Process for manufacturing sintered neodymium-iron-boron with high magnetic properties

Abstract

This invention relates to the field of magnet manufacturing technology and discloses a manufacturing process for high-magnetic-performance sintered NdFeB magnets. Step one: Melting, where raw materials are fed into a melting furnace for melting and casting. Step two: Hydrogen crushing and air jet milling, utilizing the hydrogen absorption properties of rare earth metal compounds, the NdFeB alloy is placed in a hydrogen environment. Hydrogen enters the alloy along the NdFeB-rich phase thin layer, causing it to expand and break, thus turning the thin sheet into coarse powder. An air jet mill is then used to process the coarse powder into fine powder. Step three: Forming, where the fine powder is placed in a molding die in a pressing machine. Inside the container, the product is pressed and shaped; Step 4: Sintering, the shaped product is placed in a sintering furnace for sintering at a sintering temperature of 1020-1035℃ for 3.5-5.0h, and then aged at 450-600℃ for 4-6h. It can then be taken out of the sintering furnace; Among them, the air jet mill processes the coarse powder twice. The coarse powder that has been hydrogenated is subjected to the first air jet mill to obtain 3-4μm powder; when the second air jet mill is performed, powder with an average particle size ≤2.5μm is obtained.

Description

Technical Field

[0001] This invention relates to the field of magnet manufacturing technology, specifically to a manufacturing process for high-magnetic-performance sintered NdFeB magnets. Background Technology

[0002] Neodymium iron boron (NdFeB) magnetic materials are the third generation of rare earth permanent magnet materials and also the generation with the best comprehensive performance. NdFeB is further divided into three types: sintered NdFeB, bonded NdFeB, and hot-pressed NdFeB. Among them, sintered NdFeB has excellent magnetic properties and good corrosion resistance, and is the most widely used.

[0003] The preparation of sintered NdFeB magnetic materials requires the use of a pressing machine. The pressing machine is a device that transforms fine powder into a finished product, facilitating subsequent sintering processes. The quality of the pressed product has a significant impact on the subsequent sintering process, making the pressing step crucial.

[0004] Because the material placement point remains constant when adding material to the lower mold frame, the material at the placement point is always higher than the material in other areas and is continuously impacted by the material falling directly from the top. As a result, the material density is relatively higher than that in other areas. This leads to cracks appearing at the junction of density and thickness in the product after mold closing and pressing due to the different material densities within the lower mold frame. Summary of the Invention

[0005] The purpose of this invention is to provide a manufacturing process for high-magnetic-performance sintered NdFeB magnets, thereby solving the above-mentioned technical problems.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A manufacturing process for high-magnetic-performance sintered NdFeB magnets includes:

[0008] Step 1: Melting, the raw materials are sent into the melting furnace for melting and casting;

[0009] Step 2: Hydrogen crushing and air jet milling. Utilizing the hydrogen absorption properties of rare earth metal compounds, the neodymium iron boron alloy is placed in a hydrogen environment. The hydrogen will enter the alloy along the neodymium-rich phase thin layer, causing it to expand and break, thus turning the thin sheet into coarse powder. The coarse powder is then processed into fine powder using an air jet mill.

[0010] Step 3: Shaping. The fine powder is placed in the mold of the pressing and shaping machine for pressing and shaping. Specifically, when adding fine powder to the lower mold frame, the drive motor is started and the valve at the bottom of the feeding cylinder is opened. The fine powder is automatically injected into the lower mold frame under its own weight. By expanding the feeding point area of ​​the feeding cylinder, the feeding posture of the feeding cylinder is further diversified, so that the fine powder can be evenly distributed. This prepares for the subsequent sintering process.

[0011] Step 4: Sintering. The formed product is placed in a sintering furnace for sintering at a sintering temperature of 1020-1035℃ for 3.5-5.0 hours. Then, it is aged at 450-600℃ for 4-6 hours. After being removed from the sintering furnace, the neodymium iron boron magnet is produced. The sintered neodymium iron boron magnet is then sampled and tested.

[0012] As a further aspect of the present invention: the air jet mill processes the coarse powder twice.

[0013] The coarse powder that has been hydrogenated is subjected to a first air jet milling process to obtain 3-4 μm powder.

