A device and method for improving the coercive force of annular NdFeB magnets

Abstract

The present invention belongs to the technical field of NdFeB magnet processing, and mainly relates to a device and method for improving the coercive force of an annular NdFeB magnet. A layer of heavy rare earth coating is sprayed on the inner and outer surfaces of the annular NdFeB magnet by a lifting device, and then the annular NdFeB magnet sprayed with the heavy rare earth coating is subjected to diffusion aging treatment to improve the coercive force of the annular NdFeB magnet. The present invention uses heavy rare earth slurry as a diffusion source, and combines with spraying technology to quickly and evenly cover the inner and outer surfaces of the annular NdFeB magnet with a layer of heavy rare earth coating, and the coercive force of the annular NdFeB magnet is greatly improved after heat treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of NdFeB magnet processing, and mainly relates to a device and a method for improving the coercive force of an annular NdFeB magnet. Background Art

[0002] Since its appearance in 1983, NdFeB magnets have been widely used in the fields of computers, automobiles, medical treatment and wind power generation. Ring NdFeB magnets have a high application in the field of motors due to their special shape and orientation direction and can achieve better motor performance. During the high-speed rotation of the motor, heat will be generated, causing the magnetism of the NdFeB magnet to continuously weaken, affecting the performance of the motor. Therefore, in order to avoid this situation, the coercive force of the NdFeB magnet used in the motor must be increased.

[0003] NdFeB permanent magnet material is a permanent magnet material based on the intermetallic compound Nd2Fe14B. By adding dysprosium, terbium or their alloys at the boundary of Nd2Fe14B phase to improve the crystalline magnetic anisotropy of Nd2Fe14B phase, the coercivity of NdFeB magnet can be effectively improved. Based on this theory, the grain boundary diffusion technology developed has been widely used in the production and processing of NdFeB magnets due to its excellent performance improvement advantages and high economic value, and different diffusion methods have evolved. However, due to the special shape of the annular NdFeB magnet, the current diffusion methods cannot perform low-cost and efficient heavy rare earth diffusion on the annular NdFeB magnet to improve its coercivity.

[0004] Baotou Tianhe Magnetic Material Technology Co., Ltd., in a document with publication number CN106782980A, disclosed a method of using a heavy rare earth salt solution as an electroplating solution to electroplate a heavy rare earth coating on the surface of a neodymium iron boron magnet, and then diffusing it at high temperature to enhance the magnetic properties. This method is suitable for coating the surface of neodymium iron boron magnets of any shape, including square neodymium iron boron magnets, tile-shaped, steamed bun-shaped, radial ring-shaped, etc., with a heavy rare earth film layer, and then performing diffusion aging to enhance the coercive force of the neodymium iron boron magnet. This method has high versatility, but this method also has certain defects. On the one hand, the heavy rare earth electroplating solution is easily oxidized, resulting in obstruction of the electroplating process. On the other hand, the presence of pinch points and corner effects during the electroplating process will also affect the uniformity of the heavy rare earth film layer. Summary of the invention

[0005] In order to solve the diffusion treatment of annular NdFeB magnets, the present invention provides an annular NdFeB magnet coercivity enhancement device and enhancement method, which can homogenize, stabilize and mass-produce annular NdFeB magnets.

[0006] To achieve the above object, the present invention is implemented by the following technical solutions:

[0007] The present invention provides a ring-shaped NdFeB magnet coercive force enhancement device, comprising a sealed chamber 2, the special feature of which is that:

[0008] A plurality of fixed support frames 4 are installed in the sealed chamber 2, each of which is provided with a roller 5 with a retractable component 7, the retractable component 7 is located on the side wall of the roller 5 and switches between a contracted state and an extended state, and a first spray gun 8 is arranged at the end of the roller 5; each of the fixed support frames 4 is also provided with a slide rail 6, the slide rail 6 is provided with a support groove 9 which reciprocates along the slide rail 6; the second spray gun 10 and the hot air drying spray gun 12 are arranged on one side of the roller 5.

