TW202033936A - Method for measuring magnetic quantity of sintered NdFeB magnet products by using magnetic flux meter, balance and damagnetization coil - Google Patents

Abstract

The invention provides a magnetic measurement method for sintered NdFeB magnets, which can simplify the current measurement method, and is characterized in that the magnetic properties of the sintered NdFeB magnet products can be inspected according to the specifications by using a magnetic flux meter, a balance and a demagnetization coil. It can be applied to the final product of sintered NdFeB magnet with different shapes. The equipment for the measurement is cheap and the measured process is simple and fast.

Description

Magnetic measurement method of sintered NdFeB magnet

The invention relates to a magnetic detection method for sintered neodymium iron boron magnet products; more specifically, it particularly refers to a magnetic measurement method for sintered neodymium iron boron magnet products.

Sintered NdFeB magnets have been widely used in many fields such as electronic information, automobile industry, medical equipment, energy and transportation. At the same time, with the continuous progress of technology and the continuous decline of costs, neodymium iron boron permanent magnet materials have shown broad application prospects in many emerging fields. Especially under the general trend of low-carbon economy sweeping the world, countries all over the world are paying attention to environmental protection and low-carbon emissions as key scientific and technological fields. This puts forward new requirements for improving the energy structure, developing renewable energy, improving efficiency, energy saving and emission reduction, and promoting low-carbon life. It also provides for the development of low-carbon economic industries such as wind power generation, new energy vehicles, and energy-saving home appliances. Broad market space.

The magnetic measurement methods of conventional sintered NdFeB magnets are based on IEC 60404-5, JIS C2501 and GBT 3217-2013 standards. Standard magnetic measurement equipment is required for measurement, and the measurement samples are standardized, such as: (1 ) The shape must be a cylinder with a circular or rectangular cross-section. (2) The thickness of the test piece shall not be less than 5mm. (3) The size of the test piece shall not be larger than the diameter of the uniform magnetic field of the electromagnet pole tip used by the standard magnetic measurement equipment. (4) There are strict requirements on the tolerance of parallelism and perpendicularity of the test piece, and the roughness of the surface of the test piece.

The standard magnetic measurement equipment used in the conventional measurement method is expensive and the measurement sample Most of the products are measured by processing the semi-finished square blanks of sintered NdFeB magnets, and it is impossible to test the common final products of sintered NdFeB magnets, such as tile-shaped magnets and thin magnets (thickness less than 5mm).

In view of this, the present invention provides a magnetic measurement method for sintered NdFeB magnet products, which is characterized by using a flux meter, balance and demagnetization coil to test whether the magnetism of the sintered NdFeB magnet product meets the specifications. It can be applied to sintered NdFeB magnet products of different shapes. The equipment is cheap and the measurement method is simple and fast.

The main purpose of the present invention is to use a flux meter, balance and demagnetization coil to check whether the magnetic properties of sintered NdFeB magnet products meet specifications. The method can be applied to sintered NdFeB magnet products of different shapes, and the equipment is cheap and The measurement method is simple and fast.

According to the above-mentioned purpose, the magnetic measurement method of the sintered NdFeB magnet product of the present invention is as follows: (a) Sintered NdFeB magnet that meets the specifications of the brand of magnetic Br and magnetic energy product (BH) max Use a balance to measure the weight W; (b) Then the magnetic flux value M is measured by the magnetic flux meter, and the magnetic flux value M is divided by the magnet weight W measured in step a to obtain the magnetic Br and magnetic energy product (BH ) The magnetic value M/W of the max specification sintered NdFeB magnet; (c) The sintered NdFeB magnet of the same brand but unknown whether it meets the magnetic Br and magnetic energy product (BH)max specifications is measured in the above steps a and b , The weight W1 and the magnetic flux value M1 are respectively measured. If the measured magnetic value M1/W1 is greater than or equal to the magnetic value M/W obtained in step b, it is determined that the sintered NdFeB magnet meets the brand's magnetic Br and magnetic energy product (BH )max specification, on the contrary, if the measured magnetic value M1/W1 is less than the magnetic value M/W obtained in step b, it is determined that the sintered NdFeB magnet does not meet the brand's magnetic Br and magnetic energy product (BH) max specifications; (d) The magnetic flux value M2 of the sintered NdFeB magnet that is known to meet the magnetic coercivity (iHc) specifications of the brand is measured with a magnetic flux meter; (e) Next, demagnetize the magnets with demagnetization coils from small to large to generate a reverse magnetic field to demagnetize the sintered NdFeB magnet; (f) After each demagnetization, use a magnetic flux meter to measure the magnetic flux value of the magnet, and record the demagnetization The demagnetization field H required for the magnetic flux value of the magnet to decline by 10%; (g) The sintered neodymium iron boron magnet of the same shape and the same grade but not known whether it meets the magnetic coercivity (iHc) specifications is measured with a magnetic flux meter to obtain the magnetic flux value M3, and then After the magnet is demagnetized by the demagnetizing field H obtained in step f, the magnetic flux value M4 is measured by the magnetic flux meter. The measured M4 is compared with M3. If the flux decline is less than or equal to 10%, the sintered NdFeB magnet is determined It meets the magnetic coercivity (iHc) specifications of the brand. On the contrary, if the flux decline is greater than 10%, it is determined that the sintered NdFeB magnet does not meet the magnetic coercivity (iHc) specifications of the brand; and (h) different shapes are the same If a grade of sintered NdFeB magnet is judged whether it meets the magnetic coercivity (iHc) specifications of the grade, it needs to go through the aforementioned steps d to f.

