US1789943A - Method and means for casting - Google Patents

Description

Jan. 20, 1931-. v D. 'H, MELOCHE 1,789,943

METHOD AND MEANS FOR CASTING Filed Sept. 25. 1926 5 Sheets-Sheet 1 INVENTOR 19M [MW fif' TTORNEY Jan. 20, 1931. p. H.MELOCHE 1,789,943

METHOD AND MEANS FOR CASTING Filed Sept. 25, 1926 3 Shnets-5heet 2 fi x. as a1 a4 as 1518' 2516 24 15 as 1a 25 2431 INVENTOR ORNEY Jan. 20, 1931. D. H. MELOCHE METHOD AND MEANS FOR CASTING Filed Sept. 25, 1926 3 Sheets-Sheet 5 INVENTOR ATTORNEY Patented Jan. 20, 1931 UNITED STATES PATENT OFFICE DANIEL H. MELOCHE, orBRoNXvrLLn; new YORK,. ASSIGNOR TO AMERICAN BADI- ATOR company, on NEW YORK, N. Y., A CORPORATION OF NEW JERSEY METHOD 'AND MEANS FOR CASTING Application filed September 25 1926. Serial No; 137,642.

My invention relatesbroadly and generally to new and useful improvements in methods and means for the casting of metal objects, and particularly to casting of pistons and similar elements for use in internal combustion engines.

In the production of cast metal pistons for internal combustion engines, it is generally recognized to be highly desirable to produce 1 a casting which will be of light weight, accurately cylindrical in external contour, hav ing a relatively thin metal line of uniform thickness, and which will require a minimum amount of machining to render the'casting available for installation. It is also desirable that such a casting be as free as possible of internal strains so that the same will not crack when being machined, or subjected to heat effects inservice. 7

So far as I am aware, all prior available methods employing sand molds for casting metal pistons have required theuse of cope and dragmold sections containing matching sand prints to form a mold, and the locating of a suitable core or cores in the mold, the cores being either part of the sand mold in the cope or drag, or separate from the cope and drag molds and suported in the mold by suitable means. While such methods have been used commercially, the use thereof has been attended with objectionable results, arising'mainly from core shifts, swells in the casting, and occluded gases and internal strains in the casting, all of'which resulted in non-uniformity in metal line, contour and weight, and in imperfect castings unfit for machining, or which cracked, due tointernal stresses, resulting in a large loss. Furthermore, the prior methods have necessitated that the casting be made heavier and of a much thicker metal line-than required in the finished or machined piston, so as to assure enough metal. in the casting so that when finished it would meet the requirements of the specifications for the finished piston, so far as dimensions were concerned.

By the known methods it has been practically impossible to cast largevnumbers of pistons whichg will be of uniform, weight,

der the castingsready formachining, such,

for example, as snagging sprues and grinding off fins, ridges or other ercrescencieson thecastingwhich were unavoidable in the old method of molding with cope and drag, and resulted from the diliiculty of making all cope and drag moldsmatch accurately.

A further object is to produce castings of the character mentioned, which will be free of objectionable internal strains which result in cracking during setting of the casting,

during annealing, when machined, and when in service in an internal combustion engine.

A further object is to produce castings uniformly free of occluded gases, and therefore non-porous so as to reduce lossincidental to the occluded gases or porosity, and which can usually only be discovered after the casting has been partly or wholly machined, or when it is'subjected to the stresses attending use.

A further object is to provide an apparatus which will successfully attain the objects heretofore set forth.

The invention consists in the novel method and apparatus for carrying the same into effect, to be more fully described hereinafter, and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawings I have illustrated a preferred embodiment of an apparatus constituting my invention, and wh1ch constitutes one means-for carrying my improvedmethod into effect. I

Figure/ 1 is a perspective View of a fiask employed in the practice of my invention;

Fig. 2is aperspectiveof a pattern element ll mpley d carryin t. t e inve n; i

' ton casting.

Fig. 3 is a top plan view of a core support and positioning member;

Fig. 4 is a perspective view of a preferred form of core;

Fig. Eris a perspective view of a holding member for holding the cores in position in the core-supporting element shown in Fig. 3;

Fig. 6 is a longitudinal sectional view showing the elements illustrated in Figs. 1, 3, 4c and 5' assembled for the pouring of a mold, and

Figs. 7, S and 9 are detail sectional views showing the steps of performing the method previous to the assembly of elements shown in Fig. 6.