[0009] Furthermore, the lifting device also includes a pressure stirring barrel 1, and the first spray gun 8 and the second spray gun 10 are both air pressure atomizing spray guns. The heavy rare earth slurry in the pressure stirring barrel 1 is atomized by air pressure and then sprayed out. The spraying direction of the first spray gun 8 is perpendicular to the spray gun direction and can spray all around at the same time. The spraying direction of the second spray gun 10 is parallel to the spray gun direction. One end of the first spray gun 8 and one end of the second spray gun 10 are respectively connected to the pressure stirring barrel 1 through pipes, and the other end of the first spray gun 8 and the other end of the second spray gun 10 are respectively connected to their respective nozzles. The second spray gun 10 and the hot air drying spray gun 12 are located directly above the roller 5 and can move back and forth in a plane parallel to the roller 5.

[0010] Furthermore, a fixed base 3 is provided in the sealing chamber 2, and the bottom ends of a plurality of fixed support frames 4 are all mounted on the fixed base 3, and the plurality of fixed support frames 4 are arranged parallel to each other, and the spacing between the plurality of fixed support frames can be adjusted.

[0011] Furthermore, the lifting device is also provided with a motor, and each roller 5 is controlled by the motor to rotate, and the slide rail 6 can also be controlled by the motor to reciprocate up and down along the fixed support frame 4. Each roller 5 is vertically fixed to the side wall of the corresponding fixed support frame 4, and multiple rollers 5 are arranged parallel to each other.

[0012] Furthermore, the support groove 9 is configured to be V-shaped or corrugated or have protrusions on the surface, and the support groove 9 is located directly below the roller 5 .

[0013] The present invention provides a method for improving the coercive force of an annular NdFeB magnet, which is characterized by comprising the following steps:

[0014] a. Preparation of heavy rare earth slurry: heavy rare earth powder R, organic binder and organic solvent are mixed to prepare heavy rare earth slurry;

[0015] b. Installation of annular NdFeB magnets: multiple annular NdFeB magnets to be sprayed are installed on a rotating mechanism that can control the simultaneous rotation of multiple annular NdFeB magnets. Multiple annular NdFeB magnets are on the same plane, parallel to each other, and have a distance between each other.

[0016] c. Preparation of heavy rare earth coating on the outer surface of annular NdFeB magnet:

[0017] A spray gun for spraying the outer surface of the annular NdFeB magnet is arranged on one side of the plane where the multiple annular NdFeB magnets are located. When the multiple annular NdFeB magnets rotate, the spray gun sprays the outer surface of the annular NdFeB magnet. After the spraying is completed, the annular NdFeB magnet is dried with hot air so that the heavy rare earth slurry sprayed on the outer surface of the annular NdFeB magnet is solidified to form a layer of heavy rare earth coating;

[0018] d. Preparation of heavy rare earth coating on the inner surface of annular NdFeB magnet:

[0019] A spray gun for spraying the inner surface of the annular NdFeB magnet is arranged in the axial direction of the multiple annular NdFeB magnets, the multiple annular NdFeB magnets are controlled to be separated from the rotating mechanism, and then the multiple annular NdFeB magnets are controlled to move horizontally as a whole in the direction of the spray gun for spraying the inner surface of the annular NdFeB magnet, and the multiple annular NdFeB magnets pass through the spray gun in sequence, and the heavy rare earth slurry is sprayed on the inner surface of each annular NdFeB magnet, and the annular NdFeB magnet after spraying is removed and placed in an oven for drying, so that the heavy rare earth slurry on the inner surface of the annular NdFeB magnet is solidified to form a heavy rare earth coating;

[0020] e. Diffusion and aging treatment: After that, the annular NdFeB magnet with heavy rare earth coating sprayed on the inner and outer surfaces is subjected to diffusion and aging treatment under vacuum or inert gas protection to improve the coercive force of the NdFeB magnet.

