segregation risk value = preset coefficient × pulling speed / reference pulling speed. In practice, the preset coefficient is a coefficient pre-set according to the carbon equivalent and alloying elements of the steel grade. For example, it is set to 1.5 for peritectic steel and 1.0 for low carbon steel.

[0150] When the real-time segregation risk value is greater than the critical risk value, it is determined that the segregation risk of the molten steel exceeds the standard. Eliminating the bright white band is the primary task. Based on the real-time segregation risk value, the rotation alternation frequency is increased to continuously break the stable flow field and solute boundary layer at the solidification front, thereby preventing and eliminating the bright white band.

[0151] If the change characteristic value is less than the calibration characteristic value, it is judged that the molten steel has a viscous development trend, the mushy region is widened, the rotation alternation frequency is adjusted, and the traveling wave alternation frequency is adjusted according to the real-time segregation risk value.

[0152] When molten steel shows a tendency to become viscous, the frequency of rotational alternation is reduced according to the changing characteristic value to maintain a stable and powerful single large rotating flow field, thereby applying a continuous and strong shear force to the viscous molten steel.

[0153] Specifically, when the real-time segregation risk value is greater than the critical risk value, it is determined that the molten steel has become viscous and the segregation risk exceeds the standard, and the dendrites are growing and bridging rapidly, so it is necessary to strengthen the breaking effect of the traveling wave.

[0154] During implementation, the alternation frequency of traveling waves is reduced based on the changing characteristic value and the real-time segregation risk value, and the duration of the stable action of traveling waves in a specific direction in the region is extended, so that the molten steel can form a more persistent and powerful directional scouring, thereby more effectively breaking dendrites and suppressing segregation.

[0155] Specifically, in the secondary cooling zone / end, the direction is downward, while in the crystallizer zone, the direction is upward.

[0156] In practice, the calibration feature value is 0, and the critical risk value ranges from 1.3 to 1.5.

[0157] Specifically, adjusting the alternating frequency can further break up dendrites and homogenize the temperature. When the liquid surface fluctuation index exceeds the standard, the alternating frequency can be reduced to decrease the fluctuations caused by alternating stirring. This invention achieves coordinated intelligent control of traveling wave and rotating alternating frequencies by tracking the dynamic change trend of the steel solidification state assessment index in real time and combining it with the real-time segregation risk value. When it is determined that the steel is trending towards thinning and fragility, the traveling wave alternating frequency is automatically increased to enhance thermal diffusion and suppress the bright band. If the segregation risk exceeds the standard at the same time, the rotating alternating frequency is simultaneously increased to destroy the solute boundary layer. When it is determined that the steel is trending towards viscosity, the rotating alternating frequency is reduced to maintain a strong shear flow field, and the traveling wave frequency is reduced and the directional scouring time is extended in high-risk situations to enhance dendrite breaking ability. This method actively adjusts the action mode and intensity of electromagnetic stirring by sensing the dynamic evolution of the steel solidification state, so that the metallurgical effect of composite stirring is always optimally matched with the solidification process, significantly improving the equiaxed crystal ratio and compositional uniformity of the billet, while ensuring process stability.

[0158] Specifically, the second sensor can combine two stirring modes by controlling the rotation direction of the rotating magnetic field inside the coil.

[0159] In the first stirring mode of the second sensor, when the two sets of coils rotate at opposite angles, two small rotating areas are formed inside the billet.

[0160] This mode can both stir the molten steel and prevent it from churning upwards, which would cause fluctuations in the liquid surface inside the crystallizer. The two molten steel streams move in opposite directions, and after colliding, some of the flow energy is dissipated, so the molten steel is not easy to churn up and down.

[0161] The second sensor and the second stirring mode form a large rotation mode in the billet when the two sets of coils rotate at the same angle.

[0162] This stirring mode can achieve strong stirring of molten steel and achieve full mixing of molten steel. This mode is usually used in the secondary cooling and end areas of the continuous casting mold, where the molten steel has partially solidified and is relatively viscous, so strong stirring is required to mix the molten steel evenly.

