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March 13, 1962 J. B. GERO 3,024,507 METHOD OF VACUUM CASTING Filed July 30, 1959 ' 2 Sheets-Sheet 1 l» e \ I | I I I l r l l l 22 FIG. 2 / '/ as g3“ \ I, \ /_\ I 4+ / INVENTOR v I //BY J?‘ [gr/(75w - ATTORNEY March 13, 1962 J. B. GERO 3,024,507' METHOD OF VACUUM CASTING Filed July-30, 1959 2 Sheets-Sheet 2 /0/n i ' INVENTOR a.‘ 23/01” . BY . M- ATTORNEY I" United States "atent O 3,024,501 Patented Mar.- 13, 1962 2 1 from each ladle or heat, a series of vacuum chambers are necessary further complicating the problem. It is an object of the invention to improve methods John B. Gero, Magnolia, Mass, assignor to Gero Metal and apparatus for vacuum casting and to devise means lurgicai Corporation, Boston, Mass, a corporation of 5 for more effectively and quickly establishing and main Delaware taining a vacuum in order to produce quality steels with Filed July 30, 1959, Ser. No. 830,983 desirable magna?ux and micro-cleanliness ratings and 3,024,507 METHQD 6F VACUUM CASTING 5 Claims. (Cl. 22-209) better physical properties to permit production vacuum pouring of multiple large or small ingots from one heat This invention relates to methods and apparatus for vacuum casting of molten metals and, especially, to vacu 10 or ladle; and to make possible the development of new and unique alloys as a result of the removal of inclusion um casting of heavy forging ingots and the mass produc forming materials. tion of rolling ingots wherein gaseous components of Another object of the invention is to devise a new harmful nature are in part removed from the molten combination of sealing compound and casting apparatus metal during the period that the molten metal is being for vacuum casting whereby unusual sealing effects may be accomplished and also whereby the evacuation of air poured into an ingot mold or ladle. The invention, in one preferred form is directed espe cially to treatment of molten steel in that state which to produce a vacuum may be carried out in a highly con is commonly referred to as “unskilled.” This term is employed to distinguish a molten steel in which certain venient manner. contrasted with a molten steel in which gases have been materials may be introduced into a body of molten metal as it is being poured under vacuum to the end that there may be induced reactions tending to further reduce th Still another object of the invention is to provide a gases are present in a relatively uncombined state as 20 method of vacuum casting in which chemically reactive caused to combine with a material such as aluminum to provide a so-called “killed” metal. It should be under stood that the invention is not, however, limited to this 25 or any other particular application. occurrence of harmful gases. ‘ ' A further object of the invention is to devise a method operation is a more recent development of vacuum cast of vacuum casting in which the percentages of reactive alloying elements used in forming desired alloys of steel ing and is employed primarily for the removal of hydro may be modi?ed or controlled while a vacuum is in effect ber necessarily comprises a heavy housing structure usual after disclosed presents several unique techniques for dealing with the problems outlined and accomplishing the foregoing objectives with respect to various types of Degassing of large forging ingots during the pouring to provide desirable results. gen from killed steels in order to diminish the suscepti Another object is to control the degree of vacuum bility of a steel to form internal hair-line ?ssures com~ 30 exerted as well as to modify vacuum conditions by furn monly referred to as ?akes during cooling cycles to room ishing an atmosphere of predetermined chemical nature temperature from the hot working temperature. which may be conducted through a region of pourin Degassing is conventionally carried out at the present and then evacuated. ' time by utilizing a special vacuum chamber in which is The method and apparatus of the invention herein mounted an ingot mold or a ladle. This vacuum cham 35 ly made up of a top section and one or more lower sec tions which can be secured together in sealed relation ship in order to make these sections airtight. For seal ing purposes, having regard for the high temperature vacuum casting. These techniques are, in‘ preferred em 40 bodiments of the ‘invention, based on the concept of conditions which exist in pouring molten metal, it is creating a vacuum by evacuating gases through a side~ After a vacuum has been created in the housing struc ture, hot metal is transported to a pony ladle located on molten metal on any conventional sealing means which the top of the chamber housing. As the hot metal is poured into the pony ladle, the heat of the metal will, thermal shock and