Vacuum heat treatment system and method for sintered neodymium-iron-boron magnet

Abstract

The invention discloses a sintered neodymium-iron-boron magnet vacuum heat treatment system and method, and belongs to the technical field of sintered neodymium-iron-boron magnet vacuum heat treatment. A plurality of heating units are arranged in an insulating layer of the furnace body; the placing mechanism comprises a plurality of cross rods used for placing the neodymium-iron-boron magnet, a main shaft, two spiral guide rails, a shielding curtain and a clamping assembly, turbines are fixedly installed at the two ends of the main shaft, and the flow guide directions of the two turbines are the same; the two spiral guide rails are fixedly installed at the two ends of the transverse rod on the outermost layer in the circumferential direction correspondingly, and the two clamping assemblies used for clamping the screen are installed on the two spiral guide rails so that the screen can be folded or encircled in the circumferential direction. The placement mechanism is mounted in the furnace body through the sliding mechanism; a refrigeration unit is fixedly installed on the base, and a flow guiding component is further arranged outside the furnace body and used for guiding flow during cooling. The problems that heating or cooling is not uniform, the heat treatment efficiency is low, the consistency is poor, and the quality of the sintered neodymium-iron-boron magnets is affected in batch sintering of the neodymium-iron-boron magnets are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of NdFeB magnet sintering equipment, in particular to a vacuum heat treatment system and method for sintering NdFeB magnets. Background Art

[0002] Sintered NdFeB magnets are high-performance permanent magnet materials widely used in new energy, electronic equipment, aerospace, and other fields due to their excellent magnetic properties. Existing sintered NdFeB magnets are mostly vacuum heat-treated in vacuum sintering furnaces. For example, the utility model patent with announcement number CN217953109U discloses a vacuum sintering device for high-coercivity NdFeB magnets, and the utility model patent with announcement number CN221005894U discloses a vacuum sintering device with uniform heating. In these patents, a closed furnace is used to sinter NdFeB magnets. The NdFeB magnets to be treated are placed in a vacuum sintering furnace. Heating elements are usually embedded in the inner wall of the furnace and distributed around the vacuum-treated NdFeB magnets. Circumferential heat radiation is used for heating. Even with the rotation of the furnace, it is still easy to cause uneven temperatures in different areas within the NdFeB magnet placement area. After high-temperature treatment, NdFeB magnets need to be cooled. This is typically done by direct air cooling with nozzles perpendicular to the work surface. However, due to the high concentration of cooling gas, surface cooling uniformity is poor, resulting in low cooling efficiency. Large NdFeB magnets are also prone to cracking, impacting the quality of the sintered NdFeB magnets. In recent years, with the optimization of processes for high-performance sintered NdFeB magnets, two or three stepped heating / holding / cooling cycles are sometimes required. Improving the heat treatment efficiency of non-zoned vacuum sintering furnaces (with heating and cooling zones) has been a technical challenge in this field. Summary of the Invention

[0003] The purpose of the present invention is to provide a vacuum heat treatment system and method for sintered NdFeB magnets to solve the problems raised in the above background technology, such as the inability to uniformly heat or cool batch sintered NdFeB magnets, low heat treatment efficiency, poor consistency, and affecting the quality of sintered NdFeB magnets.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solution: a vacuum heat treatment system for sintered NdFeB magnets, comprising: a furnace body with a plurality of heating units built into a thermal insulation layer, a base, and a placement mechanism, wherein the furnace body is horizontally fixedly mounted on the base, the placement mechanism is disposed within the furnace body, and a vacuum unit for vacuuming the inner cavity of the furnace body is disposed on the base; The placement mechanism includes multiple crossbars for placing NdFeB magnets, a main shaft, two spiral guide rails, a screen, and a clamping assembly. The multiple crossbars are arranged horizontally, and brackets are provided at both ends. The two ends of the main shaft are fixedly installed in the two brackets respectively; turbines are fixedly installed at both ends of the main shaft, and the two turbines have the same flow direction. The two spiral guide rails are fixedly mounted at both ends of the outermost crossbar along the circumferential direction, and two sets of clamping assemblies for clamping the screen are mounted on the two spiral guide rails to achieve the circumferential folding or closing of the screen; the placement mechanism is mounted in the furnace body via a sliding mechanism; A transmission component is fixedly installed at the rear end of the furnace body, the tail end of the main shaft is connected to the transmission component, a driving component is fixedly installed at the rear end of the base for driving the transmission component to operate, a refrigeration unit is fixedly installed at the front end of the base, the refrigeration unit is connected to the interior of the furnace body through a conduit, and a solenoid valve for switching on and off is fixedly installed on the conduit; A flow guiding component is also provided outside the furnace body for guiding flow during cooling.

