US2745152A

US2745152A - Centrifugal metal casting process and mold apparatus

Info

Publication number: US2745152A
Application number: US441022A
Authority: US
Inventors: Clarence K Johnson
Original assignee: Electric Steel Foundry Co
Current assignee: Electric Steel Foundry Co
Priority date: 1954-07-02
Filing date: 1954-07-02
Publication date: 1956-05-15
Anticipated expiration: 1973-05-15

Description

May 15 l956 c. K. JOHNSON CENTRIFUGAL METAL CASTING PROCESS AND MOLD APPARATUS Filed July 2, 1954 CENT RIFUGAL METAL CASTING PROCESSv AND MOLD APPARATUS Clarence K. Johnson, Portland, Greg., assigner, by mesne assignments, to Electric Steel Foundry Company, Portland, Oreg., a corporation of regon Applicatie July z, 1ss4, serial No. 441,022

14 Claims. (ci. 22u65) This invention relates to a centrifugal metal casting process and mold apparatus. The invention is particularly useful in the casting of a large number of individual castings within a single annular mold, but has' other applications.

One of the basic problems in centrifugal casting of metal has been to control the metal as it is poured into the mold so as to prevent the metal from rushing through the length of the mold in an irregular fashion producing laps, metal inclusions, cold shuts, etc. Various methods have been suggested as a means for retarding the ilow of metal and otherwise preventing such undesired results, but such methods have not solved the problem.

An object of the present invention is to provide a method and means for restraining the ow of metal until certain desired conditions have been reached, and then releasing the metal in a form in which an even distribution on the inside diameter of the casting is obtained so as to cast an uneven contour on the inside diameter of the casting. Another object is to provideV assembled cores in combination with a control core whereby the llow of metal is retarded and a uniform casting of a contour on the inside diameter is obtained. Yet another object is to provide a combination of cores arranged in such a manner as to control the flow of metal along the inside diameter of the cores while at the same time lling radial recesses within the cores, the feed being in the form of an annular stream which progresses substantially and uniformly Within the cores, thus avoiding the formation of laps, metal inclusions, cold shuts, etc. A further object is to provide a control core in which the passages are provided with an angle to give a pump effect, thereby increasing the eciency of the operaton. A still further object is to provide the initial mold ring, which receives the inrush of metal of abrasion-resisting material, whereby erosion at this point will be avoided. objects and advantages will appear as the specification proceeds. l

The invention is shown, in an illustrative embodiment, by the accompanying drawing, in which- Figure l is a broken, longitudinal sectional view showing the arrangement of cores within the mold embodying my invention, while also illustrating the process of my invention; Fig. 2, a side view in elevation of the united castings formed in the process, Fig. 3, a front View in elevation of a casting produced in the process; Fig. 4, a front face View in elevation of the control core which may be employed; and Fig. 5, a sectional View, the section being taken as indicated at line 5-5 of Fig. 4.

In the illustration given, designates a metal mold having bearing portions or tires 11 supported by the usual wheel bearings 12. The outer end of the mold 10 is provided with a flared mouth portion 13 adapted yto receive a closure plate 14 apertured centrally at 15, the

plate being adapted to be secured in position by wedges 16. Since the foregoing is Well known structure, a detailed description herein is believed unnecessary. It

Other specific ICC will be understood that any type of centrifugal mold apparatus may be employed in the practice of the present invention.

Within the flared portion 13 of the mold, I secure an end core 17 provided with a central opening aligned with the opening 15 of the closure plate and abutting an elongated annular core 18. At the other end of the annular core 18, I provide a control core 19. If desired, any or all of the `cores may be provided with interlocking ribs and grooves. The core 19 is provided with a series of spaced openings 21, which may be of any designed number and of any size diameter. By way of example, in the mold shown, the core 19 is one inch thick and there are six openings 21 of one-half inch diameter. It will be understood that any number of. peripheral openings 21 may be employed for controlling the ow of metal inwardly into the mold along the inner periphery of the cores therein.

Inwardly of theY control core 19 are a plurality of molding cores 22. VEach of the cores 22 is supported within a metal ring 24, as shown more clearly in Fig. l, and is provided with a radial recess 25. In the speciiic illustration given, the recess 25 has a radial portion, in-

dicated by the numeral 26, and a horizontal portion, in-

dicated by the numeral 27. 1

The usual pouring cup 28, formed of molding sand,

or thel like, is supported in position for introducing molten central opening 23 which serves to release gases that are generated by the combustion'of the core sands. Further, l prefer to form the first ring 20 adjacent the control core 19 with means for resisting abrasion caused by the initial surge of eroding metal. The first ring 20 is preferably made of extra hard core sand which is able to receive the initial surge of eroding metal without It will be erosion by the inrush of this initial metal. understood that any suitable means vfor increasing the abrasion resistance of the lirst ring 20 may be employed.