Before proceeding with a detailed description of my invention, I would state that I have shown the same as embodied in an apparatus capable of providing for multiple casting, so as to permit the economical and rapid production of a number of castings simultaneously. However, the invention is not to be limited to multiple casting, as it contemplates embodiment in either single or multiple casting. In carrying out my invention in its preferred form, I employ a flask or mold 1, which is preferably rectangular in construction and open at its top and bottom. This mold box is preferably of a depth sufficient to hold sufficient sand to form a sand mold for molding an entire pis- The top and bottom edge, faces of the mold box are preferably made to lie in exact parallel planes in order to effect the result to be hereinafter described. Opposite walls of the flask are provided withextei sions or lugs 2, provided, respectively, with guide apertures 3, there being preferably a pair of such guide apertures in each lug, said apertures being adapted to receive guide means preferably in the form of pins carried by a pattern-carrying element, and also by a core-supporting element to be hereinafter described.

4 designates a pattern element, preferably consisting of a flat plate or board, carrying on one side thereof patterns 5 of such shape or contour as to form in a green sand mold prints or cavities corresponding to the external configuration it is desired to impart to the casting. In the present embodiment each of these patterns is a true cylinder arranged with its longitudinal axis at right angles to the plane of the face of the pattern board, and symmetrically spaced thereon.

The pattern board is provided with guide means preferably in the form of spaced pins 6 adapted to cooperate with the openings 3 in the lugs 2 to accurately position the patterns within the flask 1 when the pattern element is applied to the open end of the flask (see Fig. 7 It will be understood that in the preferred form the apertures 3 in the lugs 2 on the flask and the pins 6 on the pattern board are so located that the pattern board is reversible end for end with respect to the flask, so that the, patterns will occupy a determined and accurate position in the flask. In forming the sand mold or print in the flask, the flask 1 is arranged on a suitable support with the lugs 2 uppermost, and the pattern board 4; is then applied to the upper open end of the flask, being guided and held in position by engagement of the pins 6 thereon with the guide openings on the flask (see Fig. 7 It will be understood that the under face of the pattern board is made preferably flat, and at right angles to the longitudinal axis of the patterns, so that when the pattern board is applied in position the pat terns will project into the mold-containing portion of the flask. It will be noted that these patterns are of such length that they terminate short of the bottom of the flask when in the position just described, so as to provide a casting space to form a piston.

The pattern board having been located on the fla sk as just described, the flask 1 is rolled over by any suitable agency, so that the pattern board 4 is located on the bottom of the flask with the patterns projecting upwardly in. the latter (see Fig. 8). Mold-forming sand T'is then placed in the flask and is rammed or packed therein about the patterns, and then any suitable means is employed to level the sand in the flask. The sand may be rammed, or packed by hand, or by any well known jolt, or squeeze mechanism. After striking of the mold a suitable bottom board 8 is applied thereto, the bottom'board and the pattern board being held to the flask by any suitable means (not shown). The mold is then rolled over to bring the pattern board uppermost, as shown in Fig. 9, and the pattern is then drawn by any suitable means to separate it from the mold in the flask. As the result the flask contains a sand mold containing one or more cylindrical cavities or prints 9 which establish the external contour of the casting to be made. It will also be noted that each of these prints forms the external contour of a complete cylindrical piston casting, and that the print is located with. its longitudinal axis at right angles-to the plane of the upper edge of the flask and the face of the body of sand in the flask. Each of the prints in the mold is then ready to receive a core adapted to cooperate with the print 9 to form a casting, and in its'preferred embodiment may form additional parts, for example, the gudgeon pin bosses for receiving the pin for connecting the finished piston to a piston rod. In its preferred embodiment the core consists of a baked or dried sand body formed according to any suitable formula of sand or other material, and binder adapted for the purpose. The core is preferably hollow, including a body portion 10 of such diameter and length that when inserted in a print, above deing space 9 between the core and the print, "and is also formed with meanswhereby the fillet 11 at the juncture of the, head and skirt of the piston casting (see Fig. 6). At a point intermediate its ends the body portion may be provided with diametrically opposite recesses 12, which when the core is in position in the-print communicate with the annular space in the print and receive the metal to provide the casting with internal bosses 12 to receive a gudgeon pin for connectina the finished piston to a piston rod.

At its upper end the core is formed with suitable means for closing the annular castcore may be supported by an end at a point external of the print and the sand mold in the flask.

ential shoulder or flange 13 having a preferably horizontal under face 14 extending laterally from the core and of such width radially that when the core is in position in the mold print said face extends beyond the edge of the print and cooperates with the mold to thereby close the annular space between the core and the print, and define the bottom edge of the skirt of the piston casting. By the shoulder 13 the casting space 9 is separated or insulated from the core-supporting means to be hereinafter described, and chilling of the casting which might result in objectionable internal strains, from contact with said means, is obviated. Thecore may be formed adjacent the face 14 with anannular recess 14 to provide for an internal reenforce for the skirt of the piston casting.