[0014] During the second air jet milling process, a dispersant was added at a ratio of 0.03-0.05 wt% of the powder to obtain a powder with an average particle size ≤2.5 μm.

[0015] The dispersant is polyacrylic acid.

[0016] As a further aspect of the present invention: the compression molding machine includes:

[0017] A base, on which a lower mold frame is provided, and an upper mold plate is connected to the base via a hydraulic lifting column;

[0018] A pressure block is fixed to the bottom of the upper template and is correspondingly arranged with the lower template frame;

[0019] A material-laying mechanism is used to uniformly lay material onto the lower mold frame.

[0020] By using the above technical solution, the material is evenly distributed on the lower mold frame, thereby improving the quality of the product after pressing and molding.

[0021] As a further aspect of the present invention: the fabric mechanism includes:

[0022] A support frame, which is fixedly mounted on the base;

[0023] A lead screw is rotatably mounted on the side of the upright frame facing the lower mold and is connected to a drive motor fixedly mounted on the upright frame.

[0024] A sliding rod is arranged parallel to the lead screw, and the sliding rod is fixedly mounted on the upright and located on the same side as the lead screw;

[0025] A slide block, which is sleeved on the lead screw and the slide rod;

[0026] A swing arm, one end of which is fixedly provided with a rotating shaft, which is rotatably connected to the slide block, and the other end is provided with a fabric cylinder;

[0027] A rotating motor is fixedly mounted on the bottom surface of the slide block and is connected to the rotating shaft for transmission.

[0028] The above technical solution provides a specific structure for the material distribution mechanism, which achieves the purpose of uniformly distributing material to the lower mold frame.

[0029] As a further aspect of the present invention: the swing arm is provided with a swing component, which is used to change the posture of the fabric cylinder when the fabric is being laid.

[0030] By using the above technical solutions, the orientation of the fabric tube can be changed, thus expanding the selectivity of fabric selection.

[0031] As a further aspect of the present invention: the swing assembly includes:

[0032] A slide groove is formed on the side of the rocker arm away from the slide block;

[0033] A limiting sleeve, the diameter of which is larger than the groove diameter of the slide, and the limiting sleeve is rotatably connected to the fabric cylinder;

[0034] An electric push rod is fixed to the swing arm, and the telescopic end of the electric push rod is detachably and fixedly connected to the limiting sleeve.

[0035] The above technical solution provides a specific structure for an oscillating component to achieve the purpose of adjusting the fabric trajectory of the fabric cylinder.

[0036] As a further aspect of the present invention: the base is provided with a movable groove, the length of the movable groove facing the upright is greater than the length of the lower mold frame, and a linkage component is installed on the fabric cylinder, the linkage component driving the lower mold frame to move in the movable groove while being covered with fabric.

[0037] The above technical solution enables the lower mold frame to be shaken, making the material inside the lower mold frame more uniform and improving the quality of the product after pressing and molding.

[0038] As a further aspect of the present invention: the linkage component includes:

[0039] A toothed ring, which is fixed to the outer wall of the fabric cylinder;

[0040] A rack is fixedly provided at the bottom of the groove, and the rack meshes with a gear;

[0041] A protrusion is installed on the outer side of the bottom of the fabric cylinder, and the outer diameter of the protrusion is larger than the width of the lower mold frame.

[0042] The above technical solution provides a specific structure for a linkage component, enabling the linkage between the swing component and the linkage component to work together, and allowing the lower mold frame to swing while the material is being laid.

[0043] As a further embodiment of the present invention: a limiting block is provided on the outer side of the bottom of the fabric cylinder, a limiting groove is provided on the limiting block, the protrusion is slidably installed in the limiting groove, an electromagnet is installed in the limiting groove, a permanent magnet is embedded and connected on the protrusion, and the electromagnet and the permanent magnet are positioned opposite each other.

[0044] The above technical solution enables the bump position to be adjustable, thereby facilitating the switching of the bump between working and non-working states.

