US2243425A - Casting of metals and/or metal alloys and more particularly to a method of maintaining a uniform rate of flow of the molten mass into the mold or chill - Google Patents

Description

May 27, 1941. s. JUNGHANS 2,243,425 CASTING OF METALS AND/OR METAL ALLOYS AND MORE PARTICULARLY TO A METHOD OF MAINTAINING A UNIFORM RATE OF FLOW OF THE MOLTEN MASS INTO THE MOLD OR CHILL Filed May 6, 1938 MWWW T J/W Mar: 4

Patented May 27, 1941 CASTING OF METALS AND/OR METAL AL- LOYS AND MORE PARTICULARLY TO A METHOD OF MAINTAINING A UNIFORM RATE OF FLOW OF .TBE MOLTEN MASS INTO THE MOLD OR CHILL Stuttgart, Wurttemberg,

Siegfried Junghans,

Germany, assignor t Irving Rossi, New York,

Application May 6, 1938, Serial No. 206,365 In Germany May 8, 1937 The invention relates to the casting of metals and/or metal alloys and more particularly to a method of maintaining a uniformrate of flow of the molten mass into the mold or chill. It is known that in order to obtain a satisfactory casting it is necessary for the metal always to flow into the casting box at uniform speed and/or quantity per unit of time and also at the same temperature. In order to fulfil these conditions it was hitherto necessary to convey the molten metal from'the containers therefor into the mold by means of pipe lines under pressure or by the aid of similar methods. In order to prevent the obtention of too great a quantity of metal these pipe lines had to possess relatively small cross sectional areas and in addition to be brought before the casting operation at least to the casting temperature of the metal concerned, otherwise the small bore would cause the metal to set at the beginning of the casting operation and thus to clog the pipe line." All these conditions 'hitherto made the metal supply complicated and itwas also impossible to cast metal and alloys having high casting tempera e's, such as copper, steel, tungsten because even to-day there is still 9 Claims. (01. 22-572) in the mold. This provides a possibility ofput-' ting into service a cold supply pipe, or at any rate a supply pipe which has not previously been heated to the casting temperature of ,the metal to be cast, by allowing the molten metal to be cast to flow through a pipe having a conveniently large diameter (about 10 mm.) and through a no satisfactory means of constructing pipe lines having a small cross-section of this character which could withstand such temperature, or of heating them to casting temperature before casting commences.

The invention overcomes these difficulties. It is based on the recognized fact that steel for example will flow through a pipe without difficulty even if the latter is not heated, provided that the internal diameter of the pipe is not less than about 10 to 15 mm. Now, the invention solves the problem of conveying the high melting point metals through pipes which are not narrower than 10 tol5 mm. into the mold and yet casting only such small quantities for which pipes of smaller diameter would have been suflicient. Considering the fact that in the casting processes hitherto used and which are now to be improved suitably large nozzle, in this way heating both pipe and nozzle, whereupon-as soon as pipe and nozzle have acquired the temperaturethe flow isso regulated as to correspond to the desired quantity per unit of time, which :is usually very small.

In this connection it is preferableto divertthe inflowing metal sideways and as far as possible uniformly, 'in order to obtain a uniform casting. To do this a device for intercepting and/or diverting the liquid jet entering the casting mold is arranged underneath the outlet nozzle, the said device in one embodiment in the form of a beaker,

, and in another example, in the formof a saucer by the invention, the nozzles have normally an internal diameter of between 3 and 10 mm. the invention now creates a device which on the one hand makes larger cross sectional areas possible at the commencement of the casting process while on the other hand-as soon as the process is proceeding-allows of regulating the diameter of the Jet so as to correspond to a quantity which a nozzle having a diameter of 3 to 10 mm. or a similar cross sectional area would allow to pass. Naturally the size of the cross section depends upon the quantity to be cast and upon the cross or plate.

Other important features of the invention will be apparent from the description, the claims and the attached drawing, which latter in Figures 1-6 illustrates the invention diagrammatically.

