Magnet assembly and preparation method and application thereof

Abstract

The invention discloses a magnet assembly and a preparation method and application thereof, the magnet assembly at least comprises two magnet units, and two adjacent magnet units have different magnetization directions; a welding point exists between every two adjacent magnet units; each magnet unit can be provided with a plating layer or not on the combination surface of two adjacent magnet units, and the plating layer contains other elements except Nd, Fe and B. The magnet unit is characterized in that the combination surface of the magnet unit and the two adjacent magnet units can be provided with a plating layer or not provided with a plating layer. According to the magnet assembly, on the premise that the Halbach array mode of magnet arrangement is not changed, the connection strength of the magnet structure and / or the stability in severe environments such as high temperature and high humidity are / is remarkably improved, and unnecessary loss of magnet performance is avoided. In addition, the preparation method of the magnet assembly also remarkably improves the assembly efficiency of the magnet assembly, and can be widely applied to large-scale production.

Description

Technical Field

[0001] The present invention belongs to the field of magnet structure, and relates to a magnet assembly and a preparation method and application thereof, and in particular to a magnet assembly having at least two magnet units, and a preparation method and application thereof. Background Art

[0002] A magnet assembly is usually assembled from several magnets to form a specific magnetic field distribution. In traditional magnet assemblies, the arrangement and combination of magnets are often limited by material properties and magnetic field design, which to a certain extent limits the optimization and application scope of the magnetic field. Halbach Array is a special magnet structure that is widely regarded as a magnet layout close to the ideal state in engineering applications. This array is designed to generate a stronger and more effective magnetic field with magnet units of the same area. In current technical practice, three magnets with magnetic repulsion properties are usually glued together by adhesive to form the required magnet structure. However, this method of bonding by adhesive has a significant disadvantage, that is, the connection strength of the bonding point is relatively low. Therefore, in harsh environments such as high temperature and high humidity, these bonding points are prone to debonding and breaking. Especially in some application scenarios with high requirements for wet heat testing, such as mobile phone cameras, the shortcomings of this bonding method are particularly prominent. Since devices such as mobile phone cameras are frequently exposed to various complex environmental conditions during use, the stability and reliability of the magnets are extremely high. If the magnet structure begins to debond or break under these conditions, it will directly affect the performance and service life of the device.

[0003] Although there have been reports proposing the use of welding to fix magnets, this method also faces many challenges in practical applications. For example, the high temperature during welding may cause changes in the internal structure of the magnet, thereby reducing its magnetic properties. Moreover, the stress generated during welding may cause microcracks in the magnet, which may expand during long-term use and eventually lead to the failure of the magnet. Moreover, if a low-melting-point metal solder is heated and melted, and then infiltrated and filled into the gap between the magnets to achieve connection between the magnets, the introduction of the low-melting-point metal will affect the flatness of the precision device, thereby affecting the performance of the entire device. In addition, even if laser welding is used, the following problems are still faced: ① Halbach magnet components are usually bonded together by gluing, and then further fixed by welding. In actual operation, due to the high requirements of laser welding on the surface cleanliness of the magnet component, after the magnet is glued, there will be glue overflow at the position where welding is required, so it is necessary to remove the glue to ensure that the surface of the magnet component is clean before welding, which reduces the efficiency of assembly. ② The temperature of the laser welder is relatively high, reaching up to 600-3000°C, which may lead to increased magnetic loss for temperature-sensitive NdFeB magnets.

[0004] Therefore, how to improve the connection strength of the magnet structure, especially the stability in harsh environments such as high temperature and high humidity, as well as avoid excessive loss of magnet performance and improve assembly efficiency, has become a technical direction that urgently needs to be improved in this field. Summary of the invention

[0005] In order to improve the above problems, the present invention provides a magnet assembly, which includes at least two magnet units, wherein:

[0006] Two adjacent magnet units have different magnetization directions;

[0007] There is a welding point between two adjacent magnet units; and

[0008] The weld has at least one feature selected from the following:

[0009] (1) The welding point is located between the gaps of the end faces of the two adjacent magnet units, preferably the welding point is located between the gaps of the weak magnetic surfaces of the two adjacent magnet units;

[0010] (2) The magnetic flux attenuation rate of the magnet assembly before and after welding is ≤5%.

[0011] According to an embodiment of the present invention, the magnetic flux attenuation rate of the magnet assembly before and after welding is ≤4%, for example: 1%, 2%, 3%, 4%.

[0012] According to an embodiment of the present invention, in the magnet assembly, two adjacent magnet units have different magnetization directions. Preferably, the magnetization directions of the two magnet units on both sides of any magnet unit are opposite. Preferably, the magnet units in the magnet assembly are arranged in the order of a Halbach Array.

