A method for preparing a bonded magnet with radial gradient magnetic powder distribution through centrifugal assisted solidification

Abstract

The present invention discloses a device and method for radial gradient magnetic powder distribution of bonded magnets with centrifugal assisted curing, comprising a centrifugal barrel unit as a slurry container, the centrifugal barrel unit comprising a centrifugal barrel body, a first end cover, and a second end cover; a transmission system is implemented in a manner of regulating the rotational speed of the centrifugal barrel unit; a heating curing device surrounds the outer ring of the centrifugal barrel unit; by optimizing the centrifugal distribution curing device and process parameters, integrated molding of magnetic powder gradient distribution and epoxy resin curing is achieved without the need for segmentation or secondary processing, thereby improving efficiency; the prepared magnet has strong interface bonding force and high density, meeting special magnetic performance requirements; the centrifugal barrel is flexibly designed to adapt to different removal requirements; with the assistance of centrifugal rotation, magnetic powder is gathered in the outer ring, achieving a higher magnetic induction intensity of the outer ring than that of the inner ring; this magnetic powder distribution structure enables the magnet to exhibit higher magnetic induction intensity under limited volume and magnetic powder content, meeting various working conditions.

Description

Technical Field

[0001] The invention relates to a method for preparing a bonded magnet, in particular to a method for preparing a bonded magnet with radial gradient magnetic powder distribution through centrifugal auxiliary solidification. Background Art

[0002] Bonded magnets are functional materials composed of magnetic powder and a polymer binder. They combine adjustable magnetic properties with flexible molding characteristics and are widely used in precision electromagnetic devices such as motors, sensors, and permanent magnet couplers. Traditional bonded magnet preparation processes primarily include compression molding and injection molding. These methods uniformly mix the magnetic powder and binder and directly solidify them to form a magnet with a uniform distribution of magnetic powder inside. Currently, with the increasing efficiency of motors and the reduction in sensor size, a single uniform magnetic property is no longer sufficient for specific applications. For example, if the motor rotor magnetic ring can form a radial magnetic performance gradient with a high outer edge and a low inner edge, the distribution of the air gap magnetic field can be optimized and eddy current losses can be reduced. Similarly, if the sensor core has a magnetic permeability gradient, the signal sensitivity and linearity will be significantly improved. In the existing technology, there are two main methods to achieve magnet gradient: the first is the segmented molding process, which is to fill materials with different magnetic powder ratios layer by layer and solidify them. However, this method has problems such as weak interlayer interface bonding, complex process and low material utilization rate; the second is the post-processing method, which is to locally modify the uniform magnet through mechanical processing or laser processing. This method will destroy the structural integrity of the magnet and increase production costs.

[0003] Upon inquiry, patent CN115888940B mentions a method for regulating the residual magnetic strength between different positions of a bonded magnet, that is, by screening different magnetic powder particle sizes, making the magnetic powder particle sizes different at different parts of the magnetic ring, thereby achieving the purpose of regulating its magnetic field strength. Patent CN113764148B mentions a method of regulating the magnetic field strength at different positions of a bonded magnet by stacking and forming magnetic powder contents with different ratios / densities. Patent CN118299144A mentions that the local strengthening effect of the annular magnet is achieved by pressing the inner and outer layers of the bonded magnetic ring with different types of magnets. The above molding methods cannot avoid the limitations of segmented molding or local modification, that is, weak interface bonding, complex process and high production cost.

[0004] In view of this, a device and method for radial gradient magnetic powder distribution of centrifugal assisted solidification bonded magnets are proposed, focusing on solving the molding problem of bonded magnets with radial magnetic powder gradient distribution. Summary of the Invention

[0005] In order to solve the shortcomings of the above technologies, the present invention provides a device and method for radial gradient magnetic powder distribution of a bonded magnet with centrifugal assisted solidification.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a device and method for radial gradient magnetic powder distribution of a centrifugal assisted solidified bonded magnet, comprising:

[0007] The centrifugal barrel unit, serving as a slurry container, is subjected to centrifugal force to cause the magnetic powder to migrate radially in the binder. The centrifugal barrel unit includes a centrifugal barrel body and a first end cover and a second end cover respectively located at two open sides thereof. The first end cover and the second end cover are both provided with a rotating shaft at their axis.

