US3826303A - Apparatus for casting molten metal/foaming agent composition - Google Patents

Abstract

A novel vessel and an improved method of casting batch liquid materials which solidify on cooling or standing utilizing one or more upright open-ended body elements with mixing means therein initially seated on the bottom of a mold; the method is especially advantageous for casting foamed metals.

Description

United States Patent [191 Jarema et al.

[ APPARATUS FOR CASTING MOLTEN METAL/FOAMING AGENT COMPOSITION lnventors: Chester P. Jarema, Detroit; Leonard M. Niebylski, Birmingham, both of Mich.

[73] Assignee: Ethyl Corporation, Richmond, Va.

[22] Filed: Apr. 24, 1972 [21] Appl. No.: 247,040

Related US. Application Data [63] Continuation-in-part of Ser. No. 50,139, June 26,

1970, abandoned.

[51] Int. Cl B22d 41/00 [58] Field of Search 164/136, 335; 75/20 F, 75/222; 264/41; 425/256, 447, 817

[56] References Cited UNITED STATES PATENTS 2,533,986 12/1950 Atterbury ..425/447X [11] 3,826,303 [451 July 30, 1974 4/1961 Willemsen 425/412 2/1967 Bjorksten 164/79 X FOREIGN PATENTS O R APPLICATIONS 8,284 4/1913 Great Britain .[164/136 322,169 6/1920 Germany 164/136 Primary ExaminerRobert D. Baldwin Attorney, Agent, or FirrriDona1d L. Johnson; Robert A. Linn ABSTRACT 2 Claims, 9 Drawing Figures t u ji m I 3 I S r s 4 g- 2/ Pmmmma 3.826.303

SHEET 10? 3 FlGURE 2 FIGURE 3 Fl U RE 4 INVENTOR.

CHESTER P. JAR-EMA LEONARD M.N|EBYLSKI PAIENTEUJUUOIHH SHEEI 3 OF 3- FIGURE IA APPARATUS FOR CASTING MOLTEN METAL/FOAMING AGENT COMPOSITION CROSS REFERENCE TO RELATED APPLICATION This application is a Continuation-in-Part of copending application Ser.' No. 50,139, filed June 26, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention is directed to an improved apparatus for batch casting liquid materials especially foamed metals, utilizing a novel vessel.

Casting, that is, transferring a liquid material to a mold where it will subsequently solidify is ordinarily accomplished by pouring the liquid material out of the vessel containing the liquid material directly into a mold. Simple examples are pouring a gelatin dessert into a mold, pouring water into an icecube tray for freezing, and the like. Where transfer time is an important element in casting, e.g. polyurethane foams, liquid elastomers, liquid resins, e.g. epoxy resins and polyester resin, metal foams and the like, pouring the liquid material from its container into a mold can create problems such as poor mold filling, undesirable air entrapment, loss of material due to set up in the container and the like. The problem with casting foamed metals, such as foamed aluminum, is particularly perplexing because of the relatively short time interval between adding a foaming agent to the molten metal and foam formation. One expedient which has been utilized successfully in overcoming some of the aforesaid problems is the use of a continuous method of preparing and casting the liquid material. This continuous preparing/casting system has been applied to foamed metal casting as illustrated in the following U. S. Pat. Nos.: 2,937,938, 2,974,034, 2,983,597, 3,005,700, and 3,214,265.1-Iowever, this expedient is not applicable to batch operat1ons..

It has been discovered that in batch operations, a very rapid transfer of castable liquid material from the holding and/or preparing container into the mold can be achieved by using a novel vessel in which the mold bottom serves as the bottom of the mixing vessel. Thus, especially when transfer time is important for example, with foamed metals, the transfer of liquid to the mold can be directly and efficiently accomplished with essentially no time lag by simply separating the mixing vessel from the mold when the liquid material is ready to be cast. In this way, the liquid material quietly, smoothly and rapidly flows directly into the mold, avoiding problems associated with pouring.

SUMMARY OF THE INVENTION An improved'vessel for casting and/or preparing casting liquid materials comprises (a) one or more main body elements open at opposite ends which provide cavity for holding said liquid, and (b) a bottom element which seals the lower aforementioned open end and is also the bottom of a mold into which the material is to be cast. A feature of the vessel is that the bottom element and main body elements are completely vertically separable An improved'method of casting liquid materials especially foamed metals utilizes said vessel.'

