A high-coercivity neodymium-iron-boron magnet preparation system and method

Abstract

The application discloses a high-coercivity neodymium-iron-boron magnet preparation system and method, and relates to the technical field of material preparation. The system comprises a transition bin, a first vacuum film coating bin, a magnet turning bin, a second vacuum film coating bin, a vacuum diffusion bin and a rapid cooling bin which are sequentially connected. Automatic conveying rollers are arranged in all the bins. Adjacent two bins are connected through vacuum pipes. Gate valves are arranged on the vacuum pipes connecting the transition bin and the first vacuum film coating bin, the second vacuum film coating bin and the vacuum diffusion bin, and the vacuum diffusion bin and the rapid cooling bin. Vacuum pumping units and air mixing valves are arranged in all the bins. The transition bin and the rapid cooling bin are further provided with air release valves. The two process modules of vacuum film coating and vacuum grain boundary diffusion are integrated, and high-coercivity and high-performance neodymium-iron-boron magnet material can be efficiently and large-scaled prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and more particularly to a system and method for preparing a high-coercivity neodymium iron boron magnet. Background Art

[0002] The heavy rare earth grain boundary diffusion technology of NdFeB magnets refers to coating a layer of heavy rare earth diffusion source material on the surface of NdFeB magnets, and then subjecting the magnets to vacuum diffusion treatment to allow heavy rare earth atoms to penetrate into the magnets along the grain boundaries. 14 A heavy rare earth-rich shell with a higher magnetocrystalline anisotropy field forms on the shallow surface of the B main phase grains, achieving the goal of significantly improving the intrinsic coercivity of the magnet with a small amount of heavy rare earth. Although the heavy rare earth grain boundary diffusion technology for NdFeB magnets has been around for less than 20 years, its development and large-scale application have been extremely rapid. At this stage, it has basically become an essential means of preparing high-performance NdFeB magnets. Currently, the most widely used technical route for industrial application of heavy rare earth grain boundary diffusion in NdFeB magnets is to first use magnetron sputtering coating equipment to coat the front and back of the NdFeB magnets with heavy rare earth dysprosium or terbium. After removing the magnets, they are turned over in an atmospheric environment and then sent to a vacuum magnetron sputtering coating equipment for a second time to coat the back of the magnets with heavy rare earth. After being removed from the furnace, they are then loaded into a vacuum diffusion furnace in batches for high-temperature diffusion treatment, which involves multiple processes such as vacuuming, heating, insulation, and cooling. On the one hand, repeated exposure of heavy rare earth-coated NdFeB magnets to the atmosphere can lead to slight oxidation of the coating due to the absorption of oxygen and moisture. On the other hand, the high-temperature grain boundary diffusion of heavy rare earths in batches requires repeated vacuuming, heating, and cooling, which is not only extremely inefficient but also wastes energy. Therefore, integrating the heavy rare earth vacuum coating and vacuum diffusion processes into a continuous production line has extremely important economic and social significance.

[0003] Therefore, how to integrate the production line of high coercivity NdFeB magnets, improve the preparation effect and efficiency, and reduce energy waste is an urgent problem that technicians in this field need to solve. Summary of the Invention

[0004] In view of this, the present invention provides a system and method for preparing high coercive force NdFeB magnets. It is an overall industrialized continuous production system that uses grain boundary diffusion technology to increase the intrinsic coercive force of NdFeB magnets. It can effectively improve the preparation effect and production efficiency of high coercive force NdFeB magnets and reduce energy waste.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A high-coercivity NdFeB magnet preparation system comprises a transition chamber, a first vacuum coating chamber, a magnet turning chamber, a second vacuum coating chamber, a vacuum diffusion chamber and a rapid cooling chamber, which are connected in sequence. Automatic conveying rollers are provided in all chambers, and adjacent chambers are connected by vacuum pipes. Gate valves are provided on the vacuum pipes connecting the transition chamber and the first vacuum coating chamber, the second vacuum coating chamber and the vacuum diffusion chamber, and the vacuum diffusion chamber and the rapid cooling chamber. All chambers are equipped with vacuum pumping units and aeration valves. The transition chamber and the rapid cooling chamber are also equipped with air release valves.

