Localised heater for steel bar - produces Joule effect heating for uniform cross=sectional influence enabling bar to be sheared

摘要

The system permits localised heating of a small section of a steel bar, e.g. for use in shearing a bar with a large cross section. The bar (1) is threaded through a magnetic core, whose shape corresponds to the cross section of the bar. A primary winding (3) is carried on one side of the core and may be connected to a source of alternating current. A series of secondary windings (5a-g) are formed on the remaining sides of the core, and have equal numbers of turns. The secondary windings are connected in series with windings (5a-d) wound in one direction and the remainder in the other direction. The terminations of each of the secondary windings are connected to electrical contacts disposed in the same plane and attached in pairs to the face of the bar. When current is applied to the primary, a high current flows between the contacts and Joule effect heating takes place in the bar.