The passages or openings 21 through the control core' 19 may be horizontal or of any desired contour. I prefer, however, to angle the holes so' as to give a pump effect and thus cause metal to be sucked through the holes instead of relying on mere horizontal flow. As shown more clearly in Figs. 4 and 5, the holes or passages have been given an angle of about twenty degrees, which is found to give an effective pumpetlect. I have employed an angle away -from the horizontal of from zero to fortyiive degrees with excellent results.

V'lhe core layout as set out in the drawings is effective in filling uniformly one cavity at a time and thus keeping the metal from dancing over to the next core and then later iilling up, thus forming laps and cold, shuts, but a primary and important object and result is to contour Vthe internal diameter of the rings with their radial and horizontal recesses.

The molding cores may. ofcourse, be of any desired shape or yform so as to produce rings or other castings which are preferably united by riser metal which may be removed later by machining or other means. In Fig. 2, a stick of castings is shown in the form that they are produced by the molding core structure shown in Fig. l, the outer ring structure being indicated by the numeral 30, the inner annular flange being indicated by the numeral 31, and the riser metal connecting the rings being shown by the numeral 32. In the specific form illustrated, I cast lugs 33 upon the inner structure of the ring. The show ing, however, is for the purpose of illustration, and it will be understood that any molding cores providing the desii-ed radial recesses for reception of the metal may be employed.

Operario/t In the operation of the process and structure shown, molten metal 29 is poured into the cup 28, which is supported upon a stationary support (not shown) for discharging metal into the rotating mold lll. The mold it? is rotated by mechanism (not shown) in the usual manner to attain a rotational speed causing the metal as it enters to form an annular reservoir 34 within the chamber formed between the control core 19 and the inlet core 17. The control core E9 thus restrains longitudinal flow of the metal 29 until the depth of the annular reservoir 34 covers the openings 2l. The metal then flows through the openings 21, which are preferably angled and distributed at spaced distances along the peripheral por tion of core 19 within the reservoir chamber, and advances along the interior of the cores 22. The pumping action of the control core increases the eliiciency of the operation and brings about an even, steady ilow of metal along the internal diameter of the cores. The radial recesses within the cores 22 are filled individually as the metal progresses and exert a retarding and regulating influence upon the flow of the metal. As a result, it is found that a uniform contour is cast on the inside diameter of the castings, without metal inclusions, cold shuts, laps, etc.

In Fig. l, the progress of the metal during the pouring operation is illustrated, a rather uniform reservoir of uniform thickness being maintained in the reservoir chamber between cores 17 and 19. A thin annular stream of metal Hows past the control core 19 and longitudinally of the composite cores 22, the radial recesses 25 serving to retard and control the flow of the metal past the various cores 22. In this manner, it is found that an inside diameter contour is formed on the castings and the riser metal between the ring castings may later be cut away to form the separate rings.

In the foregoing operation, it will be noted that l require four cores, namely, the inlet core i7 having a central opening for receiving the metal from the cup 23, a sleeve or annular core 1S forming a reservoir, the control core 19, and the abrasion core 2d. The openings 21 in the control core i9 may be circular, rectangular, elliptical, or of any suitable or desired shape.

In the foregoing operation, the provision of the reservoir at one end of the mold cavity, in combination with the peripheral openings 2l in the control core E9, allows the metal, which has gained the same peripheral speed as that of the mold, to proceed evenly through the full length of the cavity, the radial recesses of the individual molding cores 22 providing spaced retarding means controlling the flow of the metal. Also, the structure serves to keep the metal from skipping partially to the next core and then filling up later, thus causing laps and cold shuts.

After the casting has been formed, the wedges 16 may be removed and the endplate .ld and cores 17, I8 and 19 removed. A long metal bar may be passed through the castings and drawn outwardly to remove the stick of castings illustrated in Fig. 2. ln this operation, the cores 22 are usually disintegrated and the spaced outer` rings 24, which aid in the breaking up on the cores 22, may be removed. The connecting riser metal 32 may then be severed, as already stated, to free the separate ring castings or other types of castings which are formed in the process.

While in the foregoing specification l have set forth in considerable detail a specific process and core arrangement for the purpose of illustrating my invention, it will be understood that such details may be varied widely by those skilled in the art without departing from the spirit of my invention.

I claim:

l. ln a centrifugal casting process for forming a casting in a mold, in which process molten metal is poured into a mold mounted for rotation and the mold rotated about an axis to form a casting, the steps of mounting within said mold an annular core having radial recesses therein, pouring the molten metal into one end of the mold, restraining the longitudinal ow of the metal in said end of the mold until the metal has attained the peripheral speed of the mold, and then releasing the metal in a thin annular stream along the inside diameter of the core.

2. In a centrifugal casting process in which molten metal is poured into a mold mounted for rotation and the mold rotated about an axis to form the casting, the steps of introducing a plurality of annular cores into the mold to form radial recesses, pouring the molten metal into one end of the mold while rotating the mold, substantially restraining the llow of the metal in said end of the mold until the metal has attained the peripheral speed of the mold, and then releasing the metal in a thin annular stream along the inside diameter of said cores.

