A nanocrystalline strip-wound iron core integrally injection-molded and a preparation method thereof

Abstract

The present invention belongs to the technical field of soft magnetic materials, and particularly relates to an integrally injection-molded nanocrystalline strip-wound iron core and a preparation method thereof. The preparation method comprises the following steps: annealing and crystallizing and stress-relieving an amorphous nanocrystalline strip, winding it into a closed magnetic circuit, then immersing it in an adhesive resin solution, taking it out and heating and curing it to form a magnetic core; putting the obtained magnetic core into a hard shell, then inserting a copper bar, and finally completing the plastic part between the magnetic core and the copper bar through injection molding to obtain an integrally injection-molded nanocrystalline strip-wound iron core. The method of the present invention can realize the integrally injection molding of the magnetic core, the copper bar and the plastic part. By further optimizing the adhesive resin solution system used for curing, the curing effect can be significantly improved and the magnetic properties of the iron core can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of soft magnetic materials, and particularly relates to a nanocrystalline strip-wound iron core formed by integral injection molding and a preparation method thereof. Background Art

[0002] With the increasing integration of power modules in the field of new energy vehicles, the volume requirements for each component are becoming more and more extreme. In traditional filter circuits, the connecting copper bars and plastic parts in the circuit are usually injection-molded first, and then assembled with a magnetic core with a protective box, or a magnetic core without a protective box is placed in the shell of the injection-molded part and fixed with glue to complete the assembly. This structure has a large volume and requires a lot of assembly work.

[0003] The existing preparation methods for nanocrystalline strip iron cores generally involve winding the strip into a closed magnetic circuit and then curing it by dipping in glue. For example, the Chinese patent application document with the publication number CN114927303A discloses a nanocrystalline magnetic core. The straight strip after thermal stress treatment is wound into an annular magnetic core by an automatic winding machine, and then subjected to nanocrystallization heat treatment and magnetic field heat treatment. Finally, it is placed in a plastic protective box to obtain a high magnetic induction nanocrystalline inductance magnetic core. However, nanocrystalline strips have the defects of being fragile and having poor flexibility. Although pre-stress relief treatment can reduce deformation and cracks to a certain extent, the tightness and uniformity of the magnetic core formed by winding still need to be further improved. The anti-stress deformation performance after dipping and curing is relatively low, and it is difficult to withstand the pressure during integral injection molding, and cracks and air gaps are likely to occur, affecting the magnetic permeability of the magnetic core. Summary of the Invention

[0004] Aiming at the above-mentioned shortcomings and deficiencies of the prior art, the primary object of the present invention is to provide a preparation method for a nanocrystalline strip-wound iron core formed by integral injection molding.

[0005] Another object of the present invention is to provide a nanocrystalline strip-wound iron core prepared by the above method.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] A preparation method for a nanocrystalline strip-wound iron core formed by integral injection molding includes the following preparation steps:

[0008] (1) Annealing, crystallizing and stress-relieving the amorphous nanocrystalline strip, winding it into a closed magnetic circuit, then immersing it in an adhesive resin solution, taking it out and heating it to cure and form a magnetic core;

[0009] (2) Putting the magnetic core obtained in step (1) into a hard shell, then inserting a copper bar, and finally completing the plastic part between the magnetic core and the copper bar by injection molding to obtain a nanocrystalline strip-wound iron core formed by integral injection molding.

[0010] Furthermore, the amorphous nanocrystalline strip used in step (1) is an amorphous nanocrystalline strip with a thickness of 10 - 30 μm and a composition system of FeSiB, FeSiBC, FeNiSiB, FeCuNbSiB, FeNiCuNbSiB, FeCoCuNbSiB, FeCuMoSiB, FeNiCuMoSiB, FeCoCuMoSiB, FeCuPCSiB, FeNiCuPCSiB, or FeCoCuPCSiB.

[0011] Furthermore, the specific steps of the annealing crystallization, stress relief treatment, and winding into a closed magnetic circuit in step (1) are as follows: First, wind the amorphous nanocrystalline strip into a closed magnetic circuit, and then perform isothermal magnetic field annealing crystallization and stress relief treatment at a temperature of 400 - 650 °C in the presence of a magnetic field.