[0005] Preferably, the clamping assembly includes two groups of moving devices, which are slidably embedded in the spiral guide rail. The screen is fixed by a horizontally arranged clamping plate, and both ends are fixedly connected to the two moving devices.

[0006] Preferably, the sliding mechanism includes a slide, a guide rail and a pushing component. The slide is sleeved on the outside of the placement mechanism, and the two ends of the main shaft are respectively rotatably installed in the slide. The guide rails are symmetrically installed on both sides of the slide. Two guide grooves are symmetrically opened on the inner wall of the furnace body. The slide is slidably embedded in the furnace body through the two guide grooves. The guide rails are in sliding contact with the guide grooves, and the pushing component is used to drive the slide to move.

[0007] Preferably, the transmission component includes a shell, a sleeve and a transmission shaft. The shell is fixedly installed at the rear end of the furnace body, the sleeve is rotatably sleeved in the shell, a keyway is provided at the tail end of the main shaft, and the keyway is engaged with the sleeve. The transmission shaft is horizontally rotatably sleeved in the shell, and the front end is fixedly connected to the rear end of the sleeve. A sealing sleeve is fixedly sleeved in the middle of the rear end of the furnace body, and the tail end of the main shaft passes through the sealing sleeve.

[0008] Preferably, the driving component includes a motor, two pulleys and a transmission belt. The motor is fixedly mounted on the upper side of the rear end of the base. The two pulleys are respectively fixedly mounted on the output shaft of the motor and the end of the transmission shaft. The transmission belt is rollingly embedded in the two pulleys.

[0009] Preferably, a cover is hingedly connected to the front end of the furnace body, and a lock is fixedly installed on one side of the furnace body.

[0010] Preferably, the guide component includes multiple clamping rings and multiple gear rings, and the multiple clamping rings are rotatably sleeved on the outside of the furnace body and sealed. The multiple gear rings are fixedly sleeved on the multiple clamping rings, and the multiple clamping rings are each horizontally provided with a first guide hole passing through. The tail end of the furnace body is provided with multiple second guide holes, the front side of the furnace body is provided with multiple third guide holes, and the cover is provided with multiple fourth guide holes. The multiple third guide holes are respectively connected to the multiple fourth guide holes. The multiple third guide holes and the multiple second guide holes are all bent, and the ends bent toward the central axis are all connected to the inside of the furnace body.

[0011] Preferably, a horizontal shaft is installed in the middle of the base for horizontal rotation, and the tail end of the horizontal shaft is fixedly connected to the output shaft of the motor through a coupling. A plurality of second gears are fixedly installed on the horizontal shaft, and the plurality of second gears are respectively engaged with a plurality of gear rings, and the gear ratios of the plurality of groups of mutually engaged gear rings and second gears are different.

