Amorphous soft magnetic composite magnetic powder core densification pressing method and equipment

Abstract

The invention discloses an amorphous soft magnetic composite magnetic powder core densification pressing method and equipment. The method comprises the following steps that 1, granulated amorphous alloy powder is placed in a pressing mold; 2, a temperature control system is started, and the temperature of the mold is adjusted to be within a specified range; 3, an ultrasonic generator with a vibration control device is started; 4, under the adjustment of a pressure control system, the pressing mold applies pressure to the powder, and the yield stress of the amorphous alloy powder is reduced through ultrasonic vibration while pressing is conducted; through the implementation of the method, ultrasonic vibration is applied in the pressing process, the yield stress is effectively reduced, and the fluidity and plastic deformation capacity are enhanced, so that the compactness and surface quality of a formed part are effectively improved, and the method has certain use value and popularization value.

Description

Technical Field

[0001] The present invention relates to the technical fields of powder metallurgy and advanced material processing, and particularly to a method and equipment for densification pressing of amorphous soft magnetic composite powder cores. Background Art

[0002] Due to its unique disordered atomic arrangement structure, amorphous alloys not only exhibit characteristics such as high strength, high hardness, and corrosion resistance, but also show excellent magnetic properties, such as high saturation magnetic induction intensity, low coercivity, and low iron loss, and are widely used in fields such as electronic devices, power transformers, and high-efficiency motors. In soft magnetic applications, the high initial magnetic permeability and low high-frequency loss of amorphous alloys make them an ideal choice for energy-saving and efficient materials, and amorphous soft magnetic composite powder cores are a particularly important application field. In order to fully utilize their soft magnetic properties, the powder pressing and forming process of amorphous alloy powders needs to ensure the internal density and the integrity of the microstructure of the material to reduce the influence of pores and other defects on the magnetic properties.

[0003] However, in the traditional powder pressing and forming process, due to the characteristics of high surface hardness, high elastic modulus, high yield stress, and low plastic deformation ability of powder particles, the powder particles are difficult to flow and plastically deform sufficiently during the pressing process, resulting in poor density and uniformity of the formed parts, and greatly increasing the difficulty of pressing and forming. When the powder particles are compressed, they mainly undergo slight elastic deformation, and plastic deformation hardly exists, and problems such as insufficient deformation, internal defects, and poor surface quality are prone to occur in the traditional pressing and forming process. In the prior art, in order to improve the pressing and forming effect of amorphous alloys, methods such as increasing the pressing pressure or forming under high-temperature conditions are usually adopted, and various methods have been proposed to improve the pressing and forming effect of amorphous alloys.

[0004] Chinese Patent CN106205935A, an amorphous soft magnetic composite powder core and its preparation method, discloses a forming method using an increased pressing pressure, and the pressure is 20-25 tons per square centimeter. However, high pressure will introduce large internal stresses during the forming process, and the die life is short and the forming cost is high under high-pressure conditions.

[0005] Chinese Patent CN109036753A, an amorphous nanocrystalline composite powder core and its preparation method, discloses an amorphous nanocrystalline composite powder core and its preparation method, which is prepared by a spark plasma sintering process. This amorphous nanocrystalline composite powder core has a high density and low magnetic loss, but it needs to be heated to 450-600 degrees and sintered by spark plasma for 2-4 minutes. The preparation process is complex, the equipment requirements are high, and it is not suitable for large-scale production.

[0006] In summary, the prior art has the following deficiencies in the process of hot pressing amorphous alloys: First, the die life is short and the forming cost is high under high-pressure conditions; second, high-temperature forming easily leads to partial crystallization of the amorphous structure, affecting the comprehensive properties of the material. In addition, a large amount of internal stress is introduced during the pressing process under high forming pressure. Due to the crystallization temperature limitation of the 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 lower magnetic permeability and higher loss of the magnetic powder core, weakening the comprehensive properties of the amorphous alloy, and severely limiting its application in high-performance products. Therefore, there is an urgent need for a new forming method that can improve the density and performance of amorphous alloy products while reducing the forming pressure and simplifying the process. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention provides a method and equipment for densifying and pressing amorphous soft magnetic composite magnetic powder cores, aiming to solve the problems of complex preparation process, non-spherical or near-spherical alloy powder, and the need to improve the iron loss performance.

