Method for adjusting the uniformity of the magnetic field strength of the magnetic poles of a radiation-oriented magnetic ring

Abstract

The application relates to a radiation orientation magnetic ring magnetic pole magnetic field strength uniformity adjusting method, and belongs to the technical field of magnetic field uniformity control. The method solves the problems that in the prior art, the difference between the magnetic poles of a magnetic ring is large, the magnetic field strength uniformity of the magnetic poles of the magnetic ring is not high, and the consistency of the magnetic field strength distribution of the magnetic poles of the magnetic ring is difficult to accurately control and adjust. The radiation orientation magnetic ring magnetic pole magnetic field strength uniformity adjusting method sequentially adjusts the local magnetic field strength of the magnetic poles of the magnetic ring in sequence under an open circuit environment. The adjusting method is that an adjusting magnetic field is applied to the magnetic pole at a local position of a single magnetic pole, and the surface area of the magnetic pole is heated to a certain temperature. The method realizes the adjustment and control of a high-uniformity radiation orientation magnetic ring.

Description

Technical Field

[0001] This invention relates to the field of magnetic field uniformity control technology, and in particular to a method for adjusting the uniformity of magnetic field strength of a radial orientation magnetic ring. Background Technology

[0002] Magnetic materials, as an important class of functional materials, have been widely used in advanced manufacturing fields such as precision machine tools, aerospace equipment, industrial robots, and power equipment. Radial-oriented magnetic rings are a type of magnetic material with a special orientation structure. Their grains are arranged radially in the direction of easy magnetization, resulting in a compact overall structure, high assembly tightness, small stray magnetic field, and high output magnetic field stability. They are particularly suitable for high-end permanent magnet motors and high-precision magnetic sensors.

[0003] Traditional methods for manufacturing radiation-oriented magnetic rings include splicing, sintering, bonding, and hot-pressing / hot-deformation integral magnetic rings. Magnetic rings prepared by different methods have different properties. According to the requirements of the service environment, magnetic rings with corresponding magnetic field distribution and strength can be made by internal and external unipolar radiation magnetization and multipolar radiation magnetization.

[0004] To ensure the stable and reliable operation of magnetic equipment, the magnetic field strength distribution output by the magnetic ring poles usually needs to be highly consistent. Due to limitations in manufacturing processes and other aspects, it is difficult for the structure and magnetization state of the magnetic ring to be completely consistent, resulting in differences in the magnetic field strength distribution of the magnetic ring poles. The difference in non-uniformity between the magnetic poles of existing magnetic rings generally exceeds 4%, making it very difficult to further improve the consistency of the magnetic field strength distribution by improving the uniformity of the magnetic ring itself.

[0005] To meet the application requirements of higher uniformity magnetic rings, optimization can be achieved by adding shimming plates, or by partially demagnetizing the magnetized area of ​​the magnetic ring with an external magnetic field. These methods require complex designs, have limited operating space, and are difficult to adjust the magnitude of magnetic field changes more accurately. They are also not suitable for small-sized multi-pole magnetic rings with many magnetic poles. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a method for adjusting the uniformity of magnetic field strength of a radially oriented magnetic ring, in order to solve at least one of the following problems: large difference in inhomogeneity between magnetic poles of existing magnetic rings, low uniformity of magnetic field strength of magnetic ring poles, and difficulty in accurately controlling and adjusting the consistency of magnetic field strength distribution of magnetic ring poles.

[0007] A method for adjusting the uniformity of magnetic field strength of a radially oriented magnetic ring poles involves sequentially adjusting the magnetic field strength of the magnetic ring poles in an open-circuit environment. The adjustment method involves applying an adjustment magnetic field to the local position of a single magnetic pole while simultaneously heating the surface area of ​​that magnetic pole to a certain temperature.

[0008] Furthermore, the adjustment order is to adjust the magnetic field strength of each magnetic pole in descending order of the difference between the magnetic field strength of the magnetic pole and the target value.

