Preparation process of elliptical ring-shaped nanocrystalline alloy core with high initial magnetic permeability

Abstract

The application discloses a preparation process of an elliptical ring-shaped nanocrystalline alloy iron core with high initial permeability, and comprises the following specific steps: S1, designing the iron core and a mold thereof; S2, winding amorphous alloy ribbons into a circular ring-shaped iron core according to the size and volume of the iron core; S3, placing the circular ring-shaped iron core into the mold; S4, placing the mold with the circular ring-shaped iron core into a vacuum annealing furnace to perform vacuum crystallization annealing; S5, after the annealing is completed, taking out the annealed circular ring-shaped iron core from the mold, placing the annealed circular ring-shaped iron core into an elliptical ring-shaped stainless steel protective box, and pouring silicon rubber to package the elliptical ring-shaped stainless steel protective box; and S6, measuring V-A characteristics by using an iron core performance measuring instrument, and calculating the initial permeability from the V-A data, compared with the prior art, the application offsets the deformation in the crystallization process by pre-deformation before annealing and mold shrinkage during the annealing process, greatly reduces internal stress, and obtains high initial permeability; uniform deformation of the elliptical ring-shaped iron core can be realized, and the elliptical ring shape is maintained after the annealing.

Description

Technical Field

[0001] This invention relates to the field of nanocrystalline alloys, and more specifically to the preparation process of elliptical ring-shaped nanocrystalline alloy cores with high initial magnetic permeability. Background Technology

[0002] Iron-based nanocrystalline alloys are a class of alloys with a nanocrystalline and amorphous dual-phase coupled structure obtained by crystallization annealing of amorphous alloys. They are currently the materials with the highest known magnetic permeability in the world. The preparation process of nanocrystalline alloy cores typically includes single-roll spinning to prepare amorphous alloy strips, winding and forming, vacuum crystallization annealing, packing into protective boxes, and performance testing.

[0003] The conventional shape of a nanocrystalline alloy core is a circular ring. However, in certain areas of the instrument transformer industry, an elliptical ring core is sometimes required. When an amorphous alloy is transformed into a nanocrystalline alloy during the vacuum crystallization annealing stage, a large number of free vacancies in the amorphous alloy disappear, resulting in a volume shrinkage of approximately 4%. If the core remains circular before and after annealing, the shrinkage is uniform across all parts, and the shape remains unchanged. If the core is elliptical before annealing, the shrinkage ratio of different parts during annealing is inconsistent. This may lead to the core not maintaining its elliptical ring shape after annealing, and residual stress may exist in the annealed core, resulting in a significant decrease in the initial permeability.

[0004] Currently, some companies in the industry use a method of winding a few millimeters thick cardboard around a fixed elliptical mold, then winding amorphous thin strips, and then sending the mold, cardboard, and amorphous alloy iron core together into a vacuum annealing furnace for high-temperature vacuum annealing. During the annealing process, the paper carbonizes, leaving space for the volume shrinkage when the amorphous alloy iron core crystallizes, which can produce an elliptical ring-shaped iron core with high magnetic permeability. However, this method leaves a large amount of tar and carbon black in the vacuum furnace, causing furnace pollution and environmental pollution.

[0005] Chinese patent CN208848746U discloses a mold for making a racetrack-shaped nanocrystalline alloy core, but this patent is not suitable for making an elliptical nanocrystalline alloy core, nor does it involve making an elliptical ring-shaped nanocrystalline alloy core with high initial permeability.

[0006] Chinese patent CN217640968U discloses an amorphous nanocrystalline iron core and a tooling assembly for manufacturing the iron core, which can produce an elliptical ring-shaped nanocrystalline alloy iron core. However, this patent does not involve the production of an elliptical ring-shaped nanocrystalline alloy iron core with high initial permeability, and the tooling assembly disclosed in this patent is also relatively complex.

[0007] With the development of the power industry, there is a need for high-precision current transformers with elliptical rings. Therefore, the amorphous industry needs to provide elliptical ring nanocrystalline alloy cores with high initial permeability. Conventional core products cannot meet market requirements. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a process for preparing an elliptical ring-shaped nanocrystalline alloy core with high initial permeability.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] The fabrication process of an elliptical toroidal nanocrystalline alloy core with high initial permeability includes the following specific steps: S1, designing the core and its mold; S2, winding the amorphous alloy strip into a toroidal core according to the core size and quantity; S3, placing the toroidal core into the mold; S4, placing the mold containing the toroidal core into a vacuum annealing furnace for vacuum crystallization annealing; S5, after annealing, removing the annealed toroidal core from the mold, placing it into an elliptical toroidal stainless steel protective box, and encapsulating it with silicone rubber; S6: measuring the VA characteristics using a core performance measuring instrument, and calculating the initial permeability from the VA data.