[0012] Furthermore, the specific steps of the annealing crystallization, stress relief treatment, and winding into a closed magnetic circuit in step (1) are as follows:

[0013] Feed the amorphous nanocrystalline strip into a roll-to-roll annealing device and convey it through a pressure roller. At the same time, set a linear laser heating device, an electromagnetic induction heating device, or a Joule heat treatment device along the width direction of the strip on one or both sides of the strip. During the conveyance of the strip, perform linear dynamic crystallization annealing and stress relief treatment, and then wind it into a closed magnetic circuit.

[0014] Furthermore, the laser heating device is a laser with a power of 50 - 2000 W. The high-energy laser beam emitted by the laser performs a line scan along the width direction of the strip, and the strip in the area where the laser beam exits the beam region rapidly undergoes nanocrystallization and stress relief annealing. The electromagnetic induction heating device is a flat induction heating coil with a power of 50 - 10000 W. The strip passing through the induction heating coil region rapidly undergoes nanocrystallization and stress relief annealing. The Joule heat treatment device is a pair of carbon brush electrodes arranged on both sides along the width direction of the strip, and the carbon brush electrodes output a current with an intensity of 1 - 200 A by a DC power supply. The area where the current flows completes the rapid nanocrystallization and stress relief annealing of the strip.

[0015] Through the above local linear dynamic heat treatment process, the controllability of the crystallization process can be improved, and the exothermic aggregation during crystallization can be effectively reduced, thereby effectively improving the soft magnetic properties of the material.

[0016] Furthermore, the closed magnetic circuit described in step (1) is circular, rectangular, or racetrack-shaped.

[0017] Further, the adhesive resin solution in step (1) is an epoxy resin solution, a polyurethane resin solution, a polyacrylate resin solution or a silicone resin solution. More preferably, it is a silicone resin solution. The use of the silicone resin solution in the present invention has better high temperature resistance and flexibility compared with epoxy resin and other solutions, and the magnetic core after dipping and curing has better high temperature and high pressure stress deformation resistance.

[0018] Further, the epoxy resin solution includes an epoxy resin matrix and an epoxy resin curing agent, and the epoxy resin curing agent is one of an amino resin, ethylenediamine, m-phenylenediamine, maleic anhydride, dicyandiamide; the polyacrylate resin solution includes a polyacrylate resin matrix and a polyacrylate curing agent, and the polyacrylate curing agent is one of an isocyanate, aziridine, aluminum acetylacetonate; the silicone resin solution includes vinyl polysiloxane and hydrogen-containing polysiloxane, or the silicone resin solution includes epoxy group polysiloxane and amino group polysiloxane.

[0019] Further preferably, the epoxy group polysiloxane is prepared by the following method:

[0020] Mix hydrogen-containing silicone oil, allyl glycidyl ether and an organic solvent evenly, and then add a chloroplatinic acid isopropanol solution catalyst and heat for reaction to obtain epoxy group polysiloxane.

[0021] Preferably, the number average molecular weight of the hydrogen-containing silicone oil is 1000 - 10000, and the hydrogen content is 0.2 - 1 wt.%; the dosage of allyl glycidyl ether is 5% - 30% of the mass of the hydrogen-containing silicone oil; the organic solvent is one or more of N,N-dimethylformamide, toluene, xylene, ethyl acetate, butyl acetate, n-hexane, n-heptane, acetone, butanone, tetrahydrofuran, isopropanol; the dosage of the organic solvent is 5% - 20% of the total mass of the hydrogen-containing silicone oil and allyl glycidyl ether; the temperature of the heating reaction is 70 - 90 °C, and the time is 1 - 6 h.

[0022] Further preferably, the amino mass percentage content of the amino group polysiloxane is 0.2% - 2%, and the viscosity is 50 - 1000 cps.

[0023] The present invention adopts the curing adhesive solution system of the above-mentioned epoxy group polysiloxane and amino group polysiloxane. Compared with the curing adhesive solution system of vinyl polysiloxane and hydrogen-containing polysiloxane, it has better adsorption and adhesion to the nanocrystalline ribbon, can better penetrate into the gaps between the winding ribbon layers and achieve higher bonding force, so as to achieve better bonding and curing effect and stress deformation resistance.

[0024] Further, the temperature of the heating and curing molding in step (1) is 60 - 220 °C.

[0025] Further, the temperature of the injection molding in step (2) is 120~360°C, and the pressure is 30~300 MPa.

[0026] Further, the material of the hard shell in step (2) is aluminum alloy, ferroalloy or plastic.