expansion of the mold. wall portion of a molten metal containing pouring box customary to employ heavy rubber sealing rings. These from which molten metal is to be poured, and supporting rings are located in suitable sealing ?ange portions which such a box in airtight relationship for a limited period extend around outer peripheral surfaces of the sections in protectively spaced relationship to hot metal passing 45 directly on an ingot mold. Thus, it becomes possible to eliminate a separate vacuum chamber which has here into the ingot mold during a pouring operation, Water tofore conventionally enclosed the ingot mold and several cooling may be employed in some cases. other novel techniques are‘rendered feasible. In a conventional structure of this class, the top sec In this connection, it will be appreciated that an im tion of the vacuum chamber is provided with a pouring aperture which is normally closed by a fusible diaphragm. 50 mediate obstacle to holding a box and mold member in sealed relation is the high temperature effect of the is capable of producing an airtight joint including the I have discovered that a high vacuum seal may be after a short interval, melt the diaphragm and the molten 55 produced and maintained for a short interval by a new metal falls into the chamber. The vacuum within the technique which may be conveniently referred to as chamber operates to disperse the metal into molten drop “Transient Thermal Sealing.” This technique may, I lets and to remove gases such as hydrogen and limited ?nd, be accomplished by the use of special sealing means amounts of oxygen and nitrogen. It.is found that establishing a satisfactory vacuum 60 including a novel sealing compound which has the ability to temporarily resist ?owing or decomposing from rela with such a form of vacuum casting apparatus is a costly and careful manipulation to maintain a satisfactorily high tively intense heat conducted through the metal body portions of the pouring box and mold during the time in an operative position for the production of large forg ing ingots or small rolling ingots and readily disengaged matter comprising a mixture of three essential com and complex procedure requiring expensive equipment interval which corresponds to the short period in which vacuum. The vacuum must be capable of being held in the presence of very high temperatures, either for short 65 molten metal is passing from the pouring box to the ingot mold. or long periods, and the equipment should be of such As an example of one sealing means which is suitable construction that it may be simply and quickly spaced when not in use. Existing equipment does not meet for this purpose, I may employ a new composition of ponents—(I) a low molecular weight glycidyl polyether, these requirements. It is also pointed out that, if it (II) a condensation product of a low molecular weight becomes necessary to vacuum pour more than one ingot glycidyl polyether and ethylene glycol and ('III) a curing 3,024,507 3 4 agent composed of pyromellitic dianhydride mixed with more apparent from the following description of preferred the anhydride of a dicarboxylic acid. When these com ponents are combined in the hereinafter described pro portions a resinous mixture is obtained which upon ex posure to heat at elevated temperatures resists melting and cures to a solidi?ed adherent elastic body. In addition to the above ingredients it may be desirable to include var ious ?llers and a cure accelerating agent. The composition of matter noted above is intended to embodiments of the method and apparatus as shown in the accompanying drawings, in which: FIG. 1 is a side elevational view illustrating diagram matically casting apparatus as employed in the inven tion; FIG. 2 is a detail plan view; FIG. 3 is a vertical cross-sectional view of the vacuum casting apparatus of the invention as it appears when re be representative of sealing compound means which is 10 ceiving molten metal; and FIG. 4 is a detail cross sectional view of a modi?ed sufficiently ?uid to “wet” and adhere to metal surfaces of sealing arrangement. casting members; which is characterized by the ability to Referring more in detail to these ?gures, numeral 2 cure when brought into contact with metal surfaces heated to temperatures of from 250~500° F. to form a tough elastic adhesive; and which in this cured state is capable of resisting ?owing or melting in the presence of much greater temperatures, i.e. 500—l000° F. for a limited denotes an ingot mold 2 of the invention having an ingot cavity 4 which tapers downwardly, as shown in FIG. 1. This mold member is preferably seated on a heavy ?at bottom stool 6. At its upper side, the ingot mold is formed with a flat seating surface 8 which extends around the ingot cavity period of time corresponding