US2842820A - Apparatus for casting metal - Google Patents

Description

July 15, 1958 J. B. BRENNAN 2,842,320

APPARATUS FOR CASTING METAL Filed Jan. 12, 1955 4 sheets-sheet 1 July 15, 195.8 J. B. BRENNANy A 2,842,820

APPARATUS FOR CASTING METAL Filed Jari. 12, 1955 y 4 sheets-sheet 2 INVENTOR.

July 15, -1958 J. B. BRENNAN APPARATUS FOR CASTING METAL Filed Jan. 12, 1955 Fig. 11 Flag. 12 Fig. 15

4 Sheets-Sheet 3 INVENTOR.

, 4 Sheets-Sheet 4 July 15, 1958 J. B. BRENNAN APPARATUS FOR CASTING METAL Filed Jan. 12, 1955 2,842,820 APPARATUS Fon CASTING METAL Joseph B. Brennan, Cleveland, Ohio Application January 12, 1955, Serial No.`481,456

3 Claims. (Cl. 22-75) This invention pertains toY a method of casting and laminating metal and constitutes a continuation-in-part of my application Serial No. 202,707, tiled December 26, 1950, now abandonded. According to this invention, molds in guided sequence are passed through a pool of molten metal, the molds being heated thereby and being filled with molten metal while immersed therein. After being lled with molten metal in, for example, a crucible with a pool of molten metal therein and by passing through said pool of molten metal, the molds in one example are passed through an externally embracing closetting cooling die pereferably located underneath the crucible containing the molten metal.. The molds may 'be conventional except that they have preferably a top and bottom gate and their sides are uniform in size.

According to one Iform of this invention, the molds have uniform exterior surfaces, and a uniform exterior cross-section, so that they will contact intimately and closely a passageway or guide through a molten metal pool and also through a cooling die. In the practice of this form of my invention, the mold preferably is made with an orifice leading through the exterior Wall thereof, or with a series of orifices, or with openings defined by parting lines, or with top and bottom parting orifices where `one mold abuts that one following and preceding it in passing through a pool of molten metal.

According to another form of this invention, the cavity of the mold is located on the exterior surfaces thereof, the Vcavity being formed as a depression in the exterior surface of the mold. in the practice of this second form of my invention, an exterior portion only of the mold need have a uniform cross-section, this characteristic being used to control the gauge of the finished casting and to aid in guiding the passage of the mold through a die for solidiiication of the metal in the mold.

According to'still another form of my invention, there is no `exterior or interior cavity, the mold being in the form of a solid mandrel, having a uniform exterior surface and uniform cross-section.

The molds may lbe made preferably of an investment such as zirconium oxide or molding plaster. Among other Well known materials, core sand, molding sand binders, and carbon also may be used to make the molds. The cavities of the molds are preferably made by the use of volatile, meltable, or combustible models as is customary in the so-called lost wax process. Y

The molds are preferably heated or baked, and the model thereby removed prior to passage through the pool of molten metal. However, it is to `'be understood that rthe molds may be heated and baked and the model removed during the time of passage through the pool `of molten metal, the model thereby being removed by the action of the heat of the molten metal itself.

This invention can be applied to making metal castings l United States Patent 147,466, filed February 18, 1950, now Patent No.

2,714,235, granted August 2, 1955. This invention also may be used for many kinds of precision casting.

Other objects and advtanges of the present invention will become apparent 'by the following description of preferred methods of practicing the art of my invention.

Referring to the drawings herewith:

Fig. 1 is perspective view of a model used in carrying` out the process of my invention in one of its forms;

Fig. 2 is a transverse sectional View of the model illustrated in Fig. l; Y

Fig. 3 is a sectional view of a mold with model included therein, for use according to my invention;

Fig. 4 is similar to Fig. 3 except that, in this instance, the model shown and disclosed in Fig. 3 has been removed;

Fig. 5 is a transverse sectional view of the mold after the mold has been passed through a pool of molten metal;

Fig. 6 is a transverse sectional view of a model and metallic article to be laminated included therewith;

Fig. 7 is a sectional view of a mold with metal to be laminated and the model, as shown in Fig. 6, included therein, for use according -to my invention;

