Preparation method of multi-pole radial magnetizing product

Abstract

The invention discloses a preparation method of a multi-pole radial magnetizing product, which specifically comprises the following steps: powder preparation, primary pressing, magnetizing orientation, secondary pressing, sintering and tempering, and surface treatment and magnetizing detection, and relates to the technical field of magnetic material production and preparation. According to the preparation method of the multi-pole radial magnetizing product, through unique process steps and parameter control, the problems that in the prior art, the utilization rate of radial cylinder manufacturing materials is low, and multi-pole magnetizing mass production cannot be achieved are solved, and powerful technical support is provided for development of neodymium iron boron magnetic materials in the high-end application field.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic material production and preparation, in particular to a method for preparing a multi-pole radial magnetization product. Background Art

[0002] As a type of permanent magnet material with the highest magnetic energy product, rare earth permanent magnet NdFeB enjoys the reputation of "King of Magnets" and is widely used in many fields such as energy, transportation, and communications. According to statistics, more than 60% of NdFeB permanent magnet materials are used to manufacture various types of permanent magnet motors. Compared with traditional motors, permanent magnet motors have significant advantages such as small size, low noise, and high energy efficiency.

[0003] As one of the world's largest NdFeB production and export bases, China has a complete industrial chain and technological advantages. At present, the NdFeB industry is developing in the direction of material technology upgrades and high-end application popularization. In the future, in the fields of new energy vehicles, high-speed motors, energy-saving home appliances, robots and other intelligent equipment, the demand for NdFeB magnets is expected to continue to grow, and the market prospects are very broad.

[0004] With the rapid development of high-speed motors, drones, humanoid robots and other fields, the demand for NdFeB radial ring products is increasing, and the advantages of four-pole magnetization and radiation magnetization rings are becoming more and more prominent. However, the existing radial cylinder manufacturing process mostly adopts the square rolling method, which has the problem of low material utilization and can only achieve two-pole magnetization. At present, four-pole and radiation magnetization technologies have not yet been mass-produced, and cannot meet the market demand for high-performance, multi-pole magnetized NdFeB products. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for preparing a multi-pole radial magnetization product, which solves the problem that the existing radial cylindrical manufacturing process adopts a square rolling method, has a low material utilization rate, can only achieve two-pole magnetization, and four-pole and radiation magnetization technologies have not yet been mass-produced.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for preparing a multi-pole radial magnetization product, specifically comprising the following steps:

[0007] Step 1: Powder preparation: Select the shavings that meet the technical requirements and grind them into NdFeB powder using a jet mill. During the grinding process, strictly control the process parameters to ensure uniform powder particle size. After grinding, use high-efficiency stirring equipment to fully stir the powder to make it evenly mixed to ensure the consistency of subsequent product performance.

[0008] Step 2: Initial pressing: carefully load the uniform powder prepared in step 1 into a cylindrical mold customized in advance according to product design requirements, and use high-precision pressure equipment to press and form. During the pressing process, the pressure and holding time are precisely controlled to ensure that the cylindrical blank has a suitable density and shape stability, laying a good foundation for subsequent processes.

[0009] Step 3: Magnetization and orientation: Gently place the cylindrical product made in step 2 into a carefully designed rubber mold, and then place it in a special magnetizer. During the magnetization process, a high-intensity magnetic field of 3T-6T is applied to allow the NdFeB powder to achieve magnetization orientation under the action of the magnetic field, thereby initially forming a product structure with specific magnetic properties. This step places extremely high demands on the uniformity and stability of the magnetic field of the magnetizer. By optimizing the magnetic field design and control technology of the magnetizer, it is ensured that the product obtains uniform and consistent magnetic properties during the magnetization process.

[0010] Step 4: Secondary pressing: The magnetized and oriented product is pressed again using the cold isostatic pressing process. During the cold isostatic pressing process, the internal structure of the product is made denser by precisely controlling the pressure, holding time, and uniformity of pressure application, further improving the density and magnetic stability of the product, while eliminating the problem of uneven internal stress that may exist during the initial pressing process.

[0011] Step 5, sintering and tempering; carefully place the product pressed in step 4 into a vacuum sintering furnace. During the sintering process, the heating is strictly carried out according to the preset temperature rise curve to achieve densification sintering of the product at high temperature. After sintering is completed, tempering treatment is immediately carried out. By precisely controlling the tempering temperature and time, the organizational structure and magnetic properties of the product are adjusted, the residual stress generated during the sintering process is eliminated, and the toughness and comprehensive magnetic properties of the product are improved. After completing the sintering and tempering treatments, the product is taken out of the furnace and made into a blank column;

[0012] Step 6, surface treatment and magnetization detection: polish the surface of the blank column obtained in step 5, remove the oxide layer and uneven parts on the surface, so that the surface of the product meets the required smoothness requirements, and then put it into a multi-stage magnetizer for magnetization. After the magnetization is completed, the product is fully tested. Specific testing items include surface magnetic detection at all levels, using a high-precision Gauss meter to measure the surface magnetic field strength of each pole face of the product and record the data, and at the same time perform magnetic line distribution detection, using advanced magnetic line detection equipment to intuitively observe and analyze the distribution of the product's magnetic line of force, to ensure that the product's magnetic line of force is evenly distributed and the performance of each pole is consistent. Only products that pass strict testing can enter the subsequent packaging and application links.