approximately to an ingot pouring interval. In combining the sealing compound described with a 20 4 to provide a support for a removable pouring box mem ber, generally indicated by the arrow 10. molten metal containing box in airtight relationship with In accordance with the invention, I have devised as an ingot mold, in accordance with the invention, there component parts of this pouring box 10 an upper metal is, in effect, produced an exceedingly high vacuum sealed containing section 10a and a lower conduits section 10b. conduit through which molten metal may be conducted from the basket to the ingot mold. 25 These box sections are separated by a transverse wall 100 through the center of which is formed a pouring aperture By the expression “exceedingly high vacuum,” I refer 12 which is normally closed by a fusible closure cap 14 to micron guage readings of an outer magnitude of as low as four (4) microns at the point where the vacuum of aluminum or other suitable material. The cap 14 is secured by bolts as ‘16 and 18. In the presence of hot pumping means “blanks off.” This micron reading is in contrast to optimum micron readings possible with con 30 metal discharged from a transporting ladle 22, shown at the upper side of FIG. 1, the closure member 14 becomes ventional equipment of from 300-500 microns. fused and will then allow the hot metal to ?ow through I further ?nd that I may exert this exceedingly high the aperture 12 and then through the conduit section 10b vacuum at the conduit region in close proximity to the to ?nally be received in the mold cavity 4. stream of molten metal which is poured from the basket The lower conduit section 1% also receives an an and also in close proximity to the metal collecting in the 35 nular refractory “hot top” 19 which is necessary on all ingot mold to produce unexpected results of great sig~ killed steels. The refractory 19 must be thoroughly ni?cance. The high vacuum, when thus exerted, not only heated and dried before placing on the vacuum mold. Of disrupts and disperses the molten stream of metal in the form of a spray of ?ne particles, but also causes this importance to the success of the invention is the seal 20 metal, as it collects in the mold, to be vigorously agitated between the hot top and mold. The best seal to prevent the ?ow of steel between the mold and hot top is tamped steel wool. Wet refractory cements give off water and gas which makes trouble. Back pouring is the practice and to ebullate in a particular manner wherein portions of collected material continuously rise up around the inner surfaces of the ingot mold and fall over into the for open atmosphere pouring. central portions of the mass. I further construct the box 10 with means for evacuat' I have further discovered that, by exerting a vacuum in ing gases through the conduit section 10b, as indicated in the manner described, I am enabled to greatly increase FIG. 1. The evacuating means includes a passageway the removal of harmful gases and to modify the per formed through the sidewall portion of the conduit sec‘ centage of alloying additive which may be retained in the steel. It is believed that the combined effect of removing tion, as shown, and into which is tightly ?tted a tubular gases as the stream is dispersed in the conduit region and 50 member 26. Attached at some convenient point to the outer end of the tubular member 26 is a vacuum pump also removing gases which are thrown up by the con unit 29 of some conventional nature. tinuous ebullience produced is the reason for this im proved vacuumizing, although this is stated by way of When the box 10 is arranged in the seated position opinion only. shown in FIG. 1 and the vacuum pump 29 is started, air will be evacuated from the conduit section and the ingot I have further discovered that I may introduce reacting cavity and a vacuum will be created when the high vac materials directly into the conduit region Where the uum type seal of the invention is exerted between the molten metal leaves the box and where some degassing pouring box and the mold. The effectiveness of my seal takes place. I ?nd that by bringing reactive materials in is indicated by the degree of vacuum attained. Normally a suitable dispersed state into the conduit region and simultaneously dispersing the molten metal into minute 60 I ?nd an absolute pressure of forty microns is reached droplets in the presence of these dispersed reactive mate in about two minutes, and twenty microns in about four minutes. Pressures below ten microns are consistently rials, there may be carried out desirable chemical reac tions in both the dispersed and collected material which reached in ten minutes. The lowest pressure developed reactions bene?cially use up small quantities of harmful has been four microns. Speed