US2785449A - Casting apparatus - Google Patents

Description

Mal'ch 19, 1957 c. wEssEL 2,785,449

CASTING APPARATUS Filed Aug. 17, 195s 2 sheets-snaai 1 6 63 -T-I 2 63 3T* Hyg March 19, 1957 c. wEssEL.

CASTING APPARATUS 2 Sheets-Sheet 2 Filed Aug. 17, 1953 lconditions of equilibrium prevail.

United States Patent O CASTING APPARATUS Carl Wessel, Los Angeles, Calif., assigner, by mesne assignments, to Automation-Engineering Corporation, Los Angeles, Calif., a corporation of Delaware Application August 17, 1953, Serial No. 374,493

3 Claims. (Cl. 22'79) My invention relates to methods of casting, and is particularly concerned with methods for producing better Vcastings and better metal stock, of a plurality of shapes,

more efficiently and economically.

My invention relates also to improvements in casting apparatus.

In the transformation of a piece of metal into a finished product, such transformation will consist of one simple and direct path of continuous development when Difficulties arise, and unsatisfactory end-products result, when such conditions of equilibrium are prevented, altered or disturbed in the conventional process of transforming apiece of :metal into a finished product.

In present day procedures, a large billet is cast; this nonhomogeneous casting is then subjected to long soaking periods. in order to bring the grain structure of this casting to a more closely packed form (kneading effect) yit is then either forged, rolled or extruded. Then, after .withingrains is created by the allowance of insuicient .time for diffusion of 4atoms between the portions that solidify first and those that solidify last, creating what is known as coringff Processes designed to overcome this nonhomogeneity, for example rolling, extruding, forging, initial or subsequent soaking, irl-between annealing, solution heat treatment, or combination of these, have been provided to date.

An example of one of the problems in present procedures is the fact that in an aluminum-copper composition the highest obtainable solution of copper therein is about 5.6 percent. Rejection of copper begins at 550 degrees centigrade and if the casting is left to cool at room temperature only .5 percent copper remains in solution and the resulting physical properties are unsatisfacto-ry. Thus present procedure requires that the casting be reheated to, and maintained for substantial periods at, 5750 degrees centigrade and a quenching step is then performed while the casting is at this temperature.

further agehardening step is normally then required, wherein the casting is subjected to temperatures of l5() to 200 degrees centigrade.

The present program requiring giant presses originated from the requirement of forging rolled or extruded shapes lin order to provide a structure which would be closer to the desired design of parts to be used incertain mech- ,i

2,785,449 Patented Mar. 19, 1957 ice anisrns, such as air craft. But the high draft necessary in such process indicates that such forging is not the complete answer to the requirement because it necessitates reworking of as much as close to percent of a forging to produce a satisfactory product.

For a more detailed understanding of the present invention, reference may be had to prior United States patents of the present inventor, said patents being numbered 2,287,848, 2,309,608, 2,333,286, 2,429,145, 2,429,146, 2,407,334, 2,411,176, and 2,474,963. In the structures and methods of these prior patents the mold temperatures have been controlled by the necessary refilling of the mold during a given time or cycle. While such methods and apparatus produced castings of heat treat alloys which kept the major components in a high solution, elimination of solution heat treatment was not entirely accomplished thereby. No definite temperature of the mold, at least in an amount necessary to obtain equilibrium of alloying structures, was reached sufficient to permit entire elimination of the customary solution heat treatment. It is one purpose of the present invention to eliminate the present process of `soaking the initial casting in preparation for subsequent further operations, also eliminated, such as rolling, extruding, impact extruding, forging, etc.

Another purpose is to produce castings which do not lose their shape during further processing and will :also maintain the same high physical properties required.

Another purpose is to provide a process and apparatus which will eliminate present solution heat treatment procedures and provide the proper temperature control of a piece of metal.

Another purpose is to provide a method and apparatus capable of producing castings of the very highest physical properties and characteristics and perfect homogeneity and equilibrium of structure.

Another purpose is to provide a casting method and apparatus which will produce a piece of metal in its final form, having the highest physical characteristics and without subjecting such to rolling, extruding, forging, initial or subsequent soaking, irl-between annealing, solution heat treatment, etc.

Another purpose is to provide an apparatus wherein means is provided to keep the temperature of a mold constant regardless of the number of castings made.

Another purpose is to provide a method of casting wherein the pouring speed of the metal may be selectively varied to correctly control the amount of metal entering the mold in predetermined proportion to thermal conductivity of said mold.

