A method for printing a plated halbach magnet with neodymium iron boron magnetic sludge waste

Abstract

The application discloses a method for printing a Halbach magnet with a plating layer by using neodymium iron boron magnetic sludge waste, and relates to the technical field of rare earth permanent magnet manufacturing, and comprises the following steps: S10, cleaning and drying the neodymium iron boron magnetic sludge waste to obtain magnetic sludge waste powder; S20, reducing the magnetic sludge waste powder to obtain regenerated neodymium iron boron magnetic powder; S30, mixing rare earth-based low-melting-point alloy powder with the regenerated neodymium iron boron magnetic powder to obtain regenerated magnetic powder; S40, printing on the working table of a laser 3D printer, in the powder laying process of laser printing, a changeable magnetic field is applied to each layer of powder, then laser printing is carried out, and a plating layer is printed on the circumferential side of the printed magnet body, so that a prefabricated body of the integrated Halbach magnet with the plating layer is printed, then the prefabricated body is subjected to heat treatment and magnetization, and finally the integrated Halbach magnet is formed. The application can print the integrated Halbach magnet with the plating layer.

Description

Technical Field

[0001] This invention relates to the field of rare earth permanent magnet material manufacturing technology, and in particular to a method for printing coated Heilbeck magnets using neodymium iron boron magnetic sludge waste. Background Technology

[0002] Traditional Heilbeck magnets are typically manufactured through a mechanical splicing and bonding process using multiple NdFeB magnets with different magnetic orientations. This process is complex, involves significant interface losses, and has low magnetic energy utilization. While laser 3D printing technology can achieve integrated molding of complex structures, current technologies mostly use conventional sintered NdFeB magnetic powder as raw material. During the printing process, the laser thermal effect easily causes grain coarsening, leading to a significant decrease in magnetic properties. Furthermore, NdFeB magnetic sludge waste is generated during the production and processing of NdFeB permanent magnet materials and contains oil, water, and metals. Mud-like waste materials such as granules are difficult to use directly in traditional sintering processes and are usually treated as solid waste, resulting in the waste of rare earth resources. Although the fine grains of magnetic mud waste are smaller than those of conventional sintered NdFeB magnetic powder, which is beneficial to the rapid melting process of laser 3D printing, the existing technology lacks a regeneration process for magnetic mud waste and a method to directly achieve multi-region magnetic orientation control through magnetic field-assisted printing. This restricts the preparation of integrated Heilbeck magnets, and in turn, also restricts the printing preparation of coated integrated Heilbeck magnets. Summary of the Invention

[0003] The purpose of this invention is to provide a method for printing coated Helbeck magnets using neodymium iron boron magnetic sludge waste, which can utilize the prepared recycled magnetic powder to laser 3D print an integrated coated Helbeck magnet.

[0004] To achieve the above objectives, the solution of the present invention is as follows:

[0005] A method for printing coated Helbeck magnets using neodymium iron boron magnetic putty waste includes the following steps:

[0006] S10: After cleaning and drying the NdFeB magnetic mud waste, NdFeB magnetic mud waste powder is obtained;

[0007] S20: Neodymium iron boron magnetic mud waste powder is reduced by calcium thermal reduction method to obtain recycled neodymium iron boron magnetic powder;

[0008] S30: Mix rare earth-based low-melting-point alloy powder with recycled neodymium iron boron magnetic powder to obtain recycled magnetic powder for laser 3D printing;

[0009] S40: Recycled magnetic powder is placed into one of the feed hoppers of the 3D printer, while metal powder is stored in the other feed hoppers. The metal powder is used to print the metal coating. Laser 3D printing is performed on its worktable using a laser 3D printer. The printing process includes the following steps:

[0010] S41: First, lay a single layer of regenerated magnetic powder on the workbench;

[0011] S42: Apply a magnetic field to the single layer of regenerated magnetic powder to give each layer of regenerated magnetic powder magnetic orientation;

[0012] S43: Then, laser 3D printing is used to melt and solidify the single layer of regenerated magnetic powder to form the main body of the magnet;

[0013] S44: After the magnet body cools and solidifies, a metal plating layer is printed on the periphery of the magnet body through a material transfer hopper;

[0014] S50: Repeat steps S41 to S44 on the magnet body to print out a preform of an integrated Helbeck magnet with multiple regions from top to bottom, each region having a different magnetic orientation and a metal coating. Then, the preform is heat-treated to magnetize it, and finally an integrated Helbeck magnet with a metal coating is formed.

