US2572037A - Method for pouring castings - Google Patents

Description

J. H. KEATING METHOD FOR POURING CASTINGS Oct. 23, 1951 Filed Feb. 18, 1948 3 Sheets-Sheet l INVENTOR. TOHN H KEAT/N6 BY flora nim M A 7'7'0/P/V5Y5 Oct. 23, 1951 J. H. KEATING 2,572,037

METHOD FOR POURING CASTINGS FiIed Feb. 18, 1948 3 Sheets-Sheet 2 INVENTOR. .7'0HN H- KEAT/NG A TTOPNEYS Oct. 23, 1951 J. H. KEATING memos FOR POURING CASTINGS' 3 Sheets-Sheet 3 Filed Feb. 18, 1948 INVENTOR. JOHN H- KEAT/NG Y r/Lmm Patented Oct. 23, 1951 UNITED STATES PATENT OFFICE 2,572,037 METHOD FOR POURING CASTINGS John H. Keating, Cleveland, Ohio, assignor to Monarch Aluminum Mfg. Company, Cleveland, Ohio, a corporation of Ohio Application February 18, 1948, Serial No. 9,156

2 Claims. (CL 22-209) This invention relates to the art of casting molten material and more particularly to a method by which the molten material may be poured into the mold at varying and predetermined rates dependent upon the conditions under which the casting is accomplished.

In filling a mold; particularly a permanent mold, it is essential that the material, generally metal, be poured more slowly at the beginning than at the end. Thisis necessary so that the material may flow freely and have access to all of the spaces in the mold and gate in which air pockets might otherwise be formed and also to insure that the proper casting temperatures are maintained within the mold cavity so the cast article is homogeneous in its physical composition and does not include entrapped air bubbles or blow holes.

The invention is particularly useful in permanent mold casting of aluminum articles and in the example shown in the drawings a cast aluminum lid for a pan is illustrated although it will be apparent that the invention is applicable to casting various other forms of aluminum objects in permanent molds and also is useful in casting other materials in other types of molds.

Heretofore, it has been customary for a skilled workman to determine by a cut and try method just what pouring speeds and changes in pouring speeds were essential for casting an object of given shape. Once this pouring cycle was ascertained that workman then continued to pour that particular shape because his skill was needed to maintain the pouring cycle he determined. A workman with the ability to ascertain such pouring cycles is more highly skilled than a workman whose task may consist only in pouring metal into a casting gate without regard for the rate at which the mold is filled. More efilcient production would be attained if the more skilled workman could be replaced by the less skilled workman once the necessary pouring rates of a given cycle are determined.

A general object of the present invention is to provide a method of casting by which the material is automatically poured into the mold at the different required rates of speed during the pouring cycle without regard for the skill of the workman involved. A further object of the invention is to provide a method by which a workman quickly fills a reservoir at the topo! a mold and through suitable orifices in the reservoir the material thereafter is fed at the desired rate into the mold cavity without further attention from that workman. Still another obiect is to provide a pouring reservoir for use at the top of the mold that comprises two or more compartments from each of which the molten material is fed through orifices of different size into the mold 5 cavity.

Other objects of the invention will become apparent from the following description and from the drawings in which a preferred embodiment is described and shown. The novel features of the invention are summarized in theclaims.

In the drawings: Y

Figure 1 is a front elevation of a two part mold and reservoir embodying the present invention. with the mold shown in the open position; Figure 2 is a section through Figure 1 as indicated by the lines 22 thereon but showing the mold closed; Figure 3 is a plan view of one form of pouring reservoir used with the present invention; Figure 4 is a section through Figure 3 as indicated by the lines 4-4 thereon; and, Figure 5 is a section through Figure 4 as indicated by the lines 55 thereon. The form of construction of mold and reservoir herein illustrated and described is for purposes of example only and the method and apparatus described represents only the claims.

The mechanism herein illustrated in front elevation in Figure 1 comprises a two part mold with one part secured to a frame and the other hinged to it on a vertical axis so it may be closed to form a mold cavity and opened to remove a casting. The hinged portion is in the form of a door ID provided with ears l2 that lie in vertical alignment with ears l3 on a stationary part l4 of the casting to form a hinge held by a pintle or pin 40 I5 about which the cover may be swung between the open and closed positions. At the side of the mold opposite the hinge is a lever ll pivotally supported .at l8 in a bracket 20 secured to the stationary frame of the mold indicated generally at 22. The lever carries a gear. tooth segment that engages a rack-toothed lock bar 24 slidable horizontally across a surface of the cover it to cam and lock the mold door in closed position.

