Laser welding process of neodymium iron boron Halbach magnetic assembly

Abstract

The invention discloses a laser welding process of a neodymium iron boron Halbach magnetic assembly. The laser welding process comprises the following steps: firstly, arranging a plurality of magnetized magnets in a Halbach array form; then glue is dispensed on the butt joint faces between the adjacent magnets, and the multiple magnets are glued to form a Halbach magnetic assembly; next, adjacent magnets are welded and fixed on the weak magnetic surface of the Halbach magnetic assembly in a nanosecond laser welding mode; glue is dispensed at the welding position, and the welding seam is filled and covered with glue while the Halbach magnetic assembly and the magnet fixing piece are fixed in a glue joint mode. According to the method, the Halbach magnetic assembly is assembled in the mode that glue joint is conducted firstly and then nanosecond laser welding is conducted, the welding operation is easy to conduct, the welding position is accurate, and magnetic performance attenuation can be controlled within a small range.

Description

Technical Field

[0001] The invention belongs to the technical field of magnet processing and preparation, and particularly relates to a laser welding process for a NdFeB Halbach magnetic component. Background Art

[0002] Halbach magnetic circuit has multiple advantages such as magnetic concentration and self-shielding. In particular, the characteristic of magnetic concentration can achieve several times more magnetic or suction force than ordinary magnets of the same volume. Halbach magnetic components prepared with Halbach magnetic circuit structure have been widely used in magnetic attraction, motors, magnetic transmission, scientific research and other fields. At present, most of the Halbach magnetic components use adhesive to bond multiple magnets together in the arrangement of the Halbach array. This assembly method has poor structural stability and weather resistance of the glue when the magnet bonding area is small and there is no support, which cannot meet the increasingly high-end use requirements. Although high weather-resistant glue can be used to improve the weather resistance of the glue to a certain extent, it will give up a certain degree of bonding convenience and glue bonding strength.

[0003] Patent CN118248429A discloses a magnetic suction component and its assembly method, a linear motor, a camera, and an electronic device. The patent discloses that the Halbach magnetic component is assembled by welding to improve the structural stability of the Halbach magnetic component. However, the process of welding the Halbach magnetic component disclosed in the patent has the following defects: 1. Before welding, the patent requires that the magnets be placed in the carrier, and then the multiple magnets are pushed sideways and pressed together by a push rod, so that the welding surfaces of two adjacent magnets are connected before welding can be performed. Affected by the manufacturing accuracy, wear condition, and deviation of the motion trajectory of the push rod itself, it is easy to cause uneven pressing force on the magnets, which in turn leads to inconsistent gaps between the magnets, thereby affecting the welding quality and the distribution of the magnetic field; 2. If the positioning accuracy of the push rod is insufficient when pushing the magnet sideways, the relative position of the magnet will be inaccurate, thus affecting the distribution of the magnetic field and the performance of the component. 3. The welding joint of the patent penetrates the magnet along the depth direction of the joint, and the coverage area of ​​the welding joint is too large, that is, the volume of the weld formed by welding is large, which causes great damage to the crystal structure of the magnet, resulting in greater loss of magnetic properties.

[0004] 4. The carrier used for assembling the magnet in this patent includes multiple structures such as a carrier body, a movable carrier, a cover plate, etc. Avoidance holes need to be opened on the cover plate to make way for welding, and magnetic adsorption parts need to be set on the opposite sides of the carrier body of the movable carrier. Therefore, this patent uses more assembly tooling parts, has a complex structure, and is costly. Summary of the invention

[0005] The purpose of the present invention is to provide a laser welding process for NdFeB Halbach magnetic components, which adopts the method of first gluing and then nanosecond laser welding to assemble the Halbach magnetic components. The welding operation is easy to perform and the welding position is accurate, and the magnetic performance attenuation can be controlled within a smaller range.

