Density consistency forming method for iron-nickel special-shaped magnetic powder core

Abstract

The invention discloses an iron-nickel special-shaped magnetic powder core density consistency forming method which comprises the following steps: step 1, determining the structure of an iron-nickel special-shaped magnetic powder core to be prepared and selecting a corresponding mold; then, the mold is divided into a plurality of small area units according to structural distribution and corresponding functions of the iron-nickel special-shaped magnetic powder core to be prepared; 2, each small area unit in the mold is filled with the corresponding preset amount of coated iron-nickel powder through a preset feeding box; 3, the filling powder is subjected to multi-stage compression molding; and step 4, carrying out heat treatment, impregnation and drying treatment on a semi-finished product subjected to compression molding to obtain the target iron-nickel special-shaped magnetic powder core. The invention aims to realize the consistency of the forming density of the iron-nickel special-shaped magnetic powder core.

Description

Technical Field

[0001] The invention relates to the technical field of iron-nickel special-shaped magnetic powder cores, and in particular to a density consistency molding method for iron-nickel special-shaped magnetic powder cores. Background Art

[0002] Magnetic powder core is a kind of soft magnetic material made by mixing ferromagnetic powder and insulating medium. The magnetic and electrical properties of magnetic powder core mainly depend on the magnetic permeability of powder material, the size and shape of powder, their filling factor, the content of insulating medium, molding pressure and heat treatment process. Among them, magnetic powder includes Fe-Si, Fe-Ni, Fe-Si-Al metal powder and amorphous and nanocrystalline alloy powder. The insulating coating agent can be roughly divided into organic coating agent (epoxy resin, polyamide resin, silicone resin, polyvinyl alcohol, phenolic resin and polystyrene, etc.) and inorganic coating agent (mica, water glass, oxide layer, etc.). The pressing methods mainly include cold pressing, warm pressing, vacuum hot pressing, two-step pressing, mold wall lubrication pressing, etc. However, in the cold pressing molding process, there are problems such as uneven density, insufficient mechanical strength and mold wear in the structural molding of special-shaped magnetic powder cores.

[0003] The existing invention patent with the patent publication number CN114005669A discloses a manufacturing process for a special-shaped ferrite core, which is formed by stamping: selecting soft ferrite particle powder, using a vertical molding machine or a high-speed rotary molding machine, using a mold bidirectional stamping to prepare a process-designed sealed blank or a connected blank; sintering; cutting and grinding; ultrasonic cleaning; inspection. Although it overcomes the phenomenon that the conventional preparation method of special-shaped magnetic core components is prone to product deformation, the core preparation loss is high and the density difference in different areas of different special-shaped magnetic cores is not considered. Summary of the invention

[0004] The main purpose of the present invention is to provide a density consistency forming method for iron-nickel special-shaped magnetic powder cores, aiming to solve the technical problems that the existing special-shaped magnetic loss is large and the structural forming of the special-shaped magnetic powder cores cannot be overcome and the density is uneven.

[0005] To achieve the above object, the present invention provides a method for forming an iron-nickel special-shaped magnetic powder core with uniform density, the method comprising the following steps:

[0006] Step 1, determining the structure of the iron-nickel special-shaped magnetic powder core to be prepared and selecting a corresponding mold, and then dividing the mold into a plurality of small area units according to the structural distribution of the iron-nickel special-shaped magnetic powder core to be prepared and its corresponding function;

[0007] Step 2, each small area unit in the mold is filled with a corresponding preset amount of coated iron-nickel powder using a preset feeding box;

[0008] Step 3, performing multi-stage pressing and molding on the filling powder;

[0009] Step 4, subjecting the semi-finished product after pressing to heat treatment-impregnation-drying treatment to obtain the target iron-nickel special-shaped magnetic powder core.

[0010] Optionally, the iron-nickel special-shaped magnetic powder core is an EE type magnetic powder core or an EQ type magnetic powder core, and after step 1 and before step 2, the process also includes pre-stirring at least three iron-nickel powders of different particle sizes according to a preset ratio, and the iron-nickel mass ratio in the iron-nickel powder of each particle size is 55:45.

[0011] Optionally, -500 mesh, -300 mesh, and -150 mesh iron-nickel powders are stirred and mixed in a mass ratio of 65%-75%, 20%-25%, and 5%-15%, respectively.