[0045] The beneficial effects of this invention are:

[0046] (1) This invention provides a manufacturing process for high magnetic performance sintered NdFeB magnets, including the steps of melting, hydrogen crushing, air jet milling, forming and sintering. By improving the state of fine powder injection into the lower mold frame during pressing, the purpose of multi-point uniform material distribution is achieved, reducing the situation of high in the middle and low around the edges caused by the constant material distribution points, which leads to crack defects at the density and thickness junction of the product after mold pressing, thus preparing for subsequent sintering treatment and improving the quality of NdFeB magnets.

[0047] (2) In this invention, the gear and gear ring in the linkage component cooperate to make the material cylinder rotate during the reciprocating movement of the material cylinder in the case of a straight groove. The material cylinder drives the bottom protrusion to rotate. Since the outer diameter of the protrusion is larger than the width of the lower mold frame, it will push the lower mold frame to move towards the movable groove. When the protrusion rotates to the other side, it pushes the lower mold frame back to its original position. By changing the position of the lower mold frame during the material feeding process, the lower mold frame moves back and forth while the material feeding point of the material cylinder remains unchanged. This relatively changes the material feeding point, further enhancing the uniformity of the material feeding. At the same time, during the reciprocating movement of the lower mold frame, the internal material is shaken, which reduces the gap between the materials after relative movement, further promoting the uniformity of the material feeding and improving the quality of the pressed product.

[0048] (3) When the protrusion is working, the electromagnet is energized and magnetized, thereby repelling the permanent magnet downward. The permanent magnet drives the protrusion to move downward in the limiting groove, overcoming the support spring at the bottom of the limiting groove, so that the protrusion falls from a high place into the lower mold frame. When the protrusion rotates around the working area, it pushes the lower mold frame. Once the work is completed, the electromagnet is de-energized and demagnetized, and the support spring is elastically reset, thereby pushing the protrusion back to the top position of the limiting groove. At this time, the protrusion is separated from the lower mold frame and can be pushed out of the working area of ​​the upper mold along with the cloth cylinder and the swing arm. Attached Figure Description

[0049] The invention will now be further described with reference to the accompanying drawings.

[0050] Figure 1 This is a process flow diagram of the present invention;

[0051] Figure 2 This is a front view of the compression molding machine in this invention;

[0052] Figure 3 for Figure 2 A schematic diagram of a local three-dimensional structure;

[0053] Figure 4 This is a three-dimensional structural diagram of the linkage component in this invention;

[0054] Figure 5 This is a diagram of the internal structure of the linkage component in this invention.

[0055] Figure Descriptions: 1. Base; 2. Lower mold frame; 3. Hydraulic lifting column; 4. Upper template; 5. Pressure block; 6. Fabric feeding mechanism; 61. Stand; 62. Lead screw; 63. Drive motor; 64. Slide rod; 65. Slide seat; 66. Swing arm; 67. Rotating shaft; 68. Fabric feeding cylinder; 69. Rotating motor; 7. Swing assembly; 71. Slide groove; 72. Limiting sleeve; 73. Electric push rod; 8. Movable groove; 9. Linkage assembly; 91. Gear ring; 92. Gear rack; 93. Protrusion; 94. Limiting block; 95. Limiting groove; 96. Electromagnet; 97. Permanent magnet. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Please see Figure 1-5 As shown, this invention relates to a manufacturing process for high-magnetic-performance sintered NdFeB magnets.

[0058] Example 1:

[0059] Including: Step 1: Smelting, which involves sending the raw materials into a smelting furnace for smelting and casting;

[0060] Step 2: Hydrogen crushing and air jet milling. Utilizing the hydrogen absorption properties of rare earth metal compounds, the neodymium iron boron alloy is placed in a hydrogen environment. The hydrogen will enter the alloy along the neodymium-rich phase thin layer, causing it to expand and break, thus turning the thin sheet into coarse powder. The coarse powder is then processed into fine powder using an air jet mill.

[0061] Step 3: Molding. The fine powder is placed in the mold of the pressing and molding machine for pressing and molding. Specifically, when adding fine powder to the lower mold frame 2, the drive motor 63 is started, and the valve at the bottom of the feeding cylinder 68 is opened. The fine powder is automatically injected into the lower mold frame 2 under its own weight. By expanding the feeding point area of ​​the feeding cylinder 68, the feeding posture of the feeding cylinder 68 is further diversified, so that the fine powder can be evenly distributed. This prepares for the subsequent sintering process.

