US1670725A - Method and apparatus for forming castings - Google Patents

Description

May 22, 1928. 1,670,725 L. E. Kl-:EN

METHOD AND APPARATUS FOR FORMING CASTINGS mld'mg, 19 6 2 sheets-sheet 1 May 22, 1928.

L. E. KEEN METHOD AND APPARATUS FOR FORMING CASTINGS Filed M? 28, 1926 2 Sheets-Sheet 2 35am /feM (/@77 i071/ W05@ MKZ@ Mia/Men??? Patented May 22, 1928.

UNITED STATES PATENT OFF-ICE.

LOUIS E. KEEN, OF HAMMOND, INDIANA, ASSIGNOR IfO WANNEB MALLEABLE CABT- INGS COMPANY, OF HAMMOND, INDIANA. A CORPORATION OF DELAWARE.

METHOD AND APPARATUS FOR FORMING CASTINGS.

Appncauon ined my 2s, 192s.

My invention relates to method and apparatus for forming castings and, lnore particularly, to the formation of what may be termed generally as center core castings wherein shrinkage is compensated for hy au internal core feeder.

During the formation of center core castings, for example hub castings such as may he used for various types of vehicle wheels, and particularly immediately following the pouring operation when the molten metal is cooling and setting in the mould. there is a tendency for the metal to .shrink with the result that the mould cavity parts are not tilled out uniformly, thereby' causing a defective casting. That is to say, this shrinkage unless compensated for, causes low spots, cracks, pits Weak places, holes and other defects in the casting which may render it unfit for use.

Une manner heretofore employed 'in compensating for the shrinkage above referred to is to provide one or more so-called external feeders. These external feeders are located externally of the mould cavity and may take the form of pockets connected to the pouring passage so as to receive and hold a surplus quantity of the molten metal. The object in using such external feeders is to provide a supply of molten metal which will be feed to the mould cavity to supply the molten metal therein to compensate for the shrinkage which takes place as above explained. It has been found that this form of shrinkage compensation is not satisfactory in the formation of center core castings, particularly center core castings of considerable depth, because in the formation of such castings the tendency for greatest shrinkage appears to be at or near the center of the mould cavitv and adjacent the center core therein, with the result that the external feeder just referred to is so far removed from the point of greatest shrinkaee that the intended compensating ell'ect 1s lost. One obvious reason for this is that the external feeder is so far removed from the point where shrinkage is the greatest that the molten metal contained therein is cooled excessively thereby resisting the shrinkage draw of the metal with the result that the well-known low spots, cracks, tips and other defects due to shrinkage still appear on the interior and adjacent parts of the resultant casting.

Serial No. 112,197.

Still another manner heretofore proposed for compensating for such shrinkage is to provide the center core used in making .such center core castings with a central passage having outlets leading into the mould caritv and wherein the pouring of the moulteh metal for casting is accomplished by pouring the same directly through such central passage and thence into the mould cavity. This manner of compensating for shrinkage has been found unsatisfactory and impractical. This is mainly true because duringr the pouring operation of the moulten metal through the center of the core particles. ot' the sand forming such core are caused to mingle with the moulten metal and are carried thence directly into the mould cavity' with the result that the casting is formed with pits and sand holes and other wellknown defectswhich render such casting untit for use.

One of the objects of mv invention is to providevfor full and complete compensatioli tshrmkage in the formation ocasfings such as center core castings` wherein all defects heretofore 'experiencedTx-tlie for'nation of such castings are eliminated with the result that successive and fully formed castings may be made with a minimum of loss in time and material.

nother object is to facilitate manufactgre of center core castings-'and rtd-t-itlicost ot manufacture of the same to a minimum.

A further object is to provide for complete compensation for shrinkage by the use of clean metal supplied directly from the casting mould cavity. such metal remaining at the proper molten and feeding condition throughout the entire period of shrinka e being therebv subject at all times to rea y response to the shrinkage draw.

A still further object is to provide for the feeding ot' a compensating metal at a point compensation needs are required.

