US2117114A - Apparatus for casting metal - Google Patents

Description

May 10, 1938; w HAZEY 2,117,114

APPARATUS FOR CASTING METAL Filed Dec. 7, 1954 2 Sheets-Sheet 1 2 Sheets-Sheet 2 May 10, 1938. G. w. HAZEY APPARATUS FOR CASTING METAL Filed Dec. 7, 1954 Patented May 10, 1938 UNITED STATES PATENT OFFICE APPARATUS FOR CASTING METAL Application December 7, 1934, Serial No. 756,496

9 Claims.

This invention relates to the art of casting metal, and particularly to that phase of the art concerned with eliminating and avoiding imperfections in the articles cast. More particularly,

my invention concerns the elimination of blow' holes, fissures, pipe and other objectionable flaws frequently found in the cast metal when it has solidified. Although my invention may be used in casting ingots of various metals, a convenient example of its efiicacy is illustrated by the example of steel poured into ingot molds in the casting of ingots which later are to be shaped in rolling mills.

It has been customary, when casting steel ingots, to transfer the molten metal from the furnace or converter to a large teeming ladle. This ladle was then transported to the pouring fioor and the ingot molds successfully filled. When the metal had cooled and the mold had been removed 20 from thereabout, an examination of the ingots thus formed usually revealed several defects.

A pipe would have formed adjacent the vertical axis of the ingot, extending from the top downwardly, sometimes for about half the depth 25 of the entire ingot. Oxidation of the exposed pipe surface prevented the metal from knitting properly into an integral piece when passed through the rolls of a mill. Hence, that portion of the ingot affected by the pipe had to be cut 30 off and discarded,a very wasteful loss of time and material, even though the discarded portion could be remelted.

The inclusion of gas and air bubbles in the ingot was also harmful because the gas so confined would react with the hot metal to form a thin film, for instance an oxide, about the surface of the metal exposed to the. bubbles. This film of combined metal would also prevent the opposite portions of the ingot from knitting under 40 the rolling action, and thus leave defects on the finished product.

It has, in general, been an object of my invention to eliminate the defects above mentioned from metal ingots. More specifically stated, it

clusion of objectionable gases and other foreign substances within the casting; it is also an object of my invention to eliminate shrinkage defects, known in ingot casting as pipe.

It will be apparent from these objects that I contemplate employing the apparatus comprising my invention in conjunction with metals other than steel, although it is with that metal that my invention is particularly concerned. My invention will. become more apparent from the acis an object of my invention to prevent the incompanying description and the drawings included therewith, the various salient features of the invention being set out in the claims.

In general, my invention comprises an appara -tus to be used for removing as much of the gas confined within the empty ingot molds as possible. It is by the achievement of a partial vacuum within the molds, while the metal is being poured, and both before and after pouring, if desired, that I accomplish the objects above enumerated. The higher the degree of vacuum obtainable, the better will be the results, and the more perfect the final castings.

When my invention is incorporated in the process of casting steel ingots, I provide an ap paratus carried by the teeming ladle, by means of which the desired vacuum within the mold is obtaimxi. This apparatus comprises a boxshaped enclosure, carried on the bottom of the ladle and surrounding the pouring nozzle. At its lower end, the box, which I call a vacuum box is shaped to fittightly around the edges of the upper end of an ingot mold. When the box is seated properly on top of the ingot mold, there will thus be provided a relatively air-tight chamber, comprising the interior of the vacuum box and the interior of the ingot mold. It is the chamber so formed from which I evacuate gas contained therein, and thus accomplish the objects of my invention.

Referring now to the drawings, Fig. 1 is an elevation, showing a teeming ladle with my vacuum box attached thereto, ready to be lowered against the top of an empty ingot mold; Fig. 2 is a section taken in a plane parallel to Fig. 1, through a vertical axis of the teeming ladle, showing the empty ingot molds, the vacuum box in position thereon, and part of the ladle to which the box is fastened; Fig. 3 is a section, through Fig. 2, as indicated by the lines 33 of that figure; Fig. 4 is a transverse section through a vacuum box,.as indicated by lines 4-4 on Fig. 3, but showing a nozzle construction in place of the Pitot tubes of Figs. 2 and 3; Fig. 5 is a transverse section through a modified form of vacuum box, showing the same secured to a ladle and resting on the top of an ingot molcl; Fig. 6 is a transverse section'through the construction of Fig. 5, as indicated by the line 6-6 on Fig. 5; Fig. 7 is a horizontal section through the modification of Fig. 6, as indicated by the line 1-! on that figure.