[0013] According to the embodiment of the present invention, there is no particular limitation on the shape of the welding point. For example, the shape of the welding point can be circular, oval, square, rectangular, quasi-circular, quasi-oval, quasi-square, quasi-rectangular, etc. Those skilled in the art should understand that the shape of the welding point can be selected according to the welding process and the structure of the magnet unit to ensure the strength and stability of the welding point. For example, a quasi-circular welding point can provide uniform stress distribution, while a quasi-oval welding point can provide better strength in certain directions. Quasi-square or quasi-rectangular welding points are suitable for occasions requiring a larger contact area.

[0014] According to an embodiment of the present invention, the magnet unit refers to an independent magnet. Specifically, the magnet unit can be a magnetic material with a specific geometric shape, such as a cylindrical, rectangular, annular or any other shape suitable for the target application scenario. The size and shape of the magnet unit can be optimized according to the final use of the magnet assembly to achieve the expected magnetic properties and mechanical strength. For example, for applications requiring high magnetic field strength, a larger magnet unit can be used; while for applications requiring a compact design, a smaller magnet unit may be selected. In an embodiment of the present invention, a neodymium iron boron permanent magnet can be used as a magnet unit.

[0015] According to an embodiment of the present invention, the welding point is located at the gap between the end faces of two adjacent magnet units, which are closely adjacent to each other to ensure that the welding point can effectively connect the two magnet units. Preferably, the welding point is located at the gap between the weak magnetic surfaces of two adjacent magnet units, which refers to the relatively weak magnetic parts of the magnet units. By welding between these gaps, it can be ensured that the connection between the magnet units is both firm and stable, thereby improving the reliability and performance of the overall structure.

[0016] According to an embodiment of the present invention, the number Q of welding points between two adjacent magnet units can be any integer between 1 and 6. For example, the number of welding points can be 1, 2, 3, 4, 5 or 6. Furthermore, the total number Q of welding points of the magnet assembly can satisfy the following relationship: (n-1)≤Q≤6*(n-1), preferably, 2*(n-1)≤Q≤3*(n-1); wherein: n is the number of magnet units. The inventors have found through a large number of experiments that if the number of welding points is too large, the magnetic flux of the magnet assembly will be greatly reduced. And too many welding points may also cause the decay phenomenon of the magnetic circuit to become more serious, so that the magnetic properties of the magnet assembly will gradually decrease after long-term use or in a high temperature environment.

[0017] According to an embodiment of the present invention, the equivalent spherical diameter R (ESD) of at least one or all of the welding points is less than 1 mm, preferably less than 0.8 mm, for example, 0.1 mm to 1 mm, preferably 0.1 mm to 0.3 mm, such as 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm or 0.8 mm.

[0018] According to an embodiment of the present invention, the length L of any welding point between two adjacent magnet units is q The following relationship can be satisfied: 5%*L≤L q ≤40%*L, preferably, 6%*L≤L q ≤20%*L; wherein L is the average value of the sum of the lengths of the two adjacent magnet units in a direction parallel to the contact surface between the two adjacent magnet units.

[0019] According to an embodiment of the present invention, the total length L of the welding point between two adjacent magnet units is Q Satisfies the following relationship: 10%*L≤L Q ≤80%*L, preferably, 12%*L≤L Q ≤50%*L; wherein: L is the average value of the sum of the lengths of the two adjacent magnet units in a direction parallel to the contact surface between the two adjacent magnet units.

[0020] The inventor has found through a large number of experiments that if the length of the welding point is too long, it is easy to cause marginal effects, such as uneven heat distribution, too high or too low temperature at the edge of the weld, which will cause cracks, pores or other defects in the weld, thereby affecting the strength and reliability of the entire welded structure. The present invention controls the length and size of the welding point within the above range, while ensuring excellent welding strength and maintaining excellent magnetic flux in the welded magnet assembly.

[0021] According to an embodiment of the present invention, the minimum distance S between the outer peripheral edge of the welding point and the surface of the magnet unit is q ≥1mm; preferably, 5%*L≤S q <50%*L. Preferably, the distance S between the outer peripheral edge of the welding point and the center of the contact surface between the two adjacent magnet units is c Satisfy the following relationship: 15%*L≤S c <50%*L; preferably, 25%*L≤S c <50%*L. The inventor unexpectedly discovered through a large number of experiments that if Sc≤15%*L, the distance between the welding point and the center of the contact surface between the two adjacent magnet units is too small, which will significantly reduce the magnetic flux of the magnet assembly.

[0022] According to an embodiment of the present invention, the depth D of the welding point toward the contact surface between the two adjacent magnet units is q Satisfies the following relationship: D q ≤H*50%, preferably, H*5%≤D q ≤H*30%; wherein: H is the minimum value of the lengths of the two magnet units in the direction parallel to the contact surface between the two adjacent magnet units.

[0023] According to an embodiment of the present invention, a bonding layer may be provided between the two adjacent magnet units, so that the magnet assembly is simply fixed first and then further welded. Preferably, the thickness of the bonding layer is 0.01-0.1 mm. For example, the bonding layer is prepared by glue, adhesive, etc.

