GB332656A - Process of and apparatus for bright annealing metals - Google Patents

Abstract

332,656. Metallges. Akt.-Ges., Forster, H. von, and Lay, E. May 3, 1929. Resistance furnaces.-Apparatus for annealing metal sheets, wire and the like in a non-oxidizing atmosphere comprises an open-bottomed furnace 1 disposed above a charging and cooling chamber 7, the two chambers being relatively movable in a vertical direction so that they can be brought into close contact, a gas-tight joint being made by the engagement of a flange 7a on the upper end of the chamber 7 with the wall surrounding the opening in the bottom of the furnace. As shown, the chamber 7 is carried by a carriage 10 which is raised to press the chamber tightly against the furnace by a ram 11. A modified construction is described in which the chamber 7 is constituted by a pit, the furnace 1 being movably mounted so that it may be lowered on to and raised from the mouth of the pit. A non- oxidizing atmosphere is maintained in both chambers by supplying combustible gas, e.g. hydrogen, through pipes 4, 12, the chamber 7 being provided with a safety device 20 and with an outlet 13 to which a flame 14 of the escaping gas is maintained. The charge 16 is disposed upon a support 17 which is lowered into the chamber 7, the latter being closed by a cover 6 and run into position below the furnace. The cover 6 fits into a recess in a slide 5 which is withdrawn and a rod 3 connected at 18 with the support 17 which can thus be drawn upwardly into the furnace. On the termination of the heating operation the charge is lowered into the chamber 7, the rod 3 detachade, and the cover 6 replaced by returning the slide 5. The chamber 7 is then removed from the furnace and the charge allowed to cool, the cover 6 being tightened, if desired, by clamps 15. By employnig a series of chambers 7, the apparatus can be operated continuously. A modification is described in which the cover 6 is constituted by an upper plate of the charge support 17, the slide 5 being in this case omitted. The chamber 7 may be formed around its upper end with an annular sealing-trough to receive an additional bell-shaped cover and may also be provided with a water-jacket to accelerate the cooling, the supply of inert gas being taken from a gas-holder of the floating bell type which prevents fall of pressure and consequent infiltration of air. Fig. 5 shows a further construction suitable for use when impure coal or producer gas is used as the inert atmosphere, the charge 16 being contained in a thin-walled pot 32 between the cover 26 of which and a perforated plate 34 is disposed purifying material 33 such as cast-iron turnings. When the apparatus is used for annealing copper, the first part of the cooling operation is effected by supplying steam, the steam being replaced by the inert gas when the temperature approaches that of the condensation of steam.