US2135537A - Method of casting - Google Patents

Description

J. SCHMELLER, svRy Nov. 8, 1938.-

METHOD oFcAsTINQI Filed June 4,v 19435 3 Sheets-Sheet 1 ,QM mm@ mw /Nw 6 5 W rma/@Jv J. scHMELLER, SR 2,135,537

METHOD OF CASTING Filed June 4, 1935 3 Sheets-Sheet 2 Nov. 8,- 1938.

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Nov. 8, 1938. v l J. scHME| ER, sR I l 2,135,537

METHOD OF CASTING 'Filed June 4, 1935 s sheets-sheet s Fia/2.- H6. /A

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Patented-Nov. 1938 PATENT OFFICE METHOD 0F CASTING `John Schneller, Sr., Lakewood, Ohio Application June 4, 1935, Serial No. 24,900

3 Claims.

This invention, as indicated, relates to a casting,.especia1ly one formed of aluminum and its alloys, and similar metals, and to the method and apparatus for producing the same. More particularly, it comprises the production through the utilization of sand molding operations of a casting of relatively large size, including, for example, castings of aluminum and the like for cylinder heads of internal combustion engines, of substantially uniform metal texture and ne grain and freedom from porosity throughout its entire extent. The invention includes the production of a casting of this type adapted to be readily freed of auxiliary metal,`in a casting operation wherein the cope and drag mold sections are of green sand suitably supported and provided with suitable passageways for sprues, risers, runners and gates, to permit edgewise pouring of molds, as well as the successive steps in making such casting.

Heretofore it has been the practice Where large quantities of articles had to be produced rapidly without undue enlargement of the plant, to utilize `permanent molds for such production, particularly where the articles were formed of aluminum and its alloys or similar light metals. Such molds, particularly in connection with the production of automotive parts, at times involve large expense because of changes in design of such parts requiring the modification of the original molds or replacement by other molds.

Heretofore the use of sand molding to form such relatively large castings has been unsatisfactory for the reason that castings exhibited areas of porosity, or were otherwise imperfect owing to the limitations imposed by standard sand molding practice wherein the castings were poured flat. Where a casting such as a cylinder head for automobile gas engines is to be made in a sand mold, it is necessary in thelconventional manner of casting the same in a horizontal or flat casting cavity to provide numerous risers for feeding metal to the heavy sections of the casting Asuch as studV bolt bosses, to make up for shrinkage losses and. a high degree of porosity in the castings at such places. Such risers, however, tend to deform thebosses and prevent their being cast accurately to size, .and cause an excessive amount of cleaning and machining to iinish the casting. For such large castings the necessityfor these numerous risers carries with it the formation of paths or areas through the casting through which the gases, especially those from the core, escape to the risers and the volume of these gases usually leaves a residuum of gases In some instances of sand molding extensive use of chills and other appurtenances is made to assist in the production of castings of articles such as cylinder heads for internal combustion engines, parts of which adjacent the combustion chambers are required to be of very accurate dimensions.

Where permanent or semi-permanent molds are used, the freezing ofthe thin areas of the casting in advance of heavier sections is often brought about and draws or shrinks or intenal strains and cracks may result.

The principal object of the present invention is to obviate the dilculties of producing satisfactory castings, especially those of relatively large size, with sand molds, particularly with reference to castings made from aluminum and its alloys and the like.

Another object of the invention is to produce a sand mold adapted for use in foundry operations requiring quantity production of relatively large size castings on a heavy commercial scale, wherein natural feeding and natural cooling of the metal may be utilized to the full extent.

Another object of the invention is to produce a mold formed largely of green sand wherein relatively large size castings can be produced equal to the structural uniformity of grain texture and surface finish of castings produced through the use of permanent or semi-permanent mold for such articles.

Another object ofthe invention is to produce a casting which as it comes from the mold is adapted for rapid and simple finishing operations to remove the excess metal in the form of sprues, runners, gates, and risers.

A further object of the invention is to provide a molding ask wherein the sand mold sections may be formed in fiat or horizontal position with suitable passages for sprues, risers, runners and gates, and with the necessary rigidity to withstand the metal pressure and handling incident to foundry operations, and thereafter assembled and poured in edgewise or vertical position.

Another object of the invention is to provide a method of flowing metal into a cavity especially one for a casting of relatively large size within a mold formed principally of green sand in a vertical position and in such manner as to introduce no unbalanced forces tending to displace a core or other members utilized in the casting and to provide adequate space and positioning for sprues, runners, gates, and risers. and to prolated ends, said invention, then, consists of the means,I method and product hereinafter fully described and particularly pointed out in the claims.

The annexed drawings and the following description setforth in detail certain means and one mode of carrying out the invention, and one product resulting therefrom, ,such disclosed means, mode and product illustrating, however,

but several of various applications of the principle of the invention.

