Electromagnetic stirring device and electron beam melting system

Abstract

The invention discloses an electromagnetic stirring device and an electron beam smelting system.The electromagnetic stirring device comprises an electromagnetic stirrer and a copper smelting pool placed on the electromagnetic stirrer, the electromagnetic stirrer comprises a base, a shielding fence and an electromagnetic coil, the base is horizontally arranged, and the electromagnetic coil is installed in the middle of the upper end of the base; the shielding enclosure is annular and is arranged at the edge of the upper end of the base body, the shielding enclosure and the base body are jointly connected to form a groove shape, the electromagnetic coil is located in the shielding enclosure, the copper smelting pool is placed at the upper end of the shielding enclosure, and the electromagnetic stirrer is used for stirring alloy melt liquid in the copper smelting pool. By arranging the shielding enclosure, a magnetic field generated by the electromagnetic coil can be restrained (the magnetic field is prevented from diffusing towards the periphery), so that the heating electron beam is prevented from deviating, and the energy of the heating electron beam can be more sufficiently used for heating an alloy material in the copper smelting pool.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy melting and stirring, and in particular relates to an electromagnetic stirring device and an electron beam melting system. Background Art

[0002] The electromagnetic stirring magnetic field of the electromagnetic stirring device of the current electron beam melting equipment will cause the trajectory of the heating electron beam to deviate, which will cause the energy of the electron beam to be lost, thereby affecting the heating and melting effect of the alloy material. Summary of the Invention

[0003] In order to solve the above technical problems, one of the objectives of the present invention is to disclose an electromagnetic stirring device with a simple structure, which can optimize the magnetic field strength and constrain the magnetic field to avoid interference with the heating electron beam.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: an electromagnetic stirring device, comprising an electromagnetic stirrer and a copper smelting pool arranged thereon, the electromagnetic stirrer comprising a base body, a shielding enclosure and an electromagnetic coil, the base body being arranged horizontally, the electromagnetic coil being installed in the middle of the upper end of the base body, the shielding enclosure being annular, which is arranged at the edge of the upper end of the base body and is connected with the base body to form a trough shape, and the electromagnetic coil is located in the shielding enclosure, the copper smelting pool is placed at the upper end of the shielding enclosure, and the electromagnetic stirrer is used to stir the molten alloy in the copper smelting pool.

[0005] The beneficial effect of the above technical solution is that by setting a shielding enclosure, the magnetic field generated by the electromagnetic coil can be constrained (to prevent the magnetic field from spreading to the periphery), thereby preventing the heating electron beam from being deflected. In this way, the energy of the heating electron beam can be more fully used to heat the alloy material in the copper smelting pool.

[0006] The electromagnetic coil in the above technical solution includes a main coil and multiple auxiliary coils. The main coil is horizontally arranged in the middle of the base body, and multiple auxiliary coils are vertically arranged on both sides of the main coil.

[0007] The beneficial effect of the above technical solution is that the main coil mainly generates a parallel magnetic field parallel to the bottom of the copper smelting pool, while the secondary coil mainly generates a vertical magnetic field perpendicular to the bottom of the copper smelting pool. The parallel magnetic field generated by the main coil is used to drive horizontal convection of the molten alloy in the copper smelting pool at different depths; and the vertical magnetic field generated by the secondary coil is used to enhance vertical turbulence at the edge, so that the molten alloy in the copper smelting pool can be better and more fully mixed.

[0008] In the above technical solution, four auxiliary coils are provided, two of which are provided on each side of the main coil, and the auxiliary coils on both sides of the main coil are symmetrically distributed, and the four auxiliary coils are distributed in a rectangular shape.

[0009] The beneficial effect of the above technical solution is that the vertical magnetic field applied by the four auxiliary coils causes the alloy melt in the copper smelting pool to generate vertical turbulence, thereby forming a vertical stirring force and improving the ability of the heating electron beam to resist magnetic field interference.

[0010] In the above technical solution, the main coil is a 24-turn double-layer densely wound coil, and the main coil is connected to alternating current; the auxiliary coil is a 5-turn coil, and the auxiliary coil is connected to three-phase alternating current.

[0011] The beneficial effect of the above technical solution is that the magnetic field strengths generated by the main coil and the auxiliary coil can be better coordinated to stir the alloy melt in the copper smelting pool.

[0012] The main coil and the auxiliary coil in the above technical solution are both made of hollow copper tubes coated with aluminum nitride ceramic insulation coating on the outside, and the inside of the tubes is cooled by liquid.