Fig. 8 is a view similar to Fig. 7, except that in this instance the model has been removed therefrom;

Fig. 9 is a transverse sectional view of the mold, metal to be laminated, and laminated layer included therein;

Fig. 10 is a transverse sectional view of molten metal Crucible and apparatus suitable for practicing the preferred as described in application Serial No. 598,080,led June forms of my invention;

Fig. 1l is a transverse sectional view of another type for practicing the method of laminating a metal article in accordance with the teachings of my invention;

Fig. 13 is a transverse sectional View of a continuous mold similar to those shown in Figs. ll and 12;

Fig. 14 is a transverse sectional view of a mold suitable to the manufacture of continuous tubing or pipev according to my invention;

Fig. 15 is a cross-sectional view taken on the line 15--15 of Fig. 14; and

Fig. 16 represents a sectional view of molten metal c rucible and variable pressure apparatus suitable for practrcmg my invention.

Further referring to the drawings, Figs. 1 and 2 show a model generally indicated at 1, consisting, for example, of a die casting of conventional low melting point die cast metal, or wax, or easily combusted plastic, or other Y material such as is commonly used to make models for use in the so-called lost wax method of casting.

The model is accurately dimensioned in accordance with the dimension of the article desired to be produced. The only differences between the dimension of the model and that of the desired finished article are those resulting because of the shrinkage of the meta-l from which the iinal product is cast. By the use of my invention, this shrinkage is reduced to a low value because of the fact that additional molten metal is being fed into the mold while the metal therein is shrinking.

In addition to this peculiar advantage of my invention, the usual and well known procedure for determining the degree of shrinkage in the desired cast product is 4followed in determining the dimension of the die cast model 1.

The die cast model 1 is provided with a projection 2 extended therefrom at an appropriate point for the reais freed from any burrs or other imperfections as, for example, the ridge or line left by the parting line of the die casting mold, or of other molds, used to produce such model. As illustrated in Fig. 3, the model 1 then is embedded in the investment 3, the investment 3 being of a heat-resisting oxide suchas zirconium oxide Acompacted and having binders therein in accordance to well known practice. Any suitable investment material may be employed which, when molded about the model 1 and dried and baked and pressurized, will retain its shape in a substantially rigid and coherent manner with the projectionZ of the model extending through the investment 3 to the outer surface of the so-formed investment.

Fig. 3 illustrates the model encased in the investment 3, a groove or grooves 16 extending from the projection or extension 2 to the outer edge of the investment 3 to provide passageway for the ingress of molten metal. The projection 2 extends through the -gate 16 to the outer surface of the s o-formed investment. It is preferable also that an opening or a plurality of openings extend from the bottom of the investment 3 to the lower portion of the model 1.

Alternatively in place of the groove 16, extending from the projection or extension 2 to the outer edge of the investment 3, and opening 15, at the bottom of the investment 3 and extending to the lower portion of the model 1, it is possible to make the model 1 in such a manner that the model has extensions which correspond to the openings or grooves 15 and 16 and which project through the 4bottom surface of the investment 3 as shown, and which also extend to the exterior of the outer periphery of the investment 3 in Fig. 3 as shown, thus to replace and ll and define the grooves 15 and 16 when the model is removed.

After the model 1 has thus been embedded in the investment, as illustrated in Fig. 3, the latter is heated to a temperature sufficient to melt the material from which the model is made or sufiicient to ignite the model so that it can be burned out. Fig. 4 illustrates a mold which previously had included therein a model which now has been removed, as is common practice in precision casting. The melted model, if of meltable material, is then drained out of the investment through openings 15 and 16, leaving therein a cavity 4, Fig. 4, there being a passage 5 which extends from the cavity 4 to the outer surface of the mold at the point formerly occupied by the projection 2 lof Fig. 3. Also an opening 15 extends from the cavity 4 to the bottom surface of the mold as explained above.

After the mold has been thus prepared as illustrated in Fig. 4, the investment 3 with the cavity 4 therein is ready for use as is later to `be explained.

My invention is also especially adapted to the production of composite metallic articles as, for example, a sleeve bearing having an outer reinforcing and supporting part :of steel and an inner layer of cast bearing metal adhering to and supported by the steel body.

