A solenoid type electromagnetic stirrer

Abstract

The present invention discloses a solenoid electromagnetic stirrer, comprising: a shell, a solenoid coil, a crucible, a resistance wire heating unit and a heat insulation layer; a coil support wall is arranged in the shell, the solenoid coil is wound on the coil support wall, and the solenoid coil can provide radial and axial electromagnetic forces for the metal melt after being energized; the resistance wire heating unit is used to heat the crucible and keep the metal in a molten state; the heat insulation layer is used to isolate high temperature and protect the solenoid coil. In the present invention, solenoid coils of different numbers and positions can generate different radial and axial electromagnetic force distributions, wherein the typical force field distribution is that the radial electromagnetic force is unevenly distributed along the axial direction, so that the metal melt generates turbulent motion with a "double loop" trajectory, and the turbulence is greatly improved compared with the traditional electromagnetic stirring, and the disorder of the melt motion is increased, so the stirring efficiency of the solenoid electromagnetic stirrer is greatly improved compared with the traditional electromagnetic stirrer.

Description

Technical Field

[0001] The invention belongs to the field of electromagnetic casting, and more specifically, relates to a solenoid type electromagnetic stirrer. Background Art

[0002] With the rapid development of science and technology and manufacturing industry, a single metal material is difficult to meet the design requirements of industry. Therefore, the development of composite materials with excellent properties of multiple materials has become one of the current research hotspots. Among them, particle-reinforced metal matrix composite materials have been widely used in various fields such as aviation, aerospace, and automobiles due to their simple preparation, superior performance, and low cost. The mechanical stirring method uses a rotating paddle to stir the metal melt with reinforced particles to fully mix the reinforced particles with the metal melt. It is currently the most mature method for preparing particle-reinforced metal matrix composite materials. However, mechanical stirring also has defects such as easy introduction of impurities, uneven stirring force, and strict high temperature resistance requirements for the stirring paddle material. The electromagnetic stirring technology has the advantages of non-contact, no stirring blind spot, not easy to introduce impurities, and improved metal microstructure. It has great application prospects in the field of particle-reinforced metal matrix composite casting. At present, there are three main stirring forms of conventional electromagnetic stirring technology: (1) rotating magnetic field type, in which the molten metal rotates under the action of the rotating magnetic field due to the circumferential electromagnetic force; (2) traveling wave magnetic field type, in which the molten metal moves linearly under the action of the traveling wave magnetic field due to the electromagnetic force with a constant direction; (3) spiral magnetic field type, that is, the rotating magnetic field and the traveling wave magnetic field are superimposed, and the molten metal is simultaneously subjected to the circumferential force and the axial force under the action of the spiral magnetic field, and moves up or down in a spiral. The invention patents with publication numbers CN107116191A and CN103182495A respectively point out that the composite spiral electromagnetic stirrer can produce the above three different stirring modes under different working modes. However, conventional electromagnetic stirring still has the following defects: (1) The mixing efficiency is low. The stirring electromagnetic force has no radial component, which makes the molten metal flow less turbulent, which is not conducive to heat transfer inside the molten metal and mixing of the molten metal with reinforced particles. (2) The stirring speed is constrained by the skin effect of the electromagnetic force. To speed up the flow rate of the molten metal, it is necessary to increase the working current frequency. However, the increase in frequency causes the electromagnetic force on the melt to be mainly distributed in the area close to the winding, and the central area is almost not affected by the electromagnetic force. (3) The circumferential rotation of the molten metal forms a large central vortex on the liquid surface, which can easily cause the particles to agglomerate in the casting of particle-reinforced metal matrix composites, thereby reducing the performance of the composite material. (4) The electromagnetic stirrer has many windings, a complex structure, and is not easy to maintain. Summary of the invention

[0003] In view of the defects of the prior art, the purpose of the present invention is to provide a solenoid type electromagnetic stirrer, aiming to solve the technical problems of the prior art in the casting of particle-reinforced metal matrix composite materials, such as poor mixing effect and low efficiency of the metal melt and the reinforced particles due to the single stirring form and low turbulence of the metal melt flow.