[0006] To achieve the above object, the present invention provides a laser welding process for a NdFeB Halbach magnetic assembly, comprising the following steps: S1, arranging the magnetized magnets in the form of a Halbach array; S2, applying glue on the butt joint surfaces between adjacent magnets to glue multiple magnets together to form a Halbach magnetic assembly; S3. Use nanosecond laser welding to weld and fix adjacent magnets on the weak magnetic surface of the Halbach magnetic assembly. The volume of all welds after welding shall not exceed 1.5% of the volume of the entire Halbach magnetic assembly. S4. Apply glue to the welding spot, and glue the Halbach magnetic assembly to the magnet fixing part to fill and cover the weld with glue.

[0007] Furthermore, in step S3, welding is performed at positions of the weak magnetic surface of the Halbach magnetic assembly close to both sides of the magnet, so that two welds are formed between two adjacent magnets.

[0008] Further, in step S3, the length of the magnet is 10 mm, the width is 2 mm, and the height is 1 mm. The width of each weld is 0.2 mm and the depth is 0.3 mm.

[0009] Furthermore, after step S4, the magnetic performance attenuation of the manufactured Halbach magnetic component is controlled below 3%, and the service life under high temperature and high humidity conditions of 85°C and 85% humidity reaches more than 500 hours.

[0010] Furthermore, in step S2, an upper magnetic jig, a lower magnetic jig and two push rods are used to assemble the magnets, and the multiple magnets after dispensing are arranged on the lower magnetic jig in the form of a Halbach array. The upper magnetic jig is then used to press the magnets from above, and then the two push rods are used to synchronously squeeze the magnets on both sides, so that all the magnets are combined and glued into a Halbach magnetic assembly.

[0011] Furthermore, in steps S2 and S4, the glue dispensed is low-temperature epoxy glue.

[0012] Furthermore, in step S3, nanosecond laser is used for welding, the welding temperature is 3000°C, and the welded magnet melts and cools within 1 second to form a weld.

[0013] Furthermore, in step S3, during welding, an inert gas is introduced for protection to prevent excessive oxidation of the magnet.

[0014] Furthermore, in step S3, nitrogen or argon is introduced for protection during welding.

[0015] After adopting the above scheme, the beneficial effects of the present invention are: 1. The present invention first glues a plurality of magnets together to form a Halbach magnetic assembly, and then welds the weak magnetic surface of the Halbach magnetic assembly. After the magnets are glued together, welding can be performed directly without using a carrier and a push rod to press the magnets. The welding is convenient and easy, and the gaps between the magnets are consistent, and the relative positions of the magnets are accurate, which will not affect the welding quality and the magnetic field distribution, and there is no need to use a carrier with a complex structure, thereby reducing the cost.

[0016] 2. Nanosecond laser welding is used to weld on the weak magnetic surface of the Halbach magnetic assembly. Welding on the weak magnetic surface will not cause magnetic loss to the strong magnetic surface, and will not affect the performance of the Halbach magnetic assembly. In addition, the nanosecond laser welding process has a small spot and high energy density, which will not cause through-cracks in the magnet and can form welds in a very small area. The volume of all welds after welding does not exceed 1.5% of the volume of the entire Halbach magnetic assembly, and the magnetic performance attenuation of the Halbach magnetic assembly can be controlled below 3%.

[0017] 3. When the Halbach magnetic assembly is used, it needs to be assembled into the corresponding magnet fixing part, so that glue can be applied at the welding point to glue the Halbach magnetic assembly to the magnet fixing part. The glue will fill and cover the weld, and the welding will not damage the coating on the surface of the magnet and affect the weather resistance of the Halbach magnetic assembly. The service life of the manufactured Halbach magnetic assembly under high temperature and high humidity conditions of 85°C and 85% humidity is more than 500 hours, and it has good high temperature and high humidity resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A distribution diagram of magnetic flux lines of a Halbach array; Figure 2 It is a schematic diagram of arranging a plurality of magnets after dispensing glue on a lower magnetic conductive fixture in the form of a Halbach array according to the present invention; Figure 3 This is a schematic diagram of the present invention using an upper magnetic fixture to press down a magnet; Figure 4 This is a schematic diagram of the present invention using two push rods to synchronously squeeze the magnets on both sides; Figure 5 A bottom view of the Halbach magnetic assembly of the present invention; Figure 6 This is a diagram showing the change in magnetic field intensity of the working surface before and after welding of the present invention; Figure 7 This is a schematic diagram of metallographic section of the nanosecond laser welding weld of the present invention; Figure 8It is a process flow chart of the present invention.