The said supporting means carried by or forming. part of the core, comprises a head 15, also integral with the core, beingforined of the same composition material, and in its preferred form; is aslaterally projecting member 16, preferably circular and locate-d above projecting beyond themold or printclosing shoulder 13. The center of the sup,- porting head 15 is coincident with the longitudinal axis of the core, and the projecting part thereof is made equidistant from said center at all points to facilitate adjustment, as will be hereinafter described. The periphcry of the member 16 is beveled downward andinward, as at 16. The core is preferably made hollow, and in its preferred embodiment is formed with an axial cavityf18 which opens at its top through the upper end of the core and terminates at its lower-end, preferazbly 1 at a point below the. boss-formingre The said means for closing the annular space preferably conslsts of a circumfer- I cesses- 12 heretofore described; I provide for gating the mold,'preie-rably by forming one or more pouring ports 19 cominunlcating with the said p0 ring cavity andopening through the wall of the core into the said recesses', so that w ien the metal is poured into the cavity it flows through said ports intothe recesses and into the space in the print around the core.

I provide means its end portion or head, heretofore described, which projects above or beyond the mold .or flash, and for accurately centering and holdmetal linefor the skirt of the piston casting is assured. This means preferably consists of a rigid member in the form of a plate 20 adapted to lie over and cover the top of the mold, and having guide and positioning pins 2'1 accurately positioned thereon to correspond to the position of the pins 6 on the pattern board, and the guide '0 )enings 3 in the flask. This plate carriesmeans for sup porting one or more of said cores so as to center the latter accurately in the print, and

forthis purpose said plate is provided with one or more apertures 22 shaped to conform toor. match the periphery of the supporting head on the core, saidapertures being preferably circular and of such diameter that the wardly extending annularfiange QS-having horizontal supporting shoulder or face 24 upon which the supporting shoulder 17 on the core rests, and said flange is provided with a circular fac 2?, preferably inclined inwardly anddownwardly to engage the correspondingly formed face 13 on the print-closing shoulder of the core. The-wall of the aperture above the shoulder is beveled inwards at 24 It will thus be seen that when the plate is applied to the mold with its apertures over the print in the mold, a: core may be inserted through each said aperture to locate the body of the core in the print, and

that when the core is so located the printclosing face 14 will pro ect laterally over the edge of the mold in the flask; the'inclined.

face 13 will contact the inner annular face 25 in the aperture, and the face 17 of the shoulder 16 will rest upon the shoulder 24 in the wall of the aperture. The face 16 on the core will seat against the beveled face 24 in the.

wall of the aperture. By accurately forming the inner wall of the plate aperture, the "shoulder 24 and the cooperating face 17 on the core, and'also theinclined faces on the core and v aperture,"the core when insertedinc for supporting the core by ing the core in the print so that a uniform position to be supported by the plate will be accurately centered within the print and thereby assure a uniform metal line for the shirt and head. The cooperating inclined faces on the aperture and core head cause the core to be automatically centered in the aper tur and print.

In the preferred form means is provided for holding the cores in the position just described to assure that they will not be dislod d, due to pressures gen rated in the mold when the latter is poured. For this purpose the upper end or head of the core is preferably made of such vertical thickness as to provide a horizontal face 28 in a plane at right angles to the longitudinal axis of the core and located above the upper face of the core-supporting plate :20, and the cores are held down by suitable means, as a weighted member, preferably in the form of a plate 29 aoapted to rest upon the horizontal faces 28 when the cores are in place in the plate 20. This plate 29 is provided with pouring openings 30 which are located overthe pouring cavities 18 in the cores. it will thus be seen that the cores are held from lateral movement in the prints due to pressures generated in the print, and that the plate 29 prevents longitudinal displacement of the cores from the prints. It will also be seen that the part 13 on the core which overhangs and closes the upper end of the print separates the mold cavity and therefore the molten metal therein, from access to and contact with any part which might act as a chill for the lower edge portion of the skirt of the piston casting. lVhen the core is in position it merely contacts or rests lightly upon the edge of the mold and does not crush or break down the mold. This is accomplished by making the shoulder 13 of a proper thickness to effect the result stated. It will also be seen that the cores are supported by means which is external tothe mold in the flask, so that deformation of the mold print due to any cause, cannot disturb the accurate position of the core in the print.

