A method for low-stress waterproof packaging of a magnetic alloy ring

Abstract

The present application relates to soft magnetic material packaging technical field, especially to a kind of magnetic alloy ring low stress waterproof packaging method;Method includes steps: the inner diameter and outer diameter of magnetic alloy ring are supported using FRP pipe, silicon gel is coated in the two end surfaces of magnetic alloy ring to form SiO2 Film layer, epoxy resin and glass fiber cloth are used to SiO2 Film layer is wrapped to form solidified layer;Magnetic alloy ring wrapped by solidified layer is placed in mould, vacuum pressure epoxy impregnation process is used to inject solidified liquid to the inner cavity of mould, after heating solidification, mould is removed, realize magnetic alloy ring low stress waterproof packaging.Vacuum pressure epoxy impregnation process can effectively remove the gas in epoxy resin, the isolation layer formed after solidification is free from bubble and other defects, form reliable sealing layer;Before waterproof packaging, SiO2 Film layer formed on the surface of magnetic alloy ring, the penetration of epoxy resin in subsequent process implementation process is isolated, reduce the influence of process implementation on the high frequency performance of magnetic ring.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soft magnetic material packaging, in particular to a low-stress waterproof packaging method of magnetic alloy ring. BACKGROUND

[0002] Since a large amount of heat is generated in the magnetic ring when the magnetic alloy ring works at high repetition frequency and high duty cycle, the magnetic ring is generally cooled by directly immersing in circulating deionized water. In order to prevent rust and high-voltage discharge caused by the contact between the magnetic alloy ring and the deionized water, waterproof packaging treatment needs to be performed on the surface of the magnetic alloy ring.

[0003] However, the performance requirement of the magnetic ring used in the industry is not high, and the size is small, so the magnetic ring is generally immersed in epoxy resin, and the epoxy is fully penetrated into the interlayer gap of the magnetic ring by using ultrasonic technology. After the magnetic ring is air-dried and heated for curing, the obtained magnetic ring has good mechanical strength and waterproof characteristics, but the performance of the magnetic ring is severely reduced. The second commonly used process is a manual epoxy resin and glass fiber cloth curing process. The disadvantage is that due to the large area of the end face of the magnetic ring, the risk of air bubbles or pinholes in the magnetic ring is high, the thickness of the packaging layer is uncontrollable, the surface is uneven, and it is not suitable for use in high-end devices such as particle accelerators.

[0004] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0005] In view of the above problems in the prior art, the purpose of the present application is to provide a low-stress waterproof packaging method of magnetic alloy ring, which aims to solve the problems of the prior art, such as severe performance reduction of the magnetic ring, uncontrollable thickness of the packaging layer, air bubbles or pinholes in the packaging layer, and uneven surface.

[0006] The technical scheme of the present application is as follows:

[0007] A low-stress waterproof packaging method of magnetic alloy ring, comprising the steps of:

[0008] providing a magnetic alloy ring;

[0009] The inner diameter and outer diameter of the magnetic alloy ring are supported by FRP pipes, silicon gel is coated on the two end faces of the magnetic alloy ring to form a SiO2 film layer, and the SiO2 film layer is wrapped with epoxy resin and glass fiber cloth to form a cured layer.

[0010] The magnetic alloy ring wrapped with the cured layer is placed in a mold, a curing liquid is injected into the inner cavity of the mold by using a vacuum pressure epoxy impregnation process, and after heating and curing, the mold is removed, thereby realizing low-stress waterproof packaging of the magnetic alloy ring.

[0011] The low-stress waterproof packaging method of the magnetic alloy ring, wherein the preparation of the magnetic alloy ring comprises the steps of:

[0012] The application provides a nanocrystalline strip;

[0013] The nanocrystalline strip is coated with SiO2 on both sides, and the nanocrystalline strip coated with SiO2 is wound to obtain a magnetic alloy ring.

