Melt stirring system with adjustable magnetic field intensity and control method

Abstract

The invention discloses a magnetic field intensity adjustable melt stirring system and a control method, and relates to the technical field of metallurgical casting, the magnetic field intensity adjustable melt stirring system comprises a crystallizer having an inner wall and an outer wall, a cooling cavity being formed between the inner wall and the outer wall; the shielding cover is fixedly arranged outside the crystallizer in a sleeving mode, and the magnetic field coil single-layer units are arranged on the inner wall of the shielding cover. The magnetic field intensity adjusting unit is electrically connected with each magnetic field coil single-layer unit and is used for dynamically adjusting the amplitude, the frequency and the waveform of the input current; the solidification interface detection module is arranged on the side wall of the crystallizer and used for detecting the melt solidification interface position in real time; the control module is in signal connection with the solidification interface detection module and the magnetic field intensity adjusting unit. The gradient magnetic field is accurately matched with the melt solidification process, dendritic crystal crushing is accurately strengthened, a traditional rotating assembly is replaced, energy loss generated by bearing friction, mechanical damping, mechanical vibration and the like is eliminated, the mechanical structure is simplified, the electromagnetic efficiency is improved, invalid power supply is avoided, and energy consumption is reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the field of nanocrystalline casting technology, and particularly relates to a molten liquid stirring system with adjustable magnetic field strength and a control method. BACKGROUND

[0002] In the field of non-ferrous metal casting, the temperature uniformity of the melt in the crystallizer directly determines the quality of crystal growth. Traditional mechanical stirring has problems such as severe disturbance and introduction of impurities, and the magnetic field stirring technology has become the mainstream solution due to its non-contact characteristics.

[0003] The magnetic field stirring technology utilizes the principle of electromagnetic induction, and by applying an alternating magnetic field outside the crystallizer, an induced current is generated inside the melt, thereby generating an electromagnetic force to drive the melt flow. The existing magnetic field stirring technology is based on non-contact, which can effectively avoid many problems of mechanical stirring, but it still has the following limitations in actual application:

[0004] (1) Static magnetic field distribution: the magnetic field distribution of the existing magnetic field stirring technology is usually static, and the magnetic field strength and distribution cannot be dynamically adjusted according to the solidification process of the melt; this leads to a mismatch between the magnetic field strength and the solidification demand at the initial and final stages of solidification, affecting the stirring effect.

[0005] (2) Limitations of rotating magnetic field: most of the existing magnetic field stirring technologies use rotating magnetic fields, which can achieve stirring of the melt, but for high-viscosity melts, the stirring efficiency is low; in addition, rotating magnetic fields require complex mechanical structures (such as rotating shields), increasing the complexity and energy consumption of the equipment.

[0006] (3) High energy efficiency: the current control method of the magnetic field coil in the existing magnetic field stirring technology is relatively simple, and usually only on-off control of the coil can be achieved, which cannot realize continuous gradient adjustment of the magnetic field strength, which not only limits the optimization of the stirring effect, but also leads to low energy utilization efficiency.

[0007] (3) Slow response speed: the existing magnetic field stirring technology generally uses a mechanical transmission chain (such as a motor-driven screw and a slider) to adjust the magnetic field range, and the response time is relatively long (such as > 2.3 seconds), which cannot match the solidification speed of the melt in real time. SUMMARY

[0008] In view of the defects of the prior art, the purpose of the present application is to provide a molten liquid stirring system with adjustable magnetic field strength and a control method. On the one hand, the control module generates a magnetic field strength control signal according to the solidification interface position, and through the magnetic field strength adjusting unit, the magnetic field strength forms a gradient distribution along the solidification direction, realizing the precise matching of the gradient magnetic field to the molten liquid solidification process. On the other hand, the solidification interface detection module detects the molten liquid solidification interface position in real time, and the control module adjusts the magnetic field strength adjusting unit based on the interface position, which can precisely strengthen the crystal fragmentation. When the solidification interface detection module captures the critical point of crystal growth, the magnetic field strength adjusting unit outputs a square wave current, generating a strong pulsating electromagnetic force, and producing an equiaxed crystal multiplication effect, i.e. the strong magnetic field breaks the crystal root and becomes an equiaxed crystal nucleus. In addition, the shielding cover of the electromagnetic stirrer is fixedly sleeved outside the crystallizer, which cancels or replaces the traditional rotating component, eliminates bearing friction loss, simplifies the mechanical structure, improves electromagnetic efficiency, avoids invalid power supply, and reduces energy consumption.