[0013] The beneficial effect of the above technical solution is that the cooling liquid is circulated inside the coil to prevent the coil from deforming due to temperature increase and causing magnetic field distortion.

[0014] In the above technical solution, a cooling channel is provided in the wall of the copper smelting pool, and the liquid inlet and the liquid outlet of the cooling channel both pass through the outer wall of the copper smelting pool.

[0015] The beneficial effect of the above technical solution is that: while the alloy material is heated and melted by the heating electron beam, the coolant is circulated in the cooling channel, thereby preventing the copper smelting pool from being melted through.

[0016] In the above technical solution, a plurality of magnetic gaps are vertically provided on the bottom wall of the copper smelting pool, which are parallel to each other and spaced apart. The magnetic gaps are filled with non-metallic high-temperature resistant spacers.

[0017] The beneficial effect of the above technical solution is that the magnetic field can penetrate into the copper smelting pool through the magnetic gap to stir the alloy melt in the copper smelting pool.

[0018] The high temperature resistant spacer in the above technical solution is a mica sheet or a ceramic sheet.

[0019] The beneficial effect of the above technical solution is that the high-temperature spacer can seal and fill the magnetic gap without melting under the action of the heated electron beam and without introducing impurities into the alloy melt.

[0020] The shielding enclosure described in the above technical solution is a double-layer Permalloy material part.

[0021] The beneficial effect of the above technical solution is that it has a good shielding effect on magnetic fields, especially a good shielding effect on low-frequency or static magnetic fields.

[0022] A second object of the present invention is to provide an electron beam melting system that has a simple structure and good melting effect on alloy materials, and can perform uniform contactless electromagnetic stirring on the alloy materials when they are melted to ensure uniform composition of the alloy materials.

[0023] In order to achieve the above-mentioned object, another technical solution of the present invention is as follows: an electron beam melting system, comprising an electron beam cold hearth melting furnace and the electromagnetic stirring device as described above, wherein the electron beam cold hearth melting furnace is used to heat and melt the alloy material contained in the copper smelting pool.

[0024] The beneficial effect of the above technical solution is that: the electron beam cold hearth melting furnace applies a heating electron beam to the copper smelting pool to heat and melt the alloy material, and the electromagnetic stirring device applies a confined magnetic field from below the copper smelting pool to stir the alloy melt in the copper smelting pool. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an elevation view of the electromagnetic stirring device according to Example 1 of the present invention;

[0026] Figure 2 1 is a perspective view of the electromagnetic stirrer according to embodiment 1 of the present invention;

[0027] Figure 3 Schematic diagram of the pairing of the side walls and the sub-bottom wall of the copper smelting pool in the open state according to Example 1 of the present invention;

[0028] Figure 4 Schematic diagram of the convection of the alloy melt stirred by a parallel magnetic field in a top view of a copper smelting pool in Example 1 of the present invention;

[0029] Figure 5 Schematic diagram of the convection of molten alloy stirred by a vertical magnetic field in a copper smelting pool under test conditions in Example 1 of the present invention;

[0030] Figure 6 This is a schematic structural diagram of the electron beam melting system according to Example 2 of the present invention;

[0031] Figure 7 This is one of the SEM-BSE images of the VNbTaTi alloy in Example 3 of the present invention;

[0032] Figure 8This is the second SEM-BSE image of the VNbTaTi alloy in Example 3 of the present invention.

[0033] In the figure: 1. Electromagnetic stirrer; 11. Base; 12. Shielding enclosure; 13. Electromagnetic coil; 13a. Main coil; 13b. Auxiliary coil; 2. Copper smelting pool; 21. High-temperature resistant spacer; 10. Electromagnetic stirring device; 20. Electron beam cold bed melting furnace. DETAILED DESCRIPTION

[0034] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. The following paragraphs describe the present invention in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in exact proportions. They are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0035] Example 1

