US2287848A - Method of casting - Google Patents

Description

3 Sheets-Sheet l C. WESSEL METHOD OF CASTING SCI Filed Jan. 16, 1939 Izz eza Z31" Cari fleasei June 30, 1942.

HF HHH h l l l l U" H l June 30, 1942-. c. WESSEL 2,287,848

METHOD OF CASTING Filed 1939 s Sheets-Sheet 2 June 30, 1942. c. w EssEL METHOD OF CASTING Filed Jan. 16, 1939 3 Sheets-Sheet 3 Q NQ Q E NWN @NNN fiaVemZ'ar: Carl flesael Patented June 30, 1942 METHOD or CASTING' Carl Wessel, Chicago, 111., assignor, by mesne assignments, to Carl Wessel and Lew W. Cleminson, both of Chicago, 111., trustees Application January 16, 1939, Serial No. 251,092

9 Claims. (Cl. 22-57) The present invention relates to methods of casting, and is particularly concerned with methods for producing better castings and better metal stock of various shapes more efiiciently and more economically than can be done by the methods and apparatus of the prior art.

One of the objects of the present invention is the provision of an improved method of casting metal, utilizing refractory or metal molds, and filling the mold by gravity of the liquid metal in such manner that the complete filling of the mold is effected and the shinkage is avoided by the continuous application of liquid metal under pressure, due to gravity head, while the casting is cooling from its most remote end toward the filling gate.

Another object of the invention is the provision of an improved method of casting by means of which extremely thin sections may be made and by means of which the freezing of a part of the metal during the pouring process, commonly referred to as blow-holes, may be eliminated.

Another object of the invention is the provision of an improved method of casting which produces an absolutely solid casting and produces a high degree of uniformity of crystal structure of the casting, and which is also economical in its operation.

Another object of the invention is the provision of an improved method of casting which avoids the contamination of the metal by filling the mold without the liquid metal coming in contact with any air except that small amount which is present in the mold.

Another object of the invention is the provision time, so that the congelation of the metal may be accomplished while pressure is applied.

Another object of the invention is the provision of improved methods which are not only adaptable for individual casting and small plants but for mass production.

Another object of the invention is the provision of an improved method of producing sheets, strips, and stock shapes of metal, by meansof which much costly rolling and annealing equipment may be eliminated, and by means of which stock shapes thin enough and possessing the necessary homogeneity for finishing and rolling purposes may be made, thereby reducing the cost of production and capital required for equipment.

Another object of the invention is the provision of improved castings and methods for producing castings, by means of which shrinkage, flaws, and the formation of pipes and shrinking strains are eliminated, and castings of uniform crystal structure may be produced at a mini-' mum cost.

Another object of the invention is the provision of an improved casting method which permits the melting and casting of the metal under reduced air, or controlled air conditions as required by the metal used.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the three sheets of drawings which accompany this specification,

Fig. 1 is a diagrammatic top plan view of a plurality of melting furnaces arranged for discharge into a centrally located ladle;

Fig. 2 is a similar view of a modified furnace and ladle arrangement;

Fig. 3 is a horizontal sectional View, taken on the plane of the line 33 of Fig. 4, showing the structure of the ladle of Figs. 1 and 2;

Fig. 4 is a vertical sectional view, taken on the plane of the line 44 of Fig. 3', looking in the direction of the arrows, showing the structure of the ladle and the closely associated part of the mold;

Fig. 5 is a fragmentary sectional view of a modified form of connection between the ladle and the mold, which may be utilized in Fig. 4;

Fig. 6 is a fragmentary elevational front view of the front part of the ladle and conveying mechanism for supporting the molds in pouring position.

Referring to Figs. 1 and 2, these are diagrammatic arrangements of a plurality of furnaces, shown in connection with a ladle of the type illustrated in Figs. 3 and 4.

According to my method of operation in a foundry of suitable size, the ladle 20 is provided with an insulating lining 2| and is adapted to receive within its chamber H a suitable supply of molten metal for continuous casting operation.