Another purpose is to provide a molten metal Crucible of novel design and having particular advantages in a casting apparatus.

Another purpose is to provide a casting apparatus having means effective to simplify and minimize the time required in changing of molds from one casting design to another.

Another purpose is to provide a casting apparatus employing the use of graphite molds.

Another purpose is to provide a method of casting wherein mold temperature may be maintained slightly above the point of highest solubility of at least one of the alloys in the metal to be cast.

Another purpose is to provide a method of casting 'of Figure 3.

whereby the casting is held in the mold a minimum length of time.

Other purposes will appear from time to time in the course of the specification and claims.

Referring now to the drawings:

Figure l is a side View of the apparatus;

Figure 2 is a view taken on a line 2--2 of Figure l;

Figure 3 is a side View, in partial cross section, taken on a line 3 3 of Figure 2 and on a slightly enlarged scale;

Figure 4 is a View taken on a line 4 4 of Figure 3;

Figure 5 is a View taken on a line 5-5 of Figure 3; and

Figure 6 is a side View `of the structure illustrated in Figure 3, illustrating the mold-temperature indicator and showing the molding apparatus in operative position.

Like parts are indicated by like symbols throughout the specification and drawings.

The apparatus of my invention may be simply described as one incorporating means, such as internally cast or specially attached calrods and a pyrometer, to maintain a -constant mold temperature, as required, and a ladle employing a one-piece crucible of novel design and arranged within a structure in such manner as to permit ythe envelopment thereof by a iiame entering the structure, the crucible and structure being so designed as to cause said dame to thereafter flow across the open top of the crucible and into the mold. The mold attaching means, whereby various molds may be employed and rapidly replaced, is a further element of my invention.

The method of my invention may be simply stated as one wherein molten metal is maintained at a prescribed temperature within a crucible by the continuous application of heat surrounding the crucible, said metal is then controllably poured into a mold the temperature of which is maintained through the combination of heat supplied at the entrance of the mold and heating means associated with the mold itself.

Referring now to Figure l, the numeral 1 illustrates a Vbase or pedestal adapted to pivotally support the casting apparatus, for example, by means of the trunnion generally indicated at 2. Indicated in its entirety by the numeral 3 is the ladle which is movably supported on the trunnion or bearing-,frame member 2. The ladle 3 is balanced with respect to the assembly of the entire structure so that it would be normally upheld in upright position as shown in Figures l and 2, even when the supply of molten 'metal in the ladle has been exhausted.

The ladle 3 may comprise a metal shell such as the shell 4, which may be box-like as illustrated or which may be cylindrical. The shell 4 may be lined with a layer of insulating material, such as the asbestos liner 5 covering the inner surface of its side wall and its bottom wall.

The asbestos lining 5 supports a second rigid lining 6 of a refractory material, such as a ceramic product adapted to withstand the melting temperatures to which the metal is to be subjected. The refractory material 6a which is supported by the bottom wall may have an upwardly directed enlargement or projection 7 generally centrally located thereon and adapted to supporta crucible 8 which will be later described in more detail. As shown in Figure 4, the refractory lining 6 may have outer walls paralleling those of the shell d and may have a central cylindrical well generally indicated as the space C.

The top wall of the shell 4 may be lined with a substantial thickness of refractory material 6b. This top wall mayhave a central portion of lesser extension than the bottom wall of the shell 4, the central portion thus terminating short of one side wall thereof, said side wall being shown at the right hand of Figure 3. A hinge 10 is provided in this top-Wall portion and door member 11 is hingedly supported thereon. The door member 11 carries a handle member 12. `and is lined with a mass of refractory material 6c as will be best noted from a View Rotation of the door 11 about the hinge 10 provides access to the well'C and directly to the inner 4area'of thecrucible 8.

The crucible ti, which may be generally circular in horizontal cross section, has a bottom wall 8a adapted to seat upon the enlarged refractory material position 7. As will be noted from Figure 3 the major portion of the crucible is of a lesser diameter than the Well C, thus providing a substantial hollow area completely surround ing the lower portion of the crucible. The crucible 8 has a horizontally extending shelf 9 which is of sufficient extension to reach within the refractory material 6 as at on.' and to terminate just beneath the inner rounded lower edge of the refractory material of the door 11. It will be understood vthat the refractory material is cut away 4to provide a seat for the outer edge of the shelf or lip 9, as illustrated in Figure 3. The generally cylindrical wall of the crucible 8 which is diametrically opposite the lip 9 extends upwardly substantially above the height of the lip 9 and said upstanding wall extends circumferentially about slightly more than half the circumference of the crucible. Thus an opening A into the crucible is 4provided, as best illustrated in Figure 3. The 'upstan'ding wall portion of the crucible 3 is indicated at 15. It will be seen from a View of Figure 3 that the wall portion 15 is upwardly and outwardly inclined to form a -trough or pouring spout 16 to cause that portion of the wall diametrically opposite lip 9 to contact and extend within the area of the refractory material 6 as illustrated at 6e. The hollow inner area of the crucible 8 is given the letter B.