[0015] Furthermore, step S10 includes the following steps:

[0016] S11: Wash the NdFeB magnetic mud waste in anhydrous ethanol, then filter out the magnetic mud waste using a filter screen, and then wash the magnetic mud waste in sodium hydroxide solution or sodium bicarbonate solution.

[0017] S12: Separation of neodymium iron boron magnetic mud waste powder from sodium hydroxide solution or sodium bicarbonate solution;

[0018] S13: Heat and dry the separated NdFeB magnetic mud waste powder.

[0019] Furthermore, in step S11, the NdFeB magnetic sludge waste is washed in anhydrous ethanol for 0.5-3 hours, and then washed in a solution of 5% OP emulsifier + 0.5-2 g / L sodium hydroxide or a solution of 5% OP emulsifier + 0.5-8 g / L sodium bicarbonate for 0.5-3 hours.

[0020] Furthermore, step S20 includes the following steps:

[0021] S21: Mix the dried NdFeB magnetic sludge waste powder with metallic calcium powder or calcium hydride powder to obtain a mixed powder, wherein the weight of metallic calcium powder or calcium hydride powder is 10-30% of the NdFeB magnetic sludge waste powder;

[0022] S22: The mixed powder is ball-milled;

[0023] S23: Heat the mixed powder and use the metallic calcium powder or calcium hydride powder in the mixed powder to reduce the neodymium iron boron magnetic mud waste powder;

[0024] S24: Mechanically grind the cooled mixed powder;

[0025] S25: Place the mechanically ground mixed powder into deionized water for washing until no white precipitate appears in the deionized water;

[0026] S26: Separate the NdFeB magnetic mud waste powder from deionized water;

[0027] S27: The separated NdFeB magnetic mud waste powder is dried to obtain recycled NdFeB magnetic powder.

[0028] Furthermore, in step S23, the heating process of the mixed powder is as follows: the mixed powder is placed into a corundum crucible, and then the corundum crucible is placed into a vacuum tube furnace and heated for 3-5 hours at a temperature of 800-1100℃. During the heating process, the vacuum tube furnace uses an argon protective atmosphere or a vacuum environment.

[0029] Furthermore, in step S30, the rare earth-based low-melting-point alloy is smelted from rare earth and low-melting-point metals. The rare earth is selected from one or more of Tb, Dy, Pr, Nd, Ce, and La, and the low-melting-point metal is selected from one or more of Cu, Al, Ga, and Zn.

[0030] Furthermore, the rare earth-based low-melting-point alloy is ball-milled to obtain rare earth-based low-melting-point alloy powder with a particle size of less than 3 micrometers; the recycled NdFeB magnetic powder and the rare earth-based low-melting-point alloy powder are mixed by a three-dimensional mixer, with the content of recycled NdFeB magnetic powder in the recycled magnetic powder accounting for 90-95% and the content of rare earth-based low-melting-point alloy powder accounting for 5-10%.

[0031] Furthermore, in step S50, after the preform of the Helbeck magnet is laser 3D printed, the preform is placed in a vacuum sintering furnace for two heat treatments. After the two heat treatments, the preform is placed in a vacuum atmosphere furnace and sintered at 1x10... -2 The preform is naturally cooled to below 50°C under a vacuum of less than pa, then polished in a polishing machine, and finally magnetized to form an integrated Heilbeck magnet.

[0032] Furthermore, the temperature for the first heat treatment is 300-1000℃, and the temperature for the second heat treatment is 300-600℃.

[0033] Furthermore, Ni, Cu, and Zn metal powders are stored in other silos respectively. In step S44, one of Ni, Ni-Cu-Ni, and Zn plating layers is printed on the periphery of the magnet body so that a preform of an integrated Helbeck magnet with one of Ni, Ni-Cu-Ni, or Zn metal plating layers is printed in step S50.

[0034] After adopting the above solution, the beneficial effects of the present invention are as follows:

[0035] This invention removes impurities and oxide layers from NdFeB magnetic sludge waste through cleaning and calcothermal reduction, transforming it into recycled NdFeB magnetic powder. Rare earth-based low-melting-point alloy powder is then added to the recycled NdFeB magnetic powder to form recycled magnetic powder. Subsequently, a variable magnetic field-assisted laser 3D printing method is used to change the magnetic orientation of the single layer of recycled magnetic powder. The single layer of recycled magnetic powder is melted and solidified by laser printing to form the main body of the magnet. Then, a metal coating is printed on the periphery of the magnet, so that the main body of the magnet has a coating. The above steps are repeated to print an integrated Heilbeck magnet with a metal coating.