[0062] Step 4: Sintering. The formed product is placed in a sintering furnace for sintering at a sintering temperature of 1025℃ for 4.0 hours, followed by aging treatment at 500℃ for 5 hours. The product is then removed from the sintering furnace, thus producing a neodymium iron boron magnet. Samples of the sintered neodymium iron boron magnets are then taken for testing.

[0063] As a further aspect of the present invention: the air jet mill processes the coarse powder twice.

[0064] The coarse powder that has been hydrogenated was subjected to a first air jet milling process to obtain 3.5μm powder;

[0065] During the second air jet milling, polyacrylic acid dispersant was added at a ratio of 0.05 wt% of powder to obtain powder with an average particle size of ≤2.5 μm.

[0066] Example 2:

[0067] The compression molding machine includes:

[0068] A base 1, on which a lower mold frame 2 is provided, and an upper template 4 is connected to the base 1 via a hydraulic lifting column 3;

[0069] Pressure block 5, which is fixed to the bottom of the upper template 4 and is correspondingly set to the lower template 2;

[0070] The material spreading mechanism 6 is used to evenly spread material onto the lower mold frame 2.

[0071] The fabric-making mechanism 6 includes:

[0072] A support frame 61 is fixedly mounted on the base 1.

[0073] A lead screw 62 is rotatably mounted on the side of the upright frame 61 facing the lower mold and is connected to a drive motor 63 fixedly mounted on the upright frame 61.

[0074] A slide rod 64 is arranged parallel to the lead screw 62 and is fixedly mounted on the upright 61, and is located on the same side as the lead screw 62;

[0075] A slide block 65 is sleeved on the lead screw 62 and the slide rod 64;

[0076] A swing arm 66, one end of which is fixedly provided with a rotating shaft 67, which is rotatably connected to the slide block 65, and the other end is provided with a fabric cylinder 68;

[0077] A rotating motor 69 is fixedly mounted on the bottom surface of the slide 65 and is connected to the rotating shaft 67 for transmission.

[0078] To address the issue of cracks and defects in pressed products caused by uneven powder distribution and varying powder density within the lower mold frame 2 during the pressing process, this embodiment incorporates a powder distribution mechanism 6. When fine powder needs to be added to the lower mold frame 2, the drive motor 63 is activated, rotating the lead screw 62. The lead screw 62 slide block 65 forms a lead screw 62 slider pair, thereby moving the slide block 65 from the edge towards the center. The rotation motor 69 is then activated, rotating the shaft 67. The shaft 67 causes the swing arm 66 to swing towards the center until the powder distribution cylinder 68 on the swing arm 66 aligns with the lower mold frame 2. The valve at the bottom of the powder distribution cylinder 68 is then opened, allowing the fine powder to be automatically injected into the lower mold frame 2 under its own weight. Simultaneously, the rotation motor 69 causes the powder distribution cylinder 68 to deflect slightly, achieving multi-point powder distribution. This expands the distribution area, making it more uniform and reducing the occurrence of a high center and low periphery due to a fixed distribution point.

[0079] The fabric mechanism 6 is unfolded during operation and folded when not in operation by the cooperation of the lead screw 62 slider transmission pair and the rotating motor 69, so as to avoid interference with the pressing and molding process.

[0080] As a further aspect of the present invention: the swing arm 66 is provided with a swing component 7, which is used to change the posture of the fabric cylinder 68 when the fabric is being laid.

[0081] As a further aspect of the present invention: the swing component 7 includes:

[0082] A slide groove 71 is formed on the side of the rocker arm 66 away from the slide block 65;

[0083] The limiting sleeve 72 has a diameter larger than the groove diameter of the sliding groove 71, and the limiting sleeve 72 is rotatably connected to the fabric cylinder 68.

[0084] An electric push rod 73 is fixed on the swing arm 66, and the telescopic end of the electric push rod 73 is detachably and fixedly connected to the limiting sleeve 72.

