Preparation equipment and preparation method for efficiently sintering neodymium-iron-boron magnet

Abstract

The invention discloses preparation equipment and a preparation method of an efficient sintered neodymium-iron-boron magnet, and belongs to the technical field of neodymium-iron-boron magnet preparation.The preparation equipment comprises a tank body, the tank body is installed on a support in a sliding mode, a feeding port is formed in the tank body, a stirring cavity communicated with the feeding port is formed in the tank body, and a stirring shaft is rotatably installed in the stirring cavity; the stirring shaft is hollow, one end of the stirring shaft axially extends out of the stirring cavity, the end, extending out of the stirring cavity, of the stirring shaft is fixedly connected with an inflation mechanism, a plurality of stirring rods are arranged on the stirring shaft in a circumferential array mode with the axis of the stirring shaft as the center, and a plurality of air holes communicated with the interior of the stirring shaft are formed in the stirring rods. The bottom wall of the tank body is provided with a vibration chamber communicated with the stirring cavity and a discharge port communicated with the vibration chamber, a pneumatic vibrator is installed in the vibration chamber, a mold is installed below the tank body, and a mold cavity located below the discharge port is formed in the mold. By optimizing the hydrogen demolishing, powdering and forming processes, the product cracking rate is reduced, and the appearance yield is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of NdFeB magnet preparation, and in particular relates to a preparation device and a preparation method for a high-efficiency sintered NdFeB magnet. Background Art

[0002] As an important representative of rare earth permanent magnet materials, NdFeB magnets have high magnetic energy product, high coercive force and good mechanical properties, and are widely used in motors, sensors, speakers and other fields. However, the traditional preparation process of sintered NdFeB magnets is complicated, requiring multiple steps such as smelting, hydrogen cracking, powder making, orientation pressing, isostatic pressing, sintering, etc., which not only has high production costs but also low production efficiency. Therefore, it is of great significance to develop an efficient and low-cost one-step forming sintered NdFeB magnet preparation method.

[0003] In the prior art, for example, a Chinese patent application numbered 202111542152.0 discloses a method for preparing a one-step formed sintered NdFeB magnet. However, its active stirring device still has uneven stirring, resulting in poor powder uniformity. In addition, the powder adding and molding mechanism has high requirements for mold installation, and the actual operation and use are relatively complicated.

[0004] Therefore, it is necessary to provide a preparation device and a preparation method for high-efficiency sintered NdFeB magnets to solve the above problems. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a preparation device and a preparation method for a high-efficiency sintered NdFeB magnet, so as to solve the problem in the prior art that insufficient stirring leads to poor uniformity of powder.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation device for a high-efficiency sintered NdFeB magnet, comprising a tank body, which is slidably mounted on a bracket, a feed port is provided on the tank body, a stirring chamber connected to the feed port is provided in the tank body, a stirring shaft is rotatably mounted in the stirring chamber, the interior of the stirring shaft is hollow, one end of the stirring shaft axially extends out of the stirring chamber, an inflation mechanism is fixedly connected to the end of the stirring shaft extending out of the stirring chamber, a plurality of stirring rods are arranged in a circumferential array with the stirring shaft axis as the center on the stirring shaft, a plurality of air holes connected to the interior of the stirring shaft are arranged on the stirring rods, a vibration chamber connected to the stirring chamber and a discharge port connected to the vibration chamber are provided on the bottom wall of the tank body, a pneumatic vibrator is installed in the vibration chamber, a mold is installed below the tank body, and a mold cavity located below the discharge port is provided in the mold.

[0008] Furthermore, a reciprocating screw is rotatably mounted on the bracket, the tank body is threadedly connected to the reciprocating screw, and one end of the reciprocating screw is fixedly connected to a driving mechanism for driving the reciprocating screw to rotate.

[0009] Furthermore, the stirring chamber is connected with the vibration chamber through a blanking port, wherein a plurality of blanking ports are circumferentially arranged with the axis of the stirring chamber as the center, a partition is rotatably installed in the tank body, and a plurality of through holes corresponding to the blanking ports are arranged on the partition. Rotating the partition so that the through holes are misaligned or correspond to the blanking port can separate or connect the stirring chamber and the vibration chamber.