[0014] The application further provides a method for low-stress waterproof packaging of the magnetic alloy ring, wherein the thickness of the nanocrystalline strip is 17-19 μm, and the lamination coefficient of the magnetic alloy ring is 0.7-0.8.

[0015] The application further provides a method for low-stress waterproof packaging of the magnetic alloy ring, wherein the step of wrapping the SiO2 film layer with the epoxy resin and the glass fiber cloth to form a cured layer comprises the following steps:

[0016] The epoxy resin with a viscosity of 1.6×10 3 -22×10 3 cps and the curing agent with a viscosity of 40-60 cps are mixed in a mass ratio of 3:1 to obtain an epoxy mixture;

[0017] The epoxy mixture is coated on the surface of the SiO2 film layer within 3-4 hours at 25℃, then the glass fiber cloth is laid on the surface of the epoxy mixture, and the glass fiber cloth is cured at 115-125℃ for 50-60 minutes to form a cured layer.

[0018] The application further provides a method for low-stress waterproof packaging of the magnetic alloy ring, wherein the step of injecting the curing liquid into the inner cavity of the mold by using a vacuum pressure epoxy impregnation process and removing the mold after curing comprises the following steps:

[0019] The glass fiber cloth is placed in the gap between the magnetic alloy ring and the mold and vacuumized, the curing liquid is injected into the inner cavity of the mold and vacuumized, then nitrogen is filled into the inner cavity of the mold to pressurize, the mold is removed after curing by heating under the condition of maintaining the pressure, and an isolation layer is formed on the surface of the cured layer.

[0020] The application further provides a method for low-stress waterproof packaging of the magnetic alloy ring, wherein the curing liquid is obtained by degassing the mixture of the epoxy resin and the curing agent in a vacuum stirring degassing tank.

[0021] The application further provides a method for low-stress waterproof packaging of the magnetic alloy ring, wherein 0.1 MPa nitrogen is filled into the inner cavity of the mold, and the curing of the curing liquid is realized by maintaining the temperature at 130℃ for 10 hours.

[0022] The method for low-stress waterproof packaging of the magnetic alloy ring, wherein the mold comprises an upper pressing plate, side pressing blocks and a lower pressing plate; the upper pressing plate, the side pressing blocks and the lower pressing plate enclose a closed space which matches the magnetic alloy ring; a sealing ring is arranged between the upper pressing plate and the side pressing blocks, and a sealing ring is arranged between the lower pressing plate and the side pressing blocks; the side pressing blocks are provided with a center-symmetrical glue inlet and a glue outlet.

[0023] The method for low-stress waterproof packaging of the magnetic alloy ring, wherein the side pressing blocks are provided with a plurality of sealing grooves at the glue inlet and the glue outlet.

[0024] The method for low-stress waterproof packaging of the magnetic alloy ring, wherein the upper pressing plate, the side pressing blocks and the lower pressing plate form a closed space through locking nuts and sealing rings; and the upper pressing plate is provided with a lifting ring on the side away from the lower pressing plate.