[0085] In this embodiment, in order to expand the material distribution point of the material cylinder 68, a swing component 7 is installed on the swing arm 66. The electric push rod 73 pushes the limiting sleeve 72 to slide back and forth in the slide groove 71, allowing the material cylinder 68 on the limiting sleeve 72 to move back and forth in the slide groove 71. With the small swing of the swing arm 66, the material distribution point range of the material cylinder 68 can be further expanded, and the material distribution posture of the material cylinder 68 can be further diversified, thereby achieving the purpose of uniform material distribution, reducing the probability of product cracks caused by uneven material distribution and excessive differences in material density in different areas, thereby improving the quality of the pressed product and facilitating subsequent sintering treatment.

[0086] In this embodiment, the shape of the chute 71 can be a straight chute, an arc chute, or a combination of both. Compared with a straight chute, an arc chute allows for more varied fabric distribution points in the fabric cylinder 68, which is beneficial for uniform fabric distribution.

[0087] Example 3:

[0088] The base 1 has a movable groove 8. The length of the movable groove 8 facing the upright 61 is greater than the length of the lower mold frame 2. The fabric cylinder 68 is equipped with a linkage component 9. The linkage component 9 drives the lower mold frame 2 to move within the movable groove 8 while the fabric is being laid.

[0089] The linkage component 9 includes:

[0090] Gear ring 91, the gear ring 91 is fixed on the outer wall of the fabric cylinder 68;

[0091] A rack 92 is fixedly provided at the bottom of the slide groove 71, and the rack 92 meshes with a gear;

[0092] A protrusion 93 is installed on the outer side of the bottom of the fabric cylinder 68, and the outer diameter of the protrusion 93 is larger than the width of the lower mold frame 2.

[0093] In this embodiment, through the cooperation of the gear and gear ring 91 in the linkage component 9, when the slide groove 71 is a straight groove, during the reciprocating movement of the material cylinder 68 and the slide groove 71, the gear rack 92 drives the material cylinder 68 to rotate. The material cylinder 68 drives the bottom protrusion 93 to rotate. Since the outer diameter of the protrusion 93 is larger than the width of the lower mold frame 2, it pushes the lower mold frame 2 to move towards the movable groove 8. When the protrusion 93 rotates to the other side, it pushes the lower mold frame 2 back to its original position. By changing the position of the lower mold frame 2 during the material feeding process, the lower mold frame 2 moves back and forth while the material feeding point of the material cylinder 68 remains unchanged, thereby relatively changing the material feeding point and further enhancing the uniformity of the material feeding. At the same time, during the reciprocating movement of the lower mold frame 2, the internal material is shaken, which reduces the gap between the materials after relative movement, further promoting the uniformity of the material and improving the quality of the pressed product.

[0094] The bottom outer side of the fabric cylinder 68 is provided with a limiting block 94, and the limiting block 94 is provided with a limiting groove 95. The protrusion 93 is slidably installed in the limiting groove 95. An electromagnet 96 is installed in the limiting groove 95. A permanent magnet 97 is embedded and connected to the protrusion 93. The electromagnet 96 and the permanent magnet 97 are positioned opposite each other.

[0095] In this embodiment, the switching between the on and off states of the electromagnet 96 achieves the change between demagnetization and magnetization. When the protrusion 93 is working, the electromagnet 96 is energized and magnetized, thereby repelling the permanent magnet 97 downwards. The permanent magnet 97 drives the protrusion 93 to move downwards within the limiting groove 95, overcoming the support spring at the bottom of the limiting groove 95. This allows the protrusion 93 to fall from a high position into the lower mold frame 2, enabling the protrusion 93 to push the lower mold frame 2 when it rotates circumferentially. Once the work is completed, the electromagnet 96 is de-energized and demagnetized, and the support spring elastically resets, thereby pushing the protrusion 93 back to the top position of the limiting groove 95. At this time, the protrusion 93 detaches from the lower mold frame 2 and can be pushed out of the working area of ​​the upper mold plate 4 along with the cloth cylinder 68 and the swing arm 66. By making the position of the protrusion 93 adjustable, the switching efficiency between the working and non-working states of the protrusion 93 is facilitated.