[0036] This invention replaces the traditional electroplating process of NdFeB magnets with 3D laser printing of metal coatings, significantly reducing the manufacturing process. It also avoids the increased plating thickness at certain locations due to current concentration during electroplating, effectively improving coating uniformity and eliminating wastewater and exhaust gas generation associated with traditional electroplating processes. Through laser 3D printing, this invention can control the shape and size of the Hellbeck magnet and the thickness of each electroplating layer. Compared to traditional sintered NdFeB magnets, this invention eliminates machining processes and avoids the waste of NdFeB magnets during machining. Furthermore, by controlling the thickness of the electroplating layer, the desired pattern can be left on the magnet surface, replacing laser marking and reducing the number of processes.

[0037] This invention uses the calcium thermal reduction method for recovery, which is simpler and less environmentally polluting than hydrometallurgical technology.

[0038] Because the recycled NdFeB magnetic powder has a small grain size, this invention can effectively reduce the abnormal growth of NdFeB magnet grains during the laser melting process of laser 3D printing. In addition, the rare earth-based low-melting-point alloy can also suppress the abnormal growth of NdFeB magnet grains during the laser melting process of laser 3D printing. The combination of the two effectively overcomes the problem of abnormal growth of NdFeB magnet grains during laser 3D printing and avoids the problem of significant decrease in the magnetic properties of the printed Heilbeck magnet.

[0039] The rare earth-based low-melting-point alloy added in this invention can better construct the grain boundary phase and tightly bind the NdFeB grains together.

[0040] The rare earth-based low-melting-point alloy added in this invention can undergo grain boundary diffusion during subsequent annealing, thereby improving the coercivity of the Heilbeck magnet. Compared with the traditional grain boundary diffusion method, it avoids the accumulation of heavy rare earth on the magnet surface, improves the utilization rate of heavy rare earth, and enhances the magnetic properties of the Heilbeck magnet while using less heavy rare earth.

[0041] This invention can also recycle NdFeB magnetic sludge waste, reducing the waste of rare earth resources. Compared with the traditional splicing and gluing Helbeck magnet manufacturing process, the manufacturing process of Helbeck magnets in this invention is simpler and more efficient. Attached Figure Description

[0042] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0043] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] like Figure 1 As shown, the present invention provides a method for printing coated Helbeck magnets using neodymium iron boron magnetic putty waste, comprising the following steps:

[0045] S10: After cleaning and drying the NdFeB magnetic mud waste, NdFeB magnetic mud waste powder is obtained;

[0046] S20: Neodymium iron boron magnetic mud waste powder is reduced by calcium thermal reduction method to obtain recycled neodymium iron boron magnetic powder;

[0047] S30: Mix rare earth-based low-melting-point alloy powder with recycled neodymium iron boron magnetic powder to obtain recycled magnetic powder for laser 3D printing;

[0048] S40: Recycled magnetic powder is placed into one of the feed hoppers of the 3D printer, while metal powder is stored in the other feed hoppers. The metal powder is used to print the metal coating. Laser 3D printing is performed on its worktable using a laser 3D printer. The printing process includes the following steps:

[0049] S41: First, lay a single layer of regenerated magnetic powder on the workbench;

[0050] S42: Apply a magnetic field to the single layer of regenerated magnetic powder to give each layer of regenerated magnetic powder magnetic orientation;

[0051] S43: Then, laser 3D printing is used to melt and solidify the single layer of regenerated magnetic powder to form the main body of the magnet;

[0052] S44: After the magnet body cools and solidifies, a metal plating layer is printed on the periphery of the magnet body through a material transfer hopper;

[0053] S50: Repeat steps S41 to S44 on the magnet body to print out a preform of an integrated Helbeck magnet with multiple regions from top to bottom, each region having a different magnetic orientation and a metal coating. Then, the preform is heat-treated to magnetize it, and finally an integrated Helbeck magnet with a metal coating is formed.

[0054] Specifically, neodymium iron boron magnetic sludge waste is a mud-like waste material containing neodymium iron boron powder generated during the processing of neodymium iron boron.

[0055] Furthermore, step S10 includes the following steps:

[0056] S11: Wash the NdFeB magnetic mud waste in anhydrous ethanol, then filter out the magnetic mud waste using a filter screen, and then wash the magnetic mud waste in sodium hydroxide solution or sodium bicarbonate solution.

