A pulsed magnetic field forming press and forming method

Abstract

This invention relates to the field of molding press technology, and more particularly to a pulsed magnetic field molding press and molding method. The equipment includes a pulsed electromagnet, molding components, and a pulse control circuit, etc. A high-intensity pulsed magnetic field is generated by capacitor discharge to achieve rapid orientation of magnetic powder. Compared with traditional DC magnetic field molding, this invention can significantly shorten the charging and demagnetizing time and improve pressing efficiency. The mold uses a combination of magnetic and non-magnetic materials to optimize the magnetic field distribution. Demagnetization is achieved through reverse pulses, avoiding the influence of residual magnetism. This invention is suitable for one-time molding of magnets with a single unit weight ≤300g, simplifying the process and improving production efficiency and product quality.

Description

Technical Field

[0001] This invention relates to the field of molding press technology, and in particular to a pulse magnetic field molding press and molding method. Background Technology

[0002] The application of magnetic field forming presses covers materials such as NdFeB, SmCo, and ferrites. They commonly use DC electromagnets with a DC magnetic field strength typically between 1.5-2T, corresponding to 150,000-250,000 ampere-turns and an inductance between 3-8 Henry. To reduce excitation power costs, the industry typically uses rectified 380V AC power directly to power the electromagnet. However, due to inductance limitations, even with full-voltage strong pulling, reaching the rated magnetic field takes 2 seconds. Releasing electromagnetic energy at the end of orientation takes 1-2 seconds, and demagnetization also requires time. This means that, excluding the pressing time itself, the time for magnetic field rise and release during orientation and demagnetization alone can reach 5-7 seconds, significantly impacting production efficiency. Currently, the pressing time per die for these DC magnetic field presses is 12-16 seconds. Including feeding and unloading time, the overall cycle time is 30-45 seconds, resulting in low production efficiency.

[0003] Neodymium iron boron (NdFeB), as the rare-earth permanent magnet material with the highest magnetic energy product and the widest application, is often produced in small products weighing 5-20g due to its strong magnetism. To improve pressing efficiency, the industry typically first presses large blocks weighing 500-1200g, then cuts them into 4-10 square strips after sintering, and further cuts these strips into smaller square pieces. To reduce the cutting steps, some companies have tried using a multi-piece production method, hoping to eliminate one cutting step without reducing efficiency. However, both constant-volume feeding and independent weighing quantitative feeding methods have problems with weight errors and uneven powder distribution in individual pieces. Since the pressing height of a multi-piece press is the same, uneven weight distribution directly leads to differences in the density of the formed products, thus increasing the possibility of internal cracking during high-density forming. Therefore, most companies in the industry currently use a process of low-density forming followed by secondary isostatic pressing; especially when forming large blocks, the difference in internal and external density is greater, making the need for secondary isostatic pressing even more urgent.

