Medium-frequency induction sintering device and method

Abstract

The invention relates to the technical field of sintering furnaces, and discloses a medium-frequency induction sintering device which comprises a furnace body, a mechanical pump and a roots pump, a furnace cover is arranged at the top of the furnace body, and the furnace body is provided with a medium-frequency induction device which comprises a heating coil and a cooling copper pipe; the cooling device is arranged on the furnace cover and comprises a cooling motor and an impeller, and the impeller is arranged on the inner side of the furnace cover; the material supporting device is arranged at the bottom of the furnace body and comprises a liftable heating base, the heating base ascends and descends in the middle of the heating coil, a graphite material box is placed above the heating base, and a samarium cobalt blank is placed in the graphite material box; a furnace cover is opened, a heating base is lifted to an opening of the furnace cover, a graphite material box containing a samarium cobalt blank is placed on the heating base, the heating base descends to move the graphite material box to the middle of a heating coil, sintering is started after the furnace cover is closed, and during sintering, the heating base drives the graphite material box to slide up and down; therefore, the samarium cobalt blank in the graphite material box is heated more uniformly.

Description

Technical Field

[0001] The present invention relates to the technical field of sintering furnaces, and in particular to a medium frequency induction sintering device and method. Background Art

[0002] In modern materials science, samarium cobalt permanent magnets (SmCo) are widely used in a variety of key fields, including aerospace, electronics, and new energy vehicles, thanks to their high magnetic energy product, excellent temperature stability, and corrosion resistance. However, the performance of SmCo permanent magnets depends largely on their sintering process.

[0003] Traditional sintering processes have numerous drawbacks. Uneven heating during the sintering process in conventional sintering furnaces can easily lead to inconsistent internal structures in the samarium-cobalt material, compromising the magnetic consistency of the product and resulting in a high defective rate. Furthermore, during sintering under normal atmospheric conditions, the samarium-cobalt material is susceptible to chemical reactions with oxygen in the air, reducing its purity and performance. Furthermore, some traditional heating methods have slow heating rates, low production efficiency, and high energy consumption, increasing production costs.

[0004] For example, patent publication number CN118352156A discloses a method for rapid sintering of samarium cobalt magnets, which discloses a technical means of sintering samarium cobalt blanks using a medium-frequency induction vacuum sintering furnace. Medium-frequency induction heating is fast, and the vacuum environment can prevent oxidation and reduce the mixing of impurities.

[0005] The existing technology still has the following defects: first, the sintering speed of samarium cobalt is slow and the heating is uneven; second, the operation of adding and removing samarium cobalt blanks into the sintering furnace is inconvenient; finally, the cooling efficiency of samarium cobalt after sintering is low. Summary of the Invention

[0006] (1) Technical problems solved In response to the shortcomings of the existing technology, the present invention provides a medium-frequency induction sintering device, which has the advantages of fast sintering speed, more uniform heating, convenient addition and removal of samarium-cobalt blanks, and fast cooling speed. It solves the problems of slow samarium-cobalt sintering speed and uneven heating, inconvenient addition and removal of samarium-cobalt blanks, and low cooling efficiency in the existing technology.

[0007] (2) Technical solution To achieve the above object, the present invention provides the following technical solutions: A medium frequency induction sintering device comprises a furnace body, a mechanical pump and a Roots pump. A furnace cover is provided on the top of the furnace body. The furnace body is provided with: The medium frequency induction device includes a heating coil and a cooling copper tube. The medium frequency alternating current flows through the heating coil. The heating coil is a hollow structure, and cooling water is passed into the heating coil through the cooling copper tube. A cooling device is provided on the furnace cover and includes a cooling motor and an impeller, wherein the impeller is provided on the inner side of the furnace cover; The supporting device is arranged at the bottom of the furnace body and includes a lifting heating base. The heating base is lifted and lowered in the middle of the heating coil. A graphite material box is placed above the heating base, and the samarium cobalt blank is placed in the graphite material box. After opening the furnace cover, lift the heating base to the opening of the furnace cover, place the graphite box containing the samarium cobalt blank on the heating base, lower the heating base to move the graphite box to the middle of the heating coil, close the furnace cover and start sintering. During sintering, the heating base drives the graphite box to slide up and down, so that the samarium cobalt blank in the graphite box is heated more evenly.

[0008] The top end face of said adjusting base is fixed with a toothed plate, and the bottom end face of said toothed plate is fixed with a toothed plate, and the toothed plate is fixed with a toothed plate at a position equal to or greater than the toothed plate.

