Preparation Method of a Square Nanocrystalline Core Common-Mode Inductor

Abstract

This application relates to the technical field of the preparation of nanocrystalline magnetic cores, and particularly to a preparation method of a square nanocrystalline magnetic core common mode inductor, which includes the following construction steps: incoming material inspection, stacking and shaping, end face flattening, heat treatment, dipping treatment, curing and shaping, surface treatment. It can achieve batch processing of magnetic core raw materials, enabling them to be transformed from an easily producible annular structure into a rectangular structure. Moreover, the transformed structure has stable mechanical properties, is not prone to springback, has good finished product quality, the magnetic flux path of the magnetic core with a rectangular structure also becomes uniform, which can ensure the convenience of processing amorphous and nanocrystalline magnetic cores, at the same time make the magnetic flux path of the magnetic core uniform, reduce the winding difficulty, enhance the performance of the magnetic core, and meet the production requirements.

Description

Technical Field

[0001] The present application relates to the technical field of nanocrystalline magnetic core preparation, and in particular to a method for preparing a square nanocrystalline magnetic core common mode inductor. Background Art

[0002] Nanocrystalline magnetic core is a soft magnetic structure with nanoscale crystal structure. The alloy is directly formed into amorphous thin strip from molten state through rapid cooling technology, and then the amorphous state is transformed into nanocrystalline state through heat treatment. Nanocrystalline magnetic core is mainly used in power electronics fields such as common mode inductors, high frequency transformers, current transformers, drive transformers, etc.

[0003] At present, in the processing of nanocrystalline magnetic cores, an amorphous nanocrystalline magnetic core is taken and heat treated at a temperature of about 400°C. Then nitrogen is introduced into the furnace for 8-10 hours to transform the amorphous state into the nanocrystalline state to obtain a nanocrystalline magnetic core.

[0004] However, in actual applications, in order to facilitate shearing processing, amorphous nanocrystalline magnetic cores are often designed into a ring shape. However, the magnetic flux path of the ring-shaped magnetic core is poor, and it is difficult to wind the wire evenly during the subsequent coil winding, which leads to reduced efficiency and increased losses of the magnetic core. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art of the above-mentioned background technology, the present application provides a method for preparing a square nanocrystalline magnetic core common-mode inductor, which can ensure the convenient processing of amorphous nanocrystalline magnetic cores, while making the magnetic flux path of the magnetic core uniform, reducing the difficulty of winding, and enhancing the performance of the magnetic core.

[0006] The present application provides a method for preparing a square nanocrystalline magnetic core common mode inductor, which adopts the following technical solution:

[0007] A method for preparing a square nanocrystalline magnetic core common mode inductor comprises the following steps:

[0008] S1: Incoming material inspection: The surface of each core material is free of burrs and kept dry, and the single-side thickness of the core material is controlled within the specified range;

[0009] S2: stacking and shaping: inserting the core into the first pressing sheet, stacking a plurality of the magnetic core materials on the first pressing sheet in sequence, placing the core in the middle of the magnetic core materials, and then taking the second pressing sheet and setting it at an end away from the first pressing sheet, the second pressing sheet is plugged into the core to obtain a stacked combined structure;

[0010] S3: End face flattening: Place multiple of the laminated combined structures in a fixture in sequence. Space between adjacent two of the laminated combined structures with splints. Simultaneously flatten the end faces of multiple of the laminated combined structures through a material pressing component;

[0011] S4: Heat treatment: Place the laminated combined structure in a heat treatment furnace for heat treatment;

[0012] S5: Impregnation treatment: Place the heat-treated laminated combined structure in a vacuum pressure impregnation device for impregnation treatment; S6: Curing and shaping: Bake and cure the impregnated laminated combined structure, then disassemble the laminated combined structure from the fixture. Then disassemble the cured and shaped magnetic core raw material, the first pressing sheet, the second pressing sheet, and the core. The cured and shaped magnetic core raw material is formed into a nanocrystalline magnetic core;

[0013] S7: Surface treatment: Remove the redundant insulating paint on the surface of the nanocrystalline magnetic core, and perform surface loss reduction treatment and surface protection treatment on the nanocrystalline magnetic core to obtain the finished magnetic core.

[0014] By adopting the above technical solution, through strict screening of the magnetic core raw material to ensure the quality of the raw material, without burrs, dry, and with a thickness within the specified range, it helps to ensure the performance and stability of the final product. Adopting the method of lamination and shaping enables multiple magnetic core raw materials to be stacked tightly and neatly together. At the same time, through the end face flattening treatment, the flatness and consistency of the magnetic core raw material are ensured. Affected by the material of the magnetic core raw material, the magnetic core raw material deforms after being pressurized, turning the circular magnetic core into a rectangular magnetic core. Through heat treatment, the internal organizational structure of the magnetic core can be improved, and its mechanical properties and magnetic properties can be enhanced. The impregnation treatment can enhance the insulation performance and corrosion resistance of the magnetic core, and the baking and curing make the impregnated layer adhere more firmly to the surface of the magnetic core to improve the durability and reliability of the magnetic core, thereby realizing the transformation from an amorphous nanocrystalline magnetic core to a nanocrystalline magnetic core, while maintaining the shaping without recovering deformation. Finally, by removing the redundant insulating paint, performing surface loss reduction treatment and surface protection treatment, the surface quality of the magnetic core is further optimized, which helps to reduce the loss caused by friction and corrosion during use.

