US2782476A - Apparatus for casting air foils and the like - Google Patents

Description

e. 26, 1957 J. B. BRENNAN 2,782,475

APPARATUS FOR CASTING AIR FOILS AND THE LIKE Filed Oct. 16, 1952 2 Sheets-Sheet 1 I N V EN TOR. Jasfm B. arm/MW B AJ A TTOIQIVE Y5.

Feb. 26, 1957 J. B. BRENNAN 2,782,475

APPARATUS FOR CASTING AIR FOILS AND was: LIKE Filed Oct. 16, 1952 2 Sheets-Sheet 2 IN V EN TOR.

JJJEPl-l B. EMA IVAN ATTOBA/EXS.

APPARATUS FOR CASTING AIR FOILS AND THE LIKE Joseph B. Brennan, Cleveland, Ohio Application October 16, 1952, Serial No. 315,093

2 Claims. (Cl. 22--79) The present invention relates generally as indicated to an apparatus for casting air foils and the like, and more particularly to an apparatus for casting long, hollow sections, the molds for which are of such great size and weight as not to be readily capable of being conveyed or transported in the manner disclosed in my co-pending application Serial No. 202,707, filed December 26, 1950, now abandoned.

In said co-pending application, there is disclosed a method of casting wherein molds are successively shoved through a guide in fluid communication with a molten material supply crucible and thence through a cooling or solidification zone whereat solidification of the castings within said molds is effected.

Accordingly, it is one principal object of this invention to provide an apparatus for casting in which the molten metal supply crucible and the cooling means may be moved with respect to the molds for air foils or like largesize castings.

It is another object of this invention to provide an apparatus wherein the molds are progressively filled from the bottom upwardly and similarly cooled from the bottom upwardly, whereby the shrinkage effects are substantially eliminated.

It is another object of this invention to provide an apparatus by which and with which the large-size heavy molds for air foils or the like are first pre-heated, then filled with molten metal progressively fro-m the bottom upwardly, and then similarly cooled from the bottom upwardly so that the molten metal above the chilled metal accommodates shrinkage of the chilled metal, all of this being accomplished without the necessity of lifting such relatively heavy, large-size molds.

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

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

In said annexed drawing:

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

Fig. 2 is a cross-section view taken substantially along the line 2-2, Fig. 1;

Fig. 3 is a fragmentary perspective view of a modified air foil section different from that shown in Figs. 1 and 2;

Fig. 4 is a central, vertical cross-section view of a modified form of the present invention; and

Fig. 5 is a transverse cross-section view of another air foil or the like.

Referring now in greater detail to the drawings and first to Figs. 1 and 2 thereof, there is provided a base structure 1 which includes a base plate 2 supported in elevated ited States Patent in a cavity 8 of the desired cross-section which in the present case is an air foil section including skin portions 9 cast integrally together and web portions 10 extending between said skin portions and extending lengthwise thereof to form a one-piece, lightweight and strong structure. Risers 11 are included in said mold 4.

Leading into such mold cavity 8 from opposite sides and fro-m a plurality of different levels and preferably along the parting line of the mold sections 5 and 6 are gates or sprues 12 through which molten material is adapted to flow during filling of said cavity and the upper ones may be inclined as shown for a purpose as will appear. Suitable cores 13 are supported on the bottom of the mold cavity 8 and are supported in spaced relation by means conventional in the art, to define the aforesaid Webs 9 and 10 of the cast article. The mold 4 may be made of any desired material; and when made of nonconductive material, carbon plates or the like must be disposed therearound so that the surrounding high frequency coils 14 may be effective to pre-heat said mold. Otherwise, if the refractory non-conductive mold did not have any such carbon or like plates therearound, it would be necessary to use gas, oil, or radiant heating means for pre-heating the same. A preferred material for the mold 4 is stabilized zirconium dioxide.