[0011] As a further preferred embodiment of the present invention, the outer perimeter of the iron core in step S1 is designed to be L1, and the outer perimeter of the annular iron core in step S2 is L2; ​​wherein L2 = L1 (1 + 1~2%).

[0012] As a further preferred embodiment of the present invention, the mold is made of TiNbO, and the inner circumference of the mold is equal to the outer circumference of the designed iron core.

[0013] As a further preferred embodiment of the present invention, the negative expansion coefficient of the TiNbO is -3.0 to -2.5 × 10⁻⁵.

[0014] As a further preferred embodiment of the present invention, the annular iron core is inserted into the mold by interference fitting.

[0015] As a further preferred embodiment of the present invention, the inner circumference of the stainless steel protective box is equal to the outer circumference of the designed iron core.

[0016] The advantages of this invention are: by pre-deformation before annealing and mold shrinkage during annealing, the deformation during crystallization is offset, the internal stress is greatly reduced, and a high initial magnetic permeability is obtained; it can achieve uniform deformation of the elliptical ring core, so that the elliptical ring shape is maintained after annealing; the mold is simple and the production efficiency is high. Attached Figure Description

[0017] Figure 1 It is an engineering drawing of an elliptical ring-shaped nanocrystalline alloy core;

[0018] Figure 2 This is a schematic diagram of the structure of an elliptical ring-shaped mold;

[0019] Figure 3 This is a schematic diagram of an elliptical ring-shaped protective box.

[0020] The meanings of the reference numerals in the figure are as follows: A1, outer circumference major semi-axis; B1, outer circumference minor semi-axis; t, thickness; h, height of the iron core; a2, inner circumference major semi-axis; b2, inner circumference minor semi-axis; t, thickness; h, height of the iron core; A3, outer wall major semi-axis; B3, outer wall minor semi-axis; a3, inner wall major semi-axis; b3, inner wall minor semi-axis; t, thickness; h, depth. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Example

[0022] Combination Figure 1 An elliptical nanocrystalline alloy core has the following dimensions: A1×B1×t×h, where the elliptical cross-sectional dimensions are: A1: outer major semi-axis, B1: outer minor semi-axis, t: thickness, and h: core height.

[0023] Combination Figure 2 An elliptical ring-shaped mold, with dimensions described as a2×b2×t×h, where the elliptical cross-section dimensions are: a2: inner major semi-axis, b2: inner minor semi-axis, t: thickness, and h: height of the iron core.

[0024] Combination Figure 3 An elliptical ring-shaped protective box, with dimensions described as: A3 / a3×B3 / b3×t×h, where the elliptical cross-sectional dimensions are: A3: outer wall major semi-axis, B3: outer wall minor semi-axis, a3: inner wall major semi-axis, b3: inner wall minor semi-axis, t: thickness, h: depth.

[0025] The fabrication process of an elliptical toroidal nanocrystalline alloy core with high initial permeability includes the following specific steps:

[0026] S1. Design the iron core and its mold.

[0027] An elliptical ring-shaped mold is made from a Ti-35%Nb-0.1%O alloy plate with a negative expansion coefficient of -3.0 to -2.5×10-5, a thickness of 2 to 4 mm, and a cold deformation of 95%; and the inner circumference of the mold is equal to the outer circumference of the designed iron core.

[0028] The required outer perimeter L1 of the elliptical iron core is calculated from the major semi-axis dimension A1 and the minor semi-axis dimension B1 of the elliptical toroidal iron core. L1 = 2πB1 + 4(A1 - B1).

[0029] S2. Based on the core size and allowance, the amorphous alloy strip is wound into a circular core.

[0030] In step S1, the outer perimeter of the iron core is designed to be L1, and in step S2, the outer perimeter of the annular iron core is designed to be L2; L2 = L1 (1 + 1~2%), and the thickness and height of the annular iron core and the elliptical annular iron core are the same.

[0031] The amorphous alloy is Fe73.5Si13.5B9Nb3Cu1.

[0032] S3. Place the annular iron core into the mold, and insert the annular iron core into the mold by interference fitting.