I Accurate registration of the two parts of the mold 0 is attained by provision of the slightly inclined cam surface 21 (Figure 2) carried by the main frame of the mold and adapted to support and guide the cover 10 into position.

The main'mold portion and the door or cover portion It provided between them a mold cavity 3. G into which the molten casting material is poured. In the embodiment of the invention illustrated this cavity is in the form of a round and slightly convex aluminum. lid for a cooking utensil. Such a lid is only one of many objects that may be cast with the aid of the present invention which is primarily intended for use in making aluminum castings although it will be apparent that it may also be used where other materials are cast or molded.

The mold cavity C is bounded by a concave surface formed in a ring 30 positioned in a circular bore 32 of the cover l0, and is provided with an annular shoulder 33 that abuts a shoulder in the cover. A convex mold surface complementary to the concave surface is formed on a member 35 flanged at 31 to provide a shoulder that bears against the main fixed frame 22. The ring members 30 and 35 are secured to the cover 10 and frame 22 respectively. The frame 22 is supported on two cast triangular brackets 44 (Figure 2) by lugs 46 and 41 that are secured to the mold frame 22, and to the brackets by pins 48 and 45.

The mold cavity C is supplied with molten metal, in this case aluminum, through a gate 55 formed by recessing portions of the door l and' stationary part 22 as best shown in Figure 2. As a part of the gate there is provided a skeleton shaped series of passages formed partially in the front portion l0 and partially in the stationary part 22 as indicated generally at 60 in Figure l. The passages 60 include two opposite but otherwise similar circular passages 62 feeding through short passages 63 into inner circular passages 55 that in turn communicate directly with the circular mold cavity C. With this gate construction molten metal poured in at 55 fiows down through passages 62 and inwardly through passages 63 to the innermost passages 65 and from them into the mold cavity. By this form of gate the mold cavity is filled simultaneously from opposite sides through two long thin arcuate passages P resulting in a uniform supply of metal to the cavity with simultaneous removal of entrapped air providing a uniformly homogeneous and dense cast article.

It has been found that even with complicated gate structures such as just described for the casting of pan lids, or similarly complicated gates for other objects, many castings are defective. They are defective because the molten metal is supplied at incorrect rates of feed to the gate opening 55 so that neither the gate nor the mold fill properly and uniformly. Although theoretically it would be possible to construct an accurate feeding mechanism for pouring metal to such molds at controlled rates the fact that many different shaped objects are cast at a low unit cost makes it necessary for economical operation to provide some simpler and less expensive means of accomplishing the desired result, in the present case with the use of semi-skilled labor. As in dicated above it has been customary to employ a skilled workman who approximated the correct pouring rates and material fcr each form of casting and then proceeded manually to follow such pouring schedule as closely as he could in pouring all the castings of the run. The present invention enables a relatively unskilled workman to pour the castings of a run and frees the skilled workman to be available for other jobs that can carry a higher labor rate. Furthermore it decreases considerably the amount of time a workman needs to fill a particular mold and thus mak it ossible for a workman to fill a consider'ably larger number of molds during the day than heretofore has been possible.

When casting objects of the kind contemplated herein within the limits of accuracy required a reservoir as illustrated in Figures 3, 4 and 5 is provided to meter the molten material that travels through the passages 62 and 65 into the mold cavity. Generally speaking, it is necessary to begin to supply the metal to the cavity at a rather slow rate of speed which rate is continued for a short interval of time after which the main part of molten material is supplied at a much greater rate of speed until the mold cavity and most of the gate are completely filled. In casting other types and shapes of objects it is frequently necessary to employ different metering cycles and it will be understood that the invention is in no sense to be limited to the two compartment reservoir shown herein. A greater number of compartments than two may be employed although there will always be more than one, i. e., a simple funnel.

The reservoir illustrated in the drawings comprises a generally conical steel outer shell 10 that is divided into two portions by a central steel partition 12 such that one compartment 73 has a very much larger top area 14 than its companion compartment 15. The partition 72 does not entirely divide the two compartments but is slotted as indicated at 16 so that in effect the two compartments become one above the bottommostedge 18 of the slot. The molten metal is poured into the compartment 13 only, the large area of opening 14 making this easier and no metal enters the compartment 15 until the liquid level in compartment '13 has risen above the point 18. At the bottom of compartment '13 is an orifice discharging into the gate and a complementary orifice 82,- but of considerably greater area, is provided in the compartment 15. Theareas of these two orifices and the height of the slot in wall 12 are varied in each case properly to meter the amount of metal fed to the gate, the rate at which it is fed and the changes of rate during the pouring cycle. In some cases more than two compartments and orifices are provided better to control the pouring cycle.

