1、 General introduction of electromagnetic assisted forming system
Electromagnetic forming belongs to high-energy (high-speed) forming technology. Firstly, the electric energy needs to be stored in the high-voltage capacitor. When the high-voltage switch is closed, the energy storage capacitor will discharge the coil quickly（ When the magnetic field passes through the workpiece, the induced current (eddy current) will be generated in the metal workpiece. When the charged metal workpiece is in the rapidly changing magnetic field, it will be affected by the magnetic force. When the magnetic pressure reaches the yield strength of the material, the metal workpiece will have plastic deformation to achieve the purpose of forming metal parts. Electromagnetic forming technology has the characteristics of easy and accurate control of processing energy, fast forming speed, high precision of forming workpiece, small elasticity of parts after forming, improvement of plastic deformation ability of materials, simple mold and strong universality of equipment, easy to adopt composite process and realize automatic production, green and environmental protection in the whole forming process, which has been widely used in aviation, aerospace, weapon industry Automobile manufacturing, light chemical industry, instruments and electronics and many other fields.
Electromagnetic forming powder compactor belongs to high energy rate impact compaction, which can increase the compaction density of ceramic powder, cemented carbide, magnet and other powder by 20-50% compared with ordinary compaction, and is very suitable for high density compaction of nano materials.
2、 Electromagnetic powder pressing Powder metallurgy is an effective way to produce all kinds of high-performance structural materials and functional materials. The key to promote the application and development of powder materials is to research and develop the integrated technology of high-density, high-performance and near final formed powder products. It is an effective way to obtain high-density powder metallurgy products by pressing powder materials with strong impact. In the s, researchers from various countries competed to study explosive forming, which played a great role in improving the density of superhard powder pressing. However, due to the poor repeatability and low automation of explosive forming process, its application was limited. Electromagnetic pressing is also a high energy rate forming method, and it is superior to explosive forming in terms of forming energy and speed control. Firstly, the idea of electromagnetic forming is introduced into powder material pressing, and the bar, strip and more complex parts are pressed by the method of voltage releasing. By screening the particle size of powder, the bar and strip with sharp angle can be successfully manufactured. Since then, we have tried to mix refractory materials and low melting point metals to obtain high-density products, and then scholars in various countries have also done some follow-up research. Electromagnetic forming machine generally consists of three parts: charging circuit, discharging circuit and control circuit. Charging circuit is an important part of electromagnetic forming machine. It must charge energy storage capacitor reliably and efficiently. The charging circuit includes the first level DC power supply, the second level switch charging power supply, step-up transformer, rectifier circuit and corresponding protection circuit. The energy of the energy storage capacitor is the voltage at both ends of the energy storage capacitor. It can be seen that the energy storage capacity and the charging voltage are two important factors affecting the energy. Electromagnetic suppression part The vacuum electromagnetic powder pressing part includes a powder pressing coil, a mould, an inert gas table and a vacuum system. Installation of powder pressing coil and workpiece (it can be installed in the press when the workload is large. If oxygen free welding is required, it can be installed in the airtight environment of argon without oxygen. The oxygen content can be up to 1ppm. The powder is sealed and vacuumized in the mold, and then pressed