US2445141A

US2445141A - Method and means for making castings

Info

Publication number: US2445141A
Application number: US448748A
Authority: US
Inventors: Peter S Hardy
Original assignee: Individual
Current assignee: Individual
Priority date: 1942-06-27
Filing date: 1942-06-27
Publication date: 1948-07-13
Anticipated expiration: 1965-07-13

Description

July 13, 1948. P, s. HARDYY 2,445,141

METHOD AND MEANS FOR IAKING CASTINGS Filed June 27, 1942 5 Sheets-Sheet '1 INSEK ING m I NAILS REMOVING DUMMY PATTERN AND LAsK SAND uowma mo RAMMiNG 5 BAKING wrru E I $urmmau uwzg INSERTING CDRES AND CLOSIM FLASK POURING COOLING OPENING nnsx AND nsmovme cas'rmfi INVENTOR Peter 6'. Hard BY ml l J ATTORNEY$ July 13, 1948.

P. S. HARDY METHOD AND BEANS FOR MAKING CASTINGS 5 Sheets-Sheet 2 Filed June 27, 1942 INVENTOR fete? .flarc ly BY ad J y 3, 1943. P. s. HARDY METHOD AND BANS FOR MAKING CASTINGS INVE Filed June 27, 1942 Peter "49 4 Mm ATTORNEYS y 13, 1948- I 5. HARDY I 2,445,141

METHOD AND MEANS FOR MAKING CASTINGS Filed June 27, 1942 5 Sheets-Sheet 5 I .INVENTOR Peter J. Hardy ATTORNEYS Patented July 13, 1948 OFFICE METHOD AND MEANS FOR MAKING CASTINGS Peter S. Hardy, Bridgeport, Conn. Application June 27, 1942, Serial No. 448,748

Claims. 1

This invention relates to the art of making metal castings, and has for its principal object the improvement of the methods and means employed in preparing the mold and in making such castings to the end that the work may be done quicker and more economical, that is, with lower costs of material and labor, and with less wastage and spoilage than was heretofore possible.

In making large and intricate castings, such as castings for the cylinder heads of' air cooled airplane engines for instance, much of the delay and difficulty has resulted from the time and effort required to prepare the mold'in such a way that when it receives the molten metal portions of the mold, for instance the thin long mounds of sand forming the space between fins to be produced on the casting, will not collapse or be bent out of shape.

Heretofore, to avoid this, it was customary for the molder to place nails in the sand to reinforce and support the core-like ridges. Even when the task of placing the nails in the sand was performed by skilled workers, a great deal of time was needed to judiciously place the nails in position, for if the nails were improperly placed they would come through the surface of the sand and make a false impression on the casting, or if an insuflicient quantity of nails were used the narrow ridge of sand would collapse in the casting operation.

In addition, when making-castings of this kind with the usual rectangular flask, a great deal of sand is consumed.

In endeavoring to solve this problem, I conceived and, upon further work, discovered the practicability of the idea that if the flask were shaped to approximately conform to the contour of the pattern, and, in consequence, to the piece to be cast, the quantity of sand required for each ,the flask, and the depths to which they are ins'erted in' the flask can be controlled by suitable mechanical gauges or other means,

With the flask of the present invention and the methods. hereinafter described of making the mold preferably with the reinforcing nails, the process of casting intricate pieces can become substantially continuous and is susceptible of straight-line production.

According to the present invention, the flask is first prepared with the supporting nails in position; then, by means of suitable conveying means, it is carried to a core-blowing machine on the ram of which a half pattern is carried. The machine is operated to place the pattern within the flask and sand is blown and rammed into the space between the flask and the pattern. The pattern is then withdrawn from the flask and the mold proceeds along a conveyer where it is treated, preferably according to the present invention, by infrared rays so that it becomes baked. This treatment is comparatively rapid,-

since there is only asmall quantity of sand in the flask to be heated and set. Necessary baked cores are then inserted in the mold.