3. The process of claim 2, in which the metal is released through spaced passages inclined from the horizontal.

4. The process of claim 2, in which said radial recesses have grooves in communication with said radial recesses.

5. The process of claim 2, in which the molten metal is fed at spaced intervals along the inside diameter of said cores.

6. In combination with a centrifugal mold mounted for rotation and having a central inlet opening at one end and means for introducing molten metal into said opening while the mold is operating, a core mounted within said mold and having -a radial recess therein, and a control core adjacent said molding core and spaced from the inlet of said mold to provide a reservoir, said control core having a plurality of openings aligned generally with the inside diameter of said core.

7. The structure of claim 6, in which said openings in the control core are spaced slightly inwardly of the inside diameter of said core.

8. In combination with a centrifugal mold mounted for rotation and having a control opening in one end and means for introducing molten metal into said opening while the mold is rotating, a plurality of mold cores supported within said mold and providing spaced radial recesses, and a control core adjacent said molding cores and spaced from the inlet of said mold to provide a reservoir, said control core having peripheral passages therethrough generally aligned with the inside diameter of the cores.

9. The structure of claim 8, in which the peripheral passages of the control core are inclined from the horizontal within a range of between zero and 45.

l0. The structure of claim 8, in which the peripheral passages of the control core are inclined from the horizontal by about 20.

1l. In combination with a centrifugal mold mounted for rotation and having a closure plate at one end provided with a central opening and means for introducing molten metal into said opening, an inlet core having an opening aligned with the opening in said closure plate, a sleeve core received within said mold and engaging at one end said inlet core, a control core engaging the other end of said sleeve core, and a mold core on the opposite side of said control core and having radial recesses, said control core having a plurality of spaced openings generally aligned with the inside diameter of said mold core.

l2. In combination with a centrifugal mold mounted for rotation and having a closure plate at one end provided with a central inlet opening and means for introducing molten metal into said opening while the mold is rotating, an inlet core secured across the end of said mold by said closure plate, a sleeve core within said mold and abutting said inlet core, a control core abutting the other end of said sleeve core, said control core having spaced annular openings therethrough, a plurality of mold cores having radial recesses therein, and rings within said mold and separately supporting said mold cores.

13. Mold apparatus, comprising a centrifugal mold mounted for rotation and having at least at each end a closure plate and inlet core, each provided with an inlet opening for receiving molten metal While the mold is rotating, a sleeve core within said mold and abutting said inlet mold, a control core abutting the other end of said sleeve core, said control core having spaced annular openings therethrough and having also a central opening, a plurality of mold cores having radial recesses therein, and rings within said mold and separately supporting said mold cores.

14. Mold apparatus, comprising a centrifugal mold mounted for rotation and having at least at each end a closure plate and inlet core, each provided with an inlet opening for receiving molten metal while the mold is rotating, a sleeve core within said mold and abutting said inlet mold, a control core abutting the other end of said sleeve core, said control core having spaced annular openings therethrough, and a plurality of mold cores having radial recesses therein, one of said mold cores abutting said control core being formed of erosion-proof material.

Wolf Aug. l5, 1922 Lohmann Dec. 11, 1923

Claims

1. IN A CENTRIFUGAL CASTING PROCESS FORMING A CASTING A MOLD, IN WHICH PROCESS MOLTEN METAL IS POURED INTO A MOLD MOUNTED FOR ROTATION AND THE MOLD ROTATED ABOUT AN AXIS TO FORM A CASTING, THE STEPS OF MOUNTING WITHIN SAID MOLD AN ANNULAR CORE HAVING RADIAL RECESSES THEREIN, POURING THE MOLTEN METAL INTO ONE END OF THE MOLD, RESTRAINING, THE LONGITUDINAL FLOW OF THE METAL IN SAID END OF THE MOLD UNTIL THE METAL HAS ATTAINED THE PERIPHERAL SPEED OF THE MOLD, AND THEN RELEASING THE METAL IN A THIN ANNULAR STREAM ALONG THE INSIDE DIAMETER OF THE CORE.

6. IN COMBINATION WITH A CENTRIFUGAL MOLD MOUNTED FOR ROTATION AND HAVING A CENTRAL OPENING AT ONE END AND MEANS FOR INTRODUCING MOLTEN METAL INTO SAID OPENING WHILE THE MOLD IS OPERATING, A CORE MOUNTED WITHIN SAID MOLD AND HAVING A RADIAL RECESS THEREIN, AND A CONTROL CORE ADJACENT SAID MOLDING CORE AND SPACED FROM THE INLET OF SAID MOLD TO PROVIDE A RESERVOIR, SAID CONTROL CORE HAVING A PLURALITY OF OPENINGS ALIGNED GENERALLY WITH THE INSIDE DIAMETER OF SAID CORE.