US2386028A - Centrifugal pot casting - Google Patents

Description

Oct. 2, 1945. Y E. c. YOUNG CENTRIFUGAL POT CASTING Filed July s, 1944 f X.

2 Sheets-Sheet 2 HHHHII H Xnue 'for y Edwn @Youn Patented Oct. 2, 1945 CENTRIFUGAL POT CASTING Edwin .0. Young, Muskegon, Mich., assignor to Sealed Power Corporation, Muskegon, Mich., a

corporation of Michigan Application July 3, 1944, serial No. 543,307

(c1. :a2-ss) 5 Claims.

This invention relates to centrifugal casting and is more specifically concerned with a mold for centrifugally casting sleeves or pots, as they are called, which after casting may be cut transversely to provide individual piston ring blanks, from each of which a piston ring ls made.

Finished piston rings are parted at one side and normally are open at said parting vgreater or less distances, in accordance with the tension which the ring is to have when closed at the parting. When the ring is closed at the parting it takes circular forms at its outer and inner curved surfaces, as nearly perfect as it can be machined so as to bear against the inner walls of an nternal combustion engine cylinder with equal pressure throughout its length. The initial casting for piston rings includes the finished castthat 'they may be sawed to make generally two or more individual ring blanks have been cast in such out of round form, by still or static molding, that is, the pouring of molten metal into a stationary mold having the out of round shape cavities for receiving the metal.

With my invention a sleeve or pot is centrifugally cast in the desired out of round form and with walls of the same thickness or radial dimension. And it is a primary object and purpose of the present invention to provide a very practical, economical and certain mold construction, by means of which such centrifugal sleeve or pot casting may be expeditiously performed and perrect sleeves or pots obtained which may be cut transversely to provide a large number of individual ring blanks, each of which may be machined in accordance with accepted practice to obtain a piston ring for usefin internal combustion engines, or at other places of use where rings or packing of this character are desirable. The piston ring thus produced has its metal of a substantially luniform homogeneous character throughout the body thereof.

An understanding of the invention may be had from the following description vtaken in connection with the accompanying drawings, in which,

Fig. 1 is a central vertical section through a mold in accordance with my invention and showing the mold at theend of a casting operation therein, the section being substantially on the plane of line I--I of Figni. l

` Fig. 2 is a horizontal section on the plane of line 2--2 of Fig. 1.`

Fig; 3 is a central vertical section illustrating the flask and pattern used therewith,and the manner in which it is used for providing the outer green sand mold, and

Fig. 41s a plan view 'of the mold shown in Fig. 1. Like reference characters refer to like parts in the different iigures of the drawings.

, The ask l whichmay-,jbe of cylindrical form and of metal has a green sand mold 2 therewithin which preferably is obtained by inverting the flask, as in Fig. 3 and, placing it upon a bed plate 3 having a central openingand an exterior circular rim 4 within which the inverted edges of the flask l are received. A pattern 6 is provided 'and mountedv on and extends above a movable stripper plate Sthrough the opening in the bed plate, the upper end of which pattern has a cylindrical projection 1 with tapered sides as shown of reduced diameter. At-the upper side of the bed plate 3 ,a frustro-conical member 8 as shown is secured by screws 9 through which the pattern 6 passes. Extending to one side from the member 8 is a bar lll which extends to and through a notch to receive it in the lower end and at one side of the flask. The sand mold 2 is formed in the usual manner under proper tampering, ramming or squeezing, or in any of the ways in which the mold is made of theproper density, filling the space between the pattern and the ask and having an annular inwardly'extending ledge Il around the upper projection l on the pattern as shown, with an opening l 2 with l inclined sides left where the projection l was located. The pattern and plate 5 may be moved downwardly relative to the bed plate, flask and mold to strip the pattern from the mold and then the ask and mold removed from the plate 3 and the member 8 leaving-the green sand mold 2 surrounding the central recess therein.