The two halves of the mold are separately prepared as above, and after they are baked are brought together and clamped and then the complete mold is placed in pouring position on a separate conveyer on which it advances to the furnace at which place it enters a compartment and receives a measured quantity of molten metal.

In addition to the features of the conflgurated flask and method of making the mold and casting, an important feature of the present invention is the provision of a stripper plate on the pattern which is so arranged that it continues to rest on the top surface of the sand as the pattern is withdrawn and which then is withdrawn from the sand by the continued movement of the pattern. With this arrangement, the danger of the pattern knocking off the corners and edges of the thin fin-forming ridges of sand is obviated.

Not only does the flask of the present invention effect an economy in the amount of sand. required to be used, but blow holes and other troubles caused by gases conflned in the sand are minimized, since very little sand is used in making the mold,

Other features and advantages will hereinafter appear.

In the accompanying. drawings which show the present invention- Figure 1 is a diagrammatic view showing the steps of the process of the present invention.

Fig. 2 is a plan view of one-half of the moldin flask made in accordance with the present invention and adapted to be used to make a mold for casting a cylinder head of an airplane engine.

Fig. 3 is a front view of the flask shown in Fig. 2.

Fig. 4 is a side view of the flask shown in Fig. 2.

Fig. 5 is a sectional view showing the means for holding the sand-supporting nails in adjusted position.

Fig. 6 is a longitudinal sectional view showing the flask of the present invention assembled with a pattern plate and stripper plate showing the pattern being removed from the mold.

Fig. 7 is a view similar to Fig. 6, but showing the pattern and stripper plates lifted from the mold.

Fig. 8 is a horizontal sectional view taken through the assembled flask and pattern showing portions of the pattern in section and showing the outline of the stripper plates of the present invention.

Fig. 9 is a longitudinal sectional view through the flask and the gau e which is used therewith for the purpose of regulating the extent of pro- Jection of the sand-supporting nails into the flask.

Fig. 10 is a. similar view, but showing the pattern in place and the molding material blown and rammed in position.

Fig. 11 is an elevation of a core-blowing and ramming machine showing the flask of this invention used thereby.

Fig. 12 is an elevation of a mold made with two flasks of the present invention.

In making large castings, especially complicated ones, such as cylinder heads for air-cooled airplane engines, the practice has been to place the pattemon a roll over machine, then place a, flask, open on the top and bottom, over the pattern, and fill the flask with sand or other molding material. Where the pattern has deep narrow depressions, as for instance those intended to form the spaces between fins, while the sand is being packed around the pattern, nails are inserted in the sand by the molder to reinforce and support the fln forming the narrow ridges or mounds. In performing this operation, a great deal of skill and experience is required, for, unless a suflilcient number of nails is placed judiciously, these mounds will break off or collapse when the molten metal is poured into the mold. Besides, a great deal of care must be exercised so that the nails, in being placed in the sand, will not break through and contact with the pattern, for otherwise they will leave pits in the cast piece or become welded to the piece in casting it and require further work and effort inremoving them from the casting.

In view of the experience and skill required to make the mold and particularly in placing the nails in position, highly skilled, and, at the present time, scarce, labor is required to perform these operations.

Since the flask must be completely fllled with sand, except for the impression left by the pattern, in most instances a great quantity of sand is needed. This not only adds to the expense in making the casting because of the cost of the material, but also considerable labor is required in placing the sand in the flask and in handling the flask by the workman.

An important .part of the present invention com erns the making of the mold itself which is a substantial improvement over the old methods and means used, and, as will be seen, effects economies in the materials employed and in the time required to perform the work. In addition, i

4 permits the work which must be performed to be done by persons of ordinary skill and without previous experience.

To these ends, the present invention, instead of providing the usual rectangular box-like flask, provides a pair of special flasks or shells for each different part to be molded.

As shown in the accompanying drawings, the flask ill of the present invention comprises a top plate 20, bottom 2| and side walls 22 forming a receiver having an open top and closed sides and bottom.