[0008] A transmission system is connected to the centrifugal bucket unit and drives it to rotate, and the transmission system is also implemented in a manner of regulating the rotation speed of the centrifugal bucket unit;

[0009] The heating and curing device surrounds the outer ring of the centrifugal barrel unit, and a matching gap is formed between the heating and curing device and the centrifugal barrel body.

[0010] Furthermore, the centrifugal barrel body is of an integrated or split type.

[0011] Furthermore, the inner side surfaces of the first end cover and the second end cover are both formed with a stepped inner layer with a smaller diameter, the maximum diameter of the inner layer matches the maximum diameter of the centrifugal barrel body, and the outer ring part of the inner layer of each of the first end cover and the second end cover is provided with a number of corresponding groups of threaded holes.

[0012] Furthermore, the threaded holes in the corresponding groups on the first end cover and the second end cover are fastened with connecting rods, so that the connecting rods are evenly distributed in the circumferential direction of the outer periphery of the centrifugal barrel.

[0013] Furthermore, the first end cover is provided with an air port and a material injection port connected to the inner cavity of the centrifugal barrel body, the air port is detachably connected to an air port cover, and the material injection port is detachably connected to a material injection port cover.

[0014] Furthermore, bearings are provided on both sides of the rotating shaft and are rotatably connected to the fastening sleeves through the bearings.

[0015] Furthermore, the transmission system includes a servo motor, which is transmission-connected to one side of the rotating shaft via a coupling.

[0016] A method for a radial gradient magnetic powder distribution device for a centrifugal assisted solidification bonded magnet comprises the following steps:

[0017] S1. Premixing stage, the magnetic powder, silane coupling agent and binder are mixed and stirred to form a uniform slurry, the binder being an epoxy resin and a curing agent system;

[0018] S2 assembly stage, first select the split centrifugal barrel or the integrated centrifugal barrel according to the magnet type, then spray the release agent on the inner wall of the centrifugal barrel, and then complete the rigid connection of the centrifugal barrel unit, and finally close the air port and the injection port after the injection;

[0019] S3. Centrifugal gradient forming stage, including:

[0020] In the first sub-stage, the time is 0-5 minutes, the servo motor is started to drive the rotation speed of the centrifugal bucket unit from 0 to 1500-1800 rpm, so that the magnetic powder migrates to the outer edge for enrichment;

[0021] The second sub-stage lasts for 5-15 minutes, during which the servo motor reduces the rotation speed of the centrifugal barrel unit to 800-1000 rpm in a step-by-step manner to promote the penetration of the resin into the gaps between the magnetic powders.

[0022] The third sub-stage lasts for 15 minutes until the curing is completed. The rotation speed of the centrifugal barrel unit is stabilized at 500 rpm by the servo motor to maintain the distribution gradient structure of the magnetic powder previously generated.

[0023] S4. Curing stage, including,

[0024] Pre-curing: increasing the viscosity of the slurry at the pre-curing temperature of the epoxy resin;

[0025] Main curing: at the curing temperature of epoxy resin, the magnetic powder surface modified by silane coupling agent undergoes cross-linking reaction with epoxy resin to maintain solid state;

[0026] Post-curing, at a temperature lower than the curing temperature of the epoxy resin, to release the stress of the molded bonded magnet;

[0027] S5. Demolding stage: After cooling, disassemble the centrifugal barrel unit to remove the bonded magnet.

[0028] Furthermore, the particle size of the magnetic powder is 1-10 μm, and the added content is 70-85 wt%;

[0029] The silane coupling agent is KH-550, and the added content is 0.5-2wt%.

[0030] Furthermore, the mixing and stirring speed in the premixing stage is 200-400 rpm, and the mixing and stirring time is 30-60 minutes.

