A densification pressing method and equipment for amorphous soft magnetic composite magnetic powder core

Abstract

The invention discloses a densification pressing method and equipment for an amorphous soft magnetic composite magnetic powder core. The method comprises the following steps: step 1: placing granulated amorphous alloy powder in a pressing mold; step 2: starting a temperature control system and adjusting the temperature of the mold to within a specified range; step 3: starting an ultrasonic generator with a vibration control device; step 4: under the regulation of the pressure control system, the pressing mold applies pressure to the powder, and simultaneously uses ultrasonic vibration to reduce the yield stress of the amorphous alloy powder during pressing. Through the implementation of the invention, ultrasonic vibration is applied during the pressing process, thereby effectively reducing its yield stress, enhancing its fluidity and plastic deformation ability, thereby effectively improving the density and surface quality of the molded part, and having certain use value and promotion value.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy and advanced material processing, and in particular to a method and equipment for densifying and pressing an amorphous soft magnetic composite magnetic powder core. Background Art

[0002] Due to their unique disordered atomic structure, amorphous alloys not only exhibit high strength, high hardness, and corrosion resistance, but also excellent magnetic properties such as high saturation magnetic induction, low coercivity, and low iron loss. They are widely used in electronic equipment, power transformers, and high-efficiency motors. In soft magnetic applications, the high initial magnetic permeability and low high-frequency losses of amorphous alloys make them ideal energy-efficient and efficient materials. Amorphous soft magnetic composite powder cores are a particularly important application area. To fully utilize their soft magnetic properties, the compacting process of amorphous alloy powders must ensure the internal density and microstructural integrity of the material to minimize the impact of pores and other defects on magnetic properties.

[0003] However, in the traditional powder pressing process, due to the high surface hardness, high elastic modulus, high yield stress, and low plastic deformation ability of the powder particles, it is difficult for the powder particles to fully flow and plastically deform during the pressing process, resulting in poor density and uniformity of the molded parts, which greatly increases the difficulty of pressing. When the powder particles are compressed, they mainly undergo slight elastic deformation, while plastic deformation is almost non-existent. In the traditional pressing process, problems such as insufficient deformation, internal defects and poor surface quality are prone to occur. In the prior art, in order to improve the pressing effect of amorphous alloys, the method of increasing the pressing pressure or forming under high temperature conditions is usually adopted. In order to improve the pressing effect of amorphous alloys, a variety of methods have been proposed.

[0004] Chinese patent CN106205935A, an amorphous soft magnetic composite powder core and its preparation method, discloses a molding method utilizing increased pressing pressure, typically 20-25 tons per square centimeter. However, high pressure introduces significant internal stress during the molding process, shortens mold life, and increases molding costs.

[0005] Chinese patent CN109036753A, "An Amorphous Nanocrystalline Composite Magnetic Powder Core and Its Preparation Method," discloses an amorphous nanocrystalline composite magnetic powder core and its preparation method, produced through a spark plasma sintering process. This amorphous nanocrystalline composite magnetic powder core exhibits high density and low magnetic loss, but requires heating to 450-600°C and spark plasma sintering for 2-4 minutes. This complex preparation process and high equipment requirements make it unsuitable for large-scale production.

[0006] In summary, the existing technology has the following deficiencies in the process of pressing and forming amorphous alloys: first, the mold life is short and the molding cost is high under high pressure conditions; second, high-temperature molding easily leads to partial crystallization of the amorphous structure, affecting the comprehensive performance of the material. In addition, high molding pressure introduces a large amount of internal stress during the pressing process. Due to the crystallization temperature limit of amorphous powder, the heat treatment temperature needs to be kept below the crystallization temperature, making it difficult to effectively eliminate these internal stresses, resulting in a low magnetic permeability and high loss of the magnetic powder core, which weakens the comprehensive performance of the amorphous alloy and seriously limits its application in high-performance products. Therefore, there is an urgent need for a new molding method that can improve the density and performance of amorphous alloy products while reducing the molding pressure and simplifying the process. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention provides a densification pressing method and equipment for an amorphous soft magnetic composite magnetic powder core, aiming to solve the problems of complex preparation process, alloy powder not being spherical or nearly spherical, and iron loss performance still needing to be improved.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] In one aspect, the present invention provides a method for densification and pressing of an amorphous soft magnetic composite magnetic powder core, comprising the following steps:

[0010] Step 1: placing the granulated amorphous alloy powder in a pressing mold;

[0011] Step 2: Start the temperature control system and adjust the temperature of the mold to within the specified range;

[0012] Step 3: After the upper mold enters the middle mold cavity, start the ultrasonic generator with a vibration control device;

[0013] Step 4: Under the regulation of the pressure control system, the pressing mold applies pressure to the powder, and ultrasonic vibration is used to reduce the yield stress of the amorphous alloy powder during pressing;

[0014] Step 5: Maintain the synergistic effect of vibration and pressure until the amorphous soft magnetic composite powder core is densely formed. Finally, the pressed amorphous soft magnetic composite powder core blank is annealed to form a high-density amorphous alloy product. By combining ultrasonic vibration technology with traditional pressing processes, high-frequency vibration is applied during the amorphous alloy powder forming process to reduce its yield stress, improve its fluidity and plastic deformation ability, and thus achieve high-density forming.

[0015] Preferably, in step 1, amorphous powder sieved with 20-100 mesh is granulated and then placed in a pressing mold.

[0016] Preferably, in step 2, the temperature of the mold is 20°C-200°C.

[0017] Preferably, in step 3, the ultrasonic generator applies vibration to the amorphous alloy powder at a frequency of 20 kHz to 40 kHz and an amplitude of 5 to 20 μm.

[0018] Preferably, in step 4 and step 5, the pressure applied during the compaction molding of the amorphous soft magnetic composite magnetic powder core is in the range of 100 MPa to 1200 MPa.

[0019] Preferably, in step 5, the annealing temperature is 350° C.-500° C., and the annealing time is 0.5 h-10 h.

[0020] Preferably, in step 4, the pressing mold applies pressure to the amorphous alloy powder under the regulation of the pressure control system, and the pressure control system includes a pressure sensor and a pressure feedback regulating device, the pressure sensor is used to monitor the pressure during the pressing process in real time, and the pressure feedback regulating device is used to adjust the pressure during the pressing process in real time.

[0021] Preferably, the material of the pressing die is an alloy, and the surface of the pressing die is subjected to nitriding or plating wear-resistant treatment.

[0022] Preferably, the vibration control device comprises:

[0023] Frequency adjustment module, used to adjust the ultrasonic vibration frequency;

[0024] Amplitude adjustment module, used to adjust the ultrasonic vibration amplitude;

[0025] The waveform control module is used to control the waveform characteristics of the ultrasound.

[0026] On the other hand, the present invention provides a densification pressing device for an amorphous soft magnetic composite magnetic powder core, comprising a pressing mold having an upper mold, a lower mold and a middle mold, the pressing mold being provided with a pressure control system and a temperature control system, the upper mold and the lower mold being connected to an ultrasonic generator on one side away from the middle mold, and the middle mold being provided with a filling port for adding amorphous alloy powder.

[0027] Substantial effects of the present invention:

[0028] 1. In the present invention, by combining ultrasonic vibration technology with traditional pressing technology, high-frequency vibration is applied during the molding process of amorphous alloy powder, thereby reducing its yield stress, significantly reducing molding pressure, reducing mold wear and equipment complexity, and improving its fluidity and plastic deformation ability, thereby achieving high-density molding;

[0029] 2. In the present invention, ultrasonic vibration is used to promote the rearrangement and plastic deformation between particles, which significantly improves the density and microstructural uniformity of the molded product, avoids the problem of partial crystallization that may be caused by high-temperature molding, and retains the original characteristics of the amorphous alloy;

[0030] 3. The present invention is suitable for processing amorphous alloy products with complex geometric structures, especially has important engineering value in the field of high-performance soft magnetic materials and functional materials, and has certain use value and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the process of Example 1.

[0032] Figure 2 This is a schematic structural diagram of the amorphous soft magnetic composite powder core densification pressing equipment of Example 4.

[0033] Figure 3 for Figure 2 Enlarged schematic diagram of the structure of part A in the middle. DETAILED DESCRIPTION

[0034] In order to facilitate understanding of the present invention, the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments.

[0035] Unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are intended solely to describe specific embodiments and are not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the related listed items.

[0036] Example 1:

[0037] Reference Figure 1 As shown in FIG, a densification pressing method of an amorphous soft magnetic composite powder core is used to press amorphous FeSiB powder to verify the practical effect of the present invention.

