CN114460511A - A kind of finished magnetic steel performance testing method - Google Patents

Abstract

The invention discloses a method for testing the performance of a finished magnetic steel. The magnetic moment value M1 of the magnetic steel is tested; the magnetic steel is fixed in a demagnetization device and a first demagnetizing field is applied; Test the magnetic moment value M2 to determine whether the secondary magnetic moment value satisfies the adjustment; until the magnetic moment value is satisfied, record the demagnetizing field value at this time; the knee point coercivity value Hk required for detection is between Hi-1 and Hi. Continue to apply the second demagnetization field in the fixed demagnetization equipment of the magnetic steel; take out the magnetic steel, and then measure the third magnetic moment value of the magnetic steel; calculate and judge whether the secondary magnetic moment value meets the conditions; The demagnetizing field value Hj; the lowest intrinsic coercivity value Hcj is between Hj‑1 and Hj. Under the premise of not destroying the magnetic steel, the finished magnetic steel of the same industry can be directly detected and analyzed. The detection and testing speed is fast, the detection efficiency is high, and the detection accuracy is high.

Description

A method for testing the performance of finished magnetic steel

technical field

The invention relates to a magnetic steel detection, in particular to a magnetic steel performance testing method used for testing the magnetic steel performance.

Background technique

Usually there are three most important parameters in the magnetic properties of magnetic steel, the first is remanence (Br), the second is intrinsic coercivity (Hcj), and the third is knee coercivity (Hk); among which Br is the strength of the magnetic field that can be generated by the magnetic steel, Hcj is the magnetic field required when the magnetic steel is completely demagnetized, and Hk is the magnetic field strength when the magnetic steel begins to demagnetize. In actual use, the significance of Hk is even greater.

There are two ways to evaluate the performance of the existing magnetic steel: 1. Cut the standard sample block from the blank and grind its surface, and then use the hysteresis loop tester to measure the performance of the magnetic steel; the standard sample block The size of the magnet is usually D10*10mm cylinder or 10*10*10mm square. In order to use the corresponding test coil, the size of the magnetization direction of the magnet should generally not be less than 5mm; 2. Test the magnetic field strength on the surface of the magnet to calculate the residual material Magnetic (Br), test the demagnetization ratio of the magnetic steel at different temperatures to calculate the intrinsic coercivity value (Hcj).

However, in the actual production or research and development process, it is often necessary to benchmark the products of the same industry, and it is necessary to obtain the most accurate performance in the fastest time without damaging the magnetic steel. In the existing method of the prior art 1 among the above-mentioned evaluation test methods, it is necessary to make a standard sample block, grind the surface thereof, and then use the corresponding test coil in conjunction with the hysteresis loop tester to obtain accurate results; And there are restrictions on the size of the detected magnetic steel, which cannot meet the above-mentioned non-destructive testing conditions on the premise of not damaging the magnetic steel, and cannot directly test the finished magnetic steel; and the prior art 2 test in the above-mentioned evaluation test method exists. The demagnetization ratio at different temperatures takes a long time, and the error is large. There is a calculation of the Br and Hcj values through the surface magnetic field and the demagnetization ratio, and the accuracy is not high.

SUMMARY OF THE INVENTION

The present invention solves the problem that the existing magnetic steel performance testing method cannot meet the need for benchmark detection and analysis of products in the same industry in the existing actual production or research and development process, and needs to be tested on the premise of not damaging the magnetic steel. The magnetic steel performance detection accuracy is not high and the current situation provides a method that can directly detect and analyze the finished magnetic steel products of the same industry without destroying the magnetic steel. The detection and testing speed is fast, the detection efficiency is high, and the detection is accurate. High-quality finished magnetic steel performance test method.