[0012] A vacuum heat treatment method for sintered NdFeB magnets, characterized in that it specifically comprises the following steps: a. Place the NdFeB magnet to be sintered into the placement mechanism and surround the placement mechanism with a screen along its circumference; b. Slide the placement mechanism into the furnace body, and then evacuate the furnace body to a vacuum; c. Control the heating layer in the sintering furnace to heat up to the first temperature. At the same time, the transmission component drives the main shaft of the placement mechanism to rotate, and the turbines at both ends rotate synchronously to quickly achieve uniform heating of the workpiece placement space enclosed by the curtain; d. During the cooling process, the solenoid valve is opened, and the refrigeration unit is connected to the inside of the furnace through the conduit, and cooling gas is filled into the sintering furnace. At the same time, the main shaft rotates, driving the two turbines to rotate, which has a guiding effect on the cooling gas, making the cooling gas entering the furnace body more evenly mixed, and quickly cooling the product to the second temperature.

[0013] The beneficial effects of the present invention are as follows: The present invention uses a placement mechanism to position the NdFeB magnets to be vacuum heat-treated within the furnace. During vacuum heat treatment, the placement mechanism's circumferential screen and co-rotating turbines at both ends synergistically redirect the heat radiation from the furnace, rapidly achieving a uniform temperature within the furnace and improving sintering efficiency. The workpiece also rotates with the placement mechanism, ensuring more uniform contact with the hot air flow within the furnace. Centrifugal force also forces the hot air flow to move from the axis outward, making it easier to penetrate the workpiece, ensuring full contact and improving sintering quality.

[0014] During the rotational cooling process, the cooling gas cools the furnace body. At the same time, the cooling gas moves along the axial direction with the cooperation of the two turbines and the guide components and is randomly and evenly mixed. The cooling gas flows in multiple directions, which not only achieves better cooling efficiency, but also better cooling uniformity. It can effectively avoid the cracking of NdFeB magnet products caused by the strong concentration of cooling gas and improve the consistency of sintered NdFeB magnets. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the three-dimensional structure of a vacuum heat treatment system and method for sintered NdFeB magnets proposed by the present invention; Figure 2 This is a schematic diagram of the internal structure of a vacuum heat treatment system and method for sintered NdFeB magnets proposed in the present invention; Figure 3 A schematic side view of a partial cross-sectional structure of a vacuum heat treatment system and method for sintered NdFeB magnets proposed by the present invention; Figure 4 This is a schematic diagram of the three-dimensional structure of the placement mechanism in a vacuum heat treatment system and method for sintered NdFeB magnets proposed by the present invention; Figure 5 for Figure 2 A magnified view of the structure in Figure 2.

[0016] In the figure: 1. furnace body; 2. base; 3. spiral guide rail; 4. cross bar; 5. main shaft; 6. support frame; 7. refrigeration unit; 8. solenoid valve; 9. splint; 10. cover; 11. lock; 12. moving device; 13. curtain; 14. slide; 15. guide rail; 16. servo motor; 17. first gear; 18. rack; 19. turbine; 20. housing; 21. sleeve; 22. transmission shaft; 23. sealing sleeve; 24. motor; 25. pulley; 26. transmission belt; 27. retaining ring; 28. first guide hole; 29. ​​second guide hole; 30. third guide hole; 31. fourth guide hole; 32. gear ring; 33. cross shaft; 34. coupling; 35. second gear. DETAILED DESCRIPTION

[0017] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, what is described is only a part of the embodiments of the present invention, not all of them. 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.