With a reservoir of the particular dimensions and construction illustrated herein the followin pouring cycle takes place: As metal is first rapidly poured by a hand ladle into the compartment 13 it first passes out of the orifice80 into the gate opening 55. Since the metal is poured at a much faster rate than the orifice can accommodate it the liquid level rises until the point 18 is reached after which it overflows into the compartment 15 and thereafter also passes out through the orifice 82 into the gate opening 55 to supplement the metal passing through the orifice 80. This dual supply of metal to the mold then continues as the ladler pours the balance of the required volume of metal into the compartment 13 and until the liquid level drops below the level 18 and the compartment 15 by virtue of its enlarged orifice 82 and general volume becomes empty. From this time on to the end of the cycle metal passes only through the orifice Bil into the mold.

Thus a small amount of metal passes first through the orifice 80 at one rate after which a much larger quantity passes through both orifices 80 and 82 at an increased rate and finally a small quantity of metal passes only through the orifice 80 at the end of the pouring cycle.

The relative volumes of the two compartments l and 15 and the relative area of the orifices B0 and 82 are dependent upon the particular casting conditions required for a given mold cavity C and will be varied to meet different conditions. As stated above, under certain conditions more than two compartments may be required anda somewhat different gate construction than that described may be employed to produce the desired results. Accordingly it is not intended to limit the invention or the practice thereof to any particular reservoir construction except as a multi-compartmented reservoir with separate orifices in each and communication between the compartments permits proper metering of the molten material into the mold. The reservoir may be permanently secured to one or the other edges of the mold or it may be so constructed that it is merely set in place and easily removed entirely therefrom.

After the casting has solidified the lock bar 24 is withdrawn by the lever I1 and the cover I0 is swung around the pin l5 to open the mold and separate the convex and concave faces that form the mold cavity after which the casting is removed. Frequently the casting sticks to the convex face of the mold and to expedite its removal, fiuid, preferably compressed air, is admitted at an elevated pressure between the casting and the convex mold surface to spread out between the two and free the casting. This compressed air is admitted from a source 85 through a passage or opening 86 upon retraction of a plunger 81 connected to a piston mounted within an air cylinder and actuated in a known manner as disclosed in copending application Serial No. 681,302, now Patent 2,497,098, issued February 14, 1950 in the name of Gottlieb E. Schmid and assigned to my assignee. The passage 85 communicates with the center point of the mold cavity because this permits equal distribution of fluid pressure over the surfaces and also because any slight irregularity in the castingdue to deposit of material adjacent the opening is concealed when the knob is secured to the lid.

From the foregoing description it will be evident that I have provided an improved method and apparatus for simply and economically casting molten objects in such fashion that the molten material is supplied to the mold at varying ra es in accordance with the requirements of the casting cycle. The invention is simple-to make and use and produces results that are far superior to those heretofore obtained by ladling in the customary fashion and'at the same time is sufilciently inexpensive to be adapted to the casting of objects in either small lots or under conditions where a low unit price is essential.

I claim:

1. The method of introducing molten metal into a mold having a gate having a pouring opening adapted to receive molten metal and providing a passage leading to the mold cavity, comprising the steps of disposing a pcuring box over said opening, said pouring box having a plurality of orifices adapted to discharge into said opening, filling said pouring box with molten metal, discharging molten metal through one of said orifices while said pouring box is being filled and until the metal reaches a predetermined level in said pouring box, thereafter discharging molten metal through a plurality of orifices until said pouring box is filled, and continuing to discharge molten metal through a plurality of orifices until said pouring box is substantially empty. s

2. The method of introducing molten metal into a mold having a gate having a pouring opening adapted to receive molten metal and providing a passage leading to the mold cavity, comprising the steps of disposing a pouring box over said opening, said pouring box having at least two compartments separated by .an upwardly extending partition within the box, said partition providing an overflow passage between said compartments, each compartment having an orifice adapted to discharge into said opening, filling one compartment of said box with molten metal and discharging molten metal through the orifice thereof while said compartment is being filled, continuing to pour molten metal into said one compartment at a greater rate than the discharge therefrom through said orifice and overflowing molten metal into the other compartment of said box and discharging molten metal from the orifice of said other compartment, continuing to pour molten metal into said first compartment until the volume of metal required by themold has been poured and continuing to discharge molten metal through said orifices until said compartments are respectively emptied.

JOHN H. KEATING.-

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

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