[0031] The centrifugal-assisted curing radial gradient magnetic powder distribution device and method for bonded magnets achieves an integrated molding process of magnetic powder gradient distribution and epoxy resin curing by synergistically optimizing the centrifugal-based distribution curing device and process parameters. This process does not require gradient segmented molding or secondary processing molding, greatly improving the efficiency of the process flow. The resulting magnet has strong interfacial bonding, high material density, and its magnetic properties can meet the device's special requirements for spatial magnetic fields. The centrifugal barrel's dimensional design can flexibly adopt a split or integrated form to adapt to the removal of finished products in different scenarios. In terms of process methods, centrifugal rotation is used to assist, causing the magnetic powder to gather in the outer ring of the magnet during the molding process, thereby achieving the effect of higher magnetic induction intensity in the outer ring than in the inner ring. This optimized magnetic powder distribution structure enables the magnet to exhibit higher magnetic induction intensity within a limited magnet volume and magnetic powder content, meeting the requirements of use under various working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural setting diagram of the present invention.

[0033] Figure 2 A diagram showing the structure of the centrifugal bucket unit.

[0034] Figure 3 This is a comparison chart of the integrated and split centrifugal barrel types.

[0035] Figure: 1, centrifugal barrel unit; 10, centrifugal barrel body; 11, first end cap; 110, inner layer; 12, second end cap; 13, connecting rod; 14, threaded hole; 15, air port; 16, air port cover; 17, injection port; 18, injection port cover; 19, rotating shaft

[0036] 2. Transmission system; 20. Servo motor; 21. Coupling; 22. Bearing; 23. Fastening sleeve;

[0037] 3. Heat the curing device. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] This embodiment is about the radial gradient magnetic powder distribution device and method of bonded magnets with centrifugal assisted curing. It innovates on the structure of the centrifugal barrel and adapts to the scenario of taking out the finished product through different forms of centrifugal barrels. On this basis, based on the inherent density difference between magnetic powder and binder, combined with the viscosity change during the binder curing process, the rotation condition is used to combine the dynamic regulation of centrifugal force with the resin curing process. Through the coordinated control of staged rotation speed and temperature, the directional migration and gradient curing of magnetic powder are realized, and the radial gradient distribution effect of the formed bonded magnet is achieved.

[0041] The centrifugal assisted solidification bonded magnet radial gradient magnetic powder distribution device includes a centrifugal barrel unit 1, which serves as a slurry container and is subjected to centrifugal force to cause the magnetic powder to migrate radially in the binder, such as Figure 2 As shown, the centrifugal bucket unit 1 includes a centrifugal bucket body 10 and a first end cover 11 and a second end cover 12 respectively located at the openings on both sides thereof. A rotating shaft 19 is provided at the axis of the first end cover 11 and the second end cover 12 .

[0042] Preferably, the centrifugal barrel 10 adopts a cylindrical structure, and the material can be selected from metal materials such as stainless steel, and can also be selected from polymer composite materials such as carbon fiber composite materials; compared with traditional general-purpose containers, this embodiment optimizes the structure of the magnet gradient forming requirements, such as Figure 3 As shown, the centrifugal barrel body 10 includes an integrated or split type. The integrated centrifugal barrel body 10, such as a carbon fiber composite material, can be directly used as a rotor sleeve to avoid damage to the gradient structure caused by secondary processing; the split centrifugal barrel body 10, such as Figure 3 The three-petal structure shown is convenient for demoulding and is suitable for scenarios where finished products need to be removed, such as magnetic rings.

[0043] like Figure 2 As shown, the first end cover 11 and the second end cover 12 are both solid flange structures. The inner side surfaces of the first end cover 11 and the second end cover 12 are formed with a circle of stepped inner layer 11 with a smaller diameter. The maximum diameter of the inner layer 11 matches the maximum diameter of the centrifugal barrel body 10, thereby enhancing the sealing effect of the connection position. The outer circle part of the inner layer 11 of the first end cover 11 and the second end cover 12 is provided with a plurality of corresponding groups of threaded holes 14, which facilitates the positioning and rigid connection of the first end cover 11 and the second end cover 12.

[0044] Furthermore, the corresponding groups of threaded holes 14 on the first end cover 11 and the second end cover 12 are fastened together with a connecting rod 13, and several of the connecting rods 13 are evenly distributed circumferentially around the periphery of the centrifugal barrel body 10, so that a ring-shaped frame-type rigid connection is formed around the periphery of the centrifugal barrel body 10, the structural strength is guaranteed, and the non-invasive design avoids occupying the internal space of the barrel body, ensuring that there is no structural interference when the slurry is filled, and is convenient for disassembly and maintenance. It is needless to say that external threads that adapt to the threaded holes 14 are provided at both ends of the connecting rod 13.