[0036] like Figure 1-Figure 3 As shown, this embodiment provides an electromagnetic stirring device, comprising an electromagnetic stirrer 1 and a copper smelting pool 2, the copper smelting pool 2 is placed at the upper end of the electromagnetic stirrer 1, and the electromagnetic stirrer is used to stir the molten alloy in the copper smelting pool. The electromagnetic stirrer 1 comprises a base 11, a shielding enclosure 12 and an electromagnetic coil 13. The base 11 is arranged horizontally, and the electromagnetic coil 13 is installed in the middle of the upper end of the base 11. The shielding enclosure 12 is annular and is arranged at the edge of the upper end of the base 11. It is connected to the base 11 to form a groove shape, and the electromagnetic coil 13 is located in the shielding enclosure 12. The copper smelting pool 2 is placed at the upper end of the shielding enclosure 12. By setting the shielding enclosure, the magnetic field generated by the electromagnetic coil can be constrained (to prevent the magnetic field from spreading to the periphery), thereby preventing the heating electron beam from being offset. In this way, the energy of the heating electron beam can be more fully used to heat the alloy material in the copper smelting pool. The alloy material is placed in a copper smelting pool (the alloy material is heated and stirred to melt).

[0037] like Figure 2 As shown, the electromagnetic coil 13 in the above technical solution includes a main coil 13a and multiple auxiliary coils 13b. The main coil 13a is horizontally arranged in the middle of the base 11, and multiple auxiliary coils 13b are vertically arranged on both sides of the main coil 13a. The main coil mainly generates a parallel magnetic field parallel to the bottom of the copper smelting pool, while the auxiliary coil mainly generates a vertical magnetic field perpendicular to the bottom of the copper smelting pool. The parallel magnetic field of the main coil is used to drive the overall horizontal convection of the alloy melt in the copper smelting pool; and the vertical magnetic field of the auxiliary coil is used to enhance vertical turbulence.

[0038] like Figure 2 As shown, in the above technical solution, four auxiliary coils 13b are provided, two of which are provided on each side of the main coil 13a, and the auxiliary coils 13b on both sides of the main coil 13a are symmetrically distributed, and the four auxiliary coils 13b are distributed in a rectangular shape. In this way, the vertical magnetic field applied by the four auxiliary coils causes the alloy melt in the copper smelting pool to generate edge turbulence, thereby forming a spiral stirring force and improving the ability of the heating electron beam to resist magnetic field interference.

[0039] In the above technical solution, the main coil 13a is a 24-turn double-layer densely wound coil with an outer diameter of 200 mm. The main coil 13a is passed through a 0.1-2 Hz low-frequency alternating current to generate a 1.5 T parallel magnetic field; the auxiliary coil 13b is a 5-turn coil (with an outer diameter of 100 mm and a length of 50 mm). The auxiliary coil 13b is passed through a 2-10 Hz three-phase alternating current to generate a 0.3 T vertical magnetic field.

[0040] In this embodiment, the five electromagnetic coils form a composite magnetic field superposition after being energized. Specifically, the parallel magnetic field (1.5T) of the main coil drives the overall convection of the molten pool (which can also be understood as horizontal convection), which is conducive to improving the temperature distribution of the alloy melt and making it more uniform; the vertical magnetic field (0.3T) of the secondary coil enhances the vertical turbulence, wherein both the parallel magnetic field and the vertical magnetic field form a spiral stirring force (such as Figure 4 and Figure 5 As shown, only the parallel magnetic field drives the swirl of the alloy melt in the horizontal direction, while the vertical magnetic field drives the swirl of the alloy melt in the vertical direction, and the vertical magnetic fields of the four secondary coils act on the four corners inside the copper smelting pool respectively). In addition, the combination of the five electromagnetic coils in this embodiment can form a gradient magnetic field in the copper smelting pool (for the alloy melt, the magnetic field strength gradually increases with increasing depth), which is specifically reflected in the strong magnetic field (0.8 T) at the bottom of the alloy melt and the weak magnetic field (0.1 T) at the top, so that the Lorentz force mainly acts on the middle and lower parts of the copper smelting pool.

[0041] In this embodiment, the central portion of the copper smelting pool is mainly a parallel magnetic field, and the surrounding portion is mainly a vertical magnetic field. At this time, under the coordinated action of the main coil and the auxiliary coil, the alloy melt in the copper smelting pool undergoes sufficient convection both horizontally and vertically, which is conducive to improving the mixing effect of the alloy melt.

[0042] In this embodiment, the low-frequency alternating current of the main coil is set to 0.1-2 Hz, which can avoid harmonic resonance with the scanning frequency of the heating electron beam (usually 50-200 Hz).