[0008] To achieve the above object, the present invention provides the following technical solutions: On the one hand, the present invention provides a method for densifying and pressing amorphous soft magnetic composite magnetic powder cores, including the following steps: Step 1: Place the granulated amorphous alloy powder in a pressing die. Step 2: Start the temperature control system and adjust the temperature of the die within a specified range. Step 3: After the upper die enters the cavity opening of the middle die, start the ultrasonic generator with a vibration control device. Step 4: Under the adjustment of the pressure control system, the pressing die applies pressure to the powder, and at the same time, uses ultrasonic vibration to reduce the yield stress of the amorphous alloy powder. Step 5: Maintain the synergistic effect of vibration and pressure until the amorphous soft magnetic composite magnetic powder core is densely formed. Finally, anneal the pressed amorphous soft magnetic composite magnetic powder core blank to form a high-density amorphous alloy product. By combining the ultrasonic vibration technology with the traditional pressing process, high-frequency vibration is applied during the forming process of the amorphous alloy powder to reduce its yield stress, improve its fluidity and plastic deformation ability, thereby achieving high-density forming.

[0009] Preferably, in Step 1, the sieved amorphous powder with a mesh size of 20 - 100 meshes is granulated and then placed in the pressing die.

[0010] Preferably, in Step 2, the temperature of the die is 20°C - 200°C.

[0011] Preferably, in Step 3, the ultrasonic generator applies vibration to the amorphous alloy powder at a frequency of 20 kHz - 40 kHz and an amplitude of 5 - 20 μm.

[0012] Preferably, in the steps 4 and 5, the pressure applied during the densification molding process of the amorphous soft magnetic composite powder core ranges from 100 MPa to 1200 MPa.

[0013] Preferably, in the step 5, the annealing temperature is 350°C to 500°C, and the annealing time is 0.5 h to 10 h.

[0014] Preferably, in the step 4, under the regulation of the pressure control system, the pressing die applies pressure to the amorphous alloy powder. The pressure control system includes a pressure sensor and a pressure feedback adjustment device. The pressure sensor is used to monitor the pressure during the pressing process in real time, and the pressure feedback adjustment device is used to adjust the pressure during the pressing process in real time.

[0015] Preferably, the material of the pressing die is an alloy, and the surface of the pressing die is treated with nitriding or coating for wear resistance.

[0016] Preferably, the vibration control device includes: a frequency adjustment module for adjusting the ultrasonic vibration frequency; an amplitude adjustment module for adjusting the ultrasonic vibration amplitude; a waveform control module for controlling the waveform characteristics of the ultrasonic wave.

[0017] On the other hand, the present invention provides a densification pressing device for an amorphous soft magnetic composite powder core, including a pressing die having an upper die, a lower die, and a middle die. A pressure control system and a temperature control system are provided on the pressing die. Ultrasonic generators are connected to both sides of the upper die and the lower die away from the middle die, and a filling port for adding amorphous alloy powder is provided on the middle die.

[0018] Substantive effects of the present invention: 1. In the present invention, by combining the ultrasonic vibration technology with the traditional pressing process, high-frequency vibration is applied during the molding process of the amorphous alloy powder, reducing its yield stress, significantly reducing the molding pressure, reducing model wear and equipment complexity, improving its fluidity and plastic deformation ability, and thus achieving high-density molding; 2. In the present invention, through ultrasonic vibration, the rearrangement and plastic deformation between particles are promoted, the density and microstructure uniformity of the molded product are significantly improved, and the problem of partial crystallization that may be caused by high-temperature molding is avoided, retaining the original characteristics of the amorphous alloy; 3. In the present invention, it is applicable to the processing of amorphous alloy products with complex geometric structures, especially having important engineering value in the fields of high-performance soft magnetic materials and functional materials, and having certain use value and promotion value. Description of the Drawings

[0019] Figure 1 It is a schematic flow diagram of Example 1.