[0004] The present invention provides a solenoid electromagnetic stirrer, comprising: a shell, a solenoid coil, a crucible, a resistance wire heating unit and an insulation layer; a coil support wall is arranged in the shell, the solenoid coil is wound on the coil support wall, and the solenoid coil can provide radial and axial electromagnetic forces after being energized; the resistance wire heating unit is used for heating the crucible and maintaining the molten state of the metal; the insulation layer is used for isolating high temperature and protecting the solenoid coil.

[0005] When working, the magnetic field generated by the solenoid coil at its height center is greater than the magnetic field at both ends, the electromagnetic force exerted on the middle of the molten metal is greater than the electromagnetic force exerted on the two ends, the molten metal will have an inward flow trend, and the entire melt forms a "double-circuit" flow trajectory with radial inward flow in the middle and outward flow at both ends. This "double-circuit" turbulent motion similar to mechanical stirring can efficiently stir the entire melt.

[0006] As an embodiment of the present invention, when the solenoid coil is a single coil, it is wound on the coil support wall; the magnetic field generated by the solenoid coil is largest in the middle of the coil and slightly smaller at both ends, and the electromagnetic force exerted on the molten metal in the crucible at the same time also presents a distribution characteristic of being larger in the middle and smaller at both ends.

[0007] As an embodiment of the present invention, when the solenoid coil is a single coil, it is arranged at the lower end of the outer side of the molten metal. During operation, the electromagnetic force applied to the lower end of the molten metal is larger, while the electromagnetic force applied to the upper end is smaller. The molten metal at the lower end flows radially inward while the molten metal at the upper end flows outward. The molten metal forms an overall circulation loop, and the flow form is turbulent.

[0008] As an embodiment of the present invention, when the solenoid coil is a single coil, it is arranged at the upper end of the outer side of the molten metal. When working, the electromagnetic force applied to the upper end of the molten metal is larger, and the electromagnetic force applied to the lower end is smaller. The molten metal at the upper end flows inward and the molten metal at the lower end flows outward. The molten metal forms an overall circulation loop, and the flow form is turbulent.

[0009] As another embodiment of the present invention, when the solenoid coil is two coils, the two coils are respectively arranged at the upper end and the lower end of the outer side of the metal melt, and are symmetrically distributed about the height center of the crucible.

[0010] As another embodiment of the present invention, when the solenoid coil is two coils, the two coils are respectively arranged at the upper end and the lower end of the outer side of the metal melt, and are asymmetrically distributed about the height center of the crucible.

[0011] Wherein, the solenoid coil is a solid copper wire or a hollow copper tube. When a hollow copper tube is used, water can be passed through the tube to further improve the heat dissipation performance of the coil.

[0012] In an embodiment of the present invention, the solenoid electromagnetic stirrer also includes: a frequency converter and a power supply, one end of the frequency converter is connected to the solenoid coil, and the other end of the frequency converter is connected to the power supply, the frequency converter can arbitrarily change the frequency of the current passing through the solenoid coil between 0 and 100 Hz, and the power supply can arbitrarily change the effective value of the current passing through the solenoid coil between 0 and 400A.

[0013] In an embodiment of the present invention, the resistance wire heating unit includes: a resistance wire, a thermocouple and a temperature regulation circuit; the resistance wire is used to heat the crucible, the thermocouple is used to detect the crucible temperature and feed the temperature back to the temperature regulation circuit, and the temperature regulation circuit keeps the crucible temperature at the user-set temperature based on the thermocouple feedback.

[0014] The present invention has the following technical effects:

[0015] (1) High stirring efficiency. Since the solenoid coil generates radial and axial electromagnetic forces, and the radial electromagnetic force is unevenly distributed along the axial direction, the metal melt forms a flow loop similar to mechanical stirring. The movement form is turbulent, and the turbulence is greatly improved compared with traditional electromagnetic stirring, which increases the disorder of the metal melt movement. Therefore, the stirring efficiency of the solenoid electromagnetic stirrer is greatly improved compared with the traditional electromagnetic stirrer. At the same time, it also has the advantages of traditional electromagnetic stirring such as non-contact, no stirring blind spot, not easy to bring in impurities, and improved metal microstructure.

