Electromagnetic powder compaction device and method based on pulse electromagnetic force

Abstract

The invention discloses an electromagnetic powder compaction device and method based on pulse electromagnetic force. The device comprises a forming coil, a magnetic field shaper, a driving pipe, a steel plug and a filling pipe. The forming coil is connected with an alternating current power supply; the magnetic field shaper, the driving pipe, the steel plug and the filling pipe are located in the forming coil. The driving pipe is positioned above the steel plug and the filling pipe; the steel plugs are located on the left side and the right side of the filling pipe, the filling pipe is filled with powder, and the filling pipe deforms under the action of the driving pipe, so that powder compaction is achieved. According to the electromagnetic powder compaction device and method based on the pulse electromagnetic force, the powder compaction process can be completed within millisecond time, and the powder compaction efficiency is greatly improved; the use of molds can be effectively reduced, and the production cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of pulsed electromagnetic force forming technology, specifically to an electromagnetic powder compaction device and method based on pulsed electromagnetic force. Background Technology

[0002] Powder metallurgy technology is widely used in industrial manufacturing due to its unique advantages of high productivity and near-net-shape machining. Through powder metallurgy, special functional materials and high-performance structural materials can be produced, exhibiting characteristics such as material saving, energy saving, low cost, and no pollution. This is of great significance in contributing to the achievement of lightweight and low-carbon green material goals.

[0003] In the powder metallurgy process, powder compaction is a key step in improving product density and ensuring dimensional accuracy. However, existing powder compaction technologies, such as explosive compaction, isostatic compaction, and rolling compaction, suffer from drawbacks such as high mold requirements, long production cycles, inability to compact special materials, and high temperature requirements, which seriously affect the precision and production efficiency of powder metallurgy products.

[0004] Chinese patent "A Method and Apparatus for Powder Pressing Using Radial and Axial Electromagnetic Forces" (application number: 201810002766.1) discloses a method for pressing powder simultaneously or in stages using radial and axial electromagnetic forces. The radial electromagnetic force is achieved using a solenoid coil, through which a pulsed current is passed, inducing a large pulsed current and a pulsed electromagnetic force on the metal powder. Sintering is achieved through the thermal effect generated by the large pulsed current, and the magnitude of the pulsed electromagnetic force causes the metal powder to alternately undergo elastic deformation and elastic recovery, breaking down oxides between powder particles and reducing friction, ultimately increasing the pressing density. However, this device has a complex structure, requiring multiple precision components, making it difficult to operate. Furthermore, the device lacks an active control mechanism for the magnetic field distribution, resulting in uneven force distribution in different areas of the powder and potentially leading to uneven powder compaction. Summary of the Invention

[0005] This invention proposes an electromagnetic powder compaction device and method based on pulsed electromagnetic force, which can complete the powder compaction process in milliseconds, greatly improving the powder compaction efficiency; it can effectively reduce the use of molds and significantly reduce production costs.

[0006] The technical solution adopted in this invention is as follows: An electromagnetic powder compaction device based on pulsed electromagnetic force, the device comprising: Forming coil, magnetic field shaper, drive tube, steel plug, filling tube; The forming coil is connected to an AC power source. The magnetic field shaper, drive tube, steel plug, and filling tube are located inside the forming coil; The drive tube is located above the steel plug and the filling tube; The steel plugs are located on the left and right sides of the filling tube. The filling tube is filled with powder, and the filling tube deforms under the action of the driving tube, thereby achieving powder compaction.

[0007] The device also includes: capacitor bank C, resistor R, inductor L, switch S1, and switch S2; One end of switch S1 is connected to the AC power supply. The other end of switch S1 is connected to one end of capacitor bank C and one end of resistor R. The other end of resistor R is connected to one end of inductor L. The other end of inductor L is connected to one end of the forming coil. The other end of the AC power supply is connected to the other end of capacitor bank C and one end of switch S2, and the other end of switch S2 is connected to the other end of the forming coil.