[0027] A nanocrystalline ribbon-wound iron core is prepared by the above method.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The magnetic core of the present invention is obtained by impregnating and curing a nanocrystalline ribbon after annealing crystallization and stress relief treatment, which can better resist the high-temperature and high-pressure stress deformation during the injection molding process, enabling it to achieve integral injection molding with copper bars and plastic parts.

[0030] (2) By further optimizing the adhesive resin solution system for curing, the present invention can significantly improve the curing effect and the magnetic properties of the iron core. Description of the Drawings

[0031] Figure 1 is a schematic structural diagram of the nanocrystalline ribbon-wound iron core obtained in Example 1 of the present invention;

[0032] Figure 2 is a schematic diagram of the finished product after integral injection molding of the magnetic core, plastic parts and copper bars in Example 1 of the present invention;

[0033] Figure 3 and Figure 4 is a schematic flow diagram of the linear dynamic crystallization annealing treatment in Example 2 of the present invention. Detailed Embodiments

[0034] The present invention will be further described in detail below with reference to the embodiments, but the embodiments of the present invention are not limited thereto. Example 1

[0035] A preparation method of an integrally injection-molded nanocrystalline ribbon-wound iron core includes the following preparation steps:

[0036] (1) A non-crystalline nanocrystalline ribbon with a thickness of 18 μm and a composition of Fe 73.5 Cu 1 Nb 3 Si 15.5 B 7 (at.%) is wound into a racetrack-shaped closed magnetic circuit, and then placed in a heating furnace and heated to 560°C and subjected to isothermal magnetic field annealing crystallization and stress relief treatment for 1.5 h in the presence of a magnetic field to obtain a nanocrystalline ribbon magnetic core.

[0037] (2) Immerse the nanocrystalline ribbon core obtained in step (1) into bisphenol A liquid epoxy resin adhesive (using ethylenediamine as the curing agent, commercially available) for 30 min. After taking it out, heat it to 120 °C in a curing furnace for curing and forming to obtain the core.

[0038] (3) Put the core obtained in step (2) into an aluminum alloy hard shell, then insert the copper bar, and finally complete the plastic part between the core and the copper bar by injection molding (injection temperature 280 °C, pressure 50 MPa) to obtain an integrally injection-molded nanocrystalline ribbon wound core.

[0039] The structural schematic diagram of the integrally injection-molded nanocrystalline ribbon wound core obtained in this embodiment and the schematic diagram of the finished product after integral injection molding are respectively as Figure 1 and Figure 2 shown. Example 2

[0040] A preparation method of an integrally injection-molded nanocrystalline ribbon wound core. Compared with Example 1, a linear dynamic crystallization annealing and stress relief treatment method is used to replace the isothermal magnetic field annealing crystallization and stress relief treatment, and it includes the following preparation steps:

[0041] (1) Add an amorphous nanocrystalline ribbon with a thickness of 18 μm and a composition of Fe 73.5 Cu 1 Nb 3 Si 15.5 B 7 (at.%) into a roll-to-roll annealing device and convey it through a pressure roller. The conveying speed of the pressure roller is 6 m / min. At the same time, a linear laser heating device along the width direction of the ribbon is arranged on one side of the ribbon. During the conveying process of the ribbon, a high-energy laser beam with a power of 1000 W is synchronously turned on to perform line scanning along the width direction of the ribbon, and the ribbon in the laser beam outflow area quickly undergoes nanocrystallization and stress relief annealing. The corresponding processing flow schematic diagrams are as Figure 3 and Figure 4 shown.

[0042] (2) Wind the nanocrystalline ribbon obtained after the treatment in step (1) into a racetrack-shaped closed magnetic circuit, and then immerse it into bisphenol A liquid epoxy resin adhesive (using ethylenediamine as the curing agent, commercially available) for 30 min. After taking it out, heat it to 120 °C in a curing furnace for curing and forming to obtain the core.