[0025] Beneficial effects: The method for low-stress waterproof packaging of the magnetic alloy ring is provided, the inner diameter and the outer diameter of the magnetic alloy ring are supported by the FRP pipe, the silicon gel is coated on the surface of the magnetic alloy ring to form the SiO2 film layer, the SiO2 film layer is wrapped by the epoxy resin and the glass fiber cloth to form the solidified layer; the magnetic alloy ring wrapped by the solidified layer is placed in the mold, the vacuum pressure epoxy impregnation process is used to inject the solidified liquid into the inner cavity of the mold, the mold is removed after heating and solidification, and the low-stress waterproof packaging of the magnetic alloy ring is realized. The packaging layer of the magnetic alloy ring processed by using the method has the advantages of low stress, high mechanical strength, good sealing performance, high insulation and pressure resistance, etc. The glass fiber cloth belongs to the mechanical reinforcing material, forms the composite material isolation layer which is firm, wear-resistant and high in mechanical strength together with the epoxy resin, the vacuum pressure epoxy impregnation process can effectively remove the gas in the epoxy resin, the isolation layer formed after solidification is free of defects such as bubbles, and a reliable sealing layer is formed; and since the SiO2 film layer is formed on the surface of the magnetic alloy ring before waterproof packaging, the penetration of the epoxy resin is well isolated, and the influence of the epoxy resin on the performance of the magnetic ring can be effectively reduced; and the nanocrystalline strip is very sensitive to stress, and external stress can change the magnetic domain structure in the material, thereby affecting the material performance. The epoxy resin used in waterproof packaging will shrink obviously under high-temperature solidification, thereby producing stress, so the silicon gel primer layer is processed before the solidified layer in the present application, so that the subsequent epoxy resin does not directly act on the magnetic ring, the silicon gel is insulating and soft, has little influence on the magnetic ring, the size of the SiO2 or SiO particles formed after air drying of the silicon gel is large enough to fill the gaps of the magnetic ring, thereby realizing the low-stress packaging of the magnetic alloy ring. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of the packaging structure of the magnetic alloy ring.

[0027] Figure 2 is a top view of the mold in the present application;

[0028] Figure 3 is a cross-sectional view along Figure 2 line A-A in the present application;

[0029] Figure 4 is an exploded view of the mold in the present application. DETAILED DESCRIPTION

[0030] The present application provides a method for low-stress waterproof packaging of a magnetic alloy ring. To make the purpose, technical solution and effects of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0031] In the embodiments and the patent application scope, unless the article is specifically limited in the text, "one", "a", "said" and "the" can also include the plural form. If the description of "first", "second" and the like is involved in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features.

[0032] It should be further understood that the phrase "comprising" used in the specification of the present application means that the features, integers, steps, operations, elements and / or components exist, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components and / or their combinations. The phrase "and / or" used herein includes all or any unit and all combinations of the associated listed items.

[0033] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as that generally understood by those skilled in the art to which the present application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood as having meanings consistent with those in the prior art, and should not be interpreted with idealized or overly formal meanings unless specifically defined as such.

[0034] Nanocrystalline soft magnetic alloy (magnetic alloy) has high saturation magnetic induction (Bs>1.2T), low coercivity (Hc<0.5A / m), high magnetic permeability (μ e >10 4 ) and low high-frequency loss (P 0.5T / 20kHzMagnetic alloy has excellent magnetic properties such as high saturation magnetic induction (1.5T), high magnetic permeability (1.0-10.0), low core loss (50W / kg) and the like. Compared with soft magnetic materials such as amorphous and ferrite, magnetic alloy is more suitable for use in a high-frequency environment, and has been widely used in high-frequency components such as common-mode choke coils, high-frequency switching power supplies and high-frequency inverters. In recent years, the use of magnetic alloy strip wound to prepare a magnetic ring as an inductive loading material of a high-frequency cavity to enable the cavity to have a high acceleration gradient and a wide working frequency band has become a key technology of a high-power proton / heavy ion synchrotron. However, when the magnetic alloy ring is operated at a high repetition frequency and a high duty cycle, a large amount of heat is generated in the magnetic ring, and the magnetic ring is generally cooled by being directly immersed in circulating deionized water. In order to prevent rust and high-voltage discharge caused by the contact of the magnetic alloy ring with the deionized water, waterproof packaging treatment needs to be performed on the surface of the magnetic alloy disc.

