GB785824A - Process and device for coating ingot and other moulds - Google Patents

Abstract

785,824. Casting-processes. DAUSSAN, H. J. Oct. 5, 1954 [Oct. 6, 1953; Sept. 6, 1954], No. 28617/54. Class 83 (1). In a method of covering the inner wall of an ingot or like mould with a protective coating, a charge of a material which is either in the form of finely-divided particles or is capable of being separated in fine particles or globules, is disposed in the mould, and dispersed into the atmosphere of the mould in the form of a cloud of particles or pasty or liquid globules under the action of the pouring jet and the hot gases accompanying said jet. The charge 5 is contained in a cup 2 in a bottom-pour-mould 1, the bottom of the cup having a portion which may be perforated easily by the pouring jet 3. The hot gases accompanying the jet project the powder or globules of the charge upwardly. The remainder of the cup rapidly burns away and the rest of the charge spreads out over the top of the molten metal, gases continuing to blow on it to eventually spread the charge over the entire height of the mould wall. In a modification the charge is contained in a package, e.g. of paper, cardboard, &c., for easy handling and positioning. The package is sealed by inflammable adhesive bands which rapidly burn away to allow the package to open when pouring commences. In a further modification, Fig. 7, the charge 5 is contained in a cup 26 having projections 28 at the bottom and made of pressed steel, cast iron, &c. which is progressively melted by, and mixed in, the molten metal. The cup may be closed by a readilydestructible cover 29 of paper or cellulose-base material. The projections 28 retard the outward flow of the molten metal so that the wave of metal does not travel up the walls of the mould where a coating has already been formed. In a further modification, Fig. 8, the charge 5 is in a package 33 placed in a steel tray 30 in the bottom of which is a steel plate 31 with pressedup projections 32. In a further modification, several packaged charges are superimposed in the bottom of the mould, to obtain a coating comprising several superimposed layers. Mould materials. The charge may comprise carbonaceous materials in any form such as graphite, cellulose, sawdust, charcoal, natural or synthetic resins or dextrin,.powdered with grain sizes varying from 0.15-0.05 mm. to 0.5- 0.2 mm. diameter, depending upon the respective specific weights. In an example the charge is, by percentages, powdered graphite 40-60; charcoal 40-20; remainder sodium carbonate. Further, the charge may be such as to give, by combustion, lamp-black, which may be mixed with other dust particles, e.g. carbon, salin, bituminous or resinous materials. In particular 60-80 per cent soft coal as soft or bituminous lignite or both, remainder fir or pine sawdust, may be used. A little caustic soda may be added to transform residue ashes into alkaline salts to form a fusible slag. To the foregoing examples may be added 5-20 per cent of one or more of the following:-tar; coaltar-pitch; peat; colophony; resin; bitumen or dextrin. Other examples are given of mixtures containing water in the form of waterof-crystallization, constitution, or condensation, or added water, one example containing carbonaceous material and-sodium carbonate, silicate, or tetraborate or mixtures thereof, and a further example containing powdered-graphite or mineral coal, charcoal in powder form or lampblack, and sodium carbonate. Specifications 754,573 and 785,823 are referred to.