[0010] The cam is fixedly mounted on the bracket, the cam is provided with a sliding hole, the mold is arranged below the sliding hole, the discharge port end of the tank body is slidably mounted in the sliding hole, and sliding grooves are arranged on the two side walls opposite to each other in the sliding direction of the sliding hole, a rack is fixedly mounted in the sliding groove, a screen that can slide along the axial direction of the discharge port is slidably mounted in the discharge port, and an annular slide groove connected with the discharge port is provided on the tank body, and the screen is limited and slidably mounted in the annular slide groove, and an elastic member is fixedly connected between the screen and the bottom wall of the annular slide groove, and two symmetrically arranged cams are rotatably mounted in the annular slide groove, and the cam is abutted against the bottom wall of the screen, one end of the cam is fixedly connected to a connecting rod, and one end of the connecting rod extends to the slide groove and is fixedly connected to a gear meshing with the rack, and the connecting rod is rotatably connected to the tank body.

[0011] Furthermore, a pressure relief valve is provided on the tank body.

[0012] Furthermore, a bottom plate is slidably installed in the mold, and the sliding bottom plate can adjust the height of the mold cavity. A powder scraping sponge that abuts against the inner wall of the mold cavity is fixedly arranged on the peripheral wall of the bottom plate.

[0013] A method for preparing a high-efficiency sintered NdFeB magnet preparation device comprises the following steps:

[0014] Melting: Clean the surface of the raw materials and put them into the melting furnace for melting to obtain alloy sheets with a thickness of 0.2mm-0.3mm;

[0015] Hydrogen breaking and powder making: The alloy flakes are made into coarse powder by hydrogen breaking process, and the coarse powder is fed into the tank through the feed port. At this time, the partition is rotated to make the through hole and the blanking port misaligned; then the feed port is closed, the stirring shaft is rotated by the driving motor, and the inflation mechanism is started to inflate the stirring shaft, wherein the stirring time is 30 minutes;

[0016] Molding: After the mixing is completed, the partition is rotated to make the through hole correspond to the drop opening to carry out the powder distribution work, so that the powder falls into the vibration chamber, and the pneumatic vibrator is used to break up the powder in the vibration chamber and drop it on the screen. At this time, the drive mechanism is started to drive the reciprocating screw to rotate, so that the tank body slides back and forth in the limit slide groove, so that the powder is spread layer by layer in the mold cavity; a one-time molding mold is used here to press the powder into a density of 4.4g / cm under the magnetic field orientation. 3 Greenware;

[0017] Sintering: The green body is sent into a vacuum sintering furnace in a low oxygen environment for sintering and tempering treatment.

[0018] Furthermore, during the forming process, when the tank body slides back and forth along the limiting slide groove, the tank body drives the connecting rod to move synchronously, thereby driving the gear to move along the rack to rotate the gear, thereby rotating the cam. The rotation of the cam can cause the screen to move back and forth up and down to generate a vibration force on the screen.

[0019] Furthermore, during the powder distribution process, the tank body moves in sections, with the speed of the first section being 30 mm / s, the second section being 50 mm / s, and the third section being 70 mm / s.

[0020] Furthermore, before the powder is applied, the bottom plate is arranged close to the top wall of the mold. During the powder application process, the bottom plate is driven to move downward, and the bottom plate descends at a speed of 5 mm / s.

[0021] The beneficial effects of the present invention are as follows: under the condition of the same ingredients, the present invention optimizes the hydrogen cracking, powder making and molding processes, so that the product cracking rate can be achieved to 0.05%, the appearance yield is 99%, and the operation is simple, and it is convenient to replace the mold to improve efficiency. At the same time, the appearance yield is high and the production efficiency is high.

[0022] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0024] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention;

[0025] Figure 2 It is a cross-sectional view of the overall structure of an embodiment of the present invention;

[0026] Figure 3 This is a cross-sectional view of the screen installation according to an embodiment of the present invention.