[0007] Preferably, the NdFeB magnets to be processed are placed on a workpiece tray, which moves on automatic conveying rollers. The automatic conveying rollers of two adjacent bins are brought close together to transfer the workpiece tray from one bin to another.

[0008] Preferably, a flap valve is provided at one end of the transition chamber away from the first vacuum coating chamber, and the NdFeB magnet to be processed is placed by opening the flap valve.

[0009] Preferably, the first vacuum coating chamber and the second vacuum coating chamber are provided with magnetron sputtering targets above the automatic conveying roller.

[0010] Preferably, a magnet flipping mechanism is provided in the magnet flipping bin, and an electromagnetic chuck can be used as the magnet flipping mechanism to grab the NdFeB magnet to be processed and flip it over; or a double workpiece disk with one empty disk and one full disk can be used to flip the NdFeB magnet.

[0011] Preferably, the vacuum diffusion chamber is provided with an electrically connected temperature controller and an electrically heated molybdenum belt above the automatic conveying roller, and a heat insulation screen is provided on the inner wall of the chamber.

[0012] Preferably, a flap valve is provided at one end of the rapid cooling chamber principle vacuum diffusion chamber, and the prepared high coercive force NdFeB magnet is taken out by opening the flap valve.

[0013] Preferably, the aeration valves of the transition chamber, the first vacuum coating chamber, the magnet turning chamber, the second vacuum coating chamber and the vacuum diffusion chamber are connected to the argon source, and the aeration valve of the rapid cooling chamber is connected to the liquid nitrogen source.

[0014] Preferably, the aeration valve is connected to a mass flow meter for monitoring the amount of argon or liquid nitrogen introduced and regulating the opening of the aeration valve.

[0015] Preferably, the magnetron sputtering target can be sputtered and coated with heavy rare earth target, light rare earth target or other metal target, and the thin film formed by coating on the surface of the NdFeB magnet to be processed includes heavy rare earth film, light rare earth film or other metal film.

[0016] Preferably, a photoelectric position sensor is provided in each bin body to detect the occupancy status of each workpiece disc on the automatic conveying roller, thereby realizing queuing control of multiple workpiece discs.

[0017] A method for preparing a high coercive force NdFeB magnet, based on the above-mentioned preparation system, comprises the following steps:

[0018] Step 1: Close all valves, start the vacuum pumping unit, and evacuate the transition chamber, the first vacuum coating chamber, the magnet turning chamber, the second vacuum coating chamber, the vacuum diffusion chamber, and the rapid cooling chamber to a high vacuum state;

[0019] Step 2: Heat the vacuum diffusion chamber to the preparation temperature;

[0020] Step 3: Open the gas injection valve to fill high-purity argon gas into the first vacuum coating chamber, the magnet turning chamber, and the second vacuum coating chamber, so that the first vacuum coating chamber, the magnet turning chamber, and the second vacuum coating chamber are maintained in a low vacuum state; start the sputtering of heavy rare earth particle beams in the first vacuum coating chamber and the second vacuum coating chamber;

[0021] Step 4: Turn off the vacuum pumping unit of the transition chamber and open the air release valve of the transition chamber until the air pressure in the transition chamber reaches atmospheric pressure and then close the air release valve. Place the NdFeB magnets to be processed into the transition chamber and then turn on the vacuum pumping unit to restore the air pressure in the transition chamber to a high vacuum state. Open the aeration valve of the transition chamber and introduce high-purity argon gas to maintain the air pressure in the transition chamber at a low vacuum state.

[0022] Step 5: Open the gate valve between the transition chamber and the first vacuum coating chamber, transfer the NdFeB magnets to be processed to the first vacuum coating chamber via the automatic conveyor roller, and close the gate valve;

[0023] Step 6: The first vacuum coating chamber sputters a layer of coating on the upper surface of the NdFeB magnet to be processed, and the NdFeB magnet to be processed is transferred to the magnet turning chamber by an automatic conveyor roller. The magnet turning chamber turns the NdFeB magnet to be processed over and then transfers it to the second vacuum coating chamber by an automatic conveyor roller. The second vacuum coating chamber sputters a layer of coating on the lower surface of the NdFeB magnet to be processed;