[0012] Optionally, in step 1, the mold of the iron-nickel special-shaped magnetic powder core is divided into a column area and an outer frame area, the column area includes two side column areas located at both ends and a middle column area located in the middle, and the outer frame area includes a middle column extension area, two side column extension areas and two middle column-side column extension connection areas.

[0013] Optionally, in step 2, the feeding box includes a box body, a feeding port located on the upper surface of the box body, and an open bottom surface of the box body, and a screen is centrally arranged on the bottom surface of the box body.

[0014] Optionally, the width of the screen is consistent with the width of the center column area.

[0015] Optionally, in step 3, a three-stage cylinder, a two-stage cylinder, and a one-stage cylinder are used to compact the filling powder in stages from the outer frame area to the column area.

[0016] Optionally, in step 4, the compression ratios of the two side column extension zones, the two middle column-side column extension connection zones and the two side column zones in the press-formed product are 2-2.1, and the compression ratio of the middle column zone and the middle column extension zone is 2.2-2.3.

[0017] Optionally, the step 3 specifically includes:

[0018] A three-stage cylinder is used to apply 5t of pressure to the filling powder in advance to preliminarily compact the powder;

[0019] Then, a secondary cylinder is used to apply 12 tons of pressure to the initially compacted filling powder to further compact the powder;

[0020] Finally, the first cylinder applies 19.5t of pressure on the filling powder compacted by the second cylinder to achieve the expected density and strength.

[0021] Optionally, step 4 specifically includes: sending the pressed semi-finished product into a preheating furnace and baking it in an atmosphere of 220°C for 3.5 hours, then transferring it to an atmosphere of 750°C for heat treatment for 2 hours, and after the product returns to room temperature, immersing it in an impregnation liquid pool with a concentration of 1.45±0.02 for 15 minutes, and finally drying it at 190°C for 2 hours to obtain the target iron-nickel special-shaped magnetic powder core.

[0022] Beneficial effects:

[0023] The present invention determines the structure of the iron-nickel shaped magnetic powder core to be prepared and selects the corresponding mold, and then divides the mold into multiple small area units according to the structural distribution of the iron-nickel shaped magnetic powder core to be prepared and its corresponding function; and each small area unit in the mold is filled with a corresponding preset amount of coated iron-nickel powder using a preset feeding box; then the filled powder is subjected to multi-stage compression molding; finally, the semi-finished product after compression molding is subjected to heat treatment-impregnation-drying treatment to obtain the target iron-nickel shaped magnetic powder core, wherein the iron-nickel mixed powder is added to the corresponding area in the mold by using a feeding box with a screen, and the screen is aligned with the width of the middle column area, so that the amount of iron-nickel mixed powder added in the middle column area and the middle column extension area is distinguished from that in other areas, and finally, different areas in the same mold are filled with iron-nickel mixed powders with different filling flow rates at the same time, so that the density of each area of ​​the iron-nickel shaped magnetic powder core is basically consistent after subsequent compression molding, so that the mechanical strength and magnetic properties caused by the density gradient can be avoided to be inconsistent, and the material cracking or defects can be avoided. In addition, the entire preparation process is simple and convenient, and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0025] Figure 1 It is a flowchart of an embodiment of a method for forming a uniform density iron-nickel special-shaped magnetic powder core according to the present invention;

[0026] Figure 2 for Figure 1 The structural diagram of the EE type magnetic powder core mold;

[0027] Figure 3 for Figure 1 The structural diagram of the EQ type magnetic powder core mold;

[0028] Figure 4 for Figure 1 A schematic diagram of the structure of the charging box used in the invention;

[0029] Figure 5 for Figure 2 Schematic diagram of the bottom structure in;

[0030] Figure 6 for Figure 1 A schematic diagram of the structure of the pressing operation in FIG.

[0031] Figure 7 To adopt Figure 1 The top view and cross-sectional view of the EE type magnetic powder core prepared by the method;

[0032] Figure 8 To adopt Figure 1 Top view and cross-sectional view of the EQ type magnetic powder core prepared by the method.