The magnetic energy product (BH) max of the sintered neodymium iron boron magnet can be 30-55 (MGOe), and the coercive force iHc can be 10-40 (kOe).

The magnetic flux value M of the sintered neodymium iron boron measured by the use of a magnetic flux meter can be a moment, a flux, or a magnetic flux (intergrator).

The magnetic field that the demagnetization coil can generate is 0.1-4 (T).

The shape of the sintered NdFeB magnet can be a cylinder, a disc shape or a tile shape.

When the shape of the sintered NdFeB magnet is a cylinder, the diameter is 15-20 mm and the thickness is 8-10 mm.

When the shape of the sintered NdFeB magnet is a round cake shape, the diameter is 15-20 mm and the thickness is 4-5 mm.

When the shape of the sintered NdFeB magnet is tile shape, the outer diameter is 24-25mm, the inner diameter is 22-23mm, the length is 23-25mm, the width is 10-11mm, and the thickness is 1-2mm.

The thickness of the sintered neodymium iron boron magnet is 10 mm or less.

The magnetic measurement method of another sintered NdFeB magnet product of the present invention is as follows: (a) Use a balance to measure the sintered NdFeB magnet that is known to meet the specifications of the brand's magnetic Br and magnetic energy product (BH) max Measure the weight W; (b) Then the magnetic flux value M is measured by the magnet with a magnetic flux meter, and the magnetic flux value M is divided by the magnet weight W measured in step a to obtain the magnetic Br and magnetic energy product (BH) max specifications that meet the brand The magnetic value M/W of the sintered NdFeB magnet; (c) The sintered NdFeB magnet of the same brand but unknown whether it meets the magnetic Br and magnetic energy product (BH)max specifications is measured in the above steps a and b, respectively. Obtain the weight W1 and the magnetic flux value M1. If the measured magnetic value M1/W1 is greater than or equal to the magnetic value M/W obtained in step b, it is determined that the sintered NdFeB magnet meets the magnetic Br and magnetic energy product (BH) max specifications of the brand On the contrary, if the measured magnetic value M1/W1 is less than the magnetic value M/W obtained in step b, it is determined that the sintered NdFeB magnet does not meet the specifications of the brand's magnetic Br and magnetic energy product (BH) max; (d) will be known The magnetic flux value M2 of the sintered NdFeB magnet that meets the magnetic coercivity (iHc) specifications of the brand is measured by a magnetic flux meter; (e) Then the magnet is used to demagnetize the coil to generate a reverse magnetic field from small to large one by one to sinter the NdFeB magnet Perform demagnetization; (f) After each demagnetization, use a magnetic flux meter to measure the magnetic flux value of the magnet, and record the demagnetization field H required for the magnet flux value to decline by 10% after demagnetization; (g) The same shape and the same brand but unknown Whether the sintered neodymium iron boron magnet that meets the magnetic coercivity (iHc) specifications is measured with a magnetic flux meter, the magnetic flux value M3 is measured, and then the magnet is demagnetized by the demagnetizing field H obtained in step f, and then the magnetic flux value M4 is measured by the magnetic flux meter. Comparing the measured M4 with M3, if the flux decay is less than or equal to 10%, it is judged that the sintered NdFeB magnet meets the magnetic coercivity (iHc) specification of the brand, on the contrary, if the flux decay is greater than 10%, it is judged The sintered NdFeB magnet The stone does not meet the magnetic coercivity (iHc) specifications of the brand; and (h) If sintered NdFeB magnets of different shapes and the same brand are judged to meet the magnetic coercivity (iHc) specifications of the brand, the aforementioned steps d to f The shape of the sintered NdFeB magnet can be a cylinder, a disc or a tile shape; the thickness of the sintered NdFeB magnet is less than 5mm.

In order to have a more detailed understanding of the purpose, efficacy, features, and structure of the present invention, preferred embodiments are described below in conjunction with the drawings.

