US2119321A - Apparatus for casting metal ingots - Google Patents

Description

y 1938. I A. M. ERICI-IISEN 2,119,321

APPARATUS FOR CASTING METAL INGOTS Filed Jan. 27, 1957 5 Sheets-Sheet 1 FigJ. h

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APPARATUS FOR CASTING METAL INGOTS Filed Jan. 2'7, 1957 3 Sheets-Sheet 3 t 1 49 .fui ML v t 01:67am

Patented May 31, 1938- UNITED STATES PATENT OFFlCE 2,119,321 j APPARATUS roa CASTING METAL ING'oTs Abraham Martinius Erichsen, Teltow, near Ber- .lin, Germany In Germany February 23, 1934 Application January.2'l, 1937, Serial No. 122,531

a claims. ((132-177) is again a tendency to form blow-holes which can. be recognized by the depression which is generally formed in the middle. This depression, which varies in accordance with the thickness of 15 the metal billet to be cast, is a disadvantage when I the billet is rolled down. Further, when the billet is being rolled down, it is also found that the structure of the material in the middle of the casting is not so good as at the edges. Casting 20 in open horizontal moulds has therefore been made little use of up to the present'time in spite of its economic advantages and the greater ease with which it can be carried out.

Now the object of the present invention is to 25 obviate the dimculties which arise when casting in open horizontal moulds and to obtain cast slabs or billets which are throughout of as uniform structure as possible and of which the upper surface is as plane as possible. This result is 30 obtained, in accordance with the invention, by regulating, during the solidification process, the temperature of the cast billet, one of thebroader surfaces of which isexposed' on top, in such a manner that the middle of the slab or billet 35 solidifies at approximately the same rate as the edges. This can be done by suitably cooling the horizontal mould the upper longitudinal surface of which is open or by retarding the emission of heat at the edges or sides of the open mould. Ob- 40 viously, both expedients, namely cooling and retarding the emission of heat, can be employed simultaneously. In any case the cast billet, the upper exposed surface of which is the surface on which the rolls act, solidifies from the centre 45 outwardly throughout its entire mass in as uniform a manner as possible. I

It is true that horizontal moulds which. are open on top are known. With such moulds attempts have been made to obtain as uniform a 5 solidification of the metal as possible by arching the inside ofthe'bottom of the mould in order .to accelerate solidification of the centre of the 'casting by the withdrawal of heat owing tothe accumulation of the material of the mould at 55 this place. By this means, however, cast billets of irregular cross-section are obtained which are thinner in the middle where, for technical reasonsconnected with the rolling process, greater thickness is desirable. On the other hand an appreciable acceleration of the solidification either cannot be obtained by increasing thev thickness of the bottom of the mouldor can be obtained only if the cross-section of the billet is correspondingly less owing to the thickening of the bottom of the mould and the cooling is therefore more rapid at this place. It must also be added that solidification at the ends of the oblong mould is not retarded by arching the bottom of the mould.

0n the other hand, when casting in closed moulds, it is known to cool the bottom of the mould in various ways during the solidification of the cast metal. Thus, for example, a process is known in which, after the metal has been cast, the mould is closed by a cooling lid and then inverted, so that the lid acts as a cooled bottom for the closed mould. A process is also known in which different kinds of metal are cast successively in layers in the closed mould, in which case the bottom of the mould is cooled for the purpose of cooling the lower layer of metal as rapidly as possible. In these known processes not only are closed moulds usually employed but generally also vertical moulds. i a

The cooling of horizontal open moulds can be effected by conducting through the bottom of the mould? a cooling medium which preferably cools the middle of the mould. In some cases additional cooling from above, especially with thick castings, can be undertaken. The sides of the open mouldv can be made of a material of poor heat conductivity, for example chamotte or an iron-nickel alloy, in order to accumulate heat at these places. By this means it is possible to regulate the cooling of the casting in such a way that the middle and edges of the cast billet solidify approximately simultaneously from bottom to top, andin some cases even in such a way that solidification occurs sooner" in the middle 1 than at the edges, without blow-holes being produced or liquation occurring.

The bottom plate of the mould alsois preferably made of different materials, for example of copper in the centre and of a-poor heat-conducting material at the edges.