[0004] The magnetic field strength of DC magnetic field presses is generally between 1.3 and 2.1 T, mainly limited by the size, energy consumption, and cost of the electromagnet. If the magnetic field strength could be increased to over 3 T, the remanence of the product would be further improved. However, increasing the magnetic field strength to over 3.0 T using DC methods requires extremely high costs, while pulsed magnetic fields can easily achieve higher magnetic field strengths. Furthermore, eliminating the secondary isostatic pressing process and reducing the cutting and breaking of materials are also pressing issues for the NdFeB industry. With the rapid increase in industry output, the low production efficiency of existing DC magnetic field presses has become increasingly prominent, making it difficult to meet the demands of large-scale production. Therefore, how to improve the production efficiency of magnetic field presses, eliminate the secondary isostatic pressing process, and reduce production costs are urgent problems that need to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a pulse magnetic field forming press, including a support platform, an upper beam, a lower beam, a nut, a guide column, a feeder, a sealed chamber, and a forming assembly. The lower beam is fixedly connected to the support platform, and the upper beam is positioned directly above the lower beam. A guide column is installed between the upper and lower beams via a nut. A sealed chamber is installed between the upper and lower beams. The forming assembly is located inside one side of the sealed chamber, and a feeder is installed on the other side of the sealed chamber. The press also includes a pallet, a mold frame, a pulse control circuit, and a pulse electromagnet. The pallet is connected to the lower beam via the mold frame, and a pulse electromagnet is mounted on the pallet. The pulse electromagnet is controlled by the pulse control circuit. The pulse electromagnet is a horizontal U-shaped structure, comprising a pulse orientation coil and an iron core. The pulse orientation coil is wound from a hollow copper tube covered with an insulating layer, and cooling water flows through the hollow copper tube. The two ends of the pulse orientation coil are externally connected to… The system includes a circulating pump for circulating cooling water. The iron core is composed of mutually insulated magnetic sheets with a thickness of 0.1-5mm. The pulse control circuit includes a power switch, an AC ammeter, a voltmeter, a constant power regulator, a step-up transformer, a rectifier circuit, a magnetizing circuit, and a demagnetizing circuit. The rectifier circuit includes high-voltage rectifier diodes D1-D4. The magnetizing circuit includes 2-5 sets of magnetizing alignment capacitors and alignment thyristors. Each set of magnetizing alignment capacitors is connected in series with an isolation diode, and all magnetizing alignment capacitors are connected in parallel with isolation diodes. The demagnetizing circuit includes a demagnetizing capacitor, a demagnetizing bidirectional thyristor, and a pulse alignment coil. The demagnetizing bidirectional thyristor is connected in series with the pulse alignment coil and then in parallel with the demagnetizing capacitor. The system also includes a freewheeling diode, which is connected in parallel with the pulse alignment coil and in series with the demagnetizing bidirectional thyristor.

[0006] Preferably, the forming component includes a mold, an upper telescopic cylinder, an upper die punch, a lower telescopic cylinder, and a lower die punch. The mold is located in the middle of the pallet, the upper telescopic cylinder is installed in the middle of the upper beam, and the upper die punch is detachably installed at the telescopic end of the upper telescopic cylinder. The lower telescopic cylinder is installed in the middle of the lower beam, and the lower die punch is detachably installed at the telescopic end of the lower telescopic cylinder. The upper die punch, the mold, and the lower die punch are aligned along the vertical axis.

[0007] Preferably, the core of the pulse electromagnet is made of alternating layers of silicon steel sheets or pure iron sheets with insulating varnish on the surface.

[0008] Preferably, the mold is composed of a magnetic plate and a non-magnetic block, and the resistivity of the mold is greater than 0.5 x 10⁻⁶. -6 Ω•m.

[0009] Preferably, the pulse width generated by the pulse magnetic field forming press is 5-20ms, the magnetic field strength is 1-5T, and the orientation pulse is applied 2-5 times.

[0010] Preferably, the upper telescopic cylinder and the lower telescopic cylinder are servo electric cylinders or hydraulic cylinders.

[0011] A pulsed magnetic field forming method, based on the aforementioned pulsed magnetic field forming press, includes the following steps:

[0012] S1. Spray release agent onto the inner wall of the mold cavity and the surfaces of the upper and lower die punches that come into contact with the powder. Add magnetic powder into the mold cavity and fill the sealed chamber with nitrogen until the oxygen content in the chamber is ≤200ppm and then stop filling.

[0013] S2. The upper die is inserted into the die cavity by controlling the upper telescopic cylinder to pre-compress the magnetic powder, and the pre-compressed density is 2.2-3.5 g / cm³. 3 ;

[0014] S3. Apply the first pulse magnetic field, then control the pressure ratio of the lower telescopic cylinder to the upper telescopic cylinder to be 1:(2-10) for floating pressing. Apply the next pulse every 0.1-0.5 seconds, and finally press until the density reaches 4.0-4.3 g / cm³. 3 Maintain pressure;

[0015] When S4 and K2 are turned on, the demagnetizing circuit works to perform demagnetization.

[0016] S5. Control the extension end of the lower telescopic cylinder to extend upward so that the lower die punch ejects the pressed product to achieve demolding.