[0009] In order to achieve the above purpose, the present application provides a molten liquid stirring system with adjustable magnetic field strength, comprising:

[0010] A crystallizer, the crystallizer has an inner wall and an outer wall, and a cooling cavity is formed between the two;

[0011] An electromagnetic stirrer, the electromagnetic stirrer includes a shielding cover fixedly sleeved outside the crystallizer and a plurality of magnetic field coil single-layer units arranged on the inner wall of the shielding cover;

[0012] A magnetic field strength adjusting unit, the magnetic field strength adjusting unit is electrically connected with each of the magnetic field coil single-layer units, and is used for dynamically adjusting the amplitude, frequency and waveform of the input current;

[0013] A solidification interface detection module, the solidification interface detection module is arranged on the side wall of the crystallizer and is used for detecting the molten liquid solidification interface position in real time;

[0014] A control module, the control module is signal connected with the solidification interface detection module and the magnetic field strength adjusting unit, and is configured to generate a magnetic field strength control signal according to the solidification interface position, and make the magnetic field strength form a gradient distribution along the solidification direction through the magnetic field strength adjusting unit.

[0015] In order to solve the technical problems, the present application adopts the following technical solutions:

[0016] Further, the magnetic field strength adjusting unit includes an H-bridge inverter circuit, a pulse width modulator and a current feedback loop, wherein,

[0017] The H-bridge inverter circuit is connected to the magnetic field coil single-layer unit by a signal; the pulse width modulator is used to output PWM waves to the H-bridge inverter circuit; the current feedback loop is used to collect the coil current in real time and adjust the PWM wave duty cycle.

[0018] Further, an ultrasonic sensor array and a signal processor are included, wherein the ultrasonic sensor array is distributed along the crystallizer axis; the signal processor is used to calculate the solidification interface position based on the ultrasonic echo time difference.

[0019] Further, the control module performs:

[0020] When the solidification interface position is located at the upper part of the crystallizer, the control module controls the magnetic field strength adjustment unit to output a high-frequency low-amplitude current;

[0021] When the solidification interface position advances to the lower part of the crystallizer, the control module controls the magnetic field strength adjustment unit to output a low-frequency high-amplitude current.

[0022] Further, a cooling strength adjustment valve is also included, which is arranged at the cooling liquid inlet of the cooling cavity;

[0023] The control module synchronously regulates the cooling strength adjustment based on the solidification interface position.

[0024] In order to achieve the above purpose, the application also provides a control method for a magnetic field strength adjustable molten liquid stirring system, which is applied to the system described in any one of the above embodiments and includes the following steps:

[0025] S1: Real-time acquisition of the molten liquid solidification interface position by the solidification interface detection module;

[0026] S2: Calculation of the target magnetic field strength distribution function a according to the solidification interface position:

[0027] B(z) = B_max * exp(-k·z) a;

[0028] Wherein, B(z) is the target magnetic field strength distribution function, B_max is the maximum magnetic field strength at the interface, exp(-k·z) is the magnetic field attenuation function, k is the attenuation coefficient, and z is the distance from the solidification interface;

[0029] S3: Generation of current control parameters matched with the target magnetic field strength;

[0030] S4: Driving the magnetic field coil single-layer unit to output a gradient magnetic field by the magnetic field strength adjustment unit.

[0031] In order to solve the technical problems, the further technical solutions adopted by the application are:

[0032] Further, in step S2, the calculation target magnetic field intensity distribution function further comprises:

[0033] S21: when the solidification interface position advancing speed is greater than a threshold value, increasing the attenuation coefficient k to increase the magnetic field gradient;

[0034] S22: when the melt superheat is less than a set value, reducing B_max to reduce the dendrite fragmentation strength.

[0035] Further, it further comprises:

[0036] According to the solidification interface position, a shrinkage cavity risk area is predicted;

[0037] A pulsed strong magnetic field is generated at the axial position corresponding to the risk area.

[0038] Further, in step S3, the current control parameter comprises:

[0039] In the initial stage of solidification, a sinusoidal wave current is adopted;

[0040] In the middle-late stage of solidification, a square wave current is switched to enhance the electromagnetic force.