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 isa section view through a vessel of the present invention. FIG. 1A is a section view through the vessel of the present invention showing a stirring means 8.

FIG. 2 is a section through the vessel of FIG. 1. It shows the body element 1 separated from the bottom element 4 permitting the liquid material 2 to flow into the bottom element 4.

FIG. 3 is a section through a vessel of the. present invention having two body elements, 1 and 1.

FIG. 4 is 'a section through the vessel of the present invention. It illustrates a hemispherical body element la.

FIG. 5 is a side view section of a substantially hemispherical main body element having a lower opening lb of different shape.

FIG. 5A is a top view section of FIG. 5 at A-A', showing the shape of the lower opening 1b.

FIG. 5B is a partial section top view of FIG. 5 section at'BB and the bottom element 4. It shows the pattern of the liquid material2 flowing out of the main body element 1 into the bottom element 4.

FIG. 6 is a partial section view of a vessel of the present invention. It includes an illustration of a sectioned heating element 7 which surrounds the main body element 1. A platform 5 driven by a piston 6 holds the bottom element 4 in a sealing position against the main body element 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of this invention is a novel vessel for casting and/or preparing a castable liquid material. The vessel comprises (1) at least one main body element open at opposite ends in which the liquid material to be cast is held and (2) a bottom element which seals the lower of said open ends. The bottom element is also the bottom of a mold into which the liquid material is to be cast. When the liquid material is ready to be cast, the bottom element and main body elements are vertically separated. The liquid material thus immediately and directly flows into the mold(which is the bottom element). As compared to any standard techniqueof'casting which requires a pouring operation, the present method utilizing the novel vessel substantially reduces the time lag between ready to cast" and cast; and since there is no actual pouring from one container into another, splashing and problems caused thereby are also virtually eliminated.

The method of casting liquid materials utilizing the vessel of the present invention is also an embodiment of this invention.

Referring to the drawings, FIG. 1' illustrates in cross section a vessel of the present invention. The main body element 1 is open at both ends. It provides a cavity in which the liquid material 2 to be cast is held. The lower end of the main body element 1 is provided with a suitable gasket 3 against which the bottom element 4 is seated, thus sealing the main body element 1 and holding the liquid material 2 therein. FIG. 1A shows a stirring means 8 within body element 1. FIG. 2 shows the vessel of FIG. 1 shortly after the two elements 1 and 4 are separated and the liquid material 2 flows directly into the mold or bottom element 4. FIG. 3 illustrates a vessel in which two main body elements 1 and l are utilized. The number of main body elements may be varied as the particular total system requires. FIG. 4 illustrates a vessel of the present invention in which the main body element 1 is hemispherical in shape. FIG. 5 shows a hemispherical main body element 1a with a lower opening 1b of different shape than the main body element 1. FIG. 5A shows that said opening lb is substantially rectangular. FIG. 5B shows a top view of FIG. 5 at section B-B' in which the bottom element 4 or mold has the same shape (rectangular) as the lower opening of main body element 1. The desirability of the main body element 1, or at least the lower opening of said body element, and the bottom element or mold having substantially the same shape improves the liquid flow pattern by making it better coincide with the mold shape. FIG. 6 shows an assembly which includes a heating element in section 7 which surrounds the main body element 1 and a platform 5 driven by a movable piston 6 which serves as the means for holding the bottom ele ment 4 in a sealing position against the main body element 1; and which also permits lowering of the bottom element 4 from the main body element 1 when the liquid material held in the main body element It is ready to be cast. i

Although the method and apparatus of the present invention can be used with any castable material which is ordinarily liquid or can be liquitied as for example by heating, the present method is of especial value when batch casting liquid materials in which time from ready to-cast to cast is of importance. Our method is especially of value with batch casting a liquid mate rial which subsequently foams in the mold, especially when the liquid material is molten metal. By batch casting is meant preparation of a certain volume of liquid material which is then used to fill a discrete mold or molds. This is in contrast to continuous casting where the liquid materials are being mixed and fed continuously either to a discrete mold or to a moving mold for example,a shaped conveyor belt.