[0009] Preferably, the supporting device includes a rotating motor, a support rod and a heating base, the output shaft of the motor is provided with a rotating rod, a spline is provided on the rotating rod, a support rod is slidably connected to the rotating rod, a thread is provided on the outer side of the support rod, and the other end of the support rod is fixed to the heating base, and a support sleeve is also provided in the furnace body, and the support sleeve is connected to the support rod by a thread. When the rotating rod rotates, it drives the support rod to rotate, and when the support rod rotates, it rises and falls under the action of the support sleeve thread, so that the heating base rotates while rotating, thereby improving the heating uniformity.

[0010] Preferably, the graphite material box includes a barrel body, a plurality of horizontal partitions are arranged in the barrel body, the partitions are connected by a central column, end covers are arranged at both ends of the central column at both ends of the barrel body, through holes are arranged on each end cover and the partition, at least one of the two end covers is detachably arranged on the central column, and the partition and the central column can be removed from the barrel body by removing the end cover, so that the samarium cobalt blank can be stored and retrieved from the graphite material box, and the barrel body of the graphite material box and the partitions and end covers are all made of graphite.

[0011] Preferably, the medium frequency induction sintering device further comprises a water tank, which is used to supply cooling water into the cooling copper tube and to cool the mechanical pump and the Roots pump.

[0012] Preferably, the output pipe of the mechanical pump is connected to the input pipe of the Roots pump, the output pipe of the Roots pump is connected to the furnace body, and a main valve is provided in the pipeline from the Roots pump to the furnace body. The medium frequency induction sintering device also includes a medium frequency heating control cabinet, which is used to connect and control the mechanical pump, Roots pump, cooling device, supporting device, medium frequency induction device and main valve. The medium frequency heating control cabinet is also connected to and receives the values ​​detected by the air pressure sensor and temperature sensor arranged in the furnace body.

[0013] Preferably, a plurality of through holes are provided on the heating base, one end of the through hole is connected to the upper surface of the heating base, and the other end is connected to the lower surface of the heating base or the side surface of the heating base.

[0014] Preferably, a limit cover is provided on the support sleeve above the adjustment plate, for limiting the outer side of the adjustment plate to be in a horizontal state at most when the adjustment plate rotates downward.

[0015] Preferably, the impeller includes an air outlet and an air inlet, the air inlet is arranged directly below the middle of the impeller, the air outlet is arranged on the side of the impeller, and the air outlet is inclined downward.

[0016] A medium frequency induction sintering method is also provided, comprising the following steps: S1, open the furnace cover, support the cylinder to push out the heating base, place the graphite material box as a whole on the heating base, and close the furnace cover; S2, start the mechanical pump, open the main valve, when the vacuum degree in the furnace reaches within 1000PA, start the Roots pump until the pressure in the furnace reaches within 0.02PA, close the main valve, and turn off the Roots pump; S3, start the medium frequency induction device to perform medium frequency induction heating, and at the same time control the up and down movement of the heating base to improve heating uniformity, heat to 300 degrees and keep warm for 2 hours, heat to 600 degrees and keep warm for 4 hours, heat to 800 degrees and keep warm for 5 hours, heat to 1000 degrees and keep warm for 1 hour, heat to 1200 degrees and keep warm for 2 hours, cool to 1000 degrees and keep warm for 0.5 hours, finally fill with argon gas to atmospheric pressure and start the cooling device until the product cools to room temperature; S4, the sintering process is completed, the furnace cover is opened, the supporting cylinder pushes out the heating base, and the product is taken out.

[0017] (3) Beneficial effects Compared with the prior art, the present invention provides a medium frequency induction sintering device and method, which has the following beneficial effects: 1. The medium frequency induction sintering device is provided with a medium frequency induction device and a supporting device in the furnace body. The supporting device is used to lift the graphite box. The samarium cobalt blank is placed inside the graphite box. By combining vacuum medium frequency induction with the graphite box, rapid sintering is achieved while ensuring sintering uniformity. At the same time, the liftable heating base can facilitate the removal of the graphite box. Placing the samarium cobalt blank in the graphite box not only utilizes the uniformity of heating the graphite box, but also improves the convenience of placing and removing the samarium cobalt blank before and after sintering, thereby improving the sintering efficiency. A cooling device is also provided in the furnace body to improve the cooling efficiency.

[0018] 2. The medium-frequency induction sintering device is also provided with an adjustment plate inside the furnace body, which is driven to rotate by the lifting of the support rod. The arc of rotation of the adjustment plate is controlled according to the height of the graphite material box. When the graphite material box is at the top, the adjustment plate is in a horizontal state, thereby directing both wind and light to the upper half of the furnace body. When the graphite material box is lowered, the adjustment plate rotates inward, thereby directing both wind and light to the position of the graphite material box, realizing real-time adjustment. The adjustment plate improves the heating efficiency and cooling efficiency.