The so-called vacuum box employed in the practice of my invention is preferably carried on the underside of the teeming ladle and surrounds the lower end of the nozzle used to pour the metal into the molds. This vacuum box as shown in Fig. 1 is fastened to the underside of a teeeming ladle L, which in turn is suspended by a pair of books h from an overhead traveling crane. Lying beneath the travel of the overhead crane is a track T adapted to carry a series of cars 0 forming a train of molds, two of which molds M may be carried by each car. When the pouring operation takes place, either the ladle L may be moved by the crane along the train of mold cars or the train itself may be moved underneath the ladle, permitting successive ingot molds to be poured.

The desired degree of vacuum may be obtained by means of an air column acting through a Venturi nozzle or by the use of a Pitot tube.- It is also possible to practice my invention by the use of a direct suction pump mechanism, by means of which the air is directly withdrawn from within the space to be evacuated. In either case it is desirable that suitable pumping mechanism be provided adapted to be moved when the ladle is moved in order to maintain a connection continually with the box Ill. Such a pumping apparatus either for force pumping or for use with a vacuum pump may be mounted on a suitable truck t adapted to be moved along the pouring floor with the ladle. On the truck t is carried a pump P preferably of the reciprocating type and which is driven by an electric motor. Since the action of the pump is pulsating, a storage tank S is provided to permit a constant flow of air through a suitable hose H to the vacuum box it]. If the modification of Figs. 5, 6 and 7 is used, the hose H will be used to transmit gas to the pump P by means of which direct evacuation of the ingot mold is produced without the necessity for the storage tank S.

In the preferred form of construction my vacuum box I 0 as shown in Fig. 2, comprises a somewhat flat rectangular metal chamber open at the top and bottom. The sides of this chamber are formed of steel plates l2, riveted along their corners to form a hollow rectangle, and having at their tops overlying flanges M by means of which the box is bolted or otherwise rigidly fastened to the underside of a ladle L in such manner that a. substantially air-tight seal is provided ad- .jacent the flanges l4. At their lower ends each steel plate I2 is flanged inwardly as at l6 to provide a support for the fire brick lining l5 which surrounds the inside of the entire four sides of the box l0, thus protecting the same from the ravages of the heat given off by the molten metal when poured and saving the same from the spattering action of such metal.

As shown in Fig. 2, the lower edges of the walls of the box In set into rabbets in the top edges of the molds thereby forming labyrinth joints for sealing the coacting edges.

A suitable pipe passes through the vacuum box ill to accommodate a column of air moving from the pump? through the hose H. As shown in Fig. 3, this pipe is rectangular in cross-section and is located adjacent a bottom corner of the vacuum box.

This pipe 20 is formed of a structural plate bent to the desired shape and welded or otherwise fastened along the joining seam to provide an air-tight construction. As shown in Fig. 2, this pipe passes entirely through the box In and 'may be secured thereto at the outer edges by angle members 2| fastened to the siding l2 of the box, as well as to the sides of the pipe 20. Within the confines of the box ill the pipe 20 is covered flared funnel 25, which, at one end, closely fits the outside of the pipe 20. This funnel decreases the pressure per unit area adjacent the region where the air column is discharged into the atmosphere, and thus avoids any danger which might result, should a powerful blast strike a workman in the vicinity.

A grill or screen 26 is provided adjacent the open end of the funnel 25, to prevent solid matter of appreciable size which may flnd its way into the pipe 20 from being discharged into the atmosphere. The screen is preferably made removable to permit cleaning of the pipe 20 and the funnel 2'5 when desired.

An opening 28 is provided in the central region of the lower sides of the pipe 20, through which the ingot mold is evacuated. Although merely flowing the air column past this opening will produce a considerable degree of vacuum, it is preferable that this be supplemented by a'nozzle action. To this end I have provided a Pitot tube 30, located in the opening 28 at the bottom of the pipe 20, and facing toward the discharge end of the pipe. This Pitot tube which is preferably circular in cross section is rigidly fastened to the pipe 20, by being fastened to downwardly turned flanges 3i formed when the opening 28 is cut in the bottom plate of the pipe.

Devices other than the Pitot tube 30 may be used to supplement the evacuating action induced by passing a column of air past the opening 28 of the pipe 20. For example, Fig. 4 shows a Venturi nozzle 33, circular in cross-section at its free end, and at its other end of a rectangular crosssection adapted to snugly embrace and be tightly fastened to the inside of the pipe 20 toward the intake end of the pipe from the opening 28. Air pumped through the pipe 20 from the pump P passes through the nozzle 33 and as it emerges therefrom induces a Venturi action causing air to be sucked through the opening 28 therebeneath, which tends to evacuate the interior of the ingot mold M over which the entire apparatus is seated.