The ladle 20 is a fixed ladle, and by means of its insulating lining 2| it maintains the metal at a suitable high degree of temperature for casting operations the metal being discharged from the discharge aperture 23 at the lower part of the ladle 20.

The furnaces 23-26 may be arranged in a circle about the upper part of the ladle 20, that is, on an upper floor, in such manner that each furnace may have its discharge conduit 21 of equal length to those of the other furnaces, and the furnaces are to be periodically charged with a batch of metal to be melted and successively discharged into the ladle 20.

Different numbers of melting furnaces may, of course, be employed, the furnaces preferably being of the rotating tilting type. For example, if four furnaces are employed, a, batch might be discharged into the ladle every fifteen minutes, the capacity of each furnace being about 250 pounds per hour; while, if three furnaces were employed, a batch would be discharged every twenty minutes. Under these conditions the capacity of the ladle might be approximately 1200 pounds or two cubic feet, and the inner measurements of the ladle might be, for example, ten inches inner diameter by thirty inches high.

The temperature of the metal discharged from the furnaces might be approximately 2200 degrees F., and the temperature of the metal in the ladle might be slightly lower, but need not vary more than about 200 degrees F., as the heat of the metal in the ladle would be continuously replenished by the periodic discharge into the ladle of hotter metal from the furnaces.

Each furnace is preferably provided with a rotating discharge spout 21, and the ladle or reservoir 20 is preferably provided with a suitable cover, which is removable, so that the metal is enclosed from the time it is melted in the fur nace and during its discharge into the ladle and during its discharge from the ladle into the mold, as be will further described.

A cleaning of the metal is effected in the furnace before the pouring operation by scraping out the dross and slag, with the furnace almost in level position, the scraping being effected through a discharge opening,

The melting may then be accomplished under reduced air and controlled conditions.

In the example of a furnace and ladle proportions cited, the head of pressure might vary from full head in the ladle to half head during most of the days casting. At the end of the days run, the reduced head, from one-half to zero in the ladle, would be utilized for the casting of relatively small molds, which would not require as much gravity head as the larger castings. The total capacity per day for an eight hour day of casting would be approximately 7,000 pounds.

As the practice of the method may be made more clear by reference to one example of the apparatus, I shall now describe in full one form of apparatus which may be used for practicing the invention. i

Referring to Fig. 1, each of the melting furnaces 2326 is, of course, provided with a suitable heating device, such as a gas or oil burner,

and may be provided with a motor for rotating I conduits 3|, 35 and 35, 31 are jointly to conduits 38, 39 respectively. In this case the lengths of the eonduits for all of the furnaces are not equal,

ijito the discharge conduits 34-31, and the two but by means of the use of. a suitable refractory lining for the metal jacketed conduits 34-39 the excessive loss of heat can be practically elimi nated and practically the same discharge temperature secured for the batch from each furnace,

In the event the end furnaces 30 and 33 give evidence of slightly greater cooling of the batch as it discharges down the elongated conduits 3|, 38 and 31, 39, the end furnaces can be operated at slightly higher temperatures, to effect equalization of the temperature of the batches discharged into ladle 20, which is similar in construction to the ladle or reservoir 20, previously described.

Referring to Figs. 3-6, these are detailed illustrations of the structure of the reservoir or ladle for melted metal and the arrangements for filling molds from this reservoir.

In Figs. 3 and 4 the ladle, which is indicated in its entirety by the numeral 20, may have its interior insulation 2| formed in a plurality of layers, the layers comprising, respectively, the inner refractory 40, the firebrick H and the rock wool or asbestos flber insulation 42.

The ladle 20 is preferably supported upon a suitable concrete foundation 43 and may have its external metal jacket 44 built up of a multiplicity of metal sections 45-5l. These metal sections are in the form of endless metal bands of cylindrical shape, each successive section being supported upon the one below it so that the ladle can be built to any desired height.

The metal jacket sections 455l are given additional support and held in alignment with each other by a plurality of vertically extending eye beams 5255 (Fig. 3), which are preferably equally spaced about the periphery of the metal jacket 44, extend axially thereof, and are located in contact with the external cylindrical surface of the jacket sections l5.-5l.

