Patent Grant
12100544
The present invention relates to a technical field of a process of NdFeB magnet, and more specifically is about a device and method of improving coercivity of the ring-shaped NdFeB magnet.
Since an appearing of NdFeB magnets in 1983, it has been widely used in fields of computers, automobiles, medical treatment and wind power generation. A ring-shaped NdFeB magnet has a higher application in a motor field due to its special shape and orientation direction and can achieve better motor performance. A motor will generate heat in a process of high-speed rotation, resulting in a continuous weakening of a magnetism of NdFeB magnets, affecting the performance of the motor. Therefore, in order to avoid a weakening of the magnetism of NdFeB magnets, it is necessary to improve a coercivity of NdFeB magnets applied to the motor.
Adding Dy, Tb or its alloy at a boundary of a Nd2Fe14B phase can increase a crystalline magnetic anisotropy of the Nd2Fe14B phase, which can effectively improve the coercivity of the NdFeB magnets. Based on this theory, a grain boundary diffusion technology is developed. Because of an excellent performance improvement advantages and high economic value of the grain boundary diffusion technology, it has been widely used in a production and processing of NdFeB magnets, and it evolved different ways of diffusion. However, due to a special shape of the ring-shaped NdFeB magnet, the current diffusion methods are unable to effectively and well realize the low-cost and efficient heavy rare earth diffusion to the ring-shaped NdFeB magnet to improve its coercivity.
The document CN106782980A of Baotou Tianhe Magnetic Materials Technology Co. Ltd discloses a method of using heavy rare earth salt solution as electroplating solution, a layer of heavy rare earth coating is electroplated on a surface of NdFeB magnet, and then magnetic properties are improved by high temperature diffusion. This method is suitable for NdFeB magnet with any one shape of square, tile type, steamed buns type, radiation ring and so on. The method has higher versatility. However, this method also has some defects. On the one hand, the electroplating solution of heavy rare earth is easy to oxidize, On the other hand, an existence of a nip and edge effect during a plating process also affects an uniformity of the heavy rare earth film.
In order to solve a problem that a ring-shaped NdFeB magnet is not easy to be diffused, some embodiments of the present invention provide a device and method for improving coercivity of the ring-shaped NdFeB magnets for homogenization, stabilization, batch production of the ring-shaped NdFeB magnets.
Some embodiments of the present invention adopts the following technical solution:
Some embodiments of the present invention provides a device for improving the coercivity of the ring-shaped NdFeB magnet, it includes a sealed chamber, and wherein the device includes: a plurality of plural fixed support frames disposed in the sealed chamber, a roller with a retractable member, wherein each of the plurality of fixed support frame is equipped with the roller, the retractable member is located on a side wall of the roller and switches between a contracted state and a supporting state; a first spray gun provided at an end of the roller; a sliding rail, wherein each fixed support frame is also provided with the sliding rail, the sliding rail is provided with a support groove, the support groove is configured to reciprocate along the sliding rail; and a second spray gun and a hot air drying spray gun disposed on one side of the roller.
In some embodiments, the device also includes a pressure mixing barrel, the first spray gun and the second spray gun are air pressure atomizing spray gun, the heavy rare earth slurry in the pressure mixing barrel is atomized and sprayed by spray gun and spray gun; a spraying direction of the first spray gun is perpendicular to a spray gun direction and is sprayed around at the same time; the spraying direction of the second spray gun is parallel to the spray gun direction, the first spray gun and the second spray gun are connected with the pressure mixing barrel, the second spray gun and hot air drying spray gun are located directly above the roller and is configured to move back and forth in the plane parallel to the roller.
In some embodiments, the device includes a fixed base disposed in the sealed chamber, bottoms of the plurality of fixed support frames are respectively installed on the fixed base, and the plurality of fixed support frames are arranged in parallel with each other and the distance between two fixed support frames is adjustable.
In some embodiments, the device comprises: a motor, the roller rotates under a control of the motor, and the slide rail is configured to reciprocate up and down along the fixed support frame under a control of the motor, each roller is vertically fixed on a side wall of a corresponding fixed support frame, and the different rollers are arranged in parallel with each other.