[0019] Description of labels: 1. Strong magnetic surface; 2. Weak magnetic surface; 21. Welding seam; 3. Upper magnetic fixture; 4. Lower magnetic fixture; 5. Push rod. DETAILED DESCRIPTION

[0020] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The Halbach array is a magnet structure that is a near-ideal structure in engineering. Its principle is to use magnets arranged in a certain pattern to enhance the magnetic field strength in a unit direction, so as to achieve the purpose of using the least amount of magnets to produce the strongest magnetic field. Figure 1 As shown, Figure 1 The figure is a magnetic flux distribution diagram of a Halbach array. The Halbach array includes three magnets arranged in sequence. The three solid arrows in the figure represent the polar directions of the three magnets respectively. The magnetic fields formed by the three magnets affect each other, so that the magnetic field strength on the upper side is effectively increased, and the magnetic field strength on the lower side is effectively reduced. Among them, the side with a stronger magnetic field strength of the Halbach magnetic component is called a strong magnetic surface, which is the working surface of the magnet, and the side with a weaker magnetic field strength is called a weak magnetic surface, which is the non-working surface. For example Figure 1 The top surface of the Halbach magnetic assembly is a strong magnetic surface, and the bottom surface is a weak magnetic surface.

[0022] Of course, the number of magnets in the Halbach magnetic assembly is not limited to three, but can also be five or more, all of which are arranged in the form of a Halbach display, and the number of magnets can be set as needed.

[0023] like Figure 2-8 As shown, the present invention provides a laser welding process for a NdFeB Halbach magnetic assembly, comprising the following steps: S1. Arrange the magnetized magnets in the form of a Halbach array. The magnets may be neodymium iron boron magnets. The number of magnets is three, for example. The arrangement is as follows: Figure 1 As shown, the magnetization directions of the magnets are vertically downward, horizontally to the right, and vertically upward. Figure 2 As shown vertically upward, horizontally to the right and vertically downward, if Figure 2 In the arrangement shown, the weak magnetic surface 2 is on the top of the magnet and the strong magnetic surface 1 is on the bottom of the magnetic field.

[0024] S2. After arranging multiple magnets in the form of a Halbach array, the butt joint surfaces between adjacent magnets can be determined, glue is dispensed on the butt joint surfaces between adjacent magnets, and then the multiple magnets are glued together to form a Halbach magnetic assembly.

[0025] Specifically, the magnet can be assembled using an upper magnetic fixture 3, a lower magnetic fixture 4 and two push rods 5, such as Figure 2 As shown, the glued magnets are first arranged on the lower magnetic fixture 4 in the form of a Halbach array. If there are three magnets, glue can be applied to the inner side surfaces of the left and right magnets, and the middle magnet does not need to be glued. Figure 3 As shown, the upper magnetic fixture 3 is then used to press the magnet above the magnet to prevent the magnet from shifting up and down; Figure 4 As shown, the two push rods 5 are then used to synchronously squeeze the magnets on both sides, so that all the magnets can be pressed together laterally, so that all the magnets are combined and glued into a Halbach magnetic assembly; using two push rods 5 to synchronously squeeze the magnets on both sides can ensure the uniformity and stability of the magnet combination, thereby improving the production quality and consistency of the Halbach magnetic assembly.

[0026] Preferably, the glue used for dispensing can be low-temperature epoxy glue, which has the advantages of low curing temperature, fast curing speed and good bonding strength.

[0027] S3. After gluing, the magnets have been assembled into a Halbach magnetic assembly. There is no need to use a push rod 5 or other tools to squeeze the magnets. The adjacent magnets can be directly welded and fixed on the weak magnetic surface 2 of the Halbach magnetic assembly by nanosecond laser welding. Specifically, a nanosecond laser is used to weld between adjacent magnets. During the welding process, a high temperature of nearly 3000°C can be generated. The melting and cooling of the welded magnets are completed in an instant (within 1 second) to form a weld 21. The welding speed is fast and the work efficiency is high. Figure 6 It can be seen that welding on the weak magnetic surface 2 will not cause magnetic loss to the strong magnetic surface 1 (working surface), and thus will not affect the performance of the application of Halbach magnetic components.

[0028] In addition, the nanosecond laser welding process has a small spot and high energy density, and can form a weld in a very small area. Taking a magnet with a length of 10 mm, a width of 2 mm, and a height of 1 mm as an example, the nanosecond laser welding process can form a weld 21 with a width of only 0.2 mm and a depth of only 0.3 mm, which can reduce the magnetic performance attenuation of the Halbach magnetic component.

[0029] Preferably, the volume of all welds 21 after welding can be controlled not to exceed 1.5% of the volume of the entire Halbach magnetic assembly, so that the attenuation of the magnetic properties of the Halbach magnetic assembly can be controlled below 3%.

[0030] like Figure 5 As shown, it is preferred to perform welding at the weak magnetic surface 2 of the Halbach magnetic assembly close to both sides of the magnet, so that there are two welds 21 between two adjacent magnets. Such welding can reduce the attenuation of the magnetic properties of the main magnetic field in the middle position and ensure the firmness of the welding between the magnets.

[0031] In addition to the nanosecond laser welding process, the pulse laser welding process can also be used to weld the weak magnetic surface 2 of the Halbach magnetic component. However, when the pulse laser is welded, the spot is large and the welding area is large, and it is inevitable that through cracks will be generated at the weld 21 after welding, which will affect the structural performance. Figure 7 As shown, the nanosecond laser welding process will not produce through cracks and the welding area is small, so the nanosecond laser welding process is preferably used.

[0032] Furthermore, during welding, an inert gas needs to be introduced for protection to prevent excessive oxidation, and the inert gas can be nitrogen or argon.

[0033] S4. When used, the Halbach magnetic assembly needs to be assembled into the corresponding magnet fixing part (not shown in the figure), which can be a plastic shell or other shell parts; specifically, the weak magnetic surface of the Halbach magnetic resistance part is assembled into the magnet fixing part, and the strong magnetic surface of the Halbach magnetic resistance part is exposed. Therefore, after welding, glue can be dispensed at the welding point to glue and fix the Halbach magnetic assembly to the magnet fixing part. The glue dispensed can also be low-temperature epoxy glue; at the same time, the glue will fill and cover the weld, and the weather resistance of the Halbach magnetic assembly will not be affected by welding to damage the coating on the surface of the magnet. The service life of the manufactured Halbach magnetic assembly under high temperature and high humidity conditions of 85°C and 85% humidity reaches more than 500 hours, and the high temperature and high humidity resistance is good.

[0034] The following is further described by specific examples: Embodiment 1: The Halbach magnetic components were assembled using the process of gluing followed by nanosecond laser welding as described above.

[0035] Embodiment 2: The Halbach magnetic assembly is assembled by gluing first and then pulse laser welding. The specific steps are the same as those in Example 1, except that the pulse laser welding process is used to weld on the weak magnetic surface of the Halbach magnetic assembly.

[0036] Embodiment 3: The magnets are assembled into a Halbach magnetic assembly using only a gluing process. The assembly method can refer to steps S1-3 described in the present invention, or refer to the method disclosed in patent CN118248429A.

[0037] Embodiment 4: Only the argon arc welding process is used to weld the magnets to assemble into a Halbach magnetic assembly. For details, please refer to the assembly steps disclosed in patent CN118248429A.

[0038] Embodiment 5: Only the resistance welding process is used to weld the magnets to assemble into a Halbach magnetic assembly. For details, please refer to the assembly steps disclosed in patent CN118248429A.

[0039] The Halbach magnetic assembly assembled in the above embodiment was subjected to performance testing, and the test results are shown in the following table:

[0040] From the table above, we can see that pulse laser welding, argon arc welding and resistance welding processes will all produce through cracks in magnets, and argon arc welding will even directly destroy the magnets, while resistance welding will instantly greatly reduce the magnetic properties or even completely eliminate the magnetism. Both will have a great impact on the performance of the magnets, so they are not applicable. The pulse laser welding process can only control the magnetic performance attenuation of Halbach magnetic components between 5% and 10%, which is not as good as the nanosecond laser welding process.

[0041] In addition, although neither gluing nor nanosecond laser welding processes will cause through-cracks in the magnets, the high temperature and high humidity (85°C and 85% humidity) life of the Halbach magnetic assembly assembled only by gluing is only 48 hours, which is too short and has low high temperature and high humidity resistance, so the nanosecond laser welding process is most appropriate. In order to facilitate welding without affecting the performance of the magnets or damaging the magnets, the process of gluing multiple magnets first and then performing nanosecond laser welding can be used.

[0042] The above description is only a preferred embodiment of the present invention and is not a limitation on the design of this case. Any equivalent changes made based on the design key of this case shall fall within the protection scope of this case.

Claims

1. A laser welding process for NdFeB Halbach magnetic components, characterized in that: The following steps are involved: S1, arranging the magnetized magnets in the form of a Halbach array; S2, applying glue on the butt joint surfaces between adjacent magnets to glue multiple magnets together to form a Halbach magnetic assembly; S3. Use nanosecond laser welding to weld and fix adjacent magnets on the weak magnetic surface of the Halbach magnetic assembly. The volume of all welds after welding shall not exceed 1.5% of the volume of the entire Halbach magnetic assembly. S4. Apply glue to the welding spot, and glue the Halbach magnetic assembly to the magnet fixing part to fill and cover the weld with glue.

2. The laser welding process of a NdFeB Halbach magnetic assembly as claimed in claim 1, characterized in that: In step S3, welding is performed at the weak magnetic surface of the Halbach magnetic assembly close to both sides of the magnet, and two welds are formed between two adjacent magnets.

3. The laser welding process of a NdFeB Halbach magnetic assembly as claimed in claim 2, characterized in that: In step S3, the magnet has a length of 10 mm, a width of 2 mm, and a height of 1 mm, and each weld has a width of 0.2 mm and a depth of 0.3 mm.

4. The laser welding process of a NdFeB Halbach magnetic assembly as claimed in claim 1, characterized in that: After step S4, the magnetic performance attenuation of the manufactured Halbach magnetic component is controlled below 3%, and the service life under high temperature and high humidity conditions of 85°C and 85% humidity reaches more than 500 hours.

5. The laser welding process of a NdFeB Halbach magnetic assembly as claimed in claim 1, characterized in that: In step S2, an upper magnetic fixture, a lower magnetic fixture and two push rods are used to assemble magnets. The multiple magnets after dispensing are arranged on the lower magnetic fixture in the form of a Halbach array. The upper magnetic fixture is then used to press the magnets on top of the magnets. The two push rods are then used to squeeze the magnets on both sides simultaneously, so that all the magnets are combined and glued into a Halbach magnetic assembly.

6. The laser welding process of a NdFeB Halbach magnetic assembly as claimed in claim 1, characterized in that: In steps S2 and S4, the glue dispensed is low-temperature epoxy glue.

7. The laser welding process of a NdFeB Halbach magnetic assembly as claimed in claim 1, characterized in that: In step S3, nanosecond laser is used for welding, and the welding temperature is 3000°C. The welded magnet melts and cools within 1 second to form a weld.

8. The laser welding process of a NdFeB Halbach magnetic assembly as claimed in claim 1, characterized in that: In step S3, during welding, an inert gas is introduced for protection to prevent excessive oxidation of the magnet.

9. The laser welding process of a NdFeB Halbach magnetic assembly as claimed in claim 8, characterized in that: In step S3, nitrogen or argon is introduced for protection during welding.

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