The specific technical scheme adopted by the present invention to solve the above-mentioned technical problems is: a method for testing the performance of finished magnetic steel, which is characterized in that it comprises the following testing steps:

A1. Test the M1 magnetic moment value of the magnetic steel, and use the finite element analysis software to count the remanence Br value of the magnetic steel;

A2. The magnetic steel is fixed in the demagnetization equipment, and the direction of the demagnetization magnetic field is required to be opposite to the magnetization direction of the magnetic steel;

A3. Apply the first demagnetization magnetic field, and the first demagnetization magnetic field strength (Hi, i=1, 2...) should be less than half of the lowest Hcj value of the magnetic steel material;

A4. Take the magnetic steel out of the demagnetization equipment;

A5. Test the M2 magnetic moment value of the taken out magnetic steel,

A6. Calculate and judge whether the secondary magnetic moment value satisfies (M1-M2)/M1≤5%;

A7. If (M1-M2)/M1≤5% is satisfied, you need to return to the above step A2, fix the magnetic steel in the demagnetization equipment for demagnetization treatment, the demagnetization magnetic field value has increased compared with the previous time, and the increase value should be less than The minimum intrinsic coercive force value Hcj of the type of magnetic steel material to be detected is 0.02 to 0.1, and the above steps A2 to A6 are continuously performed in this cycle;

A8. Until the magnetic moment value satisfies (M1-M2)/M1≥5%, record the demagnetizing field value Hi at this time;

A9. The knee coercivity value Hk required for the final magnetic steel performance test is between Hi-1 and Hi;

A10. After performing the above steps A1 to A9, continue to fix the magnetic steel in the demagnetization equipment;

A11. Continue to apply the second demagnetizing field Hj, and the increase value of applying the second demagnetizing field (Hj, j=i+1, i+2...) should be less than 0.01-0.05 of the minimum intrinsic coercivity value Hcj of the magnetic steel material ;

A12. Take out the magnetic steel, and then measure the M3 magnetic moment value of the magnetic steel;

A13. Calculate and judge whether the secondary magnetic moment value satisfies (M1-M3)/M1≤100%;

A14. In the above step A12, if M3≥0, then it is necessary to continue demagnetization of the magnetic steel in the demagnetization equipment, return to the above-mentioned step A10, continue to fix the magnetic steel in the demagnetization equipment, and continue to demagnetize the magnetic steel. , and the demagnetization magnetic field value has increased compared to the previous time, and the increased value is less than 0.01-0.05 of the minimum intrinsic coercive force value Hcj value of the magnetic steel material; in this cycle, continue to perform the above steps A10-A14;

A15. Until M3<0, record the demagnetizing field value Hj at this time;

A16. In the above step A13, if the measured value cannot satisfy (M1-M3)/M1≤100%, record the corresponding demagnetizing field Hj at this time; if the measured value can satisfy (M1-M3) /M1≤100%, return to the above-mentioned step A10, and continue to perform the above-mentioned steps A10-A14;

A17. The minimum intrinsic coercivity value Hcj required for the final magnetic steel performance test is between Hj-1 and Hj;

In the above steps: M1 is the initial magnetic moment value of the test magnetic steel in the normal temperature environment; M2 is the magnetic moment value obtained through steps 3 and 4. As long as the magnetic moment value is obtained by testing in two steps, it can be called M2;

Similar to M2, the magnetic moment value obtained after step 6 or step 7 can be called M3 as long as the magnetic moment value obtained in the two steps is tested; Hi represents the first demagnetization field strength increased cyclically, and i represents the corresponding demagnetization The number of times, for example, i=5 is the demagnetization field strength after the 5th increase, and the corresponding i-1 is the demagnetization field strength after the 4th increase; Hj represents the second demagnetization field strength of the cyclic increase, j represents the corresponding demagnetization times, For example, j=10 is the demagnetization field strength after the 10th increase, and the corresponding j-1 is the demagnetization field strength after the ninth increase. Under the premise of not destroying the magnetic steel, the finished magnetic steel of the same industry can be directly detected and analyzed. The detection and testing speed is fast, the detection efficiency is high, and the detection accuracy is high.

Preferably, the demagnetization device includes a yoke and a pole piece, and a copper coil is arranged inside the pole piece, and a demagnetization magnetic field is generated in the working air gap after being energized. Improve the simplicity and effectiveness of demagnetization equipment.

Preferably, the strength of the magnetic field is adjusted by controlling the current/voltage of the copper coil. Improve the flexibility and effectiveness of demagnetization operation control.