In some embodiments, the support groove is disposed in a V-shaped or corrugated shape or with a protrusion on a surface of the support groove, and the supporting groove is located directly below the roller.
Some embodiments of the present invention provide a method for improving the coercivity of the ring-shaped NdFeB magnet, wherein the method includes the following steps:
In some embodiments, in step a, the component of the heavy rare earth powder R includes pure Dy powder, pure Tb powder, Dy alloy powder, Tb alloy powder, Dy compound powder and Tb compound powder; an organic binder is a resin type adhesive or a rubber type adhesive, an organic solvent is a ketone, a benzene or a ester solvent.
In some embodiments, the rotating mechanism in step b includes a roller and a retractable member located on a side wall of the roller, the plurality of ring-shaped NdFeB magnets are sleeved on the retractable member, and then the retractable member is adjusted to be in a supporting state so that the plurality of ring-shaped NdFeB magnets are supported on the retractable member.
In some embodiments, the spray gun that sprays the outer surface of the ring-shaped NdFeB magnet is called the second spray gun, and there is a distance between the second spray gun and the outer surface of the ring-shaped NdFeB magnet to be sprayed.
In some embodiments, in step d, adjust the retractable member to be in a contracted state, so that the plurality of ring-shaped NdFeB magnets is separated from a support of the retractable member.
In some embodiments, the spray gun for spraying the inner surface of the plurality of ring-shaped NdFeB magnets in step d is called the first spray gun, the support mechanism controls a movement of the plurality of ring-shaped NdFeB magnets to a position where the first spray gun located, the support mechanism includes a support frame, a sliding rail that moves up and down along the support frame, the support groove for supporting the plurality of ring-shaped NdFeB magnets, when the plurality of ring-shaped NdFeB magnets is separated from the roller, the supporting groove drives the plurality of ring-shaped NdFeB magnets to move along the sliding rail to the first spray gun; a thickness of the heavy rare earth coating on the inner surface of the ring-shaped NdFeB magnet is greater than or equal to a thickness of the heavy rare earth layer on the outer surface.
In some embodiments, a temperature of a diffusion treatment in step f is 850° C.-950° C., and a diffusion time is 4-72 h, the aging temperature of a aging treatment is 450-650° C., and a aging time is 3-15 h.
Compared with the prior art, the present invention has the following advantages:
Using the device and the method disclosed in the present invention, a layer of heavy rare earth slurry can be quickly coated on the inner and outer surfaces of the ring-shaped NdFeB magnet, and after diffusion, the coercivity of the ring-shaped NdFeB magnet can be greatly improved. In addition, compared with the existing methods of electrophoresis, electroplating, etc., which can realize the diffusion of ring-shaped NdFeB magnets, heavy rare earth coating obtained on the outer surface and inner surface of the ring-shaped NdFeB magnet using the present invention is more uniform, and the thickness of film layer is more controllable, and the coercivity of the ring-shaped NdFeB magnet after diffusion is more uniform.
Herein, the drawings include the following drawing markers:
1. pressure mixing barrel, 2. sealing chamber, 3. fixing base, 4. fixing support frame, 5. roller, 6. slide rail, 7. retractable member,
7-1. retractable member in supporting state, 7-2. retractable member in contracted state, 8. the first spray gun, 9. support groove, 10. the second spray gun, 11. ring-shaped NdFeB magnet, 12. hot air drying spray gun.
The principles and features of the present invention will be described below with reference to the accompanying figures. The explanation of the present invention in the specific embodiments is not intended to limit the scope of the present invention.
As shown in
As shown in
A fixed base 3 is provided at a bottom of the sealed chamber 2, the support frame 4 is provided above the fixed base 3, and the roller 5 is disposed at the upper position of the support frame 4, and the roller 5 is parallel to the bottom end of the sealed compartment 2, and Roller 5 can rotate.