[0027] The markings in the accompanying drawings are as follows: tank body 1, feed port 101, stirring chamber 102, vibration chamber 103, discharge port 104, blanking port 105, annular chute 106, stirring shaft 2, stirring rod 3, air hole 301, mold 4, mold cavity 401, bottom plate 402, scraper sponge 403, bracket 5, reciprocating screw 501, partition 6, through hole 601, fixed plate 7, sliding hole 701, chute 702, rack 703, screen 8, elastic member 801, cam 802, connecting rod 803, gear 804. DETAILED DESCRIPTION

[0028] like Figures 1 to 3 As shown, the present invention provides a preparation device for high-efficiency sintered NdFeB magnets, comprising: a bracket 5, a tank body 1 is slidably mounted on the bracket 5, a feed port 101 is arranged on the tank body 1, wherein two feed ports 101 are arranged, respectively used to feed coarse powder and additives; a stirring chamber 102 connected to the feed port 101 is arranged in the tank body 1, a stirring shaft 2 is rotatably mounted in the stirring chamber 102, the stirring shaft 2 is driven by a driving motor, the stirring shaft 2 is hollow inside, one end of the stirring shaft 2 axially extends out of the stirring chamber 102, an inflation mechanism is fixedly connected to the end of the stirring shaft 2 extending out of the stirring chamber 102, the inflation mechanism is a conventional technical means in the field, and will not be described in detail here; a plurality of circumferential arrays are arranged on the stirring shaft 2 with the axis of the stirring shaft 2 as the center. A stirring rod 3 is provided with a plurality of air holes 301 connected to the inside of the stirring shaft 2, and a filter is provided in the air holes 301 to prevent powder from entering the stirring rod 3 through the air holes 301. A vibration chamber 103 connected to the stirring chamber 102 and a discharge port 104 connected to the vibration chamber 103 are provided at the bottom of the tank body 1. A pneumatic vibrator is installed in the vibration chamber 103. The pneumatic vibrator is a device using compressed air as a power source. The vibration frequency is controlled by adjusting the air flow rate to achieve the purpose of vibrating the powder in the vibration chamber 103 so as to make the powder uniform. The pneumatic vibrator is a conventional technical means in this field and will not be described here. A mold 4 is installed below the tank body 1, and a mold cavity 401 located below the discharge port 104 is provided in the mold 4. Among them, a pressure relief valve (not shown in the figure) is provided on the tank body 1. During the inflation and stirring process, the feed port 101 needs to be closed to prevent the powder from flying out of the feed port 101 during the inflation process, and the pressure in the tank body is balanced through the pressure relief valve.

[0029] A reciprocating screw 501 is rotatably mounted on the bracket 5, the tank body 1 is threadedly connected to the reciprocating screw 501, and one end of the reciprocating screw 501 is fixedly connected to a driving mechanism for driving the reciprocating screw 501 to rotate, and the driving mechanism is a motor. The driving mechanism is started to rotate the reciprocating screw 501, thereby driving the tank body 1 to reciprocate, so that the powder falling from the discharge port 104 is spread layer by layer in the mold cavity 401.

[0030] The stirring chamber 102 is connected with the vibration chamber 103 through a feeding port 105, wherein the feeding port 105 is arranged circumferentially with the axis of the stirring chamber 102 as the center, and a partition 6 is rotatably installed in the tank body 1, and a plurality of through holes 601 corresponding to the feeding port 105 are arranged on the partition 6. The stirring chamber 102 and the vibration chamber 103 can be separated or connected by rotating the partition 6 so that the through holes 601 are misaligned or corresponded with the feeding port 105; when the powder falls into the stirring chamber 102, the partition 6 is first rotated so that the through holes 601 The stirring chamber 102 is offset from the material discharge port 105 so that the stirring chamber 102 is in a closed state, and the powder will always be in the stirring chamber 102. The stirring shaft 2 is rotated to rotate the stirring rod 3, so that the material in the stirring chamber 102 is stirred, and the stirring time can be increased to ensure the uniformity of stirring. While stirring, gas is filled into the stirring shaft 2 through the inflation mechanism, and then sprayed out from the air hole 301 on the stirring rod 3, so that the coarse powder entering the tank body 1 is broken up while stirring, and the stirring effect of the coarse powder and the additive is improved.

