US2448903A

US2448903A - Displacement type casting apparatus

Info

Publication number: US2448903A
Application number: US568253A
Authority: US
Inventors: Raymond J Miller
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-12-15
Filing date: 1944-12-15
Publication date: 1948-09-07
Anticipated expiration: 1965-09-07

Description

Sept. 7, 1948.

R. J. MILLER DISPLACEMENT TYPECASTING APPARATUS 2 Sheets-Sheet 1 Filed Dec. 15, 1944 Sept. 7, 1948. R. J. MILLER 2,448,903

DISPLACEMENT TYPE CASTING APPARATUS Filed Dec. 15, 1944 2 Sheets-Sheet 2 Fig INVENTOR.

ATIOQVEX Patented Sept. 7, 1948 UNITED STATES PATENT OFFICE DISPLACEMENT TYPE CASTING APPARATUS Raymond J. Miller, Detroit, Mich. Application December 15, 1944, Serial No. 568,253

I 2 Claims.

This invention relates to the casting of alloys or metals under conditions whereby entrained air and gases are removed from the casting cavity before and during the casting operation to reduce the resistance encountered in filling the mold, and to permit rapid and complete filling of the cas'ting 'cavity. An important phase of the invention relates to the casting of ordinarily inflammable alloys under non-oxidizing conditions whereby such alloys may be safely cast.

In casting operations as. heretofore performed it has been difficult to procure castings free from entrained gases because of the resistance encountered in displacing air and gases from the casting cavity. I have found that castings free from entrained gases can readily be formed if the casting cavity is evacuated before the casting operation is begun, and that rapid and complete filling of the mold is thereby assured.

Considerable difficulties have also been encoun-- tered in the castin of certain inflammable alloys such for example as magnesium because of the chemical reaction that takes place when the molten alloy contacts the oxygen of the atmosphere. It has been common practice to cast such alloys in the presence of sulphur to suppress the combustible characteristics of the molten alloy by the formation Of sulphur dioxide, These expedients have not been particularly satisfactory because it has been impossible to displace the sulphur dioxide from the casting cavity rapidly enough to insure complete filling of the mold under conditions whereby castings free from entrained gases are insured.

An object of this invention is to provide an improved method of casting whereby the casting cavity may be evacuated and, if desired, subjected to suction as the mold is filled to insure rapidand complete filling of the mold to provide castings free from entrained gases.

Another object of the invention resides in the provision of an improved method or molding whereby the casting cavity of a mold may be evacuated to remove oxygen, and molten alloy or metal may be introduced into the casting cavity by a displacement method under the pressure of an inert or non-oxidizing gas to assist in the complete filling of the mold under substantially non-oxidizing conditions.

A further object or the invention resides in the formation of a novel crucible and mold combination whereby oxygen may be displaced from the crucible and casting cavity of the mold by an inert or non-oxidizing gas, and molten alloy or metal may be displaced from the crucible by the 2 pressure of the inert gas to fill the casting cavity under non-oxidizing conditions.

A still further object of the invention is to provide an improved crucible whereby oxygen may be displaced from the crucible and the pressure of an inert or nan-oxidizing gas exerted therein to displace alley or metal from the crucible into a casting cavity of a mold associated with the crucible.

Yet another object or the invention is to provide an improved method of casting whereby the casting cavity is evacuated and is subjected to suction during the casting operation to provide a differential of fluid pressure to assist in the filling of the mold. 1

A further object resides in the development of a displacement method oi molding whereby molten alley or metal may be introduced into a cast ing cavity by a (inferential of fluid pressure resulting from the application of fluid pressure at the feeder and suction at the opposite end of the casting cavity.

Another object is to provide a mold having a casting cavity interposed between spaced ieeder and vent forming passages whereby the casting cavity may be" filled with an inert gas prior to the casting operation and wherein the vent passages become obstructed during'th'e casting operation to permit subjecting the casting to fluid pressure to assist in completely filling the mold.