The retractable member 7 is installed on the outer surface of the roller 5, and the plurality of ring-shaped NdFeB magnets are sleeved on the telescopic part 7. The retractable member 7 is a plurality of telescopic rods disposed on the roller 5. The roller 5 and the retractable member 7 are all controlled by the motor. The motor controls the rotation of the roller 5, and the motor controls the contraction and support of the retractable member 7. The retractable member 7 switches between the contracted and supporting states. When the retractable member 7 is in the supporting state, the ring-shaped NdFeB magnet can rotate synchronously with the roller 5, and when the retractable member 7 is in the contracted state, the ring-shaped NdFeB magnet no longer rotates with the roller 5, and the ring-shaped NdFeB magnet is break away from a control of the roller.
In this embodiment, only one roller 5 is installed, and three ring-shaped NdFeB magnets are placed on each roller 5. According to the spraying needs, a plurality of parallel rollers can be disposed, and the plurality of rollers are placed on each roller. The ring-shaped NdFeB magnets on the same roller are coaxial. When there are the plurality of rollers, the number of rollers is not less than 2, and a center distance between the rollers can be adjusted.
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 the plane parallel to the roller 5, and the distance of the second spray gun 10 and the hot air drying spray gun 12 from the roller 5 are adjustable, when the ring-shaped NdFeB magnet is supported by the retractable member 7, the roller 5 drives the ring-shaped NdFeB magnets to rotate, and the second spray gun 10 sprays the heavy rare earth slurry on the outer surface of the ring-shaped NdFeB magnet, the heavy rare earth slurry in the pressure stirring tub 1 is atomized by air pressure and then sprayed, a spray direction of the second spray gun 10 is parallel to a spray gun direction.
The slide rail 6 is provided at the lower part of the support frame 4. The slide rail 6 reciprocates up and down along the fixed support frame 4 through motor control. The slide rail 6 is provided with the support groove 9 for reciprocating along the slide rail 6. The support groove 9 is disposed in a V-shaped or corrugated shape or with protrusions on the surface, The support groove 9 is located directly under the roller 5, and the slide rail 6 drives the support groove 9 to move up and down to a state where the support groove 9 can hold or separate the ring-shaped NdFeB magnet. The support groove 9 can slide back and forth along the slide rail 6, and the support groove 9 is described with the V-shape in this embodiment.
The first spray gun 8 is provided 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 on the same straight line. The first spray gun 8 is used to spray the inner surface of the ring-shaped NdFeB magnet.
Control slide rail 6 moves upward along the fixed support frame 4 until the ring-shaped NdFeB magnets is in contact with the upper surface of the V-shaped support groove 9, and the retractable member 7 is adjusted to the contracted state. At this time, the supporting groove 9 provides support for the ring-shaped NdFeB magnets, and drives the ring-shaped NdFeB magnets to move to the first spray gun 8. When the ring-shaped NdFeB magnets pass through the first spray gun 8, the first spray gun 8 sprays the inner surface of the ring-shaped NdFeB magnet.
When using the device of the present application to increase the coercivity of the ring-shaped NdFeB magnet, follow the steps below:
In step c, the distance between the first spray gun and the surface of the ring-shaped NdFeB magnet to be sprayed is 10-100 mm, and the thickness of the heavy rare earth coating on the inner surface of the ring-shaped NdFeB magnet is greater than or equal to the thickness of the heavy rare earth layer on the outer surface.
In step e, the temperature of the diffusion treatment is 850° C.-950° C., the diffusion time is 4-72 h, the aging temperature of the aging treatment is 450-650° C., and the aging time is 3-15 h.
The specific operation of using the device of the present invention to increase the coercivity of the ring-shaped NdFeB magnet is shown in the following embodiments.
Using pure Dy powder to mix with resin adhesive and benzene diluent to form heavy rare earth slurry, and put the heavy rare earth slurry into the pressure mixing barrel for stirring. Take the ring-shaped NdFeB magnet with an inner diameter of 5 mm, the wall thickness of 1 mm and the length of 5 mm, and disposed the ring-shaped NdFeB magnet on the roller, adjust the retractable member on the roller to make it in the supporting state and support up the ring-shaped NdFeB magnet, then turn on the roller to make the ring-shaped NdFeB magnet rotate with the roller, adjust the distance between the second spray gun and the surface of the ring-shaped NdFeB magnet to 10 mm, and then turn on the second spray gun to spray the heavy rare earth slurry on the outer surface of the ring-shaped NdFeB magnet, and the spraying thickness is controlled to 5 μm, turn on the hot air drying spray gun to dry the sprayed ring-shaped NdFeB magnet, and turn off the hot air drying spray gun after drying.