In carrying out the method, the supporting means consisting of the apertured plate 20 is adjusted over the open end of the mold and is accurately positioned thereon relative to the print by means of the cooperating guir consisting of the pins 21 and apertures The cores are then dropped into place and are automatically centered and held in proper position relative to the print or cavity, due to the formation of the cooperating faces on the cores and said supporting )lZIlIG. By m1. .ing the apertures in the plate and the supporting part of the cores circular, the cores may be app ied without regard to a y particular circumferential relation to the print, as they will be accurately centered no matter what angular position they bear while'being inserted. The holding member or weight 29 is then located over and upon the upper ends of the cores, so that the latter are rigidly held on the supporting plate, whereupon the metal is poured through the apertures 30 in the holding plate into the cavities in the cores to form the casting (see right-hand mold in Fig. 6). Bythe use of the memb 29 and the manner of supporting the core by the plate :20, the core is held against movement in both directions longitudinally of the print. lhe casting A is subst tiaL-y cylindrical, including the head B and cylindrical skirt C open at the end opposite to the head, and having the internal bosses 12 heretofore mentioned. The sprue in the centralpouring cavity of the core is indicated at D, Fig.6, and is connected to the bosses by tie metal in the pouring ports or gates 19.

In order to assure the greatest accuracy and permit replacement in case of wear, each of the apertures in the supporting plate may be lined with rings or liners 31 having theconfiguration above described for said apertures, this provision permitting ready replacement in case said liners become worn or defaced so as not to accurately center a core; but it will be understoodthat the supporting faces may be made either integral with the plate 20 or bymeans of such liners just decribed. Theopenings 3 may also be lined, if desired, with replaceable bushings 3.

By the above method and apparatus I am able tovcast a metallic piston with practically any desired uniform thickness of metal line, but the invention is particularly useful-in casting pistons to a specified weight with a comparatively thin metal line, inasmuch as the accurate positioning and holding of the cores enables, me to obtain a thin metal line which will be uniform at all points and-not greatly in excess of that of the finished product, so that a small amount of machining is necessary. It will also be seen that the metal. line beinguniform, the piston may be machined, as, for example, cutting the grooves for piston rings to the proper depth without danger of cracking or cutting through thin parts, which were liable to occur incident to the old methods.

It will also be seen that by casting the complete piston in the drag section of a mold, the casting will be truly cylindrical, requiring little machining, and be free from ridges which result from parting lines in sand molds of the cope and drag type. or ridges due to non-matching of molds of the cope and drag type, which it is diflicult to avoid.

The method and apparatus provides not only for casting of pistons which will be cylindrical, of uniform metal line, light in weight, and free from internal stresses, but

also provides, in the case of multiple casting,

uality of thecastingbut reducing the costdue to saving of metal, and due'toilow losses;

head, whichwas'not possible in ililSiOlCl methods. where it was required to considerablyoverweight the casting'in order to as Lire sufficient metal line to machine it to specincation. By providing a thin uniforinmetal line for the casting, it is possibleto machine the same to a thickness of or" an inch in the finished piston, the macl'iiningloss being reduced from at least per cent. to an average loss of about one per cent. 7

What I claim and desire to. secure by Letters Patent of the United States is:

1. A molding apparatus of the character described comprising a flask body containing a sand mold having a print to form the external contour of a complete substantially cylindrical piston, a sand core in said print and coaxialtherewith, said core having at one end a sand part cooperating with the sand mold to close the opening into the print, and also having a circumferential laterally projecting supporting part at said end, said supporting part being vertically offset from said closing part, and means sup ported by said body and positioned external to the mold for engaging said supporting part to hold the core against lateral and longitudinal movement in the print.

2. A molding apparatus of the character described comprising a flask body containing a sand mold having a print to form the external contour of a complete substantially cylindrical piston, a supporting plate member overlying the mold and external thereto, said supporting member being supported by said body and having an aperture therein over the print, coacting means between said body and said supporting member for maintaining said aperture in a determined relation to the print, and a core in said print, said core and member having cooperating means whereby the core is supported in said aperture and maintained against lateral movement in the print.