[0041] Further, in step S2, it further comprises:

[0042] S23: a mapping database of solidification interface position-magnetic field intensity-equiaxed crystal ratio is established;

[0043] S24: based on historical data, the attenuation coefficient k and the B_max value are dynamically optimized and updated.

[0044] Compared with the prior art, the present application has the following technical effects:

[0045] I. The composition segregation rate is significantly reduced: the control module generates a magnetic field intensity control signal according to the solidification interface position, and the magnetic field intensity adjusting unit is used to form a gradient distribution of the magnetic field intensity along the solidification direction, so as to realize the precise matching of the gradient magnetic field to the melt solidification process;

[0046] II. The equiaxed crystal ratio is greatly improved: the solidification interface detection module of the present application detects the melt solidification interface position in real time, and the control module controls the magnetic field intensity adjusting unit based on the interface position, so that the dendrite fragmentation can be precisely strengthened. When the solidification interface detection module captures the dendrite growth critical point, the magnetic field intensity adjusting unit outputs a square wave current → generates a strong pulsating electromagnetic force, and produces an equiaxed crystal proliferation effect, that is, the strong magnetic field makes the dendrite root break and become an equiaxed crystal nucleus.

[0047] III. Energy consumption is greatly optimized: the shielding cover of the electromagnetic stirrer of the present application is fixed on the outside of the crystallizer, which cancels or replaces the rotating assembly in the traditional sense, eliminates bearing friction loss, simplifies the mechanical structure, improves electromagnetic efficiency, avoids invalid power supply, and reduces energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0048] The present application will be further described below in conjunction with the drawings and specific embodiments.

[0049] Figure 1 It is a connection block diagram of the electrical system of the present application.

[0050] Figure 2 It is a flowchart of the control method of the present application.

[0051] Figure 3 It is a preferred flowchart of the control method of the present application.

[0052] Reference signs:

[0053] Crystallizer 100, inner wall 110, outer wall 120, cooling cavity 130.

[0054] Electromagnetic stirrer 200, shielding cover 210, magnetic field coil single-layer unit 220, control module 230.

[0055] Magnetic field strength adjusting unit 300, H-bridge inverter circuit 310, pulse width modulator 320, current feedback loop 330.

[0056] Solidification interface detection module 400, ultrasonic sensor array 410, signal processor 420.

[0057] Cooling intensity adjusting valve 500. DETAILED DESCRIPTION

[0058] In order to make the technical means, creative features, purposes and effects realized by the present application easy to understand, the present application will be further described below in conjunction with specific drawings.

[0059] Example 1

[0060] Referring to Figure 1 which shows one example of the magnetic field strength adjustable molten liquid stirring system provided by the present application.

[0061] As can be seen from the figure, the present example includes a crystallizer 100, which has an inner wall 110 and an outer wall 120, forming a cooling cavity 130 therebetween;

[0062] An electromagnetic stirrer 200, which includes a shielding cover 210 fixed on the outside of the crystallizer 100 and a plurality of magnetic field coil single-layer units 220 arranged on the inner wall of the shielding cover 210.

[0063] a magnetic field strength adjusting unit 300, which is electrically connected with each of the magnetic field coil single-layer units 220, and is configured to dynamically adjust the amplitude, frequency and waveform of the input current;

[0064] a solidification interface detection module 400, which is arranged on the sidewall of the crystallizer 100, and is configured to detect the position of the solidification interface of the molten metal in real time;

[0065] a control module 230, which is signal-connected with the solidification interface detection module 400 and the magnetic field strength adjusting unit 300, and is configured to generate a magnetic field strength control signal according to the position of the solidification interface, and to make the magnetic field strength form a gradient distribution along the solidification direction through the magnetic field strength adjusting unit 300;

[0066] In the embodiment, the control module generates a magnetic field strength control signal according to the position of the solidification interface, and makes the magnetic field strength form a gradient distribution along the solidification direction through the magnetic field strength adjusting unit, so as to realize the precise matching of the gradient magnetic field to the solidification process of the molten metal;

[0067] In addition, the solidification interface detection module detects the position of the solidification interface of the molten metal in real time, and the control module adjusts the magnetic field strength adjusting unit based on the position of the interface, so as to precisely strengthen the breaking of the dendrites. When the solidification interface detection module captures the critical point of the dendrite growth, the magnetic field strength adjusting unit outputs a square wave current, so as to generate a strong pulsating electromagnetic force and produce an equiaxed crystal multiplication effect, i.e., the strong magnetic field makes the root of the dendrites break and become equiaxed crystal nuclei.