At each joint between the jacket sections there is a metal band 58-5l, and each metal band may be of similar construction to those shown in Fig. 3, The metal bands 58-5I are bent to substantially partially cylindrical form, and are long enough to encompass that portion of the periphery which is located between the flanges of a pair of eye beams 52-55. Any number of eye beams may be employed, but in a furnace of the size mentioned above I consider four eye beams sufficient, and the metal bands SI, for example, contact the external surfaces of the sections 50 and 5| of the jacket 44 throughout the major portion of their length, and are bent outward at 62 or provided with an offset 62 at each end so as to engage outside the inner flange 63 of the eye beams.

The band BI is also provided with an attachment flange 54 extending radially at each end and adapted to engage the web 65 of the eye beam 54 or 55, and the attachment flanges 54 are provided with apertures for receiving the screw bolts 58, which pass through the attachment flanges B4 and through the web 65, and secure two of the attachment flanges of the bands 56-6l to each web.

The bands 56-6| are slightly shorter in length than the spaces between the webs of the respective eye beams 54, 55 so that there is a tolerance to be taken up by means of the bolts 56, which draw the bands tightly about the metal sections 45--5l the jacket 44 and assure the securement of these bands against vertical movement due to the frictional engagement between the bands and the metal sections.

Ihe ladle also comprises an iinner metal shell of similar construction to the metal shell N, or the inner metal shell may comprise the simple annular bands of metal, such as steel, mounted,

as Amosite, glass wool, or quartz wool, for the purpose of conserving the heat in the ladle.

Inside the shell 10, the ladle 20 is provided with the layer 4| of firebrick, molded to fit together to form a wall which is annular in plan, and the firebrick preferably have their joints overlapping the joints between the sections of the inner shell 10. For example, if the firebrick are also one foot high, then this also facilitates the building of various sizes of ladles or reservoirs which differ in height by a foot.

The innermost layer of insulation comprises the refractory lining 40, which consists of a refractory composition that is smooth but not glazed, and which may be treated with flux or charcoal to prevent the metal from sticking to it.

The composition may include metal dioxides, clay, and feldspar, and such refractory linings may be made absolutely smooth so that the metal in the reservoir can be kept clean.

A de-oxidizer compound can be kept on top of the charge in the reservoir or ladle 20 for the purpose of preventing any air contamination.

The refractory lining 40 is also in the form of peripheral sections, which, for example, may be a foot high, and all of which fit together smoothly to form the cylindrical reservoir chamber 1| for receiving the molten metal. This chamber is substantially cylindrical in shape at its uppermost portion, such as, for example, the sections 12, 13, 14, or but at its bottom the chamber 1I tapers in diameter and is curved laterally toward the discharge port 23. Thus the section 18 of the ladle chamber 1I tapers from the initial diameter to approximately half the diameter, and extends toward the left in Fig. 3, in a streamlined curve. The refractory blocks 11 adjacent this section are, of course, suitably formed for this purpose.

The refractory blocks 18 of the lowermost sec tion have formed in them, when assembled, a continuation 19 of the tapered throat 18, which tapers still farther along smoothly curved lines toward the reduced conduit 80 in the refractory block 8| at the side wall of the ladle.

The metal jacket section 48 is provided with an enlarged aperture 82 for receiving the refractory block 83, which may be cylindrical in form, and

which is provided with the discharge aperture 23, forming a continuation of the conduit 80.

The refractory block may be housed in a cast metal fitting 84, (Fig. 4), which is provided with an inner curved surface 85, and peripherally extending fianges 86, 81 fit against a metal 4 band surrounding the wall of the section 86,- to which the flanges B6, 81 are bolted by means of the screw bolts 88, which have their threaded ends projecting outward from the shell 46.

The fitting 84 may be built up in the form of a plurality of metal sections 90, 9|, 92, bolted or otherwise secured together, but the external portion 92 thereof is provided with laterally proeach other and in straight lines so that the flanges 91, 98 carried by the mold may be slidably mounted in the grooves 95, 98. Each-of the molds IOU-I05 may comprise a metal lining and an external metal jacket I08 formed of two similar halves I01, I08 fitting together.