[0024] Step 7: Open the aeration valve of the vacuum diffusion chamber, introduce high-purity argon gas, maintain the vacuum diffusion chamber in a low vacuum state, open the gate valve between the second vacuum coating chamber and the vacuum diffusion chamber, transfer the NdFeB magnets to be processed to the vacuum diffusion chamber via the automatic conveyor roller, and close the gate valve; close the aeration valve of the vacuum diffusion chamber, open the vacuum pumping unit of the vacuum diffusion chamber, restore the vacuum diffusion chamber to a high vacuum state, heat the NdFeB magnets to be processed, and after heating is completed, open the gate valve between the vacuum diffusion chamber and the rapid cooling chamber, transfer the NdFeB magnets to be processed to the rapid cooling chamber via the automatic conveyor roller, and close the gate valve;

[0025] Step 8: Open the aeration valve of the rapid cooling chamber and introduce low-temperature gas. After the NdFeB magnets to be processed are cooled to room temperature, close the vacuum pumping unit of the rapid cooling chamber and open the air release valve. After taking out the prepared high coercive force NdFeB magnets, close the air release valve of the rapid cooling chamber and open the vacuum pumping unit to restore the rapid cooling chamber to a high vacuum state.

[0026] Through the above technical solution, it can be seen that compared with the existing technology, the present invention discloses a high coercive force NdFeB magnet preparation system and method, which integrates the two process modules of vacuum coating and vacuum grain boundary diffusion. The system completes the vacuum coating and grain boundary diffusion of heavy rare earth (or light rare earth or other metal elements) diffusion source materials on the surface of NdFeB magnets in a continuous production mode, so as to achieve the purpose of improving the intrinsic coercive force of the magnet. It has the advantages of precise control of the infiltration amount of diffusion source materials, integrated integration of vacuum coating and vacuum diffusion, low energy consumption and zero emissions in the production process, and good product quality consistency. It is an effective means for large-scale preparation of high coercive force and high-performance NdFeB magnetic materials. Specific beneficial effects include:

[0027] (1) The vacuum coating process and the vacuum diffusion process are integrated into a continuous production line, which reduces the adverse effects of exposure of the intermediate workpiece to the atmospheric environment on magnet preparation;

[0028] (2) There is no need to repeatedly perform vacuuming and heating and cooling processes, which can effectively reduce energy consumption and improve production efficiency;

[0029] (3) The assembly line production model helps to improve the consistency of the quality of high-performance NdFeB magnets. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0031] Figure 1 This is a schematic structural diagram of the high coercivity NdFeB magnet preparation system provided by the present invention. DETAILED DESCRIPTION

[0032] 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.

[0033] An embodiment of the present invention discloses a high-coercivity NdFeB magnet preparation system, comprising a transition chamber, a first vacuum coating chamber, a magnet flipping chamber, a second vacuum coating chamber, a vacuum diffusion chamber and a rapid cooling chamber connected in sequence; all chambers are provided with automatic conveying rollers, adjacent chambers are connected by vacuum pipes, and gate valves are provided on the vacuum pipes connecting the transition chamber and the first vacuum coating chamber, the second vacuum coating chamber and the vacuum diffusion chamber, and the vacuum diffusion chamber and the rapid cooling chamber; all chambers are provided with vacuum pumping units and aeration valves; the transition chamber and the rapid cooling chamber are also provided with air release valves.

[0034] Furthermore, the NdFeB magnets to be processed are placed on a workpiece tray, which moves on automatic conveying rollers. The automatic conveying rollers of two adjacent bins are brought close together, and the workpiece tray can be transferred from one bin to another.

[0035] Furthermore, a flap valve is provided at one end of the transition chamber away from the first vacuum coating chamber, and the NdFeB magnet to be processed is placed by opening the flap valve.

[0036] Furthermore, the first vacuum coating chamber and the second vacuum coating chamber are provided with magnetron sputtering targets above the automatic conveying roller.

[0037] Furthermore, a magnet flipping mechanism is provided in the magnet flipping bin, and an electromagnetic suction cup can be used as the magnet flipping mechanism to grab the NdFeB magnet to be processed and flip it over; or a double workpiece disk interlocking method of one empty disk and one full disk can be used to flip the NdFeB magnet.