[0013] Preferably, in the step 1, the powder has a particle size of 1-6 um, and the stirring time is 20-50 minutes, and the stirring speed is 200 rpm.

[0014] Preferably, the compaction density in step 2 is 2.5-3.5 g / cm 3 , and the pressure is 5-20MPa.

[0015] Preferably, the magnetization time in step three is 2-10 seconds.

[0016] Preferably, the cold isostatic pressing pressure in step 4 is 200 MPa, and the holding time is 15 minutes.

[0017] Preferably, the five empty sintering furnaces in the steps are heated at a rate of 3°C-5°C / min, with a temperature of 600-1100°C and kept warm for 2-3 hours.

[0018] The present invention provides a method for preparing a multi-pole radial magnetization product. Compared with the prior art, it has the following beneficial effects:

[0019] This method for preparing multi-pole radial magnetization products, through unique process steps and parameter control, solves the problems of low material utilization rate in radial cylindrical manufacturing and inability to achieve multi-pole magnetization mass production in the prior art, and provides strong technical support for the development of NdFeB magnetic materials in high-end application fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] See also Figure 1 The embodiment of the present invention provides a technical solution: a method for preparing a multi-pole radial magnetization product, which specifically includes the following steps:

[0023] Step 1: Powder preparation: Select the shavings that meet the technical requirements and grind them into NdFeB powder using a jet mill. During the grinding process, strictly control the process parameters to ensure uniform powder particle size. After grinding, use high-efficiency mixing equipment to fully stir the powder to make it evenly mixed to ensure the consistency of subsequent product performance.

[0024] Step 2: Initial pressing: carefully load the uniform powder prepared in step 1 into a cylindrical mold that is customized according to the product design requirements. Use high-precision pressure equipment for pressing and molding. During the pressing process, the pressing density is accurately controlled at 2.5-3.5g / cm 3By precisely controlling the pressure and holding time, the cylindrical blank after forming is ensured to have appropriate density and shape stability, laying a good foundation for subsequent processes.

[0025] Step 3: Magnetization and orientation: Gently place the cylindrical product made in step 2 into a carefully designed rubber mold, and then place it in a special magnetizer. During the magnetization process, a high-intensity magnetic field of 3T-6T is applied to allow the NdFeB powder to achieve magnetization orientation under the action of the magnetic field, thereby initially forming a product structure with specific magnetic properties. This step places extremely high demands on the uniformity and stability of the magnetic field of the magnetizer. By optimizing the magnetic field design and control technology of the magnetizer, it is ensured that the product obtains uniform and consistent magnetic properties during the magnetization process.

[0026] Step 4: Secondary pressing: The magnetized and oriented product is pressed again using the cold isostatic pressing process. During the cold isostatic pressing process, the internal structure of the product is made denser by precisely controlling the pressure, holding time, and uniformity of pressure application, further improving the density and magnetic stability of the product, while eliminating the problem of uneven internal stress that may exist during the initial pressing process.

[0027] Step 5, sintering and tempering; carefully place the product pressed in step 4 into a vacuum sintering furnace. During the sintering process, the product is heated strictly according to the preset temperature rise curve to achieve densification sintering at high temperature. After sintering, tempering treatment is immediately carried out. By precisely controlling the tempering temperature and time, the organizational structure and magnetic properties of the product are adjusted, the residual stress generated during the sintering process is eliminated, and the toughness and comprehensive magnetic properties of the product are improved. After completing the sintering and tempering treatments, the product is taken out of the furnace and made into a blank column;

[0028] Step 6, surface treatment and magnetization detection: polish the surface of the blank column obtained in step 5, remove the oxide layer and uneven parts on the surface, so that the surface of the product meets the required smoothness requirements, and then put it into a multi-stage magnetizer for magnetization. After the magnetization is completed, the product is fully tested. Specific testing items include surface magnetic detection at all levels, using a high-precision Gauss meter to measure the surface magnetic field strength of each pole face of the product and record the data, and at the same time perform magnetic line distribution detection, using advanced magnetic line detection equipment to intuitively observe and analyze the distribution of the product's magnetic line of force, to ensure that the product's magnetic line of force is evenly distributed and the performance of each pole is consistent. Only products that pass strict testing can enter the subsequent packaging and application links.

[0029] Specific preparation case

[0030] S1. Powder preparation: Select 52M performance swing tablets, and use the airflow mill grinding process described in step 1 to grind them into powder with a particle size of 3.0um, and then put them into a stirring device and stir them evenly. The stirring time is 30 minutes and the stirring speed is 200 rpm.

