US2082588A - Apparatus for producing slush castings - Google Patents

Description

June 1, 1937.

L. MENETREY APPARATUS FOR PRODUCING SLUSH CASTINGS Filed Jan. 4, 1936 .55

3 Shee ts-Sheet 1 INVENTOR.

- Lou/5 ME/VETEEX ZZ m,

ATTORNEY.

June 1, 1937. L. MENETRE Y APPARATUS FOR PRODUCING SLUSH GASTINGS Filed Jan. 4, 1936 5 Sheets-Sheet 2 INVENTOR, Lou/5 MENE TEE Y,

ATTORNEY.

June 1, 1937. MENETREY APPARATUS FOR PRODUCING SLUSHCASTINGS Filed Jan. 4, 1936 3 Sheets-Sheet 3 INVENTOR, A 00/5 ME/VETREX ATTORNEY.

Patented June 1, 1937 .5 STATES PATENT OFFlC Louis Menetrey, Alexandria, Ind, assignor to The- Mtntle p Company of America, Ghicago, ill., a corporation of Illinois Application Jan d, 1936, Serial No. 57,463

Claims.

y invention involves an improved means for ma castings by theslush method oi casting particularly where it is desired to so cast long and slender tubular structures, and where it is desired to produce cast structures with uniform wall thickness, and where it is desirable to use a minimum amount of casting metal in producing such structures wtih a specified strength of casting. i

li-slush casting is a hollow casting resulting from the tollowl series of events. Molten metal is introduced into a comparatively cool mold usually made of a material having a higher melting mint tn the casting metal, in sumcient quantity to completely fill the mold. The comparatively cool walls of the mold extract heat from the molten casting metal and cause such portions oi the casting metal as are in contact with the mold to freeze or solidify. This freezing of the molten metal extends farther and farther towards the center of the molten metal and in time the metal would solidify throughout and a solid casting would result. Instead of allowing themolten metal to remain in the mold long enough to solidiiy throughout, it is permitted to remain inst long enough to allow a wall of frozen or solidified casting metal to form to a desired thickness, whereupon the still liquid core or central portion of the casting metal is quickly flowed out of the mold. The hollow frozen shell in the mold, is the hollow casting referred to in this specification as a slush casting.

By my invention, 1 sheet the casting operation with the mold preferably'in vertical position, or substantially so, and I fill the mold cavity through the lower open end of the mold, the upper end of the moldheing open or suitably vented, to permit the casting metal to flow upward freely in the mold. When the mold is so filled with the casting metal, and a desired thickness of cast wall has chilled and set, I discharge the surplus molten metal that is still=in the mold, through the lower end thereof, leaving a tubular cast structure in the mold which has a substantially uniform thickness of wall, and contains no more metal than is necessary to impart to it the desired strength With my apparatus it is possible to produce castings from sluggish metal of superior strength and toughness; which metal has heretofore been considered unsuitable for slush casting pur ses because of its considerable viscosity when mo ten. By my invention, I have produced long slender spindles over fifty inches in length with portions of as small an outside diameter as three quarters of an inch, from white metal consisting of substantially e% of aluminum, 2% of copper and 94% of zinc. This is because with my apparatus it is possible to quickly fill the mold with the molten metal without splashing, cold shuts and the pocketing of air within the mold, and because the speed of evacuation of the surplus molten metal from within the mold can be definitely controlled so that the wall thickness of the castings can he held within desired limits.

My invention provides an apparatus which is not costly to'malse, is easily kept in order, and has no pump with a metallic piston or other moving part in contact with the molten metal, to contaminate said molten metal or to corrode and get out of order.

To force the casting metal to flow upward in the mold, I mount the mold preferably in vertical position, or substantially so, on the container or pot containing the supply of molten metal, which pot is tightly sealed to prevent gas leakage into or from the pot. The pot is kept hot by suitable means, and from the lower end of the mold, a pipe extends downward inside or the pot, nearly to the bottom thereof. To flow the molten metal upward through said pipe into the mold to fill the latter, I introduce a suitable gaseous medium under pressure into the pot, on top of the molten metal, such a pressure being used that it will balance the column of molten casting metal in the mold, when the top of the column is just above the mold cavity itself, the upper end of the mold being open and upwardly extended for that purpose. When the desired thickness of cast wall is formed in the mold, the gas supply to the pot is shut oil. the pressure in the pot is decreased and the surplus molten metal runs down from the mold into the pot.