[0031] The bracket 5 is fixedly provided with a fixing plate 7, and the fixing plate 7 is provided with a sliding hole 701. The discharge port 104 end of the tank body 1 is slidably installed in the sliding hole 701. The sliding hole 701 is provided with sliding grooves 702 on both side walls opposite to each other along the sliding direction. A rack 703 is fixedly installed in the sliding groove 702. A screen 8 that can slide along the axial direction of the discharge port 104 is slidably installed in the discharge port 104. The tank body 1 is provided with an annular sliding groove 106 that is connected to the discharge port 104. The screen 8 is limited to slide It is rotatably installed in the annular slide groove 106, and an elastic member 801 is fixedly connected between the screen 8 and the bottom wall of the annular slide groove 106. The elastic member 801 is a spring. Two symmetrically arranged cams 802 are rotatably installed in the annular slide groove 106, and the cams 802 are against the bottom wall of the screen 8. One end of the cam 802 is fixedly connected to a connecting rod 803, and one end of the connecting rod 803 extends into the slide groove 702 and is fixedly connected to a gear 804 meshing with the rack 703. The connecting rod 803 is rotatably connected to the tank body 1. In this solution, when the driving mechanism drives the reciprocating screw 501 to rotate so that the tank body 1 moves back and forth, the tank body 1 drives the connecting rod 803 to move synchronously, thereby driving the gear 804 to move along the rack 703 to rotate the gear 804, thereby rotating the cam 802. The rotation of the cam 802 can cause the screen 8 to move back and forth up and down so that the screen 8 generates a vibration force, so that the powder falling from the discharge port 104 is further broken up, thereby improving the uniformity of the powder distribution.

[0032] A bottom plate 402 is slidably mounted in the mold 4. The sliding bottom plate 402 can adjust the height of the mold cavity 401. A powder scraping sponge 403 is fixedly mounted on the peripheral wall of the bottom plate 402 to abut against the inner wall of the mold cavity 401. Before powder spreading, the bottom plate 402 is arranged close to the top wall of the mold 4. During powder spreading, the bottom plate 402 is driven to move downward, and the powder scraping sponge 403 scrapes the powder on the inner wall of the mold cavity 401. At the same time, a release agent is evenly sprayed on the bottom plate 402, which is conducive to reducing the amount of release agent used, reducing powder sticking, making the inner wall smoother, and increasing the mold life while reducing the crack rate.

[0033] The present invention also provides a method for preparing a high-efficiency sintered NdFeB magnet, which comprises the following steps:

[0034] Melting: Clean the surface of the raw materials and put them into the melting furnace for melting to obtain alloy sheets with a thickness of 0.2mm-0.3mm;

[0035] Hydrogen rupture and powder making: The alloy flakes are made into coarse powder by hydrogen rupture process, and the coarse powder is fed into the tank body 1 through the feed port 101. At this time, the partition plate 6 is rotated to make the through hole 601 and the blanking port 105 misaligned; then the feed port 101 is closed, the stirring shaft 2 is rotated by the driving motor, and the inflation mechanism is started to inflate the stirring shaft 2, wherein the stirring time is 30 minutes;

[0036] Molding: After the stirring is completed, the partition plate 6 is rotated to make the through hole 601 correspond to the drop opening 105, so that the powder falls into the vibration chamber 103, and the powder falling into the vibration chamber 103 is broken up by the pneumatic vibrator and falls on the screen 8. At this time, the driving mechanism is started to drive the reciprocating screw 501 to rotate, so that the tank body 1 slides back and forth in the limiting slide groove 106, so that the powder is spread layer by layer in the mold cavity 401; wherein, during the reciprocating sliding of the tank body 1 along the limiting slide groove 106, the tank body 1 drives the connecting rod 803 to move synchronously, thereby driving the gear 804 to move along the rack 703 so that the gear 80 4 rotates, thereby rotating the cam 802, and the rotation of the cam 802 can make the screen 8 move up and down reciprocatingly so that the screen 8 generates a vibration force; wherein, during the powder distribution process, the tank body 1 moves in sections, the speed of the first section is 30mm / s, the second section is 50mm / s, and the third section is 70mm / s; wherein, before the powder distribution, the bottom plate 402 is arranged close to the top wall of the mold 4, and during the powder distribution process, the bottom plate 402 is driven to move downward, and the descending speed of the bottom plate 402 is 5mm / s. Here, a special mold for one-time molding is used, and the powder is pressed into a density of 4.4g / cm under the magnetic field orientation. 3 Greenware;

[0037] Sintering: The green body is sent into a vacuum sintering furnace in a low oxygen environment for sintering and tempering treatment.