In Figure 1 a designates the supply pipe the upper end of which is located within a furnace J (Figure 2) the lower end extending into the casting mold b. The furnace f can either be a heating furnace for keeping the 'metal hot or 'a melting furnace. Instead of the said supply pipe a casting gutter can preferably be provided and fed from the melting furnaces or heating furnace. The supply pipe or rather the nozzle has in the present embodiment an internal diameter larger than 10 mm. A heating device a may be located at the lower end of the supply pipe. Heating of the supply pipe a may be effected in any desirable manner, e. g. electrically or by passing a heating medium therethrough. In Figure 2 electrical heating of the lower part of the inflow ipe a is shown. For this purpos electric current is supplied through the two conductors a and a so that a heating current flows through the su ply pipe and its resistance is used as a heating resistance. The casting mold b is preferably a chill which can be cooled. At the lower end of the supply pipe (I there is provided a shut-off or throttling member c, which can be optionally designed either as a cone c (Figure 1) or, a ball i (Figure 2) or as a valve or the like. The throttling member is connected by means of the system of rods d .to the controlling device c (Figure 1), e (Figure 2) or c (Figure 3) the said controlling device being actuated from without. By means of the entire regulating device (throttling member, rods and control member) the throttling member can be forced completely against the lower end of the supply pipe 41 thus completely closing it, or the throttling member is moved.

away from the outlet end of the pipe (.1 by means of the control device in such a way as toprovide a smaller or larger opening between the pipe a and the throttling member, thus allowing the metal in the pipe to flow into the chill in smaller or larger quantities. Due to the fact that the throttling member is kept within the liquid feeding head during the casting it is impossible for the throttling member to become "fro'zen even if as is mostly desired the quantity of molten metal flowing is very small. As may be seen from the drawing the throttling member can preferably be connected to a device in for intercepting or diverting the inflowing metal.

In the embodiment according to Figure 1 the casting proceeds as follows:

At flrst the connection between pipe outlet and thro'ttling member is completely opened.- The liquid metal is allowed to run into the supply pipe 11 which it heats while flowing through it. Further, the throttling member that is the valve cone 'has liquid metal poured over it and is thus also brought to the casting temperature. As soon as the chili is filled to such an extent that the valve cone is located within the liquid feeding head, the valve is so regulated by means of the device e as to allow only the requisite quantity of liquid metal to pass. The casting plant is then started up. As by this time supply pipe and valve possess the casting temperature the inflow can be adjusted as desired without the danger of freezing or other irregularities.

The temperature in the supply pipe can be maintained at a uniform level not only by adapting its cross sectional area to the amount of metal to be passed and to the temperature of the said metal but also by cooling or heating the said pipe from outside.

According to Figure 2 another embodiment of the regulating device is shown. The valve i is held in equilibrium by means of a spring n and a displaceable counterweight o,- by means of the system of rods it.

According to Figure 3 an automatic regulation is provided, by means of a float p which responds to the height of the surface of the metal in the chill and causes an equalizing effect to take place by means of the device e and the rods d and the valve cone, when the level of the metal varies or variation occurs in the amount of inflowlng metal.

A further possible form of the automatic regulator consists briefly of an arrangement in which the controlling device for the throttling member is so designed as to respond to the height of the liquid column or to the weight of the quantity of liquid lying above the valve, thereby regulating in known manner. Provision may with advantage be made for the furnace f, or the gutter with the supply pipe (I, to be arranged upon a balance, the variations in weight being utilized for regulating the quantity of inflowing metal with the aid of known means and in known manner.

Instead of the beaker m dish or plate like members can also preferablybe used in order to obtain satisfactory distribution of the metal. Embodiments following this line\of thought are shown in Figures 4 to 6.

In Figure 4 a designates the metal inlet pipe (nozzle) from which the metal flows on arriving from the heating furnace via a closed rising pipe or open gutter. b designates the chili and c the throttling member, the adjustment of which latter regulates the quantity of the flow..