3. A molding apparatus of the character described comprising a flask body containing a sand mold having a print to form the ex ternal contour of a complete substantially cylindrical piston, a supporting plate mem ber overlying the mold and being supported by the flask body and having a shouldered am able to cast a piston aperture therein; means; between the flask y-an t e uppr n i m or; in-, taining the apertureini the latter in a deter;

mined 'r elation toQtheprint, and a. corezin d-"P n a xi l he e th an hav ng a part engaging said shouldered aperture-to support the weight of saidcore from said body to prevent injury to said sand mold and whereby the core is held against movement in the print. p y

4. A molding apparatus of the character described comprising afiask body containing a sand-mold having a, print to form the external contour of a complete substantially cylindrical piston, a supporting plate mem{ ber overlying-themold and having a shouldered'apertureforguiding a core into and centeringthe axistof. the core coincident with the axis of the print, a core in said print and having apart external to the print and located in said shouldered aperture to hold thecore coaxial withthe print,.a-nd meansfor engaging-said core part to-hold the same.

against longitudinal movement inthe print, o

said last-named means including a weighted member, engagmg the pro e ct1ng endot the, core. 7

5.; A molding apparatus. ofthe character described comprising aflasklbody containing a sand mold having a print to form the external contour not acomplete substantially cylindrical piston, supportin g-means removably mounted on, said body and overlying said-mold andihaving ashouldered aperture therein to receiveand guide; core; intosaid-L print, core coaxial with said printan dehave ing. an-end portion extendingexternally of the print andhavingat its end external to the, print asand part engagingsaid shouldered: aperture whereby the core is held. against lateral movement ,inithe print and removably. supported inthe'aperture, said core-having alongitudina-l pouring; cavity gated through- U thesidegv all of thecoreinto the print, and means overlying said supporting member and engaging the external vend of theycore to hold the latter against longitudinal movement in the print,-:s,aid,last-named means having a pour-ing aperture; communicating with the cavitylinthe'corea 7 I V 6. A molding-apparatus of the character described comprising a flask body containing a sandmoldihavinga print to fOIll'LilllQ ex:- ternal contour of-a complete substantially cylindrical piston, a supporting; platefmember removablymounted on said body and overlying: the mold and, external thereto an d having; an aperture therein. over the print, coactingguide meai isonsaidtbody and said; supporting member for positioning and, maintaining: said aperture in a determined relation to the print, a. core insaid print and; extending through theaperture in said member, and coact-ing, faces: on the member and. core for. centering the core in the print,-

Eli)

7. A method of casting pistons, which coinprises forming in a flask a sand mold having a cylindrical print for the external form of a complete cylindrical piston, positioning a core-supporting member on said flask, suspending a core from said member coaxial with said print, holding said core to prevent displacement thereof, and then pouring aid mold. a

8. A method of casting pistons, which compises forming in a flask a sand mold having a cylindrical print fof the external form of a complete cylindrical piston, positioning on said flash a core-supporting member having an aperture therethrough coaxial with said print, suspending a core through said aperture into said print, holding said core to prevent displacement thereof, and then pouring said mold.

9. A met 10d of casting pistons, which comprises forming in a flask a sand mold having a cylindrical print for the external form of a complete cylindrical piston, fixing on said flask against horizontal movement a coresupporting member having an aperture therethrough coaxial with saidprint, suspending a core from said member through said aperture into said print, weighting said core to prevent displacement thereof, and then pouring the mold. r

10. .A. molding apparatusfor casting pistons, comprising a flask body having a substantially vertical surrounding side wall, guide means positioned oppositely and projecting from the external top portion of said side wall, said flask bodycontaining molding sand having a cylindrical mold print formed therein, a plate member supported by and on said side wall and having a circular aperture therethrough of a diameter greater than the diameter of said print, said plate member being recessed about said aperture to provide an upward facing annular shoulder, means on said plate member c'ooperable with said guice means to position said plate member on said body with said aperture concentrically over said print, a sand core member in said aperture and removably supported by said plate member, said core member having a circumferential flange of a diameter substantially equal to the diameter of said aperture whereby said flange closes the top end of the annular metal receiving space and having a flange above and extending laterally from said first-named flange, said second-named flange cooperating with said upwardly facing shoulder to support said core member.

11. A molding apparatus for casting pistons, comprising a flask body having a substantially vertical surrounding side wall, guide means positioned oppositely and projecting from the external top portion of said side wall, said flask body containing molding sand having a cylindrical mold print formed therein, a plate member supported by and on said side wall and having a circular aperture therethrough of a diameter greater than the diameter of said print, said plate member being recessed about said aperture to provide an upward facing annular shoulder, means on said plate member cooperable with said guide means to position said plate member on said body with said aperture concentrically over said print, a sand core member in said aperture and removably supported by said plate member, said core member having a circumferential flange of a diameter substantially equal to the diameter of said aperture whereby said flange closes the top end of the annular metal receiving space and having a flange acting by force of gravity to hold said sec-,

end-named flange against said shoulder.

In testimony whereof I have hereunto signed my name.

i DANIEL H. MELOCHE.

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