[0019] 3. The medium frequency induction sintering device replaces the supporting cylinder with a rotating motor. The rotating rod is slidably connected to the supporting rod through a spline, and the outer side of the supporting rod is connected to the supporting sleeve through a threaded connection. The rotating rod drives the supporting rod to rotate and lift at the same time, so that the graphite material box can be lifted and lowered and rotated in the heating coil, thereby improving the sintering uniformity.

[0020] 4. The medium frequency induction sintering device increases the cooling rate of the heating coil by setting the heating coil as a hollow structure and passing cooling water into the heating coil through a cooling copper tube.

[0021] 5. This medium frequency induction sintering method combines vacuum, medium frequency induction and graphite material box into one. The ordinary graphite heating vacuum furnace heats up very slowly, with a heating rate of less than 10℃ / min. The medium frequency induction heating furnace can heat up at a rate of up to 120℃ / min, greatly improving production efficiency.

[0022] 6. This medium frequency induction sintering method requires a lot of insulation materials, such as mullite and molybdenum sheets, in ordinary graphite heating vacuum furnaces. Medium frequency induction heating furnaces do not require insulation materials, saving production costs. Samarium cobalt magnets require a high cooling speed. Under the same working conditions, the cooling time of a graphite sintering furnace with insulation materials is about 1 hour, while the cooling time of a medium frequency induction sintering furnace is about 0.5 hours, which greatly improves product performance.

[0023] 7. In this medium frequency induction sintering method, during the 1200-degree heat preservation process, the supporting device can move up and down at a frequency of 10min / 10cm, which plays a role in uniform sintering and improves the consistency of sintering temperature, thereby ensuring the stability of product performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the present invention.

[0025] Figure 2 It is a structural schematic diagram of the furnace body of the present invention.

[0026] Figure 3 It is a cross-sectional view of the furnace body of the present invention.

[0027] Figure 4 This is a half-cutaway perspective view of the furnace body when the heating base of the present invention is lowered.

[0028] Figure 5 This is a half-cut perspective view of the furnace body when the heating base of the present invention is raised.

[0029] Figure 6 It is a schematic structural diagram of the cooling device of the present invention.

[0030] Figure 7 It is a structural schematic diagram of the supporting device of the present invention.

[0031] Figure 8 It is a schematic structural diagram of the support rod and heating base of the supporting device of the present invention.

[0032] Figure 9 This is a half-cut perspective view of the graphite material box of the present invention.

[0033] Figure 10 A schematic structural diagram of the support rod of the present invention.

[0034] In the figure: 1. furnace body; 2. mechanical pump; 3. Roots pump; 4. water tank; 5. medium frequency heating control cabinet; 6. graphite material box; 7. adjustment plate; 8. samarium cobalt blank; 11. furnace cover; 12. cooling device; 13. supporting device; 14. medium frequency induction device; 15. main valve; 16. support foot; 121. cooling motor; 122. impeller; 1221. air outlet; 1222. air inlet; 131. supporting cylinder; 132. supporting rod; 133. heating base; 134. supporting sleeve; 1331. through hole; 1321. upper section; 1322. middle section; 1323. lower section; 141. heating coil; 142. cooling copper tube; 61. partition; 62. middle column; 63. end cover; 1341. limit cover; 1311. rotating rod. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0037] In addition, a fixed connection refers to a connection in which parts or components are fixed without any relative movement; a transmission connection refers to a connection method in which mechanical motion or torque is transmitted to other working parts through a transmission part; a sliding connection refers to a connection method in which two objects are in contact but not fixed and can slide relative to each other; a rotating connection refers to a connection method in which two objects are in contact but not fixed and can rotate relative to each other.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features being referred to. Thus, features specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0039] Example 1: This embodiment provides a medium frequency induction sintering device having the following technical features.

[0040] See also Figure 1-9 A medium frequency induction sintering device includes a furnace body 1, a mechanical pump 2 and a Roots pump 3. A furnace cover 11 is provided on the top of the furnace body 1. The furnace body 1 is provided with: The intermediate frequency induction device 14 includes a heating coil 141 and a cooling copper tube 142. The heating coil 141 is supplied with intermediate frequency alternating current. The heating coil 141 is a hollow structure, and cooling water is supplied to the heating coil 141 through the cooling copper tube 142. The cooling device 12 is provided on the furnace cover 11 and includes a cooling motor 121 and an impeller 122. The impeller 122 is provided on the inner side of the furnace cover 11. The supporting device 13 is arranged at the bottom of the furnace body 1 and includes a liftable heating base 133. The heating base 133 is made of graphite and is lifted and lowered in the middle position of the heating coil 141. A graphite material box 6 is placed above the heating base 133, and a samarium cobalt blank 8 is placed in the graphite material box 6.

