US2787817A - Automatic feed casting apparatus - Google Patents

Description

April 9, 1957 J. B. BRENNAN AUTOMATIC FEED CASTING APPARATUS Filed Oct. 24, 1951 INVENTOR. JOSEPH B. BEEN/VAN A77'OBNEX5.

AUTOMATIC FEED CASTING APPARATUS Joseph B. Brennan, Cleveland, Ohio Application October 24, 1951, Serial No. 252,938

1 Claim. (Cl. 22-73) The present invention relates generally as indicated to an automatic feed casting apparatus in which, between the loading, for example, of empty molds for casting or of pressed compacts of powdered metal to be sintered into the apparatus, and the unloading of the filled molds or of the sintered articles from the apparatus, the entire process is carried out under vacuum to insure certain improved results in the castings or in the sintered articles thus produced in the apparatus.

This invention has for one of its main objects the provision of an apparatus of the character indicated which makes possible the aforesaid desired ends in an economical, simple, and efiicient manner for rapid production of accurate metal castings and sintered powdered metal articles.

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 claim, the following description and the annexed drawing setting forth in detail one illustrative embodiment of the invention, this being indicative, however, of but one of the various Ways in which the principle of the invention may be employed.

In said annexed drawing the single figure is a central vertical cross-section view of a preferred form of the apparatus constituting the present invention.

Referring now to the drawing and first to the construction thereof as used in casting, the same comprises a crucible 1 and surrounding high frequency heating coil 2 or the equivalent to which crucible molten metal is adapted to be supplied as through the tube 3 which leads from one or more feed crucibles 4, said tube 3 and crucible 4 also having high frequency heating coils 5 and 6 or the like therearound to maintain the molten metal at desired temperature. The control of the supply of molten metal to the feed crucible 4 is effected as by means of a valve 7 which communicates with any suitable source of metal either in solid or molten condition and, of course, the supply of molten metal from said crucible 4 through the tube3 into the other crucible 1 may be controlled by any suitable means such as the plunger 8 which is reciprocable in the tube 3 between positions closing and opening communication between the crucible 4 and the tube 3.

Both of the crucibles 1 and 4 are surrounded by housings 9 and 10 respectively, and said housings are formed with suitable ports 11 to which a vacuum pipe leading to a source of vacuum may be connected whereby the chambers within said housings may be maintained at a desired sub-atmospheric pressure for reasons to be discussed in greater detail in the ensuing description.

Extending through said crucible 1 and the housing 9 therearound is a tubular member 12 which is formed with openings 13 through the wall thereof at an intermedi ate portion of the length thereof so that the molten metal in said crucible 1 may flow into and fill the mold cavities bers.

I 2,787,817 Patented Apr. 9, 1957 14 defined between molds 15 in said tubular member and the inside wall of said tubular member 12, said molds 15 being adapted to be periodically advanced throughsaid tubular member 12 whereby the filled molds are advanced downwardly through crucible 1 and unfilled molds 15 are positioned in register with the aforesaid openings 13. Surrounding the lower end of said tubular member 12 is a cooling jacket 16 which is arranged to cause solidification of the metal which fills the molds 15.

Associated with the opposite end portions of said tubular member 12 is a mold feeding device 20 and a mold unloading device 21, said devices, as herein illustrated, each comprising a rotary member 22 formed with at least two openings 23 therethrough adapted, upon indexing of members 22, to register with the opposite ends of said tubular member 12. Said rotary members 22 are driven in synchronism as by means of the shaft 24 and the gearing 25 so as to align one of the holes 23 of each with the opposite ends of said tubular member and to align the other of such holes 23 of each with holes in the cover plates 26 and 27 disposed on opposite sides of said mem- Thus, when said rotary members 22 are in the position shown, a mold 15 may be loaded either manually or automatically from a conveyor or the like (not shown) into the hole 23 of the upper rotary member 22, and the filled mold with the solidified casting therein may be ejected or unloaded from the hole 23 of the other rotary member 22 as by means of the plunger 28. Further, in this position of the parts the mold 15 which was previously loaded into one hole 23 of the upper rotary member 22 may be forced downwardly as by means of plunger 29 whereby the entire series of molds 15 in said tubular member 12 are shoved downwardly with the lowermost one entering the empty hole 23 in the lower rotary member 22.

Said plunger 29 is preferably provided with a liquid seal 3i therearound and is subjected to vacuum through the port 31. In order to effect a vacuum seal wherever necessary or desirable, suitable gaskets, O-ring pack ings, or the like are employed, and in addition the cover I plates 26 and 27 on the opposite sides of each rotary member 22 are resiliently pressed thereagainst and one of said cover plates 26 and 27 is formed with a vacuum connection 32 to withdraw air and gases from the holes 23 which are in register with the opposite ends of said tubular member 12.

From the foregoing description it is evident that the entire casting process is performed under vacuum without opportunity for oxidizing of the molten metal or the solidified casting. Moreover, the vacuum is effective to degas or deoxidize the mold cavities 1.4 to assure filling of said cavities with molten metal and to insure sound castings without trapped gas pockets. Moreover, since the castings may yet be at a relatively high temperature when discharged from the lower end of the tubular memi ber 12 into the mold unloading device 21, there is provided a vacuum chamber 33 in the latter into which the mold 15 and castings 34 therein are advanced. In the completed casting ejected by plunger 2% from the mold unloading device 21, the mold 15 may be broken away to leave the finished castings 34 and of course in some instances the mold 15 may become a permanent part of the finished casting.