[0015] Compared with the prior art, through the processing steps of incoming material inspection, lamination and shaping, end face flattening, heat treatment, impregnation treatment, curing and shaping, and surface treatment, batch processing of magnetic core raw materials can be realized, enabling it to be transformed from an easily produced annular structure into a rectangular structure. Moreover, the mechanical properties of the transformed structure are stable, and it is not easy to have a springback situation. The finished product has good quality, and the magnetic flux path of the rectangular magnetic core also becomes uniform. After being processed through the above steps, it can ensure the convenience of processing the amorphous nanocrystalline magnetic core, while making the magnetic flux path of the magnetic core uniform, reducing the winding difficulty, enhancing the use performance of the magnetic core, and meeting the production requirements.

[0016] Preferably, in the processing step of S2, the shapes and structures of the first pressing piece and the second pressing piece are the same, and they are twice the weight of the magnetic core material.

[0017] By adopting the above technical solution, in the stacking and shaping step of preparing the rectangular nanocrystalline magnetic core common mode inductor, the shapes and structures of the first pressing piece and the second pressing piece are the same, which can ensure that uniform pressure is applied to the magnetic core material during the stacking process, so as to obtain a more regular and compact stacked combination structure, which helps to improve the accuracy and consistency of the magnetic core, and provides guarantee for subsequent processing and the performance of the final product.

[0018] Secondly, the weights of the first pressing piece and the second pressing piece are designed to be twice that of the magnetic core material. This ratio helps to generate sufficient pressure during the stacking process, so that the magnetic core materials are more closely combined together, which can play a role in enhancing the structural strength of the magnetic core, reducing internal voids, and improving the electrical performance of the magnetic core.

[0019] Preferably, the core includes at least two core bodies, and the core bodies are detachably connected, and the overall shape of the core is a rectangular structure.

[0020] By adopting the above technical solution, during the preparation process, the rectangular core can provide stable support and positioning for the magnetic core material, so as to ensure that the shape and size of the magnetic core meet the requirements, which helps to ensure the accuracy and consistency of the magnetic core.

[0021] Secondly, the design of the detachably connected core bodies provides good flexibility and convenience, enabling the core to be quickly assembled and disassembled according to specific needs, which helps to simplify the preparation process, greatly improve the production efficiency, and at the same time is convenient for maintaining and replacing the core to reduce the use cost.

[0022] Preferably, the core includes a first core body, a second core body and a third core body. The first core body and the second core body are right trapezoidal structures with the same shape and size, and the third core body is an isosceles trapezoidal structure. The first core body, the second core body and the third core body are set at the same height. In the processing step of S2, one waist surface of the third core body abuts against the inclined surface of the first core body, and the other waist surface of the third core body abuts against the inclined surface of the second core body. After the three are assembled, a rectangular structure is formed. The outer edges of the first core body and the second core body are all rounded and are simultaneously abutted against the inner wall of the magnetic core material.

[0023] By adopting the above technical solution, the first core body and the second core body are designed as right trapezoidal structures with the same shape and size, while the third core body is an isosceles trapezoidal structure. This design enables the three core bodies to be closely assembled together to form a stable rectangular structure, so as to provide uniform supporting force for the magnetic core material and ensure the flatness and consistency of the magnetic core.

[0024] In addition, the outer edges of the first core and the second core are all rounded, which can reduce the stress concentration phenomenon generated during the processing, improve the fatigue resistance and service life of the magnetic core, help to improve the appearance quality of the magnetic core, and is beneficial to improving the electrical performance of the magnetic core.

[0025] Preferably, in the processing step of S4, the following processes are included:

[0026] S4.1: First, evacuate the cavity of the heat treatment furnace, and then introduce an inert gas into the cavity;

[0027] S4.2: When the temperature rises to the starting temperature, place the entire fixture in the cavity;

[0028] S4.3: Set at least one preset temperature node, gradually increase the temperature in sequence and maintain it for a period of time until the last preset temperature node is reached; at the same time, increase the magnetic field in the cavity;

[0029] S4.4: Cool down to a cooling temperature node.

[0030] By adopting the above technical solution, by first evacuating the cavity of the heat treatment furnace and then introducing an inert gas, the chemical reaction between the magnetic core material and oxygen or other active gases in the air during the heat treatment process can be effectively reduced to ensure the purity and performance stability of the magnetic core; by setting multiple preset temperature nodes, gradually increasing the temperature in sequence, and increasing the magnetic field at a specific temperature, this treatment method can finely control the microstructure and magnetic properties of the magnetic core, realize the transformation from the amorphous nanocrystalline magnetic core to the nanocrystalline magnetic core, and moreover, the gradual increase in temperature during the heat treatment process helps to reduce the thermal stress of the magnetic core to prevent cracks or deformation of the magnetic core during the heat treatment process. Finally, cooling down to a cooling temperature node ensures that the magnetic core can be slowly cooled after the heat treatment to avoid internal stress caused by rapid cooling, further ensuring the quality and performance of the magnetic core.