In carrying out this modification of my invention, the pattern generally indicated at 8 in Fig. 6 will consist of the component 9 which is also the component of the desired finished yarticle and the lamination 10 of meltable or burnable material. The model generally indicated at 8 is provided by incorporating the component 9 with a die casting 10 which is formed of low melting point die cast metal or wax or plastic material, with projection 11 extending therefrom, projections corresponding to `the openings or grooves 15 and 16, Fig. 7, also extending therefrom if desired.

The model i@ and the component 9 as illustrated in Fig. 6 are embedded in an investment mold 12, Fig. 7, formed in the manner previously indicated, after which the mold is heated sufficiently to melt away or to burn away the die casting 10 and thus to permit draining or removal from the mold of the metal, plastic, or wax die casting 10 leaving a cavity generally indicated at 13 in 4 l Fig. 8 having openings 15 and 16, Fig. 8, extending therefrom, the projection 11 of Fig. 7 representing the appropriate portion of the opening 16 of Fig. 8.

Again for purposes of illustration, the gatings 15 and 16 shown and disclosed in Figs. 7, 8 yand 9 are not shown in the model disclosed in Fig. 6, it being possible to make the model with a gating corresponding to the openings f. 15 prior or subsequent to the enclosure in the investment Instead of the investments 3 or 12 shown in the drawing, it is possible according to this invention to use multiple-piece permanent molds, as of metal or graphite or aluminum oxide, which are pre-formed and which can be parted after the casting has been made therein, it being possible to use these molds over and over again.

In carrying out my invention, a series of exteriorly similar investment molds 3 are stacked, as is shown in Fig. l0, in alignment over and inside of the penforate guide tu'be 17 as of graphite, 'which guide tube -has openings 17a through and about its cylindrical wall, and which guide tube 17 is surrounded by the molten meta-l pool 22 in the curcible 21, heat being supplied thereto by the high frequency coils 19.

I apply pressure to the topmost mold 3 and thereby force the stacked molds through the sleeve 17 and the close-fitting die 20 and 'through the aligned cooling ldie 18, so that the metal, by passing through the groove 16 intjo t-he molds 3, forms the casting 24 therein as the molds are forced down through the molten metal 22. After lthe castings 24 are made, they are passed along and chilled by the cooling die 20 with the cooling coils 18 therein and ejected at the lbottom of the cooling die 18 als solid metal l6.

The casting 24 then is had by removing thereafter the investment Stherefrom. It may be noted that, iu the example illustrated 'by Fig. 10, the investment molds 3 do not have the openings 15 extending from the bottom Vof the cavity Z3 to the exterior surface of the investment 3. Where the openings 15 are employed, they `are substantially in alignment with the opening 7 or 14 of the next preceding investment mold 3.

Where molds similar to those `described in Figs. 1 to 9 inclusive are employed in the practice of my invention, Figs. 5 and 9 represent the finished product wherein the molten metal of the pool has filled the cavity of the mold to form the finished product. In Fig. 5, the finished casting 6 has gatings 15a, 16a and 5a corresponding to the openings 15, `16 and 5 of Fig. 4. yIn Fig. 6, the component metal `9 and the laminated layer 10 constitute the finished pattern. In this latter instance, the laminated layer has gatings corresponding to the openings 15 and 1-6 of lFig. 8,.

Figs. l'l, l2, 13 and 14 illustrate various other modifications of molds or shapes suitable to the Ipractice of my invention. In Fig. l=1, the investment Imold generally indicated at 25 has a sleeve 28 extending therefrom, the

sleeve 28 fitting into the hollow portion 27 of the next preceding mold 25. The portion 26 of the mold 25 has a uniform exterior surface and a uniform cross-section.

The molds 25 are passed continuously and successively fitted together lthrough a guide tube into a pool of molten metal and through a cooling die in a manner similar to that previously described with reference to Fig. l0, the metallic isleeve 30 Ithus being cast around and about the recessed portion 29 of the sleeve 28.

The uniform exterior cross-section and uniform surface at the portion 26 in the mold 25 acts as a guide and alignment agent in the passage of `the mold 25 through the guide tube and through the cooling die. The gauge or the vdimension of the metallic rbushing or sleeve 30 is determined by the distance between the surface 29 of the mold 25 and the exterior of the surface 26.

-In the practice of the modification, the mold 25 again may Vconsist of any refractory material such as graphite or the like, or it may consist of a destructi'ble investment 1J material, the material suitable for use in the investment 3 'and 12 being satisfactory to the construction lof the mold 25. `Preferably in the modiation illustrated in Fig. 11, `a destructible material is not used, and the individual units may be used over and over again.

In Fig. 12, many of the parts are identical to those in Fig. Y1l and are described 'by like numbers. In Fig. `12,a component metallic sleeve or bushing 31 is iirst placed around the surface 29 of the mold 25. The molds are then passed in sequence through a guide tube into a pool of molten metal and through the cooling die in a manner similar to that described in reference to Fig. l1. However, in this instance, the finished cast product 33 consists of the component metallic sleeve 3.1 and the laminated layer 32 thereoverand bonded thereto.

The 'gauge or Athe dimension of the lamination 32 in this instance is determined 'by the 'distance between the -exterior surface'of the componen-t metal 31 and the extension of the surface 26.

In Fig. 13, I have lshown a continuous Idestructible investment mold material wherein the mold indicate-d at 34 rthas the external projections indicated at 3S and wherein *the metal is cast about vthe surface 36 of the mold 34 to -"iorm the iinished ring casting 30. Here again, the dimension of` the finished product can be controlled in `a manner similar to that previously described with reference 'to' Fig. 1l. In the practice of the modification of my invention shown in Fig. 13, a destructible mold material `is desirable in order that theiinis-hed casting 30 may be `removed from the mold.

In Figs. 14 and l5, I have illustrated a mandrel 37 about which is cast the tubing 3S. In thepractice of the modification shown in Figs. 14'and l5, accurate Asplines are employed in the guide tube in Vorder to control thethickness `of the tubing 33 and the alignment of the "mandrel `.37. In other respects, the method of passing Vmust :be located in the` guide t-ube above the. point where *the metal tube 3*@ so'lidiiies.

Where it is desired to cast strips of metal about 4the mandrel in preference., toV atubtin'gythesplines lare extended intoA the cooling zone in ac- `cordancewith the width of the strips which it isdesired to secure, the `widths of the strips being dened by the distances between the splines.

'In order to aid in the withdrawal of the strips through "the udie, `.a clearance may Vbe allowed between the splines :and the mandrel to an extent that a thin iin is cast between 'the strips. The existence of these tins enables theY casting to hug the mandrel and thus'l-essen the amount of pulling and the tension means which maybe required to draw the strips from the die. The mandrel 37,may be made of any suitable mold material in accordance lwith the principles herein previously explained.

The metal in and around a given section off the mold =or forrnpreferably shouldbe liquid prior to 'the lentry ,of .that section` of each mold or form linto the solidication Zone in orderrthat `shrinkage and solidication is Thus, prefmetal continues to be fed into the connected cavity of the -moldat this point so that the -moldcavity is substantially full when it passes out of the -solidication zone and a casting completely iillingthe mold cavity is` obtained, which is desirable. mold cavities are not continuous and connected, the metal Of course,-in those cases where` the will not continuevto -feedafter the mold opening has entered the solidification Zone.

I have described casting-previously in my Yapplication Serial No. 147,466, led February 18, 1950. Insofar as common subject matter is involved, this application constitutes a continuation in part of this prior application.

According to this invention, itis also contemplated ,to apply pressure such'asgaspressure ,tothe molten metal pool when itis being applied .to ,the mold. This Acan be done by kenclosing the apparatus of Fig. l0, allrexcept the outlet portion thereof, in a Apressure crucible device such asis described in myPatent No. 2,371,604.

If desired, the mold with the models therein Amay ,be made by continuous extrusion methods, cured by Ahigh frequency heat with thermo-resins, as bindersand without interruption passed through thepool of molten metal, the cavities being `lled`thereby- Or, if chosen, `divided multiple-piece moldsmay be used so longas they will suit the conditions. For example,.a two-piece mold may be made and used according to conventional Vplaster or ceramic or permanent mold practice which will preferably conform Where necessary tothe `cooling die inside ,sur- 'face and dimensions.

