US1555237A - Casting ingots - Google Patents

Description

CASTING INGO-TS Filed Aug. z5. 1921 a #-6 cf! Plz-g: 5- V 2 'zzwezvol Alca/11u50@ Patented Sept. 29, 1925.

ulNlTED STATES y A 1,555,237 PATENT oFFicE.

I ADOLF V'ERNER CARLSSN, OF XOLSVA, SWEDEN.

CASTING INcfoTs.- A

Application led August 25, 1921. Seria1 No. 495,151.

(GRANTED lUNDER THE rnovisrons or THE ACT on MARCH s, 1921, 41 STAT.v L., 131s.) E

To all lwhom t may concern:

Be it known that I, ADOLF VERNER CARLS- soN, av subject of the King of Sweden, residing at 'Kolsva, Sweden, have inventedl certain new and useful Improvements inor Relating to Casting Ingots (for which I have led application in Sweden, Nom-14, 1918, Patent No. 49,093, of April 21, 1921; England, November 13, 1919, Patent No. 135,207 Norway, November 25, 1919; Denmark, Nov. 12, 1919; arid Germany, November 27, 1919), of which the following is a specification.

When casting steel in a sandmould or an ingot mould, the composition and the temperature of the steel being such as to pro duce steel without blisters, a more or less deep funnel-shaped depression called the pipe will be formed in the upper port-ion of the ingot. The longerthe upper portion of the ingot can be kept in afluid state, the better can blow-holes which may appear in the ingotbe filled with molten metal from portions higher up andthe smaller will be the pipe. To retard `soliditication in the upper portion, a number of different methods are employed such as Y l (a) Building up or ramming the upper portion of ingot mould with ireproof material.

b) Pouring slag on the yfused steel.

- c) Supplying heat to the upper surface Vof the steel by ignited charcoal, thermite, or by electric heating.

Moreover, it is well known that carbon in some form `or other is used in combination with moulding material, thus for instance c'ores are filled with coke for venting said cores, compressed carbon is introduced in the walls of moulds for carburization or hardening of the steel cast, cores are made Yof lireclay or sand mixed withy powderedv graphite, and hollow cores have been made of a mixture, one element of which is combustible material for the purpose of obtaining combustion when the metal is cast.

By the present invention heat, is transferred to the upper part of the ingot mould thus retarding the solidiication of the dead head at this part and allowing molten metal to flowdown and preventformation of pipe underneath dead heads.

The present invention consists principally in ramming the walls of the feeding head .heat is evolved.

or the dead head with a material evolving heat under the iniuence ofthe castmetal and transferring heat to the dead head, said heat-evolving material being mixed with strengthening ingredients and, if desired, acting as a heat insulator and protected against n contact with the metal. Materials of this character are charcoal, coal and coke in the form of powdered or crushed to grains 'of suitable size and preferably mixed with clay and other ingredients required for obtaining the necessary rigidity of the mould when rammingit and drying the material. The vwalls of the dead head or feeding head are preferably coated with blacking, or they are given a thin lining of some flreproof paste to prevent the molten metal from coming into contact with the v.charcoal and thereby absorbing carbon. Preferably the feeding head made in thi way is only partly filled with metal, when casting. Abovethis body ofmetal there is then deposited a layer of a -material, such as charcoal, whichwill evolve heat under the influence of the cast meta1,-an :insulating stratum being preferably arrangedV in known manner between the molten metal and the charcoal, in order to prevent absorption of carbon. In accordance with this invention, the said insulating stratum may consist of molten slag or fused metal, the specific gravity of which is lower than that of the metal thereunder. The lslag cover can,

however, be omitted if the charcoal is ap-.

plied only after the solidification of the upper surface ofl the metal, an insulating stratum preventing absorption of carbon having thus been -formed already through the said solidifying action of the metal.

Any heat-evolving material can be a'dvantageously used, provided that the heat from the fused metal causes combustion of same, or -gives rise to a reaction whereby To illustrate the method, Figures 1 and 2 of the accompanying drawing show a/ runner opening or feeding head'in vertical section, the said'gures being illustrative of the novel features according to the invention, whereas Figure 3 isa vertical section of a-runner opening as heretofore known.

In Figure 1, a is the fused metal filling up the mold to .the level b-b. c is the sand mold, and d is 'the dead head in 'which is rammed the heat-evolvingpand heat-insulat-- solidified' stratum of the metal a1 itself, thev same having the position h, shown by dotted lines. e

Figure 2shows the appearance of the metal after solidication. The top surface has then sunk down evenly and assumes the position indicated by -the broken line b1 b, b1. The section shows a perfectly dense material, and the steel practically holds as much carbon in the upper part as in the lower part of the ingot.

