US2716790A

US2716790A - Apparatus for casting metallic articles

Info

Publication number: US2716790A
Application number: US225949A
Authority: US
Inventors: Joseph B Brennan
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-05-12
Filing date: 1951-05-12
Publication date: 1955-09-06
Anticipated expiration: 1972-09-06

Description

Sept 5 1955 J. B. BRENNN APPARATUS FOR CASTING METALLIC ARTICLES IN V EN TOR.

Filed May l2 APPARATUS FOR CASTING METALLIC ARTICLES Joseph B. Brennan, Cleveland, Ohio Application May 12, 1951, Serial No. 225,949

6 Claims. (Cl. 22-73) The present invention relates generally as indicated to an apparatus for casting, the present application being a continuation-impart of my copending application Serial No. 202,707, tiled December 26, 1950.

It is one object of this invention to provide an apparatus for economically, rapidly, and accurately producing, either continuously or successively, castings or laminated products in which the cast material is applied to a liner or the like in the mold cavity.

Another object of this invention is to provide a casting apparatus which involves relative movement of molten material supply means and mold-cavity forming means for bringing the latter into communication with a pool of molten material in the former while the material is under the influence of a vacuum, whereby air and gases are withdrawn from the cavity to facilitate the flow of the molten metal thereinto.

It is another object of this invention to provide a casting apparatus in which the mold cavity is successively communicated with a vacuum chamber and with a molten material supply whereby the mold cavity is rst evacuated and then lled with the molten material.

Another object is to provide an apparatus for casting in which the molding material is effectively degassed and de-oxidated. n

Other objects and advantages will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. 1 is a vertical cross-sectional view of one form of apparatus constituting the present invention;

Fig. 2 is a fragmentary vertical section similar to Fig. l except illustrating a modication in the mold cavity forming means;

Fig. 3 is another fragmentary vertical cross-sectional view illustrating a still further modification in the mold cavity forming means; and

Fig. 4 is a transverse cross-sectional View taken substantially along the line 4 4, Fig. 3.

As illustrated in Fig. 1, the apparatus comprises a receptacle 1 of graphite or the like heated as by means of the high frequency heating coils 2 therearound, said receptacle being adapted to receive therein a quantity of molten material 3 therein either supplied intermittently or at a desired uniform rate as from a spiral trough 4 leading to the receptacle from a suitable supply source and having associated therewith a heating coil 5, or, if desired, the material 3 to be cast may be supplied to the receptacle 1 in solid form for melting in the trough or receptacle by the heat supplied from the

heating coils

2 and 5. The chamber 6 defined above the level of the lni'ted States Patent O molten material 3 in said receptacle 1 is evacuated and maintained at a desired negative pressure as by means of the conduit 7 which leads to a suitable vacuum source, and, if desired, means may be provided on said receptacle 1 for introducing an inert atmosphere into the chamber whereby to prevent oxidation or deterioration of the molten material 3 therein. v

The chamber 6 aforesaid may be defined by bell-shaped parts 3 and 9 of which the latter preferably surrounds the receptacle 1 so that the exterior of said receptacle is not exposed to the atmosphere, said parts 8 and 9 being made from heat-resistant glass, aluminum oxide, silicon carbide, or equivalent material.

The spiral trough 4 is so formed that the material llows as a thin layer therealong and as shown said trough may have projections to produce a sort of weir which would expose the molding material, such as copper, for example, to the graphite of which the trough is preferably made. By so exposing the molten material to the vacuum, degassing and deoxidation is effected very effectively. Of course, a gas permeable carbon or like tube may be substituted for the trough 4 to spread out the molding material after it is introduced into the vacuum chamber.

While the

heating coils

2 and 5 are herein shown within the parts 8 and 9 surrounding the receptacle 1 and trough 4, either one or both may be disposed exteriorly of said parts 8 or 9 or located elsewhere within said parts other than in surrounding relation to the receptacle and the trough.

Extending vertically through said receptacle 1 is a guide tube 10 also of graphite or the like provided with cooling means 11 around the lower end thereof, a molten material inlet passage 12 below the level of the pool 3 in the receptacle and another passage 13 therethrough communicating with the vacuum chamber 6. The vacuum chamber cover 8 and receptacle 1 may be sealed to the guide tube 10 as by means of the conventional O-

rings

14 and 14A or other suitable packing means and the vacuum chamber part 9 is sealed to receptacle 1 by packing means 14B. Other packing rings 14C and 14D are disposed adjacent the upper and lower ends of said guide tube 10 operative to sealingly engage the molds 15 which are adapted to be moved downwardly through the guide 10, said molds 15 being inserted from the top and pushed downwardly to successively communicate the sprues 16 thereof with the

passages

13 and 12 in the guide 7 whereby as each mold 15 is positioned or passed in register with the passage 13, the mold cavity therein is evacuated and when each mold is in register with the passage 12, molten material will run into the evacuated cavity and thereby completely till the same. As the lled molds 15 pass downwardly, the material therein is cooled and solidified by the cooling means 11. It is to be noted that the sealing rings 15C and 14D adjacent the upper and lower ends of the guide 10 serve to cause the mold sections 1S therebetween to be pressed together as by the differential pressure, that is, atmospheric pressure acting on the end molds 15 and vacuum in between successive molds. Still

other packing rings

14A and 14B aforesaid are disposed between tube 10 and receptacle 1 and between said receptacle and the surrounding part 9. In order to permit use of packing rings of rubber-like material without melting, the parts are cored as at 10', 10, and 10"', 8', and 1' for circulation of coolant such as water.