For' assisting the eflfect which it is desred to obtain, namely as uniform a rate of solidification as possible throughoutthe casting in the open mould, the" surface of the casting can also be cooled wholly or partly from above, for example 55 by sprinkling it, by means of-compressed air and so forth, or the open mould may be covered at the edges by a plate which is cut away, in the middle and is arranged at some distance above the open mould. This plate allows the heat to -be radiated away freelyin the middle while the dispersion of heat. at the sides by radiation to the air is retarded. The same effect can also be obtained by a partial heating of the surface, for example 'atthe edges, by means of gas, steam, air and so forth.

In order to promote an equalization of heat in all layers of the cast block, it may be advantageous to keep the metal in motion during solidification by slowly tilting the open mould backwards and forwards after the metal has been cast. This flow of the metal has the result that crystal formation, which takes place fromthe bottom upwardly, is eflectively suppressed whereby the density and the capacity of the material for being rolled is increased as is well known. The flowing movement of the metal also enables the solidification process to be observed in all parts and tobe regulated. For obtaining a flowing movement of the metal the mould is preferably mounted in' such a way that it can be tilted or oscillated about an axis. Preferably, means for limiting the amplitude of the swinging movements, which means can be removed for the purpose of completely inverting the mould, is provided.

Various constructional embodiments of apparatus for carrying out the method of casting according to the invention and forms of castings which can be produced by means of the method are illustrated by way of example in the accompanying drawings, in which Fig. 1 is a vertical section through "'ohe form of theapparatus, and

Fig. 2 an end elevation of the same. i";

Fig. 3 is an apparatus with a double mould in vertical section.

Fig. 4 is a vertical section on the line IV-IV of Fig. 3. a

Fig. 5 is a section through a mould in hich, in addition to the bottom cooling, the op is cooled.

Fig. 6 is a perspective view of thesame mould on a smaller scale.

' Fig. 7 is a plan view and Fig.- 7a a vertical section of a mould which is subdivided into compartments.

Fig-8 is a plan view and Fig. 8a is a vertical section of another mould which is subdivided into compartments.

Fig. 9 shows a vertical section of one form of casting which can be obtained by means of the process according to the invention.

Referring to the drawings, the horizontal mould which is illustrated in Figs. 1 and 2, and of which the upper longitudinal surface is open, consists essentially of the bottom plate a and the side frame 12. The bottom plate a can be made of a material havinggood heat conductivity, for exretard the dispersion of heat atthese places. The bottom plate is preferably made in several parts, the middle being made of material of better conductivity or the outer parts of a material of poorer conductivity.

The bottom plate is mounted on a support 0 which is carried in bearings, for example, on

standards d. The upper surface of the bottom can be hollowed out in known manner as indicated by dotted lines, in order that the casting may be thicker in the middle as is often desirable when it is to be rolled later. The support 0 is hollow at f in order that a cooling liquid or other cooling medium may be made to sweep over the bottom of the mould. As shown in the drawings easily, a tilting device which is operated by a hand wheel, for example, by means of a worm and worm wheel, is provided. Thistilting device can When the frame 0 is rotatable, as in the be used at thesame time for swinging the mould backwards and forwards slowly during solidification of the metal, and also for enabling the molten metal to be poured in at one corner when the mould is in a tilted position, so as to be able to cover the bottom quickly with metal by tilting the mould into a horizontal position. In this way it is possible to cover the bottom quickly with metal by first pouring in the metal, when the mould is in a tilted position, into the depressed portion along the edg'e, and then quickly tilting the mould, so that a full stream of metal flows over the bottom, whereby the lower surface becomes as smooth as possible. In Fig. 2 the mould is shown in dotted lines in the completely inverted position and also in the position which it takes up when it is oscillated'during solidification of the metal. The latter position can be limited by means of a guide-slot i and pin is. In order to be able completely to invert the mould it is only necessary to withdraw the pin it.

The side frame I) of the mould can be fixed to thebottom plate a in known manner by means of screws so that it can be changed in order to be able to cast ingots of different sizes and shapes.

The frame may be of any suitable shape and may depart from the rectangular shape illustrated, in order that when the billets are rolled out there may be no tails which afterwards have to be removed and constitute waste: In order to avoid this it is an advantage to construct the side walls of the frame wholly or partly in such a way that they extend somewhat inwardly at the edges or ,are set back in the middle, so that, when the billet lsrolled out, the ends are approximately straight or even, and no projectlngt tails" which cause waste are formed. For this purpose the walls of the frame can be concave, angular or otherwise hollowed out on the inside, so that a casting having a corresponding shape is obtained.