Turning off the rotation of the roller and make the retractable members on the roller in the contracted state, turn on the support mechanism, so that the ring-shaped NdFeB magnet is supported and fixed, and start to move along the axis of the roller to the first spray gun, turn on the first spray gun, make the first spray gun start spraying heavy rare earth slurry all around. When the ring-shaped NdFeB magnet passes through the first spray gun, a layer of heavy rare-earth slurry is sprayed on the inner surface of the ring-shaped NdFeB magnet, and the spray thickness is controlled at 8 μm. Then turn off the first spray gun, and put the sprayed ring-shaped NdFeB magnet in an oven for drying. After drying, the ring-shaped NdFeB magnet was diffused and aged at 900° C.*4 h+500° C.*3 h in a vacuum furnace. After that, the performance after diffusion was tested and compared with the performance before diffusion.
Analyzing Table 1, it can be seen that after the Dy is diffused in the ring-shaped NdFeB magnet in Example 1, the remanence decreases by 0.01 T, the coercivity increases by 350 KA/m, and the square measurement value changes little.
The operation process is similar to Example 1, but the composition of the heavy rare earth slurry and the specifications of the ring-shaped NdFeB magnet are different.
Using Tb hydride powder mixed with resin adhesive and ketone diluent to form heavy rare earth slurry, the inner diameter of the ring-shaped NdFeB magnet is 20 mm, the wall thickness is 10 mm, and the length is 100 mm.
Adjust the distance between the second spray gun and the surface of the ring-shaped NdFeB magnet to 50 mm. The outer surface spraying thickness of the ring-shaped NdFeB magnet is controlled to 50 μm, and the inner surface spraying thickness of the ring-shaped NdFeB magnet is controlled to 80 μm. The ring-shaped NdFeB magnet was diffused and aged at 850° C.*72 h+450° C.*15 h in a vacuum furnace. After that, the performance after diffusion was tested and compared with the performance before diffusion.
Analyzing Table 2, it can be seen that the remanence of the ring-shaped NdFeB magnet decreases by 0.03 T, and the coercivity increases by 780 KA/m, and the square measurement value changes little.
The operation process is similar to Example 1, but the composition of the heavy rare earth slurry and the specifications of the ring-shaped NdFeB magnet are different. The heavy rare earth slurry is formed by mixing TbCu alloy powder with resin type adhesive and ester diluent.
The inner diameter of the ring-shaped NdFeB magnet is 30 mm, the wall thickness is 15 mm, and the length is 50 mm.
Adjust the distance between the second spray gun and the surface of the ring-shaped NdFeB magnet to 100 mm. The outer surface spraying thickness of the ring-shaped NdFeB magnet is controlled to 100 μm, and the inner surface spraying thickness of the ring-shaped NdFeB magnet is controlled to 130 μm. the ring-shaped NdFeB magnet was diffused and aged at 950° C.*30 h+650° C.*10 h in a vacuum furnace. After that, the performance after diffusion was tested and compared with the performance before diffusion.
Analyzing Table 3, it can be seen that the remanence of the ring-shaped NdFeB magnet decreases by 0.02 T, and the coercivity increases by 724 KA/m, and the square measurement value changes little.
It can be seen from the above embodiments that the device and method of the present invention can be used to spray a layer of heavy rare earth coating on the inner and outer surfaces of the ring-shaped NdFeB magnet, and after the diffusion treatment, the coercivity of NdFeB magnet can be significantly improved, and the remanence of the NdFeB magnet decreases very little.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202010214860.0 | Mar 2020 | CN | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20150086710 | Takagi | Mar 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 208679571 | Apr 2019 | CN |
| 2013-042152 | Feb 2013 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20210304960 A1 | Sep 2021 | US |