of pump down is extremely gases. Resultant reaction products are rapidly carried off 65 critical in pouring a series of molds. Time delays cause through the vacuum equipment. I may also introduce temperature losses in the molten metal and solidi?cation alloying additives into the stream of molten metal as it or skulls in the ladle or box. Another important feature of the invention is the is poured under vacuum, either during or after the use of method of so-called transient thermal sealing in which reactive materials. A further novel feature of this step of adding a mate 70 the sealing compound earlier noted is applied at the junc rial at the particular period indicated consists in the fact that substantially all of an alloying additive may be thus tion of the relatively hot seating surface 8 of mold 2. As utilized in the invention the sealing compound is em introduced and caused to serve its intended alloying pur ployed in a substantially ?uid condition so that it may poses without undesirable side reactions taking place. be applied to the metal surfaces of the box and mold and These and other novel features and objects will be 75 will wet and adhere to these surfaces and penetrate 3,024,507 O the pouring box resting on the mold surface 8 and, in the value of “n” decreasing as the quantity of epichloro hydrin is increased. Considering for purposes of illustration the most widely ordinary working conditions, the mold and box under usual foundry conditions will be at temperatures of from employed dihydric phenol, bis (4-hydroxy phenyl) di methyl methane (hereinafter termed Bisphenol A) the 200° F. to 500° F. dinlycidyl ether has the formula: slightly into the pores of the metal surfaces. It will be understood that the sealing compound is applied with In FIG. 1, I have indicated the sealing body applied in one desirable form on the mold and box and denoted by the numeral 30. As is further shown in FIG. 3, the sealing compound occurs as an irregular mass of mate 10 rial which ?lls in around the outer line of junction of the mold and box in such a position that, while it effectively seals this region, it is, nevertheless, protected by the thick where n of Formula 1 is zero. By employing a mole ratio of epichlorohydrin to Bisphenol A of 10:1 the di glycidyl ether is produced in a fairly pure state. As the the mold itself. mole ratio is decreased the proportion of higher molecular I have also discovered that the use of a sealing com weight polyethers increases. In general, mole ratios of pound such, for example, as that indicated by the com 2:1 to 10:1 give average molecular weights of about pound 30, may be very desirably carried out by utilizing 350 to 450. In practice it is found that though the size specially formed surfaces at the portion of the mold which supports the pouring box. For example, as illus 20 of the major portion of the polyether molecules may be controlled, some small proportion of longer and shorter trated in FIG. 4, I may form a mold body 2a with a length molecules will be present. In addition side reac recessed portion 21), constituting in effect an annular tions may occur with some formation of intermediates, groove extending all the way around the mold body 2a. but the quantity of these side products does not notice This groove is of a radial width substantially exceeding ably in?uence the properties of the resin. the thickness of a pouring box section 10g. In this groove In preparing the sealing compound 30 I produce com I locate a body of sealing compound 30a, which com ponent I, the low molecular weight glycidyl ether by pletely ?lls the groove so that the pouring box section using as a dihydric phenol, bis (4-hydroxy phenyl) di~ 10g is embedded in the sealing compound and substantial methyl methane, having an average molecular weight of portions of the body of sealing compound are present at from 350 to 450. With other dihydric phenols this both the inner surface 10f and the outer surface 10k. A range will vary slightly. Referring to Formula 1 the second heat resistant sealing body is employed at the base average molecule of the ether will contain between 1 of the mold, as indicated by reference character 10m in and 1.5 R's (aromatic radicals) and “n” will vary from FIG. 3, and between the mold body and the ?at bottom 0 to. l. The epoxide equivalent (weight of resin in grams stool 6. containing 1 gram equivalent of epoxy) should be be The purpose of this arrangement is to deal with and tween about 175 and 225. Assuming the resin chains compensate for, the abrupt thermal expansion and con to be substantially linear with an epoxy group terminat traction of the mold and box which takes place during ing each end, then the epoxide equivalent is One-half the the pouring of the molten metal. The sudden change in average