By my invention, metal of constant or varying crosssection may beproduced continuously if amodel, as` an .extrusion of plastic or wax or combustible material, is

provided .which may be surrounded with ceramic mold material and then have themodel evaporated or burnt out or otherwise removed, whereafter the metal fills in the cavity as the so-provided moldis passed through the pool of molten metal. It is possibleV to usedivisible molds of metal or ceramicmaterial such VasV graphitewhich may be stacked and/ or fastened together in aligned relation and which may be re-used after emptying of their castings.

It is possible by my, inventionto make castings as .accurate as any obtainable bythe so-called centrifugal lostwax methodor by more crudemethods, also to do so continuously and save much labor and energy and material thereby.

It is also possible to make laminated metals-in strip form or in individual piece form by my invention. The

.hase metal as Well as the investment containing same becomes heated by my invention so -that a.good bond is obtained. Thus, steel and copper, or steel or silver can be well bonded.

To make a strip of laminated steel and bronze, the

Ymodelshould be a ribbon, for example, of steel faced with a layer of combustible or volatile or meltable material, such as tin and/or lead or plastic model material which, when invested and cured and run through the .pool of molten metal, will be heated and faced thereby `molten strip metal due to the fact that the investment mold is so hot as to'equal the temperature of the metal being cast.

It is of considerable value in some cases to have the cavities 23 in stacked molds 3 aligned and interconnected 'on top of each other so that there is a movement of metal downward toward the chill zone in addition to the normal ow toll the cavities because of degassing caused by. progressive and constant chill as in a string casting.

Fig. 16 illustrates a variable pressure chamber'generally indicated at 39 in which is enclosed the Crucible 40 containing molten metal 41 therein. lGas pressure-is supplied to the variable pressure chamber 39 through the gas inlet tube 42. Alternatively, the inlet pipe 42 may serve as an outlet pipe, andthe air of the atmosphere or other gaseous impurities may be removed and a vacuum created in the variable pressure chamber 39.

If desired, an inert gas may then be supplied to the chamber 39, where it is desired to cast under a pressure other than that of a vacuum. In this manner, oxygen-free metal may be Cast with the apparatus of my invention. The gas pressure gauge 43 accurately registers the amount of pressure in the chamber 39, and the pressure in the variable pressure `chamber 39 can be regulated in accordance with the pressure desired by the use of a shut-olf valve (not shown) in combination with the gas inlet pipe 42.

The metal 41 in the crucible 40 is maintained molten by means of the electro-Conductive coils 44 connected to the externaly circuits 45 and 46 and are maintained in pressure-sealed relationship with the variable pressure vessel 39 by means ofthe conduits 47 and 48.

The mandrel or mold 49 is moved through the packing gland seal 50located`in the detachable top plate 51 of the variable pressurecrucible 39, and into the molten metal 41 by way of the guide tube 52 having therein the perforations 53.` The molten metal flows through the perforations 53 inthe guide tube S2 and around the mandrel or mold `49. As the mandrel or mold 49 moves downward throughthe die 55, which is cooled by a cooling uid flowing through the coils 56, a soliditication of the molten metal 41 is effected and the solid casting 54 thereby is obtained. A

The detachabletop plate 51 is secured to the lower portion 56 of `the variable pressure chamber 39 ,by means of the bolts 57.` Thus, when the supply of molten metal in the Crucible 40 is to be replenished, the top plate 51 may be removed from the lower portion 56, thereby permitting access to the interior of the pressure chamber 39. i

The mechanism of Fig. 16 may be varied in accordance with various of the modifications previously explained with reference to Figs.` 1 to 15. For example, the splines 57 of Fig. 16 are employed much in the manner previously set forth. Again, by way of illustration, the apparatus of Fig. 16 .may be used Vin conjunction with a mold having a cavity on the interior thereof, in a manner similar to that described in reference to Figs. 11, A12, and 13. Or the mold may have therein a depression cavity, as is again shown in Figs. 11, 12, and 13.