[0018] See Figure 1-5A vacuum heat treatment system for sintered NdFeB magnets comprises: a furnace body 1 with a plurality of heating units built into a heat-insulating layer, a base 2, and a placement mechanism. The furnace body 1 is horizontally fixedly mounted on the base 2, the placement mechanism is arranged in the furnace body 1, and a vacuum unit for vacuuming the inner cavity of the furnace body 1 is arranged on the base 2; The placement mechanism includes multiple crossbars 4 for accommodating the NdFeB magnets, a main shaft 5, two spiral guide rails 3, a screen 13, and a clamping assembly. The crossbars 4 are arranged horizontally, with brackets 6 at each end. The two ends of the main shaft 5 are fixedly mounted within the brackets 6. Turbines 19 are fixedly mounted at each end of the main shaft 5, directing fluid in the same direction. Two spiral guide rails 3 are circumferentially fixed to the ends of the outermost crossbars 4. Two sets of clamping assemblies for clamping the screen are mounted on the two spiral guide rails 3, allowing the screen to be retracted or closed circumferentially. The placement mechanism is installed in the furnace body 1 through a sliding mechanism; A transmission component is fixedly installed at the rear end of the furnace body 1, and the tail end of the main shaft 5 is connected to the transmission component. A driving component is fixedly installed at the rear end of the base 2 for driving the transmission component to operate. A refrigeration unit 7 is fixedly installed on the base 2. The refrigeration unit 7 is connected to the interior of the furnace body 1 through a conduit, and a solenoid valve 8 for on and off is fixedly installed on the conduit; A cover 10 is hinged at the front end of the furnace body 1, and a lock 11 is fixedly installed on one side of the furnace body 1 and the cover 10; A flow guiding component is also provided outside the furnace body 1 for guiding flow during cooling.

[0019] Each electrical device is powered by an external power supply, and the entire device is controlled by a control terminal. Since the control terminal is a commonly used device and belongs to existing mature technology, its electrical connection relationship and specific circuit structure will not be described in detail here.

[0020] The clamping assembly includes two sets of moving devices 12, which are slidably embedded in the spiral guide rail 3. The screen 13 is secured by horizontal clamping plates 9, with both ends fixedly connected to the two moving devices 12. During loading or unloading, the two moving devices 12 operate (either electrically or manually) to circumferentially retract or close the screen 13.

[0021] The sliding mechanism includes a slide 14, a guide rail 15 and a pushing component. The slide 14 is sleeved on the outside of the placement mechanism, and the two ends of the main shaft 5 are respectively rotatably installed in the slide 14. The guide rails 15 are symmetrically installed on both sides of the slide 14. Two guide grooves are symmetrically opened on the inner wall of the furnace body 1. The slide 14 is slidably embedded in the furnace body 1 through the two guide grooves. The guide rails 15 are in sliding contact with the guide grooves, and the pushing component is used to drive the slide 14 to move.

[0022] The pushing assembly includes a servo motor 16, a first gear 17, and a rack 18. The servo motor 16 is fixedly mounted on the top front side of the furnace body 1, and the rack 18 is horizontally fixedly mounted on the top of the carriage 14. The first gear 17 is fixedly mounted on the output shaft of the servo motor 16 and meshes with the rack 18. When loading or unloading, the servo motor 16 is started, and the rack 18 is driven by the first gear 17 to move. The rack 18 then drives the carriage 14 to move, causing the placement mechanism to move out of the furnace body 1.

[0023] The transmission components include a shell 20, a sleeve 21 and a transmission shaft 22. The shell 20 is fixedly installed at the rear end of the furnace body 1. The sleeve 21 is rotatably sleeved in the shell 20. A keyway is provided at the tail end of the main shaft 5, which is engaged with the sleeve 21 through the keyway. The transmission shaft 22 is horizontally rotatably sleeved in the shell 20, and the front end is fixedly connected to the rear end of the sleeve 21. A sealing sleeve 23 is fixedly sleeved in the middle of the rear end of the furnace body 1, and the tail end of the main shaft 5 passes through the sealing sleeve 23.

[0024] The driving components include a motor 24, two pulleys 25 and a transmission belt 26. The motor 24 is fixedly mounted on the upper side of the rear end of the base 2. The two pulleys 25 are respectively fixedly mounted on the output shaft of the motor 24 and the end of the transmission shaft 22. The transmission belt 26 is rollingly embedded in the two pulleys 25.

