US2731688A

US2731688A - Shrinkage control device for cast metal

Info

Publication number: US2731688A
Authority: US
Publication date: 1956-01-24
Anticipated expiration: 1973-01-24

Description

Jan. 24, 1956 w. L. JENKINS ETAL 3,731,688

SHRINKAGE CONTROL DEVICE FOR CAST METAL Filed Nov. 21, 1952 2 Sheets-Sheet 1 FIG. 3

INVENTORS WENDELL L.JENKINS a BY WALTjR J. B NETT i 1- r M ATTORNEYS Jan. 24, 1956 w. l... JENKINS EI'AL 2,731,638

SHRINKAGE CONTROL DEVICE FOR CAST METAL Filed Nov. 21, 1952 2 Sheets-Sheet 2 INVENTORS WENDELLLJENKINS & WALTER J. BENNETT ATTORNEYS SIHHNKAGE CGNTRGL DEVICE FUR CAST METAL Wendell L. .lenlrins and Walter 5. Bennett, Canton, Ohio, assignors to The Qanton (Zhaplet & Manufacturing Company, Stanton, @hio, a corporation of (this Application November 21, 1952, Serial No. 321,806 9 Claims. (Ql. 22-174) The invention relates generally to casting molten metal in sand molds and more particularly to a novel device for controlling the rate of cooling and shrinkage throughout those portions of a casting having substantial mass.

When molten metal is poured into the mold cavity, the central part of a boss or mass of metal stays molten while the outer periphery solidifies. As the molten metal within the outer shell cools, it solidifies from the shell inwardly, tending to cause shrinkage away from the center of the casting. 'lhis results in severe tensional strains tending to cause cracks or other porous defects in the finished casting, because by the time the metal at the center reaches solidification temperature there is insuflicient metal to fill the space defined by the already solidified outer shell, and cracks and voids are inevitably formed.

Attempts have been made to overcome these defects by utilizing a relatively large pouring sprue or riser which acts as a reservoir of molten metal to continue to feed molten metal into the center of the casting as it shrinks due to inwardly progressive solidification. Such risers have been unsatisfactory for a number of reasons, including the fact that the riser must always be so large in order to function effectively that a substantial excess of molten metal is required, and consequent additional time, labor and expense is involved.

Other attempts to overcome these defects have included the provision of so-called internal chills in the form of nails or masses of metal which are positioned to project into the mold cavity before the molten metal is poured so as to become fused or melted into the casting. These chills have had a number of disadvantages. If they have sufficient mass to produce effective chilling, they are apt not to be completely fused, particularly when the molten metal is poured near the end of a heat and hence has become somewhat cooled. Accordingly the bond between the chill and the casting may be poor, and in the case of pressure castings leaks may develop.

If a casting having improperly fused chills is later drilled, the drill may be thrown out of alignment by striking an angular or rounded surface of the unfused chill, or the drill may drive the chill completely out of the casting. Probably, the most serious objection to the use of internal chills is that they are very apt to entrap small bubbles of gas or steam, resulting in porous defects in the casting.

The principal object of the present invention is to provide a novel device which effectively controls the shrinkage in castings in such a way as to eliminate defects therein.

Another object is to accomplish the foregoing purpose while overcoming the disadvantages of prior devices as above set forth.

Finally, it is an object of the present invention to pro vide a novel device which accomplishes the foregoing purposes, and yet is economical to construct, easy to use, and completely effective in its operation.

We have discovered that the foregoing objects can be accomplished and the disadvantages of prior devices over- Z,73l,8 Patented Jan. 24, 1956 come, by the provision of an insert of novel design and construction adapted for positioning in a mold cavity where a substantial mass is to be formed, the insert having maximum surface area with small mass to control shrinkage, and having such configuration as to effectively avoid any entrapment of gases and to become completely fused into the casting.

The construction and operation of preferred embodiments of the novel device comprising the present invention are shown by way of example in the accompanying drawings and described in-detail in the specification hereof. It is to be understood that various changes and modifications can be made within the scope of the invention as defined in the appended claims.