[0163] This invention employs multi-phase power supply control, allowing individual control of each coil within the composite electromagnetic stirrer. During control, each coil is identified and connected to one phase of the power supply. The number of connected coils corresponds to the number of phases of the power output. By setting the phase angle φ of the power supply, the output current phase at any output port of the multi-phase power supply can be arbitrarily adjusted. Through multi-phase power supply output control, the magnetic field generated by the stirrer is adjusted.

[0164] As shown in the metallurgical effect diagram, a comparison of the two working conditions reveals that the rotary stirring method produces a center shrinkage cavity of grade 0.5, while the composite stirring method produces no center shrinkage cavity. Compared with rotary electric stirring, the composite electric stirring method demonstrates better shrinkage compensation capability and is suitable for peritectic and near-peritetic steel grades prone to shrinkage cavities.

[0165] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0166] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A compound whisk, characterized by, include: Magnetic shielding components are used as the housing of a stirrer to shield magnetic fields. The iron core assembly consists of a first iron core, a second iron core, and an intermediate connecting iron core. The first iron core, the second iron core, and the intermediate connecting iron core are connected by a steel pressure ring and bolts. The iron core assembly is used to set up corresponding electromagnetic stirring zones, which include a first stirring zone, a second stirring zone, and a third stirring zone. The sensing component includes a first sensor, a second sensor, and an intermediate connecting iron core. The sensing component is arranged around the iron core assembly and is used to control the stirring mode of the corresponding electromagnetic stirring zone. The first sensor has induction coils arranged in a row along the throwing direction. The induction coils are located between the first iron cores and above the sensing assembly, and are used to control the stirring mode of the first stirring zone. The second sensor has an internal annular iron core with several induction coils wound around it. It is located at the lower part of the sensing component and is used to control the stirring mode of the third stirring zone. An intermediate connecting iron core is located between the first sensor and the second sensor to connect the first sensor and the second sensor. The bottom surface of the intermediate connecting iron core is provided with connecting teeth, which are connected to the annular iron core of the second sensor.

2. The control method of a compound blender according to claim 1, wherein, include: The stirring mode of the electromagnetic stirring zone is determined by the sequence of the sensors in the composite electromagnetic stirrer and the installation position of the composite stirrer. The surface fluctuation index of molten steel is determined based on the amplitude and frequency components of the molten steel fluctuation. The working risk of the composite stirring of molten steel is determined in combination with the casting speed of the continuous casting machine, and the alternation mode of composite electromagnetic stirring is determined. The superheat of the tundish is obtained to determine the solidification state evaluation index of the molten steel. Based on the solidification state evaluation index, the solidification state of the molten steel is determined. The stirring intensity is adjusted in response to the solidification state, combined with the solidification state evaluation index and the alternating mode. Determine the characteristic value of the change in the solidification state assessment index of molten steel, and determine the development trend of composite stirring of molten steel based on the characteristic value of the change; Real-time segregation risk values ​​are obtained based on the casting speed of the continuous casting machine to determine the segregation risk of molten steel. In response to the solidification state of molten steel, combined with the development trend of composite stirring of molten steel and the risk of segregation of molten steel, adjustment measures for the alternation parameters of the alternation mode are determined. The alternation parameters of the alternation mode include the traveling wave alternation frequency and the rotational alternation frequency.

3. The control method of a compound blender according to claim 2, wherein, The process of determining the stirring mode of the electromagnetic stirring zone includes: The second stirring zone is a fixed spiral magnetic field stirring zone. The first and third stirring zones adopt different stirring modes according to the different installation positions of the composite electromagnetic stirring sensor on the continuous casting machine. When the composite electromagnetic stirrer is installed in the continuous casting crystallizer area, the first stirring zone is a multi-dimensional magnetic field stirring zone, and the third stirring zone is a traveling wave magnetic field stirring zone. When the composite electromagnetic stirrer is installed in the secondary cooling zone and the solidification end of the continuous casting process, the first stirring zone is a traveling wave magnetic field stirring zone, and the third stirring zone is a rotating magnetic field stirring zone.

