US2502767A - Apparatus for molding castings having deep fins - Google Patents

Description

Aprifi 4, 1950 w. M. VENNER ETAL APPARATUS FOR MOLDING CASTINGS HAVING DEEP FINS 2 Sheets-Sheet 1 Filed Jan. 11, 1944 wmsav ca w k g 53 INVENTORS, WILL/AM M VENNER AND Pmcy L.BOW$ER,JR.

d'SM ATTORNEYS FIGZQ.

April 1950 w. M. VENNER ETAL 2,502,767

APPARATUS FOR MOLDING CASTINGS HAVING DEEP FINS Filed Jan. 11, 1944 2 Sheets-Sheet 2 3 FIG,3

ii? A l Q 7% \Q v INVENTORS,

WILLIAM M. VENNER AND Pmcv 1.. Ban 55R, JR.

By W Arron/vans Patented Apr. 4, 1950 APPARATUS FOR MOLDING CASTINGS HAVING DEEP FIN S William M. Venner, Clayton, and Percy L. Bowser,

Jr., University City, Mo., assignors to The Sterling Corporation, St. Louis, Mo., a corporation of Delaware Application January 11, 1944, Serial No. 517,766

3 Claims.

This invention pertains to an apparatus for casting metal, particularly for making castings having thin fins, such as cooling fins for internal combustion engines and the like. The invention is described in this specification as applied to the casting of a so-called cylinder muff used in connection with internal combustion engines, although the invention may be appiled to other castings having fins.

In casting metal into a form of a thin plate or fin, difficulty is often encountered in causing the metal to flow into the remote portions of the fin molding cavity as the metal tends to cool and set before reaching the farthest portions of a narrow deep cavity. As a consequence, such castings are often defective in having one or several fins incomplete.

One of the objects of this invention, therefore, is to provide an apparatus for casting shapes having such fins which will insure that the metal flows to the remote portions of the molding cavities so as to form complete castings.

Another difficulty in molding this type of casting is that of forming the mold cavity accurately to the desired shape. In many cases closely spaced fins are required which are of considerable depth and therefore require a deep narrow molding cavity. Such cavities are difficult to form by the ordinary means.

Another object of this invention, therefore, is to provide a novel form of mold so designed as to render the accurate formation of the fin molding cavities easy to be carried out with ordinary tools.

Another object is to provide such a mold by which the metal may be poured by gravity in a simple manner as by the use of an ordinary ladle.

Another object is to provide such a mold constructed in sections Which may be assembled to form a complete mold during the casting operation and which may be separated in a simple manner to free the casting for removal from the mold.

Another object is to provide an apparatus for casting a. muff, provided with spaced radially projecting fins of an aluminum alloy.

Further objects will appear from the-following description taken in connection with the accompanying drawings in which Figure 1 is a front elevation of a mold embodying this invention and for performing the method,

Figure 2 is a section on line 2--2 of Figure 1,

Figure 2a is an enlarged detail of one of the plates forming the center portion of the mold shown in Figure 2,

Fig. 2b is an enlarged detail of plates forming the upper portion of the mold shown in Fig. 2,

Fig. 2c is an enlarged detail of plates forming the lower portion of the mold shown in Fig. 2,

Figure 3 is a central section showing a casting of a so-called cylinder muff which may be cast by means of the mold shown in Figure 2,

Figure 4 is a View in elevation of a complete molding apparatus adapted for carrying out the method of this invention,

Figure 5 is a right hand side view of Figure 4.

Generally stated, and in accordance with an illustrative embodiment of this invention, a mold, having spaced cavities radiating from a central opening, is rotated about the axis of the cavities, and the molten metal is introduced into the cavities through the opening during such rotationso as to cause the metal to be projected by centrifugal force into .the cavities; this is continued until the cavities overflow to connect them in order to form the body of the muff. The rotational speed increases with the radial depth of the cavities. The draft of the cavities at the axial center of the mold increases from this center to the ends thereof. The mold is of sectional form so as to permit separations of the sections in order to free the casting. Means is provdied for separating the mold sections and this means is preferably such as to cooperate with successive sections.

Referring to the drawing and more particularly to Figures 1 and 2, the mold selected for illustration as embodying this invention is made up mainly of a series of. flat plates l arranged in stacked relation, as indicated in Figure 2, and secured together in that relation by any suitable means, such as cap screws 2.

It will be noted that the casting shown in Figure 3 comprises a main cylindrical body 3 surrounded by closely spaced ring shaped fins 4. These fins are arranged substantially in planes perpendicular to the axis of the cylinder 3. They are relatively thin in their axial dimensions and relatively deep in a radial direction.