A still further object is to provide a crucible wherein an alloy or metal may be melted in the presence of a non-oxidizing gas to prevent oxidation of the surface of the molten metal.

Still another object resides in the provision off an improved casting machine having cooperating crucible and mold members thatrma'y be 511% jected to the pressure of an inert gas to displace oxygen prior to the casting operation, and wherein the supply of inert gas to the mold may be interrupted simultaneously with an increase in the pressure of the gas on the crucible to displace molten alloy or metal from the crucible to the casting cavity of the mold.

A further object of the invention is to provide an improved casting machine capable of melting alloy or metal under non-oxidizing conditions, and evacuating oxygen from a casting cavity to permit the formation of castings free from entrained gases.

Another object of the invention resides in the formation of interconnected mold and crucible members wherein the mold may be subjected to suction to draw an inert gas into the crucible to.

2,44aoos displace oxygen from the crucible and casting cavity of the mold.

Other objects and advantages of this invention will be apparent from the following detailed description considered in connection with the accompanying drawings, submitted for purposes of illustration only and not intended to define the scope of the invention, reference being had for that purpose to thesubjoined claims.

In the drawings wherein similar reference characters refer to similar parts throughout the several views:

Fig. 1 is a longitudinal sectional view of a casting machine embodying the present invention.

, Fig, 2 is a longitudinal sectional view of a mold illustrating the formation of a match plate pattern.

Fig. 3 is a sectional view taken substantially on the staggered line 2-3 of Fig. 2 looking in the direction of the arrows.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of partsillustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring now more particularly to Fig. 1, it will be observed that spaced crucible and mold carrying members l8 and I2 are provided. The crucible i8 consists of a container l4 having a partition i 8 to divide the space within the container into an alloy or metal receiving chamber 18 and a feeder forming passage 28. The container l4 and partition l8 are preferably formed of non-conducting material such for example as a clay-graphite substance whereby alloy or metal 22 positioned in the chamber I8 may be heated electrically as by induction or high frequency electric current emanating from spaced coils 24 positioned around a portion of the container l4. The coils 24 are hollow as illustrated at 28 whereby any suitable cooling medium such for example as water may be circulated therethrough to prevent overheating of the coils 24.

The container I4 is preferably provided with a flange 28 adapted to receive a. fitting 88 to secure a cover plate 82 in place on the container as by means of screws 34. A gasket 38 formed of any suitable sealing material may be employed to seal the space between the top of the container I4 and the cover plate 82. The cover plate 82 has an opening 38 for the reception of the alloy or metal 22 to be cast, and the opening 88 may be closed by a cover plate 48 having a valve member 42 associated therewith.

The feeder passage 20 communicating with the chamber I8 is connected with a feeder passageway 44 formed between an upper wall of the cover plate 82 and a lower wall 48 of the cover plate 82 secured to the container I 4 by the fitting 88 as illustrated.

The mold receiving member l2 consists of cone and

drag portions

48 and 88 having suitable sealing means 52 and 84 such for example as rubber flanges adapted to aline to provide a fluid-tight seal between the cope and drag

mold receiving members

48 and 88. It will of course be apparent that any other type of sealing means may be employed. The bottom of the container.

l4 of the crucible l and the drag member 88 of the mold carrying member i2 are positioned on suitable supports in spaced relation so that the cope portion 48 of the mold carrying member l2 may be positioned on the drag portion 88 and the cover plate 32 may be assembled on the crucible and mold carrying members l8 and 42 as illustrated in Fig. 1.

The cope mold receiving member 48 is preferably provided with an angularly disposed flange 88 adapted to aline with and be secured to an oppositely disposed flange member -58 carried by the closure member 82 of the crucible iii. A liner preferably formed of non-conducting material such forexample as plaster or silicon, depending on whether low or high temperature melting alloys or metals are to be cast, is provided to form the feeder passage 44 interconnecting the feeder forming passage 44 with a downwardly extended liner 82 positioned in the cope mold receiving 'member 48. The angularly related surfaces of the

lines

80 and 82 abut to form a substantially fluid tight joint between the

members

88 and 88.