[0031] S2. Initial pressing: According to the product design requirements, a cylindrical mold with a diameter of 9mm and a length of 30mm is selected, and the evenly mixed powder is loaded into the mold. According to the pressing process of step 2, the pressing pressure and holding time are accurately controlled to press into a cylindrical blank of D9*24 specification. When filling the powder, a vibration powder filling method is adopted. First, pre-press at a pressure of 5MPa for 10 seconds, and then the pressure is increased to 20MPa and held for 30 seconds to obtain a D9*24 cylinder.

[0032] S3. Forming and processing: After magnetizing orientation, cold isostatic pressing, sintering and tempering treatment in steps three to five, a D6.1*15 blank column is obtained. In step three, the magnetizing time is set to 5 seconds; in step four, the cold isostatic pressing pressure is 200MPa, and the holding time is 15 minutes; in step five, the vacuum sintering furnace is heated at a rate of 5°C / min, first heated to 800°C and kept warm for 2 hours, then continued to heat to 1100°C and kept warm for 3 hours, cooled to 600°C with the furnace, and then cooled to room temperature at a cooling rate of 3°C / min. The tempering temperature is 600°C and the holding time is 2 hours. During the whole process, the parameters of each process link are strictly monitored to ensure the stability and consistency of product quality.

[0033] S4, detection: After the surface of the blank column is polished according to step 6, it is placed in a multi-stage magnetizer for magnetization, and a magnetic pole piece is used to perform a preliminary detection of the magnetic pole distribution. By observing the degree of obviousness and uniformity of the magnetic pole distribution when the cylinder rotates one circle on the magnetic pole piece, an intuitive understanding of the magnetic pole distribution of the product can be obtained. At the same time, a Gauss meter is used to measure along the surface of the cylinder for one circle, and the change in the polarity of the product is recorded. It is found that the polarity of the product presents an NSNS distribution. The surface magnetic data of each pole face is further measured using a Gauss meter. It is found that the surface magnetic data of each pole face is very different, only 10 to 20 Gauss, which fully proves that the magnetic lines of force of the product produced by the preparation method of the present invention are evenly distributed, and the performance consistency of each pole is good.

[0034] Therefore, the present invention solves the problems of low material utilization rate and inability to achieve multi-pole magnetization mass production in the prior art in radial cylinder manufacturing through unique process steps and parameter control, and provides strong technical support for the development of NdFeB magnetic materials in high-end application fields.

[0035] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0036] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0037] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a multi-pole radial magnetization product, characterized in that: The specific steps include: Step 1: Powder preparation: Select the slices that meet the requirements, grind them into NdFeB powder by air jet mill, and stir the powder by stirring equipment to make it evenly mixed; Step 2: Initial pressing: The uniform powder prepared in step 1 is loaded into a cylindrical mold customized in advance according to product requirements, and pressed into shape using a high-precision pressure device; Step 3: Magnetization and orientation: The cylindrical product made in step 2 is gently loaded into a rubber mold, and then placed in a special magnetizer. During the magnetization process, a high-intensity magnetic field is applied to allow the NdFeB powder to achieve magnetization orientation under the action of the magnetic field, thereby initially forming a product structure with specific magnetic properties. Step 4: Secondary pressing: The magnetized and oriented product is pressed again by cold isostatic pressing; Step 5: sintering and tempering; The product pressed in step 4 is placed in a vacuum sintering furnace to achieve densification sintering. After sintering, it is tempered to eliminate the residual stress generated during the sintering process. After sintering and tempering, the product is taken out of the furnace to be made into a blank column; Step six, surface treatment and magnetization inspection; polish the surface of the blank column obtained in step five to remove the oxide layer and uneven parts on the surface, and then put it into a multi-stage magnetizer for magnetization. After the magnetization is completed, the product is fully inspected, and the products that pass the inspection are packaged.

2. The method for preparing a multi-pole radial magnetization product according to claim 1, characterized in that: In the step 1, the powder has a particle size of 1-6 um, and the stirring time is 20-50 minutes, and the stirring speed is 200 rpm.

3. The method for preparing a multi-pole radial magnetization product according to claim 1, characterized in that: The compaction density in step 2 is 2.5-3.5 g / cm 3 , and the pressure is 5-20MPa.

4. The method for preparing a multi-pole radial magnetization product according to claim 1, characterized in that: The magnetization time in step 3 is 2-10 seconds.

5. The method for preparing a multi-pole radial magnetized product according to claim 1, characterized in that: In the step 4, the cold isostatic pressing pressure is 200 MPa, and the holding time is 15 minutes.

6. The method for preparing a multi-pole radial magnetization product according to claim 1, characterized in that: The five empty sintering furnaces in the steps have a heating rate of 3-5°C / min, a temperature of 600-1100°C, and are kept warm for 2-3 hours.

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