US1865041A - Casting of ingots - Google Patents

Description

l 1932- c. A. PARSONS ET AL- CASTING OF INGOTS Filed March 21.. 1930 2 Sheets-Sheet 1 J1me 1932- c. A. PARSONS ET AL 1,865,041

CASTING 0F INGQTS Filed March 21, 1930 2 Sheets-Sheet 2 a i X i 1 4 rgj v Fatented dune 2, 1932 ALGEMNfiN PARSONS AND HUG-H MALCOLM DUNCAN, 0F NEWGASTLE-UN- TYNE, ENGLANTD; SAID DUNCAN ASfiIGNUR T0 SAID PARSONS; KATHARINE FARSQNS, VKNUEN'JL THQMPSON, AND FREDERICK G-URDUN HAY BEDFORDLEGAL REFRESEN'FA @F' d CHARLES ALGERNQN PARSONS, DECEASED GASTIENG @F INGOTS application filed March 21, lttdfierial No.

ti ent No, L67 1,253 dated the 29th day of May, 1928.

iii

til

till

It is an important feature of the process therein-described that the surface of the molten metal should be the last to solidify and forms of burner are described for providing the necessary top-heating.

Experience in practice has, however, shown that due to the cooling influence of the side walls of the mould the solidifying of the upper portions takes place round the periphery while the centre is still fluid, with a consequent distribution of segregates that involves cutting more of the ingot to waste than is desirable.

With a view to overcoming such difiiculties, the present invention consists in a process of casting steel ingots as indicated in which heat is applied in particular to the peripheral portions of the surface of the molten metal.

Referring to the accompan ing diagrammatic drawings which show ifierent forms of the invention by way of example Figure l showsa sectional elevation of a gas-heated mould,

Figure 2 being as regards its upper half a cross-section on the line 22 of Figure 1 and as regards its lower half a corresponding plan; I

Figure 3 shows a sectional elevat1on of a modified form of mould fitted with electrodes,

Figure a being as regards its upper half a cross-section on the line t4 of Figure 3 and as regards its lower half a corresponding lan. P en not otherwise indicated, the same reference symbols are used to denote corresponding parts in the diiferent figures.

ln carrying the invention into edect according to the form shown in Figures 1 and 2 and ap licable to the casting of a heavy steel ingot, t e mould in general is similar to that described in the specification above identi fied and comprises an open-topped circular body, a, of heat-resisting material converging 437,631, and in Great Britain May S, 1W9.

slightly in an upwarddirection and strengthenedby a steel casing, a and a removal coyer, b, w1th apertures, c, 0, asshown. The massive chill block, d, with protecting plate, 6, forms the bottom of the mould, w ile the molten metal is indicated at According to the present invention, after preheating the mould to ahigh temperature of the order of molten steel and pouring the metal into the mould so preheated to leave a free surface, hot gases are introduced through the more or less tangentially disposed ducts, It, It, so as to concentrate on the peripheral portions of the surface of the metal while heat is being continuously and simultaneously withdrawn from the molten metal by way of the base chill, d.

The hot gases thus disposed immediately above the molten surfaceserve both to heat the metal and also the upper part of the walls of the partly-filled mould with which latter the gases are held in contact by centrifugal force,

According to the modification of the invention shown in Figures 3 and t, electrodes c", z", are inserted as shown through certain of the cover apertures, 0, c, and are directed towards the peripheral parts of the surface of the metal'in the mould, immediately above which'theoperative arc-striking parts of the electrodes are disposed.

According to another modification of the invention, the surface of the molten metal and slag is covered with coke, coal or other combustible, jets of air, oxygen or a suitable mixture of gases being introduced laterally through the walls of the mould at the level of the coke or the like in a substantially horizontal and preferably tangential direction, as shown in Figures 1 and 2.

With any of the arrangements described above, the formation of segregates in the angle formed by the side walls and surface of the ingot by premature freezing due to cooling of the upper mould walls, is avoided or minimized, the isothermals being thus maintained more truly horizontal until solidification is complete; as a result the upper surface. of the ingot is substantially plane with the segregates more closely adjacent thereto so lit that a smaller quantity of metal is cut to waste.

So long as the peripheral parts of the surface are maintained fluid by heat concentrated thereon in accordance with this invention, it is found that in general the fluidity of the centre part is likewise maintained without further addition of heat, but if desired, heat may also be supplied to the centre of the surface in special cases'in order to assist in securing horizontal isothermals.

The details of the processes above described may be varied without exceeding the scope of the invention.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is 1. A process of casting metal ingots, which comprises preheating the refractory walls of an open-topped mould to a high temperature, pouring the metal into said preheated mould, withdrawing heat from said molten metal substantially wholly from the bottom thereof, and from points disposed above the free surface of said molten metal simultaneously and continuouslyconcentrating heat directly on a I narrow peripheral strip of the superficial area of said molten metal, thereby to prevent premature top freezing due to cooling of the up)- per mould walls and so to maintain the su stantial horizontality of the isothermals throu hout the cooling process.

2. process of castmg metal ingots as claimed in claim 1, in which said mould is only partly filled by said metal poured thereinto so that the mould walls pro'ect above the surface of said metal so poure and said heat is concentrated from above on a narrow peripheral strip of the superficial area of said molten metal by hot gases moving in a substantially ripheral direction and disposed directly a ove the surface of said moltenv metal, thereby simultaneously heating both acting on said hot said mould walls projecting above the surface the to peripheral strip of said molten metal and a so heating byhelp of centrifugal force gases, the inner surface of of said molten metal.

3. A process of casting metal ingots as claimed in claim 1, in which said mould is only partly filled by said metal poured thereinto, the cross-sectional form of the mould walls immediately above said free surface of molten metal being inwardly concavely curved, and said heat is concentrated from above on a narrow peripheral annulus of the surface of said molten metal by hot gases moving tangentially to said concavely-curved walls and directly above the surface of said molten metal, thereby simultaneously heating boththe to peripheral strip of said molten metal and t e inner surface of said concavely-curved walls.

4. A rocess of casting metal ingots as claimed in claiml, in which said heat is conative centrated from above on a narrow peripheral strip of the superficial area of said molten metal by burning fuel floating on said molten metal within the area of said narrow peripheral strip.

5. A process of casting metal ingots as claimed in claim 1, in which said heat is concentrated from above on said narrow peripheral strip of the surface of the molten metal by striking electric arcs between elemental areas ofsaid eripheral strip and the operarts of electrodes disposed immediately t ereabove.

In testimony whereof we have signed our names to this specification.

CHARLES ALGERNON PARSONS. HUGH MALCOLM DUNCAN.

Images