[0045] The first end cover 11 is provided with an air port 15 and an injection port 17 which are connected to the inner cavity of the centrifugal barrel body 10 to ensure that the slurry is filled evenly and without interference from bubbles. The number of the air ports 15 and the injection ports 17 is not limited in this embodiment. It should be noted that in order to maintain the dynamic balance of the centrifuge in actual processing, auxiliary holes of the same specifications can be added at the central symmetrical positions of the air port 15 and the injection port 17. The air port cover 16 is detachably connected to the air port 15, and the injection port cover 18 is detachably connected to the injection port 17.

[0046] The rotating shafts 19 on both sides are provided with bearings 22 and are rotatably connected to the fastening sleeves 23 via the bearings 22 .

[0047] like Figure 1 As shown, the transmission system 2 is connected to the centrifugal barrel unit 1 and drives it to rotate. The transmission system 2 is also implemented in a manner of regulating the rotational speed of the centrifugal barrel unit 1. The transmission system 2 includes a servo motor 20, which is connected to the rotating shaft 19 on one side through a coupling 21, thereby forming a tight transmission connection relationship. Under the drive of the servo motor 20, the centrifugal barrel body 10 reaches a specified rotational speed. The servo motor 20 selected in this embodiment supports stepless speed regulation and multi-stage speed gradient programming, thereby realizing the segmented increase or decrease in the rotational speed of the centrifugal barrel body 10, which can be customized as required.

[0048] The heating and curing device 3 surrounds the outer ring of the centrifugal barrel unit 1. The heating and curing device 3 provides a curing temperature field for the magnetic powder slurry inside the centrifugal barrel body 10 through external heating. A matching gap is formed between the heating and curing device 3 and the centrifugal barrel body 10. It should be noted that the heating mechanism adopted by the heating and curing device 3 is a closed cavity, which adopts blast heating, and is customized to support multi-stage temperature control programming and heating rate control in temperature control.

[0049] The method of the centrifugal assisted solidification bonded magnet radial gradient magnetic powder distribution device of this embodiment is characterized by comprising the following steps:

[0050] S1. Premixing stage, the magnetic powder, silane coupling agent and binder are mixed and stirred to form a uniform slurry, the binder being an epoxy resin and a curing agent system;

[0051] Preferably, the magnetic powder has a particle size of 1-10 μm and an addition content of 70-85 wt%. Magnetic powder with a fine particle size is more likely to migrate in the mixed slurry due to centrifugal rotation, while preventing the magnetic powder from agglomerating in the epoxy resin. The silane coupling agent is KH-550, and the addition content is 0.5-2 wt%. The silane coupling agent is used to improve interfacial bonding, specifically chemically modifying the surface of the magnetic powder to increase the bonding strength between the magnetic powder and the epoxy resin, effectively inhibiting the interfacial delamination of the magnetic powder under high centrifugal force.

[0052] The mixing speed in the premixing stage is 200-400 rpm, and the mixing time is 30-60 minutes to stabilize the viscosity of the slurry.

[0053] S2 assembly stage, first select the split centrifugal barrel 10 or the integrated centrifugal barrel 10 according to the type of magnet, then spray the release agent on the inner wall of the centrifugal barrel 10, and then complete the rigid connection of the centrifugal barrel unit 1 again, and finally close the gas port 15 and the injection port 17 after injection;

[0054] It should be noted that if a split centrifugal barrel 10 is used, it needs to be assembled and spliced ​​in advance.

[0055] S3. Centrifugal gradient forming stage, including:

[0056] In the first sub-stage, which lasts for 0-5 minutes, the servo motor 20 is started to drive the rotation speed of the centrifugal bucket unit 1 from 0 to 1500-1800 rpm. The strong centrifugal force generated at this speed causes the magnetic powder to migrate to the outer edge and be enriched;

[0057] In the second sub-stage, which lasts for 5-15 minutes, the rotation speed of the centrifugal barrel unit 1 is stepped down to 800-1000 rpm by the servo motor 20 to promote the penetration of the resin into the gaps between the magnetic powders. Specifically, this rotation speed can slow down the sedimentation rate and promote the penetration of the epoxy resin into the gaps between the magnetic powders, thereby avoiding the phenomenon of reduced adhesion or even shedding caused by insufficient epoxy resin content between the magnetic powders.