[0033] S4. Place the mold containing the annular iron core into a vacuum annealing furnace for vacuum crystallization annealing.

[0034] S5. After annealing, remove the annealed annular iron core from the mold and place it into an elliptical stainless steel protective box. The inner circumference of the stainless steel protective box is equal to the outer circumference of the designed iron core to ensure that the iron core can be easily installed into the stainless steel protective box. Silicone rubber is then poured in for encapsulation.

[0035] S6: The VA characteristics are measured using a core performance measuring instrument, and the initial permeability is calculated from the VA data.

[0036] The mold is made using a TiNbO cold-deformation alloy plate with a negative expansion coefficient of -3.0 to -2.5 × 10⁻⁵. Before annealing, the iron core is tightly fitted into the mold to achieve interference fit, causing a 1-2% pre-deformation in the core. Furthermore, during the annealing heating process, the iron core expands while the mold contracts, also causing approximately 2% deformation in the core. This offsets the approximately 4% shrinkage deformation that occurs when the amorphous alloy transforms into a nanocrystalline alloy. By offsetting the shrinkage deformation during the transformation, the internal stress in the elliptical ring-shaped nanocrystalline alloy iron core is reduced, resulting in an initial permeability greater than 160,000. Example

[0037] An elliptical nanocrystalline alloy iron core with dimensions of 76×63.5×8×25mm.

[0038] The specific plan is as follows:

[0039] S1: Calculate the required outer perimeter L1 of the elliptical iron core based on the major semi-axis dimension A1 and minor semi-axis dimension B1 of the elliptical toroidal iron core. L1 = 2πB1 + 4(A1 - B1) = 142.9 mm.

[0040] S2: A ring-shaped iron core with an outer circumference of 145.8 mm, a thickness of 8 mm, and a height of 25 mm is wound using an amorphous alloy strip with the composition of Fe73.5Si13.5B9Nb3Cu1.

[0041] S3: An elliptical ring-shaped mold is made from a Ti-34%Nb-0.1%O alloy plate with a negative expansion coefficient of -3.0×10-5, a thickness of 3mm, and a cold deformation of 95%. The dimensions of the elliptical ring are 76×63.5×3×30mm.

[0042] S4: Insert the iron core from S2 into the mold in S3 to achieve interference fit.

[0043] S5: Place the iron core and mold from S4 into a vacuum annealing furnace for vacuum crystallization annealing. The annealing process is 480℃ for 120 minutes + 550℃ for 120 minutes.

[0044] S6: Remove the annealed iron core from the mold.

[0045] S7: The annealed iron core is placed into a stainless steel protective box with dimensions of 77 / 67×64.5 / 54.5×0.8×30mm, and then sealed with 703 silicone rubber.

[0046] S8: The VA characteristics are measured using a core performance measuring instrument, and the initial permeability is calculated from the VA data.

[0047] When the input current is 25mA, the corresponding applied magnetic field strength is 0.08A / m, and the output electromotive force V is 0.58mV. The calculated initial permeability is 167,000. Example

[0048] An elliptical nanocrystalline alloy iron core with dimensions of 60×50×10×20mm.

[0049] The specific plan is as follows:

[0050] S1: Calculate the required outer perimeter L1 of the elliptical iron core based on the major semi-axis dimension A1 and minor semi-axis dimension B1 of the elliptical toroidal iron core. L1 = 2πB1 + 4(A1 - B1) = 112.7 mm.

[0051] S2: A ring-shaped iron core with an outer circumference of 113.9 mm, a thickness of 10 mm, and a height of 20 mm is wound using an amorphous alloy strip with the composition of Fe73.5Si13.5B9Nb3Cu1.

[0052] S3: An elliptical ring-shaped mold is made from a Ti-35%Nb-0.1%O alloy plate with a negative expansion coefficient of -2.5×10-5, a thickness of 2mm, and a cold deformation of 95%. The dimensions of the elliptical ring are 60×50×2×25mm.

[0053] S4: Insert the iron core from S2 into the mold in S3 to achieve interference fit.

[0054] S5: Place the iron core and mold from S4 into a vacuum annealing furnace for vacuum crystallization annealing. The annealing process is 480℃ for 120 minutes + 550℃ for 120 minutes.

[0055] S6: Remove the annealed iron core from the mold.

[0056] S7: The annealed iron core is placed into a stainless steel protective box with dimensions of 61 / 49×51 / 39×0.8×25mm, and then sealed with 703 silicone rubber.