[0008] The formed coil is a solenoid coil with multiple turns, and epoxy resin is applied between each turn of the coil.

[0009] The magnetic field shaper consists of two symmetrical trapezoidal shaping units. The tops of the two shaping units are arranged opposite each other, and a slit for magnetic field focusing is reserved between the tops of the two units. The waist and bottom edges of the two trapezoidal units form a smooth transition of the overall structure.

[0010] The forming coil and the magnetic field shaper are connected as a single unit.

[0011] Powder compaction method: The pulsed magnetic field generated by the forming coil and the induced eddy current generated by the magnetic field shaper work together to generate a pulsed electromagnetic force that acts on the drive tube to achieve powder compaction.

[0012] The electromagnetic powder compaction process consists of two parts: a charging process and a discharging process. The charging process is as follows: switch S1 is closed, switch S2 is open, and AC power charges capacitor bank C to the required power supply voltage; when charging is complete, switch S1 is opened. The discharge process is as follows: switch S2 is closed, switch S1 is open, capacitor bank C discharges, and the discharge current passes through resistor R, inductor L, and forming coil in sequence to form a closed circuit.

[0013] When the system starts discharging, the pulsed large current will induce eddy currents on the outer surface of the magnetic field shaper. Due to the skin effect, the eddy currents approach the outer surface; the induced eddy currents flow through the slit to the inner surface of the magnetic field shaper, forming a loop.

[0014] The inner surface area of ​​the magnetic field shaper is smaller than that of the outer surface area, so the eddy current density is greater there.

[0015] This invention discloses an electromagnetic powder compaction device and method based on pulsed electromagnetic force, with the following technical advantages: 1) By passing current through the forming coil, a pulsed magnetic field is generated in the coil. The changing magnetic field induces eddy currents on the surface of the metal tube. The magnetic field and the induced eddy currents work together to generate a pulsed electromagnetic force, which drives the metal tube to compact the powder.

[0016] 2) This invention introduces a magnetic field shaper to change the magnetic field distribution and ensure sufficient pulsed electromagnetic force during the powder processing.

[0017] 3) The device and method proposed in this invention can effectively reduce the use of molds and greatly reduce production costs.

[0018] 4) The device and method of the present invention can complete the powder compaction process in milliseconds, which greatly improves the powder compaction efficiency.

[0019] 5) This invention avoids the influence of temperature on the powder compaction process, realizes the preparation of various composite materials, and can be extended to special scenarios and special material compaction.

[0020] 6) In this invention, the forming coil and the inverted trapezoidal magnetic field shaper are integrated, so that the pulsed magnetic field is more focused on the area of ​​the powder to be compacted, so that the powder is subjected to more uniform force, thereby improving the uniformity and accuracy of compaction. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the electromagnetic powder compaction device described in this invention.

[0022] Figure 2 This is a circuit control diagram of the electromagnetic powder compaction device described in this invention.

[0023] Figure 3 This is a schematic diagram of the magnetic field shaper structure.

[0024] Figure 4 This is a schematic diagram of the current direction in a magnetic field shaper.

[0025] Figure 5(a) is a schematic diagram of the three-dimensional structure of the magnetic field shaper; Figure 5(b) is a schematic diagram of the cross-sectional structure of the magnetic field shaper.

[0026] Wherein: 1-forming coil, 2-magnetic field shaper, 3-driving tube, 4-steel plug, 5-filling tube, 6-slit, 7-inner surface, 8-outer surface, 9-current inflow direction, 10-current outflow direction, 11-current direction on the outer surface of the magnetic field shaper, 12-current direction on the inner surface of the magnetic field shaper, 13-pulse electromagnetic force. Detailed Implementation