[0033] Description of Figure Numbers:

[0034] Label name Label name 1 First side column area 2 Middle column area 3 Second side column area 5 Feeding port 6 Bottom of box 7 Screen 101 First side column extension area 201 The first middle column-side column extension connection area 202 Center column extension area 203 The second middle column-side column extension connection area 301 Second side column extension area 21 First cylinder 22 Secondary cylinder 23 Three-stage cylinder 24 Undershoot 25 Base 26 Center cylinder 27 Female mold

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0039] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0040] See also Figure 1 The present invention provides a process of an embodiment of a method for forming a density consistency of an iron-nickel special-shaped magnetic powder core, the method comprising the following steps:

[0041] Step 1: determine the structure of the iron-nickel special-shaped magnetic powder core to be prepared and select a corresponding mold, and then divide the mold into multiple small area units according to the structural distribution of the iron-nickel special-shaped magnetic powder core to be prepared and its corresponding function.

[0042] Step 2: Fill each small area unit in the mold with a preset amount of coated iron-nickel powder using a preset feeding box.

[0043] Specifically, in this embodiment, the iron-nickel special-shaped magnetic powder core is an EE type magnetic powder core or an EQ type magnetic powder core. Figure 2-3 As shown, the iron-nickel special-shaped magnetic powder core mold is divided into a column area and an outer frame area, the column area includes the first and second side column areas 1, 3 located at both ends and the middle column area 2 located in the middle, and the outer frame area includes the middle column extension area 202, the first and second side column extension areas 101, 301 and the first and second middle column-side column extension connection areas 201, 203. And when the mold is actually filled, for the EE type magnetic powder core and the EQ type magnetic powder core, the material is filled from the outer frame area to the column area, and the overall width of the middle column area 2 is greater than the width of the two side column areas, and the structure and size of the two side column areas are basically the same, and then the width of the first and second side column extension areas 101, 301 is also smaller than the width of the corresponding middle column extension area 202, and the iron-nickel special-shaped magnetic powder core finally obtained also corresponds to the corresponding mold.

[0044] At the same time, before the magnetic powder core is pressed, at least three iron-nickel powders of different particle sizes are stirred in advance according to a preset ratio, and the iron-nickel mass ratio in the iron-nickel powder of each particle size is 55:45. And -500 mesh, -300 mesh, -150 mesh iron-nickel powders are stirred and mixed according to a mass ratio of 65%-75%, 20%-25%, 5%-15%, respectively. Preferably, for EE type magnetic powder cores, -500 mesh, -300 mesh, -150 mesh iron-nickel powders are stirred and mixed according to a mass ratio of 70%-75%, 20%-25%, 10%-15%, respectively. For EQ type magnetic powder cores, -500 mesh, -300 mesh, -150 mesh iron-nickel powders are stirred and mixed according to a mass ratio of 65%-70%, 20%-25%, 5%-15%, respectively. More preferably, the iron-nickel powder is stirred in a mixing barrel according to the proportion for 30 minutes to ensure its uniformity, and then the prepared organic-inorganic coating agent is poured into it and fully reacted at 70°C for 2.5 hours; after the powder is dried, a preset amount of coated iron-nickel powder is added to the corresponding mold using a feeding box.

[0045] Furthermore, if Figure 4-5As shown, the feeding box includes a box body, a feeding port 5 located on the upper surface of the box body, and a bottom surface 6 of the box body in an open state, and a screen 7 is arranged in the center of the bottom surface 6 of the box body. Specifically, the particle size of the screen 7 is 150μm-250μm, preferably, for EE type magnetic powder core, the particle size of the screen 7 is 180μm-250μm, and for EQ type magnetic powder core, the screen particle size of the screen 7 is 150μm-200μm; more preferably, the width of the screen 7 is consistent with the width of the middle column area 2 in the corresponding mold. When actually feeding, the screen 7 in the feeding box is located directly above the middle column area 2, and the material passing through the screen 7 in the feeding box falls into the middle column area 2. The purpose is to reduce the filling flow rate of the iron-nickel mixed powder entering the middle column area 2 by using the screen 7, so as to distinguish the added amount of the coated iron-nickel powder in the middle column area 2 and the middle column extension area 201 from other areas in the same time.

[0046] Step 3, performing multi-stage pressing and molding on the filling powder.