[0068] In addition, the shielding cover of the electromagnetic stirrer in the embodiment is fixedly arranged outside the crystallizer, which cancels or replaces the rotating assembly in the traditional sense, eliminates the friction loss of the bearing, simplifies the mechanical structure, and improves the electromagnetic efficiency.

[0069] Preferably, in the above-mentioned magnetic field strength adjustable molten metal stirring system, the magnetic field strength adjusting unit 300 comprises an H-bridge inverter circuit 310, a pulse width modulator 320 and a current feedback loop 330, wherein the H-bridge inverter circuit 310 is signal-connected with the magnetic field coil single-layer units 220; the pulse width modulator 320 is configured to output a PWM wave to the H-bridge inverter circuit 310; and the current feedback loop 330 is configured to collect the coil current in real time and adjust the duty cycle of the PWM wave.

[0070] In the embodiment, the circuit mechanism of the H-bridge inverter circuit + PWM modulator + current feedback loop is built, which solves the technical problem that the traditional linear power supply cannot realize the fast switching of square wave / pulse due to slow response. The current feedback loop makes the electromagnetic force accuracy achieve ±1% accuracy, the square wave reduces the invalid harmonic loss compared with the sine wave, and the square wave driving saves energy.

[0071] Further preferably, in the above-mentioned molten metal stirring system with adjustable magnetic field strength, the solidification interface detection module 400 comprises an ultrasonic sensor array 410 and a signal processor 420, wherein the ultrasonic sensor array 410 is distributed along the axis of the crystallizer 100; the signal processor 420 is used to calculate the solidification interface position based on the time difference of ultrasonic echoes;

[0072] In the present embodiment, by means of axial distribution of ultrasonic array + echo time delay calculation of interface position, the technical problem of failure to capture the instantaneous movement of the solidification interface caused by temperature detection lag is solved, the interface positioning accuracy is controlled within 0.5 mm, the response time is within 0.1 s, so as to ensure that the magnetic field gradient matches the molten metal solidification process in real time.

[0073] Preferably, in the above-mentioned molten metal stirring system with adjustable magnetic field strength, the control module 230 performs: when the solidification interface position is located at the upper part of the crystallizer 100, the control module 230 controls the magnetic field strength adjusting unit 300 to output high-frequency low-amplitude current;

[0074] When the solidification interface position advances to the lower part of the crystallizer 100, the control module 230 controls the magnetic field strength adjusting unit 300 to output low-frequency high-amplitude current;

[0075] In the present embodiment, by means of switching control and adjustment of high-frequency low-amplitude current (50 Hz / 0.5 T) and low-frequency high-amplitude current (20 Hz / 1.2 T), the technical problems of high-frequency weak field inhibiting turbulence caused by strong magnetic field slag entrapment at the initial stage of solidification, and low-frequency strong field enhancing dendrite breakage caused by insufficient stirring at the end of solidification are avoided, the slag entrapment rate is reduced, and the proportion of equiaxed crystals is improved.

[0076] Preferably, in the above-mentioned molten metal stirring system with adjustable magnetic field strength, it further comprises a cooling intensity adjusting valve 500, which is arranged at the cooling liquid inlet of the cooling cavity 130;

[0077] The control module 230 synchronously controls the cooling intensity adjusting valve 500 based on the solidification interface position;

[0078] In the present embodiment, by means of the linkage control mode of cooling intensity adjusting valve and solidification interface, the problem of out-of-control solidification speed caused by disconnection between cooling and magnetic field is avoided, the stability of solidification speed is improved, the shrinkage cavity rate is reduced, and local overheating is avoided.

[0079] Embodiment 2

[0080] Reference is made to Figure 2 and Figure 3As shown in the control method for the molten liquid stirring system with adjustable magnetic field strength provided by the application, the embodiment 2 can be used for the system described in any of the embodiment 1.