pocket therein. I also provide a single opening through the wall of the core so as to provide communication between the mould cavity in which the casting is to be formed and the central core pocket. I preferably employ a sectional 'core to facilitate manufacture of the same. This core is also provided with a vent leading into the pocket on the interior thereof for a purpose wellknown. In further carrying out my invention the casting mould and itsmould cavities are prepared inthe ordinary manner- The casting mould may be of the,usual form and may be of such construction that one or a plurality ofeast-ings may he made simultaneously. After the castingr mould has been prepared ready for the placement of the center core, the center core is placed in the mould cavity and the mould prepared for pouring of the molten metal in the. usual manner. After this the molten metal is poured through the pouring gate fromavhich it flows to the casting mould cavity surrounding the center core. The molten metal upon entering the mould cavity, also enters the pocket. in the center-core through the o ening above referred to as leadingr through the core wall. As the casting mould cavity is filled, this central pocket in the core is also filled, all of which is indicated to the operator at the pouring mouth of the casting mould. This central core pocket may be termed an internal core feeder.l Upon the completion of the foregoing a surplus of molten metal is stored inside the center core andinternally of the casting mould and this surplus metal, being surrounded on all sides by the molten metal in the mould, remains in a molten and feeding condition longer than themetal in the mould so that as the metal in the mould cools and shrinkage takes place, Such feeder' metal is in a sufficiently molten condition to freely respond to shrinkage draw. The shrinkingr metal is thereby fully and completely compensated for by the metal in the feeder whereby when the metal in the mould has cooled and the casting operati-on is complete. a fully shaped casting is formed which is free from low spots, cracks, pits, weak places, holes and other defects which would render the castings formed unfit for use. According to my invention, with the shrinkage feeder located internally of the center core, compensation is provided for through the outlet of Such feed pockets at the point. where the shrinle' age drawis greatest aml where the freatest I* urthermore,.in carrying out the foregoing operation. both the molten metal which enters the casting mould cavity and'that which enters the feed pocket in the center of the center core clean andfree from core, sand and the like, which if present, would tend to canse the defects hereinbeforc referred to.

,Fig 3 is a horizontal section taken through a casting mould suitable for mouldin aplurality of castings simultaneously, anegl showingcenter cores, such as shown in Fig. 1, in place. in the mould cavities.

Fig. 4 is a vertical section taken on line 4--4 of Fig. 3.

Fig. 5 is a side elevation of a hub castinr formed with the, structure of 1 to inclusive.

Fig. 6 is a top plan view offa cast vvhecl which has the spokes thereof cast integrally with the. hub portion, illustrating 'another application of my invention.

I have shown, and will describe, my invention as applied particularly in connection with the formation of hubs for automobile wheels suci as that shown in Fig. 5. However, I do not desire to limit my invention to such hub castings exclusively because it is obvious that the Same may be used in connection with the formation of ceuter` core castings such as the wheel shown in Fig. 6 and other castings where deep center cores are employed and Where the tendency for excessive shrinkage exists.

- Referring particularly to the drawings, the center core which I employ nia/y comprise two lhalf-core parts l and 2 which are ident-ical in form and size4 except that core half 2 is provided with an opening 3 at its central portion.l Each core half is provided with a half pocket portion so that when the two halves of the core are joined together an internal circular pocket 4 is formed therein. The opening v3 in the core half i. leads directly into thisl pocket l and serves as the medium through which the molten metal during,r the casting operation is fed bothn to and from the pocket 4. Furthermore each core half is so shaped. that when they are joined together a vent passage 5 which leads into the core pocket is formed. Then the casting operation takes place and shrinkage occurs. the greatest -shrinkage draw. and lwhere cornl'iensation for the same is needed most, is at about' the center of the mould cavity'internally thereof. Therefore.v in the center core which employ. the .so-milled center feeder or internal core which compensates for this shrinkage is located internallyv of the mould and internally of the cooling metal and the outlet or communication between'sneh feeder and the metal in the mould cavity is located at about the center of the mould cavity internally thereof at the point where the draw is greatest and where compensation for shrinkage is needed most. Furthermore, since this feeder or compensating metal in the feeder pocket 4 is entirely surrounded by the metal in the mould` it is the last metal to cool with the result that it remains in a proper molten or feeding state throughout the entire period of shrinkage and until the metal in the mould has fully and completely set to the shape of the mould.

lu forming a hub casting such as shown in Fig. 5. a castingr mould such as shown in Figs. 3 and 4 may be employed. This mould of Figs. 3 and 4 is adapted particularly for the casting of two hubs simultaneously. It may be built up in the usual manner with the use of the proper patterns to form the body G, mould cavities 7, )outing gates 8 and pouring passages 9. fter the mould G has been partially prepared in the ordinary manner by the use of patterns, the center cores are set in place in the mould cavi ties 7 in the manner and in the position shown in Fig. 4, it being understood that the casting mould 6 is preferably formed in sections to permit of ready insertion of such cores. When the center cores have been fixed in place and the mould parts properly adjusted, the mould is then ready for the pouring of the molten metal and the casting of the hub. In the casting operation the molten metal is poured through the gate 8 and it passes through the passages 9 into the mould cavities 7 surrounding the center cores and fills such cavities. As the mould cavities are filled, the molten metal also passes through the openings 3 in the center cores and also fills the shrinkage feed pockcts 4 inside such cores. Filling of the mould cavities 'i' is indicated to the operator at the pouringr gate 8, at which time pouring of the molten metal is discontinued. During the period of pouring there is naturally a slight cooling of the molten metal during its passage through the mould cavities and final cooling takes place rapidly after pouring has ceased. Durin the final cooling. the cooling met-al shrin s, the shrinkage draw being greatest near the center of the mould cavity towards the ends thereof. As the cooling metal shrinks this drawing action draws the metal from the feed pockets 4 inside the center cores through the center core openings 3 and compensates for the shrinkage and thereby maintains uniformly the section of the metal in the mould cavities so that when the casting operation is complete the fully formed casting is free from low `spots. cracks, pits and other similar defects caused by shrinkage.