In said annexed drawings: Figure 1 is a top plan view, partly in section, showing the cope section of a flask embodying the'principles of the invention;

Figure 2 is a longitudinal central vertical secl tional view, taken along the line 2 2, shown in Figure 1, looking in the direction of the arrows;

Figure 3 is a transverse central vertical sectional view, taken along the line 3 3, shown in Figure 1, looking in the direction of the arrows; Figure 4 is a sectional view showing a flask member similar to that shown in Figure 3 positioned on the pattern and rammed with green sand; Y

Figure 5 is a view similar to Figure 4 showing the drag section of a mold positioned on the pattern and rammed with green sand;

Figure 6 is a sectional view of the cope and drag sections of the mold illustrated in Figures 4 and 5 assembled with the core member and positioned on one side preliminary to the casting operation;

4o Figure '1 is a view of the mold with the core and drag section of the mold removed, as seen along the line 1 1, shown in Figure 6;

Figure 8 is an end view in elevation of the mold,

as seen along the line 8 8, shown in Figure 7;

Figure 9 is a side elevation showing the cast- 'ing with attached sprues, runners, gates and Y risers;

Figure 10 is an end elevation of the casting shown in Figure 9, as seen from the left hand side;

Figures 11 and 12 are sectional views, taken along the lines II-I I, and I2 I2, respectively, shown in Figure 9;

Figure 13 is a side elevation of a casting, looking at the side opposite to that shown in Figure 9; and

Figure 14 is an end view in elevation of the casting shown in Figrue 13, illustrating the end of the casting opposite that shown in Figure 10.

In the apparatus illustrated, the molds are produced in frames and the pouring of `the molds is carried out without the use of bottom boards or plates. The flask sections may take various forms, but, as shown in the drawings, compris/e the cope section I and a drag section 2, each of which is formed of green sand which is jarred in the usual manner and then rammed by hand or preferably'with an air rammer to insure a thoroughly homogeneous compacted mass which will withstand the handling and pouring operations.

Each of the mold sections comprises preferably a metal frame formed of side and end members securely fastened together by means of bolts 3 or other fastening elements, the end members being provided with handles 4 and pairs of alining lugs 5 at one end and alining lugsS at the opposite end. The alining rlugs 5 are formedY in pairs vwith alined 'perforations through which pins 1 are adapted to be engaged, and the alining lugs 6 are preferably formed singly and of greater thick- 5 ness and with accurately formed slots to receive alining pins 3.

The 'end frame members of the drag section are provided adjacent their'rearward portions with short flanges or lugs II formed with slots I2 l0 to receive clamping bolts I3 having wing nuts I4. The clamping bolts I3 are of a length sufllcient to engage the slots of similar lugs I5 formed with slots I6 provided adjacent the upper edges of the cope section of the flask, whereby the cope and l5 drag sections may be securely held together, as shown more particularly in Figures 6, and 8.

vCentrally of the front edge of the cope and drag sections of the flask and adjacent the upper e margins thereof, similar slotted flanges or lugs 20 I1, I8, respectively, are provided which receive the clamping bolts I9 with the wing nuts 2I. 'I'he meeting edges of the flask members may be formed with short reinforcing flanges 22, 23, and similar flanges 24, 25, may be provided about the 25 peripheral portions of the side and end members.

--The side members provided with the-centrally positioned lugs I1, I8, constitute the top of the flask when the sections are assembled.

When a casting of substantial length and rela- 30 tively narrow width and height, such as a cylinder head for automobile engines, is to be cast, two sprue passageways are preferably provided and the side plates having the central lugs are then formed with reinforcing bosses 26, 21 on oppo- 35 site sides of the pouring apertures which are preferably suitably beveled to provide a funnellikeopening.

In -order to insure precision operations with castings measuring accurately to size with close 40 tolerances, supporting members yfor the green sand molds are provided, such supporting mem. bers being in the form of bars or plates 3| extending transversely of each of the flask sections at substantially equal intervals throughout the 45 extent thereof with their intermediate portions reinforced by centrally positioned bars or plates 32. The cross bars 3| may be secured to the side members of the flask by means of bolts 33 or the like, and the intermediate bars or plates 32 are 50 preferably welded to the transverse bars. All of the bars are preferably formed with perforations preferably in the form of round holes of medium size and distributed substantially uniformly throughout their extent. The bars or plates 32 55 are preferably of narrower extent than the transverse plates 3|. The lower margins of the plates 3I and, where necessary, of the bars 32 are shaped .to conform to the casting cavity without projecting through the surface of the firmly com- 60 pacted sand forming the inner face of the casting cavity. The edge of each of the partition members or bars is preferably formed with sand engaging holes of somewhat lesrs than full circular vextent so as to interlock with the sand of the 65 mold and securely hold the same.