[0043] In this embodiment, the shielding enclosure encloses the electromagnetic coil to shield the magnetic field. The magnetic field strength in the heating electron beam path region is ≤0.1mT (well below the offset threshold), while the magnetic field strength on the surface of the copper smelting pool is approximately 0.1mT. This suppresses magnetic field interference, thereby reducing the offset of the heating electron beam to <0.1mm (at 30kV acceleration voltage). The anti-interference strategy in this embodiment is primarily frequency avoidance, where the frequency of the main coil is set to a fraction of the heating electron beam scanning frequency (e.g., 1 / 50), and the frequency of the secondary coil is a non-integer multiple of the heating electron beam scanning frequency (e.g., 7Hz). At the same time, the four secondary coils are orthogonal in phase, i.e., the phases of the four groups of auxiliary coils strictly maintain a 90° difference (error <1°), which makes the distribution of the horizontal rotating magnetic field more uniform.

[0044] The main coil 13a and the auxiliary coil 13 described in the above technical solution, the flow rate of the coolant in the electromagnetic coil in this embodiment can be no less than 2m / s, the flow rate of the main coil coolant can be 20L / min, and the flow rate of the coolant of the auxiliary coil can be 8L / min. The cooling of the electromagnetic coil should be such that the temperature of the electromagnetic coil does not exceed 80°C when in operation.

[0045] In this embodiment, the cross-section of the hollow copper tube is preferably rectangular, so that the electromagnetic coil has a higher density when it is wound.

[0046] In the above technical solution, the wall of the copper smelting pool 2 is provided with a cooling channel, and the liquid inlet and the liquid outlet of the cooling channel both pass through the outer wall of the copper smelting pool 2. In this way, while the heating electron beam heats and melts the alloy material, the coolant can be circulated in the cooling channel, thereby preventing the copper smelting pool from being melted through.

[0047] like Figure 2 and Figure 3 As shown, in the above technical solution, a plurality of mutually parallel and spaced magnetic gaps are vertically penetrated on the bottom wall of the copper smelting pool 2, and the magnetic gaps are filled with non-metallic high-temperature resistant spacers 21, so that the magnetic field can penetrate into the copper smelting pool through the magnetic gaps to stir the alloy melt in the copper smelting pool; the high-temperature resistant spacers 21 are mica sheets or ceramic sheets, so that the high-temperature spacers can seal and fill the magnetic gaps, and at the same time will not melt under the action of the heated electron beam, and will not introduce impurities into the alloy melt.

[0048] like Figure 3As shown, in this embodiment, the base body is square, and the shielding enclosure is frame-shaped. At this time, the shielding enclosure and the base body are connected together to form a square trough body. The copper smelting pool is a square pool body, which can be placed on the upper end of the shielding enclosure and cover the upper end of the shielding enclosure. In this embodiment, there are three magnetic gaps. At this time, the three magnetic gaps divide the bottom wall of the copper smelting pool into four sub-bottom walls. At this time, the side walls on the four sides of the copper smelting pool correspond to the four sub-bottom walls one by one, and each of the side walls and the corresponding sub-bottom wall share a cooling channel (that is, for the entire copper smelting pool, it has four independent cooling channels, and each cooling channel corresponds to a liquid inlet and a liquid outlet). This makes the cooling effect of the entire copper smelting pool good. Figure 3 The four side walls correspond to corresponding sub-bottom walls through double arrows. Specifically, the sub-bottom walls at the ends correspond to the side walls at the corresponding ends, while the two sub-bottom walls in the middle correspond to any of the side walls to their sides. The arrangement of the cooling channels within the copper smelting pool is conventional and will not be described in detail here.

[0049] The shielding enclosure 12 in the above technical solution is a double-layer Permalloy material, which makes it have a good shielding effect on the magnetic field, especially a good shielding effect on the low-frequency or static magnetic field.

[0050] The interior of the base in this embodiment may be a hollow structure and electronic components may be installed therein. The circuit of the electromagnetic stirring device is not described in detail in this embodiment and may be understood as belonging to the prior art.

[0051] Example 2

[0052] like Figure 6 As shown, this embodiment provides an electron beam melting system, including an electron beam cold hearth melting furnace 20 and the electromagnetic stirring device 10 as described in Example 1, wherein the electron beam cold hearth melting furnace 20 is used to heat and melt the alloy material contained in the copper smelting pool 2, so that the electron beam cold hearth melting furnace applies a heating electron beam to the copper smelting pool to heat and melt the alloy material, and the electromagnetic stirring device applies a confined magnetic field from below the copper smelting pool to stir the alloy melt in the copper smelting pool.

[0053] Example 3

[0054] 1. Melt the VNbTaTi alloy.