The castings are removed from the mould 6 in the customary manner. In this connection another advantage of my invention may be noted in that, by roviding the pocket 4 in the center cores, tlie walls of said cores are comparatively thin, such walls being readily softened by the. molten metal so that they crumple very readily. This condition greatly facilitates the removal of the center core part from the castingr after its formation. Upon the completion of the foregoing, the casting is in condition for liual treatment for the use intended.

My invention may also be employed in connection with the formation of wheels such as that shown in Fig. ti and when-ln the hub and spokes are cast integrally. ln the formation or casting of a wheel such as shown in Fig. G, the same conditions relative to shrinkage exist and unless such shrinkage is compensated for in a definite and positive manner, the defects hereinbeforc set forth must necessarily exist. In cmploying my invention in castingr .such :i wheel, the ordinarily occurrent defects due. to shrinkage are positively eliminated.

From the foregoing it will be seen that l have provided method and apparatus for forming center core castings such as hubs for automobile wheels and the like wherein full and complete compensation for shrinkage is provided and wherein defects ordinarily prevalent in the formation of such castings are positively eliminated, at the same time, facilitating and reducing the cost of manufacture.

Having thus described my invention, what I claim 1s:

1. The method of forming center core castings which comprises feeding molten metal into a mould cavity surrounding a center core and thence internally of said center core.

2. The method of forming center corc castings which comprises feeding the molten metal into a mould cavity surrounding a center core, causing part of said molten metal fed to said mould cavity to enter the interior of said center core, permitting the molten metal in said mould cavity to cool, and compensating for shrinkage during cooling of said mould cavity metal by metal fed in a molten state from the interior of said center core to said mold cavity at substantially the inner central portion thereof.

3. The method of forming center core castings which comprises feeding molten metal into a mould cavity containing a hollow center core, feeding molten metal from said mould cavity through an opening into said center core, allowin the metal in said mould cavity to cool, an rendering shrinkage draw effective during said cooling action to cause feeding of molten metal contained in said core back through said opening into said mold cavity to maintain the section of the metal therein.

l. The method of forming center core castings which comprises feeding molten metal into a mould cavity surroundingr a center core having a centrally disposed cavil)D therein in communication with aid mould cavity. l'eeding molten metal from aid mould cavity into said core cavity. the mollen metal in said core cavity being fed back into said mould cavity during the coolin;r of the metal therein to maintain the section of said metal.

In a center core for forming center core castings'. a centrally disposed chalnber therein for receiving molten metal directly from the mould cavity in which it is carried during the casting operation` said chamber being in connnunication with said mould cavity through a single opening, for feeding molten metal both to and from said core chamber.

0. The method of forming a center core -casting which comprises forming a mould cavity and placing a center core therein, feeding molten metal to said mould cavity and thence to the interior of said tenter core to till said mould cavity and core interior, permittingir the metal in said mould cavity to cool and maintaining the section of the casting to be formed in said mould ravity during said cooling period by metal fed in a molten state from the interior of said center core to said mould cavity.

7. The combination with a mould having a mould cavity for forming a. center core casting, of a center core adapted to be carried in said mould cavity, said center core having a pocket formed therein, a single metal feed opening in said core communicating only with said pocket and said mould cavity and an air vent for said pocket.

The combination with a mould having a mould cavity for forming a center core casting, of a hollow center core having its ends clou-d, a vent adapted to communicate the hollow portion ot' said core with atmosphere, and a combined metal feed and delivery opening in said core between the ends thereof through which molten metal is fed from said mould cavity to the hollow of said core from said mould cavity and vice versa.

U. ln a core adapted to he received in a mould cavity, a molten metal receiving pocket in the core body in communication with said mould cavity only and through an opening intermediate thc ends of said core, said opening being disposed centrally ot' `said mould cavity` and means for connecting said pocket with atmospheric air.

l0. rlhe combination with a casting mould having a mould cavity therein for forming a center core casting, of an internal feeder means for compensating for shrinkage during the cooling of the metal in said mould cavity to maintain the section of the casting formed therein, said feeder means including a core having a pocket with a single feed opening adapted to be fed solely by molten metal from said mould cavity.

In testimony whereof, I have subscribed my name.

LOUIS E. KEEN.

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