[0021] Furthermore, the component of the heavy rare earth powder R in step a is metal terbium or metal dysprosium, and the heavy rare earth powder R is in the state of pure metal powder, compound powder or alloy powder; the organic adhesive is a resin-type adhesive or a rubber-type adhesive, and the organic solvent is a ketone, benzene or ester solvent.

[0022] Furthermore, the rotating mechanism in step b includes a roller 5, a retractable component 7 located on the side wall of the roller 5, and a plurality of annular NdFeB magnets are sleeved on the retractable component 7, and the retractable component 7 is supported so that the plurality of annular NdFeB magnets are supported on the retractable component 7;

[0023] The spray gun used to spray the outer surface of the annular NdFeB magnet in step c is a second spray gun, and the second spray gun forms a distance with the surface of the annular NdFeB magnet to be sprayed;

[0024] In step d, the multiple annular NdFeB magnets are separated from the support of the telescopic component 7 by contracting the telescopic component 7 .

[0025] Furthermore, the spray gun used to spray the inner surface of the annular NdFeB magnet in step d is a first spray gun, and a plurality of annular NdFeB magnets are controlled to move toward the position of the first spray gun by a support mechanism. The support mechanism includes a support frame 4, a slide rail 6 moving up and down along the support frame, and a support groove 9 for supporting a plurality of annular NdFeB magnets. When the plurality of annular NdFeB magnets detach from the roller 5, the support groove 9 drives the plurality of annular NdFeB magnets to move toward the first spray gun under the action of the slide rail 6; the thickness of the heavy rare earth coating on the inner surface of the NdFeB magnet is greater than or equal to the thickness of the heavy rare earth layer on the outer surface.

[0026] Furthermore, the temperature of the diffusion treatment in step f is 850°C-950°C, the diffusion time is 4-72h, the aging temperature of the aging treatment is 450-650°C, and the aging time is 3-15h.

[0027] Compared with the prior art, the present invention is beneficial in that:

[0028] By using the coercive force enhancing device and the enhancing method of the present invention, a layer of heavy rare earth slurry can be quickly coated on the inner and outer surfaces of the annular NdFeB magnet, and the coercive force of the annular NdFeB magnet can be greatly enhanced after diffusion, providing a new method for the diffusion of annular NdFeB magnets. In addition, compared with the existing methods of electrophoresis, electroplating, etc. for diffusing annular NdFeB magnets, the heavy rare earth coating obtained on the outer or inner surface of the annular NdFeB magnet by using the present invention is more uniform, and the film thickness on the outer surface and the outer surface is more controllable, and the coercive force of the annular NdFeB magnet after diffusion is more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a side view of the lifting device of the present invention;

[0030] Figure 2 It is a front view of the lifting device of the present invention.

[0031] Marking description: 1. Pressure mixing barrel, 2. Sealing chamber, 3. Fixed base, 4. Fixed support frame, 5. Roller, 6. Slide rail, 7. Retractable component, 7-1. Retractable component in the propped-up state, 7-2. Retractable component in the retracted state, 8. First spray gun, 9. Support groove, 10. Second spray gun, 11. Ring-shaped NdFeB magnet, 12. Hot air drying spray gun. DETAILED DESCRIPTION

[0032] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The explanation of the present invention in the specific implementation manner is not intended to limit the scope of the present invention. The orientation used is for the convenience of describing the present invention, but the installation position of the present invention is not limited thereto.

[0033] Regarding the lifting device used in the present invention, it is installed in the sealed chamber 2, and the spraying work of the annular NdFeB magnet is completed in the sealed chamber 2. A rotating mechanism and a supporting mechanism are arranged in the sealed chamber 2. The rotating mechanism includes a roller 5 and a retractable component 7; the supporting mechanism includes a fixed base 3, a supporting frame 4, a slide rail 6, and a supporting groove 9; the lifting device is also provided with a spraying mechanism, and the spraying mechanism includes a first spray gun 8, a second spray gun 10, and a hot air drying spray gun 12.