[0017] Preferably, the demolding process employs variable pressure protection, with the upper telescopic cylinder pressure ranging from 800kg to 460kg during demolding. The execution of each process (S1-S5) is precisely and automatically controlled through PLC programming.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. The pulse magnetic field forming press of this invention has significant advantages in forming performance and pressing efficiency, and can adapt to the one-time forming requirements of small-sized products. Conventional DC electromagnets require 5-7 seconds for orientation, demagnetization, and magnetic field rise and release alone. This invention can shorten this charging and demagnetizing time, increasing pressing efficiency by 2-3 times. For products weighing less than 300g, the equipment uses multiple pulses instead of a DC magnetic field to complete orientation, and achieves demagnetization through a resonant structure composed of a capacitor and a coil. This saves 5-7 seconds of magnetic field forming time, enables one-time forming of small-sized products, simplifies the production process, and thus improves production efficiency.

[0020] 2. This invention overcomes the technical bottlenecks and traditional misconceptions in the application of pulsed magnetic fields. Eddy currents can partially cancel out the magnetic field, which is a key issue limiting the strength of pulsed magnetic fields. The device solves this problem through material innovation: the core uses high-permeability silicon steel sheets or pure patches with mutual insulation, and the mold uses composite materials with high resistivity and high permeability, ultimately outputting a strong magnetic field of over 5T. Traditional understanding holds that "the magnetic field must be maintained throughout the pressing process, otherwise the orientation of the magnetic powder will be destroyed." However, this invention has verified that, as a permanent magnet material, after the first pulsed magnetic field magnetization, if the magnetic circuit is designed as a closed structure, the magnetic powder can maintain consistent orientation by its own magnetism, eliminating the need to maintain the magnetic field throughout the process. This significantly reduces the complexity and energy consumption of the magnetic field control system. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the pulse magnetic field forming press of the present invention.

[0022] Figure 2 This is a cross-sectional view of the pulse magnetic field forming press of the present invention.

[0023] Figure 3 This is a cross-sectional view of the product after it has been pressed and ejected by the telescopic cylinder of the present invention.

[0024] Figure 4 This is a side view of the pulse magnetic field forming press of the present invention.

[0025] Figure 5 This is a top view of the pulse magnetic field forming press of the present invention.

[0026] Figure 6 This is a top view of the coil and core components of the present invention.

[0027] Figure 7 This is a side view of the coil and core components of the present invention.

[0028] Figure 8 This is a front view of the coil and core components of the present invention.

[0029] Figure 9 This is a schematic diagram of the pulse control circuit of the present invention.

[0030] In the attached diagrams: 1. Upper telescopic cylinder, 2. Upper beam, 3. Support platform, 4. Guide column, 5. Pulse orientation coil, 6. Iron core, 7. Support plate, 8. Mold frame, 9. Magnetic plate, 10. Lower beam, 11. Nut, 12. Lower telescopic cylinder, 13. Upper die punch, 14. Pressed product, 15. Mold, 16. Lower die punch, 17. Non-magnetic block, 18. Feeder, 19. Sealed chamber, J1. Power switch, A. AC ammeter, V. Voltmeter, H. Constant power regulator, B. Step-up transformer, D1-D4. High-voltage rectifier diodes, D5-D6. Isolation diodes, C. Orientation capacitor, C2. Demagnetizing capacitor, K1. Orientation thyristor, K2. Demagnetizing bidirectional thyristor, K3. Freewheeling diode. Detailed Implementation

[0031] like Figures 1-8 As shown, a pulse magnetic field forming press includes a support platform 3, an upper beam 2, a lower beam 10, a nut 11, a guide post 4, a feeder 18, a sealed chamber 19, and a forming assembly. The lower beam 10 is fixedly connected to the support platform 3. The upper beam 2 is positioned directly above the lower beam 10. A guide post 4 is installed between the upper beam 2 and the lower beam 10 via the nut 11. A sealed chamber 19 is installed between the upper beam 2 and the lower beam 10. The forming assembly is located inside one side of the sealed chamber 19. The feeder 18 is installed on the other side of the sealed chamber 19. The feeder 18 adopts existing technology and also includes a support plate 7, a mold frame 8, a pulse control circuit, and a pulse electromagnet. A support plate 7 is connected to the lower beam 10 via the mold frame 8. A pulse electromagnet is installed on plate 7 and support plate 7. The pulse electromagnet is controlled by a pulse control circuit. The pulse electromagnet is horizontal U-shaped and includes a pulse orientation coil 5 and an iron core 6. The pulse orientation coil 5 is made of hollow copper tube with an insulating layer. Cooling water flows through the hollow copper tube. The two ends of the pulse orientation coil 5 are connected to a circulating pump to circulate the cooling water. The iron core 6 is composed of mutually insulated magnetic sheets with a thickness of 0.1-5mm. Specifically, the iron core 6 is a structure of alternating layers of silicon steel sheets or pure iron sheets with insulating varnish on the surface. The insulating varnish between the silicon steel sheets or pure iron sheets can effectively suppress eddy current loss by interrupting the eddy current path, increasing resistance, and effectively thinning the magnetic layer.