[0020] Figure 2 It is a schematic structural diagram of the densification pressing equipment for the amorphous soft magnetic composite powder core of Example 4.

[0021] Figure 3 It is Figure 2 an enlarged schematic diagram of the structure of part A in Specific implementation manners

[0022] For the convenience of understanding the present invention, the present invention will be described in more detail below in conjunction with the accompanying drawings and specific implementation manners.

[0023] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific implementation manners and are not used to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or several related listed items.

[0024] Example 1:

[0025] Referring to Figure 1 shown, an amorphous soft magnetic composite powder core densification pressing method is used to press and form amorphous FeSiB powder to verify the actual effect of the present invention.

[0026] Commercial amorphous FeSiB powder is used, sieved through 500 meshes, with D50 being 10 μm. After granulation, it is sieved through 40 meshes. The mold material is selected as high-strength alloy steel, the surface of the mold is treated with nitriding for wear resistance, the temperature of the mold is 100 °C, the vibration frequency of the ultrasonic vibration device is 30 kHz, the amplitude is 10 μm, the pressing mold is a servo-controlled hydraulic press, and the maximum pressure is 1500 MPa.

[0027] The steps are as follows: Step 1: Powder filling, uniformly filling the granulated amorphous FeSiB sieved through 40 meshes into the mold cavity; Step 2: Adjust the temperature of the mold to 50 °C; Step 3: After the upper mold enters the cavity opening of the middle mold, start the upper and lower ultrasonic vibration modules, both with a vibration frequency of 30 kHz and an amplitude of 10 μm; Step 4: Pressing and forming, applying an axial pressure of 1200 MPa through the hydraulic press, and forming under the combined action of the axial pressure and ultrasonic vibration; Step 5: Demolding the magnetic powder core after forming: Stop the ultrasonic vibration after the pressure and vibration actions are completed, and demold; Step 6: The annealing temperature is 425°C and the annealing time is 5 h. The formed amorphous soft magnetic composite powder core is annealed to further reduce the residual internal stress and optimize the microstructure. Step 7: Subsequent inspection: Determine the yield rate of the formed parts, based on whether there are cracks and whether the deviation between the weight of the powder core and the designed weight is within ±1%.

[0028] As an implementation manner, in Step 4, under the regulation of the pressure control system, the pressing die applies pressure to the amorphous alloy powder. The pressure control system includes a pressure sensor and a pressure feedback regulation device. The pressure sensor is used to monitor the pressure during the pressing process in real time, and the pressure feedback regulation device is used to adjust the pressure during the pressing process in real time.

[0029] As an implementation manner, the vibration control device includes: A frequency adjustment module for adjusting the ultrasonic vibration frequency; An amplitude adjustment module for adjusting the ultrasonic vibration amplitude; A waveform control module for controlling the waveform characteristics of the ultrasonic wave.

[0030] Table 1: Comparison of the relative density and yield rate of the formed parts under different pressures with / without ultrasonic vibration assistance.

[0031]

[0032] Measure the density of the formed parts under the above conditions. The results show that the relative density of the formed parts is 83.91%, which is equivalent to the relative density of the formed parts by the traditional method without ultrasonic vibration at 2000 MPa, and is much higher than the relative density of 77.83% of the formed parts by the traditional method without ultrasonic vibration at 1200 MPa. Continuously form 100 samples. After inspection, 98 of the products have a smooth surface and no cracks, and the yield rate is 98%, which is significantly higher than the yield rate of 92% of the traditional method. Observed by scanning electron microscope (SEM), the internal pores of the formed parts are significantly reduced, the particles are tightly combined, and the microstructure has good uniformity.

[0033] The amorphous FeSiB powder products formed by the above method have significantly improved density and surface quality, and the process parameters are stable and the applicability is wide, providing important technical support for the large-scale production of amorphous alloy materials.

[0034] Example 2:

[0035] This example is basically the same as Example 1, except that this example provides a device for ultrasonic-assisted pressing and forming to process Fe 73.5 Si 13.5 B 9 Nb3 Cu 1 Scheme for compacting amorphous alloy powder into shape.