[0057] S12: Separation of neodymium iron boron magnetic mud waste powder from sodium hydroxide solution or sodium bicarbonate solution;

[0058] S13: Heat and dry the separated NdFeB magnetic mud waste powder.

[0059] Furthermore, in step S11, the NdFeB magnetic sludge waste is washed in anhydrous ethanol for 0.5-3 hours, and then washed in a 5% OP emulsifier + 0.5-2 g / L sodium hydroxide solution or a 5% OP emulsifier + 0.5-8 g / L sodium bicarbonate solution for 0.5-3 hours; specifically, the 5% in the 5% OP emulsifier is a mass percentage.

[0060] Specifically, in step S11, an ultrasonic cleaner is used for ultrasonic cleaning during the cleaning process, and the entire cleaning process is repeated 3-5 times; in step S12, a magnetic separator is used to separate the NdFeB magnetic sludge waste powder from the sodium hydroxide solution or sodium bicarbonate solution; in step S13, a vacuum drying oven is used to heat and dry the NdFeB magnetic sludge waste powder that has been cleaned and separated, and the oxygen concentration in the vacuum drying oven is less than 300 ppm.

[0061] Furthermore, step S20 includes the following steps:

[0062] S21: Mix the dried NdFeB magnetic sludge waste powder with metallic calcium powder or calcium hydride powder to obtain a mixed powder, wherein the weight of metallic calcium powder or calcium hydride powder is 10-30% of the NdFeB magnetic sludge waste powder;

[0063] S22: The mixed powder is ball-milled;

[0064] S23: Heat the mixed powder and use the metallic calcium powder or calcium hydride powder in the mixed powder to reduce the neodymium iron boron magnetic mud waste powder;

[0065] S24: Mechanically grind the cooled mixed powder;

[0066] S25: Place the mechanically ground mixed powder into deionized water for washing until no white precipitate appears in the deionized water;

[0067] S26: Separate the NdFeB magnetic mud waste powder from deionized water;

[0068] S27: The separated NdFeB magnetic mud waste powder is dried to obtain recycled NdFeB magnetic powder.

[0069] Furthermore, in step S23, the heating process of the mixed powder is as follows: the mixed powder is placed into a corundum crucible, and then the corundum crucible is placed into a vacuum tube furnace and heated for 3-5 hours at a temperature of 800-1100℃. During the heating process, the vacuum tube furnace uses an argon protective atmosphere or a vacuum environment.

[0070] Specifically, in step S21, the mixing process is carried out under a protective atmosphere; in step S22, the mixed powder is ball-milled using a planetary ball mill; in step S23, the vacuum tube furnace uses an argon protective atmosphere or a vacuum environment (vacuum degree less than 1x10⁻⁶) during the heating process. -2 (pa); In step S24, the cooled mixed powder is placed in an argon-protected glove box for mechanical grinding; In step S25, the cleaning process uses an ultrasonic cleaner for ultrasonic cleaning; In step S26, the NdFeB magnetic mud waste powder is separated from the deionized water using a magnetic separator; In step S27, the NdFeB magnetic mud waste powder is placed in a vacuum drying oven for drying.

[0071] Furthermore, in step S30, the rare earth-based low-melting-point alloy is smelted from rare earth and low-melting-point metals. The rare earth is selected from one or more of Tb, Dy, Pr, Nd, Ce, and La, and the low-melting-point metal is selected from one or more of Cu, Al, Ga, and Zn.

[0072] Preferably, the rare earth elements are selected from Tb and Dy-based low-melting-point alloys, which can achieve grain boundary diffusion during the subsequent annealing process, further improving the coercivity of the 3D printed magnet.

[0073] Furthermore, the rare earth-based low-melting-point alloy is ball-milled to obtain rare earth-based low-melting-point alloy powder with a particle size of less than 3 micrometers; the recycled NdFeB magnetic powder and the rare earth-based low-melting-point alloy powder are mixed by a three-dimensional mixer, with the content of recycled NdFeB magnetic powder in the recycled magnetic powder accounting for 90-95% and the content of rare earth-based low-melting-point alloy powder accounting for 5-10%.

[0074] Specifically, a high-energy ball mill is used to pulverize rare earth-based low-melting-point alloys.

[0075] Furthermore, in step S50, after the preform of the Helbeck magnet is laser 3D printed, the preform is placed in a vacuum sintering furnace for two heat treatments. After the two heat treatments, the preform is placed in a vacuum atmosphere furnace and sintered at 1x10...-2 The preform is naturally cooled to below 50°C under a vacuum of less than pa, then polished in a polishing machine, and finally magnetized to form an integrated Heilbeck magnet.