Referring to the drawings:

Fig. l is a front elevation of the novel device;

Fig. 2 is an end elevation thereof;

Fig. 3 is a side elevation thereof;

Pig. 4 is a perspective view of a modified form of the invention;

lg. 5 is a fragmentary cross sectional view representing a mold cavity, showing one of the novel devices positioned therein in end elevation;

Fig. 6 is a similar view showing a side view of two of the devices positioned in a mold cavity; and

Fig. 7 is a similar view showing a side view of one of the modified devices of Fig. 4 positioned in a mold cavity.

Similar numerals refer to similar parts throughout the drawings.

The embodiment of the novel shrinkage control element shown in Figs. 1, 2, 3, 5 and 6 has a channel-shaped or trough-shaped body It) with an anchoring prong ll projecting longitudinally from one end. Viewed in cross section, the channel it) preferably has its legs 12 slightly inclined or divergent, as shown in Fig. 2, and connected by an arcuate portion 13:. The end surfaces of the channel 10 are inclined toward each other in directions from the base of the channel outwardly, as clearly shown at 14 and 15.

The anchoring prong 11 is tapered from the channel body It? to the outer end of the prong, so as to form sub stantially a point at its outer end for easy insertion into the sand of a mold. The prong is preferably 2. continu tion of the base of the channel, and the channel and prong may be formed from a single flat piece of metal. Preferably, the metal is of the same or similar metal as the casting in which it is to be inserted.

The form of the device shown in Fig. 4 has a channel body 10a which has legs 12a and is substantially identical to the channel ltl, but has a prong ila extending from each end. The prongs are bent angularly to form substantially right angles with the base of the channel 16a, although these angles may be varied somewhat as de sired. Otherwise the prongs Ila have the tapered shape as the prong 11.

While we have shown the channel body in both forms of the invention to be straight or linear, it is understood that within the scope of the invention it may be varied to a curved or angular shape. Also, the exact cross sectional shape may be modified, as long as the purposes of the invention are attained.

As indicated in Figs. 5, 6 and 7, the novel device may be positioned in various ways in mold cavities where a mass of molten metal is to be cast or solidified. Also, it is to be noted that the elements ltd may be made in a range sizes to suit difierent requirements. In Fig. 5, the element 10 is positioned vertically in the mold cavity C under the riser opening 16, anchoring prong 11 being inserted in the drag section 17 of the mold with the channel body extending upwardly into the cope section lb.

In Fig. 6 two of the novel elements are positioned horizontally in substantial alignment in the mold cavity C,

the prongs 11 being, inserted into opposite ends of the drag section of the mold. In Fig. 7 the two prong element 10a is positioned horizontally in the mold cavity C by inserting the' prongs 11a in the drag section of: the

mold cavity. While .the position of'the elements 1 i"- Ida in the mold cavity mayibe' varied to suit different conditions, the channel body. is always positioned open side up when the element is horizontal or inclined from the vertical. This is essential in order that no gas or steam bubbles become trapped by the channel during the casting operation. For the same reasons, the diverging sides 12 with their upper edges at right angles thereto, and the arcuate base connectingthe sides, insures that there are no horizontal surfaces above or below which gas bubbles will lodge. Similarly, the inclined endsl-and 15 permit the easy escape'of gaseswhen the element is in upright or substantially upright position, as shown in Fig. 5.

In the operation of the novel shrinkage control device, the elements or 10a are quickly and easily positioned in the mold cavity atplaces where substantial masses of molten metal are to be introduced and solidified, merely by inserting the tapered prongs into the sand of the mold. An important requirement is to position the elements open side up at all times.

When the molten metal is introduced into the mold cavity through the opening 16; as soon as the molten metal envelopes the shrinkage control element 10, it contacts the relatively large area of surface presented by the inner and outer surfaces ofthe channel and the element has a cooling and solidifying efiect upon the molten mass in that vicinity. This has the effectof making the rate of cooling throughout the mass more uniform.