The above and other objects of my invention will be best understood by reference to the accompanying drawings illustrating a preferred embodiment of the invention, in which- Fig. 1 illustrates diagrammatically in front elevation and partially in vertical, sectional elevation, the apparatus employed in carrying out my improved process;

Figs. 2, 3, and d are horizontal, sectional views to an enlarged scale, of parts of the structure shown in Fig. 1, taken respectively along lines 22, 3-3, and 4-4;

Fig. 5 shows in a view similar to Fig. 1, the apparatus employed in carrying out my said process, using a modified form of mold and mold support, this view being taken along the line 5-5 in Fig. 6.

Fig. 6 is a horizontal view to an enlarged scale of a part of the construction shown in Fig. 5, taken along the line 6-8;

Fig. 7 shows in a view similar to Fig. 1, in vertical, sectional view and to an enlarged scale, modified means for connecting the lower end of a mold to the container of the molten casting metal, and

Fig. 8 illustrates in vertical, sectional view and to an enlarged scale, the valve shown in Figs. 1 and 5 for controlling the gas pressure in the molten metal container.

Similar numerals refer to similar parts, throughout the several views.

As shown in Fig. 1, I illustrate a container or pot ill for holding molten casting metal, for example, white metal, which pot is provided with a tightly-fitting cover II to prevent leakage into and from said pot.

The pot I0 is surrounded by an enclosing metal wall I2, which, together with the cover II and the fire-proof floor I3 on which the wall I2 rests, form a compartment around the pot that receives the products of combustion from a burner I4 to keep the pot and its contents in a properlyheated condition, so that the contents of the pot, for example white metal, will be maintained in a properly fluid condition to flow into the mold.

The cover II has extending downward therefrom, a pipe I5, which terminates below the molten-metal level I6 and near the bottom of the pot, so that most of the molten metal may be forced upward into a mold I1, as required in the making of successive castings.

More than one pipe I5 as well as more than one mold may be employed if desired.

The upper end of the pipe I5 is flanged and supported in a recess in the cover II, in which position it is tightly held by a gasket I8 which is pressed against it by a ring I9. The ring I8 is provided with an inner and upwardly-diverging conical seat I9a, engaged by the similarlyformed lower end of the mold I1, to form a tight joint between the ring I9 and the mold I1.

The cover II has tightly secured to it the upper end of a tube 20 extending downward into the pot I0, said tube 20 being closed at its lower end and containing a thermo-couple 2I for operating the pyrometer 22, which indicates the temperature in the pot ID.

The cover II also has connected with it, a pipe 23 for supplying compressed air to the pot I8, which pipe is connected with a safety-valve 24 and a pressure gauge 25, said safety-valve 24 being set for the maximum air pressure to be developed in the pot during any particular casting operation, and the gauge 25 so connected that it indicates the air pressure in the pot at all times. The pipe 23 also connects with a three-way valve 26, which valve 28 is also connected with an air-supply pipe 21 and an exhaust pipe 28 opening to atmosphere, said valve 26 having an operating handle 29 which may be turned to upper, middle and lower operative positions. When in said upper position, as more clearly shown in Fig. 8, the pipes 23 and 28 are connected and the pipe 21 is closed. When said handle 28 is in its lower position, the pipes 23 and 21 are connected and the pipe 28 is closed, and when said handle is in a middle position, both of the pipes 21 and 28 are closed, thereby disconnecting both of said pipes from the pipe 23. As shown in Fig. 8, said valve 26 is of the plug type, and the plug 38 thereof is provid d P ug 38 in Fig. 8, being with a port 38a establishing the connections above described, the handle 28 in Fig. 1, and the shown in their middle positions.

The cover II is also provided with a removable screw-plug 3| to admit of the supplying of casting-metal to the pot III, as required.

The air supply pipe 21 is connected with a pressure gauge 32 and with the outlet of a. trap 33, the inlet of said trap being connected by a pipe 34 with the outlet of a pressure reducing valve 36 the inlet'of which is connected by a pipe 36 with any source of air under pressure, not shown. The valve 36 is set for any desired pressure to'be supplied through the trap 33 to the pipe 21, which pressure is shown on the gauge 32, and constitutes the source of air under pressure for communication to the pot I0 through the valve 28.

As shown in Fig. l, the mold I1 consists of two parts I11: and Nb, which are separable to permit the removal of the castings therefrom. Said mold is supported as follows: The mold part Ila, as shown in Fig. 2, is connected by screw studs 31 with a first flat bar 38, and the mold part I1!) is similarly connected by screw studs 39 with a second flat bar 40 similar to and substantially parallel with the bar 38 when the mold is closed. The bar 40 as shown in Fig. 1, is secured, at its lower end, to a bracket 4i having a pivotal connection at 42 with a first standard 43 mounted on the floor I3, which holds the supporting structure of the mold in such position that, whenthe mold is swung to its vertical position on its said pivotal connection 42, its lower end registers with and enters the ring I9 to tightly engage the seat I9a therein. A second standard 44 is mounted on the floor I3 to support the mold in its horizontal position shown in dotted lines, when it is opened to remove a casting therefrom.

