GB298324A - Improvements relating to the production of castings free from blow-holes - Google Patents

Abstract

298,324. Heraeus Vacuumschmelze Akt.-Ges., and Rohn, W. Aug. 15, 1927. Induction furnaces.-Blocks or sheets, suitablefor rolling into plates, or other metal articles are made by melting metal and then cooling it from the bottom up in a crucible of the shape required. The heating is done by high frequency or induction coil f which after melting is moved relatively to the crucible a. That part of the crucible exposed may be cooled by a water coil e. In a modification the coil f, Fig. 4, may be tapped at g and cut in sections from the bottom. The method of Specification 226,801, [Class 51 (ii), Furnaces and kilns applying &c.], may be employed in making the crucible for instance material t, which does not sinter at the temperatures employed, is inserted between the coil f and a sleeve m then material o which will sinter is inserted between this and a sleeve n in which the material is placed. The sleeve m is then removed and the current applied. As the upper end of the crucible may be insufficiently heated to sinter, a ring p of refractory material may be used; the crucible may also be closed with a refractory cover or granular refractory material. After the metal has solidified, blocks k are withdrawn the material l falls out and the crucible is withdrawn up- or downwards. The coil f may also be surrounded with granular material which cannot sinter. If desired the wholle apparatus may be arranged in a casing which can be evacuated or supplied with a protective gas. The coil f may be water-cooled and an extra thickness of refractory material may be arranged be. tween the crucible and the bottom of the coil.