[0035] In addition to waterproof, the packaging layer also needs to have high strength and low stress characteristics; the reasons include: 1. The magnetic alloy ring becomes brittle after high-temperature annealing, and the size of the magnetic ring used in the particle accelerator is often large, for example, the outer diameter of the magnetic ring used in the Japanese proton accelerator (J-PARC) and the Chinese spallation neutron source (CSNS) reaches 850mm, and the weight can reach more than 80kg, and the magnetic ring needs to be vertically placed, so the packaging layer needs to have sufficient strength to prevent the magnetic ring from deforming; 2. The magnetic alloy strip is very sensitive to stress, which can cause the performance of the magnetic ring to deteriorate, so the packaging needs to have the characteristics of low stress; 3. Due to the large size of the magnetic ring, the requirement for packaging defects is very high, and any possible defects, such as bubbles or pinholes in the packaging layer, can cause the magnetic ring to have surface electrical insulation breakdown or magnetic ring thermal stress deformation during high-power operation. Therefore, there is an urgent need to provide a magnetic alloy ring low-stress waterproof packaging method that can ensure that the packaging layer of the magnetic alloy ring has low stress, high mechanical strength, good sealing performance, high insulation voltage and the like.

[0036] Based on this, the present application provides a magnetic alloy ring low-stress waterproof packaging method, comprising the steps of:

[0037] Step S10: providing a magnetic alloy ring;

[0038] Step S20: the inner diameter and the outer diameter of the magnetic alloy ring are supported by an FRP tube, silicon gel is coated on the two end faces of the magnetic alloy ring to form a SiO2 film layer, and the SiO2 film layer is wrapped with epoxy resin and glass fiber cloth to form a cured layer;

[0039] Step S30: placing the magnetic alloy ring wrapped by the cured layer in a mold, injecting a curing liquid into the inner cavity of the mold by using a vacuum pressure ring epoxy impregnation process, removing the mold after heating and curing, and realizing low-stress waterproof packaging of the magnetic alloy ring.

[0040] In this embodiment, FRP pipes are arranged at the inner diameter and outer diameter of the magnetic alloy ring for supporting the magnetic alloy ring, then silica gel is coated on the two end faces of the magnetic alloy ring to form a coating layer containing large-particle SiO2, with a thickness of about 50 μm, for filling the gap of the end face of the magnetic alloy ring, preventing subsequent epoxy from penetrating into the gap between the strips, and also playing a certain insulation role on the end face; the second layer is a cured layer formed by high-viscosity epoxy resin and glass fiber cloth, mainly for preliminary shaping of the magnetic alloy ring; the SiO2 film layer and the cured layer serve as the composite primer layer of the magnetic alloy ring; the last layer is an isolation layer made of low-concentration epoxy resin and glass fiber cloth by vacuum pressure epoxy impregnation process, so that the magnetic ring has sufficient mechanical strength and waterproof effect while smoothing the surface of the magnetic ring; the low-concentration epoxy resin will wrap the entire magnetic alloy ring when cured, and the inner and outer diameter corner areas of the magnetic ring will also be adequately protected, and the entire curing process is completed in a vacuum chamber, the total thickness of the packaging layer (SiO2 film layer + cured layer + isolation layer) is about 1 mm, the thermal conductivity is about 0.5 W / m / K, and the maximum temperature resistance of the packaging layer reaches 150°C.

[0041] In some embodiments, the magnetic alloy ring is a bare ring after high-temperature annealing.

[0042] In this embodiment, the magnetic alloy ring is a large-size magnetic alloy ring, and the size of the large-size magnetic alloy ring is a magnetic alloy ring with an outer diameter exceeding 450 mm; in a specific embodiment, the size of the magnetic alloy ring is Φ850 mm x Φ316 mm x 25 mm.

[0043] In a preferred embodiment, the thickness of the FRP pipe is about 3 mm; which can provide better support for the magnetic alloy ring. Specifically, the thickness of the FRP pipe is 2.5 mm to 3.5 mm.

