US1888913A - Mold for casting metals and metal alloys - Google Patents

Description

Nov. 22, 1932. l A. M. ERlcHsEN om Fok CASTING METALS AND METAL ALLOYS Filed OQ. 9. 1930 2 Sheets-Sheet 1 n mui Nov. 22, 1932. A. M. ERlcl-lsr-:N

MOLD FOR CASTING METALS AND METAL ALLOYS Filed Oct. 9. 1950 2 Sheets-Sheet 2 f INVENTO R raaJ/Z FM.

Patented Nov. '22, 1932 UNITED STATES PATENT OFFICE ABRAHAI MARTIN IUS ERICHSEN, OF TELTOW NEAR BERLIN, GERMANY HOLD FOB CASTING METALS AND METAL ALLOYS Application led October 9, 1930, Serial No.

When iron, other metals or metal alloys are cast, more particularly in plates or-ingots, a zone is formed where the formation of fissures is more predominant; and also in cases .6-,where impuritles are present or there is a pluralit of metals present to form an alloy liquatlon or the separation of certain components occurs in this zone. The zone is usually centrall disposed and is found to remain in :9. liqui state for a longer period than the other parts of the casting. This zone causes lack of homo eneity.both in compositiorrand strength, an consequently many attempts have been made to eliminate it. For examl5 ;ple, one of the side walls has been pressed inlwards against the casting during solidifcationv with a view to extruding the metal contained in this zone out of the main body of the casting, and at the same time to force metal into those parts of the mold which remain unoccupied.

Whereas in the known methods, pressure has been applied to the molten metal through rigid but movable parts of the mold, the

2fpresent invention comprises a mold for castlng metals and metal alloys, having a wall or walls which under the action of stresses, due to temperature changes, occurring in the material forming the walls, or of external pres- 439;Sure can, by distortion or by resumption of normal shape after a prior distortion, exert pressure on metal forming a casting prior to and/ or during the solidifcation thereof.

vBy this means, the unwanted zone is re- -ffmoved and any fissures tending to form are filled by an upward flow of molten metal under pressure. Y

Each o erative wall of the mold may either be istorted so that 'it will have an inqbwardly cup-shaped configuration, or it may be first distorted so that 1t has an outwardly cup-shaped configuration and subsequently forced inwardly to form a flat surface. The latter method is preferable when a casting uhavin the flattest possible outer surfaces is By adjustment of the pressure and the total quantity of molten metal poured into the mold, a greater or less quantity of metal 5Lcan be forced out so that when solidification 487,591, and inl Germany February 28, A1929.

is complete, the casting is entirely' free of fissures, and at the same time the inferior metal, contained in the unwanted zone is no longer present in the main body of the-castmg.

It is preferable to apply the pressure while the metal to form the casting is solidifying, but it may be applied prior to, or prior to and during the process of solidifcation. As the whole of the casting, while solidifying'is still 60 soft and malleable and the central portion remains molten, relatively small pressures on the Wall of the mold sufiice to express the molten metal from the centre. It has been found, particularly with copper alloys and other metals which liquefy readily, that the A stresses resulting from contraction and expansion with temperature changes and pro-` duced in the casting itself are suflicient, if the thickness and conductivity and expan- -sibn coefficients of the cooling plates be suitably to extrude the fiuid core from the cast-` ing.

It is common practice when casting iron and steel ingots, to link several moulds to- 76 i gether by channels, so that when the metal is poured into one mould, it rises simultaneously\ in the others. When the mould is filled gradually from the bottom upwardsin this manner, the lower end of the casting remains warm and mouldable for a longer period than if the fluid metal is vpoured in at the top, andv consequently-the fluid core can be squeezed out downwardly or upwardly or towards both ends of the casting.

In order to obtain pressure effects by temperature change alone, thewalls of the mould vmay comprise two or more plates of metals of which the coeflicients of expans' n diil'er, the plates being joined together in any suitable manner.

The advantages of the invention do not reside solely in the elimination of fissures and/ liquation. Equally important is the fact that by the extrusion of metal in the manner described, the formation of large crystals is avoided, growth of the crystals being pre-` vented or retarded. In ingot cast according t0 the invention has markedly fine crystals; 100

a fact of considerable importance in the further treatment of the metal.

The pressure and subsequent movement affects the crystals in the half-solidified casting similarly to rolling or pressing. Radiating fissures which are normally produced in castings during solidification are also completely eliminated by the use of a mould according to the invention.

It is common practice when casting copper alloys and the like, to employ cold or chilled moulds. Such moulds may be formed in accordance with the present invention by constructing the cold plates in the form of diaphragms and applying pressure to the centres thereof.

It is sullicient if the pressure be applied on one side of the casting only, that is to say, if only one of the side platesibe cupped and movably mounted, but both side walls of the mould ma be mounted flexibly and the pressure may e a plied on both sides.