[0043] (3) Put the core obtained in step (2) into an aluminum alloy hard shell, then insert the copper bar, and finally complete the plastic part between the core and the copper bar by injection molding (injection temperature 280 °C, pressure 50 MPa) to obtain an integrally injection-molded nanocrystalline ribbon wound core. Example 3

[0044] A preparation method of a nanocrystalline strip-wound core by integral injection molding. Compared with Example 1, polyacrylate resin solution (using isocyanate as a curing agent, commercially available) is used to replace the epoxy resin solution, and the heating curing temperature is 100 °C, and the rest is the same. Example 4

[0045] A preparation method of a nanocrystalline strip-wound core by integral injection molding. Compared with Example 1, an organosilicon resin solution composed of vinyl polysiloxane (vinyl content 6.2 wt%, viscosity 500 cps) and hydrogen-containing polysiloxane (hydrogen content 0.5%, viscosity 100 cps) in a mass ratio of 2:1 (containing a catalytic amount of platinum complex catalyst and an appropriate amount of alkynol stabilizer, commercially available) is used to replace the epoxy resin solution, and the heating curing temperature is 90 °C, and the rest is the same. Example 5

[0046] A preparation method of a nanocrystalline strip-wound core by integral injection molding. Compared with Example 1, an organosilicon resin solution composed of epoxy group-containing polysiloxane (epoxy group content 6.2 wt%, viscosity 500 cps) and amino group-containing polysiloxane (amino group content 0.5%, viscosity 100 cps, commercially available) in a mass ratio of 2:1 is used to replace the epoxy resin solution, and the heating curing temperature is 100 °C, and the rest is the same.

[0047] The epoxy group-containing polysiloxane is prepared by the following method:

[0048] By mass, 100 parts of hydrogen-containing silicone oil with a number average molecular weight of 5600 and a hydrogen content of 0.52 wt.%, 20 parts of allyl glycidyl ether, and 10 parts of toluene are mixed evenly. Under nitrogen protection, a solution catalyst of chloroplatinic acid isopropyl alcohol with a platinum content of 50 ppm is added and heated to 80 °C for stirring reaction for 4 h to obtain epoxy group-containing polysiloxane with an epoxy group content of 6.2 wt% and a viscosity of 500 cps.

[0049] The relative permeability (100 kHz) of the wound cores obtained in the above examples was tested, and the results are shown in Table 1 below.

[0050] Table 1

[0051] Test group Magnetic permeability Example 1 24560 Example 2 31280 Example 3 26720 Example 4 28450 Example 5 35840

[0052] From the comparison results of Example 1 and Example 2 in Table 1, it can be seen that compared with the overall annealing process of a conventional heating furnace, the linear dynamic crystallization annealing treatment process adopted in the present invention can significantly improve the magnetic permeability. The reason is that the linear dynamic crystallization annealing treatment process can effectively reduce the aggregation of crystallization heat release, improve the controllability of the crystallization process, prevent grain coarsening, refine the nanocrystalline size and improve the uniformity, thereby effectively improving the magnetic permeability. From the comparison results of Example 4 and 5 with Example 1 and 3, it can be seen that using silicone resin glue has better high-temperature resistance and flexibility compared with conventional epoxy resin, acrylate resin and other glues. After dipping and curing, the magnetic core has better resistance to stress deformation during high-temperature and high-pressure injection molding. After one-piece injection molding, it can ensure good structural integrity and uniformity, reduce cracking and air gaps, so it can improve the magnetic permeability. From the comparison results of Example 4 and Example 5, it can be seen that using an impregnating and curing system composed of epoxy-based polysiloxane and amino polysiloxane can further significantly improve the magnetic permeability compared with an impregnating and curing system composed of vinyl polysiloxane and hydrogen-containing polysiloxane. The reason is that the adhesion and bonding properties of epoxy-based polysiloxane and amino polysiloxane to the nanocrystalline tape are better, and they can better penetrate into the gaps between the winding tape layers and achieve higher bonding force, so as to achieve better bonding and curing effects and resistance to stress deformation during injection molding.