[0032] The forming components include a mold 15, an upper telescopic cylinder 1, an upper die punch 13, a lower telescopic cylinder 12, and a lower die punch 16. The mold 15 is located in the middle of the support plate 7. The mold 15 is composed of a magnetic plate 9 and a non-magnetic block 17. The specific material can be ceramic or zirconium oxide. The resistivity of the mold 15 is greater than 0.5 x 10⁻⁶. -6Ω•m; An upper telescopic cylinder 1 is installed in the middle of the upper beam 2. An upper die punch 13 is detachably installed at the telescopic end of the upper telescopic cylinder 1. A lower telescopic cylinder 12 is installed in the middle of the lower beam 10. The upper telescopic cylinder 1 and the lower telescopic cylinder 12 are servo electric cylinders. A lower die punch 16 is detachably installed at the telescopic end of the lower telescopic cylinder 12. The upper die punch 13, the die 15 and the lower die punch 16 are aligned along the vertical axis.

[0033] like Figure 9 As shown, the pulse control circuit includes a power switch J1, an AC ammeter A, a voltmeter V, a constant power regulator H, a step-up transformer B, a rectifier circuit, a magnetization circuit, and a demagnetizing circuit. The rectifier circuit includes high-voltage rectifier diodes D1-D4. The magnetization circuit includes 2-5 sets of magnetizing alignment capacitors C and alignment thyristors K1. Each set of magnetizing alignment capacitors C is connected in series with an isolation diode D5, and each set of magnetizing alignment capacitors C is connected in parallel with an isolation diode D6. The demagnetizing circuit includes a demagnetizing capacitor C2, a demagnetizing bidirectional thyristor K2, and a pulse alignment coil 5. The demagnetizing bidirectional thyristor K2 is connected in series with the pulse alignment coil 5 and then in parallel with the demagnetizing capacitor C2. It also includes a freewheeling diode K3, which is connected in parallel with the pulse alignment coil 5 and in series with the demagnetizing bidirectional thyristor K2. During magnetization, the magnetizing alignment capacitors C are charged simultaneously and discharged separately. During demagnetization discharge, the demagnetization is achieved through the reduced resonance oscillation of the capacitors and the coil. It should be noted that the pulse width generated by the pulse magnetic field forming press is 5-20ms, the magnetic field strength is 1-5T, and the orientation pulse is applied 2-5 times.

[0034] A pulsed magnetic field forming method, based on the above-mentioned pulsed magnetic field forming press, includes the following steps:

[0035] S1. Spray release agent onto the inner wall of the mold cavity of mold 15 and the surfaces of the upper die punch 13 and lower die punch 16 that are in contact with magnetic powder. Add magnetic powder into the mold cavity of mold 15. Fill the sealed chamber 19 with nitrogen until the oxygen content in the chamber is ≤200ppm and then stop filling.