[0044] Specifically, after the magnetic alloy disc is annealed, composite primer treatment is performed before formal waterproof packaging, and the composite primer layer is composed of a SiO2 film layer and epoxy resin + glass fiber cloth; after the primer treatment is completed, a layer of epoxy mesh cloth is laid on the upper and lower magnetic alloy discs, and then installed in a steel hard film, and then epoxy resin is injected by vacuum pressure epoxy impregnation process (VPI process), and then heated and cured after the epoxy resin injection is completed; after the curing is completed, the steel hard film is removed, and a high-precision fully-closed isolation layer is obtained.

[0045] The packaging structure of the magnetic alloy disc is as follows Figure 1As shown, the nanocrystalline strip 20 coated with SiO2coating 10 is wound to form a magnetic alloy ring, the inner diameter and the outer diameter of the magnetic alloy ring are supported by FRP tube 30, and the surface of the magnetic alloy ring is first solidified with a SiO2film layer 40, then a solidification layer 50 is prepared on the surface of the SiO2film layer, and finally an isolation layer 60 is formed on the surface of the solidification layer; there is an air gap 70 between adjacent strips.

[0046] In some embodiments, in the step S10, the preparation of the magnetic alloy ring comprises the steps of:

[0047] Step S11: providing a nanocrystalline strip;

[0048] Step S12: coating SiO2coating on both sides of the nanocrystalline strip, after the SiO2coating is solidified, the nanocrystalline strip coated with SiO2coating is wound to obtain a magnetic alloy ring.

[0049] In this embodiment, Sol-Gel process is used to coat SiO2coating on both sides of the nanocrystalline strip, and the thickness of the SiO2coating is about 2 μm; the magnetic alloy ring is wound by nanocrystalline strips with a thickness of about 18 μm; in order to prevent the surface coating of the strip from falling off during winding due to excessive tension, the magnetic ring lamination factor is controlled at about 0.75, and there will be an air gap between adjacent strips, and the thickness of the air gap is about 2-3 μm; in order to prevent the curing agent from penetrating into the gap of the magnetic alloy ring and causing stress, in this embodiment, the SiO2coating (silica gel) with thickened viscosity (800-1200 mpa.s) is first brushed on the surface of the magnetic alloy ring; due to the high viscosity of the coating, the coating is not easy to penetrate into the interior of the magnetic ring, and the coating is solidified by circulating air at room temperature, and the solidified coating also has good insulation effect on the end face of the magnetic ring, making it more suitable for high electric field gradient application occasions.

[0050] In some embodiments, the thickness of the nanocrystalline strip is 17-19 μm; the lamination factor of the magnetic alloy ring is 0.7-0.8; the lamination factor of the magnetic alloy ring matches the thickness of the nanocrystalline strip, mainly to prevent the surface coating of the strip from falling off due to excessive tension during winding.

[0051] In some embodiments, in the step S20, the step of wrapping the SiO2film layer with epoxy resin and glass fiber cloth to form a solidification layer comprises:

[0052] Step S21: mixing epoxy resin with a viscosity of 1.6×10 3 -22×10 3 cps and a curing agent with a viscosity of 40-60 cps in a ratio of 3:1 to obtain an epoxy mixture;

[0053] Step S22: The epoxy mixture is coated on the surface of the SiO2 film layer within 3-4 hours at 25°C, and then the glass fiber cloth is laid on the surface of the epoxy mixture, and cured at 115-125°C for 50-60 minutes to form a cured layer.

[0054] Specifically, after the epoxy mixture is coated on the surface of the SiO2 film layer within 3-4 hours at 25°C, the glass fiber cloth with a thickness of about 60 microns is cut according to the shape of the magnetic alloy ring and laid in the epoxy mixture, and the cured layer is formed after curing; the main role of the cured layer is to preliminarily shape the magnetic alloy ring, which is convenient for subsequent preparation of the isolation layer.

[0055] In some embodiments, the thickness of the SiO2 film layer is 45-55 microns; as preferably, the thickness of the SiO2 film layer is 50 microns, which can be used to fill the gap of the end face of the magnetic alloy ring, hinder the subsequent epoxy from penetrating into the gap of the strip, and at the same time play a certain insulation role to the end face.