The beneficial effects of the present invention are: 1. Under the premise of not destroying the magnetic steel, the finished magnetic steel can maintain the initial shape and surface coating without damage, directly test to obtain performance data, and avoid becoming a standard sample block after secondary processing Retest performance; 2. It can directly test and analyze the finished magnetic steel products of the same industry, with fast detection and testing speed, high detection efficiency and high detection accuracy; 3. The present invention can directly test the finished product, and is especially suitable for testing the Cylindrical magnetic steel; 4. Compared with the current hysteresis loop tester, the present invention does not need to customize the corresponding test coil, and there is no strict requirement for thickness; 5. Compared with the current surface magnetism estimation and demagnetization ratio analysis , the accuracy of the present invention is higher; 6. The test cycle of the present invention is short, and the test cost is low.

Description of drawings:

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

Fig. 1 is the test flow structure schematic diagram of the performance test method of finished magnetic steel of the present invention.

2 is a schematic diagram of the main structure of the demagnetization equipment in the performance testing method of the finished magnetic steel of the present invention.

3 is a schematic diagram of the M-H curve formed between the strength of the demagnetizing magnetic field and the value of the coercive force at the knee point in the method for testing the performance of the finished magnetic steel of the present invention.

4 is a schematic diagram of the M-H curve formed between the strength of the demagnetizing magnetic field and the value of the intrinsic coercive force in the method for testing the performance of the finished magnetic steel of the present invention.

Detailed ways

In the embodiment 1 shown in FIG. 1, a method for testing the performance of a finished magnetic steel includes the following testing steps

A1. Test the M1 magnetic moment value 02 of the magnetic steel, and use the finite element analysis software to count the remanence Br value of the magnetic steel;

A2. Fix the magnetic steel in the demagnetization equipment 03, and the direction of the demagnetization magnetic field is required to be opposite to the magnetization direction of the magnetic steel;

A3. Apply the first demagnetization magnetic field 04, and the first demagnetization magnetic field intensity (Hi, i=1, 2...) should be less than half of the lowest Hcj value of the magnetic steel material;

A4. Take the magnetic steel out of the demagnetization equipment 05;

A5. Take the magnetic steel taken out in step A4, and test the M2 magnetic moment value of the magnetic steel taken out.

A6. Calculate and judge whether the secondary magnetic moment value satisfies (M1-M2)/M1≤5% of 06;

A7. If (M1-M2)/M1≤5% is satisfied, you need to return to the above step A2, fix the magnetic steel in the demagnetization equipment for demagnetization treatment, the demagnetization magnetic field value has increased compared with the previous time, and the increase value should be less than The minimum intrinsic coercive force value Hcj of the type of magnetic steel material to be detected is 0.02 to 0.1, and the above steps A2 to A6 are continuously performed in this cycle;

A8. Until the magnetic moment value satisfies (M1-M2)/M1≥5%, record the demagnetizing field value Hi 07 at this time;

A9. The knee coercivity value Hk required for the final magnetic steel performance test is between Hi-1 and Hi;

A10. After performing the above steps A1 to A9, continue to fix the magnetic steel in the demagnetization equipment 08;

A11. Continue to apply the second demagnetization field 09, and the increase value of the second demagnetization field (Hj, j=i+1, i+2...) should be less than 0.01-0.05 of the minimum intrinsic coercivity value Hcj of the magnetic steel material ;

A12. Take out the magnetic steel, and then measure the M3 magnetic moment value of the magnetic steel 10;

A13. Calculate and judge whether the secondary magnetic moment value satisfies (M1-M3)/M1≤100%11;

A14. In the above step A12, if M3≥0, then it is necessary to continue demagnetization of the magnetic steel in the demagnetization equipment, return to the above-mentioned step A10, continue to fix the magnetic steel in the demagnetization equipment, and continue to demagnetize the magnetic steel. , and the demagnetization magnetic field value has increased compared to the previous time, and the increased value is less than 0.01-0.05 of the minimum intrinsic coercive force value Hcj value of the magnetic steel material; in this cycle, continue to perform the above steps A10-A14;

A15. Until M3<0, record the corresponding demagnetizing field value Hj 12 at this time;

A16. In the above step A13, if the measured value cannot satisfy (M1-M3)/M1≤100%, record the corresponding demagnetizing field Hj 12 at this time; if the measured value can satisfy (M1-M3 )/M1≤100%, return to the above-mentioned step A10, and continue to perform the above-mentioned steps A10-A14;

