GB820321A - Low frequency induction heating apparatus - Google Patents

Abstract

820,321. Induction heating apparatus. MAGNETHERMIC CORPORATION. Jan. 10, 1956 [Jan. 10, 1955], No. 861/56. Class 39(3) Low-frequency, i.e. 25 to 60 cycles, induction heating apparatus for treating billets and other metallic charges of different lengths comprises a coil 1 of an electrically insulated conductor having taps 2 and mounted between plate 3, 4 which are drawn together by means of rods 5 to clamp the convolutions of the coil; a sleeve 7, which is preferably non-magnetic and may be of a refractory material, lines the coil. A carriage 14 for a core support 20 is movably mounted on sleeves 12 axially of the coil 1 and is normally urged towards the plate 4 by compression springs 19. A laminated core 22 having alternate layers of steel or ferrous metal 23 and metal of high heat conductivity 24, e.g. copper, is mounted on the support 20 which comprises a hollow sleeve telescopically fitting a sleeve 15 of the carriage 14. The sleeve 15 has a clamping latch 21 so that the support 20 may be secured in different positions axially of the coil 1. The support 20 also carries a water pipe 25 for cooling the core 22 and is closed at its upper end by a cap 29 having a port 30 for introducing a reducing or non-oxidizing gas through the support 20 and into the sleeve 7. If the apparatus is to be used in the upright position shown and the gas is helium or other gas lighter than air, the bottom of the sleeve 7 may be left open. If the apparatus is to be used in other than a vertical position or with a heavierthan-air gas, a seal may be provided at the end 8 of the coil. A piston 33, for feeding billets or ingots into the end 8 of the coil, is movable into the sleeve 7, and heat insulating pads 34, 35 reduce heat losses from the ends of the billet. In addition to the cross-sectional dimension of the conductor of the coil 1 increasing longitudinally of the coil as shown, the cross-sectional dimension of the conductor radially of the coil may differ in different parts of the coil. Alternatively, the turns of the coil may be spaced progressively farther apart the farther they are from the charging end 8, correspondingly thicker insulation being interposed between the turns to permit clamping of the coil as before. The conductor may be of the tubular, water-cooled type. The core 22 concentrates the flux of that portion of the coil 1 which is beyond the upper end of the billet and the provision for longitudinal adjustment of the core permits billets of different lengths to be securely held.