CN111225465B - Superconducting induction heating device with mixed magnetic circuit - Google Patents
Superconducting induction heating device with mixed magnetic circuit Download PDFInfo
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- CN111225465B CN111225465B CN202010096905.9A CN202010096905A CN111225465B CN 111225465 B CN111225465 B CN 111225465B CN 202010096905 A CN202010096905 A CN 202010096905A CN 111225465 B CN111225465 B CN 111225465B
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Abstract
The application discloses mixed magnetic circuit superconductive induction heating device includes: the superconducting coil comprises a magnetic conductive iron core, a superconducting coil arranged around the magnetic conductive iron core and a plurality of parallel iron yokes distributed around the circumference of the magnetic conductive iron core, wherein an upper magnetic conductive plate is arranged at the upper end of the magnetic conductive iron core, and a lower magnetic conductive plate is arranged at the lower end of the magnetic conductive iron core; the superconducting coil is connected with an external power supply through a current lead so that the superconducting coil bears current and further generates a magnetic field; a first air gap for placing a workpiece to be heated is formed between the upper end surface/lower end surface of each iron yoke and the side wall of the upper magnetic conductive plate/lower magnetic conductive plate; after the workpiece to be heated is placed in the first air gap, the magnetic conduction iron core conducts the magnetic field generated by the superconducting coil to the iron yokes connected in parallel so as to form a plurality of series-parallel mixed magnetic circuits. The device that this application provided can heat a plurality of workpieces of treating to heat simultaneously to and increase the heating efficiency of the workpiece of treating to heat, mixed magnetic circuit makes the device have and is corresponding to the better regulatory function of heating technology and power.
Description
Technical Field
The application relates to the technical field of superconducting power electrician equipment, in particular to a superconducting induction heating device with a mixed magnetic circuit.
Background
The induction heating technology is widely applied to the industrial production of forge piece penetrating heating, surface quenching heating, medium-high frequency welding, induction melting and the like. The application in the diathermy treatment aspect comprises the expanding of a steel pipe, the hot forging of a steel billet, the hot rolling and the extension processing of nonferrous metals such as copper, aluminum and the like; applications in industrial heat treatment include case hardening, diathermy hardening, tempering and stress relief, annealing and normalizing, weld annealing, powder metal sintering, and the like; applications in welding include metal tube welding, metal plate welding, and the like; applications of induction heating in metal smelting include ferrous metal, non-ferrous metal smelting, casting, and the like.
The induction heating technology is applied to ferrous metal smelting and calendering processing industries in related fields, and the non-ferrous metal smelting and calendering processing industries are listed in six high-energy-consumption industries. According to statistics, the total amount of electric energy consumed by the induction heating equipment accounts for 1-5% of the total consumption of national electric energy, the total consumption of the electric energy in 2015 China is 59202.87 hundred million kilowatt hours, and the consumption of the induction heating equipment is 563.03-2960.14 million kilowatt hours. In the application of the current large and medium-sized induction heating equipment, the effective electric-heat conversion efficiency for heating steel is 50-60%; the effective electrothermal conversion efficiency of non-ferromagnetic workpieces such as copper, aluminum and the like is between 35 and 45 percent.
The principle of the traditional induction heating technology is Faraday's law of electromagnetic induction and Joule-Lenz's law of current heat effect, alternating current generates an alternating magnetic field, the alternating magnetic field induces eddy currents in conductors, and the conductors are heated by the Joule heat of the eddy currents. A conventional induction heating system mainly includes an alternating power supply, an induction coil, a cooling system, and the like. Factors that affect the effective electrothermal conversion efficiency of the induction heating apparatus are joule heat loss in the coil and material characteristics of the heating workpiece and the coil. In the joule heat loss aspect of the coil, the induction coil is generally wound by conventional metal conductors such as copper wires or copper pipes, and the joule heat of the conductor itself is very large due to high frequency and large current, for example, the joule heat of the induction coil of the induction melting furnace accounts for more than 20% of the rated power of the induction furnace, and the proportion of the joule heat of the conductor itself is larger for induction heating equipment with few turns of the induction coil such as a welded pipe. For example, in the case of induction heating equipment in hot forging, metal working and deep processing lines, joule heat of the coil is removed by forced cooling water in the copper pipe or the coil cooling tank.
