US2073199A - Centrifugal casting - Google Patents

Description

Mam-c119, 1937. M DU AS 2,073,199

CENTRIFUGAL CASTING Filed Dec. 19, 1933- 4 Sheets-Sheet 1 INVENTOR March 9, 1937.

M. G. DUMAS CENTRIFUGAL CASTING 4 Sheets-Sheet 2 Filed Dec. 19, 1933 INVENTOR March 9, 1937. M. G. DUMAS CENTRIFUGAL CASTING Filed Dec. 19, 1953 4' Sheets-Sheet 3 INVENTOR Ma mw March 9, 1937. M DUMAS 2,073,199

CENTRIFUGAL CASTIN G Filed Dec. 19, 1933 4 Sheets-Sheet 4 Patented Mar. 9, 1937 UNITED STATES CENTRIFUGAL CASTING Maxwell G. Dumas, Pittsburgh, Pa., assignor to The Dumas Engineering Company, Youngstown, Ohio, a corporation of Ohio Application December 19, 1933, Serial No. 703,086

4 Claims.

This invention relates to new and useful improvements in centrifugal casting, more particularly to the centrifugal casting of ingots, bars, slabs and the like, and it is among the objects thereof to provide a method of casting a plurality of ingots or bars by feeding the metal simultaneously at both ends of the ingot bars or slabs.

Another object of the invention is the provision of apparatus whereby molten metal may be fed to a double ended mold from a common source to separate flow spouts while regulating the rate of flow in the separate spouts to prevent piping, such apparatus embodying themultiple pouring device of my Patents Nos. 1,915,650 and 1,915,651 granted June 27, 1933.

A further object of the invention is the provision of a mold structure designed to form a multiple of ingots or bars integrally in the form of a squirrel-cage to maintain the cast bars in proper spaced relation to prevent their collapse in the mold after the speed of the mold has been reduced, and to facilitate the removal of the casting from the mold;

Another object of the invention is the provision of a mold structure for casting ingots or bars by centrifugal force which shall provide a fourwalled form in which the bars are cast, and which shall simultaneously provide means for controlling the thermal condition of the metal during the centrifugal casting operation.

Still a further object of the invention is the provision of means for centrifugally casting shapes such as squares, rounds and other structural shapes.

These and other objects of the invention will become more apparent from a consideration of the accompanying drawings constituting a part hereof in which like reference characters designate like parts and in which Figure 1 is a top plan view of a pouring device showing a mold for centrifugal casting in sections; Figure 2 an end elevational view of the pouring device and crosssection of the mold taken at right angles to its axis of rotation; Figure 3, a cross-sectional view of a fragmentary portion of the end of the mold taken parallel to the mold axis; Figure 4 an en-' larged detail showingacross-sectionofthecastbar or ingot; Figure 5 a top plan view of a pouring device and centrifugal casting mold, the latter being in longitudinal section and embodying a refractory liner; Figure 6 an end elevational view thereof with the centrifugal casting mold in vertical section; Figure 7 a front elevational view partially in section of a modified form of centrifugal casting device with the mold axes vertically disposed; Figure 8 a. transverse cross-sectional view of the mold; Figure 9 a cover member for the mold; Figure 10 a fragmentary portion in side elevation of the top of the centrifugal mold; Figure 11 a top plan view partially in section of a 5 modified form of mold; Figure 12 a cross-sectional view of a mold for centrifugally casting hexagonal bars; and Figure 13 a cross-sectional view of a mold for centrifugally casting round bars.

My method of centrifugally casting ingots is 10 practiced by the employment of a split mold I which consists of two or more sections joined at the center line 2 and retained by a. cylindrical housing 3, Figures 1 and 3, to render it separable I for the removal of the casting therefrom, the 15 mold housing 3 being supported on rollers 4, Figure 2, which are driven by a motor 5 through a suitable drive mechanism 6 to subject the mold to rotary motion.

The particular mounting or drive mechanism of the mold is available in the art and constitutes no part of the present invention.

The inner wall of the mold is provided with flutes or slots 1 in angularly spaced relation, the slots being the forms or matrices of the mold in 25 which the ingots or bars are cast.

As shown in Figure 1 of the drawings, the slots 1 terminate into annular recesses 8 at their respective ends, the recesses being provided with radial flanges or gates 9 which are adapted to retain the metal against escape from the mold. The annular grooves 8 adjacent the ends of the matrices l are of shallow depth as compared with the matrix grooves l and are chamfered or flared at 8a to feed the metal into the grooves from both ends so as to assure a sound homogeneous casting throughout the length of the ingot or bar.