The bar 38 has secured thereto a plurality of cross-bars 45. and the bar 48 has secured thereto a plurality of cross-bars 46 which, respectively, cooperate with each other to hinge the bar 38 to the bar 40. as shown in Fig. 4, each of the bars 45 being bent at substantially a right angle at the flatv bar 38 and resting against the edges of the bars 38 and 48 and extending through a slot therefor in the end of the corresponding'bar 46.-

A pin 41 extends through the slotted end of the bar 46 and through a longitudinal slot therefor in the end of the bar 45,- which permits the flat bar 38 to be lifted from the bar 48 a suflicient distance to disengage the dowel pins I1c of the mold I1, before the pin 41 acts as a hinge connection between the bars 45 and 46, at which time the flat bar 38 may be swung around the several pins 41, carrying the section I1a with it, to open the mold.

The bar 38 has secured thereto a plurality of spaced cross-bars 48, and the bar 40' has secured thereto a similar plurality of spaced cross-bars 49. As clearly shown in Fig. 3, each of the bars 48 and 49 extends beyond the edges of the corresponding flat bar 38 or 48, and is slotted at its ends. Each of the bars 49 has pivotally connected in each of its s otted ends at 50, one end of a link 5|. The two links extend through the slotted ends of the corresponding cross-bar 48 and have pivotally connected with their ends at 52, slotted clamping members 53 having camshaped ends engaging the end portions of the said cross-bar 48, to tightly press the mold sections Ila and Ill) together, when said clamping members are first turned to release the pressure exerted by them on the cross bars 48, and said links are then turned on their pivotal connections 50 to free thebars 48, so that the parts of the mold can be separated from each other.

Near its upper end, as shown in Fig. 1, the flat bar All, has secured thereto near its upper end, a cross-bar t extending substantially at each end beyond the flat bar so, as shown -in Fig. 2, to serve as handles 66a, in moving the mold and its supporting bars from. one position to the other. The flat bars 38 and 40 carry small pipes 56 along their inner surfaces, by connecting clips 56- as shown in Fig. 2, said pipes 55 being provided throughout their lengths with small apertures 55 a opening towards the mold ll, said pipes being connected at their ends near the bracket 4|, with flexible tubes 57! extending to any suitable source of air under pressure, to blow cooling air against the mold.

In Fig. 5, 1 illustrate a modified form of mold support. In this case, the cover H] has secured thereto a flanged tubular member 58 to press the gasket it tightly against the upper flanged end of the pipe l5, said member having a 'disk 59 extending horizontally from its upper portion to support a mold 6t. Said mold is in two parts having ears 5i and 62 extending, respectively,

from them at their adjacent hinge edges, through which a hinge rod 63 extends vertically to connect the mold parts, and to permit the mold to.

be opened and closed while resting on the disk 59. The opposite edges of the mold parts are also, re-

spectively, provided with cars 66 and 65, having tapered bores extending vertically through them and in alignment with each other when the mold is tightly closed, to receive a removable and taperedlocking rod as.

The parts just described are more clearly shown in Fig. 6, in which the mold parts 60a and tub of the mold 50, are provided with handles er and as, respectively, to facilitate opening and closing the mold. The disk 59, as shown in Fig. 5, is provided with a tubular extension 59a, extending upward therefrom, in line with and continuing the bore in the member 58 to the upper end of said extension, said extension 59a being provided with an outwardly-extending flange 5% having an inclined lower face 590, as a result of which the upper face and the lower face of said flange 59b, diverge from each other towards the axis of the extension 5911;. The lower portion of the mold 6b is counterbored to snugly fit the outer side and end surfaces of the extension 59a and of its flange 5%, as a result of which a wedging action on the mold occurs between the lower facethe pipe I5, said cavity having an open passage way Std extending from it to the upper end of the mold.

In certain forms of molds sluggish casting metal will not fill out the sharp edges and details of the mold unless pressure is applied to the liquid metal to force it into intimate contact with the mold. The upwardly extending passageway 60d may obviously be extended as far as circumstances require in order that the pressure resulting from this excess height of molten metal above .the mold will furnish the desired. pressure in the mold. It will be understood that the upper passageway Gfld may be either an integral part of the mold structure or it may be an attachment to the mold forming a. non-leaking Joint where it attaches to the mold. It will also be understood that an alternative method of exerting additional pressure on the metal in the mold, would be to plug the upper end of the passageway 60d after the -mold is filled, and then exert greater pressure on the metal in the container below, and removing the plug during the evacuation of the surplus molten metal from the mold.