Spaced cope and drag molds 84 and 88 cooperate to provide a casting cavity 88 embodying the contour of any desired article to be cast. The cope and drag molds are each provided with a plurality of spaced openings 89 and 18 to provide molds of honeycomb-like structure whereby moisture may be readily removed from the mold during the drying or curing operation. The cope mold 84 has a feeder passage 12 alined with the feeder passage in the liner 82, and communicates with the casting cavity 88 through a passage l4. a

One or more vent passages 18 may communicate' with spaced portions of the casting cavity 88 to permit air or gases to be removed from the casting cavity. Filter members such for example as plugs of sintered material 18 may be positioned in contoured recesses 18 formed adjacent the surface of one or both of the molds 84 and 88 to permit air or gases to flow therethrough from the casting cavity 88. Suitable spacers 88 are positioned in the drag and cope

mold receiving members

88 and 48 to align the drag and cope molds 88 and 84 in suitable spaced relation in the

mold receiving members

48 and 88.

Means may be provided to displace oxygen from the casting cavity of the mold and the space within the crucible. This may be accomplished by evacuating the casting cavity and crucible or by introducing an inert or non-oxidizing gas into the crucible and casting cavity to wash the mold thereby insuring the removal of oxygen from the mold.

One desirable form of mold and crucible evacuating means comprises a conduit 82 projecting through one of the mold receiving members 48 or 58 in communication with a space 84 communicating with the casting cavity 88 through the vent passages 18 and filter members I8, and with the space [8 within the crucible through the feeder passages and valve mechanism associated therewith.

Spaced

mold alining members

88 and 88 are provided to insure accurate alignment of the cope and

drag molds

88 and 88 within the

mold receiving members

48 and 88. These aligning members may have oppositely extended conical shaped portions to project into oppositely disposed conical shaped holes formed in the contacting surfaces of the cope and drag molds 84 and 88 to shift the mold members longitudinally or laterally relative to each other to align the portions of the molds defining the casting cavity shift between-the mold sections. The moldsrecalving members 42 and have spaced dowel pins 00 carried for example by the cope mold tubing connected with a source of inert or nonoxidising gas such forexampleas helium, nitrogen or hydrogen projects into the valve member 42. The valve member may be actuated. by a lever I02 movable between closed, charging and casting positions I08, I04 and I08 respectively. A conduit I00 connected with the valve member 42 projects into the space I0 within the crucible II to direct the inert or non-oxidizing gas into the space within the crucible. A conduit H0 preferably formed of flexible tubing interconnects the space It within the crucible I0 with a chamber III communicating through an aperture II2 with the feeder passages 20, 44 and I2.

' A valve 4 having a plunger H8 is provided to control the aperture M2 under certain conditions oi operation. The valve H4 is controlled by a bell crank Ill pivotaliy. mounted on a bracket I20; and the crank is actuated by a link I22 connected with a crank I24 actuated by the lever I02 controlling the valve mechanism 42. when the lever I02 is in the charging position I04 the valve IIB is open as illustrated in Fig. 1,

' and when the lever I02 is moved to the casting position I00 the valve IN is moved to close the aperture I I2.