[0053] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for preparing an integrally injection molded nanocrystalline ribbon wound core, characterized in that: The method comprises the following preparation steps: (1) The amorphous nanocrystalline strip is annealed, crystallized and stress-relieved and wound into a closed magnetic circuit, then immersed in an adhesive resin solution, taken out and heated and cured to obtain a magnetic core; (2) placing the magnetic core obtained in step (1) into a hard shell, then inserting a copper busbar, and finally completing the plastic part between the magnetic core and the copper busbar by injection molding to obtain an integrally injection-molded nanocrystalline ribbon wound iron core; The adhesive resin glue in step (1) is a silicone resin glue; the silicone resin glue comprises epoxy polysiloxane and amino polysiloxane; The epoxy polysiloxane is prepared by the following method: The hydrogen-containing silicone oil, allyl glycidyl ether and an organic solvent are mixed, and then a chloroplatinic acid isopropanol solution catalyst is added and heated to react to obtain epoxy polysiloxane; The number average molecular weight of the hydrogen-containing silicone oil is 1000-10000, and the hydrogen content is 0.2-1wt.%; the amount of allyl glycidyl ether is 5%-30% of the mass of the hydrogen-containing silicone oil; the organic solvent is one or more of N,N-dimethylformamide, toluene, xylene, ethyl acetate, butyl acetate, n-hexane, n-heptane, acetone, butanone, tetrahydrofuran, and isopropanol; the amount of the organic solvent is 5%-20% of the total mass of the hydrogen-containing silicone oil and allyl glycidyl ether; the temperature of the heating reaction is 70-90°C, and the time is 1-6h.

2. The method for preparing a one-piece injection-molded nanocrystalline ribbon wound core according to claim 1, characterized in that: The amorphous nanocrystalline ribbon described in step (1) has a thickness of 10-30 μm and a composition system of FeSiB, FeSiBC, FeNiSiB, FeCuNbSiB, FeNiCuNbSiB, FeCoCuNbSiB, FeCuMoSiB, FeNiCuMoSiB, FeCoCuMoSiB, FeCuPCSiB, FeNiCuPCSiB, FeCoCuPCSiB.

3. The method for preparing a nanocrystalline ribbon wound core formed by integral injection molding according to claim 1, characterized in that: The specific steps of annealing, crystallization and stress relief treatment and winding into a closed magnetic circuit in step (1) are as follows: the amorphous nanocrystalline strip is firstly wound into a closed magnetic circuit, and then isothermal magnetic field annealing, crystallization and stress relief treatment are performed under the conditions of 400~650℃ temperature and magnetic field.

4. The method for preparing a nanocrystalline ribbon wound core formed by integral injection molding according to claim 1, characterized in that: The specific steps of annealing, crystallization, stress relief treatment and winding into a closed magnetic circuit in step (1) are as follows: The amorphous nanocrystalline strip is added into the roll-to-roll annealing device and conveyed by the pressure rollers. At the same time, a linear laser heating device, an electromagnetic induction heating device or a Joule heat treatment device is arranged along the width direction of the strip on one or both sides of the strip. Linear dynamic crystallization annealing and stress relief treatment are performed during the conveying process of the strip, and then the strip is wound into a closed magnetic circuit.

5. The method for preparing a nanocrystalline ribbon wound core formed by integral injection molding according to claim 4, characterized in that: The laser heating device is a laser with a power of 50~2000W. The high-energy laser beam emitted by the laser performs line scanning along the width direction of the strip, and the strip in the area where the laser beam flows out of the beam rapidly undergoes nanocrystallization and stress relief annealing; the electromagnetic induction heating device is a flat induction heating coil with a power of 50~10000W. The strip in the area where the induction heating coil passes rapidly undergoes nanocrystallization and stress relief annealing; the Joule heat treatment device is a pair of carbon brush electrodes arranged on both sides of the strip in the width direction. The carbon brush electrodes are output with a current of 1~200A by a DC power supply, and the area where the current flows completes the rapid nanocrystallization and stress relief annealing of the strip.

6. The method for preparing an integrally injection-molded nanocrystalline ribbon wound core according to claim 1, characterized in that: The closed magnetic circuit in step (1) is annular, rectangular or racetrack-shaped.

7. The method for preparing an integrally injection-molded nanocrystalline ribbon wound core according to claim 1, characterized in that: The amino polysiloxane has an amino mass percentage of 0.2% to 2% and a viscosity of 50 to 1000 cps.

8. The method for preparing an integrally injection-molded nanocrystalline ribbon wound core according to claim 1, characterized in that: The temperature of the heating and curing molding in step (1) is 60~220℃.

9. The method for preparing an integrally injection-molded nanocrystalline ribbon wound core according to claim 1, characterized in that: The injection molding temperature in step (2) is 120-360° C. and the pressure is 30-300 MPa; the material of the hard shell is aluminum alloy, iron alloy or plastic.

10. A nanocrystalline ribbon wound core, characterized in that: It is prepared by the method according to any one of claims 1 to 9.

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