[0027] like Figure 1As shown, the electromagnetic powder compaction device includes: a magnetic field shaper 2, a drive tube 3, a steel plug 4, and a filling tube 5 located inside the forming coil 1; the drive tube is located above the steel plug 4 and the filling tube 5; the steel plug 4 is located on the left and right sides of the filling tube 5. The electromagnetic powder compaction process consists of two parts: a charging process and a discharging process. The charging process mainly involves: S1 closure, S2 Disconnect the power supply, and the AC power source will charge the capacitor bank to the required voltage. Disconnect the power supply again after charging is complete. S1 . Figure 2 The red arrow in the middle indicates the charging process. The discharging process mainly consists of: S2 closure, S1 When disconnected, the capacitor bank discharges, and the discharge current sequentially passes through the line resistor, line inductance, and forming coil 1 to form a closed loop. In this invention patent, the discharge time is only 300 seconds. To achieve rapid discharge, Figure 2 The green arrow in the middle indicates the discharge process.

[0028] The selected forming coil 1 is a solenoid coil with a total of 10 turns and a cross-sectional radius of 8mm for each turn. The spacing between single turns is 2mm, and epoxy resin is applied between each turn to prevent electrical effects between single turns during discharge. Because the forming coil 1 requires high conductivity, pure copper is selected as the material in this invention. When current flows through the forming coil 1, a strong pulsed magnetic field is generated. This, in turn, generates induced eddy currents on the surface of the metal material, thereby producing a powerful, instantaneous pulse of electromagnetic force.

[0029] The magnetic field shaper 2 is an auxiliary tool, and this invention uses pure copper material. The inverted trapezoidal magnetic field shaper 2 can change the magnetic field distribution, making the strength of the magnetic field controllable within the compaction area, thus achieving flexible compaction.

[0030] Figure 3 The diagram shows the structure of the magnetic field shaper 2, including the slit 6, the inner surface 7, and the outer surface 8. Figure 5(a) is a three-dimensional structural diagram of the magnetic field shaper 2; Figure 5(a) is a cross-sectional structural diagram of the magnetic field shaper 2.

[0031] When the system begins to discharge, the pulsed large current induces eddy currents on the outer surface 8 of the inverted trapezoidal magnetic field shaper. Due to the skin effect, the eddy currents approach the outer surface 8. The induced eddy currents flow through the slit 6 to the inner surface 7 of the magnetic field shaper 2, forming a loop. Figure 4 The direction of the current in the magnetic field shaper 2 is shown. The inner surface area of ​​the inverted trapezoidal magnetic field shaper is smaller than the outer surface area, so the eddy current density is greater here, which achieves the effect of strengthening the magnetic field in the compaction area.

[0032] The skin effect experienced by the magnetic field shaper 2 can be expressed as: (1); in, For skin depth; The permeability of the magnetic field shaper 2; The conductivity of the magnetic field shaper 2; The magnetic field frequency; The pulsed magnetic field generated by the forming coil 1 and the induced eddy current generated by the magnetic field shaper 2 work together to generate a pulsed electromagnetic force 13 that acts on the drive tube 3 to achieve powder compaction. The forming coil 1 and the inverted trapezoidal magnetic field shaper are integrally connected. The two are welded together under high temperature and high pressure conditions to form an integral structure that is seamless, detachable, and has high connection strength, good structural stability, and can adapt to the precision requirements of magnetic field control scenarios. Figure 1 It can be observed that the forming coil 1 is connected to the magnetic field shaper 2.

[0033] The forming coil 1 is integrally connected with the magnetic field shaper 2, which can achieve precise control of the spatial distribution of the magnetic field, so that the pulse magnetic field is more focused on the area of ​​the powder to be compacted, making the powder more uniformly stressed, thereby improving the uniformity and accuracy of compaction, which is beneficial for manufacturing parts with complex shapes and high precision requirements. The forming coil 1 of this invention uses a solenoid coil. Ignoring the asymptote effect of the solenoid coil, the solenoid coil can be considered as several axially distributed coaxial closed loops. Therefore, due to its structural influence, the eddy current density only has a circumferential component. Therefore, the pulsed electromagnetic force on the driving transistor can be expressed as: (2); Al alloy materials have advantages such as low density and high strength. The use of Al 6063 alloy material in drive tube 3 helps to compact powder quickly and accurately. The steel plug 4 is made of steel to fix the powder during the compaction process. The packing tube 5 is filled with powder, and the packing tube 5 deforms under the action of the drive tube, thereby achieving powder compaction.