[0038] Commercial amorphous FeSiB powder is used, sieved through 500 mesh, with a D50 of 10μm. After granulation, it is sieved through 40 mesh. The mold material is high-strength alloy steel, and the mold surface is nitrided and wear-resistant. The mold temperature is 100℃, the vibration frequency of the ultrasonic vibration device is 30kHz, the amplitude is 10μm, and the pressing mold is a servo-controlled hydraulic press with a maximum pressure of 1500MPa.

[0039] Here are the steps:

[0040] Step 1: Powder filling: evenly fill the 40-mesh sieved amorphous FeSiB after granulation into the mold cavity;

[0041] Step 2: Adjust the temperature of the mold to 50°C;

[0042] Step 3: After the upper mold enters the middle mold cavity, start the upper and lower ultrasonic vibration modules, and set the vibration frequency to 30kHz and the amplitude to 10μm.

[0043] Step 4: Pressing and forming: applying an axial pressure of 1200 MPa through a hydraulic press, and forming under the combined action of axial pressure and ultrasonic vibration;

[0044] Step 5: Demolding the magnetic powder core after molding: After the pressure and vibration are completed, stop the ultrasonic vibration and demold;

[0045] Step 6: The annealing temperature is 425°C and the annealing time is 5 hours. The formed amorphous soft magnetic composite powder core is annealed to further reduce the residual internal stress and optimize the microstructure.

[0046] Step 7: Subsequent inspection: The yield rate of the molded parts is determined based on whether there are cracks and whether the deviation between the weight of the magnetic powder core and the design weight is within ±1%.

[0047] As an embodiment, in step 4, under the regulation of the pressure control system, the pressing mold applies pressure to the amorphous alloy powder. The pressure control system includes a pressure sensor and a pressure feedback regulating device. The pressure sensor is used to monitor the pressure during the pressing process in real time, and the pressure feedback regulating device is used to adjust the pressure during the pressing process in real time.

[0048] As an embodiment, the vibration control device includes:

[0049] Frequency adjustment module, used to adjust the ultrasonic vibration frequency;

[0050] Amplitude adjustment module, used to adjust the ultrasonic vibration amplitude;

[0051] The waveform control module is used to control the waveform characteristics of the ultrasound.

[0052] Table 1: Comparison of relative density and yield of molded parts at different pressures with and without ultrasonic vibration assistance.

[0053]

[0054] Density measurements of the molded parts under these conditions revealed a relative density of 83.91%, comparable to that of parts molded using the conventional method without ultrasonic vibration at 2000 MPa, and significantly higher than the 77.83% relative density of parts molded using the conventional method without ultrasonic vibration at 1200 MPa. 100 samples were continuously molded, and 98 of them were found to have smooth, crack-free surfaces, resulting in a yield rate of 98%, significantly higher than the 92% yield achieved using the conventional method. Scanning electron microscopy (SEM) observations revealed significantly reduced internal porosity, close bonding between particles, and excellent microstructural uniformity.

[0055] The amorphous FeSiB powder products pressed and molded by the above method have significantly improved density and surface quality, and the process parameters are stable and have wide applicability, providing important technical support for the large-scale production of amorphous alloy materials.

[0056] Example 2:

[0057] This embodiment is basically the same as embodiment 1, except that this embodiment provides a method for forming Fe by using an ultrasonic-assisted pressing device. 73.5 Si 13.5 Scheme for pressing and molding B9Nb3Cu1 amorphous alloy powder.

[0058] The press-forming device comprises a main pressing mechanism, an ultrasonic vibrator, a pressure control system, and a temperature control system. The upper and lower molds are constructed of SKD11 mold steel, and the mold surfaces are plasma nitrided. The ultrasonic vibrator operates at a frequency of 30 kHz, with an adjustable amplitude range of 0-30 μm. A servo-hydraulic system is employed, achieving a maximum pressure of 1500 MPa. An oil cooling system controls mold temperature within a range of 20-160°C, with an accuracy of ±1°C.