[0034] One end of the first spray gun 8 and one end of the second spray gun 10 are connected to the pressure stirring barrel 1 through pipelines. The pressure stirring barrel 1 contains heavy rare earth slurry. The other end of the first spray gun 8 and the other end of the second spray gun 10 are connected to their respective nozzles. The first spray gun and the second spray gun are both pneumatic atomizing spray guns.

[0035] In the present application, the sealed chamber 2 is described according to the orientations of the top, bottom, left and right sides. A fixed base 3 is provided at the bottom end inside the sealed chamber 2, a support frame 4 is provided above the fixed base 3, and a roller 5 is provided at the upper part of the support frame 4. The roller 5 is parallel to the bottom end of the sealed chamber 2, and the roller 5 can rotate on its own.

[0036] A telescopic component 7 is installed on the outer surface of the roller 5, and multiple annular NdFeB magnets are sleeved on the telescopic component 7. The telescopic component 7 is multiple telescopic rods arranged on the roller 5. The roller 5 and the telescopic component 7 are both controlled by a motor. The motor controls the rotation of the roller 5, and the motor controls the contraction and extension of the telescopic component 7. The telescopic component 7 switches between the contraction and extension states. When the telescopic component 7 is extended, the multiple annular NdFeB magnets sleeved on the telescopic component 7 rotate synchronously with the roller 5. When the telescopic component 7 contracts, the inner wall of the multiple annular NdFeB magnets does not contact the telescopic component 7 and is out of the control of the roller 5.

[0037] In this embodiment, only one roller 5 is installed, and three annular NdFeB magnets are placed on one roller 5. According to the spraying requirements, multiple rows of parallel rollers can be set, and multiple annular NdFeB magnets are placed on each roller. The multiple annular NdFeB magnets on the same roller are coaxial. When there are multiple rollers, the number of rollers is not less than 2, and the center distance between the rollers can be adjusted.

[0038] The second spray gun 10 and the hot air drying spray gun 12 are both located above the plane where the three annular NdFeB magnets are located. The second spray gun 10 and the hot air drying spray gun 12 are located directly above the roller 5 and can move back and forth in a plane parallel to the roller 5, and the position of the second spray gun 10 and the hot air drying spray gun 12 directly above the roller 5 is adjustable. When the three annular NdFeB magnets are supported by the retractable component 7, the second spray gun 10 sprays the outer surfaces of the three annular NdFeB magnets when the roller 5 drives the three annular NdFeB magnets to rotate, and the heavy rare earth slurry in the pressure stirring barrel 1 is atomized by air pressure and then sprayed out, and the spraying direction of the second spray gun 10 is parallel to the spray gun direction.

[0039] A slide rail 6 is arranged at the lower part of the support frame 4. The slide rail 6 is controlled by a motor to reciprocate up and down along the fixed support frame 4. A support groove 9 is arranged on the slide rail 6 to reciprocate along the slide rail 6. The support groove 9 is arranged to be V-shaped or corrugated or has protrusions on the surface. The support groove 9 is located directly below the roller 5. The slide rail 6 drives the support groove 9 to move up and down until the support groove 9 can support or detach from the annular NdFeB magnet. After that, the slide rail 6 stops moving, and the support groove 9 starts to slide back and forth along the slide rail 6, that is, it moves below the axial direction of the roller. The support groove is illustrated by a V-shape in this embodiment.

[0040] A first spray gun 8 is disposed at one end of the roller 5 away from the support frame 4. The first spray gun 8 and the central axis of the roller 5 are in the same straight line. The first spray gun 8 is used to spray the inner surface of the annular NdFeB magnet.