. In all the fastenings, particularly in the mounting of the bottom plate a on the support 0 suitable Aallowance must be made for the free expansion of the parts under the influence of heat.

. The tendency of the bottom plate a to warp and bend upwards, owing to the transfer of heat on one side from the casting and to the cooling on the other side, is prevented by the fastening screws m. For the same purpose, namely to prevent warplng and distortiom'the bottom plate a can rest on the partition 0, which is then provided with small projections which support the bottom plate without preventing the cooling medium from flowing over it. Several partitions or ribs may also be provided for-the'same purpose. I

In the form of construction according to Figs. 3 and 4 a double mould is used. This mould is of similar construction to that of the simple mould shown in Figs. 1 and 2 and can be tilted by means two moulds are cooled in the middle by the hollow space 1 of the support 0 through which space a cooling medium flows. The partition or rib e ends at the top and bottom at a slight distance away from the bottom plates, or it is provided with extensions on which the latter are supported, so that the cooling medium must flow along the bottom of the mould. The bottom plates (1, a can again be made of a material of good heat conductivity and the walls b of a material of poor heat conductivity. The mould also may be provided with a cover plate T having an opening at the middle thereof to obtain a differential radiation efiect of the heat at the center and the sides of the mould as' described above. This cover plate serves to reduce the radiation from the side portions of the mould and promotes the cooling of the middle of the top surface thereof.

The moulds may also be provided with external cooling, which has no effect on the cast metal and the object of which is only to cool the mould down again quickly after casting has taken place. For this purpose the supportc can be provided on the outside with upstanding walls 0 in order to form chambers for the reception of a cooling liquid or the like. The cooling liquid is preferably admitted to these chambers only after complete or partial solidification of the casting in the mould.

In the form of construction according to Figs. 5 and 6, the mould which is open on top is additionally provided with a cooling device on top, which is desirable particularly for thick castings, in order that solidification of the core or middle part of the casting may be accelerated throughout its entire depth. The upper hollow cooling bar 12, which may be fixed or removable, is provided with an inlet pipe and an outlet pipe for the cooling medium, and may extend across the entire length of the mould which otherwise is open on top. (See Fig. 6.) The mould illustrated is made in three parts and consists of the side frame I), the bottom a and the lower cooling chamber 1 having an inlet-and outlet for the cooling medium. The lines and arrows in Fig. 5 indicate how, owing to the cooling above and below, the central core of the casting solidifies first and the still liquid metal flows in the direction of the arrows towards the middle, so that the final solid block is thicker in the middle as illustrated in Fig. 5, or is at any rate level on top, instead of being sunken in the middle as hithert usual.

The shape and dimensions of the upper bar 0 may of course be as desired.

Further, a similar arrangement for cooling the top of the casting can also be employed for moulds which, as in Figs. 1-4, are carried by a rotatable or swingable frame.

In all forms of bonstmction the moulds can with one casting frame.

also be provided with a cover by which they can be closed, in order to allow the casting to cool down in an inverted has occurred.

' In a similar manner to that previously deposition after solidification scribed, stationary, rotatable, or tiltable multiple casting frames which contain .more than two moulds can be constructed, in order to beable to make a larger number of castings with the same apparatus. Thus, for example, the moulds themselves can be subdivided in order to be able to cast two or more metal ingots simultaneously each illustrate in cross section and plan two forms of construction of a casting frame having four moulds or compartments. The ribs n which divide up the mould can be fitted on the bottom a of the mould either so that they are fixed or removable (Fig. 7) or they may be fitted on side frames which can be inserted from the top or are made integral with the mould (Fig. 8). Instead of dividing the mould into two or more separate compartments, two ormore moulds can be arranged one beside another on a common supporting or rotatable frame.

The method and apparatus described can be used for all metals, such as iron and non-ferrous metal. and in particular for casting metal alloys, for example brass.