The bottom and walls 2| and 22 may have any suitable or desired thickness, but usually will be made of such thickness as to be strong and rigid enough to properly support the molding material and molten metal considering the shape and size of the casting to be made.

The flask of the present invention as illustrated herein, is to be used with a pattern ll having a plate 23 which overlies and preferably substantially covers the plate 20 of the flask iii. The pattern elements 24 project from the plate 23 and into the flask so as to make the desired impression: in the material used to make the mold. The flask and pattern plate are brought into proper registration by aligning pins 25 on the pattern entering holes 26 in the flask plate 20.

According to the present invention, the internal surfaces of the flask forman enlarged configuration of the outline of the high points of the pattern to be used with it. That is to say, the internal surfaces of the flask follow generally the outline of the pattern of the piece to be cast, but are spaced from the pattern sufficiently to provide a layer of minimum thickness of moulding material between the flask and adjacent portions of the pattern.

For instance, as illustrated in Fig. 10, internal surfaces 21 of the flask follow generally the outline of the high points 28 of the pattern indicated in part by dotted lines, but are spaced therefrom to provide a relatively thin layer 29 of moulding material between the high points of the pattern and the internal surfaces of the flask.

Of course, as usual,' the moulding material follows the contour of the pattern. in all ,its details. For instance, shown in Fig. 10, the moulding material extends beyond the layer 29 between the high points 28 on the pattern to form mounds 30 defining flns on the casting.

Thus, according to the present invention, it is only necessary to use that amount of sand or the like which is necessary to cover the internal surface 21 of the flask with a layer 29 to protect the metal of the flask from contact with the molten metal used to make the casting and such additional amounts as is necessary to follow the contour of the pattern.

The flask of the present invention preferably also has provisions for forming any necessary sprues, vents or gates if the latter are employed and, as illustrated, the flask plate 20 has suitably shaped channels 3! to receive in spaced relation from the surfaces thereof sprue-forming portions gether and secured, after the patterns are removed and any needed cores inserted between them, and that when so joined the sprues and other similar impressions in the molding material carried by the several flasks register with each I other and form completed passages for conveying the molten metal to the main part of the mold and for the escape of air or gases contained in or formed in the mold by the molten metal.

The flask may, for convenience in handling and use, have depending

flanges

33 and 34 forming legs by means of which the flask may be supported with the plate substantially horizontal. The flanges 34 are preferably located at the end of the plate 20 as shown so that when two flasks are brought together to constitute the completed mold, they form a base for supporting the mold in position to receive the molten metal as shown in Fig. 12.

In order to facilitate the removal of the pattern from the flask after the sand is blown and rammed, the pattern plate 23 is provided with stripper plates (see Fig. 8) which have edge portions 35 following the profile of thebase of the ,pattem and finger portions 31 extending between the fln-forming flanges on the pattern. The stripper plates 35 are slidably mounted on pins 38 carried by the pattern plate and are normally urged away from the latter by means of spring plungers 39.

As the flask is being filled, the stripper plate 35 rests on the top plate 20 of the flask and over the spaces between the pattern portions and the walls of the flask, as shown in Fig. 10. When the pattern is to be removed, the pattern plate is raised as shown in Fig. 6, during which movement the stripper plates 35 remain pressed against the flask and sand therein by the spring plungers 39.

This prevents the sand from being dragged out of the flask by the pattern particularly at the end of the mounds of sand between which the fins are to be cast. The continued withdrawal of the pattern plate carries the stripper plates 35 with it as shown in Fig. 7 because of heads 4|! on the plungers reaching the bottoms of the apertures in which they are located.

The present invention, as pointed out above, provides simple and convenient means for supporting the thin long mounds of sand or other moulding material so that they will not break out or collapse when the molten metal is poured into the mold. For this purpose, th present invention provides on the flask means for receiving and holding sand-supporting nails so that they may be put in place from the exterior of the flask and by relatively unskilled labor before the pattern and flask are assembled for filling and ramming.