[0009] Preferably, the local location of the single magnetic pole is the peak region of each magnetic pole, and the polar angle width is no greater than 20°.

[0010] It should be noted that the magnitude of the adjusting magnetic field applied during the adjustment process is no greater than 5000 Gs, and the distance from the magnetic ring surface is no greater than 0.5 mm.

[0011] Furthermore, the temperature range applied during the adjustment process is 150–400°C, and the temperature-affected area is no larger than 1 mm. 2 Each time the duration is no more than 3 seconds.

[0012] It is worth noting that the local adjustment number of the magnetic field strength of each magnetic pole is >1, and the magnitude of the magnetic pole difference in a single adjustment ranges from 1 to 70 Gs.

[0013] Specifically, before the uniformity adjustment of the magnetic field strength of the magnetic ring poles, the magnetic ring is subjected to unipolar radiation orientation magnetization or multipolar radiation orientation magnetization. The magnetic ring is placed in the corresponding orientation magnetic field for saturation magnetization. After magnetization, the magnetic field strength of the magnetic ring poles is 1000 to 5000 Gs, and the deviation range of the strength of each magnetic pole is 2 to 15%.

[0014] Preferably, the magnetic ring size characteristics applicable to the local adjustment method of magnetic ring magnetic pole magnetic field strength include: magnetic ring axial height not less than 1mm, magnetic ring radius range of 5 to 30mm, and inner-outer diameter ratio of 0.55 to 0.95.

[0015] For example, the method for local adjustment of magnetic field strength of magnetic ring poles is applicable when the magnetic ring is made of permanent magnet material, with a coercivity of not less than 10 kOe and a magnetic energy product of not less than 10 MGOe.

[0016] Specifically, the uniformity of the magnetic field strength distribution of the magnetic ring poles is less than 2% after adjustment.

[0017] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0018] 1. This invention addresses the problem that the magnetic field adjustment position of a multi-pole magnetic ring needs to be consistent with that during orientation preparation. It adopts a local magnetization characteristic adjustment method, processes the magnetic poles of the radiating orientation magnetic ring sequentially according to the magnitude of the magnetic pole strength deviation, and strictly controls the pole angle width of the adjustment position to reduce the impact on adjacent magnetic poles and improve the adjustment accuracy.

[0019] 2. This invention addresses the problem that the magnetization state of small-sized magnetic rings is easily affected by external magnetic fields and exhibits significant hysteresis. It employs a combination of magnetic and temperature fields to adjust the local magnetization state of the magnetic poles, and precisely controls the application area of ​​the magnetic and temperature fields, as well as the time and number of adjustments per adjustment. Through focused processing of a small area in a short time, it achieves a significant improvement in adjustment stability and accuracy, effectively reduces adjustment deviation, and minimizes magnetic performance loss outside the processing area.

[0020] 3. This invention employs a local magnetization characteristic adjustment method. The magnetic poles of the radiation-oriented magnetic ring are processed sequentially according to the magnitude of the magnetic pole strength deviation. The pole angle width of the adjustment position is strictly controlled. The local magnetization state of the magnetic poles is adjusted by combining magnetic field and temperature field, which significantly improves the stability and accuracy of adjustment, effectively reduces adjustment deviation, and reduces magnetic performance loss outside the processing area. As a result, a magnetic field strength distribution with high uniformity is obtained, and the magnetic field strength deviation of the magnetic ring poles reaches within 2%, meeting the application requirements of high uniformity magnetic rings.

[0021] 4. This invention utilizes a method of combining magnetic field and temperature field processing to adjust the local magnetization characteristics of magnetic ring poles, thereby achieving accuracy and stability in the adjustment and control of magnetic field strength difference between magnetic poles. It can obtain a radially oriented magnetic ring with excellent uniformity of magnetic field strength between magnetic poles, while significantly improving the axial consistency of the magnetic ring. It has virtually no impact on the magnetic properties of adjacent regions of the localized adjustment of the magnetic ring.

[0022] 5. This invention precisely controls the application area of ​​the magnetic field and temperature field, as well as the time and number of adjustments per adjustment. By focusing on a small area for a short time, it effectively reduces the impact on adjacent areas and achieves higher stability and control accuracy.

[0023] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0024] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0025] Figure 1 Magnetic field strength distribution curve after magnetic ring pole adjustment in Embodiment 2 of the present invention;

[0026] Figure 2 The magnetic field strength distribution curve of the axial magnetic pole of the magnetic ring in Embodiment 3 of the present invention. Detailed Implementation

[0027] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0028] For large magnets, the uniformity of the magnetic field can be adjusted by adding shimming plates. Shimming plates are generally metal plates used to adjust the uniformity of the magnetic field. When adjusting the magnetic field, these shimming plates are placed inside or outside the magnet. The uniformity of the magnetic field is optimized by changing their position or number. A large placement space is required.

[0029] Existing small-sized multipole magnetic rings are usually manufactured with the magnetic field strength deviation of the magnetic poles kept within a low range (generally above 4%). However, as the requirements for the use of small-sized multipole magnetic rings in high-precision fields such as motors become increasingly stringent, a magnetic field strength deviation of more than 4% is no longer sufficient to meet the application requirements of high-precision fields, and it is necessary to further reduce the magnetic field strength deviation.

[0030] Small magnetic rings are limited by size, and multi-pole magnetic rings are limited by geometry, resulting in limited operating space and difficulty in placing shimming plates. It is also difficult to determine the appropriate magnetic field strength and precisely control the adjustment amount by only partially demagnetizing the magnetized area of ​​the magnetic ring with an external magnetic field.

[0031] The magnetic field adjustment position of multi-pole magnetic rings needs to be consistent with that during orientation preparation. Any misalignment may affect the magnetic field distribution and performance of the final product, which places higher demands on the precise control of the adjustment process. Small-sized magnetic rings, on the other hand, exhibit a more significant interaction between their magnetization state and the external magnetic field. Their magnetic field strength is more easily affected by external magnetic fields, causing fluctuations. Furthermore, due to their size limitations, hysteresis is more pronounced, resulting in poor magnetic field stability, requiring even more precise control to adjust their magnetic field strength. In summary, small-sized and multi-pole magnetic rings, due to their size limitations, design complexity, and the need for precise magnetic field adjustment, place higher demands on the uniformity of magnetic field strength adjustment.

[0032] A specific embodiment of the present invention discloses a method for adjusting the uniformity of magnetic field strength of a radial orientation magnetic ring pole. In an open-circuit environment, the magnetic field strength of the magnetic ring poles is adjusted locally in sequence. The adjustment method is to apply an adjustment magnetic field to the pole at a local position of a single pole, while heating the surface area of ​​the pole to a certain temperature.

[0033] Specifically, the adjustment order is to adjust the magnetic field strength of each magnetic pole in descending order of the difference between the magnetic field strength of the magnetic pole and the target value, which can gradually reduce the fluctuation of the magnetic field and thus improve the stability of the magnetic field.

[0034] Preferably, the local location of the single magnetic pole is the peak region of each magnetic pole, and the included pole angle width is no more than 20°. If the pole angle width is too large, it will affect the magnetic properties of the adjacent regions.

[0035] Furthermore, the magnitude of the adjusting magnetic field applied during the adjustment process is no greater than 5000 Gs, and the distance from the magnetic ring surface is no greater than 0.5 mm. Preferably, the adjusting magnetic field is 2000 Gs, 2500 Gs, 3000 Gs, 3500 Gs, 4000 Gs, 4500 Gs, or 5000 Gs.

[0036] If the applied magnetic field strength is too high, it will cause a significant change in the magnetization state of the magnetic ring or a large loss in the magnetic field strength, thereby causing the magnetic ring to fail to meet the requirements for use in magnetic applications.

[0037] It should be noted that the regulating magnetic field is applied through a demagnetizing coil.

[0038] Furthermore, the localized magnetization characteristics of the magnetic ring poles adjust the surface heating temperature range from 150 to 400°C, and the temperature effect area is no larger than 1 mm. 2 The duration of each heating cycle shall not exceed 3 seconds. Preferably, the heating temperature is 150℃, 200℃, 250℃, 300℃, 350℃, or 400℃.

[0039] The heating method for the magnetic pole surface area is through heat conduction by the heater, and the range of the area of ​​action is controlled by the contact area between the heater and the magnetic pole surface.

[0040] It is worth noting that the local adjustment number of the magnetic field strength of each magnetic pole is >1, and the magnitude of the magnetic pole difference in a single adjustment ranges from 1 to 70 Gs.

[0041] During the local adjustment of the magnetic field strength of the magnetic ring poles, the magnetization state of the magnetic poles changes under the combined action of the magnetic field of the demagnetizing coil and the high temperature of the surface layer, forming a continuous micro-demagnetizing region. The range of the demagnetizing region can be effectively controlled, thereby achieving control over the magnitude of the magnetic field strength of the magnetic poles and reducing the magnetic pole deviation.

[0042] It should be noted that before the magnetic field strength of the magnetic ring poles is adjusted for uniformity, the magnetic ring is subjected to unipolar radiation orientation magnetization or multipolar radiation orientation magnetization. The magnetic ring is placed in the corresponding orientation magnetic field for saturation magnetization. After magnetization, the magnetic field strength of the magnetic ring poles is 1000 to 5000 Gs, and the deviation range of each magnetic pole strength is 2 to 15%.

[0043] After the magnetic ring is radiatively oriented and magnetized, the distribution of the magnetic field strength of the magnetic poles of the magnetic ring is obtained in an open-circuit state. Based on the distribution, a target value for uniformity adjustment is selected. The magnitude of the magnetic field strength after the magnetic poles of the magnetic ring are saturated and magnetized is detected. Based on the magnitude of the magnetic pole strength deviation, the target value for uniformity adjustment of the magnetic ring is determined to achieve the uniformity requirements of the magnetic ring.

[0044] It should be noted that the magnetic ring magnetic field strength local adjustment method is applicable to magnetic ring size characteristics including: magnetic ring axial height not less than 1mm, magnetic ring radius range of 5 to 30mm, and inner-outer diameter ratio of 0.55 to 0.95;

[0045] The method for local adjustment of magnetic field strength of magnetic ring poles is applicable when the magnetic ring is made of permanent magnet material, with a coercivity of not less than 10 kOe and a magnetic energy product of not less than 10 MGOe.

[0046] Preferably, the uniformity of the magnetic field strength distribution of the magnetic ring poles is less than 2% after adjustment.

[0047] In summary, this invention employs a localized magnetization characteristic adjustment method to sequentially process the magnitude of the magnetic pole deviation of the radiation orientation magnetic ring. Based on the control range of the magnetic pole position region, different magnetic fields and temperatures are used to compositely adjust the localized magnetization state of the magnetic poles. This significantly improves the stability and accuracy of the adjustment, effectively reduces adjustment deviation, and minimizes magnetic performance loss outside the processing area. Consequently, a highly uniform magnetic field strength distribution is obtained, with the uniformity of the magnetic field strength distribution of the magnetic ring poles reaching within 2%, meeting the application requirements of highly uniform magnetic rings.

[0048] The method for adjusting the uniformity of magnetic field strength of the magnetic poles of the radial orientation magnetic ring of the present invention will be described below with reference to specific embodiments.

[0049] Example 1

[0050] This embodiment provides a method for adjusting the uniformity of the magnetic field strength of a radial orientation magnetic ring.

[0051] The object being processed is a multi-pole magnetic ring with the following dimensions: ring radius 16mm, inner-to-outer diameter ratio 0.78, ring height 2mm, and 4 poles. After the magnetic poles are saturated with magnetization, the magnetic field strength is: N pole: 3651Gs, 3884Gs, S pole: 3738Gs, 3977Gs; the magnetic pole strength deviation is 4.3%.

[0052] The specific process is as follows:

[0053] Step 1: Adjust the target value and determine: Set the target value for magnetic ring uniformity adjustment to 3700Gs;

[0054] Step 2, Local adjustment of magnetic field of magnetic poles: Under open circuit environment, adjust each magnetic pole in order of decreasing difference between the magnetic pole strength and the target value, and adjust in the following order: N pole 3884Gs, S pole 3977Gs, N pole 3651Gs, S pole 3738Gs area, with a maximum width of 10° of the pole angle of the adjustment area.

[0055] The magnetizing coil is positioned 0.5 mm away from the peak region of each magnetic pole, and a magnetic field of 4500 Gs is applied. Simultaneously, the surface region of the magnetic ring poles is heated to 350°C, acting on a 0.3 mm... 2 The processing time is 2 seconds per cycle, and it is adjusted in 5 cycles with a maximum adjustment difference of 50 Gs.

[0056] Under the combined action of the magnetic field of the demagnetizing coil and the surface temperature, the magnetization state of the region with high magnetization intensity of the magnetic pole changes, forming a continuous micro-demagnetizing zone, thereby adjusting and reducing the deviation of the magnetic field strength of the magnetic pole. After adjustment, the magnetic ring naturally returns to the initial temperature, and the demagnetizing coil is turned off.

[0057] After testing and adjustment, the corresponding magnetic pole sizes are: N pole: 3647Gs, 3749Gs, S pole: 3732Gs, 3723Gs. The magnetic pole strength deviation after adjustment is 1.77%, which significantly improves the adjustment control accuracy and obtains excellent uniformity in the magnetic pole distribution of the magnetic ring.

[0058] Example 2

[0059] This embodiment provides a method for adjusting the uniformity of the magnetic field strength of a radial orientation magnetic ring.

[0060] The object of the treatment was a sintered radiation-oriented permanent magnet ring with a radius of 22 mm, an inner-to-outer diameter ratio of 0.9, and a height of 12 mm. The magnetic properties of the directly circumferentially cut sample of the radiation-oriented magnet ring were a coercivity of 23 kOe and a magnetic energy product of 19 MGOe. The outer circumference of the magnet ring was the N pole and the inner side was the S pole. The deviation of the magnetic field distribution of the N pole on the outer circumference of the magnet ring was adjusted. After saturation magnetization, the magnetic field strength distribution of the N pole was as follows: maximum 2729 Gs, minimum 2187 Gs, and magnetic pole strength deviation 11.03%.

[0061] The specific process is as follows:

[0062] Step 1: Adjust the target value and determine: The target value for adjusting the uniformity of the magnetic ring is 2200 Gs;

[0063] Step 2: Local Adjustment of Magnetic Pole Magnetic Field: Test the areas where the N pole deviates from the target value along the circumference and mark them in order of magnitude of the difference. Place the adjusting coil directly opposite the area where the magnetic pole intensity deviates, with a corresponding pole angle width of 15° and a distance of 0.1 mm for each area. Apply a magnetic field of 5000 Gs, while simultaneously heating the surface area of ​​the magnetic ring pole to 400°C. The area of ​​the applied magnetic field is 1 mm². 2 The processing time is 3 seconds, and the adjustment is carried out in 15 times. The maximum adjustment difference is 70Gs. The magnetic field strength of the magnetic pole is reduced along the N pole axis from large to small according to the difference between the magnetic field strength and 2200Gs. As the area of ​​magnetization change increases continuously, the magnetic field strength distribution of the magnetic ring tends to be uniform. After adjustment, the magnetic ring naturally returns to the initial room temperature.

[0064] After testing and adjustment, the magnetic field strength distribution of the outer circumference N pole of the magnetic ring was as follows: maximum value 2263 Gs, minimum value 2176 Gs. The deviation of the circumferential magnetic pole strength distribution after adjustment was 1.96%, achieving a significant improvement in the uniformity of the magnetic field strength of the magnetic ring. The adjusted magnetic field strength distribution curve is shown below. Figure 1 As shown.

[0065] Example 3

[0066] This embodiment provides a method for adjusting the uniformity of the magnetic field strength of a radial orientation magnetic ring.

[0067] The object of the treatment was a multi-pole magnetized radially oriented magnetic ring with a radius of 13.5 mm, an inner-to-outer diameter ratio of 0.59, a height of 10 mm, and magnetic properties of coercivity of 15 kOe and energy product of 31 MGOe. The magnetic ring was magnetized with a multi-pole orientation and had 10 poles. The magnetic field strength of the corresponding axial poles was measured sequentially at 2 mm intervals along the axial height direction. After multi-pole saturation magnetization, the magnetic field strengths of the five corresponding S poles at equal intervals along the axial direction were 2878 Gs, 3021 Gs, 2804 Gs, 2738 Gs, and 2763 Gs, respectively. The axial magnetic pole strength of the multi-pole magnetic ring deviated by 6.3%.

[0068] The specific process is as follows:

[0069] Step 1: Adjust the target value and determine: The target value for adjusting the uniformity of the magnetic ring is 2800 Gs;

[0070] Step 2, Local Adjustment of Magnetic Pole Magnetic Field: In an open-circuit environment, adjust the difference between the magnetic pole strength and the target value. The adjustment sequence is: 3021Gs, 2878Gs, 2738Gs, 2763Gs, 2804Gs regions. The maximum width of the pole angle in the adjustment region is 5°. Position the magnetic adjustment coil directly towards the peak region of a single magnetic pole position at a distance of 0.2mm, apply a magnetic field of 2000Gs, and simultaneously heat the surface area of ​​the magnetic ring pole to 150℃, applying a magnetic field of 0.6mm. 2 The processing time is 1 second. The magnetic pole strength is adjusted sequentially along the axial direction according to its magnitude. The adjustment is carried out in 6 steps, with a maximum adjustment difference of 25 Gs.

[0071] Under the combined action of the magnetic field and the high surface temperature, the magnetization state of the axial magnetic pole position changes, reducing the magnetization intensity of the magnetic pole. This results in the magnetic field strength deviation of the magnetic pole being reduced as required by the design. After adjustment, the magnetic ring naturally returns to its initial temperature.

[0072] After adjusting the axial magnetic poles, the corresponding magnetic pole intensities of the magnetic ring are 2811 Gs, 2827 Gs, 2802 Gs, 2729 Gs, and 2732 Gs, respectively. The deviation of the axial magnetic pole intensity after adjustment is 1.83%, achieving optimization of the axial magnetic pole uniformity and resulting in a magnetic ring with high uniformity. The axial magnetic field intensity distribution curve is shown below. Figure 2As shown (adjusted δ(B) T )).

[0073] Comparative Example 1

[0074] This embodiment provides a method for adjusting the uniformity of the magnetic field strength of a radial orientation magnetic ring.

[0075] The size and magnetic properties of the magnetic ring are the same as in Example 1.

[0076] The specific process is basically the same as in Example 1, except that step 3 is different:

[0077] Step 3: Apply a magnetic field to the entire magnetic ring for adjustment: apply a magnetic field of 5000 Gs.

[0078] After testing and adjustment, the magnetic field strength distribution around the outer circumference of the magnetic ring is as follows: N pole: 3649 Gs, 3872 Gs; S pole: 3735 Gs, 3960 Gs. The deviation of the circumferential magnetic pole strength distribution after adjustment is 4.10%.

[0079] Comparative Example 2

[0080] This embodiment provides a method for adjusting the uniformity of the magnetic field strength of a radial orientation magnetic ring.

[0081] The size and magnetic properties of the magnetic ring are the same as in Example 2.

[0082] The specific process is basically the same as in Example 2, except that step 3 is different:

[0083] Step 3: Place the entire magnetic ring into an oven and heat it to 400℃ for 5 seconds. After adjustment, the magnetic ring will naturally return to its initial room temperature.

[0084] After testing and adjustment, the magnetic field strength distribution of the outer circumference N pole of the magnetic ring is as follows: maximum value 2611 Gs, minimum value 2039 Gs, and the deviation of the circumferential magnetic pole strength distribution after adjustment is 12.3%.

[0085] Comparative Example 3

[0086] This embodiment provides a method for adjusting the uniformity of the magnetic field strength of a radial orientation magnetic ring.

[0087] The size and magnetic properties of the magnetic ring are the same as in Example 3.

[0088] The specific process is basically the same as in Example 2, except that in step 3, the magnetic pole angle control area is larger, which is 30°.

[0089] After testing and adjustment, the corresponding magnetic pole strengths of the magnetic ring were 2835Gs, 2896Gs, 2787Gs, 2709Gs, and 2722Gs, respectively. The axial magnetic pole strength deviation of the multi-pole ring after adjustment was 3.81%.

[0090] Comparative Example 4

[0091] This embodiment provides a method for adjusting the uniformity of the magnetic field strength of a radial orientation magnetic ring.

[0092] The size and magnetic properties of the magnetic ring are the same as in Example 2.

[0093] The specific process is basically the same as in Example 2, except that in step 3, only one adjustment is performed, and the adjustment time is 1 minute.

[0094] The magnetic ring was tested and adjusted. The results showed that the magnetic field strength distribution of the N pole on the outer circumference of the magnetic ring after adjustment was: maximum value 2199 Gs, minimum value 1531 Gs, and the deviation of the magnetic pole strength distribution on the outer circumference after adjustment was 17.9%.

[0095] Comparative Example 5

[0096] This embodiment provides a method for adjusting the uniformity of the magnetic field strength of a radial orientation magnetic ring.

[0097] The size and magnetic properties of the magnetic ring are the same as in Example 2.

[0098] The specific process is basically the same as in Example 2, except that in step 3, the magnetic field is adjusted to be too strong, to 6000Gs.

[0099] The adjusted magnetic ring was tested, and the results showed that the magnetic field strength distribution around the outer circumference of the adjusted magnetic ring was: a maximum value of 2335 Gs and a minimum value of 2156 Gs. The deviation of the circumferential magnetic pole strength distribution after adjustment was 3.99%.

[0100] Comparative Example 6

[0101] This embodiment provides a method for adjusting the uniformity of the magnetic field strength of a radial orientation magnetic ring.

[0102] The size and magnetic properties of the magnetic ring are the same as in Example 2.

[0103] The specific process is basically the same as in Example 2, except that in step 3, the temperature is too high, at 500°C.

[0104] The adjusted magnetic ring was tested, and the results showed that the magnetic field strength distribution around the outer circumference of the adjusted magnetic ring was: a maximum value of 2327 Gs and a minimum value of 2011 Gs. The deviation of the circumferential magnetic pole strength distribution after adjustment was 7.28%.

[0105] As can be seen from Examples 1 to 3, the present invention utilizes the method of combining magnetic field and temperature field to process the local magnetization characteristics of magnetic ring poles, thereby achieving the accuracy and stability of magnetic field strength difference adjustment and control, and can obtain a radiation-oriented magnetic ring with excellent magnetic field strength uniformity. At the same time, it significantly improves the axial consistency of the magnetic ring, and the magnetic pole strength deviation meets the requirement of <2%.

[0106] As can be seen from Comparative Example 1 and Example 1, even after applying a magnetic field to the entire magnetic ring to adjust the magnetic field strength, the deviation in the distribution of the circumferential magnetic pole strength is still relatively large, at 4.10%.