Owing to the more rapid cooling of the middle of the cast ingot as compared with the edges and sides which remain liquid longer, the formation Figs. 7, 7a and 8, 8a.

of a depression in the middle of the casting is prevented, By virtue of the present invention billets or ingots are produced having an upper surface which is substantially plane. Owing to the plane upper surface of the ingot not only is its suitability for rolling improved, but the further advantage is presented that the skin due to casting can be quite uniformly removed by planing the casting, so that wastage from the milling and planing process is no greater than that from castings which have been cast in vertical moulds. 0n the other hand waste due to the presence of blowholes, such as occurs to a considerable extent with castings which have been cast in vertical moulds, does not..occur at all, whereby considerable economy results as compared with casting in vertical moulds.

rolling since the rolls do not compress the thicker blocks uniformly. In order to facilitate the rolling at the first pass or also at the following Pass, the ingots or billets can be cast in wedge-like shape as illustrated in Fig. 9, so that the end t is thicker than the other end u. The thinner end is then first introduced between the rolls. To

make billets of this nature the mould is merely displaced slightly out of the horizontal. The mould may also be tapered slightly at one end while being otherwise plane.

The characteristic feature of the new metal ingots or billets in any case is that the upper side which is exposed to the air in the horizontal mould, and may be horizontal or inclined, is plane or slightly raised inthe middle, and is thereby distinguished from the known ingots cast in open moulds or trays the upper surface of which is-always somewhat concave.

It is immaterial whether the metal to be cast has a strong or less strong tendency to form pipes cooling down during solidification in generaltakes place slowly in spite of the local cooling, which appears to be favourable for the crystal formation in the case of most metals. Since the castings are visible during all stages of solidification, the solidificationprocess can be regulated by applying or increasing the cooling so that a surface of the desired form can be obtained in all cases and with all kinds of metals and alloys.

The fact that, even on the flrst pass between the rolls, the billets, owing to their shape, are subjected to at least the same pressure in the middle as at the sides is also an advantage. Billets having a depression in the middle are of course subjected to less pressure in the middle,

so that extension without corresponding pressure occurs which may lead to fracture of the rolled plates or sheets.

What I claim is:- 1. A horizontal open top mould for casting flat ingots, composed of a bottom, side walls of low heat conductivity, cooling means placed at the middle of the otherwise open top of the mould ,i'ace of the cast mass to cool the same at the middle; means forming a cavity to hold a. cooling medium in contact with the middle portion of said bottom, and means for conveying a fluid cooling medium to and from said cavity.

3. A horizontal mould for casting flat ingots, composed of a bottom, sides of low heat conductivity, a; cover plate of heat insulating material having an opening in the middle and covering only the side portions of the top of the cast mass to reduce the radiation from said side portions and to promote the cooling of the middle of the top surface of the cast mass, and means forming a cavity to hold a. cooling medium in contact with said bottom. a

4. A horizontal mould for casting flat ingots,-

composed of a bottom, sides of low heat conductivity, a cover plate of heat insulating material having an opening in the middle and covering only the side portions of the top of the cast mass to reduce the radiation from said side portions and to promote the cooling of the middle of the top surface of the cast mass, and means forming a cavity to hold a cooling medium in con- .tact with the middle portion of said bottom.

tact with said bottom, and means for conveying a fluid cooling medium to and from said cavity.

6. A horizontal mould for casting flat ingots, composed of a bottom, sides of low heat conductivity, a' cover plate of heat insulating material having an opening in the middle and covering only the side portions of the top of the cast mass to reduce the radiation from said side portions and to promote the cooling of the middle of the top surface of the cast mass, .means forming a cavity to hold a cooling medium in contact with the middle portion of said bottom, and means for conveying afluid cooling medium to and from said cavity.

'7. A horizontal open top mould for casting flat ingots, composed of a bottom, side walls of low heat conductivity, means forming a cavity to hold a cooling medium in contact with said bottom, whereby the uncovered cast mass is cooled from the bottom as it solidifies, and means for supporting the mold with its bottom in a slightly inclined position in order to form a wedge-shaped ingot.

8. A horizontal open top mould for casting flat ingots, comprising bottom composed of a central portion'of high heat conductivity and side portions of lower heat conductivity, side walls of low heat conductivity, cooling means placed at the middle of the otherwise open part of the mold in position to make contact with the top surface of the cast mass to cool the same at the middle, and means forming a cavity for holding a cooling medium in contact with said bottom.

ABRAHAM MARTINIUS ERICHSEN.

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