In the form of the invention herein disclosed as exemplary thereof, to accomplish this the flask is provided, at those points at which the sand should be supported, with apertures 4| through which sand-supporting nails 42 may pass to the interior of the flask. To hold the nails projecting the desired distance into the flask, the apertures 4| are made somewhat larger in diameter than the nails, and clamping bushings 43 are mounted in the apertures in any suitable way as by a force-fit. As shown in Fig. 5, the bushings 43 have tapering internal threads 44 to receive tapered split collars 45 through which the nails 42 extend. By screwing the collar 45 into the bushing, the collar is squeezed together and caused to clamp upon the nail and hold it in the flask in desired position.

The nails may have heads 45 to facilitate their easy handling, and the lengths of, the nails and of the bushings may be such that when a proper length nail is inserted in a corresponding bushing until the head 46 of the nail strikes the end of the bushing, the nail will project the proper distance into the flask with'its end not far under the top of the sand mound to be formed nor penetrate through the mound and engage the pattern or interfere with the proper placing thereof.

, Preferably, according to the present invention,

so that nails of all one length or of a relatively few diilerent lengths may be used, positive means for limiting the projection of the nails into the interior of the flask is provided. This means may be in the form.of a dummy pattern 41 including a plate 43 which may be placed against the flask plate 20, as shown in Fig. 9, and gauge members 49 which project into the cavities of the flask and have stops 53 located in position to be engaged by the inner'ends of the nails. The gauge members 43 are larger than the corresponding pattern portions 24 by such an amount that the stop 50 will position the nails with their ends close to but not quite reaching the surfaces of the mounds of sand forming the flns in the situation shown in the accompanying drawings.

Thus, in placing the nails in the flask after the flask and gauge are united, any unskilled person can perform the task of inserting the nails in the collars 45, pushing them inwardly until they are stopped by the gauge stops 50, and then fastening them in place by tightening the collars 45. This may be done quickly and conveniently when the dummy pattern 41 and flask together are inverted or up-ended to give access to the underside of the flask.

After the nails are properly positioned and secured, the dummy pattern 50 is removed, and the pattern plate is placed on the flask which is then ready to receive the sand or other moulding material.

In the broader aspects of this invention, the flask may be fllled' with sand or the like in any suitable manner. However, much time and effort may be saved by fillin and ramming the flask by automatic means such as a core-blowing machine.

Such a machine is shown in elevation in Fig. 11. It comprises a main frame 5|, a vertically movable table 52 (which may include conveyor elements 53), a hopper 54 for the moulding material, a blow plate 55 adapted to rest on the pattern plate, and a supply of air under pressure to blow the moulding material into the flask.

In order that sand or the like may be blown into the flask of this invention by a core-blowing machine, the pattern plate 23 and stripper plate '35 are provided with passages 55, of which there may be as many as needed, and which are located over the spaces between the pattern portions 24 and the internal surfaces of the walls 22 of the flask. The passages 56 communicate with openings in the blow plate of the machine, and through the opening and passages sand is' blown under pressure until the flask is completely filled.

As shown in Figs. 6, 7 and 10, to avoid leakage of sand between the pattern plate 23 and stripper plate 35, the former may have a pipe 51 which extends through the stripper plate and opens into the sand-receiving space of the flask.

In filling the flask, care must be exercised that air traps are not formed, and to avoid this the present invention provides air-escape passages 53 in the pattern portion 24. These may be made to communicate with the atmosphere in any suitable way. When the pattern portions 24 are hollowed out for lightness and to save material as shown in Fig. 8, the air-escape pas- 'aperturesjl in which the supportingnails 42 are 1ccatedthe clearance between the nails and the apertures in the bushings 43 being small, air

but not sander th'elike may thus escape.

To anchor the moulding material in the flask, the walls of the latter at the parting line are provided with overhanging flanges ll. These also tend to prevent the sand or the like from being forced between the top plate of the flask and the stripper plate 35.

According to this invention, the molds may be prepared and the casting made in 'a substantially continuous process in the nature of straight line production, the steps'of the process may be carried out by relatively unskilled help, and the flasks and molds made therefrom may be carried from station to station at which various operations are performed by conveyors II.