In other cases the jacket halves I01, I08 are lined with an inner layer I09, IIO of, smooth high-temperature -resistant and heat-insulating refractory, previously mentioned, which is used to line the innermost chamber 1| of the ladle, and the refractory sections I09, N0 of the mold have the casting cavity III formed in them, and are separable at the same join't II2 as the metal halves I01, I08 of the jacket I08. For the purpose of illustration, the mold IIII is illustrated with a jacket comprising two separable sections which are clamped or bolted together in any suitable way, preferably by means of pivoted bolts and wing nuts so that the molds may be removed quickly at the proper time. However, the molds may be made of any number of sections suitable to the nature of the shape of the casting so as to facilitate the removal of the mold from the casting as soon as it has congealed, without breaking any part of the casting.

The proper number of sections for a jacket or refractory lining of a mold will be evident to any one skilled in the art of molding.

The present molds are adapted to be used over and over again, and are practically indestructible. They are also preheated before use, and are maintained in a heated condition by reuse, the number of molds being adapted to the continuous operation of the machine by the use of a mold practically as soon as it has been removed from one congealed casting which is still at a highly heated condition.

The refractory sections of the mold are formed with the semi-cylindrical grooves H3, I, which together form an aperture or conduit that m creases in size gradually as it extends downwardly and laterally, and the aperture II8 of this conduit II5 fits the discharge aperture 23 of the ladle.

The metal jacket I08 of each mold has a diagonallydownward and laterally extending formation which is adapted to be secured to the guide fitting I I1, having the flanges 91, 98 previously mentioned. This guide fitting has a pair of outwardly extending fianges I I8 and a pair of downwardly and upwardly extending flanges H9, and is provided with set screws I20 for securement to the mold.

It will be noted that in Fig. 4 the mold IIII, which is for a relatively fiat casting, extends diagonally upwardly. This is for the purpose of permitting the filling of the mold by the flowing upward of the melted metal in the mold, without any splashing or formation of drops.

It is contemplated that no special gates will be required for the discharge of the air in the mold, as the air may leak out between the two halves of the refractory lining and metal jacket of the mold, which are fitted closely enough to mold the casting with practically no fin, but still permit the escape of air.

It will be noted that the reservoir or ladle 20 isformed with a downwardly and laterally extending discharge conduit, which tapers gradually to its smallest section at the mouth I2I of the casting cavity. The molds may thus be slidably.

straight line, so as to support a multiplicity of molds, as shown in Fig. 6. In some embodiments of the invention the ladle may be provided with a plurality of discharge openings for an equal number of molds.

In some plants the molds may be shoved past the discharge aperture 23 of the ladle by hand. As soon as the aperture II6 of the mold has passed the discharge aperture 23, the further discharge of melted metal is arrested by the fact that the flat surfaces on the face I22 of the refractory of the mold cover up the discharge aperture 23.

If desired, a suitable steel die may be provided at this face I22 for shearing off any metal which may have congealed.

In the practice of my method, the metal, which may be congealed slightly, will still be capable of being sheared off at this time. I

When the molds are shoved into place by of the stop member out of its operative position will permit the progress of the mold from the casting position to a position further on in the guides of the guide fixture 84.

In other embodiments of the invention a suitable driving mechanism may be provided, such as, for example, the frame members I (Fig. 6) which support a driving rack I3I that is slidably mounted by means of the pins I32 in slots I33 below the molds.

This rock may be spring-urged toward the right by means of a tension spring I34 engaging a pin on the rack, and having its opposite end secured to a frame member. The rack is provided with a plurality of pawls I35I4II. Each pawl I35-I46 is pivotally mounted upon a pin HI and engages a stop member I42, toward which it is pulled by means of a spring I43.

The rack bar I3I also has a driving pin I suitably located to be engaged by the shoulder I49 carried by a rotating drive wheel I50 mounted on shaft I5I.

The operation of this step-by-step mechanism is as follows: Shaft I5I may rotate at a constant speed, which is determined by the length of time required for the making of one casting. This time will be sufficient, as hereinafter more fully described, to permit not only the filling of the mold with melted metal, but the continued application of melted metal under gravity head to the mold while the casting congeals from its outermost point. inward toward the supply of metal in the reservoir.