The metal is fed to the annular chamber 8 by spouts Ill which project into the groove 8 and communicate at their upper ends with lips I I of a. pouring receptacle l2, the receptacle being mounted upon journals l3, Figure 2, to render it tiltable, thereby controlling the flow of the metal.

The pouring receptacle l2 may be provided with a cover M which is suitably insulated by a refractory material to maintain the molten metal therein at proper pouring temperature during the casting operation. The receptacle l2 may be adjustable horizontally to control the relative flow of metal from the lip ll thereby obtaining suitable regulation to obtain equal volumes of flow to the respective spouts so that an equal amount of metal will be fed to the grooves of the mold from both ends simultaneously to eliminate discontinuity.

As shown in Figure 2, the pouring receptacle I2 is mounted on a suitable frame or support I! to provide the proper elevation for the gravity flow of the metal from the receptacle to the 5 spouts into the annular end compartment 8 of the mold.

The operation of the above described, apparatus and the method of pouring ingots, bars, slabs, etc., accomplished thereby is briefly as foll lows:

With the two half-sections of the split mold mounted in the housing 3 and with the housing supported on the drive rollers 4, the motor is energized to actuate the mold causing it to rotate about its central axis, the speed of rotation being sufficient to produce the necessary pressure on the metal by centrifugal action to form a sound and homogeneous casting. When the mold has been brought up to the proper speed of rotation, the pouring receptacle I! which has been charged with molten metal is tilted about its journals l3 until metal begins to pour from the lip I I into the large portion of the spout ID from which it is conducted into the annular end 2 chambers 8.

As the end chambers are more shallow than the grooves l, the metal will be subjected to the motion of the mold and then will flow downwardly along the chamfered faces 8a into the grooves 1. As the metal poured into the mold is subjected to the same speed as the speed of the mold when fiowing into the annular end chambers 8, it will readily flow into the grooves 1 without striking the projecting portions of the mold between adjacent grooves thus assuring a smooth flow towards the center of the grooves.

In conventional types of centrifugal casting apparatus, it has been difficult to form sound ingots due to the fact that metal was customarily fed from oneend of the mold only, this difilculty being overcome in the instant case by feeding the metal from both ends of the grooves towards the center. spouts in may be regulated by tilting the receptacle l2 more or less" to thereby control the density of the cast ingots or slabs and eliminate piping. When the mold grooves I- and the annular end grooves 8 have been filled to a proper depth with metal, the pouring receptacle I 2 is tilted to the position where the metal will cease to flow from the lip II and after the metal in the mold has sufilciently set, the motor! is deenergized and the cast structure is removed from the mold by first removing the housing 3 and then splitting the mold sections. Another method of controlling the amount of the metal for each casting is to limit the capacity of the pouring receptacle so that it must be completely emptied to supply the proper amount of metal to the molds.

The resultant structure is of squirrel-cage form having horizontal bars in annularly spaced relation with end rings integrally formed with the bars, these and rings being subsequently broken-off or cut from the bars and themselves formed into bars or ingots by splitting them and straightening them in any suitable manner.

It will be seen from the foregoing description of this invention thatby the provision of the end chambers cooperating with the axially disposed matrix grooves, the metal will be given the proper direction of fiow and the grooves will 75 grooves resulting in unsound ingots or bars,

The rate of flow from the Also. by utilizing the pouring receptacle with the spouts on both ends of the mold, the metal fed to the mold can be regulated in any desired manner. One of the difllculties encountered in the forming of ingots or bars by centrifugal casting is due to the porosity of the inner surface of the bars which is equivalent to the piping formed in the casting of large ingots which necessitates the employment of hot tops or sink heads for feeding metal to the center of the ingots as the metal sets. Similarly, it has been found that in centrifugal casting of bars, the matrix surfaces with which the metal contacts produce a rapid chilling effect on the three sides of the bar leaving the non-contacting inner surface with pipes or ruptures.

To overcome this difficulty, a refractory liner is employed as shown in Figures 5 and 6 of the drawings and which consists of the following:

A cylinder I 6 of refractory material such as clay is disposed centrally within the split mold sections 2, its end terminating in the annular grooves at the end of the molds so that the longitudinal slots 1 are closed on all four sides excepting at their ends where they communicate with the annular grooves 8.