[0016] (2) Simple control and diversified stirring forms. Electromagnetic forces with different distribution characteristics can be generated by simply changing the position and combination of the solenoids. Therefore, different stirring forms can be customized according to the different physical properties of the molten metal to be stirred or the molten metal containing reinforced particles. It is suitable for a variety of scenarios such as metal continuous casting, particle-reinforced metal matrix composite casting, and semi-solid casting.

[0017] (3) Reduce the limitation of stirring effect caused by increasing the current frequency. When the current frequency increases, the electromagnetic force increases, but due to the skin effect, the electromagnetic force is mainly distributed on the outside of the metal melt, and the electromagnetic stirring force inside is relatively small. The electromagnetic force applied to the metal melt by the solenoid electromagnetic stirrer is mainly radial force, and the metal melt will generate radial velocity and circulate between the outside and the inside, reducing the influence of the small stirring force inside the metal melt.

[0018] (4) During the stirring process, no central vortex is formed on the surface of the molten metal. Therefore, in the casting of particle-reinforced metal matrix composites, the reinforced particles will not agglomerate in the area near the liquid surface.

[0019] (5) The main structure of the magnetic field generating device is a solenoid coil, which has a simple structure, small size, stable performance and long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of a solenoid electromagnetic stirrer provided in an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the magnetic flux lines of the magnetic field generated by the solenoid coil;

[0022] FIG3( a ) is a schematic diagram showing the phase relationship among the magnetic field, induced electric field, induced current and electromagnetic force in a metal melt;

[0023] Figure 3(b) is a schematic diagram of a typical force field and flow field of a solenoid electromagnetic stirrer;

[0024] FIG4( a ) is a cross-sectional view of the flow field under stirring in the single coil mode of a solenoid electromagnetic stirrer;

[0025] FIG4( b ) is a cross-sectional view of the flow field under stirring by a conventional mechanical stirrer;

[0026] Figure 5 It is a structural diagram and a flow field cross-sectional diagram of the first embodiment of the present invention;

[0027] Figure 6 It is a structural diagram and a flow field cross-sectional diagram of a second embodiment of the present invention;

[0028] Figure 7 It is a structural diagram and a flow field cross-sectional diagram of a third embodiment of the present invention;

[0029] Figure 8 is a structural diagram and a flow field cross-sectional diagram of a fourth embodiment of the present invention;

[0030] Fig. 9 It is a structural diagram and a flow field cross-sectional diagram of the fifth embodiment of the present invention.

[0031] In the figure, 1 is a shell, 2 is a shell cover, 3 is a solenoid coil, 4 is a crucible, 5 is a heating resistance wire, 6 is an insulating layer, and 7 is a metal melt (liquid metal). DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] The present invention is applied to the fields of electromagnetic casting and electromagnetic material processing, and is particularly directed to electromagnetic stirrers used in metal continuous casting, semi-solid casting, and particle-reinforced metal matrix composite material casting. The present invention provides a solenoid stirrer with a simple structure, a long service life, various stirring forms, and high stirring efficiency, which can drive the metal melt to perform turbulent motion, thereby achieving stirring of the metal melt or rapid and uniform mixing of the metal melt with solid particles.

[0034] The solenoid stirrer provided by the present invention comprises: a shell, a shell cover, a solenoid coil, a crucible, a resistance wire heating unit and an insulating layer; the shell plays a supporting, isolating and protecting role; the shell cover plays an insulating and protective role; the solenoid coil is wound on the coil supporting wall inside the shell; the crucible is surrounded by the resistance wire and used as a container; the resistance wire heating unit heats the crucible and keeps the metal in a molten state; the insulating layer is located on the outside of the resistance wire, and its role is to protect the solenoid coil and isolate the resistance wire from high temperature.