molecular weight. The viscosity of the poly temperature may, I ?nd, produce a rapid stress amounting ness of the box wall section as well as the thickness of to a thermal shock which, in some cases, operates to 40 ether will vary from 5,000 to 20,000 c.p.s. as measured break down and render useless sealing means which have been tried in earlier efforts in the art to hold a seal. In the arrangement of a seat of the invention, the compound being of a compressible somewhat elastic nature, is com with a Brook?eld LVT-SX viscometer with No. 5 spindle at 6 rpm. at 25° C. Many commercially available epoxy resins with suitable properties may be used. Among these are “Bakelite ERL-2774” and “Bakelite preserve a sealing effect on one side of the box even Co., Div. of Devoe & Reynolds Co.; “Epon” is the trade pressed at one side of the other of the box 10g with the 45 ERL-3794,” “Epi-Rez 510,” “Epon 820” and “Epon 828.” “Bakelite” is the trademark of Union Carbide compound being squeezed between this member and an Corp; “Epi-Rez” is the trademark of the Jones-Dabney adjacent groove surface of the mold. This operates to ' though the seal is broken on the other side when the ex 50 mark of the Shell Chemical Corp. Component II is the reaction product of component I pansion occurs. In thus combining both an inner and with a glycol, for example, ethylene glycol. The ratio of outer sealing means with the inner and outer surfaces of epoxy to hydroxy can be varied from l/0.5 to 1/2 with the pouring box, a desirable cooperative effect is present little effect on the ?nished compound. The reaction may by utilizing the refractory material 19 and the steel wool backing 20 to shield the sealing compound to a limited but desirable extent. The sealing compound 30 is of the class of compounds containing in general polyepoxide materials. Epoxy be carried out by mixing the desired quantities of epoxy and ethylene glycol and heating to 150° to 185° C. for 1 hour or until the mixture becomes homogeneous. The product has a molecular weight of 385 to 485 and is believed to consist primarily of the product resulting resins are prepared by the reaction of a dihydric phenol and epichlorohydrin in the presence of sufficient alkali 60 from the reaction of one epoxide ring with an hydroxyl group of the glycol. Since component I can be consid to maintain the reaction mixture substantially neutral. ered to contain an average of two epoxy groups per The predominant constituent of the reaction product is represented by the formula: molecule, it is quite certain that the primary condensation (1) 0 O OH wherein R represents a divalent aromatic hydrocarbon radical and “n” is an integer. By varying the ratio .of epichlorohydrin to the dihydric phenol, compositions of varying molecular weight (varying “n”) may be obtained, product resulting from such controlled conditions may be represented by the formula: 8 For convenience I shall refer to the condensation prod uct as the 50% condensate of component I with a glycol. Component II lends ?exibility to my resin composition, but must be used in controlled amounts. I have found empirically that the ratio of component I to component II may vary from 20 E E 1'. o as nent I and ethylene glycol in the previously described ratios. It has the following properties: Viscosity ______________________ _. Speci?c gravity _________________ _. Color ________________________ __ Epoxide equivalent _____________ _. 550 cps. at 25°C. 1.14. 2 (Gardner Scale). 385. Hydrolyzable Cl _______________ _. 0.15%. Twelve parts of component I was blended with 88 parts with good results. When the quantity of component II 10 of component II and 43 parts of phthalic anhydride and passed through a colloid mill to reduce the particle size is more than 88 parts, the resin after curing is gel-like of the phthalic anhydride to 0.025 mm. or less. Care and weak. When the amount of component II is less must be maintained to keep the temperature below about than 80 parts, the composition cures to a brittle, easily 50° C. during passage through the mill. After cooling to cracked material. The third component (III) of my composition is a 15 room temperature 2.5 parts of pyromellitic dianhydride was added together with 55 parts of micronized silica, 35 curing agent which acts to cross-link the epoxy com parts of atomized aluminum, and 350 parts of short ?ber pounds. The curing agent which I prefer to use is a mix asbestos. The mixture was thoroughly blended while ture of a primary curing agent, pyromellitic dianhydride, maintaining the temperature of the mix below about 25° and a secondary curing agent selected from the group of organic acid anhydrides. The anhydride mixture is used 20 C. and 0.3 part of pyridine were added to the mixture to act as a cure accelerator. The composition was applied in stoichiometric quantities based on the amount of epoxy to two steel rods about 2.5 cm. by 1.25 cm. by 30 cm. and hydroxyl groups present in the resin mixture. A and the steel rods were pressed together end to end. slight excess, about 5%, is employed in the case of solid These rods were heated to 205° C. for 15 minutes to cure acid anhydrides to allow for uneven dispersion of the an hydride powders in the resin. 