[0041] It should be noted that after opening the furnace cover 11, the heating base 133 is lifted to the opening of the furnace cover 11, and the graphite box 6 containing the samarium cobalt blank 8 is placed on the heating base 133. The heating base 133 is lowered to move the graphite box 6 to the middle of the heating coil 141, and the furnace cover 11 is closed to start sintering. During sintering, the heating base 133 drives the graphite box 6 to slide up and down, so that the samarium cobalt blank 8 in the graphite box 6 is heated more evenly.

[0042] The supporting device 13 is further provided with a supporting cylinder 131, a supporting rod 132 is fixed on the output shaft of the supporting cylinder 131, and a heating base 133 is welded to the other end of the supporting rod 132. A supporting sleeve 134 is also provided on the supporting device 13, and the supporting cylinder 131 is fixed to the outside of the furnace body 1 by bolts. The supporting sleeve 134 is wrapped around the outside of the supporting rod 132 and fixed to the furnace body 1 by bolts. The supporting sleeve 134 is located at one end inside the furnace body 1 and is rotatably connected to a plurality of circumferentially distributed adjusting plates 7. A reflective layer is provided on the upper surface of each adjusting plate 7, and the inner side of the adjusting plate 7 is pressed against the supporting rod 132. The support rod 132 includes an upper section 1321, a middle section 1322 and a lower section 1323. The outer diameter of the upper section 1321 is larger than the outer diameter of the lower section 1323. The middle section 1322 is a connecting surface connecting the upper section 1321 and the lower section 1323. When the support rod 132 moves upward, it drives the inner side of the adjustment plate 7 to rotate upward, so that the outer main body of the adjustment plate 7 rotates downward. When the support rod 132 moves downward, it drives the inner side of the adjustment plate 7 to rotate downward, so that the outer main body of the adjustment plate 7 rotates upward. The adjustment plate 7 acts as a reflector and windshield to guide light and airflow to the graphite material box 6 at different heights.

[0043] It should be noted that the connection between the output shaft and the support rod 132 is one of integrated, welded, threaded or bolted. The reflective layer can be tungsten and tungsten alloys. Tungsten and tungsten alloys have good metallic luster and reflective properties. After fine processing and surface treatment, high reflectivity can be obtained, which can effectively reflect light and heat in high temperature environments. Or it can be a ceramic-based composite material. By coating a reflective coating on its surface or adopting a special fiber layup design, a good reflective effect can be achieved, which can effectively reflect light and heat in high temperature environments.

[0044] It is further provided that the graphite material box 6 includes a barrel body, and five horizontal partitions 61 are arranged in the barrel body. The partitions 61 are connected by a central column 62, and end covers 63 are arranged at both ends of the central column 62 at both ends of the barrel body. Through holes are provided on each end cover 63 and the partition 61, and at least one of the two end covers 63 is detachably arranged on the central column 62. By removing the end cover 63, the partition 61 and the central column 62 can be taken out of the barrel body, thereby taking the samarium cobalt blank 8 out of the graphite material box 6. The barrel body of the graphite material box 6 and the materials of each partition 61 and the end cover 63 are all graphite.

[0045] It should be noted that the partition plate 61 and the center column 62 are an integrated structure, and the end cover 63 and the center column 62 are fixedly connected by bolts.

[0046] It is further provided that the medium frequency induction sintering device further includes a water tank 4 .

[0047] It should be noted that the water tank 4 is used to supply cooling water into the cooling copper tube 142 and to cool the mechanical pump 2 and the Roots pump 3 .

[0048] It is further provided that the output pipe of the mechanical pump 2 is connected to the input pipe of the Roots pump 3, the output pipe of the Roots pump 3 is connected to the furnace body 1, and a main valve 15 is provided in the pipeline from the Roots pump 3 to the furnace body 1. The medium frequency induction sintering device also includes a medium frequency heating control cabinet 5, which is used to connect and control the mechanical pump 2, the Roots pump 3, the cooling device 12, the supporting device 13, the medium frequency induction device 14 and the main valve 15.

[0049] It should be noted that the medium frequency heating control cabinet 5 is also connected to and receives the values ​​detected by the air pressure sensor and the temperature sensor arranged in the furnace body 1 .

[0050] Furthermore, a plurality of through holes 1331 are provided on the heating base 133 , one end of the through hole 1331 is connected to the upper surface of the heating base 133 , and the other end is connected to the lower surface of the heating base 133 or the side surface of the heating base 133 .