The throttling member is located on a dish or plate like member m, the diameter and/or shape of which is adapted to the cross sectional area of the chill. The quantity of metal flowing in is regulated by means of the throttling member c operated by the adjustable regulating device 9, and at the same time evenly distributed over the whole of the dish m by means of the conical throttling member c. The molten mass flowing in is forced bythe plate pm to run out uniformly towards all sides of the chill and thus prevented from descending in the chill.

If a simple dish '11: is not sufficient to-produce smooth casting the pouring can be improved'by providing a second plate 1: above thep late'm as shown in Figure 5 the inlet pipe passing through the former. The distance between the plates m and n can be adjusted and according 'to this distance, or to the pressure under which the molten mass is forced through the inlet pipe 0, the metal jet flowing out will be more or less influenced.

In addition to ensuring uniform regulation of the flow of metal the device just described at a low casting temperature also effects a satisfactory distribution over the entire cross section, thus avoiding the deleterious piping or'funnelling effect which arises when the molten metal is poured down vertically into the metal in the mold.

When using distributors of the kind described it has been found that-at the commencement of the casting-so long as the distributor itself is not within the liquid metal, that is inside the liquid feeding head in the chill, there is a danger of the inflowing metal being squirted against the wall of the chill where it becomes "welded" to the well or spoilt. In order to avoid this a cap 8 is, at the commencement of the casting. placed over the distributor as shown in Figure 6, the said cap being removed as soon as the distributor lies within the liquid feeding head, as the latter will then damp and intercept the inflowing stream of metal. It has been found that castings made by means of devices according to the present invention possess a uniform, flne texture, which is more uniform and better than in casting made by means of the intercepting containers as in the embodiments according to Figures 1 to 3, which are in. the form of beakers, It has been found in particular that by means of the flat distribution of the 'inflowing metal the separation which occurs in the case of alloys disappears completely or almost so. It is therefore possible to obtain a casting free from liquation even when the cross sectional area is large.

By giving the distributing device an appropriate shape it is further possible to vary the texture or the separation or both conditions together in individual zones of the cross section, such va iation being under the operator's control.

The devices according to the invention can be used not only for small masses of metal but also for large quantities and suitable casting speed also in the case of small cross sections of chill.

It is of course not necessary that the distributor plate m shall be rigidly connected to the throttling member 0. Throttling member and distributor plate can be kept separate and moved or operated independently of one another.

It is also evident that the throttling member as well as the distributing plate can be controlled automatically separately or together by means of a device responding to the variations in height of weight of the liquid column of molten metal located above the throttling member in the casting pipe;

By means of the method according to the invention and the devices for, carrying it into effect the condition is fulfilled that constantly uniform quantities of metal shall fiow into the chill. A regulating is necessary owing to the fact that the level of metal in the container 1' from which the metal flow does not remain constant so that the rate of metal flow is altered. However, the method afiords the possibility of doing away with metal feeds through siphon-like devices, that is working with a rising pipe and pressure, inasmuch as according to the invention it is possible whether a melting furnace, a heating furnace or an interposed gutter is used, to attach the inlet pipe for the chill to the bottom of the furnace or container, without the necessity of keeping the metal in the furnace or container at the same level or of equalizing the variation in metal level in the furnace by means of pressure. This regulation is now taken over by the device in the chill, while the metal level in the furnace enters into the question only in so far as the higher this level is in the furnace, the more the valve in the chill will be closed, and vice versa. This also eliminates the not altogether simple replenishing of metal in the furnace under pressure, nor is it now necessary to keep the metal in the fur-- nace, container or gutter under the pressure of a pressure gas; this considerably simplifies the feeding of constantly uniform quantities of metal.

The invention thus aiIords not only the possibility of casting metals and alloys which owing to their high melting points could not be cast by the known methods, but also provides aconsiderable simplification of hitherto known devices, as it is of course also possible to cast according to the invention the lower melting point metals and alloys, such as aluminium and its alloys, magnesium-zinc and its alloys, etc. so that also thinner-inlet pipes can be used. According to the invention it is now also possible to let several outlet apertures lead downwardly out of the furnace or container, without the necessity of keeping the furnace under artificial pressure; which would require exact dimensioning of the bores of the pipes leading to the various chills. According to the invention the furnace or container can be kept at any desired pressure, and each inlet pipe to the chills is adjusted in the chill to the amount of metal required by means of a separate regulating device.