[0031] Preferably, the inert gas includes nitrogen and argon. In the processing step of S4.1, when the temperature in the heat treatment furnace is below 500 °C, nitrogen is introduced; when the temperature in the heat treatment furnace is above 500 °C, argon is introduced.

[0032] By adopting the above technical solution, according to the temperature in the heat treatment furnace, nitrogen or argon can be flexibly selected to better protect the magnetic core material from oxidation or other chemical reactions. Moreover, the present application utilizes the characteristics of nitrogen and argon having different protection effects at different temperatures, making the protection effect more accurate and efficient, and can effectively reduce the surface contamination and oxide layer formation of the magnetic core, thereby improving the quality and electrical performance of the magnetic core.

[0033] Preferably, in the processing step of S4.3, when the temperature in the heat treatment furnace is 480 °C, it is maintained for 12 hours.

[0034] By adopting the above technical solution, maintaining at 480 °C for 12 hours can enable the atoms inside the magnetic core material to have sufficient time and energy for rearrangement and structural adjustment, optimize its microstructure, improve magnetic properties and mechanical properties, help eliminate internal stress and defects in the material, improve the uniformity and consistency of the magnetic core, so as to ensure that the magnetic core material reaches a stable crystal structure state, thereby improving its stability during use.

[0035] Preferably, in the processing step of S4.4, when the magnetically annealed magnetic core material is taken out of the heat treatment furnace, the temperature of the nanocrystalline magnetic core is maintained above 300 °C.

[0036] By adopting the above technical solution, taking out the magnetic core at a certain high temperature can utilize its residual heat for subsequent surface treatment or other steps that require heat assistance, thereby improving energy efficiency and processing efficiency. In addition, it can reduce the thermal stress generated by rapid temperature changes, and further reduce the risk of magnetic core cracking or deformation, ensuring the quality and performance of the magnetic core.

[0037] Preferably, in the processing step of S5, first immerse the laminated combined structure in the hardening liquid for 1 minute, and then filter and dry for 30 minutes until the hardening liquid penetrates into the microstructure of the magnetic core material; in the processing step of S6, place the impregnated laminated combined structure in a drying furnace for baking, and the temperature in the drying furnace is 140 °C and maintained for 10 hours.

[0038] By adopting the above technical solution, the hardening liquid can fill the tiny pores inside the material, improve the density and mechanical properties of the material. By immersing the laminated combined structure in the hardening liquid and preventing the hardening liquid from penetrating into the microstructure of the magnetic core material, the hardness and wear resistance of the magnetic core can be enhanced; drying at 140 °C for 10 hours can ensure that the hardening liquid is uniformly cured inside the magnetic core to form a stable structure.

[0039] Preferably, after the processing step of S7, spray treatment is carried out according to 20 - 30 μm on the surface of the nanocrystalline magnetic core.

[0040] By adopting the above technical solution, through spray treatment, a uniform and dense protective layer can be formed on the surface of the nanocrystalline magnetic core. The protective layer can effectively isolate oxygen, moisture and other corrosive substances in the external environment, thereby extending the service life of the magnetic core. Moreover, controlling the spray thickness within the range of 20 - 30 μm can not only ensure that the protective layer has sufficient thickness to provide good protection, but also avoid performance degradation or cost increase caused by an overly thick coating.

[0041] In summary, the present application includes at least one of the following beneficial technical effects:

[0042] 1. Compared with the prior art, after processing steps such as incoming material inspection, lamination and shaping, end face flattening, heat treatment, dipping treatment, curing and shaping, and surface treatment, it is possible to achieve batch processing of magnetic core raw materials, enabling them to be transformed from an easily producible annular structure into a rectangular structure. Moreover, the transformed structure has stable mechanical properties, is not prone to springback, has good finished product quality, and the magnetic flux path of the rectangular-structured magnetic core also becomes uniform. After being processed through the above steps, it can ensure the convenience of processing amorphous nanocrystalline magnetic cores, while making the magnetic flux path of the magnetic core uniform, reducing the winding difficulty, enhancing the performance of the magnetic core, and meeting the production requirements;

[0043] 2. The detachable core design provides good flexibility and convenience, enabling the core to be quickly assembled and disassembled according to specific needs, helping to simplify the preparation process, greatly improving production efficiency, and also facilitating the maintenance and replacement of the core to reduce the usage cost;

[0044] 3. According to the temperature in the heat treatment furnace, nitrogen or argon can be flexibly selected to better protect the magnetic core material from oxidation or other chemical reactions. Moreover, the present application utilizes the characteristics that nitrogen and argon have different protection effects at different temperatures, making the protection effect more precise and efficient, effectively reducing the surface contamination and formation of oxide layers of the magnetic core, thereby improving the quality and electrical performance of the magnetic core. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a schematic structural diagram of the magnetic core raw material in the embodiment of the present application.

[0046] Figure 2 is an exploded view of the laminated combined structure in the embodiment of the present application.

[0047] Figure 3 is a schematic structural diagram of a core in the embodiment of the present application.

[0048] Figure 4 is a schematic structural diagram of a pressure feeding component in the embodiment of the present application.

[0049] Figure 5 is a schematic structural diagram of another pressure feeding component in the embodiment of the present application.