The principle of the novel superconducting induction heating technology is as follows: the superconductive main magnet of the direct current excitation produces the strong direct current magnetic field, and the work piece of aluminium matter or copper rotates in the direct current background magnetic field and cuts the magnetic line of force, and then forms the vortex in the work piece and produces joule heat and heat the work piece to technology temperature. The novel superconducting induction heating equipment mainly comprises a direct-current excitation power supply, a superconducting main magnetic system, a mechanical rotating system and the like. In the operation process of the novel superconducting induction heating equipment, induced current in a workpiece generates braking reverse torque which hinders rotation, mechanical energy is converted into heat energy through the action of electromagnetic induction, a direct-current-carrying superconducting coil in a superconducting main magnet system almost has no loss, the main loss of the superconducting coil is the loss of a low-temperature cooling system and the loss of a rotating motor, and the loss of the rotating motor is dominant in the high-power superconducting induction heating equipment, so that the efficiency of the novel superconducting induction heating equipment is expected to reach 80% -85%. In addition, the novel superconducting induction heating technology also has the advantages of uniform heating, good heating repeatability and no need of high-power reactive compensation.
By utilizing the characteristic that the superconducting material can carry current without resistance under the direct current condition, a novel direct current superconducting induction heating mode is provided in European patent 1582091B 1: the method is characterized in that direct current is introduced into a superconducting coil, a static magnetic field is generated in space, a workpiece to be processed is placed on the plane where the coil is located, the direction of main flux generated by the superconducting coil is perpendicular to the axis of the workpiece, the workpiece rotates around the axis in the static magnetic field, and induced current is excited to generate heat. US7339145B2 proposes an electromagnetic heating device for heating high conductivity, non-ferromagnetic materials by rotating the workpiece in a static magnetic field, the workpiece lying in the plane of the coils.
The defects of the prior art mainly comprise: 1. the main magnet structure in the existing superconducting direct current induction heating technology can only heat one or two limited workpieces at the same time; 2. the superconducting magnet has low utilization rate, and the advantages of the high magnetic field are not fully reflected in the superconducting induction heating technology.
The present invention has been made in view of the above circumstances.
Disclosure of Invention
In view of this, the embodiments of the present application provide a method for solving the problem that the superconducting induction heating technology can only heat limited one or two workpieces at the same time, and the utilization rate of the superconducting magnet is low.
The embodiment of the application adopts the following technical scheme:
the embodiment of the present application provides a superconducting induction heating apparatus with a hybrid magnetic circuit, the superconducting induction heating apparatus includes:
the magnetic conduction iron core is a columnar iron core, an upper magnetic conduction plate is arranged at the upper end of the magnetic conduction iron core, and a lower magnetic conduction plate is arranged at the lower end of the magnetic conduction iron core;
the superconducting coil surrounds the magnetic core and is connected with an external power supply through a current lead so as to enable the superconducting coil to bear current and further generate a magnetic field;
the superconducting induction heating device further comprises a plurality of parallel iron yokes distributed circumferentially around the magnetic conductive iron core, a first air gap is formed between the upper end face of each iron yoke and the side wall of the upper magnetic conductive plate, and/or a first air gap is also formed between the lower end face of each iron yoke and the side wall of the lower magnetic conductive plate, and the first air gap is used for placing a workpiece to be heated;
after the workpiece to be heated is placed in the first air gap, an external power supply inputs current to the superconducting coil, the magnetic conduction iron core conducts the magnetic field generated by the superconducting coil to a plurality of iron yokes connected in parallel to form a plurality of magnetic circuits connected in parallel, and the workpiece to be heated can rotate under the action of external force to generate induction current to heat the workpiece to be heated.
In a preferred embodiment of the above superconducting induction heating apparatus, each yoke is further provided with at least one second air gap, and the second air gap is also used for placing a workpiece to be heated; after the magnetic field generated by the superconducting coil is conducted to the iron yokes connected in parallel by the magnetic conductive iron core to form a plurality of magnetic circuits connected in parallel, the workpiece to be heated placed in the second air gap can rotate under the action of external force to generate induction current to heat the workpiece to be heated.
In a preferred embodiment of the superconducting induction heating apparatus, the second air gaps of the adjacent two yokes are offset from each other.
In a preferred embodiment of the above superconducting induction heating device, the plurality of parallel iron yokes are evenly distributed around the magnetically permeable iron core; and/or the number of the parallel iron yokes is even.
In a preferred embodiment of the above superconducting induction heating apparatus, the superconducting coil is formed by winding a superconducting wire in a solenoid configuration or a pancake configuration; and/or the superconducting coil is a superconducting coil impregnated with epoxy resin or paraffin.
In a preferred embodiment of the superconducting induction heating apparatus described above, the current lead is a superconducting current lead or a variable-section copper lead; and/or the columnar iron core is cylindrical.
In a preferred embodiment of the above superconducting induction heating apparatus, an upper end surface of each yoke and a side wall of the upper magnetic conductive plate opposite to the upper end surface of the yoke are both concave structures; and/or the lower end surface of each iron yoke and the side wall of the lower magnetic conduction plate opposite to the lower end surface of the iron yoke are both in a concave structure.