[0051] Furthermore, a limit cover 1341 is provided on the support sleeve 134 above the adjustment plate 7 for limiting the outer side of the adjustment plate 7 to be in a horizontal state at most when the adjustment plate 7 rotates downward.

[0052] It should be noted that the limiting cover 1341 and the supporting sleeve 134 are integrally connected or welded together.

[0053] It is further provided that the impeller 122 includes an air outlet 1221 and an air inlet 1222 , the air inlet 1222 is provided just below the center of the impeller 122 , the air outlet 1221 is provided on the side of the impeller 122 , and the air outlet 1221 is tilted downward.

[0054] Furthermore, three supporting legs 16 distributed in a circumference are provided on the outer bottom of the furnace body 1 .

[0055] Example 2: This embodiment provides a medium frequency induction sintering device having the following technical features.

[0056] See also Figure 1-9 A medium frequency induction sintering device includes a furnace body 1, a mechanical pump 2 and a Roots pump 3. A furnace cover 11 is provided on the top of the furnace body 1. The furnace body 1 is provided with: The intermediate frequency induction device 14 includes a heating coil 141 and a cooling copper tube 142. The heating coil 141 is supplied with intermediate frequency alternating current. The heating coil 141 is a hollow structure, and cooling water is supplied to the heating coil 141 through the cooling copper tube 142. The cooling device 12 is provided on the furnace cover 11 and includes a cooling motor 121 and an impeller 122. The impeller 122 is provided on the inner side of the furnace cover 11. The supporting device 13 is arranged at the bottom of the furnace body 1 and includes a liftable heating base 133. The heating base 133 is lifted and lowered in the middle position of the heating coil 141. A graphite material box 6 is placed above the heating base 133, and a samarium cobalt blank 8 is placed in the graphite material box 6.

[0057] See also Figure 10 The supporting device 13 includes a rotating motor, a support rod 132 and a heating base 133. The output shaft of the motor is provided with a rotating rod 1311. A spline is provided on the rotating rod 1311. The rotating rod 1311 is slidably connected to the support rod 132. A thread is provided on the outer side of the support rod 132. The other end of the support rod 132 is fixed to the heating base 133. A supporting sleeve 134 is also provided in the furnace body 1. The support sleeve 134 is connected to the support rod 132 by a thread. When the rotating rod 1311 rotates, it drives the support rod 132 to rotate. When the support rod 132 rotates, it rises and falls under the action of the thread of the support sleeve 134, so that the heating base 133 rotates while rotating, thereby improving the uniformity of heating.

[0058] Example 3: This embodiment provides a medium frequency induction sintering method having the following technical features.

[0059] A medium frequency induction sintering method comprises the following steps: S1, open the furnace cover 11, support the cylinder 131 to push out the heating base 133, place the graphite material box 6 as a whole on the heating base 133, and close the furnace cover 11; S2, start the mechanical pump 2, open the main valve 15, when the vacuum degree in the furnace reaches within 1000PA, start the Roots pump 3 until the pressure in the furnace reaches within 0.02PA, close the main valve 15, and turn off the Roots pump 3; S3, start the medium frequency induction device 14 to perform medium frequency induction heating, and at the same time control the heating base 133 to move up and down to improve heating uniformity, heat to 300 degrees and keep warm for 2 hours, heat to 600 degrees and keep warm for 4 hours, heat to 800 degrees and keep warm for 5 hours, heat to 1000 degrees and keep warm for 1 hour, heat to 1200 degrees and keep warm for 2 hours, cool to 1000 degrees and keep warm for 0.5 hours, finally fill with argon gas to atmospheric pressure and start the cooling device 12 until the product cools to room temperature; S4, the sintering process is completed, the furnace cover 11 is opened, the supporting cylinder 131 pushes out the heating base 133, and the product is taken out.

[0060] Example 4: This embodiment provides a medium frequency induction sintering method having the following technical features.

[0061] A medium frequency induction sintering method comprises the following steps: (1) Melting: Weigh (5.0-25.0)% Fe, (4.0-8.0)% Cu, (36.0-65.0)% Co, (2.0-4.0)% Zr and (24.0-27.0)% Sm by weight and place them in a vacuum melting furnace; Evacuate the vacuum melting furnace and fill it with protective gas; Heat the melt to a temperature between (1450-1550)°C and continue refining for (2-5) minutes to obtain a uniform alloy melt; (2) Ingot casting: The alloy melt is poured into a cooling mold or onto a rapidly rotating copper roller for cooling to obtain an ingot or a strip; (3) Powdering: After the ingot or the spinning belt is coarsely crushed, it is conveyed to the air flow mill for powdering, and the surface average particle size of the particles is controlled between (3.0-5.0) μm to obtain sintered samarium cobalt material powder; (4) Molding: Orientation is carried out in a magnetic field, and inert gas is filled for protection during the pressing process. After molding, the pressure is maintained in a cold isostatic press at (200-280) MPa for (1-5) minutes; (5) Sintering and aging: The blank after isostatic pressing is placed in a medium frequency induction furnace. The blank is placed with a special tooling and vacuumed to below 0.1Pa. The medium frequency is adjusted to (30-50)kW. After (1-5)min, the temperature is reduced to (20-30)kW for insulation. The insulation time is (0.1-2)h. Then the frequency is reduced to (10-15)kW for solid solution insulation for (0.1-2)h. After the process is completed, it is quickly cooled to below 80℃, and then transferred to the aging furnace. The temperature is quickly increased to the aging temperature at (2-10)℃ / min for aging. After the aging is completed, the samarium cobalt magnet is obtained.