When a Pitot tube 30 is used, the action is substantially the same since the passing of the column of air past the tube creates a region of vacuum adjacent the enclosed tube end which're suits in the partial evacuation of the ingot mold in the manner similar to that which results in the action of the Venturi nozzle.

A modification of the invention is shown in Figs. 5, 6 and 7, which operates by directly evacuating the interior of the ingot mold by means of a vacuum pump in contrast to, the preferred form of evacuation which results from passing a. column of air past a Pitot tube or other nozzle construction and thus secondarily creating the sucking action. In this. modification, a box 35, having outturned flanges 36 at the top and inturned flanges 31 at the bottom, corresponding to the members H and I6 of the preferred form, is shaped to form a rectangular box open at each end. The outturned flanges 36 are riveted or otherwise securely fastened to the underside of a ladle L in a position to enable the box to surround the discharge nozzle N of the ladle.

A suitable flrebrick lining 38 is provided for 15 the sides 35* and supported on the inturned flanges 31 of the bottom of the box. As shown in Fig. 5, a partition 40 is formed, dividing the box into two sections, the ends of the partition 40 terminating at flanges ll, which are riveted or otherwise securely fastened to adjacent faces of the sides 35a of the box. The lower ends of the partition 40 are cut into segments of flange;

alternate segments of which are bent horizontally on respective sides of the partition 40 to support fire brick lining 42 on each side thereof.

It will be noted that the partition 40 is so disposed within the vacuum box that one chamber is considerably smaller than the other. The smaller of these chambers is provided with an exhaust pipe 50, securely fastened to the sides of the box and communicating with the interior through its opening ii in the box and the thebrick. This pipe 60 extends outwardly horizontally and is provided with a screen 52, to bar the egress of solid particles from within the chamber to be evacuated.

The screen 52 is made removable to readily permit the cleaning of the pipe 50. At its free end, this pipe 50 is providedwith a coupling of any well known form, to allow a suction hose to be fastened thereto and yet be readily removable when desired.

When this modification of my invention is used, a hose is fastened to the bayonet coupling of the pipe 50, which leads to a vacuum pump used to produce the degree of vacuum desired within the ingot mold chamber. If desired, a baiile plate or similar construction may be interposed between the pipe 50 and the vacuum pump to prevent any solid matter from entering the pump chamber.

As heretofore mentioned, the eifectual operation of my invention depends upon obtaining as nearly as practicable an air-tight seal between the various devices combining to form an enclosed chamber. Where the vacuum box is secured to the ladle in a permanent manner, this seal may readily be made air-tight. If the siding forming the ingot mold is removable from the bottom, a seal here is readily eflected as soon as the hot metal starts to accumulate in the bottom of the mold. In practice it has been found that by employing a rabbeted upper end in the ingot mold M as shown in Fig. 2, into which the vacuum box it may closely fit, it has been possible to provide an effectual seal at this point. If, for any reason it should be desired to form a complete seal for the entire chamber, this may be accomplished by packing the junction of the various parts, as for instance, the junction of the vacuum box and the top of the ingot mold, with soft fire clay dd.

Attention is called to the fact that in the preferred form of construction the pipe til is located adjacent a corner of the vacuum box, as shown in Fig. 3, while in the modified construction the pipe at enters the vacuum box adjacent the corner and is separated from the main chamber by a partition til. These fluid outlets have been placed in such a position to insure that they shall not interfere with a stream of metal dropping through the vacuum box from the ladle into the ingot mold, but that at all times the main stream of metal shall drop unimpeded from the nozzle to the ingot mold.

It is not necessary to make the vacuum box removable from the underside of the ladle, since the latter is never deposited directly on the ground, but rather is supported on a pair of trunnions, except during such period when various repairs are being made to it, at which time the vacuum box can be removed if desired.

In operation, my invention may be used to effect the evacuation of ingot molds at various times. Preferably I choose to begin the evacuation before any metal is poured into the mold and continue the evacuation for some time after the mold has been completely filled. This, however, is a matter of expediency and under certain conditions it might be found preferable to vary the evacuating action for a longer or shorter period of time, as best determined by the requirements of a particular case, and depending upon what sort of metal was cast with the aid of the apparatus and the method embodied in my invention.

When an induced vacuum is created by pumping a fluid column past an orifice, as in Fig. 2,

the pressure per square inch may run as high as the mechanical features of the apparatus will permit, such pressure always being governed by the degree of vacuum desired since the higher the pressure in the pipe 20, the lower will be the pressure in the mold. When a direct vacuum pump is used, as in Figs. 5, 6 and 7, the size of pump is governed directly by the degree of evacuation to be obtained. The higher the degree of vacuum employed, the freer the casting will be from defects, such as pipe and blow holes.