In a preferred embodiment of the above superconducting induction heating apparatus, the rotation speed of the workpiece to be heated is set to 120rpm to 3000 rpm.
In a preferred embodiment of the above superconducting induction heating apparatus, the superconducting induction heating apparatus further comprises a dewar vessel having a housing cavity housing the superconducting coil; the accommodating cavity can provide a vacuum environment for the superconducting coil.
In a preferred embodiment of the above superconducting induction heating apparatus, the superconducting induction heating apparatus further includes a refrigeration system, a refrigerator cold head is disposed on the dewar container, and the refrigeration system is connected to the refrigerant head and configured to provide low-temperature cold energy for making the superconducting coil in a superconducting state.
In the superconducting induction heating device of this application, superconducting core is located superconducting coil's center, plays the magnetic conduction effect, through a plurality of parallelly connected iron yokes around magnetic core circumference distribution, make after letting in current in superconducting coil, magnetic core constitutes a closed magnetic circuit passageway with every parallelly connected iron yoke respectively, every closed magnetic circuit passageway is equivalent to a series magnetic circuit, the superconducting induction heating device that this application provided forms a series-parallel hybrid magnetic circuit on the whole. Furthermore, a first air gap and a second air gap are arranged on each closed magnetic path to place a workpiece to be heated, the workpiece to be heated rotates in a background magnetic field generated by the superconducting coil, the magnetic flux in the workpiece to be heated changes due to the non-uniform magnetic field and the rotation of the workpiece to be heated, induced voltage can be generated on the workpiece to be heated according to the Lenz law, induced eddy current is generated, heat is generated in the workpiece to be heated by the eddy current, and the workpiece to be heated is heated to the temperature of diathermanous treatment. Thereby realizing the purpose of heating a plurality of workpieces to be heated simultaneously. In addition, a heating cycle is from the placement of the workpiece to be heated until the workpiece to be heated is heated to the process temperature, and a rapid heating cycle can increase the heating efficiency of the workpiece to be heated. And the superconducting magnet with high magnetic field intensity is beneficial to improving the heating power, so that the heating time is shortened, and the heat loss is reduced. The hybrid magnetic circuit allows the device to have a better regulation function corresponding to the heating process and power.
The superconducting induction heating device forms a plurality of series-parallel mixed magnetic circuits, magnetic flux generated by the superconducting coil is equally divided, the advantage of a superconducting strong magnetic field is fully utilized, and the magnetic utilization rate of the superconducting coil is increased. Further through increasing the superconductive high-intensity magnetic field utilization ratio, combined with the background magnetic field that has increased the work piece that waits to heat in first air gap, the second air gap, shorten the period of leaking heat that the work piece radiation after the heating and convection produced through adjusting the heating beat, and then the heating beat of positive promotion work piece that waits to heat.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a schematic view of the overall structure of a superconducting induction heating apparatus according to an embodiment of the present application, in which a superconducting coil is omitted for clarity);
fig. 2 is a schematic magnetic circuit diagram of a superconducting induction heating apparatus according to an embodiment of the present application;
fig. 3 is a schematic view showing a specific structure of a superconducting induction heating apparatus according to an embodiment of the present application;
FIG. 4 is a schematic structural diagram of a Dewar vessel according to an embodiment of the present application;
FIG. 5 is a schematic structural view of a superconducting coil according to an embodiment of the present application;
FIG. 6a is a graph of heating power of a workpiece to be heated versus magnetic flux density on each parallel magnetic circuit;
FIG. 6b is a graph of the heating power of the workpiece to be heated versus the rotational speed of the workpiece to be heated.
Description of the figure numbering: 1-a magnetically permeable iron core; 11-upper magnetic conductive plate; 12-lower magnetic conductive plate; 2-iron yoke; 31-a first air gap; 32-a second air gap; 4-a dewar vessel; 41-inner cylinder; 42-an outer cylinder; 43-upper cover plate; 44-refrigerator cold head; 5-a superconducting coil; 51-current leads; h-the workpiece to be heated.
Detailed Description
As described in the background, the deficiencies of the prior art are mainly reflected in: the main magnet structure in the existing superconducting direct current induction heating technology can only heat one or two limited workpieces at the same time; the utilization rate of the superconducting magnet is low, and the advantages of the high magnetic field are not fully reflected in the superconducting induction heating technology; when the superconducting induction heating main magnet heats a workpiece, excessive radiation and heat leakage generated by convection occupy the time in the heating rhythm.
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The technical solutions provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.