[0041] The control slide rail 6 moves upward along the fixed support frame 4 to the bottom of the three annular NdFeB magnets, and the telescopic component 7 contracts. The three annular NdFeB magnets contact the upper surface of the V-shaped support groove 9. At this time, the support groove 9 provides support for the three annular NdFeB magnets, driving the three annular NdFeB magnets to move toward the first spray gun 8. When the three annular NdFeB magnets pass through the first spray gun 8 in turn, the spraying of the inner surfaces of the three annular NdFeB magnets is completed.

[0042] When the lifting device of the present application is used to increase the coercive force of the annular NdFeB magnet, the following steps are performed:

[0043] a. Prepare heavy rare earth slurry by mixing heavy rare earth powder R with organic binder and organic solvent in advance, and place the prepared heavy rare earth slurry in pressure stirring barrel 1 for stirring. Heavy rare earth powder R refers to pure metal powder, compound powder or alloy powder of metal terbium or metal dysprosium; the organic binder is a resin-type binder or a rubber-type binder, and the organic solvent is a ketone, benzene or ester solvent.

[0044] b. Installation of annular NdFeB magnets: put three annular NdFeB magnets on the retractable part 7 of the roller 5, adjust the retractable part 7 to be in a propped-up state, prop up the three annular NdFeB magnets, turn on the roller 5 so that the annular NdFeB magnets and the roller 5 perform coaxial rotation motion;

[0045] c. Preparation of heavy rare earth coating on the outer surface of the annular NdFeB magnet: move the second spray gun 10 and the hot air drying spray gun 12 to the top of the three annular NdFeB magnets 11 to be sprayed, and adjust the distance between the second spray gun 10 and the surface of the annular NdFeB magnet, then open the second spray gun 10 to spray the outer surface of the annular NdFeB magnet, close the second spray gun 10 after spraying, and open the hot air drying spray gun 12 to perform hot air drying on the annular NdFeB magnet, so that the heavy rare earth slurry sprayed on the outer surface of the annular NdFeB magnet is solidified, and finally a layer of heavy rare earth coating is formed on the outer surface of the annular NdFeB magnet;

[0046] d. Preparation of heavy rare earth coating on the inner surface of the annular NdFeB magnet 11: After drying, the roller 5 is closed to stop the self-rotation, and then the slide rail 6 is started to drive the V-shaped support groove 9 to move upward along the fixed support frame 4 until the V-shaped support groove 9 completely supports the three annular NdFeB magnets 11, and the retractable component 7 on the roller 5 is adjusted to be in a contracted state, so that the annular NdFeB magnet is separated from the roller 5; the control motor is turned on to make the V-shaped support groove 9 hold the three annular NdFeB magnets and move toward the first spray gun 8 at the top of the roller, and the first spray gun 8 is turned on at the same time, so that the first spray gun 8 starts to spray heavy rare earth slurry all around, and when passing through the first spray gun 8, a layer of heavy rare earth slurry is sprayed on the inner surface of the annular NdFeB magnet, and the annular NdFeB magnet after spraying is removed and placed in an oven for drying, so that the heavy rare earth slurry on the inner surface of the annular NdFeB magnet is solidified to form a heavy rare earth coating;

[0047] e. Diffusion and aging treatment: The annular NdFeB magnet with heavy rare earth coating sprayed on both the inner and outer surfaces is then subjected to diffusion and aging treatment under vacuum or inert gas protection to improve the coercive force of the NdFeB magnet.

[0048] In step c, the distance between the first spray gun and the surface of the annular NdFeB magnet to be sprayed is 10-100 mm, and the thickness of the heavy rare earth coating on the inner surface of the annular NdFeB magnet is greater than or equal to the thickness of the heavy rare earth layer on the outer surface.

[0049] f. The temperature of the diffusion treatment is 850°C-950°C, the diffusion time is 4-72h, the aging temperature of the aging treatment is 450-650°C, and the aging time is 3-15h.

[0050] The specific operation of lifting the annular NdFeB magnet using the above lifting device is shown in the following embodiment.