[0025] When using this equipment to perform vacuum heat treatment on NdFeB, the screen is first fixed using two sets of clamping assemblies. The placement mechanism is then moved into the furnace body 1. The cover 10 is then closed, sealing the furnace body 1. At the same time, the furnace body is evacuated. The heating unit is then started. After preheating, the motor 24 is started. The motor 24 drives the transmission components through two pulleys 25 and a transmission belt 26. The main shaft 5 is driven to rotate through the transmission shaft 22 and the sleeve 21. The main shaft 5 drives the crossbar 4 through the two supports 6, thereby rotating the workpiece. The circumferential screen of the placement mechanism and the turbines rotating in the same direction at both ends work together to change the direction of heat radiation from the furnace body, allowing the interior of the furnace body to quickly reach a uniform temperature, effectively improving sintering efficiency.

[0026] The guide component includes multiple snap rings 27 and multiple gear rings 32. The multiple snap rings 27 are rotatably sleeved on the outside of the furnace body 1 and are sealed. The multiple gear rings 32 are respectively fixedly sleeved on the multiple snap rings 27. Multiple first guide holes 28 are axially penetrated in the multiple snap rings 27. Multiple second guide holes 29 are opened at the tail end of the furnace body 1. Multiple third guide holes 30 are opened on the front side of the furnace body 1. Multiple fourth guide holes 31 are opened in the cover 10. The multiple third guide holes 30 are respectively connected to the multiple fourth guide holes 31. The multiple third guide holes 30 and the multiple second guide holes 29 are all bent, and the ends bent toward the central axis are connected to the inside of the furnace body 1. At any time, at least one group of first guide holes 28, second guide holes 29, third guide holes 30 and fourth guide holes 31 are in a conductive state.

[0027] A horizontal shaft 33 is installed in the middle of the base 2 for horizontal rotation. The tail end of the horizontal shaft 33 is fixedly connected to the output shaft of the motor 24 through a coupling 34. A plurality of second gears 35 are fixedly installed on the horizontal shaft 33. The plurality of second gears 35 are respectively engaged with a plurality of ring gears 32. The gear ratios of the plurality of groups of mutually engaged ring gears 32 and the second gears 35 are all different.

[0028] During the cooling process, the electromagnetic valve 8 is opened, and the refrigeration unit 7 is connected to the inside of the furnace body 1 through the conduit. At the same time, the main shaft 5 rotates, driving the two turbines 19 to rotate. The two turbines 19 guide the cooling gas, ensuring a more even mixing of the cooling gas entering the furnace. As the motor 24 rotates, it drives the horizontal shaft 33 through the coupling 34. The horizontal shaft 33, through the multiple second gears 35 thereon, drives the multiple ring gears 32 to rotate. The ring gears 32 then drive the connected snap ring 27 to rotate. Because the gear ratios of the multiple meshing ring gears 32 and the second gears 35 vary, the transmission ratios vary, and the speed of the snap ring 27 varies, with some rotating faster and some slower.

[0029] Under the action of the turbine 19, the cooling gas flows to the end of the cover 10, enters the multiple third guide holes 30 through the multiple fourth guide holes 31, and then enters the first guide holes 28 in the retaining ring 27 through the third guide holes 30. Since the multiple retaining rings 27 rotate at different speeds, the multiple first guide holes 28 are intermittently connected, and the cooling gas flowing in from different fourth guide holes 31 is randomly mixed in the multiple first guide holes 28, and finally flows into the furnace body 1 through the second guide holes 29.

[0030] During the rotational cooling process, the flow of cooling gas in the third guide hole 30 and the first guide hole 28 in the retaining ring 27 realizes the cooling of the furnace body 1. At the same time, the cooling gas moves along the axial direction with the cooperation of the two turbines 19 and the guide components, and is randomly and evenly mixed. The cooling gas flows in multiple directions, which not only achieves better cooling efficiency, but also better cooling uniformity, and can effectively avoid the cracking of NdFeB magnet products caused by the strong concentration of cooling gas, thereby improving the consistency of sintered NdFeB magnets.