Fig. 1 is a schematic view of the entire structure of a superconducting induction heating apparatus according to an embodiment of the present application. As shown in fig. 1, the superconducting induction heating apparatus of the present application includes a magnetically permeable core 1, a superconducting coil (the superconducting coil is not shown in fig. 1), and a plurality of parallel-connected iron yokes 2. Wherein, the magnetic conductive iron core 1 is a columnar iron core, and the upper end of the magnetic conductive iron core 1 is provided with an upper magnetic conductive plate 11, and the lower end of the magnetic conductive iron core 1 is provided with a lower magnetic conductive plate 12; the superconducting coil surrounds the magnetic core 1 and is connected with an external power supply through a current lead so that the superconducting coil generates current and further generates a magnetic field; the yokes 2 are circumferentially distributed around the magnetically permeable iron core 1, a first air gap 31 is arranged between the upper end face of each yoke 2 and the side wall of the upper magnetically permeable plate 11, a first air gap 31 is also arranged between the lower end face of each yoke 2 and the side wall of the lower magnetically permeable plate 12, and the first air gap 31 is used for placing a workpiece H to be heated.
An external power supply can input current to the superconducting coil through the current lead, and the superconducting coil can generate a strong magnetic field by applying large current based on the non-resistance characteristic of the superconducting material. The magnetic conductive iron core 1 is positioned in the center of the superconducting coil and can play a magnetic conductive role, namely, the magnetic conductive iron core 1 guides the high-intensity magnetic field generated by the superconducting coil to carry out parallel connection of magnetic circuits, namely, the magnetic conductive iron core 1 conducts the high-intensity magnetic field generated by the superconducting coil to a plurality of iron yokes 2 which are connected in parallel to form a plurality of magnetic circuits which are connected in parallel. As shown in fig. 2, fig. 2 shows a schematic view of a magnetic circuit of the superconducting induction heating apparatus of the present application. After current is introduced into the superconducting coil, the magnetic conductive iron core 1 and each parallel iron yoke 2 form a closed magnetic path channel. As will be appreciated by those skilled in the art, each closed magnetic circuit channel corresponds to a series magnetic circuit, and the superconducting induction heating device provided by the present application integrally forms a series-parallel hybrid magnetic circuit superconducting induction heating device.
Specifically, in this embodiment, the superconducting coil functions as a magnetic source, which may be a superconducting magnet formed by winding a YBCO superconducting wire cooled by a liquid nitrogen temperature zone in a solenoid configuration or a pancake configuration, and the configuration of the superconducting coil may also be a series-parallel structure of multiple solenoids or multiple pancake coils. Those skilled in the art can select a suitable configuration of the superconducting coil according to actual needs, for example, the superconducting coil of the embodiment of the present application can be wound by using existing superconducting materials, including but not limited to NbTi, Nb3 Sn; MgB2, a Bi-based superconducting material, a Y-based superconducting material, an iron-based superconducting material, and the like, which are not limited in the present application. It is to be noted here that the design criteria regarding the magnetomotive force of the superconducting coil are as follows: the magnetomotive force of the superconducting coil should meet the magnetic induction requirements of the background magnetic field of the first air gap 31. For example, the magnetomotive force of the superconducting coil can be obtained by multiplying the available space structural size of the superconducting induction heating apparatus of the present application and the number of turns constrained by the size of the superconducting wire and the critical current constrained by the operating temperature region of the superconducting coil and the magnetic field of the superconducting coil.
The magnetic conductive iron core 1 is positioned in the center of the superconducting coil and is used for gathering a central magnetic field generated by the superconducting coil. As shown in fig. 1, in the present embodiment, the magnetically permeable core 1 is cylindrical, that is, the cross section of the magnetically permeable core 1 is circular. Those skilled in the art can also set the magnetic conductive iron core 1 into other column shapes according to actual needs, for example, the cross section of the magnetic conductive iron core is rectangular, triangular, regular polygonal, etc., which is not limited in this application. As an example, the magnetically permeable core 1 is a ferromagnetic material, and may be specifically an electrical pure iron, a magnetically permeable silicon steel sheet, an amorphous alloy material, or the like. The magnetic conductive iron core 1 of the embodiment of the application is a single integral cylinder, and the single integral cylinder is characterized by having a large integral magnetic field density, wherein the concept of the magnetic field density refers to the ratio of a magnetic field to a sectional area in an iron core column.