[0024] According to an embodiment of the present invention, the magnet assembly comprises at least two magnet units, wherein:

[0025] Two adjacent magnet units have different magnetization directions;

[0026] There is a welding point between two adjacent magnet units; and the welding point includes Nd, Fe and B elements and other elements except Nd, Fe and B elements.

[0027] According to an embodiment of the present invention, the welding point may have the features described above.

[0028] According to an embodiment of the present invention, the magnet unit may have a coating (also referred to as a "white sheet" in the industry) or may not have a coating (also referred to as a "black sheet" in the industry) on the bonding surface with two adjacent magnet units, and the coating contains elements other than Nd, Fe and B.

[0029] According to an embodiment of the present invention, the elements other than Nd, Fe and B are selected from one, two or more of Ni, Zn, Cu, P, Mo and the like.

[0030] According to an embodiment of the present invention, the coating is a metal coating. The present invention is not limited to the type of the metal coating, for example, it can be a Ni coating, a Zn coating, a Ni-Cu-Ni coating, a Cu-Ni coating or a Zn-Ni coating.

[0031] According to an embodiment of the present invention, the thickness of the coating may be 1 to 30 μm, for example 2 to 25 μm, preferably 5 to 20 μm, more preferably 8 to 15 μm, exemplified by 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm.

[0032] According to an embodiment of the present invention, the magnet units may or may not optionally include a bonding layer such as glue or adhesive, except for the welding points. When the bonding layer is included, the thickness of the bonding layer is 0.01-0.1 mm. For example, the glue or adhesive used in the bonding layer may be a material known in the art, such as one or more selected from epoxy resin, polyurethane, silicone, AB glue, and anaerobic glue.

[0033] According to an embodiment of the present invention, before two adjacent magnet units are combined by welding points, the magnet units can be optionally magnetized magnet units or unmagnetized magnet units. Preferably, the magnetized magnet units can be combined by welding, or the welded magnet units can be magnetized. It should be understood that the magnetization should make the magnet units have the magnetization direction as described above, such as the magnetization direction sequence of the Halbach Array. Preferably, the magnetization can be obliquely magnetized along the edge of the magnet assembly.

[0034] According to an embodiment of the present invention, before two adjacent magnet units are joined by welding points, the magnet units may be diffused magnets or undiffused magnets. Preferably, the magnet units may be diffused first and then welded.

[0035] According to an embodiment of the present invention, the magnetic properties of two adjacent magnet units may be the same or different. As an example, in the magnet assembly, the central magnet unit has a higher Hcj than other magnet units. More preferably, in the magnet assembly, the Hcj of the magnet unit gradually decreases from the central magnet unit to the magnet units on both sides. Or, as an example, in the magnet assembly, the central magnet unit has a lower Hcj than other magnet units. More preferably, in the magnet assembly, the Hcj of the magnet unit gradually increases from the central magnet unit to the magnet units on both sides.

[0036] According to an embodiment of the present invention, the magnet unit may or may not have a chamfer. Preferably, the magnets whose weak magnetic surfaces are adjacent to each other in the magnet assembly are chamfered. Preferably, the chamfer is an R-shaped chamfer. For example, R is 0.1-0.3 mm.

[0037] According to an embodiment of the present invention, the magnet unit may be selected from neodymium iron boron magnets.

[0038] The present invention also provides a method for preparing the magnet assembly, which comprises combining the two adjacent magnet units by welding at welding points.

[0039] According to the embodiment of the present invention, the specific method of welding is not limited, that is, all welded magnet assemblies having characteristic points (1) to (9) have reliable welding strength and an acceptable magnetic flux reduction range of the magnet assembly. Preferably, the welding method can be laser welding. Exemplarily, the laser welding can be pulse welding, such as using QCW (Quasi-Continuous Wave) laser welding. For example, the pulse width of the laser welding is 50-150ms, exemplified by 50ms, 60ms, 70ms, 80ms, 90ms, 100ms, 110ms, 120ms, 130ms, 140ms, and 150ms; the frequency is 50-350Hz, preferably 100-300Hz, exemplified by 50Hz, 100Hz, 120Hz, 150Hz, 180Hz, 200Hz, 240Hz, 300Hz, and 350Hz; the peak power is 10-40%, exemplified by 10%, 15%, 18%, 20%, 25%, 30%, 35%, and 40%.

[0040] According to an embodiment of the present invention, in the method for preparing the magnet assembly, before two adjacent magnet units are welded together by welding points, the magnet units can be optionally magnetized magnet units or unmagnetized magnet units. Preferably, the magnetized magnet units can be welded together, or the welded magnet units can be magnetized.

[0041] According to an exemplary embodiment of the present invention, the method for preparing the magnet assembly comprises the following steps:

[0042] S1: Preparation of magnet unit;

[0043] S2: magnetizing the magnet unit and arranging the magnets according to assembly requirements to form a magnet assembly; optionally, placing the magnet assembly in a fixing fixture;

[0044] S3: Dispense glue on the magnet assembly, and then press and solidify it;

[0045] S4: Laser welding is performed along the end face joints of adjacent magnets or the weak magnetic surface joints of magnets.