[0031] A vacuum heat treatment method for sintered NdFeB magnets specifically comprises the following steps: a. Place the NdFeB magnet to be sintered into the placement mechanism and surround the placement mechanism with a screen along its circumference; b. Slide the placement mechanism into the furnace body, and then evacuate the furnace body to a vacuum; c. Control the heating layer in the sintering furnace to heat up to the first temperature. At the same time, the transmission component drives the main shaft of the placement mechanism to rotate, and the turbines at both ends rotate synchronously to quickly achieve uniform heating of the workpiece placement space enclosed by the curtain; d. During the cooling process, the solenoid valve is opened, and the refrigeration unit is connected to the inside of the furnace through the conduit, and cooling gas is filled into the sintering furnace. At the same time, the main shaft rotates, driving the two turbines to rotate, which has a guiding effect on the cooling gas, making the cooling gas entering the furnace body more evenly mixed, and quickly cooling the product to the second temperature.

[0032] The above vacuum heat treatment process may include multiple aging treatments at different temperatures, such as the first temperature is 800°C-900°C, the holding time is 3 hours; the second temperature is 500°C-600°C, the second aging treatment time is 4 hours; the third temperature is 400°C-500°C, the third aging treatment time is 5 hours, and all operations can be carried out according to the above steps.

[0033] 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 vacuum heat treatment system for sintered NdFeB magnets, comprising: A furnace body (1) having a plurality of heating units built into the thermal insulation layer, a base (2) and a placement mechanism, the furnace body (1) being fixedly mounted horizontally on the base (2), the placement mechanism being arranged in the furnace body (1), and a vacuum unit for vacuuming the inner cavity of the furnace body (1) being arranged on the base (2); The invention is characterized in that: the placement mechanism comprises a plurality of cross bars (4) for placing the NdFeB magnets, a main shaft (5), two spiral guide rails (3), a screen (13) and a clamping assembly, the plurality of cross bars (4) are all arranged horizontally, and support frames (6) are provided at both ends, and the two ends of the main shaft (5) are respectively fixedly installed in the two support frames (6); turbines (19) are fixedly installed at both ends of the main shaft (5), and the two turbines (19) have the same flow direction; The two spiral guide rails (3) are respectively fixedly mounted at both ends of the outermost crossbar (4) along the circumferential direction, and two sets of clamping assemblies for clamping the screen are mounted on the two spiral guide rails (3) to achieve the circumferential folding or closing of the screen; the placement mechanism is mounted in the furnace body (1) via a sliding mechanism; A transmission component is fixedly mounted on the rear end of the furnace body (1), the tail end of the main shaft (5) is connected to the transmission component, and a driving component is fixedly mounted on the rear end of the base (2) for driving the transmission component to operate; a refrigeration unit (7) is fixedly mounted on the base (2), and the refrigeration unit (7) is connected to the interior of the furnace body (1) through a conduit, and a solenoid valve (8) for switching on and off is fixedly mounted on the conduit; A flow guiding component is also provided on the outside of the furnace body (1) for guiding flow during cooling.

2. A vacuum heat treatment system for sintered NdFeB magnets according to claim 1, characterized in that: The clamping assembly comprises two groups of moving devices (12), the two groups of moving devices (12) are slidably embedded in the spiral guide rail (3), and the screen (13) is fixed by a horizontally arranged clamping plate, and both ends are fixedly connected to the two moving devices (12).

3. The vacuum heat treatment system for sintered NdFeB magnets according to claim 1, characterized in that: The sliding mechanism includes a slide (14), a guide rail (15) and a pushing component. The slide (14) is sleeved on the outside of the placement mechanism, and the two ends of the main shaft (5) are respectively rotatably mounted in the slide (14). The guide rail (15) is symmetrically mounted on both sides of the slide (14). Two guide grooves are symmetrically opened on the inner wall of the furnace body (1). The slide (14) is slidably embedded in the furnace body (1) through the two guide grooves. The guide rail (15) is in sliding contact with the guide groove. The pushing component is used to drive the slide (14) to move.