[0038] Furthermore, the vacuum diffusion chamber is provided with an electrically connected temperature controller and an electrically heated molybdenum belt above the automatic conveying roller, and a heat insulation screen is provided on the inner wall of the chamber.

[0039] Furthermore, a flap valve is provided at one end of the vacuum diffusion chamber of the rapid cooling chamber principle, and the prepared high coercive force NdFeB magnet is taken out by opening the flap valve.

[0040] Furthermore, the aeration valves of the transition chamber, the first vacuum coating chamber, the magnet turning chamber, the second vacuum coating chamber and the vacuum diffusion chamber are connected to the argon source, and the aeration valve of the rapid cooling chamber is connected to the liquid nitrogen source.

[0041] Furthermore, the aeration valve is connected to a mass flow meter for monitoring the amount of argon or liquid nitrogen introduced and regulating the opening of the aeration valve.

[0042] Furthermore, the magnetron sputtering target can be sputtered and coated with heavy rare earth target, light rare earth target or other metal target, and the thin film formed on the surface of the NdFeB magnet to be processed includes heavy rare earth film, light rare earth film or other metal film.

[0043] The NdFeB magnets to be processed of the present invention complete the switching from the atmospheric environment to the vacuum environment in the transition chamber, and complete the rapid cooling and switching from the vacuum environment to the atmospheric environment in the rapid cooling chamber; a photoelectric position sensor is provided in each chamber of the system to automatically detect the occupancy of the workpiece disk in each chamber. Under the premise of no collision, multiple workpiece disks can be queued in the same working chamber, moving forward in sequence, and continuously processing the NdFeB magnets to be processed.

[0044] On the other hand, in a specific embodiment, the steps of preparing a high coercive force NdFeB magnet using a high coercive force NdFeB magnet preparation system are as follows:

[0045] S1. With flap valves 1-2, gate valves 1-3, vent valves 1-2, and aeration valves 1-4 all closed, start vacuum pumping units 1-4 and evacuate the transition chamber, first vacuum coating chamber, magnet flip chamber, second vacuum coating chamber, vacuum diffusion chamber, and rapid cooling chamber until the pressure inside the chamber is ≤2×10 -3 Pa high vacuum state;

[0046] S2. Set the temperature controller in the vacuum diffusion chamber to the heavy rare earth diffusion temperature of the NdFeB magnet, such as 880°C, and start the power supply of the electric heating molybdenum strip to increase the temperature inside the chamber to reach the set temperature and maintain a constant temperature.

[0047] S3. Open aeration valve 2 and adjust the valve opening to control the amount of gas introduced, using the flow rate monitored by the mass flowmeter connected to the valve. High-purity argon is introduced to maintain a low vacuum pressure of 0.8 Pa in the first vacuum coating chamber 1, the magnet flip chamber, and the second vacuum coating chamber 2. Start the ignition power supplies for magnetron sputtering targets 1 and 2, both at a power of 20 kW, to excite the plasma and sputter the target materials mounted on them to produce particle beams.

[0048] S4. Turn off the vacuum pumping unit 1, open the vent valve 1, and fill the transition chamber with air until the pressure inside the transition chamber reaches atmospheric pressure. Then close the vent valve 1. Then open the flap valve 1, start the automatic conveyor roller, and send the workpiece tray loaded with the NdFeB magnets to be processed into the transition chamber. Close the flap valve 1. Then turn on the vacuum pumping unit 1 and empty the transition chamber to a high vacuum state, so that the pressure inside the transition chamber returns to less than or equal to 2×10 -3 Pa; then open the aeration valve 1, and adjust the opening of the aeration valve to control the amount of flow according to the flow monitored by the mass flow meter connected to it, and add high-purity argon gas into the transition chamber to maintain the pressure in the transition chamber at 0.8Pa;

[0049] S5. Open the gate valve 1, start the automatic transfer roller, transfer the workpiece tray in the transition chamber to completely enter the first vacuum coating chamber 1, and close the gate valve 1;

[0050] S6. The workpiece disk entering the first vacuum coating chamber 1 moves forward at a certain speed under the automatic conveyor roller drive, and a coating of a certain thickness (eg, 10 microns) is deposited on the surface of the NdFeB magnet to be processed when the particle beam region sputtered by the magnetron sputtering target 1 is passed;