A‧‧‧Cylinder

B‧‧‧Pie Shape

C‧‧‧tile shape

Step a~h‧‧‧Sintered NdFeB magnet magnetic measurement method steps

Figure 1: The flow chart of the magnetic measurement method of the sintered NdFeB magnet of the present invention; Figure 2: The schematic diagram of the sintered NdFeB magnet of the present invention.

Figure 1 is a flow chart of the magnetic measurement method of the sintered NdFeB magnet of the present invention. Please refer to Figure 1; Figure 1 shows that the magnetic measurement method of a sintered NdFeB magnet of the present invention is as follows: (a) The magnetic Br and magnetic energy product (BH) max specifications of the brand are known to be met Use a balance to measure the weight W of the sintered neodymium iron boron magnet; (b) Then the magnetic flux value M is measured by the magnetic flux meter, and the magnetic flux value M is divided by the magnet weight W measured in step a to obtain the magnetism conforming to the grade Magnetic value M/W of sintered NdFeB magnet with Br and magnetic energy product (BH)max specifications; (c) Perform the above steps on sintered NdFeB magnets of the same brand but unknown whether they meet the magnetic Br and magnetic energy product (BH)max specifications For the measurement of a and b, the weight W1 and the magnetic flux value M1 are respectively measured. If the measured magnetic value M1/W1 is greater than or equal to the magnetic value M/W obtained in step b, it is determined that the sintered NdFeB magnet conforms to the grade of magnetism Br and magnetic energy product (BH) max specifications, on the contrary, if the measured magnetic value M1/W1 is less than the magnetic value M/W obtained in step b, it is determined that the sintered NdFeB magnet does not meet the brand's magnetic Br and magnetic energy product (BH) max specification; (d) The magnetic flux value M2 of the sintered neodymium iron boron magnet that is known to meet the magnetic coercivity (iHc) specifications of the brand is measured with a magnetic flux meter; (e) The magnet is then used to demagnetize coils to generate a reverse magnetic field from small to large. Demagnetize the sintered neodymium iron boron magnet; (f) After each demagnetization, use the magnetic flux meter to measure the magnetic flux value of the magnet, and record the demagnetization magnetic field H required for the magnet flux value to decline by 10% after demagnetization; (g) Sintered neodymium iron boron magnets of the same shape and the same grade but unknown whether they meet the magnetic coercivity (iHc) specifications are measured with a magnetic flux meter to measure the magnetic flux value M3, and then the magnet is demagnetized with the demagnetizing field H obtained in step f, and then measured with a magnetic flux meter Obtain the magnetic flux value M4, compare the measured M4 with M3, if the magnetic flux decline is less than or equal to 10%, it is determined that the sintered neodymium iron boron magnet meets the magnetic coercivity (iHc) specifications of the brand, otherwise, if the magnetic flux declines If it is greater than 10%, it is judged that the sintered NdFeB magnet does not meet the magnetic coercivity (iHc) specification of the brand; and (h) If the sintered NdFeB magnet of the same brand of different shape is judged to meet the magnetic coercivity (iHc) of the brand ) Specifications, you need to go through the aforementioned steps d to f.

Figure 2 is a schematic diagram of the sintered NdFeB magnet of the present invention. Please continue to refer to Figures 1 and 2; in the first embodiment of the present invention, (I) magnetic Br, (BH)max and iHc meet N50H specifications, (II) magnetic Br and (BH)max are higher than N50H specifications And the iHc is lower than the N50H specification, and (III) the magnetic iHc is higher than the N50H specification and the Br and (BH)max are lower than the N50H specification. The sintered neodymium iron boron magnet blank is processed into cylinder A, disc shape B and tile shape respectively C, as shown in Figure 2, the dimensions are cylinder A: diameter 20mm, thickness 9.1mm; round cake shape B: diameter 20mm, thickness 4.3mm; tile shape C: outer R 25mm, inner R 23mm, length 25mm, The width is 11mm and the thickness is 2mm. The magnetic measurement of the product is carried out using the conventional measurement method and the magnetic measurement method of the sintered NdFeB magnet provided by the present invention. The measured magnetic values are listed in Table 1.

From the comparison results in Table 1, it can be found that the conventional magnetic measurement method of sintered NdFeB magnet can only measure the standard shape cylindrical A sample with a thickness greater than 5mm. For the thinner round cake-shaped sample B and tile-shaped sample C, It cannot be measured, and the magnetic test can only be carried out by using the magnetic measurement method of the sintered NdFeB magnet provided by the present invention.