Experience has shown that when casting by means of a lifting pipe and accordingly with pressure in the furnace, and also with regulation of the throttling member, an extremely fine 'tained the nature of my regulation is obtained, which approaches very closely the desire for a completely automatic casting machine. Casting is then performed on such lines that in the furnace there is always maintained an even pressure (this can be accomplished by suitable automatic regulation means), fine differences in the height of the liquid metal in the chill being performed likewise automatically with the aid of regulating means such as; are described in the application.

The throttling member of the regulating device can at the same time be used also for adjusting the inflowing metal to a definite temperature either by cooling or heating, so as to be able to control the melting process in the chill or to adjust the same to absolute uniformity. According to the kind of metal to be cast the inlet pipe and valve may be made of refractory material or of metals having appropriate cooling devices.

Having now particularly described and ascerwhat manner the same is to be performed, I declare that what I claim is:

1. In a device for casting metals, a mold, a feed pipe for supplying molten metal to the said mold consisting of one of the following materials:

steatite, sillimanite, magnesite, sinter corundum spinell, and a throttling member for regulating the molten metal supplied by the said feed pipe, the said throttling member being constantly maintained within the liquid feeding head'of the metal in the mold.

2. In a device for casting metals, a mold, a feed pipe for supplying molten metal to the said mold, a throttling member for regulating the molten metal supplied by the said feed pipe, a substantially fiat plate arranged below the orifice of the said feed pipe, and a second plate arranged above the said first plate, the said orifice being disposed between the said two plates.

3. In a device for casting metals, a mold, a feed pipe for supplying molten metal to the said mold, a throttling member for regulating the molten metal supplied by the said feed pipe, a distributor arranged below the orifice of the said feed pipe, and a cap detachably secured above the said distributor, the said cap being closed at the sides and the top and open at the bottom.

4. In a device for casting metals, a mold, a feed pipe for supplying molten metal to the said mold, a throttling member for regulating the molten metal supplied by the said feed pipe, a distributor arranged below the orifice of the said feed pipe, said distributor being rigidly connected to said throttling member and a device acted upon by the molten metal in the said feed pipe and controlling the said throttling member, said throttling member being constantly maintained within lthe liquid feeding head of the metal in the mo d.

5. In a device for casting metals, a'mold, a feed pipe for supplying molten metal to said mold, a throttling member for regulating the molten metal supplied by said feed pipe, and a substantially fiat distributor. arranged. below the orifice of said feed pipe, said throttling member and said distributor being constantly maintained within the liquid feeding head of the metal in the mold, said distributor being rigidly connected to said throttling member. r

6. In a device for casting metals, a mold, a feed pipe for supplying molten metal to said mold, a throttling member for regulating the molten metal said invention, and in supplied by said feed pipe, and a substanlation to the orifice of thefeed pipe independently of said throttling member.

7. Process for casting molten metal in a metal mold, consisting in conveying the liquid metal by a conveying device directly into the liquid feeding head in the mold, throttling the metal stream flowing from said conveying device at a point within the feeding head, and heating the metal at the zone where throttling takes place.

8. Process for casting molten metal out of a container into a metal mold, in which the liquid metal is conveyed by a conveying device directly into the liquid feeding head in the mold, and the metal stream is throttled within the feeding head,

consisting in pouring liquid metal into said mold at the beginning of the casting operation without throttling the flow, and thereafter during the continuance of the casting operation throttling the flow within the liquid head after the liquid head of metal is of suiilcient depth to cover the throttling device.

9. The method of feeding molten metal from a furnace to a casting mold through a feeding pipe which comprises maintaining the molten metal in said furnace under constant and uniform pressure to cause a substantially uniform rate of flow through said feed pipe, and additionally controlling the rate of flow through said feed pipe by varying the size of the discharge 'opening thereof below the surface of the metal already in the mold.

" SIEGFRIED JUNGHANS.

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