[0047] Specifically, a pressing device is used to press the filling powder, such as Figure 6 As shown, the pressing device includes a base 25, a lower punch 24 placed on the base 25, and a first-stage cylinder 21, a second-stage cylinder 22, and a third-stage cylinder 23 located above the lower punch 24. The lower punch 24 is provided with an iron-nickel shaped magnetic powder core mold, and the iron-nickel shaped magnetic powder core mold includes a female mold 26, and the base 25 is also embedded with a central cylinder 27 corresponding to the size of the mold, and then the filling powder is compacted from the outer frame area to the column area in stages by the third-stage cylinder 23, the second-stage cylinder 22, and the first-stage cylinder 21. Taking the EE type magnetic powder core pressing as an example, the third-stage cylinder is used to apply 5t of pressure to the filling powder in advance to preliminarily compact the powder; then the second-stage cylinder is used to apply 12t of pressure to the filling powder after the preliminary compaction to further compact the powder; finally, the first-stage cylinder is used to apply 19.5t of pressure to the filling powder after the compaction of the second-stage cylinder to achieve the expected density and strength.

[0048] Step 4, subjecting the semi-finished product after pressing to heat treatment-impregnation-drying treatment to obtain the target iron-nickel special-shaped magnetic powder core.

[0049] Specifically, when the EE type magnetic powder core is pressed, the semi-finished product after pressing is sent to a preheating furnace and baked in a 220°C atmosphere for 3.5 hours, then transferred to a 750°C atmosphere for heat treatment for 2 hours, and when the product returns to room temperature, it is immersed in an impregnation liquid pool with a concentration of 1.45±0.02 for 15 minutes, and finally dried at 190°C for 2 hours to obtain the target iron-nickel special-shaped magnetic powder core. And the compression ratios of the first and second side column extension areas 101, 301, the first and second middle column-side column extension connection areas 201, 203 and the first and second side column areas 1, 3 in the semi-finished product after pressing are all 2-2.1, and the compression ratios of the middle column area 2 and the middle column extension area 202 are 2.2-2.3. Preferably, the compression ratios of the two side column extension areas, the two middle column-side column extension connection areas and the two side column areas in the semi-finished product after pressing are 2.1, and the compression ratios of the middle column area and the middle column extension area are 2.2. The compression ratio of each partition is set based on the initial density and theoretical density of the iron-nickel powder to set a preliminary compression ratio range, and then the initial compression ratio is calculated based on the target density and initial powder density of each area. It can be calculated using the following formula:

[0050]

[0051] Where: C is the compression ratio, ρ f is the target density, ρ0 is the initial powder density, and after calculating the preliminary compression ratio, finite element analysis (FEA) is used to simulate the pressure distribution and density changes during the pressing process to predict the molding effect of each area. Based on the simulation results, the compression ratio of each area is fine-tuned to optimize density uniformity and reduce stress concentration.

[0052] Furthermore, if Figure 7 The EE type magnetic powder core prepared by the above method is shown in Table 1, and the corresponding size range and parameters are shown in Table 1.

[0053] Table 1 Size range and parameters of each area of ​​EE type magnetic powder core

[0054]

[0055] The width F of the middle column area 2 in the EE type magnetic powder core prepared above is greater than the width L corresponding to the first and second side column areas 1 and 3, and the outer frame density ρ1 is not much different from the column density ρ2.

[0056] As well as Figure 8 The EQ type magnetic powder core prepared by the above method is shown in Table 2, and the corresponding size range is shown in Table 2.

[0057] Table 2 Dimensions and parameters of each area of ​​EQ type magnetic powder core

[0058]

[0059] The width D of the middle column area 2 in the EQ type magnetic powder core prepared above is greater than the widths (AE, AG) of the first and second side column areas 1 and 3, and the outer frame density ρ1 is not much different from the column density ρ2.

[0060] Furthermore, in order to better illustrate the effect of the product prepared by the present invention, the EE type magnetic powder core produced by the prior art is used as a comparative example to compare the performance of the product prepared by the present invention, and the details are shown in Table 2.

[0061] Table 3 Performance comparison of EE / EQ type magnetic powder cores obtained by the embodiment and prior art

[0062]

[0063] It can be seen from Table 3 that the density difference between the column area and the outer frame area in the EE / EQ type magnetic powder core prepared by the present invention is smaller than that in the comparative example, and thus the preparation method in the present invention can effectively improve the density uniformity of the finished product, and when the comparative example and the EE / EQ type magnetic powder core in the present invention are used in corresponding devices, it is measured that the inductance value of the device applied with the EE / EQ type magnetic powder core of the present invention is greater than that of the comparative example, and the DC Bias value of the device applied with the EE / EQ type magnetic powder core of the present invention is greater than that of the comparative example, and the Core Loss value of the device applied with the EE / EQ type magnetic powder core of the present invention is less than that of the comparative example, and the yield of the prepared device is also much higher than that in the comparative example, and thus the magnetic powder core prepared by the present invention has improved molding rate, mechanical strength and geometric accuracy, and is suitable for the production of complex-shaped magnetic powder cores requiring high quality and high performance.