[0081] As shown in the figure, the present example includes:

[0082] S1: Real-time acquisition of the molten liquid solidification interface position by the solidification interface detection module 400;

[0083] S2: Calculation of the target magnetic field strength distribution function a according to the solidification interface position;

[0084] B(z) = B_max * exp(-k·z)a;

[0085] Wherein, B(z) is the target magnetic field strength distribution function, B_max is the maximum magnetic field strength at the interface, exp(-k·z) is the magnetic field decay function, k is the decay coefficient, and z is the distance from the solidification interface;

[0086] S3: Generation of the current control parameter matching the target magnetic field strength;

[0087] S4: Driving of the magnetic field coil single-layer unit 220 to output the gradient magnetic field by the magnetic field strength adjustment unit 300;

[0088] In the present embodiment, the magnetic field strength adjustment unit makes the magnetic field strength form a gradient distribution along the solidification direction: B(z) = B_max·exp(-k·z), so as to realize the precise matching of the gradient magnetic field to the molten liquid solidification process;

[0089] In addition, the solidification interface detection module detects the molten liquid solidification interface position in real time, so that the control module regulates the magnetic field strength adjustment unit based on the interface position, which can precisely strengthen the dendrite breaking, when the solidification interface detection module captures the dendrite growth critical point, the control module increases B_max, the magnetic field strength adjustment unit outputs the square wave current to generate the strong pulse electromagnetic force, and the equiaxed crystal proliferation effect is generated, that is, the strong magnetic field makes the dendrite root break and become an equiaxed crystal nucleus.

[0090] In addition, the magnetic field strength adjustment unit realizes the on-demand adjustment of the current amplitude / frequency and the square wave current driving, avoids the invalid power supply, and reduces the energy consumption.

[0091] Preferably, in the control method for the molten liquid stirring system with adjustable magnetic field strength, in step S2, the calculation of the target magnetic field strength distribution function further includes:

[0092] S21: When the solidification interface position advancing speed is greater than a threshold value, the decay coefficient k is increased to increase the magnetic field gradient;

[0093] S22: when the superheat of the molten metal is less than a set value, reducing B_max to reduce the dendrite fragmentation strength;

[0094] In the embodiment, when the solidification speed is greater than the threshold value, the attenuation coefficient k value is increased, and when the superheat is less than the set value, the B_max value is reduced, thereby avoiding the technical problems of dendrite coarsening caused by sudden change of the solidification speed and cracks caused by strong magnetic field at low superheat, and greatly reducing the dendrite size and the crack occurrence rate through design of the target magnetic field strength distribution function.

[0095] Preferably, in the control method of the magnetic field strength adjustable molten metal stirring system, a shrinkage cavity risk area is predicted according to the solidification interface position; and a pulsed strong magnetic field is generated at an axial position corresponding to the risk area.

[0096] In the embodiment, the pulsed strong magnetic field is generated at the axial position by predicting the shrinkage cavity risk area, thereby overcoming the technical problem that the traditional homogeneous magnetic field cannot be used for shrinkage repair, and ensuring that the pulsed magnetic field promotes the backfilling of the melt, so that the shrinkage cavity volume is greatly reduced and the ingot density is improved.

[0097] Preferably, in the control method of the magnetic field strength adjustable molten metal stirring system, in step S3, the current control parameter includes: using a sine wave current in the initial stage of solidification; and switching to a square wave current in the middle and later stages of solidification to enhance the electromagnetic force.

[0098] In the embodiment, the technical scheme of using a sine wave current in the initial stage of solidification and switching to a square wave current in the middle and later stages of solidification solves the problem of insufficient sine wave electromagnetic force in the later stage of solidification, and ensures that the electromagnetic force multiple is improved in the later stage, thereby improving the equiaxed crystal ratio.

[0099] Preferably, in the control method of the magnetic field strength adjustable molten metal stirring system, in step S2, it further includes: S23: establishing a mapping database of solidification interface position-magnetic field strength-equiaxed crystal ratio; and S24: dynamically optimizing and updating the attenuation coefficient k and the B_max value based on historical data.

[0100] In the embodiment, the attenuation coefficient k and the B_max value are dynamically optimized by establishing the interface position-magnetic field-equiaxed crystal mapping database, thereby solving the problem of poor universality of a single alloy parameter, improving the adaptability of multiple alloys, and greatly reducing the process development cycle.