Surrounding said mold 4 when the latter is supported on the base structure 1 is a crucible 15 for molten material which has valve plates 16 on opposite sides for opening and closing the discharge ports 17 which are adapted toregister with the gates or sprues 12 of said mold 4. The lower end portions of said valve plates 16 may be pressed against the mold sections 5 and 6 to establish fluid-tight seals as by means of hydraulic cylinders 18 or the like. Said valve plates 16 may be raised and lowered as by means of the handles 19 which are pivotally connected to the crucible 15 and to the upper ends of said valve plates 16. The high frequency coil 14 previously referred to is supported by the crucible 1S; and, as evident, said coil is effective to maintain the material in said crucible in molten condition and at the proper temperature for casting. In the case where said mold 4 is made from conductive material or of non-conductive material with conductive plates attached thereto, said coil 14 will further serve to pre-heat said mold to at least the melting point of the material to be cast thereinto, such pre-heating being preferably effected while the valve plates 16 are in position closing the ports 17. It is preferred, but not necessary, that the charge of molten material in the crucible 15 be equal to the volume of the cavity 8 including the risers 11 and gates 12 so that said crucible is emptied each time. The valves 16 can, of course, be closed when the casting operation is completed so that the excess material is retained in said crucible 15.

Secured to and extending downwardly from said crucible 15 is a cooling device 20 which, for example, has passages 21 formed therein for the flow of a suitable coolant fluid such as water, for example. Said cooling device .29 is of the same interior cross-section shape and size as the mold exterior whereby, when said crucible 15 is lifted, as through the hooks 22 and chains 23, said cooling device will closely embrace said mold so as to effect solidification of the molten material cast thereinto.

An insulating plate 24 may be interposed between said crucible 15 and said cooling device 20.

The apparatus of Figs. 1 and 2 may be operated as follows: a

With the crucible 15 and cooling device 20 in raised position above the base structure 1, a mold 4 is positioned on the base plate 2 whereupon the crucible and cooling device unit as a whole may then be lowered to the position shown in Fig. l. The high frequency coil 14 is energized and the valve plates 16 are in closed position, whereby the mold 4 is pre-heated to at least the melting point of the molten material so as to avoid any premature chilling of the molten material when the material is allowed to flow into the mold cavity 8.

After the mold has been properly pre-heated to the extent indicated above by the coil 14 or by other means previously mentioned, the valve operating handles 19 are pressed downwardly to raise the valve plates 16 and thus permit the properly heated molten material to run through the lowermost gates or sprues 12 of the mold 4' into the mold cavity 8. The material thus enters the bottom of the mold cavity 8 and flows upwardly therein and then the crucible 15 is progressively raised to cause the molten material to flow upwardly through the other gates r sprues 12 and in each instance, the material flows in an upward direction.

As the crucible 15 is thus raised, the upper end of the cooling device 20 is likewise raised whereby cooling and solidification of the material in the mold progresses from the bottom upwardly. Of course, the molten material in the upper inclined gates 12 and in the risers 11 will compensate for shrinkage. Thereafter, the crucible when raised further (with the valves 16 in closed position when material remains in said crucible), said cooling device 20 encircles the mold 4 from the bottom to the top thereof, whereby the top portion of the casting material is the last to be solidified; and during the solidification thereof from the bottom upwardly, the molten material thereabove compensates for shrinkage of the solidified metal. After the casting has been solidified in the mold 4, the crucible and cooling device unit is raised further so that the mold 4 and the casting therein may be removed from the base structure 1 and carried away for removal of the casting from within the mold.

While the article cast in the apparatus of Figs. 1 and 2 is of one-piece construction, it will be apparent to those skilled in the art that other articles may be cast or that air foils may be cast in the form shown in Fig. 3, for example, with one skin portion 25 and the reinforcing webs 26 integrally cast and the opposite skin portion 27 welded or riveted to the ends of 25 and to the webs 26.

