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Electromagnetic containment of continuously cast liquid metal by a superconducting magnet

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Superconducting upward casting of metals

A new novel technique for casting aluminium strips has been devised. The method can also be applied for steel casting. It is expected to increase the casting speed several times.

Industrial Technologies

One of the major industrial processes for shaping metals is pouring liquid metal into a mould, i.e. casting. There are a dozen commercial casting processes, among them sand casting, die casting and role casting. The use of twin-role casting is a common process used in the aluminium industry. This method of continuous casting produces aluminium plates of 5mm thickness and variable width depending upon the width of the two steel rolls used. The method consists of introducing liquid aluminium between the two rolls that slowly turn. The metal comes out of the device completely solidified into the shape of stripes. The rotation speed of the rolls is the production speed of aluminium and the increase of this speed is one of the main goals of the aluminium industry. The current project has designed, produced and tested an experimental device that can increase productivity several times by supplying the melt vertically upwards. The melt is being lifted by an upward Lorenz force created by an electric current supplied into the melt in a direction normal to the rolls axes and a magnetic field oriented along the axis of the rolls. A superconducting magnet creates this magnetic field of 0.5Tesla. The device was able to produce aluminium stripes of 0.5m width using rolls of 0.15m radius at a casting speed of 0.2m/s. The current trough the melt had a value of 3kA. An electromagnetic containment of the melt on the space below and between the rollers has also been experimentally demonstrated and is expected to help improve the structure and surface of the casting products. The proposed method may find wide use in the automotive, aerospace and hi-tech commercial industries where excessive use of steel and non-ferrous metal sheets is being made.

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