GB794598A - Inductors for heating cylinders - Google Patents

Abstract

794,598. Induction heaters for cylinders. WILD - BARFIELD ELECTRIC FURNACES, Ltd. Sect. 10, 1956 [Sept. 15, 1955], No. 26494/55. Class 391(3) A low frequency induction heating device is in the form of a cuff which may be used for heating the cylinders leading to the nozzles of plastic moulding machines. In Fig. 2, a brass tube 1 carries a winding 2 of aluminium wire covered with glass fibre and silicone resin, and a casing comprises a mild steel member 3 provided with annular end plates 4. The tube 1 and the member 3 are split longitudinally to minimise the formation of induced currents and the plates have radial slots 5 to enable the device to be clamped on an extrusion cylinder 10. The surface of the cylinder 10, together with the casing 3 and end plates 4, forms a closed magnetic circuit. In a modification, Fig. 4, the tube 1 is of stainless 'steel and is not split longitudinally. The plates 4 are not slotted and enclose a water-tight annular space 14 through which water may be circulated for cooling the cylinder after it has been heated; a baffle plate 11 is provided in the space 14. A number of the cuffs may be arranged successively along a cylinder and may be independently controlled automatically or by hand. The windings may be energized by 50 c.p.s. mains supply.