Further, rather than the mandrel or mold 49, the mold 3 of Fig. 4, or the mold 25 of Figs. 1l and 12, or the mold 34 of Fig. 13 may be substituted in place thereof. Still other modifications herein disclosed may be employed in the apparatus of Fig. 16, it also being possible for example, to secure a laminated casting by the practice of the method therein disclosed.

If desired, the constancy of the pressure may also be aided by maintaining a constant head of metal 41 in the Crucible 40 by the use of a feed Crucible located externally or internally of the pressure Chamber 39.

Impurities, such as oxides, Can be reduced and converted into pure metal by bubbling a deoxidizing gas, such as carbon-monoxide, through pipes 58.

Upon release of gas into pipes 58, the shut-off ball valve 59 is released upward by the pressure of the v gas to permit the. ow thereof into the Crucible 40 and l through the molten metal, the ball valve S9 being retained in. its upward position by the guard 60. The ball valve 59, in this illustration, is of a weight greater than that of the molten metal which it displaces. When, in this example, the gas owing into pipe 58 is shut off, the ball valve 59. closes the pipe outlet and thus prevents a backward ow of molten metal into pipe 58.

The use of a vacuum is also possible in the practice of my invention. For example, the inlet pipe 42 may be used to create a vacuum in the variable pressure chamber 39, thus to remove gaseous impurities from the molten metal or to eliminate the presence of free oxygen in the pressure chamber. After the creation of a vacuum in the variable pressure chamber 39, the pipe 42 may be employed to admit an inert gas into the Chamber, thereby to create a desired pressure for casting purposes.

Although I have described my invention in terms of metal casting, it is to be understood that the principles of the invention may be applied and the objects thereof may be achieved in the Casting of ceramic materials, quartz, mica, germanium, silicon, glass, and other fusible materials, as well asin the Casting of metal.

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.

l therefore particularly point out and distinctly Claim as my invention:

l. A casting apparatus comprising a downwardly extending tubular mold guide, an adjoining downwardly extending cooling die below and aligned with said guide, a mold of substantially the same cross-section size and shape as said guide and die adapted-to be moved downwardly through said guide for filling with molten material and through said die for cooling of said mold and solidification of the material. therein, and a molten material supply crucible around said guide, said guide being formed with an opening through which molten material flows from said Crucible into said mold when the latter is disposed Within said guide, said mold when thus disposed within said guide and when moved downwardly through said Cooling die constituting a Closure for said crucible.

2. The apparatus'of'claim 1 wherein a series of superimposed molds of such cross-section size and shape are successively moved downwardly through said guide and said cooling die for lling with molten material and for solidication of the material therein.

3. A Casting apparatus comprising a downwardly extending mold guide, an adjoining downwardly extending cooling die below and aligned with said guide, a mold guided by said guide and die for movement downwardly through said guide for' tilling with molten material and through said die for Cooling of said mold and solidication of the material therein, and a molten material supply Crucible laterally adjacent said guide, said guide being yformed with an opening through which molten material flows from said Crucible into said mold when the latter is disposed in-said guide, said mold and said cooling die being of substantially the same cross-section size and shape whereby said mold and solidified metal when moved downwardly through said Cooling die constitutes a Closure for said crucible.

References Cited in the tile of this patent UNITED STATES PATENTS 365,902 Boulton July 5, 1887 418,154 Bayles Dec. 31, 1889 1,342,127 Mallen June 1, 1920 1,789,979 Jones et al Jan. 27, 1931 1,822,256 Watt Sept. 8, 1931 1,879,336 Foley et al. Sept. 27, 1932 1,972,945 Nilson Sept. 11, 1934 1,984,385 Sherwood et al Dec. 18, 1934 1,999,114 ySherwood Apr. 23, 1935 2,092,284 McCarroll et al Sept. 7, 1937 2,214,235 Ragan Sept. 10, 1940 2,225,373 Goss Dec.- 17, 1940 2,371,604 Brennan Mar. 20, 1945 2,543,936 Reynolds Mar. 6,1951 2,569,150 Brennan Sept. 25, 1951 2,716,790

Brennan Sept. 6, 1955

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