With continued reference to fig. 1, in the present embodiment, the upper magnetic conducting plate 11 at the upper end of the magnetic conducting core 1 and the lower magnetic conducting plate 12 at the lower end of the magnetic conducting core 1 are both plate-shaped bodies with regular polygonal cross sections, and the upper magnetic conducting plate 11 and the lower magnetic conducting plate 12 are symmetrically disposed at two ends of the magnetic conducting core 1. As an example, the number of the iron yokes 2 connected in parallel is six. Accordingly, the cross sections of the upper magnetic conductive plate 11 and the lower magnetic conductive plate 12 may be regular dodecagon (i.e. the upper magnetic conductive plate 11 and the lower magnetic conductive plate 12 have twelve sides), six yokes 2 are uniformly distributed around the magnetic conductive iron core 1, and each yoke 2 is shaped like a "]". For example, if the edges of the upper magnetic conductive plate 11 and the lower magnetic conductive plate 12 are numbered 1, 2, and 3 … 12 in the clockwise/counterclockwise direction, the edges 1, 3, 5, 7, 9, and 11 may be respectively and correspondingly connected in parallel with one iron yoke 2. Thus, the six yokes 2 form a symmetrical structure with the magnetically permeable core 1 as the center. Because the six iron yokes 2 of the embodiment are symmetrically arranged by taking the magnetic conductive iron core 1 as the center, the formed parallel magnetic circuits have a symmetrical structure and good magnetic conductivity consistency, and the magnetic symmetry between the parallel magnetic circuits is ensured.
Those skilled in the art can also set other numbers of iron yokes 2 according to actual needs, and accordingly, the shapes of the upper magnetic conductive plate 11 and the lower magnetic conductive plate 12 can also be set according to actual needs. For example, the number of the iron yokes 2 may also be set to be an even number of 2, 4, 8, etc., and the cross sections of the upper magnetic conductive plate 11 and the lower magnetic conductive plate 12 may also be set to be other suitable regular polygons, which is not limited in the present application.
Further, the upper end face/lower end face of each yoke 2, and the side walls of the upper magnetic conductive plate 11/lower magnetic conductive plate 12 opposite to the upper end face/lower end face of the yoke 2 are designed as uniform magnetic field panels. As a feasible scheme, the workpiece H to be heated may be a cylinder, and the upper end surface of each yoke 2 and the side wall of the upper magnetic conductive plate 11 opposite to the upper end surface of the yoke 2 are both concave structures; and the lower end surface of each iron yoke 2 and the side wall of the lower magnetic conduction plate 12 opposite to the lower end surface of the iron yoke 2 are both in a concave structure. In this way, a circular space with an upper opening and a lower opening is formed between the upper end face/the lower end face of each yoke 2 and the side wall of the upper magnetic conductive plate 11/the lower magnetic conductive plate 12, and preferably, the center of the circle of the "circular space" is concentric with the center of the workpiece H to be heated, so that the consistency of the magnetic field can be ensured after the workpiece H to be heated is placed.
After the workpiece H to be heated is placed in the first air gap 31, the workpiece H can rotate under the action of external force, and in the process that the workpiece to be heated rotates under the background magnetic field, the magnetic lines of force are cut to generate eddy currents so as to heat the workpiece to be heated to the process temperature. The rotation of the workpiece H to be heated can be driven by corresponding driving devices, and the application does not limit specific driving devices, and a person skilled in the art can select a suitable driving device as required.
The operating principle of the superconducting induction heating device of the application is as follows: after current is introduced into the superconducting coil, a strong magnetic field is generated, the magnetic conduction iron core 1 conducts the strong magnetic field generated by the superconducting coil to the plurality of parallel iron yokes 2, and the workpiece H to be heated rotates in the background magnetic field generated by the superconducting coil (the workpiece H to be heated can be driven to rotate by corresponding driving equipment). At this time, due to the non-uniform magnetic field and the rotation motion of the workpiece to be heated, the magnetic flux in the workpiece to be heated H changes, induced voltage can be generated on the workpiece to be heated H according to lenz's law, and then induced eddy current is generated, and the eddy current generates heat in the workpiece to be heated H, so that the workpiece to be heated H is heated to the temperature of diathermy treatment. The heating efficiency of the workpiece H to be heated can be increased by a rapid heating cycle from the time when the workpiece H to be heated is placed until the workpiece H to be heated is heated to the process temperature.
In the present embodiment, as shown in fig. 1, six parallel iron yokes 2 form 12 first air gaps 31, so that 12 workpieces to be heated can be placed at the same time, that is, 12 workpieces H to be heated can be heated at the same time, and the purpose of heating a plurality of workpieces H to be heated at the same time is achieved. In addition, the superconducting magnet with high magnetic field intensity is beneficial to improving the heating power, so that the heating time is shortened, and the heat loss is reduced.