[0062] It is further provided that, in step (1), the order of adding materials is Fe-Cu-Co-Zr-Sm.

[0063] It is further provided that, in step (1), when the vacuum degree of the vacuum melting furnace is evacuated to be less than or equal to 1 Pa, an inert gas is then filled into the vacuum melting furnace to maintain the vacuum degree between (-0.1 and -0.04) MPa.

[0064] It is further provided that, in step (3), the oxygen content in the air flow mill is set to be lower than 100 ppm, and the grinding pressure is set to (0.4-0.7) MPa.

[0065] Furthermore, in step (4), the molding pressure is set to (10-40) MPa, the magnetizing current is set to (2000-3000) A, and the demagnetizing current is set to (800-1500) A.

[0066] It is further provided that, in step (5), the shape of the blank tooling is rectangular or cylindrical, and the interior of the tooling is separated by high temperature resistant material.

[0067] It is further provided that the high temperature resistant material is made of high temperature resistant stainless steel, carbon-carbon, silicon carbide or ceramic.

[0068] It is further provided that, in step (5), the sintering power of the medium frequency induction furnace is (30-50) kW, the frequency is (0.8-2) kHz, and the insulation power is (20-30) kW.

[0069] It is further provided that, in step (5), when cooling to the solution temperature, the power of the medium frequency induction furnace is set to (10-15) kW.

[0070] It is further provided that, in step (5), a rapid cooling fan is used on the top or side of the medium frequency induction furnace for sintering to control the cooling rate.

[0071] Furthermore, during the aging process at (800-850)°C for (6-25) h, argon 50 kPa was filled at 500°C. After the aging was completed, the magnetic properties were tested.

[0072] Beneficial effects: This method goes through the processes of smelting, ingot casting, powder making, molding, sintering, and aging. As the sintering time increases, the density of the magnet increases. By 60 minutes, the magnet is already dense (density requirement: 8.35-8.4g / cm3). In a conventional sintering furnace, the density is only 7.21g / cm3 after sintering for 30 minutes. After the time is increased to 150 minutes, the density increases to 8.36g / cm3. In contrast, after the blank is formed, the present invention enters a medium-frequency induction furnace for high-temperature sintering. Since the medium-frequency induction furnace uses a medium-frequency magnetic field to generate eddy currents inside the material for heating, it heats up quickly, the temperature inside the material is relatively uniform, and the temperature is easy to control. The sintering time of the medium-frequency induction furnace of the present invention is shortened by 90 minutes, which greatly shortens the manufacturing cycle and improves production efficiency.

[0073] To sum up, the medium frequency induction sintering device is provided with a medium frequency induction device 14 and a supporting device 13 in the furnace body 1. The supporting device 13 is used to lift the graphite box 6, and the samarium cobalt blank 8 is placed inside the graphite box 6. By combining vacuum medium frequency induction with the graphite box, rapid sintering is achieved while ensuring sintering uniformity. At the same time, the liftable heating base 133 can facilitate the taking of the graphite box 6. Placing the samarium cobalt blank 8 in the graphite box 6 not only utilizes the uniformity of heating of the graphite box 6, but also improves the convenience of placing and removing the samarium cobalt blank 8 before and after sintering, thereby improving the sintering efficiency. By also arranging a cooling device 12 in the furnace body 1, the cooling efficiency is improved.

[0074] The medium frequency induction sintering device is further provided with an adjustment plate 7 in the furnace body 1, which is driven to rotate by the support rod 132. The arc of rotation of the adjustment plate 7 is controlled according to the height of the graphite material box 6. When the graphite material box 6 is at the top, the adjustment plate 7 is in a horizontal state, thereby guiding both wind and light to the upper half of the furnace body 1. When the graphite material box 6 descends, the adjustment plate 7 rotates inward, thereby guiding both wind and light to the position of the graphite material box 6, realizing real-time adjustment. The adjustment plate 7 improves the heating efficiency and cooling efficiency.