It is to be understood that the section 6 of of the patternv between the projection l and the stripper plate 5 is of anoutside shape corresponding to the outside out of round curvature desired in a piston ring casting. That is, thesection 6 is not of a cylindrical form but is of theout oi round Shape and form likethat of a circular pattern which has had a parting made at `one side and a desired length of segment inserted therein. The flask l and the moldv 2 therein, inverted after the mold has been formed, at their .upperl ends will have a slot I3 in the flask at one side (Fig. 1) in which the pattern portion I was seated at its end in molding, and the mold 2 will have a slot I4 in alinement therewith.

The flask and mold are placed upon the upper side of the table I5 which is mounted for rotation about its verticalaxis for centrifugal casting, the lower end portions of the flask when inverted being received within'a surrounding rim I5a at the upper side of the table I5 as shown in Fig. 1. At the inner side of and at the lower portions of the rim I5a an annular groove I6 is cut extending downwardly and outwardly, from which radial passages IGa are made through to the outer side of the rim for the ready outward centrifugal expulsion of any loose sand which may be present at the upper side of the recessed portion of the table. In addition centrally of the table a cylindrical downwardly extending recess I1, the walls of which at the upper end portions are inclined outwardly and upwardly in conical form, is made from which lateral passages |8 extend for the same purpose of centrifugally throwing sand outward which may be in the recess Il. Also at its sidesl the table I5 is provided with vertical slots I9, the purpose of which will be later described.

Within the mold 2 a baked sand core 20 is positioned having a frustro-conical downwardly extending projection 2I which passes through the opening I2 in the mold and seats in the recess at I'I. At its upper end the core is formed with an annular flange 22 shaped to be received in the mold 2 at the frustro-conical recess provided therein by the member 8 previously described. 'I'he intermediate portion of the core 20 likewise is not of a circular form, but is of an out of round form corresponding to the out of round shape of the inner walls of the-mold 2 so that when properly located, the outer sides of the intermediate portion of the core are spaced equallydistant from the inner walls of the sand mold 2.

In order that such proper positioning shall occur positioned, being received-in a recess made therein around the upper end of the cylindrical centra] opening 24, the core being provided with an opening 26 preferably having inclined sides, the lower end of the opening 26 being'of less diameter than the diameter of the opening 24.

With the core as thus described, properly positioned and located within the mold, a plate 2'Iv of metal is placed over the upper ends of the flask, the mold 2 andthe upper flanged portion 22 of the core 20, said plate having a central opening 28 through which the core at 25 extends, as shown. The plate 21 at its outer portions is provided with a downwardly extending ring 23 `which passes around the upper end portions of the flask I, and saidring 23 is provided at its edge portions with vertical slots 30. *Headed bolts 3I are located in the slots 30 and I9 and nuts threaded into opposite ends of the bolts are tightened thereby clamping all of the parts .in

lsecured and rm relation to each other.

aaeaoaa l of said core 20 as shown in Fig. 1. The table I5 being rotated at the requisite speed of rotation, the molten metal is forced outwardly by centrifugal action through said passages and fllls the mold cavity to its upper end proyiding the sleeve or pot 32 from which narrow radialsections 33 extend inwardly through the passages in the core which have been mentioned, and the inner cylindrical opening 24 retains any excess of molten metal over that required to flll the mold cavities and may extend from the bottom of the opening 24 to the shoulder at the under side of the entrance or pouring core 25 as shown at 34. At the vouter ends of the passages through which the molten metal passes to the mold cavity a thickened rib 35 may be provided, by a proper vertical longitudinal groove in the side of the core section 20 to serve as a marker on each individual ring casting or blank made by cutting or sawing the sleeve transversely, it being at such marker portion of the individual ring casting or blank that the parting segment is removed in the process of finishing the piston ring.