[0035] In the embodiment of the present invention, the solenoid coil has two forms: a single coil and a combination of multiple coils. A single solenoid coil can generate an electromagnetic force that is stronger in the middle of the coil and weaker at both ends, which is suitable for metal continuous casting; multiple solenoid coils can be combined in different numbers and positions to generate electromagnetic stirring forces with different distributions, and the combination form can be changed according to different usage scenarios, metal matrices with different physical properties, and reinforcing particles.

[0036] In an embodiment of the present invention, the solenoid coil is connected to a frequency converter and a power supply, which provides electrical energy to the frequency converter and the coil, and can arbitrarily change the effective value of the current passing through the solenoid coil between 0 and 400A. The frequency converter can arbitrarily change the frequency of the current passing through the coil between 0 and 100Hz. According to the principle of electromagnetic induction, the current amplitude is kept unchanged. The higher the frequency, the greater the electromagnetic stirring force generated. However, due to the skin effect, the area of ​​action of the electromagnetic force is also smaller. Although the solenoid electromagnetic stirrer provided by the present invention can provide radial electromagnetic force to reduce the current frequency and increase the restriction on the stirring effect, it is not enough to completely offset it. Metal melts and reinforced particles with different physical properties correspond to different optimal current frequencies and sizes when stirring. The frequency converter and power supply enable the present invention to achieve the optimal current frequency and size in different usage scenarios.

[0037] The shape of the solenoid coil is not limited to solid copper wire, and a hollow copper tube with water can be used to further improve its heat dissipation capacity.

[0038] In the embodiment of the present invention, the resistance wire heating unit is composed of a resistance wire, a thermocouple and a temperature regulating circuit. The resistance wire is used to heat the crucible, and the thermocouple is used to detect the crucible temperature and feed the temperature back to the temperature regulating circuit. The temperature regulating circuit can keep the crucible temperature at the user-set temperature according to the thermocouple feedback.

[0039] In the present invention, the energized solenoid coil generates an alternating magnetic field B, such as Figure 2 As shown, the magnetic field consists of radial and axial components. The magnetic field excites an induced electric field E in the metal melt. According to the law of electromagnetic induction, the phase of the induced electric field E lags behind the alternating magnetic field. Since the metal melt is an inductive load, the phase of the induced current density J in the melt will lag behind the induced electric field According to the Ampere force formula, the electromagnetic force per unit volume of molten metal is Since the magnetic field has radial and axial components, the metal melt is subject to axial and radial electromagnetic forces. The axial electromagnetic force can accelerate the axial movement of the metal melt and increase the speed and turbulence of the melt movement. As for the radial electromagnetic force, due to the influence of the lag phase α of the current density, the time and value of the electromagnetic force inward in the radial direction on the metal melt during one power-on cycle are greater than the electromagnetic force in the radial direction outward (i.e., the radial electromagnetic force in Figure 3(a)). ), so the metal melt has a tendency to flow inward. With the increase of working time, the flow rate of the metal melt continues to increase until the movement resistance and the electromagnetic force reach a dynamic balance.

[0040] Because the magnetic field generated by the solenoid coil at its height center is greater than the magnetic field at both ends, the electromagnetic force on the middle of the molten metal is greater than the electromagnetic force on both ends. According to the above analysis, the molten metal will have a tendency to flow inwards. Due to the conservation of mass of the molten metal, the molten metal will eventually form a "double-circuit" flow trajectory with the middle flowing inwards and the two ends flowing outwards. This "double-circuit" turbulent motion similar to mechanical stirring can efficiently stir the entire melt. Therefore, the solenoid electromagnetic stirrer provided by the present invention has the advantages of both mechanical stirrers and traditional electromagnetic stirrers.