In a specific embodiment, with continued reference to fig. 1, each parallel yoke 2 is further provided with a second air gap 32, and the second air gap 32 is also used for placing a workpiece H to be machined; after the magnetic core 1 transmits the magnetic field generated by the superconducting coil to the parallel iron yokes 2 to form a plurality of series-parallel mixed magnetic circuits, the workpiece H to be heated placed in the second air gap 32 can rotate under the action of external force to generate induction current to heat the workpiece to be processed. Specifically, the second air gap 32 is designed with reference to the first air gap 31, and a uniform magnetic field panel is designed on two opposite surfaces of the second air gap 32. For example, two opposite surfaces of the second air gap 32 are both concave structures, so that a circular space with an upper opening and a lower opening is also formed between the two opposite surfaces of the second air gap 32, and preferably, the center of the circle of the "circular space" is concentric with the center of the workpiece H to be heated, so that the consistency of the magnetic field can be ensured after the workpiece H to be heated is placed in the circular space. The heating principle of the workpiece H to be heated placed in the second air gap 32 is the same as that of the workpiece H to be heated placed in the first air gap 31, and specific reference is made to the above description, and details are not repeated here. As an example, the second air gaps 32 on two adjacent iron yokes 2 are arranged in a staggered manner, so that the second air gaps 32 are not all arranged on the same horizontal plane, and thus a larger space for placing and taking out the workpiece H to be heated can be formed, and the problem that the workpiece H to be heated is inconvenient to take and place due to the fact that the second air gaps 32 are all arranged on the same horizontal plane is avoided.
By adding a second air gap 32 to each yoke 2, the number of workpieces H to be heated that can be heated simultaneously is increased to 18, which makes full use of the advantage that the superconducting coils can generate large background magnetic field without resistance.
It should be noted that a plurality of second air gaps 32 may be further provided on each parallel yoke 2, so as to accommodate a greater number of workpieces H to be machined. The series-parallel hybrid magnetic circuit formed by the superconducting induction heating device of the embodiment of the application can select an appropriate number of parallel magnetic circuits and an appropriate number of series magnetic circuits according to the process temperature of the workpiece to be heated, the magnetic field value of the air gap background magnetic field, the rotating speed, the magnetic flux of the iron core, the magnetic potential of the superconducting magnet, the rotating speed corresponding to the optimal efficiency of the driving motor, and the like (the number of the series magnetic circuits can be understood as the number of the first air gaps 31 and/or the second air gaps 32 arranged on each closed magnetic circuit).
Referring to fig. 3, fig. 3 is a schematic structural diagram of a superconducting induction heating apparatus according to an embodiment of the present application.
As shown in fig. 3, the superconducting induction heating apparatus of the present application further includes a dewar vessel 4. The Dewar type container can be a container with a single thin-wall structure, the superconducting coil is located in an accommodating cavity of the Dewar type container, vacuumizing treatment is carried out in the container, the outer side of the superconducting coil is wrapped with a plurality of layers of heat insulation materials, and the heat transfer of the container to the outside through transmission, convection and radiation is reduced to the maximum extent through the thin wall, vacuum and the plurality of layers of heat insulation materials.
As an example, the structure of the dewar vessel 4 is shown in fig. 4, and it includes an inner cylinder 41, an outer cylinder 42, and a vacuum chamber between the inner cylinder 41 and the outer cylinder 42, and a superconducting coil is located in the vacuum chamber. The vacuum chamber of the dewar vessel 4 may be formed by vacuum-sealing a space between the inner cylinder 41 and the outer cylinder 42 by an upper cover plate 43 and a lower cover plate (not shown in fig. 4). In the implementation, the Dewar container 4 is of an annular large-caliber single-wall structure, and the inside of the Dewar container is a vacuum environment during working, so that the cold loss generated in conduction, convection and radiation ways is reduced by wrapping a plurality of layers of heat insulating materials on the thin wall, the vacuum and the outside of the magnet.
Referring to fig. 5, fig. 5 is a schematic diagram of a superconducting coil positioned within the vacuum chamber of dewar 4. As shown in fig. 5, the superconducting coil 5 is a superconducting magnet formed by winding a superconducting wire. By way of example, the superconducting coils are preferably arranged to produce a higher magnetic field strength, for example, the configuration of the superconducting coils may be selected from a solenoid coil configuration, which facilitates the formation of a close-wound magnet that facilitates transfer of the cooling circuit in various directions in conduction cooling. In the embodiment, the superconducting coil is impregnated by epoxy resin or paraffin, so that the superconducting coil is beneficial to small overall thermal resistance and convenient for transmission of a cooling circuit in each direction in conduction cooling.