[0064] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for forming a uniform density iron-nickel special-shaped magnetic powder core, characterized in that: The method comprises the following steps: Step 1, determining the structure of the iron-nickel special-shaped magnetic powder core to be prepared and selecting a corresponding mold, and then dividing the mold into a plurality of small area units according to the structural distribution of the iron-nickel special-shaped magnetic powder core to be prepared and its corresponding function; Step 2, each small area unit in the mold is filled with a corresponding preset amount of coated iron-nickel powder using a preset feeding box; Step 3, performing multi-stage pressing and molding on the filling powder; Step 4, subjecting the semi-finished product after pressing to heat treatment-impregnation-drying treatment to obtain the target iron-nickel special-shaped magnetic powder core.

2. The density consistency forming method of the iron-nickel special-shaped magnetic powder core according to claim 1 is characterized in that: The iron-nickel special-shaped magnetic powder core is an EE type magnetic powder core or an EQ type magnetic powder core. After step 1 and before step 2, the method further comprises pre-stirring at least three iron-nickel powders of different particle sizes according to a preset ratio, and the iron-nickel mass ratio in the iron-nickel powder of each particle size is 55:

45.

3. The density consistency forming method of the iron-nickel special-shaped magnetic powder core according to claim 2 is characterized in that: The iron-nickel powders of -500 mesh, -300 mesh and -150 mesh are stirred and mixed in a mass ratio of 65%-75%, 20%-25% and 5%-15% respectively.

4. The density consistency forming method of the iron-nickel special-shaped magnetic powder core according to claim 2 is characterized in that: In step 1, the mold of the iron-nickel special-shaped magnetic powder core is divided into a column area and an outer frame area, the column area includes two side column areas located at both ends and a middle column area located in the middle, the outer frame area includes a middle column extension area, two side column extension areas and two middle column-side column extension connection areas, and the width of the middle column area is greater than the width of the two side column areas.

5. The density consistency forming method of the iron-nickel special-shaped magnetic powder core according to claim 4 is characterized in that: In step 2, the feeding box includes a box body, a feeding port located on the upper surface of the box body, and an open bottom surface of the box body, and a screen is arranged in the center of the bottom surface of the box body.

6. The density consistency forming method of the iron-nickel special-shaped magnetic powder core according to claim 5 is characterized in that: The width of the screen is consistent with the width of the center column area.

7. The density consistency forming method of the iron-nickel special-shaped magnetic powder core according to claim 4 is characterized in that: In step 3, a three-stage cylinder, a two-stage cylinder, and a one-stage cylinder are used to compact the filling powder in stages from the outer frame area to the column area.

8. The density consistency forming method of the iron-nickel special-shaped magnetic powder core according to claim 5, characterized in that: In step 4, the compression ratios of the two side column extension areas, the two middle column-side column extension connection areas and the two side column areas in the semi-finished product after press forming are 2-2.1, and the compression ratio of the middle column area and the middle column extension area is 2.2-2.

3.

9. The density consistency forming method of the iron-nickel special-shaped magnetic powder core according to claim 7, characterized in that: The step 3 specifically includes: A three-stage cylinder is used to apply 5t of pressure to the filling powder in advance to preliminarily compact the powder; Then, a secondary cylinder is used to apply 12 tons of pressure to the mold after the initial compaction to further compact the powder; Finally, the first cylinder applies 19.5t of pressure to the mold compacted by the second cylinder to achieve the expected density and strength.

10. The method for forming a uniform density iron-nickel special-shaped magnetic powder core according to any one of claims 1 to 9, characterized in that: The step 4 specifically includes: sending the pressed product into a preheating furnace and baking it in an atmosphere of 220°C for 3.5 hours, then transferring it to an atmosphere of 750°C for heat treatment for 2 hours, and after the product returns to room temperature, immersing it in an impregnation liquid pool with a concentration of 1.45±0.02 for 15 minutes, and finally drying it at 190°C for 2 hours to obtain the target iron-nickel special-shaped magnetic powder core.

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