[0036] S2. The upper telescopic cylinder 1 controls the upper die punch 13 to insert into the die cavity to pre-compress the magnetic powder, and the pre-compressed density is 2.2-3.5 g / cm³. 3 ;

[0037] S3. Apply the first pulse magnetic field, then control the pressure ratio of the lower telescopic cylinder 12 to the upper telescopic cylinder 1 to be 1:(2-10) for floating suppression. Apply the next pulse every 0.1-0.5 seconds. During the process, each group of orientation thyristors K1 is turned on in turn to apply each pulse. Specifically, as follows... Figure 9As shown, from left to right, there are four pulse circuits. Each pulse circuit includes an orientation thyristor K1, an isolation diode D5, an isolation diode D6, a resistor R, an orientation capacitor C, and a pulse orientation coil 5. Each pulse circuit is activated by the corresponding K1 to apply the pulse, ultimately pressing to a density of 4.0-4.3 g / cm³. 3 Maintain pressure;

[0038] When S4 and K2 are turned on, the demagnetizing circuit works to perform demagnetization.

[0039] S5. Control the extension end of the lower telescopic cylinder 12 to extend upward so that the lower die punch 16 can push out the pressed product 14 to achieve demolding. Demolding adopts variable pressure protection. During the demolding process, the pressure of the upper telescopic cylinder 1 is 800kg-460kg. The execution of each process above S1-S5 is precisely and automatically controlled by PLC programming.

[0040] Example 1:

[0041] A pulsed magnetic field forming method, based on the above-mentioned pulsed magnetic field forming press, includes the following steps:

[0042] S1. Spray release agent onto the inner wall of the mold cavity of mold 15 and the surfaces of the upper and lower die punches 13 and 16 that come into contact with the magnetic powder. The agent is then fed into mold 15 (mold size 70x70x140 mm, mold resistivity 0.75×10⁻⁻⁻⁴) via feeder 18. 6 Add 284g of iron-boron magnetic powder with an average particle size of 3.5μm to the Ω•m mixture, and mix in 0.1% tributyl borate, 0.05% paraffin wax, 0.02% zinc stearate, and 0.1% petroleum ether, then smooth the powder surface. Fill the sealed chamber 19 with nitrogen until the oxygen content inside the chamber is less than 200ppm, then stop filling.

[0043] S2. The upper telescopic cylinder 1 controls the upper die punch 13 to insert into the die cavity to pre-compress the magnetic powder, pre-compressing it to densities of 2.0, 2.5, 3.0, 3.3, and 3.5 respectively; unit: g / cm³. 3 The pre-compression density is obtained by dividing the total weight of the magnetic powder by the volume of the magnetic powder in the mold cavity (the volume is the magnetic powder depth * the bottom area of ​​the mold cavity).

[0044] S3. Apply the first pulse magnetic field, then control the pressure ratio of the lower telescopic cylinder 12 to the upper telescopic cylinder 1 to be 1:(2-10) for floating pressing. Apply the next pulse every 0.1-0.5 seconds, and then press until the density is 4.0-4.3 g / cm³. 3 Maintain pressure;

[0045] When S4 and K2 are turned on, the demagnetizing circuit works to perform demagnetization.

[0046] S5. Control the telescopic end of the lower telescopic cylinder 12 to extend upward so that the lower die punch 16 can eject the pressed product 14 to achieve demolding. Specifically, the demolding process employs variable pressure protection. During demolding, the lower telescopic cylinder 12 maintains a constant pressure of 500 kg and a speed of 50 mm / s, while the pressure of the upper telescopic cylinder 1 is adjusted within the range of 800 kg to 460 kg. The displacement of the two telescopic cylinders is synchronized. The pressure adjustment of the upper telescopic cylinder 1 is as follows: when the magnetically pressed product 14 is completely inside the mold cavity, the upper telescopic cylinder 1 applies a maximum pressure of 800 kg to suppress cracking or powder layer peeling caused by uneven stress in the early stages of demolding. As the pressed product 14 gradually emerges from the mold cavity, the pressure of the upper telescopic cylinder 1 decreases at a rate of approximately 20-30 kg per millimeter to ensure that the exposed part of the product gradually releases stress and avoids local stress concentration. When the product 14 is completely removed from the mold cavity, the pressure of the upper telescopic cylinder 1 drops to the minimum value of 460 kg. At this point, the product has been completely demolded, and the pressure release is complete, ensuring that the pressed product 14 has a complete structure, is free of cracks, and has no chipped corners. The entire variable pressure demolding process is adjusted in real time by the PLC program based on the feedback from the displacement sensor of the lower telescopic cylinder 12, realizing closed-loop control and ensuring that the demolding process is stable, controllable and repeatable.

