Bonded neodymium-iron-boron magnetic ring structure with anti-demagnetization capability and magnetizing method thereof

Abstract

The application relates to a bonded neodymium-iron-boron magnetic ring structure with anti-demagnetization capability and a magnetizing method thereof, and belongs to the field of permanent magnet motors. The outer diameter of the magnetic ring structure is circular, and the inner diameter of the magnetic ring structure is a variable curve, wherein the inner diameter thickness at the position of main magnetic poles is reduced, and the inner diameter thickness at the transition position between the main magnetic poles is increased; the magnetic ring structure adopts bonded neodymium-iron-boron material. The magnetic ring structure adopts a functionized inner diameter, can improve the anti-demagnetization capability of the magnetic ring under overload conditions, reduce irreversible magnetic flux loss, and solve the demagnetization problem. On the basis of the same outer diameter and the same height, the application can guarantee that almost equal amounts of bonded neodymium-iron-boron magnets are consumed as common magnetic rings, and cost is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to a bonded neodymium iron boron magnetic ring structure with anti-demagnetization capability and a magnetizing method thereof, in particular to a bonded neodymium iron boron ring-shaped magnet structure with anti-demagnetization capability and a matched multi-pole magnetizing mode, and belongs to the technical field of permanent magnet motors. BACKGROUND

[0002] Permanent magnet motors use permanent magnet materials as excitation sources, and these materials have high magnetic energy products and can provide stable magnetic fields, thereby improving the efficiency and power density of the motor. Currently, the magnetic materials used in permanent magnet motors have developed to the third generation of neodymium iron boron materials. Neodymium iron boron permanent magnet materials are widely used in various power electronic products due to their excellent performance.

[0003] As a kind of third-generation magnetic material, bonded neodymium iron boron permanent magnets are made by mixing neodymium iron boron powder with a binder and then forming. Bonded neodymium iron boron magnets combine the magnetic properties of high-performance neodymium iron boron materials and the flexibility of the bonding forming process, and can be manufactured into complex-shaped magnets through processes such as injection molding, compression molding and extrusion molding, etc. They have characteristics such as complex shape forming, multi-pole magnetization, high precision and good mechanical properties. Among them, the magnetic ring is a typical structure of bonded neodymium iron boron, which is particularly suitable for high-speed micro special motors in the fields of electronic products, automobile industry, medical equipment and industrial automation, etc.

[0004] In the application process of bonded neodymium iron boron, some problems have also been exposed. First, the coercivity and remanence of bonded neodymium iron boron are lower than those of sintered neodymium iron boron, so under the same conditions, bonded neodymium iron boron is more prone to irreversible loss of magnetic properties, i.e. demagnetization failure. The compact structure of high-speed micro special motors leads to significant temperature rise during operation, and the combined effect of temperature and current can easily cause irreversible demagnetization failure of bonded permanent magnets, thereby reducing the reliability and life of the motor.

[0005] At present, there is no good solution to the above problems. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a bonded neodymium iron boron magnetic ring structure with anti-demagnetization capability and a magnetizing method thereof, to overcome the problem of insufficient stability of the magnetic properties of permanent magnets in the prior art and the easy occurrence of demagnetization failure.

[0007] The present application adopts the following technical solutions:

[0008] A bonded neodymium iron boron magnetic ring structure with anti-demagnetization capability, the outer diameter of the magnetic ring structure is circular, and the inner diameter of the magnetic ring structure is a variable curve, wherein the inner diameter thickness at the position of the main magnetic pole is reduced, and the inner diameter thickness at the transition position between the main magnetic poles is increased;

[0009] The magnetic ring structure adopts bonded neodymium iron boron material.

[0010] Preferably, the inner diameter of the magnetic ring structure adopts a parameterized inner diameter, and the inner diameter function satisfies R=R2+H1cos(nθ).

[0011] Wherein, R is the inner diameter function; R2 is the circular inner diameter of the ordinary magnetic ring; H1 is an adjustment parameter, 0≤H1≤(R1-R2), R1 is the circular outer diameter of the ordinary magnetic ring; n is the number of magnetic poles, which is an even number; and θ represents an angle.

[0012] In the functionalized inner diameter, the position where the thickness of the magnetic ring decreases is the main magnetic pole position, and the position where the thickness of the magnetic ring increases is the transition position between the main magnetic poles. Increasing the thickness of the magnetic ring in the transition position improves the internal magnetic resistance of the permanent magnet, so that the internal magnetic field distribution of the permanent magnet at this position is more uniform when an external reverse magnetic field is applied, and local demagnetization is less likely to occur.