Using the conventional magnetic measurement method to measure the cylinder A sample, it can be found that the magnetic Br, (BH)max and iHc of sample IA meet the N50H specification, and the magnetic Br and (BH)max of sample II-A are higher than the N50H specification and iHc The magnetic iHc of sample III-A is lower than the N50H specification, and the magnetic iHc of the sample III-A is higher than the N50H specification and Br and (BH)max are lower than the N50H specification. Using the measurement method provided by the present invention, the magnetic Br and (BH)max specification inspection , The magnetic M/W of sample IA conforming to N50H specification is 116 * 10 ^-5 (Vs/g), and the magnetic value of sample II-A is measured to be 116.39* 10 ^-5 (Vs/g) greater than 116 * 10 ^-of sample IA ⁵ (Vs/g), it can be determined that the magnetic Br and (BH)max meet the N50H specification. The magnetic M/W of sample III-A is measured to be 115.12* 10 ^-5 (Vs/g) less than 116* 10 ^-of sample IA ⁵ (Vs/g), it can be determined that the magnetic Br and (BH)max do not meet the N50H specification, and the result is the same as the conventional measurement method; in the specification inspection of the magnetic iHc, the IA flux decline of the sample that meets the N50H specification is measured The demagnetizing field required for 10% is 8.88 (kG). After demagnetizing sample II-A with this demagnetizing field, the flux decay is greater than 10%. It can be determined that the magnetic iHc does not meet the N50H specification. After demagnetization, the flux decay is less than 10%, it can be determined that the magnetic iHc meets the N50H specification, and the result is the same as the conventional measurement method.

Because the thickness of the disc-shaped B sample is less than 5mm, the conventional measurement method cannot measure it. With the measurement method provided by the present invention, in the specification inspection of magnetic Br and (BH)max, the magnetic properties of II-B can be found If M/W is greater than IB, it can be determined that the magnetic Br and (BH)max magnetism meets the N50H specification. The magnetic M/W of sample III-B is less than IB, so it can be determined that the magnetic Br and (BH)max magnetism does not meet the N50H specification. The measurement results of sample A are the same; in terms of iHc specification inspection, it is measured that the demagnetizing field required for 10% flux decay of sample II-B conforming to the N50H specification is 7.05 (kG), which demagnetizes sample II-B After demagnetization, the magnetic flux decay is greater than 10%, so it can be judged that the magnetic iHc magnetism does not meet the N50H specification. After this demagnetization field demagnetizes the sample III-B, the magnetic flux decay is less than 10%, and it can be judged that the magnetic iHc magnetism conforms to the N50H specification. The measurement results of the cylinder A sample are the same.

Because the tile-shaped C sample is not the standard rectangle or circle required by the conventional measurement method, it cannot be measured. With the measurement method provided by the present invention, in the specification inspection of magnetic Br and (BH)max, It can be found that the magnetic M/W of II-C is greater than IC, and it can be determined that the magnetic Br and (BH)max are in compliance with the N50H specification. The magnetic M/W of sample III-C is less than IC, and it can be determined that the magnetic Br and (BH)max are not Comply with N50H specification, the result is the same as the measurement results of sample A and sample B; in the specification inspection of magnetic iHc, the demagnetizing field required to measure 10% flux decline of sample II-C that meets N50H specification is 6.02(kG) After this demagnetization field demagnetizes sample II-C, the magnetic flux decay is greater than 10%, and it can be judged that the magnetic iHc does not meet the N50H specification. After demagnetizing sample III-C, the magnetic flux decay is less than 10%, which can be judged The magnetic iHc conforms to the N50H specification, and the results are the same as the measurement results of the cylinder A sample and the disc B sample.

According to the results in Table 1, it is found that in the measurement method provided by the present invention, the magnetic value M/W will not change with the shape of the test piece, and the demagnetizing field H will vary with the shape of the test piece. It's different.

Please continue to refer to Figures 1 and 2; in the second embodiment of the present invention, (IV) magnetic Br, (BH)max and iHc meet N42SH specifications, and (V) magnetic Br and (BH)max are higher than N42SH specifications And the iHc is lower than the N42SH specification, and (VI) the magnetic iHc is higher than the N42SH specification and the Br and (BH)max are lower than the N42SH specification. The sintered neodymium iron boron magnet blank is processed into cylinder A, disc shape B and tile shape respectively C. The size and shape are the same as in [Example 1], as shown in Figure 2, respectively, using the conventional measurement method and the magnetic measurement method of the sintered NdFeB magnet provided by the present invention to measure and inspect the magnetic properties of the product. The magnetic values are listed in Table 2.

From the comparison results in Table 2, it can be found that the conventional magnetic measurement method of sintered NdFeB magnet can only measure the standard shape cylindrical A sample with a thickness greater than 5mm. For the thinner disc-shaped B sample and tile-shaped C sample It cannot be measured, and the magnetic test can only be carried out by using the magnetic measurement method of the sintered NdFeB magnet provided by the present invention.