It will be understood that the metal shell 4 must carry with it means for supporting a mold to be brought into communication with the molten metal and the crucible 8. While such mold supporting means may be located in a variety of positions on the shell 4, I illustrate a very satisfactory arrangement whereby the upper Wall and the side Wall of the shell opposite the door 11 each contain portions 2ii-21, upwardly and rearwardly bent, adapted to receive and secure a cross plate member 22.

It will be realized that whereas I have described and illustrated a practical and operative device, nevertheless, many changes may be made in the size, shape, number and disposition of parts without departing from the spirit of my invention. I, therefore, wish my description and drawings to be taken as in a broad sense illustrative or diagrammatic, rather than as limiting me to my precise showing.

Referring again to Figure l, 30 generally indicates a mechanism for supplying a flame to the ladle 3. The mechanism 3i) includes a exible hose and a hand-operated shuto valve the details of which do not constitute a portion of the present invention and will not be further described. 31 indicates the inner end of the pipe attached to the device 30 and having the chamfered endportion 32 from which the llame ejects. As will be best seen from a view of Figure 4 the pipe 31 enters the ladle 3 to one side thereof and the flame from the opening'32 enters the well area between the crucible 8 and the refractory material 6 at a point adjacent said refractory material. As best seen from a view of Figure 4 the refractory material 6 has a generally circular well into which the crucible 8 is placed and that the llame thus enters this well in a generally tangential course to the circumference thereof, resulting in an immediate ow of the flame in a circular path around the crucible 8.

The flame enters at the bottom of the well and rises as it travels in a circle around the crucible 8. When the flame reaches an area above the shelf 9 it is forced to flow across the molten metal in the crucible 8 and to enter a passage leading to the mold, as will be further described herein below.

40 indicates a generally tubular member having the `longitudinal opening or bore 41 and being secured to the plate 22 in any satisfactory manner, such as vby the annular iiange 42. The opening 41 is arranged at an angle to the spout or lip portion 16 and is adaptedfto `receive the iiame after it has passed over'the molten metalin the crucible 8. The tubular member 40 has in its lower wall the passage 50. While the passage 50 may be of varying diameters and may be more than one in number, `one passage 50 alone is illustrated in the drawings. As will be best seen in Figure 6 the passage 50 places in communication the inner area of the crucible 8 and a generally conically shaped opening 51 which is itself also in communication with the opening 41 in the member 40. The member 48 with its passages 41 and 50 may, for convenience, be considered an outlet member. A mold adapter member 52, carrying spaced bars 53, is secured to the plate 22 by bolts passed through the anges 54 of the adapter member. The adapter member is provided with a generally centrally disposed conical opening or bore 51 which is in communication at its inner end with the outlet member 44B and at its outer end with a mold member 60, the latter being removably secured to the adapter 52.

I provide particular means whereby mold members may be removably secured to the casting device. Considering Figure 6, the mold is generally indicated at 60, the particular mold shown herein being composed of two parts 60a and 60h as illustrated in Figure 5. Each of the mold members 60a-60b has the apertures 64 extending therethrough. Tension members 61 extend through the apertures 64 and the adapter member 52. 63 indicates spacers permitting use of rods 61 with varied mold sizes.

70 generally indicates one of a set of two calrods, one of which is cast integrally with each of the mold members Gila-60h. Each calrod has its ends extending slightly outwardly from the mold member and these calrod ends are connected by the wires 71-71a to the pyrometer generally indicated at 72. 75 indicates a temperature pick-up, which may be of the thermocouple type, and which may be connected by the wires 76 to the member 72. The indicator 80 is connected by appropriate mechanism to the temperature pick-up 75 and is thereby caused to move across the scale 81 to indicate the temperature of the mold at any given moment. An indicator 82 is likewise adapted to move across the scale 81 to set and control the temperature of the calrod 70 and thus of the mold. Thus the operator is provided with a rapid visual indication of both the actual and desired temperature of the mold 60, i. e., when the indicators 80 and 82 are in alignment across the scale 81 the actual and desired temperatures of the mold member 60 are identical.