[0013] According to the present application, the finite element results show that the main magnetic pole position does not have obvious demagnetization failure, so in the functionalized inner diameter, the thickness of the transition position is increased, and the thickness of the main magnetic pole is decreased, which can ensure that the amount of magnetic material of the entire magnetic ring is consistent and reduce the cost.

[0014] The inner diameter of the magnetic ring structure of the present application adopts a functionalized shape to increase the anti-demagnetization ability of the position prone to demagnetization, and to reduce the irreversible loss of magnetic flux under the overload condition of the motor. The matching magnetizing fixture can position the anti-demagnetization magnetic ring and multi-pole magnetize it.

[0015] Preferably, in actual application, the value of H1 is too small, and the anti-demagnetization effect is not obvious, and H1 is too large, which will cause distortion of the magnetic wave form of the magnetic ring. The optimal value of the adjustment parameter H1 is determined by finite element simulation, and the demagnetization area of the permanent magnet should be controlled as small as possible to ensure the performance and stability of the motor, and the optimal value of H1 is that the newly added demagnetization area of the permanent magnet is not more than 2% to 5% of the surface area of the permanent magnet.

[0016] Preferably, during production, neodymium iron boron powder is mixed with a bonding agent to form a uniform mixture, and the magnetic ring structure of the present application can be quickly produced in batches through molding processes such as injection molding, pressing or extrusion by designing a corresponding mold;

[0017] Preferably, the bonding agent is epoxy resin or phenolic resin.

[0018] A magnetizing method based on the bonded neodymium iron boron magnetic ring structure with anti-demagnetization ability described above, which completes magnetization with the help of a magnetizing fixture, the magnetizing fixture comprising a positioning base, a magnetizing core, a winding and an upper cover, the magnetizing core is made of silicon steel sheet by lamination process, the winding is made of enameled copper wire, and the positioning base and the upper cover are made of non-magnetic materials such as nylon or aluminum alloy;

[0019] The magnetic ring structure is placed on the magnetizing core which is fixed, a magnetizing power supply is used to pass a transient pulse current to the winding for magnetization, and the magnetic ring structure is taken out after power-off to complete magnetization.

[0020] The multi-pole magnetizing clamp matched with the magnetic ring can magnetize the magnetic ring in the radial direction, and after magnetization, n magnetic poles are alternately distributed on the outer surface of the magnetic ring, and the number of magnetic poles is even.

[0021] Preferably, the positioning base is a circular structure, one side of which is provided with n positioning columns A around the periphery, and a magnetic ring positioning column B is arranged at the center, and the outer contour of the magnetic ring positioning column B is the same as the shape of the inner diameter of the magnetic ring structure.

[0022] The magnetizing core is a circular structure, which is provided with n positioning holes around the periphery for passing through the positioning columns A of the positioning base, and a through hole is arranged at the center for passing through the magnetic ring positioning column B of the positioning base; the magnetizing core is uniformly provided with n winding holes around the through hole for mounting the winding, and a magnetizing tooth part is formed between adjacent two winding holes, and the magnetizing tooth part corresponds to the main magnetic pole position of the magnetic ring structure during magnetization.

[0023] Preferably, the upper cover is a circular structure, which is provided with n limiting holes, and the positioning columns A of the positioning base pass through the positioning holes of the magnetizing core and the limiting holes of the upper cover in sequence to complete the assembly of the positioning base, the magnetizing core and the upper cover.

[0024] The functionized magnetic ring structure needs to accurately control the position of magnetization, so the positioning base provided with magnetic steel on the multi-pole magnetizing clamp is used to ensure that the magnetic ring with a functionized inner diameter can be fixed in the magnetizing clamp according to the position, so that the main magnetic pole position of the magnetic ring is aligned with the magnetization position of the magnetizing clamp, and the main magnetization position in the magnetization process is located in the middle of the magnetic pole.

[0025] The details of the present application can be referred to the prior art.

[0026] The present application has the following beneficial effects:

[0027] 1. The magnetic ring structure adopts a functionized inner diameter, which can improve the anti-demagnetization ability of the magnetic ring under overload conditions, reduce irreversible magnetic flux loss, and solve the demagnetization problem.

[0028] 2. The magnetic ring structure is different from the traditional method of reducing demagnetization by increasing thickness, and on the basis of the same outer diameter and the same height, the present application can ensure that the same amount of bonded neodymium iron boron magnet is consumed as ordinary magnetic rings, thereby saving costs.