Using the conventional magnetic measurement method to measure the cylinder A sample, it can be found that the magnetic Br, (BH)max and iHc of sample IV-A meet the N42SH specification, and the magnetic Br and (BH)max of the sample VA are higher than the N42SH specification. iHc is lower than the N42SH specification, and the magnetic iHc of the sample VI-A is higher than the N42SH specification and Br and (BH)max are lower than the N42SH specification. The measurement method provided by the present invention is used in the inspection of Br and (BH)max specifications , The magnetic M/W of sample IV-A conforming to N42SH specification is 107.1*10 ^-5 (Vs/g), and the magnetic M/W of sample VA is measured to be 109.3*10 ^-5 (Vs/g) greater than IV-A 107.1*10 ^-5 (Vs/g), it can be judged that the magnetic Br and (BH)max magnetism meet the N42SH specification. The magnetic M/W of sample VI-A is measured to be 105.84*10 ^-5 (Vs/g) less than IV- A of 107.1*10 ^-5 (Vs/g), it can be judged that the magnetic Br and (BH)max magnetism do not meet the N42SH specification, and the result is the same as the conventional measurement method; in terms of the iHc specification inspection, the measurement is consistent with N42SH The demagnetizing field required for the specification sample IV-A to demagnetize the magnetic flux by 10% is 13.78 (kG). After this demagnetizing field demagnetizes the sample VA, the flux degeneration is greater than 10%. It can be determined that the magnetic iHc does not meet the N42SH specification. After the sample VI-A is demagnetized, the magnetic flux decay is less than 10%, so it can be determined that the magnetic iHc conforms to the N42SH specification, and the result is the same as the conventional measurement method.

Because the thickness of the disc-shaped B sample is less than 5mm, the conventional measurement method cannot measure it. With the measurement method provided by the present invention, in the specification inspection of magnetic Br and (BH)max, it can be found that the magnetic M/ of VB If W is greater than IV-B, it can be judged that the magnetic Br and (BH)max magnetism meets the N42SH specification, and the magnetic M/W of sample VI-B is less than IV-B, and it can be judged that the magnetic Br and (BH)max magnetism does not conform to the N42SH specification. The measurement result is the same as that of the cylinder A sample; in the iHc specification inspection, it is measured that the demagnetizing field required for the IV-B flux decay 10% of the N42SH specification sample is 11.25 (kG), and the sample is demagnetized After VB demagnetization, the magnetic flux decay is greater than 10%, it can be judged that the magnetic iHc magnetic does not meet the N42SH specification. After the sample VI-B is demagnetized by the demagnetization, the magnetic flux decay is less than 10%, so it can be judged that the magnetic iHc magnetism conforms to the N42SH specification. The result is the same as the measurement result of the cylinder A sample.

Because the tile-shaped C sample is not the standard rectangle or circle required by the conventional measurement method, it cannot be measured. With the measurement method provided by the present invention, in terms of Br and (BH)max specification inspection, it can be It is found that the magnetic M/W of VC is greater than IV-C, and the magnetic Br and (BH)max magnetism conforms to N42SH specification, the magnetic M/W of sample VI-C is less than IV-C, it can be judged that the magnetic Br and (BH)max magnetism do not conform to N42SH specification, the result is similar to the cylinder A sample and the disc B sample The measurement results are the same; in the iHc specification inspection, it is measured that the demagnetizing field required for the IV-C flux decay of 10% of the N42SH specification sample is 9.70 (kG). After the demagnetizing field demagnetizes the sample VC, the magnetic If the flux decay is greater than 10%, it can be determined that the magnetic iHc does not meet the N42SH specification. After the sample VI-C is demagnetized by the demagnetization field, the magnetic flux decay is less than 10%, and the magnetic iHc magnetism can be determined to comply with the N42SH specification. The measurement result is the same as that of the round cake B sample.

According to the results in Table 2, it is found that in the measurement method provided by the present invention, the magnetic value M/W will not change with the shape of the test piece, and the demagnetizing field will vary with the shape of the test piece. The results were the same as [Example 1].

Please continue to refer to Figures 1 and 2; in the third embodiment of the present invention, (VII) magnetic Br, (BH)max and iHc meet N38UH specifications, and (VIII) magnetic Br and (BH)max are higher than N38UH specifications And iHc is lower than N42SH specification, and (IX) magnetic iHc is higher than N38UH specification and Br and (BH)max are lower than N38UH specification sintered neodymium iron boron magnet blanks are processed into cylinder A, disc shape B and tile shape respectively C. The size and shape are the same as in [Example 1], as shown in Figure 2, respectively, using the conventional measurement method and the magnetic measurement method of the sintered NdFeB magnet provided by the present invention to measure and inspect the magnetic properties of the product. The magnetic values are listed in Table 3.

From the comparison results in Table 3, it can be found that the conventional sintered NdFeB magnet magnetic measurement method can only measure the standard shape cylindrical A sample with a thickness greater than 5mm. For the thinner disc-shaped sample B and tile-shaped sample C It cannot be measured, and the magnetic test can only be carried out by using the magnetic measurement method of the sintered NdFeB magnet provided by the present invention.