[0047] The execution of each of the above processes is achieved through precise automatic control via PLC programming.

[0048] In this embodiment, the magnetizing orientation capacitor C is 12500μF with a charging voltage of 2400V; the demagnetizing capacitor C2 is 2500μF with a voltage of 2400V; the magnetizing magnetic field is 3T, and the magnetizing interval is 0.5s; the pressure ratio between the upper telescopic cylinder 1 and the lower telescopic cylinder 12 is 2:1, and the pressing speed of the upper telescopic cylinder 1 is 100mm / s, while the pressing speed of the lower telescopic cylinder 12 is 50mm / s; the holding time is 2s; after molding, sintering and aging treatment are performed to obtain the finished product;

[0049] The final compressed density is 4.0 g / cm³. 3 The total forming time is 8 seconds, including 3 seconds of charging and demagnetizing time, 0.05 seconds of reaching the rated magnetic field, and 4.95 seconds of molding time. The molding process data is shown in the table below:

[0050] <![CDATA[Preloading density (g / cm 3 )]]> shape Remanence (T) Remark 2.0 The upper surface is noticeably curved 14.25 A 0.6mm dent appeared. 2.5 Slight bending of the upper surface 14.32 3.0 Slight bending of the upper surface 14.18 3.3 Slight bending of the upper surface 14.03 3.5 Smooth upper surface 13.9

[0051] For comparison, this iron-boron magnetic powder exhibits a magnetic induction intensity of 1.6T in a conventional DC magnetic field and a forming density of 4.0 g / cm³. 3 isostatic density 4.5 g / cm³ 3 Under the given conditions, the remanence was 14.20T, with a bending of 0.3mm, and the total forming time was 15s, including 6s for charging and demagnetizing, and 9s for current rise / fall and pressing. Comparatively, this invention significantly shortens the charging and demagnetizing time, resulting in a substantial improvement in pressing efficiency.

[0052] On the other hand, in order to verify the quality of the finished product at each pressing density, the following examples were performed:

[0053] Example 2:

[0054] The final compressed density is 4.10 g / cm³. 3 Other molding conditions were the same as in Example 1, and the results are shown in the table below:

[0055] <![CDATA[Preloading density (g / cm 3 )]]> shape Remanence (T) Remark 2.0 The upper surface is noticeably curved 14.20 There is a 0.4mm dent. 2.5 Slight bending of the upper surface 14.28 3.0 Slight bending of the upper surface 14.12 3.3 Smooth upper surface 14.1 3.5 Smooth upper surface 13.86

[0056] Example 3:

[0057] Final compressed density: 4.3 g / cm³ 3 Other molding conditions were the same as in Example 1, and the results are shown in the table below:

[0058] <![CDATA[Preloading density (g / cm 3 )]]> shape Remanence (T) Remark 2.0 The upper surface is noticeably curved 14.1 There are fine cracks 2.5 Slight bending of the upper surface 14.2 3.0 Slight bending of the upper surface 14.2 3.3 Smooth upper surface 14.1 3.5 Smooth upper surface 13.8

[0059] As can be seen from the data in Examples 1 to 3, the pulse magnetic field forming press can significantly shorten the charging and demagnetizing time and significantly improve the pressing efficiency, while achieving structural stability of products under different pressing densities.