When the metal is fed from the spout ID of the multiple casting member l2, it will flow in the annular grooves 8 and then from the grooves through the respective ends of grooves towards the center of the mold, the metal being in contact with the three sides of the groove 1 and the outer wall surface of the cylinder l6. 'I'hemetal fills the grooves and displaces the air, while in molds where the liner I6 is not employed the metal will oxidize rapidly due to its contact with excess hot air under pressure caused by the rapid rotation of the mold. The cylinder l6 may be preheated if desired in any suitable manner although this can be dispensed with if desired as the refractory substance of the cylinder I8 will prevent excessive chilling of the inner surface of the cast bars so that the metal will feed towards the .center of the bars or ingots in the same manner as the metal blowing from a sink head or hot top in the stationary pouring method.

When the bars have been cast in the manner heretofore described, the outer shell 3 of the mold is removed and the split mold section dropped off leaving the cast bars integrally joined with the annular rings 8 and when these rings are knocked oil at their thin sections at the chamfered portion 8 of the bars, the bars will be removed from the refractory cylinder IS without even recessitating the breakage of the cylinder.

In Figures '7 to 10 inclusive of the drawings, I have shown a modification of the centrifugal casting device of Figures 1 to 6 inclusive in which the mold generally designated\by the numeral "is a conical shell l8 provided with bosses I 8 by means of which it is securedto a tum table 20 by the wedges 2|. I

The upper portion of the shell I8 is provided with a track 22 for engaging rollers 28 of a pair of hinge arms. 24 that are pivoted to the base 25' thereof in the manner shown in Figure 8 to isolate the slots 28.

A clamping ring is placed on the top of the mold and shell l1 and I8, and is secured to lugs 3! by wedges 32.

The turn table 20 is actuated through a bevel gear drive 33 and a prime mover designated at 34.

A pouring receptacle I! with spouts I0 is provided and is preferably mounted on trunnions to be tiltable, and'the trunnion members in turn may be mounted on a. track so that the pouring receptacle may be employed to serve a plurality of centrifugal molds arranged in groups with two of such molds in alinement so that two sets of castings can be poured simultaneously.

The metal is cast through spouts l0 into an annular space 36 provided at the top of the mold from which the metal feeds downwardly into the troughs 28 between the refractory center 29 until the slots or grooves 28 are filled to the top and the formation of piping in the bars is prevented by'the refractory center 29 in the same manner as explained in connection with the liner of Figures 5 and 6 of the drawings.

When the castings are completed, the arms 24 are swung back and the shell or housing It is removed permitting the liner and bars to be stripped from the mold.

In the structure shown in Figure 11 the mold is bellied to accelerate the flow of the metal from the annular chambers at the respective ends to the center. The construction is identical with that of Figure 5 excepting that both the matrix or grooves 'l of the mold and the liner I are of bellied shape.

In Figure 12 the mold I and liner l6 each constitute matrix portions and 40a for casting hexagonal bars and, Figure 13, round bars. When the liner i6 is grooved to constitute such matrix portions it is necessarily of heavier wall sections than if the liner is employed as a straight side as in Figures 5 and 6.

Although one embodiment of the invention has tee herein illustrated and described, it will be obvious to those skilled in the art that various modifications may be made in the details of construction without departing from the principles herein set forth.

.inner wall of said mold, a liner complementary in shape to the inner wall of the mold and in contact with said wall, and means at the respective 'ends of the mold for simultaneously feeding molten metal into said axially disposed grooves from both ends of said grooves.

3. Apparatus for centrifugally casting metal comprising a rotatable mold having a hollow interior and a liner in engagement with the inner wall of said mold, said mold and liner having flutes or grooves formed in their contacting surfaces, the flutes or grooves being in 'alinement -to constitute matrices of bars of predetermined shape, means for actuating the mold to subject it to rotary movement, and means for feeding metal into the ends of the grooves while said mold is rotating.

4. Apparatus for centrifugally casting metal comprising a metal mold of substantially cylindrical form mounted for rotary movement, means for actuating said mold, said mold being of hollow construction and having matrices on the inner surface thereof extending to the ends of said mold, a liner disposed within said mold with its outer surface contacting the inner surface of the mold, said liner having matrices in cooperative alinement with the matrices of said mold, the matrices of the mold and liner cooperating to form castings of predetermined shape, and means for feeding molten metal into the ends of said matrices while the mold is subjected to rotation.

MAXWELL G. DUMAS.

Images