'I'he portions of thelowe edge of the partition bars or plates intermediate the marginal interlocking holes are preferably bent out of the plane of the plate in which they are formed, each ad- 70 jacent portion being turned in an opposite direction and thus serving further to support the adjacent sand of the mold close to the casting cavity. This construction with a suitable disposition of the transverse bars and the reinforcing 75 intermediate bars provides an extremelyl rigid reinforcement for the sand of the mold and permits the casting to be made without the use of side or bottom plates. The sand while of high permeability to the gases is very rigidly compacted and, as stated, is preferably rammed with air rammers. to very accurately conform to the outlines of the pattern and to maintain such position after removal from the pattern and throughout the assembly, sidewise turning, and pouring operations required for the completion of the casting.

The cope vand drag sections i and-2 are separately superimposed upon the respective patterns 34 and 35, and after the ramming of the sand as stated, the mold sectins are inverted and the patterns withdrawn in the conventional manner.

In the mold illustrated, a hollow water cooled cylinder head is shown as the article being' constructed, and a baked sand core 4I is provided. Said'core is formed with a series of prints 42, 43, which engage recesses in the mold or the drag section and form water-passageways through the cylinder head. The central print 42 is prefer'- ably formed with a central aperture 44 extending through'the print and-adjacent core, and the core is provided with a countersunk recess 45 concentric with the recess 44 to receive the head of a wire nail 46 when the shank of such nail is -engaged through the print and into the green sand of the drag section. Through the use of a large nail or like securing device, the core may be securely engaged against the ,drag section of the mold preliminary to the assembly of the cope section thereover. 'A small portion of core mud may be placed over the head of the nail to retain uniform spacing for the wall thickness of the casting. The baked sand core may also be held in position by means-of a chaplet interposed between the baked sand core and the cope section in the event that such method of supporting the core is deemed preferable for certain types of castings. The other prints 43 are preferablyv vented through the sand of the drag section through the use of wires forced through such sand in alinement with the prints. The use of a nail inn holding the core in position avoids all danger of leakage caused by imperfections in the casting when chaplets are used, inasmuch as the cold metal of the chaplets at times causes what are known as chaplet leaks in the finished casting which are usually of a character which cannot be patched up by ordinary methods and may involve the rejection of the casting.

In addition to the casting cavity for the cylinder head or like object, passageways for sprues, runners, gates and risers are formed in the mold adjacent the casting cavity. Where a relatively large article such as a. cylinder head for automobile engines is` to be cast from aluminum or like metal having a high heat conductivity and large crystallization shrinkage, the casting operations have to be arranged to vavoid the inclusion of porous metal in the casting proper, as well as to avoid draws and shrinks and surface pitting. With a casting of the type referred to, the forming of the mold sections is carried on in a horir zontal position, the cope section of the mold in the case illustrated .having the greater portion of the casting cavity 5l and the drag section of the mold having the lesser portion of the casting cavity 52. The lpouring or sprue passageways 53, 54, are provided adjacent the end members of the flask sections and are formed one half top row of bolt hole bosses 63.

in yeach. of said sections along the parting line. The sprue passageways terminate in depressions 55, 58, at opposite ends of the flask adjacent 4the parting line and connect with a runner 51 which is at the bottom of the flask when it is turned on itsside to pouring position. The runner 51 will be referred to as the bottom runner, and the metal ows through the sprues and into this runner and thence into the casting cavity through a pair of thin gates 58, 59, rising progressively on opposite sides of the core and completely filling the 4casting cavity, including the recesses for forming the bolt hole. bosses, and thence ilowing upwardly into the riser cavity 5I.

The riser cavity 5I is made of large capacity and preferably is provided with a series of channels 52 communicating with the cavities for the The riser cavity is enlarged adjacent its upper edge and has a relatively narrow vline of connection with the upper margin of the casting cavity. The ends of the riser cavity are connected with the respective' sprue passageways 53, 54 heretofore described by short vrunner passageways 64, 65 extending upwardly into the ends of the riser cavity. These runner passageways insure an adequatesupply of hot metal to the large riser cavity and insure adequate metal pressure upon the upper margin of the cylinder head or other article being cast to eliminate too rapid cooling of the metal with the inclusion of gases which would result in porosity at'such point. The riser the parting plane of the mold sections.

As has been indicated, the cope and drag sections of the fiask are formed of green sand which is very thoroughly compacted through the usual jolting operations followed by the use of hand or air remmers. The sand is thus thoroughly united in a rigid mass with the intervening perforatedbars or plates interlockingly engaged therewith. The sand has free permeability having no side or bottom boards, and the casting cavity being of such shape and position during the casting operation that the tendency of -all gases, including such steam and other gases as are occasioned through the contact of the hot metal with the green sand, is to find free escape at every point throughout the sides of the mold sections as well as through the riser cavity and the parting plane of the mold sections.