[0051] Embodiment 1:

[0052] Pure dysprosium powder is mixed with a resin-type adhesive and a benzene-based diluent to form a heavy rare earth slurry, and the heavy rare earth slurry is loaded into a pressure stirring barrel for stirring. An annular NdFeB magnet with an inner diameter of 5 mm, a wall thickness of 1 mm, and a length of 5 mm is taken and sleeved on the roller. The retractable component on the roller is adjusted so that it is in a propped-up state and props up the annular NdFeB magnet. Then, the roller is turned on to make the annular NdFeB magnet rotate with the roller. The height between the second spray gun and the surface of the annular NdFeB magnet is adjusted to 10 mm. Then, the second spray gun is turned on to spray the heavy rare earth slurry onto the outer surface of the annular NdFeB magnet, and the spraying thickness is controlled to 5 μm. The hot air drying spray gun is turned on to dry the sprayed annular NdFeB magnet, and the hot air drying spray gun is turned off after drying.

[0053] The roller rotation is turned off and the retractable part on the roller is in a retracted state, the supporting mechanism is started so that the annular NdFeB magnet is supported and fixed, and starts to move toward the first spray gun along the axial direction of the roller, the first spray gun is turned on, and the first spray gun starts to spray heavy rare earth slurry all around, and a layer of heavy rare earth slurry is sprayed on the inner surface of the annular NdFeB magnet when the annular NdFeB magnet passes through the first spray gun, and the spraying thickness is controlled at 8μm, then the first spray gun is turned off, and the annular NdFeB magnet after spraying is placed in an oven for drying, and after drying, the annular NdFeB magnet is subjected to 900℃*4h+500℃*3h diffusion and aging treatment in a vacuum furnace, and then the performance after diffusion is taken out for testing, and compared with the performance of the substrate before diffusion.

[0054] Table 1

[0055] Br(KGs) Hcj (KOe) Hk / Hcj Before matrix diffusion 14.4 16.7 0.98 Example 1 14.3 21.1 0.96

[0056] From the analysis of Table 1, it can be seen that after the annular NdFeB magnet in Example 1 is diffused with metal dysprosium using the method of the present application, the remanence is reduced by 0.1 KGs, the coercive force is increased by 4.4 Koe, and the square measurement value changes very little.

[0057] Embodiment 2:

[0058] The operation process is similar to that of Example 1, but the composition of the heavy rare earth slurry and the specifications of the annular NdFeB magnet are different. Terbium hydride powder is mixed with a resin-type adhesive and a ketone diluent to form a heavy rare earth slurry, and an annular NdFeB magnet with an inner diameter of 20 mm, a wall thickness of 10 mm, and a length of 100 mm is selected.

[0059] The height between the second spray gun and the surface of the annular NdFeB magnet was adjusted to 50mm, the outer surface spraying thickness of the annular NdFeB magnet was controlled to 50μm, and the inner surface spraying thickness of the annular NdFeB magnet was controlled to 80μm. After drying, the annular NdFeB magnet was diffused and aged in a vacuum furnace at 850℃*72h+450℃*15h, and then the performance after diffusion was tested and compared with the substrate performance before diffusion.

[0060] Table 2

[0061] Br(KGs) Hcj(KOe) Hk / Hcj Before matrix diffusion 13.8 19.7 0.98 Example 1 13.5 29.5 0.96

[0062] From the analysis of Table 2, it can be seen that after the annular NdFeB magnet in Example 2 is diffused with terbium hydride using the method of the present application, the remanence is reduced by 0.3 KGs, the coercive force is increased by 9.8 Koe, and the square measurement value changes very little.

[0063] Embodiment 3:

[0064] The operation process is similar to that of Example 1, but the composition of the heavy rare earth slurry and the specifications of the annular NdFeB magnet are different. Terbium copper alloy powder is mixed with a resin-type adhesive and an ester diluent to form a heavy rare earth slurry, and an annular NdFeB magnet with an inner diameter of 30 mm, a wall thickness of 15 mm, and a length of 50 mm is obtained.