[0056] In some embodiments, in step S30, the step of injecting the curing liquid into the inner cavity of the mold by vacuum pressure epoxy impregnation process and removing the mold after curing, comprises: placing the glass fiber cloth in the gap between the magnetic alloy ring and the mold and vacuumizing, injecting the curing liquid into the inner cavity of the mold and continuing to vacuumize, then pressurizing the inner cavity of the mold by filling nitrogen, and removing the mold after heating and curing under pressure, to form an isolation layer on the surface of the cured layer; the isolation layer enables the magnetic alloy ring to have sufficient mechanical strength and waterproof effect, and at the same time can smooth the surface of the magnetic ring.

[0057] Specifically, in step S30, a glass fiber cloth with a thickness of about 350 microns and a grid size of 2.5 mm x 2.5 mm is used, and the glass fiber cloth with a thickness of about 350 microns is placed in the gap between the magnetic alloy ring and the mold, which can form a 350 micron gap for subsequent process of epoxy resin flow.

[0058] In some embodiments, the curing liquid is obtained by degassing the mixture of epoxy resin and curing agent in a vacuum stirring degassing tank; to ensure that the mixed curing liquid is bubble-free, after degassing, the curing liquid is injected into the inner cavity of the mold by using the vacuum existing in the mold, and the bubbles in the inner cavity of the mold are discharged after the curing liquid is injected and vacuumized for 30 minutes.

[0059] In some embodiments, after the bubbles in the inner cavity of the mold are discharged, 0.1 MPa nitrogen is filled into the inner cavity of the mold in reverse, so that the curing liquid in the mold is more compact, and then the curing liquid is cured under pressure at a temperature of 130°C for 10 hours.

[0060] The dense and bubble-free isolation layer formed by adopting vacuum pressure ring epoxy impregnation has excellent insulation and pressure resistance performance; and since the composite primer layer treatment is performed before waterproof packaging, the penetration of the epoxy resin is well isolated, so that the excellent high-frequency performance of the magnetic alloy ring is not affected.

[0061] Since the magnetic alloy ring requires that the total thickness of the packaging should be less than 1 mm and there should be no bubbles, in order to reduce the influence of the high thermal resistance of the packaging layer on the heat dissipation of the magnetic ring, and the defect rate (bubbles or pinholes) of the packaging layer should be controlled to a minimum, a special packaging process and structure need to be designed, therefore, in order to avoid the influence of residual bubbles in the solidification layer on the heat dissipation and waterproof effect of the magnetic ring and reduce the defect rate of the packaging layer, in some embodiments, as shown in Figures 2-4 The mold includes an upper pressing plate 110, a side pressing block 120, and a lower pressing plate 130; the upper pressing plate 110, the side pressing block 120, and the lower pressing plate 130 enclose a closed space which matches the magnetic alloy ring 140; a sealing ring 150 is arranged between the upper pressing plate 110 and the side pressing block 120, and a sealing ring 150 is arranged between the lower pressing plate 130 and the side pressing block 120; the side pressing block 120 is provided with a center-symmetric glue inlet 160 and a glue outlet 170.

[0062] Specifically, a layer of glass fiber cloth is first placed on the lower pressing plate, then the magnetic alloy ring and the side pressing block are placed, then a layer of glass fiber cloth is placed on the side of the magnetic alloy ring away from the lower pressing plate, and finally the upper pressing plate is covered, that is, the outer surface of the magnetic alloy ring is wrapped with a layer of glass fiber cloth 180; wherein a sealing ring 150 is arranged between the upper pressing plate and the side pressing block, and a sealing ring 150 is arranged between the lower pressing plate and the side pressing block; locking nuts 190 are used to fix the upper pressing plate, the side pressing block, and the lower pressing plate in sequence, so that the upper pressing plate, the side pressing block, and the lower pressing plate enclose a closed space, and the magnetic alloy ring is fixed in the closed space; finally, vacuum leak detection is performed to ensure that the mold does not leak.