During this congelation the shrinkage of the casting is taken up by the supply of additional metal from the molten end of the casting, and the last part of the casting to freeze should be that adjacent the mouth I2I of the mold. Thus the actuating shoulder I49 performs a rotation in a predetermined time, which is determined by the characteristics of the casting or mold and by the time required to carry out my process.

When the shoulder I49 engages the pin I45, it causes the rack I3I to move to the left by an amount equal to the length of a slot I33, which is suiiicient to move one mold IIII from the position which it occupies in Fig. 5, in registry with the discharge aperture 23, and to bring the next mold I02 into that same position. Thereafter the shoulder I49 slips off and passes the pin I45, due to the rotation of the wheel I 50, and the spring I34 returns the rack I3I, during which movement all of the pawls I35-I4II are adapted to slide past the molds which are immediately to the right of each pawl.

The pawls are then in position to engage and actuate these molds when the rack has reached the position of Fig. 6 again. Thus the mechanism is adapted to effect the movement of the molds in a step-by-step manner and to permit the molds to remain in casting position for a predetermined length of time.

Referring again to Fig. 4, the ladle is preferably provided with a fixed cover member I60, which may comprise a metal jacket I6I having an external cylindrical portion I62 and a flat end portion I63.

The Jacket I 6| may be bolted in place by means of the bolts I64 and flanges I65, I66. The jacket may have a centrally located aperture I61 with a downwardly extending frusto-conical flange I68. The jacket is lined with a flat block of refractory I 69 in the form of a disc having a centrally located frusto-conical bore I10 fitting against the flange I68.

This aperture I10 serves as a filling opening for the reservoir or ladle 1|, and it in turn may be closed by a movable cover member III, which has a metal 'jacket I12 anda refractory lining I13 retained by means of a frusto-conical flange I14. The movable cover I1I fits in the bore I61 and produces an effective closure, due to the engagement of the metal flanges I68 and I14.

The movable cover "I may be provided with a centrally located air aperture I15, communicating with a counterbore I16 for receiving a conical valve member I11. The valve member I11 has a stem I18 guided in an aperture in the jacket I12 and urged to closed position by a spring I19. The stem I 18 has a transverse pin I engaging in a slot in the end of a lever I8I.

The lever I8I is pivoted on the bracket I82 and provided at its opposite end with a pull rod I83 slidably mounted in a guide fixture I84 and provided with a ball counter-balance I85. By means of a pull on the rod I83 the operator may regulate the admission of air to the chamber 1| of ladle 20, and thus control, at least in some measure, the discharge of metal from its lower end.

Thus the pull rod I83 would be pulled whenever the mold was in front of the discharge aperture of the ladle, and the actuation of the rod may be gradual, in order to permit the filling of the mold without any splashing, or to reduce the impact which results when the molten metal flowing into the mold reaches the end of the mold.

Referring to Fig. 5, this is a modification in which the conduit I I5 is provided with a butterfly valve 216 for controlling the flow of the metal into the mold.

This valve may be so constructed that its actuating shaft may be withdrawn, and that portion of the conduit II5 surrounding it may be separated when the mold is separated, so that the metal in the conduit II5 may be removed from the conduit with the valve 210, and a new valve substituted when the mold is again used.

My method of casting is briefly described as follows: When a ladle of the type described is used, the ladle is constantly supplied with new batches-of molten metal, from which all dross or scum have been removed in the furnace, and this metal is supplied to the ladle without exposure to the air, so far as possible.

A de-oxidizer compound may be kept on top of the charge, to prevent air contamination.

The molten metal is kept in the ladle, which is lined with smooth refractory, suitably treated with flux or charcoal, to prevent the metal from sticking to it, and suitably insulated, so that the metal may be maintained at a high temperature, with a minimum fluctuation of temperature between batches.

When ordinary castings are to be made, the mold is made of a similar smooth refractory capable of retaining the heat, and providing heat insulation for the casting, and the mold is pre-heated either by a preheating operation or by being used over and over again, immediately after a previous casting operation.