[0038] Embodiment 2: Referring to Embodiment 1, the difference between Embodiment 2 and Embodiment 1 is that during the hydrogen cracking and powder making process, the aeration mechanism is not started to aerate the stirring shaft;

[0039] Embodiment 3: Referring to Embodiment 1, the difference between Embodiment 3 and Embodiment 1 is that: during the forming process, the pneumatic vibrator and the screen 8 are eliminated;

[0040] Embodiment 4: Referring to Embodiment 1, the difference between Embodiment 4 and Embodiment 1 is that a fixed mold cavity 401 is adopted, that is, the bottom plate 402 is fixedly arranged at a preset height before powder distribution, so that the volume of the mold cavity 401 remains unchanged;

[0041] Comparative example: Referring to Example 1, the difference between the comparative example and Example 1 is that during the hydrogen pulverization and powder making process, the inflation mechanism is not started to inflate the stirring shaft; during the molding process, the pneumatic vibrator and the screen 8 are cancelled; a fixed mold cavity 401 is used, that is, the bottom plate 402 is fixedly set at a preset height before powder distribution to keep the volume of the mold cavity 401 unchanged.

[0042] According to the above examples, high-efficiency sintered NdFeB magnets were prepared respectively, and the data in different preparation methods were statistically analyzed to obtain the following table:

[0043] name Br HkDJ oxygen carbon Cracking rate Appearance yield Example 1 12.78 17.11 550 500 0.05％ 99％ Example 2 12.7 16.98 660 680 0.10％ 98％ Example 3 12.67 16.95 670 680 4％ 95％ Example 4 12.63 17 690 800 9.5％ 82％ Comparative Example 12.51 17.01 818 900 10％ 80％

[0044] It can be seen from the above table that the product produced by the method disclosed in this scheme has a final cracking rate of 0.05% and an appearance yield of 99%. The cracking rate and appearance yield are improved, and the oxygen and carbon contents are reduced. Referring to Example 2, if the hydrogen cracking and the inflation into the stirring shaft during the powder making process are cancelled, the cracking rate will be increased to 0.1%, and the appearance yield and the oxygen and carbon content will be increased. Referring to Example 3, if the setting of the pneumatic vibrator and the screen 8 in the molding process of this scheme is cancelled, the cracking rate will be increased to 4%, and the appearance yield will be reduced. Referring to Example 4, if a fixed mold cavity 401 is used, the cracking rate will be increased to 9.5%, and the carbon content will increase significantly, and the appearance yield will decrease. Referring to the comparative example, the conventional scheme is adopted for preparation, that is, all the above-mentioned optimization schemes are cancelled, which will cause the cracking rate to be increased to 10%, and the oxygen and carbon contents will be greatly increased. It can be seen that the solution provided by the present invention, under the condition of the same ingredients, can achieve a cracking rate of 0.05% through optimization and innovative preparation process, and is simple to operate and convenient for replacing molds to improve efficiency. At the same time, it has a high appearance yield and high production efficiency.

[0045] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A preparation device for high-efficiency sintered NdFeB magnets, comprising a tank body, characterized in that: The tank body is slidably mounted on the bracket, and a feed port is provided on the tank body. A stirring chamber connected with the feed port is provided in the tank body, a stirring shaft is rotatably mounted in the stirring chamber, the interior of the stirring shaft is hollow, one end of the stirring shaft axially extends out of the stirring chamber, an inflation mechanism is fixedly connected to the end of the stirring shaft extending out of the stirring chamber, a plurality of stirring rods are arranged in a circumferential array on the stirring shaft with the axis of the stirring shaft as the center, a plurality of air holes connected with the interior of the stirring shaft are arranged on the stirring rods, a vibration chamber connected with the stirring chamber and a discharge port connected with the vibration chamber are provided on the bottom wall of the tank body, a pneumatic vibrator is installed in the vibration chamber, a mold is installed below the tank body, and a mold cavity located below the discharge port is provided in the mold.

2. The preparation equipment of high efficiency sintered NdFeB magnet according to claim 1, characterized in that: A reciprocating screw rod is rotatably mounted on the bracket, the tank body is threadedly connected to the reciprocating screw rod, and one end of the reciprocating screw rod is fixedly connected to a driving mechanism for driving the reciprocating screw rod to rotate.