[0058] In the third sub-stage, the time is 15 minutes until the curing is completed. The rotation speed of the centrifugal barrel unit 1 is stabilized at 500 rpm by the servo motor 20 to maintain the distribution gradient structure of the magnetic powder previously produced. Specifically, at this speed, the magnetic powder distribution gradient structure produced in the first two stages can be maintained and the sedimentation phenomenon caused by the secondary flow of the magnetic powder due to gravity can be suppressed.

[0059] S4. Curing stage, including,

[0060] Pre-curing: at the pre-curing temperature of epoxy resin, the viscosity of the slurry is increased, and the migration speed of the magnetic powder is slowed down to facilitate subsequent curing;

[0061] Main curing: at the curing temperature of epoxy resin, the magnetic powder surface modified by silane coupling agent undergoes cross-linking reaction with epoxy resin to maintain solid state;

[0062] Post-curing releases stress in the molded bonded magnet at a temperature lower than the curing temperature of the epoxy resin.

[0063] S5. Demolding stage: After cooling, the centrifugal barrel unit 1 is disassembled to remove the bonded magnet.

[0064] The method of the centrifugal assisted curing bonded magnet radial gradient magnetic powder distribution device disclosed in this embodiment is based on the coordinated optimization of the device and process parameters, realizing the integrated molding of magnetic powder gradient distribution and epoxy resin curing, without the need for gradient segmented molding or secondary processing molding, and the process flow is highly efficient; the magnet obtained has strong interface bonding force, high material density, and magnetic properties that can meet the device's special requirements for spatial magnetic fields.

[0065] Example 2

[0066] This embodiment is based on the embodiment 1 and takes the preparation of a NdFeB magnetic ring with a radial distribution gradient of magnetic powder as an example.

[0067] First, assemble the split centrifugal barrel body 10 made of stainless steel, and then install the centrifugal barrel unit 1 as a whole; after cleaning the inner wall of the centrifugal barrel body 10, evenly apply a release agent, and then preheat to 50°C.

[0068] Next, 80% NdFeB magnetic powder, 9% epoxy resin, 9% curing agent, and 2% silane coupling agent were added to an external mixer. The mixer was first mixed at a low speed of 200 rpm for 5 minutes to allow the materials to be wetted. The mixer was then increased to a high speed of 400 rpm for 15 minutes and a vacuum pump was used to remove bubbles. The mixed slurry was then transferred to the barrel of a high-pressure injection machine and injected into the centrifugal barrel 10 from the injection port. After the centrifugal barrel 10 was filled, the injection port 17 was closed and the residual gas was discharged.

[0069] Again, centrifuge:

[0070] In the first 3 minutes, the rotation speed of the centrifugal barrel 10 is linearly increased from 0 to 1500 rpm, and the centrifugal acceleration is used to drive the magnetic powder to migrate to the outer edge to form a magnetic powder enrichment layer, and the operation is maintained at 1500 rpm for 5 minutes; then the speed is gradually reduced to stabilize at 800 rpm after 10 minutes; after 15 minutes, the speed is reduced to 500 rpm, and the heating curing device is started at the same time to heat the centrifugal barrel 10.

[0071] It should be noted that the curing process is divided into pre-curing (keeping at 60°C for 30 minutes), main curing (keeping at 100–120°C for 1 hour) and post-curing (keeping at 80°C for 30 minutes).

[0072] Finally, the centrifugal barrel body 10 is removed after cooling, and the bonded magnet is taken out of the centrifugal barrel body 10, and then a magnetic ring of corresponding size can be obtained through mechanical processing.

[0073] Thus, a bonded magnetic ring is obtained in which the magnetic powder density increases radially from the inside to the outside.

[0074] Example 3

[0075] This embodiment is based on the embodiment 1 and takes the preparation of a high-speed motor composite rotor with a specific volume as an example. It should be noted that the specific volume is not an unclear concept, but means production according to actual needs in existing production and manufacturing.