With this invention a mold having a proper greenI molding sand body is provided, associated with which ls an interiorly positioned baked sand core, and with each of the molds as thus provided a centrifugal cast out of round pot or sleeve is expeditiously made. The transverse sawing or cutting of the sleeve or pot will produce from each sleeve a large number of piston ring blanks, each of which may be finished to make a cast piston ring. The green sand mold is rammed toits proper density and the quality and consistency of the green sand used is the same as has been used in previous still or static ring casting molds. The .product obtained is one in which the metal is substantially homogeneous throughout, without variations in composition or in physical properties so that a uniformity of product is obtained in a practical economical manner. l

Variations in detail of the mold structure may be resorted to without departing from the invention. For example, the upper projecting flange 22 of the ycore may extendto and seat against the flask I instead of the green sand mold 2, the inner side ofthe flask at its upper end being shaped to conformlto the edges of the part 22. Also the core 25 may be made integral with the core 20 and not separate, without change in operation or function. Furthermore, instead of separated ports for the flow of the molten metal from the central recess 24 tothe mold cavity between the core and the green sand mold a single lport extending from the bottom of the central cavity 24 to or nearly to the upper end of the mold cavity may be provided. Likewise while preferably the mold at 2 will be of green sand and the core of baked sand,y different materials than these canv be used, as for example, in providing a permanent mold, using the materials which are normally used in permanent molds. All of these variations in detail are within the invention which is not avoided by such changes.

The invention is defined in the appended claims and is to be considered comprehensive of all forms `of structure coming within their Seppe. I claim:

1. In centrifugal casting. a table adapted to be turned about a vertical axis, said table having a flask receiving recess at its upper side, a flask having its lower end received in said recess, a mold within said ask extending to the upper L`\e\nd thereof, said mold havingv a generally H `the inner sides of the mold to provide an elongated sleeve-like recess, the upper end of the mold having an enlarged opening'and the upper end of the core being enlarged to t therein, said enlargedupper end of the core closing the upper end of said mold cavity, and said core having a central opening extending from its upper end downwardly therein to adjacent the lower end of said mold cavity with passage means for the fiow of molten metal from said central opening to the cavity, as specified.

2. A construction as dened in claim 1, said mold cavity in horizontal cross section being of an out of round form like the outer of round shape of a piston ring casting, and the upper end of said mold and of said core having locating means thereon for properly locating the core` and mold relative to each other to space the core at its sides thereof equal distances from the inner sides of the mold.

3. A construction as defined in claim 1, said core a1; its upper end having'a second core with an opening therethrough for the pouring thereinto of molten metal, said second core being seated in the upper end portion of the first named core, and the opening through the second core at its lower end being of less cross sectional area than that of the downwardly extending opening 5 in the rst core.

4. A construction as dened in claim 1, a plate located over the upper ends of said nask, mold and core, andmeans for releasably securing the plate in position thereover, said plate having a central opening whereby molten iron may be poured into the central opening downwardly in said core. i

52 In centrifugal casting a table adapted to be turned about a vertical axis, said table having a ilask receiving recess at its upper side, a Ilask having its lower end received in said recess, Aa mold within the flask extending to the upper end thereof, said mold having a generally central larger vertical opening from its upper end and nearly to its lowe'r end and a smaller central 'ropening extending therefrom to the lower end of the mold, said larger vertical opening at its upper port1on having an annular enlargement, a core inserted lengthwise of said opening having a4 5 projection at its lower end passing through the smaller opening in the lower end of the mold, said table at its upper side having a central recess receiving the lower end of said core, and said core at its upper end having a ange extending therefrom received in the annular enlargement of the upper end of said opening, said core between said ange and projection being spaced from theinner sides of the mold to provide an elongated sleeve-like cavity said core having a central opening extending from its upper end downwardly to adjacent the lower end of said mold cavity with passage means for the flow of molten metal from said central opening to the cavity, a plate located over the upper ends of the ask, mold and core and bearing thereagainst, and means detachably connecting said plate to the table.

EDWIN C. YOUNG.

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