[0046] According to an exemplary embodiment of the present invention, the method for preparing the magnet assembly comprises the following steps:

[0047] S1: Preparation of magnet unit;

[0048] S2: Arranging magnets in the magnet unit according to assembly requirements to form a magnet assembly; optionally, placing the magnet assembly in a fixing fixture;

[0049] S3: Dispense glue on the magnet assembly, and then press and solidify it;

[0050] S4: magnetizing the magnet assembly according to the polarity direction requirements;

[0051] S5: Laser welding is performed along the end face joints of adjacent magnets or the weak magnetic surface joints of magnets.

[0052] In one embodiment of the present invention, the order of steps S4 and S5 may be exchanged.

[0053] In one embodiment of the present invention, step S3 may also be omitted.

[0054] In one embodiment of the present invention, the method for preparing the magnet assembly further comprises performing surface treatment on the magnet unit obtained in step S1 to obtain a coating. Preferably, the coating is a metal coating, such as a Ni coating, a Zn coating, a Ni-Cu-Ni coating, a Cu-Ni coating or a Zn-Ni coating. During laser welding, laser welding is performed along the coating at the end face joints of adjacent magnets or the coating at the weak magnetic surface joints of the magnets.

[0055] In one embodiment of the present invention, the curing temperature is 40-150°C, exemplified by 40°C, 60°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and 150°C; the curing time is 15-60min, exemplified by 15min, 20min, 30min, 40min, 50min, and 60min.

[0056] In one embodiment of the present invention, the method for preparing the magnet assembly may further include, during welding, using a cover plate tooling having holes or tracks that are exactly the same as the welding points to accurately position the welding equipment at the welding position for welding.

[0057] In one embodiment of the present invention, the method for preparing the magnet assembly may further include using a visual detector to accurately locate the joints of the magnet units to achieve precise laser welding, thereby minimizing the magnetic flux loss of the magnet assembly.

[0058] The present invention also provides a motor, comprising the magnet assembly.

[0059] According to an embodiment of the present invention, the motor is a linear motor. For example, the motor includes a stator assembly and a moving assembly. Preferably, the stator assembly is fixedly mounted on the device, and the moving assembly can move along a linear direction on the stator assembly. The stator assembly and the moving assembly interact with each other through magnetic force to achieve contactless driving.

[0060] According to an embodiment of the present invention, the motor further comprises a control system, which can be integrated with the control system of the magnetic attraction component to achieve precise synchronous control, thereby improving the performance of the motor.

[0061] According to an embodiment of the present invention, the motor further comprises a driving device, and the driving device and the magnet assembly are respectively arranged in the stator assembly and the moving assembly.

[0062] The present invention also provides a photographing or video recording device, the photographing or video recording device comprises the above motor. As an example, the photographing or video recording device further comprises an optical element and a photosensitive element.

[0063] The present invention also provides an electronic device, comprising the above motor.

[0064] According to an embodiment of the present invention, the electronic device further comprises a housing, and the photographing or video recording device is arranged on the housing.

[0065] Beneficial effects:

[0066] The magnet assembly of the present invention overcomes the repulsive force between magnets by welding, and significantly improves the connection strength of the magnet structure and / or the stability in harsh environments such as high temperature and high humidity without changing the arrangement of the magnets, so that the magnet assembly is not easily debonded due to the decrease in bonding force in the high temperature and high humidity environment, thereby avoiding unnecessary loss of magnet performance. In addition, the preparation method of the magnet assembly of the present invention also significantly improves the assembly efficiency of the magnet assembly, and can be widely used in large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 Schematic diagram of the welding points of the weak magnetic surface of the Halbach magnet assembly in Example 1.

[0068] Figure 2 Schematic diagram of the strong magnetic surface of the Halbach magnet assembly of comparative example 1.

[0069] Figure 3 for Figure 1 The top view is the weak magnetic surface of the Halbach magnet assembly in Example 1.

[0070] Figure 4 for Figure 1 The front view is the front view of the Halbach magnet assembly of Example 1.

[0071] Figure 5 It is a left side view of the Halbach magnet unit of Example 1.

[0072] Figure 6 A schematic diagram of the structure of the fixed bracket.

[0073] Figure 7 A schematic diagram of the structure of the fixed bracket.

[0074] Figure 8 Schematic diagram of the welding points of the weak magnetic surface of the Halbach magnet assembly in Example 6.

[0075] Fig. 9 Schematic diagram of the welding points of the weak magnetic surface of the Halbach magnet assembly in Example 9. DETAILED DESCRIPTION

[0076] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0077] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0078] Reference Figure 1-5 , a magnet assembly, the magnet assembly comprising at least two magnet units, wherein:

[0079] Two adjacent magnet units have different magnetization directions, and the magnetization directions of the two magnet units on both sides of any magnet unit are opposite. Preferably, the magnet units in the magnet assembly are arranged in the order of the Halbach array.