[0101] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A molten metal stirring system with adjustable magnetic field strength, characterized in that, include: A crystallizer (100) having an inner wall (110) and an outer wall (120) forming a cooling chamber (130) between them; An electromagnetic stirrer (200) includes a shield (210) fixedly sleeved on the outside of the crystallizer (100) and a plurality of single-layer magnetic field coil units (220) disposed on the inner wall of the shield (210). A magnetic field strength adjustment unit (300) is electrically connected to each of the magnetic field coil single-layer units (220) and is used to dynamically adjust the amplitude, frequency and waveform of the input current. Solidification interface detection module (400), the solidification interface detection module (400) is disposed on the side wall of the crystallizer (100) and is used to detect the position of the solidification interface of the melt in real time; The control module (230), which is signal-connected to the solidification interface detection module (400) and the magnetic field strength adjustment unit (300), is configured to: generate a magnetic field strength control signal according to the position of the solidification interface; and make the magnetic field strength form a gradient distribution along the solidification direction through the magnetic field strength adjustment unit (300).

2. The system according to claim 1, characterized in that, The magnetic field strength adjustment unit (300) includes an H-bridge inverter circuit (310), a pulse width modulator (320), and a current feedback loop (330). The H-bridge inverter circuit (310) is used to signal-connect the single-layer unit (220) of the magnetic field coil; the pulse width modulator (320) is used to output a PWM wave to the H-bridge inverter circuit (310); and the current feedback loop (330) is used to collect the coil current in real time and adjust the duty cycle of the PWM wave.

3. The system according to claim 2, characterized in that, The solidification interface detection module (400) includes an ultrasonic sensor array (410) and a signal processor (420), wherein the ultrasonic sensor array (410) is distributed along the axial direction of the crystallizer (100); and the signal processor (420) is used to calculate the position of the solidification interface based on the ultrasonic echo time difference.

4. The system according to claim 1, characterized in that, The control module (230) executes: When the solidification interface is located at the top of the crystallizer (100), the control module (230) controls the magnetic field strength adjustment unit (300) to output a high-frequency low-amplitude current; When the solidification interface position advances to the lower part of the crystallizer (100), the control module (230) controls the magnetic field strength adjustment unit (300) to output a low-frequency high-amplitude current.

5. The system according to claim 1, characterized in that, It also includes a cooling intensity regulating valve (500), which is located at the coolant inlet of the cooling chamber (130); The control module (230) synchronously adjusts the cooling intensity adjustment (500) based on the position of the solidification interface.

6. A control method for a molten metal stirring system with adjustable magnetic field strength, characterized in that, Applied to the system according to any one of claims 1-5, comprising: S1: The position of the solidification interface of the melt is obtained in real time through the solidification interface detection module (400); S2: Calculate the target magnetic field intensity distribution function a based on the location of the solidification interface. B(z) = B_max * exp(-k·z)a; Where B(z) is the target magnetic field intensity distribution function, B_max is the maximum magnetic field intensity at the interface, exp(-k·z) is the magnetic field attenuation function, k is the attenuation coefficient, and z is the distance from the solidification interface. S3: Generate current control parameters that match the target magnetic field strength; S4: The magnetic field strength adjustment unit (300) drives the single-layer unit (220) of the magnetic field coil to output a gradient magnetic field.

7. The control method according to claim 6, characterized in that, In step S2, the calculation of the target magnetic field intensity distribution function further includes: S21: When the propulsion speed of the solidification interface is greater than the threshold, increase the attenuation coefficient k to improve the magnetic field gradient; S22: When the superheat of the melt is less than the set value, reduce B_max to reduce the dendrite fracture strength.

8. The control method according to claim 6, characterized in that, Also includes: Predict the shrinkage cavity risk area based on the location of the solidification interface; A pulsed strong magnetic field is generated at the axial position corresponding to the risk area.

9. The control method according to claim 6, characterized in that, In step S3, the current control parameters include: A sinusoidal current was used in the initial stage of solidification. In the later stages of solidification, the current is switched to a square wave to enhance the electromagnetic force.

10. The control method according to claim 6, characterized in that, Step S2 also includes: S23: Establish a mapping database of solidification interface location, magnetic field strength, and equiaxed crystal ratio; S24: Dynamically optimize and update the attenuation coefficient k and B_max values ​​based on historical data.

Images