Claims

1. A pulse magnetic field forming press, comprising a support platform (3), an upper beam (2), a lower beam (10), a guide column (4), a feeder (18), a sealed chamber (19), and a forming assembly, wherein the lower beam (10) is fixed on the support platform (3), the upper beam (2) is located above the lower beam (10) and the two are connected by the guide column (4), the sealed chamber (19) is disposed between the upper beam (2) and the lower beam (10), the forming assembly is placed inside the sealed chamber (19), and the feeder (18) is installed on one side of the sealed chamber (19), characterized in that: It also includes a tray (7), a mold frame (8), a pulse electromagnet and a pulse control circuit. The tray (7) is fixed above the lower beam (10) via the mold frame (8). The pulse electromagnet is installed on the tray (7) and driven by the pulse control circuit. The pulse electromagnet is horizontally U-shaped and consists of a pulse orientation coil (5) and an iron core (6). The iron core (6) is made of silicon steel sheets or pure iron sheets with insulating varnish on the surface, which are stacked alternately. The thickness of a single sheet is 0.1-5mm and the sheets are insulated from each other. The pulse width output by the pulse electromagnet is 5-20ms, the magnetic field strength is 1-5T, and the orientation pulse is applied 2-5 times. The pulse control circuit includes a power switch (J1), a constant power regulator (H), a step-up transformer (B), a rectifier circuit, a magnetization circuit, and a demagnetization circuit. The magnetization circuit includes at least two sets of magnetization orientation capacitors (C) and orientation thyristors (K1). Each set of magnetization orientation capacitors (C), orientation thyristors (K1) and pulse orientation coil (5) constitutes a pulse circuit. The magnetization orientation capacitors (C) are charged simultaneously and discharged separately. The at least two sets of magnetization orientation capacitors (C) and their corresponding orientation thyristors (K1) are configured to be turned on in turn to apply multiple pulse magnetic fields to the pulse orientation coil (5). The demagnetizing circuit includes a demagnetizing capacitor (C2), a demagnetizing bidirectional thyristor (K2), and a pulse orientation coil (5).

2. The pulse magnetic field forming press according to claim 1, characterized in that: The pulse orientation coil (5) is made of a hollow copper tube covered with an insulating layer. Cooling water flows through the hollow copper tube and a circulating pump is connected to it.

3. The pulse magnetic field forming press according to claim 1, characterized in that: The forming assembly includes a mold (15), an upper telescopic cylinder (1), an upper punch (13), a lower telescopic cylinder (12), and a lower punch (16). The mold (15) is fixed in the middle of the support plate (7). The upper telescopic cylinder (1) is installed in the middle of the upper beam (2) and its piston end is detachably connected to the upper punch (13). The lower telescopic cylinder (12) is installed in the middle of the lower beam (10) and its piston end is detachably connected to the lower punch (16). The upper punch (13), the mold (15), and the lower punch (16) are aligned along the same vertical axis.

4. The pulse magnetic field forming press according to claim 3, characterized in that: The mold (15) is composed of a magnetic plate (9) and a non-magnetic block (17), and its overall resistivity is greater than 0.5 × 10⁻⁶. -6 Ω·m.

5. The pulse magnetic field forming press according to claim 3, characterized in that: The upper telescopic cylinder (1) and the lower telescopic cylinder (12) are servo electric cylinders or hydraulic cylinders.

6. A pulsed magnetic field forming method, performed using the press described in any one of claims 1-5, characterized in that... Execute in sequence: S1. Spray release agent onto the inner wall of the mold cavity of the mold (15) and the surfaces of the upper die punch (13) and lower die punch (16) that are in contact with the powder, add magnetic powder into the mold cavity, and fill the sealed chamber (19) with nitrogen until the oxygen content is ≤200ppm; S2. Start the upper telescopic cylinder (1) to drive the upper die punch (13) to pre-press the magnetic powder, so that the pre-press density reaches 2.2-3.5g / cm³. 3 ; S3. Apply the first pulse magnetic field, then maintain the pressure ratio between the lower telescopic cylinder (12) and the upper telescopic cylinder (1) at 1:(2-10) for floating pressing. Apply the next pulse every 0.1-0.5 seconds until the density is finally compressed to 4.0-4.3 g / cm³. 3 And maintain pressure; S4 turns on the demagnetizing bidirectional thyristor (K2), and the demagnetizing circuit works to remove residual magnetism; S5. Control the piston of the lower telescopic cylinder (12) to move upward, and the molded product is ejected by the lower die punch (16) to complete the demolding.

7. The pulsed magnetic field shaping method according to claim 6, characterized in that: During the demolding stage, variable pressure protection is used for demolding, and the pressure of the upper telescopic cylinder (1) gradually decreases from 800 kg to 460 kg; each process from S1 to S5 is precisely and automatically controlled by PLC programming.

Images