[0041] In order to further illustrate the solenoid electromagnetic stirrer provided by the embodiment of the present invention, it is now described in detail as follows with reference to the accompanying drawings and in combination with specific examples:

[0042] First embodiment:

[0043] like Figure 1As shown, the solenoid stirrer provided by the present invention comprises: a shell 1, a shell cover 2, a solenoid coil 3, a crucible 4, a resistance wire heating unit 5 and an insulation layer 6; the shell 1 plays a supporting, isolating and protective role; the shell cover 2 plays an insulating and protective role; the solenoid coil 3 is wound on the coil support wall inside the shell 1, and its height is slightly smaller than that of the crucible 4; the crucible 4 is surrounded by a resistance wire and serves as a stirring container; the resistance wire heating unit 5 is composed of a resistance wire, a thermocouple and a temperature regulating circuit (the thermocouple and the temperature regulating circuit are not shown in the figure), the resistance wire is used to heat the crucible and keep the metal in a molten state, the thermocouple is used to detect the crucible temperature and feed the temperature back to the temperature regulating circuit, and the temperature regulating circuit can keep the crucible temperature at the user-set temperature according to the thermocouple feedback; the insulation layer 6 is located outside the resistance wire, and its function is to protect the solenoid coil and isolate the resistance wire from high temperature. When the metal melting temperature is low, silica aerogel can be used as the insulation layer material, and when the metal melting temperature is high, a hollow copper layer can be used for insulation by water cooling.

[0044] like Figure 5 As shown, the stirrer coil is composed of a single solenoid coil 3. Since the magnetic field generated by the solenoid coil 3 is the largest in the middle of the coil and slightly smaller at the two ends, the electromagnetic force exerted on the molten metal 7 in the crucible at the same time is also distributed in a larger middle and smaller two ends. Figure 2 As shown, in one power-on cycle of the solenoid coil 3, the coil 3 generates an alternating magnetic field B, which consists of a radial component and an axial component. The magnetic field excites an induced electric field E in the metal melt 7. According to the law of electromagnetic induction, the phase of the induced electric field E lags behind the alternating magnetic field. Since the metal melt 7 is an inductive load, the phase of the induced current density J in the melt will lag behind the induced electric field According to the Ampere force formula, the electromagnetic force per unit volume of molten metal is Since the magnetic field has radial and axial components, the metal melt is subjected to axial and radial electromagnetic forces. The axial electromagnetic force can accelerate the axial movement of the metal melt, increasing the speed and turbulence of the melt movement. For the radial electromagnetic force, the lag phase α of the current density will cause the metal melt 7 to be subjected to the electromagnetic force inward in the radial direction for a longer time and a greater value than the electromagnetic force in the radial direction outward in one power-on cycle, as shown in Figure 3(a). (with radial outward as the positive direction), and because of the magnetic field distribution characteristics of the solenoid coil 3, which is larger in the middle and smaller at both ends and the conservation of metal melt mass, the metal melt in the middle will flow inwards and the metal melt at both ends will flow outwards, forming a complete circulation trajectory. As the working time increases, the flow rate of the metal melt continues to increase until the motion resistance and the electromagnetic force reach a dynamic balance.

[0045] As shown in Figure 4, the middle metal melt moves inwards to the vicinity of the axis under the electromagnetic force and then flows upward and downward. This "double-circuit" turbulent motion similar to mechanical stirring can efficiently stir the entire melt. Therefore, the solenoid electromagnetic stirrer provided by the present invention has the advantages of both mechanical stirrers and traditional electromagnetic stirrers.

[0046] This embodiment is suitable for metal continuous casting, semi-solid casting, etc., and is particularly suitable for particle-reinforced metal-based composite casting. The core step of the particle-reinforced metal-based composite casting is the mixing of the metal melt and the reinforced solid particles. The reinforced particles are sinking solid particles with a density slightly greater than that of the metal matrix. When static, the particles will sink at a slower speed. In this embodiment, the particles located in the upper half of the metal melt 7 are subject to the force of the upward circulation of the fluid, which hinders their sinking; the particles located in the lower half of the metal melt 7 are subject to the force of the downward circulation of the fluid, first accelerating their sinking, and then circulating to the middle of the metal melt 7. The circulation of the entire fluid makes the reinforced particles with a density slightly greater than that of the metal matrix evenly distributed in the metal melt 7.

[0047] Second embodiment:

[0048] The difference between this embodiment and the first embodiment is that this embodiment uses two solenoid coils 3-1 and 3-2, the two solenoid coils 3-1 and 3-2 have fewer turns than the first embodiment, so the height is reduced, and are respectively connected to a set of power supply and inverter.