The present vessel may be constructed of any materials which are suitable for handling the particular liquid material which is to be cast. In other words, if the liquid material were corrosive, then a material of construction which wouldnot be attacked by the liquid material should beused; and if a considerable amount of heat is required to liquify and prepare the material (e.g., metal) for casting, the materialof construction should be sufficiently heat resistant. Thus, the properties and characteristics of the liquid. material to be cast will help determine the type of construction material required for the present vessel.

Although the bottom element may seat directly against the lower open end 'of the main body elements, a gasket is more conveniently provided at the lower end to facilitate sealing. This is illustrated in FIGS. 1-4 and 6. This gasket material should be a material which will withstand the conditions which are required for casting and/or preparing liquid materials. The gasket should bottom element or, mold'which comprises the present vessel can-also be varied as required. Ordinarily, where the main body element of the present vessel is also utilized to prepare the liquid casting material and agitation and mixing of the ingredients is required, then main body element shape which would facilitate such mixing would best be used. With regard to the volumes of the main body elements and the mold or bottom element of the present vessel, there is no fixed relationship although ordinarily the volume provided by the main body elements should be adequate to hold sufficient liquid material to fill the mold or bottom element to the desired level. The size of the lower open end of the main body elements should also be adequate to permit the flow of liquid material into the mold to be accomplished in the time required for the system.

Although the shape of the main body element and the bottom element or mold of the present vessel are not directly interrelated, it is preferred that at least the lower open end of the main body element and the mold or bottom element be of similar shape (see FIG. SB for example). By maintaining such a shape relationship, the flow patternof the liquid material during the casting step is such as to effect a more uniform'flow of liquid from the main body element into the mold or bottom element. Thus, for example, if a square mold served as the bottom element of a vessel of the present invention and the material to be cast required maximum mixing and agitationthen a hemispherical main body element having a square opening at its lower end (see FIG. 5A for example) would provide a most efficient flow pattern for casting the liquid material. If desired of course, the shape of the entire body element may be uniform with said open end. It is also contemof any mold by the use of a detachable lower end openlowing aluminum alloys are examples of useful alloys for preparing suchfoam: ALUMINUM ASSOCIATION DESIGNATION A 7075 (l.6lo Cu, 2.5/o Mg, 0.3/o Cr, 5.6/o Zn, re-

mainder A1) 2024 (4.5/0 Cu,-

A1) 5086 (0.45/o Mn, 4 .0/o Mg, 0.l/o Cr, remainde A1) 6063 (0.4/o Si, 0.7/o Mg, remainder Al) Almag 35 (6 8/0 Mg in Al) 1,000 series A1 (9-9.6/o minimum Al) 201 l (5.5/o Cu, 0.S/o Pb, 0.5/o Bi (remainder Al) 7 /0 Mg, remainder 2218 (4.0/o Cu, 1.5/o mg, 2/o ni, remainder A1) 3005 (l.2/o Mg, 0.4/o Mg, remainder A1) 4042 (12.2/o Si, 0.9/o Cu, l.1/o Mg, 0.9/o Ni,

- remainder Al) 4043 (5lo Si, lo A1) 8280 (l.5/o Si, 1.0/o Cu, 0.5/o Ni, remainder Al) Magnalium 70/o Al, 30/o Mg In general, preparation of foamed metals involve blowing the molten metal with a suitable gas generating (cellulating or foaming) agent such as magnesium hydride, titanium hydride, zirconium hydride and the like. Air properly entrained in a molten metal may also be used in preparing metal foam. Where a blowing agent such as a metal hydride, preferably zirconium hydride, is used, a viscosity controlling additive may be added to the molten metal during the preparation of the foam to help control the foam density and pore uniformity. The viscosity controlling agent is generally added before the foaming agent (or air) is introduced into the molten metal. Representative examples of foam compositions and methods of preparing the molten mixtures are found in the patents cited above.