The operation of this device is as follows. Gone and drag molds having a casting cavity embodying the contour of the article to be cast are assembled in the mold receiving members 48 and It. The drag mold 80 may be positioned in the drag mold receiving member 50, and any cores or loose pieces required to cooperate with the mold members to shape the casting cavity positioned in place. The cone mold 64 may be positioned .on the dras mold 0B, and the cope mold receiving member 48 positioned in place, the sealing means 02 and 54 cooperating to securely seal the Joint between the mold receiving memiltoprovide acastingfree from oifsetting or at Illtoadmitinert here ll and 00. The cover plate 32 may then be secured in place by any suitable retaimng means. I! desired the cope mold receiving member 40 may remain secured to the closure member 32 of the crucible, and the drag mold receivingand the crucible I0 moved to align it in the desired operative relation. It will be understood that the crucible and mold carrying members 8 A or non-oxidizing as from the conduit IIII into the space It within the crucible above the alloy or metal 22 to be cast. The inert gas fills the space It in the crucible and flows through the conduit III and orifice II-2, feeder passages 20, 44 and 12 through the casting cavity 00 and out through the vent passage Il, diii'using through the filter members I0 to the space 04 between the molds and mold receiving members to the conduit 82. The entire space within the crucible and casting cavity is thus washed with the inert gas to prevent contaminatlon oi the molten alloy or metal duringthe time it is being melted in the crucible and introduced into the casting cavity to form the desired casting. Magnesium and other naturally inflammable alloys can readily be cast in this manner because oxygen is replaced by the inert gas and the possibility of combustion is thereby prevented.

The heating means, such for example as the electrical induction coils 24, is preferably actuated to melt the alloy or metal 22 after the air has been evacuated from the crucible. Where the induction heating mechanism is employed, high frequency current emanating from the coils 24 heats the alloy or metal 22.

When the alloy or metal is melted and has attained the desired pouring temperature, the lever I02 controlling the valve 42 is moved to the casting position illustrated at I00. The valve member 4 is moved by actuation of the lever I02 to project the plunger Ilt into the orifice II2 to close the communication between the feeder passages 20, 44 and I2 and the space It within the crucible above the alloy or metal 122. An increased how of inert or non-oxidizing gas then flows through the conduit I00, valve 42 and conduit I00 to subject the space I8 within the crucible abovethe alloy or metal 22 to increased pressure to force the alloy or metal out through the feeder passages 20, '44 and 12 to fill the casting cavity 68. The suction exerted through the conduit 02 withdraws the inert or non-oxidizing gas from the casting cavity when the lever I02 is moved to the casting position I00 accompanied by a closing of the valve IIB.

- it solidifies to seal of! the vent passages. -If de- "sired the pressure exerted by the inert or noncan be moved to operative relation by horizontal movement of one of the members relative to the other. I

A charge of alloy or metal 22 to be cast is introduced into the crucible and the closure 40 is positioned in place. The lever I02 controlling the gas inlet valve 42 is moved to the closed position illustrated at I03, and the suction inducing means is actuated to withdraw air through the conduit 82 to evacuate the casting cavity 88 and the space It within the crucible through the leader and vent passages.

when. the air has been evacuated, the lever M2 is moved to the charging position illustrated oxidizing -gas.may be maintained on the casting by leaving the lever I02 in .the casting position illustrated at I06.

After the casting has solidified, the

mold receiving members

40 and 50 may be separated and the molds It and it removed therefrom and broken up to release the casting.

If desired the lever I02 controlling the valve 42 may be moved from the casting position I06 to the charging position I04 after the mold has been filled, whereupon the pressure exerted on the alloy or metal 22 in the crucible will be reduced to equalize the level of alloy or metal in the crucible and in the feeder passage 20 to subject the casting to pressure through the feeder passages 20. 44 and I2. Y

Figs. 2 and 3 illustrate the formation of a match plate pattern I40 having spaced cope and drag pattern members I32 and I34 formed on opposite sides of the plate I30. The ends of the plate I30 are provided with outwardly extending projections I 36 and I38 adapted to provide handles whereby the match plate pattern may be readily handled. The feeder and vent forming passages I40 and I42 may be drilled out to provide apertures for the reception of dowel pins whereby cope and drag flasks may be allned on opposite sides of the match plate pattern I30.