A17. The minimum intrinsic coercivity value Hcj required for the final magnetic steel performance test is between Hj-1 and Hj;

In the above steps: M1 is the initial magnetic moment value of the test magnetic steel in the normal temperature environment; M2 is the magnetic moment value obtained through steps 3 and 4. As long as the magnetic moment value is obtained by testing in two steps, it can be called M2;

Similar to M2, the magnetic moment value obtained after step 6 or step 7 can be called M3 as long as the magnetic moment value obtained in the two steps is tested; Hi represents the first demagnetization field strength increased cyclically, and i represents the corresponding demagnetization The number of times, for example, i=5 is the demagnetization field strength after the 5th increase, and the corresponding i-1 is the demagnetization field strength after the 4th increase; Hj represents the second demagnetization field strength of the cyclic increase, j represents the corresponding demagnetization times, For example, j=10 is the demagnetization field strength after the 10th increase, and the corresponding j-1 is the demagnetization field strength after the ninth increase. The above-mentioned magnetic moment value M1 is obtained through the "Helmholtz coil + electronic fluxmeter" test, which is an existing conventional test method. The test steps are as follows: 1. Put the product to be tested in the center of the coil, and the magnetization direction is parallel to the axial direction of the coil; 2. Return the electronic flux meter to zero; 3. Take the product to be tested out of the coil, and read the current The indication is M1; the magnetic moment value M3 is obtained through the "Helmholtz coil + electronic fluxmeter" test. The test steps are as follows: 1. Place the product to be tested in the center of the coil, and the magnetization direction is parallel to the coil axial direction; 2. The electronic flux meter is reset to zero; 3. The product to be tested is taken out of the coil, and the reading at this time is M3. The demagnetization equipment includes a yoke and a pole piece. There is a copper coil inside the pole piece, and a demagnetization magnetic field is generated in the working air gap after being energized. The strength of the magnetic field is adjusted by controlling the current/voltage of the copper coil. The finite element analysis software used is the analysis software in the prior art.

Test principle:

1. The demagnetization equipment is mainly composed of a yoke 20 and a pole shoe 30 (see Figure 2). There is a copper coil inside the pole shoe 30. After electrification, a demagnetization magnetic field can be generated in the working air gap 31; the strength of the magnetic field can be controlled by the copper coil. The magnitude of the current/voltage can be adjusted; the demagnetization equipment can use the existing hysteresis loop tester to achieve the effect of demagnetization.

2. On the M-H curve (see Figure 3), when the demagnetization magnetic field strength H is less than the knee point coercivity value Hk, the reduction ratio of the magnetic moment will not exceed 10%, such as the position of Hi-1; when the demagnetization field strength H When greater than Hk, the reduction ratio of the magnetic moment will rapidly exceed 10%. For example the location of Hi. The size of the range of Hk can be determined by finding the range of demagnetizing field strength where the value of the magnetic moment varies by more than 10%.

3. On the M-H curve (see Figure 4), when the demagnetization magnetic field strength H is less than the intrinsic coercivity value Hcj, the value of the magnetic moment is positive, such as the position of Hj-1; when the demagnetization magnetic field strength H is greater than Hcj, The value of the magnetic moment is negative, such as the position of Hj; the range of Hcj can be determined by finding the corresponding demagnetizing field strength range from positive to negative.

In the description of the positional relationship of the present invention, the appearance of terms such as "inner", "outer", "upper", "lower", "left", "right", etc. to indicate orientation or positional relationship is based on the orientation or position shown in the drawings. The positional relationship is only for the convenience of describing the embodiments and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

The above content and structure describe the basic principles, main features and advantages of the present invention, which should be understood by those skilled in the art. What is described in the above examples and specification is only to illustrate the principle of the present invention, without departing from the spirit and scope of the present invention, the present invention will also have various changes and improvements, and these changes and improvements all belong to the scope of the claimed invention. Inside. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (3)

1. A method for testing the performance of finished magnetic steel is characterized by comprising the following testing steps:

A1. testing the magnetic moment value M1 of the magnetic steel, and counting the residual magnetism Br value of the magnetic steel by using finite element analysis software;