It is prefera le to make the mould from a metal of low heat conductivity such as nickel steel, Erical, Invar and the like, as then the rate of solidification is reduced and the advantageous results of the pressure on the casting increased.

The extruded metal forms a ridge or protuberance on the top 'of the plate or ingot, or the quantity of metal may be suflicient for it to flow over the top of themould.

Several embodiments of the invention are, by way of example, illustrated diagrammatically in the accompanying drawings.

Figure 1 is a longitudinal section of a mould for casting plates provided with liquid cooling, in which two walls can be pressed inwardly.

Figure 2 is a lon itudinal section of a mould for casting p ates provided with a flexible wall on one side only.

Figure 3 is a section of part of a cold mould with cold plates secured as diaphragms and provided with packing pieces.

Fi re 4 is a section of a cold mould-provide with cold plates, each comprising two connected plates of different metals.

In the mould for casting plates as shown' in Figure 1, which is employed more particularly for casting plates of copper, nickel, aluminum and the like, as well as their alloys, such as, brass, nickel sil-ver and the like, the plates g are secured in the mould h as diaphragms, so that a small distortion or cupping is possible both outwardly towards the water chamber z' and inwardly into the castngchamber c. c is a position (drawn in dotted lines) the -platesg ma occupy before the metal is poured in, and is the position they may occupy when pressure is being exerted during the solidification of the casting k. The plates g may be bent from the outwardly cu ped position c or from the vertical position shown in full lines into the inwardly cupped position d, or they may be previously cupped outwardly to such an extent that suilicient pressure will be obtained by Abending them back to the vertical position in order to obtain a casting having flat surfaces.-

The fissure or lfquation zone which obtains in the casting c under normal conditions is denoted by b; according to the invention this is removed, forcing it right out in the direction indicated by the arrow m by pressure applied on the plates g, so that finally the metal contained in this zone occupies a position at the head of the casting lc and may form there a protuberance a, the size of which will depend on the pressure applied and the excess of molten metal that was added during the pouring.

Mechanism for exerting the required pressure comprises screws e co-operating with in tcrnally threaded nuts f which are fixed to the platesg so that by rotating the screws e, the plates g may be moved inwardly or outwardly to occupy any desired position. As an alternative to this arrangement the screws e might be rotatably mounted in a hinged device secured to the plates g and the nuts f provided in some other position along the screw, for example, on the main casing h.

o, p are the watei` supply and discharge pipes for the cold Water chamber z'.

In the construction according to Figure 2, the mold h is provided with a movably held resilient plate g, which, Without outside pressure, bends towards the casting when heated, So that during casting the zone b is forced out in an upwardly direction. A protuberance a will likewise be formed in this case.

A screw n forms an adjustable stop to limit the outward movement of the plate g, which can thus be adjustedv in accordance with its initial stress and which generally presses tightly against the stop. A number of screws n, as shown in dotted lines in Figure 2, or other adjustable or fixed stops may -be -employed.

In order thatthe walls of the mold may be cupped outwardly beforehand so that they form a flat surface when pressed in, they may be mounted as diaphragms on two separate packing pieces y, z, as shown in Figurev 3, the outer piece y being of a harder mate-- rial than the inner piece a, which is made of a soft or resilient material such as rubber or is rendered resilient by an insertion ofrubber or the like in suitable manner, for which purpose it may comprise, for example,

a thin walled metal tube with a rubber core.

By tightening the screws r, several of whichare situated along the periphery of the plates g, the plates will be cupped towards the water-side z', as the outer harder packing piece g/"does not,L give to the same extent as the inner packing'piece zy By this means,

the cooling plates g bear tightly against the ribbed body u of the mold, but lcan bend in both directions like a diaphragm without failure of the packing. As the cold plates bend in and out, the soft inner piece z will produce a ti ht joint, while the hard outer piece y provi es counter pressure, so that the cold plates are stressed inthe desired manner towards the water chamber i.

Figure 4 illustrates a cold mould with cold plates, each comprising two plates fv, w, secured to ether in any suitable manner. y

The col lates are shown cup ed towards the water c amber i; they may e distorted either as a result of prior treatment which tends to give them a cupped configuration normally, or by the action of packing pieces and screws, as described with reference to Figure 3. A further device is shown in the drawin It comprises a screw s which is screwe a certain wa into the plate w and then forced outward y, dragging the plate with-it, by means of a wedge t. The outward movement of the plates v, w, however produced, is limited by stops u. When metal 1s poured with the mould, the plates v being closer than the plates fw will absorb more heat and so expand a greater extent, thus tending to straighten the double plates o, w. an effect ywhich will be greatly enhanced if the plates 'v and w are constructed of metals having different coeicients of expansion. The inward straightening movement of the plates will be prevented by the screw .s bearlng against the wedge t. When this is loosened, however, the plates will bend inwardly and exert considerable force against the side of the casting k and the beneficial results described above will thus be obtained. In order to limit the amount of distortion, the wedge t is provided with adjustable pins or stops so that its movement is limited with consequent limitation of the distortion of the plates in either direction. As the screw 8 is adjustable, the limit to the distortion can be adjusted as desired.

