High-coercivity neodymium-iron-boron magnet preparation system and method

Abstract

The invention discloses a high-coercivity neodymium-iron-boron magnet preparation system and method, and relates to the technical field of material preparation, and the system comprises a transition bin, a first vacuum coating bin, a magnet turnover bin, a second vacuum coating bin, a vacuum diffusion bin and a rapid cooling bin which are connected in sequence; automatic conveying rollers are arranged in all the bins, every two adjacent bins are communicated through a vacuum pipeline, and gate valves are arranged on the vacuum pipelines for communicating the transition bin with the first vacuum coating bin, communicating the second vacuum coating bin with the vacuum diffusion bin and communicating the vacuum diffusion bin with the rapid cooling bin; each bin body is provided with a vacuumizing unit and an air doping valve; the transition bin and the rapid cooling bin are further provided with deflation valves. According to the method, the vacuum coating process module and the vacuum grain boundary diffusion process module are integrated, and efficient and large-scale preparation of the high-coercivity and high-performance neodymium-iron-boron magnetic material is achieved.

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 coercive force NdFeB magnet. Background Art

[0002] The heavy rare earth grain boundary diffusion technology of NdFeB magnets refers to first 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 the heavy rare earth atoms to penetrate into the magnets along the grain boundaries. 2 Fe 14 A heavy rare earth-rich shell with a higher magnetocrystalline anisotropy field is formed on the shallow surface of the B main phase grains, achieving the purpose 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 of NdFeB magnets has been around for less than 20 years, its development and large-scale application are extremely rapid. At this stage, it has basically become an essential means for the preparation of high-performance NdFeB magnets. At present, the most widely used technical route for industrial application of heavy rare earth grain boundary diffusion of NdFeB magnets is to first use magnetron sputtering coating equipment to coat the front and back of NdFeB magnets with heavy rare earth dysprosium or terbium, turn them over in the atmosphere after taking them out, and then send them to the vacuum magnetron sputtering coating equipment for a second time to coat the back of the magnetic block with heavy rare earth. After they are taken out of the furnace, they are loaded into the vacuum diffusion furnace in batches for high-temperature diffusion treatment, that is, they undergo multiple process steps such as vacuuming, heating, insulation and cooling. On the one hand, the repeated exposure of NdFeB magnets coated with heavy rare earth to the atmosphere will cause 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 causes energy waste. Therefore, it is of great economic and social significance to integrate the two processes of heavy rare earth vacuum coating and vacuum diffusion into a continuous production line.

[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 technical personnel 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, which is an overall industrialized continuous production system that uses grain boundary diffusion technology to improve 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 solution:

[0006] A high coercive force 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; all chambers are provided with automatic conveying rollers, two adjacent chambers are connected via 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.

[0007] Preferably, the NdFeB magnets to be processed are placed on a workpiece tray, and the workpiece tray moves on an automatic conveying roller. The automatic conveying rollers of two adjacent warehouses are close to each other, so that the workpiece tray can be transferred from one warehouse 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 suction cup can be selected as the magnet flipping mechanism to grab the NdFeB magnet to be processed and flip it; or a double workpiece disk interlocking method of one empty disk and one full disk can be selected 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 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.

[0013] Preferably, the gas injection 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 gas source, and the gas injection 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 preparation system, comprises the following steps:

[0018] Step 1: Close all valves, start the vacuum 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: heating the vacuum diffusion chamber to the preparation temperature;

[0020] Step 3: Open the gas injection valve to fill the first vacuum coating chamber, the magnet turning chamber and the second vacuum coating chamber with high-purity argon gas, 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 first vacuum coating chamber and the second vacuum coating chamber to sputter the heavy rare earth particle beam;

[0021] Step 4: Turn off the vacuum pumping unit of the transition chamber, and open the vent valve of the transition chamber until the air pressure in the transition chamber reaches atmospheric pressure, then close the vent valve, put 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 gas injection 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 through the automatic conveying 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 conveying roller. The magnet turning chamber turns over the NdFeB magnet to be processed and then transfers the NdFeB magnet to be processed to the second vacuum coating chamber by an automatic conveying 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 through the automatic conveying 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 the 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 through the automatic conveying roller, and close the gate valve;

[0025] Step 8: Open the gas injection valve of the rapid cooling chamber, introduce low-temperature gas, and after the NdFeB magnet to be processed is cooled to room temperature, close the vacuum unit of the rapid cooling chamber and open the venting valve; after taking out the prepared high coercive force NdFeB magnet, close the venting valve of the rapid cooling chamber and open the vacuum unit to restore the rapid cooling chamber to a high vacuum state.

[0026] It can be seen from the above technical solutions that compared with the prior art, the present invention discloses a system and method for preparing high coercive force NdFeB magnets, 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 emission 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 the 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 magnetic materials. 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0031] Figure 1 A schematic diagram of the structure of a high coercive force NdFeB magnet preparation system provided by the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0033] The embodiment of the present invention discloses a high coercive force NdFeB magnet preparation system, comprising 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; all chamber bodies are provided with automatic conveying rollers, two adjacent chamber bodies are connected through 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 chamber bodies 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, and the workpiece tray moves on an automatic conveying roller. The automatic conveying rollers of two adjacent warehouses are close to each other, and the workpiece tray can be transferred from one warehouse 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 selected as the magnet flipping mechanism to grab the NdFeB magnet to be processed and flip it; or a double workpiece tray interlocking method of one empty tray and one full tray can be selected 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 gas injection 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 gas source, and the gas injection 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 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.

[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 the switching from the vacuum environment to the atmospheric environment in the rapid cooling chamber; each chamber of the system is provided with a photoelectric position sensor which can automatically detect the occupancy of the workpiece disk in each chamber, and 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 to evacuate the transition chamber, the first vacuum coating chamber, the magnet flip chamber, the second vacuum coating chamber, the vacuum diffusion chamber, and the rapid cooling chamber until the pressure in the chamber is ≤2×10 -3 Pa high vacuum state;

[0046] S2. Set the temperature value of the temperature controller in the vacuum diffusion chamber to the diffusion temperature of the heavy rare earth of the NdFeB magnet, such as 880°C, start the power supply of the electric heating molybdenum belt, so that the temperature in the chamber rises to the set temperature value and maintains a constant temperature;

[0047] S3. Open the aeration valve 2, and adjust the opening of the aeration valve to control the amount of gas introduced according to the flow rate monitored by the mass flow meter connected thereto, and add high-purity argon gas to maintain the pressure in the first vacuum coating chamber 1, the magnet turning chamber and the second vacuum coating chamber 2 at a low vacuum state of 0.8 Pa; turn on the ignition power supply of the magnetron sputtering target 1 and the magnetron sputtering target 2, both with a power of 20KW, so that the target materials installed on the magnetron sputtering target 1 and the magnetron sputtering target 2 sputter out particle beams under plasma excitation;

[0048] S4. Close the vacuum pumping unit 1, open the vent valve 1, fill the transition chamber with air until the air pressure in the transition chamber reaches atmospheric pressure, and then close the vent valve 1; then open the flap valve 1, start the automatic conveying roller, and send the workpiece plate loaded with the NdFeB magnets to be processed into the transition chamber, and close the flap valve 1; then open the vacuum pumping unit 1, empty the transition chamber to a high vacuum state, and restore the air pressure in the transition chamber 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 gas introduced according to the flow rate 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 conveying roller, convey the workpiece disc 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 drive of the automatic conveyor roller, and deposits a coating of a certain thickness (such as 10 microns) on the surface of the NdFeB magnet to be processed when passing through the particle beam area sputtered by the magnetron sputtering target 1;

[0051] S7. The workpiece tray continues to move forward and enters the magnet flipping bin; the magnet flipping mechanism in the magnet flipping bin is started, and the NdFeB magnet to be processed with the coating on the upper surface is grabbed and flipped so that the bottom surface of the magnet faces upward, and then the magnet is put back into the workpiece tray;

[0052] S8. The workpiece disk continues to move forward and enters the second vacuum coating chamber 2. When passing through the particle beam area sputtered by the magnetron sputtering target 2, 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 opening of the aeration valve to control the amount of air entering according to the mass flow meter connected to it to monitor the flow rate, and fill the vacuum diffusion chamber with high-purity argon gas to maintain the pressure in the vacuum diffusion chamber at 0.8Pa;

[0054] S10. Open the gate valve 2, and the automatic conveyor roller conveys the workpiece disk loaded with the NdFeB magnets to be processed with the coating on both sides into the vacuum diffusion chamber, and closes the gate valve 2; then close the aeration valve 3 to restore the vacuum diffusion chamber to a high vacuum state;

[0055] S11. The workpiece disk entering the vacuum diffusion chamber continues to move forward at a certain speed under the drive of the automatic conveyor roller. The temperature of the NdFeB magnet block to be treated with the coating in the workpiece disk gradually rises under the radiation of the high-temperature molybdenum heating belt until it finally reaches the diffusion temperature (the set temperature value), and then enters the 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 disk moves to the end of the constant temperature zone, that is, when the heat preservation ends, the NdFeB magnet completes the rare earth grain boundary diffusion treatment;

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

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

[0058] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0059] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high coercivity NdFeB magnet preparation system, characterized in that: It 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 which are connected in sequence; all chambers are provided with automatic conveying rollers, and 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 air injection valves; the transition chamber and the rapid cooling chamber are also provided with air release valves.

2. A high coercivity NdFeB magnet preparation system according to claim 1, characterized in that: The NdFeB magnets to be processed are placed on a workpiece plate, which moves on automatic conveyor rollers.

3. A high coercivity NdFeB magnet preparation system according to claim 1, characterized in that: A flap valve is arranged 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. A high coercivity NdFeB magnet preparation system according to claim 1, characterized in that: The first vacuum coating chamber and the second vacuum coating chamber are provided with magnetron sputtering targets above the automatic conveying roller.

5. A high coercivity NdFeB magnet preparation system according to claim 1, characterized in that: A magnet turning mechanism is arranged in the magnet turning bin.

6. A high coercivity NdFeB magnet preparation system according to claim 1, characterized in that: 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. A high coercivity NdFeB magnet preparation system according to claim 1, characterized in that: Rapid Cooling Chamber Principle 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. A high coercivity NdFeB magnet preparation system according to claim 1, characterized in that: The gas injection 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 gas source, and the gas injection valve of the rapid cooling chamber is connected to the liquid nitrogen source.

9. A high coercivity NdFeB magnet preparation system according to claim 1, characterized in that: The aeration valve is connected to a mass flow meter.

10. A method for preparing a high coercive force NdFeB magnet, characterized in that: A high coercivity NdFeB magnet preparation system as claimed in any one of claims 1 to 9, comprising the following steps: Step 1: Close all valves, start the vacuum 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: heating the vacuum diffusion chamber to the preparation temperature; Step 3: Open the gas injection valve to fill the first vacuum coating chamber, the magnet turning chamber and the second vacuum coating chamber with high-purity argon gas, 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 beams of 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 vent valve of the transition chamber until the air pressure in the transition chamber reaches atmospheric pressure, then close the vent valve, put 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 gas injection 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 through the automatic conveying 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 conveying roller. The magnet turning chamber turns over the NdFeB magnet to be processed and then transfers the NdFeB magnet to be processed to the second vacuum coating chamber by an automatic conveying 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 through the automatic conveying 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 the 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 through the automatic conveying roller, and close the gate valve; Step 8: Open the gas injection valve of the rapid cooling chamber, introduce low-temperature gas, and after the NdFeB magnet to be processed is cooled to room temperature, close the vacuum unit of the rapid cooling chamber and open the venting valve; after taking out the prepared high coercive force NdFeB magnet, close the venting valve of the rapid cooling chamber and open the vacuum unit to restore the rapid cooling chamber to a high vacuum state.

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