The upper end of the bore in the extension 59a, is preferably provided with a small intumed flange 59d, to produce a tubular cast structure of minimum thickness at vthat'lcication, that will readily break to free the casting in the mold from any casting metal remaining in the upper.

end of the extension 59a, when themold is opened to remove a casting therefrom. A slmilar result is secured with the mold ll shown in Figs. 1 to i, inclusive, by means of the constricted lower end lld of the mold passageway shown in Fig. 1.

The mold Gil is adapted for use where the articles cast are of such size and form that the castings can be removed efiectively from the mold in vertical position.

The operation of making castings with the mold 30, as far as the handling of the casting metal is concerned, is the same as with the mold ll above described, and is as follows:

The pressure-reducing valve 35 is set to limit the air pressure in the pipes 3t and 271, to the maximum pressure that may be required to effectively operate thecasting machine, which pressure in said pipes 34, 27, at any time is shown by the gauge 32. The safety-valve 26 is then preferably adjusted for a pressure that will support a column of the molten casting metal, that is high enough to completely fill the mold and extend into the riser at theupper end oi the mold, but not high enough to flow'out from the upper end of the mold. The height of said column readily determines said pressure from the specific gravity of said molten casting metal, and the gauge 25 is a guide to the operator, since it shows the pressure of the air exerted on the surface of the molten casting metal in the pot N. Then, with the pyrometer 22 indicating proper temperature and fluidity of the molten casting metal, and with the mold il' or fill, as the case may be, in the casting position above described, the valve handle 29 is moved from its middle position to its lower position, supplying air under pressure from the pipe 21 to the pipe 23, to force the molten casting metal from the pot Ill and upward through the pipe l5 into the mold and to a height completely filling the mold cavity and extending somewhat above said cavity. The handle 29 is then moved back to its middle position, interrupting communication between the pipe 23 and either of the pipes 21 and 28, and either by holding the handle 29 in its said middle position, or by holding it in its lower position communicating air under pressure to the pot H), for a brief interval, a desired thickness of wall of the casting metal is chilled and set against the mold, after which, the handle 29 is moved to its upper position thereby closing the pipe 21 and reducing to atmospheric pressure the air pressure in the pot l through the pipes 23 and 28, for which condition the still molten metal in the mold is instantly drained therefrom through the pipe I! into the' pot l0, leaving a hollow casting in the mold with a desired thickness of wall. The mold is then opened as above described, the casting is removed, and the mold is again placed in casting position, ready to make the next casting.

Theapparatus and process described have important advantages as follows: Successive castings have a uniform wall thickness, and there is no excessive wall thickness at any point, thus producing castings of desired strength with a minimum amount of casting metal. Again, the casting metal is supplied to the mold from below the surface of the molten casting metal in the pot l0, thus avoiding putting into the mold any impurities or oxides that may be floating on the molten metal in said pot i0, and insuring that each casting shall consist only of pure casting metal. Again, there is no agitation or disturbance of the molten casting metal in the pot l0 during a casting operation, and no possibility of the inclusion of air in the casting metal flowed into the mold, as a result of which each casting is homogeneous throughout and contains no air bubbles or cold shuts resulting from included air, and the casting is stronger for the same weight than where the casting metal is impure and is not of uniform texture throughout the casting. A further advantage is that, as a result of the casting metal being pure and entirely free from included air and the undesirable results thereof, the surfaces of the castings are substantially perfect imprints of the mold surfaces, as to form, detail and surface finish.

In Fig. 7, I illustrate a modified construction for seating a mold 69 on the cover II. In this case, the pipe la extending downward from the cover II, is provided with a flange I 5b in a. corresponding recess in the 'cover II, a gasket I 8a resting on and extending over the outer edge of said flange. The pipe i5a extends a small distance above the gasket IS, the inner edge of which it closely fits, and then converges upward and inward at I So, forming an upper conical surface engaging a similarly shaped surface 69a on the lower end of the mold 69. The inner edge I5d of the conical end portion l5c of the pipe, forms a break line in the casting, and in other respects, the pipe I5a is the same and serves the same purpose as the pipe l5 above described. The gasket la and the flange l5b are held tightly against the cover i I, by a ring |9a which closely flts the short straight portion of the pipe l5a above the flange I512, above which, the ring is provided with a downwardly converging coni- "cal seat engaging a similarly shaped surface 6% on the lower end of the mold E9. The construction described, positively centers the lower end of the mold 69 around the upper end of the pipe i5a, and provides a double conical seat for the mold end, which is desirable in some cases, for example, where castings of considerable height are made, and the fit of the lower end of the mold must withstand considerable pressure. In other respects the mold 69 is the same as the mold i1 and is operated in the same manner.