[0049] like Figure 6 As shown, the two solenoid coils 3-1 and 3-2 are respectively located at the upper and lower ends of the outer side of the metal melt 7, and are symmetrically distributed about the height center of the crucible 4. Since the magnetic field is mainly concentrated near the solenoid coils 3-1 and 3-2, the electromagnetic force on the two ends of the metal melt 7 is larger, and the electromagnetic force on the middle part is smaller. The metal melt at the two ends flows inward, while the metal melt in the middle flows outward. The metal melt forms an overall circulation loop, the flow form is turbulent, and the circulation direction is opposite to that of the first embodiment.

[0050] This embodiment is suitable for metal continuous casting, semi-solid casting, etc., and is particularly suitable for particle-reinforced metal-based composite casting. The core step of the particle-reinforced metal-based composite casting is the mixing of the metal melt and the reinforced solid particles. The reinforced particles are floating solid particles with a density slightly smaller than that of the metal matrix. When static, the particles will float up at a slower speed. In this embodiment, the particles located in the upper half of the metal melt 7 are subject to the force of the downward circulation of the fluid, which hinders their floating; the particles located in the lower half of the metal melt 7 are subject to the force of the upward circulation of the fluid, first accelerating to float to the middle of the metal melt 7, and then circulating to the bottom of the metal melt 7. The circulation of the entire fluid makes the reinforced particles with a density slightly smaller than that of the metal matrix evenly distributed in the metal melt 7.

[0051] Third embodiment:

[0052] The difference between this embodiment and the first embodiment is that the solenoid coil 3 is located at the lower end of the outer side of the metal melt 7, and the number of turns of the solenoid coil 3 is reduced compared with the first embodiment, so the height is reduced. The solenoid coil 3 is connected to a power supply and a frequency converter.

[0053] like Figure 7 As shown, the solenoid coil 3 is located at the lower end of the outer side of the molten metal 7. Since the magnetic field is mainly concentrated near the solenoid coil 3, the electromagnetic force on the lower end of the molten metal is larger, and the electromagnetic force on the upper end is smaller. The molten metal at the lower end flows inwards while the molten metal at the upper end flows outwards. The molten metal forms an overall circulation loop, the flow form is turbulent, and the circulation direction is opposite to that of the fourth embodiment.

[0054] This embodiment is suitable for metal continuous casting, semi-solid casting, etc., and is particularly suitable for particle-reinforced metal matrix composite casting. The core step of the particle-reinforced metal matrix composite casting is the mixing of metal melt and reinforced solid particles. The reinforced particles are sinking solid particles with a density greater than that of the metal matrix and the particles can sink at a faster speed when static. In this embodiment, the upward flow of the metal melt 7 drives the particles to move toward the melt surface, and the sinking reinforced particles are evenly distributed in the metal melt 7 through the circulating flow.

[0055] Fourth embodiment:

[0056] The difference between this embodiment and the third embodiment is that this embodiment uses a solenoid coil 3 located at the upper end of the outer side of the metal melt 7. The solenoid coil 3 is connected to a set of power supply and frequency converter.

[0057] like Figure 8 As shown, the solenoid coil 3 is located at the upper end of the outer side of the molten metal 7. Since the magnetic field is mainly concentrated near the solenoid coil 3, the electromagnetic force on the upper end of the molten metal is larger, and the electromagnetic force on the lower end is smaller. The molten metal at the upper end flows inwards while the molten metal at the lower end flows outwards. The molten metal forms an overall circulation loop, and the flow form is turbulent.

[0058] This embodiment is suitable for metal continuous casting, semi-solid casting, etc., and is particularly suitable for particle-reinforced metal matrix composite casting. The core step of the particle-reinforced metal matrix composite casting is the mixing of metal melt and reinforced solid particles. The reinforced particles are floating solid particles with a density less than that of the metal matrix and the particles can float up at a relatively fast speed when static. In this embodiment, the downward flow of the metal melt 7 drives the particles to move to the bottom of the crucible, and the floating reinforced particles are evenly distributed in the metal melt 7 through the circulating flow.