[0076] Furthermore, the temperature of the first heat treatment is 300-1000℃, and the temperature of the second heat treatment is 300-600℃; the purpose of heat treatment is to optimize the grain boundary structure inside the magnet and improve the performance of the magnet.

[0077] Furthermore, Ni, Cu, and Zn metal coating powders are stored in other silos respectively. In step S44, one of Ni, Ni-Cu-Ni, and Zn coatings is printed on the periphery of the magnet body so that a preform of an integrated Helbeck magnet with one of Ni, Ni-Cu-Ni, or Zn metal coatings is printed in step S50.

[0078] Furthermore, before printing the coating, the Ni, Cu, and Zn coating metals need to be ball-milled to obtain coating metal powder with a particle size of less than 3 μm. It is understood that the present invention preferably uses Ni, Cu, and Zn as coating metals, but is not limited to these three metals.

[0079] Specifically, in the Ni-Cu-Ni coating, the thickness of the bottom Ni coating is 1.5-7μm, the thickness of the Cu coating is 2.5-10μm, and the thickness of the surface Ni is 1.5-8μm.

[0080] Furthermore, when printing each magnet body and coating layer, the size of the printed magnet body and the thickness of each coating layer can be changed.

[0081] Specifically, before laser 3D printing, the 3D drawing of the Heilbeck magnet preform is first input into the 3D printer; the printing chamber of the laser 3D printer is protected by a protective atmosphere or selected as a vacuum during the printing process, with an oxygen content of less than 400ppm; the thickness of a single powder layer is 10-50μm; during the powder layering process, a pulsed electromagnet is used to apply a magnetic field to each layer of powder to make the powder form a magnetic orientation, and the orientation of the magnetic field can be changed.

[0082] Specifically, the laser printing power is 20W-200W; the laser spot diameter is 10-50µm; the laser scanning spot spacing is 10-150µm; the laser scanning spacing is 30-450µm; and the laser scanning speed is 10-100mm / s.

[0083] Specifically, the vacuum sintering furnace uses a touch screen operating interface and intelligent control, and has internal temperature measuring equipment, which makes it convenient for operators to monitor the operating status of the equipment, the real-time temperature inside the furnace, and adjust the heating rate.

[0084] Preferably, the vacuum degree in the vacuum sintering furnace should be less than 1 x 10⁻⁶ during the heating process. -2 Preferably, during the heating stage of the vacuum sintering furnace, the heating rate is 5-10℃ / min.

[0085] Preferably, the polishing machine is a vibratory polishing machine, the polishing abrasive is a fine grinding abrasive, such as micron-sized diamond powder or high-frequency ceramic grinding stone, and the polishing fluid contains an antioxidant.

[0086] Specifically, it also includes the following steps:

[0087] Machine vision is used to capture the position and shape of the prefabricated Helbeck magnet. The captured information is then transmitted to a high-performance computer. The computer analyzes and calculates the information and transmits it to the robotic arm, which then performs position calibration on the magnet.

[0088] The automated equipment and the magnetizer are on an automated production line. After the automated equipment completes the arrangement of the magnet parts, the pre-formed Helbeck magnets are sequentially placed into the magnetizing fixture by the conveyor belt and then magnetized by the magnetizer.

[0089] Preferably, the magnetizing fixture is a planar multi-pole magnetizer, which can magnetize the preform of the Heilbeck magnet into an integrated Heilbeck magnet in one go.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the design of this case. All equivalent changes made based on the key design features of this case shall fall within the protection scope of this case.

Claims

1. A method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste, characterized in that: Includes the following steps: S10: After cleaning and drying the NdFeB magnetic mud waste, NdFeB magnetic mud waste powder is obtained; S20: Neodymium iron boron magnetic mud waste powder is reduced by calcium thermal reduction method to obtain recycled neodymium iron boron magnetic powder; S30: Mix rare earth-based low-melting-point alloy powder with recycled neodymium iron boron magnetic powder to obtain recycled magnetic powder for laser 3D printing; S40: Recycled magnetic powder is placed into one of the feed hoppers of the 3D printer, while metal powder is stored in the other feed hoppers. The metal powder is used to print the metal coating. Laser 3D printing is performed on its worktable using a laser 3D printer. The printing process includes the following steps: S41: First, lay a single layer of regenerated magnetic powder on the workbench; S42: Apply a magnetic field to the single layer of regenerated magnetic powder to give each layer of regenerated magnetic powder magnetic orientation; S43: Then, laser 3D printing is used to melt and solidify the single layer of regenerated magnetic powder to form the main body of the magnet; S44: After the magnet body cools and solidifies, a metal plating layer is printed on the periphery of the magnet body through a material transfer hopper; S50: Repeat steps S41 to S44 on the magnet body to print out a preform of an integrated Helbeck magnet with multiple regions from top to bottom, each region having a different magnetic orientation and a metal coating. Then, the preform is heat-treated to magnetize it, and finally an integrated Helbeck magnet with a metal coating is formed.