[0080] There is a welding point between two adjacent magnet units; and the welding point has at least one feature selected from the following:

[0081] (1) The welding point is located between the gaps between the end faces of two adjacent magnet units;

[0082] (2) The magnetic flux attenuation rate of the magnet assembly before and after welding is ≤5%.

[0083]

Number of welding points q

[0084] The number q of welding points between two adjacent magnet units is any integer between 1 and 6.

[0085]

Total number of welding points Q

[0086] The total number Q of welding points of the magnet assembly satisfies the following relationship: (n-1)≤Q≤4*(n-1), where n is the number of magnet units; preferably, 2*(n-1)≤Q≤3*(n-1).

[0087]

Equivalent circle diameter R of welding point

[0088] The equivalent circle diameter R of at least one or all of the welding points is less than 1 mm; preferably, the equivalent circle diameter R of all welding points is less than 0.8 mm; for example, the equivalent circle diameter R of all welding points is 0.1 mm to 1 mm, preferably 0.1 mm to 0.3 mm.

[0089]

Welding point length L q

[0090] The length L of any welding point between two adjacent magnet units q Satisfies the following relationship: 5%*L≤L q ≤40%*L, where L is the average value of the sum of the lengths of two adjacent magnet units in the direction parallel to the contact surface between the two adjacent magnet units. Preferably, 6%*L≤L q ≤20%*L.

[0091]

Total length of welding point L Q

[0092] The total length L of the welding point between two adjacent magnet units Q Satisfies the following relationship: 10%*L≤L Q ≤80%*L, where L is the average value of the sum of the lengths of two adjacent magnet units in the direction parallel to the contact surface between the two adjacent magnet units; preferably, 12%*L≤L Q ≤40%*L.

[0093]

The minimum distance S between the outer edge of the welding point and the surface of the magnet unit q

[0094] The minimum distance S between the outer edge of the welding point and the surface of the magnet unit q ≥1mm; preferably, 5%*L≤S q <50%*L.

[0095] Preferably, the distance S between the outer peripheral edge of the welding point and the center of the contact surface between two adjacent magnet units is c Satisfy the following relationship: 15%*L≤S c <50%*L; preferably, 25%*L≤S c <50%*L;

[0096]

The depth D of the welding point toward the contact surface between two adjacent magnet units q

[0097] The depth D of the welding point toward the contact surface between two adjacent magnet units q Satisfies the following relationship: D q ≤H*50%, preferably, H*5%≤D q ≤H*30%; wherein: H is the minimum value of the lengths of two magnet units in a direction parallel to the contact surface between the two adjacent magnet units.

[0098] [Shape of welding point]

[0099] The shape of the welding point can be circular, oval, square, rectangular, quasi-circular, quasi-oval, quasi-square, quasi-rectangular, etc.

[0100]

Composition of welding points

[0101] A welding point exists between two adjacent magnet units; and the welding point includes Nd, Fe, and B elements and other elements except Nd, Fe, and B elements.

[0102] Preferably, the magnet unit may have a coating on the bonding surface with two adjacent magnet units, or may not have a coating, and the coating contains elements other than Nd, Fe and B elements.

[0103] Preferably, the elements other than Nd, Fe and B are selected from one, two or more of Ni, Zn, Cu, P, Mo and the like.

[0104] Preferably, the coating is a metal coating, for example, a Ni coating, a Zn coating, a Ni-Cu-Ni coating, a Cu-Ni coating or a Zn-Ni coating.

[0105] Preferably, the thickness of the coating may be 1 to 30 μm, for example, 2 to 25 μm, preferably 5 to 20 μm, and more preferably 8 to 15 μm.

[0106]

Adhesive layer

[0107] In addition to the welding points, the magnet units may or may not optionally include a bonding layer such as glue or adhesive. For example, the glue or adhesive used in the bonding layer is selected from one or more of epoxy resin, polyurethane, silicone, AB glue and anaerobic glue.

[0108]

Magnet unit

[0109] Before two adjacent magnet units are connected via a welding point, the magnet units can be optionally magnetized magnet units or unmagnetized magnet units.

[0110] The magnet unit may be a neodymium iron boron magnet, for example, a 48H sintered neodymium iron boron magnet.

[0111] Preferably, the magnetized magnet units can be combined by welding, or the welded magnet units can be magnetized.

[0112] Preparation Example 1: Preparation of magnet unit

[0113] The following Examples 1-11 and Comparative Examples 1-4 all use 48H sintered NdFeB magnets, which are cut into magnet units of the following sizes: 15mm*5mm*0.9mm, and the side with the largest area is selected as the welding contact surface, that is, the corresponding welding contact surfaces are 15mm*5mm, respectively, and the length L of the magnet unit is 15mm, the width W is 5mm, and the height H is 0.9mm.