In order to form the mold cavity in which one of these fins 4 may be cast, the plates I are formedeach with an inner opening of a diameter equal to that of the outside diameter of the cylindrical body 3, or, in other words, equal to the inside diameter of the spaces between the fins 4. Each plate I is substantially fiat so as to have two planar faces 5 and 6. Cut into one or both of the faces 5 and 6 is a hollowed form indicated at I having the shape of half of one of the fins 4. The other face 6 may also be formed with a similar hollowed portion 8. These hollows or depressions may be of circular form when viewed as looking at one of the faces or 5. Such a cavity or depression may be formed easily by turning in a lathe or similar machines. The inner walls of the cavities 1 and 8 turn to ward each other so as to meet at the point 9, providing a circular inner edge forming the inside diameter mentioned above which forms the bottom of the space or groove between two of the fins 4. If new two plates such as shown in Fig. 2a are assembled face to face, the half cavity of one may be made to match the half cavity 7 of the other, thereby combining to form a complete fin molding cavity. Any number of such plates I may be assembled together, as shown in Fig. 2, in stacked relation and may thus be built up to form a complete mold having a plurality of closely spaced fin molding cavities.

In accordance with this invention, the complete mold, shown in Fig. 2, is divided into secat !2 and I3 may be thicker than the plates I so as to form a support therefor, and may be provided each with only one cavity 7 or 8 arranged on the inside face thereof to cooperate with the corresponding half cavity on the adjacent plate I, so as to form the end fin of the casting shown in Fig. 3. These end plates I2 and I3 are, Of course, similarly divided into sectors. Accordingly, each assembly of plates provides a mold section in sector form adapted for assembly with the other sections as shown in full lines in Fig. 1, so as to form the complete mold.

In order to insure proper registry of the various sectors with each other two of the sections are provided with ears l4 secured to the mold sections by screws l5 or other suitable means. As will be seen from Fig. 1, the ears M are secured only to the right and left sectors. However, they are mounted upon angular faces I5 of those sectors corresponding to similar angular faces on the upper and lower sectors. The arrangement is such that when the four sectors are assembled, as shown in Fig. 1. the ears M will engage the upper and lower sectors to force them into proper alignment and retain them in such alignment. In order to make the assembly secure, any suitable locking means, such as bolts I! may be provided to engage the ears H. to lock the sectors in assembled relation during the molding operation.

In order to mount the mold for use, an apparatus, such as shown in Figs. 4 and 5, may be provided. This comprises a suitable table or support l8 and upon which may be mounted a bracket l 9 carrying suitable journals for a rotatable spindle 2 I. Mounted on the spindle 2| is a face plate 22 which may be provided with radial T-slots 23. Each of the sectors of the mold ma then be provided with slide members 24, also T-shaped to slide in the slots 23. Thus, said slots provide ways upon which the mold sectors may be moved for separating and reassembling the same.

The mold may thus be mounted upon the face plate 22, as shown in Figs. 4 and 5. With the several sectors assembled together and locked in place by means of the devices H, the spindle 2! may be rotated to rotate the mold. For this pur- These sectors may then be separated pose a motor 25 may be connected by a belt 26 to a suitable pulley 2'! on the spindle 2|.

The mold may thus be set into rotation on the spindle 2!. While the mold is in rotation, the casting metal may be poured thereinto through a central opening 28 provided in the end plate l2. The pouring may be carried out by gravity by means of a ladle 29 or other suitable means. As the mold is driven in rotation, the metal upon entering the mold will be thrown by centrifugal force to the outermost limits of the fin molding cavities. Thus a rapid movement of the metal to the outermost parts of the cavities is insured, so that those portions of the cavities will be completely filled before the metal has time to become chilled. The continued rotation of the mold during the pouring operations keeps the molten metal under centrifugal force tending to force it to the outermost parts of the mold. Accordingly, the effect of pressure casting is obtained by maintaining a metal under the pressure induced by centrifugal force in this manner. The pouring may be continued until the mold is filled to a given level measured radially. This level may be at any desired point according to the thickness of the body 3 which is desired. Usually, of course, a little additional metal is poured into the casting so as to provide for machining the bore of the cylindrical body 3.

When the metal has been poured into the mold to the desired depth, the rotation of the spindle 2| may be stopped. For this purpose a brake band 30 engaging a pulley 3| on the spindle 2! may be manipulated to bring the mold to rest in a short time. It will be understood, of course, that sufficient time is allowed for the casting metal to set or solidify before the rotation of the mold is stopped. When the mold has been stopped, the locking device I! may be released and the various mold sectors separated from the casting. For this purpose it may be convenient to provide a pneumatic or hydraulic cylinder 32, provided with suitable attaching link 33, adapted to engage ears 34, one of which is provided on each mold sector. The link and the ears may be perforated to receive a connecting pin 36. A pin 3'! on a bracket 38 may also engage sockets 39 in the plate 32 to position the same. The cylinder 32 may be operated by any suitable control means, such as a valve 35, so as to draw the mold sector away from the casting. The different sectors may thus be brought into alignment with the cylinder 32 in any desired sequence and the cylinder operated to move the sector away from the casting. When the casting has thus been freed sufiiciently for removal, it may be taken out of the mold.