2. The method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste as described in claim 1, characterized in that: Step S10 includes the following steps: S11: Wash the NdFeB magnetic mud waste in anhydrous ethanol, then filter out the magnetic mud waste using a filter screen, and then wash the magnetic mud waste in sodium hydroxide solution or sodium bicarbonate solution. S12: Separation of neodymium iron boron magnetic mud waste powder from sodium hydroxide solution or sodium bicarbonate solution; S13: Heat and dry the separated NdFeB magnetic mud waste powder.

3. The method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste as described in claim 2, characterized in that: In step S11, the NdFeB magnetic sludge waste is washed in anhydrous ethanol for 0.5-3 hours, and then washed in a 5% OP emulsifier + 0.5-2 g / L sodium hydroxide solution or a 5% OP emulsifier + 0.5-8 g / L sodium bicarbonate solution for 0.5-3 hours.

4. The method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste as described in claim 1, characterized in that: Step S20 includes the following steps: S21: Mix the dried NdFeB magnetic sludge waste powder with metallic calcium powder or calcium hydride powder to obtain a mixed powder, wherein the weight of metallic calcium powder or calcium hydride powder is 10-30% of the NdFeB magnetic sludge waste powder; S22: The mixed powder is ball-milled; S23: Heat the mixed powder and use the metallic calcium powder or calcium hydride powder in the mixed powder to reduce the neodymium iron boron magnetic mud waste powder; S24: Mechanically grind the cooled mixed powder; S25: Place the mechanically ground mixed powder into deionized water for washing until no white precipitate appears in the deionized water; S26: Separate the NdFeB magnetic mud waste powder from deionized water; S27: The separated NdFeB magnetic mud waste powder is dried to obtain recycled NdFeB magnetic powder.

5. The method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste as described in claim 4, characterized in that: In step S23, the heating process of the mixed powder is as follows: the mixed powder is placed into a corundum crucible, and then the corundum crucible is placed into a vacuum tube furnace and heated for 3-5 hours at a temperature of 800-1100℃. During the heating process, the vacuum tube furnace uses an argon protective atmosphere or a vacuum environment.

6. The method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste as described in claim 1, characterized in that: In step S30, the rare earth-based low-melting-point alloy is smelted from rare earth and low-melting-point metal. The rare earth is selected from one or more of Tb, Dy, Pr, Nd, Ce, and La, and the low-melting-point metal is selected from one or more of Cu, Al, Ga, and Zn.

7. The method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste as described in claim 6, characterized in that: Rare earth-based low-melting-point alloys are ball-milled to obtain rare earth-based low-melting-point alloy powder with a particle size of less than 3 micrometers. Regenerated NdFeB magnetic powder and rare earth-based low-melting-point alloy powder are mixed, with the content of recycled NdFeB magnetic powder in the recycled magnetic powder being 90-95% and the content of rare earth-based low-melting-point alloy powder being 5-10%.

8. The method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste as described in claim 1, characterized in that: In step S50, after the preform of the Helbeck magnet is laser 3D printed, the preform is placed in a vacuum sintering furnace for two heat treatments. After the two heat treatments, the preform is placed in a vacuum atmosphere furnace and sintered at 1x10... -2 The preform is naturally cooled to below 50°C under a vacuum of less than pa, then polished in a polishing machine, and finally magnetized to form an integrated Heilbeck magnet.

9. The method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste as described in claim 8, characterized in that: The temperature for the first heat treatment is 300-1000℃, and the temperature for the second heat treatment is 300-600℃.

10. The method for printing coated Heilbeck magnets using neodymium iron boron magnetic putty waste as described in claim 1, characterized in that: Ni, Cu, and Zn metal powders are stored in other silos. In step S44, one of Ni, Ni-Cu-Ni, and Zn plating is printed on the periphery of the magnet body so that in step S50, a preform of an integrated Helbeck magnet with one of Ni, Ni-Cu-Ni, or Zn metal plating is printed.

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