[0050] Description of reference numerals: 1. Stacked combination structure; 11. Magnetic core raw material; 12. First pressing sheet; 13. Second pressing sheet; 14. Core; 141. First core body; 142. Second core body; 143. Third core body; 144. Lifting rod; 1441. Lifting part; 1442. Connecting part; 1443. Insertion part; 2. Fixture; 3. Pressing plate; 4. Pressing material assembly; 411. First pressing plate; 412. Threaded rod; 413. Locking nut; 421. Second pressing plate; 422. Position adjusting rod; 423. Buffer; 424. Driven bevel gear; 425. Mounting seat; 426. Driving shaft; 427. Driving bevel gear. Detailed implementation manners

[0051] The following further describes this application Figures 1-5 in detail with reference to the accompanying drawings.

[0052] An embodiment of this application discloses a preparation method for a square nanocrystalline magnetic core common mode inductor.

[0053] Referring to Figure 1 and Figure 2 , a preparation method for a square nanocrystalline magnetic core common mode inductor includes the following construction steps:

[0054] S1: Incoming material inspection: The surface of each magnetic core raw material 11 has no burrs, is kept dry, and the single-sided thickness of the magnetic core raw material 11 is controlled within a specified range value.

[0055] In this application, the thickness of the strip is inspected and controlled to be 16 - 18. The surface cannot have burrs, and the raw materials cannot be affected by moisture to avoid oxidation and rust of the strip. Then, the strip is slit. The width dimension of the slit strip is 8 mm. Similarly, the surface of the strip material has no burrs or other abnormalities. Then, the strip material is wound into a circular non-crystalline nanocrystalline magnetic core, and the single-sided thickness of the magnetic core is 5 mm, which is also called the magnetic core raw material 11 in this application. It has high toughness and elasticity itself. The circular structure does not need to consider the corner angle, and the winding speed is fast. In the processing step of S1, multiple strip materials are uniformly wound into circular non-crystalline nanocrystalline magnetic cores with the same structure first to effectively improve production efficiency.

[0056] S2: Stacking and shaping: Insert the core 14 into the first pressing sheet 12. Multiple magnetic core raw materials 11 are stacked on the first pressing sheet 12 in sequence, with the core 14 placed in the middle of the magnetic core raw materials 11. Then, take the second pressing sheet 13 and set it at one end far from the first pressing sheet 12. The second pressing sheet 13 is inserted into the core 14 to obtain the stacked combination structure 1.

[0057] Specifically, the first pressing piece 12 and the second pressing piece 13 have the same shape and structure, and are twice the weight of the magnetic core raw material 11. The core 14 includes at least two core bodies, which are detachably connected to each other, and the overall shape of the core 14 is a rectangular structure.

[0058] This application provides a preferred structure of the core 14. Referring to Figure 2 , the core 14 includes a first core body 141, a second core body 142, and a third core body 143. The first core body 141 and the second core body 142 are right trapezoidal structures with the same shape and size. The third core body 143 is an isosceles trapezoidal structure. The first core body 141, the second core body 142, and the third core body 143 are arranged at the same height, such that one waist surface of the third core body 143 abuts against the inclined surface of the first core body 141, and the other waist surface of the third core body 143 abuts against the inclined surface of the second core body 142. After the three are assembled, a rectangular structure is formed. The outer edges of the first core body 141 and the second core body 142 are all rounded.

[0059] During application, first insert the large ends of the first core body 141 and the second core body 142 into the first pressing piece 12. Then, hang a plurality of magnetic core raw materials 11 on the outsides of the first core body 141 and the second core body 142. Next, take the third core body 143 and insert its small end into the position between the large ends of the first core body 141 and the second core body 142 until one waist surface of the third core body 143 abuts against the inclined surface of the first core body 141, and the other waist surface of the third core body 143 abuts against the inclined surface of the second core body 142. After the three are assembled, a rectangular structure is formed, and the elastic annular magnetic core raw material 11 is extruded into a rectangular magnetic core raw material 11. At this time, the inner wall of the magnetic core raw material 11 is completely attached to the core 14. Finally, insert the second pressing piece 13 into the core 14. Under the combined action of the first pressing piece 12 and the second pressing piece 13, a plurality of magnetic core raw materials 11 can be extruded together, so that the end faces of two adjacent magnetic core raw materials 11 can be attached.

[0060] In this application, the first core body 141 and the second core body 142 are designed as right trapezoidal structures with the same shape and size, while the third core body 143 is an isosceles trapezoidal structure. This design enables the three core bodies to be closely assembled together to form a stable rectangular structure, thereby providing uniform support force for the magnetic core raw material 11 and ensuring the flatness and consistency of the magnetic core.

[0061] In addition, the outer edges of the first core body 141 and the second core body 142 are all rounded, which can reduce the stress concentration phenomenon generated during the processing, improve the fatigue resistance and service life of the magnetic core, contribute to improving the appearance quality of the magnetic core, and is beneficial to improving the electrical performance of the magnetic core.