[0114] Example 1

[0115] A method for preparing a magnet assembly, comprising treating the magnet unit of Preparation Example 1 as follows:

[0116] S1: Prepare NdFeB magnet matrix in the same manner as in Preparation Example 1, and obtain 30 magnet units of 15 mm*5 mm*0.9 mm;

[0117] S2: Place three NdFeB magnet units in a fixed fixture and arrange them according to the Halbach magnetization method to prepare 10 Halbach magnet assemblies. The fixed fixture is a metal slot fixture with a thickness of 3 mm ( Figure 6 );

[0118] S3: Dispense glue on the magnet assembly, and then press and solidify it;

[0119] Use glue dispensing equipment to dispense epoxy glue (F-44 phenolic epoxy resin) on the adjacent surface of the magnetized NdFeB magnet units; use a transverse pressing device to press the three NdFeB magnet units together; put the pressed Halbach magnet assembly into the oven for curing, and heat it at 100°C for 40 minutes; the average thickness of the cured glue layer is 0.04mm. For the cured Halbach magnet assembly, randomly select 10 pieces, measure the magnetic flux and find the average value, recorded as M1; measure the shear force and find the average value, recorded as N1.

[0120] S4: For the 10 magnet assemblies in step S3, the weak magnetic surface of the Hailbeck magnet assembly (such as Figure 1 Laser welding is performed at the joints of S14 and S24 shown in the figure. The magnetic flux of the magnet assembly after welding is measured and the average value is recorded as M2; the shear force is measured and the average value is recorded as N1. The magnetic flux attenuation rate before and after welding is calculated as (M1-M2) / M1*100%, and the shear force enhancement ratio is calculated as (N1-N2) / N1*100%.

[0121] The specific welding parameters are shown in Table 1, and the characteristic parameters of the formed welding points are shown in Table 2.

[0122] Embodiment 2-5

[0123] The same process steps as those in Example 1 are used, except that: between steps S1 and S2, step S11 is further included: the magnet unit is subjected to surface treatment to obtain a metal coating, and the specific coating composition and thickness are shown in Table 1. The thickness of the coating is obtained by randomly selecting 3 points on the coating surface of each magnet unit in the 30 magnet units for thickness measurement, and calculating the average value of the thickness values ​​of the 90 points.

[0124] Embodiment 6-8

[0125] The same process steps as those in Example 2 are used, except that: Step S2: five NdFeB magnet units are placed in a fixing fixture, arranged and magnetized according to the Halbach magnetization method, to prepare a Halbach magnet assembly.

[0126] Example 9

[0127] The magnet unit of Preparation Example 1 was processed as follows:

[0128] S1: Prepare a NdFeB magnet matrix in the same manner as in Preparation Example 1 to obtain a magnet unit of 15 mm*5 mm*0.9 mm;

[0129] S2: placing two NdFeB magnet units in a fixed fixture, arranging them in a parallel magnetization manner for magnetization, and preparing a magnet assembly;

[0130] The rest of the preparation method is the same as that in Example 2.

[0131] Example 10

[0132] The same process steps as in Example 2 are used, except that:

[0133] S2: Place every three NdFeB magnet units in a fixed fixture without magnetizing;

[0134] Add step S4' after step S4:

[0135] S4': magnetizing the magnet assembly welded in step S4 according to the Halbach method to obtain a Halbach magnet assembly.

[0136] Embodiment 11

[0137] The same process steps as those in Example 1 are used, except that: between steps S1 and S2, step S11 is further included: surface treatment of the magnet unit is performed to obtain a metal coating. The specific coating composition and thickness are shown in Table 1.

[0138] Comparative Example 1

[0139] A method for preparing a magnet assembly, compared with Example 2, the only difference is that: S4: the strong magnetic surface of the coastal Balbec magnet assembly (such as Figure 2 The joints S13 and S23 shown in the figure are laser welded.

[0140] Comparative Example 2

[0141] A method for preparing a magnet assembly, compared with Example 3, the only difference is that the pulse width in step S4 is 180ns.

[0142] Comparative Example 3

[0143] A method for preparing a magnet assembly, compared with Example 4, the only difference is that the frequency in step S4 is 350KHz.

[0144] Comparative Example 4

[0145] A method for preparing a magnet assembly, compared with Example 5, the only difference is that the peak power in step S4 is 45%.

[0146] Table 1 Coating and laser welding parameters of Examples 1-11 and Comparative Examples 1-4

[0147]

[0148] Table 2 Welding point parameters of Examples 1-13 and Comparative Examples 1-4

[0149]

[0150] The magnetic flux and shear force of the magnet assemblies of Examples 1-12 and Comparative Examples 1-4 were measured in the following manner:

[0151] 1) Magnetic flux: The magnetic flux of a magnet is measured by a fluxmeter.

[0152] 2) The magnetic flux attenuation rate represents the average magnetic flux attenuation rate of the magnet assembly before and after laser welding, that is, the magnetic flux attenuation rate = (M1-M2) / M1*100%, wherein: M1 represents the magnetic flux of the magnet assembly before welding (that is, M1 is the magnetic flux after the magnet unit is magnetized in step S2 or the magnetic flux after the magnet assembly is magnetized in step S4'), and M2 represents the magnetic flux after the magnet assembly is welded.