Adequate heat and adequate metal to make up for'shrinkage losses is provided through the enlarged riser 1| formed at the top of the casting proper. As has been stated, the riser is connected with the upper margin of the casting 12 by means of a narrowed portion 13, but in a large casting this portion is of a size that requires a sawing operation or the like to remove the same. The remainder of the accessory metal, however, may be readily removed by first breaking the runners 14, 15 at either side of the riser and then using the sprues 16, 11 as a pair of levers to fracture the gates 18, 19 at the bottom of the cylinder head casting, which gates,

' cavity is vented to the necessary extent through as is clearly shown in Figures 1l and 12, are very The method included in the invention comprises the steps of forming the casting cavity, together with the necessary passageways for sprues, runners, gates and risers, in complementary flask sections for a. green sand mold, wherein the sand is rigidly compacted in each of said mold sections in a horizontal position and supported so as to maintain its configuration without distortion under the required metal pressure, and thereafter assembling the complementary mold sections and turning the same to vertical position and pouring metal into said mold to fill the saine progressively from the bottom along a relatively narrow edge portion of the casting cavity. 'I'he method also includes the utilization of thin gates at the bottom of the casting cavity and the formation of a casting adapted to be freed of its accessory sprue and runner metal by fracturing the runner metal connected with the riser and yutilizing the sprues and bottom runner as a lever for fracturing the thin gates independently of any auxiliary trimming apparatus for thefcasting.

'Ihe advantages of the method above set forth may be readily appreciated when the casting of a cylinder head in conventionalA manner in a horizontally positioned casting cavity is considered. In such horizontal casting cavity it is necessary to provide an individual riser over each of the stud bolt bosses to avoid shrinkage with the consequent porosity in the finished castings at such places. This in turn often results in deformation of the bosses and prevents their being formed accurately to size, as is possible with the method and apparatus above set forth. The removal of the individual risers over each of the stud bolt bosses requires sawing or other machining operations and involves a large amount of time and labor.

Underthe present practice in casting in sand, a standard aluminum four-cylinder head for one bank of cylinders of a V-type eight cylinder gas engine having 21` stud bolt bosses, each of said bosses requires, when'the cylinder head is cast in at position, an individual riser to insure a satisfactory quality of metal at suchyfplaces toi prevent leakage through porosity of the metal and,

other defects introduced through shrinkage effects. With the method herein set forth, the accessory metal is connected with the casting only atlahe lateral margins thereof, and at one of said margins, as stated, such accessory metal may be readily broken away by reason of the thin gates employed. Thus, for each completed casting there is involved merely the removal of the riser metal by means of a sawing operation along a straight line, so that the finishing operations are reduced to a minimum, and a high rate of production can be maintained with a minimum of loss of time and materials. y v

Other modes of applying theprinciple of my invention may be employed instead of the one explained, change being made as regards the means. and the steps herein disclosed and the forms of the product resulting therefrom, provided those stated by any one of the following claims or their equivalents be employed or embodied therein.

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

1..A method of producing castings from sand molds comprising the steps of :firmly ramming sand into complementary sections of a flask While such sections are in a horizontal position over the pattern to provide a casting cavity with a lriser cavity associated therewith and sprue and tive position to form the metal passageways,v

turning said iiask to vertical position on one edge With the sand forming the sides free of enclosing members to permit free escape of gases therethrough, and pouring metal into the sprue and associated passageways to form the article.

2. A method of producing castings from sand molds comprising the steps of firmly ramming sand into complementary sections of a flask while such sections are in a horizontal position over the pattern to provide a casting cavity with a riser cavity associated therewith and sprue and runner cavities substantially in the plane of the casting cavity and spaced from the marginal areas of the casting cavity with the runner cavity communicating with the bottom of the casting cavity through a narrow gate forming a thin frangible 4 web of gate-metal with a sharp angular portion at an intermediate point thereof, supporting said sand at distributed points throughout the mold area and in close proximity to the face of the casting cavity, inverting one of said complementary mold sections and assembling the core therewith in horizontal position, assembling said complementary mold sections in alined and clamped relation with said respective cavities in coopera-'- tive position to form the metal passageways, turning said flask to vertical position on one edge with the sand forming the sides free of enclosing members to permit free escape of gases therethrough, and pouring metal into the sprue and associated passageways to form the article.

3. A method of forming hollow .castings of relatively large size, which comprises.' the steps of assembling complementary mold members formed of green sand throughout, with the casting cavity in edgewise position, and with a core member having a core print projecting from one side thereof for engagement in a recess in one of the mold members, and holding said core print to one only of said mold members by inserting a headed nail with the head engaged in a recess in the core and with the body of the nail extending through a recess centrally of said print and `with the op'posite end thereof engaged in said adjacent mold member.

JOHN SCHMELLER, SR.

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