With continued reference to fig. 5, current leads 51 of superconducting coil 5 are disposed on upper cover 43 of dewar vessel 4. The external power supply supplies a large current to superconducting coil 5 through current lead 51. As an example, the current lead 51 is a superconducting current lead, and may be optimized as a segmented superconducting current lead according to heat leakage and joule heat generation to reduce the heat leakage phenomenon. In addition, the current lead 51 may also be a copper lead with a variable cross section to reduce heat leakage.
Further, the superconducting induction heating apparatus of the present application further includes a refrigeration system (not shown in the drawings) that can be used to provide cryogenic cooling to place the superconducting coils in a superconducting state. Specifically, as shown in fig. 4 and 5, a refrigerator cold head 44 is disposed on the upper cover plate 43 of the dewar container 4, and the refrigeration system is connected to the refrigerator cold head 44 and supplies cold energy of low temperature to the vacuum chamber of the dewar container 4 through the refrigerator cold head 44 so as to make the superconducting coil 5 in the vacuum chamber in a superconducting state. As an example, the refrigeration equipment in the refrigeration system of the present embodiment may be a GM refrigerator or a stirling refrigerator.
As described above, the superconducting induction heating apparatus of the present application can form a plurality of series-parallel hybrid magnetic circuits, equally divide the magnetic flux generated by the superconducting coil, fully utilize the advantage of the superconducting strong magnetic field, and increase the magnetic utilization rate of the superconducting coil. Further through increasing the superconductive high-intensity magnetic field utilization ratio, combined with the background magnetic field that has increased the work piece that waits to heat in first air gap, the second air gap, shorten the period of leaking heat that the work piece radiation after the heating and convection produced through adjusting the heating beat, and then the heating beat of positive promotion work piece that waits to heat.
It should be noted that the dewar container 4 and the refrigeration system in the embodiment of the present application are intended to provide a required working environment for the superconducting coil, and those skilled in the art will understand that the dewar container 4 and the refrigeration system may be omitted in the superconducting induction heating apparatus of the present application in the case where there is a working environment suitable for the superconducting coil. In addition, those skilled in the art may also use other devices in place of dewar 4 and refrigeration system, as long as the required working environment can be provided for the present superconducting coil. This is not limited in this application.
In addition, in the present embodiment, the magnitude of the magnetic flux density on the single parallel magnetic circuit can affect the heating power of the workpiece H to be heated. The applicant finds out through experiments that the heating power of the workpiece H to be heated is in positive correlation with the magnetic flux density on a single parallel magnetic circuit. Referring to fig. 6a, fig. 6a is a graph of heating power of a workpiece to be heated versus magnetic flux density on each parallel magnetic circuit. As shown in fig. 6a, the heating power can reach 50W and continuously increase when the magnetic flux density on the single parallel magnetic circuit is 0.65T. Therefore, the present embodiment can enhance the magnetic flux passing through the workpiece to be heated by increasing the magnetic induction, and accordingly provide the heating power of the workpiece to be heated. Therefore, the characteristic that the superconducting magnet can provide higher magnetic induction intensity compared with the traditional permanent magnet can be utilized, so that the time required by heating can be shortened, more heat dissipation is reduced, and the heating characteristic of high efficiency and high utilization rate is realized.
In the present embodiment, the rotation speed of the workpiece to be heated also affects the heating power of the workpiece to be heated H. Typical rotational speed settings may be 120rpm to 3000rpm, which may be specific to superconducting induction heating process requirements. Referring to fig. 6b, fig. 6b is a graph of the heating power of the workpiece to be heated versus the rotational speed of the workpiece to be heated. Wherein, the relationship diagram shown in fig. 6b is a relationship diagram of the heating power of the workpiece to be heated and the rotation speed of the workpiece to be heated under the air gap magnetic field of 0.3T of the superconducting coil. As shown in fig. 6b, the power of the workpiece to be heated reaches a corresponding peak when the rotational speed of the workpiece to be heated is increased to about 2500 rpm. Therefore, in the embodiment, the designed rotation speed of the workpiece to be heated can refer to 2000rpm-2500 rpm.