[0153] 3) Shear force: tested according to GB / T 7124-2008.

[0154] The specific test results are shown in Table 3.

[0155] Table 3 Performance of Examples 1-11 and Comparative Examples 1-4

[0156]

[0157]

[0158] The above results show that when the present invention performs laser welding through the adhesive layer formed by the glue or the like between the gaps of the end faces of two adjacent magnet units of the magnet assembly, by increasing the welding frequency, a Halbach magnet assembly with a magnetic flux attenuation rate of 3.00% can also be obtained. And with the increase of the laser frequency, the overlap of the welding points is high. Under the same pulse width and peak power, the welding points with high overlap have a shorter length, which is easy to cause cracks in the weld, and is not conducive to the improvement of the shear force of the magnet assembly. In addition, with the increase of the pulse width during laser welding, the equivalent circular area of ​​the welding point becomes larger, which will increase the magnetic flux attenuation rate of the magnet assembly after welding, and when the welding point is too large, it is easy to cause the marginal effect (such as uneven heat distribution, too high or too low temperature at the edge of the weld, etc.), thereby causing cracks, pores or other defects in the weld, thereby affecting the strength of the magnet assembly after welding. Furthermore, as the peak power during laser welding increases, the penetration ability during welding becomes stronger and the welding temperature also increases, so the depth of the welding point is too large, and too deep welding is likely to affect the magnetic field strength of the strong magnetic surface of the magnet unit, which will increase the flux loss of the magnet assembly. Furthermore, the present invention is easier to weld by providing a coating on the joint surface of two adjacent magnet units of the magnet assembly, and the flux attenuation rate and shear force after welding are also improved. The welding point and the strong magnetic surface are the application surfaces of the Halbach magnet assembly. Therefore, when the welding point is located on the strong magnetic surface of the magnet unit, although the strength of the magnet assembly can be increased, the flux attenuation rate of the magnet assembly is also significantly improved. Therefore, during the frequent use of the magnet assembly, the stability and reliability of its relative magnetic field will also decrease. The present invention optimizes the number of welding points between the gaps on the end faces of two adjacent magnet units of the magnet assembly, the equivalent circle diameter R of the welding point, and the length L of the welding point. q , the total length of the welding point L Q , the minimum distance S between the outer edge of the welding point and the surface of the magnet unit q , the depth D of the welding point toward the contact surface between the two adjacent magnet units q The coating type of the and / or welding point is changed, and the connection strength of the magnet structure and the stability in harsh environments such as high temperature and high humidity are significantly improved without changing the Halbach array mode of the magnet arrangement, thereby avoiding unnecessary loss of magnet performance. In addition, the preparation method of the magnet assembly of the present invention also significantly improves the assembly efficiency of the magnet assembly and can be widely used in large-scale production.

[0159] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A magnet assembly, characterized in that: The magnet assembly comprises at least two magnet units, wherein: Two adjacent magnet units have different magnetization directions; There is a welding point between two adjacent magnet units; and The weld has at least one feature selected from the following: (1) The welding point is located between the gaps of the end faces of the two adjacent magnet units, preferably the welding point is located between the gaps of the weak magnetic surfaces of the two adjacent magnet units; (2) The magnetic flux attenuation rate of the magnet assembly before and after welding is ≤5%.

2. The magnet assembly according to claim 1, characterized in that The number q of welding points between two adjacent magnet units is any integer between 1 and 6; Preferably, the total number Q of welding points of the magnet assembly satisfies the following relationship: (n-1)≤Q≤4*(n-1), where n is the number of magnet units; preferably, 2*(n-1)≤Q≤3*(n-1); Preferably, the equivalent circle diameter R of at least one or all of the welding points is less than 1 mm; preferably, the equivalent circle diameter R of all the welding points is less than 0.8 mm; for example, the equivalent circle diameter R of all the welding points is 0.1 mm to 1 mm, preferably 0.1 mm to 0.3 mm; Preferably, the length L of any welding point between two adjacent magnet units is q Satisfies the following relationship: 5%*L≤L q ≤40%*L, wherein L is the average value of the sum of the lengths of the two adjacent magnet units in the direction parallel to the contact surface between the two adjacent magnet units, preferably, 6%*L≤L q ≤20%*L; Preferably, the total length L of the welding points between two adjacent magnet units is Q Satisfies the following relationship: 10%*L≤L Q ≤80%*L, where L is the average value of the sum of the lengths of the two adjacent magnet units in the direction parallel to the contact surface between the two adjacent magnet units; preferably, 12%*L≤L Q ≤40%*L; Preferably, the minimum distance S between the outer peripheral edge of the welding point and the surface of the magnet unit is q ≥1mm; preferably, 5%*L≤S q <50%*L; Preferably, the distance S between the outer peripheral edge of the welding point and the center of the contact surface between the two adjacent magnet units is c Satisfy the following relationship: 15%*L≤S c <50%*L; preferably, 25%*L≤S c <50%*L; Preferably, the depth D of the welding point toward the contact surface between the two adjacent magnet units is q Satisfies the following relationship: D q ≤H*50%, preferably, H*5%≤D q ≤H*30%; wherein: H is the minimum value of the lengths of the two magnet units in the direction parallel to the contact surface between the two adjacent magnet units. Preferably, in the magnet assembly, two adjacent magnet units have different magnetization directions, and the magnetization directions of two magnet units on both sides of any magnet unit are opposite. Preferably, the magnet units in the magnet assembly are arranged in the order of a Halbach array. Preferably, the shape of the welding point can be circular, elliptical, square, rectangular, quasi-circular, quasi-elliptical, quasi-square, quasi-rectangular, etc.