[0065] The height between the second spray gun and the surface of the annular NdFeB magnet is adjusted to 100mm, the thickness of the outer surface of the annular NdFeB magnet sprayed is controlled to 100μm, and the thickness of the inner surface of the annular NdFeB magnet sprayed is controlled to 130μm. After drying, the annular NdFeB magnet is diffused and aged at 950℃*30h+650℃*10h in a vacuum furnace, and then the performance after diffusion is taken out for testing and compared with the substrate performance before diffusion.

[0066] Table 3

[0067] Br(KGs) Hcj (KOe) Hk / Hcj Before matrix diffusion 14.1 15.2 0.98 Example 1 13.9 24.3 0.96

[0068] From the analysis of Table 3, it can be seen that after the annular NdFeB magnet in Example 3 is diffused with terbium copper alloy using the method of the present application, the remanence is reduced by 0.2 KGs, the coercive force is increased by 9.1 Koe, and the square measurement value changes very little.

[0069] It can be seen from the above embodiments that a layer of heavy rare earth coating can be sprayed on the inner and outer surfaces of the annular NdFeB magnet by the method of the present application, and after diffusion aging treatment, the coercive force of the NdFeB magnet can be significantly improved, and the remanence of the NdFeB magnet decreases very little.

[0070] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0071] In addition, it should be understood that although the present specification is described in terms of implementation modes, not every implementation mode contains an independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A ring-shaped NdFeB magnet coercivity enhancement device, its characteristic structure include: A sealed chamber (2), a fixed base (3) at the bottom of the sealed chamber (2), and a plurality of fixed support frames (4) mounted on the fixed base (3); a roller (5) is vertically arranged at an upper position of a side wall of the fixed support frame (4), and the roller (5) can rotate around its axial center line under the control of a motor; a retractable component (7) is mounted on the outer surface of the roller (5), and the retractable component (7) can switch between a retracted state and a supporting state, and when the retractable component (7) is in the supporting state, the retractable component (7) is in the supporting state. The annular neodymium iron boron magnet (11) is supported, and when the retractable component (7) is in a retracted state, the annular neodymium iron boron magnet (11) is released; the slide rail (6) is vertically arranged at the lower position of the side wall of the fixed support frame (4), and the axial direction of the slide rail (6) is parallel to the axial direction of the roller (5), and the slide rail (6) can reciprocate up and down along the axial direction of the fixed support frame (4) under the control of the motor; a V-shaped support groove (9) is provided on the slide rail (6), and the V-shaped support groove (9) can be moved along the axis of the slide rail (6) The roller (5) is provided with a first spray gun (8), which is arranged at an axial end of the roller (5) away from the fixed support frame (4); the second spray gun (10) and the hot air drying spray gun (12) are arranged above the roller (5) and can move in a plane parallel to the roller (5); the first spray gun (8) and the second spray gun (12) are arranged above the roller (5) and can move in a plane parallel to the roller (5); the first spray gun (8) and the second spray gun (12) are arranged above the roller (5) and can move in a plane parallel to the roller (5); the first spray gun (8) and the second The spray guns (10) are both air pressure atomizing spray guns. One end of the first spray gun (8) and one end of the second spray gun (10) are respectively connected to the pressure stirring barrel (1) through a pipeline. The other end of the first spray gun (8) and the other end of the second spray gun (10) are respectively connected to their respective nozzles. The heavy rare earth slurry in the pressure stirring barrel (1) is atomized by air pressure and then sprayed out. The spraying direction of the first spray gun (8) is perpendicular to the spray gun direction and can spray in all directions at the same time. The spraying direction of the second spray gun (10) is parallel to the spray gun direction.

2. A device for increasing the coercive force of an annular NdFeB magnet as claimed in claim 1, characterized in that: The number of the fixed support frames (4) is one or more, each fixed support frame (4) is mounted with a roller, different fixed support frames (4) are arranged parallel to each other, and the spacing between different fixed support frames (4) can be adjusted.