At the same time, the relatively small mass of the trough shaped element it causes it to start immediately to melt and fuse with the molten metal, so that it is entirely fused and an integral part of the casting when solidification is complete. Thus, because of the large area of element 19, it has a substantial chilling effect to control shrinkage, and because of the small mass it becomes fused with the casting quickly even though the pouring temperature of the heat may have dropped.

Furthermore, all during the pouring and solidifying of the molten metal, the gas and steam rises easily along the inclined and curved surfaces of the element and no pockets or bubbles are formed. On the contrary, the inclined surfaces serve to aid or induce the gas to escape upwardly to the top of the casting.

Applicants have provided a novel device which is inexpensive to make and easy to" use, and which controls the shrinkage in castings to eliminate defects whileovercoming the disadvantages of prior devices.

What is claimed is:

1. An element for controlling the shrinkage of molten metal as it is cast in a mold cavity, comprising a channelshaped body having a rounded base with divergent legs, the end surfaces of said body being inclined toward each other in direction outwardly from the base, anda prong extending from one end of the base.

2. An element for controlling the shrinkage of molten metal as it is cast in a mold cavity, comprising a channelshaped body having a rounded base with divergent legs, the end surfaces of said body being inclined toward each other in directions outwardly from the base, and a prong 4 extending from one end of the base, and said body and prong being integral.

3. An element for controlling the shrinkage of molten metal as it is cast in a mold cavity, comprising a troughshaped body having a transversely curved base, the end surfaces of the body being inclined toward each other in directions away from the base, and a prong extending from one end of the base;

4. An element for controlling the shrinkage of molten metal as it is-cast in a mold cavity, comprising a troughshaped body having a transversely curved base, the end surfaces of the body being inclined toward each other in directions away from the base, and a prong extending longitudinally from one end of the base.

5. An element for controlling the shrinkage of molten metal as it is cast in a mold cavity, comprising a troughshaped body having a transversely curved base, the end surfaces of the body being inclined toward each other in directions away from the base, and a prong extending angularly from each end of the base.

6. In combination with a sand mold having a cavity and a pouring opening communicating with the upper end of said cavity, an element for controlling the shrinkage of molten metal in said cavity, said element having a trough-shaped body with legs extending from a curved base, the end surfaces of the body being inclined toward each other in directions away from the base, and a prong extending from the base into the mold and supporting said body in the mold cavity in a position with its trough upwardly open.

7. In combination with a sand mold having a cavity and a pouring opening communicating with the upper end of said cavity, an element for controlling the shrinkage of molten metal in said cavity, said element having a channel-shaped body, said body comprising a transversely rounded base with divergent legs, the end surfaces of said body being inclined toward each other as they extend away from the base, and a prong extending from the base into the mold and supporting said element with its body projecting into the central area of the mold cavity with the channel in upwardly open position.

8. An element for controlling the shrinkage of molten metal as it is cast in a mold cavity, comprising an elongated troughshaped body having inclined sides and inclined ends, and a prong extending from one end of said body.

9. An element for controlling the shrinkage of molten metal as it is cast in a mold cavity, comprising a troughshaped body having a transversely curved base, the end surfaces of the body being inclined away from the base, and a prong extending from one end of the base.

References Cited in the file of this patent UNITED STATES PATENTS 1,618,016 Leek Feb. 15, 1927 1,862,908 Richardson June 14, 1932 2,084,794 Dockray et a1. June 22, 1937 2,170,103 Westover Aug. 22, 1939 OTHER REFERENCES The Foundry, March 1945, page 166.

Claims

1. AN ELEMENT FOR CONTROLLING THE SHRINKAGE OF MOLTEN METAL AS IT IS CAST IN A MOLD CAVITY, COMPRISING A CHANNELSHAPED BODY HAVING A ROUNDED BASE WITH DIVERGENT LEGS, THE END SURFACES OF SAID BODY BEING INCLINED TOWARD EACH OTHER IN DIRECTION OUTWARDLY FROM THE BASE, AND A PRONG EXTENDING FROM ONE END OF THE BASE.