As evident, the method and apparatus of Figs. 1 and 2 depends on relative vertical movement between the mold 4 and the surrounding crucible and cooling device unit. The same general effect of pouring metal into a mold progressively from the bottom upwardly; and, similarly, effecting solidification of the metal from the bottom upwardly may be accomplished in other ways such as illustrated in Fig. 4, for example. In this modification, there is a relative horizontal movement of the mold 4 and of the casting device 30; and it is immaterial whether the mold 4 or the casting device 30 is moved horizontally. In this embodiment, the crucible 30 is formed so that, during relative horizontal movement by raising the first gate 16 at the left, molten material is poured into the mold 4, first through the bottom sprues 12, then through the intermediate sprues by raising the intermediate gate 16, and finally through the uppermost sprues by raising the third gate at the right. The cooling device 31 is arranged so that, during such relative horizontal movement, first the bottom portion of the mold 4 is cooled and thence, as the relative horizontal movement continues,

the cooling is effected progressively upwardly to effect a solidification of the casting within the mold from the bottom upwardly to achieve the desired results aforesaid.

material or in facial contact therewith, they can remain stationary and be filled with molten material when heated by a surrounding heating means and by pouring the metal in through gates which are situated preferably along the parting lines of the molds.

With further reference to the structure illustrated in Figs. 1 and 2, it will be apparent to those skilled in the art that, if desired, the crucible and cooling device unit may be stationary with the mold carried on a vertically movable base or elevator structure 1 which is movable downwardly from the position shown to lower the mold 4 into the cooling device 20 and upwardly to raise the mold 4 above the crucible 15 for unloading and loading.

It is to be understood that the molten material may be fed into the mold 4 with a pump or a pressure crucible through flexible connecting lines to said mold, yet retaining the essential features of feeding from the bottom upward, and cooling from the bottom upward. Also the gates 12- might well be inter-connected so that feed down occurs between them and fusing also occurs.

Fig. 5 shows an alternate manner of casting of an air foil section or the like as two mating portions 35 and 36, the abutting edges of which may be lightly machined for joining in facial contact. Thus, when the castings 35 and 36 are of aluminum alloy, for example, aluminum brazing compound can be placed between the abutting faces and the assembly squeezed together in a brazing furnace or otherwise subjected to heat to melt the brazing compound. The brazing might also be effected by high frequency heating. Squeezing together of the two portions 35 and 36 is also contemplated after casting in a close fitting die heated to approximately 400 to 500 F. after the casting.

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

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

1. Apparatus for casting a relatively tall and thin wall metal article comprising a single mold formed with a cavity which is the counterpart of such article and with openings leading into such cavity at different levels commencing adjacent the bottom of said cavity, molten metal feed means supported for movement relative to said mold and provided with a supply port for successively communicating with said mold openings from the lowermost opening up for upward flow of metal in said cavity from the bottom up 'as said feed means is moved relative to said mold, heating means effective to heat the metal in said cavity as the level thereof progressively rises, and cooling means adjacent and below said heating means for solidifying the metal in said cavity, said heating and cooling means also being supported for movement relative to said mold in a direction such that the latter solidifies the metal progressively upwardly from the bottom while the former heats the progressively rising level of molten metal above the solidified metal.

2. Apparatus for casting a relatively tall and thin wall metal article comprising a single mold formed with a cavity which is the counterpart of such article and with openings leading into such cavity at progressively higher levels commencing adjacent the bottom of said cavity; molten metal feed means provided with a supply port through which molten metal is adapted to be fed into said cavity successively from the lowermost opening up,

vertically adjacent heating and cooling means respectively eflective to maintain metal in the cavity in molten condition and to solidify the metal therein and respectively disposed around at least the lower portion of said mold an daround said mold but therebelow, means supporting said mold, and said heating means, cooling means, and feed means for upward movement of the latter with respect to said mold whereby metal flows from said feed means into said cavity from progressively higher levels, the progressively rising level of metal is maintained molten in said cavity by said heating means for a relatively shallow depth below the rising surface, and the metal is progressively upwardly solidified by said cooling means beneath such progressively rising level, shallow depth pool of molten metal thereabove.

References Cited in the file of this patent UNITED STATES PATENTS 537,277 Crecelius Apr. 9, 1895 1,308,926 Burkhardt July 8, 1919 1,777,657 Stay et al. Oct. 7, 1930 1,812,172 Rohn June 30, 1931 1,841,881 Davis Ian. 19, 1932 1,999,114 Sherwood Apr. 23, 1935 2,560,639 Giesler et al July 17, 1951

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