[0029] 3. The multi-pole magnetizing clamp can position the magnetization position of the magnetic ring to ensure that the magnetization position cooperates with the functionized inner diameter. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification, the embodiments of the application, and their description, are to explain the application without imposing any undue limitations on the application.

[0031] Figure 1 The structure of the anti-demagnetization bonded Nd-Fe-B magnetic ring of the application is shown in the perspective view.

[0032] Figure 2 The structure of the anti-demagnetization bonded Nd-Fe-B magnetic ring of the application is shown in the front view.

[0033] Figure 3 The structure of the anti-demagnetization bonded Nd-Fe-B magnetic ring of the application is shown in the magnetizing schematic view.

[0034] Figure 4 The structure of the anti-demagnetization bonded Nd-Fe-B magnetic ring of the application is shown in the size schematic view, (a) is the R1, R1 schematic view, (b) is the H1 schematic view.

[0035] Figure 5 The magnetizing fixture assembly schematic view of the application is shown in the magnetizing fixture assembly schematic view.

[0036] Figure 6 The magnetizing core schematic view of the application is shown in the magnetizing core schematic view.

[0037] Figure 7 The positioning base schematic view of the application is shown in the positioning base schematic view.

[0038] Figure 8 The magnetizing fixture installation schematic view of the application is shown in the magnetizing fixture installation schematic view.

[0039] Figure 9 The winding diagram of the application is shown in the winding diagram.

[0040] Figure 10 The demagnetization rate distribution cloud map of the ordinary magnetic ring before and after demagnetization is shown in the demagnetization rate distribution cloud map.

[0041] Figure 11 The demagnetization rate distribution cloud map of the magnetic ring structure of the application before and after demagnetization is shown in the demagnetization rate distribution cloud map.

[0042] In the figure, 1 is the magnetic ring structure, 2 is the magnetizing core, 3 is the winding, 4 is the positioning base, 5 is the upper cover, 11 is the inner diameter cut-off part, 12 is the inner diameter thickened part, 21 is the positioning hole, 22 is the magnetizing tooth part, 41 is the positioning column A, 42 is the magnetic ring positioning column B, 231, 232, 233 and 234 are the winding holes. DETAILED DESCRIPTION

[0043] In order to make the person in the technical field better understand the technical solutions in the specification, the technical solutions in the embodiment of the specification are clearly and completely described below in combination with the drawings in the embodiment of the specification, but not limited to this, the invention is not described in detail, and it is according to the conventional technology in the field.

[0044] Embodiment 1

[0045] A bonded neodymium iron boron magnetic ring structure with anti-demagnetization capability, the outer diameter of the magnetic ring structure 1 is circular, and the inner diameter of the magnetic ring structure is a variable curve, wherein the inner diameter thickness at the position of the main magnetic pole is reduced, and the inner diameter thickness at the transition position between the main magnetic poles is increased.

[0046] The magnetic ring structure 1 adopts bonded neodymium iron boron material.

[0047] The inner diameter of the magnetic ring structure 1 adopts a parameterized inner diameter, and the inner diameter function satisfies R=R2+H1cos(nθ);

[0048] Wherein, R is the inner diameter function; R2 is the circular inner diameter of the ordinary magnetic ring; H1 is an adjustment parameter, 0≤H1≤(R1-R2), R1 is the circular outer diameter of the ordinary magnetic ring; θ represents the angle; n is the number of magnetic poles, which is an even number, in this embodiment, n=4, as shown in Figure 1 Figure 4 The position 11 is the part of the functionized inner diameter, which is the main magnetic pole position, and the position 12 is the part of the functionized inner diameter, which is the transition position between the adjacent two magnetic poles.

[0049] In the functionized inner diameter, the position of the reduced magnetic ring thickness is the main magnetic pole position, and the position of the increased magnetic ring thickness is the transition position between the main magnetic poles. Increasing the thickness of the transition zone of the magnetic ring improves the internal magnetic resistance of the permanent magnet, so that the internal magnetic field distribution of the permanent magnet at this position is more uniform when an external reverse magnetic field is applied, and local demagnetization is less likely to occur.

[0050] According to the application, the finite element results show that the main magnetic pole position will not have obvious demagnetization failure, so in the functionized inner diameter, the thickness of the transition position is increased, and the thickness of the main magnetic pole is reduced, so that the amount of magnetic material of the whole magnetic ring can be ensured to be consistent, and the cost is reduced.

[0051] The inner diameter of the magnetic ring structure of the application adopts a functionized shape to increase the anti-demagnetization capability of the easy demagnetization position, reduce the irreversible loss of magnetic flux under the overload condition of the motor, and the matching magnetizing fixture can position the anti-demagnetization magnetic ring and multi-pole magnetize.

[0052] As Figure 5 ​As shown, R1 is the outer diameter of the ordinary magnetic ring, R2 is the inner diameter of the ordinary magnetic ring, H1 is the adjustment parameter, H2 is the thickness of the main magnetic pole, and H1+H2=R1-R2.

[0053] In practical applications, if the value of H1 is too small, the anti-demagnetization effect is not obvious; if H1 is too large, it will cause distortion of the surface magnetic waveform of the magnetic ring. The optimal value of parameter H1 is determined through finite element simulation. The demagnetization area of ​​the permanent magnet should be controlled within a very small range to ensure the performance and stability of the motor. The optimal value of H1 is such that the newly added demagnetization area of ​​the permanent magnet does not exceed 2% to 5% of its surface area. In this embodiment, R1 = 13mm, and the inner diameter R2 = 9mm. According to the parameterized inner diameter function R = R2 + H1cos(nθ) of the present invention, the inner diameter R = 9 + H1cos(4θ), where 0 ≤ H1 ≤ 4. Through finite element analysis, H1 = 1mm is selected. At this point, the demagnetization area reaches its minimum value, and there is no obvious continuing trend with the increase of H1, and the surface magnetic waveform does not show obvious distortion.

[0054] Example 2

[0055] A bonded NdFeB magnetic ring structure with anti-demagnetization capability is described in Example 1. The difference is that, during manufacturing, NdFeB powder is mixed with binders such as epoxy resin and phenolic resin to form a uniform mixture, which is then formed by injection molding, pressing or extrusion. The magnetic ring structure of the present invention can be mass-produced quickly by designing molds with corresponding structures.

[0056] Example 3

[0057] A magnetization method for a bonded NdFeB magnetic ring structure with anti-demagnetization capability based on Embodiment 1 is provided. Magnetization is completed by means of a magnetization fixture. The magnetization fixture includes a positioning base 4, a magnetizing core 2, a winding 3 and a top cover 5. The magnetizing core 2 is made of silicon steel sheet lamination process, the winding 3 is made of enameled copper wire, and the positioning base 4 and the top cover 5 are made of non-magnetic materials such as nylon or aluminum alloy.

[0058] The magnetic ring structure 1 is placed on the magnetizing core 2 and fixed to prevent rotation caused by the interaction of magnetic fields during magnetization. A momentary pulse current is applied to the winding using a magnetizing power supply to magnetize it. After the power is turned off, the magnetic ring structure is removed to complete the magnetization.

[0059] The multi-pole magnetizing fixture adapted to the magnetic ring can magnetize the magnetic ring radially in multiple poles. After magnetization, four magnetic poles are alternately distributed on the outer surface of the magnetic ring, and the number of magnetic poles is even.

[0060] like Figure 7 As shown, the positioning base 4 is a circular structure with four positioning posts A41 around one side and a magnetic ring positioning post B42 in the center. The outer contour of the magnetic ring positioning post B42 is the same as the inner diameter of the magnetic ring structure 1.

[0061] As Figure 6 , the magnetized core 2 is a circular structure, and four positioning holes 21 are arranged around the circumference of the magnetized core 2, which are used to pass through the positioning column A41 of the positioning base, and a through hole is arranged at the center of the magnetized core 2, which is used to pass through the magnetic ring positioning column B 42 of the positioning base; the magnetized core 2 is uniformly provided with four winding holes 231, 232, 233 and 234 around the through hole, which are used to install windings, as Figure 9 , the winding mode of the four-pole magnetized core is shown, the winding is single-phase, and two connection terminals are connected to the positive and negative poles of the pulse power, respectively, and the winding direction of adjacent teeth is opposite, so that the magnetic poles are alternately distributed.

[0062] The two adjacent winding holes form a magnetizing tooth part 22, and the magnetizing tooth part 22 corresponds to the main magnetic pole position of the magnetic ring structure during magnetization.

[0063] As Figure 5 , the upper cover 5 is a circular structure, and four limiting holes are arranged on the upper cover 5, the positioning column A41 of the positioning base passes through the positioning hole of the magnetized core and the limiting hole of the upper cover in sequence, and the assembly of the positioning base, the magnetized core and the upper cover is completed.