The method of my invention includes the maintenance of a supply of molten metal in the space B of the crucible 8 and the continuous application of heat around the outer wall of the Crucible 8, the said heat being applied also across the top of the molten metal and into the mold opening. The mechanism may be then tilted to cause the molten metal to flow through the aperture or apertures 50 at a controlled rate and into the mold, the temperature of which, in accordance with my method, is maintained at the desired level throughout the casting operation.

The use and operation of my invention are as follows:

A batch of molten metal, from which all dross and scum have been removed in the furnace, is applied to the crucible 8, so far as possible without exposure to the air. A deoxidizer compound, as desired may be kept on top of the charge of molten metal to prevent air contamination. A iiame is maintained constant in the well C surrounding the crucible 8 and flowing across the top of the molten metal therein into the mold opening. It will be noted that the mold and the ladle or crucible have their entry and discharge opening respectively smoothly tapered so that splashing and agitation of metal is maintained at a minimum during the pouring operation. To effect the pouring operation the entire structure 3 is gradually tilted or pivoted on its pivot 2 to cause the molten metal to flow from the Crucible 8 through the passage or passages 50, at a controlled rate, into the tapering conduit 51 and thereafter into the mold. Because of the arrangement of the mold with relation to the crucible 8 the molten metal will be caused to How from the restricted passage 50 along one wall of the mold initially, and as the pouring operation is continued the metal will, after reaching the outer limit of the mold begin to well up within the mold back toward the mold opening, thus forcing a substantial amount of the air withinv the mold backwardly out through the mold and into the space above the crucible 8.

Alter the mold has been lled it is maintained in the same position, with the metal of the crucible pressing into the mold, due to the head of metal in the Crucible, until the metal has solidified in the mold. There will be no aws or pipes nor will the casting: be .subjected to strange or unequal contractions. The entire mold will be filled and the casting will correspond more closely to the shape of the mold than with the method of the prior art.

During the entire operation the mold is continuously heated by a combination of the heat from the flame flowing across the molten metal toward the mold opening and by the heat engendered within the mold halves by the calrods 70. Thus the entire mold is maintained at a set temperature and the problems arising within the prior art, whereby the end farthest from the filling end of the mold is the coolest and a heat gradient extends from the metal-receiving end of the mold outward to the extreme end thereof, are obviated. Similarly, as the metal solidiiies the temperature of the mold may lbe gradually and smoothly reduced by a restriction upon the flame and a reduction of the temperature of the calrods, and thus the problem created within the prior art wherein the metal solidified, beginning at the extreme end of the mold away from the ladle and gradually toward the iilling opening of the mold, is also obviated.

I claim:

1. ln a casting apparatus, a housing, a refractory lining for said housing, said refractory lining defining a well within said housing, a molten metal crucible within said well and having its metal retaining portion of a diameter less than that of said well, means for supplying a flame to said Well adjacent a bottom portion thereof, said crucible having an upper portion formed and adapted to direct said flame across the surface of the metal contained therein, an outlet member secured to said housing, said outlet member having a iirst passage therethrough positioned to receive said llame after it has passed across said surface, said outlet member having a second separate passage positioned below said lrst passage to receive said molten metal in response to tilting of said housing, said first and second passages converging in the direction of discharge of molten metal through said outlet member.

2. A casting apparatus comprising a support, a housing tiltably mounted on said support, a well within said housing, a molten metal crucible positioned within said well, means on said housing for supplying a tiame to substantially the entire circumference of said crucible and across the surface of the metal contained therein, a pouring lip on said -crucible, an outlet member secured to said housing adjacent said pouring lip and above the surface of said metal when said housing is erected, a flame transmitting passage in said outlet member positioned to receive said flame after it has crossed the surface of said metal, a metal-directing passage in said outlet member, said metal-directing passage being positioned between said flame transmitting passage and the inner surface of said pouring lip.

3. A casting apparatus comprising a support, a housing tiltably mounted on said support, a well within said housing, a molten metal Crucible positioned within said well, means on said housing for supplying a flame to substantially the entire circumference of said crucible and across the surface of the metal contained therein, a pour- References Cited in the le of this Vpatent UNITED STATES PATENTS Schwartz Feb. 2, 1909 Bierbaum May 4, 1915 Soss May 24, 1921 Maughlin Oct. 12, 1926 .Huck Nov. 1, 19388 McWane Ian. 16, 1940 Husarek Nov. 17, 1942 Wessel Jan. 26, 1943 Wessel Oct. 14, 1947

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