The mold and the ladle have their entry and discharge openings and conduit for the metal smoothly tapered along stream lines so that there will be no splashing and the least amount of agitation of the metal.

The mold may be lined with metal inside the refractory to reduce breakage of molds and improve castings and whencasting with certain metals, I use metal molds where it is economical.

The mold is tilted upward from its filling opening so that metal running into the mold cannot drop down to the end of the mold and splash. After the mold opening is placed in registry with the discharge opening of the ladle, the molten metal is permitted to well up into the mold, its level constantl rising, until it completely fills the mold.

During this time the metal is still molten and maintained heated because of the insulating character of the refractory mold or the preheating of the mold.

The mold may, in the case of relatively large castings, be provided with apertures for the issuance of the air, but in most cases the air will leak out between the halves of the mold, and the molds in such case will not need risers.

The method may be practised with all types of metals. The thickness of the refractory in the mold and in the ladle are proportionate to the bulk of the metal in the casting or the bulk of the metal in the ladle, respectively.

After the mold has been filled, it is then maintaiaed in the same position, withthe metal of the ladle pressing into the mold, due to the head of the metal in the ladle, until the metal has solidified in the mold.

During this operation the pouring end of the mold is the hottest, and the end farthest from the ladle is the coolest. There is a heat gradient extending from the ladle outward to the extreme end of the mold. As the metal solidifies, it begins to solidify at the extreme end of the mold, away from the ladle, and gradually solidifies downward toward the filling opening of the mold. During this operation any shrinkage is taken up by the supply of additional melted metal, due to the head of the metal in the ladle.

There will be no flaws or pipes, nor will the casting be subjected to strains due to unequal contraction. The entire mold will be filled, and the casting will correspond more closely to the shape of the mold than with the methods of the prior art.

After the casting has solidified in the mold down to the filling opening of the mold; the further flow of metal into the mold is cut off by sliding the mold sidewise so that the stream of metal is sheared off. If it has solidified down to the point of shearing, it can still be sheared 01?, due to its relative softness at such a high temperature, and the discharge aperture of the ladle is closed by a flat surface on the end of the mold.

The next mold continues to close this discharge opening b a similar flat surface until its filling opening comes in registry with the discharge opening of the ladle, after which the filling of mold is again resumed.

The mold, which has been filled and removed from its ladle, has its parts separated, and the casting is removed at a proper time, which is determined by the character of the casting. This enables the use-of the mold over again while it is still in a heated condition, and the casting may contract as it cools, without producing any strains on the mold or breaking the mold. The casting may contract more freely than if it were left in' the mold.

Castings may thus made to closer tolerances, and the present method makes sure the elimination of flaws because of the constant application of liquid metal under pressure to the molten side of the casting, as the casting solidifies. There is no chance of getting drops of metal in the mold, as the metal wells up into the mold, due to the tilt of the moldwith respect to its filling opening.

Such drops frequently happen in the. casting methods of the prior art on account of splashing or agitation, and such drops solidify on the way down into the mold, in the devices of the prior art. This cannot happen according to my method.

One of the most important features of the method is the freezing of the metal last at the mouth of the mold and at the beginning of the freezingat the point farthest away from the mouth of the mold. In some castings gates may be provided at the most remote point of the mold. A rim around the casting may usually be avoided because such heavy pressures are not employed in my method as in die casting.

The castings, after removal from the mold, are preferably subjected to the uniform foundry temperature of approximately 65 degrees F., and kept out of draft. They could also be quenched in water, if desired, but are preferably cooled uniformly by being subjected to a moderate and uniform cooling temperature so that they will contract in proportion, everywhere in the casting.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but, desire to avail myself of all changes within the scope of the appended claims.