[0059] The specific steps are as follows:

[0060] Step 1. Start the press and adjust the particle size D 50 20μm, granulated and passed through a 60-mesh sieve. 73.5 Si 13.5 B9Nb3Cu1 amorphous alloy powder is loaded into the mold;

[0061] Step 2. Set the mold temperature to 150°C;

[0062] Step 3. Set the ultrasonic generator parameters: vibration frequency is 30 kHz, amplitude is 20 μm, and waveform is sine wave;

[0063] Step 4. Apply 1000 MPa axial pressure through a hydraulic press, and form the part under the combined action of axial pressure and ultrasonic vibration;

[0064] Step 5. Demolding the magnetic powder core after molding: After the pressure and vibration are completed, stop the ultrasonic vibration and demold;

[0065] Step 6. Heat treat the molded part at 450°C for 2 hours;

[0066] Step 7. Subsequent testing: The yield rate of the molded parts is determined based on the presence of cracks and whether the deviation between the weight of the magnetic powder core and the design weight is within ±1%.

[0067] Under the above conditions, the relative density of the molded parts reached 84.75%, which was 2.88% higher than the relative density of the molded parts produced by the traditional pressing method under the same pressure of 1000MPa, and the yield rate was increased from the original 89% to 96%.

[0068] This embodiment significantly improves the Fe 73.5 Si 13.5 The density and yield of B9Nb3Cu1 amorphous alloy powder provide a reliable technical solution for the industrial production of amorphous alloy functional parts.

[0069] Example 3:

[0070] This embodiment is basically the same as Example 1, except that this embodiment adopts a method of using ultrasonic vibration to improve the density of amorphous alloy pressing and molding, and press-moldes FeSiBCCr amorphous alloy powder to verify the applicability and process effect of this method on different amorphous alloy materials.

[0071] Particle size D 50 15μm amorphous FeSiBCCr powder, composed of Fe 78 Si 11.5 B6C1Cr 3.5 (atomic percentage). The mold was made of WC-Co carbide, with a cavity size of 12 mm outer diameter, 7 mm inner diameter, and 5 mm depth. The mold surface was coated with TiN to improve wear resistance and reduce friction. The ultrasonic vibration device was set to a frequency of 35 kHz and an amplitude of 15 μm.

[0072] The specific implementation steps are as follows:

[0073] Step 1. Powder filling: FeSiBCCr amorphous alloy powder that has passed through an 80-mesh sieve after granulation is evenly filled into a mold;

[0074] Step 2. Heat the mold to a temperature of 180°C;

[0075] Step 3. Set the vibration frequency to 35kHz and the amplitude to 15μm;

[0076] Step 4. Use a hydraulic press to apply a pressure of 800 MPa and press into shape under the action of an ultrasonic vibration device;

[0077] Step 5. Stop the pressure loading and vibration device and demould the molded part;

[0078] Step 6: annealing at 400°C for 5 hours.

[0079] Step 7. Determine the yield rate of the molded parts based on the presence of cracks and whether the weight of the magnetic powder core is within ±1% of the design weight.

[0080] The molded body produced using these forming conditions achieved a relative density of 79.16%, an increase of 5.19 percentage points compared to the 73.97% achieved with conventional pressing at 800 MPa. Testing of 100 consecutive pressed samples revealed a yield rate of 96%, significantly higher than the approximately 89% yield achieved with conventional pressing.

[0081] Scanning electron microscopy (SEM) observations revealed that the internal porosity of the molded parts was significantly reduced, the particle interfaces were well bonded, and there were no cracks or delamination. The compressive strength of the molded parts was tested and found to be approximately 15% higher than that of parts molded by traditional methods under the same pressure.

[0082] This example demonstrates that the method of the present invention is also applicable to the compaction of FeSiBCCr amorphous alloy powders. Through the synergistic effect of ultrasonic vibration and pressure, the density, mechanical properties, and yield of the formed parts are effectively improved, providing reliable technical support for the industrial production of high-performance amorphous magnetic materials.

[0083] Compared with the traditional pressing method, the device and method provided by the above embodiment can increase the density of the green compact by 2% to 10% and reduce the pressing pressure by 20% to 50%.

[0084] Example 4:

[0085] Reference Figure 2 、 Figure 3 This embodiment is basically the same as Example 1, except that it is a densification pressing device for an amorphous soft magnetic composite magnetic powder core, comprising a pressing die 10 having an upper die 2, a lower die 6 and a middle die 5, the pressing die 10 is provided with a temperature control system 4 and a pressure control system 8, the upper die and the lower die are respectively connected to an upper ultrasonic generator 1 and a lower ultrasonic generator 7 on the side away from the middle die, and the middle die is provided with a filling port 3 for adding amorphous alloy powder.