[0036] The specific structure of the compacting device includes a main compacting mechanism, an ultrasonic vibration device, a pressure control system and a temperature control system. Among them, SKD11 die steel is used to make the upper and lower dies, and the die surface is treated by plasma nitriding. The vibration working frequency of the ultrasonic vibration device is 30 kHz, and the adjustable range of the amplitude is 0 - 30 μm. A servo hydraulic system is adopted, and the maximum pressure can reach 1500 MPa. An oil cooling system is used to control the die temperature, with the temperature control range of 20 - 160 °C and the control accuracy of ±1 °C.

[0037] The specific operation steps are as follows: Step 1. Start the press and load the amorphous alloy powder with a particle size D 50 of 20 μm, which is granulated and passes through a 60 - mesh sieve, including Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 into the die; Step 2. Set the die temperature to 150 °C; Step 3. Set the parameters of the ultrasonic generator: the vibration frequency is 30 kHz, the amplitude is 20 μm, and the waveform is a sine wave; Step 4. Apply an axial pressure of 1000 MPa through the hydraulic press and form under the combined action of the axial pressure and ultrasonic vibration; Step 5. Demold the magnetic powder core after forming: Stop the ultrasonic vibration after the pressure and vibration actions are completed, and then demold; Step 6. Heat - treat the formed part at 450 °C for 2 hours; Step 7. Subsequent inspection: Determine the yield rate of the formed part, based on whether there are cracks and whether the deviation between the weight of the magnetic powder core and the designed weight is within ±1%.

[0038] Under the above conditions, the relative density of the formed part reaches 84.75%, which is 2.88% higher than that of the formed part under the same pressure of 1000 MPa by the traditional pressing method, and the yield rate is increased from the original 89% to 96%.

[0039] In this embodiment, through the method of ultrasonic vibration - assisted pressing, the density and yield rate of Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 amorphous alloy powder are significantly improved, providing a reliable technical solution for the industrial production of amorphous alloy functional parts.

[0040] Example 3:

[0041] This example is basically the same as Example 1, except that in this example, a method of using ultrasonic vibration to improve the density of amorphous alloy during pressing is adopted to press the FeSiBCCr amorphous alloy powder to verify the applicability and process effect of this method on different amorphous alloy materials.

[0042] Particle size D 50 The amorphous FeSiBCCr powder with a size of 15 μm has a composition of Fe 78 Si 11.5 B 6 C 1 Cr 3.5 (atomic percentage). The mold material is WC-Co cemented carbide, the mold cavity size is 12 mm in outer diameter, 7 mm in inner diameter, and 5 mm in depth. The mold surface is coated with a TiN coating to improve wear resistance and reduce the friction coefficient. The vibration frequency of the ultrasonic vibration device is set to 35 kHz, and the amplitude is 15 μm.

[0043] The specific implementation steps are as follows: Step 1. Powder filling: The FeSiBCCr amorphous alloy powder granulated and passed through an 80-mesh sieve is evenly filled into the mold; Step 2. Heat the mold to a temperature of 180 °C; Step 3. Set the vibration frequency to 35 kHz and the amplitude to 15 μm; Step 4. Use a hydraulic press to apply a pressure of 800 MPa and press it into shape under the combined action of the ultrasonic vibration device; Step 5. Stop the pressure loading and the vibration device, and demold the formed part; Step 6. The heat treatment method is annealing at 400 °C for 5 hours.

[0044] Step 7. Determine the yield rate of the formed part, based on whether there are cracks, and the deviation between the weight of the magnetic powder core and the designed weight is within ±1%.

[0045] The relative density of the formed body prepared under the above forming conditions reaches 79.16%, which is 5.19 percentage points higher than the relative density of 73.97% under the traditional pressing process at a pressure of 800 MPa. 100 samples are continuously pressed. After testing, the yield rate is 96%, which is significantly higher than the yield rate of the traditional process (about 89%).

[0046] Observed by scanning electron microscopy (SEM), it is found that the porosity inside the formed part is significantly reduced, the particle interface is well combined, and there are no cracks or delamination phenomena; the compressive strength of the formed part is tested and is about 15% higher than that of the formed part under the same pressure by the traditional method.