[0059] Fifth embodiment:

[0060] The difference between this embodiment and the second embodiment is that the two solenoid coils 3-1 and 3-2 used in this embodiment are asymmetrically distributed in the height direction about the height center of the crucible 4, and the two solenoid coils 3-1 and 3-2 are respectively connected to a set of power supply and inverter.

[0061] like Fig. 9 As shown, the two solenoid coils 3-1 and 3-2 are respectively located at the upper and lower ends of the outer side of the metal melt 7, and are asymmetrically distributed about the height center of the crucible 4, and the lower end coil 3-2 is closer to the height center of the crucible 4. Since the magnetic field is mainly concentrated near the solenoid coils 3-1 and 3-2, the electromagnetic force on both ends of the metal melt 7 is relatively large, and the electromagnetic force on the area between the coils 3-1 and 3-2 is relatively small. The metal melts at both ends flow inward, converge at the height center of the coils 3-1 and 3-2, and flow outward. The metal melt forms an integral circulation loop, and the flow form is turbulent. The circulation direction is similar to that of the first embodiment.

[0062] This embodiment is applicable to metal continuous casting, semi-solid casting, etc., and is particularly applicable to particle-reinforced metal matrix composite casting. The core step of the particle-reinforced metal matrix composite casting is the mixing of metal melt and reinforced solid particles. The density of the sinking reinforced particles applicable to this embodiment is between the first embodiment and the third embodiment.

[0063] In addition to the above embodiments, the solenoid coil 3 may have different numbers and positions to meet the requirements of various flow forms, and may be specifically matched according to different usage scenarios, metal matrices and reinforcing particles with different physical properties.

[0064] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A solenoid electromagnetic stirrer, characterized in that: include: housing, solenoid coil, crucible, resistance wire heating unit and thermal insulation; A coil support wall is provided in the housing, the solenoid coil is wound on the coil support wall, and the solenoid coil provides radial and axial electromagnetic forces when energized; The resistance wire heating unit is used to heat the crucible and keep the metal in a molten state; the insulation layer is used to isolate high temperature and protect the solenoid coil; When working, the magnetic field generated by the solenoid coil at its height center is greater than the magnetic field at both ends, and the electromagnetic force on the middle of the molten metal is greater than the electromagnetic force on both ends. The molten metal will have a radial inward flow trend, and the molten metal will form a "double-circuit" flow trajectory with the middle part flowing inward and the two ends flowing outward, thereby efficiently stirring the entire melt; When the solenoid coil is a single coil, it is wound on the coil support wall, and the magnetic field generated by the solenoid coil is the largest in the middle of the coil and slightly smaller at both ends. At the same time, the electromagnetic force exerted on the molten metal in the crucible is also distributed in a larger middle and smaller end distribution; When the solenoid coil is a single coil, it is arranged at the upper end of the outer side of the molten metal. During operation, the upper end of the molten metal is subjected to a larger electromagnetic force, while the lower end is subjected to a smaller electromagnetic force. The molten metal at the upper end flows radially inward while the molten metal at the lower end flows outward. The molten metal forms an overall circulation loop, and the flow form is turbulent.

2. The solenoid electromagnetic stirrer according to claim 1, characterized in that: The solenoid coil is a solid copper wire or a hollow copper tube.

3. The solenoid electromagnetic stirrer according to claim 1, characterized in that: The solenoid electromagnetic stirrer also includes: a frequency converter and a power supply, one end of the frequency converter is connected to the solenoid coil, and the other end of the frequency converter is connected to the power supply, the frequency converter can arbitrarily change the frequency of the current passing through the solenoid coil between 0 and 100 Hz, and the power supply can arbitrarily change the effective value of the current passing through the solenoid coil between 0 and 400A.

4. The solenoid electromagnetic stirrer according to claim 1, characterized in that: The resistance wire heating unit comprises: a resistance wire, a thermocouple and a temperature regulating circuit; The resistance wire is used to heat the crucible, and the thermocouple is used to detect the temperature of the crucible and feed the temperature back to the temperature regulating circuit. The temperature regulating circuit keeps the temperature of the crucible at the user-set temperature according to the thermocouple feedback.

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