The purpose of the apparatus shown in Figure 4 is to enable a hlgh pressure acting over a limited distance to be suddenly applied, that is, consequent of a single blow,

with a hammer.

It is to be understood that the screw and other devices illustrated inthe drawings are shown by way of example only and if desired they may be` replaced b levers, hydraulic pressure, contracting ings, wedges of any other device capable of exerting mechanical pressure on the outside of the mould plates. Thetension devices ma similarlybe re laced, a still further examp e comprising a istance piece of a fusible metal which will melt during casting and so release the plates.

The invention can be employed for casting and adapted to the special requirements of all/ metals and metal alloys in cooled-or uncooled metal moulds. It ma be employed for casting iron, steel an the like but is more particularly adapted for casting non-ferrous metals, precious metals and their alloys, such as co per, nickel, German silver brass and the li e. It will be understood that `one or more walls of the mould may be provided as pressure walls with or without cooling.

The walls of the mould may preferably consist partly or wholly of metals that have a -low heat conductivity coeflicient but such a coefficient of expansion that the resulting effect will be to increase the pressure actin on the castin Suitable examples of suc metals are a loys containin nickel and chromium and having a coe cient of heat conductivity less than 0.10 calories r centimetre second, for example, Erical, nvar, or the like.

I claim:

1. In a mold for casting metals and metallic alloys', a wall made of material subject to distortion when exposed to differences in temperature; a support for said wall, rigidly connected to the ends of the latter for maintaining said ends in fixed relation and leavin the intermediate portion of the wall free to come distorted upon pouring, and exert a pressure on the mass poured in the mold.

2. In a mold for casting metals and metallic alloys, a wall made of material subject to distortion when exposed to differences in temperature; a support for said wall, rigidly connected to the ends of the. latter for maintaining said ends in fixed rel-ation and leaving the intermediate portion of said wall free to become distorted upon pouring, and exert a pressure on the mass poured in the mold; and means carried by said support and cooperating with the intermediate portion of the wall to urge the same in its pressure exerting distortlon.

3. In a mold for castin metals and metallic alloys, a Awall made o a material subject to distortion when exposed to differences in temperature; a support for said wall, rigidly connected to the ends of the latter for maintaining said ends in fixed relation and leaving the intermediate portion of the wall free to become distorted upon pouring, and exert a pressure on the mass poured in the mold; and means associated with said sup ort and acting on the intermediate portion o the wall to limit the distortion thereof.

4. In a mold for casting metals and metallie alloys, a wall made of a material subject to distortion when exposed to differences in temperature; a support for said wall, rigidly connected to the ends of the latter for maintaining said ends in fixed relation and leaving the intermediate portion of the wall free to become distorted upon pouring, and exert a pressure on the mass ured inthe mold; and, a packing between t e wall and its point of attachment to the support.

5. In a mold for casting metals and metallic alloys, a wall made of a material subject to distortion when exposed to differences in temperature; a support for said wall, rigidly connected to the ends of the latter for maintaining said ends in fixed relation and leaving the intermediate portion of the wall free to become distorted upon pouring, and exert a pressure on the mass poured in the mold; and, a packing between the wall and its point of attachment to the support, said packing consisting of an inner and outer member, the inner member being softer than the outer member. 4

6. In a mold for casting metals and metallic alloys, a wall made of a material subject to distortion when exposed to differences in temperature; said wall consisting of a plurality of adjacent plates each being acted upon differently by the change in temperature; a support for said wall, rigidly connected to the ends of the latter for maintaining said ends in fixed relation and leaving the intermediate portion of the wall free to become distorted upon pouring, and exert a pressure on the mass poured in the mold.

7. In a mold for casting metals and metallic alloys, a wall made of a material subject to distortion when exposed to differences in temperature; a support for said wall, rigidly connected to the ends of the latter for maintaining said ends in fixed relation and leaving the intermediate portion of said wall free to become distorted upon pouring, and exert a pressure on the mass poured in the mold; 35 and, means carried by said support and engaging the interme i te portion of the wall for normally holdin `the same against distortion, whereby uponreleasing said holding means, the wall will become suddenly distort- .40- ed and exert a pressure with increased force upon the mass poured in the mold.

8. In a mold for casting metals and metallic alloys, a wall made of a material subject to distortion when exposed to differences in 4a temperature; a cooling jacket about the outer side of said wall, and rigidly connected to the ends of the latter for maintaining said ends in fixed relation and leaving the intermediate portion of the wall free to become diso'torted upon pouring, and exert a pressure on the mass poured in the mold. h In1 witness whereof I have hereunto set my an v ABRAHAM M. ERICHSEN.

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