[0075] In this medium frequency induction sintering device, the support cylinder 131 is replaced with a rotating motor. The rotating rod 1311 is slidingly connected to the support rod 132 via a spline, and the outer side of the support rod 132 is connected to the support sleeve 134 via a threaded connection, so that the rotating rod 1311 drives the support rod 132 to rotate and lift at the same time, so that the graphite material box 6 can be lifted and lowered and rotated in the heating coil 141, thereby improving the sintering uniformity.

[0076] The medium frequency induction sintering device increases the cooling rate of the heating coil 141 by setting the heating coil 141 as a hollow structure and introducing cooling water into the heating coil 141 through the cooling copper tube 142.

[0077] This medium frequency induction sintering method combines vacuum, medium frequency induction and graphite material box into one. Ordinary graphite heating vacuum furnace heats up very slowly, with a heating rate of less than 10℃ / min, while the medium frequency induction heating furnace can heat up at a rate of up to 120℃ / min, greatly improving production efficiency.

[0078] In this medium frequency induction sintering method, ordinary graphite heating vacuum furnaces require a lot of insulation materials, such as mullite and molybdenum sheets, while medium frequency induction heating furnaces do not require insulation materials, saving production costs. Samarium cobalt magnets require a very fast cooling speed. Under the same working conditions, the cooling time of a graphite sintering furnace with insulation materials is about 1 hour, while the cooling time of a medium frequency induction sintering furnace is about 0.5 hours, which greatly improves product performance.

[0079] In this medium frequency induction sintering method, during the 1200 degree heat preservation process, the supporting device 13 can move up and down at a frequency of 10min / 10cm, which achieves uniform sintering and improves the consistency of sintering temperature, thereby ensuring the stability of product performance.

[0080] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0081] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A medium frequency induction sintering device, comprising a furnace body (1), a mechanical pump (2) and a Roots pump (3), characterized in that: A furnace cover (11) is provided on the top of the furnace body (1), and the furnace body (1) is provided with: A medium-frequency induction device (14) includes a heating coil (141) and a cooling copper tube (142), wherein medium-frequency alternating current flows through the heating coil (141), the heating coil (141) is a hollow structure, and cooling water flows into the heating coil (141) through the cooling copper tube (142); A cooling device (12) is provided on the furnace cover (11), comprising a cooling motor (121) and an impeller (122), wherein the impeller (122) is provided inside the furnace cover (11); A supporting device (13) is provided at the bottom of the furnace body (1), and includes a liftable heating base (133). The heating base (133) is lifted and lowered in the middle of the heating coil (141). A graphite material box (6) is placed above the heating base (133), and a samarium cobalt blank (8) is placed in the graphite material box (6). After opening the furnace cover (11), the heating base (133) is lifted to the opening of the furnace cover (11), and the graphite box (6) containing the samarium cobalt blank (8) is placed on the heating base (133). The heating base (133) is lowered to move the graphite box (6) to the middle of the heating coil (141), and the furnace cover (11) is closed to start sintering. During sintering, the heating base (133) drives the graphite box (6) to slide up and down, so that the samarium cobalt blank (8) in the graphite box (6) is heated more evenly.

2. A medium frequency induction sintering device according to claim 1, characterized in that: The supporting device (13) includes a supporting cylinder (131), a supporting rod (132) is fixed on the output shaft of the supporting cylinder (131), and the other end of the supporting rod (132) is fixed to the heating base (133). The supporting device (13) is also provided with a supporting sleeve (134), the supporting cylinder (131) is fixed on the outside of the furnace body (1), the supporting sleeve (134) is wrapped around the outside of the supporting rod (132) and fixed on the furnace body (1), and the supporting sleeve (134) is located in the furnace body (1) and is rotatably connected to a plurality of circumferentially distributed adjusting plates (7), each adjusting plate (7) is provided with a reflective layer on its upper surface, and the inner side of the adjusting plate (7) is pressed against the supporting rod (132). The support rod (132) includes an upper section (1321), a middle section (1322) and a lower section (1323). The outer diameter of the upper section (1321) is larger than the outer diameter of the lower section (1323). The middle section (1322) is a connecting surface connecting the upper section (1321) and the lower section (1323). When the support rod (132) moves upward, it drives the inner side of the adjustment plate (7) to rotate upward, so that the outer main body of the adjustment plate (7) rotates downward. When the support rod (132) moves downward, it drives the inner side of the adjustment plate (7) to rotate downward, so that the outer main body of the adjustment plate (7) rotates upward. The adjustment plate (7) serves as a reflector and a windshield to guide light and airflow to the graphite material boxes (6) at different heights.