To illustrate the advantages of the present vessel and method in casting foamed aluminum, a batch of molten aluminum alloy containing zirconium hydride blowing agent and CO as a viscosity control additive was prepared in a heated mix pot with adequate agitation. The mix pot was provided with a bottom which could be opened to permit the molten aluminum mixture to pour into a mold placed beneath the pot. When the molten aluminum mixture was ready for casting the bottom of the pot was opened, and the molten aluminum mixture poured into a mold held beneath the mix pot. The cast aluminum mixture in the mold was then cooled externally by means of air blowers. The resultant molded aluminum foam was examined and found to have imperfections caused by splashing and splattering in the center of the mold where the molten metal poured from the mixing pot. This splashing and splattering also caused envelopment of air which resulted in further defects in the foam.

Substantially the same composition of molten aluminum alloy containing zirconium hydride and CO was then prepared in a vessel of the present invention. The mixture was prepared in substantially the same way using the same agitation system and mixing cycle. The foam was then cast into a mold, as per the present method, by lowering the mold (or bottom element) from the main body element until all the molten aluminum mixture had flowed into the mold. Transfer of the molten metal from the main body element was quiet, rapid and essentially complete (compared to the mixed pot method) before the foaming occurred. Thus, the foam was generated in the mold and substantially filled the mold. The cast aluminum foam was then cooled by means of air blowers. Examination of the cast aluminum foam showed it to be substantially free from any of the splashing and splattering defects and consequent air envelopment defects using the aforesaid mixing pot. Furthermore, the foam prepared using the present method was more uniform throughout than the foam produced using the aforesaid mixing pot method.

It is readily apparent then that the present vessel and method of casting liquids and especially molten metals and foams such as aluminum foams, provides a means for substantially improving batch casting in liquids. In addition to the readily evident substantial improvement in quality of the final cast product, the present vessel and method offer the following additional advantages compared with conventional mix pot/pour systems:

1 The system is simple in operation.

2 The vessel has no moving parts and consequently dimensional tolerances are not critical.

3 Transfer of liquid material from main body element to bottom element or mold is rapid, direct and quiet flow is insured.

4 Loss of casting liquid caused by residual liquid being retained in the main body cavity after casting is substantially reduced; and in the case of foamed metals such as aluminum, this also effects more accurate control of the foam density.

The present invention has been disclosed above- It encompasses two embodiments: (l) a novel vessel, and

b is open at opposite upper and lower ends,

2 means, located within said main body elements, for

mixing said molten tion, and 3 a relatively large container-shaped bottom element (a) which is seated against and closes the lower open ends of said main body elements during said mixing and (b) which is also the bottom of a mold into which said composition is to be cast, said main body elements and said bottom element supported by means whereby said bottom element is completely and independently vertically separable from said main body elements for quiet, rapidand essentially complete transfer of said composition to said mold.

2. The vessel of claim 1 wherein said lower open ends are provided with suitable gasket means against which said bottom element is seated.

metal/foaming agent composi- $223? UNITED STATES PATENT O E- QERTIFICATE OF CORRECTION Patent No. 3, 826,305 v Dated July 30, 197

Inventor) Chester ,P, Jarema et a1 It is eertified'that error-appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Page 1, under the heading "ABSTRACT, last line, after .1

"metals add the phrase wherein the mold is independently lowered from the body elements for quiet, rapid and essentially complete transfer of the molten metal/foaming agent composition to the mold Column 4, line 61, aluminum alloy example 2218, "2 ni" should be 2"/ Ni Signed and sealed this 5th day of November 1974.

(SEAL) Attest:

MeCOY M. GIBSON JR. C. MARSHnLL DANN Attestimg Officer Commissioner of Patents

Claims (2)

1. An improved vessel for preparing and casting molten metal/foaming agent composition which consists essentially of 1 one or more cylindrical upright main body elements, each of which a defines a cavity for holding said composition, and b is open at opposite upper and lower ends, 2 means, located within said main body elements, for mixing said molten metal/foaming agent composition, and 3 a relatively large container-shaped bottom element (a) which is seated against and closes the lower open ends of said main body elements during said mixing and (b) which is also the bottom of a mold into which said composition is to be cast, said main body elements and said bottom element supported by means whereby said bottom element is completely and independently vertically separable from said main body elements for quiet, rapid and essentially complete transfer of said composition to said mold.

2. The vessel of claim 1 wherein said lower open ends are provided with suitable gasket means against which said bottom element is seated.

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