[0062] This application provides another preferred structure of the core 14. Referring toFigure 3 , on the basis of the previous core 14, guiding grooves are respectively formed on the inclined surfaces of the first core body 141 and the second core body 142. Correspondingly, guide blocks (not shown in the figure) are respectively fixed on the two waist surfaces of the third core body 143. During the assembly process of the first core body 141, the second core body 142 and the third core body 143, the two guide blocks are respectively slidably fitted with the adjacent guiding grooves, so that the gaps between the first core body 141 and the third core body 143 and between the second core body 142 and the third core body 143 tend to zero.

[0063] Furthermore, an installation groove and a sliding groove are formed inside the third core body 143. The extending direction of the installation groove is consistent with the length direction of the third core body 143. There are two sliding grooves which are symmetrically arranged along the center line of the installation groove. The sliding grooves penetrate from the end of the installation groove towards the direction of the first core body 141 or the second core body 142. Correspondingly, extension grooves are respectively formed at the positions of the first core body 141 close to the sliding groove and the second core body 142 close to the sliding groove. The extension grooves and the sliding grooves are on the same extension line.

[0064] A lifting rod 144 is arranged in the installation groove. The lifting rod 144 includes a lifting part 1441, a connecting part 1442 and a plugging part 1443. Among them, the lifting part 1441 is assembled with the connecting part 1442 through a bearing. There are two plugging parts 1443 which are respectively fixed on both sides of the connecting part 1442. In this application, the plugging part 1443 includes two parts of nodes. The nodes are fixed to each other and to the connecting part 1442 through hinges. At the same time, the nodes of the plugging part 1443 far from the connecting part 1442 are respectively slidably connected with the adjacent sliding grooves. In addition, external threads are formed on the outer wall of the end of the lifting part 1441 far from the connecting part 1442. In this application, the end of the lifting part 1441 provided with external threads faces the large end of the third core body 143.

[0065] During application, after the first core body 141, the second core body 142 and the third core body 143 are assembled, the lifting part 1441 is rotated by a tightening tool to make the lifting part 1441 descend. The plugging part 1443 slides along the sliding groove until it transitions into the extension groove, further improving the connection density of the three and greatly enhancing the stable connection performance of the three.

[0066] In the stacking and shaping step S2 of this application, the core 14 with a rectangular structure can provide stable support and positioning for the magnetic core raw material 11, thereby ensuring that the shape and size of the magnetic core meet the requirements. The detachable connection design of the core body provides good flexibility and convenience, enabling the core 14 to be quickly assembled and disassembled according to specific requirements, helping to simplify the preparation process, improve production efficiency, facilitate the maintenance and replacement of the core 14, and reduce the use cost.

[0067] Meanwhile, the first pressing plate 12 and the second pressing plate 13 have the same shape and structure, which can ensure that during the stacking process, uniform pressure is applied to the magnetic core raw material 11, so as to obtain a more regular and compact stacked combination structure 1. Moreover, the weights of the first pressing plate 12 and the second pressing plate 13 are designed to be twice that of the magnetic core raw material 11. This ratio helps to generate sufficient pressure during the stacking process, making the magnetic core raw material 11 bind more tightly together, contributing to improving the accuracy and consistency of the magnetic core, and providing guarantee for subsequent processing and the performance of the final product.

[0068] In this application, the core 14, the first pressing plate 12, and the second pressing plate 13 are all made of iron materials. The magnetic core raw material 11 itself has good magnetism. Utilizing its own properties, there is a certain attracting ability between the structures, enhancing the overall structural stability of the stacked combination structure 1.

[0069] S3: Flattening the end face: Place multiple stacked combination structures 1 in the fixture 2 in sequence. The fixture 2 is in the shape of a rectangular frame. The side walls of the fixture 2 are all steel plates with through holes, and the through holes are evenly arranged. Adjacent two stacked combination structures 1 are spaced by a clamping plate. The end faces of multiple stacked combination structures 1 are flattened simultaneously through the pressing component 4.

[0070] This application provides a preferred structure of the pressing component 4. Refer to Figure 4 , which includes a first pressing plate 411, a threaded rod 412, and a locking nut 413. Among them, the outer wall of the threaded rod 412 is provided with an external thread. The threaded rod 412 passes through one of the through holes. The first pressing plate 411 is fixed at the end of the threaded rod 412 and arranged inside the fixture 2, such that the side walls of the first pressing plate 411 that are close to each other are parallel to each other and perpendicular to the extending direction of the threaded rod 412. Two locking nuts 413 are arranged on each threaded rod 412. When the first pressing plate 411 abuts against the side wall of the stacked combination structure 1, rotate the two locking nuts 413, thereby being able to limit the positions of the threaded rod 412 and the first pressing plate 411. In this application, a set of pressing components 4 is arranged on each side wall of the fixture 2, so that multiple stacked combination structures 1 placed inside the four first pressing plates 411 can be squeezed by the clamping plate until the outer end face of the magnetic core raw material 11 is flattened, and then a rectangular magnetic core raw material 11 with a more stable structure is formed.

[0071] This application provides another preferred structure of the pressing component 4. Refer to Figure 5 , a second pressing plate 421 and an adjusting rod 422. Among them, there are two second pressing plates 421 and two adjusting rods 422. The outer wall of one end of the adjusting rod 422 is provided with a right-handed thread, and the other end has a left-handed thread. Pass the two adjusting rods 422 through the two second pressing plates 421 respectively, and make the two second pressing plates 421 parallel to each other and the two adjusting rods 422 parallel to each other.

