In addition to the converters for the provision of power, the coils play a central role as a tool for power transmission into the workpiece.
For this purpose, the alternating current generated by the converter is fed through a copper conductor and generates an alternating magnetic field, which in turn induces eddy currents in the workpiece without contact, which leads to heating. This assumes that the workpiece is made of an electrically conductive material.
As a rule, the copper conductor of the coil must be water or air-cooled, since the high currents lead to line losses and therefore to heat, which must be dissipated.
In order to achieve a high level of efficiency, the coil must be adapted to the workpiece to be heated and the process in an optimum way. The coil optimisation parameters are the copper profile used, the number of windings, the turn spacing and the number of layers.
For the inductive heating of billets of different materials for extrusion, IAS mainly uses specially tuned, multi-layer induction coils with several zones, which are characterised by high efficiency and economy. In some applications, single-layer coils with taps are used to cover different block lengths.
In conjunction with magnetic flux guidance systems and stainless steel housings, electrical efficiencies of over 80% are achieved.