It will be understood that other gases than air may be used, particularly where the casting metal in its molten condition, oxidizes readily in the presence of oxygen or air, in which case, an inert gas may be used, for example, nitrogen or carbon dioxide.

It will be understood that I do not limit myself to white metal as the casting metal employed in carrying out my invention, as I may use any alloy or metal that can be made to flow upward into the mold by gaseous pressure in the manner described. In this way, I may produce pipes of any such metal or alloy, and furthermore, I may make use of pipes, whether produced by the present invention or not, as the molds described and coat them internally with any such metal or alloy.

While I have shown my invention in the particular embodiment above described, it will be understood that I do not limit myself thereto. as I may employ equivalents known to the art at the time of the filing of this application, without departing from the scope of the appended claims.

Having thus described my invention, what I claim is:

1. Apparatus of the class described, including in combination a container for molten casting metal, said container having an opening for communication with the molten metal, an open-ended mold mounted for communication with said container opening, means for producing pressure on the molten metal limited to an amount which will flow molten metal into said mold without overflowing it, and means for reducing the pressure on said molten metal.

2. Apparatus of the class described, including in combination a container for molten casting metal, said container having an opening for com.- munication with the molten metal, an open-' ended mold mounted for communication with said container opening, means for producing gaseous pressure on the molten metal limited to an amount which will flow molten metal into said mold without overflowing it, and valve mechanism for reducing the pressure on said molten metal.

3. Apparatus of the class described, including in combination a container for molten casting metal, said container having an opening for communication with the molten metal, means for supporting a pipe vertically for communication with said container opening, means for producing pressure on the molten metal limited to an amount which will flow molten metal into said pipe without overflowing it, and means for reducing the pressure on said molten metal.

4. Apparatus of the class described, including in combination a container for molten casting metal, said container having an opening for communication with the molten metal, means for supporting a pipe vertically for communication with said container opening, means for producing gaseous pressure on the molten metal limited to an amount which will flow molten metal into said pipe without overflowing it, and valve mechanism for reducing the pressure on said molten metal.

5. Apparatus of the class described, including in combination a container for molten casting metal, said container having an opening for communication with the molten metal, an openended mold mounted for communication with said container opening, means for producing pressure on the molten metal limited to an amount which will flow molten metal into said mold without overflowing it, automatic pressurerelief means operative at pressures greater than said limited pressure to restrict the pressure on said molten metal to said limited amount, and

. means for reducing the pressure on said molten metal.

6. Apparatus of the class 'described, including in combination a container for molten casting metal, said container having an opening for communication with the molten metal, an openended mold mounted for communication with said container opening-means for producing gaseous pressure on the molten metal limited to an amount which will flow molten metal into said mold without overflowing it, automatic pressure-relief means operative at pressures greater than said limited pressure to restrict the pressure on, said molten metal to said limited amount, and valve mechanism for reducing the pressure on said molten metal.

7. Apparatus of the class described, including in combination a container for molten casting metal, said container having an opening for communication with the molten metal, means for supporting a pipe vertically for communication with said container opening, means for producing pressure on the molten metal limited to an amount which will flow molten metal into said pipe without overflowing it, automatic pressure-relief means operative at pressures greater than said limited pressure to restrict the metal, said container having an opening for' communication with the molten metal, means for supporting a pipe vertically for communication with said container opening, means for producing gaseous pressure on the molten metal limited to an amount which will flow molten metal into said pipe without overflowing it, automatic pressure-relief means operative at pressures greater than said limited pressure to restrict the pressure on said molten metal to said limited amount, and valve mechanism for reducing the pressure on said molten metal.

9. Apparatus ot the class described, including in combination a container for molten casting metal, said container having an opening for" communication with the molten metal, an openended mold mounted for communication with said container opening, means for producing.

metal, said container having an opening for communication with the molten metal, means for supporting a pipe vertically for communication with said container opening, means for producing pressure on the molten metal limited to an amount which willflow moltenmetal into said pipe without overflowing it, and means for reducing the' pressure on said molten metal, said pipe beingmovable from said container opening, there being all}: at said container opening extending into and facilitating separation of the cast metal at said lip by movement of said pipe away from said container opening.

LOUIS MENE'I'REY.

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