In summary, in the superconducting induction heating apparatus of the present application, the magnetic conductive core 1 is located at the center of the superconducting coil and performs a magnetic conductive function, and after a current is applied to the superconducting coil, the magnetic conductive core 1 and each parallel yoke form a closed magnetic path channel after the current is applied to the superconducting coil through the plurality of parallel yokes distributed circumferentially around the magnetic conductive core. Furthermore, a first air gap and a second air gap are arranged on each closed magnetic path to place the workpiece H to be heated, the workpiece H to be heated rotates in a background magnetic field generated by the superconducting coil, the magnetic flux in the workpiece to be heated changes due to the non-uniform magnetic field and the rotation of the workpiece to be heated, induced voltage can be generated on the workpiece to be heated according to Lenz's law, induced eddy current is further generated, the eddy current generates heat in the workpiece to be heated, and the workpiece to be heated is heated to the temperature of diathermanous treatment. Thereby realizing the purpose of heating a plurality of workpieces H to be heated simultaneously. In addition, a heating cycle is from the placement of the workpiece to be heated until the workpiece to be heated is heated to the process temperature, and a rapid heating cycle can increase the heating efficiency of the workpiece to be heated. And the superconducting magnet with high magnetic field intensity is beneficial to improving the heating power, so that the heating time is shortened, and the heat loss is reduced. The hybrid magnetic circuit allows the device to have a better regulation function corresponding to the heating process and power.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
It should be noted that in the description of the present specification, the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (7)
1. A hybrid magnetic circuit superconducting induction heating apparatus, characterized in that the superconducting induction heating apparatus comprises:
the magnetic conduction iron core is a columnar iron core, an upper magnetic conduction plate is arranged at the upper end of the magnetic conduction iron core, and a lower magnetic conduction plate is arranged at the lower end of the magnetic conduction iron core;
the superconducting coil surrounds the magnetic core and is connected with an external power supply through a current lead so as to enable the superconducting coil to bear current and further generate a magnetic field; the magnetic conductive iron core is positioned in the center of the superconducting coil;
the superconducting induction heating device further comprises a plurality of parallel iron yokes distributed circumferentially around the magnetic conductive iron core, a first air gap is formed between the upper end face of each iron yoke and the side wall of the upper magnetic conductive plate, and/or a first air gap is also formed between the lower end face of each iron yoke and the side wall of the lower magnetic conductive plate, and the first air gap is used for placing a workpiece to be heated;
after the workpiece to be heated is placed in the first air gap, an external power supply inputs current to the superconducting coil, the magnetic conductive iron core conducts the magnetic field generated by the superconducting coil to a plurality of iron yokes connected in parallel to form a plurality of magnetic circuits connected in parallel, and the workpiece to be heated can rotate under the action of external force to generate induction current to heat the workpiece to be heated;
each iron yoke is also provided with at least one second air gap, the second air gaps on two adjacent iron yokes are arranged in a staggered manner, and the second air gaps are also used for placing a workpiece to be heated; after the magnetic core conducts the magnetic field generated by the superconducting coil to a plurality of parallel iron yokes to form a plurality of parallel magnetic circuits, the workpiece to be heated placed in the second air gap can rotate under the action of external force to generate induction current to heat the workpiece to be heated;
the iron yoke is of a C-shaped structure, and workpieces can be arranged on the upper end face, the lower end face and the middle part of the C-shaped structure; a circular space which is provided with an upper opening and a lower opening and is concentric with the center of a circle of the workpiece to be heated is formed between the upper end surface of each iron yoke and the side wall of the upper magnetic conduction plate; a circular space which is provided with an upper opening and a lower opening and is concentric with the center of a circle of the workpiece to be heated is formed between the lower end surface of each iron yoke and the side wall of the lower magnetic conducting plate;
in the working process, after current is introduced into the superconducting coil, the magnetic conductive iron core and each parallel iron yoke form a closed magnetic path channel so as to heat different workpieces in the first air gap and the second air gap simultaneously.
2. The superconducting induction heating device of claim 1, wherein the plurality of parallel iron yokes are evenly distributed around the magnetically permeable iron core;
and/or the number of the parallel iron yokes is even.
3. The superconducting induction heating apparatus according to claim 1, wherein the superconducting coil is wound using a superconducting wire in a solenoid configuration or a pancake configuration;
and/or the superconducting coil is a superconducting coil impregnated with epoxy resin or paraffin.
4. A superconducting induction heating apparatus according to claim 1, wherein the current lead is a superconducting current lead or a variable-section copper lead;
and/or the columnar iron core is cylindrical.
5. A superconducting induction heating apparatus according to claim 1, characterized in that the rotation speed of the workpiece to be heated is set to 120rpm to 3000 rpm.
6. The superconducting induction heating apparatus according to any one of claims 1 to 5, further comprising a dewar vessel having a housing cavity housing the superconducting coil;
the accommodating cavity can provide a vacuum environment for the superconducting coil.
7. The superconducting induction heating apparatus according to claim 6, further comprising a refrigeration system,
the Dewar type container is provided with a refrigerator cold head, and the refrigerating system is connected with the refrigerator cold head and used for providing low-temperature cold energy for enabling the superconducting coil to be in a superconducting state.
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| CN117574737B (en) * | 2024-01-16 | 2024-03-19 | 河北惠仁医疗设备科技有限公司 | Design method of open type constant magnetic resonance magnet |
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