The molds 15 just described may be of the type described in detail in the aforesaid copending application and as disclosed in my Patent No. 2,530,853, dated November 2l, 1950. Briey, however, the mold cavities may be formed in the molds by a process similar to the well known lost wax process, that is, embedding a meltable, combustible, or volatile model in a body of zirconium oxide, molding plaster, core sand, molding sand binders, carbon, or the like whereby upon disposal of the model, an accurate mold cavity is left without any parting lines or the like. Also, if desired, only a portion of the model may be made of such meltable, combustible, or volatile material whereby the non-meltable, non-combustible, or non-volatile portion of the model will remain in the mold body for casting of the molten material 3 thereagainst to form a laminated product.

In order to prevent exposure of the exterior surface of the upper end of tube 10 from the atmosphere and to effect a vacuum seal, a surrounding shell 17 may be provided made of a material the same or equivalent to that of the parts 8 and 9.

If desired, a vacuum bell may be provided on the bottom and top of tube 10 so that the casting could be removed while under vacuum and also so that the investment mold could be introduced while under vacuum.

It is to be understood that the particular mold 15 herein illustrated is to be regarded as merely typical and that, for example, adjacent molds 15 may define cavities therebetween with sprues and gates leading from the exterior of the molds to such cavities.

The modification of the invention illustrated in Fig. 2 comprises adjacent mold sections 20 adapted to be forced through a guide 21 and to have the molten material 22 owed into mold cavities defined between the adjacent and interfitting mold sections 20. Here again, the mold cavities successively communicate with the vacuum chamber 23 and with the pool of molten ma- .'f

terial 22 through the

passages

24 and 25 respectively, and as aforesaid any portion of the mold cavity may be lined with a material having a higher melting point than the temperature to which the molten pool 22 is heated whereby a laminated product may be produced.

In the modification of the invention illustrated in Figs. 3 and 4 the mold-cavity forming means comprises a rod-like member 30, either continuous or composed of adjacent sections and preferably of rectangular crosssection as shown and a guide 31 having sealed engagement with the rod-like member at the upper end. The guide 31 is formed with

passages

32 and 33 respectively communicating the mold cavities defined between the guide 31 and the rod member 30 with the vacuum chamber 34 and with the pool of molten material 35.

ln the particular assembly shown, the guide 31 is formed with a plurality of guide ribs 36 engaging the corners of the rod-like member 30 and thereby defining four strip-like cavities 37 whereby as the molten material ows into such cavities and solidilies therein as the rod 30 and adjacent material pass through the cooling zone of the guide 31, there will be produced a plurality of at strips which may be removed from the rodlike member 30 and further processed as by rolling or other treatment or simply coiled or otherwise bundled without such further treatment.

In the modification illustrated in Fig. 3 the rod-like member 3i) may be of any desired cross-section shape and if desired the molten material 35 may be cast therearound as a continuous sleeve or sheath and then stripped from the rod-like member as disclosed in my copending application Serial No. 147,466, filed February 18, 1950. ln this connection it is to be noted further that, if desired, the cast sheath may become a permanent part of the rod-like member 3G, thereby forming `a laminated product.

In the forms of the apparatus shown in Figs. 2 `and 3 the lower ends of the

guides

21 and 31 will preferably be provided with packing rings 14D such as illustrated in Fig. l for making sealed engagement, in Fig. 2 with the exterior surfaces of the mold sections 20 and the castings formed between adjacent sections, and in Fig. 3 with the external surface of the cast strips 37 or like cast parts.

With further reference to Figs. 3 and 4, while the 4 ribs 36 are shown as being part of the guide member 31 to define cavities 37 for casting strips, it will be apparent to those skilled in the art that such ribs may be provided by longitudinally grooving the exterior surface of the rod-like member 30 while having a regular rectangular opening through the guide member.

In summary, it is now apparent that with the apparatuses disclosed herein it is possible to economically produce sound castings with great rapidity and in conformance with the mold cavities by reason of evacuation of the mold cavities to facilitate iowing of the molten metal thereinto, such evacuation withdrawing air and gases which otherwise might be trapped in the mold cavities. While the apparatus illustrated show

special passages

13, 24, and 32 in the guide means 10, 21, and 31, respectively, for communicating the cavity with the

vacuum chambers

6, 23, and 34, it can be seen that by maintaining the pool of molten metal under vacuum, the gases in the mold cavities and in the molten metal pool will bubble through the molten material to permit deoxidation and flow of the molten material thereinto by gravity. Moreover, because the molding material is caused to flow into the receptacle 1 and into the vacuum chamber 6 (or 23, or 34 as the case may be) as a thin layer, the same is more effectively degassed and deoxidized.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

l. Apparatus for casting articles comprising a mold having a cavity, a guide through which said mold is adapted to be moved, said guide providing an inlet and an outlet for the introduction of said mold thereinto and for discharge of said mold therefrom, a receptacle for molten material, a chamber, means for controlling the atmosphere in said chamber, said chamber and receptacle each surrounding said guide between such inlet and outlet thereof, said guide being formed with passages communicating such chamber and the molten material in said receptacle with the mold cavity in said mold as the latter is moved through said guide whereby the atmosphere in such cavity is first removed and the cavity is then illed with molten material from said receptacle, and means for solidifying the material thus filling such cavity after the latter passes the passage which communicates with the molten material in said receptacle and prior to discharge of said mold from the outlet of said guide.

2. The apparatus according to claim l characterized further in that adjacent mold blocks are adapted to be inserted into said guide at one end of the latter and to be moved therethrough to communicate the respective cavities therein with the passages in said guide.

3. The apparatus according to claim l characterized further in that the mold cavity is defined between said mold and guide whereby the cavity is evacuated and illed with molten material during the course of its movement through said guide.

4. The apparatus according to claim 2 characterized further in that the mold blocks preceding and following such passages have sealed, sliding engagement with said guide.

5. The apparatus according to claim l characterized further in that said mold comprises an elongated rodlike member forming a longitudinally extending passageway with said guide into which the molten material ows during movement of said member through said guide.

6. Apparatus for casting articles comprising a mold having a cavity, an inert atmosphere chamber containing a receptacle for molten metal with respect to which said mold is adapted to be moved to successively expose the cavity therein to such atmosphere and to communicate the cavity with molten metal in said receptacle for iilling said cavity, an upwardly extending guide connected to the upper part of said chamber which embraces said mold and provides a seal against inflow of atmosphere into such chamber as said mold moves through said guide into said chamber, said receptacle being provided with a downwardly extending guide connected to the lower part of said receptacle and aligned with said upwardly extending guide for guiding movement of said mold downwardly and for forming with said mold and metal therein a closure for said receptacle as said mold is thus moved, and means for cooling said mold progressively upwardly from the bottom thereof and thus correspondingly solidifying the metal therein and providing a shrinkhead of molten metal which compensates for shrinking of the metal below.

References Cited in the tile of this patent UNITED STATES PATENTS Grey Sept. 14, Grey Nov. 14, Moxham Apr. 29, Davenport Sept. 11, Sherwood et al. Dec. 18, Sherwood Apr. 23, Sendzimir Mar. 23, McCarroll et al. Sept. 7, Thompson Dec. 20, Galloway Aug. 6, Smithson et al. Jan. 12,

Claims

6. APPARATUS FOR CASTING ARTICLES COMPRISING A MOLD HAVING A CAVITY, AN INERT ATMOSPHERE CHAMBER CONTAINING A RECEPTACLE FOR MOLTEN METAL WITH RESPECT TO WHICH SAID MOLD IS ADAPTED TO BE MOVED TO SUCESSIVELY EXPOSE THE CAVITY THEREIN TO SUCH ATMOSPHERE AND TO COMMUNICATE THE CAVITY WITH MOLTEN METAL IN SAID RECEPTACLE FOR FILLING SAID CAVITY, AN UPWARDLY EXTENDING GUIDE CONNECTED TO THE UPPER PART OF SAID CHAMBER WHICH EMBRACES SAID MOLD AND PRIVIDES A SEAL AGAINST INFLOW OF ATMOSPHERE INTO SUCH CHAMBER AS SAID MOLD MOVES THROUGH SAID GUIDE INTO SAID CHAMBER, SAID RECEPTACLE BEING PROVIDED WITH A DOWNWARDLY EXTENDING GUIDE CONNECTED TO THE LOWER PART OF SAID RECEPTACLE AND ALIGNED WITH SAID UPWARDLY EXTENDING GUIDE FOR GUIDING MOVEMENT OF SAID MOLD DOWNWARDLY AND FOR FORMING WITH SAID MOLD AND METAL THEREIN A CLOSURE FOR SAID RECEPTACLE AS SAID MOLD IS THUS MOVED, AND MEANS FOR COOLING SAID MOLD PROGRESSIVELY UPWARDLY FROM THE BOTTOM THEREOF AND THUS CORRESPONDINGLY SOLIDIFYING THE METAL THEREIN AND PROVIDING A SHRINKHEAD OF MOLTEN METAL WHICH COMPENSATES FOR SHRINKING OF THE METAL BELOW.