[0051] S7. The workpiece disk continues to move forward and enters the magnet flip bin; the magnet flip mechanism in the magnet flip bin is activated, grabs the NdFeB magnet to be processed with the coating on the upper surface, flips it so that the bottom surface of the magnet faces upward, and then puts the magnet back into the workpiece disk;

[0052] S8. The workpiece disk continues to move forward and enters the second vacuum coating chamber 2. When the particle beam region sputtered by the magnetron sputtering target 2 is passed, a coating of a certain thickness (eg, 10 microns) is also deposited on the bottom surface of the NdFeB magnet to be processed;

[0053] S9. Open the aeration valve 3 and adjust the aeration valve opening to control the flow rate according to the mass flow meter connected to it. Fill the vacuum diffusion chamber with high-purity argon gas to maintain the pressure in the vacuum diffusion chamber at 0.8 Pa.

[0054] S10. Open the gate valve 2, and the automatic conveyor roller will be loaded with the workpiece disk of the NdFeB magnet to be processed with the coating on both sides to be transferred into the vacuum diffusion chamber, close the gate valve 2; then close the aeration valve 3, so that the vacuum diffusion chamber returns to a high vacuum state;

[0055] S11. The workpiece tray entering the vacuum diffusion chamber continues to move forward at a constant speed driven by the automatic conveyor roller. The temperature of the coated NdFeB magnets to be treated in the workpiece tray gradually rises under the radiation of the high-temperature molybdenum heating belt until it finally reaches the diffusion temperature (the set temperature value). It then enters a heat preservation state. Under the action of thermal activation energy, the atoms in the coating diffuse into the magnet along the grain boundaries of the main phase grains of the NdFeB magnet. When the workpiece tray moves to the end of the constant temperature zone, that is, when the heat preservation period ends, the NdFeB magnet completes the rare earth grain boundary diffusion treatment.

[0056] S12. Open the gate valve 3, and the automatic conveyor roller transfers the workpiece disc that has completed the diffusion treatment in the vacuum diffusion chamber into the rapid cooling chamber. Close the gate valve 3; then open the nitrogen aeration 4 and fill the rapid cooling chamber with a low-temperature gas such as liquid nitrogen, so that the workpiece disc and the NdFeB magnet are quickly cooled to near room temperature. Close the aeration valve 4;

[0057] S13. Turn off the vacuum pumping unit 4, open the vent valve 2, and fill air into the rapid cooling chamber until the air pressure in the rapid cooling chamber reaches atmospheric pressure, then close the vent valve 2; then open the flap valve 2, and the automatic conveyor roller returns the workpiece disk to the atmospheric environment, and close the flap valve 2; then turn on the vacuum pumping unit 4 to empty the rapid cooling chamber to a high vacuum state.