[0096] The working principle of the compression molding machine in this invention:

[0097] To address the issue of cracks and defects in pressed products caused by uneven powder distribution and varying powder density within the lower mold frame 2 during the pressing process, this embodiment incorporates a powder distribution mechanism 6. When fine powder needs to be added to the lower mold frame 2, the drive motor 63 is activated, rotating the lead screw 62. The lead screw 62 slide block 65 forms a lead screw 62 slider pair, thereby moving the slide block 65 from the edge towards the center. The rotation motor 69 is then activated, rotating the shaft 67. The shaft 67 causes the swing arm 66 to swing towards the center until the powder distribution cylinder 68 on the swing arm 66 aligns with the lower mold frame 2. The valve at the bottom of the powder distribution cylinder 68 is then opened, allowing the fine powder to be automatically injected into the lower mold frame 2 under its own weight. Simultaneously, the rotation motor 69 causes the powder distribution cylinder 68 to deflect slightly, achieving multi-point powder distribution. This expands the distribution area, making it more uniform and reducing the occurrence of a high center and low periphery due to a fixed distribution point.

[0098] The fabric mechanism 6 is expanded during operation and folded when not in operation by the cooperation of the lead screw 62 slider transmission pair and the rotating motor 69, so as to avoid interference with the pressing and molding process.

[0099] To expand the material distribution range of the material feeding cylinder 68, a swing assembly 7 is installed on the swing arm 66. The electric push rod 73 pushes the limiting sleeve 72 to slide back and forth in the slide groove 71, allowing the material feeding cylinder 68 on the limiting sleeve 72 to move back and forth in the slide groove 71. Combined with the small-amplitude swing of the swing arm 66, the material feeding range of the material feeding cylinder 68 can be further expanded, and the material feeding posture of the material feeding cylinder 68 can be further diversified, thereby achieving the purpose of uniform material feeding. This reduces the probability of product cracking due to uneven material feeding and excessive differences in material density in different areas, thereby improving the quality of the pressed product and facilitating subsequent sintering.

[0100] Furthermore, through the cooperation of gears and gear rings 91 in the linkage component 9, when the slide groove 71 is a straight groove, during the reciprocating movement of the material cylinder 68 and the slide groove 71, the gear rack 92 drives the material cylinder 68 to rotate. The material cylinder 68 drives the bottom protrusion 93 to rotate. Since the outer diameter of the protrusion 93 is larger than the width of the lower mold frame 2, it pushes the lower mold frame 2 to move towards the movable groove 8. When the protrusion 93 rotates to the other side, it pushes the lower mold frame 2 back to its original position. By changing the position of the lower mold frame 2 during the material feeding process, the lower mold frame 2 moves back and forth while the material feeding point of the material cylinder 68 remains unchanged, thereby relatively changing the material feeding point and further enhancing the uniformity of the material feeding. At the same time, during the reciprocating movement of the lower mold frame 2, the internal material is shaken, which reduces the gap between the materials after relative movement, further promoting the uniformity of the material and improving the quality of the pressed product.

[0101] When the protrusion 93 is working, the electromagnet 96 is energized and magnetized, thereby repelling the permanent magnet 97 downward. The permanent magnet 97 drives the protrusion 93 to move downward within the limiting groove 95, overcoming the support spring at the bottom of the limiting groove 95. This allows the protrusion 93 to fall from a height into the lower mold frame 2, so that the protrusion 93 can push the lower mold frame 2 when it rotates around. Once the work is completed, the electromagnet 96 is de-energized and demagnetized, and the support spring elastically resets, thereby pushing the protrusion 93 back to the top position of the limiting groove 95. At this time, the protrusion 93 is separated from the lower mold frame 2 and can be pushed out of the working area of ​​the upper mold plate 4 along with the cloth cylinder 68 and the swing arm 66.