[0055] 2. The parameters of the electromagnetic stirring device are set as the main coil current of 450A, 2Hz (1.5T), the secondary coil current of 150A, 7Hz (0.3T), the coolant flow rate of the main coil is 25L / min, and the coolant flow rate of the secondary coil is 8L / min.

[0056] 3. Verification results:

[0057] 3.1: The flow rate of the coolant in the copper smelting pool meets the requirements and the temperature is relatively uniform;

[0058] 3.2: The heating electron beam has good stability, and the high-speed camera recording offset is less than 20μm, which does not affect the normal operation of the electron beam cooling hearth melting furnace;

[0059] 3.3: The maximum temperature of the electromagnetic coil does not exceed 85°C, and the deformation is 0.07mm, which meets the requirements;

[0060] 3.4: The quality of the alloy obtained by smelting is good, and the cast alloy shows a typical dendritic structure. This is caused by the difference in melting points between the elements of the alloy. That is, during the non-equilibrium solidification process of the alloy melt, the high-melting-point elements solidify first to form dendrites, and the low-melting-point elements solidify later and are distributed between the dendrites, thus forming a dendritic structure. In this alloy, Ta has the highest melting point and is easy to segregate at the dendrites. The low-melting-point T and V elements segregate between the dendrites, while the distribution of Nb is relatively uniform. Therefore, the SEM-BSE diagram of the cast structure shows that the uniformity of each element is good (for example, Figure 7 and Figure 8 As shown, Figure 5 and Figure 6 All are scanning electron micrographs at 350 times magnification).

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. An electromagnetic stirring device, characterized in that: The invention comprises an electromagnetic stirrer (1) and a copper smelting pool (2) arranged thereon, wherein the electromagnetic stirrer (1) comprises a base (11), a shielding enclosure (12) and an electromagnetic coil (13), wherein the base (11) is arranged horizontally, and the electromagnetic coil (13) is installed in the middle of the upper end of the base (11), and the shielding enclosure (12) is annular and arranged at the edge of the upper end of the base (11) and connected with the base (11) to form a trough shape, and the electromagnetic coil (13) is located in the shielding enclosure (12), and the copper smelting pool (2) is placed at the upper end of the shielding enclosure (12). The electromagnetic stirrer (1) is used to stir the alloy melt in the copper smelting pool (2).

2. The electromagnetic stirring device according to claim 1, characterized in that: The electromagnetic coil (13) comprises a main coil (13a) and a plurality of auxiliary coils (13b); the main coil (13a) is horizontally arranged in the middle of the base (11); and a plurality of auxiliary coils (13b) are vertically arranged on both sides of the main coil (13a).

3. The electromagnetic stirring device according to claim 2, characterized in that: Four auxiliary coils (13b) are provided, two of which are provided on each side of the main coil (13a), and the auxiliary coils (13b) on both sides of the main coil (13a) are symmetrically distributed.

4. The electromagnetic stirring device according to claim 2, characterized in that The main coil (13a) is a double-layer tightly wound coil with 24 turns, and AC power is passed through the main coil (13a); the auxiliary coil (13b) is a coil with 5 turns, and three-phase AC power is passed through the auxiliary coil (13b).

5. The electromagnetic stirring device according to claim 4, characterized in that: The main coil (13a) and the auxiliary coil (13b) are both made of hollow copper tubes coated with an aluminum nitride ceramic insulating coating on the outside, and are cooled by passing liquid inside.

6. The electromagnetic stirring device according to claim 1, characterized in that A cooling channel is provided in the wall of the copper smelting pool (2), and a liquid inlet and a liquid outlet of the cooling channel both penetrate the outer wall of the copper smelting pool (2).

7. The electromagnetic stirring device according to claim 1, characterized in that: A plurality of magnetic gaps are vertically provided on the bottom wall of the copper smelting pool (2) and are parallel to each other and spaced apart. The magnetic gaps are filled with non-metallic high-temperature resistant spacers (21).

8. The electromagnetic stirring device according to claim 7, characterized in that: The high temperature resistant spacer (21) is a mica sheet or a ceramic sheet.

9. The electromagnetic stirring device according to claim 1, characterized in that: The shielding enclosure (12) is a double-layer Permalloy material part.

10. An electron beam melting system, characterized in that: It comprises an electron beam cold hearth melting furnace (20) and an electromagnetic stirring device (10) as claimed in any one of claims 1 to 9, wherein the electron beam cold hearth melting furnace (20) is used to heat and melt the alloy material contained in the copper smelting pool (2).

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