[0076] First, the one-piece centrifugal barrel body 10 made of carbon fiber material is installed. The thin-walled centrifugal barrel body 10 made of carbon fiber material can be directly used as a rotor sleeve in the subsequent process without removing the rotor formed therein. After the centrifugal barrel unit 1 is installed, it is connected to the transmission system 2, and then the inner wall of the centrifugal barrel body 10 is cleaned and evenly coated with a silane coupling agent to enhance the bonding force between the formed composite rotor and the centrifugal barrel body 10 used as a sleeve. After completion, it is preheated to 50°C. It should be noted that since the centrifugal barrel body 10 in this embodiment is directly used as a rotor sleeve, this embodiment does not require the inner wall of the centrifugal barrel body 10 to be coated with a release agent, but the above-mentioned silane coupling agent.

[0077] Next, 50% NbFeB magnetic powder, 24% epoxy resin, 24% curing agent, and 2% silane coupling agent were stirred in an external mixer at a speed of 500 rpm for 10 minutes to fully mix them, and an external vacuum pump was used to remove bubbles.

[0078] Next, the carbon fiber tow is spirally wrapped on the surface of the metal shaft through a winding system, and a carbon fiber multilayer prepreg structure of corresponding size is made according to the required size. The prepared carbon fiber multilayer prepreg structure is then placed in an integrated carbon fiber thin-walled centrifugal barrel 10, and a slurry mixed with magnetic powder and epoxy resin is injected into the injection port 17.

[0079] Centrifugal treatment after slurry injection:

[0080] In the first 3 minutes, the rotation speed of the centrifugal barrel 10 is linearly increased from 0 to 1800 rpm. The centrifugal acceleration is used to drive the magnetic powder to migrate to the outer edge to form a magnetic powder enrichment layer. The rotation speed is maintained at 1800 rpm for 5 minutes, and then the speed is gradually reduced to stabilize at 1000 rpm after 10 minutes. After 15 minutes, the rotation speed is reduced to 500 rpm. At the same time, the curing program is started. The centrifugal barrel device is heated by the heating curing device 3. The curing process is divided into pre-curing (keeping at 60°C for 30 minutes), main curing (keeping at 100-120°C for 1 hour) and post-curing (keeping at 80°C for 30 minutes).

[0081] Finally, after the centrifugal barrel body 10 is cooled, the centrifugal barrel body 10 is disassembled to form a high-speed motor composite rotor with an outer layer having high magnetic powder content, an inner layer having high fiber strength and an integrated carbon fiber rotor sleeve.

[0082] The present application discloses a device and method for radial gradient magnetic powder distribution of bonded magnets with centrifugal assisted curing. By synergistically optimizing the centrifugal distribution curing device and process parameters, an integrated molding process of magnetic powder gradient distribution and epoxy resin curing is achieved. This process does not require gradient segmented molding or secondary processing molding, greatly improving the efficiency of the process flow. The resulting magnet has strong interface bonding force and high material density, and its magnetic properties can meet the device's special requirements for spatial magnetic fields. In terms of the dimensional design of the centrifugal barrel, it can be flexibly adopted in a split or integrated form to adapt to the removal of finished products in different scenarios. In terms of process methods, centrifugal rotation is used to assist in causing the magnetic powder to gather in the outer ring of the magnet during the molding process, thereby achieving the effect of the outer ring's magnetic induction intensity being higher than the inner ring. This optimized magnetic powder distribution structure enables the magnet to exhibit higher magnetic induction intensity under limited magnet volume and magnetic powder content, meeting the use requirements under various working conditions.