[0063] In some embodiments, a plurality of sealing grooves 121 are arranged at the glue inlet and the glue outlet of the side pressing block 120, which serve as a sealing function when the mold is vacuumized.

[0064] In a specific embodiment, four sealing grooves are arranged at the glue inlet and the glue outlet of the side pressing block.

[0065] In some embodiments, the upper pressing plate, the side pressing block and the lower pressing plate form a closed space through the locking nut and the sealing ring; the upper pressing plate 110 is provided with a lifting ring 111 on the side away from the lower pressing plate 130; since the magnetic alloy ring has a large size, a lifting machine or other handling tools are needed for carrying, and the lifting ring is convenient for moving the mold by using the lifting tools.

[0066] In this embodiment, after the magnetic alloy ring is waterproofly packaged by the method for low-stress waterproof packaging of the magnetic alloy ring, relevant data are detected, and the detection is specifically as follows: Table 1 is the change of the performance of the magnetic ring at each process step directly measured by a network analyzer, wherein the performance of the magnetic ring is generally represented by μ' p Qf, wherein μ' p Qf is the product of the high-frequency loss Q value of the magnetic alloy material, the real part μ' p of the equivalent parallel permeability and the working frequency f, and represents the comprehensive high-frequency characteristics of the material and is irrelevant to the geometric size of the material. After the magnetic ring is packaged, the magnetic ring is placed in 0.3 MPa circulating deionized water for 31 days, and the change of μ' p Qf of the magnetic ring before and after soaking is measured to evaluate the waterproof effect of the magnetic ring. If water seeps into the inside of the magnetic ring, the water will cause a capacitive effect and thus the interlayer insulation of the material will be reduced, so that μ' p Qf value is reduced. The test data are shown in Table 2.

[0067] Table 1 Influence of stress at each process step of the magnetic ring solidification packaging on the performance of the magnetic ring

[0068] Test frequency (MHz) Before composite priming (GHz) After composite priming (GHz) After waterproofing encapsulation (GHz) 1 7.582 7.519 7.508 2 9.956 9.91 9.89 3 11.425 11.384 11.325 4 12.712 12.446 12.428 5 13.552 13.519 13.485

[0069] Table 2 Waterproof performance evaluation of the magnetic ring after packaging

[0070] Test frequency (MHz) Before waterproofing test (GHz) After waterproofing test (GHz) 1 7.508 7.495 2 9.89 9.81 3 11.325 11.282 4 12.428 12.395 5 13.485 13.403

[0071] In summary, the application provides a kind of magnetic alloy ring low stress waterproof packaging method, the inner diameter and outer diameter of magnetic alloy ring are supported using FRP pipe, silicon gel is coated on the surface of the magnetic alloy ring to form a SiO2 Thin film layer, and the SiO2 Thin film layer is wrapped using epoxy resin and glass fiber cloth to form a cured layer;The magnetic alloy ring wrapped by the cured layer is placed in a mold, a vacuum pressure epoxy impregnation process is used to inject curing liquid into the inner cavity of the mold, the mold is removed after heating and curing, and the magnetic alloy ring is packaged with low stress waterproof. The packaging layer of the magnetic alloy ring processed using the method has the advantages of low stress, high mechanical strength, good sealing performance, high insulation voltage strength and the like. Among them, the glass fiber cloth belongs to a mechanical reinforcing material, and forms a solid, wear-resistant, high-strength composite material isolation layer with the epoxy resin curing, and the vacuum pressure epoxy impregnation process can effectively remove the gas inside the epoxy resin, and the isolation layer formed after curing has no bubbles and other defects, forming a reliable sealing layer;And, since the SiO2 Thin film layer is formed on the surface of the magnetic alloy ring before waterproof packaging, the penetration of the epoxy resin is well isolated, and the influence of the epoxy resin on the performance of the magnetic ring can be effectively reduced.