[0047] This embodiment shows that the method of the present invention is also applicable to the pressing forming of FeSiBCCr amorphous alloy powder. Through the synergistic action of ultrasonic vibration and pressure, the density, mechanical properties and yield rate of the formed parts are effectively improved, providing reliable technical support for the industrial production of high-performance amorphous magnetic materials.

[0048] Compared with the traditional pressing method, when using the device and method provided in the above embodiment, the green density of the compact can be increased by 2% - 10%, and the pressing pressure can be reduced by 20% - 50%.

[0049] Example 4:

[0050] Refer to Figure 2 、 Figure 3 This embodiment is basically the same as Embodiment 1, except that a densification pressing device for amorphous soft magnetic composite powder cores includes a pressing die 10 with an upper die 2, a lower die 6 and a middle die 5. A temperature control system 4 and a pressure control system 8 are provided on the pressing die 10. An upper ultrasonic generator 1 and a lower ultrasonic generator 7 are respectively connected to the sides of the upper die and the lower die far away from the middle die. A filling port 3 for adding amorphous alloy powder is provided on the middle die.

[0051] As an implementation manner, the temperature control system 4 is provided on the middle die 5, and the pressure control system 8 is provided at the upper and lower ends of the pressing die 10.

[0052] The usage steps of the densification pressing device for amorphous soft magnetic composite powder cores include: Step 1: Powder filling, uniformly filling the sieved amorphous FeSiB with 40 meshes after granulation into the die cavity; Step 2: Heating the die to make its temperature reach 80 °C; Step 3: Set the vibration frequency of both the upper and lower ultrasonic vibration modules to 30 kHz and the amplitude to 10 μm; Step 4: Pressing forming, applying an axial pressure of 1200 MPa through a hydraulic press to form under the combined action of the axial pressure and ultrasonic vibration; Step 5: Demolding the formed powder core after forming: Stop the ultrasonic vibration after the pressure and vibration actions are completed, and demold; Step 6: Heat-treat the formed part at 350 °C for 10 hours.

[0053] Step 7: Subsequent detection: Determine the yield rate of the formed part, based on whether there are cracks, and the deviation between the weight of the powder core and the designed weight is within ±1%.

[0054] The raw materials and equipment used in the present invention are all common raw materials and equipment in the field without special instructions; the methods used in the present invention are all conventional methods in the field without special instructions.

[0055] As described above, it is only a preferred embodiment of the present invention and does not impose any limitations on the present invention. Any simple modifications, changes, and equivalent transformations made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for densification and pressing of 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 within the specified range; Step 3: After the upper mold enters the cavity of the middle mold, start the 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 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 densifying and pressing an amorphous soft magnetic composite powder core according to claim 1, characterized in that: In the step 1, a 20-100 mesh sieved amorphous powder is selected and granulated and then placed in a pressing mold.

3. The method for densifying and pressing an amorphous soft magnetic composite powder core according to claim 1, characterized in that: In step 2, the temperature of the mold is 20°C-200°C.

4. The method for densifying and pressing an amorphous soft magnetic composite powder core according to claim 1, characterized in that: In step 3, the vibration frequency of the ultrasonic generator is 20kHz-40kHz, and the amplitude is 5-20μm.

5. The method for densification and pressing of an amorphous soft magnetic composite powder core according to claim 1, characterized in that: In step 4 and step 5, the pressure applied during the compacting process of the amorphous soft magnetic composite magnetic powder core is in the range of 100 MPa to 1200 MPa.

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

7. 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 adjust the pressure during the pressing process in real time.

8. The method for densification and pressing of an amorphous soft magnetic composite powder core according to claim 1, 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.

9. 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: A 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 ultrasonic wave.

10. An amorphous soft magnetic composite magnetic powder core densification pressing device, characterized in that: The invention comprises a pressing die having an upper die, a lower die and a middle die, wherein the pressing die is provided with a pressure control system and a temperature control system, an upper ultrasonic generator and a lower ultrasonic generator are respectively connected to the sides of the upper die and the lower die away from the middle die, and the middle die is provided with a filling port for adding amorphous alloy powder.

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