4. A vacuum heat treatment system for sintered NdFeB magnets according to claim 1, characterized in that: The transmission component comprises a housing (20), a sleeve (21) and a transmission shaft (22); the housing (20) is fixedly mounted on the rear end of the furnace body (1); the sleeve (21) is rotatably sleeved in the housing (20); a keyway is provided at the rear end of the main shaft (5) and is engaged with the sleeve (21) through the keyway; the transmission shaft (22) is horizontally rotatably sleeved in the housing (20), and the front end is fixedly connected to the rear end of the sleeve (21); a sealing sleeve (23) is fixedly sleeved in the middle of the rear end of the furnace body (1); and the rear end of the main shaft (5) passes through the sealing sleeve (23).

5. A vacuum heat treatment system for sintered NdFeB magnets according to claim 4, characterized in that: The driving component comprises a motor (24), two pulleys (25) and a transmission belt (26); the motor (24) is fixedly mounted on the upper side of the rear end of the base (2); the two pulleys (25) are respectively fixedly mounted on the output shaft of the motor (24) and the end of the transmission shaft (22); and the transmission belt (26) is rollingly embedded in the two pulleys (25).

6. A vacuum heat treatment system for sintered NdFeB magnets according to claim 1, characterized in that: A cover (10) is hingedly connected to the front end of the furnace body (1), and a lock buckle (11) is fixedly installed on one side of the furnace body (1) and the cover (10).

7. A vacuum heat treatment system for sintered NdFeB magnets according to claim 5, characterized in that: The flow guide component includes a plurality of clamping rings (27) and a plurality of gear rings (32), the plurality of clamping rings (27) are rotatably sleeved on the outside of the furnace body (1) and are sealed, the plurality of gear rings (32) are fixedly sleeved on the plurality of clamping rings 27, and the plurality of clamping rings (27) are horizontally provided with a first flow guide hole (28) passing through, the tail end of the furnace body (1) is provided with a plurality of second flow guide holes (29), the front side of the furnace body (1) is provided with a plurality of third flow guide holes (30), the cover (10) is provided with a plurality of fourth flow guide holes (31), the plurality of third flow guide holes (30) are respectively connected to the plurality of fourth flow guide holes (31), the plurality of third flow guide holes (30) and the plurality of second flow guide holes (29) are all bent, and the ends bent toward the central axis are connected to the inside of the furnace body (1).

8. A vacuum heat treatment system and method for sintered NdFeB magnets according to claim 7, characterized in that: A horizontal shaft (33) is mounted in the middle of the base (2) for horizontal rotation. The tail end of the horizontal shaft (33) is fixedly connected to the output shaft of the motor (24) via a coupling (34). A plurality of second gears (35) are fixedly mounted on the horizontal shaft (33). The plurality of second gears (35) are respectively meshed with a plurality of ring gears (32). The gear ratios of the plurality of groups of meshing ring gears (32) and second gears (35) are all different.

9. A vacuum heat treatment method for sintered NdFeB magnets, characterized by: The specific steps include: a. Place the NdFeB magnet to be sintered into the placement mechanism and surround the placement mechanism with a screen along its circumference; b. Slide the placement mechanism into the furnace body, and then evacuate the furnace body to a vacuum; c. Control the heating layer in the sintering furnace to heat up to the first temperature. At the same time, the transmission component drives the main shaft of the placement mechanism to rotate, and the turbines at both ends rotate synchronously to quickly achieve uniform heating of the workpiece placement space enclosed by the curtain; d. During the cooling process, the solenoid valve is opened, and the refrigeration unit is connected to the inside of the furnace through the conduit, and cooling gas is filled into the sintering furnace. At the same time, the main shaft rotates, driving the two turbines to rotate, which has a guiding effect on the cooling gas, making the cooling gas entering the furnace body more evenly mixed, and quickly cooling the product to the second temperature.

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