[0057] S8: The VA characteristics are measured using a core performance measuring instrument, and the initial permeability is calculated from the VA data.

[0058] When the input current is 18mA, the corresponding applied magnetic field strength is 0.08A / m, and the output electromotive force V is 0.6mV. The calculated initial permeability is 183,000. Example

[0059] An elliptical nanocrystalline alloy iron core with dimensions of 80×60×20×20mm.

[0060] The specific plan is as follows:

[0061] S1: Calculate the required outer perimeter L1 of the elliptical iron core based on the major semi-axis dimension A1 and minor semi-axis dimension B1 of the elliptical toroidal iron core. L1 = 2πB1 + 4(A1 - B1) = 145.5 mm.

[0062] S2: A ring-shaped iron core with an outer circumference of 114.4 mm, a thickness of 20 mm, and a height of 20 mm is wound using an amorphous alloy strip with the composition of Fe73.5Si13.5B9Nb3Cu1.

[0063] S3: An elliptical ring-shaped mold is made from a Ti-34%Nb-0.1%O alloy plate with a negative expansion coefficient of -3.0×10-5, a thickness of 4mm, and a cold deformation of 95%. The dimensions of the elliptical ring are 80×60×4×25mm.

[0064] S4: Insert the iron core from S2 into the mold in S3 to achieve interference fit.

[0065] S5: Place the iron core and mold from S4 into a vacuum annealing furnace for vacuum crystallization annealing. The annealing process is 480℃ for 120 minutes + 550℃ for 120 minutes.

[0066] S6: Remove the annealed iron core from the mold.

[0067] S7: The annealed iron core is placed into a stainless steel protective box with dimensions of 82 / 60×62 / 40×1.0×25mm, and then sealed with 703 silicone rubber.

[0068] S8: The VA characteristics are measured using a core performance measuring instrument, and the initial permeability is calculated from the VA data.

[0069] When the input current is 22mA, the corresponding applied magnetic field strength is 0.08A / m, and the output electromotive force V is 1.1mV. The calculated initial permeability is 167,000.

[0070] The advantages of this invention are: by pre-deformation before annealing and mold shrinkage during annealing, the deformation during crystallization is offset, the internal stress is greatly reduced, and a high initial magnetic permeability is obtained; it can achieve uniform deformation of the elliptical ring core, so that the elliptical ring shape is maintained after annealing; the mold is simple and the production efficiency is high.

[0071] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A process for preparing an elliptical ring-shaped nanocrystalline alloy core with high initial magnetic permeability, characterized in that, The specific steps include: S1, designing the elliptical toroidal iron core to be prepared and its mold; S2. Based on the dimensions and quantity of the elliptical annular iron core to be prepared, the amorphous alloy strip is wound into a circular annular iron core; wherein, the outer circumference of the elliptical annular iron core to be prepared is L1, and the outer circumference of the circular annular iron core is L2; ​​wherein L2 = L1 (1 + 1~2%); S3. The circular annular iron core is placed in a mold; the mold is made of TiNbO with a negative coefficient of thermal expansion, and the circular annular iron core is inserted into the mold by interference fitting; S4. The mold containing the circular annular iron core is placed in a vacuum annealing furnace for vacuum crystallization annealing; S5. After annealing, the annealed circular annular iron core is removed from the mold, placed into an elliptical annular stainless steel protective box, and encapsulated with silicone rubber; S6: The VA characteristics are measured using a core performance measuring instrument, and the initial permeability is calculated from the VA data.

2. The preparation process of the elliptical ring-shaped nanocrystalline alloy core with high initial permeability according to claim 1, characterized in that, The negative expansion coefficient of the TiNbO is -3.0 to -2.5 × 10⁻⁵.

3. The preparation process of the elliptical ring-shaped nanocrystalline alloy core with high initial permeability according to claim 1, characterized in that, The inner circumference of the mold is equal to the outer circumference of the designed iron core.

4. The preparation process of the elliptical ring-shaped nanocrystalline alloy core with high initial permeability according to claim 1, characterized in that, The vacuum crystallization annealing process involves raising the temperature to 480°C and holding it for 120 minutes, then raising the temperature to 550°C and holding it for another 120 minutes.

5. The preparation process of the elliptical ring-shaped nanocrystalline alloy core with high initial permeability according to claim 1, characterized in that, The inner circumference of the stainless steel protective box is equal to the outer circumference of the designed iron core.

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