25 the composition. The rods were then raised to 315° C., allowed to cool to room temperature and heated again Anhydrides of dicarboxylic acids are well known in the to 345° C. The resin bond remained strong with no art as curing agents and include phtalic anhydride, maleic cracks or thermal decomposition noticeable. anhydride, succinic anhydride, dodecenylsuccinic anhy As a further test of the ability of the composition of dride, and hexahydrophthalic anhydride. Depending upon the particular anhydride curing agent 30 Example I to withstand high temperatures, a sample of the composition which had been cured at 205° C. for used, the proportions of primary and secondary curing 15 minutes was placed in contact with a surface at 315° agents in component III may be varied within certain well C. for a period of eight hours. There was no evidence of de?ned limits. I have found that 2 to 15 parts of pyro serious charring or decomposition, and the sample re mellitic dianhydride and 42 to 17 parts of secondary an hydride for every 100 parts of resin give satisfactory seal 35 tained its normal compressibility. ing materials for high temperature uses. The manner in which component III is added to the Example II Component I was prepared in the manner described in epoxy compositions will depend upon the particular an US. Patent No. 2,682,515, column 6 under the heading hydrides in component III. Phthalic anhydride must ordinarily be passed with the resin through a colloidal 40 “Polyether A.” Component H was prepared by adding 46.5 grams of mill to get a good dispersion. Maleic anhydride, on the ethylene glycol to 180 grams of component I. The re other hand, is sut?ciently ?ne to be mixed in by hand. action mixture was maintained at 150° C. for 1 hour. When it is desired to shorten the curing time, various Upon cooling there resulted a clear, low viscosity mono well-known cure accelerators may be added to the com position. Among these are alphamethylbenzyl dimethyl 45 functional-epoxy ?exibilizer. amine, n-butyl amine, pyridine and N-methyl pyridine. These are used in catalytic amounts, from 0.5 to 3% of the weight of the resins in the composition. Sixteen parts of component I was mixed with 84 parts of component II and blended well at 25° C. To the mix was added 13.8 parts of pyromellitic dianhydride, 19.4 parts of maleic anhydride, 75 parts of micronized silica, In addition to the above basic ingredients it is advan tageous to add various ?llers to the composition to add 50 25 parts of atomized iron, and 150 parts of short ?ber asbestos. After mixing well a homogeneous blend of body, adjust viscosity, increase thermal conductivity and milk-like consistency was produced. To this was added hence achieve more even cure and lower the coe?icient 0.4 part of N-methyl pyridine to act as a cure accelerator. of the thermal expansion. Among the ?llers which can The composition was spread on steel rods and baked be used are atomized aluminum, iron, copper, aluminum oxide, silica powder, mica, and asbestos. Fibrous ma 55 for 20 minutes at 175° C. After carrying out the heat ing and cooling steps of Example I, the ‘bond was found terials such as ?ne asbestos tend to bind the resin to to retain its strength. gether and counteract differences in thermal expansion Though in the foregoing examples component II was between the resin and the bonded metal. The quantity in each case a condensate of component I and ethylene of ?ller may be varied from a few percent to three or four times the weight of the resin. The compounding 60 glycol, this need not be the case. Component II of Exam ple I could have been substituted for component II of manipulations are well-known to those skilled in the art. Example II and vice versa. It is only necessary that The following examples illustrate the preparation of component II be approximately a 50% condensate of a the compositions of my invention. glycol and a glycidyl polyether epoxy resin having a mo Example I 65 lecular weight between about 350 and 450, an epoxide A commercial epoxy resin, “Epi-Rez 510" with the fol lowing properties was employed as component I: Viscosity ______________________ _. 