As diagrammatically illustrated in Fig. l, at the first operations the two matching flasks ll making a complete mold each with a dummy pattern 41 may be placed on separate conveyors '2. Along each conveyor, the flasks pass before operators who insert the sand-supporting nails 42 in the collars 45 to depths regulated by the dummy pattern 41 and turn the collars to lock the nails in position. One operator may place all the nails or a flask, or several operators may be employed, each placing the nails in certain of the holes as prearranged to speed-up production, I

At the next station, the dummy patterns 41 are removed. Here too, the pattern plate 23 may be placed on the flask and locked in place by the hinged locks 63, the pins 25 being employed to accurately align the pattern and flask. Then the united flask and pattern may be carried by the conveyor to the blowing and ramming machine where the unit is lifted into position, aligned with the blow plate 55, and clamped. The machine is then operated to flll the space between the flask and the pattern with moulding material. The machine is then opened and the unit passes to the next station where the pattern 23 is lifted from the flask, the stripper plate remaining in position on the flask until the pattern is loosened from the moulding material, in a roll over maangd returned to the beginnin' g of the production It will be seen that the operations which must be manually performed do not require any special mechanicalskill or training, and that, since the operations are simple and easy, they may be performed speedily and with little physical or mental effort.

chine suitably arranged to lock the pattern to the machine.

If, as is many times the case, a large number of the same pieces .are to be made, the pattern plate may, as shown in Fig. 11, be fixedly carried by the blowing machine and thus will be automatically placed in and removed from the flask as the machine closes and opens.

The flasks, now lined with moulding material,

.are subjected to heat so as to set the material. According to this invention, this is done by mov ing the flask on a conveyor under lamps I4 pro,- ducing infrared rays which, because of their penetrating effect, quickly heat the moulding material to dry or otherwise set the same.

The flasks constituting the two halves of the mold are then brought together, receive the needed cores, are superposed in proper registration controlled by aligning pins and holes 4, and'are then looked, upended, and carried to a pouring machine, preferably volumetrically' controlled, which deposits in the sprues a quantity of molten metal necessary to flll the mold. When the metal has solidified, the mold is opened, the casting is removed, and the flasks are cleaned out Above and in the appended claims. the word sand" is frequently referred to as designating the material used to line the flask to make the mold, but it should be understood that as so used the word sand is intended to cover any equivalent, substitute or suitable moulding material such as core-sand, sand mixtures, plaster of Paris, etc.

Variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.

I claim: 1. In the method of making a mold for casting metal, the steps which include making a flask with internal surfaces approximately conforming in shape to the outline of the high points of the pattern to be used in such flasks and spaced from the pattern sufllciently to provide a narrow sandreceiving space between the pattern and the flask, placing a gauge in said flask and inserting sand-supporting nails in prearranged holes in the walls of the flask to a depth determined by said gauge, and withdrawing the gauge before placing the pattern in the flask.

2. A mold for making castings of metal objects having flns projecting therefrom comprising a flask having internal surfaces forming an enlarged configuration of the outline of the high points of a'pattern of the casting to be made, a baked relatively thin layer of moulding sand carried by said internal surfaces and having relatively thin and lon mounds of sand conforming to the impression of a pattern of the casting to -be made, and straight, thin sand-supporting nails adjustably carried bythe flask, and extending through the flask from the exterior side thereof into the relatively thin and long mounds of the sand which form flns on the casting. to be made.

3. For making a mold for use in casting metal, a pattern and plate for supporting the same; an open-top flask having internal surfaces forming an enlarged configuration of the outline of the high points of said pattern, the plate of said pattern covering the top of said flask and said pattern and flask forming relatively narrow spaces between them for receiving moulding sand; a stripper plate on the pattern plate interposed between it and the sand-receiving spaces between the flask and the pattern, and movable relative to the pattern; and means for yieldingly retaining the stripper plate against thesand deposited in said spaces during the initial withdrawal of the pattern from the sand.