[0072] Specifically, two position adjusting rods 422 are respectively threadedly connected to the second pressing plates 421 close to them. The two second pressing plates 421 are simultaneously placed inside the fixture 2 and distributed at the opposite side walls of the fixture 2. Buffer members 423 are respectively provided between the two second pressing plates 421 and the side walls of the fixture 2 close to them. Both ends of the position adjusting rod 422 are respectively rotatably connected to the side walls of the fixture 2 close to it. One end of the position adjusting rod 422 extending outside the fixture 2 is provided with a driven bevel gear 424. More specifically, a mounting seat 425 is fixed outside the side wall of the fixture 2. A driving shaft 426 is rotatably connected to the mounting seat 425. Driving bevel gears 427 are respectively provided at both ends of the driving shaft 426, such that the driving bevel gears 427 mesh with the driven bevel gears 424 close to them.

[0073] During application, when the driving shaft 426 is rotated, the driving bevel gears 427 can rotate, thereby driving the two driven bevel gears 424 to rotate. The position adjusting rods 422 on the driven bevel gears 424 can also rotate, and then drive the two second pressing plates 421 to move closer to or away from each other. In this application, two sets of material pressing components 4 are provided inside the fixture 2, so that multiple sets of stacked combination structures 1 placed inside the four second pressing plates 421 can be pressed by the clamping plates until the outer end faces of the magnetic core materials 11 are flattened, and then rectangular magnetic core materials 11 with a more stable structure are formed.

[0074] S4: Heat treatment: Place the stacked combination structure 1 in a heat treatment furnace for heat treatment.

[0075] In the processing steps of S4, the following operations are included:

[0076] S4.1: First, evacuate the cavity of the heat treatment furnace, and then introduce an inert gas into the cavity. Among them, the inert gas includes nitrogen and argon. When the temperature inside the heat treatment furnace is below 500 °C, nitrogen is introduced; when the temperature inside the heat treatment furnace is above 500 °C, argon is introduced.

[0077] In the prior art, only one kind of inert gas is introduced during the heat treatment process of the nanocrystalline magnetic core. And for cost consideration, nitrogen is often only used. However, when the temperature is above 500 °C, nitrogen will produce nitrogen oxides, causing the magnetic core to be oxidized into light blue, resulting in serious oxidation of the magnetic core, a significant decrease in the low-frequency magnetic permeability. Compared with the prior art, in this application, nitrogen or argon is flexibly selected according to the temperature inside the heat treatment furnace, which can better protect the magnetic core material from oxidation or other chemical reactions. Moreover, this application utilizes the characteristics that nitrogen and argon have different protection effects at different temperatures, making the protection effect more accurate and efficient, effectively reducing the surface contamination and the formation of oxide layers of the magnetic core, thereby improving the quality and electrical performance of the magnetic core.

[0078] S4.2: After the temperature rises to the starting temperature, place the entire fixture 2 inside the cavity.

[0079] S4.3: Set at least one preset temperature node, gradually increase the temperature in sequence and maintain it for a period of time until the last preset temperature node is reached.

[0080] In this application, the last preset temperature node is set such that the temperature inside the heat treatment furnace is 480 °C and maintained for 12 hours. Meanwhile, a magnetic field is added to the cavity. By operating in this way, the atoms inside the magnetic core material have sufficient time and energy to rearrange and adjust their structures, optimize their microstructures, improve their magnetic properties and mechanical properties, help eliminate internal stress and defects in the material, improve the uniformity and consistency of the magnetic core, so as to ensure that the magnetic core material reaches a stable crystal structure state, thereby improving its stability during use.

[0081] S4.4: Cool down to a cooling temperature node.

[0082] Specifically, when the magnet core raw material 11 that has completed curing and shaping is taken out of the heat treatment furnace, the temperature of the nanocrystalline magnetic core remains above 300 °C. In this application, by taking out the magnetic core at a certain high temperature, the remaining heat can be used for subsequent surface treatment or other steps that require heat assistance, thereby improving energy efficiency and processing efficiency. In addition, the thermal stress generated due to rapid temperature change can be reduced, thereby reducing the risk of magnetic core cracking or deformation and ensuring the quality and performance of the magnetic core.

[0083] During application, by first evacuating the cavity of the heat treatment furnace and then introducing an inert gas, chemical reactions between the magnetic core material and oxygen or other reactive gases in the air during the heat treatment process can be effectively reduced to ensure the purity and performance stability of the magnetic core; by setting multiple preset temperature nodes, gradually increasing the temperature in sequence, and adding a magnetic field at a specific temperature, this treatment method can finely control the microstructure and magnetic properties of the magnetic core, realize the transformation from amorphous nanocrystalline magnetic core to nanocrystalline magnetic core. Moreover, the gradual increase in temperature during the heat treatment process helps reduce the thermal stress of the magnetic core to prevent cracks or deformation of the magnetic core during the heat treatment process. Finally, cool down to a cooling temperature node to ensure that the magnetic core can cool slowly after heat treatment, avoiding internal stress generated due to rapid cooling and further ensuring the quality and performance of the magnetic core.

[0084] S5: Impregnation treatment: Place the heat-treated laminated combined structure 1 in a vacuum pressure impregnation device for impregnation treatment.

[0085] S6: Curing and Shaping: Bake and cure the impregnated laminated composite structure 1, then disassemble the laminated composite structure 1 from the fixture 2, and then disassemble the cured and shaped magnetic core raw material 11, the first pressing piece 12, the second pressing piece 13, and the core 14. The cured and shaped magnetic core raw material 11 is formed into a nanocrystalline magnetic core.

[0086] Specifically, first immerse the laminated composite structure 1 in the hardening liquid for 1 minute. The hardening liquid can fill the tiny pores inside the material, and then drain it for 30 minutes until the hardening liquid penetrates into the microstructure of the magnetic core raw material 11, which helps to improve the density and mechanical properties of the material. In the processing step of S6, place the impregnated laminated composite structure 1 in a drying furnace for baking. The temperature in the drying furnace is 140°C and it is maintained for 10 hours, which can ensure that the hardening liquid is uniformly cured inside the magnetic core to form a stable structure.

[0087] S7: Surface Treatment: Remove the redundant insulating paint on the surface of the nanocrystalline magnetic core, and perform surface loss reduction treatment and surface protection treatment on the nanocrystalline magnetic core to obtain the finished magnetic core.

[0088] Specifically, perform spraying treatment according to 20 - 30 on the surface of the nanocrystalline magnetic core. Through the spraying treatment, a uniform and dense protective layer can be formed on the surface of the nanocrystalline magnetic core. The protective layer can effectively isolate oxygen, moisture, and other corrosive substances in the external environment, thereby extending the service life of the magnetic core. And controlling the spraying thickness within the range of 20 - 30μm can ensure that the protective layer has sufficient thickness to provide good protection effect and help reduce production costs.

[0089] In this application, through strict screening of the magnetic core raw material 11 to ensure the quality of the raw material, without burrs, dry, and the thickness within the specified range, which helps to ensure the performance and stability of the final product. Adopting the method of lamination and shaping enables multiple magnetic core raw materials 11 to be stacked tightly and neatly together. At the same time, through the end face flattening treatment, the flatness and consistency of the magnetic core raw material 11 are ensured. Affected by the material of the magnetic core raw material 11, the magnetic core raw material 11 deforms after being subjected to pressure, turning the circular magnetic core into a rectangular magnetic core. Through heat treatment, the internal organizational structure of the magnetic core can be improved, and its mechanical properties and magnetic properties can be enhanced. The impregnation treatment can enhance the insulation performance and corrosion resistance of the magnetic core, and the baking and curing make the impregnated layer adhere more firmly to the surface of the magnetic core to improve the durability and reliability of the magnetic core, thereby realizing the transformation from the amorphous nanocrystalline magnetic core to the nanocrystalline magnetic core, while maintaining the shape and not restoring deformation. Finally, by removing the redundant insulating paint, performing surface loss reduction treatment and surface protection treatment, the surface quality of the magnetic core is further optimized, which helps to reduce the losses caused by friction and corrosion during use.

[0090] Compared with the prior art, after processing steps such as incoming material inspection, laminating and sizing, end face flattening, heat treatment, dipping treatment, curing and sizing, and surface treatment, it is possible to achieve batch processing of the magnetic core raw material 11, enabling it to be transformed from an easily producible annular structure into a rectangular structure. Moreover, the mechanical properties of the transformed structure are stable, and it is not prone to springback. The finished product has good quality, and the magnetic flux path of the rectangular magnetic core also becomes uniform. After the above steps of processing, it can ensure the convenience of processing the amorphous nanocrystalline magnetic core, while making the magnetic flux path of the magnetic core uniform, reducing the winding difficulty, enhancing the performance of the magnetic core, and meeting the production requirements.