Using the conventional magnetic measurement method to measure the sample of cylinder A, it can be found that the magnetic Br, (BH)max and iHc of sample VII-A meet the N38UH specification, and the magnetic Br and (BH)max of sample VIII-A are higher than N38UH Specification and iHc is lower than N38UH specification, and the magnetic iHc of sample IX-A is higher than N38UH specification and Br and (BH)max are lower than N38UH specification, using the measurement method provided by the present invention, in magnetic Br and (BH)max In terms of specification inspection, the magnetic M/W of sample VII-A that meets the N38UH specification is 101.4*10 ^-5 (Vs/g), and the magnetic M/W of sample VIII-A is measured to be 102.92* 10 ^-5 (Vs/g) ) Is greater than 101.4*10 ^-5 (Vs/g) of VII-A, it can be determined that the magnetic Br and (BH)max meet the N38UH specification. The magnetic M/W of sample IX-A is measured to be 100.12* 10 ^-5 (Vs/ g) Less than 101.4*10 ^-5 (Vs/g) of VII-A, it can be determined that the magnetic Br and (BH)max do not meet the N38UH specification, and the result is the same as the conventional measurement method; in terms of the iHc specification inspection, the measurement It is determined that the demagnetizing field required for the magnetic flux decay of sample VII-A of N38UH specification by 10% is 18.05 (kG). After the demagnetization of sample VIII-A by this demagnetizing field, the flux decay is greater than 10%. It conforms to the N38UH specification. After the sample XI-A is demagnetized with this demagnetization field, the flux decline is less than 10%. It can be determined that the magnetic iHc conforms to the N38UH specification. The result is the same as the conventional measurement method.

Because the thickness of the disc-shaped B sample is less than 5mm, the conventional measurement method cannot be measured. With the measurement method provided by the present invention, in the specification inspection of magnetic Br and (BH)max, sample VIII-B can be found If the magnetic M/W is greater than VII-B, it can be determined that the magnetic Br and (BH)max meet the N38UH specification. The magnetic M/W of sample IX-B is less than VII-B, and it can be determined that the magnetic Br and (BH)max do not meet the N38UH specification. , The result is the same as the measurement result of the cylinder A sample; in the magnetic iHc specification inspection, it is measured that the demagnetizing field required for the sample VII-B conforming to the N38UH specification for 10% flux decline is 15.43 (kG). After the magnetic field demagnetizes sample VIII-B, the magnetic flux decays greatly At 10%, it can be determined that the magnetic iHc does not meet the N38UH specification. After the sample IX-B is demagnetized by the demagnetization field, the magnetic flux decline is less than 10%, so it can be determined that the magnetic iHc meets the N38UH specification. The result is the same as the measurement of the cylinder A sample The result is the same.

Because the tile-shaped C sample is not the standard rectangle or circle required by the conventional measurement method, it cannot be measured. With the measurement method provided by the present invention, in the specification inspection of magnetic Br and (BH)max, It can be found that the magnetic M/W of sample VIII-C is greater than VII-C, and it can be determined that the magnetic Br and (BH)max meet the N38UH specification. The magnetic of sample IX-C is less than VII-C, and it can be determined that the magnetic Br and (BH)max are not Conforms to N38UH specifications, and the results are the same as the measurement results of cylinder A samples and round cake B samples; in the specification inspection of magnetic iHc, the demagnetizing field required for the VII-C sample VII-C to meet N38UH specifications is measured It is 13.84 (kG). After the sample VIII-C is demagnetized by the demagnetization field, the magnetic flux decay is greater than 10%. It can be determined that the magnetic iHc does not meet the N38UH specification. After the sample IX-C is demagnetized by the demagnetization field, the flux decay is less than 10%, it can be determined that the magnetic iHc meets the N38UH specification, and the results are the same as the measurement results of the cylinder A sample and the round cake B sample.

According to the results in Table 3, it is found that in the measurement method provided by the present invention, the magnetic value M/W will not change with the shape of the test piece, and the demagnetizing field will vary with the shape of the test piece. The results are the same as [Example 1] and [Example 2].