12,000 cps. at 25° C Speci?c gravity ________________ __ 1.15. Color ________________________ __ 3 (Gardner Scale). Epoxide equivalent _____________ __ 185. equivalent of 175-225, between 1 and 1.5 aromatic radi cals per polyether chain and a viscosity between 5,000 and 20,000 cps. ‘Also, though I have shown component I to be made 70 from Bisphenol A and epichlorohydrin for purposes of illustration, other dihydric phenols are suitable. These include resorcinol; 1, l-bis (4-hydroxphenyl) ethane; 1, l-bis (4-hydroxyphenyl) propane; l, 1~bis (4-hydroxy phenyl) butane; 2, 2-bis (4-hydroxyphenyl) butane and l, Component II is also a commercial epoxy resin, “Epi Rez 507” which is the condensation product of compo 75 l-bis (4-hydroxyphenyl) 2-methyl propane. Hydrolyzable Cl _______________ __ 0.1%. ‘3,024,507 9 10 In operation, the mold and basket are assembled as shown and air is evacuated from the mold cavity and con duce alloying additions into the molten metal as it passes through the conduit section into the ingot mold. As shown in FIG. 2, I may provide for this purpose a second tubular member 36 having a feed inlet suitably closed when not in use and through which additives may be passed. This tubular member is connected into the con duit section to provide a suitable vacuum. This vacuum is maintained in effect and hot metal M of the unkilled class referred to above is poured into the metal containing section 10a from the ladle 22. The heat of this molten duit section wall and may also include at its outer end a metal melts the closure member 14 and the molten metal viewing piece 39. This viewing piece 39 enables an op starts to ?ow through the passageway 12. As the hot erator to observe conditions at the point where the metal metal enters the degassing chamber 20, it is instantly sub jected to disruptive forces produced by the vacuum de 10 is subjected to vacuum and dispersed and also permits a limited view of portions of the mold cavity. scribed and the stream of entering metal is separated It is pointed out that, by means of this arrangement, into a multiplicity of small metal droplets. reactive materials which produce oxides or sulphides may In this dispersed droplet state, gases such as hydrogen, have their reaction products removed by vacuum. By in~ nitrogen and oxygen, in the form of carbon monoxide, are drawn off by the vacuum forces. At the same time, 15 troducing material in the manner noted, there is an op portunity for the additives to combine with materials in the molten metal, as it collects in the ingot mold, is caused the molten metal producing objectionable gases which are to continuously ebbulate and, in the course of this agita carried off in the vacuum stream. One chemically reac~ tion, a further additional and important removal of tive material which I may add consists of “misch-metal” gases takes place and especially there may be removed small quantities of carbon monoxide. The percent of 20 which acts to combine with sulphur in deoxidizing metal. Other materials which may be added for the purpose of gases in the metal may, I ?nd, be desirably reduced in alloying include titanium, vanadium, chromium and the both of these ways, i.e., from the dispersed material and like. It will be observed that, in thus introducing an the collected material, and a highly signi?cant reduction alloying additive such as noted, there is found an op in carbon content may occur when the initial carbon con tent is low. This removal of carbon monoxide serves 25 portunity to ?rst remove undesirable substances present both as a deoxidation treatment for high carbon steels in the molten metal as it is poured and then the alloy and as a decarburization treatment and deoxidation treat ment for very low carbon content steels. ing additive may be dropped into the mass at a time when it can be most effectively employed. From the above disclosure, it will be evident that I have discovered a new and desirable method of degassing In accordance with a further important feature of the invention, I provide for further removal of gases for a which may also be carried out in conjunction with adding short period after the actual pouring operation has termi nated. I accomplish this novel step by introducing into reactive materials as well as alloying additives. By means of these procedures, it is possible to produce better alloys the basket 10 special closure means for sealing the pour ing aperture 12 from the upper side thereof at a point just of known type, as well as some new alloys. before the last portion of molten metal leaves the basket 35 so that the vacuum is either maintained or renewed and a It is pointed out that, by means of this vacuum sealing means described, it becomes possible to carry a highly simpli?ed and efficient vacuum casting operation with saving in cost of handling, time consumed and equipment used. The two principal components are readily assem type now exceedingly difficult to produce by conventional 40 bled and just as readily separated from one another