[0058] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0059] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a high coercive force neodymium iron boron magnet, characterized in that: The preparation system includes a transition chamber, a first vacuum coating chamber, a magnet turning chamber, a second vacuum coating chamber, a vacuum diffusion chamber, and a rapid cooling chamber connected in sequence; all chambers are provided with automatic conveying rollers, adjacent chambers are connected by vacuum pipes, and gate valves are provided on the vacuum pipes connecting the transition chamber and the first vacuum coating chamber, the second vacuum coating chamber and the vacuum diffusion chamber, and the vacuum diffusion chamber and the rapid cooling chamber; all chambers are provided with vacuum pumping units and aeration valves; the transition chamber and the rapid cooling chamber are also provided with air release valves; the preparation system includes the following steps: Step 1: Close all valves, start the vacuum pumping unit, and evacuate the transition chamber, the first vacuum coating chamber, the magnet turning chamber, the second vacuum coating chamber, the vacuum diffusion chamber, and the rapid cooling chamber to a high vacuum state; Step 2: Heat the vacuum diffusion chamber to the preparation temperature; Step 3: Open the gas injection valve to fill high-purity argon gas into the first vacuum coating chamber, the magnet turning chamber, and the second vacuum coating chamber, so that the first vacuum coating chamber, the magnet turning chamber, and the second vacuum coating chamber are maintained in a low vacuum state; start the sputtering particle beam flow in the first vacuum coating chamber and the second vacuum coating chamber; Step 4: Turn off the vacuum pumping unit of the transition chamber and open the air release valve of the transition chamber until the air pressure in the transition chamber reaches atmospheric pressure and then close the air release valve. Place the NdFeB magnets to be processed into the transition chamber and then turn on the vacuum pumping unit to restore the air pressure in the transition chamber to a high vacuum state. Open the aeration valve of the transition chamber and introduce high-purity argon gas to maintain the air pressure in the transition chamber at a low vacuum state. Step 5: Open the gate valve between the transition chamber and the first vacuum coating chamber, transfer the NdFeB magnets to be processed to the first vacuum coating chamber via the automatic conveyor roller, and close the gate valve; Step 6: The first vacuum coating chamber sputters a layer of coating on the upper surface of the NdFeB magnet to be processed, and the NdFeB magnet to be processed is transferred to the magnet turning chamber by an automatic conveyor roller. The magnet turning chamber turns the NdFeB magnet to be processed over and then transfers it to the second vacuum coating chamber by an automatic conveyor roller. The second vacuum coating chamber sputters a layer of coating on the lower surface of the NdFeB magnet to be processed; Step 7: Open the aeration valve of the vacuum diffusion chamber, introduce high-purity argon gas, maintain the vacuum diffusion chamber in a low vacuum state, open the gate valve between the second vacuum coating chamber and the vacuum diffusion chamber, transfer the NdFeB magnets to be processed to the vacuum diffusion chamber via the automatic conveyor roller, and close the gate valve; close the aeration valve of the vacuum diffusion chamber, open the vacuum pumping unit of the vacuum diffusion chamber, restore the vacuum diffusion chamber to a high vacuum state, heat the NdFeB magnets to be processed, and after heating is completed, open the gate valve between the vacuum diffusion chamber and the rapid cooling chamber, transfer the NdFeB magnets to be processed to the rapid cooling chamber via the automatic conveyor roller, and close the gate valve; Step 8: Open the aeration valve of the rapid cooling chamber and introduce low-temperature gas. After the NdFeB magnets to be processed are cooled to room temperature, close the vacuum pumping unit of the rapid cooling chamber and open the air release valve. After taking out the prepared high coercive force NdFeB magnets, close the air release valve of the rapid cooling chamber and open the vacuum pumping unit to restore the rapid cooling chamber to a high vacuum state.

2. The method for preparing a high coercive force NdFeB magnet according to claim 1, wherein: The NdFeB magnets to be processed are placed on a workpiece plate, which moves on automatic conveyor rollers.

3. The method for preparing a high coercive force NdFeB magnet according to claim 1, wherein: A flap valve is provided at one end of the transition chamber away from the first vacuum coating chamber, and the NdFeB magnet to be processed is placed by opening the flap valve.

4. The method for preparing a high coercive force NdFeB magnet according to claim 1, wherein: The first vacuum coating chamber and the second vacuum coating chamber are provided with magnetron sputtering targets above the automatic conveying roller.

5. The method for preparing a high coercive force NdFeB magnet according to claim 1, wherein: A magnet turning mechanism is arranged in the magnet turning bin.

6. The method for preparing a high coercive force NdFeB magnet according to claim 1, wherein: The vacuum diffusion chamber is provided with an electrically connected temperature controller and an electrically heated molybdenum belt above the automatic conveying roller, and a heat insulation screen is provided on the inner wall of the chamber.

7. The method for preparing a high coercive force NdFeB magnet according to claim 1, wherein: Principle of Rapid Cooling Chamber: A flap valve is provided at one end of the vacuum diffusion chamber, and the prepared high coercive force NdFeB magnet is taken out by opening the flap valve.

8. The method for preparing a high coercive force NdFeB magnet according to claim 1, wherein: The aeration valves of the transition chamber, the first vacuum coating chamber, the magnet turning chamber, the second vacuum coating chamber and the vacuum diffusion chamber are connected to the argon source, and the aeration valve of the rapid cooling chamber is connected to the liquid nitrogen source.

9. The method for preparing a high coercive force NdFeB magnet according to claim 1, wherein: The aeration valve is connected to a mass flow meter.

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