The magnetic measurement method of another sintered NdFeB magnet of the present invention is as follows: (a) Use a balance to measure the weight of a sintered NdFeB magnet that is known to meet the specifications of the brand's magnetic Br and magnetic energy product (BH)max W; (b) Then the magnetic flux value M is measured by the magnet with a magnetic flux meter, and the magnetic flux value M is divided by the magnet weight W measured in step a to obtain the sintered neodymium that meets the specifications of magnetic Br and magnetic energy product (BH)max The magnetic value M/W of the iron boron magnet; (c) The sintered neodymium iron boron magnet of the same brand but unknown whether it meets the magnetic Br and magnetic energy product (BH) max specifications is measured in the above steps a and b, and the weight is measured respectively W1 and magnetic flux value M1, If the measured magnetic value M1/W1 is greater than or equal to the magnetic value M/W obtained in step b, it is determined that the sintered neodymium iron boron magnet meets the brand's magnetic Br and magnetic energy product (BH) max specifications. On the contrary, if the magnetic value M1 is measured /W1 is less than the magnetic value M/W obtained in step b, then it is determined that the sintered NdFeB magnet does not meet the specifications of the brand's magnetic Br and magnetic energy product (BH) max; (d) The known magnetic coercivity (iHc) ) The magnetic flux value M2 of the sintered NdFeB magnet of specifications is measured with a magnetic flux meter; (e) Then the magnet is used to demagnetize the coil to generate a reverse magnetic field from small to large to demagnetize the sintered NdFeB magnet; (f) every time After demagnetization, use the magnetic flux measurement to measure the magnetic flux value of the magnet, and record the demagnetization field H required for the magnet flux value to decline by 10% after demagnetization; (g) The same shape and the same brand but it is unknown whether it meets the magnetic coercivity (iHc) The magnetic flux value M3 of the sintered neodymium iron boron magnet of specifications is measured by the magnetic flux meter, and then the magnet is demagnetized by the demagnetizing field H obtained in step f, and then the magnetic flux value M4 is measured by the magnetic flux meter. The measured M4 is compared with M3. If the flux decay is less than or equal to 10%, it is determined that the sintered NdFeB magnet meets the magnetic coercivity (iHc) specifications of the brand. On the contrary, if the flux decay is greater than 10%, it is determined that the sintered NdFeB magnet does not meet the Grade magnetic coercivity (iHc) specifications; and (h) If sintered neodymium iron boron magnets of different shapes and the same grade are judged to meet the magnetic coercivity (iHc) specifications of the brand, the aforementioned steps d to f are required; The shape of the NdFeB magnet can be a cylinder, a round cake or a tile shape; the thickness of the sintered NdFeB magnet is less than 5mm.

Therefore, the present invention has excellent advancement and practicability among similar products. At the same time, after searching through domestic and foreign technical documents about this type, it is true that no identical or similar structure or technology exists before the application of this case. This case should have met the patent requirements of "inventiveness", "applicability for industrial use" and "progressiveness", and an application was filed in accordance with the law.

However, the above-mentioned are only the preferred embodiments of the present invention. Any other equivalent structural changes made in the specification of the present invention and the scope of the patent application should be included in this The invention is within the scope of patent application.

Step a~h‧‧‧Sintered NdFeB magnet magnetic measurement method steps

Claims (10)