Figure 3 shows the same metal cast in an ordinary sand mold, the ingot being shown immediately after casting and solidiication of same. In the lfused state the metal fills the mold up to the level b2 U2, that is to say as high up as in Figure 1.` This surface remains unchanged, that is to sayl the metal solidifies at the surface and remains at this level. The solidification also begins immediately from the walls of the feeding head and, in fact, from the walls of the entire vmould, while the central portions of the metal arestill molten. The solidification is continued' from the surface inwardly,the metal shrinks, and the metal lfrom the middle of the up er part sinks down, but when the metal at t e top surface and atthe walls of the feeding head has solidified, the metal cannot sink any further, this resulting in the formation of a `hollow-space or pipe, having an approximate vform and 'extension asshownatkinFigure3- g v The present invention/is,particularly applicable to steel castings, The dead heads in steel castings serve the same-purpose as the dead head (taken in the meanin of the metal cast in the feeding head) o ingots made with feeding heads, or the upper portion of ingots made without a feeding,y head, that is to say they vare employed as reser' `voirs for fused metal, introduced to fill hollow spaces appearing in the ingot during the solidification of'same. To this end the size of the dead .headsmust be considerable, as only a small portion of thev metal cast into the dead head is effective, filling the space cavities in the ingot, the greater part of the metal solidifying in the dead head around the walls. It is the cooling from the walls thathas to be prevented, this being brought about by making the wall so as to evolve heat, when coming in contact Awith the metal. The fused metal coming in contact with the walls, the carbon is caused to glow and evolves heat, thereby counteracting the radiation of heat from the metal and thus retarding the solidification. The ineffective part of the dead heads, which is rammed in the known manner and which can be used only as scrap iron, ordinarily amounts to more than half the weight of the finished steel casting, counted on the average of the whole production, the waste of Amaterial thus being considerable.

' Large dead heads have aV disadvantageous iniuence also on the quality of the' casting, that is to say, in so far as they are acting to the formation of cracks due to shrinking as well as to Ablow holes in the material.

The cracks are formed when on the cooling of the metal and the shrinking of it caused thereby, the strength of the material is insuiiicient to resist the stresses arising by the mold preventing the free shrinking of the metal. Blcw holes will arise in that part of the section, 'which is the last to solidify, when on the solidifying of the metal the volume is reduced and the space cavity forming cannot be iilled with fused metal from other parts. High temperature and a slow solidification and cooling act to produce cracks and blow holes. The solidi fication is acceler-ated, when the heat of the metal is quickly led off by-the wall of the mould and thus a low temperature of the mould wall is an advantage, conditions oth erwise remaining'thev same.

The steel havingbeen cast in the mould, it will be cooled by the cold walls of the but the more metal passing throu h is to say the temperature of the metal running from the ladle.

Steel castings being mostly 'cast by bottom gate, that is to say, by introducing the steel into the bottom partA of the mold, the steel filling the mould from the Vbottom upwards, the mater-ial, which fills the feeding heads, first passes through thev mould. Even if the pouring .is I ing also practised, when the metal reaches the feeding head, that is ,to say when the metal has just filled the mould proper, and the steel is then poured into the feedlng heads in order to obtain hotter metal in the latter, the pouring of the metal evidently 1s carried o'ut first into one and then into another feeding head, but as the feeding heads communicate through the mould, the steel obviously passes through the latter. Thus, the larger the volume of the feeding "heads relatively to the mould, the 'more metal will pass through the mould, the less will be the cooling of the metal and the greater the heating. of the Walls of the mould, the slower does the solidificationtake lace and the greater will be the tendency o cracking mterrupted, such procedure beL heads in the manner set forth with a material evolving heat bythe influence of the metal, the feeding heads are rendered more 'efficient and thus their volume can be reduced so as to counteract crackings and blow holes.

It is to be understood thatthe heat-evolving material, such as charcoal, added to the metal, must not come into contact with fused metal, this being prevented according to the present method by applying either molten slag or fused metal of a lower specie gravity than the metal itself, in which case the melting temperature of the slag or the applied metal is utilized,or, in known manner, there may be added a material such as borax, which affords. an insulating stratum and which is caused to glow or melt by the metal, in which case, however, part of the heat is taken from the metal. It is also possible to mix the heat-evolving material, such as carbon in some form or other, with suitable substances giving a slag of high fusibility, for instance lime and infusorlal earth or powdered glass, and to cover the surface with this mixture thus producing a molten, ,an insulating stratum between the carbon and the iron. It is, moreover, possi-v ble to let the top surface of the metal solidify and immediately thereafter lapply the charcoal. The point is to get the charcoal burning so as to evolve heat to the metal and simultaneously toN prevent; .the charcoal from coming in direct contact with the fused metal.

The present method is particularly applicable to steel, but may obviously be used also in casting iron and other metals.

wWhat' I claim as new and `desire to secure by Letters Patent of the United States is 1. A method of preventing the formation of pipe in ingots and castings and of reducing the dead heads thereof, and thus of counteracting cracks and blow holes in castings, consistlng in ramming the walls of the feeding head or the dead head with a material, such as coal breeze, evolving heat under the influence of the cast metal and `transferring heat to the dead head, said heat-evolving material being mixed with strengthening ingredients and acting.Y as a heat insulator.

2. A method according to claim 1, in which the heat-evolving material .is mixed lyvitth clay or the like for the purpose speci- 3. In a method according to claim 1 lacing an insulating stratum between the used. metal and the heat-evolving material in order to prevent absorption of thelatter.

4. In a method according to claim 1, allowingthe top surface of the metal `to solidify and thus form an insulating stratum above which a layer of heating material, as charcoal or the like, is placed and ignited in known manner. A

`5. A mould having the walls thereof rammed with a material, such as charcoalbreeze which is. heat-insulating and heatevolving under' the influence of the metal for the purposes specified. l

In testimony whereof I affix my signature.

ADOLFYVERNER CARLSSON.

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