In addition to the use of this apparatus for casting molten metal as aforesaid, the same may be employed for sintering powdered metal briquets and in such case there will be no molten metal in crucible 1. The selfsupporting pressed compacts of the powdered metal are loaded into the feeding device 20 in the same manner as the molds 15 and are transferred to register with the upper end of said tubular member 12 and from the feeding device 20 the pressed compact may be shoved downwardly by the plunger 29 so as to be under the influence of the high frequency heating coil 35 or the equivalent which surrounds a portion of the tubular member 12. Said high frequency heating coil 35 Will heat the pressed compact to sintering temperature and the sintered compact is then shoved downwardly through the cooling zone within jacket 16 and finally into the mold unloading device 21 from which it is transferred to a position for ejection by the plunger 23.

It has been found that the performance of the sintering operation under vacuum conditions removes gases from the pressed compact and thereby enables the attainment of a better bond of the metal particles to each other and in a shorter sintering cycle. Furthermore, the vacuum sintering as herein accomplished has been found to markedly improve the electrical conductivity of the sintered briquet as compared with the sintering of pressed compacts of powdered metals by the process in common use heretofore.

()ne of the distinctive features of this apparatus is that the degassing or reacting chamber 10 and the crucible 4 therein may be used in connection with other chambers and crucibles to feed into the crucible 1 pretreated metals or other molten materials. In the ordinary degassing of metal under vacuum, the metal is inclined to splatter in particle and film form and occasionally is deposited on the walls of the surrounding chamber. Thus it is very unhandy and undesirable, and virtually impossible to advantageously degas and to cast metal continuously in a single chamber. However, the degassing of the metal in one or more separate chambers can be readily accomplished and when the metal is completely degassed that chamber full of degassed metal can be fed as required into the casting chamber, while in another separate chamber a different body of material may be subjected to degassing.

With the chamber 10 or chambers 19 if more than one is employed, it is possible to use the same as a reaction chamber for effecting chemical reactions in molten materials and for making alloys prior to casting thereof. For example, it is possible to fiuorinate under pressure in such chambers 10 chemicals which are suitable for making synthetic mica therefrom and to flow the molten material which has been melted and fiuorinated into the casting chamber so that the final casting may be made therefrom. Accordingly, the present apparatus is not only a casting apparatus but, as well, a degassing apparatus or a reacting apparatus for treating materials prior to casting thereof.

.As previously indicated, the molds 15 may be subjected to heat as well as to vacuum after being loaded into the feeding device 20. Furthermore, lamination of metal may be accomplished with the present apparatus.

While in the present case there is illustrated a mold.

15 of generally spool-type form, it is to be understood that other types of molds may be employed. For example, the molds may be ring-shaped and arranged to interfit with one another and provided with sprue openings for flow of molten metal, and said molds may have interconnecting risers between them so as to reduce the shrink to a negligible amount because the molten metal keeps shrinking downwardly and feeding the mold which is being cooled from above even after passing through the pool of molten metal. Also, the molds 15 may be invest ment molds such as shown in my copending application Serial No. 225,949, filed May 12, 1951, now matured into Patent No. 2,716,790, and it is to be understood that such investment molds may be encased or enclosed, within ceramic flasks or the like which serve to give support to the mold to permit pushing and handling thereof without danger of fracture. Such mold surrounding flask may be provided with a ceramic exterior of plaster or like material so as to secure accurate exterior dimensions for close sliding fit Within the guide tube 12.

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 the following claim, or the equivalent of such, be cmpl-oyed.

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

Automatic feed casting apparatus comprising first and second housings each defining a vacuum chamber having a vacuum connecting thereto and having molten metal therein, a conduit extending between said housings whereby vacuum degassed molten metal is supplied into said second housing from said first housing, said second housing being formed with an inlet opening for insertion of empty molds into such chamber and a discharge opening for removal of molds filled with such metal as moved through said chamber, a mold feeding device having a plurality of openings therein which are adapted to be successively loaded with empty molds, means for moving said device to successively position such openings in register with such inlet opening, means for sealing the molds in the successive openings in said device from the atmosphere, as said device is thus moved, means for evacuating such sealed openings and the molds therein, means aligned with such inlet opening to discharge the successive evacuated and empty molds from the feeding device openings into such inlet opening, through said chamber for further degassing by vacuum therein and for filling with sic-gassed molten metal, and through such discharge opening, and cooling means for solidifying the metal in the successive filled molds prior to emergence from such discharge opening.

References Cited in the file of this patent UNITED STATES PATENTS 674,685 Payson May 21, 1901 748,414 Passburg Dec. 29, 1903 1,342,127 Mellon June 1, 1920 1,822,256 Watt Sept. 8, 1931 1,822,939 Stout Sept. 15, 1931 1,999,114 Sherwood Apr. 23, 1935 2,085,450 Rohn June 29, 1937 2,094,753 Ryan Oct. 5, 1937 2,099,208 Horsfall et al. Nov. 16, 1937 2,293,400 Morris et al. Aug. 18, 1942 2,317,276 Knight Apr. 20, 1943 72,541,764 Herres Feb. 13, 1951 2,582,438 Jones Jan. 15, 1952 2,640,860 Herres June 2, 1953 2,716,790 Brennan Sept. 6, 1955

Images