[0086] As an embodiment, the temperature control system 4 is provided on the middle mold 5 , and the pressure control system 8 is provided at the upper and lower ends of the pressing mold 10 .

[0087] The steps for using the amorphous soft magnetic composite powder core densification pressing equipment include:

[0088] Step 1: Powder filling: evenly fill the 40-mesh sieved amorphous FeSiB after granulation into the mold cavity;

[0089] Step 2: Heat the mold to a temperature of 80°C;

[0090] Step 3: Set the vibration frequency of the upper and lower ultrasonic vibration modules to 30kHz and the amplitude to 10μm;

[0091] Step 4: Pressing and forming: applying an axial pressure of 1200 MPa through a hydraulic press, and forming under the combined action of axial pressure and ultrasonic vibration;

[0092] Step 5: Demolding the magnetic powder core after molding: After the pressure and vibration are completed, stop the ultrasonic vibration and demold;

[0093] Step 6: Heat treat the molded part at 350°C for 10 hours.

[0094] Step 7: Subsequent inspection: The yield rate of the molded parts is determined based on the presence of cracks and the deviation of the weight of the magnetic powder core from the design weight is within ±1%.

[0095] Unless otherwise specified, the raw materials and equipment used in the present invention are commonly used in the art; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0096] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A densification pressing method for an amorphous soft magnetic composite powder core, characterized in that: The following steps are involved: Step 1: placing the granulated amorphous alloy powder in a pressing mold; Step 2: Start the temperature control system and adjust the temperature of the mold to 20℃-200℃; Step 3: After the upper mold enters the middle mold cavity, start the ultrasonic generator with a vibration control device. The vibration frequency of the ultrasonic generator is 20kHz-40kHz and the amplitude is 5-20μm. Step 4: Under the regulation of the pressure control system, the pressing die applies axial pressure to the powder in the range of 100MPa-1200MPa, and ultrasonic vibration is used to reduce the yield stress of the amorphous alloy powder during pressing; Step 5: Maintain the synergistic effect of vibration and pressure until the amorphous soft magnetic composite magnetic powder core is densely formed, and finally anneal the pressed amorphous soft magnetic composite magnetic powder core blank to form a high-density amorphous alloy product.

2. The method for densification and pressing of an amorphous soft magnetic composite powder core according to claim 1, characterized in that: In the step 1, amorphous powder sieved with 20-100 meshes is selected and granulated and then placed in a pressing mold.

3. The method for densification and pressing of an amorphous soft magnetic composite powder core according to claim 1, characterized in that: In step 5, the annealing temperature is 350° C.-500° C., and the annealing time is 0.5 h-10 h.

4. The method for densification and pressing of an amorphous soft magnetic composite powder core according to claim 1, characterized in that: In step 4, under the regulation of the pressure control system, the pressing mold applies pressure to the amorphous alloy powder. The pressure control system includes a pressure sensor and a pressure feedback regulating device. The pressure sensor is used to monitor the pressure during the pressing process in real time, and the pressure feedback regulating device is used to regulate the pressure during the pressing process in real time.

5. The method for densification and pressing of an amorphous soft magnetic composite powder core according to claim 4, characterized in that: The material of the pressing die is alloy, and the surface of the pressing die is subjected to nitriding or plating wear-resistant treatment.

6. The method for densification and pressing of an amorphous soft magnetic composite powder core according to claim 1, characterized in that: The vibration control device comprises: Frequency adjustment module, used to adjust the ultrasonic vibration frequency; Amplitude adjustment module, used to adjust the ultrasonic vibration amplitude; The waveform control module is used to control the waveform characteristics of the ultrasound.

7. An amorphous soft magnetic composite powder core densification pressing device, characterized in that: A method for densifying an amorphous soft magnetic composite magnetic powder core according to any one of claims 1 to 6 is provided, comprising a pressing die having an upper die, a lower die and a middle die, the pressing die being provided with a pressure control system and a temperature control system, the upper die and the lower die being connected to an upper ultrasonic generator and a lower ultrasonic generator on one side away from the middle die, respectively, and the middle die being provided with a filling port for adding amorphous alloy powder.

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