3. The medium frequency induction sintering device according to claim 1, characterized in that: The supporting device (13) includes a rotating motor, a support rod (132) and a heating base (133). The output shaft of the motor is provided with a rotating rod (1311). A spline is provided on the rotating rod (1311). The rotating rod (1311) is slidably connected to the supporting rod (132). The outer side of the supporting rod (132) is provided with a thread. The other end of the supporting rod (132) is fixed to the heating base (133). A supporting sleeve (134) is also provided in the furnace body (1). The supporting sleeve (134) is connected to the supporting rod (132) by a thread. When the rotating rod (1311) rotates, the supporting rod (132) is driven to rotate. When the supporting rod (132) rotates, it rises and falls under the action of the thread of the supporting sleeve (134), so that the heating base (133) rotates while rotating, thereby improving the heating uniformity.

4. A medium frequency induction sintering device according to claim 2, characterized in that: The graphite material box (6) includes a barrel body, wherein a plurality of horizontal partitions (61) are arranged in the barrel body, and each partition (61) is connected by a central column (62). End covers (63) are arranged at both ends of the central column (62) at both ends of the barrel body, and through holes are arranged on each end cover (63) and the partition (61). At least one of the two end covers (63) is detachably arranged on the central column (62). By removing the end cover (63), the partition (61) and the central column (62) can be taken out of the barrel body, thereby taking the samarium cobalt blank (8) out of the graphite material box (6). The barrel body of the graphite material box (6) and each partition (61) and the end cover (63) are all made of graphite.

5. The medium frequency induction sintering device according to claim 1, characterized in that: The medium frequency induction sintering device further comprises a water tank (4), which is used to introduce cooling water into the cooling copper tube (142) and to cool the mechanical pump (2) and the Roots pump (3).

6. The medium frequency induction sintering device according to claim 1, characterized in that: The output pipe of the mechanical pump (2) is connected to the input pipe of the Roots pump (3), and the output pipe of the Roots pump (3) is connected to the furnace body (1). A main valve (15) is provided in the pipeline from the Roots pump (3) to the furnace body (1). The medium-frequency induction sintering device also includes a medium-frequency heating control cabinet (5) for connecting and controlling the mechanical pump (2), the Roots pump (3), the cooling device (12), the supporting device (13), the medium-frequency induction device (14) and the main valve (15). The medium-frequency heating control cabinet (5) is also connected to and receives values ​​detected by an air pressure sensor and a temperature sensor provided in the furnace body (1).

7. The medium frequency induction sintering device according to claim 1, characterized in that: A plurality of through holes (1331) are provided on the heating base (133), one end of the through hole (1331) is connected to the upper surface of the heating base (133), and the other end is connected to the lower surface of the heating base (133) or the side surface of the heating base (133).

8. The medium frequency induction sintering device according to claim 2, characterized in that: A limiting cover (1341) is provided on the support sleeve (134) above the adjustment plate (7) for limiting the outer side of the adjustment plate (7) to a horizontal state at most when the adjustment plate (7) rotates downward.

9. The medium frequency induction sintering device according to claim 1, characterized in that: The impeller (122) comprises an air outlet (1221) and an air inlet (1222), wherein the air inlet (1222) is arranged directly below the middle of the impeller (122), and the air outlet (1221) is arranged on the side of the impeller (122), and the air outlet (1221) is tilted downward.

10. A medium frequency induction sintering method, using the medium frequency induction sintering device according to any one of claims 1 to 9 for sintering, characterized in that: The following steps are involved: S1, open the furnace cover (11), support the cylinder (131) to push out the heating base (133), place the graphite material box (6) as a whole on the heating base (133), and close the furnace cover (11); S2, start the mechanical pump (2), open the main valve (15), when the vacuum degree in the furnace reaches within 1000PA, start the Roots pump (3) until the pressure in the furnace reaches within 0.02PA, close the main valve (15), and turn off the Roots pump (3); S3, start the medium frequency induction device (14) to perform medium frequency induction heating, and at the same time control the heating base (133) to move up and down to improve the heating uniformity, heat to 300 degrees and keep warm for 2 hours, heat to 600 degrees and keep warm for 4 hours, heat to 800 degrees and keep warm for 5 hours, heat to 1000 degrees and keep warm for 1 hour, heat to 1200 degrees and keep warm for 2 hours, cool to 1000 degrees and keep warm for 0.5 hours, finally fill with argon gas to atmospheric pressure and start the cooling device (12) until the product cools to room temperature; S4, the sintering process is completed, the furnace cover (11) is opened, the supporting cylinder (131) pushes out the heating base (133), and the product is taken out.

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