[0091] The above are all preferred embodiments of the present application. This embodiment is only an explanation of the present application and does not limit the protection scope of the present application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for preparing a square nanocrystalline magnetic core common mode inductor, characterized in that: The construction steps include: S1: Incoming material inspection: The surface of each magnetic core material (11) is free of burrs and kept dry, and the single-side thickness of the magnetic core material (11) is controlled within the specified range; S2: stacking and shaping: inserting the core (14) into the first pressing sheet (12), stacking a plurality of the magnetic core materials (11) on the first pressing sheet (12) in sequence, placing the core (14) in the middle of the magnetic core materials (11), then taking a second pressing sheet (13) and arranging it at an end away from the first pressing sheet (12), and plugging the second pressing sheet (13) and the core (14) into each other to obtain a stacked composite structure (1); S3: end surface flattening: placing the plurality of the stacked combined structures (1) in sequence in the fixture (2), spacing two adjacent stacked combined structures (1) by means of a clamping plate, and performing a flattening process on the end surfaces of the plurality of stacked combined structures (1) simultaneously by means of a material pressing assembly (4); S4: heat treatment: placing the laminated composite structure (1) in a heat treatment furnace for heat treatment; S5: varnishing treatment: placing the laminated composite structure (1) after the heat treatment in a vacuum pressure varnishing device for varnishing treatment; S6: Curing and shaping: the laminated composite structure (1) after the varnish dipping is baked and cured, then the laminated composite structure (1) is disassembled from the fixture (2), and then the cured and shaped magnetic core raw material (11), the first pressing sheet (12), the second pressing sheet (13), and the core (14) are decomposed, and the cured and shaped magnetic core raw material (11) is formed into a nanocrystalline magnetic core; S7: surface treatment: removing redundant insulating paint on the surface of the nanocrystalline magnetic core, and performing surface loss reduction treatment and surface protection treatment on the nanocrystalline magnetic core to obtain the finished magnetic core; In the processing step S2, the first pressed sheet (12) and the second pressed sheet (13) have the same shape and structure, and are twice the weight of the magnetic core raw material (11); The core (14) comprises at least two core bodies, the core bodies are detachably connected to each other, and the core (14) presents a rectangular structure as a whole; The core (14) comprises a first core body (141), a second core body (142) and a third core body (143); the first core body (141) and the second core body (142) are right-angled trapezoidal structures of the same shape and size; the third core body (143) is an isosceles trapezoidal structure; the first core body (141), the second core body (142) and the third core body (143) are arranged at the same height; in the processing step S2, one waist surface of the third core body (143) abuts against the inclined surface of the first core body (141), and the other waist surface of the third core body (143) abuts against the inclined surface of the second core body (142); the three are assembled to form a rectangular structure; the outer edges of the first core body (141) and the second core body (142) are both rounded and abut against the inner wall of the magnetic core material (11); The inclined surface of the first core body (141) and the inclined surface of the second core body (142) are respectively provided with guide grooves, and correspondingly, guide blocks are respectively fixed on the two waist surfaces of the third core body (143); when the first core body (141), the second core body (142) and the third core body (143) are assembled, the two guide blocks are respectively adapted and slidably connected with the guide grooves adjacent thereto, so that the gap between the first core body (141) and the third core body (143), and the gap between the second core body (142) and the third core body (143) tend to zero; An installation groove and a slide groove are provided inside the third core (143); the extension direction of the installation groove is consistent with the length direction of the third core (143); there are two slide grooves and they are symmetrically arranged along the center line of the installation groove; the slide groove penetrates from the end of the installation groove toward the first core (141) or the second core (142); correspondingly, an extension groove is provided at a position of the first core (141) close to the slide groove and at a position of the second core (142) close to the slide groove, respectively; the extension groove and the slide groove are on the same extension line; A lifting rod (144) is arranged in the installation groove, and the lifting rod (144) includes a lifting part (1441), a connecting part (1442) and a plug-in part (1443), wherein the lifting part (1441) is assembled with the connecting part (1442) via a bearing, and there are two plug-in parts (1443), which are respectively fixed on both sides of the connecting part (1442), and the plug-in part (1443) includes two nodes, and the nodes and the connecting part (1442) are fixed by hinges. The nodes of the plug-in portion (1443) away from the connecting portion (1442) are respectively slidably connected with the sliding grooves close thereto. In addition, an external thread is provided on the outer wall of one end of the lifting portion (1441) away from the connecting portion (1442), and the end of the lifting portion (1441) provided with the external thread faces the large end of the third core body (143).

2. The method for preparing a square nanocrystalline magnetic core common mode inductor according to claim 1, characterized in that: The processing step of S4 includes the following steps: S4.1: first evacuate the cavity of the heat treatment furnace, and then introduce inert gas into the cavity; S4.2: When the temperature reaches the starting temperature, placing the entire fixture (2) in the cavity; S4.3: setting at least one preset temperature node, gradually increasing the temperature in sequence, and maintaining the temperature for a period of time until the last preset temperature node is reached; at the same time, adding a magnetic field to the cavity; S4.4: Cool down to a cooling temperature node.

3. The method for preparing a square nanocrystalline magnetic core common mode inductor according to claim 2, characterized in that: The inert gas includes nitrogen and argon. In the processing step S4.1, when the temperature in the heat treatment furnace is below 500° C., nitrogen is introduced; when the temperature in the heat treatment furnace is above 500° C., argon is introduced.

4. The method for preparing a square nanocrystalline magnetic core common mode inductor according to claim 2, characterized in that: In the processing step S4.3, the temperature in the heat treatment furnace is maintained at 480° C. for 12 hours.

5. The method for preparing a square nanocrystalline magnetic core common mode inductor according to claim 2, characterized in that: In the processing step S4.4, when the magnetic core raw material (11) is taken out of the heat treatment furnace after solidification, the temperature of the nanocrystalline magnetic core is maintained above 300°C.

6. A method for preparing a square nanocrystalline magnetic core common mode inductor according to any one of claims 1 to 5, characterized in that: In the processing step S5, the laminated composite structure (1) is first immersed in a hardening liquid for 1 minute, and then drained for 30 minutes until the hardening liquid penetrates into the microstructure of the magnetic core raw material (11); in the processing step S6, the laminated composite structure (1) after varnishing is placed in a drying furnace for baking, and the temperature in the drying furnace is maintained at 140° C. for 10 hours.

7. A method for preparing a square nanocrystalline magnetic core common mode inductor according to any one of claims 1 to 5, characterized in that: In the processing step S7, the spraying treatment is performed according to the surface thickness of the nanocrystalline magnetic core being controlled within the range of 20-30 μm.

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