[0102] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A manufacturing process for high-magnetic-performance sintered NdFeB magnets, characterized in that, include: Step 1: Melting, the raw materials are sent into the melting furnace for melting and casting; Step 2: Hydrogen crushing and air jet milling. Utilizing the hydrogen absorption properties of rare earth metal compounds, the neodymium iron boron alloy is placed in a hydrogen environment. The hydrogen will enter the alloy along the neodymium-rich phase thin layer, causing it to expand and break, thus turning the thin sheet into coarse powder. The coarse powder is then processed into fine powder using an air jet mill. Step 3: Molding. Place the fine powder in the mold of the pressing and molding machine and press it into shape. Specifically, when adding fine powder to the lower mold frame (2), start the drive motor (63) and open the bottom valve of the cloth cylinder (68). The fine powder is automatically injected into the lower mold frame (2) under its own weight. By expanding the feeding point area of ​​the feeding cylinder (68), the feeding posture of the feeding cylinder (68) is further diversified, so that the fine powder can be evenly distributed; in preparation for subsequent sintering treatment; Step 4: Sintering. The formed product is placed in a sintering furnace for sintering at a sintering temperature of 1020-1035℃ for 3.5-5.0 hours. Then, it is aged at 450-600℃ for 4-6 hours. The product is then removed from the sintering furnace, thus producing a neodymium iron boron magnet. The sintered neodymium iron boron magnet is then sampled and tested. The compression molding machine includes: A base (1) is provided on which a lower mold frame (2) is provided, and an upper template (4) is connected to the base (1) by a hydraulic lifting column (3); Pressure block (5), the pressure block (5) is fixed to the bottom of the upper template (4) and is correspondingly set with the lower template frame (2); The material feeding mechanism (6) is used to uniformly feed material onto the lower mold frame (2); The fabric mechanism (6) includes: A support frame (61) is fixedly mounted on the base (1); A lead screw (62) is rotatably mounted on the side of the upright frame (61) facing the lower mold and is connected to a drive motor (63) fixedly mounted on the upright frame (61). A slide rod (64) is arranged parallel to the lead screw (62), and the slide rod (64) is fixedly mounted on the upright (61) and located on the same side as the lead screw (62); A slide (65) is sleeved on the lead screw (62) and the slide rod (64); A swing arm (66) is provided with a rotating shaft (67) fixed at one end, the rotating shaft (67) being rotatably connected to the slide (65), and a fabric cylinder (68) at the other end; A rotating motor (69) is fixedly mounted on the bottom surface of the slide (65) and is connected to the rotating shaft (67) for transmission. The swing arm (66) is provided with a swing component (7), which is used to change the posture of the fabric cylinder (68) when the fabric is being laid; The swing assembly (7) includes: A groove (71) is formed on the side of the rocker arm (66) away from the slide block (65); A limiting sleeve (72) is provided, the diameter of which is larger than the groove diameter of the slide (71), and the limiting sleeve (72) is rotatably connected to the fabric cylinder (68). An electric push rod (73) is fixed on the swing arm (66), and the telescopic end of the electric push rod (73) is detachably and fixedly connected to the limiting sleeve (72); The base (1) is provided with a movable groove (8), the length of the movable groove (8) facing the upright (61) is greater than the length of the lower mold frame (2), and a linkage component (9) is installed on the fabric cylinder (68). The linkage component (9) drives the lower mold frame (2) to move in the movable groove (8) while the fabric is being laid. The linkage component (9) includes: A toothed ring (91) is fixed on the outer wall of the fabric cylinder (68); A rack (92) is fixedly provided at the bottom of the slide groove (71), and the rack (92) meshes with a gear; A protrusion (93) is installed on the outer side of the bottom of the fabric cylinder (68), and the outer diameter of the protrusion (93) is greater than the width of the lower mold frame (2).

2. The manufacturing process of high magnetic performance sintered NdFeB according to claim 1, characterized in that, The air jet mill processes the coarse powder twice. The coarse powder that has been hydrogenated is subjected to a first air jet milling process to obtain 3-4 μm powder. During the second air jet milling, a dispersant was added at a ratio of 0.03-0.05 wt% of the powder to obtain powder with an average particle size ≤2.5 μm. The dispersant is polyacrylic acid.

3. The manufacturing process for high-magnetic-performance sintered NdFeB according to claim 1, characterized in that, The bottom outer side of the fabric cylinder (68) is provided with a limiting block (94), the limiting block (94) is provided with a limiting groove (95), the protrusion (93) is slidably installed in the limiting groove (95), an electromagnet (96) is installed in the limiting groove (95), a permanent magnet (97) is embedded and connected on the protrusion (93), and the electromagnet (96) and the permanent magnet (97) are positioned opposite each other.

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