3. The preparation equipment of high efficiency sintered NdFeB magnet according to claim 2, characterized in that: The stirring chamber is connected with the vibration chamber through a blanking port, wherein a plurality of blanking ports are circumferentially arranged with the axis of the stirring chamber as the center, a partition is rotatably installed in the tank body, and a plurality of through holes corresponding to the blanking ports are arranged on the partition. The stirring chamber and the vibration chamber can be separated or connected by rotating the partition so that the through holes are misaligned or correspond to the blanking port.

4. The preparation equipment of high efficiency sintered NdFeB magnet according to claim 3, characterized in that: The cam is fixedly mounted on the bracket, and a sliding hole is provided on the fixing plate, and the mold is arranged below the sliding hole, and the discharge port end of the tank body is slidably mounted in the sliding hole, and sliding grooves are provided on two side walls opposite to each other in the sliding hole along the sliding direction, and a rack is fixedly mounted in the sliding groove, and a screen that can slide along the axial direction of the discharge port is slidably mounted in the discharge port. The tank body is provided with an annular slide groove connected with the discharge port, and the screen is limited and slidably mounted in the annular slide groove, and an elastic member is fixedly connected between the screen and the bottom wall of the annular slide groove, and two symmetrically arranged cams are rotatably mounted in the annular slide groove, and the cam is abutted against the bottom wall of the screen, and one end of the cam is fixedly connected to a connecting rod, and one end of the connecting rod extends to the slide groove and is fixedly connected to a gear meshing with the rack, and the connecting rod is rotatably connected to the tank body.

5. The preparation equipment of high efficiency sintered NdFeB magnet according to claim 4, characterized in that: The tank body is provided with a pressure relief valve.

6. The preparation equipment of high efficiency sintered NdFeB magnet according to claim 5, characterized in that: A bottom plate is slidably installed in the mold, and the sliding bottom plate can adjust the height of the mold cavity. A powder scraping sponge that abuts against the inner wall of the mold cavity is fixedly arranged on the peripheral wall of the bottom plate.

7. The method for preparing the high-efficiency sintered NdFeB magnet according to any one of claims 1 to 6, characterized in that: The following steps are involved: Melting: Clean the surface of the raw materials and put them into the melting furnace for melting to obtain alloy sheets with a thickness of 0.2mm-0.3mm; Hydrogen breaking and powder making: The alloy flakes are made into coarse powder by hydrogen breaking process, and the coarse powder is fed into the tank through the feed port. At this time, the partition is rotated to make the through hole and the blanking port misaligned; then the feed port is closed, the stirring shaft is rotated by the driving motor, and the inflation mechanism is started to inflate the stirring shaft, wherein the stirring time is 30 minutes; Molding: After the mixing is completed, the partition is rotated to make the through hole correspond to the drop opening to carry out the powder distribution work, so that the powder falls into the vibration chamber, and the pneumatic vibrator is used to break up the powder in the vibration chamber and drop it on the screen. At this time, the drive mechanism is started to drive the reciprocating screw to rotate, so that the tank body slides back and forth in the limit slide groove, so that the powder is spread layer by layer in the mold cavity; a one-time molding mold is used here to press the powder into a density of 4.4g / cm under the magnetic field orientation. 3 Greenware; Sintering: The green body is sent into a vacuum sintering furnace in a low oxygen environment for sintering and tempering treatment.

8. The method for preparing the high-efficiency sintered NdFeB magnet according to claim 7, characterized in that: During the forming process, the tank body slides back and forth along the limiting slide groove, and the tank body drives the connecting rod to move synchronously, thereby driving the gear to move along the rack to rotate the gear, thereby rotating the cam. The rotation of the cam can cause the screen to move back and forth up and down to generate vibration force on the screen.

9. The method for preparing the high-efficiency sintered NdFeB magnet according to claim 8, characterized in that: During the powder distribution process, the tank body moves in sections, with the speed of the first section being 30 mm / s, the second section being 50 mm / s, and the third section being 70 mm / s.

10. The method for preparing the high-efficiency sintered NdFeB magnet according to claim 9, characterized in that: Before powder distribution, the bottom plate is set close to the top wall of the mold. During the powder distribution process, the bottom plate is driven to move downward, and the bottom plate descends at a speed of 5 mm / s.

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