GB600669A - Improvements in and relating to the heating of moulding materials by high-frequency electric fields - Google Patents

Abstract

600,669. Dielectric heating. GENERAL ELECTRIC CO., Ltd., LEYTON, E. M., and NELSON, H. M. April 30, 1945, No. 10849. [Class 39(iii)] Pellets or preforms of moulding material are arranged in contact with, or adjacent to, an electrode having a co-operating electrode comprising independently movable elements each maintained in contact, or substantially in contact, with one of the pellets which are then heated by a highfrequency electric field induced between the electrodes. Thus a frame 1 is mounted on legs 2 and carries a rectangular plate 3 which supports a number of electrode elements 4 in register with apertures 10 in an insulating loading board 6 resting on a platform 5 which is slidably mounted vertically on the legs 2 by toggle levers 7, 8 with a control arm 9. The pellets are supported in the apertures 10 by a removable electrode plate 11. If the board 6 has recesses only it may itself form the lower electrode. Each electrode element 4 comprises a member 13 fixed to the plate 3 and a member 12 carrying a plate 41, the members being extended telescopically by a spring 14 to an extent limited by a rod 16. Thus after raising the platform 5, or alternatively lowering the frame 1, the electrode plates 4<1>, which are of smaller diameter than the apertures 10, are yieldably maintained in contact with the pellets. The electrode elements 4 may be grouped into spring-mounted units comprising, for example, two or three electrode elements tiltable about one or two suitable horizontal axes respectively. The electrodes are connected to a high-frequency electric source by leads 19, 20 the latter having connections 18 to the rods 16 if the plate 3 is non-conductive. The apparatus may be mounted in a chamber or oven having a door operating the arm 9. After heating, the board 6 may be located over a mould having cavities into which the pellets drop on withdrawing the supporting electrode 11.