A sintered neodymium iron boron magnet magnetic measurement method, the measurement method is as follows: (a) The sintered neodymium iron boron magnet known to meet the specifications of the brand's magnetic Br and magnetic energy product (BH) max is used to measure the weight W with a balance; b) Then the magnetic flux value M is measured by the magnet with a magnetic flux meter, and the magnetic flux value M is divided by the magnet weight W measured in step a to obtain a sintered NdFeB magnet that meets the specifications of magnetic Br and magnetic energy product (BH) max The magnetic value M/W; (c) The sintered neodymium iron boron magnet of the same brand but unknown whether it meets the magnetic Br and magnetic energy product (BH) max specifications is measured in the above steps a and b, and the weight W1 and magnetic are measured respectively If the measured magnetic value M1/W1 is greater than or equal to the magnetic value M/W obtained in step b, it is determined that the sintered neodymium iron boron magnet meets the specifications of magnetic Br and magnetic energy product (BH) max of the brand, and vice versa. If the measured magnetic value M1/W1 is less than the magnetic value M/W obtained in step b, it is determined that the sintered NdFeB magnet does not meet the specifications of the brand's magnetic Br and magnetic energy product (BH) max; (d) The known magnetic correction The magnetic flux value M2 of the sintered NdFeB magnet with coercivity (iHc) specification is measured by the magnetic flux meter; (e) Then the magnet is used to demagnetize the coil from small to large to generate a reverse magnetic field to demagnetize the sintered NdFeB magnet; (f) ) After each demagnetization, use the magnetic flux meter to measure the magnetic flux value of the magnet, and record the demagnetization magnetic field H required for the magnet flux value to decline by 10% after demagnetization; (g) The same shape and the same grade but it is unknown whether it meets the magnetic coercivity The magnetic flux value M3 of the sintered neodymium iron boron magnet with force (iHc) specification is measured by a magnetic flux meter, and then the magnet is demagnetized by the demagnetizing field H obtained in step f, and then the magnetic flux value M4 is measured by the magnetic flux meter. M3 In comparison, if the flux decay is less than or equal to 10%, it is determined that the sintered NdFeB magnet meets the magnetic coercivity (iHc) specifications of the brand. On the contrary, if the flux decay is greater than 10%, the sintered NdFeB magnet is determined Does not meet the magnetic coercivity (iHc) specifications of the brand; and (h) If sintered neodymium iron boron magnets of the same brand with different shapes are judged to meet the magnetic coercivity (iHc) specifications of the brand, the aforementioned steps d to f are required. The magnetic measurement method of sintered NdFeB magnet as described in claim 1, wherein the energy product (BH)max of the sintered NdFeB magnet can be 30~55(MGOe), and the coercivity iHc can be 10~40 (kOe). The magnetic measurement method of the sintered NdFeB magnet according to claim 1, wherein the magnetic flux value M of the sintered NdFeB magnet measured by the magnetic flux meter can be a moment, a flux, or a magnetic flux (intergrator). ). The magnetic measurement method of the sintered NdFeB magnet according to claim 1, wherein the magnetic field generated by the demagnetization coil is 0.1-4 (T). The magnetic measurement method of the sintered NdFeB magnet according to claim 1, wherein the shape of the sintered NdFeB magnet can be a cylinder, a disc or a tile shape. The magnetic measurement method of a sintered NdFeB magnet according to claim 5, wherein, when the sintered NdFeB magnet is cylindrical, the diameter is 15-20mm and the thickness is 8-10mm. The magnetic measurement method of the sintered NdFeB magnet according to claim 5, wherein when the sintered NdFeB magnet is in the shape of a disc, the diameter is 15-20mm and the thickness is 4-5mm. The magnetic measurement method of the sintered NdFeB magnet described in claim 5, wherein, when the sintered NdFeB magnet is tile-shaped, the outer diameter is 24-25mm, the inner diameter is 22-23mm, and the length is 23~ 25mm, width 10~11mm, thickness 1~2mm. The magnetic measurement method of the sintered NdFeB magnet according to claim 1, wherein the sintered NdFeB magnet The thickness of the magnet is 10mm or less. A sintered neodymium iron boron magnet magnetic measurement method, the measurement method is as follows: (a) The sintered neodymium iron boron magnet known to meet the specifications of the brand's magnetic Br and magnetic energy product (BH) max is used to measure the weight W with a balance; b) Then the magnetic flux value M is measured by the magnet with a magnetic flux meter, and the magnetic flux value M is divided by the magnet weight W measured in step a to obtain a sintered NdFeB magnet that meets the specifications of magnetic Br and magnetic energy product (BH) max The magnetic value M/W; (c) The sintered neodymium iron boron magnet of the same brand but unknown whether it meets the magnetic Br and magnetic energy product (BH) max specifications is measured in the above steps a and b, and the weight W1 and magnetic are measured respectively If the measured magnetic value M1/W1 is greater than or equal to the magnetic value M/W obtained in step b, it is determined that the sintered neodymium iron boron magnet meets the specifications of magnetic Br and magnetic energy product (BH) max of the brand, and vice versa. If the measured magnetic value M1/W1 is less than the magnetic value M/W obtained in step b, it is determined that the sintered NdFeB magnet does not meet the specifications of the brand's magnetic Br and magnetic energy product (BH) max; (d) The known magnetic correction The magnetic flux value M2 of the sintered NdFeB magnet with coercivity (iHc) specification is measured by the magnetic flux meter; (e) Then the magnet is used to demagnetize the coil from small to large to generate a reverse magnetic field to demagnetize the sintered NdFeB magnet; (f) ) After each demagnetization, use the magnetic flux meter to measure the magnetic flux value of the magnet, and record the demagnetization magnetic field H required for the magnet flux value to decline by 10% after demagnetization; (g) The same shape and the same grade but it is unknown whether it meets the magnetic coercivity The magnetic flux value M3 of the sintered neodymium iron boron magnet with force (iHc) specification is measured by a magnetic flux meter, and then the magnet is demagnetized by the demagnetizing field H obtained in step f, and then the magnetic flux value M4 is measured by the magnetic flux meter. M3 In comparison, if the flux decay is less than or equal to 10%, it is determined that the sintered NdFeB magnet meets the magnetic coercivity (iHc) specifications of the brand. On the contrary, if the flux decay is greater than 10%, the sintered NdFeB magnet is determined Does not meet the magnetic coercivity (iHc) specifications of the brand; and (h) If sintered neodymium iron boron magnets of different shapes and the same brand are determined to meet the magnetic coercivity (iHc) specifications of the brand, the aforementioned steps d to f are required; The shape of the sintered neodymium iron boron magnet can be a cylinder, a disc shape or a tile shape; the thickness of the sintered neodymium iron boron magnet is less than 5 mm.

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