Patent of the United States, is:

l. The method of casting which comprises melting the casting metal in a plurality of melting furnaces arranged to provide batches of molten metal for discharge into a ladle at regular intervals to maintain the head of metal in said ladle at predetermined height and to maintain the high temperature of metal in said ladle, maintaining the temperature of the metal in said ladle by insulation and by periodic supply of hotter metal, discharging the molten metal from said ladle at its lower end laterally and upwardly into a mold having a cavity and a downwardly directed filling opening, the molten metal Welling up into said mold to fill the mold without splashing, and with a minimum contact of molten metal to the air in the mold, maintaining the temperature of the casting metal in the mold cavity by insulation of said mold, and keeping the mold in connection with the supply of molten metal while the metal solidifies in the mold, beginning at a point remote from the filling opening, downward to the filling opening, whereby the shrinkage is taken up by the supply of additional molten metal from said ladle until the temiined temperature from said container directly into a mold, through a relatively large stream-lined discharge opening, the transfer of metal from ladle to mold being from a point below the free surface of the molten metal in the container at the time of transfer, and said mold having its cavity extending upward from said discharge opening at the time of transfer, the transfer of the metal from container to mold taking place in the form of a gradual welling up of a solid stream of metal in the mold without splashing or spurting or separation of molten metal from the main body of said stream until the mold is filled by gravity head, and thereafter maintaining a gravity head pressure on said mold in excess of the head of metal in said mold for a predetermined period of time to supply metal to the interior of the casting during congelation and shrinkage, the casting solidifying from a point farthermost from said discharge opening down toward said discharge opening.

3. The method of casting which comprises providing a supply of molten metalin an insulated container, and maintaining the temperature of said metal at a predetermined temperature, transferring molten metal at said predetermined temperature from said container directly into a mold, through a relatively large streamlined discharge opening, the transfer of metal from ladle to mold being from a point below the free surface of the molten metal in the container at the time of transfer, and said mold having its cavity extending upward. from said discharge opening at the time of transfer, the transfer of the metal from container to mold taking place in the form of a gradual wellingup'of a solid stream of metal in the mold without splashing or spurting or separation of molten metal from the main body of said stream until the mold is filled by gravity head, and thereafter maintaining a gravity head pressure on said mold in excess of the head of metal in said mold for a predetermined period of time to supply metal to the interior of the casting during congelation and shrinkage, the casting solidifying from a point farthermost from said discharge opening down toward said discharge opening, and removing said casting from its mold promptly after solidification of the metal of the casting down to said discharge opening.

4. The method of making metal castings of homogeneous uniform-grained structure which comprises melting a supply of clean metal in a plurality of furnaces arranged adjacent a heat ofthe metal directly into a preheated metal mold constructed of a metal of higher melting point than the casting metal, said mold extending upward from its filling opening, whereby the metal wells upward into the mold without splashing due to the gravity head of metal in the, ladle until the mold is filled, maintaining the gravity head on the metal in the mold thereafter in excess of the head of metal in said mold for a predetermined period of time to supply metal to the interior of the casting during congelation and shrinkage, the casting cooling naturally by radiation and conduction and solidifying from a point farthermost from said discharge opening and inwardly from the sides of said mold down toward the discharge opening and stopping the application of pressure head to said casting when the casting has congealed just past the filling opening of the mold.

5. The method of making metal castings of homogeneous uniform-grained structure which comprises melting a supply of clean metal in a plurality of furnaces arranged adjacent a heat insulated ladle, to a predetermined elevated temperature, maintaining a supply of said melted metal in the heat insulated ladle at a predetermined lower temperature by periodically discharging metal successively from said furnaces into said ladle, discharging the molten metal from said ladle at a point below the free surface of the metal directly into a preheated metal mold constructed of a metal of higher melting point than the casting metal, said mold extending upward from its filled opening, whereby the metal wells upward into the mold without splashing due to the gravity head of metal in the ladle until the mold is filled, maintaining the gravity head on the metal in the mold thereafter in excess of the head of metal in said mold for a predetermined period of time to supply metal to the interior of the castingduring congelation and shrinkag the casting cooling naturally by radiation and conduction and solidifying from a point farthermost from said discharge opening and inwardly from the sides of said mold down toward thedischarge opening and stopping the application of pressure head to said casting when the casting has congealed just past the filling opening of the mold, the said ladle and mold being closed to minimize the oxidation of metal at the free surface, and the mold being heat insulated to eliminate the possibility of cooling by extraneous influences.