[0083] The above embodiments are not limitations of the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by technicians in this technical field within the scope of the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A method for preparing a bonded magnet with radial gradient magnetic powder distribution through centrifugal assisted solidification, characterized in that: The devices used include: A centrifugal barrel unit (1) serves as a slurry container and is subjected to centrifugal force to cause magnetic powder to migrate radially in a binder. The centrifugal barrel unit (1) comprises a centrifugal barrel body (10) and a first end cover (11) and a second end cover (12) respectively located at two open ends thereof. A rotating shaft (19) is provided at the axis of each of the first end cover (11) and the second end cover (12). The first end cover (11) is provided with an air port (15) and a material injection port (17) communicating with the inner cavity of the centrifugal barrel body (10). The air port (15) is detachably connected to an air port cover (16), and the material injection port (17) is detachably connected to an injection port cover (18). A transmission system (2) is connected to the centrifugal barrel unit (1) and drives the centrifugal barrel unit (1) to rotate. The transmission system (2) is also implemented in a manner of regulating the rotation speed of the centrifugal barrel unit (1). The transmission system (2) includes a servo motor (20), and the servo motor (20) is connected to one side of the rotating shaft (19) through a coupling (21). A heating and curing device (3) surrounds the outer ring of the centrifugal barrel unit (1), and a matching gap is formed between the heating and curing device (3) and the centrifugal barrel body (10); The preparation method comprises the following steps: S1. Premixing stage, the magnetic powder, silane coupling agent and binder are mixed and stirred to form a uniform slurry, the binder being an epoxy resin and a curing agent system; S2. In the assembly stage, first, a split centrifugal barrel body (10) or an integrated centrifugal barrel body (10) is selected according to the type of magnet, and then a mold release agent is sprayed on the inner wall of the centrifugal barrel body (10), and the rigid connection of the centrifugal barrel unit (1) is completed again. Finally, after the injection, the air port (15) and the injection port (17) are closed; S3. Centrifugal gradient forming stage, including: In the first sub-stage, the duration is 0-5 minutes, the servo motor (20) is started to drive the rotation speed of the centrifugal bucket unit (1) from 0 to 1500-1800 rpm, so that the magnetic powder migrates to the outer edge for enrichment; In the second sub-stage, which lasts for 5-15 minutes, the rotation speed of the centrifugal barrel unit (1) is reduced stepwise to 800-1000 rpm by the servo motor (20) to promote the penetration of the resin into the gaps between the magnetic powders; The third sub-stage lasts for 15 minutes until the curing is completed, and the rotation speed of the centrifugal barrel unit (1) is stabilized at 500 rpm by the servo motor (20) to maintain the distribution gradient structure of the magnetic powder previously generated; S4. Curing stage, including, Pre-curing: increasing the viscosity of the slurry at the pre-curing temperature of the epoxy resin; Main curing: at the curing temperature of epoxy resin, the magnetic powder surface modified by silane coupling agent undergoes cross-linking reaction with epoxy resin to maintain solid state; Post-curing, at a temperature lower than the curing temperature of the epoxy resin, to release the stress of the molded bonded magnet; S5. Demolding stage: After cooling, disassemble the centrifugal barrel unit (1) to remove the bonded magnet.

2. The method for preparing a centrifugal-assisted solidified radially gradient magnetic powder distribution bonded magnet according to claim 1, characterized in that: The centrifugal barrel (10) is of an integrated or split type.

3. The method for preparing a centrifugally assisted solidified radially gradient magnetic powder distribution bonded magnet according to claim 1, characterized in that: The inner side surfaces of the first end cover (11) and the second end cover (12) are each formed with a stepped inner layer (11) having a smaller diameter. The maximum diameter of the inner layer (11) matches the maximum diameter of the centrifugal barrel (10). The outer ring portion of the inner layer (11) of each of the first end cover (11) and the second end cover (12) is provided with a plurality of corresponding threaded holes (14) in groups.

4. The method for preparing a centrifugally assisted solidified radially gradient magnetic powder distribution bonded magnet according to claim 1, characterized in that: The corresponding groups of threaded holes (14) on the first end cover (11) and the second end cover (12) are fastened with connecting rods (13) together, and a plurality of the connecting rods (13) are evenly distributed around the periphery of the centrifugal barrel (10).

5. The method for preparing a centrifugally assisted solidified radially gradient magnetic powder distribution bonded magnet according to claim 1, characterized in that: The rotating shafts (19) on both sides are provided with bearings (22) and are rotatably connected to the fastening sleeves (23) via the bearings (22).

6. The method for preparing a centrifugal-assisted solidified radially gradient magnetic powder distribution bonded magnet according to claim 1, characterized in that: The particle size of the magnetic powder is 1-10 μm, and the added content is 70-85 wt%; The silane coupling agent is KH-550, and the added content is 0.5-2wt%.

7. The method for preparing a centrifugal-assisted solidified radially gradient magnetic powder distribution bonded magnet according to claim 1, characterized in that: The mixing and stirring speed in the premixing stage is 200-400 rpm, and the mixing and stirring time is 30-60 minutes.

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