4. For making a mold for use in casting metal, a patternand plate for supporting the same; an open-top flask having internal surfaces forming an enlarged configuration of the outline of the high points of said pattern, the plate of said pattern covering the top of said flask and said pating the stripper plate against the sand deposited in said spaces during the initial withdrawal of the pattern from the sand, said flask having flanges partially overlying the sand-receiving space between the pattern.

5. For making a mold for use in casting metal, a pattern and plate for supporting the same; an open-top flask having bottom and side walls provided with internal surfaces forming an enlarged configuration of the outline of the high points of said pattern, the plate of said pattern covering the top of said flask and said pattern and flask forming relativley narrow spaces between them for receiving moulding sand; a stripper plate on the pattern plate interposed between it and the sand-receiving spaces .between the flask and the pattern, and movable relative to the pattern; and means for yieldingly retaining the stripper plate against the sand deposited in said spaces during the initial withdrawal of the pattern from the sand, said flask having flanges partially overlying the sand-receiving space between the pattern, and the flask and said pattern plate and stripper plate having inlet holes for permitting sand to be blown in said sand-receiving space and air escape holes into the pattern and stripper plate to permit the escape of air when the sand is blown and rammed in said sand-receiving space.

6. For making a mold for use in casting metal. a pattern and plate for supporting the same; an open-top flask having bottom and side walls provided with internal surfaces forming an enlarged configuration of the outline of the high points of said pattern, the plate of said pattern covering the top of said flask and said pattern and flask forming relatively narrow spaces between them for receiving moulding sand, said flask having flanges overlying a portion of the sandreceiving space between the pattern and the flask, and said pattern plate having inlet holes for permitting sand to be blown into said sandreceiving space and air escape holes in the pattern plate to permit the escape of air when the sand is blown and rammed in said sand-receiving space.

7. For making a mold for use in casting metal, a pattern and plate for supporting the same; an open-top flask having internal surfaces forming an enlarged configuration oi the outline of the high points of said pattern, the plate of said pattern covering the top of said flask and said pattern and flask forming a relatively narrow space between them for receiving moulding sand. said pattern plate having inlet holes for permitting sand to be blown into said sand-receiving space, and air escape holes in the pattern to permit the escape of air when the sand is blown and rammed in said sand-receiving space, and sand-supporting nails in said flask, the apertures in said flask through which said nails extend constituting bleed holes for permitting escape of air from the sand-receiving space as the sand is blown and rammed therein.

8. For making a mold for use in casting metal,

8. pattern and plate for supporting the same; an

open-topflask having internal surfaces forming an enlarged configuration of the outline of the high points of said pattern, the plate of said pattern covering the top of said flask and said pattern and flask forming relatively narrow spaces between them for receiving moulding sand; sand-supporting nails adjustably mounted in the flask from the exterior thereof and extending into the sand-receiving space between the flask and the pattern; and means for adjustably locking said nails in adjusted positions in said flask.

9. For making a mold for use.in casting metal, a pattern and plate for supporting the same; an open-top flask having bottom and side walls provided with internal surfaces forming an enlarged configuration of the outline of the high points of said pattern and having nail-receiving apertures therein,-the plate of said pattern covering the top of said flask and said pattern and flask forming relatively narrow spaces between them for receiving moulding sand; and sand-supporting nails inserted in said flask from the exterior thereof, the apertures in said flask through which said nails extend constituting bleed holes for permitting escape of air from the sand-receiving space as the sand is blown and rammed therein.

10. For making a mold for use in casting metal, an open-top flask having an internal surface forming an enlarged configuration of the outline of the high points of the pattern to be used therein; sand-supporting nails adjustably carried by said flask and extending into the relatively narrow spaces between the pattern and flask for supporting the sand; and a gauge insertable in said flask and having surfaces to be engaged by and limit the movement of the nails into said sandreceiving spaces and removable from the flask after the nails are adjusted and before the pattern is inserted in the flask.

PETER S. HARDY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS