GB577208A - Improvements in or relating to the electric heating of dielectric materials - Google Patents

Abstract

577,208. Electric induction heating. STANDARD TELEPHONES & CABLES, Ltd., and MADDOCK. A. J. Nov. 19, 1943, No. 19375. [Class 39 (iii)] In the heating of a dielectric by the application of a high frequency electric field between electrodes, one or both electrodes is or are so shaped or arranged that a different heating effect is obtained at different parts of the material. Thus, in heating a disc, one of the electrodes may be of dished shape so that the greatest heating is obtained at the centre. If the highest temperature is desired at the edges of a sheet S, Fig. 2, one of the electrodes C' is curved, or the electrode may be stepped as in Fig. 3 to obtain banded temperature zones. A gradual temperature gradient may be obtained by an inclined electrode, flat or curved. Any desired temperature distribution may be obtained by suitably shaping one electrode, e.g., by dishing it in the form of a cross or a dimple. Where glass or other vitreous solid is to be fused, a high temperature may be obtained at the point of fusion with a gradual temperature fall from this region. Materials passed between the electrodes may be subjected to a low temperature, increasing to a high temperature, or vice versa. Several electrodes each at a different height above a single electrode, may be connected in parallel. Specification 567,731 is referred to. Reference has been directed by the Comptroller to Specification 555,054.