6. The method of making metal castings of' homogeneous uniform-grained structure which comprises melting a supply of clean metal in a plurality of furnaces arranged adjacent a heat insulated ladle, to a predetermined elevated temperature, maintaining a supply of said melted metal in the heat insulated ladle at a predeter- 'mined lower temperature by periodically diswells upward into the mold without splashing due to the gravity head of metal in the ladle until the mold is filled; maintaining the gravity head on the metal in the mold thereafter in excess of the head of metal in said mold for a predetermined period of time to supply metal to the interior of the casting during congelation and shrinkage, the-casting cooling naturally by radiation and conduction and solidifying from a point farthermost from said discharge opening and inwardly from the sides of said mold down toward the discharge opening and stopping the application of pressure head to said casting when the casting has congealed just past the filling opening of the mold, and separating the casting and mold promptlyafter solidification to permit the shrinkage of the casting without constraint.

'7. The method of making metal castings of homogeneous uniform-grained structure which comprises melting a supply of clean metal in a plurality of furnaces arranged adjacent a. heat insulated ladle, to a predetermined elevated temperature, maintaining a supply of said melted metal in the heat insulated ladle at a predetermined lower temperature by periodically discharging metal successively from said furnaces into said ladle, discharging the molten metal from said ladle at a point below the free surface of the metal directly into a preheated metal mold constructed of a metal of higher melting point than the casting metal, said mold extending upward from its filling opening, whereby the metal wells upward into the mold without splashing due to the gravity head of metal in the ladle until the mold is filled, maintaining the gravity head on the metal in the mold thereafter in excess of the head of metal in said mold for a predetermined period of time to supply metal to the interior of the casting during congelation and shrinkage, the casting cooling naturally by radiation and conduction and solidifying from a point farthermost from said discharge opening and inwardly from the sides of said mold down metal directly into a preheated mold constructed of material of higher melting point than the casting metal,said mold having its major axis extending upward from its filling opening at an angle which is ,oblique with respect to the free surface of the molten metal, whereby the metal wells upward into the mold in a solid stream of metal without splashing orspurting or separation of molten metal from the inain body of said stream, with its free surface progressing upward from the filling opening to the top of the mold, until the mold is filled by gravity head, and thereafter maintaining a gravity head pressure on the metal in said mold by means of the molten metal in said container, in excess of the head of the metal in said mold for a predetermined period of .time to supply metal to the interior of the casting during congelation and shrinkage, the casting cooling and solidifying from a point farthermost from said discharge opening, and

inwardly from the sides of said mold down tof ward the discharge opening, and causing the toward the discharge opening and stopping the 8. The method of making metal castings having a homogeneous uniform-grained structure, which comprises providing a supply of clean molten metal in a heat insulated container, discharging the molten metal from said container at a point below the free surface of the molten cessation of the application of pressure to said, casting when the casting has congealed to a pre-- determined point.

9. The method of making metal castings having a" homogeneous uniformrained structure, which comprises providing a supply of clean molten metal in a heat insulated container, discharging the molten metal from said container at a point below the free surface of the molten metal directly into a preheated mold constructed of material of higher melting point than the casting metal, said mold having its major axis extending upward from its filling opening at an angle which is oblique with respect to the free surface of the molten metal, whereby the metal wells upward into the mold in a solid stream of metal without splashing or spurting or separation of molten metal from the main body of said stream, with its free surface progressing upward from the filling opening to the top of the mold,

-until the mold is filled by gravityhead, .and thereafter maintaining a gravity headpressure on the metal in said mold by means of the molten metal in said container, in excess of the head of the metal in said mold for a predetermined period of time to supply metal to the interior of the casting during congelation and shrinkage, the casting cooling and solidifying from a point farthermost from said discharge opening, and inwardly from the sides of said mold down toward the discharge opening, and causing the cessation of the application of pressure to said casting when the casting has congealed to a predetermined point, and removing said casting from its mold promptly after solidification of the metal of the casting to permit the casting to contract without the restraint of the mold.

CARL WESSEL.

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