Claims

1. An electromagnetic powder compaction device based on pulsed electromagnetic force, characterized in that the device... include: Forming coil (1), magnetic field shaper (2), drive tube (3), steel plug (4), filling tube (5); The forming coil (1) is connected to an AC power source; The magnetic field shaper (2), drive tube (3), steel plug (4), and filling tube (5) are located inside the forming coil (1); The drive tube (3) is located above the steel plug (4) and the filling tube (5); The steel plug (4) is located on the left and right sides of the filling tube (5); The filling tube 5 is filled with powder, and the filling tube 5 deforms under the action of the driving tube 3, thereby achieving powder compaction.

2. The electromagnetic powder compaction device based on pulsed electromagnetic force according to claim 1, characterized in that: The device also includes: capacitor bank C, resistor R, inductor L, switch S1, and switch S2; One end of switch S1 is connected to one side of AC power supply. The other end of switch S1 is connected to one end of capacitor bank C and one end of resistor R. The other end of resistor R is connected to one end of inductor L. The other end of inductor L is connected to one end of forming coil (1). The other end of the AC power supply is connected to the other end of the capacitor bank C and one end of the switch S2. The other end of the switch S2 is connected to the other end of the forming coil (1).

3. The electromagnetic powder compaction device based on pulsed electromagnetic force according to claim 1, characterized in that: The shaped coil (1) is a solenoid coil with multiple turns, and epoxy resin is applied between each turn of the coil.

4. The electromagnetic powder compaction device based on pulsed electromagnetic force according to claim 1, characterized in that: The magnetic field shaper 2 consists of two symmetrical trapezoidal shaping units. The tops of the two shaping units are arranged opposite each other, and a slit (6) for magnetic field focusing is reserved between the tops of the two units. The waist and bottom edges of the two trapezoidal units form a smooth transition overall structure.

5. The electromagnetic powder compaction device based on pulsed electromagnetic force according to claim 1, characterized in that: The forming coil (1) and the magnetic field shaper (2) are connected as a whole.

6. A powder compaction method using an electromagnetic powder compaction device as described in any one of claims 1 to 5, characterized in that: The pulsed magnetic field generated by the forming coil (1) and the induced eddy current generated by the magnetic field shaper (2) work together to generate a pulsed electromagnetic force (13) which acts on the drive tube (3) to achieve powder compaction.

7. The powder compaction method according to claim 6, characterized in that: The electromagnetic powder compaction process includes a charging process, which is as follows: switch S1 is closed, switch S2 is open, and AC power is used to charge capacitor bank C to the required power supply voltage; when the charging is completed, switch S1 is opened.

8. The powder compaction method according to claim 7, characterized in that: The electromagnetic powder compaction process includes a discharge process, which is as follows: switch S2 is closed, switch S1 is open, capacitor bank C discharges, and the discharge current passes through resistor R, inductor L, and forming coil (1) in sequence to form a closed loop.

9. The powder compaction method according to claim 8, characterized in that: When the system starts to discharge, the pulsed large current will induce eddy currents on the outer surface (8) of the magnetic field shaper (2). Due to the skin effect, the eddy currents are close to the outer surface (8). The induced eddy currents flow through the slit (6) to the inner surface (7) of the magnetic field shaper (2) to form a loop.

10. The powder compaction method according to claim 9, characterized in that: The area of ​​the inner surface (7) of the magnetic field shaper (2) is smaller than that of the outer surface (8), so the eddy current density is greater here.

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