3. The magnet assembly according to claim 1 or 2, characterized in that: The magnet assembly comprises at least two magnet units, wherein: Two adjacent magnet units have different magnetization directions; There is a welding point between two adjacent magnet units; and The welding point includes Nd, Fe, and B elements and other elements except Nd, Fe, and B elements. Preferably, the magnet unit may have a coating on the bonding surface with two adjacent magnet units, or may not have a coating, and the coating contains elements other than Nd, Fe and B elements. Preferably, the elements other than Nd, Fe and B are selected from one, two or more of Ni, Zn, Cu, P, Mo and the like. Preferably, the coating is a metal coating, for example, a Ni coating, a Zn coating, a Ni-Cu-Ni coating, a Cu-Ni coating or a Zn-Ni coating. Preferably, the thickness of the coating may be 1-30 μm, for example, 2-25 μm, preferably 5-20 μm, more preferably 8-15 μm. Preferably, the magnet units may or may not optionally include a bonding layer such as glue or adhesive except for the welding points. For example, the glue or adhesive used in the bonding layer is selected from one or more of epoxy resin, polyurethane, silicone, AB glue and anaerobic glue. Preferably, before two adjacent magnet units are connected via a welding point, the magnet units can be optionally magnetized magnet units or non-magnetized magnet units. Preferably, the magnetized magnet units can be combined by welding, or the welded magnet units can be magnetized.

4. The method for preparing a magnet assembly according to any one of claims 1 to 3, characterized in that: The preparation method comprises combining the two adjacent magnet units by welding at welding points.

5. The preparation method according to claim 4, characterized in that: The welding method may be laser welding, preferably pulse welding. Preferably, the pulse width of the laser welding is 50-150 ms; the frequency is 50-350 Hz; and the peak power is 10-40%. Preferably, in the method for preparing the magnet assembly, before two adjacent magnet units are welded together via welding points, the magnet units can be optionally magnetized magnet units or unmagnetized magnet units. Preferably, the magnetized magnet units can be combined by welding, or the welded magnet units can be magnetized.

6. The preparation method according to claim 4, characterized in that: The steps include: S1: Preparation of magnet unit; S2: magnetizing the magnet unit and arranging the magnets according to assembly requirements to form a magnet assembly; optionally, placing the magnet assembly in a fixing fixture; S3: Dispense glue on the magnet assembly, and then press and solidify it; S4: Laser welding is performed along the end face joints of adjacent magnets or the joints of the weak magnetic surfaces of magnets. Alternatively, the method for preparing the magnet assembly comprises the following steps: S1: Preparation of magnet unit; S2: Arranging magnets in the magnet unit according to assembly requirements to form a magnet assembly; optionally, placing the magnet assembly in a fixing fixture; S3: Dispense glue on the magnet assembly, and then press and solidify it; S4: magnetizing the magnet assembly according to the polarity direction requirements; S5: Laser welding is performed along the end face joints of adjacent magnets or the joints of the weak magnetic surfaces of magnets.

7. The method for preparing a magnet assembly according to any one of claims 4 to 6, characterized in that: Steps S4 and S5 may also be exchanged in order. Preferably, the method for preparing the magnet assembly further comprises performing surface treatment on the magnet unit obtained in step S1 to obtain a coating. Preferably, the method for preparing the magnet assembly may further include, during welding, using a cover plate tooling having holes or tracks that are exactly the same as the welding points, so that the welding equipment is accurately positioned at the welding position for welding. Preferably, the method for preparing the magnet assembly may further include using a visual detector to accurately locate the joints of the magnet units to achieve laser welding.

8. A motor, characterized in that: The motor comprises the magnet assembly according to any one of claims 1-3. Preferably, the motor comprises a stator assembly and a moving assembly. Preferably, the motor further comprises a control system, which can be integrated with the control system of the magnetic attraction component to achieve precise synchronous control, thereby improving the performance of the motor. Preferably, the motor further comprises a driving device, and the driving device and the magnet assembly are respectively arranged in the stator assembly and the moving assembly.

9. A photographing or video recording device, characterized in that: The photographing or video recording device comprises the motor according to claim 8.

10. An electronic device, characterized in that: The electronic device comprises the motor according to claim 8.

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