[0107] As can be seen from Comparative Example 2 and Example 2, when the magnetic ring is heated as a whole and a temperature field is applied to adjust the magnetic field strength, the deviation of the circumferential magnetic pole strength distribution after adjustment is higher than that before adjustment, by 12.3%.

[0108] As can be seen from Comparative Example 3 and Example 3, the magnetic pole angle adjustment range is relatively large, and the deviation of the circumferential magnetic pole intensity distribution after adjustment is still relatively large, at 3.81%.

[0109] As can be seen from Comparative Example 4 and Example 2, each magnetic pole is only adjusted once for a relatively long time, resulting in poor stability and control accuracy. After adjustment, the deviation of the circumferential magnetic pole intensity distribution is higher than before adjustment, by 17.9%.

[0110] As can be seen from Comparative Example 5 and Example 2, the magnetic field strength applied during each adjustment is relatively large, resulting in excessive changes in the magnetization state of the magnetic ring. After adjustment, the deviation in the circumferential magnetic pole intensity distribution is still relatively large, at 3.99%.

[0111] As can be seen from Comparative Example 6 and Example 2, excessively high heating temperature leads to poor control accuracy. Even after adjustment, the deviation in the circumferential magnetic pole intensity distribution is still relatively large, at 7.28%.

[0112] In summary, the technology of this invention enables effective adjustment of magnetic rings with poor magnetic field uniformity, controls the magnitude of magnetic pole strength deviation in radiation-oriented magnetic rings, improves the uniformity of magnetic rings, and prepares highly uniform magnetic rings through composite control of local magnetization states, thus meeting the application requirements of high magnetic pole strength uniformity.

[0113] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for adjusting the uniformity of the magnetic field strength of a radially oriented magnetic ring, characterized in that, In an open-circuit environment, the magnetic field strength of the magnetic ring poles is adjusted locally in sequence. The adjustment method is to apply an adjustment magnetic field to the magnetic pole at a local position of a single magnetic pole, while heating the surface area of ​​the magnetic pole to a certain temperature. The radius of the magnetic ring is 5~30mm. The adjustment order is to adjust the magnetic field strength of each magnetic pole in descending order of the difference between the magnetic field strength of the magnetic pole and the target value. The local location of a single magnetic pole is the peak region of each magnetic pole, and the pole angle width is no greater than 20°. The magnitude of the adjusting magnetic field applied during the adjustment process shall not exceed 5000 Gs, and the distance from the magnetic ring surface shall not exceed 0.5 mm; The temperature range applied during the adjustment process is 150~400℃, and the temperature-affected area is no larger than 1mm. 2 Each time the duration is no more than 3 seconds; The number of times the magnetic field strength of each magnetic pole can be adjusted locally is greater than 1, and the range of the difference between magnetic poles in a single adjustment is 1~70Gs.

2. The adjustment method according to claim 1, characterized in that, Before the magnetic field strength of the magnetic ring poles is uniformly adjusted, the magnetic ring is subjected to unipolar or multipolar radiation orientation magnetization. The magnetic ring is then placed in the corresponding orientation magnetic field for saturation magnetization. After magnetization, the magnetic field strength of the magnetic ring poles is 1000~5000Gs, and the deviation range of each magnetic pole strength is 2~15%.

3. The adjustment method according to claim 1, characterized in that, The method for localizing the magnetic field strength of the magnetic ring poles is applicable to magnetic rings with the following size characteristics: axial height of the magnetic ring is not less than 1 mm, and the ratio of inner to outer diameter is 0.55 to 0.

95.

4. The adjustment method according to claim 3, characterized in that, The method for local adjustment of magnetic field strength of magnetic ring poles is applicable when the magnetic ring is made of permanent magnet material, with a coercivity of not less than 10 kOe and a magnetic energy product of not less than 10 MGOe.

5. The adjustment method according to claim 1, characterized in that, The uniformity of the magnetic field strength distribution of the magnetic ring poles is less than 2% after adjustment.

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