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Electromagnetic forming (EM forming or magneforming) is a type of high velocity, cold process for electrically conductive metals, most commonly copper and aluminium. The workpiece is reshaped by high intensity pulsed magnetic fields that induce a current in the workpiece and a corresponding repulsive magnetic field, rapidly repelling portions of the workpiece. The workpiece can be reshaped without any contact from a tool, although in some instances the piece may be pressed against a die or former. The technique is sometimes called ''high velocity forming'' or ''electromagnetic pulse technology''. == Explanation == A special coil is placed near the metallic workpiece, replacing the pusher in traditional forming. When the system releases its intense magnetic pulse , the coil generates a magnetic field which in turn accelerates the workpiece to hyper speed and onto the die. The magnetic pulse (MP) and the extreme deformation speed transforms the metal into a visco-plastic state – increasing formability without affecting the native strength of the material (magnetic pulse forming illustration ). A rapidly changing magnetic field induces a circulating electric current within a nearby conductor through electromagnetic induction. The induced current creates a corresponding magnetic field around the conductor (see Pinch (plasma physics)). Because of Lenz's Law, the magnetic fields created within the conductor and work coil strongly repel each other. In practice the metal workpiece to be fabricated is placed in proximity to a heavily constructed coil of wire (called the ''work coil''). A huge pulse of current is forced through the work coil by rapidly discharging a high voltage capacitor bank using an ignitron or a spark gap as a switch. This creates a rapidly oscillating, ultrastrong electromagnetic field around the work coil. The high work coil current (typically tens or hundreds of thousands of amperes) creates ultrastrong magnetic forces that easily overcome the yield strength of the metal work piece, causing permanent deformation. The metal forming process occurs extremely quickly (typically tens of microseconds) and, because of the large forces, portions of the workpiece undergo high acceleration reaching velocities of up to 300 m/s. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Electromagnetic forming」の詳細全文を読む スポンサード リンク
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