After each casting has been molded, the sectors may be reassembled and looked, as described above, and then set into rotation for molding a new casting.

It will be seen that this invention provides a method and means for making finned castings, such as the cylinder muff shown in Fig. 3 in a simple manner and one which will insure sound castings with complete fins. The pouring of the metal is done while the mold is in rotation and, as described above, a pressure casting effect is obtained by the operation of centrifugal force. The mounting of the mold is such that it may be easily and quickly freed from one casting and reassembled preparatory to molding a subsequent casting. Thus, a rapid operation may be obtained so as to promote a maximum production rate for making castings.

While the castings shown in Figure 3 are of a type of which many are in use on engine cylinders, the method and apparatus of this invention may be applied to mold many other types of finned castings. It will be noted that the radial depth of the half cavities 1 and 8 may be varied so as to vary the general contour of the complete casting. lhis is illustrated in Fig. 3 by the tapered general outline of the casting shown.

As these casting are often made of metal having a high rate of thermal expansion, such as aluminum or magnesium or their alloys, provision is made in the mold of Fig. 2 for the high rate of shrinkage of such metal upon cooling and solidifying. As indicated by the legends, ac-

companying Fig, 2, a certain number of the fin molding cavities in the middle of the mold, in this instance four are formed with draft in both directions. Accordingly, both the half cavities in each plate I of this middle portion are provided with draft On both sides. However, the outer portions of the mold including the cavities on each side of this-middle section are formed with draft on the inside, that is, toward the middle portion, but not on the outside. the draft increases progressively from the middle portion of the mold toward both ends, so that shrinkage toward the middle from both ends is provided for and the casting may be easily withdrawn from the mold.

In the rapid operation of the apparatus, as shown in Figures 4 and 5, the ears 14 play an important part in securing proper closure of the mold. It will be noted that when the two side sections in Fig. 1 are drawn together, so as to engage the locking devices H, the action of the ears 14 upon the inclined faces of the upper and lower sectors will tend to force them into proper position in which they will then be held by the locking devices ll. These locking devices may be quickly detachable as by slotting one or both lugs 40 as shown at 4|, Figure 5.

This invention is particularly applicable to the casting of aluminum and magnesium alloys. As an example, of an aluminum alloy containing, for instance, 6% copper, 6% silicon, 0.3% magnesium, 1% iron, and the balance aluminum, except impurities as are ordinarly encountered in ingots, the procedure is as follows: The molten metal at a temperature of about 1325 F. is introduced quickly into the mold while the latter is rotating at a speed which, for an outside diameter of the cavity of about 9 can be about 390 revolutions per minute, so that the product of the revolutions per minute and the diameter in inches is about I 3600. The mold is opened as soon as crystallization has been compensated for which will be about 2 minutes after pouring has been completed for the size mold noted above.

While the invention has been described as embodied in the particular apparatus shown in the drawings, it will be understood that various It will be noted, therefore, that changes in the details of construction and operation within the scope of the appended claims may be made without departing from the spirit of this invention, and that accordingly the invention is not limited to the specific details shown and described.

Having thus described the invention, What is claimed is:

1. A mold for molding castings having fins,

\ comprising, a series of fiat plates assembled in adjacent substantially parallel relation, the adjacent faces of said plates having half-cavities adapted in pairs to mold the fins, said plates being stacked to form closely spaced fin-molding cavities, and said cavities being formed with draft in opposite directions on opposite sides of an intermediate reference point to allow for shrinkage of the casting toward that point.

2. A mold for molding castings having fins, comprising, a series of flat plates assembled in adjacent substantially parallel relation, the adjacent faces of said plates having half-cavities adapted in pairs to mold the fins, said plates being stacked to form closely spaced fin-molding cavities, and said cavities being formed with varying draft increasing with their spacing from a fixed reference point to allow for shrinkage of the casting toward that point.

3. An apparatus for casting a muff provided with spaced radial fins, comprising, a permanent mold having spaced cavities radiating from a central opening adapted to receive the molten etal, the draft of the cavities increasing prog essively from the middle portion of the mold toward the ends thereof, and means for rotating said mold about the axis of the cavities.

WILLIAM M. VENNER. PERCY L. BOWSER, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,320,744 De Lauaud Nov. 4, 1919 1,425,927 Wolf Aug. 15, 1922 1,450,552 Jombard Apr. 3, 1923 1,517,57 9 Pashley Dec. 2, 1924 1,556,138 Wehr Oct. 6, 1925 1,691,464 Brown Nov. 13, 1928 1,769,456 Pickering July 1, 1930 1,978,765 Sargent et a1 Oct. 30, 1934 2,326,418 Van Amerongen et al Aug. 10, 1943 2,369,067 Mayer Feb. 6, 1945 2,391,523 Sorensen Dec. 25, 1945 FOREIGN PATENTS Number Country Date 531,107 Germany Aug. 5, 1931 681,401 Germany Sept. 21, 1939

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