It will be seen from the foregoing description and from the drawings that I have provided a novel means for evacuating the interior of an ingot mold during the pourihg operation. This evacuation may be performed in various ways, two of which I have illustrated. In one of these ways I draw the air directly from the interior of the ingot mold by the vacuum pump. -In another illustrated method of operation I produce the desired evacuation by the suction created in passing a column of air over an opening leading to the interior of the ingot mold. My invention comprises suitable apparatus for evacuating the desired mold, as well as the method by which such evacuation results, and it will be seen that by practicing my invention I am able to produce castings of steel or various other metals which shall be free from the defects now encountered, namely, the objectionable flaws, such as blow holes, fissures and pipe, which, at present, are encountered when various metals are cast in molds.

I claim:

1. The combination of a closed container open on one face, said open face being adapted to register with the open end of an ingot mold, a pipe passing through said container, an opening in said pipe communicating with the interior of said ingot mold, and means to partially evacuate the interior of said ingot mold through said pipe by passing a fluid stream through said pipe in addition to the stream of air being evacuated.

' 2. The combination of a closed container with an open face adapted to register with the open end of an ingot mold, a pipe passing completely through said container, an opening in said pipe communicating with the interior of said ingot mold, means to produce a moving column of fluid in said pipe, whereby gases within said ingot mold may be withdrawn therefrom through the opening in said pipe.

3. A container of the class described, adapted to overlie an ingot mold, a pipe passing completely through said container, means to create a moving column of air through said pipe, 2. restriction in said pipe, an opening in the pipe adjacent the restriction and communicating with the interior of said ingot mold, whereby the gases within said mold may be partially evacuated when said column of air moves through the restriction.

4. A container of the class described, adapted to overlie an ingot mold, a pipe passing completely through said container, means to create a moving column of fluid through said pipe, a Pitot tube within said pipe communicating with the interior of said ingot mold, whereby the gases within said mold may be partially: evacuated when said column of fluid moves past the Pitot tube.

5. A container of the class described, adapted to overlie an ingot mold, a pipe passing completely through said container, means to create a moving column of fluid through said pipe, a convergent nozzle in said pipe, an opening in said pipe adjacent the nozzle and communicating with the interior of the mold, whereby the gases within said mold may be partially evacuated when the column of fluid moves past the nozzle.

6. In a device of the class described, a rectangular box comprising sides lined with fire brick, a pipe passing through said box sides, an opening in said pipe on the bottom sidethereof, a converging nozzle extending across the opening in the bottom thereof, and guiding substantially the entire air column through its converged end, an open end of said box being adapted to register with the top of an ingot mold, whereby the interior of the same may be partially evacuated when an'air column is passed through the pipe and the nozzle therein.

'7. In a device of the class described, a rectangular box comprising four sides lined with fire brick, outwardly extending flanges adjacent the top of said sides for attachment to the underside of a teeming ladle, intumed flanges on the bottom of said sides to support the fire brick lining, a metal pipe passing through said box sides, fire brick lining surrounding said pipe, an opening in said pipe and said fire brick on the bottom side thereof adjacent the center and within the box, a Pitot tube extending within said tube and registering with the opening in the bottom thereof, a coupling on the intake end of said pipe for attachment of a hose leading to a pump, a funnel open at the flared end on the discharge end of said tube to substantially reduce the pressure of air per unit area therein before exhausting it to the atmosphere, a screen across the end of said flared portion, the open end of said box being adapted to register with the top of an ingot mold, whereby the interior of the same may be partially evacuated when an air column is passed through the pipe past the Pitot tube.

8. The combination of a structure having side walls and adapted to be closed at both ends to create a substantially air-tight compartment, said compartment having an opening to permit the passage of fluid between said compartment and a mold adapted to receive molten material, a pipe passing through said compartment, means to produce a moving column of fluid in said pipe, whereby gas may be withdrawn from said mold through said compartment opening.

9. In combination with a ladle, a pouring box, the lower edge of which is adapted sealingly to contact with the top of a mold, said box comprising a lining of refractory material and a supporting casing for the lining having an inturned flange below said material and an outwardly turned flange adapted to secure the casing to the ladle, vacuum producing means operatively supported by the box and having an orifice communicating with the inside of it, and a guard of refractory material inside the box, carried thereby and arranged to prevent contact between the molten material, en route to the mold,'and said orifice.

GEORGE W. HAZEY.

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