[0072] It should be understood that the application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the application.

Claims

1. A method of low-stress, water-resistant encapsulation of a magnetic alloy ring, characterized by, The method comprises the steps of: providing a nanocrystalline strip; coating the nanocrystalline strip with a SiO2 coating on both sides, and after the SiO2 coating is cured, winding the nanocrystalline strip coated with the SiO2 coating to obtain a magnetic alloy ring; the magnetic alloy ring is a large-size magnetic alloy ring, and the size of the large-size magnetic alloy ring is a magnetic alloy ring with an outer diameter exceeding 450 mm; the inner diameter and the outer diameter of the magnetic alloy ring are supported by FRP pipes, silicon gel is coated on the two end faces of the magnetic alloy ring to form a SiO2 film layer, and the SiO2 film layer is wrapped with epoxy resin and glass fiber cloth to form a cured layer; the magnetic alloy ring wrapped with the cured layer is placed in a mold, a curing liquid is injected into the inner cavity of the mold by a vacuum pressure epoxy impregnation process, the mold is removed after curing by heating, and low-stress waterproof packaging of the magnetic alloy ring is realized; the thickness of the nanocrystalline strip is 17-19 μm; the lamination factor of the magnetic alloy ring is 0.7-0.8; the thickness of the FRP pipe is 2.5-3.5 mm; and the thickness of the SiO2 film layer is 45-55 μm; the step of injecting the curing liquid into the inner cavity of the mold by the vacuum pressure epoxy impregnation process and removing the mold after curing by heating comprises the following steps: placing glass fiber cloth in the gap between the magnetic alloy ring and the mold and vacuumizing, injecting the curing liquid into the inner cavity of the mold and continuing to vacuumize, then pressurizing by filling nitrogen into the inner cavity of the mold, removing the mold after curing by heating under the condition of maintaining pressure, and forming an isolation layer on the surface of the cured layer; the curing liquid is obtained by degassing the mixture of epoxy resin and curing agent in a vacuum stirring degassing tank; 0.1 MPa nitrogen is filled into the inner cavity of the mold, and the curing of the curing liquid is realized under the condition of maintaining the temperature at 130℃ for 10 hours.

2. The method of magnetic alloy ring low stress water resistant packaging of claim 1, wherein, the step of wrapping the SiO2 film layer with epoxy resin and glass fiber cloth to form a cured layer comprises: The epoxy resin with a viscosity of 1.6 x 10 3 22 x 10 3 cps and the curing agent with a viscosity of 40-60 cps are mixed in a mass ratio of 3:1 to obtain an epoxy mixture; at 25℃, the epoxy mixture is applied on the surface of the SiO2 film layer within 3-4 hours, then the glass fiber cloth is laid on the surface of the epoxy mixture, and the cured layer is formed by curing at 115-125℃ for 50-60 minutes.

3. The method of magnetic alloy ring low stress water resistant packaging of claim 1, wherein, the mold comprises an upper pressing plate, side pressing blocks and a lower pressing plate; the upper pressing plate, the side pressing blocks and the lower pressing plate enclose a closed space which matches the magnetic alloy ring; sealing rings are arranged between the upper pressing plate and the side pressing blocks and between the lower pressing plate and the side pressing blocks; the side pressing blocks are provided with centrally symmetric glue inlet and glue outlet.

4. The method of magnetic alloy ring low stress water resistant packaging of claim 3, wherein, sealing grooves are arranged at the glue inlet and the glue outlet of the side pressing blocks.

5. The method of magnetic alloy ring low stress water resistant packaging of claim 3, wherein, the upper pressing plate, the side pressing blocks and the lower pressing plate form a closed space through locking nuts and sealing rings; and a lifting ring is arranged on the side of the upper pressing plate away from the lower pressing plate.

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