A2. fixing the magnetic steel in a demagnetization device, wherein the direction of a demagnetization magnetic field is required to be opposite to the magnetization direction of the magnetic steel;

A3. applying a first demagnetizing field, wherein the intensity of the first demagnetizing field (Hi, i is 1,2 …) is less than half of the lowest Hcj value of the magnetic steel material;

A4. taking out the magnetic steel from the demagnetization equipment;

A5. the taken-out magnetic steel is tested for the magnetic moment value of M2,

A6. calculating and judging whether the quadratic magnetic moment value meets (M1-M2)/M1 and is less than or equal to 5 percent;

A7. if the magnetic steel meets the condition that (M1-M2)/M1 is less than or equal to 5 percent, returning to the step A2, fixing the magnetic steel in demagnetization equipment for demagnetization, wherein the value of a demagnetization magnetic field is increased relative to the previous time, the increased value is less than 0.02-0.1 of the lowest intrinsic coercivity value Hcj of the detected type magnetic steel material, and circularly and continuously executing the steps A2-A6;

A8. recording the demagnetization field value Hi until the magnetic moment value meets (M1-M2)/M1 is more than or equal to 5 percent;

A9. finally, the coercivity value Hk of the knee point required by the performance detection of the magnetic steel is between Hi-1 and Hi;

A10. after the steps A1-A9 are executed, the magnetic steel is continuously fixed in demagnetization equipment;

A11. continuously applying a second demagnetizing field Hj (the j is i +1, i +2 …), wherein the increment value of the second demagnetizing field Hj is less than 0.01-0.05 of the lowest intrinsic coercive force value Hcj of the magnetic steel material;

A12. taking out the magnetic steel, and then measuring the M3 magnetic moment value of the magnetic steel;

A13. calculating and judging whether the quadratic magnetic moment value meets (M1-M3)/M1 and is less than or equal to 100 percent;

A14. in the step a12, if M3 is not less than 0, the magnetic steel needs to be continuously placed in demagnetization equipment for demagnetization, the step a10 is executed, the magnetic steel is continuously fixed in the demagnetization equipment, the magnetic steel is continuously demagnetized, the value of the demagnetized magnetic field is increased relative to the previous value, and the increased value is less than 0.01 to 0.05 of the lowest intrinsic coercive force Hcj value of the magnetic steel material; the steps A10 to A14 are continuously executed in the circulation;

A15. recording the demagnetization field value Hj until M3 is less than 0;

A16. in the step A13, if the measured value can not satisfy (M1-M3)/M1 is less than or equal to 100%, recording the corresponding demagnetizing field Hj at the moment; if the measured value can satisfy (M1-M3)/M1 is less than or equal to 100 percent, returning to the step A10, and continuing to execute the steps A10 to A14;

A17. finally, the lowest intrinsic coercivity value Hcj required by the performance detection of the magnetic steel is between Hj-1 and Hj;

the steps are as follows: m1 is the initial magnetic moment value of the test magnetic steel under the normal temperature environment; m2 is the magnetic moment value obtained after step 3 and step 4, and can be called M2 as long as the magnetic moment value is obtained by testing in two steps; similar to M2, the magnetic moment values obtained through step 6 or step 7, so long as the magnetic moment values are tested in two steps, can be referred to as M3; hi represents the first demagnetizing field strength of cyclic increase, i represents the corresponding demagnetizing times, for example, i-5 is the demagnetizing field strength after 5 th increase, and corresponding i-1 is the demagnetizing field strength after 4 th increase; hj represents the second demagnetizing field strength of cyclic increase, j represents the corresponding demagnetizing times, for example, j equals 10 is the demagnetizing field strength after 10 th increase, and j-1 is the demagnetizing field strength after 9 th increase.

2. A method for testing the performance of finished magnetic steel as claimed in claim 1, wherein said demagnetizing equipment includes yoke and pole shoe, the pole shoe has copper coil inside, after power on, it generates demagnetizing field in the working air gap.

3. A method for testing the performance of a finished magnetic steel according to claim 2, wherein the strength of the magnetic field is adjusted by controlling the current/voltage of the copper coil.

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