4. The control method of a compound blender according to claim 3, wherein The surface fluctuation index of molten steel in the continuous casting crystallizer zone is calculated by comprehensively considering the fluctuation amplitude and frequency. When the liquid level fluctuation index is greater than the first fluctuation index, the second alternation mode is determined to be adopted, and the second sensor rotates alternately. When the liquid level fluctuation index is less than or equal to the second fluctuation index, the first alternation mode is determined to be adopted; When the liquid surface fluctuation index is less than or equal to the first fluctuation index and greater than the second fluctuation index, the risk condition of molten steel composite stirring is determined according to the casting speed of the continuous casting machine.

5. The control method of a compound blender according to claim 4, wherein The process of determining the risk condition of molten steel composite stirring includes: The casting speed of the continuous casting machine is obtained, and when the casting speed is less than the preset speed, it is determined that the casting speed of the continuous casting machine is in the preset range. When the casting speed is greater than or equal to the preset speed, it is determined that the casting speed of the continuous casting machine exceeds the preset range, and the molten steel composite stirring is in a high-risk condition. It is determined to use the third alternating mode, and the second inductor is rotated alternately and the first inductor is wave alternately.

6. The control method of a compound blender according to claim 5, wherein, The tundish superheat of the molten steel is obtained, and the molten steel solidification state evaluation index is calculated in combination with the casting speed. The stirring intensity coefficient and the basic current intensity are determined, and the actual output intensity is the product of the basic current intensity and the stirring intensity coefficient. When the molten steel solidification state evaluation index is greater than or equal to the first solidification state evaluation index, it is determined that the molten steel is in the first solidification state, and the stirring intensity coefficient is reduced according to the ratio of the first solidification state evaluation index to the molten steel solidification state evaluation index, and the actual output intensity of stirring is reduced. When the molten steel solidification state evaluation index is less than or equal to the second solidification state evaluation index, it is determined that the molten steel is in the second solidification state, and the stirring intensity coefficient is increased according to the ratio of the second solidification state evaluation index to the molten steel solidification state evaluation index, and the actual output intensity of stirring is increased. When the molten steel solidification state evaluation index is less than the first solidification state evaluation index and greater than the second solidification state evaluation index, it is determined that the molten steel is in the third solidification state, and the alternating frequency is adjusted, which can fine-tune the stirring intensity coefficient according to the molten steel solidification state evaluation index.

7. The control method of a compound blender according to claim 6, wherein When the installation position is the crystallizer area or the continuous casting secondary cooling zone and the solidification end, different basic current intensities are provided for the three alternating modes respectively, and the basic current intensity of the third alternating mode is greater than that of the first alternating mode and the second alternating mode at the same installation position.

8. The control method of a compound blender according to claim 7, wherein, When the molten steel is in the third solidification state, the alternating frequency is adjusted according to the change trend of the molten steel solidification state evaluation index. The change characteristic value of the molten steel solidification state evaluation index is calculated, and if the change characteristic value is greater than the calibration characteristic value, it is determined that the molten steel has a development trend of being thin and weak, the mushy zone is narrowed, the wave alternating frequency is adjusted, and the rotating alternating frequency is adjusted according to the real-time segregation risk value. If the change characteristic value is less than the calibration characteristic value, it is determined that the molten steel has a development trend of being thick and sticky, the mushy zone is widened, the rotating alternating frequency is adjusted, and the wave alternating frequency is adjusted according to the real-time segregation risk value.

9. The control method of a compound blender according to claim 8, wherein, When the molten steel has a development trend of being thin, the wave alternating frequency is increased according to the change characteristic value, and when the segregation risk of the molten steel exceeds the standard, the rotating alternating frequency is increased according to the change characteristic value. When the molten steel has a development trend of being thick, the rotating alternating frequency is reduced according to the change characteristic value, and when the segregation risk of the molten steel exceeds the standard, the wave alternating frequency is reduced according to the change characteristic value and the real-time segregation risk value.

10. The control method of a compound blender according to claim 9, wherein, The real-time segregation risk value is calculated according to the casting speed and the preset coefficient. When the real-time segregation risk value is greater than the critical risk value, it is determined that the segregation risk of the molten steel exceeds the standard, and the dendrite is growing rapidly and bridging, and the breaking action of the wave needs to be strengthened.

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