It will be noted that a plurality of impressions I32 may be formed on the plate and that each impression I32 may be connected by feeder forming members I44 communicating with a centrally disposed main runner I46 toform their impressions in the mold investment used in subsequent molding or casting operations. The impressions I32 and I34 may be 01' the same or difierent articles and may be as closely spaced as is permissible in the particular casting operation for which the pattern equipment is intended.

Attention is directed to the fact that the suction means may be employed to evacuate the casting cavity without utilizing the inert or nonoxidizing gas to wash the casting cavity. By subjecting the casting cavity to suction before and during the casting operation, more rapid filling of the mold is possible because the molten alloy or metal does not encounter the resistance of entrained air or gases during the casting operation as the molten alloy or metal flows into the casting cavity.

The mold evacuating means may be employed with any method of casting because more rapid filling of the mold is insured since entrained air is removed from the casting cavity and the suction resulting from the evacuation of the mold draws the alloy or metal into the casting cavity.

It will also be apparent that it is unnecessary to use induction heating to melt the alloy or metal 22 within the crucible I since the alloy or metal can be melted in any of the known manners. My improved crucible embodying the displacement type of molding may be used with any type of mold.

I claim:

1. In a casting device having a crucible including a fluid tight closure, mold members associated with the crucible and including a casting cavity, feeder passage forming means interconnecting the space within the crucible with the casting cavity, fluid pressure supply means to subject the space within the crucible to the pressure of an inert non-oxidizing gas, valve means controlling said fluid pressure supply means and movable from closed through charging to a casting position to subject the space within the crucible to progressively increased pressure to displace a castable substance from the space within the crucible and force it through the feeder passage to the casting cavity when said valve means is in the casting position, vent forming means communicating with the casting cavity, auxiliary fluid pressure supply means interconnecting the space within the crucible with the feeder D831 sage to flush oxygen laden air from the casting cavity with inert; non-oxidizing gas from the space within the crucible, valve means controlling said auxiliary fluid pressure supply means and movable between closed and open positions, the combination therewith of motion transmitting means actuated by the first mentioned valve means to maintain the second mentioned valve means in the open position when the first mentioned valve means is in the closed and charging positions and to close the second mentioned valve means when the first mentioned valve means is in the casting position.

2. In a displacement type casting device having a crucible including a fiuid tight closure, a mold associated with the crucible and including a casting cavity, feeder forming means interconnecting the space within the crucible with the casting cavity, fluid supply means to subject the space within the crucible to the pressure of an inert non-oxidizing gas. valve means controlling said fluid supply means and movable from charging to casting positions to subject the space within the crucible to increased pressure, vent forming means communicating with the casting cavity at a point remote from the connection therewith of the feeder forming means, auxiliary fluid supply means communicating with the feeder forming means to flush the casting cavity with inert non-oxidizing gas to displace oxygen laden air therefrom, valve means controlling the auxiliary fluid supply means and movable between closed and open positions, the combination therewith of motion transmitting means actuated by the first mentioned valve means to maintain the second mentioned valve means in the open position when the flrst mentioned valve means is in the charging position and to close the second mentioned valve means when the first mentioned valve means is in the casting position.

RAYMOND J. MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 493,047 Simpson Mar. 7, 1893 807,072 Grimes et a1. Dec. 12, 1905 1,112,694 Grey Oct. 6, 1914 1,669,323 Brumm May 8, 1928 1,703,739 Klepsch Feb. 26, 1929 1,715,678 Schneider June 4, 1929 1,839,106 Loth Dec; 29, 1931 1,962,456 Myers June 12, 1934 2,024,854 George Dec. 17, 1935 2,036,496 Randolph Apr. 7, 1936 2,054,921 Betterton Sept. 22, 1936 2,125,080 Merrick July 26, 1938 2,140,607 Thompson Dec. 20, 1938 2,243,835 Brunner et al. June 3, 1941 2,359,524 Lane Oct, 3, 1944