when secondary degassing takes place. I ?nd that, by means of this secondary or extended vacuumizing, I may produce a very low carbon steel of a desired. It is pointed out that, with the vacuum effect furnace practice. For example, I may provide for a car bon content as low as .05 and lower, as will be evident exerted through the basket, there is eliminated the need from an inspection of the following table. of a special housing to form a vacuum chamber and, yet, a high efficiency may be realized. Vacuum Material Convention- Casting by al Casting thetlnven ion While I have disclosed preferred embodiments of the invention, it will be understood that various modi?ca tions may be practiced within the scope of the appended claims. This application is a continuation, in part, of my co pending application, Serial No. 656,228, ?led May 1, 1957 now abandoned. Unkilled 10% 0. Steel __________________ __ Having thus described my invention, what I claim is: 1. In a method of vacuum casting the steps which Unkilled 20% 0. Steel __________________ __ I . C Killed 12% Cr. Steel ____________________ __ 066% Nz_-__ 13% 0. 039% N2 .()l2% AL." 01% Al 30% C .... __ % C. Killed Cr-Ni-Mo Steel __________________ _- 027% N2____ 027% N2. 042% Al. ___ .037% Al. include positioning an uncured plastic ?owable sealing material between the surface of a cast iron casting mold and the surface of a vacuum chamber having an upper sealable opening supported on the mold, subjecting the sealing material to heat conducted through the casting mold to provide a cured solid, elastic vacuum tight seal 60 ing mass extending around the line of junction of the casting mold and chamber conforming to the surfaces thereof, sealing said vacuum chamber and evacuating air from the chamber to provide a high vacuum, ?owing molten metal through said upper sealable opening and through the evacuated chamber into the casting mold while simultaneously maintaining the sealing mass in seal ing relationship between said surfaces for a period at accomplished. This usually requires about twenty min least as long as the ?owing interval, and subjecting said utes after all of the metal has passed into the mold. This sealing mass to heat of increasing intensity which is also allows su?icient time for the solution of any alloy additions. At this point, the heat ?ow reaches an inten 70 transmitted from the molten metal through the casting mold to said sealing mass, said sealing relationship of sity causing the compound to decompose and become said mass between said surfaces thereafter being destroyed. charred or volatilized. The period during which a required amount of metal suitable for ?lling the ingot mold will flow is of limited duration. In this short time interval, the heat which ?ows toward the sealing compound 30 does not reach a maxi mum intensity until the desired vacuumizing has been In addition to removal of gases by connecting a vacu 2. A method as claimed in claim 1, wherein said mold is provided with a continuous well extending around to realize other advantages. For example, I may intro 75 said line of junction for receiving said surface of said um member into the conduit section, I am also enabled 3,024,507 11 12 vacuum chamber, with said sealing material being posi tioned in said well against said surfaces. References Cited in the ?le of this patent UNITED STATES PATENTS 3. A method according to claim 1 in which the heat resistant sealing mass includes a low molecular weight glycidyl polyether, a condensation product of a low mo 5 lecular weight glycidyl polyether and ethylene glycol and a curing agent. 4. A method according to claim 1 in which the heat resistant sealing mass includes a low molecular weight glycidyl polyether, a condensation product of a low mo 10 lecular weight glycidyl polyether and ethylene glycol and a curing agent composed of pyrometllitic dianhydride mixed with the anhydride of a dicarboxylic acid selected from the group consisting of phthalic anhydride, maleic anhydride, succinic anhydride, dodecenylsuccinic anhy drided, and hexahydrophthalic anhydride. 5. A method ‘according to claim 1 wherein the de struction of said sealing relationship is caused by thermal decomposition of said sealing mass. 2,140,607 Thompson ____________ __ Dec. 20, 1938 2,187,594 2,197,259 2,734,241 2,851,375 2,885,751 Wean ________________ __ Jan. 16, 1940 Nead ________________ __ Apr. 16, 1940 Samuel ______________ __ Sept. 9, 1958 Hornak ______________ .. May 12, 1959 339,721 866,231 Great Britain _________ __ Dec. 18, 1930 Germany _____________ __ Feb. 9, 1953 797,973 Great Britain __________ __ July 9, 1958 Southern ____________ __ Feb. 14, 1956 FOREIGN PATENTS OTHER REFERENCES Epoxy Resins their Application and Technology by Henry Lee Kriss Nelville (1057), pages 260~270 relied upon.