[0064] The function of the magnetic ring structure of the application needs to be accurately controlled during magnetization, so the positioning base of the magnetic steel is arranged on the multi-pole magnetizing clamp to ensure that the magnetic ring with a function of the inner diameter can be fixed in the magnetizing clamp according to the position, so that the main magnetic pole position of the magnetic ring is aligned with the magnetizing position of the magnetizing clamp, and the main magnetization position in the magnetization process is located in the magnetic pole.

[0065] The demagnetization results of the bonded neodymium iron boron magnetic ring structure with anti-demagnetization ability of the application and the ordinary magnetic ring are analyzed. As Figure 10 , the demagnetization rate distribution cloud diagram of the ordinary four-pole magnetic ring after the motor is overloaded, Figure 11 , the demagnetization rate distribution cloud diagram of the four-pole anti-demagnetization magnetic ring of the application. The demagnetization ratio of 0 represents that the position has not occurred irreversible demagnetization, and the demagnetization ratio of 100 indicates that the position has been completely demagnetized. From Figure 10 , it can be observed that the magnetic ring under normal circumstances has four positions with small demagnetization area (red area in the figure), and the four positions are located in the transition zone between the main magnetic poles. In the multi-pole magnetic ring, there must be a magnetic pole transition area between the magnetic poles, which cannot be avoided. By comparing Figure 10 and Figure 11 , it can be found that the newly added demagnetization area of the bonded neodymium iron boron magnetic ring structure with anti-demagnetization ability of the application is obviously lower than that of the ordinary magnetic ring after overload, and the application has obvious anti-demagnetization advantage.

[0066] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles described in the present application, can also be made several improvements and refinements, these improvements and refinements should also be considered the scope of protection of the present application.

Claims

1. A bonded neodymium-iron-boron magnetic ring structure having anti-demagnetization capability, characterized in that, The outer diameter of the magnetic ring structure is circular, and the inner diameter of the magnetic ring structure is a variable curve, wherein the inner diameter thickness at the position of the main magnetic pole is reduced, and the inner diameter thickness at the transition position between the main magnetic poles is increased; The magnetic ring structure adopts bonded neodymium iron boron material; The inner diameter function of the magnetic ring structure satisfies R=R2+H1cos(nθ); R is the inner diameter function; R2 is the circular inner diameter of the ordinary magnetic ring; H1 is an adjustment parameter, 0≤H1≤(R1-R2), R1 is the circular outer diameter of the ordinary magnetic ring; n is the number of magnetic poles, which is an even number; θ represents an angle; H1 is determined by finite element simulation to achieve an optimal solution, so that the newly added demagnetization area does not exceed 5%.

2. The bonded Nd-Fe-B ring structure with anti-demagnetization capability according to claim 1, characterized in that, In the production, the neodymium iron boron powder is mixed with a binder to form a uniform mixture, and the mixture is formed by injection molding, pressing or extrusion process; The binder is, for example, epoxy resin or phenolic resin.

3. A method of magnetizing the bonded neodymium-iron-boron magnetic ring structure with anti-demagnetization capability according to claim 2, characterized in that, The magnetizing fixture includes a positioning base, a magnetizing core, a winding and an upper cover, the magnetizing core is made of silicon steel sheet by lamination process, the winding is made of enameled copper wire, and the positioning base and the upper cover are made of non-magnetic material; The magnetic ring structure is placed on the magnetizing core and fixed, a magnetizing power source is used to pass a transient pulse current to the winding for magnetizing, and the magnetic ring structure is taken out after power-off to complete magnetizing; The positioning base is a circular structure, one side of which is provided with n positioning columns A around the periphery, and a magnetic ring positioning column B is arranged at the center, and the outer contour of the magnetic ring positioning column B is the same as the shape of the inner diameter of the magnetic ring structure; The magnetizing core is a circular structure, which is provided with n positioning holes around the periphery for passing the positioning columns A of the positioning base, and a through hole is arranged at the center for passing the magnetic ring positioning column B of the positioning base; the magnetizing core is uniformly provided with n winding holes around the through hole for installing the winding, and a magnetizing tooth part is formed between the adjacent two winding holes, and the magnetizing tooth part corresponds to the position of the main magnetic pole of the magnetic ring structure during magnetizing.

4. The method of magnetizing a bonded Nd-Fe-B ring structure with anti-demagnetization capability according to claim 3, characterized in that, The upper cover is a circular structure, which is provided with n limiting holes, and the positioning columns A of the positioning base pass through the positioning holes of the magnetizing core and the limiting holes of the upper cover in sequence to complete the assembly of the positioning base, the magnetizing core and the upper cover.

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