3. A method for increasing the coercive force of an annular NdFeB magnet, using the device as claimed in claim 1 or 2, characterized in that: The following steps are included: a. Preparation of heavy rare earth slurry: heavy rare earth powder R, an organic binder and an organic solvent are mixed to prepare heavy rare earth slurry, and the heavy rare earth slurry is placed in a pressure stirring barrel (1); b. Installation of the annular NdFeB magnet: adjusting the retractable component (7) on the roller (5) to a retracted state, installing the annular NdFeB magnet (11) to be sprayed on the roller (5), and adjusting the retractable component (7) to a propped-up state so that the annular NdFeB magnet (11) to be sprayed is propped up and fixed, and starting the roller (5) rotation program so that the annular NdFeB magnet (11) to be sprayed rotates along with the roller (5); c. Preparation of the heavy rare earth coating on the outer surface of the annular NdFeB magnet: move the second spray gun (10) to the position directly above the annular NdFeB magnet (11) to be sprayed, and adjust the distance between the second spray gun (10) and the annular NdFeB magnet (11), then start the second spray gun (10) to spray the heavy rare earth slurry on the outer surface of the annular NdFeB magnet (11), after the spraying is completed, close the second spray gun (10) and start the hot air drying spray gun (12) to perform hot air drying on the annular NdFeB magnet, so that the heavy rare earth slurry sprayed on the outer surface of the annular NdFeB magnet is solidified to form a layer of heavy rare earth coating, and after the coating is solidified, close the self-rotation program of the roller (5); d. Preparation of the heavy rare earth coating on the inner surface of the annular NdFeB magnet: Start the slide rail (6) to drive the V-shaped support groove (9) to move upward along the fixed support frame (4) until the V-shaped support groove (9) completely supports the annular NdFeB magnet (11), adjust the retractable component (7) on the roller (5) to be in a retracted state, so that the annular NdFeB magnet (11) is separated from the roller (5); start the control motor so that the V-shaped support groove (9) supports the annular NdFeB magnet (11) 1) moving in the direction of the first spray gun (8) at the top of the roller (5), and simultaneously turning on the first spray gun (8), so that the first spray gun (8) starts to spray heavy rare earth slurry in all directions, and when passing through the first spray gun (8), a layer of heavy rare earth slurry is sprayed on the inner surface of the annular NdFeB magnet (11), and the annular NdFeB magnet after spraying is removed and placed in an oven for drying, so that the heavy rare earth slurry on the inner surface of the annular NdFeB magnet (11) is solidified to form a heavy rare earth coating; e. Diffusion and aging treatment: The annular NdFeB magnet (11) with heavy rare earth coating sprayed on both the inner and outer surfaces is subjected to diffusion and aging treatment under vacuum or inert gas protection to improve the coercive force of the NdFeB magnet.

4. A method for improving the coercive force of an annular NdFeB magnet as claimed in claim 3, characterized in that: The component of the heavy rare earth powder R in step a is metal terbium or metal dysprosium, and the heavy rare earth powder R is in the state of pure metal powder, compound powder or alloy powder; the organic adhesive is a resin-type adhesive or a rubber-type adhesive, and the organic solvent is a ketone, benzene or ester solvent.

5. A method for improving the coercive force of an annular NdFeB magnet as claimed in claim 3, characterized in that: The thickness of the heavy rare earth coating sprayed on the inner surface of the annular NdFeB magnet in step d is greater than or equal to the thickness of the heavy rare earth coating sprayed on the outer surface of the annular NdFeB magnet in step c.

6. A method for improving the coercive force of an annular NdFeB magnet as claimed in claim 3, characterized in that: The temperature of the diffusion treatment in step e is 850°C-950°C, the diffusion time is 4-72h, the aging temperature of the aging treatment is 450-650°C, and the aging time is 3-15h.

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